CN101124045A - Process for producing metal oxide particle and exhaust gas purifying catalyst - Google Patents
Process for producing metal oxide particle and exhaust gas purifying catalyst Download PDFInfo
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- CN101124045A CN101124045A CNA2005800134240A CN200580013424A CN101124045A CN 101124045 A CN101124045 A CN 101124045A CN A2005800134240 A CNA2005800134240 A CN A2005800134240A CN 200580013424 A CN200580013424 A CN 200580013424A CN 101124045 A CN101124045 A CN 101124045A
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- colloidal particle
- bead
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- 239000002245 particle Substances 0.000 title claims abstract description 258
- 239000003054 catalyst Substances 0.000 title claims abstract description 92
- 229910044991 metal oxide Inorganic materials 0.000 title claims abstract description 85
- 150000004706 metal oxides Chemical class 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 56
- 239000000758 substrate Substances 0.000 claims description 94
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 68
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 68
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 64
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 48
- 238000000746 purification Methods 0.000 claims description 34
- 229910000510 noble metal Inorganic materials 0.000 claims description 29
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 28
- 230000004520 agglutination Effects 0.000 claims description 14
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 238000002485 combustion reaction Methods 0.000 claims description 10
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 8
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 8
- 239000004408 titanium dioxide Substances 0.000 claims description 8
- 238000001035 drying Methods 0.000 abstract description 31
- 239000000084 colloidal system Substances 0.000 abstract 7
- 230000004931 aggregating effect Effects 0.000 abstract 2
- 238000010304 firing Methods 0.000 abstract 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 122
- 230000006641 stabilisation Effects 0.000 description 44
- 230000000052 comparative effect Effects 0.000 description 40
- 239000007864 aqueous solution Substances 0.000 description 38
- 239000007789 gas Substances 0.000 description 37
- 229910052697 platinum Inorganic materials 0.000 description 34
- 238000003756 stirring Methods 0.000 description 27
- 239000003513 alkali Substances 0.000 description 26
- 239000000203 mixture Substances 0.000 description 26
- 206010013786 Dry skin Diseases 0.000 description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 18
- 239000012153 distilled water Substances 0.000 description 16
- 238000011156 evaluation Methods 0.000 description 15
- 239000000243 solution Substances 0.000 description 15
- 239000006185 dispersion Substances 0.000 description 13
- ZXVONLUNISGICL-UHFFFAOYSA-N 4,6-dinitro-o-cresol Chemical group CC1=CC([N+]([O-])=O)=CC([N+]([O-])=O)=C1O ZXVONLUNISGICL-UHFFFAOYSA-N 0.000 description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 12
- 239000001301 oxygen Substances 0.000 description 12
- 229910052760 oxygen Inorganic materials 0.000 description 12
- 230000000694 effects Effects 0.000 description 11
- 239000000463 material Substances 0.000 description 11
- 229910052684 Cerium Inorganic materials 0.000 description 10
- 238000005245 sintering Methods 0.000 description 10
- 229910052727 yttrium Inorganic materials 0.000 description 10
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 9
- 229910002091 carbon monoxide Inorganic materials 0.000 description 9
- 239000002912 waste gas Substances 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 7
- 235000011114 ammonium hydroxide Nutrition 0.000 description 7
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 7
- 229910017604 nitric acid Inorganic materials 0.000 description 7
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 6
- 229910010413 TiO 2 Inorganic materials 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 229910052726 zirconium Inorganic materials 0.000 description 6
- 239000002243 precursor Substances 0.000 description 5
- 239000010948 rhodium Substances 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- 229910052779 Neodymium Inorganic materials 0.000 description 4
- YRKCREAYFQTBPV-UHFFFAOYSA-N acetylacetone Chemical compound CC(=O)CC(C)=O YRKCREAYFQTBPV-UHFFFAOYSA-N 0.000 description 4
- 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 4
- 239000000446 fuel Substances 0.000 description 4
- 229930195733 hydrocarbon Natural products 0.000 description 4
- 150000002430 hydrocarbons Chemical class 0.000 description 4
- 239000002609 medium Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 4
- 229910052763 palladium Inorganic materials 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- 229910052703 rhodium Inorganic materials 0.000 description 4
- 229910002651 NO3 Inorganic materials 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- UJVRJBAUJYZFIX-UHFFFAOYSA-N nitric acid;oxozirconium Chemical compound [Zr]=O.O[N+]([O-])=O.O[N+]([O-])=O UJVRJBAUJYZFIX-UHFFFAOYSA-N 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- -1 zirconia Chemical compound 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 150000004703 alkoxides Chemical class 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000000975 co-precipitation Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000002612 dispersion medium Substances 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- CFYGEIAZMVFFDE-UHFFFAOYSA-N neodymium(3+);trinitrate Chemical compound [Nd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O CFYGEIAZMVFFDE-UHFFFAOYSA-N 0.000 description 2
- 239000011164 primary particle Substances 0.000 description 2
- 238000004445 quantitative analysis Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 2
- POILWHVDKZOXJZ-ARJAWSKDSA-M (z)-4-oxopent-2-en-2-olate Chemical compound C\C([O-])=C\C(C)=O POILWHVDKZOXJZ-ARJAWSKDSA-M 0.000 description 1
- 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 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229910017090 AlO 2 Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- DRVWBEJJZZTIGJ-UHFFFAOYSA-N cerium(3+);oxygen(2-) Chemical group [O-2].[O-2].[O-2].[Ce+3].[Ce+3] DRVWBEJJZZTIGJ-UHFFFAOYSA-N 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 238000002338 electrophoretic light scattering Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- QBHQQYMEDGADCQ-UHFFFAOYSA-N oxozirconium(2+);dinitrate;dihydrate Chemical compound O.O.[Zr+2]=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O QBHQQYMEDGADCQ-UHFFFAOYSA-N 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Images
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- Inorganic Compounds Of Heavy Metals (AREA)
- Catalysts (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
The present invention provides an exhaust gas purifying catalyst and a process for producing a metal oxide particle comprising multiple species of metal oxides and capable of satisfactorily exerting the properties of respective metal oxides. A process of the present invention comprises providing a sol containing at least a population of first colloid particles and a population of second colloid particles differing in the isoelectric point with each other; adjusting the pH of the sol to be closer to the isoelectric point of the population of first colloid particles than to the isoelectric point of the population of second colloid particles, thereby aggregating the population of first colloid particles; adjusting the pH of the sol, thereby aggregating the population of second colloid particles onto the population of first colloid particles aggregated; and drying and firing the obtained aggregate.
