На главную

 
Научные подразделения Центра
Научная библиотека
Научные советы
Издательская деятельность
Труды конференций
История ИК СО РАН
Версия для печати | Главная > Центр > Издательская деятельность > Annual Review > Краткое содержание номеров > Annual Review 2012

Abstracts

Страницы 1 - 3 из 3
Начало | Пред. | 1 | След. | Конец | По стр. 

Quantum-Chemical Investigations

MODELING OF THE MECHANISM OF ONE-ELECTRON TRANSFER FROM THE PERYLENE MOLECULE TO THE OXYGEN MOLECULE 3O2 IN THE HF MEDIUM

I.V. Kuz’min*, V.N. Solkan*, G.M. Zhidomirov, V.B. Kazanskii* (*Zelinsky Institute of Organic Chemistry, Moscow, Russia)

Kinet. Catal., 52(2) (2011) pp. 192-196.

The thermodynamic parameters of the formation of the perylene radical cation in anhydrous hydrogen fluoride containing dissolved dioxygen were calculated by the ab initio method MP2. The protonated product of HF autoprotolysis was modeled as the H(FH)3+ cluster. The 3O2 molecule was found to bind to the linear H(FH)3+ cluster via a hydrogen bond. As the charge and multiplicity of the system change upon the capture of an electron, the oxygen-hydrogen fluoride cluster complex undergoes rearrangement to yield the hydroperoxyl radical OOH incorporated in a cycle formed by HF molecules. The free energy of electron transfer from the perylene molecule to the 3O2 molecule in the HF medium is about -38 kcal/mol.

A QUANTUM-CHEMICAL MODEL OF THE INHIBITION MECHANISM

G.A. Yuldasheva*, G.M. Zhidomirov, A.I. Ilin*

(*Anti-Infective Drug Research Center, Almaty, Kazakhstan)

Nat. Sci., 3(7) (2011) pp. 573-579.

The interaction of molecular iodine with virus DNA nucleotide is studied by ab initio RHF/3-21G** method. Formation of the nucleoprotein complex of the HIV DNA, molecular iodine and the HIV-1 integrase co-factor is considered to cause the inhibition action of the integrase enzyme. Experimental data on the anti-HIV effect of the molecular iodine complex compounds and the results of calculations suggest that molecular iodine contained in iodine polymer complexes may be considered as a compound inhibiting the catalytic center of the integrase enzyme. Unlike the known integrase inhibitors, molecular iodine also changes the virus DNA structure and produces the N-I bond in the purine bases of adenosine and guanosine nucleotides.

OXIDE CLUSTERS AS SOURCE OF THE THIRD OXYGEN ATOM FOR THE FORMATION OF CARBONATES IN ALKALINE EARTH DEHYDRATED ZEOLITES

A.V. Larin*, A.A. Rybakov*, G.M. Zhidomirov, A. Mace**, A. Laaksonen**, D.P. Vercauteren***

(*Moscow Lomonosov State University, Moscow, Russia; **University of Stockholm, Stockholm, Sweden; ***University of Namur, Namur, Belgium)

J. Catal., 281(2) (2011) pp. 212-221.

It is shown that carbonates can be formed with almost no energetic barrier from CO2 and metal-oxide binuclear MOxM species (M = Mg, Ca, Sr, Ba, with X = 1–4, depending on the cation) in alkaline earth zeolites, mordenite (MOR) and phillipsite (PHI), on the basis of quantum mechanical density functional theory (DFT) calculations at both isolated cluster and 3D periodic levels. The participation of MOxM species (X = 1 and 3) explains the source of the third O atom in CO3 species in dehydrated zeolites, on the basis of a good agreement between the calculated and experimental positions of the asymmetric and symmetric CO3 vibration bands, of the ratio of their intensities, and of the weak dependence versus the cation and framework type. The reaction of formation of dimethylcarbonate from CaCO3Ca in the 8-membered (8R) ring of MOR and methanol has also been considered, suggesting the carbonate activity as the source of CO2 at elevated temperatures.

DFT INVESTIGATION OF CO OXIDATION OVER Mg EXCHANGED PERIODIC ZEOLITE MODELS

A.A. Rybakov*, A.V. Larin*, G.M. Zhidomirov, D.N. Trubnikov*, D.P. Vercauteren** (*Moscow Lomonosov State University, Moscow, Russia; **University of Namur, Namur, Belgium)

Comput. Theor. Chem., 964(1-3) (2011) pp. 108-115.

A new CO oxidation mechanism occurring at (MgO2Mg)2+ oxide clusters in different zeolites is modeled at both the periodic DFT (PDFT) level for Mg-phillipsite and with the cluster approach for zeolite Y and mordenite. Using PDFT, the authors obtained a value of reaction activation energy (15.3 kcal/mol) that is lower than the one obtained using the isolated cluster approach (35 kcal/mol).

The main reason of the lower barrier is the strong CO chemisorption, which was not obtained with the cluster approach. The lower oxidation activity of the Mg zeolite forms is due to the smaller number of active singlet MgOxMg species compared to those in the other alkaline earth zeolites.

Cu(II)-Alkyl CHLOROCOMPLEXES: STABLE COMPOUNDS OR TRANSIENTS? DFT PREDICTION OF THEIR STRUCTURE AND EPR PARAMETERS

E.N. Golubeva*, O.I. Gromov*, G.M. Zhidomirov(*Moscow Lomonosov State University, Moscow, Russia)

J. Phys. Chem. A, 115(28) (2011) pp. 8147-8154.

DFT calculations were used for studying the structure and reactivity of organocuprates(II) usually considered as intermediates with very weak Cu-C bond. It was found that calculated principal g-tensor values of model compounds RCu(II)Cl2- are similar to the experimentally found values for organocopper product of photolysis of quaternary ammonium tetrachlorocuprates. The calculations confirm that the most of organocuprates(II) could be stable at ambient conditions, and short lifetimes of organocuprates(II) in solutions or soft matrices are caused by their high reactivity in various bimolecular processes; the rate of those may be close to the rate of diffusion controlled reactions. The charges, spin densities, and d-orbital populations of the Cu atom in them are typical for bivalent copper complexes. Natural bond orbital analysis of organochlorocuprates(II) confirms the formation of polar σ-bond between copper and carbon atoms.

ROLE OF THE SURFACE HYDROXYL GROUPS OF MODIFIED TITANIUM OXIDE IN CATALYTIC ETHYLENE OXIDE HYDRATION

D.E. Zavelev*, M.V. Tsodikov*,cvG.M. Zhidomirov, R.A. Kozlovskii* (*Topchiev Institute of Petrochemical Synthesis, Moscow, Russia)

Kinet. Catal., 52(5) (2011) pp. 659-671.

A quantum-chemical study of the mechanism of ethylene oxide hydration on titanium oxide (anatase) modified with phosphorus additives was performed. It was demonstrated that the hydroxyl groups of the anatase surface are of importance for the activation interaction of ethylene oxide with the catalyst surface. The activation of the ethylene oxide molecule and proton transfer occurs with the participation of these hydroxyl groups. It was found that the modification of the titanium oxide surface with phosphorus additives plays a crucial role in proton transfer.

EFFECT OF LATTICE STRAIN ON HYDROGEN DIFFUSION IN Pd: A DENSITY FUNCTIONAL THEORY STUDY

H. Gronbeck*, V.P. Zhdanov (*Chalmers University of Technology, Göteborg, Sweden)

Phys. Rev. B: Condens. Matter, 84(5) (2011) 052301 (4 pp.)

The density functional theory (DFT) is used to study the effect of lattice strain on hydrogen diffusion in Pd. The activation energy for this process is found to increase dramatically with increasing compressive lattice strain. In particular, the activation energy is close to double for an isotropic compression of 5% both in the alpha and beta phases. For tensile strain, the activation energy is instead decreased. This finding has important consequences for the interpretation of various kinetic processes occurring with participation of hydrogen and other interstitial atoms in macroscopic solid samples and nanoparticles.

DFT STUDIES OF PALLADIUM MODEL CATALYSTS: STRUCTURE AND SIZE EFFECTS

I.V. Yudanov, A. Genest*, N. Rösch* (*Technische Universität München, Garching, Germany)

J. Clust. Sci., 22(3) (2011) pp. 433-448.

An important task for theory is the multi-scale modeling of catalytic properties of nanocrystallites with sizes ranging from clusters of few metal atoms to particles consisting of 103–104 atoms. To explore catalytic properties of nanosized metal catalysts, the authors developed an approach based on three-dimensional symmetric model clusters of 1–2 nm (~100 metal atoms) with fcc structure, terminated by low-index surfaces. With this modeling technique one is able to describe at an accurate DFT level various catalytic and adsorption properties of metal nanoparticles in quantitative agreement with experimental studies of model catalysts deposited on thin oxide films. Metal nanocrystallites exhibit properties that can significantly vary with their size and shape.

MOLECULAR MECHANISM OF THE FORMIC ACID DECOMPOSITION ON V2O5/TiO2

CATALYSTS: A PERIODIC DFT ANALYSIS

V.I. Avdeev, V.N. Parmon

J. Phys. Chem. C, 115(44) (2011) pp. 21755-21762.

Molecular and dissociative forms of formic acid adsorption on the V2O5/TiO2 model surface, possible intermediates, and transition states along of the dehydrogenation (HCOOH → CO2 + H2) and dehydration (HCOOH → CO + H2O) pathways have been studied by the periodic density functional theory. The CI-NEB analysis of the reaction pathways showed that two types of molecular adsorbed HCOOH species initiate two completely different reaction channels. The first more stable adsorbed form is transformed into the surface formates, which decompose according to the “formate mechanism” to yield products of dehydrogenation, whereas the second weakly adsorbed molecular form decomposes, releasing CO and forming surface hydroxyls. Recombination of two surface hydroxyl groups V–OH to form adsorbed H2O, followed by water desorption, completes the catalytic dehydration cycle without participation of the formate species. Comparison of the reaction pathways demonstrates that both dehydrogenation and dehydration of formic acid may occur over VOx/TiO2 model catalysts with the preferable dehydration pathway.

ADSORPTION ENERGY OF THE As ATOM ON THE Pd(111) SURFACE ACCORDING TO THE DENSITY FUNCTIONAL THEORY DATA

S.E. Malykhin, M.Yu. Burylin*, S.Yu. Burylin*, I.L. Zilberberg (*Kuban State University, Krasnodar, Russia)

J. Struct. Chem., 52(6) (2011) pp. 1098-1101.

Density functional theory in the plane wave basis set is used to study As adsorption on the Pd(111) surface in order to determine the action of a palladium chemical modifier used in electrothermal atomic absorption spectrometry (ETAAS). The calculated heat of desorption of the arsenic atom is 435 kJ/mole, which corresponds to the activation energy of arsenic atomization of 439 kJ/mole (in the range of high temperatures T > 1828 K), obtained by ETAAS. Based on the calculated data, the action of the palladium modifier for the determination of As is assumed to be controlled by the process of chemisorption.

AN ab initio STUDY OF ELECTROCHEMICAL vs. ELECTROMECHANICAL PROPERTIES: THE CASE OF CO ADSORBED ON A Pt(111) SURFACE

M.I. Mamatkulov, J.-S. Filhol* (*Université Montpellier, Montpellier Cedex, France )

Phys. Chem. Chem. Phys., 13(17) (2011) pp. 7675-7684.

The authors have studied electrochemical vibrational and energy properties of CO/Pt(111) in the framework of periodic density functional theory (DFT) calculations. The authors have used a modified version of the previously developed Filhol-Neurock method to correct the unphysical contributions arising from homogeneous background countercharge in the case of thick metallic slabs. The stability of different CO adsorption sites on Pt(111) (Top, Bridge, Hcp, Fcc) has been studied at constant electric field. The energies are dominated by the surface dipole interaction with the external electric field: a strong positive electric field favors the surfaces with the lower dipole moment (that correspond to the ones with the lower coordination). The Stark tuning slope of the CO stretching frequency for a Top site was calculated for different surface coverages in very good agreement with both experimental and other theoretical results. Finally, an analysis of the origin of Stark shifts showing that the total Stark effect can be split into two competing components have been performed. The first one corresponds to the direct effect of charging on the C-O chemical bond: it is referred as an electrochemical effect. The second is the consequence of the surface dipole interaction with the applied electric field that modifies the C-O distance, inducing a change of the C-O force constant because of C-O bond anharmonicity: it is referred as the electromechanical effect. In the CO/Pt(111) case, the dominant contribution is electromechanical. The electrochemical contribution is very small because the electronic system involved in the surface charging is mostly non-bonding as analyzed by looking at the surface Fukui function.

Monte-Carlo Simulations to Study Physicochemical Processes

ARE THE COMPLEX DISTRIBUTED GENETIC NETWORKS INHERENTLY OSCILLATORY AND CHAOTIC?

V.P. Zhdanov

JETP Lett., 93(1) (2011) pp. 41-45.

Complex mRNA-protein networks with distributed regulation of gene transcription are often mimicked by random Boolean networks. According to this mapping, the gene-expression kinetics are expected to depend strongly on the network connectivity, m. Specifically, the kinetics are predicted to be oscillatory or chaotic for m > 2. The authors analyze this problem in more detail by using an accurate model explicitly describing the mRNA-protein interplay with randomly organized transcriptional regulation. Contrary to the expectations, mean-field calculations and Monte Carlo simulations performed for m = 1, 2 and 4 show that oscillations and chaos are lacking irrespective of m.

KINETIC MODELS OF GENE EXPRESSION INCLUDING NON-CODING RNAs

V.P. Zhdanov

Phys. Rep.-Rev. Sec. Phys. Lett., 500(1) (2011) pp. 1-42.

n cells, genes are transcribed into mRNAs, and the latter are translated into proteins. Due to the feedbacks between these processes, the kinetics of gene expression may be complex even in the simplest genetic networks. The corresponding models have already been reviewed in the literature. A new avenue in this field is related to the recognition that the conventional scenario of gene expression is fully applicable only to prokaryotes whose genomes consist of tightly packed protein-coding sequences. In eukaryotic cells, in contrast, such sequences are relatively rare, and the rest of the genome includes numerous transcript units representing non-coding RNAs (ncRNAs). During the past decade, it has become clear that such RNAs play a crucial role in gene expression and accordingly influence a multitude of cellular processes both in the normal state and during diseases. The numerous biological functions of ncRNAs are based primarily on their abilities to silence genes via pairing with a target mRNA and subsequently preventing its translation or facilitating degradation of the mRNA-ncRNA complex. Many other abilities of ncRNAs have been discovered as well. The review is focused on the available kinetic models describing the mRNA, ncRNA and protein interplay. In particular, the authors systematically present the simplest models without kinetic feedbacks, models containing feedbacks and predicting bistability and oscillations in simple genetic networks, and models describing the effect of ncRNAs on complex genetic networks. Mathematically, the presentation is based primarily on temporal mean-field kinetic equations. The stochastic and spatio-temporal effects are also briefly discussed.

PERIODIC PERTURBATION OF THE BISTABLE KINETICS OF GENE EXPRESSION

V.P. Zhdanov

Physica A, 390(1) (2011) pp. 57-64.

Kinetics of gene expression may be bistable or oscillatory due to the feedbacks between the RNA and protein synthesis. In complex genetic networks, kinetic oscillations may influence bistability. Following this line, the authors have performed a mean-field analysis and Monte Carlo simulations of periodic perturbation of the bistable kinetics of expression of two genes with mutual suppression of the mRNA production due to negative regulation of the gene transcription by protein. The perturbation is realized via modulation of the rate of the mRNA formation. In the mean-field kinetics, the mRNA and protein concentrations repeat themselves during each period. In the stochastic kinetics, this is also the case, provided that the modulation amplitude is small. If the modulation is appreciable, the latter kinetics exhibit new features. Specifically, the model predicts stochastic intermittence of the states of the genes. If the modulation amplitude is close to maximum, the change of the gene states during subsequent perturbation periods occurs fully at random. Taking into account that the model the authors use is generic, the results obtained are expected to be of interest far beyond the biophysics and biochemistry of gene expression.

GROWTH AND GLOBAL GENE EXPRESSION OF EUCARYOTIC CELLS

V.P. Zhdanov

Biophys. Rev. Lett., 6(1-2) (2011) pp. 1-12.

The authors present a kinetic model describing the growth of eukaryotic cells or, more specifically, the dependence of the cell volume on time in terms of the global interplay of the mRNA and protein synthesis and degradation and lipid synthesis. Addressing two long-standing questions in this interdisciplinary field, the authors explain why the average protein concentration in growing cells is nearly constant and the growth can accurately be fitted by using a bilinear or exponential function.

NON-CODING RNAs AND COMPLEX DISTRIBUTED GENETIC NETWORKS

V.P. Zhdanov

Central Eur. J. Phys., 9(4) (2011) pp. 909-918.

In eukaryotic cells, the mRNA-protein interplay can be dramatically influenced by non-coding RNAs (ncRNAs). Although this new paradigm is now widely accepted, an understanding of the effect of ncRNAs on complex genetic networks is lacking. To clarify what may happen in this case, a mean-field kinetic model was proposed describing the influence of ncRNA on a complex genetic network with a distributed architecture including mutual protein-mediated regulation of many genes transcribed into mRNAs. ncRNA is considered to associate with mRNAs and inhibit their translation and/or facilitate degradation. Results are indicative of the richness of the kinetics under consideration. The main complex features are found to be bistability and oscillations. One could expect to find kinetic chaos as well. The latter feature has however not been observed in calculations. In addition, the authors illustrate the difference in the regulation of distributed networks by mRNA and ncRNA.

KINETIC MODELS OF THE INTERFERENCE OF GENE TRANSCRIPTION TO ncRNA AND mRNA

V.P. Zhdanov

Chaos, 21(2) (2011) 023135 (7 pp.).

The experiments indicate that the transcription of genes into ncRNA can positively or negatively interfere with transcription into mRNA. Two kinetic models are proposed describing this effect. The first model is focused on the ncRNA-induced chromatin modification facilitating the transcription of the downstream gene into mRNA. The second model includes the competition between the transcription into ncRNA and the binding of activator to a regulatory site of the downstream gene transcribed into mRNA. The analysis based on the mean-field kinetic equations and Monte Carlo simulations shows the likely dependences of the transcription rate on RNA polymerase concentration in situations with different rate-limiting steps. The models can also be used to scrutinize the dependence of the transcription rate on other kinetic parameters. Kinetic Monte Carlo simulations show that the first model predicts stochastic bursts in the mRNA formation provided that the transcription into ncRNA is slow, while the second model predicts in addition anti-phase stochastic bursts in the mRNA and ncRNA formation provided that that the protein attachment to and detachment from a regulatory site is slow.

INTERPLAY OF VIRAL miRNAs AND HOST mRNAs AND PROTEINS

V.P. Zhdanov

Central Eur. J. Phys., 9(5) (2011) pp. 1366-1371.

Recent experiments indicate that several viruses may encode microRNAs (miRNAs) in cells. Such RNAs may interfere with the host mRNAs and proteins. A kinetic analysis of this interplay s presented. The viral miRNA is considered to be able to associate with the host mRNA with subsequent degradation. This process may result in a decline of the mRNA population and also in a decline of the population of the protein encoded by this mRNA. With these ingredients, it was first shown the types of the corresponding steady-state kinetics in the cases of positive and negative regulation of the miRNA synthesis by the protein. In addition, the authors scrutinize the situation when the protein regulates the virion replication or, in other words, provides a feedback for the replication. For the negative feedback, the replication rate is found to increase with increasing the intracellular virion population. For the positive feedback, the replication rate first increases and then drops. These features may determine the stability of steady states.

FROM STICKING TO SLIPPING CONDITIONS IN QCM-D

V.P. Zhdanov, B. Kasemo* (*Chalmers University of Technology, Göteborg, Sweden)

Chem. Phys. Lett., 513(1-3) (2011) pp. 124-126.

Supported lipid bilayers are often studied by using quartz crystal microbalance with dissipation monitoring (QCM-D). The interpretation of the QCM-D data usually implies the no-slip boundary condition at the substrate (QCM) surface. Under certain circumstances, the oscillations of the QCM crystal may however result in the transition to slipping conditions. Employing the Frenkel-Kontorova model, the authors show that during this transition the amplitude of the bilayer vibrations drops in a stepwise fashion, i.e., the process can be classified as a first-order kinetic phase transition. The model allows also to scrutinize the corresponding changes in the force between the bilayer and support and dissipation of energy.

A KINETIC MODEL OF STANDARD SELECTIVE CATALYTIC REDUCTION OF NO BY NH3 ON SINGLE SITES

V.P. Zhdanov

React. Kinet. Mech. Catal., 103(1) (2011) pp. 11-18.

Reduction of NO by NH3 in the presence of O2 may occur on single Fe or Cu atoms or dimers incorporated into the inner walls of a zeolite. Although this process is of considerable intrinsic interest as an example of complex reactions running on single sites and is also important from the perspective of environmental chemistry, its mechanism is still open for debate. One of the likely schemes of the process implies the formation of N2 and H2O via the reaction of gas-phase NO and adsorbed NH3. The author presents a detailed analysis of the steady-state kinetics corresponding to this scheme. The model employed includes eleven elementary steps. The results obtained allow one to interpret the apparent reaction orders observed experimentally.

A KINETIC MODEL OF STANDARD SELECTIVE CATALYTIC REDUCTION OF NO BY NH3 ON TWO SITES

V.P. Zhdanov

React. Kinet. Mech. Catal., 104(2) (2011) pp. 267-272.

Reduction of NO by NH3 in the presence of O2 may occur on single Fe or Cu atoms or dimers incorporated into the inner walls of zeolite. One of the likely schemes of this reaction implies the formation of N2 and H2O through the reaction of gas-phase NO and adsorbed NH3. The steady-state kinetics corresponding to this scheme was recently analyzed by the author assuming that the reaction runs on single metal atoms. In this work, the author presents a model including two metal atoms. Under the practically important conditions, the kinetics predicted by the one- and two-site models are demonstrated to be similar. In particular, both models allow one to interpret the apparent reaction orders observed experimentally.

KINETICS OF CELL-TO-CELL SPREAD OF VIRUSES

V.P. Zhdanov

JETP Lett., 93(9) (2011) pp. 551-554.

Recent experiments indicate that many viruses can move between cells directly via the cell–cell contacts without diffusing through the extracellular environment. The first generic kinetic model is presented describing intracellular viral kinetics in combination with this mode of spread of virions. Monte Carlo simulations show the specifics of the propagation of the infection front in this case.

INTERACTION OF SINGLE VIRUS-LIKE PARTICLES WITH VESICLES CONTAINING GLYCOSPHINGOLIPIDS

M. Bally*, A. Gunnarsson*, L. Svensson**, G. Larson***, V.P. Zhdanov, F. Hook* (*Chalmers University of Technology, Göteborg, Sweden; **University of Linköping, Linköping, Sweden; ***University of Gothenburg, Göteborg, Sweden)

Phys. Rev. Lett., 107(18) (2011) 188103 (5 pp.).

Glycosphingolipids are involved in the first steps of virus-cell interaction, where they mediate specific recognition of the host cell membrane. The authors have employed total-internal-reflection fluorescence microscopy to explore the interaction kinetics between individual unlabeled noroviruslike particles, which are attached to a glycosphingolipid-containing lipid bilayer, and fluorescent vesicles containing different types and concentrations of glycosphingolipids. Under association equilibrium, the vesicle-binding rate is found to be kinetically limited, yielding information on the corresponding activation energy. The dissociation kinetics are logarithmic over a wide range of time. The latter is explained by the vesicle-size-related distribution of the dissociation activation energy. The biological, pharmaceutical, and diagnostic relevance of the study is briefly discussed.

DISSOLUTION AND REDEPOSITION ON Pt NANOPARTICLES UNDER ELECTROCHEMICAL CONDITIONS

V.P. Zhdanov, B. Kasemo* (*Chalmers University of Technology, Göteborg, Sweden)

Chem. Phys. Lett., 509(4-6) (2011) pp. 134-137.

A Schottky-type model describing Pt2+ dissolution and redeposition on Pt nanoparticles in polymer electrolyte fuel cells is presented. The charge transfer is considered to occur near the surface of nanoparticles so that the potential barrier for the reaction is formed by the double-layer potential and the image interaction. With increasing electrode potential, the transfer coefficient for dissolution is found to decrease from 0.6-0.7 down to 0.3-0.4. Its dependence on the effective dielectric constant of the double layer is appreciable while the dependence on the particle size is weak.

POTENTIAL PROFILES NEAR THE SCHOTTKY NANOCONTACTS

V.P. Zhdanov, B. Kasemo* (*Chalmers University of Technology, Göteborg, Sweden)

Physica E, 43(8) (2011) pp. 1486-1489.

The conventional Schottky model describes in the mean-field approximation the electrostatic potential appearing in a doped semiconductor during its flat contact with a metal. More recently, the Schottky model has been used to describe the mean-field potential profile near a metallic nanosphere surrounded by or located on the surface of a semiconductor. The authors present the corresponding results for a metallic nanowire. In these three cases, the shape of the potential profiles and their scalings are very different. In particular, the full width at half maximum of the potential barrier dramatically shrinks if the geometry changes from linear to cylindrical and then to spherical. In addition, the authors scrutinize the effect of the discreteness of the dopant charges on the potential near a metallic nanosphere.

Studying of Active Sites, Mechanism and Reaction Kinetics

INFLUENCE OF THE MOBILITY OF OXYGEN ON THE REACTIVITY OF La1-xSrxMnO3 PEROVSKITES IN METHANE OXIDATION

D.V. Ivanov, L.G. Pinaeva, E.M. Sadovskaya, L.A. Isupova

Kinet. Catal., 52(3) (2011) pp. 401-408.

Radically different dependences of the activity of La1-xSrxMnO3 (x = 0-0.5) perovskites in methane oxidation on the degree of substitution of strontium for lanthanum are observed for low and high temperatures. Unsubstituted LaMnO3 exhibits the highest activity in the temperature range from 300 to 500°C, while the sample with the maximum degree of substitution (La0.5Sr0.5MnO3) shows the highest activity at higher temperatures of 700–900°C. In the low temperature region, the activity of La1-xSrxMnO3 is determined by the amount of weakly bound (overstoichiometric) oxygen, which is formed in cation-deficient lattices and is characterized by a thermal desorption peak with Tmax = 705°C. At higher temperatures (800–900°C), the strongly bound oxygen of the catalyst lattice is involved in the formation of the reaction products under both unsteady- and steady-state conditions. As a consequence, the catalytic activity in methane oxidation correlates with the apparent rate constant of oxygen diffusion in the oxide bulk.

INSIGHTS INTO THE REACTIVITY OF La1-xSrxMnO3 (x = 0 ÷ 0.7) IN HIGH TEMPERATURE N2O DECOMPOSITION

D.V. Ivanov, L.G. Pinaeva, L.A. Isupova, A.N. Nadeev, I.P. Prosvirin, L.S. Dovlitova

Catal. Lett., 141(2) (2011) pp. 322-331.

In this paper a wide range of La1-xSrxMnO3 (x = 0–0.7) perovskites was synthesized by Pechini route, characterized by XRD (including high temperature measurements), XPS, differential dissolution phase analysis, TPR H2, oxygen exchange and tested in N2O decomposition at 900°C. At low degree of Sr substitution for La (x ≤ 0.3), high catalytic activity was found for perovskites with hexagonal structure (x = 0.1-0.2) and can be related to fast oxygen mobility caused by the lattice disordering during polymorphic phase transition from the hexagonal to cubic structure. For multiphase samples (x > 0.3) increase of activity and oxygen mobility can be attributed to the formation of the layer structured perovskite - LaSrMnO4 on the surface.

MECHANISM OF 1,2-DICHLOROETHANE DEHYDROCHLORINATION ON THE ACID SITES OF OXIDE CATALYSTS AS STUDIED BY IR SPECTROSCOPY

A.S. Shalygin, L.V. Malysheva, E.A. Paukshtis

Kinet. Catal., 52(2) (2011) pp. 305-315.

The adsorption of 1,2-dichloroethane on zeolite HZSM-5 and y-Al2O3 at temperatures from 25 to 400°C was studied by Fourier transform IR spectroscopy. The forms of adsorbed 1,2-dichloroethane and the products of its conversion at the Brønsted and Lewis acid sites of catalysts were identified. The kinetics of 1,2-dichloroethane conversion on the surface of catalysts was studied by in situ Fourier transform IR spectroscopy. It was demonstrated that 1,2-dichloroethane was dehydrochlorinated at the Lewis sites of y-Al2O3 even at 100°C, whereas the reaction came into play at the Brønsted sites of zeolite HZSM-5 only at 200°C. It was found that, at the Lewis acid sites of catalysts, the resulting vinyl chloride underwent oligomerization with the intermediate formation of a dimer (1,3-dichloro-2-butene), whereas the formation of 1,3-dichloro-2-butene at the Brønsted sites of zeolite HZSM-5 was not observed. The mechanisms of 1,2-dichloroethane conversions at Lewis and Brønsted acid sites were proposed.

 

EFFECT OF THE ELECTRONIC STATE AND COPPER LOCALIZATION IN ZSM-5 PORES ON PERFORMANCE IN NO SELECTIVE CATALYTIC REDUCTION BY PROPANE

O.P. Krivoruchko, T.V. Larina, R.A. Shutilov, V.Yu. Gavrilov, S.A. Yashnik, V.A. Sazonov, I.Yu. Molina, Z.R. Ismagilov

Appl. Catal., B, 103(1-2) (2011) pp. 1-10.

This study was devoted to determination of localization of the individual copper species in the pores of ZSM-5 zeolite after post-synthetic zeolite modification by incipient wetness impregnation with CuCl2 solution followed by hydrolytic polycondensation of the ions in the pores. A series of Cu(n)ZSM-5 samples, where n is the copper concentration varied from 0.5 to 5.0 wt%, were synthesized using this method. A commercial HZSM-5 zeolite having Si/Al = 17 was used for the synthesis of the catalysts. After modification the Cu(n)ZSM-5 samples were dried and calcined in air at 110 and 450°C, respectively. The samples were studied by UV–vis–NIR DR spectroscopy, XRD and by measuring and processing the low-temperature (77 K) adsorption of nitrogen and hydrogen. It was shown for the first time that at the concentration of 1.0 wt% or lower copper was localized in the form of isolated Cu2+Oh cations in the ion-exchange positions in the zeolite micro- and mesopores as well as on oxygen complexes of extraframework aluminum in thin mesopores with D < 3.2 nm in the form of superficial spinel-like structures in octahedral oxygen coordination Cu2+Oh. At the copper concentration above 1.0 wt% linear associates of weakly bound Cu2+Oh ions with unusual orbital ordering were formed in addition to the two forms discussed above. These associates existing in the forms of one- and two-dimensional nanohydroxocompounds were localized partially in the zeolite micropores but mostly in thin mesopores.

The effect of the individual copper species on the catalytic properties of Cu(n)ZSM-5 samples in selective catalytic reduction of NO by propane was also studied. It was found that isolated Cu2+Oh cations in the ion-exchange positions and Cu2+Oh cations localized on the oxygen complexes of extraframework aluminum had the highest catalytic activity in NO SCR by propane. The weakly bound linear associates of Cu2+Oh ions had lower catalytic activity, compared with isolated Cu2+Oh ions. When their amount was high, they caused steric hindrance for contact of the reagents with the more active sites. The Cu2+Oh ion associates were found to transform to nanodispersed Cu2(OH)3Cl during catalytic experiments.

LOCATION, STABILITY, AND REACTIVITY OF OXYGEN SPECIES GENERATED BY N2O DECOMPOSITION OVER Fe-ZSM-5 AND Fe-Beta ZEOLITES

V.I. Sobolev, K.Yu. Koltunov

J. Mol. Catal. A: Chem., 347(1-2) (2011) pp. 22-27.

Reactivity of oxygen species generated by N2O decomposition over Fe-ZSM-5 and Fe-Beta zeolites was investigated using oxygen isotopic exchange as test reaction. The generated species are very stable up to 300°C in the absence of the organic traces or residual N2O in the gas phase. The reactivity of the oxygen species towards organics depends on the size of the organic molecules and their ability to penetrate into the zeolite pores. For example, in case of Fe-ZSM-5 zeolite, the oxygen species react readily with toluene, but stay intact with more bulky 1,3,5-trimethylbenzene.

MoVNbTe MIXED OXIDES AS EFFICIENT CATALYST FOR SELECTIVE OXIDATION OF ETHANOL TO ACETIC ACID

V.I. Sobolev, K.Yu. Koltunov

ChemCatChem, 3(7) (2011) pp. 1143-1145.

Results from a comparative study of the catalytic activity of MoVNb, MoVTe, and MoVNbTe mixed oxides in the gas phase oxidation of ethanol are reported. Multi-component MoVNbTe mixed oxides, analogous to those, which are used in the propane (amm)oxidation), in contrast to three-component MoVNb and MoVTe oxides show exclusive efficiency in selective oxidation of ethanol by molecular oxygen to obtain acetic acid.

 

GENERATION OF REACTIVE OXYGEN SPECIES ON Au/TiO2 AFTER TREATMENT WITH HYDROGEN: TESTING THE LINK TO ETHANOL LOW-TEMPERATURE OXIDATION

V.I. Sobolev, O.A. Simakova, K.Yu. Koltunov

ChemCatChem, 3(9) (2011) pp. 1422-1425.

In the present work, the efforts were focused on the role of hydrogen in the catalytic activity of gold supported on TiO2, Al2O3, and SiO2 matrixes to provide insights into the different profiles of ethanol oxidation.

JOINT AROMATIZATION OF BUTANE AND HEXANE ON ALUMINA–PLATINUM CATALYSTS

V.V. Pashkov*, D.V. Golinsky*, I.E. Udras*, E.A. Paukshtis, A.S. Belyi* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Pet. Chem., 51(4) (2011) pp. 286-292.

It has been found that the joint aromatization of C4 and C6 alkanes proceeds during the conversion of a butane and hexane mixture on alumina–platinum catalysts. It has been shown that a necessary condition for realization of the joint aromatization is the presence of highly dispersed platinum as ionic species (Ptσ) and “hard” Lewis acid sites (Lz) of a catalyst. It has been determined that an optimum Lz/Ptσ ratio for joint conversion reaction of light alkanes is from 1 to 2.

ROLE OF DIFFERENT ACTIVE SITES IN HETEROGENEOUS ALKENE HYDROGENATION ON PLATINUM CATALYSTS REVEALED BY MEANS OF PARAHYDROGEN-INDUCED POLARIZATION

V.V. Zhivonitko*, K.V. Kovtunov*, I.E. Beck, A.B. Ayupov, V.I. Bukhtiyarov, I.V. Koptyug* (*International Tomography Center, Novosibirsk, Russia)

J. Phys. Chem. C, 115(27) (2011) pp. 13386-13391.

Substantial NMR signal enhancements provided by parahydrogen-induced polarization (PHIP) are associated with the ability of a catalyst to incorporate both H atoms of a dihydrogen molecule into the same product molecule. Therefore, PHIP can provide valuable information about the mechanisms and kinetics of catalytic hydrogenation reactions as well as produce hyperpolarized molecules for sensitivity enhancement in NMR. In this work, the PHIP technique was applied to study the structure sensitivity and the support effects on the degree of pairwise H2 addition in propene hydrogenation over supported platinum catalysts. Four series of Pt catalysts supported on Al2O3, SiO2, ZrO2, and TiO2 were examined. A nontrivial dependence of the selectivity toward pairwise H2 addition on the Pt particle size was found. Its analysis indicates that at least three types of different active sites coexist on the catalysts surface. Among them, the major one is responsible for the nonpairwise H2 addition to the double bond, whereas pairwise addition can proceed on the other two minor active sites. An explanation of the nature of these active sites is proposed. A substantial increase in the pairwise addition selectivity was found for Pt/TiO2 catalysts as compared to other catalyst series, possibly due to a strong metal―support interaction taking place even after low temperature catalyst reduction.

CHARACTERIZATION OF ACTIVE SITES OF Pd/Al2O3 MODEL CATALYSTS WITH LOW Pd CONTENT BY LUMINESCENCE, EPR AND ETHANE HYDROGENOLYSIS

A.A. Vedyagin, A.M. Volodin, V.O. Stoyanovskii, D.A. Medvedev, A.S. Noskov

Appl. Catal., B, 103(3-4) (2011) pp. 397-403.

Spectroscopic (laser-induced luminescence (LIL) and EPR) and catalytic (ethane hydrogenolysis) techniques were used for characterization of the active sites of Pd/Al2O3 catalysts. These techniques have high sensitivity and make it possible to study the catalysts with Pd concentrations as low as 0.02–0.03 wt%. It was found by EPR using spin probes that the electron donor sites of the support are modified by the deposited palladium. It was found by LIL that the Pd deposition has a substantial effect on the state of hydroxyls on the Al2O3 surface. The obtained results indicate that at Pd concentrations 0.5 wt% or lower supported Pd does not form PdO phase. Instead, it is stabilized in the form of atomically dispersed ion clusters. The possible role of the Al2O3 donor sites in stabilization of such clusters is discussed.

STRUCTURAL AND CHEMICAL STATES OF PALLADIUM IN Pd/Al2O3 CATALYSTS UNDER SELF-SUSTAINED OSCILLATIONS IN REACTION OF CO OXIDATION

E.M. Slavinskaya, O.A. Stonkus, R.V. Gulyaev, A.S. Ivanova, V.I. Zaikovsky, P.A. Kuznetsov, A.I. Boronin

Appl. Catal., A, 401(1-2) (2011) pp. 83-97.

Pd/Al2O3 supported catalysts, differed in the initial structural and chemical states of palladium, were examined for the possible existence of self-sustained oscillations in the reaction of CO oxidation under temperature-programmed and isothermal modes using plug flow reactor at ambient pressure and CO and O2 concentration of 0.2 and 1.0 vol.%, respectively. The supported samples after the action of reaction mixture were characterized using the HRTEM and XPS methods. The catalysts, calcined at relatively low temperatures 450°C, cannot induce the self-sustained oscillation phenomena in the reaction of CO oxidation. The calcination at 800°C yields highly dispersed particles of Pd0 and PdO in the catalysts with sizes varying between 2–3 and 10–20 nm, respectively. In this case self-sustained oscillations (SO) of the CO oxidation appeared in the region of middle CO conversions. In the catalyst calcined at 1000°C, PdO is formed as large particles with sizes 20–100 nm. During prolonged self-sustained oscillations under isothermal conditions with varying CO concentrations in the reaction mixture, particles with “core–shell” structures are formed, where the cores are PdO and the shells are a Pd0 clusters ordered along a specific direction due to an epitaxy on PdO. Calcination at 1200°C results in the formation of large Pd0 particles with sizes ≥200 nm. During prolonged self-sustained oscillations with varying CO concentrations under isothermal conditions, the reaction mixture causes destruction of the above particles to yield palladium particles with core–shell structures; in this case the cores are Pd0, and the shells are PdO layers.

 

LOW-TEMPERATURE OXIDATION OF CARBON MONOXIDE ON Pd(Pt)/CeO2 CATALYSTS PREPARED FROM COMPLEX SALTS

E.M. Slavinskaya, R.V. Gulyaev, O.A. Stonkus, A.V. Zadesenets*, P.E. Plyusnin*, Yu.V. Shubin*, S.V. Korenev*, A.S. Ivanova, V.I. Zaikovsky, I.G. Danilova, A.I. Boronin (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Kinet. Catal., 52(2) (2011) pp. 282-295.

Catalysts containing cerium oxide as a support and platinum and palladium as active components for the low-temperature oxidation of carbon monoxide were studied. The catalysts were synthesized in accordance with original procedures with the use of palladium and platinum complex salts. Regardless of preparation procedure, the samples prepared with the use of only platinum precursors did not exhibit activity at a low temperature because only metal and oxide (PtO, PtO2) nanoparticles were formed on the surface of CeO2. Unlike platinum, palladium can be dispersed on the surface of CeO2 to a maximum extent up to an almost an ionic (atomic) state, and it forms mixed surface phases with cerium oxide. In a mixed palladium-platinum catalyst, the ability of platinum to undergo dispersion under the action of palladium also increased; as a result, a combined surface phase with the formula PdxPtyCeO2-δ, which exhibits catalytic activity at low temperatures, was formed.

SYNERGETIC EFFECT IN PdAu/CeO2 CATALYSTS FOR THE LOW-TEMPERATURE OXIDATION OF CO

R.V. Gulyaev, L.S. Kibis, O.A. Stonkus, A.V. Zadesenets*, P.E. Plyusnin*, Yu.V. Shubin*, S.V. Korenev*, A.S. Ivanova, E.M. Slavinskaya, V.I. Zaikovsky, I.G. Danilova, A.I. Boronin (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Struct. Chem., 52(suppl.) (2011) pp. 123-136.

Gold-palladium catalysts supported on cerium oxide were synthesized with the double complex salts. X-ray photoelectron spectroscopy (XPS) and other physicochemical methods (TEM, TPR) were used to demonstrate that synthesis of highly active palladium catalysts requires the oxidative treatment stimulating the formation of a catalytically active surface solid solution PdxCe1-xO2, which is responsible for the low-temperature activity (LTA) in the reaction CO + O2. In the case of gold catalysts, active sites for the low-temperature oxidation of CO are represented by gold nanoparticles and its cationic interface species. Simultaneous deposition of two metals increases the catalyst LTA due to interaction of both gold and palladium with the support surface to form a Pd1-xCexO2 solid solution and cationic interface species of palladium and gold on the boundary of Pd-Au alloy particles anchored on the solid solution surface.

DYNAMIC Cu/Zn INTERACTION IN SiO2 SUPPORTED METHANOL SYNTHESIS CATALYSTS UNRAVELED BY in situ XAFS

D. Grandjean*,**, V.V. Pelipenko, E.D. Batyrev***, J.C. van den Heuvel***,

A.A. Khassin, T.M. Yurieva, B.M. Weckhuysen** (*Laboratory of Solid State Physics and Magnetism & INPAC, Leuven, Belgium; **Utrecht University, Utrecht, The Netherlands; ***University of Amsterdam, Amsterdam, The Netherlands)

J. Phys. Chem. C, 115(41) (2011) pp. 20175-20191.

In situ X-ray absorption spectroscopy XAFS at the Cu and Zn K-edge has been used to unravel the Cu/Zn interaction and identify the possible active site of Cu-based methanol synthesis catalysts in the Cu/ZnO/SiO2 ternary system. These highly dispersed silica supported catalysts, whose activity increases sharply as a function of the reduction temperature, were studied calcined, reduced at 200, 300, and 400°C, and for each reduction temperature under passivation/rereduction and methanol synthesis conditions. Results showed that the calcined form consists mainly of a mixed Cu/Zn hydrosilicate that is progressively transformed as the reduction temperature increases into (i) Cu metal particles, (ii) increasingly dispersed ZnO species on SiO2, and (iii) finally a Zn metallic phase forming segregated bimetallic Cu–Zn α-brass alloy particles. These different structures and Cu/Zn interfaces may correspond to different active phases and activities in methanol synthesis. After reduction at 200 and 300°C, Cu0 is likely composing most of the active phase, whereas above 300°C, the sharp increase in the number Zn0-based sites formed as a function of the reduction temperature could explain the major role played by this parameter in controlling the activity of these catalysts. The dynamic Cu/Zn interaction as a function of the temperature and gas environment

pointed out in this ternary system may be at the origin of the existence of different and sometimes contradictory models to account for the mechanisms of the methanol synthesis.

CHARACTERIZATION OF THE ACTIVE SITES ON THE SURFACE OF Al2O3 ETHANOL DEHYDRATION CATALYSTS BY EPR USING SPIN PROBES

R.A. Zotov, V.V. Molchanov, A.M. Volodin, A.F. Bedilo

J. Catal., 278(1) (2011) pp. 71-77.

Several pure and doped alumina samples were characterized by EPR using spin probes and tested in ethanol dehydration. It was found that the concentrations of the electron acceptor sites and the catalytic activity increased when alumina was modified with chlorides and sulfates. Meanwhile, the number of the electron donor sites decreased. A very good correlation between the concentration of the weak acceptor sites and the catalytic activity of the acid-modified catalysts almost passing through the origin of the coordinates was obtained for all the studied samples. Alumina poisoning with sodium resulted in the decrease in the catalytic activity and the concentration of the weak acceptor sites. Therefore, it appears that the weak acceptor sites tested using anthracene are related to the sites active in the ethanol dehydration reaction.

INVESTIGATION OF OXYGEN STATES AND REACTIVITIES ON A NANOSTRUCTURED CUPRIC OXIDE SURFACE

D.A. Svintsitskiy, A.I. Stadnichenko, D.V. Demidov, S.V. Koshcheev, A.I. Boronin

Appl. Surf. Sci., 257(20) (2011) pp. 8542-8549.

Nanostructured copper (II) oxide was formed on clean copper foil at room temperature using activated oxygen produced by RF discharge. CuO particles of approximately 10-20 nm were observed on the surface by Scanning Tunneling Microscopy (STM). The copper states and oxygen species of the model cupric oxide were studied by means of X-ray Photoelectron Spectroscopy (XPS). These oxide particles demonstrated abnormally high reactivity with carbon monoxide (CO) at temperatures below 100°C. The XPS data showed that the interaction of CO with the nanostructured cupric oxide resulted in reduction of the CuO particles to Cu2O species. The reactivity of the nanostructured cupric oxide to CO was studied at 80°C using XPS in step-by-step mode. The initial reactivity was estimated to be 5 x 10-5 and was steadily reduced down to 5 x 10-9 as the exposure was increased. O1s spectral analysis allowed to propose that the high initial reactivity was caused by the presence of non-lattice oxygen states on the surface of the nanostructured CuO. It was established that reoxidation of the partially reduced nanostructured cupric oxide by molecular oxygen O2 restored the highly reactive oxygen form on the surface. These results allowed to propose that the nanostructured cupric oxide could be used for low temperature catalytic CO oxidation. Some hypotheses concerning the nature of the non-lattice oxygen species with high reactivity are also discussed.

Fe-CONTAINING NICKEL PHOSPHATE MOLECULAR SIEVES AS HETEROGENEOUS CATALYSTS FOR PHENOL OXIDATION AND HYDROXYLATION WITH H2O2

M.N. Timofeeva, Z. Hasan*, A.Yu. Orlov, V.N. Panchenko, Yu.A. Chesalov, I.E. Soshnikov, Sung H. Jhung* (*Kyungpook National University, Taegu, South Korea)

Appl. Catal., B, 107(1-2) (2011) pp. 197-204.

Fe-containing nickel phosphate molecular sieves (Fe-VSB-5) were hydrothermally synthesized in weak basic conditions under microwave irradiation and characterized by SEM, XRD,

N2-adsorption/desorption, DRS-UV–vis, and FT-IR spectroscopy using PhCN and CDCl3 as probe molecules. The catalytic activity of Fe-VSB-5 was tested for the phenol hydroxylation and wet phenol oxidation with H2O2. The increase in iron content in Fe-VSB-5 leds to an increase in the reaction rates. The increases in activity can be explained by the role of the Fe species, which increases the generation of radicals. The Fe-VSB-5 samples were stable against the leaching out of Fe ions. The catalytic activity of Fe-VSB-5 was compared to the catalytic activity of traditional Fe-containing materials.

CATALYTIC ROLE OF O•– RADICALS IN THE LOW-TEMPERATURE ISOTOPIC EXCHANGE IN DIOXYGEN

E.V. Starokon, M.V. Parfenov, S.E. Malykhin, G.I. Panov

J. Phys. Chem. C, 115(25) (2011) pp. 12554-12559.

In spite of a long investigation history, the low-temperature isotopic exchange in dioxygen taking place without involvement of the catalyst oxygen (R0 exchange) is still an exotic and poorly understood phenomenon in heterogeneous catalysis. Although very strong bonds are to be cleft in O2 molecules (118 kcal/mol), over some metal oxides R0 can be observed even at the temperature of liquid nitrogen. In this work, the authors studied the R0 exchange over a FeZSM-5 zeolite at 233 K and discovered for the first time a linear dependence of the R0 rate on the concentration of O•– radicals (a-oxygen), which identifies a catalytic role of these species. Upon transition to cryogenic temperatures, O•– species lose the ability to exchange themselves with dioxygen, but start functioning as a principal part of unique active sites capable of catalyzing a very smooth redistribution of the oxygen-oxygen bonds in adsorbed O2 molecules. Running by a highly concerted mechanism, this remarkable process leads to the R0 exchange with almost zero activation energy (0.2 kcal/mol). The catalytic role of O•– radicals well explains all previous results obtained for the R0 exchange in the literature. Possible models of active sites comprising O•– species are discussed.

ROOM-TEMPERATURE OXIDATION OF METHANE BY a-OXYGEN AND EXTRACTION OF PRODUCTS FROM THE FeZSM-5 SURFACE

E.V. Starokon, M.V. Parfenov, L.V. Piryutko, S.I. Abornev, G.I. Panov

J. Phys. Chem. C, 115(5) (2011) pp. 2155-2161.

Room-temperature oxidation of methane to methanol by a-oxygen is of great mechanistic interest for both conventional and biomimetic oxidation catalysis. This work was carried out using new-generation FeZSM-5 samples that have the Oa concentration of 100 umol/g. This value exceeds 3-15 times the Oa concentration on the earlier studied samples, thus providing more precise quantitative measurements related to the reaction mechanism. Fourier transform infrared spectroscopy data confirmed an earlier conclusion that CH4 + Oα surface reaction proceeds by the hydrogen abstraction mechanism. This mechanism leads to hydroxy and methoxy groups residing on α-sites. The methanol formation takes place by hydrolysis of (Fe-OCH3)α groups at the step of extraction. For the first time dimethyl ether (DME) was identified in the reaction products, its amount comprising 6-7% of the methane reacted. In distinction to methanol, DME is readily extracted both by dry solvents (acetonitrile, tetrahydrofuran, ethanol) and their mixtures with water. A reliable extraction procedure was developed, which provides a 75% recovery of the methane oxidation products (methanol + DME). The missing products are shown to remain on the catalyst surface and can be quantitatively recovered in the form of COx at heating the sample. A mechanism involving CH3radicals formed in the H-abstraction step is suggested to explain the reaction stoichiometry CH4:Oα = 1:1.75 and a deficit of the carbon balance at extraction.

KINETICS AND MECHANISM OF THE HOMOGENEOUS OXIDATION OF n-BUTENES TO METHYL ETHYL KETONE IN A SOLUTION OF Mo-V-PHOSPHORIC HETEROPOLY ACID IN THE PRESENCE OF PALLADIUM

PYRIDINE-2,6-DICARBOXYLATE

V.F. Odyakov, E.G. Zhizhina

Kinet. Catal., 52(6) (2011) pp. 828-834.

