JP3427422B2 - Exhaust gas purification catalyst and method for producing the same - Google Patents
Exhaust gas purification catalyst and method for producing the sameInfo
- Publication number
- JP3427422B2 JP3427422B2 JP16789893A JP16789893A JP3427422B2 JP 3427422 B2 JP3427422 B2 JP 3427422B2 JP 16789893 A JP16789893 A JP 16789893A JP 16789893 A JP16789893 A JP 16789893A JP 3427422 B2 JP3427422 B2 JP 3427422B2
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- exhaust gas
- metal
- layer
- catalyst layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000003054 catalyst Substances 0.000 title claims description 182
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 238000000746 purification Methods 0.000 title description 39
- 239000010410 layer Substances 0.000 claims description 119
- 239000007789 gas Substances 0.000 claims description 54
- 229910000510 noble metal Inorganic materials 0.000 claims description 35
- 229910044991 metal oxide Inorganic materials 0.000 claims description 34
- 150000004706 metal oxides Chemical class 0.000 claims description 34
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 24
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 22
- 239000000203 mixture Substances 0.000 claims description 10
- 230000001590 oxidative effect Effects 0.000 claims description 9
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 8
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 4
- 238000005470 impregnation Methods 0.000 claims description 4
- 239000011247 coating layer Substances 0.000 claims description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims 1
- 229910052717 sulfur Inorganic materials 0.000 claims 1
- 239000011593 sulfur Substances 0.000 claims 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 108
- 239000000463 material Substances 0.000 description 31
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 24
- 239000010948 rhodium Substances 0.000 description 17
- 238000000034 method Methods 0.000 description 15
- 239000010970 precious metal Substances 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 238000007254 oxidation reaction Methods 0.000 description 8
- 229910052697 platinum Inorganic materials 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 7
- 238000002485 combustion reaction Methods 0.000 description 6
- 229910052703 rhodium Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 229910052741 iridium Inorganic materials 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 229910021536 Zeolite Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 230000032683 aging Effects 0.000 description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000010457 zeolite Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910052878 cordierite Inorganic materials 0.000 description 2
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical group [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 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 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- DANYXEHCMQHDNX-UHFFFAOYSA-K trichloroiridium Chemical compound Cl[Ir](Cl)Cl DANYXEHCMQHDNX-UHFFFAOYSA-K 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- -1 zeolite Chemical compound 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Description
【０００１】[0001]
【産業上の利用分野】本発明は排気ガス浄化用触媒及び
その製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying catalyst and a method for producing the same.
【０００２】[0002]
【従来の技術】自動車エンジンの排気ガス中に含まれる
ＮＯｘ（窒素酸化物）を理論空燃比よりも酸素が過剰な
雰囲気で分解除去するに適した排気ガス浄化用触媒とし
て、ゼオライトに各種の活性種を担持させたものは一般
に知られている。例えば、特開平４−２４３５４５号公
報には、ゼオライトに活性種としてＰｔ及びＲｈをイオ
ン交換法や含浸法によって担持させることが記載されて
いる。2. Description of the Related Art Zeolite has various activities as an exhaust gas purifying catalyst suitable for decomposing and removing NOx (nitrogen oxide) contained in exhaust gas of an automobile engine in an atmosphere in which oxygen exceeds the stoichiometric air-fuel ratio. A seed-supported material is generally known. For example, Japanese Unexamined Patent Publication No. 4-243545 describes that Pt and Rh as active species are supported on zeolite by an ion exchange method or an impregnation method.
【０００３】このような触媒は、上記排気ガス中のＨＣ
を燃焼させるとともに、その過程で生ずるＨＣ燃焼中間
生成物（不完全燃焼生成物）とＮＯｘとの反応によって
該ＮＯｘを還元分解させると考えられる。Such a catalyst is used for the HC in the exhaust gas.
It is considered that the NOx is reduced and decomposed by the reaction between the HC combustion intermediate product (incomplete combustion product) generated in the process and NOx.
【０００４】[0004]
【発明が解決しようとする課題】しかし、ゼオライトの
ような金属含有シリケートにＰｔ等の貴金属を担持させ
た触媒の場合、排気ガス温度が高くなるとＮＯｘ浄化率
が低くなる。これは、高温では触媒活性点において次の
酸化反応が独立して起こり（ＨＣがＮＯｘと反応するこ
となく完全に酸化され）、該ＨＣによるＮＯｘの選択的
な還元が起こり難くなるためと考えられる。However, in the case of a catalyst in which a noble metal such as Pt is supported on a metal-containing silicate such as zeolite, the NOx purification rate decreases as the exhaust gas temperature increases. This is presumably because at the high temperature, the next oxidation reaction occurs independently at the catalytically active site (HC is completely oxidized without reacting with NOx), and selective reduction of NOx by the HC becomes difficult to occur. .
【０００５】ＮＯ＋1/2 Ｏ2 →ＮＯ2 Ｃn Ｈm ＋(n+m/4) Ｏ2 →n ＣＯ2 ＋m/2 Ｈ2ＯNO + 1/2 O 2 → NO 2 Cn Hm + (n + m / 4) O 2 → n CO 2 + m / 2 H 2 O
【０００６】[0006]
【課題を解決するための手段及びその作用】本発明は、
このような課題に対して、ＨＣの酸化を抑制してＨＣ燃
焼中間生成物を得ることができるようにして、ＨＣがＮ
Ｏｘの分解に有効に寄与するようにするものである。Means for Solving the Problem and Its Action The present invention is
In order to solve such a problem, it is possible to suppress the oxidation of HC and obtain an HC combustion intermediate product, so that HC
It is intended to effectively contribute to the decomposition of Ox.
【０００７】すなわち、上記課題を解決する第１の手段
（請求項１記載の発明）は、触媒担体の上に上下２層の
触媒層を備えていて、排気ガス中のＮＯｘをＨＣの存在
下で分解する排気ガス浄化用触媒であって、上記上層が
下層に比べてＨＣ酸化能が低い触媒によって形成されて
おり、上記上層が活性種として貴金属を有し、且つ金属
酸化物が混合されてなる触媒によって形成され、上記下
層が金属含有シリケートに貴金属を活性種として担持さ
せた触媒によって形成されていることを特徴とする排気
ガス浄化用触媒である。That is, the first means for solving the above-mentioned problems (the invention according to claim 1) is that the upper and lower two catalyst layers are provided on the catalyst carrier, and NOx in the exhaust gas is present in the presence of HC. in a decomposing exhaust gas purifying catalyst, HC oxidizing ability the upper layer than the lower layer is formed by low catalyst
The upper layer has a noble metal as an active species, and
It is formed by a catalyst that is a mixture of oxides,
The layer supports the precious metal as the active species on the metal-containing silicate.
