JP2011104485A - Catalyst for purifying exhaust gas - Google Patents

Catalyst for purifying exhaust gas Download PDF

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JP2011104485A
JP2011104485A JP2009260298A JP2009260298A JP2011104485A JP 2011104485 A JP2011104485 A JP 2011104485A JP 2009260298 A JP2009260298 A JP 2009260298A JP 2009260298 A JP2009260298 A JP 2009260298A JP 2011104485 A JP2011104485 A JP 2011104485A
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catalyst
exhaust gas
oxide material
phosphorus
surface area
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JP5504834B2 (en
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Hisashi Kuno
央志 久野
Masahide Miura
真秀 三浦
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Toyota Motor Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for purifying an exhaust gas capable of controlling the phosphorus poisoning of a catalyst coating layer, applied to an engine driven in the presence of a phosphorus, to a fully satisfactory level. <P>SOLUTION: The catalyst for purifying an exhaust gas, in which the surface of the catalyst coating layer of a ternary catalyst is coated with an oxide material, has a specific surface area of the oxide material of 9 m<SP>2</SP>/g or less and a coating amount from 10 to 40 g/L. In addition, the catalyst contains at least one of ceria, zirconia, and alumina. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、排ガス浄化用触媒に関し、さらに詳しくは三元触媒の触媒コート層表面に酸化物材料をコートした排ガス浄化用触媒であって酸化物材料の比表面積およびコート量を特定の範囲にすることによって触媒コート層のリン被毒を回避乃至は抑制し得る排ガス浄化用触媒に関するものである。   The present invention relates to an exhaust gas purification catalyst, and more particularly, an exhaust gas purification catalyst in which an oxide material is coated on the surface of a catalyst coat layer of a three-way catalyst, and the specific surface area and the coating amount of the oxide material are in a specific range. The present invention relates to an exhaust gas purifying catalyst capable of avoiding or suppressing phosphorus poisoning of a catalyst coat layer.

自動車等の内燃機関から排出される排ガス中には炭化水素(HC)、一酸化炭素(CO)及び酸化窒素(NO)が含まれている。これらの物質は、各国で強化されている排ガス規制を満たし且つ埋蔵量が少なく資源リスクの高い貴金属の使用を最小限に抑えことを目的に開発された排ガス浄化用触媒によって浄化されてから大気中に放出されている。ガソリンエンジン用触媒の代表的なものとしては、アルミナ(Al)、シリカ(SiO)、ジルコニア(ZrO)、チタニア(TiO)などの多孔質酸化物担体に、貴金属の中でも白金(Pt)、パラジウム(Pd)、ロジウム(Rh)などを主たる活性種として胆持した三元触媒が広く用いられている。 The exhaust gas discharged from an internal combustion engine such as an automobile contains hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxide (NO x ). These substances are exhausted into the atmosphere after being purified by an exhaust gas purifying catalyst that has been developed with the aim of minimizing the use of precious metals with low reserves and high resource risks that meet the strict exhaust gas regulations in each country. Has been released. Typical gasoline engine catalysts include porous oxide carriers such as alumina (Al 2 O 3 ), silica (SiO 2 ), zirconia (ZrO 2 ), titania (TiO 2 ), platinum among noble metals. A three-way catalyst having a main active species of (Pt), palladium (Pd), rhodium (Rh) and the like is widely used.

この三元触媒は、排ガス中のHC及びCOを酸化して浄化するとともに、HC及びCOを還元種としてNOを還元して浄化するものであり、前記の貴金属が最も高活性に作用し得てHC、COおよびNOが均一に浄化できるように触媒中を理論空燃比近傍に保つ酸化セリウムを主成分とする酸素吸蔵材(OSC材)が含まれている。
一方、触媒を使用するにあたり、触媒被毒は避けられない課題である。被毒は、主にガソリンなどの燃料中に含まれる硫黄分によるものと、エンジンオイル中に含まれるジアルキルジチオリン酸亜鉛(ZDDPと略記される)によるもの、そしてオクタン価向上剤としてガソリン中に添加されるメチルシクロペンタジエニルマンガントリカルボニル(MMTと略記される)によるものが挙げられる。
This three-way catalyst oxidizes and purifies HC and CO in exhaust gas, and reduces and purifies NO X using HC and CO as reducing species, and the above-mentioned noble metals can act most highly. Te HC, the oxygen storage material composed mainly of cerium oxide to keep the catalyst in near stoichiometric air-fuel ratio so that it can purify CO and NO X are uniformly (OSC material) is included.
On the other hand, when a catalyst is used, catalyst poisoning is an unavoidable problem. Poisoning is mainly caused by sulfur contained in fuels such as gasoline, zinc dialkyldithiophosphate (abbreviated as ZDDP) contained in engine oil, and added to gasoline as an octane improver. And methylcyclopentadienyl manganese tricarbonyl (abbreviated as MMT).

