Effect of methylimidazolium-based ionic liquids on vapor–liquid equilibrium behavior of tert-butyl alcohol + water azeotropic mixture at 101.3 kPa

Three ionic liquids (ILs), 1-ethyl-3-methylimidazolium bromine ([EMIM]Br), 1-butyl-3-methylimidazolium bromine ([BMIM]Br), and 1-hexyl-3-methylimidazolium bromine ([HMIM]Br), were used as the solvent for separation of {tert-butyl alcohol (TBA) + water} azeotrope. Vapor–liquid equilibrium (VLE) data for {TBA + water + IL} ternary systems were measured at 101.3 kPa. The results indicate that all the three ILs produce an obvious effect on the VLE behavior of {TBA + water} system and eliminate the azeotropy in the whole concentration range. [EMIM]Br is the best solvent for the separation of {TBA + water} system by extractive distillation among the three ILs. The experimental VLE data for the ternary systems are correlated with the NRTL model equation with good correlations. Explanations are given with activity coefficients of water and TBA, and the experimental VLE-temperature data for {TBA or water + IL} binary systems.

Extractive distillation is a well-known technology to separate {alcohol + water} azeotropic system, and solvent is needed in this progress to promote the effect of the separation. [EMIM]Br, [BMIM]Br and [HMIM]Br are methylimidazolium-based ionic liquids, which produce an obvious effect on the VLE behavior of {TBA + water} system in the whole concentration range and eliminate the azeotropy. [EMIM]Br is the most favorable candidate solvent for the separation of {TBA + water} azeotropic mixture by extractive distillation among the three ILs.Figure optionsDownload as PowerPoint slide