JP2019122882A - Core-shell type oxide material, method for producing the same, and exhaust purification catalyst and exhaust purification method using the same - Google Patents
Core-shell type oxide material, method for producing the same, and exhaust purification catalyst and exhaust purification method using the same Download PDFInfo
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- 238000000746 purification Methods 0.000 title claims abstract description 79
- 239000000463 material Substances 0.000 title claims abstract description 59
- 239000011258 core-shell material Substances 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims description 22
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 116
- 239000002245 particle Substances 0.000 claims abstract description 107
- 239000010409 thin film Substances 0.000 claims abstract description 78
- 229910001233 yttria-stabilized zirconia Inorganic materials 0.000 claims abstract description 67
- 239000007789 gas Substances 0.000 claims description 68
- 229910000510 noble metal Inorganic materials 0.000 claims description 48
- 239000010408 film Substances 0.000 claims description 44
- 239000002243 precursor Substances 0.000 claims description 39
- 229910052703 rhodium Inorganic materials 0.000 claims description 19
- 239000010948 rhodium Substances 0.000 claims description 19
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 19
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 18
- 238000005229 chemical vapour deposition Methods 0.000 claims description 13
- 238000003756 stirring Methods 0.000 claims description 8
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 6
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 6
- 229910052763 palladium Inorganic materials 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 239000000843 powder Substances 0.000 description 45
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 40
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- 230000000052 comparative effect Effects 0.000 description 17
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 10
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- 230000005764 inhibitory process Effects 0.000 description 6
- 238000009834 vaporization Methods 0.000 description 6
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- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000010970 precious metal Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- 239000007983 Tris buffer Substances 0.000 description 3
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- 229910052786 argon Inorganic materials 0.000 description 3
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- 238000003917 TEM image Methods 0.000 description 2
- CUJRVFIICFDLGR-UHFFFAOYSA-N acetylacetonate Chemical compound CC(=O)[CH-]C(C)=O CUJRVFIICFDLGR-UHFFFAOYSA-N 0.000 description 2
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- 238000009616 inductively coupled plasma Methods 0.000 description 2
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- 239000011812 mixed powder Substances 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 2
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- 238000001179 sorption measurement Methods 0.000 description 2
- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 2
- XBIUWALDKXACEA-UHFFFAOYSA-N 3-[bis(2,4-dioxopentan-3-yl)alumanyl]pentane-2,4-dione Chemical compound CC(=O)C(C(C)=O)[Al](C(C(C)=O)C(C)=O)C(C(C)=O)C(C)=O XBIUWALDKXACEA-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
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- 238000001035 drying Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
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- 239000010453 quartz Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
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- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
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Abstract
Description
本発明は、表面がアルミナ系酸化物で被覆されたイットリア安定化ジルコニア系酸化物粒子を含有するコアシェル型酸化物材料、その製造方法、それを用いた排ガス浄化用触媒、及び排ガス浄化方法に関する。 The present invention relates to a core-shell type oxide material containing yttria-stabilized zirconia-based oxide particles coated on the surface with an alumina-based oxide, a method for producing the same, an exhaust gas purification catalyst using the same, and an exhaust gas purification method.
自動車の内燃機関等から排出される、窒素酸化物を含有するガスを浄化するための排ガス浄化用触媒として、ロジウム等の貴金属をアルミナ等の金属酸化物からなる担体に担持した触媒が知られている。しかしながら、ロジウム等の貴金属をアルミナ担体に担持した排ガス浄化用触媒は、高温酸化雰囲気下において排ガス浄化性能が著しく低下するという問題があり、触媒の耐熱性を向上させるために、金属酸化物担体としてジルコニア担体を用いることが提案されている。 As an exhaust gas purification catalyst for purifying a nitrogen oxide-containing gas discharged from an internal combustion engine or the like of a car, a catalyst is known in which a noble metal such as rhodium is supported on a carrier composed of a metal oxide such as alumina. There is. However, a catalyst for exhaust gas purification in which a noble metal such as rhodium is supported on an alumina support has a problem that the exhaust gas purification performance is significantly reduced in a high temperature oxidizing atmosphere, and in order to improve the heat resistance of the catalyst It has been proposed to use a zirconia support.
例えば、特開２００７−９８２５１号公報（特許文献１）には、ジルコニア粒子及び前記ジルコニア粒子を被覆している特定の金属Ａの酸化物を有する触媒担体にロジウムが担持されている排ガス浄化用触媒が記載されており、前記金属Ａとしてアルミニウムが例示されている。また、特許文献１には、前記触媒担体の製造方法として、前記金属Ａの塩の溶液にジルコニア粒子を分散させ、この金属Ａの水酸化物等をジルコニア粒子上に堆積させ、乾燥及び焼結する方法（いわゆる、液相法）が記載されている。 For example, Japanese Patent Application Laid-Open No. 2007-98251 (Patent Document 1) discloses a catalyst for exhaust gas purification in which rhodium is supported on a catalyst support having zirconia particles and a specific metal A oxide coating the zirconia particles. Is described, and as the metal A, aluminum is exemplified. Further, in Patent Document 1, as a method for producing the catalyst carrier, zirconia particles are dispersed in a solution of the salt of the metal A, a hydroxide of the metal A is deposited on the zirconia particles, and drying and sintering are performed. Methods (so-called liquid phase methods) are described.
しかしながら、ジルコニア粒子の表面を液相法により金属酸化物で被覆すると、金属酸化物が凝集しやすく、ジルコニア粒子の表面に均一に金属酸化物膜を形成することは困難であり、また、形成される金属酸化物膜も厚膜になるため、得られる排ガス浄化用触媒のＮＯｘ浄化性能が必ずしも十分に高いものではなかった。 However, when the surface of the zirconia particles is coated with a metal oxide by a liquid phase method, the metal oxide tends to aggregate, and it is difficult to form a metal oxide film uniformly on the surface of the zirconia particles, and Since the metal oxide film also becomes thick, the NOx purification performance of the resulting exhaust gas purification catalyst is not necessarily high enough.
本発明は、上記従来技術の有する課題に鑑みてなされたものであり、優れたＮＯｘ浄化性能を有する排ガス浄化用触媒を得ることが可能な酸化物材料、その製造方法、それを用いた排ガス浄化用触媒、及び排ガス浄化方法を提供することを目的とする。 The present invention has been made in view of the problems of the prior art, and an oxide material capable of obtaining an exhaust gas purification catalyst having excellent NOx purification performance, a method for producing the same, and exhaust gas purification using the same It is an object of the present invention to provide a catalyst for exhaust gas and an exhaust gas purification method.
本発明者らは、上記目的を達成すべく鋭意研究を重ねた結果、ジルコニア系酸化物粒子を攪拌しながら、アルミナ前駆体を用いて化学気相成長法により前記ジルコニア系酸化物粒子の表面にアルミナ系酸化物薄膜を形成することによって、前記ジルコニア系酸化物粒子の表面の３０％以上を膜厚の薄いアルミナ系酸化物薄膜で被覆することができ、得られる排ガス浄化用触媒が優れたＮＯｘ浄化性能を示すことを見出し、本発明を完成するに至った。 As a result of intensive studies to achieve the above object, the present inventors found that, while stirring the zirconia-based oxide particles, the surface of the zirconia-based oxide particles is grown by chemical vapor deposition using an alumina precursor. By forming an alumina-based oxide thin film, 30% or more of the surface of the zirconia-based oxide particles can be coated with a thin alumina-based oxide thin film, and the resulting exhaust gas purification catalyst is excellent in NOx It has been found that the purification performance is shown, and the present invention has been completed.
すなわち、本発明のコアシェル型酸化物材料は、平均粒子径が０．１〜５０μｍのイットリア安定化ジルコニア系酸化物粒子からなるコアと、該コアの表面の３０％以上を被覆している、平均膜厚が１〜２０ｎｍのアルミナ系酸化物薄膜からなるシェルとを備えていることを特徴とするものである。 That is, the core-shell type oxide material of the present invention has a core comprising yttria-stabilized zirconia-based oxide particles having an average particle size of 0.1 to 50 μm and an average of 30% or more of the surface of the core. And a shell made of an alumina-based oxide thin film having a thickness of 1 to 20 nm.
このような本発明のコアシェル型酸化物材料においては、前記アルミナ系酸化物薄膜の含有量が前記イットリア安定化ジルコニア系酸化物粒子１００質量部に対して０．１〜１質量部であることが好ましい。 In such a core-shell type oxide material of the present invention, the content of the alumina-based oxide thin film is 0.1 to 1 part by mass with respect to 100 parts by mass of the yttria-stabilized zirconia-based oxide particle. preferable.
また、本発明のコアシェル型酸化物材料の製造方法は、平均粒子径が０．１〜５０μｍのイットリア安定化ジルコニア系酸化物粒子を攪拌しながら、アルミナ前駆体を用いて化学気相成長法により、前記イットリア安定化ジルコニア系酸化物粒子からなるコアの表面の３０％以上に平均膜厚が１〜２０ｎｍのアルミナ系酸化物薄膜からなるシェルを形成することを特徴とする。 Moreover, the method for producing a core-shell type oxide material of the present invention is carried out by a chemical vapor deposition method using an alumina precursor while stirring yttria-stabilized zirconia-based oxide particles having an average particle diameter of 0.1 to 50 μm. A shell formed of an alumina-based oxide thin film having an average film thickness of 1 to 20 nm is formed on 30% or more of the surface of the core made of the yttria-stabilized zirconia-based oxide particles.
このような本発明のコアシェル型酸化物材料の製造方法においては、前記アルミナ前駆体が有機アルミニウム錯体であることが好ましい。 In such a method of producing a core-shell type oxide material of the present invention, the alumina precursor is preferably an organoaluminum complex.
さらに、本発明の排ガス浄化用触媒は、前記本発明のコアシェル型酸化物材料と、該コアシェル型酸化物材料の表面に接触している、ロジウム、パラジウム及び白金からなる群から選択される少なくとも１種の貴金属とを備えていることを特徴とするものである。また、本発明の排ガス浄化方法は、前記本発明の排ガス浄化用触媒に、窒素酸化物を含有する排ガスを接触せしめることを特徴とする。 Furthermore, the exhaust gas purification catalyst of the present invention comprises the core-shell type oxide material of the present invention and at least one selected from the group consisting of rhodium, palladium and platinum in contact with the surface of the core-shell type oxide material. It is characterized in that it is provided with a kind of noble metal. The exhaust gas purification method of the present invention is characterized in that the exhaust gas containing nitrogen oxide is brought into contact with the exhaust gas purification catalyst of the present invention.
なお、本発明の排ガス浄化用触媒が優れたＮＯｘ浄化性能を有する理由は必ずしも定かではないが、本発明者らは以下のように推察する。すなわち、アルミナ系酸化物薄膜上に担持されたロジウム等の貴金属粒子は、電子供与性が高いアルミナとの相互作用が強いため、貴金属粒子の移動やシンタリングが抑制されるが、貴金属−Ｏ−Ａｌ相互作用が貴金属のメタル化（酸化された貴金属の還元）を阻害する傾向にある。また、ジルコニア系酸化物粒子上に担持された貴金属粒子は、電子供与性が弱いジルコニアとの相互作用が弱いため、貴金属のメタル化（酸化された貴金属の還元）は促進されるが、貴金属粒子の移動やシンタリングも進行しやすい傾向にある。 The reason why the exhaust gas purification catalyst of the present invention has excellent NOx purification performance is not necessarily clear, but the present inventors speculate as follows. That is, since noble metal particles such as rhodium supported on the alumina-based oxide thin film have strong interaction with alumina having high electron donating ability, movement and sintering of the noble metal particles are suppressed, but noble metal-O- Al interaction tends to inhibit the metalation of noble metals (reduction of oxidized noble metals). Further, since noble metal particles supported on the zirconia-based oxide particles have weak interaction with zirconia having weak electron donating ability, metalation of the noble metal (reduction of oxidized noble metal) is promoted, but the noble metal particles Movement and sintering also tend to progress.
本発明のコアシェル型酸化物材料に貴金属を接触させた触媒においては、図１に示すように、アルミナ系酸化物薄膜１の被覆率が大きいため、貴金属粒子２はアルミナ系酸化物薄膜１に接触しやすく、貴金属粒子２の移動やシンタリングが抑制され、また、アルミナ系酸化物薄膜１の厚さが薄いため、貴金属−Ｏ−Ａｌ相互作用による貴金属のメタル化の阻害がジルコニアによって抑制されることから、優れたＮＯｘ浄化性能が発現すると推察される。 In the catalyst in which a noble metal is brought into contact with the core-shell type oxide material of the present invention, as shown in FIG. 1, the noble metal particles 2 are in contact with the alumina-based oxide thin film 1 because the coverage of the alumina-based oxide thin film 1 is large. Easily, migration and sintering of the noble metal particles 2 are suppressed, and since the thickness of the alumina-based oxide thin film 1 is thin, the inhibition of the metalization of the noble metal by the noble metal-O-Al interaction is suppressed by the zirconia From this, it is presumed that an excellent NOx purification performance is exhibited.
一方、液相法により製造した従来のコアシェル型酸化物材料にロジウム等の貴金属を接触させた触媒においては、図２に示すように、アルミナ系酸化物薄膜１の被覆率が小さいため、貴金属粒子２がアルミナ系酸化物薄膜１に接触しにくく、ジルコニア系酸化物粒子３上の貴金属粒子２の移動やシンタリングが進行しやすく、また、アルミナ系酸化物薄膜１の厚さが厚いため、アルミナ系酸化物薄膜１に接触している貴金属のメタル化の阻害がジルコニアによって十分に抑制されないことから、ＮＯｘ浄化性能が十分に向上しないと推察される。 On the other hand, in a catalyst in which a noble metal such as rhodium is brought into contact with a conventional core-shell type oxide material manufactured by a liquid phase method, as shown in FIG. 2 is difficult to contact with the alumina-based oxide thin film 1, migration and sintering of the noble metal particles 2 on the zirconia-based oxide particles 3 are likely to proceed, and the thickness of the alumina-based oxide thin film 1 is large. Since inhibition of the metalization of the noble metal in contact with the oxide thin film 1 is not sufficiently suppressed by the zirconia, it is presumed that the NOx purification performance is not sufficiently improved.
本発明によれば、優れたＮＯｘ浄化性能を有する排ガス浄化用触媒を得ることが可能となる。 According to the present invention, it is possible to obtain an exhaust gas purification catalyst having excellent NOx purification performance.
以下、本発明をその好適な実施形態に即して詳細に説明する。 Hereinafter, the present invention will be described in detail in line with its preferred embodiments.
〔コアシェル型酸化物材料〕
先ず、本発明のコアシェル型酸化物材料について説明する。本発明のコアシェル型酸化物材料は、平均粒子径が０．１〜５０μｍのイットリア安定化ジルコニア系酸化物粒子からなるコアと、該コアの表面の３０％以上を被覆している、平均膜厚が１〜２０ｎｍのアルミナ系酸化物薄膜からなるシェルとを備えるものである。
[Core-shell type oxide material]
First, the core-shell type oxide material of the present invention will be described. The core-shell type oxide material of the present invention has a core comprising yttria-stabilized zirconia-based oxide particles having an average particle diameter of 0.1 to 50 μm and an average film thickness covering 30% or more of the surface of the core. And a shell comprising an alumina-based oxide thin film of 1 to 20 nm.
（イットリア安定化ジルコニア系酸化物粒子）
本発明のコアシェル型酸化物材料は、イットリア安定化ジルコニア系酸化物粒子（以下、「ＹＳＺ系酸化物粒子」と略す）からなるコアを備えるものである。このようなＹＳＺ系酸化物粒子からなるコアを備えるコアシェル型酸化物材料を触媒担体として用いることによって、後述する排ガス浄化用触媒において、触媒成分である貴金属のメタル化が促進され、優れたＮＯｘ浄化性能を得ることが可能となる。
(Yttria stabilized zirconia-based oxide particles)
The core-shell type oxide material of the present invention is provided with a core composed of yttria-stabilized zirconia-based oxide particles (hereinafter, abbreviated as "YSZ-based oxide particles"). By using a core-shell type oxide material having a core composed of such YSZ-based oxide particles as a catalyst carrier, metalization of a noble metal as a catalyst component is promoted in an exhaust gas purification catalyst described later, and excellent NOx purification It is possible to obtain performance.
本発明における前記ＹＳＺ系酸化物粒子の平均粒子径は０．１〜５０μｍである。ＹＳＺ系酸化物粒子の平均粒子径が前記下限未満になると、シンタリングが起こりやすくなり、耐熱性が低下する。また、前記ＹＳＺ系酸化物粒子の表面をアルミナ系酸化物薄膜で均一に被覆することが困難となる。他方、前記ＹＳＺ系酸化物粒子の平均粒子径が前記上限を超えると、コアシェル型酸化物材料の平均粒子径が排ガス浄化用触媒担体として一般的な平均粒子径から大きく逸脱し、スラリーコートの際に不具合が生じる場合がある。このようなＹＳＺ系酸化物粒子の平均粒子径としては、耐熱性が高く、コーティングがしやすく、実用触媒の担体として好ましい平均粒子径であるという観点から、０．５〜１０μｍが好ましい。 The average particle diameter of the YSZ-based oxide particles in the present invention is 0.1 to 50 μm. When the average particle size of the YSZ-based oxide particles is less than the above lower limit, sintering easily occurs and the heat resistance is lowered. In addition, it becomes difficult to uniformly coat the surface of the YSZ-based oxide particles with an alumina-based oxide thin film. On the other hand, when the average particle size of the YSZ-based oxide particles exceeds the upper limit, the average particle size of the core-shell type oxide material largely deviates from the average particle size generally used as a catalyst carrier for exhaust gas purification. Problems may occur. The average particle diameter of such YSZ-based oxide particles is preferably 0.5 to 10 μm from the viewpoint of high heat resistance, easy coating, and a preferable average particle diameter as a carrier for practical catalysts.
