Effect of acid–base properties of H 3PW 12O 40/Ce xTi 1− xO 2 catalysts on the direct synthesis of dimethyl carbonate from methanol and carbon dioxide: A TPD study of H 3PW 12O 40/Ce xTi 1− xO 2 catalysts

Abstract

H 3PW 12O 40/Ce x Ti 1− x O 2 catalysts were prepared by a sol–gel method, and were applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The acid and base properties of H 3PW 12O 40/Ce x Ti 1− x O 2 catalysts were measured by NH 3-TPD and CO 2-TPD experiments, respectively, to correlate the catalytic activities with the acid and base properties of H 3PW 12O 40/Ce x Ti 1− x O 2. In the direct synthesis of dimethyl carbonate from methanol and carbon dioxide, the catalytic activity of H 3PW 12O 40/Ce x Ti 1− x O 2 was superior to the corresponding Ce x Ti 1− x O 2. The catalytic performance of H 3PW 12O 40/Ce x Ti 1− x O 2 showed a volcano-shaped curve with respect to cerium content. The catalytic activity of H 3PW 12O 40/Ce x Ti 1− x O 2 increased with increasing acidity (acid amount) and with increasing basicity (base amount) of the catalyst. Among the catalysts tested, H 3PW 12O 40/Ce 0.1Ti 0.9O 2 with the largest acidity and basicity showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide.