Surface interactions in the Pt/. gamma. -Al/sub 2/O/sub 3/ system
Catalysts containing 0.78-23.1% by wt platinum on alumina were studied by BET area determinations, hydrogen and carbon monoxide adsorption, temperature-programed hydrogen reduction, and transmission electron microscopy. Two oxide phases of platinum were detected: a particulate phase without platinum-support interaction, which was reduced at approx. 10/sup 0/C, and which probably consisted of a mixture of PtO/sub 2/, PtO, and metallic Pt; and a dispersed phase, which interacted with the support and was reduced at 90/sup 0/-250/sup 0/C depending on loading, consisted only of PtO/sub 2/, and apparently formed the alumina-platinum complexes reported to be soluble in acetylacetone and acid. The dispersed phase was the only phase detected at low loadings (to approx. 2.2 jmole/sq m); above the dispersion limit, which corresponded to approx. 15% coverage of the alumina support, the platinum oxide aggregated to form crystallites. Heat treatment in hydrogen at various temperatures and in oxygen above 600/sup 0/C reduced the dispersed oxide to form aggregated metallic platinum, except treatment in hydrogen at 300/sup 0/C which formed dispersed metallic platinum.
- Research Organization:
- Ford Motor Co.
- OSTI ID:
- 6199780
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 59:3; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ADSORPTION
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTS
HEAT TREATMENTS
HYDROGEN
METALS
MICROSCOPY
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PLATINUM
PLATINUM METALS
SORPTION
STRUCTURAL CHEMICAL ANALYSIS
SURFACE PROPERTIES
SURFACES
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY