Fluid Phase Equilibria 363 (2014) 248–262 Contents lists available at ScienceDirect Fluid Phase Equilibria j our na l ho me pa ge: www.elsevier.com/locate/fluid Prediction and measurement of phase equilibria for the extraction of BTX from naphtha reformate using BMIMPF 6 ionic liquid Osama A. Al-Rashed a,∗ , Mohamed A. Fahim a,b , Mohamed Shaaban b a Department of Chemical Engineering, College of Engineering and Petroleum, Kuwait University, P. O. Box 5969, Safat 13060, Kuwait b Petroleum Refining & Petrochemicals Research Center, College of Engineering and Petroleum, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait a r t i c l e i n f o Article history: Received 11 January 2013 Received in revised form 24 November 2013 Accepted 25 November 2013 Available online 11 December 2013 Keywords: Aromatic/aliphatic separation Naphtha reformate Liquid–Liquid Equilibria Ionic liquid BMIMPF6 a b s t r a c t New Liquid–Liquid Equilibrium (LLE) data for three ternary systems namely; hex- ane + benzene + BMIMPF 6 , heptane + toluene + BMIMPF 6 , octane + o-xylene + BMIMPF 6 , and a fourth system consisting of synthetic naphtha reformate which is composed of hex- ane/heptane/octane + benzene/toluene/o-xylene + BMIMPF 6 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 BMIMPF 6 . 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 BMIMPF 6 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. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Aromatics are a major sector within the petrochemical indus- try. The key products are Benzene, Toluene, and Xylene which are known as BTX. These aromatics are the raw material of the most important petrochemical intermediates which are used in the production of polymers, solvents, resins, paints, pol- ishes, polyesters, plastics, rubber, fiber, pharmaceutical and food processing agents. Currently petroleum refining is the main source for BTX production. Reformate from catalytic reforming of naph- tha is rich in aromatics as well as aliphatic hydrocarbons. The separation of aromatics BTX from aliphatic hydrocarbon mix- tures is challenging since these hydrocarbons have boiling points in a close range and several combinations form azeotropes [1]. The conventional processes for the separation of these aromatic and aliphatic hydrocarbons mixtures are liquid–liquid extrac- tion, extractive distillation and azeotropic distillation, however; liquid–liquid extraction is more applicable than the other two [2]. Many organic solvents such as sulfolane, dimethylsulfoxide, N- methylpyrrolidone, N-formylmorpholine, methyl carbonate were ∗ Corresponding author. Tel.: +965 24985856; fax: +965 24839498. E-mail address: osama.alrashed@ku.edu.kw (O.A. Al-Rashed). used to extract aromatics from multicomponent hydrocarbon mix- ture [3]. The liquid–liquid extraction by sulfolane showed high recovery of aromatic compounds along with a good balance of solvent properties. These solvents are highly effective and offer high yields, however, the disadvantage of these solvents is due to their toxic and pollutant effects. Additionally, at lower aromatics content (<20 wt.%), the extraction process by sulfolane is less effi- cient as it requires further stages to purify the extract and raffinate phases [4]. Therefore, the improvement of aromatic separation by liquid–liquid extraction has meant the necessity to search for alter- native solvents, which allow an effective separation and cause less damage to the environment instead of the existing ones. Ionic liquids (ILs) have emerged as novel alternatives to tra- ditional solvents because of their nonvolatile nature, low melting point, wide liquid range (over 300 ◦ C), extremely low vapor pres- sure, good thermal stability, non-flammable, high density (usually >1.0 g/mL); and more importantly, they are considered as green solvents, and hence, environmentally safe [5,6]. Furthermore, extraction by ILs is favorable because of the low operating tem- perature (room temperature), rapid phase separation, and an easy IL regeneration for reuse compared to the conventional organic sol- vents. Consequently, researchers around the world directed their attention to ILs based solvents which resulted in a considerable number of publications reporting Liquid–Liquid equilibrium (LLE) 0378-3812/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fluid.2013.11.034