Hyperordered Structures in Microporous Frameworks in Zeolites

Zeolites are one of the ordered microporous materials and widely used in industrial fields, such as adsorption and catalysis. Over 250 of zeolite topologies have been approved by the Structure Commission of the International Zeolite Association (IZA-SC). Their 3-dimensional structures in zeolite framework directly affected their adsorption–desorption and catalytic performance, and the concentration and locations of Al atoms also determine the cation-exchange capacity and catalytic activity. In this chapter, we briefly summarize the hyperordered structures, such as polymorphs and Al siting and distribution. Furthermore, enormous efforts have been devoted to elucidating and analyzing the hyperordered structures of zeolites, which is still considered difficult and is under development. Characterization methods, such as X-ray diffraction, electric microscopy, nuclear magnetic resonance, and UV–Vis spectroscopy, to correctly understand the hyperordered structures related to Al atoms of zeolites are also reviewed. Particularly, silanol groups contained in zeolite frameworks can be also considered as hyperordered structures to determine their features such as hydrothermal stability and production selectivity in catalytic reactions. Finally, types of different silanol groups in zeolite frameworks and monitoring method for silanol groups were described.