JP3362532B2 - Exhaust gas purification catalyst and method for producing the same - Google Patents
Exhaust gas purification catalyst and method for producing the sameInfo
- Publication number
- JP3362532B2 JP3362532B2 JP30626594A JP30626594A JP3362532B2 JP 3362532 B2 JP3362532 B2 JP 3362532B2 JP 30626594 A JP30626594 A JP 30626594A JP 30626594 A JP30626594 A JP 30626594A JP 3362532 B2 JP3362532 B2 JP 3362532B2
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- ceria
- solid solution
- cerium oxide
- coat layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000003054 catalyst Substances 0.000 title claims description 62
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 238000000746 purification Methods 0.000 title claims description 9
- 239000006104 solid solution Substances 0.000 claims description 38
- 239000002245 particle Substances 0.000 claims description 35
- 239000010410 layer Substances 0.000 claims description 31
- 239000002002 slurry Substances 0.000 claims description 25
- 239000000843 powder Substances 0.000 claims description 24
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 23
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 23
- 239000000758 substrate Substances 0.000 claims description 15
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims description 14
- 229910001928 zirconium oxide Inorganic materials 0.000 claims description 14
- 230000003197 catalytic effect Effects 0.000 claims description 12
- 229910000510 noble metal Inorganic materials 0.000 claims description 11
- 239000011248 coating agent Substances 0.000 claims description 7
- 238000000576 coating method Methods 0.000 claims description 7
- 238000010304 firing Methods 0.000 claims description 7
- 239000000243 solution Substances 0.000 claims description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 4
- 239000011247 coating layer Substances 0.000 claims description 4
- 150000003755 zirconium compounds Chemical class 0.000 claims description 3
- 229910052763 palladium Inorganic materials 0.000 claims description 2
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 66
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 66
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 56
- 239000007789 gas Substances 0.000 description 47
- 230000000694 effects Effects 0.000 description 29
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 21
- 239000001301 oxygen Substances 0.000 description 21
- 229910052760 oxygen Inorganic materials 0.000 description 21
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 19
- 238000003860 storage Methods 0.000 description 17
- 238000000034 method Methods 0.000 description 15
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 10
- 239000011148 porous material Substances 0.000 description 8
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 7
- 229910002091 carbon monoxide Inorganic materials 0.000 description 7
- 230000007423 decrease Effects 0.000 description 7
- 239000010948 rhodium Substances 0.000 description 7
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 229910052697 platinum Inorganic materials 0.000 description 6
- 239000004215 Carbon black (E152) Substances 0.000 description 5
- 229910052878 cordierite Inorganic materials 0.000 description 5
- 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 5
- 229930195733 hydrocarbon Natural products 0.000 description 5
- 150000002430 hydrocarbons Chemical class 0.000 description 5
- 229910052703 rhodium Inorganic materials 0.000 description 5
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 229910001593 boehmite Inorganic materials 0.000 description 4
- 239000000084 colloidal system Substances 0.000 description 4
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000004584 weight gain Effects 0.000 description 4
- 235000019786 weight gain Nutrition 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 150000004645 aluminates Chemical class 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000003426 co-catalyst Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000011156 evaluation 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
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 210000001217 buttock Anatomy 0.000 description 1
- -1 ceria aluminate Chemical class 0.000 description 1
- 150000001785 cerium compounds Chemical class 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- SONJTKJMTWTJCT-UHFFFAOYSA-K rhodium(iii) chloride Chemical compound [Cl-].[Cl-].[Cl-].[Rh+3] SONJTKJMTWTJCT-UHFFFAOYSA-K 0.000 description 1
- 239000012266 salt solution Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- 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
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- 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
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車などの内燃機関
から排出される排ガス中に含まれる炭化水素（ＨＣ）、
一酸化炭素（ＣＯ）及び窒素酸化物（ＮＯx ）の三成分
を浄化する排ガス浄化用触媒とその製造方法に関し、さ
らに詳しくは、自動車排ガスなどの酸化雰囲気と還元雰
囲気をくり返す変動条件下においても前記三成分を効率
良く浄化でき、耐熱性に優れた排ガス浄化用触媒とその
製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrocarbon (HC) contained in exhaust gas discharged from an internal combustion engine of an automobile,
The present invention relates to an exhaust gas-purifying catalyst for purifying three components of carbon monoxide (CO) and nitrogen oxide (NO x ), and a method for producing the same. Relates to an exhaust gas-purifying catalyst excellent in heat resistance and capable of efficiently purifying the above three components, and a method for producing the same.
【０００２】[0002]
【従来の技術】従来より、自動車の排ガス浄化用触媒と
して、ＣＯ及びＨＣの酸化とＮＯx の還元とを同時に行
って排ガスを浄化する三元触媒が用いられている。この
ような三元触媒としては、例えばコーディエライトなど
からなる耐熱性基材にγ−アルミナからなる多孔質担体
層を形成し、その多孔質担体層に白金（Ｐｔ）、ロジウ
ム（Ｒｈ）などの触媒貴金属を担持させたものが広く知
られている。2. Description of the Related Art Conventionally, a three-way catalyst for purifying exhaust gas by simultaneously oxidizing CO and HC and reducing NO x has been used as a catalyst for purifying exhaust gas of automobiles. As such a three-way catalyst, for example, a porous carrier layer made of γ-alumina is formed on a heat resistant base material made of cordierite, and platinum (Pt), rhodium (Rh), etc. are formed on the porous carrier layer. A catalyst carrying a noble metal is widely known.
【０００３】また近年では、例えば特公昭５８−２０３
０７号公報に開示されているように、酸素貯蔵効果をも
つセリウム酸化物（セリア）を助触媒として併用し、低
温活性を高めた三元触媒も知られている。助触媒として
のセリアを多孔質担体に担持させるには、例えばアルミ
ナからなるコート層をもつモノリス担体に硝酸セリウム
などのセリウム化合物水溶液を吸水させ、それを焼成す
るいわゆる含浸担持法と、含浸担持法の改良として例え
ば特開昭６０−１１０３３４号公報に開示されているよ
うにセリア粉末をアルミナなどの多孔質担体粉末と混合
するいわゆる粉末担持法が知られている。In recent years, for example, Japanese Patent Publication No. 58-203.
