JPH04161249A - Exhaust gas purification catalyst - Google Patents
Exhaust gas purification catalystInfo
- Publication number
- JPH04161249A JPH04161249A JP2284411A JP28441190A JPH04161249A JP H04161249 A JPH04161249 A JP H04161249A JP 2284411 A JP2284411 A JP 2284411A JP 28441190 A JP28441190 A JP 28441190A JP H04161249 A JPH04161249 A JP H04161249A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- catalyst
- layer containing
- exhaust gas
- activated alumina
- 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.)
- Pending
Links
- 239000003054 catalyst Substances 0.000 title claims abstract description 46
- 238000000746 purification Methods 0.000 title claims abstract description 7
- 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 31
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 12
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 11
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 29
- 239000010948 rhodium Substances 0.000 claims description 18
- 229910000510 noble metal Inorganic materials 0.000 claims description 10
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 4
- 230000006866 deterioration Effects 0.000 abstract description 6
- 239000010970 precious metal Substances 0.000 abstract description 5
- 229910045601 alloy Inorganic materials 0.000 abstract description 4
- 239000000956 alloy Substances 0.000 abstract description 4
- 230000015572 biosynthetic process Effects 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 230000003197 catalytic effect Effects 0.000 abstract 1
- 239000000843 powder Substances 0.000 description 13
- 239000002002 slurry Substances 0.000 description 12
- 239000007789 gas Substances 0.000 description 8
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 229910052684 Cerium Inorganic materials 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 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
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003426 co-catalyst Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 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
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、自動車等の内燃機関から排出される排ガス中
の有害成分である炭化水素（）Ｉｃ）、−酸化炭素（Ｃ
Ｏ）、窒素酸化物（Ｎｏ、）を効率良く浄化する排ガス
浄化用触媒に関する。Detailed Description of the Invention (Industrial Application Field) The present invention is directed to the treatment of hydrocarbons ()Ic), -carbon oxides (C
O), relates to an exhaust gas purification catalyst that efficiently purifies nitrogen oxides (No.).
（従来の技術） 従来、内燃機関から排出される排ガス中のＩＣ。(Conventional technology) Conventionally, ICs are found in exhaust gas emitted from internal combustion engines.
ＣＯ，ＮＯ□を浄化する排ガス浄化用触媒は種々提案さ
れている。Various exhaust gas purifying catalysts for purifying CO and NO□ have been proposed.
その中で、パラジウム（Ｐｄ）を白金（Ｐｔ）あるいは
ロジウム（Ｒｈ）と組み合わせて用いる触媒に関しては
、例えば、特開昭５８−１４６４４１号公報に見ぼれる
ように、Ｐｄが共存するｐｔあるいはＲｈと相互作用す
る事による触媒の性能劣化を防止するために、担体上に
Ｐｄを含む層と、ｐｔおよびＲｈを含む層とを分離して
形成するといったものがある。Among them, regarding catalysts that use palladium (Pd) in combination with platinum (Pt) or rhodium (Rh), for example, as seen in JP-A-58-146441, catalysts that use palladium (Pd) in combination with platinum (Pt) or rhodium (Rh) are In order to prevent performance deterioration of the catalyst due to interaction with the catalyst, a layer containing Pd and a layer containing pt and Rh are separately formed on the carrier.
（発明が解決しようとする課題）
しかしながら、このような排ガス浄化用触媒にあっては
、高温下で貴金属の熱拡散が起こると、第１層と第２層
の境界部においてＰｄとｐｔあるいはＲｈとの相互作用
が起こり触媒の活性の低下がおこるという問題がある。(Problem to be Solved by the Invention) However, in such an exhaust gas purification catalyst, when thermal diffusion of precious metals occurs at high temperatures, Pd and pt or Rh are mixed at the boundary between the first layer and the second layer. There is a problem in that interaction with the catalyst occurs and the activity of the catalyst decreases.
（課題を解決するための手段）
発明者は、高温下におけるＰｄと、ｐｔあるいはＲｈと
の合金化による触媒の性能劣化を防止するべく鋭意研究
の結果以下に述べる触媒構造を見出し、本発明を達成す
るに至った。(Means for Solving the Problems) As a result of intensive research, the inventor discovered the catalyst structure described below in order to prevent catalyst performance deterioration due to alloying of Pd and PT or Rh at high temperatures, and the present invention has been achieved. I have achieved this goal.
