Further studies of the nickel/graphite-hydrogen reaction
A combination of electron microscopy and hydrogen chemisorption techniques has been used to probe the causes for the unusual loss in catalytic activity of nickel particles in the graphite-hydrogen reaction. This deactivation, which occurs at about 1000/sup 0/C, is associated with the spreading of material along the sides of channels created catalytically at lower temperatures. Detailed quantitative analysis of this phenomenon indicates that nickel is progessively laid down as a near-monolayer film on the walls of the channels while the particles move forward. Nickel deposited in this manner strongly interacts with hydrogen ''sorbed'' by the graphite and therefore has a poor activity for C-C bond rupture (carbon gasification) and a low hydrogen chemisorption capacity. Removal of ''sorbed'' hydrogen at 1000/sup 0/C, under vacuum or in inert gas environments, not only results in carbon gasification, but also in removal of Ni-H interactions and formation of Ni-C bonds (a surface carbide which does not adsorb H/sub 2/). These Ni-C bonds are broken by steaming at 1000/sup 0/C and the hydrogen chemisorption capacity is restored.
- Research Organization:
- Exxon Research and Engineering Co., Linden, NJ
- OSTI ID:
- 6847407
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 75:2; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CARBON
CATALYTIC EFFECTS
CHEMICAL REACTIONS
CHEMISORPTION
DATA
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
EXPERIMENTAL DATA
GASIFICATION
GRAPHITE
HIGH TEMPERATURE
HYDROGEN
INFORMATION
LOW PRESSURE
METALS
MICROSCOPY
MINERALS
NICKEL
NONMETALS
NUMERICAL DATA
SEPARATION PROCESSES
SORPTION
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE