JP3328318B2 - Exhaust gas purification method - Google Patents

Exhaust gas purification method

Info

Publication number
JP3328318B2
JP3328318B2 JP13090492A JP13090492A JP3328318B2 JP 3328318 B2 JP3328318 B2 JP 3328318B2 JP 13090492 A JP13090492 A JP 13090492A JP 13090492 A JP13090492 A JP 13090492A JP 3328318 B2 JP3328318 B2 JP 3328318B2
Authority
JP
Japan
Prior art keywords
exhaust gas
catalyst
earth metal
alkaline earth
platinum
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 - Lifetime
Application number
JP13090492A
Other languages
Japanese (ja)
Other versions
JPH05317652A (en
Inventor
孝明 金沢
恒幸 谷澤
達司 水野
哲 井口
健治 加藤
俊明 田中
伸一 竹島
哲郎 木原
秀昭 村木
博文 新庄
基久 斎木
光一 笠原
修士 立石
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cataler Corp
Toyota Motor Corp
Toyota Central R&D Labs Inc
Original Assignee
Cataler Corp
Toyota Motor Corp
Toyota Central R&D Labs Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Cataler Corp, Toyota Motor Corp, Toyota Central R&D Labs Inc filed Critical Cataler Corp
Priority to JP13090492A priority Critical patent/JP3328318B2/en
Publication of JPH05317652A publication Critical patent/JPH05317652A/en
Application granted granted Critical
Publication of JP3328318B2 publication Critical patent/JP3328318B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【産業上の利用分野】本発明は排気ガスの浄化方法に関
し、更に詳しくは、酸素過剰下の排気ガス、即ち排気ガ
ス中に含まれる一酸化炭素、水素及び炭化水素等の還元
性物質を完全に酸化させるのに必要な酸素量よりも過剰
な量の酸素が含まれている排気ガス中の窒素酸化物(NO
x)を効率よく浄化する方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying exhaust gas, and more particularly, to exhaust gas with excess oxygen, that is, a method for completely reducing reducing substances such as carbon monoxide, hydrogen and hydrocarbons contained in exhaust gas. Nitrogen oxides (NO) in exhaust gas containing an excess amount of oxygen in excess of that required to oxidize
The present invention relates to a method for efficiently purifying x).

【0002】[0002]

【従来の技術】従来、自動車の排気ガス浄化用触媒とし
て排気ガス中の一酸化炭素(CO) 及び炭化水素(HC) の
酸化と、窒素酸化物(NOx) の還元とを同時に行なって排
気ガスを浄化する排気ガス浄化用三元触媒が数多く知ら
れている。このような触媒としては、例えばコージェラ
イトなどの耐火性担体にγ−アルミナスラリーを塗布、
焼成し、パラジウム、白金、ロジウムなどの貴金属を担
持させたものが典型的である。(例えば特公昭56-27295
号公報など参照)
2. Description of the Related Art Conventionally, as a catalyst for purifying an exhaust gas of an automobile, the oxidation of carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas and the reduction of nitrogen oxide (NOx) in the exhaust gas have been simultaneously carried out. There are many known three-way catalysts for purifying exhaust gas. As such a catalyst, for example, a γ-alumina slurry is applied to a refractory support such as cordierite,
Typically, it is baked to support a noble metal such as palladium, platinum, and rhodium. (For example, Japanese Patent Publication No. 56-27295
No.)

【0003】ところで、前記排気ガス浄化用触媒の性能
はエンジンの設定空燃比によって大きく左右され、希薄
混合気、つまり空燃比の大きいリーン側では燃焼後の排
気ガス中の酸素量が多くなり、酸化作用が活発に、還元
作用が不活発になる。逆に、空燃比の小さいリッチ側で
は燃焼後の排気ガス中の酸素量が少なくなり、酸化作用
が不活発に、還元作用が活発になる。一方、近年、自動
車の低燃費化の要請に応えて通常走行時になるべく酸素
過剰の混合気で燃焼させるリーン側での運転が行なわれ
ており、リーン側でも十分にNOx を浄化できる触媒が望
まれていた。
[0003] The performance of the exhaust gas purifying catalyst is greatly affected by the set air-fuel ratio of the engine. On the lean side, that is, on the lean side where the air-fuel ratio is large, the amount of oxygen in the exhaust gas after combustion increases, and The action becomes active and the reducing action becomes inactive. Conversely, on the rich side where the air-fuel ratio is small, the amount of oxygen in the exhaust gas after combustion decreases, and the oxidizing action becomes inactive and the reducing action becomes active. On the other hand, in recent years, in response to the demand for lower fuel consumption of automobiles, lean-side operation of burning with an oxygen-excess mixture as much as possible during normal driving has been performed, and a catalyst that can sufficiently purify NOx on the lean side is also desired. I was

