THE DEVELOPMENT OF SUPPORTED VANADIA CATALYSTS FOR THE COMBINED CATALYTIC REMOVAL OF THE OXIDES OF NITROGEN AND OF CHLORINATED HYDROCARBONSFROM FLUE-GASES

Supported vanadia catalysts are commercially used to remove the oxides of nitrogen contained in oxygen-containing flue gases by selective ca talytic reduction (SCR) using ammonia as reductant. This paper examine s the possibility of using the same catalysts for the complete oxidati on of chlorinated hydrocarbons (ethyl chloride or chlorobenzene) in th e presence of NO and ammonia. It is shown that vanadia supported on an alumina-modified zirconia is capable of giving 100% conversion of the chlorinated molecules while giving also 100% conversion of the NO ove r a relatively wide range of temperature (593-683 K). This material al so shows a resistance to poisoning by HCl but it is slowly poisoned by SO2 if present. The addition of tungsten oxide to the formulation has no significant effect on the catalytic behaviour towards NO and ethyl chloride but it improves the resistance to SO2.