JP3265534B2 - Exhaust gas purification catalyst - Google Patents
Exhaust gas purification catalystInfo
- Publication number
- JP3265534B2 JP3265534B2 JP2000008589A JP2000008589A JP3265534B2 JP 3265534 B2 JP3265534 B2 JP 3265534B2 JP 2000008589 A JP2000008589 A JP 2000008589A JP 2000008589 A JP2000008589 A JP 2000008589A JP 3265534 B2 JP3265534 B2 JP 3265534B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- exhaust gas
- composite oxide
- carrier
- oxide
- 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 94
- 238000000746 purification Methods 0.000 title description 31
- 239000002131 composite material Substances 0.000 claims description 92
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 78
- 239000000843 powder Substances 0.000 claims description 74
- 239000002245 particle Substances 0.000 claims description 49
- 239000011812 mixed powder Substances 0.000 claims description 37
- 239000006104 solid solution Substances 0.000 claims description 34
- 229910000510 noble metal Inorganic materials 0.000 claims description 25
- 239000007787 solid Substances 0.000 claims description 16
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 14
- 229910021193 La 2 O 3 Inorganic materials 0.000 claims description 7
- 229910052697 platinum Inorganic materials 0.000 claims description 6
- 229910052703 rhodium Inorganic materials 0.000 claims description 6
- 238000002441 X-ray diffraction Methods 0.000 claims description 4
- 238000001354 calcination Methods 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 55
- 238000012360 testing method Methods 0.000 description 25
- 239000010410 layer Substances 0.000 description 24
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 20
- 239000007864 aqueous solution Substances 0.000 description 18
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 16
- 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 16
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 16
- 230000000694 effects Effects 0.000 description 14
- 229910052760 oxygen Inorganic materials 0.000 description 14
- 229910052684 Cerium Inorganic materials 0.000 description 13
- 230000007423 decrease Effects 0.000 description 13
- 239000001301 oxygen Substances 0.000 description 13
- 239000010948 rhodium Substances 0.000 description 13
- 239000002002 slurry Substances 0.000 description 13
- 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 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 12
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 12
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 11
- 239000000203 mixture Substances 0.000 description 11
- 229910052726 zirconium Inorganic materials 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 239000000758 substrate Substances 0.000 description 10
- 238000010304 firing Methods 0.000 description 9
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 8
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 8
- 229910001593 boehmite Inorganic materials 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 6
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 238000007664 blowing Methods 0.000 description 4
- 238000000975 co-precipitation Methods 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- 239000006185 dispersion Substances 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
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910052878 cordierite Inorganic materials 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 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 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 229910052746 lanthanum Inorganic materials 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 3
- 238000005191 phase separation Methods 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- XNDZQQSKSQTQQD-UHFFFAOYSA-N 3-methylcyclohex-2-en-1-ol Chemical compound CC1=CC(O)CCC1 XNDZQQSKSQTQQD-UHFFFAOYSA-N 0.000 description 2
- NGDQQLAVJWUYSF-UHFFFAOYSA-N 4-methyl-2-phenyl-1,3-thiazole-5-sulfonyl chloride Chemical compound S1C(S(Cl)(=O)=O)=C(C)N=C1C1=CC=CC=C1 NGDQQLAVJWUYSF-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001342 alkaline earth metals Chemical class 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical group [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 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 2
- 239000002184 metal Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- -1 oxygen ions Chemical class 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 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 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- IVORCBKUUYGUOL-UHFFFAOYSA-N 1-ethynyl-2,4-dimethoxybenzene Chemical compound COC1=CC=C(C#C)C(OC)=C1 IVORCBKUUYGUOL-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 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
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052792 caesium Inorganic materials 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- UNJPQTDTZAKTFK-UHFFFAOYSA-K cerium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Ce+3] UNJPQTDTZAKTFK-UHFFFAOYSA-K 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 150000004696 coordination complex Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052680 mordenite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- NWAHZABTSDUXMJ-UHFFFAOYSA-N platinum(2+);dinitrate Chemical compound [Pt+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O NWAHZABTSDUXMJ-UHFFFAOYSA-N 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 150000003754 zirconium Chemical class 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
- ATYZRBBOXUWECY-UHFFFAOYSA-N zirconium;hydrate Chemical compound O.[Zr] ATYZRBBOXUWECY-UHFFFAOYSA-N 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
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、自動車の排気系な
どに用いられる排ガス浄化用触媒に関し、詳しくはセリ
ア−ジルコニア複合酸化物を含み耐熱性が向上した排ガ
ス浄化用触媒に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying catalyst used for an exhaust system of an automobile, and more particularly to an exhaust gas purifying catalyst containing a ceria-zirconia composite oxide and having improved heat resistance.
【０００２】[0002]
【従来の技術】自動車の排気系に用いられている排ガス
浄化用触媒として、排ガス中のHC、CO及びNOx を同時に
浄化する三元触媒が広く用いられている。この三元触媒
は、アルミナ（ Al2O3）やシリカ（SiO2）などの多孔質
酸化物を担体とし、その担体に白金（Pt）やロジウム
（Rh）などの貴金属を担持した構成とされ、触媒に吸着
したHC及びCOを酸化して浄化するとともに、NOx を還元
して浄化している。2. Description of the Related Art As an exhaust gas purifying catalyst which is used in an exhaust system of an automobile, a three-way catalyst for purifying HC in exhaust gas, the CO and NO x simultaneously has been widely used. The three-way catalyst has a structure in which a porous oxide such as alumina (Al 2 O 3 ) or silica (SiO 2 ) is used as a carrier, and a noble metal such as platinum (Pt) or rhodium (Rh) is supported on the carrier. , together with purifying and oxidizing the adsorbed HC and CO in the catalyst, and purifying by reducing NO x.
【０００３】この三元触媒は、混合気の空燃比が理論空
燃比のストイキ雰囲気の排ガスと接触した場合に最も浄
化率が高くなるように設計されている。ところが現実の
空燃比は、自動車の走行条件によってストイキを中心に
してリッチ側あるいはリーン側に変動するため、排ガス
雰囲気も変動する。そのため、上記構成の三元触媒のみ
で必ずしも高い浄化性能が確保されるとは限らない。[0003] This three-way catalyst is designed to have the highest purification rate when it comes into contact with exhaust gas in a stoichiometric atmosphere having an air-fuel ratio of a stoichiometric air-fuel mixture. However, the actual air-fuel ratio fluctuates to a rich side or a lean side centering on stoichiometry depending on the driving conditions of the vehicle, so that the exhaust gas atmosphere also fluctuates. Therefore, high purification performance is not always ensured only by the three-way catalyst having the above configuration.
【０００４】そこで従来より、担体中にセリア（CeO2）
を含有させた三元触媒が知られている。セリアは酸素を
吸蔵放出する特性を有するため、リッチ雰囲気でセリア
に酸素が吸蔵されリーン雰囲気で酸素が放出される。し
たがってセリアを含有することで排ガスの雰囲気の変動
を緩和させることができ、浄化性能が向上する。またセ
リアにジルコニア（ZrO2）を複合化させたセリア−ジル
コニア複合酸化物を担体中に含有させることも好まし
い。ジルコニアを複合化することで、セリアの熱安定性
を大幅に向上させることができる。Therefore, conventionally, ceria (CeO 2 )
Is known. Since ceria has a property of storing and releasing oxygen, oxygen is stored in ceria in a rich atmosphere and released in a lean atmosphere. Therefore, by containing ceria, the fluctuation of the atmosphere of the exhaust gas can be reduced, and the purification performance is improved. It is also preferable to include a ceria-zirconia composite oxide in which zirconia (ZrO 2 ) is composited with ceria in the carrier. By combining zirconia, the thermal stability of ceria can be significantly improved.
【０００５】例えば特開平10−182155号公報には、セリ
ウム、ジルコニウム及びアルミニウムの少なくとも２種
を含む複合酸化物担体に貴金属を担持した排ガス浄化用
触媒が開示されている。[0005] For example, JP-A-10-182155 discloses an exhaust gas purifying catalyst in which a noble metal is supported on a composite oxide carrier containing at least two of cerium, zirconium and aluminum.
【０００６】[0006]
【発明が解決しようとする課題】ところで近年の高速走
行の増加などにより、自動車の排ガス温度はきわめて高
くなっている。そのため排ガス浄化用触媒の耐久試験の
条件もさらに厳しくする必要がある。However, due to the recent increase in high-speed running and the like, the exhaust gas temperature of automobiles has become extremely high. Therefore, the conditions for the durability test of the exhaust gas purifying catalyst also need to be stricter.
【０００７】ところが上記した従来の排ガス浄化用触媒
では、例えば1000℃で数時間加熱する程度の耐久試験で
はなんら不具合は発生しないが、1000℃で20時間程度加
熱する過酷な耐久試験を行うと、担体の組成によっては
セリアとジルコニアの固溶体に相分離が生じる場合があ
ることが明らかとなった。However, in the above-mentioned conventional exhaust gas purifying catalyst, no problem occurs in a durability test in which heating is performed at, for example, 1000 ° C. for several hours. However, when a severe durability test in which heating is performed at 1,000 ° C. for approximately 20 hours is performed, It became clear that phase separation may occur in the solid solution of ceria and zirconia depending on the composition of the carrier.
【０００８】また一般の排ガス浄化用触媒は、コージェ
ライトや金属箔から形成され耐熱性に優れたハニカム形
状の担体基材に、アルミナや複合酸化物などの担体粉末
からなるコート層を形成し、そのコート層に貴金属を担
持した構成とされている。ところが従来の特開平10−18
2155号公報に記載された複合酸化物担体からなるコート
層を形成した触媒に過酷な耐久試験を行うと、担体の熱
収縮によりコート層にひび割れが生じたり、コート層が
剥離したりする不具合が生じることがわかった。A general catalyst for purifying exhaust gas comprises forming a coat layer made of a carrier powder such as alumina or a composite oxide on a honeycomb-shaped carrier substrate made of cordierite or metal foil and having excellent heat resistance. The coat layer is configured to carry a noble metal. However, the conventional Japanese Patent Laid-Open No. 10-18
When a severe durability test is performed on a catalyst having a coat layer formed of a composite oxide carrier described in No. 2155, a crack occurs in the coat layer due to heat shrinkage of the carrier, or a problem such that the coat layer peels off. Was found to occur.
【０００９】本発明は、セリア−ジルコニア固溶体を含
む担体に貴金属が担持された排ガス浄化用触媒の耐熱性
を一層向上させ、過酷な耐久試験後にも高い浄化活性を
示すとともに、コート層のひび割れ及びクラックの発生
が防止された排ガス浄化用触媒とすることを目的とす
る。The present invention further improves the heat resistance of an exhaust gas purifying catalyst in which a noble metal is supported on a carrier containing a ceria-zirconia solid solution, exhibits a high purifying activity even after a severe durability test, and shows cracks in a coating layer and cracks. An object of the present invention is to provide an exhaust gas purifying catalyst in which cracks are prevented from being generated.
【００１０】[0010]
【課題を解決するための手段】上記課題を解決する請求
項１に記載の排ガス浄化用触媒の特徴は、多孔質酸化物
の粉末と式（１）で表される複合酸化物の粉末との混合
粉末よりなる担体と、該担体に担持された貴金属と、か
らなる排ガス浄化用触媒であって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （１） （式（１）においてａ及びｂはモル比を示し、ａは 0.4
〜 2.5、ｂは 0.2〜 0.7の範囲にある） 混合粉末には粒径５μｍ以上の粉末が30体積％以上含ま
れていることｂにある。According to a first aspect of the present invention, there is provided an exhaust gas purifying catalyst comprising a porous oxide powder and a composite oxide powder represented by the formula (1). An exhaust gas purifying catalyst comprising a carrier comprising a mixed powder and a noble metal carried on the carrier, wherein (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (1) In (1), a and b indicate a molar ratio, and a is 0.4
-2.5, b is in the range of 0.2-0.7) The mixed powder contains 30% by volume or more of powder having a particle size of 5 μm or more.
