煤自燃生成乙烯反应机理

Reaction mechanism of ethylene production during spontaneous combustion of coal

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.当温度达到120～170℃时,有乙烯生成.采用密度泛函B3LYP方法,在6-311G基组水平上研究了煤与氧发生自燃反应生成乙烯的反应体系,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.计算结果表明,煤分子氧化自燃生成乙烯的反应是氧分子攻击煤分子苯环侧链上的丙烯基团-C(25)H_2-C(26)H= C(27)H_2中间的C(25)原子,使苯环侧链上丙烯基团生成了带酸的基团(-CH_2-COOH)和乙烯.由反应活化能可知,生成乙烯的反应是一个自发式反应.

In the process of coal oxidized spontaneous combustion under different temperature the gaseous product was studied by the FFI spectroscope experiment. When the temperature rises to about 120 - 170℃, ethylene was produced. Using the B3LYP method, which studied the reaction system of the coal and the oxygen having the spontaneous combustion reaction and producing methane in the 6 - 311G base group level, 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 the reaction of coal molecule oxidized spontaneous combustion producing ethylene is the oxygen molecule attacks the C （ 25 ） atom in the middle of propylene group --C （ 25 ） H2-C （ 26 ） H = C （ 27 ） H2 on the coal molecule benzene ring side chain, which causes the propylene group on the benzene ring side chain to produce the acid group （--CH2--COOH） and the ethylene. The reaction of coal spontaneous combustion to produce ethylene is a spontaneous reaction judging by the reaction activation energy.