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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Detailed modeling of low-temperature propane oxidation: 1. the role of the propyl + O_2 reaction
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Detailed modeling of low-temperature propane oxidation: 1. the role of the propyl + O_2 reaction

机译：低温丙烷氧化的详细模型：1.丙基+ O_2反应的作用

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Accurate description of reactions between propyl radicals and molecular oxygen is an essential prerequisite for modeling of low-temperature propane oxidation because their multiple reaction pathways either accelerate the oxidation process via chain branching or inhibit it by forming relatively stable products. The CBS-QB3 level of theory was used to construct potential energy surfaces for n-C_3H_7 + O_2 and i-C _3H_7 + O_2. High-pressure rate constants were calculated using transition state theory with corrections for tunneling and hindered rotations. These results were used to derive pressure- and temperature-dependent rate constants for the various channels of these reactions under the framework of the Quantum Rice - Ramsperger - Kassel (QRRK) and the modified strong collision (MSC) theories. This procedure resulted in a thermodynamically consistent C_3H_7 + O_2 submechanism, which was either used directly or as part of a larger extended detailed kinetic mechanism to predict the loss of propyl and the product yields of propylene and HO_2 over a wide range of temperatures, pressures, and residence times. The overall good agreement between predicted and experimental data suggests that this reaction subset is reliable and should be able to properly account for the reactions of propyl radicals with O_2 in propane oxidation. It is also demonstrated that for most conditions of practical interest only a small subset of reactions (e.g., isomerization, concerted elimination of HO_2, and stabilization) controls the oxidation kinetics, which makes it possible to considerably simplify the mechanism. Moreover, we observed strong similarities in the rate coefficients within each reaction class, suggesting the potential for development of relatively simple rate constant estimation rules that could be applied to analogous reactions involving hydrocarbon radicals that are too large to allow accurate detailed electronic structure calculations.
机译：准确描述丙基自由基和分子氧之间的反应是建模低温丙烷氧化的必要先决条件，因为它们的多种反应途径要么通过链支化来加速氧化过程，要么通过形成相对稳定的产物来抑制它。理论水平的CBS-QB3用于构造n-C_3H_7 + O_2和i-C _3H_7 + O_2的势能面。使用过渡态理论计算了高压速率常数，并对隧道效应和受阻旋转进行了校正。这些结果用于在量子水稻-Ramsperger-Kassel（QRRK）和改进的强碰撞（MSC）理论的框架下得出这些反应各个通道的压力和温度依赖性速率常数。此过程导致了热力学上一致的C_3H_7 + O_2亚机理，该亚机理可以直接使用，也可以用作较大的扩展详细动力学机制的一部分，以预测在宽广的温度，压力，温度范围内，丙基的损失以及丙烯和HO_2的产物收率。和停留时间。预测数据与实验数据之间的总体良好一致性表明，该反应子集是可靠的，并且应能够正确说明丙烷自由基中丙烷自由基与O_2的反应。还表明，对于大多数实际感兴趣的条件，只有一小部分反应（例如，异构化，协同消除HO 2和稳定化）控制了氧化动力学，这使得可以大大简化机理。此外，我们观察到每个反应类别中速率系数的相似性很强，这表明可能开发相对简单的速率常数估算规则，该规则可应用于涉及烃基的类似反应，该反应太大而无法进行精确的详细电子结构计算。

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