Fenton-like ionic liquids/H2O2 system: one-pot extraction combined with oxidation desulfurization of fuel

Abstract

The extraction desulfurization (EDS) and extraction combined with oxidation desulfurization (EODS) for the removal of dibenzothiophene (DBT), benzothiophene (BT), and 4,6-dimethyldibenzothiphene (4,6-DMDBT) in a model oil were carried out in Fenton-like ionic liquids, such as [Et₃NHCl]FeCl₃, [Et₃NHCl]CuCl₂, [Et₃NHCl]ZnCl₂, [Et₃NHCl]CoCl₂, [Et₃NHCl]SnCl₂ and [Et₃NHCl]CrCl₃. The deep desulfurization could be achieved in [Et₃NHCl]FeCl₃ for only 5 min at room temperature. The reaction conditions such as temperature, the molar ratio of H₂O₂ and DBT and the amount of ionic liquid (IL) were investigated in the EODS system. By controlling the way of adding H₂O₂ into the desulfurization system, the sulfur content in the model oil could decrease from 500 mg L⁻¹ to less than 10 mg L⁻¹ at the IL/oil volume of 1 : 5. The oxidation reactivity of the different sulfur-containing compounds was found to be in the order of DBT > BT > 4,6-DMDBT. Moreover, the EODS system could be recycled ten times with a slight decrease in activity to model oil. EODS process was applied to prehydrotreated gasoline and the sulfur content could decrease from 150 to 15 mg L⁻¹ after two rounds of reaction.