Photocatalytic oxidation of CO with various oxidants by Mo oxide species highly dispersed on SiO2 at 293 K |
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Authors: | Takashi Kamegawa Rumi Takeuchi Masaya Matsuoka Masakazu Anpo |
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Affiliation: | Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan |
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Abstract: | The photocatalytic oxidation of CO into CO2 with oxidants such as NO, N2O and O2 proceeded efficiently on a Mo/SiO2 with high Mo dispersion under UV light irradiation. It was found that the reaction rate greatly depended on the kind and concentration of the oxidant. Photoluminescence investigations reveal the close relationship between the reaction rate and the relative concentration of the photo-excited Mo6+-oxide species, i.e. charge transfer–excited–triplet state (Mo5+–O−)*, under steady-state reaction conditions. Moreover, the photocatalytic oxidation of CO with O2 in excess H2 was carried out to test suitability for applications to supplying pure H2. This reaction was seen to proceed efficiently on Mo/SiO2 with a high CO conversion of 100% and CO selectivity of 99% after 180 min under UV light irradiation, showing higher photocatalytic performance than TiO2 (P-25) photocatalyst. UV–vis, XAFS, photoluminescence and FT-IR investigations revealed that the high reactivity of the charge transfer–excited–triplet state (Mo5+–O−)*, with CO as well as the high reactivity of the photoreduced Mo-oxide species (Mo4+-species) with O2 to produce the original Mo-oxide species (Mo6+O2−), played a crucial role in the reactions. |
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Keywords: | Photocatalytic oxidation of CO Mo/SiO2 catalyst TiO2 (P-25) Preferential oxidation of CO in H2 Redox cycles Photoluminescence |
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