Characterization by ammonia adsorption microcalorimetry of substantially amorphous or partially crystalline ZSM-5 materials and correlation with catalytic activity

C. P. Nicolaides, H. H. Kung, N. P. Makgoba, N. P. Sincadu, M. S. Scurrell

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Ammonia adsorption microcalorimetry studies have shown that for ZSM-5-based materials, whose XRD crystallinity was varied from 3 to 70%, the number of strong Brønsted acid sites, that is those with a ΔHads between 120 and 140 kJ/mol, increases with increasing XRD crystallinity. A strong correlation was observed between the catalytic activity of these zeolite-based materials in terms of the demanding n-hexane cracking reaction and the number of strong acid sites. For samples with XRD crystallinities below 30%, however, the number of strong acid sites is disproportionately low and the catalytic activity only becomes significant at crystallinities above this level.

Original languageEnglish
Pages (from-to)29-33
Number of pages5
JournalApplied Catalysis A: General
Issue number1-2
Publication statusPublished - Jan 5 2002



  • Aluminosilicate
  • Ammonia adsorption microcalorimetry
  • Brønsted acid
  • Cracking
  • NAS catalysts
  • Zeolite

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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