Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551, USA.
Phys Chem Chem Phys. 2010 Oct 14;12(38):12112-22. doi: 10.1039/c0cp00241k. Epub 2010 Aug 31.
Fuel decomposition and benzene formation processes in a premixed, laminar, low-pressure, fuel-rich flame of 1-hexene (C(6)H(12), CH(2)=CH-CH(2)-CH(2)-CH(2)-CH(3)) are investigated by comparing quantitative mole fraction profiles of flame species with kinetic modeling results. The premixed flame, which is stabilized on a flat-flame burner under a reduced pressure of 30 Torr (= 40 mbar), is analyzed by flame-sampling molecular-beam time-of-flight mass spectrometry which uses photoionization by tunable vacuum-ultraviolet synchrotron radiation. The temperature profile of the flame is measured by OH laser-induced fluorescence. The model calculations include the latest rate coefficients for 1-hexene decomposition (J. H. Kiefer et al., J. Phys. Chem. A, 2009, 113, 13570) and for the propargyl (C(3)H(3)) + allyl (a-C(3)H(5)) reaction (J. A. Miller et al., J. Phys. Chem. A, 2010, 114, 4881). The predicted mole fractions as a function of distance from the burner are acceptable and often even in very good agreement with the experimentally observed profiles, thus allowing an assessment of the importance of various fuel decomposition reactions and benzene formation routes. The results clearly indicate that in contrast to the normal reactions of fuel destruction by radical attack, 1-hexene is destroyed mainly by decomposition via unimolecular dissociation forming allyl (a-C(3)H(5)) and n-propyl (n-C(3)H(7)). Minor fuel-consumption pathways include H-abstraction reactions producing various isomeric C(6)H(11) radicals with subsequent β-scissions into C(2), C(3), and C(4) intermediates. The reaction path analysis also highlights a significant contribution through the propargyl (C(3)H(3)) + allyl (a-C(3)H(5)) reaction to the formation of benzene. In this flame, benzene is dominantly formed through H-assisted isomerization of fulvene, which itself is almost exclusively produced by the C(3)H(3) + a-C(3)H(5) reaction.
在低压富燃料的 1-己烯（C(6)H(12)，CH(2)=CH-CH(2)-CH(2)-CH(2)-CH(3)) 预混层流火焰中，通过比较火焰物种的定量摩尔分数分布与动力学建模结果，研究了燃料分解和苯形成过程。在 30 托（= 40 毫巴）的减压下，在平面火焰燃烧器上稳定的预混火焰通过可调谐真空紫外同步辐射光致电离的火焰取样分子束飞行时间质谱进行分析。通过 OH 激光诱导荧光测量火焰的温度分布。模型计算包括 1-己烯分解的最新速率系数（J. H. Kiefer 等人，J. Phys. Chem. A，2009，113，13570）和炔丙基（C(3)H(3)）+丙烯基（a-C(3)H(5)）反应（J. A. Miller 等人，J. Phys. Chem. A，2010，114，4881）。预测的摩尔分数随燃烧器距离的变化是可以接受的，而且通常甚至与实验观察到的分布非常吻合，从而可以评估各种燃料分解反应和苯形成途径的重要性。结果清楚地表明，与自由基攻击引起的正常燃料破坏反应相反，1-己烯主要通过通过单分子离解形成丙烯基（a-C(3)H(5)）和正丙基（n-C(3)H(7)）的分解而被破坏。次要的燃料消耗途径包括产生各种异构 C(6)H(11)自由基的 H 提取反应，随后β断裂成 C(2)、C(3)和 C(4)中间体。反应路径分析还突出了通过炔丙基（C(3)H(3)）+丙烯基（a-C(3)H(5)）反应对苯形成的重要贡献。在这种火焰中，苯主要通过富烯的 H 辅助异构化形成，而富烯本身几乎完全由 C(3)H(3) + a-C(3)H(5)反应产生。
