JP5491745B2 - Exhaust gas purification catalyst and method for producing the same - Google Patents

Exhaust gas purification catalyst and method for producing the same Download PDF

Info

Publication number
JP5491745B2
JP5491745B2 JP2009038843A JP2009038843A JP5491745B2 JP 5491745 B2 JP5491745 B2 JP 5491745B2 JP 2009038843 A JP2009038843 A JP 2009038843A JP 2009038843 A JP2009038843 A JP 2009038843A JP 5491745 B2 JP5491745 B2 JP 5491745B2
Authority
JP
Japan
Prior art keywords
metal
exhaust gas
metal particles
gas purifying
catalyst
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP2009038843A
Other languages
Japanese (ja)
Other versions
JP2010194384A (en
Inventor
豪 濱口
寿幸 田中
正興 岩崎
千和 加藤
健 信川
貴史 夏目
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Toyota Central R&D Labs Inc
Original Assignee
Toyota Motor Corp
Toyota Central R&D Labs Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp, Toyota Central R&D Labs Inc filed Critical Toyota Motor Corp
Priority to JP2009038843A priority Critical patent/JP5491745B2/en
Priority to PCT/JP2010/052909 priority patent/WO2010095761A2/en
Publication of JP2010194384A publication Critical patent/JP2010194384A/en
Application granted granted Critical
Publication of JP5491745B2 publication Critical patent/JP5491745B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9413—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/462—Ruthenium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/464—Rhodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/468—Iridium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/50—Silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/58—Platinum group metals with alkali- or alkaline earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/656—Manganese, technetium or rhenium
    • B01J23/6562—Manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/66—Silver or gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8906—Iron and noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/8946—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali or alkaline earth metals
    • B01J35/393—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B01J37/0205—Impregnation in several steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • B01J37/18—Reducing with gases containing free hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1023—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1025—Rhodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1026—Ruthenium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1028—Iridium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/104—Silver
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/106—Gold
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/202—Alkali metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/202—Alkali metals
    • B01D2255/2022—Potassium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/202—Alkali metals
    • B01D2255/2025—Lithium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/202—Alkali metals
    • B01D2255/2027—Sodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B01D2255/2042—Barium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B01D2255/2045—Calcium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/204—Alkaline earth metals
    • B01D2255/2047—Magnesium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/2073—Manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/207—Transition metals
    • B01D2255/20738—Iron
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9202—Linear dimensions

Description

本発明は、排ガス浄化用触媒、排ガス浄化用触媒の製造方法、並びにその排ガス浄化用触媒を用いた排ガス浄化方法に関する。   The present invention relates to an exhaust gas purifying catalyst, an exhaust gas purifying catalyst manufacturing method, and an exhaust gas purifying method using the exhaust gas purifying catalyst.

従来から、自動車等の排ガスに含まれる有害な窒素酸化物を浄化するためには、窒素酸化物吸蔵還元型触媒が利用されてきた。このような窒素酸化物吸蔵還元型触媒としては、Ｐｔ，Ｐｄ等の触媒活性を有する貴金属粒子と、主にバリウム等のアルカリ土類金属もしくはアルカリ金属とを、アルミナ、ジルコニア等のセラミックスのペレット状もしくはハニカム状成型体やセラミックスをコーティングした金属ハニカムといった多孔質担体上に担持せしめたものが知られている。   Conventionally, nitrogen oxide storage reduction catalysts have been used to purify harmful nitrogen oxides contained in exhaust gas from automobiles and the like. As such a nitrogen oxide occlusion reduction type catalyst, a noble metal particle having catalytic activity such as Pt, Pd and an alkaline earth metal such as barium or an alkali metal, and a ceramic pellet such as alumina or zirconia. Or what was carry | supported on the porous support | carriers, such as a honeycomb-shaped molded object and the metal honeycomb which coated ceramics is known.

しかしながら、このような窒素酸化物吸蔵還元型触媒においては、触媒に吸蔵した窒素酸化物を十分に還元できないという問題が生じていた。   However, such a nitrogen oxide storage reduction type catalyst has a problem that the nitrogen oxide stored in the catalyst cannot be sufficiently reduced.

上記のような問題を解決するために、例えば、特開平１１−１５６１９３号公報（特許文献１）には、金属酸化物からなる担体と、前記担体に担持された金属粒子とを備える排ガス浄化用触媒であり、前記金属粒子が、平均粒子径が３０ｎｍ以下の第一の金属粒子上に第一の金属粒子とは異なる１種以上の金属からなる第二の金属層を被覆率４５％以上となるように積層していることを特徴とした触媒が記載されている。   In order to solve the above problems, for example, Japanese Patent Application Laid-Open No. 11-156193 (Patent Document 1) discloses an exhaust gas purifying apparatus comprising a carrier made of a metal oxide and metal particles carried on the carrier. The catalyst is a catalyst, and the metal particle has a covering ratio of 45% or more on the first metal particle having an average particle diameter of 30 nm or less and made of one or more metals different from the first metal particle. A catalyst characterized in that it is laminated is described.

また、特開２００２−１１１９号公報（特許文献２）や特開２００４−２６７９６１号公報（特許文献３）には、金属酸化物からなる担体と、前記担体に担持された金属粒子とを備える排ガス浄化用触媒であり、前記金属粒子がバイメタリックコロイドを用いて担持されたものであることを特徴とした触媒が記載されている。   Japanese Patent Application Laid-Open No. 2002-1119 (Patent Document 2) and Japanese Patent Application Laid-Open No. 2004-267961 (Patent Document 3) describe an exhaust gas including a carrier made of a metal oxide and metal particles supported on the carrier. There is described a catalyst for purification, wherein the metal particles are supported using a bimetallic colloid.

しかしながら、特許文献１〜３に記載のような触媒であっても、触媒に吸蔵した窒素酸化物を必ずしも十分に還元する能力を有するものではなく、未だ十分なものではなかった。   However, even the catalysts as described in Patent Documents 1 to 3 do not necessarily have the ability to sufficiently reduce the nitrogen oxides occluded in the catalyst, and are not yet sufficient.

特開平１１−１５６１９３号公報JP-A-11-156193 特開２００２−１１１９号公報JP 2002-1119 A 特開２００４−２６７９６１号公報Japanese Patent Application Laid-Open No. 2004-267961

本発明は、上記従来技術の有する課題に鑑みてなされたものであり、自動車等の排ガスに含まれる窒素酸化物を十分に還元する能力を持つ排ガス浄化用触媒、及びその製造方法、並びにそれを用いた排ガス浄化方法を提供することを目的とする。   The present invention has been made in view of the above-described problems of the prior art, and an exhaust gas purifying catalyst having the ability to sufficiently reduce nitrogen oxides contained in exhaust gas of automobiles, a method for producing the same, and It aims at providing the used exhaust gas purification method.

本発明者らは、上記目的を達成すべく鋭意研究を重ねた結果、金属酸化物に担持された金属粒子は窒素酸化物の酸化を促進する第一の金属と窒素酸化物の分解を促進する第二の金属に分類できることを見出すとともに、これらの金属を金属酸化物からなる担体に担持せしめる際に、第一の金属と第二の金属が均一に固溶された構造を有する金属粒子として配置せしめることによって、窒素酸化物を十分に還元する触媒活性を発揮することが可能となることを見出し、本発明を完成するに至った。   As a result of intensive studies to achieve the above object, the present inventors have promoted the decomposition of nitrogen oxides with the first metal that promotes the oxidation of nitrogen oxides. Found to be classified as a second metal, and when these metals are supported on a carrier made of a metal oxide, they are arranged as metal particles having a structure in which the first metal and the second metal are uniformly dissolved. As a result, it has been found that the catalytic activity to sufficiently reduce nitrogen oxides can be exhibited, and the present invention has been completed.

すなわち、本発明の排ガス浄化用触媒は、金属酸化物からなる担体と、前記担体に担持された金属粒子とを備える排ガス浄化用触媒であって、
前記金属粒子が、Ｐｔである第一の金属と、Ｐｄである第二の金属との固溶体からなり、
前記金属粒子の平均一次粒子径が１．５ｎｍ以下であり、
前記金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であり、且つ、
前記担体に、Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ及びＢａからなる群から選択される少なくとも一種の第三の金属が更に担持されていること、
を特徴とするものである。 That is, the exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst comprising a carrier made of a metal oxide and metal particles supported on the carrier,
Wherein the metal particles are made of a solid solution of the first metal is P t, the second metal is P d,
The average primary particle diameter of the metal particles is 1.5 nm or less,
The standard deviation of the metal composition ratio for each primary particle in the metal particles is 10% or less, and
The carrier further carries at least one third metal selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba ,
It is characterized by.

本発明の排ガス浄化用触媒の製造方法は、
Ｐｔである第一の金属と、Ｐｄである第二の金属とのうちいずれか一方の金属からなる粒子を金属酸化物からなる担体に担持せしめる工程と、
前記金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中で５０℃以上に加熱して前記金属粒子に水素を固溶せしめる工程と、
前記水素が固溶した金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中に維持しつつ前記第一の金属と前記第二の金属とのうち他方の金属のイオンを含有する溶液中に浸漬せしめ、前記金属粒子に固溶している水素により前記他方の金属を還元せしめることにより、前記第一の金属と前記第二の金属との固溶体からなる金属粒子を前記担体に担持せしめる工程と、
前記固溶体からなる金属粒子を担持した担体に、Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ及びＢａからなる群から選択される少なくとも一種の第三の金属を担持せしめて排ガス浄化用触媒を得る工程と、
を含むことを特徴とする方法である。
The method for producing the exhaust gas purifying catalyst of the present invention comprises:
A step of supporting particles made of any one of a first metal being Pt and a second metal being Pd on a carrier made of a metal oxide;
Heating the support carrying the metal particles to 50 ° C. or more in an atmosphere having a hydrogen concentration of 0.5% by volume or more to cause hydrogen to be dissolved in the metal particles;
While maintaining the carrier carrying the metal particles in which hydrogen is dissolved in an atmosphere having a hydrogen concentration of 0.5% by volume or more, ions of the other metal out of the first metal and the second metal A metal particle comprising the solid solution of the first metal and the second metal is obtained by immersing it in a solution containing it and reducing the other metal with hydrogen dissolved in the metal particle. A process of supporting the
Exhaust gas by supporting at least one third metal selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba on a carrier supporting metal particles made of the solid solution. Obtaining a purification catalyst;
It is the method characterized by including.

上記本発明の製造方法によれば、前記固溶体からなる金属粒子の平均一次粒子径が１．５ｎｍ以下であり、且つ、前記固溶体からなる金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であることを特徴とする排ガス浄化用触媒を得ることが可能となる。   According to the production method of the present invention, the average primary particle diameter of the metal particles made of the solid solution is 1.5 nm or less, and the standard deviation of the metal composition ratio for each primary particle in the metal particles made of the solid solution is 10 %, It is possible to obtain an exhaust gas purifying catalyst characterized by being less than or equal to%.

本発明の排ガス浄化方法は、酸素過剰雰囲気下において、前記本発明の排ガス浄化用触媒に排ガスを接触せしめて前記排ガス中の窒素酸化物を浄化することを特徴とする方法である。   The exhaust gas purification method of the present invention is a method characterized by purifying nitrogen oxides in the exhaust gas by bringing the exhaust gas into contact with the exhaust gas purification catalyst of the present invention in an oxygen-excess atmosphere.

なお、本発明の排ガス浄化用触媒においては前記金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であることが必要であるが、かかる標準偏差は、触媒上の金属粒子の一次粒子から測定対象とする一次粒子を任意に１５個抽出し、ＴＥＭ−ＥＤＸ分析によってそれらの一次粒子における金属組成比を測定し、得られた金属組成比の分布の標準偏差を算出することによって得られたものである。   In the exhaust gas purifying catalyst of the present invention, the standard deviation of the metal composition ratio for each primary particle in the metal particles needs to be 10% or less. The standard deviation is the primary metal particle on the catalyst. Obtained by arbitrarily extracting 15 primary particles to be measured from the particles, measuring the metal composition ratio in the primary particles by TEM-EDX analysis, and calculating the standard deviation of the distribution of the obtained metal composition ratio It is what was done.

ここで測定点（測定対象とする一次粒子の数）を１５個とした理由は、観察視野を変えて、且つ、測定点を１５個より増やして金属組成比の標準偏差を算出した場合であっても、得られた標準偏差と測定点を１５個として得られた標準偏差との間に有意な差が無かったため、測定点を１５個として得られた標準偏差であれば十分に再現性が得られると判断したためである。   The reason why the number of measurement points (the number of primary particles to be measured) is 15 is that when the observation field is changed and the number of measurement points is increased from 15 to calculate the standard deviation of the metal composition ratio. However, since there was no significant difference between the standard deviation obtained and 15 standard deviations, the standard deviation obtained with 15 measurement points was sufficiently reproducible. It was because it was judged that it was obtained.

また、本発明において採用するＴＥＭ−ＥＤＸ分析においては、測定装置として、従来公知の透過型電子顕微鏡（ＴＥＭ）に、従来公知のエネルギー分散型Ｘ線分光器（ＥＤＸ分析装置）を装備したＴＥＭ−ＥＤＸ装置を用いることができる。   In the TEM-EDX analysis employed in the present invention, a TEM- equipped with a conventionally known transmission electron microscope (TEM) as a measuring device and a conventionally known energy dispersive X-ray spectrometer (EDX analyzer). An EDX device can be used.

このようなＴＥＭ−ＥＤＸ分析においては、先ず、ＴＥＭ−ＥＤＸ装置を用いて、前記排ガス浄化用触媒上の測定対象とする金属粒子に対して、ビーム径が１〜２ｎｍの測定点内のエネルギー分散型の蛍光Ｘ線スペクトルから、第一の金属元素に由来するピークの面積と、第二の金属元素に由来するピークの面積とを求め、第一の金属元素に由来するピーク面積と第二の金属元素のピーク面積との和に対する第一の金属元素のピークの面積の比（ピーク面積比（％））を求める。このようにして得られたピーク面積比が、測定対象とした金属粒子における一次粒子の金属組成比に相当する。   In such a TEM-EDX analysis, first, using a TEM-EDX apparatus, energy dispersion within a measurement point with a beam diameter of 1 to 2 nm is applied to the metal particles to be measured on the exhaust gas purification catalyst. The peak area derived from the first metal element and the peak area derived from the second metal element are determined from the fluorescent X-ray spectrum of the mold, and the peak area derived from the first metal element and the second area The ratio of the peak area of the first metal element to the sum of the peak area of the metal element (peak area ratio (%)) is obtained. The peak area ratio thus obtained corresponds to the metal composition ratio of the primary particles in the metal particles to be measured.

なお、このようなピーク面積比は、下記式：
［ピーク面積比（％）］＝｛［第一の金属元素のピーク面積］／（［第一の金属元素のピーク面積］＋［第二の金属元素のピーク面積］）｝×１００
に基づいて計算することにより算出できる。また、ここに言う「ピーク」とは、前記スペクトルのベースラインからピークトップまでの高さの強度差が１ｃｔｓ以上のものを言う。また、このようなピークとしては、例えば、金属元素がＰｔである場合にはエネルギーが２．０４８ｋｅＶの位置（ＰｔＭα線）に現れ、金属元素がＰｄである場合には２．８３８ｋｅＶの位置（ＰｄＬα線）に現れる。 In addition, such a peak area ratio is represented by the following formula:
[Peak area ratio (%)] = {[peak area of the first metal element] / ([peak area of the first metal element] + [peak area of the second metal element])} × 100
It can calculate by calculating based on. Further, the “peak” mentioned here refers to a peak having a height difference of 1 cts or more from the baseline of the spectrum to the peak top. Further, as such a peak, for example, when the metal element is Pt, the energy appears at a position of 2.048 keV (PtMα line), and when the metal element is Pd, the position of 2.838 keV (PdLα Appear on the line).

次に、このようにして得られたピーク面積比の分布の標準偏差を求める。すなわち、任意の１５点以上の測定点においてＴＥＭ−ＥＤＸ分析を行って、各測定点における上記ピーク面積比を求め、得られたピーク面積比に基づいて、ピーク面積比の分布の標準偏差（％）を算出することにより求めることができる。   Next, the standard deviation of the distribution of the peak area ratio thus obtained is obtained. That is, a TEM-EDX analysis is performed at any 15 or more measurement points to determine the peak area ratio at each measurement point, and based on the obtained peak area ratio, the standard deviation (% ) Can be obtained.

本発明の排ガス浄化用触媒においては、このようなピーク面積比の分布の標準偏差（金属粒子における一次粒子毎の金属組成比の標準偏差）が１０％以下である。このような標準偏差が１０％を超えている排ガス浄化用触媒においては、第一の金属と第二の金属が十分に均一に固溶したものとはなっておらず、吸蔵した窒素酸化物の還元能力が十分なものとはならない。   In the exhaust gas purifying catalyst of the present invention, the standard deviation of the distribution of the peak area ratio (standard deviation of the metal composition ratio for each primary particle in the metal particles) is 10% or less. In such an exhaust gas purifying catalyst with a standard deviation exceeding 10%, the first metal and the second metal are not sufficiently homogeneously dissolved, and the occluded nitrogen oxide The reduction ability is not sufficient.

また、本発明の排ガス浄化用触媒においては、前記金属粒子の平均一次粒子径が１．５ｎｍ以下であることが必要であるが、かかる平均一次粒子径は従来公知のＣＯ化学吸着法により求めることができる。このような金属粒子の平均一次粒子径が１．５ｎｍを超えている排ガス浄化用触媒においては、窒素酸化物の吸蔵や還元が十分に促進されなくなる。   In the exhaust gas purifying catalyst of the present invention, the average primary particle size of the metal particles needs to be 1.5 nm or less. The average primary particle size is determined by a conventionally known CO chemical adsorption method. Can do. In such an exhaust gas purifying catalyst in which the average primary particle diameter of the metal particles exceeds 1.5 nm, occlusion and reduction of nitrogen oxides are not sufficiently promoted.

なお、本発明の排ガス浄化用触媒によって、十分に優れた窒素酸化物の還元性能が達成される理由は必ずしも定かではないが、本発明者らは以下のように推察する。すなわち、本発明の排ガス浄化用触媒においては、窒素酸化物の酸化を促進する第一の金属と窒素酸化物の分解を促進する第二の金属とが、小さい一次粒子からなる金属粒子内で均一に固溶しているため、窒素酸化物の酸化と還元を同一の金属粒子上で効率良く且つ確実に進行せしめることが可能となり、結果として十分に高い窒素酸化物浄化活性が得られると本発明者らは推察する。   The reason why sufficiently excellent nitrogen oxide reduction performance is achieved by the exhaust gas purifying catalyst of the present invention is not necessarily clear, but the present inventors speculate as follows. That is, in the exhaust gas purifying catalyst of the present invention, the first metal that promotes oxidation of nitrogen oxides and the second metal that promotes decomposition of nitrogen oxides are uniform in the metal particles composed of small primary particles. Therefore, the oxidation and reduction of nitrogen oxides can proceed efficiently and reliably on the same metal particle, and as a result, a sufficiently high nitrogen oxide purification activity can be obtained. They guess.

本発明によれば、自動車等の排ガスに含まれる窒素酸化物を十分に還元する能力を持つ排ガス浄化用触媒、及びその製造方法、並びにそれを用いた排ガス浄化方法を提供することが可能となる。   ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the exhaust gas purification catalyst which has the capability to fully reduce | restore the nitrogen oxide contained in exhaust gas, such as a motor vehicle, the manufacturing method, and the exhaust gas purification method using the same. .

実施例１で得られた排ガス浄化用触媒の表面上の特定領域の状態を示す透過型電子顕微鏡（ＴＥＭ）写真である。2 is a transmission electron microscope (TEM) photograph showing the state of a specific region on the surface of the exhaust gas purifying catalyst obtained in Example 1. FIG. 実施例１で得られた排ガス浄化用触媒の表面上の特定領域の状態を示す透過型電子顕微鏡（ＴＥＭ）写真である。2 is a transmission electron microscope (TEM) photograph showing the state of a specific region on the surface of the exhaust gas purifying catalyst obtained in Example 1. FIG. 実施例１で得られた排ガス浄化用触媒の表面上の特定領域の状態を示す透過型電子顕微鏡（ＴＥＭ）写真である。2 is a transmission electron microscope (TEM) photograph showing the state of a specific region on the surface of the exhaust gas purifying catalyst obtained in Example 1. FIG. 比較例１で得られた排ガス浄化用触媒の表面上の特定領域の状態を示す透過型電子顕微鏡（ＴＥＭ）写真である。4 is a transmission electron microscope (TEM) photograph showing the state of a specific region on the surface of an exhaust gas purifying catalyst obtained in Comparative Example 1. 比較例１で得られた排ガス浄化用触媒の表面上の特定領域の状態を示す透過型電子顕微鏡（ＴＥＭ）写真である。4 is a transmission electron microscope (TEM) photograph showing the state of a specific region on the surface of an exhaust gas purifying catalyst obtained in Comparative Example 1. 比較例１で得られた排ガス浄化用触媒の表面上の特定領域の状態を示す透過型電子顕微鏡（ＴＥＭ）写真である。4 is a transmission electron microscope (TEM) photograph showing the state of a specific region on the surface of an exhaust gas purifying catalyst obtained in Comparative Example 1. 実施例１で得られた排ガス浄化用触媒の金属粒子の表面上の測定点００１〜００５におけるエネルギー分散型の蛍光Ｘ線スペクトルを示すグラフである。2 is a graph showing an energy dispersive fluorescent X-ray spectrum at measurement points 001 to 005 on the surface of metal particles of the exhaust gas purifying catalyst obtained in Example 1. FIG. 比較例１で得られた排ガス浄化用触媒の金属粒子の表面上の測定点００１〜００５におけるエネルギー分散型の蛍光Ｘ線スペクトルを示すグラフである。6 is a graph showing an energy dispersive fluorescent X-ray spectrum at measurement points 001 to 005 on the surface of metal particles of an exhaust gas purifying catalyst obtained in Comparative Example 1. ３００℃の温度条件下における実施例１及び比較例１で得られた排ガス浄化用触媒の窒素酸化物浄化率を示すグラフである。It is a graph which shows the nitrogen oxide purification | cleaning rate of the catalyst for exhaust gas purification obtained in Example 1 and the comparative example 1 on 300 degreeC temperature conditions. ３５０℃の温度条件下における実施例１〜５及び比較例２で得られた排ガス浄化用触媒の窒素酸化物浄化率を示すグラフである。It is a graph which shows the nitrogen oxide purification | cleaning rate of the catalyst for exhaust gas purification obtained in Examples 1-5 and the comparative example 2 on 350 degreeC temperature conditions. 実施例１〜５及び比較例３で得られた排ガス浄化用触媒における金属粒子の平均一次粒子径を示すグラフである。6 is a graph showing average primary particle diameters of metal particles in exhaust gas purifying catalysts obtained in Examples 1 to 5 and Comparative Example 3.

