Hexyl dimethylpyridinium ionic liquids for desulfurization of fuels. Effect of the position of the alkyl side chains

In this work, the desulfurization ability of the 1-hexyl-2,4-dimethylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid, [h2,4mmpy][NTf2], has been compared with that of 1-hexyl-3,5-dimethylpyridinium bis(trifluoromethylsulfonyl)imide, [h3,5mmpy][NTf2]. With this aim, liquid–liquid equilibrium data have been obtained for the [h2,4mmpy][NTf2] + thiophene + toluene, [h2,4mmpy][NTf2] + thiophene + hexane and [h2,4mmpy][NTf2] + pyridine + hexane ternary systems at 298.15 K and atmospheric pressure. The obtained data have been adequately correlated using the UNIQUAC and NRTL models. The suitability of both ionic liquids as solvents for extractive desulfurization has been evaluated in terms of solute distribution ratio and selectivity.

► Hexyl dimethylpyridinium ionic liquids are analysed for fuels desulfurization.
► Related ternary liquid–liquid equilibria are determined.
► The UNIQUAC and the NRTL models satisfactorily correlate obtained data.
► [h2,4mmpy][NTf2] is found as adequate desulfurization agent.
► Asymmetry in the position of the radicals increases the efficiency of extraction.