JPH0568888A - Waste gas cleaning catalyst - Google Patents
Waste gas cleaning catalystInfo
- Publication number
- JPH0568888A JPH0568888A JP3234669A JP23466991A JPH0568888A JP H0568888 A JPH0568888 A JP H0568888A JP 3234669 A JP3234669 A JP 3234669A JP 23466991 A JP23466991 A JP 23466991A JP H0568888 A JPH0568888 A JP H0568888A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- catalyst layer
- nox
- catalyst
- waste gas
- 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 133
- 239000002912 waste gas Substances 0.000 title abstract 7
- 238000004140 cleaning Methods 0.000 title abstract 5
- 229910021536 Zeolite Inorganic materials 0.000 claims abstract description 25
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000010457 zeolite Substances 0.000 claims abstract description 25
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 17
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 23
- 238000000034 method Methods 0.000 abstract description 13
- 239000004215 Carbon black (E152) Substances 0.000 abstract 1
- 229930195733 hydrocarbon Natural products 0.000 abstract 1
- 150000002430 hydrocarbons Chemical class 0.000 abstract 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 204
- 239000007789 gas Substances 0.000 description 91
- 238000000746 purification Methods 0.000 description 53
- 239000010949 copper Substances 0.000 description 25
- 238000012360 testing method Methods 0.000 description 21
- 238000005342 ion exchange Methods 0.000 description 15
- 238000002485 combustion reaction Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 239000011230 binding agent Substances 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 229910018967 Pt—Rh Inorganic materials 0.000 description 4
- 230000004913 activation Effects 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910052680 mordenite Inorganic materials 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 229910052703 rhodium Inorganic materials 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 description 1
- 229910052878 cordierite Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 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 1
- -1 etc. Chemical compound 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、リーン燃焼エンジン等
各種エンジンの排気ガス中のＮＯｘ（窒素酸化物）を除
去する排気ガス浄化用触媒に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying catalyst for removing NOx (nitrogen oxide) in the exhaust gas of various engines such as lean burn engines.
【０００２】[0002]
【従来の技術】近年、燃料消費率の低いリーン燃焼エン
ジンの開発が進められている。このリーン燃焼エンジン
を搭載した自動車は、従来のディーゼルエンジンと同
様、エンジン燃焼室を酸素過剰雰囲気下（リーン）に置
いて運転されている。その際、有毒ガスであるＮＯｘが
エンジンから多量に排出されるため、このＮＯｘを除去
し大気中への放出を防がねばならない。2. Description of the Related Art In recent years, the development of lean-burn engines with low fuel consumption has been underway. An automobile equipped with this lean combustion engine is operated with the engine combustion chamber placed in an excess oxygen atmosphere (lean), as in the case of a conventional diesel engine. At this time, a large amount of NOx, which is a toxic gas, is discharged from the engine, so this NOx must be removed to prevent its release into the atmosphere.
【０００３】従来、排気ガス中のＮＯｘを除去する技術
としては、主に、Ｐｔ−Ｒｈ系等の三元触媒を用いる方
法、アンモニア，尿素等による選択的還元法、および各
種吸着剤でＮＯｘを吸着するＮＯｘ吸収法がある。とこ
ろが、上記選択的還元法では、装置が大型であるという
問題があり、さらにアンモニアが大気中に排出されて２
次公害を起こすという問題があった。また、上記ＮＯｘ
吸収法では、吸着剤に吸着したＮＯｘを水洗い等で後処
理しなければならないという問題があった。しかも、上
記３つの従来方法では、酸素過剰雰囲気下においては効
果を発揮できず、ＮＯｘを充分に除去できないという問
題があった。Conventionally, as a technique for removing NOx in exhaust gas, a method using a three-way catalyst such as Pt-Rh system, a selective reduction method with ammonia, urea, etc., and NOx with various adsorbents have been mainly used. There is a NOx absorption method of adsorbing. However, in the above-mentioned selective reduction method, there is a problem that the apparatus is large, and further, ammonia is discharged into the atmosphere and
There was a problem of causing next pollution. In addition, the above NOx
The absorption method has a problem that NOx adsorbed on the adsorbent must be post-treated by washing with water or the like. Moreover, the above-mentioned three conventional methods have a problem in that the effect cannot be exhibited in an oxygen excess atmosphere and NOx cannot be sufficiently removed.
【０００４】そこで、ＮＯｘを効果的に除去できる排気
ガス浄化用触媒として、ゼオライトに銅をイオン交換担
持してなる銅イオン交換ゼオライトや、γ−アルミナが
発明され、実験室段階で９０％を越えるＮＯｘ浄化率を
得ることができた。Therefore, as an exhaust gas purifying catalyst capable of effectively removing NOx, a copper ion-exchanged zeolite in which copper is ion-exchanged and supported on a zeolite and γ-alumina have been invented, and the amount exceeds 90% in a laboratory stage. The NOx purification rate could be obtained.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、実際に
走行する自動車、いわゆる実車においては、運転条件が
刻々と変化するとともに、搭載されるエンジンにも様々
な種類がある。そのため、上記銅イオン交換ゼオライト
およびγ−アルミナの排気ガス浄化用触媒は、実車にお
いては良い効果を示していない。その理由としては、次
の３つの点が考えられる。However, in an actually traveling automobile, that is, a so-called actual automobile, the operating conditions change every moment, and there are various types of engines to be mounted. Therefore, the above-mentioned catalyst for purifying exhaust gas of copper ion-exchanged zeolite and γ-alumina does not show a good effect in an actual vehicle. There are three possible reasons for this.
【０００６】実験室においてＮＯｘ除去が可能な温度
（活性温度）の条件が、実車の排気ガスの温度条件と異
なる。The temperature conditions (NOx) at which NOx can be removed in the laboratory are different from the temperature conditions of the exhaust gas of the actual vehicle.
【０００７】実験室のリグテストのガス組成と実車の
排気ガスの組成とが若干異なる。The gas composition of the rig test in the laboratory and the composition of the exhaust gas of the actual vehicle are slightly different.
