Importance of active sites for char gasification in oxygen (air) and carbon dioxide. Final report, October 1982-September 1987
The principal objective of the research program was to study the influence of carbon active sites and catalysis on gasification reactivities of coals and coal chars. Specific emphasis was given to determining the applicability of attempts to measure active-site concentration. Both isothermal and non-isothermal reactivities in air and carbon dioxide clearly indicate that for coals the reactivities decrease as the rank of coal increases. It has shown that for highly disordered chars, reactivity profiles measured by both IR and TGA methods differ for the early stages of burn-off. These differences are a result of surface oxygen complexes. Oxygen-chemisorption kinetics on selected samples in the absence of gasification have shown that chemisorption essentially occurs on highly active carbon sites. For calcium-loaded samples, the amount of oxygen chemisorbed at the same temperature is almost four times higher than that for 'pure' carbon, which indicates that the oxygen spillover from calcium onto carbon occurs. Additionally, it has been shown that the carbon active sites are energetically heterogeneous. Because of this heterogeneity, normalization of reactivity based upon a simple active surface area measured as a total stable oxygen complex was unsuccessful.
- Research Organization:
- Pennsylvania State Univ., University Park, PA (USA). Dept. of Materials Science and Engineering
- OSTI ID:
- 5864874
- Report Number(s):
- PB-89-195796/XAB
- Country of Publication:
- United States
- Language:
- English
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Lignite
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ALKALINE EARTH METALS
CALCIUM
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHARS
CHEMICAL REACTIONS
CHEMISORPTION
COAL GASIFICATION
DOCUMENT TYPES
ELEMENTS
GASIFICATION
ISOTHERMAL PROCESSES
KINETICS
METALS
OXIDES
OXYGEN COMPOUNDS
PROGRESS REPORT
PYROLYSIS PRODUCTS
SEPARATION PROCESSES
SORPTION
THERMOCHEMICAL PROCESSES