JP2002001119A - Method for manufacturing catalyst for purification of exhaust gas and catalyst for purification of exhaust gas manufactured by that method - Google Patents
Method for manufacturing catalyst for purification of exhaust gas and catalyst for purification of exhaust gas manufactured by that methodInfo
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- JP2002001119A JP2002001119A JP2000181129A JP2000181129A JP2002001119A JP 2002001119 A JP2002001119 A JP 2002001119A JP 2000181129 A JP2000181129 A JP 2000181129A JP 2000181129 A JP2000181129 A JP 2000181129A JP 2002001119 A JP2002001119 A JP 2002001119A
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- Prior art keywords
- exhaust gas
- carrier
- catalyst
- salt
- solution
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、排気ガスの浄化に
用いられる触媒、特に自動車の排気ガス浄化用触媒の製
造方法及びその製造方法により得られる触媒に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst used for purifying exhaust gas, and more particularly to a method for producing an exhaust gas purifying catalyst for an automobile and a catalyst obtained by the method.
【０００２】[0002]
【従来の技術】近年、リーンバーン自動車排ガスの浄化
用触媒として、ＮＯｘ吸蔵還元型触媒が広く使用されて
いる。このＮＯｘ吸蔵還元型触媒は白金、パラジウム等
の触媒活性を有する貴金属粒子と、主にバリウム等のア
ルカリ土類金属の炭酸塩を、アルミナ、ジルコニアのセ
ラミックのペレット状又はハニカム成形体若しくはセラ
ミックをコーティングした金属ハニカムといった多孔質
体である担体上に担持されたものである。このＮＯｘ吸
蔵還元型触媒において、貴金属粒子はＮＯｘの分解を促
進するための触媒成分として作用し、一方のアルカリ土
類金属はＮＯｘの吸蔵剤としての役割を有するものであ
り、ＮＯｘの分解が困難な酸化雰囲気においては硝酸塩
の形態でＮＯｘを吸蔵し、ＮＯｘの分解が容易となる還
元雰囲気に転じた際にこの吸蔵したＮＯｘを瞬時に分解
すべく開放するようになっている。2. Description of the Related Art In recent years, NOx storage reduction type catalysts have been widely used as catalysts for purifying lean burn automobile exhaust gas. This NOx storage reduction type catalyst is coated with noble metal particles having catalytic activity such as platinum and palladium, and carbonates of alkaline earth metals such as barium, and pellets of alumina or zirconia, or honeycomb molded bodies or ceramics. Supported on a carrier such as a metal honeycomb formed of a porous material. In this NOx storage reduction catalyst, the noble metal particles act as a catalyst component for accelerating the decomposition of NOx, while the alkaline earth metal has a role as a NOx storage agent, and it is difficult to decompose NOx. In an oxidizing atmosphere, NOx is stored in the form of nitrate, and when the atmosphere is changed to a reducing atmosphere in which NOx can be easily decomposed, the stored NOx is released so as to be immediately decomposed.
【０００３】かかるＮＯｘ吸蔵型触媒は、担体に貴金属
塩の水溶液（例えば、ジニトロジアンミン硝酸塩水溶
液）を担体に吸着させて水溶液中の分子状貴金属を担体
表面に吸着させることにより従来製造されている。ま
た、バリウムなどのアルカリ土類金属については、担体
に所定濃度の酢酸塩、炭酸塩バリウム等の水溶液を吸着
させて焼成し、その後に貴金属の担持をするようにして
いる。[0003] Such NOx storage catalysts are conventionally manufactured by adsorbing an aqueous solution of a noble metal salt (for example, an aqueous solution of dinitrodiammine nitrate) on a carrier and adsorbing the molecular noble metal in the aqueous solution on the surface of the carrier. For alkaline earth metals such as barium, a carrier is adsorbed with a predetermined concentration of an aqueous solution of acetate or barium carbonate or the like and calcined, and then the noble metal is loaded.
【０００４】ところで、従来のＮＯｘ吸蔵還元型触媒
は、耐熱性に乏しく連続運転により触媒活性、ＮＯｘ吸
蔵量が低下するという問題が生じていた。この触媒活性
及びＮＯｘ吸蔵量の経時的低下の要因の１つに熱劣化が
あり、排気温が高温となる運転により貴金属が酸化され
て触媒製造時の担持位置から離脱・拡散し易くなり、他
の貴金属粒子と結合し貴金属粒子の粒成長が生じるため
有効表面積が低下するところにあるものされている。そ
して、このような貴金属粒子の粒成長は、貴金属粒子の
粒径が小さければ小さいほど生じ易く、従来の原子状、
分子状貴金属を担持させた触媒には貴金属粒子径が小さ
いことから触媒活性の低下が生じるものと考えられてい
る。[0004] The conventional NOx storage-reduction type catalyst has a problem in that the catalyst activity and the NOx storage amount decrease due to poor heat resistance and continuous operation. Thermal degradation is one of the factors that cause the catalyst activity and NOx occlusion amount to decrease over time. Precious metals are oxidized by the operation in which the exhaust gas temperature rises, and are easily separated and diffused from the loading position during catalyst production. Noble metal particles are combined with the noble metal particles to cause grain growth, so that the effective surface area is reduced. Such noble metal particle growth is more likely to occur as the size of the noble metal particle is smaller.
It is considered that the catalyst loaded with the molecular noble metal has a small noble metal particle diameter, and thus causes a decrease in catalytic activity.
【０００５】そこで、本発明者らは、ＮＯｘ吸蔵還元型
触媒の製造工程に関し、分子状貴金属を含む水溶液に替
えて貴金属コロイド溶液を担体に吸着させる方法を提唱
している。ここで、コロイド溶液とは、多数の貴金属原
子が凝集してなる粒径１〜数十ｎｍの微小粒子（コロイ
ド粒子）が液体溶媒中に分散、懸濁したものをいう。コ
ロイド溶液を使用することにより原子状・分子状金属を
担持させる場合よりも大きな粒径の金属粒子を担持させ
ることができるため粒成長を抑制することができると共
に、粒子径を適当な範囲とすることで触媒活性を保持す
ることが可能となる。また、コロイド溶液を使用するメ
リットとしては、複数の貴金属の凝集するコロイド粒子
が懸濁するコロイド溶液を用いることで、容易に複数の
貴金属を複合的に担持させることができることが揚げら
れる。即ち、ロジウムのように担体であるアルミナと親
和力の大きい貴金属を白金と複合担持することで貴金属
粒子の離脱・拡散を抑制することができるのである。Therefore, the present inventors have proposed a method of adsorbing a noble metal colloid solution onto a carrier in place of an aqueous solution containing a molecular noble metal in the production process of a NOx storage reduction catalyst. Here, the colloid solution refers to a solution in which fine particles (colloid particles) having a particle diameter of 1 to several tens of nm formed by aggregating a large number of noble metal atoms are dispersed and suspended in a liquid solvent. By using a colloidal solution, it is possible to carry metal particles having a larger particle diameter than in the case of carrying atomic and molecular metals, so that grain growth can be suppressed and the particle diameter is set to an appropriate range. This makes it possible to maintain the catalytic activity. Another advantage of using a colloidal solution is that the use of a colloidal solution in which a plurality of noble metal agglomerated colloidal particles are suspended allows a plurality of noble metals to be easily supported in a complex manner. That is, detachment and diffusion of the noble metal particles can be suppressed by carrying a noble metal having a high affinity for alumina as a carrier, such as rhodium, in combination with platinum.