本発明の排ガス浄化用触媒の特徴は、Ｐｄを含有する触
媒層と、ｐｔおよび／またはＲｈを含有する触媒層との
間に貴金属触媒成分を含有しない第三の触媒層を形成さ
せる点にあり、具体的には、モノリス担体基材上にＰｄ
と活性アルミナを含んでなる第一層（担体側）と、貴金
属成分を含まず活性アルミナを含んでなる第二層と、Ｒ
ｈおよび／またはｐｔと活性アルミナを含んでなる第三
層（表面側）の三層構造を有することにある。A feature of the exhaust gas purifying catalyst of the present invention is that a third catalyst layer containing no noble metal catalyst component is formed between the catalyst layer containing Pd and the catalyst layer containing pt and/or Rh. , specifically, Pd on a monolithic carrier substrate.
and a first layer (carrier side) containing activated alumina; a second layer containing activated alumina and no noble metal component;
It has a three-layer structure with the third layer (surface side) containing h and/or pt and activated alumina.
本発明の触媒の製造方法としては、例えば、Ｐｄとアル
ミナを含むスラリーと、貴金属を含まずアルミナを含む
スラリーと、ｐｔあるいはＲｈとアルミナを含むスラリ
ーとを逐次モノリス担体基材上にコーティングする方法
がある。The method for producing the catalyst of the present invention includes, for example, a method in which a slurry containing Pd and alumina, a slurry containing alumina but not containing noble metals, and a slurry containing PT or Rh and alumina are sequentially coated on a monolithic carrier base material. There is.
モノリス担体基材としてはコージェライト等のセラミッ
ク製のものや、ステンレス等の金属製のものを使用する
ことが出来る。As the monolith carrier base material, a material made of ceramic such as cordierite or a material made of metal such as stainless steel can be used.
また、各触媒層には必要に応じて、希土類元素、バリウ
ム、ジルコニウム等の助触媒成分を添加することが出来
る。Furthermore, co-catalyst components such as rare earth elements, barium, zirconium, etc. can be added to each catalyst layer as needed.
（作 用）
本発明の触媒においては、Ｐｄと、ｐｔおよび／または
Ｒｈとの相互作用が貴金属を含まない中間層によって防
止されており、高温使用時における合金の生成が抑制さ
れる。(Function) In the catalyst of the present invention, the interaction between Pd and pt and/or Rh is prevented by the intermediate layer that does not contain a noble metal, and the formation of an alloy during high-temperature use is suppressed.
また、中間層を活性アルミナを主成分とする層にする事
によって、貴金属成分が中間層に熱拡散した場合にも、
貴金属の分散性がある程度維持される。In addition, by making the intermediate layer a layer mainly composed of activated alumina, even if noble metal components thermally diffuse into the intermediate layer,
The dispersion of precious metals is maintained to some extent.
その結果、高温時においても触媒性能の低下が少なくな
る。As a result, there is less deterioration in catalyst performance even at high temperatures.
（実施例）
以下、この発明を、実施例、比較例及び、試験例により
説明する。(Examples) The present invention will be described below with reference to Examples, Comparative Examples, and Test Examples.
１隻貫上
セリウムを３重量％担持した活性アルミナ粉末を撹拌し
ながら、ジニトロジアンミンパラジウム溶液を噴霧し、
乾燥した後、空気中４００°Ｃで２時間焼成してＰｄ担
持量２．０重量％のＰｄ担持アルミナを得た。While stirring activated alumina powder carrying 3% by weight of cerium, a dinitrodiammine palladium solution was sprayed,
After drying, it was calcined in air at 400° C. for 2 hours to obtain Pd-supported alumina with a Pd-supported amount of 2.0% by weight.
また、硝酸ロジウム溶液を用いて、同様の方法にて、Ｒ
ｈ担持量０．８重量％のＲｈ担持アルミナ粉末を調製し
た。In addition, using a rhodium nitrate solution, R
Rh-supported alumina powder with a supported amount of 0.8% by weight was prepared.
Ｐｄ担持アルミナ粉末を１３９３ｇ 、酸化セリウム粉
末３８４ｇ、アルミナゾル２２２３ｇを磁性ボー・ルミ
ルに投入し、混合粉砕してスラリー液を得た。1,393 g of Pd-supported alumina powder, 384 g of cerium oxide powder, and 2,223 g of alumina sol were placed in a magnetic ball mill, mixed and pulverized to obtain a slurry liquid.
