Isobaric Vapor–Liquid Equilibria for the 2-Propanol + Ethylene Glycol Monopropyl Ether and 2-Butanol + Ethylene Glycol Monopropyl Ether Systems at 60 kPa, 80 kPa, and 100 kPa

Isobaric vapor–liquid equilibria (VLE) for the 2-propanol + ethylene glycol monopropyl ether and 2-butanol + ethylene glycol monopropyl ether binary systems were measured and calculated. The systems were measured using a Fischer VLE 602 apparatus at pressures of 100 kPa, 80 kPa, and 60 kPa and were verified with consistency testing using the Fredenslund and Wisniak methods. The experimental results seem to be thermodynamically consistent considering the Wisniak test results though the Fredenslund test results indicate the possibility of thermodynamic inconsistency. Correlations of the measured data were performed using a two-term virial equation for the fugacity coefficients of the vapor phase and the nonrandom two-liquid (NRTL), universal quasichemical (UNIQUAC), and Wilson activity coefficient models for the activity coefficients of the liquid-phase. The calculation results corresponded well with the experimental data at liquid-phase composition but not at vapor-phase composition, because of difficulty in measuring the vapor-phase and the strong and complicated association of these systems.