【０００８】実験室のリグテストのガスの流速が、実
車の排気ガスの流速より遅い。The gas flow velocity of the rig test in the laboratory is slower than the exhaust gas flow velocity of the actual vehicle.
【０００９】本発明はこのような諸点に鑑みてなされた
もので、その目的とするところは、アイドルアップ時か
ら高速走行時まで排気ガスの広い温度域でＮＯｘの浄化
率を高くし、自動車の様々なエンジンに実用化させ得る
排気ガス浄化用触媒を提供しようとするものである。The present invention has been made in view of the above points. An object of the present invention is to increase the NOx purification rate in a wide temperature range of exhaust gas from idle up to high-speed running, and An object of the present invention is to provide an exhaust gas purifying catalyst that can be put to practical use in various engines.
【００１０】[0010]
【課題を解決するための手段】上記の目的を達成するた
め、請求項１記載の発明は、排気ガスの排気路に設けら
れた排気ガス浄化用触媒であって、担体上に形成され排
気ガスの低温時にＮＯｘを浄化しかつＨＣと反応する貴
金属を含む触媒からなる第１触媒層と、この第１触媒層
の上層に形成され排気ガスの高温時にＮＯｘを浄化する
ゼオライトからなる第２触媒層とを備える構成とするも
のである。In order to achieve the above object, the invention according to claim 1 is an exhaust gas purifying catalyst provided in an exhaust gas exhaust passage, the exhaust gas being formed on a carrier. First catalyst layer composed of a catalyst containing a noble metal that purifies NOx at low temperatures and reacts with HC, and a second catalyst layer formed on the first catalyst layer and composed of zeolite that purifies NOx at high temperatures of exhaust gas And a configuration including.
【００１１】請求項２記載の発明は、上記第１触媒層
を、貴金属が担持されたγ−アルミナからなる構成とす
るものである。According to a second aspect of the present invention, the first catalyst layer is composed of γ-alumina carrying a noble metal.
【００１２】請求項３記載の発明は、上記第１触媒層
を、貴金属が担持されたゼオライトからなる構成とする
ものである。According to a third aspect of the present invention, the first catalyst layer is made of a zeolite carrying a noble metal.
【００１３】[0013]
【作用】上記の構成により、請求項１記載の発明では、
第２触媒層を通過した排気ガス中のＨＣが、第１触媒層
の貴金属と反応して燃焼し、担体の温度を高めるため、
排気ガスの温度が低かったり、従来では担体温度が低く
なるような運転条件でも、第２触媒層は、ＮＯｘを浄化
することが可能な活性温度まで到達し、低温時の排気ガ
ス中のＮＯｘを浄化することになる。排気ガスが高温時
には、第２触媒層によりＮＯｘが浄化される。With the above construction, in the invention according to claim 1,
Since HC in the exhaust gas that has passed through the second catalyst layer reacts with the noble metal of the first catalyst layer and burns to raise the temperature of the carrier,
Even under operating conditions in which the temperature of exhaust gas is low or the carrier temperature is low in the past, the second catalyst layer reaches an activation temperature at which NOx can be purified, and NOx in exhaust gas at low temperature is removed. It will be purified. When the exhaust gas has a high temperature, NOx is purified by the second catalyst layer.
【００１４】[0014]
【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.
【００１５】図１および図２は、本発明の第１実施例に
係る排気ガス浄化用触媒を示す。この排気ガス浄化用触
媒Ａは、排気ガスの排気路１の途中に設けられており、
ハニカム担体２上に形成された第１触媒層３と、この第
１触媒層３の上層に形成された第２触媒層４とを備えて
いる。すなわち、上記ハニカム担体２の各孔２ａ内にお
いては、上記第１触媒層３と上記第２触媒層４とが層状
に形成されており、排気ガスは、各孔２ａ内を第２触媒
層４の表面に接しながら流れるようになっている。1 and 2 show an exhaust gas purifying catalyst according to a first embodiment of the present invention. The exhaust gas purifying catalyst A is provided in the middle of the exhaust gas exhaust passage 1,
A first catalyst layer 3 formed on the honeycomb carrier 2 and a second catalyst layer 4 formed on the first catalyst layer 3 are provided. That is, in each hole 2a of the honeycomb carrier 2, the first catalyst layer 3 and the second catalyst layer 4 are formed in layers, and the exhaust gas passes through the hole 2a in the second catalyst layer 4. It is designed to flow while touching the surface of.
【００１６】上記第１触媒層３は、排気ガスの低温時に
ＮＯｘを浄化しかつＨＣと反応する貴金属を含む触媒か
らなり、上記ハニカム担体２上に、Ｐｔ，Ｒｈ，Ｐｄ，
Ｒｕ等の貴金属のうち１種類以上を含む高比表面積のγ
−アルミナがウオッシュコートされたものである。The first catalyst layer 3 is composed of a catalyst containing a noble metal that purifies NOx and reacts with HC at a low temperature of exhaust gas, and is formed on the honeycomb carrier 2 with Pt, Rh, Pd,
Γ with a high specific surface area containing one or more kinds of precious metals such as Ru
-Alumina is wash-coated.
【００１７】上記第２触媒層４は、排気ガスの高温時に
ＮＯｘを浄化するゼオライトからなり、上記第１触媒層
３上に、Ｃｕ，Ｃｏ，Ｎｉ等の遷移金属をイオン交換担
持してなるゼオライトがウオッシュコートされたもので
ある。The second catalyst layer 4 is made of zeolite that purifies NOx when the exhaust gas is at a high temperature, and the first catalyst layer 3 is made by carrying out ion exchange loading of transition metals such as Cu, Co and Ni. Is wash-coated.
