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-NO x catalysts especially in the case of municipal waste incineration plants. Samples of a commercial selective catalytic reduction catalyst were impregnated with different amounts of Pb(NO 3 ) 2, and their catalytic activities were studied. 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 samples. Pb covers the surface of inactive TiO 2 sites, likewise active V 2 O 5 /WO 3 sites, in a thin, noncrystalline layer. Both activity and NH 3 chemisorbed decreased in the same manner with increasing poison coverage. This suggests that the area available for reaction was the same or at least proportional to that for the adsorption of NH 3 and deactivation of the catalyst may be due to competitive chemisorption of the poison on the acid sites instead of by pore blocking.