Reaction of carbon and water as catalyzed by nickel and iron surfaces
The individual steps of the reaction of carbon and water to produce CO and H/sub 2/ were quantified on nickel and iron surfaces using temperature-programmed reaction spectroscopy (TPRS), Auger electron spectroscopy (AES), Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). Surface graphite and carbide, two metastable surface carbon forms, were prepared by dehydrogenation of C/sub 2/H/sub 2/ and served as reactant carbon. UPS of the graphite monolayer in contact with the metal yielded a valence electronic structure that could be interpreted in terms of the bulk band structure of graphite. The CO formation step is rate limiting in the uncatalyzed H/sub 2/O gasification reaction of graphite. The nickel surface in contact with graphitic carbon lowers the barrier for the CO formation step. The catalytic action occurs directly without isolated prior breaking of carbon-carbon bonds. The estimated activation energy for the direct reaction was 44 kcal/mole. The fully carbided surfaces of Ni and Fe were active for H/sub 2/O dissociation with an estimated activation energy between 5.0 and 10.0 kcal/mole. A different catalytic reaction cycle involving carbon-carbon bond breaking followed by oxidation of the carbide is energetically more demanding. The activation energy for direct carbon-carbon bond breaking was estimated between 65-70 kcal/mole on both nickel and iron. Following this demanding step, the reaction between carbidic carbon and oxygen proceeded on nickel and iron with estimated activation energies of 31 and 39 kcal/mole, respectively. This indirect carbide reaction cycle changed the energetics of the steam gasification of carbon.
- Research Organization:
- Rutgers--the State Univ., New Brunswick, NJ (USA)
- OSTI ID:
- 7017377
- Country of Publication:
- United States
- Language:
- English
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ACTIVATION ENERGY
AUGER ELECTRON SPECTROSCOPY
CARBIDES
CARBON
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
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COAL GASIFICATION
ELECTRON SPECTROSCOPY
ELEMENTAL MINERALS
ELEMENTS
ENERGY
GASIFICATION
GRAPHITE
HYDROGEN
HYDROGEN PRODUCTION
IRON
KINETICS
METALS
MINERALS
NICKEL
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
REACTION KINETICS
SPECTRA
SPECTROSCOPY
STEAM
STEAM-IRON PROCESS
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
ULTRAVIOLET SPECTRA
X-RAY SPECTROSCOPY