Reactive molecular dynamics simulation on thermal decomposition of n-heptane and methylcyclohexane initiated by nitroethane

Guan, Yulei; Lou, Junpeng; Liu, Ru; Ma, Hua; Song, Jirong

doi:10.1016/j.fuel.2019.116447

Cited by 24 publications

(12 citation statements)

References 54 publications

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“…First, we derived the decomposition rate constant k at each temperature by recording the number of intact PFPE molecules as a function of time, N t , and fitting it with where t is the time and N 0 is the number of intact PFPE molecules at t = 0. It should be noted that the first-order kinetics is assumed in eq , which is reasonable for the thermal decomposition of covalent compounds. ,,, Then, we fitted the reaction decomposition rate constants k at different temperatures T with the Arrhenius equation , where A is a pre-exponential factor, E a is the activation energy, and k B is the Boltzmann constant. As a result, we are able to determine the values of A and E a from the intercept and slope of the fitted line and extrapolate the fitted line to derive decomposition rate constants k at any temperatures of interest.…”

Section: Resultsmentioning

confidence: 99%

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ReaxFF Reactive Molecular Dynamics Simulations of Mechano-Chemical Decomposition of Perfluoropolyether Lubricants in Heat-Assisted Magnetic Recording

et al. 2020

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A thorough understanding of the decomposition of perfluoropolyether (PFPE) lubricants is crucial to achieve heat-assisted magnetic recording (HAMR). In contrast to previous studies, which focused on thermal and catalytic decompositions, we gain insights into the mechano-chemical decomposition of PFPE films confined between the head and disk by performing reactive molecular dynamics simulations with our new ReaxFF force field. By quantifying the decomposition time constants under the operation conditions of HAMR, we infer that, within a heating time of ∼1 ns, pure thermal decomposition hardly occurs, whereas mechano-chemical decomposition is highly likely to occur. The decomposition rate constant of the PFPE films subjected to confined shear increases with normal pressure. The increase is well-fitted by a linear stress-activated Arrhenius curve at high normal pressures, whereas this is not the case at low normal pressures. We caution against extrapolating the linear stress-activated Arrhenius curve, which could cause significant overestimation of decomposition rate constants at low normal pressures. We find that the mechano-chemical decomposition of PFPEs is mainly attributed to the dissociation of C–OH and ether C–O bonds in the polar end groups, and in the main chain, the C–O bond is more likely to dissociate than the C–C bond.

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Section: Resultsmentioning

confidence: 99%

“…It should be noted that the first-order kinetics is assumed in eq 3, which is reasonable for the thermal decomposition of covalent compounds. 29,30,37,63 Then, we fitted the reaction decomposition rate constants k at different temperatures T with the Arrhenius equation 30,64…”

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confidence: 99%

ReaxFF Reactive Molecular Dynamics Simulations of Mechano-Chemical Decomposition of Perfluoropolyether Lubricants in Heat-Assisted Magnetic Recording

et al. 2020

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“…94 Close energetics for the main initial reaction channels in pyrolysis of n-heptane, methylcyclohexane, and nitroethane (the second last one) were reported between the ReaxFF NVT-MD simulations and QM calculations at the M062X/MG3S and CCSD(T)/6-311++g(2df,2p)//M062X/ MG3S levels, where most of the relative errors for energies are below 5%, and the maximum does not exceed 12%. 95 Reasonable agreements of the BDEs of C−C bond fissions between ReaxFF and DFT were reported in thermal decomposition of p-menthane (PMT), a promising "drop-in" fuel of a bioderived isoprenoid hydrocarbon. 96 A comprehensive validation strategy was proposed recently by Kwon et al 9 for evaluating the thermal decomposition reactivity of head-tohead (HtH) bicyclic alkane fuel molecules derived from upgrading bio-oil.…”

