The Study Of Glycerol Catalyzed By Metal Oxide Synthesis Of Glycerol Carbonate

Biodiesel as a renewable energy has developed rapidly in recent years.It is important to convert glycerol into high value-added products.The carbonylation reaction of glycerol and urea and transesterification reaction of glycerol and dimethyl carbonate or diethyl carbonate are used to synthesis glycerol carbonate.The high yield of glycerol carbonate is obtained by transesterification.Moreover,the preparation process of transesterification is simple and easy to operate.In this paper,two methods are used to prepare glycerol carbonate.The quantitative analysis method was applied for glycerol and glycerol carbonate with high boiling point.A qualitative and quantitative analysis method of glycerol and glycerol carbonate by SE-54 capillary column gas chromatography with FID detector and using tetraglycol as internal standard was introduced.Temperature programmed from 60 ? to 260 ? and using of silyl reagent was adopted in the analysis.The silyl reagent was used to reduce the boiling point of glycerol and glycerol carbonate.The results showed that glycerol and glycerol carbonate had a good linear correlation.The correlation coefficient were 0.999 and 0.997.Values of average recoveries and the relative standard deviations?n=6?found were in the range of 99.4%-100.2% and 0.09%-1.2%,respectively.This method had the good accuracy and precision.According to the characteristics of carbonylation reaction,a novel porous ZnO catalyst with acid and base center was designed to catalysis glycerol and urea to synthesis glycerol carbonate.The catalyst was prepared via the glycerol approach and glycerol was also used as a reactant in the carbonylation reaction to obtain glycerol carbonate.The highest glycerol carbonate yield reached 85.97% of ZnO from zinc glycerolate under the optimal reaction conditions of 5.0 wt% of catalyst,1:1.5 molar ratio of glycerol to urea and reacting at 140 ? for 6 h under 1 kPa.The catalyst maintained excellent yield with 70.85% after 6 cycles with almost no loss of catalytic activity.The ZnO catalyst with appropriate acid and base properties was highly active,highly recyclable,remarkably stable,and environmental friendly for industrial applications.The transesterification reaction is used to achieve high yield of glyceryl carbonate.The solid base catalyst is often applied in the transesterification reaction.The catalyst MgO-Al₂O₃-SrCO₃ with high activity was obtained by adding Mg element to reduce the agglomeration of the catalyst and increase the amount of base and basicity of the catalyst.The catalyst was applied for transesterification.The study revealed that the yield of glycerol carbonate attained 98.97% when the reaction temperature was 85 ?,the catalyst loading was 5.0 wt.%,the molar ratio of DMC/glycerol was 5:1 and the reaction time was 1.5 h.The catalyst still showed excellent yield with87.95% without significantly weaking.An excellent pore structure can improve the rate of transesterification.To improve morphology of catalyst need to pore-expanding agent PEG20000.Fish-shaped material endowed its high specific surface area which promote the diffusion of active sites and accelerate the rate of reaction.A thorough study on the influence of the La/PEG20000 molar ratio and different molecular weight of PEG was performed by transesterification reaction.The optimum routes were as follows: the 5:1 molar ratio of DMC/glycerol,5.0 wt.% of the catalyst and reacting at 85 ? for 0.5 h.The yield of glycerol carbonate maintained 92.05% after 6 cycles.It showed that the catalyst had the excellent reusability.The magnetic catalyst can be rapidly separated from the reactants by the addition of magnetic fields for industrial production.The magnetic core Fe₃O₄ was prepared from Fe₂O₃ using active carbon as reductant under N2 atmosphere and magnetic heterogeneous catalyst??CaO-MgO?@Fe₃O₄/C?was prepared by co-precipitation methods.The?CaO-MgO?@Fe₃O₄/C was investigated in the transesterification of glycerol with DMC.The TEM indicated that Fe₃O₄/C was well wrapped by?CaO-MgO?.The effects of different reaction conditions on the yield of glycerol carbonate were investigated.The catalyst still had steady catalytic performance after 6 cycles with a high glycerol carbonate yield of 94.45%.