JP2001205087A - Catalyst for cleaning exhaust gas - Google Patents
Catalyst for cleaning exhaust gasInfo
- Publication number
- JP2001205087A JP2001205087A JP2000018016A JP2000018016A JP2001205087A JP 2001205087 A JP2001205087 A JP 2001205087A JP 2000018016 A JP2000018016 A JP 2000018016A JP 2000018016 A JP2000018016 A JP 2000018016A JP 2001205087 A JP2001205087 A JP 2001205087A
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- Prior art keywords
- catalyst
- gold
- particles
- mass
- composite metal
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、排気ガス浄化用触
媒に関し、より詳しくは、リーン雰囲気下において優れ
たＮＯX 浄化性能を有し、かつ耐硫黄被毒性にも優れる
排気ガス浄化用触媒に関する。BACKGROUND OF THE INVENTION The present invention relates to an exhaust gas purifying catalyst, and more particularly, has excellent NO X purification performance in lean atmosphere, and relates to an exhaust gas purification catalyst excellent in resistance to sulfur poisoning .
【０００２】[0002]
【従来の技術】近年、地球保護の観点より、排気規制と
燃費規制が世界的に年々強化されつつある。燃費の向上
策としては、リーン条件下で燃料を燃焼させるリーンバ
ーンエンジンが有効であることが見出されている。とこ
ろが、このようなリーンバーンエンジンから排出された
排気ガスは、Ｏ2とＮＯX を比較的多量に含むため、従
来の三元触媒等ではＮＯX の浄化性能が不足するという
問題がある。2. Description of the Related Art In recent years, from the viewpoint of protection of the earth, emission regulations and fuel consumption regulations have been strengthened worldwide every year. As a measure for improving fuel efficiency, it has been found that a lean burn engine that burns fuel under lean conditions is effective. However, since the exhaust gas discharged from such a lean burn engine contains a relatively large amount of O 2 and NO X , there is a problem that the conventional three-way catalyst or the like lacks NO X purification performance.
【０００３】この問題を解決するため、本発明者らは、
合金化により触媒活性を高めるといった着想に基づき、
特開平１０−２１６５１８号公報において合金触媒を提
案している。さらに、かかる合金触媒を一層改良した触
媒として、リーン条件下での金属粒子上の吸着酸素量を
減らすことでＮＯX 浄化性能を向上させるといった着想
に基づき、特開平１１−１５６１９３号公報において、
触媒金属粒子の上に別な金属粒子の相を積相させた触媒
を提案している。In order to solve this problem, the present inventors have
Based on the idea of increasing the catalytic activity by alloying,
JP-A-10-216518 proposes an alloy catalyst. Further, as a catalyst to further improve such an alloy catalyst, based on the idea such improve NO X purification performance by reducing the adsorbed oxygen amount on the metal particles in the lean conditions, in JP-A-11-156193, JP-
A catalyst has been proposed in which a phase of another metal particle is accumulated on the catalyst metal particle.
【０００４】この積相構造を有する触媒によれば、触媒
金属粒子と金属相の電子状態の違いから、触媒金属粒子
と金属相の表面の電子状態が変化してＮＯX 浄化性能が
向上することが見出されている。ここで、「積相」と
は、１つの金属粒子の一部の表面が、１つ以上の別な金
属粒子によって被覆され、それらの接合領域を介してそ
れぞれの金属の相が存在する状態を言う。[0004] According to the catalyst having the product phase structure, the electronic state of the catalytic metal particles and the metal phase difference, to improve the NO X purification performance electronic state of the surface of the catalytic metal particles and the metal phase is changed Are found. Here, the “accumulated phase” refers to a state in which a part of the surface of one metal particle is covered with one or more other metal particles, and each metal phase exists through a joint region between them. To tell.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、かかる
積相構造を有する触媒は、排気ガス中に硫黄成分が含ま
れているとＮＯX 浄化性能が経時的に低下するという、
硫黄被毒の問題を生じやすいことが判明した。従って、
本発明は、リーン雰囲気下において優れたＮＯX 浄化性
能を有し、かつ耐硫黄被毒性にも優れた排気ガス浄化用
触媒を提供することを目的とする。[SUMMARY OF THE INVENTION However, the catalyst having such a product phase structure and contains sulfur components NO X purification performance that decreases with time in the exhaust gas,
It turned out to be prone to sulfur poisoning problems. Therefore,
The present invention has an excellent NO X purification performance in lean atmosphere, and an object of the invention to provide an exhaust gas purifying catalyst excellent in resistance to sulfur poisoning.
【０００６】[0006]
【課題を解決するための手段】上記目的は、無機酸化物
担体上に、白金、及びパラジウム又はロジウムを含む複
合金属粒子が担持され、前記複合金属粒子の上に金粒子
が積相されたことを特徴とする排気ガス浄化用触媒によ
って達成される。本発明における「複合金属粒子」と
は、白金と、パラジウム又はロジウム（以下「第２金
属」と称する。）の少なくとも一方を、白金／第２金属
のモル比が１００／１〜１／１の範囲で含み、粒子サイ
ズが全体として２０ナノメートル以下（ｎｍ）であり、
その粒子の中で白金元素と第２金属元素がそれぞれまと
まって存在する状態の金属粒子を言う。The object of the present invention is to provide a composite metal particle containing platinum, palladium or rhodium supported on an inorganic oxide carrier, and gold particles deposited on the composite metal particle. This is achieved by an exhaust gas purifying catalyst characterized by the following. The “composite metal particles” in the present invention refers to platinum and at least one of palladium and rhodium (hereinafter referred to as “second metal”) having a platinum / second metal molar ratio of 100/1 to 1/1. The particle size is less than or equal to 20 nanometers (nm) overall;
A metal particle in a state where a platinum element and a second metal element are present together in the particle.
