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

A number of Ce_1-xMn_x 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, H₂-TPR, XPS analyses were applied to investigate the surface properties of the Ce_1-xMn_x 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 Ce_0.95Mn_0.05 catalyst exhibited the best catalytic activity, achieving a high DMC yield of 6.44 mmol/g (120 °C, 6.5 MPa, 4 h).