As disclosed in Japanese Patent Application Laid-Open No. 07-2007, there is also known a three-way catalyst in which cerium oxide (ceria) having an oxygen storage effect is also used as a co-catalyst to enhance low temperature activity. In order to support ceria as a co-catalyst on a porous carrier, for example, a so-called impregnation supporting method in which a monolith carrier having a coat layer made of alumina absorbs an aqueous solution of a cerium compound such as cerium nitrate and calcined it, and an impregnation supporting method. the so-called powder-carrying method is known in which ceria powder as disclosed as an improvement example in JP 60-110 3 34 No. of mixing a porous carrier powder such as alumina.
【０００４】[0004]
【発明が解決しようとする課題】含浸担持法によれば、
セリアは１ｎｍ以下の極めて粒径の小さな微粒子となっ
て高分散で担持させることができる。したがって得られ
た排ガス浄化用触媒では上記したセリアの酸素貯蔵効果
を最大に発揮できるように思われるが、現実にはセリア
の大部分が多孔質担体の細孔内に担持されるため、細孔
が閉塞されて触媒の比表面積が低下するという問題があ
る。またセリアは細孔の奥深くに吸収担持されているの
で、排ガスと接触する機会が少なくなり酸素貯蔵効果が
有効に機能しないという不具合がある。さらに、高分散
担持されたセリアは多孔質担体との接触面積が大きくな
り、多孔質担体がアルミナの場合にはアルミナと反応し
やすく、セリア・アルミネート（ＣｅＡｌＯ3 ）が生成
してさらに触媒の比表面積が低下するという問題もあっ
た。According to the impregnating and supporting method,
Ceria becomes fine particles having an extremely small particle size of 1 nm or less and can be supported with high dispersion. Therefore, it seems that the obtained exhaust gas-purifying catalyst can maximize the oxygen storage effect of ceria described above, but in reality, most of ceria is supported in the pores of the porous carrier, However, there is a problem that the specific surface area of the catalyst is reduced due to the clogging. Also, since ceria is absorbed and supported deep inside the pores, there is a problem that the chance of contact with exhaust gas is reduced and the oxygen storage effect does not function effectively. Furthermore, the highly dispersed and supported ceria has a large contact area with the porous carrier, and when the porous carrier is alumina, it easily reacts with alumina, and ceria aluminate (CeAlO 3 ) is generated to further promote the catalyst formation. There is also a problem that the specific surface area decreases.
【０００５】一方、粉末担持法では、セリア粉末の平均
粒径は５００ｎｍ以上と大きいために、排ガスと接触す
るセリア粉末の比表面積が小さくなって、酸素の貯蔵・
放出による排ガスの雰囲気を一定に保つというセリアの
酸素貯蔵効果が必ずしも十分でないという問題がある。
すなわち、セリアは含浸担持法及び粉末担持法のいずれ
の方法で担持されても、酸素貯蔵効果が十分発揮でき
ず、得られた排ガス浄化用触媒は三元触媒としての活性
が不十分であった。On the other hand, in the powder carrying method, since the average particle size of the ceria powder is as large as 500 nm or more, the specific surface area of the ceria powder that comes into contact with the exhaust gas becomes small, so that oxygen storage and
There is a problem that the oxygen storage effect of ceria, which keeps the atmosphere of the exhaust gas due to release constant, is not always sufficient.
That is, ceria was not able to exert the oxygen storage effect sufficiently even if it was supported by either the impregnation supporting method or the powder supporting method, and the obtained exhaust gas purifying catalyst had insufficient activity as a three-way catalyst. .
【０００６】本発明はこのような事情に鑑みてなされた
ものであり、含浸担持法と粉末担持法で担持されたセリ
アのもつそれぞれの欠点を補い、セリアの酸素貯蔵効果
を最大に発揮させて三元活性を向上させることを目的と
する。The present invention has been made in view of the above circumstances, and compensates for the respective drawbacks of the ceria supported by the impregnation-supporting method and the powder-supporting method to maximize the oxygen storage effect of ceria. The purpose is to improve ternary activity.
【０００７】[0007]
【課題を解決するための手段】上記課題を解決する第１
発明の排ガス浄化用触媒は、多孔質担体と、多孔質担体
に担持された平均粒径が５〜１００ｎｍのセリウム酸化
物と、多孔質担体に担持されパラジウムを除く触媒貴金
属と、からなることを特徴とする。上記第１発明の排ガ
ス浄化用触媒をさらに改良する第２発明の排ガス浄化用
触媒は、多孔質担体と、多孔質担体に担持され互いに固
溶したセリウム酸化物及びジルコニウム酸化物よりなり
平均粒径が５〜１００ｎｍである固溶体と、多孔質担体
に担持された触媒貴金属とを含んで構成され、固溶体中
のセリウム酸化物のジルコニウム酸化物に対する固溶量
はモル比で０．２〜４．０であることを特徴とする。[Means for Solving the Problems] First to solve the above problems
Exhaust gas purifying catalyst of the invention comprises a porous support, and an average particle diameter that is supported on a porous support cerium oxide of 5 to 100 nm, and catalytic noble metal other than palladium supported on the porous carrier, in that it consists of Characterize. The exhaust gas purifying catalyst of the second invention, which is a further improvement of the exhaust gas purifying catalyst of the first invention, comprises a porous carrier and cerium oxide and zirconium oxide supported on the porous carrier and solid-solved with each other. Of 5 to 100 nm and a catalytic noble metal supported on a porous carrier, and the solid solution amount of cerium oxide to zirconium oxide in the solid solution is 0.2 to 4.0 in terms of molar ratio. Is characterized in that.
【０００８】また上記第１発明の排ガス浄化用触媒を製
造するのに最適な第３発明の排ガス浄化用触媒の製造方
法は、多孔質担体粉末とセリウム酸化物ゾルを含むスラ
リーを用いて担体基材表面にコートし焼成して平均粒径
が５〜１００ｎｍのセリウム酸化物を含むコート層を形
成する工程と、コート層に触媒貴金属を担持する工程
と、を含んで構成されることを特徴とする。The method for producing an exhaust gas-purifying catalyst of the third invention, which is most suitable for producing the exhaust gas-purifying catalyst of the above-mentioned first invention, uses a slurry containing a porous carrier powder and cerium oxide sol as a carrier base. And a step of forming a coat layer containing a cerium oxide having an average particle diameter of 5 to 100 nm by coating on the surface of the material and firing, and a step of supporting a catalytic noble metal on the coat layer. To do.