【0004】かかる状況下に酸素過剰雰囲気下の自動車
排気ガス浄化用触媒として、一酸化炭素(CO) 及び炭化
水素(HC) の酸化と、窒素酸化物(NOx) の還元を同時に
行なう触媒が種々提案されている。このような触媒とし
て、例えばアルミナ担体に白金を担持したPt/Al2O3触媒
が提案されている(例えば1991年4月11日付日本工業新
聞参照)。しかしながら、この触媒は、酸素過剰雰囲気
下において実用上十分な浄化率を示す触媒とはいえなか
った。
Under such circumstances, various catalysts for simultaneously oxidizing carbon monoxide (CO) and hydrocarbons (HC) and reducing nitrogen oxides (NOx) have been used as catalysts for purifying automobile exhaust gas in an oxygen-excess atmosphere. Proposed. As such a catalyst, for example, a Pt / Al 2 O 3 catalyst in which platinum is supported on an alumina carrier has been proposed (for example, see the Nihon Kogyo Shimbun on April 11, 1991). However, this catalyst was not a catalyst showing a practically sufficient purification rate in an oxygen-excess atmosphere.

【0005】一方、本出願人らは、先に、定常走行時及
び過渡状態時(市街地走行模擬状態)においてNOX 浄化
率を高めるべくアルミナ担体に白金及びLa2O3 を担持し
た触媒を提案した(特願平3−344781号明細書参照)。
しかしながら、この触媒は、高温で耐久処理すると浄化
率が低下し、必ずしも必要十分な浄化率は得られなかっ
た。
On the other hand, the present applicants have previously proposed a catalyst in which platinum and La 2 O 3 are supported on an alumina carrier in order to increase the NO X purification rate during steady running and in a transient state (simulated running in an urban area). (See Japanese Patent Application No. 3-34481).
However, when the catalyst was subjected to a durability treatment at a high temperature, the purification rate was lowered, and a necessary and sufficient purification rate was not always obtained.

【0006】[0006]

【発明が解決しようとする課題】自動車の走行中のエン
ジンから排出される排気ガス組成は、理論A/F値近傍
からオーバーリーンのA/F値 (約23) までの範囲内で
頻繁に変化する。従って、本発明は、前記した従来技術
の問題点を排除し、上記した実際の自動車等の走行状態
(A/F値の過渡の連続) において、排気ガス中のNOx
、CO及びHCを効率よく浄化することができる排気ガス
の浄化方法を提供することを目的とする。
The composition of the exhaust gas emitted from the engine while the vehicle is running frequently changes within a range from the vicinity of the theoretical A / F value to the overlean A / F value (about 23). I do. Therefore, the present invention eliminates the above-mentioned problems of the prior art, and describes the actual running state of an automobile or the like.
(Continuous transition of A / F value), NOx in exhaust gas
It is an object of the present invention to provide an exhaust gas purification method capable of efficiently purifying CO, HC and HC.

【0007】[0007]

【課題を解決するための手段】本発明に従えば、酸素過
剰雰囲気下における排気ガス中の一酸化炭素(CO)、炭
化水素(HC) および窒素酸化物(NOX ) を同時に浄化す
る排気ガス浄化方法であって、酸素過剰の排気ガスを、
多孔質体からなる担体に、バリウム、カルシウム及びマ
グネシウムから選ばれたアルカリ土類金属の酸化物およ
び白金(Pt)を担持してなり、前記アルカリ土類金属酸
化物の担持量がハニカムの体積1リットルあたりアルカ
リ土類金属として0.05〜10モルである排気ガス浄化用触
媒と接触させることから成る排気ガスの浄化方法が提供
される。
According to the present invention, in order to solve the problems], oxygen carbon monoxide in the exhaust gas in excess atmosphere (CO), the exhaust gas purifying hydrocarbon (HC) and nitrogen oxides (NO X) at the same time A purification method, wherein exhaust gas with excess oxygen is
Barium, calcium and magnesium are deposited on a porous carrier .
Ri Na and oxide Oyo <br/> beauty carrying platinum (Pt) of alkaline earth metals selected from magnesium, the alkaline earth metal oxide
Per liter of honeycomb volume
An exhaust gas purification method is provided, which comprises contacting with an exhaust gas purification catalyst having 0.05 to 10 moles as an earth metal .

【0008】以下に説明するように、本発明の排気ガス
浄化方法によれば、希薄燃焼エンジンを搭載した車両か
ら排出される排気ガス中のCO、HC及びNOx を過渡状態
(市街地走行模擬状態)においても高効率で浄化するこ
とができる。
As described below, according to the exhaust gas purifying method of the present invention, CO, HC and NOx in the exhaust gas discharged from a vehicle equipped with a lean burn engine are in a transient state (simulated state in urban area running). Can be purified with high efficiency.