【００１１】請求項２に記載の排ガス浄化用触媒の特徴
は、多孔質酸化物の粉末と式（２）で表される複合酸化
物の粉末との混合粉末よりなる担体と、担体に担持され
た貴金属と、からなる排ガス浄化用触媒であって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （Y2O3）c （２） （式（２）においてａ、ｂ及びｃはモル比を示し、ａは
0.4〜 2.5、ｂは 0.2〜 0.7、ｃは0.01〜 0.2の範囲に
ある） 混合粉末には粒径５μｍ以上の粉末が30体積％以上含ま
れていることにある。According to a second aspect of the present invention, there is provided an exhaust gas purifying catalyst comprising: a carrier comprising a mixed powder of a porous oxide powder and a composite oxide powder represented by the formula (2); An exhaust gas purifying catalyst comprising: (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (Y 2 O 3 ) c (2) (in the formula (2), , B and c indicate the molar ratio, and a is
(0.4 to 2.5, b is in the range of 0.2 to 0.7, and c is in the range of 0.01 to 0.2) The mixed powder contains 30% by volume or more of powder having a particle size of 5 μm or more.
【００１２】請求項３に記載の排ガス浄化用触媒の特徴
は、多孔質酸化物の粉末と式（３）で表される複合酸化
物の粉末との混合粉末よりなる担体と、担体に担持され
た貴金属と、からなる排ガス浄化用触媒であって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （ La2O3）d （３） （式（３）においてａ、ｂ及びｄはモル比を示し、ａは
0.4〜 2.5、ｂは 0.2〜 0.7、ｄは 0.005〜 0.1の範囲
にある） 混合粉末には粒径５μｍ以上の粉末が30体積％以上含ま
れていることにある。According to a third aspect of the present invention, there is provided a catalyst for purifying exhaust gas, comprising: a carrier comprising a mixed powder of a powder of a porous oxide and a powder of a complex oxide represented by the formula (3); An exhaust gas purifying catalyst comprising: (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (La 2 O 3 ) d (3) (a in formula (3) , B and d indicate the molar ratio, and a is
(0.4 to 2.5, b is in the range of 0.2 to 0.7, and d is in the range of 0.005 to 0.1) The mixed powder contains 30% by volume or more of powder having a particle size of 5 µm or more.
【００１３】請求項４に記載の排ガス浄化用触媒の特徴
は、多孔質酸化物の粉末と式（４）で表される複合酸化
物の粉末との混合粉末よりなる担体と、担体に担持され
た貴金属と、からなる排ガス浄化用触媒であって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （Y2O3）c （ La2O3）d （４） （式（４）においてａ、ｂ、ｃ及びｄはモル比を示し、
ａは 0.4〜 2.5、ｂは0.2〜 0.7、ｃは0.01〜 0.2、ｄ
は 0.005〜 0.1の範囲にある） 混合粉末には粒径５μｍ以上の粉末が30体積％以上含ま
れていることにある。According to a fourth aspect of the present invention, there is provided an exhaust gas purifying catalyst comprising: a carrier comprising a mixed powder of a porous oxide powder and a composite oxide powder represented by the formula (4); An exhaust gas purifying catalyst comprising: (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1-b (Y 2 O 3 ) c (La 2 O 3 ) d (4) (In the formula (4), a, b, c and d indicate a molar ratio,
a is 0.4 to 2.5, b is 0.2 to 0.7, c is 0.01 to 0.2, d
Is in the range of 0.005 to 0.1) The mixed powder contains 30% by volume or more of powder having a particle size of 5 μm or more.
【００１４】また請求項５に記載の排ガス浄化用触媒の
特徴は、請求項１〜４のいずれかに記載の排ガス浄化用
触媒において、複合酸化物中のCeO2とZrO2は固溶体を形
成し、複合酸化物中のZrO2の固溶度が50％以上、より好
ましくは70％以上、さらに好ましくは80％以上であるこ
とにある。The exhaust gas purifying catalyst according to claim 5 is characterized in that, in the exhaust gas purifying catalyst according to any one of claims 1 to 4, CeO 2 and ZrO 2 in the composite oxide form a solid solution. The solid solubility of ZrO 2 in the composite oxide is 50% or more, more preferably 70% or more, and further preferably 80% or more.
【００１５】請求項６に記載の排ガス浄化用触媒の特徴
は、請求項１〜５のいずれかに記載の排ガス浄化用触媒
において、担体を1000℃で５時間焼成後の複合酸化物中
のセリア−ジルコニア固溶体の平均結晶子径がＸ線回折
による測定で10nm以下であることにある。According to a sixth aspect of the present invention, there is provided an exhaust gas purifying catalyst according to any one of the first to fifth aspects, wherein the carrier is calcined at 1000 ° C. for 5 hours in the composite oxide. The average crystallite diameter of the zirconia solid solution is 10 nm or less as measured by X-ray diffraction.
【００１６】請求項７に記載の排ガス浄化用触媒の特徴
は、請求項１〜６のいずれかに記載の排ガス浄化用触媒
において、担体中の多孔質酸化物と複合酸化物との重量
比が0.30≦複合酸化物／（複合酸化物＋多孔質酸化物）
≦ 0.7であることにある。A feature of the exhaust gas purifying catalyst according to claim 7 is that, in the exhaust gas purifying catalyst according to any one of claims 1 to 6, the weight ratio between the porous oxide and the composite oxide in the carrier is reduced. 0.30 ≦ composite oxide / (composite oxide + porous oxide)
≤ 0.7.
【００１７】請求項８に記載の排ガス浄化用触媒の特徴
は、請求項１〜７のいずれかに記載の排ガス浄化用触媒
において、複合酸化物にPdが担持され、担体にはさらに
Pt及びRhの少なくとも一方が担持されていることにあ
る。The exhaust gas purifying catalyst according to claim 8 is characterized in that, in the exhaust gas purifying catalyst according to any one of claims 1 to 7, Pd is supported on the composite oxide, and the carrier further comprises Pd.
That is, at least one of Pt and Rh is supported.
【００１８】また請求項９に記載の排ガス浄化用触媒の
特徴は、請求項１〜８のいずれかに記載の排ガス浄化用
触媒において、混合粉末には粒径５μｍ以上の粉末が85
体積％未満の割合で含まれていることにある。The exhaust gas purifying catalyst according to the ninth aspect is characterized in that, in the exhaust gas purifying catalyst according to any one of the first to eighth aspects, the mixed powder contains powder having a particle size of 5 μm or more.
That is, it is contained at a ratio of less than volume%.
【００１９】[0019]
【発明の実施の形態】本発明では、多孔質酸化物の粉末
と式（１）〜式（４）で表される複合酸化物の粉末との
混合粉末よりなる担体を用い、混合粉末には粒径５μｍ
以上の粉末が30体積％以上、好ましくは40体積％以上、
さらに好ましくは50体積％以上含まれている。このよう
に混合粉末に粒径５μｍ以上の粉末が30体積以上、好ま
しくは40体積％以上、さらに好ましくは50体積％以上含
まれた構成とすることで、1000℃で20時間程度加熱する
過酷な耐久試験を行っても、コート層にひび割れが生じ
たりコート層が剥離したりするような不具合が防止され
る。混合粉末において粒径が５μｍ以上の粉末が30体積
％未満では、耐久試験時の熱収縮が大きくなると考えら
れ、後述の実施例でも示すようにコート層にひび割れや
剥離が生じる。なお粒径とは、混合粉末よりなる担体の
粒径をいう。DETAILED DESCRIPTION OF THE INVENTION In the present invention, a carrier comprising a mixed powder of a porous oxide powder and a composite oxide powder represented by the formulas (1) to (4) is used. Particle size 5μm
The above powder is 30% by volume or more, preferably 40% by volume or more,
More preferably, the content is 50% by volume or more. As described above, the mixed powder contains powder having a particle size of 5 μm or more in an amount of 30% by volume or more, preferably 40% by volume or more, and more preferably 50% by volume or more. Even when a durability test is performed, problems such as cracking of the coat layer and peeling of the coat layer are prevented. If the powder having a particle diameter of 5 μm or more in the mixed powder is less than 30% by volume, the heat shrinkage during the durability test is considered to be large, and cracks and peeling occur in the coat layer as shown in Examples described later. The particle size refers to the particle size of the carrier made of the mixed powder.
【００２０】また複合酸化物の組成において、式（１）
〜式（４）のａの値が 0.4より小さいとセリア−ジルコ
ニア複合酸化物の高分散化を図ることが困難となり、過
酷な耐久試験後にセリア−ジルコニア複合酸化物の比表
面積が低下して浄化性能が低下する。またａの値が 2.5
を超えると、セリア−ジルコニア複合酸化物が量的に少
なくなって十分な酸素吸蔵放出能（以下、ＯＳＣとい
う）が確保できず、良好な浄化性能が得られない。なお
ａの値として好ましくは 0.4以上 2.0以下、さらに好ま
しくは 0.4以上 1.0以下、より好ましくは0.45以上 0.7
以下がよい。In the composition of the composite oxide, the formula (1)
When the value of a in the formula (4) is smaller than 0.4, it is difficult to achieve a high dispersion of the ceria-zirconia composite oxide, and the specific surface area of the ceria-zirconia composite oxide is reduced after a severe durability test to purify the oxide. Performance decreases. If the value of a is 2.5
If it exceeds 3, the ceria-zirconia composite oxide is reduced in quantity, so that sufficient oxygen storage / release capability (hereinafter referred to as OSC) cannot be secured, and good purification performance cannot be obtained. The value of a is preferably 0.4 or more and 2.0 or less, more preferably 0.4 or more and 1.0 or less, more preferably 0.45 or more and 0.7 or less.
The following is good.
【００２１】そして式（１）〜式（４）のｂの値が 0.2
より小さいとセリウム量が少なくて十分なＯＳＣが確保
できないために良好な浄化性能が得られず、ｂの値が
0.7を超えるとセリア−ジルコニア複合酸化物の熱安定
性が低下し過酷な耐久試験後の浄化性能が低下する。ｂ
の値としては 0.3以上 0.6以下の範囲とすることが好ま
しく、さらに 0.4以上 0.6以下の範囲が好ましい。The value of b in equations (1) to (4) is 0.2
If it is smaller, the cerium content is small and sufficient OSC cannot be secured, so that good purification performance cannot be obtained.
If it exceeds 0.7, the thermal stability of the ceria-zirconia composite oxide decreases, and the purification performance after a severe durability test decreases. b
Is preferably in the range of 0.3 or more and 0.6 or less, more preferably 0.4 or more and 0.6 or less.
【００２２】式（２）及び式（４）に示すように、複合
酸化物にさらにY2O3を添加することにより、セリア−ジ
ルコニア複合酸化物の1000℃以上の酸化雰囲気における
耐久性が一層向上し、セリア−ジルコニア複合酸化物の
相分離が生じにくくなるとともに、貴金属の活性が促進
される。式（２）及び式（４）のｃの値が0.01未満であ
るとY2O3を添加した効果が得られず、ｃの値が 0.2を超
えるとセリア−ジルコニア複合酸化物の耐熱性が低下す
るとともに貴金属の活性が低下する。As shown in the formulas (2) and (4), by further adding Y 2 O 3 to the composite oxide, the durability of the ceria-zirconia composite oxide in an oxidizing atmosphere at 1000 ° C. or higher is further improved. As a result, phase separation of the ceria-zirconia composite oxide hardly occurs, and the activity of the noble metal is promoted. When the value of c in the formulas (2) and (4) is less than 0.01, the effect of adding Y 2 O 3 cannot be obtained, and when the value of c exceeds 0.2, the heat resistance of the ceria-zirconia composite oxide is reduced. As the activity decreases, the activity of the noble metal decreases.
