Zeolites are well known for their ordered microporous networks, good hydrothermal stability, large surface area, high acidity and selectivity. These excellent properties make zeolites extremely useful for petrochemical processes and refining. However, the presence of only microporous channels also restricts the diffusion of reactants and products into and out of the microporous networks, especially limiting zeolite applications involving bulky molecules. The importance of developing hierarchical zeolites has attracted great attention in recent years due to the prospect of increased accessibility for bulky molecules. Introducing additional mesoporosity, and even macroporosity, into conventional zeolites produces a combination of three different size scales of porosity. It expands the original zeolite hierarchical structure and greatly enhances the mass transport of molecules while maintaining the intrinsic size, shape and transition state selectivity of zeolite. The promising applications of this new zeolite architecture have prompted a multitude of efforts to develop a variety of different synthesis strategies. In this review, we summarized and evaluated the modern synthesis strategies (bottom-up and top-down) for introducing additional meso/macroporosity into microporous zeolites. The advantages and limitations of these different strategies were discussed in detail.
Bibliographical noteFunding Information:
The authors would like to thank the Royal Society of New Zealand for funding this work under the NZ-Korea Joint Research Project (KOR-UOC1101).
Royal Society of New Zealand, 501100001509, The authors would like to thank the Royal Society of New Zealand for funding this work under the NZ-Korea Joint Research Project (KOR-UOC1101)., ?, Open Access for this article was sponsored by the Society of Powder Technology, Japan, through the KAKENHI Grant Number 18HP2009/ Grant-in-Aid for Publication of Scientific Research Results, Japan Society for the Promotion of Science, 2018.
© 2018 The Society of Powder Technology Japan
- Bottom-up and top-down
- Hierarchical zeolite
ASJC Scopus subject areas
- General Chemical Engineering
- Mechanics of Materials