Catalytic properties and structure of zirconia catalysts for direct synthesis of dimethyl carbonate from methanol and carbon dioxide

Selective synthesis of dimethyl carbonate from methanol and CO2 proceeded e ffectively on a zirconia catalyst prepared by the calcination of zirconium hydroxide at 673 K. The bulk of this zirconia had a mainly tetragonal struc ture which was determined by XRD. In contrast, near its surface the monocli nic phase was major and the tetragonal phase was minor, as determined by la ser Raman spectroscopy. But the ratio of the tetragonal phase to the monocl inic was higher on this zirconia catalyst than on other catalysts prepared at different calcination temperatures. The number of neighboring acid-base sites estimated by temperature-programmed desorption is suggested to be rel ated to the activity of dimethyl carbonate formation. (C) 2000 Academic Pre ss.