Hierarchical zeolite Y as hosts for encapsulation of Fe-Schiff base complexes

Abstract

A series of hierarchical zeolite Y samples with different hierarchical qualities, were used as hosts for encapsulation of metal complexes, and their host effects were investigated by XRD, N2 adsorption/desorption, TGA, DR UV-vis, ICP, elemental analysis as well as catalytic reaction. Hierarchical zeolite Y, due to the presence of mesopores, greatly facilitated the transport of Salcn (H2salicyhexen) ligand in zeolite Y crystals, thus the Fe ions exchanged in the cavities of zeolite Y could fully coordinate with ligands, resulting in the prepared hybrids with less un-complexed Fe ions. FeSalcn complexes encapsulated in the hierarchical zeolite Y showed higher catalytic activities than those in the conventional microporous zeolite Y in various cycloalkane oxidation reactions. This can be ascribed to the reduced diffusion constraint imposed by the micropore of zeolite Y and the increased accessibility of encapsulated FeSalcn active sites. Furthermore, the metal complexes encapsulated in the hierarchical zeolite Y exhibited well reusability as those in the conventional zeolite Y. This work gives insights into the host effects of hierarchical zeolite Y on the preparation and catalytic performance of zeolite-encapsulated complexes.