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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions
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Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

机译：低温丙烷氧化的多尺度信息学：复杂反应研究中的进一步复杂性

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The present paper describes further development of the multiscale informatics approach to kinetic model formulation of Burke et al. (Burke, M. P.; Klippenstein, S. J.; Harding, L. B. Proc. Combust. Inst. 2013, 34, 547-555) that directly incorporates elementary kinetic theories as a means to provide reliable, physics-based extrapolation of kinetic models to unexplored conditions. Here, we extend and generalize the multiscale informatics strategy to treat systems of considerable complexity-involving multiwell reactions, potentially missing reactions, nonstatistical product branching ratios, and non-Boltzmann (i.e., nonthermal) reactant distributions. The methodology is demonstrated here for a subsystem of low-temperature propane oxidation, as a representative system for low-temperature fuel oxidation. A multiscale model is assembled and informed by a wide variety of targets that include ab initio calculations of molecular properties, rate constant measurements of isolated reactions, and complex systems measurements. Active model parameters are chosen to accommodate both "parametric" and "structural" uncertainties. Theoretical parameters (e.g., barrier heights) are included as active model parameters to account for parametric uncertainties in the theoretical treatment; experimental parameters (e.g., initial temperatures) are included to account for parametric uncertainties in the physical models of the experiments. RMG software is used to assess potential structural uncertainties due to missing reactions. Additionally, branching ratios among product channels are included as active model parameters to account for structural uncertainties related to difficulties in modeling sequences of multiple chemically activated steps. The approach is demonstrated here for interpreting time-resolved measurements of OH, HO2, n-propyl, i-propyl, propene, oxetane, and methyloxirane from photolysis-initiated low-temperature oxidation of propane at pressures from 4 to 60 Torr and temperatures from 300 to 700 K. In particular, the multiscale informed model provides a consistent quantitative explanation of both ab initio calculations and time-resolved species measurements. The present results show that interpretations of OH measurements are significantly more complicated than previously thought-in addition to barrier heights for key transition states considered previously, OH profiles also depend on additional theoretical parameters for R + O-2 reactions, secondary reactions, QOOH + O-2 reactions, and treatment of non-Boltzmann reaction sequences. Extraction of physically rigorous information from those measurements may require more sophisticated treatment of all of those model aspects, as well as additional experimental data under more conditions, to discriminate among possible interpretations and ensure model reliability.
机译：本文描述了Burke等人动力学模型制定的多尺度信息学方法的进一步发展。 （Burke，M.P .; Klippenstein，S.J .; Harding，L.B.Proc.Combust.Inst.2013，34，547-555）直接将基本动力学理论作为一种手段，将动力学模型可靠地基于物理推断到未探索的条件。在这里，我们扩展并推广了多尺度信息学策略，以处理涉及大量复杂性的系统，包括涉及多孔反应，潜在缺失的反应，非统计产物分支比和非玻尔兹曼（即非热）反应物分布的系统。在此演示了该方法用于低温丙烷氧化子系统，作为低温燃料氧化的代表系统。通过多种目标来组装和告知多尺度模型，这些目标包括分子性质的从头计算，离析反应的速率常数测量以及复杂的系统测量。选择活动模型参数以适应“参数”和“结构”不确定性。理论参数（例如，障碍物高度）作为有效模型参数包括在内，以解决理论处理中的参数不确定性;实验参数（例如初始温度）也包括在内，以说明实验物理模型中的参数不确定性。 RMG软件用于评估由于缺少反应而引起的潜在结构不确定性。另外，包括产品通道之间的分支比作为活性模型参数，以解决与对多个化学活化步骤的序列进行建模的困难有关的结构不确定性。此处演示了该方法用于解释在4至60 Torr的压力下以及在60°C的压力下由光解引发的丙烷的低温氧化过程中OH，HO2，正丙基，异丙基，丙烯，氧杂环丁烷和甲基环氧乙烷的时间分辨测量结果300到700K。特别是，多尺度信息模型为从头算和时间分辨物种测量提供了一致的定量解释。目前的结果表明，对OH测量的解释比以前认为的要复杂得多，除了先前考虑的关键过渡态的势垒高度外，OH分布还取决于R + O-2反应，次级反应，QOOH +的其他理论参数。 O-2反应，以及非玻耳兹曼反应序列的处理。从这些测量结果中提取严格的物理信息可能需要对所有这些模型方面进行更复杂的处理，并需要在更多条件下使用其他实验数据，以区分可能的解释并确保模型的可靠性。

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