Preparation of mesoporous CaO-ZrO2 catalysts without template for the continuous synthesis of glycerol carbonate in a fixed-bed reactor

摘要

Recently, transformation of glycerol into glycerol carbonate (GLC) has been of critical importance. Although traditional Ca-based catalysts present high activity for the GLC synthesis, their industrial applications are hindered by the leaching of Ca2+. Here, a series of mesoporous CaO-ZrO2 with high surface area were obtained without template. CO2 temperature-programmed desorption displayed that the basic properties of the catalysts can be controlled by the content of Ca dopant. Importantly, Ca2+ can be introduced into t-ZrO2 lattice, resulting in the formation of a solid solution structure. Based on systematic experiments, a correlation between their basic properties and catalytic behavior was explained. Under the optimized conditions, the catalyst with a certain ratio of Ca: Zr = 0.6: 1 showed an excellent performance with a 97% glycerol conversion and a 93% selectivity of GLC. Furthermore, the solid solution structure rendered this catalyst high resistance to reactant flushing in a fixed-bed, without leaching of active sites.