Oxidative and extractive desulfurization of petroleum middle distillates, using imidazole ionic liquids

Abstract

The desulfurization of four petroleum distillates i.e. kerosene, light gas oil (LGO), heavy gas oil (HGO) and light cycle oil (LCO), with sulfur content 0.206–1.272% w/w, was carried out using the hydrogen peroxide-acetic acid oxidative system, in combination with extractive desulfurization performed by imidazolium based ionic liquids. The 1-butyl-3-methylimidazolium bromide [BMIM][Br], and 1-butyl-3-methylimidazolium hydrogen sulfate [BMIM][HSO4] were synthesized, characterized with FT-IR and 1H NMR, and used as solvents in a six extraction cycle procedure. The influence of temperature in the extraction process was investigated. In each extraction cycle, the sulfur content and the physical properties of the raffinates were estimated. The used ionic liquids were recovered and regenerated, in a quite efficient regeneration process. The synthesized and recycled ionic liquids show a mild desulfurization capability, depending on the feed under extraction. In every case, [BMIM][Br] prevails over [BMIM][HSO4] in desulfurization efficiency.

Keywords

• Ionic liquids
• Oxidative desulfurization
• Extraction
• Recycling
• IR spectroscopy
• NMR spectroscopy