Synergistic effect of Zr-MOF on phosphomolybdic acid promotes efficient oxidative desulfurization

Synergistic effects between active metal species and carriers show vital importance to redox catalysts. For this study, a successful synthetic strategy is obtained from hybrid materials involving the combination of phosphomolybdic acid (PMA) and Zr-MOF. The electronic structures of the PMA/UiO-66 composites are elucidated by FTIR, Raman, XPS, UV–vis and NMR spectra. The results suggest that Mo5+ species are newly created on the composites due to the electron transfer from the conduction band of Zr-MOF to PMA. The formed Mo5+ species contribute to a high intrinsic oxidative desulfurization activity for the PMA/UiO-66 composites. Radical scavenger experiments and DFT calculations indicate that Mo5+ with rich electron density facilitates the generation of OH reactive species. The approach can be employed to design other transition metal composite catalysts providing d electrons with unique MOF structures for enhanced catalytic activities of the redox reactions.