In catalytic two-step n-butene oxidation with dioxygen to methyl ethyl ketone, the first step is the oxidation of n-C4H8 with an aqueous solution of Mo–V–P heteropoly acid in the presence of Pd(II) complexes. The kinetics of n-butene oxidation with solutions of H7PV4Mo8O40 (HPA-4) in the presence of the Pd(II) dipicolinate complex (H2O)PdII(dipic) (I), where dipic2– is the tridentate ligand 2,6-NC5H3(COO)2, is studied. Calculation shows that, at the ratio dipic2– : Pd(II) = 1 : 1, the ligand decreases the redox potential of the Pd(II)/Pdmet system from 0.92 to 0.73–0.77, due to which Pd(II) is stabilized in reduced solutions of HPA-4. The reaction is first-order with respect to n-C4H8. Its order with respect to Pd(II) is slightly below unity, and its order with respect to HPA-4 is relatively low (~0.63). The activation energy of but-1-ene oxidation in the temperature range from 40 to 80°C is 49.0 kJ/mol, and that of the oxidation of but-2-ene is 55.6 kJ/mol. The mechanism of the reaction involving the cis-diaqua complex [(H2O)2PdII(Hdipic)]+, which forms reversibly from complex I, is proposed. The reaction rate is shown to increase with an increase in the HPA-4 concentration due to an increase in the acidity of the solution.

PARTIAL OXIDATION OF METHANE ON Pt-SUPPORTED LANTHANIDE DOPED CERIA–ZIRCONIA OXIDES: EFFECT OF THE SURFACE/LATTICE OXYGEN MOBILITY ON CATALYTIC PERFORMANCE

V.A. Sadykov, N.N. Sazonova, A.S. Bobin, V.S. Muzykantov, E.L. Gubanova*, G.M. Alikina, A.I. Lukashevich, V.A. Rogov, E.N. Ermakova, E.M. Sadovskaya, N.V. Mezentseva, E.G. Zevak, S.A. Veniaminov, M. Muhler*, C. Mirodatos**, Y. Schuurman**, A.C. van Veen*,** (*Ruhr-Universität Bochum, Bochum, Germany; **Institut de Recherches sur la Catalyse et L’environnement de Lyon, Villeurbanne Cedex, France)

Catal. Today, 169(1) (2011) pp. 125-137.

Partial oxidation of methane into syngas at short contact times (5–15 ms) was studied in both steady-state and transient modes at temperatures up to 850°C in realistic feeds (CH4 content up to 20%, CH4/O2 = 2) with a minimum impact of mass and heat transfer for structured catalysts carrying Pt/Ln0.3Ce0.35Zr0.35O2-y (Ln = La, Pr, Gd) as thin layers on walls of corundum channel substrates. Oxygen mobility and reactivity of the active phase were characterized by oxygen isotope heteroexchange, temperature-programmed O2 desorption and CH4 reduction, isothermal pulse reduction by methane with wide variation of CH4 concentrations and TAP pulse studies. Experimental data point towards a selective oxidation of methane into syngas via a direct route with oxygen-assisted methane activation. This mechanistic feature is related to the strong Pt-support interaction stabilizing highly dispersed oxidic Pt species less active in CH4 and syngas combustion than metallic Pt clusters. Support activates O2 molecules and supplies active oxygen species to Pt sites. A high rate of oxygen diffusion on the surface and in the bulk of the support and Pt-support oxygen spillover stabilizes Pt in a well dispersed partially oxidized state while preventing coking at high concentrations of CH4 in the feed.

DRY REFORMING OF METHANE OVER Pt/PrCeZrO CATALYST: KINETIC AND MECHANISTIC FEATURES BY TRANSIENT STUDIES AND THEIR MODELING

V.A. Sadykov, E.L. Gubanova, N.N. Sazonova, S.A. Pokrovskaya, N.A. Chumakova, N.V. Mezentseva, A.S. Bobin, R.V. Gulyaev, A.V. Ishchenko, T.A. Krieger, C. Mirodatos*

(*Institut de Recherches sur la Catalyse et L’environnement de Lyon, Villeurbanne Cedex, France)

Catal. Today, 171(1) (2011) pp. 140-149.

The effect of pretreatment and Pt content on the catalytic properties as well as mechanistic features of DR were investigated for structured catalysts comprised of Pt supported on CeO2-ZrO2 oxide doped by Pr. Progressive reduction of cationic Pt species by the reaction feed lowers the activity in CH4 dry reforming while accelerating the reverse water gas shift reaction catalyzed only by Pt(0), which then decreases progressively the H2/CO ratio in the effluent. This process is counteracted by the mobility of surface oxygen supplying oxygen atoms to reduced Pt centers thus ensuring their reoxidation and generating in parallel surface oxygen vacancies for the dissociation of CO2.

A mathematical model and software were developed for numerically studying the transients of the complex catalytic reactions. The processing of experimental data was fulfilled taking into account the importance of cationic forms of Pt, reactivity of carbonate complexes coordinated to these cations and oxygen surface/bulk diffusion. A quantitative evaluation of the density of catalyst's active sites and their coverage by reactive species was accomplished and the rates both of the lattice oxygen diffusion and main stages of the catalytic reaction were estimated.

DRY REFORMING OF METHANE OVER LnFe0.7Ni0.3O3-δ PEROVSKITES: INFLUENCE OF Ln NATURE

L.G. Kapokova, S.N. Pavlova, R.V. Bunina, G.M. Alikina, T.A. Krieger, A.V. Ishchenko, V.A. Rogov, V.A. Sadykov

Catal. Today, 164(1) (2011) pp. 227-233.

LnFe0.7Ni0.3O3-δ (Ln = La, Pr, Sm) perovskites synthesized via Pechini method have been studied as catalysts of methane dry reforming (MDR). Effects of pretreatment and type of Ln cation on the structural and redox properties of perovskites and their catalytic performance have been elucidated. The most active catalysts are obtained by keeping perovskites in the reaction feed at high temperatures due to the formation of Ni–Fe alloy particles released from the perovskite lattice and stabilized on its surface. PrFe0.7Ni0.3O3-δ was found to be the most active and stable catalyst due to the optimal composition of segregated Ni–Fe alloy particles and redox properties of oxide matrix.

FORMATION OF PLATINUM SITES ON LAYERED DOUBLE HYDROXIDES TYPE BASIC SUPPORTS: I. EFFECT OF THE NATURE OF THE INTERLAYER ANION ON THE STRUCTURE CHARACTERISTICS OF THE LAYERED ALUMINUM–MAGNESIUM HYDROXIDE AND THE FORMATION OF AN OXIDE PHASE

O.B. Belskaya*,**, N.N. Leont’eva*, T.I. Gulyaeva*, V.A. Drozdov*,**, V.P. Doronin*,**, V.I. Zaikovsky, V.A. Likholobov* (*Institute of Hydrocarbons

Processing, Omsk, Russia; **Omsk State Technical University, Omsk, Russia)

Kinet. Catal., 52(5) (2011) pp. 761-769.

A layered aluminum–magnesium hydroxide of the hydrotalcite type containing interlayer carbonate counterions (HT-CO3) and activated hydrotalcite containing interlayer OH ions (HT-OH) were studied for the subsequent use as the precursors of supports for platinum catalysts. It was found that the nature of an interlayer anion in the composition of an aluminum–magnesium layered hydroxide is an important factor affecting both the formation of the oxide support and its texture characteristics. The replacement of the interlayer anion by OH resulted in changes in the structural parameters of the initial double hydroxide: a decrease in the interlayer distance with the retention of the Mg/Al ratio and an increase in the imperfection of the layered material. X-ray diffraction studies in the temperature range of 30– 900°C showed that HT-OH is characterized by the ability to form low-temperature spinel at 375°C. As a result, two types of aluminum–magnesium oxide supports, which were characterized by different pore space organizations at the same Mg : Al ratio, were obtained from the given layered hydroxides.

HYDROISOMERIZATION OF BENZENE-CONTAINING GASOLINE FRACTIONS ON A Pt/SO42-–ZrO2–Al2O3 CATALYST: II. EFFECT OF CHEMICAL COMPOSITION ON ACIDIC AND HYDROGENATING AND THE OCCURRENCE OF MODEL ISOMERIZATION REACTIONS

M.O. Kazakov*, A.V. Lavrenov*, I.G. Danilova, O.B. Belskaya*, V.K. Duplyakin* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Kinet. Catal., 52(4) (2011) pp. 573-578.

The acidic and hydrogenating of Pt/SO42-–ZrO2–Al2O3 samples containing from 18.8 to 67.8 wt% Al2O3 as a support constituent were studied by the IR spectroscopy of adsorbed CO and pyridine, and the model reactions of n-heptane and cyclohexane isomerization on these catalysts were examined. The total catalyst activity in the conversion of n-heptane decreased with the concentration of Al2O3; this manifested itself in an increase in the temperature of 50% n-heptane conversion from 112 to 266°C and in an increase in the selectivity of isomerization to 94.2%. In this case, the maximum yield of isoheptanes was 47.1 wt%, which was reached on a sample whose support contained 67.8 wt% Al2O3. A maximum yield (69.6 wt%) and selectivity (93.7%) for methylcyclopentane formation from cyclohexane were also reached on the above catalyst sample. This can be explained by lower concentrations of Lewis and Bronsted acid sites in the Pt/SO42-–ZrO2–Al2O3 system, as compared with those in Pt/SO42-–ZrO2. The experimental results allowed to make a preliminary conclusion that the Pt/SO42-–ZrO2–Al2O3 catalyst whose support contains 67.8 wt% Al2O3 is promising for use in the selective hydroisomerization of benzene-containing gasoline fractions in the thermodynamically favorable process temperature range of 250–300°C.

FORMATION OF PLATINUM SITES ON LAYERED DOUBLE HYDROXIDE TYPE BASIC SUPPORTS: II. EFFECT OF THE NATURE OF THE INTERLAYER ANION OF THE LAYERED ALUMINUM-MAGNESIUM HYDROXIDES ON PLATINUM BINDING AND Pt/MgAlOx FORMATION

O.B. Belskaya*, T.I. Gulyaeva*, N.N. Leont’eva*, V.I. Zaikovsky, T.V. Larina, T.V. Kireeva*, V.P. Doronin*, V.A. Likholobov* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Kinet. Catal., 52(6) (2011) pp. 876-885.

The interaction of aqueous H2PtCl6 solutions with hydrotalcite-type aluminum–magnesium

hydroxides differing in the nature of their interlayer anion is reported. In the case of CO32- as the interlayer anion, the introduction of the platinum(IV) chloro complex does exerts no significant effect on the structural properties of the support, on its thermal decomposition dynamics, and on the textural characteristics of the resulting oxide phase. The binding of the platinum complexes to “activated hydrotalcite” with interlayer OH anions increases the interplanar spacing and enhances the thermal stability of the layered structure. This is accompanied by marked changes in textural characteristics of the material, leading to the formation of a nearly monodisperse mixed oxide phase. In the Pt/MgAlOx samples obtained by reductive treatment, a considerable proportion of platinum is in the form of planar particles, and this corroborates the hypothesis that the metal complex at the sorption stage is mainly localized in the interlayer space of this support. Platinum binds to the support as chloro complexes via rapid anion exchange, and these bound platinum species are characterized by a higher reduction temperature.

COBALT OXIDE CATALYST FOR HYDROLYSIS OF SODIUM BOROHYDRIDE AND AMMONIA BORANE

V.I. Simagina, O.V. Komova, A.M. Ozerova, O.V. Netskina, G.V. Odegova, D.G. Kellerman*, O.A. Bulavchenko, A.V. Ishchenko (*Institute of Solid State Chemistry, Yekaterinburg, Russia)

Appl. Catal., A, 394(1-2) (2011) pp. 86-92.

The catalytic properties of Co3O4 in NaBH4 and NH3BH3 hydrolysis have been studied. Experiments were carried out at 20–40°C using 0.12 M hydride solution. According to magnetic susceptibility measurements, FTIR, XRD, and TEM studies, Co3O4 is reduced to the ferromagnetic catalytically active Co2B phase under the action of the NaBH4 hydrolysis reaction medium. A correlation was found between the content of the cobalt boride phase formed in situ and catalyst activity. The reduction of Co3O4 in NH3BH3 proceeds at slower rate than in NaBH4. The addition to a solution of NH3BH3 of even a small amount of NaBH4 increases considerably the reduction rate of Co3O4. Using a Co3O4-based precursor instead of the widely used CoCl2 leads to the formation of a stable catalytically active phase of cobalt boride.

LOW-TEMPERATURE DECOMPOSITION OF AMMONIA BORANE IN THE PRESENCE OF TITANIA

O.V. Komova, V.I. Simagina, G.V. Odegova, Yu.A. Chesalov, O.V. Netskina, A.M. Ozerova

Inorg. Mater., 47(10) (2011) pp. 1101-1107.

In the presence of anatase, the thermal decomposition of ammonia borane (AB) begins at a lower temperature, which enables AB dehydrogenation at a temperature as low as 80°C. The reduction in the AB decomposition temperature depends on the AB content of the mixture. In situ IR spectroscopy data demonstrate that, in the presence of TiO2, the structural destabilization of AB occurs during heating and is accompanied by the formation of an oxygen-containing boron phase and partial reduction of the titania, which is supported by diffuse reflectance spectroscopy data.

EFFECT OF THE REACTION MEDIUM ON THE STRUCTURE OF THE La1-xCaxMnO3 (x = 0–1) SOLID SOLUTIONS PREPARED BY THE PECHINI METHOD

L.A. Isupova, E.Yu. Gerasimov, V.I. Zaikovsky, S.V. Tsybulya

Kinet. Catal., 52(1) (2011) pp. 104-110.

The phase composition and microstructure of La1-xCaxMnO3 (x = 0–1) materials prepared by the Pechini method from polymer-salt stocks were studied after testing these materials in methane oxidation. According to X-ray diffraction data, the reaction medium causes no significant changes in the samples, while high-resolution transmission electron microscopy indicates that the x > 0.3 samples are

unstable. Under the action of the reaction medium, the perovskite structure of these samples undergoes partial decomposition accompanied by the formation of planar defects having a lower manganese content. The number and degree of segregation of these defects increase with increasing calcium content. The calcium oxide and manganese oxide phases as segregated nanoparticles are observed on the particle surface. These changes are caused by the decrease in the oxygen content of the manganites under the action of the reaction medium (T, PO2), by the formation of vacancies, and by the variation of the charge of the manganese cations, as well as by the charge ordering tendency of the manganese cations. Therefore, the observed changes in catalytic activity under the action of the reaction medium for x > 0.3 can be due to perovskite decomposition accompanied by the formation of planar defects, the release of the manganese oxide and calcium oxide phases, and their subsequent sintering.

INTERACTION OF HYDROGEN AND WATER WITH OXYGEN ADSORBED ON SILVER

E.V. Dokuchits, A.V. Khasin, A.A. Khassin

React. Kinet. Mech. Catal., 103(2) (2011) pp. 261-266.

The identity of surface silver hydroxides produced by hydrogenation or hydration of surface silver oxide was demonstrated. A two-route mechanism of hydrogen interaction with oxygen adsorbed on silver was suggested. The first route includes two consecutive-parallel steps: formation of adsorbed hydroxyl groups and their interaction with hydrogen; the second route consists of two consecutive steps: formation of adsorbed hydroxyl groups and their disproportionation yielding water and adsorbed oxygen.

COMPOSITION AND PROPERTIES OF FUNCTIONAL GROUPS ON SURFACE OF CARBON SORBENTS MODIFIED BY AMINOCAPROIC ACID

V.A. Likholobov*, L.G. P’yanova*, A.I. Boronin, S.V. Koshcheev, A.N. Salanov, O.N. Baklanova*, O.A. Knyazheva*, A.V. Veselovskaya* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Prot. Met. Phys. Chem. Surf., 47(2) (2011) pp. 181-190.

The composition and properties of functional groups on the surface of carbon sorbents modified with aqueous solutions of aminocaproic acid of different concentrations were studied using physicochemical analysis methods including: acid-base titration, the Kjeldahl method, scanning electron microscopy, X-ray microanalysis, and X-ray photoelectron spectroscopy. The initial carbon sorbent was shown to have almost no functional groups on its surface. It was ascertained that the surface functionalization of carbon sorbent results in a change in microstructure and an increase in the amount of oxygen- and nitrogen-containing groups with increasing concentration of the modifying agent followed by its further polycondensation on the surface. According to the XPS data, the formation of the bond between aminocaproic acid and the carbon surface of sorbents occurs via a carboxylic group.

IDENTIFICATION OF NITROGEN-CONTAINING SPECIES OBTAINED BY NITRIC OXIDE ADSORPTION ON THE SURFACE OF MODEL GOLD CATALYSTS

A.V. Bukhtiyarov, A.V. Nartova, R.I. Kvon

Kinet. Catal., 52(5) (2011) pp. 756-760.

Nitric oxide adsorption at 300–500 K on gold particles supported on an alumina film has been investigated for the first time by in situ X-ray photoelectron spectroscopy. Two nitrogen-containing adsorption species can form on the surface of gold particles. By test experiments on NO adsorption on the stepped face (533) of a gold single crystal, these species have been identified as adsorbed nitrogen atoms (which are detected throughout the temperature range examined) and a surface complex with N2O stoichiometry (which is stable in a narrow temperature range of 325–425 K).

AN XPS AND STM STUDY OF THE SIZE EFFECT IN NO ADSORPTION ON GOLD NANOPARTICLES

A.V. Bukhtiyarov, A.V. Nartova, R.I. Kvon, V.I. Bukhtiyarov

Russ. Chem. Bull., 60(10) (2011) pp. 1977-1984.

The effect of the gold particle size, temperature of the model gold catalyst, and NO pressure on the composition of the adsorption layer was studied by in situ XPS and STM methods. Adsorption of nitric oxide was carried out on gold nanoparticles with a mean size of 2–7 nm prepared on the thin film surface of alumina. In high-vacuum conditions (P NO ≈ 10-5 Pa), only atomically adsorbed nitrogen is formed on the surface of gold nanoparticles. At about 1 Pa pressure of NO and in the temperature range from 325 to 475 K, atomically adsorbed nitrogen coexists with the N2O adsorption complex. The surface concentration of the adsorbed species changes with a change in both the mean gold particle size and adsorption temperature. The saturation coverage of the surface with the nitrogen-containing complexes is observed for the sample with a mean size of gold particles of 4 nm. The surface of these samples is mainly covered with atomically adsorbed nitrogen, the saturation coverage of adsorbed nitrogen of about ∼0.6 monolayer is attained at T = 473 K. The change in the composition of the adsorption layer with temperature of the catalysts agrees with the literature data on the corresponding temperature dependence of the selectivity of N2 formation observed in the catalytic reduction of NO with carbon monoxide on the Au/Al2O3 catalyst. The dependences of the composition of the adsorption layer on the mean size of Au nanoparticles (size effect) and temperature of the catalyst are explained by the sensitivity of NO adsorption to specific features of the gold surface.

MECHANISM OF H2-PROMOTED OXIDATION OF NITROGEN MONOXIDE OVER Ag/Al2O3

N.A. Sadokhina*, A.V. Bukhtiyarov, A.I. Mytareva*, R.I. Kvon, V.I. Bukhtiyarov, A.Yu. Stakheev* (*Zelinsky Institute of Organic Chemistry, Moscow, Russia)

Mendeleev Commun., 21(5) 2011 pp. 274-276.

H2-promoted oxidation of NO to NO2 over Ag/Al2O3 proceeds via two-step echanism:

(1) formation of surface nitrate species, and

(2) reduction of this species with NO. Hydrogen plays a crucial role at the first step.

H2-INDUCED NOx ADSORPTION/ DESORPTION OVER Ag/Al2O3: TRANSIENT EXPERIMENTS AND TPD STUDY

N.A. Sadokhina*, D.E. Doronkin*, P.V. Pributkov*, V.I. Bukhtiyarov, R.I. Kvon, A.Yu. Stakheev* (*Zelinsky Institute of Organic Chemistry, Moscow, Russia)

Top. Catal., 54(16-18) (2011) pp. 1190-1196.

NO adsorption/desorption over 1 wt% Ag/Al2O3 was studied by a combination of isothermal transient adsorption/desorption and NOx temperature-programmed desorption (NOx-TPD) methods. NOx-TPD profiles obtained for Ag/Al2O3 were identified by comparison with decomposition profiles of “model” AgNO3/Al2O3 and Al(NO3)3/Al2O3 prepared by impregnation of Al2O3 with individual AgNO3 and Al(NO3)3 compounds. The data obtained indicate that H2-induced NO adsorption leads to the formation of surface Ag and Al-nitrates. Their accumulation on the catalyst surface is accompanied by an intensive NO2 evolution, which proceeds primarily via reaction of surface nitrates with NO. Thus, NO2 formation appears to result from an intrinsic stage of the H2-induced NOx adsorption process, rather than from the direct oxidation of NO by gaseous oxygen catalyzed by Ag.

CONCENTRATION HYSTERESIS IN METHANE OXIDATION ON NANOSIZED PLATINUM PARTICLES

I.Yu. Pakharukov, I.E. Beck, M.M. Matrosova, V.I. Bukhtiyarov, V.N. Parmon

Doklady Phys. Chem., 439(1) (2011) pp. 131–134.

Study of hysteresis is an efficient tool for investigating the catalytic process mechanism. In the work it was for the first time detected the concentration hysteresis in low-temperature methane oxidation on a dispersed Pt/γ-Al2O3 catalyst with an average platinum particle size of 2 nm.

 

GAS PHASE NITRIDATION OF SILICATE FIBER GLASS MATERIALS WITH AMMONIA: THREE CASE STUDIES

Yu.K. Gulyaeva, A.P. Suknev, E.A. Paukshtis, B.S. Bal’zhinimaev,

J. Non-Cryst. Solids, 357(18) (2011) pp. 3338-3344.

Three types of the leached fiber glass materials of silicate origin modified with Zr, Al and rare earth metals (REM) were nitridated with ammonia at temperatures ranging from 673 to 973 K. DRIFTS (Diffuse Reflectance Infrared Fourier-Transform Spectroscopy) and H/D exchange using ND3 were applied for characterization of the formed NH species. Along with nitridation of silanol groups their dehydroxylation as well as hydrolysis of NHx species take place. In situ DRIFTS study showed that the limiting steps are slow chemical reactions, but not a diffusion of NH3 or H2O molecules in the bulk of glasses. The concept on strained siloxane bridges formed due to dehydroxylation of two adjacent silanol groups was used for explanation of the reaction kinetics features.

CARBONYLATION OF DIMETHYL ETHER ON SOLID Rh-PROMOTED Cs-SALT OF KEGGIN 12-H3PW12O40: A SOLID-STATE NMR STUDY OF THE REACTION MECHANISM

M.V. Luzgin, M.S. Kazantsev, G.G. Volkova, W. Wang*, A.G. Stepanov (*Lanzhou University, Gansu, PR China)

J. Catal., 277(1) (2011) pp. 72-79.

The carbonylation of dimethyl ether (DME) with carbon monoxide on Rh-promoted cesium salt of 12-tungstophosphoric acid, Rh/Cs2HPW12O40 (HPA), has been studied with 13C solid-state NMR. The bi-functional character of Rh/Cs2HPW12O40 catalyst in halide-free carbonylation of DME has been directly demonstrated. The activation of the C–O bond of DME proceeds on Brønsted acid sites of HPA with the formation of the methyl group attached to the surface of HPA (methoxy species), whereas the role of rhodium consists in trapping carbon monoxide from gaseous phase and a transfer of CO to the center of DME activation, acidic OH-group of the catalyst, in the form of rhodium carbonyls. The lattice of Cs2HPW12O40 makes it possible to locate these two different active centers in close proximity to each other, e.g., on two adjacent oxygen atoms, terminal and bridging, of one Keggin anion, thus facilitating the insertion of carbon monoxide from rhodium carbonyl into the C–O bond of methoxy-group to produce the acetate group bound to the Keggin anion. The latter offers finally methyl acetate under the interaction with DME, the intermediate surface methoxy-groups being restored.

HYDROGEN H/D EXCHANGE AND ACTIVATION OF C1-n-C4 ALKANES ON Ga-MODIFIED ZEOLITE BEA STUDIED WITH 1H MAGIC ANGLE SPINNING NUCLEAR MAGNETIC RESONANCE in situ

A.A. Gabrienko, S.S. Arzumanov, A.V. Toktarev, D. Freude*, J. Haase*, A.G. Stepanov (*University of Leipzig, Leipzig, Germany)

J. Phys. Chem., 115(28) (2011) pp. 13877-13886.

Kinetics of H/D hydrogen exchange between C1-n-C4 alkanes and Bronsted acid sites (BAS) of both the pure acid-form zeolite BRA (H-BRA) and Ga-modified zeolite BRA (Ga/H-BEA) was monitored by 1H MAS NMR spectroscopy in situ at 423-563 K. Comparative analysis of the rates of the exchange for H-BRA and Ga/H-BRA zeolites reveals a remarkable increase of the rate by 1-2 orders of magnitude, decrease of activation energy, and an appearance of regioselectivity of the exchange into the methyl groups of C3-n-C4 alkanes upon modification of H-BEA zeolite with gallium. These data identify an evident promoting effect of Ga on activation of alkane C-H bonds by BAS. The effect has been rationalized by preliminary dissociative adsorption of alkanes on gallium(III) oxide species inside zeolite pores to form gallium-alkyl species, which are further involved in the exchange with neighbor BAS. Involvement of both BAS and Ga species in alkane activation accounts for earlier suggested synergistic effect (Buckles, G., et al. Catal. Lett. 1991, 11, 89) of both BAS and gallium species in alkane activation and aromatization on Ga-modified high silica zeolites.

 

CATALYTIC ENANTIOSELECTIVE OXIDATION OF BULKY ALKYL ARYL THIOETHERS WITH H2O2 OVER TITANIUM-SALAN CATALYSTS

K.P. Brylyakov, E.P. Talsi

Eur. J. Org. Chem., 24 (2011) pp. 4693-4698.

A simple and efficient catalytic procedure for the oxidation of bulky (preferably aryl benzyl substituted) thioethers with hydrogen peroxide in good to high yields and enantioselectivities (up to 98.5 % ee) is reported. The high optical yields are achieved in a tandem stereoconvergent enantioselective oxidation and kinetic resolution process. A reasonable balance between the sulfoxide yield and enantioselectivity could be found by varying the concentration and temperature. An improved synthesis of the titanium-salan catalysts for the preparation of a more stereoselective catalyst is reported.

NON-HEME MANGANESE COMPLEXES CATALYZED ASYMMETRIC EPOXIDATION OF OLEFINS BY PERACETIC ACID AND HYDROGEN PEROXIDE

R.V. Ottenbacher, K.P. Brylyakov, E.P. Talsi

Adv. Synth. Catal., 353(6) (2011) pp. 885-889.

Chiral non-heme aminopyridine manganese complexes catalyze the enantioselective epoxidation of olefins with peracetic acid or hydrogen peroxide with moderate to high yields and ee values up to 89% (peracetic acid, AcOOH) and 84% (hydrogen peroxide, H2O2), performing as many as 1000 turnovers.

EPR, 1H AND 2H NMR, AND REACTIVITY STUDIES OF THE IRON–OXYGEN INTERMEDIATES IN BIOINSPIRED CATALYST SYSTEMS

O.Yu. Lyakin, K.P. Brylyakov, E.P. Talsi

Inorg. Chem., 50(12) (2011) pp. 5526–5538.

Complexes [(BPMEN)FeII(CH3CN)2](ClO4)2 (1, BPMEN = N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)-1,2-diaminoethane) and [(TPA)FeII(CH3CN)2](ClO4)2

(2, TPA = tris(2-pyridylmethyl)amine) are among the best nonheme iron-based catalysts for bioinspired oxidation of hydrocarbons. Using EPR and 1H and 2H NMR spectroscopy, the iron–oxygen intermediates formed in the catalyst systems 1,2/H2O2; 1,2/H2O2/CH3COOH; 1,2/CH3CO3H; 1,2/m-CPBA; 1,2/PhIO; 1,2/tBuOOH; and 1,2/tBuOOH/CH3COOH have been studied (m-CPBA is m-chloroperbenzoic acid). The following intermediates have been observed: [(L)FeIII(OOR)(S)]2+, [(L)FeIV═O(S)]2+ (L = BPMEN or TPA, R = H or tBu, S = CH3CN or H2O), and the iron–oxygen species 1c (L = BPMEN) and 2c (L = TPA). It has been shown that 1c and 2c directly react with cyclohexene to yield cyclohexene oxide, whereas [(L)FeIV═O(S)]2+ react with cyclohexene to yield mainly products of allylic oxidation. [(L)FeIII(OOR)(S)]2+ are inert in this reaction. The analysis of EPR and reactivity data shows that only those catalyst systems which display EPR spectra of 1c and 2c are able to selectively epoxidize cyclohexene, thus bearing strong evidence in favor of the key role of 1c and 2c in selective epoxidation. 1c and 2c were tentatively assigned to the oxoiron(V) intermediates.

HOMOCHIRAL POROUS METAL-ORGANIC FRAMEWORKS: A STEP TO THE FUTURE OF STEREOSELECTIVE RECOGNITION AND CATALYSIS

K.P. Brylyakov, E.P. Talsi

In “Chemical Physics Research and Developments”, Nova Science Publishers, NY, 2011, pp. 47-59.

In this commentary, the authors present an overview of known homochiral metal-organic materials capable of stereoselective recognition, sorption and separation of guest molecules and those promoting asymmetric catalytic processes inside the chiral pores.

ELECTRICAL CONDUCTIVITY OF MAGNESIUM OXIDE AS A CATALYST FOR RADICAL CHAIN HYDROCARBON PYROLYSIS REACTIONS

N.A. Vasilieva, N.F. Uvarov* (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia)

Kinet. Catal., 52(1) (2011) pp. 98-103.

The electrical conductivity of polycrystalline MgO between 350 and 750°C is determined by the transport of surface electronic and hole defects and depends on the applied voltage. Near 620°C at low applied voltages, the conductivity decreases by 1–2 orders of magnitude in a narrow temperature range (ΔT = 75°C), and this is accompanied by a change of the sign of the surface charge carriers. The “ignition” of the catalytic activity of magnesium oxide in free radical generation in radical chain hydrocarbon pyrolysis is observed in the same temperature range. It is assumed that the change of the sign of the charge carriers is due to the existence of an isoelectric temperature Ti and that, at T > Ti, OO· defects come out to the magnesium oxide surface.

AMMONIA SYNTHESIS FROM DINITROGEN AND DIHYDROGEN OVER THE CATALYSTS BASED ON SUPPORTED MONONUCLEAR POTASSIUM CARBONYL RUTHENATE. PROMOTING EFFECT OF ALKYLLITHIUM COMPOUNDS

S.M. Yunusov*, E.S. Kalyuzhnaya*, B.L. Moroz, A.S. Ivanova, V.B. Shur* (*Nesmeyanov Institute of Organoelement Compounds, Moscow, Russia)

Russ. Chem. Bull., 60(9) (2011) pp. 1842-1847.

New catalysts for the ammonia synthesis from dinitrogen and dihydrogen based on supported mononuclear potassium carbonyl ruthenate K2Ru[(CO)4] as a precursor of catalytically active particles have been developed. Magnesium oxide and graphite-like active carbon Sibunit were used as supports, while aliphatic organolithium compounds (BunLi and ButLi) were employed as electron promoters in these catalysts. The systems with MgO as a support are the most efficient. The introduction of RLi into these systems allows one to considerably increase the ammonia synthesis rate. When using carbon Sibunit, the promoting effect of organolithium compounds is much weaker but the activity of such catalysts can be essentially increased by the introduction of an additional electron promoter, viz., metallic potassium, into the system. All the catalysts tested are active in the ammonia synthesis at atmospheric pressure and temperatures ≥250°C.

Application of Physicochemical Methods for Characterization of Catalysts,
Supports, Synthesized Substances and Matertials

X-RAY DIFFRACTION STRUCTURE DIAGNOSTICS OF NANOMATERIALS

E.M. Moroz

Russ. Chem. Rev., 80(4) (2011) pp. 293-312.

The review concerns the development and applications of the X-ray diffraction method of the radial electron density distribution based on the integral analysis of X-ray diffraction in studies of nanomaterials, in particular, oxide supports for catalysts. The method provides information on the interatomic distances and coordination numbers in the structure and allows one to detect and estimate the size of nanostructures (phases) less than 3 nm in size, which cannot be detected by conventional powder X-ray diffraction analysis. The method is sensitive to the changes in the local structure measuring 1-3 unit cells; therefore, it is successfully used to identify various defects in nanoobjects of any chemical composition. The bibliography includes 124 references.

STUDY OF PHASE COMPOSITION OF NANOMATERIALS

E.M. Moroz

Nanoeng., 5 (2011) pp. 26-32.

The possibilities of X-ray techniques to determine the phase composition of typical nanomaterials and nanostructures - catalysts and carriers for them – are considered. For supported catalysts it is shown that besides phases characteristic for support and active component, there are always present the phase formed as a result of interaction between support and active component. Metastable phases are identified for oxide systems. Examples of investigation of defective nanostructures are considered.

POSSIBILITIES OF X-RAY DIFFRACTION STRUCTURE DIAGNOSTICS OF NANOMATERIALS

E.M. Moroz

Nanoeng., 4 (2011) pp. 3-21.

In this work the data on the development and use of radial electron distribution function or pair distribution function method based on integral analysis of X-ray scattering curve are presented. The method gives information about interatomic distances and coordination numbers and it is used for detection of nanospecies (phases) with sizes lower than 3 nm and estimation of their sizes. Such highly dispersed species are not detected by conventional X-ray phase analysis based on consideration of interplanar spacings. The method is sensitive to changes in local structure (short range arrangement of atoms in the range of 1...3 elementary cells), so it is used successfully for determination of defects in the nanomaterials.

A STUDY OF THE LOCAL STRUCTURE OF ALUMINAS OBTAINED BY DIFFERENT METHODS

E.M. Moroz, K.I. Shefer, D.A. Zyuzin, A.N. Shmakov

J. Struct. Chem., 52(2) (2011) pp. 326-329.

The local structure of aluminas obtained from hydroxides (pseudo-boehmites) synthesized by different methods is studied using the radial density distribution function. The occupancy of the cation sites of different types (tetrahedral and octahedral, spinel and non-spinel) in the structure of the studied oxides is analyzed.

Pt-IMPLANTED INTERMETALLIDES AS THE CATALYSTS FOR CH4-CO2 REFORMING

L.A. Arkatova*, O.V. Pakhnutov*, A.N. Shmakov, Yu.S. Naiborodenko**, N.G. Kasatsky*** (*Tomsk V.V. Kuibyshev State University, Tomsk, Russia; **Tomsk Scientific Center, Tomsk, Russia)

Catal. Today, 171(1) (2011) pp. 156-167.

A new type of catalytic system on the base of Ni3Al intermetallic compound was proposed for CO2 reforming of methane. Several catalysts were prepared by self-propagating high temperature synthesis and characterized by XRD (in situ and ex situ), DTA-TG, SEM + EDS, HRTEM + EDS and XPS. Ion implantation was used as a method of catalyst surface modification. Activity testing has been performed in the fixed bed reactor at the temperatures of 600–900°C under atmospheric pressure and the reactant molar ratio of 1. The structure and morphology of different types of carbon deposits obtained on the surface of unmodified Ni3Al were investigated. The results indicated that the addition of a low amount (less than 0.1 wt%) of Pt to the Ni3Al intermetallide leads to a decrease in carbon deposition and Pt-implanted catalysts were stable for a long period of time. The evidence suggests that the differences in the stabilities may be due to the following reasons: (1) Pt prevents Ni phase sintering by avoiding particle coalescence, which is the main sintering process under severe CH4–CO2 reforming conditions, (2) Pt hinders deactivating carbon formation by limiting bulk nickel carbide and therefore carbon filament formation, which may lead to reactor plugging and/or particle fragmentation, and by suppressing encapsulating carbon formation which limits access of reactant to the active nickel phase.

ACTIVITY OF COPPER–CERIUM–ZIRCONIUM CATALYSTS IN OXIDATION OF HYDROGEN

A.V. Gural’skii*, G.R. Kosmambetova*, E.M. Moroz, V.I. Gritsenko*, P.E. Strizhak*

(*Pisarzhevskii Institute of Physical Chemistry, Kiev, Ukraine)

Theor. Exp. Chem., 47(4) (2011) pp. 251-256.

The authors have studied the catalytic properties in oxidation of hydrogen for copper–cerium oxide systems deposited on supports obtained by calcination of yttrium-stabilized zirconium dioxide at 300–100°C. The authors have shown that the catalytic activity of the samples obtained depends on the specific surface area of the original supports and the amount of reduced copper within the composition of the catalyst. In samples whose support has high specific surface area, the content of reduced metallic copper is greater and the catalytic activity is higher.

LOW TEMPERATURE HYDROGEN PURIFICATION FROM CO FOR FUEL CELL APPLICATION OVER COPPER-CERIA CATALYSTS SUPPORTED ON DIFFERENT OXIDES

G.R. Kosmambetova*, E.M. Moroz, A.V. Guralsky*, V.P. Pakharukova, A.I. Boronin, T.S. Ivashchenko*, V.I. Gritsenko*, P.E. Strizhak* (*Pisarzhevskii Institute of Physical

Chemistry, Kiev, Ukraine)

Int. J. Hydrogen Energy, 36(1) (2011) pp. 1271-1275.

The CuO–CeO2–MeOx (Me = Zr, Ti, Mn, Al; x = 1.5–2) solids were tested in the preferential CO oxidation reaction in hydrogen-rich gas mixtures (PROX). The authors study an effect of a support (MeOx) on the CO conversion and selectivity in the PROX reaction showing that monoclinic zirconia (m-zirconia) with low surface area is the most effective support. The optimal catalyst composition was determined by varying copper and ceria loadings over m-zirconia. XRD and XPS studies indicate that a good catalytic performance of m-zirconia supported copper–ceria catalysts may be attributed to the presence of dispersed Cu-containing species that interact with CeO2 and ZrO2.

 

EFFECTS OF SPATIAL ORDERING OF QUANTUM DOT ARRAYS FROM SMALL-ANGLE X-RAY DIFFRACTION DATA UNDER VARIATION OF GROWTH PARAMETERS

L.M. Plyasova, LYu. Molina, N.P. Stepina*, A.F. Zinov’eva*, A.V. Dvurechenskii* (*Institute of Semiconductor Physics, Novosibirsk, Russia)

J. Surf. Invest. - X-Ray Synchrotron Neutron Techn., 5(1) (2011) pp. 120-125.

The small angle X-ray diffraction method is applied to the system of germanium quantum dots in the silicon matrix prepared by molecular-beam epitaxy in self-organization mode using the Stranski-Krastanov technique. Depending on the growth mode, the specific distances between Ge quantum dots and deviations from their correlated distribution are determined. The results are in agreement with the scanning tunneling microscopy data.

ELECTRODEPOSITED OXOTUNGSTATE FILMS: TOWARDS THE MOLECULAR NATURE OF RECHARGING PROCESSES

V.K. Laurinavichute*, S.Yu. Vassiliev*, A.A. Khokhlov*, L.M. Plyasova, LYu. Molina, G.A. Tsirlina* (*Moscow Lomonosov State University, Moscow, Russia)

Electrochim. Acta, 56(10) (2011) pp. 3530-3536.

In situ Raman spectroscopy is applied to supplement voltammetric, spectroelectrochemical, and XRD data on redox transformations of electrodeposited oxotungstate films. These films undergo electrochromic transition at rather positive potentials, as compared to usual sputtered tungsten oxides. The depth of electroreduction for the films conditioned in acidic solutions under open circuit is about 0.11 e" per W atom. Coloration of the films correlates with the decrease of Raman band, corresponding to the terminal W(VI)=O vibration in the hydrated phase of highly defective tungstic acid (hydrated tungsten oxide). The data allow to state the absence of oxotungstate octahedra rearrangement in the course of reduction at positive RHE potentials, and to assume that slightly deeper reduction up to 0.15 W(V)/[W(V) + W(VI)] ratio is possible at more negative potentials. The authors also demonstrate that the gas phase reduction is less reversible as compared to electrochemical reduction in solution. The most possible nature of films degradation in the gas phase is their partial dehydration in the course of reduction.

HIGH-TEMPERATURE XRD INVESTIGATION OF SPINEL Mn1.5Al1.5O4 DECOMPOSITION

O.A. Bulavchenko, S.V. Tsybulya, E.Yu. Gerasimov, S.V. Cherepanova, T.N. Afonasenko*, P.G. Tsyrulnikov* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Z. Kristallogr. Proc., 1 (2011) pp. 325-330.

This article describes a study of behaviour of cubic Mn1.5Al1.5O4 spinel during heating and cooling under air. High-temperature XRD and TEM were used to investigate structure transformations and sample microstructure. XRD data show spinel decomposition during cooling and heating under air at 500-700°C. The products of decomposition consist of nanocrystalline tetragonal phase (with particle size of 20 nm) and cubic spinel (50 nm). Cubic spinel composition changes by various ways on the initial step during the heating and cooling. Thus, the structure mechanisms of decomposition are different. But the final decomposition products are the same.

PRODUCING OF Cu/ZrO2 COMPOSITES BY COMBINING MECHANICAL ACTIVATION AND SELF-PROPAGATING HIGH-TEMPERATURE SYNTHESIS

T.F. Grigor’eva*, A.I. Letsko**, T.L. Talako**, S.V. Tsybulya, I.A. Vorsina*, A.P. Barinova*, A.F. Il’yushchenko**, N.Z. Lyakhov* (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **Institute of Powder Metallurgy NAS Belarus)

Combust. Explosion Shock Waves, 47(2) (2011) pp. 174-178.

The possibility of producing Cu/ZrO2 composites by combining mechanical activation and self-propagating high-temperature synthesis (SHS) is studied using X-ray diffraction and electron microscopy. It is shown that Cu/ZrO2 composites are formed in SHS using CuO/Cu/Zr mechanocomposite as a precursor.

INFLUENCE OF Al IONS ON THE REDUCTION OF Co3xAlx04: in situ XRD INVESTIGATION

S.V. Cherepanova, O.A. Bulavchenko, I.I. Simentsova, E.Yu. Gerasimov, A.A. Khassin

Z. Kristallogr. Proc, 1 (2011) pp. 331-336.

The addition of small amounts of Al ions to nanocrystalline Co3O4 leads to considerable changes in its reduction. In situ XRD and TPR show that Al ions affect the extent of cobalt reduction achieved in a hydrogen flow. Co3O4 is fully reduced to metallic cobalt at a temperature of ca. 200°C. As for Al-modified samples Co3-xAlxO4 (x = 0.05, 0.1, 0.2), they contain CoO even after reduction at 350°C. The higher is the Al content; the lower is the Co/CoO ratio. At 350°C, metallic particles in all cases consist of platelet domains having the hcp and fcc structure. In the case of metallic cobalt reduced from Co3O4, the fcc domains are twice thinner as compared to hcp ones, their average thicknesses being ca. 0.9 nm and 1.8 nm, respectively. In metallic cobalt reduced from Co3-xAl x O4 (x = 0.05, 0.1, 0.2), the fcc and hcp domains have almost equal average thicknesses of ca. 1.4 nm.

ANIONIC COMPOSITION OF PRECURSORS OF THE Co/Al203 CATALYSTS FOR THE FISCHER-TROPSCH SYNTHESIS

LI. Simentsova, A.A. Khassin, G.A. Filonenko, G.K. Chermashentseva, O.A. Bulavchenko, S.V. Cherepanova, T.M. Yurieva

Russ. Chem. Bull., 60(9) (2011) pp. 1827-1834.

Cobalt and aluminum hydroxo compounds with the hydrotalcite-type structure containing nitrate, carbonate, and hydroxyl groups are formed due to the deposition by precipitation of cobalt cations from a nitrate solution on 5- and y-Al2O3 under the conditions of urea hydrolysis. The influence of the method of preparation on the anionic composition of the hydroxo compounds (precursors of the Co-Al catalyst) was studied. A correlation between the anionic composition of the precursor compound and the catalytic properties of the catalysts in the Fischer-Tropsch synthesis was established.

SYNTHESIS, CRYSTAL STRUCTURE AND THERMAL PROPERTIES OF [Co(NH3)5Cl]MoO4(M = Mo, W)

E.A. Shusharina*, S.P. Khranenko*, P.E. Plusnin*, T.Yu. Kardash, S.A. Gromilov*

(*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Struct. Chem., 52(5) (2011) pp. 918-923.

Crystal structures of [Co(NH3)5Cl]MoO4 and [Co(NH3)5Cl]WO4 complex salts are determined by single crystal X-ray diffraction. It is demonstrated for both salts that within the temperature range T = -123-20°C there is a negative thermal expansion (about 0.26%) towards the с axis of the orthorhombic unit cell (Pnma space group). Thermal properties of the salts are investigated. The phase composition of the products obtained on heating the salts in different gas atmospheres is studied.

CRYSTAL STRUCTURE AND THERMAL PROPERTIES OF [AuCen^hlCu^O^bSHjO

E.V. Makotchenko*, E.A. Bykova*, E.Yu. Semitut*, Yu.V. Shubin*, P.V. Snytnikov, P.E. Plyusnin* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Struct. Chem., 52(5) (2011) pp. 924-929.

The crystal structure of a double complex salt of the composition [Au(en)2]2[Cu(C2O4)2]3-8H2O (en = ethylenediamine) at 150 K is determined by single crystal X-ray diffraction. The crystal data for C20H48Au2Cu3N8O32 are: a = 9.1761(3) Å, b = 16.9749(6) Å, c = 13.4475(5) Å, (3 = 104.333(1)°, V = 2029.43(12) Å3, P21/c space group, Z = 2, dx = 2.450 g/cm3. It is demonstrated that the thermal decomposition of the double complex salt in a helium or hydrogen atmosphere affords the solid solution Au0.4Cu0.6.

 

MICROPOROUS SENSOR: GAS SORPTION, GUEST EXCHANGE AND GUEST-DEPENDANT LUMINESCENCE OF METAL-ORGANIC FRAMEWORK

S.A. Sapchenko*, D.G. Samsonenko*, D.N. Dybtsev*,**, M.S. Melgunov, V.P. Fedin* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Division of the Advanced Materials Science, POSTECH, Hyojadong, Pohang, Republic of Korea)

Dalton Trans., 40(10) (2011) pp. 2196-2203.

Zn(II)-containing metal–organic framework (MOF) [Zn4(dmf)(ur)2(ndc)4] (ndc2- = 2,6-naphtalenedicarboxylate, ur = urotropin, dmf = N,N′-dimethylformamide) was synthesized and characterized by X-ray crystallography and gas sorption analysis. Host MOF retains its crystallinity after guest removal and exchange. Single-crystal to single-crystal formation of different host–guest systems with benzene and ferrocene was investigated. Interesting guest-depended luminescence properties of the porous host framework were observed.

XPS FOR in situ STUDY OF THE MECHANISMS OF HETEROGENEOUS CATALYTIC REACTIONS

V.V. Kaichev, I.P. Prosvirin, V.I. Bukhtiyarov

J. Struct. Chem., 52(suppl.) (2011) pp. 90-101.

The possibility to use X-ray photoelectron spectroscopy (XPS) for in situ studies of the mechanisms of heterogeneous catalytic reactions over the pressure range from ultrahigh vacuum to 100 mbar is considered. The application of this method to investigation of CO adsorption and hydrogenation as well as kinetics and mechanism of methanol transformation on the palladium surface at pressures of 10-6 mbar to 0.1 mbar is reported.

A STUDY OF THE STRUCTURE OF (HfO2)x(Al2O3)1-x/Si FILMS BY X-RAY PHOTOELECTRON SPECTROSCOPY

V.V. Kaichev, Yu.V. Dubinin, T.P. Smirnova*, M.S. Lebedev* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Struct. Chem., 52(3) (2011) pp. 480-487.

By X-ray photoelectron spectroscopy (XPS), using the technique of layer-by-layer analysis, the films of (HfO2)x(Al2O3)1-x solid solutions synthesized by chemical vapor deposition are studied. The possibility to determine the structure of solid binary solutions based on the analysis of the XPS spectra is demonstrated.

X-RAY PHOTOELECTRON SPECTROSCOPY DEPTH PROFILING OF La2O3/Si THIN FILMS DEPOSITED BY REACTIVE MAGNETRON SPUTTERING

C.V. Ramana*, R.S. Vemuri*, V.V. Kaichev, V.A. Kochubey**, A.A. Saraev, V.V. Atuchin**

(*University of Texas at El Paso, El Paso, Texas, USA; **Institute of Semiconductor Physics, Novosibirsk, Russia)

ACS Appl. Mater. Interfaces, 3(11) (2011) pp. 4370-4373.

The La2O3/Si thin films have been deposited by reactive DC magnetron sputtering. Amorphous state of La2O3 layer has been shown by RHEED observation. Top surface chemistry of the a-La2O3 has been evaluated with layer-by-layer depth profiling by ion bombardment and XPS measurements. It was found by core level spectroscopy that the top surface of the a-La2O3 film consists of hydrocarbon admixture, lanthanum carbonate, and hydroxides that formed as a result of contact with air atmosphere. Thickness of this top surface modified layer is below 1 nm for a contact time of ~ 1.5 h with air at normal conditions.

ELECTRONIC STRUCTURE OF δ-Ta2O5 WITH OXYGEN VACANCY:I>ab initio CALCULATIONS AND COMPARISON WITH EXPERIMENT

M.V. Ivanov*, T.V. Perevalov*, V.S. Aliev*, V.A. Gritsenko*, V.V. Kaichev (*Rzhanov Institute of Semiconductor Physics, Novosibirsk, Russia)

J. Appl. Phys., 110(2) (2011) pp. 024115 (5 pp).

Electronic structure of oxygen vacancies in Ta2O5 have been studied theoretically by first-principles calculations and experimentally by X-ray photoelectron spectroscopy. Calculations of δ-Ta2O5 were performed using density functional theory within gradient-corrected approximation with the +U approach. Results indicate that the oxygen vacancy causes a defect level in the energy gap at 1.2 eV above the top of the valence band. To produce oxygen vacancies, amorphous films of Ta2O5 were bombarded with Ar+ ions. XPS results indicate that the Ar-ion bombardment leads to the generation of the oxygen vacancies in Ta2O5 that characterize the peak at 2 eV above the valence band. The calculated spectrum of crystalline δ-Ta2O5 demonstrates qualitative correspondence with the XPS spectrum of the amorphous Ta2O5 film after Ar-ion bombardment.

Ab initio SIMULATION OF THE ELECTRONIC STRUCTURE OF δ-Ta2O5 WITH OXYGEN VACANCY AND COMPARISON WITH EXPERIMENT

M.V. Ivanov*, T.V. Perevalov*, V.Sh. Aliev*, V.A. Gritsenko*, V.V. Kaichev (*Rzhanov Institute of Semiconductor Physics, Novosibirsk, Russia)

J. Exp. Theor. Phys., 112(6) (2011) pp. 1035-1041.

The electronic structure of a Ta2O5 insulator with oxygen vacancies is studied theoretically and experimentally. The ab initio calculations of δ-Ta2O5 are performed in terms of density functional theory using the generalized gradient (GGA) and GGA + U approximations. The electronic structure of Ta2O5 is experimentally studied by X-ray photoelectron spectroscopy (XPS). To study oxygen vacancies, an amorphous Ta2O5 film is irradiated by argon ions. The calculated XPS spectra of the valence band of δ-Ta2O5 agree satisfactorily with the corresponding experimental spectra of the amorphous films. The oxygen vacancy in δ-Ta2O5 is found to be a trap for holes and electrons. The minimum and maximum effective masses of electrons and holes in δ-Ta2O5 are calculated.