以下、本発明をその好適な実施形態に即して詳細に説明する。   Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

先ず、本発明の排ガス浄化用触媒について説明する。すなわち、本発明の排ガス浄化用触媒は、金属酸化物からなる担体と、前記担体に担持された金属粒子とを備える排ガス浄化用触媒であって、
前記金属粒子が、Ｐｔ，Ａｇ，Ｍｎ，Ｆｅ及びＡｕからなる群から選択される少なくとも一種の第一の金属と、Ｐｄ，Ｒｈ，Ｉｒ及びＲｕからなる群から選択される少なくとも一種の第二の金属との固溶体からなり、
前記金属粒子の平均一次粒子径が１．５ｎｍ以下であり、且つ、
前記金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であることを特徴とする。 First, the exhaust gas purifying catalyst of the present invention will be described. That is, the exhaust gas purifying catalyst of the present invention is an exhaust gas purifying catalyst comprising a carrier made of a metal oxide and metal particles supported on the carrier,
The metal particles are at least one second metal selected from the group consisting of Pt, Ag, Mn, Fe and Au, and at least one second selected from the group consisting of Pd, Rh, Ir and Ru. Made of solid solution with metal,
The average primary particle diameter of the metal particles is 1.5 nm or less, and
The standard deviation of the metal composition ratio for each primary particle in the metal particles is 10% or less.

本発明において用いる第一の金属は、窒素酸化物の酸化を促進する金属であって、Ｐｔ，Ａｇ，Ｍｎ，Ｆｅ及びＡｕからなる群から選択される少なくとも一種であり、中でも、得られる触媒における窒素酸化物の酸化促進能力がより向上する傾向にあるという観点から、Ｐｔであることがより好ましい。なお、このような第一の金属は、一種を単独で、あるいは二種以上を混合して用いてもよい。   The first metal used in the present invention is a metal that promotes oxidation of nitrogen oxides, and is at least one selected from the group consisting of Pt, Ag, Mn, Fe, and Au. From the viewpoint that the oxidation promotion ability of nitrogen oxides tends to be further improved, Pt is more preferable. In addition, you may use such 1st metal individually by 1 type or in mixture of 2 or more types.

また、本発明において用いる第二の金属は、窒素酸化物の還元を促進する金属であって、Ｐｄ，Ｒｈ，Ｉｒ及びＲｕからなる群から選択される少なくとも一種であり、中でも、得られる触媒における窒素酸化物の還元促進能力がより向上する傾向にあるという観点から、Ｐｄであることがより好ましい。なお、このような第二の金属は、一種を単独で、あるいは二種以上を混合して用いてもよい。   Further, the second metal used in the present invention is a metal that promotes reduction of nitrogen oxides, and is at least one selected from the group consisting of Pd, Rh, Ir, and Ru. From the viewpoint that the reduction promotion ability of nitrogen oxides tends to be further improved, Pd is more preferable. In addition, you may use such a 2nd metal individually by 1 type or in mixture of 2 or more types.

本発明の触媒においては、前記第一の金属と前記第二の金属とが、それらの固溶体からなる金属粒子として担体に担持されている必要がある。このような金属粒子の構造である固溶体とは、複数の元素（前記第一の金属と前記第二の金属）が互いに溶け合って固相をなしているものをいう。このような固溶体を構成する前記第一の金属と前記第二の金属との組成比としては、特に制限されないが、前記第一の金属と前記第二の金属との合計原子数に対して前記第二の金属の原子の割合が１０〜９０原子％であることが好ましい。前記第二の金属の濃度が前記下限未満では、得られる触媒による窒素酸化物の還元が十分に促進されなくなる傾向にあり、他方、前記上限を超えると、得られる触媒による窒素酸化物の酸化が十分に促進されなくなる傾向にある。   In the catalyst of the present invention, the first metal and the second metal need to be supported on a carrier as metal particles made of a solid solution thereof. The solid solution having such a metal particle structure is a solid solution in which a plurality of elements (the first metal and the second metal) are melted together to form a solid phase. The composition ratio of the first metal and the second metal constituting such a solid solution is not particularly limited, but the total number of atoms of the first metal and the second metal is It is preferable that the ratio of the atom of a 2nd metal is 10-90 atomic%. If the concentration of the second metal is less than the lower limit, the reduction of nitrogen oxides by the resulting catalyst tends not to be sufficiently promoted. There is a tendency not to be fully promoted.

さらに、本発明の触媒においては前記金属粒子の平均一次粒子径が１．５ｎｍ以下であることが必要であり、０．３〜１．３ｎｍであることがより好ましい。前記金属粒子の平均一次粒子径が１．５ｎｍを超えると、得られる触媒による窒素酸化物の吸蔵もしくは還元が十分に促進されなくなる。   Furthermore, in the catalyst of the present invention, the average primary particle diameter of the metal particles needs to be 1.5 nm or less, and more preferably 0.3 to 1.3 nm. When the average primary particle diameter of the metal particles exceeds 1.5 nm, the absorption or reduction of nitrogen oxides by the obtained catalyst is not sufficiently promoted.

さらに、本発明の触媒においては前記金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であることが必要であり、８％以下であることがより好ましい。前記金属組成比の標準偏差が１０％を超えると、得られる触媒による窒素酸化物の酸化もしくは還元が十分に促進されなくなる。   Furthermore, in the catalyst of the present invention, the standard deviation of the metal composition ratio for each primary particle in the metal particles needs to be 10% or less, and more preferably 8% or less. When the standard deviation of the metal composition ratio exceeds 10%, the oxidation or reduction of nitrogen oxides by the obtained catalyst is not sufficiently promoted.

本発明の排ガス浄化用触媒は、前述の金属粒子が金属酸化物からなる担体に担持されてなるものである。本発明の排ガス浄化用触媒において、担体に担持される金属粒子の量は特に制限されないが、前記担体１００質量部に対して金属粒子の量が０．０５〜１０質量部であることが好ましく、０．１〜５質量部であることがより好ましい。前記金属粒子の担持量が前記下限未満では、前記金属粒子により得られる触媒活性が不十分となる傾向にあり、他方、前記上限を超えると、コストが高騰すると共に前記金属粒子の粒成長が起こりやすくなる傾向にある。   The exhaust gas purifying catalyst of the present invention is formed by supporting the above-mentioned metal particles on a carrier made of a metal oxide. In the exhaust gas purifying catalyst of the present invention, the amount of metal particles supported on the carrier is not particularly limited, but the amount of metal particles is preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of the carrier, It is more preferable that it is 0.1-5 mass parts. When the loading amount of the metal particles is less than the lower limit, the catalytic activity obtained by the metal particles tends to be insufficient. On the other hand, when the upper limit is exceeded, the cost increases and grain growth of the metal particles occurs. It tends to be easier.

また、本発明の排ガス浄化用触媒においては、Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ及びＢａからなる群から選択される少なくとも一種の第三の金属が前記担体に更に担持されていることが好ましい。このような第三の金属は高い塩基性を有しているため、その酸化物を形成させた際に十分に高い窒素酸化物吸蔵能が発揮されるようになるという観点から前記第三の金属を用いることが好ましく、中でもＢａを用いることがより好ましい。なお、このような第三の金属は、一種を単独で、あるいは２種以上を混合して用いてもよい。   In the exhaust gas purifying catalyst of the present invention, at least one third metal selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba is further added to the carrier. It is preferably supported. Since such a third metal has a high basicity, when the oxide is formed, a sufficiently high nitrogen oxide storage capacity is exhibited from the viewpoint of the third metal. Is preferable, and Ba is more preferable. In addition, you may use such a 3rd metal individually by 1 type or in mixture of 2 or more types.

本発明の排ガス浄化用触媒において、担体に担持される第三の金属の量は特に制限されないが、担体の容積に対して０．０５ｍｏｌ／Ｌ以上であることが好ましく、０．１ｍｏｌ／Ｌ〜２．０ｍｏｌ／Ｌであることがより好ましい。第三の金属の担持量が前記下限未満では、得られる触媒による窒素酸化物吸蔵量が不十分となる傾向にあり、他方、前記上限を超えると、前記金属粒子の触媒活性が低下する傾向にある。   In the exhaust gas purifying catalyst of the present invention, the amount of the third metal supported on the carrier is not particularly limited, but is preferably 0.05 mol / L or more with respect to the volume of the carrier, 0.1 mol / L to More preferably, it is 2.0 mol / L. If the amount of the third metal supported is less than the lower limit, the amount of nitrogen oxide stored by the resulting catalyst tends to be insufficient. On the other hand, if the amount exceeds the upper limit, the catalytic activity of the metal particles tends to decrease. is there.

本発明において採用する金属酸化物からなる担体としては特に制限されず、アルミナ、ジルコニア、チタニア等が好ましい。さらに、本発明にかかる担体の形状としては特に制限されないが、比表面積が向上し、より高い触媒活性が得られることから、粉体状であることが好ましい。このような担体が粉体状のものである場合においては、前記担体の粒度（二次粒子径）は特に制限されず、１〜１００μｍであることが好ましい。担体の粒子径が前記下限未満では、担体の微細化にコストがかかると共に、その扱いが困難となる傾向にあり、他方、前記上限を超えると、後述するような基材に本発明の排ガス浄化用触媒のコート層を安定に形成させることが困難となる傾向にある。   The carrier made of a metal oxide employed in the present invention is not particularly limited, and alumina, zirconia, titania and the like are preferable. Furthermore, the shape of the carrier according to the present invention is not particularly limited, but is preferably in the form of a powder because the specific surface area is improved and higher catalytic activity is obtained. When such a carrier is in powder form, the particle size (secondary particle size) of the carrier is not particularly limited, and is preferably 1 to 100 μm. If the particle diameter of the carrier is less than the lower limit, it is costly to make the carrier finer and its handling tends to be difficult. On the other hand, if the upper limit is exceeded, the exhaust gas purification of the present invention is applied to a substrate as described later. It tends to be difficult to form a coating layer of the catalyst for use stably.

