JP5028857B2 - Exhaust gas purification catalyst and method for producing the same - Google Patents
Exhaust gas purification catalyst and method for producing the same Download PDFInfo
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Description
本発明は、内燃機関から排出される排気ガスの浄化処理に適用される排ガス浄化触媒及びその製造方法に関する。 The present invention relates to an exhaust gas purification catalyst applied to a purification process of exhaust gas discharged from an internal combustion engine and a method for manufacturing the same.
内燃機関から排出される排気ガス中に含まれる炭化水素系化合物（ＨＣ）、一酸化炭素（ＣＯ）、窒素酸化物（ＮＯｘ）等の有害物質を除去するために、アルミナ（Ａｌ２Ｏ３）等の金属酸化物担体に白金（Ｐｔ）やパラジウム（Ｐｄ）やロジウム（Ｒｈ）等の触媒活性を有する貴金属粒子を担持した排ガス浄化触媒が広く利用されている。 In order to remove harmful substances such as hydrocarbon compounds (HC), carbon monoxide (CO), and nitrogen oxides (NO x ) contained in the exhaust gas discharged from the internal combustion engine, alumina (Al 2 O 3) Exhaust gas purification catalysts in which noble metal particles having catalytic activity such as platinum (Pt), palladium (Pd), and rhodium (Rh) are supported on a metal oxide carrier such as) are widely used.
近年の排気ガス規制はますます厳しくなる一方であり、この規制をクリアするためには、多くの貴金属を使用する必要がある。しかし、貴金属の大量使用は地球資源の枯渇の観点から望ましくない。従来の排ガス浄化触媒において貴金属量が増える原因の一つは、耐久性確保のためである。よって耐久性を確保できれば、貴金属量を著しく減らすことが可能となる。また、排ガス浄化触媒は、内燃機関から排出される高温の排ガスと接触するので、高温、長時間の使用によっても触媒性能の低下が少ない、耐久性に優れることが求められる。 The exhaust gas regulations in recent years are becoming stricter, and in order to satisfy these regulations, it is necessary to use many precious metals. However, mass use of precious metals is not desirable from the viewpoint of depletion of earth resources. One of the causes of the increase in the amount of noble metal in the conventional exhaust gas purification catalyst is to ensure durability. Therefore, if durability can be secured, the amount of noble metal can be significantly reduced. Further, since the exhaust gas purifying catalyst comes into contact with the high temperature exhaust gas discharged from the internal combustion engine, it is required to have excellent durability with little deterioration in the catalyst performance even when used at a high temperature for a long time.
排ガス浄化触媒の耐久性向上のためには、貴金属及びこの貴金属を担持する酸化物担体等の配置を適正にすることが重要だと考えられる。しかしながら、これらの配置の設計は難しく、例えば、含浸法で貴金属を担体に担持させる場合、溶液のｐＨや塩を変える等の調整により、貴金属と担体とを互いに接触させていたが、触媒設計から見て完全なものではなかった。また、貴金属粒子径は、貴金属の耐久性向上を考慮すると２ｎｍ以上で、触媒活性を考慮すると５ｎｍ以下であることが理想であるが、従来の含浸法では貴金属粒子径が１ｎｍ以下となり、理想である上記粒子径の範囲に調整することが困難であった。 In order to improve the durability of the exhaust gas purifying catalyst, it is considered important to properly arrange the noble metal and the oxide carrier supporting the noble metal. However, it is difficult to design these arrangements. For example, when a noble metal is supported on a support by an impregnation method, the noble metal and the support are brought into contact with each other by adjusting the pH or salt of the solution. It wasn't perfect to see. In addition, the noble metal particle diameter is ideally 2 nm or more when considering the durability improvement of the noble metal and 5 nm or less when considering the catalytic activity, but the noble metal particle diameter is ideally 1 nm or less in the conventional impregnation method. It was difficult to adjust to a certain particle size range.
また、貴金属を含有するペロブスカイト型複合酸化物が、θ−アルミナ及び／又はα−アルミナに担持されている配置になる排ガス浄化触媒が提案されている（特許文献１）。
しかしながら、貴金属を含有するペロブスカイト型複合酸化物が、θ−アルミナ及び／又はα−アルミナに担持されている配置になる排ガス浄化触媒では、例えばアルコキシド法により製造する場合の製造過程で、当該ペロブスカイト型複合酸化物を構成する各種元素のゲル化速度が異なるため、均一な貴金属含有ペロブスカイト型複合酸化物が形成されない。その結果、ペロブスカイト構造に含有されなかった貴金属（例えばＰｄ）は安定して担持されず、排ガス浄化触媒の使用環境における高温により次第に凝集し、劣化してしまう。 However, in the exhaust gas purification catalyst in which the perovskite type composite oxide containing a noble metal is supported by θ-alumina and / or α-alumina, the perovskite type oxide is used in the manufacturing process in the case of manufacturing by an alkoxide method, for example. Since the gelation rates of various elements constituting the complex oxide are different, a uniform noble metal-containing perovskite complex oxide is not formed. As a result, the noble metal (for example, Pd) not contained in the perovskite structure is not stably supported, and gradually aggregates and deteriorates due to the high temperature in the environment where the exhaust gas purification catalyst is used.