これらの被毒のうち、硫黄分による被毒物質は、エンジンの空燃比制御や温度制御によりSO若しくはHSとして気化させて脱離させることも可能であるが、リン(P)およびMnを含む被毒物質は、触媒コート層に付着しガラス質を形成して蓄積するため被毒からの回復は困難となる。
このため、触媒のリンによる被毒を抑制する技術が提案されており、その1つに触媒中にリンと反応しやすい物質を添加する方法が提案されたが、リン付着量が飽和になると触媒層への被毒が始まるため、さらなる解決策が求められている。
Among these poisons, poisonous substances due to sulfur can be vaporized as SO 2 or H 2 S by the air-fuel ratio control or temperature control of the engine and desorbed, but phosphorus (P) and Mn Since the poisoning substance containing, which adheres to the catalyst coat layer and forms a glassy substance, it is difficult to recover from poisoning.
For this reason, a technique for suppressing poisoning of the catalyst by phosphorus has been proposed, and a method for adding a substance that easily reacts with phosphorus into the catalyst has been proposed. As the poisoning of the layers begins, further solutions are needed.

その1つとして、特許文献1には、担体上に貴金属触媒成分を被覆した排ガス浄化用触媒において、触媒表面にTiOを被覆したP被毒防止処理を施した排ガス浄化用触媒が記載されている。しかし、特許文献1には、排ガス浄化用触媒による浄化作用を定性的に示されているに過ぎず、具体例では排ガス浄化用触媒で一般的に使用されるOSC材を用いていないため、OSC材中に含まれる酸化セリウム(セリア)がTiOと反応しやすく却って酸素吸蔵量を低下させて触媒性能に悪影響を及ぼすとの認識はない。 As one of them, Patent Document 1 describes an exhaust gas purification catalyst in which a noble metal catalyst component is coated on a carrier, and an exhaust gas purification catalyst having a catalyst surface coated with TiO 2 and subjected to P poisoning prevention treatment. Yes. However, Patent Document 1 only qualitatively shows the purifying action by the exhaust gas purifying catalyst, and the specific example does not use the OSC material generally used in the exhaust gas purifying catalyst. There is no recognition that cerium oxide (ceria) contained in the material is likely to react with TiO 2 , thereby reducing the oxygen storage amount and adversely affecting the catalyst performance.

特許文献2には、ハニカム形状の担体基材と、該担体基材のセル壁表面に形成された触媒金属を担持した第1コート層と、該第1コート層の表面に形成された触媒金属を担持しない第2コート層とよりなり、該第1コート層の層厚を該第1コート層と該第2コート層の合計層厚の1/10〜1/5としたディーゼル排ガス浄化用触媒が記載されている。そして、具体例として650℃で50時間の耐久試験後でHC浄化率が75〜80%の浄化活性を示す排ガス浄化用触媒が示されている。しかし、特許文献2にはリンによる被毒について記載されてなく、被毒物質がガラス質化して蓄積し得る厳しい条件、すなわちリンを含む運転条件でより高温そして長時間の耐久試験後でも触媒が同様の浄化活性を示すか不明である。   Patent Document 2 discloses a honeycomb-shaped carrier substrate, a first coat layer carrying a catalyst metal formed on the cell wall surface of the carrier substrate, and a catalyst metal formed on the surface of the first coat layer. A diesel exhaust gas purification catalyst comprising: a second coat layer that does not support the first coating layer, wherein the thickness of the first coating layer is 1/10 to 1/5 of the total thickness of the first coating layer and the second coating layer Is described. As a specific example, an exhaust gas purifying catalyst showing a purifying activity with an HC purification rate of 75 to 80% after an endurance test at 650 ° C. for 50 hours is shown. However, Patent Document 2 does not describe the poisoning by phosphorus, and the catalyst can be used even under severe conditions where poisonous substances can vitrify and accumulate, that is, operating conditions including phosphorus, even at higher temperatures and for a long time. It is unknown whether the same purification activity is exhibited.

さらに、特許文献3には、オイル及び/又は燃料に由来する添加剤による毒に対して優れた耐性を有する自動車排ガス処理触媒であって、排ガスと最初に接触する上流端を有する基材、例えばハニカム基材、貴金属を全くか少ししか含まない耐熱性金属酸化物および場合により希土類酸化物からなるベースコート、高濃度の貴金属を含む貴金属含有第1触媒層および上流端から0.5〜5cm又は3〜70%の長さを有する毒捕捉領域を有する自動車排ガス処理触媒が記載されている。しかし、特許文献3に記載の自動車排ガス処理触媒によれば、触媒層の表面は毒捕捉領域によって全く保護されないため毒補足領域の性質によっては三元触媒の性能が著しく低下し得る。   Further, Patent Document 3 discloses an automobile exhaust gas treatment catalyst having excellent resistance to poisons caused by additives derived from oil and / or fuel, and a base material having an upstream end that first comes into contact with exhaust gas, for example, Honeycomb substrate, base coat consisting of refractory metal oxide and optionally rare earth oxide with little or no noble metal, first catalyst layer containing noble metal with high concentration of noble metal and 0.5-5 cm or 3 from upstream end An automobile exhaust gas treatment catalyst having a poison capture zone having a length of ˜70% is described. However, according to the automobile exhaust gas treatment catalyst described in Patent Document 3, the surface of the catalyst layer is not protected at all by the poison trapping region, so that the performance of the three-way catalyst can be remarkably lowered depending on the nature of the poison capturing region.

