The Korean Journal of Chemical Engineering

Korean Journal of Chemical Engineering,
Vol.15, No.5, 491-495, 1998

CHARACTERIZATION OF Ti/Si BINARY OXIDES PREPARED BY THE SOL-GEL METHOD AND THEIR PHOTOCATALYTIC PROPERTIES : THE HYDROGENATION AND HYDROGENOLYSIS OF CH₃CCH WITH H₂O

Yamashita H, Kawasaki S, Ichihashi Y, Takeuchi M, Harada M, Anpo M, Louis C, Che M

Titanium-silicon (Ti/Si) binary oxides having different Ti content were prepared by the sol-gel method and utilized as photocatalysts for the hydrogenation and hydrogenolysis of CH₃CCH with H₂O. The photocatalytic reactivity and selectivity of these catalysts were investigated as a function of the Ti content and it was found that the hydrogenolysis reaction (C₂H₆ formation) was predominant in regions of low Ti content, while the hydrogenation reaction (C₃H₆ formation) proceeded in regions of high Ti content. The in situ photoluminescence, diffuse reflectance absorption, FT-IR, XAFS (XANES and EXAFS), and XPS spectroscopic investigations of these Ti/Si binary oxides indicated that the titanium oxide species are highly dispersed in the SiO₂ matrices and exist in a tetrahedral coordination exhibiting a characteristic photoluminescence spectrum. The charge transfer excited state of the tetrahedrally coordinated titanium oxide species plays a significant role in the efficient photoreaction with a high selectivity for the hydrogenolysis of CH₃CCH to produces mainly C₂H₆ and CH₄, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species show a high selectivity for the hydrogenation of CH₃CCH to produce C₃H₆, being similar to reactions of the powdered TiO₂ catalysts. The good parallel relationship between the yield of the photoluminescence and the specific photocatalytic reactivity of the Ti/Si binary oxides as a function of the Ti content clearly indicates that the high photocatalytic reactivity of the Ti/Si binary oxides having low Ti content is associated with the high reactivity of the change transfer excited state of the isolated oxide species in tetrahedral coordination, [Ti³⁺-O^-].

Keywords: Photocatalysis; Titanium Oxide; Sol-Gel Method; Ti/Si Binary Oxide; Hydrogenation of Alkyne

[References]

Anpo M, Res. Chem. Intermed., 9, 67, 1989
Anpo M, Chiba K, J. Mol. Catal., 74, 207, 1992
Anpo M, Nakayama N, Kodama S, Kubokawa Y, Domen K, Onishi T, J. Phys. Chem., 90, 1633, 1986
Anpo M, Yamashita H, "Photochemistry of Surface Species Anchored on Solid Surfaces," in M. Anpo (editor), Surface Photochemistry, Wiley, West Sussex, p. 117, 1996
Anpo M, Yamashita H, "Photocatalytic Reductions - Photocatalytic Reduction of Carbon Dioxide with Water and the Hydrogenationof Unsaturated Hydrocarbons with Water," in M. Schiavello (editor), Heterogeneous Photocatalysis, Wiley, West Sussex, p. 133, 1997
Anpo M, Yamashita H, Ichihashi Y, Fujii Y, Honda M, J. Phys. Chem. B, 101(14), 2632, 1997
Camblor MA, Corma A, Perez-Pariente J, J. Chem. Soc.-Chem. Commun., 557, 1993
Moon SC, Fujino M, Yamashita H, Anpo M, J. Phys. Chem. B, 101(3), 369, 1997
Negishi N, Matsuoka M, Yamashita H, Anpo M, J. Phys. Chem., 97, 5211, 1993
Yamashita H, Ichihashi Y, Anpo M, Hashimoto M, Louis C, Che M, J. Phys. Chem., 100(40), 16041, 1996
Yamashita H, Ichihashi Y, Harada M, Stewart G, Fox MA, Anpo M, J. Catal., 158(1), 97, 1996
Yamashita H, Matsuoka M, Tsuji K, Shioya Y, Anpo M, Che M, J. Phys. Chem., 100(1), 397, 1996

[Cited By]

참고문헌정보(참고문헌, 인용문헌)는 화학공학소재연구정보센터에 의해 제공되고 있습니다.

Print:	ISSN 0256-1115
Online:	ISSN 1975-7220