Novel liquid–liquid equilibrium data for six ternary systems containing IL, hydrocarbon and thiophene at 25 °C

• Thiophene removal from aliphatic hydrocarbons was investigated using ionic liquids.
• The performance of [Hmim][SCN] and [Omim][SCN] were studied.
• The NRTL model was used for correlation of the experimental data.

Ionic Liquids (IL's) are now considered as useful alternative solvent for the desulfurization of gasoline and diesel oils by liquid–liquid extraction. In this work, 1-hexyl-3-methylimidazolium thiocyanate([Hmim][SCN]) and 1-octyl-3-methylimidazolium thiocyanate([Omim][SCN]) as ionic liquids were investigated as model solvents for removal of thiophene from some aliphatic hydrocarbons (n-hexane, n-octane and n-decane) as fuel model. Liquid–liquid phase equilibrium data were measured for ternary systems containing one ionic liquid as solvent, thiophene as sulfur component and one aliphatic hydrocarbon as fuel model at 298.15 K under ambient pressure. It was found that the IL with lower molecular weight of cation has higher selectivity but lower solute distribution coefficients. Besides, the experimental data demonstrates that the selectivity increases as alkane chain length of fuel model increases while the solubility of ionic liquids decreases, hence the costs of desulfurization process will be decreased. Our results show that for the case of [Hmim][SCN](1) + n-decane(2) + thiophene(3) the highest selectivity and lowest alkane solubility were obtained. In other words [Hmim][SCN] is a more suitable solvent than [Omim][SCN] for desulfurization of higher alkane. Finally in order to find the model parameters, the nonrandom two liquid (NRTL) was used to correlate the experimental data. The results show the model can successfully correlate the experimental data.