Study On Oxidation Characteristics Of Active Groups In Coal At Normal Temperature

Coal spontaneous combustion is a major disaster that is easy to happen in mines.The essence of its spontaneous combustion is active groups,while the number of them in lignite is relatively large.This article explores the features of the macro gas and micro groups during the oxidation of lignite at room temperature in two ways.Industrial element analysis,FTIR and XPS were used to construct the basic structural unit of lignite,and then the structure was optimized and frequency calculated.The results reveal the most active in the coal structure is the aliphatic carbon-carbon single bond connected to the benzene ring,and the most stable is the carbon-oxygen double in the carboxyl group and the carbonyl group.The main functional groups involved in the reaction are hydroxyl,aliphatic chains and carboxyl.According to the normal temperature oxidation experiment,the changes of macro gas and micro key active groups in the oxidation process of lignite were researched.The results reveal a higher content of CO₂ was generated during the reaction,and it is accompanied by obvious segmented features.Before 72h,CO₂ is mainly generated by the consumption of aliphatic hydrocarbons,hydroxyl groups and carboxyl groups;after 72h,CO₂ is mainly generated by the consumption of aliphatic hydrocarbons and hydroxyl groups.Carbon-oxygen complexes are important transition products.Quantum chemistry software was used to calculate the oxidation process of the key active groups in the oxidation reaction of lignite at room temperature,and the thermodynamic and kinetic parameters in the reaction process were analyzed.The results indicate the enthalpy changes and activation energy of different active groups are not the same.Both-CHOH group and-COOH group will produce CO₂ during the oxidation process at room temperature,and they are the key groups for CO₂produce.In summary,the oxidation law of lignite at room temperature is deeply explored,which offers a crucial theoretical basis for the prediction of early coal seams spontaneous combustion.Figure 28;Table 21;Reference 56...