JP2769515B2 - Exhaust gas purification catalyst - Google Patents
Exhaust gas purification catalystInfo
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- JP2769515B2 JP2769515B2 JP1083685A JP8368589A JP2769515B2 JP 2769515 B2 JP2769515 B2 JP 2769515B2 JP 1083685 A JP1083685 A JP 1083685A JP 8368589 A JP8368589 A JP 8368589A JP 2769515 B2 JP2769515 B2 JP 2769515B2
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- zsm
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は自動車の排気浄化用触媒、特に詳しくは空燃
比がリーン側となる酸素過剰雰囲気においてもNOxを高
率に浄化できる触媒に関するものである。The present invention relates to a catalyst for purifying exhaust gas from automobiles, and more particularly to a catalyst capable of purifying NOx at a high rate even in an oxygen-excess atmosphere where the air-fuel ratio is lean. is there.
自動車の排気浄化用触媒として、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
を同時に行う触媒が汎用されている。このような触媒は
基本的にはコージエライト等の耐火性担体にγ−アルミ
ナスラリーを塗布、焼成した後、Pd,Pt,Rh等の金属又は
その混合物を担持させたものである。又、その触媒活性
を高めるための提案が数多くなされており、例えば特開
昭61−11147号公報には、希土類酸化物で安定されたγ
−アルミナ粒子上に貴金属等を分散させるタイプの触媒
において、実質的に希土類酸化物を含まぬ粒子上にRhを
分散させた触媒が開示されている。2. Description of the Related Art As an exhaust gas purification catalyst for automobiles, a catalyst that simultaneously oxidizes carbon monoxide (CO) and hydrocarbons (HC) and reduces nitrogen oxides (NOx) has been widely used. Basically, such a catalyst is obtained by applying a γ-alumina slurry to a refractory carrier such as cordierite and calcining, and then supporting a metal such as Pd, Pt, Rh or a mixture thereof. Also, many proposals have been made to enhance the catalytic activity. For example, Japanese Patent Application Laid-Open No. 11147/1986 discloses that γ stabilized with rare earth oxides is used.
-Disclosed is a type of catalyst in which a noble metal or the like is dispersed on alumina particles, in which Rh is dispersed on particles substantially containing no rare earth oxide.
ところで前記のような触媒は、エンジンの設定空燃比
によって浄化特性が大きく左右され、希薄混合気つまり
空燃比が大きいリーン側では燃焼後も酸素（O2）の量が
多くなり、酸化作用が活発に、還元作用が不活発にな
る。この逆に、空燃比の小さいリッチ側では酸化作用が
不活発に、還元作用が活発になる。この酸化と還元のバ
ランスがとれる理論空燃比（A/F＝14.6）付近で触媒は
最も有効に働く。By the way, in such a catalyst, the purification characteristics are greatly affected by the set air-fuel ratio of the engine, and the amount of oxygen (O 2 ) increases after combustion on the lean side, that is, on the lean side where the air-fuel ratio is large, and the oxidizing action becomes active. In addition, the reducing action becomes inactive. Conversely, on the rich side where the air-fuel ratio is small, the oxidizing action is inactive and the reducing action is active. The catalyst works most effectively in the vicinity of the stoichiometric air-fuel ratio (A / F = 14.6) where the balance between the oxidation and the reduction can be achieved.
従って触媒を用いる排気浄化装置を取付けた自動車で
は、排気系の酸素濃度を検出して、混合気を理論空燃比
付近に保つようフィードバック制御が行なわれている。Therefore, in an automobile equipped with an exhaust purification device using a catalyst, feedback control is performed so as to detect the oxygen concentration in the exhaust system and maintain the air-fuel mixture near the stoichiometric air-fuel ratio.
一方、自動車においては低燃費化も要請されており、
そのためには通常走行時なるべく酸素過剰の混合気を燃
焼させればよいことが知られている。しかしそうすると
空燃比がリーン側の酸素過剰雰囲気となって、排気中の
有害成分のうちHC,COは酸化除去できても、NOxは触媒床
に吸着したO2によって活性金属との接触が妨げられるた
めに、還元除去することが困難となる。このため例えば
リーンバーンエンジンの排気系に用いる排気浄化用触媒
としては、Cuなどの遷移金属をゼオライトにイオン交換
担持した遷移金属／ゼオライト触媒が提案されている。On the other hand, automobiles are also required to have low fuel consumption,
It is known that, for that purpose, it is only necessary to burn an air-fuel mixture in excess of oxygen during normal running. However Then the air-fuel ratio becomes an oxygen-excess atmosphere leaner, HC of the harmful components in the exhaust, CO can be be removed oxide, NOx is prevented contact between the active metal by O 2 adsorbed on the catalyst bed Therefore, it is difficult to reduce and remove it. For this reason, for example, as an exhaust purification catalyst used in an exhaust system of a lean burn engine, a transition metal / zeolite catalyst in which a transition metal such as Cu is ion-exchanged and supported on zeolite has been proposed.