The exhaust gas purifying catalyst is characterized in that it is formed of an impregnated catalyst.
【０００８】当手段の場合、下層を従来の金属含有シリ
ケートに貴金属を担持させた酸化能が高い触媒として
も、上層の酸化能が低いから高温の排気ガス中のＨＣが
当該触媒との接触によって直ちに完全酸化されることを
抑えることができる。よって、この上層によって得られ
たＨＣ燃焼中間生成物を利用してＮＯｘを還元分解する
ことが可能になる。また、下層の触媒のＨＣ酸化能が高
いから、排気ガス温度が低い場合のＮＯｘの分解にも支
障はない。In the case of this means, even if the lower layer is a conventional catalyst having a high oxidizing ability in which a noble metal is supported on a metal-containing silicate, since the oxidizing ability of the upper layer is low, HC in the hot exhaust gas may come into contact with the catalyst. Immediate complete oxidation can be suppressed. Therefore, NOx can be reduced and decomposed by using the HC combustion intermediate product obtained by the upper layer. Further, since the lower layer catalyst has a high HC oxidizing ability, there is no problem in decomposing NOx when the exhaust gas temperature is low.
【０００９】また、上層及び下層に活性種としてＨＣ酸
化能が比較的高い貴金属を用いているが、上層は金属酸
化物が混合されてなるから、該金属酸化物によって貴金
属の反応性が低下し、上記ＨＣ酸化能が低くなる。 HC acid is used as an active species in the upper and lower layers.
A noble metal with a relatively high chemical potential is used, but the upper layer is metallic acid.
Compound is mixed, the precious metal is
The reactivity of the genus is lowered, and the HC oxidizing ability is lowered.
【００１０】ここに、上記金属含有シリケートとは、結
晶の骨格の一部を金属原子が構成していて、ミクロの細
孔を有する結晶質多孔のシリケートを意味し、ゼオライ
トがその代表的な例である。金属としてＡｌに代えて、
あるいはＡｌと共に、Ｂ、Ｇａ、Ｍｎ、Ｆｅ、Ｎｉ、Ｃ
ｏ、Ｖ、Ｗ、Ｓｎ、Ｐｂ、Ｚｎ、Ｐｔ、Ｐｄ、Ｒｈ、Ｉ
ｒ、Ｃｅ、Ｔｂ等を用いてなる金属含有シリケートであ
ってもよい。 Here, the metal-containing silicate means a crystalline porous silicate in which a metal atom constitutes a part of the skeleton of the crystal and has micropores, and a typical example thereof is zeolite. Is. Instead of Al as a metal,
Or with Al, B, Ga, Mn, Fe, Ni, C
o, V, W, Sn, Pb, Zn, Pt, Pd, Rh, I
It may be a metal-containing silicate made of r, Ce, Tb or the like .
【００１１】上記課題を解決する第２の手段（請求項２
に記載の発明）は、上記第１の手段において、上記上層
が金属酸化物とＨ型金属含有シリケートとの混合物に上
記貴金属を担持させてなる触媒によって形成されている
点に特徴がある。A second means for solving the above problems ( claim 2)
The invention described in 1 ) above is characterized in that, in the first means, the upper layer is formed by a catalyst in which the noble metal is supported on a mixture of a metal oxide and an H-type metal-containing silicate.
【００１２】当手段の場合、上層のＨ型金属含有シリケ
ートが排気ガス中のＨＣを捕らえるトラップとして機能
し、ＮＯｘの浄化に有利になる。Ｈ型金属含有シリケー
トとしてはＨ型ＺＳＭ−５が好適であり、その場合の該
Ｈ型ＺＳＭ−５の最適な混合量は金属酸化物の種類によ
って異なるが、Ｈ型ＺＳＭ−５及び金属酸化物の総量の
７０wt％以下とすることが好適である。それよりも多い
場合は、相対的に金属酸化物の量が不足し、所期の効果
を得ることができないからである。In the case of this means, the upper layer H-type metal-containing silicate functions as a trap for trapping HC in the exhaust gas, which is advantageous for purifying NOx. H-type ZSM-5 is suitable as the H-type metal-containing silicate, and the optimum mixing amount of the H-type ZSM-5 in that case varies depending on the kind of the metal oxide. It is preferable that the amount is 70 wt% or less of the total amount. When the amount is larger than that, the amount of the metal oxide is relatively insufficient, and the desired effect cannot be obtained.
【００１３】上記課題を解決する第３の手段（請求項３
に記載の発明）は、上記第１及び第２の各手段におい
て、上記上層の触媒が活性種としてＰｔを含み、金属酸
化物としてＣｅＯ 2 又はＡｌ 2 Ｏ 3 又はＴｉＯ 2 を含む点に
特徴がある。A third means for solving the above problems ( claim 3)
Invention) described, in the first and second respective means, the upper layer of the catalyst comprises Pt as an active species, metal acid
It is characterized in that CeO 2 or Al 2 O 3 or TiO 2 is contained as a compound .
【００１４】当手段の場合、活性種としてのＰｔはＨＣ
の酸化に有効であり、また、当該列挙の各金属酸化物は
いずれもＰｔによるＨＣの酸化力の抑制に効果がある。In the case of this means, Pt as the active species is HC
And the metal oxides listed above are effective in suppressing the oxidizing power of HC by Pt.
【００１５】上記課題を解決する第４の手段（請求項４
に記載の発明）は、上記第１及び第２の各手段におい
て、上記下層の触媒が金属酸化物としてＡｌ 2 Ｏ 3 を含む
点に特徴がある。 A fourth means for solving the above problems (claim 4)
In the above first and second means, the lower layer catalyst contains Al 2 O 3 as a metal oxide.
The point is characteristic.
【００１６】上記課題を解決する第５の手段（請求項５
に記載の発明）は、上記第２の手段に係る排気ガス浄化
用触媒の製造方法であって、金属含有シリケートに貴金
属を担持させてなる触媒を触媒担体の表面にコーティン
グすることによって下層を形成した後、該下層の上に金
属酸化物とＨ型金属含有シリケートとの混合物をコーテ
ィングし、該コーティング層に貴金属を含浸によって担
持させることを特徴とする。Fifth means for solving the above problems (claim 5)
The invention according to claim 2) is a method for producing an exhaust gas purifying catalyst according to the second means, wherein a lower layer is formed by coating the surface of a catalyst carrier with a catalyst in which a noble metal is supported on a metal-containing silicate. After that, a mixture of a metal oxide and an H-type metal-containing silicate is coated on the lower layer, and the noble metal is supported on the coating layer by impregnation.
