Experimental study of SO2 adsorption on barium-based NOx adsorbers

When subjected to SO(2), NOx adsorbers (containing BaO, alumina and ceria) adsorb SO(2) due to the formation of different sulfates such as those of aluminum, cerium and barium. The sulfation process is promoted by the presence of platinum and inhibited by rhodium. Under nitrogen atmosphere, barium sulfate decomposes at a temperature close to 1000 degrees C. Aluminum and cerium sulfates decompose at 500-800 degrees C. NO and SO(2) compete for adsorption when they are simultaneously injected. NO and SO(2) adsorb on accessible BaO sites, whereas SO(2) also adsdrbs on the support, which contains alumina and ceria. The NOx storage capacity of the adsorber decreases when subjected. to successive treatments with SO(2). (C) 2000 Elsevier Science B.V. All rights reserved.