Formation and Desorption of Oxygen Species in Nanoporous Crystal 12CaO·7Al2O3

Shuwu Yang, Junko N. Kondo, Katsuro Hayashi, Masahiro Hirano, Kazunari Domen, Hideo Hosono

研究成果: ジャーナルへの寄稿学術誌査読

70 被引用数 (Scopus)

抄録

The formation and desorption mechanisms of oxygen species in nanoporous crystal 12CaO· 7Al2O3 (C12A 7) are studied by temperature-programmed desorption (TPD), electron-spin resonance (ESR), and Raman spectroscopy. Various oxygen ion species, including O-, O2-, and O 22-, are observed to exist in C12A7 at high concentrations (∼1020 cm-3). The desorption of these oxygen species in C12A7 is proposed to proceed in three steps: (1) diffusion of oxygen species from bulk to the surface (rate-limiting step), (2) decomposition of oxygen species into oxygen molecules, and (3) release of molecular oxygen into the gas phase. Oxygen species in C12A7 can be regenerated by heating in an O2 atmosphere at higher than 400 °C, and the concentrations of O- and O2- increase with temperature. More O2 - is formed than O- at low activation temperatures, whereas nearly equal amounts of O- and O2- are formed at high temperatures around 1350 °C. At 400-700 °C, a considerable amount of molecular oxygen, O2, is suggested to be present together with other oxygen species. The formation of oxygen ion species occurs in a manner reverse to the desorption processes, with the first step involving diffusion of oxygen from the atmosphere into nanocages of C 12A7.

本文言語英語
ページ(範囲)104-110
ページ数7
ジャーナルChemistry of Materials
16
1
DOI
出版ステータス出版済み - 1月 13 2004
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 化学 (全般)
  • 化学工学(全般)
  • 材料化学

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