Analysis of bonding nature being operative in the M(Li, Na, K) ion-exchanged zeolites-CO adsorption systems

Ryotaro Kumashiro, Yasushige Kuroda, Hisayoshi Kobayashi, Mahiko Nagao

Research output: Contribution to journalArticle

Abstract

The nature of the interaction of alkali-metal ion-exchanged ZSM-5 zeolite (MZSM-5; M= Li+, Na+, and K+) with carbon monoxide (CO) molecules was investigated by the adsorption calorimetry and IR spectroscopy, in comparison with the results obtained by the density functional (DF) calculation. For the MZSM-5 - CO systems, a major IR band due to the stretching vibration of CO molecules adsorbed could be resolved into two components. Corresponding to them, two types of adsorbed species with different heats of adsorption were suggested to exist. A linear relationship between the heat of adsorption and the wavenumber of IR band can be established for the MZSM-5 - CO systems, as for the case of copper ion-exchanged ZSM-5 (CuZSM-5) - CO system, though its slope and position are different from the latter case. Taking into consideration that the σ-bonding is operative in the latter system, it is assumed that in the MZSM-5 - CO systems the interaction is of predominantly electrostatic. On the basis of DF theory, the optimized structures for the CO species adsorbed on the two types of alkali-metal ion-exchanged sites were obtained. From these results, it was found that the vibrational frequency and the bonding energy for the CO species adsorbed on the two-coordinated site are higher than those on the three-coordinated site. Such models explained the experimental data satisfactorily.

Original languageEnglish
Pages (from-to)861-864
Number of pages4
JournalStudies in Surface Science and Catalysis
Volume132
Publication statusPublished - 2001

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Zeolites
Carbon Monoxide
Carbon monoxide
zeolites
carbon monoxide
Ions
Adsorption
adsorption
ions
Alkali Metals
Alkali metals
alkali metals
Density functional theory
Metal ions
metal ions
heat
Molecules
Vibrational spectra
Calorimetry
Stretching

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Catalysis

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Analysis of bonding nature being operative in the M(Li, Na, K) ion-exchanged zeolites-CO adsorption systems. / Kumashiro, Ryotaro; Kuroda, Yasushige; Kobayashi, Hisayoshi; Nagao, Mahiko.

In: Studies in Surface Science and Catalysis, Vol. 132, 2001, p. 861-864.

Research output: Contribution to journalArticle

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