Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over Ga2O3-CeO2-ZrO2 catalysts prepared by a single-step sol-gel method: Effect of acidity and basicity of the catalysts

XGa2O3-CeO2-ZrO2 (X=0, 1, 3, 5, 7, and 9) catalysts were prepared by a single-step sol-gel method with a variation of Ga2O3 content (X, wt%) for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The ratio of cerium oxide:zirconium oxide in the XGa2O3-CeO2-ZrO2 catalysts was fixed to be Ce0.6Zr0.4O2. Effect of acidity and basicity of XGa2O3-CeO2-ZrO2 on the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide was investigated using NH3-TPD and CO2-TPD experiments, respectively. Experimental results revealed that both acidity and basicity of the catalysts played important roles in determining the catalytic performance in the reaction. The amount of dimethyl carbonate increased with increasing both acidity and basicity of the catalyst. Among the catalysts tested, 3Ga2O3-CeO2-ZrO2, which retained the largest acidity and basicity, exhibited the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.