Extraction desulfurization process of fuels with ionic liquids

• Extraction of thiophene and benzothiophene from heptane.
• The ternary (liquid + liquid) equilibria using ILs.
• High selectivity and solute distribution ratio for the extraction of sulfur compounds form alkanes.
• [BMPYR][TCM] was proposed as entrainer for the separation process.

In this work, we studied the applicability of three ionic liquids (ILs) in the extraction of thiophene, or benzothiophene from heptane at T = 308.15 K and ambient pressure. Experimental data for (liquid + liquid) phase equilibrium (LLE) were obtained for five ternary systems. The 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, [BMPYR][CF3SO3], 1-butyl-1-methylpyrrolidinium tricyanomethanide, [BMPYR][TCM] and 1-hexyl-3-methylimidazolium tetracyanoborate, [HMIM][TCB] were used for the desulfurization process. The [BMPYR][CF3SO3] showed much better selectivity than [HMIM][TCB] in the extraction of thiophene from heptane and all of them showed excellent results in terms of benzothiophene selectivity and distribution ratio compared to what is currently published for different ILs. Chromatography analysis showed that IL was not present in the heptane layer. This eliminates the process of the separation of the solvent from the raffinate layer. The data obtained have been correlated with the non-random two liquid NRTL model. The experimental tie-lines and the phase composition in mole fraction in the ternary systems were calculated with an average root mean square deviation (RMSD) of 0.005.

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