Transition of the oxygen-containing functional groups of low rank coal during drying process

The variations in the main functional groups of two different low rank coals during drying process were in- vestigated using Fourier-transform infrared spectrometer based on the curve-infrared analysis. The results show that the main functional groups of the coals decrease first and then increase with the increase of temperature during the low and high temperature drying process. When above 190 ℃ in the low temperature drying process and above 600 ℃ in the high temperature drying process,the main functional groups of the coals are seriously oxidized. Methylene contained in the aliphatic hydrocarbon structures of the low rank coal is very apt to be oxidized during the drying process. The high- er the oxygen content in drying agent,the more highly oxidized the coal during the simulated flue gas drying process. The low rank coal dried under 600 ℃ has the weakness of spontaneous combustion tendency and re-absorption feature during the high temperature flue gas drying process. Meanwhile,the aromatic hydrocarbon of the coal molecular struc- tures can be oxidized by the oxygen of drying agent.