JP2007253037A - Catalyst for cleaning exhaust gas and manufacturing method therefor - Google Patents

Catalyst for cleaning exhaust gas and manufacturing method therefor Download PDF

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JP2007253037A
JP2007253037A JP2006079102A JP2006079102A JP2007253037A JP 2007253037 A JP2007253037 A JP 2007253037A JP 2006079102 A JP2006079102 A JP 2006079102A JP 2006079102 A JP2006079102 A JP 2006079102A JP 2007253037 A JP2007253037 A JP 2007253037A
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particles
coating layer
slurry
noble metal
alumina
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Hiroto Kikuchi
博人 菊地
Masaki Nakamura
雅紀 中村
Hironori Wakamatsu
広憲 若松
Katsuo Suga
克雄 菅
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Nissan Motor Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for cleaning exhaust gas which can be manufactured through a simple process and can keep a high cleaning rate for a long period of time and to provide a manufacturing therefor. <P>SOLUTION: The catalyst 1 for cleaning exhaust gas comprises a noble metal particle 3 for causing a catalytic reaction while being in contact with exhaust gas, a first covering layer 5 for covering the periphery of the noble metal particle 3, a second covering layer 7 for covering the noble metal particle 3 and the first covering layer 5, and a base material on which the noble metal particle 3 is deposited. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、排気ガス浄化用触媒及びその製造方法に関する。 The present invention relates to an exhaust gas purification catalyst and a method for producing the same.

近年、自動車用の排出ガス規制は益々厳しくなる一方であり、排気ガス浄化用触媒には、排ガス中に含まれる有害な成分、例えば、未燃焼炭化水素（ＨＣ）や一酸化炭素（ＣＯ）の浄化をより高効率で行なうことが要求されている。排ガス浄化触媒は、アルミナ等の基材の表面に貴金属粒子３を担持したものであり、排ガス中に含まれる有害な成分、例えば未燃焼炭化水素（ＨＣ）や一酸化炭素（ＣＯ）を貴金属粒子で酸化し、無害な成分である水やガスに変換する。そして、一般に、触媒の浄化性能は貴金属粒子の表面積が大きいほど向上するため、貴金属粒子の粒径を小さくすることにより、貴金属粒子の表面積を大きくして表面エネルギーを増大させることが行われている。   In recent years, exhaust gas regulations for automobiles are becoming more and more stringent, and exhaust gas purification catalysts include harmful components contained in exhaust gas, such as unburned hydrocarbons (HC) and carbon monoxide (CO). There is a demand for more efficient purification. The exhaust gas purification catalyst is a catalyst in which noble metal particles 3 are supported on the surface of a substrate such as alumina, and harmful components contained in the exhaust gas, such as unburned hydrocarbon (HC) and carbon monoxide (CO), are precious metal particles. Oxidizes with water and gas, which is harmless. And generally, since the purification performance of the catalyst is improved as the surface area of the noble metal particles is increased, the surface energy is increased by increasing the surface area of the noble metal particles by reducing the particle size of the noble metal particles. .

ここで、排気ガス浄化用触媒の貴金属粒子は、初期段階では数ｎｍ以下の超微粒子状態になっている。しかし、高温の酸化雰囲気中に排気ガス浄化用触媒が晒されているうちに、貴金属粒子の表面が酸化され、近傍の貴金属粒子同士が合体して数十ｎｍに粗大化してしまい、貴金属粒子の表面積が低下して有害物質の浄化率が低下するという問題がある。   Here, the noble metal particles of the exhaust gas purifying catalyst are in an ultrafine particle state of several nm or less in the initial stage. However, while the exhaust gas purification catalyst is exposed to a high-temperature oxidizing atmosphere, the surface of the noble metal particles is oxidized, and the noble metal particles in the vicinity coalesce and become coarse to several tens of nanometers. There is a problem in that the surface area decreases and the purification rate of harmful substances decreases.

この貴金属粒子の粗大化による表面積低下を防止すべく、逆ミセル法などのような表面積の大きい貴金属粒子の製法に関する開発が進んでいる。この逆ミセル法とは、まず、有機溶媒中に界面活性剤と触媒活性な成分（例えば、貴金属元素）を含む水溶液とを混合する。その後、有機溶媒中に、貴金属を含む水溶液を含有する逆ミセルが形成されたエマルジョン溶液を調製し、貴金属を沈殿させた後、還元又は不溶化し、逆ミセルの中で微粒化した貴金属を析出させる方法である。   In order to prevent a decrease in the surface area due to the coarsening of the noble metal particles, development relating to a method for producing noble metal particles having a large surface area such as a reverse micelle method has been advanced. In the reverse micelle method, first, an aqueous solution containing a surfactant and a catalytically active component (for example, a noble metal element) is mixed in an organic solvent. Thereafter, an emulsion solution in which reverse micelles containing an aqueous solution containing a noble metal are formed in an organic solvent is prepared, and after precious metal is precipitated, it is reduced or insolubilized to precipitate the precious metal atomized in the reverse micelle. Is the method.

また、特開２０００−４２４１１号公報には、エマルジョン溶液調製工程において、逆ミセルの中に酸素吸蔵作用を有する元素を含有させて触媒を製造する方法が開示されている。この逆ミセル法では、エマルジョン溶液中に含まれる逆ミセルの中で、基材に触媒活性な成分を担持した後、逆ミセルを崩壊させて、得られた沈殿物を濾過、乾燥、粉砕、焼成する各工程を経て触媒としている。本製造方法を用いて製造された触媒は、基材に酸素吸蔵作用を有する元素を担持できるだけではなく、基材の最表面及び基材中に形成された孔部表面にも触媒活性な成分を担持するため、触媒の活性を高めることができる。   Japanese Patent Application Laid-Open No. 2000-42411 discloses a method for producing a catalyst by containing an element having an oxygen storage effect in reverse micelles in an emulsion solution preparation step. In this reverse micelle method, after supporting the catalytically active component on the base material in the reverse micelle contained in the emulsion solution, the reverse micelle is disintegrated, and the resulting precipitate is filtered, dried, pulverized, and calcined. Each step is used as a catalyst. The catalyst produced using this production method not only supports an element having an oxygen storage effect on the base material, but also has a catalytically active component on the outermost surface of the base material and the surface of the pores formed in the base material. Since it is supported, the activity of the catalyst can be increased.

特開２０００−４２４１１号公報JP 2000-42411 A

しかしながら、前述した逆ミセル法では、逆ミセルが形成されたエマルジョン溶液を噴霧焼成して触媒を製造するため、製造工程が複雑化して製造コストが上昇するという問題があった。   However, in the reverse micelle method described above, a catalyst is manufactured by spray firing the emulsion solution in which the reverse micelle is formed, so that the manufacturing process becomes complicated and the manufacturing cost increases.

そこで、本発明は、製造工程が簡易で、高い浄化率を長期間保持することができる排気ガス浄化用触媒及びその製造方法を提供することを目的とする。   Accordingly, an object of the present invention is to provide an exhaust gas purifying catalyst that has a simple manufacturing process and can maintain a high purification rate for a long period of time, and a method for manufacturing the same.

前記目的を達成するために、本発明に係る排気ガス浄化用触媒は、貴金属粒子と、該貴金属粒子を覆う第１の被覆層と、この第１の被覆層を覆う第２の被覆層とを備えてなる排気ガス浄化用触媒であって、前記第１の被覆層は、Ａｌ，Ｃｅ，Ｚｒ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉ単体又はこれらの酸化物から選択される群のうち、少なくともいずれかからなり、前記第２の被覆層は、アルミナ及びジルコニアの少なくともいずれかであることを特徴とする。   To achieve the above object, an exhaust gas purifying catalyst according to the present invention comprises noble metal particles, a first coating layer covering the noble metal particles, and a second coating layer covering the first coating layer. An exhaust gas purifying catalyst provided, wherein the first coating layer is at least one selected from the group consisting of Al, Ce, Zr, Mn, Co, Fe, Ni alone or an oxide thereof. And the second coating layer is at least one of alumina and zirconia.

また、本発明に係る排気ガス浄化用触媒の製造方法は、ガス中蒸発法を用いて、貴金属粒子を第１の被覆層で覆う工程と、該第１の被覆層を第２の被覆層で覆う工程とを含み、
前記第１の被覆層は、Ａｌ，Ｃｅ，Ｚｒ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉ又はこれらの酸化物から選択される少なくともいずれかからなり、前記第２の被覆層は、アルミナ及びジルコニアの少なくともいずれかからなることを特徴とする。 The method for producing an exhaust gas purifying catalyst according to the present invention includes a step of covering noble metal particles with a first coating layer using an in-gas evaporation method, and the first coating layer with a second coating layer. Covering the process,
The first coating layer is made of at least one selected from Al, Ce, Zr, Mn, Co, Fe, Ni or oxides thereof, and the second coating layer is at least one of alumina and zirconia. It consists of these.

本発明に係る排気ガス浄化用触媒によれば、貴金属粒子の周囲を第１の被覆層によって覆い、さらに、これらの貴金属粒子及び第１の被覆層を第２の被覆層によって覆っているため、基材上における貴金属粒子の移動による凝集化を抑制することができ、貴金属の表面積を大きい状態に保持することができる。   According to the exhaust gas purification catalyst of the present invention, the periphery of the noble metal particles is covered with the first coating layer, and further, the noble metal particles and the first coating layer are covered with the second coating layer, Aggregation due to movement of the noble metal particles on the substrate can be suppressed, and the surface area of the noble metal can be maintained in a large state.

