Direct Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide over Ga2O3/Ce0.6Zr0.4O2 Catalysts: Effect of Acidity and Basicity of the Catalysts

Ce X Zr 1− X O 2 catalysts with different cerium content ( X ) ( X = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol–gel method for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Among these catalysts, Ce 0.6 Zr 0.4 O 2 was found to show the best catalytic performance. In order to enhance the acidity and basicity of Ce 0.6 Zr 0.4 O 2 catalyst, Ga 2 O 3 was supported on Ce 0.6 Zr 0.4 O 2 ( X Ga 2 O 3 /Ce 0.6 Zr 0.4 O 2 ( X = 1, 5, 10, and 15)) by an incipient wetness impregnation method with a variation of Ga 2 O 3 content ( X , wt%). Effect of acidity and basicity of Ga 2 O 3 /Ce 0.6 Zr 0.4 O 2 on the catalytic performance in the direct synthesis of dimethyl carbonate was investigated using NH 3 -TPD and CO 2 -TPD experiments. Experimental results revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Large acidity and basicity of the catalyst facilitated the formation of dimethyl carbonate. The amount of dimethyl carbonate produced over X Ga 2 O 3 /Ce 0.6 Zr 0.4 O 2 catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, 5Ga 2 O 3 /Ce 0.6 Zr 0.4 O 2 , which retained the largest acidity and basicity, showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Graphical Abstract In the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over Ga 2 O 3 /Ce 0.6 Zr 0.4 O 2 catalysts, the amount of DMC showed a volcano-shaped curve with respect to Ga 2 O 3 content. The amount of DMC increased with increasing both acidity and basicity of the catalysts