JP3777696B2 - Metal fine particle supported oxide catalyst - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、排ガス浄化用触媒に関し、特に触媒活性種と酸化し易い金属元素からなる合金を酸化処理することにより、触媒活性種微粒子が均一に分散した金属酸化物触媒に関する。
【０００２】
【従来の技術】
従来より、自動車等の排ガス浄化用触媒の触媒成分としては、Ｐｔ，Ｐｄ，Ｒｈ等の貴金属が単独または組み合わせて用いられており、通常、触媒担体に担持された構成とされている。一方、排ガス浄化用触媒としての既存の超微粒子金触媒は、金粒子径が１０ｎｍ以上では触媒活性を示さない。そのため、粒子径１０ｎｍ未満の金粒子を得るには、担体（金属酸化物・金属化合物）上に沈澱する水酸化金やメタル金のサイズの制御、および乾燥や熱処理時の粒子成長を抑制することが重要となる。
【０００３】
例えば特開昭６４−８３５１３号公報では、アルカリ土類金属化合物に金超微粒子を固定した酸化触媒および還元触媒並びに可燃性ガスセンサ素子とそれらの製造方法が開示されている。この方法においては、溶液のｐＨの制御、中和剤や還元剤の検討、乾燥や熱処理の検討等が行われ、これらは複雑な製造工程となっている。また、担体（金属酸化物・金属化合物）の種類によっては、粒子径１０ｎｍ未満の金粒子を得ることが困難な場合もある。
上記の方法により得られた金触媒は優れた酸化活性を示すが、ガス空間速度が20000hr -1と低く大量の排気ガスを処理するには実用的ではない。
さらに、欧州ステップIII 規制やλ＝１規制等の排気規制強化への対応により、排気温度が上昇するため、触媒の耐熱性向上が要求されている。現行のＰｔ／Ａｌ2 ０3 系触媒では、高温でのリーン雰囲気下で著しく浄化性能が低下する傾向にある。
このように、最近の各種排ガス規制に対応できる触媒成分としての超微粒子金を比較的簡便な製造工程によって製造し、さらに触媒活性を改善する技術開発が望まれていた。
【０００４】
【発明が解決しようとする課題】
本発明の目的は、従来の金属微粒子担持酸化物触媒では、溶液調整等が煩瑣であったが、これを簡便な工程として合金ないし金属化合物の熱処理によって製造可能とし、金属微粒子が均一に分散した金属微粒子担持酸化物触媒を提供することにある。
また、本発明の他の目的は、触媒活性種と金属元素との組み合わせを使用環境から検討し、触媒活性種が析出して存在できる熱処理条件を選択することによって、金属微粒子が均一に分散した金属微粒子担持酸化物触媒を提供することにある。
【０００５】
さらに、本発明の別の目的は、前記金属化合物をモノリス等の構造物に溶着し熱処理することによって、金属微粒子担持酸化物触媒のコート層を形成可能とする金属微粒子担持酸化物触媒層の製造方法を提供することにある。
【０００６】
【課題を解決するための手段】
上記の目的は、Ａｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓから選ばれる１種または２種以上の元素と、下記に示す金属Ｍから選ばれる１種または２種以上の元素とで構成される、金属間化合物または金属のみから成る固溶体を、酸素を含有する雰囲気で熱処理して製造されることを特徴とする金属微粒子担持酸化物から成る排ガス浄化用触媒によって達成される。
Ｍ：Ｓｒ，Ｎｂ，Ｌｉ，Ｌａ，Ａｌ，Ｓｉ，Ｍｇ，Ｃａ，Ｂａ，Ｃｅ，Ｎｄ，Ｔｉ，Ｆｅ，Ｃｏ，Ｎｉ，Ｃｕ，Ｚｎ，Ｚｒ，Ｖ，Ｔａ，Ｃｒ，Ｍｏ，Ｗ，Ｎａ，Ｋ，Ｂｅ，Ｓｃ，Ｙ，Ｉｎ，Ｓｎ，Ｐｂ，Ｂｉ．
【０００７】
また、上記の目的は、前記金属化合物の形態が金属間化合物、または固溶体である金属微粒子担持酸化物触媒によっても達成される。
さらに、上記の目的は、前記金属化合物を単独に、または前記金属化合物と前記金属Ｍの塩から選ばれる１種または２種以上の混合物を、酸素を含有する雰囲気で熱処理して製造されることを特徴とする金属微粒子担持酸化物触媒によっても達成される。
【０００８】
【発明の実施の形態】
本発明では、金属原子が酸化物内を拡散し、表面に析出して金属粒子を形成するため、金属粒子は担体と強固に接合しており、従来の触媒より耐熱性に優れる。従来の溶液を用いて触媒を製造する場合と比べて、触媒金属の歩留り・担持効率が向上する。例えば、従来のＴｉＯ2 へジニトロジアミンＰｔ水溶液を用いてＰｔを担持する場合、非常に担持効率が悪いが、本発明では、金属化合物中のＰｔ全量が粒子となるため担持効率がよい。また、製造方法が簡便なため低コストであり、製造工程中の取扱が容易となる。
【０００９】
本発明の第１発明では、触媒活性種としてＡｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓは、金属化合物を構成する金属Ｍの酸化物中に均一に分散した構造であるため、触媒活性が向上する。すなわち、金属元素Ｍ（Ｓｒ，Ｎｂ，Ｌｉ，Ｌａ，Ａｌ，Ｓｉ，Ｍｇ，Ｃａ，Ｂａ，Ｃｅ，Ｎｄ，Ｔｉ，Ｆｅ，Ｃｏ，Ｎｉ，Ｃｕ，Ｚｎ，Ｚｒ，Ｖ，Ｔａ，Ｃｒ，Ｍｏ，Ｗ，Ｎａ，Ｋ，Ｂｅ，Ｓｃ，Ｙ，Ｉｎ，Ｓｎ，Ｐｂ，Ｂｉ）は、熱処理により酸化物となり、担体や助触媒として働くものである。
【００１０】
この場合、金属化合物を単独に、または前記金属Ｍの塩から選ばれる１種または２種以上の混合物を、酸素を含有する雰囲気で熱処理して製造されてもよく、触媒活性種と金属元素Ｍの組み合わせには制約はないが、触媒の使用雰囲気に応じて組み合わせるのが望ましい。例えば、水分の多い環境で使用する場合は、アルカリ金属以外を選択すればよい。また、不安定な複合酸化物を形成する組み合わせは、触媒性能を劣化させるため避ける方が望ましい。
また、第２発明においては、金属化合物の形態が金属間化合物、または固溶体とするものである。触媒活性種と金属元素Ｍの組み合わせの比率（組成比）は、触媒活性種と金属元素Ｍが全率固溶するか否かで異なる。全率固溶する場合は、任意でよい。全率固溶しない場合は、金属間化合物を形成する組成比か、または、固溶限内にする。金属間化合物および固溶体は、触媒活性種であるＡｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓが、原子レベルで均一に存在するため、熱処理により析出する粒子が微細かつ均一分散する。一方、金属間化合物および固溶体以外の組成比の化合物は、Ａｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓが化合物内に不均一に存在するため、熱処理により析出する粒子が粗大かつ不均一分散となり、触媒活性を示さない。
【００１１】
上記元素以外に、熱処理時に微粒子として析出して触媒活性を示す元素は、触媒活性種として用いることが可能である。また、酸化物を形成する元素は、金属元素Ｍとして用いることが可能である。
Ａｕは、酸素との親和性が低く、酸化物や金属元素Ｍと複合酸化物を形成しないため、触媒活性種として望ましい。
本発明の第３発明においては、金属化合物内のＡｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓ量が所定の担持量の場合、金属化合物を単独で熱処理すればよい。一方、所定の担持量でない場合、その金属化合物に含まれる金属元素Ｍの塩を混合して熱処理を行うものである。塩の種類は、熱処理により酸化物となるものであればよい。
【００１２】
本発明の金属元素Ｍは、触媒活性種であるＡｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓより酸化物を生成し易いアルカリ土類金属、ランタノイド、遷移金属が望ましい。アルカリ土類金属の酸化物が、触媒として促進する反応はＨ+ を分子状態から分離することによって、反応自体が開始するものであり、ランタノイドの複合酸化物としては、ペロブスカイト構造のものでは、ＮＯの還元および酸化反応も行われており、特に酸化反応ではその活性は大きい。
本発明の金属微粒子担持酸化物触媒の製造方法について説明する。
金属化合物は、従来用いられている高周波溶解、アーク溶解等の鋳造方法でよい。酸化物を形成し易い元素を含む場合は、真空または不活性雰囲気で溶解・鋳造するのが望ましい。鋳塊の形状は、インゴットでも粉末でもよい。ただし、インゴットの場合は、熱処理の前に粉砕する。
【００１３】
本発明の熱処理温度・時間に制約はないが、析出した金属微粒子の成長を抑制するために、温度５００〜１２００℃、時間５〜１００ｈｒが望ましい。
本熱処理は、酸素を含む雰囲気中で行うものである。この熱処理により、金属元素Ｍは酸化物となる。酸化物にならないＡｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓは、酸化物中を拡散して微粒子を形成する。このようにして形成した微粒子は、酸化物と強固に接合し、かつ均一に分散している。微粒子と酸化物が強固に接合しているためインタラクションが強くなり触媒活性が向上すると考えられる。