また、本発明に係る排気ガス浄化用触媒の製造方法によれば、貴金属粒子の周囲を第１の被覆層及び第２の被覆層を介して覆った触媒を効率的に製造することができる。従って、長期間使用した後においても、貴金属粒子同士が凝集せずに大きい表面積を保持することができるため、高い浄化性能を保つことができる。   Moreover, according to the method for producing an exhaust gas purifying catalyst according to the present invention, a catalyst in which the periphery of the noble metal particles is covered with the first coating layer and the second coating layer can be efficiently produced. Therefore, even after a long period of use, since a large surface area can be maintained without agglomeration of noble metal particles, high purification performance can be maintained.

以下、本発明の実施形態を図面に基づき説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

［触媒］
図１は、本発明に係る排気ガス浄化用触媒の表面の状態を拡大して示す概略図である。 [catalyst]
FIG. 1 is an enlarged schematic view showing the state of the surface of an exhaust gas purifying catalyst according to the present invention.

図１に示すように、本発明に係る排気ガス浄化用触媒１は、排気ガスに接触して有害成分を浄化させる活性金属である貴金属粒子３と、該貴金属粒子３の外周を覆う第１の被覆層５と、該第１の被覆層５及び貴金属粒子３を内包する第２の被覆層７とを備えている。   As shown in FIG. 1, an exhaust gas purifying catalyst 1 according to the present invention includes a noble metal particle 3 that is an active metal that contacts exhaust gas to purify harmful components, and a first covering the outer periphery of the noble metal particle 3. A coating layer 5 and a second coating layer 7 containing the first coating layer 5 and the noble metal particles 3 are provided.

貴金属粒子３の周囲を第１の被覆層５を介して第２の被覆層７で覆うことにより、貴金属粒子３の移動及び凝集を抑制することができると共に、第１の被覆層５及び第２の被覆層７を構成する粒子自体の凝集をも抑制できる。従って、触媒１が排気ガスに晒された後における貴金属粒子３の群からなる貴金属層の表面積が低下することを好適に抑制することができる。   By covering the periphery of the noble metal particles 3 with the second coating layer 7 via the first coating layer 5, the movement and aggregation of the noble metal particles 3 can be suppressed, and the first coating layer 5 and the second coating layer 2 can be prevented. Aggregation of the particles constituting the coating layer 7 can also be suppressed. Therefore, the surface area of the noble metal layer composed of the group of noble metal particles 3 after the catalyst 1 is exposed to the exhaust gas can be suitably suppressed.

［貴金属粒子］
貴金属粒子３は、白金（Ｐｔ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）から選択される少なくともいずれかからなることが好ましい。 [Precious metal particles]
The noble metal particles 3 are preferably made of at least one selected from platinum (Pt), palladium (Pd), and rhodium (Rh).

貴金属粒子３の粒子径は、１ｎｍ〜５ｎｍが好ましい。粒子径が１ｎｍ未満では、第１の被覆層５による貴金属粒子３の移動を抑制する効果が低下してしまい、粒子径が５ｎｍよりも大きいと、複数の貴金属粒子３からなる貴金属層全体の表面積が低下し、触媒１としての性能が低下してしまう。   The particle diameter of the noble metal particles 3 is preferably 1 nm to 5 nm. If the particle diameter is less than 1 nm, the effect of suppressing the movement of the noble metal particles 3 by the first coating layer 5 is reduced. If the particle diameter is larger than 5 nm, the surface area of the entire noble metal layer composed of a plurality of noble metal particles 3 is reduced. Decreases, and the performance as the catalyst 1 decreases.

［第１の被覆層］
前記第１の被覆層５は、Ａｌ，Ｃｅ，Ｚｒ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉの単体又はこれらの酸化物からなる層であり、その平均厚さは、２０ｎｍ以下であることが好ましい。この平均厚さｔは、図１に示すように、貴金属粒子３の外周と、第１の被覆層５を構成する粒子のうち最も外周側に配置されたものの外周との距離を示す。 [First coating layer]
The first coating layer 5 is a layer made of a single substance of Al, Ce, Zr, Mn, Co, Fe, or Ni or an oxide thereof, and the average thickness thereof is preferably 20 nm or less. As shown in FIG. 1, the average thickness t indicates the distance between the outer periphery of the noble metal particles 3 and the outer periphery of the particles constituting the first coating layer 5 arranged on the outermost side.

第１の被覆層５の厚さが２０ｎｍより厚い場合は、貴金属粒子３に対して排気ガスが十分に行き渡らないため、ガス拡散が低下し、触媒活性効果が低下する。   When the thickness of the first coating layer 5 is greater than 20 nm, the exhaust gas does not reach the noble metal particles 3 sufficiently, so that the gas diffusion decreases and the catalytic activity effect decreases.

また、貴金属粒子３の近傍に、Ｃｅ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉ等を配置できるので、助触媒の効果を得ることもできる。   Moreover, since Ce, Mn, Co, Fe, Ni, etc. can be arrange | positioned in the vicinity of the noble metal particle 3, the effect of a promoter can also be acquired.

なお、第１の被覆層５は、Ａｌ等の粒子を複数集合させたクラスターから形成することが好ましい。   The first coating layer 5 is preferably formed from a cluster in which a plurality of particles such as Al are assembled.

［第２の被覆層］
第２の被覆層７は、アルミナとジルコニアのうち、少なくともいずれかからなる粒子によって形成している。この第２の被覆層７は、例えば、貴金属粒子３を第１の被覆層５によって被覆した粉末にアルミナ又はジルコニアを加えてスラリとし、ハニカム担体に塗布及び乾燥させることによって形成することができる。 [Second coating layer]
The second coating layer 7 is formed by particles made of at least one of alumina and zirconia. The second coating layer 7 can be formed, for example, by adding alumina or zirconia to a powder obtained by coating the noble metal particles 3 with the first coating layer 5 to form a slurry, and applying and drying the slurry on a honeycomb carrier.

［基材］
基材は、アルミナ（Ａｌ２Ｏ３）、セリア（ＣｅＯ２）、ジルコニア（ＺｒＯ２）、マグネシア（ＭｇＯ）、シリカ（ＳｉＯ２）、ＴｉＯ２、シリカアルミナ、酸化バナジウム及び酸化タングステンの群から選択される一又は二以上の元素からなる多孔質酸化物を好適に用いることができる。 [Base material]
The substrate is selected from the group consisting of alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ), magnesia (MgO), silica (SiO 2 ), TiO 2 , silica alumina, vanadium oxide and tungsten oxide. A porous oxide composed of one or two or more elements can be suitably used.

[触媒の製造装置]
図２は、真空蒸着装置の概要を示す概略図である。 [Catalyst production equipment]
FIG. 2 is a schematic view showing an outline of a vacuum deposition apparatus.

この真空蒸着装置１１は、外気から遮蔽された密閉性を有する真空槽１３と、該真空槽１３の内部に収容された抵抗加熱ボート（蒸発源）１５，１７及び冷却手段２９とを備えている。   The vacuum deposition apparatus 11 includes a vacuum chamber 13 having a sealing property shielded from the outside air, resistance heating boats (evaporation sources) 15 and 17 and a cooling unit 29 accommodated in the vacuum chamber 13. .

前記真空槽１３の下端部には、開閉自在に構成された酸素（Ｏ２）ガス導入口１９及びヘリウム（Ｈｅ）ガス導入口２１が設けられている。また、真空槽１３の高さ方向中央部には、試料投入口２３及び試料回収口２５が配設されており、真空槽１３の上部には、排気口２７が設けられている。 An oxygen (O 2 ) gas introduction port 19 and a helium (He) gas introduction port 21 configured to be openable and closable are provided at the lower end of the vacuum chamber 13. In addition, a sample insertion port 23 and a sample recovery port 25 are provided at the center of the vacuum chamber 13 in the height direction, and an exhaust port 27 is provided at the top of the vacuum chamber 13.

そして、抵抗加熱ボート１５，１７は、上下に間隔をおいて２つ配置されており、それぞれの抵抗加熱ボート１５，１７の上面は、湾曲して凹部に形成されている。   And two resistance heating boats 15 and 17 are arrange | positioned at intervals up and down, and the upper surface of each resistance heating boat 15 and 17 is curving and formed in the recessed part.

さらに、冷却手段２９は、液体窒素（Ｎ２）を用いて冷却するものであり、液体窒素導入口３１を真空槽１３を貫通して上方に延設し、この液体窒素導入口３１に冷却板３３を接続すると共に、該冷却板３３の下部に試料回収皿３５を配置している。 Further, the cooling means 29 is cooled by using liquid nitrogen (N 2 ), and the liquid nitrogen inlet 31 extends upward through the vacuum chamber 13, and a cooling plate is connected to the liquid nitrogen inlet 31. 33 is connected, and a sample collection tray 35 is disposed below the cooling plate 33.

［触媒の製造方法］
前記触媒１の製造方法を図３を用いて簡単に説明する。 [Method for producing catalyst]
A method for producing the catalyst 1 will be briefly described with reference to FIG.

