Advances in the synthesis and catalysis of solid and hollow zeolite-encapsulated metal catalysts

Metals and zeolites are two important types of catalysts and widely used in oxidation–reduction and acid-catalyzed reactions, respectively. In recent years, zeolite-encapsulated metal catalysts have attracted great interest due to their excellent performance in metal–acid synergistic catalysis, selectivity to desired product, anti-leaching, and anti-sintering of metal. This review highlights the synthesis strategies for solid and hollow zeolite-encapsulated metal catalysts, such as ion-exchange, “ship-in-a-bottle,” hydrothermal crystallization, dry gel conversion, and posttreatment method, and their activity, selectivity, and stability in different reactions including hydrogenation, oxidation, reforming, coupling, reforming, hydroxylation, and degradation. The synthesis and advantages of hollow zeolite-encapsulated metal catalysts in various reactions are highlighted.