1
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Doner AC, Dewey NS, Rotavera B. Unimolecular Reactions of 2-Methyloxetanyl and 2-Methyloxetanylperoxy Radicals. J Phys Chem A 2023; 127:6816-6829. [PMID: 37535464 PMCID: PMC10440797 DOI: 10.1021/acs.jpca.3c03918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/17/2023] [Indexed: 08/05/2023]
Abstract
Alkyl-substituted cyclic ethers are intermediates formed in abundance during the low-temperature oxidation of hydrocarbons and biofuels via a chain-propagating step with ȮH. Subsequent reactions of cyclic ether radicals involve a competition between ring opening and reaction with O2, the latter of which enables pathways mediated by hydroperoxy-substituted carbon-centered radicals (Q̇OOH). Due to the resultant implications of competing unimolecular and bimolecular reactions on overall populations of ȮH, detailed insight into the chemical kinetics of cyclic ethers remains critical to high-fidelity numerical modeling of combustion. Cl-initiated oxidation experiments were conducted on 2-methyloxetane (an intermediate of n-butane oxidation) using multiplexed photoionization mass spectrometry (MPIMS), in tandem with calculations of stationary point energies on potential energy surfaces for unimolecular reactions of 2-methyloxetanyl and 2-methyloxetanylperoxy isomers. The potential energy surfaces were computed using the KinBot algorithm with stationary points calculated at the CCSD(T)-F12/cc-pVDZ-F12 level of theory. The experiments were conducted at 6 Torr and two temperatures (650 K and 800 K) under pseudo-first-order conditions to facilitate Ṙ + O2 reactions. Photoionization spectra were measured from 8.5 eV to 11.0 eV in 50-meV steps, and relative yields were quantified for species consistent with Ṙ → products and Q̇OOH → products. Species detected in the MPIMS experiments are linked to specific radicals of 2-methyloxetane. Species from Ṙ → products include methyl, ethene, formaldehyde, propene, ketene, 1,3-butadiene, and acrolein. Ion signals consistent with products from alkyl radical oxidation were detected, including for Q̇OOH-mediated species, which are also low-lying channels on their respective potential energy surfaces. In addition to species common to alkyl oxidation pathways, ring-opening reactions of Q̇OOH radicals derived from 2-methyloxetane produced ketohydroperoxide species (performic acid and 2-hydroperoxyacetaldehyde), which may impart additional chain-branching potential, and dicarbonyl species (3-oxobutanal and 2-methylpropanedial), which often serve as proxies for modeling reaction rates of ketohydroperoxides. The experimental and computational results underscore that reactions of cyclic ethers are inherently more complex than currently prescribed in chemical kinetic models utilized for combustion.
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Affiliation(s)
- Anna C. Doner
- University
of Georgia, Department of Chemistry, Athens, Georgia 30602, United States
| | - Nicholas S. Dewey
- University
of Georgia, Department of Chemistry, Athens, Georgia 30602, United States
| | - Brandon Rotavera
- University
of Georgia, Department of Chemistry, Athens, Georgia 30602, United States
- University
of Georgia, College of Engineering, Athens, Georgia 30602, United States
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2
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Lahm ME, Bartlett MA, Liang T, Pu L, Allen WD, Schaefer HF. The multichannel i-propyl + O2 reaction system: A model of secondary alkyl radical oxidation. J Chem Phys 2023; 159:024305. [PMID: 37428067 DOI: 10.1063/5.0156705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 06/19/2023] [Indexed: 07/11/2023] Open
Abstract
The i-propyl + O2 reaction mechanism has been investigated by definitive quantum chemical methods to establish this system as a benchmark for the combustion of secondary alkyl radicals. Focal point analyses extrapolating to the ab initio limit were performed based on explicit computations with electron correlation treatments through coupled cluster single, double, triple, and quadruple excitations and basis sets up to cc-pV5Z. The rigorous coupled cluster single, double, and triple excitations/cc-pVTZ level of theory was used to fully optimize all reaction species and transition states, thus, removing some substantial flaws in reference geometries existing in the literature. The vital i-propylperoxy radical (MIN1) and its concerted elimination transition state (TS1) were found 34.8 and 4.4 kcal mol-1 below the reactants, respectively. Two β-hydrogen transfer transition states (TS2, TS2') lie above the reactants by (1.4, 2.5) kcal mol-1 and display large Born-Oppenheimer diagonal corrections indicative of nearby surface crossings. An α-hydrogen transfer transition state (TS5) is discovered 5.7 kcal mol-1 above the reactants that bifurcates into equivalent α-peroxy radical hanging wells (MIN3) prior to a highly exothermic dissociation into acetone + OH. The reverse TS5 → MIN1 intrinsic reaction path also displays fascinating features, including another bifurcation and a conical intersection of potential energy surfaces. An exhaustive conformational search of two hydroperoxypropyl (QOOH) intermediates (MIN2 and MIN3) of the i-propyl + O2 system located nine rotamers within 0.9 kcal mol-1 of the corresponding lowest-energy minima.
