Direct synthesis of dimethyl carbonate from CO2 and methanol over a novel CeO2-zeolite Beta composite catalyst

The direct formation of dimethyl carbonate (DMC) from methanol and CO2 becomes a promising method, which can effectively utilize carbon resources and reduce greenhouse gas emissions. In this paper, we first developed a novel oxide-zeolite composite catalyst based on the incorporation of ceria and zeolite Beta (CB), which could significantly modify the suitable concentration of surface acid-base sites and hoisting the number of surface oxygen vacancies or defects, which further improved DMC yield in the direct synthesis of DMC from carbon dioxide and methanol. In particular, the CB-5 composite catalysts hydrothermally prepared by grafting the Ce onto alkali-treated zeolite Beta exhibited the best activity for the direct synthesis of DMC from CO2 and CH3OH than both single component CeO2 and zeolite Beta catalysts, which reached a DMC yield of 1.5 mmol(DMC)/g(Cat). With N-2 sorption, XPS, CO2-TPD, NH3-TPD and other characterization methods, the excellent activity of CB composite catalysts benefited from the synergistic effect of the suitable concentration of surface acid-base sites and increased surface oxygen vacancies. These findings highlighted a feasible approach for the design of high-efficient composite catalysts.