【０００９】さらに上記第２発明の排ガス浄化用触媒を
製造する第４発明の排ガス浄化用触媒の製造方法は、多
孔質担体粉末とセリウム酸化物ゾル及びジルコニウム酸
化物（ジルコニア）ゾルを含むスラリーを用いて担体基
材表面にコートし焼成して互いに固溶したセリウム酸化
物及びジルコニウム酸化物よりなり平均粒径が５〜１０
０ｎｍである固溶体を含むコート層を形成する工程と、
コート層に触媒貴金属を担持する工程と、を含んで構成
され、固溶体中のセリウム酸化物のジルコニウム酸化物
に対する固溶量はモル比で０．２〜４．０であることを
特徴とする。Further, in the method for producing an exhaust gas purifying catalyst of the fourth aspect of the present invention for producing the exhaust gas purifying catalyst of the second aspect of the present invention, a slurry containing a porous carrier powder and a cerium oxide sol and a zirconium oxide (zirconia) sol is used. It is composed of cerium oxide and zirconium oxide which are coated on the surface of a carrier substrate and baked to form a solid solution with each other, and have an average particle size of 5 to 10
Forming a coat layer containing a solid solution having a thickness of 0 nm;
And a step of supporting a catalytic noble metal on the coat layer, wherein the solid solution amount of the cerium oxide in the solid solution with respect to the zirconium oxide is 0.2 to 4.0 in molar ratio.
【００１０】また上記第２発明の排ガス浄化用触媒を製
造するもう一つの方法である第５発明の排ガス浄化用触
媒の製造方法は、多孔質担体粉末とセリウム酸化物ゾル
を含むスラリーを用いて担体基材表面にコートし焼成し
てコート層を形成する工程と、コート層にジルコニウム
化合物溶液を含浸させ焼成してコート層に互いに固溶し
たセリウム酸化物及びジルコニウム酸化物よりなり平均
粒径が５〜１００ｎｍである固溶体を形成する工程と、
コート層に触媒貴金属を担持する工程と、を含んで構成
され、固溶体中のセリウム酸化物のジルコニウム酸化物
に対する固溶量はモル比で０．２〜４．０であることを
特徴とする。The method for producing an exhaust gas purifying catalyst according to the fifth aspect of the present invention, which is another method for producing the exhaust gas purifying catalyst according to the second aspect of the present invention, uses a slurry containing a porous carrier powder and a cerium oxide sol. A step of forming a coat layer by coating on the surface of a carrier substrate and firing, and an average particle diameter consisting of cerium oxide and zirconium oxide solid-soluted in the coat layer by impregnating the coat layer with a zirconium compound solution and firing. Forming a solid solution having a thickness of 5 to 100 nm;
And a step of supporting a catalytic noble metal on the coat layer, wherein the solid solution amount of the cerium oxide in the solid solution with respect to the zirconium oxide is 0.2 to 4.0 in molar ratio.
【００１１】[0011]
【作用】セリアは酸素を一時的に貯蔵する機能をもち、
酸化雰囲気では酸素を貯蔵し、還元雰囲気では酸素を放
出する。これによりストイキ近傍における排ガスの雰囲
気変動が緩和され、その結果触媒性能が向上する。
（第１発明の作用）第１発明の排ガス浄化用触媒では、
多孔質担体に担持されたセリアの平均粒径は５〜１００
ｎｍであるので、粉末担持法に比べて十分小さく高分散
担持されている。したがって排ガスとの接触面積が十分
大きく、上記酸素貯蔵効果が十分発揮される。[Function] Ceria has a function of temporarily storing oxygen,
Oxygen is stored in the oxidizing atmosphere, and oxygen is released in the reducing atmosphere. As a result, fluctuations in the atmosphere of the exhaust gas in the vicinity of stoichiometry are alleviated, and as a result, catalyst performance improves. (Operation of First Invention) In the exhaust gas purifying catalyst of the first invention,
The average particle size of ceria supported on the porous carrier is 5 to 100.
Since it is nm, the particle size is sufficiently smaller than that in the powder carrying method, and highly dispersed and carried. Therefore, the contact area with the exhaust gas is sufficiently large, and the above oxygen storage effect is sufficiently exhibited.
【００１２】一方、セリアの平均粒径は多孔質担体の細
孔径（０．１〜５ｎｍ）に比べて比較的大きく、多孔質
担体との接触面積が小さい。したがってセリアが細孔を
閉塞したり、アルミネートを生成するような不具合が防
止されるので、セリアの酸素貯蔵効果と触媒活性の両方
が如何なく発揮され触媒性能が向上する。
（第２発明の作用）第２発明の排ガス浄化用触媒では、
セリアはジルコニアと固溶体を形成し、その固溶体の平
均粒径は５〜１００ｎｍである。したがって第１発明と
同様の作用が奏されるとともに、セリアより耐熱性の高
いジルコニアの固溶によりセリアのシンタリングが防止
され耐熱性が向上する。またジルコニアの固溶によりセ
リアとアルミナとの反応性も低下するので、アルミネー
トの生成が一層防止される。On the other hand, the average particle size of ceria is relatively larger than the pore size (0.1 to 5 nm) of the porous carrier, and the contact area with the porous carrier is small. Therefore, defects such as ceria blocking pores and forming aluminate are prevented, so that both the oxygen storage effect and the catalytic activity of ceria are exhibited and the catalytic performance is improved. (Operation of Second Invention) In the exhaust gas purifying catalyst of the second invention,
Ceria forms a solid solution with zirconia, and the average particle size of the solid solution is 5 to 100 nm. Therefore, the same effect as that of the first aspect of the invention is achieved, and sintering of ceria is prevented by the solid solution of zirconia having higher heat resistance than ceria, and heat resistance is improved. Further, the solid solution of zirconia reduces the reactivity between ceria and alumina, so that the formation of aluminate is further prevented.
