Transformation of St？ber Silica Spheres to Hollow Hierarchical Single-Crystal ZSM-5 Zeolites with Encapsulated Metal Nanocatalysts for Selective Catalysis

The activity of zeolite-supported nanocatalysts is dependent on both the dispersion, size, and location of metal nanoparticles around the zeolite and the size and pore structure of the zeolite. In this study, a synthetic approach was developed to encapsulate metal catalysts within hollow interiors of single-crystal ZSM-5. Briefly, St？ber silica spheres were synthesized and then transformed to single-crystal nano-ZSM-5 (Si/Al = 60), followed by growth of embedded metal nanoparticles and subsequently creation of a nanosized (30–50 nm shell thickness) hollow hierarchical zeolite structure. Metal nanoparticles such as Co, Cu, Cu–Zn, Fe, and Ni can be supported on the inner wall of the hollow zeolite and the surrounding satellite mesopores, without any particles present on the external zeolite surface. When evaluated as a catalyst for the Fischer–Tr？psch reaction, the [email protected] catalyst shows high activity, sintering and coking resistance (50% longer stability than [email protected]), and secondary cracking reactions in the acid sites in the ZSM-5 shell, which reduce C5+ hydrocarbon selectivity and increase smaller-chain hydrocarbon selectivity. In addition, when Pt was further deposited inside the hollow structure, shape-selective alkene hydrogenation was demonstrated. These configured nanoscale zeolite catalysts have potential applications for reactions that involve supported metal nanoparticle catalysis, shape selectivity, or secondary cracking reactions