Isobaric Vapor–Liquid Equilibrium Experiments of Methyl Propionate + Ethanol with Different Ionic Liquids at 101.3 kPa

This study investigates the vapor–liquid phase equilibria for the binary system of methyl propionate and ethanol as well as for the ternary system with three ionic liquids, [BMIM][OAC], [EMIM][OAC], and [MMIM][DMP], as extractants. The nonrandom two-liquid (NRTL) model was employed to correlate the vapor–liquid phase equilibrium data. Results indicate that each ionic liquid increases the relative volatility of methyl propionate to ethanol and effectively breaks the azeotrope at a molar fraction of 0.08. The NRTL model exhibited an average relative deviation of 2.46% for binary systems and 3.73, 4.05, and 3.60% for ternary systems. Of the ionic liquids tested, [BMIM][OAC] achieved the highest separation efficiency in the methyl propionate-ethanol azeotropic system.