NEW TECHNIQUE FOR HETEROGENEOUS VAPOR-PHASE SYNTHESIS OF NANOSTRUCTURED METAL LAYERS FROM LOW-DIMENSIONAL VOLATILE METAL COMPLEXES

A.M. Badalyan*, L.F. Bakhturova*, V.V. Kaichev, O.V. Polyakov*, O.P. Pchelyakov**, G.I. Smirnov** (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Institute of Semiconductor Physics, Novosibirsk, Russia)

Tech. Phys., 56(9) (2011) pp. 1333-1338.

A new technique for depositing thin nanostructured layers on semiconductor and insulating substrates that is based on heterogeneous gas-phase synthesis from low-dimensional volatile metal complexes is suggested and tried out. Thin nanostructured copper layers are deposited on silicon and quartz substrates from low-dimensional formate complexes using a combined synthesis-mass transport process. It is found that copper in layers thus deposited is largely in a metal state (Cu0) and has the form of closely packed nanograins with a characteristic structure.

FROM ‘CORE–SHELL’ TO COMPOSITE MIXED CATHODE MATERIALS FOR RECHARGEABLE LITHIUM BATTERIES BY MECHANOCHEMICAL PROCESS

N.V. Kosova*, E.T. Devyatkina*, V.V. Kaichev, A.B. Slobodyuk** (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **Institute of Chemistry, Vladivostok, Russia)

Solid State Ionics, 192(1) (2011) pp. 284-288.

Solid state mechanical activation method was applied for surface modification of LiMn2O4 by Li–M–O (M = Co, Co+Ni) and for preparation of composite mixed LiMn2O4/LiCoO2 cathode materials. Pristine LiMn2O4 was ground with correspondent precursors (for coating) or with LiCoO2 (for composites) in high-energy planetary mills and then heat treated at different temperatures. As prepared materials were studied by XRD, 7Li MAS NMR spectroscopy, XPS, SEM and electrochemical cycling. It has been shown that both ‘core–shell’ and composite materials prepared by mechanochemical process are characterized by superior electrochemical performance due to smaller particles and chemical modification of LiMn2O4.

XPS STUDY OF PHARMACOLOGICAL SUBSTANCES MECHANOCHEMICALLY IMMOBILIZED ON THE SURFACE OF ALUMINA

A.I. Nizovskii, A.V. Kalinkin, T.P. Shakhtshneider*, M.A. Dyakonova*, S.A. Myz*, E.V. Boldyreva*, R. Kumar** (*Institute of Solid-State Chemistry and Mechanochemistry, Novosibirsk, Russia; **National Metallurgical Laboratory, Jamshedpur, Bihar, India)

J. Struct. Chem., 52(suppl.) (2011) pp. 137-144.

Piroxicam and meloxicam nanocomposites with alumina were synthesized by mechanochemical treatment of medicinal substances mixed with the oxide. X-ray photoelectron spectroscopy demonstrated that interaction of the components during mechanicalactivation proceeds via binding the amide and sulfate groups in the molecules of medicinal substances with the active sites of alumina surface. XPS studies confirmed the formation of “core-shell” composites with the shell represented by medicinal substances distributed over the support surface.

MECHANOCHEMICAL PREPARATION OF ORGANIC-INORGANIC HYBRID MATERIALS OF DRUGS WITH INORGANIC OXIDES

T.P. Shakhtshneider*, S.A. Myz*, M.A. Dyakonova*, V.V. Boldyrev*, E.V. Boldyreva*, A.I. Nizovskii, A.V. Kalinkin, R. Kumar** (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **National

Metallurgical Laboratory, Jamshedpur, Bihar, India)

Acta Phys. Pol., A, 120(2) (2011) pp. 272-278.

The nanocomposites of piroxicam and meloxicam with alumina were obtained by ball-milling as a result of distribution of the drugs at the surface of oxide with formation of the stable composites. The observed changes in the IR spectra of the ball-milled mixtures suggested the interaction of the drugs with the alumina active surface sites. The functional groups in molecules of piroxicam and meloxicam involved into formation of bonds between the drugs and the surface of the oxide were determined, they are amide, sulfate, enol groups, and pyridyl/thiazolyl nitrogen atoms. It appears that the formation of the new bonds at the contacts of particles in the composite leads to the stabilization of the drugs in metastable state inhibiting their transformation into initial crystalline form.

USE OF THE DIFFERENTIAL CHARGING EFFECT IN XPS TO DETERMINE THE NATURE OF SURFACE COMPOUNDS RESULTING FROM THE INTERACTION OF A Pt/(BaCO3 + CeO2) MODEL CATALYST WITH SOx

M.Yu. Smirnov, A.V. Kalinkin, A.A. Dubkov*, E.I. Vovk, A.M. Sorokin, A.I. Nizovskii, B. Carberry*, V.I. Bukhtiyarov (*Ford Forschungszentrum, Aachen, Germany)

Kinet. Catal., 52(4) (2011) pp. 595-604.

Changes in the chemical composition of the surface of a Pt/(BaCO3 + CeO2) model NOx storage-reduction catalyst upon its interaction with SOx (SO2 (260 Pa) + O2 (2600 Pa) + H2O (525 Pa)) followed by regeneration in a mixture of CO (2100 Pa) with H2O (525 Pa) were studied by X-ray photoelectron spectroscopy (XPS). Model catalyst samples were prepared as a thin film (about several hundreds of angstrom units in thickness) on the surface of tantalum foil coated with a layer of aluminum oxide (∼100 Å). It was found that the Pt/BaCO3 and Pt/CeO2 catalyst constituents acquired different surface charges (differential charging) in the course of photoelectron emission; because of this, it was possible to determine the nature of surface compounds formed as a result of the interaction of the catalyst with a reaction atmosphere. It was found that barium carbonate was converted into barium sulfate as a result of reaction with SOx on the surface of BaCO3 at 150°C. As the treatment temperature in SOx was increased to 300°C, the formation of sulfate on the surface of CeO2 was observed. The sulfatization of CeO2 was accompanied by the reduction of Ce(IV) to Ce(III). The regeneration reaction of the catalyst treated in SOx at 300°C resulted in the consecutive decomposition of cerium(III) sulfate at ≤500°C and then barium sulfate at 600–700°C. Upon the decomposition of BaSO4, a portion of sulfur was converted into a sulfide state, probably, because of the formation of BaS.

SPECTROSCOPIC ELLIPSOMETRY AND X-RAY PHOTOELECTRON SPECTROSCOPY OF La2O3 THIN FILMS DEPOSITED BY REACTIVE MAGNETRON SPUTTERING

V.V. Atuchin*, A.V. Kalinkin, V.A. Kochubey*, V.N. Kruchinin*, R.S. Vemuri**, C.V. Ramana** (*Institute of Semiconductor Physics, Novosibirsk, Russia; **University of Texas at El Paso, El Paso, Texas, USA)

J. Vac. Sci. Technol., A, 29(2) (2011) 021004 (5 pp.).

Lanthanum oxide (La2O3) films were grown by the reactive dc magnetron sputtering and studied their structural, chemical and optical parameters. La2O3 films were deposited onto Si substrates by sputtering La-metal in a reactive gas (Ar+O2) mixture at a substrate temperature of 200°C. Reflection high-energy electron diffraction measurements confirm the amorphous state of La2O3 films. Chemical analysis of the top-surface layers evaluated with X-ray photoelectron spectroscopy indicates the presence of a layer modified by hydroxylation due to interaction with atmosphere. Optical parameters of α-La2O3 were determined with spectroscopic ellipsometry (SE). There is no optical absorption over spectral range λ = 250–1100 nm. Dispersion of refractive index of α-La2O3 was defined by fitting of SE parameters over λ = 250–1100 nm.

A DIRECT EVIDENCE FOR THE INSTABILITY AND DEACTIVATION OF MIXED-OXIDE SYSTEMS: INFLUENCE OF SURFACE SEGREGATION AND SUBSURFACE DIFFUSION

E. Emmez*, E.I. Vovk, V.I. Bukhtiyarov, E. Ozensoy* (*Bilkent University, Bilkent, Ankara,Turkey)

J. Phys. Chem. C, 115(45) (2011) pp. 22438-22443.

In the current contribution, a direct demonstration is provided of the thermally induced surface structural transformations of an alkaline-earth oxide/transition metal oxide interface that is detrimental to the essential catalytic functionality of such mixed-oxide systems toward particular reactants. The BaOx/TiO2/Pt(111) surface was chosen as a model interfacial system where the enrichment of the surface elemental composition with Ti atoms and the facile diffusion of Ba atoms into the underlying TiO2 matrix within 523–873 K leads to the formation of perovskite type surface species (BaTiO3/Ba2TiO4/BaxTiyOz). At elevated temperatures (T > 973 K), excessive surface segregation of Ti atoms results in an exclusively TiO2/TiOx-terminated surface which is almost free of Ba species. Although the freshly prepared BaOx/TiO2/Pt(111) surface can strongly adsorb ubiquitous catalytic adsorbates such as NO2 and CO2, a thermally deactivated surface at T > 973 K practically loses all of its NO2/CO2 adsorption capacity due to the deficiency of surface BaOx domains.

ROLE OF THE EXPOSED Pt ACTIVE SITES AND BaO2 FORMATION IN NOx STORAGE REDUCTION SYSTEMS: A MODEL CATALYST STUDY ON BaOx/Pt(111)

E.I. Vovk, E. Emmez*, M. Erbudak**, V.I. Bukhtiyarov, E. Ozensoy* (*Bilkent University, Bilkent, Ankara, Turkey; **Laboratorium für Festkörperphysik, ETH Zurich, Zurich, Switzerland)

J. Phys. Chem. C, 115(49) (2011) pp. 24256-24266.

BaOx (0.5 MLE - 10 MLE)/Pt(111) (MLE: monolayer equivalent) surfaces were synthesized as model NOx storage reduction (NSR) catalysts. Chemical structure, surface morphology, and the nature of the adsorbed species on BaOx/Pt(111) surfaces were studied via X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED). For θBaOx < 1 MLE, (2 × 2) or (1 × 2) ordered overlayer structures were observed on Pt(111), whereas BaO(110) surface termination was detected for θBaOx = 1.5 MLE. Thicker films (θBaOx ≥ 2.5 MLE) were found to be amorphous. Extensive NO2 adsorption on BaOx(10 MLE)/Pt(111) yields predominantly nitrate species that decompose at higher temperatures through the formation of nitrites. Nitrate decomposition occurs on BaOx(10 MLE)/Pt(111) in two successive steps: NO(g) evolution and BaO2 formation at 650 K and NO(g) + O2(g) evolution at 700 K. O2(g) treatment of the BaOx(10 MLE)/Pt(111) surface at 873 K facilitates the BaO2 formation and results in the agglomeration of BaOx domains leading to the generation of exposed Pt(111) surface sites. BaO2 formed on BaOx(10 MLE)/Pt(111) is stable even after annealing at 1073 K, whereas on thinner films (θBaOx = 2.5 MLE), BaO2 partially decomposes into BaO, indicating that small BaO2 clusters in close proximity of the exposed Pt(111) sites are prone to decomposition. Nitrate decomposition temperature decreases monotonically from 550 to 375 K with decreasing BaOx coverage within θBaOx = 0.5 to 1.0 MLE. Nitrate decomposition occurs at a rather constant temperature range of 650-700 K for thicker BaOx overlayers (2.5 MLE < θBaOx < 10 MLE). These two distinctly characteristic BaOx-coverage-dependent nitrate decomposition regimes are in very good agreement with the observation of the so-called “surface” and “bulk” barium nitrates previously reported for realistic NSR catalysts, clearly demonstrating the strong dependence of the nitrate thermal stability on the NOx storage domain size.

X-RAY PHOTOELECTRON INVESTIGATION OF CHARGE DISTRIBUTION IN COPPER(II) PHTHALOCYANINE COMPLEXES

R.V. Gulyaev, N.A. Kryuchkova*, L.N. Mazalov*, A.I. Boronin, T.V. Basova*, V.A. Plyashkevich*

(*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Surf. Invest. -

X-Ray Synchrotron Neutron Techn.,

5(1) (2011) pp. 48-56.

The charged states of atoms in unsubstituted copper(II) phthalocyanine (CuPcH16) and hexade-cafluorinated copper(II) phthalocyanine (CuPcF16) complexes and in thin films of them deposited on silicon substrates by vacuum thermal evaporation are investigated by X-ray photoelectron spectroscopy (XPS). The C(1s), N(1s), Cu(2p) core level energies and the charged states of atoms in the studied complexes are calculated using the DFT method. The performed experimental study and theoretical

calculations show that the introduction of electron acceptor substituents into benzene rings mostly affects the atoms of benzene rings and insignificantly affects the charge state of nitrogen atoms in the pyrrole ring.

MICELLAR SYNTHESIS AND CHARACTERIZATION OF ULTRAFINE SILVER POWDERS

M.G. Demidova*, A.I. Bulavchenko*, T.Yu. Podlipskaya*, A.I. Boronin, L.S. Kibis, V.I. Zaikovsky (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Russ. J. Inorg. Chem., 56(8) (2011) pp. 1199-1207.

Methods for the synthesis and coagulation of ultrafine silver powders in the water-Triton N-42-decane inverted-micellar system were developed. Varying AgNO3 concentration (1–5 mol/L), the type of reducing agent (hydrazine or potassium borohydride), and the coagulation method (spontaneous or induced by acetone or water addition) allowed to select the parameters that provide powders containing about 98% silver and having particle sizes of 15–80 nm. The authors propose methodology for characterizing ultrafine silver powders comprising the determination of the total and surface composition and the charge state of impurities using atomic absorption spectroscopy (AAS), atomic emission spectroscopy (AES), microanalysis, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The impurity composition of the nanomaterial is found to depend on the type of reducing agent, the synthesis parameters, and coagulation conditions.

XES AND QUANTUM CHEMICAL INVESTIGATION OF THE ELECTRONIC STRUCTURE OF PHTHALOCYANINE COMPLEXES MPCH16 AND MPCF16 WITH M = Cu, Co

G.I. Semushkina*, L.N. Mazalov*, N.A. Kryuchkova*, A.I. Boronin, R.V. Gulyaev, T.V. Basova*, V.A. Plyashkevich* (*Nikolaev Institute of Inorganic Chmestry, Novosibirsk, Russia)

J. Struct. Chem., 52(suppl.) (2011) pp. 21-35.

The X-ray spectroscopy and X-ray electron study of the electronic structure of unsubstituted phthalocyanines MPcH16 and hexadecafluorophthalocyanines MPcF16 with M = Cu, Co is reported. Quantum-chemicalalculation of the electronic structure of these compounds was performed. The calculation was used to analyze the metal-ligand electronic interaction in the complexes. The theoretically calculated energy position and composition of the highest occupied molecular orbitals were compared with experimental data obtained from X-ray fluorescence spectra.

MOBILITY OF SOLID TERT-BUTYL ALCOHOL STUDIED BY DEUTERIUM NMR

A.M. Nishchenko, D.I. Kolokolov, A.G. Stepanov

J. Phys. Chem. A, 115(26) (2011) pp. 7428-7436.

The molecular mobility of solid deuterated tert-butyl alcohol (TBA) has been studied over a broad temperature range (103-283 K) by means of solid-state 2H NMR spectroscopy, including both line shape and anisotropy of spin—lattice relaxation analyses. It has been found that, while the hydroxyl group of the TBA molecule is immobile on the 2H NMR time scale (τC > 10―5 s), its butyl group is highly mobile. The mobility is represented by the rotation of the methyl [CD3] groups about their 3-fold axes (C3 rotational axis) and the rotation of the entire butyl [(CD3)3-C] fragment about its 3-fold axis (C3' rotational axis). Numerical simulations of spectra line shapes reveal that the methyl groups and the butyl fragment exhibit three-site jump rotations about their symmetry axes C3 and C3' in the temperature range of 103-133 K, with the activation energies and preexponential factors E1 = 21 ± 2 kJ/mol, f01 = (2.6 ± 0.5) x 1012 s―1 and E2 = 16 ± 2 kJ/mol, k02 = (1 ± 0.2) x 1012 s―1, respectively. Analysis of the anisotropy of spin―lattice relaxation has demonstrated that the reorientation mechanism of the butyl fragment changes to a free diffusion rotational mechanism above 173 K, while the rotational mechanism of the methyl groups remains the same. The values of the activation barriers for both rotations at T > 173 K have the values, which are similar to those at 103―133 K. This indicates that the interaction potential defining these motions remains unchanged. The obtained data demonstrate that the detailed analysis of both line shape and anisotropy of spin-lattice relaxation represents a powerful tool to follow the evolution of the molecular reorientation mechanisms in organic solids.

QUADRUPOLAR METAL NMR OF OXIDE MATERIALS INCLUDING CATALYSTS

O.B. Lapina, V.V. Terskikh

Encyclopedia of Magnetic Resonance, Eds. R.K Harris, R.E Wasylishen, John Wiley & Sons, Ltd, 2011.

In this work, the authors review the basic methodology and recent applications of quadrupolar metal solid-state NMR spectroscopy in oxide systems with emphasis on materials science and catalysis. Three typical quadrupolar metal nuclei, 51V, 93Nb, and 95Mo, are discussed in detail to illustrate the complex interplay between the quadrupolar and chemical shielding interactions in oxides. In the first part, a systematic overview is given of the metal coordination environments in oxides and their corresponding NMR parameters. The importance of quantum chemical calculations in correlating experimental NMR results with a molecular level oxide structure is highlighted. In the second part, examples of quadrupolar metal NMR in materials science are presented, including paramagnetic oxide systems, layered materials, ferroelectrics, silicates, and glasses. The final section is dedicated to the latest applications of NMR in heterogeneous oxide catalysis.

MULTINUCLEAR NMR STUDY OF SILICA FIBERGLASS MODIFIED WITH ZIRCONIA

O.B. Lapina, D.F. Khabibulin, V.V. Terskikh

Solid State Nucl. Magn. Reson., 39(3-4) (2011) pp. 47-57.

Silica fiberglass textiles are emerging as uniquely suited supports in catalysis which offer unprecedented flexibility in designing advanced catalytic systems for chemical and auto industries. During manufacturing fiberglass materials are often modified with additives of various nature to improve glass properties. Glass network formers, such as zirconia and alumina, are known to provide the glass fibers with higher strength and to slow down undesirable devitrification processes. In this work multinuclear 1H, 23Na, 29Si, and 91Zr NMR spectroscopy was used to characterize the effect of zirconia on the molecular-level fiberglass structure. 29Si NMR results help in understanding why zirconia-modified fiberglass is more stable towards devitrification comparing with pure silica glass. Internal void spaces formed in zirconia-silica glass fibers after acidic leaching correlate with sodium and water distributions in the starting bulk glass as probed by 23Na and 1H NMR. These voids spaces are important for stabilization of catalytically active species in the supported catalysts. Potentials of high-field 91Zr NMR spectroscopy to study zirconia-containing glasses and similarly disordered systems are illustrated.

MECHANOCHEMICAL SYNTHESIS OF γ-LiAlO2 STUDIED BY 6Li AND 27Al NMR AND SYNCHROTRON X-RAY DIFFRACTION

V.P. Isupov*, O.A. Kharlamova*, L.E. Chupakhina*, M.R. Sharafutdinov*, D.F. Khabibulin, O.B. Lapina (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia)

Inorg. Mater., 47(7) (2011) pp. 763-767.

The structural transformations accompanying the mechanochemical synthesis of fine-particle γ-LiAlO2 have been studied by 6Li and 27Al NMR and in situ X-ray diffraction. Mechanical activation of a mixture of aluminum hydroxide and lithium carbonate in an AGO-2 planetary mill results not only in size reduction, intermixing, and partial amorphization of the starting materials but also in the mechanochemical synthesis of a carbonate form of aluminum lithium hydroxide. Subsequent heat treatment of the mechanically activated mixture leads to the release of water and carbon dioxide molecules and the formation of an X-ray amorphous phase containing aluminum in octahedral and tetrahedral oxygen coordination. The X-ray amorphous material converts to gamma lithium aluminate through an intermediate phase.

BOROTUNGSTATE POLYOXOMETALATES: MULTINUCLEAR NMR STRUCTURAL CHARACTERIZATION AND CONVERSIONS IN SOLUTIONS

R.I. Maksimovskaya, G.M. Maksimov

Inorg. Chem., 50(11) (2011) pp. 4725-4731.

The unique heteropolyanion [H3BW13O46]8– (BW13), previously suggested on the basis of indirect evidence, and protonated lacunary heteropolyanion [HBW11O39]8– (BW11) have been identified in aqueous solutions at pH 5–7.5 from NMR spectra. The pattern of tungsten–tungsten connectivities based on the analysis of the 2JW–O–W coupling satellites in the 183W NMR spectrum of BW11, containing six peaks of relative intensities ~2:2:2:1:2:2, indicates that the latter is the α isomer. The 17O NMR spectrum confirms the protonated state of the polyanion with the proton delocalized on two out of four terminal O atoms surrounding the tungsten vacancy. The 183W NMR spectrum of BW13 contains seven peaks of relative intensities ~2:1:2:2:2:2:2 with additional large couplings due to the connectivity between BW11 and [W2O7]2– fragments. According to the 17O NMR spectrum, two protons of [BW13O46H3]8– are delocalized on the two terminal trans O atoms of the dimeric fragment while the third one is linked to its bridging O atom. The conversions of BW11 and BW13 in solution were followed by using 183W NMR spectra at a “fingerprint” level. In the pH range from ~7.5 to 6, BW11 transforms to BW13, transforming further to [BW12O40]5– (BW12) and [B3W39O132Hn]n-21 (B3W39) in different ratios. Conversion of BW13 to BW12 proceeds through an intermediate complex of suggested composition [BW11O39·WO2]7–. At high acidity (pH ~0), B3W39 gradually decomposes into tungstic acid, BW12 and H3BO3. Polyanion BW12 persists in the pH range ~0–7.5.

A STUDY OF THE HYDROLYSIS OF ZrF62-AND THE STRUCTURE OF INTERMEDIATE HYDROLYSIS PRODUCTS BY 19F AND 91Zr NMR IN THE 9.4 T FIELD

M.A. Fedotov, A.V. Belyaev* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Struct. Chem., 52(1) (2011) pp. 69-74.

The high-field 19F and 91Zr NMR method is used to study the hydrolysis and polycondensation of hexafluorozirconate ZrF62- in aqueous and water-peroxide solutions. During hydrolysis in aqueous solutions only ZrF62- and F- ions were observed by NMR, however, in the water-peroxide medium, an intermediate product of hydrolysis ([F5Zr-OO-ZrF5]4-dimer) was detected. The dimer structure is confirmed by 19F and 91Zr NMR. In high fields (19F NMR frequency > 200 MHz), the fluorine exchange between ZrF62- and F- is slow in the 19F NMR scale and has a multisite character.

SOLID-PHASE CONDENSATION OF RHODIUM(III) AQUA SULFATES

S.N. Vorob’eva*, A.V. Belyaev*, M.A. Fedotov, I.V. Yushina*, T.I. Nedoseikina* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Russ. J. Inorg. Chem., 56(10) (2011) pp. 1609-616.

Solid-phase condensation of rhodium(III) aqua sulfates yielding oligomeric rhodium(III) aqua sulfate complexes was revealed. The isothermal dehydration of rhodium(III) aqua sulfates under thermal diffusion conditions in the temperature range 100–130°C was studied, and effective rate constants and activation energies were determined. The solid phases of dehydration products were studied by X-ray powder diffraction and IR spectroscopy, and solutions of polymeric phases were studied by 103Rh and 17O NMR, electronic absorption spectroscopy, chromatography, and electrophoresis.

PLATINUM(IV) COMPLEXATION WITH THE NITRATE ION IN AQUEOUS SOLUTIONS ACCORDING TO 195Pt, 15N, 14N, AND 17O NMR DATA

A.V. Belyaev*, M.A. Fedotov, S.N. Vorobieva* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Russ. J. Coord. Chem., 37(4) (2011) pp. 281-287.

Solutions of platinum(IV) nitrate were studied by 195Pt, 15N, 14N, and 17O NMR and IR and Raman spectroscopy. It was found that in nitric acid, two interrelated systems of nitrate complexes, mono- and polynuclear ones, coexist. The complexes predominating in concentrated solutions are [Pt2(μ-OH)(μ-NO3)(NO3)2(H2O)6-x(OH)x](4-x)+, [Pt4(μ-OH)3(μ-NO3)3(NO3)3(H2O)9-x(OH)x](7-x)+, [Pt4(μ-OH)4(μ-NO3)2(NO3)4(H2O)8-x(OH)x](6-x)+, and [Pt4(μ-OH)6(NO3)3(H2O)16-x(OH)x ](7-x)+.

THE INFLUENCE OF AN EXOTHERMIC REACTION ON THE SPATIAL DISTRIBUTION OF THE LIQUID PHASE IN A TRICKLE BED REACTOR: DIRECT EVIDENCE PROVIDED BY NMR IMAGING

A.A. Lysova, A. Von Garnier*, E.H. Hardy**, R. Reimert*, I.V. Koptyug*** (*Karlsruhe Institute of Technology, Karlsruhe, Germany; **International Tomography Center, Novosibirsk, Russia)

Chem. Eng. J., 173(2) (2011) pp. 552-563.

In this paper, NMR imaging was applied to study the distribution of the liquid phase in a fixed catalyst bed of an operating multiphase reactor with a cocurrent gas-liquid flow under conditions when the heterogeneous catalytic hydrogenation of 1-octene was taking place in the reactor. The 2D maps of the spatial distribution of the external and internal liquid holdups in the various regimes of the catalyst bed operation have been obtained for the first time in the course of the reaction. It was shown by a direct in situ method that an exothermic reaction taking place in a trickle bed reactor dramatically affected the distribution of the liquid phase in the catalyst bed. In particular, in the presence of the reaction, the catalyst bed was characterized by a non-uniform distribution of the liquid phase, as revealed by evaluating the external and internal liquid holdups. In the absence of the reaction, the bed was largely filled with the liquid phase.

PROBING THE DYNAMICS OF CO2 AND CH4 WITHIN THE POROUS ZIRCONIUM TEREPHTHALATE UiO-66(Zr): A SYNERGIC COMBINATION OF NEUTRON SCATTERING MEASUREMENTS AND MOLECULAR SIMULATIONS

Q. Yang*,****, H. Jobic**, F. Salles*, D.I. Kolokolov, V. Guillerm***, Ch. Serre***, G. Maurin* (*Institut Charles Gerhardt Montpellier, Universit Montpellier II, Montpellier CEDEX, France; **Institut de Recherches sur la Catalyse et l’Environnement de Lyon, Villeurbanne, France; ***Institut Lavoisier, Versailles, France; ****Beijing University of Chemical Technology, Beijing, P.R. China)

Chem. Eur. J., 17(32) (2011) pp. 8882-8889.

Quasi-elastic neutron scattering (QENS) measurements combined with molecular dynamics (MD) simulations were conducted to deeply understand the concentration dependence of the self-and transport diffusivities of CH4 and CO2, respectively, in the humidity-resistant metal–organic framework UiO-66(Zr). The QENS measurements show that the self-diffusivity profile for CH4 exhibits a maximum, while the transport diffusivity for CO2 increases continuously at the loadings explored in this study. MD simulations can reproduce fairly well both the magnitude and the concentration dependence of each measured diffusivity. The flexibility of the framework implemented by deriving a new forcefield for UiO-66(Zr) has a significant impact on the diffusivity of the two species. Methane diffuses faster than CO2 over a broad range of loading, and this is in contrast to zeolites with narrow windows, for which opposite trends were observed. Further analysis of the MD trajectories indicates that the global microscopic diffusion mechanism involves a combination of intracage motions and jump sequences between tetrahedral and octahedral cages.

NMR IMAGING OF HEAVY CRUDE OIL FOR SOFTENING DETECTION UNDER HEAT TREATMENT

E.V. Morozov*, O.N. Martyanov, N.V. Volkov*, O.V. Falaleev* (*Kirensky Institute of Physics, Krasnoyarsk, Russia)

J. Mater. Sci. Eng. A, 1 (2011) pp. 545-551.

NMR imaging results of Mongolian heavy crude oil samples subjected to heat treatment are presented in this work. Abundance of dotted inhomogeneities related with high paraffinicity of heavy oil was obtained during imaging investigation. Behavior of heavy oil subjected to heat treatment, dotted inhomogeneities changes, softening and dynamic of melting front were visualized by means of imaging techniques based on both gradient and spin echo. Softening forestalling over the melting front are demonstrated using artificial mark in the form of water drop deposited on the oil surface. In results the NMR imaging proved to be highly effective for investigation of impurity agglomerates in heavy oil engineering development.

ELECTRON SPIN RESONANCE OF VO2+ RADICAL-ION IN SUB- AND SUPERCRITICAL WATER

S.N. Trukhan, V.F. Yudanov, O.N. Martyanov

J. Supercrit. Fluids, 57(3) (2011) pp. 247-250.

Electron spin resonance (ESR) spectra of VO2+ radical-ions in sub- and supercritical water are observed. Upon increasing the temperature from 20 to 100°C, the fine structure line widths in the ESR spectra of the vanadyl ion are observed to be reduced that is associated with the effective averaging of the g-factor anisotropy and the hyperfine interaction. With further increasing the temperature, the spectrum components of the hyperfine structure are broadened significantly resulting in the unresolved low-intensity line in supercritical water with ΔHpp ∼ 300 G. The data obtained allow behavior peculiarities of the paramagnetic VO2+ ions in sub- and supercritical water including rotational dynamics and spin exchange between the radicals to be elucidated. The registration of the unresolved low-intensity line in supercritical conditions points to an increase in the local ion concentration in the system that can be an initial stage for the formation of vanadium-based particles in supercritical conditions. The study demonstrates that ESR is the powerful tool to investigate properties of sub- and supercritical water in situ.

THE CHARACTERISTICS OF NEW PERMANENT SORBENT–MODIFIERS FOR THE HYDRIDE ATOMIC ABSORPTION SPECTROMETRIC DETERMINATION OF ARSENIC WITH TRAPPING OF THE ARSINE IN A GRAPHITE FURNACE

M.Yu. Burylin*, V.I. Zaikovsky, K.A. Romanovsky*, P.R. Arushanian* (*Kuban

State University, Krasnodar, Russia)

Anal. & Control, 15(1) (2011) pp. 23-36.

The characteristics of new Zr–Ir and W–Ir permanent sorbent–modifiers on the carbonized basis for the determination of arsenic by electrothermal atomic absorption spectrometry (ETAAS) with trapping within a graphite (GF) furnace were studied. The results of the electron microscopic investigation, local X-ray elemental analysis and electron microdiffraction corroborated zirconium and tungsten carbide’s formation. The particle sizes of these

compounds are from 50 to 200 nm. The iridium component presents as nanoparticles (5-10 nm) of condensed systems with the carbide forming metal. There is even distribution of the particles on the basis. Achievement of necessary purity’s level of the permanent systems during their synthesis in a graphite furnace is confirmed. The parameters of the stage of arsine trapping by new sorbent-modifiers and arsenic’s atomization stage are studied: temperature of trapping stage, velocity of reagent’s entering, time of trapping stage, temperature of atomization stage. The optimized conditions were used for the determination of As in natural surface-water. The limits of detection were 7 ng/l and 5 ng/l for the Zr-Ir modifier and W-Ir modifier respectively.

METHANE CONVERSION INTO AROMATIC HYDROCARBONS OVER Ag–Mo/ZSM-5 CATALYSTS

A.V. Vosmerikov*, V.I. Zaikovsky, L.L. Korobitsyna*, V.V. Kozlov*, N.V. Arbuzova*, S.P. Zhuravkov** (*Institute of Petroleum Chemistry, Tomsk, Russia; **Tomsk Polytechnic University, Tomsk, Russia)

Kinet. Catal., 52(3) (2011) pp. 427-433.

Nonoxidative methane conversion into aromatic hydrocarbons over ZSM-5-type high-silica zeolites modified with nanosized powders of molybdenum (4.0 wt%) and silver (0.1–0.5 wt%) is reported. The acidic properties of the catalysts have been investigated by temperature-programmed ammonia desorption. The microstructure and composition of the Ag-Mo/ZSM-5 catalytic systems have been studied by high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The doping of the Mo containing zeolite with silver enhances its activity and stability in nonoxidative methane conversion into aromatic hydrocarbons.

SUBMICROMETER INTERMEDIATES IN THE CITRATE SYNTHESIS OF GOLD NANOPARTICLES: NEW INSIGHTS INTO THE NUCLEATION AND CRYSTAL GROWTH MECHANISMS

Yu.L. Mikhlin*, A.A. Karacharov*, M.N. Likhatski*, T.Yu. Podlipskaya**, Ya.V. Zubavichus***, A.A. Veligzhanin***, V.I. Zaikovsky (*Institute of Chemistry and Chemical Technology, Krasnoyarsk, Russia; **Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; ***National Research Centre “Kurchatov Institute”, Moscow, Russia)

J. Colloid Interf. Sci., 362(2) (2011) pp. 330-336.

The reduction of tetrachloroaurate by citrate ions in aqueous solutions yielding gold nanoparticles (GNPs) has been studied using in situ tapping mode atomic force microscopy (AFM), UV-vis absorption and dynamic light scattering (DLS) spectroscopies, small-angle X-ray scattering (SAXS) along with ex situ TEM, EDX and XPS. Special attention is given to mesoscale intermediates responsible for the intense coloring of the transient solutions and their role in nucleation and crystal growth. AFM detects liquid droplet-like domains, globules 30-50 nm in diameter arranged in submicrometer aggregates in the gray and blue solutions, and well separated individual particles in the final red sols. DLS shows abrupt appearance of species about 30 nm and larger but not growing Au nanoparticles, while SAXS reveals gradually increasing nanoparticles and no aggregates. The mesoscale structures observed in TEM become looser as the reaction proceeds; they contain signatures of oxidized Au and other solutes. The results are interpreted in terms of decomposition of supersaturated solutions to afford domains (“dense droplets”) enriched by gold, and then, after nucleation and coalescence of Au nuclei inside them, rather slow growth of gold nanoparticles within the associated globules; the color changes of the transient solutions are due to increasing interparticle distances.

KINETICS AND MECHANISM OF THE GROWTH OF GOLD NANOPARTICLES BY REDUCTION OF TETRACHLOROAURIC ACID BY HYDRAZINE IN Triton N-42 REVERSE MICELLES

V.V. Tatarchuk*, A.P. Sergievskaya*, I.A. Druzhinina*, V.I. Zaikovsky (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Nanopart. Res., 13(10) (2011) pp. 4997-5007.

The kinetics of the growth of gold nanoparticles during the reduction of tetrachloroauric acid by hydrazine in dispersed aqueous solution encapsulated by reverse micelles of Triton N-42 surfactant (with decane as dispersion medium) was studied by means of spectrophotometry. According to DLS data, at a set value of solubilization capacity Vs/Vo = 0.005 initial micelles have an aqueous core hydrodynamic diameter dc = 3.6±0.2 nm. The final particles obtained after full reduction of AuIII have a metallic core of defect-free single-crystalline gold with a narrow size distribution and average core diameter dAu = 7.7 ± 1.4 nm as shown by TEM. The rate of the particle growth is limited by the rate of gold reduction. The process kinetics corresponds to the model consisting of two stages of reduction AuIII → AuI → Au0. The stages involve the formation and redox decay of the intermediate complexes Au(N2H4)Cl3 and Au(N2H4)Cl, and each stage proceeds via two routes:

  1. homogeneous in the dispersed aqueous phase, and
  2. heterogeneous on the particle surfaces. Reactions taking route (2) are autocatalytic because they proceed with participation of the surface atoms of particles as the final products of AuIII reduction. The dependencies of observed rate constants on reagent concentrations, temperature, and solubilization capacity of the micellar solution are studied.

THE AGEING OF SILICA GELS AFFECTED BY HYDROTHERMAL TREATMENT

W. Lutz*, M. Weber**, R. Bertram***, R. Kurzhals****, G.N. Kryukova

(*Brandenburgische Technische Universität Cottbus, Berlin, Germany; **SCW Process Technology Development GmbH, Berlin, Germany; ***Leibniz-Institut für Kristallzüchtung, Berlin, Germany; ****Süd-Chemie Zeolites GmbH, Bitterfeld-Wolfen, Germany)

Z. Anorg. Allg. Chem., 637(3-4) (2011) pp. 421-425.

Commercial silica gels of the pyrogenic and precipitated types were hydrothermally treated for 72 hours at temperatures between 90°C and 210°C in water of autogenous pressure. The samples were characterised by IR spectroscopy, water and nitrogen adsorption. Stability and sorption capacity run similarly. The more Q4 (Si(OSi)4) building units the framework of a silica gel contained, the lower was its sorption capacity. Sorption capacity increased with rising number of structural defects characterised by the presence of Q3 (Si(OSi)3OH) and Q2 (Si(OSi)2(OH)2) groups. Simultaneously, the hydrothermal stability of the silica material dropped off.

REACTIVITY OF EXTRA-FRAMEWORK SPECIES OF USY ZEOLITES IN ALKALINE MEDIUM

W. Lutz*, R. Bertram**, D. Heidemann***, R. Kurzhals****, C. Ruscher*****, G.N. Kryukova (*Lehrstuhl fur Luftchemie und Luftreinhaltung Brandenburgische Technische Universitat Cottbus, Berlin, Germany; **Leibniz-Institut fur Kristallzuchtung, Berlin, Germany; ***Institut fur Chemie Humboldt-Universitat zu Berlin, Berlin, Germany; ****Sud-Chemie Zeolites GmbH, Bitterfeld-Wolfen, Germany; *****Universitat Hannover, Hannover, Germany)

Z. Anorg. Allg. Chem., 637(1) (2011) pp. 75-82.

Zeolites of type USY (ultra-stable Y) were obtained by steaming of NH4NaY modification. Samples were modified by subsequent alkaline treatment in KOH solution. USY and USY-KOH were characterised by chemical element analysis, XRD, IR, 29Al and 29Si MAS NMR spectroscopic measurements. Correct silicon to aluminium ratios (Si/Al) were determined by XRD and IR (double ring vibration wDR) data whereas values calculated according to data of 29Si MAS NMR and IR spectroscopy (asymmetrical TOT valence vibration wTOT) appeared to be too high. In the latter case, the signals of the zeolite framework were strongly superimposed by that of extra-framework silica gel (EFSi) formed during steaming. It was found that alkaline leaching induces desilication of silicon-rich area of the zeolite framework and partial dissolution of EFSi. Silicate ions of both react with likewise dissolved extra-framework aluminium (EFAl) to form X-ray amorphous aluminosilicate. Consequently, the superposition of the 29Si MAS NMR signals of the zeolite framework by silica gel was reduced for Q4(0Al) but increased for Q4 (2Al) and Q4(3Al) structure units. A reinsertion of EFAl into the zeolite framework has not been observed.

LIGHT SCATTERING IN A SURFACE GLASS LAYER PRODUCED BY A SURFACE ION EXCHANGE PROCESS AND COATED WITH THIN GOLD LAYERS

O.N. Sidel’nikova*, G.A. Pozdnyakov**, A.N. Serkova, A.N. Salanov (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **Khristianovich Institute of Theoretical and Applied Mechanics, Novosibirsk, Russia)

Glass Technol., 52(1) (2011) pp. 15-22.

The morphology and optical properties of a glass surface treated by a surface ion exchange process and coated with a thin surface gold layer are investigated. It was found by SEM that the modified surface layer consists of a system of microblocks and microcracks. In addition the thin gold layer consists of nanosized hemispherical gold nucleation centers of volume growth (diameters ∼100-500 nm), three-dimensional gold aggregates and pendant “cornice”. The investigated optical properties (light scattering, depolarization, light loss characteristics and effectiveness of light propagation) differ significantly from the analogous optical data previously reported for glass surface modified by the same surface ion exchange process but lacking the thin gold layer. The results are also compared with results obtained from a chemically etched glass surface. The obtained data may be important and useful in glass illumination engineering, light decoration and others fields.

METHOD OF SPECTRAL SUBTRACTION OF GAS-PHASE FOURIER TRANSFORM INFRARED (FT-IR) SPECTRA BY MINIMIZING THE SPECTRUM LENGTH

D.V. Kozlov, A.S. Besov

Appl. Spectrosc., 65(8) (2011) pp. 918-923.

A new method of spectral subtraction for gas-phase Fourier transform infrared (FT-IR) spectra was developed for long-path gas measurements. The method is based on minimization of the length of the spectrum that results from subtracting the spectrum of an individual component of a gas mixture (water, CO2, etc.) from the experimental spectrum of the mixture. For this purpose a subtraction coefficient (kmin) is found for which the length of the resulting spectrum is minimized. A mathematical simulation with two Lorentzian absorption bands was conducted and the limits of application for the proposed method were determined. Two experimental examples demonstrate that a successful result could be achieved in the case when the subtrahend spectrum contains a number of narrow absorption bands (such as the spectrum of water vapor).

In situ FTIR STUDY OF β-PICOLINE TRANSFORMATIONS ON V–Ti–O CATALYSTS

G.B. Chernobay, Yu.A. Chesalov, V.P. Baltakhinov, G.Ya. Popova, T.V. Andrushkevich

Catal. Today, 164(1) (2011) pp. 58-61.

Surface complexes formed during β-picoline transformations on V–Ti–O catalysts in the temperature range of 120–300°C were studied using in situ FTIR spectroscopy. Two vanadia–titania catalysts with several kinds of vanadia species were used in experiments. FTIR spectra have revealed differences in composition of surface complexes under different coverage, which could be related to different ways of transformations of intermediate pyridine-3-carbaldehyde.

O RADICAL ANIONS ON OXIDE CATALYSTS: FORMATION, PROPERTIES, AND REACTIONS

A.M. Volodin, S.E. Malykhin, G.M. Zhidomirov

Kinet. Catal., 52(4) (2011) pp. 605-619.

A systematic in situ EPR study of processes yielding O radical anions on the surface of oxide dielectrics (MgO, CaO), semiconductors (ZnO, TiO2), supported systems (V/SiO2), and zeolite FeZSM-5 is reported. Methodological approaches to the study of O radical anions are considered for the cases in which these species are directly undetectable by EPR. Particular attention is focused on the development of methods of investigation of so-called α-oxygen on the FeZSM-5 surface, which is an O radical anion stabilized on the paramagnetic ion Fe3+. The reactions involving α-oxygen and the analogous reactions known for O radical anions stabilized on the oxide surface are demonstrated to occur in similar ways. The photostimulated formation of spatially separated electron and hole centers on the surface of oxide systems is most likely due not to charge separation, but to the spatial separation of the radicals resulting from the homolytic photodissociation of chemisorbed water. A scheme is suggested for this process on the partially hydroxylated MgO surface.

EXPLORING BY PULSED EPR THE ELECTRONIC STRUCTURE OF UBISEMIQUINONE BOUND AT THE QH SITE OF CYTOCHROME bo3 FROM ESCHERICHIA COLI WITH in vivo 13C-LABELED METHYL AND METHOXY SUBSTITUENTS

M.T. Lin*, A.A. Shubin, R.I. Samoilova**, K.V. Narasimhulu*, A. Baldansuren*, R.B. Gennis*, S.A. Dikanov (*University of Illinois at Urbana-Champaign, Urbana, Illinois; **Institute of Chemical Kinetics and Combustion, Novosibirsk, Russia)

J. Biol. Chem., 286(12) (2011) pp. 10105-10114.

The cytochrome bo3 ubiquinol oxidase from Escherichia coli resides in the bacterial cytoplasmic membrane and catalyzes the two-electron oxidation of ubiquinol-8 and four-electron reduction of O2 to water. The one-electron reduced semiquinone forms transiently during the reaction, and the enzyme has been demonstrated to stabilize the semiquinone. The semiquinone is also formed in the D75E mutant,

where the mutation has little influence on the catalytic activity, and in the D75H mutant, which is virtually inactive. In this work, wild-type cytochrome bo3 as well as the D75E and D75H mutant proteins were prepared with ubiquinone-8 13C-labeled selectively at the methyl and two methoxy groups. This was accomplished by expressing the proteins in a methionine auxotroph in the presence of l-methionine with the side chain methyl group 13C-labeled. The 13C-labeled quinone isolated from cytochrome bo3 was also used for the generation of model anion radicals in alcohol. Two-dimensional pulsed EPR and ENDOR were used for the study of the 13C methyl and methoxy hyperfine couplings in the semiquinone generated in the three proteins indicated above and in the model system. The data were used to characterize the transferred unpaired spin densities on the methyl and methoxy substituents and the conformations of the methoxy groups. In the wild type and D75E mutant, the constraints on the configurations of the methoxy side chains are similar, but the D75H mutant appears to have altered methoxy configurations, which could be related to the perturbed electron distribution in the semiquinone and the loss of enzymatic activity.

SIZE-DEPENDENT EFFECTS IN EPR AND LUMINESCENCE SPECTRA OF NH4BPh4 EXCITED STATES: FROM BULK TO NANOPARTICLES

O.V. Antonova*, V.A. Nadolinny*, E.A. Il'inchik*, M.K. Kovalev, A.P. Yelisseyev** (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Institute of Geology & Mineralogy, Novosibirsk, Russia)

Appl. Magn. Reson., 40(4) (2011) pp. 459-469.

Photoexcited states of NH4BPh4 (TPhBA) particles embedded in mesoporous frameworks of different pore sizes were studied by combined electron paramagnetic resonance (EPR), optical and photoluminescence techniques. A distribution of triplet states with short and long electron-hole distances was found. While EPR studies on TPhBA bulk sample suggested that the formation of electron-hole pairs upon the excitation was caused by electron capture on electron traps, the samples in mesoporous frameworks exhibit two ways of the pair formation. The first one is attributed to the capture on phenyl rings and another one is to be thought as the capture of electrons on adsorbed oxygen molecules. These results are also consistent with the thermoluminescence spectra and EPR studies of the photoexcited samples during annealing.

EFFECT OF Cs+ PROMOTER IN Ru/MgO CATALYSTS

Yu.V. Larichev

J. Phys. Chem. C, 115(3) (2011) pp. 631-635.

Ru/MgO and Ru-Cs+/MgO catalysts were prepared from Ru(OH)Cl3 and were studied by XPS, TEM, CO chemisorption, and EXAFS. An explanation for the large differences in sizes of Ru particles measured by TEM and XRD compared to those determined by CO chemisorption is proposed. This explanation is based on the XPS data that the initial catalyst Ru/MgO consists of Ru0 metal particles and RuO2 clusters. The latter are not measured by CO chemisorption and have high stability due to RuO2-MgO interaction. A new feature of Cs+ promoter influence on the Ru/MgO catalyst was found. The addition of Cs+ to the Ru/MgO catalyst, which contains Ru partly in the oxidized form, does not lead to the formation of any cesium ruthenates. Instead, the cesium promoter reduces the RuO2 clusters, which are stabilized by epitaxy interaction with the support, to form the Ru0 particles. This new feature of Cs+ promoter results in the increase of supported Ru useful ratio and Ru-specific surface area in these catalysts.

ELECTRONIC STATE OF RUTHENIUM DEPOSITED ONTO OXIDE SUPPORTS: AN XPS STUDY TAKING INTO ACCOUNT THE FINAL STATE EFFECTS

Yu.V. Larichev, B.L. Moroz, V.I. Bukhtiyarov

Appl. Surf. Sci., 258(4) (2011) pp. 1541-1550.

The electronic state of ruthenium in the supported Ru/EOx (EOx = MgO, Al2O3 or SiO2) catalysts prepared with the use of Ru(OH)Cl3 or Ru(acac)3 (acac = acetylacetonate) and reduced with H2 at 723 K is characterized by X-ray photoelectron spectroscopy (XPS) in the Ru 3d, Cl 2p and O 1s regions. The influence of the final state effects (the differential charging and variation of the relaxation energy) on the binding energy (BE) of Ru 3d5/2 core level measured for supported Ru nanoparticles is estimated by comparison

of the Fermi levels and the modified Auger parameters determined for the Ru/EOx samples with the corresponding characteristics of the bulk Ru metal. It is found that the negative shift of the Ru 3d5/2 peak which is observed in the spectrum of ruthenium deposited onto MgO (BE = 279.5–279.7 eV) with respect to that of Ru black (BE = 280.2 eV) or ruthenium supported on γ-Al2O3 and SiO2 (BE = 280.4 eV) is caused not by the transfer of electron density from basic sites of MgO, as considered earlier, but by the differential charging of the supported Ru particles compared with the support surface. Correction for the differential charging value reveals that the initial state energies of ruthenium in the Ru/EOx systems are almost identical (BE = 280.5 ± 0.1 eV) irrespectively of acid–base properties of the support, the mean size of supported Ru crystallites (within the range of 2–10 nm) and the surface Cl content. The results obtained suggest that the difference in ammonia synthesis activity between the Ru catalysts supported on MgO and on the acidic supports is accounted for by not different electronic state of ruthenium on the surface of these oxides but by some other reasons.

SMALL-ANGLE SCATTERING STUDY OF COLLOIDAL PARTICLES IN HEAVY CRUDE OILS

F.V. Tuzikov, Yu.V. Larichev, L.S. Borisova*, I.V. Kozhevnikov, O.N. Martyanov (*Trofimuk Institute of Petroleum Geology and Geophysics, Novosibirsk, Russia)

Pet. Chem., 51(4) (2011) pp. 281-285.

The structural and dispersion characteristics of samples of heavy crude oils and fractions isolated from them have been studied. A method of in situ analysis of the aggregation of asphaltenes directly in crude oils on the basis of small-angle X-ray scattering is proposed. It has been shown that the maximum size of scattering particles in all crude oil samples is limited to the value on the order of 8.0 nm; the average diameter is ~2.0 nm. It has been found that the fraction with sizes of 0.8–2.5 nm is mostly composed of resins. Asphaltenes in crude oils form larger aggregated particles with a size up to 8 nm. A comparative study of model dilute solutions of asphaltenes in toluene (0.23 wt%) has shown that the major part of asphaltenes in the liquid (~94%) is in the form of individual molecules with a size of 0.4–1.2 nm, and only an insignificant remaining part (~6%) occurs in the form of large aggregates.

 

INFLUENCE OF ATORVASTATIN ON SERUM LIPIDS ON MICE WITH LIPEMIA

V.M. Loginova*, F.V. Tuzikov, N.A. Tuzikova, M.S. Cherkanova*, E.E. Filyushina*, T.A. Korolenko* (*Institute of Physiology, Novosibirsk, Russia)

Bull. SB RAMS, 31(2) (2011) pp. 133-137.

