The nonoxidative gas-phase reaction of halon 1211 (CBrClF₂) with methane was studied using a tubular plug-flow alumina reactor at atmospheric pressure, over the temperature range of 673-1073 K, and at residence times between 0.1 and 1.3 s. With an equimolar feed of CBrClF₂ and CH₄, complete halon conversion was achieved at 1073 K for all residence times considered. The initial products of the reaction are CHClF₂ and CH₃Br, which are replaced by C₂H₂F₂ at elevated temperatures. We suggest C₂H₂F₂ is produced from the direct coupling of CH₃ and CF₂Cl radicals, which rapidly decompose to C₂H₂F₂ and HCl. Minor products formed during reaction include C₂H₃F, CHF₃, C₂F₄, CHBrF₂, and C₂HBrF₂. The formation of CHClF₂, C₂F₄, CHBrF₂, and C₂HClF₂ was observed to reach a maximium at specific residence times, and formation of soot was detected above 943 K. Possible mechanistic pathways for major and some minor species are discussed.
Industrial & Engineering Chemistry Research Vol. 40, Issue 14, p. 3139-3143