The Vapor-liquid Equilibrium And Azeotropic Distillation Of The System Benzonitrile-indene

Both indene and benzonitrile are very important raw materials in chemical engineering.Indene is widely used in biology,chemical engineering and pharmacy fields.Benzonitrile is widely used in pharmaceuticals,pesticides,dyestuff,rubber and many other fields.Indene mainly comes from an indene-containing coal tar fraction.After the purification of indene from this fraction,the majority of the impurity in the fraction is benzonitrile.Due to the closing boiling points,indene and benzonitrile can hardly be separated by conventional distillation.What's more,vapor-liquid equilibrium(VLE)data of this binary system is not found in literature.All of these have a bad effect on the theoretical study and industrial manufacture of the benzonitrile-indene system.In this work,first,VLE data of benzonitrile-indene binary system was measured at 22.0,32.0 and 42.0kPa using a vapor-liquid equilibrium recirculating still.The Herington area test and Van ness differential test were applied to check the thermodynamic consistency.The experimental VLE data were correlated with Wilson,NRTL and UNIQUAC activity coefficient models,and the binary interaction parameters of these three models were calculated using Matlab software.The results show that all these three models agree well with the experimental data.Furthermore,the processes of homogenous pressure-swing azeotropic distillation using phenol as entrainer and heterogenous azeotropic distillation using glycol as entrainer were analyzed to be feasible.Then the two processes were simulated by Aspen plus v7.2 and the steady-state design were applied.After that,a global economic optimization was carried out using the total annual cost(TAC)as objective function.By economic optimization,the optimal parameters of the process of homogenous pressure-swing azeotropic distillation using phenol as entrainer and heterogenous azeotropic distillation using glycol as entrainer were obtained.The results of optimization were discussed and analyzed.It is found that at the same conditions of feedstock,product purity and target product yield,the process of heterogenous azeotropic distillation using glycol as entrainer has advantages in energy consumption and fixed investment compared with the process of homogenous pressure-swing azeotropic distillation using phenol as entrainer.And the process of heterogenous azeotropic distillation is better than the process of homogenous pressure-swing azeotropic distillation in TAC.