G. N. Pirogova

Catalytic properties of chromites with a spinel structure in the oxidation of CO and hydrocarbons and reduction of nitrogen oxides

The catalytic activity of supported chromites MCr2O4/γ-Al2O3 (M = Cu, Co, Mn, Zn, Mg) in the oxidation of CO, C3H6, and o-xylene and NOx reduction was studied. The catalytic activity depends on the calcination temperature and cation nature. The features of the formation of the catalysts were studied by the UV-Vis diffuse reflectance and IR spectroscopies.

Oxidation of CO and hydrocarbons over perovskite-type complex oxides

The catalytic activity of perovskites MIMIIO3 (MI=La; MII=Co, Mn, Cr, Al, Ni, and V) and MICoO3 (M=Y, Nd, Sm, and Er) in the oxidation of CO, propylene, and ethylbenzene was investigated. The highest activity was observed for the MICoO3 catalysts with perfect perovskite structure. The nature of the rare-earth element has no influence on the catalytic activity. Deformation of the octahedral coordination of the metal was found for the less active catalysts. The interaction of gases (CO, CO+air) with the catalyst surface was investigated. The more active catalysts adsorb a greater amount of O2, and the adsorption occurs in the temperature region of the oxidation reaction. The activities of the perovskite- and spinel-type catalysts were compared under similar conditions.

Catalytic oxidation of CO and hydrocarbons on SHS-prepared complex metal oxide catalysts

Abstract Complex metal oxides with the structure of spinel type (MeAII)(MeBIII)2O4 based on Co, Ni, Cu, Mn, Cr, Al are synthesized by a self-propagating high-temperature synthesis method (SHS). IR spectroscopy and X-ray analysis are used for studying the structure of the oxides. The tests of the catalytic activity of the complex oxides in CO and hydrocarbons oxidation reactions have shown that the Co-Cr-Al complex oxides possess the most activity. Their activity depends on the ratio of Cr and Al in the spinels and increases with the increase of the chromium content. The samples synthesized in the SHS regime are more defective and, as consequence, more active than the samples produced by reaction sintering. The SHS-catalysts have been manufactured as monolith cellular blocks and have been proven in an industrial application. Results of tests of these catalysts for purification of a waste gases are included.

CATALYTIC OXIDATION OF CO, HYDROCARBONS, AND ETHYL ACETATE OVER PEROVSKITE-TYPE COMPLEX OXIDES

The catalytic activity of MIMIIO3] perovskite-type complex oxides (MI = La, Y, Nd, Yb; MII = Co, Mn, Ni) in the oxidation of CO, propylene, benzene, ethylbenzene,o-xylene, and ethyl acetate was investigated. The Co-containing catalysts were shown to be more active in the oxidation than the Mn-containing catalysts. A relationship between the catalytic and adsorption properties was established.

Catalytic properties of spinel-type complex oxides in oxidation reactions

The catalytic activity of MIMII2O3 spinel-type complex oxides (MI = Cu, Ni, Mn, Zn, Mg, Co, MII = Co, Cr, Al) in the oxidation of CO and ethylbenzene has been investigated. The Co-containing catalysts were more active than the Cr- and Al-containing catalysts. The nature of the cation influenced the catalytic activity. Higher activities were observed for the catalysts containing two transition elements. A correlation between the catalytic and adsorption properties was established.

Catalytic properties of ferrites in oxidation reactions

Catalytic activities of ferrites MFe2O4 (M = Cu, Co, Ni, Mg, and Zn) and M10.5M20 .5Fe2O4 (M1 = CU; M2 = Co, Zn, and Mg) in oxidation of CO and ethylbenzene were investigated, and their dependences on the cation nature were established. Higher activities were observed for catalysts containing ions with variable valence (Cu, Co, and Ni). A correlation between catalytic and adsorption properties of ferrites was found.

Regularities of formation and catalytic properties of supported cobaltites in the oxidation of CO and hydrocarbons and in the reduction of nitrogen oxides

The catalytic properties of supported cobaltites MCo2O4 (M=Cu, Mn, Zn, Mg) in the oxidation of CO, C3H6, and ethylbenzene and reduction of nitrogen oxides were investigated. The catalytic activity depends on the calcination temperature and the nature of the cation. The regularities of formation and the state of the surface of the catalysts were studied by IR spectra and diffuse reflectance spectra in the UV and visible regions.

Hydrogenation of acetone on technetium catalysts

The catalytic properties of supported mono- and bimetallic catalysts of the Tc/support, M/support, and M-Tc/support types (M=Pt, Pd, Rh, Ru, Ni, Re, Co; supports are γ-Al2O3, MgO, SiO2) were investigated in the acetone hydrogenation. The main products of this reaction are isopropyl alcohol and propane. The catalytic activity in the acetone hydrogenation of the metals studied decreases in the consequence Pt>Tc≈Rh>Pd>Ru >Ni≈Re>Co (with γ-Al2O3 as the support). The influence of support nature on the catalytic activity was investigated for the Rh−Tc system as an example. A nonadditive increase in the catalytic activity of Rh−Tc/γ-Al2O3 in comparison with monometallic catalysts was found. The state of the surface of the catalysts was characterized by the UV-VIS diffuse reflectance spectra.

Weakly bound oxygen in the catalytic CO oxidation and exoemission from complex oxides having a spinel structure

The catalytic activity of complex oxides MIMII2O4 (MI=Cu, Ni, Co, Zn, or Mg; MII=Mn or Cr) with a spinel structure in the oxidation of CO and the low-temperature (20–400°C) exoemission of negative charges from their surface were investigated. A relationship between the catalytic activity and the emissivity of the systems under study was found. The role of the charged species of weakly bound oxygen in exoemission and oxidative catalysis by the complex oxides is discussed.

Rhodium-technetium catalysts in the dehydrogenation of cyclohexane

The catalytic properties of a Rh-Tc/support (γ-Al2O3, SiO2, or MgO) system in the dehydrogenation of cyclohexane have been investigated. A nonadditive increase in the catalytic activity of bimetallic catalysts in comparison with monometallic systems has been established. This effect depends on the ratio of the amounts of the supported metals and on the nature of the support. Diffuse reflectance spectra showed the presence of ionic forms of the metals in the bimetallic catalysts. Analysis of the catalytic and optical properties allowed one to draw the conclusion that the synergistic effect is explained by the formation of RhxTcy clusters.