INFRARED-SPECTROSCOPY OF THERMALLY TREATED LOW-RANK COALS .1. DIFFUSE-REFLECTANCE SPECTRA OF COALS HEATED TO 500-DEGREES IN AN INERT ATMOSPHERE

Diffuse reflectance infrared spectra of Western Canadian low-rank coal s that had been thermally treated in an inert (nitrogen) atmosphere sh ow that the rank of each coal was upgraded by the treatment. In partic ular, several features in the spectra imply an increase in aromaticity ; moreover, decarboxylation is evident after treatment at 500-degrees- C. Both results imply an increase in relative carbon content, and illu strate the suitability of infrared spectroscopy for the study of coal upgrading. Physical and chemical analyses of the treated coals tend to confirm the conclusions based on the spectra.