本発明の他の使用形態として、上記金属化合物を原子レベルでモノリス等の構造物に溶着し、酸素を含む雰囲気中で熱処理を行うと、コート層である金属化合物中の金属元素Ｍは酸化物となる。酸化物にならないＡｕ，Ｐｔ，Ｐｄ，Ｒｈ，Ａｇ，Ｉｒ，Ｒｕ，Ｏｓは、酸化物中を拡散して微粒子を形成する。このようにして形成された金属微粒子担持酸化物触媒のコート層は、モノリス等の構造物表面に強固に接合しているため剥離しにくい。
【００１４】
この時、溶着をＰＶＤ（プラズマ蒸着），ＣＶＤ（化学蒸着）を用いると、従来のスラリーを用いた方法では担持が不可能な形状の構造物にも触媒層をコートすることが可能となる。溶着は、構造物だけでなくＡｌ2 Ｏ3 等の粉末上に行ってもよい。
以下に本発明について実施例に基づいてさらに詳述する。
【００１５】
【実施例】
実施例１
アルゴンガス雰囲気中で高周波溶解を用いてＡｕＳｒ金属間化合物（ＡｕとＳｒのモル比１：１）を溶解鋳造した。ＡｕＳｒ金属間化合物を粉砕後、ＡｕＳｒ金属間化合物：２５ｇとＳｒ（ＯＨ）2 ・８Ｈ2 Ｏ：２８ｇの混合物を、大気中で６５０℃×１２０時間の熱処理を行った。熱処理により得られたＡｕ粒子径３４ｎｍのＡｕ／ＳｒＯ粉末にγ−Ａｌ2 Ｏ3 粉末を混合し、Ａｕ量０．５ｗｔ％のＡｕ／ＳｒＯ／Ａｌ2 Ｏ3 触媒Ａを得た。粒子径および定性分析はＸＲＤ（Ｘ線回折）を、組成分析は蛍光Ｘ線分析を用いた。
【００１６】
実施例２
アルゴンガス雰囲気中で高周波溶解を用いてＬａ2 Ａｕ金属間化合物（ＡｕとＬａのモル比１：２）を溶解鋳造した。Ｌａ2 Ａｕ金属間化合物を粉砕後、Ｌａ2 Ａｕ金属間化合物を、大気中で７５０℃×３０時間の熱処理を行った。熱処理により得られたＡｕ粒子径５４ｎｍのＡｕ／Ｌａ2 Ｏ3 粉末にγ−Ａｌ2 Ｏ3 粉末を混合し、Ａｕ量２ｗｔ％のＡｕ／Ｌａ2 Ｏ3 ／Ａｌ2 Ｏ3 触媒Ｂを得た。粒子径および定性分析はＸＲＤ（Ｘ線回折）を、組成分析は蛍光Ｘ線分析を用いた。
【００１７】
比較例１
ＨＡｕＣｌ4 水溶液（５×１０-3ｍｏｌ／ｌ）にγ−Ａｌ2 Ｏ3 粉末を添加し、３時間攪拌した後、大気中で１２０℃×２４時間の乾燥を行った。乾燥後、大気中で５００℃×２時間の熱処理を行い、Ａｕ粒子径４２ｎｍ、Ａｕ量２ｗｔ％のＡｕ／Ａｌ2 Ｏ3 触媒Ｃを得た。なお、粒子径および定性分析はＸＲＤ（Ｘ線回折）を、組成分析は蛍光Ｘ線分析を用いた。
次に、実施例１、２で得られた触媒Ａ，Ｂおよび比較例１で得られた触媒Ｃについて常圧流通式反応装置を使用して、浄化率を測定した。この時の浄化率測定ガスは、表１に示すガス組成で、 No.１をリーン組成とし、 No.２をストイキ相当組成として、ガス空間速度150,000h-1にて触媒活性を評価した。
【００１８】
【表１】
各触媒床温度を５００℃まで上昇させ、４００℃、３００℃、２００℃と段階的に温度を低下させて、各温度で定常状態での浄化率を測定した。この時の浄化率の定義は下記のとおりである。
浄化率＝〔（入ガス濃度−出ガス濃度）／入ガス濃度〕×１００
上記の測定結果について表２に合わせて示す。
【００２０】
【表２】
この結果から、本発明である No.１〜４は、測定全温度でのＣＯおよびＨＣについての浄化率が、またＮＯの最大浄化率において、比較例の No.５、６と比較して優れた触媒活性を示していることがわかる。
【００２２】
【発明の効果】
本発明によれば、表面に析出する金属粒子が担体と強固に接合し触媒としての耐熱性に優れる。また、溶液を用いて触媒を製造する場合と比べて、触媒金属の歩留り・担持効率が向上する。さらに、製造方法が簡便なため低コストであり、作業中の取扱が容易である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust gas purifying catalyst, and more particularly to a metal oxide catalyst in which fine particles of catalytically active species are uniformly dispersed by oxidizing an alloy composed of catalytically active species and easily oxidizable metal elements.
[0002]
[Prior art]