【0009】本発明の排気ガス浄化方法に用いる触媒は
活性金属として、白金(Pt) と、バリウム(Ba)、カルシ
ウム(Ca)及びマグネシウム(Mg)から選ばれたアルカリ土
類金属(以下、単にアルカリ土類金属ということがあ
る)の酸化物を用い、これらを多孔質担体に担持させて
使用する。
The catalyst used in the exhaust gas purifying method of the present invention includes platinum (Pt), barium (Ba) and calcium as active metals.
Alkaline earth selected from calcium (Ca) and magnesium (Mg)
Class metals (hereinafter sometimes simply referred to as alkaline earth metals)
) And supported on a porous carrier for use.

【0010】本発明において用いることのできる多孔質
担体としては、アルミナ、ゼオライト、ジルコニア、シ
リカアルミナ、シリカ等をあげることができる。これら
の多孔質担体の種類及び物性については特に限定はな
く、従来から触媒用として使用されていた任意の多孔質
担体を使用することができる。また、これらの多孔質担
体はコージェライト、耐熱金属合金等からなるハニカム
基体にコートして用いても良い。
As the porous carrier usable in the present invention, alumina, zeolite, zirconia, silica-alumina, silica and the like can be mentioned. There is no particular limitation on the type and physical properties of these porous carriers, and any porous carriers conventionally used for catalysts can be used. Further, these porous carriers may be used after being coated on a honeycomb substrate made of cordierite, a heat-resistant metal alloy or the like.

【0011】本発明に係る排気ガス浄化用触媒は、前記
した多孔質担体に、白金と前記アルカリ土類金属の酸化
を担持してなる。これら金属の担持量には特に限定は
ないが、アルカリ土類金属酸化物の担持量は、アルカリ
土類金属として0.05〜10.0 mol/リットルである。この
アルカリ土類金属酸化物の担持量が 0.05mol/リットル
未満の場合、十分な NOx浄化率を得ることができず、ま
た、10.0 mol/リットルを超えると担体の表面積を低下
させるので好ましくない。好ましくは、0.15〜5.0mol/
リットルである。
[0011] The exhaust gas purifying catalyst according to the present invention is a catalyst for oxidizing platinum and the alkaline earth metal on the porous carrier.
An object is carried. The loading amount of these metals is not particularly limited, but the loading amount of the alkaline earth metal oxide is 0.05 to 10.0 mol / liter as the alkaline earth metal. If the supported amount of the alkaline earth metal oxide is less than 0.05 mol / l, a sufficient NOx purification rate cannot be obtained, and if it exceeds 10.0 mol / l, the surface area of the carrier decreases.
Is not preferred . Preferably, 0.15 to 5.0 mol /
Liters.

【0012】本発明に係る排気ガス浄化用触媒における
白金の担持量には特に限定はないが、 0.1〜10.0g/リ
ットルであることが好ましい。この白金の担持量が 0.1
g/リットル未満の場合には、十分な触媒活性が得られ
ない恐れがあり、また、10.0g/リットルを超えると、
それ以上白金の担持量を増加させても白金の粒成長が促
進され、活性向上は僅かで高価となるのみである。白金
の担持量が 0.5〜 3.0g/リットルである場合は、活性
とコストの面で特に好ましい。
It not particularly limited to the amount of supported platinum in the exhaust gas purifying catalyst according to [0012] the present invention, but is preferably a 0.1~10.0G / liter. The amount of supported platinum is 0.1
If the amount is less than g / liter, sufficient catalytic activity may not be obtained.
Even if the amount of supported platinum is further increased, the grain growth of platinum is promoted, and the activity is slightly increased and the cost is increased. When the amount of supported platinum is 0.5 to 3.0 g / liter, it is particularly preferable in terms of activity and cost.

【0013】本発明において使用する排気ガス浄化用触
媒の製造方法については、特に限定はなく、従来の一般
的方法に準ずることができる。例えば常法に従って調製
したアルミナを含有するスラリー中にコージェライトか
らなる基体を浸漬して表面にアルミナをコートし乾燥焼
成(例えば温度 600〜 700℃) 後、ジニトロジアミン白
金、塩化白金酸などの白金化合物の水溶液に浸漬し、乾
燥焼成(例えば温度 200〜 500℃) して多孔質担体に白
金を担持させ、更にアルカリ土類金属の酢酸塩などの水
溶性アルカリ土類金属化合物の水溶液に浸漬し、乾燥焼
成(例えば温度600〜 700℃) してアルカリ土類金属を
担持させて製造することができる。
The method for producing the exhaust gas purifying catalyst used in the present invention is not particularly limited, and can be according to a conventional general method. For example, a substrate made of cordierite is immersed in a slurry containing alumina prepared according to a conventional method to coat the surface with alumina, dried and fired (for example, at a temperature of 600 to 700 ° C.), and then coated with platinum such as dinitrodiamine platinum or chloroplatinic acid. Immersed in an aqueous solution of the compound, dried and fired (for example, at a temperature of 200 to 500 ° C.) to support platinum on the porous carrier, and further immersed in an aqueous solution of a water-soluble alkaline earth metal compound such as an alkaline earth metal acetate. It can be manufactured by drying and firing (for example, at a temperature of 600 to 700 ° C.) to carry an alkaline earth metal.

