Molecular accessibility in solvent swelled coal
The EPR-spin probe method was used to study the swelling of covalently cross-linked 2%, 4%, 6%, 8% and 12% polystyrene-divinyl benzene copolymers, used as models of APCS coal structural elements. The results were compared with swelling studies on APCS coals and confirmed results showing that coal was polymeric, that it had covalent cross-links increasing with rank, that it was structurally anisotropic, and that its swelling was anisotropic. The low temperature swelling of Argonne Premium Coal Samples using solvents of varying polarity was investigated. The variation in the shape of the pore was followed as a function of temperature and swelling solvent polarity. This change in pore structure was attributed to break-up of the hydrogen bonding network in coal by polar solvents. The modification in pore shape from spherical to cylindrical was attributed to anisotropy in hydrogen bond densities. The structural changes in coal pores that occur when APCS coal is dehydrated prior to swelling with polar solvents has been determined. These changes are different from those that occur in the absence of prior dehydration. Most impressive is the huge change that occurs in lignite coal (Beulah-Zap). It appears that this coal has collapsed upon dehydration preventing any spin probe from being trapped in the dehydrated lignite upon swelling. Various sized probes have been studied. A study on the variation in the hydrogen bonding character of the pore wall as the coals are swelled with various polar solvents has also been completed. A statistical analysis of the data has been completed to determine important trends in the data. 9 refs.
- Research Organization:
- Alabama Univ., University, AL (United States). Dept. of Chemistry
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-90PC90284
- OSTI ID:
- 5915889
- Report Number(s):
- DOE/PC/90284-5; ON: DE92004517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
010600* -- Coal
Lignite
& Peat-- Properties & Composition
AZINES
BITUMINOUS COAL
BLACK COAL
BROWN COAL
CARBONACEOUS MATERIALS
COAL
COAL RANK
CRYSTAL STRUCTURE
DOCUMENT TYPES
ELECTRON SPIN RESONANCE
ENERGY SOURCES
FOSSIL FUELS
FUELS
HETEROCYCLIC COMPOUNDS
ION EXCHANGE MATERIALS
LIGNITE
MAGNETIC RESONANCE
MATERIALS
MICROSTRUCTURE
NITRO COMPOUNDS
NITROBENZENE
ORGANIC COMPOUNDS
ORGANIC ION EXCHANGERS
ORGANIC NITROGEN COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYOLEFINS
POLYSTYRENE-DVB
POROSITY
PROGRESS REPORT
PYRIDINE
PYRIDINES
RESONANCE
SOLVENTS
SWELLING
TEMPERATURE DEPENDENCE