Influence of alloying Pt with Cu on the reaction mechanisms of hydrocarbon reforming reactions. [2-methylpentane-2-carbon 13, 2-methylpentane-4-carbon 13, 3-methylpentane-3-carbon-13]
The mechanism of the suppression of isomerization in hydrocarbon reforming on platinum-copper catalysts was studied with 2-methylpentane-2-carbon-13, 2-methylpentane-4-carbon-13, and 3-methylpentane-3-carbon-13 on silica-supported platinum-copper catalysts containing 0-100% copper. Product and isomer distributions obtained in tests with squarewave pulses (about one minute) of approx. 5 mg labeled alkane in hydrogen at 330/sup 0/C and 1 atm showed that with increasing copper content the activity decreased rapidly to near zero at approx. 50% copper, the selectivity isomerization decreased, hydrogenolytic cracking increased at Cu > 25%, and dehydrocyclization had weak maximum at approx. 25% Cu and a shallow minimum at approx. 50% Cu. An analysis of the contributions of the ''bond-shift'' mechanism involving three carbon atoms and the ''cyclic'' mechanism involving five carbons to isomerization showed that the effects of copper are geometric and/or electronic ensemble size effects, i.e., at 75-100% Pt, multisite bond-shift and selective cyclization mechanisms occur, but at 45-75% Pt, the bond-shift mechanism disappears and a nonselective single-site cyclic mechanism becomes important.
- Research Organization:
- Rijksuniv. Leiden
- OSTI ID:
- 6462308
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 63:2; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALLOYS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COPPER ALLOYS
HYDROCARBONS
INHIBITION
ISOMERIZATION
ISOTOPE APPLICATIONS
KINETICS
METALLURGICAL EFFECTS
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM ALLOYS
PLATINUM METAL ALLOYS
REACTION KINETICS
REFORMER PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
TRACER TECHNIQUES