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

Fingerprint

Aluminum
Acidity
acidity
Hydroxyl Radical
Zeolites
Adsorption
adsorption
Acids
aluminum
Protons
Sorption
acids
Stabilization
Spectroscopy
zeolites
red shift
sorption
stabilization
protons
spectroscopy

Keywords

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

ASJC Scopus subject areas

  • Catalysis
  • Materials Science(all)

Cite this

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title = "A DRIFT spectroscopic study of the N2 adsorption and acidity of H-faujasites",
abstract = "Br{\o}nsted 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 Br{\o}nsted acid strength regardless of their Al content. In the EFAl-containing USY sample a fraction of the hydroxyl groups showed enhanced Br{\o}nsted acidity.",
keywords = "Acidity, N adsorption, Dealuminated zeolite Y, High-pressure DRIFTS, USY",
author = "F. L{\'o}nyi and J. Valyon and P{\'a}ł, {Borb{\'e}ly G.}",
year = "2003",
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language = "English",
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journal = "Microporous and Mesoporous Materials",
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TY - JOUR

T1 - A DRIFT spectroscopic study of the N2 adsorption and acidity of H-faujasites

AU - Lónyi, F.

AU - Valyon, J.

AU - Páł, Borbély G.

PY - 2003/12/5

Y1 - 2003/12/5

N2 - 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.

AB - 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.

KW - Acidity, N adsorption

KW - Dealuminated zeolite Y

KW - High-pressure DRIFTS

KW - USY

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U2 - 10.1016/j.micromeso.2003.09.018

DO - 10.1016/j.micromeso.2003.09.018

M3 - Article

VL - 66

SP - 273

EP - 282

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

SN - 1387-1811

IS - 2-3

ER -