Structure-reactivity correlations for reactions between H/D atoms with selected ethers: Reaction-rate coefficients from direct shock-tube measurements and transition-state theory

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2024-09-19 DOI:10.1016/j.combustflame.2024.113689

F. Werner , C. Naumann , M. Braun-Unkhoff , T. Methling , C. Schulz , U. Riedel , S. Peukert

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引用次数: 0

Abstract

Shock-tube experiments at elevated pressures between 2.0 and 2.7 bar were carried out to study H-atom abstractions between D atoms and selected ether compounds: dimethyl ether (DME), diethyl ether (DEE), dimethoxymethane (DMM), and methyl propyl ether (MPE). D-atom resonance absorption spectrometry (D-ARAS) behind reflected shock waves was used to monitor the consumption of D atoms. To study the bimolecular reactions between D atoms and the specific ether, gas mixtures of the selected ether compound and C₂D₅I diluted in argon (bath gas) were prepared; C₂D₅I was used as a precursor for D atoms. This innovative approach using Dual ARAS (D-ARAS and H-ARAS) allows the distinct detection of precursor decay followed by H-atom abstraction reactions and ether decay followed by H-atom release. For the study of the reaction D + DME → HD + products, the experiments covered a temperature range of 940–1050 K; for the reaction D + DEE → HD + products, the temperature range was 980–1260 K; for the reaction D + DMM → HD + products, the temperature range was 930–1300 K; and for the reaction D + MPE → HD + products, the temperature spans a range of 1000–1350 K. Experimentally determined rate coefficients have been expressed by the following Arrhenius equations:

k_total_(D+DME)(T) = 1.9×10⁻¹⁰ exp (−31.4 kJ/mol / RT) cm³s⁻¹,

k_total_(D+DEE)(T) = 1.7×10⁻¹⁰ exp (−22.4 kJ/mol / RT) cm³s⁻¹,

k_total_(D+DMM)(T) = 2.7×10⁻¹⁰ exp (−27.3 kJ/mol / RT) cm³s⁻¹,

and k_total_(D+MPE)(T) = 5.1×10⁻¹⁰ exp (−31.5 kJ/mol / RT) cm³s⁻¹.

The experimental results show an uncertainty of ±30 % and were supplemented by transition-state theory (TST) calculations based on molecular properties and energies from computations at the G4 level of theory. TST computations were conducted for H-atom abstraction from various types of primary and secondary carbon bonds. Bond-specific reaction rate-coefficient expressions were derived from theory and compared with experimental results to establish correlations between molecular structure and reactivity.

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H/D 原子与特定醚发生反应的结构-反应相关性：直接冲击管测量和过渡态理论得出的反应速率系数

在 2.0 至 2.7 巴的高压下进行了冲击管实验，以研究 D 原子与选定的醚化合物（二甲醚 (DME)、二乙醚 (DEE)、二甲氧基甲烷 (DMM) 和甲基丙基醚 (MPE)）之间的 H 原子抽取。利用反射冲击波背后的 D 原子共振吸收光谱（D-ARAS）来监测 D 原子的消耗。为了研究 D 原子和特定醚之间的双分子反应，制备了选定醚化合物和在氩气（浴气）中稀释的 C2D5I 的气体混合物；C2D5I 被用作 D 原子的前体。这种使用双原子吸收光谱分析仪（D-ARAS 和 H-ARAS）的创新方法可以对前体衰变后的 H 原子抽取反应和醚衰变后的 H 原子释放反应进行不同的检测。在研究 D + DME → HD + 产物反应时，实验温度范围为 940-1050 K；在研究 D + DEE → HD + 产物反应时，温度范围为 980-1260 K；在研究 D + DMM → HD + 产物反应时，温度范围为 930-1300 K；在研究 D + MPE → HD + 产物反应时，温度范围为 1000-1350 K。实验测定的速率系数用以下阿伦尼乌斯方程表示：ktotal(D+DME)(T) = 1.9×10-10 exp (-31.4 kJ/mol / RT) cm3s-1，ktotal(D+DEE)(T) = 1.7×10-10 exp (-22.4 kJ/mol / RT) cm3s-1，ktotal(D+DMM)(T) = 2.7×10-10 exp (-27.3 kJ/mol / RT) cm3s-1，以及 ktotal(D+MPE)(T) = 5.1×10-10 exp (-31. 5 kJ/mol / RT) cm3s-1。实验结果的不确定性为 ±30 %，并根据 G4 理论水平计算得出的分子性质和能量，通过过渡态理论 (TST) 计算进行了补充。TST 计算针对从各种类型的一级和二级碳键中抽离 H 原子。根据理论推导出了特定键的反应速率系数表达式，并与实验结果进行了比较，从而建立了分子结构与反应性之间的相关性。

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.