【０００７】このような複合金属粒子の上に金粒子が積
相された構成の触媒では、耐硫黄被毒性が顕著に向上す
ることが見出されており、この理由は、金は硫黄と反応
しやすい性質を有するが、パラジウムもしくはロジウム
がこの金と硫黄の反応を抑えるためと考えられる。It has been found that sulfur poisoning resistance is remarkably improved in a catalyst having a structure in which gold particles are stacked on such composite metal particles, because gold reacts with sulfur. It is considered that palladium or rhodium suppresses the reaction between gold and sulfur.
【０００８】[0008]
【発明の実施の形態】本発明の触媒担体を構成する無機
酸化物は、限定されるものではないが、アルミナ、シリ
カ、ジルコニア、シリカ−アルミナ、ゼオライト、セリ
ア、又はこれらの混合物からなるものが挙げられる。BEST MODE FOR CARRYING OUT THE INVENTION The inorganic oxide constituting the catalyst carrier of the present invention is not limited, but may be alumina, silica, zirconia, silica-alumina, zeolite, ceria, or a mixture thereof. No.
【０００９】本発明において、この無機酸化物の上に白
金、及びパラジウム又はロジウム（第２金属）を含む複
合金属粒子が担持される。好ましくは、複合金属粒子中
の白金／第２金属のモル比は、３０／１〜２／１、より
好ましくは１５／１〜２／１であり、粒子径は、好まし
くは２〜１０ｎｍである。かかる範囲のものがＮＯX 浄
化性能と耐硫黄被毒性に優れるためである。In the present invention, composite metal particles containing platinum and palladium or rhodium (second metal) are supported on the inorganic oxide. Preferably, the molar ratio of platinum / second metal in the composite metal particles is 30/1 to 2/1, more preferably 15/1 to 2/1, and the particle diameter is preferably 2 to 10 nm. . Those of such a range is because it is excellent in the NO X purification performance and resistance to sulfur poisoning.
【００１０】好ましくは、第２金属は、複合金属粒子の
中で集合して存在し、１つの複合金属粒子の中で、５〜
５０個、より好ましくは１０〜３０個の金属元素の集合
として存在し、白金元素が「海」で第２金属元素が
「島」の、いわゆる「海島構造」を呈する。また、第２
金属の「島」の一部は露出する。かかる露出面が金と硫
黄の反応を抑えると考えられる。[0010] Preferably, the second metal is present as a group in the composite metal particle, and in one composite metal particle, 5 to 5
It exists as a set of 50, more preferably 10 to 30, metal elements, and exhibits a so-called "sea-island structure" in which the platinum element is "sea" and the second metal element is "islands". Also, the second
Part of the metal "island" is exposed. It is believed that such exposed surfaces suppress the reaction between gold and sulfur.
【００１１】無機酸化物の上に複合金属粒子を担持させ
るには、例えば、複合金属粒子が水等の媒体に分散した
コロイドに無機酸化物を浸し、次いでこの媒体を乾燥等
によって除去し、必要により大気中で３００〜６００℃
で加熱することによって行うことができる。In order to support the composite metal particles on the inorganic oxide, for example, the inorganic oxide is immersed in a colloid in which the composite metal particles are dispersed in a medium such as water, and then the medium is removed by drying or the like. 300-600 ° C in air due to
By heating.
【００１２】本発明において、この複合金属粒子の上に
金粒子が積相される。積相を形成するには、金属粒子上
に金粒子を堆積させることができる任意の方法から選択
された、例えば、沈殿法、吸着法、イオン交換法、還元
析出法等によって担持することができる。好ましくは、
金粒子は還元析出法、即ち、溶液中で金イオンを生成す
る金塩の水溶液に還元剤を添加し、金イオンを還元する
ことによって不溶性にし、金粒子を析出させる方法によ
って行う。かかる還元析出法においては、複合金属粒子
の上に、それより小さい粒径の金粒子を析出させること
が比較的容易である。In the present invention, gold particles are accumulated on the composite metal particles. To form the accumulated phase, it can be supported by any method capable of depositing gold particles on metal particles, for example, a precipitation method, an adsorption method, an ion exchange method, a reduction precipitation method, or the like. . Preferably,
The gold particles are formed by a reductive precipitation method, that is, a method in which a reducing agent is added to an aqueous solution of a gold salt that generates gold ions in a solution to make the gold ions insoluble by reducing the gold ions and deposit the gold particles. In such a reduction precipitation method, it is relatively easy to deposit gold particles having a smaller particle size on the composite metal particles.
【００１３】具体的には、例えば、金塩として、ＨＡｕ
Ｃｌ4 ・４Ｈ2 Ｏ、ＡｕＣｌ3 、ＡｕＣＮ、ＡｕＯＨ等
を用い、還元剤として、チオ硫酸ナトリウム、チオ硫酸
カリウム、メタ重亜硫酸ナトリウム、メタ重亜硫酸カリ
ウム、メタ重亜硫酸アンモニウム等を用い、上記の複合
金属粒子を担持した無機酸化物担体を浸した水に、これ
らの金塩及び還元剤を添加し、好ましくは、穏やかな攪
拌下に置くことによって金粒子を析出させる。好ましく
は、複合金属粒子中の白金と積相された金は、白金／金
のモル比で５０／１〜１／１、より好ましくは１５／１
〜５／１である。Specifically, for example, as a gold salt, HAu
Using Cl 4 · 4H 2 O, AuCl 3, AuCN, AuOH etc., as a reducing agent, sodium thiosulfate, potassium thiosulfate, using sodium metabisulfite, potassium metabisulfite, and ammonium metabisulfite, etc., said composite The gold salt and the reducing agent are added to water impregnated with the inorganic oxide carrier supporting the metal particles, and the gold particles are precipitated preferably by gentle stirring. Preferably, the gold phased with platinum in the composite metal particles is in a platinum / gold molar ratio of 50/1 to 1/1, more preferably 15/1.
