An experimental and numerical study of the thermal oxidation of chlorobenzene.

A combustion-driven flow reactor was used to examine the formation of chlorinated and non-chlorinated species from the thermal oxidation of chlorobenzene under post-flame conditions. Temperature varied from 725 to 1000 K, while the equivalence ratio was held constant at 0.5. Significant quantities of chlorinated intermediates, vinyl chloride and chlorophenol, were measured. A dominant C-Cl scission destruction pathway seen in pyrolytic studies was not observed. Instead, hydrogen-abstraction reactions prevailed, leading to high concentrations of chlorinated byproducts. The thermal oxidation of benzene was also investigated for comparison. Chemical kinetic modeling of benzene and chlorobenzene was used to explore reaction pathways. Two chlorobenzene models were developed to test the hypothesis that chlorobenzene oxidation follows a CO-expulsion breakdown pathway similar to that of benzene. For the temperatures and equivalence ratio studied, hydrogen abstraction by hydroxyl radicals dominates the initial destruction of both benzene and chlorobenzene. Chlorinated byproducts (i.e., chlorophenol and vinyl chloride) were formed from chlorobenzene oxidation in similar quantities and at similar temperatures to their respective analogue formed during benzene oxidation (i.e., phenol and ethylene).