また、このような担体の比表面積は、２０ｍ２／ｇ以上であることが好ましく、５０〜３００ｍ２／ｇであることが更に好ましい。担体の比表面積が前記下限未満では、十分な触媒活性を発揮させるために妥当な量の酸化還元能を有する前記金属粒子を担持することが困難となる傾向にあり、他方、前記上限を超えると、熱劣化による比表面積低下が大きくなる傾向にある。なお、このような比表面積は吸着等温線からＢＥＴ等温吸着式を用いてＢＥＴ比表面積として算出することができる。 The specific surface area of such carriers is preferably at 20 m 2 / g or more, more preferably 50 to 300 m 2 / g. If the specific surface area of the support is less than the lower limit, it tends to be difficult to support the metal particles having an appropriate amount of redox ability to exert sufficient catalytic activity, and on the other hand, if the upper limit is exceeded. There is a tendency for the specific surface area to decrease due to thermal degradation. Such a specific surface area can be calculated as a BET specific surface area from an adsorption isotherm using a BET isotherm adsorption equation.

以上、本発明の排ガス浄化用触媒について説明したが、次に、本発明の排ガス浄化用触媒の製造方法について説明する。   The exhaust gas purifying catalyst of the present invention has been described above. Next, the method for producing the exhaust gas purifying catalyst of the present invention will be described.

本発明の排ガス浄化用触媒の製造方法は、
（１）Ｐｔ，Ａｇ，Ｍｎ，Ｆｅ及びＡｕからなる群から選択される少なくとも一種の第一の金属と、Ｐｄ，Ｒｈ，Ｉｒ及びＲｕからなる群から選択される少なくとも一種の第二の金属とのうちいずれか一方の金属からなる粒子を金属酸化物からなる担体に担持せしめる工程（第一の工程）と、
（２）前記金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中で５０℃以上に加熱して前記金属粒子に水素を固溶せしめる工程（第二の工程）と、
（３）前記水素が固溶した金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中に維持しつつ前記第一の金属と前記第二の金属とのうち他方の金属のイオンを含有する溶液中に浸漬せしめ、前記金属粒子に固溶している水素により前記他方の金属を還元せしめることにより、前記第一の金属と前記第二の金属との固溶体からなる金属粒子が前記担体に担持されている排ガス浄化用触媒を得る工程（第三の工程）と、
を含むことを特徴とする。 The method for producing the exhaust gas purifying catalyst of the present invention comprises:
(1) at least one first metal selected from the group consisting of Pt, Ag, Mn, Fe and Au, and at least one second metal selected from the group consisting of Pd, Rh, Ir and Ru; A step (first step) of supporting particles made of any one of the metals on a carrier made of a metal oxide,
(2) heating the carrier carrying the metal particles to 50 ° C. or higher in an atmosphere having a hydrogen concentration of 0.5% by volume or more to cause hydrogen to be dissolved in the metal particles (second step);
(3) The other metal of the first metal and the second metal while maintaining the carrier carrying the metal particles in which the hydrogen is dissolved in an atmosphere having a hydrogen concentration of 0.5% by volume or more. Metal particles comprising a solid solution of the first metal and the second metal by dipping in a solution containing the ions of the metal and reducing the other metal with hydrogen dissolved in the metal particles A step of obtaining an exhaust gas purifying catalyst carried on the carrier (third step);
It is characterized by including.

第一の工程は、前記担体に前記第一の金属もしくは前記第二の金属からなる粒子を担持させることができればよく、具体的な方法は特に制限されない。このような工程として好適な方法としては、例えば、前記第一の金属もしくは前記第二の金属がイオン状に溶解している溶液（例えば、ジニトロジアンミン白金錯体溶液や硝酸パラジウム溶液）に、前記担体を浸して撹拌することによって前記金属を担体に選択吸着せしめる方法が挙げられる。このような溶液を作製する際には、前記第一の金属もしくは前記第二の金属の塩（硝酸塩、酢酸塩、炭酸塩等）、錯体（ジニトロジアンミン錯体等）、水酸化物等の金属化合物が好適に使用される。また、前記溶液を作製するときに用いる溶媒としては、前記第一の金属もしくは前記第二の金属がイオン状に溶解すればよく、特に制限されないが、前記担体との親和性の高さから水であることが好ましい。さらに、前記溶液における前記金属の濃度は、１質量％以下であることが好ましく、０．００５〜０．５質量％であることがより好ましい。前記濃度が１質量％を超えると、前記担体に前記第一の金属もしくは前記第二の金属が均一に担持されにくくなる傾向にある。また、第一の工程における処理時間は特に制限されないが、一般的には０．５〜３時間程度が好適に採用される。   The first step is not particularly limited as long as the first metal or the particles made of the second metal can be supported on the carrier. As a suitable method for such a process, for example, the carrier is added to a solution in which the first metal or the second metal is dissolved in an ionic state (for example, a dinitrodiammine platinum complex solution or a palladium nitrate solution). And a method in which the metal is selectively adsorbed on the support by dipping and stirring. When preparing such a solution, the first metal or the second metal salt (nitrate, acetate, carbonate, etc.), complex (dinitrodiammine complex, etc.), metal compound such as hydroxide, etc. Are preferably used. Further, the solvent used for preparing the solution is not particularly limited as long as the first metal or the second metal is dissolved in an ionic form, but water is used because of its high affinity with the carrier. It is preferable that Furthermore, the concentration of the metal in the solution is preferably 1% by mass or less, and more preferably 0.005 to 0.5% by mass. When the concentration exceeds 1% by mass, the first metal or the second metal tends to be difficult to be uniformly supported on the carrier. Moreover, the processing time in the first step is not particularly limited, but generally about 0.5 to 3 hours is preferably employed.

このような第一の工程によって、前記第一の金属もしくは前記第二の金属が、平均一次粒子径が１．５ｎｍ以下（より好ましくは０．３〜１．３ｎｍ）の金属粒子として前記担体に均一に担持されることとなる。そして、前記金属粒子を担持した担体を、必要に応じて８０〜１５０℃で２〜４８時間程度の乾燥処理を施した後に、以下の第二の工程に供する。   By such a first step, the first metal or the second metal is applied to the carrier as metal particles having an average primary particle diameter of 1.5 nm or less (more preferably 0.3 to 1.3 nm). It will be supported uniformly. And the support | carrier which carry | supported the said metal particle is used for the following 2nd processes, after giving a drying process for about 2-48 hours at 80-150 degreeC as needed.

第二の工程は、前記金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中で５０℃以上に加熱して前記金属粒子に水素を固溶せしめる工程である。第二の工程では、水素濃度が０．５容量％以上の雰囲気であることが必要であり、１〜６容量％の雰囲気であることがより好ましい。水素濃度が０．５容量％未満では、金属粒子に十分に水素を固溶させることができない。一方、水素濃度が６容量％を超えると、水素の爆発限界濃度を超えるため危険となる傾向にあり、また、それを超えた濃度にしても得られる効果の更なる向上は期待されない傾向にある。また、第二の工程における処理温度は５０℃以上であることが必要であり、１００℃〜５００℃であることがより好ましい。処理温度が５０℃未満では、金属粒子に十分に水素を固溶させることができない。一方、処理温度が５００℃を超えると、金属粒子がシンタリングして金属粒子の平均一次粒子径が大きくなる傾向にある。さらに、第二の工程における処理時間としては、処理温度によって異なるものであるため特に制限されないが、一般的には１〜５時間程度が好適に採用される。また、第二の工程において用いられる水素以外のバランスガスは、不活性ガスであることが好ましく、窒素やヘリウムであることがより好ましい。   The second step is a step in which the carrier carrying the metal particles is heated to 50 ° C. or higher in an atmosphere having a hydrogen concentration of 0.5% by volume or higher so that hydrogen is dissolved in the metal particles. In the second step, the atmosphere needs to have a hydrogen concentration of 0.5% by volume or more, and more preferably 1 to 6% by volume. When the hydrogen concentration is less than 0.5% by volume, hydrogen cannot be sufficiently dissolved in the metal particles. On the other hand, when the hydrogen concentration exceeds 6% by volume, it tends to be dangerous because it exceeds the explosion limit concentration of hydrogen, and even if the concentration exceeds that, there is a tendency that further improvement of the obtained effect is not expected. . Moreover, the processing temperature in a 2nd process needs to be 50 degreeC or more, and it is more preferable that it is 100 to 500 degreeC. When the treatment temperature is less than 50 ° C., hydrogen cannot be sufficiently dissolved in the metal particles. On the other hand, when the treatment temperature exceeds 500 ° C., the metal particles are sintered and the average primary particle diameter of the metal particles tends to increase. Furthermore, the treatment time in the second step is not particularly limited because it varies depending on the treatment temperature, but generally about 1 to 5 hours is suitably employed. In addition, the balance gas other than hydrogen used in the second step is preferably an inert gas, and more preferably nitrogen or helium.

このような第二の工程によって前記金属粒子に固溶される水素の量は特に制限されないが、以下の第三の工程において十分な量の金属を還元することができる量の水素が前記金属粒子に均一に固溶されることが好ましい。そして、前記水素が固溶した金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中に維持しつつ、以下の第三の工程に供する。   The amount of hydrogen dissolved in the metal particles in the second step is not particularly limited, but an amount of hydrogen that can reduce a sufficient amount of metal in the following third step is the metal particles. It is preferable that the solid solution is uniformly dissolved. And the support | carrier which carry | supported the metal particle which the said solid solution of hydrogen was carried out is used for the following 3rd processes, maintaining in the atmosphere whose hydrogen concentration is 0.5 volume% or more.

第三の工程は、前記水素が固溶した金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中に維持しつつ前記第一の金属と前記第二の金属とのうち他方の金属のイオンを含有する溶液中に浸漬せしめ、前記金属粒子に固溶している水素により前記他方の金属を還元せしめることにより、前記第一の金属と前記第二の金属との固溶体からなる金属粒子が前記担体に担持されている排ガス浄化用触媒を得る工程である。前記担体を水素濃度が０．５容量％以上の雰囲気中に維持する方法としては、水素濃度が０．５容量％を超える他の雰囲気に前記担体が曝されることが無ければよく、特に制限されない。このような方法としては、前記担体を水素濃度が０．５容量％以上の雰囲気にある容器に封入して移動させ、前記担体をその容器から以下の溶液中に直接浸漬せしめる方法が好適に採用される。   In the third step, among the first metal and the second metal, the carrier carrying the metal particles in which the hydrogen is dissolved is maintained in an atmosphere having a hydrogen concentration of 0.5% by volume or more. From the solid solution of the first metal and the second metal by immersing in a solution containing ions of the other metal and reducing the other metal by hydrogen dissolved in the metal particles. This is a step of obtaining an exhaust gas purifying catalyst in which the metal particles are supported on the carrier. As a method for maintaining the carrier in an atmosphere having a hydrogen concentration of 0.5% by volume or more, it is sufficient that the carrier is not exposed to other atmospheres in which the hydrogen concentration exceeds 0.5% by volume. Not. As such a method, a method in which the carrier is enclosed in a container having an hydrogen concentration of 0.5% by volume or more and moved, and the carrier is directly immersed in the following solution from the container is suitably employed. Is done.