Conventionally, noble metals such as Pt, Pd, and Rh have been used singly or in combination as catalyst components of exhaust gas purification catalysts for automobiles, and are usually configured to be supported on a catalyst carrier. On the other hand, existing ultrafine gold catalysts as exhaust gas purification catalysts do not exhibit catalytic activity when the gold particle diameter is 10 nm or more. Therefore, in order to obtain gold particles having a particle diameter of less than 10 nm, control of the size of gold hydroxide or metal gold precipitated on the carrier (metal oxide / metal compound) and suppression of particle growth during drying or heat treatment are required. Is important.
[0003]
For example, Japanese Patent Application Laid-Open No. 64-83513 discloses an oxidation catalyst and a reduction catalyst in which gold ultrafine particles are fixed to an alkaline earth metal compound, a combustible gas sensor element, and a method for producing them. In this method, control of the pH of the solution, examination of a neutralizing agent and a reducing agent, examination of drying and heat treatment, and the like are performed, and these are complicated manufacturing processes. In addition, depending on the type of carrier (metal oxide / metal compound), it may be difficult to obtain gold particles having a particle diameter of less than 10 nm.
Although the gold catalyst obtained by the above method exhibits excellent oxidation activity, the gas space velocity is as low as 20000 hr −1, and it is not practical for treating a large amount of exhaust gas.
Furthermore, since the exhaust temperature rises due to the compliance with the exhaust emission regulations such as the European Step III regulation and the λ = 1 regulation, the heat resistance of the catalyst is required to be improved. In the current Pt / Al 2 0 3 catalyst, the purification performance tends to be remarkably lowered in a lean atmosphere at a high temperature.
