Comparative study of PW11 and PMo11 encapsulated in UiO-67 for extractive and catalytic oxidative desulfurization: unveiling the superior activity and stability of molybdenum-based catalyst

Two composites, PW 11 @UiO-67 and PMo 11 @UiO-67, were synthesized by encapsulating lacunary Keggin-type polyoxometalates (POMs), PW 11 and PMo 11 , into the zirconium-based metal–organic framework UiO-67 for extractive and catalytic oxidative desulfurization (ECODS) of a multicomponent model fuel. The successful and uniform confinement of POMs within the pores of UiO-67 was verified by ICP-MS, XRD, FT-IR, N 2 physisorption, SEM, XPS and TGA. Catalytic performance tests revealed that both composites can effectively catalyze the oxidation of refractory sulfur compounds (BT, DBT, 4-MDBT, and 4,6-DMDBT) in the presence of H 2 O 2 , while also addressing the inherent recycling problem of homogeneous POM catalysts. Notably, PMo 11 @UiO-67 demonstrated superior activity, achieving >99% desulfurization efficiency under optimized conditions (O/S = 6, 70 °C, 60 min). Kinetic studies established that the oxidative removal of all sulfur species followed pseudo-first-order kinetics, with reactivity descending in the order: DBT > BT ≈ 4-MDBT > 4,6-DMDBT, correlating with sulfur electron density and steric hindrance. Furthermore, PMo 11 @UiO-67 exhibited excellent recyclability, retaining over 94.1% of desulfurization efficiency after six consecutive cycles. This study highlights the enhanced catalytic activity of Mo-based POMs within confined pore structures and elucidates its reaction mechanism through experimental analyses, offering a promising strategy for designing efficient and stable composite catalysts for ultra-deep fuel desulfurization.