Polychlorinated benzene and polychlorinated phenol in heterogeneous combustion reactions of ethylene and ethane

Ethylene and ethane were reacted with HCl/air under heterogeneous combustion conditions between 300 and 600 degrees C. Model catalyst mixtures of SiO2, SiO2/Al2O3, and SiO2/CuO were compared with municipal waste incinerator (MWI) fly ash. Chlorinated benzenes (Cl(x)Bz) and chlorinated phenols (Cl(x)Ph) were detected in both gas-phase products and catalyst-adsorbed products. In C2H4 reactions over fly ash, the amount of Cl(x)Bz produced increased to 600 degrees C (Cl-5-Bz: 1.6 x 10(4) ng/g C2H4; HCB: 6 x 10(3) ng/g C2H4), while Cl(x)Ph (PCP) production remained constant from 400 to 600 degrees C (1.5 x 10(3) ng/g of C2H4). For C2H6 reactions at 600 degrees C, Cl(x)Bz production was very similar to the C2H4 reaction (Cl(5)Bz: 1.6 x 10(4) ng/g C2H6; HCB: 5 x 10(3) ng/g C2H6), whereas total Cl(x)Ph (PCP) production was an order of magnitude greater (1.2 x 10(4) ng/g C2H6). The CuO-catalyzed gas-phase Cl(x)Bz patterns most closely matched those produced in the reactions with MWI fly ash. The Al2O3-catalyzed reactions distinguished themselves from the others in unique Cl(x)Bz and Cl(x)Ph congener patterns that were dominated by the dichloro homologue group and in the observation of non-chorinated aromatic reaction products, in contrast to a predominance of chlorinated aliphatic compounds in the CuO and fly ash-catalyzed reactions.