本発明の排ガス浄化触媒は、貴金属及び希土類元素を含有する複合酸化物と、耐熱性酸化物とを有し、前記複合酸化物が、前記貴金属としてのＰｄと前記希土類元素としてのランタノイドＬｎとの複合酸化物であるＬｎ ４ ＰｄＯ ７ を含み、前記Ｌｎ ４ ＰｄＯ ７ を含む複合酸化物の周囲に前記耐熱性酸化物が配置され、前記複合酸化物Ｌｎ ４ ＰｄＯ ７ の粒子径が１ｎｍ〜５００ｎｍであり、前記複合酸化物同士が、この耐熱性酸化物により隔てられた構造のユニットを含むことを要旨とする。 Exhaust gas purifying catalyst of the present invention, a composite oxide containing a noble metal and rare earth elements, and a refractory oxide, the composite oxide, the lanthanide Ln as the rare earth element and Pd as the noble metal include Ln 4 PdO 7 is a composite oxide, the heat-resistant oxide around the composite oxide containing the Ln 4 PdO 7 is arranged, the particle diameter of the composite oxide Ln 4 PdO 7 is in 1nm~500nm The gist is that the composite oxides include units having a structure separated by the heat-resistant oxide.
また、本発明の排ガス浄化触媒の製造方法は、貴金属原料溶液と希土類元素原料溶液とを混合し、貴金属と希土類元素とを含む複合酸化物前駆体を沈殿させた後、この複合酸化物前駆体をろ過、乾燥、焼成して複合酸化物粉を形成し、次いでこの複合酸化物粉と耐熱性酸化物原料溶液とを混合して当該複合酸化物粉の粒子の周りに耐熱性酸化物前駆体を形成させて沈殿させた後、ろ過、乾燥、焼成する工程を有することを要旨とする。 The production how the exhaust gas purifying catalyst of the present invention, by mixing the noble metal raw material solution and the rare earth element raw material solution, after precipitation of the composite oxide precursor containing a noble metal and a rare earth element, the composite oxide precursor The body is filtered, dried, and fired to form a composite oxide powder, and then the composite oxide powder and the heat-resistant oxide raw material solution are mixed to form a heat-resistant oxide precursor around the composite oxide powder particles. The gist is to have a step of filtering, drying and firing after the body is formed and precipitated.
本発明の排ガス浄化触媒によれば、貴金属が複合酸化物に担持され、この貴金属を担持した複合酸化物を耐熱性酸化物で隔てる構造により、触媒活性が向上し、耐久性が向上した排ガス浄化触媒が得られる。 According to the exhaust gas purifying catalyst of the present invention, a structure in which a noble metal is supported on a composite oxide and the composite oxide supporting the noble metal is separated by a heat-resistant oxide, the catalytic activity is improved and the exhaust gas purification is improved in durability. A catalyst is obtained.
以下、本発明の排ガス浄化触媒の実施形態について、図面を用いつつ説明する。 Hereinafter, embodiments of the exhaust gas purifying catalyst of the present invention will be described with reference to the drawings.
図１は、本発明の一実施形態となる排ガス浄化触媒の模式図である。同図に示す排ガス浄化触媒は、複合酸化物１と、この複合酸化物の周囲に形成された耐熱性酸化物２とを有している。この複合酸化物１は、貴金属と希土類元素とを含有する複合酸化物であり、このことにより、貴金属が複合酸化物に担持されていることになる。また、この複合酸化物１同士が、耐熱性酸化物２により隔てられた構造のユニットを形成している。図１では、耐熱性酸化物２により隔てられたユニット内には、複合酸化物１が単数の個数で含まれている例を示しているが、この耐熱性酸化物２により隔てられたユニット内には、所定の粒子径になる複数個の複合酸化物を含有することができる。
FIG. 1 is a schematic diagram of an exhaust gas purification catalyst according to an embodiment of the present invention. The exhaust gas purification catalyst shown in the figure has a composite oxide 1 and a heat-
図１に示した本実施形態に係る排ガス浄化触媒について、より具体的に述べると、複合酸化物１は、貴金属元素としてのＰｄと、希土類元素としてのランタノイド（以下、ランタノイドを「Ｌｎ」ともいう。）との複合酸化物であるＬｎ４ＰｄＯ７を少なくとも含むものであり、このＬｎ４ＰｄＯ７を含む複合酸化物１の周囲に耐熱性酸化物２が配されている。
More specifically, the exhaust gas purification catalyst according to the present embodiment shown in FIG. 1 will be described. The composite oxide 1 includes Pd as a noble metal element and a lanthanoid as a rare earth element (hereinafter, the lanthanoid is also referred to as “Ln”). . the Ln 4 PdO 7 is a composite oxide of) those containing at least a heat-
図示した本実施形態に係る排ガス浄化触媒の作用効果を以下説明する。排ガスを浄化する触媒活性を有する貴金属のうち、Ｐｄは、低温から炭化水素系化合物（ＨＣ）の酸化に優れており、排ガス浄化触媒として好適である。しかし、Ｐｄは耐熱性が低く、８００℃以上の高温では、触媒中でＰｄが凝集して触媒活性が低下する場合がある。このＰｄの凝集は、排ガスが還元性雰囲気のときに起こり易いが、８７０℃以上の高温では、雰囲気が酸化性、還元性によらず起こり易くなる。発明者らの研究により、８７０以上の高温では、Ｐｄが酸化物の態様よりも金属の態様のほうが安定であり、ＰｄＯの分解によりＰｄがメタル化し、急速に凝縮することによって、触媒活性点の表面積が低下し、触媒活性の低下を招いていたことが明らかとなった。そして、従来の触媒では、ペロブスカイト型の複合酸化物の構造であっても、高温時にはＰｄＯの分解によりＰｄがメタル化して凝集するため、触媒活性が劣化していた。 The effects of the exhaust gas purifying catalyst according to the present embodiment shown in the drawings will be described below. Of the noble metals having catalytic activity for purifying exhaust gas, Pd is excellent in oxidizing hydrocarbon compounds (HC) from a low temperature and is suitable as an exhaust gas purification catalyst. However, Pd has low heat resistance, and at a high temperature of 800 ° C. or higher, Pd may aggregate in the catalyst and the catalytic activity may decrease. This Pd aggregation is likely to occur when the exhaust gas is in a reducing atmosphere, but at a high temperature of 870 ° C. or higher, the atmosphere tends to occur regardless of the oxidizing and reducing properties. According to the research of the inventors, at a high temperature of 870 or more, the metal aspect of Pd is more stable than that of the oxide, and Pd is metalized by the decomposition of PdO and rapidly condensed. It was clarified that the surface area was reduced and the catalytic activity was reduced. In the case of a conventional catalyst, even if it has a structure of a perovskite complex oxide, the catalytic activity deteriorates because Pd is metallized and aggregates due to decomposition of PdO at a high temperature.
