EXHAUST GAS PURIFYING CATALYST

• Main Authors: YAZAWA YOSHITERU, NISHIO TAKAHIRO, TOJO TAKUMI, CHINZEI ISAO
• Format: Patent
• Language: English; Japanese
• Published: 19.01.2023
• Subjects: BLASTING; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; ENGINE PLANTS IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL; HEATING; LIGHTING; MACHINES OR ENGINES IN GENERAL; MECHANICAL ENGINEERING; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; STEAM ENGINES; THEIR RELEVANT APPARATUS; TRANSPORTING; WEAPONS

To provide an exhaust gas purifying catalyst having improved OSC performance while maintaining exhaust gas cleaning performance.SOLUTION: A exhaust gas purifying catalyst having a substrate 11 and at least one catalyst layer 12 formed on the substrate, in which an uppermost catalyst layer 14 comprises: a catalyst metal; a first OSC material having a pyrochlore structure; a second SOC material higher in oxygen absorption and release speed than the first SOC material; an upstream catalyst layer 15 formed on an upstream side of a flow direction of an exhaust gas; and an a downstream side catalyst layer 16 formed on a downstream side in a flow direction of the exhaust gas. In the upstream side catalyst layer 15, a mass ratio of the second OSC material to a total mass of the first OSC material and the second OSC material is 0.55 to 0.73. In the downstream side catalyst layer 16, the mass ratio of the second OSC material to the total mass of the first OSC material and the second OSC material is 0.27 to 0.55.SELECTED DRAWING: Figure 1 【課題】排ガス浄化性能を維持しつつＯＳＣ性能が向上した排ガス浄化用触媒を提供する。【解決手段】基材１１と、基材上に形成された少なくとも１層の触媒層１２を有する排ガス浄化用触媒であって、最上層の触媒層１４が、触媒金属と、パイロクロア構造を有する第１のＯＳＣ材と、第１のＯＳＣ材よりも酸素吸放出速度が速い第２のＯＳＣ材を含み、且つ、排ガスの流れ方向の上流側に形成された上流側触媒層１５と、排ガスの流れ方向の下流側に形成された下流側触媒層１６からなり、上流側触媒層１５において、第１のＯＳＣ材及び第２のＯＳＣ材の合計質量に対する第２のＯＳＣ材の質量割合が０．５５～０．７３であり、下流側触媒層１６において、第１のＯＳＣ材及び第２のＯＳＣ材の合計質量に対する第２のＯＳＣ材の質量割合が０．２７～０．５５である、排ガス浄化用触媒とする。【選択図】図１