Synthesis Of Glycerol Carbonate By Microwave Assisted Reaction Of Glycerol And Urea

With the rapid development of biodiesel industry,a large number of by-products glycerol is seriously overabundant,which affects the economical production of biodiesel.Therefore,the development of new industrial uses of glycerol is very important.Glycerol carbonate(GC),as one of the high value-added derivatives of glycerol,has attracted more and more attention.Among them,the method of synthesizing GC from glycerol and urea has attracted wide attention because of its advantages such as cheap raw materials,environmentally friendly and highly efficient atomic economy.Microwave has the characteristics of cleanliness,high efficiency,low energy consumption and less pollution.It is widely used in organic synthesis,preparation of functional materials and other fields.In this study,microwave assisted technology was applied to the preparation of modified hydrotalcite and the reaction of glycerol with urea.For the first time,the microwave method was used to quickly promote the ion modification of hydrotalcite,and a zinc modified hydrotalcite catalyst was prepared.The structure and composition of the catalyst were characterized by FT-IR,XRD,XPS and XRF.The effects of catalysts with different modification times on carbonylation of glycerol were investigated.The results showed that the catalytic effect of zinc modified 6 h catalyst was the best.Under the condition of microwave-assisted heating at 150 °C,the conversion of glycerol was 85.3 % after 2 h reaction,and the selectivity of glycerol carbonate was up to 98.5 %.This article examines the effect of the calcination temperature of the catalyst on the reaction of the synthetic glycerol carbonate.The structure and composition of the catalyst were characterized by FT-IR,XRD,XPS and XRF,and the catalytic activity of the catalyst at different calcination temperatures was evaluated.The results show that the catalytic performance is related to the calcination temperature of the catalyst.When catalyzed by calcined catalyst at 900 °C,the feed ratio of glycerol to urea was 1:1,microwave-assisted heating was carried out at 150 °C for 1.5 h,the conversion of glycerol was 88.6 %,and the selectivity of glycerol carbonate was as high as 94.9 %.Better catalytic performance is maintained after 4 cycles.