Atorvastatin (75 mg/kg) was administered twice in ICR mice with acute lipemia induced with a single injection of Triton WR 1339 (500 mg/kg). A novel small-angle X-ray scattering (SAXS) method for the determination of fractional and subfractional composition of C-LP was used. In Triton WR 1339-treated animals, there was a drastic increase of atherogenic low-density C-LP (C-LDL) fraction, intermediate density lipoprotein-cholesterol (C-IDL) subfraction, and very low-density C-LP (C-VLDL) fractions (C-VLDL3-5 subfraction), with an increase of the C-HDL3 subfraction. Atorvastatin treatment of lipemia was followed a decrease in the total C and, especially, a decrease in the TG concentration, by normalization of atherogenic C-LDL fraction, C-IDL subfraction, and a decrease of C-VLDL (C-VLDL3-5 subfraction).

INFLUENCE OF ATORVASTATIN ON FRACTIONAL AND SUBFRACTIONAL COMPOSITION OF SERUM LIPOPROTEINS AND MMP ACTIVITY IN MICE WITH TRITON WR 1339-INDUCED LIPAEMIA

T.A. Korolenko*, M.S. Cherkanova*, F.V. Tuzikov, T.P. Johnston**, N.A. Tuzikova, V.M. Loginova*, V.I. Kaledin* (*Institute of Physiology, Novosibirsk, Russia; **University of Missouri-Kansas City, Kansas City, Missouri, USA)

J. Pharm. Pharmacol., 63(6) (2011) pp. 833-839.

The effects of atorvastatin on the atherogenic and anti-atherogenic lipoprotein-cholesterol (C-LP) and lipoprotein-triglyceride (TG-LP) fractions and subfractions at the early stage of murine acute hyperlipidaemia, and its pleiotropic anti-inflammatory effects via the activity of matrix metalloproteinases (MMPs) were studied.

Atorvastatin (75 mg/kg) was administered to ICR mice with acute lipaemia induced by a single injection of Triton WR 1339 (500 mg/kg). A novel small-angle X-ray scattering (SAXS) method was used for the determination of the fractional and subfractional composition of C-LP and TG-LP. In Triton WR 1339-treated mice, there was a drastic increase in the atherogenic low-density C-LP (C-LDL) fraction, intermediate density lipoprotein-cholesterol (C-IDL) subfraction, and very low-density C-LP (C-VLDL) fractions (C-VLDL(3-5) subfraction). Additionally, there was an increase in the C-HDL(3) subfraction. Treatment of lipaemia with atorvastatin resulted in the normalization of the atherogenic C-LDL fraction and the C-IDL subfraction. A decrease in C-VLDL (C-VLDL(3-5) subfraction), total cholesterol and, especially, triglyceride (TG) concentrations was also demonstrated. Similar results were obtained with the TG-LP fractions and subfractions. Additionally, atorvastatin treatment resulted in an increase in the serum and liver MMP activity.

STUDY OF CdSe/CdS QUANTUM DOTS IN SOLUTIONS AND GELS BY SMALL-ANGLE X-RAY SCATTERING

N.B. Simonova*, F.V. Tuzikov, R.N. Khramov*, N.A. Tuzikova, M.F. Tuzikov*, M.S. Vakshtein**

(*Institute of Theoretical and Experimental Biophysics, Pushchino, Moscow oblast, Russia; **Federal State Unitary Association Research Institute of Applied Acoustics, Dubna, Moscow oblast, Russia)

J. Surf. Invest. - X-Ray Synchrotron Neutron Techn.,

5(1) (2011) pp. 126-133.

The sizes of semiconductor nanocrystals of CdSe/CdS quantum dots (QDs) synthesized by the colloidal method were estimated using small-angle X-ray scattering. The distribution of QD nanocrystals in organic solvents of different polarities and in polymer gels and matrices is studied. Structural invariants of scattering QD particles (heterogeneities of the electron density) — namely, inertia radii and sizes, forms, and dispersive composition of particles — are determined. The contribution of scattering by QDs in solutions and gels is calculated. The effective sizes of particles and their aggregates are determined, and the parameters of the distribution over the QD sizes in organic solvents and polymer matrices are estimated. The typical distance between particles in samples is determined. The position of the maximum at the beginning of the small-angle scattering curves corresponds to the distance dm = 2π/h0 between the planes (here, h0 is the position of the maximum on the

scale h). It is 74–76.9 Å for solutions, 60 Å for gels, and 99 Å for polymer matrices with concentrations of up to 0.15% and 77 Å for those with the concentrations exceeding 0.15%, which is close to the estimation of the sizes of separate CdSe QDs that was obtained from the distribution histograms (60–80 Å). This result shows that CdSe/CdS QDs introduced in the polymer matrices disperse to form either separate particles or small aggregates and located at a distance on the order of 80 Å from each other.

SPECIFIC FEATURES OF ASSOCIATION OF Cu2+ IONS IN CONCENTRATED AQUEOUS AMMONIA SOLUTIONS OF COPPER NITRATE AS PROBED BY ESR

V.F. Anufrienko, G.A. Zenkovets, R.A. Shutilov, V.Yu. Gavrilov, N.T. Vasenin, A.A. Shubin, Z.R. Ismagilov, V.N. Parmon

Doklady Phys. Chem., 440(2) (2011) pp. 194-197.

In this work, self-association of Cu2+ ions in aqueous ammonia solutions of copper nitrate was revealed for the first time.

It was shown that, in aqueous ammonia solutions of copper nitrate containing 10 g/L Cu in a wide range of ammonium ion concentrations, different types of Cu2+ associates with specific orbital ordering were formed. The ammonium concentration in a solution has a decisive effect on the type of orbital ordering of Cu2+ ions in associates. In all cases, copper ion ordering in associates is caused by the presence of bridging OH groups in the axial or equatorial position of [Сu(NH3)n(H2O)6–n]2+ complexes (n < 6).

BIMETALLIC Pd–M (M = Co, Ni, Zn, Ag) NANOPARTICLES CONTAINING TRANSITION METALS: SYNTHESIS, CHARACTERIZATION, AND CATALYTIC PERFORMANCE

B.G. Ershov*, A.V. Anan’ev*, E.V. Abkhalimov*, D.I. Kochubei, V.V. Kriventsov, L.M. Plyasova, I.Yu. Molina, N.Yu. Kozitsyna**, S.E. Nefedov**, M.N. Vargaftik**, I.I. Moiseev** (*Frumkin Institute of Physical Chemistry and Electrochemistry, Moscow, Russia; **Kurnakov Institute of General and Inorganic Chemistry, Moscow, Russia)

Nanotechn. Russia, 6(5-6) (2011) pp. 323-329.

The reductive thermolysis of Pd(OOCMe)4M(OH2) (M = NiII, CoII, ZnII) and Pd(OOCMe)4Ag2(HOOCMe)4 molecular complexes results in the generation of bimetallic Pd-based Pd–M (M = Co, Ni, Zn, Ag) nanoparticles. The composition and morphology of nanoparticles and the electron state of metal atoms were characterized using electron microscopy, elemental ICP analysis, X-ray diffraction, and XAFS (XANES/EXAFS) techniques. The catalytic performance of nanoparticles was studied using the example of reactions of catalytic hydrazine decomposition and U(VI) reduction to U(IV) by hydrazine and formic acid. The catalytic performance of Pd–Ni nanoparticles is superior to that of the standard supported Pd/SiO2 catalyst containing a similar amount of Pd atoms, while Pd–Co, Pd–Zn, and Pd–Ag Nanoparticles do not catalyze the studied reactions.

NOVEL HETEROMETALLIC PALLADIUM-SILVER COMPLEX

N.Yu. Kozitsyna*, S.E. Nefedov*, A.P. Klyagina*, A.A. Markov*, Zh.V. Dobrokhotova*, Yu.A. Velikodny**, D.I. Kochubey, T.S. Zyubina***, A.E. Gekhman*, M.N. Vargaftik*, I.I. Moiseev* (*Kurnakov Institute of General and Inorganic Chemistry, Moscow, Russia; **Moscow Lomonosov State University, Moscow, Russia; ***Institute for New Chemical Problems, Moscow Region, Chernogolovka, Russia)

Inorg. Chim. Acta, 370(1) (2011) pp. 382-387.

The reaction between Pd3(OOCMe)6 and Ag2(OOCMe)2 afforded the first palladium–silver heterometallic acetate-bridged complex PdII[(μ-OOCMe)2AgI(HOOCMe)2]2 (1).The molecular geometry and electronic structure of 1 were studied by single-crystal XRD and quantum-chemical DFT calculations. Thermal transformations of 1 in vacuo and under Ar, H2 produced PdAg alloy nanoparticles characterized with powder XRD and EXAFS.

COCATALYTIC EFFECT OF PALLADIUM AND ZINC IN THE CONDENSATION OF ALCOHOL CARBON BACKBONES INTO HYDROCARBONS

A.V. Chistyakov*, M.V. Tsodikov*, V.Yu. Murzin*, F.A. Yandieva*, Ya.V. Zubavichus**, N.Yu. Kozitsyna***,A.E. Gekhman***, V.V. Kriventsov, I.I. Moiseev*

(*Topchiev Institute of Petrochemical Synthesis, Moscow, Russia; **Kurchatov Institute Russian Research Center, Moscow, Russia; ***Kurnakov Institute of General and Inorganic Chemistry, Moscow, Russia)

Kinet. Catal., 52(2) (2011) pp. 258-272.

The results of the direct conversion of ethanol and its mixture with glycerol into a C4–C10+ alkane and olefin fraction in the presence of Pd-, Zn-, and Pd–Zn-containing catalysts, which were prepared by supporting homo- and heterometallic acetate complexes onto the surface of γ-Al2O3, are reported. It was found that, in the presence of mono- and bicomponent Pd–ZnO (Pd; ZnO)/γ-Al2O3 systems, selectivity in the formation of alkanes, olefins, or their mixtures in the target fraction can be controlled as a result of the cocatalytic effect of active components that are responsible for the catalyst activity in condensation and hydrogenation reactions. The structures of the active components were studied and the genesis of the catalytic systems was characterized using XAFS, XPS, and XRD analysis. It was found that the addition of glycerol considerably increased the yield of the target hydrocarbon fraction.

STERIC FACTOR IN LIGAND DISPLACEMENT OF ZIRCONIUM ALKOXIDES DISSOLVED IN ALCOHOLS

V.V. Kanazhevskii, Yu.A. Chesalov, N.S. Kotsarenko, D.I. Kochubey

J. Organomet. Chem., 696(9) (2011) pp. 1879-1886.

The present study indicates EXAFS direct structural data obtained for zirconium ethoxide, iso- and n-propoxide are alike those for zirconium n-butoxide complexes. This is evident for agreement of structural units of above mentioned alkoxides complexes. The structural model of n-butoxide was developed earlier. Six interconnected tetramers assemble a structural unit of the alkoxides under study. The tetramers build of zirconium atoms in the highly flattened pyramid corners. Four zirconium atoms are bonded in series by double bridges through oxygen atoms of alkoxide ligands. Two of the four zirconium atoms are bias bonded by single ligand bridges. The distances between pairs of zirconium atoms inside the tetramer are 3.3 and 3.5 angstrom. Tetramers are linked together also by a single ligand bridges. The distance between zirconium atoms of the two neighbor tetramers is 3.9 angstrom. Primary particles (tetramer sextet) form aggregates in a solution. Possible shapes of the anisotropically sized aggregates is a large diameter cylinder with small height (a disk), or a small diameter cylinder with large height (a rod). Primary particles composed through ligands. The distance between the neighbor zirconium atoms of different primary particles is 4.8 or 5.1 angstrom depending on the coordination nature and the neighboring particles number.

A HIERARCHIC STRUCTURE IN ZIRCONIUM BUTOXIDE COMPLEXES IN n-BUTANOL SOLUTIONS

V.V. Kanazhevskii, N.S. Kotsarenko, V.N. Kolomiichuk, D.I. Kochubey

J. Struct. Chem., 52(1) (2011) pp. 75-82.

The structure of particles in zirconium n-butoxide solutions in n-butyl alcohol is determined by means of EXAFS, SAXS, and molecular mechanics modeling. Zirconium atoms are found to be bonded to each other via the oxygen atom and to form large anisotropic particles in the solution. Primary particles have a shape close to spherical; their diameter together with the solvate shell is 28.9 Å. These particles then aggregate into anisotropic structures. During solution aging under normal conditions without contact with the atmosphere, the particle anisotropy increases because of the aggregation of complexes. When the solution concentration decreases, the particles are divided into primary spherical particles with a characteristic size of 28.9 Å. The described changes are confirmed by a decrease in the number of Zr-Zr distances of 4.8 Å and 5.1 Å, which according to the EXAFS data, correspond to the bonds between the primary particles. The characteristic maximum sizes of particles in solutions with concentrations from 0.1 g to 0.003 g ZrO2/ml are 160–80 Å.

TRANSPORT AND THERMAL CHARACTERISTICS OF Cs1-xRbxH2PO4

V.G. Ponomareva*, V.V. Martsinkevich*, Yu.A. Chesalov (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia)

Russ. J. Electrochem., 47(5) (2011) pp. 605-612.

The transport and thermal properties of Cs1-xRbxH2PO4 in a wide range of compositions were studied. The binary salts Cs1-xRbxH2PO4 (x = 0–0.9) contain solid solutions with a structure of CsH2PO4. The binary salts were synthesized by mechanically mixing the starting components and growing crystals by isothermal evaporation from aqueous solutions. The properties of Cs1-xRbxH2PO4 salts obtained by different procedures were found to differ considerably. At higher rubidium contents in compounds obtained by mechanical mixing, the superionic transition temperature raised insignificantly, the high-temperature phase conductivity decreased twofold, the low-temperature conductivity increased within the limits of the order of magnitude, and the system of hydrogen bonds was slightly weakened. In Cs1-xRbxH2PO4 crystals grown from solutions, the temperature of the superionic transition decreased along with its slowing down, and the low-temperature conductivity increased by more than three orders of magnitude because of the higher contents of residual acid aqueous centers in the structure of the salt. These systems are characterized by increased thermal stability.

VIBRATIONAL SPECTRA OF WO3·nH2O AND WO3 POLYMORPHS

G.N. Kustova, Yu.A. Chesalov, L.M. Plyasova, I.Yu. Molina, A.I. Nizovskii

Vib. Spectrosc., 55(2) (2011) pp. 235-240.

Vibrational spectra of polycrystalline WO3 hydrates and polymorphs were measured and analyzed. The effect of sampling techniques on IR spectra has been demonstrated. The phase transition into triclinic polymorph (C52h → C1i) has been revealed for the sample of monoclinic WO3 prepared as KBr pellet. Using the deuteration method in situ has shown that cubic WO3 is non-stoichiometric oxide stabilized by residual OH groups of WO3·H2O precursor.

 

INELASTIC ELECTRON SCATTERING IN THE ADSORBED SYSTEM

A.R. Cholach, N.N. Bulgakov, V.M. Tapilin

J. Struct. Chem., 52(suppl.) (2011) pp. S13-S20.

The study revealed additional channels of inelastic electron scattering, which accompany the threshold excitation of the substrate Pt4d level — ionization of the valent states of adsorbed particles chemically bonded to the excited atom, and excitation of the surface plasmon vibrations. The conjugate excitation of this type shows up as a series of typical satellites in the spectra of disappearance potentials, which reflects the structure of valent states of adsorbed particles. Analysis of the satellite structure revealed the intermediate formation of NHx,ads particles in the reaction NOgas + Hads on the surface of Pt(100) single crystal and, taking into account the earlier data, made it possible to formulate a general mechanism of selfoscillations in the NO + H2 reaction on platinum metals. Mathematical modeling of reaction kinetics on the Pt(100) surface within the suggested mechanism demonstrated the presence of regular self-oscillations of the reaction rate at invariable values of the step constants.

ADVANCED POWER OF DISAPPEARANCE POTENTIAL SPECTROSCOPY IN THE ADSORBED SPECIES IDENTIFICATION

A.R. Cholach

In “Chemical Physics Research Developments”, Ed. P.W. Hansen, Nova Press, 2011, ch. 6,

pp. 149-173.

The novel potentialities of Disappearance Potential Spectroscopy for fundamental studies and practical application are highlighted. Electronic structure of the adsorbed species can be characterized properly from an extended spectra processing due to following reasons. First, because of the pronounced sensitivity of this technique to precious few top sample layers exactly those are responsible for the processes of adsorption and surface reactions. Second, due to availability of the novel kind of electron-solid interaction, namely the conjugate electron excitation developed recently from the model studies. The latter phenomenon consists in ordinary substrate core level excitation accompanied by electron transition from the valence state of adsorbed particle to vacuum level. This is displayed experimentally as a set of spectral satellites localized by the respective ionization potential above the Fermi level of a given substrate component. It enables to fingerprint the electronic valence state structure and thus to ascertain the chemical nature of adsorbed species of any complexity. It also gives potentiality to determine an exact location of adsorbed particle on the composite substrate surface.

STATUS OF AEROGEL PRODUCTION IN NOVOSIBIRSK

A.Yu. Barnyakov*, M.Yu. Barnyakov*, K.I. Beloborodov*, V.S. Bobrovnikov*, A.R. Buzykaev*, V.B. Golubev*, B.V. Gulevich*, A.F. Danilyuk, S.A. Kononov*, E.A. Kravchenko*, K.A. Martin*, A.P. Onuchin*, V.V. Porosev*, S.I. Serednyakov* (*Budker Institute of Nuclear Physics, Novosibirsk, Russia)

Nucl. Instrum. Methods Phys. Res., Sect. A, 639(1) (2011) pp. 225-226.

Silica aerogel blocks are being produced for use in Cherenkov detectors by a collaboration of Boreskov Institute of Catalysis and Budker Institute of Nuclear Physics since 1986. Novosibirsk aerogel is used in several detectors; among them are KEDR, SND (BINP, Novosibirsk), LHCb (CERN, Geneva), AMS (for International Space Station mission) and others. Currently the investigations are going on in two directions: multilayer aerogels for Focusing Aerogel RICH and aerogels with high index of refraction. The authors have synthesized two-, three- and four-layer aerogel tiles with dimensions of 115 mm x 115 mm. The authors have modernized the method of pinhole drying for preparation of aerogels with refractive index in the range of 1.07-1.20.

FOCUSING AEROGEL RICH FOR PARTICLE IDENTIFICATION AND MOMENTUM MEASUREMENT

A.Yu. Barnyakov*, M.Yu. Barnyakov*, I.Yu. Basok*, V.E. Blinov*, V.S. Bobrovnikov*, A.A. Borodenko*, A.R. Buzykaev*, V.V. Gulevich*, A.F. Danilyuk, S.A. Kononov*, E.A. Kravchenko*, I.A. Kuyanov*, A.P. Onuchin*, I.V. Ovtin* (*Budker Institute of Nuclear Physics, Novosibirsk, Russia)

Nucl. Instrum. Methods Phys. Res., Sect. A, 639(1) (2011) pp. 290-293.

The work is devoted to the development of the Focusing Aerogel RICH (FARICH). The option of the forward RICH for the SuperB project in Italy is presented. It features an aerogel-NaF radiator and MCP photodetectors. Monte Carlo simulation predicts the π/K separation at the level better than 3σ from 0.2 to 7 GeV/c, the μ/π separation — from 0.13 to 1.3 GeV/c, and the kaon momentum measurement with an accuracy of about 1% at 1 GeV/c. FARICH for the Super Charm-Tau Factory project in Novosibirsk is proposed. Monte Carlo simulation predicts μ/π separation at the level better than 3σ for a momentum from 0.3 to 1.7 GeV/c. A prototype will be tested on the new electron test beam facility at VEPP-4M collider.

STRUCTURE MODIFICATION OF DIFFERENT GRAPHITE AND GLASSY CARBON SURFACES UNDER HIGH POWER ACTION BY HYDROGEN PLASMA

A.A. Shoshin*, A.V. Arzhannikov*, A.V. Burdakov*, K.N. Kuklin*, I.A. Ivanov*, K.I. Mekler*, S.V. Polosatkin*, V.V. Postupaev*, K.S. Raspopin, A.F. Rovenskikh*, P.A. Simonov, S.L. Sinitsky*, V.N. Snytnikov (*Budker Institute of Nuclear Physics, Novosibirsk, Russia)

Fusion Sci. Technol., 59(1T) (2011) pp. 268-270.

The studies of exposing of targets by hot-electron plasma exhaust from the multi-mirror trap GOL-3 are carried out. The results of Raman and SEM studies of surface modification of carbon materials with different ordering range of sp2 fraction (different graphite and glassy carbon) exposed by pulsed hot hydrogen plasma with energy density up to 8 MJ/m2 are presented. It is shown that on the depth up to ~80 nm due to this exposing there are obtained two effects – micro structural destruction of the surface and extension of crystallite size of sp2 phase, i.e. ordering of nanostructure.

DIAGNOSIS OF FUNCTIONAL MATERIALS

V.V. Malakhov

Fact. Lab. Mat. Diagnosis, 77(2) (2011) pp. 3-10.

Theoretical and experimental aspects of using chemical analytical methods in diagnostics of functional materials are considered. Currently, these methods are used to determine the gross elemental composition of materials, though the needs of diagnosis are mainly reduced to the necessity of determining the chemical composition of various manifestations of the fine structure of such objects. Presented are novel approaches associated with chemical stoichiographic methods. These methods do not need the reference samples of phases to be determined, thus providing simultaneous detection of both known and previously unknown phases, identification of phases by the stoichiometry of elemental composition and to quantitative determination of their content. The objects of analysis are dispersed powders, ceramics, crystals, thin films, hetero- and nano-structures. Examples of the using the stoichiographic methods in diagnostics of various functional materials are given.

METHODOLOGY AND PROCEDURE OF THE STOICHIOGRAPHIC ANALYSIS OF SOLID INORGANIC SUBSTANCES AND MATERIALS

V.V. Malakhov, N.N. Boldyreva, A.A. Vlasov, L.S. Dovlitova

J. Anal. Chem., 66(5) (2011) pp. 458-464.

The technical and experimental aspects of creating the conditions of differential dissolution in a flow stoichiographic system are discussed; the scheme of the experimental apparatus, stoichiograph, is presented. The construction, operation conditions of the main units of the stoichiograph, and sample treatment issues are considered. The principles of the creation and optimization of the conditions of the dynamic differential dissolution for the analysis of compounds and materials of the known and unknown phase composition are discussed: the composition of solvents and temperature, and the principles of their variation in time, including those in the processes of stoichiographic titration.

CALCULATIONS AND INTERPRETATION OF THE RESULTS OF STOICHIOGRAPHIC ANALYSIS OF SOLID MULTI-ELEMENT MULTI-PHASE COMPOUNDS AND MATERIALS

V.V. Malakhov, A.A. Vlasov

J. Anal. Chem., 66(3) (2011) pp. 262-268.

Methods and approaches to the calculations and interpretation of the results of stoichiographic analysis of solid multi-element multi-phase compounds and materials using the flow mode of the differential dissolution (DD) method are reported. Special features of calculationls as well as the objective reasons for the necessity of obtaining more or less precise results of stoichiographic calculations are discussed. The details of the procedure of stoichiographic calculations, refinement, and interpretation of the results are considered on an example of the DD-analysis of the Co-Ni-Fe-Bi-K-P-Mo-O/SiO2-catalyst for the selective oxidation and oxidative ammonolysis of hydrocarbons. The specific details and methods used for the estimation of the performance characteristics of the DD analytical procedure are discussed.

DETERMINATION OF THE CHEMICAL COMPOSITION OF SUPPORTED VANADIUM-CONTAINING OXIDE CATALYSTS BY THE DIFFERENTIAL DISSOLUTION METHOD

L.S. Dovlitova, A.A. Pochtar’, N.N. Boldyreva, V.V. Malakhov

J. Anal. Chem., 66(1) (2011) pp. 88-93.

The results of the application of the stoichiographic method of differential dissolution (DD) in the determination of the chemical composition of vanadium-containing catalysts are presented. In the studied catalyst series, amounts of vanadium were deposited onto TiO2, SiO2, Al2O3, ZrO2, and Nb2O5. The catalysts were prepared by the impregnation method or by the spray drying method and thermally treated at different temperatures. The DD method was used for the precise correction of the phase composition of the V2O5/TiO2 catalyst samples in order to determine the nature of the active component of these catalysts and obtain the correct information on their structure using the NMR method.

DETERMINATION OF THE CHEMICAL COMPOSITION OF FIBERGLASS SILICATE MATERIALS BY THE DIFFERENTIAL DISSOLUTION METHOD

L.S. Dovlitova, A.A. Pochtar’, N.N. Boldyreva, V.V. Malakhov

J. Anal. Chem., 66(10) (2011) pp. 981-990.

The standardless method of differential dissolution (DD) was used for determining the chemical composition of aluminosilicate and zirconium silicate glass-fiber clothes at different stages of their preparation and modification. Conditions for the detection, identification, and quantitative determination of various forms of heterogeneity in the elemental, phase, and surface compositions of these materials are considered. The distribution of the elements that constitute the glass-fiber clothes between various forms — surface ion-exchange (Na), hydrated (Al, Si), and framework (Al, Si) species — was quantitatively determined for the first time.

CHROMATOGRAPHIC AND ADSORPTION PROPERTIES OF THE MIXED STATIONARY PHASE POLY(1-TRIMETHYLSILYL-1-PROPYNE)/POLY(1-PHENYL-1-PROPYNE)

E.Yu. Yakovleva, V.Yu. Belotserkovskaya

J. Anal. Chem., 66(6) (2011) pp. 629-633.

Adsorption and chromatographic properties of the mixed stationary phase poly-(1-trimethylsilyl-1- propyne)/poly(1-phenyl-1-propyne) (PTMSP/PPP) composed as 97 : 3 by weight have been investigated by methods of low-temperature nitrogen adsorption and gas chromatography on packed columns. The resultant phase has uniform mesoporous structure. The chromatographic properties of the mixed phase are significantly different from the properties of the original porous polymers PTMSP and PPP. The adsorbent obtained by modifying

Chromosorb P NAW with a mixture of polymers provides the selective separation of chlorosubstituted, saturated, and aromatic hydrocarbons.

CHROMATOGRAPHIC PROPERTIES OF POLY(1-TRIMETHYLSILYL-1-PROPYNE)

V.Yu. Belotserkovskaya, E.Yu. Yakovleva

Russ. J. Phys. Chem. A, 85(5) (2011) pp. 851-856.

Changes in the properties of the surface of poly(1-trimethylsilyl-1-propyne) (PTMSP) over time were studied by gas chromatography combined with adsorption under static conditions. It was ascertained that a reduction in the volume of micropores in a polymer results in the sorption-desorption processes occurring preferentially in mesopores. The formation of a more chemically uniform surface leads to a considerable increase in the symmetry of chromatographic peaks and the efficiency of a column. These changes allow to broaden the range of compounds analyzed on columns with PTMSP.

DIHYDROGEN ADSORPTION ISOTHERMS (77 K) ON CARBON NANOMATERIALS

V.Yu. Gavrilov, E.A. Ustinov* (*Ioffe Physicotechnical Institute, St. Petersburg, Russia)

Kinet. Catal., 52(3) (2011) pp. 459-466.

Dihydrogen adsorption at 77 K on a number of fine-particle carbon materials, activated carbons, and carbon nanotubes has been investigated. The micropore structure parameters of these materials have been determined using a volumetric comparative method and nonlocal density functional theory (NLDFT). These data processing methods lead to different values of textural parameters. This difference is attributed to the presence of specific sorption sites on the surface of real carbon materials. The pore size range in which the NLDFT method is applicable to the C-H2 system has been determined. A comparison between the hydrogen sorption properties of different carbon nanotubes is presented.

Fundamental and Practical Approaches to Catalyst Preparation

SCIENTIFIC BASES OF CATALYST PREPARATION: INTRODUCTION INTO THEORY AND PRACTICE

N.A. Pakhomov

Eds. V.A. Sadykov, Novosibirsk, Publishing House SB RAS, 2011, 262 pp.

The monograph focuses on problems and aims of the catalyst preparation. The role of catalyst supports and requirements to them are discussed. Requirements to materials used for the catalyst preparation are formulated. Basic methods for granulation of catalyst masses are considered. Under discussion are physicochemical aspects of catalyst preparation by traditional methods of precipitation, supporting and mechanical mixing, as well as by new nanotechnology-based methods. Physicochemical basis of the sol-gel method are considered. Fundamentals of the classical theory of crystallization of insoluble hydroxides by the mechanism of oriented growing are given. Hydroxide interaction levels at co-precipitation are classified. Methods and mechanisms of immobilization of active components on the support surface in one- and multicomponent catalysts are considered. Processes observed at catalyst thermal treatment are considered: thermal destruction, sintering, polymorphous transformations, solid-phase reactions. Factors affecting the depth of component interaction in the catalysts prepared by mixing are shown. The monograph will be useful to under- and post-graduate students, researchers engaged in development and preparation of porous solid catalysts.

POROUS CERAMIC MATRIX Al2O3/Al COMPOSITES AS SUPPORTS AND PRECURSORS FOR CATALYSTS AND PERMEABLE MATERIALS

S.F. Tikhov, N.A. Pakhomov, E.I. Nemykina, A.N. Salanov, V.A. Sadykov, V.E. Romanenkov*, T.E. Pietiushyk* (*Powder Metallurgy Institute, Minsk, Belarus)

In “Metal, Ceramic and Polymeric Composites for Various Uses”, Ed. J. Cuppoletti, INTECH, Croatia, 2011, pp. 195-210.

Hydrothermal treatment of blends with aluminum metal powders provides an efficient technique for preparation of mechanically strong monolith composite materials with developed nanopore structure along with a relatively high fraction of macropores. The developed macropore structure provides a high permeability and decreases diffusion limitations inside the porous composite. Changing the reactivity of Al powder particles allows to tune the oxide/aluminum ratio, while their shape affect the monolith permeability. These materials can be used as filters or membrane supports.

Incorporation of precursors of the nanoporous materials in a macroporous system leads to a substantial increase of the nanopore volume. Application of granulated Al2O3/Al composites prepared from powdered blends of aluminum and thermally activated gibbsite as catalysts supports allowed to prepare catalysts with high activity and selectivity in dehydrogenation of isobutane.

MESOPOROUS ALUMINA IN AN Al2O3/Al CERMET PREPARED FROM POWDERED ALUMINUM

S.F. Tikhov, D.F. Khabibulin, O.B. Lapina, A.N. Salanov, Yu.N. Bespalko, V.A. Sadykov, A.I. Ratko*, T.F. Kouznetsova*, V.E. Romanenkov*, S.I. Eremenko* (*Institute of General and Inorganic Chemistry, Minsk, Belarus; **Powder Metallurgy Institute, Minsk, Belarus)

J. Mat. Sci. Eng., 5 (2011) pp. 281-292.

The synthesis of the mesoporous alumina by hydrothermal oxidation of powdered aluminum with an aqueous solution of polyethylene glycole (PEG) followed by calcination was studied. The increase of the PEG concentration from 0 to 3% was found to result in an increase of the alumina BET surface area from 254 to 406 m2/g, with the pore volume growing from 0.46 to 0.82 cm3/g and pore diameter increasing from 4.5 to 6.2 nm. The methods for regulating the mesopore structure in the Al2O3/Al cermet monoliths with the crushing strength 8.6-12.3 MPa the enhanced fraction of macropores (up to ~88 vol.%) were developed. The alumina structure in the cermets was characterized by 27Al MAS NMR. It was shown that aluminum oxide became more distorted in the cermets prepared with PEG and its distortion increased with the PEG concentration.

HYDROTHERMAL SYNTHESIS OF METAL OXIDE NANO- AND MICROPARTICLES IN SUPERCRITICAL WATER

V.I. Anikeev

Russ. J. Phys. Chem. A, 85(3) (2011) pp. 377-382.

Hydrothermal syntheses of nano- and microparticles of metal oxides of two types, LiMOn (LiCoO2, LiNiO2, LiZnO2, and LiCuO2) and MOn (Ga2O3, CeO2) were performed under continuous conditions in a tubular reactor with the use of supercritical water. An important role in the synthesis of nanoparticles and the reproducibility of the results was played by the conditions of mixing of supercritical water and precursor solution flows. The morphology and composition of synthesized compounds were studied by scanning electron microscopy and X-ray diffraction. The syntheses of LiCoO2, LiNiO2, LiZnO2, LiCuO2, Ga2O3, and CeO2 were most successful.

EFFECT OF CALCINATION TEMPERATURE ON THE PHYSICOCHEMICAL AND CATALYTIC PROPERTIES OF FeSO4/SiO2 IN HYDROGEN SULFIDE OXIDATION

M.A. Shuvaeva, I.V. Deliy, O.N. Martyanov, O.A. Bayukov*, E.I. Osetrov**, A.A. Saraev, V.V. Kaichev, N.S. Sakaeva***, G.A. Bukhtiyarova (*Kirenskii Institute of Physics, Krasnoyarsk, Russia; **Siberian Federal University, Krasnoyarsk, Russia; ***OAO Katalizator, Novosibirsk, Russia)

Kinet. Catal., 52(6) (2011) pp. 896-906.

The effect of calcination temperature on the state of the active component of iron-containing catalysts prepared by the impregnation of silica gel with a solution of FeSO4 and on their catalytic properties in selective H2S oxidation to sulfur was studied. With the use of thermal analysis, XPS, and Mössbauer spectroscopy, it was found that an X-ray amorphous iron-containing compound of complex composition was formed on the catalyst surface after thermal treatment in the temperature range of 400–500°C. This compound contained Fe3+ cations in three nonequivalent positions characteristic of various oxy and hydroxy sulfates and oxide and sulfate groups as anions. Calcination at 600°C led to the almost complete removal of sulfate groups; as a result, the formation of an oxide structure came into play, and it was completed by the production of finely dispersed iron oxide in the ε-Fe2O3 modification (the average particle size of 3.2 nm) after treatment at 900°C. As the calcination temperature was increased from 500 to 700°C, an increase in the catalyst activity in hydrogen sulfide selective oxidation was observed because of a change in the state of the active component. A comparative study of the samples by temperature-programmed sulfidation made it possible to establish that an increase in the calcination temperature leads to an increase in the stability of the iron-containing catalysts to the action of a reaction atmosphere.

 

INFLUENCE OF HEAT TREATMENT CONDITIONS ON THE PHYSICOCHEMICAL AND CATALYTIC PROPERTIES OF A CHROMIUM-CONTAINING CATALYST FOR TETRACHLOROETHYLENE HYDROFLUORINATION TO PENTAFLUOROETHANE

L.G. Simonova, A.A. Zirka, S.I. Reshetnikov, T.V. Larina, G.S. Litvak, L.G. Pinaeva, L.A. Isupova

Kinet. Catal., 52(3) (2011) pp. 418-426.

The physicochemical properties of coprecipitated 95% Cr2O3-5% Al2O3 oxide systems obtained by heat treatment of the precursor in nitrogen and air between 110 and 600°C and their influence on the catalytic activity in tetrachloroethylene hydrofluorination were studied by thermal and X-ray diffraction analyses, diffuse reflectance spectroscopy, and specific surface area measurements. The CrO1.9 compounds are more active than CrO1.5, but their preparation in the finely divided state is difficult because of the high exothermicity of the oxidation stage, which results in the decomposition of the oxides CrO1.9 and CrO1.5 followed by the crystallization and sintering of the decomposition products. Fine-powder and highly active chromium-containing oxides with CrO1.9 stoichiometry can be obtained by two-stage heating of hydroxides first in nitrogen and then in air at comparatively low temperatures.

CATALYTIC COMBUSTION OF METHANE ON SUBSTITUTED STRONTIUM FERRITES

M.V. Bukhtiyarova, A.S. Ivanova, E.M. Slavinskaya, L.M. Plyasova, V.A. Rogov, V.V. Kaichev, A.S. Noskov

Fuel, 90(3) (2011) pp. 1245-1256.

Sr–hexaferrites prepared by co-precipitation method and calcined at 700–1000°С have been characterized by thermogravimetric and differential thermal analysis (TG–DTA), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), and Ar adsorption techniques. It has been shown that hexaferrite phase formed after calcination at 700°С is amorphous and its crystallization occurs at 800°С. Specific surface area (SBET) of the samples calcined at 700°С is 30–60 m2/g. Reduction in hydrogen proceeds in several steps, Fe(III) in the hexaferrite structure being practically reduced to Fe0. Amount of hydrogen necessary for the reduction of the samples decrease in the order: SrMn2Fe10O19 > SrFe12O19 > SrMn6Fe6O19 > SrMn2Al10O19. Surface composition of the ferrites differs from bulk. According to XPS data, the surface is enriched with strontium. Sr segregation is most probably explained by the formation of surface carbonates and hydroxocarbonates. The main components on the surface are in oxidized states: Mn3+ and Fe3+. Maximum activity in the methane oxidation is achieved for the SrMnxFe12-xO19 (0 < x < 2) catalysts. These samples are characterized by highest amount of the hexaferrite phase, which promotes change of oxidation state Mn(Fe)3+ <-> Mn(Fe)2+.

CATALYSTS FOR PROCESSING LIGHT HYDROCARBON RAW STOCK: COMBUSTION SYNTHESIS AND CHARACTERIZATION

G.B. Aldashukurova*, N.V. Shikina, A.V. Mironenko*, Z.A. Mansurov*, Z.R. Ismagilov (*Al-Farabi National University, Almaty, Kazakhstan)

Int. J. Self-Propag. High-Temp. Synth., 20(2) (2011) pp. 124-127.

Fiber glass supported nanosized Co and Co-Ni catalysts were prepared by solution-combustion synthesis and characterized for their structure and catalytic activity.

PREPARATION AND CHARACTERIZATION OF BULK URANIUM OXIDES FOR CATALYSIS

Z.R. Ismagilov, S.V. Lazareva, N.V. Shikina, V.V. Kuznetsov, M.A. Kerzhentsev,

Yu.V. Ostrovskii*, N.A. Rudina, V.A. Rogov, V.A. Ushakov (*Novosibirsk Branch of JSC “State Specialized Design Institute” Novosibirsky “VNIPIET”)

Mendeleev Commun., 21(4) (2011) pp. 209-211.

The physicochemical and catalytic properties of bulk uranium oxides prepared by the thermal decomposition of uranyl nitrate [UO2(NO3)2·6H2O] and precipitation from an aqueous solution of this salt are reported.

PREPARATION OF CuO-CeO2 CATALYSTS DEPOSITED ON GLASS CLOTH BY SURFACE SELF-PROPAGATING THERMAL SYNTHESIS

I.V. Desyatykh, A.A. Vedyagin, Yu.S. Kotolevich*, P.G. Tsyrulnikov* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Combust. Explosion Shock Waves, 47(6) (2011) pp. 677-682.

(CuO-CeO2)/glass cloth acting as CO oxidation catalyst was prepared by surface selfpropagating thermal synthesis. In the process of synthesis of (CuO-CeO2)/glass cloth samples, the content of active components (CuO-CeO2) and fuel additives and the conditions of thermal synthesis were varied. Impact of the nature of fuel additives and salts that are precursors of active components, and their ratio on the reaction of solid-phase combustion were studied. The resulting catalysts were studied with the use of scanning electron microscopy and in situ time-resolved synchrotron radiation powder X-ray diffraction.

BIFUNCTIONAL CATALYSTS OF HYDROGENATION PROCESSES

O.V. Klimov

Chem. Sustain. Devel., 19(1) (2011) pp. 59-60.

A new approach to the preparation of highly active bifunctional catalysts of hydrogenation processes providing an increase in the extent of oil processing and obtaining motor fuel in agreement with the world standards is proposed. This approach is based on the preparation of the support containing acidic components, and on purposive selective synthesis of the active component of hydrogenolysis and hydrogenation - Co(Ni)-Mo(W)-S-phase. The latter is localized in the catalyst in such a manner that it is available for all the raw material components to be transformed catalytically. The preparation procedure is based on the solution synthesis of bimetal compounds that are precursors of the active component. Within the framework of the proposed approach, highly active catalysts intended for hydrocracking and hydropurification of various oil distillates can be obtained.

SYNTHESIS OF TITANIUM OXIDE STRUCTURES ON MESOPOROUS SILICON DIOXIDE SURFACE BY MOLECULAR LAYERING

Yu.M. Koshtyal*, A.A. Malkov*, A.A. Malygin*, A.N. Shmakov, M.S. Melgunov (*St. Petersburg State Institute of Technology, St. Petersburg, Russia)

Colloid J., 73(4) (2011) pp. 495-503.

The formation of titanium oxide structures through the repeated successive treatment of SBA-15 mesoporous silicon dioxide with vapors of TiCl4 and H2O at 200°C is investigated. The influence of the number of synthesis cycles on the character of the buildup of the surface titanium oxide structures and changes in the adsorption and structural characteristics of modified silica is shown.

MODIFYING THE FUNCTIONAL COVER OF THE γ-Al2O3 SURFACE USING ORGANIC SALTS OF ALUMINUM

R.M. Mironenko*, O.B. Belskaya*, I.G. Danilova, V.P. Talzi*, V.A. Likholobov* (*Institute of Hydrocarbons Processing, Omsk, Russia)

Kinet. Catal., 52(4) (2011) pp. 629-636.

A method is suggested for modifying the surface properties of alumina without changing its chemical composition. The sorption of aluminum complexes with organic acid ligands on the γ-Al2O3 surface is reported. The thermal decomposition of the adsorbed oxalate complexes yields supported aluminum oxide compounds on the surface of the initial support. This modifies the functional cover of the γ-Al2O3 surface, altering the proportions of different types of surface hydroxyl groups, reducing their total number, and lowering the concentration of weak Lewis acid sites.

PREPARATION OF Ag/HOPG MODEL CATALYSTS WITH A VARIABLE PARTICLE SIZE AND AN in situ XPS STUDY OF THEIR CATALYTIC PROPERTIES IN ETHYLENE OXIDATION

D.V. Demidov, I.P. Prosvirin, A.M. Sorokin, T. Rocha*, A. Knop-Gericke*, V.I. Bukhtiyarov (*Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany)

Kinet. Catal., 52(6) (2011) pp. 855-861.

The preparation of model silver catalysts supported on highly oriented pyrolytic graphite is described, and the effect of the Ag particle size on the catalytic ethylene

oxidation into ethylene oxide, studied by in situ XPS and mass spectrometry, is considered. For a mean particle diameter of 8 nm, the adsorbed oxygen species characterized by an O 1s binding energy of 530.8 ± 0.2 eV (electrophilic oxygen) forms on the silver surface exposed to the ethylene–oxygen reaction mixture. Larger silver particles with a mean diameter of 40 nm additionally contain the adsorbed oxygen species characterized by an O 1s binding energy of 529.2± 0.2 eV (nucleophilic oxygen). The presence of both oxygen species on the surface of the larger particles ensures the formation of ethylene oxide, while the sample with the smaller silver particles is inactive in the epoxidation reaction. The O 1s signal at 530.8 eV is partly due to oxygen dissolved in the subsurface layers of silver.

MODEL Ag/HOPG CATALYSTS: PREPARATION AND STM/XPS STUDY

D.V. Demidov, I.P. Prosvirin, A.M. Sorokin, V.I. Bukhtiyarov

Catal. Sci. Technol., 8 (2011) pp. 1432-1439.

Model catalysts - Ag on highly oriented pyrolytic graphite (Ag/HOPG) - have been studied using scanning tunneling microscopy (STM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES). Two types of catalysts were compared: Ag nanoparticles supported on sputtered and non-sputtered HOPG, and the influence of graphite surface defects on the stabilization of Ag nano-sized particles was discussed. A procedure for the preparation of stable (up to 250°C under a submillibar oxygen/ethylene pressure) silver nanoparticles is suggested. The disappearance of Ag particles in STM images after a sample treatment in the ambient conditions is explained in terms of silver penetration into graphite and the loss of conductivity due to adsorption of contaminants.

TEMPLATE SYNTHESIS OF 3-D STRUCTURED MACROPOROUS OXIDES

E.V. Parkhomchuk, K.A. Sashkina, N.A. Rudina, A.G. Okunev, V.N. Parmon

Alternative Energy Ecol., 102(10) (2011) pp. 35-39.

The work is devoted to the producing of 3-D macroporous structure of inorganic oxides by template method. According to the literature, catalysts based on

the macroporous oxides possess improved transport properties with respect to high molecular weight reagents in the most industrially important chemical processes. In this work templates for producing of 3-D macroporous structure of inorganic oxides are obtained, they consist of close packed monodispersed polystyrene spheres. The spheres size is controlled by conditions of emulsion styrene polymerization, namely is strongly depends on polymerization temperature. With the use of templates macroporous alumina, zirconia, amorphous silica and silicalite-1 are obtained. It is shown that template synthesis results in significant increase of pore volume and external area of porous oxide.

CONTROL OF METAL DISPERSION, CHEMICAL COMPOSITION AND TEXTURE OF PALLADIUM-ZINC CATALYSTS ON MESOPOROUS TITANIA

L.B. Okhlopkova, M.A. Kerzhentsev, Z.R. Ismagilov

IRECHE, 3(6) (2011) pp. 774-783.

Nanoparticle-doped mesoporous titania coatings were synthesized by incorporation of PdZn nanoparticles into support sol and deposition of the resulting sol on the inner surface of a fused silica capillary. This method allows controlling the chemical nature of the film, the porosity, metal dispersion and loading with an active species. The structural properties, chemical composition and morphology of the active component and the support were studied by means of TEM, EDS, ICP AES, X-ray diffraction and N2 adsorption. Monodispersed PdZn bimetallic colloidal particles were prepared by polyol method in the presence of polyvinylpyrrolidone. The average particle size ranging from 1.8-4.3 nm was found to depend on the amount of PVP added and NaOH concentration. The bulk composition of nanoparticles depends on concentrations of the precursors and NaOH. The reaction mechanism is shown to involve the oxidation of ethylene glycol to mainly glyoxal and glycolic acid, while the metal Pd salts are reduced to form catalysts for Zn2+ ions reduction. Palladium-zinc-incorporated mesoporous TiO2 films were synthesized by a sol-gel method using a nonionic structure-directing agent Pluronic F127. The control of the pore size of the mesoporous titania was achieved by adding co-surfactants, such as n-butanol. The influence of the activation conditions on crystallite size and composition of metal particles was investigated.

PLATINUM CATALYSTS ON ACTIVATED CARBON SUPPORTS PREPARED FROM MONONUCLEAR AND POLYNUCLEAR PRECURSORS. INFLUENCE OF POROUS STRUCTURE OF THE SUPPORT

L.B. Okhlopkova, S.Yu. Troitskii

In “Activated Carbon: Classifications, Properties and Applications”, Nova Science Publishers, 2011,pp. 393-408.

A number of catalysts have been prepared by adsorption of platinum precursors on activated carbons of different origin followed by reduction in flowing hydrogen. They were characterized by CO chemisorption, TEM and liquid-phase hydrogenation of cyclohexene. Porous structure of the support and the nature of platinum precursor proved to have a profound influence on the properties of catalysts. The metal dispersion of catalysts prepared from platinum (IV) chloride can be controlled in the range from 10 to 90%. Activity of the catalysts reached a maximum in the range of intermediate metal dispersion, with the limit being dependent on the support used. It has been suggested that a part of the supported metal became inaccessible to the organic substrate due to localization of metal particles in narrow pores of the support. The extent of blocking proved to be higher for highly dispersed Pt particles and on the supports with smaller pores. An alternative route to preparing supported Pt catalysts is the synthesis of polynuclear hydroxochloride complexes from Pt(II) chloride that is followed by their deposition on carbon. The catalysts prepared from polynuclear precursor showed high activity even in the range of high metal dispersion and for microporous carbons. Structure of product of Pt(II) chloride hydrolysis was established by means of NMR 195Pt, 17O.

SYNTHESIS OF NANOSIZE Co–Rh SYSTEMS AND STUDY OF THEIR PROPERTIES

A.I. Gubanov*, E.M. Churakova**, S.D. Badmaev, P.V. Snytnikov, E.Yu. Filatov*, P.E. Plyusnin*, N.V. Kurat’eva*, V.A. Sobyanin, S.V. Korneev* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Novosibirsk State University, Novosibirsk, Russia)

Russ. J. Appl. Chem., 84(10) (2011) pp. 1677-1683.

Precursor compounds [Co(NH3)6][Rh(NO2)6] and [Co(NH3)6][Co(NO2)6], solid solutions [Co(NH3)6] [Rh(NO2)6]1–x[Co(NO2)6]x, and solid solutions Na3[Rh1–xCox(NO2)6] were synthesized and studied by IR spectroscopy and elemental, X-ray phase, X-ray diffraction, and thermogravimetric analyses. X-ray phase analysis was employed to examine products of thermal decomposition of precursors in the atmospheres of hydrogen and helium. Catalysts with a Co–Rh active system, supported by ZrO2, were prepared and tested in the reaction of steam conversion of ethanol.

EFFECT OF YTTRIUM OXIDE ON THE FORMATION OF THE PHASE COMPOSITION AND POROUS STRUCTURE OF TITANIUM DIOXIDE

A.A. Shutilov, G.A. Zenkovets, V.Yu. Gavrilov, S.V. Tsybulya

Kinet. Catal., 52(1) (2011) pp. 111-118.

The formation of the structure of TiO2 (anatase) doped with 1–5 mol % Y2O3 is reported. The dopant changes the anatase structure from regular to nanocrystalline. The nanocrystalline structure consists of incoherently intergrown 5- to 7-nm anatase crystallites (500°C) separated by interblock boundaries accommodating yttrium ions. The formation of the nanocrystalline anatase structure stabilizes small anatase crystallites and raises the anatase-to-rutile phase transition temperature above 900°C. Owing to this structure, the developed specific surface area and fine porous texture of yttrium oxide-doped titanium dioxide survive up to higher temperatures than those of undoped titanium dioxide.

NANOCRYSTAL AEROGELS OF METAL OXIDES AS DESTRUCTIVE SORBENTS AND CATALYSTS

A.F. Bedilo, E.V. Ilyina, I.V. Mishakov, A.A. Vedyagin

Chem. Sustain. Devel., 19(1) (2011) pp. 31-38.

The procedure of the synthesis of aerogels Al2O3 and VOx/MgO with the particle size of several nanometers was developed. The specific surface of materials obtained after drying under supercritical conditions exceeded 1000 m/g. The possibility to govern the properties of aerogels through modification with acids and β-diketones of the solutions of alkoxides used as initial substances was revealed. The high activity of modified aerogel of Al2O3 in the processes of destructive sorption and catalytic dehydrohalogenation was demonstrated. It was shown that the aerogel VOx/MgO exhibits high activity in the reaction of decomposition of freon CF2Cl2.

SYNTHESIS OF PROPYLENE GLYCOL METHYL ETHER FROM METHANOL AND PROPYLENE OXIDE OVER ALUMINA-PILLARED CLAYS

M.N. Timofeeva, V.N. Panchenko, A. Gil*, Yu.A. Chesalov, T.P. Sorokina**, V.A. Likholobov** (*Universidad Publica de Navarra, Pamplona, Spain; **Institute of Hydrocarbons Processing, Omsk, Russia)

Appl. Catal., B, 102(3-4) (2011) pp. 433-440.