まず、ガス中蒸発法によって貴金属粒子３を蒸発させ、この蒸発した貴金属粒子３を核として、別に蒸発させたＡｌ，Ｃｅ，Ｚｒ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉ等のクラスターを貴金属粒子３の周囲に成長させることにより、貴金属粒子３を第１の被覆層５によって被覆する。なお、前記クラスターを酸化させることにより、第１の被覆層５を酸化物粒子のクラスターとすることが出来る。   First, the noble metal particles 3 are evaporated by an in-gas evaporation method, and the clusters of Al, Ce, Zr, Mn, Co, Fe, Ni, etc., separately evaporated around the noble metal particles 3 around the noble metal particles 3 The noble metal particles 3 are covered with the first coating layer 5 by growing the noble metal particles 3. In addition, the 1st coating layer 5 can be made into the cluster of an oxide particle by oxidizing the said cluster.

例えば、真空蒸着装置１１の内部に、貴金属粒子３及び第１の被覆層５となる原料を収容し、真空槽内の圧力を所定値に保持し、前記原料を加熱してガス中蒸発法を用いて蒸発させることにより、貴金属を蒸発させる。また、この貴金属粒子３を核として別に蒸発させて得られるクラスターを貴金属粒子３の周囲に成長させることにより、貴金属粒子３を第１の被覆層５によって被覆する。   For example, the raw material to be used as the noble metal particles 3 and the first coating layer 5 is accommodated in the vacuum deposition apparatus 11, the pressure in the vacuum chamber is maintained at a predetermined value, and the raw material is heated to perform a gas evaporation method Use and evaporate to evaporate the noble metal. Further, the noble metal particles 3 are covered with the first coating layer 5 by growing clusters obtained by separately evaporating the noble metal particles 3 as nuclei around the noble metal particles 3.

次いで、前記第１の被覆層５の周囲に第２の被覆層７を形成する。例えば、貴金属粒子３を第１の被覆層５によって被覆した粉末にアルミナ又はジルコニアを加えてスラリとし、ハニカム担体に塗布及び乾燥させることによって、触媒１を作製する。   Next, a second coating layer 7 is formed around the first coating layer 5. For example, the catalyst 1 is produced by adding alumina or zirconia to a powder obtained by coating the noble metal particles 3 with the first coating layer 5 to form a slurry, and applying and drying to a honeycomb carrier.

次いで、実施例によって本発明の実施形態を更に具体的に説明する。なお、各実施例及び比較例における詳細な内容を表１にまとめて示す。

Figure 2007253037
Next, embodiments of the present invention will be described more specifically by way of examples. The detailed contents of each example and comparative example are summarized in Table 1.
Figure 2007253037

Ｐｔ粒子Ａの調製（Ｐｔ粒子径：１ｎｍ、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：２．５ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法（ガス中蒸発法）により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ａを調整した。 Preparation of Pt particles A (Pt particle diameter: 1 nm, thickness of first coating layer made of CeO 2 particles: 2.5 nm)
Using the vacuum vapor deposition apparatus 11 shown in FIG. 2, Pt particles A in which the Pt particles were covered with the first coating layer were prepared by vacuum vapor deposition (gas evaporation method).

具体的には、Ｐｔ粒子の粒子径は１ｎｍ〜５ｎｍであり、第１の被覆層はＣｅＯ２粒子からなり、層厚が２．５ｎｍであった。 Specifically, the particle diameter of the Pt particles was 1 nm to 5 nm, the first coating layer was made of CeO 2 particles, and the layer thickness was 2.5 nm.

まず、図２に示す真空槽１３内に配置した抵抗加熱ボート（蒸発源）１５の上にＰｔ原料を載置し、抵抗加熱ボート（蒸発源）１７の上にＣｅ原料を載置した。なお、抵抗加熱ボート１５は、抵抗加熱ボート１７よりも低い位置に配置している。抵抗加熱ボート１５と１７の高さ方向（上下方向）の距離をＸとした。   First, a Pt material was placed on a resistance heating boat (evaporation source) 15 disposed in the vacuum chamber 13 shown in FIG. 2, and a Ce material was placed on a resistance heating boat (evaporation source) 17. The resistance heating boat 15 is arranged at a position lower than the resistance heating boat 17. The distance in the height direction (vertical direction) of the resistance heating boats 15 and 17 is X.

次に、図示しない真空ポンプにより５．０×１０−８Ｔｏｒｒにまで真空槽１３内を排気した後、真空槽１３内に酸素ガスとヘリウムガスとを導入して１Ｔｏｒｒ付近とした。この時の酸素分圧は４０ｍｏｌ％であり、真空ポンプを作動させて一定のガス圧を保ち、液体Ｎ２導入口３１を介して液体窒素を導入し、冷却板３３を冷却した。 Next, the inside of the vacuum chamber 13 was evacuated to 5.0 × 10 −8 Torr by a vacuum pump (not shown), and then oxygen gas and helium gas were introduced into the vacuum chamber 13 to make it around 1 Torr. The oxygen partial pressure at this time was 40 mol%, the vacuum pump was operated to maintain a constant gas pressure, liquid nitrogen was introduced through the liquid N 2 inlet 31, and the cooling plate 33 was cooled.

また、抵抗加熱ボート１７と冷却板３３の高さ方向の距離をＹとした。 その後、抵抗加熱ボート１５，１７でＰｔとＣｅとを同時に蒸発させて、真空槽１３内に導入した酸素によりＣｅを酸化した。   The distance in the height direction between the resistance heating boat 17 and the cooling plate 33 is Y. Thereafter, Pt and Ce were evaporated at the same time by the resistance heating boats 15 and 17, and Ce was oxidized by oxygen introduced into the vacuum chamber 13.

抵抗加熱ボート１５に載置したＰｔは先に凝縮し、この凝縮により生成したＰｔ粒子にＣｅＯ２が被覆された。このＣｅＯ２が被覆されたＰｔ粒子は冷却板３３に付着するので、このＰｔ粒子を掻き落としてＰｔ粒子をＣｅＯ２で内包したＰｔ粒子Ａを得た。 Pt placed on the resistance heating boat 15 was condensed first, and CeO 2 was coated on the Pt particles generated by this condensation. Since the Pt particles coated with CeO 2 adhere to the cooling plate 33, the Pt particles are scraped off to obtain Pt particles A enclosing the Pt particles with CeO 2 .

このＰｔ粒子ＡをＴＥＭで観察したところ、Ｐｔ粒子Ａの粒径は１ｎｍ程度であり、ＣｅＯ２層の厚さは２．５ｎｍ程度であった。このＰｔ粒子ＡをＩＣＰ分析したところ、Ｐｔが３．４ｗｔ％含有されていた。 When the Pt particles A were observed with a TEM, the particle size of the Pt particles A was about 1 nm, and the thickness of the CeO 2 layer was about 2.5 nm. When this Pt particle A was analyzed by ICP, it was found to contain 3.4 wt% Pt.

Ｐｔ粒子Ｂの調製（Ｐｔ粒子径：１ｎｍ、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：３．５ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｂを調整した。このＰｔ粒子径は１ｎｍであり、第１の被覆層の厚さを３．５ｎｍとした。 Preparation of Pt particles B (Pt particle diameter: 1 nm, thickness of first coating layer made of CeO 2 particles: 3.5 nm)
The Pt particles B in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method using the vacuum vapor deposition apparatus 11 shown in FIG. The Pt particle diameter was 1 nm, and the thickness of the first coating layer was 3.5 nm.

図２に示す真空槽１３内の抵抗加熱ボート（蒸発源）１５にＰｔ、抵抗加熱ボート（蒸発源）１７にＣｅを各々セットした。なお、抵抗加熱ボート１５は、抵抗加熱ボート１７よりも低い位置に配置した。抵抗加熱ボート１５と抵抗加熱ボート１７との高さ方向の距離をＸとした。   Pt was set in the resistance heating boat (evaporation source) 15 and Ce was set in the resistance heating boat (evaporation source) 17 in the vacuum chamber 13 shown in FIG. The resistance heating boat 15 was arranged at a position lower than the resistance heating boat 17. The distance in the height direction between the resistance heating boat 15 and the resistance heating boat 17 is X.

次に、図示しない真空ポンプにより５．０×１０−８Ｔｏｒｒにまで真空槽内を排気した後、真空槽内に酸素ガスとヘリウムガスとを導入して１Ｔｏｒｒ付近とした。このときの酸素分圧は４０ｍｏｌ％であり、真空ポンプを作動させて一定のガス圧を保ち、液体Ｎ２導入口３１を介して液体窒素を導入し、冷却板３３を冷却した。 Next, the inside of the vacuum chamber was evacuated to 5.0 × 10 −8 Torr with a vacuum pump (not shown), and then oxygen gas and helium gas were introduced into the vacuum chamber to make it around 1 Torr. The oxygen partial pressure at this time was 40 mol%, the vacuum pump was operated to maintain a constant gas pressure, liquid nitrogen was introduced through the liquid N 2 inlet 31, and the cooling plate 33 was cooled.

抵抗加熱ボート１７と冷却板３３の高さ方向の距離を１．５Ｙとした。 その後、抵抗加熱ボート１５，１７でＰｔとＣｅとを同時に蒸発させて、真空槽１３内に導入した酸素によりＣｅを酸化した。   The distance in the height direction between the resistance heating boat 17 and the cooling plate 33 was 1.5Y. Thereafter, Pt and Ce were evaporated at the same time by the resistance heating boats 15 and 17, and Ce was oxidized by oxygen introduced into the vacuum chamber 13.

