Study On The Synthesis Of Glycerol Carbonate From Glycerol By La₂O₂CO₃ Based Catalyst

Biodiesel has similar physical and chemical properties with petrochemical diesel. Biodiesel can be recycle used, biodegradable, non-toxic and its these excellent features make it become the best choice to replace petroleum diesel. While during the process of biodiesel industry, glycerol produced a lot as a byproduct. In order to maintain the balance of the glycerol existing market, improve the added value of glycerol and promote the development of biodiesel industry, many researchers focus on the study of value-added glycerol derivatives. And glycerol carbonate is one of the most attractive glycerol derivatives. In this study, pure La2O2CO3 catalyst and Ni, Cu supported Ni Cu/La2O2CO3 catalysts were prepared via precipitation method and impregnation method, respectively. They were used in the synthesis of glycerol carbonate from glycerol and urea, and the catalysts showed good performance. The structure properties of the as-prepared catalysts were studied by X-ray diffraction(XRD), Scanning electron microscope(SEM), transmission electron microscopy(TEM), Brunauer, Emmett and Teller method analyses(BET), X-ray photoelectron spectroscopy(XPS), temperature programmed desorption(TPD) and so on. The optimum reaction conditions for synthesis of glycerol carbonate were studied as well. The structure-activity relationship was investigated preliminarily.The catalysis results of pure La2O2CO3 catalyst prepared via precipitation method showed that: when the reaction temperature was 145 ?C, the ratio of glycerol to urea was 1:1, the reaction time was 1 h, catalyst loading was 3%(respect to glycerol), the conversion of glycerol was 83.69% with 83.74% selectivity to glycerol carbonate. The turnover frequency(TOF) of the catalyst in this reaction was 304 mmol/g·h. It gives high catalytic activity.Ni, Cu supported Ni Cu/La2O2CO3 catalyst was prepared through impregnation method to improve the catalytic activity of the La-based catalyst. When the loading of Cu and Ni was 10%, the reaction conditions were the same as the above, except the catalyst loading. The dosage of supported Ni Cu/La2O2CO3 was 0.67%(respect to glycerol), and the conversion of glycerol was 79.73%, the selectivity to glycerol carbonate was 79.75%. Ni Cu(10)/La2O2CO3’s TOF in the synthesis of glycerol carbonate is as much as 2547 mmol/g·h, which increased by more than 7 times.In this study, catalysts used in the synthesis of glycerol carbonate were successfully prepared. The catalysts exhibited good catalytic activity and stability and there is an important guidance for the catalytic conversion of glycerol.