T. Mitsudo, J. Chem. Soc., Faraday T rans., 1998, 94, 1771.
S. Yoshida, T. Tanaka, M. Okada and T. Funabiki, J. Chem.
Soc., Faraday T rans. 1, 1984, 80, 119; H. Kobayashi, M. Yama-
guchi, T. Tanaka and S. Yoshida, J. Chem. Soc., Faraday T rans.
1, 1985, 81, 1513.
T. Tanaka, M. Ooe, T. Funabiki and S. Yoshida, J. Chem. Soc.,
Faraday T rans. 1, 1986, 82, 35; Y. Nishimura and S. Yoshida, in
Computer Aided Innovation of New Materials II, ed. M. Doyama,
J. Kihara, M. Tanaka and R. Yamamoto, Elsevier, Amsterdam,
1993, p. 1029.
4
5
6
S. Yoshida, Y. Nishimura, T. Tanaka and T. Funabiki, Catal.
T oday, 1990, 8, 67; T. Tanaka, H. Nojima, H. Yoshida, H. Naka-
gawa, T. Funabiki and S. Yoshida, Catal. T oday, 1993, 16, 297.
T. Tanaka, Y. Nishimura, S. Kawasaki, M. Ooe, T. Funabiki and
S. Yoshida, J. Catal., 1989, 118, 32.
7
8
9
Fig. 10 Possible reaction scheme for the initial stage of CO photo-
oxidation over Ta O ÈSiO .
T. Tanaka, S. Takenaka, T. Funabiki and S. Yoshida, Chem.
L ett., 1994, 809.
2
5
2
S. Yoshida, Y. Matsumura, S. Noda and T. Funabiki, J. Chem.
Soc., Faraday T rans. 1, 1981, 77, 2237.
was not detected. The presence of an O ÈCO intermediate is
one of the candidates which can explain the isotope distribu-
3
10 A. M. Gritzkov, V. A. Shvets and V. B. Kazansky, Chem. Phys.
L ett., 1975, 35, 511; M. Anpo, I. Tanahashi and Y. Kubokawa, J.
Phys. Chem., 1980, 84, 3440.
11 D. L. Nguyen, P. C. Roberge and S. Kalliaguin, Can. J. Chem.
Eng., 1979, 57, 2880; S. Kalliaguin, M. Guakoury and P. C.
Roberge, Can. J. Chem. Eng., 1981, 59, 710.
tion in the carbon dioxide formed from C16O and 18O .
2
Conclusion
12 T. Tanaka, S. Takenaka, T. Funabiki and S. Yoshida, in AcidÈ
Base Catalysis II (Proceedings of International Symposium on
AcidÈBase Catalysis 2, Sapporo, 1993), ed. H. Hattori, M. Misono
and Y. Ono, Kodansha, Tokyo, 1994, p. 485.
13 T. Uruga, H. Tanida, Y. Yoneda, K. Takeshita, S. Emura, M.
Takahashi, M. Harada, Y. Nishihata, Y. Kubozono, T. Tanaka,
T. Yamamoto, H. Maeda, O. Kamishima, Y. Takabayashi, Y.
Nakata, H. Kimura, S. Goto and T. Ishikawa, J. Synchrotron
Radiat., 1999, 6, 143.
14 T. Tanaka, H. Yamashita, R. Tsuchitani, T. Funabiki and S.
Yoshida, J. Chem. Soc., Faraday T rans. 1, 1988, 84, 2987.
15 G. Martens, P. Rabe, N. Schwentner and A. Werner, Phys. Rev.
L ett., 1977, 39, 1411.
16 J. A. Horsley, I. E. Wachs, J. M. Brown, G. H. Via and F. D.
Hardcastle, J. Phys. Chem., 1987, 91, 4014.
17 S. Yoshida, T. Tanaka, T. Hanada, T. Hiraiwa, H. Kanai and T.
Funabiki, Catal. L ett., 1992, 12, 277.
18 S. Yoshida, T. Tanaka, Y. Nishimura, H. Mizutani and T. Fun-
abiki, in Catalysis, T heory to Practice (Proceedings of 9th Interna-
tional Congress on Catalysis, 1988), ed. M. J. Phillips and M.
Ternan, Chemical Institute of Canada, Calgary, ON, 1988, vol. 3,
p. 1473.
Tantalum oxide (10 wt.%) is supported on silica in a highly
dispersed form. The structure of the surface tantalum species
is the same as that of vanadium and niobium oxides; a Ta ion
is located at a center of an oxygen tetrahedron, one of which
forms a Ta2O bond. The Ta2O species is photoactive but ter-
minal oxygen does not participate directly in oxidation of CO,
as elucidated by photoluminescence spectroscopy. The active
species is an adsorbed oxygen molecule interacting with a
photoexcited lattice oxygen to form a T-type ozonide ion. The
ozonide ions are attacked by a CO molecule to form an
O ÈCO intermediate.
3
Acknowledgements
The X-ray absorption experiment was carried out under the
approval of JASRI (proposal no. 1999A0083). We thank Drs.
T. Uruga and H. Tanida at JASRI for their aid in collecting
XAFS spectra.
19 H. Yoshida, T. Tanaka, T. Yoshida, T. Funabiki and S. Yoshida,
Catal. T oday, 1996, 28, 79.
20 T. Tanaka, H. Yoshida, K. Nakatsuka, T. Funabiki and S.
Yoshida, J. Chem. Soc., Faraday T rans., 1992, 88, 2297.
21 H. Yoshida, T. Tanaka, T. Funabiki and S. Yoshida, J. Chem.
Soc., Faraday T rans., 1994, 90, 2107.
References
1
S. Kalliaguin, B. N. Shelimov and V. B. Kazansky, J. Catal.,
1978, 55, 384.
2
T. Tanaka, S. Takenaka, T. Funabiki and S. Yoshida, Chem.
L ett., 1994, 1585; S. Takenaka, T. Kuriyama, T. Tanaka, T. Fun-
abiki and S. Yoshida, J. Catal., 1995, 155, 196; T. Tanaka, S.
Takenaka, T. Funabiki, and S. Yoshida, J. Chem. Soc., Faraday
T rans., 1996, 92, 1975; S. Takenaka, T. Tanaka, T. Funabiki and
S. Yoshida, Catal. L ett., 1997, 44, 67; S. Takenaka, T. Tanaka, T.
Yamazaki, T. Funabiki and S. Yoshida, J. Phys. Chem. B, 1997,
101, 9035; S. Takenaka, T. Tanaka, T. Funabiki and S. Yoshida,
J. Chem. Soc., Faraday T rans., 1997, 93, 4151.
22 M. Che and A. J. Tench, Adv. Catal., 1983, 32, 1.
23 A. R. Gonzalez-Elipe, C. Louis and M. Che, J. Chem. Soc.,
Faraday T rans. 1, 1982, 78, 1297.
24 A. Ogata, A. Kazusaka and M. Enyo, J. Phys. Chem., 1986, 90,
5201.
25 Y. Ben Taarit, J. C. Vedrine, C. Naccache, Ph. de MontgolÐer
and P. Meriaudeau, J. Chem. Phys., 1970, 64, 2880.
3
K. Wada and Y. Watanabe, in Methane and Alkane Conversion
Chemistry, ed. M. M. Bhasin and D. W. Slocum, Plenum Press,
Paper 9/05102C
Phys. Chem. Chem. Phys., 1999, 1, 5235È5239
5239