JP5130632B2 - 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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- 239000003054 catalyst Substances 0.000 title claims description 89
- 238000000746 purification Methods 0.000 title claims description 23
- 238000004519 manufacturing process Methods 0.000 title claims description 22
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 120
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 108
- 239000002245 particle Substances 0.000 claims description 102
- 229910000510 noble metal Inorganic materials 0.000 claims description 70
- 239000000463 material Substances 0.000 claims description 66
- 239000002923 metal particle Substances 0.000 claims description 56
- 239000000084 colloidal system Substances 0.000 claims description 51
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- 239000002243 precursor Substances 0.000 claims description 29
- 238000001179 sorption measurement Methods 0.000 claims description 29
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- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical group O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 22
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- 239000007789 gas Substances 0.000 description 50
- 230000000052 comparative effect Effects 0.000 description 40
- 239000010948 rhodium Substances 0.000 description 37
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 36
- 229910001928 zirconium oxide Inorganic materials 0.000 description 36
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 32
- 229910017604 nitric acid Inorganic materials 0.000 description 32
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 30
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- 239000007864 aqueous solution Substances 0.000 description 27
- 229910000420 cerium oxide Inorganic materials 0.000 description 27
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 27
- 239000002131 composite material Substances 0.000 description 24
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 24
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 23
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- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 22
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 22
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 14
- 239000000758 substrate Substances 0.000 description 14
- 238000002360 preparation method Methods 0.000 description 13
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- 150000001875 compounds Chemical class 0.000 description 12
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 12
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- 238000004220 aggregation Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 4
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 239000000839 emulsion Substances 0.000 description 4
- 239000011572 manganese Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 238000005054 agglomeration Methods 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
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- 229920002125 Sokalan® Polymers 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
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- VGBWDOLBWVJTRZ-UHFFFAOYSA-K cerium(3+);triacetate Chemical compound [Ce+3].CC([O-])=O.CC([O-])=O.CC([O-])=O VGBWDOLBWVJTRZ-UHFFFAOYSA-K 0.000 description 2
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- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 1
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- 229940071125 manganese acetate Drugs 0.000 description 1
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
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Description
本発明は、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 purification catalyst and a method for producing the same.
近年、自動車用の排出ガス規制は益々厳しくなる一方であり、排気ガス浄化用触媒には、排ガス中に含まれる有害な成分、例えば、未燃焼炭化水素（ＨＣ）や一酸化炭素（ＣＯ）の浄化をより高効率で行なうことが要求されている。排ガス浄化触媒は、アルミナ等の基材の表面に貴金属粒子３を担持したものであり、排ガス中に含まれる有害な成分、例えば未燃焼炭化水素（ＨＣ）や一酸化炭素（ＣＯ）を貴金属粒子で酸化し、無害な成分である水やガスに変換する。そして、一般に、触媒の浄化性能は貴金属粒子の表面積が大きいほど向上するため、貴金属粒子の粒径を小さくすることにより、貴金属粒子の表面積を大きくして表面エネルギーを増大させることが行われている。 In recent years, exhaust gas regulations for automobiles are becoming more and more stringent, and exhaust gas purification catalysts include harmful components contained in exhaust gas, such as unburned hydrocarbons (HC) and carbon monoxide (CO). There is a demand for more efficient purification. The exhaust gas purification catalyst is a catalyst in which noble metal particles 3 are supported on the surface of a substrate such as alumina, and harmful components contained in the exhaust gas, such as unburned hydrocarbon (HC) and carbon monoxide (CO), are precious metal particles. Oxidizes with water and gas, which is harmless. And generally, since the purification performance of the catalyst is improved as the surface area of the noble metal particles is increased, the surface energy is increased by increasing the surface area of the noble metal particles by reducing the particle size of the noble metal particles. .
ここで、排気ガス浄化用触媒の貴金属粒子は、初期段階では数ｎｍ以下の超微粒子状態になっている。しかし、高温の酸化雰囲気中に排気ガス浄化用触媒が晒されているうちに、貴金属粒子の表面が酸化され、近傍の貴金属粒子同士が合体して数十ｎｍに粗大化してしまい、貴金属粒子の表面積が低下して有害物質の浄化率が低下するという問題がある。 Here, the noble metal particles of the exhaust gas purifying catalyst are in an ultrafine particle state of several nm or less in the initial stage. However, while the exhaust gas purification catalyst is exposed to a high-temperature oxidizing atmosphere, the surface of the noble metal particles is oxidized, and the noble metal particles in the vicinity coalesce and become coarse to several tens of nanometers. There is a problem in that the surface area decreases and the purification rate of harmful substances decreases.
この貴金属粒子の粗大化による表面積低下を防止すべく、逆ミセル法などのような表面積の大きい貴金属粒子の製法に関する開発が進んでいる。この逆ミセル法とは、まず、有機溶媒中に界面活性剤と触媒活性な成分（例えば、貴金属元素）を含む水溶液とを混合する。その後、有機溶媒中に、貴金属を含む水溶液を含有する逆ミセルが形成されたエマルジョン溶液を調製し、貴金属を沈殿させた後、還元又は不溶化し、逆ミセルの中で微粒化した貴金属を析出させる方法である。 In order to prevent a decrease in the surface area due to the coarsening of the noble metal particles, development relating to a method for producing noble metal particles having a large surface area such as a reverse micelle method has been advanced. In the reverse micelle method, first, an aqueous solution containing a surfactant and a catalytically active component (for example, a noble metal element) is mixed in an organic solvent. After that, an emulsion solution in which reverse micelles containing an aqueous solution containing a noble metal are formed in an organic solvent is prepared. Is the method.
また、特開２０００−４２４１１号公報には、エマルジョン溶液調製工程において、逆ミセルの中に酸素吸蔵作用を有する元素を含有させて触媒を製造する方法が開示されている。この逆ミセル法では、エマルジョン溶液中に含まれる逆ミセルの中で、基材に触媒活性な成分を担持した後、逆ミセルを崩壊させて、得られた沈殿物を濾過、乾燥、粉砕、焼成する各工程を経て触媒としている。本製造方法を用いて製造された触媒は、基材に酸素吸蔵作用を有する元素を担持できるだけではなく、基材の最表面及び基材中に形成された孔部表面にも触媒活性な成分を担持するため、触媒の活性を高めることができる。 Japanese Patent Application Laid-Open No. 2000-42411 discloses a method for producing a catalyst by containing an element having an oxygen storage effect in reverse micelles in an emulsion solution preparation step. In this reverse micelle method, after supporting the catalytically active component on the base material in the reverse micelle contained in the emulsion solution, the reverse micelle is disintegrated, and the resulting precipitate is filtered, dried, pulverized, and calcined. Each step is used as a catalyst. The catalyst produced using this production method not only supports an element having an oxygen storage effect on the base material, but also has a catalytically active component on the outermost surface of the base material and the surface of the pores formed in the base material. Since it is supported, the activity of the catalyst can be increased.
しかしながら、前述した逆ミセル法では、逆ミセルが形成されたエマルジョン溶液を噴霧焼成して触媒を製造するため、製造工程が複雑化して製造コストが上昇するという問題があった。 However, in the reverse micelle method described above, a catalyst is manufactured by spray firing the emulsion solution in which the reverse micelle is formed, so that the manufacturing process becomes complicated and the manufacturing cost increases.
そこで、本発明は、製造工程が簡易で、高い浄化率を長期間保持することができる排気ガス浄化用触媒及びその製造方法を提供することを目的とする。 Accordingly, an object of the present invention is to provide an exhaust gas purifying catalyst that has a simple manufacturing process and can maintain a high purification rate for a long period of time, and a method for manufacturing the same.
前記目的を達成するために、本発明に係る排気ガス浄化用触媒は、貴金属粒子と、繊維状に形成された複数の粒子からなり、前記貴金属粒子の周囲を取り囲む内包材と、該内包材によって周囲が取り囲まれた前記貴金属粒子を担持する基材とを含んでなり、前記内包材によって形成される間隙の大きさは、前記貴金属粒子の径よりも小さく設定されると共に、下記算出式で算出される露出率が８５％以上１００％未満である排気ガス浄化用触媒である。
露出率＝（貴金属粒子の周囲を内包材で覆った触媒にガス吸着法によりＣＯガスを接触させたときのＣＯ吸着量）÷（ＴＥＭ観察によって測定された貴金属粒子の表面積に基づいて算出されたＣＯ吸着量）×１００
In order to achieve the above object, an exhaust gas purifying catalyst according to the present invention comprises noble metal particles, a plurality of particles formed in a fiber shape, an inner packaging material surrounding the noble metal particles, and the inner packaging material. And a base material supporting the noble metal particles surrounded by the surroundings, and the size of the gap formed by the inner packaging material is set smaller than the diameter of the noble metal particles and is calculated by the following calculation formula: The exhaust gas purifying catalyst has an exposure rate of 85% or more and less than 100% .
Exposure rate = (CO adsorption amount when CO gas is brought into contact with a catalyst in which the periphery of the noble metal particles is covered with an inclusion material by the gas adsorption method) ÷ (calculated based on the surface area of the noble metal particles measured by TEM observation) CO adsorption amount) x 100
また、本発明に係る排気ガス浄化用触媒の製造方法は、アルミナ前駆体を水に分散し、解膠する工程と、このアルミナ前駆体の分散液中に、貴金属コロイドを分散させたのち、乾燥し、焼成する工程とを含むことを特徴とする。 Further, the method for producing an exhaust gas purifying catalyst according to the present invention includes a step of dispersing an alumina precursor in water and peptizing, and after dispersing a noble metal colloid in the dispersion of the alumina precursor, drying. And a step of firing.
本発明に係る排気ガス浄化用触媒によれば、貴金属粒子の周囲を、繊維状に形成された複数の粒子からなる内包材によって取り囲んでいるため、基材上における貴金属粒子の移動による凝集化を抑制することができ、貴金属の表面積を大きい状態に保持することができる。 According to the exhaust gas purifying catalyst according to the present invention, surroundings, since the surrounding depending on inner wrapper consisting of a plurality of particles formed into fibers, agglomeration due to the movement of the noble metal particles on the base material of the noble metal particles And the surface area of the noble metal can be kept large.
また、本発明に係る排気ガス浄化用触媒の製造方法によれば、貴金属粒子の周囲を、繊維状に形成された複数の粒子からなる内包材によって取り囲んだ触媒を効率的に製造することができる。従って、長期間使用した後においても、貴金属粒子同士が凝集せずに大きい表面積を保持することができるため、高い浄化性能を保つことができる。 Further, according to the method of manufacturing the exhaust gas purifying catalyst according to the present invention, the periphery of the noble metal particles, is possible to manufacture the inner material to thus encircled catalyst comprising a plurality of particles formed in fibrous efficiently it can. Therefore, even after a long period of use, since a large surface area can be maintained without agglomeration of noble metal particles, high purification performance can be maintained.
以下、本発明の実施形態を図面に基づき説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
図１は、本発明に係る排気ガス浄化用触媒の表面の状態を拡大して示す概略図である。 FIG. 1 is an enlarged schematic view showing the state of the surface of an exhaust gas purifying catalyst according to the present invention.
図１に示すように、本発明に係る排気ガス浄化用触媒１は、排気ガスに接触して有害成分を浄化させる活性金属である貴金属粒子３と、該貴金属粒子３の外周をケージ状に覆う繊維状の内包材５と、該内包材５によって内包された貴金属粒子３を担持する基材（図示せず）とを備えている。 As shown in FIG. 1, an exhaust gas purifying catalyst 1 according to the present invention covers noble metal particles 3 that are active metals that come into contact with exhaust gas to purify harmful components, and covers the outer periphery of the noble metal particles 3 in a cage shape. A fibrous inner packaging material 5 and a base material (not shown) carrying the noble metal particles 3 encapsulated by the inner packaging material 5 are provided.
このように、本発明に係る排気ガス浄化用触媒１においては、貴金属粒子３の周囲を繊維状の複数の内包材５によってケージ状に取り囲んでいるため、基材上における貴金属粒子３の移動による凝集化を抑制することができ、貴金属粒子３の表面積を大きい状態に保持することができる。 As described above, in the exhaust gas purifying catalyst 1 according to the present invention, the noble metal particles 3 are surrounded by the plurality of fibrous inclusions 5 in a cage shape, so that the noble metal particles 3 move on the base material. Aggregation can be suppressed, and the surface area of the noble metal particles 3 can be kept large.
貴金属粒子３の生成に用いる貴金属粒子用原料は、白金（Ｐｔ）、パラジウム（Ｐｄ）、ロジウム（Ｒｈ）の群から選択される一又は二以上の金属が好ましい。また、排気ガス浄化用触媒を製造する際には、図２（ｂ）に示すように、貴金属粒子３をコロイドにした貴金属コロイドの状態で用いることが好ましい。 The raw material for noble metal particles used for producing the noble metal particles 3 is preferably one or more metals selected from the group of platinum (Pt), palladium (Pd), and rhodium (Rh). Further, when producing the exhaust gas purifying catalyst, it is preferable to use it in the state of a noble metal colloid in which the noble metal particles 3 are colloidal as shown in FIG. 2 (b).
なお、図２（ｂ）は、Ｐｔコロイド７を拡大して示す概略図であり、貴金属粒子３であるＰｔ粒子の周囲を保護コロイド９としての高分子保護層によって覆っている。この保護コロイド９としては、例えば、ポリビニールピロリドン（ＰＶＰ）、ポリエチレンイミン、ポリアクリル酸などが好ましい。 FIG. 2B is an enlarged schematic view showing the Pt colloid 7, and the periphery of the Pt particles as the noble metal particles 3 is covered with a polymer protective layer as the protective colloid 9. As this protective colloid 9, for example, polyvinylpyrrolidone (PVP), polyethyleneimine, polyacrylic acid and the like are preferable.
前記内包材５は、図２（ａ）に示すように、アルミナからなる繊維状に形成された粒子が複数集まった粒子群から形成されることが好ましい。各粒子の寸法は、長さが１０ｎｍ〜２００ｎｍ、幅が５ｎｍ〜２０ｎｍが好ましい。 As shown in FIG. 2 (a), the inner packaging material 5 is preferably formed from a particle group in which a plurality of particles made of alumina are collected. The size of each particle is preferably 10 nm to 200 nm in length and 5 nm to 20 nm in width.
内包材５の生成に用いる内包材用原料は、アルミナ前駆体であるベーマイトが好ましく、また、セリウム化合物や遷移金属化合物を含んだベーマイトも用いることができる。 The raw material for the inner packaging material used for the production of the inner packaging material 5 is preferably boehmite which is an alumina precursor, and boehmite containing a cerium compound or a transition metal compound can also be used.
基材は、アルミナ（Ａｌ２Ｏ３）、セリア（ＣｅＯ２）、ジルコニア（ＺｒＯ２）、マグネシア（ＭｇＯ）、シリカ（ＳｉＯ２）、ＴｉＯ２、シリカアルミナ、酸化バナジウム及び酸化タングステンの群から選択される一又は二以上の元素からなる多孔質酸化物を好適に用いることができる。 The substrate is selected from the group consisting of alumina (Al 2 O 3 ), ceria (CeO 2 ), zirconia (ZrO 2 ), magnesia (MgO), silica (SiO 2 ), TiO 2 , silica alumina, vanadium oxide and tungsten oxide. A porous oxide composed of one or two or more elements can be suitably used.
次に、露出率の求め方について説明する。 Next, how to determine the exposure rate will be described.
まず、ＴＥＭの観察により貴金属粒子３の平均粒子径を求め、この平均粒子径から貴金属粒子３の平均表面積を算出する。この平均表面積に対応するＣＯ吸着量を計算にて求め基準値（Ａ）とする。つまり、基準値（Ａ）は、貴金属粒子３の周囲が内包材５で全く覆われていない状態のＣＯ吸着量を計算にて算出した値である。 First, the average particle diameter of the noble metal particles 3 is obtained by TEM observation, and the average surface area of the noble metal particles 3 is calculated from the average particle diameter. The amount of CO adsorption corresponding to this average surface area is obtained by calculation and used as the reference value (A). That is, the reference value (A) is a value obtained by calculating the CO adsorption amount in a state where the periphery of the noble metal particle 3 is not covered with the inner packaging material 5 at all.
