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Issue 5, 1994
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Oxygen exchange between magnesium oxide surface and carbon dioxide

Abstract

The isotopic distribution of carbon dioxide desorbed from an MgO surface containing adsorbed 18O-labelled carbon dioxide (C18O2) has been measured by temperature-programmed desorption (TPD), in order to study acid–base pair sites on the surface. Three desorption peaks, differing in both isotopic distribution and temperature of desorption, were observed. The desorption peak in the temperature range 300–400 K (region I) is due to C16O18O and C18O2 in a ratio of nearly 1 : 1. The desorption peak in the range 400–600 K (region II) is composed of C16O2, C16O18O and C18O2, among which C16O2 was most dominant. The third peak appeared in the temperature range 600–1000 K (region III). This peak consists mostly of C16O2. For most of the adsorbed species, the surface Mg2+ contributes to CO2 adsorption. It is concluded that the adsorbed CO2 undergoes multiple oxygen exchange with the surface while migrating over it. Based on IR measurements of the adsorbed CO2, it is suggested that migration takes place during heating of the sample to 473 K in the TPD run.

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Article type: Paper
DOI: 10.1039/FT9949000803
Citation: J. Chem. Soc., Faraday Trans., 1994,90, 803-807
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    Oxygen exchange between magnesium oxide surface and carbon dioxide

    H. Tsuji, T. Shishido, A. Okamura, Y. Gao, H. Hattori and H. Kita, J. Chem. Soc., Faraday Trans., 1994, 90, 803
    DOI: 10.1039/FT9949000803

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