Hierarchical zeolites: synthesis, structural control, and catalytic applications

Zeolites possess unique ion exchange property, abundant acid sites, and highly hydrothermal stability, which have been widely used in catalysis, separation, and adsorption etc. However, the application of zeolite is greatly restrained in catalytic reactions involved in the large molecules due to their small micropore size (<2 nm). Zeolites with hierarchically porous structure not only keep the crystalline framework, acidic sites, and highly hydrothermal stability but also improve diffusion of larger molecules. Thus, the catalyst life can be prolonged, which can expand their applications in the catalysis. In this review, the research progresses of hierarchical zeolites in terms of the controllable pore structural and synthetic strategy are summarized. Additionally, the applications of these hierarchical zeolites in catalysis are concluded. Furthermore, the hierarchical zeolites exhibit more excellent catalytic performance than conventional zeolite with sole micropores. Therefore, a perspective for promising application of the hierarchical zeolite in catalysis field is provided.