５5/1.
【００１４】このようにして得られた担体上に金属粒子
を備えた触媒は、一般的なモノリス型触媒として使用す
る場合、モノリス基材上にその触媒を堆積させること
で、実際の触媒として使用することができる。[0014] When a catalyst obtained by providing metal particles on a support thus obtained is used as a general monolith type catalyst, the catalyst is deposited on a monolith substrate to be used as an actual catalyst. can do.
【００１５】なお、本発明の無機酸化物担体上に複合金
属粒子が担持され、その上に金粒子が積相された状態
は、例えば、分析透過型電子顕微鏡（ＴＥＭ）によって
観察することができる。高性能ＴＥＭを用いると、複合
金属粒子と金粒子の全体的な形態が観察できると同時
に、電子線ビームを小さくは１ｎｍの直径（数個の金属
元素の大きさに相当）まで細く絞って試料に照射するこ
とができ、そして、その照射された部位から放射される
元素に固有なＸ線を半導体検出器（ＥＤＸ）によって分
光分析することで、その照射部位に存在する元素を同定
することができる。したがって、全体的な形態観察と併
せて、電子線ビームを走査しながら元素を同定すること
により、元素の集合の大きさを把握することができる。The state in which the composite metal particles are supported on the inorganic oxide carrier of the present invention and the gold particles are stacked thereon can be observed, for example, by an analytical transmission electron microscope (TEM). . Using a high-performance TEM, the overall morphology of the composite metal particles and the gold particles can be observed, and at the same time, the electron beam is narrowed down to a diameter of 1 nm (corresponding to the size of several metal elements). The X-rays specific to the element emitted from the irradiated site can be subjected to spectroscopic analysis by a semiconductor detector (EDX) to identify the element present at the irradiated site. it can. Therefore, by identifying the element while scanning the electron beam together with the overall morphological observation, it is possible to grasp the size of the set of elements.
【００１６】このようにして分析した、本発明の排気ガ
ス浄化用触媒を構成する複合金属粒子と金粒子の全体的
な形態と個々の粒子のサイズをモデル的に示したのが図
１である。即ち、図１はあくまでモデル的に示したもの
であるが、担体１上の白金粒子２の中に、白金粒子より
小さいサイズのパラジウム又はロジウムの第２金属３が
分散されて複合金属粒子が形成され、その複合金属粒子
の白金又は第２金属の表面上に金粒子４が存在している
状態を示す。下記の実施例１〜３で得られた触媒を、上
記のような電子線ビームを走査しながら元素を同定する
ＴＥＭ分析に供したところ、いずれも図１のような「海
島構造」の状態であると判断される分析結果が得られて
いる。FIG. 1 is a model diagram showing the overall morphology of the composite metal particles and the gold particles constituting the exhaust gas purifying catalyst of the present invention and the sizes of the individual particles analyzed in this manner. . That is, although FIG. 1 is only a model diagram, a composite metal particle is formed by dispersing a second metal 3 of palladium or rhodium smaller in size than platinum particles in platinum particles 2 on a carrier 1. This shows a state where the gold particles 4 exist on the surface of the platinum or the second metal of the composite metal particles. When the catalysts obtained in the following Examples 1 to 3 were subjected to TEM analysis for identifying elements while scanning with the above-mentioned electron beam, all of the catalysts were in a “sea-island structure” as shown in FIG. Analytical results determined to be present have been obtained.
【００１７】[0017]
【実施例】実施例１ 複合金属粒子Ｉを１．０６×１０-1質量％分散させたコ
ロイド（（株）田中貴金属製）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。乾燥の後、大気中で４００℃×１２
時間の熱処理を行い、１．９５質量％（Ｐｔ−Ｐｄ）／
Ａｌ2 Ｏ3 粉末を得た。ここで、複合金属粒子Ｉは、白
金とパラジウムをＰｔ／Ｐｄ＝９／１のモル比で含み、
ＴＥＭ分析により、複合金属粒子Ｉの粒子径は全体とし
て２〜４ｎｍで、その中に約１ｎｍのサイズのパラジウ
ム粒子が、複合金属粒子Ｉの一部の表面を形成して散在
する状態を有することが把握された。EXAMPLE 1 γ-Al 2 O 3 powder was added to a colloid (manufactured by Tanaka Kikinzoku Co., Ltd.) in which composite metal particles I were dispersed at 1.06 × 10 -1 mass%, and the mixture was stirred for 3 hours. Then, drying was performed at 120 ° C. for 24 hours in the air. After drying, 400 ° C x 12 in air
Heat treatment for 1.95% by mass (Pt-Pd) /
An Al 2 O 3 powder was obtained. Here, the composite metal particle I contains platinum and palladium in a molar ratio of Pt / Pd = 9/1,
According to TEM analysis, the particle diameter of the composite metal particles I is 2 to 4 nm as a whole, and the palladium particles having a size of about 1 nm form a part of the surface of the composite metal particles I and are scattered. Was grasped.