【００１８】次に、上記排気ガス浄化用触媒Ａの作用効
果について説明する。この触媒Ａに排気ガスを通すと、
上層の第２触媒層４を通過した排気ガス中のＨＣが、下
層の第１触媒層３上で燃焼し、ハニカム担体２の温度が
高められる。そのため、アイドルアップ時や高速走行時
等、排気ガスの温度が低かったり、従来では担体の温度
が低くて浄化が不可能な運転条件であっても、上層の第
２触媒層４がＮＯｘを浄化可能な温度まで達し、排気ガ
ス中のＨＣ、ＣＯはもとよりＮＯｘを効率よく浄化する
ことができる。また、排気ガスが高温時には、第２触媒
層４によりＨＣ、ＣＯおよびＮＯｘが浄化される。以上
の結果、アイドルアップ時から高速運転時まで排気ガス
の広い温度域でＮＯｘの浄化率を高くし、様々な自動車
のエンジンに実用化させることができる。Next, the function and effect of the exhaust gas purifying catalyst A will be described. When exhaust gas is passed through this catalyst A,
HC in the exhaust gas that has passed through the upper second catalyst layer 4 burns on the lower first catalyst layer 3 and the temperature of the honeycomb carrier 2 is raised. Therefore, even when the exhaust gas temperature is low, such as when the engine is idling up or running at high speeds, or under the operating conditions where the temperature of the carrier is low and purification cannot be performed conventionally, the upper second catalyst layer 4 purifies NOx. When the temperature reaches a possible temperature, NOx as well as HC and CO in the exhaust gas can be efficiently purified. Further, when the exhaust gas has a high temperature, the second catalyst layer 4 purifies HC, CO and NOx. As a result, the NOx purification rate can be increased in a wide temperature range of exhaust gas from idle-up to high-speed operation, and can be put to practical use in various automobile engines.
【００１９】この場合、第１触媒層３がＨＣの燃焼を促
進させるためには、γ−アルミナが２５０ m2 ／ｇ以上
の高比表面積を有することが望ましく、また、排気ガス
を下層の第１触媒層３にまで到達させるためには、上層
の第２触媒層４が厚すぎない方が良い。In this case, in order for the first catalyst layer 3 to promote the combustion of HC, it is desirable that γ-alumina has a high specific surface area of 250 m 2 / g or more. In order to reach the first catalyst layer 3, it is better that the upper second catalyst layer 4 is not too thick.
【００２０】さらに、第１触媒層３に含まれる貴金属は
高分散されていることが望ましい。また、ＨＣの燃焼を
進めすぎる貴金属は、上層の第２触媒層４での反応に用
いられるＨＣまで奪うので好ましくなく、逆に、ＨＣの
燃焼をあまり進めない貴金属は、上層の第２触媒層４を
通過した排気ガスのみでは燃焼を起こしにくい。したが
って、第１触媒層３に含まれる貴金属としては、Ｒｈ系
およびＰｔ系が望ましい。Further, it is desirable that the noble metal contained in the first catalyst layer 3 be highly dispersed. In addition, noble metal that advances combustion of HC too much robs HC used for reaction in the upper second catalyst layer 4, which is not preferable, and conversely, noble metal that does not advance combustion of HC too much is used as the upper second catalyst layer. Combustion is unlikely to occur with only the exhaust gas passing through No. 4. Therefore, the noble metal contained in the first catalyst layer 3 is preferably Rh-based or Pt-based.
【００２１】以下、上記排気ガス浄化用触媒Ａの具体例
を比較例とともに列挙し、かつその効果を述べる。Specific examples of the exhaust gas purifying catalyst A will be listed below along with comparative examples, and the effects thereof will be described.
【００２２】具体例１〜２および比較例１〜２ ４重量％のＲｈを均一に分散させた比表面積３２０ m2
／ｇのγ−アルミナにバインダーとして水和アルミナを
少量加えたものを、テストピース形状のコーディライト
製ハニカムにウオッシュコートした後、５００℃で約２
時間焼成した。この時、担体に対するウオッシュコート
量は約１０重量％とした。こうして得られた担体に対し
て、Ｓｉ／Ａｌ比が３０の酢酸銅を用いて約１３０％で
Ｃｕイオン交換したＺＳＭ−５（ゼオライトの１種）に
バインダーとして水和アルミナを少量加えたものを、ウ
オッシュコートした後、５００℃で約２時間焼成した。Specific Examples 1-2 and Comparative Examples 1-2 Specific surface area of 320 m 2 in which 4% by weight of Rh is uniformly dispersed.
/ G of γ-alumina with a small amount of hydrated alumina added as a binder was wash-coated on a test piece-shaped honeycomb made of cordierite, and then at about 500 ° C for about 2
Burned for hours. At this time, the amount of washcoat with respect to the carrier was set to about 10% by weight. To the carrier thus obtained, a small amount of hydrated alumina was added as a binder to ZSM-5 (a kind of zeolite) which was Cu ion-exchanged at about 130% with copper acetate having a Si / Al ratio of 30. After washcoating, it was baked at 500 ° C. for about 2 hours.
【００２３】こうして得られたテストピースを固定床流
通反応評価装置に設定し、実車の模擬ガス条件で排気ガ
スの浄化特性を評価した。評価テストは、ＮＯが２００
０ppm と、ＨＣが６０００ppm ・Ｃと、Ｏ２が８％と、
ＣＯ２が１０％と、ＣＯが０．２％と、Ｈ２が６５０pp
mとからなる混合ガスを、ＳＶ（空間速度）２５０００h
r-1で流すことにより行った。テスト中、バインダーの
パウダーが飛散しないようにした。その結果、図３に示
すように、テストピースａは、Ｃｕイオン交換したＺＳ
Ｍ−５のみからなる触媒層に混合ガスを流す場合ｂ（比
較例１）に比べ、ＮＯｘに反応する活性温度域が大幅に
低温側へ広がるとともに、４重量％のＲｈを含むγ−ア
ルミナのみからなる触媒層へ混合ガスを流す場合ｃ（比
較例２）に比べ、ＮＯｘ浄化率が４０％以上向上し、優
れたＮＯｘ浄化特性が得られた。The test piece thus obtained was set in a fixed bed flow reaction evaluation apparatus, and exhaust gas purification characteristics were evaluated under simulated gas conditions of an actual vehicle. The evaluation test is NO 200
0ppm, HC 6000ppm, C, O 2 8%,
CO 2 10%, CO 0.2%, H 2 650 pp
The mixed gas consisting of m and SV (space velocity) 25000h
It was carried out by flowing at r -1 . During the test, the binder powder was prevented from scattering. As a result, as shown in FIG. 3, the test piece a was Cu ion-exchanged ZS.
