Exceptional functionalized dual-acidic ionic liquid: High-efficiency catalytic reaction medium for oxidation desulfurization

The development of highly active functionalized ionic liquids (ILs) as both extractants and catalysts for use in achieving deep desulfurization continues to pose challenges. In this study, a highly efficient oxidative desulfurization system was constructed, composed of dual-acidic ionic liquids (DILs) and H2O2-AcOH. The investigation results of four DILs prepared from different metal chlorides ([HSO3C3NEt3]Cl-MnCln, MnCln = AlCl3, ZnCl2, CuCl2, FeCl3) in oxidative desulfurization showed that [HSO3C3NEt3]Cl-AlCl3 had an outstanding catalytic effect and significantly promoted the oxidation of sulfides. With a 0.2 g [HSO3C3NEt3]Cl-AlCl3, the removal rate of dibenzothiophene (DBT) reached 100% in 10 mL model oil under mild conditions at 55 °C for 20 min. The key is its ability to induce the dismutation of superoxide anions (•O2−), which facilitates the generation of singlet oxygen (1O2). The efficient oxidation of DBT is accomplished through a predominantly 1O2-mediated non-radical mechanism. [HSO3C3NEt3]Cl-AlCl3 serves as a favorable medium for contact to be made between 1O2 and sulfides, which indicates an efficient catalytic-adsorption synergy.