Catalytic Performance of ZrO2 Prepared by Hydrothermal Method for Transesterification of Glycerol
ZrO2 catalysts were prepared by the hydrothermal method for catalyzing the synthesis of glycerol carbonate(GC)from the ester exchange reaction of glycerol(GLY)with dimethyl carbonate(DMC).The effect of calcination temperature on the catalytic performance was investigated,and the ZrO2 catalysts were characterized by powder X-ray diffraction(XRD),isothermal adsorption-desorption of N2,and temperature programmed desorption(TPD).The results show that the catalytic performance of ZrO2 catalysts is highly dependent on the density of strongly basic sites on their surfaces.At the calcination temperature of 600 ℃,the prepared ZrO2-600 catalysts have a high density of strongly basic sites on the surface;at the reaction temperature of 90 ℃ for 90 min,the GLY conversion is 96.1％and the GC selectivity is 86.2％.When the ZrO2 catalysts are used repeatedly for the third time,the GLY conversion and GC selectivity decrease significantly due to the decrease in the density of basic sites on the ZrO2 surface,pore collapse,and the dissolution of partial ZrO2 sample in DMC.
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