【００１７】当手段の場合、上層においては、金属含有
シリケートと金属酸化物との混合物をコーティングした
後に貴金属の含浸担持を行なうから、該貴金属が金属酸
化物に接触配置され易くなり、金属酸化物を貴金属によ
るＨＣ酸化の抑制に寄与させる上で有利になる。In the case of this means, since the noble metal is impregnated and supported in the upper layer after coating the mixture of the metal-containing silicate and the metal oxide, the noble metal is easily placed in contact with the metal oxide, and the metal oxide is Is advantageous in contributing to the suppression of HC oxidation by the noble metal.
【００１８】[0018]
【発明の効果】上記第１の手段によれば、触媒担体上に
上下２層の触媒層のうち上層が下層に比べてＨＣ酸化能
が低い触媒によって形成されているから、下層に酸化能
が高い触媒を採用して排気ガス温度が低い場合のＮＯｘ
浄化率の向上を図りながら、排気ガス温度が高いときに
は上層によるＨＣの酸化の抑制によってＮＯｘの浄化を
確保することができ、しかも、上層が活性種として貴金
属を有し且つ金属酸化物が混合されてなる触媒によって
形成され、下層が金属含有シリケートに貴金属を活性種
として担持させた触媒によって形成されているから、排
気ガス温度が低いときに所期のＮＯｘ浄化率を確保しな
がら、排気ガス温度が高いときのＨＣの酸化抑制に有利
になる。According to the first means, the upper layer of the upper and lower two catalyst layers is formed of a catalyst having a lower HC oxidizing ability than the lower layer, so that the lower layer has an oxidizing ability. NOx when high exhaust gas temperature is adopted by using high catalyst
While improving the purification rate, when the exhaust gas temperature is high, purification of NOx can be ensured by suppressing the oxidation of HC by the upper layer , and moreover, the upper layer has a noble metal as an active species and is mixed with a metal oxide. Since the lower layer is formed by a catalyst in which a noble metal is supported as an active species on a metal-containing silicate, the lower NOx purification rate is ensured while the exhaust gas temperature is low when the exhaust gas temperature is low. When it is high, it becomes advantageous for suppressing the oxidation of HC.
【００１９】上記第２の手段によれば、上層が金属酸化
物とＨ型金属含有シリケートとの混合物に上記貴金属を
担持させてなる触媒によって形成されているから、当該
上層のＨ型金属含有シリケートによって排気ガス中のＨ
Ｃを捕らえて不完全燃焼させＮＯｘの浄化率を高める上
で有利になる。According to the second means, since the upper layer is formed by the catalyst in which the above noble metal is supported on the mixture of the metal oxide and the H-type metal-containing silicate, the H-type metal-containing silicate of the upper layer is formed. Due to H in the exhaust gas
This is advantageous in capturing C and causing incomplete combustion to increase the purification rate of NOx.
【００２０】上記第３の手段によれば、上層の触媒が活
性種としてＰｔを含み、金属酸化物としてＣｅＯ 2 又は
Ａｌ 2 Ｏ 3 又はＴｉＯ 2 を含むから、上記第１及び第２の
各手段を実施する有力な手段となる。According to the third means, the catalyst in the upper layer contains Pt as an active species, and CeO 2 or metal oxide is used as the metal oxide.
Since it contains Al 2 O 3 or TiO 2, it is an effective means for carrying out the first and second means.
【００２１】上記第４の手段によれば、下層の触媒が金
属酸化物としてＡｌ 2 Ｏ 3 を含むから、上記第１及び第２
の各手段を実施する有力な手段となる。 According to the fourth means, the lower catalyst is gold.
Since Al 2 O 3 is contained as a group oxide , the first and second
It becomes a powerful means to implement each means of.
【００２２】上記第５の手段によれば、金属含有シリケ
ートに貴金属を担持させてなる触媒を触媒担体の表面に
コーティングすることによって下層を形成した後、該下
層の上に金属酸化物とＨ型金属含有シリケートとの混合
物をコーティングし、該コーティング層に貴金属を含浸
によって担持させるようにしたから、貴金属を金属酸化
物に接触配置して該貴金属によるＨＣ酸化を抑制する上
で有利になる。According to the fifth means, the lower layer is formed by coating the surface of the catalyst carrier with a catalyst in which a noble metal is supported on a metal-containing silicate, and then a metal oxide and H type are formed on the lower layer. Since the mixture with the metal-containing silicate is coated and the noble metal is supported on the coating layer by impregnation, it is advantageous to place the noble metal in contact with the metal oxide and suppress HC oxidation by the noble metal.
【００２３】[0023]
【実施例】以下、本発明の実施例を図面に基づいて説明
する。Embodiments of the present invention will be described below with reference to the drawings.
【００２４】＜触媒構造＞
図１に示す排気ガス浄化用触媒において、１は触媒担
体、２は下触媒層、３は上触媒層である。触媒担体１は
コーディエライト製のハニカム担体によって構成されて
いる。下触媒層２は、金属含有シリケートとしてのＨ型
ＺＳＭ−５（ケイバン比＝７０）を母材とし該母材に活
性種としてＰｔ、Ｉｒ及びＲｈを担持させてなる触媒に
よって構成されている。上触媒層３は、Ｈ型ＺＳＭ−５
と金属酸化物粉との混合物を母材とし該母材にＰｔ、Ｉ
ｒ及びＲｈを担持させてなる触媒によって構成されてい
る。<Catalyst Structure> In the exhaust gas purifying catalyst shown in FIG. 1, 1 is a catalyst carrier, 2 is a lower catalyst layer, and 3 is an upper catalyst layer. The catalyst carrier 1 is composed of a cordierite honeycomb carrier. The lower catalyst layer 2 is composed of a catalyst in which H-type ZSM-5 (Cayvan ratio = 70) as a metal-containing silicate is used as a base material and Pt, Ir and Rh as active species are supported on the base material. The upper catalyst layer 3 is an H-type ZSM-5
And a metal oxide powder as a base material.
It is composed of a catalyst supporting r and Rh.
