Dimethyl carbonate synthesis via transesterification of propylene carbonate with methanol by ceria-zinc catalysts: Role of catalyst support and reaction parameters

Ceria and zinc oxide catalyst were impregnated onto various oxide supports, namely Al₂O₃, TiO₂ and SiO₂, individually by deposition-coprecipitation method. The synthesized catalysts (CZA, CZS and CZT having supports Al₂O₃, TiO₂ and SiO₂, respectively) were characterized by X-ray diffraction (XRD), NH₃- and CO₂-temperature programmed desorption (TPD) and N2 adsorption. These catalysts were used for synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate in a batch reactor. CZS was found to have larger average grain size as compared to CZA and CZT. Composite oxides (catalysts) were found to contain individual phases of ZnO, CeO₂ and some spinel forms of Zn, Ce along with their supports. CZS having highest basicity and surface area showed better catalytic activity as compared to CZA and CZT. Effect of reaction temperature and methanol/PC molar ratio on DMC yield was studied and a reaction mechanism has been discussed. Maximum DMC yield of 77% was observed with CZS catalyst at 170 .deg. C with methanol/PC molar ratio of 10.