Role of water and other H-rich additives in the catalytic combustion of 1,2-dichloroethane and trichloroethylene

In several practical applications gas streams containing chlorinated volatile organic compounds with variable chemical nature (namely, 1,2-dichloroethane and trichloroethylene) and a significant moisture content (15 000 ppm) must be addressed. In this paper the control of such emissions by catalytic oxidation over Ce/Zr mixed oxides was analysed. Results in terms of activity and selectivity were compared with those obtained when other H-rich additives (1000 ppm), such as hexane or toluene, were fed. High activity was found from mixed oxides featuring a suitable combination of a large population of acid sites, easily accessible oxygen species, and hydrophobic nature attributable to cerium content. The presence of additional H-rich compounds in the feed stream (water, toluene or hexane) tended to decrease the catalytic activity due to the blockage and/or competition for actives sites. However, the increased presence of hydrogen atoms in the stream notably promoted the selectivity to hydrogen chloride instead of molecular chlorine. (C) 2009 Elsevier Ltd. All rights reserved.