First Study of the Pyrolysis of a Halogenated Ester: Methyl Chloroacetate

Abstract

The pyrolysis of a halogenated ester, methyl chloroacetate (MC), under dilute atmosphere and quasiatmospheric pressure was studied at temperatures from 473 to 1048 K using an alumina tubular reactor. MC was chosen as a surrogate to model the thermal decomposition of ethyl bromoacetate, a chemical warfare agent. A maximum MC conversion of 99.8% was observed at a residence time of 2 s, a temperature of 1048 K, and an inlet mole fraction of 0.01. The following products were quantified: CO, CO2, HCl, methane, ethylene, ethane, propene, chloromethane, dichloromethane, vinyl chloride, chloroethane, and dichloroethane. For the first time, a detailed kinetic model of MC pyrolysis was developed and gave a good prediction of the global reactivity and the formation of most of the major products. Flow rate and sensitivity analyses were made to highlight the different pathways of decomposition during the MC pyrolysis. In a first attempt to extrapolate the results obtained with methyl chloroacetate to ethyl bromoacetate, simulations were run with a modified version of the model developed in this study taking into account the differences in bond dissociation energies induced by the change of the chlorine atom by a bromine one. Supplementary MaterialKinetic mechanism used in this work given under CHEMKIN format.Thermodynamic data of all species of the mechanism.Scheme of the experimental setup used for running pyrolysis experiments, measured temperature profile in the TR in absence of reaction, and the carbon, oxygen, and chlorine balances, SCF energy, zero-point corrected electronic energy, frequencies and geometry of molecules, radicals and transition states, calculated at the CBS-QB3 level of theory, comparison of the kinetic parameters of reaction R30 in Table 1 with literature data, experimental mole fractions of species in a tabular form.

Kinetic Investigation of the Pyrolysis of Isobutyric Anhydride and Isobutyric Acid

“…The conformers corresponding to the lowest energy of 3 kJ/mol were recalculated at the CBSQB3 , level of theory, and the lowest energy conformers were used as the final geometries. The electronic energy (EE) was calculated at the CBSQB3 level of theory, which provides accurate results for thermodynamic and kinetic data according to several studies. − All the transition states were verified as the first-order saddle point on the potential energy surface from the presence of a single imaginary frequency. Intrinsic reaction coordinate (IRC) calculations with a step size of 0.1 Bohr were performed to verify the connection of every transition state with the reactant and product.…”

Theoretical and kinetic modeling study of chloromethane (CH3Cl) pyrolysis and oxidation

“…Besides the direct application to CH 3 Cl pyrolysis and oxidation, this model constitutes a solid basis for better assessing the influence of the chlorinated function and for further extension to higher molecular weight molecules 22,23 or to molecules with multiple chlorine substitution. Indeed, the increasing interest in biomass utilization for energy production, the likely perspective of chemical recycling of solid plastic wastes containing polyvinylchloride, 24 as well as the interest in reducing the environmental impact of chlorinated composite solid materials for rocket propulsion, 25 further motivates the present work.…”