Elementary reactions of formyl (HCO) radical studied by laser photolysis—transient absorption spectroscopy

Krasnoperov, Lev N.; Чесноков, Е. Н.; Stark, Harald; Ravishankara, A. R.

doi:10.1016/j.proci.2004.08.223

Cited by 41 publications

(32 citation statements)

References 33 publications

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“…Low‐pressure limit k 4 values were represented with an Arrhenius expression, k 4 = 4.3 × 10 13 exp (−7818 K/ T ) [Ar]/s. An RRKM fit for these experimental data gives k 4 = 4.8 × 10 17 T –1.2 exp (−8925 K/ T ) [Ar]/s over T = 600 ~ 2500 K. Krasnoperov et al also photolyzed CH 3 CHO in He buffer gas for generation of HCO and measured [HCO] t using an absorption spectroscopy at conditions of T = 498 ~ 769 K and P = 0.8 ~ 100 bar. The second‐order rate coefficient expression at P = 1 bar is k 4 = 4.8 × 10 13 exp (−7938 K/ T ) cm 3 /mol/s.…”

Section: Discussionmentioning

confidence: 98%

“…In the previous studies, the rate coefficients of R 2 (HCO + O 2 → HO 2 + CO) and R 4 (HCO (+M) → H + CO (+M)) were obtained in the separated and independent systems . As stated above, in lean methane combustion the rates of chain initiation and chain growth are dependent upon the competition between R 1 (CH 4 + O 2 → HO 2 + CH 3 ) and R 3 (CH 4 (+M) → H + CH 3 (+M)) in the induction zone and R 2 (HCO + O 2 → HO 2 + CO) and R 4 (HCO (+M) → H + CO (+M)) in the main reaction zone.…”

Section: Introductionmentioning

confidence: 94%

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Determination of the Rate Coefficients of the CH₄ + O₂ → HO₂ + CH₃ and HCO + O₂ → HO₂ + CO Reactions at High Temperatures

Ryu

Shin

Hwang

2017

Bulletin Korean Chem Soc

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Rate coefficients of the title reactions, R1 (CH4 + O2 → HO2 + CH3) and R2 (HCO + O2 → HO2 + CO) were obtained over T = 1610 ~ 1810 K and T = 200 ~ 1760 K, respectively, and at ρ = 7.1 µmol/cm3. A lean CH4/O2/Ar mixture (0.1% CH4, ϕ = 0.02) was heated behind reflected shock waves and the temporal OH absorption profiles were measured using a laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the experimental profiles via optimization of k1 and k2 values in the reaction simulation. The rate coefficient expressions derived are k1 = 1.46 × 1014 exp (−26 210 K/T) cm3/mol/s, T = 1610 ~ 1810 K and k2 = 1.9 × 1012 T0.176 exp (−245 K/T) cm3/mol/s, T = 200 ~ 1760 K.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 94%

Determination of the Rate Coefficients of the CH₄ + O₂ → HO₂ + CH₃ and HCO + O₂ → HO₂ + CO Reactions at High Temperatures

Ryu

Shin

Hwang

2017

Bulletin Korean Chem Soc

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“…Subsequent laser-photolysis shock tube experiments by Friedrich et al [12] at higher temperatures (835-1230 K) and pressures (0.25-1.9 atm) assumed that k 3 was in the lowpressure limit and their results were in discord with Timonen et al [11]. Discrepancies in the thermal rate constant and the extent of fall-off for reaction (3) persisted despite two subsequent higher pressure studies by Hippler et al [13] and Krasnoperov et al [14]. The sparsity of the density of states for HCO, due to it being a small, weakly-bound radical, leads to difficulties in theoretical analyses for the thermal kinetics of reaction (3).…”

