Dynamic study of the oxidation state of copper in the course of carbon monoxide oxidation over powdered CuO and Cu{sub 2}O
Variations in the oxidation state of copper during CO catalytic oxidation over powdered CuO and Cu{sub 2}O in a gas mixture of 5% CO/He and air (O{sub 2}) were investigated by means of an appropriate combination of evolved gas analysis, thermogravimetry, XRD, and FT-IR in the temperature range of RT to 350 C, and these variations were compared with those observed when both oxides were individually reacted with CO (5% CO/He) and with air. The catalytic rate over CuO was found to almost agree with the bulk reduction rate of CuO {yields} Cu, while the catalytic rate over Cu{sub 2}O agreed with the bulk reduction rate of CuO{sup {minus}} {yields} Cu{sub 2}O, where CuO* denotes a metastable divalent copper oxide produced in the oxidizing process of Cu{sub 2}O. Adsorption of O{sub 2}{sup {minus}} and/or O{sup {minus}} was characteristic of CuO*, in contrast with that of O{sub 2} and/or O of CuO. Variations in copper valence of a catalyst surface are discussed.
- Research Organization:
- Tohoku Univ., Sendai (JP)
- OSTI ID:
- 20000963
- Journal Information:
- Journal of Catalysis, Vol. 187, Issue 1; Other Information: PBD: 1 Oct 1999; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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