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Affiliation(s)
- Mitchell E Lahm
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Marcus A Bartlett
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Tao Liang
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Liang Pu
- College of Chemistry and Pharmacy, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China
| | - Wesley D Allen
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
- Allen Heritage Foundation, Dickson, Tennessee 37055, USA
| | - Henry F Schaefer
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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3
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Doner AC, Zádor J, Rotavera B. Unimolecular Reactions of 2,4-Dimethyloxetanyl Radicals. J Phys Chem A 2023; 127:2591-2600. [PMID: 36898134 PMCID: PMC10041641 DOI: 10.1021/acs.jpca.2c08290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Alkyl-substituted oxetanes are cyclic ethers formed via unimolecular reactions of QOOH radicals produced via a six-membered transition state in the preceding isomerization step of organic peroxy radicals, ROO. Owing to radical isomer-specific formation pathways, cyclic ethers are unambiguous proxies for inferring QOOH reaction rates. Therefore, accounting for subsequent oxidation of cyclic ethers is important in order to accurately determine rates for QOOH → products. Cyclic ethers can react via unimolecular reaction (ring-opening) or via bimolecular reaction with O2 to form cyclic ether-peroxy adducts. The computations herein provide reaction mechanisms and theoretical rate coefficients for the former type in order to determine competing pathways for the cyclic ether radicals. Rate coefficients of unimolecular reactions of 2,4-dimethyloxetanyl radicals were computed using master equation modeling from 0.01 to 100 atm and from 300 to 1000 K. Coupled-cluster methods were utilized for stationary-point energy calculations, and uncertainties in the computed rate coefficients were accounted for using variation in barrier heights and in well depths. The potential energy surfaces reveal accessible channels to several species via crossover reactions, such as 2-methyltetrahydrofuran-5-yl and pentanonyl isomers. For the range of temperature over which 2,4-dimethyloxetane forms during n-pentane oxidation, the following are the major channels: 2,4-dimethyloxetan-1-yl → acetaldehyde + allyl, 2,4-dimethyloxetan-2-yl → propene + acetyl, and 2,4-dimethyloxetan-3-yl → 3-butenal + methyl, or, 1-penten-3-yl-4-ol. Well-skipping reactions were significant in a number of channels and also exhibited a markedly different pressure dependence. The calculations show that rate coefficients for ring-opening are approximately an order of magnitude lower for the tertiary 2,4-dimethyloxetanyl radicals than for the primary and secondary 2,4-dimethyloxetanyl radicals. Unlike for reactions of the corresponding ROO radicals, however, unimolecular rate coefficients are independent of the stereochemistry. Moreover, rate coefficients of cyclic ether radical ring-opening are of the same order of magnitude as O2 addition, underscoring the point that a competing network of reactions is necessary to include for accurate chemical kinetics modeling of species profiles for cyclic ethers.
