Separation of acetone and methanol azeotropic system using ionic liquid as entrainer

• Capability of three ILs to break the acetone–methanol azeotrope was examined.
• Isobaric VLE data of the acetone + methanol + IL systems was detected.
• [EMIM][OAC] was proposed as a new entrainer to separate acetone + methanol system.
• Ternary VLE data was well correlated by NRTL model.
• Hydrogen bond was discussed to disclose the interaction operating between components and ionic liquid.

In this work, three ionic liquids (ILs), namely monoethanolamine chloride ([HMEA][Cl]), monoethanolamine acetate ([HMEA][OAC]) and 1-ethyl-3-methylimidazole acetate ([EMIM][OAC]), were studied as entrainers to separate acetone + methanol azeotropic mixture by extractive distillation. Isobaric vapor liquid equilibrium of ternary systems containing ILs was investigated to examine the effect between the structure of ionic liquids and separation performance on acetone + methanol. The measurements were carried out at 101.3 kPa and the headspace chromatograph was employed to analyze the VLE data. From the experimental results, it is found that the addition of ILs can remarkably increase the separation factor (relative volatility) of acetone to methanol. The azeotropic point is pulled up and the azeotropy is even eliminated eventually. Comparison of the separation effect of ILs is that [EMIM][OAC] outperforms [HMEA][Cl] and [HMEA][OAC]. The experimental VLE data are well correlated using nonrandom two-liquid model (NRTL).