Al-pillared interlayered clays (Al-PILCs) have been synthesized by the exchange reaction between Na-clay and Al-hydroxypolycation solutions aged for 0.5–14 days and characterized by DRS-UV–vis, XRD, FT-IR and N2-adsorption/desorption analyses, Hammett acidity titration with n-butylamine and FT-IR spectroscopy using PhCN and CDCl3 as probe molecules. It was found that the aging time of Al-hydroxypolycation pillaring solution affects both the textural characteristics and the physicochemical properties of Al-PILCs. Al-PILCs have been tested as catalysts for synthesis of propylene glycol methyl ether from methanol and propylene oxide. Increase in Al content due to the prolonged aging time favors the increase in the activity of Al-PILCs.

EFFECT OF THE ACID–BASE PROPERTIES OF Zr,Al-PILLARED CLAYS ON THE CATALYTIC PERFORMANCES IN THE REACTION OF PROPYLENE OXIDE WITH METHANOL

M.N. Timofeeva, V.N. Panchenko, A. Gil*, V.P. Doronin**, A.V. Golovin, A.S. Andreev, V.A. Likholobov** (*Universidad Publica de Navarra, Pamplona, Spain; **Institute of Hydrocarbons Processing, Omsk, Russia)

Appl. Catal., B, 104(1-2) (2011) pp. 54-63.

A series of Zr,Al-pillared interlayered clays (Zr,Al-PILCs) have been prepared and characterized by X-ray diffraction, elemental analysis, FT-IR and N2-adsorption/desorption analyses, 27Al NMR(MAS), FT-IR spectroscopy using pyridine, PhCN and CDCl3 as probe molecules. It was found that textural and physicochemical properties of Zr,Al-PILCs depend on Zr content in clay. The relationship between the acid– base properties and catalytic performances of Zr,Al-PILCs was revealed in the synthesis of propylene glycol methyl ether from methanol and propylene oxide. The results show that the conversion of propylene oxide and the selectivity to 1-methoxy-2-propanol decrease with increasing the amount of zirconium in Zr,Al-PILCs due to the change in acid–base properties.

EFFECT OF THE NATURE OF THE ADDITIVES OF METAL CATIONS (Sr, Ba, AND La) ON THE PROPERTIES OF Co–Mo HYDRODESULFURIZATION CATALYSTS

E.V. Korneeva, A.S. Ivanova, G.A. Bukhtiyarova, P.V. Aleksandrov, V.I. Zaikovsky, I.P. Prosvirin, A.S. Noskov

Kinet. Catal., 52(4) (2011) pp. 579-594.

The effect of the nature of the support modified with the ions of alkaline earth and rare earth elements (Sr, Ba, and La) on the properties of Co–Mo catalysts for the hydrodesulfurization of dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was studied using a set of physicochemical and catalytic techniques. It was found that the introduction of modifying additives decreased the surface concentration of Lewis acid sites (LASs) and increased the concentration of basic sites (BSs) in aluminum-containing supports; these changes were more significant upon modification with lanthanum and strontium. The modification affected the distribution and degree of dispersion of Co–Mo–S sulfide packets. It was found that the rate constants of DBT and 4-MDBT conversion increased with decreasing total surface concentration of both LASs and BSs on the support. The highest rate constant of 4,6-DMDBT conversion was reached at an optimum concentration of weak Lewis sites on Co–Mo catalysts, whose support was modified with strontium or barium.

MICROWAVE IRRADIATION SYNTHESIS OF SAPO-31 MOLECULAR SIEVE AND ITS CHARACTERIZATION AND CATALYTIC PERFORMANCE

J. Yang*, W. Wu*, Ya. Zhou*, G. Wu*, A. Zhao*, O.V. Kikhtyanin, A.V. Toktarev, G.V. Echevsky (*Sino-Russian Joint Laboratory for Catalysis, Heilongjiang University, Harbin, Heilongjiang, China)

Chinese J. Catal., 32(7) (2011) pp. 1234-1241.

AlPO4-31 molecular sieve was synthesized by microwave irradiation using aluminum isopropoxide, orthophosphoric acid, and di-n-butylamine as sources of aluminum, phosphorus, and template, respectively. The crystallization conditions of AlPO4-31 were optimized. SAPO-31 molecular sieve samples with different silicon contents were synthesized at the optimal conditions. The structure and acidity of the samples were characterized by X-ray diffraction, N2 physical adsorption, scanning electron microscopy, 29Si MAS NMR, NH3 temperature-programmed desorption, FT-IR of adsorbed pyridine. The catalytic performance of Pd/SAPO-31 bifunctional catalyst for hydroisomerization of n-decane was investigated. The results indicated that the AlPO4-31 and SAPO-31 molecular sieves with pure crystal phase and higher crystallinity assigned to ATO topology structure were obtained at 170oC for 2 h by microwave irradiation. The BET surface area and micropore volume were increased because of the introduction of Si to the framework of AlPO4-31. The distribution of Si in the framework and the acidity of the SAPO-31 molecular sieve were varied by changing the composition of the reaction mixture. The bifunctional catalyst Pd/SAPO-31 with suitable acidity showed high activity and selectivity for hydroisomerization of n-decane.

FACILE SYNTHESIS OF NANOSIZED ε-Fe2O3 PARTICLES ON THE SILICA SUPPORT

G.A. Bukhtiyarova, M.A. Shuvaeva, O.A. Bayukov*, S.S. Yakushkin, O.N. Martyanov (*Kirensky Institute of Physics, Krasnoyarsk, Russia)

J. Nanopart. Res., 13(10) (2011) pp. 5527-5534.

An approach is suggested to synthesize the ε-Fe2O3 particles supported on silica with the mean size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs. The facile synthesis is based on the pore filling impregnation method by iron sulfate (II) water solution with the following annealing procedure at similar to 1173 K. It is shown that the ε-Fe2O3 nanoparticles obtained are stable up to similar to 1173 K and possess superparamagnetic behavior up to similar to 870 K.

AN INVERTED SPHERICAL MODEL OF AN OPEN-CELL FOAM STRUCTURE

O. Smorygo*, V.V. Mikutski*, A. Marukovich*, A. Ilyushchanka*, V.A. Sadykov, A. Smirnova** (*Powder Metallurgy Institute, Minsk, Belarus; **Eastern Connecticut State University, Storrs, USA)

Acta Mater., 59(7) (2011) pp. 2669-2678.

An inverted open-cell foam model based on hexagonal close packing symmetry is proposed for open-cell foams with different configuration of struts. The novel model predicts the properties of the broad spectrum of open-cell ceramic and metallic structures. According to the proposed model, the specific surface and hydraulic permeability can be derived from experimentally measurable parameters such as porosity and cell diameter. The calculated parameters are in good correlation with the experimental data even without introducing additional empirical coefficients.

GAS-PHASE EPOXIDATION OF BUTADIENE: INFLUENCE OF THE CONTENT AND DISTRIBUTION OF CESIUM PROMOTER ON CATALYTIC PROPERTIES Ag/α–Al2O3

D.S. Afanasiev, T.V. Larina, N.I. Kuznetsova

Catal. Ind., 4(2) (2011) pp. 89-95.

Using the well-known patent methods, the authors have synthesized 1,3-butadiene epoxidation α-Al2O3 supported catalysts containing 15 wt% of Ag and 250–1500 ppm of Cs (Johnson Matthey, H16P07). The physicochemical properties of samples are systematically studied by varying the dispersion of supported silver, the amount of an introduced promoter, and its distribution over the surface of a catalyst. Catalytic tests of samples show that the optimum amount of a promoter depends directly on the surface of a catalyst. With optimum promotion, the steady-state activity of catalysts is determined by the dispersion of supported silver. In the course of catalytic tests, it is established that the shape of kinetic curves is governed by the excess or lack of Cs in a catalyst, thus providing a method for optimizing the concentration of the promoter. An analysis of the energy dispersion spectra (EDS) is applied for the first time to study the distribution of Cs over the surface of promoted catalysts. It is shown that thermal treatment favors the uniform distribution of a promoter over the surface of a catalyst and shortens the time required toattain its steady-state activity in catalytic tests. In the work, the steady-state productivity of catalysts reaches 0.5 g of 3,4-epoxy-1-butene per gram of the catalyst per hour, thus exceeding the claimed patent values.

MIL-101 SUPPORTED POLYOXOMETALATES: SYNTHESIS, CHARACTERIZATION, AND CATALYTIC APPLICATIONS IN SELECTIVE LIQUID-PHASE OXIDATION

N.V. Maksimchuk, O.A. Kholdeeva, K.A. Kovalenko*, V.P. Fedin* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Israel J. Chem., 51(2) (2011) pp. 281-289.

Recent achievements in the preparation of heterogeneous catalysts via incorporation of polyoxometalates (POMs) within cages of the mesoporous coordination polymer MIL-101, their physicochemical characterization, and application for liquidphase selective oxidation of organic compounds with green oxidants — O2 and aqueous H2O2 are presented. Special attention is paid to analyze a manifestation of confinement effects and to address the issues of catalytic activity and selectivity after immobilization and after recycling, catalyst resistance to POM leaching, and the nature of catalysis. The scope and limitations of POM/MIL-101 catalysts are discussed.

 

IRON TETRASULFOPHTHALOCYANINE IMMOBILIZED ON METAL ORGANIC FRAMEWORK MIL-101: SYNTHESIS, CHARACTERIZATION AND CATALYTIC PROPERTIES

O.V. Zalomaeva, K.A. Kovalenko*, Yu.A. Chesalov, M.S. Melgunov, V.I. Zaikovsky, V.V. Kaichev, A.B. Sorokin**, O.A. Kholdeeva, V.P. Fedin* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Institut de Recherches sur la Catalyse et l’Environnement de Lyon, Villeurbanne Cedex, France)

Dalton Trans., 40 (2011) pp. 1441-1444.

Iron tetrasulfophthalocyanine (FePcS) has been irreversibly inserted into nanocages of the metal organic framework MIL-101 to give a hybrid material FePcS/MIL-101 which demonstrated a superior catalytic performance in the selective oxidation of aromatic substrates with tBuOOH than homogeneous FePcS.

EFFECT OF OXYGEN ADSORPTION ON THE SURFACE PLASMON RESONANCE OF OXIDE-SUPPORTED SILVER NANOPARTICLES

D.S. Afanasiev, V.F. Anufrienko, S.Ph. Ruzankin, T.V. Larina, N.I. Kuznetsova, V.I. Bukhtiyarov

Doklady Phys. Chem., 436(2) (2011) pp. 23–25.

In the present work, the surface plasmon resonance (SPR) of oxide-supported silver nanoparticles was studied. It was demonstrated that oxygen adsorption (formation of an oxide film) had an effect on the SPR position of fine silver nanoparticles.

Carbon and Carbon Related Materials

MODIFICATION OF NANOFIBROUS CARBON MORPHOLOGY UNDER EFFECT OF LASER ABLATION

G.G. Kuvshinov*, Yu.L. Krutskii*, I.S. Chukanov*, A.M. Orishich**, Yu.V. Afonin**, V.I. Zaikovsky, D.G. Kuvshinov** (*Novosibirsk State Technical University, Novosibirsk, Russia; **Institute of Theoretical and Applied Mechanics, Novosibirsk, Russia)

Nanotechn. Russia, 6(9-10) (2011) pp. 607-612.

This paper presents the results of studies of carbon nanostructures obtained by the laser ablation of a nanofibrous carbon formed in the process of a catalytic decomposition of hydrocarbons in the presence of high-percentage catalysts containing the iron subgroup of metals. A continuous CO2 laser with a radiation density of 3.4 W/cm2 was used in the experiments. The target was placed on a cooled copper substrate in a helium medium under a pressure of 770–780 torr. Upon the impact of laser radiation, the carbon evaporated and, further, condensed on the surface of a special condenser. The samples were collected from the condenser surface and the target in the radiation-exposed area. The products were studied by high resolution transmission electron microscopy using a JEM-2010 electron microscope. A number of samples underwent a local energy dispersion X-ray microanalysis on the EDAX spectrometer. Multilayer nanotubes of diameters 14–40 nm and lengths of up to 2 μm have been found in the evaporated and condensed carbon materials. It was established that part of the nanotubes was filled by the catalyst metal. Interestingly, in the target area exposed to the radiation, the initial material comprising carbon nanofibers with the structure of inserted cones transformed into carbon nanotubes (CNTs) with an average cross-section size of 20 nm.

PALLADIUM-CONTAINING MULTIWALL NANOTUBES AS CATALYSTS FOR HYDROGENATION

N.N. Osipov*, N.A. Magdalinova*, V.V. Chesnokov, A.S. Chichkan*, M.V. Klyuev* (*Ivanovo State University, Ivanovo, Russia ,Vestnik Ivanovskogo Gosudarstvennogo Universiteta,

2 (2011) pp. 61-63.

Palladium-containing multiwall carbon nanotubes were obtained and their catalytic activity was studied in model reaction of nitrobenzene hydrogenation. It was shown, that reaction rate is lower than for platinum analogues.

CATALYSTS BASED ON FILAMENTOUS CARBON IN THE HYDROGENATION OF AROMATIC COMPOUNDS

N.A. Zaitseva, V.V. Goidin, V.V. Molchanov, V.V. Chesnokov, R.A. Buyanov, V.A. Utkin

Kinet. Catal., 52(5) (2011) pp. 770-773.

In order to extend the area of application of the base catalytic system metal–filamentous carbon, the catalytic properties of Ni–filamentous carbon catalysts have been tested in the hydrogenation of aromatic compounds (benzene, benzyl cyanide, benzophenone, and nitrobenzene). The selectivity of the catalysts depends on the outer faceting of the active metal particles. The benzene ring is hydrogenated on the (111) face of the metal nanoparticles, whereas the selective hydrogenation of functional groups in substituted aromatic compounds occurs on the surface of active component nanoparticles in which the (111) face is blocked.

STRUCTURE AND ELECTROPHYSICAL PROPERTIES OF MULTIWALLED CARBON NANOTUBE/POLYMETHYLMETHACRYLATE COMPOSITES PREPARED VIA COAGULATION TECHNIQUE

I.N. Mazov, V.L. Kuznetsov, S.I. Moseenkov, A.V. Ishchenko, N.A. Rudina, A.I. Romanenko*, T.I. Buryakov*, O.B. Anikeeva*, J. Macutkevic**, D. Seliuta**, G. Valusis**, J. Banys*** (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Semiconductor Physics Institute, Vilnius, Lithuania; ***University of Vilnius, Vilnius, Lithuania)

Nanosci. Nanotechn. Lett., 3(1) (2011) pp. 18-23.

This paper considers the formation of the conductive network in the composite system of multiwall carbon nanotubes (MWNT) and polymethylmetacrylate (PMMA) produced via coagulation technique. All stages of formation of uniform composite materials with high state of MWNT dispersion were characterized with optical microscopy, TEM, SEM along with conductivity measurements. The key stage is the formation of precipitate of polymer on the surface of MWNTs suspended in suitable solvent which provides effective wetting of MWNT surface with polymer and formation of the “polymer-NT” interface. This precipitate (powder) was used to produce composite film, which electrophysical properties were characterized with four-probe electrical conductivity measurements and by broadband dielectric spectroscopy (20 Hz-1 MHz). Both static and low-frequency analysis demonstrate low percolation threshold (lower than 1 wt%) for the produced MWNT/polymethylmetacrylate composites, whereas a much higher MWNT concentration (3∼4 wt%) is needed to form a conductive network for the composite films produced by other methods, such as extrusion or solvent cast technique.

STRUCTURE AND PROPERTIES OF MULTIWALL CARBON NANOTUBES/POLYSTYRENE COMPOSITES PREPARED VIA COAGULATION PRECIPITATION TECHNIQUE

I.N. Mazov, V.L. Kuznetsov, D.V. Krasnikov, N.A. Rudina, A.I. Romanenko*, O.B. Anikeeva*, V.I. Suslyaev**, E.Yu. Korovin**, V.A. Zhuravlev** (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Nanotechn., ID 648324 (2011) 7 pp.

Coagulation technique was applied for preparation of multiwall carbon nanotube- (MWNT-containing polystyrene (PSt) composite materials with different MWNT loading (0.5–10 wt%). Scanning and transmission electron microscopies were used for investigation of the morphology and structure of produced composites. It was shown that synthesis of MWNT/PSt composites using coagulation technique allows one to obtain high dispersion degree of MWNT in the polymer matrix. According to microscopy data, composite powder consists of the polystyrene matrix forming spherical particles with diameter ca. 100–200 nm, and the surface of MWNT is strongly wetted by the polymer forming thin layer with 5–10 nm thickness.

Electrical conductivity of MWNT/PSt composites was investigated using a four-probe technique. Observed electrical percolation threshold of composite materials is near to 10 wt%, mainly due to the insulating polymer layer deposited on the surface of nanotubes. Electromagnetic response of prepared materials was investigated in broadband region (0.01–4 and 26–36 GHz). It was found that MWNT/PSt composites are almost radiotransparent for low frequency region and possess high absorbance of EM radiation at higher frequencies.

 

INFLUENCE OF THE DIELECTRIC MATRIX ON THE ELECTRICAL NANOCOMPOSITES BASED ON OXIDIZED MULTI-WALLED CARBON NANOTUBES

I.V. Totosov*, A.I. Romanenko*, O.B. Anikeeva*, V.L. Kuznetsov, I.N. Mazov, S.I. Popkov**, K.A. Shaichutdinov** (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Kirensky Institute of Physics, Krasnoyarsk, Russia)

J. Siberian Federal Univ. Math. & Phys., 4(2) (2011) pp. 175-181.

In this paper the authors consider the effect of oxidative treatments on the properties of multiwalled carbon nanotubes (MWNT). The experimental temperature dependence of electrical conductivity (in the temperature range 4,2–293 K) and field dependence of magnetoresistance (in fields up to 9 Tl at 10 K) of the samples with MWCNT modified by oxidation of the surface layers, as well as the composites based on them. It was established that the oxidation of the surface layers of MWCNTs in acid solutions leads to a change in the temperature dependence of electrical conductivity. Introduction of MWCNTs in a dielectric matrix of polymethylmethacrylate (PMMA) leads to the dependence of the conductivity close to that typical for hopping conductivity with variable hopping length, three-dimensional case.

TEMPERATURE DEPENDENCES OF CONDUCTIVITY AND

MAGNETOCONDUCTIVITY OF MULTIWALL CARBON NANOTUBES ANNEALED AT DIFFERENT TEMPERATURES

S.D. Borodanov*, A.I. Romanenko*, O.B. Anikeeva*, V.L. Kuznetsov, K.V. Elumeeva, S.I. Moseenkov (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Siberian Federal Univ. Math. & Phys., 4(2) (2011) pp. 143-148.

Temperature (in range 4.2-300 K) and magnetic field (in fields up to 10 kG at 4.2 K) dependences of the conductivity of two sets of multiwall carbon nanotubes with different average diameters (8-10 nm and 20-22 nm) heated at various temperatures (1600, 2200, 2600, 2800◦C) were investigated. Temperature dependences for nanotubes with average diameter 20-22 nm is typical for quantum corrections to conductivity of the systems with interaction electrons in two dimensional conductors with local disorder. For nanotubes with average diameter 8-10 nm temperature dependences corresponds to one-dimensional variable

range hopping conductivity (VRHC). The variation of annealing temperature of MWNTs influence on the contribution of corrections to conductivity and parameters of VRHC. The magnetoconductivity of MWNTs also depends on the annealing temperature and is less than that of highly oriented pyrographite. Annealed MWNTs with average diameter 20–22 nm has a positive magnetoconductivity.

MICROWAVE CHARACTERISTICS OF COMPOSITE RADIO MATERIALS ОN THE BASIS OF POLYMER AND CARBON STRUCTURES

O.А. Dotsenko*, V.I. Suslyaev*, V.L. Kuznetsov, I.N. Mazov, O.A. Кochetkova* (*Tomsk State University, Tomsk, Russia)

Doklady TIREET, 2(24) part 2, (2011) pp. 36-40.

In the paper there are given the results of research on frequency dependences of permittivity of composite radio materials on the basis of multiwall carbon nanotubes (MWCNT) in polymer matrix with different weight concentration. The measurements are completed on microwave by resonator method. The authors compared the weight concentration of MWCNT and graphite powder for composites with equal values of permittivity. It’s shown that for achievement of equal values of graphite powder permittivity it is required 10–20 times more.

LASER-INDUCED DIAMAGNETISM IN SUSPENSION OF ONION-LIKE CARBON PARTICLES

G.M. Mikheev*, V.L. Kuznetsov, K.G. Mikheev*, T.N. Mogileva*, S.I. Moseenkov (*Institute of Applied Mechanics, Izhevsk, Udmurtia, Russia)

Tech. Phys. Lett., 37(9) (2011) pp. 831-834.

It is experimentally established that the bleached fraction of a suspension of onion-like carbon (OLC) particles in N,N-dimethylformamide (DMF), which is clarified under the action of high-power pulsed laser radiation at λ = 1064 nm, is pushed out from inhomogeneous magnetic field. By changing the spatial arrangement of a permanent magnet relative to the point of laser action on the suspension, it is possible to control the direction of motion of the bleached fraction. The observed behavior can be explained by laser-stimulated chemical reactions between OLC and DMF, which lead to the formation of a new substance with pronounced diamagnetic properties.

 

HYDROXYLATED DETONATION NANODIAMOND: FTIR, XPS, AND NMR STUDIES

O. Shenderova*, A.M. Panich**, S.I. Moseenkov, S.C. Hens***, V.L. Kuznetsov, H.-M. Vieth***

(*International Technology Center, North Carolina, USA; **Ben-Gurion University of the Negev, Be’er Sheva, Israel; ***Free University of Berlin, Berlin, Germany)

J. Phys. Chem. C, 115(39) (2011) pp. 19005-19011.

Detailed and unambiguous characterization of the surface structure of detonation nanodiamond (DND) particles remains one of the most challenging tasks for the preparation of chemically functionalized nanodiamonds. In the present paper, a combination of FTIR, NMR, and XPS was used to characterize DND particles that were treated in a reduction reaction that results in the enrichment of hydroxyl and hydroxymethyl functional groups. FTIR spectra and quantum-chemistry modeling demonstrated that the vacuum treatment of the sample, with the purpose of the removing adsorbed water and other volatile contaminates, is mandatory to obtain the correct data on the nature and relative content of the -OH surface groups on DND. 13C and 1H NMR spectra show signals from the diamond core, hydroxyl, hydrocarbon groups, and moisture on the diamond surface. NMR data were taken for as-prepared DNDs, as well as those that were dried under vacuum conditions of 10–4 Torr, in order to distinguish between the NMR signal contributions due to moisture and other hydrogen-containing groups.

COMPARATIVE STUDY OF REFLECTANCE PROPERTIES OF NANODIAMONDS, ONION-LIKE CARBON AND MULTIWALLED CARBON NANOTUBES

V.L. Kuznetsov, S.I. Moseenkov, K.V. Elumeeva, T.V. Larina, V.F. Anufrienko, A.I. Romanenko*, O.B. Anikeeva*, E.N. Tkachev* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Phys. Status Solidi B, 248(11) (2011) pp. 2572-2576.

Carbon nanomaterials are the promising candidates for potential broadband limiting applications and extremely low reflectance coatings, particularly in the infrared, visible and UV spectral regions. In this paper the authors have performed the comparative study of diffuse reflectance of nanodiamond (ND), sp2/sp3 composites, onion-like carbon (OLC) and multiwalled carbon nanotubes (MWNTs) in visible and UV regions. ND, sp2/sp3 composites and OLC produced via high temperature annealing of the same set of NDs allow to vary sp2/sp3 carbon ratio, size of primary particle agglomerates and concentration of defects while MWNT set provides possibility to vary NT diameters and length, order/disorder degree (via high temperature MWNTS annealing). The diffuse reflectance of carbon nanomaterials depends mainly on the electronic configuration, defect concentration, size of graphene-like ordered fragments and agglomerates of nanoparticles along with their morphology.

ELECTROMAGNETIC RESPONSE OF POLYMER COMPOSITES WITH QUASI-SPHERICAL NANOCARBON INCLUSIONS: THEORY BELOW THE PERCOLATION THRESHOLD

P. Kuzhir*, A. Paddubskaya*, D. Bychanok*, G. Slepyan*, S. Maksimenko*, J. Macutkevic**, D. Seliuta**, G. Valusis**, J. Banys***, V.L. Kuznetsov, S.I. Moseenkov, O. Shenderova****, Ph. Lambin***** (*Institute for Nuclear Problem, Minsk, Belarus; **Semiconductor Physics Institute, Vilnius, Lithuania; ***University of Vilnius, Vilnius, Lithuania; ****International Technology Center, Raleigh, USA; *****FUNDP – University of Namur, Namur, Belgium)

J. Polym. Eng., 31(2-3) (2011) pp. 167-173.

The linear electromagnetic response of polymer composite with nanocarbon inclusions was modeled for a random multi-component system with particles and clusters of different shape and size. The results of the generalized effective medium Maxwell-Garnett theory below the percolation threshold demonstrate good coincidence with the experimental data for onion-like carbon-based polyurethane composites collected in a quasi-static regime (at 129 Hz) in a broad temperature range.

CARBON ONION COMPOSITES FOR EMC APPLICATIONS

P. Kuzhir*, A. Paddubskaya*, S. Maksimenko*, V.L. Kuznetsov, S.I. Moseenkov, A. Romanenko**, O. Shenderova***, J. Macutkevic****, G. Valusis****, P. Lambin***** (*Institute for Nuclear Problem, Minsk, Belarus; **Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; ***International Technology Center, Raleigh, USA; ****Semiconductor Physics Institute, Vilnius, Lithuania; *****FUNDP – University of Namur, Namur, Belgium)

IEEE Trans. Electromagn. Capability, 54(1) (2012) pp. 6-11.

A novel lightweight onion-like carbon (OLC)-based polymer composite with high electromagnetic (EM) shielding properties is presented. OLC have been produced via the large-scale production technology based on the annealing of detonation nanodiamond under vacuum conditions (or in inert atmosphere). EM shielding effectiveness has been tested in the frequency range of 26-37 GHz. The highest EM attenuation at 36.6 GHz reaching -34 dB was observed for polymethylmethacrylate films comprising 20 wt% of OLC. The shielding effectiveness data collected for microwave frequencies were found to correlate well with the electrical resistivity measurements by four-probe method as well as conductivity measurements provided by the broadband dielectric spectroscopy (20 Hz-3 GHz). It was proved experimentally that OLC EM shielding capacity can be optimized by varying the nanoonion cluster size and nanodiamond annealing temperature so that effective EM coatings can be produced. Both the experimental observations and theoretical simulations demonstrate that even small (smaller than percolation threshold) additions of OLC particles to a polymer host can noticeably modify the composite response to EM radiation.

MESOPOROUS COMPOSITE MATERIALS FROM ACTIVATED RICE HUSK CARBON AND MONTMORILLONITE

J.M. Jandosov*, Z.A. Mansurov*, M.A. Biisenbayev*, A.R. Kerinkulova*, Z.R. Ismagilov, N.V. Shikina, I.Z. Ismagilov, I.P. Andrievskaya (*Institute of Combustion Problems, Almaty, Kazakhstan)

Eurasian Chem.-Techn. J., 13(1-2) (2011) pp. 105-113.

Three different carbons were prepared from rice husk by steam activation at 700°C, H3PO4-activation followed by desilication or desilication followed by H3PO4-activation at 500°C. Honeycomb monoliths were obtained by mixing of a carbon with montmorillonite followed by extrusion, curing, calcination and leaching by alkaline solution. Obtained blocks were compared in terms of their morphology and elemental composition using data of SEM/EDX-analysis. From low temperature nitrogen adsorption study results it follows that prepared monoliths are characterized by SBET up to 700 m2/g (VΣ = 0.79 cm3/g) and pore size distribution shows the maximum around 4 nm. Methylene blue number is as high as 250 mg/g.

In situ STUDY ON CHANGES IN THE PHASE COMPOSITION OF A Ni–Cu CATALYST DURING GROWTH OF NITROGEN-CONTAINING CARBON NANOFIBERS

O.Yu. Podyacheva, A.N. Shmakov, Z.R. Ismagilov, V.N. Parmon

Doklady Phys. Chem., 439(1) (2011) pp. 127-130.

The work deals with in situ study of the phase changes in the Ni–Cu catalyst during the growth of N-CNFs in the process of decomposition of an ethylene–ammonia mixture with the use of a high-precision X-ray diffractometer equipped with a high-temperature camera–reactor. It was found that the formation of N-CNFs occurs through the stage of dissolution of carbon and nitrogen in particles of the Ni–Cu catalyst, but without formation of metal carbides.

STUDY OF OXYGEN GROUPS AT A POROUS CARBON SURFACE BY A NEW FAST INTERMITTENT THERMODESORPTION TECHNIQUE

F. Gaillard*, A. El Hachimi*, C. Descorme*, M. Besson*, J.-P. Joly*, E.M. Polyanskaya, O.P. Taran, V.N. Parmon (*Institut de Recherches sur la Catalyse et L’environnement de Lyon, Villeurbanne, France)

Carbon, 49(6) (2011) pp. 2062-2073.

A threshold thermodesorption method, named fast Intermittent TPD (ITPD), was used to study the evolution of CO2 and CO arising from the decomposition of oxygen groups at the surface of a porous carbon used in the wastewater treatment. Applied to the as-received carbon, CO2-ITPD provided clear evidence for six values of the apparent activation energy of oxygen group decomposition (Eapp): 139, 168, 206, 237, 270 and 290 kJ mol-1. Corresponding apparent pre-exponential factors (Aapp) were also determined. The data (Eapp and Aapp) derived from ITPD for the six desorption steps allowed a successful description of the complete TPD profile, considering a Gaussian narrow distribution of Eapp for each step. CO-ITPD also showed the presence of six (possibly seven) distinguishable steps upon CO thermal desorption and further demonstrated the interest of the fast ITPD technique for studying carbon surface chemistry. The TPD and ITPD profiles of the carbon treated with sodium hypochlorite showed: (i) a sharp increase in the amount of desorbed species, (ii) the prevailing presence of less stable oxygen groups, mainly carboxylic acids, giving rise to CO2 desorption at low temperature, and (iii) the progressive merging of the desorption steps detectable at low temperature upon increasing surface density of oxygen groups.

SIBUNIT-BASED CATALYTIC MATERIALS FOR THE DEEP OXIDATION OF ORGANIC ECOTOXICANTS IN AQUEOUS SOLUTIONS. II: WET PEROXIDE OXIDATION OVER OXIDIZED CARBON CATALYSTS

O.P. Taran, E.M. Polyanskaya, O.L. Ogorodnikova, С. Descorme*, М. Besson*, V.N. Parmon (*Institut de Recherches sur la Catalyse et L’environnement de Lyon, Villeurbanne, France)

Catal. Ind., 3(2) (2011) pp. 161-169.

The influence of the surface chemical composition of carbon catalysts prepared by oxidative treatment on the basis of the Sibunit-4 carbon material of the Sibunit family on their catalytic properties in the liquid-phase oxidation of formic acid by hydrogen peroxide was studied for the first time. Pure carbon samples were found to be active in the destruction of hydrogen peroxide and the oxidation of an organic substrate, and their activity decreased with an increase in the number of carboxyl and lactone groups on the surface of a carbon catalyst. Nevertheless, the rates of such processes on carbon catalysts are lower than in the presence of even small amounts of homogeneous Fe3+. It was shown that carbon samples accelerate or (to the contrary) inhibit the Fe3+-catalyzed peroxide oxidation of an organic substance, depending on the quantitative ratio of surface carboxyl and lactone groups and Fe3+ ions in the reaction solution. Possible acceleration and inhibition mechanisms for peroxide oxidation on carbon catalysts are discussed. The established influence of the surface chemical properties of carbon catalysts must be taken into account in the development of catalysts and processes for the oxidative purification of industrial wastewater.

MODERN APPROACHES TO THE PRODUCTION OF CARBON MATERIALS FROM VEGETABLE BIOMASS

P.M. Eletskii, V.A. Yakovlev, V.N. Parmon

Theor. Exp. Chem., 47(3) (2011) pp. 139-154.

Recent trends in methods for the preparation of porous carbon materials (PCM) from vegetable biomass by physical and chemical activation methods are analyzed. Data on the effect of activating agents and also other parameters on the textural characteristics of PCMs were classified. A new direction for the production of PCMs was discovered in the use of high-ash biomass.

 

SYNTHESIS OF CATALYTIC FILAMENTOUS CARBON ON A NICKEL/GRAPHITE CATALYST AND A STUDY OF THE RESULTING CARBON–CARBON COMPOSITE MATERIALS IN MICROBIAL FUEL CELLS

G.A. Kovalenko, L.G. Tomashevskaya*, T.V. Chuenko, N.A. Rudina, L.V. Perminova, A.N. Reshetilov* (*Skryabin Institute of the Biochemistry and Physiology of Microorganisms, Pushchino, Moscow oblast, Russia)

Kinet. Catal., 52(4) (2011) pp. 564-572.

The carbon-carbon composite materials obtained via the synthesis of catalytic filamentous carbon (CFC) on a Ni/graphite supported catalyst in the process of the pyrolysis of C3–C4 alkanes in the presence of hydrogen were systematically studied. The effects of the following conditions on the catalytic activity expressed as the yield of carbon (g CFC)/(g Ni) and on the character of CFC synthesis on graphite rods were studied: procedures for supporting Ni(II) compounds (impregnation and homogeneous precipitation), the concentrations of impregnating compouds (nickel nitrate, urea, and ethyl alcohol) in solution, graphite treatment (oxidation) conditions before supporting Ni(II) compounds, and the pyrolysis temperature of C3–C4 alkanes in the range of 400–600°C. Optimum conditions for preparing CFC/graphite composite materials, which are promising for use as electrodes in microbial fuel cells (MFCs), were chosen. The electrochemical characteristics of an MFC designed with the use of a CFC/graphite electrode (anode) and Gluconobacter oxydans glycerol-oxidizing bacteria were studied. The morphology of the surfaces of graphite, synthesized CFC, and also bacterial cells adhered to the anode was studied by scanning electron microscopy.

CATALYTIC PROPERTIES OF MASSIVE IRON-SUBGROUP METALS IN DICHLOROETHANE DECOMPOSITION INTO CARBON PRODUCTS

Yu.I. Bauman, I.V. Mishakov, R.A. Buyanov, A.A. Vedyagin, A.M. Volodin

Kinet. Catal., 52(4) (2011) pp. 547-554.

The formation of nanocarbon materials on massive nickel, nichrome, and some other alloys via the  carbide  cycle  mechanism  is  reported  using 1,2-dichloroethane decomposition as an example. The role of the physical stage of the carbide cycle is elucidated, and massive metal surface activation methods ensuring the realization of this stage are considered. The surface layer of massive nickel or some nickel alloys is most effectively activated by the action of chlorine resulting from the catalytic decomposition of 1,2-dichloroethane. It has been demonstrated by ferromagnetic resonance (FMR) spectroscopy that the activation of the massive metal surface in 1,2-dichloroethane decomposition to nanocarbon is due to the surface undergoing crystal chemical restructuring. The microstructuring of the surface yields fine Ni particles similar in size (0.2–0.3 μm) and shape, whose FMR spectra are anisotropic and have similar magnetic resonance parameters. Both chlorine-free and chlorinated hydrocarbons decompose over these particles via the carbide cycle mechanism. It is demonstrated that it is possible to design catalytic reactors packed with massive nickel or its alloy. The nanocarbon material obtained in such a reactor will not be contaminated by components of conventional catalyst supports (Al, Mg, etc.). The stable performance temperature of the catalyst will be increased, and this will allow the equilibrium outlet methane concentration to be reduced.

PROSPECTS OF MACRO- AND NANOCARBON FIBRES APPLICATION FOR UPDATING THE POLYETHYLENE OF PE80B MARK

L.Ya. Morova*, S.N. Popov*, E.S. Semenova*, M.E. Savvinova*, S.V. Solovyeva*, I.V. Mishakov, I.A. Streltsov (*Institute of Oil and Gas Problems, Yakutsk, Russia)

Proceed. Samara Sci. Center RAS, 13 (1(2)) (2011) pp. 386-389.

Results of the physicomechanical characteristics of composites on the basis of pipe polyethylene of PE80B mark, which has been reinforced by dispersed macro- and nanocarbon fibres are stated. It is established that efficiency of reinforcing effect of macrocarbon fibres on polymeric matrix is defined by their superficial characteristics - specific surface and presence of microdefects. It is shown that application of carbon nanofibres allows to raise adhesive interaction between composite components.

 

PREPARATION METHODS OF CATALYSTS FOR SYNTHESIS OF CARBON NANOFIBERS OF DIFFERENT MORPHOLOGICAL TYPES

A.A. Vedyagin, I.V. Mishakov, I.A. Streltsov, E.A. Zhukova, R.A. Buyanov

Proceed. Inst. Higher Educ., Ser.: Chem. Chem. Techn., 54(5) (2011) pp. 101-105.

Different preparation methods of nickel containing catalysts (co-precipitation of hydroxides, mechanochemical activation of oxides, impregnation of support and ultrasound sublimation of solutions) for CNF synthesis have been considered from viewpoint of possibility to control the diameter of obtained carbon nanofibers. The activity of catalysts in decomposition of propane as well as the morphology of obtained carbon products has been compared for different catalysts. The catalysts obtained by ultrasound sublimation have been shown to provide more thin CNF size distribution and maximum morphological homogeneity of fibers.

CARBON NANOFIBERS WITH LARGE SURFACE AREA: PECULIARITIES OF SYNTHESIS AND MORPHOLOGY

I.V. Mishakov, I.A. Streltsov, Yu.I. Bauman, A.A. Vedyagin, R.A. Buyanov

Proceed. Inst. Higher Educ., Ser.: Chem. Chem. Techn., 54(7) (2011) pp. 107-110.

The focus is made on methods for synthesis of ‘feathery’ carbon fibers from 1. 2-dichloroethane and C3–C4 hydrocarbons over nickel-containing catalysts. The   feathery   fibers   feature   a   kind   of   defect mesofragmentary packing of grapheme layers. As a result, they possess high specific surface area (300– 400 m2/g) and porosity (0.5–0.8 cm3/g) that are 3 to 5 times as large as those of traditional carbon nanofibers. The reaction of methanation is supposed as the key factor determining textural and morphological characteristics of this carbon material.

URANIUM AND ITS DECAY PRODUCTS IN RADIOACTIVE ANOMALIES OF OXIDIZED BROWN COALS (WESTERN PART OF KANSKO-ACHINSK BROWN COAL BASIN)

M.S. Melgunov, V.M. Gavshin*, E.V. Lazareva*, E.A. Melgunova (*Sobolev Institute of Geology and Mineralogy, Novosibirsk, Russia)

Radioprot., 46(6) (2011) S371-S376.

Vertical distribution of uranium and its decay products (226Ra and 210Pb) in the uppermost layers of the oxidised brown coals was studied for some deposits and natural outcrops of the Western part of the Kansko-Achinsk brown-coal basin. Abnormal accumulation of the mentioned radioactive elements is observed in all studied sites. Several types of radioactive anomalies are differed by the ratio of activities of 238U and 226Ra: 1) Equilibrium; 2) Radium; 3) Uranium. The depletion of 210Pb in the radioactive horizons of some sites indicates an active emanation of 222Rn in the underlying coal layers. Uranium besides the form sorbed on coal is presented in poral solutions. It says about its potential mobility and is confirmed experimentally. Radium is actively absorbed by the plants growing on radioactive coals.

 

 

Composite Sorbents

COMPOSITES CaCl2/SBA-15 FOR ADSORPTIVE TRANSFORMATION OF LOW TEMPERATURE HEAT: PORE SIZE EFFECT

I.S. Glaznev, I. Ponomarenko*, S. Kirik*, Yu.I. Aristov (*Institute of Chemistry and Chemical Technology, Krasnoyarsk, Russia)

Int. J. Refrigeration, 34(5) (2011) pp. 1244-1250.

Each specific cycle for adsorptive heat transformation (AHT) requires appropriate adsorbent which ensures the best realization of precisely this cycle. This paper addresses a synthesis of novel composite sorbents “CaCl2  confined  to  a  structured silicate SBA-15” with variable properties which appear to depend on the SBA pore size (8.1 and 11.8 nm). The equilibrium and dynamics of water sorption have been studied under typical conditions of isobaric stages of AHT cycle. Steep sorption isotherms are found, the pressure at which the sharp increase of water sorption is observed being higher in larger pores. This allows fine adjustment of sorbent properties to cycle boundary temperatures: the stronger water bounding by the salt confined to smaller pores results in the appropriate enhancement of the desorption and condensation temperatures. Comparison  of  the  new  composites  with  other adsorbents promising for AHT showed that mono-sized matrices are encouraging for both tailoring steplike sorption isotherms, managing the step position to fit given AHT cycle and fast water sorption.

WATER SORPTION BY THE CALCIUM CHLORIDE/SILICA GEL COMPOSITE: THE ACCELERATING EFFECT OF THE SALT SOLUTION PRESENT IN THE PORES

D.S. Ovoshchnikov, I.S. Glaznev, Yu.I. Aristov

Kinet. Catal., 52(4) (2011) pp. 620-628.

The kinetics of isothermal water sorption by the CaCl2/silica gel composite initiated by a small stepwise pressure rise over the sample has been investigated at a constant underlying plate temperature of 35°C. The initial portion of the kinetic curves is consistent with Fick’s diffusion model: the amount of sorbed water increases in proportion to the square root of the sorption time. This makes it possible to determine the effective diffusivity of water (Deff). At small amounts of sorbed water (w < 0.19 g/g), Deff changes slightly. The diffusivity of water in the composite pores (D) calculated for the same conditions is close to the Knudsen diffusivity of water vapor in mesopores. The Deff value grows with an increasing water content of the composite; that is, sorbed water accelerates water transport in the pores. This is likely due to the appearance of an extra diffusion channel, namely, diffusion through the aqueous solution of the salt, whose formation begins on the silica gel surface at w > 0.1 g/g. The contribution from this channel increases markedly when the amount of adsorbed water is above 0.25 g/g. This can be explained by the formation of the “connected” phase of the solution in the pores.

LOW TEMPERATURE HEAT CAPACITY OF THE SYSTEM “SILICA GEL–CALCIUM CHLORIDE–WATER”

Yu.I. Aristov, Yu.A. Kovalevskaya*,M.M. Tokarev, I.E. Paukov* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

J. Therm. Anal. Calorim., 103(2) (2011) pp. 773-778.

Heat capacity was measured for two composite systems based on silica gel KSK and calcium chloride confined to its pores. One corresponds to an anhydrous state, while another contains water bound with    the   salt   to   give   the   composition   of CaCl2·2.04H2O. The measurements were performed in the temperature range of 6–300 K with a vacuum adiabatic calorimeter. The smoothed experimental curves Cp (T) were used for calculating the calorimetric entropy and the enthalpy increment for both studied systems as well as the effective heat capacity associated only with water in the hydrated composite. The heat capacities Cp (298.15 K) of both composites were compared with those calculated as a linear addition of the heat capacities of silica gel and bulk calcium chloride (or its dihydrate) with appropriate weight coefficients.

NOVEL AMMONIA SORBENTS “POROUS MATRIX MODIFIED BY ACTIVE SALT” FOR ADSORPTIVE HEAT TRANSFORMATION: IV. DYNAMICS OF QUASI-ISOBARIC AMMONIA SORPTION AND DESORPTION ON BaCl2/VERMICULITE

J.V. Veselovskaya, M.M. Tokarev

Appl. Therm. Eng., 31(4) (2011) pp. 566-572.

A novel composite sorbent of ammonia BaCl2/vermiculite has recently been proposed and tested for adsorption cooling. The aim of this paper was a detailed study of its dynamic operation under conditions of isobaric stages of an adsorption chiller cycle. Experiments were performed by a Large Temperature Jump method at the ammonia pressures 5.8, 6.9, 12.2 and 15.8 bar. The ad- and desorption temperatures were fixed, respectively, at 15, 20, 25, 30, 35°C and 65, 70, 80, 90°C. All kinetic curves were described by an exponential function with a single characteristic time τ. The rate constant k = 1/τ was found to be a linear function of the temperature difference which drives the process, hence, heat transfer between the sorbent layer and the plate heat exchanger determines the process dynamics. The appropriate heat transfer coefficient does not depend on the ammonia pressure and process temperatures and equals 90 W/(m2·K). The data obtained were used for analyzing the dynamic performance of adsorption chiller with this composite as a solid sorbent. Appropriate recommendations on optimization of working cycle are made. The analysis showed that the specific cooling power could reach 690–860 W/kg at the cycle duration of 100–300 s.

COMPOSITE SORBENT OF METHANOL “LiCl IN MESOPOROUS SILICA GEL” FOR ADSORPTION COOLING: DYNAMIC OPTIMIZATION

L.G. Gordeeva, Yu.I. Aristov

Energy, 36(2) (2011) pp. 1273-1279.

A novel composite sorbent of methanol “LiCl in mesoporous silica gel” has recently been proposed for AC (adsorption cooling). Its testing in a lab-scale adsorption chiller resulted in the specific cooling power of 210-290 W/kg and the cooling COP of 0.32-0.4. Although these values are rather encouraging, a room for their enhancement still exists. The aim of this paper was a dynamic optimization of the composite performance in AC cycles. Dynamics of methanol sorption on loose grains of the LiCl/silica composites was studied by a Large Temperature Jump method under typical conditions of AC cycle. Effects of number of the sorbent layers, salt content, grain size and cycle boundary temperatures were studied. Physicochemical processes in the three-phase system (salt, solution, vapor) were shown to be quite complex and can strongly affect the dynamics of methanol ad-/desorption. Several obstacles which can retard the sorption were analyzed. Appropriate recommendations on improving the cycle dynamics, which concern optimal conversion degree, salt content and relative durations of ad- and desorption phases, were made.

Nanostructured-Nanocomposite Materials for SOFC Applicatrion

ADVANCED SINTERING TECHNIQUES IN DESIGN OF PLANAR IT SOFC AND SUPPORTED OXYGEN SEPARATION MEMBRANES

V.A. Sadykov, V.V. Usoltsev, Yu.E. Fedorova, N.V. Mezentseva, T.A. Krieger, N.F. Eremeev, M.V. Arapova, A.V. Ishchenko, A.N. Salanov, V.V. Pelipenko, V.S. Muzykantov, A. Ulikhin*, N. Uvarov*, O. Bobrenok**, A. Vlasov***, M. Korobeynikov***, A. Bryazgin***, A. Arzhannikov***, P. Kalinin***, O. Smorygo****, M. Thumm (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **Institute of Thermal Physics, Novosibirsk, Russia; ***Budker Institute of Nuclear Physics, Novosibirsk, Russia; ****Powder Metallurgy Institute, Minsk, Belarus; *****Karlsruhe Institute of Technology, Karlsruhe, Germany) In “Sintering/Book 1”, Ed. A. Lakshmanan, INTECH, Austria, Vienna, 2011, pp. 1-20.

Advanced sintering techniques based upon radiation-thermal sintering by e-beam action and microwave heating allow to provide required density and consolidation of thin functional layers in design of intermediate temperature solid oxide fuel cells and oxygen separation membranes. Due to decrease temperature and duration of sintering as compared with conventional sintering methods, such negative phenomena as variation of functional layers phase composition, their cracking and damage of metallic substrates were prevented. For oxide mixed ionic-electronic conducting composites advanced sintering provides developed interfaces which act as paths for fast oxygen diffusion required for considered applications. As the result, fuel cells and oxygen separation membranes manufactured using advanced sintering techniques demonstrate performance characteristics promising for the practical application. A novel approach to the design of planar gradient porous supports for the thin-film SOFCs and MIEC membranes is described. The support's thermal expansion is controlled by the creation of a two-component composite metal-ceramic foam structure. Thin MIEC membranes and SOFCs were prepared on the composite supports by the layerwise deposition of composite functional layers including complex fluorites and perovskites. Lab-scale studies demonstrated promising performance of both MIEC membrane and SOFC.

NANOCOMPOSITE CATALYSTS FOR STEAM REFORMING OF METHANE AND BIOFUELS: DESIGN AND PERFORMANCE

V.A. Sadykov, N.V. Mezentseva, G.M. Alikina, R.V. Bunina, V.V. Pelipenko, A.I. Lukashevich, Z.Yu. Vostrikov, V.A. Rogov, T.A. Krieger, A.V. Ishchenko, V.I. Zaikovsky, L.N. Bobrova, J. Ross*, O. Smorygo**, A. Smirnova***, B. Rietveld****, F. van Berkel**** (*University of Limerick, Limerick, Ireland; **Powder Metallurgy Institute, Minsk, Belarus; ***Eastern Connecticut State University, USA; ****Energy Research Center of the Netherlands, The Netherlands)

In “Nanocomposite Materials, Theory and Applications”, INTECH, Austria, Vienna, 2011,pp. 909-946.

Nanocomposite materials developed in this work based upon Ni and doped zirconia electrolyte allow to provide efficient and stable in-cell steam reforming of methane and ethanol required for IT SOFC as well as design of monolithic catalysts of transformation of biofuels into syngas. This is provided by optimization of their composition and preparation procedures ensuring developed interfaces between components activating fuel molecules (Ni, Ni-Pt/Ru alloys) and water molecules (complex oxides with perovskite and fluorite structures). Performance of best compositions supported as porous strongly adhering layers on anode cermets platelets, FeCr alloy gauzes and porous Ni-Al foam substrates was estimated as well and demonstrated to be high and stable to meet target of internal reforming of fuels in the intermediate temperature solid oxide fuel cells. No cracking or detachment of layers after reaction was observed. Analysis of methane reforming kinetics catalyzed by structured catalytic elements with supported nanocomposite layers has been carried out. Performance of catalytic plates in IR mode of ECN cell meets target of design of solid oxide fuel cells with internal reforming of methane by area specific resistance, activity and power density.

PEROVSKITES AND THEIR NANOCOMPOSITES WITH FLUORITE-LIKE OXIDES AS MATERIALS FOR SOLID OXIDE FUEL CELLS CATHODES AND OXYGEN-CONDUCTING MEMBRANES: MOBILITY AND REACTIVITY OF THE SURFACE/BULK OXYGEN AS A KEY FACTOR OF THEIR PERFORMANCE

V.A. Sadykov, S.N. Pavlova, T.S. Kharlamova, V.S. Muzykantov, N.F. Uvarov*, Yu.S. Okhlupin*, A.V. Ishchenko, A.S. Bobin, N.V. Mezentseva, G.M. Alikina, A.I. Lukashevich, T.A. Krieger, T.V. Larina, N.N.Bulgakov, V.M. Tapilin, V.D. Belyaev, E.M. Sadovskaya, A.I. Boronin, V.A. Sobyanin, O.F. Bobrenok*, A.L. Smirnova**, O.L. Smorygo***, J.A. Kilner**** (*Institute of Thermophysics, Novosibirsk, Russia; **University of Connecticut, Storrs, USA; ***Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; ***Powder Metallurgy Institute, Belarus; ****Imperial College London, London, UK) In “Perovskites: Structure, Properties and Uses”, Ed. M. Borowski, Nova Science Publishers, Inc, 2010, pp. 67-178.

