Experimental and Modeling Study of Low Temperature Oxidation of Iso-propylbenzene with JSR

Oxidation
of iso-propylbenzene (IPB) has been studied over the
temperature range from 700 to 1100 K in a jet-stirred reactor (JSR)
at low-temperature, which is operated at atmospheric pressure from
fuel-lean to fuel-rich condition with residence time from 1.06 to
1.67 s. Reactants and 25 species were identified and quantified by
online GC-MS and GC analysis. A new model involving 306 species and
1985 reactions for low-temperature oxidation of IPB was developed,
whose predictions were in good agreement with the measured profiles
of mole fraction. Sensitivity analysis indicates that the primary
H atom abstraction from the side iso-propyl chain has significant
promoting effect and H-abstraction from the tertiary site of side
iso-propyl tends to play an inhibiting effect under fuel-lean and
fuel-rich cases. The predominant consumption pathway of IPB proceeds
through primary benzylic H atom abstraction to form iso-phenylpropyl
radicals for both fuel-lean and fuel-rich cases. However, compared
to the fuel-rich condition, 1-iso-phenylpropyl is favorable kinetically
under the fuel-lean condition. Both simulated and experimental results
show that styrene and phenol are most abundant and stable monocyclic
aromatic intermediates for IPB oxidation at low-temperature. These
experimental and modeling works will expand the research area of low-temperature
oxidation of IPB and provide insights on understanding the combustion
mechanism of IPB.

本研究在700~1100 K的低温区间内，于常压操作的射流搅拌反应器（jet-stirred reactor, JSR）中开展了异丙苯（iso-propylbenzene, IPB）的氧化反应研究，实验工况覆盖贫燃至富燃范围，停留时间设置为1.06~1.67 s。实验通过在线气相色谱-质谱联用（GC-MS）与气相色谱（GC）分析，对反应物及25种组分完成了定性与定量检测。本研究构建了包含306种组分与1985个反应步骤的IPB低温氧化新模型，该模型的预测结果与实测摩尔分数分布吻合度良好。敏感性分析结果显示，在贫燃与富燃工况下，从异丙基侧链发生的一级氢抽提反应具有显著促进作用，而从侧链叔碳位点发生的氢抽提反应则倾向于产生抑制效果。无论贫燃还是富燃工况，IPB的主要消耗路径均为一级苄基氢抽提反应，生成异苯丙基自由基。但相较于富燃工况，贫燃工况下1-异苯丙基自由基在动力学层面更具优势。模拟与实验结果均表明，苯乙烯（styrene）与苯酚（phenol）是IPB低温氧化过程中丰度最高且最稳定的单环芳香族中间体。本项实验与模型研究将拓展IPB低温氧化的研究范畴，为深入理解IPB的燃烧机理提供理论参考。