一方、貴金属粒子３を内包材５でケージ状に覆った本発明の触媒にガス吸着法によりＣＯガスを当て、そのときのＣＯ吸着量をＢとする。この場合、貴金属粒子３の露出率は、（Ｂ／Ａ）×１００ [％]と算出する。 On the other hand, CO gas is applied by the gas adsorption method to the catalyst of the present invention in which the noble metal particles 3 are covered with the inner packaging material 5 in a cage shape, and the CO adsorption amount at that time is B. In this case, the exposure rate of the noble metal particles 3 is calculated as (B / A) × 100 [%].
そして、露出率は、８５％以上かつ１００％未満が好ましい。この露出率は、排気ガス中の有害成分を浄化する性能に影響を及ぼす。即ち、露出率が８５％未満の場合は、排気ガス中の有害成分が貴金属粒子３に接触する確率が低くなるため、浄化効率が低下する。また、露出率が１００％になると、貴金属粒子３を覆う内包材５がないため、貴金属粒子３の凝集を抑制することが困難となる。 The exposure rate is preferably 85% or more and less than 100%. This exposure rate affects the performance of purifying harmful components in the exhaust gas. That is, when the exposure rate is less than 85%, the purification efficiency is lowered because the probability that harmful components in the exhaust gas come into contact with the noble metal particles 3 decreases. When the exposure rate is 100%, it is difficult to suppress aggregation of the noble metal particles 3 because there is no inner packaging material 5 that covers the noble metal particles 3.
次に、排気ガス浄化用触媒を製造する方法を説明する。 Next, a method for producing an exhaust gas purification catalyst will be described.
（１）まず、アルミナ前駆体を水に分散し、解膠する。 (1) First, an alumina precursor is dispersed in water and peptized.
例えば、図２（ａ）に示すように、アルミナ前駆体として前述の繊維状のベーマイトを用い、該ベーマイトを水に分散させると共に、この分散液に硝酸や酢酸等を加えて解膠する。なお、前記アルミナ前駆体以外にも、セリア含有アルミナ前駆体及び遷移金属含有アルミナ前駆体なども採用することができる。 For example, as shown in FIG. 2A, the above-described fibrous boehmite is used as an alumina precursor, the boehmite is dispersed in water, and nitric acid, acetic acid, or the like is added to the dispersion to peptize. In addition to the alumina precursor, a ceria-containing alumina precursor and a transition metal-containing alumina precursor can also be employed.
（２）次いで、アルミナ前駆体の分散液中に、貴金属コロイドを分散させる。 (2) Next, the noble metal colloid is dispersed in the alumina precursor dispersion.
図２（ｂ）に示すように、貴金属コロイドであるＰｔコロイド７は、Ｐｔ粒子の周囲に保護コロイド９として高分子保護層を配置している。この保護コロイド９としては、例えば、ポリビニールピロリドン（ＰＶＰ）、ポリエチレンイミン、ポリアクリル酸などが好ましい。 As shown in FIG. 2B, the Pt colloid 7 which is a noble metal colloid has a polymer protective layer disposed as a protective colloid 9 around the Pt particles. As this protective colloid 9, for example, polyvinylpyrrolidone (PVP), polyethyleneimine, polyacrylic acid and the like are preferable.
そして、アルミナ前駆体の分散液中に、貴金属コロイドを分散させると、図３に示すように、保護コロイド９を配置した貴金属粒子３の周囲に、アルミナ前駆体１１が配置される。 When the precious metal colloid is dispersed in the alumina precursor dispersion, the alumina precursor 11 is disposed around the precious metal particles 3 on which the protective colloid 9 is disposed, as shown in FIG.
（３）そして、アルミナ前駆体１１と貴金属コロイドが分散した分散液を乾燥し、焼成する。 (3) The dispersion in which the alumina precursor 11 and the noble metal colloid are dispersed is dried and fired.
前記アルミナ前駆体１１の分散液中に貴金属コロイドを分散させてスラリーとし、スプレードライヤ等を用いて乾燥させたのち、所定温度（例えば、４００℃）にて焼成することにより、貴金属を担持した粉末が得られる。 A powder carrying a noble metal by dispersing a noble metal colloid in a dispersion of the alumina precursor 11 to form a slurry, drying using a spray dryer, etc., and firing at a predetermined temperature (for example, 400 ° C.). Is obtained.
この粉末は、図１に示すように、繊維状に形成された内包材５によって、貴金属粒子３であるＰｔ粒子の周囲が覆われている。前記内包材５は、アルミナからなる繊維状に形成された複数の粒子によって構成されている。前記乾燥は、スプレードライヤに限らず、減圧乾燥及び真空凍結乾燥も適用することができる。 As shown in FIG. 1, the surrounding of the Pt particles, which are the noble metal particles 3, is covered with the inner packaging material 5 formed in a fiber shape. The inner packaging material 5 is composed of a plurality of particles formed in a fiber shape made of alumina. The drying is not limited to a spray dryer, and vacuum drying and vacuum freeze drying can also be applied.
最後に、前記粉末を用いてスラリー化し、ハニカム担体に塗布したのち、乾燥及び焼成することにより、本発明に係る排気ガス浄化用触媒を製造することができる。 Finally, the catalyst for exhaust gas purification according to the present invention can be manufactured by making a slurry using the powder, applying the slurry to the honeycomb carrier, and drying and firing.
前記排気ガス浄化用触媒の製造方法によれば、貴金属粒子３の周囲を内包材５によってケージ状に取り囲んだ触媒１を効率的に製造することができる。従って、長期間使用した後においても、貴金属粒子３同士が凝集せずに大きい表面積を保持することができるため、高い浄化性能を保つことができる。 According to the method for producing the exhaust gas purifying catalyst, the catalyst 1 in which the periphery of the noble metal particles 3 is surrounded by the inner packaging material 5 in a cage shape can be efficiently produced. Therefore, even after a long period of use, since a large surface area can be maintained without agglomeration of the noble metal particles 3, high purification performance can be maintained.
また、前記アルミナ前駆体１１は、繊維状に形成されているため、貴金属粒子３の周囲を確実にケージ状に覆うことができる。 Moreover, since the alumina precursor 11 is formed in a fiber shape, the periphery of the noble metal particles 3 can be reliably covered in a cage shape.
さらに、前記アルミナ前駆体１１としてベーマイトを用いるため、貴金属粒子３の凝集を抑制する効果が非常に高くなる。 Furthermore, since boehmite is used as the alumina precursor 11, the effect of suppressing aggregation of the noble metal particles 3 is very high.
そして、前記解膠は、酸により行なわれ、アルミナ前駆体１１を分散させた分散液中のｐＨは酸性領域である７未満である。ｐＨ値が７以上になると、アルミナ前駆体１１を解膠させることが困難となり、貴金属粒子３の周囲をアルミナ前駆体１１で覆う構造を形成しにくくなるため好ましくない。 The peptization is performed with an acid, and the pH of the dispersion in which the alumina precursor 11 is dispersed is less than 7 in the acidic region. A pH value of 7 or more is not preferable because it becomes difficult to pept the alumina precursor 11 and it becomes difficult to form a structure in which the periphery of the noble metal particles 3 is covered with the alumina precursor 11.
また、前記貴金属コロイドは、Ｐｔ、Ｐｄ、Ｒｈより選択される貴金属粒子３の周囲に、保護コロイド９として高分子保護層を配置しているため、貴金属粒子３の周囲にアルミナ前駆体１１を効率的に配置することができる。 The noble metal colloid has a protective polymer colloid 9 around the noble metal particles 3 selected from Pt, Pd, and Rh, so that the alumina precursor 11 is efficiently used around the noble metal particles 3. Can be arranged.
