[BMIM]BF4 and [BMIM]PF6 ionic liquids for sulfur extraction from Jordanian shale oils

Two different shale oils were produced by the pyrolysis of oil shale from the Attarat Um-Ghudran and El-Lajjun areas in Jordan. The ionic liquids [BMIM]BF4 and [BMIM]PF6 were used to extract sulfur compounds from the shale oils. The two shale oils generated from Attarat and El-Lajjun were found to contain 12.1 and 11.2 wt.% sulfur, respectively. The extraction of sulfur compounds from shale oil was studied at 20, 40, and 60 °C, with 40 °C being the optimum. The volume ratios of ionic liquid to shale oil (IL/SO) investigated were 1.0:1.0, 1.0:3.0, 1.0:5.0, 1.0:8.0, and 1.0:10.0. For Attarat shale oil, the 1.0:5.0 ratio resulted in removal efficiencies of 58.7% (7.1/12.1) and 54.6% (6.6/12.1) for [BMIM]PF6 and [BMIM]BF4, respectively, which were lower than those calculated for the 1.0:1.0 (IL/SO) ratio, i.e., 62.8% (7.6/12.1) and 57.9% (7.0/12.1), respectively. However, the 1.0:5.0 ratio is more economical and was therefore selected. Based on the calculated extraction efficiencies, [BMIM]PF6 is a slightly more effective extracting agent.