Gas-phase mechanism for dioxin formation.
We consider the formation of dioxin in the gas phase through the combination of phenoxy radicals in the context of a recently published scenario regarding the possibility of forming highly chlorinated benzenes in poorly mixed systems. It is demonstrated that the production of free chlorine in fuel lean combustion systems and subsequent mixing and quenching with fuel rich mixtures leads to chlorine atoms as the main reactive radicals. Under such conditions high concentrations of chlorinated phenoxy radicals can be formed. This leads to the formation of concentrations of dioxins that are consistent with recent measurements of Sidhu et al. [Combust. Flame 100 (1995) 11]. It suggests that there may be a gas-phase channel for the dioxin formation in addition to the usually assumed surface catalyzed process.
Babushok
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National Institute of Standards and Technology, 100 Bureau Drive, Stop 8380, Gaithersburg, MD 20899-8380, USA. vbabushok@nist.gov
Tsang
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D004147:Dioxins / Q000737:chemistry*; D004785:Environmental Pollutants / Q000032:analysis*; D005609:Free Radicals / Q000737:chemistry; D005740:Gases; D017745:Incineration; D007700:Kinetics; D008956:Models, Chemical; D010636:Phenols / Q000737:chemistry; D012037:Refuse Disposal
D004147:Dioxins; D004785:Environmental Pollutants; D005609:Free Radicals; D005740:Gases; D010636:Phenols; C042329:phenoxy radical