Selective oxidation of o-xylene to phthalic anhydride on V2O5 supported on TiO2-coated SiO2

A ternary V-Ti-Si catalyst was prepared by depositing the vanadium oxide precursor on a SiO2 previously coated by TiO2. The ternary V-Ti-Si catalyst and the corresponding binary V-Ti and V-Si counterparts were tested for the selective oxidation of o-xylene to phthalic anhydride. Silica-supported vanadium oxide shows lowest activity and selectivity, meanwhile selectivity to phthalic anhydride is higher on titania-containing catalysts. The best yield to phthalic anhydride (82.5%) is obtained at 573 K on the ternary V-Ti-Si catalyst which is comparable to that claimed for the best conventional V-Ti catalysts described in literature.