このようなＹＳＺ系酸化物粒子としては特に制限はなく、従来公知の方法で調製したものや市販のものを用いることができる。 There is no restriction | limiting in particular as such a YSZ type oxide particle, What was prepared by the conventionally well-known method, and a commercially available thing can be used.
（アルミナ系酸化物薄膜）
本発明のコアシェル型酸化物材料は、前記ＹＳＺ系酸化物粒子からなるコアの表面を被覆しているアルミナ系酸化物薄膜からなるシェルを備えるものである。このようなアルミナ系酸化物薄膜からなるシェルを備えるコアシェル型酸化物材料を触媒担体として用いることによって、後述する排ガス浄化用触媒において、触媒成分である貴金属の移動やシンタリングを抑制することができ、優れたＮＯｘ浄化性能を得ることが可能となる。また、このようなアルミナ系酸化物薄膜は、多孔質であることが好ましい。これにより、触媒成分である貴金属の移動やシンタリングを抑制することができ、また、アルミナ系酸化物薄膜内における排ガスの拡散性を十分に確保することができる。
(Alumina-based oxide thin film)
The core-shell type oxide material of the present invention comprises a shell comprising an alumina-based oxide thin film covering the surface of the core comprising the YSZ-based oxide particles. By using a core-shell type oxide material having a shell made of such an alumina-based oxide thin film as a catalyst carrier, it is possible to suppress migration or sintering of a noble metal as a catalyst component in an exhaust gas purification catalyst described later. It is possible to obtain excellent NOx purification performance. Moreover, such an alumina-based oxide thin film is preferably porous. Thereby, the migration and sintering of the noble metal as the catalyst component can be suppressed, and the diffusivity of the exhaust gas in the alumina-based oxide thin film can be sufficiently secured.
本発明における前記アルミナ系酸化物薄膜の平均膜厚は１〜２０ｎｍである。アルミナ系酸化物薄膜の平均膜厚が前記下限未満になると、貴金属の移動やシンタリングが十分に抑制されず、ＮＯｘ浄化性能が十分に向上せず、他方、前記上限を超えると、ＹＳＺ系酸化物粒子の作用が十分に発現せず、後述する排ガス浄化用触媒において、貴金属−Ｏ−Ａｌ相互作用による貴金属のメタル化の阻害がジルコニアによって十分に抑制されず、ＮＯｘ浄化性能が十分に向上しない。このようなアルミナ系酸化物薄膜の平均膜厚としては、貴金属の移動やシンタリングが十分に抑制され、また、貴金属−Ｏ−Ａｌ相互作用による貴金属のメタル化の阻害がジルコニアによって十分に抑制されることによって、ＮＯｘ浄化性能が更に向上するという観点から、２〜１０ｎｍが好ましい。なお、本発明において、アルミナ系酸化物薄膜の平均膜厚は、コア表面全体を基準として（すなわち、被覆されていない領域を含めて）算出されるものではなく、コア表面の被覆されている領域を基準として（すなわち、被覆されていない領域を除外して）算出されるアルミナ系酸化物薄膜の平均膜厚である。 The average film thickness of the alumina-based oxide thin film in the present invention is 1 to 20 nm. When the average film thickness of the alumina-based oxide thin film is less than the above lower limit, the movement and sintering of the noble metal are not sufficiently suppressed, and the NOx purification performance is not sufficiently improved. In the exhaust gas purification catalyst described later, the inhibition of the metalization of the noble metal by the noble metal-O-Al interaction is not sufficiently suppressed by the zirconia and the NOx purification performance is not sufficiently improved in the catalyst for exhaust gas purification described later . With respect to the average film thickness of such an alumina-based oxide thin film, migration and sintering of the noble metal are sufficiently suppressed, and inhibition of metalization of the noble metal by the noble metal-O-Al interaction is sufficiently suppressed by the zirconia. 2 to 10 nm is preferable from the viewpoint of further improving the NOx purification performance. In the present invention, the average film thickness of the alumina-based oxide thin film is not calculated on the basis of the entire core surface (that is, including the uncovered region), but the covered region of the core surface The average film thickness of the alumina-based oxide thin film is calculated on the basis of (ie, excluding the uncoated area).
本発明のコアシェル型酸化物材料においては、前記コアの表面の３０％以上が前記アルミナ系酸化物薄膜で被覆されている。アルミナ系酸化物薄膜の被覆率が前記下限未満になると、後述する排ガス浄化用触媒において、触媒成分である貴金属がアルミナ系酸化物薄膜と接触しにくくなり、貴金属の移動やシンタリングが十分に抑制されず、ＮＯｘ浄化性能が十分に向上しない。このようなアルミナ系酸化物薄膜の被覆率としては、触媒成分である貴金属がアルミナ系酸化物薄膜と接触しやすく、貴金属の移動やシンタリングが十分に抑制され、ＮＯｘ浄化性能がより向上するという観点から、４０％以上が好ましい。なお、アルミナ系酸化物薄膜の被覆率の上限としては１００％以下であり、８０％以下が好ましい。なお、本発明のコアシェル型酸化物材料においては、アルミナ系酸化物薄膜の厚さが薄いため、コアの全表面がアルミナ系酸化物薄膜で被覆されていても、前記ＹＳＺ系酸化物粒子による作用は発現する。 In the core-shell type oxide material of the present invention, 30% or more of the surface of the core is coated with the alumina-based oxide thin film. When the coverage of the alumina-based oxide thin film is less than the above lower limit, in the exhaust gas purification catalyst described later, the noble metal as the catalyst component is less likely to contact the alumina-based oxide thin film, and the movement and sintering of the noble metal is sufficiently suppressed. And the NOx purification performance is not sufficiently improved. With regard to the coverage of such an alumina-based oxide thin film, it is said that the noble metal as the catalyst component easily contacts the alumina-based oxide thin film, migration and sintering of the noble metal are sufficiently suppressed, and the NOx purification performance is further improved. From a viewpoint, 40% or more is preferable. The upper limit of the coverage of the alumina-based oxide thin film is 100% or less, preferably 80% or less. In the core-shell type oxide material of the present invention, since the thickness of the alumina-based oxide thin film is thin, even if the entire surface of the core is covered with the alumina-based oxide thin film, the action by the YSZ-based oxide particles is Is expressed.
また、本発明のコアシェル型酸化物材料においては、前記アルミナ系酸化物薄膜の含有量が前記ＹＳＺ系酸化物粒子１００質量部に対して０．１〜１質量部が好ましく、０．１〜０．５質量部がより好ましく、０．２〜０．４質量部が特に好ましい。アルミナ系酸化物薄膜の含有量が前記範囲内にあると、前記範囲の平均膜厚のアルミナ系酸化物薄膜によって前記範囲の被覆率でコアの表面を被覆することができる。一方、アルミナ系酸化物薄膜の含有量が前記下限未満になると、アルミナ系酸化物薄膜の被覆率が小さくなったり、平均膜厚が薄くなったりするため、後述する排ガス浄化用触媒において、貴金属の移動やシンタリングが十分に抑制されず、ＮＯｘ浄化性能が十分に向上しない傾向にあり、他方、前記上限を超えると、アルミナ系酸化物薄膜の平均膜厚が厚くなりすぎ、ＹＳＺ系酸化物粒子の作用が十分に発現せず、後述する排ガス浄化用触媒において、貴金属−Ｏ−Ａｌ相互作用による貴金属のメタル化の阻害がジルコニアによって十分に抑制されず、ＮＯｘ浄化性能が十分に向上しない傾向にある。 Further, in the core-shell type oxide material of the present invention, the content of the alumina-based oxide thin film is preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the YSZ-based oxide particle, and 0.1 to 0 The amount is more preferably 0.5 parts by mass, and particularly preferably 0.2 to 0.4 parts by mass. When the content of the alumina-based oxide thin film is in the above range, the surface of the core can be coated with the coverage in the above-mentioned range by the alumina-based oxide thin film having the average film thickness in the above-mentioned range. On the other hand, when the content of the alumina-based oxide thin film is less than the above lower limit, the coverage of the alumina-based oxide thin film becomes small or the average film thickness becomes thin. Movement and sintering are not sufficiently suppressed, and NOx purification performance tends not to be sufficiently improved. On the other hand, when the above upper limit is exceeded, the average film thickness of the alumina-based oxide thin film becomes too thick, and YSZ-based oxide particles In the exhaust gas purification catalyst described later, the inhibition of the metalization of the noble metal by the noble metal-O-Al interaction is not sufficiently suppressed by the zirconia and the NOx purification performance tends not to be sufficiently improved. is there.
〔コアシェル型酸化物材料の製造方法〕
次に、本発明のコアシェル型酸化物材料の製造方法について説明する。本発明のコアシェル型酸化物材料の製造方法は、平均粒子径が０．１〜５０μｍのイットリア安定化ジルコニア系酸化物粒子を攪拌しながら、アルミナ前駆体を用いて化学気相成長法により、前記イットリア安定化ジルコニア系酸化物粒子からなるコアの表面の３０％以上に平均膜厚が１〜２０ｎｍのアルミナ系酸化物薄膜からなるシェルを形成する方法である。
[Method of producing core-shell type oxide material]
Next, the method for producing the core-shell type oxide material of the present invention will be described. The method for producing a core-shell type oxide material according to the present invention is the chemical vapor deposition method using an alumina precursor while stirring yttria-stabilized zirconia-based oxide particles having an average particle diameter of 0.1 to 50 μm. This is a method of forming a shell of an alumina-based oxide thin film having an average film thickness of 1 to 20 nm on 30% or more of the surface of a core composed of yttria-stabilized zirconia-based oxide particles.
