Analysis and control of acid sites in zeolites

• Published in: Applied catalysis. A, General Vol. 606; p. 117795
• Main Authors: Palčić, Ana, Valtchev, Valentin
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.09.2020; Elsevier Science SA; Elsevier
• Subjects: Acid sites; Aluminum location; Chemical Sciences; In situ and post-synthesis methods; Zeolites; In situ and post-synthesis methods; Acid sites; Aluminum location; Zeolites; in situ and post-synthesis methods; zeolites; aluminum location; acid sites
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2020.117795

[Display omitted] •Acid sites in aluminosilicate zeolites are revised.•The in situ and post-synthesis methods of aluminum incorporation are highlighted.•The impact of the framework and extra-framework Al species is discussed.•Acid site distribution within a single zeolite crystal is addressed.•Guidelines for zeolite design in terms of acidity are provided. The exceptional catalytic performance of zeolites is due to the presence of active sites in a shape-selective environment, i.e., in micropores with molecular dimensions. The present review provides a comprehensive analysis of active sites in zeolite frameworks. It is focused on the active sites generated by the Al incorporation in the framework. The inclusion of other heteroatoms in the zeolite framework is also addressed. After the introduction of zeolite-type materials and a discussion of the structure-properties relationship in zeolites the central part of the review is devoted to i) the analytical methods and their complementarity for the evaluation of the number, strength, and position of active sites and ii) the in situ and post-synthesis methods of acid sites assessment and control. The data presented herein provide guidelines for making zeolite materials by design in terms of acidity.