Description
Technical field
The present invention relates to make the method for metal oxide particle, more specifically, the present invention relates to by adding the manufacture method that supported noble metal is preferably used as the metal oxide particle of exhaust gas purification catalyst.In addition, the present invention relates to be used for the exhaust gas purification catalyst of internal combustion engine.
Background technology
The internal combustion engine for example waste gas of automobile engine generation contains nitrogen oxide (NO
x), carbon monoxide (CO), hydrocarbon (HC) etc.By can oxidation CO and HC, simultaneously can reductive NO
xExhaust gas purification catalyst can remove these materials.As representational exhaust gas purification catalyst, known noble metal such as platinum (Pt), rhodium (Rh) and palladium (Pd) are carried on porous metal oxide carrier such as the gama-alumina and the three-way catalyst that obtains.
Metal oxide carrier can be formed by various materials, but in order to obtain big surface area, at present normally used is aluminium oxide (Al
2O
3).But in recent years,, proposed with the aluminium oxide combination or do not used multiple other material such as cerium oxide (CeO in combination with aluminium oxide for the chemical property of utilizing carrier promotes the purification of waste gas
2), zirconia (ZrO
2) and titanium dioxide (TiO
2).
For example, thereby strengthen the waste gas purification ability of three-way catalyst for the fluctuation that alleviates oxygen concentration in the waste gas, to have the carrier of the material of oxygen storage capacity (OSC) as exhaust gas purification catalyst, this material is stored oxygen when oxygen concentration is high in the waste gas, then discharges oxygen when oxygen concentration in the waste gas is low.Representative materials with OSC is a cerium oxide.
For carry out oxidation and the NO of CO and HC effectively by the activity of three-way catalyst
xReduction, the air-fuel ratio in the internal combustion engine must be chemically correct fuel (stoichiometric air-fuel ratio).Therefore, preferably alleviate the fluctuation of oxygen concentration in the waste gas, thereby oxygen concentration is remained near the chemically correct fuel, three-way catalyst can be brought into play the ability of its waste gas purification thus.In addition, have been found that according to recent research cerium oxide not only has OSC, and because of its to the noble metal strong compatibility of platinum particularly, thereby can prevent the particle growth (sintering) of load noble metal thereon.
Therefore, cerium oxide has the preferred property that uses in exhaust gas purification catalyst, but it can not satisfy hear resistance required in this type of purposes sometimes.Therefore, people have developed by forming cerium oxide and zirconic solid solution and have improved stable on heating method (for example seeing Japanese unexamined patent publication No. communique (disclosing) 10-194742 number and 6-279027 number).
In addition, Japanese unexamined patent publication No. communique (disclosing) discloses the cerium oxide base particle as catalyst carrier for 2004-74138 number, and wherein cerium oxide is rich in the outside of particle, and the internal oxidation cerium of particle is then poor.The document is stated, thereby the cerium oxide base particle is rich in the particle growth that cerium oxide has suppressed load noble metal thereon because of the particle outside, and because particle internal oxidation cerium is poor thereby provide very little oxygen to store and releasability.The manufacture method of this cerium oxide base particle has: with cerous nitrate aqueous solution dipping ZrO
2Powder or AlO
2Powder, and with the method for its roasting; Make ZrO
2Precursor is settled out from zirconyl nitrate solution, to wherein adding the cerous nitrate aqueous solution, makes CeO
2Precursor is deposited in ZrO
2On the precursor, then with the method for its roasting; With the alkoxide that makes cerium at ZrO
2Precursor or CeO
2Hydrolysis on the precursor, and with the method for its roasting.
Comprise multiple material and utilize under the situation of metal oxide carrier of its performance combination above-mentioned providing, multiple metal oxide particle can be mixed, if but so mix, may can not get the good combination of the performance of these metal oxides, because the metal oxide particle of combination all has large scale separately.
In addition, the colloidal sol that gets from multiple different colloidal particle mixing can obtain basic even metal oxide particle, but mixture may not obtain optimum efficiency uniformly.
For example, the composite metal oxide by cerium oxide and zirconia evenly being mixed gained is known to have good OSC and hear resistance, but can not make cerium oxide bring into play the performance that it prevents noble metal such as platinum sintering fully sometimes.Therefore that is, cerium oxide and zirconia all are present on this composite metal oxide surface, and a part of noble metal is carried on the zirconia part but not on the cerium oxide part, thereby can not prevent sintering.
Therefore, the invention provides the method for making metal oxide particle, this metal oxide particle comprises multiple metal oxide and can bring into play the performance of each metal oxide fully.
In addition, the invention provides exhaust gas purification catalyst, comprise and contain more ZrO by noble metal is carried on
2The center and contain more CeO
2The bead-type substrate on top layer on, it is because ZrO
2Thereby can bring into play the improved heat resistance effect, can bring into play simultaneously and prevent to be carried on CeO
2On the effect of noble metal sintering.
Summary of the invention
Of the present inventionly be used to make the method that comprises the metal oxide particle of forming different cores and top layer and comprise: the colloidal sol that contains the mutually different first colloidal particle group of isoelectric point and the second colloidal particle group at least is provided; The pH that regulates colloidal sol is to the isoelectric point of comparing with the second colloidal particle group's isoelectric point more near the first colloidal particle group, particularly be adjusted to scope near the first colloidal particle group's isoelectric point ± 1.0, the scope of more special ± 0.5 makes the first colloidal particle group agglutination thus; The pH that regulates colloidal sol is to the isoelectric point of comparing with the first colloidal particle group's isoelectric point more near the second colloidal particle group, particularly be adjusted to scope near the second colloidal particle group's isoelectric point ± 1.0, the scope of more special ± 0.5 makes the second colloidal particle group agglutination thus on the first colloidal particle group of aggegation; With with gained agglutination body drying and roasting.
The method according to this invention can obtain comprising the metal oxide particle on core and top layer, and described core contains the more component that is derived from the first colloidal particle group, and the more component that is derived from the second colloidal particle group is contained on described top layer.
In addition, the method according to this invention, the metal oxide particle that can obtain having any particle diameter and have the structure that comprises core and top layer.For example, the colloidal particle group who is used as raw material in practice has the average grain diameter of about 5nm, and then the average grain diameter by the metal oxide particle of the inventive method manufacturing can be no more than 50nm.Therefore, this metal oxide particle can have and for example is lower than 10 μ m, is lower than 5 μ m, is lower than 1 μ m, is lower than 500nm, is lower than 200nm, is lower than 100nm or is lower than the average grain diameter of 50nm.
