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 Ce_0.6Zr_0.4O₂. 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.