本発明に係る排ガス浄化触媒は、前述のように貴金属と、希土類元素を含有する複合酸化物１と、耐熱性酸化物２とからなり、貴金属が、複合酸化物１に担持され、かつ、貴金属が担持された複合酸化物１同士が、耐熱性酸化物２により隔てられた構造のユニットを含むものである。このような構成により、貴金属の酸化物と希土類元素の酸化物との複合酸化物１が、耐熱性を有することから、貴金属の酸化物の分解が抑制される。これにより、排ガス浄化触媒の耐熱性が向上する。また、この複合酸化物１を覆うように耐熱性酸化物２が形成されることにより、複合酸化物１同士が耐熱性酸化物２により隔てられてユニットを形成し、このユニットを抜けて複合酸化物１が凝集すること抑制することができる。したがって、排ガス浄化触媒の耐熱性がより向上する。これらのことから、高温、長時間の使用によっても触媒活性の低下が少ない、優れた排ガス浄化触媒となる。
The exhaust gas purifying catalyst according to the present invention comprises a noble metal, a complex oxide 1 containing a rare earth element, and a heat-
より具体的には、本発明に係る排ガス浄化触媒は、複合酸化物１が、貴金属元素のうちのＰｄと希土類元素のランタノイドＬｎとの複合酸化物であるＬｎ４ＰｄＯ７を少なくとも含むものとする。ＰｄＯとＬｎＯ２との複合酸化物であって、特にＬｎ４ＰｄＯ７を含むような組成範囲になるＰｄＯとＬｎＯ２との複合酸化物１が、１０００℃以上の耐熱性を有し、好適な触媒活性種となる。このようなＬｎ４ＰｄＯ７を含むような組成範囲になるＰｄＯとＬｎＯ２との複合酸化物１のみの構成では、１０００℃以上の高温環境のもとで複合酸化物の粒子同士が接触、凝集し、粒子径が大きくなり活性表面積が低下する結果、所期した触媒活性が得られなくなるおそれがある。そこで、この複合酸化物の周囲に、この複合酸化物とは異なる種類の耐熱性酸化物２を配すことで、この複合酸化物１同士が接触、凝集することを抑制し、１０００℃以上の高温で優れた触媒活性を有する排ガス浄化触媒となる。
More specifically, in the exhaust gas purifying catalyst according to the present invention, the composite oxide 1 includes at least Ln 4 PdO 7 which is a composite oxide of Pd of a noble metal element and a lanthanoid Ln of a rare earth element. A composite oxide of PdO and LnO 2 , particularly a composite oxide 1 of PdO and LnO 2 in a composition range including Ln 4 PdO 7 has a heat resistance of 1000 ° C. or more , and is suitable. It becomes a catalytically active species. In the configuration of only the composite oxide 1 of PdO and LnO 2 having a composition range including Ln 4 PdO 7 , the composite oxide particles are brought into contact and aggregated under a high temperature environment of 1000 ° C. or higher. However, as a result of the particle size being increased and the active surface area being reduced, the desired catalytic activity may not be obtained. Therefore, by arranging a heat-
このランタノイドＬｎは、Ｎｄ、Ｓｍ、Ｇｄ及びＬａのうちの少なくとも一種の希土類元素であることをが好ましい。ランタノイドのなかでも、Ｎｄ、Ｓｍ、Ｇｄ及びＬａの少なくとも一種の元素の酸化物は、ＰｄＯとの複合酸化物としたときに１０００℃以上の高温に耐えることが可能な触媒活性種となり得るからである。これらのランタノイドは、Ｎｄ、Ｓｍ、Ｇｄ及びＬａから選ばれる１種類の元素の酸化物であってもよいし、これらの元素の２種類以上の酸化物であってもよい。 This lanthanoid Ln is preferably at least one rare earth element of Nd, Sm, Gd and La. Among lanthanoids, the oxide of at least one element of Nd, Sm, Gd and La can be a catalytically active species capable of withstanding high temperatures of 1000 ° C. or higher when it is a composite oxide with PdO. is there. These lanthanoids may be oxides of one element selected from Nd, Sm, Gd and La, or may be oxides of two or more of these elements.
