Characterization of active sites and their role in gas-carbon reactions. Progress report, November 1, 1981-May 31, 1982
Rates of carbon gasification in O/sub 2/ and CO/sub 2/ are dependent upon the active surface area of the carbon. That is, only some fraction of the total surface area is active at dissociatively chemisorbing molecues of O/sub 2/ and CO/sub 2/, which is the first step leading to ultimate carbon gasification by these gases. This research is concerned about measuring the concentration of active sites on carbons varying in crystallite size and orientation (that is, all the way from microporous carbons of poor crystallinity to natural graphite flakes of high crystallinity) and relatig this concentration to gasification rates. It is seen that oxygen build-up on carbon during gasification can greatly exceed that held just on active sites, measured by oxygen chemisorption in the absence of gasification. It is attributed to spillover of oxygen from prismatic planes (active sites) onto the basal planes. Both gasification rates for the C-O/sub 2/ reaction and oxygen spillover are enhanced by the presence of a catalyst, platinum, on the carbon surface. In an effort to simplify active site characterization, an exchange reaction of oxygen between CO/sub 2//sup 18 -18/ and CO/sub 2//sup 16 -16/, over active sites, to form CO/sub 2//sup 16 -18/ was to be followed under conditions where build-up of oxygen complexes on carbon is negligible. Results of this study are reviewed.
- Research Organization:
- Pennsylvania State Univ., University Park (USA)
- DOE Contract Number:
- AC02-79ER10488
- OSTI ID:
- 5324432
- Report Number(s):
- DOE/ER/10488-3; ON: DE82017247
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400203 -- Isotope Exchange & Isotope Separation-- (-1987)
CARBON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CHALCOGENIDES
CHARS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
COAL GASIFICATION
DATA
ELEMENTS
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
GASIFICATION
INFORMATION
ISOTOPES
ISOTOPIC EXCHANGE
KINETICS
LIGHT NUCLEI
METALS
NONMETALS
NUCLEI
NUMERICAL DATA
OXIDES
OXYGEN
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PLATINUM
PLATINUM METALS
PYROLYSIS PRODUCTS
REACTION KINETICS
RESEARCH PROGRAMS
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
STABLE ISOTOPES
SURFACE AREA
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS