Adsorption of water vapor on the AlPO4-based catalysts and reaction mechanism for CFCs decomposition

Yusaku Takita, Jun Ichi Moriyama, Yusuke Yoshinaga, Hiroyasu Nishiguchi, Tatsumi Ishihara, Sachio Yasuda, Yusuke Ueda, Momoji Kubo, Akira Miyamoto

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Reversibly and irreversibly adsorbed water on AlPO4 and CePO4-AlPO4 (Ce/Al = 1/9) were determined by a TPD method and an electro-balance. The amounts of reversible and irreversible adsorption over AlPO4 were larger than that of CePO4-AlPO 4. However, the surface concentration of surface hydroxyls on AlPO4 was smaller than that on CePO4-AlPO4. Catalytic activity for CCl2F2 decomposition of AlPO 4 is smaller than that of CePO4-AlPO4. To explain these results, a surface intermediate, Osurface-CF 2-Osurface, is proposed. The stabilization energy was calculated for the surface species; CCl2F2 interacting with surface hydroxyls and the O-CX2-O (X = Cl or F) type surface species. The calculations suggest that P-OsurfaceH⋯Cl-CF 2-Cl⋯HOsurface-P species and Al-O surface-CF2-Osurface-Al species are the most stable. To clarify the reaction mechanism, trace amounts of by-products in the decomposition of CH2FCF3 which is hydrofluorocarbon with two carbon atoms were analyzed and found the formation of HO-CH 2CF2-OH which may be derived from the surface intermediate, Osurface-CH2CF2-O surface. This strongly supports the formation of bidentate surface intermediates.

Original languageEnglish
Pages (from-to)55-60
Number of pages6
JournalApplied Catalysis A: General
Volume271
Issue number1-2
DOIs
Publication statusPublished - 2004 Sep 10

Keywords

  • Adsorption of water vapor
  • Aluminum phosphate
  • CFCs decomposition
  • Concentration of surface hydroxyls
  • Reaction mechanism
  • Surface intermediate

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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