Confinement Effects in Zeolite-Confined Noble Metals.

Confinement of noble nanometals in a zeolite matrix is a promising way to special types of catalysts that show significant advantages in size control, site adjustment, and nano-architecture design. The beauty of zeolite-confined noble metals lies in their unique confinement effects on a molecular scale, and thus enables spatially confined catalysis akin to enzyme catalysis. In this Minireview, the confined synthesis strategies of zeolite-confined noble metals will be briefly discussed, showing the processes, advantages, features, and mechanisms. The confined catalysis carried on zeolite-confined noble metals will be summarized, and great emphasis will be paid to the confinement effects involving size, encapsulation, recognition, and synergy. Great progress of atomic sites in the size effect, supercage stabilization in the encapsulation effect, site adsorption in the recognition effect, and cascade reaction in the synergy effect are highlighted. This Minireview is concluded with challenges and opportunities in terms of the synthesis of zeolite-confined noble metals and their applications to design multifunctional catalysts with high catalytic activity, selectivity, and stability.