New experiments and validated master-equation modeling for OH production in propyl+O2 reactions

Huang, Haifeng; Merthe, Daniel J.; Zádor, Judit; Jusinski, Leonard E.; Taatjes, Craig A.

doi:10.1016/j.proci.2010.06.039

Cited by 38 publications

(103 citation statements)

References 29 publications

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“…The set of optimized theoretical kinetics parameters, rate parameters, and physical model parameters from the present analysis using the targets from Tables 1−3 yield final values and predictions in reasonable consistency with ab initio calculations, 59 rate constant measurements, 86,87 and global measurements and experimental conditions (refs 26, 44, 45, 50, and 61 and present work) used as targets (with all |Y t,i − F i (X j,opt )| < Z i ). In particular, as shown below, the multiscale informed model is consistent with earlier time-resolved measurements of OH at 10 Torr 26 as well as the present time-resolved measurements of OH at 30 Torr and recent MPIMS measurements of methyloxirane at 4 Torr, 61 for which modeling based on previous interpretations 26 and recent theoretical kinetics calculations 59 are inconsistent with experimental observations.…”

Section: Results With Multiscale Informedsupporting

confidence: 87%

“…Unlike previous modeling, where barrier heights for TS3 and TS11 of the R + O 2 reaction surfaces were considered to be the predominant source of uncertainty in modeling the OH profiles, 26 the present analysis shows that rigorous interpretation of the OH measurements requires consideration of many additional model aspectsincluding uncertainties in barrier 594 K following pulsed photolysis to produce Cl. The 10 largest contributors to uncertainty in peak OH shown in part a constitute 90% of the total a priori model variance; the 6 largest contributors to uncertainty in peak OH shown in part b constitute 90% of the total a priori model variance.…”

Section: Resultsmentioning

confidence: 67%

“…Figure 8 shows comparisons of various species time profiles measured using MPIMS in (COCl) 2 /C 3 H 8 /O 2 /He mixtures at 4 Torr at 530 and 670 K following pulsed photolysis to produce Cl, 61 predictions using the rate constants derived in Huang et al, 26 and predictions using the a priori and multiscale informed models. ( Figure S7 in the Supporting Information shows comparisons for 600 K, and our companion paper 61 shows comparisons for all species at all temperatures.)…”

Section: Results With Multiscale Informedmentioning

confidence: 99%

“…Previously, Huang et al 26 concluded that R + O 2 ↔ OH + methyloxirane was responsible for OH production at their experimental conditions of 10 Torr and 426−698 K. They adjusted the barrier heights for rate-limiting transition states to form OH + methyloxirane (TS3 and TS11, following the nomenclature of Goldsmith et al, 59 cf. Figure 1 and Table 1) to match their measured OH time profiles.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, the multiscale informed model results identify an unexpected role of QOOH + O 2 reactions and potential non-Boltzmann reaction sequences in interpretations of these earlier OH measurements. 26 …”

Section: Introductionmentioning

confidence: 99%

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Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

et al. 2015

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The present paper describes further development of the multiscale informatics approach to kinetic model formulation of Burke et al. (Burke, M. P.; Klippenstein, S. J.; Harding, L. B. Proc. Combust. Inst. 2013, 34, 547-555) that directly incorporates elementary kinetic theories as a means to provide reliable, physics-based extrapolation of kinetic models to unexplored conditions. Here, we extend and generalize the multiscale informatics strategy to treat systems of considerable complexity-involving multiwell reactions, potentially missing reactions, nonstatistical product branching ratios, and non-Boltzmann (i.e., nonthermal) reactant distributions. The methodology is demonstrated here for a subsystem of low-temperature propane oxidation, as a representative system for low-temperature fuel oxidation. A multiscale model is assembled and informed by a wide variety of targets that include ab initio calculations of molecular properties, rate constant measurements of isolated reactions, and complex systems measurements. Active model parameters are chosen to accommodate both "parametric" and "structural" uncertainties. Theoretical parameters (e.g., barrier heights) are included as active model parameters to account for parametric uncertainties in the theoretical treatment; experimental parameters (e.g., initial temperatures) are included to account for parametric uncertainties in the physical models of the experiments. RMG software is used to assess potential structural uncertainties due to missing reactions. Additionally, branching ratios among product channels are included as active model parameters to account for structural uncertainties related to difficulties in modeling sequences of multiple chemically activated steps. The approach is demonstrated here for interpreting time-resolved measurements of OH, HO2, n-propyl, i-propyl, propene, oxetane, and methyloxirane from photolysis-initiated low-temperature oxidation of propane at pressures from 4 to 60 Torr and temperatures from 300 to 700 K. In particular, the multiscale informed model provides a consistent quantitative explanation of both ab initio calculations and time-resolved species measurements. The present results show that interpretations of OH measurements are significantly more complicated than previously thought-in addition to barrier heights for key transition states considered previously, OH profiles also depend on additional theoretical parameters for R + O2 reactions, secondary reactions, QOOH + O2 reactions, and treatment of non-Boltzmann reaction sequences. Extraction of physically rigorous information from those measurements may require more sophisticated treatment of all of those model aspects, as well as additional experimental data under more conditions, to discriminate among possible interpretations and ensure model reliability.

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Section: Results With Multiscale Informedsupporting

confidence: 87%

Section: Resultsmentioning

confidence: 67%

Section: Results With Multiscale Informedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

et al. 2015

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Computational Treatments of Peroxy Radicals in Combustion and Atmospheric Reactions

Kuwata¹

2014

Patai's Chemistry of Functional Groups

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I. INTRODUCTIONPeroxy species are key intermediates in chemical reactions in both combustion 1, 2 and the troposphere 3,4 , which is the layer of the atmosphere extending from the Earth's surface to roughly 15 km in altitude, where temperature stops decreasing with altitude 5 . As is true for the study of reactive intermediates in general, advances in the understanding of peroxides have come from a dialog between theory-both electronic structure and statistical rate theory calculations-and experiment. This chapter focuses on the insights that electronic structure calculations, particularly those involving composite methods and density functional theory (DFT), have brought to peroxide chemistry. As much as possible, experimental results will be cited to validate or challenge the predictions of electronic structure theory. (While a direct comparison between electronic structure predictions and experimental data sometimes requires applications of statistical rate theory and other 1

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Anharmonic Effect of N‐Propyl Peroxy Dissociation

Pan

et al. 2016

J Chinese Chemical Soc

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The anharmonic and harmonic dissociation rate constants of alkylperoxy (RO2) in different pathways, as well as those for the reactions of the n‐propyl peroxy radical, were calculated using the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. When the temperature/total energy increased, the rate constants of the different pathways varied independently, causing changes in the dominating/leading products. Anharmonic rate constants were larger than harmonic rate constants, and their difference increased with increasing temperature/energy. Therefore, the anharmonic effect cannot be neglected. The rate‐determining steps of CH3CH2CH2OO dissociation are discussed. Then the anharmonic effect was found clearly for CH3CH2CH2OO dissociation, especially for the hydroperoxyalkyl radical (QOOH) dissociation. At low temperature, the rate constants were similar to those found from experiment, which indicated the RRKM theory was suitable for calculating the dissociation rates of RO2 species.

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New experiments and validated master-equation modeling for OH production in propyl+O2 reactions

Cited by 38 publications

References 29 publications

Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

Computational Treatments of Peroxy Radicals in Combustion and Atmospheric Reactions

Anharmonic Effect of N‐Propyl Peroxy Dissociation

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