Effects of stereoisomeric structure and bond location on the ignition and reaction pathways of hexenes
Effects of stereoisomeric structure and bond location on the ignition and reaction pathways of hexenes
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DOI：
10.1002/kin.21442
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发表时间：
2020-09
影响因子：
1.5
通讯作者：
César L. Barraza-Botet;Chang-Hui Liu;John H. Kim;S. Wagnon;M. Wooldridge
中科院分区：
文献类型：
--
作者：
César L. Barraza-Botet;Chang-Hui Liu;John H. Kim;S. Wagnon;M. Wooldridge
本文介绍了顺-2-己烯和顺-3-己烯两种顺-己烯异构体的新实验自燃和形态数据。新的数据提供了碳碳双键位置和立体异构体结构对线性己烯异构体的点火延迟时间和反应途径的影响。利用密歇根大学的快速压缩设备进行了实验，从压力-时间历史中确定了点火延迟时间。在平均压力为11 atm，温度为809至1052 K的条件下，在惰性气体对O2的稀释水平为7.5:1（摩尔基础）的化学计量（φ = 1.0）混合物进行了研究。在T = 900 K下对两种顺己烯异构体进行了物种形成实验，采用快速气相取样和气相色谱法对两种顺己烯异构体和稳定的中间物质进行了鉴定和定量。点火延迟时间数据对碳碳双键位置和立体异构体结构（顺反）的敏感性可以忽略不计，物种数据与立体异构体结构没有相关性，但某些测量物种与己烯异构体中双键的位置有很强的相关性。其中，2-己烯对丙烯、乙醛和1,3-丁二烯有较强的选择性，3-己烯对丙烯有较强的选择性。模型预测的点火延迟时间与实验数据吻合良好。2-己烯的物种数据与模型预测基本一致；然而，该机制高估了3-己烯的一些小醛（C2-C4）种。反应路径分析表明，在研究条件下（P = 11atm, T bbb900 K），己烯几乎完全被h原子萃取反应消耗，而不是在高温（>1300 K）己烯点火研究中观察到的C3-C4裂解反应。对3-己烯+ OH反应的改进估计可能会改进本工作中测量的物种的模型预测。
The current work presents new experimental autoignition and speciation data on the two cis-hexene isomers: cis-2-hexene and cis-3-hexene. The new data provide insights on the effects of carbon-carbon double bond location and stereoisomeric structures on ignition delay times and reaction pathways for linear hexene isomers. Experiments were performed using the University of Michigan rapid compression facility to determine ignition delay times from pressure-time histories. Stoichiometric (ϕ = 1.0) mixtures at dilution levels of inert gas to O2 = 7.5:1 (mole basis) were investigated at an average pressure of 11 atm and temperatures from 809 to 1052 K. Speciation experiments were conducted at T = 900 K for the two cis-hexene isomers, where fast-gas sampling and gas chromatography were used to identify and quantify the two cis-hexene isomers and stable intermediate species. The ignition delay time data showed negligible sensitivity to the location of the carbon-carbon double bond and the stereoisomeric structure (cis-trans), and the species data showed no correlation with the stereoisomeric structure, but there was a strong correlation of some of the measured species with the location of the double bond in the hexene isomer. In particular, 2-hexene showed strong selectivity to propene, acetaldehyde, and 1,3-butadiene, and 3-hexene showed selectivity to propanal. Model predictions of ignition delay times were in excellent agreement with the experimental data. There was generally good agreement for the model predictions of the species data for 2-hexene; however, the mechanism overpredicted some of the small aldehyde (C2-C4) species for 3-hexene. Reaction pathway analysis indicates the hexenes are almost exclusively consumed by H-atom abstraction reactions at the conditions studied (P = 11 atm, T > 900 K), and not by C3-C4 scission as observed in high-temperature (>1300 K) hexene ignition studies. Improved estimates for 3-hexene + OH reactions may improve model predictions for the species measured in this work.