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Yang J, Smith MC, Prendergast MB, Chu TC, Green WH. C 14H 10 polycyclic aromatic hydrocarbon formation by acetylene addition to naphthalenyl radicals observed. Phys Chem Chem Phys 2021; 23:14325-14339. [PMID: 34165136 DOI: 10.1039/d1cp01565f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of polycyclic aromatic hydrocarbons (PAHs) during combustion has a substantial impact on environmental pollution and public health. The hydrogen-abstraction-acetylene-addition (HACA) mechanism is expected to be a significant source of larger PAHs containing more than two rings. In this study, the reactions of 1-naphthalenyl and 2-naphthalenyl radicals with acetylene (C2H2) are investigated using VUV photoionization time-of-flight mass spectrometry at 500 to 800 K, 15 to 50 torr, and reaction times up to 10 ms. Our experimental conditions allow us to probe the Bittner-Howard and modified Frenklach HACA routes, but not routes that require multiple radicals to drive the chemistry. The kinetic measurements are compared to a temperature-dependent kinetic model constructed using quantum chemistry calculations and accounting for chemical-activation and fall-off effects. We measure significant quantities of C14H10 (likely phenanthrene and anthracene), as well as 2-ethynylnaphthalene (C12H8), from the reaction of the 2-naphthalenyl radical with C2H2; these results are consistent with the predictions of the kinetic model and the HACA mechanism, but contradict a previous experimental study that indicated no C14H10 formation in the 2-naphthalenyl + C2H2 reaction. In the 1-naphthalenyl radical + C2H2 reaction system, the primary product measured is C12H8, consistent with the predicted formation of acenaphthylene via HACA. The present work provides direct experimental evidence that single-radical HACA can be an important mechanism for the formation of PAHs larger than naphthalene, validating a common assumption in combustion models.
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Affiliation(s)
- Jeehyun Yang
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mica C Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Matthew B Prendergast
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Zaitsau DH, Siewert R, Pimerzin AA, Bülow M, Held C, Loor M, Schulz S, Verevkin SP. From volatility to solubility: Thermodynamics of imidazolium-based ionic liquids containing chloride and bromide anions. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114998] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Chu T, Smith MC, Yang J, Liu M, Green WH. Theoretical study on the HACA chemistry of naphthalenyl radicals and acetylene: The formation of C
12
H
8
, C
14
H
8
, and C
14
H
10
species. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21397] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Te‐Chun Chu
- Department of Chemical Engineering Massachusetts Institute of Technology Cambridge Massachusetts
| | - Mica C. Smith
- Department of Chemical Engineering Massachusetts Institute of Technology Cambridge Massachusetts
| | - Jeehyun Yang
- Department of Earth Atmospheric and Planetary Sciences Massachusetts Institute of Technology Cambridge Massachusetts
| | - Mengjie Liu
- Department of Chemical Engineering Massachusetts Institute of Technology Cambridge Massachusetts
| | - William H. Green
- Department of Chemical Engineering Massachusetts Institute of Technology Cambridge Massachusetts
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Wen Z, Tang X, Fittschen C, Zhang C, Wang T, Wang C, Gu X, Zhang W. Online analysis of gas-phase radical reactions using vacuum ultraviolet lamp photoionization and time-of-flight mass spectrometry. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:043201. [PMID: 32357716 DOI: 10.1063/1.5135387] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
A home-made vacuum ultraviolet photoionization time-of-flight mass spectrometer has been developed and coupled to an atmospheric simulation chamber operated at atmospheric pressure and to a fast flow tube at low pressure (1-10 Torr). Gas sampling from the simulation chamber is realized directly via a capillary effusive beam, and sampling from the flow tube is via a continuous molecular beam inlet. Both devices are connected simultaneously to the ionization chamber of the mass spectrometer and can be switched in-between within minutes to study gas-phase radical reactions of atmospheric interest in a large range of reaction conditions and reaction times (from milliseconds in the flow tube to hours in the simulation chamber). A cage-shaped photoionization source combined with a commercial 10.6 eV krypton lamp has been developed to provide a high ion collection efficiency along the long light path in the cage. This way, a multiplexed detection with high sensitivity down to the sub-parts per billion volume concentration range, e.g., a limit of detection of 0.3 ppbv with an accumulation time of 60 s for benzene and 1.3 ppbv for the methyl radical, is obtained. The performance and suitability of the setup are illustrated by the study of the chlorine-initiated oxidation reaction of toluene in the atmospheric simulation chamber and in the fast flow tube. Stable products and reactive intermediates have been well-determined and their reaction dynamics are discussed.
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Affiliation(s)
- Zuoying Wen
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Xiaofeng Tang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Christa Fittschen
- University Lille, CNRS, UMR 8522, PC2A - Physicochimie des Processus de Combustion et de l'Atmosphère, F-59000 Lille, France
| | - Cuihong Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Tao Wang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Chengcheng Wang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Xuejun Gu
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
| | - Weijun Zhang
- Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei, 230031 Anhui, China
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Chu TC, Buras ZJ, Eyob B, Smith MC, Liu M, Green WH. Direct Kinetics and Product Measurement of Phenyl Radical + Ethylene. J Phys Chem A 2020; 124:2352-2365. [PMID: 32118435 PMCID: PMC7307927 DOI: 10.1021/acs.jpca.9b11543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
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The phenyl + ethylene (C6H5 + C2H4) reaction network was
explored experimentally and theoretically
to understand the temperature dependence of the reaction kinetics
and product distribution under various temperature and pressure conditions.