第三の工程においては、前記第一の金属と前記第二の金属とのうち、前記第一の工程において用いられなかった方の金属（他方の金属）がイオン状に溶解している溶液（例えば、ジニトロジアンミン白金錯体溶液や硝酸パラジウム溶液）が用いられる。このような溶液を作製する際には、前記他方の金属の塩（硝酸塩、酢酸塩、炭酸塩等）、錯体（ジニトロジアンミン錯体等）、水酸化物等の金属化合物が好適に使用される。また、前記溶液を作製するときに用いる溶媒としては、前記他方の金属がイオン状に溶解すればよく、特に制限されないが、前記担体との親和性の高さから水であることが好ましい。さらに、前記溶液における前記他方の金属の濃度は、１質量％以下であることが好ましく、０．００５〜０．５質量％であることがより好ましい。前記濃度が１質量％を超えると、前記金属粒子上に前記他方の金属が均一に析出されにくくなる傾向にある。また、第三の工程における処理時間は特に制限されないが、一般的には０．５〜３時間程度が好適に採用される。   In the third step, a solution in which one of the first metal and the second metal that has not been used in the first step (the other metal) is dissolved in an ionic state ( For example, dinitrodiammine platinum complex solution or palladium nitrate solution) is used. In preparing such a solution, a metal compound such as a salt of the other metal (nitrate, acetate, carbonate, etc.), a complex (dinitrodiammine complex, etc.) or a hydroxide is preferably used. The solvent used for preparing the solution is not particularly limited as long as the other metal is dissolved in an ionic form, but is preferably water because of its high affinity with the carrier. Furthermore, the concentration of the other metal in the solution is preferably 1% by mass or less, and more preferably 0.005 to 0.5% by mass. When the concentration exceeds 1% by mass, the other metal tends to be difficult to deposit uniformly on the metal particles. Further, the treatment time in the third step is not particularly limited, but generally about 0.5 to 3 hours is suitably employed.

このような第三の工程の中で起こっている現象は必ずしも明らかではないが、第二の工程によって前記金属粒子に固溶した水素が溶液中で還元剤として働き、前記金属粒子上でイオン状に溶解している他方の金属を還元し、前記金属粒子上に析出させることができると本発明者らは推察する。そして、第三の工程によって前記担体に担持されている金属粒子を前記第一の金属と前記第二の金属との固溶体とした後、前記固溶体からなる金属粒子を担持した担体に、必要に応じて８０〜１５０℃で２〜４８時間程度の乾燥処理を施し、さらに必要に応じて大気中で２００〜５００℃で１〜５時間程度の熱処理を施して排ガス浄化用触媒として用いられる。   Although the phenomenon occurring in the third step is not necessarily clear, hydrogen dissolved in the metal particles in the second step works as a reducing agent in the solution, and is ionized on the metal particles. The present inventors infer that the other metal dissolved in can be reduced and deposited on the metal particles. Then, after the metal particles supported on the carrier in the third step are made into a solid solution of the first metal and the second metal, the carrier on which the metal particles made of the solid solution are supported, if necessary. Then, it is dried at 80 to 150 ° C. for about 2 to 48 hours, and further subjected to heat treatment at 200 to 500 ° C. for about 1 to 5 hours in the atmosphere as needed to be used as an exhaust gas purification catalyst.

上述の本発明の製造方法によって、前記第一の金属と前記第二の金属との固溶体からなる金属粒子の平均一次粒子径が１．５ｎｍ以下であり、且つ、前記固溶体からなる金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であることを特徴とする本発明の排ガス浄化用触媒を得ることが可能となる。すなわち、前記第一の金属と前記第二の金属が均一に固溶した状態で保持されている本発明の排ガス浄化用触媒においては、前記第一の金属と前記第二の金属が十分に均一に混合された状態となっているため、十分に高い窒素酸化物還元性能が発揮され、これを窒素酸化物に接触させることによって十分な量の窒素酸化物を効率よく吸蔵還元させることが可能となる。   By the manufacturing method of the present invention described above, the average primary particle diameter of the metal particles composed of the solid solution of the first metal and the second metal is 1.5 nm or less, and the primary in the metal particles composed of the solid solution. It is possible to obtain the exhaust gas purifying catalyst of the present invention, wherein the standard deviation of the metal composition ratio for each particle is 10% or less. That is, in the exhaust gas purifying catalyst of the present invention in which the first metal and the second metal are held in a uniformly solid solution state, the first metal and the second metal are sufficiently uniform. Since it is in a mixed state, sufficiently high nitrogen oxide reduction performance is exhibited, and it is possible to efficiently store and reduce a sufficient amount of nitrogen oxide by contacting this with nitrogen oxide. Become.

また、上記本発明の製造方法においては、前記固溶体からなる金属粒子を担持した担体に、Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ及びＢａからなる群から選択される少なくとも一種の第三の金属を担持せしめる工程（第四の工程）が更に含まれることがより好ましい。   Further, in the production method of the present invention, at least the carrier selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba is supported on the carrier carrying the metal particles made of the solid solution. More preferably, a step of supporting a kind of third metal (fourth step) is further included.

前記第四の工程は、前記固溶体からなる金属粒子を担持した担体に前記第三の金属を担持させることができればよく、具体的な方法は特に制限されない。このような工程として好適な方法としては、例えば、前記第三の金属がイオン状に溶解している溶液に前記担体を浸し、蒸発乾固を行う方法が挙げられる。このような溶液を作製する際には、前記第三の金属の塩（酢酸塩、炭酸塩、硝酸塩等）、水酸化物等の金属化合物が好適に使用される。また、前記溶液を作製するときに用いる溶媒としては、前記第三の金属がイオン状に溶解すればよく、特に制限されないが、前記担体との親和性の高さから水であることが好ましい。さらに、前記溶液における前記金属の濃度は、０．００１〜２ｍｏｌ／Ｌであることがより好ましい。そして、第四の工程によって前記第三の金属が担持された担体に、必要に応じて大気中で２００〜５００℃で１〜５時間程度の熱処理を施して排ガス浄化用触媒として用いられる。   The fourth step is not particularly limited as long as the third metal can be supported on a carrier supporting metal particles made of the solid solution. As a suitable method for such a step, for example, a method of immersing the carrier in a solution in which the third metal is dissolved in an ionic state and evaporating to dryness can be mentioned. When preparing such a solution, metal compounds such as the third metal salts (acetates, carbonates, nitrates, etc.) and hydroxides are preferably used. The solvent used for preparing the solution is not particularly limited as long as the third metal is dissolved in an ionic form, but is preferably water because of its high affinity with the carrier. Furthermore, the concentration of the metal in the solution is more preferably 0.001 to 2 mol / L. Then, the support on which the third metal is supported in the fourth step is subjected to a heat treatment at 200 to 500 ° C. for about 1 to 5 hours in the atmosphere, if necessary, and used as an exhaust gas purifying catalyst.

なお、本発明の排ガス浄化用触媒の形態は特に制限されず、ハニカム形状のモノリス触媒、ペレット形状のペレット触媒等の形態とすることができる。ここで用いられる基材も特に制限されず、得られる触媒の用途等に応じて適宜選択されるが、ＤＰＦ基材、モノリス状基材、ペレット状基材、プレート状基材等がより好適に採用される。また、このような基材の材料も特に制限されないが、コージェライト、炭化ケイ素、ムライト等のセラミックスからなる基材や、クロム及びアルミニウムを含むステンレススチール等の金属からなる基材が好適に採用される。さらに、このような基材を用いる場合における触媒の製造方法は特に制限されず、例えば、モノリス状基材に担体を担持せしめて担体の粉末からなるコート層を形成した後、前記コート層に前記金属粒子を担持せしめ、その後、前記コート層に前記第三の金属を担持せしめる方法や、あらかじめ前記金属粒子を担持せしめた担体を用い、これをモノリス状基材に担持せしめてコート層を形成した後、前記コート層に前記第三の金属を担持せしめる方法等を採用することができる。   The form of the exhaust gas purifying catalyst of the present invention is not particularly limited, and may be a honeycomb-shaped monolith catalyst, a pellet-shaped pellet catalyst, or the like. The substrate used here is not particularly limited, and is appropriately selected according to the use of the obtained catalyst. A DPF substrate, a monolith substrate, a pellet substrate, a plate substrate, and the like are more preferable. Adopted. Also, the material of such a substrate is not particularly limited, but a substrate made of a ceramic such as cordierite, silicon carbide, mullite, or a substrate made of a metal such as stainless steel including chromium and aluminum is suitably employed. The Furthermore, the method for producing the catalyst in the case of using such a substrate is not particularly limited. For example, after forming a coat layer made of a carrier powder by supporting a carrier on a monolithic substrate, Using a method in which metal particles are supported and then the third metal is supported on the coat layer or a carrier on which the metal particles are previously supported, this is supported on a monolithic substrate to form a coat layer. Thereafter, a method of supporting the third metal on the coat layer can be employed.

以上、本発明の排ガス浄化用触媒の製造方法について説明したが、以下、本発明の排ガス浄化方法について説明する。   Although the method for producing the exhaust gas purifying catalyst of the present invention has been described above, the exhaust gas purifying method of the present invention will be described below.

本発明の排ガス浄化方法は、酸素過剰雰囲気下において、前記本発明の排ガス浄化用触媒に排ガスを接触せしめて前記排ガス中の窒素酸化物を浄化することを特徴とする方法である。   The exhaust gas purification method of the present invention is a method characterized by purifying nitrogen oxides in the exhaust gas by bringing the exhaust gas into contact with the exhaust gas purification catalyst of the present invention in an oxygen-excess atmosphere.

本発明にいう「酸素過剰雰囲気」とは、酸素、窒素酸化物等の酸化性ガスが、Ｈ２，ＣＯ，ＨＣ等の還元性ガスに対して量論的に過剰である雰囲気をいう。本発明においては、このような酸素過剰雰囲気中において窒素酸化物を含有する排ガスを上記本発明の排ガス浄化用触媒に接触せしめる。このように、本発明の排ガス浄化方法においては、本発明の排ガス浄化用触媒を用いるため、窒素酸化物を十分に浄化することが可能である。そのため、本発明の排ガス浄化方法は、例えば、自動車の内燃機関等から排出される排ガスを浄化するための方法に採用することができる。 The “oxygen-excess atmosphere” in the present invention refers to an atmosphere in which an oxidizing gas such as oxygen or nitrogen oxide is quantitatively excessive with respect to a reducing gas such as H 2 , CO, or HC. In the present invention, the exhaust gas containing nitrogen oxides is brought into contact with the exhaust gas purifying catalyst of the present invention in such an oxygen-excess atmosphere. Thus, in the exhaust gas purification method of the present invention, since the exhaust gas purification catalyst of the present invention is used, nitrogen oxides can be sufficiently purified. Therefore, the exhaust gas purification method of the present invention can be employed in a method for purifying exhaust gas discharged from, for example, an internal combustion engine of an automobile.

