Extractive Desulfurization of Liquid Fuel using Modified Pyrollidinium and Phosphonium Based Ionic Liquid Solvents

In the pursuit of better solvents for use in the extractive desulfurization (EDS) of liquid fuel, the pyrollidinium and phosphonium based ionic liquids (ILs) have been improved by combining them with selected molecular compound modifiers. The modifiers, which are imidazole, poly(ethylene) glycol (PEG 200) and sulfolane were selected to induce previously nonexistent mechanisms in the presence of refractory sulfur compounds. The addition of PEG 200 and sulfolane were observed to have a more positive impact on the performance of the ILs than the addition of imidazole under the same conditions. This provides further support for the idea that interaction may not be the predominant interactions for the ILs that are the highly effective in EDS. Using the sulfolane modified tetrabutylphosphonium methanesulfonate [P₄₄₄₄][MeSO₃], up to 81% dibenzothiophene (DBT) removal was recorded at a temperature of 30 °C and solvent-to-mass ratio of 1:1 and after a 30 min mixing time.