Vapor-Liquid Equilibria for (n-Hexane, n-Octane, Cyclohexane, or 2,3-Dimethylpentane) plus Toluene + {[4empy][Tf2N] (0.3) + [emim][DCA] (0.7)} Mixed Ionic Liquids

Recently, the study about the use of ionic liquids (ILs) in the aromatic extraction is focused in the selective separation of the hydrocarbons and the solvent in order to propose a whole alternative process involving ILs. As a consequence, the vapor liquid equilibria (VLE) for the hydrocarbons + ILs systems are required. In this work the VLE for several alkane + toluene systems in the presence of the 1-ethyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide ([4empy][Tf2N]) (0.3) + 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) (0.7) binary IL mixture were determined. In addition to extend the experimental VLE information, this work is aimed at the alkane structure evaluation: linear alkanes (n-hexane and n-octane), cyclic alkanes (cyclohexane), and branched-chain alkanes (2,3-dimethylpentane) have been used. All systems have been studied at 323.2, 343.2, and 363.2 K over the whole range of composition within the miscibility region. The NRTL thermodynamic model was used to adjust the VLE for all systems. The high values of alkane/toluene relative volatilities found suggest the alkane selective separation from the reference aromatic hydrocarbon, toluene.