Separation Of Binary Azeotrope Methanol-Acetonitrile By Batch Extractive Distillation

Methanol and acetonitrile are commonly used raw material in organic synthesis,meanwhile, they are very versatile solvent for chemical and pharmaceutical industry.However, methanol and acetonitrile will be formed azeotrope at atmospheric pressure.The azeotropic temperature is63.45℃and the azeotrope contains81wt%ofmethanol and19wt%of acetonitrile. The traditional distillation method is not able toseparate the mixture. Therefore, we choose appropriate extraction distillation solventand research on the extraction distillation process for the azeotrope in this paperthrough the study of methanol/acetonitrile azeotrope nature.This paper uses ChemCAD software and choses Wilson model to simulatemethanol/acetonitrile binary vapor-liquid balance and the binary vapor-liquid balanceusing DMF or aniline as extraction distillation solvent. Through the comparsion of theexperimental data and simulation data, the extaction distillation process is veryfied tobe feasible.DMF and aniline are chosen as the extaction distillation solvent for the separationof methanol/acetonitrile binary azeotrope after the qualitative coarse selection and thenarrowing of range of optional solvent. Through the experiment it shows that anilineand DMF can make methanol/acetonitrile azeotropic phenomenon borke and itsazeotropic point disapper. Based on the comparsion and analysis of simulation resultsand experimental results, we can get thet the suitable solvent mass ratio of DMF3:1and the suitable solvent mass ratio of aniline is2.5:1.The batch extractive distillation is used to separate methanol/acetonitrile binaryazeotrope in this paper. The theortical plate number of the packing tower in theexperiments is33which including3plates for the purify recovery section and30plates for the extraction rectification section. The reflux ratio is4. When DMF is theextractive distillation solvent and the solvent ratio is3:1, the concentration of the lightcomponent at the top of the tower is0.9576. And when aniline is used as the solventand the solvent ratio is2.5:1, the concentration of the top product is0.9897. Whenaniline is the solvent, the concentration of the top product methanol is five percenthigher than that when DMF is the solvent. Considering Energy and raw material costs, aniline is more appropriate than DMF to be the extractive distillation solvent.However, in the case of the top product concentration is not high in need, it isfavorable to reduce the whole operation time as DMF is the extractive distillationsolvent. is favorable. So we should comprehensively considerate of the pros and consof the two kinds of solvents and choose more appropriate extractive distillationsolvent.In this article, the ChemCAD software is used to simulate the bactch extractivedistillation separation process for methanol/acetonitrile azeotrope.The simulation datacoincides well with the experimental.