そして、乾燥として、スプレードライヤを用いた乾燥、減圧乾燥、及び真空凍結乾燥のうちのいずれかを用いるため、貴金属粒子３の周囲に内包材５を固定的に配置することができる。しかし、前記乾燥方法以外の蒸発乾固法等では、貴金属粒子３と内包材５との構造が乾燥中に変化してしまい、貴金属粒子３の周囲に内包材５を配置する構造となりにくため、好ましくない。 Since any one of drying using a spray dryer, drying under reduced pressure, and vacuum freeze drying is used as drying, the inner packaging material 5 can be fixedly disposed around the noble metal particles 3. However, in the evaporative drying method other than the drying method, the structure of the noble metal particles 3 and the inner packaging material 5 changes during drying, and the inner packaging material 5 is unlikely to be arranged around the noble metal particles 3. It is not preferable.
次いで、実施例によって本発明の実施形態を更に具体的に説明する。なお、各実施例及び比較例における詳細な内容を表１にまとめて示す。
［実施例１］
１０×５ｎｍのベーマイトを用いた触媒の調製
アルミナ前駆体であるベーマイト（１０×５ｎｍ、含水率２４％）２６２．０６ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ３に調整した。これに、Ｐｔを０．８４ｇ含むＰｔコロイドを加え分散させてスラリーを作成した。このＰｔコロイドは、Ｐｔ粒子径が２．６ｎｍであり、保護コロイドがポリビニールピロリドン（ＰＶＰ）であった。
[Example 1]
Preparation of catalyst using 10 × 5 nm boehmite Boehmite (10 × 5 nm, water content 24%) 262.06 g, which is an alumina precursor, was dispersed in 2000 ml of water and adjusted to pH 3 by adding nitric acid. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed to prepare a slurry. This Pt colloid had a Pt particle size of 2.6 nm, and the protective colloid was polyvinylpyrrolidone (PVP).
前記スラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ａ）
この粉末Ａについて、ガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求めた。また、ＴＥＭ（透過型電子顕微鏡）による観察によりＰｔ粒子径の平均値を求め、この平均粒子径からＰｔ粒子の平均表面積を算出した。そして、この平均表面積よりＣＯ吸着量を計算にて基準値を求めた。前記単位重量あたりのＣＯ吸着量を基準値で除した値を露出率とすると、露出率は、８７％であった。
The slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder A)
For this powder A, the amount of CO adsorbed per unit weight (that is, 1 g) was determined by a gas adsorption method. Moreover, the average value of Pt particle diameter was calculated | required by observation with TEM (transmission electron microscope), and the average surface area of Pt particle | grains was computed from this average particle diameter. And the standard value was calculated | required by calculating CO adsorption amount from this average surface area. When the value obtained by dividing the CO adsorption amount per unit weight by the reference value was defined as the exposure rate, the exposure rate was 87%.
粉末Ａを１７３．４ｇ、アルミナゾルを１．６ｇ、更に水を３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーａ）
次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化し、ジルコニア基材を調製した。ロジウムを０．６％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９％、酸化ジルコニウム６％、酸化ランタン６％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーａを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例１の試料とした。
173.4 g of powder A, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added to grind the base material to obtain a slurry having an average particle diameter of 3 μm. (Slurry a)
Next, rhodium nitrate was impregnated with a composite compound of γ-alumina and zirconium oxide containing 3 wt% as zirconium to prepare 0.6 wt% rhodium supported powder. Further, zirconium oxide was compounded with 24% of cerium oxide to prepare a zirconia base material. 116.55 g of powder carrying 0.6% rhodium, 44.45 g of zirconia base material, 11 g of alumina base material (composite of 9% cerium oxide, 6% zirconium oxide and 6% lanthanum oxide on γ-alumina) 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) with a diameter of 36 mmφ and a 400 cell 6 mil was coated with 141 g / L of slurry a and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. The sample of Example 1 was obtained.
得られた実施例１の触媒は、Ｐｔ：０．５８７ｇ／Ｌ， Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 1 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[実施例２]
６０×１０ｎｍのベーマイトを用いた触媒の調製
ベーマイト（６０×１０ｎｍ、含水率２４％）２６２．０６ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ３に調整した。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Example 2]
Preparation of catalyst using boehmite of 60 × 10 nm Boehmite (60 × 10 nm, moisture content 24%) 262.06 g was dispersed in 2000 ml of water, and nitric acid was added to adjust the pH to 3. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｂ）
この粉末Ｂについて、ガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察によりＰｔ粒子径の平均値を求め、前記実施例１と同様にして露出率を求めると、９５％であった。
This slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder B)
For this powder B, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by the gas adsorption method, and the average value of the Pt particle diameter was determined by observation with a TEM (transmission electron microscope). Similarly, the exposure rate was 95%.
粉末Ｂを１７３．４ｇ、アルミナゾルを１．６ｇ、更に水を３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｂ）
次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化し、ジルコニア基材を調製した。ロジウム０．６％担持粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９％、酸化ジルコニウム６％、酸化ランタン６％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径が３μｍのスラリーとした。（スラリーＲ）
直径が３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｂを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例１の試料とした。
173.4 g of powder B, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added to grind the base material to obtain a slurry having an average particle diameter of 3 μm. (Slurry b)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% as zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% rhodium. Further, zirconium oxide was compounded with 24% of cerium oxide to prepare a zirconia base material. Rhodium 0.6% supported powder 116.55g, zirconia base material 44.45g, alumina base material (composite of γ-alumina with cerium oxide 9%, zirconium oxide 6%, lanthanum oxide 6%), alumina sol 3g Was added to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle size of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and 400 cells 6 mil was coated with 141 g / L of slurry b and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. Thus, a sample of Example 1 was obtained.
得られた実施例２の触媒は、Ｐｔ：０．５８７ｇ／Ｌ， Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 2 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[実施例３]
１２０×１０ｎｍのベーマイトを用いた触媒の調製
ベーマイト（１２０×１０ｎｍ、含水率２５％）２６５．５５ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ３に調整した。これにＰｔとして０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Example 3]
Preparation of catalyst using 120 × 10 nm boehmite 265.55 g of boehmite (120 × 10 nm, water content 25%) was dispersed in 2000 ml of water and adjusted to pH 3 by adding nitric acid. Pt colloid containing 0.84 g of Pt was added to this and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｃ）
この粉末Ｃについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により前記実施例１，２と同様に露出率を求めると、９２％であった。
This slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder C)
For this powder C, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by the gas adsorption method, and the exposure rate was determined in the same manner as in Examples 1 and 2 by observation with a TEM (transmission electron microscope). 92%.
粉末Ｃを１７３．４ｇ、アルミナゾルを１．６ｇ、更に水を３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｃ）
次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇと、ジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％の硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径が３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｃを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例３の試料とした。
173.4 g of powder C, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added to grind the base material to obtain a slurry having an average particle diameter of 3 μm. (Slurry c)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% as zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55g of powder carrying 0.6wt% rhodium, 44.45g of zirconia base material, 11g of alumina base material (composite of γ-alumina with cerium oxide 9wt%, zirconium oxide 6wt%, lanthanum oxide 6wt%) Then, 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and a 400 cell 6 mil was coated with 141 g / L of slurry c and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. The sample of Example 3 was obtained.
得られた実施例３の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 3 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[実施例４]
１６０×１５ｎｍのベーマイトを用いた触媒の調製
ベーマイト（１６０×１５ｎｍ、含水率２６％）２６９．１４ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ３に調整した。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Example 4]
Preparation of catalyst using 160 × 15 nm boehmite 269.14 g of boehmite (160 × 15 nm, water content 26%) was dispersed in 2000 ml of water and adjusted to pH 3 by adding nitric acid. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｄ）
この粉末Ｄについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により平均Ｐｔ粒子径を求め、前記実施例１〜３で算出したように露出率を求めると、９８％であった。
This slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder D)
For this powder D, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by gas adsorption, and the average Pt particle size was determined by observation with a TEM (transmission electron microscope). As described above, the exposure rate was 98%.
