The macromolecular structure of low rank coals and lignites

Author

Susan E. Shawver

Date of Award

3-1986

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Jeffrey Kovac

Committee Members

John W. Larsen, Spiro Alexandratos

Abstract

The low rank coals, lignites and subbituminous coals, are considered to be three dimensionally covalently crosslinked macromolecules. The solvent swelling methodology used to characterize the macromolecular structure of bituminous coals is extended to the lower rank coals. The pyridine-extracted subbituminous coal obeyed the predictions of regular solution theory, while the pyridine-extracted lignites did not. The non-polar solubility parameter of the pyridine-extracted subbituminous coal was estimated 3 1/2 to be 9.5 (cal/cm³)^1/2. The 0-acetylated and 0-methylated subbituminous coals were assigned solubility parameters of 3 1/2 3 1/2 9.2(cal/cm³)^1/2. Solubility parameters of 9.2 and 9.1(cal/cm³)^1/2 were assigned to the two 0-acetylated lignite samples. Flory Interaction Parameters were calculated for a series of non-polar solvent-coal pairs. The Flory-Rehner and Kovac Equations were applied to the solvent swelling data to estimate crosslink densities and the number average molecular weight between crosslinks of the 0-acetylated lignites and pyridine-extracted subbituminous coal. The low rank coals contain hydrogen bonds which serve as crosslinks in the coal network. Solvent swelling experiments with non-polar solvents indicated the removal of ionic bonds was found to have little effect on the macromolecular structure of the lower rank coals.

Recommended Citation

Shawver, Susan E., "The macromolecular structure of low rank coals and lignites. " PhD diss., University of Tennessee, 1986.
https://trace.tennessee.edu/utk_graddiss/12471