Experimental and Theoretical Density Functional Theory Approaches for Desulfurization of Dibenzothiophene from Diesel Fuel with Imidazole-Based Heteropolyacid Catalysts

Abstract

Oxidative desulfurization (ODS) has been proved to be an efficient strategy for the removal of aromatic sulfur compounds from diesel oils, which are one of the main sources of air pollution. Heteropolyacid catalysts are highly active species for ODS, but the promotion of their catalytic activity and clarification of their catalytic mechanism remain an important issue. Herein, a series of novel imidazole-based heteropolyacid catalysts are prepared by a one-pot method for multiphase deep ODS of fuel with hydrogen peroxide as an oxidant. The experimental results show that the desulfurization performance of the prepared imidazole-based heteropolyacid catalysts is high up to 99.9% under mild conditions. The catalyst also possesses excellent recovery performance, and the desulfurization activity remains at 97.7% after being recycled seven times. Furthermore, density functional theory calculation is first employed to clarify the origin of the high desulfurization activity, and the results show that with the imidazole-based heteropolyacid (HPW-VIM) as the catalyst, the energy barrier is much lower than that with phosphotungstic acid (HPW) as the catalyst.

Assessment of Reaction Parameters in the Oxidative Desulfurization Reaction

“…For instance, Ren et al synthesized 1-vinylimidazol-based HPAs with H 5 PMo 10 V 2 O 40 using the one-pot method and applied them to the ODS process of DBT model oil. The results showed that the desulfurization rate of DBT reached 99.9%, and the HPAs were able to maintain for desulfurization rate of 97.7% after being recycled 7 times . Wang et al immobilized H 3 PW 12 O 40 (HPW) onto the surface of a MWW (Mobil composition of matter 22) zeolite for the ODS of petroleum fractions, specifically straight-run gasoline (SRG) and fluid catalytic cracking (FCC) gasoline.…”

“…The results show that S compounds were removed from both the model diesel and real diesel samples using moderate experimental conditions (50 °C and H 2 O 2 /S ratio of 6). 69 Wang et al prepared a series of composite materials consisting of vanadium-substituted Keggin-type polyoxometalates anchored on amine-functionalized Ce-MCM-41 and evaluated for its catalytic activity in ODS of 2000 ppm of DBT model fuel using molecular oxygen as an oxidant. Wang et al found that substitution of V into the Keggin framework of phosphotungstic acid (PTA) has a positive impact on the ODS process, and the conversion of DBT is improved with increasing the V-substituted amount of POM (Table 3).…”