Encapsulation of H 4 SiW 12 O 40 into an Amide-Functionalized MOF: A Highly Efficient Nanocomposite Catalyst for Oxidative Desulfurization of Diesel Fuel.

Production of hydrocarbon fuels containing sulfur in ultralow levels is in high demand and requires the development of novel catalytic systems for oxidative desulfurization (ODS). Herein, a new nanocomposite SiW@ZSTU-10 catalyst containing HSiWO (SiW) encapsulated into a zinc(II) 3D metal-organic framework (MOF) (ZSTU-10) was assembled and characterized. The intricate structure and porosity of ZSTU-10 permit efficient encapsulation of the catalytically active SiW cages. The impact of different experimental parameters on the ODS of model oil containing dibenzothiophene as a typical S-based contaminant was evaluated. The SiW@ZSTU-10 catalyst exhibits remarkable activity with up to 99.8% sulfur removal in 30 min. Kinetic features, trapping tests, and mechanistic studies were also performed. Furthermore, the catalyst offered an outstanding thermal and chemical stability, without apparent leaching and decline in the activity after six cycles. Such an improved catalytic efficiency of SiW@ZSTU-10 can be assigned to (i) size-matched occupation of the ZSTU-10 pores by SiW-active species, (ii) prevention of polyoxometalate (POM) leaching from the MOF matrix, (iii) facilitation of the access of S-based substrates to the active sites of SiW, and (iv) excellent stability and recyclability of the obtained nanocomposite. The preset work widens a family of promising nanocomposite catalysts for improving the desulfurization performance of hybrid POM-MOF catalytic systems.