【００２５】＜実施例１〜１１，比較例１，２について
＞
（実施例１）
上記排気ガス浄化用触媒は以下の方法によって製造し
た。<Examples 1 to 11 and Comparative Examples 1 and 2> (Example 1) The above exhaust gas purifying catalyst was produced by the following method.
【００２６】−下触媒層の形成−
２価ジアミン白金、硝酸ロジウム及び塩化イリジウムを
前二者についてはイオン交換水に、後者についてはエタ
ノールにそれぞれ溶解し、Ｈ型ＺＳＭ−５（ケイバン比
＝７０）とを混合し、均一に混練した後、乾燥させた。
このとき、Ｐｔ、Ｉｒ及びＲｈは各々３．３wt％、１．
１wt％、０．０５wt％となるようにした。得られた触媒
パウダをアルミナバインダ及び水と混合してスラリーを
形成し、コーディエライト製ハニカム担体（４００セル
／inch2 ）にウォッシュコートした。ウォッシュコート
量はハニカム担体に対して１５重量％（バインダ量も含
む）である。-Formation of lower catalyst layer- Divalent diamine platinum, rhodium nitrate and iridium chloride are dissolved in ion-exchanged water for the former two and ethanol for the latter respectively, and H type ZSM-5 (Cayvan ratio = 70) is dissolved. ) Was mixed and kneaded uniformly, and then dried.
At this time, Pt, Ir, and Rh are 3.3 wt% and 1.
It was made to be 1 wt% and 0.05 wt%. The obtained catalyst powder was mixed with an alumina binder and water to form a slurry, which was wash-coated on a honeycomb carrier made of cordierite (400 cells / inch 2 ). The washcoat amount is 15% by weight (including the binder amount) with respect to the honeycomb carrier.
【００２７】当該コート後には焼成を行なわなくとも乾
燥（２００℃×３時間）だけでもよいが、本実施例では
乾燥後に４００℃で焼成を行なった。After the coating, baking (200 ° C. × 3 hours) may be performed without baking, but in this embodiment, baking is performed at 400 ° C. after drying.
【００２８】−上触媒層の形成−
Ｐｔ、Ｉｒ及びＲｈの各々を２wt％、０．３wt％、０．
０２wt％にするとともに、Ｈ型ＺＳＭ−５のケイバン比
を３０とする他は上記下触媒層の場合と同様にして触媒
パウダを調製し、該パウダと金属酸化物としてのＣｅＯ
2 とを後者が４０wt％となる量比で混合し、下触媒層の
場合と同様の方法で該下触媒層の上にウォッシュコート
し、同様の乾燥及び焼成を行なった。-Formation of Upper Catalyst Layer- Pt, Ir and Rh are added in an amount of 2 wt%, 0.3 wt%, 0.
A catalyst powder was prepared in the same manner as in the case of the above lower catalyst layer except that the H-type ZSM-5 had a Cavern ratio of 30, and the powder and CeO 2 as a metal oxide were used.
2 and 40 were mixed in an amount ratio such that the latter was 40% by weight, wash-coated on the lower catalyst layer in the same manner as in the lower catalyst layer, and dried and calcined in the same manner.
【００２９】（実施例２〜１１）
実施例２として、上触媒層の母材にＮａ型ＺＳＭ−５
（ケイバン比３０）を用いる他は実施例１と同じ条件で
排気ガス浄化用触媒を製造した。(Examples 2 to 11) As Example 2, as the base material of the upper catalyst layer, Na-type ZSM-5 was used.
An exhaust gas purification catalyst was produced under the same conditions as in Example 1 except that (Cayvan ratio 30) was used.
【００３０】実施例３として、上触媒層の母材にＨ型Ｚ
ＳＭ−５（ケイバン比２００）を用いる他は実施例１と
同じ条件で排気ガス浄化用触媒を製造した。As Example 3, as a base material of the upper catalyst layer, H-type Z
An exhaust gas purification catalyst was produced under the same conditions as in Example 1 except that SM-5 (Cayvan ratio 200) was used.
【００３１】実施例４として、上触媒層の母材にＨ型Ｚ
ＳＭ−５（ケイバン比７０）を用い、下触媒層にＡｌ2
Ｏ3を２０wt％となる量比で混入した他は実施例１と同
じ条件で排気ガス浄化用触媒を製造した。As Example 4, as a base material of the upper catalyst layer, H-type Z
Using SM-5 (Cayban ratio 70), Al 2 is used as the lower catalyst layer.
An exhaust gas purifying catalyst was manufactured under the same conditions as in Example 1 except that O 3 was mixed in an amount ratio of 20 wt%.
【００３２】実施例５では、下触媒層の母材にＨ型ＺＳ
Ｍ−５（ケイバン比７０）を用いる一方、上触媒層につ
いては、ＣｅＯ2とＨ型ＺＳＭ−５とを混合してから、
これらに活性種を蒸発乾固法よって担持させるようにし
た。他は実施例１と同じ条件で排気ガス浄化用触媒を製
造した。In Example 5, H-type ZS was used as the base material of the lower catalyst layer.
While using M-5 (Cayvan ratio 70), for the upper catalyst layer, after mixing CeO 2 and H-type ZSM-5,
The active species were carried on these by evaporation to dryness. An exhaust gas purifying catalyst was manufactured under the same conditions as in Example 1 except for the above.
【００３３】実施例６として、上触媒層の母材にＨ型Ｚ
ＳＭ−５（ケイバン比７０）を用いる一方、下触媒層の
活性種としてＰｔ及びＩｒを用い各々を３．３wt％、
１．１wt％とする他は実施例１と同じ条件で排気ガス浄
化用触媒を製造した。As Example 6, H type Z was used as the base material of the upper catalyst layer.
While using SM-5 (Cayvan ratio 70), Pt and Ir were used as active species of the lower catalyst layer, and 3.3 wt% of each was used.
An exhaust gas purification catalyst was produced under the same conditions as in Example 1 except that the amount was 1.1 wt%.
【００３４】実施例７として、上触媒層の母材にＨ型Ｚ
ＳＭ−５（ケイバン比７０）を用いる一方、下触媒層の
母材にＮａ型ＺＳＭ−５（ケイバン比３０）を用いる他
は実施例１と同じ条件で排気ガス浄化用触媒を製造し
た。As Example 7, as a base material of the upper catalyst layer, H-type Z
An exhaust gas purifying catalyst was produced under the same conditions as in Example 1 except that SM-5 (Cayban ratio 70) was used while Na-type ZSM-5 (Cayvan ratio 30) was used as the base material of the lower catalyst layer.