特開昭53−167046号公報Japanese Patent Laid-Open No. 53-167046 特開平10−225635号公報JP-A-10-225635 特表2009−501079号公報Special table 2009-501079 gazette

このように、従来公知の技術によっては、リンの存在下に運転されるエンジンに適用される触媒コート層のリン被毒を充分満足のいくレベルまで抑制することができない。
従って、本発明の目的は、リンの存在下に運転されるエンジンに適用される触媒コート層のリン被毒を充分満足のいくレベルまで抑制し得る排ガス浄化用触媒を提供することである。
As described above, it is impossible to suppress phosphor poisoning of the catalyst coat layer applied to the engine operated in the presence of phosphorus to a sufficiently satisfactory level by a conventionally known technique.
Accordingly, an object of the present invention is to provide an exhaust gas purifying catalyst capable of suppressing phosphorus poisoning of a catalyst coat layer applied to an engine operated in the presence of phosphorus to a sufficiently satisfactory level.

本発明は、三元触媒の触媒コート層表面に酸化物材料をコートした排ガス浄化用触媒であって、前記酸化物材料の比表面積が9m/g以下で且つコート量が10g/L以上40g/L以下であることを特徴とする排ガス浄化用触媒に関する。
本願発明における酸化物材料の比表面積とは、コートする前の原料として用いる酸化物の比表面積を示す。
また、本明細書において、リン被毒を充分満足のいくレベルまで抑制し得るとは、後述の実施例の欄に詳述される方法で測定したTHC浄化率が75%以上であることを意味する。
The present invention is an exhaust gas purifying catalyst in which an oxide material is coated on the surface of a catalyst coat layer of a three-way catalyst, wherein the oxide material has a specific surface area of 9 m 2 / g or less and a coating amount of 10 g / L or more and 40 g. The present invention relates to an exhaust gas purifying catalyst characterized by being / L or less.
The specific surface area of the oxide material in the present invention refers to the specific surface area of the oxide used as a raw material before coating.
Further, in this specification, being able to suppress phosphorus poisoning to a sufficiently satisfactory level means that the THC purification rate measured by the method described in detail in the Examples section below is 75% or more. To do.

本発明によれば、リンの存在下に運転されるエンジンに適用される触媒コート層のリン被毒を充分満足のいくレベルまで抑制し得る排ガス浄化用触媒が得られる。   According to the present invention, it is possible to obtain an exhaust gas purifying catalyst capable of suppressing phosphorus poisoning of a catalyst coat layer applied to an engine operated in the presence of phosphorus to a sufficiently satisfactory level.

図1は、本発明の排ガス浄化用触媒の一例の模式図である。FIG. 1 is a schematic view of an example of an exhaust gas purifying catalyst of the present invention. 図2は、排ガス浄化用触媒のリン被毒の加速劣化試験(耐久試験)後のリン付着量を観察する方向を示す模式図である。FIG. 2 is a schematic diagram showing the direction of observing the amount of phosphorus adhesion after an accelerated deterioration test (endurance test) of phosphorus poisoning of the exhaust gas purification catalyst. 図3は、排ガス浄化用触媒のリン被毒の加速劣化試験後のリン付着量を観察する触媒の端面の構造を示す模式図である。FIG. 3 is a schematic diagram showing the structure of the end face of the catalyst for observing the amount of phosphorus adhering after the accelerated deterioration test of phosphorus poisoning of the exhaust gas purifying catalyst. 図4は、実施例1で得られた排ガス浄化用触媒のリン被毒の加速劣化試験後の端面でのリン付着量をEPMAで観察した結果を示す写真の写しである。FIG. 4 is a copy of a photograph showing the result of observing the amount of phosphorus adhering on the end surface after the accelerated deterioration test of phosphorus poisoning of the exhaust gas purifying catalyst obtained in Example 1 with EPMA. 図5は、比較例1で得られた排ガス浄化用触媒のリン被毒の加速劣化試験後の端面でのリン付着量をEPMAで観察した結果を示す写真の写しである。FIG. 5 is a copy of a photograph showing the result of observing the amount of phosphorus adhering on the end face after the accelerated deterioration test of phosphorus poisoning of the exhaust gas purifying catalyst obtained in Comparative Example 1 with EPMA. 図6は、排ガス浄化用触媒のリン被毒の加速劣化試験後のリン付着量を観察する触媒の流れ方向で上流から10mm後方の位置の構造を示す模式図である。FIG. 6 is a schematic diagram showing a structure at a position 10 mm behind from the upstream in the flow direction of the catalyst for observing the amount of phosphorus adhesion after an accelerated deterioration test of phosphorus poisoning of the exhaust gas purification catalyst. 図7は、実施例1で得られた排ガス浄化用触媒のリン被毒の加速劣化試験後の流れ方向で上流から10mm後方の位置でのリン付着量を観察した結果を示す写真の写しである。FIG. 7 is a copy of a photograph showing the result of observing the amount of phosphorus adhering at a position 10 mm behind from the upstream in the flow direction after the phosphorous poisoning accelerated deterioration test of the exhaust gas purifying catalyst obtained in Example 1. . 図8は、比較例1で得られた排ガス浄化用触媒のリン被毒の加速劣化試験後の流れ方向で上流から10mm後方の位置でのリン付着量を観察した結果を示す写真の写しである。FIG. 8 is a copy of a photograph showing the result of observing the amount of phosphorus adhering at a position 10 mm behind from the upstream in the flow direction after the phosphorous poisoning accelerated deterioration test of the exhaust gas purifying catalyst obtained in Comparative Example 1. .