For comprising the metal oxide on core and top layer, used herein term " contains more " about using based on the molar fraction of core and the top layer metal total mole number in separately.Therefore, for example " contain the more core that is derived from the first colloidal particle group's component " and be meant the molar fraction height of the molar fraction of the metal that constitutes this component in the core than same metal in the top layer.
Used herein term " colloidal particle " is meant and comprises and be scattered in the liquid, particularly be scattered in the metal oxide in the water or be bonded to the particle of the metal of oxygen, and when decentralized medium being removed and obtained during with the residue roasting metal oxide." colloidal particle " is generally understood as the diameter with 1～1000nm, particularly has 1～500nm diameter.For example, can obtain containing the colloidal sol that diameter is lower than 100nm or is lower than the colloidal particle of 50nm.
Used herein term " colloidal sol " is meant the dispersion that colloidal particle is scattered in gained in the liquid dispersion medium, is sometimes referred to as colloidal solution.Contained decentralized medium water normally in the colloidal sol, but if desired, also can contain organic dispersion medium such as pure and mild acetylacetone,2,4-pentanedione.
In another embodiment of the inventive method, change the pH of colloidal sol and make its isoelectric point of passing through the first colloidal particle group, thereby make the first colloidal particle group agglutination.
According to this embodiment, when the pH of colloidal sol passed through the first colloidal particle group's isoelectric point, therefore the first colloidal particle group's zeta current potential vanishing, can make the first colloidal particle group agglutination reliably.
In another embodiment of the inventive method, change the pH of colloidal sol and make its isoelectric point of passing through the second colloidal particle group, thereby make the second colloidal particle group agglutination.
According to this embodiment, when the pH of colloidal sol passed through the second colloidal particle group's isoelectric point, therefore the second colloidal particle group's zeta current potential vanishing can make the second colloidal particle group agglutination reliably.
In another embodiment of the inventive method, the first colloidal particle group and the second colloidal particle group are selected from aluminium oxide, cerium oxide, zirconia and colloidal tio 2 particle independently of one another.
In another embodiment of the inventive method, the first colloidal particle group is zirconia, aluminium oxide or titanium dioxide, particularly zirconia, and the second colloidal particle group is a cerium oxide.
According to this embodiment, can obtain comprising the metal oxide particle on core and top layer, described core contains more zirconia, aluminium oxide or titanium dioxide, and more cerium oxide is contained on described top layer.
When platinum being carried on this metal oxide particle, can realizing the good heat resistance that brings by zirconia, aluminium oxide or titanium dioxide, particularly zirconia, and rely on cerium oxide can realize preventing the effect of platinum sintering.
In the case, based on the total mole number of metal in the metal oxide particle, total molar fraction of cerium and zirconium, aluminium or titanium can be at least 85 moles of %, especially at least 90 moles of %, more particularly at least 95 moles of %.
Internal combustion engine of the present invention comprises bead-type substrate and load noble metal thereon with exhaust gas purification catalyst, and this bead-type substrate comprises and contains more zirconia (ZrO
2) core and contain more cerium oxide (CeO
2) the top layer, CeO in the bead-type substrate
2Content be 40～65 moles of %, 45～55 moles of % particularly.
According to exhaust gas purification catalyst of the present invention, in bead-type substrate, contain more ZrO
2Core have suitable volume, contain more CeO
2The top layer covered whole core, thereby form layer with suitable thickness.As a result, preferably bring into play by ZrO simultaneously
2And the improved heat resistance effect that causes and by CeO
2And cause prevent the noble metal sintering effect.
In an embodiment of exhaust gas purification catalyst of the present invention, the top layer comprises at least a among at least a element, particularly Y that are selected from the group of being made up of alkaline-earth metal and terres rares and the Nd.
According to this embodiment, CeO
2Lattice strain increase, make to become 4 and/or become 3 from 4 and become easy from 3 because of the Ce ionic valence condition that must betatopic causes.Therefore, the storage/release performance that has improved oxygen is OSC, and this helps to improve the performance of catalyst.
In an embodiment of exhaust gas purification catalyst of the present invention, core comprises at least a element, particularly Y that is selected from the group of being made up of alkaline-earth metal and terres rares.
According to this embodiment, the hear resistance of bead-type substrate is improved, but reason is not clear.
Description of drawings
Fig. 1 is the cross-sectional view of expression by the metal oxide particle of the inventive method manufacturing.
Fig. 2 is the cross-sectional view of expression carrier of the present invention and load noble metal thereon.
Fig. 3 is expression CeO
2The figure that concerns between content and the specific area.
Fig. 4 is expression CeO
2The figure that concerns between content and the Pt particle diameter.
Fig. 5 is expression CeO
2The figure of relation between content and the catalyst performance (HC-T50).
Fig. 6 adds the figure that concerns between element and the specific area for expression.
Fig. 7 adds the figure that concerns between element and the Pt particle diameter for expression.
Fig. 8 adds the figure of relation between element and the catalyst performance (OSC) for expression.
Fig. 9 adds the figure of relation between element and the catalyst performance (HC-T50) for expression.
The specific embodiment
The manufacture method of＜metal oxide particle 〉
The manufacture method of metal oxide particle of the present invention is described with reference to the accompanying drawings.
1. Fig. 1 is the cross-sectional view of expression by the metal oxide particle of the inventive method manufacturing.
As shown in fig. 1, according to the inventive method, can make and comprise and form the different cores 1 and the metal oxide particle on top layer 2.More specifically, the method according to this invention, in the colloidal sol that contains at least two groups of mutually different colloidal particles of isoelectric point, the aggegation of first colloidal particle group elder generation, the second colloidal particle group agglutination is around the first colloidal particle group subsequently, thereby produce the metal oxide particle that comprises core 1 and top layer 2, described core 1 mainly is made of the component that is derived from the first colloidal particle group, and described top layer 2 mainly is made of the component that is derived from the second colloidal particle group.
In illustrated metal oxide particle, core 1 and top layer 2 comprise separately many primary particles that are derived from the first colloidal particle group and the second colloidal particle group (1a, 2a).But, between each primary particle, can exist or can not have tangible border.In addition, the border between core 1 and the top layer 2 can be obvious, and this border can be used as the part that composition changes gradually and occurs.In addition, the boundary member between core 1 and the top layer 2 can be the mixture that is derived from the first colloidal particle group's component and is derived from the second colloidal particle group's component, its solid solution in particular.In Fig. 1, shown in top layer 2 seemingly discontinuous, but this top layer can be continuous.
