Chemical Considerations in the Incineration of Chlorinated Methanes I-Methyl Chloride

Abstract

The high temperature product distributions from reactions of methane and methyl chloride have been measured under pyrolysis, preignition oxidation and flame conditions. For pyrolysis and preignition data, 3% fuel/zero oxygen or stoichiometric oxygen/10% N₂/Ar were heated behind reflected shocks to temperatures between 1200-2600 K at a density of approximately 2.5 ± 0.25 × 10⁻⁵ mol/cm³. Flame studies were conducted at atmospheric pressure for methane/air and methyl chloride/methane/air mixtures with equivalence ratios of 1.15 and 1.35 and for four methyl chloride/methane ratios ranging from pure methane to pure methyl chloride. Methyl chloride is more easily decomposed than methane in either pyrolysis or preignition oxidation. This is because of the lower bond dissociation energy of methyl chloride (D_o (CH₃-Cl) = 334 kJ/mol) as compared to methane (D_o(CH₃-H) = 435 kJ/mol). In the flame environment, the methane and methyl chloride disappear at approximately the same rate. The presence of chlorine decreases the measured ethane concentration and promotes the formation of acetylene which may explain the propensity of soot formation from chlorinated hydrocarbons.