Aa. Elguezabal et Vc. Corberan, SELECTIVE OXIDATION OF TOLUENE ON V2O5 TIO2/SIO2 CATALYSTS MODIFIED WITH TE, AL, MG, AND K2SO4/, Catalysis today, 32(1-4), 1996, pp. 265-272
The effect of the modification of vanadia catalysts supported on TiO2/
SiO2 by the oxides of Al, Mg and Te, and K2SO4 on the selective oxidat
ion of toluene in the vapor phase has been studied. The catalysts were
prepared by successive impregnation and characterized by BET surface
measurements, XRD, XPS, and TPR. Addition of the second component decr
eased specific activity in all cases, except Al, mainly due to the dec
rease of surface area. Intrinsic activity was increased with addition
of Te and Al, and decreased by that of Mg, while K2SO4, had little eff
ect. These differences could be explained by the observed changes in e
ither vanadium surface dispersion or reducibility. Selectivity to benz
aldehyde increased markedly with addition of Te or K2SO4, that caused
the formation of new oxide phases, V3Ti6O17 and TiV2O6, in which vanad
ium is in a partially reduced state.