This paper presents results of research aimed at elucidating factors controlling mobility and reactivity of the surface and bulk oxygen of complex perovskite-like AnBmOz oxides (manganites, ferrites, cobaltites, nickelates of La/Sr) and their nanocomposites with  fluorite-like oxides (doped ceria or zirconia) as related to their performance in the intermediate temperature solid oxide fuel cells (IT SOFC) cathodes and oxygen separation membranes. Real/defect structure and surface properties of these materials as a function of both composition, preparation route and sintering temperature were studied by combination of TEM with EDX, XRD, EXAFS, UV-Vis and XPS methods. Lattice oxygen mobility, strength of oxygen species bonding with the surface sites and their reactivity for both dispersed and dense materials were estimated by oxygen isotope exchange, temperature-programmed desorption and reduction by H2 and CH4. Coefficients of oxygen diffusion in dense materials were estimated by analysis of dynamics of the oxygen loss monitored by measurements of the weight loss or conductivity relaxations. For analysis of atomic-scale factors controlling oxygen bonding strength and mobility, quantum-chemical approaches including the Density Functional Theory (DFT) in spin-polarized SLDA approximation and semiempirical Interacting Bonds Method were applied.

DESIGN AND CHARACTERIZATION OF LSM/ScCeSZ NANOCOMPOSITE AS MIXED IONIC–ELECTRONIC CONDUCTING MATERIAL FOR FUNCTIONALLY GRADED CATHODES OF SOLID OXIDE FUEL CELLS

V.A. Sadykov, G.M. Alikina, A.I. Lukashevich, V.S. Muzykantov, V.V. Usoltsev, A.I. Boronin, S.V. Koshcheev, T.A. Krieger, A.V. Ishchenko, A. Smirnova*, O. Bobrenok**, N.F. Uvarov***

(*University of Connecticut, Storrs, USA; **Institute of Thermophysics, Novosibirsk, Russia; ***Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia)

Solid State Ionics, 192(1) (2011) pp. 540-546.

LSM/ScCeSZ nanocomposite was prepared via ultrasonic dispersion of the mixture of perovskite and fluorite powders in isopropanol in 1:1 ratio with addition of polyvinyl butyral. Studies of the real structure and surface property evolution at sintering under air up to 1100°C revealed some redistribution of elements between the phases without new phase formation. Sizes of both phase domains remain in nanorange even in the dense material, thus providing a developed perovskite–fluorite interface. The surface layer of nanocomposite is enriched by LSM. The oxygen mobility and reactivity estimated by the oxygen isotope exchange and O2 TPD exceed those for LSM suggesting a positive role of interfaces as fast oxygen migration paths. Button-cell tests with the LSM/ScCeSZ interlayer between LSNF and a thin ScYSZ layer covering Ni/YSZ cermet demonstrated a high and stable performance promising practical application promising for practical application.

DESIGN AND TESTING OF STRUCTURED CATALYSTS FOR INTERNAL REFORMING OF CH4 IN INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELLS (IT SOFC)

A.L. Smirnova*, V.A. Sadykov, N.V. Mezentseva, R.V. Bunina, V.V. Pelipenko, G.M. Alikina, T.A. Krieger, L.N. Bobrova, O.L. Smorygo**, F. van Berkel***, B. Rietveld*** (*Eastern Connecticut State University, Willimantic, USA; **Powder Metallurgy Institute, Minsk, Belarus; ***Energy Research Center of the Netherlands, The Netherlands)

ECS Trans., 35(1) (2011) pp. 2771-2780.

Procedures for the synthesis of nanocomposite anode materials comprised of Ni-YSZ promoted by doped Ce-Zr-O fluorite-like or La-Pr-Mn-Cr-O perovskite-like oxides and Pt/Ru were elaborated. Their composition, structure, reactivity, and catalytic properties in CH4 steam reforming were characterized using various techniques, such as SEM, TEM, EDX, TPR, and I-V testing in SOFC conditions. The optimized nanocomposites supported on compressed foam Ni-Al substrates demonstrated high and stable performance at H2O:CH4=1:2 ratio without coking or sintering. For the SOFC testing, the planar catalytic substrates with the surface area of 5x5 cm2 have been used. The demonstrated SOFC performance in the internal CH4 reforming mode was close to the performace obtained with the humidified hydrogen. The achieved power density was up to 300-800 mW/cm2 at 600-800°C meeting the targets of the area specific resistance, fuel efficiency, and power density.

 

SYNTHESIS AND CHARACTERIZATION OF DOPED APATITE-TYPE LANTHANUM SILICATES FOR SOFC APPLICATIONS

H. Gasparyan*,**, S. Neophytides**,D. Niakolas**, V. Stathopoulos***,****, T.S. Kharlamova, V.A. Sadykov, O. Van der Biest*****, E. Jothinathan*****, E. Louradour******, J.-P. Joulin******, S. Bebelis* (*University of Patras, Patras, Greece; **Institute of Chemical Engineering and High Temperature Chemical Processes, Patras, Greece; ***CERECO S.A.-Ceramics and Refractories Technological Development Company, Chalkida, Greece; ****Technological Educational Institute of Chalkida, Psahna, Greece; *****Katholieke Universiteit Leuven, Heverlee, Belgium;******CTI — Céramiques Techniques et Industrielles SA, Salindres, France)

Solid State Ionics, 192(1) (2011) pp. 158-162.

A series of iron- and/or aluminium-doped apatite- type lanthanum silicates (ATLS) La9.83Si6-x-yAlxFeyO26 ± δ (x = 0, 0.25, 0.75, and 1.5, y = 0, 0.25, 0.75, and 1.5) were synthesized using the mechanochemical activation (MA), solid state reaction (SSR), Pechini (Pe) and sol–gel (SG) methods. The total conductivity of the prepared materials was measured under air in the temperature range 600– 850°C using 4-probe AC impedance spectroscopy. Its dependence on composition, synthesis method, sintering conditions and powder particle size was investigated. It was found that for electrolytes of the same composition, those prepared via mechanochemical activation exhibited the highest total specific conductivity, which was improved with increasing Al- and decreasing Fe-content. The highest conductivity value at 700°C, equal to 2.04   ×   10-2   S   cm-1,   was   observed  for   the La9.83Si5Al0.75Fe0.25O26±δ electrolyte.La9.83Si4.5Fe1.5O26±δ electrolyte samples synthesized using the Pechini method exhibited higher conductivity when sintered conventionally than when spark-plasma sintering (SPS) was used.

APATITE TYPE LANTHANUM SILICATE AND COMPOSITE ANODE HALF CELLS

E. Jothinathan*, K. Vanmeensel*, J. Vleugels*, T.S. Kharlamova, V.A. Sadykov, S.N. Pavlova, G. Sourkouni**, C. Szepanski**, C. Argirusis**,***, O. Van der Biest* (*Katholieke Universiteit Leuven, Leuven, Belgium; **Clausthal University of Technology and Energieforschungszentrum, Goslar, Germany; ***National Technical University of Athens, Greece)

Solid State Ionics, 192(1) (2011) pp. 419-423.

Apatite type rare earth silicates are being extensively studied as electrolyte material for intermediate temperature solid oxide fuel cells (SOFC). In this paper results are presented on synthesis of Al and/or Fe-doped ATLS, the design of compatible anode materials, thermal expansion properties and co-sintering of half-cells from expansion matched materials using the advanced pulsed electric current sintering (PECS) technique. The issues related to the co-sintering of half cells have been addressed successfully by the combined use of nano powders and PECS.

NANOCOMPOSITE CATHODE MATERIALS FOR INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELLS

T.S. Kharlamova, S.N. Pavlova, V.A. Sadykov, Yu.N. Bespalko, T.A. Krieger, V.V. Pelipenko, V.D. Belyaev, G.M. Alikina, V.S. Muzykantov, Y. Okhlupin*, N. Uvarov*, A. Smirnova** (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **University of Connecticut, Storrs, USA)

ECS Transactions, 35(1) (2011) pp. 2331-2340.

The present paper is devoted to the optimization of composites (100-z) wt% La1-ySryFe0.7Ni0.3O3-δ -z wt% Ce0.9Gd0.1O2-δ (GDC) and study of the effect of Sr doping of perovskite and GDC content in the sample on structural and transport features of the composites. The results on the research of structural and microstructural features of the composits and their transport properties by using XRD, HRTEM, EDX analysis, electrical conductivity measurements, oxygen isotope heteroexchange and conductivity as well as weight relaxation techniques are presented and discussed.

THE EFFECT OF PHASE COMPOSITION ON THE TRANSPORT PROPERTIES OF COMPOSITES Lao.8Sio.2Feo.7Nio.303-8 - Ceo.9Gdo.1O1.95

Yu.S. Okhlupin*, M.V. Ananyev**, N.F. Uvarov*, Yu.N. Bespalko, S.N. Pavlova, V.A. Sadykov (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **Institute of High-Temperature Electrochemistry, Yekaterinburg, Russia)

Russ. J. Electrochem., 47(6) (2011) pp. 663-670.

Full conductivity, diffusion and oxygen exchange processes in composites (100-x)La0.8Sr0.2Fe0.7Ni0.3O3-s - xCe0.9Gd0.1O1.95 (x is the volume fraction, 0 < x < 71.1%) at 700°C over the oxygen partialpressure range from 0.2 to 3 × 10-3 atm are studied by the electrical conductivity relaxation method. The composites’ conductivity was shown to decrease monotonically with the increasing of Ce0.9Gd0.1O1.95 fraction, while the oxygen chemical diffusion coefficient increased. The oxygen exchange constant is higher for the composites than for the individual phases of La0.8Sr0.2Fe0.7Ni0.3O3-s and Ce0.9Gd0.1O1.95. Possible reason of the dependence of the parameters Dchem and k chem on the temperature, oxygen pressure, and the composite composition is the effect of the interface on the oxygen transfer processes. Most effective oxygen transfer occurs in the composites whose composition approaches La0.8Sr0.2Fe0.7Ni0.3O3-s - Ce0.9Gd0.1O1.95(x = 71%).

STUDIES OF OXYGEN TRANSPORT MECHANISM IN ELECTROLYTES BASED ON DOPED LANTHANUM SILICATE WITH APATITE STRUCTURE USING TECHNIQUES OF OXYGEN ISOTOPIC HETEROEXCHANGE AND IMPEDANCE SPECTROSCOPY

V.A. Sadykov, T.S. Kharlamova, N.V. Mezentseva, S.N. Pavlova, E.M. Sadovskaya, V.S. Muzykantov, Yu.N. Bespalko, V.V. Usoltsev, E.G. Zevak, T.A. Krieger, A.V. Ishchenko, N.F. Uvarov*, A.S. Ulikhin*, M.V. Chaikina**, С Argirusis***'*** (*Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; **Clausthal University of Technology, Clausthal-Zellerfeld, Germany; ***National Technical University of Athens, Athens, Greece)

Russ. J. Electrochem., 47(4) (2011) pp. 427-441.

The work presents the results of studying the mechanism of oxygen transport for a new promising class  of oxygen-containing  electrolytes  based  on

lanthanum silicate with an apatite structure using impedance spectroscopy and isotopic oxygen heteroexchange. At 1000 K, in the case of samples with an optimum composition including codoped Fe and Al, о ~ 3 × 10-3 to 10-2 S/cm and D* reaches ~ 10-8 cm2/s, which is close to the values of YSZ and Ce09Gd01O2-g (GDC). Lower energies of conductivity activation and oxygen diffusion for doped apatites ( 0.5-0.8 eV instead of ~ 1 eV for GDC) and also equivalence as regards exchange of all oxygen atoms within apatite agree with the model, in which oxygen mobility is determined by a nonlinear cooperative migration process of oxygen atoms with fast exchange between interstitial and regular sites.

DESIGN OF MEDIUM-TEMPERATURE SOLID OXIDE FUEL CELLS ON POROUS SUPPORTS OF DEFORMATION STRENGTHENED Ni-Al ALLOY

V.A. Sadykov, V.V. Usoltsev, Yu.E. Fedorova, V.A. Sobyanin, P.V. Kalinin*, A.V.  Arzhannikov*, A.Yu. Vlasov**, M.V. Korobeinikov**, A.A. Bryazgin**, A.N. Salanov,

M.R. Predtechenskii***, O.F. Bobrenok***, A.S. Ulikhin****, N.F. Uvarov****,

O.L. Smorygo*****, A.F. Il’yushchenko*****, V.Yu. Ul’yanitskii******, S.B. Zlobin****** (*Novosibirsk State University, Novosibirsk, Russia; **Budker Institute of Nuclear Physics, Novosibirsk, Russia; ***Institute of Thermal Physics, Novosibirsk, Russia; ****Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; *****Institute of Powder Metallurgy, Minsk, Belarus; ******Lavrent ’ev Institute of Hydrodynamics, Novosibirsk, Russia)

Russ. J. Electrochem., 47(4) (2011) pp. 488-493.

An approach was developed towards design of medium-temperature solid-oxide fuel cells based on a deformation strengthened Ni-Al alloy. Methods of sintering were described that allowed obtaining layers of complex oxides with ionic and mixed conductivity and with regulated porosity in the range of 40-1%. Power density of a fuel cell on a metallic support reaches 500 mW/cm2 already at 700°C when humid H2 was used as fuel and air was used as an oxidant. Analysis of fuel cell cross-section after tests showed absence of fractures, flaking, and new phases with low conductivity, which proves good compatibility of all materials used in fuel cell design.

SOLID OXIDE FUEL CELL COMPOSITE CATHODES BASED ON PEROVSKITE AND FLUORITE STRUCTURES

V.A. Sadykov, N.V. Mezentseva, V.V. Usoltsev, E.M. Sadovskaya, A.V. Ishchenko, S.N. Pavlova, Yu.N. Bespalko, T.S. Kharlamova, E.G. Zevak, A.N. Salanov, T.A. Krieger, V.D. Belyaev, O. Bobrenok*, N. Uvarov**, Yu. Okhlupin**, O. Smorygo***, A. Smirnova****, P. Singh*****, A. Vlasovh******, M. Korobeynikov******, A. Bryazgin******, P. Kalinin******, A. Arzhannikov****** (*Institute of Thermal Physics, Novosibirsk, Russia; **Institute of Solid State Chemistry and Mechanochemistry, Novosibirsk, Russia; ***Powder Metallurgy Institute, Minsk, Belarus; ****Eastern Connecticut State University, Willimantic, USA; *****University of Connecticut, Storrs, USA; ******Budker Institute of Nuclear Physics, Novosibirsk, Russia)

J. Power Sources, 196(17) (2011) pp. 7104-7109.

This work presents the results related to the functionally graded fluorite (F) - perovskite nanocomposite cathodes for IT SOFC. Nanocrystalline fluorites (GDC, ScCeSZ) and perovskites (LSrMn, LSrFNi) were synthesized by Pechini method. Nanocomposites were prepared by the ultrasonic dispersion of F and P powders in isopropanol with addition of polyvinyl butyral. Different techniques for deposition and sintering of functionally graded cathode materials were applied including traditional approaches as well as original methods, such as radiation-thermal sintering under electron beam or microwave radiation. Morphology, microstructure and elemental composition of nanocomposites was characterized by XRD and HRTEM/SEM with EDX. Even for dense composites, the sizes of perovskite and fluorite domains remain in the nanorange providing developed P-F interfaces. Oxygen isotope heteroexchange and conductivity/weight relaxation studies demonstrated that these interfaces provide a path for fast oxygen diffusion. The redistribution of the elements between P and F phases in nanocomposites occurs without formation of insulating zirconate phases. Button-size fuel cells with nanocomposite functionally graded cathodes, thin YSZ layers and anode Ni/YSZ cermet (either bulk or supported on Ni-Al foam substrates) were manufactured. For optimized composition and functionally graded design of P-F nanocomposite cathodes, a stable performance in the intermediate temperature range with maximum power density up to 0.5 W cm-2 at 700°C in wet H2/air feeds was demonstrated.

Photocatalytic and Related Processes

GLOSSARY OF TERMS USED IN PHOTOCATALYSIS AND RADIATION CATALYSIS (IUPAC RECOMMENDATIONS 2011)

S.E. Braslavsky*, A.M. Braun**, A.E. Cassano***, A.V. Emeline****, M.I. Litter*****, L. Palmisano******, V.N. Parmon, N. Serpone******* (*Max Planck Institute for Bioinorganic Chemistry, Mülheim/Ruhr, Germany; **University of Karlsruhe, Karlsruhe, Germany; ***Universidad Nacional del Litoral, Santa Fe, Argentina; ****V.A. Fock Institute of Physics, St. Petersburg, Russia; *****National Atomic Energy Commission, Buenos Aires, Argentina; ******University of Palermo, Palermo, Italy; *******Concordia University, Montreal, Canada and University of Pavia, Pavia, Italy)

Pure Appl. Chem., 83(4) (2011) pp. 931-1014.

This glossary of terms covers phenomena considered under the very wide terms photocatalysis and radiation catalysis. A clear distinction is made between phenomena related to either photochemistry and photocatalysis or radiation chemistry and radiation catalysis. The term “radiation” is used here as embracing electromagnetic radiation of all wavelengths, but in general excluding fast-moving particles. Consistent definitions are given of terms in the areas mentioned above, as well as definitions of the most important parameters used for the quantitative description of the phenomena. Terms related to the up-scaling of photocatalytic processes for industrial applications have been included. This Glossary should be used together with the Glossary of terms Used in Photochemistry, 3rd edition, IUPAC Recommendations 2006: (doi:10.1351/pac200779030293) as well as with the IUPAC Compendium of Chemical Terminology, 2nd ed. (the “Gold Book”, 2006– doi:10.1351/goldbook) because many terms used in photocatalysis are defined in these documents.

PHOTOCHEMISTRY OF A 6 '-CYANOSUBSTITUTED SPIRONAPHTHOOXAZINE: PHOTO-INDUCED DECAY OF AN OPEN FORM

M.I. Nikolaeva, V.V. Korolev*, E.A. Pritchina*, E.M. Glebov*, V.F. Plyusnin*, A.V. Metelitsa**, N.A. Voloshin**, V.I. Minkin** (*Institute of Chemical Kinetics and Combustion, Novosibirsk, Russia; **Southern Federal University, Rostov-on-Don, Russia)

J. Phys. Org. Chem., 24(9) (2011) pp. 833-842.

Photochemistry of three 6'-cyanosubstituted spironaphthooxazines (SNO) in ethanol matrices at 77 K was studied by means of ultraviolet (UV) and erythrocyte sedimentation rate (ESR) spectroscopy and quantum chemistry. The quantum yield of the open form photolysis is found to be 0.01-0.02, which is high enough for 77 K. For one of the SNO, the formation of a merocyanine form radical was observed. The radicals were formed by an H atom abstraction from the solvent molecule to the light-excited merocyanine isomers. The formation of a merocyanine radical represents a new specific channel of photochemically induced degradation of spirooxazines.

PHOTOCHROMISM OF 6'-CYANOSUBSTITUTED SPIROOXAZINES IN FROZEN ALCOHOL MATRICES

M.I. Nikolaeva, V.V. Korolev*, E.A. Pritchina*, E.M. Glebov*, V.F. Plyusnin*, A.V. Metelitsa**, N.A. Voloshin**, V.I. Minkin** (*Institute of Chemical Kinetics and Combustion, Novosibirsk, Russia; **Institute of Physical and Organic Chemistry, Southern Federal University, Rostov-on-Don, Russia)

Kinet. Catal., 52(2) (2011) pp. 202-209.

For three 6'-cyanosubstituted spironaphthooxazines, spectral characteristics of an open form and quantum yields of photoisomerization were determined both at room temperature and in frozen alcohol matrices. Spironaphthooxazines have demonstrated fairly high (0.01–0.02) quantum yields of open form appearance at 77 K. The observed peculiarities of the open form UV spectra were explained by the temperature dependence of the open form isomers distribution. Partial stabilization of the nonequilibrium isomers of an open form in the low-temperature matrices was revealed.

PHOTOINDUCED CATALYTIC SYNTHESIS OF BIOLOGICALLY IMPORTANT METABOLITES FROM FORMALDEHYDE AND AMMONIA UNDER PLAUSIBLE “PREBIOTIC” CONDITIONS

I.V. Delidovich, O.P. Taran, A.N. Simonov, L.G. Matvienko, V.N. Parmon

Adv. Space Res., 48(3) (2011) pp. 441-449.

The article analyzes new and previously reported data on several catalytic and photochemical processes yielding biologically important molecules. UV-irradiation of formaldehyde aqueous solution yields acetaldehyde, glyoxal, glycolaldehyde and glyceraldehyde, which can serve as precursors of more complex biochemically relevant compounds. Photolysis of aqueous solution of acetaldehyde and ammonium nitrate results in formation of alanine and pyruvic acid. Dehydration of glyceraldehyde catalyzed by zeolite HZSM5-17 yields pyruvaldehyde. Monosaccharides are formed in the course of the phosphate-catalyzed aldol condensation reactions of glycolaldehyde, glyceraldehyde and formaldehyde. The possibility of the direct synthesis of tetroses, keto-and aldo-pentoses from pure formaldehyde due to the combination of the photochemical production of glycolahyde and phosphate-catalyzed carbohydrate chain growth is demonstrated. Erythrulose and 3-pentulose are the main products of such combined synthesis with selectivity up to 10%. Biologically relevant aldotetroses, aldo- and ketopentoses are more resistant to the photochemical destruction owing to the stabilization in hemiacetal cyclic forms. They are formed as products of isomerization of erythrulose and 3-pentulose. The conjugation of the concerned reactions results in a plausible route to the formation of sugars, amino and organic acids from formaldehyde and ammonia under presumed `prebiotic' conditions.

PHOTOCHEMICAL ACTIVITY OF THE ADSORBED AEROSOL, PRODUCED FROM PERICLASE (MgO) CRYSTAL UNDER AMBIENT AIR

V.S. Zakharenko, E.B. Daibova* (*Tomsk State University, Tomsk, Russia)

Atmos. Oceanic Opt., 24(6) (2011) pp. 516-520.

The adsorption and photoadsorption properties of aerosol particles, produced by grinding of periclase crystal (MgO) under ambient air, were studied. The composition analysis of adsorption surface layer formed by grinding of crystal is carried out. The kinetics of dark and photo adsorption of oxygen and carbon monoxide including 13CO were considered. The quantum yield quantities and spectral dependencies of photoadsorption were determined. The comparison of photoadsorption properties of samples used in this work and magnesium oxide powders produced by traditional ways was realized.

STRUCTURED CATALYSTS FOR PHOTO-FENTON OXIDATION OF ACETIC ACID

D. Sannino*, V. Vaiano*, P. Ciambelli*, L.A. Isupova (*University of Salerno, Fisciano, Italy)

Catal. Today, 161(1) (2011) pp. 255-259.

In this work photo-Fenton oxidation of acetic acid, was carried out on perovskites based structured catalysts, in the presence or in the absence of low amounts of Pt. Homogeneous photo-Fenton reaction by ferrioxalate complex has been also performed. The comparison of homogeneous and heterogeneous photo-Fenton oxidation indicates that the use of a heterogeneous structured catalyst greatly improves the total organic carbon (TOC) removal and leads to a more effective use of H2O2. The rate of TOC removal during the runtime decreased because of the occurring side H2O2 decomposition to O2 that subtracts the oxidant to the photo-Fenton reaction. Moreover it allows enlarging the pH range of operation without the formation of sludge or significant metal leaching. LaFeO3 and Pt/LaMnO3 resulted the best catalysts for this process in terms of reaction rate.

 

PHOTO-FENTON OXIDATION OF ACETIC ACID ON SUPPORTED LaFeO3 AND Pt/LaFeO3 PEROVSKITES

D. Sannino*, V. Vaiano*, L.A. Isupova, P. Ciambelli* (*University of Salerno, Fisciano,

Italy)

Chem. Eng. Trans., 25(2) (2011) pp. 1013-1018.

Photo-Fenton process uses Fe2+ as homogeneous catalyst, hydrogen peroxide and UV light to mineralize organic pollutants by the formation of highly reactive hydroxyl radicals. Several limitations to this process are present, such as the limited operational pH range to avoid oxyhydroxide sludge formation and the catalyst recovery. Heterogeneous photo-Fenton process based on structured catalyst can avoid a subsequent separation stage, overcoming these disadvantages. In this work, the comparison of performances of LaFeO3 and Pt/LaFeO3 perovskites supported on different honeycomb monoliths, made of cordierite or corundum, were studied. Photo-Fenton oxidation of acetic acid showed that LaFeO3 supported on corundum honeycomb was more active than on cordierite monolith. The addition of Pt on catalysts did not help to increase their performance in the studied reaction. Photo-Fenton oxidation tests carried out on catalysts having different content of LaFeO3 evidenced the existence of an optimal loading of active phase.

THE INFLUENCE OF CORONA ELECTRODES THICKNESS ON THE EFFICIENCY OF PLASMACHEMICAL OXIDATION OF ACETONE

M.N. Lyulyukin, A.S. Besov, A.V. Vorontsov

Plasma Chem. Plasma Process., 31(1) (2011) pp. 23-39.

Current–voltage characteristics (CVC) and acetone vapors oxidation in atmospheric pressure corona discharge (CD) of negative and positive polarity were studied in double wires-to-plate geometry. Negative CD was more stable than positive one towards breakdown and allowed to reach higher current. CVC for negative CD can be well described by model for cylindrical geometry with correction in one coefficient only. The ignition voltage of negative CD obeys Peek’s law. The rate of acetone vapors oxidation increased with the increase of corona wire radius in the range of discharge power 15–60 W. The

highest oxidation rate was obtained at power 60 W, negative polarity and wire radius 400 lm but the highest energetic efficiency (g/kWh) was obtained at maximum wire radius (400 lm) and minimum power level (15 W). The oxidation rate was directly proportional to the volume of discharge area which grows together with the increase of wire radius.

INFLUENCE OF THE METHOD OF PLATINUM DEPOSITION ON ACTIVITY AND STABILITY OF Pt/TiO2 PHOTOCATALYSTS IN THE PHOTOCATALYTIC OXIDATION OF DIMETHYL METHYLPHOSPHONATE

E.A. Kozlova, T.P. Lyubina, M.A. Nasalevich, A.V. Vorontsov, A.V. Miller, V.V. Kaichev, V.N. Parmon

Catal. Commun., 12(7) (2011) pp. 597-601.

Gas-phase photocatalytic oxidation of organophosphorous compound dimethyl

methylphosphonate was carried out in a flow reactor on platinized TiO2 Degussa P25. Platinization was performed by soft chemical reduction (SCR) and photodeposition (PD) techniques. Dispersion and chemical state of platinum were studied by X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). It was found that SCR gave mostly metallic platinum, whereas PD gave only Pt2+ form. During the oxidation, the state of platinum on a SCR catalyst remained unchanged, which determined its good stability. The catalyst with PD platinum deactivated quite fast due to aggregation of Pt particles. The SCR technique was found to provide better stability and activity.

PARAMETRIC STUDIES OF DIETHYL PHOSPHORAMIDATE PHOTOCATALYTIC DECOMPOSITION OVER TiO2

B. Sun*, A.V. Vorontsov, P.G. Smirniotis*

(*University of Cincinnati, Cincinnati, USA)

J. Hazard. Mater., 186(2-3) (2011) pp. 1147-1153.

The present study is focused on influences of parameters including pH, temperature, TiO2 catalyst concentration, and reactant concentration on the rate of photocatalytic diethyl phosphoramidate (DEPA) decomposition with Hombikat UV 100 (HK) and Degussa P25 (P25) TiO2. Total mineralization of DEPA is observed. Two regimes of pH, namely in acid and near-neutral environments were found where maximum total carbon (TC) decomposition was observed. The electrostatic effects on adsorption over the TiO2 surface explain the above phenomena. The maximum rate is observed for P25 at DEPA concentration 1.3 mM whereas the rate grows continuously with DEPA concentration rise for HK. The temperature dependence of TC decomposition rate in the range of 15–63°C with both HK and P25 follows the Arrhenius equation. The activation energy for total carbon decomposition with HK and P25 are 29.5 ± 1.0 and 24.3 ± 3.1 kJ/mol, respectively. The decomposition rate of DEPA is larger over P25 than over HK. The rate over P25 increases faster than that with HK for each unit of the titania added when the TiO2 concentration is less than 375 mg/l. The higher light absorption and particles aggregation of P25 are responsible for the decrease of reaction rate the authors observed at catalyst concentration above a certain level. In contrast, the rate over HK increases monotonically with the concentration of the photocatalyst used.

DEVELOPMENT OF MULTISTAGE PHOTOCATALYTIC REACTORS FOR AIR PURIFICATION

D.V. Kozlov, A.V. Vorontsov

Chem. Sustain. Devel., 19(1) (2011) pp. 67-76.

The basic principles of the performance of catalysts in the processes of profound oxidation of organic compounds present in the air are considered. Within the framework of Langmuir-Hinshelwood model, the authors calculated the kinetic parameters of photooxidation of a number of compounds (rate constants and adsorption constants) and then used them in the development of reactors for air purification. It was demonstrated that in order to increase the rate of photocatalytic oxidation, it is necessary to optimize the geometry of the photocatalytic filter, and to use inorganic air-permeable membranes (foam ceramics and glas cloth) as supports for the photocatalyst. In addition, the efficiency of air purification can be increased due to the use of multistage reactors in which the air to be purified passes consecutive stages of electrostatic filtration, adsorption and photocatalytic purification. An example of implementation of the proposed concept of multistage purification of the air at the industrial enterprise SPA Luch (Novosibirsk) is described.

SIZE EFFECTS IN PHOTOEXCITATION OF TRIPLET STATES OF AMMONIUM TETRAPHENYLBORATE

V.A. Nadolinny*, O.V. Antonova*, E.A. Il’inchik*, M.K. Kovalev, M.S. Melgunov, A.P. Yelisseev**, A.A. Ryadun* (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia; **Sobolev Institute of Geology and Mineralogy, Novosibirsk, Russia)

Phys. Solid State, 53(2) (2011) pp. 284-291.

This paper reports on the results of complex investigations of photoexcited states of ammonium tetraphenylborate, which are characterized by self-sensitized luminescence. It has been established that the excitation by UV light at 77 K leads to the formation of stable triplet states due to the capture of electrons on electron traps. The EPR and luminescence excitation spectra exhibit the formation of a set of triplet states with different distances between electrons and holes. The performed investigations give grounds to affirm that, in bulk samples, cations in the structure of ammonium tetraphenylborate are electron traps. When the size of the ammonium tetraphenylborate sample is changed to 6 and 3 nm, the capture of excited electrons on sorbed oxygen molecules becomes dominant. In this case, the appearance of the spectrum of O2- anion radicals has been detected by the EPR method. The proposed interpretation of the observed effects has been confirmed by the thermoluminescence data on the recombination of electron-hole pairs, which correlate with a change in the intensity of the EPR spectra during annealing.

Polymerization Catalysts and Polymer Materials

KINETICS OF ETHYLENE POLYMERIZATION IN THE PRESENCE OF A HOMOGENEOUS CATALYST BASED ON A bis(PHENOXYIMINE) COMPLEX OF ZIRCONIUM(IV)

A.A. Barabanov, N.V. Semikolenova, M.A. Matsko, L.G. Echevskaya, V.A. Zakharov

Kinet. Catal., 52(2) (2011) pp. 217-221.

Changes in the molecular-weight characteristics of the product of ethylene polymerization in the course of reaction in the presence of a homogeneous catalytic system and in the number and reactivity of catalyst active sites were studied. The catalytic system consisted of bis[N-(3-tert-butylsalicylidene)anilinato] zirconium dichloride and methylalumoxane as an activator. This catalytic system exhibited the signs of unsteady-state conditions: the rate of polymerization dramatically decreased as the reaction time increased. At the onset of polymerization (to 5 min), the catalyst was single-site, and it produced low-molecular-weight polyethylene with Mw = (4–10) × 103 g/mol. The fraction of active sites at the initial point in time was as high as 11% based on the initial amount of the zirconium complex. The reactivity of these centers was very high (the rate constant of polymer chain growth was 5.4 × 104 l mol-1 s-1 at 35°C). As the polymerization time increased, the number of active sites decreased and the molecular-weight distribution of polyethylene broadened because of the decay of a portion of initial centers and the formation of new centers that produced high-molecular-weight polyethylene with Mw to 130 × 104 g/mol. The propagation rate constant measured at a sufficiently long polymerization time (20 min) was lower than that at the initial point in time; this fact suggests the much lower reactivity of the new active sites.

INFLUENCE OF TRIISOBUTYLALUMINUM ON THE POLYMERIZATION OF ETHYLENE BY SiO2-SUPPORTED ANSA-ZIRCONOCENE CATALYSTS

V.N. Panchenko, L.G. Echevskaya, V.A. Zakharov, M.A. Matsko

Appl. Catal., A., 404(1-2) (2011) pp. 47-53.

Catalysts for the polymerization of ethylene, which contain rac-Me2Si(Ind)2ZrCl2 (SBIZrCl2) bound to methylalumoxane-pretreated SiO2 supports (SiO2/MAO/SBIZrCl2), were studied with respect to leaching of zirconocene and MAO into heptane solutions caused by triisobutylaluminum (TIBA). The latter is found to solubilize surface-bound MAO and zirconocene components, such that the Al content in the solid catalysts is reduced by 15–40 wt% and their Zr content by 50–60 wt%. Consequently, ethylene polymerization with such TIBA-containing catalyst systems occurs both on the surface of the solid catalyst and in the solution phase. Polymerization in solution is favored by high MAO contents in the SiO2 carrier. Polymerization in solution leads to polyethylene (PE) products with lower molecular masses than polymerization on the support surface; this is the main cause of formation of PE with bimodal molecular mass distribution when ethylene is polymerized with SiO2/MAO/SBIZrCl2 catalysts co-activated by TIBA. It is proposed that the co-activator TIBA interacts with surface-bound MAO to modify MAO in such a manner that it becomes soluble in aliphatic hydrocarbons and capable of solubilizing some active zirconocene component.

ETHYLENE POLYMERIZATION OVER SUPPORTED TITANIUM-MAGNESIUM CATALYSTS: EFFECT OF POLYMERIZATION PARAMETERS ON THE MOLECULAR WEIGHT DISTRIBUTION OF POLYETHYLENE

M.I. Nikolaeva, T.B. Mikenas, M.A. Matsko, L.G. Echevskaya, V.A. Zakharov

J. Appl. Polym. Sci., 122(5) (2011) pp. 3092-3101.

The data on the effects of polymerization duration, cocatalyst, and monomer concentrations upon ethylene polymerization in the absence of hydrogen, and the effect of an additional chain transfer agent (hydrogen) on the molecular weight (MW), molecular weight distribution (MWD), and content of vinyl terminal groups for polyethylene (PE) produced over the supported titanium-magnesium catalyst (TMC) are obtained. The effects of these parameters on nonuniformity of active sites for different chain transfer reactions are analyzed by deconvolution of the experimental MWD curves into Flory components. It has been shown that the polymer MW grows, the MWD becomes narrower and the content of vinyl terminal groups in PE increases with increasing polymerization duration. It is assumed to occur due to the reduction of the rate of chain transfer with AlEt3 with increasing polymerization duration. The polydispersity of PE is found to rise with increasing AlEt3 concentration and decreasing monomer concentration due to the emergence of additional low molecular weight Flory components. The ratios of the individual rate constants of chain transfer with AlEt3, monomer and hydrogen to the propagation rate constant have been calculated.

SUPPORTED ZIEGLER TYPE CATALYSTS FOR PRODUCTION OF POLYETHYLENE (PE): EFFECT OF THE COMPOSITION OF THE ACTIVE COMPONENT, THE METHODS OF ITS FORMATION, AND THE USE OF MODIFYING AGENTS ON CATALYTIC ACTIVITY AND MOLECULAR STRUCTURE OF PE AND COPOLYMERS OF ETHYLENE WITH α-OLEFINS

T.B. Mikenas, V.A. Zakharov, V.E. Nikitin, L.G. Echevskaya, M.A. Matsko

Catal. Ind., 3(2) (2011) pp. 122-127.

Summarized results are presented on studying the formation of the active component of supported Ziegler type catalysts, investigation the effect of the composition of these catalysts on the molecular mass characteristics of PE, and seeking new methods for producing catalysts with optimum morphology.

ANALYSIS OF THE MOLECULAR STRUCTURE OF ETHYLENE HEXENE-1 COPOLYMERS PRODUCED OVER HIGHLY ACTIVE SUPPORTED ZIEGLER–NATTA CATALYSTS

M.A. Matsko, L.G. Echevskaya, T.B. Mikenas, M.I. Nikolaeva, M.P. Vanina, V.A. Zakharov

Catal. Ind., 3(2) (2011) pp. 109-115.

The mechanical and rheological properties of ethylene α-olefin copolymers are governed by a molecular and supramolecular structure that depends on its molecular weight characteristics, comonomer concentration, and the uniformity of branching distributions for polymer chains with different molecular weights (compositional heterogeneity). Using state-of-the-art methods, the authors studied the parameters of molecular weight distribution, molecular structure, and compositional heterogeneity of ethylene hexane-1 copolymers with different compositions, produced over highly active supported Ti–Mg and V–Mg Ziegler–Natta catalysts, and showed the possibility of controlling these parameters to improve the quality of the resulting polymers.

STUDY OF THE COMPOSITIONAL HETEROGENEITY OF ETHYLENE-1-HEXENE COPOLYMERS VIA THERMAL FRACTIONATION WITH THE USE OF DIFFERENTIAL SCANNING CALORIMETRY

M.A. Matsko, M.P. Vanina, L.G. Echevskaya, V.A. Zakharov

Polym. Sci., ser. A, 53(4) (2011) pp. 296-302.

The compositional heterogeneity of ethylene–1-hexene copolymers synthesized with various types of supported catalysts, namely, the titanium–magnesium catalyst TiCl4/MgCl2 and the zirconocene catalyst SiO2(MAO)/Me2Si(Ind)2ZrCl2, is studied via the method of successive self-nucleation–annealing (SSA) with the use of differential scanning calorimetry. On the basis of the data on the temperatures of individual peaks on SSA curves, the thickness of lamellas composed of macromolecules with a certain degree of short-chain branching is estimated. The copolymer synthesized with the zirconocene catalyst has a narrower range of fusion and does not contain large lamellas composed of molecules with a low degree of short-chain branching. With the use of the broadness index, it is shown that the copolymer synthesized with the zirconocene catalyst has a more uniform distribution of the comonomer than does the copolymer synthesized with the titanium–magnesium catalyst. For the copolymers synthesized with the titanium–magnesium catalyst, the compositional heterogeneity increases with an increase in the content of 1-hexene.

STATE OF TITANIUM IN SUPPORTED TITANIUM-MAGNESIUM CATALYSTS FOR PROPYLENE POLYMERIZATION

N.N. Chumachenko, G.D. Bukatov, S.A. Sergeev, V.A. Zakharov

Kinet. Catal., 52(2) (2011) pp. 234-241.

The oxidation state of titanium and the coordination state of Ti3+ ions in TiCl4/D1/MgCl2 (D1 is a phthalate) supported titanium-magnesium catalysts (TMCs) after the interaction with an AlEt3/D2 cocatalyst (D2 is propyltrimethoxysilane or dicyclopentyldimethoxysilane) were studied by chemical analysis and EPR spectroscopy. Different oxidation state distributions of titanium ions were observed in the activated catalyst and mother liquor: Ti3+ and Ti2+ ions were predominant in the activated catalyst and mother liquor, respectively. The effects of interaction conditions (reaction temperature and time and Al/Ti and D2/Ti molar ratios) of TMCs with the cocatalyst on the state of titanium in activated samples were studied. The interaction of TMCs with the cocatalyst decreased the titanium content and caused the appearance of aluminum in the activated sample, which was most clearly pronounced at a temperature of 25°C and occurred within the first 10 min of treatment. An increase in the temperature to 70°C and an increase in the interaction time to 60 min only slightly affected the concentrations of titanium and aluminum. The presence of D2 as a cocatalyst constituent facilitated the removal of titanium compounds and restricted the adsorption of aluminum compounds on the catalyst surface. The main fraction of titanium consisted of Ti3+ ions (62–89%), and the rest was Ti4+ ions (22–35%) under mild interaction conditions (25°C; Si/Ti = 25) or Ti4+ (0–21%) and Ti2+ (9–21%) ions under more severe conditions (50 or 70°C; Si/Ti from 0 to 5). According to EPR-spectroscopic data, at D2/Ti from 1 to 5, Ti3+ ions mainly occurred as associates, whereas they occurred as isolated ions at D2/Ti = 25. The initial and activated catalysts were similar in activity in the reaction of propylene polymerization, and titanium compounds, which were removed from the catalyst upon interaction with AlEt3/D2, were inactive in this process.

TITANIUM–MAGNESIUM CATALYSTS FOR PROPYLENE POLYMERIZATION: THE EFFECT OF DONORS

G.D. Bukatov, S.A. Sergeev, V.A. Zakharov, L.G. Echevskaya, M.A. Matsko

Catal. Ind., 3(2) (2011) pp. 103-108.

The chain transfer reaction with hydrogen at propylene polymerization over Ti–Mg catalysts (TMCs) of composition TiCl4/D1/MgCl2–AlEt3/D2 is studied in a wide hydrogen concentration range. A two-step mechanism of this reaction is suggested. This mechanism accounts for the fractional order of the reaction with respect to hydrogen concentration. Constants of chain transfer reaction with hydrogen are determined for TMC with different donors: 1,3-diether or dibutyl phthalate as D1 and tetraethoxysilane or dicyclopentyldimethoxysilane as D2. In propylene polymerization over the TMCs, the length of the polymer chain is mainly determined by the ratio of the propylene and hydrogen concentrations because the propagation and chain transfer rate constants are comparable. The rate constant of chain transfer with hydrogen at ethylene polymerization is significantly (more than one order of magnitude) less, and higher hydrogen concentrations are required for attaining the same degree of polymerization. The results of this study might be helpful in simulation of industrial polymerization processes and in control of the polymer molar mass.

COPOLYMERIZATION OF TETRAFLUOROETHYLENE WITH PERFLUORO(3,6-DIOXA-4-METHYL-7-OCTENE)SULFONYL FLUORIDE IN A WATER-EMULSION MEDIUM

S.S. Ivanchev, V.S. Likhomanov, O.N. Primachenko, S.Ya. Khaikin, V.G. Barabanov*, A.Yu. Men’shikova**, N.N. Shevchenko** (*Applied Chemistry Russian Scientific Center, St. Petersburg, Russia; **Institute of Macromolecular Compounds, St. Petersburg, Russia)

Doklady Chem., 437(1) (2011) pp. 66-68.

In the present work, based on the data on the kinetics of copolymerization of TFE and the sulfo-containing fluorinated monomer FS-141, it was demonstrated for the first time the possibility of realization of safe and efficient water-emulsion technology for producing a Nafion-type copolymer with satisfactory proton-conducting operational properties.

POLYMER HYDROGELS WITH THE MEMORY EFFECT FOR IMMOBILIZATION OF DRUGS

V.N. Pavlyuchenko*, S.S. Ivanchev, O.N. Primachenko, S.Ya. Khaikin, V.F. Danilichev*, V.S. Proshina*, V.A. Trunov**, V.T. Lebedev**, Yu.V. Kul'velis** (*Kirov Academy of Military Medicine, St. Petersburg, Russia; **Petersburg Nuclear Physics Institute, Gatchina, Leningrad oblast, Russia)

Polym. Sci., ser. A, 53(4) (2011) pp. 323-335.

Hydrogels with the memory effect are synthesized from crosslinked copolymers of 2-hydroxyethyl methacrylate and functional monomers (acrylic acid or dimethylaminoethyl methacrylate) via the method of template synthesis with the use of the drug cephazoline as a matrix. It is shown that the hydrogels show an increased sorption activity against the target drug and a slow rate of drug release from the hydrogel (the memory effect) under certain conditions. In combination with cephazoline, these hydrogels may be regarded as a new prolonged-drug-release system for the treatment of infectious diseases.

SMALL-ANGLE NEUTRON SCATTERING FROM POLYMER HYDROGELS WITH MEMORY EFFECT FOR MEDICINE IMMOBILIZATION

Yu.V. Kulvelis*, V.T. Lebedev*, V.A. Trunov*, V.N. Pavlyuchenko**, S.S. Ivanchev,

O.N. Primachenko, S.Ya. Khaikin (*Konstantinov Nuclear Physics Institute, Gatchina, Leningrad oblast, Russia; **Kirov Military Medical Academy, St. Petersburg, Russia)

Cryst. Rep., 56(7) (2011) pp. 1114-1117.

Hydrogels synthesized based on cross-linked copolymers of 2-hydroxyethyl methacrylate and functional monomers (acrylic acid or dimethylaminoethyl methacrylate), having a memory effect with respect to target medicine (cefazolin), have been investigated by small-angle neutron scattering. The hydrogels are found to have a two-level structural organization: large (up to 100 nm) aggregates filled with network cells (4–7 nm in size). The structural differences in the anionic, cationic, and amphiphilic hydrogels and the relationship between their structure and the ability of hydrogels to absorb moisture are shown. A relationship between the memory effect during cefazolin immobilization and the internal structure of hydrogels, depending on their composition and type of functional groups, is established.

BIOLIGAND CARRIERS BASED ON METHYL METHACRYLATE COPOLYMERS WITH N-VINYLFORMAMIDE OR GLYCIDYL METHACRYLATE

A.Yu. Men’shikova*, K.S. Inkin*, T.G. Evseeva*, Yu.O. Skurkis*, B.M. Shabsel’s*, N.N. Shevchenko*, S.S. Ivanchev (*Institute of Macromolecular Compounds, St. Petersburg, Russia)

Colloid J., 73(1) (2011) pp. 76-82.

Emulsifier-free emulsion copolymerization of methyl methacrylate with N-vinylformamide and glycidyl methacrylate initiated by a cationic or anionic azoinitiator in the presence of dextran is used to produce monodisperse polymer particles with a developed multifunctional surface. As a result, monodisperse particles are obtained with a diameter of 350–660 nm, the surface layer of which contains, in addition to carboxyl groups, amino or epoxy groups. The conditions are determined for the formation of multifunctional hydrophilic particle surface via the hydrolysis of comonomer units and residual groups of initiators. The limiting values of bovine serum albumin chemisorption (2.4 and 1.0 mg/m2 on the particles of methyl methacrylate copolymers with glycidyl methacrylate or N-vinyl formamide, respectively) indicate that the obtained particles have sufficient sorption capacity to be applied as carriers for immunoreagents.

POLYMER MEMBRANES FOR FUEL CELLS: ACHIEVEMENTS AND PROBLEMS

S.S. Ivanchev, S.V. Myakin

Carbon Nanomaterials in Clean Energy Hydrogen Systems – II, NATO Science for Peace and Security Series C: Environmental Security, Springer, Eds. S.Yu. Zaginaichenko, D.V. Schur,

V.V. Skorokhod, A. Veziroglu, B. Ibrahimoglu, 2011, V. 2, ch. 21, pp. 245-267.

The current state in the field of synthesis, structural modification and implementation of polymer membranes for fuel cells is analyzed. Synthetic methods, physicochemical characteristics and specific features of their composition, microphase separation and the structure of water ionic channels are considered for different types of proton-conducting materials together with the approaches to enhancement of their technical performances. The main focus is addressed to Nafion and other similar perfluorinated proton conducting polymer membranes as currently leading materials in respect of both R&D progress and commercial implementation in fuel cells of different purpose. The recent advances in submarine and automotive applications of Nafion based fuel cells are discussed.

SPECIFIC FEATURES OF ETHYLENE POLYMERIZATION ON SELF-IMMOBILIZING CATALYTIC SYSTEMS BASED ON TITANIUM bis(PHENOXY IMINE) COMPLEXES

N.I. Ivancheva, V.K. Badaev, E.V. Sviridova, D.A. Nikolaev, I.V. Oleinik*, S.S. Ivanchev

(*Vorozhtsov Institute of Organic Chemistry, Novosibirsk, Russia)

Russ. J. Appl. Chem., 84(1) (2011) pp. 118-123.

The kinetics of ethylene polymerization on six methylalumoxane-activated self-immobilizing

bis(phenoxy imine) complexes of titanium chloride with allyloxy groups in the m- and p-positions of the N-phenyl ring and with various substituents in the salicylaldehyde fragment was studied. The activity of the complexes in the temperature range 20–60°С and ethylene pressure of 0.4 MPa was evaluated.

EFFECT OF THE BASIC PROCESS PARAMETERS DURING POLYMERIZATION OF TETRAHYDROFURAN WITH PERCHLORIC ACID

A.E. Bal’tser*, V.M. Komarov*, A.G. Bazanov, N.G. Zubritskaya*, N.N. Machalaba** (*Applied Chemistry Russian Center, St. Petersburg, Russia; **Scientific-Research Institute of Synthetic Fibres, Tver, Russia)

Fiber Chem., 42(4) (2011) pp. 215-219.

Polymerization of tetrahydrofuran in the presence of the perchloric acid — acetic anhydride catalytic system evolves reversibly in time and is subjected to the strong effect of the temperature, where the yield and molecular weight of the oligomer decrease when the temperature increases. The molecular weight of the oligomer can be regulated by changing the amount of catalyst. It is most sensitive to a change in the amount of perchloric acid, which must be measured very precisely, while finer regulation can be performed by varying the amount of acetic anhydride.

THE INFLUENCE OF ADDITION OF LOW-MOLECULAR RUBBER ON PROPERTIES OF MIXTURES AND RUBBERS. II. MODIFICATION OF COMPOSITIONS BASED ON BUTADIENE-NITRILE RUBBER

D.V. Voronchikhin*, K.A. Dubkov, S.V. Semikolenov, D.P. Ivanov, I.A. Ilyin*

(*Siberian State Technological University, Novosibirsk, Russia)

Kauchuk & Rezina, 1 (2011) pp. 4-7.

The effect of modifying butadiene-nitrile rubber based polymer compositions with two oligobutadienes and a functional oligomer of new type – unsaturated polyketone (Mn=2200, 17.3 wt% of C=O groups) – on properties of the said composition was studied. The addition of polyketone was shown to improve technological behavior of the rubber mixture and characteristics of the vulcanizate.

ELASTOMER COMPOSITES CONTAINING PRODUCTS OF RUBBER RECLAIMING USING NITROGEN(I) OXIDE

D.V. Voronchikhin*, K.A. Dubkov, I.A. Ilyin*, M.A. Khudoley*, S.V. Semikolenov, D.P. Ivanov

(*Siberian State Technological University, Novosibirsk, Russia)

Kauchuk & Rezina, 5 (2011) pp. 33-35.

The influence of a regenerate obtained through treatment of rubber crumb with nitrogen suboxide on the properties of elastomer compositions was studied. The application of such a regenerate was shown to improve some parameters of rubber mixtures and vulcanizates.

Biocatalysts, Biochemical Phenomena, Biochemical Ecology

IMMOBILIZATION OF A RECOMBINANT STRAIN PRODUCING GLUCOSE ISOMERASE INSIDE SiO2-XEROGEL AND PROPERTIES OF PREPARED BIOCATALYSTS

G.A. Kovalenko, L.V. Perminova, T.V. Chuenko, L.I. Sapunova*, E.A. Shlyakhotko*, A.G. Lobanok* (*Institute of Microbiology, Minsk, Belarus)

Appl. Biochem. Microbiol., 47(2) (2011) pp. 151-157.