Compared to the case of b (Comparative Example 1) in which a mixed gas is flowed through a catalyst layer composed of only M-5, the active temperature range that reacts with NOx is greatly expanded to the low temperature side, and only γ-alumina containing 4% by weight of Rh is used. The NOx purification rate was improved by 40% or more, and excellent NOx purification characteristics were obtained, as compared with the case c (Comparative Example 2) in which the mixed gas was flowed to the catalyst layer made of.
【００２４】また、ＨＣ濃度を１００００ppm ・Ｃに変
え、それ以外を上記と同じ条件で評価テストをしたとこ
ろ、図４のｄに示すように、上記テストピースａに比
べ、ＮＯｘに反応する活性温度域がさらに低温側へ広が
るとともに、ＮＯｘ浄化率もさらに向上した。Further, when the HC concentration was changed to 10000 ppm · C and the other conditions were evaluated under the same conditions as above, as shown in FIG. 4d, as compared with the test piece a, the active temperature which reacts with NOx was higher. The range expanded to lower temperatures, and the NOx purification rate also improved.
【００２５】具体例３〜８ 具体例１と同じテスト条件で、材料の組み合わせと量と
を様々に変えて上記固定床流通反応評価装置によるテス
トを行った。その結果を表１に示す。具体例３〜７につ
いては、ＮＯｘ浄化率および活性温度域ともに良好な結
果を得た。具体例８については、Ｃｕイオン交換ゼオラ
イトの量が相対的に少なく、浄化開始温度は低温側へ移
動したが、高温域でのＮＯｘ浄化性能があまり充分では
なかった。また、具体例３の如く、第１触媒層をＰｔを
含むγ−アルミナで構成したところ、浄化開始温度はＣ
ｕイオン交換ゼオライトのみの場合に比べて６０℃近く
低くなり、燃焼特性が優れ、活性ピーク時に高いＮＯｘ
浄化率が得られた。しかしながら、Ｐｔの添加量が多す
ぎると、ＨＣの燃焼のみが進行する場合があった。第１
触媒層をＰｄを含むγ−アルミナで構成した場合、さら
にＨＣの燃焼を進行させる傾向があった。Specific Examples 3 to 8 Under the same test conditions as in Specific Example 1, various combinations of materials and various amounts of materials were used to perform the tests by the above fixed bed flow reaction evaluation apparatus. The results are shown in Table 1. For the specific examples 3 to 7, good results were obtained for both the NOx purification rate and the active temperature range. In Example 8, the amount of Cu ion-exchanged zeolite was relatively small and the purification start temperature moved to the low temperature side, but the NOx purification performance in the high temperature region was not sufficient. When the first catalyst layer is composed of γ-alumina containing Pt as in Example 3, the purification start temperature is C
Compared to the case of u ion-exchanged zeolite alone, the temperature is lower by about 60 ° C, the combustion characteristics are excellent, and NOx is high at the activity peak.
A purification rate was obtained. However, if the amount of Pt added is too large, only the combustion of HC may proceed. First
When the catalyst layer was composed of γ-alumina containing Pd, there was a tendency to further promote the combustion of HC.
【００２６】比較例３〜６ 具体例１と同じテスト条件で、触媒層を１層のみとして
材料の種類を変え、上記固定床流通反応評価装置による
テストを行った。その結果を表１に示す。比較例１につ
いては、ＨＣの燃焼が良く進み、浄化開始温度は低かっ
たが、ＮＯｘ浄化率は極めて低かった。また、比較例４
〜６については、いずれも浄化開始温度は高く、ＮＯｘ
浄化率も極めて低かった。Comparative Examples 3 to 6 Under the same test conditions as in Concrete Example 1, the catalyst bed was changed to one layer, the kind of material was changed, and the test was carried out by the above fixed bed flow reaction evaluation apparatus. The results are shown in Table 1. In Comparative Example 1, the combustion of HC proceeded well and the purification start temperature was low, but the NOx purification rate was extremely low. In addition, Comparative Example 4
For Nos. 6 to 6, the purification start temperature was high, and NOx
The purification rate was also extremely low.
【００２７】比較例７〜８ 具体例１と同じテスト条件で、材料の組み合わせと割合
とを様々に変えて上記固定床流通反応評価装置によるテ
ストを行った。その結果を表１に示す。いずれも、広い
温度域で高いＮＯｘ浄化率を得ることはできなかった。
比較例８の場合、第１触媒層にＣｕイオン交換したＺＳ
Ｍ−５を使用し、その上層にＰｔを含む高比表面積のγ
−アルミナで構成したもので、浄化開始温度は低かった
が、その後ＨＣの燃焼が優先的に進み、ＮＯｘ浄化率は
Ｃｕイオン交換ゼオライトのみの場合よりも大きく低下
した。Comparative Examples 7 to 8 Under the same test conditions as in Concrete Example 1, various combinations of materials and different ratios were used to carry out tests using the fixed bed flow reaction evaluation apparatus. The results are shown in Table 1. In all cases, it was not possible to obtain a high NOx purification rate in a wide temperature range.
In the case of Comparative Example 8, Cu ion-exchanged ZS was used for the first catalyst layer.
M-5 is used, and γ having a high specific surface area containing Pt in the upper layer is used.
-Although it was made of alumina, the purification start temperature was low, but then the combustion of HC proceeded preferentially, and the NOx purification rate was greatly reduced as compared with the case of Cu ion-exchanged zeolite alone.
【００２８】なお、図示はしないが、第１触媒層を金属
活性種を担持したアルミナで構成し、第２触媒層をＣｕ
イオン交換ゼオライトで構成した場合、第１触媒層の活
性温度が第２触媒層の活性温度と同じであるか、もしく
はより高いため、良好なＮＯｘ浄化性能が得られなかっ
た。Although not shown, the first catalyst layer is made of alumina carrying metal active species, and the second catalyst layer is made of Cu.
In the case of using ion-exchanged zeolite, the activation temperature of the first catalyst layer is the same as or higher than the activation temperature of the second catalyst layer, so that good NOx purification performance was not obtained.
