以苯胺为溶剂间歇萃取精馏分离甲醇-乙腈

Separation of methanol-acetonitrile by batch extractive distillation with aniline as solvent

提出和研究了以苯胺作为溶剂的甲醇-乙腈间歇萃取精馏分离工艺。根据溶剂极性相似相溶原理,结合ChemCAD软件模拟汽液平衡和汽液平衡实验确定苯胺为合适的溶剂。结果表明,不仅苯胺能够消除甲醇-乙腈物系的共沸现象,效果优于N,N-二甲基甲酰胺(DMF),而且可以采用Wilson模型对苯胺作为溶剂的甲醇-乙腈共沸物系汽液平衡进行模拟。通过实验考察了间歇萃取精馏的分离效果。采用有33块理论板的填料塔进行间歇萃取精馏甲醇-乙腈共沸混合物分离实验,其中净化回收段填料层3块理论板,萃取精馏段填料层30块理论板,回流比为4,苯胺作为溶剂,溶剂质量比为2.5∶1时,在塔顶得到产品甲醇质量分数为98.97%,高于DMF作为溶剂时的95.76%;表明苯胺更加适合作为萃取精馏分离甲醇-乙腈共沸物系的溶剂。

In this paper,aniline was proposed as the solvent for the separation of the azeotrope methanol-acetonitrile by batch extractive distillation and the process was studied.Aniline was selected as the suitable solvent on the basis of the law of similarity and dissolvability,combined with VLE simulation by ChemCAD software and the VLE experiments.The results show that aniline as the solvent could break the azeotrope and the effects of aniline were better than N,N-dimethylformamide（DMF）.The Wilson model was used in VLE simulation.The experiment on the separation of the azeotrope methanol and acetonitrile by batch extractive distillation was carried out with a packed column with 33 theoretical plates among which 3 theoretical plates are in rectifying and recovery section and 30 theoretical plates in extractive distillation section.With the reflux ratio of 4,and the solvent mass ratio of 2.5∶1,the product purity of methanol reaches 98.97%,which is higher than the value of 95.76% when DMF was used as the solvent.It indicates that the extractive distillation with aniline as solvent is more suitable for the separation of azeotrope methanol-acetonitrile.