Section: Theory and Methodology Progress Of Reaxff MD Simulationsmentioning

confidence: 99%

“…Reaction energies predicted by ReaxFF are usually compared to those of QM by minimizing the structure geometry of the various intermediates taken from the ReaxFF MD trajectory . Close energetics for the main initial reaction channels in pyrolysis of n -heptane, methylcyclohexane, and nitroethane (the second last one) were reported between the ReaxFF NVT-MD simulations and QM calculations at the M062X/MG3S and CCSD(T)/6-311++g(2df,2p)//M062X/MG3S levels, where most of the relative errors for energies are below 5%, and the maximum does not exceed 12% . Reasonable agreements of the BDEs of C–C bond fissions between ReaxFF and DFT were reported in thermal decomposition of p -menthane (PMT), a promising “drop-in” fuel of a bioderived isoprenoid hydrocarbon .…”

Section: Theory and Methodology Progress Of Reaxff MD Simulationsmentioning

confidence: 99%

ReaxFF Molecular Dynamics Simulations of Thermal Reactivity of Various Fuels in Pyrolysis and Combustion

Ren

et al. 2021

Energy Fuels

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The methodology development and applications of ReaxFF molecular dynamics (ReaxFF MD) in unraveling the complex reactions and kinetics for pyrolysis and oxidation of organic systems are reviewed. Particular attention is given to the large-scale ReaxFF MD simulation method of ∼10,000 atoms and practical simulation strategies to overcome the temporal−spatial limits as much as possible. High-performance computing codes running on CPU cluster/supercomputers and on GPU were overviewed. GPU-enabled code like GMD-Reax is revolutionizing large-scale ReaxFF MD simulations to run mainly on a single GPU. A step-forward for reaction analysis was achieved in the code of VARxMD to reveal detailed reactions based on the identification of bond types and unique species that allows for categorization of reaction species and pathways through structure searching of reaction sites and reactants/products. Efforts for extracting rate constants and kinetics modeling from unperturbed kinetics of ReaxFF MD simulations are reviewed, and challenges remain. The important factors of model scale effects, elevated simulation temperature, and possible validation of ReaxFF MD reaction simulation results theoretically and experimentally are illustrated and discussed. The novel hybrid simulation strategies proposed recently that may expand applications of ReaxFF MD to connect with realistic scenarios of engine combustion and relevant chemical effects on aerospace vehicle materials are briefed. The simulation practices of large-scale ReaxFF MD in understanding the similarities and differences of reactivity and reaction mechanisms in pyrolysis of liquid hydrocarbon fuels, solid fuels (coal, biomass, polymer), and energetic materials of CL-20 and its cocrystals are briefly described, which indicates that large-scale ReaxFF MD simulations are a feasible and straight means to capture the dynamics of an almost entire reaction process and to evaluate reactivity of organic systems computationally. There is still a great deal of work to be done to push the boundaries of ReaxFF MD simulations forward. With the constant improvement of the ReaxFF force field and reaction analysis capability, ReaxFF MD playing a key role in understanding reaction mechanisms and its potential in kinetics modeling of pyrolysis and oxidation of various fuels can be expected.

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“…Cyclohexane and its derivatives are widely used in many aviation kerosene model substitutes 45,46 . Naphthenes have received extensive attention due to their high content in practical fuels and some works have been done on the pyrolysis of naphthenes pyrolysis [47][48][49][50][51][52] and combustion 53 .…”

Section: Pyrolysis and Combustion Mechanism Of Naphthenic Hydrocarbon...mentioning

confidence: 99%

Recent ReaxFF MD studies on pyrolysis and combustion mechanisms of aviation/aerospace fuels and energetic additives

Chen

Li²,

Zhang

et al. 2023

Energy Adv.

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Reactive molecular dynamics simulation on thermal decomposition of n-heptane and methylcyclohexane initiated by nitroethane

Cited by 24 publications

References 54 publications

ReaxFF Reactive Molecular Dynamics Simulations of Mechano-Chemical Decomposition of Perfluoropolyether Lubricants in Heat-Assisted Magnetic Recording

ReaxFF Reactive Molecular Dynamics Simulations of Mechano-Chemical Decomposition of Perfluoropolyether Lubricants in Heat-Assisted Magnetic Recording

ReaxFF Molecular Dynamics Simulations of Thermal Reactivity of Various Fuels in Pyrolysis and Combustion

Recent ReaxFF MD studies on pyrolysis and combustion mechanisms of aviation/aerospace fuels and energetic additives

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