Influence of the metal oxide support on the surface and catalytic properties of sulfated vanadia catalysts for selective oxidation of methanol

The selective oxidation of methanol to dimethoxymethane (DMM) was performed over a series of binary vanadia-based oxides (V2O5single bondTiO2, V2O5single bondZrO2, V2O5single bondAl2O3 and V2O5single bondCeO2) and the corresponding sulfated catalysts. The physicochemical properties of catalysts were characterized by BET, Raman, XPS, TPR–MS, ammonia adsorption calorimetry and sulfate TPD–MS techniques. The strength of the sulfate-support interaction depends on the nature of the oxide support and increases in the following order CeO2 > Al2O3 > ZrO2 > TiO2. The catalytic reactivity was correlated with the nature of Vsingle bondO-support bonds. Sample V2O5single bondTiO2 exhibits the highest intrinsic activity of methanol oxidation. With the addition of sulfate, the selectivity to DMM was enhanced whereas the turnover frequency (TOF) value of vanadium sites decreased, with a rate depending on the strength of sulfate-support bonds. The best catalyst image with higher DMM yield presented higher reducibility, proper acidity and moderate strength of sulfate species.