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Affiliation(s)
| | - Judit Zádor
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, United States
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4
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Popolan‐Vaida DM, Eskola AJ, Rotavera B, Lockyear JF, Wang Z, Sarathy SM, Caravan RL, Zádor J, Sheps L, Lucassen A, Moshammer K, Dagaut P, Osborn DL, Hansen N, Leone SR, Taatjes CA. Formation of Organic Acids and Carbonyl Compounds in
n
‐Butane Oxidation via γ‐Ketohydroperoxide Decomposition. Angew Chem Int Ed Engl 2022; 61:e202209168. [DOI: 10.1002/anie.202209168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Denisia M. Popolan‐Vaida
- Department of Chemistry and Physics University of California, Berkeley Berkeley CA 94720 USA
- Department of Chemistry University of Central Florida Orlando FL 32816 USA
| | - Arkke J. Eskola
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
- Department of Chemistry University of Helsinki 00014 Helsinki Finland
| | - Brandon Rotavera
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
- Department of Chemistry and College of Engineering University of Georgia Athens GA 30602 USA
| | - Jessica F. Lockyear
- Department of Chemistry and Physics University of California, Berkeley Berkeley CA 94720 USA
| | - Zhandong Wang
- King Abdullah University of Science and Technology (KAUST) Clean Combustion Research Center (CCRC) Thuwal 23955-6900 Saudi Arabia
- National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei Anhui 230029 P. R. China
| | - S. Mani Sarathy
- King Abdullah University of Science and Technology (KAUST) Clean Combustion Research Center (CCRC) Thuwal 23955-6900 Saudi Arabia
| | - Rebecca L. Caravan
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
- Chemical Sciences and Engineering Division Argonne National Laboratory Lemont IL 60439 USA
| | - Judit Zádor
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
| | - Leonid Sheps
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
| | - Arnas Lucassen
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
- Physikalisch-Technische Bundesanstalt 38116 Braunschweig Germany
| | - Kai Moshammer
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
- Physikalisch-Technische Bundesanstalt 38116 Braunschweig Germany
| | - Philippe Dagaut
- Centre National de la Recherche Scientifique (CNRS) INSIS ICARE 45071 Orléans Cedex 2 France
| | - David L. Osborn
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
| | - Nils Hansen
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
| | - Stephen R. Leone
- Department of Chemistry and Physics University of California, Berkeley Berkeley CA 94720 USA
| | - Craig A. Taatjes
- Combustion Research Facility Sandia National Laboratories Livermore CA 94551 USA
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5
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Popolan-Vaida DM, Eskola AJ, Rotavera B, Lockyear JF, Wang Z, Sarathy SM, Caravan RL, Zádor J, Sheps L, Lucassen A, Moshammer K, Dagaut P, Osborn DL, Hansen N, Leone SR, Taatjes CA. Formation of Organic Acids and Carbonyl Compounds in n‐Butane Oxidation via γ‐Ketohydroperoxide Decomposition. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Arkke J. Eskola
- University of Helsinki City Centre Campus: Helsingin Yliopisto Chemistry 00014 Helsinki FINLAND
| | | | - Jessica F. Lockyear
- University of California Berkeley College of Chemistry Chemistry 94720 Berkeley UNITED STATES
| | - Zhandong Wang
- University of Science and Technology of China Chemistry 230029 Hefei CHINA
| | - S. Mani Sarathy
- King Abdullah University of Science and Technology Clean Combustion Research Center 23955-6900 Thuwal SAUDI ARABIA
| | - Rebecca L. Caravan
- Argonne National Laboratory Chemical Sciences and Engineering Division 60439 Lemont UNITED STATES
| | - Judit Zádor
- Sandia National Laboratories California Combustion Research Facility 94551 Livermore UNITED STATES
| | - Leonid Sheps
- Sandia National Laboratories California Combustion Research Facility 94551 Livermore UNITED STATES
| | - Arnas Lucassen
- Physikalisch-Technische Bundesanstalt Prevention of Ignition Sources 38116 Braunschweig GERMANY
| | - Kai Moshammer
- Physikalisch-Technische Bundesanstalt Prevention of Ignition Sources 38116 Braunschweig GERMANY
| | - Philippe Dagaut
- Centre National de la Recherche Scientifique INSIS, ICARE 45071 Orléans Cedex FRANCE
| | - David L. Osborn
- Sandia National Laboratories California Combustion Research Facility 94551 Livermore UNITED STATES
| | - Nils Hansen
- Sandia National Laboratories California Combustion Research Facility 94551 Livermore UNITED STATES
| | - Stephen R. Leone
- University of California Berkeley College of Chemistry Chemistry 94720 Berkeley UNITED STATES
| | - Craig A. Taatjes
- Sandia National Laboratories California Combustion Research Facility 94551 Livermore UNITED STATES
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6
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Doner A, Zádor J, Rotavera B. Stereoisomer-dependent unimolecular kinetics of 2,4-dimethyloxetane peroxy radicals. Faraday Discuss 2022; 238:295-319. [DOI: 10.1039/d2fd00029f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2,4,dimethyloxetane is an important cyclic ether intermediate that is produced from hydroperoxyalkyl (QOOH) radicals in low-temperature combustion of n-pentane. However, reaction mechanisms and rates of consumption pathways remain unclear. In...
