Formation of Chlorinated Organics During Solid Waste Combustion

Abstract

The formation mechanisms of the precursors of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) were examined in a laboratory reactor. Both homogeneous and heterogeneous reactions were studied between 200 and 800°C with HCl, Cl₂, and phenol as reactants in a simulated flue gas containing oxygen. Analysis of the reactor effluent showed that homogeneous phase production of chlorophenols and non-chlorinated dioxin and dibenzopdioxin and dibenzofuran, benzofuran potential precursors to PCDD and PCDF, was related to HCl concentration, reaching a maximum formation level around 650°C. However, Cl₂ produced a greater variety of chlorinated aromatics at levels over three orders of magnitude greater than with HCl, with product concentrations reaching maximum formation levels around 350°C. Heterogeneous tests at 450°C using a CuCl catalyst increased formation of chlorinated organics and PCDDs and identified the major chlorinating reactant to be Cl₂.