Abstract A widely used detailed reaction mechanism for methane oxidation (Gas Research Institute (GRI) mechanism 2.11) has been analysed, in order to evaluate if reactions were to be added to the mechanism. This mechanism consists of 279 reversible elementary reactions between 48 different species, each with a temperature dependence described by a modified Arrhenius expression. The mechanism was transformed to 558 irreversible reactions, and the rate constants were analysed at a fixed temperature, to reduce the complexity of the analysis. A partial least squares (PLS) model was generated, which estimated reaction rate constants as a function of a reaction descriptor vector. This vector characterized the different chemical bonds in the reactants and products of a chemical reaction. The model was validated through full cross validation. The original mechanism was unable to correctly predict oxidation of methane in a natural gas engine exhaust manifold: Oxidation of 2300 ppm methane in the presence of 300 ppm NO, 9% oxygen and 2% water. Therefore, these conditions were used for evaluation of the reaction mechanism. The potential reactions for expanding the mechanism were selected among reactions with one or two reactants and one or two products. A stepwise analysis combining rate of production (ROP) analysis with sensitivity analysis was used to reduce 2138 potential elementary reactions to nine important reactions, which were added to the mechanism. The analysis was based on PLS estimates of the reaction rate constants, but in the final model, literature values were included where available. This modification of the mechanism improved model predictions.

中文翻译：

---

甲烷氧化的详细化学反应机理的化学计量分析

摘要 分析了广泛使用的甲烷氧化详细反应机理（气体研究所（GRI）机理 2.11），以评估是否将反应添加到该机理中。这种机制由 48 种不同物种之间的 279 个可逆基本反应组成，每个反应都具有由修改后的 Arrhenius 表达式描述的温度依赖性。将机理转化为558个不可逆反应，在固定温度下分析速率常数，降低分析复杂度。生成了偏最小二乘 (PLS) 模型，该模型估计反应速率常数作为反应描述符向量的函数。该载体表征了化学反应的反应物和产物中的不同化学键。该模型通过完全交叉验证进行了验证。原始机制无法正确预测天然气发动机排气歧管中甲烷的氧化：在 300 ppm NO、9% 氧气和 2% 水的存在下氧化 2300 ppm 甲烷。因此，这些条件被用于评价反应机理。在与一种或两种反应物和一种或两种产物的反应中选择用于扩展机制的潜在反应。使用生产率 (ROP) 分析与敏感性分析相结合的逐步分析，将 2138 个潜在的基本反应减少到 9 个重要反应，并将其添加到机制中。该分析基于反应速率常数的 PLS 估计，但在最终模型中，如果可用，则包括文献值。这种机制的修改改进了模型预测。