【００２９】[0029]
【表１】 [Table 1]
【００３０】図５および図６は、本発明の第２実施例に
係る排気ガス浄化用触媒を示す。この排気ガス浄化用触
媒Ｂは、第１実施例と同様、排気ガスの排気路１の途中
に設けられており、６はハニカム担体５上に形成された
第１触媒層、７はこの第１触媒層６の上層に形成された
第２触媒層であり、上記ハニカム担体５の各孔５ａ内に
おいて、上記第１触媒層６と上記第２触媒層７とが層状
に形成されている。排気ガスは、各孔５ａ内を第２触媒
層７の表面に接しながら流れるようになっている。5 and 6 show an exhaust gas purifying catalyst according to the second embodiment of the present invention. The exhaust gas purifying catalyst B is provided in the middle of the exhaust gas exhaust passage 1 as in the first embodiment, 6 is the first catalyst layer formed on the honeycomb carrier 5, and 7 is the first catalyst layer. It is a second catalyst layer formed on the upper layer of the catalyst layer 6, and the first catalyst layer 6 and the second catalyst layer 7 are formed in layers in each hole 5a of the honeycomb carrier 5. The exhaust gas flows in each hole 5a while being in contact with the surface of the second catalyst layer 7.
【００３１】上記第１触媒層６は、上記ハニカム担体５
上に、Ｐｔ，Ｒｈ等の貴金属をイオン交換担持してなる
ゼオライトがウオッシュコートされたものであり、排気
ガスの低温域（３００℃前後）でＮＯｘ浄化率のピーク
を示す。The first catalyst layer 6 is the honeycomb carrier 5
The zeolite coated with ion-exchanged noble metals such as Pt and Rh is wash-coated on the top, and shows a peak of NOx purification rate in a low temperature region of exhaust gas (around 300 ° C.).
【００３２】上記第２触媒層７は、上記第１触媒層６上
に、Ｃｕをイオン交換担持してなるＣｕイオン交換ゼオ
ライトがウオッシュコートされたものであり、排気ガス
の高温域（４００℃付近）でＮＯｘを浄化する性能を有
する。The second catalyst layer 7 is formed by wash-coating Cu ion-exchanged zeolite having Cu ion-exchanged thereon on the first catalyst layer 6, and is used in a high temperature region of the exhaust gas (around 400 ° C.). ) Has the ability to purify NOx.
【００３３】そして、上記排気ガス浄化用触媒Ｂに排気
ガスを通すと、第１実施例の場合と同様に、上層の第２
触媒層７を通過した排気ガス中のＨＣが、下層の第１触
媒層６上で燃焼し、ハニカム担体５の温度が高められ
る。そのため、排気ガスが低温時であっても、上層の第
２触媒層７がＮＯｘを浄化可能な温度に到達し、排気ガ
ス中のＮＯｘを効率よく浄化することができる。また、
排気ガスが高温時には、第２触媒層４によりＮＯｘが浄
化される。以上の結果、アイドルアップ時から高速運転
時まで排気ガスの広い温度域でＮＯｘの浄化率を高く
し、様々な自動車のエンジンに実用化させることができ
る。Then, when the exhaust gas is passed through the exhaust gas purifying catalyst B, as in the case of the first embodiment, the second upper layer is used.
HC in the exhaust gas that has passed through the catalyst layer 7 burns on the lower first catalyst layer 6 and the temperature of the honeycomb carrier 5 is increased. Therefore, even when the exhaust gas is at a low temperature, the upper second catalyst layer 7 reaches a temperature at which NOx can be purified, and NOx in the exhaust gas can be efficiently purified. Also,
When the exhaust gas has a high temperature, the second catalyst layer 4 purifies NOx. As a result, the NOx purification rate can be increased in a wide temperature range of exhaust gas from idle-up to high-speed operation, and can be put to practical use in various automobile engines.
【００３４】上記排気ガス浄化用触媒Ｂは、次のように
して製造する。まず、ＺＳＭ−５またはモルデナイトを
用意し、これを湿式イオン交換法によりイオン交換率１
２０〜１４０％でＰｔおよびＲｈとイオン交換を行い、
その後、これにバインダーとして水和アルミナを加えて
水でスラリーとしたものを、ハニカムにウオッシュコー
トし、乾燥させた後、焼成する。一方、あらかじめＣｕ
イオン交換を行ったＺＳＭ−５またはモルデナイトにバ
インダーとして水和アルミナを加え、以下、上記と同じ
要領で製造する。The exhaust gas purifying catalyst B is manufactured as follows. First, ZSM-5 or mordenite is prepared, and the ion exchange rate of the ZSM-5 or mordenite is set to 1 by the wet ion exchange method.
Ion exchange with Pt and Rh at 20-140%,
Then, hydrated alumina as a binder is added to this, and a slurry made of water is wash-coated on the honeycomb, dried, and then fired. On the other hand, Cu
Hydrated alumina is added as a binder to ion-exchanged ZSM-5 or mordenite, and the same procedure as above is followed.
【００３５】図７は、上記排気ガス浄化用触媒Ｂに対し
てそのＮＯｘ浄化特性を評価した結果を示す。この評価
テストに当たり、第２触媒層のＣｕイオン交換ゼオライ
トのみを触媒として用いた場合の排気ガス浄化率を図８
に示し、第１触媒層のＰｔ−Ｒｈイオン交換ゼオライト
のみを触媒として用いた場合の排気ガス浄化率を図９に
示して、それぞれ比較例とした。FIG. 7 shows the results of evaluation of the NOx purification characteristics of the exhaust gas purification catalyst B. In this evaluation test, the exhaust gas purification rate when only the Cu ion-exchanged zeolite of the second catalyst layer was used as a catalyst is shown in FIG.
Fig. 9 shows the exhaust gas purification rate when only the Pt-Rh ion-exchanged zeolite of the first catalyst layer was used as a catalyst, and shown in Fig. 9 as comparative examples.