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7
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Bierkandt T, Oßwald P, Gaiser N, Krüger D, Köhler M, Hoener M, Shaqiri S, Kaczmarek D, Karakaya Y, Hemberger P, Kasper T. Observation of low‐temperature chemistry products in laminar premixed low‐pressure flames by molecular‐beam mass spectrometry. INT J CHEM KINET 2021. [DOI: 10.1002/kin.21503] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Thomas Bierkandt
- German Aerospace Center (DLR) Institute of Combustion Technology Stuttgart Germany
| | - Patrick Oßwald
- German Aerospace Center (DLR) Institute of Combustion Technology Stuttgart Germany
| | - Nina Gaiser
- German Aerospace Center (DLR) Institute of Combustion Technology Stuttgart Germany
| | - Dominik Krüger
- German Aerospace Center (DLR) Institute of Combustion Technology Stuttgart Germany
| | - Markus Köhler
- German Aerospace Center (DLR) Institute of Combustion Technology Stuttgart Germany
| | - Martin Hoener
- Mass Spectrometry in Reactive Flows University of Duisburg‐Essen Duisburg Germany
| | - Shkelqim Shaqiri
- Mass Spectrometry in Reactive Flows University of Duisburg‐Essen Duisburg Germany
| | - Dennis Kaczmarek
- Mass Spectrometry in Reactive Flows University of Duisburg‐Essen Duisburg Germany
| | - Yasin Karakaya
- Mass Spectrometry in Reactive Flows University of Duisburg‐Essen Duisburg Germany
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry Paul Scherrer Institute Villigen Switzerland
| | - Tina Kasper
- Mass Spectrometry in Reactive Flows University of Duisburg‐Essen Duisburg Germany
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8
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Demireva M, Au K, Sheps L. Direct time-resolved detection and quantification of key reactive intermediates in diethyl ether oxidation at T = 450-600 K. Phys Chem Chem Phys 2020; 22:24649-24661. [PMID: 33099590 DOI: 10.1039/d0cp03861j] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-pressure multiplexed photoionization mass spectrometry (MPIMS) with tunable vacuum ultraviolet (VUV) ionization radiation from the Lawrence Berkeley Labs Advanced Light Source is used to investigate the oxidation of diethyl ether (DEE). Kinetics and photoionization (PI) spectra are simultaneously measured for the species formed. Several stable products from DEE oxidation are identified and quantified using reference PI cross-sections. In addition, we directly detect and quantify three key chemical intermediates: peroxy (ROO˙), hydroperoxyalkyl peroxy (˙OOQOOH), and ketohydroperoxide (HOOP[double bond, length as m-dash]O, KHP). These intermediates undergo dissociative ionization (DI) into smaller fragments, making their identification by mass spectrometry challenging. With the aid of quantum chemical calculations, we identify the DI channels of these key chemical species and quantify their time-resolved concentrations from the overall carbon atom balance at T = 450 K and P = 7500 torr. This allows the determination of the absolute PI cross-sections of ROO˙, ˙OOQOOH, and KHP into each DI channel directly from experiment. The PI cross-sections in turn enable the quantification of ROO˙, ˙OOQOOH, and KHP from DEE oxidation over a range of experimental conditions that reveal the effects of pressure, O2 concentration, and temperature on the competition among radical decomposition and second O2 addition pathways.
