(30g) Zeolite on Demand: Design and Synthesis of Zeolites with Controlled Crystal Morphology and Location of Substituting Tetrahedral Atoms with the Aid of Theoretical Calculations

Authors: 
Chaikittisilp, W., The University of Tokyo
Muraoka, K., The University of Tokyo
Keoh, S. H., The University of Tokyo
Okubo, T., The University of Tokyo
Zeolites, a series of microporous crystalline aluminosilicates and other metallosilicates, have found several applications across a wide range of industries, for example, as catalysts that can selectively crack heavy components in crude oil into smaller, useful chemicals. Synthesis of zeolites has been carried out by a “black-box” sequence of sophisticated hydrothermal reactions; therefore, “trial-and-error” is a routine practice for zeolite synthesis. Over decades, designed and targeted synthesis of useful zeolites with unique pore geometries and morphologies remains an elusive dream in zeolite synthesis, which, if succeed, would drive the communities toward on-demand applications needing more precisely tuned architectures and properties.

Among the 232 known zeolite frameworks, the vast majority of them require an organic structure-directing agent (OSDA) for their synthesis. OSDAs are organic compounds having size and shape that is commensurate with zeolite cavities, thereby providing the framework stabilization and facilitating the formation of zeolites. However, the structure direction of OSDAs at the molecular level has not been fully understood yet. In addition to OSDA, the substituting tetrahedral atoms (e.g., B, Al, and Ga) in the zeolite frameworks affect the formation of zeolites. Moreover, these substitutes are one of the key factors determining the physicochemical properties of zeolites.

Here, our attempts to understand the interactions between OSDAs and zeolite frameworks and the intrinsic influences of the contents and locations of the substituting atoms towards engineering of the physicochemical properties and morphologies of zeolites are presented [1–3].

[1] K. Muraoka, W. Chaikittisilp, T. Okubo, J. Am. Chem. Soc. 2016, 138, 6184−6193.

[2] S. H. Keoh, W. Chaikittisilp, K. Muraoka, R. R. Mukti, A. Shimojima, P. Kumar, M. Tsapatsis, T. Okubo, Chem. Mater. 2016, 28, 8997−9007.

[3] S. H. Keoh, W. Chaikittisilp, A. Endo, A. Shimojima, T. Okubo, Bull. Chem. Soc. Jpn. 2017, 90, 586−594.