【0014】また、別法として、アルミナとアルカリ土
類金属酸化物を含有するスラリー中に基体を浸漬してア
ルミナをコートし、乾燥焼成後、ジニトロジアミン白
金、塩化白金酸などの白金化合物の水溶液に浸漬し、乾
燥焼成し、アルカリ土類金属と白金を担持させて製造す
ることができる。なお、アルカリ土類金属は使用される
環境によって水酸化物などになる場合もある。
Alternatively, the substrate is immersed in a slurry containing alumina and an alkaline earth metal oxide to coat the alumina, dried and fired, and then an aqueous solution of a platinum compound such as dinitrodiamine platinum or chloroplatinic acid is applied. , Dried and fired, and supported by an alkaline earth metal and platinum. Note that the alkaline earth metal may become a hydroxide or the like depending on the environment in which it is used.

【0015】本発明に係る排気ガス浄化方法において排
気ガスを浄化するにあたっては、希薄燃焼エンジンの排
気通路において触媒を設置する場所には特に限定はない
が、例えば車両の床下、スタート触媒または三元触媒の
下流側の床下などに配置するのが好ましい。
In purifying the exhaust gas in the exhaust gas purifying method according to the present invention, the place where the catalyst is installed in the exhaust passage of the lean burn engine is not particularly limited. It is preferable to arrange it under the floor downstream of the catalyst.

【0016】本発明に係る浄化方法は通常の方法で実施
することができ、排気ガスを触媒層に導入する空間速度
(SV)にも特に限定はなく、例えば 300,000〜10,000hr-1
の範囲が好ましく、また触媒層温度にも特に制限はない
が、 200〜 500℃程度の温度が好ましい。
The purification method according to the present invention can be carried out in a usual manner, and the space velocity at which exhaust gas is introduced into the catalyst layer
(SV) is not particularly limited, for example, 300,000 to 10,000 hr -1
The temperature of the catalyst layer is not particularly limited, but a temperature of about 200 to 500 ° C. is preferable.

【0017】[0017]

【作用】本発明に従って、アルカリ土類金属酸化物と白
金とを多孔質担体に担持した触媒を用い、これを希薄燃
焼する内燃機関の排気通路に設置すると、以下の実施例
にも示すように、車両走行時に、CO、HC及びNOx を高効
率で浄化できる。本発明に係る排気ガスの浄化方法が優
れた効果を発揮するメカニズムについては、未だ必ずし
も明らかではないが、次のように考えられる。
According to the present invention, when a catalyst in which an alkaline earth metal oxide and platinum are supported on a porous carrier is used and installed in an exhaust passage of an internal combustion engine that performs lean combustion, as shown in the following examples, In addition, CO, HC and NOx can be purified with high efficiency when the vehicle is running. The mechanism by which the exhaust gas purifying method according to the present invention exerts an excellent effect is not necessarily clear yet, but is considered as follows.

【0018】本発明による触媒の構成は、例えばアルミ
ナなどの多孔質担体の表面に酸化バリウム(BaO) 、酸化
マグネシウム(MgO)、酸化カルシウム(CaO)などのアル
カリ土類金属の酸化物と白金が担持されており、かかる
構成の触媒は車両走行時のエンジン排出ガスの組成変化
に対して次のように作用するものと想定する。
The structure of the catalyst according to the present invention is such that an alkaline earth metal oxide such as barium oxide (BaO), magnesium oxide (MgO), calcium oxide (CaO) and platinum are formed on the surface of a porous carrier such as alumina. It is assumed that the catalyst that is carried and has such a structure acts as follows on a change in the composition of the engine exhaust gas when the vehicle is running.

【0019】車両停止時:A/Fは理論A/F近傍で排
気ガス中には NOxが少ない。触媒上ではアルカリ土類金
属酸化物に吸着されていた NOxがPtに移動(逆スピルオ
ーバー)し、排気ガス中の還元ガス(CO、H2 、HC) と
反応し、NOx はN2 に還元され、この際、還元ガスも浄
化される。アルカリ土類金属酸化物に吸着された NOxが
無くなれば、Pt上に還元ガスが吸着される。
When the vehicle is stopped: The A / F is near the theoretical A / F, and there is little NOx in the exhaust gas. Moving the NOx which has been adsorbed on the alkaline earth metal oxide is Pt in the catalyst (reverse spillover), reacts with the reducing gas in the exhaust gas (CO, H 2, HC), NOx is reduced to N 2 At this time, the reducing gas is also purified. If NOx adsorbed on the alkaline earth metal oxide disappears, the reducing gas will be adsorbed on Pt.

