Experimental study of SO2 adsorption on barium-based NOx adsorbers

When subjected to SO2, NOx adsorbers (containing BaO, alumina and ceria) ad sorb SO2 due to the formation of different sulfates such as those of alumin um, cerium and barium. The sulfation process is promoted by the presence of platinum and inhibited by rhodium. Under nitrogen atmosphere, barium sulfa te decomposes at a temperature close to 1000 degrees C. Aluminum and cerium sulfates decompose at 500-800 degrees C. NO and SO2 compete for adsorption when they are simultaneously injected. NO and SO2 adsorb on accessible BaO sites, whereas SO2 also adsdrbs on the support, which contains alumina and ceria. The NOx storage capacity of the adsorber decreases when subjected. to successive treatments with SO2. (C) 2000 Elsevier Science B.V. All right s reserved.