Toward Application of Ionic Liquids to Desulfurization of Fuels: A Review

Over the past decades, the desulfurization of fueloils has been known as one of the most challenging processes inpetroleum refineries due to economic considerations. The presenceof sulfur compounds results in SOxemissions, detrimentallyaffecting the equipment of refineries, the environment, and humanhealth. In this direction, the unique features of ionic liquids haveintroduced them as a beneficial alternative for conventionaldesulfurization of fuel oils using traditional organic solvents. Inthis review, we aim to study ionic liquids used in differentdesulfurization processes of fuel oils, including hydrodesulfuriza-tion (HDS), oxidative desulfurization (ODS), extractive desulfur-ization (EDS), extraction combined with oxidation desulfurization(EODS), extractive and catalytic oxidative desulfurization(ECODS), and liquid-liquid extraction (LLE). Furthermore, governing factors, including temperature, mixing time, reusabilityof ionic liquids, stirring speed, sulfur structure nature, and molar and mass ratios of oxidants, ionic liquids, and catalysts, have beenreviewed in detail.