Reductive and oxidative destruction of chlorinated hydrocarbons in gas-phase catalytic reactors: Packed-beds and modified fuel cells

The catalytic destruction of trichloroethylene and perchloroethylene was studied in a packed-bed reactor (Pt/alumina) and a modified fuel cell (Pt/carbon cloth) to treat soil-vapor extraction gases. Mechanisms and conditions for which reductive dehalogenation and oxidation of the targets occur when both hydrogen and oxygen are present in the reactive mixture were established. Low temperatures (< 200°C) favored reductive dehalogenation of the targets and produced ethane, while higher temperatures (between 200° and 400°C) favored oxidative dehalogenation and produced CO ₂. Reductive dehalogenation of the targets was achieved in the cathode of the modified fuel cell using cell potential (0.1-0.4 v cathode relative to anode) to control the supply of hydrogen for the reaction by reformation of hydrogen gas in the cathode from protons produced in the anode. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA 8/22-26/2004).