【００３５】実施例８では、上触媒層の母材にＨ型ＺＳ
Ｍ−５（ケイバン比７０）を用いるとともに、該母材と
ＣｅＯ2との混合物を下触媒層の上にウォッシュコート
した後、Ｐｔ、Ｉｒ及びＲｈの溶液に当該ハニカム触媒
を所定時間浸漬して引上げ、大気中で乾燥させた後に焼
成を行なうことにより、当該上触媒層を形成した。他は
実施例１と同じ条件で排気ガス浄化用触媒を製造した。In Example 8, H-type ZS was used as the base material of the upper catalyst layer.
M-5 (Cayban ratio 70) was used, and after a mixture of the base material and CeO 2 was wash-coated on the lower catalyst layer, the honeycomb catalyst was immersed in a solution of Pt, Ir, and Rh for a predetermined time. The upper catalyst layer was formed by pulling up, drying in air, and then firing. An exhaust gas purifying catalyst was manufactured under the same conditions as in Example 1 except for the above.
【００３６】実施例９として、上触媒層の母材にＨ型Ｚ
ＳＭ−５（ケイバン比７０）を用いるとともに、金属酸
化物としてＡｌ2Ｏ3を用いる他は実施例１と同じ条件で
排気ガス浄化用触媒を製造した。As Example 9, as a base material of the upper catalyst layer, H-type Z
An exhaust gas purification catalyst was produced under the same conditions as in Example 1 except that SM-5 (Cayvan ratio 70) was used and Al 2 O 3 was used as the metal oxide.
【００３７】実施例１０として、実施例９と同じ条件で
製造した排気ガス浄化用触媒にエージング（８００℃×
８時間の熱処理）を行なったものを得た。As Example 10, an exhaust gas purifying catalyst produced under the same conditions as in Example 9 was aged (800 ° C x
A heat-treated product for 8 hours was obtained.
【００３８】実施例１１として、実施例８と同じ条件で
製造した排気ガス浄化用触媒にエージング（８００℃×
８時間の熱処理）を行なったものを得た。As Example 11, the exhaust gas purifying catalyst produced under the same conditions as in Example 8 was aged (800 ° C x
A heat-treated product for 8 hours was obtained.
【００３９】（比較例１，２）
比較例１として、実施例１における下触媒層と同じ触媒
層１層のみ（但しウォッシュコート量３５wt％）とした
排気ガス浄化用触媒を製造した。(Comparative Examples 1 and 2) As Comparative Example 1, an exhaust gas purifying catalyst was produced in which only one catalyst layer, which was the same as the lower catalyst layer in Example 1, was used (however, the washcoat amount was 35 wt%).
【００４０】比較例２として、上記比較例１と同じ条件
で製造した排気ガス浄化用触媒にエージング（８００℃
×８時間の熱処理）を行なったものを得た。As Comparative Example 2, an exhaust gas purifying catalyst produced under the same conditions as in Comparative Example 1 was aged (800 ° C.).
X 8 hours of heat treatment) was obtained.
【００４１】（触媒の評価）
上記各例の触媒につき、これらにＡ／Ｆ＝２２相当の模
擬排気ガスをＳＶ＝５５０００ｈ-1で流して、ＮＯｘ浄
化率を測定した。(Evaluation of Catalyst) With respect to the catalyst of each of the above examples, a simulated exhaust gas corresponding to A / F = 22 was caused to flow at SV = 55000 h −1 to measure the NOx purification rate.
【００４２】表１は排気ガス温度３００℃でのＮＯｘ浄
化率の測定結果を示す。なお、表１において、記号Ｈ−
ＺはＨ型ＺＳＭ−５、Ｎａ−ＺはＮａ型ＺＳＭ−５、当
該記号に続く括弧書きの数値はケイバン比を表わす。ま
た、Ｗ／Ｃ量とはウォッシュコート量のことである。さ
らに、実施例５の下触媒層のＣｅＯ2＊は先に述べた通
り製法が異なることを意味する。Table 1 shows the measurement results of the NOx purification rate at the exhaust gas temperature of 300 ° C. In Table 1, the symbol H-
Z is H type ZSM-5, Na-Z is Na type ZSM-5, and the numerical value in parentheses following the symbol represents the Cavan ratio. The W / C amount is the washcoat amount. Further, CeO 2 * in the lower catalyst layer of Example 5 means that the manufacturing method is different as described above.
【００４３】[0043]
【表１】 [Table 1]
【００４４】表１によれば、実施例１〜９はいずれも比
較例１のものより、高いＮＯｘ浄化率を示しており、金
属酸化物を有する上触媒層の形成がＮＯｘ浄化率の向上
に効を奏することがわかる。また、実施例１０，１１の
ようにエージングを施した場合でも、同じくエージング
を施した比較例２よりもＮＯｘ浄化率が高くなってお
り、実施例のものはエージングにも耐え得ることがわか
る。According to Table 1, all of Examples 1 to 9 show a higher NOx purification rate than that of Comparative Example 1, and the formation of the upper catalyst layer containing a metal oxide improves the NOx purification rate. You can see that it works. Further, even when aging is performed as in Examples 10 and 11, the NOx purification rate is higher than in Comparative Example 2 in which aging is also performed, and it can be seen that the Examples can withstand aging.
【００４５】＜上下の触媒層における上触媒層の比率に
ついて＞
次の触媒材料を用い、上触媒層の割合を互いに異なるも
のにした各排気ガス浄化用触媒を実施例１と同様の方法
によって製造し、触媒入口の排気ガス温度３００℃での
ＮＯｘ浄化率を先の場合と同様の方法によって求めた。
この場合、ハニカムへの触媒材料の全ウォッシュコート
量は１５重量％、３０重量％及び４５重量％の３種類と
した。<Regarding Ratio of Upper Catalyst Layers in Upper and Lower Catalyst Layers> Using the following catalyst materials, respective exhaust gas purifying catalysts having different ratios of upper catalyst layers from each other were produced by the same method as in Example 1. Then, the NOx purification rate at an exhaust gas temperature of 300 ° C. at the catalyst inlet was obtained by the same method as the above case.
In this case, the total washcoat amount of the catalyst material on the honeycomb was set to three kinds of 15% by weight, 30% by weight and 45% by weight.