本発明のコアシェル型酸化物材料の製造方法に用いられるイットリア安定化ジルコニア系酸化物粒子は、前記本発明のコアシェル型酸化物材料の説明において記載したイットリア安定化ジルコニア系酸化物粒子（ＹＳＺ系酸化物粒子）である。 The yttria-stabilized zirconia-based oxide particles used in the method for producing a core-shell type oxide material according to the present invention are the yttria-stabilized zirconia-based oxide particles described in the description of the core-shell type oxide material according to the present invention Object particle).
本発明に用いられるアルミナ前駆体としては化学気相成長法によるアルミナ系酸化物薄膜の形成に用いることが可能なものであれば特に制限はなく、例えば、有機アルミニウム錯体（トリス（ジピバロイルメタナト）アルミニウム（Ａｌ（ＤＰＭ）３）、トリス（２，４−ペンタンジオナト）アルミニウム（アルミニウムアセチルアセトナト、Ａｌ（ａｃａｃ）３）、トリメチルアルミニウム（ＴＭＡ）等）が挙げられる。これらのアルミナ前駆体は１種を単独で使用しても２種以上を併用してもよい。また、これらのアルミナ前駆体の中でも、入手しやすく、大気中での安定性が高く、取扱いやすく、気化分解温度が低いという観点から、Ａｌ（ＤＰＭ）３、Ａｌ（ａｃａｃ）３が好ましく、Ａｌ（ＤＰＭ）３がより好ましい。 The alumina precursor used in the present invention is not particularly limited as long as it can be used for forming an alumina-based oxide thin film by chemical vapor deposition, and, for example, an organoaluminum complex (tris (dipivaloylme Tanato) aluminum (Al (DPM) 3 ), tris (2,4-pentanedionato) aluminum (aluminum acetylacetonate, Al (acac) 3 ), trimethylaluminum (TMA), etc. may be mentioned. These alumina precursors may be used alone or in combination of two or more. Further, among these alumina precursors, Al (DPM) 3 and Al (acac) 3 are preferable from the viewpoint of easy availability, high stability in the atmosphere, easy handling, and low vaporization decomposition temperature. (DPM) 3 is more preferred.
本発明のコアシェル型酸化物材料の製造方法においては、前記ＹＳＺ系酸化物粒子を攪拌しながら、前記アルミナ前駆体を用いて化学気相成長法により、ＹＳＺ系酸化物粒子からなるコアの表面にアルミナ系酸化物薄膜からなるシェルを形成する。具体的には、回転式成膜室と加熱炉と前駆体気化部を備えるＣＶＤ装置の回転式成膜室内にＹＳＺ系酸化物粒子を投入し、前駆体ホルダーにアルミナ前駆体を投入する。回転式成膜室を加熱炉で所定の温度に加熱しながら回転させてＹＳＺ系酸化物粒子を加熱攪拌する。これに、前駆体ホルダーから前駆体気化部を通して所定の温度に加熱して気化させたアルミナ前駆体を、所定の温度に加熱した酸素含有ガス（例えば、酸素と不活性ガスとの混合ガス）とともに導入する。これにより、前記ＹＳＺ系酸化物粒子の表面の少なくとも一部にアルミナ前駆体が付着し、このアルミナ前駆体がアルミナ系酸化物に変換されるため、前記ＹＳＺ系酸化物粒子の表面の少なくとも一部にアルミナ系酸化物薄膜が形成されたコアシェル型酸化物材料が得られる。 In the method for producing a core-shell type oxide material according to the present invention, the surface of the core made of YSZ-based oxide particles is formed by chemical vapor deposition using the alumina precursor while stirring the YSZ-based oxide particles. A shell is formed of an alumina-based oxide thin film. Specifically, YSZ-based oxide particles are introduced into a rotary film formation chamber of a CVD apparatus including a rotary film formation chamber, a heating furnace, and a precursor vaporization unit, and an alumina precursor is charged into a precursor holder. The rotary film forming chamber is rotated while being heated to a predetermined temperature by a heating furnace to heat and stir the YSZ-based oxide particles. Further, the alumina precursor which is vaporized by heating from the precursor holder to the predetermined temperature through the precursor vaporization unit is combined with the oxygen-containing gas (eg, mixed gas of oxygen and inert gas) heated to the predetermined temperature. Introduce. Thereby, an alumina precursor adheres to at least a part of the surface of the YSZ-based oxide particle, and this alumina precursor is converted to an alumina-based oxide, so at least a part of the surface of the YSZ-based oxide particle A core-shell type oxide material having an alumina-based oxide thin film formed thereon is obtained.
アルミナ前駆体の導入量としては、ＹＳＺ系酸化物粒子１００質量部に対して、５０〜２００質量部が好ましく、５０〜１５０質量部がより好ましく、５０〜１００質量部が特に好ましい。アルミナ前駆体の導入量が前記下限未満になると、アルミナ系酸化物薄膜の被覆率が小さくなったり、平均膜厚が薄くなったりするため、後述する排ガス浄化用触媒において、貴金属の移動やシンタリングが十分に抑制されず、ＮＯｘ浄化性能が十分に向上しない傾向にあり、他方、前記上限を超えると、アルミナ系酸化物薄膜の平均膜厚が厚くなりすぎ、ＹＳＺ系酸化物粒子の作用が十分に発現せず、後述する排ガス浄化用触媒において、貴金属−Ｏ−Ａｌ相互作用による貴金属のメタル化の阻害がジルコニアによって十分に抑制されず、ＮＯｘ浄化性能が十分に向上しない傾向にある。 The introduction amount of the alumina precursor is preferably 50 to 200 parts by mass, more preferably 50 to 150 parts by mass, and particularly preferably 50 to 100 parts by mass with respect to 100 parts by mass of the YSZ-based oxide particles. When the introduction amount of the alumina precursor is less than the above lower limit, the coverage of the alumina-based oxide thin film becomes small and the average film thickness becomes thin. Therefore, in the exhaust gas purification catalyst described later, movement and sintering of noble metals Is not sufficiently suppressed, and the NOx purification performance tends not to be sufficiently improved. On the other hand, when the upper limit is exceeded, the average film thickness of the alumina-based oxide thin film becomes too thick, and the action of the YSZ-based oxide particles is sufficiently In the exhaust gas purification catalyst described later, the inhibition of the metalization of the noble metal due to the noble metal-O-Al interaction is not sufficiently suppressed by the zirconia, and the NOx purification performance tends not to be sufficiently improved.
アルミナ前駆体の加熱温度としては、１９０〜２４０℃が好ましく、１９５〜２２０℃がより好ましく、２００〜２１５℃が特に好ましい。アルミナ前駆体の加熱温度が前記下限未満になると、アルミナ前駆体の気化速度が遅くなる傾向にあり、他方、前記上限を超えると、アルミナ前駆体の気化速度が速くなりすぎてコーティングムラが多くなる傾向にある。 As a heating temperature of an alumina precursor, 190-240 ° C is preferred, 195-220 ° C is more preferred, and 200-215 ° C is especially preferred. If the heating temperature of the alumina precursor is below the lower limit, the vaporization rate of the alumina precursor tends to be slow, while if the heating temperature exceeds the upper limit, the vaporization rate of the alumina precursor becomes too fast and coating unevenness increases. There is a tendency.
成膜温度（加熱炉による加熱温度）としては、６００〜１０００℃が好ましく、７００〜９００℃がより好ましく、７５０〜９００℃が特に好ましい。成膜温度が前記下限未満になると、アルミナ系酸化物薄膜を安定して形成できない場合があり、他方、前記上限を超えると、アルミナの結晶化が進行し、多孔性を損なう傾向にある。 As film-forming temperature (heating temperature by a heating furnace), 600-1000 degreeC is preferable, 700-900 degreeC is more preferable, and 750-900 degreeC is especially preferable. When the film forming temperature is less than the lower limit, the alumina-based oxide thin film may not be stably formed. On the other hand, when the upper limit is exceeded, crystallization of alumina proceeds and the porosity tends to be impaired.
酸素含有ガス中の酸素の割合としては、酸素／不活性ガス（体積比）で１／１０〜５／１が好ましく、１／２〜２／１がより好ましく、１／２〜１／１が特に好ましい。酸素の割合が前記下限未満になると、アルミナ前駆体の酸化反応が阻害され、十分なアルミナ系酸化物薄膜が形成されにくい傾向にあり、他方、前記上限を超えると、前記ＹＳＺ系酸化物粒子の表面にアルミナ前駆体が到達する前に、アルミナ前駆体が酸化され、均一なアルミナ系酸化物薄膜が形成されにくい傾向にある。 The ratio of oxygen in the oxygen-containing gas is preferably 1/10 to 5/1, more preferably 1/2 to 2/1, and 1/2 to 1/1 in terms of oxygen / inert gas (volume ratio). Particularly preferred. If the proportion of oxygen is less than the above lower limit, the oxidation reaction of the alumina precursor is inhibited and it tends to be difficult to form a sufficient alumina-based oxide thin film, while if it exceeds the above upper limit, the YSZ-based oxide particles Before the alumina precursor reaches the surface, the alumina precursor tends to be oxidized, making it difficult to form a uniform alumina-based oxide thin film.
