Measurements and prediction of ternary liquid-liquid equilibria for mixtures of IL + sulfur compound + hexadecane

For the practical application of ionic liquids as possible solvents for the removal of thiophenic compounds in the diesel fuel, the liquid-liquid equilibrium (LLE) data of such systems is necessary for the design and optimization of process equipment. In this work, LLE experiments were carried out on four ternary systems consisting of one of two pyrrolidinium or phosphonium-based ionic liquids (IL), one of two sulfur compounds and hexadecane as a representative for diesel fuel. For benzothiophene, the system consisting of the [HMPyrr][TFSI] IL as a solvent possesses the highest solute distribution coefficient (2.754) while a solute distribution coefficient of 3.722 was recorded for dibenzothiophene using the [P₄₄₄₄][MeSO₃] as an extraction solvent. The LLE data were fairly correlated with the NRTL model especially at the region of low mole fraction of the sulfur compounds. The data presented in this work can therefore be integrated into process simulators and can be used for preliminary techno-economic evaluation of an ionic liquid-based deep extractive desulfurization of diesel fuel.