Zhang Xun, Yu Chen, Gao Fei, Lu Bing, Zou Jiahui
College of Mining Engineering, Liaoning Technical University, Fuxin, Liaoning123000, China.
College of Safety Science & Engineering, Liaoning Technical University, Fuxin, Liaoning123000, China.
ACS Omega. 2023 Jan 9;8(3):3396-3403. doi: 10.1021/acsomega.2c07273. eCollection 2023 Jan 24.
In this paper, in order to further reveal the mechanism of oxidation inhibitors inhibiting coal spontaneous combustion, the mechanism of typical antioxidants butylated hydroxytoluene (BHT) and vitamin C (VC) inhibiting coal low-temperature oxidation was studied by thermogravimetry (TG), Fourier transform infrared spectroscopy, and quantum chemical simulation. This paper studies the thermal reaction process of coal by TG. The experimental results showed that the characteristic temperature of coal samples increased significantly after adding an antioxidant, and the maximum exothermic peak temperature of coal samples with BHT was 36 °C higher than that of raw coal, and the dehydration activation energy was 1.22 times higher than that of raw coal. Then, through the Fourier transform infrared spectroscopy experiment, it is concluded that antioxidants have a great influence on the content of active groups in the process of oxidative heating of coal, and the hydroxyl structure changes in coal are the most obvious. After BHT and VC were added to the coal, the hydroxyl content in the coal was reduced by 5.90 and 4.20%, respectively. Finally, the molecular models of antioxidants and oxygen-containing functional groups (RCOOH, R-CHO, and R-CH-CH-OH) in coal are constructed using quantum chemical theory, and their frontier orbitals and thermodynamic data are calculated according to density functional theory. The reaction mechanisms of antioxidants reacting with hydroxyl groups and with hydroxyl groups and oxygen-containing functional groups were comparatively analyzed. The results of orbital gap analysis indicated that antioxidants react more easily with hydroxyl groups than with oxygen-containing functional groups, and the order of their reaction activity is BHT > VC > R-CH-CH-OH > R-CHO > RCOOH. Compared to reactions containing oxygen-containing functional groups and hydroxyl groups, the thermodynamic reaction of hydroxyl groups and antioxidants is more active. Because antioxidants preferentially react with hydroxyl radicals and inhibit part of the chain cycle reaction during spontaneous combustion of coal, antioxidants play a good inhibitory role in spontaneous combustion of coal.
本文为进一步揭示氧化抑制剂抑制煤炭自燃的机理，采用热重分析法（TG）、傅里叶变换红外光谱法以及量子化学模拟研究了典型抗氧化剂2,6-二叔丁基对甲酚（BHT）和维生素C（VC）抑制煤炭低温氧化的机理。本文通过TG研究了煤的热反应过程。实验结果表明，添加抗氧化剂后煤样的特征温度显著升高，添加BHT的煤样最大放热峰温度比原煤高36℃，脱水活化能是原煤的1.22倍。然后，通过傅里叶变换红外光谱实验得出，抗氧化剂对煤氧化加热过程中活性基团的含量有很大影响，其中煤中羟基结构变化最为明显。在煤中添加BHT和VC后，煤中羟基含量分别降低了5.90%和4.20%。最后，利用量子化学理论构建了抗氧化剂与煤中含氧官能团（RCOOH、R-CHO和R-CH-CH-OH）的分子模型，并根据密度泛函理论计算了它们的前线轨道和热力学数据。对比分析了抗氧化剂与羟基以及与羟基和含氧官能团反应的机理。轨道能隙分析结果表明，抗氧化剂与羟基的反应比与含氧官能团的反应更容易发生，其反应活性顺序为BHT＞VC＞R-CH-CH-OH＞R-CHO＞RCOOH。与含有含氧官能团和羟基的反应相比，羟基与抗氧化剂的热力学反应更活跃。由于抗氧化剂优先与羟基自由基反应，抑制了煤炭自燃过程中的部分链循环反应，因此抗氧化剂对煤炭自燃具有良好的抑制作用。