酸素含有ガスの流量としては、１〜２００ｓｃｃｍが好ましく、５〜１００ｓｃｃｍがより好ましく、２０〜１００ｓｃｃｍが特に好ましい。酸素含有ガスの流量が前記下限未満になると、成膜に適した酸素濃度を達成できず、十分なアルミナ系酸化物薄膜が形成されにくい傾向にあり、他方、前記上限を超えると、前記ＹＳＺ系酸化物粒子の表面にアルミナ前駆体が到達する前に、アルミナ前駆体が酸化され、均一なアルミナ系酸化物薄膜が形成されにくい傾向にある。 The flow rate of the oxygen-containing gas is preferably 1 to 200 sccm, more preferably 5 to 100 sccm, and particularly preferably 20 to 100 sccm. If the flow rate of the oxygen-containing gas is less than the lower limit, an oxygen concentration suitable for film formation can not be achieved, and a sufficient alumina-based oxide thin film tends to be difficult to be formed. Before the alumina precursor reaches the surface of the oxide particles, the alumina precursor tends to be oxidized, making it difficult to form a uniform alumina-based oxide thin film.
成膜時の全圧（成膜室内の圧力）としては、１０〜２０００Ｐａが好ましく、５０〜１０００Ｐａがより好ましく、１００〜１０００Ｐａが特に好ましい。成膜時の全圧が前記下限未満になると、前記ＹＳＺ系酸化物粒子の表面に供給される酸素及びアルミナ前駆体の濃度が低下し、アルミナ系酸化物薄膜の成膜速度が遅くなる傾向にあり、他方、前記上限を超えると、アルミナ前駆体の配管詰まりが起こりやすくなる傾向にある。 As a total pressure at the time of film formation (pressure in the film formation chamber), 10 to 2000 Pa is preferable, 50 to 1000 Pa is more preferable, and 100 to 1000 Pa is particularly preferable. If the total pressure during film formation is less than the above lower limit, the concentration of oxygen and alumina precursor supplied to the surface of the YSZ-based oxide particles tends to decrease, and the film formation rate of the alumina-based oxide thin film tends to be slow. On the other hand, when the above upper limit is exceeded, the clogging of the alumina precursor tends to occur easily.
成膜室の回転数としては、５〜５０ｒｐｍが好ましく、１０〜３０ｒｐｍがより好ましく、１５〜２５ｒｐｍが特に好ましい。成膜室の回転数が前記下限未満になると、前記ＹＳＺ系酸化物粒子の浮遊時間が短くなり、アルミナ系酸化物薄膜の厚さが薄くなる傾向にあり、他方、前記上限を超えると、前記ＹＳＺ系酸化物粒子が凝集しやすくなり、均一なアルミナ系酸化物薄膜を形成することが困難となる傾向にある。 The number of rotations of the film forming chamber is preferably 5 to 50 rpm, more preferably 10 to 30 rpm, and particularly preferably 15 to 25 rpm. When the number of revolutions of the film forming chamber is less than the lower limit, the floating time of the YSZ-based oxide particles tends to be short and the thickness of the alumina-based oxide thin film tends to be thin. The YSZ-based oxide particles tend to aggregate, making it difficult to form a uniform alumina-based oxide thin film.
成膜時間としては、３０〜１２０分間が好ましく、４５〜９０分間がより好ましく、６０〜９０分間が特に好ましい。成膜時間が前記下限未満になると、アルミナ系酸化物薄膜の厚さが薄くなりすぎる傾向にあり、他方、前記上限を超えると、成膜したアルミナ系酸化物が凝集しやすくなる傾向にある。 As film-forming time, 30 to 120 minutes are preferable, 45 to 90 minutes are more preferable, and 60 to 90 minutes are especially preferable. If the film formation time is less than the lower limit, the thickness of the alumina-based oxide thin film tends to be too thin. On the other hand, if the upper limit is exceeded, the formed alumina-based oxide tends to aggregate.
〔排ガス浄化用触媒〕
次に、本発明の排ガス浄化用触媒について説明する。本発明の排ガス浄化用触媒は、前記本発明のコアシェル型酸化物材料と、このコアシェル型酸化物材料の表面に接触している、ロジウム、パラジウム及び白金からなる群から選択される少なくとも１種の貴金属とを備えるものである。このような排ガス浄化用触媒においては、前記コアシェル型酸化物材料により、貴金属の移動やシンタリングが抑制され、さらに、貴金属のメタル化（酸化された貴金属の還元）が促進されるため、優れたＮＯｘ浄化性能が発現される。
[Catalyst for exhaust gas purification]
Next, the exhaust gas purifying catalyst of the present invention will be described. The exhaust gas purifying catalyst of the present invention comprises the core-shell type oxide material of the present invention and at least one member selected from the group consisting of rhodium, palladium and platinum in contact with the surface of the core-shell type oxide material. And a precious metal. In such an exhaust gas purification catalyst, the core-shell type oxide material suppresses migration and sintering of precious metals, and further promotes metalation of the precious metals (reduction of oxidized precious metals). NOx purification performance is exhibited.
貴金属の担持量としては、前記コアシェル型酸化物材料１００質量部に対して、０．０１〜１質量部が好ましく、０．０２〜０．５質量部がより好ましく、０．０５〜０．２質量部が特に好ましい。貴金属の担持量が前記下限未満になると、十分なＮＯｘ浄化性能が発現しない場合があり、他方、前記上限を超えると、コスト増大となる上に、貴金属のシンタリングが起こりやすくなる傾向にある。 The loading amount of the noble metal is preferably 0.01 to 1 part by mass, more preferably 0.02 to 0.5 parts by mass, with respect to 100 parts by mass of the core-shell type oxide material, and 0.05 to 0.2 Parts by weight are particularly preferred. When the supported amount of the noble metal is less than the lower limit, sufficient NOx purification performance may not be exhibited. On the other hand, when the upper limit is exceeded, the cost increases and the sintering of the noble metal tends to occur easily.
貴金属の平均粒子径としては１〜３．５ｎｍが好ましく、１〜３．２ｎｍがより好ましく、１〜３．０ｎｍが特に好ましい。貴金属の平均粒子径が前記下限未満になると、貴金属がシンタリングしやすく、また、貴金属が前記コアシェル型酸化物材料に埋没しやすくなる傾向にあり、他方、前記上限を超えると、ＮＯｘ浄化性能（特に、低温でのＮＯｘ浄化性能）が低下しやすい傾向にある。 The average particle size of the noble metal is preferably 1 to 3.5 nm, more preferably 1 to 3.2 nm, and particularly preferably 1 to 3.0 nm. When the average particle diameter of the noble metal is less than the lower limit, the noble metal tends to be sintered and the noble metal tends to be easily buried in the core-shell type oxide material, and when the upper limit is exceeded, NOx purification performance ( In particular, the NOx purification performance at low temperatures tends to decrease.
このような本発明の排ガス浄化用触媒の製造方法としては、前記コアシェル型酸化物材料に貴金属を担持できる方法であれば特に制限はなく、例えば、貴金属の前駆体を含有する溶液に前記コアシェル型酸化物材料を浸漬して貴金属の前駆体を前記コアシェル型酸化物材料に付着させた後、蒸発乾固させることによって貴金属担持コアシェル型酸化物材料を調製し、これを必要に応じて焼成することによって本発明の排ガス浄化用触媒を得ることができる。 There is no particular limitation on such a method for producing the exhaust gas purifying catalyst of the present invention as long as a noble metal can be supported on the core-shell type oxide material, and, for example, the core-shell type in a solution containing a noble metal precursor. Preparation of a noble metal-supported core-shell oxide material by immersing an oxide material to attach a precursor of a noble metal to the core-shell oxide material, and evaporating it to dryness, and calcining it as needed Thus, the exhaust gas purifying catalyst of the present invention can be obtained.
〔排ガス浄化方法〕
次に、本発明の排ガス浄化方法について説明する。本発明の排ガス浄化方法は、前記本発明の排ガス浄化用触媒に、窒素酸化物を含有する排ガスを接触せしめる方法である。これにより、前記排ガス中の窒素酸化物が分解除去される。
[Exhaust gas purification method]
Next, the exhaust gas purification method of the present invention will be described. The exhaust gas purification method of the present invention is a method of bringing the exhaust gas containing nitrogen oxide into contact with the exhaust gas purification catalyst of the present invention. Thereby, the nitrogen oxides in the exhaust gas are decomposed and removed.