【００４６】−下触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
活性種；Ｐｔ：Ｉｒ：Ｒｈ＝３．３wt％：０．５５wt
％：０．０５wt％
−上触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
活性種；Ｐｔ：Ｉｒ：Ｒｈ＝１．７wt％：０．２７wt
％：０．０２５wt％
酸化物；ＣｅＯ2（５０wt％）-Lower catalyst layer material-Base material: H type ZSM-5 (Cayvan ratio 70) Active species; Pt: Ir: Rh = 3.3 wt%: 0.55 wt
%: 0.05 wt% -Upper catalyst layer material-Base material; H type ZSM-5 (Cayban ratio 70) Active species; Pt: Ir: Rh = 1.7 wt%: 0.27 wt
%: 0.025 wt% oxide; CeO 2 (50 wt%)
【００４７】結果は、ウォッシュコート量１５重量％の
ものが図２に、３０重量％のものが図３に、４５重量％
のものが図４にそれぞれ示されている。これらによれ
ば、上触媒層の比率は１５〜８５重量％が好ましいこと
がわかる。なお、全ウォッシュコート量は１５〜５０重
量％が好ましい。The results are shown in FIG. 2 for the washcoat amount of 15% by weight, and for 45% by weight in the case of 30% by weight.
Are shown in FIG. 4, respectively. According to these, it is understood that the ratio of the upper catalyst layer is preferably 15 to 85% by weight. The total washcoat amount is preferably 15 to 50% by weight.
【００４８】＜貴金属の担持量について＞
次の触媒材料を用い、上触媒層における貴金属（活性
種）の総量を３ｇ／ｌとし、下触媒層における貴金属担
持量を互いに異なるものにした各排気ガス浄化用触媒を
実施例１と同様の方法によって製造し、触媒入口の排気
ガス温度３００℃でのＮＯｘ浄化率を先の場合と同様の
方法によって求めた。この場合、上下の触媒層における
上触媒層の比率は６０重量％とした。<Regarding Carrying Amount of Noble Metals> The following catalyst materials were used, and the total amount of noble metals (active species) in the upper catalyst layer was 3 g / l, and the noble metal supporting amounts in the lower catalyst layer were different from each other. A purification catalyst was manufactured by the same method as in Example 1, and the NOx purification rate at an exhaust gas temperature of 300 ° C. at the catalyst inlet was determined by the same method as the above case. In this case, the ratio of the upper catalyst layer in the upper and lower catalyst layers was 60% by weight.
【００４９】−下触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝３．３wt％：０．５５wt
％：０．０５wt％
−上触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝１．７wt％：０．２７wt
％：０．０２５wt％
酸化物；ＣｅＯ2（４０wt％）-Lower catalyst layer material-Base material: H type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 3.3 wt%: 0.55 wt
%: 0.05 wt% -Upper catalyst layer material-Base material: H-type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 1.7 wt%: 0.27 wt
%: 0.025 wt% oxide; CeO 2 (40 wt%)
【００５０】結果は図５に示されている。同図によれ
ば、下触媒層における貴金属担持量は１〜８ｇ／ｌが好
ましいことがわかる。The results are shown in FIG. According to the figure, it is understood that the amount of precious metal supported in the lower catalyst layer is preferably 1 to 8 g / l.
【００５１】次に上記触媒材料を用い、下触媒層におけ
る貴金属の総量を４．５ｇ／ｌとし、上触媒層における
貴金属担持量を互いに異なるものにした各排気ガス浄化
用触媒を実施例１と同様の方法によって製造し、触媒入
口の排気ガス温度３００℃でのＮＯｘ浄化率を先の場合
と同様の方法によって求めた。この場合、上下の触媒層
における上触媒層の比率は６０重量％とした。結果は図
６に示されている。同図によれば、上触媒層における貴
金属担持量は０．５〜６ｇ／ｌが好ましいことがわか
る。Next, using the above-mentioned catalyst material, the total amount of noble metals in the lower catalyst layer was set to 4.5 g / l, and the amounts of supported noble metals in the upper catalyst layer were made different from each other. A NOx purification rate at a catalyst inlet exhaust gas temperature of 300 ° C. was obtained by the same method as above. In this case, the ratio of the upper catalyst layer in the upper and lower catalyst layers was 60% by weight. Results are shown in FIG. According to the figure, it is found that the amount of precious metal supported on the upper catalyst layer is preferably 0.5 to 6 g / l.
【００５２】次に上記触媒材料を用い、上触媒層におけ
る貴金属担持量と下触媒層における貴金属担持量との比
率を１：１として、上下の触媒層合わせた貴金属の総量
を互いに異なるものにした各排気ガス浄化用触媒を実施
例１と同様の方法によって製造し、触媒入口の排気ガス
温度３００℃でのＮＯｘ浄化率を先の場合と同様の方法
によって求めた。上下の触媒層における上触媒層の比率
は６０重量％である。結果は図７に示されている。同図
によれば、上触媒層における貴金属担持量は０．５〜６
ｇ／ｌが好ましいことがわかる。Next, using the above-mentioned catalyst material, the ratio of the amount of precious metal carried in the upper catalyst layer to the amount of precious metal carried in the lower catalyst layer was set to 1: 1 so that the total amount of precious metals in the upper and lower catalyst layers was different from each other. Each exhaust gas purification catalyst was produced by the same method as in Example 1, and the NOx purification rate at the exhaust gas temperature of the catalyst inlet of 300 ° C. was determined by the same method as above. The ratio of the upper catalyst layer in the upper and lower catalyst layers is 60% by weight. The results are shown in Figure 7. According to the figure, the amount of precious metal supported in the upper catalyst layer is 0.5 to 6
It can be seen that g / l is preferred.
【００５３】＜上触媒層における金属酸化物量について
＞
次の触媒材料を用い、上触媒層における金属酸化物の種
類及び比率を互いに異なるものにした各排気ガス浄化用
触媒を実施例１と同様の方法によって製造し、触媒入口
の排気ガス温度３００℃でのＮＯｘ浄化率を先の場合と
同様の方法によって求めた。この場合、上下の触媒層に
おける上触媒層の比率は６０重量％と８０重量％の２種
類とした。<Regarding Amount of Metal Oxide in Upper Catalyst Layer> The same exhaust gas purifying catalyst as in Example 1 was prepared by using the following catalyst materials and different kinds and ratios of metal oxides in the upper catalyst layer. The NOx purification rate at the catalyst inlet exhaust gas temperature of 300 ° C. was determined by the same method as in the above case. In this case, the ratio of the upper catalyst layer in the upper and lower catalyst layers was set to 60% by weight and 80% by weight.
