Engineering the Electronic Structure of Mo Sites in Mn–Mo–O Mixed-Metal Oxides for Efficient Aerobic Oxidative Desulfurization

Aerobic oxidative desulfurization (AODS) is a vital development aspect for the deep desulfurization of fuel, which requires catalysts with high performance to efficiently convert thiophenic sulfides to sulfones. Here, we demonstrate that Mo sites in Mn–Mo–O mixed-metal oxides (MMOs) can serve as a robust and stable catalyst for the AODS with oxygen contained in atmospheric air as a sustainable oxidant. By systematically studying the effect of the Mn/Mo ratio on the phase, the electronic structure, and the catalytic activity of the MMOs, we reveal that the Mn species could contribute to the partial reduction of Mo species by donating electrons and thereby cause considerable surface defects, further giving our catalyst an improved catalytic performance with a higher turnover frequency value (TOF) compared to the reported MMOs. We show that the optimal catalyst with a Mn/Mo ratio of 4/1 could achieve complete aerobic conversion of dibenzothiophene (DBT) and 4,6-dimethyl-dibenzothiophene (4,6-DMDBT) under mild conditions of 100 °C and atmospheric pressure in 4 h with the TOF value of 4.43 h–1. Finally, the catalyst can be used repeatedly six times without structural change and performance attenuation.