抵抗加熱ボート１５のＰｔは先に凝縮し、凝縮により生成したＰｔ粒子にＣｅＯ２が被覆された。ＣｅＯ２が被覆されたＰｔ粒子Ｂは、冷却板３３に付着するので、この粒子を掻き落としてＰｔ粒子Ｂを得た。 Pt of the resistance heating boat 15 was condensed first, and CeO 2 was coated on the Pt particles generated by the condensation. Since Pt particles B coated with CeO 2 adhere to the cooling plate 33, the particles were scraped off to obtain Pt particles B.

このＰｔ粒子ＢをＴＥＭで観察したところ、Ｐｔ粒子の粒径は１ｎｍ程度であり、ＣｅＯ２層の厚さは３．５ｎｍ程度であった。このＰｔ粒子ＢをＩＣＰ分析したところ、Ｐｔが１．３ｗｔ％含有されていた。 When the Pt particles B were observed with a TEM, the particle size of the Pt particles was about 1 nm, and the thickness of the CeO 2 layer was about 3.5 nm. When this Pt particle B was analyzed by ICP, 1.3 wt% of Pt was contained.

Ｐｔ粒子Ｃの調製（Ｐｔ粒子径：２ｎｍ、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：５ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｃを調整した。このＰｔ粒子径は２ｎｍであり、第１の被覆層を構成するＣｅＯ２の粒子径を５ｎｍとした。このＰｔ粒子ＣをＩＣＰ分析したところ、Ｐｔが３．４ｗｔ％含有されていた。 Preparation of Pt particles C (Pt particle diameter: 2 nm, thickness of first coating layer made of CeO 2 particles: 5 nm)
Using the vacuum vapor deposition apparatus 11 shown in FIG. 2, the Pt particles C in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method. The Pt particle diameter was 2 nm, and the particle diameter of CeO 2 constituting the first coating layer was 5 nm. As a result of ICP analysis of the Pt particles C, 3.4 wt% of Pt was contained.

Ｐｔ粒子Ｄの調製（Ｐｔ粒子径：２ｎｍ、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：７．５ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｄを調整した。このＰｔ粒子径は２ｎｍであり、ＣｅＯ２粒子からなる第１の被覆層の厚さを７．５ｎｍとした。 Preparation of Pt particles D (Pt particle diameter: 2 nm, thickness of first coating layer made of CeO 2 particles: 7.5 nm)
The Pt particles D in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method using the vacuum vapor deposition apparatus 11 shown in FIG. The Pt particle diameter was 2 nm, and the thickness of the first coating layer made of CeO 2 particles was 7.5 nm.

抵抗加熱ボート１５と抵抗加熱ボート１７との高さ方向の距離を１．５Ｘとし、抵抗加熱ボート１７と冷却板３３の高さ方向の距離を３Ｙとした。このＰｔ粒子ＤをＴＥＭで観察したところ、Ｐｔ粒子の粒径は２ｎｍ程度であり、ＣｅＯ２粒子からなる第１の被覆層の厚さは７．５ｎｍ程度であった。このＰｔ粒子ＤをＩＣＰ分析したところ、Ｐｔが１．１ｗｔ％含有されていた。 The distance in the height direction between the resistance heating boat 15 and the resistance heating boat 17 was 1.5X, and the distance in the height direction between the resistance heating boat 17 and the cooling plate 33 was 3Y. When the Pt particles D were observed with a TEM, the particle diameter of the Pt particles was about 2 nm, and the thickness of the first coating layer made of CeO 2 particles was about 7.5 nm. As a result of ICP analysis of the Pt particles D, 1.1 wt% of Pt was contained.

Ｐｔ粒子Ｅの調製（Ｐｔ粒子径：３ｎｍ 、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：１０ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｅを調整した。このＰｔ粒子径は３ｎｍであり、ＣｅＯ２粒子からなる第１の被覆層の厚さを１０ｎｍとした。 Preparation of Pt particles E (Pt particle diameter: 3 nm, thickness of first coating layer made of CeO 2 particles: 10 nm)
Using the vacuum vapor deposition apparatus 11 shown in FIG. 2, Pt particles E in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method. The Pt particle diameter was 3 nm, and the thickness of the first coating layer made of CeO 2 particles was 10 nm.

抵抗加熱ボート１５と抵抗加熱ボート１７との高さ方向の距離を２Ｘとし、抵抗加熱ボート１７と冷却板３３の高さ方向の距離を４Ｙとした。   The distance in the height direction between the resistance heating boat 15 and the resistance heating boat 17 was 2X, and the distance in the height direction between the resistance heating boat 17 and the cooling plate 33 was 4Y.

このＰｔ粒子ＥをＴＥＭで観察したところ、Ｐｔ粒子の粒径は３ｎｍ程度であり、ＣｅＯ２粒子からなる第１の被覆層の厚さは１０ｎｍ程度であった。このＰｔ粒子ＥをＩＣＰ分析したところ、Ｐｔが１．５ｗｔ％含有されていた。 When this Pt particle E was observed by TEM, the particle size of the Pt particle was about 3 nm, and the thickness of the first coating layer made of CeO 2 particles was about 10 nm. As a result of ICP analysis of the Pt particles E, 1.5 wt% of Pt was contained.

Ｐｔ粒子Ｆの調製（Ｐｔ粒子径：３ｎｍ 、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：１２．５ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｆを調整した。抵抗加熱ボート１５と抵抗加熱ボート１７との高さ方向の距離を２Ｘとし、抵抗加熱ボート１７と冷却板３３の高さ方向の距離を５Ｙとした。 Preparation of Pt particles F (Pt particle diameter: 3 nm, thickness of first coating layer made of CeO 2 particles: 12.5 nm)
Using the vacuum vapor deposition apparatus 11 shown in FIG. 2, Pt particles F in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method. The distance in the height direction between the resistance heating boat 15 and the resistance heating boat 17 is 2X, and the distance in the height direction between the resistance heating boat 17 and the cooling plate 33 is 5Y.

このＰｔ粒子径は３ｎｍであり、ＣｅＯ２粒子からなる第１の被覆層の厚さを１２．５ｎｍとした。 The Pt particle diameter was 3 nm, and the thickness of the first coating layer made of CeO 2 particles was 12.5 nm.

このＰｔ粒子ＦをＩＣＰ分析したところ、Ｐｔが０．７７ｗｔ％含有されていた。   ICP analysis of the Pt particles F revealed that Pt was contained at 0.77 wt%.

Ｐｔ粒子Ｇの調製（Ｐｔ粒子径：５ｎｍ 、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：１５ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｆを調整した。抵抗加熱ボート１５と抵抗加熱ボート１７との高さ方向の距離を３Ｘとし、抵抗加熱ボート１７と冷却板３３の高さ方向の距離を６Ｙとした。このＰｔ粒子径は５ｎｍであり、ＣｅＯ２粒子からなる第１の被覆層の厚さを１５ｎｍとした。このＰｔ粒子ＧをＩＣＰ分析したところ、Ｐｔが１．９９ｗｔ％含有されていた。 Preparation of Pt particles G (Pt particle diameter: 5 nm, thickness of first coating layer made of CeO 2 particles: 15 nm)
Using the vacuum vapor deposition apparatus 11 shown in FIG. 2, Pt particles F in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method. The distance in the height direction between the resistance heating boat 15 and the resistance heating boat 17 is 3X, and the distance in the height direction between the resistance heating boat 17 and the cooling plate 33 is 6Y. The Pt particle diameter was 5 nm, and the thickness of the first coating layer made of CeO 2 particles was 15 nm. When this Pt particle G was analyzed by ICP, it contained 1.99 wt% of Pt.

Ｐｔ粒子Ｈの調製（Ｐｔ粒子径：５ｎｍ 、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：２０ｎｍ）
図２に示す真空蒸着装置１１を用いて、真空蒸着法により、Ｐｔ粒子を第１の被覆層で覆ったＰｔ粒子Ｈを調整した。抵抗加熱ボート１５と抵抗加熱ボート１７との高さ方向の距離を３Ｘとし、抵抗加熱ボート１７と冷却板３３の高さ方向の距離を７Ｙとした。このＰｔ粒子ＨをＴＥＭで観察したところ、Ｐｔ粒子Ｈの粒径は５ｎｍ程度であり、ＣｅＯ２粒子からなる第１の被覆層の厚さは２０ｎｍ程度であった。このＰｔ粒子ＨをＩＣＰ分析したところ、Ｐｔが０．８５ｗｔ％含有されていた。 Preparation of Pt particles H (Pt particle diameter: 5 nm, thickness of first coating layer made of CeO 2 particles: 20 nm)
The Pt particles H in which the Pt particles were covered with the first coating layer were prepared by a vacuum vapor deposition method using the vacuum vapor deposition apparatus 11 shown in FIG. The distance in the height direction between the resistance heating boat 15 and the resistance heating boat 17 was 3X, and the distance in the height direction between the resistance heating boat 17 and the cooling plate 33 was 7Y. When the Pt particles H were observed with a TEM, the particle size of the Pt particles H was about 5 nm, and the thickness of the first coating layer made of CeO 2 particles was about 20 nm. As a result of ICP analysis of the Pt particles H, 0.85 wt% Pt was contained.

