JPH05228342A - Purifier for exhaust gas - Google Patents
Purifier for exhaust gasInfo
- Publication number
- JPH05228342A JPH05228342A JP4032531A JP3253192A JPH05228342A JP H05228342 A JPH05228342 A JP H05228342A JP 4032531 A JP4032531 A JP 4032531A JP 3253192 A JP3253192 A JP 3253192A JP H05228342 A JPH05228342 A JP H05228342A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- catalyst
- nox
- impregnated
- purification
- 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
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Landscapes
- Exhaust Gas After Treatment (AREA)
- 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、内燃機関または外燃機
関の排気ガス中に含まれるＨＣ、ＣＯ、ＮＯｘ等の有害
ガスをＣＯ２、Ｈ２Ｏ、Ｎ２等の無害ガスに浄化する排
気ガス浄化装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention purifies harmful gases such as HC, CO and NOx contained in exhaust gas of an internal combustion engine or an external combustion engine into harmless gases such as CO 2 , H 2 O and N 2. The present invention relates to an exhaust gas purification device.
【０００２】[0002]
【従来の技術】一般に、ガソリンエンジンの排気ガスを
浄化する触媒としては、貴金属を担持した三元触媒が使
用されている。しかしながら、ディーゼルエンジン、燃
料消費率の低い希薄燃焼式（リーンバーン）エンジン等
の排気ガスのように、酸素を多く含む排気ガスに対して
は、三元触媒は全くＮＯｘを浄化する性能を持たない。2. Description of the Related Art Generally, a three-way catalyst carrying a noble metal is used as a catalyst for purifying exhaust gas from a gasoline engine. However, the three-way catalyst has no ability to purify NOx for exhaust gas containing a large amount of oxygen such as exhaust gas of a diesel engine, a lean burn engine with a low fuel consumption rate, etc. ..
【０００３】そこで、酸素を多く含む排気ガスに対して
ＮＯｘ浄化性能を持つＮＯｘ浄化用触媒として、ゼオラ
イトに遷移金属をイオン交換してなるイオン交換ゼオラ
イト、γ−Ａｌ２Ｏ３、ペロブスカイト等が開発され、
これらの触媒が排気ガスの排気路に配設された排気ガス
浄化装置は既に公知になっている。Therefore, as a NOx purification catalyst having NOx purification performance for exhaust gas containing a large amount of oxygen, ion-exchanged zeolite formed by ion exchange of transition metal with zeolite, γ-Al 2 O 3 , perovskite, etc. have been developed. Was
An exhaust gas purifying device in which these catalysts are arranged in the exhaust gas exhaust passage has already been known.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上記従
来の排気ガス浄化装置では、いずれのＮＯｘ浄化用触媒
もＮＯｘを浄化する速度があまり大きくないため、実際
に走行する自動車（いわゆる実車）の排気ガス等、流速
が速くしかも大量に排出される排気ガスを処理するのは
困難であるという問題がある。However, in the above-mentioned conventional exhaust gas purifying apparatus, since the NOx purifying catalyst does not have a very high NOx purifying speed, the exhaust gas of an actually running automobile (so-called actual vehicle) However, there is a problem that it is difficult to treat exhaust gas that has a high flow velocity and is discharged in large amounts.
【０００５】ところで、上記いずれのＮＯｘ浄化用触媒
も、排気ガス中にＮＯｘとともにＨＣが共存するときに
のみＮＯｘ浄化性能を発揮し、排気ガス中のＨＣ濃度が
高いほど排気ガス低温時の浄化反応が進行することが分
かっている。したがって、排気ガスに対するＮＯｘ浄化
性能を高めるためには、排気ガス中のＨＣ濃度を高める
ことが重要である。By the way, any of the above NOx purification catalysts exerts NOx purification performance only when HC coexists with NOx in the exhaust gas, and the higher the HC concentration in the exhaust gas, the lower the exhaust gas purification reaction. Is known to progress. Therefore, it is important to increase the HC concentration in the exhaust gas in order to improve the NOx purification performance for the exhaust gas.
