Chemical Structure and Properties of Heat Treated Coal in the Early State of Carbonization (XXIV)

Abstract

As part of a serial research work for coal structure, the IR spectra of the pyridine extracts of 16 different ranks of coal were measured by KBr method; from which some information in comparison with that of the original coals were obtained as follows.(1) Absorptions concerned with OH groupsThe absorption coefficients both of 3, 450 and 1, 260 cm-1, bands of the extract de-creased linearly, like that of the original coal, with the increase of the carbon content of the original coal.(2) Absorptions concerned with aliphatic CH hydrogensTwo peaks appeared at Taiheiya and Yubari, similar to the case of the original coal, on the plot of the absorption coefficient of 2, 920cm-1 band of the extract versus carbon content of the original coal, but rather higher coefficients were found in the extracts of lower-rank coals than in those original coal themselves. The absorption coefficient of 1, 450cm-1 band of the extract decreased as the carbon content of the original coal increased. While the absorption coefficient of 1, 380cm-1 band for the original coal had only one peak at Yubari, two peaks at Taiheiya and Yubari were found for that of the extract.(3) Absorptions concerned with Aromatic CH hydrogensIn stead of Bibai from which appeared the absorption at 3, 030cm-1 in case of the origi-nal coal, the band arose in the extract of a lower-rank coal, Takamatsu. In general, the absorption coefficient of 3, 030cm-1 band of the extract increased with increasing carbon content of the original coal except at Itmann, and had somewhat larger value than that of the corresponding coal. The absorption coefficients of 870, 820 and 750 cm-1 bands had quite similar trends with what were found in the original coal, though partial difference in the absorption coefficient of 750cm-1 band was noted.(4) The absorption band at 1, 600cm-1Whereas a lower coefficient compared with that of the original coal was seen for some lower rank coal extracts, no significant difference was found between the extract and the original coal for higher rank coals.The conclusion drawn from IR spectra observation was that the extracts obtained from the coals lower in rank than Bibai were richer in aliphatic structures and that the extratcs from higher rank coals had structures quite similar to their original coals. The deviation shown by Itmann coal extract was ascribed to the behavior of resinous material which might be extracted more from this sort of coal than to the behavior of the coal itself.