前記本発明の排ガス浄化用触媒と前記排ガスとを接触させる際の温度（接触温度）としては、４００〜１０００℃が好ましく、５００〜８００℃がより好ましく、５００〜７００℃が特に好ましい。接触温度が前記下限未満になると、貴金属のメタル化が十分に進行せず、十分なＮＯｘ浄化性能が得られない傾向にあり、他方、前記上限を超えると、シンタリングによる熱劣化が起こる傾向にある。 As temperature (contact temperature) at the time of making the catalyst for exhaust gas purification of the present invention and the above-mentioned exhaust gas contact, 400-1000 ° C is preferred, 500-800 ° C is more preferred, and 500-700 ° C is especially preferred. If the contact temperature is below the lower limit, metallization of the noble metal does not proceed sufficiently, and a sufficient NOx purification performance tends to not be obtained. On the other hand, if the upper limit is exceeded, thermal degradation due to sintering tends to occur. is there.
以下、実施例及び比較例に基づいて本発明をより具体的に説明するが、本発明は以下の実施例に限定されるものではない。なお、実施例及び比較例で使用したイットリア安定化ジルコニア系酸化物粒子の平均粒子径は以下の方法により測定した。 Hereinafter, the present invention will be more specifically described based on examples and comparative examples, but the present invention is not limited to the following examples. The average particle diameter of the yttria-stabilized zirconia-based oxide particles used in Examples and Comparative Examples was measured by the following method.
＜イットリア安定化ジルコニア系酸化物粒子の平均粒子径＞
イットリア安定化ジルコニア系酸化物粒子の平均粒子径は、レーザー散乱式粒子径分布測定装置（日機装株式会社製「ＭＴ３３００ＥＸ」）を用いた粒子径分布解析により求めた。
<Average particle diameter of yttria-stabilized zirconia-based oxide particles>
The average particle diameter of the yttria-stabilized zirconia-based oxide particles was determined by particle diameter distribution analysis using a laser scattering particle diameter distribution measuring apparatus ("MT3300EX" manufactured by Nikkiso Co., Ltd.).
（実施例１）
回転式成膜室と加熱炉と前駆体気化部とを備えるＣＶＤ装置（株式会社東栄科学産業製）の回転式成膜室内にイットリア安定化ジルコニア粒子（ＹＳＺ粒子、東ソー株式会社製「ＴＺ−４ＹＳ」、イットリア含有量：４ｍｏｌ％、平均粒子径：１０μｍ）４．００ｇを投入した。アルミナ前駆体としてトリス（ジピバロイルメタナト）アルミニウム（Ａｌ（ＤＰＭ）３、株式会社豊島製作所製）２．００ｇをＣＶＤ装置の前駆体ホルダーに投入した。アルミナ前駆体の加熱温度２１０℃、成膜温度８７５℃、酸素ガス流量１００ｓｃｃｍ、アルゴンガス流量５０ｓｃｃｍ、成膜時の全圧９００Ｐａ、成膜室の回転数２５ｒｐｍの条件で６０分間成膜し、前記ＹＳＺ粒子の表面の少なくとも一部がアルミナ薄膜で被覆されたコアシェル型酸化物材料粉末を得た。
Example 1
Yttria-stabilized zirconia particles (YSZ particles, manufactured by Tosoh Corp. "TZ-4YS" in a rotary film formation chamber of a CVD apparatus (made by Toei Scientific Industry Co., Ltd.) equipped with a rotary film formation chamber, a heating furnace and a precursor vaporization unit Yttria content: 4 mol%, average particle diameter: 10 μm) 4.00 g was added. As an alumina precursor, 2.00 g of tris (dipivaloylmethanato) aluminum (Al (DPM) 3 , manufactured by Toshima Seisakusho Co., Ltd.) was introduced into a precursor holder of a CVD apparatus. The film formation is carried out for 60 minutes under the conditions of heating temperature 210 ° C. for alumina precursor, film formation temperature 875 ° C., oxygen gas flow rate 100 sccm, argon gas flow rate 50 sccm, total pressure 900 Pa during film formation, rotation speed 25 rpm of film formation chamber A core-shell type oxide material powder was obtained in which at least a part of the surface of the YSZ particles was coated with an alumina thin film.
このコアシェル型酸化物材料粉末１００質量部に対するロジウムの担持量が０．０５質量部となるように、前記コアシェル型酸化物材料粉末を硝酸ロジウム水溶液に浸漬して前記コアシェル型酸化物材料粉末の表面に硝酸ロジウムを付着させた後、蒸発乾固させてロジウム担持コアシェル型酸化物材料粉末を得た。その後、このロジウム担持コアシェル型酸化物材料粉末を大気中、５００℃で５時間焼成して触媒粉末を得た。 The surface of the core-shell type oxide material powder is dipped in an aqueous solution of rhodium nitrate so that the amount of rhodium supported per 100 parts by weight of the core-shell type oxide material powder is 0.05 parts by mass. Rhodium nitrate was attached to the reaction mixture and evaporated to dryness to obtain a rhodium-supported core-shell type oxide material powder. Thereafter, the rhodium-supported core-shell type oxide material powder was calcined at 500 ° C. for 5 hours in the air to obtain a catalyst powder.
（実施例２）
アルミナ前駆体の加熱温度を２０５℃に、成膜温度を７５０℃に、酸素ガス流量を２０ｓｃｃｍに、アルゴンガス流量を２０ｓｃｃｍに、成膜時の全圧を５００Ｐａに、成膜時間を１２０分間に変更した以外は実施例１と同様にしてコアシェル型酸化物材料粉末にロジウムが担持された触媒粉末を得た。
(Example 2)
The heating temperature of the alumina precursor is 205 ° C., the film formation temperature is 750 ° C., the oxygen gas flow rate is 20 sccm, the argon gas flow rate is 20 sccm, the total pressure during film formation is 500 Pa, and the film formation time is 120 minutes. In the same manner as in Example 1 except for the change, a core-shell type oxide material powder was obtained to obtain a catalyst powder in which rhodium was supported.
（比較例１）
イットリア安定化ジルコニア粒子（ＹＳＺ粒子）１００質量部に対するアルミナ薄膜の含有量が０．５質量部となるように、ＹＳＺ粒子（東ソー株式会社製「ＴＺ−４ＹＳ」）４．０ｇを、硝酸アルミニウム９水和物（和光純薬工業株式会社製）を水に溶解して調製したアルミナ前駆体水溶液に浸漬して前記ＹＳＺ粒子の表面に硝酸アルミニウムを付着させた後、蒸発乾固させてＹＳＺ粒子の表面の少なくとも一部がアルミナ薄膜で被覆されたコアシェル型酸化物材料粉末を得た。その後、このＹＳＺ粒子の表面の少なくとも一部がアルミナ薄膜で被覆されたコアシェル型酸化物材料粉末を大気中、５００℃で５時間焼成し、さらに、実施例１と同様にして前記コアシェル型酸化物材料粉末にロジウムが担持された触媒粉末を得た。
(Comparative example 1)
4.0 g of YSZ particles ("TZ-4 YS" manufactured by Tosoh Corp.) such that the content of alumina thin film is 0.5 parts by mass with respect to 100 parts by mass of yttria stabilized zirconia particles (YSZ particles), and aluminum nitrate 9 Hydrate (made by Wako Pure Chemical Industries, Ltd.) is dissolved in water and then dipped in an aqueous alumina precursor solution to make aluminum nitrate adhere to the surface of the YSZ particles, and then it is evaporated to dryness to obtain YSZ particles. A core-shell type oxide material powder in which at least a part of the surface was coated with an alumina thin film was obtained. Thereafter, a core-shell type oxide material powder in which at least a part of the surface of this YSZ particle is covered with an alumina thin film is calcined at 500 ° C. for 5 hours in the air, and the core-shell type oxide is further treated in the same manner as in Example 1. A catalyst powder was obtained in which rhodium was supported on the material powder.
（比較例２）
イットリア安定化ジルコニア粒子（ＹＳＺ粒子、東ソー株式会社製「ＴＺ−４ＹＳ」）４．０ｇとアルミナ粒子（ＷＲグレース社製「ＭＩ３０７」）０．０２ｇとを乳鉢で混合した。得られた混合粉末を大気中、５００℃で５時間焼成した。その後、実施例１と同様にして前記混合粉末にロジウムが担持された触媒粉末を得た。
(Comparative example 2)
In a mortar, 4.0 g of yttria-stabilized zirconia particles (YSZ particles, "TZ-4YS" manufactured by Tosoh Corp.) and 0.02 g of alumina particles ("MI 307" manufactured by WR Grace Co., Ltd.) were mixed. The obtained mixed powder was fired at 500 ° C. for 5 hours in the air. Thereafter, in the same manner as in Example 1, a catalyst powder in which rhodium was supported on the mixed powder was obtained.
（比較例３）
イットリア安定化ジルコニア粒子（ＹＳＺ粒子、東ソー株式会社製「ＴＺ−４ＹＳ」）４．０ｇを大気中、５００℃で５時間焼成した。その後、実施例１と同様にして前記ＹＳＺ粒子にロジウムが担持された触媒粉末を得た。
(Comparative example 3)
4.0 g of yttria-stabilized zirconia particles (YSZ particles, "TZ-4YS" manufactured by Tosoh Corp.) was calcined at 500 ° C. for 5 hours in the air. Thereafter, in the same manner as in Example 1, a catalyst powder in which rhodium was supported on the YSZ particles was obtained.
