A theoretical and shock tube kinetic study on hydrogen abstraction from phenyl formate

Ning, Hongbo; Liu, Dapeng; Wu, Junjun; Ma, Liuhao; Ren, Wei; Farooq, Aamir

doi:10.1039/c8cp02075b

Cited by 14 publications

(7 citation statements)

References 27 publications

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“…For the abstraction reactions by OH radical, rate constants calculations need to consider the formed Van der Waals complexes (RCs and PCs), and two-TS models are usually employed [21,22]. However, a series of previous studies indicated that this model only showed significant effect at low temperatures below 200 K [21,22,23,24,25,26]. For the interested combustion relevant temperature range of 500–2500 K, the rate-limiting step is the inner TSs.…”

Section: Resultsmentioning

confidence: 99%

Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Wang

Sun

et al. 2019

IJMS

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Hydrogen atom abstraction from propargyl C-H sites of alkynes plays a critical role in determining the reactivity of alkyne molecules and understanding the formation of soot precursors. This work reports a systematic theoretical study on the reaction mechanisms and rate constants for hydrogen abstraction reactions by hydrogen and hydroxy radicals from a series of alkyne molecules with different structural propargyl C-H atoms. Geometry optimizations and frequency calculations for all species are performed at M06-2X/cc-pVTZ level of theory and the hindered internal rotations are also treated at this level. The high-level W1BD and CCSD(T)/CBS theoretical calculations are used as a benchmark for a series of DFT calculations toward the selection of accurate DFT functionals for large reaction systems in this work. Based on the quantum chemistry calculations, rate constants are computed using the canonical transition state theory with tunneling correction and the treatment of internal rotations. The effects of the structure and reaction site on the energy barriers and rate constants are examined systematically. To the best of our knowledge, this work provides the first systematic study for one of the key initiation abstraction reactions for compounds containing propargyl hydrogen atoms.

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Section: Resultsmentioning

confidence: 99%

Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Wang

Sun

et al. 2019

IJMS

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“…Such complexes can be easily located via IRC analysis. 54,55 Figure 4 shows a complete potential energy diagram for MCH + OH at the tertiary site at the DLPNO-CCSD(T)/CBS//M06-2X/cc-pVTZ level. It can be seen that lower energy van der Waals complexes are formed at the entrance and exit channels for this reaction.…”

Section: Theoretical Calculation Resultsmentioning

confidence: 99%

“…It can be seen that lower energy van der Waals complexes are formed at the entrance and exit channels for this reaction. However, these complexes are not kinetically important under the studied high temperature conditions, [54][55][56] which is not considered during rate constant calculations. Based on the computed energy barriers together with frequency analysis results, the rate constants of the studied 30 abstraction reactions are computed considering the tunneling corrections and international rotations.…”

Section: Theoretical Calculation Resultsmentioning

confidence: 99%

Ab initio kinetic study on the abstraction reactions of methylcyclohexane and implications for high‐temperature ignition simulations from shock tube experiment

Liang,

Jia,

Yao

et al. 2024

Int J of Chemical Kinetics

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Methylcyclohexane (MCH) is the simplest alkylated cyclohexane, and has been widely employed in surrogate models to represent the cycloalkanes in real fuels. Thus, extensive experimental and kinetic modeling studies have been performed to understanding the combustion chemistry of MCH. However, through a detailed literature analysis, there still lack a systematic theoretical study on the abstraction reactions of MCH, which are the main initial oxidation pathway of MCH. Herein, this work reports a systematic ab initio chemical kinetic study on the abstraction reactions of MCH with different radicals/species. Specifically, reaction rate constants of 30 abstraction reactions of MCH with H/O/OH/O2/HO2/CH3 at different sites are computed using transition state theory (TST) by using quantum chemistry calculation results at DLPNO‐CCSD(T)/CBS//M06‐2X/cc‐pVTZ level. The computed results are incorporated into a detailed mechanism to simulate newly measured ignition delay times (IDTs) of MCH in this work at equivalence ratios of 0.5, 1.0, and 2.0, pressures of 2 and 5 bar, temperatures ranging from 1140 to 1640 K. The updated detailed mechanism demonstrates improvement in the prediction of IDTs, especially at fuel‐rich conditions. The fuel concentration and dilution effect on the IDTs are discussed, and a general Arrhenius expression is adopted to fit the IDTs from both this work and literature work. This work should be valuable for further optimization of detailed kinetic mechanisms and also for gaining insight into the combustion chemistry of MCH.

