Study on the Isobaric Vapor-Liquid Equilibrium Behavior of the Methanol plus Methyl Ethyl Ketone System Using Ionic Liquids as Extractants and Model Correlation

In this work, two ionic liquids (ILs), 1-ethyl-3-methylimidazolium bromide ([EMIM] [Br]) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM]-[DEP]), were used to separate the mixture of methanol and methyl ethyl ketone. Isobaric vapor-liquid equilibrium data for the binary system of methanol + methyl ethyl ketone and the ternary systems of methanol + methyl ethyl ketone + [EMIM] [Br] and methanol + methyl ethyl ketone + [EMIM] [DEP] were measured at 101.3 kPa. The results showed that the two ILs could enhance the relative volatility of methyl ethyl ketone to methanol. The more the content of ILs, the greater the relative volatility of methyl ethyl ketone to methanol. The azeotropic phenomenon of the methanol + methyl ethyl ketone system could be eliminated as the content of ILs reached a specific value. The order of separation ability of the two ILs is [EMIM] [DEP] > [EMIM] [Br]. Finally, the activity coefficient models including the NRTL model and the UNIFAC-Lei model were used to correlate the experimental vapor-liquid equilibrium data, and the correlated results showed that the NRTL model was more suitable to correlate the experimental data.