Efficient ceria-manganese oxide for the direct conversion of CO2 and methanol to dimethyl carbonate

A number of Ce1-xMnx catalysts with different Mn contents were prepared by resol-assisted cationic coordinative co-assembly approach and used for the synthesis of dimethyl carbonate (DMC) from CO2 and methanol. Multiple characterizations of XRD, FT-IR, TEM, BET, CO2-TPD, NH3-TPD, H-2-TPR, XPS analyses were applied to investigate the surface properties of the Ce1-xMnx catalysts. It turned out that adjusting the proper concentration of Mn ions not only increased the pore volumes, but also improved the content of medium acidic and medium basic sites. When a small amount of Mn was added, the presence of Mn2+ on the catalyst surface enhanced, facilitating the conversion of Ce4+ to Ce3+, and leading to higher oxygen vacancy concentration. Consequently, the adsorption and activation of CO2 and methanol were promoted, and the catalytic efficiency of the reaction was improved. It was found that Ce0.95Mn0.05 catalyst exhibited the best catalytic activity, achieving a high DMC yield of 6.44 mmol/g (120 degrees C, 6.5 MPa, 4 h).