Controlled atmosphere electron microscopy study of the gasification of graphite by water, hydrogen, and oxygen catalyzed by a nickel/potassium mixture
The gasification of graphite by H/sub 2/O vapor, wet H/sub 2/, and wet O/sub 2/, catalyzed by a Ni/K mixture is studied using controlled atmosphere electron microscopy (CAEM). In H/sub 2/O vapor the carbon consumption, between 550 and 1100/sup 0/C, is catalyzed by an edge recession mode of attack in the (1120) direction, with no sign of deactivation. An activation energy of 30.8 +/- 0.9 kcal/mol is obtained in this case. This value is similar to those obtained in kinetic studies of the steam gasification of both graphite and char, using this catalyst. In wet H/sub 2/ both channeling and edge recession occur simultaneously. The activation energy obtained is equal to 30 +/- 2 kcal/mol. The catalyst deactivates above 1000/sup 0/C, but can be regenerated by treating the sample in H/sub 2/ vapor at 600/sup 0/C. In wet O/sub 2/ graphite is also gasified by edge recession, but no preferred direction is observed. The catalyst maintains its activity up to 1000/sup 0/C, and an activation energy of 25 +/- 2 kcal/mol is obtained. These results show that the catalytic properties of the Ni/K mixture are superior to those of Ni and K alone due to a cooperative effect between the components. 20 references.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 5298431
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 110:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010404* -- Coal
Lignite
& Peat-- Gasification
ACTIVATION ENERGY
ALKALI METALS
CARBON
CATALYTIC EFFECTS
CHARS
CHEMICAL REACTION KINETICS
COAL GASIFICATION
CRYSTAL STRUCTURE
DEACTIVATION
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
ENERGY
GASIFICATION
GRAPHITE
HYDROGEN
HYDROGEN COMPOUNDS
KINETICS
METALS
MICROSCOPY
MINERALS
MIXTURES
NICKEL
NONMETALS
OXYGEN
OXYGEN COMPOUNDS
POTASSIUM
PYROLYSIS PRODUCTS
REACTION KINETICS
REGENERATION
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
WATER