For the metal oxide that constitutes the metal oxide particle by the inventive method manufacturing, can select any metal oxide, can select preferably to remain on the interior metal oxide of metal oxide particle core as first metal oxide, and select preferably to be exposed to the metal oxide on metal oxide particle top layer as second metal oxide.For example, first metal oxide is preferably zirconia, and second metal oxide is preferably cerium oxide.Zirconia has high-fire resistance, and cerium oxide can prevent the sintering of platinum when load has platinum.
When the top layer of metal oxide particle of the present invention or core contained zirconia or cerium oxide, then cerium (Ce) and zirconium (Zr) metal in addition can be contained in core or top layer, for example are selected from the metal in the group of being made up of alkaline-earth metal and rare earth element, particularly yttrium (Y).These alkaline-earth metal and rare earth element, particularly yttrium, tending to provides good hear resistance to zirconia and cerium oxide.
With noble metal for example platinum, rhodium and palladium be carried on the metal oxide particle that makes by the inventive method, thereby can produce exhaust gas purification catalyst.In the exhaust gas purification catalyst of manufacturing because the prepared metal oxide particle of the inventive method can have core and top layer, but thereby the noble metal basic load on the top layer.
Can noble metal be loaded on the metal oxide particle, for example by any known method: use and contain the salt of noble metal and/or the solution impregnation metal oxide particle of complex salt, and the dry method of roasting then.The amount that is carried on the noble metal on the metal oxide can be 0.01～5 quality %, particularly 0.1～2 quality % based on metal oxide particle.
This exhaust gas purification catalyst both can use by this catalyst self is shaped, and also can for example use on the ceramic honeycomb body by it being coated on monolith substrate.
The following describes each step of the inventive method.
＜provide collosol intermixture 〉
In the methods of the invention, provide the colloidal sol that comprises the mutually different first colloidal particle group of isoelectric point and the second colloidal particle group at least.
The instantiation of prepared colloidal sol comprises by the material that alkoxide, acetylacetonate, acetate or nitrate are hydrolyzed and condensation obtains with metal.In addition, be well known materials such as the colloidal sol of alumina sol, zirconia sol, TiO 2 sol and cerium oxide sol, also can be used as the commercially available prod and obtain.
The pH that general commercially available metal oxide sol has is inequality with the isoelectric point of its interior contained colloidal particle, thus the Coulomb repulsion and prevent aggegation mutually of contained colloidal particle.That is to say, contain isoelectric point at the colloidal sol of the colloidal particle of an alkaline side by with colloidal sol acidifying stabilisation (colloidal sol of sour stabilisation), and contain isoelectric point at the colloidal sol of the colloidal particle of an acid side by with the colloidal sol alkalization and stabilisation (colloidal sol of alkali stabilisation).
The material that the isoelectric point of colloidal particle may not depend on constituent particle for example oxide self is fixed, can set arbitrarily by the surface modification to colloidal particle, particularly with organic compound colloidal particle is carried out surface modification.Therefore, the first colloidal particle group and the second colloidal particle group used in the inventive method can select arbitrarily separately, make it have the pH of the present invention of being fit to.For example, can select, make the isoelectric point difference of each group colloidal particle be not less than 3, particularly be not less than 4, more especially be not less than 5 the first colloidal particle group and the second colloidal particle group.
The isoelectric point of the colloidal particle that must know for the inventive method can be determined by any means.For example, can measure isoelectric point by the electrophoretic light scattering method.
The inventive method can with, the colloidal sol that contains two groups of colloidal particles at least can obtain by any means, but can obtain this colloidal sol by different colloidal sols are mixed especially.Can these colloidal particles group's mixed proportion be carried out determining arbitrarily according to the desired performance of metal oxide particle.
In the methods of the invention, preferably be contained in the element within the metal oxide particle such as alkaline-earth metal and terres rares, not only can be used as colloidal particle and also can be used as slaine for example nitrate be contained in the colloidal sol.
＜the first colloidal particle group's aggegation 〉
Then, in the methods of the invention, the pH that regulates colloidal sol is to the isoelectric point of comparing with the second colloidal particle group's isoelectric point more near the first colloidal particle group, thereby makes the first colloidal particle group agglutination.
As mentioned above, the pH that general commercially available metal oxide sol has is away from the isoelectric point of contained colloidal particle wherein, thereby can make the mutual Coulomb repulsion of colloidal particle and prevent its aggegation.Therefore, when the pH of the colloidal sol that will contain the first colloidal particle group and the second colloidal particle group changes near the isoelectric point of the first colloidal particle group among the present invention, the first colloidal particle group's zeta current potential diminishes, it is very little that this makes that the electricity that produces between the particle repels, and promoted the first colloidal particle group's aggegation thus.In this stage, the pH of colloidal sol relatively is different from the second colloidal particle group's isoelectric point, and therefore the second colloidal particle group has bigger zeta current potential, has prevented its aggegation thus.
Can regulate the pH of colloidal sol by adding acid arbitrarily or alkali.The example of operable acid comprises inorganic acid such as nitric acid and hydrochloric acid, and the example of operable alkali comprises ammoniacal liquor and NaOH.Also can only regulate the pH of colloidal sol by mixing multiple colloidal sol.
Can regulate the pH of colloidal sol by the following method: the method that in colloidal sol, adds acid or alkali when measuring colloidal sol pH with pH meter; Perhaps use in advance the colloidal sol of sampling to pre-determine pH and regulate necessary acid or alkali number, and the acid of scheduled volume or alkali are added to method in the whole colloidal sol.
＜the second colloidal particle group's aggegation 〉
Then, in the methods of the invention, the pH that regulates colloidal sol is to the isoelectric point of comparing with the first colloidal particle group's isoelectric point more near the second colloidal particle group, thereby makes the second colloidal particle group agglutination around the first colloidal particle group of aggegation.
When the pH of the colloidal sol that will contain the first colloidal particle group of aggegation so changes near the second colloidal particle group's the isoelectric point, the second colloidal particle group's zeta current potential diminishes, it is very little that this makes that the electricity that produces between the particle repels, and promoted the second colloidal particle group's aggegation thus.Therefore in this stage, the pH of colloidal sol relatively is different from the first colloidal particle group's isoelectric point, can prevent the first colloidal particle group's aggegation, and can make the second colloidal particle group be deposited on the first colloidal particle group around.
