Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over transition metal oxide/Ce0.6Zr0.4O2 catalysts: Effect of acidity and basicity of the catalysts

Abstract

CeXZr1−XO2 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. Among these catalysts, Ce0.6Zr0.4O2 showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. To see the effect of acidity and basicity of transition metal oxide/Ce0.6Zr0.4O2 catalysts on the catalytic performance in the direct synthesis of dimethyl carbonate, MO/Ce0.6Zr0.4O2 (MO=Ga2O3, La2O3, Ni2O3, Fe2O3, Y2O3, Co3O4, and Al2O3) catalysts were prepared by an incipient wetness impregnation method. NH3-TPD and CO2-TPD experiments were carried out to measure acidity and basicity of the supported catalysts, respectively. 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. The amount of dimethyl carbonate produced over MO/Ce0.6Zr0.4O2 catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, Ga2O3/Ce0.6Zr0.4O2, which had the largest acidity and basicity, exhibited the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.