粉末Ｄを１７３．４ｇ、アルミナゾルを１．６ｇ、更に水を３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径３μｍのスラリーとした。（スラリーｄ）
次に、ジルコニウムを３ｗｔ％含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９％、酸化ジルコニウム６％、酸化ランタン６％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｄを１４１ｇ／Ｌ コーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例４の試料とした。
173.4 g of powder D, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added to grind the base material to obtain a slurry having an average particle diameter of 3 μm. (Slurry d)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% of zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% of rhodium. Further, zirconium oxide was compounded with 24% of cerium oxide to prepare a zirconia base material. 116 g of rhodium-supported powder 116.55 g, 44.45 g of zirconia base material, 11 g of alumina base material (composite of γ-alumina 9% cerium oxide, 6% zirconium oxide, 6% lanthanum oxide), 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) with a diameter of 36 mmφ and a 400 cell 6 mil was coated with 141 g / L of slurry d and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. The sample of Example 4 was obtained.
得られた実施例４の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 4 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[実施例５]
２００×２０ｎｍのベーマイトを用いた触媒の調製
ベーマイト（２００×２０ｎｍ、含水率２６％）２６９．１４ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ３に調整した。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Example 5]
Preparation of catalyst using boehmite of 200 × 20 nm Boehmite (200 × 20 nm, water content 26%) 269.14 g was dispersed in 2000 ml of water and adjusted to pH 3 by adding nitric acid. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｅ）
この粉末Ｅについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により、実施例１〜４と同様に露出率を求めると、９７％であった。
This slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder E)
For this powder E, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by gas adsorption method, and the exposure rate was determined in the same manner as in Examples 1 to 4 by observation with TEM (transmission electron microscope). 97%.
粉末Ｅを１７３．４ｇとアルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｅ）
次に、ジルコニウムを３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウムｗｔ６％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｅを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例５の試料とした。
173.4 g of powder E, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of a 10% nitric acid aqueous solution were added, and the base material was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry e)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55 g of powder carrying 0.6 wt% of rhodium, 44.45 g of zirconia base material, 11 g of alumina base material (composite of γ-alumina with cerium oxide 9 wt%, zirconium oxide wt 6%, lanthanum oxide 6 wt%), 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier having a diameter of 36 mmφ and a 400 cell 6 mil (capacity 0.04 L) was coated with 141 g / L of slurry e and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. The sample of Example 5 was obtained.
得られた実施例５の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 5 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[実施例６]
６０×１０ｎｍのベーマイトを用いた、セリア２０ｗｔ％入り触媒の調製
ベーマイト（６０×１０ｎｍ）に酢酸セリウムを含浸、乾燥し、酸化セリウムとして２０ｗｔ％含むアルミナ基材（水分を２３％ｗｔ含有）を調製した。このアルミナ基材２５８．６５ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ５に調整した。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Example 6]
Preparation of catalyst containing 20 wt% ceria using 60 × 10 nm boehmite Boehmite (60 × 10 nm) is impregnated with cerium acetate and dried to prepare an alumina substrate (containing 23% wt water) as cerium oxide did. 258.65 g of this alumina substrate was dispersed in 2000 ml of water, and nitric acid was added to adjust the pH to 5. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｆ）
この粉末Ｆについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により前記実施例１〜５と同様の露出率を求めたところ、９８％であった。
This slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder F)
For this powder F, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by a gas adsorption method, and the same exposure rate as in Examples 1 to 5 was determined by observation with a TEM (transmission electron microscope). 98%.
粉末Ｆを１７３．４ｇと、アルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｆ）
次に、ジルコニウムを３ｗｔ％含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｆを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例６の試料とした。
173.4 g of powder F, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the base material was pulverized to obtain a slurry having an average particle size of 3 μm. (Slurry f)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% of zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% of rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55 g of a powder carrying 0.6 wt% rhodium and 44.45 g of a zirconia base material, 11 g of an alumina base material (composite of γ-alumina with 9 wt% cerium oxide, 6 wt% zirconium oxide and 6 wt% lanthanum oxide), 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and a 400 cell 6 mil was coated with 141 g / L of slurry f and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. The sample of Example 6 was obtained.
得られた実施例６の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 6 is a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[実施例７]
６０×１０ｎｍのベーマイトを用いた、酸化マンガン粒子２０ｗｔ％入り触媒の調製
ベーマイト（６０×１０ｎｍ）を分散した水溶液に、酸化マンガン（Ｍｎ３Ｏ４）粒子を加えて乾燥し、酸化マンガンを２０ｗｔ％含むアルミナ基材（水分が２３ｗｔ％含有）を調製した。このアルミナ基材２５８．６５ｇを水２０００ｍｌに分散させ、硝酸を加えてｐＨ４に調整した。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Example 7]
Preparation of catalyst containing manganese oxide particles 20 wt% using boehmite of 60 × 10 nm To an aqueous solution in which boehmite (60 × 10 nm) is dispersed, manganese oxide (Mn 3 O 4 ) particles are added and dried, and manganese oxide is 20 wt%. An alumina substrate containing (containing 23 wt% of water) was prepared. 258.65 g of this alumina substrate was dispersed in 2000 ml of water, and nitric acid was added to adjust the pH to 4. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをスプレードライヤを用いて乾燥し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｇ）
この粉末Ｇについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）により、前記実施例１〜６と同様に露出率を求めたところ、８５％であった。
This slurry was dried using a spray dryer and fired at 400 ° C. to obtain a Pt-supported sample. (Powder G)
For this powder G, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by a gas adsorption method, and the exposure rate was determined by TEM (transmission electron microscope) in the same manner as in Examples 1 to 6, It was 85%.
粉末Ｇを１７３．４ｇと、アルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径３μｍのスラリーとした。（スラリーｇ）
次に、ジルコニウムを３ｗｔ％含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｇを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して実施例７の試料とした。
173.4 g of powder G, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the base material was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry g)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% of zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% of rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55 g of a powder carrying 0.6 wt% rhodium and 44.45 g of a zirconia base material, 11 g of an alumina base material (composite of γ-alumina with 9 wt% cerium oxide, 6 wt% zirconium oxide and 6 wt% lanthanum oxide), 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier having a diameter of 36 mmφ and a 400 cell 6 mil (capacity 0.04 L) was coated with 141 g / L of slurry g and then dried, then 59 g / L of slurry R was coated, dried, and fired at 400 ° C. A sample of Example 7 was obtained.
得られた実施例７の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Example 7 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[比較例１]
１０μｍ×１０μｍのアルミナ粒子を用いた触媒の調製
粒子径が１０μｍのγ−アルミナ基材１９９．１６ｇにジニトロジアミンＰｔ溶液（Ｐｔを０．８４ｇ含む）を含浸し、乾燥後、４００℃で焼成してＰｔ担持試料とした。（粉末Ｈ）
この粉末Ｈについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により、前記実施例１〜７と同様に露出率を求めると、１３４％であった。
[Comparative Example 1]
Preparation of catalyst using 10 μm × 10 μm alumina particles 199.16 g of a γ-alumina substrate having a particle size of 10 μm was impregnated with a dinitrodiamine Pt solution (containing 0.84 g of Pt), dried and calcined at 400 ° C. Thus, a Pt-supported sample was obtained. (Powder H)
For this powder H, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by gas adsorption, and the exposure rate was determined in the same manner as in Examples 1 to 7 by observation with a TEM (transmission electron microscope). 134%.
粉末Ｈを１７３．４ｇと、アルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｈ）
次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウム０．６ｗｔ％を担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウム０．６ｗｔ％を担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーＩを１４１ｇ／Ｌコーティングし、乾燥後、さらに実施例１で調製したスラリーＲを５９ｇ／Ｌコーティングし、乾燥後４００℃で焼成して、比較例１の試料とした。
173.4 g of powder H, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the base material was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry h)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% as zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55 g of powder carrying 0.6 wt% rhodium, 44.45 g of zirconia base material, 11 g of alumina base material (composite of γ-alumina with 9 wt% cerium oxide, 6 wt% zirconium oxide, 6 wt% lanthanum oxide), 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and 400 cells 6 mil was coated with 141 g / L of slurry I, dried, and further coated with 59 g / L of slurry R prepared in Example 1, and dried at 400 ° C. The sample of Comparative Example 1 was fired.
