Constante de vitesse à 298 K de la réaction d'oxydation du méthanol par l'oxygène atomique

Lalo, C.; Vermeil, C.

doi:10.1051/jcp/1980770131

Cited by 9 publications

(7 citation statements)

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“…Measurements of the overall rate for the reaction of methanol with atomic oxygen, e.g., 73–77, are in reasonable agreement except near room temperature, where the data deviate by more than a factor of 10. In the present mechanism, the recommendation of Baulch et al 36 is combined with a temperature independent branching ratio k 5 /(k 4 + k 5 ) = 0.15, similar to the values applied for CH 3 OH + OH and CH 3 OH + H.…”

Section: Chemical Kinetic Modelmentioning

confidence: 68%

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Rasmussen

Wassard

Dam‐Johansen

et al. 2008

Int J of Chemical Kinetics

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The oxidation of methanol in a flow reactor has been studied experimentally under diluted, fuel-lean conditions at 650-1350 K, over a wide range of O 2 concentrations (1%-16%), and with and without the presence of nitric oxide. The reaction is initiated above 900 K, with the oxidation rate decreasing slightly with the increasing O 2 concentration. Addition of NO results in a mutually promoted oxidation of CH 3 OH and NO in the 750-1100 K range. The experimental results are interpreted in terms of a revised chemical kinetic model. Owing to the high sensitivity of the mutual sensitization of CH 3 OH and NO oxidation to the partitioning of CH 3 O and CH 2 OH, the CH 3 OH + OH branching fraction could be estimated as α = 0.10 ± 0.05 at 990 K. Combined with low-temperature measurements, this value implies a branching fraction that is largely independent of temperature. It is in good agreement with recent theoretical estimates, but considerably lower than values employed in previous modeling studies. Modeling predictions with the present chemical kinetic model is in quantitative agreement with experimental results below 1100 K, but at higher temperatures and high O 2 concentration the model underpredicts the oxidation rate.

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Section: Chemical Kinetic Modelmentioning

confidence: 68%

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Rasmussen

Wassard

Dam‐Johansen

et al. 2008

Int J of Chemical Kinetics

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“…Several experimental studies of the kinetics of R1 and R2 have been reported. 9,10,11,12,13,14,15,16,17 The experimental total rate constants k 1+2 are plotted as functions of temperature in Figure 1. Lu et al 15 used a diaphragmless shock tube with atomic resonance absorption detection of O atoms and evaluated the rate constants in the temperature range of 835-1777 K; the other experiments were conducted under 1006 K, where our studies indicate that only reaction R1 contributes non-negligibly.…”

Section: Introductionmentioning

confidence: 99%

“…The present article considers the reactions between methanol and atomic oxygen O( 3 P): Production of CH 3 • + HO 2 , which has a much higher activation energy, is not considered in this work. Several experimental studies of the kinetics of reactions R1 and R2 have been reported. − The experimental total rate constants k 1+2 are plotted as functions of temperature in Figure . Lu et al used a diaphragmless shock tube with atomic resonance absorption detection of O atoms and evaluated the rate constants in the temperature range 835–1777 K; the other experiments were conducted under 1006 K, where our studies indicate that only reaction R1 contributes non-negligibly.…”

Section: Introductionmentioning

confidence: 99%

Computational Kinetics by Variational Transition-State Theory with Semiclassical Multidimensional Tunneling: Direct Dynamics Rate Constants for the Abstraction of H from CH₃OH by Triplet Oxygen Atoms

