JP4971918B2 - Exhaust gas purification catalyst and method for producing the same - Google Patents
Exhaust gas purification catalyst and method for producing the same Download PDFInfo
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- JP4971918B2 JP4971918B2 JP2007237100A JP2007237100A JP4971918B2 JP 4971918 B2 JP4971918 B2 JP 4971918B2 JP 2007237100 A JP2007237100 A JP 2007237100A JP 2007237100 A JP2007237100 A JP 2007237100A JP 4971918 B2 JP4971918 B2 JP 4971918B2
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- Prior art keywords
- compound
- noble metal
- exhaust gas
- metal particles
- gas purifying
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- 239000003054 catalyst Substances 0.000 title claims description 178
- 238000000746 purification Methods 0.000 title claims description 27
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 229910000510 noble metal Inorganic materials 0.000 claims description 191
- 239000002923 metal particle Substances 0.000 claims description 142
- 150000001875 compounds Chemical class 0.000 claims description 122
- 239000000843 powder Substances 0.000 claims description 106
- 239000002245 particle Substances 0.000 claims description 53
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 30
- 239000000758 substrate Substances 0.000 claims description 29
- 230000002776 aggregation Effects 0.000 claims description 25
- 239000011148 porous material Substances 0.000 claims description 25
- 238000004220 aggregation Methods 0.000 claims description 24
- 239000002131 composite material Substances 0.000 claims description 21
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 21
- 239000010970 precious metal Substances 0.000 claims description 20
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 17
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 17
- 229910052783 alkali metal Inorganic materials 0.000 claims description 14
- 150000001340 alkali metals Chemical class 0.000 claims description 14
- 239000011163 secondary particle Substances 0.000 claims description 13
- 229910052763 palladium Inorganic materials 0.000 claims description 11
- 229910052697 platinum Inorganic materials 0.000 claims description 10
- 229910052788 barium Inorganic materials 0.000 claims description 9
- 229910052746 lanthanum Inorganic materials 0.000 claims description 9
- 238000001179 sorption measurement Methods 0.000 claims description 9
- 229910052726 zirconium Inorganic materials 0.000 claims description 9
- 229910052684 Cerium Inorganic materials 0.000 claims description 8
- 229910052703 rhodium Inorganic materials 0.000 claims description 7
- 238000005245 sintering Methods 0.000 claims description 7
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 229910052779 Neodymium Inorganic materials 0.000 claims description 3
- 238000004458 analytical method Methods 0.000 claims description 3
- 229910052792 caesium Inorganic materials 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 229910052700 potassium Inorganic materials 0.000 claims description 3
- 229910052701 rubidium Inorganic materials 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 229910052712 strontium Inorganic materials 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 85
- 229940125782 compound 2 Drugs 0.000 description 83
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 43
- 239000002002 slurry Substances 0.000 description 39
- 229940126214 compound 3 Drugs 0.000 description 36
- 230000000694 effects Effects 0.000 description 36
- 229910001593 boehmite Inorganic materials 0.000 description 35
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 35
- 229910002651 NO3 Inorganic materials 0.000 description 34
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 34
- 230000000052 comparative effect Effects 0.000 description 31
- 238000012360 testing method Methods 0.000 description 26
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 20
- 238000000034 method Methods 0.000 description 20
- 239000001301 oxygen Substances 0.000 description 20
- 229910052760 oxygen Inorganic materials 0.000 description 20
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 16
- 230000003197 catalytic effect Effects 0.000 description 16
- 239000000463 material Substances 0.000 description 16
- 238000002360 preparation method Methods 0.000 description 15
- 239000010948 rhodium Substances 0.000 description 15
- 239000002105 nanoparticle Substances 0.000 description 11
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 10
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 10
- 239000000203 mixture Substances 0.000 description 10
- 238000010298 pulverizing process Methods 0.000 description 9
- 239000004215 Carbon black (E152) Substances 0.000 description 8
- 229910052878 cordierite Inorganic materials 0.000 description 8
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 8
- 239000010419 fine particle Substances 0.000 description 8
- 229930195733 hydrocarbon Natural products 0.000 description 8
- 150000002430 hydrocarbons Chemical class 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 239000007864 aqueous solution Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 239000011246 composite particle Substances 0.000 description 7
- 239000013078 crystal Substances 0.000 description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 230000004913 activation Effects 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 238000013508 migration Methods 0.000 description 5
- 230000005012 migration Effects 0.000 description 5
- 239000002243 precursor Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 239000011800 void material Substances 0.000 description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- UEGPKNKPLBYCNK-UHFFFAOYSA-L magnesium acetate Chemical compound [Mg+2].CC([O-])=O.CC([O-])=O UEGPKNKPLBYCNK-UHFFFAOYSA-L 0.000 description 4
- 229910017604 nitric acid Inorganic materials 0.000 description 4
- 239000002585 base Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 150000003623 transition metal compounds Chemical class 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 229910004625 Ce—Zr Inorganic materials 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 2
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- UJVRJBAUJYZFIX-UHFFFAOYSA-N nitric acid;oxozirconium Chemical compound [Zr]=O.O[N+]([O-])=O.O[N+]([O-])=O UJVRJBAUJYZFIX-UHFFFAOYSA-N 0.000 description 2
- 230000000607 poisoning effect Effects 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- -1 and as a result Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
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- 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
- B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
- B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
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- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0027—Powdering
- B01J37/0036—Grinding
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2510/00—Surface coverings
- F01N2510/06—Surface coverings for exhaust purification, e.g. catalytic reaction
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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Description
本発明は、内燃機関から排出される排気ガスを浄化する処理に適用して好適な排気ガス浄化用触媒及びその製造方法に関する。 The present invention relates to an exhaust gas purifying catalyst suitable for a process for purifying exhaust gas discharged from an internal combustion engine, and a method for manufacturing the same.
現在まで、排気ガス中に含まれる一酸化炭素（ＣＯ）、炭化水素（ＨＣ）及び窒素酸化物（ＮＯｘ）を同時に浄化できる三元触媒の触媒活性成分として、Ｐｔ（白金）、Ｒｈ（ロジウム）、Ｐｄ（パラジウム）等の貴金属が広く知られている。また、これらの貴金属を、例えば、アルミナ、ジルコニア、チタニアなど酸化物担体へ担持させた排気ガス浄化用触媒が広く知られている。これらの排気ガス浄化用触媒は、コージェライト製等のハニカム基材の内壁の表面に塗布形成されて、内燃機関からハニカム基材に導かれた排気ガスを浄化する。 Up to now, Pt (platinum) and Rh (rhodium) have been used as catalytically active components of a three-way catalyst capable of simultaneously purifying carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) contained in exhaust gas. And noble metals such as Pd (palladium) are widely known. Further, exhaust gas purifying catalysts in which these noble metals are supported on an oxide carrier such as alumina, zirconia, and titania are widely known. These exhaust gas purification catalysts are applied and formed on the surface of the inner wall of a honeycomb substrate made of cordierite or the like, and purify the exhaust gas introduced from the internal combustion engine to the honeycomb substrate.
また、排気ガス浄化用触媒には、触媒性能を向上させるために助触媒成分が添加されたものがある。この助触媒成分は、例えば遷移金属の酸化物であって、触媒活性成分である貴金属の粒子に接触又は近接するように添加されることにより、活性サイトとしての機能を発揮して、触媒活性を向上させることができる。 Some exhaust gas purifying catalysts have a promoter component added to improve the catalyst performance. The promoter component is, for example, an oxide of a transition metal, and is added so as to come into contact with or close to particles of the noble metal that is a catalytically active component, thereby exhibiting a function as an active site, thereby improving catalytic activity. Can be improved.
近年、ガソリンエンジンの高出力化又は高速走行の増加などを背景に、自動車の排気ガス温度が高温になる傾向がある。また、エンジンスタート時において、排気ガス浄化触媒が排気ガスを浄化可能な温度になるまでハニカム基材を速やかに昇温させるために、排気ガス浄化触媒が形成されたハニカム基材がエンジン直下に配置されるようになっている。これらのことから、排気ガス浄化触媒は、従来より高い温度域で使用されるようになっている。 In recent years, the exhaust gas temperature of automobiles tends to become high against the background of higher output of gasoline engines or increased high-speed driving. In addition, when the engine is started, the honeycomb base material on which the exhaust gas purification catalyst is formed is placed directly under the engine so that the temperature of the honeycomb base material can be raised quickly until the exhaust gas purification catalyst reaches a temperature at which the exhaust gas can be purified. It has come to be. For these reasons, the exhaust gas purification catalyst is used in a higher temperature range than before.
従来の触媒においては、実際の排気ガス中における耐久性に乏しく、高熱によって貴金属自体に粒成長が生じて活性が低下することがあった。 Conventional catalysts have poor durability in actual exhaust gas, and high heat may cause grain growth in the noble metal itself, resulting in a decrease in activity.
助触媒成分が添加された排気ガス浄化用触媒は、助触媒成分が貴金属粒子近傍に配置されることにより、貴金属粒子周囲の雰囲気変動を遷移金属又は遷移金属化合物によって抑制することができる。このことにより、実際の排気ガス中における貴金属粒子の耐久性を向上させる試みがなされている（特許文献１〜４参照）。なお、このような方策によれば、貴金属粒子の耐久性向上に加えて、貴金属粒子の活性向上も期待することができる。
しかしながら、助触媒成分が貴金属粒子近傍に配置された排気ガス浄化用触媒であって、一般的な含浸法を用いて製造されたものの場合には、製造過程において貴金属粒子及び助触媒成分が液中で凝集し易く、その結果、助触媒成分の粒子が熱凝縮し易い状態となり、触媒の耐久性向上や活性向上を期待することは難しい。 However, in the case of an exhaust gas purifying catalyst in which the promoter component is arranged in the vicinity of the noble metal particles and manufactured using a general impregnation method, the noble metal particles and the promoter component are in the liquid during the manufacturing process. As a result, the cocatalyst component particles are likely to be thermally condensed, and it is difficult to expect improvement in durability and activity of the catalyst.
また、貴金属粒子を、金属酸化物担体として広く利用されているアルミナに担持させた排気ガス浄化用触媒の場合は、高温雰囲気下において貴金属粒子が移動し、貴金属粒子同士が接触することによって貴金属粒子が凝集してしまう。また、遷移金属の化合物はアルミナと固溶しやすいために、遷移金属の化合物を貴金属粒子近傍に単に配置しただけでは貴金属粒子の活性向上効果は得られにくい。 Further, in the case of an exhaust gas purifying catalyst in which noble metal particles are supported on alumina widely used as a metal oxide carrier, the noble metal particles move in a high temperature atmosphere, and the noble metal particles come into contact with each other, thereby precious metal particles. Will aggregate. Further, since the transition metal compound is easily dissolved in alumina, it is difficult to obtain the effect of improving the activity of the noble metal particles simply by arranging the transition metal compound in the vicinity of the noble metal particles.
更に、貴金属粒子を担持したアルミナをセリア（ＣｅＯ２）で被覆した排気ガス浄化用触媒の場合は、貴金属粒子の移動は抑制されるものの、このセリアは耐熱性に乏しいので、高温下において触媒活性は低下してしまうため、触媒の耐久性向上や活性向上は難しかった。 Further, in the case of an exhaust gas purifying catalyst in which alumina supporting noble metal particles is coated with ceria (CeO 2 ), the movement of the noble metal particles is suppressed, but since this ceria has poor heat resistance, catalytic activity at high temperatures is low. Therefore, it was difficult to improve the durability and activity of the catalyst.
本発明に係る排気ガス浄化用触媒は、貴金属粒子と、前記貴金属粒子と接触し、当該貴金属粒子の移動を抑制する第１の化合物と、前記貴金属粒子と前記第１の化合物を内包し、貴金属粒子の移動を抑制すると共に第１の化合物同士の接触に伴う第１の化合物の凝集を抑制する第２の化合物とからなり、前記第１の化合物は、前記貴金属粒子を担持し、かつ、この貴金属粒子を担持した第１の化合物の単体又は集合体を、前記第２の化合物により隔てられた区画内に含み、かつ、前記第１の化合物が、希土類元素を含む複合物であることを要旨とする。 The exhaust gas purifying catalyst according to the present invention includes noble metal particles, a first compound that comes into contact with the noble metal particles and suppresses movement of the noble metal particles, the noble metal particles and the first compound, A second compound that suppresses the movement of the particles and suppresses the aggregation of the first compound accompanying the contact between the first compounds, the first compound carrying the noble metal particles, and Summary of the invention is that a single compound or an aggregate of a first compound supporting noble metal particles is contained in a compartment separated by the second compound, and the first compound is a composite containing a rare earth element. And
また、本発明に係る排気ガス浄化用触媒の製造方法は、本発明に係る排気ガス浄化用触媒を製造する方法であって、第１の化合物を予め焼結させたのち、貴金属粒子をこの第１の化合物上に担持させる工程と、前記貴金属粒子が担持された第１の化合物を粉砕する工程と、前記粉砕された貴金属担持第１の化合物の周囲に、第２の化合物を形成する工程と
を含むことを要旨とする。
The method for producing an exhaust gas purifying catalyst according to the present invention is a method for producing the exhaust gas purifying catalyst according to the present invention, wherein after pre-sintering the first compound, the precious metal particles are added to the precious metal particles. A step of supporting on the first compound, a step of pulverizing the first compound on which the noble metal particles are supported, and a step of forming a second compound around the pulverized noble metal-supporting first compound; It is made to include.
本発明に係る排気ガス浄化用触媒によれば、貴金属粒子が担持される第１の化合物が希土類元素を含む複合物であり、この貴金属粒子と第１の化合物とを第２の化合物で覆うことにより、貴金属粒子の移動と同時に第１の化合物同士の凝集も抑制するので、製造コストや環境負荷を大きくすることなく、第１の化合物による貴金属粒子の活性向上効果を維持することが可能となる。 According to the exhaust gas purifying catalyst of the present invention, the first compound on which the noble metal particles are supported is a composite containing a rare earth element, and the noble metal particles and the first compound are covered with the second compound. Thus, since the aggregation of the first compounds is suppressed simultaneously with the movement of the noble metal particles, it is possible to maintain the effect of improving the activity of the noble metal particles by the first compound without increasing the manufacturing cost and the environmental load. .
本発明に係る排気ガス浄化用触媒の製造方法によれば、本発明に係る排気ガス浄化用触媒を、触媒活性を損なうことなく製造することが可能となる。 According to the method for producing an exhaust gas purification catalyst according to the present invention, the exhaust gas purification catalyst according to the present invention can be produced without impairing the catalytic activity.
以下、本発明の排気ガス浄化用触媒の実施形態について、図面を用いつつ説明する。 Hereinafter, embodiments of an exhaust gas purifying catalyst of the present invention will be described with reference to the drawings.