Section: Word Countmentioning

confidence: 99%

Ramifications of including non-equilibrium effects for HCO in flame chemistry

Labbe

Sivaramakrishnan

Goldsmith

et al. 2017

Proceedings of the Combustion Institute

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The formation and destruction pathways of the formyl radical (HCO) occupy a pivotal role in the conversion of fuel molecules (and their intermediates) to eventual products CO and CO 2 , and therefore, HCO has been a prescient indicator for heat release in combustion. In this work, we have characterized the impact of including non-equilibrium effects for HCO, i.e. "prompt" dissociation of HCO to H + CO, in simulations of laminar flame speeds for archetypal hydrocarbon and oxygenated molecules relevant to combustion. Prompt dissociation probabilities for HCO were systematically applied to all elementary reactions that included this radical (as either a product or reactant) in literature combustion kinetics models. Simulations with the prompt HCO dissociation corrected models predicted a 7-13% increase in laminar flame speeds at 1 atm for the fuels characterized here (CH 4 , n-C 7 H 16 , CH 3 OH, CH 3 OCH 3) relative to the predictions using the original models. It is evident that simulations of other fuel-air flames at 1 atm will be similarly impacted, suggesting the indispensability of incorporating these nonequilibrium effects for predictive flame modeling. Simulations of higher pressure (10 atm) heptane-air flames predicted a more modest effect (< 5%) of incorporating these non-equilibrium effects. Additionally, species profiles in low-pressure (0.03 atm) flames of CH 2 O and auto-ignition delay simulations (1.4 atm) for CH 2 O-O 2-Ar mixtures were also impacted to a noticeable extent. Lastly, it is also worth noting that prompt dissociations are a ubiquitous feature of all weakly-bound radicals; the kinetics of many of which (C 2 H 3 , C 2 H 5 , CH 3 O, CH 2 OH, etc.) are central to our current understanding of combustion chemistry. Theory/modeling studies are in progress to address the relevance of prompt dissociations in these weakly-bound radicals to combustion modeling.

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“…The interest in the reaction between the

CO

molecule and the

normalH

atom comes from its relevant processes in atmospheric chemistry . In particular, one of the products of this reaction, formyl radical

HCO

, is an important molecule in many fields like atmospheric chemistry, combustion science, and interstellar space . The nature of the interaction between

normalH

atoms and

CO

has been investigated through studies of collisions between these species .…”

Section: Introductionmentioning

confidence: 99%

Thermal rate constant for the C(³P) + OH(X²Π) → CO(X¹Σ) + H(²S) reaction using stochastic energy grained master equation method

Albernaz

Silva

Barreto

et al. 2019

Int J of Chemical Kinetics

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In the present work, the kinetic mechanism of the reaction is studied. The rate constants were determined using the Master Equation Solver for Multi-Energy Well Reactions (MESMER). The master equation modeling was also employed to examine the pressure dependence for each pathway involved. The theoretical analysis shows that the overall rate coefficient is practically independent of pressure up to 100 Torr for the temperature range 125-500 K. The unusual dependence of the overall rate constant with temperature was fit with the -Arrhenius expression ( ) = [1 − ⋅ 0 ] 1 , where = 5.21 × 10 −11 cm 3 molecule −1 s −1 , = 2.12, and 0 = −0.749 kJ⋅mol −1 , for 125≤ T ≤ 500 K. The thermal rate constant results are in relatively good agreement with other theoretical studies. K E Y W O R D SC+OH reaction, HCO and HOC radicals, thermal rate constant, master equation 590

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Elementary reactions of formyl (HCO) radical studied by laser photolysis—transient absorption spectroscopy

Cited by 41 publications

References 33 publications

Determination of the Rate Coefficients of the CH₄ + O₂ → HO₂ + CH₃ and HCO + O₂ → HO₂ + CO Reactions at High Temperatures

Determination of the Rate Coefficients of the CH₄ + O₂ → HO₂ + CH₃ and HCO + O₂ → HO₂ + CO Reactions at High Temperatures

Ramifications of including non-equilibrium effects for HCO in flame chemistry

Thermal rate constant for the C(³P) + OH(X²Π) → CO(X¹Σ) + H(²S) reaction using stochastic energy grained master equation method

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Elementary reactions of formyl (HCO) radical studied by laser photolysis—transient absorption spectroscopy

Cited by 41 publications

References 33 publications

Determination of the Rate Coefficients of the CH4 + O2 → HO2 + CH3 and HCO + O2 → HO2 + CO Reactions at High Temperatures

Determination of the Rate Coefficients of the CH4 + O2 → HO2 + CH3 and HCO + O2 → HO2 + CO Reactions at High Temperatures

Ramifications of including non-equilibrium effects for HCO in flame chemistry

Thermal rate constant for the C(3P) + OH(X2Π) → CO(X1Σ) + H(2S) reaction using stochastic energy grained master equation method

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Determination of the Rate Coefficients of the CH₄ + O₂ → HO₂ + CH₃ and HCO + O₂ → HO₂ + CO Reactions at High Temperatures

Determination of the Rate Coefficients of the CH₄ + O₂ → HO₂ + CH₃ and HCO + O₂ → HO₂ + CO Reactions at High Temperatures

Thermal rate constant for the C(³P) + OH(X²Π) → CO(X¹Σ) + H(²S) reaction using stochastic energy grained master equation method