以下、実施例及び比較例に基づいて本発明をより具体的に説明するが、本発明は以下の実施例に限定されるものではない。   EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

（実施例１）
先ず、０．０３８ｇのＰｄ（ＮＯ３）２を１００ｇの水に溶解した水溶液（Ｐｄ濃度：０．０１７５質量％）にアルミナ粉末（平均二次粒子径：８μｍ、比表面積：２００ｍ２／ｇ）を１０ｇ添加し、１時間撹拌した後、粉末を取り出して大気中で１１０℃２４時間の乾燥を行い、パラジウム粒子が担持されたアルミナ粉末（Ｐｄ／Ａｌ２Ｏ３粉末）を得た（第一の工程）。 Example 1
First, alumina powder (average secondary particle size: 8 μm, specific surface area: 200 m 2 / g) in an aqueous solution (Pd concentration: 0.0175% by mass) in which 0.038 g of Pd (NO 3 ) 2 was dissolved in 100 g of water. After stirring for 1 hour, the powder was taken out and dried in the atmosphere at 110 ° C. for 24 hours to obtain alumina powder (Pd / Al 2 O 3 powder) carrying palladium particles (first). Process).

次に、Ｐｄ／Ａｌ２Ｏ３粉末を、水素濃度が５容量％の雰囲気（バランスガスは窒素）中に配置し、４００℃３時間の水素化処理を施し、パラジウム粒子に水素が固溶したアルミナ粉末（粉末Ａ）を得た（第二の工程）。 Next, the Pd / Al 2 O 3 powder was placed in an atmosphere having a hydrogen concentration of 5% by volume (balance gas was nitrogen) and subjected to hydrogenation treatment at 400 ° C. for 3 hours, so that hydrogen was dissolved in palladium particles. An alumina powder (powder A) was obtained (second step).

続いて、粉末Ａを、水素濃度が５容量％の雰囲気に維持された容器中から、大気中に晒すことなく直接、０．０７０ｇのＰｔ（ＮＯ２）２（ＮＨ３）２を１００ｇの水に溶解した水溶液（Ｐｔ濃度：０．０４２５質量％）中に投入し、１時間撹拌した後、粉末を取り出して大気中で１１０℃２４時間の乾燥を行い、さらに大気中で３００℃３時間の熱処理を施し、パラジウムと白金との固溶体からなる金属粒子が担持された（粉末Ｂ）を得た（第三の工程）。 Subsequently, 0.070 g of Pt (NO 2 ) 2 (NH 3 ) 2 was directly added to 100 g of water from a container maintained in an atmosphere having a hydrogen concentration of 5% by volume without being exposed to the atmosphere. The solution was poured into an aqueous solution (Pt concentration: 0.0425% by mass) dissolved in 1 and stirred for 1 hour, then the powder was taken out and dried in the atmosphere at 110 ° C for 24 hours, and further in the atmosphere at 300 ° C for 3 hours. Heat treatment was performed to obtain (powder B) on which metal particles made of a solid solution of palladium and platinum were supported (third step).

さらに、粉末Ｂを、（ＣＨ３ＣＯＯ）２Ｂａ、ＣＨ３ＣＯＯＫ及びＣＨ３ＣＯＯＬｉを含む水溶液（Ｂａ濃度：０．１ｍｏｌ／Ｌ、Ｋ濃度：０．１ｍｏｌ／Ｌ、Ｌｉ濃度：０．２ｍｏｌ／Ｌ）に浸した後、粉末を取り出して大気中で１１０℃２４時間の乾燥を行って蒸発乾固せしめ、さらに大気中で３００℃３時間の熱処理を施して排ガス浄化用触媒を得た（第四の工程）。 Furthermore, the powder B was converted into an aqueous solution containing (CH 3 COO) 2 Ba, CH 3 COOK and CH 3 COOLi (Ba concentration: 0.1 mol / L, K concentration: 0.1 mol / L, Li concentration: 0.2 mol / After soaking in (L), the powder was taken out, dried in the atmosphere at 110 ° C. for 24 hours to evaporate to dryness, and further subjected to a heat treatment in the atmosphere at 300 ° C. for 3 hours to obtain an exhaust gas purification catalyst (No. 1). Fourth step).

なお、得られた触媒におけるパラジウムと白金との固溶体からなる金属粒子の担持量はアルミナ粉末１００質量部に対して０．６０質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれアルミナ粉末１００質量部に対して０．１ｍｏｌ／１００ｇ，０．１ｍｏｌ／１００ｇ，０．２ｍｏｌ／１００ｇであった。   The supported amount of metal particles composed of a solid solution of palladium and platinum in the obtained catalyst was 0.60 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum was (Pd) 3 atoms. %: (Pt) 4 atomic%. The supported amounts of Ba, K, and Li in the obtained catalyst were 0.1 mol / 100 g, 0.1 mol / 100 g, and 0.2 mol / 100 g, respectively, with respect to 100 parts by mass of the alumina powder.

（比較例１）
先ず、０．０３８ｇのＰｄ（ＮＯ３）２と０．０６８ｇのＰｔ（ＮＯ２）２（ＮＨ３）３とを１００ｇの水に溶解した水溶液（Ｐｄ濃度：０．０１７５質量％、Ｐｔ濃度：０．０４２５質量％）にアルミナ粉末（平均二次粒子径：８μｍ、比表面積：２００ｍ２／ｇ）を１０ｇ添加し、１時間撹拌した後、粉末を取り出して大気中で１１０℃２４時間の乾燥を行い、パラジウムと白金とが共含浸により担持されたアルミナ粉末を得た。次に、得られた粉末に対して、実施例１における第二の工程と第三の工程は施さずに、第四の工程を施して排ガス浄化用触媒を得た。 (Comparative Example 1)
First, an aqueous solution (Pd concentration: 0.0175 mass%, Pt concentration: 0.038 g of Pd (NO 3 ) 2 and 0.068 g of Pt (NO 2 ) 2 (NH 3 ) 3 dissolved in 100 g of water). 0.0425% by mass) 10 g of alumina powder (average secondary particle size: 8 μm, specific surface area: 200 m 2 / g) was added and stirred for 1 hour, then the powder was taken out and dried at 110 ° C. for 24 hours in the atmosphere. Thus, an alumina powder in which palladium and platinum were supported by co-impregnation was obtained. Next, the second step and the third step in Example 1 were not performed on the obtained powder, and a fourth step was performed to obtain an exhaust gas purifying catalyst.

なお、得られた触媒におけるパラジウムと白金との合計担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The total supported amount of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atomic%: (Pt) It was 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

（比較例２）
第二の工程における水素化処理の後に粉末Ａが配置された容器内に窒素パージを行ったため、第三の工程において粉末Ａが窒素雰囲気に曝露された後に前記水溶液中に投入されるようにしたこと以外は実施例１と同様の方法で排ガス浄化用触媒を得た。 (Comparative Example 2)
Since the nitrogen purge was performed in the container in which the powder A was disposed after the hydrogenation treatment in the second step, the powder A was put in the aqueous solution after being exposed to the nitrogen atmosphere in the third step. Except for this, an exhaust gas purifying catalyst was obtained in the same manner as in Example 1.

なお、得られた触媒におけるパラジウムと白金との固溶体からなる金属粒子の担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The supported amount of metal particles composed of a solid solution of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atoms. %: (Pt) 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

＜排ガス浄化用触媒（実施例１及び比較例１〜２）の性能試験１＞
［ＴＥＭ−ＥＤＸ分析］
実施例１及び比較例１〜２で得られた排ガス浄化用触媒について、前述の方法により、ＴＥＭ−ＥＤＸ分析を行った。なお、このようなＴＥＭ−ＥＤＸ分析には、日本電子製の商品名「ＪＥＭ−２０１０ＦＥＦ」を測定装置として用いた。 <Performance Test 1 of Exhaust Gas Purification Catalyst (Example 1 and Comparative Examples 1 and 2)>
[TEM-EDX analysis]
The exhaust gas purifying catalysts obtained in Example 1 and Comparative Examples 1 and 2 were subjected to TEM-EDX analysis by the method described above. For such TEM-EDX analysis, a trade name “JEM-2010FEF” manufactured by JEOL Ltd. was used as a measuring device.

このような測定の結果として、実施例１で得られた排ガス浄化用触媒の透過型電子顕微鏡（ＴＥＭ）写真を図１〜３に示し、比較例１で得られた排ガス浄化用触媒の透過型電子顕微鏡（ＴＥＭ）写真を図４〜６に示す。なお、図１〜６上の００１〜０１５で示す×印は、ＥＤＸ分析の際の測定点である。また、実施例１で得られた排ガス浄化用触媒の表面上の測定点００１〜００５におけるエネルギー分散型蛍光Ｘ線スペクトルを図７に示し、比較例１で得られた排ガス浄化用触媒の表面上の測定点００１〜００５におけるエネルギー分散型蛍光Ｘ線スペクトルを図８に示す。   As a result of such measurement, transmission electron microscope (TEM) photographs of the exhaust gas purification catalyst obtained in Example 1 are shown in FIGS. 1 to 3, and the transmission type of the exhaust gas purification catalyst obtained in Comparative Example 1 is shown. Electron microscope (TEM) photographs are shown in FIGS. In addition, the x mark shown by 001-015 on FIGS. 1-6 is a measurement point in the case of EDX analysis. Moreover, the energy dispersive fluorescent X-ray spectrum at the measurement points 001 to 005 on the surface of the exhaust gas purifying catalyst obtained in Example 1 is shown in FIG. 7, and on the surface of the exhaust gas purifying catalyst obtained in Comparative Example 1. The energy dispersive X-ray fluorescence spectrum at the measurement points 001 to 005 is shown in FIG.

このような測定結果に基づいて、実施例１及び比較例１〜２で得られた排ガス浄化用触媒における金属粒子の一次粒子毎の金属組成比（ＰｔとＰｄの組成比）の標準偏差を、前述の方法により求めた。得られた結果を表１に示す。   Based on such measurement results, the standard deviation of the metal composition ratio (composition ratio of Pt and Pd) for each primary particle of the metal particles in the exhaust gas purifying catalyst obtained in Example 1 and Comparative Examples 1 and 2 is determined. It was determined by the method described above. The obtained results are shown in Table 1.

