Deep Oxidative Desulfurization of Fuel Catalyzed by Modified Heteropolyacid: The Comparison Performance of Three Kinds of Ionic Liquids

Three kinds of ionic-liquid (IL)-modified heteropolyacids, with one N atom, two N atoms, and cyclic N type of quaternary ammonium salt, were synthesized successfully (S-POM, D-POM, and C-POM), and the relative heterogeneous catalysts system for oxidative desulfurization was obtained from simple one-pot hydrothermal reaction and modified heteropolyacids in the pores of MCM-41 after MOF-199 template self-assembly (S/D/C-POM@MOF@MCM-41). These as-designed samples were characterized via XRD, XPS, TEM, BET analysis, and so on. Results showed that the S/D/C-POM active species could be successfully immobilized into the mesoporous materials and all retained their Keggin structure. C-PMM carried out excellent performance for oxidesulfurization. Under optimal conditions, the rate of DBT removal could reach up to 100% in 90 min, and the catalyst was reused more than 10 times with nearly no significant reduction on catalytic activity. The various sulfur compounds also had an important effect on catalytic performance, which was also investigated and showed the competitive adsorption oxidation with the BT and 4,6-DMDBT in real oils from the DFT calculation. According to the real diesel oxidative desulfurization, it was found that nearly all the sulfur compounds could be completely removed. Meanwhile, a possible mechanism is also studied under the calculation evaluation.