含氧中间产物变化规律及其在煤低温氧化过程中的作用

Variation of oxygen-containing intermediates and its role in low-temperature oxidation of coal

煤中活性基团与氧反应生成含氧中间产物对煤自燃过程具有重要影响,然而,由于其处于中间态,难以直接获得含氧中间产物的变化规律,导致含氧中间产物在煤自燃过程中的作用不清晰。为此,提出了一种利用煤中活性基团在不同气氛下的活性差值来测试含氧中间产物的方法,并在这种方法的指导下,分别利用综合热重分析仪和原位红外对含氧中间产物的产生规律进行了研究。结果表明,煤中参与初始氧化反应的基团主要是亚甲基,亚甲基与氧气先生成过氧化物后在一段温度范围内累积,当温度大于80℃之后开始逐渐分解产生气体和其他类型的含氧中间产物。煤化程度越低的煤生成的含氧中间产物越不稳定,容易进行下一步反应并释放大量热量,含氧中间产物的稳定性决定了煤氧化发展进程,尤其是在煤低温氧化过程中起到了承上启下的关键作用,因此可以通过替代氧化破坏煤中活性基团或提高含氧中间产物的稳定性来实现防治煤炭自燃的目的。

The formation of oxygen-containing intermediates by the reaction of active groups with oxygen in coal has an important impact on the process of coal spontaneous combustion.However,the oxygen-containing intermediates are in the intermediate state,it is difficult to directly obtain the change law of oxygen-containing intermediates,resulting in the unclear role of oxygen-containing intermediates in the process of coal spontaneous combustion.Therefore,a method for testing oxygen-containing intermediates by using the activity difference of active groups in coal under different atmospheres was proposed.Since coal mainly produces water evaporation and cracking under a nitrogen atmosphere while mainly produces oxygen-containing intermediates,gas,water evaporation and cracking under an air atmosphere,the variation law of intermediate products can be obtained indirectly by using the difference between the two atmospheres based on the developed method.Under the guidance of this method,the production law of oxygen-containing intermediates was studied by a comprehensive thermogravimetric analyzer and in-situ infrared.The experimental results show that the groups involved in the initial oxidation reaction in coal are mainly methylene.After methylene forms peroxide with oxygen,it accumulates in a temperature range.When the temperature is greater than 80℃,it begins to decompose gradually to produce gas and other types of oxygen-containing intermediates.Oxygenated intermediates play a key role in the process of coal spontaneous combustion.When the oxygenated intermediates are unstable,it is easy to carry out the next reaction and release a large amount of heat,resulting in easier coal spontaneous combustion.When the oxygen-containing intermediate products are relatively stable,the next reaction is more difficult to occur,and the generated heat is relatively small,resulting in difficulty for spontaneous combustion of coal.Therefore,preventing coal spontaneous combustion can be achieved by reducing the activity of active groups in coal or improving the stability of oxygenated intermediates.