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The catalytic activity of perovskites MIMIIO3 (M I = La; M l! = Co, Mn, Cr, A1, Ni, and V) and MICoO 3 (M = Y, Nd, Sm, and Er) in the oxidation of CO, propylene, and ethylben~ene was investigated. The highest activity was observed for the MICoO:3 catalysts with perfect perovskite structure. The nature of the rare-ear;tin 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 adso~ a greater amount of O2, and the adsorpfior~ occurs in the temperature region of the oxidation reaction. The activities of the perovskiteand spinel-type catalysts were compared under similar conditions.

The catalytic properties of supported cobaltites MCo?O+ (M = Cu, Mn, Zn. Mg) in the oxidation of CO+ C3Ht,, and ethylbenzene and reduction of nitrogen oxides were investigated. The catalytic activity depends on the calcination temperature and the nature of the cation. The regularitie~ or" formation and the state of the surface of the catalysts were studied by I R spectra and diffuse ret]ec:ance spectra in the UV and ~,isible regions.Key words: catalytic oxidation, mtrogen oxide reduction, cobattite, carhon monoxide, propytene, ethy!benzene+The problem of removal of pollutants from exhaust gases has shifted emphasis on catalytic research toward the development of bifunctional catalysts active both in CO and hydrocarbon oxidation and, simultaneously, in the reduction of nitrogen oxides. Of materials containing no platinum-group metats, complex oxides with the spinel structure are promising catalysts for the elimination of pollutants from exhaust gases, The activity of spinels in oxidation is due to the presence in their structure of active oxygen and oxygen vacancies, acting as centers of activation of the gas-phase oxygen. I-4 Previously, s it has been shown that spinels of some metals are active in the oxidation of CO and ethylbenzene.The purpose of this work is to study the regularities of the formation of supported cobaltites synthesized at different temperatures and to perform comparative analysis of their catalytic properties in the oxidation of CO, C3H~, and ethylbenzene and in the reduction of nitrogen oxides. The cobattites studied had the composition , |C020417-A120 3 (M = Cu, ,M+,~, Zn. Mn). ExperimentalThe catalysts were prepared by impregnating 7-AI10 3 (IC-02-200) with a solution containing equimolar amounts of Co1'NO3) 2 and the nitrate of the required metal. After d~mg. the mixture was heated to 350, 500. and 700 ~C and kept at each temperature for 6 h.Bulk spinels were prepared by thorough mixing of equimotar amounts of the corresponding nitrates. The mixture was dried t~r I h at 150 r and then heated for 6 h at 5(~'0 ~ According to X-ray diffraction analysis, in addition to spinels, the catalysts contained minor amounts of individual oxides. The presence of spinel structures was confirmed using I R spectra, based on the presence of two characteristic bands in the 40t)--700 cm -I range.Catalytic oxidation or co and C31-1~ was carried out in a flow-type reactor at a t]ow rate ofP00 h -q. The reaction mixture contained 5--6% CO (or C3Ho) and 94--95% air. The reaction products were analyzed by GC (heat conductivity detector, He as the carrier gas, I-m-long column packed with 5A molecular sie~es ((or determination of CO) or with polysorb (for determination of CO2)).Ethylbenzene oxidation was studied in a flow-type reactor using a KI+-I setup (Special Design Office, Institute of Organic Chemistry, Moscow). The concentration of ethylbenzene was I -l0 -'~ tool L -!, the flow rate was 6000 h -I. The concentration or ethylbenzene was determined by chromatography using a procedure reported previously. 5Nitro...

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