Pyridine extractable material from bituminous coal, its donor properties and its effect on plastic properties

Abstract

A Japanese bituminous coal (81.2%C) was extracted with pyridine at 200–400 °C to give an extraction yield of 50 wt% at 400 °C. However, after quinoline extraction the same level of pyridine extraction (50 wt% yield) could be obtained at 300 °C. This result was interpreted as being due to the intimate occlusion of extractable material in the network macromolecular structure or in the larger molecules. Room temperature pyridine extraction of methylated coal and the repeated pyridine extraction at 200 °C reinforced this view Pyridine extracts at room temperature, 300 °C and 400 °C contained similar compounds. This was also taken as confirmation that the pyridine extracts are not thermal decomposition products, but the true extracts. Pyridine extraction residues obtained at room temperature, 200 °C and 400 °C, and the original coal were treated in naphthalene at 400 °C for 15 min and then extracted by pyridine. A total extraction yield of 50 wt% was obtained for all treatments, clearly indicating that the pyridine extract had no donor property. The implication of these results to the plastic phenomena of coal during heating is discussed.