ゼオライトは周知のように一般式： xM2/n・Al2O3・ySiO2 で表わされる結晶性アルミノケイ酸で、Ｍ（ｎ価の金
属）,x,yの違いによって、結晶構造中のトンネル構造
（細孔径）が異なり、多くの種類のものが市販されてい
る。又、Si4+の一部をAl3+で置換しているため正電荷が
不足し、その不足を補うためNa+,K+等の陽イオンを結晶
内に保持する性質があるため、高い陽イオン交換能を持
っている。As is well known, zeolite is a crystalline aluminosilicate represented by a general formula: xM 2 / n · Al 2 O 3 · ySiO 2 , and a tunnel in a crystal structure is caused by a difference in M (n-valent metal), x and y. Many types are commercially available, differing in structure (pore diameter). In addition, since a part of Si 4+ is substituted with Al 3+ , the positive charge is insufficient, and there is a property of retaining cations such as Na + , K + in the crystal to compensate for the shortage, so that it is high. Has cation exchange capacity.
特開昭60−125250号公報には、所定の粉末Ｘ線回析に
おける格子面間隔（ｄ値）を持ち、そのSiO2/Al2O3モル
比が20〜100の結晶性アルミノケイ酸塩に銅イオンを含
有させた窒素酸化物接触分解触媒及びその使用方法が開
示されている。JP-A-60-125250 discloses a crystalline aluminosilicate having a lattice spacing (d value) in a predetermined powder X-ray diffraction and having a SiO 2 / Al 2 O 3 molar ratio of 20 to 100. A nitrogen oxide catalytic cracking catalyst containing copper ions and a method of using the same are disclosed.
又、本出願人は特願昭62−291258号において、遷移金
属でイオン交換されたゼオライトが耐火性担体上に担持
されていることを特徴とする排気浄化用触媒を提案し
た。Further, the present applicant has proposed in Japanese Patent Application No. 62-291258 an exhaust purification catalyst characterized in that zeolite ion-exchanged with a transition metal is supported on a refractory carrier.
上記の遷移金属としては、Cu,Co,Cr,Ni,Fe,Mnが好ま
しく、特にCuが好ましい。As the above transition metal, Cu, Co, Cr, Ni, Fe, and Mn are preferable, and Cu is particularly preferable.
ゼオライトは別名分子篩いと言われているように分子
の大きさと並ぶ数Å単位の細孔を有している。そのため
HCが細孔に選択的に取り込まれる。細孔中にはイオン交
換により導入された遷移金属の活性サイトが存在するた
め、そこにHCが吸着しNOxと反応を起こす。このため、
リーン側においてもNOxを効率よく除去することができ
る。Zeolites have pores of several Å units, which are in line with the size of molecules, as they are also called molecular sieves. for that reason
HC is selectively taken into the pores. Since the active site of the transition metal introduced by ion exchange exists in the pores, HC is adsorbed there and reacts with NOx. For this reason,
NOx can also be efficiently removed on the lean side.
しかしながら、ゼオライトには構造の異なる種々のも
のがあり、又、同一種類のゼオライト上にも種々の配位
点が存在する。それ故、ゼオライトにイオン交換担持さ
せる遷移金属として最も好ましいCuを選んだ場合におい
ても、ゼオライトの種類やその配位点によって、得られ
る排気浄化用触媒の性能が異なる。然して、従来のゼオ
ライト系排気浄化用触媒は活性点の性質について充分考
慮することなくゼオライトに遷移金属をイオン交換担持
させたものであったので、触媒の性能を充分に引き出し
たものではなかった。However, there are various types of zeolites having different structures, and various coordination points exist on the same type of zeolite. Therefore, even when Cu, which is the most preferable transition metal to be ion-exchange-supported on zeolite, is selected, the performance of the obtained exhaust purification catalyst differs depending on the type of zeolite and its coordination point. However, the conventional zeolite-based exhaust gas purifying catalyst has a structure in which the transition metal is ion-exchanged and supported on the zeolite without sufficiently considering the nature of the active site, so that the performance of the catalyst is not sufficiently brought out.
