Isomer effect in the separation of octane and xylenes using the ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide

The liquid-liquid equilibria of three ternary systems comprising the aliphatic hydrocarbon octane, an aromatic hydrocarbon 1,n-(CH3)(2)C6H4 (where it takes the values 2, 3, or 4; that is, o-xylene, m-xylene, or p-xylene), and the ionic liquid 1-ethyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide [C(2)mim][NTf2]), were experimentally determined at 25 degrees C. The results show a more favourable distribution ratio towards the ionic liquid-rich phase for 1,2-(CH3)(2)C6H4 than for 1,3-(CH3)(2)C6H4 or 1,4-(CH3)(2)C6H4. Although selectivity values prove that it is feasible to separate the aliphatic and aromatic hydrocarbons by using [C(2)mim][NTf2] as solvent, no significant differences are observed in the selectivity among systems. Thus, the proposed ionic liquid does not look suitable to perform the separation of the different xylene isomers in a mixture. The experimental data were satisfactorily correlated by means of the classical 'non-random two-liquid' (NRTL) model. (C) 2010 Elsevier B.V. All rights reserved.