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Affiliation(s)
- Maria Demireva
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
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9
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Doner AC, Davis MM, Koritzke AL, Christianson MG, Turney JM, Schaefer HF, Sheps L, Osborn DL, Taatjes CA, Rotavera B. Isomer‐dependent reaction mechanisms of cyclic ether intermediates:cis‐2,3‐dimethyloxirane andtrans‐2,3‐dimethyloxirane. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21429] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Anna C. Doner
- Department of Chemistry University of Georgia Athens GA USA
| | - Matthew M. Davis
- Department of Chemistry University of Georgia Athens GA USA
- Center for Computational Quantum Chemistry University of Georgia Athens GA USA
| | | | | | - Justin M. Turney
- Center for Computational Quantum Chemistry University of Georgia Athens GA USA
| | - Henry F. Schaefer
- Department of Chemistry University of Georgia Athens GA USA
- Center for Computational Quantum Chemistry University of Georgia Athens GA USA
| | - Leonid Sheps
- Combustion Research Facility Sandia National Laboratories Livermore CA USA
| | - David L. Osborn
- Combustion Research Facility Sandia National Laboratories Livermore CA USA
| | - Craig A. Taatjes
- Combustion Research Facility Sandia National Laboratories Livermore CA USA
| | - Brandon Rotavera
- Department of Chemistry University of Georgia Athens GA USA
- College of Engineering University of Georgia Athens GA USA
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10
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Christianson MG, Doner AC, Davis MM, Koritzke AL, Turney JM, Schaefer HF, Sheps L, Osborn DL, Taatjes CA, Rotavera B. Reaction mechanisms of a cyclic ether intermediate: Ethyloxirane. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21423] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Anna C. Doner
- Department of Chemistry University of Georgia Athens Georgia
| | - Matthew M. Davis
- Department of Chemistry University of Georgia Athens Georgia
- Center for Computational Quantum Chemistry University of Georgia Athens Georgia
| | | | - Justin M. Turney
- Center for Computational Quantum Chemistry University of Georgia Athens Georgia
| | - Henry F. Schaefer
- Department of Chemistry University of Georgia Athens Georgia
- Center for Computational Quantum Chemistry University of Georgia Athens Georgia
| | - Leonid Sheps
- Combustion Research Facility Sandia National Laboratories Livermore California
| | - David L. Osborn
- Combustion Research Facility Sandia National Laboratories Livermore California
| | - Craig A. Taatjes
- Combustion Research Facility Sandia National Laboratories Livermore California
| | - Brandon Rotavera
- Department of Chemistry University of Georgia Athens Georgia
- College of Engineering University of Georgia Athens Georgia
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11
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McDermott WP, Venegas J, Hermans I. Selective Oxidative Cracking of n-Butane to Light Olefins over Hexagonal Boron Nitride with Limited Formation of CO x. CHEMSUSCHEM 2020; 13:152-158. [PMID: 31424599 DOI: 10.1002/cssc.201901663] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 08/04/2019] [Indexed: 06/10/2023]
Abstract
In recent years, hexagonal boron nitride (hBN) has emerged as an unexpected catalyst for the oxidative dehydrogenation of alkanes. Here, the versatility of hBN was extended to alkane oxidative cracking chemistry by investigating the production of ethylene and propylene from n-butane. Cracking selectivity was primarily controlled by the ratio of n-butane to O2 within the reactant feed. Under O2 -lean conditions, increasing temperature led to increased selectivity to ethylene and propylene and decreased selectivity to COx . In addition to surface-mediated chemistry, homogeneous gas-phase reactions likely contributed to the observed product distribution, and a reaction mechanism was proposed based on these observations. The catalyst showed good stability under oxidative cracking conditions for 100 h time-on-stream while maintaining high selectivity to ethylene and propylene.
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Affiliation(s)
- William P McDermott
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA
| | - Juan Venegas
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA
| | - Ive Hermans
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI, 53706, USA
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA
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12
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Davis JC, Koritzke AL, Caravan RL, Antonov IO, Christianson MG, Doner AC, Osborn DL, Sheps L, Taatjes CA, Rotavera B. Influence of the Ether Functional Group on Ketohydroperoxide Formation in Cyclic Hydrocarbons: Tetrahydropyran and Cyclohexane. J Phys Chem A 2019; 123:3634-3646. [PMID: 30865470 DOI: 10.1021/acs.jpca.8b12510] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photolytically initiated oxidation experiments were conducted on cyclohexane and tetrahydropyran using multiplexed photoionization mass spectrometry to assess the impact of the ether functional group in the latter species on reaction mechanisms relevant to autoignition. Pseudo-first-order conditions, with [O2]0:[R•]0 > 2000, were used to ensure that R• + O2 → products were the dominant reactions. Quasi-continuous, tunable vacuum ultraviolet light from a synchrotron was employed over the range 8.0-11.0 eV to measure photoionization spectra of the products at two pressures (10 and 1520 Torr) and three temperatures (500, 600, and 700 K). Photoionization spectra of ketohydroperoxides were measured in both species and were qualitatively identical, within the limit of experimental noise, to those of analogous species formed in n-butane oxidation. However, differences were noted in the temperature dependence of ketohydroperoxide formation between the two species. Whereas the yield from cyclohexane is evident up to 700 K, ketohydroperoxides in tetrahydropyran were not detected above 650 K. The difference indicates that reaction mechanisms change due to the ether group, likely affecting the requisite •QOOH + O2 addition step. Branching fractions of nine species from tetrahydropyran were quantified with the objective of determining the role of ring-opening reactions in diminishing ketohydroperoxide. The results indicate that products formed from unimolecular decomposition of R• and •QOOH radicals via concerted C-C and C-O β-scission are pronounced in tetrahydropyran and are insignificant in cyclohexane oxidation. The main conclusion drawn is that, under the conditions herein, ring-opening pathways reduce the already low steady-state concentration of •QOOH, which in the case of tetrahydropyran prevents •QOOH + O2 reactions necessary for ketohydroperoxide formation. Carbon balance calculations reveal that products from ring opening of both R• and •QOOH, at 700 K, account for >70% at 10 Torr and >55% at 1520 Torr. Three pathways are confirmed to contribute to the depletion of •QOOH in tetrahydropyran including (i) γ-•QOOH → pentanedial + •OH, (ii) γ-•QOOH → vinyl formate + ethene + •OH, and (iii) γ-•QOOH → 3-butenal + formaldehyde + •OH. Analogous mechanisms in cyclohexane oxidation leading to similar intermediates are compared and, on the basis of mass spectral results, confirm that no such ring-opening reactions occur. The implication from the comparison to cyclohexane is that the ether group in tetrahydropyran increases the propensity for ring-opening reactions and inhibits the formation of ketohydroperoxide isomers that precede chain-branching. On the contrary, the absence of such reactions in cyclohexane enables ketohydroperoxide formation up to 700 K and perhaps higher temperature.