【００１３】さらに、固溶体中のセリアのジルコニアに
対する固溶量は、モル比で０．２〜４．０である。この
範囲において耐熱性と酸素貯蔵効果の両方のバランスが
とれ、ジルコニアとセリアの両性能を最大に発揮するこ
とができる。
（第３発明の作用）第３発明の排ガス浄化用触媒の製造
方法では、セリアゾルを含むスラリーによりコート層が
形成される。セリアゾル中のセリアはコロイドであって
極めて粒径の小さな微粒子となっているので、スラリー
のコート後に焼成すれば、担持されたセリアの平均粒径
を容易に５〜１００ｎｍとすることができ、第１発明の
排ガス浄化用触媒を安定して容易に製造することができ
る。
（第４発明の作用）第４発明の排ガス浄化用触媒の製造
方法では、セリアゾルとジルコニアゾルを含むスラリー
によりコート層が形成される。両ゾル中のセリアとジル
コニアはコロイドであって極めて粒径の小さな微粒子と
なっているので、スラリーのコート後に焼成すれば、セ
リアとジルコニアは固溶体となりその平均粒径を容易に
５〜１００ｎｍとすることができる。したがって第２発
明の排ガス浄化用触媒を安定して容易に製造することが
できる。
（第５発明の作用）また第５発明の排ガス浄化用触媒の
製造方法では、先ずセリアゾルを含むスラリーによりコ
ート層が形成される。したがって第３発明と同様に、担
持されたセリアの平均粒径を容易に５〜１００ｎｍとす
ることができる。そして次にコート層にジルコニウム化
合物溶液を含浸させて焼成することにより、セリアとジ
ルコニアの固溶体が生成し、ジルコニアは高分散でセリ
アと接触するので固溶体の粒成長は僅かとなり、固溶体
の平均粒径を容易に５〜１００ｎｍとすることができ
る。したがって第２発明の排ガス浄化用触媒を安定して
容易に製造することができる。Further, the solid solution amount of ceria in zirconia in the solid solution is 0.2 to 4.0 in terms of molar ratio. In this range, both the heat resistance and the oxygen storage effect are balanced, and the performance of both zirconia and ceria can be maximized. (Operation of Third Invention) In the method for producing an exhaust gas-purifying catalyst of the third invention, the coat layer is formed of a slurry containing ceria sol. Since the ceria in the ceria sol is a colloid and is a fine particle having an extremely small particle size, the average particle size of the supported ceria can be easily set to 5 to 100 nm by firing after coating the slurry. The exhaust gas purifying catalyst of the invention can be stably and easily manufactured. (Operation of Fourth Invention) In the method for producing an exhaust gas purifying catalyst of the fourth invention, the coat layer is formed of a slurry containing ceria sol and zirconia sol. Since ceria and zirconia in both sols are colloids and are fine particles with an extremely small particle size, if ceria and zirconia are baked after coating the slurry, the ceria and zirconia will become a solid solution and the average particle size will easily be 5 to 100 nm. be able to. Therefore, the exhaust gas purifying catalyst of the second invention can be stably and easily manufactured. (Operation of Fifth Invention) In the method for producing an exhaust gas purifying catalyst according to the fifth invention, first, the coat layer is formed from a slurry containing ceria sol. Therefore, similarly to the third invention, the average particle size of the supported ceria can be easily set to 5 to 100 nm. Then, by impregnating the coating layer with the zirconium compound solution and baking, a solid solution of ceria and zirconia is generated, and since zirconia is in high dispersion and contacts with ceria, the grain growth of the solid solution becomes small, and the average particle diameter of the solid solution is small. Can be easily set to 5 to 100 nm. Therefore, the exhaust gas purifying catalyst of the second invention can be stably and easily manufactured.
【００１４】[0014]
〔発明の具体例〕多孔質担体の材質は特に限定されず、
アルミナ、シリカ、シリカ・アルミナ、チタニアなどか
ら選択して用いることができる。中でもアルミナが特に
好ましい。[Examples of the invention] The material of the porous carrier is not particularly limited,
Alumina, silica, silica-alumina, titania and the like can be selected and used. Of these, alumina is particularly preferable.
【００１５】セリア又はセリア、ジルコニアからなる固
溶体の平均粒径が５ｎｍより小さくなると、多孔質担体
に高分散に担持される反面、多孔質担体の細孔を閉塞し
たり、高温下においてセリアがアルミネートを生成して
触媒の比表面積を低下させたりする不具合が生じる。ま
た１００ｎｍより大きくなると、細孔の閉塞やアルミネ
ートの生成などは抑制されるものの、排ガスとの接触面
積が低下し浄化性能が低下する。When the average particle size of ceria or a solid solution composed of ceria and zirconia is smaller than 5 nm, the particles are supported in a highly dispersed state on the porous carrier, but on the other hand, the pores of the porous carrier are blocked or the ceria becomes aluminium at high temperature. There is a problem that nates are generated and the specific surface area of the catalyst is reduced. On the other hand, when it is larger than 100 nm, although the clogging of pores and the formation of aluminate are suppressed, the contact area with the exhaust gas is reduced and the purification performance is reduced.
【００１６】固溶体中のセリアのジルコニアに対する固
溶量がモル比で０．２未満であると、セリアの絶対量が
不足し酸素貯蔵効果が減少して触媒性能が低下する。ま
た４以上となると、ジルコニアの絶対量が不足し耐熱性
の向上効果が小さくなる。
〔実施例〕以下、実施例により具体的に説明する。
（実施例１・第３発明の製造方法と第１発明の排ガス浄
化用触媒）アルミナ粉末４７ｇと、ベーマイト（水酸化
アルミニウム）粉末１．５ｇと、セリアゾル（セリア含
有率３０重量％・セリアコロイドの平均粒径７ｎｍ））
７３ｇと水２５ｇを混合し、ボールミルで１時間ミリン
グした。その後硝酸アルミニウム１１．０ｇを混合し、
さらに３０分間ミリングしてスラリーを調製した。When the solid solution amount of ceria in the solid solution with respect to zirconia is less than 0.2 in molar ratio, the absolute amount of ceria is insufficient, the oxygen storage effect is reduced, and the catalytic performance is deteriorated. On the other hand, when it is 4 or more, the absolute amount of zirconia is insufficient and the effect of improving the heat resistance becomes small. [Examples] Hereinafter, specific examples will be described. (Example 1 ・ The manufacturing method of the third invention and the exhaust gas purifying catalyst of the first invention) 47 g of alumina powder, 1.5 g of boehmite (aluminum hydroxide) powder, and ceria sol (30% by weight ceria content of ceria colloid) Average particle size 7nm))
73 g and 25 g of water were mixed and milled with a ball mill for 1 hour. Then mix 11.0 g of aluminum nitrate,
The slurry was prepared by milling for another 30 minutes.
【００１７】次に直径３０ｍｍ×長さ２５ｍｍのコージ
ェライト製ハニカム担体基材を上記スラリーに浸漬し、
余分なスラリーを吹き払った後、８０℃で２０分間乾燥
し６５０℃で１時間焼成して、ハニカム担体基材表面に
コート層を形成した。コート層による重量増は３．０ｇ
である。この状態で走査電子顕微鏡にて観察したとこ
ろ、担持されたセリアの平均粒径は３５ｎｍであった。Next, a cordierite honeycomb carrier substrate having a diameter of 30 mm and a length of 25 mm is dipped in the above slurry,
After the excess slurry was blown off, it was dried at 80 ° C. for 20 minutes and fired at 650 ° C. for 1 hour to form a coat layer on the honeycomb carrier substrate surface. Weight increase due to coat layer is 3.0g
Is. When observed with a scanning electron microscope in this state, the average particle size of the supported ceria was 35 nm.