（比較例４）
酸素ガス流量を５０ｓｃｃｍに、アルゴンガス流量を５０ｓｃｃｍに、成膜時間を１５分間に変更した以外は実施例２と同様にしてコアシェル型酸化物材料粉末にロジウムが担持された触媒粉末を得た。
(Comparative example 4)
A catalyst powder having rhodium supported on a core-shell type oxide material powder was obtained in the same manner as in Example 2 except that the oxygen gas flow rate was changed to 50 sccm, the argon gas flow rate was changed to 50 sccm, and the film formation time was changed to 15 minutes.
＜ＴＥＭ観察及びＥＤＸ分析＞
実施例１で得られた触媒粉末について、エネルギー分散型Ｘ線（ＥＤＸ）分光分析装置を備える透過型電子顕微鏡（ＴＥＭ）を用いてＴＥＭ観察及びＥＤＸ分析を行なった。その結果を図３に示す
＜アルミナ系酸化物薄膜の含有量＞
実施例及び比較例で得られた触媒粉末について、誘導結合プラズマ（ＩＣＰ）発光分光分析装置（Ｒｉｇａｋｕ社製「ＣＩＲＩＯＳ １２０ＥＯＰ」）を用いてＩＣＰ分析を行い、Ａｌ元素量からアルミナ系酸化物薄膜の含有量を求めた。
<TEM observation and EDX analysis>
The catalyst powder obtained in Example 1 was subjected to TEM observation and EDX analysis using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray (EDX) spectrometer. The results are shown in FIG. 3 <Content of alumina-based oxide thin film>
The catalyst powders obtained in Examples and Comparative Examples were subjected to ICP analysis using an inductively coupled plasma (ICP) emission spectral analyzer ("CIRIOS 120 EOP" manufactured by Rigaku Corporation), and the amount of Al element was changed to alumina oxide thin film The content was determined.
＜アルミナ系酸化物薄膜の被覆率＞
実施例及び比較例で得られた触媒粉末について、Ｘ線光電子分光分析装置（ＵＬＶＡＣ−ＰＨＩ株式会社製「Ｑｕａｎｔｅｒａ ＳＸＭ」）を用いてＸＰＳ分析を行い、コアシェル型酸化物材料粉末表面のＡｌ濃度からアルミナ系酸化物薄膜の被覆率を求めた。
<Coverage of alumina oxide thin film>
The catalyst powders obtained in Examples and Comparative Examples were subjected to XPS analysis using an X-ray photoelectron spectrometer ("Quantera SXM" manufactured by ULVAC-PHI Ltd.), and the Al concentration in the surface of the core-shell type oxide material powder was determined. The coverage of the alumina-based oxide thin film was determined.
＜アルミナ系酸化物薄膜の平均膜厚＞
実施例及び比較例で得られた触媒粉末について、透過型電子顕微鏡（ＴＥＭ）観察を行ない、得られたＴＥＭ像において、アルミナ系酸化物薄膜の膜厚を４箇所測定し、その平均値を平均膜厚とした。
<Average film thickness of alumina-based oxide thin film>
The catalyst powders obtained in Examples and Comparative Examples were observed with a transmission electron microscope (TEM), and in the obtained TEM images, the film thickness of the alumina-based oxide thin film was measured at four locations, and the average value was averaged It was a film thickness.
＜貴金属粒子の平均粒子径＞
実施例及び比較例で得られた触媒粉末について、全自動触媒ガス吸着量測定装置（株式会社大倉理研製「Ｒ６０１５−Ｓ」）を用いてＣＯのパルス吸着法により貴金属粒子の分散性を測定し、平均粒子径を求めた。
<Average particle size of noble metal particles>
With respect to the catalyst powder obtained in Examples and Comparative Examples, the dispersibility of noble metal particles was measured by the pulse adsorption method of CO using a fully automatic catalyst gas adsorption amount measuring apparatus ("R6015-S" manufactured by Okura Riken Co., Ltd.) The average particle size was determined.
＜水素−昇温還元試験（Ｈ２−ＴＰＲ試験）＞
実施例及び比較例で得られた触媒粉末について水素−昇温還元試験（Ｈ２−ＴＰＲ試験）を行なった。すなわち、触媒粉末０．５ｇを石英反応管に充填し、これを自動昇温脱離分析装置（株式会社大倉理研製「ＴＰ−５０００」）に装着し、酸化処理用混合ガス〔Ｏ２（２０容量％）＋Ａｒ（残部）〕を３０ｍｌ／分で供給しながら前記触媒粉末に６００℃で１５分間の酸化処理を施した。その後、前記触媒粉末を室温まで放冷した後、Ｈ２−ＴＰＲ試験用混合ガス〔Ｈ２（５体積％）＋Ａｒ（残部）〕を３０ｍｌ／分で供給しながら前記触媒粉末を３０℃／分の昇温速度で室温から６００℃まで昇温した。この間の触媒出ガス中のＨ２濃度を質量分析計で測定した。得られたＨ２−ＴＰＲスペクトル（触媒出ガス中のＨ２濃度と触媒粉末の温度との関係を示すグラフ）におけるピーク温度を求めた。その結果を表１に示す。
<Hydrogen - heating reduction test (H 2-TPR Test)>
A hydrogen temperature-programmed reduction test (H 2 -TPR test) was conducted on the catalyst powders obtained in Examples and Comparative Examples. That is, 0.5 g of catalyst powder is packed in a quartz reaction tube, and this is attached to an automatic temperature rising desorption analyzer (“TP-5000” manufactured by Okura Riken Co., Ltd.), and mixed gas [O 2 (20 The catalyst powder was subjected to oxidation treatment at 600 ° C. for 15 minutes while supplying (volume%) + Ar (remaining) at 30 ml / min. Thereafter, the catalyst powder is allowed to cool to room temperature, and then the catalyst powder is heated to 30 ° C./minute while supplying mixed gas of H 2 -TPR [H 2 (5% by volume) + Ar (remainder)] at 30 ml / minute. The temperature was raised from room temperature to 600 ° C. at a temperature rising rate of During this time, the H 2 concentration in the catalyst outgas was measured by a mass spectrometer. The peak temperature in the obtained H 2 -TPR spectrum (a graph showing the relationship between the concentration of H 2 in the catalyst output gas and the temperature of the catalyst powder) was determined. The results are shown in Table 1.
＜ＮＯｘ５０％浄化温度＞
実施例及び比較例で得られた触媒粉末０．５ｇを反応管に充填し、これを低温低濃度触媒性能評価装置（株式会社ベスト測器製「ＣＡＴＡ−５０００ＳＰ」）に装着し、前処理用混合ガス〔ＮＯ（１２００ｐｐｍ）＋ＣＯ２（１０体積％）＋Ｏ２（０．６４６体積％）＋ＣＯ（０．７体積％）＋Ｃ３Ｈ６（１６００ｐｐｍＣ）＋Ｈ２Ｏ（３体積％）＋Ｈ２（０．２３３体積％）＋Ｎ２（残部）〕を１０Ｌ／分で供給しながら前記触媒粉末に６５０℃で１２分間の前処理を施した。その後、前記触媒粉末を３０℃まで放冷した後、モデルガス〔ＮＯ（１２００ｐｐｍ）＋ＣＯ２（１０体積％）＋Ｏ２（０．６４６体積％）＋ＣＯ（０．７体積％）＋Ｃ３Ｈ６（１６００ｐｐｍＣ）＋Ｈ２Ｏ（３体積％）＋Ｈ２（０．２３３体積％）＋Ｎ２（残部）〕を１０Ｌ／分で供給しながら前記触媒粉末を１５℃／分の昇温速度で３０℃から６００℃まで昇温し、各触媒温度において触媒入りガス中及び触媒出ガス中のＮＯ濃度を測定してＮＯｘ浄化率を算出し、ＮＯｘが５０％浄化された時点の触媒温度（ＮＯｘ５０％浄化温度）を求めた。その結果を表１に示す。
<NOx 50% purification temperature>
0.5 g of the catalyst powder obtained in Examples and Comparative Examples is packed in a reaction tube, and this is attached to a low-temperature low-concentration catalyst performance evaluation device ("CATA-5000SP" manufactured by Best Sanki Co., Ltd.) for pretreatment mixed gas [NO (1200ppm) + CO 2 ( 10 vol%) + O 2 (0.646 vol%) + CO (0.7 vol%) + C 3 H 6 ( 1600ppmC) + H 2 O (3 vol%) + H 2 (0 The catalyst powder was pretreated at 650 ° C. for 12 minutes while feeding .233 vol%) + N 2 (remaining) at 10 L / min. Thereafter, the catalyst powder is allowed to cool to 30 ° C., and then the model gas [NO (1200 ppm) + CO 2 (10 volume%) + O 2 (0.646 volume%) + CO (0.7 volume%) + C 3 H 6 (C) The catalyst powder is fed at 30 ° C. to 600 ° C. at a heating rate of 15 ° C./minute while supplying 1600 ppm C) + H 2 O (3 vol%) + H 2 (0.233 vol%) + N 2 (remainder)] at 10 L / min. The temperature is raised to ° C, the NO concentration in the catalyst-containing gas and the catalyst-out gas is measured at each catalyst temperature to calculate the NOx purification rate, and the catalyst temperature at 50% NOx purification (50% NOx purification temperature) I asked for. The results are shown in Table 1.