本出願人は前記問題点を解決するため特願昭63−9502
6号において、銅でイオン交換されたゼオライトが耐火
性担体上に担持されている排気浄化用触媒において、イ
オン交換点がゼオライトのスパーケージ表面に存在し、
銅イオンに対する酸素原子の配座が４配位正方型である
ことを特徴とする排気浄化用触媒を提案した。The present applicant has filed Japanese Patent Application No. 63-9502 for solving the above-mentioned problems.
In No. 6, in an exhaust purification catalyst in which zeolite ion-exchanged with copper is supported on a refractory carrier, an ion-exchange point is present on the surface of the zeolite spargage,
The present invention has proposed an exhaust purification catalyst characterized in that the conformation of oxygen atoms to copper ions is a tetracoordinate tetragonal type.
ところが、前記のような各々のゼオライト触媒（リー
ンNOx触媒）は高温例えば650℃以上で長期間使用すると
ゼオライトが表面破壊を起すことが判った。このような
表面破壊は、まずゼオライト表面が層状に剥離し、次い
で更に針状の細片に分解してしまう。具体的には、例え
ば750℃で５時間空気中に放置したゼオライト触媒の大
きさ1.5μｍ程度の結晶を電子顕微鏡で観察すると、直
径約20nmの針状の剥離したゼオライト細片が認められ
た。それ故、従来のリーンNOx触媒は、長期間使用する
とNOx浄化率が低下し易く、又、NOx浄化率自体も更に一
層の向上が望まれていた。However, it has been found that each of the above-mentioned zeolite catalysts (lean NOx catalyst) causes surface destruction when used at a high temperature, for example, 650 ° C. or more for a long time. Such surface destruction first delaminates the zeolite surface and then breaks it down further into acicular strips. Specifically, for example, when the zeolite catalyst left in the air at 750 ° C. for 5 hours and observed to have a size of about 1.5 μm was observed with an electron microscope, needle-like exfoliated zeolite fragments having a diameter of about 20 nm were observed. Therefore, in the conventional lean NOx catalyst, when used for a long time, the NOx purification rate tends to decrease, and further improvement of the NOx purification rate itself has been desired.
本発明は前記従来技術における問題点を解決するため
のものである。すなわち、本発明の目的はNOx浄化率が
高く、又、耐久性に優れた排気浄化用触媒を提供するこ
とにある。The present invention is to solve the above-mentioned problems in the prior art. That is, an object of the present invention is to provide an exhaust gas purification catalyst having a high NOx purification rate and excellent durability.
本発明の排気浄化用触媒は、触媒成分がイオン交換及
び／又は担持されたゼオライトが耐火性担体上に担持さ
れている排気浄化用触媒において、ゼオライトは結晶軸
のＣ軸方向に沿って結晶を成長させたZSM−５であるこ
とを特徴とする。The exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst in which a zeolite in which a catalyst component is ion-exchanged and / or supported is supported on a refractory carrier, wherein the zeolite forms crystals along a C-axis direction of a crystal axis. It is a grown ZSM-5.
第３図は本発明の触媒において使用するZSM−５の柱
状結晶の大きさを説明するための図である。図から明ら
かな如く、ａ軸及びｂ軸に比べてＣ軸が長い。又、下記
第１表にZSM−５の性状を示す。FIG. 3 is a diagram for explaining the size of columnar crystals of ZSM-5 used in the catalyst of the present invention. As is clear from the figure, the C axis is longer than the a axis and the b axis. Table 1 below shows the properties of ZSM-5.
ZSM−５はその他の本発明の触媒に適さないゼオライ
トと比較して、SiO2/Al2O3比が大きく酸強度が高い；酸
素10員環である；結晶水が非常に少なく疎水性で弱酸点
が少ない等の特徴を有する。 ZSM-5 has a higher SiO 2 / Al 2 O 3 ratio and higher acid strength than other zeolites which are not suitable for the catalyst of the present invention; it is a 10-membered oxygen ring; It has features such as few weak acid sites.