【００１８】コート層をもつ担体基材を所定濃度の白金
水溶液（「Ｐ−ソルト溶液」田中貴金属（株）製）中に
浸漬し、引き上げて余分な液滴を吹き払って２５０℃で
乾燥後、所定濃度の塩化ロジウム水溶液中に浸漬し、引
き上げて余分な液滴を吹き払って、２５０℃で乾燥し、
実施例１の排ガス浄化用触媒を得た。得られた排ガス浄
化用触媒では、Ｐｔが０．０２６５ｇ担持され、Ｒｈが
０．００５３ｇ担持されている。
（実施例２・第４発明の製造方法と第２発明の排ガス浄
化用触媒）アルミナ粉末４７ｇと、ベーマイト粉末１．
５ｇと、実施例１と同様のセリアゾル７３ｇと、ジルコ
ニアを３０重量％含有するジルコニアゾル（ジルコニア
コロイドの平均粒径３０ｎｍ）１０．３ｇ及び水１８ｇ
を混合し、ボールミルで１時間ミリングした。その後硝
酸アルミニウム１１．０ｇを混合し、さらに３０分間ミ
リングしてスラリーを調製した。The carrier substrate having a coat layer was dipped in an aqueous platinum solution ("P-salt solution" manufactured by Tanaka Kikinzoku Co., Ltd.) having a predetermined concentration, pulled up, blown off excess droplets, and dried at 250 ° C. , Soaked in a rhodium chloride aqueous solution of a predetermined concentration, pulled up to blow off excess droplets, and dried at 250 ° C.
The exhaust gas-purifying catalyst of Example 1 was obtained. In the obtained exhaust gas-purifying catalyst, 0.0265 g of Pt was loaded and 0.0053 g of Rh was loaded. (Example 2 and the manufacturing method of the fourth invention and the exhaust gas purifying catalyst of the second invention) 47 g of alumina powder and boehmite powder 1.
5 g, 73 g of the same ceria sol as in Example 1, 10.3 g of zirconia sol containing 30% by weight of zirconia (average particle size of zirconia colloid 30 nm), and 18 g of water
Were mixed and milled with a ball mill for 1 hour. Then, 11.0 g of aluminum nitrate was mixed and milled for 30 minutes to prepare a slurry.
【００１９】次に直径３０ｎｍ、長さ２５ｍｍのコージ
ェライト製ハニカム担体基材を上記スラリーに浸漬し、
余分なスラリーを吹き払った後、８０℃で２０分間乾燥
し７５０℃で１時間焼成して、ハニカム担体基材表面に
コート層を形成した。コート層による重量増は３．１０
ｇである。この状態でＸ線回折法により結晶構造を測定
したところ、セリアとジルコニアは互いに固溶して固溶
体を形成していることが確認された。また走査電子顕微
鏡にて観察したところ、セリアとジルコニアの固溶体の
平均粒径は６０ｎｍであった。Next, a cordierite honeycomb carrier substrate having a diameter of 30 nm and a length of 25 mm is dipped in the above slurry,
After blowing off the excess slurry, it was dried at 80 ° C. for 20 minutes and fired at 750 ° C. for 1 hour to form a coat layer on the surface of the honeycomb carrier substrate. Weight increase due to coat layer is 3.10.
It is g. When the crystal structure was measured by an X-ray diffraction method in this state, it was confirmed that ceria and zirconia solid-solved with each other to form a solid solution. When observed with a scanning electron microscope, the average particle size of the solid solution of ceria and zirconia was 60 nm.
【００２０】そして実施例１と同様にして、ＰｔとＲｈ
を同量担持し実施例２の排ガス浄化用触媒を得た。
（実施例３・第５発明の製造方法と第２発明の排ガス浄
化用触媒）実施例１で作製したものと同様のコート層を
もつハニカム担体基材に、濃度８．５重量％の硝酸ジル
コニル水溶液を含浸させ、乾燥後７５０℃で１時間焼成
した。これによる重量増は０．１５ｇであり、コート層
と合わせたハニカム担体基材の重量増は３．１５ｇであ
る。Then, in the same manner as in Example 1, Pt and Rh
Was carried in the same amount to obtain an exhaust gas purifying catalyst of Example 2. (Example 3; Production method of the fifth invention and exhaust gas purifying catalyst of the second invention) A honeycomb carrier substrate having a coat layer similar to that produced in Example 1 was used, and zirconyl nitrate having a concentration of 8.5% by weight was used. It was impregnated with an aqueous solution, dried and calcined at 750 ° C. for 1 hour. The resulting weight gain is 0.15 g and the honeycomb carrier substrate combined with the coat layer has a weight gain of 3.15 g.
【００２１】この状態でＸ線回折法により結晶構造を測
定したところ、セリアとジルコニアは互いに固溶して固
溶体を形成していることが確認された。また走査電子顕
微鏡にて観察したところ、セリアとジルコニアの固溶体
の平均粒径は３５ｎｍであった。そして実施例１と同様
にして、ＰｔとＲｈを同量担持し実施例３の排ガス浄化
用触媒を得た。
（比較例１、比較例２・含浸担持法）アルミナ粉末４７
ｇと、ベーマイト粉末１．５ｇと、水７０ｇ及び硝酸ア
ルミニウム１１．０ｇを混合し、ボールミルで１時間ミ
リングしてスラリーを調製した。When the crystal structure was measured by an X-ray diffraction method in this state, it was confirmed that ceria and zirconia solid-solved with each other to form a solid solution. When observed with a scanning electron microscope, the average particle size of the solid solution of ceria and zirconia was 35 nm. Then, in the same manner as in Example 1, the same amount of Pt and Rh were carried to obtain an exhaust gas purifying catalyst of Example 3. (Comparative Example 1 and Comparative Example 2 • Impregnation and Support Method) Alumina powder 47
g, 1.5 g of boehmite powder, 70 g of water and 11.0 g of aluminum nitrate were mixed, and milled for 1 hour with a ball mill to prepare a slurry.
【００２２】次に直径３０ｍｍ、長さ２５ｍｍのコージ
ェライト製ハニカム担体基材を２個準備し、これらを上
記スラリーに浸漬し、余分なスラリーを吹き払った後、
８０℃で２０分間乾燥し６５０℃で１時間焼成して、ハ
ニカム担体基材表面にコート層を形成した。コート層に
よる重量増は各々２．２５ｇおよび２．２０ｇである。Next, two cordierite honeycomb carrier base materials having a diameter of 30 mm and a length of 25 mm are prepared, these are immersed in the above slurry, and the excess slurry is blown off.
