Chemisorption, reaction and desorption studies of coal chars in steam, oxygen and carbon dioxide. Final report, January 1986-December 1989
The use of a transient kinetics (TK) technique allowed a direct measurement of reactive surface area (RSA) for chars gasified in both CO{sub 2} and O{sub 2}, i.e., gasification rates normalized with respect to RSA were essentially constant over the entire conversion range. A temperature-programmed desorption (TPD) technique was also used to determine the amount of reactive surface intermediate formed on the chars during gasification in CO{sub 2} and O{sub 2}; the results were in good agreement with those obtained by TK. In addition, TPD allowed an important distinction to be made between the stable C-O complexes and reactive C(O) intermediates residing on the char surface during gasification in CO{sub 2} and O{sub 2}. The application of the two independent but complementary techniques provided a satisfactory quantitative understanding of char reactivity variations with conversion in CO{sub 2} and O{sub 2}. Both techniques possess the unique capability of separately determining the reaction rate constant (site reactivity or turnover frequency) and the number of active sites participating in the reaction (RSA). A comparison of turnover frequencies for different chars gasified in 1 atm CO{sub 2} suggested that char gasification may be a structure sensitive reaction. The concept of reactive surface area was also used to achieve a better quantitative understanding of catalyzed char reactivity variations with conversion in carbon dioxide.
- Research Organization:
- Pennsylvania State Univ., University Park, PA (USA). Dept. of Materials Science and Engineering
- OSTI ID:
- 6213660
- Report Number(s):
- PB-91-130252/XAB; CNN: GRI-5086-260-1419
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010404* -- Coal
Lignite
& Peat-- Gasification
ACTIVATION ENERGY
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHARS
CHEMICAL REACTION KINETICS
COAL GASIFICATION
CONTROL
DESORPTION
DOCUMENT TYPES
ELEMENTS
ENERGY
GASIFICATION
KINETICS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PROGRESS REPORT
PYROLYSIS PRODUCTS
REACTION INTERMEDIATES
REACTION KINETICS
STEAM
SURFACE AREA
SURFACE PROPERTIES
TEMPERATURE CONTROL
THERMOCHEMICAL PROCESSES
TRANSIENTS