図１は、本発明の一実施形態となる排気ガス浄化用触媒の模式図である。同図に示す本実施形態の排気ガス浄化用触媒は、触媒活性を有する貴金属粒子１と、この貴金属粒子１と接触し、当該貴金属粒子１の移動を抑制する第１の化合物２と、この貴金属粒子１と第１の化合物２とを内包し、当該貴金属粒子１の移動を抑制すると共に第１の化合物２同士の接触に伴う第１の化合物２の凝集を抑制する第２の化合物３とからなる。この第１の化合物２は、貴金属粒子１を担持している。また、第２の化合物は、貴金属粒子１を担持した第１の化合物２の周囲に形成され、これにより、貴金属粒子１を担持した第１の化合物２の担体又は複数個の集合体が、第２の化合物３により隔てられた区画内に含まれている。 FIG. 1 is a schematic diagram of an exhaust gas purifying catalyst according to an embodiment of the present invention. The exhaust gas purifying catalyst of the present embodiment shown in the figure includes a noble metal particle 1 having catalytic activity, a first compound 2 that contacts the noble metal particle 1 and suppresses the movement of the noble metal particle 1, and the noble metal. From the second compound 3 containing the particle 1 and the first compound 2 and suppressing the movement of the noble metal particle 1 and suppressing the aggregation of the first compound 2 due to the contact between the first compounds 2. Become. The first compound 2 carries noble metal particles 1. The second compound is formed around the first compound 2 carrying the noble metal particles 1, whereby the carrier of the first compound 2 carrying the noble metal particles 1 or a plurality of aggregates are formed. In compartments separated by two compounds 3.
図１に示す本実施形態の排気ガス浄化用触媒は、上述のように第１の化合物２が、貴金属粒子１に接して貴金属粒子１を担持している。このように第１の化合物２が貴金属粒子１を担持していることにより、この第１の化合物２は貴金属粒子１と化学的に結合する。そのため、この第１の化合物２は、貴金属粒子１のアンカー材として作用し、貴金属粒子１の移動を抑制する。このように貴金属粒子１の移動を化学的に抑制することは、貴金属粒子１の凝集を抑制するのに寄与する。 In the exhaust gas purifying catalyst of this embodiment shown in FIG. 1, the first compound 2 is in contact with the noble metal particles 1 and carries the noble metal particles 1 as described above. Since the first compound 2 carries the noble metal particles 1 as described above, the first compound 2 is chemically bonded to the noble metal particles 1. Therefore, the first compound 2 acts as an anchor material for the noble metal particles 1 and suppresses the movement of the noble metal particles 1. Thus, chemically suppressing the movement of the noble metal particles 1 contributes to suppressing aggregation of the noble metal particles 1.
また、本実施形態の排気ガス浄化用触媒は、貴金属粒子１を担持した第１の化合物２を、第２の化合物３で覆い、内包する形態としている。このことにより、第２の化合物３が貴金属粒子１の移動を物理的に抑制する。このように貴金属粒子１の移動の物理的に抑制することは、貴金属粒子１の凝集を抑制するのに寄与する。 In addition, the exhaust gas purifying catalyst of the present embodiment is configured such that the first compound 2 carrying the noble metal particles 1 is covered with the second compound 3 and included. Thereby, the second compound 3 physically suppresses the movement of the noble metal particles 1. Thus, physically suppressing the movement of the noble metal particles 1 contributes to suppressing aggregation of the noble metal particles 1.
更に、この第２の化合物３により隔てられた区画内に、内包された貴金属粒子１と第１の化合物２とを含むことにより、この第２の化合物３により隔てられた区画を越えて第１の化合物２同士が接触し凝集することを抑制する。このように第１の化合物２同士が凝集することを抑制することは、第１の化合物２に担持された貴金属粒子の凝集を抑制するのに寄与する。 Further, by including the precious metal particles 1 and the first compound 2 encapsulated in the section separated by the second compound 3, the first compound beyond the section separated by the second compound 3 is contained. It prevents that compound 2 of these contacts and aggregate. The suppression of aggregation of the first compounds 2 in this way contributes to suppression of aggregation of the noble metal particles supported on the first compound 2.
これらのことにより、本発明の排気ガス浄化用触媒は、製造コストや環境負荷を大きくすることなく、貴金属粒子１の凝集が抑制され、よって貴金属粒子１の凝集による触媒活性低下を防止することができる。また、助触媒としての第１の化合物２は、第２の化合物３により凝集が抑制され、しかも、貴金属粒子１と第２の化合物とに、適切な位置関係になることから、第１の化合物２による貴金属粒子１の活性向上効果を維持することができる。 As a result, the exhaust gas purifying catalyst of the present invention suppresses the aggregation of the noble metal particles 1 without increasing the manufacturing cost and the environmental burden, and thus prevents the catalyst activity from being lowered due to the aggregation of the noble metal particles 1. it can. Further, the first compound 2 as the cocatalyst is prevented from aggregating by the second compound 3 and has an appropriate positional relationship between the noble metal particle 1 and the second compound. The activity improving effect of the noble metal particle 1 due to 2 can be maintained.
本発明の排気ガス浄化用触媒において、第１の化合物２は、希土類元素を含む複合物とすることができる。アンカー材として、貴金属粒子１の移動凝集抑制を可能とする第１の化合物２に、希土類元素を含む複合物を用いることで、この第１の化合物２は貴金属粒子１との高い親和性を発現することが可能となり、その結果、貴金属粒子１が、第１の化合物２上から第２の化合物３に向けて移動することを効果的に抑制することができる。そのため、貴金属粒子１は第１の化合物２上で安定化し、高温排気ガス条件下でも第２の化合物３へと移動せず、貴金属粒子の凝集がいっそう抑制され、数ｎｍ程度の貴金属粒子径を維持可能となる。この貴金属の安定ナノ粒子維持効果により、触媒の耐久性を向上させることができ、排気耐久後も良好な触媒性能を維持可能となる。排気耐久後も良好な触媒性能を維持可能であることは、自動車の排気ガス浄化用触媒として必要な触媒活性を、従来よりも少ない貴金属量で実現可能であることになり、排気ガス浄化用触媒に用いられる貴金属量を従来から大幅に低減可能となる。 In the exhaust gas purifying catalyst of the present invention, the first compound 2 can be a composite containing a rare earth element. By using a composite containing a rare earth element as the first compound 2 capable of suppressing migration aggregation of the noble metal particles 1 as the anchor material, the first compound 2 exhibits high affinity with the noble metal particles 1. As a result, the movement of the noble metal particle 1 from the first compound 2 toward the second compound 3 can be effectively suppressed. Therefore, the noble metal particle 1 is stabilized on the first compound 2 and does not move to the second compound 3 even under high-temperature exhaust gas conditions, and the aggregation of the noble metal particles is further suppressed, and the noble metal particle diameter is about several nm. Can be maintained. The durability of the catalyst can be improved by the effect of maintaining the stable nanoparticles of the noble metal, and good catalyst performance can be maintained after exhaust durability. The ability to maintain good catalytic performance even after exhaust durability means that the catalytic activity required for automobile exhaust gas purification catalysts can be achieved with less noble metal than in the past. The amount of noble metal used in the conventional process can be greatly reduced.
第１の化合物２に、希土類元素を含む複合物を用いることにより、貴金属粒子１の、第１の化合物２上から第２の化合物３への移動凝集が抑制される理由の詳細は、必ずしも明らかではないが、希土類元素のような表面酸素が大量にあるような化合物を第１の化合物２に適用することにより、この表面酸素を介し、第１の化合物２が貴金属粒子１と強固な共有結合を形成しているためと考えられる。 Details of the reason why the migration aggregation of the noble metal particles 1 from the first compound 2 to the second compound 3 is suppressed by using a composite containing a rare earth element for the first compound 2 are not necessarily clear. However, by applying a compound having a large amount of surface oxygen, such as a rare earth element, to the first compound 2, the first compound 2 is strongly bonded to the noble metal particle 1 through the surface oxygen. This is thought to be due to the formation of
本発明の排気ガス浄化用触媒において、第１の化合物２は、希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む複合物とすることが好適である。アンカー材として、貴金属粒子１の移動凝集抑制を可能とする第１の化合物２に、希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む複合物を用いることで、この第１の化合物２は貴金属粒子１との高い親和性を発現することが可能となり、その結果、貴金属粒子１が、第１の化合物２上から第２の化合物３に向けて移動することを効果的に抑制することができる。そのため、貴金属粒子１は第１の化合物２上で安定化し、高温排気ガス条件下でも第２の化合物３へと移動せず、貴金属粒子１の凝集がいっそう抑制され、数ｎｍ程度の貴金属粒子径を維持可能となる。この貴金属の安定ナノ粒子維持効果により、触媒の耐久性を向上させることができ、排気耐久後も良好な触媒性能を維持可能となる。排気耐久後も良好な触媒性能を維持可能であることは、自動車の排気ガス浄化用触媒として必要な触媒活性を、従来よりも少ない貴金属量で実現可能であることになり、排気ガス浄化用触媒に用いられる貴金属量を従来から大幅に低減可能となる。 In the exhaust gas purifying catalyst of the present invention, the first compound 2 is preferably a composite containing a rare earth element and at least one kind of alkali metal and alkaline earth metal. By using, as the anchor material, a composite containing a rare earth element and at least one kind of alkali metal and alkaline earth metal as the first compound 2 that enables the movement aggregation of the noble metal particles 1 to be suppressed. The first compound 2 can exhibit high affinity with the noble metal particle 1, and as a result, the noble metal particle 1 moves from the first compound 2 toward the second compound 3. Can be effectively suppressed. Therefore, the noble metal particles 1 are stabilized on the first compound 2 and do not move to the second compound 3 even under high-temperature exhaust gas conditions, and the aggregation of the noble metal particles 1 is further suppressed, and the noble metal particle diameter of about several nm. Can be maintained. The durability of the catalyst can be improved by the effect of maintaining the stable nanoparticles of the noble metal, and good catalyst performance can be maintained after exhaust durability. The ability to maintain good catalytic performance even after exhaust durability means that the catalytic activity required for automobile exhaust gas purification catalysts can be achieved with less noble metal than in the past. The amount of noble metal used in the conventional process can be greatly reduced.
第１の化合物２に、希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む複合物を用いることにより、貴金属粒子１の、第１の化合物２上から第２の化合物３への移動凝集が抑制される理由の詳細は、必ずしも明らかではないが、希土類元素のような表面酸素が大量にあるような化合物を第１の化合物２に適用することにより、この表面酸素を介し、第１の化合物２が貴金属粒子１と強固な共有結合を形成しているためと考えられる。更に、電子放出し易いアルカリ性の、アルカリ金属及びアルカリ土類金属のうち少なくとも１種を第１の化合物２に含むことで、この酸素への電子供与が生じ、前述の共有結合性を更に強めているものと考えられる。 By using a composite containing a rare earth element and at least one kind of alkali metal and alkaline earth metal as the first compound 2, the noble metal particles 1 can be secondly added from above the first compound 2. Although the details of the reason why the migration aggregation to the compound 3 is suppressed are not necessarily clear, by applying a compound having a large amount of surface oxygen such as a rare earth element to the first compound 2, This is probably because the first compound 2 forms a strong covalent bond with the noble metal particle 1 through oxygen. Furthermore, by including at least one of alkaline, alkaline earth metal and alkaline earth metal that is easy to emit electrons in the first compound 2, electron donation to the oxygen occurs, and the above-described covalent bond is further strengthened. It is thought that there is.
本発明の排気ガス浄化用触媒において、第１の化合物２は、希土類元素と、ジルコニウムとを含む複合物とすることも好適である。アンカー材として、貴金属粒子１の移動凝集抑制を可能とする第１の化合物２に、希土類元素と、ジルコニウムとを含む複合物を用いることで、この第１の化合物２は貴金属粒子１との高い親和性を発現することが可能となり、その結果、貴金属粒子１が、第１の化合物２上から第２の化合物３に向けて移動することを効果的に抑制することができる。そのため、貴金属粒子１は第１の化合物２上で安定化し、高温排気ガス条件下でも第２の化合物３へと移動せず、貴金属粒子の凝集がいっそう抑制され、数ｎｍ程度の貴金属粒子径を維持可能となる。この貴金属の安定ナノ粒子維持効果により、触媒の耐久性を向上させることができ、排気耐久後も良好な触媒性能を維持可能となる。排気耐久後も良好な触媒性能を維持可能であることは、自動車の排気ガス浄化用触媒として必要な触媒活性を、従来よりも少ない貴金属量で実現可能であることになり、排気ガス浄化用触媒に用いられる貴金属量を従来から大幅に低減可能となる。 In the exhaust gas purifying catalyst of the present invention, the first compound 2 is also preferably a composite containing a rare earth element and zirconium. By using a composite containing a rare earth element and zirconium as the first compound 2 that enables the migration aggregation of the noble metal particles 1 to be suppressed as an anchor material, the first compound 2 is high in comparison with the noble metal particles 1. Affinity can be expressed, and as a result, the movement of the noble metal particle 1 from the first compound 2 toward the second compound 3 can be effectively suppressed. Therefore, the noble metal particle 1 is stabilized on the first compound 2 and does not move to the second compound 3 even under high-temperature exhaust gas conditions, and the aggregation of the noble metal particles is further suppressed, and the noble metal particle diameter is about several nm. Can be maintained. The durability of the catalyst can be improved by the effect of maintaining the stable nanoparticles of the noble metal, and good catalyst performance can be maintained after exhaust durability. The ability to maintain good catalytic performance even after exhaust durability means that the catalytic activity required for automobile exhaust gas purification catalysts can be achieved with less noble metal than in the past. The amount of noble metal used in the conventional process can be greatly reduced.
第１の化合物２に、希土類元素と、ジルコニウムとを含む複合物を用いることにより、貴金属粒子１の、第１の化合物２上から第２の化合物３への移動凝集が抑制される理由の詳細は、必ずしも明らかではないが、希土類元素のような表面酸素が大量にあるような化合物を第１の化合物２に適用することにより、この表面酸素を介し、第１の化合物２が貴金属粒子１と強固な共有結合を形成しているためと考えられる。更に、第１の化合物２にＺｒを添加することにより、アンカー材としての第１の化合物２の安定度を更に向上させ、その結果、より貴金属の安定化効果を発揮可能となる。また、第１の化合物内にアルカリ元素又はアルカリ土類元素を含まない場合、このアンカー材内の希土類元素とＺｒ元素との組成は、Ｚｒリッチとすることで、第１の化合物がジルコニアと同様の結晶構造を有することになり、第１の化合物をより安定化させることができるようになる。 Details of the reason why the migration aggregation of the noble metal particles 1 from the first compound 2 to the second compound 3 is suppressed by using a composite containing a rare earth element and zirconium for the first compound 2. Although it is not necessarily clear, by applying a compound having a large amount of surface oxygen, such as a rare earth element, to the first compound 2, the first compound 2 and the noble metal particles 1 are bonded via the surface oxygen. This is probably because a strong covalent bond is formed. Furthermore, by adding Zr to the first compound 2, the stability of the first compound 2 as the anchor material is further improved, and as a result, the effect of stabilizing the noble metal can be exhibited. When the first compound does not contain an alkali element or an alkaline earth element, the composition of the rare earth element and the Zr element in the anchor material is Zr-rich so that the first compound is the same as zirconia. Thus, the first compound can be further stabilized.
