A DRIFT spectroscopic study of the N2 adsorption and acidic properties of H- and Pt/H-zeolites

F. Lónyi, A. Kovács, J. Valyon

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2 Citations (Scopus)

Abstract

The N2 adsorption on zeolite H- and Pt/H-mordenite and Beta (Pt/AlF=0.04-0.08) was studied by DRIFT spectroscopy at room temperature and 1 to 9 bar N2 pressures. The H-bonding of N 2 to the OH groups induced shift of the νOH band to lower frequencies. The ΔνOH shift was taken as a measure of the intrinsic acid strength of the sorption site hydroxyl groups. Results suggested that the intrinsic Brønsted acidity of the H- and the Pt,H-forms were about the same regardless of the amount and oxidation state of the Pt in the sample. In the spectrum of the H2-reduced Pt,H-mordenite, having relatively high Pt content (>1.5 wt%), as a new spectral feature, a νNN absorption band appeared at ∼2232-2245 cm-1. The band was attributed to the νNN vibration of nitrogen, bound to relatively large Pt-clusters. This assignment was supported by the results of the DRIFT examination of the adsorbed CO.

Original languageEnglish
Pages (from-to)869-876
Number of pages8
JournalStudies in Surface Science and Catalysis
Volume158 A
Publication statusPublished - 2005

Fingerprint

Zeolites
Acidity
zeolites
Sorption
Absorption spectra
Spectroscopy
Nitrogen
Adsorption
Oxidation
adsorption
Acids
shift
Carbon Monoxide
acidity
Hydroxyl Radical
sorption
examination
low frequencies
absorption spectra
nitrogen

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Catalysis

Cite this

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title = "A DRIFT spectroscopic study of the N2 adsorption and acidic properties of H- and Pt/H-zeolites",
abstract = "The N2 adsorption on zeolite H- and Pt/H-mordenite and Beta (Pt/AlF=0.04-0.08) was studied by DRIFT spectroscopy at room temperature and 1 to 9 bar N2 pressures. The H-bonding of N 2 to the OH groups induced shift of the νOH band to lower frequencies. The ΔνOH shift was taken as a measure of the intrinsic acid strength of the sorption site hydroxyl groups. Results suggested that the intrinsic Br{\o}nsted acidity of the H- and the Pt,H-forms were about the same regardless of the amount and oxidation state of the Pt in the sample. In the spectrum of the H2-reduced Pt,H-mordenite, having relatively high Pt content (>1.5 wt{\%}), as a new spectral feature, a νNN absorption band appeared at ∼2232-2245 cm-1. The band was attributed to the νNN vibration of nitrogen, bound to relatively large Pt-clusters. This assignment was supported by the results of the DRIFT examination of the adsorbed CO.",
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year = "2005",
language = "English",
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journal = "Studies in Surface Science and Catalysis",
issn = "0167-2991",
publisher = "Elsevier BV",

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TY - JOUR

T1 - A DRIFT spectroscopic study of the N2 adsorption and acidic properties of H- and Pt/H-zeolites

AU - Lónyi, F.

AU - Kovács, A.

AU - Valyon, J.

PY - 2005

Y1 - 2005

N2 - The N2 adsorption on zeolite H- and Pt/H-mordenite and Beta (Pt/AlF=0.04-0.08) was studied by DRIFT spectroscopy at room temperature and 1 to 9 bar N2 pressures. The H-bonding of N 2 to the OH groups induced shift of the νOH band to lower frequencies. The ΔνOH shift was taken as a measure of the intrinsic acid strength of the sorption site hydroxyl groups. Results suggested that the intrinsic Brønsted acidity of the H- and the Pt,H-forms were about the same regardless of the amount and oxidation state of the Pt in the sample. In the spectrum of the H2-reduced Pt,H-mordenite, having relatively high Pt content (>1.5 wt%), as a new spectral feature, a νNN absorption band appeared at ∼2232-2245 cm-1. The band was attributed to the νNN vibration of nitrogen, bound to relatively large Pt-clusters. This assignment was supported by the results of the DRIFT examination of the adsorbed CO.

AB - The N2 adsorption on zeolite H- and Pt/H-mordenite and Beta (Pt/AlF=0.04-0.08) was studied by DRIFT spectroscopy at room temperature and 1 to 9 bar N2 pressures. The H-bonding of N 2 to the OH groups induced shift of the νOH band to lower frequencies. The ΔνOH shift was taken as a measure of the intrinsic acid strength of the sorption site hydroxyl groups. Results suggested that the intrinsic Brønsted acidity of the H- and the Pt,H-forms were about the same regardless of the amount and oxidation state of the Pt in the sample. In the spectrum of the H2-reduced Pt,H-mordenite, having relatively high Pt content (>1.5 wt%), as a new spectral feature, a νNN absorption band appeared at ∼2232-2245 cm-1. The band was attributed to the νNN vibration of nitrogen, bound to relatively large Pt-clusters. This assignment was supported by the results of the DRIFT examination of the adsorbed CO.

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