离子液体催化粗甘油合成碳酸甘油酯

SYNTHESIS OF GLYCEROL CARBONATE USING IONIC LIQUIDS CATALYSTS

合成一系列酸性、碱性和中性离子液体,采用核磁共振、红外光谱分析法进行表征验证,并用于催化粗甘油和碳酸二甲酯合成甘油碳酸酯,考察物质的量之比、反应温度、反应时间和离子液体用量对反应的影响及离子液体的稳定性。结果表明,碱性离子液体在碳酸甘油酯制备过程中表现优异,以[Bmim]Im离子液体为催化剂时,在n(碳酸二甲酯)∶n(粗甘油)=3∶1,反应温度为80℃,反应时间为70 min,离子液体(催化剂)用量为粗甘油质量12%的条件下,粗甘油转化率为96%,碳酸甘油酯选择性和收率分别为97%和94%,该离子液体回收重复利用8次,粗甘油转化率仍可达85%,碳酸甘油酯选择性可近90%。

In this study,a series of acidic,basic and neutral ionic liquids were synthesized by two-step method.Their structures were characterized by FT-IR spectra,NMR.The detection and analysis showed that their structures were in accordance with their theoretical structure.These synthetic ionic liquids were then used as catalysts to catalyze the synthesis of glycerol and dimethyl carbonate into glycerol carbonate.The effects of molar ratio of glycerol to dimethyl carbonate,reaction temperature,reaction time and ionic liquid dosage on transesterification and stability of the ionic liquid were investigated.The results showed that the basic ionic liquids have higher catalytic activity compared with acidic,neutral ionic liquids and inorganic basic catalysts in the transesterification.With [Bmim]Im ionic liquid as the catalyst,when w(dimethyl carbonate):w(glycerin) was 3:1,the reaction temperature was 80℃,reaction time was 70 minutes,and ionic liquid(catalyst) dosage was 12% of the glycerol mass,glycerin conversion rate was 96%,and the selectivity and yield of glycerol carbonate was 97% and 94%,respectively.After recycling ionic liquid for eight times,glycerin conversion rate can still reach 85%,and the selectivity of glycerol carbonate can reach approximately 90%.The above study reveals that synthetic basic ionic liquid was an ideal green catalyst in esterification reaction.