【００５４】−下触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝３．３wt％：０．５５wt
％：０．０５wt％
−上触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝１．７wt％：０．２７wt
％：０．０２５wt％
酸化物；ＣｅＯ2又はＡｌ2Ｏ3又はＴｉＯ2（４０wt％）-Lower catalyst layer material-Base material: H type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 3.3 wt%: 0.55 wt
%: 0.05 wt% -Upper catalyst layer material-Base material: H-type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 1.7 wt%: 0.27 wt
%: 0.025 wt% oxide; CeO 2 or Al 2 O 3 or TiO 2 (40 wt%)
【００５５】結果は、上触媒層の比率は６０重量％のも
のが図８に、８０重量％のものが図９にそれぞれ示され
ている。同図によれば、金属酸化物としてはＣｅＯ2が
最も良いこと、金属酸化物の比率としては５〜９０重量
％の範囲で適宜設定できることがわかる。The results are shown in FIG. 8 for the proportion of the upper catalyst layer of 60% by weight and in FIG. 9 for the proportion of 80% by weight. According to the figure, CeO 2 is the best as the metal oxide, and the ratio of the metal oxide can be appropriately set within the range of 5 to 90% by weight.
【００５６】＜上触媒層における活性種担持量と金属酸
化物量との関係＞
次の触媒材料を用い、上触媒層における活性種担持量及
びＣｅＯ2の比率を互いに異なるものにした各排気ガス
浄化用触媒を実施例１と同様の方法によって製造し、触
媒入口の排気ガス温度３００℃でのＮＯｘ浄化率を先の
場合と同様の方法によって求めた。この場合、上下の触
媒層における上触媒層の比率は６０重量％とし、下触媒
層における活性種担持量は４．５ｇ／ｌとした。<Relationship Between Amount of Active Species Supported and Amount of Metal Oxide in Upper Catalyst Layer> Exhaust gas purification in which the following catalyst materials are used, and the amounts of supported active species and CeO 2 in the upper catalyst layer are made different from each other. The catalyst for use was manufactured by the same method as in Example 1, and the NOx purification rate at an exhaust gas temperature of 300 ° C. at the catalyst inlet was determined by the same method as the above case. In this case, the ratio of the upper catalyst layer in the upper and lower catalyst layers was 60% by weight, and the amount of active species supported in the lower catalyst layer was 4.5 g / l.
【００５７】−下触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝３．３wt％：０．５５wt
％：０．０５wt％
−上触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝１．７wt％：０．２７wt
％：０．０２５wt％
酸化物；ＣｅＯ2（４０wt％）-Lower catalyst layer material-Base material: H type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 3.3 wt%: 0.55 wt
%: 0.05 wt% -Upper catalyst layer material-Base material: H-type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 1.7 wt%: 0.27 wt
%: 0.025 wt% oxide; CeO 2 (40 wt%)
【００５８】結果は図１０に示されている。同図によれ
ば、上触媒層における活性種担持量が少ないときには金
属酸化物量も少なくする方が良いこと、但し、活性種担
持量３ｇ／ｌの場合は、金属酸化物量の多少にあまり影
響されないことがわかる。The results are shown in FIG. According to the figure, when the amount of active species supported in the upper catalyst layer is small, it is better to reduce the amount of metal oxides. However, when the amount of active species supported is 3 g / l, there is little effect on the amount of metal oxides. I understand.
【００５９】＜排気ガス浄化率の温度特性（従来例との
比較）＞
次の構成の実施例触媒と比較例触媒とを先の実施例
１に記載の製法に倣って製造し、各触媒入口温度でのＮ
Ｏｘ浄化率及びＨＣ浄化率を先の場合と同様の方法によ
って求めた。<Temperature Characteristics of Exhaust Gas Purification Rate (Comparison with Conventional Example)> Example catalysts and comparative example catalysts having the following configurations were produced according to the production method described in Example 1, and each catalyst inlet was manufactured. N at temperature
The Ox purification rate and the HC purification rate were determined by the same method as in the above case.
【００６０】（実施例触媒）
−下触媒層−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝３．３wt％：０．５５wt
％：０．０５wt％
−上触媒層材料−
母 材；Ｈ型ＺＳＭ−５（ケイバン比７０）
貴金属；Ｐｔ：Ｉｒ：Ｒｈ＝２．２wt％：０．３６wt
％：０．０３wt％
酸化物；ＣｅＯ2（４０wt％）
−上触媒層と下触媒層との比率−
上触媒層：下触媒層＝１：１(Example catalyst) -Lower catalyst layer-Base material: H-type ZSM-5 (Cayvan ratio 70) Noble metal; Pt: Ir: Rh = 3.3 wt%: 0.55 wt
%: 0.05 wt% -Upper catalyst layer material-Base material; H type ZSM-5 (Cayban ratio 70) Noble metal; Pt: Ir: Rh = 2.2 wt%: 0.36 wt
%: 0.03 wt% Oxide; CeO 2 (40 wt%)-Ratio of upper catalyst layer to lower catalyst layer-Upper catalyst layer: lower catalyst layer = 1: 1
【００６１】結果は図１１に示されている。実施例触媒
ではＮＯｘ浄化活性及びＨＣ浄化活性が共に比較例触
媒よりも高温側に現れている。これは、上触媒層に混
入されているＣｅＯ2がＨＣの完全酸化を抑制し、ＮＯ
ｘの分解に有効なＨＣ燃焼中間体の生成に寄与したため
と認められる。The results are shown in FIG. In the example catalyst, both the NOx purification activity and the HC purification activity appear on the higher temperature side than the comparative example catalyst. This is because CeO 2 mixed in the upper catalyst layer suppresses complete oxidation of HC,
It is considered that it contributed to the production of an HC combustion intermediate effective for decomposing x.
【図１】排気ガス浄化用触媒の構造を示す断面図FIG. 1 is a sectional view showing the structure of an exhaust gas purifying catalyst.
【図２】ウォッシュコート１５重量％の場合における上
触媒層の比率とＮＯｘ浄化率との関係を示すグラフ図FIG. 2 is a graph showing the relationship between the ratio of the upper catalyst layer and the NOx purification rate when the washcoat is 15% by weight.
【図３】ウォッシュコート３０重量％の場合における上
触媒層の比率とＮＯｘ浄化率との関係を示すグラフ図FIG. 3 is a graph showing the relationship between the ratio of the upper catalyst layer and the NOx purification rate when the washcoat is 30% by weight.
