煤自燃生成甲烷的反应机理

Reaction mechanism of coal spontaneous combustion producing methane

应用傅里叶变换红外光谱仪实验研究了煤在氧化自燃过程中,不同温度下生成的气体产物,并采用密度泛函B3LYP方法,在6-311G水平上研究了煤与氧发生反应生成CH4的反应过程,对反应势能面上各驻点的几何构型进行了全优化,用频率分析方法和内禀反应坐标(IRC)方法对过渡态进行了验证.结果表明:温度升至120～170℃时,有CH4生成.煤氧化自燃生成CH4的反应是氧分子攻击苯环侧链上的丙基中间的碳原子,使苯环侧链上丙基生成带酸的基团(—CH2—COOH)和CH4.由反应活化能可知,生成CH4的反应是一个自发式反应.

The gaseous product in the process of coal oxidized spontaneous combustion under different temperature was studied by the FTI spectroscope experiment. Using the DFT B3LYP method, studied the reaction system of the coal and the oxygen having the spontaneous combustion reaction and producing methane under 6 - 311 G base group, and carried on optimization of all stagnation points geometry configuration on reaction potential energy surface, with the frequency analysis method and the IRC method carried on confirmation to the transient formation. The calculation results indicate that when the temperature rises to about 120 - 170 ℃, methane is produced, the reaction of coal oxidized spontaneous combustion producing methane is that the oxygen molecule attacks the carbon atom in the middle of propyl on the benzene ring side chain, which causes the propyl to produce the acid group （-CH2-COOH） and the methane. The reaction of producing CH4 is a spontaneous reaction judging by the reaction activation energy.