【００１８】この１．９５質量％（Ｐｔ−Ｐｄ）／Ａｌ
2 Ｏ3 粉末を５．５７質量％分散させた６０℃のイオン
交換水に、ＨＡｕＣｌ4 ・４Ｈ2 Ｏ（２．３３×１０-2
質量％）、Ｎａ2 Ｓ2 Ｏ3 ・５Ｈ2 Ｏ（１．１２×１０
-2質量％）、Ｎａ2 ＳＯ3 （２．８５×１０-1質量
％）、Ｃ6 Ｈ7 ＮａＯ6 （１．１２質量％）を添加し、
２４時間攪拌しながらＡｕを還元析出させた。This 1.95 mass% (Pt-Pd) / Al
The 2 O 3 powder in 60 ° C. of deionized water was dispersed 5.57 wt%, HAuCl 4 · 4H 2 O (2.33 × 10 -2
Mass%), Na 2 S 2 O 3 .5H 2 O (1.12 × 10
-2 % by mass), Na 2 SO 3 (2.85 × 10 -1 % by mass) and C 6 H 7 NaO 6 (1.12% by mass),
Au was reduced and precipitated while stirring for 24 hours.
【００１９】この還元析出後、ろ過、洗浄し、大気中で
１２０℃×２時間の乾燥を行った。乾燥の後、大気中で
５００℃×２時間の熱処理を行い、γ−Ａｌ2 Ｏ3 に担
持された、Ｐｔ／Ｐｄ／Ａｕのモル比がＰｔ／Ｐｄ／Ａ
ｕ＝９／１／１、ＰｔとＰｄとＡｕの合計量が２．０質
量％の（Ｐｔ−Ｐｄ−Ａｕ）／Ａｌ2 Ｏ3 触媒Ａを得
た。After this reduction precipitation, the precipitate was filtered, washed, and dried at 120 ° C. for 2 hours in the air. After drying, heat treatment was performed at 500 ° C. for 2 hours in the air, and the molar ratio of Pt / Pd / Au supported on γ-Al 2 O 3 was Pt / Pd / A.
u = 9/1/1, to give a total amount of Pt and Pd and Au of 2.0 wt% of (Pt-Pd-Au) / Al 2 O 3 catalyst A.
【００２０】実施例２ 複合金属粒子Ｉを分散させたコロイドの代わりに、複合
金属粒子IIを分散させたコロイド（（株）田中貴金属
製）を用いた以外は実施例１と同様にして、Ｐｔ／Ｐｄ
／Ａｕ＝７／３／３、ＰｔとＰｄとＡｕの合計量が２．
０質量％の（Ｐｔ−Ｐｄ−Ａｕ）／Ａｌ2 Ｏ3 触媒Ｂを
得た。ここで、複合金属粒子IIは、白金とパラジウムを
Ｐｔ／Ｐｄ＝７／３のモル比で含み、ＴＥＭ分析によ
り、複合金属粒子IIの粒子径は全体として３〜５ｎｍ
で、その中に約１ｎｍのサイズのパラジウム粒子が、複
合金属粒子IIの一部の表面を形成して散在する状態を有
することが把握された。Example 2 Pt was prepared in the same manner as in Example 1 except that a colloid in which composite metal particles II were dispersed (manufactured by Tanaka Kikinzoku Co., Ltd.) was used instead of the colloid in which composite metal particles I were dispersed. / Pd
/ Au = 7/3/3, and the total amount of Pt, Pd and Au is 2.
0 wt% to obtain a (Pt-Pd-Au) / Al 2 O 3 catalyst B. Here, the composite metal particles II contain platinum and palladium in a molar ratio of Pt / Pd = 7/3, and the total particle diameter of the composite metal particles II is 3 to 5 nm by TEM analysis.
Therefore, it was found that palladium particles having a size of about 1 nm formed a part of the surface of the composite metal particles II and were scattered therein.
【００２１】実施例３ 複合金属粒子Ｉを分散させたコロイドの代わりに、複合
金属粒子III を分散させたコロイド（（株）田中貴金属
製）を用いた以外は実施例１と同様にして、Ｐｔ／Ｒｈ
／Ａｕ＝９／１／１、ＰｔとＲｈとＡｕの合計量が２．
０質量％の（Ｐｔ−Ｒｈ−Ａｕ）／Ａｌ2 Ｏ3 触媒Ｃを
得た。ここで、複合金属粒子III は、白金とロジウムを
Ｐｔ／Ｒｈ＝９／１のモル比で含み、ＴＥＭ分析によ
り、複合金属粒子III の粒子径は全体として２〜４ｎｍ
で、その中に約１ｎｍのサイズのロジウム粒子が、複合
金属粒子III の一部の表面を形成して散在する状態を有
することが把握された。Example 3 Pt was prepared in the same manner as in Example 1 except that a colloid (commercially available from Tanaka Kikinzoku Co., Ltd.) in which composite metal particles III were dispersed was used instead of the colloid in which composite metal particles I were dispersed. / Rh
/ Au = 9/1/1, and the total amount of Pt, Rh and Au is 2.
0 wt% was obtained (Pt-Rh-Au) / Al 2 O 3 catalyst C. Here, the composite metal particles III contain platinum and rhodium in a molar ratio of Pt / Rh = 9/1, and the total particle diameter of the composite metal particles III is 2 to 4 nm by TEM analysis.
