EXHAUST GAS PURIFYING CATALYST

摘要

PURPOSE:To accelerate NOx reducing reaction by further supporting ceria on an exhaust gas purifying catalyst having an NOx absorbing material and a noble metal catalyst not only to absorb the fluctuations of A/F at the time of a stoichiometric state but also to prevent the oxidation reaction of HC and CO due to a large amt. of high speed oxygen discharged from ceria. CONSTITUTION:In this exhaust gas purifying catalyst constituted by supporting an NOx absorbing material 4 and a noble metal catalyst 3 on a porous carrier, ceria 21 is further supported on the porous carrier and the noble metal catalyst 3 is prevented from being obstructed by the oxygen discharge action of ceria 21 supported in the vicinity of the NOx absorbing material 4 and the reduction reaction of NOx absorbed into the NOx absorbing material 4 is generated at first by the noble metal catalyst 3. Since ceria 21 is not present in the vicinity of the noble metal catalyst 3, the oxygen discharge speed and amt. of ceria 21 are lowered and it is prevented that the noble metal catalyst is oxidized before HC and CO are reacted with NOx.