Dispersion and structure of platinum-iridium catalysts
The catalysts contained 0.6-20Vertical Bar3< by wt of an equal amount (by wt) of platinum and iridium, or of either metal alone, on alumina or silica. Hydrogen chemisorption indicated that the catalyst had a higher degree of dispersion on alumina than on silica. At low metal loadings, adsorbed hydrogen atom to metal atom ratios increased to 1.7:1, probably owing to a change in adsorption stoichiometry at high dispersion and not to hydrogen spillover. Bimetallic clusters of 27-49 A. were detected by X-ray diffraction of 5-20Vertical Bar3< platinum/iridium on silica. Calcination in air at 500/sup 0/C caused oxidation of iridium and agglomeration of large IrO/sub 2/ crystallites, which were reduced to large iridium crystallites in subsequent reduction.
- Research Organization:
- Exxon Res. Eng. Co.
- OSTI ID:
- 6922941
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 56:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CALCINATION
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
CONCENTRATION RATIO
CRYSTAL STRUCTURE
DATA
DECOMPOSITION
DIFFRACTION
DISPERSIONS
ELEMENTS
EXPERIMENTAL DATA
HYDROGEN
INFORMATION
IRIDIUM
METALS
MINERALS
NONMETALS
NUMERICAL DATA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
PYROLYSIS
QUANTITY RATIO
SCATTERING
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SOLID CLUSTERS
SORPTION
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
X-RAY DIFFRACTION