煤自燃初期的反应机理研究

从实验得到的可能引起煤自燃的8个活性基团入手，提出了一系列简单煤分子模型，利用密度泛函DFT/6-31G对其完成了几何优化，计算了包括反应焓变、吉布斯自由能和活化能等，从热力学和动力学角度分析了计算结果。基于理论计算获得了煤活性基团的活泼性次序，得出了煤自燃初期的反应机理主要是氧分子先进攻煤分子中的活性基团，产生活泼性很高的中间体，然后中间体进一步反应得到水或二氧化碳及其他反应产物，计算结果与实验基本符合。

Mechanism of spontaneous combustion of coal at initial stage

Based on 8 active groups leading to spontaneous combustion of coal, a simple model of coal was developed to investigate the reaction mechanism of spontaneous combustion of coals at initial stage. Calculations about coal molecules model were carried out with Gaussian 03 (DFT-B3LYP) program. The results show that the oxidation reactions of 1, 3, 5, 6, 7, and 8 are exothermic, and except for reaction 2 and 4, other reactions have negative ΔGθ, which means that these reactions are spontaneous at room temperature. According to the calculations of activation energies of the reactions, it is concluded that six among the eight reactants tend to react with oxygen spontaneously at room temperature. Furthermore, the order of activity of these active groups deduced during experiments is roughly confirmed by the theoretical calculations. The reaction mechanism of low-temperature oxidation of coal at initial stage is also presented. The results well agree with those obtained by previous experiments.