本発明によれば、三元触媒の触媒コート層表面に酸化物材料をコートした排ガス浄化用触媒であって、前記酸化物材料の比表面積が9m/g以下、例えば0.2〜9m/gで且つコート量が10g/L以上40g/L以下である排ガス浄化用触媒により、経時劣化を受けることが少なく酸素吸蔵量に悪影響を及ぼさずないため、触媒コート層のリン被毒を回避して良好な浄化性能を得ることが可能となる。 According to the present invention, an exhaust gas-purifying catalyst having an oxide material coated on the surface of a catalyst coat layer of a three-way catalyst, the specific surface area of the oxide material is 9 m 2 / g or less, for example, 0.2 to 9 m 2. / G and a coating amount of 10 g / L or more and 40 g / L or less, the catalyst for the catalyst coating layer avoids phosphorous poisoning because it does not deteriorate with time and does not adversely affect the oxygen storage amount. Thus, it is possible to obtain a good purification performance.

以下、本発明の排ガス浄化用触媒について、図1を用いて説明する。
本発明の排ガス浄化用触媒1は、基材2、例えばハニカム基材と、該基材2にコートした三元触媒の触媒コート層3と、その表面に酸化物材料をコートした酸化物材料コート層4からなり、前記酸化物材料の比表面積が9m/g以下で且つコート量が10g/L以上40g/L以下であることが必要である。
Hereinafter, the exhaust gas purifying catalyst of the present invention will be described with reference to FIG.
The exhaust gas-purifying catalyst 1 of the present invention comprises a substrate 2, for example, a honeycomb substrate, a catalyst coat layer 3 of a three-way catalyst coated on the substrate 2, and an oxide material coat in which an oxide material is coated on the surface. It is required that the oxide material has a specific surface area of 9 m 2 / g or less and a coating amount of 10 g / L or more and 40 g / L or less.

前記のハニカム基材としてはコージェライトなどのセラミックス材料やステンレス鋼などにより形成され得る。また、本発明の排ガス浄化用触媒は任意の形状に成形して用いることができる。
前記の三元触媒成分としては、貴金属および遷移金属のうちの少なくとも1種の金属が挙げられる。貴金属として、Pt、Pd、Rh、Irからなる群から選ばれる少なくとも1種の元素、特にPdおよびRhが挙げられる。三元触媒成分として遷移金属を用いる場合には、例えばNiなどが用いられ得る。
The honeycomb substrate can be formed of a ceramic material such as cordierite or stainless steel. Further, the exhaust gas purifying catalyst of the present invention can be used after being molded into an arbitrary shape.
Examples of the three-way catalyst component include at least one of a noble metal and a transition metal. Examples of the noble metal include at least one element selected from the group consisting of Pt, Pd, Rh, and Ir, particularly Pd and Rh. When a transition metal is used as the three-way catalyst component, for example, Ni can be used.

前記の三元触媒の触媒コート層3は、金属酸化物、例えばセリア−ジルコニア複合酸化物に貴金属触媒、例えばPdおよびRhを担持させた粉末と水とからコート用スラリーを得て、スラリーを基材、例えばハニカム基材に投入し、下部を吸引することによってコートし、乾燥、焼成することによって基材に形成し得る。前記の触媒コート層のコート量はスラリーの粘度や固形分量、スラリー投入量を調整することによって行い得る。   The catalyst coat layer 3 of the three-way catalyst is obtained by obtaining a slurry for coating from a powder in which a metal oxide, for example, a ceria-zirconia composite oxide is loaded with a noble metal catalyst, for example, Pd and Rh, and water. It can be formed into a base material by putting it into a material, for example, a honeycomb base material, coating by sucking the lower part, drying and firing. The coating amount of the catalyst coating layer can be performed by adjusting the viscosity, solid content, and slurry input amount of the slurry.

