Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/26736
- Experimental and computational studies on the gas-phase reaction of CBrF₃ with hydrogen
Kennedy, Eric M.;
Dlugogorski, Bogdan Z.
- Gas-phase hydrogen dehalogenation of halon 1301 (bromotrifluoromethane, CBrF₃) has been studied experimentally in a tubular alumina reactor operating at atmospheric pressure. It is found that hydrogen can accelerate the decomposition of halon 1301 and that conversion levels of CBrF₃ and H₂ increase with temperature and residence time. CBrF₃ conversion increases with decreasing input volume ratio of CBrF₃ to H₂. The species produced are a complex mixture of halogenated hydrocarbons including CHF₃, CH₂F₂, C₂HF₃, C₂F₆, C₂H₂F₄, C₂HF₅, CHBrF₂, CH₃Br, CH₂Br₂, CHBr₂F, and CH₂BrF in addition to HBr and HF. The production yield of CHF₃, the major product, increases with temperature to 1023 K, after which CHF₃ levels decrease with increasing temperature. Conversely, CHF₃ selectivity decreases with increasing temperature, residence time, or input ratio of CBrF₃ to H₂. The initiation reaction is believed to be the rupture of the C-Br bond in CBrF₃, and the radical species CF₃ then reacts with H₂ to produce H and CHF₃. The key step in the process is the attack of H radical on CBrF₃ to produce CF₃ and HBr. Experimental data are compared with the model predictions, and good agreement between experimental and modeling prediction is obtained for CHF₃ production. However, the existing mechanism does not predict the formation of CHBrF₂, which is detected during the experimental study, and the concentrations of CH₂F₂ and C₂F₆ measured experimentally are significantly different from those predicted. Modifications to the existing NIST mechanism are suggested to improve the prediction of the quantity of these species produced.
- Environmental Science & Technology Vol. 34 , Issue 4, p. 584-590
- Publisher Link
- American Chemical Society
- Resource Type
- journal article