As described above, it has been desired to develop a technique for producing ultrafine gold as a catalyst component capable of complying with recent various exhaust gas regulations by a relatively simple production process and further improving the catalytic activity.
[0004]
[Problems to be solved by the invention]
The object of the present invention is that the conventional fine metal particle-supported oxide catalyst requires troublesome solution adjustment, but this can be produced by a heat treatment of an alloy or metal compound as a simple process, and the fine metal particles are uniformly dispersed. The object is to provide a metal fine particle supported oxide catalyst.
Another object of the present invention is to examine the combination of the catalytically active species and the metal element from the usage environment, and by selecting the heat treatment conditions in which the catalytically active species can be deposited, the metal fine particles are uniformly dispersed. The object is to provide a metal fine particle supported oxide catalyst.
[0005]
Furthermore, another object of the present invention is to produce a metal fine particle-supported oxide catalyst layer capable of forming a coat layer of a metal fine particle-supported oxide catalyst by welding the metal compound to a structure such as a monolith and heat-treating it. It is to provide a method.
[0006]
[Means for Solving the Problems]
The above objects, Au, Pt, Pd, Rh , Ag, Ir, Ru, and one or more elements selected from Os, and one or more elements selected from the metal M shown below It is achieved by an exhaust gas purifying catalyst comprising a fine metal particle-supported oxide, which is produced by heat-treating a solid solution composed of only an intermetallic compound or a metal in an atmosphere containing oxygen.
M: Sr, Nb, Li, La, Al, Si, Mg, Ca, Ba, Ce, Nd, Ti, Fe, Co, Ni, Cu, Zn, Zr, V, Ta, Cr, Mo, W, Na, K, Be, Sc, Y, In, Sn, Pb, Bi.
[0007]
The above object can also be achieved by a metal fine particle supported oxide catalyst in which the form of the metal compound is an intermetallic compound or a solid solution.
Furthermore, the above object is produced by heat-treating the metal compound alone or one or a mixture of two or more selected from the metal compound and the metal M salt in an oxygen-containing atmosphere. It is also achieved by a metal fine particle supported oxide catalyst characterized by the following.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, since metal atoms diffuse in the oxide and precipitate on the surface to form metal particles, the metal particles are firmly bonded to the support and have better heat resistance than conventional catalysts. Compared with the case where a catalyst is produced using a conventional solution, the yield / support efficiency of the catalyst metal is improved. For example, when Pt is supported on conventional TiO 2 using a dinitrodiamine Pt aqueous solution, the supporting efficiency is very poor. However, in the present invention, the total amount of Pt in the metal compound becomes particles, so the supporting efficiency is good. Moreover, since the manufacturing method is simple, the cost is low, and handling during the manufacturing process becomes easy.
[0009]
In the first invention of the present invention, Au, Pt, Pd, Rh, Ag, Ir, Ru, and Os as catalytically active species have a structure that is uniformly dispersed in the oxide of metal M constituting the metal compound. Catalytic activity is improved. That is, the metal element M (Sr, Nb, Li, La, Al, Si, Mg, Ca, Ba, Ce, Nd, Ti, Fe, Co, Ni, Cu, Zn, Zr, V, Ta, Cr, Mo, W, Na, K, Be, Sc, Y, In, Sn, Pb, Bi) are converted into oxides by heat treatment and serve as carriers and promoters.
[0010]
In this case, the metal compound may be produced by heat-treating the metal compound alone or a mixture of two or more kinds selected from the salts of the metal M in an oxygen-containing atmosphere. Although there is no restriction | limiting in this combination, It is desirable to combine according to the use atmosphere of a catalyst. For example, when used in an environment with a lot of moisture, a material other than an alkali metal may be selected. In addition, it is desirable to avoid combinations that form unstable complex oxides because they degrade catalyst performance.
