Effect of the reduction temperature on the formation and activity of bimetallic Ni-Tc catalysts

The effect of the temperature on the formation, surface state, and catalytic activity in the reactions of dehydrogenation of cyclohexane and dehydrocyclization of n-hexane by Ni-Tc/-Al₂O₃ mono- and bimetallic catalysts was investigated. TcO₂, NiCl₂, and metal phases, and at a high temperature (500–700C), NiAl₂O₄ spinel and Ni-Tc clusters, were found on the surface of all of the catalysts. It was shown that the maximum activity is observed in reduction of monometallic catalysts at 500C and bimetallic catalysts at 700–800C. Synergism appeared in the bimetallic catalysts due to the formation of Ni-Tc clusters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2486–2490, November, 1990.     

Optical absorption of polycrystalline films of zinc telluride,cubic modification

Optical absorption data from a study of polycrystalline films of zinc telluride, cubic modification obtained by different techniques of preparation are reported. It is determined that films having a defective cubic lattice do not show a complex absorption structure. Films having a perfect cubic lattice have a complex absorption spectrum in which three maxima may be measured, at liquid nitrogen temperature, at 5240, 3300, and 2850 Å.     

13C NMR Study of the Structure of Vinyl Chloride-1-Vinyl-1,2,4-triazole Copolymer

The structure of the copolymer prepared by radical copolymerization of vinyl chloride with 1-vinyl-1,2,4-triazole was studied by quantitative ¹³C NMR spectroscopy. The structural unit of the copolymer consists of the units of vinyltriazole and quaternized vinyltriazole, vinyl group, and four vinyl chloride units.     

Catalytic properties of ferrites in oxidation reactions

Catalytic activities of ferrites MFe₂O₄ (M = Cu, Co, Ni, Mg, and Zn) and M¹ _0.5M² _{0 .5}Fe₂O₄ (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.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 49–52, January, 1996.     

Synergistic effect for bimetallic Ru-Tc catalysts of cyclohexane dehydrogenation

Catalytic properties of the Ru-Tc/support (-Al₂O₃, Y₂O₃, and SiO₂) systems in the dehydrogenation of cyclohexane have been studied. The catalytic activity of the bimetallic catalysts depends on the nature of the support. A nonadditive increase in the catalytic activity of the bimetallic catalysts in comparison with monometallic samples was established. The value of the synergistic effect depends on the ratio between the amounts of the supported metals and the nature of the support. By using the diffuse reflectance spectra in UV- and visible regions and hydrogen chemisorption techniques, the modifying influence of the ionic metal species on the catalytic properties was shown.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1959–1963, August, 1996.     

Oxidation of CO and hydrocarbons over perovskite-type complex oxides

The catalytic activity of perovskites M^IM^IIO₃ (M^I=La; M^II=Co, Mn, Cr, Al, Ni, and V) and M^ICoO₃ (M=Y, Nd, Sm, and Er) in the oxidation of CO, propylene, and ethylbenzene was investigated. The highest activity was observed for the M^ICoO₃ 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. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 698–701, April, 1999.