図２は、本発明に係る排ガス浄化用触媒の金属組織写真の一例である。図２（ａ）は、第１の化合物が希土類と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む複合物である例であり、具体的には、第１の化合物がＣｅＭｇＯｘ系の化合物である例である。図２（ｂ）は、第１の化合物が希土類とジルコニウムとを含む複合物である例であり、具体的には、第１の化合物がＺｒＣｅＯｘ系の化合物である例である。これらの写真に示されるように、貴金属粒子としてのＰｄ粒子は、アンカー材である第１の化合物に担持され、このＰｄ粒子を担持した第１の化合物を覆うように包接材である第２の化合物が形成されている。 FIG. 2 is an example of a metallographic photograph of the exhaust gas purifying catalyst according to the present invention. FIG. 2A is an example in which the first compound is a composite containing a rare earth and at least one metal of an alkali metal and an alkaline earth metal. Specifically, the first compound Is an example of a CeMgOx-based compound. FIG. 2B is an example in which the first compound is a composite containing a rare earth and zirconium, and specifically, an example in which the first compound is a ZrCeOx-based compound. As shown in these photographs, the Pd particles as the noble metal particles are supported by the first compound that is the anchor material, and the second material that is the inclusion material so as to cover the first compound that supports the Pd particles. Is formed.
本発明に係る排気ガス浄化用触媒において、第１の化合物２である複合物における当該希土類元素は、Ｌａ、Ｃｅ、Ｐｒ及びＮｄから選ばれる少なくとも１種を含むことが好ましい。Ｌａ、Ｃｅ、Ｐｒ及びＮｄは、いずれも、熱安定性も高く、上述した表面酸素の供与性が高いため、先に述べた本発明における第１の化合物２の作用効果を、より得易くなる。 In the exhaust gas purifying catalyst according to the present invention, the rare earth element in the composite that is the first compound 2 preferably contains at least one selected from La, Ce, Pr, and Nd. La, Ce, Pr, and Nd all have high thermal stability and high surface oxygen donating property, so that the effects of the first compound 2 in the present invention described above can be obtained more easily. .
第１の化合物２である複合物における当該希土類元素は、さらに、Ｙを含むことができる。Ｙを添加することにより、貴金属の微粒子維持効果を維持しつつ、排気耐久後のアンカー材のOSC機能を、より維持できるようになる。この結果、車両走行中の加減速時に、A/F比（Air Fuel Ratio）が大きく変化した際の雰囲気を緩和できる。その結果、本触媒構造により維持可能となったナノ貴金属粒子への酸素吸放出が可能となり、結果、更なる排ガスエミッションの低減、あるいは、貴金属使用量の低減が可能となる。 The rare earth element in the composite that is the first compound 2 can further contain Y. By adding Y, it is possible to further maintain the OSC function of the anchor material after exhaust durability while maintaining the precious metal fine particle maintaining effect. As a result, it is possible to relax the atmosphere when the A / F ratio (Air Fuel Ratio) changes greatly during acceleration / deceleration during vehicle travel. As a result, it is possible to absorb and release oxygen into the nano noble metal particles that can be maintained by the present catalyst structure, and as a result, it is possible to further reduce exhaust gas emissions or reduce the amount of noble metal used.
Ｙを添加することによる上記効果は、特に第１の化合物２がＺｒを含む複合物である場合に特に有利に発揮される。本発明の実施形態に係る触媒は、それ自身高い耐熱性を有しているものの、Ｙを組み合わせることで、ジルコニア系アンカー材の結晶構造を安定化させ、これにより耐熱性をさらに高めることが可能となる。これは、排気耐久中にジルコニア結晶構造が正方晶から単斜晶に変質する相転移を抑制し、結果、そもそものOSC能が低下してしまうことを抑制できるためである。 The above-mentioned effect due to the addition of Y is particularly advantageous when the first compound 2 is a composite containing Zr. The catalyst according to the embodiment of the present invention itself has high heat resistance, but by combining Y, the crystal structure of the zirconia-based anchor material can be stabilized, thereby further improving the heat resistance. It becomes. This is because it is possible to suppress a phase transition in which the zirconia crystal structure is changed from a tetragonal crystal to a monoclinic crystal during exhaust durability, and as a result, it is possible to suppress a decrease in OSC ability.
また、上記第１の化合物２が、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種を含む場合において、このアルカリ金属又はアルカリ土類金属は、Ｎａ、Ｋ、Ｒｂ、Ｃｓ、Ｍｇ、Ｃａ、Ｓｒ及びＢａから選ばれる少なくとも1種を含むことが好ましい。特に、アルカリ土類金属であることがより好ましい。これらのＮａ、Ｋ、Ｒｂ、Ｃｓ、Ｍｇ、Ｃａ、Ｓｒ及びＢａは、いずれも、昇華などが起きず、熱安定性が高いため、先に述べた電子供与性が安定しているのものと考えられる。特に、アルカリ土類金属は、この電子供与性はアルカリ金属よりも若干低いものの、希土類元素との複合性を生じ易いため、貴金属粒子との親和性の高い複合物としての第１の化合物を形成することができる。 In the case where the first compound 2 contains at least one of alkali metal and alkaline earth metal, the alkali metal or alkaline earth metal is Na, K, Rb, Cs, Mg, Ca, It is preferable to include at least one selected from Sr and Ba. In particular, an alkaline earth metal is more preferable. These Na, K, Rb, Cs, Mg, Ca, Sr and Ba all have no sublimation or the like, and have high thermal stability, so that the electron donating property described above is stable. Conceivable. In particular, alkaline earth metals have a slightly lower electron donating property than alkali metals, but easily form composites with rare earth elements, so that the first compound is formed as a composite having high affinity with noble metal particles. can do.
第１の化合物２は、上述した希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む場合に、更にＺｒを含有させることができる。第１の化合物２が希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とに加えて、Ｚｒを含むことで、更に高い酸素吸蔵能（ＯＳＣ）を付与でき、より効果を発揮できる。また、第１の化合物２に更にＺｒを含有させて複合化させることで、貴金属粒子のナノ粒子安定化効果を、より引き出すことが可能となる。この詳細は不明だが、ナノ粒子を維持可能となったことで、排気ガスと接触可能な面積が増え、これに伴い酸素供給が必要となるところ、Ｚｒを含有させることにより、ナノ粒子安定化効果（アンカー効果）とナノ貴金属へのスムーズな酸素供給効果の両立が可能となる。 When the first compound 2 includes the rare earth element described above and at least one metal selected from alkali metals and alkaline earth metals, it can further contain Zr. When the first compound 2 contains Zr in addition to the rare earth element and at least one of the alkali metal and the alkaline earth metal, it can impart a higher oxygen storage capacity (OSC), and is more effective. Can be demonstrated. In addition, by incorporating Zr into the first compound 2 and making it complex, it becomes possible to further bring out the nanoparticle stabilization effect of the noble metal particles. Although the details are unknown, the ability to maintain nanoparticles increases the area that can be contacted with exhaust gas, and as a result, oxygen supply is required. (Anchor effect) and smooth oxygen supply effect to nano-noble metals can both be achieved.
この第１の化合物２に担持される貴金属粒子１は、その成分にＰｔ、Ｐｄ及びＲｈから選ばれる少なくとも１種を含むことが好ましい。Ｐｔ、Ｐｄ及びＲｈは、いずれも、排気ガスを浄化し得る触媒活性を有する成分である。また、第１の化合物が上述した作用効果を十分に発揮させることができ、第１の化合物上で安定化する貴金属である。貴金属粒子１が、Ｐｔ、Ｐｄ及びＲｈの少なくとも１種を含むことにより、この貴金属粒子１は第１の化合物２の表面酸素との親和性が高いため、第１の化合物２表面から第２の化合物への移動が生じない。 The noble metal particle 1 supported on the first compound 2 preferably contains at least one selected from Pt, Pd and Rh as its component. Pt, Pd and Rh are all components having catalytic activity capable of purifying exhaust gas. In addition, the first compound is a noble metal that can sufficiently exhibit the above-described effects and is stabilized on the first compound. Since the noble metal particle 1 contains at least one of Pt, Pd and Rh, the noble metal particle 1 has a high affinity with the surface oxygen of the first compound 2, so There is no transfer to the compound.
貴金属粒子１は、上掲したＰｔ、Ｐｄ及びＲｈのなかでも、Ｐｄであることが、より好ましい。本発明の排気ガス浄化用触媒における第１の化合物２に対する貴金属粒子１の組み合わせとしては、特にＰｄであることが有効である。これは、先に述べた第１の化合物２の効果に関して、特にＰｄが、第１の化合物２との親和性が高いため、貴金属粒子１の埋没抑制効果を加味し、最も効果が発揮されるためである。 The precious metal particles 1 are more preferably Pd among the above-mentioned Pt, Pd and Rh. As the combination of the noble metal particles 1 with the first compound 2 in the exhaust gas purification catalyst of the present invention, it is particularly effective to use Pd. This is because the effect of the first compound 2 described above is particularly effective because Pd has a high affinity with the first compound 2 and the effect of suppressing the burying of the noble metal particles 1 is taken into account. Because.
第２の化合物３は、本発明の排気ガス浄化用触媒では特に限定されないが、Ａｌ及びＺｒの中から選ばれる少なくとも一つの元素の酸化物であることが望ましい。なかでも、第２の化合物３がアルミナであることは、第２の化合物３を多孔質とすることができるので好ましい。第２の化合物３が多孔質であることにより、本発明の排気ガス浄化用触媒の構造では、排気ガスが第２の化合物３を通過して第１の化合物２に担持された貴金属粒子１に十分に到達することが可能となる。 The second compound 3 is not particularly limited in the exhaust gas purifying catalyst of the present invention, but is desirably an oxide of at least one element selected from Al and Zr. Among these, it is preferable that the second compound 3 is alumina because the second compound 3 can be made porous. Since the second compound 3 is porous, in the structure of the exhaust gas purifying catalyst of the present invention, the exhaust gas passes through the second compound 3 to the noble metal particles 1 supported on the first compound 2. It is possible to reach it sufficiently.
第２の化合物３が、アルミナに加えて、更に、Ｃｅ、Ｚｒ、Ｌａ及びＢａから選ばれる少なくとも1種の元素を含むことは、より好ましい。本発明に係る排気ガス浄化用触媒における貴金属粒子１を担持した第１の化合物２の粒を、安定に維持するために、Ｃｅ、Ｚｒ、Ｌａ及びＢａから選ばれる少なくとも1種の元素を第２の化合物（包摂材）に添加することで、包摂材としてのアルミナの耐熱性を向上させることが可能となる。これにより、例えば、Ｃｅ、Ｚｒ、Ｌａ及びＢａから選ばれる少なくとも1種の元素を添加しない場合に比較し、アルミナの劣化状態であるαアルミナ化を抑制可能とすることができ、結果、本発明に係る構造を有する触媒の耐久性を更に高めることが可能となる。更に、貴金属粒子１がＰｄの場合、低温始動時のＨＣなどによる被毒を受けやすいという本質的な課題があるが、第２の化合物にＢａを添加させることで、このＨＣ被毒作用を緩和し、その結果、低温活性化を図ることも可能となる。 It is more preferable that the second compound 3 further contains at least one element selected from Ce, Zr, La and Ba in addition to alumina. In order to stably maintain the particles of the first compound 2 supporting the noble metal particles 1 in the exhaust gas purifying catalyst according to the present invention, at least one element selected from Ce, Zr, La and Ba is used as the second compound. By adding to this compound (inclusion material), it becomes possible to improve the heat resistance of alumina as the inclusion material. Thereby, compared with the case where at least one element selected from, for example, Ce, Zr, La and Ba is not added, it is possible to suppress α-alumination, which is a deteriorated state of alumina, and as a result, the present invention. The durability of the catalyst having the structure according to the above can be further enhanced. Furthermore, when the noble metal particle 1 is Pd, there is an essential problem that it is susceptible to poisoning due to HC at the time of low temperature starting, but this HC poisoning action is mitigated by adding Ba to the second compound. As a result, low-temperature activation can be achieved.
本発明に係る排気ガス用触媒において、当該排気ガス用触媒粉末の第１の化合物２の結晶子径（Ｄ１）と、貴金属粒子が担持された第１の化合物の二次粒子径（Ｄ２）とについて、Ｄ１に対するＤ２の比Ｄ２／Ｄ１が、１≦Ｄ２／Ｄ１≦５０であることが好ましい。上述した複合物よりなる第１の化合物２は、貴金属との親和性が高いため、ナノ貴金属粒子１の状態を維持できるものの、この第１の化合物２が高温で凝集し、また、焼結して二次粒子となる際には、この第１の化合物２上に担持されたナノ貴金属粒子１が、第１の化合物２の二次粒子内に取り込まれてしまうことがある。その結果、排気ガスと接触可能な貴金属粒子数が減るため、本発明による貴金属粒子のナノ粒子維持による効果が相対的に薄らいでしまうおそれがある。 In the exhaust gas catalyst according to the present invention, the crystallite diameter (D1) of the first compound 2 of the exhaust gas catalyst powder and the secondary particle diameter (D2) of the first compound on which noble metal particles are supported The ratio D2 / D1 of D2 to D1 is preferably 1 ≦ D2 / D1 ≦ 50. Since the first compound 2 made of the composite described above has a high affinity with the noble metal, the state of the nano noble metal particles 1 can be maintained, but the first compound 2 aggregates at a high temperature and is sintered. When the particles become secondary particles, the nano noble metal particles 1 supported on the first compound 2 may be taken into the secondary particles of the first compound 2 in some cases. As a result, since the number of noble metal particles that can come into contact with the exhaust gas is reduced, the effect of maintaining the nanoparticles of the noble metal particles according to the present invention may be relatively diminished.
