The passivating oxidation of platinum

Journal Article · Wed Nov 30 23:00:00 EST 1988 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(88)90039-5· OSTI ID:7121492

McCabe, R W; Wong, C ^[1]; Woo, H S ^[2]

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1. General Motors Research Laboratories, Warren, MI (USA)
2. Purdue Univ., West Lafayette, IN (USA)

The oxidation of platinum by gaseous oxygen has been studied for a series f silica and alumina-supported Pt catalysts of widely varying mean particle size. Correlation of the oxidation extent (as measured by temperature-programmed reduction) with mean particle radius (as determined from chemisorption measurements) shows that platinum oxidation is highly passivating, i.e, essentially limited to the surface layer of Pt atoms. Thus the oxidizable fraction of Pt in a catalyst sample is simply proportional to the fraction of surface Pt atoms, which explains why highly dispersed supported Pt samples oxidize more thoroughly than bulk Pt. The passivating nature of Pt oxidation is independent of both the Pt particle size (for bulk Pt down to 0.75-nm-radius particles) and the type of support (no support, silica, or alumina). The detailed structure and chemical identity of the passivating layer could not be identified; in particular, no clear distinction could be made between oxidic and chemisorbed oxygen, especially for particles with radii greater than 2 nm. Highly dispersed samples were more difficult to reduce than low-dispersion samples, possibly owing to an absence of metallic sites for H{sub 2} dissociation in the highly dispersed samples.

• OSTI ID: 7121492
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 114:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC CONVERTERS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
CONTROL
ELEMENTS
EQUIPMENT
METALS
MINERALS
NONMETALS
OXIDATION
OXIDE MINERALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PARTICLE SIZE
PLATINUM
PLATINUM METALS
POLLUTION CONTROL EQUIPMENT
REDUCTION
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SIZE
SORPTION
SURFACE PROPERTIES
TEMPERATURE CONTROL
TRANSITION ELEMENTS