Acidic–Basic Bifunctional Magnetic Mesoporous CoFe2O4@(CaO–ZnO) for the Synthesis of Glycerol Carbonate

Abstract

Magnetic mesoporous CoFe2O4@(CaO–ZnO) exhibited good catalytic activity in the transesterification of glycerol and dimethyl carbonate to yield glycerol carbonate. The glycerol conversion of 97.7% and glycerol carbonate yield of 96.9% could be obtained in this reaction system under the optimized reaction conditions. CoFe2O4@(CaO–ZnO) was characterized by a series of techniques including TPD, XRD, SEM, TEM, EDS, VSM and BET to evaluate the physico-chemical properties of the catalyst. It was demonstrated that the interaction of acid–base sites improved the catalysis performance of CoFe2O4@(CaO–ZnO): the strong basic sites were beneficial to the activation of glycerol to glyceroxide anion which could increase glycerol conversion, and the acid site contributes to the carbonyl activation of dimethyl carbonate, converts glyceroxide anion to glycerol carbonate, and improves the selectivity of glycerol carbonate. Meanwhile, the solid–liquid separation process after reaction would be simplified significantly considering CoFe2O4@(CaO–ZnO) could be easily separated from the reaction mixture under magnetic action. Acidic–basic bifunctional magnetic mesoporous CoFe2O4@(CaO–ZnO) was used as a solid base catalyst for the glycerol transesterification. Basic sites were beneficial to the activation of glycerol to glycerol oxygen anion to increase glycerol conversion and acidic sites were beneficial to carbonyl activation of DMC to increase glycerol carbonate selectivity. With magnetism, the solid base catalyst was easily recovered.