Shock-tube studies of Sarin surrogates

Mathieu, Olivier; Kulatilaka, Waruna D.; Petersen, Eric L.

doi:10.1007/s00193-018-0841-1

Cited by 12 publications

(11 citation statements)

References 24 publications

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“…The proposed kinetic model was used to predict OH time-histories during TEP combustion at conditions reported by Mathieu et al 26 The simulated OH profiles showed a two-stage ignition behavior (Figure 8). However, no such behavior was reported by Mathieu et al 26 To calculate ignition delay time using the proposed kinetic model, we used the corresponding peak and maximum slope of predicted OH time-histories as shown in Figure 8. As seen in Figure 9a, predicted ignition delay time for the rich TEP mixture (φ = 2) is in very good agreement with the experiment data.…”

Section: Resultsmentioning

confidence: 97%

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Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)

et al. 2019

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Triethyl phosphate (TEP) is an organophosphorus compound used as a simulant for highly toxic nerve agents such as sarin GB. A high temperature decomposition pathway during TEP pyrolysis has been proposed previously and takes place via seven concerted elimination reactions. A computational study to investigate the kinetics of these seven reactions was carried out at the CBS-QB3 level of theory. The transition state optimization was done at the B3LYP/6-311G(2d,d,p) theory level, and CanTherm was used to derive the Arrhenius coefficients. The pre-exponential factors of the rate constant of these reactions were found to be up to 50 times lower than the estimated values from the literature. In addition, kinetics of reaction of the trioxidophosphorus radical (PO 3 ) with H 2 (H 2 + PO 3 → HOPO 2 + H), which is one of the important reactions in predicting CO formation during TEP decomposition, was also investigated computationally at the same theory level. The new kinetic parameters derived from the computational study were used with the TEP kinetic model proposed recently by our group. In addition, an alternative decomposition pathway for TEP decomposition via H-abstraction, radical decomposition, and recombination reactions was added. The proposed mechanism was validated with the literature's experimental data, that is, intermediate CO time-history data from pyrolysis and oxidation experiments and ignition delay times. Fairly good agreement with experiments was obtained for pyrolysis and oxidation CO yield within 1200−1700 K. The model was able to predict the ignition times of the rich TEP mixture (φ = 2) within 25% of the experimental results, while the discrepancies for stoichiometric and rich mixtures were larger. Discussions on results of sensitivity and reaction pathway analysis are presented to identify the important phosphorus reactions and to understand the effect of addition of the alternative TEP decomposition pathway.

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Section: Resultsmentioning

confidence: 97%

“…In addition, the new TEP chemical kinetic model is compared with data from Mathieu et al, 26 who recently published shock tube ignition delay times for TEP combustion within 1100 to 2100 K and near 1.5 atm. The experiments were conducted at three equivalence ratios: 0.5, 1, and 2.…”

Section: Methodsmentioning

confidence: 99%

Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)

et al. 2019

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“…Phosphine (PH 3 ) is a toxic and pyrophoric gas that is used as a phosphorus source in the semiconductor industry , and as a fumigant in the agricultural industry . A recent focus on phosphorous chemistry has arisen out of an interest in organophosphorus compounds (OPCs), which can serve as both fire suppressants and surrogates for chemical weapons of mass destruction such as Sarin . Although PH 3 is not an OPC, its small size and correspondingly simple chemistry may make it suitable as a foundation for more-complex phosphorous chemistry and as a precursor for various phosphorus-containing intermediates.…”

Section: Introductionmentioning

confidence: 99%

A Shock-Tube Study of the Rate Constant of PH₃ + M ⇄ PH₂ + H + M (M = Ar) Using PH₃ Laser Absorption

et al. 2020

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Phosphine (PH 3 ) is a highly reactive and toxic gas. Prior experimental investigations of PH 3 pyrolysis reactions have included only low-temperature measurements. This study reports the first shock-tube measurements of PH 3 pyrolysis using a new PH 3 laser absorption technique near 4.56 μm. Experiments were conducted in mixtures of 0.5% PH 3 / Ar behind reflected shock waves at temperatures of 1460−2013 K and pressures of ∼1.3 and ∼0.5 atm. The PH 3 time histories displayed two-stage behavior similar to that previously observed for NH 3 decomposition, suggesting by analogy that the rate constant for PH 3 + M ⇄ PH 2 + H + M (R1) could be determined. A simple three-step mechanism was assembled for data analysis. In a detailed kinetic analysis of the first-stage PH 3 decomposition, values of k 1,0 were obtained and best described by (in cm 3 •mol −1 •s −1 ) k 1,0 = 7.78 × 10 17 exp(−80,400/ RT), with units of cal, mol, K, s, and cm 3 . Agreement between the 1.3 and 0.5 atm data confirmed that the measured k 1,0 was in the low-pressure limit. Agreement of the experimental k 1,0 with ab initio estimates resolved the question of the main pathway of PH 3 decomposition: it proceeds as PH 3 ⇄ PH 2 + H instead of PH 3 ⇄ PH + H 2 .

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“…In our study, we obtained free energy values of 62.75 to 5.24 kJ/mol within the 200–1000 °C temperature range. Recent experiments on CWAs have also been carried out under similar temperatures, including vapor-phase decomposition of DMMP (a sarin surrogate) at 500–800 K, sarin decomposition on TiO 2 nanoparticles at 1000 K, and decomposition of CWAs at 2000 K. ,, Collectively, all of these experiments showed that the temperature ranges studied in this work can also be achieved under operational conditions, and DIMP would decompose on the γ-Al 2 O 3 surface. Due to the structural similarity between DIMP and sarin, our calculations provide additional insight into decomposition mechanisms of both these molecules and elucidate atomic details of sarin decomposition on candidate metal oxide surfaces.…”

Section: Discussionmentioning

confidence: 67%

High-Temperature Decomposition of Diisopropyl Methylphosphonate on Alumina: Mechanistic Predictions from Ab Initio Molecular Dynamics

Biswas

Wong

2021

J. Phys. Chem. C

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The enhanced degradation of organophosphorousbased chemical warfare agents (CWAs) on metal oxide surfaces holds immense promise for neutralization efforts; however, the underlying mechanisms in this process remain poorly understood. For the first time, we utilize large-scale quantum calculations to probe the high-temperature degradation of diisopropyl methylphosphonate (DIMP), a nerve agent simulant. Our Born− Oppenheimer molecular dynamics (BOMD) calculations show that the γ-Al 2 O 3 surface shows immense promise for quickly adsorbing and destroying CWAs. We find that the alumina surface quickly adsorbs DIMP at all temperatures, and subsequent decomposition of DIMP proceeds via a propene elimination. Our BOMD calculations are complemented with metadynamics simulations to produce free energy paths, which show that the activation barrier decreases with temperature and that DIMP readily decomposes on γ-Al 2 O 3 . Our first-principle BOMD and metadynamics simulations provide crucial diagnostics for sarin decomposition models and mechanistic information for examining CWA decomposition reactions on other candidate metal oxide surfaces.

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Shock-tube studies of Sarin surrogates

Cited by 12 publications

References 24 publications

Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)

Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)

A Shock-Tube Study of the Rate Constant of PH₃ + M ⇄ PH₂ + H + M (M = Ar) Using PH₃ Laser Absorption

High-Temperature Decomposition of Diisopropyl Methylphosphonate on Alumina: Mechanistic Predictions from Ab Initio Molecular Dynamics

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Shock-tube studies of Sarin surrogates

Cited by 12 publications

References 24 publications

Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)

Theoretical Calculation of Reaction Rates and Combustion Kinetic Modeling Study of Triethyl Phosphate (TEP)

A Shock-Tube Study of the Rate Constant of PH3 + M ⇄ PH2 + H + M (M = Ar) Using PH3 Laser Absorption

High-Temperature Decomposition of Diisopropyl Methylphosphonate on Alumina: Mechanistic Predictions from Ab Initio Molecular Dynamics

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A Shock-Tube Study of the Rate Constant of PH₃ + M ⇄ PH₂ + H + M (M = Ar) Using PH₃ Laser Absorption