In the second invention, the form of the metal compound is an intermetallic compound or a solid solution. The ratio (composition ratio) of the combination of the catalytically active species and the metal element M differs depending on whether or not the catalytically active species and the metal element M are completely dissolved. In the case where it is completely dissolved, it may be optional. When the solid solution is not completely dissolved, the composition ratio for forming the intermetallic compound is set or the solid solution limit is satisfied. In the intermetallic compound and the solid solution, Au, Pt, Pd, Rh, Ag, Ir, Ru, and Os, which are catalytically active species, are uniformly present at the atomic level, so that particles precipitated by heat treatment are finely and uniformly dispersed. On the other hand, in compounds having a composition ratio other than intermetallic compounds and solid solutions, Au, Pt, Pd, Rh, Ag, Ir, Ru, and Os are unevenly present in the compound, so that particles precipitated by heat treatment are coarse and non-uniform. Uniform dispersion and no catalytic activity.
[0011]
In addition to the above elements, an element that precipitates as fine particles during heat treatment and exhibits catalytic activity can be used as a catalytically active species. In addition, an element forming an oxide can be used as the metal element M.
Au is desirable as a catalytically active species because it has a low affinity with oxygen and does not form a complex oxide with an oxide or metal element M.
In the third invention of the present invention, when the amount of Au, Pt, Pd, Rh, Ag, Ir, Ru, Os in the metal compound is a predetermined loading amount, the metal compound may be heat-treated alone. On the other hand, when the amount is not a predetermined amount, heat treatment is performed by mixing a salt of the metal element M contained in the metal compound. The kind of salt should just become an oxide by heat processing.
[0012]
The metal element M of the present invention is preferably an alkaline earth metal, a lanthanoid, or a transition metal that easily generates an oxide from the catalytically active species Au, Pt, Pd, Rh, Ag, Ir, Ru, and Os. The reaction promoted by the alkaline earth metal oxide as a catalyst is initiated by separating H + from the molecular state, and the lanthanoid complex oxide is NO in the perovskite structure. Reduction and oxidation reactions are also carried out, and the activity is particularly high in oxidation reactions.
A method for producing the metal fine particle supported oxide catalyst of the present invention will be described.
The metal compound may be a conventional casting method such as high-frequency melting or arc melting. When an element that easily forms an oxide is included, it is desirable to melt and cast in a vacuum or an inert atmosphere. The shape of the ingot may be ingot or powder. However, in the case of an ingot, it is pulverized before heat treatment.
[0013]
Although there is no restriction | limiting in the heat processing temperature and time of this invention, in order to suppress the growth of the depositing metal microparticle, temperature 500-1200 degreeC and time 5-100 hr are desirable.
This heat treatment is performed in an atmosphere containing oxygen. By this heat treatment, the metal element M becomes an oxide. Au, Pt, Pd, Rh, Ag, Ir, Ru, and Os that do not become oxides diffuse in the oxide to form fine particles. The fine particles formed in this manner are firmly bonded to the oxide and uniformly dispersed. It is considered that the interaction between the fine particles and the oxide is strongly bonded and the catalytic activity is improved.
As another form of use of the present invention, when the above metal compound is welded to a structure such as a monolith at an atomic level and heat treatment is performed in an atmosphere containing oxygen, the metal element M in the metal compound as the coating layer is an oxide. It becomes. Au, Pt, Pd, Rh, Ag, Ir, Ru, and Os that do not become oxides diffuse in the oxide to form fine particles. The coating layer of the metal particle-supported oxide catalyst formed in this way is hard to peel off because it is firmly bonded to the surface of a structure such as a monolith.
[0014]
At this time, if PVD (plasma vapor deposition) or CVD (chemical vapor deposition) is used for the welding, the catalyst layer can be coated even on a structure that cannot be supported by the conventional method using slurry. The welding may be performed not only on the structure but also on a powder of Al 2 O 3 or the like.
Hereinafter, the present invention will be described in more detail based on examples.