また、Ｌｎ４ＰｄＯ７の複合酸化物１は、粒子径が１ｎｍ〜５００ｎｍであることが好ましい。粒子径が１ｎｍに満たないと、複合酸化物１が耐熱性酸化物で囲まれて形成されたユニットから抜け出るおそれがある。また、粒子径が５００ｎｍを超えると、活性表面積が低下する結果、所期した触媒活性が得られなくなるおそれがある。 Further, the composite oxide 1 of Ln 4 PdO 7 preferably has a particle diameter of 1 nm to 500 nm. If the particle diameter is less than 1 nm, the composite oxide 1 may escape from the unit formed by being surrounded by the heat-resistant oxide. On the other hand, if the particle diameter exceeds 500 nm, the active surface area decreases, and the desired catalytic activity may not be obtained.
このＬｎ４ＰｄＯ７の複合酸化物１の粒子径の、より好ましい範囲は、１ｎｍ〜５０ｎｍである。１ｎｍ〜５０ｎｍの範囲で特に優れた触媒活性と耐熱性を得ることができる。 A more preferable range of the particle diameter of the composite oxide 1 of Ln 4 PdO 7 is 1 nm to 50 nm. Particularly excellent catalytic activity and heat resistance can be obtained in the range of 1 nm to 50 nm.
複合酸化物の周囲に配される耐熱性酸化物２は、Ａｌ２Ｏ３、ＺｒＯ２、ＳｉＯ２、ＴｉＯ２及びＣｅＯ２の少なくとも１種の酸化物を含むことが好ましい。これらの酸化物は、一般に触媒担体として使用されている酸化物であり、高温のもとでも安定で、耐熱性が高い酸化物であるため、本発明においても耐熱性酸化物２として用いて好適である。耐熱性酸化物２の形状は、図１に示した線状のものに限られず、例えば粒状のものや、薄片状のものであってもよい。
The heat-
次に、本発明の排ガス浄化触媒の製造方法について説明する。本発明に係る排ガス浄化触媒を製造する際は、貴金属原料溶液と希土類元素原料溶液とを混合し、貴金属と希土類元素とを含む複合酸化物前駆体を沈殿させた後、この複合酸化物前駆体をろ過、乾燥、焼成して複合酸化物粉を形成し、次いでこの複合酸化物粉と耐熱性酸化物原料溶液とを混合して当該複合酸化物粉の粒子の周りに耐熱性酸化物前駆体を形成させて沈殿させた後、ろ過、乾燥、焼成する工程を有することができる。 Next, the manufacturing method of the exhaust gas purification catalyst of the present invention will be described. When producing an exhaust gas purifying catalyst according to the present invention, a noble metal raw material solution and a rare earth element raw material solution are mixed and a composite oxide precursor containing a noble metal and a rare earth element is precipitated. The composite oxide powder is then formed by filtering, drying, and firing, and then the composite oxide powder and the heat-resistant oxide raw material solution are mixed to form a heat-resistant oxide precursor around the composite oxide powder particles. After forming and precipitating, it can have the process of filtering, drying, and baking.
複合酸化物前駆体は、例えばＰｄＯとＬｎ２Ｏ３との複合酸化物前駆体である。この複合酸化物前駆体を得るために、Ｐｄ成分を含む原料溶液とＬｎ成分を含む原料溶液とを混合した後、アルカリにより共沈させる。この酸化物前駆体をろ過、乾燥、焼成して複合酸化物粉を得る。複合酸化物の粒子径は、小さいほどよく、そのため、低い温度で焼成することが望ましい。また、複合酸化物の粒径が小であるときは、次工程にて複合酸化物の周りに配する耐熱性酸化物の前駆体が、この複合酸化物粒間に入りやすく、その結果として熱耐久性も良好になる。焼成後の粉末を、必要に応じて粉砕することもできる。 The composite oxide precursor is, for example, a composite oxide precursor of PdO and Ln 2 O 3 . In order to obtain this composite oxide precursor, a raw material solution containing a Pd component and a raw material solution containing an Ln component are mixed and then coprecipitated with an alkali. This oxide precursor is filtered, dried and fired to obtain a composite oxide powder. The particle diameter of the composite oxide is preferably as small as possible. Therefore, it is desirable to fire at a low temperature. In addition, when the particle size of the composite oxide is small, the precursor of the heat-resistant oxide disposed around the composite oxide in the next step tends to enter between the composite oxide particles, and as a result, Durability is also good. The powder after firing can be pulverized as necessary.
この複合酸化物粉を、耐熱性酸化物の原料溶液中に入れ、分散させた状態で原料溶液から耐熱性酸化物の前駆体を生じさせることにより、複合酸化物の粒子の周囲に耐熱性酸化物の前駆体を形成させることができる。この後は、溶液をろ過して得られた固形物を乾燥、焼成して本発明に係る排ガス浄化触媒粉末を得ることができる。 The composite oxide powder is placed in a heat-resistant oxide raw material solution, and a heat-resistant oxide precursor is generated from the raw material solution in a dispersed state. The precursor of the product can be formed. Thereafter, the solid matter obtained by filtering the solution can be dried and fired to obtain the exhaust gas purifying catalyst powder according to the present invention.