It was found that rhodium particles having a size of about 1 nm formed a part of the surface of the composite metal particles III and were scattered therein.
【００２２】比較例１ Ｐｔ（ＮＯ2 ）2 （ＮＨ3 ）2 を９．９８×１０-2質量
％溶解した水溶液に、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。乾燥の後、大気中で３００℃×２時間の加熱を
行い、１．８０質量％Ｐｔ／Ａｌ2 Ｏ3 粉末を得た。こ
の１．８０質量％Ｐｔ／Ａｌ2 Ｏ3 粉末を４．６９質量
％分散させた６０℃のイオン交換水に、ＨＡｕＣｌ4 ・
４Ｈ2 Ｏ（２．０４×１０-2質量％）、Ｎａ 2 Ｓ2 Ｏ3
・５Ｈ2 Ｏ（９．４０×１０-2質量％）、Ｎａ2 ＳＯ3
（２．４１×１０-1質量％）、Ｃ6 Ｈ7 ＮａＯ6 （９．
４５×１０-1質量％）を添加し、２４時間攪拌しながら
Ａｕを還元析出させた。Comparative Example 1 Pt (NOTwo)Two(NHThree)Two9.98 × 10-2mass
% Dissolved aqueous solution, γ-AlTwoOThreeAdd powder and add 3
After stirring for 120 hours, dry in air at 120 ° C for 24 hours.
went. After drying, heat in air at 300 ℃ for 2 hours.
1.80 mass% Pt / AlTwoOThreeA powder was obtained. This
1.80 mass% Pt / AlTwoOThree4.69 mass of powder
% Dispersed in 60 ° C. ion-exchanged water.Four・
4HTwoO (2.04 × 10-2Mass%), Na TwoSTwoOThree
・ 5HTwoO (9.40 × 10-2Mass%), NaTwoSOThree
(2.41 × 10-1Mass%), C6H7NaO6(9.
45 × 10-1% By mass) and stirring for 24 hours.
Au was precipitated by reduction.
【００２３】この還元析出の後、ろ過、洗浄し、大気中
で１２０℃×２時間の乾燥を行った。乾燥の後、大気中
で５００℃×２時間の熱処理を行い、Ｐｔ／Ａｕのモル
比がＰｔ／Ａｕ＝９／１、ＰｔとＡｕの合計量が２質量
％の（Ｐｔ−Ａｕ）／Ａｌ2Ｏ3 比較触媒Ｄを得た。After this reduction precipitation, filtration, washing and drying were performed at 120 ° C. for 2 hours in the air. After drying, heat treatment is performed at 500 ° C. for 2 hours in the air, and the Pt / Au molar ratio is Pt / Au = 9/1, and the total amount of Pt and Au is 2 mass% (Pt-Au) / Al 2 O 3 comparative catalyst D was obtained.
【００２４】比較例２ Ｐｔ（ＮＯ2 ）2 （ＮＨ3 ）2 を９．５７×１０-2質量
％溶解した水溶液に、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。乾燥の後、大気中で３００℃×２時間の加熱を
行い、１．７３質量％Ｐｔ／Ａｌ2 Ｏ3 粉末を得た。Comparative Example 2 γ-Al 2 O 3 powder was added to an aqueous solution in which 9.57 × 10 -2 mass% of Pt (NO 2 ) 2 (NH 3 ) 2 was dissolved.
After stirring for an hour, drying was performed at 120 ° C. for 24 hours in the air. After drying, heating was performed at 300 ° C. for 2 hours in the atmosphere to obtain 1.73 mass% Pt / Al 2 O 3 powder.
【００２５】この１．７３質量％Ｐｔ／Ａｌ2 Ｏ3 粉末
を５．５７質量％分散させた６０℃のイオン交換水に、
Ｐｄ（ＮＯ3 ）2 （１．２５×１０-2質量％）、Ｎａ2
ＳＯ 3 （２．７４×１０-1質量％）、Ｃ6 Ｈ7 ＮａＯ6
（１．０８質量％）を添加し、２４時間攪拌しながらＰ
ｄを還元析出させた。この還元析出の後、ろ過、洗浄
し、大気中で１２０℃×２時間の乾燥を行った。乾燥の
後、大気中で５００℃×２時間の熱処理を行い、Ｐｔ／
Ｐｄのモル比がＰｔ／Ｐｄ＝９／１、ＰｔとＰｄの合計
量が１．８３質量％の（Ｐｔ−Ｐｄ）／Ａｌ2 Ｏ3 粉末
を得た。This 1.73 mass% Pt / AlTwoOThreePowder
In 60 ° C. ion-exchanged water in which 5.57% by mass of
Pd (NOThree)Two(1.25 × 10-2Mass%), NaTwo
SO Three(2.74 × 10-1Mass%), C6H7NaO6
(1.08% by mass) and stirred for 24 hours.
