Investigation into the Internal Factors for the Catalytic Oxidation of Cyclohexane by Zr(IV)-Based Metal-Organic Frameworks

Three porous Zr(IV)-based MOFs, UiO-66, MOF-808 and MOF-802, were selected to catalyze cyclohexane oxidation in order to reveal the intrinsic factors of the active site and catalytic performance. It was found that reducing the number of Zr₆O₈ ligand linkages could improve the catalytic efficiency of cyclohexane oxidation. The main reason for this is the different enrichment abilities of MOFs with different linkage numbers for cyclohexane, which was confirmed by the TPD of cyclohexane and also by GCMC simulations. Meanwhile, the catalytic effect of MOF-802 was lower than expected due to its low porosity and narrow inner pore size. The by-products were identified in detail by GC-MS, providing evidence for this catalytic mechanism. In addition, the potential of this catalyst for industrial applications in cyclohexane oxidation was demonstrated by optimizing the catalytic conditions.