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Theoretical study on COS oxidation mechanism
Combustion and Flame ( IF 4.4 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.combustflame.2020.07.039
Tianshuang Li , Jie Li , Hongliang Zhang , Shuai Yang , Jingkun Wang , Jin Xiao

Abstract COS is the most abundant sulfur containing compound in the atmosphere that could cause serious adverse effects on human health and environment. Understanding the oxidation mechanism of COS is with great significance in controlling and utilization reduced sulfur (CS2 and COS). In this study, density function theory (DFT) and multi-reference configuration interaction with Davidson correction (MRCI+Q) methods were adopted to investigate the oxidation mechanism of COS. All energies were refined at CCSD(T)/CBS level and subsequently used to deduce the kinetic parameters. The critical mechanism was validated by experiments results. It was found that the oxidation of COS is initiated through three channels. In COS+COS channel, S2(a1∆g) is first produced and then oxidized to SO(X3Σ). In COS+O2 channel, COS combines O2(X3Σg) to yield SO(X3Σ, a1∆) and CO2(X1Σg). In COS dissociation channel, atomic sulfur S(3P, 1D) will be primarily generated and subsequently oxidized to SO(X3Σ) and O(3P). Oxidation of SO(X3Σ) could either result in O(3P) formation. At higher COS concentration, O(3P) formed through three initiation channels will react with COS to produce S(3P) and SO(X3Σ), both of which will be oxidized finally to SO2(X1A1) to reproduce O(3P). Reaction of COS+O(3P) is the dominating consumption reaction of COS. The major products of COS oxidation are CO(a1∆) and CO2(X1Σg) and SO2(X1A1). The ratio of CO/CO2 in products is mainly affected by the branching fraction of COS+O(3P). Based on the rate coefficient calculated at CCSD(T)/CBS level, a comprehensive kinetic model was developed to predict the COS oxidation process. The modeling results are in agreement with experiment data.

中文翻译:

COS氧化机理的理论研究

摘要 COS 是大气中含量最丰富的含硫化合物,会对人类健康和环境造成严重的不利影响。了解COS的氧化机理对于控制和利用还原硫(CS2和COS)具有重要意义。本研究采用密度函数理论 (DFT) 和多参考构型相互作用与戴维森校正 (MRCI+Q) 方法来研究 COS 的氧化机制。所有能量均在 CCSD(T)/CBS 级别进行细化并随后使用推导出动力学参数。实验结果验证了关键机制。发现COS的氧化是通过三个通道引发的。在 COS+COS 通道中,首先产生 S2(a1Δg),然后氧化成 SO(X3Σ)。在 COS+O2 通道中,COS 结合 O2(X3Σg) 生成 SO(X3Σ, a1∆) 和 CO2(X1Σg)。在 COS 解离通道中,原子硫 S(3P, 1D) 将主要生成并随后被氧化为 SO(X3Σ) 和 O(3P)。SO(X3Σ) 的氧化可能导致 O(3P) 的形成。在较高的 COS 浓度下,通过三个起始通道形成的 O(3P) 将与 COS 反应生成 S(3P) 和 SO(X3Σ),两者最终都会被氧化为 SO2(X1A1) 以再生 O(3P)。COS+O(3P)反应是COS的主要消耗反应。COS氧化的主要产物是CO(a1∆)和CO2(X1Σg)和SO2(X1A1)。产物中CO/CO2的比例主要受COS+O(3P)支化率的影响。基于CCSD(T)/CBS水平计算的速率系数,开发了综合动力学模型来预测COS氧化过程。建模结果与实验数据一致。
更新日期:2020-11-01
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