1991 Volume 70 Issue 8 Pages 802-810
Coal structure is reviewed based on the results from solvent extrac-tions of coals, especially on those with Carbon disulfide-N-Methyl-2-pyrrolidinone mixed solvent extraction. It has been widely suggested that coals consist of covalently three-dimensional macromolecular networks and a small amount of relatively low molecu-lar-weight molecules. However, recently, several results which can not be explained by the above concept, have been reported. First, the very high extraction yields obtained for some bituminous coals suggest that a considerable amount of solvent soluble molecules exist ori-ginally in coals. Next, there are many evidences which indicate that noncovalent inter-molecular interactions such as hydrogen bondings, aromatic-aromatic, charge transfer, and dipole-dipole interactions play important roles for the formation of coal macromolecular structures. It is suggested that coals seem to be comprised of “aggregate” of coal molecules having a continuous molecular weight distribution.
