An ignition delay time and chemical kinetic modeling study of the pentane isomers

Bugler, John; Marks, Brandon; Mathieu, Olivier; Archuleta, Rachel; Camou, Alejandro; Grégoire, Claire M.; Heufer, Karl Alexander; Petersen, Eric L.; Curran, Henry J.

doi:10.1016/j.combustflame.2015.09.014

Cited by 198 publications

(184 citation statements)

References 33 publications

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“…All rate coefficients are compared on a per H-atom basis. There is good agreement between the literature values, most being within a factor of 2-3 of one another, with a maximum discrepancy of approximately a factor of 5 for reactions proceeding through an 8-membered transition state (TS) ring at 1000 K. As will be shown in an accompanying paper, 19 when applied to the mechanisms of the pentane isomers the rate coefficients for the H-shift reactions of R ̇2 ⇌ ̇O OH through 6-membered TS rings are the most important, with a relatively high flux proceeding through these pathways. Figure 8 shows the effect of using the rate coefficients for the first isomerisation reactions calculated from each of the three studies on the simulated ignition delay times of each of the pentane isomers, as well as treating the second isomerisation reactions as recommended by Curran et al 2,3 .…”

Section: R ̇2 and ̇2 Qooh Isomerisation Reactionssupporting

confidence: 70%

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Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

et al. 2015

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This paper describes our developing understanding of low-temperature oxidation kinetics. We have investigated the ignition of the three pentane isomers in a rapid compression machine over a wide range of temperatures and pressures, including conditions of negative temperature coefficient behavior. The pentane isomers are small alkanes, yet have structures that are complex enough to allow for the application of their kinetic and thermochemical rules to larger molecules. Updates to the thermochemistry of the species important in the low-temperature oxidation of hydrocarbons have been made based on a thorough literature review. An evaluation of recent quantum-chemically derived rate coefficients from the literature pertinent to important low-temperature oxidation reaction classes has been performed, and new rate rules are recommended for these classes. Several reaction classes have also been included to determine their importance with regard to simulation results, and we have found that they should be included when developing future chemical kinetic mechanisms. A comparison of the model simulations with pressure-time histories from experiments in a rapid compression machine shows very good agreement for both ignition delay time and pressure rise for both the firstand second-stage ignition events. We show that revisions to both the thermochemistry and the kinetics are required in order to replicate experiments well. A broader validation of the models with ignition delay times from shock tubes and a rapid compression machine is presented in an accompanying paper. The results of this study enhance our understanding of the combustion of straight-and branched-chained alkanes.

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Section: R ̇2 and ̇2 Qooh Isomerisation Reactionssupporting

confidence: 70%

“…19 This study provides a systematic evaluation of the rate rules in the literature and their suitability for application to mechanisms for the low-temperature oxidation of straight-chained, branched-chained and highlybranched alkanes, and will propose new rate rule recommendations for application to larger alkanes.…”

Section: Introductionmentioning

confidence: 99%

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

et al. 2015

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“…The activation energies of these allyl pentenyl hydroperoxide decomposition reactions are assumed in the present model to be 42.5 kcal/mol, similar to comparable reactions in oxidation of linear alkenes 26 and for alkyl hydroperoxide and ketohydroperoxide species decomposition reactions that break the same type of O-O bond 26,36,50,51 . At temperatures below that needed for the allylic pentenyl hydroperoxide species to decompose rapidly, these combination reactions provide "temporary" chain termination and degenerate chain branching.…”

Section: Low-and Intermediate Temperature Jsr Experiments Simulationsmentioning

confidence: 99%

“…This reaction path is the largest source of both acetone and acetaldehyde in our simulations of 2M2B oxidation. 50,51 . Either of these species can react directly back to fuel + HO 2 , but some can react via cyclization to produce 2,2,3-trimethyl oxirane, as shown in Fig.…”

Section: Reactions Specific To 2-methyl 2-butene Fuelmentioning

confidence: 99%

“…Our past kinetic models 2,36,[49][50][51][52][53][54] , primarily for alkane hydrocarbon fuels, included simplified mechanisms for linear and branched C 5 and other olefins, so the present work required a considerable development of the kinetic mechanism for branched pentene isomers. The core C 1 -C 4 mechanism is the Aramco Mech1.3 55 developed at the National University of substantially to the present work, and application of the EXGAS mechanism development software with its recent upgrades specifically to address olefin mechanisms 28 by Glaude et al 56 helped considerably at identifying the important reaction pathways for 2M2B.…”

