Amino-functionalized seeds-induced synthesis of encapsulated Pd@Silicalite-1 core-shell catalysts for size-selective hydrogenation

Abstract

Silicalite-1 (S-1) encapsulated Pd@Silicalite-1 (Pd@S-1) core-shell catalysts were prepared by using a seeds-induced growth strategy, including immobilization of Pd2+ on amino-functionalized S-1 seeds and regrowth of the S-1 zeolite. The microstructure and elemental composition of Pd@S-1 core-shell catalysts were characterized by FE-SEM, TEM, XRD, XPS and ICP-AES. The results indicate Pd NPs are encapsulated and well dispersed in S-1 crystals and have a narrow size distribution of around 3.2 nm. This core-shell catalyst demonstrates excellent shape selectivity in the hydrogenation of alkenes compared with conventional Pd/S-1 obtained by directly loading Pd NPs on S-1 without regrowth.