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

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.

Automated summary

Oxidative desulfurization (ODS) using heteropolyacid catalysts has been demonstrated to be an efficient method for removing aromatic sulfur compounds from diesel oils. In this study, a series of novel imidazole-based heteropolyacid catalysts were prepared for deep ODS of fuel, achieving a high desulfurization performance of up to 99.9% under mild conditions. The catalyst also exhibited excellent recovery performance, maintaining a desulfurization activity of 97.7% after seven cycles. Density functional theory calculation revealed that the imidazole-based heteropolyacid catalyst had a lower energy barrier compared to phosphotungstic acid catalyst.