Catalytic combustion of chlorinated ethylenes over H-zeolites

Several H-zeolites (H-Y, H-ZSM-5 and H-MOR) were investigated for the catalytic combustion of chlorinated ethylenes, namely 1,1-dichloroethylene and trichloroethylene. Conversion was inversely related to the chlorine content of the feed molecule. H-ZSM-5 zeolite was the most active catalyst in 1,1-dichloroethylene combustion whereas H-MOR was the most effective zeolite for trichloroethylene destruction. Temperature-programmed desorption of ammonia and diffuse reflectance FT-IR measurements of adsorbed pyridine revealed that strong Bronsted acidity plays an important role in controlling the activity of H-zeolites. The main combustion products were CO, CO2, HCl, and Cl-2. Additionally, small amounts of highly chlorinated by-products were also detected, namely trichloroethylene and tetrachloroethylene. H-zeolites showed a great selectivity to HCl formation. (C) 2002 Society of Chemical Industry.