そこで、この第１の化合物２内部への貴金属粒子１の埋没を抑制し、貴金属粒子１のナノ粒子維持効果を十分に発揮させるためには、貴金属粒子が担持された第１の化合物２の二次粒子径Ｄ２が、第１の化合物２の結晶子径Ｄ１に対して過度に大きくないようにする。つまり、焼結した後であっても第１の化合物２の二次粒子径Ｄ２が、過度に大きくないようにする。具体的には、Ｄ１に対するＤ２の比Ｄ２／Ｄ１が、１≦Ｄ２／Ｄ１≦５０の範囲にあるようにする。この範囲とすることで、貴金属粒子１が第１の化合物２の二次粒子の表面に十分に露出することが可能となる。 Therefore, in order to suppress the burying of the noble metal particles 1 inside the first compound 2 and to sufficiently exhibit the nanoparticle maintaining effect of the noble metal particles 1, the second compound 2 of the first compound 2 supporting the noble metal particles 1 is used. The secondary particle diameter D2 is not excessively large with respect to the crystallite diameter D1 of the first compound 2. That is, even after sintering, the secondary particle diameter D2 of the first compound 2 is set not to be excessively large. Specifically, the ratio D2 / D1 of D2 to D1 is set in a range of 1 ≦ D2 / D1 ≦ 50. By setting it as this range, the noble metal particles 1 can be sufficiently exposed on the surface of the secondary particles of the first compound 2.
詳述すると、本発明の排気ガス浄化用触媒において、第１の化合物２は、第２の化合物３により内包されて固定化されているので、この第２の化合物３を飛び出すように移動することがない。そのため、この第１の化合物２は、凝集、焼結するとき、この第２の化合物３に内包された区画内で二次粒子としてのみ焼結する。そこで、第１の化合物２に担持された貴金属粒子１が第１の化合物２の二次粒子内に埋没しないようにするには、第２の化合物３に内包された区画内における第１の化合物２の二次粒子が、一個の結晶体である一次粒子の状態であること、すなわち、Ｄ２／Ｄ１＝１が理想状態であり、最も好ましい（Ｄ２／Ｄ１＜１は有り得ない）。また、Ｄ２／Ｄ１の値が５０を超えると、貴金属粒子１はナノ粒子状態を維持可能であるものの、この貴金属粒子１の第１の化合物２の二次粒子内への埋没が多く生じ、本発明で所期した貴金属粒子のナノ粒子状態維持による効果を発揮し難くなる。そこで、Ｄ１に対するＤ２の比Ｄ２／Ｄ１は、１≦Ｄ２／Ｄ１≦５０の範囲にあることが好ましい。なお、Ｄ１は、排気ガス浄化用触媒粉末のＸＲＤ回折（ＸＲＤ）により調べることができ、Ｄ２は光分光法により平均粒度を調べることができる。 More specifically, in the exhaust gas purifying catalyst of the present invention, the first compound 2 is contained and fixed by the second compound 3, so that the second compound 3 moves so as to jump out. There is no. For this reason, when the first compound 2 is aggregated and sintered, it is sintered only as secondary particles in a compartment included in the second compound 3. Therefore, in order to prevent the noble metal particles 1 supported on the first compound 2 from being buried in the secondary particles of the first compound 2, the first compound in the compartment included in the second compound 3 is used. The secondary particles 2 are in the state of primary particles that are one crystal body, that is, D2 / D1 = 1 is the ideal state, and most preferable (D2 / D1 <1 is not possible). When the value of D2 / D1 exceeds 50, the noble metal particle 1 can maintain the nanoparticle state, but the noble metal particle 1 is often embedded in the secondary particles of the first compound 2, It becomes difficult to exhibit the effect of maintaining the nanoparticle state of the noble metal particles as expected in the invention. Therefore, the ratio D2 / D1 of D2 to D1 is preferably in the range of 1 ≦ D2 / D1 ≦ 50. D1 can be examined by XRD diffraction (XRD) of the exhaust gas purifying catalyst powder, and D2 can be examined by an optical spectroscopy for the average particle size.
図３は、Ｄ１に対するＤ２の比Ｄ２／Ｄ１と、排気浄化用触媒のＨＣの転化率が５０％になる温度との関係を示すグラフである。図３から分かるようにＤ１に対するＤ２の比Ｄ２／Ｄ１が１≦Ｄ２／Ｄ１≦５０の範囲にあるときに、良好な排気ガス浄化特性が得られている。 FIG. 3 is a graph showing the relationship between the ratio D2 / D1 of D2 to D1 and the temperature at which the HC conversion rate of the exhaust purification catalyst becomes 50%. As can be seen from FIG. 3, when the ratio D2 / D1 of D2 to D1 is in the range of 1 ≦ D2 / D1 ≦ 50, good exhaust gas purification characteristics are obtained.
図４は、Ｄ２／Ｄ１が１≦Ｄ２／Ｄ１≦５０の範囲にある排気ガス浄化用触媒の９００℃での排気耐久試験後の顕微鏡組織写真である。図４から分かるように、Ｄ２／Ｄ１が１≦Ｄ２／Ｄ１≦５０にあるときには、ナノ粒子の貴金属粒子が、第１の化合物の表面に担持されており、第１の化合物の内部に埋没してはいなかった。 FIG. 4 is a micrograph of the exhaust gas after the exhaust gas durability test at 900 ° C. of the exhaust gas purifying catalyst in which D2 / D1 is in the range of 1 ≦ D2 / D1 ≦ 50. As can be seen from FIG. 4, when D2 / D1 is 1 ≦ D2 / D1 ≦ 50, the noble metal particles of the nanoparticles are supported on the surface of the first compound and buried in the first compound. It was not.
Ｄ１に対するＤ２の比Ｄ２／Ｄ１の、より好ましい範囲は、１≦Ｄ２／Ｄ１≦２０である。Ｄ２／Ｄ１が、１≦Ｄ２／Ｄ１≦２０であるときに、上記効果をより発揮できる。その理由は、必ずしも明らかではないが、１≦Ｄ２／Ｄ１≦２０の範囲では、第２の化合物３により区画されたユニット内における第１の化合物２の二次粒子内の巻き込まれることによる貴金属粒子１の露出面積低下が生じ難く、貴金属粒子１の微粒子状態維持による性能向上代が、より得られるためと考えられる。図３に示したグラフにおいても、１≦Ｄ２／Ｄ１≦２０の範囲では、排気ガス浄化特性が特に優れている。 A more preferable range of the ratio D2 / D1 of D2 to D1 is 1 ≦ D2 / D1 ≦ 20. When D2 / D1 is 1 ≦ D2 / D1 ≦ 20, the above effect can be more exhibited. The reason is not necessarily clear, but in the range of 1 ≦ D2 / D1 ≦ 20, noble metal particles by being involved in the secondary particles of the first compound 2 in the unit partitioned by the second compound 3 This is probably because the exposed area reduction of No. 1 is less likely to occur, and a performance improvement allowance by maintaining the fine particle state of the noble metal particles 1 can be obtained more. Also in the graph shown in FIG. 3, the exhaust gas purification characteristics are particularly excellent in the range of 1 ≦ D2 / D1 ≦ 20.
本発明に係る排気ガス用触媒において、当該排気ガス用触媒粉末のＮ2吸着分析により求めた粉末細孔容積が、粉末1ｇあたり、0.3[ｍl/g]〜0.5[ｍl/g]、かつ、平均細孔径が30[nm]以下であることが好ましい。本発明に係る排気ガス用触媒粉末が、このような条件を満たす細孔構造を有することで、第１の化合物粒内に微粒子のまま維持されている触媒活性点（貴金属粒子）に対し、有害排気ガスを到達可能なものとし、結果、触媒性能を充分に引き出すことが可能となる。粉末細孔容積が、粉末1ｇあたり、0.3[ｍl/g]に満たない場合には、ガス拡散性が低下し、ナノ活性点の有効活用ができにくくなり、結果、排ガス浄化性能低下が生じやすくなる。また、0.5[ｍl/g]を超えると、ガス拡散性は充分であるが、触媒コート層がもろくなりやすく、コート層の剥離などの問題が生じるようになる。また、平均細孔径が30[nm]を超えると、貴金属担持第一の化合物粒の移動・凝集が生じやすくなり、結果、第一の化合物粒内の貴金属粒の埋没を生じ、触媒性能の低下を生じる。 In the exhaust gas catalyst according to the present invention, the powder pore volume determined by N 2 adsorption analysis of the exhaust gas catalyst powder is 0.3 [ml / g] to 0.5 [ml / g] per 1 g of powder, and The average pore diameter is preferably 30 [nm] or less. Since the exhaust gas catalyst powder according to the present invention has a pore structure that satisfies such conditions, it is harmful to the catalyst active points (noble metal particles) maintained as fine particles in the first compound particles. The exhaust gas can be reached, and as a result, the catalyst performance can be sufficiently extracted. If the pore volume of the powder is less than 0.3 [ml / g] per gram of powder, gas diffusibility will be reduced, making it difficult to effectively use nano-active sites, and as a result, exhaust gas purification performance will be reduced. Become. On the other hand, if it exceeds 0.5 [ml / g], the gas diffusibility is sufficient, but the catalyst coat layer tends to be brittle and causes problems such as peeling off of the coat layer. In addition, when the average pore diameter exceeds 30 [nm], movement and aggregation of the noble metal-supported first compound particles are likely to occur, resulting in embedding of the noble metal particles in the first compound particles, resulting in a decrease in catalyst performance. Produce.
本発明の排気ガス浄化用触媒は、第２の化合物３により隔てられた区画内に、貴金属粒子を合計で８×１０−２０モル以下の量で含有することが好ましい。図１に示したように、貴金属粒子１は、第１の化合物とともに第２の化合物３に内包されている。この第２の化合物３により隔てられた区画内に含まれる複数個の貴金属粒子１は、高温により移動する場合があるが、アンカー材としての第１の化合物２の効果によって第２の化合物３には移動せず、第２の化合物３により隔てられた区画内（ユニット内）でのみ移動し、一つ又は複数個の貴金属粒に凝集する。 The exhaust gas purifying catalyst of the present invention preferably contains noble metal particles in a total amount of 8 × 10 −20 mol or less in the compartments separated by the second compound 3. As shown in FIG. 1, the noble metal particle 1 is included in the second compound 3 together with the first compound. The plurality of noble metal particles 1 contained in the compartment separated by the second compound 3 may move at a high temperature, but the second compound 3 is converted into the second compound 3 by the effect of the first compound 2 as an anchor material. Does not move, moves only within the compartment (within the unit) separated by the second compound 3, and aggregates into one or more noble metal particles.
ここに、一つのユニット内で貴金属粒が凝集した場合に、凝集した貴金属粒の粒径が１０［ｎｍ］以下であれば、充分な触媒活性を示し、凝集による触媒活性の劣化を抑制することができる。図５は、触媒活性を有する貴金属としての白金やパラジウムについて、貴金属粒子径と貴金属表面積との関係を示すグラフである。なお、同図では貴金属が白金の場合とパラジウムの場合と、ほぼ同じ曲線を示すので、一つの曲線として示している。同図から明らかなように、貴金属の粒子径が１０［ｎｍ］以下であれば粒子表面積が大きく、十分な活性が得られるので、凝集による触媒活性の劣化を抑制することができる。 Here, when noble metal particles are aggregated in one unit, if the aggregated noble metal particles have a particle size of 10 nm or less, sufficient catalytic activity is exhibited and deterioration of catalytic activity due to aggregation is suppressed. Can do. FIG. 5 is a graph showing the relationship between the noble metal particle diameter and the noble metal surface area for platinum or palladium as a noble metal having catalytic activity. In the figure, since the curves are almost the same when the noble metal is platinum and palladium, they are shown as one curve. As is clear from the figure, when the particle diameter of the noble metal is 10 [nm] or less, the particle surface area is large and sufficient activity can be obtained, so that deterioration of the catalyst activity due to aggregation can be suppressed.
図６は、触媒活性を有する貴金属としての白金やパラジウムについて、貴金属粒子径と貴金属の原子数との関係を示すグラフである。なお、同図では貴金属が白金の場合とパラジウムの場合と、ほぼ同じ曲線を示すので、一つの曲線として示している。同図から明らかなように、貴金属の粒子径が１０［ｎｍ］であるときの原子数は約４８０００個であり、この値をモル数に換算すると約８×１０−２０モル以下の量になる。 FIG. 6 is a graph showing the relationship between the noble metal particle diameter and the number of noble metal atoms for platinum or palladium as a noble metal having catalytic activity. In the figure, since the curves are almost the same when the noble metal is platinum and palladium, they are shown as one curve. As is clear from the figure, the number of atoms when the particle diameter of the noble metal is 10 [nm] is about 48000, and when this value is converted into the number of moles, the amount is about 8 × 10 −20 moles or less. .
これらの観点から、ユニット内の貴金属量を制限し、８×１０−２０モル以下の量とすることで、ユニット内で1個に凝集しても、触媒活性の劣化を抑制することができる。 From these viewpoints, by limiting the amount of noble metal in the unit and setting it to an amount of 8 × 10 −20 mol or less, deterioration of the catalyst activity can be suppressed even if it aggregates into one in the unit.
ユニット内に含まれる貴金属量を８×１０−２０モル以下に低減する手段としては、第１の化合物２の貴金属粒子１の担持濃度を下げること、又は貴金属粒子１を担持した第１の化合物２の粒径を小さくすることの、２つの手段が存在する。本発明では、これらの手段に限定しないが、実際の触媒製造を考えた場合には、前者の担持濃度を下げる方法では、所定の排気ガス浄化触媒の性能を維持するためには排気ガス浄化用触媒をコートしたハニカム担体の容積を増やさなければならず、したがって、触媒のコート量が通常の一桁多いようなコート量をハニカム担体へコートする必要があるため、現実的ではない。 As a means for reducing the amount of the noble metal contained in the unit to 8 × 10 −20 mol or less, the concentration of the noble metal particles 1 of the first compound 2 is lowered or the first compound 2 carrying the noble metal particles 1 is used. There are two means of reducing the particle size of the. In the present invention, although not limited to these means, when actual catalyst production is considered, the former method of lowering the supported concentration can be used for exhaust gas purification in order to maintain the performance of a predetermined exhaust gas purification catalyst. Since the volume of the honeycomb carrier coated with the catalyst has to be increased, and therefore, it is necessary to coat the honeycomb carrier with a coating amount that is usually an order of magnitude larger than that of the catalyst, it is not practical.