Ｐｄ粒子Ｉの調製（Ｐｄ粒子径：２ｎｍ、ＣｅＯ ２ 粒子からなる第１の被覆層の厚さ：５ｎｍ）
図２に示す真空槽内の抵抗加熱ボート（蒸発源）１５にＰｄ、抵抗加熱ボート（蒸発源）１７にＣｅを各々セットした。なお、抵抗加熱ボート１５は、抵抗加熱ボート１７よりも低い位置に配置している。蒸発源１５と１７の高さ方向の距離をＶとした。 Preparation of Pd particles I (Pd particle diameter: 2 nm, thickness of first coating layer made of CeO 2 particles: 5 nm)
Pd was set in the resistance heating boat (evaporation source) 15 and Ce was set in the resistance heating boat (evaporation source) 17 in the vacuum chamber shown in FIG. The resistance heating boat 15 is arranged at a position lower than the resistance heating boat 17. The distance in the height direction between the evaporation sources 15 and 17 was defined as V.

次に、図示しない真空ポンプにより５．０×１０−８Ｔｏｒｒにまで真空槽内を排気した後、真空槽内に酸素ガスとヘリウムガスとを導入して１Ｔｏｒｒ付近とした。このときの酸素分圧は４０ｍｏｌ％であり、真空ポンプを作動させて一定のガス圧を保ち、液体Ｎ２導入口３１を介して液体窒素を導入し、冷却板３３を冷却した。 Next, the inside of the vacuum chamber was evacuated to 5.0 × 10 −8 Torr with a vacuum pump (not shown), and then oxygen gas and helium gas were introduced into the vacuum chamber to make it around 1 Torr. The oxygen partial pressure at this time was 40 mol%, the vacuum pump was operated to maintain a constant gas pressure, liquid nitrogen was introduced through the liquid N 2 inlet 31, and the cooling plate 33 was cooled.

抵抗加熱ボート１７と冷却板３３の高さ方向の距離をＷとした。 その後、抵抗加熱ボート１５，１７でＰｄとＣｅとを同時に蒸発させて、真空槽１３内に導入した酸素によりＣｅを酸化した。   The distance in the height direction between the resistance heating boat 17 and the cooling plate 33 is W. Thereafter, Pd and Ce were evaporated at the same time by the resistance heating boats 15 and 17, and Ce was oxidized by oxygen introduced into the vacuum chamber 13.

抵抗加熱ボート１５のＰｄは先に凝縮し、凝縮により生成したＰｄ粒子にＣｅＯ２粒子が被覆された。このＣｅＯ２が被覆されたＰｄ粒子は冷却板３３に付着するので、この粒子を掻き落としてＰｄ粒子Ｉを得た。 Pd of the resistance heating boat 15 was condensed first, and CeO 2 particles were coated on the Pd particles generated by the condensation. Since the Pd particles coated with CeO 2 adhere to the cooling plate 33, the particles were scraped off to obtain Pd particles I.

このＰｄ粒子ＩをＴＥＭで観察したところ、Ｐｔ粒子の粒径は２ｎｍ程度であり、ＣｅＯ２層の厚さは５ｎｍ程度であった。このＰｄ粒子ＩをＩＣＰ分析したところ、Ｐｔが１．９４ｗｔ％含有されていた。 When this Pd particle I was observed with a TEM, the particle size of the Pt particle was about 2 nm, and the thickness of the CeO 2 layer was about 5 nm. When this Pd particle I was analyzed by ICP, it contained 1.94 wt% of Pt.

Ｒｈ粒子Ｊの調製（Ｒｈ粒子径：２ｎｍ、ＺｒＯ ２ 粒子からなる第１の被覆層の厚さ：５ｎｍ）
図２に示す真空槽１３内の抵抗加熱ボート（蒸発源）１５にＲｈを載置し、抵抗加熱ボート（蒸発源）１７にＺｒを載置した。なお、抵抗加熱ボート１５は、抵抗加熱ボート１７よりも低い位置に配置した。また、抵抗加熱ボート１５，１７の高さ方向の距離をＴとした。 Preparation of Rh particles J (Rh particle diameter: 2 nm, thickness of first coating layer made of ZrO 2 particles: 5 nm)
Rh was placed on a resistance heating boat (evaporation source) 15 in the vacuum tank 13 shown in FIG. 2, and Zr was placed on a resistance heating boat (evaporation source) 17. The resistance heating boat 15 was arranged at a position lower than the resistance heating boat 17. The distance in the height direction of the resistance heating boats 15 and 17 was T.

次に、図示しない真空ポンプにより５．０×１０−８Ｔｏｒｒにまで排気した後、真空槽内に酸素ガスとヘリウムガスとを導入して１Ｔｏｒｒ付近とした。このときの酸素分圧は４０ｍｏｌ％であり、真空ポンプを作動させて一定のガス圧を保ち、液体Ｎ２導入口３１を介して液体窒素を導入し、冷却板３３を冷却した。 Next, after evacuating to 5.0 × 10 −8 Torr by a vacuum pump (not shown), oxygen gas and helium gas were introduced into the vacuum chamber to make it around 1 Torr. The oxygen partial pressure at this time was 40 mol%, the vacuum pump was operated to maintain a constant gas pressure, liquid nitrogen was introduced through the liquid N 2 inlet 31, and the cooling plate 33 was cooled.

抵抗加熱ボート１７と冷却板３３の高さ方向の距離をＵとした。 その後、抵抗加熱ボート１５，１７でＲｈとＺｒとを同時に蒸発させて、真空槽内に導入した酸素によりＺｒを酸化した。   The distance in the height direction between the resistance heating boat 17 and the cooling plate 33 is U. Thereafter, Rh and Zr were simultaneously evaporated by the resistance heating boats 15 and 17, and Zr was oxidized by oxygen introduced into the vacuum chamber.

抵抗加熱ボート１５のＲｈは先に凝縮し、凝縮により生成したＲｈ粒子にＺｒＯ２粒子が被覆された。ＺｒＯ２が被覆されたＲｈ粒子は冷却板３３に付着するので、この粒子を掻き落としてＲｈ粒子Ｊを得た。 The Rh of the resistance heating boat 15 was condensed first, and the Rh particles generated by the condensation were coated with ZrO 2 particles. Since the Rh particles coated with ZrO 2 adhere to the cooling plate 33, the particles were scraped off to obtain Rh particles J.

このＲｈ粒子ＪをＴＥＭで観察したところ、Ｒｈ粒子の粒径は２ｎｍ程度であり、ＺｒＯ２層の厚さは５ｎｍ程度であった。このＲｈ粒子ＪをＩＣＰ分析したところ、Ｒｈが２．１７ｗｔ％含有されていた。 When the Rh particles J were observed with a TEM, the particle size of the Rh particles was about 2 nm, and the thickness of the ZrO 2 layer was about 5 nm. When this Rh particle J was analyzed by ICP, it contained 2.17 wt% Rh.

[実施例１]
針状ベーマイト２４９．７５ｇ（水分が１５ｗｔ％含有されたもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ａを３０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ａをアルミナで被覆した粉末ａを調製した。粉末ａを１７３．４ｇとベーマイトアルミナ１．６ｇとをボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０％の硝酸水溶液１７．５ｇとを加えて、粉末ａを分散させると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリａ）。 [Example 1]
249.75 g of acicular boehmite (containing 15 wt% of water) was placed in a beaker, dispersed in water and peptized with acid, and 30 g of Pt particles A prepared previously were added and dispersed. This slurry was dried and fired to prepare powder a in which Pt particles A were coated with alumina. 173.4 g of powder a and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill to disperse the powder a and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry a).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24 wt% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% of rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and 10 wt% were further added. A nitric acid aqueous solution (17.5 g) was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６φｍｍ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリａを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌコーティングして乾燥し、その後、４００℃で焼成して実施例１の試料とした。得られた実施例１の試料は、Ｐｔを０．５８７ｇ／Ｌ、Ｒｈを０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity: 0.04L) having a diameter of 36φmm and 400 cells, coated with slurry a at 141 g / L and dried, then coated with slurry R at 59 g / L and dried, and then at 400 ° C. The sample of Example 1 was fired. The obtained sample of Example 1 is a catalyst carrying 0.587 g / L of Pt and 0.236 g / L of Rh.

[実施例２]
針状ベーマイト１４７．３６ｇ（水分が１５ｗｔ％含有されたもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｂを６０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ｂをアルミナで被覆した粉末ｂを調製した。粉末ｂを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて、粉末ｂを分散させると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｂ）。 [Example 2]
147.36 g of acicular boehmite (containing 15 wt% water) was put in a beaker, dispersed in water and peptized with an acid, and 60 g of the previously prepared Pt particles B were added and dispersed. This slurry was dried and fired to prepare powder b in which Pt particles B were coated with alumina. 173.4 g of powder b and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder b and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry b).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化してジルコニア基材を調製した。 Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24 wt% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末を１１６．５５ｇと、ジルコニア基材を４４．４５ｇと、アルミナ基材を１１ｇと、ベーマイトアルミナを３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water was further added. Then, 17.5 g of a 10 wt% nitric acid aqueous solution was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６φｍｍ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリｂを１４１ｇ／Ｌコーティングして乾燥した後、スラリＲを５９ｇ／Ｌコーティングして乾燥し、その後、４００℃で焼成して実施例２の試料とした。得られた実施例２の試料は、Ｐｔ ０．５８７ｇ／Ｌ、Ｒｈ０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity 0.04 L) having a diameter of 36 φmm and a capacity of 400 cells is coated with 141 g / L of slurry b, dried, then coated with 59 g / L of slurry R, dried, and then fired at 400 ° C. The sample of Example 2 was obtained. The obtained sample of Example 2 is a catalyst carrying Pt 0.587 g / L and Rh 0.236 g / L, respectively.

