Structural evolution of carbon during oxidation. Final report
The examination of the structural evolution of carbon during oxidation has proven to be of scientific interest. Early modeling work of fluidized bed combustion showed that most of the reactions of interest occurs in the micropores, and this work has concentrated on these pores. This work has concentrated on evolution of macroporosity and microporosity of carbons during kinetic controlled oxidation using SAXS, CO{sub 2} and TEM analysis. Simple studies of fluidized bed combustion of coal chars has shown that many of the events considered fragmentation events previously may in fact be {open_quotes}hidden{close_quotes} or nonaccessible porosity. This makes the study of the microporous combustion characteristics of carbon even more important. The generation of a combustion resistant grid, coupled with measurements of the SAXS and CO{sub 2} surface areas, fractal analysis and TEM. Studies has confirmed that soot particles shrink during their oxidation, as previously suspected. However, this shrinkage results in an overall change in structure. This structure becomes, on a radial basis, much more ordered near the edges, while the center itself becomes transparent to the TEM beam, implying a total lack of structure in this region. Although complex, this carbon structure is probably burning as to keep the density of the soot particles nearly the same. The TEM techniques developed for examination of soots has also been applied to Spherocarb. The Spherocarb during oxidation also increases its ordering. This ordering, by present theories, would imply that the reactivity would go. However, the reactivity goes up, implying that structure of carbon is secondary in importance to catalytic effects.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Fossil Energy, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91294
- OSTI ID:
- 589902
- Report Number(s):
- DOE/PC/91294-T19; ON: DE98052622; TRN: 98:001842
- Resource Relation:
- Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
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