Experimental and computational studies of the thermal decomposition of halon 1211

Thermal pyrolysis of halon 1211 (CBrClF₂). diluted in nitrogen, in a tubular alumina reactor, has been studied over the temperature range of 773-1073 K at residence times from 0.3 to 2 s. At temperatures below 973 K, the major products were CCl₂F₂, CBr₂F₂, C₂Cl₂F₄, C₂BrClF₄, C ₂F₄, and C₂Br₂F₄. Further increasing temperature resulted in the formation of CBrF₃, CCLF ₃, and many other species whose formation necessitated the rupture of C - F bonds. Coke formation was also observed on the surface of the reactor at high temperatures. A kinetic reaction scheme involving 16 species and 25 reaction steps was developed and applied to model the thermal pyrolysis of halon 1211 over the temperature range of 773 - 973 K. Sensitivity analysis suggests that the reaction CBrClF₂ + CClF₂ → CCl ₂F₂ +CBrF₂ constitutes the major pathway for the decomposition of halon 1211 under the conditions investigated.