【０００６】そして、本発明者らはこのコロイド溶液を
用いたＮＯｘ吸蔵還元型触媒の製造において、ポリビニ
ルピロリドン（以下、ＰＶＰという。）を貴金属粒子の
保護剤としてコロイド溶液に添加してこのコロイド溶液
を担体に吸着する方法を提唱している。この保護剤と
は、コロイド溶液中でコロイド粒子の周辺に化学的又は
物理的に結合、吸着する化合物であって、コロイド粒子
同志の凝集を抑制し粒径分布を適性範囲に制御し安定化
させるものをいう。つまり、保護剤をコロイド溶液に添
加することでコロイド粒子の粒径を触媒に対して適当な
範囲（１〜５ｎｍ程度である）とし、安定した状態で担
体に吸着させることができる。In the production of a NOx storage-reduction type catalyst using this colloid solution, the present inventors added polyvinylpyrrolidone (hereinafter referred to as PVP) to the colloid solution as a protective agent for noble metal particles. A method for adsorbing carboxylic acid on a carrier has been proposed. This protective agent is a compound that chemically or physically binds and adsorbs to the periphery of colloid particles in a colloid solution, suppresses aggregation of the colloid particles and controls and stabilizes the particle size distribution within an appropriate range. A thing. That is, by adding the protective agent to the colloid solution, the particle size of the colloid particles can be adjusted to an appropriate range (about 1 to 5 nm) for the catalyst, and the colloid particles can be stably adsorbed on the carrier.
【０００７】しかしながら、本発明者らの検討の結果、
ＰＶＰ混合コロイド溶液を用いて触媒を製造した場合、
特に、ペレット状担体やセラミックコーティングしたハ
ニカム担体に対する吸着速度が著しく低いことが明らか
となっている。このようにコロイド溶液の担体に対する
吸着速度が低い場合、触媒の生産性を著しく低下させる
こととなる。また、コロイド溶液の吸着速度が低い場
合、十分な時間をかけなければ所要量の貴金属を担体に
吸着させることができない。ここで貴金属の担持分布は
空間速度の高い自動車排ガス触媒にあっては、触媒自体
の活性に影響を与えるものである。However, as a result of the study by the present inventors,
When a catalyst is produced using a PVP mixed colloid solution,
In particular, it has been clarified that the adsorption speed for pellet-shaped carriers and ceramic-coated honeycomb carriers is extremely low. When the rate of adsorption of the colloidal solution to the carrier is low, the productivity of the catalyst is significantly reduced. In addition, when the adsorption speed of the colloid solution is low, a sufficient amount of noble metal cannot be adsorbed on the carrier unless sufficient time is taken. Here, the distribution of noble metal loading affects the activity of the catalyst itself in the case of an automobile exhaust gas catalyst having a high space velocity.
【０００８】[0008]
【発明が解決しようとする課題】本発明は以上のような
背景の下なされたものであり、貴金属コロイド溶液に保
護剤を添加しこれを担体に吸着させてなる排気ガス浄化
用触媒の製造方法に関して、ペレット状担体やセラミッ
クコーティングしたハニカム担体を用いた場合において
も速やかに貴金属を吸着・担持させることができる排気
ガス浄化用触媒の製造方法を提供することを目的とす
る。SUMMARY OF THE INVENTION The present invention has been made under the above-mentioned background, and a method for producing a catalyst for purifying exhaust gas, comprising adding a protective agent to a noble metal colloid solution and adsorbing the same on a carrier. Accordingly, an object of the present invention is to provide a method for producing an exhaust gas purifying catalyst capable of rapidly adsorbing and supporting a noble metal even when a pellet-shaped carrier or a ceramic carrier coated with a honeycomb carrier is used.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、ＰＶＰを
保護剤としたコロイド溶液の担体に関する吸着速度の問
題点について検討したところ、その原因が保護剤を含め
た貴金属粒子の粒子径が過大である点にあるとの考察に
至った。そして、貴金属粒子径が小さくなるような保護
剤を用いた触媒の製造法について鋭意研究を行った結
果、本発明を想到するに至った。Means for Solving the Problems The present inventors have examined the problem of the adsorption rate of a colloid solution using PVP as a protective agent on a carrier, and found that the cause was that the particle size of the noble metal particles including the protective agent was reduced. It was concluded that the point was too large. Then, as a result of diligent research on a method for producing a catalyst using a protective agent that reduces the noble metal particle diameter, the present invention has been reached.
【００１０】即ち、本願請求項１記載の発明は、１種又
は２種以上の貴金属塩と水又は水と有機溶媒との混合溶
媒若しくは有機溶媒とからなる溶媒と保護剤と混合し、
この混合溶液を還流することにより溶液中の貴金属イオ
ンを還元して貴金属粒子が懸濁するコロイド溶液を製造
し、コロイド溶液を多孔質体である担体に吸着させる排
ガス浄化触媒の製造方法において、保護剤として４級ア
ンモニウム塩を混合したコロイド溶液を吸着させる排ガ
ス浄化触媒の製造方法である。That is, the invention according to claim 1 of the present application comprises mixing one or more kinds of noble metal salts with water or a mixed solvent of water and an organic solvent or an organic solvent with a protective agent,
By refluxing the mixed solution, a noble metal ion in the solution is reduced to produce a colloidal solution in which the noble metal particles are suspended, and the colloidal solution is adsorbed on a porous carrier. This is a method for producing an exhaust gas purifying catalyst that adsorbs a colloid solution mixed with a quaternary ammonium salt as an agent.
【００１１】４級アンモニウム塩はＰＶＰに比して著し
く分子量が小さいことから、コロイド溶液中でコロイド
粒子上に配位したときの全体の粒子径はＰＶＰを添加し
た場合よりも小さくなるものと考えられる。従って、本
願請求項１記載の発明によれば、担体の種類を問わず速
やかにコロイド溶液を担体に吸着することができ、触媒
の生産性を向上させることができる。Since the quaternary ammonium salt has a significantly smaller molecular weight than PVP, it is considered that the overall particle size when coordinated on the colloid particles in the colloid solution is smaller than that when PVP is added. Can be Therefore, according to the first aspect of the present invention, the colloid solution can be quickly adsorbed to the carrier regardless of the type of the carrier, and the productivity of the catalyst can be improved.
【００１２】また、４級アンモニウム塩はＰＶＰと同
様、貴金属粒子に対する親和性が良好で、コロイド溶液
中で貴金属粒子表面に容易に配位することから保護剤と
しても十分な効果を有し、コロイド粒子の粗大化を抑制
すると共にコロイド粒子を均一に分散させることができ
る。従って、請求項１記載のコロイド溶液により触媒を
製造する場合、その触媒の活性を十分なものとすること
ができる。Quaternary ammonium salts, like PVP, have good affinity for noble metal particles and easily coordinate with the surface of noble metal particles in a colloid solution, so that they have a sufficient effect as a protective agent. It is possible to suppress coarsening of the particles and to uniformly disperse the colloid particles. Therefore, when a catalyst is produced from the colloid solution according to claim 1, the activity of the catalyst can be made sufficient.
