Effect of silica on the selective oxidation of methanol to dimethoxymethane over vanadia–titania catalysts

V–Ti–O oxides with about 4% sulfate were prepared by a co-precipitation method, which showed strong surface acidic and redox properties, and therefore exhibited good performance for the selective oxidation of methanol to dimethoxymethane (DMM) at relatively low reaction temperatures (e.g., 443 K). However, the selectivity to DMM substantially decreased when reaction temperature increased to higher than 453 K. Addition of SiO2 significantly weakened the surface acidity and redox ability of V–Ti–O, and significantly improved the selectivity to DMM above 453 K. Ninety-three percentage selectivity to DMM with 66% conversion of methanol was obtained over a Si–V–Ti–O catalyst at 483 K.