Abstract
The thermodynamics and kinetics of oxygen radical formation in cages of a nanoporous crystal, 12CaO·7Al2O3, were examined during isothermal annealing in a dry oxygen atmosphere. The formation of oxygen radicals, O2- and O-, involves the outward diffusion of extraframework oxide ions, their oxidation by absorbed oxygen molecules to form O- and O2- at the surface, and subsequent inward diffusion of the oxygen radicals. The instability of the extraframework oxide ions provides the driving force for this process. Evaluating the radical formation enthalpy and entropy enabled us to determine the temperature and oxygen partial pressure dependences of equilibrium oxygen radical concentration. The rate-limiting process for the radical formation is not the surface reaction, but the total ionic diffusion process, in which the smaller diffusivity of O2- likely dominates the process.
| Original language | English |
|---|---|
| Pages (from-to) | 8920-8925 |
| Number of pages | 6 |
| Journal | Journal of Physical Chemistry B |
| Volume | 108 |
| Issue number | 26 |
| DOIs | |
| Publication status | Published - Jul 1 2004 |
| Externally published | Yes |
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All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry
Cite this
Formation of oxygen radicals in 12CaO·7Al2O3 : Instability of extraframework oxide ions and uptake of oxygen gas. / Hayashi, Katsuro; Matsuishi, Satoru; Hirano, Masahiro; Hosono, Hideo.
In: Journal of Physical Chemistry B, Vol. 108, No. 26, 01.07.2004, p. 8920-8925.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Formation of oxygen radicals in 12CaO·7Al2O3
T2 - Instability of extraframework oxide ions and uptake of oxygen gas
AU - Hayashi, Katsuro
AU - Matsuishi, Satoru
AU - Hirano, Masahiro
AU - Hosono, Hideo
PY - 2004/7/1
Y1 - 2004/7/1
N2 - The thermodynamics and kinetics of oxygen radical formation in cages of a nanoporous crystal, 12CaO·7Al2O3, were examined during isothermal annealing in a dry oxygen atmosphere. The formation of oxygen radicals, O2- and O-, involves the outward diffusion of extraframework oxide ions, their oxidation by absorbed oxygen molecules to form O- and O2- at the surface, and subsequent inward diffusion of the oxygen radicals. The instability of the extraframework oxide ions provides the driving force for this process. Evaluating the radical formation enthalpy and entropy enabled us to determine the temperature and oxygen partial pressure dependences of equilibrium oxygen radical concentration. The rate-limiting process for the radical formation is not the surface reaction, but the total ionic diffusion process, in which the smaller diffusivity of O2- likely dominates the process.
AB - The thermodynamics and kinetics of oxygen radical formation in cages of a nanoporous crystal, 12CaO·7Al2O3, were examined during isothermal annealing in a dry oxygen atmosphere. The formation of oxygen radicals, O2- and O-, involves the outward diffusion of extraframework oxide ions, their oxidation by absorbed oxygen molecules to form O- and O2- at the surface, and subsequent inward diffusion of the oxygen radicals. The instability of the extraframework oxide ions provides the driving force for this process. Evaluating the radical formation enthalpy and entropy enabled us to determine the temperature and oxygen partial pressure dependences of equilibrium oxygen radical concentration. The rate-limiting process for the radical formation is not the surface reaction, but the total ionic diffusion process, in which the smaller diffusivity of O2- likely dominates the process.
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U2 - 10.1021/jp037916n
DO - 10.1021/jp037916n
M3 - Article
AN - SCOPUS:3142736592
VL - 108
SP - 8920
EP - 8925
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 26
ER -