【００１３】そして、コロイド溶液に添加する４級アン
モニウム塩としては、請求項２記載のように、炭素数１
〜４のアルキル基を少なくとも１つ有する４級アンモニ
ウムを添加するのが好ましい。つまり、保護剤である４
級アンモニウム塩が有する置換基の少なくとも一つを短
鎖のアルキル基とするものである。これは、保護剤を添
加した状態のコロイド溶液を親水性とするためである。
特に、自動車排ガス触媒の製造においては、従来技術に
あるように水溶性貴金属化合物を水に溶解させて製造す
るのが一般的となっていることから、本発明で新たに有
機溶媒を使用するとなれば、その引火性や作業環境を新
たに考慮する必要があり工業的に困難となるからであ
る。[0013] The quaternary ammonium salt to be added to the colloid solution is preferably a compound having 1 carbon atom.
It is preferable to add a quaternary ammonium having at least one alkyl group. That is, the protective agent 4
At least one of the substituents of the quaternary ammonium salt is a short-chain alkyl group. This is to make the colloid solution with the protective agent added hydrophilic.
In particular, in the production of automobile exhaust gas catalysts, since it is common to dissolve a water-soluble noble metal compound in water as in the prior art, an organic solvent can be newly used in the present invention. If, for example, its flammability and work environment need to be newly considered, it becomes industrially difficult.
【００１４】また、本発明で添加する４級アンモニウム
塩として更に望ましいものとしては、請求項４記載のよ
うに、硫黄及び塩素を含有しない４級アンモニウム塩と
するのが好ましい。硫黄が含有されている触媒コロイド
溶液により触媒を製造した場合、その硫黄は担体上の触
媒層内に残留することとなり触媒被毒の要因となるから
である。また、塩素の場合についても塩素が触媒層に残
留した場合、この塩素に起因して触媒反応ガス中に塩化
水素ガスが混入し触媒を搭載する装置に腐食の問題が生
じるからである。Further, as a quaternary ammonium salt to be added in the present invention, a quaternary ammonium salt containing no sulfur and chlorine is preferable. This is because, when a catalyst is produced using a catalyst colloid solution containing sulfur, the sulfur remains in the catalyst layer on the carrier and becomes a factor of catalyst poisoning. Also, in the case of chlorine, when chlorine remains in the catalyst layer, hydrogen chloride gas is mixed into the catalytic reaction gas due to the chlorine, causing a problem of corrosion in a device on which the catalyst is mounted.
【００１５】このような塩素及び硫黄を含有しないとい
う条件を具備する４級アンモニウム塩としては、短鎖で
塩素及び硫黄を含有しないアルキル基を有する４級アン
モニウム塩として、テトラメチルアンモニウム塩、テト
ラエチルアンモニウム塩、テトラ−ｎ−プロピルアンモ
ニウム塩、テトライソプロピルアンモニウム塩、テトラ
ブチルアンモニウム塩、ベンジルトリメチルアンモニウ
ム塩が揚げられる。The quaternary ammonium salts satisfying the condition that they do not contain chlorine and sulfur include tetramethylammonium salts and tetraethylammonium salts as quaternary ammonium salts having a short-chain alkyl group containing no chlorine and sulfur. Salts, tetra-n-propylammonium salts, tetraisopropylammonium salts, tetrabutylammonium salts, benzyltrimethylammonium salts are fried.
【００１６】また、塩素及び硫黄を含有しない方が好ま
しいのは４級アンモニウム塩の陰イオン成分についても
同様である。従って、本発明で使用される４級アンモニ
ウム塩としては、陰イオン成分が硫酸イオン、塩素イオ
ンである硫酸塩、塩化物では適当ではなく、請求項５記
載のように、陰イオン成分が水酸化物イオン、酢酸イオ
ン、炭酸イオン、硝酸イオン、亜硝酸イオンである酸化
物、酢酸塩、炭酸塩、硝酸塩、亜硝酸塩の少なくとも１
種を添加するのが好ましい。、It is preferable that chlorine and sulfur are not contained in the quaternary ammonium salt as well. Therefore, as the quaternary ammonium salt used in the present invention, sulfates and chlorides whose anion component is a sulfate ion or a chloride ion are not suitable. At least one of oxides, acetates, carbonates, nitrates, and nitrites, which are compound ions, acetate ions, carbonate ions, nitrate ions, and nitrite ions.
Preferably, a seed is added. ,
【００１７】ところで、既に述べたように、本発明の対
象である排ガス浄化触媒触媒としては、貴金属粒子に加
えて、ＮＯｘ分解促進の目的でバリウム等のアルカリ土
類金属が担持されたものが一般に用いられている。この
ような排ガス浄化触媒触媒を製造するために、通常、貴
金属の担持に先立ってバリウム等が担持された担体を使
用するが、このような担体に対して本発明の４級アンモ
ニウム塩を保護剤としたコロイドを吸着させる場合は、
請求項６記載のように、コロイド溶液にキレート剤を添
加し、コロイド溶液を担体に吸着させるのが好ましい。As described above, the catalyst for purifying exhaust gas, which is the object of the present invention, is generally a catalyst carrying an alkaline earth metal such as barium in order to promote the decomposition of NOx in addition to the noble metal particles. Used. In order to manufacture such an exhaust gas purifying catalyst, a carrier on which barium or the like is supported is usually used prior to supporting the noble metal, and the quaternary ammonium salt of the present invention is used as a protective agent for such a carrier. When adsorbing colloids
As described in claim 6, it is preferable that a chelating agent is added to the colloid solution so that the colloid solution is adsorbed on the carrier.
【００１８】このようにすることの理由としては、本発
明者らの本願発明に関する更なる検討の結果、アルカリ
土類金属が予め担持された担体に、本発明の触媒コロイ
ドを吸着させようとした場合、貴金属粒子の吸着速度が
通常の担体（アルカリ土類金属担持なしの担体）を用い
た場合よりも低くなるという知見によるものである。そ
して、本発明者らによれば、このような吸着速度の低下
は、４級アンモニウム塩が配位した貴金属コロイド粒子
は、コロイド中にアルカリ土類金属（イオン）が共存す
る場合、アルカリ土類金属イオンと塩析反応を生じ凝集
するために生じるものであると考えられる。The reason for this is that as a result of further studies on the present invention by the present inventors, an attempt was made to adsorb the catalyst colloid of the present invention on a carrier on which an alkaline earth metal was previously supported. In this case, it is based on the finding that the adsorption speed of the noble metal particles is lower than that in the case of using a normal carrier (a carrier without supporting an alkaline earth metal). According to the present inventors, such a decrease in the adsorption rate is caused by the fact that the noble metal colloid particles to which the quaternary ammonium salt is coordinated, when an alkaline earth metal (ion) coexists in the colloid, It is considered that the salting out reaction occurs with the metal ions to cause aggregation.
【００１９】請求項６記載の発明は、この貴金属コロイ
ド粒子とアルカリ土類金属イオンとの塩析を解決すべく
なされたものである。この請求項６記載の発明によれ
ば、キレート剤が担体から溶出するアルカリ土類金属イ
オンを捕捉することとなるため、コロイド中の貴金属粒
子はアルカリ土類金属イオンの影響を受けることなく速
やかに担体に吸着するのである。The invention described in claim 6 has been made to solve the salting out of the noble metal colloid particles and the alkaline earth metal ions. According to the invention of claim 6, since the chelating agent captures the alkaline earth metal ion eluted from the carrier, the noble metal particles in the colloid are promptly affected by the alkaline earth metal ion. It adsorbs on the carrier.