このスラリーに必要に応じて水を加え粘度を調整した後
、コージェライト質モノリス担体（１，３Ｌ）を浸漬し
、引き上げた後空気流にてセル内の余剰のスラリーを取
り除いて乾燥し、次いで４００℃で２時間焼成して、第
一層を形成させた。After adjusting the viscosity by adding water to this slurry as necessary, a cordierite monolithic carrier (1,3 L) was immersed in the slurry, and after being pulled up, the excess slurry inside the cell was removed with an air stream and dried. The first layer was formed by firing at 400° C. for 2 hours.
つぎに、Ｐｄ担持粉末の代わりに、Ｐｄを担持しないア
ルミナ粉末を用いた以外は上記と同様にして調製したス
ラリーを第一層が形成された担体に同様の方法でコーテ
ィングし第二層を形成させた。Next, a slurry prepared in the same manner as above except that alumina powder that does not support Pd was used instead of Pd-supported powder was coated on the carrier on which the first layer was formed in the same manner to form a second layer. I let it happen.
さらに、Ｒｈ担持粉末を用いた以外は同様にして調製し
たスラリーを第一層、第二層が形成された担体に同様の
方法でコーティングし第三層を形成させ三層構造を有す
る触媒１を得た。Furthermore, a slurry prepared in the same manner except that Rh-supported powder was used was coated on the carrier on which the first and second layers were formed to form a third layer, thereby obtaining catalyst 1 having a three-layer structure. Obtained.
各触媒層のウォッシュコート量は、第一層が８０ｇ／Ｌ
−担体、第二層が８０ｇ／Ｌ−担体、第三層が４０ｇ／
Ｌ−担体であった。The amount of wash coat for each catalyst layer is 80g/L for the first layer.
- Carrier, second layer: 80 g/L - Carrier, third layer: 40 g/L
It was L-carrier.
北較孤土
実施例１と同様の方法にて、Ｐｄ担持量１．０重量％の
Ｐｄ担持アルミナを調製した。次いで、実施例１と同様
のコーティング操作を２回繰り返しＰｄを含む第一層を
形成させた。Pd-supported alumina with a Pd-supported amount of 1.0% by weight was prepared in the same manner as in Example 1. Next, the same coating operation as in Example 1 was repeated twice to form a first layer containing Pd.
さらに、実施例１と同様にして、Ｒｈ含有量（第二層）
を形成させ、二層構造を有する触媒２を、得た。Furthermore, in the same manner as in Example 1, Rh content (second layer)
was formed to obtain catalyst 2 having a two-layer structure.
各触媒のウォッシュコート量は、第一層が１６０ｇ／Ｌ
−担体、第二層が４０ｇ／Ｌ−担体であった。The wash coat amount of each catalyst is 160g/L for the first layer.
-Carrier, second layer was 40g/L-carrier.
実施貫Ｉ
セリウムを７重量％、バリウムを３重量％担持した活性
アルミナ粉末を撹拌しながら、ジニトロジアンミンバラ
５ジウム溶液を噴霧し、乾燥した後、空気中４００°Ｃ
で２時間焼成してＰｄ担持量２．０重量％のＰｄ担持ア
ルミナを得た。Implementation I Spray dinitrodiammine baradium solution while stirring the activated alumina powder carrying 7% by weight of cerium and 3% by weight of barium, dry it, and then hold it at 400°C in the air.
After firing for 2 hours, Pd-supported alumina with a Pd support amount of 2.0% by weight was obtained.
また、ジニトロジアンミン白金溶液を用いて同様に、ｐ
ｔ担持量２．０重量％のｐｔ担持アルミナ粉末を調製し
た。Similarly, using dinitrodiammine platinum solution, p
A PT-supported alumina powder with a t-support amount of 2.0% by weight was prepared.
これらの各アルミナ粉末を用いて、実施例１と同様の方
法で、Ｐｄを含む第一層、貴金属を含まない第二層、ｐ
ｔを含む第三層を形成させ、三層構造を有する触媒３を
得た。Using each of these alumina powders, a first layer containing Pd, a second layer not containing noble metal, and p
A third layer containing t was formed to obtain a catalyst 3 having a three-layer structure.
