Combined Experimental and Computational Study on the Unimolecular Decomposition of JP-8 Jet Fuel Surrogates. II: n-Dodecane (n-C12H26)

Zhao, Long; Yang, Tao; Kaiser, Ralf I.; Troy, Tyler P.; Ahmed, Musahid; Ribeiro, João Marcelo Lamim; Belisario-Lara, Daniel; Mebel, Alexander M.

doi:10.1021/acs.jpca.6b11817

Cited by 30 publications

(19 citation statements)

References 98 publications

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“…The detailed methodology is introduced in our previous works. 70,71 Briefly, the PIE curves were fitted by a linear combination of known PIE reference curves from an online PIE database 72 . Since the ion count normalized by the photon fluxes holds a direct proportional relationship with the mole fraction (concentration), the photoionization cross section, mass discrimination ( ( , ) ∝ ( ) • ( ) • ), 50, 57, 68, 69 and the ion counts measured in the experiment, the branching ratios between the concentrations of individual products can be calculated via (…”

Section: Discussionmentioning

confidence: 99%

A vacuum ultraviolet photoionization study on high-temperature decomposition of JP-10 (exo-tetrahydrodicyclopentadiene)

Zhao

Yang

Kaiser

et al. 2017

Phys. Chem. Chem. Phys.

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121

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Two sets of experiments were performed to unravel the high-temperature pyrolysis of tricyclo[5.2.1.0 2,6 ] decane (JP-10) exploiting high-temperature reactors over a temperature range of 1100 K to 1600 K Advanced Light Source (ALS) and 927 K to 1083 K National Synchrotron Radiation Laboratory (NSRL)with residence times of a few tens of microseconds (ALS) to typically 144 ms (NSRL). The products were identified in situ in supersonic molecular beams via single photon vacuum ultraviolet (VUV) photoionization coupled with mass spectroscopic detection in a reflectron time-of-flight mass spectrometer (ReTOF). These studies were designed to probe the initial (ALS) and also higher order reaction products (NSRL) formed in the decomposition of JP-10 -including radicals and thermally labile closed-shell species. Altogether 43 products were detected and quantified including C1-C4 alkenes, dienes, C3-C4 cumulenes, alkynes, eneynes, diynes, cycloalkenes, cyclo-dienes, aromatic molecules, and most important, radicals such as ethyl, allyl, and methyl produced at lower residence times. At longer residence times, the predominant fragments are molecular hydrogen (H2), ethylene (C2H4), propene (C3H6), cyclopentadiene (C5H6), cyclopentene (C5H8), fulvene (C6H6), and benzene (C6H6).Accompanied by electronic structure calculations, the initial JP-10 decomposition via C-H bond cleavages resulting in the formation of initially six C10H15 radicals were found to explain the formation of all products detected in both sets of experiments. These radicals are not stable under the experiment conditions and further decompose via C-C bond -scission processes. These pathways result in ring opening in the initial tricyclic carbon skeletons of JP-10. Intermediates accessed after the first -scission can further isomerize or dissociate. Complex PAH products in the NRLS experiment (naphthalene, acenaphthylene, biphenyl) are likely formed via molecular growth reactions at elevated residence times.3

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Section: Discussionmentioning

confidence: 99%

A vacuum ultraviolet photoionization study on high-temperature decomposition of JP-10 (exo-tetrahydrodicyclopentadiene)

Zhao

Yang

Kaiser

et al. 2017

Phys. Chem. Chem. Phys.

