In this work, a series of modified metal-organic frameworks (MOFs) have been prepared by pre-and post-treatment with transition metal oxodiperoxo complexes (MoO(O 2 ) 2 , WO(O 2 ) 2 , and KVO(O 2 ) 2 ). The obtained materials are characterized by XRD, FTIR, SEM, TEM, inductively coupled plasma atomic emission spectrometry (ICP-AES), and X-ray photoelectron spectroscopy (XPS), as well as by N 2 adsorption/desorption measurement. The characterization results show that transition metal oxodiperoxo complexes are uniformly incorporated into the MOF materials without changing the basic structures. The performance of cyclohexane oxidation on metal oxodiperoxo complex modified MOFs are evaluated. UiO-67-KVO(O 2 ) 2 shows the best performance for cyclohexane oxidation, with 78% selectivity to KA oil (KA oil refers to a cyclohexanol and cyclohexanone mixture) at 9.4% conversion. The KA selectivity is found to depend on reaction time, while hot-filtration experiments indicates that the catalytic process is heterogeneous with no leaching of metal species.Materials 2020, 13, 829 2 of 14 metals (Ti, V, Cr, Co, Mn, Fe, Mo) in their oxide forms [14][15][16] are used as catalyst in cyclohexane oxidation reactions, and silica-based material is a common choice as the catalyst support [17][18][19][20][21]. For instance, a mesoporous siliceous material, TUD-1, has been functionalized by different metals, and the obtained M-TUD-1 (M = Co, Cr, Cu, Mn, Mo, Ti, and V) was examined in the liquid phase oxidation of cyclohexane with tert-butyl hydroperoxide (TBHP) as the oxidant. Co-TUD-1 has shown good catalytic activity in cyclohexane conversion, but the radical product, cyclohexyl hydroperoxide (CHHP), is produced in large amounts [22,23]. In a recent study, by introducing a second metal (Mn, Ti, V, or Bi) into Co-TUD-1, the bimetallic TUD-1 showed higher activity and less selectivity towards CHHP in the oxidation of cyclohexane [21]. During the study, metal leaching was one of the main problems in the liquid phase oxidation of cyclohexane because the impregnation, ion-exchange, or isomorphous substitution cannot form strong bonding between the metal species and the support [24][25][26].Metal-organic frameworks (MOFs) have received extensive attention in the field of heterogeneous catalysis due to their high porosity, abundant pore structure, large specific surface area, and easy modification [27][28][29]. MOFs are crystalline materials constructed by linking multidentate ligands with metal/cluster nodes to form infinite networks. The strong coordination interactions between metal and ligand and the infinite three-dimensional structures ensure the good chemical stability of the MOFs and allow for rational design and synthesis [30]. 2,2 -Bipyridine (bpy) is one of the most widely used bidentate chelators in transition metal coordination chemistry [31]. It is very interesting and useful for combining the excellent hydrocarbon oxidation properties of transition metals with the superior properties of MOFs. In our previous work, a molybdenum ...
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