【００２０】ここでのキレート剤とは、バリウム等のア
ルカリ土類金属イオンと容易に反応してキレート化合物
を形成することができる多座配位子を有する化合物をい
う。このキレート剤としては、請求項７のように、配位
子としてカルボキシル基を２以上有する化合物が好まし
く、特に請求項８記載のエチレンジアンミン四酢酸（Ｅ
ＤＴＡ）が好ましい。The chelating agent herein means a compound having a polydentate ligand which can easily react with an alkaline earth metal ion such as barium to form a chelate compound. As the chelating agent, a compound having two or more carboxyl groups as ligands is preferable as described in claim 7, and particularly, ethylenediamminetetraacetic acid (E) described in claim 8 is preferable.
DTA) is preferred.
【００２１】尚、このキレート剤の添加量については、
コロイド溶液の容積、担体に担持されているアルカリ土
類金属の量により異なるが、コロイド溶液に対して０．
０１〜１．０ｗｔ％程度添加するのが好ましい。０．０
１ｗｔ％以下の添加量では溶出バリウムイオンの捕捉効
果がみられず、１．０ｗｔ％以上添加しても効果に変化
が見られず、吸着特性に変化はないからである。The amount of the chelating agent added is as follows:
It depends on the volume of the colloidal solution and the amount of the alkaline earth metal supported on the carrier.
It is preferable to add about 01 to 1.0 wt%. 0.0
This is because the addition of 1 wt% or less has no effect of capturing the eluted barium ions, and the addition of 1.0 wt% or more shows no change in the effect and no change in the adsorption characteristics.
【００２２】一方、請求項６の発明によれば、貴金属粒
子の吸着速度は問題ないいものの、折角担持したアルカ
リ土類金属が担体から溶出していることに変わりはな
い。従って、このアルカリ土類金属の溶出により触媒と
したときのアルカリ土類金属の効果が減少するものと考
えられる。そこで、本発明者らは、貴金属粒子の吸着速
度を維持しつつ、担体に担持されているアルカリ土類金
属の溶出を防止する方法として、請求項９記載の発明の
ように、コロイド溶液に更にアルカリ土類金属の塩を添
加してコロイド溶液を担体に吸着させるものとした。On the other hand, according to the invention of claim 6, although there is no problem in the adsorption speed of the noble metal particles, the alkali earth metal carried on the carrier is still eluted from the carrier. Therefore, it is considered that the effect of the alkaline earth metal when used as a catalyst is reduced by the elution of the alkaline earth metal. Therefore, the present inventors have proposed a method for preventing the elution of alkaline earth metal supported on a carrier while maintaining the adsorption rate of noble metal particles, as in the invention according to claim 9, wherein the colloidal solution is further added to the colloidal solution. An alkaline earth metal salt was added to adsorb the colloid solution to the carrier.
【００２３】請求項９記載の発明は、担体上のアルカリ
土類金属は、コロイド溶液中のアルカリ土類金属（イオ
ン）とのバランスにより溶出するとの考察に基づきなさ
れたものである。この請求項９記載の方法によれば、予
めコロイド溶液中にアルカリ土類金属塩を混合すること
で、コロイド溶液中のアルカリ土類金属イオン濃度が上
昇するので、担体からのアルカリ土類金属の溶出を抑制
することができる。The ninth aspect of the present invention is based on the consideration that the alkaline earth metal on the carrier is eluted in balance with the alkaline earth metal (ion) in the colloid solution. According to the method of claim 9, the alkaline earth metal ion concentration in the colloid solution is increased by previously mixing the alkaline earth metal salt in the colloid solution. Elution can be suppressed.
【００２４】このアルカリ土類金属塩の添加量は、担体
に予め担持されているアルカリ土類金属の量によるが、
コロイド溶液に対して５０〜５０００ｐｐｍ程度添加す
るのが好ましい。また、コロイド溶液に添加するアルカ
リ土類金属塩としては、例えば、硝酸塩の形態で添加す
るのが好ましい。The amount of the alkaline earth metal salt to be added depends on the amount of the alkaline earth metal previously supported on the carrier.
It is preferable to add about 50 to 5000 ppm to the colloid solution. As the alkaline earth metal salt to be added to the colloid solution, for example, it is preferable to add in the form of nitrate.
【００２５】尚、以上説明した排ガス浄化触媒触媒の製
造方法においては、コロイド溶液を担体に吸着させる方
法を特に限定するものではない。従って、コロイド溶液
（場合によってはキレート剤、アルカリ土類金属塩を添
加たコロイド溶液）をスプレーにて担体に吹き付けるこ
とによっても可能であるが、コロイド溶液を収容する槽
に担体を浸漬し、コロイド溶液を担体に吸着させる方が
好ましい。浸漬法によるほうが簡易にコロイド溶液を担
体に浸透させることができ、かつ、貴金属粒子を偏差な
く吸着させることができるからである。In the method for producing an exhaust gas purifying catalyst described above, the method for adsorbing the colloid solution on the carrier is not particularly limited. Therefore, it is also possible to spray a colloid solution (in some cases, a colloid solution containing a chelating agent or an alkaline earth metal salt) onto the carrier by spraying. It is preferred that the solution be adsorbed on the carrier. This is because the immersion method allows the colloid solution to easily penetrate the carrier and allows the noble metal particles to be adsorbed without deviation.
【００２６】また、本発明で使用するコロイド溶液とし
ては、貴金属粒子として白金、金、銀、パラジウム、ル
テニウム、ロジウム、イリジウム、オスミウムが懸濁し
たものであるが、このコロイド溶液を製造するためには
ジニトロジアンミン硝酸塩等の塩を溶媒に溶解させて製
造する。The colloid solution used in the present invention is a suspension of platinum, gold, silver, palladium, ruthenium, rhodium, iridium and osmium as noble metal particles. Is prepared by dissolving a salt such as dinitrodiammine nitrate in a solvent.
【００２７】[0027]
【発明の実施の形態】以下、本発明の好適と思われる実
施の形態について説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below.
【００２８】第１実施形態：２Ｌの水にジニトロジアン
ミン白金３．１２ｇ及び硝酸ロジウム０．２５ｇを溶解
させ、これにテトラヒドロフラン６００ｍＬとエタノー
ル８００ｍＬとを加え、更に保護剤として１５ｗｔ％の
水酸化テトラメチルアンモニウム水溶液８８．３６ｇを
添加し、これを１０時間加熱還流した。 First Embodiment : 3.12 g of dinitrodiammineplatinum and 0.25 g of rhodium nitrate are dissolved in 2 L of water, 600 mL of tetrahydrofuran and 800 mL of ethanol are added thereto, and 15 wt% of tetramethyl hydroxide as a protective agent is further added. An aqueous ammonium solution (88.36 g) was added, and the mixture was heated under reflux for 10 hours.
