The Vapor-liquid Equilibrium And Extractive Distillation Separation Of The N-Butanol And Chlorobenzene System

N-butanol is often used as raw material or additive to produce a variety of resins and coatings,and chlorobenzene is often used as solvent in these products.It is worthy to concern that how to recycle the solvent from waste liquid mixture.However,n-butanol and chlorobenzene can form minimum azeotrope at atmospheric pressure,we can hardly separate them by conventional distillation.If extractive distillation is to be used to separate the binary system,the VLE data of extractive entrainer with the two components are needed.In this paper,isobaric vapor-liquid equilibrium at atmospheric pressure was studied.Firstly,VLE data of five binary systems(n-butanol + chlorobenzene,n-butanol + acetophenone,chlorobenzene + acetophenone,n-butanol + dimethyl sulfoxide(DMSO),chlorobenzene + DMSO)were measured at 101.33 kPa by using vapor phase condensation circulating method.And then,all of the measured VLE values were checked by the area method proposed by Herington and the point-to-point method of Van Ness.Furthermore,the experimental VLE data were correlated by Wilson,NRTL and UNIQUAC activity coefficient models,respectively.Finally,the VLE data of two ternary systems(n-butanol + chlorobenzene + acetophenone,n-butanol + chlorobenzene + DMSO)were calculated by the UNIQUAC model parameters which were correlated by the VLE data of binary systems,respectively.The results indicate that all of the measured VLE data passed thermodynamic consistency test and the values calculated by all these three models agree well with the experimental data.Acetophenone as well as DMSO can change the relative volatility of n-butanol and chlorobenzene,and acetophenone has a better performance.Then on this basis,continuous extractive distillation process with two towers using acetophenone as the extractive entrainer was applied to separate n-butanol and chlorobenzene by using the experimental data.At first,the steady-state design for the whole process was proposed by using the chemical process simulation software Aspen Plus,and then a global economic optimization was carried out using the total annual cost(TAC)as the objective function(make sure the purity and yield of products were more than 99.9%).Finally,the dynamic performance of the optimized process was investigated by using Aspen Dynamics.The simulation results indicate that acetophenone can separate the azeotropic system of n-butanol and chlorobenzene effectively as an extractive entrainer,and the extractive distillation process is economical efficiency and controllable.