Kinetic study for the production mechanism of halo-dibenzo-p-dioxin

为了确定燃烧中二苯并对二恶英的生成通道为2C_6H_5O→C_6H_4O_2C_6H_4+2H，用激波管法研究了苯氧基(C_6H_5O)在1250K-1700K温度范围内的高温反应。用甲氧基苯(C6H5OCH3)和三氟甲氧基苯(C6H5OCF3)作为C6H5O自由基的来源。通过将实验结果与计算机模拟结果进行比较，讨论了包括二苯并对二恶英生成通道在内的C6H5O自由基的高温反应。用Ar混合物稀释C6H5OCH3和C6H5OCF3的反射激波后的最终产物，用气相色谱分析了C6H5O分解的反应产物。我们发现，冲击的背后不仅产生了直链碳氢化合物，还产生了苯酚等芳香族化合物。然而，在用Ar混合气体稀释的C_6H_5OCH_3和C_6H_5OCF3激波后，没有检测到二苯并对二恶英作为最终产物。为了模拟二苯并对二恶英的产率与温度的关系，建立了二苯并对二恶英的生成动力学模型，并与实验结果进行了比较。

In order to confirm that the dibenzo-p-dioxin production channel in combustion is 2C_6H_5O→C_6H_4O_2C_6H_4+2H, high temperature reactions of phenoxy radicals (C_6H_5O) were investigated over the temperature range 1250 - 1700 K using shock-tube techniques. Methoxybenzene (C_6H_5OCH_3) and trifluromethoxybenzene (C_6H_5OCF_3) were used as sources of C_6H_5O radicals. By comparing the experimental results with those by computer simulations, high temperature reactions of C_6H_5O radicals including the dibenzo-p-dioxin production channel were discussed. Reaction products of C_6H_5O decomposition were also analyzed with gas chromatography by sampling the final products behind the reflected shock of C_6H_5OCH_3 and C_6H_5OCF_3 diluted with Ar mixtures. We found that not only the linear hydrocarbons but also aromatic compounds such as phenol were produced behind the shock. However the dibenzo-p-dioxin was not detected as the final products behind the shockwaves of C_6H_5OCH_3 and C_6H_5OCF_3 diluted with Ar mixtures. To simulate the temperature dependence of the yield of dibenzo-p-dioxin production, kinetic model for dibenzo-p-dioxin formation was proposed and compared with the experimental observations.