【０００６】また、上記ＮＯｘ浄化用触媒は、排気ガス
中のＮＯｘ成分のうち、ＮＯよりも構造として不安定な
ＮＯ２の方に対して還元反応を促進させる性質を有して
いる。すなわち、図３は、排気ガス中のＮＯｘ成分に占
めるＮＯの割合とＮＯｘ全体の浄化率との関係をテスト
した際の結果を示す。このテストは、実車の排気路と同
じ条件の排気ガス流通装置を用いて、この装置に、ゼオ
ライトの１種であるＺＳＭ−５に銅をイオン交換担持し
たＮＯｘ浄化用触媒（Ｃｕイオン担持量２ｇ）を配設
し、この触媒に対して実際の排気ガスと同じ組成のテス
トガスを流したものである。テストガスの組成は、ＮＯ
ｘが２０００ppm 、ＨＣが６０００ppm ・Ｃ、Ｈ２が６
５０ppm 、Ｏ２が８％、ＣＯ２が１０％、ＣＯが０．２
％であり、テストガスの流速は、空間速度ＳＶ＝２５０
００ｈ-1であった。上記テストの結果、排気ガス中のＮ
Ｏｘ成分に占めるＮＯの割合が低いほど、換言すれば、
ＮＯ２の割合が高いほどＮＯｘ浄化率が高くなることが
分かった。The NOx purification catalyst has a property of accelerating the reduction reaction of NO 2 which is structurally more unstable than NO among NOx components in the exhaust gas. That is, FIG. 3 shows the results of testing the relationship between the proportion of NO in the NOx component in the exhaust gas and the purification rate of NOx as a whole. In this test, an exhaust gas flow device under the same conditions as the exhaust path of the actual vehicle was used, and in this device, a NOx purification catalyst (Cu ion loading amount 2 g of Cu ion-loaded ZSM-5, which is one of the zeolites, was used. ) Is provided, and a test gas having the same composition as the actual exhaust gas is caused to flow through the catalyst. The composition of the test gas is NO
x is 2000ppm, HC is 6000ppm. ・ C and H 2 are 6
50ppm, O 2 8%, CO 2 10%, CO 0.2
%, And the flow velocity of the test gas is space velocity SV = 250
It was 00h -1 . As a result of the above test, N in exhaust gas
The lower the proportion of NO in the Ox component, in other words,
It was found that the higher the proportion of NO 2, the higher the NOx purification rate.
【０００７】したがって、排気ガスに対するＮＯｘ浄化
率を高めるためには、排気ガス中のＮＯｘ成分に占める
ＮＯ２の割合を高くすることも重要である。Therefore, in order to increase the NOx purification rate for exhaust gas, it is important to increase the proportion of NO 2 in the NOx component in the exhaust gas.
【０００８】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、ＮＯｘ浄化性能に優
れた排気ガス浄化装置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, and an object thereof is to provide an exhaust gas purifying apparatus having excellent NOx purifying performance.
【０００９】[0009]
【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、ＨＣを酸化させにくい性質を有しかつＮＯを酸化さ
せる貴金属含浸触媒と、上記排気路の上記貴金属含浸触
媒より下流側に設けられ、ＮＯｘを還元するＮＯｘ浄化
用触媒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 provided with an exhaust gas exhaust passage, is impregnated with a precious metal which has a property of hardly oxidizing HC and oxidizes NO. A catalyst and a NOx purification catalyst that is provided downstream of the precious metal-impregnated catalyst in the exhaust passage and that reduces NOx are provided.
【００１０】請求項２記載の発明は、上記請求項１記載
の発明において、貴金属含浸触媒を、Ａ型ゼオライトに
白金を含浸させてなるＰｔ含浸Ａ型ゼオライトとする構
成とするものである。According to a second aspect of the invention, in the invention of the first aspect, the noble metal-impregnated catalyst is a Pt-impregnated A-type zeolite obtained by impregnating A-type zeolite with platinum.
【００１１】請求項３記載の発明は、上記請求項１また
は２記載の発明において、排気路の上記ＮＯｘ浄化用触
媒より下流側に、三元触媒を配設する構成とするもので
ある。According to a third aspect of the present invention, in the first or second aspect of the invention, a three-way catalyst is arranged downstream of the NOx purification catalyst in the exhaust passage.