各触媒層のウォッシュコート量は、第一層が８０ｇ／Ｌ
−担体、第二層が８０ｇルー担体、第三層が４０ｇ／Ｌ
−担体であった。The amount of wash coat for each catalyst layer is 80g/L for the first layer.
-Carrier, second layer is 80g - carrier, third layer is 40g/L
- It was a carrier.
止較拠り
実施例２と同様の方法にて、Ｐｄ担持量１．０重量％の
Ｐｄ担持アルミナを調製した。次いで、比較例１と同様
にコーティング操作を２回繰り返しＰｄを含む第一層を
形成させた。Based on the comparison, Pd-supported alumina with a Pd support amount of 1.0% by weight was prepared in the same manner as in Example 2. Next, the coating operation was repeated twice in the same manner as in Comparative Example 1 to form a first layer containing Pd.
さらに、実施例２と同様にして、ｐｔ含有層（第二層）
を形成させ、二層構造を有する触媒４を得た。Furthermore, in the same manner as in Example 2, a pt-containing layer (second layer)
was formed to obtain a catalyst 4 having a two-layer structure.
各触媒層のウォッシュコート量は、第一層が１６０ｇ／
Ｌ−担体、第二層が４０ｇ／Ｌ−担体であった。The amount of wash coat for each catalyst layer is 160g/1 for the first layer.
L-carrier, second layer was 40g/L-carrier.
夫施貰１
ｐｔ担持量２．０重量％のｐｔ担持アルミナ粉末６９６
ｇと、Ｒｈ担持量０．８重量％のＲｈ担持アルミナ粉末
６９６ｇ、酸化セリウム粉末３８４ｇ、アルミナゾル２
２２３ｇを磁性ボールミルに投入し、混合粉砕してスラ
リー液を得た。このスラリーを、実施例２と同様にして
第二層まで形成させたコート担体に塗布し第三層を形成
させ、Ｐｄを含む第一層、貴金属を含まない第二層、ｐ
ｔ及びＲｈを含む第三層からなる三層構造を有する触媒
５を得た。PT-supported alumina powder 696 with a PT-supported amount of 2.0% by weight
g, 696 g of Rh-supported alumina powder with a Rh-supported amount of 0.8% by weight, 384 g of cerium oxide powder, and alumina sol 2.
223 g was put into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid. This slurry was applied to the coated carrier on which up to the second layer had been formed in the same manner as in Example 2 to form a third layer.
A catalyst 5 having a three-layer structure consisting of a third layer containing t and Rh was obtained.
各触媒層のウォッシュコート量は、第一層が８０ｇルー
担体、第二層が８０ｇルー担体、第三層が４０ｇ／Ｌ−
担体であった。The wash coating amount of each catalyst layer is 80 g/L for the first layer, 80 g/L for the second layer, and 40 g/L for the third layer.
It was a carrier.
止較■ユ
実施例３と同様にして調製したＰｔ、 Ｒｈを含むスラ
リーを、比較例２と同様にしてＰｄ含有層（第一層）を
形成させたコート担体に塗布し第二層を形成させ、Ｐｄ
を含む第一層、ｐｔ及びＲｈを含む第二層からなる二層
構造を有する触媒６を得た。Comparison ■ A slurry containing Pt and Rh prepared in the same manner as in Example 3 was applied to a coated carrier on which a Pd-containing layer (first layer) was formed in the same manner as in Comparative Example 2 to form a second layer. Let, Pd
A catalyst 6 having a two-layer structure consisting of a first layer containing PT and a second layer containing PT and Rh was obtained.
各触媒層のウォッシュコート量は、第一層が１６０ｇル
ー担体、第二層が４０ｇルールーフあった。The amount of wash coating for each catalyst layer was 160 g of the first layer and 40 g of the second layer.
拭荻拠
実施例１．２．３ 、比較例１．２．３の各触媒（触媒
１〜６）につき、下記条件でエンジン耐久性能評価を行
い、耐久劣化触媒のＨＣ，ＣＯ，ＮＯＸ浄化率を測定し
た。For each catalyst (catalysts 1 to 6) of Example 1.2.3 and Comparative Example 1.2.3, engine durability performance was evaluated under the following conditions, and the HC, CO, NOx purification rate of the durable deteriorated catalyst was evaluated. was measured.
性能評価結果を第１表に示す。The performance evaluation results are shown in Table 1.
