Preparation of N-Methylimidazoliun Fluoroborate-Based Deep Eutectic Solvent and Its Oxidative Desulfurization Performance

[HMIM]BF4/xC9H10O2 (x=0.5, 1, 2) type acidic deep eutectic solvents (DESs) were synthesized using N-methylimidazoliun fluoroborate ([HMIM]BF4) and phenylpropionic acid (C9H10O2) as raw materials, and then these DESs were characterized by FT-IR, 1H NMR and TGA. In addition, with using [HMIM]BF4/0.5C9H10O2 deep eutectic solvent as extractant and catalyst, and H2O2 as oxidant, desulfurization was performed with dibenzothiophene(DBT) as model compound in a simulated oil system. Effects of n(C9H10O2)/n([HMIM]BF4), reaction temperature, n(H2O2)/n(S), the amount of deep eutectic solvent and different sulfur compounds on desulfurization performance were investigated. Experimental results indicate that, under the optimum conditions (i. e., 5 mL oil volume, n(C9H10O2)/n([HMIM]BF4)=0.5, reaction temperature 60℃, reaction time 180 min, n(H2O2)/n(S)=8, V(DESs)=1.0 mL), desulfurization ratios of DBT, 4, 6-dimethyl-dibenzothiophene (4, 6-DMDBT) and benzothiophene (BT) are 98.4%, 93% and 89.6%, correspondingly. Infrared spectroscopy analysis show there are strong interactions between DBT and DESs, which can cause DBT structure to be distorted. After 5 cycles of reaction, desulfurization ratio is still as high as 90.2%, which indicates that [HMIM]BF4/0.5C9H10O2 demonstrates high stability. © 2020, Editorial Office of Acta Petrolei Sinica(Petroleum Processing Section). All right reserved.