EXHAUST GAS PURIFYING CATALYST

• Main Authors: YAMASHITA YOSHINORI, AONO NORIHIKO
• Format: Patent
• Language: English; Japanese
• Published: 13.04.2017
• 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

PROBLEM TO BE SOLVED: To provide an exhaust gas purifying catalyst having excellent purification performance in a low temperature range.SOLUTION: In an exhaust gas purifying catalyst of the present invention, a catalyst layer 3 includes a mixture of: a first supported catalyst 31 comprising a first carrier 311 made of alumina and platinum and palladium 312 carried by the first carrier 311, wherein the mass ratio of the platinum to the palladium is 2-7, the alloying ratio of the platinum and the palladium is 40% or more, and the average particle diameter of the platinum is 13 nm or less; a second supported catalyst 32 comprising a second carrier 321 consisting of a cerium-containing oxide in which the proportion of cerium in all elements other than oxygen is 15 mass% or more, and palladium 322 carried by the second carrier 321; and zeolite 33. The proportion of the palladium contained in the second supported catalyst 32 in the total amount of the platinum contained in the first supported catalyst 31 and the palladium contained in the second supported catalyst 32 is in the range of 20-50 mass%.SELECTED DRAWING: Figure 3 【課題】低温域において、優れた浄化性能を有する排ガス浄化用触媒を提供する。【解決手段】本発明の排ガス浄化用触媒は、触媒層３が、アルミナからなる第１担体３１１と、前記第１担体３１１に担持された、白金及びパラジウム３１２とを含み、白金とパラジウムとの質量比は２乃至７の範囲内にあり、白金及びパラジウムの合金化率は４０％以上であり、白金の平均粒径は１３ｎｍ以下である第１担持触媒３１と、酸素以外の全元素に占めるセリウムの割合は１５質量％以上であるセリウム含有酸化物からなる第２担体３２１と、前記第２担体３２１に担持されたパラジウム３２２とを含んだ第２担持触媒３２と、ゼオライト３３との混合物を含み、前記第１担持触媒３１が含む白金と前記第２担持触媒３２が含むパラジウムとの合計量に占める前記第２担持触媒３２が含むパラジウムの割合は２０乃至５０質量％の範囲内にある。【選択図】図３