[0015]
【Example】
Example 1
AuSr intermetallic compound (Au: Sr molar ratio 1: 1) was melt cast using high frequency melting in an argon gas atmosphere. After pulverizing the AuSr intermetallic compound, a mixture of AuSr intermetallic compound: 25 g and Sr (OH) 2 .8H 2 O: 28 g was heat-treated in the atmosphere at 650 ° C. for 120 hours. Γ-Al 2 O 3 powder was mixed with Au / SrO powder with an Au particle diameter of 34 nm obtained by heat treatment to obtain Au / SrO / Al 2 O 3 catalyst A with an Au amount of 0.5 wt%. XRD (X-ray diffraction) was used for the particle size and qualitative analysis, and fluorescent X-ray analysis was used for the composition analysis.
[0016]
Example 2
A La 2 Au intermetallic compound (Au: La molar ratio 1: 2) was melt-cast using high-frequency melting in an argon gas atmosphere. After grinding the La 2 Au intermetallic compound, the La 2 Au intermetallic compound, a heat treatment was carried out 750 ° C. × 30 hours in air. Γ-Al 2 O 3 powder was mixed with Au / La 2 O 3 powder with an Au particle diameter of 54 nm obtained by heat treatment to obtain Au / La 2 O 3 / Al 2 O 3 catalyst B with an Au amount of 2 wt%. . XRD (X-ray diffraction) was used for the particle size and qualitative analysis, and fluorescent X-ray analysis was used for the composition analysis.
[0017]
Comparative Example 1
Γ-Al 2 O 3 powder was added to a HAuCl 4 aqueous solution (5 × 10 −3 mol / l), stirred for 3 hours, and then dried at 120 ° C. for 24 hours in the atmosphere. After drying, heat treatment was performed at 500 ° C. for 2 hours in the air to obtain an Au / Al 2 O 3 catalyst C having an Au particle diameter of 42 nm and an Au amount of 2 wt%. The particle size and qualitative analysis were performed using XRD (X-ray diffraction), and the composition analysis was performed using fluorescent X-ray analysis.
Next, the purification rates of the catalysts A and B obtained in Examples 1 and 2 and the catalyst C obtained in Comparative Example 1 were measured using an atmospheric pressure flow reactor. The purification rate measurement gas at this time was the gas composition shown in Table 1, No. 1 was the lean composition, No. 2 was the stoichiometric equivalent composition, and the catalytic activity was evaluated at a gas space velocity of 150,000 h- 1 .
[0018]
[Table 1]
Each catalyst bed temperature was raised to 500 ° C., and the temperature was decreased stepwise to 400 ° C., 300 ° C., and 200 ° C., and the purification rate in a steady state was measured at each temperature. The definition of the purification rate at this time is as follows.
Purification rate = [(input gas concentration−output gas concentration) / input gas concentration] × 100
The measurement results are shown in Table 2.
[0020]
[Table 2]
From this result, the Nos. 1 to 4 of the present invention are superior in the purification rate for CO and HC at all measured temperatures and in the maximum purification rate of NO as compared with Nos. 5 and 6 of the comparative examples. It can be seen that the catalyst activity is high.
[0022]
【The invention's effect】
According to the present invention, the metal particles deposited on the surface are firmly bonded to the carrier and are excellent in heat resistance as a catalyst. Further, the yield / support efficiency of the catalyst metal is improved as compared with the case where the catalyst is produced using the solution. Furthermore, since the manufacturing method is simple, the cost is low, and handling during work is easy.
Claims (2)
Ｍ：Ｓｒ，Ｎｂ，Ｌｉ，Ｌａ，Ａｌ，Ｓｉ，Ｍｇ，Ｃａ，Ｂａ，Ｃｅ，Ｎｄ，Ｔｉ，Ｆｅ，Ｃｏ，Ｎｉ，Ｃｕ，Ｚｎ，Ｚｒ，Ｖ，Ｔａ，Ｃｒ，Ｍｏ，Ｗ，Ｎａ，Ｋ，Ｂｅ，Ｓｃ，Ｙ，Ｉｎ，Ｓｎ，Ｐｂ，Ｂｉ． It is composed of one or more elements selected from Au, Pt, Pd, Rh, Ag, Ir, Ru, Os and one or more elements selected from the metal M shown below . An exhaust gas purifying catalyst comprising a metal fine particle-supported oxide, wherein the catalyst is produced by heat-treating a solid solution composed only of an intermetallic compound or a metal in an atmosphere containing oxygen.
