CN-121988320-A - Ternary catalyst and method for producing same

Abstract

The invention relates to a three-way catalyst and a manufacturing method thereof. Provided is a three-way catalyst having high heat resistance and both catalytic performance and OSC performance, and a method for producing the same. Several embodiments of the present invention relate to a three-way catalyst and a method of manufacturing the same. The three-way catalyst comprises a noble metal, an OSC material and an oxide solid solution containing barium and zirconium, wherein the noble metal is supported on the OSC material, the molar ratio (Ba: zr) of barium to zirconium in the oxide solid solution is in the range of 20:80-49:51, and the content of barium carbonate and barium oxide in the oxide solid solution is below 2 wt%.

Inventors

• MIURA MASAHIDE
• YAMAMOTO Tomoka
• Nitta Masaya
• HIRABAYASHI TAKESHI
• SHIRAKAWA SHOGO
• KUMATANI NAOKI
• MORIKAWA AKIRA
• HATANAKA MIHO
• ODA TAKASHI
• NANJO TSUBASA

Assignees

• 丰田自动车株式会社
• 株式会社丰田中央研究所
• 株式会社科特拉

Dates

Publication Date

20260508

Application Date

20251107

Priority Date

20241108

Claims (5)

1. 1. A three-way catalyst comprising a noble metal, an OSC material and an oxide solid solution containing barium and zirconium, The noble metal is supported on the OSC material, The molar ratio of barium to zirconium in the oxide solid solution, namely Ba to Zr is in the range of 20:80-49:51, The content of barium carbonate and barium oxide in the oxide solid solution is 2 wt% or less relative to the total weight of the oxide solid solution.
2. 2. The three-way catalyst according to claim 1, The oxide solid solution is a perovskite type oxide.
3. 3. The three-way catalyst according to claim 2, The molar ratio of barium to zirconium in the oxide solid solution, namely Ba to Zr, is in the range of 30:70-49:51.
4. 4. The three-way catalyst according to any one of claim 1 to 3, The content of barium carbonate and barium oxide in the oxide solid solution is 1 wt% or less.
5. 5. A method of manufacturing a three-way catalyst comprising: (i) A step of preparing an oxide solid solution containing barium and zirconium by coprecipitating barium and zirconium from an aqueous solution containing a barium compound and a zirconium compound, and firing the precipitate at 1000 ℃ to 1400 ℃, wherein the molar ratio of barium to zirconium in the oxide solid solution, namely, ba: zr, is adjusted to be in the range of 20:80 to 49:51; (ii) A step of mixing and drying an OSC material with an aqueous solution containing a noble metal to prepare an OSC material carrying a noble metal, and (Iii) And a step of producing a three-way catalyst by mixing the oxide solid solution produced in the step (i) with the OSC material carrying the noble metal produced in the step (ii).

Description

Ternary catalyst and method for producing same Technical Field Several embodiments of the present invention relate to a three-way catalyst and a method of manufacturing the same. Background Exhaust gas (exhaust gas) discharged from an internal combustion engine used for automobiles and the like, for example, a gasoline engine or a diesel engine contains harmful components such as carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and the like. Therefore, in general, an exhaust gas purifying apparatus for decomposing and removing these harmful components is provided in an internal combustion engine, and these harmful components are almost harmless by an exhaust gas purifying catalyst, for example, a three-way catalyst, which is installed in the exhaust gas purifying apparatus. The three-way catalyst contains a noble metal that functions to promote both the oxidation reaction of CO and HC and the reduction reaction of NOx. Noble metals are expensive and are also required to be reduced from a resource risk standpoint. In order to reduce the amount of the noble metal, it is sufficient to prevent the catalytic activity of the noble metal from decreasing due to the use of the exhaust gas purifying catalyst, and in order to prevent the catalytic activity of the noble metal from decreasing, for example, poisoning (HC poisoning) of the noble metal caused by HC in the exhaust gas, which is one of the main causes of the decrease in the catalytic activity of the noble metal, is suppressed. For example, patent document 1 discloses an exhaust gas purifying catalyst characterized in that an active metal is supported on a carrier containing BaAl 2O4 and BaZrO 3. Patent document 2 discloses a mixed catalyst comprising, as main components, a catalyst a having an active metal α on the surface of a support a mainly composed of Ba, al, zr, and oxides thereof, and a catalyst B having an active metal β on the surface of a support B mainly composed of ceria, wherein the ratio (a/(a+b) ×100) of the mass of the catalyst a to the total mass of the catalyst a and the catalyst B exceeds 10 mass% and is smaller than 80 mass%. Patent document 3 discloses an exhaust gas purifying catalyst which is disposed in an exhaust pipe of an internal combustion engine and which is configured to purify exhaust gas discharged from the internal combustion engine, and which is characterized by comprising a substrate and a catalyst layer formed on the substrate, wherein the catalyst layer has an alkaline earth metal supporting region, the alkaline earth metal supporting region comprises a porous support made of an inorganic compound, pt supported on the porous support, and at least one sulfate of alkaline earth metals supported on the porous support, and wherein when a cross section of the alkaline earth metal supporting region of the catalyst layer is subjected to surface analysis by FE-EPMA under conditions of a pixel size of 0.34 μm×0.34 μm and a measured pixel number of 256×256, an intensity (α: cps) of characteristic X-rays of an element (Ae) of the alkaline earth metal and an intensity (β: cps) of characteristic X-rays of Pt are measured for each pixel, and when a and β calculated at each pixel obtained by using the porous support are correlated with each other, a value of R Ae/Pt is equal to or more than 0. Ae/Pt. Patent document 4 discloses an exhaust gas purifying catalyst comprising a perovskite type composite oxide composed of at least Ba, zr, Y and Pd. Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication No. 2010-12459 Patent document 2 Japanese patent application laid-open No. 2013-39520 Patent document 3 Japanese patent laid-open No. 2020-54982 Patent document 4 International publication No. 2020/195600 Disclosure of Invention On the other hand, the three-way catalyst is required to have an oxygen storage capacity (OSC: oxygen Storage Capacity), and the three-way catalyst may contain a material having an OSC (OSC material) in addition to the catalyst metal. "OSC material" refers to a material capable of absorbing and desorbing oxygen. The OSC material can maintain the oxygen concentration constant even when the air-fuel ratio varies, and maintain the purification performance (catalytic performance) of the three-way catalyst. That is, as the three-way catalyst, a three-way catalyst having both of the catalytic performance, i.e., the suppression of HC poisoning by noble metals and OSC performance is desirable. However, in the palladium (Pd) based three-way catalyst, barium (Ba) in alkaline earth metals, such as barium sulfate and barium carbonate, which can be introduced to suppress HC poisoning of noble metals and improve low-temperature activity, moves in the catalyst coating layer under specific high-temperature conditions, and sometimes undergoes solid-phase reaction with OSC materials, such as CeO 2-ZrO2 solid solution (CZ), to lower OSC performance. This is considered because the Ba