萃取精馏分离乙腈-正丙醇的研究

采用萃取精馏的方法分离乙腈-正丙醇的共沸物系。首先利用溶剂选择原理和UNIFAC基团贡献法选出N-甲基吡咯烷酮作为萃取精馏的萃取剂,同时采用NRTL模型对常压下乙腈-正丙醇物系和加入萃取剂N-甲基吡咯烷酮后的汽液平衡进行模拟和实验验证,模拟结果与实验数据吻合较好。然后通过间歇萃取精馏实验进一步考察所选萃取剂的分离效果。结果表明,N-甲基吡咯烷酮能够打破共沸,有效分离乙腈-正丙醇共沸物系。采用有28块理论板的填料塔,萃取剂进料位置为第4块板,溶剂比为1.0,回流比为3,可以从塔顶得到质量分数为98.6%的乙腈产品。最后,用Aspen Plus软件对乙腈-正丙醇物系的连续萃取精馏流程进行了模拟,得出的参数为进一步的工业应用奠定基础。

Separation of Acetonitrile-1-Propanol by Extractive Distillation

This paper studies on separation of acetonitrile-1-propanol by extractive distillation. First,Nmethyl pyrrolidone was chosen as the solvent by the basic selection rules and the UNIFAC group contribution method. The simulation of vapor-liquid equilibrium using NRTL model for acetonitrile-1-propanol with and without N-methyl pyrrolidone under atmospheric pressure and vapor-liquid equilibrium experiment were performed and the simulation results agreed well with the experimental data. Then the batch extractive distillation experiment was performed to investigate the effectiveness of the selected solvent.The results show that N-methyl pyrrolidone as solvent can break the azeotrope of acetonitrile-1-propanol system and separate the azeotrope effectively. The batch extractive distillation was carried out in a packed column of 28 theoretical plates and the extractive solvent flowed inside on the fourth plate. With the reflux ratio of 3 and the solvent mole ratio of 1∶ 1,the product mass fraction of acetonitrile reaches 98. 6%.Finally,Aspen Plus was used to simulate the continuous extractive distillation process and the technological parameters can provide some reference basis for the industrial production.