また、本発明の排ガス浄化触媒の製造の際には、上述したように複合酸化物の焼成工程を省略することができる。つまり、貴金属原料溶液と希土類元素原料溶液とを混合し、貴金属と希土類元素とを含む複合酸化物前駆体を沈殿させた後、この沈殿物と耐熱性酸化物原料溶液を混合して当該沈殿物の周りに酸化物粒子前駆体を形成させて沈殿させた後、ろ過、乾燥、焼成する工程を経て製造することができる。複合酸化物前駆体として例えばＰｄＯとＬｎ２Ｏ３との複合酸化物を前駆体の状態で耐熱性酸化物原料溶液中に入れ、液中で分散させながら耐熱性酸化物の前駆体を形成させることにより、複合酸化物前駆体と耐熱性酸化物前駆体とが高分散した状態で混合でき、よって熱耐久性がより向上した排ガス浄化用触媒粉末を得ることができる。 Further, when the exhaust gas purification catalyst of the present invention is manufactured, the firing step of the composite oxide can be omitted as described above. That is, after mixing the noble metal raw material solution and the rare earth element raw material solution to precipitate a composite oxide precursor containing the noble metal and the rare earth element, the precipitate and the refractory oxide raw material solution are mixed to produce the precipitate. After the oxide particle precursor is formed and precipitated around the substrate, it can be manufactured through filtration, drying and firing. As a composite oxide precursor, for example, a composite oxide of PdO and Ln 2 O 3 is put in a precursor in a heat-resistant oxide raw material solution, and a precursor of a heat-resistant oxide is formed while being dispersed in the liquid. As a result, it is possible to obtain a catalyst powder for exhaust gas purification that can be mixed in a state in which the complex oxide precursor and the heat-resistant oxide precursor are highly dispersed, thereby further improving the heat durability.
本発明の排ガス浄化触媒の製造方法においては、上述した工程以外の工程については、常法に従って行うことができ、得られた排ガス浄化用触媒粉末をスラリにして、ハニカム基体の内壁面の表面に塗布形成して、実機に供される。 In the method for producing an exhaust gas purification catalyst of the present invention, steps other than those described above can be performed according to a conventional method, and the obtained exhaust gas purification catalyst powder is made into a slurry on the inner wall surface of the honeycomb substrate. After coating and forming, it is provided to the actual machine.
［実施例１］
実施例１は、PdとNdとの複合酸化物を有する例である。
[Example 1]
Example 1 is an example having a composite oxide of Pd and Nd.
水2000ｇに、硝酸ネオジムNd（NO3）3・6H2Oを175.336ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を400℃で1時間焼成して、複合酸化物粉末（これを「粉末１ａ」と呼ぶ）とした。 Add 175.336 g of neodymium nitrate Nd (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%) to 2000 g of water, mix, and then stir with 25% aqueous ammonia solution Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 400 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 1a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを1994ｇと、上記粉末１ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 5000 g of water, 1994 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 1a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例２］
実施例２は、PdとSmとの複合酸化物を有する例である。
[Example 2]
Example 2 is an example having a composite oxide of Pd and Sm.
水2000ｇに、硝酸サマリウムSm（NO3）3・6H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を400℃で1時間焼成して、複合酸化物粉末（これを「粉末２ａ」と呼ぶ）とした。 After adding 177.784g of samarium nitrate Sm (NO 3 ) 3 · 6H 2 O and 101.221g of palladium nitrate solution (Pd: 20.764wt%) to 2000g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 400 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 2a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを2048ｇと、上記粉末２ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 5000 g of water, 2048 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 2a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例３］
実施例３は、PdとGdとの複合酸化物を有する例である。
[Example 3]
Example 3 is an example having a composite oxide of Pd and Gd.
水2000ｇに、硝酸ガドリニウムGd（NO3）3・5H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を400℃で1時間焼成して、複合酸化物粉末（これを「粉末３ａ」と呼ぶ）とした。 After adding 177.784g of gadolinium nitrate Gd (NO 3 ) 3 · 5H 2 O and 101.221g of palladium nitrate solution (Pd: 20.764wt%) to 2000g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 400 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 3a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを2109ｇと、上記粉末３ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 After adding 2109 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 3a to 5000 g of water and mixing them, a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例４］
実施例４は、PdとLaとの複合酸化物を有する例である。
[Example 4]
Example 4 is an example having a composite oxide of Pd and La.
水2000ｇに、硝酸ランタンLa（NO3）3・6H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を400℃で1時間焼成して、複合酸化物粉末（これを「粉末４ａ」と呼ぶ）とした。 After adding 177.784 g of lanthanum nitrate La (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%) to 2000 g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 400 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 4a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを1947ｇと、上記粉末４ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 Into 5000 g of water, 1947 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the above powder 4a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例５］
実施例５は、PdとNdとの複合酸化物を有する例であり、実施例１とは、複合酸化物の焼成温度が異なる例である。
[Example 5]
Example 5 is an example having a complex oxide of Pd and Nd, and Example 1 is an example in which the firing temperature of the complex oxide is different.
