Evolved gas analysis at thermal treatment of some solid fossil fuels

Coupled TG-FTIR technique was used for identification of gaseous compounds evolved at thermal treatment of six coal samples from different deposits (Bulgaria, Russia, Ukraine). The experiments were carried out under dynamic heating conditions up to 900°C at heating rates of 5, 10 or 50 K min^–1 in a stream of dry air. The emission of CO₂, H₂O, CO, SO₂, COS, methane, methanol, formic acid, formaldehyde, acetaldehyde, chlorobenzene was clearly identified in FTIR spectra of the samples studied. The formation of ethanol, ethane, ethylene and p-xylene, at least on the level of traces, was also identified. At the heating rate of 5°C min^–1 the temperature of maximum intensities of the characteristic peaks of COS was 270°C, of formaldehyde, formic acid, ethane and methanol 330°C, of SO₂, CO, acetic acid, ethylene and p-xylene 400°C and of chlorobenzene 500°C. At 10°C min^–1 and 50°C min^–1 these temperatures were shifted, respectively, by 70–300°C and 150–450°C towards higher temperatures and the respective absorption bands in FTIR spectra were, as a rule, more intensive.