Impact of Mineralizing Agents on Aluminum Distribution and Acidity of ZSM‐5 Zeolites. Issue 7 (11th January 2023)

• Record Type: Journal Article
• Authors: Al‐Nahari, Shadi; Dib, Eddy; Cammarano, Claudia; Saint‐Germes, Etienne; Massiot, Dominique; Sarou‐Kanian, Vincent; Alonso, Bruno
• Is Part Of: Angewandte Chemie international edition. Volume 62:Issue 7(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-11
• Subjects: Acidity -- Electrostatic Interactions -- NMR Spectroscopy -- Temperature Programmed Desorption -- Zeolites; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202217992
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Intensive research on improving the catalytic properties of zeolites is focused on modulating their acidity and the distribution of associated Al sites. Herein, by studying a series of ZSM‐5 zeolites over a broad range of Al content, we demonstrate how the nature of the mineralizing agent (F − or OH − ) used in hydrothermal syntheses directly impacts Al sites distribution. The proportions of Al sites, probed by 27 Al NMR, depend on the Si/Al ratio for F −, but remain identical for OH − (from Si/Al=30 to 760). This leads to contrasting variations in weak and strong acidities. Such opposite effect of mineralizers is explained by the spatial location of negative charges and the resulting balance between short‐ and long‐range electrostatic interactions. This understanding paves the way for additional and simple opportunities to control zeolites' acidity. Abstract : The mineralizing agents F − and OH − directly influence aluminum distribution in ZSM‐5. The proportion of Al sites depends on the Si/Al ratio for F −, but remains identical for OH − (from Si/Al=30 to 760). This effect offers a simple and new opportunity to control zeolite acidity and further reactivity.