得られた比較例１の触媒はＰｔ：０．５８７ｇ／Ｌ、Ｒｈ：０．２３６ｇ／Ｌを担持した触媒である。 The obtained catalyst of Comparative Example 1 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[比較例２]
１０μｍ×１０μｍのアルミナ粒子を用いた、酸化セリウム（２０ｗｔ％）入り触媒の調製
γ−アルミナ（粒子径：１０μｍ）に酢酸セリウムを含浸し、乾燥後、６００℃で焼成して、酸化セリウムを２０ｗｔ％含むアルミナ基材を調製した。このアルミナ基材１９９．１６ｇにジニトロジアミンＰｔ溶液（Ｐｔを０．８４ｇ含む）を含浸し、乾燥後、４００℃で焼成してＰｔ担持試料とした。（粉末Ｉ）
この粉末Ｉについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により、前記実施例１〜比較例１と同様に露出率を求めると、１５２％であった。
[Comparative Example 2]
Preparation of catalyst containing cerium oxide (20 wt%) using alumina particles of 10 μm × 10 μm γ-alumina (particle diameter: 10 μm) was impregnated with cerium acetate, dried and calcined at 600 ° C. to give 20 wt of cerium oxide. % Alumina substrate was prepared. 199.16 g of this alumina substrate was impregnated with a dinitrodiamine Pt solution (containing 0.84 g of Pt), dried, and then fired at 400 ° C. to obtain a Pt-supported sample. (Powder I)
For this powder I, the amount of CO adsorbed per unit weight (that is, 1 g) was determined by a gas adsorption method, and the exposure rate was determined in the same manner as in Examples 1 to 1 by observation with a TEM (transmission electron microscope). When calculated, it was 152%.
粉末Ｉを１７３．４ｇと、アルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｉ）
次に、ジルコニウムとして３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径が３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｊを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して比較例２の試料とした。
173.4 g of powder I, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the substrate was pulverized to obtain a slurry having an average particle size of 3 μm. (Slurry i)
Next, rhodium nitrate was impregnated with a composite compound of γ-alumina and zirconium oxide containing 3 wt% as zirconium to prepare 0.6 wt% rhodium supported powder. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55 g of a powder carrying 0.6 wt% rhodium and 44.45 g of a zirconia base material, 11 g of an alumina base material (composite of γ-alumina with 9 wt% cerium oxide, 6 wt% zirconium oxide and 6 wt% lanthanum oxide), 3 g of alumina sol was added to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle size of 3 μm. (Slurry R)
A honeycomb carrier having a diameter of 36 mmφ and a 400 cell 6 mil (capacity 0.04 L) was coated with 141 g / L of slurry j and then dried, then 59 g / L of slurry R was coated, dried and fired at 400 ° C. A sample of Comparative Example 2 was obtained.
得られた比較例２の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Comparative Example 2 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[比較例３]
１０μｍ×１０μｍのアルミナ粒子を用いた、酸化マンガン（２０ｗｔ％）入り触媒の調製
γ−アルミナ（粒子径が１０μｍ）に酢酸マンガンを含浸し、乾燥後、６００℃で焼成して、酸化マンガン（Ｍｎ３Ｏ４）を２０ｗｔ％含むアルミナ基材を調製した。このアルミナ基材１９９．１６ｇにジニトロジアミンＰｔ溶液（Ｐｔを０．８４ｇ含む）を含浸し、乾燥後、４００℃で焼成してＰｔ担持試料とした。（粉末Ｊ）
この粉末Ｊについてガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により、前記実施例１〜比較例２と同様に露出率を求めると、１３５％であった。
[Comparative Example 3]
Preparation of a catalyst containing manganese oxide (20 wt%) using 10 μm × 10 μm alumina particles γ-alumina (particle diameter is 10 μm) is impregnated with manganese acetate, dried, and calcined at 600 ° C. to produce manganese oxide (Mn An alumina substrate containing 20 wt% of 3 O 4 ) was prepared. 199.16 g of this alumina substrate was impregnated with a dinitrodiamine Pt solution (containing 0.84 g of Pt), dried, and then fired at 400 ° C. to obtain a Pt-supported sample. (Powder J)
For this powder J, the amount of CO adsorbed per unit weight (ie, 1 g) was determined by a gas adsorption method, and the exposure rate was determined in the same manner as in Examples 1 and 2 by observation with a TEM (transmission electron microscope). When calculated, it was 135%.
粉末Ｊを１７３．４ｇと、アルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径３μｍのスラリーとした。（スラリーｊ）
次に、ジルコニウムを３ｗｔ％を含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウムを０．６ｗｔ％担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウムを０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径が３μｍのスラリーとした。（スラリーＲ）
直径が３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｋを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して比較例３の試料とした。
173.4 g of powder J, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the base material was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry j)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116.55 g of a powder carrying 0.6 wt% rhodium and 44.45 g of a zirconia base material, 11 g of an alumina base material (composite of γ-alumina with 9 wt% cerium oxide, 6 wt% zirconium oxide and 6 wt% lanthanum oxide), 3 g of alumina sol was added to a ball mill, and 307.5 g of water and 17.5 g of 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and 400 cells 6 mil was coated with 141 g / L of slurry k and dried, and then coated with 59 g / L of slurry R, dried, and fired at 400 ° C. Thus, a sample of Comparative Example 3 was obtained.
得られた比較例３の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Comparative Example 3 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[比較例４]
５×５ｎｍの水酸化アルミニウムを用いた触媒の調製
水酸化アルミニウム（５×５ｎｍ、含水率３４．６％）３０４．５３ｇを水２０００ｍｌに分散させた。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Comparative Example 4]
Preparation of catalyst using 5 × 5 nm aluminum hydroxide 304.53 g of aluminum hydroxide (5 × 5 nm, water content 34.6%) was dispersed in 2000 ml of water. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをビーカー中で蒸発乾固し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｋ）
この粉末Ｋについて、ガス吸着法により、単位重量（１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により、前記実施例１〜比較例３と同様に露出率を求めたところ、７５％であった。
This slurry was evaporated to dryness in a beaker and fired at 400 ° C. to obtain a Pt-supported sample. (Powder K)
For this powder K, the amount of CO adsorbed per unit weight (1 g) was determined by the gas adsorption method, and the exposure rate was determined in the same manner as in Examples 1 to 3 by observation with a TEM (transmission electron microscope). As a result, it was 75%.
粉末Ｋを１７３．４ｇと、アルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径が３μｍのスラリーとした。（スラリーｋ）
次に、ジルコニウムを３ｗｔ％含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウム０．６ｗｔ％担持粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウム０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｋを１４１ｇ／Ｌ コーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌコーティングし、乾燥後、４００℃で焼成して比較例４の試料とした。
173.4 g of powder K, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the base material was pulverized to obtain a slurry having an average particle size of 3 μm. (Slurry k)
Next, rhodium nitrate was impregnated into a composite compound of γ-alumina and zirconium oxide containing 3 wt% zirconium to prepare a 0.6 wt% rhodium supported powder. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116 g of rhodium-supported powder 116.55 g, 44.45 g of zirconia base material, 11 g of alumina base material (composite of γ-alumina with cerium oxide 9 wt%, zirconium oxide 6 wt%, lanthanum oxide 6 wt%), alumina sol 3 g was added to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and a 400 cell 6 mil was coated with 141 g / L of slurry k, dried, and then coated with 59 g / L of slurry R, dried, and fired at 400 ° C. A sample of Comparative Example 4 was obtained.
得られた比較例４の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Comparative Example 4 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[比較例５]
３００×２０ｎｍのベーマイトを用いた触媒の調製
ベーマイト（３００×２０ｎｍ、含水率２６％）２６９．１４ｇを水２０００ｍｌに分散させた。これにＰｔを０．８４ｇ含むＰｔコロイドを加え分散させた。このＰｔコロイドは、Ｐｔ粒子径：２．６ｎｍ、保護コロイド：ポリビニールピロリドン（ＰＶＰ）であった。
[Comparative Example 5]
Preparation of catalyst using 300 × 20 nm boehmite 269.14 g of boehmite (300 × 20 nm, water content 26%) was dispersed in 2000 ml of water. To this, a Pt colloid containing 0.84 g of Pt was added and dispersed. This Pt colloid was Pt particle size: 2.6 nm and protective colloid: polyvinylpyrrolidone (PVP).