水2000ｇに、硝酸ネオジムNd（NO3）3・6H2Oを175.336ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を700℃で1時間焼成して、複合酸化物粉末（これを「粉末１ｂ」と呼ぶ）とした。 Add 175.336 g of neodymium nitrate Nd (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%) to 2000 g of water, mix, and then stir with 25% aqueous ammonia solution Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 700 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 1b”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを1994ｇと、上記粉末１ｂとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 5000 g of water, 1994 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 1b were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例６］
実施例６は、PdとSmとの複合酸化物を有する例であり、実施例２とは、複合酸化物の焼成温度が異なる例である。
[Example 6]
Example 6 is an example having a composite oxide of Pd and Sm, and Example 2 is an example in which the firing temperature of the composite oxide is different.
水2000ｇに、硝酸サマリウムSm（NO3）3・6H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を700℃で1時間焼成して、複合酸化物粉末（これを「粉末２ｂ」と呼ぶ）とした。 After adding 177.784g of samarium nitrate Sm (NO 3 ) 3 · 6H 2 O and 101.221g of palladium nitrate solution (Pd: 20.764wt%) to 2000g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 700 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 2b”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを2048ｇと、上記粉末２ｂとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 5000 g of water, 2048 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 2b were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例７］
実施例７は、PdとGdとの複合酸化物を有する例であり、実施例３とは、複合酸化物の焼成温度が異なる例である。
[Example 7]
Example 7 is an example having a composite oxide of Pd and Gd, and Example 7 is an example in which the firing temperature of the composite oxide is different.
水2000ｇに、硝酸ガドリニウムGd（NO3）3・5H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を700℃で1時間焼成して、複合酸化物粉末（これを「粉末３ｂ」と呼ぶ）とした。 After adding 177.784g of gadolinium nitrate Gd (NO 3 ) 3 · 5H 2 O and 101.221g of palladium nitrate solution (Pd: 20.764wt%) to 2000g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 700 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 3b”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを2109ｇと、上記粉末３ｂとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 After adding 2109 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 3b to 5000 g of water and mixing them, a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例８］
実施例８は、PdとLaとの複合酸化物を有する例であり、実施例４とは、複合酸化物の焼成温度が異なる例である。
[Example 8]
Example 8 is an example having a composite oxide of Pd and La, and Example 4 is an example in which the firing temperature of the composite oxide is different.
水2000ｇに、硝酸ランタンLa（NO3）3・6H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を700℃で1時間焼成して、複合酸化物粉末（これを「粉末４ｂ」と呼ぶ）とした。 After adding 177.784 g of lanthanum nitrate La (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%) to 2000 g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 700 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 4b”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを1947ｇと、上記粉末４ｂとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 Into 5000 g of water, 1947 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 4b were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例9］
実施例９はPdとNdとの複合酸化物を有する例であり、複合酸化物前駆体の焼成を行わない点で実施例１と相違する例である。
[Example 9]
Example 9 is an example having a composite oxide of Pd and Nd, and is an example different from Example 1 in that the composite oxide precursor is not fired.
水2000ｇに、硝酸ネオジムNd（NO3）3・6H2Oを175.336ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨て、複合水酸化物ケーキ（これを「ケーキ１ａ」と呼ぶ）とした。 Add 175.336 g of neodymium nitrate Nd (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%) to 2000 g of water, mix, and then stir with 25% aqueous ammonia solution Was added dropwise until pH 11 was reached. Next, the mixture was filtered and washed with water, and the supernatant was discarded to obtain a composite hydroxide cake (referred to as “cake 1a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを1994ｇと、上記ケーキ１ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 5000 g of water, 1994 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the cake 1a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例１０］
実施例１０はPdとSmとの複合酸化物を有する例であり、複合酸化物前駆体の焼成を行わない点で実施例２と相違する例である。
[Example 10]
Example 10 is an example having a composite oxide of Pd and Sm, and is an example different from Example 2 in that the composite oxide precursor is not fired.
水2000ｇに、硝酸サマリウムSm（NO3）3・6H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨て、複合水酸化物ケーキ（これを「ケーキ２ａ」と呼ぶ）とした。 After adding 177.784g of samarium nitrate Sm (NO 3 ) 3 · 6H 2 O and 101.221g of palladium nitrate solution (Pd: 20.764wt%) to 2000g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Next, the mixture was filtered and washed with water, and the supernatant was discarded to obtain a composite hydroxide cake (referred to as “cake 2a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを2048ｇと、上記ケーキ２ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 5000 g of water, 2048 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the cake 2a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例１１］
実施例１１はPdとGdとの複合酸化物を有する例であり、複合酸化物前駆体の焼成を行わない点で実施例３と相違する例である。
[Example 11]
Example 11 is an example having a composite oxide of Pd and Gd, and is an example different from Example 3 in that the composite oxide precursor is not fired.
水2000ｇに、硝酸ガドリニウムGd（NO3）3・5H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨て、複合水酸化物ケーキ（これを「ケーキ３ａ」と呼ぶ）とした。 After adding 177.784g of gadolinium nitrate Gd (NO 3 ) 3 · 5H 2 O and 101.221g of palladium nitrate solution (Pd: 20.764wt%) to 2000g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Next, the mixture was filtered and washed with water, and the supernatant was discarded to obtain a composite hydroxide cake (referred to as “cake 3a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを2109ｇと、上記ケーキ３ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 Into 5000 g of water, 2109 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the cake 3a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［実施例１２］
実施例１２はPdとLaとの複合酸化物を有する例であり、複合酸化物前駆体の焼成を行わない点で実施例４と相違する例である。
[Example 12]
Example 12 is an example having a composite oxide of Pd and La, and is an example different from Example 4 in that the composite oxide precursor is not fired.
