Counting the acid sites in a commercial ZSM-5 zeolite catalyst

Zachariou, A. et al. (2023) Counting the acid sites in a commercial ZSM-5 zeolite catalyst. ACS Physical Chemistry Au, 3(1), pp. 74-83. (doi: 10.1021/acsphyschemau.2c00040) (PMID:36718264) (PMCID:PMC9881239)

Abstract

This work investigates the acid sites in a commercial ZSM-5 zeolite catalyst by a combination of spectroscopic and physical methods. The Brønsted acid sites in such catalysts are associated with the aluminum substituted into the zeolite lattice, which may not be identical to the total aluminum content of the zeolite. Inelastic neutron scattering spectroscopy (INS) directly quantifies the concentrations of Brønsted acid protons, silanol groups, and hydroxyl groups associated with extra-framework aluminum species. The INS measurements show that ∼50% of the total aluminum content of this particular zeolite is extra framework, a conclusion supported by solid-state NMR and ammonia temperature-programmed desorption (TPD) measurements. Evidence for the presence of extra-framework aluminum oxide species is also seen in neutron powder diffraction data from proton- and deuterium-exchanged samples. The differences between results from the different analytical methods are discussed, and the novelty of direct proton counting by INS in this typical commercial catalyst is emphasized.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Lennon, Professor David and Zachariou, Miss Andrea and Hawkins, Alexander and Parker, Dr Stewart
• Authors: Zachariou, A., Hawkins, A. P., Howe, R. F., Skakle, J. M. S., Barrow, N., Collier, P., Nye, D. W., Smith, R. I., Stenning, G. B. G., Parker, S. F., and Lennon, D.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: ACS Physical Chemistry Au
• Publisher: American Chemical Society
• ISSN: 2694-2445
• ISSN (Online): 2694-2445
• Published Online: 01 November 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in ACS Physical Chemistry Au 3(1): 74-83
• Publisher Policy: Reproduced under a Creative Commons License

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
172233		Anderson ICASE 2015 (Selex)	Heather Lambie	Engineering and Physical Sciences Research Council (EPSRC)	IND CASE EP/N509176/1	S&E - Academic & Student Administration
172921		EPSRC 2016 Industrial Case Award (iCASE) - Jaguar	Miles Padgett	Engineering and Physical Sciences Research Council (EPSRC)	16000061 - EP/P510506/1	Research and Innovation Services