次に、貴金属粒子１と、この貴金属粒子１を担持する第１の化合物２とからなる複合粒子に関して、その複合粒子のサイズ（複合粒子の平均粒径）Ｄ２と、この複合粒子を内包する第２の化合物３に形成されている細孔の平均細孔径Ｄ３とは、Ｄ２のＤ３に対する比Ｄ２／Ｄ３が、１以上であることが好ましい。Ｄ２／Ｄ３が、１以上であることは、貴金属粒子１と第１の化合物２とからなる複合粒子のユニットの平均粒径Ｄ２が、第２の化合物３に形成されている空隙の平均径Ｄ３よりも大きいことを意味している。Ｄ２／Ｄ３が１以上であることにより、貴金属粒子１と第１の化合物２との複合粒子が、第２の化合物３に形成されている細孔を通して移動することが抑制される。したがって、第２の化合物３による包接効果の低下が抑制される。この効果は発明者らの実験により確認されている。図７は、複合粒子のサイズＤ２と平均細孔径Ｄ３との比Ｄ２／Ｄ３を横軸に、第１の化合物としてのＣｅＯ２の結晶成長比及び排気耐久試験後の貴金属粒子としてのＰｔの表面積を縦軸にして、これらの関係を示すグラフである。図７から、Ｄ２／Ｄ３が１以上である場合に、ＣｅＯ２の結晶成長比が顕著に低下し、すなわち、ＣｅＯ２の焼結が少ないので包接効果が大きく、また、耐久試験後のＰｔの表面積が大きく、すなわち、Ｐｔの凝集が少ないので触媒活性の低下が少ないことが分かる。 Next, regarding the composite particles composed of the noble metal particles 1 and the first compound 2 supporting the noble metal particles 1, the size of the composite particles (average particle diameter of the composite particles) D2 and the first particles enclosing the composite particles The average pore diameter D3 of the pores formed in the compound 3 of No. 2 is preferably such that the ratio D2 / D3 of D2 to D3 is 1 or more. The fact that D2 / D3 is 1 or more means that the average particle diameter D2 of the composite particle unit composed of the noble metal particles 1 and the first compound 2 is the average diameter D3 of the voids formed in the second compound 3. Means greater than. When D2 / D3 is 1 or more, the movement of the composite particles of the noble metal particles 1 and the first compound 2 through the pores formed in the second compound 3 is suppressed. Therefore, a decrease in the inclusion effect due to the second compound 3 is suppressed. This effect has been confirmed by experiments by the inventors. FIG. 7 shows the crystal growth ratio of CeO 2 as the first compound and the surface area of Pt as the noble metal particles after the exhaust durability test, with the ratio D2 / D3 of the composite particle size D2 and the average pore diameter D3 as the horizontal axis. It is a graph which shows these relationships by making ordinate the vertical axis. From FIG. 7, when D2 / D3 is 1 or more, the crystal growth ratio of CeO 2 is remarkably reduced, that is, the inclusion effect is large because there is little sintering of CeO 2 , and Pt after the durability test It can be seen that the surface area of the catalyst is large, that is, the Pt agglomeration is small, so that the catalytic activity is hardly lowered.
次に、本発明の排気ガス浄化用触媒を製造するに際しては、第１の化合物を予め焼結させたのち、貴金属粒子をこの第１の化合物上に担持させる工程と、前記貴金属粒子が担持された第１の化合物を粉砕する工程と、前記粉砕された貴金属担持第１の化合物の周囲に、第２の化合物を形成する工程とを含む方法を用いることができる。 Next, when manufacturing the exhaust gas purifying catalyst of the present invention, the first compound is pre-sintered and then the noble metal particles are supported on the first compound, and the noble metal particles are supported. In addition, a method including a step of pulverizing the first compound and a step of forming a second compound around the pulverized noble metal-supported first compound can be used.
第１の化合物は、前述のとおり、希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む複合物よりなるものであって、このような第１の化合物を予め焼結することにより、この希土類元素と、アルカリ金属ないしはアルカリ土類金属との複合化を促進させ、かつ、焼結を抑制させることができる。第１の化合物を焼結後に貴金属粒子を担持させることにより、貴金属粒子の埋没を起こすことなく、貴金属粒子がナノ粒子状態を維持することが可能となる。貴金属粒子が担持された第１の化合物は粉砕されることにより、後工程で第２の化合物により内包された区画（ユニット）内の貴金属量を所定の範囲に調整することが可能となる。粉砕された貴金属粒子担持第１の化合物に第２の化合物を形成することより、貴金属粒子担持第１の化合物を第２の化合物で内包して、第２の化合物により隔てられた区画内に含まれるようにする。これらの工程を行うときの条件は、適切な条件に行うことができる。また、これらの工程以外の工程については、常法に従い本発明の排気ガス浄化用触媒を製造することができる。 As described above, the first compound is composed of a composite containing a rare earth element and at least one metal selected from an alkali metal and an alkaline earth metal. By sintering, the complexing of the rare earth element with an alkali metal or alkaline earth metal can be promoted and sintering can be suppressed. By supporting the noble metal particles after sintering the first compound, the noble metal particles can maintain the nanoparticle state without causing the noble metal particles to be buried. By pulverizing the first compound on which the noble metal particles are supported, it becomes possible to adjust the amount of the noble metal in the compartment (unit) encapsulated by the second compound in a later step to a predetermined range. By forming the second compound in the pulverized noble metal particle-supporting first compound, the noble metal particle-supporting first compound is included in the second compound and included in the compartment separated by the second compound To be. The conditions for performing these steps can be set to appropriate conditions. Moreover, about processes other than these processes, the exhaust gas purification catalyst of this invention can be manufactured in accordance with a conventional method.
このようにして得られた排気ガス浄化用触媒の粉末は、スラリ状にされ、このスラリーを耐火性無機担体である触媒ハニカム基体の内壁表面にコーティングされ、排気ガスの浄化のために供される。 The exhaust gas purification catalyst powder obtained in this way is made into a slurry, and this slurry is coated on the inner wall surface of the catalyst honeycomb substrate, which is a refractory inorganic carrier, and used for exhaust gas purification. .
以下、本発明を実施例に基づいて具体的に説明する。 Hereinafter, the present invention will be specifically described based on examples.
［触媒の製造］
表１及び表２に示す実施例１〜２７、比較例１〜５の排気ガス浄化用触媒を、以下のとおりにして製造した。表１は実施例１〜２７、比較例１〜５の排気ガス浄化用触媒における貴金属粒子及び第１の化合物を示したものであり、表２は実施例１〜２７、比較例１〜５の排気ガス浄化用触媒における第２の化合物、触媒粉末特性及び触媒性能を示したものである。
Exhaust gas purifying catalysts of Examples 1 to 27 and Comparative Examples 1 to 5 shown in Tables 1 and 2 were produced as follows. Table 1 shows the precious metal particles and the first compound in the exhaust gas purifying catalysts of Examples 1 to 27 and Comparative Examples 1 to 5, and Table 2 shows Examples 1 to 27 and Comparative Examples 1 to 5. The 2nd compound in an exhaust gas purification catalyst, the catalyst powder characteristic, and the catalyst performance are shown.
〔実施例１〕
＜粉末調製工程＞
ナノ酸化Ce微粒子粉末に、酸化Ceに対して、5mol%となるように、酢酸Rbを含浸担持した後、乾燥し、更に、600℃で3時間、空気雰囲気中で焼成し、実施例1の第１の化合物を得た。この粉末をXRDにて測定し、シェラーの式により算出した際の結晶子径は表1に示すとおりであった。
[Example 1]
<Powder preparation process>
The nano-oxidized Ce fine particle powder was impregnated and supported with Rb acetate so as to be 5 mol% with respect to the oxidized Ce, and then dried and further baked in an air atmosphere at 600 ° C. for 3 hours. A first compound was obtained. This powder was measured by XRD, and the crystallite diameter when calculated by Scherrer's formula was as shown in Table 1.
上記工程にて得られた粉末に対し、貴金属担持濃度が0.5wt%となるように、テトラアンミンPd水溶液を担持し、乾燥後、400℃で1時間、空気中で焼成した。 The powder obtained in the above step was loaded with an aqueous tetraammine Pd solution so that the noble metal loading concentration was 0.5 wt%, dried, and calcined in air at 400 ° C. for 1 hour.
このPd（0.5wt%）／CeRbOx粉末を、水溶液中で粉砕し、平均粒子径310nmの分散スラリを得た。 This Pd (0.5 wt%) / CeRbO x powder was pulverized in an aqueous solution to obtain a dispersed slurry having an average particle diameter of 310 nm.
一方、ベーマイト粉末を分散させた分散スラリに、上記で得た貴金属担持第１の化合物分散スラリを投入し、乾燥した後、550℃で3時間、空気中で焼成することで、実施例1の触媒粉末を得た。 On the other hand, the precious metal-supported first compound-dispersed slurry obtained above was added to the dispersed slurry in which boehmite powder was dispersed, dried, and then fired in air at 550 ° C. for 3 hours. A catalyst powder was obtained.
なお、このときに用いたベーマイト（第２の化合物の前駆体）は、同条件でベーマイトのみを乾燥・焼成した際の、N2吸着法により算出した平均空隙径は22nmであった。したがって、上記貴金属含有粉末の第２の化合物の空隙径もこれに準じるものと考えることができる。 The boehmite (precursor of the second compound) used at this time had an average pore diameter calculated by the N 2 adsorption method of 22 nm when only boehmite was dried and calcined under the same conditions. Therefore, it can be considered that the void diameter of the second compound of the noble metal-containing powder is similar to this.
＜ハニカム基体へのコーティング工程＞
所定量の上記粉末と、所定量のベーマイトを磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi、6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、実施例1の触媒ハニカム基体を得た。このときの触媒ハニカム1Lあたりの貴金属量は、0.5ｇ/L−ハニカムであった。
<Coating process on honeycomb substrate>
A predetermined amount of the above powder and a predetermined amount of boehmite are put into a magnetic pot, and after pulverizing the average particle size to 3 μm, it is applied to a 0.119 L (400 cpsi, 6 mil) cordierite honeycomb substrate, and an excess slurry is applied. After removing it with an air stream, it was dried at 130 ° C. and fired at 400 ° C. for 1 hour in an air atmosphere to obtain a catalyst honeycomb substrate of Example 1. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔実施例２〕
実施例１における上記粉末調製工程中の酢酸Rbを酢酸Baにした以外は同様にして、実施例2の触媒ハニカムを得た。
[Example 2]
A catalyst honeycomb of Example 2 was obtained in the same manner except that Rb acetate in the powder preparation step in Example 1 was changed to Ba acetate.
〔実施例３〕
実施例1における上記粉末調製工程中の酢酸Rbを酢酸Csにした以外は同様にして、実施例3の触媒ハニカムを得た。
Example 3
A catalyst honeycomb of Example 3 was obtained in the same manner except that Rb acetate in the powder preparation step in Example 1 was changed to Cs acetate.
〔実施例４〕
実施例1における上記粉末調製工程中の酢酸Rbを酢酸Mgにし、Pd担持CeMgOx粉末分散スラリの平均粒子径を330nmにした以外は同様にして、実施例4の触媒ハニカムを得た。
Example 4
A catalyst honeycomb of Example 4 was obtained in the same manner except that Rb acetate in the powder preparation step in Example 1 was changed to Mg acetate and the average particle size of the Pd-supported CeMgO x powder dispersion slurry was changed to 330 nm.
〔実施例５〕
実施例1における上記粉末調製工程中のナノ酸化Ce粉末をNd2O3とし、酢酸Rbを酢酸Mgにし、Pd担持NdMgOx粉末分散スラリの平均粒子径を290nmにした以外は同様にして、実施例5の触媒ハニカムを得た。
Example 5
In the same manner as in Example 1, except that the nano-oxidized Ce powder in the above powder preparation step was Nd 2 O 3 , Rb acetate was Mg acetate, and the average particle size of the Pd-supported NdMgO x powder dispersion slurry was 290 nm. The catalyst honeycomb of Example 5 was obtained.
〔実施例６〕
実施例1における上記粉末調整工程中のナノ酸化Ce粉末をPr2O3とし、酢酸Rbを酢酸Caにし、Pd担持PrCaOx粉末分散スラリの平均粒子径を310nmにした以外は同様にして、実施例6の触媒ハニカムを得た。
Example 6
In the same manner as in Example 1, except that the nano-oxidized Ce powder in the powder preparation step was Pr 2 O 3 , acetate Rb was Ca acetate, and the average particle size of the Pd-supported PrCaO x powder dispersion slurry was 310 nm. The catalyst honeycomb of Example 6 was obtained.
〔実施例７〕
実施例1における上記粉末調製工程中のナノ酸化Ce粉末を、La5モル％担持CeO2となるように硝酸Laを含浸担持、乾燥、400℃で1時間空気気流中で焼成した後、次いで、所定量の酢酸Mgを含浸担持、乾燥、焼成し、貴金属を担持し、同様の焼成処理を行った。次に、このようにして得られた粉末を粉砕により微細化する工程において、平均粒子径310nmとした以外は同様にして、実施例７の触媒ハニカムを得た。
Example 7
The nano-oxidized Ce powder in the above powder preparation step in Example 1 was impregnated with La nitrate so as to become LaO 5 mol% -supported CeO 2 , dried, and calcined at 400 ° C. for 1 hour in an air stream. A fixed amount of Mg acetate was impregnated, dried, and fired, a precious metal was supported, and the same firing treatment was performed. Next, a catalyst honeycomb of Example 7 was obtained in the same manner except that the average particle diameter was 310 nm in the step of finely pulverizing the powder thus obtained.
〔実施例８〕
実施例4における上記粉末調製工程中の第１の化合物原料を600℃で3時間焼成する工程を、800℃で3時間とした以外は同様にして、実施例8の触媒ハニカムを得た。
Example 8
A catalyst honeycomb of Example 8 was obtained in the same manner except that the step of firing the first compound raw material in the powder preparation step of Example 4 at 600 ° C. for 3 hours was performed at 800 ° C. for 3 hours.
〔実施例９〕
実施例４における上記粉末調製工程中の第１の化合物原料を600℃で3時間焼成する工程を、1000℃で3時間とし、スラリの粉砕工程で、平均粒子径を340nmとした以外は同様にして、実施例9の触媒ハニカムを得た。
Example 9
The step of calcining the first compound raw material in the powder preparation step in Example 4 at 600 ° C. for 3 hours was performed at 1000 ° C. for 3 hours, and the slurry was pulverized in the same manner except that the average particle size was 340 nm. Thus, a catalyst honeycomb of Example 9 was obtained.
〔実施例１０〕
実施例４における上記粉末調製工程中の第１の化合物原料を600℃で3時間焼成する工程を、1100℃で3時間とし、スラリの粉砕工程で、平均粒子径を350nmとした以外は同様にして、実施例１０の触媒ハニカムを得た。
Example 10
The same procedure as in Example 4 except that the first compound raw material in the powder preparation step was calcined at 600 ° C. for 3 hours at 1100 ° C. for 3 hours, and the average particle size was 350 nm in the slurry grinding step. Thus, a catalyst honeycomb of Example 10 was obtained.
〔実施例１１〕
実施例９における粉末製造工程中のナノ酸化CeをZr10モル％含有CeO2とし、スラリ粉砕工程で、平均粒子径を330nmとした以外は同様にして、実施例１１の触媒ハニカムを得た。
Example 11
A catalyst honeycomb of Example 11 was obtained in the same manner except that the nano-oxidized Ce in the powder production process in Example 9 was changed to CeO 2 containing 10 mol% of Zr and the average particle diameter was changed to 330 nm in the slurry grinding process.
