Vapor-Liquid Equilibrium and Separation Process of Ethylene Glycol and 1,2-Butanediol Mixture

Development of the process producing ethylene glycol (EG) from the syn-gas, inorder to substitute the conventional route from petroleum, has risen to a new level.The route for EG manufacturing based on syngas can be divided into two steps:dimethyl oxalate (DMO) is synthesized by carbonization coupling of CO, then turnedto EG by hydrogenation. In the process of excess hydrogenation1,2-butanediol(1,2-BDO) is generated as by-product. The separation of EG withby-product 1,2-butanediol is of great significance. However, so far to our knowledge,vapor-liquid equilibrium relation of EG and 1,2-BDO, the foundation for distillationprocess design, is unavailable in the published literatures.In this work, Vapor-Liquid Equilibrium data of ethylene glycol and1,2-butanediol were measured by an improved Ellis vapor-liquid equilibrium(VLE)pot at atmosphere pressure. All the experimental VLE data have been tested by theHerington method showing that the experimental data conform to demand of thermodynamicconsistency. The Vapor-Liquid Equilibrium data were correlated by Wilson and NRTLequation with the help of software Aspen Plus, obtaining the model parameters and thecomposition at the azeotropic point.Wilson model The max relative deviation of calculated data and that of experimental data are0.89% by Wilson and 0.74% by NRTL with the average of 0.19% and 0.18%separately. The azeotropic point is 465.91K with the 47.0% of EG and 53.0%1,2-BDO.The end of this study, using Pro/II chemical industry simulation software whosedatabase has been complemented with simulated data and by setting separation effectof EG-1, 2-BDO binary system, provides some possible designing parameters ofdistillation which maybe helpful to carry on further study for industrial production.The product can be separated with three columns. According to the study of theseparation of EG and 1,2-BDO, they can be separated by distillation with certainamount of trays and by increasing reflux ratio purified EG can be accumulated at thebottom. The selection of entrainer for separation of the mixture on the top has alsobeen discussed providing reference for further study.