影响煤自燃气体产物释放的主要活性官能团

为了研究煤自燃发火气体产物与煤分子官能团之间的内在联系，进一步揭示煤自燃发火过程的微观变化特性，利用程序升温实验装置和原位红外光谱分析实验系统，得出了气体产物生成量和活性官能团含量之间的关联性。结果表明:CO、C₂H₄等指标气体浓度伴随温度升高显示为抛物线模式增长；活性官能团中，随着温度的不断升高，脂肪烃含量先持续增大，之后开始逐渐下降，C=C双键含量不断下降，含氧官能团含量先趋于稳定后逐渐增加。根据指标气体浓度变化，获得了高温反应过程中的5个特征温度点，进一步将其分为临界温度阶段、干裂–活性–增速温度阶段、增速–燃点温度阶段和燃烧阶段4个阶段，并对三个高温氧化阶段进行关联性分析发现:在临界温度阶段，影响CO、CO₂、CH₄和C₂H₆气体释放的主要活性官能团是羰基；在干裂–活性–增速温度阶段烷基链和桥键发生大量断裂，影响气体产物的主要活性官能团是脂肪烃和羰基；在增速–燃点温度阶段气体浓度与羰基和羧基等官能团呈负相关。得出干裂–活性–增速温度阶段是高温氧化过程中的危险阶段，需在该阶段前对氧化反应进行控制，以减少人员和物质损失。 

Key functional groups affecting the release of gaseous products during spontaneous combustion of coal

Coal–oxygen reaction theory, which is widely accepted, considers the reaction of coal and oxygen during combustion. In this research, the characteristics of spontaneous coal combustion were assessed at a high temperature to investigate the internal relationship between the gaseous products of this reaction and the functional groups in coal molecules and to further reveal the micro-characteristics of spontaneous coal combustion. Our self-developed temperature-programmed experimental system and in situ diffuse reflectance infrared Fourier transform spectroscopy were adopted to analyze the correlation between the contents of gaseous products and active functional groups. Results reveal that the contents of indicator gases, such as CO and C₂H₄, increase and show a parabolic curve. In terms of active functional groups, as temperature increases, the content of aliphatic hydrocarbons initially increases and then decreases gradually. The content of C=C groups decreases throughout this study, and the content of oxygen-containing functional groups gradually increases after equilibrium is reached. Five characteristic temperatures are obtained on the basis of the variation in gaseous products, and four oxidation stages are further divided. The relationship between active functional groups and gases during different temperature stages is determined. At the critical temperature stage, the main active functional group affecting the release of CO, CO₂, CH₄, and C₂H₆ is carbonyl. Numerous alkyl chains and bridge bonds are broken at the crack?active?speedup temperature stage, and the primary active functional groups influencing the gas products are aliphatic hydrocarbons and carbonyl groups. The concentration of gases at the speedup?ignition temperature stage is negatively correlated with carbonyl and carboxyl groups. Therefore, the crack?active?speedup temperature stage in high-temperature oxidation is dangerous, and oxidation should be controlled before this stage to reduce the loss of personnel and materials.