采用均相反应机理来考察丙烷在热解炭化学气相沉积(CVD)条件下的均相热解反应动力学。提出的反应机理包含285种气相组分和1074个基元反应,其中大部分反应可逆。该反应机理结合全混反应器模型和平推流反应器模型分别形成丙烷热解的0维和1维反应动力学模型,计算得到组分浓度随温度和滞留时间的分布函数,并与实验结果比较。结果表明,此反应机理可以复制出主要产物的形成路径,两个反应模型都能准确地预测小分子随温度和滞留时间的分布函数,并能较好地预测大分子随温度和滞留时间的变化趋势。在1248K和滞留时间为1s条件下,对丙烷的热解进行反应流速率分析并对重要产物进行灵敏度分析,以确定丙烷热解的主要反应路径和重要的反应步骤。最后,讨论如炔丙基、环戊二烯基和茚基等自由基在稠环芳香烃形成过程中起到的重要作用。
The chemical kinetics of propane pyrolysis in chemical vapor deposition (CVD) is investigated in 1074 reactions con sisting of 285 species to understand chemistry of CVD from propane. The reaction mechanism is modeled in a perfectly stirred reac tor and a continuous tubular reactor, to produce a 0-D and a 1-D propane pyrolysis model, respectively. The concentration profiles of gas-phase products in the axial direction of the reactor as functions of temperature and residence time are computed with the DE- TCHEM software package designed for computing time-dependent homogeneous reactions. Comparison between simulated and ex- perimental results shows that the mechanism gives the formation pathway for all major products and can predict the concentration profiles of minor products. Main reaction paths and crucial reaction steps have been determined at 1248 K for ls by analyzing the flux of the main products. The significant roles of radicals such as propargyl, cyclopentadienyl and indenyl in the formation of pol yaromatic hydrocarbons were discussed.