Investigation of the oxidation behavior of a Turkey coal at low temperature by TGA, FTIR and BET analysis

The mechanism and kinetics of the Tavşanlı (Turkey)-coal oxidation at low-temperature before ignition was investigated in this study. FTIR, BET analysis were used to determine the changes in the structure of coal at this temperature range. The gas products released during oxidation was monitored by TG-FTIR apparatus at a heating rate of 5°C min−1. The kinetics parameters of the oxidation process at the low-temperature were determined by thermal analysis apparatus. TG data taken in air atmosphere at heating rates of 1°C, 2.5°C, 5°C, and 10°C min−1 were plotted at non-isothermal heating program. For the kinetics analysis, the low-temperature oxidation region was divided into two regions, corresponding temperature ranges of which were 25–150°C and 150 ~ 250°C, respectively. It was seen that the mass-gain in coal between 150°C~250°C was due to the accumulation of -C = O functional groups in the coal structure. It was observed that the mass-loss region at 25–150°C is best described by F2: [(1-α)−1–1] model and the mass-gain region at 150 ~ 250°C is R3: [1-(1-α)1/3] model. The activation energies, pre-exponential factors of the regions were calculated by using Ortega method. It was found 49.9 and 74.5 kJmol−1, respectively.