Exposing active sites in zeolites with fluoropyridines as NMR probe molecules

Abstract

Active sites in zeolites are crucial for catalysis, but their identification remains challenging due to structural complexity. Solid-state NMR, a key tool for studying zeolites, can struggle with directly detecting acidic properties due to the quadrupolar nature of ubiquitous metal dopants. Here, we use fluorinated pyridine as a probe to identify active sites in HY and HZSM-5, two important solid acid catalysts. 19F NMR effectively detects binding environments, while 19F–27Al polarization transfer reveals elusive penta-coordinated AlV Brønsted acid sites and shows that the dominant active sites are distorted framework-associated AlIV and AlV sites with large quadrupolar coupling constants, shedding light on catalytic properties. Low-temperature (100 K) NMR proves essential for capturing these interactions. This work enhances the understanding of zeolite active sites and highlights the broad applicability of fluorinated probe molecules for surface characterization, offering a cost-effective, highly sensitive approach for catalytic studies.

Graphical abstract: Exposing active sites in zeolites with fluoropyridines as NMR probe molecules

Supplementary files

Article information

Article type
Paper
Submitted
26 Mar 2025
Accepted
30 Jun 2025
First published
30 Jun 2025
This article is Open Access
Creative Commons BY-NC license

Anal. Methods, 2025, Advance Article

Exposing active sites in zeolites with fluoropyridines as NMR probe molecules

J. Hurd, Y. Ma, P. Cerreia Vioglio, R. Zou, D. Iuga, S. Yang, X. Fan and D. Lee, Anal. Methods, 2025, Advance Article , DOI: 10.1039/D5AY00507H

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