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121

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“…Three organic species, toluene, n-dodecane, and β-caryophyllene, were selected to represent atmospheric SOA precursors from anthropogenic and biogenic sources (Table S1). Toluene and n-dodecane are often selected as surrogate jet fuel components to investigate combustion and emission characteristics because they have been proven well-suited to represent tens of hundreds of components found in mainstream jet fuels (e.g., Dooley et al, 2010;Dooley et al, 2012;Zhang et al, 2016;Zhao et al, 2017). Field aircraft emission studies also confirm the presence of these unburnt aliphatic and aromatic organic compounds in aircraft engine exhaust (e.g., Beyersdorf et al, 2012;Kinsey et al, 2011;Pison and Menut, 2004; https://doi.org/10.5194/acp-2020-809 Preprint.…”

Section: Soa Coating Materialsmentioning

confidence: 99%

The effects of morphology, mobility size and SOA material coating on the ice nucleation activity of black carbon in the cirrus regime

Zhang¹,

Zhang²,

Wolf³

et al. 2020

Preprint

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Abstract. There is evidence that black carbon (BC) particles may affect cirrus formation and hence global climate by acting as potential ice nucleating particles (INPs) in the troposphere. Nevertheless, the ice nucleation (IN) ability of bare BC and BC coated with secondary organic aerosol (SOA) material remains uncertain. We have systematically examined the IN ability of 100–400 nm size-selected BC particles with different morphologies and different SOA coatings representative of anthropogenic (toluene and n-dodecane) and biogenic (β-caryophyllene) sources in the cirrus regime (−46 to −38 °C). Several aerosolized BC proxies were selected to represent different particle morphologies and oxidation levels. Atmospheric aging was further replicated with exposure of SOA-coated BC to OH. The results demonstrate that the 400 nm hydrophobic BC types nucleate ice only at or near the homogeneous freezing threshold (−42 to −46 ˚C). Deposition IN, as opposed to purely homogeneous freezing, was observed to occur for some BC types between 100–200 nm within the investigated temperature range. More fractal BC particles did not consistently act as superior deposition INPs over more spherical ones. SOA coating generated by oxidizing β-caryophyllene with O3 did not seem to affect BC IN ability. However, SOA coatings generated from OH oxidation of various organic species did exhibit higher IN onset supersaturation ratio with respect to ice (SSi) compared with bare BC particles, with toluene SOA coating showing an increase of SSi by 0.1–0.15 while still below the homogeneous threshold. n-dodecane and β-caryophyllene-derived SOA only froze in the homogeneous regime. We attribute the inhibition of IN ability to the filling of the pores on the BC surface by the SOA material coating. OH exposure levels of all SOA coating experiments, from an equivalent atmospheric 10 days to 90 days, did not render significant differences in IN potential. Our study suggests that BC particles with large sizes and/or oxidized surfaces generally exhibit better IN ability, and that the organic coating materials can inhibit ice formation.

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“…(2) The thermal decomposition of the fuel is not rate limiting and can be treated without needing to know the details at the level of elementary reactions. (3) The number of decomposition products needed to describe subsequent oxidation processes is small as compared to the number of molecules in the original multicomponent fuel. Following this approach, we have recently performed combined experimental and theoretical studies of pyrolysis of a number of important constituents of jet fuels including large alkanes (decane 2 and dodecane 3 ), butylbenzene isomers, 4 and tricyclo[5.2.1.0(2.6)]decane (exo-tetrahydrodicyclopentadiene; exo-TCD; JP-10; C 10 H 16 ).…”

Section: Introductionmentioning

confidence: 99%

“…(3) The number of decomposition products needed to describe subsequent oxidation processes is small as compared to the number of molecules in the original multicomponent fuel. Following this approach, we have recently performed combined experimental and theoretical studies of pyrolysis of a number of important constituents of jet fuels including large alkanes (decane 2 and dodecane 3 ), butylbenzene isomers, 4 and tricyclo[5.2.1.0(2.6)]decane (exo-tetrahydrodicyclopentadiene; exo-TCD; JP-10; C 10 H 16 ). 5,6 These works allowed us to identify the prevailing pyrolysis products for these molecular species and to quantify their relative yields depending on temperature and pressure.…”

Section: Introductionmentioning

confidence: 99%

“…5,6 These works allowed us to identify the prevailing pyrolysis products for these molecular species and to quantify their relative yields depending on temperature and pressure. For instance, for decane and dodecane, 2,3 the detected products included molecular hydrogen, C2-C7 1-alkenes from ethylene to 1-heptene, C1-C3 radicals (methyl, vinyl, ethyl, propargyl, allyl), small C1-C3 hydrocarbons (methane, acetylene, allene and propyne), as well as 1,3-butadiene and 2-butene. For JP-10 decomposition, we identified a broader range of species including alkenes, dienes, cumulenes, alkynes, eneynes, diynes, cycloalkenes, cyclodienes, aromatic molecules, and radicals such as ethyl, propargyl, allyl, cyclopentadienyl, and methyl with about 33% C1-C2, 45% C3-C5, and 22% C6-C8 species at a typical combustion temperature of 1400 K. 5,6 Whereas the oxidation mechanisms of smaller (C1-C2) [7][8][9][10][11][12][13][14][15][16] and larger (C6-C8) hydrocarbons [17][18][19][20][21][22][23] are reasonably well established, the underlying reactivity of the main classes of decomposition products of the products-unsaturated C3-C5 hydrocarbons together with their radicals-is scarcely known.…”

Section: Introductionmentioning

confidence: 99%

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Direct H abstraction by molecular oxygen from unsaturated C3–C5 hydrocarbons: A theoretical study

Alarcon

Mebel

2021

Int J of Chemical Kinetics

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Potential energy surfaces for the H abstraction reactions by molecular oxygen from unsaturated closed-shell C3-C5 hydrocarbons, including allene and propyne (C 3 H 4 ), propene (C 3 H 6 ), diacetylene (C 4 H 2 ), vinylacetylene (C 4 H 4 ), 1,3-butadiene (C 4 H 6 ), butene isomers (C 4 H 8 ), cyclopentadiene (C 5 H 6 ), and cyclopentene (C 5 H 8 ), which were earlier identified among the main pyrolysis products of jet fuel components, have been explored at the CCSD(T)-F12/cc-pVTZ-f12//ωB97XD/6-311G** + ZPE(ωB97XD/6-311G**) level of electronic structure theory. The results of the ab initio calculations were then utilized in transition state theory calculations of the reaction rate constants. The H abstraction reactions by O 2 appeared to be most favorable from the allylic sites and from allene and propyne forming the propargyl radical, with the reactions involving the cyclic allylic sites in cyclopentadiene and cyclopentene exhibiting the lowest reaction endothermicities and barriers. They are followed by the reaction of O 2 with cyclopentene producing cyclopent-1-en-4-yl and the reactions with vinylacetylene and 1,3-butadiene forming the resonantly stabilized i-C 4 H 3 and i-C 4 H 5 radical products. The H abstractions from primary and secondary vinylic sites as well as from acetylenic sites are significantly less favorable and unlikely to compete. The calculated rate constants have been validated against the previous experimental and theoretical results for propene and butene isomers. All considered reactions of H abstraction by O 2 are predicted to be rather slow, with their rate constants at 1500 K being on the order of 10 -17 -10 -16 cm 3 molecule -1 s -1 and exhibiting a well-defined Arrhenius behavior. Modified Arrhenius expressions for the reaction rate constants both in forward and reverse directions and Evans-Polanyi relationship between the activation and reaction energies have been generated and proposed for kinetic combustion models. The H abstractions by O 2 forming the resonantly stabilized radicals were concluded to likely contribute to the initiation of oxidation of the unsaturated C3-C5 species produced in the pyrolysis of the important components of jet fuels.

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Combined Experimental and Computational Study on the Unimolecular Decomposition of JP-8 Jet Fuel Surrogates. II: n-Dodecane (n-C₁₂H₂₆)

Cited by 30 publications

References 98 publications

A vacuum ultraviolet photoionization study on high-temperature decomposition of JP-10 (exo-tetrahydrodicyclopentadiene)

A vacuum ultraviolet photoionization study on high-temperature decomposition of JP-10 (exo-tetrahydrodicyclopentadiene)

The effects of morphology, mobility size and SOA material coating on the ice nucleation activity of black carbon in the cirrus regime

Direct H abstraction by molecular oxygen from unsaturated C3–C5 hydrocarbons: A theoretical study

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