Effect of framework Al content on HY acidity and cracking activity

M. A. Kuehne, S. M. Babitz, H. H. Kung*, J. T. Miller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


The acidic properties and 2-methylpentane cracking turnover frequencies (TOFs) were compared for HY and two dealuminated HY zeolites with similar levels of framework Al: HDY that was dealuminated by ammonium hexafluorosilicate, and a (H,NH4)-USY zeolite that was dealuminated by steam. The acid strength distributions were determined by microcalorimetry of NH3 adsorption, and the types of acid sites by FTIR spectroscopy. All zeolites possessed Brønsted acid sites with very few Lewis acid sites. The differential heat of adsorption of NH3 on these zeolites was nearly constant: about 120 kJ/mol for HY and HDY and approximately 7 kJ/mol higher for the (H,NH4)-USY. The cracking TOF for HDY was five times larger than HY, while the TOF of (H,NH4)-USY was 80 times higher. These results suggest that the cracking activity may be affected by other factors in addition to acid strength.

Original languageEnglish (US)
Pages (from-to)293-299
Number of pages7
JournalApplied Catalysis A: General
Issue number2
StatePublished - Jan 8 1998


  • Cracking, effect of acidity and AI content
  • USY zeolite, acidity
  • USY zeolite, effect of AI content
  • USY zeolite, hydrocarbon cracking

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology


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