Desulfurization of fuel-oils with [C2mim][NTf2]: A comparative study

A tendency to use polysubstituted pyridinium-based ionic liquids for desulfurization of fuel-oils is being very remarkable during last years. Are these ones the most suitable ionic liquids for this purpose? The possibility of using a much cheaper ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, has been studied in this work. With this aim, LLE data of the {[C2mim][NTf2] + thiophene + toluene}, {[C2mim][NTf2] + thiophene + n-hexane} and {[C2mim][NTf2] + pyridine + n-hexane} ternary systems have been obtained at T = 298.15 K and atmospheric pressure. The NRTL and UNIQUAC models have been used to correlate the obtained data. Solute distribution ratios and selectivities have been calculated and a comparison with data obtained previously for other ionic liquids has been established. It was found that both cation and anion clearly affect to these thermodynamic parameters. According not just to solubility, but also in terms of selectivity and cost, [C2mim][NTf2] can be a competitive desulfurization solvent.

► Fuels desulfurization with ILs must be analyzed not just in terms of S reduction.
► Smaller chain length of imidazolium cation increases desulfurization selectivity.
► The anion type influences the desulfurization ability of ILs.
► [C2mim][NTf2] can be a competitive desulfurization solvent.