このスラリーをビーカー中で蒸発乾固し、４００℃で焼成してＰｔ担持試料とした。（粉末Ｌ）
この粉末Ｌについて、ガス吸着法により、単位重量（即ち、１ｇ）あたりのＣＯ吸着量を求め、またＴＥＭ（透過型電子顕微鏡）による観察により、前記実施例１〜比較例４と同様に露出率を求めたところ、１１０％であった。
This slurry was evaporated to dryness in a beaker and fired at 400 ° C. to obtain a Pt-supported sample. (Powder L)
About this powder L, the amount of CO adsorption per unit weight (that is, 1 g) was determined by a gas adsorption method, and the exposure rate was the same as in Examples 1 to 4 by observation with a TEM (transmission electron microscope). Was 110%.
粉末Ｌを１７３．４ｇとアルミナゾル１．６ｇ、更に水３０７．５ｇ、１０％硝酸水溶液を１７．５ｇ加えて、基材の粉砕を行い、平均粒径３μｍのスラリーとした。（スラリーｌ）
次に、ジルコニウムを３ｗｔ％含むγ−アルミナと酸化ジルコニウムの複合化合物に硝酸ロジウムを含浸して、ロジウム０．６ｗｔ％を担持した粉末を調製した。また、酸化ジルコニウムに酸化セリウムを２４ｗｔ％複合化し、ジルコニア基材を調製した。ロジウム０．６ｗｔ％担持した粉末１１６．５５ｇとジルコニア基材４４．４５ｇ、アルミナ基材
（γ−アルミナに酸化セリウム９ｗｔ％、酸化ジルコニウム６ｗｔ％、酸化ランタン６ｗｔ％を複合化したもの）１１ｇ、アルミナゾル３ｇをボールミルに加え、水３０７．５ｇ、１０ｗｔ％硝酸水溶液１７．５ｇを加えて粉砕し、平均粒径３μｍのスラリーとした。（スラリーＲ）
直径３６ｍｍφ、４００セル６ミルのハニカム担体（容量０．０４Ｌ）にスラリーｋを１４１ｇ／Ｌコーティングした後、乾燥し、その後、スラリーＲを５９ｇ／Ｌ コーティングし、乾燥後、４００℃で焼成して比較例５の試料とした。
173.4 g of powder L, 1.6 g of alumina sol, 307.5 g of water, and 17.5 g of 10% nitric acid aqueous solution were added, and the substrate was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry l)
Next, a composite compound of γ-alumina and zirconium oxide containing 3 wt% of zirconium was impregnated with rhodium nitrate to prepare a powder carrying 0.6 wt% of rhodium. Moreover, 24 wt% of cerium oxide was combined with zirconium oxide to prepare a zirconia base material. 116 g of rhodium supported powder 116.55 g, 44.45 g of zirconia base material, 11 g of alumina base material (composite of γ-alumina 9 wt% cerium oxide, 6 wt% zirconium oxide, 6 wt% lanthanum oxide), alumina sol 3 g was added to a ball mill, 307.5 g of water and 17.5 g of a 10 wt% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry R)
A honeycomb carrier (capacity 0.04 L) having a diameter of 36 mmφ and a 400 cell 6 mil was coated with 141 g / L of slurry k and then dried, and then coated with 59 g / L of slurry R, dried and fired at 400 ° C. A sample of Comparative Example 5 was obtained.
得られた比較例５の触媒は、Ｐｔ：０．５８７ｇ／Ｌ，Ｒｈ：０．２３６ｇ／Ｌを各々担持した触媒である。 The obtained catalyst of Comparative Example 5 was a catalyst carrying Pt: 0.587 g / L and Rh: 0.236 g / L.
[耐久試験]
排気量が３５００ｃｃのＶ型エンジンの排気系に、片バンクあたり前記実施例１〜比較例５で得られた排気ガス浄化用触媒を５個ずつ装着し、国内レギュラーガソリンを使用し、触媒入口温度を６５０℃とし、３０時間運転する耐久試験を実施した。
[An endurance test]
The exhaust system of a V-type engine with a displacement of 3500 cc is equipped with five exhaust gas purifying catalysts obtained in Examples 1 to 5 per bank, using regular domestic gasoline, and the catalyst inlet temperature. Was subjected to a durability test at a temperature of 650 ° C. and operated for 30 hours.
[浄化性能試験]
前述の比較例及び実施例にて調製した各触媒について耐久試験を実施した後、各触媒を模擬排気ガス流通装置に組み込み、以下の表２に示す組成の模擬排気ガスを流通させ、触媒温度を５℃／分の速度で昇温させながら、ＮＯｘ、ＣＯ、ＨＣの浄化率が５０％になる温度を調べた。この評価結果を前述した表１にまとめて示す。
After carrying out a durability test on each catalyst prepared in the comparative examples and examples described above, each catalyst was incorporated into a simulated exhaust gas circulation device, and a simulated exhaust gas having the composition shown in Table 2 below was circulated. While raising the temperature at a rate of 5 ° C./min, the temperature at which the NOx, CO, and HC purification rates were 50% was examined. The evaluation results are summarized in Table 1 described above.
比較例１の試料は、γアルミナにＰｔを含浸担持した触媒である。比較例２の試料は、セリア入りアルミナ基材にＰｔを含浸担持した触媒である。比較例３の試料は、酸化マンガン入りアルミナ基材にＰｔを含浸担持した試料である。比較例４の試料は、内包材５として粒子径が小さいアルミナ前駆体を使用して調製した試料であるが、乾燥方法はビーカーによる蒸発乾固法を採用している。比較例５は、内包材５として粒子径が大きいアルミナ前駆体を使用して調製した試料であるが、比較例４と同様乾燥方法はビーカーによる蒸発乾固法を採用している。 The sample of Comparative Example 1 is a catalyst in which Pt is impregnated and supported on γ alumina. The sample of Comparative Example 2 is a catalyst obtained by impregnating and supporting Pt on an alumina base material containing ceria. The sample of Comparative Example 3 is a sample obtained by impregnating and supporting Pt on an alumina base material containing manganese oxide. The sample of Comparative Example 4 is a sample prepared using an alumina precursor having a small particle size as the inner packaging material 5, and the evaporation method using a beaker is adopted as the drying method. Comparative Example 5 is a sample prepared using an alumina precursor having a large particle size as the encapsulating material 5, and the drying method is the evaporation method using a beaker as in Comparative Example 4.
耐久試験が終了した比較例１の触媒の第一層（内層）を掻き取り、ＴＥＭによりＰｔ粒子径を調べたところ、３０ｎｍであった。また、比較例２では、Ｐｔ粒子径は１５ｎｍであった。これは、ＣｅＯ２のアンカー効果により、Ｐｔ粒子径が小さく抑えられたものである。比較例３では、Ｐｔ粒子径を調べたところ２８ｎｍであり、比較例１と大差は見られなかった。比較例４では、Ｐｔ粒子径は２０ｎｍであり、比較例１に較べて小さかった。また、比較例５では、Ｐｔ粒子径は３５ｎｍであり比較例１に較べて大きかった。実施例１〜７の試料では、Ｐｔ粒子径はいずれも比較例１に比べて小さく１５〜２０ｎｍであった。 The first layer (inner layer) of the catalyst of Comparative Example 1 for which the durability test was completed was scraped, and the Pt particle diameter was examined by TEM. As a result, it was 30 nm. In Comparative Example 2, the Pt particle size was 15 nm. This is because the Pt particle diameter is kept small by the anchor effect of CeO 2 . In Comparative Example 3, when the Pt particle diameter was examined, it was 28 nm, which was not significantly different from Comparative Example 1. In Comparative Example 4, the Pt particle size was 20 nm, which was smaller than that of Comparative Example 1. In Comparative Example 5, the Pt particle size was 35 nm, which was larger than that of Comparative Example 1. In the samples of Examples 1 to 7, the Pt particle size was 15 to 20 nm, which was smaller than that of Comparative Example 1.