【００１２】[0012]
【作用】上記の構成により、請求項１記載の発明では、
排気路の上流側に位置する貴金属含浸触媒により、排気
ガス中のＮＯｘのうち、比較的安定したＮＯが酸化され
てより反応性に優れたＮＯ２に多量に転化されるととも
に、ＨＣがあまり燃焼されずに下流側のＮＯｘ浄化用触
媒へ流れる。ＮＯｘ浄化用触媒は、ＨＣの働きでＮＯｘ
還元反応を促進させ、上記多量のＮＯ２に対して積極的
に還元反応を起こし、ＮＯ２を浄化する。With the above construction, in the invention according to claim 1,
The noble metal-impregnated catalyst located on the upstream side of the exhaust passage oxidizes relatively stable NO out of NOx in the exhaust gas and converts it into a more reactive NO 2 in a large amount, and HC burns too much. Instead, it flows to the NOx purification catalyst on the downstream side. The NOx purification catalyst functions as NOx by the action of HC.
The reduction reaction is promoted, the reduction reaction is positively caused to the large amount of NO 2 , and the NO 2 is purified.
【００１３】特に、請求項３記載の発明では、ＮＯｘ浄
化用触媒によりＮＯｘが浄化された排気ガスは、さらに
下流側の三元触媒へ流れ、この三元触媒により排気ガス
中のＨＣおよびＣＯが浄化される。Particularly, in the third aspect of the invention, the exhaust gas in which NOx is purified by the NOx purification catalyst flows to the downstream three-way catalyst, and HC and CO in the exhaust gas are discharged by this three-way catalyst. Purified.
【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は本発明の第１実施例に係る排気ガス
浄化装置Ａを示す。この排気ガス浄化装置Ａは、エンジ
ン１から排出された排気ガスが流れる排気路２に設けら
れており、ＨＣを酸化させにくい性質を有しかつＮＯを
酸化させる貴金属含浸触媒３と、上記排気路２の上記貴
金属含浸触媒３より下流側に設けられ、ＮＯｘを還元す
るＮＯｘ浄化用触媒４とを備えている。FIG. 1 shows an exhaust gas purifying apparatus A according to a first embodiment of the present invention. The exhaust gas purifying apparatus A is provided in the exhaust passage 2 through which the exhaust gas discharged from the engine 1 flows, and has a precious metal impregnated catalyst 3 that has a property of hardly oxidizing HC and oxidizes NO, and the exhaust passage. 2 is provided on the downstream side of the precious metal-impregnated catalyst 3 and is provided with a NOx purification catalyst 4 that reduces NOx.
【００１６】上記貴金属含浸触媒３は、Ａ型ゼオライト
に白金を含浸させてなるＰｔ含浸Ａ型ゼオライトであ
り、上記ＮＯｘ浄化用触媒４は、ゼオライトの１種であ
るＺＳＭ−５に銅をイオン交換担持してなるＣｕイオン
交換ＺＳＭ−５である。The precious metal-impregnated catalyst 3 is a Pt-impregnated A-type zeolite obtained by impregnating an A-type zeolite with platinum. The NOx purification catalyst 4 is ion-exchanged with copper for ZSM-5, which is one type of zeolite. It is Cu ion exchange ZSM-5 formed by supporting.
【００１７】なお、上記ＮＯｘ浄化用触媒の浄化性能を
促進させるためには、排気ガス中のＮＯｘ濃度（ppm ）
に対してＨＣ濃度（ppm ・Ｃ）が１．０倍以上であるこ
とが望ましい。In order to promote the purification performance of the NOx purification catalyst, the NOx concentration (ppm) in the exhaust gas
However, it is desirable that the HC concentration (ppm C) be 1.0 times or more.
【００１８】次に、上記実施例の作用について説明する
と、エンジン１から排出された排気ガスは、排気路２の
上流側に位置する貴金属含浸触媒３により、排気ガス中
のＮＯｘ成分のうち、比較的安定したＮＯが酸化されて
より反応性に優れたＮＯ２に多量に転化されるととも
に、ＨＣがあまり燃焼されずに下流側のＮＯｘ浄化用触
媒４へ流れる。そして、上記多量のＮＯ２は、ＨＣの働
きでＮＯｘ還元反応を促進させたＮＯｘ浄化用触媒４に
より積極的に還元反応を起こして浄化される。このよう
に、排気ガス中のＮＯｘ成分のうち反応性に優れたＮＯ
２の割合が増え、このＮＯ２が活発な還元反応を起こし
て浄化されるため、これまで浄化されにくかった排気ガ
ス中のＮＯ成分をも積極的に除去できるので、ＮＯｘ全
体としての浄化率を向上させることができる。Explaining the operation of the above embodiment, the exhaust gas discharged from the engine 1 is compared with the NOx components in the exhaust gas by the noble metal-impregnated catalyst 3 located upstream of the exhaust passage 2. The stable NO is oxidized and converted to a large amount into more reactive NO 2 , and HC is not burned so much and flows to the NOx purification catalyst 4 on the downstream side. The large amount of NO 2 is purified by positively causing a reduction reaction by the NOx purification catalyst 4 which promotes the NOx reduction reaction by the action of HC. In this way, of the NOx components in the exhaust gas, the highly reactive NOx
The ratio of 2 increases, and this NO 2 undergoes an active reduction reaction for purification, so that the NO component in the exhaust gas, which has been difficult to purify up to now, can also be actively removed, so the overall purification rate of NOx can be improved. Can be improved.
