TY - JOUR
T1 - Adsorption of water vapor on the AlPO4-based catalysts and reaction mechanism for CFCs decomposition
AU - Takita, Yusaku
AU - Moriyama, Jun Ichi
AU - Yoshinaga, Yusuke
AU - Nishiguchi, Hiroyasu
AU - Ishihara, Tatsumi
AU - Yasuda, Sachio
AU - Ueda, Yusuke
AU - Kubo, Momoji
AU - Miyamoto, Akira
PY - 2004/9/10
Y1 - 2004/9/10
N2 - 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.
AB - 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.
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U2 - 10.1016/j.apcata.2004.02.046
DO - 10.1016/j.apcata.2004.02.046
M3 - Article
AN - SCOPUS:3242722120
SN - 0926-860X
VL - 271
SP - 55
EP - 60
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 1-2
ER -