煤中水分作用于煤自燃反应过程的原子尺度表征

Atomic scale characterization of the reaction mechanism of moisture in coal acting on coal spontaneous combustion process

为了探讨煤中水分作用于煤自燃过程的反应机制,创新性地引入同位素标记方法,利用元素示踪原理探讨水分子中各元素的迁移转化规律。将实验煤样用3种同位素水(蒸馏水、D_(2)O、H_(2)^(18)O)进行浸泡、干燥、浸泡等一系列过程处理,得到同位素标记的不同形态水分煤样。通过程序升温氧化实验模拟煤自燃反应过程,利用气相色谱仪测定气体产物体积,同时借助于在线质谱仪测定同位素原子参与生成各类气体的离子流强度,研究水分子中H、O原子作用于气体生成的迁移规律和生成机制。在煤自燃气相产物中检测到了C^(18)O_(2)、C^(18)O和CH_(3)D等同位素气体,说明水分子中H、O原子可以直接参与煤自燃反应过程。煤中不同形态水分在煤自燃反应不同阶段发挥作用:外在水分在煤自燃反应缓慢氧化阶段初期开始参与反应,在快速氧化阶段后期作用减弱;内在水分在煤自燃反应的加速氧化阶段与快速氧化阶段参与反应,在140℃左右作用效果最强。水分子中H与O原子在煤自燃反应过程中参与方式不同,H原子会与煤分子中甲基类自由基反应生成CH_(3)D,而O原子可以参与到含羰基类化合物的生成。

In order to investigate the reaction mechanism of moisture in coal acting on coal spontaneous combustion process,the isotope labeling method was innovatively introduced and the migration and transformation rule of each element in H_(2)O was discussed by using the principle of element tracer.The experimental coal samples were soaked,dried and soaked with three kinds of isotopic moisture(distilled water,D_(2)O and H_(2)^(18)O)to obtain different forms of isotope-labeled moisture coal samples.The process of coal spontaneous combustion was simulated by temperature-programmed oxidation experiment,and the volume of gas product was measured by gas chromatography.Meanwhile,the ion current intensity of isotope atoms participating in the generation of various gases was measured by online mass spectrometer,and the migration rule and formation mechanism of hydrogen and oxygen atoms acting on gas formation in H_(2)O were studied.Isotopic gases such as C^(18)O_(2),C^(18)O,and CH_(3)D were detected in the gas products of coal spontaneous combustion,which indicates that H and O atoms in H_(2)O can directly participate in the reaction of coal spontaneous combustion.Different forms of moisture in coal play a role in different stages of coal spontaneous combustion reaction:external moisture begin to participate in the reaction at the start of the slow oxidation stage of coal spontaneous combustion reaction,and weaken in the later stage of rapid oxidation.The intrinsic moisture participate in the accelerated oxidation stage and the rapid oxidation stage,and the effect is the strongest at around 140℃.H atom and O atom in H 2O have different pathways of taking part in the chemical reaction of coal oxygen.H atoms react with methyl radicals in coal molecules to generate CH 3D,while O atoms can participate in the generation of various carbonyl-containing compounds.