【００２９】この溶液を蒸発乾固した後、アセトン２５
００ｍＬ／水５００ｍＬの混合溶媒に再溶解させ、溶液
を蒸留してアセトンを除去し、さらに白金濃度が１ｗｔ
％となるまで濃縮し、テトラメチルアンモニウム−白金
／ロジウムバイメタリックコロイドを得た。After evaporating the solution to dryness, acetone 25
The solution was redissolved in a mixed solvent of 00 mL / 500 mL of water, and the solution was distilled to remove acetone.
% To obtain a tetramethylammonium-platinum / rhodium bimetallic colloid.
【００３０】そして、５０ｍＬの水にγ−アルミナ粉末
６．００ｇを分散させ、上記、白金／ロジウムコロイド
１０gを滴下した、３０分間室温にて攪拌して白金／ロ
ジウムコロイドをγ−アルミナ上に吸着担持させた。Then, 6.00 g of γ-alumina powder was dispersed in 50 mL of water, and 10 g of the above-mentioned platinum / rhodium colloid was added dropwise. The mixture was stirred at room temperature for 30 minutes to adsorb the platinum / rhodium colloid on γ-alumina. Supported.
【００３１】その後これを濾過し、１１０℃で２時間乾
燥後、４５０℃で２時間焼成して、白金／ロジウム担持
触媒を得た。尚、この触媒のアルミナ粉末１ｇ当たりの
白金担持量は０．０１６６ｇ、ロジウム担持量は９．６
６×１０−４ｇである。Thereafter, this was filtered, dried at 110 ° C. for 2 hours, and calcined at 450 ° C. for 2 hours to obtain a platinum / rhodium supported catalyst. The amount of supported platinum per gram of alumina powder of this catalyst was 0.0166 g, and the amount of supported rhodium was 9.6.
6 × 10 −4 g.
【００３２】比較例１：２Ｌの水にジニトロジアンミン
白金３．１２ｇ及び硝酸ロジウム０．２５ｇを溶解さ
せ、これにエタノール５００ｍＬを加え、更に保護剤と
してＰＶＰを添加し、これを８時間加熱還流した。 Comparative Example 1 : 3.12 g of dinitrodiammineplatinum and 0.25 g of rhodium nitrate were dissolved in 2 L of water, 500 mL of ethanol was added thereto, PVP was further added as a protective agent, and the mixture was heated and refluxed for 8 hours. .
【００３３】この溶液を蒸留して白金濃度が４ｗｔ％と
なるまで濃縮し、ＰＶＰ保護白金／ロジウムバイメタリ
ックコロイドを得た。This solution was distilled and concentrated until the platinum concentration became 4 wt% to obtain a PVP-protected platinum / rhodium bimetallic colloid.
【００３４】そして、５０ｍＬの水にγ−アルミナ粉末
６．００ｇを分散させ、上記、白金／ロジウムコロイド
２．５ｇを滴下した、３０分間室温にて攪拌して白金／
ロジウムコロイドをγ−アルミナ上に吸着担持させた。Then, 6.00 g of γ-alumina powder was dispersed in 50 mL of water, and 2.5 g of the above-mentioned platinum / rhodium colloid was added dropwise.
Rhodium colloid was adsorbed and supported on γ-alumina.
【００３５】その後、第１実施形態と同様の操作を行
い、白金／ロジウム担持触媒を得た。尚、この触媒のア
ルミナ粉末１ｇ当たりの白金担持量は０．０１６６ｇ、
ロジウム担持量は９．６６×１０−４ｇである。Thereafter, the same operation as in the first embodiment was performed to obtain a platinum / rhodium supported catalyst. The amount of platinum carried per gram of alumina powder of this catalyst was 0.0166 g,
The amount of rhodium supported is 9.66 × 10 −4 g.
【００３６】比較例２：５０ｍＬの水にγ−アルミナ粉
末６．００ｇを分散させ、これにジニトロジアンミン白
金錯体を含む硝酸水溶液（含有白金量：０．１ｇ）を滴
下した、３０分間室温にて攪拌してジニトロジアンミン
白金をγ−アルミナ上に吸着担持させた。 Comparative Example 2 : 6.00 g of γ-alumina powder was dispersed in 50 mL of water, and an aqueous nitric acid solution (containing platinum: 0.1 g) containing a dinitrodiammine platinum complex was added dropwise thereto. With stirring, dinitrodiammine platinum was adsorbed and supported on γ-alumina.
【００３７】そして、第１実施形態と同様の操作により
担持触媒を得た。尚、この触媒のアルミナ粉末１ｇ当た
りの白金担持量は０．０１６６ｇである。Then, a supported catalyst was obtained by the same operation as in the first embodiment. The amount of platinum carried per gram of alumina powder of this catalyst was 0.0166 g.
【００３８】実験例１（耐熱試験）：第１実施形態及び
比較例１、２において製造した触媒について、空気中で
８００℃にて５時間加熱し、触媒上の貴金属粒子の粒径
を測定し、各触媒の貴金属粒子の粗大化の状況を検討し
た。貴金属粒子径の測定はＸＲＤ（Ｘ線回折）により得
られた回折像をデバイ−シェラー法にて求めている。こ
のようにして測定された加熱前後の触媒の貴金属粒子の
粒径の値を表１に示す。 Experimental Example 1 (Heat Resistance Test) : The catalysts produced in the first embodiment and Comparative Examples 1 and 2 were heated in air at 800 ° C. for 5 hours, and the particle size of the noble metal particles on the catalyst was measured. Then, the situation of coarsening of the noble metal particles of each catalyst was examined. In the measurement of the noble metal particle diameter, a diffraction image obtained by XRD (X-ray diffraction) is obtained by the Debye-Scherrer method. Table 1 shows the values of the particle diameters of the noble metal particles of the catalyst measured before and after heating as described above.
【００３９】[0039]
【表１】 [Table 1]
【００４０】表１より、第１実施形態において製造され
た触媒においては、加熱後の貴金属粒子の粒子径が、比
較例２のＰＶＰを保護剤としたコロイド溶液から製造し
た触媒のものとほぼ同じであった。そして、これらの値
は、粒成長が生じていると推察される分子状貴金属塩溶
液（ジニトロジアンミン白金錯体溶液）を吸収させて製
造した触媒の値と比して小さい。従って、本発明に係る
４級アンモニウム塩を用いた触媒は、ＰＶＰと同様の貴
金属粒子の粒成長の抑制効果を有することが確認され
た。According to Table 1, in the catalyst manufactured in the first embodiment, the particle size of the noble metal particles after heating was almost the same as that of the catalyst manufactured from the colloidal solution using PVP as a protective agent in Comparative Example 2. Met. These values are smaller than those of the catalyst produced by absorbing a molecular noble metal salt solution (a dinitrodiammine platinum complex solution) which is presumed to have caused grain growth. Therefore, it was confirmed that the catalyst using the quaternary ammonium salt according to the present invention has the same effect of suppressing the growth of noble metal particles as PVP.
【００４１】実験例２（触媒性能の検討）：実験例１に
より高温耐久性試験を行った後の第１実施形態、比較例
１及び２の各触媒について、その触媒性能を検討した。
実験は、各触媒と下記組成からなる反応ガスとを接触さ
せて、飽和するまでガス吸蔵を行わせ、ＮＯｘ吸蔵量を
ＴＧ−ＤＴＡ（熱質量−示差熱分析）にて測定した。表
２はその結果を示す。 Experimental Example 2 (Study on Catalyst Performance) : The catalyst performance of each catalyst of the first embodiment and Comparative Examples 1 and 2 after the high-temperature durability test was conducted in Experimental Example 1 was examined.