An original method of immobilization of non-growing microorganism cells inside xerogel of silicium dioxide containing insoluble hydroxyl compounds of cobalt(II) has been developed. A recombinant strain producing glucose isomerase has been constructed on the basis of Escherichia coli with the use of a gene of Arthrobacter nicotianae. It was revealed that glucose isomerase activity and stability of biocatalysts prepared on the basis of the recombinant E. coli strain was 3–5 times greater compared with the biocatalysts prepared with the use of the donor strain A. nicotianae. Under conditions of continuous hydrolysis of 3 M fructose at 62–65°C in a fixed bed reactor, time of half-inactivation of the biocatalysts prepared from the recombinant strain and A. nicotianae was∼60 and∼25 days, respectively.

Fe-EXCHANGED ZEOLITES AS MATERIALS FOR CATALYTIC WET PEROXIDE OXIDATION. DEGRADATION OF RODAMINE G DYE

R. Prihod’ko*, I. Stolyarova*, G. Gündüz**, O.P. Taran, S.A. Yashnik, V.N. Parmon, V. Goncharuk* (*Institute of Colloid and Water Chemistry, Kiev, Ukraine; **Ege University, Chemical Engineering Department, Izmir, Turkey)

Appl. Catal., B, 104(1-2) (2011) pp. 201-210.

The effect of surface acidity, nature, and dispersion of iron species, controlled by the catalyst preparation techniques and parent zeolite Si/Al ratio, on the catalytic wet peroxide oxidation of Rodamine G dye over the Fe-ZSM-5 materials has been studied.

Fe-ZSM-5 and Fe-USY have been prepared using two techniques: improved aqueous ion exchange (IE) and conventional aqueous ion exchange (CE). The former procedure causes some rearrangement of the coordination sphere of four-fold coordinated Al3+, accompanied by formation of a small amount of octahedrally coordinated non-framework aluminium species. In case of Fe-ZSM-5(IE), iron is predominantly present in the form of well-dispersed Fe2+ ions, while Fe-ZSM-5(CE) and Fe-USY(CE) contain small aggregated oligonuclear (FeO)n clusters formed by Fe3+. In both cases, iron species are mainly located inside the zeolite pore system. The contribution of the zeolite is a controlling factor in enhancing the Rhodamine G dye degradation activity of the Fe-ZSM-5 catalysts, which is influenced by the specific procedure used for preparation of these materials. The catalytic wet peroxide oxidation (CWPO) behaviours of the materials prepared via the (IE) and (CE) procedures differ due to different nature of the iron species involved. The non-framework Al3+ species present in both the Fe-exchanged ZSM-5 and USY zeolites may participate in formation of the active sites responsible for CWPO of Rhodamine G dye over these catalysts.

At near ambient temperature (323 K), quasi-neutral pH (4.9), short reaction time (around 150 min), catalyst concentration of 1.0 g L-1, and H2O2 addition rate of 41.2–82.3 mmol h-1, the (IE)-prepared Fe-ZSM-5 catalyst enables the total degradation of the dye, accompanied by removal of ca. 80% of TOC without notable leaching of the Fe ions.

GUAIACOL HYDRODEOXYGENATION IN THE PRESENCE OF Ni-CONTAINING CATALYSTS

M.V. Bykova, O.A. Bulavchenko, D.Yu. Ermakov, M.Yu. Lebedev, V.A. Yakovlev, V.N. Parmon

Catal. Ind., 3(1) (2011) pp. 15-22.

A series of Ni-containing catalysts supported on different materials has been tested in the hydrodeoxygenation of guaiacol, a compound modeling the products of biomass fast pyrolysis. The reaction has been carried out in an autoclave at 320°C and a hydrogen pressure of 17 MPa. The main guaiacol hydrodeoxygenation products are cyclohexane, 1-methylcyclohexane-1,2-diol, and cyclohexanone (which result from aromatic ring reduction). A guaiacol conversion scheme explaining the formation of the main products is suggested. The highest activity is shown by the Ni-containing catalysts on SiO2 and SiO2–ZrO2 supports prepared by the sol–gel method. According to X-ray diffraction and electron microscopic data, the high activity of these catalysts is due to the high concentration of dispersed nickel as reduced films on the surface of the silicate structures. The catalysts offer promise for refining the biomass fast pyrolysis products (bio-oil) into hydrocarbon fuel.

INVESTIGATION OF DIRECT HYDROCRACKING OF TRIGLYCERIDES OF FATTY ACIDS ON Ni-Cu/CeO2-ZrO2 CATALYST

S.A. Selishcheva, D.E. Babushkin, V.A. Yakovlev

Chem. Sustain. Devel., 19(2) (2011) pp. 187-193.

Catalytic hydrocracking of triglycerides of fatty acids of colza oil resulting in the formation of a mixture of С1219 alkanes was studied under mild conditions (0.5 MPa Н2, 300-380°C) over Ni-Cu/CeO2-ZrO2 catalyst. On the basis of the obtained distributions of hydrocracking products for different contact times and temperatures, a scheme of the stage-by-stage hydrocracking of triglycerides of fatty acids was proposed. It takes into account the formation of intermediate oxygenated products (fatty acids, esters, alcohols, wax).

THE MECHANISM OF INTERACTING BIOLOGICALLY ACTIVE COMPLEXES DEHYDROEPIANDROSTERONE OR TETRAHYDROCORTISOL -APOLIPOPROTEIN A-I WITH DNA AND THEIR ROLE IN ENHANCEMENT OF GENE EXPRESSION AND PROTEIN BIOSYNTHESIS IN HEPATOCYTES

L. Panin*, O. Gimautdinova*, P.A. Kuznetsov*, F.V. Tuzikov (*Research Institute of Biochemistry, Novosibirsk, Russia)

Curr. Chem. Biol., 5(5) (2011) pp. 9-16.

Dehydroepiandrosterone (DHEA), dehydroepiandrosterone-sulfate (DHEAS) and tetrahydrocortisol (THC) with apolipoprotein A-I form the biologically active complexes able to interact specifically with eukaryotic DNA. This conjugate is highly cooperative and results in local splitting of DNA. Specific binding sites of steroid-apoA-I complexes are the (GCC/GGC)n sequences. At the sites of splitting, single-stranded regions sensitized to the action of S1-nuclease form. These regions are irregularly distributed over DNA. The formation of single-stranded DNA regions can promote the interaction with RNA-polymerase. Formation of the biologically active THC (DHEA)-apoA-I complexes is related with resident macrophages having 5 α- and 5 β-reductase activity. These complexes greatly enhance the rate of protein biosynthesis in hepatocytes. The cortisol-apoA-I complex does not show such effect. So, the reduced forms of fascicular zone and reticular cortex adrenal zone hormones have synergism of action toward gene expression and protein biosynthesis. The intensification of tissues regeneration during the stress period as a result of given mechanism is discussed.

ECOLOGICAL AND MORPHOLOGICAL FEATURES OF NANO- AND MICROPARTICLES OF MINERALS OF ORAL ROUTES

K.S. Golokhvast*, N.N. Kiselev*, V.V. Chaika*, A.M. Panichev**, P.A. Nikiforov*, A.A. Vedyagin, I.V. Mishakov, I.E. Pamirskii***, A.N. Gulkov*

(*Far East State Technical University, Vladivostok, Russia; **Pacific Institute of Geography, Vladivostok, Russia; ***Institute of Geology and Natural Manegement, Blagoveshchensk, Russia)

Proceed. Samara Sci. Center RAS, 13(1(5)) (2011) pp. 1253-1255.

Results of studies of the effect of zeolites from Vanginsky, Lyulinsky, Kulikovsky and Kholinsky deposits on morphometric parameters of stomach and intestine cells of mouse Mus muscuus are represented. It is shown that Nanoparticles from all 5 fields of zeolites taken in the experiment, at a dosage of 3-5% of body weight and ranging from 100 nm to 1 micron are toxic.

ECOTOXICOLOGY OF NANO- AND MICROPARTICLES

K.S. Golokhvast*, A.M. Panichev**, I.V. Mishakov, A.A. Vedyagin, M.S. Melgunov, M.M. Danilova, S.G. Kozlova***, S.P. Gabuda***, N.K. Moroz***, M.S. Melgunov, N.N. Kiselev*, V.V. Chaika*, A.N. Gulkov* (*Far East State Technical University, Vladivostok, Russia; **Pacific Institute of Geography, Vladivostok, Russia; ***Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Proceed. Samara Sci. Center RAS, 13 (1(5)) (2011) pp. 1256-1259.

Approaches to studying inorganic water insoluble materials toxicity – nano- and microparticles of natural minerals are considered. Possible reasons and mechanism of various biological effects of the last are discussed.

CURRENT APPROACHES TO DEVELOPMENT OF CONTRAST AGENTS FOR MRI DIAGNOSTICS

K.N. Sorokina, A.A. Tulupov*, T.G. Tolstikova**, V.Yu. Ussov*** (*International Tomography Center, Novosibirsk, Russia; **Vorozhtsov Institute of Organic Chemistry, Novosibirsk, Russia; ***Tomsk Institute of Cardiology, Tomsk, Russia)

Bull. Siberian Med., 6 (2011) pp. 79-86.

Magnetic resonance imaging (MRI) is primarily used in medical imaging to visualize the structure and function of the body and essential tool for diagnostics of broad range of pathologies. But still in a growing number of cases there are indications to use contrast agent to delineate areas of interest and for more precise diagnosis definition. In a review the properties and clinical applications of most popular paramagnetic contrast agents based on Gd(III), Fe(II) и Mn(II) are discussed. It is also focused on discussion of modern experimental targeted contrast agents (conjugates of antibodies, nanoparticles and dendrimers) and advances of their application for early diagnostics of most common pathologies: cardiovascular, cancer and Alzheimer diseases.

PHYSICOCHEMICAL EXOMETABOLITE PROCESSING FOR CLOSED LIFE SUPPORT SYSTEMS

E.F. Sutormina, S.V. Trifonov*, Yu.A. Kudenko*, Yu.A. Ivanova, L.G. Pinaeva, A.A. Tikhomirov*, L.A. Isupova (*Institute of Biophysics, Krasnoyarsk, Russia)

Chem. Sustain. Devel., 19(4) (2011) pp. 413-420.

Composition of gas mixtures formed during the electrochemical (in the presence of H2O2) oxidation of the wastes of human vital activities and subsequent decomposition of carbamide remaining in solution after the oxidation of metabolites was studied. The principal possibility of catalytic selective oxidation of ammonia evolved in the decomposition of carbamide to form nitrogen oxides was demonstrated, for the purpose of obtaining the salts of nitric acid that are well assimilated by plants.

Catalysis in Organic Synthesis

NEW METHOD OF DIMETHYL SULFIDE SYNTHESIS

A.V. Mashkina

Russ. J. Org. Chem., 47(5) (2011) pp. 678-681.

The synthesis of dimethyl sulfide consists in the reaction of dimethyl disulfide with methanol in the presence of solid catalyst, aluminum γ-oxide. The yield of dimethyl sulfide grows with growing temperature, contact time, and content of methanol in the reaction mixture. At 350-400°C, molar ratio methanol-dimethyldisulfide 2.0-2.5, and total conversion of the reagents the yield of dimethyl sulfide reached 95 mol%.

A CATALYTIC PROCESS FOR PREPARATION OF THIOPHENE FROM FURAN AND HYDROGEN SULFIDE

A.V. Mashkina

Russ. J. Appl. Chem., 84(7) (2011) pp. 1223-1228.

Thiophene formation under various conditions from furan and Н2S in the presence of γ-Al2O3, both unpromoted and promoted with transition metal oxides, was examined. The conditions enabling preparation of thiophene in a 95–98 mol% yield were determined.

INVESTIGATION OF THE MECHANISM OF CATALYTIC RECYCLIZATION OF FURAN TO THIOPHENE

A.V. Mashkina

Chem. Heterocycl. Compd., 9 (2010) pp. 1063-1067.

Investigation of the formation of thiophene from furan and hydrogen sulfide at various catalysts showed that the activity of the catalysts increases with increase in the strength and concentration of Lewis acid centers. It was found by IR spectroscopy that if the degree of coverage of the aluminum oxide surface with hydrogen sulfide is higher than monolayer its dissociative chemisorption does not occur. Mechanism was postulated which assume that the reaction takes place through stage with the formation of a surface intermediate, including coordination of the α-carbon atoms of the furan ring with the Lewis acid center and with the sulfur atom of molecular hydrogen sulfide.

EPOXIDATION OF BUTADIENE WITH HYDROGEN PEROXIDE CATALYZED BY THE SALTS OF PHOSPHOTUNGSTATE ANIONS: RELATION BETWEEN CATALYTIC ACTIVITY AND COMPOSITION OF INTERMEDIATE PEROXO COMPLEXES

L.I. Kuznetsova, N.I. Kuznetsova, R.I. Maksimovskaya, G.I. Aleshina, O.S. Koscheeva*, V.A. Utkin (*Nikolaev Institute of Inorganic Chemistry, Novosibirsk, Russia)

Catal. Lett., 141(10) (2011) pp. 1442-1450.

Epoxidation of 1,3-butadiene has been studied in acetonitrile solutions of aqueous H2O2 and tetrabutylammonium or 1-ethyl-3-methylimidazolium salts of phosphotungstate anions:

[(n-C4H9)4N]3{PO4[WO(O2)2]4}, [(n-C4H9)4N]5Na0.6H1.4[PW11O39] or [(C2H5)(CH3)C3H3N2]5NaH[PW11O39]. The selectivity of the 1,3-butadiene to 3,4-epoxy-1-butene (EpB) conversion attains 97% at nearly 100% efficiency of the H2O2 consumption. The rate of the EpB formation has been correlated with the solution compositions as found by 31P NMR under the reaction conditions.

Bis[3-(3,5-DIALKYL-4-HYDROXYPHENYL)PROPYL]MONO- AND DISULFIDES AS THE SEVILEN STABILIZERS

A.P. Krysin*, T.B. Khlebnikova (*Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk, Russia)

Russ. J. Gen. Chem., 81(6) (2011) pp. 1159-1162.

The effect of the shielding degree of the phenol hydroxy group on the hydrolytic and thermal stability of ethylene-vinyl acetate copolymer (Sevilen) was studied on a series of phenols containing one or two sulfur atoms in the aliphatic chain of the para-substituent. Among the synthesized compounds a group of disulfides was found with a high antioxidant efficiency, which increase the Sevilen hydrolytic stability. The most effective are the 6-tert-butyl-2-methylphenol derivatives.

NEW APPROACH TO THE SYNTHESIS OF tris(PERFLUOROALKYL)BORANE ADDUCTS WITH DIALKYLAMINES

N.Yu. Adonin, V.V. Bardin*, U. Florke**, H.-J. Fron*** (*Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk, Russia; **Paderborn University, Germany; ***Duisburg-Essen University, Germany)

Russ. J. Gen. Chem., 81(3) (2011) pp. 509-516.

A convenient synthetic approach to the adducts (CnF2n+1)3BNHR2 (n = 2–4, 6; R = Me, Et) was developed, based on the reaction of lithium perfluoroalkyls with dichloro(dialkylamino)boranes at temperatures below –90°C. The target products can be synthesized with preparative yields of 50–90%.

MECHANISTIC INSIGHTS INTO OXIDATION OF 2-METHYL-1-NAPHTHOL WITH DIOXYGEN: AUTOXIDATION OR A SPIN-FORBIDDEN REACTION?

O.A. Kholdeeva, I.D. Ivanchikova, O.V. Zalomaeva, A.B. Sorokin*, I.Y. Skobelev, E.P. Talsi (*Institut de Recherches sur la Catalyse, Villeurbanne Cedex, France)

J. Phys. Chem. B, 115(42) (2011) pp. 11971–11983.

Oxidation of 2-methyl-1-naphthol (MNL) with molecular oxygen proceeds efficiently under mild reaction conditions (3 atm O2, 60–80°C) in the absence of any catalyst or sensitizer and produces 2-methyl-1,4-naphthoquinone (MNQ, menadione, or vitamin K3) with selectivity up to 80% in nonpolar solvents. 1H NMR and 1H,1H-COSY studies revealed the formation of 2-methyl-4-hydroperoxynaphthalene-1(4H)-one (HP) during the reaction course. Several mechanistic hypotheses, including conventional radical autoxidation, electron transfer mechanisms, photooxygenation, and thermal intersystem crossing (ISC), have been evaluated using spectroscopic, mass-spectrometric, spin-trapping, 18O2 labeling, kinetic, and computational techniques. Several facts collectively implicate that ISC contributes significantly into MNL oxidation with O2 at elevated pressure: (i) the reaction rate is unaffected by light; (ii) C–C-coupling dimers are practically absent; (iii) the reaction is first order in both MNL and O2; (iv) the observed activation parameters (ΔH = 8.1 kcal mol–1 and ΔS = -50 eu) are similar to those found for the spin-forbidden oxidation of helianthrene with 3O2 (Seip, M.; Brauer, H.-D.J. Am. Chem. Soc.1992, 114, 4486); and (v) the external heavy atom effect (2-fold increase of the reaction rate in iodobenzene) points to spin inversion in the rate-limiting step.

SYNTHESIS OF A NEW OPTICALLY PURE CHIRAL DIAMINE FROM LEVOPIMARIC ACID

V.N. Konev, T.B. Khlebnikova, Z.P. Pai

Chem. Sustain. Devel., 19(2) (2011) pp. 165-168.

Synthesis of a new chiral optically pure diamine of diterpene series was carried out on the basis of the components of available natural renewable raw material. The resulting tricyclic trans-1,2-diamine and its derivatives can be used as the ligands in metal complex catalysts of asymmetrical reactions.

MEERWEIN–PONNDORF–VERLEY REDUCTION OF ALDEHYDES FORMED in situ FROM α- AND β-PINENE EPOXIDES IN A SUPERCRITICAL FLUID IN THE PRESENCE OF ALUMINA

V. Il`ina*, S.Yu. Kurbakova*, K.P. Volcho*, N.F. Salakhutdinov*, V.I. Anikeev (*Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk, Russia)

J. Saudi Chem. Soc., 15(4) (2011) pp. 313-317.

The use of a system consisting of flow-type reactor, supercritical fluid containing isopropanol/CO2 and alumina as a catalyst allows the one-pot isomerization of α- and β-pinene epoxides into campholenic aldehyde and myrtanal and Meerwein– Ponndorf–Verley reduction of these aldehydes to the corresponding alcohols.

REARRANGEMENTS OF VERBENOL EPOXIDE IN SUPERCRITICAL FLUIDS

K.P. Volcho*, I.V. Il`ina*, N.F. Salakhutdinov*, V.I. Anikeev (*Vorozhtsov Novosibirsk Institute of Organic Chemistry, Novosibirsk, Russia)

ARKIVOC, 8 (2011) pp. 134-140.

Transformations of verbenol epoxide in a supercritical mixture of CO2, isopropyl alcohol, and water were studied. The main identified products were similar to those obtained in the presence of Montmorillonite clays, but with much shorter contact times and without an acid catalyst. The reactivity of verbenol epoxide in supercritical media differs dramatically from the behavior of this epoxide in the presence of Lewis acid ZnBr2. In contrast to studies of α-pinene epoxide transformations, the presence of water caused no essential changes in product distribution. The presence of triethylamine suppressed the rearrangements; obviously the reaction has cationic character.

STEP CHANGES AND DEACTIVATION BEHAVIOR IN THE CONTINUOUS DECARBOXYLATION OF STEARIC ACID

A.Th. Madsen*,**, B. Rozmyszowicz**, I.L. Simakova, T. Kilpiö**, A.-R. Leino***, K. Kordás***, K. Eränen**, P. Mäki-Arvela**, D.Yu. Murzin** (*Technical University of Denmark, Lyngby, Denmark; **Abo Akademi University, Turku, Finland; ***University of Oulu, Oulu, Finland)

Ind. Eng. Chem. Res., 50(19) (2011) pp. 11049–11058.

Deoxygenation of dilute and concentrated stearic acid over 2% Pd/C beads was performed in a continuous reactor at 300°C and 20 bar pressure of Ar or 5% H2/Ar. Stable operation was obtained in 5% H2 atmosphere, with 95% conversion of 10 mol % dilute stearic acid in dodecane and 12% conversion of pure stearic acid. Deactivation took place in H2-deficient gas atmosphere, probably as a result of the formation of unsaturated products and coking in the pore system. Transient experiments with step changes were performed: 1 h was required for the step change to be visible in liquid sampling, whereas steady states were achieved after a total of 2.5–3 h. Postreaction analysis of the spent catalyst revealed that a deactivation profile was formed downward over the catalyst bed.

THE CHEMISTRY OF 2,3-DIHYDROISOXAZOLE DERIVATIVES

N.V. Chukanov, V.A. Reznikov* (*Vorozhtsov Institute of Organic Chemistry, Novosibirsk, Russia)

Russ. Chem. Bull., 60(3) (2011) pp. 379-399.

Methods for the synthesis and transformations of 2,3-dihydroisoxazole derivatives are reviewed. Data on reduction and oxidation reactions and intramolecular rearrangements are generalized; their mechanisms are discussed.

Mathematical Simulation, Calculating Models

EVALUATION OF GOLD ON ALUMINA CATALYST DEACTIVATION DYNAMICS DURING α-PINENE ISOMERIZATION

Yu.S. Solkina, S.I. Reshetnikov, M. Estrada*, A.V. Simakov**, D.Yu. Murzin***, I.L. Simakova

(*Posgrado de Fisica de Materiales de CICESE-UNAM, Ensenada, B.C., Mexico; **Universidad Nacional Autonoma de Mexico, Ensenada, B.C., Mexico; ***Abo Akademi University, PCC, Turku/Abo, Finland)

Chem. Eng. J., 176-177 (2011) pp. 42-48.

Synthesis of camphene is an important step in an industrial process for camphor production from α-pinene. Compared to conventional way of α-pinene to camphene transformation over acid-hydrated TiO2, gold on alumina catalyst was found to provide α-pinene isomerization conversion up to 99.9% and selectivity 60–80% making this catalyst very promising from an industrial viewpoint. However, deactivation of gold catalyst might be a serious obstacle for real industrial implementation. According to TPO and UV–vis-mass in situ it was shown that deactivation is caused by adsorption of hydrocarbons on the gold species. The dynamics of catalyst deactivation during α-pinene isomerization was presented based on a so-called “separable” deactivation model assumption. Effects of isomerization temperature, initial α-pinene concentration and gas atmosphere on catalyst deactivation with time-on-stream were investigated experimentally and correlated with the proposed deactivation function. The results showed that the α-pinene concentration was the major factor governing the deactivation of Au/γ-Al2O3 catalyst under substrate-feeding conditions. When the α-pinene concentration was controlled at a relatively low level such as 0.4 vol.%, especially in hydrogen atmosphere, the total deactivation rate was negligible. An equation of the reaction rate taking into account the catalyst deactivation was suggested making prediction of deactivation behavior in α-pinene conversion at different initial concentrations.

INFLUENCE OF CLUSTER SIZE DISTRIBUTION ON CLUSTER SIZE DEPENDENT CATALYTIC KINETICS

D.Yu. Murzin*, I.L. Simakova (*Åbo Akademi University, Turku, Finland)

Catal. Lett., 141(7) (2011) pp. 982-986.

A theoretical analysis of the influence of particle size distribution on observed TOF dependence on cluster size is presented for a two step catalytic cycle. Such mechanism can display different TOF behavior including maxima. In the later case simulations demonstrated broadening of TOF curves compared to an idealized case of very narrow PSD. However, for more often observed cases with smooth TOF increase or decrease with cluster size increase incorporation of particle size distribution in kinetic analysis is not required at least for often experimentally observed particle size distributions.

THERMODYNAMIC ANALYSIS OF THE CLUSTER SIZE EVOLUTION IN CATALYST PREPARATION BY DEPOSITION–PRECIPITATION

D.Yu. Murzin*, O.A. Simakova, I.L. Simakova, V.N. Parmon (*Åbo Akademi University, Turku, Finland)

React. Kinet. Mech. Catal., 104(2) (2011) pp. 259-266.

Several gold catalysts supported on various inorganic supports with different point zero charge (pzc) were prepared by deposition–precipitation with urea (DPU). A thermodynamic model accounting for cluster evolution was advanced. The key element in the model is the dependence of the interfacial energy on the relative approach to pzc during DP. Experimental data were compared with the model, showing a possibility to utilize the theoretical approach to predict the cluster size.

MODELING AND CALCULATION OF THE PROCESS OF RAPID EXPANSION OF SUPERCRITICAL FLUID YIELDING NANOPARTICLES

V.I. Anikeev, D.A. Stepanov, An. Yermakova

Theor. Found. Chem. Eng., 45(2) (2011) pp. 141-155.

A mathematical model is proposed and the calculation is carried out for the process of rapid expansion of the supercritical fluid containing a dissolved solid compound via a capillary into a volume with specified temperature and pressure. The analysis of sensitivity of the model toward the process parameters makes it possible to choose the most important parameters for producing nanoparticles with preset properties and dimensions. The calculations demonstrate that all the parameters of the expansion process under study have a particular effect on the size of the particles being formed.

PHASE AND CHEMICAL EQUILIBRIA IN THE TRANSESTERIFICATION REACTION OF VEGETABLE OILS WITH SUPERCRITICAL LOWER ALCOHOLS

V.I. Anikeev, D.A. Stepanov, An. Yermakova

Russ. J. Phys. Chem. A, 85(8) (2011) pp. 1336-1346.

Calculations of thermodynamic data are performed for fatty acid triglycerides, free fatty acids, and fatty acid methyl esters, participants of the transesterification reaction of vegetable oils that occurs in methanol. Using the obtained thermodynamic parameters, the phase diagrams for the reaction mixture are constructed, and the chemical equilibria of the esterification reaction of free fatty acids and the transesterification reaction of fatty acid triglycerides attained upon treatment with supercritical methanol are determined. Relying on the analysis of the obtained equilibria for the esterification reaction of fatty acids and the transesterification reaction of triglycerides attained upon treatment with lower alcohols, the authors select the optimum conditions for performing the reaction in practice.

CALCULATING THE THERMODYNAMIC CHARACTERISTICS OF THE STEPWISE TRANSESTERIFICATION OF SIMPLE TRIGLYCERIDES

V.I. Anikeev, D.A. Stepanov, An. Yermakova

Russ. J. Phys. Chem. A, 85(12) (2011) pp. 2082-2087.

Thermodynamic data for mono- and diglycerides of palmitic, oleic, and linoleic fatty acids participating in the stepwise transesterification reaction of the corresponding simple triglycerides in methanol are calculated. The obtained thermodynamic parameters allow to calculate the chemical equilibrium and the equilibrium composition of the products of the stepwise transesterification reaction of fatty acid triglycerides with supercritical methanol.

CALCULATIONS OF PHASE EQUILIBRIA FOR MIXTURES OF TRIGLYCERIDES, FATTY ACIDS, AND THEIR ESTERS IN LOWER ALCOHOLS

D.A. Stepanov, An. Yermakova, V.I. Anikeev

Russ. J. Phys. Chem. A, 85(1) (2011) pp. 21-25.

The objects of study were mixtures containing triglycerides and lower alcohols and also the products of the transesterification of triglycerides, glycerol and fatty acid esters. The Redlich-Kwong-Soave equation of state was used as a thermodynamic model for the phase state of the selected mixtures over wide temperature, pressure, and composition ranges. Group methods were applied to determine the critical parameters of pure substances and their acentric factors. The parameters obtained were used to calculate the phase diagrams and critical parameters of mixtures containing triglycerides and lower alcohols and the products of the transesterification of triglycerides, glycerol and fatty acid esters, at various alcohol/oil ratios. The conditions of triglyceride transesterification in various lower alcohols providing the supercritical state of reaction mixtures were selected.

 

REACTION REVERSIBILITY IN α-PINENE THERMAL ISOMERIZATION: IMPROVING THE KINETIC MODEL

A.M. Chibiryaev*, An. Yermakova, I.V. Kozhevnikov (Worozhtsov Institute of Organic Chemistry, Novosibirsk, Russia)

Russ. J. Phys. Chem. A, 85(8) (2011) pp. 1347-1357.

Revision of the experimental data on a-pinene thermal isomerization attained in supercritical ethanol allowed to expand the reaction scheme, which includes now six main products and eleven reversible reactions. The equilibrium constants of every reaction (KT,- and КФ, ) were calculated to allow for reversibility of reactions. The thermochemical data of the pure compounds required to calculate constants KTj- and K<S>j (standard enthalpy and entropy of formation AfH (298.15 K), AfS (298.15 K), heat capacity CP(T), critical parameters Tcr and pcr, boiling point Тb, and the acentric factor со) were preliminary estimated using the empirical Joback and Benson methods. A kinetic model based on the new expanded scheme of reversible reactions was successfully identified and its kinetic parameters kj (600 K) and Ej were determined. Detailed examination of the new kinetic model allowed us to refine the generally accepted mechanism of a-pinene thermal isomerization and to distinguish additional features of the multistep process.

ACTIVATION PARAMETERS OF SUPERCRITICAL AND GAS-PHASE β-PINENE THERMAL ISOMERIZATION

A.M. Chibiryaev*, An. Yermakova,I.V. Kozhevnikov (*Worozhtsov Institute of Organic Chemistry, Novosibirsk, Russia)

Russ. J. Phys. Chem. A, 85(9) (2011) pp. 1505-1515.

New data on enthalpy and entropy contributions to the energy barrier of p-pinene thermal isomerization were obtained. The rate of P-pinene conversion is higher in supercritical EtOH (P = 120 atm) than in the gas phase (P < 1 atm, without solvent, or for inert carrier gas N2) at equal temperatures. The highest activation energy Еъ of total P-pinene conversion is also observed in reactions in the supercritical (sc) condition. Activation parameters AH-/, AS/, and AG-/ depend strongly on the reaction pressure. Thus, at P < 1 atm (gas-phase reaction) the values of AS"/ are negative, while at sc conditions at P = 120 atm is positive. The linear dependences lnfe0 ~ Ey. and AS"/ - AS"/ indicate an isokinetic relation (IKR) and enthalpy-entropy compensation effect (EEC). The isokinetic temperature was calculated (Tiso = 605.5 ± 22.7 K). It was shown that elevation of temperature reduces the value of AG/(7) upon sc thermolysis only, whereas in all gas-phase reactions AG/(7) increases. At equal reaction temperatures, the greatest values of Keq#(T) proved to be typical for thermolysis in sc-EtOH. It was hypothesized that the rate of total p-pinene conversion increases dramatically due to a considerable shift in equilibrium toward higher concentrations of activated complex >-TS#. A detailed analysis of activation parameters shows that the IKR and EEC coincide, evidence of a common mechanism of p-pinene conversion observed under different reaction conditions, including thermolysis in sc-EtOH.

MATHEMATICAL MODELING OF β-PICOLINE OXIDATION TO NICOTINIC ACID IN MULTITUBULAR REACTOR: EFFECT OF THE GAS RECYCLE

E.V. Ovchinnikova, N.V. Vernikovskaya, T.V. Andrushkevich, V.A. Chumachenko

Chem. Eng. J., 176-177 (2011) pp. 114-123.

Mathematical modeling of nicotinic acid synthesis process by means of p-picoline air oxidation in multitubular reactor was carried out. Factors that impact the process efficiency were studied. Special attention was focused on the role of recycling. The analysis was based on a two-dimensional quasi-homogeneous mathematical model of a tubular reactor and proprietary kinetic model of p-picoline oxidation over V2O5-TiO2 catalyst.

MATHEMATICAL MODELING OF THE PROPANE DEHYDROGENATION PROCESS IN THE CATALYTIC MEMBRANE REACTOR

E.V. Shelepova, A.A. Vedyagin, I.V. Mishakov, A.S. Noskov

Chem. Eng. J., 176-177 (2011) pp. 151-157.

The two-dimensional non-isothermal stationary mathematical model of the catalytic membrane reactor for the process of propane dehydrogenation has been developed. The made calculations have shown the higher efficiency of the membrane reactor in comparison with the tubular one which is achieved due to removal of hydrogen from reactionary zone through the membrane to shift the reaction equilibrium towards formation of products. The use of membrane was found to cause the propane conversion increase from 41% to 67%. The highest value of propane conversion (X = 96%) was reached in case of additional oxidation of the removed hydrogen (conjugated dehydrogenation). The maximum value of propylene selectivity S = 98% can be as well reached in case of conjugated dehydrogenation in the membrane reactor at the reaction temperature of 500°C. The oxidation of hydrogen in conjugated dehydrogenation process gives the increase of propylene yield from 65% (the tubular reactor) to 95%. The maximum propylene yield corresponds to T = 525°C. It was also established that the gas space velocity in both internal and external parts of the membrane reactor is to be the one of the most important factors defining efficiency of the conjugated dehydrogenation process.

EFFECT OF CATALYTIC COMBUSTION OF HYDROGEN ON THE DEHYDROGENATION PROCESSES IN A MEMBRANE REACTOR. I. MATHEMATICAL MODEL OF THE PROCESS

E.V. Shelepova, A.A. Vedyagin, A.S. Noskov

Combust. Explos. Shock Waves, 47(5) (2011) pp. 499-507.

Mathematical modeling of a catalytic membrane reactor was performed for thermodynamically coupled processes using as an example the endothermic dehydrogenation of propane and the exothermic combustion (oxidation) of hydrogen. Benefits of using the membrane reactor to increase the yield of target products by shifting equilibrium was demonstrated theoretically. The effect of hydrogen combustion on the main characteristics of the endothermic dehydrogenation process was studied. The hydrogen combustion reaction makes it possible to further increase the conversion of propane and compensate for the energy consumption in the endothermic dehydrogenation process.

VARIATIONAL PRINCIPLES IN IRREVERSIBLE THERMODYNAMICS WITH APPLICATION TO COMBUSTION WAVES

A.P. Gerasev

J. Non-Equilib. Thermodyn., 36(1) (2011) pp. 55-73.

The thermodynamics of physicochemical processes in a reacting distributed kinetic system are considered, and the entropy balance equation for traveling waves of laminar combustion is derived for arbitrary Lewis number. Qualitative and numerical analysis of a dynamic system with a three-dimensional phase space and of the local and complete entropy production in the system were performed. It is shown that the complete entropy production in the system is a functional of the traveling wave solution of the problem, possessing extreme properties, whose minimum corresponds to the only physically meaningful traveling wave solution. The procedure of “cut-off” (zeroing) of the reaction rate is justified by methods of non-equilibrium thermodynamics. A variational formulation of the problem is presented for calculation of a steady laminar combustion wave.

SIMULATION OF CATALYTIC PROCESSES IN A FIXED BED WITH THE USE OF MICROWAVE RADIATION FOR PERFORMING AN ENDOTHERMIC REACTION

A.P. Gerasev

Kinet. Catal., 52(6) (2011) pp. 907-913.

A quasi-homogeneous model of a catalytic fixed-bed reactor, in which an endothermic chemical reaction occurs with the use of microwave radiation energy, was proposed and numerically analyzed. The versions of the arrangement of a radiation source at the reactor inlet and outlet and also the versions of microwave radiation energy conversion into heat by a catalyst and an initial gaseous reagent were considered. The effects of model parameters on the dynamic behavior of the system were studied, and a qualitative structural difference between the resulting steady-state conditions was demonstrated. The phenomenon of endothermic chemical reaction autowave propagation was discovered, and the regularities of this propagation were studied.

DISTRIBUTION OF CATALYTIC, FILTRATIONAL AND HYBRID AUTOWAVES IN THE HETEROGENEOUS ENVIRONMENT

A.P. Gerasev

Chem. Ind. Today, 1 (2011) pp. 6-12.

Mathematical modeling of autowave heterogeneous processes with chemical reactions in a gas phase and on the catalyst is carried out. Values of factors of interphase heat– and masstransfer and heat conductivity of a solid phase were defined on current values of parameters of system. Qualitative distinction of structure of three kinds of autowaves is shown: filtrational burning of gases in a mode of low speeds, with catalytic reaction and hybrid autowaves with simultaneously going reactions in a gas phase and on the catalyst. Numerical modelling of the system on the basic technological indicators of autowave process is performed.

KINETICS STUDY OF THE PERCHLOROETHYLENE HYDROFLUORINATION INTO PENTAFLUOROETHANE (FREON 125) OVER CHROMIUM-BASED CATALYST

S.I. Reshetnikov, A.A. Zirka, R.V. Petrov, E.A. Ivanov

Chem. Eng. J., 176-177 (2011) pp. 22-25.

The gas-phase hydrofluorination of perchloroethylene (PCE) into pentafluoroethane (non ozonedepleting Freon 125) at T = 330–390°C and P = 0.4 MPa in the presence of a chromium– magnesium catalyst has been studied. A hydrofluorination scheme including main product and by-products formation routes is deduced from the observed dependences of particular products selectivity. The kinetic model of the PCE hydrofluorination has been developed. The rate parameters and the activation energy of the reactions were determined. The model satisfactorily describes the experimental data in the temperature range 330–390°C.

EFFECT OF THE MOBILITY OF OXYGEN IN PEROVSKITE CATALYST ON THE DYNAMICS OF OXIDATIVE COUPLING OF METHANE

S.I. Reshetnikov, Yu.I. Pyatnitskii*,

L.Yu. Dolgikh* (*L.V. Pisarzhevskii Institute of Physical Chemistry, Kyiv, Ukraine)

Theor. Exp. Chem., 47(1) (2011) pp. 49-54.

The effect of the diffusion of oxygen from the volume of the catalyst to its surface on the dynamics of the oxidative coupling of methane was assessed on the basis of a mathematical model of the reaction of methane with the oxidized surface of KNaSrCoO3-x perovskite. It was shown that the possible values of the diffusion coefficient lie in the range of 10-18-10-16 cm2/s characteristic of the diffusion of oxygen in oxide catalysts.

THE STABILITY OF AN ISOTHERMAL GASEOUS SPHERE WITH GRAVITATION

V.N. Snytnikov, O.A. Stadnichenko

Astron. Rep., 55(3) (2011) pp. 214-223.

A dispersion relation has been obtained for waves propagating in an inhomogeneous gas with viscosity and gravity in the direction of the density gradient. It has been shown that a stationary distribution of isothermal gas is unstable under gravitational-convective perturbations. It is suggested that the initial- and boundary-value problems of the non-stationary dynamics of an isothermal gas with gravity but without viscosity are incorrect and require regularization, for example, by adding viscosity. The presence of viscosity does not prevent the development of the Jeans long-wave instability. Numerical experiments based on a fully three-dimensional, non-stationary numerical code have demonstrated the development of a collapse inside an isothermal cloud.

EFFECT OF WATER ON OXIDATIVE SCISSION OF 1-BUTENE TO ACETIC ACID OVER V2O5-TiO2 CATALYST. TRANSIENT ISOTOPIC AND KINETIC STUDY

W. Suprun*, E.M. Sadovskaya, Ch. Rüdinger**, H.-J. Eberle**, M. Lutecki*, H. Papp*

(*Universität Leipzig, Leipzig, Germany; **Wacker Chemie AG, Consortium für Elektrochemische Industrie GmbH, München, Germany)

Appl. Catal. A, 391(1-2) (2011) pp. 125-136.

The role of water in the oxidation of 1-butene to AcOH over VOx-TiO2 was investigated using spectroscopic and transient isotopic exchange methods. It was shown that the influence of water strongly depended on the temperature of reaction. In particular, DRIFTS and NH3-TPD studies confirmed the temperature influence on the acidity and the amount of adsorbed water. XPS investigations suggested that not only oxygen from vanadia, but also from the lattice of titania was involved in the oxygen transfer during the reaction. Formation of oxidation products proceeded over two types of active vanadium oxide centers, i.e., VOH and VO. Hydrated vanadium species exhibited high selectivity towards AcOH formation. On the other hand, VO centers favored total oxidation. Kinetic model was developed for an unambiguous interpretation of the experimental results. Modelled reaction constants of the formation of AcOH over VOH centers were ca. 3.5 times higher than over VO centers. At the same time, the reaction rate constant of total oxidation in the presence of water was ca. 3.2 times lower than in dry flow. Estimated values suggested that in the presence of water the number of VOH centers was substantially lower than VO sites; however their contribution to the rate of AcOH formation was much higher.

INVESTIGATION OF MASS TRANSFER ON GLASS FABRIC CATALYST DURING CO OXIDATION REACTION

О.V. Chub, А.S. Noskov, L.G. Simonova

Chem. Ind. Today, 5 (2011) pp. 19-24.

The mass transfer during CO oxidation reaction has been investigated using Pd-containing catalyst prepared on the basis of glass fabrics of various weaves. The mathematical model of experimental reactor is formulated. The results are shown in the form of criterial dependency Sh = A Ren Sc1/3, mass transfer coefficients and equation parameters have been determined.

ON А LIMIT EQUATIONS AND ATTRACTION FOR NONAUTONOMOUS SYSTEMS WITH DELAY

I.A. Finogenko*, N.A. Chumakova (*Institute for System Dynamics and Control Theory, Irkutsk, Russia)

Tambov University Reports. Ser.: Nat. Techn. Sci., 16(5) (2011) pp. 1247-1253.

For nonautonomous functional-differential equations property of quasiinvariance for limiting sets and analogue of the La-Salle principle of invariancy by use of Lyapunov functional with constant sign derivative is established.

COMPUTATIONAL FLUID DYNAMICS IN THE DESIGN OF CATALYTIC REACTORS

O.P. Klenov, A.S. Noskov

Catal. Ind., 3(4) (2011) pp. 331-349.

Computational fluid dynamics is becoming an important tool in the study of chemical engineering processes and apparatuses (in particular, the share of works with the application of this method is nearly 6% of the total number of all chemical engineering works issued by Elsevier Science Publishers in 2010). The possibilities of computational fluid dynamics are demonstrated using examples from three different chemical engineering fields: developing a method for loading a tubular reactor for the steam conversion of natural gas, studying heat transfer in a reactor for the hydrogenation of vegetable oils upon the replacement of a catalyst, and investigating the transitional processes in an automobile neutralizer. The results from computational fluid dynamics are verified by comparing them with experimental data in developing a method for loading a tubular reactor, using the problem of decelerating a catalyst particle with a flow of air as an example. The obtained data are compared with classical measurement data on the aerodynamic drag of a ball and a cylinder and represent the further development of works on the flow around particles of complex shape. In this work, the results from inspecting a reactor for the hydrogenation of oils with allowance for the possible heating and uniform distribution of a flow before its entering the catalyst bed are presented. It is shown that the construction of the reactor does not ensure homogeneity of the reaction flow at the desired level and requires modification of heating elements. The efficiency of computational fluid dynamics for investigating fast processes with a chemical reaction is exemplified by studying the transitional processes in an catalytic automobile neutralizer (the effect of flow dynamics and heat transfer on the thermal regime in a honeycomb catalyst particle is very difficult to study by experimental methods). The application of computational fluid dynamics allows us to reduce considerably the time and cost of developing and optimizing the designs of efficient catalytic fixed-, fluidized-, or moving-bed reactors (particularly multiphase stirred (slurry) reactors), along with mixers, adsorbers, bubblers, and other chemical engineering apparatuses with moving media.

SOLID DISPERSION IN THE SLURRY REACTOR WITH MULTIPLE IMPELLERS

O.P. Klenov, A.S. Noskov

Chem. Eng. J., 176-177 (2011) pp. 75-82.

A whole series of significant catalytic processes are carried out in a slurry reactor with multiple impellers. The selective hydrogenation of sunflower seed oil is the characteristic example of such a process. The liquid phase is the main medium into stirred tank and an investigation of a fluid dynamics of one just as transient regime of solid distribution in liquid volume could be helpful to practical application.

In the present work, CFD simulations have been carried out to study solid distribution in liquid–solid stirred tank using Mixture multifluid approach along with standard k-ε turbulence model. A multiple frame of reference (MFR) and Sliding Mesh Model have been used to model the multiple impellers and tank region. The effects of specific density of fine-dispersed solid phase and place of injection of solid have been investigated for “steady-state” and time-depended cases.

 

MODELING DESIGN AND ANALYSIS OF MULTI-LAYER SOLID OXIDE FUEL CELLS

R. Hasanov*, A. Smirnova**, A. Gulgazli*, M. Kazimov*, A. Volkov*, V. Quliyeva*, O. Vasylyev***, V.A. Sadykov (*Azerbaijan State Oil Academy, Baku, Azerbaijan; **Eastern Connecticut State University, Willimantic, USA; ***Institute for Problems of Materials Science, Kiev, Ukraine)

Int. J. Hydrogen Energy, 36(2) (2011) pp. 1671-1682.

The thermo-mechanical analytical model proposed for different solid oxide fuel cell (SOFC) designs addresses the deformation behavior and mechanical stability of SOFCs at various thermal stresses, specifically the creep resistance and the long-term endurance beyond the elastic limit.

The model considers the deformation of multi-layer SOFC in the temperature range of 600–800°C and presents the combination of the correlated parameters for SOFC performance evaluation, stability and long-term endurance under realistic operating conditions and temperature gradients. The numerical analysis of the thermo-mechanical properties of the SOFC materials is presented in terms of mechanical behavior at failure conditions and the influence of rheological and structural properties on SOFC long-term endurance. The SOFC thermal behavior, creep parameters of the SOFC materials and long-term stability are analyzed in terms of stresses, deformations and displacements.

In terms of broader impact, the algorithms for Maurice-Levi and Voltaire theorems and their validity for non-elastic, e.g. viscous-elastic, viscous-plastic, and elastic-plastic deformations were confirmed. This result allowed to apply the stress condition of non-elastic body to the stress condition of the elastic body which is relevant to the SOFC operation at elevated temperatures.

ETHYLENE GLYCOL OXIDATION OVER SUPPORTED CATALYST IN TUBULAR REACTOR

M.A. Salaev*, A.A. Krejker*, O.V. Magaev*, V.S. Malkov*, A.S. Knyazev*, E.S. Borisova, V.M. Khanaev, O.V. Vodyankina*, L.N. Kurina*

(*Tomsk State University, Tomsk, Russia)

Chem. Eng. J., 172(1) (2011) pp. 399-409.

Macrokinetics for chemical transformation of ethylene glycol into glyoxal (including side-reactions) as well as 2D heterogeneous mathematical model were suggested. Numerical results obtained using this model were compared with the experimental data obtained at lab-scale and pilot reactor, and showed good correlation. It was shown that due to catalyst activity change it is possible to manage the process selectivity with respect to glyoxal in diffusion mode. The optimal value of catalyst activity providing the highest process selectivity can be found.

SIMULATION OF HETEROGENEOUS CATALYTIC REACTION BY ASYNCHRONOUS CELLULAR AUTOMATA ON MULTICOMPUTER

A.E. Sharifulina*, V.I. Elokhin (*Institute of Computational Mathematics and Mathematical Geophysics, Novosibirsk, Russia)

Lecture Notes Comput. Sci., 6873 (2011) pp. 204-209.

In the paper parallel implementation of ACA simulating dynamics of carbon monoxide oxidation over the Pd(100) is presented. Parallel implementation of ACA is based on its approximation by block-synchronous CA. To estimate approximation accuracy comparative analysis of statistical characteristics and bifurcation diagrams, obtained by ACA and BCSA simulation, is performed. Results of parallel implementation of BSCA algorithm and estimations of its efficiency are presented.

Fuel Chemistry and Technology

DEACTIVATION AND OXIDATIVE REGENERATION OF MODERN CATALYSTS FOR DEEP HYDROPURIFICATION OF DIESEL FUEL: OXIDATIVE REGENERATION OF IC-GO-1 CATALYST

S.V. Budukva, O.V. Klimov, G.S. Litvak, Yu.A. Chesalov, I.P. Prosvirin, T.V. Larina, A.S. Noskov

Russ. J. Appl. Chem., 84(1) (2011) pp. 95-102.

Oxidative regeneration of a deactivated IC-GO-1 catalyst was studied in removal of carbonaceous deposits and sulfur from the catalyst composition. Elemental analysis data, texture characteristics, and catalytic activities of fresh and regenerated samples were compared. Raman spectroscopy, X-ray phase analysis, electronic diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy were used to examine the structure of cobalt and molybdenum compounds entering into the composition of the catalysts.

HYDROCRACKING OF VACUUM GAS OIL IN THE PRESENCE OF SUPPORTED NICKEL–TUNGSTEN CATALYSTS

A.S. Ivanova, E.V. Korneeva, G.A. Bukhtiyarova, A.L. Nuzhdin, A.A. Budneva, I.P. Prosvirin, V.I. Zaikovsky, A.S. Noskov

Kinet. Catal., 52(3) (2011) pp. 446-458.

The supports containing 70% Al2O3 and 30% β zeolite (AZ-1 and AZ-2), which differed in mixing procedures, and the Ni-W/AZ-1 and Ni-W/AZ-2 catalysts were characterized using an adsorption technique, high-resolution electron microscopy, IR spectroscopy, and X-ray photoelectron spectroscopy and tested in the hydrocracking reaction of vacuum gas oil (VGO). It was found that the supports differed in texture characteristics and surface Lewis acidity at the same composition and similar concentrations of Brønsted acid sites. The formation of Ni-W-S sulfide species on the surfaces of both of the supports occurred in different manners: multilayer Ni-W-S sulfide species were formed on AZ-1 (Ssp = 220 m2/g), whereas single-layer species were mainly formed on AZ-2 (Ssp = 380 m2/g). It was found that catalysts containing multilayer Ni-W-S sulfide species, which were characterized by a higher degree of sulfidation, provided a higher yield of diesel fuel upon the hydrocracking of VGO, whereas catalysts containing single-layer Ni-W-S sulfide species were more active in the reactions of VGO hydrodesulfurization and hydrodenitration.

EFFECT OF THE MOBILITY OF OXYGEN IN PEROVSKITE CATALYST ON THE DYNAMICS OF OXIDATIVE COUPLING OF METHANE

S.I. Reshetnikov, Yu.I. Pyatnitskii*, L.Yu. Dolgikh* (*L.V. Pisarzhevskii Institute of Physical Chemistry, Kyiv, Ukraine)

Theor. Exp. Chem., 47(1) (2011) pp. 49-54.

The effect of the diffusion of oxygen from the volume of the catalyst to its surface on the dynamics of the oxidative coupling of methane was assessed on the basis of a mathematical model of the reaction of methane with the oxidized surface of KNaSrCoO3-x perovskite. It was shown that the possible values of the diffusion coefficient lie in the range of 10-18-10-16 cm2/s characteristic of the diffusion of oxygen in oxide catalysts.

THE STABILITY OF AN ISOTHERMAL GASEOUS SPHERE WITH GRAVITATION

V.N. Snytnikov, O.A. Stadnichenko

Astron. Rep., 55(3) (2011) pp. 214-223.

