One-pot desulfurization of light oils by chemical oxidation and solvent extraction with room temperature ionic liquids

Abstract

We have investigated removing sulfur-containing compounds from light oils by a combination of both chemical oxidation and solvent extraction using the room temperature ionic liquids (RTILs), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM⁺PF₆⁻) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM⁺BF₄⁻). In a one-pot operation, the sulfur-containing compounds in the light oils were extracted into RTILs and then S-oxidized (H₂O₂–acetic acid) to form the corresponding sulfones. The advantage of performing both extraction and oxidation of sulfur compounds from light oil simultaneously in RTILs is that this process increases the desulfurization yield by about an order of magnitude relative to that of merely extracting with RTILs. The room temperature ionic liquids can be recycled after workup and reused without any loss of activity.