〈エンジン耐久条件〉
触媒入口排ガス温度 ７５０°Ｃ耐久時間
１００時間エンジン 排
気量２２００ｃｃ燃料 無鉛ガソ
リン耐久中入ロエミッション Ｃｏ ０．４〜０．
６％０□ ０．５±０．１％
ＮＯ約１００１０００
ｐｐ 約２５００ｐｐｍ
ＣＯ□１４．９±０．１％
〈性能評価条件〉
触媒入口排ガス温度 ４００°Ｃエンジン
排気量２０００ｃｃ燃料
無鉛ガソリン平均空燃比（制御中心値） １４
．６第１表
各試作触媒の排ガス浄化性能評価結果
（発明の効果）
以上説明したように、この発明によれば、モノリス担体
表面に形成される触媒成分層を、Ｐｄと活性アルミナを
含んでなる第一層（担体側）と、貴金属成分を含まず活
性アルミナを含んでなる第二層と、Ｒｈおよび／または
ｐｔと活性アルミナを含んだ第三層（表面側）の三層構
造とした事により、高温使用時におけるＰｄとＲｈある
いはｐｔとの合金の生成が抑制され、中間層を活性アル
ミナを主成分とする層にした事によって、貴金属触媒成
分が中間層に熱拡散した場合にも、貴金属の分散性があ
る程度維持されるため、高温時においても性能低下の少
ない触媒を得ることが出来る。<Engine durability conditions> Catalyst inlet exhaust gas temperature 750°C durability time
100 hour engine displacement 2200cc Fuel unleaded gasoline durable medium low emission Co 0.4~0.
6%0□ 0.5±0.1% NO approx. 1001000 pp approx. 2500ppm CO□14.9±0.1% <Performance evaluation conditions> Catalyst inlet exhaust gas temperature 400°C engine
Displacement 2000cc fuel
Unleaded gasoline average air-fuel ratio (control center value) 14
．． 6 Table 1 Exhaust gas purification performance evaluation results of each prototype catalyst (effects of the invention) As explained above, according to the present invention, the catalyst component layer formed on the surface of the monolithic support is made of a layer containing Pd and activated alumina. It has a three-layer structure: the first layer (carrier side), the second layer containing activated alumina without containing noble metal components, and the third layer (surface side) containing Rh and/or PT and activated alumina. This suppresses the formation of alloys between Pd and Rh or PT during high-temperature use, and by making the intermediate layer a layer mainly composed of activated alumina, even when the noble metal catalyst component thermally diffuses into the intermediate layer, Since the dispersibility of the noble metal is maintained to some extent, it is possible to obtain a catalyst with little performance deterioration even at high temperatures.
特許出願人 日産自動車株式会社Patent applicant: Nissan Motor Co., Ltd.
Claims (1)
種、並びに活性アルミナを含んでなるモノリス型排ガス
浄化用触媒において、モノリス担体表面に形成された活
性アルミナを含む触媒層が、その厚み方向で三層に分割
されており、第一層（担体側）にパラジウムを含み、中
間層は貴金属成分を含まず、第三層（表面側）は白金お
よびロジウムの少なくとも１種を含むことを特徴とする
排ガス浄化用触媒。1. Palladium and at least one of platinum and rhodium
In a monolithic exhaust gas purification catalyst comprising seeds and activated alumina, the catalyst layer containing activated alumina formed on the surface of the monolithic carrier is divided into three layers in the thickness direction. ) contains palladium, the middle layer does not contain a noble metal component, and the third layer (surface side) contains at least one of platinum and rhodium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2284411A JPH04161249A (en) | 1990-10-24 | 1990-10-24 | Exhaust gas purification catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2284411A JPH04161249A (en) | 1990-10-24 | 1990-10-24 | Exhaust gas purification catalyst |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04161249A true JPH04161249A (en) | 1992-06-04 |
Family
ID=17678219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2284411A Pending JPH04161249A (en) | 1990-10-24 | 1990-10-24 | Exhaust gas purification catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04161249A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08168675A (en) * | 1994-12-16 | 1996-07-02 | Toyota Motor Corp | Catalyst for purifying exhaust gas |
-
1990
- 1990-10-24 JP JP2284411A patent/JPH04161249A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08168675A (en) * | 1994-12-16 | 1996-07-02 | Toyota Motor Corp | Catalyst for purifying exhaust gas |
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