The influence of catalyst surface structure on activity and selectivity reforming reactions of heptane and cyclohexane on platinum crystals
Heptane aromatization and cyclohexane dehydrogenation and hydrogenolysis were carried out on a flat platinum (111) (C) surface and stepped platinum (S)-(6(111)x(100)) (A) and platinum (S)-(3(111)x(100)) (B) surfaces at 5-80 mm Hg hydrocarbon pressure, 0-600 mm Hg hydrogen pressure, and 220/sup 0/-340/sup 0/C crystal temperature. The C and A surfaces had about the same initial activity for n-heptane aromatization to toluene, but the C surface deactivated rapidly. The activity of the B surface was half that of the A surface and was very stable over three hours. The A surface could be deactivated rapidly at lower hydrogen pressures, higher n-heptane pressures, and higher temperatures. Cyclohexane dehydrogenation to benzene decreased in the order B > C > A, and carbon coverage increased with step density in the order C < A < B. The rate of cyclohexene production increased after about one hour. Carbonaceous overlayers affected the platinum activity and selectivity and must be considered integral parts of catalyst surfaces.
- OSTI ID:
- 6020241
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
ALKENES
AROMATIZATION
CATALYSTS
CATALYTIC REFORMING
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
CYCLOALKANES
CYCLOALKENES
CYCLOHEXANE
DEACTIVATION
DECOMPOSITION
DEHYDROGENATION
ELEMENTS
HEPTANE
HIGH TEMPERATURE
HYDROCARBONS
HYDROLYSIS
LOW PRESSURE
LYSIS
METALS
MONITORING
ORGANIC COMPOUNDS
PLATINUM
PLATINUM METALS
REFORMER PROCESSES
SOLVOLYSIS
SURFACE PROPERTIES
TRANSITION ELEMENTS