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Affiliation(s)
| | | | - Rebecca L Caravan
- Combustion Research Facility , Sandia National Laboratories , Livermore , California 94551 , United States
| | - Ivan O Antonov
- Combustion Research Facility , Sandia National Laboratories , Livermore , California 94551 , United States
| | | | | | - David L Osborn
- Combustion Research Facility , Sandia National Laboratories , Livermore , California 94551 , United States
| | - Leonid Sheps
- Combustion Research Facility , Sandia National Laboratories , Livermore , California 94551 , United States
| | - Craig A Taatjes
- Combustion Research Facility , Sandia National Laboratories , Livermore , California 94551 , United States
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13
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Bartlett MA, Liang T, Pu L, Schaefer HF, Allen WD. The multichannel n-propyl + O2 reaction surface: Definitive theory on a model hydrocarbon oxidation mechanism. J Chem Phys 2018. [DOI: 10.1063/1.5017305] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Marcus A. Bartlett
- Center for Computational Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Tao Liang
- Center for Computational Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Liang Pu
- College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shaanxi 712100, People’s Republic of China
| | - Henry F. Schaefer
- Center for Computational Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Wesley D. Allen
- Center for Computational Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, USA
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14
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Kaiser EW, Wallington TJ. Products from the Oxidation of n-Butane from 298 to 735 K Using Either Cl Atom or Thermal Initiation: Formation of Acetone and Acetic Acid-Possible Roaming Reactions? J Phys Chem A 2017; 121:8543-8560. [PMID: 28982240 DOI: 10.1021/acs.jpca.7b06608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The oxidation of 2-butyl radicals (and to a lesser extent 1-butyl radicals) has been studied over the temperature range of 298-735 K. The reaction of Cl atoms (formed by 360 nm irradiation of Cl2) with n-butane generated the 2-butyl radicals in mixtures of n-C4H10, O2, and Cl2 at temperatures below 600 K. Above 600 K, 2-butyl radicals were produced by thermal combustion reactions in the absence of chlorine. The yields of the products were measured by gas chromatography using a flame ionization detector. Major products quantified include acetone, acetic acid, acetaldehyde, butanone, 2-butanol, butanal, 1- and 2- chlorobutane, 1-butene, trans-2-butene, and cis-2-butene. At 298 K, the major oxygenated products are those expected from bimolecular reactions of 2-butylperoxy radicals (butanone, 2-butanol, and acetaldehyde). As the temperature rises to 390 K, the butanone decreases while acetaldehyde increases because of the increased rate of 2-butoxy radical decomposition. Acetone and acetic acid first appear in significant yield near 400 K, and these species rise slowly at first and then sharply, peaking near 525 K at yields of ∼25 and ∼20 mol %, respectively. In the same temperature range (400-525 K), butanone, acetaldehyde, and 2-butanol decrease rapidly. This suggests that acetone and acetic acid may be formed by previously unknown reaction channels of the 2-butylperoxy radical, which are in competition with those that lead to butanone, acetaldehyde, and 2-butanol. Above 570 K, the yields of acetone and acetic acid fall rapidly as the yields of the butenes rise. Experiments varying the Cl atom density, which in turn controls the entire radical pool density, were performed in the temperature range of 410-440 K. Decreasing the Cl atom density increased the yields of acetone and acetic acid while the yields of butanone, acetaldehyde, and 2-butanol decreased. This is consistent with the formation of acetone and acetic acid by unimolecular decomposition channels of the 2-butylperoxy radical, which are in competition with the bimolecular channels that form butanone, acetaldehyde, and 2-butanol. Such unimolecular decomposition channels would be unlikely to proceed through conventional transition states because those states would be very constrained. Therefore, the possibility that these decomposition channels proceed via roaming should be considered. In addition, we investigated and were unable to fit our data trends by a simplified ketohydroperoxide mechanism.