【００２３】また式（３）及び式（４）に示すように、
複合酸化物にさらに La2O3を添加することにより、セリ
ア−ジルコニア複合酸化物の1000℃以上の酸化雰囲気に
おける耐久性が一層向上し、過酷な耐久試験後にもセリ
ア−ジルコニア複合酸化物の比表面積が高く維持され
る。式（３）及び式（４）のｄの値が 0.005未満である
と La2O3を添加した効果が得られず、ｄの値が 0.1を超
えるとセリア−ジルコニア複合酸化物の耐熱性が低下す
る。なお式（２）〜（４）のY2O3及び La2O3の少なくと
も一方は、セリア−ジルコニア複合酸化物及びアルミナ
に固溶していることが好ましい。As shown in equations (3) and (4),
By further adding La 2 O 3 to the composite oxide, the durability of the ceria-zirconia composite oxide in an oxidizing atmosphere at 1000 ° C. or more is further improved, and the ratio of the ceria-zirconia composite oxide is maintained even after a severe durability test. The surface area is kept high. When the value of d in the formulas (3) and (4) is less than 0.005, the effect of adding La 2 O 3 is not obtained, and when the value of d exceeds 0.1, the heat resistance of the ceria-zirconia composite oxide is reduced. descend. Note that at least one of Y 2 O 3 and La 2 O 3 in the formulas (2) to (4) is preferably dissolved in a ceria-zirconia composite oxide and alumina.
【００２４】なお式（１）〜式（４）に示す複合酸化物
には、アルカリ金属、アルカリ土類金属、希土類元素及
び遷移金属元素から選ばれる添加元素をさらに微量含む
ことも好ましい。このような添加元素を含むことによ
り、セリア−ジルコニア複合酸化物の耐熱性が一層向上
する。この添加元素の添加量は、式（１）〜式（４）に
対して酸化物のモル比で0.05以下とすることが望まし
い。つまり添加元素Ｍを添加した場合、例えば式（２）
は（ Al2O3）a （CeO2）b （ZrO2）1-b（Y2O3)c （MO）
e と表され、モル比ｅの値は０〜0.05の範囲である。It is preferable that the complex oxide represented by the formulas (1) to (4) further contain a trace amount of an additional element selected from alkali metals, alkaline earth metals, rare earth elements and transition metal elements. By including such an additive element, the heat resistance of the ceria-zirconia composite oxide is further improved. It is desirable that the amount of the additional element be 0.05 or less in terms of the molar ratio of the oxide to the formulas (1) to (4). That is, when the additive element M is added, for example, the formula (2)
The (Al 2 O 3) a ( CeO 2) b (ZrO 2) 1-b (Y 2 O 3) c (MO)
is expressed as e, the molar ratio e is in the range of 0 to 0.05.
【００２５】アルカリ金属としてはNa、Ｋ、Li、Csが望
ましく、アルカリ土類金属としてはMg、Ca、Sr、Baが望
ましく、希土類元素としてLa、Pr、Nd、Pm、Sm、Eu、G
d、Tb、Dy、Ho、Er、Tm、Yb、Luから選ばれたものでも
よい。また遷移金属元素としては、Fe、Cu、Ni、Co、Mn
などが例示される。これらの一種でもよいし、二種以上
を併用することもできる。二種以上を併用した場合に
は、それらの合計量が原子比で0.05以下の範囲となるよ
うに添加する。As the alkali metal, Na, K, Li, and Cs are preferable, as the alkaline earth metal, Mg, Ca, Sr, and Ba are preferable. As the rare earth element, La, Pr, Nd, Pm, Sm, Eu, and G are used.
It may be selected from d, Tb, Dy, Ho, Er, Tm, Yb, and Lu. As transition metal elements, Fe, Cu, Ni, Co, Mn
And the like. One of these may be used, or two or more of them may be used in combination. When two or more kinds are used in combination, they are added so that the total amount thereof is in the range of 0.05 or less in atomic ratio.
【００２６】上記複合酸化物中の少なくともCeO2とZrO2
は固溶体を形成し、固溶体中のZrO2の固溶度が50％以
上、より好ましくは70％以上、さらに好ましくは80％以
上であることが望ましい。これによりセリア−ジルコニ
ア複合酸化物の1000℃以上の酸化雰囲気における耐久性
が一層向上し、セリア−ジルコニア複合酸化物の相分離
が一層生じにくくなる。At least CeO 2 and ZrO 2 in the above composite oxide
Forms a solid solution, and the solid solubility of ZrO 2 in the solid solution is preferably 50% or more, more preferably 70% or more, and further preferably 80% or more. As a result, the durability of the ceria-zirconia composite oxide in an oxidizing atmosphere at 1000 ° C. or higher is further improved, and phase separation of the ceria-zirconia composite oxide is less likely to occur.
【００２７】固溶度とは、次式（５）によって定義され
る値をいう。The solid solubility refers to a value defined by the following equation (5).
【００２８】 固溶度（％）＝ 100×（酸化物Ａの総量に固溶した酸化物Ｂの量）／酸化物Ｂ の総量・・・（５） ここで酸化物Ａの総量に固溶した酸化物Ｂは、酸化物Ａ
の総量に対して均一に固溶していると仮定する。Solid solubility (%) = 100 × (amount of oxide B dissolved in the total amount of oxide A) / total amount of oxide B (5) Here, solid solution in the total amount of oxide A Oxide B is converted to Oxide A
Is assumed to be uniformly dissolved with respect to the total amount of
【００２９】例えばセリアとジルコニアの固溶体の場合
は、セリアが酸化物Ａに、ジルコニアが酸化物Ｂに相当
し、固溶度（％）は、 100×（セリアの総量に固溶した
ジルコニアの量）／ジルコニアの総量、と表される。こ
こでセリア−ジルコニア固溶体（固溶度 100％）のジル
コニア濃度ｘ（mol%）と格子定数ｆ（Å）の間には、JC
PDSカードに示されている値より、次式（６）の関係が
ある。For example, in the case of a solid solution of ceria and zirconia, ceria corresponds to oxide A and zirconia corresponds to oxide B. The solid solubility (%) is 100 × (the amount of zirconia dissolved in the total amount of ceria). ) / Total amount of zirconia. Here, between the zirconia concentration x (mol%) of the ceria-zirconia solid solution (solid solubility 100%) and the lattice constant f (Å), JC
According to the value shown in the PDS card, the following equation (6) holds.
【００３０】 ｘ＝（ 5.411−ｆ）／ 0.00253・・・（６） また本発明にいう酸化物固溶体粒子では、固溶体粒子中
の結晶子の平均径が10nm以下である。この結晶子の大き
さは、Ｘ先回折ピークの半値幅より、次式のシェラーの
式を用いて算出される。X = (5.411−f) /0.00253 (6) In the oxide solid solution particles according to the present invention, the average diameter of crystallites in the solid solution particles is 10 nm or less. The size of this crystallite is calculated from the half value width of the diffraction peak at the X-point using the following Scherrer equation.
【００３１】Ｄ＝ｋλ／（β COSθ） ここでｋ：定数 0.9、λ：Ｘ線の波長（Å）、β：試料
の回折線幅−標準試料の回折線幅（ラジアン）、θ：回
折角（度） 結晶子の平均径が10nm以下であれば、結晶子が緻密な充
填になっておらず、結晶子間に細孔をもった固溶体粒子
となる。平均結晶子径が10nmを超えると、細孔容積及び
比表面積が低下し耐熱性も低下するようになる。この比
表面積は10m2／ｇ以上、さらには20m2／ｇ以上、より好
ましくは50m2／ｇ以上であることが望ましい。D = kλ / (β COSθ) where k: constant 0.9, λ: wavelength of X-ray (Å), β: diffraction line width of sample−diffraction line width of standard sample (radian), θ: diffraction angle (Degree) When the average diameter of the crystallites is 10 nm or less, the crystallites are not densely packed and are solid solution particles having pores between crystallites. When the average crystallite diameter exceeds 10 nm, the pore volume and the specific surface area decrease, and the heat resistance also decreases. The specific surface area 10 m 2 / g or more, further 20 m 2 / g or more, and more preferably at 50 m 2 / g or more.
【００３２】本発明にいう複合酸化物中では、セリアと
ジルコニアの固溶体は、酸化第２セリウムの蛍石構造を
保ったままセリウムの位置の一部をジルコニウムが置換
して固溶体となり、ジルコニアが十分固溶している。そ
の固溶体中では、ジルコニアの骨格が形成される。した
がって立方晶の結晶構造が安定となり、その固溶体が多
くの酸素を排出しても立方晶が維持される。その機構は
明らかではないが、立方晶の場合には酸素の移動が容易
となると考えられ、他の正方晶や単斜晶などに比べて高
いＯＳＣを示す。In the composite oxide according to the present invention, the solid solution of ceria and zirconia becomes a solid solution by substituting a part of the cerium position with zirconium while maintaining the fluorite structure of cerium oxide. Solid solution. A zirconia skeleton is formed in the solid solution. Therefore, the crystal structure of the cubic crystal becomes stable, and the cubic crystal is maintained even if the solid solution discharges a large amount of oxygen. Although the mechanism is not clear, the transfer of oxygen is considered to be easy in the case of the cubic system, and the OSC is higher than that of other tetragonal systems or monoclinic systems.
【００３３】また結晶子の平均径が10nm以下と小さいの
で、結晶子間の粒界が多くなり、粒界を移動する酸素イ
オンが移動しやすくなるため、酸素の吸蔵・放出速度が
十分大きくなり、酸素ストアレージ能が一層向上する。
そして比表面積が10m2／ｇ以上と大きければ、酸素の吸
蔵・放出は表面で行われるから、酸素の吸蔵・放出速度
が十分大きくなり、高いＯＳＣと相まって優れた酸素ス
トアレージ能を示す。Further, since the average diameter of the crystallites is as small as 10 nm or less, the number of grain boundaries between the crystallites increases, and oxygen ions moving through the grain boundaries easily move. The oxygen storage capacity is further improved.
If the specific surface area is as large as 10 m 2 / g or more, since oxygen is stored and released on the surface, the rate of storing and releasing oxygen is sufficiently high, and excellent oxygen storage capability is exhibited in combination with high OSC.
【００３４】複合酸化物は、各構成元素が固溶等でほぼ
均一な分散状態を保持する。複合酸化物を構成するセリ
ア−ジルコニアの結晶子径は５ｎｍ以下であることが好
ましい。さらに、該複合酸化物担体は、空気中1000℃で
５時間処理した後においてもセリア−ジルコニアの結晶
子径が10ｎｍ以下であるとともに、複合酸化物中に含ま
れるセリウムとジルコニウムの60％以上が30ｎｍ以下、
より好ましくは20ｎｍ以下、さらに好ましくは80％以上
が30ｎｍ以下、より好ましくは20ｎｍ以下、一層好まし
くは90％以上が30ｎｍ以下、より好ましくは20ｎｍ以
下、最も好ましくは10ｎｍ以下の粒子として分散してい
ることが望ましい。なお本発明の実施例における複合酸
化物では、60％以上が30ｎｍ以下の粒子として分散して
いることがＳＥＭ観察、ＴＥＭ観察及び元素分析の結果
から確認されている。The composite oxide maintains a substantially uniform dispersion state in which each constituent element is in a solid solution or the like. The crystallite diameter of ceria-zirconia constituting the composite oxide is preferably 5 nm or less. Further, the composite oxide carrier has a ceria-zirconia crystallite size of 10 nm or less even after being treated at 1000 ° C. for 5 hours in air, and 60% or more of cerium and zirconium contained in the composite oxide. 30 nm or less,
More preferably 20 nm or less, more preferably 80% or more is dispersed as 30 nm or less, more preferably 20 nm or less, still more preferably 90% or more is 30 nm or less, more preferably 20 nm or less, most preferably 10 nm or less. It is desirable. It is confirmed from the results of SEM observation, TEM observation, and elemental analysis that 60% or more of the composite oxide in Examples of the present invention is dispersed as particles having a size of 30 nm or less.