The flash photolysis apparatus combining laser absorbance spectroscopy
(LAS) and time-resolved molecular beam mass spectrometry (MBMS) was
used to study reactions on the C8H9 potential
energy surface (PES). In LAS experiments, 505.3 nm laser light selectively
probed C6H5 decay, and we measured the total
C6H5 consumption rate coefficients in the intermediate
temperature region (400–800 K), which connects previous experiments
performed in high-temperature (pyrolysis) and low-temperature (cavity-ring-down
methods) regions. From the quantum chemistry calculations by Tokmakov
and Lin using the G2M(RCC5)//B3LYP method, we constructed a kinetic
model and estimated phenomenological pressure-dependent rate coefficients, k(T, P), with the Arkane
package in the reaction mechanism generator. The MBMS experiments,
performed at 600–800 K and 10–50 Torr, revealed three
major product peaks: m/z = 105 (adducts,
mostly 2-phenylethyl radical, but also 1-phenylethyl radical, ortho-ethyl phenyl radical, and a spiro-fused ring radical),
104 (styrene, co-product with a H atom), and 78 (benzene, co-product
with C2H3 radical). Product branching ratios
were predicted by the model and validated by experiments for the first
time. At 600 K and 10 Torr, the yield ratio of the H-abstraction reaction
(forming benzene + C2H3) is measured to be 1.1%
and the H-loss channel (styrene + H) has a 2.5% yield ratio. The model
predicts 1.0% for H-abstraction and 2.3% for H-loss, which is within
the experimental error bars. The branching ratio and formation of
styrene increase at high temperature due to the favored formally direct
channel (1.0% at 600 K and 10 Torr, 5.8% at 800 K and 10 Torr in the
model prediction) and the faster β-scission reactions of C8H9 isomers. The importance of pressure dependence
in kinetics is verified by the increase in the yield of the stabilized
adduct from radical addition from 80.2% (800 K, 10 Torr) to 88.9%
(800 K, 50 Torr), at the expense of styrene + H. The pressure-dependent
model developed in this work is well validated by the LAS and MBMS
measurements and gives a complete picture of the C6H5 + C2H4 reaction.
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Affiliation(s)
- Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Zachary J Buras
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Brook Eyob
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Mica C Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Mengjie Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Smith MC, Liu G, Buras ZJ, Chu TC, Yang J, Green WH. Direct Measurement of Radical-Catalyzed C 6H 6 Formation from Acetylene and Validation of Theoretical Rate Coefficients for C 2H 3 + C 2H 2 and C 4H 5 + C 2H 2 Reactions. J Phys Chem A 2020; 124:2871-2884. [PMID: 32164407 PMCID: PMC7309326 DOI: 10.1021/acs.jpca.0c00558] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
The
addition of vinylic radicals to acetylene is an important step
contributing to the formation of polycyclic aromatic hydrocarbons
in combustion. The overall reaction 3C2H2 →
C6H6 could result in large benzene yields, but
without accurate rate parameters validated by experiment, the extent
of aromatic ring formation from this pathway is uncertain. The addition
of vinyl radicals to acetylene was investigated using time-resolved
photoionization time-of-flight mass spectrometry at 500 and 700 K
and 5–50 Torr. The formation of C6H6 was
observed at all conditions, attributed to sequential addition to acetylene
followed by cyclization. Vinylacetylene (C4H4) was observed with increasing yield from 500 to 700 K, attributed
to the β-scission of the thermalized 1,3-butadien-1-yl radical
and the chemically activated reaction C2H3 +
C2H2 → C4H4 + H.
The measured kinetics and product distributions are consistent with
a kinetic model constructed using pressure- and temperature-dependent
reaction rate coefficients computed from previously reported ab initio calculations. The experiments provide direct measurements
of the hypothesized C4H5 intermediates and validate
predictions of pressure-dependent addition reactions of vinylic radicals
to C2H2, which are thought to play a key role
in soot formation.
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Affiliation(s)
- Mica C Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 01239, United States
| | - Guozhu Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 01239, United States.,Key Laboratory for Green Chemical Technology of the Ministry of Education, School of Chemical Engineering and Technology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, China
| | - Zachary J Buras
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 01239, United States
| | - Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 01239, United States
| | - Jeehyun Yang
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 01239, United States
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 01239, United States
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7
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Sheps L, Antonov I, Au K. Sensitive Mass Spectrometer for Time-Resolved Gas-Phase Chemistry Studies at High Pressures. J Phys Chem A 2019; 123:10804-10814. [DOI: 10.1021/acs.jpca.9b08393] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Leonid Sheps
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Ivan Antonov
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Kendrew Au
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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Chu TC, Buras ZJ, Smith MC, Uwagwu AB, Green WH. From benzene to naphthalene: direct measurement of reactions and intermediates of phenyl radicals and acetylene. Phys Chem Chem Phys 2019; 21:22248-22258. [DOI: 10.1039/c9cp04554f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
First-time measurement of time evolution of the main products and critical intermediates on phenyl HACA pathways with a validated pressure-dependent model.
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Affiliation(s)
- Te-Chun Chu
- Massachusetts Institute of Technology
- Cambridge
- USA
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