The pH of colloidal sol can regulate in the mode identical with the aggegation of above-mentioned first metal oxide.
The drying of＜agglutinator and roasting 〉
Dry and the roasting with the agglutinator of gained like this, thus can be made into the metal oxide particle that comprises core and top layer, described core mainly is made of the component that is derived from the first colloidal particle group, and described top layer mainly is made of the component that is derived from the second colloidal particle group.
Can under arbitrary temp, from colloidal sol, remove decentralized medium and dry by any means.For example, this can realize by colloidal sol being placed in 120 ℃ the baking oven.To can obtain metal oxide particle thus by from colloidal sol, removing the material calcination of decentralized medium and dry gained.Can for example carry out roasting under 500～1100 ℃ the temperature in the temperature that is generally used for making metal oxide.
＜exhaust gas purification catalyst 〉
As shown in Figure 2, aspect exhaust gas purification catalyst of the present invention best, constitute the CeO on the top layer 12 of bead-type substrate
2Cover by ZrO with suitable thickness
2The whole core 22 that forms, and noble metal 13 (Pt) is carried on the bead-type substrate.In addition, bead-type substrate preferably has little particle diameter.Verified, comprise that the exhaust gas purification catalyst of this bead-type substrate and load noble metal 3 thereon has good exhaust-gas purifying performance.Bead-type substrate is being coated in the integral catalyzer that obtains on the honeycomb substrates, is producing identical effect.
Can make used bead-type substrate in the exhaust gas purification catalyst of the present invention by being used to make the inventive method that comprises the metal oxide particle of forming different cores and top layer.
In the manufacture method of used bead-type substrate, the preferred employing comprises the CeO that particle diameter is as far as possible little in exhaust gas purification catalyst of the present invention
2And ZrO
2The CeO of colloidal particle
2And ZrO
2Colloidal sol, thus make the gained bead-type substrate have little particle diameter.The more little then specific area of the particle diameter of bead-type substrate is big more.In addition, preferably the noble metal that will be carried on the bead-type substrate is controlled at small particle diameter, thereby increases its specific area.
The increase of the specific area of bead-type substrate make can load noble metal amount can increase, even if use the bead-type substrate of identical weight.The increase of the specific area of noble metal makes can increase the area of the noble metal that contacts with waste gas, even if use the noble metal of identical weight.The increase of above-mentioned specific area can improve exhaust-gas purifying performance, even if the bead-type substrate and the noble metal of less amount is used in combination.
Can be by being scattered in bead-type substrate in the distilled water and adding precious metal solution, stir then, drying is gone forward side by side an one-step baking, and noble metal is carried on the bead-type substrate.Want the noble metal of load to be preferably to be selected from least a in the group of forming by Pt, Pd, Rh, Ir and Au, more preferably be selected from least a in the group of forming by Pt, Pd and Rh, most preferably Pt.
Hereinafter illustrate in greater detail the present invention, but the present invention is not limited to this with reference to embodiment.
＜embodiment 1～6 and comparative example 1～4 〉
In following test, use pH meter to measure the pH of colloidal sol, wherein pH meter electrode direct impregnation is gone in the colloidal sol.
＜embodiment 1 〉
In this embodiment, obtain comprising the metal oxide particle that contains more zirconic core and contain the top layer of more cerium oxide by the zirconia hydrosol of alkali stabilisation and the cerium oxide hydrosol of sour stabilisation.
With the zirconia hydrosol of alkali stabilisation (isoelectric point: pH3.5) and the cerium oxide hydrosol of sour stabilisation (isoelectric point: pH8.5) mix, make zirconia (ZrO
2) and cerium oxide (CeO
2) between mol ratio be 1: 1.When stirring, in this mixed sols, drip nitric acid (HNO
3) aqueous solution, pH is adjusted to 3.0, thereby makes the zirconia aggegation.Then when stirring, dropping ammonia (NH in this mixed sols
3) solution, pH is adjusted to 10, thereby makes the cerium oxide aggegation.
With the gained mixed sols in 120 ℃ of dryings 24 hours, and with desciccate in 700 ℃ of roastings 5 hours, obtain metal oxide particle.
＜embodiment 2 〉
In this embodiment, obtain comprising core that contains more titanium dioxide and the metal oxide particle that contains the top layer of more cerium oxide by the titania hydrosol of alkali stabilisation and the cerium oxide hydrosol of sour stabilisation.
With the titania hydrosol of alkali stabilisation (isoelectric point: pH3.9) and the cerium oxide hydrosol of sour stabilisation (isoelectric point: pH8.5) mix, make titanium dioxide (TiO
2) and cerium oxide (CeO
2) between mol ratio be 1: 1.When stirring, in this mixed sols, drip aqueous solution of nitric acid, pH is adjusted to 3.0, thereby makes the titanium dioxide aggegation.When stirring, dropping ammonia solution is adjusted to 10 with pH in this mixed sols, thereby makes the cerium oxide aggegation then.Subsequently, dry and roasting obtains metal oxide particle in the mode identical with embodiment 1.
＜embodiment 3 〉
In this embodiment, obtain comprising core that contains more aluminium oxide and the metal oxide particle that contains the top layer of more cerium oxide by the alumina hydrosol of alkali stabilisation and the cerium oxide hydrosol of sour stabilisation.
With the alumina hydrosol of alkali stabilisation (isoelectric point: pH4.8) and the cerium oxide hydrosol of sour stabilisation (isoelectric point: pH8.5) mix, make aluminium oxide (Al
2O
3) and cerium oxide (CeO
2) between mol ratio be 1: 2.When stirring, in this mixed sols, drip aqueous solution of nitric acid, pH is adjusted to 3.0, thereby makes the aluminium oxide aggegation.When stirring, dropping ammonia solution is adjusted to 10 with pH in this mixed sols, thereby makes the cerium oxide aggegation then.Subsequently, dry and roasting obtains metal oxide particle in the mode identical with embodiment 1.
＜embodiment 4 〉
In this embodiment, obtain comprising the metal oxide particle that contains more zirconic core and contain the top layer of more cerium oxide by the zirconia hydrosol of sour stabilisation and the cerium oxide hydrosol of alkali stabilisation.
With the zirconia hydrosol of sour stabilisation (isoelectric point: pH7.8) and the cerium oxide hydrosol of alkali stabilisation (isoelectric point: pH4.0) mix, make zirconia (ZrO
2) and cerium oxide (CeO
2) between mol ratio be 1: 1.When stirring, dropping ammonia solution is adjusted to 10 with pH in this mixed sols, thereby makes the zirconia aggegation.When stirring, in this mixed sols, drip aqueous solution of nitric acid then, pH is adjusted to 3.0, thereby makes the cerium oxide aggegation.Carry out drying and roasting in the mode identical subsequently, obtain metal oxide particle with embodiment 1.
