A study of coal extraction with electron paramagnetic resonance (EPR) and proton nuclear magnetic resonance relaxation techniques. Quarterly technical progress report, April 1, 1993--June 30, 1993
- State Univ. of New York, Binghamton, NY (United States). Dept. of Chemistry
- Tohoku Univ., Sendai (Japan). Inst. for Chemical Reaction science
An electron spin and proton magnetic relaxation study is presented on the effects of the solvent extraction of coal on the macromoleculer network of the coal and on the mobile molecular species that are initially within the coal. The eight Argonne Premium coals were extracted at room temperature with a 1:1 (v/v) N-methylpyrrolidinone (NMP)-CS2 solvent mixture under an inert atmosphere. As much solvent as possible was removed from extract and residue by treatment in a vacuum. The mobilization of molecular free radicals by the solvent and the exposure of free radicals in the macromoleculer matrix to solvent or to species dissolved in the solvent, results in a preferential survival of residue radicals of types that depend on the particular coal and results in the apparently fairly uniform loss of all types of radicals in bituminous coal extracts. The surviving extract and residue free radicals are more predominantly of the odd- alternate hydrocarbon free radical type. The spin-lattice relaxation (SLR) of these coal free radicals has previously been inferred (Doetschman and Dwyer, Energy Fuels, 1992, 6, 783) to be from the modulation of the intramolecular electron-nuclear dipole-interactions of the CH groups in a magnetic field by rocldng motions of the radical in the coal matrix. Such a modulation would depend not only on the rocking amplitude and frequency but also upon the electron spin density at the CH groups in the radical. The observed SLR rates decrease with coal rank in agreement with the smaller spin densities and the lower rocidng amplitudes that are expected for the larger polycondensed ring systems in coals of higher rank. The SLR rates are found to be generally faster in the extracts (than residues) where the molecular species would be expected to have a smaller polycondensed ring system than in the macromoleculer matrix of the residue.
- Research Organization:
- State Univ. of New York, Binghamton, NY (United States). Dept. of Chemistry
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91299
- OSTI ID:
- 10180889
- Report Number(s):
- DOE/PC/91299-11; ON: DE93041295
- Resource Relation:
- Other Information: PBD: [1993]
- Country of Publication:
- United States
- Language:
- English
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