ZSM−５結晶は異方性があり、第４図（ａ）及び
（ｂ）に示すように（010）面及び（100）面にはスパー
ケージ１が開口している。そして第５図（ａ）に示す結
晶骨格の構成単位が第５図（ｂ）に示すように螺線状に
Ｃ軸方向に伸び、第４図（ａ）の（010）面ではすべて
同じ方向に回ったものが上下にずれて結合し、又、第４
図（ｂ）の（100）面では回る方向が互いに逆のものが
交互に並んで結合してスパーケージ１を形成している。
ところが第６図（ａ）及び（ｂ）に一点鎖線で示すよう
に、スパーケージ１の上下方向（Ｃ軸方向）に存在する
結合の数は各々６個で他の部分に比べて少ない。このた
め第６図（ａ）の（010）面ではａ軸方向に、又第６図
（ｂ）の（100）面ではｂ軸方向に引張力が加わると一
点鎖線に沿って簡単に結晶格子が破壊されることが予想
される。しかも、（100）面では不安定な酸素４員環２
があり、ｂ軸方向への引張には結晶は最も弱いことが予
想される。The ZSM-5 crystal has anisotropy, and as shown in FIGS. 4 (a) and 4 (b), the spar cage 1 is open on the (010) plane and the (100) plane. The structural units of the crystal skeleton shown in FIG. 5 (a) extend spirally in the C-axis direction as shown in FIG. 5 (b), and all the same directions are present in the (010) plane of FIG. 4 (a). Is turned up and down and joined together.
In the (100) plane of FIG. 2B, the spur cages 1 are formed by alternately connecting the rotating directions opposite to each other.
However, as shown by the alternate long and short dash line in FIGS. 6 (a) and 6 (b), the number of bonds existing in the vertical direction (C-axis direction) of the spar cage 1 is six each, which is smaller than the other parts. Therefore, when a tensile force is applied in the a-axis direction on the (010) plane in FIG. 6A and in the b-axis direction on the (100) plane in FIG. 6B, the crystal lattice can be easily formed along the dashed line. Is expected to be destroyed. Moreover, the four-membered oxygen ring 2 is unstable on the (100) plane.
The crystal is expected to be weakest in tension in the b-axis direction.
すなわち、前記の破壊を防ぐ対策として結晶をＣ軸方
向に長くして、Ｃ軸に沿った結合の数を増加すればａ軸
及びｂ軸方向への引張に対して強くなると考えられる。In other words, it is considered that if the crystal is lengthened in the C-axis direction and the number of bonds along the C-axis is increased as a measure to prevent the above-described fracture, the crystal is more resistant to tension in the a-axis and b-axis directions.
結晶軸のＣ軸方向に沿って結晶を成長させたZSM−５
は文献例えばZ.GABELICA etal.,“Zeolites Synthesi
s,structure,Technology and Application",P.55〜63
（1985）に記載された方法により製造してよい。この場
合、結晶軸のａ軸、ｂ軸及びｃ軸の各々の長さの比率は
本発明の目的を達成できる範囲内で適宜選択する。ZSM-5 with crystal grown along the C axis direction of the crystal axis
Is described in the literature such as Z. GABELICA et al., “Zeolites Synthesi
s, structure, Technology and Application ", P.55-63
(1985). In this case, the ratio of the length of each of the a-axis, b-axis, and c-axis of the crystal axis is appropriately selected within a range in which the object of the present invention can be achieved.
本発明の触媒において使用するZSM−５の粒子形状は
針状又は柱状である。ZSM−５を触媒化するためには、
例えば浸漬法を用いてZSM−５粒子に触媒成分をイオン
交換及び／又は担持する。The particle shape of ZSM-5 used in the catalyst of the present invention is acicular or columnar. To catalyze ZSM-5,
For example, the catalyst component is ion-exchanged and / or supported on the ZSM-5 particles using a dipping method.
触媒成分は遷移金属、例えばCu,CO,Cr,Ni,Fe,Mn等の
卑金属又は例えばPt,Rh,Ir,Pd等の貴金属であってよ
い。これらは単独又は組合せて使用することができ、更
に他の助触媒成分を添加してもよい。The catalyst component may be a transition metal, for example a base metal such as Cu, CO, Cr, Ni, Fe, Mn, or a noble metal such as, for example, Pt, Rh, Ir, Pd. These can be used alone or in combination, and other co-catalyst components may be added.
触媒成分としてはCuが好ましく、又、調製条件を適切
に選ぶことにより、イオン交換をZSM−５のスパーケー
ジ表面に存在せしめ、且つ銅イオンに対する酸素原子の
配座を４配位正方型とするとNOx浄化性能の点で好まし
い。As a catalyst component, Cu is preferable, and by appropriately selecting the preparation conditions, ion exchange can be made to occur on the surface of the ZSM-5 spargage, and the conformation of the oxygen atom to the copper ion is a tetracoordinate square type. It is preferable in terms of NOx purification performance.