図３に示したように、Ｚｒ原子及びＹ原子は二次粒子中に均一に存在しており、Ａｌ原子は前記二次粒子の表面に存在していることが確認された。すなわち、実施例１で得られた触媒粉末は、ＹＳＺ粒子の表面の少なくとも一部がアルミナ薄膜で被覆されたものであることが確認された。 As shown in FIG. 3, it was confirmed that the Zr atoms and the Y atoms were uniformly present in the secondary particles, and the Al atoms were present on the surface of the secondary particles. That is, it was confirmed that at least a part of the surface of the YSZ particles was coated with an alumina thin film in the catalyst powder obtained in Example 1.
表１に示した結果から明らかなように、ＹＳＺ粒子を攪拌しながら、Ａｌ（ＤＰＭ）３を用いて化学気相成長法（ＣＶＤ法）により前記ＹＳＺ粒子の表面にアルミナ薄膜を形成した触媒粉末（実施例１〜２）は、ＹＳＺ粒子を硝酸アルミニウム水溶液に浸漬して前記ＹＳＺ粒子の表面にアルミナ薄膜を形成した触媒粉末（比較例１）に比べて、アルミナ薄膜の含有量は少ないが、アルミナ薄膜の膜厚が薄く、被覆率が大きいものであることがわかった。このようなアルミナ薄膜の膜厚が薄く、被覆率が大きい触媒粉末（実施例１〜２）は、アルミナ薄膜の膜厚が厚く、被覆率が小さい触媒粉末（比較例１）に比べて、Ｈ２−ＴＰＲスペクトルにおけるピーク温度が低く、酸化されたロジウムが還元されやすいものであり、また、ＮＯｘ５０％浄化温度が低く、ＮＯｘ浄化性能に優れたものであることがわかった。 As is clear from the results shown in Table 1, catalyst powder in which an alumina thin film was formed on the surface of the YSZ particles by chemical vapor deposition (CVD) using Al (DPM) 3 while stirring the YSZ particles. In Examples 1 and 2, the content of the alumina thin film is smaller than that of the catalyst powder (Comparative Example 1) in which the alumina thin film is formed on the surface of the YSZ particles by immersing the YSZ particles in an aqueous solution of aluminum nitrate. It was found that the film thickness of the alumina thin film was thin and the coverage was large. The catalyst powder (Examples 1 and 2) with a thin film thickness of such an alumina thin film and a large coverage is H compared to the catalyst powder with a large film thickness of an alumina thin film and a small coverage (Comparative Example 1). It was found that the peak temperature in the 2- TPR spectrum is low, oxidized rhodium is easily reduced, and the NOx 50% purification temperature is low and the NOx purification performance is excellent.
また、ＹＳＺ粒子とアルミナ粒子とを物理混合した触媒粉末（比較例２）は、本発明の触媒粉末（実施例１〜２）に比べて、Ｈ２−ＴＰＲスペクトルにおけるピーク温度が高く、酸化されたロジウムが還元されにくいものであり、また、ＮＯｘ５０％浄化温度が高く、ＮＯｘ浄化性能に劣るものであることがわかった。 Further, the catalyst powder (comparative example 2) in which the YSZ particles and the alumina particles are physically mixed has a higher peak temperature in the H 2 -TPR spectrum and is oxidized as compared with the catalyst powder of the present invention (Examples 1 and 2) It was found that rhodium is difficult to be reduced, and that the NOx 50% purification temperature is high and the NOx purification performance is inferior.
さらに、ＹＳＺ粒子にロジウムを担持した触媒粉末（比較例３）は、Ｈ２−ＴＰＲスペクトルにおけるピーク温度が本発明の触媒粉末（実施例１）と同等であり、酸化されたロジウムが還元されやすいものであったが、ＮＯｘ５０％浄化温度が本発明の触媒粉末（実施例１〜２）に比べて高く、ＮＯｘ浄化性能に劣るものであることがわかった。 Furthermore, in the catalyst powder in which rhodium is supported on YSZ particles (Comparative Example 3), the peak temperature in the H 2 -TPR spectrum is equivalent to the catalyst powder of the present invention (Example 1), and oxidized rhodium is easily reduced. However, it was found that the NOx 50% purification temperature is higher than the catalyst powder of the present invention (Examples 1 and 2), and the NOx purification performance is inferior.
また、ＹＳＺ粒子を攪拌しながら、Ａｌ（ＤＰＭ）３を用いて化学気相成長法（ＣＶＤ法）により前記ＹＳＺ粒子の表面にアルミナ薄膜を形成した触媒粉末であっても、アルミナ薄膜の含有量が少なく、被覆率が小さい場合（比較例４）には、本発明の触媒粉末（実施例１〜２）に比べて、Ｈ２−ＴＰＲスペクトルにおけるピーク温度が高く、酸化されたロジウムが還元されにくいものであり、また、ＮＯｘ５０％浄化温度が高く、ＮＯｘ浄化性能に劣るものであることがわかった。 Moreover, even if it is a catalyst powder in which an alumina thin film is formed on the surface of the YSZ particles by chemical vapor deposition (CVD method) using Al (DPM) 3 while stirring the YSZ particles, the content of the alumina thin film When the coverage is small (Comparative Example 4), the peak temperature in the H 2 -TPR spectrum is higher than that of the catalyst powder of the present invention (Examples 1 and 2), and oxidized rhodium is reduced. It was found that it was difficult, and that the NOx 50% purification temperature was high, and the NOx purification performance was inferior.
以上説明したように、本発明のコアシェル型酸化物材料を用いることによって、酸化された貴金属が還元されやすく、ＮＯｘ浄化性能を有する排ガス浄化用触媒を得ることが可能となる。 As described above, by using the core-shell type oxide material of the present invention, the oxidized noble metal is easily reduced, and it becomes possible to obtain an exhaust gas purification catalyst having NOx purification performance.
したがって、本発明のコアシェル型酸化物材料は、自動車の内燃機関等から排出される、窒素酸化物を含有するガスを浄化するための排ガス浄化用触媒の担体や助触媒等として有用である。 Therefore, the core-shell type oxide material of the present invention is useful as a support, a promoter, etc. of an exhaust gas purification catalyst for purifying a gas containing nitrogen oxide, which is discharged from an internal combustion engine or the like of a car.
１：アルミナ系酸化物薄膜
２：貴金属粒子
３：ジルコニア系酸化物粒子
1: Alumina-based oxide thin film 2: Noble metal particles 3: Zirconia-based oxide particles
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03232724A (en) * | 1990-02-09 | 1991-10-16 | Nippon Shokubai Kagaku Kogyo Co Ltd | Zirconia spherical particle and production thereof |
| JP2001113171A (en) * | 1999-10-15 | 2001-04-24 | Toyota Motor Corp | Method of manufacturing catalyst for cleaning exhaust gas |
| JP2012516235A (en) * | 2009-01-29 | 2012-07-19 | ビー・エイ・エス・エフ、コーポレーション | Mechanically fused materials for pollution reduction in mobile and stationary sources |
| JP2015071520A (en) * | 2013-10-04 | 2015-04-16 | 株式会社豊田中央研究所 | Ceria-zirconia-based complex oxide, production method thereof and catalyst for exhaust gas purification using the ceria-zirconia-based complex oxide |
| JP2016168586A (en) * | 2015-03-12 | 2016-09-23 | 株式会社豊田中央研究所 | Core shell carrier and production method therefor, exhaust emission control catalyst using the core shell carrier and production method therefor, and exhaust emission control method using the exhaust emission control catalyst |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03232724A (en) * | 1990-02-09 | 1991-10-16 | Nippon Shokubai Kagaku Kogyo Co Ltd | Zirconia spherical particle and production thereof |
| JP2001113171A (en) * | 1999-10-15 | 2001-04-24 | Toyota Motor Corp | Method of manufacturing catalyst for cleaning exhaust gas |
| JP2012516235A (en) * | 2009-01-29 | 2012-07-19 | ビー・エイ・エス・エフ、コーポレーション | Mechanically fused materials for pollution reduction in mobile and stationary sources |
| JP2015071520A (en) * | 2013-10-04 | 2015-04-16 | 株式会社豊田中央研究所 | Ceria-zirconia-based complex oxide, production method thereof and catalyst for exhaust gas purification using the ceria-zirconia-based complex oxide |
| JP2016168586A (en) * | 2015-03-12 | 2016-09-23 | 株式会社豊田中央研究所 | Core shell carrier and production method therefor, exhaust emission control catalyst using the core shell carrier and production method therefor, and exhaust emission control method using the exhaust emission control catalyst |
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