【００３６】上記テストは、ＮＯｘが２１００ppm 、Ｈ
Ｃが１４００ppm ・Ｃ、Ｏ２が７．５％、ＣＯが０．２
％、ＣＯ２が１０％およびＮ２バランスとで組成したガ
スを、ＳＶ（空間速度）２５０００hr-1で流すことによ
り行った。In the above test, NOx is 2100 ppm, H
C is 1400ppm-C, O 2 is 7.5%, CO is 0.2
%, CO 2 10%, and N 2 balance were used to flow at a SV (space velocity) of 25000 hr −1 .
【００３７】テストの結果、図７に示すように、３００
℃前から６００℃付近までの広い温度域でＮＯｘを浄化
することができた。As a result of the test, as shown in FIG.
It was possible to purify NOx in a wide temperature range from ℃ before to around 600 ℃.
【００３８】なお、Ｃｕイオン交換ＺＳＭ−５のみを触
媒として用いた場合は、図８に示すように、ＨＣの燃焼
（浄化反応）が始まり、その浄化率が高まるのと比例し
て、ＮＯｘ浄化率も向上し、４００℃付近でピークを迎
えた。ところが、その温度域より低温側ではＮＯｘ浄化
率は低かった。また、ＨＣおよびＣＯについては高い浄
化性能を示した。一方、Ｐｔ−Ｒｈイオン交換ＺＳＭ−
５のみを触媒として用いた場合は、図９に示すように、
ＮＯｘ浄化性能を発現させる温度域は、約２７０℃〜約
３３０℃付近の低温域であり、それ以上の温度域ではＮ
Ｏｘ浄化性能が極めて悪かった。また、ＨＣおよびＣＯ
については広い温度域で高い浄化性能を示した。When only Cu ion-exchange ZSM-5 is used as a catalyst, as shown in FIG. 8, combustion of HC (purification reaction) begins and NOx purification increases in proportion to the increase of the purification rate. The rate also improved and reached a peak near 400 ° C. However, the NOx purification rate was low at a temperature lower than that temperature range. Further, it showed high purification performance for HC and CO. On the other hand, Pt-Rh ion exchange ZSM-
When only 5 is used as a catalyst, as shown in FIG.
The temperature range in which the NOx purification performance is exhibited is a low temperature range of about 270 ° C. to about 330 ° C.
The Ox purification performance was extremely poor. Also, HC and CO
As for, the high purification performance was exhibited in a wide temperature range.
【００３９】上記第２実施例では、ハニカム担体５上
に、貴金属をイオン交換担持してなるゼオライトをウオ
ッシュコートして第１触媒層６とし、この第１触媒層６
の上層にＣｕイオン交換ゼオライトをウオッシュコート
して第２触媒層７とする構成であったが、これに限られ
るものではなく、排気路１の上流側にＣｕイオン交換ゼ
オライトを配置し、その下流側に貴金属をイオン交換担
持してなるゼオライトを配置するよう構成しても良い。In the second embodiment, the first catalyst layer 6 is wash-coated on the honeycomb carrier 5 with zeolite formed by carrying an ion exchange of a noble metal, to form the first catalyst layer 6.
The upper layer of the above was wash-coated with Cu ion-exchanged zeolite to form the second catalyst layer 7. However, the present invention is not limited to this, and the Cu ion-exchanged zeolite is arranged on the upstream side of the exhaust passage 1 and the downstream side thereof. You may comprise so that the zeolite which carries the ion exchange of the noble metal may be arrange | positioned at the side.
【００４０】図１０および図１１は、本発明の第３実施
例に係る排気ガス浄化用触媒を示す。この排気ガス浄化
用触媒Ｃは、第１実施例と同様、排気ガスの排気路１の
途中に設けられており、９はハニカム担体８上に形成さ
れた第１触媒層、１０はこの第１触媒層９の上層に形成
された第２触媒層であり、上記ハニカム担体８の各孔８
ａ内において、上記第１触媒層９と上記第２触媒層１０
とが層状に形成されている。排気ガスは、各孔８ａ内を
第２触媒層１０の表面に接しながら流れるようになって
いる。10 and 11 show an exhaust gas purifying catalyst according to the third embodiment of the present invention. The exhaust gas purifying catalyst C is provided in the middle of the exhaust gas exhaust passage 1 as in the first embodiment, and 9 is the first catalyst layer formed on the honeycomb carrier 8 and 10 is the first catalyst layer. The second catalyst layer is formed on the catalyst layer 9 and each hole 8 of the honeycomb carrier 8 is formed.
In a, the first catalyst layer 9 and the second catalyst layer 10
And are formed in layers. The exhaust gas flows in each hole 8a while being in contact with the surface of the second catalyst layer 10.
【００４１】上記第１触媒層９は、上記ハニカム担体８
上に高比表面積のγ−アルミナがウオッシュコートされ
たものであり、排気ガスの高温側（５００℃付近）でＮ
Ｏｘ浄化率のピークを示す。The first catalyst layer 9 is the honeycomb carrier 8
Γ-alumina having a high specific surface area is wash-coated on the upper side, and N on the high temperature side of exhaust gas (around 500 ° C)
The peak of Ox purification rate is shown.
【００４２】上記第２触媒層１０は、上記第１触媒層９
上に、Ｃｕをイオン交換担持してなるＣｕイオン交換ゼ
オライトがウオッシュコートされたものであり、排気ガ
スの低温側（４００℃付近）でＮＯｘを浄化する性能を
有する。The second catalyst layer 10 is the first catalyst layer 9
A Cu ion-exchanged zeolite having Cu ion-exchanged thereon is wash-coated, and has a capability of purifying NOx on the low temperature side of exhaust gas (around 400 ° C.).
【００４３】そして、上記排気ガス浄化用触媒Ｃに排気
ガスを通すと、排気ガスの低温側では、上層の第２触媒
層１０がＮＯｘに対する浄化性能を発揮し、排気ガス中
のＮＯｘを効率よく浄化することができる。また、排気
ガスの高温側では、第１触媒層９によりＮＯｘが浄化さ
れる。以上の結果、排気ガスの広い温度域でＮＯｘの浄
化率を高くし、酸素過剰雰囲気下の自動車のエンジンに
実用化させることができる。When the exhaust gas is passed through the exhaust gas purifying catalyst C, the upper second catalyst layer 10 exerts the purifying performance for NOx on the low temperature side of the exhaust gas, and the NOx in the exhaust gas is efficiently emitted. Can be purified. Further, on the high temperature side of the exhaust gas, NOx is purified by the first catalyst layer 9. As a result, the NOx purification rate can be increased in a wide temperature range of the exhaust gas, and the NOx purification rate can be put to practical use in an automobile engine under an oxygen excess atmosphere.
