Carbon monoxide oxidation over catalysts prepared by in situ activation of amorphous gold-silver-zirconium and gold-iron-zirconium alloys

Journal Article · Wed Feb 01 00:00:00 EST 1995 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1995.1043· OSTI ID:175728

Baiker, A; Maciejewski, M; Tagliaferri, S ^[1]

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1. Swiss Federal Institute of Technology, Zuerich (Switzerland); and others

Amorphous metal alloys with the compositions (at. %) Au{sub 5}FeZr{sub 14} and Au{sub 5}AgZr{sub 14} have been used as precursors for the preparation of gold-zirconia-iron oxide and gold-silver-zirconia catalysts for low-temperature CO oxidation. The catalysts were prepared by in situ activation (oxidation) of the glassy metal alloys under CO oxidation conditions at 280{degrees}C. The structural and chemical changes occurring during the transformation of the precursor alloys to the active stable catalysts were followed by thermal analysis, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. When exposed to CO reaction conditions, the glassy metal alloys exhibited initially very little activity due to the very low surface area of the alloys (<0.02 m{sup 2}/g). The activity developed with time on stream reaching a steady state after complete oxidation of the alloys. The stable active catalyst derived from Au{sub 5}FeZr{sub 14} was made up of gold particles supported on zirconia in which the iron oxide was dispersed. The catalyst prepared from Au{sub 5}AgZr{sub 14} contained gold-silver particles supported on zirconia. The zirconia formed by oxidation of the zirconium constituent was present in both catalysts as a mixture of poorly crystalline monoclinic and tetragonal phases. Both catalysts were microporous with BET surface areas of 30 mg{sup 2}/g (Au{sub 5}FeZr{sub 14}) and 45 m{sup 2}/g (Au{sub 5}AgZr{sub 14}). Kinetic tests performed in a continuous tubular microreactor in the temperature range from -20 to 50{degrees}C showed that both catalysts are highly active for CO oxidation at low temperature. CO oxidation rates increased considerably if the CO:O{sub 2} ratio in the reactant feed was changed from stoichiometry (2:1) to conditions of excess oxygen (1:2). 33 refs., 13 figs., 1 tab.

• OSTI ID: 175728
• Journal Information: Journal of Catalysis, Vol. 151, Issue 2; Other Information: PBD: Feb 1995
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
33 ADVANCED PROPULSION SYSTEMS
CARBON MONOXIDE
OXIDATION
GOLD
CATALYTIC EFFECTS
SILVER
ZIRCONIUM OXIDES
IRON
CATALYSTS
CATALYST SUPPORTS
MONOCLINIC LATTICES
TETRAGONAL LATTICES
THERMAL ANALYSIS
X-RAY DIFFRACTION
SCANNING ELECTRON MICROSCOPY
X-RAY SPECTROSCOPY
PHOTOELECTRON SPECTROSCOPY
CONCENTRATION RATIO
CHEMICAL REACTION KINETICS