Reactions of neopentane and neohexane on platinum/Y-zeolite and platinum/silica catalysts
The hydrocracking/hydroisomerization reaction of 20:1 hydrogen/neopentane at 455-625/sup 0/K was studied on platinum-exchanged sodium, calcium, and lanthanum Y zeolites and Aerosil-supported platinum of 1-20 nm average platinum particle size, by analysis of the product distribution, ESCA, and temperature-programed desorption. The results suggested that the reaction occurs only on platinum and that it proceeds by two parallel pathways which have different activation energies and whose relative proportion depends on the particle size. One pathway is the conventionally accepted one on low-index crystallite facets; the other proceeds on single-surface platinum atoms of low coordination (corner or edge atoms) which become more abundant at lower crystallite size. In both cases, the adsorbed intermediate may undergo either isomerization or hydrogenolysis; the selectivity depends on the hydrogen partial pressure and the relative strength of adsorption of hydrogen and neopentane. Neohexane isomerization selectivity on the same catalysts is consistent with a carbonium ion mechanism on a dual-function catalyst.
- Research Organization:
- Univ. of Melbourne
- OSTI ID:
- 7138660
- Journal Information:
- J. Catal.; (United States), Vol. 54:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
2-2-DIMETHYLPROPANE
HYDROCRACKING
ISOMERIZATION
ALKANES
PLATINUM
CATALYTIC EFFECTS
ZEOLITES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
HIGH TEMPERATURE
PARTICLE SIZE
CRACKING
DECOMPOSITION
ELEMENTS
HYDROCARBONS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETICS
MATERIALS
METALS
MINERALS
ORGANIC COMPOUNDS
PLATINUM METALS
PYROLYSIS
REACTION KINETICS
SIZE
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400201 - Chemical & Physicochemical Properties