＜embodiment 5 〉
In this embodiment, obtain comprising core that contains more titanium dioxide and the metal oxide particle that contains the top layer of more cerium oxide by the titania hydrosol of sour stabilisation and the cerium oxide hydrosol of alkali stabilisation.
With the titania hydrosol of sour stabilisation (isoelectric point: pH7.9) and the cerium oxide hydrosol of alkali stabilisation (isoelectric point: pH4.0) mix, make titanium dioxide (TiO
2) and cerium oxide (CeO
2) between mol ratio be 1: 1.When stirring, dropping ammonia solution is adjusted to 10 with pH in this mixed sols, thereby makes the titanium dioxide aggegation.When stirring, in this mixed sols, drip aqueous solution of nitric acid then, pH is adjusted to 3.0, thereby makes the cerium oxide aggegation.Carry out drying and roasting in the mode identical subsequently, obtain metal oxide particle with embodiment 1.
＜embodiment 6 〉
In this embodiment, obtain comprising core that contains more aluminium oxide and the metal oxide particle that contains the top layer of more cerium oxide by the alumina hydrosol of sour stabilisation and the cerium oxide hydrosol of alkali stabilisation.
With the alumina hydrosol of sour stabilisation (isoelectric point: pH7.6) and the cerium oxide hydrosol of alkali stabilisation (isoelectric point: pH4.0) mix, make aluminium oxide (Al
2O
3) and cerium oxide (CeO
2) between mol ratio be 1: 2.When stirring, dropping ammonia solution is adjusted to 10 with pH in this mixed sols, thereby makes the aluminium oxide aggegation.When stirring, in this mixed sols, drip aqueous solution of nitric acid then, pH is adjusted to 3.0, thereby makes the cerium oxide aggegation.Carry out drying and roasting in the mode identical subsequently, obtain metal oxide particle with embodiment 1.
＜comparative example 1 〉
In this embodiment, Zirconia particles and cerium oxide particles are mixed.
Zirconia particles and cerium oxide particles are mixed, make zirconia (ZrO
2) and cerium oxide (CeO
2) between mol ratio be 1: 1, and the particle that mixes was mixed in ball mill 100 hours.
＜comparative example 2 〉
In this embodiment, TiO 2 particles and cerium oxide particles are mixed.
TiO 2 particles and cerium oxide particles are mixed, make titanium dioxide (TiO
2) and cerium oxide (CeO
2) between mol ratio be 1: 1, and the particle that mixes was mixed in ball mill 100 hours.
＜comparative example 3 〉
In this embodiment, aluminium oxide particles and cerium oxide particles are mixed.
Aluminium oxide particles and cerium oxide particles are mixed, make aluminium oxide (Al
2O
3) and cerium oxide (CeO
2) between mol ratio be 1: 2, and the particle that mixes was mixed in ball mill 100 hours.
＜comparative example 4 〉
In this comparative example, adopt coprecipitation to obtain comprising the metal oxide particle of zirconia and cerium oxide.
Ammonium ceric nitrate and zirconyl nitrate dihydrate are added in the distilled water, and making the mol ratio between zirconium (Zr) and the cerium (Ce) is 1: 1.Dropping ammonia solution in this mixture causes precipitation thereby pH is adjusted to 9.Subsequently, carry out drying and roasting, obtain metal oxide particle in the mode identical with embodiment 1.
＜to the evaluation of metal oxide particle structure 〉
Adopt XPS (x-ray photoelectron beam split) quantitative analysis, to the surface C eO of gained metal oxide particle in embodiment 1～6 and the comparative example 1～4
2Concentration is measured.The result is as shown in table 1 below.
Table 1: surface C eO
2The XPS quantitative analysis of concentration
| Metal oxide particle | Quantitative values (atom %) | |
| |
Surface C eO 2-center ZrO 2Particle surface CeO 2-center TiO 2Particle surface CeO 2-center Al 2O 3Particle surface CeO 2-center ZrO 2Particle surface CeO 2-center TiO 2Particle surface CeO 2-center Al 2O 3Particle | 56％ 51％ 53％ 51％ 49％ 47％ |
| Comparative example 1 comparative example 2 comparative examples 3 comparative examples 4 | CeO 2Particle+ZrO 2Particle CeO 2Particle+TiO 2Particle CeO 2Particle+Al 2O 3Particle (Ce, Zr) O xParticle | 38％ 37％ 32％ 38％ |
Can obviously find out from table 1, than comparative example 1～3 that cerium oxide particles is mixed with Zirconia particles etc. and the comparative example 4 that obtains cerium oxide-Zirconia particles by co-precipitation, in metal oxide particle obtained by the method for the present invention, have than relatively large cerium oxide to be exposed to the surface, although the molar ratio between raw materials used is identical.
＜embodiment 7～10 and comparative example 5～8 〉
In following example, check CeO
2And ZrO
2Optimum content.At used CeO
2And ZrO
2CeO in the colloidal sol
2And ZrO
2Colloidal particle all has the particle diameter that is no more than 100nm.The particle diameter of the bead-type substrate of manufacturing is for being no more than 6 μ m.The Pt particle diameter of institute's load is for being no more than 3nm.
＜embodiment 7 〉
The catalyst of embodiment 7 comprises Pt (1 weight %) and comprises by CeO
2The top layer that constitutes with by ZrO
2The bead-type substrate of the core that constitutes, bead-type substrate consist of CeO
2: ZrO
2=60: 40 (mole %).Scoring item is specific area, Pt particle diameter, HC-T50 and OSC.By the catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %) and the ZrO of alkali stabilisation content:
2Colloidal sol (isoelectric point: pH3.5, ZrO
2Content: 10.2 weight %) mix, obtain CeO
2: ZrO
2Ratio is the collosol intermixture of 60: 40 (mole %).In this collosol intermixture, add HNO
3The aqueous solution transfers to 3.0 with pH, adds NH then
3The aqueous solution transfers to 11.0 with pH.Gained solution was 120 ℃ of dryings 24 hours, and desciccate obtains bead-type substrate 700 ℃ of roastings 5 hours.