本発明における触媒コート層にコートする酸化物材料としては、アルミナ、ジルコニア、シリカ、セリアやこれらの少なくとも2種類を組み合わせた複合酸化物が挙げられ、好適にはセリア、ジルコニアおよびアルミナのうちの少なくとも1種類を含むもの、例えばセリア−ジルコニア複合酸化物が挙げられる。また、前記の酸化物材料はさらに1種類以上の希土類元素、例えばセリウム、ランタン、ネオジウム、プラセオジウムを含み得る。これらの希土類元素は酸化物として含有され得る。   Examples of the oxide material to be coated on the catalyst coating layer in the present invention include alumina, zirconia, silica, ceria and a composite oxide in which at least two of these are combined, and preferably at least of ceria, zirconia and alumina. One containing one kind, for example, ceria-zirconia composite oxide can be mentioned. The oxide material may further include one or more rare earth elements such as cerium, lanthanum, neodymium, and praseodymium. These rare earth elements can be contained as oxides.

本発明においては、前記酸化物材料の比表面積およびコート量が重要であり、比表面積は9m/g以下、例えば0.2〜9m/g、その中でも1〜9m/gであることが必要である。また、コート量は10g/L以上40g/L以下、特に10g/L以上30g/L以下であることが必要である。酸化物材料の比表面積が過度に大きいと酸化物材料のリン被毒抑制効果がかえって低く、コート量が前記下限より少ないと酸化物材料のリン被毒抑制効果が低く、コート量が前記上限より多いと三元触媒の性能が低下する。このように、本発明における酸化物材料層は、直接的には排ガスの浄化反応に寄与しないため、リン被毒が抑制される範囲で最小限とすることが望ましい。 It In the present invention, the important specific surface area and coating weight of the oxide material, the specific surface area 9m 2 / g or less, for example 0.2~9m 2 / g, 1~9m 2 / g among them is required. Further, the coating amount needs to be 10 g / L or more and 40 g / L or less, particularly 10 g / L or more and 30 g / L or less. If the specific surface area of the oxide material is excessively large, the phosphorous poisoning suppression effect of the oxide material is rather low. If the coating amount is less than the lower limit, the phosphorous poisoning suppression effect of the oxide material is low, and the coating amount exceeds the upper limit. If the amount is too large, the performance of the three-way catalyst will deteriorate. Thus, since the oxide material layer in the present invention does not directly contribute to the exhaust gas purification reaction, it is desirable to minimize the oxide material layer within a range in which phosphorus poisoning is suppressed.

本発明の排ガス浄化用触媒は、触媒コート層のリン被毒を充分満足のいくレベルまで抑制しえるため、リンの存在下に運転されるエンジンに適用されても安定した排ガス浄化性能を達成することが可能である。   The exhaust gas purifying catalyst of the present invention can suppress phosphorus poisoning of the catalyst coat layer to a sufficiently satisfactory level, and thus achieves stable exhaust gas purifying performance even when applied to an engine operated in the presence of phosphorus. It is possible.

以下、本発明の実施例を示す。
以下の実施例は単に説明するためのものであり、本発明を限定するものではない。
以下の各例で、触媒の物性および浄化性能の評価は以下に示す方法により行った。
Examples of the present invention will be described below.
The following examples are for illustrative purposes only and are not intended to limit the invention.
In each of the following examples, the physical properties and purification performance of the catalyst were evaluated by the following methods.

1.比表面積
BET1点法で吸着質として窒素を用いて常法により測定した。
測定装置:島津製作所 Micromeritics Flowsorb II 2300
2.リンの蓄積状態
触媒の端面、および触媒を分解したときのガス流れ方向での10mm後方の位置で、各々についてEPMA(Electron Probe Micro Micro Analyzer:電子線マイクロアナライザ )を用いてEPMA測定を行い、リンの蓄積状態を確認した。
測定装置:島津製作所 MACHS−200
1. Specific surface area was measured by a conventional method using nitrogen as an adsorbate by the BET one-point method.
Measuring device: Shimadzu Micromeritics Flowsorb II 2300
2. Phosphorus accumulation state EPMA measurement was performed using EPMA (Electron Probe Micro Micro Analyzer) for each of the catalyst end face and the position 10 mm behind in the gas flow direction when the catalyst was decomposed. The accumulation state of was confirmed.
Measuring device: Shimadzu MACHS-200

