期刊
APPLIED CATALYSIS A-GENERAL
卷 291, 期 1-2, 页码 126-135出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apcata.2005.02.048
关键词
gold; cerium oxide; water-gas shift; selective CO oxidation; temperature-programmed reduction; redox; fuel cells; preferential oxidation of carbon monoxide
Low-content (<0.6 at.%) gold-ceria samples were prepared by one-pot synthesis by the urea gelation/co-precipitation method, and by sodium cyanide leaching of high-content (5 at.%) gold-ceria materials prepared by deposition-precipitation. These catalysts, containing cationic gold in ceria, are active for both the low-temperature water-gas shift (WGS) reaction and the preferential oxidation of CO (PROX). The surface oxygen of ceria, as estimated by H-2-TPR, was used to normalize the WGS reaction rates. Cyclic temperature-programmed reduction with intermittent reoxidation showed that the surface structures of gold-ceria catalysts are highly reversible. Considerable reoxidation by oxygen or H2O can occur even at ambient conditions. The stability of low-content gold-ceria catalysts for the PROX reaction in a realistic fuel gas mixture containing 1% CO-0.5% O-2-50% H-2-10% H2O-15% CO2-He was excellent. No drop in activity or selectivity was found in cyclic operation up to 150 degrees C. (c) 2005 Elsevier B.V. All rights reserved.
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