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Affiliation(s)
- E W Kaiser
- Department of Natural Sciences, University of Michigan-Dearborn , 4901 Evergreen Road, Dearborn, Michigan 48128, United States
| | - T J Wallington
- Research and Advanced Engineering, Ford Motor Company , Dearborn, Michigan 48121-2053, United States
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15
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Eskola AJ, Antonov IO, Sheps L, Savee JD, Osborn DL, Taatjes CA. Time-resolved measurements of product formation in the low-temperature (550-675 K) oxidation of neopentane: a probe to investigate chain-branching mechanism. Phys Chem Chem Phys 2017; 19:13731-13745. [PMID: 28503692 DOI: 10.1039/c7cp01366c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Product formation, in particular ketohydroperoxide formation and decomposition, were investigated in time-resolved, Cl-atom initiated neopentane oxidation experiments in the temperature range 550-675 K using a photoionization time-of-flight mass spectrometer. Ionization light was provided either by Advanced Light Source tunable synchrotron radiation or ∼10.2 eV fixed energy radiation from a H2-discharge lamp. Experiments were performed both at 1-2 atm pressure using a high-pressure reactor and also at ∼9 Torr pressure employing a low-pressure reactor for comparison. Because of the highly symmetric structure of neopentane, ketohydroperoxide signal can be attributed to a 3-hydroperoxy-2,2-dimethylpropanal isomer, i.e. from a γ-ketohydroperoxide (γ-KHP). The photoionization spectra of the γ-KHP measured at low- and high pressures and varying oxygen concentrations agree well with each other, further supporting they originate from the single isomer. Measurements performed in this work also suggest that the "Korcek" mechanism may play an important role in the decomposition of 3-hydroperoxy-2,2-dimethylpropanal, especially at lower temperatures. However, at higher temperatures where γ-KHP decomposition to hydroxyl radical and oxy-radical dominates, oxidation of the oxy-radical yields a new important channel leading to acetone, carbon monoxide, and OH radical. Starting from the initial neopentyl + O2 reaction, this channel releases altogether three OH radicals. A strongly temperature-dependent reaction product is observed at m/z = 100, likely attributable to 2,2-dimethylpropanedial.
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Affiliation(s)
- Arkke J Eskola
- Combustion Research Facility, Sandia National Laboratories, 7011 East Avenue, MS 9055, Livermore, California 94551, USA.
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16
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Osborn DL. Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry. Annu Rev Phys Chem 2017; 68:233-260. [DOI: 10.1146/annurev-physchem-040215-112151] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David L. Osborn
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550
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17
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Scheer AM, Eskola AJ, Osborn DL, Sheps L, Taatjes CA. Resonance Stabilization Effects on Ketone Autoxidation: Isomer-Specific Cyclic Ether and Ketohydroperoxide Formation in the Low-Temperature (400–625 K) Oxidation of Diethyl Ketone. J Phys Chem A 2016; 120:8625-8636. [DOI: 10.1021/acs.jpca.6b07370] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Adam M. Scheer
- Combustion Research Facility, Sandia National Laboratories, MS 9055, Livermore, California 94551, United States
| | - Arkke J. Eskola
- Combustion Research Facility, Sandia National Laboratories, MS 9055, Livermore, California 94551, United States
| | - David L. Osborn
- Combustion Research Facility, Sandia National Laboratories, MS 9055, Livermore, California 94551, United States
| | - Leonid Sheps
- Combustion Research Facility, Sandia National Laboratories, MS 9055, Livermore, California 94551, United States
| | - Craig A. Taatjes
- Combustion Research Facility, Sandia National Laboratories, MS 9055, Livermore, California 94551, United States
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18
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Antonov IO, Zádor J, Rotavera B, Papajak E, Osborn DL, Taatjes CA, Sheps L. Pressure-Dependent Competition among Reaction Pathways from First- and Second-O2 Additions in the Low-Temperature Oxidation of Tetrahydrofuran. J Phys Chem A 2016; 120:6582-95. [DOI: 10.1021/acs.jpca.6b05411] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ivan O. Antonov
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Judit Zádor
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Brandon Rotavera
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Ewa Papajak
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - David L. Osborn
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Craig A. Taatjes
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Leonid Sheps
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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19
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Tsolas N, Lee JG, Yetter RA. Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0344. [PMID: 26170423 DOI: 10.1098/rsta.2014.0344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/06/2015] [Indexed: 06/04/2023]
Abstract
The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems.
