Experimental and Modeling Study of the Temperature and Pressure Dependence of the Reaction C2H5 + O2 (+ M) → C2H5O2 (+ M)

Fernandes, Ravi X.; Luther, K.; Marowsky, G.; Rissanen, Matti; Timonen, Raimo S.; Troe, J.

doi:10.1021/jp511672v

Cited by 13 publications

(28 citation statements)

References 41 publications

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“…Ethyl is the smallest alkyl radical for which the R + O 2 potential energy surface exhibits the main features of larger alkyl radicals. Thus, its reaction with O 2 has served as a protopye, with a detailed and quantitative picture of its kinetics derived from extensive experimental [115][116][117][187][188][189][190], electronic structure [191][192][193][194][195][196], and reaction rate theory [117,190,194,[197][198][199][200][201] studies. Building from their early density functional theory analyses [191][192][193], the most important stationary points on the PES were ultimately mapped with a high-level focal point analysis by Schaefer and coworkers [196].…”

Section: Ethyl Radical Oxidationmentioning

confidence: 99%

“…Meanwhile, the pioneering kinetic study of Wagner et al, which illuminated many aspects of the kinetics through model RRKM calculations [190], was followed by extensive master equation analyses by Miller and coworkers [194,199,201]. Most recently, a joint experimental and theory analysis has explored the pressure dependence of the recombination process from 200 -500 K [117].…”

Section: Ethyl Radical Oxidationmentioning

confidence: 99%

“…Plot of the pressure dependence of the room temperature rate constant for C 2 H 5 + O 2  products with He as the bath gas. Symbols denote experimental values from[115,117,[187][188][189][190].…”

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confidence: 99%

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From theoretical reaction dynamics to chemical modeling of combustion

Klippenstein

2017

Proceedings of the Combustion Institute

232

228

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The chemical modeling of combustion treats the chemical conversion of hundreds of species through thousands of reactions. Recent advances in theoretical methodologies and computational capabilities have transformed theoretical chemical kinetics from a largely empirical to a highly predictive science. As a result, theoretical chemistry is playing an increasingly significant role in the combustion modeling enterprise. The accurate prediction of the temperature and pressure dependence of gas phase reactions requires state-of-the-art implementations of a variety of theoretical methods: ab initio electronic structure theory, transition state theory, classical trajectory simulations, and the master equation. In this work, we illustrate the current state-of-the-art in predicting the kinetics of gas-phase reactions through sample calculations for some prototypical reactions central to combustion chemistry. These studies are used to highlight the success of theory, as well as its remaining challenges, through comparisons with experiments ranging from elementary reaction kinetics studies through to global observations such as flame speed measurements. The illustrations progress from the treatment of relatively simple abstraction and addition reactions, which proceed over a single transition state, through to the complexity of multiwell multichannel reactions that commonly occur in studies of the growth of polycyclic aromatic hydrocarbons. In addition to providing high quality rate prescriptions for combustion modelers, theory will be seen to indicate various shortcomings in the foundations of chemical modeling. Future progress in the fidelity of the chemical modeling of combustion will benefit from more widespread applications of theoretical chemical kinetics and from increasingly intimate couplings of theory, experiment, and modeling.

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Section: Ethyl Radical Oxidationmentioning

confidence: 99%

Section: Ethyl Radical Oxidationmentioning

confidence: 99%

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From theoretical reaction dynamics to chemical modeling of combustion

Klippenstein

2017

Proceedings of the Combustion Institute

232

228

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“…This prototypical reaction has features common to the oxidation of many larger hydrocarbons. 47,48 It proceeds via two competing pathways: the formation of ethyl peroxy radicals (reaction R1) and a chemically activated (or formally direct) HO 2 production (reaction R2). Ethyl peroxy may decompose back to the reactants via reaction R-1…”

Section: Experimental Performancementioning

confidence: 99%

“…Considering the 20% uncertainties on the PI cross sections of ethyl and ethene, our measured yield of C 2 H 4 corresponds to essentially complete conversion of ethyl to ethene, as we expect based on the published C 2 H 5 + O 2 mechanisms. 47,48…”

Section: Experimental Performancementioning

confidence: 99%

Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures

Sheps

Antonov

2019

J. Phys. Chem. A

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We report a new experimental apparatus for direct time-resolved probing of high-pressure gas-phase chemical reactions by photoionization mass spectrometry. The apparatus uses a laser photolysis flow reactor, capable of operating at P = 0.3–100 bar and T = 300–1000 K. We initiate reactions in homogeneous gas mixtures by the photolysis of an appropriate radical precursor using laser pulses at repetition rates of 1–10 Hz. The reacting mixture is continuously sampled into a vacuum chamber, ionized by vacuum-ultraviolet (VUV) photons from laboratory-based discharge lamps or from a synchrotron beamline, and analyzed by a custom mass spectrometer. Soft near-threshold ionization by tunable synchrotron radiation enables spectroscopic quantification of many key intermediates and products of chemical reactions. A novel ionization scheme in the high-density region of the sample jet expansion increases the experimental sensitivity 100-fold, compared with the existing instruments, without compromising mass resolution. A 40 kHz pulsed reflectron time-of-flight mass spectrometer achieves simultaneous detection of all ionized species with 25 μs time resolution. We demonstrate the capability of this apparatus by probing the ethyl radical oxidation reaction using very dilute (<1012 molecules·cm–3) ethyl concentrations at pressures up to 25 bar.

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Forward and reverse uncertainty analyses for RRKM/master equation based kinetic predictions: A case study of ethyl with oxygen

Hou,

Wang,

Yao

et al. 2024

Int J of Chemical Kinetics

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In the realm of combustion kinetic modeling, the norm involves employing thousands of reactions to delineate the chemical conversion of hundreds of species. Notably, theoretically predicted rate coefficients and branching ratios, derived through the RRKM/master equation (ME) model, play an increasing role in kinetic modeling. Thus minimizing the uncertainty of theoretical prediction across wide working conditions is crucial to refine a kinetic model. The present study takes ethyl (C2H5) + oxygen (O2) reaction system to show that combined forward and reverse uncertainty analysis can be used to further constrain calculated rate coefficients and branching ratios, which were already calculated by high‐level quantum chemistry methods. Forward global uncertainty analysis with the artificial neural network‐high dimensional model representation (ANN‐HDMR) method is employed to select key parameters affecting total rate coefficients of C2H5 + O2 and branching ratios of C2H5 + O2 = C2H4 + HO2 (C1). Reverse uncertainty analysis with Bayesian method was then applied to refine the key input parameters based on experimental data at working conditions selected by sensitivity entropy. Although the target RRKM/ME model system was built on high level theoretical calculations, the combined forward and reverse uncertainty analyses are still able to reduce uncertainties of predicted total rate coefficients of C2H5 + O2 and branching ratios for C1 across a wide range of working conditions. Specifically, the uncertainties of total rate coefficient and C1 branching ratio have been reduced from 1.46 and 1.52 to 1.30 and 1.36 at 298 K and 1 Torr. The analysis process proposed in the present work effectively extrapolates the constraint ability of accurate measured data at one condition to wide working conditions based on the RRKM/ME model.

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Experimental and Modeling Study of the Temperature and Pressure Dependence of the Reaction C₂H₅ + O₂ (+ M) → C₂H₅O₂ (+ M)

Cited by 13 publications

References 41 publications

From theoretical reaction dynamics to chemical modeling of combustion

From theoretical reaction dynamics to chemical modeling of combustion

Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures

Forward and reverse uncertainty analyses for RRKM/master equation based kinetic predictions: A case study of ethyl with oxygen

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