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The photocatalytic reactivities of chromium oxide (Cr-oxide) loaded on zeolites and mesoporous molecular sieves by an impregnation method have been investigated. The Cr-oxide impregnated on mesoporous silica (imp-Cr/HMS) involves tetrahedrally-coordinated Cr-oxide moieties with two terminal Cr=O. The imp-Cr/zeolite contains a mixture of tetrahedrallyand octahedrally-coordinated Cr-oxide species (Cr 2 O 3 -like cluster). In the presence of propane and O 2 , a partial oxidation of propane with a high selectivity for acetone formation proceeded on imp-Cr/HMS under visible light irradiation, while a low reactivity was observed on imp-Cr/zeolites. The charge transfer excited state of the tetrahedrally-coordinated Cr-oxide moieties plays a significant role in the photocatalytic reactions.

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Using a photo-assisted deposition method, a tetrahedrally coordinated chromium oxide moieties (tetra-Cr oxide) can be anchored on a tetrahedrally coordinated titanium oxide moieties (tetra-Ti oxide) included within a framework of mesoporous silica. Under UV-light irradiation, the tetra-Cr oxide moieties can be deposited on the photo-excited tetra-Ti oxide moieties forming a direct interaction. This catalyst can demonstrate as a photocatalyst having the high efficiency and the high selectivity in the photoepoxidation of propene with O2 under visible light irradiation.