Correlation and Prediction of Vapor-Liquid Equilibrium for the Propylene Oxide-Ethanol-Water Ternary System
|School||Changchun University of|
|Keywords||Propylene oxide NRTL equation Wilson equation UNIFAC equation Vap-or-Liquid Equilibrium|
Epoxy propane (PO) is the third propylene derivatives after polypropylene, acrylonitrile, which used in the productions of polyether polyols, propylene glycol and various kinds of non ionic surface active agent. PO can been obtained by an epoxidation of propylene, and the method of Hydrogen peroxide preparation epoxy propane (HPPO) only obtaining PO, water and solvent, which studied by Dow chemical and BASF being reward Greener Synthetic Pathways Award. The BASF products PO with methanol as solvent, and Zhang Qiurong etc. with isopropyl alcohol. However, methanol and isopropyl alcohol is toxic, and the price is high; So PO was producted using ethanol as solvent is more promising than methanol or isopropyl alcohol.Propylene oxide is widely applied, and it is essential to separate PO from productions mixture. However, the vapor-liquid equilibrium (VLE) data of PO systems are very limited. There were litter liquid-liquid equilibrium data of PO-water system and some VLE data of ethanol-water system, no VLE dada of PO-water, PO-ethanol and PO-ethanol-water systems can be found in published works.In this paper, the isothermal VLE data of PO-ethanol, PO-water and ethanol-water systems had been measured by using an improved Rose equilibria cell, and the thermodynamic consistency of the experimental data was verified by Herington method. Assuming that the vapor phase as an ideal gas, and liquid phase is a solution of non ideal, the excess Helmholtz free energy in the mixing is calculated by activity coefficient model.Compared the VLE data of ethanol-water system from experiment with the data from literature, it shows that the improved Rose equilibria cell is reliability and operation is correct.The VLE data of three binary systems had been applied to the regression Wilson interaction parameters and NRTL interaction parameters. And Wilson equation, NRTL equation had been applied to predict the VLE data of PO-ethanol-water system at different temperature with the Wilson interaction parameters, NRTL interaction parameters, respectively. While UNIFAC equation been applied to predict the VLE data of ethanol-water, PO-water, PO-ethanol and PO-ethanol-water systems with the group interaction parameters from literature.The results of prediction using Wilson interaction parameters, NRTL interaction parameters were good agreements with experimental data of VLE for PO-ethanol-water system.The maximum average absolute deviation (AAD) of NRTL equation and Wilson equation between calculated and measured values was0.96%and5.52%, respectively. The results of prediction using UNIFAC group interaction parameters from literature were not acceptable. The maximum AAD between calculated of UNIFAC equation and measured values is62.21%. For PO systems, perhaps the data of UNIFAC group parameters is not exact, UNIFAC equation can’t estimate PO-ethanol, PO-water and PO-ethanol-water systems well, thus, it’s necessary to further model, introduct new group, modify parameter and extend parameter matrix.