Isobaric vapor-liquid equilibrium for methanol + methyl acetate with ionic liquids [OMMIM][Tf2N] and [OMIM][Tf2N] as entrainers at 101.3 kPa

The ionic liquids 1-methyl-3-octylimidazoliumbis (trifluoromethylsulfonyl)imide ([OMIM][Tf2N]) and 1,2-dimethyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide ([OMMIM][Tf2N]) were utilized as extractive distillation entrainers to make methanol as the volatile component for the separation of the azeotropic mixture of methanol and methyl acetate. Isobaric VLE data for the methanol (1) + methyl acetate (2) + [OMIM][Tf2N] and methanol (1) + methyl acetate (2) + [OMMIM][Tf2N] were measured at 101.3 kPa. The experimental data were correlated by NRTL model and UNIFAC model, and the NRTL model is more accurate. Both [OMIM][Tf2N] and [OMMIM][Tf2N] produce notable salting-out effects and make methanol as the volatile component, and the azeotropic point of methanol + methyl acetate can be eliminated if the mole fraction of [OMMIM][Tf2N] or [OMIM][Tf2N] is greater than 0.4. The mechanism of [OMMIM][Tf2N] and [OMIM][Tf2N] to improve the relative volatility of methanol to methyl acetate were investigated, and the salting-out effects of [OMMIM][Tf2N] is a little larger.