d was precipitated by reduction. After this reduction precipitation, filtration and washing
Then, drying was performed at 120 ° C. for 2 hours in the air. Dry
Thereafter, a heat treatment at 500 ° C. for 2 hours is performed in the atmosphere, and Pt /
The molar ratio of Pd is Pt / Pd = 9/1, and the sum of Pt and Pd
(Pt-Pd) / Al with an amount of 1.83% by massTwoOThreePowder
I got
【００２６】この１．８３質量％（Ｐｔ−Ｐｄ）／Ａｌ
2 Ｏ3 粉末を５．５７質量％分散させた６０℃のイオン
交換水に、ＨＡｕＣｌ4 ・４Ｈ2 Ｏ（２．２３×１０-2
質量％）、Ｎａ2 Ｓ2 Ｏ3 ・５Ｈ2 Ｏ（１．０８×１０
-1質量％）、Ｎａ2 ＳＯ3 （２．７３×１０-1質量
％）、Ｃ6 Ｈ7 ＮａＯ6 （１．０７質量％）を添加し、
２４時間攪拌しながらＡｕを還元析出させた。This 1.83 mass% (Pt-Pd) / Al
The 2 O 3 powder in 60 ° C. of deionized water was dispersed 5.57 wt%, HAuCl 4 · 4H 2 O (2.23 × 10 -2
Mass%), Na 2 S 2 O 3 .5H 2 O (1.08 × 10
-1 % by mass), Na 2 SO 3 (2.73 × 10 -1 % by mass), C 6 H 7 NaO 6 (1.07% by mass),
Au was reduced and precipitated while stirring for 24 hours.
【００２７】この還元析出の後、ろ過、洗浄し、大気中
で１２０℃×２時間の乾燥を行った。乾燥の後、大気中
で５００℃×２時間の熱処理を行い、Ｐｔ／Ｐｄ／Ａｕ
のモル比がＰｔ／Ｐｄ／Ａｕ＝９／１／１、ＰｔとＰｄ
とＡｕの合計量が２．０質量％の（Ｐｔ−Ｐｄ−Ａｕ）
／Ａｌ2 Ｏ3 比較触媒Ｅを得た。After this reduction precipitation, the precipitate was filtered, washed, and dried at 120 ° C. for 2 hours in the air. After drying, heat treatment is performed in the air at 500 ° C. for 2 hours, and Pt / Pd / Au
Is Pt / Pd / Au = 9/1/1, and Pt and Pd
(Pt-Pd-Au) having a total amount of 2.0% by mass of Au and Au
/ Al 2 O 3 comparative catalyst E was obtained.
【００２８】比較例３ Ｐｔ（ＮＯ2 ）2 （ＮＨ3 ）2 を９．５９×１０-2質量
％溶解した水溶液に、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。乾燥の後、大気中で３００℃×２時間の加熱を
行い、１．７３質量％Ｐｔ／Ａｌ2 Ｏ3 粉末を得た。Comparative Example 3 γ-Al 2 O 3 powder was added to an aqueous solution in which Pt (NO 2 ) 2 (NH 3 ) 2 was dissolved at 9.59 × 10 -2 mass%, and
After stirring for an hour, drying was performed at 120 ° C. for 24 hours in the air. After drying, heating was performed at 300 ° C. for 2 hours in the atmosphere to obtain 1.73 mass% Pt / Al 2 O 3 powder.
【００２９】この１．７３質量％Ｐｔ／Ａｌ2 Ｏ3 粉末
を５．５６質量％分散させた６０℃のイオン交換水に、
ＲｈＣｌ3 （１．１３×１０-2質量％）、Ｎａ2 Ｓ2 Ｏ
3 ・５Ｈ2 Ｏ（１．０７×１０-1質量％）、Ｎａ2 ＳＯ
3 （２．７３×１０-1質量％）、Ｃ6 Ｈ7 ＮａＯ
6 （１．０７質量％）を添加し、２４時間攪拌しながら
Ｒｈを還元析出させた。この還元析出の後、ろ過、洗浄
し、大気中で１２０℃×２時間の乾燥を行った。乾燥の
後、大気中で５００℃×２時間の熱処理を行い、Ｐｔ／
Ｒｈのモル比がＰｔ／Ｒｈ＝９／１、ＰｔとＲｈの合計
量が１．８３質量％の（Ｐｔ−Ｒｈ）／Ａｌ2 Ｏ3 粉末
を得た。This 1.73 mass% Pt / Al 2 O 3 powder was dispersed in 5.56 mass% ion-exchanged water at 60 ° C.
RhCl 3 (1.13 × 10 −2 mass%), Na 2 S 2 O
3 · 5H 2 O (1.07 × 10 -1 wt%), Na 2 SO
3 (2.73 × 10 -1 mass%), C 6 H 7 NaO
6 (1.07% by mass) was added, and Rh was reduced and precipitated while stirring for 24 hours. After this reductive precipitation, filtration, washing, and drying at 120 ° C. for 2 hours in the air were performed. After drying, a heat treatment at 500 ° C. for 2 hours is performed in the atmosphere, and Pt /
The molar ratio of Rh is the total amount of Pt / Rh = 9/1, Pt and Rh was obtained 1.83 wt% of (Pt-Rh) / Al 2 O 3 powder.
【００３０】次いで、比較例２と同様にして、（Ｐｔ−
Ｒｈ）／Ａｌ2 Ｏ3 粉末上にＡｕを還元析出させ、５０
０℃×２時間の熱処理を行ってＰｔ／Ｒｈ／Ａｕのモル
比がＰｔ／Ｒｈ／Ａｕ＝９／１／１、ＰｔとＲｈとＡｕ
の合計量が２．０質量％の（Ｐｔ−Ｒｈ−Ａｕ）／Ａｌ
2 Ｏ3 比較触媒Ｆを得た。Next, in the same manner as in Comparative Example 2, (Pt-
Rh) / precipitate Au on Al 2 O 3 powder,
A heat treatment at 0 ° C. × 2 hours is performed so that the molar ratio of Pt / Rh / Au is Pt / Rh / Au = 9/1/1, and Pt, Rh, and Au
