SEPARATION OF TOLUENE FROM HYDROCARBON MIXTURES USING IONIC LIQUIDS [EMim][NTf2] AND [EMpy][NTf2]

The study is a continuation of our previous work on the separation of aromatic hydrocarbons from their mixtures with alkanes using ionic liquids (ILs). In this paper, two ILs with different cation and the same anion and the same substituents and anion: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMim][NTf2]) and 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide ([EMpy][NTf2]), were used for the separation of toluene from its mixture with alkane (cyclohexane). The impact of the difference between an imidazolium cation and a pyridinium cation on the separation process efficiency was studied. Besides, ILs with the [NTf2] anion were also chosen for their relatively low viscosity and availability. For the thermodynamic description of ternary liquid-liquid equilibrium, the NRTL equation (the Non-Random Two Liquid model) was applied. The effect of the imidazolium and pyridinium cations on the separation of toluene from the mentioned hydrocarbons mixture is documented as the simulation results of counter-current extractors, and the number of theoretical stages, solvent to feed mole ratio, and the product purity were tested. Results of the simulation for a preset criterion were compared to those obtained with sulfolane, an extraction solvent considered as a benchmark for the aromatic-aliphatic hydrocarbon mixtures separation. The results have been processed in form of tables and comparative diagrams.