In the experiment, each catalyst was brought into contact with a reaction gas having the following composition to perform gas occlusion until saturation, and the NOx occlusion amount was measured by TG-DTA (thermal mass-differential thermal analysis). Table 2 shows the results.
【００４２】 [0042]
【００４３】[0043]
【表２】 [Table 2]
【００４４】表２より、第１実施形態の触媒は、８００
℃で１０時間加熱した後であっても、ＮＯｘ吸蔵触媒と
しての活性を有し、そのＮＯｘ吸蔵量も１８．６ｍｇ／
ｇとＰＶＰを使用した比較例１とほぼ同じである。一
方、比較例２においては、ＮＯｘ吸蔵量が１１．３ｍｇ
／ｇと低く、これは加熱により活性が低下したものとい
える。この活性の低下は、加熱により貴金属粒子が粒成
長したのが原因と考えられる。この結果からも、本発明
のコロイド溶液によれば、粒成長することない触媒を製
造することができることが確認された。As shown in Table 2, the catalyst of the first embodiment is 800
Even after heating at 10 ° C. for 10 hours, it has activity as a NOx storage catalyst, and its NOx storage amount is 18.6 mg /
This is almost the same as Comparative Example 1 using g and PVP. On the other hand, in Comparative Example 2, the NOx storage amount was 11.3 mg.
/ G, which means that the activity was reduced by heating. This decrease in activity is considered to be caused by the growth of the noble metal particles by heating. From these results, it was confirmed that the colloid solution of the present invention can produce a catalyst without causing grain growth.
【００４５】第３実施形態：本実施形態では、第１実施
形態で使用したテトラメチルアンモニウム−白金／ロジ
ウムコロイド溶液をセラミックコートしたハニカム担体
に吸着させて触媒を製造した。 Third Embodiment In this embodiment, a catalyst was produced by adsorbing the tetramethylammonium-platinum / rhodium colloid solution used in the first embodiment on a ceramic-coated honeycomb carrier.
【００４６】第１実施形態で製造したコロイドを白金濃
度が２００ｐｐｍになるまで水で希釈し、１５０ｍＬ採
り、これにアルミナをコートしたハニカム担体（アルミ
ナ量：２．８５ｇ）を浸漬した。The colloid produced in the first embodiment was diluted with water until the platinum concentration became 200 ppm, and 150 mL of the colloid was diluted with an alumina-coated honeycomb carrier (alumina amount: 2.85 g).
【００４７】そして、担体を溶液中から取り出し、１１
０℃で２時間乾燥後、４５０℃で２時間焼成して、白金
／ロジウム担持触媒を得た。Then, the carrier is taken out of the solution, and 11
After drying at 0 ° C. for 2 hours, it was calcined at 450 ° C. for 2 hours to obtain a platinum / rhodium supported catalyst.
【００４８】比較例３：ここでは、比較例１で使用した
ＰＶＰ−白金／ロジウムコロイド溶液を第３実施形態と
同様にセラミックコートしたハニカム担体に吸着させて
触媒を製造した。 Comparative Example 3 Here, the catalyst was produced by adsorbing the PVP-platinum / rhodium colloid solution used in Comparative Example 1 on a ceramic-coated honeycomb carrier as in the third embodiment.
【００４９】比較例１で製造したコロイドを白金濃度が
２００ｐｐｍになるまで水で希釈し、１５０ｍＬ採り、
これにアルミナをコートしたハニカム担体（アルミナ
量：２．８５ｇ）を浸漬した。The colloid produced in Comparative Example 1 was diluted with water until the platinum concentration reached 200 ppm, and 150 mL was taken.
A honeycomb carrier coated with alumina (alumina amount: 2.85 g) was immersed in this.
【００５０】そして、担体を溶液中から取り出し、１１
０℃で２時間乾燥後、４５０℃で２時間焼成して、白金
／ロジウム担持触媒を得た。Then, the carrier is taken out of the solution and
After drying at 0 ° C. for 2 hours, it was calcined at 450 ° C. for 2 hours to obtain a platinum / rhodium supported catalyst.
【００５１】実験例３：上記第３実施形態及び比較例３
の触媒の製造過程において、コロイド溶液の吸着速度を
比較した。実験は、溶液を攪拌しつつ、一定時間毎に溶
液をサンプリングして白金濃度をＩＣＰ（誘導結合プラ
ズマ発光分光分析）にて測定した。尚、比較のためジニ
トロジアンミン白金錯体を含む硝酸水溶液の担体に対す
る吸着速度も測定した。 Experimental Example 3 : The third embodiment and comparative example 3
In the production process of the catalyst of No. 1, the adsorption speed of the colloid solution was compared. In the experiment, the solution was sampled at regular intervals while stirring the solution, and the platinum concentration was measured by ICP (inductively coupled plasma emission spectroscopy). For comparison, the adsorption rate of a nitric acid aqueous solution containing a dinitrodiammine platinum complex on a carrier was also measured.
【００５２】図１は、担体を浸漬したときの各溶液の白
金濃度の変化を示す。この図から、第３実施形態（保護
剤：水酸化テトラメチルアンモニウム）を吸着させたと
きの白金濃度の減少速度（即ち、白金吸着速度）は比較
例３（保護剤：ＰＶＰ）のそれより著しく低くなってお
り、約４時間程度で吸着が完了した。また、この吸着速
度は、ジニトロジアンミン白金錯体水溶液のものとほぼ
同等であった。従って、本発明のコロイド溶液は担体が
ハニカム上のセラミックコーティング層であっても十分
速やかに吸着させることができることが確認された。FIG. 1 shows the change in the platinum concentration of each solution when the carrier was immersed. From this figure, it can be seen that the rate of decrease of the platinum concentration when the third embodiment (protective agent: tetramethylammonium hydroxide) is adsorbed (that is, the platinum adsorption rate) is significantly higher than that of Comparative Example 3 (protective agent: PVP). The adsorption was completed in about 4 hours. The adsorption rate was almost the same as that of the dinitrodiammine platinum complex aqueous solution. Therefore, it was confirmed that the colloid solution of the present invention can be sufficiently quickly adsorbed even if the carrier is a ceramic coating layer on a honeycomb.
【００５３】第４実施形態：本実施形態では、担体にバ
リウムが予め担持されたハニカム担体を用い、コロイド
溶液中にキレート剤としてエチレンジアンミン四酢酸を
添加して、第３実施形態と同様の方法にて触媒を製造し
た。 Fourth Embodiment : In this embodiment, a honeycomb carrier having barium previously supported on a carrier is used, and ethylenediamminetetraacetic acid is added as a chelating agent to a colloidal solution. Produced a catalyst.
【００５４】第３実施形態と同じコロイド溶液（白金濃
度：２００ｐｐｍ）１５０ｍＬにキレート剤としてエチ
レンジアンミン四酢酸０．５ｇ（０．３３ｗｔ％）を添
加し、溶解した後、これにアルミナをコートしたハニカ
ム担体（アルミナ量：２．８５ｇ）を浸漬した。To 150 mL of the same colloidal solution (platinum concentration: 200 ppm) as in the third embodiment, 0.5 g (0.33 wt%) of ethylene diamminetetraacetic acid was added as a chelating agent, dissolved, and then dissolved in a honeycomb coated with alumina. A carrier (alumina amount: 2.85 g) was immersed.