耐火性担体はセラミック担体又はメタル担体であって
よい。又、担体の種類はモノリス型又はペレット型を使
用できるがモノリス型が好ましい。耐火性担体の寸法や
形状は適宜選択する。The refractory carrier can be a ceramic or metal carrier. As the type of the carrier, a monolith type or a pellet type can be used, but a monolith type is preferable. The size and shape of the refractory carrier are appropriately selected.
耐火性担体へのZSM−５の担持量及びZSM−５への触媒
成分のイオン交換量及び／又は担持量は所望の性能が得
られるように決定する。The amount of ZSM-5 supported on the refractory support and the amount of ion exchange and / or the amount of catalyst component supported on ZSM-5 are determined so as to obtain desired performance.
ZSM−５を結晶をＣ軸方向に沿って成長させることに
より、スパーケージのＣ軸方向に存在する結合の数を増
加させ、ZSM−５の結晶のａ軸及びｂ軸方向への引張強
さを向上させる。By growing the crystal along the C-axis direction of ZSM-5, the number of bonds existing in the C-axis direction of the sparge is increased, and the tensile strength of the ZSM-5 crystal in the a-axis and b-axis directions is increased. Improve.
以下の実施例及び比較例において本発明を更に詳細に
説明する。なお、本発明は下記実施例に限定されるもの
ではない。The present invention will be described in more detail in the following Examples and Comparative Examples. Note that the present invention is not limited to the following examples.
公知方法により、シリカ／アルミナ比が約50でＣ軸方
向長さが約２μｍと約10μｍのZSM−５の結晶（ａ軸及
びｂ軸方向長さは共に約２μｍ）を各々製造し（結晶化
度約90％）、それらを空気中で950℃で５時間加熱した
後、結晶化度を測定した。結果を第１図に示す。Ｃ軸方
向長さが約２μｍのZSM−５の結晶では結晶が破壊さ
れ、結晶化度が約60％であるのに対して、Ｃ軸方向長さ
が約10μｍのZSM−５の結晶では結晶化度が約90％では
ほとんど不変である。According to a known method, ZSM-5 crystals having a silica / alumina ratio of about 50 and a length in the C-axis direction of about 2 μm and a length of about 10 μm (both in both the a-axis direction and the b-axis direction are about 2 μm) are produced (crystallization). After heating them at 950 ° C. for 5 hours in air, the crystallinity was measured. The results are shown in FIG. In a ZSM-5 crystal having a length in the C-axis direction of about 2 μm, the crystal is broken and the crystallinity is about 60%, whereas in a crystal of ZSM-5 having a length in the C-axis direction of about 10 μm, the crystal is broken. It is almost unchanged at about 90%.
又、前記のＣ軸方向長さが約２μｍと約10μｍの２種
の銅をイオン交換法により担持したZSM−５を、コージ
ェライト製モノリス担体（0.7，直径101mm,高さ87mm,
400セル／インチ）に約100g/塗布した。これを容器に
収納し、エンジンの排気系に連設して所定条件下で耐久
試験を行った。第２図にその結果を示す。第２図から明
らかな如く、Ｃ軸方向長さが約10μｍのZSM−５を使用
した本発明の排気浄化用触媒は比較例の排気浄化用触媒
に比べて初期活性が高く、耐久性が大巾に向上した。In addition, ZSM-5 supporting two types of copper having a length in the C-axis direction of about 2 μm and about 10 μm by an ion exchange method was loaded on a cordierite monolithic carrier (0.7, diameter 101 mm, height 87 mm,
400 cells / inch) at about 100 g / coating. This was housed in a container, connected to the exhaust system of the engine, and subjected to a durability test under predetermined conditions. FIG. 2 shows the results. As apparent from FIG. 2, the exhaust purification catalyst of the present invention using ZSM-5 having a length in the C-axis direction of about 10 μm has higher initial activity and higher durability than the exhaust purification catalyst of the comparative example. Improved width.
