| 摘要 |
PROBLEM TO BE SOLVED: To keep the dispersibility of alkali metal and to suppress diffusion, transpiration and sulfur poisoning in an occluding reduction type exhaust gas purifying catalyst using at least alkali metal to enhance the durability of the catalyst. SOLUTION: In an exhaust gas purifying catalyst occluding NOx in a lean atmosphere and discharging the same in a stoichiometric-rich atmosphere to reduce NOx, an NOx occluding material is constituted of a composite compd. containing a first element selected from alkali metals and a second element selected from one of alkaline earth metals, rare earth elements and transition metals. Since the diffusion or transpiration of the first element is suppressed by the second element by using the composite compd., even if high temp. heat acts, the first element is kept carried in a highly dispersed state. |
