NITROGEN OXIDE STORAGE CATALYST, AND MANUFACTURE THEREOF AND ITS USE

PROBLEM TO BE SOLVED: To increase a load of a stored compound by a method wherein in a nitrogen oxide storage catalyst containing a fine catalytic material and a nitrogen oxide storage constituent, the nitrogen oxide storage constituent is so provided as to exist as fine barium sulfate and strontium sulfate after end of manufacturing the catalyst. SOLUTION: In a nitrogen oxide storage catalyst wherein a catalyst so structured as to provide a cover 2 on an inactive support 1 to be used for purifying an exhaust gas of a lean engine or the like, contains fine catalytic materials 3, 4 and a nitrogen oxide storing constituent 5, the nitrogen oxide storing constituent 5 is so formed as to exist as fine barium sulfate, and strontium sulfate, after end of manufacturing the catalyst, further a mixture or a mixed crystal of both sulfates, or as a decomposition product having at most 1 μm in average particle size. As the material 3, an activated aluminum oxide activated by use of platinum is used, and as the material 4, a constituent for storing oxygen or cerium/zirconium mixed oxide activated by use of rhodium is used.