Vapor-phase oxidation of alkylaromatics over V/TiO₂ and VSb/Al₂O₃ catalysts: Effect of alkali metals

Oxidation of alkylaromatics including toluene and p-methoxytoluene has been carried out over alkali metal (AM)-containing catalysts such as AM-V/TiO ₂ and AM-VSb/Al₂O₃ in vapor-phase using oxygen as an oxidant. The selectivity for partial oxidations increases with incorporation of an alkali metal or with increasing the basicity of alkali metals (from Na to Cs), irrespective of the supports or reactants. However, the conversion is nearly constant or slightly decreasing with the addition of alkali metals in the catalyst. The increased selectivity may be related with the decreased acidity even though more detailed work is necessary to understand the effect of alkali metals in the oxidation. The AM-VSb/Al₂O₃ may be suggested as a potential selective catalyst for vapor-phase oxidations.