It was dried at 80 ° C. for 20 minutes and baked at 650 ° C. for 1 hour to form a coat layer on the surface of the honeycomb carrier substrate. The weight gain due to the coat layer is 2.25 g and 2.20 g, respectively.
【００２３】このコート層をもつ一方の担体基材に、８
０重量％の硝酸セリウム水溶液、あるいは７０重量％の
硝酸セリウムと８．５重量％の硝酸ジルコニルを含む混
合水溶液を含浸させ、乾燥後７５０℃で１時間焼成し
た。これまでのハニカム担体基材の重量増は各々３．２
５ｇおよび３．２０ｇである。そして実施例１と同様に
して、ＰｔとＲｈを同量担持し比較例１および比較例２
の排ガス浄化用触媒を得た。
（比較例３、比較例４・粉末担持法）セリア粉末２５ｇ
あるいは予めジルコニアを１２．５重量％固溶させたセ
リア−ジルコニア固溶体粉末２５ｇと、アルミナ粉末４
７ｇと、ベーマイト粉末１．５ｇと、硝酸アルミニウム
１１．０ｇ及び水８５ｇを混合し、ボールミルで１時間
ミリングしてスラリーを調製した。On one carrier substrate having this coating layer, 8
A 0% by weight aqueous cerium nitrate solution or a mixed aqueous solution containing 70% by weight cerium nitrate and 8.5% by weight zirconyl nitrate was impregnated, dried and calcined at 750 ° C. for 1 hour. Up to now, the weight increase of the honeycomb carrier base material is 3.2 each.
5 g and 3.20 g. Then, in the same manner as in Example 1, Pt and Rh were carried in the same amount, and Comparative Example 1 and Comparative Example 2
A catalyst for purification of exhaust gas was obtained. (Comparative Examples 3 and 4 Powder supporting method) Ceria powder 25 g
Alternatively, 25 g of ceria-zirconia solid solution powder in which 12.5% by weight of zirconia was previously solid-dissolved, and alumina powder 4
7 g, 1.5 g of boehmite powder, 11.0 g of aluminum nitrate and 85 g of water were mixed and milled with a ball mill for 1 hour to prepare a slurry.
【００２４】次に直径３０ｍｍ、長さ２５ｍｍのコージ
ェライト製ハニカム担体基材を２個準備し、これらを上
記スラリーに浸漬し、余分なスラリーを吹き払った後、
８０℃で２０分間乾燥し６５０℃で１時間焼成して、ハ
ニカム担体基材表面にコート層を形成した。コート層に
よる重量増は各々３．１０ｇおよび３．１５ｇである。Next, two cordierite honeycomb carrier base materials having a diameter of 30 mm and a length of 25 mm are prepared, these are immersed in the above slurry, and the excess slurry is blown off,
It was dried at 80 ° C. for 20 minutes and baked at 650 ° C. for 1 hour to form a coat layer on the surface of the honeycomb carrier substrate. The weight gain due to the coat layer is 3.10 g and 3.15 g, respectively.
【００２５】そして実施例１と同様にして、ＰｔとＲｈ
を同量担持し比較例３および比較例４の排ガス浄化用触
媒を得た。
（性能評価１）上記のそれぞれの排ガス浄化用触媒は、
表１に示す還元性ガスと酸化性ガスを５分毎に交互に流
す耐久試験に供された。入りガス温度は１０００℃であ
り、試験時間は１５時間である。耐久試験前および後の
排ガス浄化用触媒の比表面積と、初期のセリア又はセリ
ア−ジルコニア固溶体の平均粒径を測定した。結果を表
２に示す。Then, in the same manner as in Example 1, Pt and Rh
Were carried in the same amount to obtain exhaust gas purifying catalysts of Comparative Example 3 and Comparative Example 4. (Performance Evaluation 1) Each of the above exhaust gas purifying catalysts
It was subjected to a durability test in which a reducing gas and an oxidizing gas shown in Table 1 were alternately flowed every 5 minutes. The incoming gas temperature is 1000 ° C. and the test time is 15 hours. The specific surface area of the exhaust gas-purifying catalyst before and after the durability test and the average particle size of the initial ceria or ceria-zirconia solid solution were measured. The results are shown in Table 2.
【００２６】[0026]
【表１】 [Table 1]
【００２７】[0027]
【表２】
比較例１および比較例２では、他に比べて初期の比表面
積が小さく、また平均粒径も極めて小さい（測定不可）
ことから、高分散担持によりアルミナの細孔が閉塞され
ていると推定される。そして、耐久後の比表面積の低下
度合いが、比較例１は実施例１および比較例３に比べ
て、比較例２は実施例２、３および比較例４に比べて大
きいが、これはアルミナとセリアとの反応が生じたため
と推察される。[Table 2] In Comparative Example 1 and Comparative Example 2, the initial specific surface area is smaller than the others and the average particle size is also extremely small (not measurable).
Therefore, it is presumed that the pores of alumina are blocked by the highly dispersed support. The degree of decrease in the specific surface area after the endurance is larger in Comparative Example 1 than in Examples 1 and 3, and in Comparative Example 2 as compared with Examples 2, 3 and 4, which is different from that of alumina. It is speculated that a reaction with ceria occurred.
【００２８】また比較例３および４では比表面積は実施
例と同等であるものの、平均粒径が極めて大きいので、
セリアの酸素貯蔵効果が小さくなることが予測される。
一方、実施例では平均粒径が小さいにもかかわらず、大
きな比表面積を有している。また、耐久後の比表面積の
低下度合いも実施例１は比較例３と、実施例２および３
は比較例４と同等となっている。したがって、酸素貯蔵
効果の高い優れた三元活性を示す排気浄化用触媒が得ら
れることが予測される。In Comparative Examples 3 and 4, although the specific surface area is the same as that of the example, the average particle size is extremely large,
It is expected that the oxygen storage effect of ceria will decrease.
On the other hand, in the examples, although the average particle size is small, it has a large specific surface area. Further, the degree of decrease in specific surface area after endurance was the same as Example 1 in Comparative Example 3 and Examples 2 and 3.
Is equivalent to Comparative Example 4. Therefore, it is predicted that an exhaust gas purification catalyst having a high oxygen storage effect and excellent ternary activity can be obtained.
