Analysis of Pyrolysis Performance and Molecular Structure of Five Kinds of Low-Rank Coals in Xinjiang Based on the TG-DTG Method

[Image: see text] Taking five coal samples (FCSs) in Xinjiang as the research object, characterizations such as proximate analysis, ultimate analysis, Fourier transform infrared (FTIR), and thermogravimetry-differential thermal analysis (TG-DTG) were carried out. The Coats–Redfern model was used to simulate pyrolysis kinetics of FCSs under different reaction orders (ROs). The results showed that except for HSBC, the R(2) of the other four coal samples are all higher than 0.9, which showed a good correlation effect. FCSs present similar reaction activation energy in the same RO and temperature range. Results of FTIR showed that the hydroxyl groups of FCSs, in the range of 3100–3600 cm(–1), were mainly self-associated hydroxyl hydrogen bonds and hydroxyl π bonds, and they occupied over 63%. Among them, the pyrolysis characteristic index (D) of XBC was 4.139 × 10(–6), higher than those of other samples, and it showed good pyrolysis performance. Moreover, by reducing the temperature range appropriately, the fitting results showed a better correlation effect.