なお、実施例の初期の状態を確認するため、実施例２で調製した粉末ＢについてＴＥＭで観察したところ、図５に示すように、Ｐｔ粒子が内包材５であるアルミナ粒子でケージ状に覆われていることが確認された。なお、図５は、ミクロトームにより粉末Ｂ（実施例２参照）を切断し、その切断した断面を示したＴＥＭ像である。 In order to confirm the initial state of the example, the powder B prepared in Example 2 was observed with a TEM. As shown in FIG. 5, the Pt particles were covered in a cage shape with alumina particles as the inclusion material 5. It was confirmed that FIG. 5 is a TEM image showing a cut section of the powder B (see Example 2) cut by a microtome.
比較例１〜３では、初期のＰｔ粒子はアルミナ等の粒子の表面に付着している。このため、Ｐｔ粒子が移動し易く、凝集し易い状態となっている。この場合、露出率は１００％以上となり、ガス吸着法でのＣＯ吸着量がＴＥＭによる平均Ｐｔ粒子径から算出したＣＯ吸着量より大きいことを示している。ＴＥＭにおいては、オングストロームレベルのＰｔ粒子は検出しにくく、概ねｎｍレベルのＰｔ粒子を観察している。これに対し、ガス吸着法では、オングストロームレベルも含め全てのＰｔ粒子に吸着したＣＯ量が得られる。比較例１〜３では、前述のオングストロームレベルのＰｔ粒子が基材の表面に存在しているため、Ｐｔ粒子数も多くなり、Ｐｔ粒子とＰｔ粒子の間隔が近くなっている。これにより、Ｐｔ粒子は凝集しやすくなっており、実際、前述の実施例１〜３のように耐久試験後のＰｔ粒子径は大きいことが確認されている。 In Comparative Examples 1 to 3, the initial Pt particles are attached to the surface of particles such as alumina. For this reason, the Pt particles are easy to move and aggregate. In this case, the exposure rate is 100% or more, indicating that the CO adsorption amount by the gas adsorption method is larger than the CO adsorption amount calculated from the average Pt particle diameter by TEM. In TEM, angstrom-level Pt particles are difficult to detect, and nm-level Pt particles are generally observed. In contrast, in the gas adsorption method, the amount of CO adsorbed on all Pt particles including the angstrom level can be obtained. In Comparative Examples 1 to 3, since the angstrom-level Pt particles described above are present on the surface of the substrate, the number of Pt particles is increased, and the interval between the Pt particles and the Pt particles is reduced. As a result, the Pt particles are easily aggregated, and it has been confirmed that the Pt particle diameter after the durability test is actually large as in Examples 1 to 3 described above.
しかし、実施例では、実施例２のようにＰｔ粒子が内包材５となるアルミナ等の粒子により覆われているため、Ｐｔ粒子が移動する際の障壁となって、Ｐｔ粒子の凝集を抑制している。 However, in the example, since the Pt particles are covered with the particles of alumina or the like serving as the inner packaging material 5 as in Example 2, it becomes a barrier when the Pt particles move and suppresses the aggregation of the Pt particles. ing.
また、実施例６の試料にはＣｅＯ２が含まれるが、同様にＣｅＯ２が含まれる比較例２に較べてＰｔ粒子径は１０ｎｍと小さかった。これは、ＣｅＯ２によるアンカー効果、及び、前述のアルミナ粒子によるケージ状構造によりＰｔの移動が抑制されたことによるものと考えられる。 Further, the sample of Example 6 but contains CeO 2, Pt particle size as compared with Comparative Example 2 containing the same manner CeO 2 was as small as 10 nm. This is thought to be due to the Pt movement being suppressed by the anchor effect of CeO 2 and the cage structure of the alumina particles described above.
実施例では、露出率は１００％以下となっているが、これはＰｔ粒子をアルミナ等の粒子（内包材５）が覆っており、ケージ状構造を形成しているため、ＣＯを吸着しにくくなっていることによるものと考えられる。 In the example, the exposure rate is 100% or less. This is because the Pt particles are covered with particles such as alumina (encapsulation material 5) and form a cage structure, so that it is difficult to adsorb CO. This is thought to be due to
実施例７では、Ｐｔ粒子径は２０ｎｍとさほど小さくはないが、触媒性能としては良くなっている。これは、酸化マンガンが添加されているため、マンガンの酸素放出能によるものと考えられる。 In Example 7, the Pt particle size is not so small as 20 nm, but the catalyst performance is improved. This is considered to be due to the oxygen releasing ability of manganese because manganese oxide is added.
比較例３についても比較例１に較べて触媒性能が良くなっており、マンガンの酸素放出能によるものと考えられる。 The catalyst performance of Comparative Example 3 is also better than that of Comparative Example 1, which is considered to be due to the oxygen releasing ability of manganese.
比較例４では、Ｐｔ粒子径が小さかったが、性能は劣っていた。これは、初期のＰｔの露出率が７５％と小さく、Ｐｔ粒子が基材に埋もれた状態に近く、また耐久試験後ではアルミナ等の基材にＰｔ粒子が埋もれてしまい、Ｐｔ粒子の凝集は抑えられたが、排気ガス成分がＰｔ粒子と接触できなくなってしまい、性能も低下したものと考えられる。 In Comparative Example 4, the Pt particle size was small, but the performance was inferior. This is because the initial Pt exposure rate is as small as 75%, and the Pt particles are close to the state of being buried in the base material, and after the durability test, the Pt particles are buried in the base material such as alumina. Although suppressed, it is considered that the exhaust gas component cannot contact the Pt particles, and the performance is also deteriorated.
比較例５では、Ｐｔ粒子径が大きかったが、これは、アルミナ一次粒子が大きいため、内包材５であるアルミナ粒子上にＰｔが付着したことによるもの、及び、内包材５が大きすぎてケージ状構造が形成できなかったことによるものと考えられる。 In Comparative Example 5, the Pt particle diameter was large. This is due to the fact that the primary alumina particles were large, so that Pt adhered to the alumina particles as the inner packaging material 5, and the inner packaging material 5 was too large. This is thought to be due to the failure to form the structure.
１ 排気ガス浄化用触媒
３ 貴金属粒子
５ 内包材
７ Ｐｔコロイド（貴金属コロイド）
１１ アルミナ前駆体
DESCRIPTION OF SYMBOLS 1 Exhaust gas purification catalyst 3 Noble metal particle 5 Encapsulation material 7 Pt colloid (noble metal colloid)
11 Alumina precursor
Claims (8)
下記算出式で算出される露出率が８５％以上１００％未満であることを特徴とする排気ガス浄化用触媒。
露出率＝（貴金属粒子の周囲を内包材で覆った触媒にガス吸着法によりＣＯガスを接触させたときのＣＯ吸着量）÷（ＴＥＭ観察によって測定された貴金属粒子の表面積に基づいて算出されたＣＯ吸着量）×１００ Comprising noble metal particles, a plurality of particles formed in a fibrous form, comprising an inner packaging material surrounding the noble metal particles, and a base material carrying the noble metal particles surrounded by the inner packaging material, The size of the gap formed by the inner packaging material is set smaller than the diameter of the noble metal particles,
An exhaust gas purification catalyst characterized in that an exposure rate calculated by the following calculation formula is 85% or more and less than 100%.
Exposure rate = (CO adsorption amount when CO gas is brought into contact with a catalyst in which the periphery of the noble metal particles is covered with an inclusion material by the gas adsorption method) ÷ (calculated based on the surface area of the noble metal particles measured by TEM observation) CO adsorption amount) x 100
アルミナ前駆体を水に分散し、解膠する工程と、このアルミナ前駆体の分散液中に、貴金属コロイドを分散させたのち、乾燥し、焼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 an exhaust gas purifying catalyst according to claim 1 or 2,
Exhaust gas purification comprising a step of dispersing an alumina precursor in water and peptizing, and a step of dispersing a precious metal colloid in the alumina precursor dispersion, followed by drying and firing. For producing a catalyst for use.
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