〔実施例１２〕
実施例１１におけるテトラアンミンPdをテトラアンミンPtとした以外は同様にして、実施例１２の触媒ハニカムを得た。
Example 12
A catalyst honeycomb of Example 12 was obtained in the same manner except that tetraammine Pd in Example 11 was changed to tetraammine Pt.
〔実施例１３〕
実施例９の上記粉末調製工程中のテトラアンミンPdを硝酸Rhとし、平均粒子径を180nmとした以外は同様にして、実施例１３の触媒ハニカムを得た。
Example 13
A catalyst honeycomb of Example 13 was obtained in the same manner except that tetraammine Pd in the powder preparation step of Example 9 was Rh nitrate and the average particle size was 180 nm.
〔実施例１４〕
実施例１１におけるCeZrMgOxに対するPdの担持濃度を1.0％とし、スラリ平均粒子径を155nmとし、触媒ハニカムに塗布時、ハニカム1Lあたりの貴金属量が同等となるように、γアルミナを混ぜ、ハニカムに塗布した以外は同様にして、実施例１４の触媒ハニカムを得た。
Example 14
In Example 11, the supported concentration of Pd with respect to CeZrMgO x was 1.0%, the average particle diameter of the slurry was 155 nm, and when applied to the catalyst honeycomb, γ alumina was mixed so that the amount of noble metal per 1 L of honeycomb was equal, A catalyst honeycomb of Example 14 was obtained in the same manner except that the coating was applied.
〔実施例１５〕
実施例４におけるCeMgOxをCeNaOxとした以外は同様にして、実施例１５の触媒ハニカムを得た。
Example 15
A catalyst honeycomb of Example 15 was obtained in the same manner except that CeMgO x was changed to CeNaO x in Example 4.
〔実施例１６〕
実施例４におけるCeMgOxをCeKOxとした以外は同様にして、実施例１６の触媒ハニカムを得た。
Example 16
Except that the CeMgO x in Example 4 was CeKO x in the same manner to obtain a catalyst honeycomb of Example 16.
〔実施例１７〕
実施例４におけるCeMgOxをCeSrOxとした以外は同様にして、実施例１７の触媒ハニカムを得た。
Example 17
A catalyst honeycomb of Example 17 was obtained in the same manner except that CeMgO x was changed to CeSrO x in Example 4.
〔実施例１８〕
＜粉末調製工程＞
ナノ酸化Ce微粒子粉末に、酸化Ceに対して、5mol%となるように、酢酸Mgを含浸担持した後、乾燥し、更に、400℃で3時間、空気雰囲気で焼成し、実施例１８の第１の化合物を得た。この粉末をXRDにて測定し、シェラーの式により算出した際の結晶子径は表1に示すとおりであった。
Example 18
<Powder preparation process>
The nano-oxidized Ce fine particle powder was impregnated and supported with Mg acetate so as to be 5 mol% with respect to the oxidized Ce, and then dried and further baked in an air atmosphere at 400 ° C. for 3 hours. 1 compound was obtained. This powder was measured by XRD, and the crystallite diameter when calculated by Scherrer's formula was as shown in Table 1.
上記工程にて得られた粉末に対し、貴金属担持濃度が0.5wt%となるように、テトラアンミンPd水溶液を担持し、乾燥後、400℃で1時間、空気中で焼成した。 The powder obtained in the above step was loaded with an aqueous tetraammine Pd solution so that the noble metal loading concentration was 0.5 wt%, dried, and calcined in air at 400 ° C. for 1 hour.
このPd（0.5wt%）／CeMgOx粉末を、水溶液中で、粉砕し、平均粒子径330nmの分散スラリを得た。 This Pd (0.5 wt%) / CeMgO x powder was pulverized in an aqueous solution to obtain a dispersed slurry having an average particle size of 330 nm.
一方、ベーマイト粉末を分散させた分散スラリに、上記で得た貴金属担持第１の化合物分散スラリを投入し、乾燥した後、550℃で3時間、空気中で焼成することで、実施例１８の触媒粉末を得た。 On the other hand, the noble metal-supported first compound-dispersed slurry obtained above was added to the dispersed slurry in which boehmite powder was dispersed, dried, and then calcined in air at 550 ° C. for 3 hours. A catalyst powder was obtained.
なお、このときに用いたベーマイト（第２の化合物の前駆体）は、同条件でベーマイトのみを乾燥・焼成した際の、N2吸着法により算出した平均空隙径は22nmであった。したがって、上記貴金属含有粉末の第２の化合物の空隙径もこれに準じるものと考えることができる。 The boehmite (precursor of the second compound) used at this time had an average pore diameter calculated by the N 2 adsorption method of 22 nm when only boehmite was dried and calcined under the same conditions. Therefore, it can be considered that the void diameter of the second compound of the noble metal-containing powder is similar to this.
＜ハニカム基体へのコーティング工程＞
所定量の上記粉末と、所定量のベーマイトを磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi、6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、実施例1８の触媒ハニカム基体を得た。このときの触媒ハニカム1Lあたりの貴金属量は、0.5ｇ/L−ハニカムであった。
<Coating process on honeycomb substrate>
A predetermined amount of the above powder and a predetermined amount of boehmite are put into a magnetic pot, and after pulverizing the average particle size to 3 μm, it is applied to a 0.119 L (400 cpsi, 6 mil) cordierite honeycomb substrate, and an excess slurry is applied. After removing it with an air stream, it was dried at 130 ° C. and fired at 400 ° C. for 1 hour in an air atmosphere to obtain a catalyst honeycomb substrate of Example 18. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔実施例１９〕
＜粉末調製工程＞
ナノ酸化Zr粉末に、酢酸Ceを15mol%となるように含浸担持後、乾燥し、更に、900℃で3時間、空気雰囲気で焼成し、実施例１９の第１の化合物を得た。この粉末をXRDにて測定し、シェラーの式により算出した際の結晶子径は表1に示すとおりであった。
Example 19
<Powder preparation process>
The nano-oxidized Zr powder was impregnated and supported with Ce acetate at 15 mol%, dried, and then calcined at 900 ° C. for 3 hours in an air atmosphere to obtain the first compound of Example 19. This powder was measured by XRD, and the crystallite diameter when calculated by Scherrer's formula was as shown in Table 1.
上記工程にて得られた粉末に対し、貴金属担持濃度が0.5wt%となるように、ジニトロジアミンPd水溶液を担持し、乾燥後、400℃で1時間、空気中で焼成した。 The powder obtained in the above step was loaded with an aqueous dinitrodiamine Pd solution so that the noble metal loading concentration was 0.5 wt%, dried, and calcined in air at 400 ° C. for 1 hour.
このPd（0.5wt%)/ZrCeOx粉末を、水溶液中で、粉砕し、平均粒子径310nmの分散スラリを得た。 This Pd (0.5 wt%) / ZrCeOx powder was pulverized in an aqueous solution to obtain a dispersed slurry having an average particle diameter of 310 nm.
一方、ベーマイト粉末を分散させた分散スラリに、上記で得た貴金属担持第１の化合物分散スラリを投入し、乾燥した後、550℃で3時間、空気中で焼成することで、実施例１９の触媒粉末を得た。 On the other hand, the precious metal-supported first compound-dispersed slurry obtained above was added to the dispersed slurry in which boehmite powder was dispersed, dried, and then calcined in air at 550 ° C. for 3 hours. A catalyst powder was obtained.
なお、このときに用いたベーマイト（第２の化合物の前駆体）は、同条件でベーマイトのみを乾燥・焼成した際の、N2吸着法により算出した平均空隙径は31nmであった。したがって、上記貴金属含有粉末の第２の化合物の空隙径もこれに準じるものと考えることができる。 The boehmite (precursor of the second compound) used at this time had an average pore diameter calculated by the N 2 adsorption method of 31 nm when only boehmite was dried and fired under the same conditions. Therefore, it can be considered that the void diameter of the second compound of the noble metal-containing powder is similar to this.
また、この時に得た実施例１９の粉末の細孔容積は表２に示す値であった。 Further, the pore volume of the powder of Example 19 obtained at this time was a value shown in Table 2.
＜ハニカム基体へのコーティング工程＞
所定量の上記粉末と、所定量のベーマイトを磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi,6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、実施例１９の触媒ハニカムを得た。このときの触媒ハニカム1Lあたりの貴金属量は、0.5ｇ/L−ハニカムであった。
<Coating process on honeycomb substrate>
A predetermined amount of the above powder and a predetermined amount of boehmite are put into a magnetic pot, and after pulverizing to an average particle diameter of 3 μm, it is applied to a 0.119 L (400 cpsi, 6 mil) cordierite honeycomb substrate, and an excess slurry is applied. After removal with an air stream, drying at 130 ° C. and firing at 400 ° C. for 1 hour in an air atmosphere gave a catalyst honeycomb of Example 19. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔実施例２０〕
実施例１９の酸化ZrへのCe添加の代わりに、表1に示すモル組成となるよう所定量の硝酸Ceと硝酸Laを添加し、ベーマイト粉末を分散させたスラリに硝酸Ceを投入し、平均細孔径が28nmのベーマイトを用いた以外は同様にして、実施例２０の触媒ハニカムを得た。
Example 20
Instead of adding Ce to Zr oxide in Example 19, a predetermined amount of Ce nitrate and La nitrate was added so as to have the molar composition shown in Table 1, and Ce nitrate was added to the slurry in which boehmite powder was dispersed. A catalyst honeycomb of Example 20 was obtained in the same manner except that boehmite having a pore diameter of 28 nm was used.
〔実施例２１〕
実施例１９の酸化ZrへのCe添加の代わりに、表1に示すモル組成となるよう所定量の硝酸Ceと硝酸Ndを添加し、ベーマイト粉末を分散させたスラリに硝酸Ceと硝酸Zr及び硝酸Laを投入し、平均細孔径が25nmのベーマイトを用いた以外は同様にして、実施例２１の触媒ハニカムを得た。
Example 21
Instead of Ce added to the Zr oxide in Example 19, was added a predetermined amount of Ce nitrate and nitric acid Nd to be a molar composition shown in Table 1, and nitric C e Zr nitrate in a slurry prepared by dispersing boehmite powder A catalyst honeycomb of Example 21 was obtained in the same manner except that La nitrate was added and boehmite having an average pore diameter of 25 nm was used.
〔実施例２２〕
実施例１９の酸化ZrへのCe添加の代わりに、表1に示すモル組成となるよう所定量の硝酸Ceと硝酸Laを添加し、ベーマイト粉末を分散させたスラリに硝酸Ceと硝酸Zr、硝酸La及び硝酸Baを投入し、平均細孔径が25nmのベーマイトを用いた以外は同様にして、実施例２２の触媒ハニカムを得た。
[Example 22]
Instead of Ce addition to Zr oxide of Example 19, a predetermined amount of Ce nitrate and La nitrate was added so as to have the molar composition shown in Table 1, and Ce nitrate, Zr nitrate, and nitrate were added to the slurry in which boehmite powder was dispersed. A catalyst honeycomb of Example 22 was obtained in the same manner except that La and Ba nitrate were used and boehmite having an average pore diameter of 25 nm was used.
〔実施例２３〕
実施例１９の酸化ZrへのCe添加の代わりに、表1に示すモル組成となるよう所定量の硝酸Ceと硝酸Prを添加し、ベーマイト粉末を分散させたスラリに硝酸Ceと硝酸Zr、硝酸La及び硝酸Baを投入し、平均細孔径が25nmのベーマイトを用いた以外は同様にして、実施例２３の触媒ハニカムを得た。
Example 23
Instead of adding Ce to the oxidized Zr of Example 19, a predetermined amount of Ce nitrate and Pr nitrate were added so as to have the molar composition shown in Table 1, and Ce nitrate, Zr nitrate, and nitrate were added to the slurry in which boehmite powder was dispersed. A catalyst honeycomb of Example 23 was obtained in the same manner except that La and Ba nitrate were used and boehmite having an average pore diameter of 25 nm was used.
〔実施例２４〕
実施例１９の酸化ZrへのCe添加の代わりに、表1に示すモル組成となるよう所定量の硝酸Ceと硝酸Prを添加し、ベーマイト粉末を分散させたスラリに硝酸Ceと硝酸Zrを投入し、平均細孔径が25nmのベーマイトを用い、ジニトロジアミンPdを硝酸Rhとした以外は同様にして、実施例２４の触媒ハニカムを得た。
Example 24
Instead of adding Ce to the oxidized Zr of Example 19, a predetermined amount of Ce nitrate and Pr nitrate were added so as to have the molar composition shown in Table 1, and Ce nitrate and Zr nitrate were added to the slurry in which boehmite powder was dispersed. A catalyst honeycomb of Example 24 was obtained in the same manner except that boehmite having an average pore diameter of 25 nm was used and dinitrodiamine Pd was changed to Rh nitrate.
〔実施例２５〕
上記実施例4のベーマイト粉末を分散させたスラリに、表1に示す組成となるよう、所定量の硝酸Ceと硝酸Zrおよび硝酸Laを投入し、平均細孔径が24nmのベーマイトを用いた以外は同様にして、実施例２５の触媒ハニカムを得た。
Example 25
A slurry in which the boehmite powder of Example 4 was dispersed was charged with a predetermined amount of Ce nitrate, Zr nitrate and La nitrate so as to have the composition shown in Table 1, except that boehmite having an average pore diameter of 24 nm was used. Similarly, a catalyst honeycomb of Example 25 was obtained.
〔実施例２６〕
実施例１９の酸化ＺｒへのＣｅ添加の代わりに、表１に示すモル組成となるよう所定量の硝酸Ｃｅと硝酸Yを添加した以外は実施例１９と同様にして、実施例２６の触媒ハニカムを得た。
Example 26
Instead of Ce addition to Zr oxide Zr in Example 19, the catalyst honeycomb of Example 26 was made in the same manner as Example 19 except that predetermined amounts of Ce nitrate and Y nitrate were added so as to have the molar composition shown in Table 1. Got.
〔実施例２７〕
実施例２４の酸化ＺｒへのＣｅおよびPr添加の代わりに、表1に示すモル組成となるよう所定量の硝酸Ｃｅと硝酸Yを添加した以外は実施例２４と同様にして、実施例２７の触媒ハニカムを得た。
Example 27
Instead of adding Ce and Pr to the Zr oxide Zr in Example 24, the same procedure as in Example 24 was performed except that a predetermined amount of Ce nitrate and Y nitrate was added so as to have the molar composition shown in Table 1. A catalyst honeycomb was obtained.
〔比較例１〕
比較例１は、触媒粉末における第１の化合物が、実施例１〜２５とは異なり、希土類元素（Ｃｅ）のみである例である。
[Comparative Example 1]
Comparative Example 1 is an example in which the first compound in the catalyst powder is different from Examples 1 to 25 and is only a rare earth element (Ce).