【００３５】この場合の結晶子径や粒子径の定義として
は、セリア−ジルコニア結晶子や粒子の間に介在してい
るアルミナ粒子又はアルミニウム原子の間隔を意味す
る。また、アルミナ粒子やアルミナ結晶子に、セリア−
ジルコニア結晶又は粒子又は原子が介在物として分散し
ている間隔であってもよい。複合酸化物中の結晶子径や
粒子径が30ｎｍより大きくなると、複合酸化物担体触媒
として有効に作用するセリア及び／又はジルコニアの割
合が低下し、貴金属の活性が低下したり、触媒としての
ＯＳＣが低下して変動雰囲気中での三元触媒のNOx 、H
C、COに対する浄化性能が低下するので好ましくない。
さらに、酸化セリウムと酸化ジルコニウムとの複合化
（固溶）が十分でない場合もＯＳＣと浄化性能が低くな
るので好ましくない。The definition of the crystallite diameter and the particle diameter in this case means the ceria-zirconia crystallite and the distance between alumina particles or aluminum atoms interposed between the particles. In addition, ceria is added to alumina particles and alumina crystallites.
The spacing may be such that zirconia crystals or particles or atoms are dispersed as inclusions. When the crystallite size or particle size in the composite oxide is larger than 30 nm, the ratio of ceria and / or zirconia effectively acting as a composite oxide carrier catalyst decreases, the activity of noble metals decreases, and the OSC as a catalyst decreases. NO x, H of the three-way catalyst in a variation atmosphere but decreases
It is not preferable because the purification performance for C and CO decreases.
Further, it is not preferable that the composite (solid solution) of cerium oxide and zirconium oxide is not sufficient because the OSC and purification performance are lowered.
【００３６】なお、セリアとジルコニアの固溶体の場合
は、セリウムとジルコニウムのモル比で、 0.3≦Zr／
（Ce＋Zr）≦ 0.8の範囲が好ましく、 0.4≦Zr／（Ce＋
Zr）≦0.6の範囲が特に好ましい。ジルコニウムの含有
率が30モル％以下になると、固溶体の結晶中でジルコニ
ウムの骨格を形成する作用が弱まり、酸素の脱離により
蛍石構造の立方晶を維持することが困難となるため、酸
素が脱離できなくなりＯＳＣが低下する。また酸素の吸
蔵・放出能はセリウムの３価と４価の価数変化によるた
め、ジルコニウムの含有率が80モル％以上になると、セ
リウムの絶対量が不足することによりＯＳＣが低下す
る。In the case of a solid solution of ceria and zirconia, the molar ratio of cerium to zirconium is 0.3 ≦ Zr /
(Ce + Zr) ≦ 0.8 is preferable, and 0.4 ≦ Zr / (Ce +
The range of Zr) ≦ 0.6 is particularly preferred. When the content of zirconium is 30 mol% or less, the action of forming a skeleton of zirconium in the solid solution crystal is weakened, and it becomes difficult to maintain a cubic crystal of the fluorite structure due to desorption of oxygen. It cannot be desorbed and the OSC decreases. In addition, since the ability to insert and extract oxygen depends on the change in the valence of trivalent and tetravalent cerium, when the zirconium content exceeds 80 mol%, the OSC is reduced due to the lack of the absolute amount of cerium.
【００３７】担体中の多孔質酸化物と複合酸化物との重
量比は、0.30≦複合酸化物／（複合酸化物＋多孔質酸化
物）≦ 0.7であることが望ましく、 0.4以上 0.6以下の
範囲とすることが特に望ましい。｛複合酸化物／（複合
酸化物＋多孔質酸化物）｝の値が0.30未満では、セリア
−ジルコニア複合酸化物が量的に少なくなって十分なＯ
ＳＣが確保できず、良好な浄化性能が得られない。また
｛複合酸化物／（複合酸化物＋多孔質酸化物）｝の値が
0.7を超えると、貴金属の担持性が低下するとともに貴
金属は主として多孔質酸化物に担持されるため、セリア
−ジルコニア複合酸化物のＯＳＣに代表される助触媒作
用が有効に働かなくなる。The weight ratio between the porous oxide and the composite oxide in the carrier is preferably 0.30 ≦ composite oxide / (composite oxide + porous oxide) ≦ 0.7, and is in the range of 0.4 to 0.6. Is particularly desirable. If the value of {composite oxide / (composite oxide + porous oxide)} is less than 0.30, the amount of ceria-zirconia composite oxide is reduced in quantity and sufficient O
SC cannot be secured, and good purification performance cannot be obtained. Also, the value of {composite oxide / (composite oxide + porous oxide)} is
If it exceeds 0.7, the noble metal carrying property is reduced and the noble metal is mainly carried on the porous oxide, so that the cocatalyst function represented by the OSC of the ceria-zirconia composite oxide does not work effectively.
【００３８】そして上記したように担体を構成すること
により、担体を1000℃で５時間焼成した後の複合酸化物
中のセリア−ジルコニア固溶体の平均結晶子径がＸ線回
折による測定で10nm以下となり、過酷な耐久試験後にも
セリア−ジルコニア複合酸化物の比表面積が高く維持さ
れ高い浄化性能を維持することができる。By configuring the support as described above, the average crystallite size of the ceria-zirconia solid solution in the composite oxide after firing the support at 1000 ° C. for 5 hours becomes 10 nm or less as measured by X-ray diffraction. Even after a severe durability test, the specific surface area of the ceria-zirconia composite oxide is maintained high, and high purification performance can be maintained.
【００３９】担体の一部を構成する多孔質酸化物として
は、アルミナ、ゼオライト、モルデナイト、ＦＳＭ、ア
ルミナ−ジルコニア複合酸化物、シリカ、ジルコニア、
チタニア、シリカ−アルミナなど、従来の排ガス浄化用
触媒の担体として用いられている多孔質酸化物を用いる
ことができる。この多孔質酸化物の粒径は特に制限され
ないが、比表面積が５〜 300m2/gの範囲が最適であり、
この範囲を外れると貴金属の担持割合に偏りを生じ、活
性が低下したり複合酸化物粉末の高分散化を図ることが
困難となる場合がある。なお担体には、混合粉末以外に
含浸法で添加された成分あるいはゾルとして添加された
成分を含んでもよい。The porous oxide constituting a part of the carrier includes alumina, zeolite, mordenite, FSM, alumina-zirconia composite oxide, silica, zirconia,
A porous oxide such as titania and silica-alumina, which has been used as a carrier of a conventional catalyst for purifying exhaust gas, can be used. The particle size of the porous oxide is not particularly limited, but the specific surface area is optimally in the range of 5 to 300 m 2 / g,
If the ratio is out of this range, the loading ratio of the noble metal may be biased, and the activity may be reduced or it may be difficult to achieve a high dispersion of the composite oxide powder. The carrier may contain components added by the impregnation method or components added as a sol in addition to the mixed powder.
【００４０】また担体に担持される貴金属としては、P
t、Rh、Pd、Irなど、従来の排ガス浄化用触媒に用いら
れている貴金属を用いることができる。この貴金属の担
持量は貴金属種によって異なるが、担体に対して 0.1〜
20重量％の範囲とするのが好ましい。貴金属の担持量が
これより少ないと十分な浄化活性が得られず、これより
多くなっても浄化活性が飽和するとともにコストが高騰
する。As the noble metal supported on the carrier, P
Precious metals such as t, Rh, Pd, and Ir used in conventional exhaust gas purifying catalysts can be used. The amount of the noble metal supported varies depending on the type of the noble metal.
Preferably, it is in the range of 20% by weight. If the supported amount of the noble metal is less than this, sufficient purification activity cannot be obtained, and if it is more than this, the purification activity is saturated and the cost rises.
【００４１】本発明にいう複合酸化物を製造するには、
例えば特開平10−182155号公報に開示の製造方法を利用
することができる。すなわち、少なくともAl、Ce及びZr
の塩溶液から共沈法により短時間で酸化物前駆体を調製
し、それを大気中で焼成することによって複合酸化物を
製造することができる。またAl、Ce及びZrをアルコキシ
ドで供給し、ゾルゲル法にて酸化物前駆体を製造しても
よい。In order to produce the composite oxide according to the present invention,
For example, the manufacturing method disclosed in JP-A-10-182155 can be used. That is, at least Al, Ce and Zr
A composite oxide can be produced by preparing an oxide precursor in a short time from a salt solution of the above by a coprecipitation method and calcining it in the air. Alternatively, Al, Ce and Zr may be supplied as alkoxides, and the oxide precursor may be produced by a sol-gel method.
【００４２】そして本発明の排ガス浄化用触媒を製造す
るには、上記複合酸化物の粉末と多孔質酸化物の粉末を
混合して混合粉末とし、それをアルミナゾル、ベーマイ
ト、硝酸アルミニウムなどのバインダ及び水と混合して
スラリーとする。このスラリーを用いてコージエライト
や金属箔から形成されたハニカム形状の担体基材にウォ
ッシュコートし、それを乾燥・焼成してコート層を形成
する。そして貴金属塩や貴金属錯体の溶液を用いてコー
ト層に貴金属を吸着担持することで、本発明の排ガス浄
化用触媒を製造することができる。バインダとしてはシ
リカゾル、ジルコニアゾル、チタニアゾルあるいはこれ
らの金属元素の塩溶液を用いることもできる。To produce the exhaust gas purifying catalyst of the present invention, the mixed oxide powder and the porous oxide powder are mixed to form a mixed powder, which is then mixed with a binder such as alumina sol, boehmite, aluminum nitrate and the like. Mix with water to form a slurry. This slurry is used to wash coat a honeycomb-shaped carrier substrate formed of cordierite or metal foil, and then dried and fired to form a coat layer. Then, the catalyst for exhaust gas purification of the present invention can be manufactured by adsorbing and supporting a noble metal on the coat layer using a solution of a noble metal salt or a noble metal complex. As the binder, silica sol, zirconia sol, titania sol or a salt solution of these metal elements can be used.
【００４３】また複合酸化物粉末と多孔質酸化物粉末と
の混合粉末に貴金属塩溶液などを含浸し、それをそのま
ま、又は濾過・乾燥あるいは蒸発・乾固して貴金属担持
粉末とする。この貴金属担持粉末を担体基材にコートし
てもよい。また、複合酸化物の酸化物前駆体の調製時に
溶液中に貴金属塩などを共存させることで、複合酸化物
に貴金属を担持し、それと多孔質酸化物粉末とを混合し
て貴金属担持粉末とすることもできる。また触媒層を多
孔質化するため、コート層形成用スラリーに有機物やカ
ーボン粉末を添加しておいてもよい。A mixed powder of the composite oxide powder and the porous oxide powder is impregnated with a noble metal salt solution or the like, and is used as it is or is filtered, dried or evaporated and dried to obtain a noble metal-supported powder. This noble metal-carrying powder may be coated on a carrier substrate. Also, by preparing a noble metal salt or the like in the solution at the time of preparing the oxide precursor of the composite oxide, the noble metal is supported on the composite oxide, and then mixed with the porous oxide powder to form a noble metal-supported powder. You can also. Further, in order to make the catalyst layer porous, an organic substance or carbon powder may be added to the slurry for forming the coat layer.