【0020】車両加速時:A/Fは理論A/F近傍から
リーン(A/F=23)まで連続的に変化し、排気ガス中
にNOX が多量に存在することになる。触媒上では排気ガ
ス中のNOX がPtに吸着した還元ガスによりN2 に還元さ
れ、この際、還元ガスも浄化される。
During vehicle acceleration: The A / F continuously changes from near the theoretical A / F to lean (A / F = 23), and a large amount of NO X is present in the exhaust gas. Is on the catalyst is reduced to N 2 by the reducing gas NO X in the exhaust gas is adsorbed to Pt, this time, the reducing gas is also purified.

【0021】定常走行時:A/Fはリーン(A/F=2
3)状態で、排気ガス中のNOX は加速時よりも少なく、H
Cは多めとなり、NOX はHCによりN2 に還元される。こ
の際、HCも浄化され、また、反応しないNOX は担体上の
アルカリ土類金属酸化物に吸着される。このリーン状態
におけるNOX の吸着量がランタン(La)より非常に大き
いため、本発明の浄化方法ではNOX 浄化能が高いものと
思われる。
During steady running: A / F is lean (A / F = 2
3) In the state, the NO X in the exhaust gas is lower than during acceleration,
C becomes larger and NO X is reduced to N 2 by HC. At this time, HC is also purified, and unreacted NO X is adsorbed on the alkaline earth metal oxide on the carrier. Since the adsorption amount of NO X in this lean state is much larger than that of lanthanum (La), it is considered that the purification method of the present invention has high NO X purification ability.

【0022】減速時:A/Fはオートマティック(A/
T)車では理論A/F近傍であり、マニュアル(M/
T)車では酸化雰囲気(燃料カット)となり、排気ガス
中のNO X は少ない。触媒上ではA/T車の場合は車両停
止時と同じ状態になり、M/T車の場合にはNOX はアル
カリ土類金属酸化物に吸着保持される。
During deceleration: A / F is automatic (A / F
T) For vehicles, it is near theoretical A / F, and manual (M /
T) Cars have an oxidizing atmosphere (fuel cut) and exhaust gas
NO in XIs less. A / T vehicle stops on catalyst
It will be in the same state as when stopped, NO for M / T vehiclesXIs al
Adsorbed and held on potassium earth metal oxide.

【0023】[0023]

【実施例】以下、実施例に従って、本発明を更に詳しく
説明するが、本発明の範囲をこれらの実施例に限定する
ものでないことはいうまでもない。以下の例において
「部」は特にことわらない限り「重量部」を示す。
EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the scope of the present invention is not limited to these Examples. In the following examples, “parts” means “parts by weight” unless otherwise specified.

【0024】実施例1 担持量の異なるPt/酸化バリウム/アルミナのハニカム
触媒を調製し、NOX 浄化活性を比較した。a) アルミナ・スラリーの調製 アルミナ粉末 100部に、アルミナゾル(アルミナ含有率
10重量%)70部、40重量%硝酸アルミニウム水溶液15部
および水30部を加えて攪拌混合し、コーティング用スラ
リーを調製した。
[0024] The honeycomb catalyst of the different Pt / barium oxide / alumina of Example 1 supported amount were prepared and compared NO X purification activity. a) Preparation of alumina slurry Alumina sol (alumina content
10 parts by weight), 70 parts of a 40% by weight aqueous solution of aluminum nitrate and 30 parts of water were added and mixed by stirring to prepare a slurry for coating.

【0025】b) コーティング及び焼成 コージェライト製ハニカム基体を水に浸漬し、余分な水
を吹き払った後、上記a)で得られたスラリーに浸漬
し、取り出した後、余分なスラリーを吹き払い、温度80
℃で20分間乾燥し、更にこれを 600℃で1時間焼成し
た。アルミナのコート量はハニカムの体積1リットル当
たり 120g であった。
B) Coating and firing The honeycomb substrate made of cordierite is immersed in water, and excess water is blown off. Then, the honeycomb substrate is immersed in the slurry obtained in the above a), taken out, and then the excess slurry is blown off. , Temperature 80
After drying at 20 ° C. for 20 minutes, it was fired at 600 ° C. for 1 hour. The coating amount of alumina was 120 g per liter of the honeycomb volume.

【0026】c) Ptの担持 上記のようにして得られたハニカム担体を、表1に示す
Pt担持量が得られるように調製した所定濃度のジニトロ
ジアミン白金の水溶液に浸漬し、 250℃で乾燥して表1
に示すPtの担持量を持つ触媒を調製した。
C) Loading of Pt The honeycomb carrier obtained as described above is shown in Table 1.
It was immersed in an aqueous solution of dinitrodiamineplatinum of a predetermined concentration prepared so as to obtain a supported amount of Pt, dried at 250 ° C, and dried.
A catalyst having the supported amount of Pt shown in the following was prepared.

