异氰酸锌催化合成碳酸乙烯酯工艺

Synthesis of vinyl carbonate catalyzed by zinc isocyanate

文中以尿素和乙二醇为原料,以锌前驱体制备异氰酸锌催化剂,再利用其催化合成碳酸乙烯酯,提高尿素利用率和碳酸乙烯酯收率。通过对自制异氰酸锌催化剂的性能测试,不同锌化合物、催化剂用量、温度、反应压力等条件对碳酸乙烯酯收率影响的考察,确定以氯化锌为前驱体合成异氰酸锌,并确定最佳反应条件为催化剂用量为0.05 mol,尿素和乙二醇摩尔比为1.02∶1,反应温度为145℃,反应压力为5 kPa,尿素连续加料至反应液中。该工艺碳酸乙烯酯获得最高收率94%,尿素转化率大于99%。同时将推测的催化反应机理应用于反应条件的控制,降低了脱水副产物2-噁唑烷酮的收率,提高了尿素的利用率。

Urea and ethylene glycol were used as raw materials to prepare zinc isocyanate catalyst with zinc precursor,which was then used to catalyze the synthesis of vinyl carbonate,so as to improve the utilization rate of urea and the yield of vinyl carbonate.Through the performance test of the self-made zinc isocyanate catalyst,the investigation of the effects of different zinc compounds,catalyst amount,temperature,reaction pressure and other conditions on the yield of vinyl carbonate,it was determined that zinc isocyanate was synthesized with zinc chloride as the precursor,and the optimal reaction conditions were determined as follows:the catalyst amount was 5%,the molar ratio of urea and ethylene glycol was 1.02∶1,the reaction temperature was 145℃,the reaction pressure was 5 kPa,and urea was continuously added into the reaction solution.The highest yield of vinyl carbonate was 94%,and the urea conversion was more than 99%.At the same time,the speculated catalytic reaction mechanism was applied to the control of reaction conditions,reducing the yield of 2-oxazolidinone,a by-product of dehydration,and improving the utilization rate of urea.