Experimental and Computational Studies of the Gas-Phase Reaction of Halon 1211 with Hydrogen

Abstract

The gas-phase reaction of halon 1211 (CBrClF2) with hydrogen has been studied experimentally at atmospheric pressure in a plug flow, isothermal reactor over the temperature range of 673 to 973 K, at residence times ranging from 0.5 to 2.5 s with an input ratio of N2:H2:halon 1211 of 19:10:1. The major carbon containing products include CHClF2, CHBrF2, CH2F2, and CH4. Gas-phase reactions of CHClF2, CCl2F2, and CH2F2 with hydrogen are also investigated under the conditions similar to those for halon 1211 hydrodehalogenation, and the results are used to assist in understanding the mechanism of the reaction of halon 1211 with hydrogen. A kinetic reaction scheme involving 90 species and 430 reaction steps is developed and used to model the halon 1211 hydrodehalogenation reaction. Generally, satisfactory agreement between experimental and computational results is obtained for the production of major species. Using the software package AURORA, the reaction pathways leading to the formation of major products are elucidated. It has been found that the reaction steps involving CF2 are responsible for the formation of CH4.

High-Temperature Fluorocarbon Chemistry Revisited

“…Information on high-temperature reactions of fluorocarbons is of interest for not only fundamental but also practical reasons. Fluorocarbons find industrial applications, for example, as etching and cleaning agents in microelectronic manufacturing or in fire retardation. , A quantitative understanding of the abatement of fluorocarbon emissions from such activities, or of emissions arising from the incineration of perfluoropolymer wastes, is only at its beginning. , The following study provides more data for the modeling of such processes.…”

Experimental and Chemical Kinetics Study of the Effects of Halon 1211 (CF2BrCl) on the Laminar Flame Speed and Ignition of Light Hydrocarbons

“…The Halon 1211 model uses various submodels from the literature as a foundation. These models are the recent C 3 H 2 F 3 Br model of Babushok et al 12 (which also includes the CF 3 Br chemistry), while reactions involving chlorine have been taken from the HCFC-123 (C 2 HCl 2 F 3 ) model of Babushok et al 35 As mentioned earlier, the pyrolysis of Halon 1211 with 21 and without 22 H 2 was detailed by Yu et al, and these submechanisms have been used as a starting point to develop the oxidation chemistry of CF 2 BrCl. In cases of duplicate reactions, the rates adopted by Babushok and coworkers were kept.…”

“…The effects of CF 3 Br and CF 2 BrCl were also studied with nbutane combustion, but only at low temperatures (573−673 K). 20 Finally, it is worth mentioning that except for the studies by Yu et al on the high-temperature pyrolysis of CF 2 BrCl with 21 and without 23 hydrogen, no studies are available describing the detailed chemistry of Halon 1211 under practical combustion conditions.…”

Theoretical study of the kinetics of reactions of the monohalogenated methanes with atomic chlorine

“…Therefore, the equations (10–12) should reliably describe the values and temperature dependence of k(CH 2 X+HCl) in the temperature ranges given above. The kinetics of the hydrodehalogenation of CF 2 ClBr with hydrogen has been experimentally studied by Yu et al [66] at the high temperatures of 673 – 973 K. In their kinetic computational model, the temperature dependence of the rate constant for reaction CH 2 F + HCl was described by the Arrhenius equation of 9.56×10 −13 ×exp(−1225/T) cm 3 molecule −1 s −1 estimated by referring to the analogous reactions of the halogenated methyl radicals with hydrogen bromide [66]. This leads to values of the rate constant k (CH 2 F+HCl) of 1.66×10 −13 , 2.06×10 −13 and 2.45×10 −13 cm 3 molecule −1 s −1 at 700, 800 and 900 K, respectively.…”