【作者】 唐一博；

【导师】 李增华；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2014， 博士

【摘要】 煤自燃是煤炭工业中普遍存在的一种严重灾害，研究煤自燃的特性和机理对防治灾害降低损失具有重要的意义。煤的低温氧化是煤自燃发展过程中的一个重要阶段，是影响煤炭自燃发生和发展的关键阶段。而煤是一种由相似但不相同分子结构构成的复杂有机矿物燃料，其结构异常复杂，并含有多种易氧化的活性基团。直接研究其中某种活性基团氧化过程中的结构变化往往达不到预期的效果。因此，可采用模型化合物，将复杂大分子体系分解为简单小分子结构，从而研究复杂煤分子中表面活性基团的低温氧化特性。根据煤化学和煤的大分子模型理论，煤氧复合过程中，煤分子中的含氧官能团、侧链和桥键等活性基团易被氧化，即煤氧化自热效应的导因，而煤中芳香环的化学性质相对稳定，较难参与氧化反应，且苯环数目对活性基团的特性影响不大。因此，本文选择用芳环与某些煤中代表性的活性基团组成煤自燃模型化合物：苯乙醚、苯乙醛、苯丙醇、苯甲酸、二苯基甲烷、二苯基硫醚进行模拟实验研究。对6种模型化合物进行“气-液”和“气-固”反应条件下的程序升温氧化实验。通过对不同温度下的各类氧化产物进行气相色谱、红外光谱以及色谱-质谱联用分析。发现模型化合物的低温氧化与煤的低温氧化类似，其氧化过程中存在临界温度，即温度超过一定值时，模型化合物的氧化活性会迅速增强；模型化合物的低温氧化是一个多步的复杂反应，包含对氧气的化学吸附和中间产物生成这一过程。通过对模型化合物氧化产物的定性分析发现其主要成分包含CO、CO2、苯、苯酚及其它各类氧化的中间产物或副产物，也与煤自燃产物相一致。在此基础上，对各模型化合物氧化反应历程进行了分析。通过模型化合物的耗氧特性，分析了模型化合物氧化过程中的活化能及指前因子等氧化动力学参数；结果表明，6种模型化合物中苯乙醛（—CHO）和二苯基甲烷（—CH2—）的活化能较小，氧化活性较强。但因醛基—CHO在煤中的含量较低，故煤中的亚甲基桥键—CH2—对煤的自燃特性具有重要影响。通过TG/DTA技术研究了模型化合物在低温氧化过程中的放热特性，发现煤自燃模型化合物在低温氧化最初阶段有微幅的增重，随着温度的进一步升高进而迅速失重，并最终维持稳定。相比之下，模型化合物的DTA曲线在整个低温氧化过程中存在不止一个吸/放热峰，表明模型化合物的中活性结构的在不同温度阶段有复杂的热变化。通过对煤中活性官能团氧化特性的分析，选取植酸、2,6-二叔丁基对甲酚、没食子酸正丙酯等五种抗氧化剂进行模型化合物的低温氧化抑制实验，并应用于煤样自燃抑制实验。结果表明，2,6-二叔丁基对甲酚和植酸在160℃之后对煤的氧化有良好的抑制效果。同时，通过各抗氧化剂对煤自燃阻化实验结果分析其氧化抑制机理。更多还原

【Abstract】 Spontaneous combustion of coal (SCC) is a serious hazard in the the coalindustry. The study on characteristics and mechanism of spontaneous combustion ofcoal has a critical significance for the preventing and reducing losses on this disaster.Low-temperature oxidation is an important stage for coal spontaneous combustion,which controls the occurrence and development of spontaneous combustion. As aresult, the research targeting at low-temperature oxidation of coal plays a key role inprevention of self-heating hazards. It’s well known that coal is a complexorganic-fossil-fuel which constituted by similar but different molecular structures.Generally, the coal is considered as the porous polymer with large internal surfacearea. Given this property, direct investigation into the internal structural changes ofcoal during the low-temperature oxidation period is often difficult to succeed.According to theories on Coal Chemistry, in the combining process of oxygenand coal, O-containing functional groups, such as side-chains and bridging bonds aresusceptible to be oxidized, while the chemical properties of aromatic rings arerelatively stable. As a consequence, the model compounds which contained a benzenering and a representative group of coal were used in this paper for studyingspontaneous combustion properties of coal. In order to simplify the complexity ofbiological macromolecules into small molecules of simple structure and study theiroxidation performance, the model compounds: phenetole, phenylacetaldehyde,phenylpropanol, benzoic acid, diphenylmethane and diphenylsulfide are adopted asthe substitute material for simulating the oxidation properties of active groups in coal.The programmed-heating experiments of six kinds of model compounds werecarried out. The results show that the phenylacetaldehyde and diphenyl methane havehigher oxidative activity than others. In the light of data on GC, FTIR and GC/MS,the outcome shows that there is a critical temperature in low-temperature oxidation ofmodel compounds. The oxidative activity of model compounds will sharply increaseonce the temperature over a certain value. Besides, there is a time delay between themaximum O2consumption and the generation of oxidation products, which alsoindicate that, like self-ignite of coal, the oxidation of model compounds is acomplicated reaction with multiple steps. The oxidation products of modelcompounds contain CO, CO2, benzene, phenol and other intermediate products. Thereaction pathways of model compounds were inferred on the basis of the compositionof oxidation products. Oxidation kinetics such as activation energy and pre-exponential factor wereanalyzed, according to the O2consumption rate of model compounds. In addition,their thermal characteristics were analyzed by the TG/DTA. Similar with the coal, theweight of model compounds will slightly increase at initial period. Then the TG curveappears a significant decrease with the temperature rising continuously, and finallykeep stable. It is worth noting that more than one peak were shown in the DTA curveduring the low-temperature process, which suggested that the oxidation of modelcompounds has complicated thermal-variation in different temperature stage.On the basis of oxidation properties of active groups in coal, five differentantioxidants (BHT, propyl gallate, phytic, sodium benzoate and ascorbic acid) wereemployed for inhibiting the low-temperature oxidation of model compounds, and alsoapplied to the coal samples. The outcomes indicate that the BHT and phytic have welleffect on the inhibition of coal oxidation. Further, the inhibition mechanism ofantioxidants was analyzed.更多还原