【００４４】[0044]
【実施例】以下、実施例及び比較例により本発明を具体
的に説明する。The present invention will be specifically described below with reference to examples and comparative examples.
【００４５】（実施例１）硝酸アルミニウム、硝酸セリ
ウム、オキシ硝酸ジルコニル及び硝酸ランタンを、式
（３）のａ＝ 0.5、ｂ＝ 0.5、ｄ＝ 0.007となる比率で
溶解した高濃度の水溶液（水溶液中に含まれる焼成後の
固形分約10重量％）を調製した。この水溶液に、セリウ
ムの 1.2倍等量の過酸化水素を含む過酸化水素水を加え
て撹拌混合した後、短時間でアンモニア水を添加して中
和し、水酸化セリウム、水酸化ジルコニウム、水酸化ラ
ンタン及び水酸化アルミニウムの沈殿を含む懸濁液を得
た。これを 300℃で５時間仮焼し 700℃で５時間焼成し
た。得られた粉末を水とともにボールミルに投入し、50
体積％以上の粉末の粒子径が15μｍ以下となるまで破砕
し複合酸化物粉末を調製した。なお、ここでは 700℃で
焼成したが、酸化物を形成できる 600〜1100℃程度で焼
成してもよい。Example 1 A high-concentration aqueous solution (aqueous solution) in which aluminum nitrate, cerium nitrate, zirconyl oxynitrate and lanthanum nitrate were dissolved at a ratio of a = 0.5, b = 0.5 and d = 0.007 in the formula (3) The solid content after firing contained therein was about 10% by weight). To this aqueous solution was added a hydrogen peroxide solution containing hydrogen peroxide in an amount equivalent to 1.2 times the amount of cerium, followed by stirring and mixing.Ammonia water was added in a short time to neutralize the solution, and cerium hydroxide, zirconium hydroxide, and water were added. A suspension containing a precipitate of lanthanum oxide and aluminum hydroxide was obtained. This was calcined at 300 ° C. for 5 hours and calcined at 700 ° C. for 5 hours. The obtained powder is put into a ball mill together with water, and
The powder was crushed until the particle size of the powder of not less than 15% by volume became 15 μm or less to prepare a composite oxide powder. In this case, the firing is performed at 700 ° C., but the firing may be performed at about 600 to 1100 ° C. at which an oxide can be formed.
【００４６】次に、上記複合酸化物粉末 100重量部に対
し、多孔質酸化物粉末としての市販の耐熱性活性アルミ
ナ粉末（比表面積 180m2/g） 100重量部、硝酸アルミニ
ウム９水和物20重量部、ベーマイト（ AlO(OH)）５重量
部及び焼成後の固形分が50重量％になる量の水を加え、
アトライターで約３分間混合してスラリーを調製した。
スラリーを粉砕した後の平均粒子径は７μｍであった。Next, with respect to 100 parts by weight of the composite oxide powder, 100 parts by weight of a commercially available heat-resistant activated alumina powder (specific surface area: 180 m 2 / g) as a porous oxide powder, aluminum nitrate nonahydrate 20 parts Parts by weight, 5 parts by weight of boehmite (AlO (OH)) and water in such an amount that the solid content after firing is 50% by weight,
A slurry was prepared by mixing with an attritor for about 3 minutes.
The average particle size after pulverizing the slurry was 7 μm.
【００４７】容積 1.3Ｌのコージエライト製のハニカム
形状の担体基材を用意し、このスラリーに浸漬後引き上
げて余分なスラリーを吹き払い、乾燥後 650℃で１時間
焼成してコート層を形成した。コート層は、担体基材１
リットル当たり 200ｇ形成した。A 1.3 L cordierite honeycomb-shaped carrier base material was prepared, dipped in the slurry, pulled up, blown off excess slurry, dried and fired at 650 ° C. for 1 hour to form a coat layer. The coating layer is made of the carrier substrate 1
200 g formed per liter.
【００４８】そしてコート層をもつ担体基材を所定濃度
の硝酸白金水溶液に浸漬し、引き上げて余分な液滴を吹
き払って乾燥後 250℃で１時間焼成してPtを担持した。
次いで所定濃度の硝酸ロジウム水溶液に浸漬し、同様に
してRhを担持した。担体基材１リットル当たりPtは 1.5
ｇ担持し、Rhは 0.3ｇ担持した。Then, the carrier substrate having the coating layer was immersed in an aqueous solution of platinum nitrate having a predetermined concentration, lifted up, blown off extra droplets, dried and baked at 250 ° C. for 1 hour to carry Pt.
Next, it was immersed in an aqueous solution of rhodium nitrate having a predetermined concentration, and Rh was supported in the same manner. Pt 1.5 per liter of carrier substrate
g and 0.3 g of Rh.
【００４９】得られた実施例１の排ガス浄化用触媒を排
気量２リットルのガソリンエンジンの排気管に取付け、
欧州走行を模した走行パターンで走行する促進耐久走行
試験を 100時間行った。このときの触媒床最高温度は約
1000℃となる。The obtained exhaust gas purifying catalyst of Example 1 was attached to the exhaust pipe of a 2-liter gasoline engine,
An accelerated endurance running test was performed for 100 hours in a running pattern simulating European driving. The maximum catalyst bed temperature at this time is about
It will be 1000 ° C.
【００５０】その後、欧州走行を模した走行時の排ガス
を、触媒の上流部と下流部で同時に測定し、排ガス中の
HC、CO、及びNOx の浄化率を測定して平均浄化率を算出
した。結果を表１に示す。Thereafter, the exhaust gas during traveling simulating European traveling was measured at the upstream and downstream of the catalyst at the same time.
HC, CO, and averages were calculated purification ratio by measuring the purification rate of NO x. Table 1 shows the results.
【００５１】（実施例２）多孔質酸化物としての活性ア
ルミナ粉末に代えて比表面積50m2/gのジルコニア粉末を
同量用い、かつ硝酸アルミニウムとベーマイトの代わり
にジルコニアゾル（ZrO2：10重量％） 100重量部を用い
たこと以外は実施例１と同様にして、実施例２の排ガス
浄化用触媒を調製した。そして実施例１と同様に平均浄
化率を測定し、結果を表１に示す。Example 2 The same amount of zirconia powder having a specific surface area of 50 m 2 / g was used in place of activated alumina powder as a porous oxide, and zirconia sol (ZrO 2 : 10 wt.) Was used in place of aluminum nitrate and boehmite. %) An exhaust gas purifying catalyst of Example 2 was prepared in the same manner as in Example 1 except that 100 parts by weight was used. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００５２】（実施例３）硝酸アルミニウム、硝酸セリ
ウム及びオキシ硝酸ジルコニルを、式（３）のａ＝ 0.
5、ｂ＝0.33となる比率で溶解した高濃度の水溶液を用
いたこと以外は実施例１と同様にして、実施例３の排ガ
ス浄化用触媒を調製した。そして実施例１と同様に平均
浄化率を測定し、結果を表１に示す。(Example 3) Aluminum nitrate, cerium nitrate and zirconyl oxynitrate were prepared by substituting a = 0.
5. Exhaust gas purification catalyst of Example 3 was prepared in the same manner as in Example 1 except that a high concentration aqueous solution dissolved at a ratio of b = 0.33 was used. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００５３】（実施例４）硝酸アルミニウム、硝酸セリ
ウム、オキシ硝酸ジルコニル及び硝酸イットリウムを式
（２）のａ＝ 0.5、ｂ＝ 0.6、ｃ＝0.05となる比率で溶
解した高濃度の水溶液を用いたこと以外は実施例１と同
様にして、実施例４の排ガス浄化用触媒を調製した。そ
して実施例１と同様に平均浄化率を測定し、結果を表１
に示す。Example 4 A high-concentration aqueous solution in which aluminum nitrate, cerium nitrate, zirconyl oxynitrate and yttrium nitrate were dissolved at a ratio of a = 0.5, b = 0.6 and c = 0.05 in the formula (2) was used. Except for this, the exhaust gas-purifying catalyst of Example 4 was prepared in the same manner as in Example 1. Then, the average purification rate was measured in the same manner as in Example 1, and the results were shown in Table 1.
Shown in
【００５４】（実施例５）硝酸アルミニウム、硝酸セリ
ウム、オキシ硝酸ジルコニル、硝酸イットリウム及び硝
酸ランタンを、式（４）のａ＝ 0.5、ｂ＝ 0.5、ｃ＝0.
05、ｄ＝ 0.015となる比率で溶解した高濃度の水溶液を
調製した。この水溶液を用いて共沈させたこと以外は実
施例１と同様にして、実施例５の排ガス浄化用触媒を調
製した。そして実施例１と同様に平均浄化率を測定し、
結果を表１に示す。(Example 5) Aluminum nitrate, cerium nitrate, zirconyl oxynitrate, yttrium nitrate and lanthanum nitrate were prepared by a = 0.5, b = 0.5 and c = 0 in formula (4).
05, a high concentration aqueous solution dissolved at a ratio of d = 0.015 was prepared. An exhaust gas purifying catalyst of Example 5 was prepared in the same manner as in Example 1 except that coprecipitation was performed using this aqueous solution. Then, the average purification rate was measured in the same manner as in Example 1,
Table 1 shows the results.
【００５５】（実施例６）実施例１と同様にして調製さ
れた複合酸化物粉末に、所定濃度の硝酸パラジウム水溶
液の所定量を含浸させ、濾過・乾燥・ 250℃で焼成して
Pdを担持した。このPd担持複合酸化物粉末 100重量部に
対し、多孔質酸化物粉末としての実施例１と同様の活性
アルミナ粉末 100重量部、硝酸アルミニウム９水和物20
重量部、ベーマイト５重量部を加え、アトライターで約
３分間混合してスラリーを調製した。Example 6 A composite oxide powder prepared in the same manner as in Example 1 was impregnated with a predetermined amount of an aqueous solution of palladium nitrate having a predetermined concentration, filtered, dried and calcined at 250 ° C.
Pd was loaded. With respect to 100 parts by weight of the Pd-supported composite oxide powder, 100 parts by weight of the same activated alumina powder as in Example 1 as the porous oxide powder, and aluminum nitrate 9 hydrate 20
Parts by weight and 5 parts by weight of boehmite were added and mixed with an attritor for about 3 minutes to prepare a slurry.
【００５６】このスラリーを用い、実施例１と同様にし
てコート層を形成し、次いで所定濃度の硝酸ロジウム水
溶液に浸漬し、引き上げて余分な液滴を吹き払い乾燥し
てRhを担持して、実施例６の排ガス浄化用触媒を調製し
た。担体基材１リットル当たりPdは 1.5ｇ担持され、Rh
は 0.3ｇ担持されている。そして実施例１と同様に平均
浄化率を測定し、結果を表１に示す。Using this slurry, a coat layer was formed in the same manner as in Example 1, and then immersed in an aqueous solution of rhodium nitrate having a predetermined concentration, pulled up, blown off excess droplets, and dried to carry Rh. An exhaust gas purifying catalyst of Example 6 was prepared. 1.5 g of Pd is supported per liter of carrier substrate, and Rh
Is supported by 0.3 g. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００５７】（実施例７）硝酸アルミニウム、硝酸セリ
ウム、オキシ硝酸ジルコニル及び硝酸ランタンを、式
（３）のａ＝ 0.5、ｂ＝ 0.5、ｄ＝ 0.015となる比率で
溶解した高濃度の水溶液を調製した。この水溶液を用い
て共沈させたこと、及び活性アルミナ粉末に代えてモル
デナイトを混合したこと以外は実施例６と同様にして実
施例７の排ガス浄化用触媒を調製した。担体基材１リッ
トル当たりPdは 1.5ｇ担持され、Rhは0.3ｇ担持されて
いる。そして実施例１と同様に平均浄化率を測定し、結
果を表１に示す。Example 7 A high-concentration aqueous solution was prepared by dissolving aluminum nitrate, cerium nitrate, zirconyl oxynitrate and lanthanum nitrate in the ratio of a = 0.5, b = 0.5 and d = 0.015 in the formula (3). did. An exhaust gas purifying catalyst of Example 7 was prepared in the same manner as in Example 6, except that the aqueous solution was coprecipitated and mordenite was mixed instead of the activated alumina powder. 1.5 g of Pd and 0.3 g of Rh are supported per liter of the carrier substrate. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００５８】（実施例８）硝酸アルミニウム、硝酸セリ
ウム、オキシ硝酸ジルコニル及び硝酸ランタンを、式
（３）のａ＝ 0.5、ｂ＝ 0.5、ｄ＝ 0.015となる比率で
溶解し、さらに硝酸パラジウムを溶解した高濃度の水溶
液を調製した。この水溶液を用いて共沈させたこと以外
は実施例６と同様にしてPd担持複合酸化物粉末を調製し
た。Example 8 Aluminum nitrate, cerium nitrate, zirconyl oxynitrate and lanthanum nitrate were dissolved at a ratio of a = 0.5, b = 0.5 and d = 0.015 in the formula (3), and palladium nitrate was further dissolved. A highly concentrated aqueous solution was prepared. A Pd-supported composite oxide powder was prepared in the same manner as in Example 6, except that coprecipitation was performed using this aqueous solution.
