Small-angle x-ray scattering studies of the porosity of coals and chars. Final technical report, Sept. 30, 1978-March 31, 1981
Small-angle x-ray scattering measurements are reported for 15 coal samples in the PSOC series of coals. The rank of the coal was found to be the main factor determining the form of the small-angle scattering curves. Analysis of the scattering curves provides evidence for the presence of three classes of pores--(1) large pores, with dimensions of at least 300 A, (2) intermediate sized pores, with average dimensions of the order of 100 or 200 A, and (3) very small pores, which with dimensions no greater than about 30 A. These three types of pores are referred to as macropores, transition pores, and micropores, respectively. The system of three kinds of pores suggested by the x-ray scattering data is in good agreement with the three-class pore structure developed by other workers' investigations employing techniques besides small-angle x-ray scattering. The specific surfaces of the coals were calculated from the scattering curves. A method was developed for estimating the fractions of the total specific surface which should be assigned to the macropores and transition pores under the assumption that the specific surface computed from the scattering curves did not include any contribution from the micropores. The specific surfaces calculated from the scattering data have been compared with the specific surfaces obtained by adsorption of nitrogen at low temperatures and by carbon dioxide at room temperature. The x-ray data are not consistent with the suggestion that many pores have dimensions of some hundreds of Angstroms but have restricted openings which exclude nitrogen at low temperatures. Instead, the high values of surface area obtained by carbon dioxide adsorptiom must be the result of the contribution of a large number of pores with minimum pore dimensions which are not greater than about 30 A. 2 figures, 1 table.
- Research Organization:
- Missouri Univ., Columbia (USA). Dept. of Physics
- DOE Contract Number:
- AC22-77ET11426
- OSTI ID:
- 6440785
- Report Number(s):
- DOE/ET/11426-T2; ON: DE83007040
- Resource Relation:
- Other Information: Microfiche only, copy does not permit paper copy reproduction
- Country of Publication:
- United States
- Language:
- English
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CARBON DIOXIDE
ADSORPTION
COAL
POROSITY
SORPTIVE PROPERTIES
SURFACE AREA
NITROGEN
COAL RANK
CORRELATIONS
EXPERIMENTAL DATA
SMALL ANGLE SCATTERING
X-RAY DIFFRACTION
CARBON COMPOUNDS
CARBON OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
COHERENT SCATTERING
DATA
DIFFRACTION
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
INFORMATION
MATERIALS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SORPTION
SURFACE PROPERTIES
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