【００１９】図２は、本発明の第２実施例に係る排気ガ
ス浄化装置Ｂを示す。この排気ガス浄化装置Ｂは、上記
第１実施例と同様、排気ガスの排気路２に設けられてお
り、貴金属含浸触媒３と、この貴金属含浸触媒３より下
流側に設けられたＮＯｘ浄化用触媒４とを備えている。
さらに、このＮＯｘ浄化用触媒４より下流側の排気路２
には、三元触媒５が配設されている。FIG. 2 shows an exhaust gas purifying apparatus B according to the second embodiment of the present invention. This exhaust gas purification apparatus B is provided in the exhaust gas exhaust passage 2 as in the first embodiment, and is provided with a precious metal impregnated catalyst 3 and a NOx purification catalyst provided downstream of the precious metal impregnated catalyst 3. 4 and.
Further, the exhaust passage 2 downstream of the NOx purification catalyst 4
A three-way catalyst 5 is arranged in the.
【００２０】上記貴金属含浸触媒３はＰｔ含浸Ａ型ゼオ
ライトであり、上記ＮＯｘ浄化用触媒４はＣｕイオン交
換ＺＳＭ−５である。The noble metal-impregnated catalyst 3 is Pt-impregnated A-type zeolite, and the NOx purification catalyst 4 is Cu ion-exchange ZSM-5.
【００２１】上記三元触媒５は、排気ガス中のＨＣおよ
びＣＯの酸化を促進させて、Ｈ２ＯとＣＯ２の無害ガス
にして浄化する触媒であり、γ−アルミナ等の触媒材料
にＰｔおよびＲｈの貴金属種が担持されてなるものであ
る。The three-way catalyst 5 is a catalyst for promoting the oxidation of HC and CO in the exhaust gas to convert it into a harmless gas of H 2 O and CO 2 and purifying it. And a noble metal species of Rh are supported.
【００２２】上記第２実施例の作用について説明する
と、第１実施例と同様、排気ガスは、貴金属含浸触媒３
により、ＮＯｘ中のＮＯが反応性に優れたＮＯ２に多量
に転化されるとともに、多量のＨＣがＮＯｘ浄化用触媒
４へ流れる。そして、上記多量のＮＯ２は、ＨＣの働き
でＮＯｘ還元反応を促進させたＮＯｘ浄化用触媒４によ
り積極的に還元反応を起こして浄化される。したがっ
て、ＮＯｘ全体としての浄化率を向上させることができ
る。Explaining the operation of the second embodiment, as in the first embodiment, the exhaust gas is noble metal impregnated catalyst 3
As a result, a large amount of NO in NOx is converted into NO 2 having excellent reactivity, and a large amount of HC flows to the NOx purification catalyst 4. The large amount of NO 2 is purified by positively causing a reduction reaction by the NOx purification catalyst 4 which promotes the NOx reduction reaction by the action of HC. Therefore, the purification rate of NOx as a whole can be improved.
【００２３】また、ＮＯｘ浄化用触媒４によりＮＯｘが
浄化された排気ガスは、さらに下流側の三元触媒５へ流
れ、この三元触媒５により排気ガス中のＨＣおよびＣＯ
が浄化される。この結果、排気ガス中のすべての有害成
分を浄化することができる。The exhaust gas from which NOx has been purified by the NOx purification catalyst 4 further flows to the three-way catalyst 5 on the downstream side, and the three-way catalyst 5 causes HC and CO in the exhaust gas to flow.
Is purified. As a result, all harmful components in the exhaust gas can be purified.