Section: Chemical Kinetic Reaction Mechanismmentioning

confidence: 99%

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Experimental and Kinetic Modeling Study of 2-Methyl-2-Butene: Allylic Hydrocarbon Kinetics

et al. 2015

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Two experimental studies have been carried out on the oxidation of 2-methyl-2-butene, one measuring ignition delay times behind reflected shock waves in a stainless steel shock tube, and the other measuring fuel, intermediate, and product species mole fractions in a jet-stirred reactor (JSR) . The shock tube ignition experiments were carried out at three different pressures, approximately 1.7 atm, 11.2 atm, and 31 atm, and at each pressure, fuel-lean =0.5), stoichiometric (=1.0), and fuel-rich (=2.0) mixtures were examined, with each fuel/oxygen mixture diluted in 99% Ar, for initial post-shock temperatures between 1330 and 1730K. The JSR experiments were performed at nearly-atmospheric pressure (800 Torr), with stoichiometric fuel/oxygen mixtures with 0.01 mole fraction of 2M2B fuel, a residence time in the reactor of 1.5s, and mole fractions of 36 different chemical species were measured over a temperature range from 600 to 1150K. These JSR experiments represent the first such studies reporting detailed 2 species measurements for an unsaturated, branched hydrocarbon fuel larger than iso-butene. A detailed chemical kinetic reaction mechanism was developed to study the important reaction pathways in these experiments, with particular attention on the role played by allylic C-H bonds and allylic pentenyl radicals. The results show that, at high temperatures, this olefinic fuel reacts rapidly, similar to related alkane fuels, but the pronounced thermal stability of the allylic pentenyl species inhibits low temperature reactivity, so 2M2B does not produce "cool flames" or negative temperature coefficient behavior. The connections between olefin hydrocarbon fuels, resulting allylic fuel radicals, the resulting lack of low temperature reactivity, and the gasoline engine concept of Octane Sensitivity are discussed.

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Effects of surface species and homogeneous reactions on rates and selectivity in ethane oxidation on oxide catalysts

et al. 2021

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Selective alkane oxidations on metal oxide catalysts involve complex mechanisms with multiple reactions in series and parallel, different types of reduced and oxidized surface species, and potential contributions from gas‐phase reactions. Here, kinetics and thermodynamics of elementary steps involved in C2H6‐O2 reactions on SiO2‐supported small vanadium oxide domains are determined using density functional theory. These surface reactions together with gas‐phase mechanisms are incorporated in kinetic simulations to determine how surface and gaseous reactions interact and contribute to rates and selectivity. The results show that gas‐phase reactions within pore volumes in contact with the catalyst contribute significantly to C2H6 activation rates, even at conditions where gas‐phase reactions in empty volumes without catalyst are negligible. The majority of C2H6 activations occur on the surface, via H abstraction by vanadium oxo species present at terminal lattice oxygens. The gas‐phase activations via H‐abstraction by OH radicals also exhibit significant contributions. The reduced centers formed by reactions at vanadium oxo species are re‐oxidized rapidly and, therefore, are present in very small concentrations at reaction conditions. The re‐oxidation steps lead to the formation of HO2 radicals and surface peroxo species that are also rapidly consumed and are present in small concentrations. The peroxo species preferentially convert C2H4 to its epoxide product and influence selectivity even at low concentrations. The gas‐phase reactions decrease the concentrations of peroxo species and improve selectivity slightly. The effects of reaction conditions and catalyst site density provide further insights into how factors beyond conversions at lattice oxygens influence rates and selectivity in alkane oxidation reactions of significant industrial importance.

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An ignition delay time and chemical kinetic modeling study of the pentane isomers

Abstract: Ignition delay times of n-pentane, iso-pentane, and neo-pentane mixtures were measured in two shock tubes and in a rapid compression machine. The experimental data were used as validation targets for the model described in detail in an accompanying study [

Cited by 198 publications

References 33 publications

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

Revisiting the Kinetics and Thermodynamics of the Low-Temperature Oxidation Pathways of Alkanes: A Case Study of the Three Pentane Isomers

Experimental and Kinetic Modeling Study of 2-Methyl-2-Butene: Allylic Hydrocarbon Kinetics

Effects of surface species and homogeneous reactions on rates and selectivity in ethane oxidation on oxide catalysts

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