Combustion of aliphatic C2 chlorohydrocarbons over ceria-zirconia mixed oxides catalysts

The complete oxidation of chlorinated aliphatic hydrocarbons, such as 1,2-dichloroethane, and trichloroethylene, over CexZr1-xO2-based catalysts has been studied using a conventional fixed bed flow reactor. The mixed oxide catalysts exhibited a higher activity with respect to the pure oxides, and catalytic conversion was found to depend on Ce/Zr molar content. Thus, Ce0.5Zr0.5O2 showed the highest combustion activity for the abatement of both chlorohydrocarbons. The combination of surface acidity and accessible lattice oxygen appeared to control the catalytic performance of the mixed oxides. The major oxidation products were CO2, HCl and Cl-2 along with trace amounts of other chlorinated by-products, namely vinyl chloride and tetrachloroethylene, and carbon monoxide. The selectivity toward CO2 and Cl-2 was found to be noticeably promoted with increasing cerium content. Thus behaviour was related to the high activity of ceria in CO and HCl oxidation to give Cl-2 by the Deacon reaction. (C) 2004 Elsevier B.V. All rights reserved.