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“…The reason behind all these observations can be attributed to accessibility of more rovibronic energy levels when the J value is higher . From the microcanonical perspective, it is equivalent to increasing the sum of states for the TSs of the individual reaction paths (see eq ), and, from the thermodynamics point of view, accessibility of more rovibronic levels increases the entropy of the TSs and, therefore, the rate of the reactions. , The selected J values can also lead to different sets of branching ratios based on Tables S11 and S12. In fact, the increase of J significantly alters the branching ratios of the main products, respectively, toward a higher and lower extent of 2 HOC + 2 H and 2 HCO + 2 H production.…”

Section: Results and Discussionmentioning

confidence: 99%

“…116 From the microcanonical perspective, it is equivalent to increasing the sum of states for the TSs of the individual reaction paths (see eq 1), and, from the thermodynamics point of view, accessibility of more rovibronic levels increases the entropy of the TSs and, therefore, the rate of the reactions. 117,118 The S13 and S14. selected J values can also lead to different sets of branching ratios based on Tables S11 and S12.…”

Section: ■ Methodsmentioning

confidence: 99%

Chemical Kinetics Approves the Occurrence of C (³P_j) Reaction with H₂O

Keshavarz

2019

J. Phys. Chem. A

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Although both atomic carbon and water are omnipresent in human life, there is a debate about the possibility of carbon reaction with water. Some low-temperature spectroscopic investigations have rejected the reaction, whereas some room-temperature experiments and theoretical studies have accepted the possibility of the reaction by reporting rate coefficients ranging from 105 to 109 L mol–1 s–1. This study provides new lines of evidence about the reaction through exploration of the reaction mechanism using the CCSD(T) method and solving the corresponding master equation by following two main approaches. According to the results, the rate coefficient of the reaction is significantly influenced by the tunneling and hindered rotation effects, in addition to the selected total angular momentum (J). Furthermore, the total rate coefficient of the reaction increases dramatically (from 107 to 1011 L mol–1 s–1) with the rise of temperature from 100 to 4000 K, while the total rate coefficient is insensitive to pressure (0.1–10 atm). Despite some differences between the results of the two approaches, the rate coefficients of both methods are consistent with the previously reported rate coefficients. Also, in agreement with the previous studies, the major products are 2HOC + 2H and 2HCO + 2H. In general, the findings approve the occurrence of the title reaction and indicate that the mentioned conflict is due to the sensitivity of the reaction to the investigated temperature and J level. The sensitivity does not permit low-temperature spectroscopic studies to detect any products and varies the measured and calculated rate coefficients.

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A theoretical and shock tube kinetic study on hydrogen abstraction from phenyl formate

Cited by 14 publications

References 27 publications

Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Ab initio kinetic study on the abstraction reactions of methylcyclohexane and implications for high‐temperature ignition simulations from shock tube experiment

Chemical Kinetics Approves the Occurrence of C (³P_j) Reaction with H₂O

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A theoretical and shock tube kinetic study on hydrogen abstraction from phenyl formate

Cited by 14 publications

References 27 publications

Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Chemical Kinetics of Hydrogen Atom Abstraction from Propargyl Sites by Hydrogen and Hydroxy Radicals

Ab initio kinetic study on the abstraction reactions of methylcyclohexane and implications for high‐temperature ignition simulations from shock tube experiment

Chemical Kinetics Approves the Occurrence of C (3Pj) Reaction with H2O

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Chemical Kinetics Approves the Occurrence of C (³P_j) Reaction with H₂O