3.リン被毒耐久試験方法
実施例および比較例で得られた触媒を装着して、一定の条件で走行後にも触媒活性を維持しているか否かを確認するために、実際の自動車エンジンを用いて加速劣化試験(耐久試験)を行った。
装着・走行条件:触媒にセラミックマットを巻き、排気管にキャニングし、ハニカムの中央に熱電対を差し込んだ。この排気管をエンジンにセットし、熱電対の温度が950℃±20℃になるようにエンジン回転数/トルク等を調整した。このとき、A/Fは14と15を一定時間ずつ繰り返すサイクル試験とした。その際に、リン被毒を促進するため、エンジンオイルを10mL/時間ずつ触媒の上流に添加し、耐久試験時間を100時間とした。
3. Phosphorus poisoning endurance test method The actual automobile engine was used to check whether or not the catalyst activity was maintained even after running under certain conditions with the catalysts obtained in the examples and comparative examples. An accelerated deterioration test (endurance test) was conducted.
Installation and running conditions: A ceramic mat was wound around the catalyst, it was canned in the exhaust pipe, and a thermocouple was inserted in the center of the honeycomb. This exhaust pipe was set in the engine, and the engine speed / torque and the like were adjusted so that the temperature of the thermocouple was 950 ° C. ± 20 ° C. At this time, A / F was a cycle test in which 14 and 15 were repeated for a certain time. At that time, in order to promote phosphorus poisoning, engine oil was added to the upstream of the catalyst at 10 mL / hour, and the durability test time was set to 100 hours.

4.触媒の浄化性能試験方法
上記の方法で耐久試験を施した触媒をエンジンに取り付け、触媒前10mmの位置の温度が500℃になるように、エンジン回転数/トルクを調整した。そして、A/Fが14.6になるように調整し、触媒の前後のガス濃度差より、浄化率を下記の計算式から算出し、THC浄化率(%表示)として示す。
THC浄化率=[(触媒の入ガス濃度−触媒の出ガス濃度)/触媒の入りガス濃度] x100
4). Catalyst purification performance test method The catalyst subjected to the durability test by the above method was attached to the engine, and the engine speed / torque was adjusted so that the temperature at a position 10 mm before the catalyst was 500 ° C. And it adjusts so that A / F may be set to 14.6, the purification rate is computed from the following formula from the gas concentration difference before and behind the catalyst, and is shown as the THC purification rate (% display).
THC purification rate = [(catalyst inlet gas concentration−catalyst outlet gas concentration) / catalyst inlet gas concentration] × 100

実施例1
1−1 三元触媒層のコート
希土類元素を含むセリア−ジルコニア複合酸化物(ローディア社製、CeO:50質量%、ZrO:40質量%、Y:5質量%、LaO:5質量%)に硝酸パラジウム薬液および硝酸ロジウム溶液を含浸担持し、希土類元素を含むγ−アルミナ(サソール社製、Al:96質量%、La:4質量%)と4:6の質量比率で混合した。さらに、アルミナバインダーと混合粉末とを1:19の質量比率で混合し、水を加えてコート用スラリーとした。
このスラリーをセラミックハニカム(デンソー社製、セル密度600cell/inch、壁厚3mil、φ103xL105)の上部から投入し、下部を吸引することでコートし、120℃で0.5時間乾燥後、大気中400℃で1時間焼成した。
コート量は、焼成後の質量が180g/Lとなるようにした。
Example 1
1-1 Three-way catalyst layer coating Ceria-zirconia composite oxide containing rare earth elements (Rodia Co., CeO 2 : 50% by mass, ZrO 2 : 40% by mass, Y 2 O 3 : 5% by mass, LaO 3 : 5 mass%) impregnated and supported with a palladium nitrate chemical solution and a rhodium nitrate solution, and containing γ-alumina containing rare earth elements (manufactured by Sasol, Al 2 O 3 : 96 mass%, La 2 O 3 : 4 mass%) and 4: Mixed at a mass ratio of 6. Furthermore, the alumina binder and the mixed powder were mixed at a mass ratio of 1:19, and water was added to form a slurry for coating.
This slurry was applied from the top of a ceramic honeycomb (Denso Corp., cell density 600 cell / inch 2 , wall thickness 3 mil, φ103 × L105), coated by sucking the bottom, dried at 120 ° C. for 0.5 hours, and then in the atmosphere Baked at 400 ° C. for 1 hour.
The coating amount was such that the mass after firing was 180 g / L.

1−2 酸化物材料(被毒抑制層)のコート
比表面積が3m/gのアルミナとアルミナバインダーとを1:19の比率で混合し、水を加えてスラリーとした。このスラリーを、1−1で作製した三元触媒層がコートされたセラミックハニカムの上部より投入し、下部を吸引することで三元触媒層表面に均一にコートし、120℃で0.5時間乾燥後、大気中400℃で1時間焼成した。
得られた排ガス浄化用触媒の被毒抑制層のコート量は、スラリーの粘度や固形分量、スラリー投入量を調整することで、焼成後の質量が10g/Lとなるようにした。
1−3 物性測定および評価
得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:3m/g コート量:10g/L
2)THC浄化率:88%
また、耐久試験後の端面でのリン付着量をEPMAで観察した結果を図4、また流れ方向で上流から10mm後方の位置でのリン付着量を観察した結果を図7に示す。
1-2 Coat of oxide material (poisoning suppression layer) Alumina having a specific surface area of 3 m 2 / g and an alumina binder were mixed at a ratio of 1:19, and water was added to form a slurry. This slurry is introduced from the upper part of the ceramic honeycomb coated with the three-way catalyst layer prepared in 1-1, and the lower part is sucked to uniformly coat the surface of the three-way catalyst layer, at 120 ° C. for 0.5 hour. After drying, it was fired at 400 ° C. for 1 hour in the air.
The coating amount of the poisoning suppression layer of the obtained exhaust gas purifying catalyst was adjusted such that the mass after firing was 10 g / L by adjusting the viscosity, solid content, and slurry input amount of the slurry.
1-3 Measurement of physical properties and evaluation The obtained exhaust gas-purifying catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 Specific surface area: 3 m 2 / g Coating amount: 10 g / L
2) THC purification rate: 88%
Moreover, the result of having observed the phosphorus adhesion amount in the end surface after an endurance test by EPMA is shown in FIG. 4, and the result of observing the phosphorus adhesion amount at a position 10 mm behind from the upstream in the flow direction is shown in FIG.