【0027】d)表1に示すBa担持量が得られるように
調製した所定濃度の酢酸バリウム水溶液に前記白金担持
担体を浸漬し、乾燥後、 600℃で1時間焼成し、表1の
触媒No.2〜13の本発明の触媒を得た。比較触媒としてN
o.1及び14〜17の触媒も上記実施例に準じた方法で併せ
調製した。
D) The platinum-supported carrier was immersed in an aqueous barium acetate solution having a predetermined concentration prepared so as to obtain the amount of Ba shown in Table 1, dried, and calcined at 600 ° C. for 1 hour. 0.2 to 13 catalysts of the invention were obtained. N as comparative catalyst
The catalysts of o.1 and 14 to 17 were also prepared by the method according to the above example.

【0028】 表1:調製触媒 ────────────────────────── 担持量 触媒No. Ba(mol/ リットル) Pt(g/リットル) 1 0.03 2.0 2 0.15 2.0 3 0.2 2.0 4 0.3 2.0 5 0.5 2.0 6 1.0 2.0 7 10.0 2.0 8 0.2 0.5 9 0.2 1.0 10 0.2 5.0 11 0.2 10.0 12 0.05 2.0 13 0.1 2.0 14 0 1.0 15 0 2.0 16 0 10.0 17 11.0 2.0 ────────────────────────── (注)触媒2〜13 : 実施例 触媒1及び14〜17 : 比較例 Table 1: Prepared catalyst No. Supported catalyst No. Ba (mol / liter) Pt (g / liter ) ) 1 0.03 2.0 2 0.15 2.0 3 0.2 2.0 4 0.3 2.0 5 0.5 0.5 2.0 6 1.0 2.0 7 10.0 2.0 8 0.2 0.5 9 0.2 1.0 10 10 0.2 5.0 11 0.2 10.0 10.0 12 0.05 2.0 13 13 0.1 2.0 140 0 1.0 150 2 0.0 16 0 10.0 17 11.0 2.0 ────────────────────────── (Note) Catalysts 2 to 13: Examples Catalysts 1 and 14-17: Comparative Example

【0029】浄化性能の評価 上記触媒の浄化性能を下記条件で評価した。 エミッション評価 希薄燃焼エンジン( 1.6リットル)搭載車両の排気通路
に上記触媒を設置し、市街地走行モードで走行して、C
O、HC及びNOx の浄化率を測定し、結果を表3に示す。
尚、耐久処理触媒とは、希薄燃焼エンジン(1.6 リット
ル)の排気通路に上記触媒を設置し、エンジンをA/F
=18、入りガス温度 650℃で50時間運転したものであ
る。
Evaluation of Purification Performance The purification performance of the above catalyst was evaluated under the following conditions. Emission evaluation Installed the above catalyst in the exhaust passage of a vehicle equipped with a lean burn engine (1.6 liter),
O, it was measured purification rate of HC and NO x, and the results are shown in Table 3.
The endurance treatment catalyst is a catalyst that is installed in the exhaust passage of a lean burn engine (1.6 liter) and the engine is A / F
= 18, operated for 50 hours at an incoming gas temperature of 650 ° C.

【0030】 表2:浄化性能の評価 ─────────────────────────────── 初期触媒の浄化率(%) 耐久処理触媒の浄化率(%) 触媒No. NOX HC CO NOX HC CO 1 42 96 100 24 89 94 2 92 95 100 42 88 97 3 92 96 100 47 89 96 4 93 95 100 50 88 98 5 93 93 100 52 86 98 6 93 90 100 53 83 97 7 74 93 99 30 84 95 8 88 94 100 39 82 94 9 90 97 100 44 86 97 10 93 98 100 47 94 99 11 93 98 100 48 95 99 12 66 96 100 28 90 96 13 90 96 100 30 89 93 14 38 97 100 12 88 91 15 46 98 100 18 90 92 16 49 98 100 21 93 96 17 52 89 97 18 87 91 ───────────────────────────── (注)触媒2〜13 : 実施例 触媒1及び14〜17 : 比較例 Table 2: Evaluation of purification performance性能Purification rate (%) durability of initial catalyst Purification rate of treated catalyst (%) Catalyst No. NO X HC CO NO X HC CO 142 96 100 24 89 94 2 92 95 100 42 88 97 3 92 96 100 47 89 96 4 93 95 100 50 88 98 5 93 93 100 52 86 98 6 93 90 100 53 83 97 7 74 93 99 30 84 95 8 88 94 100 39 82 94 9 90 97 100 44 86 97 10 93 98 100 47 94 99 11 93 98 100 48 95 99 12 66 96 100 28 90 96 13 90 96 100 30 89 93 14 38 97 100 12 88 91 15 46 98 100 18 90 92 16 49 98 100 21 93 96 17 52 89 97 18 87 91 ──────────── ───────────────── (Note) Catalyst 2-13: Example Catalyst 1 and 14-17: Comparative example

【0031】上記結果から明らかなように、本発明によ
る排気ガス浄化方法によれば、希薄燃焼エンジンを搭載
した車両から排出される排気ガス中のNOx 、CO及びHCを
耐久処理後も劣化が少なく効率よく浄化することがで
き、特に、触媒中のアルカリ土類金属の担持量が0.15〜
1.0mol/リットルで、白金の担持量が 0.5〜 7.0g /リ
ットルであるのが好ましい。
As is clear from the above results, according to the exhaust gas purification method of the present invention, NO x , CO and HC in exhaust gas discharged from a vehicle equipped with a lean burn engine are not deteriorated even after endurance treatment. The catalyst can be purified efficiently with a small amount.
It is preferable that the amount of platinum supported is 1.0 mol / liter and the supported amount of platinum is 0.5 to 7.0 g / liter.