表１に示す結果からも明らかなように、本発明の排ガス浄化用触媒（実施例１）においては、担持された酸化物複合体の表面上の測定点におけるＴＥＭ−ＥＤＸから求められる第一の金属（Ｐｔ）のピーク面積と第二の金属（Ｐｄ）のピーク面積との和に対する第一の金属のピーク面積の比（［第一の金属のピーク面積］／［第一の金属のピーク面積と第二の金属のピーク面積の和］）の分布の標準偏差は１０％以下であることが確認された。このような結果から、本発明の排ガス浄化用触媒においては、ＰｔとＰｄとが十分に均一に固溶された金属粒子が金属酸化物担体上に担持されていることが確認された。これに対して、比較のための排ガス浄化用触媒（比較例１及び比較例２）においては、前記標準偏差が１０％を超えた値となっており、ＰｔとＰｄが均一に固溶されていないことが確認された。   As is clear from the results shown in Table 1, in the exhaust gas purifying catalyst of the present invention (Example 1), the first obtained from TEM-EDX at the measurement point on the surface of the supported oxide composite. Ratio of the peak area of the first metal to the sum of the peak area of the metal (Pt) and the peak area of the second metal (Pd) ([peak area of the first metal] / [peak area of the first metal] And the standard deviation of the distribution of the peak area of the second metal]) was confirmed to be 10% or less. From these results, it was confirmed that in the exhaust gas purifying catalyst of the present invention, metal particles in which Pt and Pd are sufficiently uniformly dissolved are supported on the metal oxide support. On the other hand, in the exhaust gas purification catalysts for comparison (Comparative Examples 1 and 2), the standard deviation is a value exceeding 10%, and Pt and Pd are uniformly dissolved. Not confirmed.

［窒素酸化物浄化試験１］
実施例１及び比較例１で得られた排ガス浄化用触媒１．０ｇを試験容器内に配置し、３００℃の温度条件下において表２に示す組成のリッチガス及びリーンガスをリーン／リッチ＝４０秒／５秒の間隔で変動させながら流通させ、定常状態における窒素酸化物浄化率を測定した。窒素酸化物浄化率は、各触媒において、それぞれの触媒に接触する前後のガス中に含有される窒素酸化物の濃度を測定し、その窒素酸化物濃度の値に基づいて求めた。得られた結果を図９に示す。 [Nitrogen oxide purification test 1]
1.0 g of the exhaust gas purifying catalyst obtained in Example 1 and Comparative Example 1 was placed in a test container, and the rich gas and the lean gas having the composition shown in Table 2 under a temperature condition of 300 ° C. were set to lean / rich = 40 seconds / The nitrogen oxide purification rate in a steady state was measured by changing the flow rate at intervals of 5 seconds. The nitrogen oxide purification rate was determined on the basis of the value of the nitrogen oxide concentration obtained by measuring the concentration of nitrogen oxide contained in the gas before and after contacting each catalyst. The obtained results are shown in FIG.

図９に示した結果から明らかなように、本発明の排ガス浄化用触媒（実施例１）は、優れた窒素酸化物浄化率を示した。これに対して、本発明にかかる排ガス浄化用触媒を用いなかった場合（比較例１）においては、窒素酸化物浄化率が低いものとなっていた。このような結果から、本発明の排ガス浄化用触媒においては、得られる金属粒子においてＰｔとＰｄとが十分に均一に固溶された状態で金属酸化物担体に担持されているため、高い窒素酸化物浄化性能を発揮できるということが確認できた。   As is clear from the results shown in FIG. 9, the exhaust gas purifying catalyst (Example 1) of the present invention showed an excellent nitrogen oxide purification rate. On the other hand, when the exhaust gas purifying catalyst according to the present invention was not used (Comparative Example 1), the nitrogen oxide purification rate was low. From these results, in the exhaust gas purifying catalyst of the present invention, since the metal particles obtained are supported on the metal oxide support in a state where Pt and Pd are sufficiently uniformly dissolved, high nitrogen oxidation is achieved. It was confirmed that the product purification performance can be demonstrated.

（実施例２）
第二の工程における水素濃度を１容量％にしたこと以外は実施例１と同様の方法で排ガス浄化用触媒を得た。 (Example 2)
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the hydrogen concentration in the second step was 1% by volume.

なお、得られた触媒におけるパラジウムと白金との固溶体からなる金属粒子の担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The supported amount of metal particles composed of a solid solution of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atoms. %: (Pt) 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

（実施例３）
第二の工程における水素化処理の温度を１００℃にしたこと以外は実施例１と同様の方法で排ガス浄化用触媒を得た。 (Example 3)
Exhaust gas purification catalyst was obtained in the same manner as in Example 1 except that the temperature of the hydrogenation treatment in the second step was 100 ° C.

なお、得られた触媒におけるパラジウムと白金との固溶体からなる金属粒子の担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The supported amount of metal particles composed of a solid solution of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atoms. %: (Pt) 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

（実施例４）
第二の工程における水素化処理の温度を２００℃にしたこと以外は実施例１と同様の方法で排ガス浄化用触媒を得た。 (Example 4)
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that the temperature of the hydrogenation treatment in the second step was 200 ° C.

なお、得られた触媒におけるパラジウムと白金との固溶体からなる金属粒子の担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The supported amount of metal particles composed of a solid solution of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atoms. %: (Pt) 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

（実施例５）
第二の工程における水素化処理の温度を３００℃にしたこと以外は実施例１と同様の方法で排ガス浄化用触媒を得た。 (Example 5)
An exhaust gas purifying catalyst was obtained in the same manner as in Example 1 except that the temperature of the hydrogenation treatment in the second step was 300 ° C.

なお、得られた触媒におけるパラジウムと白金との固溶体からなる金属粒子の担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The supported amount of metal particles composed of a solid solution of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atoms. %: (Pt) 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

＜排ガス浄化用触媒（実施例１〜５及び比較例２）の性能試験２＞
実施例１〜５及び比較例２で得られた排ガス浄化用触媒を用いて３５０℃で試験を行ったこと以外は前述の窒素酸化物浄化試験１と同様の方法を採用して窒素酸化物浄化率を測定した。得られた結果を図１０に示す。 <Performance Test 2 of Exhaust Gas Purification Catalyst (Examples 1 to 5 and Comparative Example 2)>
Nitrogen oxide purification by adopting the same method as the above-mentioned nitrogen oxide purification test 1 except that the test was performed at 350 ° C. using the exhaust gas purification catalysts obtained in Examples 1 to 5 and Comparative Example 2. The rate was measured. The obtained result is shown in FIG.

図１０に示した結果から明らかなように、本発明の排ガス浄化用触媒（実施例１〜５）は、優れた窒素酸化物浄化率を示した。これに対して、本発明にかかる排ガス浄化用触媒を用いなかった場合（比較例２）においては、窒素酸化物浄化率が低いものとなっていた。このような結果から、本発明の排ガス浄化用触媒においては、得られる金属粒子においてＰｔとＰｄとが十分に均一に固溶された状態で金属酸化物担体に担持されているため、高い窒素酸化物浄化性能を発揮できるということが確認できた。   As is clear from the results shown in FIG. 10, the exhaust gas purifying catalysts (Examples 1 to 5) of the present invention exhibited an excellent nitrogen oxide purification rate. On the other hand, when the exhaust gas purifying catalyst according to the present invention was not used (Comparative Example 2), the nitrogen oxide purification rate was low. From these results, in the exhaust gas purifying catalyst of the present invention, since the metal particles obtained are supported on the metal oxide support in a state where Pt and Pd are sufficiently uniformly dissolved, high nitrogen oxidation is achieved. It was confirmed that the product purification performance can be demonstrated.

（比較例３）
先ず、０．０６ｇのＰｔＰｄコアシェル−ＰＶＰコロイド（粒径：約２ｎｍ）が１００ｇの水に分散されている分散液（Ｐｄ濃度：０．０１７５質量％、Ｐｔ濃度：０．０４２５質量％）にアルミナ粉末（平均二次粒子径：８μｍ、比表面積：２００ｍ２／ｇ）を１０ｇ添加した後、粉末を取り出して大気中で１１０℃５時間の乾燥を行って蒸発乾固せしめ、パラジウムと白金とが担持されたアルミナ粉末を得た。次に、得られた粉末に対して、実施例１における第二の工程と第三の工程は施さずに、第四の工程を施して排ガス浄化用触媒を得た。 (Comparative Example 3)
First, alumina was added to a dispersion (Pd concentration: 0.0175 mass%, Pt concentration: 0.0425 mass%) in which 0.06 g of PtPd core-shell-PVP colloid (particle size: about 2 nm) was dispersed in 100 g of water. After adding 10 g of powder (average secondary particle size: 8 μm, specific surface area: 200 m 2 / g), the powder was taken out and dried in the atmosphere at 110 ° C. for 5 hours to evaporate to dryness. A supported alumina powder was obtained. Next, the second step and the third step in Example 1 were not performed on the obtained powder, and a fourth step was performed to obtain an exhaust gas purifying catalyst.

なお、得られた触媒におけるパラジウムと白金との合計担持量はアルミナ粉末１００質量部に対して０．６質量部であり、パラジウムと白金との組成比は（Ｐｄ）３原子％：（Ｐｔ）４原子％であった。また、得られた触媒におけるＢａ，Ｋ，Ｌｉの担持量はそれぞれ実施例１で得られたものと同様であった。   The total supported amount of palladium and platinum in the obtained catalyst is 0.6 parts by mass with respect to 100 parts by mass of the alumina powder, and the composition ratio of palladium and platinum is (Pd) 3 atomic%: (Pt) It was 4 atomic%. Further, the supported amounts of Ba, K and Li in the obtained catalyst were the same as those obtained in Example 1, respectively.

＜排ガス浄化用触媒（実施例１〜５及び比較例３）の平均一次粒子径測定＞
実施例１〜５及び比較例３で得られた排ガス浄化用触媒における金属粒子の平均一次粒子径をＣＯ化学吸着法によって求めた。得られた結果を図１１に示す。 <Measurement of average primary particle diameter of exhaust gas purifying catalysts (Examples 1 to 5 and Comparative Example 3)>
The average primary particle diameter of the metal particles in the exhaust gas purifying catalysts obtained in Examples 1 to 5 and Comparative Example 3 was determined by a CO chemical adsorption method. The obtained results are shown in FIG.

図１１に示した結果から明らかなように、本発明の排ガス浄化用触媒（実施例１〜５）に担持された金属粒子の平均一次粒子径は１．５ｎｍと十分に小さかった。これに対して、本発明にかかる排ガス浄化用触媒を用いなかった場合（比較例３）においては、金属一次粒子径が１．５ｎｍより大きいことが確認された。このような結果から、本発明の排ガス浄化用触媒においては、ＰｔとＰｄとの固溶体からなる金属粒子の平均一次粒子径が十分に小さいということが確認できた。   As is clear from the results shown in FIG. 11, the average primary particle diameter of the metal particles carried on the exhaust gas purifying catalysts (Examples 1 to 5) of the present invention was sufficiently small at 1.5 nm. On the other hand, when the exhaust gas purifying catalyst according to the present invention was not used (Comparative Example 3), it was confirmed that the metal primary particle diameter was larger than 1.5 nm. From these results, it was confirmed that in the exhaust gas purifying catalyst of the present invention, the average primary particle diameter of the metal particles made of a solid solution of Pt and Pd was sufficiently small.

