Synthesis of EMIES/p-TsOH type deep eutectic solvent and its oxidative desulfurization performance

The deep eutectic solvent (DESs) of EMIES/p-TsOH was synthesized by stirring a mixture of 1-ethyl-3-methylimidazolium ethyl sulfate (EMIES) and p-toluene sulfonic acid (p-TsOH), the structure of catalysts was characterized by infrared analysis (FT-IR), hydrogen spectrum analysis (¹H-NMR) and thermogravimetric analysis(TG), the desulfurization performance of model oil was investigated using EMIES/p-TsOH as a catalyst and extraction agent and using H₂O₂ as the oxidation, and the effects of the temperature, n(H₂O₂)/n(S) molar ratio, and the amount of DESs on the desulfurization activity were investigated in detail. Under the optimal conditions, the removal rate of dibenzothiophene (DBT), 4, 6-dimethyldibenzothiophene (4, 6-DMDBT) and benzothiophene (BT) can reach up to 96.2%, 92.2% and 88.8%, respectively. After five recycling runs, the removal rate of DBT can still reach 93.6%. The kinetic analysis of the desulfurization system indicates that the apparent activation energy is 66.4 kJ/mol.