N,N-二甲基乙酰胺萃取精馏分离苯乙烯的工艺研究

利用流程模拟与小试试验相结合的方法进行了以N,N-二甲基乙酰胺（DMAC）为溶剂的裂解C8馏分萃取精馏分离苯乙烯工艺研究。采用流程模拟考察了溶剂比、回流比、溶剂进料板位置和溶剂进料温度对苯乙烯产品纯度和收率的影响规律，结果表明：以DMAC为溶剂，在进料位置为第11～13块塔板、溶剂比为3.8～4.2、回流比为3.1～3.3、溶剂进料温度为45～50 ℃的条件下萃取精馏所得苯乙烯产品的纯度可达99.8%以上，苯乙烯回收率达98.5%以上。小试试验的各项数据与流程模拟结果吻合，证明流程模拟系统可靠、结果可信。与以环丁砜（SUL）为溶剂的萃取精馏工艺相比，该工艺塔釜操作温度更低，只有113 ℃，有利于减少苯乙烯聚合反应的发生，从而利于装置长周期稳定运行。

STUDY OF SEPARATION OF STYRENE BY EXTRACTIVE DISTILLATION WITH N,N-DIMETHYLACETAMIDE SOLVENT

The separation of styrene from pyrolysis C8 fraction by extractive distillation, using N,N-dimethylacetamide as solvent, was studied by process simulation and pilot test. The effects of solvent ratio, reflux ratio, plate position of solvent feed and temperature on the purity and yield of styrene were investigated. The results showed that the styrene product purity can reach more than 99.8%，styrene recovery rate of 98.5% or more at the conditions of the feed plate position in the range of the 11th to 13th, the solvent ratio of 3.8-4.2, the reflux ratio 3.1-3.3, the solvent temperature 45-50 ℃. The pilot test results are consistent with the process simulation, proving that the process simulation system is reliable. Compared with the extraction distillation process by using sulfolane solvent, the operating temperature of the tower using N,N – dimethylacetamide solvent is only 113 ℃, beneficial to the long operation of the device.