＜粉末調製工程＞
ナノ酸化Ce微粒子粉末に、貴金属担持濃度が0.5wt%となるように、ジニトロジアミンPd水溶液を担持し、乾燥後、400℃で1時間、空気中で焼成した。
<Powder preparation process>
The nano-oxidized Ce fine particle powder was loaded with an aqueous dinitrodiamine Pd solution so that the noble metal loading concentration was 0.5 wt%, dried, and calcined in air at 400 ° C. for 1 hour.
このPd（0.5wt%）／CeO2粉末を、水溶液中で、粉砕し、平均粒子径310nmの分散スラリを得た。 This Pd (0.5 wt%) / CeO 2 powder was pulverized in an aqueous solution to obtain a dispersed slurry having an average particle diameter of 310 nm.
一方、ベーマイト粉末を分散させた分散スラリに、上記で得た粉末分散スラリを投入し、乾燥した後、550℃×3Hr、Air中で焼成することで、比較例１の触媒粉末を得た。 On the other hand, the powder-dispersed slurry obtained above was put into a dispersed slurry in which boehmite powder was dispersed, dried, and then fired in air at 550 ° C. × 3 Hr to obtain a catalyst powder of Comparative Example 1.
尚、このときに用いたベーマイト（第２の化合物の前駆体）は、同条件でベーマイトのみを乾燥・焼成した際の、N2吸着法により算出した平均空隙径は22nmであった。したがって、上記貴金属含有粉末の第２の化合物の空隙径もこれに準じるものと考えることができる。 The boehmite (precursor of the second compound) used at this time had an average pore diameter calculated by the N 2 adsorption method of 22 nm when only boehmite was dried and fired under the same conditions. Therefore, it can be considered that the void diameter of the second compound of the noble metal-containing powder is similar to this.
＜ハニカム基体へのコーティング工程＞
所定量の上記粉末と、所定量のベーマイトを磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi、6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、比較例1の触媒ハニカム基体を得た。このときの触媒ハニカム1Lあたりの貴金属量は、0.5ｇ/L−ハニカムであった。
<Coating process on honeycomb substrate>
A predetermined amount of the above powder and a predetermined amount of boehmite are put into a magnetic pot, and after pulverizing the average particle size to 3 μm, it is applied to a 0.119 L (400 cpsi, 6 mil) cordierite honeycomb substrate, and an excess slurry is applied. After removal with an air stream, drying at 130 ° C. and firing at 400 ° C. for 1 hour in an air atmosphere gave a catalyst honeycomb substrate of Comparative Example 1. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔比較例２〕
比較例２は、触媒粉末における第１の化合物が、実施例１〜２５とは異なり、希土類元素（Ｃｅ−Ｚｒ（Ｃｅリッチ））のみである例である。
[Comparative Example 2]
Comparative Example 2 is an example in which the first compound in the catalyst powder is only a rare earth element (Ce—Zr (Ce-rich)) unlike Examples 1 to 25.
＜粉末調製工程＞
Zr10モル％含有ナノ酸化Ce微粒子粉末に、貴金属担持濃度が1.0wt%となるように、ジニトロジアミンPd水溶液を担持し、乾燥後、400℃で3時間、空気中で焼成した。このPd（1.0wt%）／CeZrOx粉末を、水溶液中で、粉砕し、平均粒子径155nmの分散スラリを得た。
<Powder preparation process>
A dinitrodiamine Pd aqueous solution was supported on nano-oxidized Ce fine particle powder containing 10 mol% of Zr so that the noble metal support concentration was 1.0 wt%, dried, and calcined in air at 400 ° C. for 3 hours. This Pd (1.0 wt%) / CeZrO x powder was pulverized in an aqueous solution to obtain a dispersed slurry having an average particle diameter of 155 nm.
一方、ベーマイト粉末を分散させた分散スラリに、上記で得た粉末分散スラリを投入し、乾燥した後、550℃で3時間、空気中で焼成することで、比較例２の触媒粉末を得た。 On the other hand, the powder dispersion slurry obtained above was put into a dispersion slurry in which boehmite powder was dispersed, dried, and then fired in air at 550 ° C. for 3 hours to obtain a catalyst powder of Comparative Example 2. .
なお、このときに用いたベーマイト（第２の化合物の前駆体）は、同条件でベーマイトのみを乾燥・焼成した際の、N2吸着法により算出した平均空隙径は22nmであった。したがって、上記貴金属含有粉末の第２の化合物の空隙径もこれに準じるものと考えることができる。 The boehmite (precursor of the second compound) used at this time had an average pore diameter calculated by the N 2 adsorption method of 22 nm when only boehmite was dried and calcined under the same conditions. Therefore, it can be considered that the void diameter of the second compound of the noble metal-containing powder is similar to this.
＜ハニカム基体へのコーティング工程＞
所定量の上記粉末と、γアルミナ及び所定量のベーマイトを磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi、6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、比較例２の触媒ハニカム基体を得た。このときの触媒ハニカム1Lあたりの貴金属量は、0.5ｇ/L−ハニカムであった。
<Coating process on honeycomb substrate>
A predetermined amount of the above powder, γ-alumina and a predetermined amount of boehmite are put into a magnetic pot, and after pulverizing the average particle size to 3 μm, it is applied to a 0.119 L (400 cpsi, 6 mil) cordierite honeycomb substrate, Excess slurry was removed with an air stream, dried at 130 ° C., and fired at 400 ° C. for 1 hour in an air atmosphere to obtain a catalyst honeycomb substrate of Comparative Example 2. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔比較例３〕
比較例３は、触媒粉末における第１の化合物が、実施例１〜２５とは異なり、希土類元素（Ｃｅ−Ｚｒ／アルミナ）のみであり、また、第２の化合物を具備していない例である。
[Comparative Example 3]
Comparative Example 3 is an example in which the first compound in the catalyst powder is only a rare earth element (Ce—Zr / alumina), unlike Examples 1 to 25, and does not include the second compound. .
γアルミナにCeとして10モル％、Zrとして3モル％となるように、硝酸Ceと硝酸ジルコニルとを含浸させた後、130℃で乾燥後、400℃で3時間、空気中で焼成した。 The γ-alumina was impregnated with Ce nitrate and zirconyl nitrate so as to be 10 mol% as Ce and 3 mol% as Zr, dried at 130 ° C., and calcined at 400 ° C. for 3 hours in air.
次いで、この粉末にジニトロジアミンPdをPd担持濃度として、0.5ｗｔ％となるように担持し、乾燥後、400℃で1時間焼成した。 Next, dinitrodiamine Pd was supported on this powder so that the concentration of Pd supported was 0.5 wt%, dried, and calcined at 400 ° C. for 1 hour.
この貴金属担持粉末と、γアルミナ及び所定量のベーマイトと、硝酸を磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi、6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、比較例3の触媒ハニカム基体を得た。このときの触媒ハニカム1Lあたりの貴金属量は0.5ｇ/L−ハニカムであった。 This noble metal-supported powder, γ-alumina, a predetermined amount of boehmite, and nitric acid are put into a magnetic pot, and the average particle size is pulverized to 3 μm. The excess slurry was removed with an air stream, dried at 130 ° C., and fired at 400 ° C. for 1 hour in an air atmosphere to obtain a catalyst honeycomb substrate of Comparative Example 3. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔比較例４〕
比較例3の担持貴金属塩をジニトロジアミンPtとした以外は同様にして、比較例４の触媒ハニカム基体を得た。この時の触媒ハニカム1Lあたりの貴金属量は0.5ｇ/L−ハニカムであった。
[Comparative Example 4]
A catalyst honeycomb substrate of Comparative Example 4 was obtained in the same manner except that the supported noble metal salt of Comparative Example 3 was dinitrodiamine Pt. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
〔比較例５〕
比較例５は、触媒粉末における第１の化合物が、実施例１〜２５とは異なり、Ｚｒ／アルミナのみである例である。
[Comparative Example 5]
Comparative Example 5 is an example in which the first compound in the catalyst powder is different from Examples 1 to 25 and is only Zr / alumina.
γアルミナにZrとして3モル％となるように、硝酸ジルコニルを含浸させた後、130℃で乾燥後、400℃で焼成した。次いで、この粉末に硝酸Rh水溶液をRh担持濃度として、0.5ｗｔ％となるように担持し、乾燥後、400℃で1時間焼成した。 Zirconyl nitrate was impregnated in γ-alumina so as to be 3 mol% as Zr, dried at 130 ° C., and calcined at 400 ° C. Then, the Rh-supporting concentration Rh nitrate aqueous solution to the powder, carried as a 0.5 wt%, after drying, was calcined 1 hour at 400 ° C..
この貴金属担持粉末と、γアルミナ及び所定量のベーマイトと、硝酸を磁性ポットに投入し、平均粒子径を3μｍまで粉砕した後、0.119Lの（400cpsi、6mil）のコーディエライト製ハニカム基体に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、比較例5の触媒ハニカム基体を得た。このときの触媒ハニカム1Lあたりの貴金属量は0.5ｇ/L−ハニカムであった。 This noble metal-supported powder, γ-alumina, a predetermined amount of boehmite, and nitric acid are put into a magnetic pot, and the average particle size is pulverized to 3 μm. The excess slurry was removed with an air stream, dried at 130 ° C., and fired at 400 ° C. for 1 hour in an air atmosphere to obtain a catalyst honeycomb substrate of Comparative Example 5. At this time, the amount of precious metal per 1 L of the catalyst honeycomb was 0.5 g / L-honeycomb.
［耐久試験］
以上のようにして製造された実施例１〜２５、比較例１〜５の各触媒ハニカム基体を、日産自動車製Ｖ型６気筒エンジン（排気量３．５Ｌ（ＭＰｉ））の排気系に装着し、入口温度を９００［℃］として３０時間エンジンを稼働させる耐久試験を行った。
[An endurance test]
The catalyst honeycomb substrates of Examples 1 to 25 and Comparative Examples 1 to 5 manufactured as described above are mounted on the exhaust system of a Nissan V-type 6-cylinder engine (displacement 3.5 L (MPi)). Then, an endurance test was performed in which the engine was operated for 30 hours at an inlet temperature of 900 [° C.].
［早期活性化試験］
上記の耐久試験を行った後の各触媒ハニカム基体を、模擬排気ガス流通装置に組み込み、以下の表３に示す組成の模擬排気ガスを流通させ、１１０［℃］から５００［℃］まで昇温速度１０℃／分で昇温し、入口側及び出口側のＨＣ濃度からＨＣの転化率が５０％になる温度を求め、低温活性化の指標とした。
Each catalyst honeycomb substrate after the endurance test was conducted was incorporated into a simulated exhaust gas circulation device, and simulated exhaust gas having the composition shown in Table 3 below was circulated to raise the temperature from 110 [° C.] to 500 [° C.]. The temperature was raised at a rate of 10 ° C./min, and the temperature at which the conversion rate of HC was 50% was determined from the HC concentrations on the inlet side and outlet side, and used as an index for low-temperature activation.
＜貴金属粒子凝集状態の確認＞
上記耐久試験後の貴金属粒子の凝集状態を調べるために、触媒ハニカム基体から触媒粉末を採取し、ＴＥＭにより観察した。用いたＴＥＭは、電界放出形透過型電子顕微鏡（日立製作所ＨＦ−２０００）であり、付属装置としてＥＤＸ分析装置（Ｋｅｖｅｘ製ＳＩＧＭＡ）が付属されているものである。
<Confirmation of noble metal particle aggregation state>
In order to examine the aggregation state of the noble metal particles after the durability test, a catalyst powder was collected from the catalyst honeycomb substrate and observed by TEM. The TEM used is a field emission transmission electron microscope (Hitachi HF-2000), and an EDX analyzer (SIGMA manufactured by Kevex) is attached as an attached device.
〔試験結果〕
これらの試験結果を表２に併記した。
〔Test results〕
These test results are also shown in Table 2.
表２から明らかなように、実施例１〜２７の触媒粉末では、耐久試験後においても、貴金属の平均粒子径が小さいままで維持されており、そのため、低温活性化触媒性能に優れていた。特に、Ｄ１に対するＤ２の比Ｄ２／Ｄ１が１≦Ｄ２／Ｄ１≦５０の範囲にある実施例１〜１７、１９〜２５は、実施例１８よりも低温活性化触媒性能に優れていた。また、ＴＥＭによる貴金属粒子の観察によっても、凝集していないことが確認できた。一例として実施例９の顕微鏡組織写真は、図４に示したとおりである。 As is clear from Table 2, the catalyst powders of Examples 1 to 27 were maintained with a small average particle diameter of the noble metal even after the endurance test, and thus were excellent in low-temperature activated catalyst performance. In particular, Examples 1 to 17 and 19 to 25 in which the ratio D2 / D1 of D2 to D1 was in the range of 1 ≦ D2 / D1 ≦ 50 were superior to Example 18 in low-temperature activation catalyst performance. Moreover, it has confirmed that it was not aggregated also by observation of the noble metal particle by TEM. As an example, the micrograph of Example 9 is as shown in FIG.
これに対して、比較例１〜５は、触媒粉末における第１の化合物にアルカリ金属若しくはアルカリ土類金属又はジルコニアを含んでいないこと、又は第２の化合物を具備していないことから、実施例１〜２５に比べると貴金属粒子の微粒子維持効果、低温活性化触媒性能が劣っていた。 On the other hand, Comparative Examples 1 to 5 do not contain alkali metal or alkaline earth metal or zirconia in the first compound in the catalyst powder, or do not include the second compound. Compared with 1-25, the fine particle maintenance effect of precious metal particles and the low temperature activation catalyst performance were inferior.
次に、以下に述べるように実施例２８、実施例２９及び比較例６の、実機サイズの排気ガス浄化用触媒を製造した。 Next, actual-size exhaust gas purifying catalysts of Examples 28, 29 and Comparative Example 6 were manufactured as described below.
〔実施例２８〕
実施例１９のPd触媒粉末、実施例２４のRh触媒粉末、ベーマイト及び10％濃度硝酸水溶液を混合投入し、磁性ポットに投入し、平均粒径を3[μｍ]まで粉砕した。得られたスラリを、コーディエライト製ハニカム基体（0.92L）に塗布し、余剰スラリを空気気流にて除去した後、130℃で乾燥、400℃で1時間、空気雰囲気下で焼成し、実施例２８の実機サイズ触媒ハニカムを得た。この時の触媒ハニカム1LあたりのPdおよびRh量は0.8ｇ/L、および0.4ｇ/Lであった。
Example 28
The Pd catalyst powder of Example 19, the Rh catalyst powder of Example 24, boehmite, and a 10% aqueous nitric acid solution were mixed and charged into a magnetic pot, and the average particle size was pulverized to 3 [μm]. The obtained slurry was applied to a cordierite honeycomb substrate (0.92L), the excess slurry was removed with an air stream, dried at 130 ° C, and fired at 400 ° C for 1 hour in an air atmosphere. The actual size catalyst honeycomb of Example 28 was obtained. The amounts of Pd and Rh per 1 L of the catalyst honeycomb at this time were 0.8 g / L and 0.4 g / L.
