Oxygen exchange between an<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>adsorbate and CaO surfaces

Yanagisawa, Yasunori; Yamabe, Shinichi; Matsumura, Keiko; Huzimura, Ryoitiro

doi:10.1103/physrevb.48.4925

Cited by 5 publications

(9 citation statements)

References 12 publications

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“…No TD's of CO and CO 2 were observed in the temperature range examined, indicating that carbon contamination was absent on the SrO surfaces. Similar exchange features are observed for 18 O 2 -adsorbed CaO powders 8. For SrO and CaO surfaces, the ␥ peaks are the largest.…”

supporting

confidence: 78%

“…In our previous work, ␣ and ␤ peaks below 600 K were analyzed in detail. 8 However, the most significant peak ͑␥͒ of the doubly exchanged oxygen observed at higher temperatures is entirely unresolved, to our knowledge. In this paper, we present the experimental results of the TD analysis of exchanged O 2 on the SrO surface, and an extended MO analysis of the process on MgO, CaO, and SrO surfaces.…”

Section: Introductionmentioning

confidence: 75%

“…8 Due to the energetic equality of key intermediates, this mechanism has been applicable only to the low-temperature peaks where desorption of both singly and doubly exchanged O 2 molecules takes place. We will propose different active sites on the ͑111͒ surfaces for the high-temperature exchange.…”

Section: Cluster Models and Computational Methodsmentioning

confidence: 99%

“…So far we have serially studied oxygen exchange on MgO, 7 CaO, 8 and now SrO through thermal-desorption ͑TD͒ gas analysis and theoretical analysis of the process using a cluster model geometry-optimization with ab initio molecular orbitals ͑MO's͒. In this family of oxides, crystals have wider nearest-neighbor distances in the order of MgO, CaO, and SrO ͑2.10, 2.40, and 2.58 Å, respectively͒.…”

Section: Introductionmentioning

confidence: 99%

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Comparative study of oxygen double exchange betweenO2adsorbate and alkaline-earth oxides

et al. 1996

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Thermal desorption of doubly exchanged oxygen molecules at temperatures above 800 K is observed not from MgO but from CaO and SrO powders after 18 O 2 -gas exposure at room temperature. The exchange reaction was investigated using ab initio molecular-orbital calculations. The defective ͑111͒ surface clusters of CaO and SrO were found to prepare anion-charged reactive centers to accept the O 2 adsorbate. The adsorbate was incorporated into a key O 5 -charged intermediate which can provide an oxygen molecule composed of two lattice atoms for desorption. The nonreactive character of the MgO surface in the ground state is ascribed to the presence of oxygen ions bound strongly at the lattice points. ͓S0163-1829͑96͒04344-5͔

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supporting

confidence: 78%

Section: Introductionmentioning

confidence: 75%

Section: Cluster Models and Computational Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparative study of oxygen double exchange betweenO2adsorbate and alkaline-earth oxides

et al. 1996

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“…Previous results from thermal desorption gas analysis are consistent with this understanding. It was shown that CO, NO, and O 2 desorb at temperatures up to about 1000 K. ,, Thus, the first factor controlling the isotope exchange is the availability of adsorption sites. The physical origin of the 17 kcal/mol apparent activation energy remains unsolved.…”

Section: Discussionmentioning

confidence: 99%

Kinetic Study of Heterogeneous Oxygen-Exchange Reactions and Bulk Self-Diffusion of Oxygen

Acke

Panas

1998

J. Phys. Chem. B

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Apparent activation energies are determined for oxygen-isotope exchange reactions between O2, CO, or NO and preoxidized or prereduced CaO surfaces. Oxygen exchange between N16O or C16O and isotope labeled Ca18O surfaces produced an apparent activation energy of 2 kcal/mol. Similar values are obtained for single- isotope-exchange between 18O18O and prereduced Ca16O surfaces. Apparent activation energies of 15−18 kcal/mol are found for single and double exchange between 18O18O and preoxidized Ca16O surfaces, as well as for double exchange between 18O18O and prereduced Ca16O surfaces. The low apparent activation energies are believed to result from adsorbed intermediates, whereas the high values may involve the formation of a singlet O2 transient. It is shown that eventually the self-diffusion of oxygen ions in the bulk becomes the rate-determining step in the isotope-exchange reaction. Apparent activation energies are determined, and the values are found to depend on surface treatment, (i.e., 44 kcal/mol under reducing and 78 kcal/mol under oxidizing conditions). The involvement of oxygen vacancies under reducing conditions is discussed.

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Interaction of CO with CaO surfaces: A TPD and FTIR study

Yanagisawa

Kashima

2000

Surface Science

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Oxygen exchange between anO2adsorbate and CaO surfaces

Cited by 5 publications

References 12 publications

Comparative study of oxygen double exchange betweenO2adsorbate and alkaline-earth oxides

Comparative study of oxygen double exchange betweenO2adsorbate and alkaline-earth oxides

Kinetic Study of Heterogeneous Oxygen-Exchange Reactions and Bulk Self-Diffusion of Oxygen

Interaction of CO with CaO surfaces: A TPD and FTIR study

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