| 简介 |
PROBLEM TO BE SOLVED : To provide a good NOx occlusion catalyst.SOLUTION : There is provided an NOx occlusion reduction-type catalyst for purifying exhaust gas which comprises a substrate 3, a catalyst lower layer 2 on the substrate 3 and a catalyst upper layer 1, where each of the catalyst lower layer 2 and the catalyst upper layer 1 contains an oxide carrier and a carried metal, the carried metal includes at least one of an alkali metal, an alkaline earth metal and a rare earth element, occludes NOx under a lean atmosphere and discharges NOx in a stoichiometric to rich atmosphere. Further, rhodium is carried on the catalyst lower layer 2, platinum is carried on the catalyst upper layer 1, the catalyst lower layer 2 covers the entire length of an exhaust gas flow passage of the substrate and the catalyst upper layer 1 covers 90% or more and less than 100% of the length to the downstream end with the downstream end of the exhaust gas flow passage as a starting point.SELECTED DRAWING : Figure 1 |
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