【００２４】なお、上記第１および第２実施例では、貴
金属含浸触媒３として、Ｐｔ含浸Ａ型ゼオライトを使用
していたが、これに限られるものではなく、ゼオライト
やγ−アルミナ等の触媒材料にＰｔ，Ｐｄ，Ｒｈ，Ｉｒ
等の貴金属種のうちの１種以上を担持してなる触媒を使
用できる。Although Pt-impregnated A-type zeolite was used as the noble metal-impregnated catalyst 3 in the first and second examples, the present invention is not limited to this, and catalyst materials such as zeolite and γ-alumina are used. On Pt, Pd, Rh, Ir
It is possible to use a catalyst which carries one or more kinds of noble metal species such as
【００２５】また、上記第１および第２実施例では、Ｎ
Ｏｘ浄化用触媒４として、Ｃｕイオン交換ＺＳＭ−５を
使用していたが、これに限られるものではなく、様々な
ゼオライトや他の金属含有シリケートからなる触媒材料
に、Ｃｕ，Ｃｏ，Ｍｎ，Ｎｉ等の遷移金属のうちの１種
以上をイオン交換担持してなる触媒を使用しても良い。In the first and second embodiments described above, N
Cu ion-exchange ZSM-5 was used as the Ox purification catalyst 4, but the present invention is not limited to this, and Cu, Co, Mn, Ni can be used for catalyst materials composed of various zeolites and other metal-containing silicates. You may use the catalyst which carry | supported the ion exchange of 1 or more types of transition metals, such as.
【００２６】さらに、上記第２実施例では、三元触媒５
として、γ−アルミナ等の触媒材料にＰｔおよびＲｈの
貴金属種が担持されてなる触媒を使用していたが、これ
に限られるものではなく、触媒材料にＰｔ，Ｒｈ，Ｐ
ｄ，Ｉｒ等の貴金属種のうちの１種以上を担持してなる
触媒を使用しても良い。Further, in the second embodiment, the three way catalyst 5 is used.
As the catalyst, a catalyst in which a noble metal species of Pt and Rh are supported on a catalyst material such as γ-alumina is used, but the catalyst material is not limited to this, and Pt, Rh, P is used as the catalyst material.
You may use the catalyst which carry | supported 1 or more types of noble metal species, such as d and Ir.
【００２７】次に、上記第１実施例の排気ガス浄化装置
Ａをエンジンに接続して排気ガス中の有毒ガス成分に対
する浄化性能をテストし、その結果を表１に示す。表１
において、ａ、ｂ、ｃはそれぞれ図１中のａ点、ｂ点、
ｃ点における排気ガスの組成を示したものである。な
お、テストにあたり、回転数１８００rpm 、１．３リッ
トルのガソリンエンジンを使用し、空燃比が２１の排気
ガスを流した。また、貴金属含浸触媒のＰｔ担持量を担
体１．１リットル当たり１００ｇとし、ＮＯｘ浄化用触
媒のＣｕイオン担持量を担体１．１リットル当たり１０
０ｇとした。Next, the exhaust gas purifying apparatus A of the first embodiment was connected to an engine to test the purifying performance for poisonous gas components in the exhaust gas, and the results are shown in Table 1. Table 1
, A, b, and c are points a, b, and
It shows the composition of the exhaust gas at point c. In the test, a 1.3 liter gasoline engine with a rotation speed of 1800 rpm was used, and exhaust gas with an air-fuel ratio of 21 was passed. The amount of Pt supported on the noble metal impregnated catalyst was 100 g per 1.1 liter of the carrier, and the amount of Cu ions supported on the NOx purification catalyst was 10 per 1.1 liter of the carrier.
It was set to 0 g.
【００２８】[0028]
【表１】 表１から分かるように、貴金属含浸触媒３より上流の地
点ａで５５ppm であったＮＯ２は、貴金属含浸触媒３と
ＮＯｘ浄化用触媒４との中間地点ｂで１９０ppm に増加
している。一方、上記ａ点で４９４ppm あったＮＯは、
上記ｂ点ではほぼＮＯ２の増加量に相当する量を失い、
３５７ppm に減少している。そして、ＮＯｘ浄化用触媒
４を通過した後の地点ｃでは、ＮＯおよびＮＯ２を合わ
せたＮＯｘ量は、上記ａ点のＮＯｘ量に対して４９．５
％に減少している（ＮＯｘ浄化率５０．５％）。また、
ＨＣは、上記貴金属含浸触媒３ではあまり浄化されず、
上記ＮＯｘ浄化用触媒４へ達しているが、上記ｃ点で
は、上記ａ点に対して６６．１％が浄化されている。[Table 1] As can be seen from Table 1, NO 2 which was 55 ppm at the point a upstream of the precious metal-impregnated catalyst 3 increased to 190 ppm at the intermediate point b between the precious metal-impregnated catalyst 3 and the NOx purification catalyst 4. On the other hand, NO, which was 494 ppm at point a,
At point b, the amount corresponding to the increased amount of NO 2 is lost,
It has decreased to 357 ppm. Then, at the point c after passing through the NOx purification catalyst 4, the NOx amount of NO and NO 2 combined is 49.5 with respect to the NOx amount at the point a.