Meana-Pañeda

et al. 2017

J. Phys. Chem. A

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Rate constants and the product branching ratio for hydrogen abstraction from CHOH by O(P) were computed with multistructural variational transition-state theory including microcanonically optimized multidimensional tunneling. Benchmark calculations of the forward and reverse classical barrier heights and the reaction energetics have been carried out by using coupled cluster theory and multireference calculations to select the most reliable density functional method for direct dynamics computations of the rate constants. The dynamics calculations included the anharmonicity of the zero-point energies and partition functions, with specific-reaction-parameter scaling factors for reactants and transition states, and multistructural torsional anharmonicity was included for the torsion around the C-O bond in methanol and in the transition states. The resulting rate constants are presented over a wider range than they are available from experiment, but in the temperature range where experiments are available, they agree well with experimental values, which is encouraging for their reliability over the wider temperature range and for future computations of oxygen atom reaction rates. In contrast to a previous computational prediction, the branching ratio predicted by the present work shows that the formation of CHOH + OH is the dominant channel over the whole range of temperature from 250 to 2000 K.

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“…Experimentally, the title reaction has been extensively studied using a wide variety of detection techniques and a broad range of temperatures (300−2060 K). − To clarify the discussion, this temperature range will be split into three regions. At low temperatures ( T < 400 K), the reaction mechanism (H-abstraction producing NH 2 and OH or O-addition producing a NH 3 O* excited complex) is still an open question. ,,, The largest number of studies has been performed at intermediate temperatures (500−1000 K). − , The high degree of dispersion of the rate constant values diminishes with temperature. For example, at 500 K, the rate constants range from 1.17 × 10 -14 cm 3 molecule -1 s -1 (ref ) to 3.83 × 10 -15 cm 3 molecule -1 s -1 (ref ), that is, by a factor of 3.…”

Section: Introductionmentioning

confidence: 99%

Reaction-Path Dynamics Calculations of the NH₃ + O(³P) Hydrogen Abstraction Reaction

Espinosa‐García

2000

J. Phys. Chem. A

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Molecular orbital theory was used to study the stationary points on the reaction-path of the hydrogen abstraction reaction between ammonia and an oxygen atom. In the C s symmetry, this reaction proceeds over two potential energy surfaces, 3 A′ and 3 A′′, with a hydrogen-bonded complex in the exit channel. From the analysis of the reaction-path curvature, we find qualitatively that excitation of the NH 3 stretch and bend modes might enhance the forward rate constants and that the OH stretch and NH 2 bend modes of the products could appear vibrationally excited, although, as a result of the randomization of the energy favored by the deep hydrogenbonded well, these modes will appear less vibrationally excited than those in other direct reactions. The total forward thermal rate constants were calculated from the sum of the calculated rate constants for the two surfaces using variational transition-state theory with semiclassical transmission coefficients over a wide temperature range, 500-2000 K. The calculated rate constants show reasonable agreement with experimental data, with a more pronounced curvature in the Arrhenius plot than in the experimental data.

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Constante de vitesse à 298 K de la réaction d'oxydation du méthanol par l'oxygène atomique

Cited by 9 publications

References 0 publications

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Computational Kinetics by Variational Transition-State Theory with Semiclassical Multidimensional Tunneling: Direct Dynamics Rate Constants for the Abstraction of H from CH₃OH by Triplet Oxygen Atoms

Reaction-Path Dynamics Calculations of the NH₃ + O(³P) Hydrogen Abstraction Reaction

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Constante de vitesse à 298 K de la réaction d'oxydation du méthanol par l'oxygène atomique

Cited by 9 publications

References 0 publications

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH3OH+OH reaction

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH3OH+OH reaction

Computational Kinetics by Variational Transition-State Theory with Semiclassical Multidimensional Tunneling: Direct Dynamics Rate Constants for the Abstraction of H from CH3OH by Triplet Oxygen Atoms

Reaction-Path Dynamics Calculations of the NH3 + O(3P) Hydrogen Abstraction Reaction

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Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Methanol oxidation in a flow reactor: Implications for the branching ratio of the CH₃OH+OH reaction

Computational Kinetics by Variational Transition-State Theory with Semiclassical Multidimensional Tunneling: Direct Dynamics Rate Constants for the Abstraction of H from CH₃OH by Triplet Oxygen Atoms

Reaction-Path Dynamics Calculations of the NH₃ + O(³P) Hydrogen Abstraction Reaction