Effect of Sulfur Dioxide on the Formation Mechanism of PolychlorinatedDibenzodioxin and Dibenzofuran in Municipal Waste Combustors

摘要

The paper gives results of an investigation of the effect of SO2 on the formationmechanism of polychlorinated dibenzodioxin (PCDD) and polychlorinated dibenzofuran (PCDF) in the post-combustion, downstream region (500 to 300 C) of a municipal waste combustor (MWC). Laboratory experiments simulating the flue gases and particle environment of an MWC examined PCDD production under varying conditions. Effects on the concentration of the organic-chlorinating constituent, Cl2, through both homogeneous reaction with SO2 and deactivation of a Cl2-forming catalyst, Cu(II), were examined. Experimental results suggest that the reaction of Cu(II) with SO2 to form CuSO4 renders the catalyst less active, decreasing PCDD formation by minor amounts. However, this inactivity is not the result of decreased Cl2 formation, but rather of reduced ability of Cu(II) to promote a second catalytic step of biaryl synthesis. These findings suggest that the apparent lack of PCDD and PCDF in the emissions from coal-fired combustors may be due to the relatively high concentrations of SO2. (Copyright (c) 1992 American Chemical Society.)