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61.
When characterizing the phase composition and structure of catalysts, researchers are faced with the problem of reversible effects of temperature and gas medium during their preparation, activation, or operation. Therefore, particular attention is paid to the methods of their research in appropriate conditions, i.e., in situ high-temperature X-ray diffraction. The theoretical framework and experimental features of high-temperature X-ray diffraction techniques are examined. Examples are given of their effective application to the study of the structural features of oxide catalysts under close-to-real conditions. 相似文献
62.
Simentsova I. I. Minyukova T. P. Khassin A. A. Dokuchits E. V. Plyasova L. M. Tselyutina M. I. Yurieva T. M. 《Kinetics and Catalysis》2010,51(1):135-138
The dissolution of nickel metal in nitric acid in the presence of the dichromate anion as the oxidizer is reported. The formation
of Ni(II) and Cr(III) nitrates takes place in two steps with the intermediate formation of nitrous acid. A new method to synthesize
the nickel-chromium oxide catalyst from nickel and chromium nitrate solutions is suggested, in which the solutions are obtained
by an environmentally friendly technology from nickel metal, chromium(VI) oxide, and nitric acid. The catalyst is highly active
and selective in benzene hydrogenation and in CO preferential hydrogenation in the presence of CO2. 相似文献
63.
L. M. Plyasova I. Yu. Molina G. N. Kustova G. S. Litvak A. I. Nizovskii A. N. Gavrilov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(6):869-875
A comparative study of tungsten oxide formation from various precursors has been carried out using a complex of physicochemical
methods. Crystallization of WO3 has been shown to pass through metastable states in all cases. For electrodeposited oxotungstate films, the structure of
tungsten oxides depends on electrodeposition conditions and adsorption properties of substrate metal with respect to hydrogen;
at temperatures below 600 °C the stoichiometric composition of WO3 is not attained. 相似文献
64.
Valentina M. Bondareva Tamara V. Andrushkevich Galina I. Aleshina Raisa I. Maksimovskaya Lyudmila M. Plyasova Larisa S. Dovlitova Elena B. Burgina 《Reaction Kinetics and Catalysis Letters》2006,88(1):183-191
Summary Genesis of an active component in V-Mo-Nb-O catalysts for the oxidation and ammoxidation of ethane was studied. It was shown
that the mixing of aqueous solutions of initial reactants leads to the formation of MoV complexes in the solution and to sedimentation
of a binary Nb-Mo compound. The latter serves as the basis for the formation of the catalyst active component phase (a triple
V-Mo-Nb compound with a variable composition of Mo5O14-like structure) during the subsequent treatment in air at 400°C. 相似文献
65.
T. Yu. Kardash L. M. Plyasova V. M. Bondareva T. V. Andrushkevich A. V. Ishchenko Yu. A. Chesalov L. S. Dovlitova 《Kinetics and Catalysis》2009,50(1):48-56
The formation of an active phase in V-Mo-Nb oxide catalysts for the selective oxidation and ammoxidation of ethane during thermal treatment in air and in helium was studied using high-temperature in situ and ex situ X-ray diffraction analysis, transmission electron microscopy, IR spectroscopy, and the differential dissolution method. It was found that, in thermal treatment below 500°C, the formation occurred through the same irreversible steps with the formation of a unidimensionally ordered layered compound with structure elements like Mo5O14 regardless of the calcination atmosphere. Above 500°C, the formation of crystalline phases took place; the composition and structure of these phases depended on the atmosphere of thermal treatment. The unidimensionally ordered V-Nb-Mo oxide with structure elements like Mo5O14 exhibited the best catalytic properties. 相似文献
66.
Aleksandra S. Ivanova Galina S. Litvak Vladimir V. Mokrinskii Lyudmila M. Plyasova Vladimir I. Zaikovskii Vasilii V. Kaichev Aleksandr S. Noskov 《Journal of molecular catalysis. A, Chemical》2009,310(1-2):101-112
Physicochemical and catalytic properties of compositions Fe(Ce)–Mn–O/support (gamma-, theta-, alpha-Al2O3, SiO2 as the support) and Pt/CeO2/theta-Al2O3 for oxidation of soot were characterized. It was established that the phase composition of the initial catalysts depended mainly on the nature of the active component and preparation conditions. Non-isothermal treatment of the soot–catalyst compositions at the temperature up to 1000 °C resulted in a change in the phase composition depending mainly on the final treatment temperature. The catalyst surface area was determined by the support nature. It was established that catalyst activities for oxidation of soot are determined by both catalyst nature and composition of gas mixture. The process of the soot oxidation is thought to involve oxygen from the catalyst surface. The higher proportion of weakly bound surface oxygen, the higher was the catalyst activity. An increase in the oxygen concentration from 5% O2/N2 to 15% O2/N2 is shown to lead to a decrease of the temperature of the soot oxidation. The influence of the oxygen concentration on the process of soot oxidation becomes weaker in the presence of water vapor. Results showed that the presence of NO in the gas mixture favors a decrease in the oxidation temperature of the soot, the higher being the nitrogen oxide concentration, the more pronounced effect. Introduction of SO2 in amount of 50 ppm in the gas mixture has no noticeable effect on the process of the soot oxidation. Among the catalysts under study, Fe–Mn–K–O/gamma-Al2O3 is most effective to oxidation of the soot at otherwise identical conditions. 相似文献
67.
A. N. Gavrilov L. M. Plyasova N. A. Rudina I. Yu. Molina G. A. Tsirlina T. Ya. Safonova 《Russian Journal of Electrochemistry》2004,40(9):981-986
Platinum deposits of submicron thicknesses on polycrystalline gold substrates subjected to different thermal treatments and characterized by texture 200, 311, and 220 are characterized by methods of x-ray diffractometry and scanning electron microscopy. No deposits prepared in a potentiostatic mode exhibit a pronounced texture or a reliable correlation between a weak texture of a deposit and the substrate texture. Established is the difference of predominant directions of secondary nucleation–growth of deposit on neighboring grains of the substrate. The assumption that the deposit includes fragments the size of a few tens of micrometers with pronounced texture of different directions is substantiated. 相似文献
68.
69.
70.
V. I. Lebedeva V. M. Gryaznov I. V. Petrova V. V. Volkov G. F. Tereshchenko E. I. Shkol’nikov L. M. Plyasova D. I. Kochubey R. van der Vaart E. L. J. van Soest-Verecammen 《Kinetics and Catalysis》2006,47(6):867-872
Water deoxygenation has been studied in a catalytic membrane reactor in which oxygen is reduced with hydrogen fed into the hollow fiber of a porous polypropylene membrane containing palladium metal on its outer surface. Palladized fibers obtained by different methods and the initial fibers have been characterized by dynamic desorption porosimetry, gas permeability measurements, X-ray structure determination, and light microscopy. The possibility of efficient water deoxygenation at room temperature is demonstrated. 相似文献