Efficient Extractive Desulfurization of Fuel Oils Using N‐Pyrrolidone/Alkylphosphate‐Based Ionic Liquids

Four BrØsted acid ionic liquids (ILS) MMP]DMP], MEP]DEP], HMP]DMP] and HEP]DEP] were synthesized and used as extractants for desulfurization of aromatic sulfur compounds in model oil. The mutual solubility of four ILs were investigated. The extraction equilibrium of four ILs could be reached in as soon as 5 min and the extraction capability followed the order MMP]DMP]>MEP]DEP]>HEP]DEP]>HMP]DMP]. The S extraction showed the highest efficiency under the conditions of 30°C, 30 min and 1:1 (V/V) IL:oil. Under the optimal condition, 70.9% of thiophene (TS), 76.9% of benzothiophene (BT) and 87.5% of dibenzothiophene (DBT) in n‐octane could be efficiently removed by MMP]DMP]. The multiple extraction and regeneration performance of MMP]DMP] for TS was also investigated and the results were satisfying. These results suggest that MMP]DMP] has the best extraction capability and can serve as a promising solvent for extractive desulfurization of fuel oils.