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Affiliation(s)
- Nicholas Tsolas
- Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Jong Guen Lee
- Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Richard A Yetter
- Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802, USA
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20
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Welz O, Burke MP, Antonov IO, Goldsmith CF, Savee JD, Osborn DL, Taatjes CA, Klippenstein SJ, Sheps L. New Insights into Low-Temperature Oxidation of Propane from Synchrotron Photoionization Mass Spectrometry and Multiscale Informatics Modeling. J Phys Chem A 2015; 119:7116-29. [DOI: 10.1021/acs.jpca.5b01008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Oliver Welz
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Michael P. Burke
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60493, United States
- Department
of Mechanical Engineering, Department of Chemical Engineering and
Data Sciences Institute, Columbia University, New York, New York 10027, United States
| | - Ivan O. Antonov
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - C. Franklin Goldsmith
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60493, United States
| | - John D. Savee
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - David L. Osborn
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Craig A. Taatjes
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Stephen J. Klippenstein
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60493, United States
| | - Leonid Sheps
- Combustion
Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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21
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Herbinet O, Battin-Leclerc F. Progress in Understanding Low-Temperature Organic Compound Oxidation Using a Jet-Stirred Reactor. INT J CHEM KINET 2014. [DOI: 10.1002/kin.20871] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Olivier Herbinet
- Laboratoire Réactions et Génie des Procédés; Université de Lorraine; CNRS, ENSIC, BP 20451 54000 Nancy France
| | - Frédérique Battin-Leclerc
- Laboratoire Réactions et Génie des Procédés; Université de Lorraine; CNRS, ENSIC, BP 20451 54000 Nancy France
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22
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Wang Z, Herbinet O, Cheng Z, Husson B, Fournet R, Qi F, Battin-Leclerc F. Experimental investigation of the low temperature oxidation of the five isomers of hexane. J Phys Chem A 2014; 118:5573-94. [PMID: 25007100 DOI: 10.1021/jp503772h] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The low-temperature oxidation of the five hexane isomers (n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethylbutane, and 2,3-dimethylbutane) was studied in a jet-stirred reactor (JSR) at atmospheric pressure under stoichiometric conditions between 550 and 1000 K. The evolution of reactant and product mole fraction profiles were recorded as a function of the temperature using two analytical methods: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Experimental data obtained with both methods were in good agreement for the five fuels. These data were used to compare the reactivity and the nature of the reaction products and their distribution. At low temperature (below 800 K), n-hexane was the most reactive isomer. The two methyl-pentane isomers have about the same reactivity, which was lower than that of n-hexane. 2,2-Dimethylbutane was less reactive than the two methyl-pentane isomers, and 2,3-dimethylbutane was the least reactive isomer. These observations are in good agreement with research octane numbers given in the literature. Cyclic ethers with rings including 3, 4, 5, and 6 atoms have been identified and quantified for the five fuels. While the cyclic ether distribution was notably more detailed than in other literature of JSR studies of branched alkane oxidation, some oxiranes were missing among the cyclic ethers expected from methyl-pentanes. Using SVUV-PIMS, the formation of C2-C3 monocarboxylic acids, ketohydroperoxides, and species with two carbonyl groups have also been observed, supporting their possible formation from branched reactants. This is in line with what was previously experimentally demonstrated from linear fuels. Possible structures and ways of decomposition of the most probable ketohydroperoxides were discussed. Above 800 K, all five isomers have about the same reactivity, with a larger formation from branched alkanes of some unsaturated species, such as allene and propyne, which are known to be soot precursors.
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Affiliation(s)
- Zhandong Wang
- Laboratoire Réactions et Génie des Procédés, CNRS - Université de Lorraine, BP 20451, 1 rue Grandville, 54000 Nancy, France
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