【0032】実施例2 実施例1において、酢酸バリウムに代えて硝酸カルシウ
ム、また同様に酢酸バリウムに代えて酢酸マグネシウム
を用いた以外は実施例1と同様にして、表3に示すよう
に、担持量の異なるPt/酸化カルシウム/アルミナ、Pt
/酸化マグネシウム/アルミナ及びPt/酸化カルシウム
+酸化マグネシウム/アルミナのハニカム触媒を各々調
製し、実施例1と同様に触媒の浄化活性を評価した。結
果を表4に示す。
Example 2 The procedure of Example 1 was repeated, except that calcium nitrate was used instead of barium acetate and magnesium acetate was used instead of barium acetate. Different amounts of Pt / calcium oxide / alumina, Pt
/ Honeycomb oxide / alumina and Pt / calcium oxide + magnesium oxide / alumina were prepared, and the purification activity of the catalyst was evaluated in the same manner as in Example 1. Table 4 shows the results.

【0033】 表3:調製触媒 ─────────────────────────────── 担 持 量 触媒No. Ca(mol/リットル) Mg(mol/リットル) Pt(g/リットル) 18 0.03 − 2.0 19 0.05 − 2.0 20 0.1 − 2.0 21 0.15 − 2.0 22 0.2 − 2.0 23 0.3 − 2.0 24 0.5 − 2.0 25 1.0 − 2.0 26 10.0 − 2.0 27 0.2 − 0.5 28 0.2 − 1.0 29 0.2 − 5.0 30 0.2 − 10.0 31 11.0 − 2.0 32 − 0.15 2.0 33 − 0.2 2.0 34 − 0.3 2.0 35 − 0.5 2.0 36 − 1.0 2.0 37 0.1 0.1 2.0 ─────────────────────────────── Table 3: Prepared catalyst / loading amount Catalyst No. Ca (mol / liter) ) Mg (mol / liter) Pt (g / liter) 18 0.03-2.0 19 0.05-2.0 20 0.1-2.0 21 0.15-2.0 22 0.2-2.0 23 0.3-2.0 24 0.5-2.0 25 1.0-2.0 26 10.0-2.0 27 0.2-0.5 28 0.2-1.0 29 0.2-5.0 30 0.2-10.0 31 11.0-2.0 32-0.15 2.0 33-0.2 2.0 34-0.3 2.0 35-0.5 2.0 36-1.0 2.0 37 0.1 0.1 2.0 ─────── ────────────────────────

【0034】 表4:浄化性能の評価 ─────────────────────────────── 初期触媒の浄化率(%) 耐久処理触媒の浄化率(%) 触媒No. NOX HC CO NOX HC CO 18 38 95 100 23 87 96 19 72 96 100 25 87 95 20 89 95 100 32 89 93 21 90 94 100 46 88 98 22 93 96 100 48 86 97 23 92 96 100 48 89 98 24 92 95 100 50 87 96 25 94 95 100 52 84 97 26 69 91 100 28 85 96 27 89 93 100 41 82 93 28 90 95 100 44 85 97 29 92 98 100 46 92 99 30 92 99 100 46 94 99 31 54 90 96 15 83 95 32 67 95 100 30 89 98 33 67 97 100 35 89 98 34 67 97 100 36 91 99 35 68 95 100 36 90 99 36 68 92 100 35 88 97 37 91 95 100 47 89 97 ─────────────────────────────── Table 4: Evaluation of purification performance性能Purification rate (%) durability of initial catalyst Purification rate of treated catalyst (%) Catalyst No. NO X HC CO NO X HC CO 18 38 95 100 23 87 96 19 72 96 100 25 87 95 20 89 95 100 32 89 93 21 90 94 100 46 88 98 22 93 96 100 48 86 97 23 92 96 100 48 89 98 24 92 95 100 50 87 96 25 94 95 100 52 84 97 26 69 91 100 28 85 96 27 89 93 100 41 82 93 28 90 95 100 44 85 97 29 92 98 100 46 92 99 30 92 99 100 46 94 99 31 54 90 96 15 83 95 32 67 95 100 30 89 98 33 67 97 100 35 89 98 34 67 97 100 36 91 99 35 68 95 100 36 90 99 36 68 92 100 35 88 97 37 91 95 100 47 89 97 ───────────────────────────────

