Vapor-liquid equilibrium experiment and model prediction for separating ethyl propionate and ethanol using ionic liquids with acetate anion

Abstract Vapor-liquid equilibrium (VLE) data for the binary system of ethyl propionate + ethanol and the ternary systems of ethyl propionate + ethanol +1-decyl-3-methylimidazolium acetate ([DMIM][Ac]), ethyl propionate + ethanol +1-octyl-3-methylimidazolium acetate ([OMIM][Ac]) and ethyl propionate + ethanol +1-hexyl-3-methylimidazolium acetate ([HMIM][Ac]) were measured at 101.3 kPa. The reliability of the experimental procedure and apparatus was checked by comparing the binary experimental data with the literature data. Herington consistency test was conducted to check the thermodynamic consistency of the experimental data for the ethyl propionate + etanol binary system. The UNIQUAC model, NRTL model and Wilson model were used to correlate the vapor-liquid equilibrium data. The results showed that all three models are applicable to the system, but the calculated results by the NRTL model had the minimum deviation from the experimental data. Van Ness consistency test was carried out to check the reliability of the obtained NRTL parameters for thermodynamic consistency for the ternary systems. The addition of the three ionic liquids (ILs) improved the separation of the ethyl propionate-ethanol azeotropic system. Furthermore, the higher the concentration of the ionic liquid, the better the separation effect. The separation performance of the three ILs is: [DMIM][Ac]