Isomer-Selective Detection of Keto-Hydroperoxides in the Low-Temperature Oxidation of Tetrahydrofuran

Hansen, Nils; Moshammer, Kai; Jasper, Ahren W.

doi:10.1021/acs.jpca.9b07017

Title: Isomer-Selective Detection of Keto-Hydroperoxides in the Low-Temperature Oxidation of Tetrahydrofuran

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Abstract

Keto-hydroperoxides (KHPs) are reactive, partially oxidized intermediates that play a central role in chain-branching reactions during the gas-phase low-temperature oxidation of hydrocarbons and oxygenated species. Although multiple isomeric forms of the KHP intermediate are possible in complex oxidation environments when multiple reactant radicals exist that contain nonequivalent O-2 addition sites, isomer-resolved data of KHPs have not been reported. In this work, we provide partially isomer-resolved detection and quantification of the KHPs that form during the low-temperature oxidation of tetrahydrofuran (THF, cycl.-O-CH2CH2CH2CH2). We describe how these short-lived KHPs were detected, identified, and quantified using integrated experimental and theoretical approaches. The experimental approaches were based on direct molecular-beam sampling from a jet-stirred reactor operated at near-atmospheric pressure and at temperatures between 500 and 700 K, followed by mass spectrometry with single-photon ionization via tunable synchrotron-generated vacuum-ultraviolet radiation, and the identification of fragmentation patterns. The interpretation of the experiments was guided by theoretical calculations of ionization thresholds, fragment appearance energies, and photoionization cross sections. On the basis of the experimentally observed and theoretically calculated ionization and fragment appearance energies, KHP isomers could be distinguished as originating from H-abstraction reactions from either the alpha-C adjacent to the O atom or the beta-C atoms. Temperature-dependentmore »« less

Authors:

^[1]; Moshammer, Kai ^[2];

^[3]

Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)
Argonne National Lab. (ANL), Lemont, IL (United States)

Publication Date:: Wed Sep 04 00:00:00 EDT 2019

Research Org.:: Sandia National Lab. (SNL-CA), Livermore, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division

OSTI Identifier:: 1570293

Alternate Identifier(s):: OSTI ID: 1574362

Report Number(s):: SAND-2019-10051J
Journal ID: ISSN 1089-5639; 678832; TRN: US2001319

Grant/Contract Number:: AC04-94AL85000; AC02-06CH11357

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

Additional Journal Information:: Journal Volume: 123; Journal Issue: 38; Journal ID: ISSN 1089-5639

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats


                    Hansen, Nils, Moshammer, Kai, and Jasper, Ahren W. Isomer-Selective Detection of Keto-Hydroperoxides in the Low-Temperature Oxidation of Tetrahydrofuran.  United States: N. p., 2019. 
Web.  doi:10.1021/acs.jpca.9b07017.

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                    Hansen, Nils, Moshammer, Kai, & Jasper, Ahren W. Isomer-Selective Detection of Keto-Hydroperoxides in the Low-Temperature Oxidation of Tetrahydrofuran.  United States.  https://doi.org/10.1021/acs.jpca.9b07017

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                    Hansen, Nils, Moshammer, Kai, and Jasper, Ahren W. Wed .  
"Isomer-Selective Detection of Keto-Hydroperoxides in the Low-Temperature Oxidation of Tetrahydrofuran".  United States.  https://doi.org/10.1021/acs.jpca.9b07017.  https://www.osti.gov/servlets/purl/1570293.

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@article{osti_1570293,

  title        = {Isomer-Selective Detection of Keto-Hydroperoxides in the Low-Temperature Oxidation of Tetrahydrofuran},

  author       = {Hansen, Nils and Moshammer, Kai and Jasper, Ahren W.},

  abstractNote = {Keto-hydroperoxides (KHPs) are reactive, partially oxidized intermediates that play a central role in chain-branching reactions during the gas-phase low-temperature oxidation of hydrocarbons and oxygenated species. Although multiple isomeric forms of the KHP intermediate are possible in complex oxidation environments when multiple reactant radicals exist that contain nonequivalent O-2 addition sites, isomer-resolved data of KHPs have not been reported. In this work, we provide partially isomer-resolved detection and quantification of the KHPs that form during the low-temperature oxidation of tetrahydrofuran (THF, cycl.-O-CH2CH2CH2CH2). We describe how these short-lived KHPs were detected, identified, and quantified using integrated experimental and theoretical approaches. The experimental approaches were based on direct molecular-beam sampling from a jet-stirred reactor operated at near-atmospheric pressure and at temperatures between 500 and 700 K, followed by mass spectrometry with single-photon ionization via tunable synchrotron-generated vacuum-ultraviolet radiation, and the identification of fragmentation patterns. The interpretation of the experiments was guided by theoretical calculations of ionization thresholds, fragment appearance energies, and photoionization cross sections. On the basis of the experimentally observed and theoretically calculated ionization and fragment appearance energies, KHP isomers could be distinguished as originating from H-abstraction reactions from either the alpha-C adjacent to the O atom or the beta-C atoms. Temperature-dependent concentration profiles of the partially resolved isomeric KHP intermediates were determined in the range of 500-700 K, and the results indicate that the observed KHP isomers are formed overwhelmingly (similar to 99%) from the alpha-C THF radical. Comparisons of the partially isomer-resolved quantification of the KHPs to up-to-date kinetic modeling results reveal new opportunities for the development of a next-generation THF oxidation mechanism.},

  doi          = {10.1021/acs.jpca.9b07017},

  journal      = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},

  number       = 38,

  volume       = 123,

  place        = {United States},

  year         = {Wed Sep 04 00:00:00 EDT 2019},

  month        = {Wed Sep 04 00:00:00 EDT 2019}

}

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