以上説明したように、本発明によれば、第一の金属と第二の金属が均一に固溶した状態で金属酸化物担体に担持されており、自動車等の排ガスに含まれる窒素酸化物を十分に還元する能力を有する排ガス浄化用触媒、及びその製造方法、ならびにそれを用いた排ガス浄化方法を提供することが可能となる。   As described above, according to the present invention, the first metal and the second metal are supported on the metal oxide support in a state where the first metal and the second metal are uniformly dissolved, and the nitrogen oxide contained in the exhaust gas of an automobile or the like is removed. It is possible to provide an exhaust gas purification catalyst having a sufficient ability to reduce, a method for producing the same, and an exhaust gas purification method using the same.

Claims (4)

金属酸化物からなる担体と、前記担体に担持された金属粒子とを備える排ガス浄化用触媒であって、
前記金属粒子が、Ｐｔである第一の金属と、Ｐｄである第二の金属との固溶体からなり、
前記金属粒子の平均一次粒子径が１．５ｎｍ以下であり、
前記金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であり、且つ、
前記担体に、Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ及びＢａからなる群から選択される少なくとも一種の第三の金属が更に担持されていること、
を特徴とする排ガス浄化用触媒。 An exhaust gas purifying catalyst comprising a support made of a metal oxide and metal particles supported on the support,
Wherein the metal particles are made of a solid solution of the first metal is P t, the second metal is P d,
The average primary particle diameter of the metal particles is 1.5 nm or less,
The standard deviation of the metal composition ratio for each primary particle in the metal particles is 10% or less, and
The carrier further carries at least one third metal selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba,
An exhaust gas purifying catalyst characterized by. Ｐｔである第一の金属と、Ｐｄである第二の金属とのうちいずれか一方の金属からなる粒子を金属酸化物からなる担体に担持せしめる工程と、
前記金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中で５０℃以上に加熱して前記金属粒子に水素を固溶せしめる工程と、
前記水素が固溶した金属粒子を担持した担体を、水素濃度が０．５容量％以上の雰囲気中に維持しつつ前記第一の金属と前記第二の金属とのうち他方の金属のイオンを含有する溶液中に浸漬せしめ、前記金属粒子に固溶している水素により前記他方の金属を還元せしめることにより、前記第一の金属と前記第二の金属との固溶体からなる金属粒子を前記担体に担持せしめる工程と、
前記固溶体からなる金属粒子を担持した担体に、Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，Ｂｅ，Ｍｇ，Ｃａ，Ｓｒ及びＢａからなる群から選択される少なくとも一種の第三の金属を担持せしめて排ガス浄化用触媒を得る工程と、
を含むことを特徴とする排ガス浄化用触媒の製造方法。 A step of supporting particles made of any one of a first metal being Pt and a second metal being Pd on a carrier made of a metal oxide;
Heating the support carrying the metal particles to 50 ° C. or more in an atmosphere having a hydrogen concentration of 0.5% by volume or more to cause hydrogen to be dissolved in the metal particles;
While maintaining the carrier carrying the metal particles in which hydrogen is dissolved in an atmosphere having a hydrogen concentration of 0.5% by volume or more, ions of the other metal out of the first metal and the second metal A metal particle comprising the solid solution of the first metal and the second metal is obtained by immersing it in a solution containing it and reducing the other metal with hydrogen dissolved in the metal particle. A process of supporting the
Exhaust gas by supporting at least one third metal selected from the group consisting of Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr and Ba on a carrier supporting metal particles made of the solid solution. Obtaining a purification catalyst;
A method for producing an exhaust gas purifying catalyst, comprising: 前記固溶体からなる金属粒子の平均一次粒子径が１．５ｎｍ以下であり、且つ、前記固溶体からなる金属粒子における一次粒子毎の金属組成比の標準偏差が１０％以下であることを特徴とする請求項２に記載の排ガス浄化用触媒の製造方法。 The average primary particle diameter of the metal particles made of the solid solution is 1.5 nm or less, and the standard deviation of the metal composition ratio for each primary particle in the metal particles made of the solid solution is 10% or less. Item 3. A method for producing an exhaust gas purifying catalyst according to Item 2 . 酸素過剰雰囲気下において、請求項１に記載の排ガス浄化用触媒に排ガスを接触せしめて前記排ガス中の窒素酸化物を浄化することを特徴とする排ガス浄化方法。 In an oxygen-rich atmosphere, the exhaust gas purification method, characterized in that purifies nitrogen oxides in the flue contacted the exhaust the exhaust gas purifying catalyst according to claim 1.
JP2009038843A 2009-02-23 2009-02-23 Exhaust gas purification catalyst and method for producing the same Expired - Fee Related JP5491745B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2009038843A JP5491745B2 (en) 2009-02-23 2009-02-23 Exhaust gas purification catalyst and method for producing the same
PCT/JP2010/052909 WO2010095761A2 (en) 2009-02-23 2010-02-18 Catalyst for purification of exhaust gas and method of manufacturing the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2009038843A JP5491745B2 (en) 2009-02-23 2009-02-23 Exhaust gas purification catalyst and method for producing the same

Publications (2)

Publication Number Publication Date
JP2010194384A JP2010194384A (en) 2010-09-09
JP5491745B2 true JP5491745B2 (en) 2014-05-14

Family

ID=42341609

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2009038843A Expired - Fee Related JP5491745B2 (en) 2009-02-23 2009-02-23 Exhaust gas purification catalyst and method for producing the same

Country Status (2)

Country Link
JP (1) JP5491745B2 (en)
WO (1) WO2010095761A2 (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9115621B2 (en) 2011-03-04 2015-08-25 Toyota Jidosha Kabushiki Kaisha Metal particles, exhaust gas purifying catalyst comprising metal particles, and methods for producing them
JP5533782B2 (en) * 2011-05-19 2014-06-25 トヨタ自動車株式会社 Exhaust gas purification catalyst and method for producing the same
WO2013005345A1 (en) * 2011-07-07 2013-01-10 Toyota Jidosha Kabushiki Kaisha NOx PURIFICATION CATALYST AND METHOD OF PRODUCING THE SAME
US9114384B2 (en) 2011-08-23 2015-08-25 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification catalyst and method for producing it
JP2013220377A (en) * 2012-04-16 2013-10-28 Cataler Corp Exhaust gas purification catalyst
JP6107683B2 (en) * 2014-01-27 2017-04-05 トヨタ自動車株式会社 Method for producing exhaust gas purification catalyst
JP6444265B2 (en) * 2014-06-02 2018-12-26 株式会社豊田中央研究所 Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification method using the same
JP6508090B2 (en) * 2016-03-03 2019-05-08 トヨタ自動車株式会社 Exhaust gas purification catalyst

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2546078B1 (en) * 1983-05-19 1987-05-07 Pro Catalyse PROCESS FOR THE MANUFACTURE OF CATALYSTS FOR THE TREATMENT OF EXHAUST GASES FROM INTERNAL COMBUSTION ENGINES
JPH07157806A (en) * 1993-12-02 1995-06-20 Tanaka Kikinzoku Kogyo Kk Production of multiple powder
JP3903598B2 (en) 1997-09-24 2007-04-11 トヨタ自動車株式会社 Exhaust gas purification catalyst and method for producing the same
JP4346215B2 (en) 2000-06-16 2009-10-21 トヨタ自動車株式会社 Method for producing exhaust gas purification catalyst
US6534661B1 (en) * 2000-12-28 2003-03-18 Hydrocarbon Technologies, Inc. Integrated process and dual-function catalyst for olefin epoxidation
JP4195319B2 (en) 2003-03-11 2008-12-10 トヨタ自動車株式会社 Catalysts produced using multi-component metal colloids
JP4199691B2 (en) * 2004-03-25 2008-12-17 田中貴金属工業株式会社 catalyst
US7507495B2 (en) * 2004-12-22 2009-03-24 Brookhaven Science Associates, Llc Hydrogen absorption induced metal deposition on palladium and palladium-alloy particles
US7601668B2 (en) * 2006-09-29 2009-10-13 Headwaters Technology Innovation, Llc Methods for manufacturing bi-metallic catalysts having a controlled crystal face exposure
KR20080047950A (en) * 2006-11-27 2008-05-30 나노스텔라 인코포레이티드 Engine exhaust catalysts containing palladium-gold
JP5116377B2 (en) * 2007-06-22 2013-01-09 旭化成株式会社 Exhaust NOx purification method
DE102008042243A1 (en) * 2008-09-22 2010-04-01 Robert Bosch Gmbh Catalytically active coating for use in catalytic converter for treating internal-combustion engine exhaust gases, comprises multiple different zones, where former zone is oxidation zone for nitrogenous compounds

Also Published As

Publication number Publication date
WO2010095761A3 (en) 2011-08-25
JP2010194384A (en) 2010-09-09
WO2010095761A2 (en) 2010-08-26

Similar Documents

Publication Publication Date Title
JP5491745B2 (en) Exhaust gas purification catalyst and method for producing the same
EP1839749B1 (en) Catalyst, exhaust gas clarifying catalyst, and method for producing catalyst
JP6415738B2 (en) Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification apparatus including the catalyst
WO1999032223A1 (en) Exhaust gas cleaning catalyst, process for producing the same, and exhaust gas cleaning method
US10828602B2 (en) Exhaust gas purifying catalyst and method for producing same, and exhaust gas purification device using same
JP2015073936A (en) Method of producing catalyst
WO2011052676A1 (en) Exhaust cleaner for internal combustion engine
JP5975104B2 (en) Exhaust gas purification catalyst and method for producing the same
JP4730947B2 (en) Method for regenerating exhaust gas purification catalyst
JP5290062B2 (en) Exhaust gas purification catalyst
JP3441267B2 (en) Catalyst production method
JP2020131111A (en) Exhaust gas purifying catalyst
JP4775953B2 (en) Exhaust gas purification catalyst and regeneration method thereof
JP5299603B2 (en) Oxide complex precursor aqueous solution, oxide complex production method, oxide complex, exhaust gas purification catalyst including the oxide complex, and exhaust gas purification method using the exhaust gas purification catalyst
JP7099304B2 (en) Exhaust gas purification catalyst
JP2013198888A (en) Carrier for exhaust emission control catalyst, nitrogen oxide removal catalyst obtained by using the same, and methods for producing them
JP6011779B2 (en) Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification method using the same
JP4697796B2 (en) Exhaust gas purification catalyst and regeneration method thereof
JP2020131086A (en) Exhaust gas purifying catalyst
JP6108289B2 (en) CO oxidation catalyst and method for producing the same
JP6264639B2 (en) N2O decomposition catalyst and N2O-containing gas decomposition method using the same
JP6096818B2 (en) Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification method using the same
JP4697506B2 (en) Exhaust gas purification catalyst and method for producing the same
JP2017185438A (en) Catalyst for purifying exhaust gas
JP2011092852A (en) Composite monolithic catalyst for cleaning exhaust gas

Legal Events

Date Code Title Description
RD02 Notification of acceptance of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7422

Effective date: 20101105

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A821

Effective date: 20101105

A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20111012

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20130607

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20130705

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20131001

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20131114

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20140131

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20140228

R150 Certificate of patent or registration of utility model

Ref document number: 5491745

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

LAPS Cancellation because of no payment of annual fees