【００５９】このPd担持複合酸化物粉末 100重量部に対
し、多孔質酸化物粉末としての実施例１と同様の活性ア
ルミナ粉末 100重量部、硝酸アルミニウム９水和物20重
量部、ベーマイト５重量部を加え、アトライターで約３
分間混合してスラリーを調製した。Based on 100 parts by weight of the Pd-supported composite oxide powder, 100 parts by weight of activated alumina powder as in Example 1 as a porous oxide powder, 20 parts by weight of aluminum nitrate nonahydrate, and 5 parts by weight of boehmite And add about 3
Mix for minutes to prepare a slurry.
【００６０】このスラリーを用い、実施例１と同様にし
てコート層を形成し、さらにPtとRhを担持して実施例８
の排ガス浄化用触媒を調製した。担体基材１リットル当
たりPdは 1.5ｇ担持され、Ptは 1.5ｇ、Rhは 0.3ｇ担持
されている。そして実施例１と同様に平均浄化率を測定
し、結果を表１に示す。Using this slurry, a coat layer was formed in the same manner as in Example 1, and Pt and Rh were further supported.
Was prepared. 1.5 g of Pd, 1.5 g of Pt and 0.3 g of Rh are supported per liter of the carrier substrate. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００６１】（実施例９）硝酸アルミニウム、硝酸セリ
ウム、オキシ硝酸ジルコニル及び硝酸ランタンを、式
（３）のａ＝ 0.5、ｂ＝ 0.5、ｄ＝ 0.015となる比率で
溶解し、さらに硝酸パラジウムを溶解した高濃度の水溶
液を調製した。この水溶液を用いて共沈させたこと以外
は実施例６と同様にしてPd担持複合酸化物粉末を調製し
た。Example 9 Aluminum nitrate, cerium nitrate, zirconyl oxynitrate and lanthanum nitrate were dissolved in a ratio of a = 0.5, b = 0.5 and d = 0.015 in the formula (3), and palladium nitrate was further dissolved. A highly concentrated aqueous solution was prepared. A Pd-supported composite oxide powder was prepared in the same manner as in Example 6, except that coprecipitation was performed using this aqueous solution.
【００６２】このPd担持複合酸化物粉末 100重量部に対
し、実施例１と同様の活性アルミナ粉末50重量部と、多
孔質酸化物粉末としての比表面積70m2/gのアルミナ−ジ
ルコニア複合酸化物粉末50重量部と、硝酸アルミニウム
９水和物20重量部及びベーマイト５重量部を加え、アト
ライターで約３分間混合してスラリーを調製した。With respect to 100 parts by weight of the Pd-supported composite oxide powder, 50 parts by weight of the same activated alumina powder as in Example 1 and an alumina-zirconia composite oxide having a specific surface area of 70 m 2 / g as a porous oxide powder 50 parts by weight of the powder, 20 parts by weight of aluminum nitrate 9-hydrate and 5 parts by weight of boehmite were added, and mixed with an attritor for about 3 minutes to prepare a slurry.
【００６３】このスラリーを用い、実施例１と同様にし
てコート層を形成し、さらにPtとRhを担持して実施例９
の排ガス浄化用触媒を調製した。担体基材１リットル当
たりPdは 1.5ｇ担持され、Ptは 1.5ｇ、Rhは 0.3ｇ担持
されている。そして実施例１と同様に平均浄化率を測定
し、結果を表１に示す。Using this slurry, a coat layer was formed in the same manner as in Example 1, and Pt and Rh were further supported.
Was prepared. 1.5 g of Pd, 1.5 g of Pt and 0.3 g of Rh are supported per liter of the carrier substrate. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００６４】（比較例１〜５）硝酸アルミニウム、硝酸
セリウム及びオキシ硝酸ジルコニルを、式（３）のａ＝
2.6、ｂ＝ 0.5、ｄ＝０となる比率で溶解した高濃度の
水溶液を用いたこと以外は実施例１と同様にして、比較
例１の排ガス浄化用触媒を調製した。そして実施例１と
同様に平均浄化率を測定し、結果を表１に示す。(Comparative Examples 1 to 5) Aluminum nitrate, cerium nitrate and zirconyl oxynitrate were replaced by a =
An exhaust gas purifying catalyst of Comparative Example 1 was prepared in the same manner as in Example 1 except that a high-concentration aqueous solution dissolved at a ratio of 2.6, b = 0.5 and d = 0 was used. Then, the average purification rate was measured in the same manner as in Example 1, and the results are shown in Table 1.
【００６５】また、ａ〜ｄを本発明の範囲以外としたこ
と以外は実施例１〜４と同様の方法で調製した比較例２
〜５の組成とその結果を、表１に示す。Comparative Example 2 prepared in the same manner as in Examples 1 to 4 except that a to d were outside the scope of the present invention.
Table 1 shows the compositions of Nos. To 5 and the results.
【００６６】＜評価＞<Evaluation>
【００６７】[0067]
【表１】 [Table 1]
【００６８】表１からわかるように、各実施例の排ガス
浄化用触媒は1000℃で 100時間という過酷な耐久試験後
にも95〜99％というきわめて高い平均浄化率を示し、比
較例１〜５の触媒に比べて耐久性にきわめて優れている
ことがわかる。As can be seen from Table 1, the exhaust gas purifying catalysts of the examples exhibited extremely high average purifying rates of 95 to 99% even after a severe durability test at 1000 ° C. for 100 hours. It can be seen that the durability is extremely superior to that of the catalyst.
【００６９】またＸ線回折の結果、各実施例の触媒では
セリウムとジルコニウムはほぼ均一な固溶体を形成し、
その平均結晶子径は約７nmであり、ZrO2の固溶度は85％
以上であった。As a result of X-ray diffraction, cerium and zirconium formed almost uniform solid solutions in the catalysts of the respective examples.
Its average crystallite diameter is about 7 nm, and the solid solubility of ZrO 2 is 85%.
That was all.
【００７０】またコート層の断面を研磨して電子顕微鏡
で観察した結果、セリウムとジルコニウムの固溶体がア
ルミナ中に高分散に分布し、さらにこの複合酸化物粉末
がアルミナ粉末又はアルミナ−ジルコニア複合酸化物粉
末に取り囲まれた状態で分散していることが確認され
た。As a result of polishing the cross section of the coat layer and observing it with an electron microscope, it was found that a solid solution of cerium and zirconium was highly dispersed in alumina, and that this composite oxide powder was alumina powder or alumina-zirconia composite oxide. It was confirmed that the particles were dispersed in a state surrounded by the powder.
【００７１】さらにコート層を掻き取った粉末の比表面
積を測定したところ、実施例２の触媒で18m2／ｇ、その
他の実施例の触媒で約70m2/g以上と大きい比表面積を有
していることが確認された。そしてその粉末のＯＳＣを
測定した結果、 300℃におけるセリウム１モル当たりの
ＯＳＣは0.09（モル−O2／モル−Ce）以上という高い値
を示すことが確認された。Further, when the specific surface area of the powder from which the coat layer was scraped off was measured, the catalyst of Example 2 had a large specific surface area of 18 m 2 / g, and the catalysts of the other examples had a large specific surface area of about 70 m 2 / g or more. It was confirmed that. As a result of measuring the OSC of the powder, it was confirmed that the OSC per mol of cerium at 300 ° C. showed a high value of 0.09 (mol-O 2 / mol-Ce) or more.
【００７２】なおＯＳＣの測定方法としては、触媒を石
英反応管に充填し、赤外線イメージ炉により 300℃での
測定を行った。具体的には、触媒 0.1〜１ｇに１％H2＋
Heガス 100cc／分と１％O2＋Heガス50cc／分を数十秒〜
数分（主に 2.5分）間隔で交互に流通させ、四重極型質
量分析計により触媒出ガスを分析し、各温度で13分間測
定して、各温度での２サイクル目にて、O2＋Heガスから
H2＋Heガスへガスを切り換えたた時の時間遅れから、触
媒に吸蔵されていた酸素量を算出した。As a method for measuring the OSC, the catalyst was filled in a quartz reaction tube, and the measurement was performed at 300 ° C. using an infrared image furnace. Specifically, 1% H 2 + is added to 0.1 to 1 g of the catalyst.
He gas 100cc / min and 1% O 2 + He gas 50cc / min for several tens of seconds
The mixture was alternately circulated at intervals of several minutes (mainly 2.5 minutes), and the outgas of the catalyst was analyzed by a quadrupole mass spectrometer, and measured at each temperature for 13 minutes. 2 From + He gas
From the time delay when the gas was switched to H 2 + He gas, the amount of oxygen stored in the catalyst was calculated.
【００７３】以上の結果より、各実施例の排ガス浄化用
触媒は耐久試験後にもセリアージルコニア固溶体が高分
散しており比表面積も大きいため、そのＯＳＣが高く発
現されることにより高い浄化性能が維持できたことが明
らかである。これは複合酸化物のモル比ａ〜ｄの値を本
発明の組成範囲としたことに起因していると考えられ
る。From the above results, since the ceria-zirconia solid solution is highly dispersed and has a large specific surface area even after the endurance test, the exhaust gas purifying catalysts of the respective examples exhibit high purification performance due to their high OSC. It is clear that it was maintained. This is considered to be due to the fact that the values of the molar ratios a to d of the composite oxide were set in the composition range of the present invention.
【００７４】（実施例10〜28及び比較例６〜10）組成が
異なること以外は実施例１〜４と同様の方法で、表２に
示す25種類の粉末を合成し、大気中にて表２に示す 950
〜1100℃の条件でそれぞれ焼成を行った。(Examples 10 to 28 and Comparative Examples 6 to 10) Except for different compositions, 25 kinds of powders shown in Table 2 were synthesized in the same manner as in Examples 1 to 4, and 950 shown in 2
The firing was performed under the conditions of 11100 ° C.
【００７５】焼成後の各試料について、含まれるセリア
−ジルコニア固溶体中のジルコニアの固溶度、セリア−
ジルコニア固溶体の平均結晶子径、アルミナとセリアと
ジルコニアの複合酸化物の比表面積をそれぞれ測定し、
結果を表２に示す。なお実施例23については、実施例１
と同様の方法の他に通常行われるゾルゲル法を用いても
合成を行ったが、どちらの合成法でもほぼ同様の測定値
が得られたことを付記しておく。For each sample after firing, the solid solubility of zirconia in the contained ceria-zirconia solid solution,
The average crystallite diameter of the zirconia solid solution, the specific surface area of the composite oxide of alumina, ceria and zirconia were measured, respectively.
