Exhaust gas purifying catalyst and exhaust gas purifying system
AssigneeMazda Motor Corporation
InventorsSeiji Miyoshi, Akihide Takami, Hiroshi Yamada, Kenji Okamoto
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Abstract
An exhaust gas purifying catalyst comprises a substrate, an inner catalytic layer coated on the substrate, an intermediate catalytic layer containing Pd laid over said inner catalytic layer, and an outer catalytic layer containing a NOx adsorption material laid over said intermediate catalytic layer. The Pd isolated from the NOx adsorption material is prevented from lowering its low temperature activity.
Claims6
An exhaust gas purifying catalyst comprising at least a metal selected from a group of alkaline metals and alkaline earth metals;
- and Pd, wherein said Pd is partly isolated from said metal so as to be neither electrically nor chemically affected by said metal.
An exhaust gas purifying system for purifying exhaust gases discharged into an exhaust line from an engine, said exhaust gas purifying system comprising:
- a catalyst disposed in said exhaust line, said catalyst comprising at least a metal selected from a group of alkaline metals and alkaline earth metals, a NOx adsorption material operative to adsorb NOx in said exhaust gas while said exhaust gas has a comparatively high oxygen concentration and release said NOx adsorbed therein and adsorbs SOx as said exhaust gas lowers its oxygen concentration, and Pd;
- and
- temperature control means for raising a temperature of said catalyst so as thereby to cause said NOx adsorption material to release said SOx adsorbed therein;
- wherein said Pd is partly isolated from said NOx adsorption material so as to be neither electrically nor chemically affected by said NOx adsorption material.
Dependencies are inferred from the claim text.