CATALYTIC DECOMPOSITION OF METHYLENE-CHLORIDE BY SULFATED OXIDE CATALYSTS

Catalytic decomposition of methylene chloride in air with a concentrat ion of 959 ppm and temperature ranges from 160 to 275 degrees C were s tudied. Three different sulfated oxide catalysts, TiO2-(SO4), ZrO2-(SO 4), CeO2-(SO4) were prepared and their activities and selectivities we re measured. The catalytic activity decreased in the order: TiO2-(SO4) > ZrO2-(SO4) > CeO2-(SO4). Complete catalytic decomposition of methyl ene chloride was achieved at low temperature (275 degrees C) over a su lfated titanium dioxide catalyst. The oxygen adsorption (pick-up) and the acidity values of three catalysts showed the same trend as their a ctivities. The presence of water (2% in volume) in the feed stream red uced the activities remarkably and raised the activation energies for the decomposition reaction. The selectivities among all three catalyst s were similar, with HCl, CO and CO2 being the products. A bifunctiona l catalyst comprising sulfated titanium dioxide with copper oxide was developed to improve the selectivity of catalytic oxidation of methyle ne chloride towards carbon dioxide.