Promotional effects of Sm2O3 on Mn-H4SiW12O40/SiO2 catalyst for dimethyl ether direct-oxidation to dimethoxymethane

The promotional effects of Sm2O3 on Mn-H4SiW12O40/SiO2 for dimethyl ether (DME) direct-oxidation to dimethoxymethane (DMM) were investigated. The results showed that Sm2O3 introduction could significantly improve the activity of Mn-H4SiW12O40/SiO2 for DMM formation, and DMM selectivity was remarkably increased from 36.3% to 60.3% when the Sm2O3 content was 1%. The catalysts were characterized by ICP-AES, XRD, NH3-TPD, Pyridine-IR and XPS. The Sm2O3 introduction enhanced the number of Lewis acid sites and weak acid sites and also increased the amount of Mn4+ species of Mn-H4SiW12O40/SiO2, which is favorable for the formation of DMM.