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 °C. Model catalyst mixtures of SiO 2, SiO 2 /Al 2 O 3, and SiO 2 /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 C 2 H 4 reactions over fly ash, the amount of Cl x Bz produced increased to 600 °C (Cl 5 Bz: 1.6 × 10 4 ng/g C 2 H 4; HCB: 6 × 10 3 ng/g C 2 H 4 ), while Cl x Ph (PCP) production remained constant from 400 to 600 °C (1.5 × 10 3 ng/g of C 2 H 4 ). For C 2 H 6 reactions at 600 °C, Cl x Bz production was very similar to the C 2 H 4 reaction (Cl 5 Bz: 1.6 × 10 4 ng/g C 2 H 6; HCB: 5 × 10 3 ng/g C 2 H 6 ), whereas total Cl x Ph (PCP) production was an order of magnitude greater (1.2 × 10 4 ng/g C 2 H 6 ). The CuO-catalyzed gas-phase Cl x Bz patterns most closely matched those produced in the reactions with MWI fly ash. The Al 2 O 3 -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.