填料塔中酯交换合成碳酸二甲酯工艺研究

Synthesis of DMC by transesterification in packed tower

以甲醇和碳酸丙烯酯为原料,研究了在填料塔中通过酯交换反应合成碳酸二甲酯的工艺,考察了原料配比、催化剂种类和用量、回流比等因素对碳酸二甲酯产率的影响。结果表明,较好的反应条件为甲醇和碳酸丙烯酯摩尔比为5∶1,加入催化剂NaOH的量为原料总质量的2%,在70℃时反应1 h,回流比为5,DMC产率可达43.6%;产物分离阶段,以正己烷为共沸剂,共沸精馏分离了甲醇和碳酸二甲酯共沸物,当正己烷用量为甲醇体积的350%、回流比为5时,DMC分离纯度高达95.78%。

The synthesis of dimethyl carbonate by transesterification of methanol and propylene carbonate was studied in the packed tower. The influences of raw material proportion, catalyst types and amounts, and reflux ratio on the yield of DMC were investigated. The optimal conditions are shown as follows ：5：1 molar ratio of methanol and propylene carbonate,NaOH as the catalyst and 2% of the total mass of the raw material, lh of reaction time at 70℃ ,5 of reflux ratio. The yield of DMC can reach 43.6%. The azeotrope mixture of methanol and dimethyl carbonate is separated by azeotropic distillation with hexane as the entrainer. The results show that when hexane is 350% of the amount of methanol （v） and reflux ratio is 5 ,the purity of DMC can reach up to 95.78%.