锌盐催化尿素和1,2-丙二醇合成碳酸丙烯酯

Synthesis of propylene carbonate from urea and 1,2-propylene glycerol over zinc salts

考察了各种锌盐催化尿素和1,2-丙二醇(PG)合成碳酸丙烯酯(PC)的催化性能。几种催化剂中,氯化锌具有最佳的催化性能。以氯化锌为模板催化剂,考察了反应条件如:反应温度、反应时间和催化剂用量对催化效果的影响。结果表明,在尿素3.0 g、PG 7.62 g、反应温度170℃、反应时间3 h、催化剂用量0.4 g时,PC收率可达到82.9%。傅里叶红外表征进一步说明,催化剂的催化活性与它们活化尿素分解为异氰酸的能力有关;然后,异氰酸与催化剂作用生成中间物种,在PG的作用下最终生成PC。最后,基于以上催化测试和表征结果,提出了尿素和PG反应合成PC可能的催化反应机理。

Various zinc salts were used as the catalysts for the synthesis of propylene carbonate（ PC） from urea and1,2-propylene glycerol（ PG）. Among these catalysts,Zn Cl2 presented the best catalytic performance. Besides,the effects of reaction conditions such as reaction temperature, reaction time and catalyst amounts on catalytic performance were explored over ZnCl2 as the model catalyst in the present work. It indicates that under the optimal reaction conditions of urea 3. 0 g,PG 7. 62 g,reaction temperature 170 ℃,reaction time 3 h,catalyst amount0. 4 g,PC yield can reach 82. 9%. FTIR characterization further reveals that the catalytic performances of these catalysts are related to their abilities of activation of urea decomposition into isocyanic acid. Some intermediate species are formed from interact of isocyanic acid and catalyst. PC is finally produced by PG reaction with these active species. In addition,a possible reaction mechanism was proposed on the basis of catalytic test and characterization results.