Development of expanded and core kinetic models for the gas phase formation of dioxins from chlorinated phenols.

Expanded, 45 reaction, and core, 12 reaction, kinetic models have been developed that account for the major features in the homogeneous formation of polychlorinated dibenzo-p-dioxins (PCDD) from the oxidation of 2,4,6-trichlorophenol (P). The expanded and core schemes provide good agreement between experimental and calculated yields of PCDDs using the CHEMKIN combustion package or the React kinetic program, respectively. Steady-state approximations of the reaction kinetic models including radical-molecule and radical-radical formation pathways of PCDD, as well as oxidative destruction pathways of chlorinated phenoxyl radicals, reveal a competition between reactions of chlorinated phenoxyl radicals with chlorinated phenols, recombination reactions of chlorinated phenoxyl mesomers, and destruction/decomposition of phenoxyl radicals.