New Pd/SiO₂@ZIF-8 Core–Shell Catalyst with Selective, Antipoisoning, and Antileaching Properties for the Hydrogenation of Alkenes

In this work, we fabricated a new type of Pd/SiO 2 @ZIF-8 core–shell catalyst composed of a Pd/SiO 2 microsphere as the core and a ZIF-8 membrane as the shell. The preparation procedure involves first loading Pd nanoparticles onto nonporous SiO 2 microspheres to obtain the Pd/SiO 2 core and then coating a perfect layer of ZIF-8 shell on the core by electrostatic induction to form a Pd/SiO 2 @ZIF-8 core–shell structure. It is crucial that the modification of the Pd/SiO 2 core with polyelectrolyte was employed to improve the charge distribution of the core surface and preferably adsorb Zn 2+ cations in the synthesis solution so as to assist the formation of a continuous ZIF-8 shell. The compactness and thickness of the shell were optimized by increasing the number of cycles of ZIF-8 growth. The hydrogenations of alkenes with different molecular sizes showed that the Pd/SiO 2 @ZIF-8 catalysts can provide excellent product selectivity and antipoisoning and antileaching properties for the hydrogenations of alkenes.