Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst

Andrea Zachariou, Alexander P Hawkins, Russell F Howe, Janet M S Skakle, Nathan Barrow, Paul Collier, Daniel W Nye, Ronald I Smith, Gavin B G Stenning, Stewart F Parker, David Lennon

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
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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.

Original languageEnglish
Pages (from-to)74-83
Number of pages10
JournalACS physical chemistry Au
Issue number1
Early online date1 Nov 2022
Publication statusPublished - 25 Jan 2023

Bibliographical note

This work was funded by Johnson Matthey plc. through the provision of industrial CASE studentships in partnership with the EPSRC (AZ (EP/N509176/1), APH (EP/P510506/1)). Experiments at the ISIS Neutron and Muon Source were made
possible by beam time allocations from the Science and Technologies Facilities Council.45,46 Resources and support were provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants
EP/R026815/1 and EP/R026939/1


  • HZSM-5
  • inelastic neutron scattering (INS)
  • NMR
  • SEM
  • ammonia chemisorption


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