M: Sr, Nb, Li, La, Al, Si, Mg, Ca, Ba, Ce, Nd, Ti, Fe, Co, Ni, Cu, Zn, Zr, V, Ta, Cr, Mo, W, Na, K, Be, Sc, Y, In, Sn, Pb, Bi.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP02541197A JP3777696B2 (en) | 1997-02-07 | 1997-02-07 | Metal fine particle supported oxide catalyst |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP02541197A JP3777696B2 (en) | 1997-02-07 | 1997-02-07 | Metal fine particle supported oxide catalyst |
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| Publication Number | Publication Date |
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| JPH10216519A JPH10216519A (en) | 1998-08-18 |
| JP3777696B2 true JP3777696B2 (en) | 2006-05-24 |
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| JP02541197A Expired - Lifetime JP3777696B2 (en) | 1997-02-07 | 1997-02-07 | Metal fine particle supported oxide catalyst |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8501662B2 (en) | 2007-03-20 | 2013-08-06 | Denso Corporation | Catalyst material |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6440378B1 (en) | 1997-12-22 | 2002-08-27 | Toyota Jidosha Kabushiki Kaisha | Catalyst for purifying exhaust gases, a method of producing the same, and a method of purifying exhaust gases |
| DE19964073A1 (en) * | 1999-12-31 | 2001-07-26 | Dieter Seipler | Exhaust gas purification catalyst and process for its manufacture |
| JP4590733B2 (en) * | 2000-02-22 | 2010-12-01 | マツダ株式会社 | Exhaust gas purification catalyst and exhaust gas purification method using the catalyst |
| US7150861B2 (en) | 2001-09-28 | 2006-12-19 | Nippon Shokubai Co., Ltd. | Catalyst for purification of exhaust gases and process for purification of exhaust gases |
| JP2005329318A (en) * | 2004-05-19 | 2005-12-02 | Mazda Motor Corp | Diesel particulate filter |
| JP4589032B2 (en) * | 2004-05-28 | 2010-12-01 | 戸田工業株式会社 | Exhaust gas purification catalyst and oxygen storage material for the catalyst |
| JP4883162B2 (en) | 2009-10-02 | 2012-02-22 | トヨタ自動車株式会社 | Exhaust gas purification catalyst for CO or HC purification |
| US9079167B2 (en) | 2011-02-07 | 2015-07-14 | Toyota Jidosha Kabushiki Kaisha | NOx purification catalyst |
| JP5795083B2 (en) | 2011-02-07 | 2015-10-14 | トヨタ自動車株式会社 | NOx purification catalyst |
| CN103370122B (en) | 2011-02-07 | 2016-05-04 | 丰田自动车株式会社 | NOXCleaning catalyst |
| EP2714246B1 (en) | 2011-05-24 | 2014-12-31 | Toyota Jidosha Kabushiki Kaisha | Exhaust purification system |
| US9492814B2 (en) | 2013-04-08 | 2016-11-15 | Saudi Basic Industries Corporation | Catalyst for conversion of propylene to product comprising a carboxylic acid moiety |
| CN105032410B (en) * | 2015-06-03 | 2017-08-11 | 中国科学院生态环境研究中心 | A kind of Ag/Al2O3Catalyst, preparation method and its usage |
| KR102051857B1 (en) * | 2017-09-29 | 2019-12-04 | 한국화학연구원 | High performance nitrogen oxide reduction catalyst and method for producing the same |
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1997
- 1997-02-07 JP JP02541197A patent/JP3777696B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8501662B2 (en) | 2007-03-20 | 2013-08-06 | Denso Corporation | Catalyst material |
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| JPH10216519A (en) | 1998-08-18 |
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