Separation of azeotrope (ethanol and ethyl methyl carbonate) by different imidazolium-based ionic liquids: Ionic liquids interaction analysis and phase equilibrium measurements

To separate the azeotrope of ethanol and ethyl methyl carbonate (EMC) using ionic liquids (ILs), the σ-profiles of imidazolium-based ILs with different anions [BF4]−, [HSO4]−, [PF6]− and [ClO4]− were calculated by the COSMO-SAC model. Based on the analysis results, 1-ethyl-3-methylimidazolium hydrosulfate ([Emim][HSO4]), 1-propyl-3-methylimidazolium hydrosulfate ([Prmim][HSO4]), 1-butyl-3-methyl-imidazolium hydrosulfate ([Bmim][HSO4]) were selected as extractants to separate ethanol and EMC. The liquid-liquid tie-line data for the ternary systems ethanol + EMC + ILs were measured at 298.15 K under 101.3 kPa, and the influence of ILs with the different alkyl chain length of the cations on the phase behavior was explored. The distribution coefficient and selectivity were calculated to evaluate the extraction capacity of the studied ILs. Meanwhile, the NRTL model was adopted to correlate the experimental results, and the interaction parameters of the NRTL model were also optimized.