Separation abilities of three acetate-based ionic liquids for benzene-methanol mixture through vapor-liquid equilibrium experiment at 101.3 kPa

Abstract

Three ionic liquids (ILs) with acetate anion (1-hexyl-3-methylimidazolium acetate, [HMIM][OAC]; 1-octyl-3-methylimidazolium acetate, [OMIM][OAC]; and 1-decyl-3-methylimidazolium acetate, [DMIM][OAC]) were studied as entrainers for separating the benzene-methanol binary azeotrope. Isobaric vapor-liquid equilibrium (VLE) data for the ternary systems of benzene + methanol + IL were measured at 101.3 kPa. The VLE data were well correlated by using the nonrandom two-liquid (NRTL) model. The relative volatility of benzene to methanol is enhanced with the increase in IL content. The azeotropic phenomenon of benzene-methanol mixture can be completely eliminated when IL content reaches a specific value. After the azeotropy of benzene-methanol mixture is completely eliminated, the separation ability of the three ILs follows the order [HMIM][OAC] > [OMIM][OAC] > [DMIM][OAC]. The separation abilities of the three ILs were further analyzed with the help of their σ-profiles.