Table 2 shows the results. In addition, about Example 23, Example 1
Although the synthesis was carried out using a sol-gel method which is usually performed in addition to the same method as in the above, it should be noted that almost the same measured values were obtained by either of the synthesis methods.
【００７６】＜評価＞<Evaluation>
【００７７】[0077]
【表２】 [Table 2]
【００７８】表２より、実施例10〜28の粉末は、大気中
での高温焼成後においても、高いZrO2固溶度と高い比表
面積を有し、セリア−ジルコニア固溶体の平均結晶子径
も小さい。As can be seen from Table 2, the powders of Examples 10 to 28 have high ZrO 2 solid solubility and high specific surface area even after firing at a high temperature in the air, and have an average crystallite diameter of ceria-zirconia solid solution. small.
【００７９】一方実施例28と比較例６〜10の粉末では、
実施例28で明らかなように1100℃焼成後にZrO2の固溶度
が十分でなかったり、比較例６〜９で顕著なようにセリ
ア−ジルコニア固溶体の平均結晶子径が大きくなったり
比表面積が小さくなったりする不具合がある。またアル
ミナが多い組成の比較例10の場合には、含まれるセリア
量が相対的に少なくなるためＯＳＣが低く、その結果、
変動雰囲気下では高い触媒性能が得られない。On the other hand, in the powders of Example 28 and Comparative Examples 6 to 10,
As evident in Example 28, the solid solubility of ZrO 2 after firing at 1100 ° C. was not sufficient, or the average crystallite diameter of the ceria-zirconia solid solution was large or the specific surface area was notable in Comparative Examples 6 to 9. There is a problem that it becomes smaller. In the case of Comparative Example 10 having a large amount of alumina, the amount of ceria contained was relatively small, so that the OSC was low. As a result,
High catalytic performance cannot be obtained in a fluctuating atmosphere.
【００８０】なお表２において、ZrO2の固溶度が 100を
超える値のものがある。これは、前述の（６）式を用い
て、セリア−ジルコニア固溶体（立方晶）３１１回折線
から簡易的に求めているためである。なぜならＹやLa
は、アルミナとセリア−ジルコニア固溶体の両者に固溶
するため、ＹとLaのイオン半径の違いによりセリア−ジ
ルコニア固溶体の格子定数が変化するからである。しか
しその影響は10％以下であるので、便宜上この影響は無
視して算出している。In Table 2, ZrO 2 has a solid solubility exceeding 100. This is because it is simply obtained from the ceria-zirconia solid solution (cubic) 311 diffraction line using the above-mentioned equation (6). Because Y and La
Is because the solid solution forms in both alumina and the ceria-zirconia solid solution, so that the lattice constant of the ceria-zirconia solid solution changes depending on the difference in ionic radius between Y and La. However, since the effect is less than 10%, this effect is ignored for the sake of convenience.
【００８１】ＯＳＣの測定方法を以下に示す。The method of measuring the OSC is described below.
【００８２】1000℃で20時間耐久試験後の実施例10〜28
及び比較例６〜10の複合酸化物 100ｇ当たり白金を含浸
法により１ｇ担持した。その触媒粉末を圧粉成形した
後、直径 0.5〜１ｍｍのペレット触媒を調製した。この
触媒 0.3ｇを用いて、実施例２の触媒と同様の方法でＯ
ＳＣを測定した。測定結果から単位重量当たりのＯＳＣ
を算出し、実施例11の複合酸化物を用いた触媒のＯＳＣ
を 100とした相対値で表２に示した。Examples 10 to 28 after endurance test at 1000 ° C. for 20 hours
In addition, 1 g of platinum was supported by impregnation per 100 g of the composite oxide of Comparative Examples 6 to 10. After compacting the catalyst powder, a pellet catalyst having a diameter of 0.5 to 1 mm was prepared. Using 0.3 g of this catalyst, O was prepared in the same manner as the catalyst of Example 2.
SC was measured. OSC per unit weight from measurement results
Was calculated, and the OSC of the catalyst using the composite oxide of Example 11 was calculated.
Are shown in Table 2 as relative values with respect to 100.
【００８３】表２より、固溶度が高くかつ実施例の組成
範囲内の触媒は、ＯＳＣが高いことが明らかである。From Table 2, it is clear that the catalyst having a high solid solubility and within the composition range of the example has a high OSC.
【００８４】＜粒径の影響＞次に、混合粉末の粒径の影
響を調査した。<Effect of Particle Size> The effect of the particle size of the mixed powder was examined.
【００８５】アトライターによる破砕混合時間を変えた
こと以外は実施例１と同様にして、平均粒径２μｍ、５
μｍ、 7.7μｍ及び 8.8μｍの４種類の混合粉末を調製
した。そしてそれぞれの混合粉末を用い、実施例１と同
様にして４種類の排ガス浄化用触媒を調製した。An average particle diameter of 2 μm, 5 μm,
Four types of mixed powders of μm, 7.7 μm and 8.8 μm were prepared. Then, four types of exhaust gas purifying catalysts were prepared in the same manner as in Example 1 using the respective mixed powders.
【００８６】これらの排ガス浄化用触媒を実施例１と同
様に排気管に装着し、同様の促進耐久走行試験を10時間
行った。その後の触媒断面を電子顕微鏡で観察した。そ
の結果、図１に示すように、平均粒径２μｍの混合粉末
を用いたものではコート層に大きなひび割れが観察さ
れ、剥離も生じていた。These exhaust gas purifying catalysts were attached to the exhaust pipe in the same manner as in Example 1, and the same accelerated durability running test was performed for 10 hours. Thereafter, the cross section of the catalyst was observed with an electron microscope. As a result, as shown in FIG. 1, in the case of using the mixed powder having an average particle size of 2 μm, large cracks were observed in the coat layer, and peeling occurred.
【００８７】次に触媒端面から圧力0.1MPaで空気を吹き
付け、その後の触媒断面を電子顕微鏡で観察した。その
結果、図２に示すように、平均粒径５μｍの混合粉末を
用いたものではコート層に一部ひび割れが観察される
が、剥離はごく一部となった。Next, air was blown from the end face of the catalyst at a pressure of 0.1 MPa, and the cross section of the catalyst was observed with an electron microscope. As a result, as shown in FIG. 2, when the mixed powder having an average particle size of 5 μm was used, some cracks were observed in the coat layer, but peeling was very small.
【００８８】さらに平均粒径が 7.7μｍ及び 8.8μｍの
混合粉末を用いたものでは、図３及び図４に示すよう
に、空気吹き付け後にもコート層にひび割れや剥離は観
察されず、コート層の強度に優れていた。Further, in the case of using the mixed powder having the average particle diameters of 7.7 μm and 8.8 μm, as shown in FIGS. 3 and 4, no cracking or peeling was observed in the coat layer even after air blowing, and The strength was excellent.
【００８９】また上記４種類の混合粉末と、その他の４
種類の混合粉末について、レーザー回折／散乱式粒度分
布測定装置を用いて粒度分布をそれぞれ測定するととも
に、剥離の程度を相対評価し、結果を表３に示す。The above four kinds of mixed powders and the other four
For each type of mixed powder, the particle size distribution was measured using a laser diffraction / scattering type particle size distribution measuring device, and the degree of peeling was relatively evaluated. The results are shown in Table 3.
【００９０】[0090]
【表３】 [Table 3]
【００９１】表３から、粒径５μｍ以上の粉末が30％以
上含まれると剥離やひび割れの程度が小さくなることが
わかる。また40％以上、さらには50％以上であることが
好ましいこともわかる。しかし粒径が大きければ良いと
いうものではなく、粒径が５μｍ以上の粉末が85％以上
になると逆に剥離が多くなっている。さらに平均粒子径
としては、 3.5〜20μｍ、好ましくは 4.5〜14μｍ、よ
り好ましくは 5.5〜11μｍ、さらに好ましくは７〜９μ
ｍがよいことがわかる。From Table 3, it can be seen that when 30% or more of powder having a particle size of 5 μm or more is contained, the degree of peeling and cracking is reduced. It is also found that the content is preferably 40% or more, and more preferably 50% or more. However, it is not good that the particle size is large, and peeling increases when the particle size is 5 μm or more when it is 85% or more. Further, the average particle size is 3.5 to 20 μm, preferably 4.5 to 14 μm, more preferably 5.5 to 11 μm, and still more preferably 7 to 9 μm.
It turns out that m is good.
【００９２】（実施例29〜32，比較例11〜13）表４に、
担体中の多孔質酸化物と複合酸化物との重量比に注目し
て実験した結果を示す。実施例28と同等の組成比をもつ
複合酸化物を例として用いたこと、及び複合酸化物とγ
-Al2O3との重量比をそれぞれ変えたこと以外は実施例１
と同様の排ガス浄化用触媒を試作した。この触媒に対
し、実施例１と同様の促進耐久走行試験を 100時間行っ
た。(Examples 29 to 32, Comparative Examples 11 to 13)
The results of an experiment focusing on the weight ratio between the porous oxide and the composite oxide in the carrier are shown. Using a composite oxide having the same composition ratio as in Example 28 as an example, and using a composite oxide and γ
Example 1 except that the weight ratio to -Al 2 O 3 was changed respectively.
An exhaust gas purification catalyst similar to that described above was prototyped. This catalyst was subjected to the same accelerated durability running test as in Example 1 for 100 hours.
【００９３】そして耐久試験前後の触媒の重量差からコ
ート層の剥離率を算出し、結果を表４に示した。また、
耐久試験後の触媒を評価装置に配置し、 300℃における
ＯＳＣを測定した。これも結果を表４に示した。The peel rate of the coat layer was calculated from the difference in weight of the catalyst before and after the durability test. The results are shown in Table 4. Also,
The catalyst after the durability test was placed in an evaluation device, and the OSC at 300 ° C. was measured. The results are also shown in Table 4.
【００９４】さらに、耐久試験後の各触媒を２リットル
のエンジンの排気系にそれぞれ装着し、入りガス温度を
室温から徐々に高め、HCとNOx の浄化率を測定した。そ
してそれぞれの50％浄化温度を算出し、結果を表４に示
した。[0094] Further, each fitted with a respective catalysts after the durability test in an exhaust system of a 2 liter engine, gradually increased incoming gas temperature from room temperature to measure the purification rate of HC and NO x. Then, the respective 50% purification temperatures were calculated, and the results are shown in Table 4.
【００９５】なお、さらに、上記測定後の触媒の一部か
らコート層を掻き取り、比表面積をそれぞれ測定した結
果も表４に示した。Further, Table 4 also shows the results of scraping off the coat layer from a part of the catalyst after the measurement and measuring the specific surface area.
【００９６】[0096]
【表４】 [Table 4]
【００９７】表４から明らかなように、複合酸化物とγ
-Al2O3との重量比を 0.3≦複合酸化物／（複合酸化物＋
γ-Al2O3）≦ 0.7、好ましくは 0.4≦複合酸化物／（複
合酸化物＋γ-Al2O3）≦ 0.6とすることにより、コート
層の剥離率を小さく抑え、高いＯＳＣと50％浄化温度の
上昇を低く抑えることができた。As apparent from Table 4, the composite oxide and γ
-Al 2 O 3 weight ratio 0.3 ≦ composite oxide / (composite oxide +
By setting γ-Al 2 O 3 ) ≦ 0.7, preferably 0.4 ≦ composite oxide / (composite oxide + γ-Al 2 O 3 ) ≦ 0.6, the peeling rate of the coat layer is suppressed to be small, and high OSC and 50% The rise in purification temperature could be kept low.
