以尿素和甲醇为原料合成碳酸二甲酯是煤化工产业链的重要延伸，可提高煤化工产品的附加值。采用1,2-丙二醇为循环剂改善该工艺的反应效果。首先在反应精馏装置上，对Zn-Al氧化物催化尿素和1,2-丙二醇合成碳酸丙烯酯反应及Ca-Al氧化物催化碳酸丙烯酯与甲醇酯交换合成碳酸二甲酯2个分步反应进行了考察，碳酸丙烯酯和碳酸二甲酯的收率最高分别为82.4%和98.1%。在此基础上，实现了以1,2-丙二醇为循环剂的尿素醇解合成碳酸二甲酯催化反应精馏过程，考察了操作条件的影响。在尿素与甲醇进料物质的量比为17、尿素与甲醇混合液的液时空速为0.5 h-1条件下，碳酸二甲酯收率达到最高，为58.2%。

Synthesis of dimethyl carbonate via urea and methanol is an important extension of the coal chemical industry chain,which can increase the added value of the coal chemical products. In this paper,propylene glycol was used as a circulating agent to intensify this reaction process. First,the two reactions,urea reacting with propylene glycol to propylene carbonate catalyzed by Zn-Al oxide and transesterification of propylene carbonate with methanol to dimethyl carbonate over Ca-Al oxide,were investigated in a reactive distillation column. The highest yields of propylene carbonate and dimethyl carbonate were 82.4% and 98.1%,respectively. Based on these experimental results,the catalytic distillation process of urea alcoholysis to dimethyl carbonate intensified by a circulating agent propylene glycol was realized,and the influence of reaction conditions was studied. Under the reaction conditions of a feed molar ratio of urea to methanol of 17,and a liquid hourly space velocity of the raw mixture of 0.5 h-1,the dimethyl carbonate yield reaches the highest of 58.2%.

0 引言

1 试验部分

   1.1 催化剂制备

   1.2 反应操作过程

   1.3 产物分析

2 结果与讨论

   2.1 尿素与PG醇解合成PC反应

   2.2 PC与甲醇酯交换反应合成DMC反应

   2.3 以PG为循环剂的尿素醇解合成DMC反应

3 结论