実施例2
実施例1で用いた比表面積が3m/gのアルミナに代えて、比表面積が2m/gのジルコニアを用いた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:ZrO 比表面積:2m/g コート量:10g/L
2)THC浄化率:83%
Example 2
An exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that zirconia having a specific surface area of 2 m 2 / g was used instead of alumina having a specific surface area of 3 m 2 / g used in Example 1. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: ZrO 2 Specific surface area: 2 m 2 / g Coating amount: 10 g / L
2) THC purification rate: 83%

実施例3
実施例1で用いた比表面積が3m/gのアルミナに代えて、比表面積が1m/gのセリアを用いた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:CeO 比表面積:1m/g コート量:10g/L
2)THC浄化率:87%
Example 3
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that ceria having a specific surface area of 1 m 2 / g was used instead of alumina having a specific surface area of 3 m 2 / g used in Example 1. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: CeO 2 specific surface area: 1 m 2 / g Coating amount: 10 g / L
2) THC purification rate: 87%

実施例4
実施例1で用いた比表面積が3m/gのアルミナに代えて、比表面積が9m/gのセリアージルコニア複合酸化物を用いた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:CeZrO 比表面積:9m/g コート量:10g/L
2)THC浄化率:85%
Example 4
An exhaust gas purifying catalyst was prepared in the same manner as in Example 1 except that ceria-zirconia composite oxide with a specific surface area of 9 m 2 / g was used instead of alumina with a specific surface area of 3 m 2 / g used in Example 1. Obtained. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: CeZrO 4 Specific surface area: 9 m 2 / g Coating amount: 10 g / L
2) THC purification rate: 85%

実施例5
実施例1で用いた比表面積が3m/gのアルミナに代えて、比表面積が8m/gのアルミナを用いた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:8m/g コート量:10g/L
2)THC浄化率:84%
Example 5
An exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that alumina having a specific surface area of 8 m 2 / g was used instead of alumina having a specific surface area of 3 m 2 / g used in Example 1. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 Specific surface area: 8 m 2 / g Coating amount: 10 g / L
2) THC purification rate: 84%

実施例6
コート量を10g/Lから30g/Lに変えた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:3m/g コート量:30g/L
2)THC浄化率:81%
Example 6
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the coating amount was changed from 10 g / L to 30 g / L. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 Specific surface area: 3 m 2 / g Coating amount: 30 g / L
2) THC purification rate: 81%

実施例7
コート量を10g/Lから40g/Lに変えた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:3m/g コート量:40g/L
2)THC浄化率:75%
Example 7
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the coating amount was changed from 10 g / L to 40 g / L. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 Specific surface area: 3 m 2 / g Coating amount: 40 g / L
2) THC purification rate: 75%

比較例1
酸化物材料コート層を形成しなかった他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
なし
2)THC浄化率:72%
また、耐久試験後の端面でのリン付着量をEPMAで観察した結果を図5、また流れ方向で上流から10mm後方の位置でのリン付着量を観察した結果を図8に示す。
Comparative Example 1
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the oxide material coat layer was not formed. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer None 2) THC purification rate: 72%
Moreover, the result of having observed the phosphorus adhesion amount in the end surface after an endurance test by EPMA is shown in FIG. 5, and the result of observing the phosphorus adhesion amount at a position 10 mm behind from the upstream in the flow direction is shown in FIG.