水2000ｇに、硝酸ランタンLa（NO3）3・6H2Oを177.784ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨て、複合水酸化物ケーキ（これを「ケーキ４ａ」と呼ぶ）とした。 After adding 177.784 g of lanthanum nitrate La (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%) to 2000 g of water and mixing, 25% aqueous ammonia solution with stirring Was added dropwise until pH 11 was reached. Next, the mixture was filtered and washed with water, and the supernatant was discarded to obtain a composite hydroxide cake (referred to as “cake 4a”).
水5000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを1947ｇと、上記ケーキ４ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 Into 5000 g of water, 1947 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the above cake 4a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［比較例１］
比較例１は、PdとNdとの複合酸化物を有する例であるが、Nd量がPd量に対して相対的に少ないため、Nd４PdO７を含有しない例である。
[Comparative Example 1]
Comparative Example 1 is an example having a composite oxide of Pd and Nd, but is an example not containing Nd 4 PdO 7 because the Nd amount is relatively small with respect to the Pd amount.
水2000ｇに、硝酸ネオジムNd（NO3）3・6H2Oを43.834ｇと、硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、攪拌しながら25％アンモニア水溶液をpH 11となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥後の粉末を400℃で1時間焼成して、複合酸化物粉末（これを「粉末５ａ」と呼ぶ）とした。 After mixing and mixing 2000 g of water with 43.834 g of neodymium nitrate Nd (NO 3 ) 3 · 6H 2 O and 101.221 g of palladium nitrate solution (Pd: 20.764 wt%), 25% ammonia aqueous solution with stirring Was added dropwise until pH 11 was reached. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The dried powder was fired at 400 ° C. for 1 hour to obtain a composite oxide powder (referred to as “powder 5a”).
水2000ｇに、硝酸アルミニウムAl（NO3）3・9H2Oを880ｇと、上記粉末５ａとを投入し、混合した後、攪拌しながら25％アンモニア水溶液をpH 9となるまで滴下した。次いで、濾過、水洗し、上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、複合酸化物粉末の周辺にAl2O3を配した粉末とした。 To 2000 g of water, 880 g of aluminum nitrate Al (NO 3 ) 3 .9H 2 O and the powder 5a were added and mixed, and then a 25% aqueous ammonia solution was added dropwise to pH 9 while stirring. Subsequently, after filtration and washing with water, the supernatant was discarded, and then left in a constant temperature bath at 150 ° C. for 24 hours to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain a powder in which Al 2 O 3 was arranged around the composite oxide powder.
［比較例２］
比較例２は、PdとNｄの複合酸化物を有しない例である。
[Comparative Example 2]
Comparative Example 2 is an example not having a composite oxide of Pd and Nd.
水2000ｇに、酸化アルミニウムAl2O3を279ｇと硝酸パラジウム溶液（Pd：20.764wt%）を101.221ｇとを投入して混合した後、5時間攪拌した。次いで上澄み液を捨てた後、150℃の恒温槽内で一昼夜放置して水分を蒸発させた。乾燥して得られた粉末を400℃で1時間焼成し、Pdを担持したAl2O3粉末とした。 2,000 g of water was mixed with 279 g of aluminum oxide Al 2 O 3 and 101.221 g of a palladium nitrate solution (Pd: 20.764 wt%), and then stirred for 5 hours. Next, after the supernatant was discarded, it was left in a constant temperature bath at 150 ° C. for one day to evaporate water. The powder obtained by drying was fired at 400 ° C. for 1 hour to obtain Al 2 O 3 powder supporting Pd.
以上述べた工程により得られた実施例１〜１２、比較例１〜２の各触媒粉末180ｇと、ベーマイト18ｇと、10%硝酸含有水溶液565ｇとをアルミナ製磁性ポットに投入し、アルミナボールと共に振とう粉砕して触媒スラリを得た。更に、この触媒スラリを、0.119Lのコージェライト製ハニカム基材（400セル／4ミル）に投入して空気気流中にて余剰スラリを除去した後120℃にて乾燥し、更に空気気流中にて400℃で焼成してハニカム基材に触媒粉末をコーティングしたて、実施例1〜12、比較例1〜2の触媒を得た。このとき得られた触媒担持ハニカムにコートされた触媒量は、触媒１Lあたり220ｇである。触媒１L当りに含まれるPd量は 14gであった。 180 g of each of the catalyst powders of Examples 1 to 12 and Comparative Examples 1 and 2 obtained by the steps described above, 18 g of boehmite, and 565 g of a 10% nitric acid-containing aqueous solution were put into an alumina magnetic pot and shaken with alumina balls. After pulverization, a catalyst slurry was obtained. Furthermore, this catalyst slurry was put into a 0.119 L cordierite honeycomb substrate (400 cells / 4 mil) to remove excess slurry in an air stream, dried at 120 ° C., and further into the air stream The catalyst of Examples 1-12 and Comparative Examples 1-2 was obtained by firing at 400 ° C. and coating the honeycomb substrate with the catalyst powder. The amount of catalyst coated on the catalyst-supporting honeycomb obtained at this time is 220 g per liter of catalyst. The amount of Pd contained per liter of catalyst was 14 g.
これらの各触媒は、以下の方法によって評価された。 Each of these catalysts was evaluated by the following method.
