Development of a trapezoidal MgO catalyst for highly-efficient transesterification of glycerol and dimethyl carbonate

A series of micro-sized MgO catalysts with various morphologies have been prepared by varying the reaction temperature and stirring time during precipitation, and were investigated for the production of glycerol carbonate from the transesterification of glycerol with dimethyl carbonate. In contrast to other morphologies of MgO (e.g., rod-like, spherical, flower-like and nest-like), trapezoidal MgO demonstrated a superior performance with a yield of glycerol carbonate of more than 99%. Various techniques including N-2 physical adsorption, XRD, CO2 chemical adsorption and EDS revealed that the unique catalytic activity of trapezoidal MgO was related to its lower specific surface area, bigger crystallite size, weaker surface basicity and fewer Mg atom vacancies compared to the other morphologies of MgO. The experimental conditions (e.g., the catalyst amount, solvent, reaction temperature and molar ratio between glycerol and dimethyl carbonate) were also found to play crucial roles in determining the yield of glycerol carbonate. Furthermore, CO2-TPD profiles and FT-IR spectra indicated that the weak surface basic sites occurring at 150 degrees C and the CO32- stretching vibration around 1448 cm(-1) were responsible for the catalytic activity of the developed trapezoidal MgO in regeneration.