DEACTIVATING EFFECTS OF LEAD ON THE SELECTIVE CATALYTIC REDUCTION OF NITRIC-OXIDE WITH AMMONIA OVER A V2O5 WO3/TIO2 CATALYST FOR WASTE INCINERATION APPLICATIONS/

Lead is one of the poisonous elements for de-NOx catalysts especially in the case of municipal waste incineration plants. Samples of a comme rcial selective catalytic reduction catalyst were impregnated with dif ferent amounts of Pb(NO3)(2), and their catalytic activities were stud ied. The XPS and SEM analysis showed higher lead concentration on the outer surface of the monolith than on the inside of the wall for all s amples. Pb covers the surface of inactive TiO2 sites, likewise active V2O5/WO3 sites, in a thin, noncrystalline layer. Both activity and NH3 chemisorbed decreased in the same manner with increasing poison cover age. This suggests that the area available for reaction was the same o r at least proportional to that for the adsorption of NH3 and deactiva tion of the catalyst may be due to competitive chemisorption of the po ison on the acid sites instead of by pore blocking.