Valentin F. Tretyakov

Monolith perovskite catalysts of honeycomb structure for fuel combustion

New method of dispersed perovskites synthesis based upon mechanochemical activation of the solid starting compounds is elaborated. The influence of defect structure of these compounds as well as surface segregation on their catalytic properties is discussed. Basic stages of the monolith perovskite catalysts preparation are optimized. The experimental samples of monolith catalysts of various shapes are obtained, possessing high activity, thermal stability and resistance to catalytic poisons.

Monolith perovskite catalysts for environmentally benign fuels combustion and toxic wastes incineration

Abstract Monolith perovskite catalysts for high-temperature applications (fuels combustion, toxic wastes incineration, hydrocarbons reforming, sulfur dioxide reduction, etc.) were elaborated. Basic stages of these catalysts manufacturing (synthesis of perovskites ultradispersed powders via effective wasteless plasmochemical and mechanochemical routes, monoliths shaping by extrusion with subsequent drying and calcination) were developed. Pilot testing in a number of high-temperature catalytic processes demonstrated efficiency, thermal stability and thermal shock resistance of monolithic perovskites.

Cu, Co, Ag-Containing Pillared Clays as Catalysts for the Selective Reduction of NOx by Hydrocarbons in an Excess of Oxygen

Thermally stable Al- and Zr-PILC loaded with copper and cobalt cations and silver nanoparticles were synthesized. The structural and surface features of these nanosystems were studied and compared with those of bulk analogs – partially stabilized ZrO2 loaded with the same active components. Specificity of the catalytic properties of nanocomposites in SCR of NOx by propane, propylene and decane in the excess of oxygen appears to be determined both by distribution of active components on the catalytic surface and degree of their interaction with supports. Formation of ads.-NOx, nitroxyl-hydrocarbon CxHyNO2⋅ and isocyanate NCO intermediates was observed by ESR and IR spectroscopy in situ.

Nanocomposites Based Upon Alumina and Zirconia Pillared Clays Loaded with Transition Metal Cations and Clusters of Precious Metals: Synthesis, Properties and Catalysis of NO x Selective Reduction by Hydrocarbons

Thermally stable alumina and zirconia pillared clays loaded with copper and cobalt cations and silver nanoparticles were synthesized. The structural and surface features of these nanosystems were studied and compared with those of bulk analogs -partially stabilized zirconias and γ-alumina loaded with the same active components. Specificity of the catalytic properties of nanocomposites in the reactions of nitrogen oxides reduction by propane, propylene and decane in the excess of oxygen appears to be determined both by the degree of interaction between pillars and active components and the type of reducing agent.

The mechanism of selective NOx reduction by hydrocarbons in excess oxygen on oxide catalysts: V. Adsorption properties of a commercial Ni-Cr oxide catalyst

According to X-ray diffraction data, the STK catalyst is a mixture of Fe2O3 and Cr2O3. The temperature-programmed reduction spectrum exhibited two reduction peaks: one, with Tmax = 250°C, corresponds to the reduction process Cr2O3 → CrO and the other, with Tmax = 360°C, corresponds to the reduction Fe2O3 → Fe3O4. The results of thermal desorption measurements suggest that the individual adsorption of oxygen on the surface of the STK catalyst is low; in this case (according to IR-spectroscopic data), an atomic form is the main species. Surface nitrite-nitrate complexes are formed upon the adsorption of NO. Nitrite and nitrate complexes desorbed at maximum rates at 105 and 160°C, respectively. Unlike the NTK-10-1 catalyst, the NO species, which desorbed at high temperatures (250–400°C), was absent from the surface of STK. Propane adsorbed at room temperature to form surface compounds containing an acetate group. The interaction of propane with the surface of the STK catalyst at reaction temperatures resulted in strong surface reduction.

Synergistic Effect in Selective Reduction of NO by Alkanes over Mechanically Mixed Oxide Catalysts

The process of selective catalytic reduction of nitrogen oxides by propane in the presence of O2, as well as in the presence or absence of CO, was studied over series of commercial oxide catalysts used in petrochemical processes. For the first time synergistic effect was observed for catalytic systems consisting of mechanical mixtures of Cu–Zn–Ni–Al (catalyst I) + Fe–Cr (catalyst II) and Cu–Zn–Ni–Al (catalyst I) + Ni–Cr (catalyst III). The activity of these mixtures in nitrogen oxides reduction by propane was greater than that of individual components in each case. The worked-out catalytical systems showed high effectivity in the process of simultaneous removal of several toxic components: NOx, CO, hydrocarbons – from model gas mixtures, as well as from real exhausts of automotive transport.

Redox transformations in the surface layer of complex RBa2Cu3Oy oxides (R = Nd, Ho, Y) and their catalytic properties in CO oxidation

Initial stages of redox transformations in the surface layers of complex RBa2Cu3Oy oxides (R = Nd, Ho, Y) in the course of their interaction with CO and O2 are studied under non-steady-state conditions by a pulse microcatalytic method. It is shown that the interaction of RBa2Cu3Oy phases (R = Y, Ho, Nd) with CO results in the removal of a weakly bound oxygen and in the formation of a surface layer of RBa2Cu3Oy reduction products. It is found that RBa2Cu3Oy oxides retain their ability to be oxidized after reductive treatment. Oxygen from the bulk phases of multicomponent RBa2Cu3Oy oxides can take part in the catalytic oxidation of CO.