A Study of the Products of Supercritical Fluid Extraction of Coals from the Chadan Deposit by Thermogravimetry and IR Spectroscopy

The thermal properties of the solid products of supercritical fluid extraction of coal from the Chadan deposit in benzene and the composition of bitumens separated in different temperature ranges (to 120, 120–200, 200–285, and 285–400°C) were studied. In contrast to the original coal, the thermal destruction of insoluble solid coal residue from extraction began at a higher temperature, and it was accompanied by a lower yield of volatiles. A comparative analysis of the characteristic parameters of the IR spectra and chromatograms showed changes in the composition of bitumen as a function of the extraction temperature: at low temperatures, oil components were extracted from coal, and the concentrations of tars and asphaltenes increased with temperature.