【００４４】図１２は、上記排気ガス浄化用触媒Ｃに対
してそのＮＯｘ浄化特性ａをテストした結果を示す。こ
のテストに当たり、第２触媒層のＣｕイオン交換ゼオラ
イトのみを触媒として用いた場合ｂと、第１触媒層のγ
−アルミナのみを触媒として用いた場合ｃとを、比較例
とした。上記Ｃｕイオン交換ゼオライトを製造するにあ
たり、ＺＳＭ−５またはモルデナイトを用意し、これを
湿式イオン交換法によりイオン交換率１２０〜１４０％
でＣｕイオン交換を行い、その後、これにバインダーと
して水和アルミナ１０重量％を加えて水でスラリーとし
たものを、ハニカムにウオッシュコートし、１２０℃で
乾燥させた後、５００℃で焼成した。一方、γ−アルミ
ナとしては、比表面積３００ m2 ／ｇのものを用意し、
これにバインダーとして水和アルミナ１０重量％を加
え、以下、上記と同じ要領で製造した。FIG. 12 shows the results of testing the NOx purification characteristic a of the exhaust gas purification catalyst C. In this test, when only the Cu ion-exchanged zeolite in the second catalyst layer was used as a catalyst b, and in the first catalyst layer γ
A case where only alumina was used as a catalyst was used as a comparative example. In producing the Cu ion-exchanged zeolite, ZSM-5 or mordenite is prepared, and the ion exchange rate is 120 to 140% by a wet ion-exchange method.
Cu ion exchange was carried out, and thereafter, 10% by weight of hydrated alumina as a binder was added thereto to make a slurry with water, which was wash-coated on a honeycomb, dried at 120 ° C., and then fired at 500 ° C. On the other hand, γ-alumina having a specific surface area of 300 m 2 / g is prepared,
To this, 10% by weight of hydrated alumina was added as a binder, and the same procedure as above was followed.
【００４５】本実施例の排気ガス浄化用触媒Ｃは、次の
ようにして調整した。まず、ハニカムに上記と同じ方法
でγ−アルミナをウオッシュコートして、乾燥および焼
成を行った後、その上層に上記と同じ方法でＣｕイオン
交換ＺＳＭ−５をウオッシュコートして、乾燥および焼
成を行った。The exhaust gas purifying catalyst C of this example was prepared as follows. First, the honeycomb was wash-coated with γ-alumina by the same method as described above, dried and fired, and then the Cu ion-exchange ZSM-5 was wash-coated on the upper layer by the same method as described above, and dried and fired. went.
【００４６】テストの結果、Ｃｕイオン交換ＺＳＭ−５
（図１２のｂ）は、４００℃付近を浄化率のピークと
し、この温度域より高温側ではＮＯｘ浄化率は低かっ
た。一方、γ−アルミナ（図１２のｃ）は、５００℃付
近で浄化率のピークを示した。本実施例の排気ガス浄化
用触媒Ｃ（図１２のａ）は、個々の触媒の活性温度域よ
り広い温度域でＮＯｘ浄化特性を示した。As a result of the test, Cu ion exchange ZSM-5
In (b of FIG. 12), the peak of the purification rate is around 400 ° C., and the NOx purification rate was low on the higher temperature side than this temperature range. On the other hand, γ-alumina (c in FIG. 12) showed a peak of purification rate at around 500 ° C. The exhaust gas purifying catalyst C (a in FIG. 12) of the present example exhibited NOx purification characteristics in a temperature range wider than the activation temperature range of each catalyst.
【００４７】テスト条件は、担体として４００セルのハ
ニカムを使用し、ガスは、ＮＯが１４００ppm 、ＨＣが
２０００ppm ・Ｃ、Ｏ２が８％およびＮ２バランスとで
組成し、ＳＶ（空間速度）２５０００hr-1で流した。The test conditions were that a honeycomb of 400 cells was used as a carrier, and the gas was composed of NO of 1400 ppm, HC of 2000 ppm.C, O 2 of 8% and N 2 balance, and SV (space velocity) of 25000 hr. -1 shed.
【００４８】[0048]
【発明の効果】以上のように、本発明の排気ガス浄化用
触媒によれば、第２触媒層を通過した排気ガス中のＨＣ
が、第１触媒層の貴金属と反応して燃焼し、担体の温度
を高めるため、排気ガスの温度が低かったり、従来では
担体温度が低くなるような運転条件でも、第２触媒層が
ＮＯｘを浄化することが可能な活性温度まで到達し、低
温時の排気ガス中のＮＯｘを浄化することができる。ま
た、排気ガスが高温時には、第２触媒層によりＮＯｘを
浄化することができる。よって、アイドルアップ時から
高速運転時まで排気ガスの広い温度域でＮＯｘの浄化率
を高くすることができ、様々な自動車のエンジンに実用
化させることができる。As described above, according to the exhaust gas purifying catalyst of the present invention, the HC in the exhaust gas that has passed through the second catalyst layer is
However, since it reacts with the noble metal of the first catalyst layer and burns to raise the temperature of the carrier, the second catalyst layer produces NOx even under operating conditions where the temperature of the exhaust gas is low or the temperature of the carrier is conventionally low. The NOx in the exhaust gas at low temperature can be purified by reaching the active temperature at which purification is possible. Further, when the exhaust gas has a high temperature, NOx can be purified by the second catalyst layer. Therefore, the NOx purification rate can be increased in a wide temperature range of exhaust gas from idling up to high speed operation, and can be put to practical use in various automobile engines.
【図１】本発明の第１実施例を示す排気ガス浄化用触媒
の斜視図である。FIG. 1 is a perspective view of an exhaust gas purifying catalyst according to a first embodiment of the present invention.
