A new tungstovanadate K4[VW12O40]·21H2O has been prepared by a simple method first and then isolated as [C2(MIM)2]2VW12O40 (VW12-IL) by cation exchange (MIM = 1-methylimidazolium). The designed VW12-IL is employed as a catalyst in an extraction coupled oxidation desulfurization system, which could reach both 100% sulfur removal efficiency and sulfone product selectivity in 20 min with a high turnover frequency value (TOF: 53.2 h–1). Clean fuel and sulfone products are achieved simultaneously after the reaction, accompanied by the crystallization of the sulfone product at the interface of the two phases. In addition, the structure–activity relationship of a series of Keggin polyoxometalate-based ionic liquids (VW12-IL, PV3W9-IL, PVW11-IL, and PW12-IL) and the desulfurization mechanism were proposed by density functional theory and radical quenching, respectively. This work offers a novel perspective to design the structure of the polyoxometalate catalyst and the technological process of oxidative desulfurization.

Achieving long-term stable deep desulfurization at room temperature and recovering high value-added sulfone products is a challenge at present. Herein, a series of catalysts [C n mim] 5 VW 12 O 40 Br (C n VW 12 , 1-alkyl-3-methylimidazolium bromide tungstovanadate, n = 4, 8, 16) were presented for the room temperature catalytic oxidation of dibenzothiophene (DBT) and its derivatives. Factors affecting the reaction process, such as the amount of catalyst, oxidant, and temperature, were systematically discussed. C 16 VW 12 showed higher catalytic performance, and 100% conversion and selectivity could be achieved in 50 min with only 10 mg. The mechanism study showed that the hydroxyl radical was the active radical in the reaction. Benefiting from the "polarity strategy", the sulfone product accumulated after 23 cycles in a C 16 VW 12 system, and the yield and purity were about 84% and 100%, respectively.