〔実施例２９〕
実施例２８のPd粉末の代わりに実施例２６で用いたPd粉末を用い、かつ、Rh粉末には実施例２７で用いたRh粉末を用いた以外は実施例２８と同様にして、実施例２９の実機サイズ触媒ハニカムを得た。
Example 29
Example 29 is the same as Example 28 except that the Pd powder used in Example 26 is used instead of the Pd powder of Example 28, and the Rh powder used in Example 27 is used as the Rh powder. The actual size catalyst honeycomb was obtained.
この時の触媒ハニカムの貴金属量は実施例２８と同様であった。 The amount of noble metal in the catalyst honeycomb at this time was the same as in Example 28.
〔比較例６〕
実施例２８のPd粉末の代わりに比較例3で用いたPd粉末を、およびRh粉末には比較例5で用いたRh粉末を用いた以外は同様にして、比較例6の実機サイズ触媒ハニカムを得た。
[Comparative Example 6]
In the same manner as in Example 28 except that the Pd powder used in Comparative Example 3 was used instead of the Pd powder in Example 28, and the Rh powder used in Comparative Example 5 was used as the Rh powder, the actual size catalyst honeycomb of Comparative Example 6 was used. Obtained.
この時の触媒ハニカムの貴金属量は実施例２８と同様であった。 The amount of noble metal in the catalyst honeycomb at this time was the same as in Example 28.
［車両評価試験］
上記実施例２８、実施例２９及び比較例６の実機サイズの各触媒ハニカム基体を、車両のエンジンの排気系に装着し、排気ガスのエミッション分析を行った。この車両評価試験における使用車両は日産自動車株式会社製であり、搭載されたエンジンは排気量２．５[Ｌ]のQE25ＤＥであった。ハニカム基体の容量は０．９２[Ｌ]であった。評価モードは、ＬＡ４−コールドスタートモードであった。
[Vehicle evaluation test]
Each of the actual honeycomb honeycomb substrates of Example 28, Example 29, and Comparative Example 6 was mounted on an exhaust system of a vehicle engine, and exhaust gas emission analysis was performed. The vehicle used in this vehicle evaluation test was manufactured by Nissan Motor Co., Ltd., and the installed engine was QE25DE with a displacement of 2.5 [L]. The capacity of the honeycomb substrate was 0.92 [L]. The evaluation mode was LA4-cold start mode.
［耐久試験前後のＯＳＣ量測定］
上記車両評価試験に用いた実施例２８、実施例２９及び比較例６の実機サイズの各触媒ハニカム基体について、耐久試験を行った。その耐久試験前後でのＯＳＣ量をそれぞれ測定し、初期の触媒の酸素貯蔵量を１．０としたときの耐久試験後の酸素貯蔵量の量比により、触媒のＯＳＣ耐久性を評価した。このＯＳＣ量の測定は、まず、耐久試験前後の触媒ハニカム基体の一部を取り出し、その触媒を、コーディエライト基体と共にすりつぶして、耐久試験前の粉末と耐久試験後の粉末とをそれぞれ用意した。各粉末については、一旦、空気気流中600[℃]で3時間、焼成し、触媒に付着した有機物除去を行った。その後、Ｈ ２ 気流中、600℃まで昇温し、触媒内の酸素脱離処理を行った。その後、500[℃]で安定化させた後、一定量の酸素をパルス導入し、熱伝導検出器(Thermal Conductivity Detector,TCD)にて、酸素吸着量の測定を行った。耐久試験前の粉末による初期の酸素吸着量Qｆと耐久試験前の粉末による耐久後酸素吸着量Qaの比をとり、耐久性の確認を行った。
[Measurement of OSC amount before and after endurance test]
Durability tests were performed on the actual catalyst honeycomb bases of Example 28, Example 29, and Comparative Example 6 used in the vehicle evaluation test. The amount of OSC before and after the endurance test was measured, and the OSC durability of the catalyst was evaluated based on the ratio of the amount of oxygen stored after the endurance test when the initial amount of oxygen stored in the catalyst was 1.0. For the measurement of the OSC amount, first, a part of the catalyst honeycomb substrate before and after the durability test was taken out, and the catalyst was ground together with the cordierite substrate to prepare a powder before the durability test and a powder after the durability test, respectively. . Each powder was once baked in an air stream at 600 [° C.] for 3 hours to remove organic substances attached to the catalyst. Thereafter, in H 2 stream, 600 ° C. or in heated and subjected to oxygen desorption process in the catalyst. Then, after stabilizing at 500 [° C.], a fixed amount of oxygen was pulsed, and the amount of adsorbed oxygen was measured with a thermal conductivity detector (TCD). The durability was confirmed by taking the ratio of the initial oxygen adsorption amount Qf by the powder before the durability test and the oxygen adsorption amount Qa after the durability by the powder before the durability test.
上述した車両評価試験及び耐久試験前後のＯＳＣ量測定の結果を表４に示す。
表４から分かるように、実施例２８及び２９は、実際の車両に取り付けた場合において、比較例６よりも排ガス残存率が少なく、優れた排気ガス浄化性能を有していることが確かめられた。また、耐久試験前後のＯＳＣ量測定の測定結果により、実施例２８及び２９は、比較例６よりもＯＳＣの低下が少なく、耐久性に優れていることが明らかとなった。特に、Ｙを含む実施例２９は、実施例２８と比べても実際の車両における排気ガス浄化性能、ＯＳＣ耐久性に優れていた。 As can be seen from Table 4, it was confirmed that Examples 28 and 29 had an exhaust gas remaining rate lower than that of Comparative Example 6 when mounted on an actual vehicle, and had excellent exhaust gas purification performance. . In addition, from the measurement results of the OSC amount measurement before and after the durability test, it was revealed that Examples 28 and 29 were less deteriorated in OSC and superior in durability than Comparative Example 6. In particular, Example 29 containing Y was superior in exhaust gas purification performance and OSC durability in an actual vehicle as compared with Example 28.
以上、本発明者らによってなされた発明を適用した実施の形態について説明したが、この実施の形態による本発明の開示の一部をなす論述及び図面により本発明は限定されることはない。すなわち、上記実施の形態に基づいて当業者等によりなされる他の実施の形態、実施例及び運用技術等は全て本発明の範疇に含まれることは勿論であることを付け加えておく。 As mentioned above, although the embodiment to which the invention made by the present inventors was applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.
１ 貴金属粒子（ＰＭ）
２ 第１の化合物（アンカー剤）
３ 第２の化合物
1 Precious metal particles (PM)
2 First compound (anchor agent)
3 Second compound
Claims (15)
前記貴金属粒子と接触し、当該貴金属粒子の移動を抑制する第１の化合物と、
前記貴金属粒子と前記第１の化合物を内包し、貴金属粒子の移動を抑制すると共に第１の化合物同士の接触に伴う第１の化合物の凝集を抑制する第２の化合物とからなり、
前記第１の化合物は、前記貴金属粒子を担持し、かつ、この貴金属粒子を担持した第１の化合物の単体又は集合体を、前記第２の化合物により隔てられた区画内に含み、かつ、
前記第１の化合物が、希土類元素と、アルカリ金属及びアルカリ土類金属のうちの少なくとも１種の金属とを含む複合物であることを特徴とする排気ガス浄化用触媒。 Precious metal particles,
A first compound that contacts the noble metal particles and inhibits movement of the noble metal particles;
Including the noble metal particles and the first compound, and comprising a second compound that suppresses the movement of the noble metal particles and suppresses the aggregation of the first compound accompanying the contact between the first compounds,
The first compound supports the noble metal particles, and includes a single substance or an aggregate of the first compounds supporting the noble metal particles in a compartment separated by the second compound, and
The exhaust gas purifying catalyst, wherein the first compound is a composite containing a rare earth element and at least one metal selected from alkali metals and alkaline earth metals.
第１の化合物を予め焼結させたのち、貴金属粒子をこの第１の化合物上に担持させる工程と、
前記貴金属粒子が担持された第１の化合物を粉砕する工程と、
前記粉砕された貴金属担持第１の化合物の周囲に、第２の化合物を形成する工程と
を含むことを特徴とする排気ガス浄化用触媒の製造方法。 A method for producing the exhaust gas purifying catalyst according to any one of claims 1 to 13 ,
A step of pre-sintering the first compound and then supporting the precious metal particles on the first compound;
Crushing the first compound on which the noble metal particles are supported;
And a step of forming a second compound around the pulverized noble metal-supported first compound. A method for producing an exhaust gas purifying catalyst.
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| JP2007237100A JP4971918B2 (en) | 2007-01-25 | 2007-09-12 | Exhaust gas purification catalyst and method for producing the same |
| EP20090001627 EP2055367A3 (en) | 2007-01-25 | 2008-01-23 | Exhaust gas purifying catalyst and manufacturing method thereof |
| EP08001250A EP1952876A1 (en) | 2007-01-25 | 2008-01-23 | Exhaust gas purifying catalyst and manufacturing method thereof |
| CN2008100045859A CN101301610B (en) | 2007-01-25 | 2008-01-25 | Exhaust gas purifying catalyst and manufacturing method thereof |
| KR1020080008004A KR100989224B1 (en) | 2007-01-25 | 2008-01-25 | Exhaust gas purifying catalyst and manufacturing method thereof |
| US12/010,514 US7851405B2 (en) | 2007-01-25 | 2008-01-25 | Exhaust gas purifying catalyst and manufacturing method thereof |
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| US20080277092A1 (en) | 2005-04-19 | 2008-11-13 | Layman Frederick P | Water cooling system and heat transfer system |
| US8575059B1 (en) | 2007-10-15 | 2013-11-05 | SDCmaterials, Inc. | Method and system for forming plug and play metal compound catalysts |
| JP5540521B2 (en) * | 2009-02-17 | 2014-07-02 | 日産自動車株式会社 | Exhaust gas purification catalyst and method for producing the same |
| JP6262413B2 (en) * | 2009-03-06 | 2018-01-17 | ユミコア日本触媒株式会社 | Exhaust gas purification catalyst, method for producing the same, and exhaust gas purification method |
| BRPI1011498A2 (en) * | 2009-11-17 | 2016-03-22 | Nissan Motor | exhaust gas purification catalyst and manufacturing method for the same |
| US9149797B2 (en) | 2009-12-15 | 2015-10-06 | SDCmaterials, Inc. | Catalyst production method and system |
| US9039916B1 (en) | 2009-12-15 | 2015-05-26 | SDCmaterials, Inc. | In situ oxide removal, dispersal and drying for copper copper-oxide |
| US8652992B2 (en) | 2009-12-15 | 2014-02-18 | SDCmaterials, Inc. | Pinning and affixing nano-active material |
| US8557727B2 (en) * | 2009-12-15 | 2013-10-15 | SDCmaterials, Inc. | Method of forming a catalyst with inhibited mobility of nano-active material |
| US9126191B2 (en) | 2009-12-15 | 2015-09-08 | SDCmaterials, Inc. | Advanced catalysts for automotive applications |
| JP2011147901A (en) * | 2010-01-22 | 2011-08-04 | Toyota Motor Corp | Exhaust gas purifying catalyst |
| US8669202B2 (en) | 2011-02-23 | 2014-03-11 | SDCmaterials, Inc. | Wet chemical and plasma methods of forming stable PtPd catalysts |
| MX2014001718A (en) | 2011-08-19 | 2014-03-26 | Sdcmaterials Inc | Coated substrates for use in catalysis and catalytic converters and methods of coating substrates with washcoat compositions. |
| JP5831083B2 (en) | 2011-09-20 | 2015-12-09 | 日産自動車株式会社 | Exhaust gas purification catalyst and method for producing the same |
| US9156025B2 (en) | 2012-11-21 | 2015-10-13 | SDCmaterials, Inc. | Three-way catalytic converter using nanoparticles |
| US9511352B2 (en) | 2012-11-21 | 2016-12-06 | SDCmaterials, Inc. | Three-way catalytic converter using nanoparticles |
| JP6106197B2 (en) * | 2013-02-08 | 2017-03-29 | ユミコア日本触媒株式会社 | NOx storage reduction type exhaust gas purification catalyst and exhaust gas purification method using the catalyst |
| EP2988863A2 (en) | 2013-07-11 | 2016-03-02 | SABIC Global Technologies B.V. | Use of lanthanide oxides to reduce sintering of catalysts |
| CN105592921A (en) | 2013-07-25 | 2016-05-18 | Sdc材料公司 | Washcoats and coated substrates for catalytic converters and method for manufacturing and using same |
| KR20160074574A (en) | 2013-10-22 | 2016-06-28 | 에스디씨머티리얼스, 인코포레이티드 | COMPOSITIONS OF LEAN NOx TRAP |
| MX2016004991A (en) | 2013-10-22 | 2016-08-01 | Sdcmaterials Inc | Catalyst design for heavy-duty diesel combustion engines. |
| US9415378B2 (en) * | 2013-12-02 | 2016-08-16 | Saudi Basic Industries Corporation | Dehydrogenation catalyst, its use and method of preparation |
| WO2015143225A1 (en) | 2014-03-21 | 2015-09-24 | SDCmaterials, Inc. | Compositions for passive nox adsorption (pna) systems |
| JP6701518B2 (en) * | 2015-04-14 | 2020-05-27 | 日産自動車株式会社 | Exhaust gas purifying catalyst, method of manufacturing exhaust gas purifying catalyst, and exhaust gas purifying monolith catalyst |
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| JPH08131830A (en) * | 1994-11-07 | 1996-05-28 | Toyota Motor Corp | Catalyst for purification of exhaust gas |
| JP4779271B2 (en) * | 2001-09-19 | 2011-09-28 | トヨタ自動車株式会社 | catalyst |
| JP3861647B2 (en) * | 2001-10-09 | 2006-12-20 | トヨタ自動車株式会社 | Exhaust gas purification catalyst |
| JP4218364B2 (en) * | 2002-03-29 | 2009-02-04 | 株式会社豊田中央研究所 | Method for producing metal oxide |
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| JP4959129B2 (en) * | 2004-02-16 | 2012-06-20 | 株式会社キャタラー | Exhaust gas purification catalyst |
| JP4764609B2 (en) * | 2004-03-15 | 2011-09-07 | 独立行政法人産業技術総合研究所 | Nitrogen oxide removal catalyst |
| JP4589032B2 (en) * | 2004-05-28 | 2010-12-01 | 戸田工業株式会社 | Exhaust gas purification catalyst and oxygen storage material for the catalyst |
| JP2006326554A (en) * | 2005-05-30 | 2006-12-07 | Nissan Motor Co Ltd | Catalyst for purifying exhaust gas, and method for producing it |
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