Trifluoromethanesulfonic acid-based DESs as extractants and catalysts for removal of DBT from model oil

Abstract

A series of deep eutectic solvents (DESs) of ChCl/XCF₃SO₃H (X from 1.0 to 2.0) were synthesized by stirring a mixture of choline chloride (ChCl) and trifluoromethanesulfonic acid (CF₃SO₃H) at room temperature. The DESs were characterized by Fourier transform infrared (FT-IR) and ¹H nuclear magnetic resonance (¹H NMR). The oxidative desulfurization of model oil was investigated using ChCl/1.5CF₃SO₃H as a catalyst and extraction agent, and H₂O₂ as the oxidant. Some reaction parameters such as type of DES, molar ratio of CF₃SO₃H and ChCl in DESs, H₂O₂ dose, reaction temperature, DES dose and type of sulfur compound were investigated. Under the optimum conditions, the removal rate of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) can reach up to 98.65% and 96.8%, respectively. After five recycling runs, the removal rate of DBT can still reach 97.16%.