Gained bead-type substrate like this is dispersed in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜embodiment 8 〉
The catalyst of embodiment 8 comprises Pt (1 weight %) and comprises by CeO
2And Y
2O
3The top layer that constitutes with by ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate consist of CeO
2: ZrO
2: Y
2O
3=45: 52: 3 (mole %).Scoring item is specific area, Pt particle diameter and HC-T50.Y adds as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the ZrO of alkali stabilisation content:
2Colloidal sol (isoelectric point: pH3.5, ZrO
210.2 weight %) and Y content:
2O
3Colloidal sol (Y
2O
3Content: 15 weight %) mix, obtain CeO
2: ZrO
2: Y
2O
3Ratio is the collosol intermixture of 45: 52: 3 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜embodiment 9 〉
The catalyst of embodiment 9 comprises Pt (1 weight %) and comprises by CeO
2And Y
2O
3The top layer that constitutes with by ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate consist of CeO
2: ZrO
2: Y
2O
3=50: 47: 3 (mole %).Scoring item is specific area, Pt particle diameter and HC-T50.Y adds as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the ZrO of alkali stabilisation content:
2Colloidal sol (isoelectric point: pH3.5, ZrO
210.2 weight %) and Y content:
2O
3Colloidal sol (Y
2O
3Content: 15 weight %) mix, obtain CeO
2: ZrO
2: Y
2O
3Ratio is the collosol intermixture of 50: 47: 3 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜embodiment 10 〉
The catalyst of embodiment 10 comprises Pt (1 weight %) and comprises by CeO
2And Y
2O
3The top layer that constitutes with by ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate consist of CeO
2: ZrO
2: Y
2O
3=55: 42: 3 (mole %).Scoring item is specific area, Pt particle diameter and HC-T50.Y adds as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the ZrO of alkali stabilisation content:
2Colloidal sol (isoelectric point: pH3.5, ZrO
210.2 weight %) and Y content:
2O
3Colloidal sol (Y
2O
3Content: 15 weight %) mix, obtain CeO
2: ZrO
2: Y
2O
3Ratio is the collosol intermixture of 55: 42: 3 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜comparative example 5 〉
The catalyst of comparative example 5 comprises Pt (1 weight %) and by ZrO
2The bead-type substrate that constitutes, this bead-type substrate is only by ZrO
2Powder constitutes.Scoring item is specific area, Pt particle diameter and HC-T50.By this catalyst that obtains as follows.
With ZrO
2Powder is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and with dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜comparative example 6 〉
The catalyst of comparative example 6 comprises Pt (1 weight %) and comprises by CeO
2And Y
2O
3The top layer that constitutes with by ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate has consists of CeO
2: ZrO
2: Y
2O
3=25: 72: 3 (mole %).Scoring item is specific area, Pt particle diameter and HC-T50.Y adds as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the ZrO of alkali stabilisation content:
2Colloidal sol (isoelectric point: pH3.5, ZrO
210.2 weight %) and Y content:
2O
3Colloidal sol (Y
2O
3Content: 15 weight %) mix, obtain CeO
2: ZrO
2: Y
2O
3Ratio is the collosol intermixture of 25: 72: 3 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜comparative example 7 〉
The catalyst of comparative example 7 comprises Pt (1 weight %) and comprises by CeO
2And Y
2O
3The top layer that constitutes with by ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate has consists of CeO
2: ZrO
2: Y
2O
3=75: 22: 3 (mole %).Scoring item is specific area, Pt particle diameter and HC-T50.Y adds as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the ZrO of alkali stabilisation content:
2Colloidal sol (isoelectric point: pH3.5, ZrO
210.2 weight %) and Y content:
2O
3Colloidal sol (Y
2O
3Content: 15 weight %) mix, obtain CeO
2: ZrO
2: Y
2O
3Ratio is the collosol intermixture of 75: 22: 3 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜comparative example 8 〉
The catalyst of comparative example 8 comprises Pt (1 weight %) and by CeO
2The bead-type substrate that constitutes, this bead-type substrate is only by CeO
2Powder constitutes.Scoring item is specific area, Pt particle diameter and HC-T50.By this catalyst that obtains as follows.
With CeO
2Powder is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and with dispersions obtained stirring 1 hour.After this removed moisture in 24 hours in 120 ℃ of dryings, residue was in 500 ℃ of roastings 2 hours.With the gained shaped catalyst is square granular of 1mm, and is used for performance evaluation.
＜estimate
Gained is configured as the square granular exhaust gas purification catalyst of 1mm carries out endurancing, will have rich gas and the lean gas formed shown in the table 2 separately and pass through above-mentioned catalyst 5 hours at 1000 ℃ in this endurancing, per 60 seconds with these gases switchings.Before being estimated, whole embodiment and comparative example all carry out this endurancing.
Table 2: the composition of gas
| N 2(％) | CO 2(％) | NO(ppm) | CO(％) | C 3H 6(ppmC) *1 | H 2(％) | O 2(％) | H 2O(％) | ||
| | Surplus | 10 | 2200 | 2.80 | 2500 | 0.27 | 0.77 | 10 | |
| | Surplus | 10 | 2200 | 0.81 | 2500 | 0.00 | 1.70 | 10 |
*1: only based on the concentration of carbon amount
Afterwards, make the rich gas and the lean gas that have table 2 composition separately pass through above-mentioned catalyst, under 1Hz, these gases are switched, improve gas temperature simultaneously, thereby determine 50%C in the gas
3H
6Temperature when being purified (HC-T50) by catalyst.In addition, make CO (2%) and O
2(1%) by catalyst, switched in per 60 minutes, by O
2Walk the CO that produces in the process
2Amount is calculated OSC (oxygen storage capacity) (O
2Mole/CeO
2-1 mole of %).
By BET one point method measurement the specific area (SSA), and at-80 ℃ by CO pulse determination of adsorption method Pt particle diameter.
The evaluation result of embodiment 7～10 and comparative example 5～8 is shown among table 3 and Fig. 3-5.CeO has been shown in the table 3
2Content, SSA (specific area), Pt particle diameter and the HC-T50 that indicates as catalyst performance.In addition, among Fig. 3 CeO has been shown
2Relation between content and the SSA has illustrated CeO among Fig. 4
2Relation between content and the Pt particle diameter has illustrated CeO among Fig. 5
2Relation between content and the HC-T50.