【0035】[0035]

【発明の効果】自動車は、実際の運転において、加減速
を繰り返すのが実状であり、かかる状況下に排出される
排気ガスに対し、本発明によれば、Ptの電子状態をアル
カリ土類金属の酸化物によりコントロールすることによ
り、HCとNox との反応活性を向上させることができ、更
に、アルカリ土類金属の酸化物のNox 吸着特性を利用
し、加減速におけるNox 浄化率を大きく向上させること
ができる。この結果、酸素過剰の排気ガス中のCO及びHC
を十分に浄化したもとで、同排気ガス中の窒素酸化物を
効率よく浄化することができる。
According to the present invention, the actual state of an automobile is that acceleration and deceleration are repeated during actual driving. According to the present invention, the electronic state of Pt is changed to an alkaline earth metal for exhaust gas discharged under such circumstances. of by controlling the oxide, it is possible to improve the reactivity of HC and No x, further utilizing the No x adsorption properties of the oxides of alkaline earth metals, a No x purification rate of acceleration and deceleration It can be greatly improved. As a result, CO and HC in the oxygen-excess exhaust gas
The nitrogen oxides in the exhaust gas can be efficiently purified with sufficient purification.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 谷澤 恒幸 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 水野 達司 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 井口 哲 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 加藤 健治 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 田中 俊明 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 竹島 伸一 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 木原 哲郎 愛知県豊田市トヨタ町1番地 トヨタ自 動車株式会社内 (72)発明者 村木 秀昭 愛知県愛知郡長久手町大字長湫字横道41 番地の1 株式会社豊田中央研究所内 (72)発明者 新庄 博文 愛知県愛知郡長久手町大字長湫字横道41 番地の1 株式会社豊田中央研究所内 (72)発明者 斎木 基久 愛知県愛知郡長久手町大字長湫字横道41 番地の1 株式会社豊田中央研究所内 (72)発明者 笠原 光一 静岡県小笠郡大東町千浜7800番地 キャ タラー工業株式会社内 (72)発明者 立石 修士 静岡県小笠郡大東町千浜7800番地 キャ タラー工業株式会社内 (56)参考文献 特開 昭60−190236(JP,A) 特開 平4−367713(JP,A) 特開 平4−284824(JP,A) 特開 平4−367724(JP,A) (58)調査した分野(Int.Cl.7,DB名) B01D 53/86 B01J 21/00 - 37/36 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuneyuki Tanizawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tatsushi Mizuno 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 72) Inventor Tetsu Iguchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Kenji Kato 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Toshiaki Tanaka Aichi Prefecture 1 Toyota Town, Toyota City Toyota Motor Corporation (72) Inventor Shinichi Takeshima 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Tetsuro Kihara 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor: Hideaki Muraki Inventor: Aichi, Nagakute-cho, Aichi-gun, Aichi Prefecture 1 Inside Toyota Central Research Institute Co., Ltd. (72) Inventor Hirofumi Shinjo 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture 1 Inside Toyota Central Research Institute Co., Ltd. 41 No. 1 Yokomichi, Toyota Central Research Laboratory Co., Ltd. (72) Koichi Kasahara 7800, Daito-cho, Chiba, Ogasa-gun, Shizuoka Prefecture Inside Cataler Industry Co., Ltd. No. 7800 Inside Cataler Industry Co., Ltd. (56) References JP-A-60-190236 (JP, A) JP-A-4-367713 (JP, A) JP-A-4-284824 (JP, A) JP-A-4 -367724 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) B01D 53/86 B01J 21/00-37/36

Claims (1)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】 酸素過剰雰囲気下における排気ガス中の
一酸化炭素、炭化水素および窒素酸化物を同時に浄化す
る排気ガスの浄化方法であって、酸素過剰の排気ガス
を、多孔質体からなる担体に、バリウム、カルシウム及
びマグネシウムから選ばれたアルカリ土類金属の酸化物
および白金を担持してなり、前記アルカリ土類金属酸化
物の担持量がハニカムの体積1リットルあたりアルカリ
土類金属として0.05〜10モルである排気ガス浄化用触媒
と接触させることを特徴とする排気ガスの浄化方法。
An exhaust gas purification method for simultaneously purifying carbon monoxide, hydrocarbons and nitrogen oxides in an exhaust gas in an oxygen-excess atmosphere, comprising the steps of: And barium, calcium and
The oxide <br/> and platinum alkaline earth metal selected from the fine magnesium Ri name carries, the alkaline earth metal oxide
The amount of material carried is alkali per liter of honeycomb volume.
A method for purifying exhaust gas, comprising contacting with an exhaust gas purifying catalyst having 0.05 to 10 mol as an earth metal .
JP13090492A 1992-05-22 1992-05-22 Exhaust gas purification method Expired - Lifetime JP3328318B2 (en)

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