【００９８】[0098]
【発明の効果】すなわち本発明の排ガス浄化用触媒によ
れば、過酷な耐久試験後にもコート層のひび割れ及びク
ラックの発生が防止されるとともに、セリア−ジルコニ
ア複合酸化物の比表面積が高く高分散状態が維持される
ので、耐久性にきわめて優れている。According to the exhaust gas purifying catalyst of the present invention, cracks and cracks in the coating layer are prevented even after a severe durability test, and the specific surface area of the ceria-zirconia composite oxide is high and the dispersion is high. Since the state is maintained, the durability is extremely excellent.
【図１】平均粒径２μｍの混合粉末を用いた触媒の耐久
試験後の断面の粒子構造を示す顕微鏡写真である。FIG. 1 is a photomicrograph showing the particle structure of a cross section of a catalyst using a mixed powder having an average particle size of 2 μm after a durability test.
【図２】平均粒径５μｍの混合粉末を用いた触媒の耐久
試験後に空気を吹き付けた後の断面の粒子構造を示す顕
微鏡写真である。FIG. 2 is a photomicrograph showing the particle structure of a cross section after blowing air after a durability test of a catalyst using a mixed powder having an average particle size of 5 μm.
【図３】平均粒径 7.7μｍの混合粉末を用いた触媒の耐
久試験後に空気を吹き付けた後の断面の粒子構造を示す
顕微鏡写真である。FIG. 3 is a photomicrograph showing the particle structure of a cross section after blowing air after a durability test of a catalyst using a mixed powder having an average particle size of 7.7 μm.
【図４】平均粒径 8.8μｍの混合粉末を用いた触媒の耐
久試験後に空気を吹き付けた後の断面の粒子構造を示す
顕微鏡写真である。FIG. 4 is a photomicrograph showing the particle structure of a cross section after blowing air after a durability test of a catalyst using a mixed powder having an average particle size of 8.8 μm.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平10−277389（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B01J 21/00 - 38/74 B01D 53/86 B01D 53/94 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-277389 (JP, A) (58) Field surveyed (Int. Cl. 7 , DB name) B01J 21/00-38/74 B01D 53 / 86 B01D 53/94
Claims (9)
る複合酸化物の粉末との混合粉末よりなる担体と、該担
体に担持された貴金属と、からなる排ガス浄化用触媒で
あって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （１） （式（１）においてａ及びｂはモル比を示し、ａは 0.4
〜 2.5、ｂは 0.2〜 0.7の範囲にある） 前記混合粉末には粒径５μｍ以上の粉末が30体積％以上
含まれていることを特徴とする排ガス浄化用触媒。An exhaust gas purifying catalyst comprising: a carrier comprising a mixed powder of a porous oxide powder and a composite oxide powder represented by the formula (1); and a noble metal carried on the carrier. (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (1) (In the formula (1), a and b indicate a molar ratio, and a is 0.4
-2.5, b is in the range of 0.2-0.7) The exhaust gas purifying catalyst characterized in that the mixed powder contains 30% by volume or more of powder having a particle size of 5 μm or more.
る複合酸化物の粉末との混合粉末よりなる担体と、該担
体に担持された貴金属と、からなる排ガス浄化用触媒で
あって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （Y2O3）c （２） （式（２）においてａ、ｂ及びｃはモル比を示し、ａは
0.4〜 2.5、ｂは 0.2〜 0.7、ｃは0.01〜 0.2の範囲に
ある） 前記混合粉末には粒径５μｍ以上の粉末が30体積％以上
含まれていることを特徴とする排ガス浄化用触媒。2. An exhaust gas purifying catalyst comprising a carrier comprising a mixed powder of a porous oxide powder and a composite oxide powder represented by the formula (2), and a noble metal supported on the carrier. (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (Y 2 O 3 ) c (2) (in the formula (2), a, b and c indicate a molar ratio, and a Is
0.4 to 2.5, b is in the range of 0.2 to 0.7 and c is in the range of 0.01 to 0.2) The mixed powder contains 30% by volume or more of powder having a particle size of 5 μm or more.
る複合酸化物の粉末との混合粉末よりなる担体と、該担
体に担持された貴金属と、からなる排ガス浄化用触媒で
あって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （ La2O3）d （３） （式（３）においてａ、ｂ及びｄはモル比を示し、ａは
0.4〜 2.5、ｂは 0.2〜 0.7、ｄは 0.005〜 0.1の範囲
にある） 前記混合粉末には粒径５μｍ以上の粉末が30体積％以上
含まれていることを特徴とする排ガス浄化用触媒。3. An exhaust gas purifying catalyst comprising a carrier comprising a mixed powder of a powder of a porous oxide and a powder of a complex oxide represented by the formula (3), and a noble metal carried on the carrier. Then, (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (La 2 O 3 ) d (3) (in the formula (3), a, b and d indicate a molar ratio, and a Is
0.4 to 2.5, b is in the range of 0.2 to 0.7, and d is in the range of 0.005 to 0.1) The mixed powder contains 30% by volume or more of powder having a particle size of 5 μm or more.
る複合酸化物の粉末との混合粉末よりなる担体と、該担
体に担持された貴金属と、からなる排ガス浄化用触媒で
あって、 （ Al2O3）a （CeO2）b （ZrO2）1-b （Y2O3）c （ La2O3）d （４） （式（４）においてａ、ｂ、ｃ及びｄはモル比を示し、
ａは 0.4〜 2.5、ｂは0.2〜 0.7、ｃは0.01〜 0.2、ｄ
は 0.005〜 0.1の範囲にある） 前記混合粉末には粒径５μｍ以上の粉末が30体積％以上
含まれていることを特徴とする排ガス浄化用触媒。4. An exhaust gas purifying catalyst comprising a carrier comprising a mixed powder of a porous oxide powder and a composite oxide powder represented by the formula (4), and a noble metal carried on the carrier. Then, (Al 2 O 3 ) a (CeO 2 ) b (ZrO 2 ) 1 -b (Y 2 O 3 ) c (La 2 O 3 ) d (4) (in the formula (4), a, b, c And d represent a molar ratio,
a is 0.4 to 2.5, b is 0.2 to 0.7, c is 0.01 to 0.2, d
Is in the range of 0.005 to 0.1) An exhaust gas purifying catalyst characterized in that the mixed powder contains 30% by volume or more of powder having a particle size of 5 µm or more.
を形成し、該複合酸化物中のZrO2の固溶度が50％以上で
あることを特徴とする請求項１〜４のいずれかに記載の
排ガス浄化用触媒。5. The solid oxide of CeO 2 and ZrO 2 in the composite oxide, wherein the solid solubility of ZrO 2 in the composite oxide is 50% or more. The exhaust gas purifying catalyst according to any one of the above.
複合酸化物中のセリア−ジルコニア固溶体の平均結晶子
径がＸ線回折による測定で10nm以下であることを特徴と
する請求項１〜５のいずれかに記載の排ガス浄化用触
媒。6. An average crystallite size of the ceria-zirconia solid solution in the composite oxide after calcining the carrier at 1000 ° C. for 5 hours is 10 nm or less as measured by X-ray diffraction. 6. The exhaust gas purifying catalyst according to any one of claims 1 to 5.
合酸化物との重量比が0.30≦複合酸化物／（複合酸化物
＋多孔質酸化物）≦ 0.7であることを特徴とする請求項
１〜６のいずれかに記載の排ガス浄化用触媒。7. The weight ratio of the porous oxide and the complex oxide in the carrier is 0.30 ≦ complex oxide / (complex oxide + porous oxide) ≦ 0.7. Item 7. The exhaust gas purifying catalyst according to any one of Items 1 to 6.
体にはさらにPt及びRhの少なくとも一方が担持されてい
ることを特徴とする請求項１〜７のいずれかに記載の排
ガス浄化用触媒。8. The exhaust gas purifying apparatus according to claim 1, wherein Pd is carried on the composite oxide, and at least one of Pt and Rh is further carried on the carrier. catalyst.
が85体積％未満の割合で含まれていることを特徴とする
請求項１〜８のいずれかに記載の排ガス浄化用触媒。9. The exhaust gas purifying catalyst according to claim 1, wherein the mixed powder contains a powder having a particle size of 5 μm or more in a proportion of less than 85% by volume.
Priority Applications (2)
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|---|---|---|---|
| JP2000008589A JP3265534B2 (en) | 1999-01-18 | 2000-01-18 | Exhaust gas purification catalyst |
| US09/547,347 US6335305B1 (en) | 1999-01-18 | 2000-04-11 | Catalyst for purifying exhaust gas |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11-9826 | 1999-01-18 | ||
| JP982699 | 1999-01-18 | ||
| JP2000008589A JP3265534B2 (en) | 1999-01-18 | 2000-01-18 | Exhaust gas purification catalyst |
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| JP3265534B2 true JP3265534B2 (en) | 2002-03-11 |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002361090A (en) * | 2001-06-12 | 2002-12-17 | Toyota Motor Corp | Catalyst for cleaning exhaust gas |
| JP2003047849A (en) * | 2001-08-09 | 2003-02-18 | Nissan Motor Co Ltd | Catalyst and method for cleaning exhaust gas |
| US7265076B2 (en) | 2002-12-26 | 2007-09-04 | Matsushita Electric Industrial Co, Ltd. | CO removal catalyst, method of producing CO removal catalyst, hydrogen purifying device and fuel cell system |
| JP4503314B2 (en) * | 2003-03-10 | 2010-07-14 | 株式会社キャタラー | Exhaust gas purification catalyst |
| JP4507717B2 (en) * | 2004-01-16 | 2010-07-21 | マツダ株式会社 | Exhaust gas purification catalyst |
| JP4665458B2 (en) * | 2004-08-20 | 2011-04-06 | トヨタ自動車株式会社 | Exhaust gas purification catalyst and method for producing the same |
| JP2006110485A (en) | 2004-10-15 | 2006-04-27 | Johnson Matthey Japan Inc | Exhaust gas catalyst and exhaust gas trteatment apparatus using the catalyst |
| JP2007275704A (en) * | 2006-04-03 | 2007-10-25 | Johnson Matthey Japan Inc | Exhaust gas catalyst and exhaust gas treating device using the same |
| JP2008100202A (en) * | 2006-10-20 | 2008-05-01 | Cataler Corp | Exhaust gas purifying catalyst |
| EP1985354B1 (en) * | 2007-04-27 | 2012-07-11 | Mazda Motor Corporation | Exhaust gas purification catalyst and manufacturing method thereof |
| JP5278671B2 (en) * | 2008-11-20 | 2013-09-04 | 日産自動車株式会社 | PM oxidation catalyst, diesel particulate filter using the same, and method for producing PM oxidation catalyst |
| JP5900395B2 (en) * | 2012-11-22 | 2016-04-06 | トヨタ自動車株式会社 | Composite oxide particles and exhaust gas purification catalyst using the same |
| WO2015100339A1 (en) * | 2013-12-23 | 2015-07-02 | Rhodia Operations | Inorganic composite oxides and methods of making the same |
| JP6384499B2 (en) * | 2015-05-13 | 2018-09-05 | トヨタ自動車株式会社 | Exhaust gas purification catalyst and production method thereof |
| JP2022518113A (en) * | 2019-01-04 | 2022-03-14 | パシフィック インダストリアル デベロップメント コーポレイション | Nanocrystal-sized cerium-zirconium oxide material and its manufacturing method |
| WO2020159641A1 (en) * | 2019-01-29 | 2020-08-06 | Pacific Industrial Development Corporation | Nanocrystal-sized cerium-zirconium-aluminum oxide material and method of making the same |
| JP7443200B2 (en) * | 2020-09-03 | 2024-03-05 | 日本碍子株式会社 | porous ceramic structure |
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