Characterization of active sites on copper ion-exchanged mordenite for dinitrogen adsorption by using CO as a probe molecule

Yasushige Kuroda, Hironobu Maeda, Yuzo Yoshikawa, Ryotaro Kumashiro, Mahiko Nagao

Research output: Contribution to journalArticle

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Abstract

The peculiar feature of copper ion-exchanged mordenite in dinitrogen (N2) adsorption has been investigated through the measurements of infrared (IR) and emission spectra (ES) and X-ray absorption fine structure (XAFS). IR spectra provided the definitive evidence for the existence of at least two kinds of adsorption sites on the 873 K-treated copper ion-exchanged mordenite; the absorption bands centered at 2160 and 2150 cm-1 appeared when CO molecules were adsorbed. The adsorbed species assigned to the former band was desorbed at 573 K in vacuo and that to the latter one at 473 K. It was found that the site responsible for the latter band acts as effective sites for N2 adsorption. XAFS spectra also showed new bands due to the CO adsorption on copper ion at 1.48 Å, 2.52 Å, and 8.981 keV, together with bands at 1.85 Å and 8.993 keV. The former set of bands was concomitant with the appearance of an IR band at 2150 cm-1 due to the adsorbed CO species. The two bands (at 8.981 and 8.993 keV) observed in the XAFS spectra for the CO-adsorbed sample are explained in terms of the formation of a planar three- or four-coordinate site through the reaction of copper ions with CO molecules. CO adsorption also caused a significant shift of the emission band from 470 to 430 nm. This band reverted to the original position by evacuating the sample at 473 K, accompanying a liberation of CO. This makes possible the interpretation that the adsorption site responsible for respective bands at 2150 cm-1 in IR, at 430 nm in ES, and at 8.981 keV in XAFS spectra through the interaction with CO molecules is effective for N2 adsorption at ambient temperature.

Original languageEnglish
Pages (from-to)1312-1316
Number of pages5
JournalJournal of Physical Chemistry B
Volume101
Issue number8
Publication statusPublished - Feb 20 1997

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Carbon Monoxide
Copper
Ions
Adsorption
copper
X ray absorption
Molecules
adsorption
probes
molecules
ions
Infrared radiation
fine structure
emission spectra
x rays
infrared spectra
evacuating
mordenite
Absorption spectra
ambient temperature

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Engineering(all)

Cite this

Characterization of active sites on copper ion-exchanged mordenite for dinitrogen adsorption by using CO as a probe molecule. / Kuroda, Yasushige; Maeda, Hironobu; Yoshikawa, Yuzo; Kumashiro, Ryotaro; Nagao, Mahiko.

In: Journal of Physical Chemistry B, Vol. 101, No. 8, 20.02.1997, p. 1312-1316.

Research output: Contribution to journalArticle

Kuroda, Yasushige ; Maeda, Hironobu ; Yoshikawa, Yuzo ; Kumashiro, Ryotaro ; Nagao, Mahiko. / Characterization of active sites on copper ion-exchanged mordenite for dinitrogen adsorption by using CO as a probe molecule. In: Journal of Physical Chemistry B. 1997 ; Vol. 101, No. 8. pp. 1312-1316.
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