[実施例３]
針状ベーマイト２４９．７５ｇ（水分が１５ｗｔ％含有されたもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｃを３０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ内包セリア粒子をアルミナで被覆した粉末ｃを調製した。粉末ｃを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０％硝酸水溶液１７．５ｇとを加えて、粉末ｃを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｃ）。 [Example 3]
249.75 g of acicular boehmite (containing 15 wt% of water) was placed in a beaker, dispersed in water and peptized with an acid, and 30 g of the previously prepared Pt particles C were added and dispersed. This slurry was dried and fired to prepare a powder c in which Pt-containing ceria particles were coated with alumina. 173.4 g of powder c and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill to disperse the powder c and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry c).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化してジルコニア基材を調製した。 Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24% of cerium oxide with zirconium oxide.

ロジウム０．６ｗｔ％担持粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a rhodium 0.6 wt% supported powder, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and a 10 wt% nitric acid aqueous solution were further added. 17.5 g was added and pulverized to obtain a slurry having an average particle diameter of 3 μm (Slurry R).

直径：３６φｍｍ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｃを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌコーティングして乾燥し、その後、４００℃で焼成して実施例３の試料とした。得られた実施例３の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity: 0.04 L) having a diameter of 36 φmm and 400 cells is coated with slurry c at 141 g / L and dried, and then coated with slurry R at 59 g / L and dried, and then 400 ° C. The sample of Example 3 was baked. The obtained sample of Example 3 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例４]
針状ベーマイト１３２．８０ｇ（水分が１５ｗｔ％含有されたもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｄを７０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ｄをアルミナで被覆した粉末ｄを調製した。粉末ｄを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて、粉末ｄを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｄ）。 [Example 4]
When 132.80 g of acicular boehmite (containing 15 wt% of water) was placed in a beaker, dispersed in water and peptized with an acid, 70 g of the previously prepared Pt particles D were added and dispersed. This slurry was dried and fired to prepare powder d in which Pt particles D were coated with alumina. 173.4 g of powder d and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder d and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry d).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% of rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and 10 wt% were further added. A nitric acid aqueous solution (17.5 g) was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｄを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌにてコーティングして乾燥し、その後、４００℃で焼成して実施例４の試料とした。得られた実施例４の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   The honeycomb carrier (capacity: 0.04 L) having a diameter of 36 mmφ and 400 cells is coated with the slurry d at 141 g / L and dried, and then coated with the slurry R at 59 g / L and dried. The sample of Example 4 was obtained by firing at 0 ° C. The obtained sample of Example 4 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例５]
針状ベーマイト１５０．７５ｇ（水分を１５ｗｔ％含有したもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｅを５０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ｅをアルミナで被覆した粉末ｅを調製した。粉末ｅ１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて、粉末ｅを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｅ）。 [Example 5]
When 150.75 g of acicular boehmite (containing 15 wt% of water) was put in a beaker, dispersed in water and peptized with acid, 50 g of the previously prepared Pt particles E were added and dispersed. This slurry was dried and fired to prepare powder e in which Pt particles E were coated with alumina. 173.4 g of powder e and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder e and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry e).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24 wt% of cerium oxide with zirconium oxide.

ロジウム０．６ｗｔ％担持粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of rhodium 0.6 wt% powder, 44.45 g of zirconia base material, 11 g of alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and a 10 wt% nitric acid aqueous solution were further added. 17.5 g was added and pulverized to obtain a slurry having an average particle diameter of 3 μm (Slurry R).

直径：３６ｍｍφ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｅを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌにてコーティングして乾燥し、その後、４００℃で焼成して実施例５の試料とした。得られた実施例５の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   After coating and drying slurry e at 141 g / L on a honeycomb carrier (capacity: 0.04 L) having a diameter of 36 mmφ, 400 cells and 6 mil, slurry R is coated at 59 g / L and then dried. The sample of Example 5 was fired at 400 ° C. The obtained sample of Example 5 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例６]
針状ベーマイト９７．５２ｇ（水分が１５ｗｔ％含有されているもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｆを１００ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ｆをアルミナで被覆した粉末ｆを調製した。粉末ｆを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％の硝酸水溶液１７．５ｇとを加えて、粉末ｆを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｆ）。 [Example 6]
When 97.52 g of acicular boehmite (containing 15 wt% of water) was placed in a beaker, dispersed in water and peptized with an acid, 100 g of the previously prepared Pt particles F were added and dispersed. This slurry was dried and fired to prepare powder f in which Pt particles F were coated with alumina. 173.4 g of powder f and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder f and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry f).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24 wt% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％の硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% of rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and 10 wt% were further added. 17.5 g of an aqueous nitric acid solution was added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry R).

直径３６φｍｍ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｆを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌコーティングして乾燥し、その後、４００℃で焼成して実施例６の試料とした。得られた実施例６の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity: 0.04 L) having a diameter of 36 φmm and 400 cells is coated and dried with 141 g / L of slurry f, dried with 59 g / L of slurry R, and then dried at 400 ° C. The sample of Example 6 was fired. The obtained sample of Example 6 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例７]
針状ベーマイト１７５．４１ｇ（水分が１５ｗｔ％含有されているもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｇを４０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ｇをアルミナで被覆した粉末ｇを調製した。粉末ｇを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％の硝酸水溶液１７．５ｇとを加えて、粉末ｇを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｇ）。 [Example 7]
175.41 g of acicular boehmite (containing 15 wt% of water) was put in a beaker, dispersed in water and peptized with acid, and then 40 g of the previously prepared Pt particles G were added and dispersed. This slurry was dried and fired to prepare powder g in which Pt particles G were coated with alumina. 173.4 g of powder g and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder g and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry g).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina, 307.5 g of water and 10% A nitric acid aqueous solution (17.5 g) was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｇを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌにてコーティングして乾燥し、その後、４００℃で焼成して実施例７の試料とした。得られた実施例７の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity: 0.04 L) having a diameter of 36 mmφ and 400 cells of 6 mil was coated with a slurry g of 141 g / L and dried, and then coated with a slurry R of 59 g / L and dried. The sample of Example 7 was obtained by firing at 0 ° C. The obtained sample of Example 7 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例８]
針状ベーマイト１０７．９０ｇ（水分を１５ｗｔ％含有したもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ粒子Ｈを９０ｇを加えて分散させた。このスラリーを乾燥、焼成してＰｔ粒子Ｈをアルミナで被覆した粉末ｈを調製した。粉末ｈを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて、粉末ｈを分散すると共に粉末を粉砕し、平均粒径が３μｍのスラリとした（スラリｈ）。 [Example 8]
107.90 g of acicular boehmite (containing 15 wt% of water) was put in a beaker, dispersed in water and peptized with acid, and 90 g of Pt particles H prepared previously were added and dispersed therein. This slurry was dried and fired to prepare powder h in which Pt particles H were coated with alumina. 173.4 g of powder h and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder h and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry h).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24 wt% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径が３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% of rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and 10 wt% were further added. A nitric acid aqueous solution (17.5 g) was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６φｍｍ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｈを１４１ｇ／Ｌコーティングして乾燥した後、スラリＲを５９ｇ／Ｌにてコーティングして乾燥し、その後、４００℃で焼成して実施例８の試料とした。得られた実施例８の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity: 0.04 L) having a diameter of 36 φmm and 400 cells and 6 mil was coated with 141 g / L of slurry h and dried, and then coated with slurry R at 59 g / L and dried, and then at 400 ° C. The sample of Example 8 was fired. The obtained sample of Example 8 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例９]
針状ベーマイト２０６．６６ｇ（水分を１５ｗｔ％含有したもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｄ粒子Ｉを５０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｄ粒子Ｉをアルミナで被覆した粉末ｉを調製した。粉末ｉを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて、粉末ｉを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした（スラリｉ ）。 [Example 9]
When 206.66 g of acicular boehmite (containing 15 wt% of water) was placed in a beaker and dispersed in water and peptized with an acid, 50 g of the previously prepared Pd particles I were added and dispersed. This slurry was dried and fired to prepare powder i in which Pd particles I were coated with alumina. 173.4 g of powder i and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder i and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm (slurry i).

次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化してジルコニア基材を調製した。   Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24% of cerium oxide with zirconium oxide.

ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of a powder carrying 0.6 wt% rhodium, 44.45 g of a zirconia base material, 11 g of an alumina base material, and 3 g of boehmite alumina, 307.5 g of water and 10% A nitric acid aqueous solution (17.5 g) was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６φｍｍ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリｉを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌコーティングして乾燥し、その後、４００℃で焼成して実施例９の試料とした。得られた実施例９の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 After coating the slurry i with 141 g / L on a honeycomb carrier (capacity: 0.04 L) having a diameter of 36 φmm and 400 cells and 6 mil, the slurry R was coated with 59 g / L and dried, and then at 400 ° C. The sample of Example 9 was fired. The obtained sample of Example 9 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[実施例１０]
アルミナ基材（γアルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム９ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）にジニトロジアミン白金水溶液を含浸し、乾燥後、４００℃で焼成してＰｔを０．４４ｗｔ％含有したアルミナ基材を調製した。また、セリア基材（セリアに酸化ジルコニウムを２５％複合化したもの）にジニトロジアミン白金水溶液を含浸し、乾燥後、４００℃で焼成し、０．３７５ｗｔ％をＰｔ含有したセリア基材を調製した。 [Example 10]
An alumina substrate (composite of γ-alumina with cerium oxide 9wt%, zirconium oxide 9wt%, lanthanum oxide 6wt%) is impregnated with dinitrodiamineplatinum aqueous solution, dried and calcined at 400 ° C to give Pt 0.44wt % Alumina substrate was prepared. Further, a ceria base material (compound containing 25% zirconium oxide in ceria) was impregnated with a dinitrodiamine platinum aqueous solution, dried and fired at 400 ° C. to prepare a ceria base material containing 0.375 wt% Pt. .

Ｐｔを０．４４ｗｔ％含有したアルミナ基材１２４．８ｇと、Ｐｔを０．３７５ｗｔ％含有したセリア基材４８．６ｇと、ベーマイトアルミナ１．６ｇと、をボールミルに加え、さらに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉末を粉砕し、平均粒径３μｍのスラリとした。（スラリＸ）
針状ベーマイト１５３．８９ｇ（水分を１５ｗｔ％含有したもの）をビーカーに入れ、水に分散させて酸で解膠したところに前に調製したＲｈ粒子Ｊを５０ｇ加えて分散させた。このスラリーを乾燥、焼成して、Ｒｈ粒子Ｊをアルミナで被覆した粉末ｊを調製した。粉末ｊを１１６．５５ｇと、実施例１で調製したジルコニア基材４４．４５ｇ、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇとを、ボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒子径３μｍのスラリーとした。（スラリーＳ）
直径３６φｍｍ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリＸを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＳを５９ｇ／Ｌにてコーティングして乾燥し、その後、４００℃で焼成して実施例１０の試料とした。得られた実施例１０の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 124.8 g of an alumina base material containing 0.44 wt% of Pt, 48.6 g of a ceria base material containing 0.375 wt% of Pt, and 1.6 g of boehmite alumina are added to a ball mill, and further 307.5 g of water. And 17.5 g of a 10 wt% nitric acid aqueous solution were added, and the powder was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry X)
153.89 g of acicular boehmite (containing 15 wt% of water) was placed in a beaker, dispersed in water and peptized with an acid, and 50 g of the previously prepared Rh particles J were added and dispersed. This slurry was dried and fired to prepare powder j in which Rh particles J were coated with alumina. 116.55 g of powder j, 44.45 g of the zirconia base material prepared in Example 1, 11 g of the alumina base material, and 3 g of boehmite alumina were added to a ball mill, and then 307.5 g of water and 10 wt% nitric acid were added. 17.5 g of an aqueous solution was added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry S)
A honeycomb carrier (capacity: 0.04L) having a diameter of 36φmm and 400 cells and 6 mils was coated with slurry X at 141 g / L and dried, and then coated with slurry S at 59 g / L and dried, and then 400 The sample of Example 10 was fired at 0 ° C. The obtained sample of Example 10 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[比較例１]
アルミナ基材（γアルミナに酸化セリウムを９ｗｔ％、酸化ジルコニウムを９ｗｔ％、酸化ランタンを６ｗｔ％複合化したもの）にジニトロジアミン白金水溶液を含浸し、乾燥後、４００℃で焼成してＰｔを０．４４ｗｔ％含有したアルミナ基材を調製した。また、セリア基材（セリアに酸化ジルコニウムを２５ｗｔ％複合化したもの）にジニトロジアミン白金水溶液を含浸し、乾燥後、４００℃で焼成し、０．３７５ｗｔ％をＰｔ含有したセリア基材を調製した。 [Comparative Example 1]
An alumina base material (composite of 9 wt% cerium oxide, 9 wt% zirconium oxide and 6 wt% lanthanum oxide in γ-alumina) is impregnated with an aqueous solution of dinitrodiamine platinum, dried, fired at 400 ° C., and Pt is 0 An alumina substrate containing .44 wt% was prepared. Also, a ceria substrate (composite of ceria with 25 wt% zirconium oxide) was impregnated with a dinitrodiamine platinum aqueous solution, dried, and then fired at 400 ° C. to prepare a ceria substrate containing 0.375 wt% Pt. .

Ｐｔを０．４４ｗｔ％含有したアルミナ基材１２４．８ｇと、Ｐｔを０．３７５ｗｔ％含有したセリア基材４８．６ｇと、ベーマイトアルミナ１．６ｇと、をボールミルに加え、さらに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉末を粉砕し、平均粒径３μｍのスラリとした。（スラリＸ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリＸを１４１ｇ／Ｌにてコーティングし、乾燥後、さらに実施例１で調製したスラリＲを５９ｇ／Ｌにてコーティングし、乾燥後、４００℃で焼成して比較例１の試料とした。比較例１の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを担持した触媒であり、いわゆる通常の貴金属を含浸した触媒である。 124.8 g of an alumina base material containing 0.44 wt% of Pt, 48.6 g of a ceria base material containing 0.375 wt% of Pt, and 1.6 g of boehmite alumina are added to a ball mill, and further 307.5 g of water. And 17.5 g of a 10 wt% nitric acid aqueous solution were added, and the powder was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry X)
A honeycomb carrier (capacity: 0.04 L) having a diameter of 36 mmφ and 400 cells is coated with slurry X at 141 g / L, dried, and further coated with slurry R prepared in Example 1 at 59 g / L. After drying, the sample of Comparative Example 1 was obtained by firing at 400 ° C. The sample of Comparative Example 1 is a catalyst supporting Pt: 0.587 g / L and Rh: 0.236 g / L, and is a catalyst impregnated with a so-called normal noble metal.

[比較例２]
平均粒子径が４０ｎｍのＣｅＯ２にジニトロジアミンＰｔを含浸して、乾燥、焼成し、Ｐｔ含有量が０．８４２ｗｔ％のＰｔ担持ＣｅＯ２粒子Ｋを調製した。 [Comparative Example 2]
CeO 2 having an average particle size of 40 nm was impregnated with dinitrodiamine Pt, dried and fired to prepare Pt-supported CeO 2 particles K having a Pt content of 0.842 wt%.

針状ベーマイト１０５．８８ｇ（水分が１５ｗｔ％含有されているもの）をビーカーに入れ、水に分散させ酸で解膠したところに、前に調製したＰｔ担持ＣｅＯ２粒子Ｋを９０ｇ加えて分散させた。このスラリーを乾燥、焼成してＰｔ担持セリア粒子Ｋをアルミナで被覆した粉末ｋを調製した。粉末ｋを１７３．４ｇとベーマイトアルミナ１．６ｇと、をボールミルに加えた。その後、ボールミルに、水３０７．５ｇと１０ｗｔ％硝酸水溶液１７．５ｇとを加えて、粉末ｊを分散すると共に粉末を粉砕し、平均粒径３μｍのスラリとした。（スラリｋ）
次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと、酸化ジルコニウム複合化合物に硝酸ロジウムを含浸し、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化してジルコニア基材を調製した。 In a beaker, 105.88 g of acicular boehmite (containing 15 wt% water) was dispersed in water and peptized with acid, and 90 g of Pt-supported CeO2 particles K prepared earlier were added and dispersed. . This slurry was dried and fired to prepare powder k in which Pt-supported ceria particles K were coated with alumina. 173.4 g of powder k and 1.6 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added to the ball mill to disperse the powder j and pulverize the powder to obtain a slurry having an average particle diameter of 3 μm. (Slurry k)
Next, γ-alumina containing 3 wt% as zirconium and a zirconium oxide composite compound were impregnated with rhodium nitrate to prepare a 0.6 wt% rhodium supported powder. A zirconia base material was prepared by compounding 24 wt% of cerium oxide with zirconium oxide.

ロジウム０．６ｗｔ％を担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇと、アルミナ基材１１ｇと、ベーマイトアルミナ３ｇと、をボールミルに加えた後、さらに、水３０７．５ｇと、１０ｗｔ％硝酸水溶液１７．５ｇとを加えて粉砕し、平均粒径３μｍのスラリとした（スラリＲ）。   After adding 116.55 g of powder carrying 0.6 wt% rhodium, 44.45 g of zirconia base material, 11 g of alumina base material, and 3 g of boehmite alumina to a ball mill, 307.5 g of water and 10 wt% were further added. A nitric acid aqueous solution (17.5 g) was added and pulverized to form a slurry having an average particle diameter of 3 μm (slurry R).

直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量：０．０４Ｌ）にスラリーｋを１４１ｇ／Ｌにてコーティングして乾燥した後、スラリＲを５９ｇ／Ｌコーティングして乾燥し、その後、４００℃で焼成して比較例２の試料とした。得られた比較例２の試料は、Ｐｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。   A honeycomb carrier (capacity: 0.04 L) having a diameter of 36 mmφ and 400 cells and 6 mils was coated with slurry k at 141 g / L and dried, then slurry R was coated with 59 g / L and dried, and then at 400 ° C. The sample of Comparative Example 2 was fired. The obtained sample of Comparative Example 2 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.