% (NOx purification rate 50.5%). Also,
HC is not so purified by the precious metal-impregnated catalyst 3,
Although reaching the NOx purification catalyst 4, 66.1% is purified at the point c with respect to the point a.
【００２９】次に、上記第１実施例の排気ガス浄化装置
Ａに対する排気ガスの浄化性能テストと比較するため、
上記排気ガス浄化装置Ａの貴金属含浸触媒３を取り外
し、ＮＯｘ浄化用触媒４のみで排気ガスを浄化させた。
その結果を表２に示す。なお、テスト条件は、上記排気
ガス浄化装置Ａの場合と同じくし、ＮＯｘ浄化用触媒４
の前後で排気ガスの組成を測定した。Next, for comparison with the exhaust gas purification performance test for the exhaust gas purification apparatus A of the first embodiment,
The precious metal-impregnated catalyst 3 of the exhaust gas purification apparatus A was removed, and the exhaust gas was purified only by the NOx purification catalyst 4.
The results are shown in Table 2. The test conditions were the same as those for the exhaust gas purifying apparatus A, and the NOx purifying catalyst 4 was used.
The exhaust gas composition was measured before and after.
【００３０】[0030]
【表２】 表２から分かるように、ＮＯおよびＮＯ２ともにＮＯｘ
浄化用触媒４の前後で減少したものの、ＮＯｘ全体の浄
化率は４２．６％という低い値にとどまった。また、Ｈ
Ｃの浄化率も上記排気ガス浄化装置Ａに比べて低く、６
１．６％であった。[Table 2] As can be seen from Table 2, both NO and NO 2 are NOx.
Although it decreased before and after the purification catalyst 4, the overall purification rate of NOx remained as low as 42.6%. Also, H
The purification rate of C is also lower than that of the exhaust gas purification apparatus A, which is 6
It was 1.6%.
【００３１】次に、上記第２実施例の排気ガス浄化装置
Ｂについても、上記排気ガス浄化装置Ａと同様の浄化性
能テストを行った。その結果を表３に示す。表３では、
図２中の排気ガス浄化装置Ｂのガス入り口地点ｄとガス
出口地点ｅ点における排気ガスの組成を示した。テスト
条件は、上記排気ガス浄化装置Ａの場合と同様であり、
三元触媒５中のＰｔおよびＲｈの担持量は、担当１．１
リットル当たり１．２ｇとし、ＰｔとＲｈとの重量比を
５：１とした。Next, the exhaust gas purifying apparatus B of the second embodiment was also subjected to the same purifying performance test as that of the exhaust gas purifying apparatus A. The results are shown in Table 3. In Table 3,
The composition of the exhaust gas at the gas inlet point d and the gas outlet point e of the exhaust gas purification apparatus B in FIG. 2 is shown. The test conditions are the same as in the case of the exhaust gas purification device A,
The supported amount of Pt and Rh in the three-way catalyst 5 was 1.1.
It was 1.2 g per liter, and the weight ratio of Pt and Rh was 5: 1.
【００３２】[0032]
【表３】 表３から分かるように、上記排気ガス浄化装置Ｂのガス
出口地点ｅでは、ガス入り口地点ｄに比べて、ＮＯｘ全
体の浄化率は５２．３％を示し、ＨＣについては９０．
３％、ＣＯについては８８．２％がそれぞれ浄化され
た。[Table 3] As can be seen from Table 3, at the gas outlet point e of the exhaust gas purifying apparatus B, the purification rate of NOx as a whole is 52.3% and at 90.degree.
3% and 88.2% of CO were purified respectively.
