Activity and product distribution of alumina supported platinum and palladium catalysts in the gas-phase oxidative decomposition of chlorinated hydrocarbons

The complete catalytic oxidation of 1,2-dichloroethane (DCE) and trichloroethylene (TCE) over alumina supported noble metal catalysts (Pt and Pd) was evaluated. Experiments were performed at conditions of lean hydrocarbon concentration (around 1000 ppm) in air, between 250 degrees C and 550 degrees C in a conventional fixed bed reactor. The catalysts were prepared in a range of metal contents from 0.1 to 1 wt%. Palladium catalysts resulted to be more active than platinum catalysts in the oxidation of both chlorinated volatile organic compounds. DCE was completely destructed at 375 degrees C, whereas TCE required 550 degrees C. HC1 was the only chlorine-containing product in the oxidation of DCE in the range of 250-400 degrees C. Tetrachloroethylene was observed as an intermediate in the oxidation of TCE, being; formed to a significant extent between 400 degrees C and 525 degrees C. CO was also detected in the oxidation of both DCE and TCE over Pd catalysts, though at temperatures of complete destruction, CO2 was the only carbon-containing product. The Pt catalysts were selective to CO2 at the studied contionons. (C) 1998 Elsevier Science B.V. All rights reserved.