Size effect of encapsulated metal within zeolite: Biomass, CO2 and methane utilization

Zeolites can effectively prevent agglomeration and sintering of metal particles through their unique limiting effect during encapsulation and reaction, thus maintaining uniform metal size. Here, recent advances in the size effect of encapsulated metals within zeolite were summarized. First, methods for modulating the particle size of metal encapsulated in zeolites were reviewed, including impregnation, in-situ encapsulating method, inter-zeolite transformation method and metal/zeolite seeds method. Afterwards, the role of encapsulated metal size effect in biomass upgrading, carbon dioxide utilization and methane oxidation was summarized to further understand the indispensable role of encapsulated metal size effect in constrained catalysis. In addition, the fundamentals of the encapsulated metal size effect were discussed in terms of both geometric and electronic effects. Finally, unique insights were provided into the issues and challenges of encapsulated metal size effects. This will help to fully exploit the metal potential in constrained catalysis.