【００３３】[0033]
【発明の効果】以上のように、請求項１記載の排気ガス
浄化装置によれば、排気ガスのＮＯｘ中のＮＯが反応性
に優れたＮＯ２に転化された後、このＮＯ２がＨＣの働
きでＮＯｘ還元反応を促進させたＮＯｘ浄化用触媒によ
り積極的に還元反応を起こすため、これまで浄化されに
くかったＮＯがＮＯ２に転化した状態で積極的に浄化さ
れ、ＮＯｘ全体としての浄化率を向上させることができ
る。As described above, according to the exhaust gas purifying apparatus of claim 1, after NO in NOx of the exhaust gas is converted into NO 2 having excellent reactivity, this NO 2 is converted into HC. Since the NOx purification catalyst that promotes the NOx reduction reaction by action causes the reduction reaction positively, the NO, which has been hard to be purified until now, is positively purified in the state of being converted to NO 2, and the purification rate of NOx as a whole Can be improved.
【００３４】特に、請求項３記載の排気ガス浄化装置に
よれば、ＮＯｘが浄化された排気ガスは、さらに三元触
媒によりＨＣおよびＣＯが浄化される。この結果、排気
ガス中の有害成分を満遍なく浄化することができる。Particularly, according to the exhaust gas purifying apparatus of the third aspect, the exhaust gas from which NOx has been purified is further purified from HC and CO by the three-way catalyst. As a result, the harmful components in the exhaust gas can be purified evenly.
【図１】本発明の第１実施例に係る排気ガス浄化装置を
示す構成図である。FIG. 1 is a configuration diagram showing an exhaust gas purifying apparatus according to a first embodiment of the present invention.
【図２】本発明の第２実施例に係る排気ガス浄化装置を
示す構成図である。FIG. 2 is a configuration diagram showing an exhaust gas purification device according to a second embodiment of the present invention.
【図３】排気ガス中のＮＯｘ成分に占めるＮＯの割合と
ＮＯｘ全体の浄化率との関係を示すグラフである。FIG. 3 is a graph showing the relationship between the proportion of NO in NOx components in exhaust gas and the purification rate of NOx as a whole.
２ 排気路 ３ 貴金属含浸触媒 ４ ＮＯｘ浄化用触媒 ５ 三元触媒 2 Exhaust passage 3 Noble metal impregnated catalyst 4 NOx purification catalyst 5 Three-way catalyst
Claims (3)
化させにくい性質を有しかつＮＯを酸化させる貴金属含
浸触媒と、上記排気路の上記貴金属含浸触媒より下流側
に設けられ、ＮＯｘを還元するＮＯｘ浄化用触媒とを備
えたことを特徴とする排気ガス浄化装置。1. A noble metal-impregnated catalyst that is provided in an exhaust gas exhaust passage and has a property of hardly oxidizing HC and oxidizes NO, and NOx that is provided in the exhaust passage downstream of the noble metal impregnated catalyst. An exhaust gas purification device comprising a NOx purification catalyst for reduction.
を含浸させてなるＰｔ含浸Ａ型ゼオライトである請求項
１記載の排気ガス浄化装置。2. The exhaust gas purifying apparatus according to claim 1, wherein the noble metal-impregnated catalyst is Pt-impregnated A-type zeolite obtained by impregnating A-type zeolite with platinum.
側に、三元触媒が配設されている請求項１または２記載
の排気ガス浄化装置。3. The exhaust gas purifying apparatus according to claim 1, wherein a three-way catalyst is arranged downstream of the NOx purifying catalyst in the exhaust passage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4032531A JPH05228342A (en) | 1992-02-20 | 1992-02-20 | Purifier for exhaust gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4032531A JPH05228342A (en) | 1992-02-20 | 1992-02-20 | Purifier for exhaust gas |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05228342A true JPH05228342A (en) | 1993-09-07 |
Family
ID=12361529
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4032531A Pending JPH05228342A (en) | 1992-02-20 | 1992-02-20 | Purifier for exhaust gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05228342A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0773057A1 (en) * | 1995-11-09 | 1997-05-14 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying catalyst |
| JP2008272760A (en) * | 2008-06-12 | 2008-11-13 | Volvo Ab | Porous material, method, and device for catalytic conversion of exhaust gas |
-
1992
- 1992-02-20 JP JP4032531A patent/JPH05228342A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0773057A1 (en) * | 1995-11-09 | 1997-05-14 | Toyota Jidosha Kabushiki Kaisha | Exhaust gas purifying catalyst |
| JP2008272760A (en) * | 2008-06-12 | 2008-11-13 | Volvo Ab | Porous material, method, and device for catalytic conversion of exhaust gas |
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