Research For Synthesis Of Glycerol Carbonate By Transesterification From Glycerol And Dimethyl Carbonate With The CaO-based Catalyst

Selection of catalyst is the key to the successful transesterification of glycerol anddimethyl carbonate. CaO is the ideal catalyst for its high activity, wide raw materialsources and low cost. But CaO is easy to deactivate in the transesterification of glyceroland dimethyl carbonate. Therefore, it is very important to analyze the deactivationmechanism and find a way to improve stability and activity of CaO catalyst.Firstly, a series of heterogeneous KNO3/CaO catalysts are prepared by theimpregnation method and used for the synthesis of glycerol carbonate from glycerol anddimethyl carbonate. It is found that the basic property of the KNO3/CaO depends on theloading amount of KNO3and calcination temperature. There is an obvious relationbetween the catalytic activity of the KNO3/CaO catalyst and the basic strength and theamount of basic sites. The KNO3/CaO(15%,700) with KNO3loading amount of15%calcined at700℃, exhibits the highest catalytic activity and stability. Under the dimethylcarbonate/glycerol molar ratio of3.0, reaction temperature of70℃, and reaction time of2h, the glycerol conversion for the fresh KNO3/CaO(15%,700) catalyst can reach99.23%.At the fifth recycling, the glycerol conversion for the recovered KNO3/CaO(15%,700)can reach94.95%, which is far higher than that of CaO catalyst. A plausible deactivationmechanism about KNO3/CaO catalyst is also proposed.Secondly, this thesis provides a method for preparation of extruded CaO-basedcatalysts K2O/CaO/Al2O3and the catalysts are used for the synthesis of glycerol carbonatefrom glycerol and dimethyl carbonate. With the calcination temperature of800℃,reaction temperature of80℃, DMC/GL molar ratio of3:1, CaO/GL molar ratio of0.1, theconversion of GL is98.54%for the first time, and as high as90.5%at the fifth recycling.K2O/CaO/Al2O3(0.15,0.6,0.15) catalysts in the synthesis of glycerol carbonate not onlyhas good catalytic activity, stability, and good mechanical strength, but also it is easy separated from the reaction system. So, the catalyst can be used for the industrial processfor producing glycerol carbonate.