Ionic liquids, EMIMCl and BMIMSCN for sulfur removal from shale oils

Oil shales from Attarat and Sultani were pyrolyzed at 550 °C to produce shale oils for the present study. The organic sulfur content of the two shale oils was determined to be 9.3 and 10.5 wt.%, respectively. Two ionic liquids (IL), 1-ethyl-3-methylimidazolium chloride (EMIMCl) and 1-butyl-3-methylimidazolium thiocyanate (BMIMSCN), were used in liquid–liquid extraction for desulfurization. The extraction process was carried out at room temperature. The liquid–liquid extraction resulted in two-phase formation and redistribution of sulfur compounds into the aqueous IL-rich phase and the shale oil phase. The hydrocarbon sulfur weight percent was determined using a CHNSO analyzer. The removal efficiency for Sultani and Attarat shale oils with EMIMCl was calculated to be 52.4 and 58.1 wt.%, respectively. When BMIMSCN was employed for the extraction of sulfur compounds from Sultani and Attarat shale oils, removal efficiencies of 43.8 and 52.4 wt.% were achieved, respectively. When the surfactant T-80 was added to Sultani shale oil and heated to 60 °C, followed by addition of EMIMCl, the extraction efficiency decreased to 40.9 wt.%. On the other hand, when the mixture of shale oil and IL was heated to 60 °C before adding T-80, the weight percent removal increased to 58.1%.