Catalytic kinetics of oxidative desulfurization with surfactant-type polyoxometalate-based ionic liquids

Surfactant-type polyoxometalate-based ionic liquids (SPILs), such as [(n-C8H17)3NCH3]3{PO4[MoO(O2)2]4}, [(n-C12H25)3NCH3]3{PO4[MoO(O2)2]4}, [(n-C8H17)3NCH3]3{PO4[WO(O2)2]4} and [(n-C12H25)3NCH3]3{PO4[WO(O2)2]4} have been investigated on their oxidative desulfurization. SPILs were very promising for the desulfurization of DBT in the model oil using H2O2 as the oxidant. Supposed mechanism and kinetics studies on the catalytic avtivity of SPIL [(n-C8H17)3NCH3]3{PO4[MoO(O2)2]4} revealed that the oxidative desulfurization of organosulfur compounds could present a pseudo first-order kinetic. The reaction rate constant and half-life of DBT oxidation were calculated. Moreover, the catalytic activity for other sulfur-containing compounds increased in the order BT < 4, 6-DMDBT < DBT. There is little change for the oxidative desulfurization efficiency of SPIL after 8 recycles. And this work offers an alternative for oxidative desulfurization of actual prehydrotreated fuel as well.

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► SPILs were designed based on the quaternary ammonium cations pairing with polyoxometalates anions.
► SPIL not only acted as an extractant but also served as a catalyst.
► The mechanism and kinetic of oxidation of DBT were proposed.
► SPILs can deeply remove refractory organosulfur compounds in both model oil and actual fuel.