Influence of carrier and oxygen treatment on the catalytic behavior of supported platinum-gold alloys
Catalysts containing 15% loading of 4% Pt-Au alloy on silica or ..gamma..-alumina were prepared by co-reduction with hydrazine, reduced in hydrogen, and tested for activity for n-hexane isomerization and cyclization at 350/sup 0/C. The catalysts were then subjected to two oxidation-reduction cycles, and tested with the same reaction. Over alumina-supported alloy, the initial conversion was 2.9%/g catalyst and the selectivities for isomerization and cyclization were approx. 90 and approx. 5%, respectively. After the oxidation-reduction treatment, conversion was 6.0%/g catalyst, and isomerization and cyclization selectivities were 30 and 56%, respectively. The silica-supported alloy had similar initial activity and selectivity as the alumina-supported catalyst, but did not change significantly on oxidation-reduction. A comparison with pure platinum on the same carriers suggested that the platinum segregated from the alloy during oxygen treatment and formed platinum oxide, that the platinum oxide migrated to the alumina surface where it formed separate particles on reduction, but it was unable to ''wet'' the silica surface and migrated to the alloy particle surface in the silica-supported catalyst, where it forms bulk alloy again, on reduction.
- Research Organization:
- Rijksuniv. Leiden
- OSTI ID:
- 6458215
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 64:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400300 -- Organic Chemistry-- (-1987)
ALKANES
ALLOYS
ALUMINATES
ALUMINIUM COMPOUNDS
CARRIERS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHEMICAL ACTIVATION
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
DEHYDROCYCLIZATION
GOLD ALLOYS
HEXANE
HYDROCARBONS
ISOMERIZATION
ORGANIC COMPOUNDS
OXIDATION
OXYGEN COMPOUNDS
PLATINUM ALLOYS
PLATINUM METAL ALLOYS
REDUCTION
SILICATES
SILICON COMPOUNDS
SYNTHESIS