A Conceptual Review of Core–Shell Zeolite–Zeolite Composites for Catalytic Applications

Although conventional zeolites, a class of crystalline aluminosilicate materials, have been extensively developed over the past decades, they typically contain only a single framework, which often cannot simultaneously meet the several requirements of various catalytic applications, such as optimal activity, selectivity, and resistance to deactivation. To date, the rational design of zeolite–zeolite composites has played a key role in the zeolite and catalysis communities. In this review, we summarize the recent progress on the rational design of zeolite composites with multiple framework types, hierarchical porosity, multifunctional active sites, and tunable acidity. Such features can generate synergistic effects between different zeolite topologies or compositions that are unattainable in individual zeolites. This also includes a conceptual analysis of core–shell zeolite–zeolite composites in different aspects, such as their synthesis strategies, structural characteristics, and synergistic catalytic performances in several catalytic applications, including methanol conversion, isomerization, cracking, hydrogenation, dehydrogenation, and other related catalytic processes. This enables new avenues for advanced zeolite design for a wide range of catalytic applications, which would be beneficial for practical uses in future.