【００２９】また、各触媒ともジルコニアを固溶させる
ことで、耐久後の比表面積の低下を抑制することができ
ることがわかる。これはセリアにジルコニアを固溶させ
ることで、セリアの耐熱性が向上したために、担体であ
るアルミナとの反応が起こり難くなったことによるもの
と推察される。したがって、高温下で使用しても三元活
性の低下の小さい排ガス浄化用触媒が得られることが予
測される。Further, it is understood that the solid surface solution of zirconia in each catalyst can suppress the decrease in the specific surface area after the endurance. It is speculated that this is because the solid solution of zirconia in ceria improved the heat resistance of ceria, which made it difficult for the reaction with alumina as a carrier to occur. Therefore, it is expected that an exhaust gas-purifying catalyst with a small decrease in three-way activity can be obtained even when used at high temperatures.
【００３０】また、実施例２および実施例３より、ジル
コニアの効果は添加方法には影響されないことがわか
る。
（性能評価２）そこで、それぞれの排ガス浄化用触媒に
ついて昇温測定による触媒活性評価を行った。Further, it can be seen from Examples 2 and 3 that the effect of zirconia is not influenced by the addition method. (Performance Evaluation 2) Therefore, the catalyst activity was evaluated by measuring the temperature rise of each exhaust gas purifying catalyst.
【００３１】表３に示す還元性ガスと酸化性ガスを１秒
毎に交互に流し、入ガス温度を常温から５００℃まで昇
温させてＮＯｘ、ＣＯおよびＨＣの浄化特性を測定し
た。その結果からセリアの酸素貯蔵・放出効果が現れる
３５０℃におけるＮＯｘ、ＣＯ及びＨＣの浄化率を求め
比較した。結果を表４に示す。The reducing gas and the oxidizing gas shown in Table 3 were alternately flowed every one second, the temperature of the incoming gas was raised from room temperature to 500 ° C., and the purification characteristics of NOx, CO and HC were measured. From the results, the purification rates of NOx, CO, and HC at 350 ° C, where the oxygen storage / release effect of ceria appears, were obtained and compared. The results are shown in Table 4.
【００３２】[0032]
【表３】 (Co+H2 混合ガスの割合は、Co+H2 ≒3)[Table 3] (The ratio of Co + H 2 mixed gas is Co + H 2 ≈3)
【００３３】[0033]
【表４】
実施例１の排ガス浄化用触媒は比較例１および３に比べ
てＮＯｘおよびＣＯの浄化率が向上している。これは実
施例１の排ガス浄化用触媒ではセリアをゾルとして添加
したため、セリアの分散性が高く、酸素の貯蔵・放出能
力が向上したことを示している。一方、比較例１および
３の活性が悪くなった原因は、比較例１ではアルミナと
セリアの反応による比表面積の低下、比較例３はセリア
粒径が大きいために酸素の貯蔵・放出効果が十分発揮で
きなかったためと考えられる。[Table 4] The exhaust gas purifying catalyst of Example 1 has an improved purification rate of NOx and CO as compared with Comparative Examples 1 and 3. This indicates that since ceria was added as a sol in the exhaust gas purifying catalyst of Example 1, the dispersibility of ceria was high and the oxygen storage / release capacity was improved. On the other hand, the reason why the activity of Comparative Examples 1 and 3 deteriorated is that the specific surface area is decreased in Comparative Example 1 due to the reaction between alumina and ceria, and Comparative Example 3 has a large ceria particle size, so that the effect of storing and releasing oxygen is sufficient. It is considered that it was not possible to demonstrate it.
【００３４】また、実施例２および３の排ガス浄化用触
媒は同様の活性を示し、実施例１に比較して著しく活性
が向上した。さらに比較例２および４と比較してもＮＯ
ｘおよびＣＯの浄化率が向上している。これはジルコニ
アを固溶させることで、セリアの耐熱性が向上し、耐久
による酸素の貯蔵・放出効果の低下とアルミナ比表面積
の低下度合いを小さくしたためであることは明らかであ
る。Further, the exhaust gas-purifying catalysts of Examples 2 and 3 exhibited the same activity, and the activity was remarkably improved as compared with Example 1. Furthermore, even if compared with Comparative Examples 2 and 4, NO
The purification rates of x and CO are improved. It is apparent that this is because the solid solution of zirconia improves the heat resistance of ceria and reduces the effect of oxygen storage / release due to durability and the degree of decrease of the specific surface area of alumina.
【００３５】[0035]
【発明の効果】すなわち第１発明の排ガス浄化用触媒に
よれば、セリアの酸素貯蔵・放出効果が向上し、かつ細
孔の閉塞によるアルミナの比表面積の低下が防止されて
いるので、酸化雰囲気と還元雰囲気をくり返す変動条件
においても高い三元活性を有する。According to the exhaust gas purifying catalyst of the first aspect of the invention, the oxygen storage / release effect of ceria is improved, and the reduction of the specific surface area of alumina due to the clogging of pores is prevented. It has high ternary activity even under varying conditions where the reducing atmosphere is repeated.
【００３６】また第２発明の排ガス浄化用触媒によれ
ば、耐熱性の高い排ガス浄化用触媒を提供することがで
きる。また第３発明の排ガス浄化用触媒の製造方法によ
れば、セリアが小さな平均粒径で高分散担持された第１
発明の排ガス浄化用触媒を、容易にかつ安定して製造す
ることができる。Further, according to the exhaust gas purifying catalyst of the second invention, it is possible to provide an exhaust gas purifying catalyst having high heat resistance. Further, according to the method for producing an exhaust gas-purifying catalyst of the third invention, the first embodiment in which ceria is carried in a highly dispersed manner with a small average particle size
The exhaust gas-purifying catalyst of the present invention can be easily and stably produced.
【００３７】さらに、第４発明および第５発明の排ガス
浄化用触媒の製造方法によれば、セリアが小さな平均粒
径で高分散担持され、かつ、高温時にも比表面積の低下
を少なくした耐熱性の高い第２発明の排ガス浄化用触媒
を、容易にかつ安定して製造することができる。Furthermore, according to the method for producing an exhaust gas purifying catalyst of the fourth and fifth inventions, the ceria is highly dispersed and supported with a small average particle size, and the heat resistance is such that the reduction of the specific surface area is suppressed even at high temperature. Thus, the exhaust gas-purifying catalyst of the second invention having a high temperature can be easily and stably manufactured.
