Study on the Coal-Oxygen Intrinsic Reaction at Low Temperature by the Subtraction Method

Coal oxidation involves complex physical and chemical processes as well as many reaction pathways. The subtraction method was used to investigate the law of the coal-oxygen intrinsic reaction at low temperatures. The subtraction method is to subtract the characteristic curve of the coal reaction in N₂ from the characteristic curve of coal oxidation in air, which can remove the influence of pyrolysis reaction, water evaporation, and gas desorption on coal low-temperature oxidation, and ultimately obtain the coal-oxygen intrinsic reaction curve under the pure oxidation pathway. To reveal the internal relationship of the coal-oxygen intrinsic reaction between the release of gas products and the conversion of active functional groups, a temperature-programmed system was used to analyze the law of index gas products. Furthermore, Fourier infrared spectroscopy was used to analyze the conversion of active functional groups in the low-temperature reaction process of coal. The findings revealed that the coal-oxygen intrinsic reaction obtained through subtraction played a significant role in the release of gas and the conversion of aliphatic hydrocarbons in the overall process of the coal low-temperature reaction. However, the alterations in the N₂ atmosphere were relatively weak. The gas release of CO and CO₂ gradually increased with increasing temperature, as did the concentration of oxygen-containing functional groups, and there was a positive correlation between them.