Defective UiO-66(Ce) supported Ni nanoparticles with optimized microenvironment and electronic state for efficient olefin hydrogenation reaction

Defect engineering improves the catalytic performance of metal-organic frameworks (MOFs) loaded metal nanoparticles (MNPs@MOFs), but there is still a challenge in defining the structure-activity relationships. Herein, the content of linker-missing defects in UiO-66(Ce) was systematically regulated via formic acid as the modulators, and defective UiO-66(Ce) loaded Ni nanoparticles (NPs) were constructed for dicyclopentadiene (DCPD) hydrogenation. The fine regulation of defect engineering and reduction conditions affected the structure properties of UiO-66(Ce) and the electronic metal-support interaction between MOFs and Ni NPs, thereby optimizing the microenvironment and electronic state of Ni NPs. The optimized U(Ce)-40eq with suitable defects, small size and structure stability effectively promoted the production of highly dispersed abundant electron-deficient Ni⁰ active sites, enhancing the adsorption and activation of H₂ and C=C bonds, especially accelerating the rate-determining step. Therefore, U(Ce)-40eq loaded 5 wt% Ni NPs achieved DCPD saturated hydrogenation to tetrahydrodicyclopentadiene (70 °C, 2 MPa, 90 min), superior to most high-loading Ni-based catalysts. This work reveals the synergistic mechanism of MOFs defect engineering and electronic structure of Ni NPs, providing effective guidance for the precise preparation of highly efficient and stable MNPs@MOFs heterogeneous catalysts.