Effect of acid-base properties of H3PW12O40/CexTi1-xO2 catalysts on the direct synthesis of dimethyl carbonate from methanol and carbon dioxide:: A TPD study of H3PW12O40/CexTi1-xO2 catalysts

H3PW12O40/CexTi1-xO2 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 H3PW12O40/CexTi1-xO2 catalysts were measured by NH3-TPD and CO2-TPD experiments, respectively, to correlate the catalytic activities with the acid and base properties of H3PW12O40/CexTi1-xO2. In the direct synthesis of dimethyl carbonate from methanol and carbon dioxide, the catalytic activity of H3PW12O40/CexTi1-xO2 was superior to the corresponding CexTi1-xO2. The catalytic performance of H3PW12O40/CexTi1-xO2 showed a volcano-shaped curve with respect to cerium content. The catalytic activity of H3PW12O40/CexTi1-xO2 increased with increasing acidity (acid amount) and with increasing basicity (base amount) of the catalyst. Among the catalysts tested, H3PW12O40/Ce0.1Ti0.9O2 with the largest acidity and basicity showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. (c) 2007 Elsevier B.V. All rights reserved.