A dispersion relation has been obtained for waves propagating in an inhomogeneous gas with viscosity and gravity in the direction of the density gradient. It has been shown that a stationary distribution of isothermal gas is unstable under gravitational-convective perturbations. It is suggested that the initial- and boundary-value problems of the non-stationary dynamics of an isothermal gas with gravity but without viscosity are incorrect and require regularization, for example, by adding viscosity. The presence of viscosity does not prevent the development of the Jeans long-wave instability. Numerical experiments based on a fully three-dimensional, non-stationary numerical code have demonstrated the development of a collapse inside an isothermal cloud.

EFFECT OF WATER ON OXIDATIVE SCISSION OF 1-BUTENE TO ACETIC ACID OVER V2O5-TiO2 CATALYST. TRANSIENT ISOTOPIC AND KINETIC STUDY

W. Suprun*, E.M. Sadovskaya, Ch. Rüdinger**, H.-J. Eberle**, M. Lutecki*, H. Papp*

(*Universität Leipzig, Leipzig, Germany; **Wacker Chemie AG, Consortium für Elektrochemische Industrie GmbH, München, Germany)

Appl. Catal. A, 391(1-2) (2011) pp. 125-136.

The role of water in the oxidation of 1-butene to AcOH over VOx-TiO2 was investigated using spectroscopic and transient isotopic exchange methods. It was shown that the influence of water strongly depended on the temperature of reaction. In particular, DRIFTS and NH3-TPD studies confirmed the temperature influence on the acidity and the amount of adsorbed water. XPS investigations suggested that not only oxygen from vanadia, but also from the lattice of titania was involved in the oxygen transfer during the reaction. Formation of oxidation products proceeded over two types of active vanadium oxide centers, i.e., VOH and VO. Hydrated vanadium species exhibited high selectivity towards AcOH formation. On the other hand, VO centers favored total oxidation. Kinetic model was developed for an unambiguous interpretation of the experimental results. Modelled reaction constants of the formation of AcOH over VOH centers were ca. 3.5 times higher than over VO centers. At the same time, the reaction rate constant of total oxidation in the presence of water was ca. 3.2 times lower than in dry flow. Estimated values suggested that in the presence of water the number of VOH centers was substantially lower than VO sites; however their contribution to the rate of AcOH formation was much higher.

INVESTIGATION OF MASS TRANSFER ON GLASS FABRIC CATALYST DURING CO OXIDATION REACTION

О.V. Chub, А.S. Noskov, L.G. Simonova

Chem. Ind. Today, 5 (2011) pp. 19-24.

The mass transfer during CO oxidation reaction has been investigated using Pd-containing catalyst prepared on the basis of glass fabrics of various weaves. The mathematical model of experimental

reactor is formulated. The results are shown in the form of criterial dependency Sh = A Ren Sc1/3, mass transfer coefficients and equation parameters have been determined.

ON А LIMIT EQUATIONS AND ATTRACTION FOR NONAUTONOMOUS SYSTEMS WITH DELAY

I.A. Finogenko*, N.A. Chumakova (*Institute for System Dynamics and Control Theory, Irkutsk, Russia)

Tambov University Reports. Ser.: Nat. Techn. Sci., 16(5) (2011) pp. 1247-1253.

For nonautonomous functional-differential equations property of quasiinvariance for limiting sets and analogue of the La-Salle principle of invariancy by use of Lyapunov functional with constant sign derivative is established.

COMPUTATIONAL FLUID DYNAMICS IN THE DESIGN OF CATALYTIC REACTORS

O.P. Klenov, A.S. Noskov

Catal. Ind., 3(4) (2011) pp. 331-349.

Computational fluid dynamics is becoming an important tool in the study of chemical engineering processes and apparatuses (in particular, the share of works with the application of this method is nearly 6% of the total number of all chemical engineering works issued by Elsevier Science Publishers in 2010). The possibilities of computational fluid dynamics are demonstrated using examples from three different chemical engineering fields: developing a method for loading a tubular reactor for the steam conversion of natural gas, studying heat transfer in a reactor for the hydrogenation of vegetable oils upon the replacement of a catalyst, and investigating the transitional processes in an automobile neutralizer. The results from computational fluid dynamics are verified by comparing them with experimental data in developing a method for loading a tubular reactor, using the problem of decelerating a catalyst particle with a flow of air as an example. The obtained data are compared with classical measurement data on the aerodynamic drag of a ball and a cylinder and represent the further development of works on the flow around particles of complex shape. In this work, the results from inspecting a reactor for the hydrogenation of oils with allowance for the possible heating and uniform distribution of a flow before its entering the catalyst bed are presented. It is shown that the construction of the reactor does not ensure homogeneity of the reaction flow at the desired level and requires modification of heating elements. The efficiency of computational fluid dynamics for investigating fast processes with a chemical reaction is exemplified by studying the transitional processes in an catalytic automobile neutralizer (the effect of flow dynamics and heat transfer on the thermal regime in a honeycomb catalyst particle is very difficult to study by experimental methods). The application of computational fluid dynamics allows us to reduce considerably the time and cost of developing and optimizing the designs of efficient catalytic fixed-, fluidized-, or moving-bed reactors (particularly multiphase stirred (slurry) reactors), along with mixers, adsorbers, bubblers, and other chemical engineering apparatuses with moving media.

SOLID DISPERSION IN THE SLURRY REACTOR WITH MULTIPLE IMPELLERS

O.P. Klenov, A.S. Noskov

Chem. Eng. J., 176-177 (2011) pp. 75-82.

A whole series of significant catalytic processes are carried out in a slurry reactor with multiple impellers. The selective hydrogenation of sunflower seed oil is the characteristic example of such a process. The liquid phase is the main medium into stirred tank and an investigation of a fluid dynamics of one just as transient regime of solid distribution in liquid volume could be helpful to practical application.

In the present work, CFD simulations have been carried out to study solid distribution in liquid–solid stirred tank using Mixture multifluid approach along with standard k-ε turbulence model. A multiple frame of reference (MFR) and Sliding Mesh Model have been used to model the multiple impellers and tank region. The effects of specific density of fine-dispersed solid phase and place of injection of solid have been investigated for “steady-state” and time-depended cases.

MODELING DESIGN AND ANALYSIS OF MULTI-LAYER SOLID OXIDE FUEL CELLS

R. Hasanov*, A. Smirnova**, A. Gulgazli*, M. Kazimov*, A. Volkov*, V. Quliyeva*, O. Vasylyev***, V.A. Sadykov (*Azerbaijan State Oil Academy, Baku, Azerbaijan; **Eastern Connecticut State University, Willimantic, USA; ***Institute for Problems of Materials Science, Kiev, Ukraine)

Int. J. Hydrogen Energy, 36(2) (2011) pp. 1671-1682.

The thermo-mechanical analytical model proposed for different solid oxide fuel cell (SOFC) designs addresses the deformation behavior and mechanical stability of SOFCs at various thermal stresses, specifically the creep resistance and the long-term endurance beyond the elastic limit.

The model considers the deformation of multi-layer SOFC in the temperature range of 600–800°C and presents the combination of the correlated parameters for SOFC performance evaluation, stability and long-term endurance under realistic operating conditions and temperature gradients. The numerical analysis of the thermo-mechanical properties of the SOFC materials is presented in terms of mechanical behavior at failure conditions and the influence of rheological and structural properties on SOFC long-term endurance. The SOFC thermal behavior, creep parameters of the SOFC materials and long-term stability are analyzed in terms of stresses, deformations and displacements.

In terms of broader impact, the algorithms for Maurice-Levi and Voltaire theorems and their validity for non-elastic, e.g. viscous-elastic, viscous-plastic, and elastic-plastic deformations were confirmed. This result allowed to apply the stress condition of non-elastic body to the stress condition of the elastic body which is relevant to the SOFC operation at elevated temperatures.

ETHYLENE GLYCOL OXIDATION OVER SUPPORTED CATALYST IN TUBULAR REACTOR

M.A. Salaev*, A.A. Krejker*, O.V. Magaev*, V.S. Malkov*, A.S. Knyazev*, E.S. Borisova, V.M. Khanaev, O.V. Vodyankina*, L.N. Kurina*

(*Tomsk State University, Tomsk, Russia)

Chem. Eng. J., 172(1) (2011) pp. 399-409.

Macrokinetics for chemical transformation of ethylene glycol into glyoxal (including side-reactions) as well as 2D heterogeneous mathematical model were suggested. Numerical results obtained using this model were compared with the experimental data obtained at lab-scale and pilot reactor, and showed good correlation. It was shown that due to catalyst activity change it is possible to manage the process selectivity with respect to glyoxal in diffusion mode. The optimal value of catalyst activity providing the highest process selectivity can be found.

SIMULATION OF HETEROGENEOUS CATALYTIC REACTION BY ASYNCHRONOUS CELLULAR AUTOMATA ON MULTICOMPUTER

A.E. Sharifulina*, V.I. Elokhin (*Institute of Computational Mathematics and Mathematical Geophysics, Novosibirsk, Russia)

Lecture Notes Comput. Sci., 6873 (2011) pp. 204-209.

In the paper parallel implementation of ACA simulating dynamics of carbon monoxide oxidation over the Pd(100) is presented. Parallel implementation of ACA is based on its approximation by block-synchronous CA. To estimate approximation accuracy comparative analysis of statistical characteristics and bifurcation diagrams, obtained by ACA and BCSA simulation, is performed. Results of parallel implementation of BSCA algorithm and estimations of its efficiency are presented.

Fuel Chemistry and Technology

DEACTIVATION AND OXIDATIVE REGENERATION OF MODERN CATALYSTS FOR DEEP HYDROPURIFICATION OF DIESEL FUEL: OXIDATIVE REGENERATION OF IC-GO-1 CATALYST

S.V. Budukva, O.V. Klimov, G.S. Litvak, Yu.A. Chesalov, I.P. Prosvirin, T.V. Larina, A.S. Noskov

Russ. J. Appl. Chem., 84(1) (2011) pp. 95-102.

Oxidative regeneration of a deactivated IC-GO-1 catalyst was studied in removal of carbonaceous deposits and sulfur from the catalyst composition. Elemental analysis data, texture characteristics, and catalytic activities of fresh and regenerated samples were compared. Raman spectroscopy, X-ray phase analysis, electronic diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy were used to examine the structure of cobalt and molybdenum compounds entering into the composition of the catalysts.

HYDROCRACKING OF VACUUM GAS OIL IN THE PRESENCE OF SUPPORTED NICKEL–TUNGSTEN CATALYSTS

A.S. Ivanova, E.V. Korneeva, G.A. Bukhtiyarova, A.L. Nuzhdin, A.A. Budneva, I.P. Prosvirin, V.I. Zaikovsky, A.S. Noskov

Kinet. Catal., 52(3) (2011) pp. 446-458.

The supports containing 70% Al2O3 and 30% β zeolite (AZ-1 and AZ-2), which differed in mixing procedures, and the Ni-W/AZ-1 and Ni-W/AZ-2 catalysts were characterized using an adsorption technique, high-resolution electron microscopy, IR spectroscopy, and X-ray photoelectron spectroscopy and tested in the hydrocracking reaction of vacuum gas oil (VGO). It was found that the supports differed in texture characteristics and surface Lewis acidity at the same composition and similar concentrations of Brønsted acid sites. The formation of Ni-W-S sulfide species on the surfaces of both of the supports occurred in different manners: multilayer Ni-W-S sulfide species were formed on AZ-1 (Ssp = 220 m2/g), whereas single-layer species were mainly formed on AZ-2 (Ssp = 380 m2/g). It was found that catalysts containing multilayer Ni-W-S sulfide species, which were characterized by a higher degree of sulfidation, provided a higher yield of diesel fuel upon the hydrocracking of VGO, whereas catalysts containing single-layer Ni-W-S sulfide species were more active in the reactions of VGO hydrodesulfurization and hydrodenitration.

CATALYTIC DEOXYGENATION OF TALL OIL FATTY ACIDS OVER A PALLADIUM-MESOPOROUS CARBON CATALYST: A NEW SOURCE OF BIOFUELS

P. Mäki-Arvela*, B. Rozmysłowicz**, S. Lestari***, O.A. Simakova, K. Eränen*, T. Salmi*, D.Yu. Murzin* (*Åbo Akademi University, Turku, Finland; **Poznan University of Technology, Poznan, Poland; ***University of Queensland, Brisbane, Queensland, Australia)

Energy Fuels, 25(7) (2011) pp. 2815-2825.

Catalytic deoxygenation of tall oil fatty acids (TOFAs) was investigated over 1 wt% Pd/C Sibunit, which is a synthetic mesoporous carbon. The reactions were performed in a semi-batch reactor using dodecane as a solvent under 17 bar of total pressure. The main studied parameters were the reaction temperature, initial concentration of TOFA, effect of the reaction atmosphere, and metal loading. The temperature and initial concentration ranges were 300-350°C and 0.15-0.6 mol/L, respectively. The total conversion of fatty acids increased, as expected, with increasing temperatures and decreasing initial TOFA concentrations. The main liquid-phase products were n-heptadecane and n-heptadecene. In addition to the desired linear C17 hydrocarbons, also aromatic C17 compounds, such as undecylbenzene, were formed. The best conditions for the formation of the desired C17 hydrocarbons were lower initial concentrations of TOFA, 300-325°C, and the presence of hydrogen. An increase of the metal loading (4 wt%) led to an increase of the selectivity to linear C17 hydrocarbons.

CATALYTIC DEOXYGENATION OF C18 FATTY ACIDS OVER MESOPOROUS Pd/C CATALYST FOR SYNTHESIS OF BIOFUELS

I.L. Simakova, B. Rozmysłowicz*, O.A. Simakova, P. Mäki-Arvela*, A. Simakov**, D.Yu. Murzin*

(*Abo Akademi University, Turku, Finland; **Centro de Nanociencias y Nanotecnología, UNAM, Ensenada, BC, México)

Top. Catal., 54(8-9) (2011) pp. 460-466.

Deoxygenation was systematically investigated using either stearic, oleic or linoleic acids as a feedstock at 300°C under 1 vol% hydrogen in argon over a mesoporous Pd/C (Sibunit) catalyst producing one less carbon containing, diesel-like hydrocarbons.

The results revealed that catalyst activity and selectivity increased with less unsaturated feedstock. The main products in the case of stearic acid were desired C17 hydrocarbons, whereas the amounts of C17 aromatic compounds increased in case of oleic and linoleic acids. Catalyst deactivation was relatively prominent in linoleic acid deoxygenation giving only 3% conversion of fatty acids in 330 min. The deactivation originated from the formation of C17 aromatic compounds and fatty acid dimers, which was confirmed by size exclusion chromatographic analysis. The latter compounds were formed via Diels-Alder reaction.

CATALYSIS IN BIOMASS PROCESSING

D.Yu. Murzin*, I.L. Simakova (*Åbo Akademi University, Turku, Finland)

Catal. Ind., 3(3) (2011) pp. 218-249.

Biomass has in recent years been considered as a raw material for the production of fuels and chemicals. This work discusses the reasons for the increased interest in mainly lignocellulosic biomass. Gasification, pyrolysis, and depolymerization by hydrolysis are analyzed as key biomass technology. The authors also discuss which of the sugars obtained via depolymerization by hydrolysis can be processed into fuel or key intermediates of the chemical industry. Lignocellulosic biomass contains such extractants as fatty acids and terpenes, and the authors therefore describe the catalytic reactions of these substances for the synthesis of fuels and chemicals. Some typical reactions of biomass processing (oxidation, hydrogenation, cracking, etc.) are conceptually close to the process widely known in the refining and chemical industries. There are, however, other considerations due to, e.g., the large number of functional (hydroxyl and other) groups, and the processing of biomass components therefore requires dehydration, aldol condensation, ketonization, decarboxylation, etc. The authors cover the fundamentals of the approaches to selecting catalysts for these reactions.

METHANE CONVERSION TO VALUABLE CHEMICALS OVER NANOSTRUCTURED Mo/ZSM-5 CATALYSTS

Z.R. Ismagilov, E.V. Matus, M.A. Kerzhentsev, L.T. Tsykoza, I.Z. Ismagilov, K.D. Dosumov*, A.G. Mustafin** (*Sokol’skii Institute of Organic Catalysis and Electrochemistry, Almaty, Republic of Kazakhstan; **Bashkir State University, Ufa, Russia)

Pet. Chem., 51(3) (2011) pp. 174-186.

Results of the ongoing study of nonoxidative methane dehydroaromatization (DHA) over Mo/ZSM-5 catalysts have been analyzed. The effects of the composition, preparation procedure, pretreatment, and the CH4 DHA reaction conditions on the physicochemical and catalytic properties of Mo/ZSM-5 catalysts have been discussed. The data on Mo-containing active sites, the methane DHA reaction mechanism, and the nature of carbonaceous deposits have been considered. The principal causes of the deactivation of Mo/ZSM-5 catalysts and means of their regeneration have been revealed. Approaches to the improvement of the methane DHA process and trends of its further development have been detailed.

OXIDATIVE DESULFURIZATION OF HYDROCARBON FUELS

Z.R. Ismagilov, S.A. Yashnik, M.A. Kerzhentsev, V.N. Parmon, A. Bourane*, F.M. Al-Shahrani*, A.A. Hajji*, O.R. Koseoglu* (*Saudi Aramco, Research and Development Center, Dhahran, Kingdom of Saudi Arabia)

Catal. Rev. - Sci. Eng., 53(3) 2011) pp. 199-255.

New requirements for very low sulfur content (10 ppm) in liquid motor fuels demand novel approaches for ultra-deep desulfurization. For production of near-zero-sulfur diesel and low-sulfur fuel oil, removal of refractory sulfur compounds, like 4,6-dimethyldibenzothiophene and other alkyl-substituted thiophene derivatives, is necessary. Elimination of these compounds by hydrodesulfurization (HDS) requires high hydrogen consumption, high pressure equipment, and new catalysts. Various oxidative desulfurization processes, including recent advances in this field for diesel fuels, and the drawbacks of this technology in comparison with HDS are examined and discussed. It is shown that the oxidation of sulfur compounds to sulfones with hydrogen peroxide allows for production of diesel fuels with a sulfur content of 10 ppmw or lower at atmospheric pressure and room temperature. The gas phase oxidative desulfurization of sulfur compounds with air or oxygen is feasible at atmospheric pressure and higher temperatures: 90–300°С and offers better economic solutions and incentives.

CARBON DIOXIDE REFORMING OF METHANE OVER Со-Ni CATALYSTS

G.B. Aldashukurova*, A.V. Mironenko*, Z.A. Mansurov*, N.V. Shikina, S.A. Yashnik, Z.R. Ismagilov (*Institute for Problems of Combustion, Almaty, Kazakhstan)

Chem. Eng. Trans., 25 (2011) pp. 63-68.

Low-percentage catalysts for dry reforming of methane (DRM) with Ni and Co deposited on a glass fiber support by the “solution combustion” (SC) method have been developed. Particle size and state of the active component were studied by XRD, TPR, TEM, SEM and AFM. The active component was shown to be dispersed in the near-surface layer of support as nanoparticles of size 10–20 nm, which have a Co3O4 or (Co,Ni)Co2O4 spinel structure depending on the catalyst composition. Spinel structure of the active component is resistant to carbonization and provides high catalytic activity toward DRM.

HETEROGENEOUS CATALYSTS FOR THE TRANSFORMATION OF FATTY ACID TRIGLYCERIDES AND THEIR DERIVATIVES TO FUEL HYDROCARBONS

V.A. Yakovlev, S.A. Khromova, V.I. Bukhtiyarov

Russ. Chem. Rev., 80(10) (2011) pp. 911-925.

The results of studies devoted to the catalysts for transformation of fatty acid triglycerides and their derivatives to fuel hydrocarbons are presented and described systematically. Various approaches to the use of heterogeneous catalysts for the production of biofuel from these raw materials are considered. The bibliography includes 134 references.

PYROLYSIS OF RAPIDLY GROWING GRASS BIOMASS UNDER ISOTHERMAL CONDITIONS

S.G. Zavarukhin, I.A. Streltsov, V.A. Yakovlev

Kinet. Catal., 52(4) (2011) pp. 499-505.

The pyrolysis of rapidly growing grass biomass in an inert atmosphere was studied by thermogravimetric analysis using sorghum as an example. Pyrolysis was performed under isothermal conditions at temperatures from 250 to 400°C. To describe the reaction kinetics, a single-component model including six first-order reactions was proposed. A special feature of this model is the occurrence of a step of the formation of an intermediate carbonaceous substance from the volatile products of biomass decomposition

PRODUCTION OF BIODIESEL FORM RAPESEED OIL USING HETEROGENEOUS Ba-Al CATALYST IN THREE-PHASE REACTOR

S.G. Zavarukhin, M.Yu. Lebedev, A.N. Simonov, L.G. Matvienko, A.S. Ivanova, V.N. Parmon, V.G. Sister*, O.V. Sherstyuk, M.V. Bukhtiyarova, V.A. Yakovlev (*Moscow State University of Ecological Engineering)

Chem. Ind. Today, 10 (2011) pp. 14-22.

The production of biodiesel by transesterification of rapeseed oil using methanol and heterogeneous BaAl catalyst was studied in three-phase reactor. Simplified kinetic model of transesterification process was proposed and the catalyst volume was calculated for the industrial reactor with the performance 2250 kg/hour of oil with oil conversion 95 %.

POROUS NICKEL BASED CATALYSTS FOR PARTIAL OXIDATION OF METHANE TO SYNTHESIS GAS

V.A. Kirillov, Z.A. Fedorova, M.M. Danilova, V.I. Zaikovsky, N.A. Kuzin, V.A. Kuzmin, T.A. Krieger, V.D. Meshcheryakov

Appl. Catal. A, 401(1-2) (2011) pp. 170-175.

The phase composition and texture of nickel catalysts supported on ribbon porous nickel with a magnesium oxide underlayer were investigated by X-ray diffraction, low-temperature nitrogen adsorption, and electron microscopy combined with energy dispersive X-ray microanalysis. The MgO underlayer was obtained by impregnation the porous nickel with a Mg(NO3)2 solution followed by calcination at 550°C; nickel was supported additionally by impregnation with a Ni(NO3)2 solution followed by calcination at 450°C. In the supported reduced nickel catalysts (800-900°C, H2) the phases of Ni and a solid solution of NiO in MgO were observed; a considerable part of nickel crystallites was epitaxially bound with MgO. The partial oxidation of methane to synthesis gas (800°C, O2/C = 0.65, GHSV = 127 L/g h) over porous nickel based catalysts was studied. The activity of initial nickel support decreased considerably during the partial oxidation of methane; the value of methane conversion decreased slightly after 100 h of testing on the supported nickel catalysts.

Chemical Engineering

EFFECT OF INTERNAL DIFFUSION ON PREFERENTIAL CO OXIDATION IN A HYDROGEN-RICH MIXTURE ON A COPPER-CERIUM OXIDE CATALYST IN A MICROCHANNEL REACTOR

D.I. Potemkin, P.V. Snytnikov, V.D. Belyaev, V.A. Sobyanin

Kinet. Catal., 52(1) (2011) pp. 139-144.

The effect of internal diffusion on preferential CO oxidation in a hydrogen-rich mixture on a copper-cerium catalyst in a microchannel reactor was estimated. It was found that the internal effectiveness factor ηCO > 0.8 was reached at a catalytic coating thickness of ∼30 μm.

PREFERENTIAL CO OXIDATION OVER Cu/CeO2x CATALYST: INTERNAL MASS TRANSPORT LIMITATION

D.I. Potemkin, P.V. Snytnikov, V.D. Belyaev, V.A. Sobyanin

Chem. Eng. J., 176-177 (2011) pp. 165-171.

The effect of internal mass transport limitation on the preferential CO oxidation in hydrogen-rich mixture over copper-cerium oxide catalyst in a form of pellets and washcoat in microchannel reactor is estimated. Internal effectiveness factor r|CO >0.8 in the optimum interval of reaction temperature (170-230°C) is reached if the pellet diameter and washcoat thickness do not exceed 100 and 20 цm, respectively.

Compared to conventional packed-bed reactor with catalyst pellets, microchannel catalytic washcoated reactor is more appropriate for practical use.

TECHNIQUE FOR COMPLETE OXIDATION OF ORGANIC COMPOUNDS IN SUPERCRITICAL WATER

V.I. Anikeev, An. Yermakova

Russ. J. Appl. Chem., 84(1) (2011) pp. 88-94.

Results are presented of tests of a pilot stationary installation for supercritical water oxidation of organic compounds, first created in Russia. A high oxidation efficiency of nitro compounds formed as waste in manufacture of explosives is demonstrated.

APPLICATION OF SYNTHESIS GAS AS A FUEL ADDITIVE ONBOARD THE VEHICLE: STATE OF THE ART AND PROSPECTS

V.N. Parmon, V.A. Kirillov, V.A. Sobyanin, V.A. Burtsev*, V.K. Emel’yanov**, N.A. Kuzin, V.V. Kireenkov, Yu.I. Amosov

(*OOO Gasomotor-R, Rybinsk, Yaroslavl oblast, Russia; **International Science and Technology Center, Moscow, Russia)

Theor. Found. Chem. Eng., 45(2) (2011) pp. 127-140.

A method for the production of a hydrogen-rich gas on board a vehicle was suggested and driving- and bench-tested for application in studies on energy-efficient internal combustion engines with minimum CO, CO2, CH, and NOx emissions. The generated gas is further added to the main fuel fed to the engine. Catalysts for hydrocarbon fuel conversion to syngas were developed. A compact on-board syngas generator mounted under the motor hood and a generator control system adapted to the engine control system were designed. It was shown experimentally that the suggested solution allows a reduction of 13– 40% in the fuel rate depending on the operating mode under the urban cycle conditions and considerably decreases the release of CO, CO2, and NOx. Prospects for the applications of this technology for creating ecologically clean engines were assessed.

CATALYSTS FOR THE CONVERSION OF HYDROCARBON AND SYNTHETIC FUELS FOR ONBOARD SYNGAS GENERATORS

V.A. Kirillov, N.A. Kuzin, Yu.I. Amosov, V.V. Kireenkov, V.A. Sobyanin

Catal. Ind., 3(2) (2011) pp. 176-182.

The use of syngas derived on board a vehicle as a supplement to the main fuel fed to engines ensures engine operation using dilute fuel mixtures. This leads to a decrease in emission toxicity and an increase in the fuel efficiency of the engine. The preparation of new types of efficient catalysts for the conversion of hydrocarbon and synthetic fuels for onboard syngas generators requires the use of new approaches to the design of catalysts not only as catalytically active material, but also as a structural component of a chemical reactor. The authors prepared and tested a set of catalysts for the conversion of hydrocarbons, i.e., natural gas, diesel and biodiesel fuels, biofuels, and alcohols (ethanol, methanol) to syngas. Primary supports for the catalysts were metals grids and porous tapes; secondary supports were oxides of aluminum and magnesium deposited on or sintered to a primary support. The catalysts exhibited high thermal stability and mechanical strength, and were characterized by the conformity of the coefficients of thermal expansion of the support material and the catalytically active bed. The catalysts can be used as structural components of reactors and as a basis for the preparation of monolithic blocks and planar components of radial and planar reactors. The developed catalysts were subjected to laboratory and bench tests and examined as components of onboard generators of vehicles.

USE OF Pd MEMBRANES IN CATALYTIC REACTORS FOR STEAM METHANE REFORMING FOR PURE HYDROGEN PRODUCTION

A.B. Shigarov, V.D. Meshcheryakov, V.A. Kirillov

Theor. Found. Chem. Eng., 45(5) (2011) pp. 595-609.

This review analyzes publications on experimental studies and mathematical modeling in the field of development of a catalytic reformer (mainly, steam methane conversion) with a fixed catalytic bed. The specific feature of such a reformer is its integration with a Pd membrane for the purpose of producing high-purity hydrogen to power a low-temperature fuel cell battery.

DESIGN, SCALE-OUT, AND OPERATION OF A PREFERENTIAL CO METHANATION REACTOR WITH A NICKEL–CERIA CATALYST

M.M. Zyryanova, P.V. Snytnikov, Yu.I. Amosov, V.A. Kuzmin, V.A. Kirillov, V.A. Sobyanin

Chem. Eng. J., 176-177 (2011) pp. 106-113.

Preferential CO methanation in a reformate gas was investigated over 10 wt% Ni/CeO2 pelleted catalyst in the fixed-bed reactor. It provided the reduction of the CO concentration in the reformate gas to less than 10 ppm over wide temperature interval (250–300°C), while keeping hydrogen consumption relatively low.

The design, scale-out, and operation of a preferential CO methanation reactor with integrated heatexchanger were reported. The nickel–ceria catalyst was deposited onto metal gauzes, assembled into catalytic blocks. Direct contact of the catalyst with metal support provided high heat conductivity of the assembly and feasible temperature control upon variation of operation regimes. Nickel–ceria catalyst showed high activity and selectivity for the reaction of CO methanation in the presence of CO2 excess. The preferential CO methanation reactor allowed the decrease of CO concentration to less than 20 ppm in realistic reformate generated by fuel processor via the reaction of methane steam reforming followed by CO water gas shift reaction.

SORPTION PROPERTIES OF LITHIUM CARBONATE DOPED CaO AND ITS PERFORMANCE IN SORPTION ENHANCED METHANE REFORMING

V.S. Derevshchikov, A.I. Lysikov, A.G. Okunev

Chem. Eng. Sci., 66(13) (2011) pp. 3030-3038.

In-house prepared lithium carbonate doped CaO was tested for its CO2 sorption properties and suitability as a CO2 sorbent for sorption-enhanced reforming of methane. The new material demonstrated CO2 capacity at the temperatures above the equilibrium for CaO recarbonation reaction. However, the capacity was unstable and decreased during carbonation–regeneration cycles. After sufficiently large number of cycles Li dopant escaped from the sorbent and its sorption behavior resembled to that of CaO. The main route of escape is, probably, a

crossover of liquid Li2CO3 onto crucible in TG experiments and onto catalyst in SER tests. Sorption enhanced methane reforming at 2 bar pressure, 750°C and H2O to CH4 ratio of 4 using novel sorbent yielded as high as 99.8 vol% pure hydrogen during the first cycle. In subsequent cycles the hydrogen purity drastically decreased as a result of severe catalyst poisoning by Li.

HIGH TEMPERATURE CaO/Y2O3 CARBON DIOXIDE ABSORBENT WITH ENHANCED STABILITY FOR SORPTION-ENHANCED REFORMING APPLICATIONS

V.S. Derevshchikov, A.I. Lysikov, A.G. Okunev

Ind. Eng. Chem. Res., 50(22) (2011) pp 12741-12749.

To improve the stability of high temperature CO2 absorbent for sorption enhanced reforming applications yttria supported CaO were synthesized using two methods: calcination of mixed salt precursors and wet impregnation of yttria support. According to XRD data, CaO does not interact with the yttria matrix. However, introduction of CaO drastically changes the morphology of primary yttria particles. Increase in CaO concentration results in gradual plugging of the smaller pores and sintering of yttria support. The CO2 absorption uptake in recarbonation-decomposition cycles increases with increase in CaO content and reach 9.6 wt% at CaO content of 19.9 wt%. CaO recarbonation extent varies from 49 to 77%. CaO/Y2O3 absorbents are extremely stable under overheating and maintain their capacity in long series of decomposition-recarbonation cycles even after calcination at 1350°C. The novel material resists moisture and retains its strength during storage in the air. According to tests, CaO/Y2O3 can be considered as a promising CO2 absorbent for fixed bed sorption enhanced hydrocarbons reforming.

EFFECT EXERTED BY TEXTURE OF CALCINED CALCIUM OXIDE ON ITS SORPTION CAPACITY IN THE CO2 SORPTION-REGENERATION CYCLES

A.G. Okunev, A.I. Lysikov

Russ. J. Appl. Chem., 84(2) (2011) pp. 173-178.

The dynamic capacity of a set of sorbents prepared by calcination of different precursors was studied in multiple CO2 sorption-regeneration cycles.

The effect exerted by type of a precursor and calcination temperature on the steady state value of the dynamic capacity attained after several tens of cycles was determined. A model was suggested for estimate of the sorption capacity of CaO sintered above the Tammann temperature from data on the mercury porosimetry.

PROMISING CHEMICAL ADSORPTION CYCLIC PROCESSES FOR СО2 ISOLATION FROM SMOKE FUMES

A.G. Okunev, A.I. Lysikov

Chem. Sustain. Devel., 19(1) (2011) pp. 105-112.

Promising cyclic processes of hydrocarbon combustion distinguished by the type of the chemisorbent used are considered. In the carbonate cycle, solid high-temperature regenerable chemisorbent for СО2 is used to isolate carbon dioxide. In the oxygen cycle, a solid chemisorbent of oxygen is used; it gets recovered when in contact with fuel and gets oxidized when in contact with the air. A common feature of these processes includes solid-phase reactions of binding and release of the products or reagents at different stages of the process. Requirements to chemisorbents for cyclic processes are determined. Various factors affecting the efficiency of their use are considered, literature data on the efficiency of the proposed cycles of СО2 concentrating are reported.

PROTON CONDUCTING HYDROCARBON MEMBRANES: PERFORMANCE EVALUATION FOR ROOM TEMPERATURE DIRECT METHANOL FUEL CELLS

I.M. Krivobokov, E.N. Gribov, A.G. Okunev

Electrochim. Acta, 56(5) (2011) pp. 2420-2427.

The methanol permeability, proton conductivity, water uptake and power densities of direct methanol fuel cells (DMFCs) at room temperature are reported for sulfonated hydrocarbon (sHC) and perfluorinated (PFSA) membranes from Fumatech®, and compared to Nafion® membranes. The sHC membranes exhibit lower proton conductivity (25–40 mS cm-1 vs. ∼95–40 mS cm-1 for Nafion®) as well as lower methanol permeability (1.8–3.9 × 10-7 cm2 s-1 vs. 2.4-3.4 × 10-6 cm2 s-1 for Nafion®). Water uptake was similar for all membranes (18–25 wt%), except for the

PFSA membrane (14 wt%). Methanol uptake varied from 67 wt% for Nafion® to 17 wt% for PFSA. The power density of Nafion® in DMFCs at room temperature decreases with membrane thickness from 26 mW cm-2 for Nafion® 117 to 12.5 mW cm-2 for Nafion® 112. The maximum power density of the Fumatech® membranes ranges from 4 to 13 mW cm-1. Conventional transport parameters such as membrane selectivity fail to predict membrane performance in DMFCs. Reliable and easily interpretable results are obtained when the power density is plotted as a function of the transport factor (TF), which is the product of proton concentration in the swollen membrane and the methanol flux. At low TF values, cell performance is limited by low proton conductivity, whereas at high TF values it decreases due to methanol crossover. The highest maximum power density corresponds to intermediate values of TF.

PYROLYSIS OF LIQUID HEXADECANE WITH SELECTIVE MICROWAVE HEATING OF THE CATALYST

E.I. Udalov, V.A. Bolotov, Yu.Yu. Tanashev, Yu.D. Chernousov*, V.N. Parmon (*Institute of Chemical Kinetics and Combustion, Novosibirsk, Russia)

Theor. Exp. Chem., 46(6) (2011) pp. 384-392.

The pyrolysis of liquid n-hexadecane was studied on various catalysts with selective microwave (MW) heating of a catalyst possessing much greater microwave absorption capacity than the long-chain hydrocarbon studied. This method permits rapid heating of the catalyst to temperatures much higher than 400°C, leading to reflux of the liquid substrate, movement of the catalyst granules within the substrate, and chemical transformations (cracking) of hexadecane. High pyrolysis selectivity relative to α-olefins was found on various catalysts such as magnetic microspheres (coal combustion ash), Al2O3/Al, and Pd/KTP (glass fiber). This behavior may be attributed to tempering of the primary products in the bulk of the liquid reagent. Furthermore, MW pyrolysis on magnetic microspheres was found to be accompanied by formation of rather thick carbon microfibers with diameter 300-500 nm.

ANALYSIS OF THE DEACTIVATION OF CLAUS ALUMINA CATALYST DURING ITS INDUSTRIAL EXPLOITATION

P.N. Kalinkin, O.N. Kovalenko, O.I. Platonov* (*Gipronickel Institute, LTD, St. Petersburg, Russia)

Catal. Ind., 3(2) (2011) pp. 183-188.

Change in the activity of AO-NKZ-2 (AO-MK-2) alumina catalyst in the Claus reaction and transformations of carbonyl sulfide during operation over four years in the Claus reactor at the Magnitogorsk Metallurgical Combine’s coke-oven gas purification shop were studied at an average temperature of 245–260°C and a volume velocity of ~2000 h–1. The rate constants of the Claus reactions and COS transformation were determined, and the changes in the active surface area of the catalyst were investigated. Fundamental discrepancies in the rate and deactivation mechanism of the Claus catalysts were revealed with respect to the reactions of the conversion of hydrogen sulfide and carbonyl sulfide.

SELECTION OF MODIFYING ADDITIVES FOR IMPROVING THE STEAM TOLERANCE OF METHANE AFTERBURNING PALLADIUM CATALYSTS

M.A. Mashkovtsev*, A.K. Khudorozhkov, I.E. Beck, A.V. Porsin, I.P. Prosvirin, V.N. Rychkov*, V.I. Bukhtiyarov (*Ural Federal University, Yekaterinburg, Russia).

Catal. Ind., 3(4) (2011) pp. 350-357.

In this work, the authors discuss the problem of the afterburning of methane from the exhaust gases of automobile engines fueled by natural gas. In exhaust neutralizers, the PdO/Al2O3 catalyst, the main drawback of which is the reduction of its activity under the action of steam that always present in exhaust gases, is commonly used. To improve the tolerance to steam, a series of PdO-MexOy /Al2O3 binary catalysts (Me is Co, Cu, Fe, Ni, Mn, or Sn) was prepared and studied. Comparative tests under conditions modeling the methane afterburning process in automobile neutralizers show that Pd catalysts promoted with nickel, cobalt, and tin oxides are more resistant to the inhibiting action of steam. The high crystallinity of supported PdO and its uniform distribution over the surface of modified Al2O3 are indicated as criteria for the stability of catalysts in the presence of steam. Optimization of the concentration of promotors and the preparation method used for their introduction allows the deactivation of Pd catalysts under the action of steam to be almost completely eliminated.

CATALYTIC TECHNOLOGIES BASED ON APPLICATION OF GLASS-FIBER CATALYSTS

A.N. Zagoruiko, B.S. Bal’zhinimaev

Chem. Ind. Today, 2 (2011) pp. 2-11.

Engineering questions of catalytic technologies based on application of new generation of catalysts on glass-fiber carriers are discussed.

MICROCHANNEL CATALYTIC SYSTEMS FOR THE INTENSIFICATION OF HYDROGEN PRODUCTION FROM CARBON-CONTAINING FEEDSTOCKS

L.L. Makarshin, V.N. Parmon

Catal. Ind., 4(1) (2012) pp. 27-38.

In the early 1990’s, the progress in modern microelectronic technologies gave an impetus to studies of specific behavior of microchannel systems in various physicochemical processes. The microchannel systems were shown, with heat exchangers, mixers and microchannel reactors (microreactors) as examples, to intensify all the processes in the microchannels. In the present review paper, principal criteria, that make possible to classify a flow system as the microchannel one, are discussed. Three main catalytic processes – steam conversion, partial oxidation and autothermal conversion of light hydrocarbons and alcohols into hydrogen-containing gas – are considered and analyzed. It is shown with methane and methanol as examples that the process of hydrogen generation is enhanced indeed in the microreactor. In steam conversion of methanol catalyzed by Zn/TiO2 at 450°C, the specific hydrogen productivity per catalyst weight was as high as 78,6 L/(h·gcat), the outlet quantity of carbon monoxide being no more than 1 mol.%. In partial oxidation of methane over catalyst La0,2Zr0,4Ce0,4/LaNiPt (0,48 g) in a microreactor at 700°C, the specific hydrogen productivity was 521 L/(h·gcat) per catalyst weight and 42 L/(h·cm3) per reaction zone volume. When so, the thermal capacity (heat generated at hydrogen combustion) is 117 kW for the microreactor with 1,0 dm3 reaction volume that is comparable to the power of the gasoline engine of a modern vehicle. Hydrogen production from bioethanol, gasoline and diesel fuel also seems promising. Inspection of relevant literature in the field demonstrated that these fuels can compete successfully with methanol and methane, even though the catalytic conversion proceeds at temperatures 650°C or higher. Results obtained in developing fuel cell – catalytic generators of hydrogen-containing gas with a low content of carbon monoxide (less than 20 ppm) – are reported in the last Section. Integrated microchannel systems are shown to be the most promising fuel cells.

CATALYTIC PARTIAL OXIDATION OF METHANE IN MICROCHANNEL REACTORS WITH CO-CURRENT AND COUNTERCURRENT REAGENT FLOWS: AN EXPERIMENTAL COMPARISON

L.L. Makarshin, D.V. Andreev, A.G. Gribovskii, V.N. Parmon

Chem. Eng. J., 178(15) (2011) pp. 276-281.

Microchannel catalytic reactors have repeatedly proved their high efficiency in the process of partial oxidation of methane (POM) as compared to traditional fixed-bed catalytic reactors. However, a serious problem of the microchannel reactor operation at this process appears to be high thermal power evolved on the narrow front edge of the microchannel (MC) plates. As a result, the front edge of the plates may undergo thermal corrosion and destruction during the POM process. The way out is to develop microchannel plates, which design would provide a countercurrent reagents flow inside the reactors. A comparison of the operation of microchannel reactors using co-current and countercurrent reagent flows shows substantial advantages of the latter. At high and prolong heating load, a microchannel reactor with the countercurrent reagent flow (MCR-Z) outperforms a reactor with the co-current reagent flow (MCR-P) both in the methane conversion and carbon monoxide selectivity. This is associated with the lower temperature of the front edge of the microchannel plate as well as the lower inner temperature gradient in the MCR-Z in comparison to the MCR-P. Thus, the countercurrent flow scheme allows solving some serious problems of corrosion and destruction of the microchannel plate front edge at high heat loads during the POM process.

USING CATALYSTS BASED ON MOLYBDENUM AND TUNGSTEN CARBIDES IN THE WATER-GAS SHIFT REACTION

G.L. Semin, A.R. Dubrovsky*, P.V. Snytnikov, S.A. Kuznetsov*, V.A. Sobyanin (*Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials, Murmansk Region, Apatity, Russia)

Catal. Ind., 4(1) (2012) pp. 59-66.

The review presents data on the main areas of application of molybdenum and tungsten carbides as catalysts for several industrially important reactions and the basic solutions for the synthesis of catalysts. Some of these methods can be considered as the initial phase of technology development of industrial catalysts based on molybdenum and tungsten carbides. The greatest prospect as a catalyst in the CO conversion by water vapor have a composition based on Mo2C.

ECOLOGICAL AND ENERGY ASPECTS OF THE PROPANE DEHYDROGENATION PROCESS REALIZED IN THE MEMBRANE REACTOR

E.V. Shelepova, A.A. Vedyagin

Alternative Energy Ecol., 2 (2011) pp. 98-101.

The both energy and ecological aspects of propylene production in the membrane reactor were analyzed. An approach considering the simultaneous occurrence of the thermodynamically conjugated reactions in the membrane reactor has been suggested and theoretically realized. Such method allows one to reduce the contribution of side reactions due to shifting the equilibrium of the propane dehydrogenation reaction towards formation of propylene. The effect of hydrogen oxidation in the membrane reactor upon the propane conversion has been studied. It was shown that the heat of hydrogen oxidation reaction allows one to minimize energy operating costs for the process of propane dehydrogenation.

KINETICS OF PHENOL HYDROGENATION OVER Pd-CONTAINING HYPERCROSSLINKED POLYSTYRENE

E.M. Sulman*, A.A. Ivanov, V.S. Chernyavskii, M.G. Sulman*, A.I. Bykov*, A.I. Sidorov*, V.Yu. Doluda*, V.G. Matveeva*, L.M. Bronstein**, B.D. Stein**, A.S. Kharitonov

(*Tver Technical University, Tver, Russia; **Indiana University, Bloomington, IN, USA)

Chem. Eng. J., 176-177 (2011) pp. 33-41.

Hypercrosslinked polystyrene (HPS) has been used as a support for preparation of the palladium-based catalyst, Pd/HPS, for gas phase hydrogenation of phenol to cyclohexanone. At the phenol conversion 99%, the catalyst provides selectivity for ketone not lower than 95 mol%. The Pd/HPS catalyst showed high stability, retaining its catalytic performance at least for 20 days. Kinetics was used to compare Pd/HPS with the commercial Pd/Al2O3 catalyst. The catalytic efficiency was assessed using the derived dimensionless kinetic equation without a ‘time’ parameter. Three major reaction routes with their rate parameters and activation energies were revealed. From kinetic parameters, the maximum possible yield of cyclohexanone in the temperature range of 120– 180°C was determined. The important feature of the Pd/HPS catalyst is that selectivity is independent of the temperature at a certain phenol conversion. At elevated temperatures (160–180°C), the selectivity is at least 2–3% higher as compared to the commercial catalyst Pd/Al2O3, which makes Pd/HPS largely promising for industrial applications.

DEHYDROGENATION OF PROPANE–ISOBUTANE MIXTURE IN A FLUIDIZED BED REACTOR OVER Cr2O3/Al2O3 CATALYST: EXPERIMENTAL STUDIES AND MATHEMATICAL MODELLING

N.V. Vernikovskaya, I.G. Savin*, V.N. Kashkin, N.A. Pakhomov, An. Yermakova,

V.V. Molchanov, E.I. Nemykina, O.A. Parahin** (*JSC “Tobolsk-Neftehim”, Tobolsk, Russia; **JSC “NPK Sintez”, Barnaul, Russia)

Chem. Eng. J., 176-177 (2011) pp. 158-164.

An influence of propane addition to the inlet feed on the performance of industrial fluid bed reactor for isobutane dehydrogenation was experimentally and numerically studied. Experiments on dehydrogenation of propane–isobutane mixture in a pilot fluidized and

in a lab fixed bed reactors were performed over Cr2O3/Al2O3 industrial catalyst. Adding C3H8 to the reactor inlet was found to increase experimental conversion of C3–C4 mixture and the total process selectivity to olefins. Results of the mathematical modelling of the industrial-scale fluidized bed reactor show some benefits of C3H8 addition. Selectivity to i-C4H8 was found to be high enough and grows slightly from 86 to 89% on increasing inlet C3H8 fraction from 0 to 60 wt%. Inlet concentrations of C3H8 up to 20 wt% lead to the apparent selectivity to C3H6 exceeding 100%. Coke yield rises slowly allowing safe industrial fluid bed reactor operation.

CATALYTIC DEHYDRATION OF BIOETHANOL TO ETHYLENE: PILOT-SCALE STUDIES AND PROCESS SIMULATION

A.P. Kagyrmanova, V.A. Chumachenko, V.N. Korotkikh, V.N. Kashkin, A.S. Noskov

Chem. Eng. J., 176-177 (2011) pp. 188-194.

Process of bioethanol dehydration to ethylene over alumina-based catalyst in tubular fixed bed reactor was studied both experimentally and numerically. Kinetic studies were carried out to determine the reaction network, to estimate the parameters of the kinetic model and to find the optimal conditions that provide the maximal ethylene yield in the reaction of bioethanol dehydration. Pilot scale studies and process simulation were carried out to determine the optimal technological regimes in a single catalyst tube as an element of a multi-tubular reactor. The optimal characteristics and process parameters of industrial tubular fixed bed reactor for ethylene production from bioethanol at capacity of 60,000 TPA have been determined.

INFLUENCE OF ADDITIVES IN THE BATCH ON BENZOPYRENE EMISSION DURING THE PRODUCTION OF ANODIC CARBON AND GRAPHITE

Ch.N. Barnakov*, A.P. Kozlov*, V.I. Malysheva*, Z.R. Ismagilov, V.F. Anufrienko, V.N. Parmon

(*Institute of Coal-Chemistry and Material Science, Kemerovo, Russia)

Coke Chem., 54(7) (2011) pp. 241-243.

The influence of various additives to the initial batch on benzopyrene emissions is investigated, both in the production of self-sintering anodes and in the

formation of green anodes for graphite production. Benzopyrene is bound in the presence of transition-metal compounds at 600–1000°C.

A CAPILLARY GAS CHROMATOGRAPHIC COLUMN WITH A POROUS LAYER BASED ON THE DIVINYLBENZENE-VINYLIMIDAZOLE COPOLYMER

O.A. Nikolaeva, Yu.V. Patrushev, V.N. Sidelnikov

Russ. J. Phys. Chem. A, 85(9) (2011) pp. 1647-1651.

Capillary columns with a new sorbent based on the divinylbenzene-vinylimidazole organic copolymer are proposed. The properties of the prepared columns are discussed. It is demonstrated that columns based on the divinylbenzene-vinylimidazole polymer with different selectivities can be prepared by varying the relative amount of vinylimidazole in the initial polymerization mixture. The examples of separation of light hydrocarbons, permanent gases, and oxygen-containing compounds are given.

LIQUID-PHASE DECHLORINATION OF TOXIC TECHNOGENIC PRODUCTS USING NANO-DISPERSED PALLADIUM CATALYSTS BASED ON SIBUNIT

A.V. Mekhaev*, M.G. Pervova*, O.P. Taran, I.L. Simakova, V.N. Parmon, M.A. Samorukova*, V.P. Boyarskii**, T.E. Zhesko**, V.I. Saloutin*, Yu.G. Yaltuk* (*Postovsky Institute of Organic Synthesis Yekaterinburg, Russia; **St.-Petersburg State University, St. Petersburg, Russia)

Chem. Sustain. Devel., 19(2) (2011) pp. 179-186.

Liquid-phase catalytic reductive dechlorination of toxic technogenic products using catalysts M/Sibunit (M = Ni, Pt, Pd) was investigated. It was shown that the highest activity is exhibited by catalysts based on palladium.

ADSORPTION-CATALYTIC NEUTRALIZATION OF EXHAUST GASES OF DIESEL ENGINES

I.V. Mishakov, A.A. Vedyagin, A.M. Volodin, M.S. Myakisheva

Chem. Sustain. Devel., 19(1) (2011) pp. 97-104.

The basic aspects of environmental protection from hazardous gaseous impurities present in the exhaust gases of diesel engines are considered. Approaches used for the development of fundamental investigation of adsorbents and catalysts for afterburning СО and hydrocarbons are outlined. Results of the investigation of adsorption capacity of zeolites BEA- and Y-types with respect to heavy hydrocarbons (decane and toluene) obtained with the help of the gravimetric microanalyzer TEOM are presented. It is shown that both zeolites possess comparable capacities with respect to toluene, while the presence of mesopores in BEA-zeolite determines its substantially larger adsorption capcsity with respect to decane. For Pd/Al2O3 catalysts as example, the effect of the nature of precursor of active component and treatment conditions on the activity of the catalysts in the oxidation of CO is considered. It is demonstrated that in the case of the mass fraction of deposited chloride components up to 0.25-0.5 % atomically dispersed forms of palladium are formed; they are responsible for the high activity of palladium catalysts

Страницы 1 - 3 из 3
Начало | Пред. | 1 | След. | Конец | По стр. 



Copyright © catalysis.ru 2005-2023
Политика конфиденциальности в отношении обработки персональных данных