Prediction and measurement of phase equilibria for the extraction of BTX from naphtha reformate using BMIMPF6 ionic liquid

New Liquid–Liquid Equilibrium (LLE) data for three ternary systems namely; hexane + benzene + BMIMPF6, heptane + toluene + BMIMPF6, octane + o-xylene + BMIMPF6, and a fourth system consisting of synthetic naphtha reformate which is composed of hexane/heptane/octane + benzene/toluene/o-xylene + BMIMPF6 were obtained. The LLE were determined at T = 298.15 K and atmospheric pressure. Effect of the number of substituted methyls attached to aromatic rings was evaluated in terms of selectivity and extractive capacity of the ionic liquid BMIMPF6. The results showed a decrease of the extracted amount of aromatics by the ionic liquid as the increase of the number attached methyl groups in the corresponding aromatic systems. Thus, the extraction capability of aromatics by BMIMPF6 was in the order of benzene > toluene > o-xylene, either present in individual ternary systems or as mixture in one pseudo ternary system. Five thermodynamics models were used to correlate satisfactorily the LLE data for the four studied ternary systems. These are T-K-Wilson, Dortmund UNIFAC, ASOG, NRTL, and UINQUAC. Different strategies and modifications are made to the group contribution models UNIFAC and ASOG. These modifications showed an improved prediction compared to their original expressions. However, among all models considered in this study, the UINQUAC model gave the best predictions.