【図４】ウォッシュコート４５重量％の場合における上
触媒層の比率とＮＯｘ浄化率との関係を示すグラフ図FIG. 4 is a graph showing the relationship between the ratio of the upper catalyst layer and the NOx purification rate when the washcoat is 45% by weight.
【図５】下触媒層の貴金属担持量とＮＯｘ浄化率との関
係を示すグラフ図FIG. 5 is a graph showing the relationship between the amount of precious metal carried in the lower catalyst layer and the NOx purification rate.
【図６】上触媒層の貴金属担持量とＮＯｘ浄化率との関
係を示すグラフ図FIG. 6 is a graph showing the relationship between the amount of precious metal carried in the upper catalyst layer and the NOx purification rate.
【図７】貴金属総担持量とＮＯｘ浄化率との関係を示す
グラフ図FIG. 7 is a graph showing the relationship between the total amount of precious metals carried and the NOx purification rate.
【図８】上触媒層の比率が６０重量％のときの金属酸化
物量とＮＯｘ浄化率との関係を示すグラフ図FIG. 8 is a graph showing the relationship between the amount of metal oxides and the NOx purification rate when the ratio of the upper catalyst layer is 60% by weight.
【図９】上触媒層の比率が８０重量％のときの金属酸化
物量とＮＯｘ浄化率との関係を示すグラフ図FIG. 9 is a graph showing the relationship between the amount of metal oxides and the NOx purification rate when the ratio of the upper catalyst layer is 80% by weight.
【図１０】上触媒層における活性種担持量と金属酸化物
量との関係をＮＯｘ浄化率についてみたグラフ図FIG. 10 is a graph showing the relationship between the amount of active species supported and the amount of metal oxides in the upper catalyst layer, with respect to the NOx purification rate.
【図１１】実施例触媒及び比較例触媒の排気ガス浄化率
の温度特性を示すグラフ図FIG. 11 is a graph showing temperature characteristics of exhaust gas purification rates of the example catalyst and the comparative example catalyst.
１ 触媒担体 ２ 下触媒層 ３ 上触媒層 1 Catalyst carrier 2 Lower catalyst layer 3 Upper catalyst layer
───────────────────────────────────────────────────── フロントページの続き (72)発明者 市川 智士 広島県安芸郡府中町新地３番１号 マツ ダ株式会社内 (56)参考文献 特開 平５−168939（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B01J 21/00 - 38/74 B01D 53/86,53/94 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Ichikawa 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (56) Reference JP 5-168939 (JP, A) (58) Survey Areas (Int.Cl. 7 , DB name) B01J 21/00-38/74 B01D 53 / 86,53 / 94
Claims (5)
ていて、排気ガス中のＮＯｘをＨＣの存在下で分解する
排気ガス浄化用触媒であって、 上記上層が下層に比べてＨＣ酸化能が低い触媒によって
形成されており、 上記上層が活性種として貴金属を有し、且つ金属酸化物
が混合されてなる触媒によって形成され、 上記下層が金属含有シリケートに貴金属を活性種として
担持させた触媒によって形成され ていることを特徴とす
る排気ガス浄化用触媒。。1. A catalyst for purifying exhaust gas, which comprises upper and lower two catalyst layers on a catalyst carrier and decomposes NOx in exhaust gas in the presence of HC, wherein the upper layer is lower than the lower layer. It is formed by a catalyst having a low HC oxidizing ability , the upper layer has a noble metal as an active species, and a metal oxide.
Is formed by a catalyst consisting of a mixture of the above and the above-mentioned lower layer containing a noble metal as an active species in the metal-containing silicate.
An exhaust gas purifying catalyst, which is formed of a supported catalyst. .
おいて、 上記上層が金属酸化物とＨ型金属含有シリケートとの混
合物に上記貴金属を担持させてなる触媒によって形成さ
れているもの。2. The exhaust gas purifying catalyst according to claim 1 , wherein the upper layer is formed by a catalyst in which the noble metal is supported on a mixture of a metal oxide and an H-type metal-containing silicate.
ス浄化用触媒において、 上記上層の触媒が活性種としてＰｔを含み、金属酸化物
としてＣｅＯ 2 又はＡｌ 2 Ｏ 3 又はＴｉＯ 2 を含むもの。3. A catalyst for purifying exhaust gases according to claim 1 or claim 2, said upper layer of the catalyst comprises Pt as an active species, metal oxide
Containing CeO 2, Al 2 O 3 or TiO 2 .
ス浄化用触媒において、 上記下層の触媒が金属酸化物としてＡｌ 2 Ｏ 3 を含むも
の。 4. The exhaust gas according to claim 1 or 2.
In the catalyst for purifying sulfur, the lower layer catalyst contains Al 2 O 3 as a metal oxide.
of.
製造方法であって、 金属含有シリケートに貴金属を担持させてなる触媒を触
媒担体の表面にコーティングすることによって下層を形
成した後、該下層の上に金属酸化物とＨ型金属含有シリ
ケートとの混合物をコーティングし、該コーティング層
に貴金属を含浸によって担持させることを特徴とする排
気ガス浄化用触媒の製造方法。5. The method for producing an exhaust gas purifying catalyst according to claim 2, wherein a catalyst comprising a metal-containing silicate carrying a noble metal is coated on the surface of a catalyst carrier to form a lower layer, A method for producing an exhaust gas purifying catalyst, characterized in that the lower layer is coated with a mixture of a metal oxide and an H-type metal-containing silicate, and a noble metal is supported on the coating layer by impregnation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16789893A JP3427422B2 (en) | 1993-07-07 | 1993-07-07 | Exhaust gas purification catalyst and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16789893A JP3427422B2 (en) | 1993-07-07 | 1993-07-07 | Exhaust gas purification catalyst and method for producing the same |
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| Publication Number | Publication Date |
|---|---|
| JPH0724333A JPH0724333A (en) | 1995-01-27 |
| JP3427422B2 true JP3427422B2 (en) | 2003-07-14 |
Family
ID=15858106
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| JP3956437B2 (en) * | 1996-09-26 | 2007-08-08 | マツダ株式会社 | Exhaust gas purification catalyst |
| JP5310767B2 (en) * | 2011-03-29 | 2013-10-09 | トヨタ自動車株式会社 | Exhaust gas purification catalyst |
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| Publication number | Publication date |
|---|---|
| JPH0724333A (en) | 1995-01-27 |
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