Pyrolysis and Oxidation of 1,1,1-Trichloroethane in Methane/Oxygen/Argon

Abstract

The thermal decomposition of 1,1,1-trichloroethane in methane/oxygen mixtures and argon bath gas was carried out at 1 atmosphere total pressure in a tubular flow reactor over temperature range 500 to 800°C, with average residence times between 0.05 to 2.5 seconds. Five reactant ratio sets in three different size flow reactors were studied. Complete decay of the 1,1,1-trichloroethane at 1 second residence time occurs at about 600°C for all the reactant sets. The major products for 1,1,1-trichloroethane decomposition are 1,1-dichloroethylene and HCl. Oxygen has almost no effect on the decay of 1,1,1-trichloroethane in our study. Formation of CH2CCl2 as one of major products from CH3CCl3 increases with increasing temperature to a maximum near 600°C at 1.0 sec residence time and is independent of reactant ratio here. It then drops quickly with increasing temperature and increased O2. Higher ratios of O2 to CH4, result in lower temperatures needed to observe formation of CO and CO2. The major products at temperature above 750°C are HCl, HC=CCl and nonchlorinated hydrocarbons: C2H2, C2H4, CO and CO2. A detailed kinetic reaction mechanism based on thermochemical principles was developed and used to model results obtained from the experiments. Sensitivity analysis of the model was done to show the most important reactions in the mechanism.