比較例2
実施例1で用いた比表面積が3m/gのアルミナに代えて、比表面積が86m/gのアルミナを用いた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:86m/g コート量:10g/L
2)THC浄化率:63%
Comparative Example 2
An exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that alumina having a specific surface area of 86 m 2 / g was used instead of alumina having a specific surface area of 3 m 2 / g used in Example 1. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 specific surface area: 86 m 2 / g Coating amount: 10 g / L
2) THC purification rate: 63%

比較例3
コート量を10g/Lから60g/Lに変えた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:3m/g コート量:60g/L
2)THC浄化率:56%
Comparative Example 3
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the coating amount was changed from 10 g / L to 60 g / L. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 Specific surface area: 3 m 2 / g Coating amount: 60 g / L
2) THC purification rate: 56%

比較例4
コート量を10g/Lから60g/Lに変えた他は実施例2と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:ZrO 比表面積:3m/g コート量:60g/L
2)THC浄化率:59%
Comparative Example 4
Exhaust gas purification catalyst was obtained in the same manner as in Example 2 except that the coating amount was changed from 10 g / L to 60 g / L. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coat layer Oxide material: ZrO 2 specific surface area: 3 m 2 / g Coat amount: 60 g / L
2) THC purification rate: 59%

比較例4
コート量を10g/Lから2g/Lに変えた他は実施例1と同様にして排ガス浄化用触媒を得た。得られた排ガス浄化用触媒について評価を行った。結果を次に示す。
1)酸化物材料コート層
酸化物材料:Al 比表面積:3m/g コート量:2g/L
2)THC浄化率:70%
Comparative Example 4
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the coating amount was changed from 10 g / L to 2 g / L. The obtained exhaust gas purification catalyst was evaluated. The results are shown below.
1) Oxide material coating layer Oxide material: Al 2 O 3 Specific surface area: 3 m 2 / g Coating amount: 2 g / L
2) THC purification rate: 70%

図4と図5との比較から、色が白い(図中の右のバーの上)方がリンの濃度が高いので触媒の端面においては、実施例1の排ガス浄化用触媒は比較例1の排ガス浄化用触媒に比べてリンの付着が顕著に少ないことが確認された。
また、図7と図8との比較から、流れ方向で上流から10mm後方の位置でも、実施例1の排ガス浄化用触媒は比較例1の排ガス浄化用触媒に比べてリンの付着が顕著に少ないことが確認された。
また、上記のTHC浄化率について各実施例と各比較例との比較から、前記酸化物材料コート層の比表面積が9m/g以下で且つコート量が10g/L以上40g/L以下であることが必要であることが理解された。
From the comparison between FIG. 4 and FIG. 5, the whiter color (above the right bar in the figure) has a higher phosphorus concentration, so that the exhaust gas purifying catalyst of Example 1 is the same as that of Comparative Example 1 at the end face of the catalyst. It was confirmed that the adhesion of phosphorus was significantly less than that of the exhaust gas purification catalyst.
7 and 8, the exhaust gas purification catalyst of Example 1 has significantly less phosphorus adhesion than the exhaust gas purification catalyst of Comparative Example 1 even at a position 10 mm behind the upstream in the flow direction. It was confirmed.
Further, from the comparison of each example and each comparative example with respect to the above THC purification rate, the specific surface area of the oxide material coating layer is 9 m 2 / g or less and the coating amount is 10 g / L or more and 40 g / L or less. It was understood that it was necessary.

本発明の排ガス浄化用触媒によれば、リン成分を含む排ガスを放出する自動車などからの排ガスであってもリン被毒を抑制し、安定した排ガス浄化性能を達成することが可能である。   According to the exhaust gas purifying catalyst of the present invention, it is possible to suppress phosphorus poisoning and achieve stable exhaust gas purifying performance even for exhaust gas from an automobile or the like that releases exhaust gas containing a phosphorus component.

1 本発明の排ガス浄化用触媒
2 基材
3 三元触媒の触媒コート層
4 酸化物材料コート層
1 catalyst for purifying exhaust gas of the present invention 2 base material 3 catalyst coat layer of three-way catalyst 4 oxide material coat layer

Claims (3)

三元触媒の触媒コート層表面に酸化物材料をコートした排ガス浄化用触媒であって、前記酸化物材料の比表面積が9m/g以下で且つコート量が10g/L以上40g/L以下であることを特徴とする排ガス浄化用触媒。 A catalyst for exhaust gas purification in which the surface of a catalyst coat layer of a three-way catalyst is coated with an oxide material, wherein the oxide material has a specific surface area of 9 m 2 / g or less and a coating amount of 10 g / L or more and 40 g / L or less. An exhaust gas purifying catalyst characterized by being. 前記酸化物材料がさらに1種類以上の希土類元素を含む請求項1に記載の排ガス浄化用触媒。   The exhaust gas-purifying catalyst according to claim 1, wherein the oxide material further contains one or more rare earth elements. 前記酸化物材料が、セリア、ジルコニアおよびアルミナのうちの少なくとも1種類を含む請求項1又は2に記載の排ガス浄化用触媒。   The exhaust gas purifying catalyst according to claim 1 or 2, wherein the oxide material includes at least one of ceria, zirconia, and alumina.
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JP2013091585A (en) * 2011-10-26 2013-05-16 Tosoh Corp Zirconia powder, method for producing the same, and its application
EP2952251B1 (en) * 2013-01-31 2022-06-01 Umicore Shokubai Japan Co., Ltd. Exhaust-gas purification catalyst and its use
WO2015087873A1 (en) 2013-12-13 2015-06-18 株式会社キャタラー Exhaust purification catalyst
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