A DRIFT spectroscopic study of the N2 adsorption and acidity of H-faujasites

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Abstract

Brønsted acidity of faujasite (FAU) type zeolites, such as, H-Y, dealuminated H-Y, and ultra-stabilized H-Y (USY) was studied by DRIFT spectroscopy using N2 adsorption at 298 K and at pressures ranging from 1 to 9 bar for probing of the acidic sorption sites. Both the α- and β-cage hydroxyl-groups were found to establish H-bonds with N2. Dealumination by (NH4)2[SiF6] or ultra-stabilization increased the accessibility of the β-cage protons. The ΔνOH red shift, induced by the adsorption, was used as a measure of the intrinsic acid strength of the OH-groups. Samples, free of extra-framework aluminum (EFAl) species, had about the same Brønsted acid strength regardless of their Al content. In the EFAl-containing USY sample a fraction of the hydroxyl groups showed enhanced Brønsted acidity.

Original languageEnglish
Pages (from-to)273-282
Number of pages10
JournalMicroporous and Mesoporous Materials
Volume66
Issue number2-3
DOIs
Publication statusPublished - Dec 5 2003

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Keywords

  • Acidity, N adsorption
  • Dealuminated zeolite Y
  • High-pressure DRIFTS
  • USY

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials

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