{sup 1}H NMR spectroscopy and spin-lattice relaxation of Argonne Premium coals

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:441410

Hayamizu, Kikuko; Hayashi, Shigenobu; Kamiya, Kunio; Kawamura, Mitsutaka ^[1]

---

1. National Chemical Laboratory, Tsukuba, Ibaraki (Japan)

Solid-state {sup 1}H NMR spectra and spin-lattice relaxation times (T{sub 1}) are reported for eight Argonne Premium coals that were prepared under several different conditions. Measurements were performed on pristine coals, degassed and dried samples, dried coal samples stored in capped vials for about 1 year, and coals treated with two different acids, HCl and HF-HCl. In general, nonexponential relaxation curves were analyzed by fitting the data to two exponential decay constants. With acid treatment, an increase in T{sub 1} was observed for the coals with carbon contents of less than 77% and a decrease was observed for the higher rank coals. Electron spin resonance (ESR) measurements were performed on coals with and without acid treatment to assess the {sub 1}H spin-lattice relaxation mechanisms. The important {sup 1}H NMR relaxation mechanism in lignite and subbituminous coals is due to the presence of paramagnetic metal ions, whereas that in bituminous coals is due to organic free radicals. The effects of various treatment on the {sup 1}H NMR spectra and the T{sub 1} values of coals are discussed. 14 refs., 11 figs.

• OSTI ID: 441410
• Report Number(s): CONF-891206--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
40 CHEMISTRY
CARBON
COAL
DATA ANALYSIS
DECAY
ELECTRON SPIN RESONANCE
LIGNITE
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
SPECTROSCOPY
SPIN-LATTICE RELAXATION