[評価]
前記実施例１〜実施例１０及び比較例１〜比較例２により調製した触媒を用いて、排気量３５００ｃｃのＶ型エンジンの排気系に、片バンクあたり触媒を各５個ずつ装着した。国内レギュラーガソリンを使用して、触媒入口温度を６５０℃とし、３０時間運転して耐久試験により熱履歴を施した。 [Evaluation]
Using the catalysts prepared in Examples 1 to 10 and Comparative Examples 1 to 2, five catalysts per bank were installed in the exhaust system of a V-type engine with a displacement of 3500 cc. Domestic regular gasoline was used, the catalyst inlet temperature was set to 650 ° C., operation was performed for 30 hours, and a heat history was given by an endurance test.

さらに、耐久試験後の各触媒を模擬排ガス流通装置に組み込み、下記の表２に示す組成の模擬排ガスを模擬排ガス流通装置に流通させて、触媒温度を３０℃／分の速度で昇温させながら、ＮＯｘ、ＣＯ、ＨＣ（Ｃ３Ｈ６）の浄化率が５０％となる温度（Ｔ５０）を調べた。前述した表１に、実施例１〜実施例１０及び比較例１〜比較例２の各触媒の評価結果を示すと共に、図４に、ＨＣ（Ｃ３Ｈ６）浄化率が５０％となる温度の関係を示した。

Figure 2007253037
Further, each catalyst after the endurance test is incorporated into the simulated exhaust gas distribution device, and the simulated exhaust gas having the composition shown in Table 2 below is distributed to the simulated exhaust gas distribution device while raising the catalyst temperature at a rate of 30 ° C./min. The temperature (T50) at which the purification rate of NOx, CO, and HC (C 3 H 6 ) was 50% was examined. Table 1 described above shows the evaluation results of the catalysts of Examples 1 to 10 and Comparative Examples 1 to 2, and FIG. 4 shows the temperature at which the HC (C 3 H 6 ) purification rate becomes 50%. Showed the relationship.
Figure 2007253037

評価結果から、比較例１は、貴金属溶液を使用し通常使用される含浸法を用いてを調製した触媒であるため、初期のＰｔ粒径は非常に小さく分散性が良かったが、耐久後のＰｔ粒子をＴＥＭで観察したところ、Ｐｔ粒径が約２０ｎｍ〜３０ｎｍとなりＰｔ粒子が凝集していた。   From the evaluation results, Comparative Example 1 is a catalyst prepared by using a commonly used impregnation method using a noble metal solution, so that the initial Pt particle size was very small and the dispersibility was good. When the Pt particles were observed with a TEM, the Pt particle size was about 20 nm to 30 nm, and the Pt particles were aggregated.

比較例２の触媒は、ＣｅＯ２粒子にＰｔを含浸担持したものであり、初期のＰｔ粒径は非常に小さく分散性が良かった。又、耐久後の触媒について、Ｐｔ粒子をＴＥＭで観察したところ、Ｐｔ粒径が約７ｎｍ〜１０ｎｍと小さかったが、Ｐｔ粒子の凝集が確認された。これは、ＣｅＯ２にＰｔを担持しているため、ＣｅＯ２のアンカー効果により、Ptの凝集は抑制されるがＰｔ粒子の凝集は生じてしまうことによるものと考えられる。 The catalyst of Comparative Example 2 was obtained by impregnating and supporting Pt on CeO 2 particles, and the initial Pt particle size was very small and the dispersibility was good. Moreover, when the Pt particles were observed with a TEM for the catalyst after endurance, the Pt particle diameter was as small as about 7 nm to 10 nm, but aggregation of the Pt particles was confirmed. This is because it carries a Pt to CeO 2, by the anchor effect of CeO 2, aggregation of Pt is being suppressed is thought to be due to occur agglomeration of the Pt particles.

これに対して、実施例１〜実施例１０の各触媒では、耐久試験前及び耐久試験後のＰｔ粒子径に大きな変化はなく、各実施例の触媒が熱履歴に対して耐久性に優れているこことが判明した。特に、実施例２、実施例３、実施例４、実施例９の各触媒は、いずれもＮＯｘ、ＣＯ、ＨＣの浄化率が５０％となる温度が低く、触媒活性が高いことが判明した。   On the other hand, in each catalyst of Examples 1 to 10, there was no significant change in the Pt particle diameter before and after the durability test, and the catalyst of each example was excellent in durability against heat history. It turned out to be. In particular, it was found that each of the catalysts of Examples 2, 3, 4, and 9 has a low temperature at which the NOx, CO, and HC purification rates are 50%, and has a high catalytic activity.

本発明の実施形態による排気ガス浄化用触媒を拡大して示す概略図である。It is the schematic which expands and shows the catalyst for exhaust gas purification by embodiment of this invention. 本発明の実施形態による真空蒸着装置の概略を示す断面図である。It is sectional drawing which shows the outline of the vacuum evaporation system by embodiment of this invention. 本図は、本発明の実施形態による排気ガス浄化用触媒の製造工程を示す概略図であり、（ａ）は貴金属粒子を示し、（ｂ）は貴金属粒子を第１の被覆層で覆った状態を示し、（ｃ）は第１の被覆層を第２の被覆層で覆った状態を示している。FIG. 1 is a schematic view showing a manufacturing process of an exhaust gas purifying catalyst according to an embodiment of the present invention, wherein (a) shows noble metal particles, and (b) shows a state in which the noble metal particles are covered with a first coating layer. (C) has shown the state which covered the 1st coating layer with the 2nd coating layer. 実施例１〜１０及び比較例１〜２における各触媒のＨＣ（Ｃ３Ｈ６）浄化率が５０％となる温度を比較したグラフである。Examples 1 to 10 and HC of each catalyst in Comparative Example 1~2 (C 3 H 6) purification ratio is a graph comparing the temperature at which 50%.

符号の説明Explanation of symbols

１…排気ガス浄化用触媒
３…貴金属粒子
５…第１の被覆層
７…第２の被覆層

DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification catalyst 3 ... Noble metal particle 5 ... 1st coating layer 7 ... 2nd coating layer

Claims (6)

貴金属粒子と、該貴金属粒子を覆う第１の被覆層と、この第１の被覆層を覆う第２の被覆層とを備えてなる排気ガス浄化用触媒であって、
前記第１の被覆層は、Ａｌ，Ｃｅ，Ｚｒ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉの単体又はこれらの酸化物から選択される群のうち、少なくともいずれかからなり、
前記第２の被覆層は、アルミナ及びジルコニアの少なくともいずれかからなることを特徴とする排気ガス浄化用触媒。 An exhaust gas purifying catalyst comprising noble metal particles, a first coating layer covering the noble metal particles, and a second coating layer covering the first coating layer,
The first coating layer is composed of at least one selected from the group consisting of a single substance of Al, Ce, Zr, Mn, Co, Fe, and Ni, or an oxide thereof.
The exhaust gas purifying catalyst, wherein the second coating layer is made of at least one of alumina and zirconia. 前記貴金属粒子は、白金、パラジウム及びロジウムから選択される少なくともいずれかからなることを特徴とする請求項１に記載の排気ガス浄化用触媒。   The exhaust gas purifying catalyst according to claim 1, wherein the noble metal particles are made of at least one selected from platinum, palladium, and rhodium. 前記第１の被覆層は、クラスターの集合体から形成されることを特徴とする請求項１又は２に記載の排気ガス浄化用触媒。   The exhaust gas purifying catalyst according to claim 1 or 2, wherein the first coating layer is formed of an aggregate of clusters. 前記貴金属粒子の粒子径は、１〜５ｎｍであることを特徴とする請求項１〜３のいずれか１項に記載の排気ガス浄化用触媒。   The exhaust gas purifying catalyst according to any one of claims 1 to 3, wherein a particle diameter of the noble metal particles is 1 to 5 nm. 前記第１の被覆層における平均の厚さは、２０ｎｍ以下であることを特徴とする請求項１〜４のいずれか１項に記載の排気ガス浄化用触媒。   The exhaust gas purifying catalyst according to any one of claims 1 to 4, wherein an average thickness of the first coating layer is 20 nm or less. ガス中蒸発法を用いて、貴金属粒子を第１の被覆層で覆う工程と、
該第１の被覆層を第２の被覆層で覆う工程とを含み、
前記第１の被覆層は、Ａｌ，Ｃｅ，Ｚｒ，Ｍｎ，Ｃｏ，Ｆｅ，Ｎｉ又はこれらの酸化物から選択される少なくともいずれかからなり、
前記第２の被覆層は、アルミナ及びジルコニアの少なくともいずれかからなることを特徴とする排気ガス浄化用触媒の製造方法。

Covering the noble metal particles with a first coating layer using a gas evaporation method;
Covering the first coating layer with a second coating layer,
The first coating layer is composed of at least one selected from Al, Ce, Zr, Mn, Co, Fe, Ni, or an oxide thereof.
The method for producing an exhaust gas purifying catalyst, wherein the second coating layer is made of at least one of alumina and zirconia.

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