Catalytic oxidation of benzene by doped vanadium pentoxide

Abstract

Rate data for the oxidation of benzene over a series of supported V 2O 5 catalysts have been obtained at various temperatures in the range 300–440 †C. Additions of GeO 2 and MoO 3 to V 2O 5 did not affect the ratio of benzoquinone: maleic anhydride: carbon dioxide (from complete oxidation), obtained as reaction products. It is shown that addition of GeO 2 to V 2O 5 increased the apparent activation energy of the catalytic reaction, whereas, addition of MoO 3 had comparatively little effect. X-ray and semiconductivity data of these oxide systems indicate that within the limits used, up to a nominal 16 mole % GeO 2 and MoO 3, the additive was completely miscible with V 2O 5 and resulted in a decrease and an increase, respectively, of the number of quasi-free electrons associated with the host oxide. It is concluded that the slow stage in the catalytic oxidation of benzene, in the temperature range investigated, depends upon the electron concentration and the oxide composition at the catalyst surface.