(Pt-Rh-Au) / Al having a total amount of 2.0% by mass
2 O 3 comparative catalyst F was obtained.
【００３１】比較例４ 複合金属粒子IVを１．１７×１０-1質量％分散させたコ
ロイド（（株）田中貴金属製）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。乾燥の後、大気中で５００℃×２時
間の熱処理を行い、Ｐｔ／Ｐｄ／Ａｕのモル比がＰｔ／
Ｐｄ／Ａｕ＝９／１／１、ＰｔとＰｄとＡｕの合計量が
２．０質量％の（Ｐｔ−Ｐｄ−Ａｕ）／Ａｌ2 Ｏ3 触媒
Ｇを得た。ここで、複合金属粒子IVは、ＴＥＭ分析によ
り、複合金属粒子IVの粒子径は全体として２〜４ｎｍ
で、その中に約１ｎｍのサイズのパラジウム粒子と金粒
子が、複合金属粒子IVの一部の表面を形成して散在する
状態を有することが把握された。Comparative Example 4 γ-Al 2 O 3 powder was added to a colloid (manufactured by Tanaka Kikinzoku Co., Ltd.) in which composite metal particles IV were dispersed at 1.17 × 10 -1 mass%, and the mixture was stirred for 3 hours. Drying was performed at 120 ° C. for 24 hours in the air. After drying, heat treatment was performed at 500 ° C. for 2 hours in the air, and the molar ratio of Pt / Pd / Au was changed to Pt / Pt / Au.
The total amount of Pd / Au = 9/1/ 1, Pt , Pd and Au were obtained in 2.0% by weight (Pt-Pd-Au) / Al 2 O 3 catalyst G. Here, according to TEM analysis, the composite metal particles IV have a total particle diameter of 2 to 4 nm.
Thus, it was found that palladium particles and gold particles having a size of about 1 nm formed a part of the surface of the composite metal particles IV and were scattered therein.
【００３２】−硫黄被毒処理− 各触媒Ａ〜Ｇに、下記組成のガス雰囲気下で、６５０℃
×３時間の硫黄被毒処理を施した。 ガス組成：３００ｐｐｍＳＯ2 ＋１５０ｐｐｍＣＯ＋６
７０ｐｐｍＣ3 Ｈ6＋２５０ｐｐｍＮＯ＋１０％Ｏ2 ＋
６．５％ＣＯ2 ＋３％Ｈ2 Ｏ ガス空間速度：１０００００ｈ-1 -Sulfur poisoning treatment- Each of the catalysts A to G was subjected to 650 ° C. in a gas atmosphere having the following composition.
× 3 hours of sulfur poisoning treatment was performed. Gas composition: 300 ppm SO 2 +150 ppm CO + 6
70 ppm C 3 H 6 +250 ppm NO + 10% O 2 +
6.5% CO 2 + 3% H 2 O Gas space velocity: 100000h -1
【００３３】−排気ガス浄化性能の評価− 各触媒Ａ〜Ｇについて、上記の硫黄被毒処理の前後のＮ
ＯX 浄化性能を以下の条件で測定した。 ガス組成：１０００ｐｐｍＣＯ＋６６７ｐｐｍＣ3 Ｈ6
＋２５０ｐｐｍＮＯ＋７．３％Ｏ2 ＋６．７％ＣＯ2 ＋
５％Ｈ2 Ｏ （残余：Ｎ2 ） ガス空間速度：１５００００ｈ-1 １００℃から５００℃への昇温評価、昇温速度１０℃／
min 各触媒Ａ〜Ｇの浄化性能の測定値より、ＮＯX 浄化率を
下記の式によって求め、各触媒Ａ〜Ｇの結果を表１にま
とめて示した。 浄化率＝〔（入ガス濃度−出ガス濃度）÷入ガス濃度〕
×１００-Evaluation of exhaust gas purification performance- For each of the catalysts A to G, N
The O X purification performance was measured under the following conditions. Gas composition: 1000 ppm CO + 667 ppm C 3 H 6
+250 ppm NO + 7.3% O 2 + 6.7% CO 2 +
5% H 2 O (residual: N 2 ) Gas space velocity: 150,000 h −1 Evaluation of temperature rise from 100 ° C. to 500 ° C., temperature rise rate 10 ° C. /
min than the measured value of the purification performance of each catalyst A-G, the NO X purification rate calculated by the following equation, the results of each catalyst A-G shown in Table 1. Purification rate = [(input gas concentration-output gas concentration) / input gas concentration]
× 100
【００３４】[0034]
【表１】 [Table 1]
【００３５】−結果より− 本発明の触媒Ａ〜Ｃは、硫黄被毒処理に供した後もリー
ン雰囲気下において優れたＮＯX 浄化性能を有してい
る。これは、パラジウム又はロジウムによって硫黄と金
の反応の抑えられ、金粒子を積相した最適な触媒構造が
維持されたためと考えられる。これに対し、比較例の触
媒Ｄは、硫黄被毒処理に供した後にかなりのＮＯX 浄化
性能の低下を呈している。これは、白金粒子の上に金粒
子を積相した触媒であってパラジウム又はロジウムを含
まないため、金と硫黄との反応により、金粒子を積相し
た最適な触媒構造が破壊されたためと考えられる。[0035] - Results from - catalyst A~C of the present invention has an excellent NO X purification performance in lean atmosphere even after subjected to sulfur poisoning treatment. This is considered to be because the reaction between sulfur and gold was suppressed by palladium or rhodium, and an optimal catalyst structure in which gold particles were accumulated was maintained. On the other hand, the catalyst D of the comparative example exhibited a considerable decrease in NO X purification performance after being subjected to the sulfur poisoning treatment. This is thought to be due to the fact that because the catalyst is a catalyst in which gold particles are stacked on platinum particles and does not contain palladium or rhodium, the reaction between gold and sulfur destroys the optimal catalyst structure in which gold particles are stacked. Can be
【００３６】また、比較例の触媒Ｅ〜Ｆは、白金、パラ
ジウム又はロジウム、及び金を含むものの、パラジウム
又はロジウム粒子が白金粒子の表面上に堆積されて存在
し、白金粒子の中に埋設されていないため、触媒構造が
最適化されておらず、耐硫黄被毒性が低いものと考えら
れる。また、比較例の触媒Ｇは、白金、パラジウム、及
び金を含むものの、金粒子が白金粒子の中に埋設された
状態であって積相されていないため、触媒構造が最適化
されておらず、耐硫黄被毒性が低いものと考えられる。The catalysts EF of Comparative Examples contain platinum, palladium or rhodium, and gold, but palladium or rhodium particles are deposited on the surface of the platinum particles and embedded in the platinum particles. Therefore, it is considered that the catalyst structure was not optimized and the sulfur poisoning resistance was low. Further, although the catalyst G of the comparative example contains platinum, palladium, and gold, since the gold particles are embedded in the platinum particles and are not stacked, the catalyst structure is not optimized. It is considered that sulfur poisoning resistance is low.
