Issue 8, 2023

Regulation of the Si/Al ratios and Al distributions of zeolites and their impact on properties

Abstract

Zeolites are typically a class of crystalline microporous aluminosilicates that are constructed by SiO4 and AlO4 tetrahedra. Because of their unique porous structures, strong Brönsted acidity, molecular-level shape selectivity, exchangeable cations, and high thermal/hydrothermal stability, zeolites are widely used as catalysts, adsorbents, and ion-exchangers in industry. The activity, selectivity, and stability/durability of zeolites in applications are closely related to their Si/Al ratios and Al distributions in the framework. In this review, we discussed the basic principles and the state-of-the-art methodologies for regulating the Si/Al ratios and Al distributions of zeolites, including seed-assisted recipe modification, interzeolite transformation, fluoride media, and usage of organic structure-directing agents (OSDAs), etc. The conventional and newly developed characterization methods for determining the Si/Al ratios and Al distributions were summarized, which include X-ray fluorescence spectroscopy (XRF), solid state 29Si/27Al magic-angle-spinning nuclear magnetic resonance spectroscopy (29Si/27Al MAS NMR), Fourier-transform infrared spectroscopy (FT-IR), etc. The impact of Si/Al ratios and Al distributions on the catalysis, adsorption/separation, and ion-exchange performance of zeolites were subsequently demonstrated. Finally, we presented a perspective on the precise control of the Si/Al ratios and Al distributions of zeolites and the corresponding challenges.

Graphical abstract: Regulation of the Si/Al ratios and Al distributions of zeolites and their impact on properties

Article information

Article type
Review Article
Submitted
31 okt 2022
Accepted
27 dec 2022
First published
28 dec 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 1935-1959

Regulation of the Si/Al ratios and Al distributions of zeolites and their impact on properties

J. Li, M. Gao, W. Yan and J. Yu, Chem. Sci., 2023, 14, 1935 DOI: 10.1039/D2SC06010H

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