Green Encapsulation of Palladium on Defective Hierarchical UiO‐66 Under Solvent‐Free Conditions for Efficient Olefin Hydrogenation Catalyst

ABSTRACT Highly dispersed palladium nanoparticles (Pd NPs) embedded within a hierarchical UiO‐66 structure, referred to as Pd@U‐12, have been successfully synthesized via a green, straightforward of solid‐solid thermal (SST) method. This innovative SST technique enables uniform dispersion of Pd NPs, allowing their encapsulation within the hierarchical framework of UiO‐66. The unsaturated sites in the host UiO‐66 facilitate the coordination of Pd, which are subsequently reduced to nanoparticles during the SST process, forming Pd@U‐12. The Pd NPs are highly dispersed on the hierarchical support (U‐12) and serve effectively as catalytic sites for hydrogenation reactions. The optimally synthesized 20%Pd@U‐12 demonstrated exceptional performance as a heterogeneous catalyst for the hydrogenation of cyclohexene, achieving 99% conversion with stable activity over five consecutive cycles. Notably, the SST method for encapsulating Pd NPs (Pd@U‐12) offers several advantages, including rapid incorporation of metal nanoparticles within a short time, a green, solvent‐free synthesis process, high dispersion and stability of the metal content within the host material. These features could significantly enhance the effectiveness of Pd@U‐12 as a robust heterogeneous catalyst in various catalysis applications.