【００５５】担体へコロイド溶液を吸着させた後は、第
３実施形態と同様の処理により白金／ロジウム担持触媒
を製造した。After the colloid solution was adsorbed on the carrier, a platinum / rhodium supported catalyst was produced by the same treatment as in the third embodiment.
【００５６】実験例４：この触媒製造工程において、実
験例３と同様、一定時間毎に溶液をサンプリングして白
金濃度を測定し吸着速度を検討した。 Experimental Example 4 In this catalyst production process, as in Experimental Example 3, the solution was sampled at regular intervals, the platinum concentration was measured, and the adsorption rate was examined.
【００５７】図２は、担体を浸漬した状態の各溶液の白
金濃度の変化を示す。本実験例においても、ジニトロジ
アンミン白金錯体を含む硝酸水溶液の吸着速度を測定し
比較している。この図から、本実施形態のように予めバ
リウムを担持した担体についても、コロイド溶液中にキ
レート剤を添加することで、ジニトロジアンミン白金錯
体を含む硝酸水溶液のと同等の吸着速度で貴金属粒子が
吸着することが確認された。FIG. 2 shows the change in the platinum concentration of each solution with the carrier immersed. Also in this experimental example, the adsorption speed of the nitric acid aqueous solution containing the dinitrodiammine platinum complex was measured and compared. From this figure, it can be seen that the carrier preloaded with barium as in the present embodiment also shows that the addition of the chelating agent to the colloid solution allows the noble metal particles to be adsorbed at the same adsorption rate as the nitric acid aqueous solution containing the dinitrodiammine platinum complex. It was confirmed that.
【００５８】第５実施形態：本実施形態では、第４実施
形態と同じバリウム担持担体を用い、コロイド溶液中に
キレート剤とバリウム塩を添加して、第４実施形態と同
様の方法にて触媒を製造した。 Fifth Embodiment : In this embodiment, the same barium carrier as in the fourth embodiment is used, and a chelating agent and a barium salt are added to a colloid solution, and the catalyst is produced in the same manner as in the fourth embodiment. Was manufactured.
【００５９】コロイド溶液（白金濃度：２００ｐｐｍ）
１５０ｍＬにキレート剤としてエチレンジアンミン四酢
酸０．５ｇ（０．３３ｗｔ％）を添加し、更に、バリウ
ム塩として硝酸バリウムを添加した後、これにアルミナ
をコートしたハニカム担体（アルミナ量：２．８５ｇ）
を浸漬した。この際のコロイド溶液としては、５００ｐ
ｐｍ、１０００ｐｐｍと硝酸バリウムの添加量を変化さ
せて２種類調整し各コロイド溶液に対するバリウム溶出
量を検討することとした。Colloid solution (platinum concentration: 200 ppm)
After adding 0.5 g (0.33 wt%) of ethylenediamminetetraacetic acid as a chelating agent to 150 mL, and further adding barium nitrate as a barium salt, a honeycomb carrier coated with alumina (alumina amount: 2.85 g)
Was immersed. In this case, the colloid solution is 500 p
pm, 1000 ppm, and the amount of barium nitrate added was changed to adjust two types, and the amount of barium eluted for each colloid solution was examined.
【００６０】担体へコロイド溶液を吸着させた後は、第
４実施形態と同様の処理により白金／ロジウム担持触媒
を製造した。After the colloid solution was adsorbed on the carrier, a platinum / rhodium supported catalyst was produced by the same treatment as in the fourth embodiment.
【００６１】実験例５：この触媒製造工程において、一
定時間毎に溶液をサンプリングしてコロイド溶液中のバ
リウム濃度を測定したところ、図３の結果を得た。図３
から、添加したバリウム濃度にかかわらず溶液中のバリ
ウム濃度は約１５００ｐｐｍで飽和していることがわか
る。従って、バリウム塩を添加することなしに担体をコ
ロイド溶液に浸漬した場合の担体からのバリウム溶出量
は１５００ｐｐｍであるのに対し、コロイド溶液にバリ
ウム塩を添加することで、添加量５００ｐｐｍで約１０
００ｐｐｍ、添加量１０００ｐｐｍで約５００ｐｐｍと
なり、コロイド溶液に予めバリウム塩を添加することで
担体からのバリウム溶出量を低減できるといえる。ま
た、このバリウム溶出量はバリウム塩の添加濃度が多け
れば多いほど低減できることがわかった。 Experimental Example 5 : In this catalyst manufacturing process, the barium concentration in the colloid solution was measured by sampling the solution at regular intervals, and the results shown in FIG. 3 were obtained. FIG.
From this, it can be seen that the barium concentration in the solution is saturated at about 1500 ppm regardless of the added barium concentration. Therefore, when the carrier is immersed in the colloid solution without adding the barium salt, the amount of barium eluted from the carrier is 1500 ppm, whereas by adding the barium salt to the colloid solution, about 10 ppm is obtained at the added amount of 500 ppm.
It is about 500 ppm when the amount is 00 ppm and the amount added is 1000 ppm, and it can be said that the amount of barium eluted from the carrier can be reduced by adding the barium salt to the colloid solution in advance. It was also found that the amount of barium eluted can be reduced as the concentration of the added barium salt increases.
【００６２】[0062]
【発明の効果】以上説明したように本発明は、保護剤を
含有するコロイド溶液を担体に吸着させる排ガス浄化触
媒触媒において、保護剤を従来のＰＶＰから４級アンモ
ニウム塩とするものである。本発明によれば、ＰＶＰを
添加したコロイド溶液よりも速やかにコロイド溶液を担
体に吸着させることができ、触媒の生産性を向上させる
ことができる。As described above, the present invention relates to an exhaust gas purifying catalyst in which a colloid solution containing a protective agent is adsorbed on a carrier, wherein the protective agent is changed from conventional PVP to a quaternary ammonium salt. ADVANTAGE OF THE INVENTION According to this invention, a colloid solution can be made to adsorb | suck a support | carrier more quickly than the colloid solution to which PVP was added, and the productivity of a catalyst can be improved.
【００６３】また、担体にバリウム等のアルカリ土類金
属が担持されている場合、本発明においては、コロイド
溶液にキレート剤を添加する。これにより、担体から溶
出するアルカリ土類金属の影響を受けることなく、効率
的にコロイド溶液を担体に吸着させることができる。そ
して、コロイド溶液にアルカリ土類金属塩を更に添加す
ることで、担体からのアルカリ土類金属の溶出を抑制
し、製造される触媒のＮＯｘ吸蔵特性を確保することが
できる。When the carrier supports an alkaline earth metal such as barium, a chelating agent is added to the colloid solution in the present invention. Thereby, the colloid solution can be efficiently adsorbed on the carrier without being affected by the alkaline earth metal eluted from the carrier. Further, by further adding an alkaline earth metal salt to the colloid solution, elution of the alkaline earth metal from the carrier can be suppressed, and the NOx storage characteristics of the produced catalyst can be secured.
