Tungstovanadate-Based Ionic Liquid Catalyst [C2(MIM)2]2VW12O40 Used in Deep Desulfurization for Ultraclean Fuel with Simultaneous Recovery of the Sulfone Product

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.