Mechanism and structure sensitivity of propane hydrogenolysis over Ni/SiO/sub 2/ catalysts
An experimental kinetic study showed that propane hydrogenolysis over nickel is proportional to (1-h/sub h/)/sup x/, which is the probability of finding at least x adjacent nickel atoms free from adsorbed hydrogen. These ensembles of x adjacent hydrogen-free nickel atoms were apparently the active sites. For the reaction of propane and hydrogen to methane and ethane, x was 17 and the activation energy was 14 +/- 3 kcal/mole. For the hydrogenolysis reaction that yields three methane molecules, x was 24 and the activation energy was 9 kcal/mole. The rate coefficient was of the same order of magnitude as the number of propane molecules colliding with the nickel surface per unit time. The rate-limiting step was the formation of strongly dehydrogenated and cracked surface species on the nickel atom ensembles, as previously suggested for the ethane hydrogenolysis The reaction was structure insensitive except for the (111) planes, which were less active for propane hydrogenolysis than y for ethane hydrogenolysis.
- Research Organization:
- C.N.R.S., Inst. Rech. Catal., Villeurbanne
- OSTI ID:
- 6319850
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 62:2; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
DATA
ELEMENTS
ENERGY
ETHANE
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
KINETICS
METALS
METHANE
NICKEL
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PROPANE
REACTION KINETICS
SURFACE PROPERTIES
TRANSITION ELEMENTS
YIELDS