【００６４】本発明により製造される触媒は、上記効果
により優れたＮＯｘ浄化特性を有し、かつ、ＰＶＰを用
いる場合と同様、貴金属粒子の粒成長が抑制され触媒特
性を長期間保持することができる。The catalyst produced according to the present invention has excellent NOx purification characteristics due to the above-mentioned effects, and can suppress the growth of noble metal particles and maintain the catalyst characteristics for a long period of time, as in the case of using PVP. it can.
【図１】第３実施形態及び比較例３の触媒製造過程にお
けるコロイド溶液中の白金濃度の変化を示す図。FIG. 1 is a diagram showing a change in the concentration of platinum in a colloid solution during a catalyst production process according to a third embodiment and Comparative Example 3.
【図２】第４実施形態の触媒製造過程におけるコロイド
溶液中の白金濃度の変化を示す図。FIG. 2 is a diagram showing a change in the concentration of platinum in a colloid solution during a catalyst manufacturing process according to a fourth embodiment.
【図３】第５実施形態の触媒製造過程におけるコロイド
溶液中のバリウム濃度の変化を示す図。FIG. 3 is a diagram showing a change in barium concentration in a colloid solution during a catalyst production process according to a fifth embodiment.
フロントページの続き (72)発明者 齋藤 昌幸 神奈川県平塚市新町２番73号 田中貴金属 工業株式会社技術開発センター内 (72)発明者 三好 直人 愛知県豊田市トヨタ町１番地 トヨタ自動 車株式会社内 Ｆターム(参考） 3G091 AA02 AB06 BA14 BA39 GB03W GB05W GB06W GB07W 4G069 AA03 AA08 BA01B BB05A BB10A BB12A BB16A BC08A BC13A BC32A BC33A BC69A BC70A BC71A BC71B BC72A BC73A BC74A BC75A BC75B BE13A BE13B BE17A BE17B CA03 CA08 CA13 DA06 EB19 FB06 FC02 Continued on the front page (72) Inventor Masayuki Saito 2-73, Shinmachi, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Development Center, Tanaka Kikinzoku Kogyo Co., Ltd. F-term (reference) 3G091 AA02 AB06 BA14 BA39 GB03W GB05W GB06W GB07W 4G069 AA03 AA08 BA01B BB05A BB10A BB12A BB16A BC08A BC13A BC32A BC33A BC69A BC70A BC71A BC71B BC72A BC73 BE13BCA13 BC13 BE13BCA13 BC75
Claims (12)
と有機溶媒との混合溶媒若しくは有機溶媒からなる溶媒
と、保護剤とを混合し、この混合溶液を還流し溶液中の
貴金属塩を還元することにより貴金属粒子が懸濁するコ
ロイド溶液を製造し、 前記コロイド溶液を多孔質体である担体に吸着させてな
る排ガス浄化触媒の製造方法において、 前記保護剤として４級アンモニウム塩を混合したコロイ
ド溶液を吸着させる排ガス浄化触媒の製造方法。1. A mixture of one or more noble metal salts, water or a mixed solvent of water and an organic solvent or a solvent comprising an organic solvent, and a protective agent. A method for producing a colloidal solution in which noble metal particles are suspended by reducing a noble metal salt, and a method for producing an exhaust gas purifying catalyst comprising adsorbing the colloidal solution on a porous carrier, wherein a quaternary ammonium salt is used as the protective agent A method for producing an exhaust gas purifying catalyst for adsorbing a colloidal solution containing a mixture thereof.
を少なくとも１つ有する４級アンモニウムを添加する請
求項１記載の排ガス浄化触媒の製造方法。2. The method for producing an exhaust gas purifying catalyst according to claim 1, wherein a quaternary ammonium having at least one alkyl group having 1 to 4 carbon atoms is added as a protective agent.
含有しない４級アンモニウム塩を添加する請求項１又は
請求項２記載の排ガス浄化触媒の製造方法。3. The method for producing an exhaust gas purifying catalyst according to claim 1, wherein a quaternary ammonium salt containing no sulfur and chlorine is added as the quaternary ammonium salt.
アンモニウム塩、テトラエチルアンモニウム塩、テトラ
−ｎ−プロピルアンモニウム塩、テトライソプロピルア
ンモニウム塩、テトラブチルアンモニウム塩、ベンジル
トリメチルアンモニウム塩を添加する請求項１〜請求項
３記載の排ガス浄化触媒の製造方法。4. A quaternary ammonium salt comprising a tetramethylammonium salt, a tetraethylammonium salt, a tetra-n-propylammonium salt, a tetraisopropylammonium salt, a tetrabutylammonium salt, and a benzyltrimethylammonium salt. Item 4. The method for producing an exhaust gas purifying catalyst according to Item 3.
酸塩、炭酸塩、硝酸塩、亜硝酸塩の少なくとも１種を添
加する請求項１〜請求項４記載の排ガス浄化触媒の製造
方法。5. The method for producing an exhaust gas purifying catalyst according to claim 1, wherein at least one of a hydroxide, an acetate, a carbonate, a nitrate and a nitrite is added as the quaternary ammonium salt.
前記コロイド溶液を担体に吸着させる請求項１〜請求項
５記載の排ガス浄化触媒の製造方法。6. A collating solution further comprising a chelating agent,
The method for producing an exhaust gas purifying catalyst according to claim 1, wherein the colloid solution is adsorbed on a carrier.
基を有する化合物を添加する請求項６記載の排ガス浄化
触媒の製造方法。7. The method for producing an exhaust gas purifying catalyst according to claim 6, wherein a compound having two or more carboxyl groups is added as a chelating agent.
酢酸を添加する請求項６記載の排ガス浄化触媒の製造方
法。8. The method for producing an exhaust gas purifying catalyst according to claim 6, wherein ethylenediamminetetraacetic acid is added as a chelating agent.
を添加し、前記コロイド溶液を担体に吸着させる請求項
６〜請求項８記載の排ガス浄化触媒の製造方法。9. The method for producing an exhaust gas purifying catalyst according to claim 6, wherein a salt of an alkaline earth metal is further added to the colloid solution, and the colloid solution is adsorbed on a carrier.
し、コロイド溶液を担体に吸着させる請求項１〜請求項
９記載の排ガス浄化触媒の製造方法。10. The method for producing an exhaust gas purifying catalyst according to claim 1, wherein the carrier is immersed in a tank containing the colloid solution, and the colloid solution is adsorbed on the carrier.
ム、ルテニウム、ロジウム、イリジウム、オスミウムの
塩である請求項１〜請求項１０記載の排ガス浄化触媒の
製造方法。11. The method according to claim 1, wherein the noble metal salt is a salt of platinum, gold, silver, palladium, ruthenium, rhodium, iridium, and osmium.
方法により製造される排ガス浄化触媒。12. An exhaust gas purifying catalyst produced by the method according to any one of claims 1 to 11.
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| EP3081296A4 (en) * | 2013-12-11 | 2017-08-09 | Cataler Corporation | Exhaust gas purifying catalyst |
| WO2016052746A1 (en) * | 2014-10-02 | 2016-04-07 | 株式会社キャタラー | Dispersion liquid of composite particles, and method for producing same |
| WO2016052728A1 (en) * | 2014-10-02 | 2016-04-07 | 株式会社キャタラー | Dispersion liquid of composite particles, and method for producing same |
| JPWO2016052728A1 (en) * | 2014-10-02 | 2017-07-27 | 株式会社キャタラー | Composite particle dispersion and method for producing the same |
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