【００３７】[0037]
【発明の効果】リーン雰囲気下において優れたＮＯX 浄
化性能を有し、かつ耐硫黄被毒性にも優れた排気ガス浄
化用触媒を提供することができる。Effects of the Invention has an excellent NO X purification performance in lean atmosphere, and it is possible to provide an exhaust gas purifying catalyst excellent in resistance to sulfur poisoning.
【図１】本発明の排気ガス浄化用触媒のモデル図であ
る。FIG. 1 is a model diagram of an exhaust gas purifying catalyst of the present invention.
１…担体 ２…白金粒子 ３…パラジウム又はロジウム粒子 ４…金粒子 DESCRIPTION OF SYMBOLS 1 ... Carrier 2 ... Platinum particle 3 ... Palladium or rhodium particle 4 ... Gold particle
フロントページの続き Ｆターム(参考） 4D048 AA06 AB02 BA03Y BA30X BA30Y BA31X BA31Y BA33X BA33Y BA34X BA34Y BA43Y BA46Y EA04 4G069 AA03 AA08 BA01B BB02A BB02B BB02C BB08B BB10B BC33A BC33B BC33C BC71A BC71B BC71C BC72A BC72B BC72C BC75A BC75B BC75C CA03 CA13 EC12Y ED07 EE08 FA02 FB13 Continued on the front page F-term (reference) 4D048 AA06 AB02 BA03Y BA30X BA30Y BA31X BA31Y BA33X BA33Y BA34X BA34Y BA43Y BA46Y EA04 4G069 AA03 AA08 BA01B BB02A BB02B BB02C BB08B BB10B BC33 BCBC BCBC BCBC BCBC BC BC BC BC BC BC BC BC FA02 FB13
Claims (1)
ウム又はロジウムを含む複合金属粒子が担持され、前記
複合金属粒子の上に金粒子が積相されたことを特徴とす
る排気ガス浄化用触媒。1. Exhaust gas purification, wherein composite metal particles containing platinum and palladium or rhodium are supported on an inorganic oxide carrier, and gold particles are stacked on the composite metal particles. catalyst.
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|---|---|---|---|
| JP2000018016A JP2001205087A (en) | 2000-01-25 | 2000-01-25 | Catalyst for cleaning exhaust gas |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000018016A JP2001205087A (en) | 2000-01-25 | 2000-01-25 | Catalyst for cleaning exhaust gas |
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| Publication Number | Publication Date |
|---|---|
| JP2001205087A true JP2001205087A (en) | 2001-07-31 |
Family
ID=18544923
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003088757A (en) * | 2001-09-19 | 2003-03-25 | Toyota Motor Corp | Catalyst |
| WO2008117941A1 (en) * | 2007-03-28 | 2008-10-02 | Heesung Catalysts Corporation | Doc catalyst employing pd-au for improving diesel oxidation activity |
| JP2009247975A (en) * | 2008-04-04 | 2009-10-29 | Toyota Motor Corp | Automotive exhaust gas treatment catalyst |
| JP2011123004A (en) * | 2009-12-14 | 2011-06-23 | Nippon Soken Inc | Noble metal catalyst powder, gas sensor element using the same, and gas sensor |
| EP3081296A4 (en) * | 2013-12-11 | 2017-08-09 | Cataler Corporation | Exhaust gas purifying catalyst |
| JP2018511458A (en) * | 2015-01-29 | 2018-04-26 | ビーエーエスエフ コーポレーション | Rhodium-containing catalyst for automobile exhaust gas treatment |
-
2000
- 2000-01-25 JP JP2000018016A patent/JP2001205087A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003088757A (en) * | 2001-09-19 | 2003-03-25 | Toyota Motor Corp | Catalyst |
| WO2008117941A1 (en) * | 2007-03-28 | 2008-10-02 | Heesung Catalysts Corporation | Doc catalyst employing pd-au for improving diesel oxidation activity |
| KR100865362B1 (en) * | 2007-03-28 | 2008-10-24 | 희성촉매 주식회사 | Diesel Oxidation Catalyst employing Pd-Au for improving diesel oxidation activity |
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