上述の如く、本発明の排気浄化用触媒は結晶軸のＣ軸
方向に沿って結晶を成長させたZSM−５を使用するた
め、スパーケージのＣ軸方向に存在する結合の数が増加
し、ZSM−５の結晶のａ軸及びｂ軸方向への引張強さが
向上する。このため、高温で長時間使用した場合でも従
来のようなゼオライトの表面破壊が起らず、耐久性が向
上した。又、ZSM−５の結晶が針状又は柱状で長いた
め、耐火性担体に担持した場合、各結晶粒子同士があま
り密着せず、結晶の接点が従来に比べて相対的に少なく
なるので通気性が向上し且つ有効表面積が増大し、触媒
活性も向上した。As described above, since the exhaust gas purifying catalyst of the present invention uses ZSM-5 in which crystals are grown along the C-axis direction of the crystal axis, the number of bonds existing in the C-axis direction of the sparge increases, The tensile strength of the ZSM-5 crystal in the a-axis and b-axis directions is improved. Therefore, even when used at a high temperature for a long time, the surface of the zeolite does not break as in the conventional case, and the durability is improved. In addition, since the crystal of ZSM-5 has a needle-like or columnar shape and is long, when it is supported on a refractory carrier, each crystal particle does not adhere to each other much, and the number of contacts of the crystal becomes relatively small as compared with the conventional one. And the effective surface area increased, and the catalytic activity also improved.
第１図はZSM−５のＣ軸方向長さと、加熱後の結晶度と
の関係を示す図、 第２図は本発明及び比較例の排気浄化用触媒の耐久試験
結果を示す図、 第３図は本発明の触媒において使用するZSM−５の柱状
結晶の大きさを説明するための図、 第４図（ａ）及び（ｂ）はZSM−５結晶の骨格構造を示
す図。 第５図（ａ）及び（ｂ）はZSM−５結晶骨格の構成単位
を示す図、 第６図（ａ）及び（ｂ）はZSM−５結晶骨格の構造破壊
の進行し易い部分を示す図である。 図中、 １……スパーケージ、２……酸素４員環FIG. 1 is a view showing the relationship between the C-axis length of ZSM-5 and the crystallinity after heating, FIG. 2 is a view showing endurance test results of the exhaust gas purifying catalysts of the present invention and a comparative example, FIGS. 4A and 4B are diagrams for explaining the size of columnar crystals of ZSM-5 used in the catalyst of the present invention, and FIGS. 4A and 4B are diagrams showing a skeleton structure of ZSM-5 crystals. FIGS. 5 (a) and 5 (b) show the structural units of the ZSM-5 crystal skeleton, and FIGS. 6 (a) and 6 (b) show the parts of the ZSM-5 crystal skeleton in which the structural destruction easily progresses. It is. In the figure, 1 ... sparge, 2 ... 4-membered oxygen ring
フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) B01J 29/40Continuation of front page (58) Field surveyed (Int.Cl. 6 , DB name) B01J 29/40
Claims (1)
たゼオライトが耐火性担体上に担持されている排気浄化
用触媒において、ゼオライトは結晶軸のＣ軸方向に沿っ
て結晶を成長させたZSM−５であることを特徴とする排
気浄化用触媒。1. An exhaust purification catalyst in which a zeolite in which a catalyst component is ion-exchanged and / or supported is supported on a refractory carrier, the zeolite is a ZSM in which crystals are grown along a C-axis direction of a crystal axis. An exhaust gas purifying catalyst, which is -5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1083685A JP2769515B2 (en) | 1989-03-31 | 1989-03-31 | Exhaust gas purification catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1083685A JP2769515B2 (en) | 1989-03-31 | 1989-03-31 | Exhaust gas purification catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02261546A JPH02261546A (en) | 1990-10-24 |
| JP2769515B2 true JP2769515B2 (en) | 1998-06-25 |
Family
ID=13809348
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1083685A Expired - Fee Related JP2769515B2 (en) | 1989-03-31 | 1989-03-31 | Exhaust gas purification catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2769515B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6869573B2 (en) * | 1990-11-09 | 2005-03-22 | Ngk Insulators, Ltd. | Heater and catalytic converter |
| JP5031168B2 (en) | 2002-08-22 | 2012-09-19 | 株式会社デンソー | Catalyst body |
| EP2931423B1 (en) * | 2012-12-12 | 2021-10-27 | BASF Corporation | Method of making a catalytic article using large particle molecular sieves |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2625919B1 (en) * | 1988-01-19 | 1994-02-11 | Institut Francais Petrole | PROCESS AND CATALYST FOR SELECTIVE REDUCTION OF NITROGEN OXIDES |
-
1989
- 1989-03-31 JP JP1083685A patent/JP2769515B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02261546A (en) | 1990-10-24 |
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