フロントページの続き (72)発明者 福井 雅幸 愛知県愛知郡長久手町大字長湫字横道41 番地の１ 株式会社豊田中央研究所内 (56)参考文献 特開 昭63−137753（ＪＰ，Ａ) 特開 昭63−116741（ＪＰ，Ａ) 特開 平８−141395（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B01J 21/00 - 38/74 B01D 53/94 Front page continuation (72) Masayuki Fukui Inventor Masayuki Fukui 1-41 Yokomichi Nagakute-cho, Aichi-gun, Aichi-gun Toyota Central Research Institute Co., Ltd. (56) Reference JP 63-137753 (JP, A) JP Sho 63-116741 (JP, A) JP-A-8-141395 (JP, A) (58) Fields investigated (Int.Cl. 7 , DB name) B01J 21/00 -38/74 B01D 53/94
Claims (5)
セリウム酸化物と、 該多孔質担体に担持されパラジウムを除く触媒貴金属
と、からなることを特徴とする排ガス浄化用触媒。Features and 1. A porous support, and an average particle diameter that is supported on the porous carrier cerium oxide of 5 to 100 nm, and catalytic noble metal other than palladium supported on porous support, in that it consists of Exhaust gas purification catalyst.
及びジルコニウム酸化物よりなり平均粒径が５〜１００
ｎｍである固溶体と、 該多孔質担体に担持された触媒貴金属とを含んで構成さ
れ、前記固溶体中のセリウム酸化物のジルコニウム酸化
物に対する固溶量はモル比で０．２〜４．０であること
を特徴とする排ガス浄化用触媒。2. An average particle diameter of 5 to 100, which comprises a porous carrier and cerium oxide and zirconium oxide supported on the porous carrier and solid-solved with each other.
nm and a catalytic noble metal supported on the porous carrier, and the solid solution amount of cerium oxide to zirconium oxide in the solid solution is 0.2 to 4.0 at a molar ratio. An exhaust gas purifying catalyst characterized by being present.
含むスラリーを用いて担体基材表面にコートし焼成して
平均粒径が５〜１００ｎｍのセリウム酸化物を含むコー
ト層を形成する工程と、 該コート層に触媒貴金属を担持する工程と、を含んで構
成されることを特徴とする排ガス浄化用触媒の製造方
法。3. A step of forming a coat layer containing cerium oxide having an average particle diameter of 5 to 100 nm by coating the surface of the carrier substrate with a slurry containing a porous carrier powder and a cerium oxide sol and baking the slurry. And a step of supporting a catalyst noble metal on the coat layer, the method for producing an exhaust gas-purifying catalyst.
びジルコニウム酸化物ゾルを含むスラリーを用いて担体
基材表面にコートし焼成して互いに固溶したセリウム酸
化物及びジルコニウム酸化物よりなり平均粒径が５〜１
００ｎｍである固溶体を含むコート層を形成する工程
と、 該コート層に触媒貴金属を担持する工程と、を含んで構
成され、 前記固溶体中のセリウム酸化物のジルコニウム酸化物に
対する固溶量はモル比で０．２〜４．０であることを特
徴とする排ガス浄化用触媒の製造方法。4. An average particle composed of cerium oxide and zirconium oxide which are solid-solved by coating the surface of a carrier substrate with a slurry containing a porous carrier powder and a cerium oxide sol and a zirconium oxide sol and firing the slurry. Diameter 5 to 1
The step of forming a coat layer containing a solid solution having a thickness of 00 nm and the step of supporting a catalytic noble metal on the coat layer are included, and the solid solution amount of cerium oxide to zirconium oxide in the solid solution is a molar ratio. In the range of 0.2 to 4.0.
含むスラリーを用いて担体基材表面にコートし焼成して
コート層を形成する工程と、 該コート層にジルコニウム化合物溶液を含浸させ焼成し
て該コート層に互いに固溶したセリウム酸化物及びジル
コニウム酸化物よりなり平均粒径が５〜１００ｎｍであ
る固溶体を形成する工程と、 該コート層に触媒貴金属を担持する工程と、を含んで構
成され、 前記固溶体中のセリウム酸化物のジルコニウム酸化物に
対する固溶量はモル比で０．２〜４．０であることを特
徴とする排ガス浄化用触媒の製造方法。5. A step of coating the surface of a carrier substrate with a slurry containing a porous carrier powder and a cerium oxide sol to form a coat layer by firing, and impregnating the coat layer with a zirconium compound solution and firing the solution. And a step of forming a solid solution of cerium oxide and zirconium oxide which are solid-solved with each other in the coating layer and having an average particle diameter of 5 to 100 nm, and a step of supporting a catalytic noble metal on the coating layer. The solid solution amount of cerium oxide in the solid solution with respect to zirconium oxide is 0.2 to 4.0 in molar ratio.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30626594A JP3362532B2 (en) | 1994-12-09 | 1994-12-09 | Exhaust gas purification catalyst and method for producing the same |
| EP95119403A EP0715879A1 (en) | 1994-12-09 | 1995-12-08 | Catalyst for purifying exhaust gases and process for producing the same |
| US08/569,396 US5945369A (en) | 1994-12-09 | 1995-12-08 | Catalyst for purifying exhaust gases and process for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30626594A JP3362532B2 (en) | 1994-12-09 | 1994-12-09 | Exhaust gas purification catalyst and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08155302A JPH08155302A (en) | 1996-06-18 |
| JP3362532B2 true JP3362532B2 (en) | 2003-01-07 |
Family
ID=17955003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30626594A Expired - Fee Related JP3362532B2 (en) | 1994-12-09 | 1994-12-09 | Exhaust gas purification catalyst and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3362532B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19714707A1 (en) * | 1997-04-09 | 1998-10-15 | Degussa | Oxygen-storing material with high temperature stability and process for its production |
| EP1423196B1 (en) * | 2001-09-14 | 2006-07-12 | Rothmans, Benson & Hedges Inc. | A process for making rare earth metal oxide-coated microporous materials |
| EP1433745A2 (en) | 2002-12-26 | 2004-06-30 | Matsushita Electric Industrial Co., Ltd. | Catalyst for the removal of carbon monoxide, its method of manufacture and its uses |
| JP5492448B2 (en) | 2009-04-28 | 2014-05-14 | 株式会社キャタラー | Exhaust gas purification catalyst |
| US8796171B2 (en) * | 2011-01-13 | 2014-08-05 | N.E. Chemcat Corporation | Denitration catalyst composition and method of denitration using same |
| JP6350142B2 (en) * | 2014-09-08 | 2018-07-04 | 株式会社デンソー | Honeycomb structure and manufacturing method thereof |
-
1994
- 1994-12-09 JP JP30626594A patent/JP3362532B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08155302A (en) | 1996-06-18 |
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