Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over H3PW12O40/CeXZr1-XO2 catalysts: Effect of acidity of the catalysts

CeXZr1-XO2 catalysts were prepared by a sol-gel method, and H3PW12O40/CeXZr1-XO2 catalysts were then prepared by an impregnation method. Both catalysts were applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide in a batch reactor. NH3-TPD experiments were carried out to investigate the effect of acidity on the catalytic performance of CeXZr1-XO2 and H3PW12O40/CeXZr1-XO2. Catalytic performance of CeXZr1-XO2 and H3PW12O40/CeXZr1-XO2 was closely related to the acidity of the catalysts. The amount of dimethyl carbonate produced over both CeXZr1-XO2 and H3PW12O40/CeXZr1-XO2 catalysts increased with increasing acidity of the catalysts. This indicates that acidity of the catalyst played a key role in determining the catalytic performance of CeXZr1-XO2 and H3PW12O40/CeXZr1-XO2 in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Catalytic activity of H3PW12O40/CeXZr1-XO2 was higher than that of the corresponding CeXZr1-XO2. The enhanced catalytic performance of H3PW12O40/CeXZr1-XO2 was attributed to the Bronsted acid sites provided by H3PW12O40.