Oxidation of carbon monoxide over palladium on zirconia prepared from amorphous Pd-Zr alloy. 1. Bulk structural, morphological, and catalytic properties of catalyst

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(90)90020-K· OSTI ID:5618988

Baiker, A; Gasser, D; Lenzner, J ^[1]; Reller, A ^[2]; Schloegl, R ^[3]

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1. Swiss Federal Institute of Technology, Zurich (Switzerland)
2. Univ. of Zurich (Switzerland)
3. Fritz Haber Institute der Max Planck Gesellschaft, Berlin (Germany)

Catalysts highly active for the oxidation of carbon monoxide have been prepared by oxidation of amorphous and crystalline Pd{sub 1}Zr{sub 2} metal alloys. The oxidation was carried out in situ; i.e., the fresh metal alloys were exposed to CO-oxidation conditions at temperature of 473-553 K. Under these conditions, the initially almost inactive metal alloys underwent a series of solid state reactions and were finally transformed into stable and highly active microporous catalysts. Bulk structural characterization using X-ray diffraction and electron microscopy revealed that the final catalysts were made up of small intergrown and poorly crystalline domains of different palladium and zirconia phases. Palladium was present in three forms in the active catalysts, as a solid solution of palladium and oxygen, as metallic palladium, and a PdO. Zirconia existed in monoclinic and tetragonal forms. Comparative kinetic measurements carried out in a differential fixed bed reactor in the temperature range 300-500 K indicated that the activity of the palladium species in the catalysts derived from the metal alloys was more than an order of magnitude higher than the activity of the palladium species in a palladium on zirconia catalyst prepared by impregnation. The comparison of the activities was based on turnover frequencies calculated on the basis of accessible palladium sites determined by CO chemisorption. The higher activity of the catalysts derived from the metal alloys is attributed to their unique structural and chemical properties leading to extremely large interfacial areas and possibly to enhanced oxygen transfer via the solid-solid interphase.

• OSTI ID: 5618988
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 126:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330702 -- Emission Control-- Carbon Monoxide
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AIR POLLUTION CONTROL
ALLOYS
BIMETALS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
CONTROL
CRYSTAL STRUCTURE
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTS
GASEOUS WASTES
IMPREGNATION
INTERMETALLIC COMPOUNDS
METALS
MICROSCOPY
MIXTURES
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PALLADIUM ALLOYS
PALLADIUM COMPOUNDS
PALLADIUM OXIDES
PLATINUM METAL ALLOYS
PLATINUM METALS
POLLUTION CONTROL
SCATTERING
SEPARATION PROCESSES
SOLID SOLUTIONS
SOLUTIONS
SORPTION
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
WASTES
X-RAY DIFFRACTION
ZIRCONIUM ALLOYS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES