Isobaric vapor–liquid equilibrium for methanol + dimethyl carbonate + phosphoric-based ionic liquids

• VLE data for methanol + DMC + phosphoric-based ionic liquids measured at 101.3 kPa.
• The azeotropic point is totally eliminated by ILs investigated at xIL > 0.15.
• The ILs have a great salting-out effect, which enhances the relative volatility of DMC.
• The e-NRTL model can correlate the experimental VLE data with a good accuracy.
• The ILs investigated are promising entrainers for the separation of methanol and DMC.

Isobaric vapor–liquid equilibrium (VLE) at 101.3 kPa for methanol + 1-methyl-3-methylimidazolium dimethylphosphate ([MMIM][DMP]), dimethyl carbonate (DMC) + [MMIM][DMP], methanol + 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and DMC + [EMIM][DEP] binary systems, as well as the VLE for the methanol + DMC + [MMIM][DMP] and methanol + DMC + [EMIM][DEP] ternary systems are measured using a circulation VLE still. With the addition of ionic liquids into the azeotropic system of methanol + DMC, the relative volatility of DMC is enhanced, which shows a salting-out effect of ionic liquids. The azeotropic point disappears when the mole fraction of ionic liquids is above 0.15. The salting-out effect on the DMC produced by [MMIM][DMP] is stronger than that produced by [EMIM][DEP]. The equilibrium experimental data is well correlated by the electrolyte nonrandom two-liquid model.

Potential entrainers for the separation of methanol and DMC in extractive distillation.Figure optionsDownload as PowerPoint slide