【図２】同部分拡大図である。FIG. 2 is an enlarged view of the same portion.
【図３】第１実施例における排気ガス浄化用触媒の排気
ガスに対するＮＯｘ浄化率を示すグラフである。FIG. 3 is a graph showing the NOx purification rate for exhaust gas of the exhaust gas purification catalyst in the first embodiment.
【図４】同じく排気ガスの組成を変えた場合のＮＯｘ浄
化率を示すグラフである。FIG. 4 is a graph showing the NOx purification rate when the composition of exhaust gas is changed.
【図５】本発明の第２実施例を示す排気ガス浄化用触媒
の斜視図である。FIG. 5 is a perspective view of an exhaust gas purifying catalyst showing a second embodiment of the present invention.
【図６】同部分拡大図である。FIG. 6 is an enlarged view of the same portion.
【図７】第２実施例における排気ガス浄化用触媒の排気
ガスに対するＮＯｘ浄化率を示すグラフである。FIG. 7 is a graph showing the NOx purification rate with respect to exhaust gas of the exhaust gas purification catalyst in the second embodiment.
【図８】Ｃｕイオン交換ＺＳＭ−５の排気ガス低減率を
示すグラフである。FIG. 8 is a graph showing the exhaust gas reduction rate of Cu ion exchange ZSM-5.
【図９】Ｐｔ−Ｒｈイオン交換ＺＳＭ−５の排気ガス低
減率を示すグラフである。FIG. 9 is a graph showing an exhaust gas reduction rate of Pt-Rh ion exchange ZSM-5.
【図１０】第３実施例における排気ガス浄化用触媒の排
気ガスに対するＮＯｘ浄化率を示すグラフである。FIG. 10 is a graph showing the NOx purification rate with respect to exhaust gas of the exhaust gas purification catalyst in the third embodiment.
【図１１】本発明の第３実施例を示す排気ガス浄化用触
媒の斜視図である。FIG. 11 is a perspective view of an exhaust gas purifying catalyst showing a third embodiment of the present invention.
【図１２】同部分拡大図である。FIG. 12 is an enlarged view of the same portion.
１ 排気路 ２，５，８ ハニカム担体 ３，６，９ 第１触媒層 ４，７，１０ 第２触媒層 1 Exhaust Path 2, 5, 8 Honeycomb Carrier 3, 6, 9 First Catalyst Layer 4, 7, 10 Second Catalyst Layer
フロントページの続き (72)発明者 高見 明秀 広島県安芸郡府中町新地３番１号 マツダ 株式会社内 (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Front Page Continuation (72) Inventor Akihide Takami, 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor, Satoshi Ichikawa 3-1-1 Shinchu, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Corporation
Claims (3)
浄化用触媒であって、担体上に形成され排気ガスの低温
時にＮＯｘを浄化しかつＨＣと反応する貴金属を含む触
媒からなる第１触媒層と、この第１触媒層の上層に形成
され排気ガスの高温時にＮＯｘを浄化するゼオライトか
らなる第２触媒層とを備えたことを特徴とする排気ガス
浄化用触媒。1. A catalyst for purifying exhaust gas provided in an exhaust passage for exhaust gas, comprising a catalyst containing a noble metal which is formed on a carrier for purifying NOx and reacting with HC when purifying exhaust gas at a low temperature. An exhaust gas purifying catalyst comprising: a catalyst layer; and a second catalyst layer formed on the first catalyst layer, the second catalyst layer consisting of zeolite that purifies NOx when the exhaust gas has a high temperature.
γ−アルミナからなる請求項１記載の排気ガス浄化用触
媒。2. The exhaust gas purifying catalyst according to claim 1, wherein the first catalyst layer is composed of γ-alumina carrying a noble metal.
ゼオライトからなる請求項１記載の排気ガス浄化用触
媒。3. The exhaust gas purifying catalyst according to claim 1, wherein the first catalyst layer is made of a zeolite carrying a noble metal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3234669A JPH0568888A (en) | 1991-09-13 | 1991-09-13 | Waste gas cleaning catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3234669A JPH0568888A (en) | 1991-09-13 | 1991-09-13 | Waste gas cleaning catalyst |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0568888A true JPH0568888A (en) | 1993-03-23 |
Family
ID=16974618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3234669A Pending JPH0568888A (en) | 1991-09-13 | 1991-09-13 | Waste gas cleaning catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0568888A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06315635A (en) * | 1992-12-14 | 1994-11-15 | Sekiyu Sangyo Kasseika Center | Catalytic structure for nitrogen oxide catalytic reduction |
| US5427989A (en) * | 1993-03-11 | 1995-06-27 | Nissan Motor Co., Ltd. | Catalysts for the purification of exhaust gas |
| EP0935055A2 (en) | 1998-02-05 | 1999-08-11 | Nissan Motor Company, Limited | Device for purifying oxygen rich exhaust gas |
| US6066587A (en) * | 1996-09-26 | 2000-05-23 | Mazda Motor Corporation | Catalyst for purifying exhaust gas |
| JP2008279352A (en) * | 2007-05-10 | 2008-11-20 | Asahi Kasei Corp | Catalyst for removing nitrogen oxide discharged from lean burn automobile |
-
1991
- 1991-09-13 JP JP3234669A patent/JPH0568888A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06315635A (en) * | 1992-12-14 | 1994-11-15 | Sekiyu Sangyo Kasseika Center | Catalytic structure for nitrogen oxide catalytic reduction |
| US5427989A (en) * | 1993-03-11 | 1995-06-27 | Nissan Motor Co., Ltd. | Catalysts for the purification of exhaust gas |
| US6066587A (en) * | 1996-09-26 | 2000-05-23 | Mazda Motor Corporation | Catalyst for purifying exhaust gas |
| EP0935055A2 (en) | 1998-02-05 | 1999-08-11 | Nissan Motor Company, Limited | Device for purifying oxygen rich exhaust gas |
| JP2008279352A (en) * | 2007-05-10 | 2008-11-20 | Asahi Kasei Corp | Catalyst for removing nitrogen oxide discharged from lean burn automobile |
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