Experimental research on elemental migration rule and in-situ FTIR during sub-bituminous coal low-temperature oxidation

Based on Kinetics and thermodynamics theory,the migration rules of five basic elements including C,H,O, N and S were studied,and the variation trend of main functional groups was also analyzed during the coal heating process. The results show that variation of carbon oxide compounds played a leading role in the physical and chemical adsorption phase,while the variation frequency of hydrocarbons and nitrogen compounds exceeded carbon oxide com- pounds. The apparent activation energy value of H element was the smallest and the energy value of O and S element were negative. The migration process of C,H and N was an endothermic process respectively and that of O and S was an exothermic process. Aliphatic C—H in the coal was gradually decreased when coal was heated. The contents of COOH and C O had same variation trend,and it was obviously that the contents of both groups increased gradually over 120 ℃ . Besides,the chemical reaction steps involved in coal low-temperature oxidation were also studied.