＜触媒耐久試験＞
日産自動車製Ｖ型６気筒、排気量3500ccのエンジンにおいて、触媒入口温度1000℃に設定し、30時間にわたって耐久試験を行った。なお、燃料として無鉛ガソリンを使用した。耐久試験後の触媒のユニットの大ききを、ＴＥＭにより計測した。
<Catalyst durability test>
An endurance test was conducted for 30 hours using a Nissan V-type 6-cylinder engine with a displacement of 3500 cc and a catalyst inlet temperature of 1000 ° C. In addition, unleaded gasoline was used as fuel. The size of the catalyst unit after the durability test was measured by TEM.
＜触媒評価試験＞
上記耐久を施した触媒担体を一部くり抜き触媒容量を40mLとして、触媒評価を行った。反応ガスの組成は表１に示す条件、反応ガス流量40L/分で反応ガスを供給し、触媒温度が各温度におけるHC成分の定常状態での浄化率を測定した。また、浄化性能は、HCの浄化率が５０パーセントなる温度（HC-T50）により評価した。
The catalyst was evaluated by setting a part of the catalyst carrier having the above durability to 40 mL. The reaction gas was supplied under the conditions shown in Table 1 under the reaction gas flow rate of 40 L / min, and the purification rate in the steady state of the HC component at each catalyst temperature was measured. The purification performance was evaluated by the temperature (HC-T50) at which the purification rate of HC becomes 50%.
＜触媒浄化性能＞
表２に、実施例1〜12、比較例1、２のHCの50％浄化温度（HC-T50）と複合酸化物ユニットの粒径を示す。
Table 2 shows the 50% purification temperature (HC-T50) of HC of Examples 1 to 12 and Comparative Examples 1 and 2 and the particle size of the composite oxide unit.
実施例1と比較例１、２を比較すると実施例1は1000℃耐久後もＬｎ４ＰｄＯ７を含む複合酸化物であるＬｎ４ＰｄＯｘの複合酸化物が安定相であるため耐久後も微細な複合酸化物を維持し、HC-T50が低い値となった。一方、比較例１はPdに対してLnとしてのNdが不足しており1000℃耐久後ではPdOとLn2Pd2O5に分解し、耐久後のHC-T50が高い値となった。また、比較例2は比較例1と同様に1000℃耐久後にPdOの粒凝集により、耐久後のHC-T50が高い値となった。 Comparing Example 1 with Comparative Examples 1 and 2, Example 1 is fine even after endurance because the composite oxide of Ln 4 PdO x which is a composite oxide containing Ln 4 PdO 7 is a stable phase even after endurance at 1000 ° C. HC-T50 was low. On the other hand, in Comparative Example 1, Nd as Ln was insufficient with respect to Pd and decomposed into PdO and Ln2Pd2O5 after 1000 ° C. endurance, and HC-T50 after endurance was high. In Comparative Example 2, as in Comparative Example 1, the HC-T50 after durability was high due to the aggregation of PdO particles after 1000 ° C durability.
実施例2〜4は、実施例１と同様に1000℃耐久後もLn4PdOｘが安定相であるため耐久後も微細な複合酸化物を維持し、HC-T50が低い値となった。 In Examples 2 to 4, as in Example 1, Ln4PdOx was a stable phase even after durability at 1000 ° C., so that a fine composite oxide was maintained after durability and HC-T50 was low.
実施例5〜8は、実施例1〜4と比較し複合酸化物の粒径が大きく、耐久後のHC-T50が実施例1〜4よりも相対的に高い値となった。 In Examples 5 to 8, the particle size of the composite oxide was larger than those in Examples 1 to 4, and the HC-T50 after durability was relatively higher than that in Examples 1 to 4.
実施例9〜12は、実施例1〜4と同様に1000℃耐久後もLn4PdO7が安定相であるため耐久後も微細な複合酸化物を維持し、HC-T50が低い値となった。 In Examples 9 to 12, Ln4PdO7 was a stable phase even after 1000 ° C. endurance as in Examples 1 to 4, so that a fine composite oxide was maintained after endurance and HC-T50 was low.
１ 複合酸化物
２ 耐熱性酸化物
1
Claims (6)
前記複合酸化物が、前記貴金属としてのＰｄと前記希土類元素としてのランタノイドＬｎとの複合酸化物であるＬｎ ４ ＰｄＯ ７ を含み、前記Ｌｎ ４ ＰｄＯ ７ を含む複合酸化物の周囲に前記耐熱性酸化物が配置され、
前記複合酸化物Ｌｎ ４ ＰｄＯ ７ の粒子径が１ｎｍ〜５００ｎｍであり、
前記複合酸化物同士が、この耐熱性酸化物により隔てられた構造のユニットを含むことを特徴とする排ガス浄化触媒。 It includes a composite oxide containing a noble metal and rare earth elements, and heat-resistant oxide, and,
The composite oxide includes Ln 4 PdO 7 , which is a composite oxide of Pd as the noble metal and lanthanoid Ln as the rare earth element, and the heat-resistant oxidation around the composite oxide containing Ln 4 PdO 7 Things are placed,
The composite oxide Ln 4 PdO 7 has a particle diameter of 1 nm to 500 nm,
An exhaust gas purifying catalyst, wherein the complex oxide includes a unit having a structure separated by the heat-resistant oxide.
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