Table 3:CeO
2And ZrO
2The quantitative change result
| CeO 2Amount (mole %) | SSA *1(m 2/g) | Pt particle diameter (nm) | HC-T50(℃) | |
| Embodiment 7 | 60 | 18 | 15 | 287 |
| Embodiment 8 | 45 | 26 | 9 | 255 |
| Embodiment 9 | 50 | 25 | 9 | 256 |
| |
55 | 23 | 8 | 258 |
| Comparative example 5 | 0 | 28 | 53 | 301 |
| Comparative example 6 | 25 | 25 | 46 | 297 |
| Comparative example 7 | 75 | 12 | 17 | 289 |
| Comparative example 8 | 100 | 9 | 21 | 291 |
*1: the specific area that adopts the BET one point method to measure
Annotate: do not contain Y among the embodiment 7
2O
3, its composition is different from other embodiment, so its gained data are not shown in Fig. 3～5.
The bead-type substrate of embodiment 7 is only by CeO
2And ZrO
2Constitute, and the bead-type substrate of embodiment 8～10 and comparative example 5～8 comprises by CeO respectively
2And ZrO
2Add Y
2O
3The top layer and the core that constitute.Thereby the data of embodiment 7 can not be compared with other data simply, so the result of embodiment 7 is not shown in Fig. 3～5.
Can obviously find out from result shown in the table 3, although embodiment 7 does not add Y
2O
3, its HC-T50 still is lower than comparative example.Can obviously find out in addition, add Y
2O
3Increased specific area and reduced Pt particle diameter and HC-T50, promptly all scoring items all improve.
Can obviously find out the CeO in bead-type substrate from Fig. 4 and result shown in Figure 5
2When content is 40～65 moles of %, by ZrO
2And the improved heat resistance effect that causes and by CeO
2And the effect that prevents the noble metal sintering that causes preferably is achieved simultaneously, and by CeO
2OSC is improved, thereby obtain being suitable for the premium properties of exhaust gas purification catalyst.Can obviously find out from result shown in Figure 5, when containing 3 moles of %Y
2O
3Bead-type substrate have the CeO of 45～55 moles of %
2During content, then HC-T50 is minimum and the gained catalyst performance is good.
＜embodiment 11～12 and comparative example 9～10 〉
The effect of element is added in check below.Employed CeO
2And ZrO
2CeO in the colloidal sol
2And ZrO
2Colloidal particle all has the particle diameter that is no more than 100nm.The particle diameter of gained bead-type substrate is for being no more than 5 μ m.The particle diameter of the Pt of institute's load is for being no more than 3nm.
＜embodiment 11 〉
The catalyst of embodiment 11 comprises Pt (1 weight %) and comprises by CeO
2, Nd
2O
3And Y
2O
3The top layer that constitutes with by ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate has consists of CeO
2: ZrO
2: Y
2O
3: Nd
2O
3=58: 38: 2: 2 (mole %).Scoring item is specific area, Pt particle diameter, HC-T50 and OSC.Y and Nd add as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the Y of alkali stabilisation content:
2O
3-ZrO
2Complex sol (Y
2O
3Content: 5 weight %, complex sol content: 10.2 weight %) and neodymium nitrate mix, obtain CeO
2: ZrO
2: Y
2O
3: Nd
2O
3Ratio is 58: 38: 2: the collosol intermixture of 2 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.Removed moisture in 24 hours in 120 ℃ of dryings then, the gained residue was in 500 ℃ of roastings 2 hours.With the shaped catalyst that obtains is square granular of 1mm, and is used for performance evaluation.
＜embodiment 12 〉
The catalyst of embodiment 12 comprises Pt (1 weight %) and comprises by CeO
2And Y
2O
3The top layer that constitutes with by CeO
2, ZrO
2And Y
2O
3The bead-type substrate of the core that constitutes, bead-type substrate has consists of CeO
2: ZrO
2: Y
2O
3=58: 38: 4 (mole %).Scoring item is specific area, Pt particle diameter, HC-T50 and OSC.Y adds as oxide.By this catalyst that obtains as follows.
CeO with sour stabilisation
2Colloidal sol (isoelectric point: pH8.5, CeO
215 weight %), the Y of alkali stabilisation content:
2O
3-ZrO
2Complex sol (Y
2O
310.2 weight %) and Y content: 5 weight %, complex sol content:
2O
3Colloidal sol (Y
2O
3Content: 15 weight %) mix, obtain CeO
2: ZrO
2: Y
2O
3Ratio is the collosol intermixture of 58: 38: 4 (mole %).In this collosol intermixture, add HNO
3The aqueous solution is adjusted to 3.0 with pH, adds NH then
3The aqueous solution is adjusted to 11.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.Removed moisture in 24 hours in 120 ℃ of dryings then, residue was in 500 ℃ of roastings 2 hours.With the shaped catalyst that obtains is square granular of 1mm, and is used for performance evaluation.
＜comparative example 9 〉
The catalyst of comparative example 9 comprises Pt (1 weight %) and by CeO
2, ZrO
2With Nd
2O
3The bead-type substrate that constitutes, bead-type substrate has consists of CeO
2: ZrO
2: Nd
2O
3=58: 38: 4 (mole %).Scoring item is specific area, Pt particle diameter, HC-T50 and OSC.Nd adds as oxide.By this catalyst that obtains as follows.
Add cerous nitrate, zirconyl nitrate and neodymium nitrate in distilled water, stirring and dissolving obtains Ce: Zr: the Nd ratio is the mixture of 58: 38: 4 (mole %).In this mixture, add NH
3The aqueous solution is adjusted to 9.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.Removed moisture in 24 hours in 120 ℃ of dryings then, the gained residue was in 500 ℃ of roastings 2 hours.With the shaped catalyst that obtains is square granular of 1mm, and is used for performance evaluation.
＜comparative example 10 〉
The catalyst of comparative example 10 comprises Pt (1 weight %) and by CeO
2, ZrO
2With Y
2O
3The bead-type substrate that constitutes, bead-type substrate has consists of CeO
2: ZrO
2: Y
2O
3=58: 38: 4 (mole %).Scoring item is specific area, Pt particle diameter, HC-T50 and OSC.Y adds as oxide.By this catalyst that obtains as follows.
Add cerous nitrate, zirconyl nitrate and yttrium nitrate in distilled water, stirring and dissolving obtains Ce: Zr: the Y ratio is the mixture of 58: 38: 4 (mole %).In this mixture, add NH
3The aqueous solution is adjusted to 9.0 with pH.With gained solution 120 ℃ of dryings 24 hours, and with desciccate 700 ℃ of roastings 5 hours, obtain bead-type substrate.
The bead-type substrate that so obtains is scattered in the distilled water of 6 times of weight, to wherein adding the dinitro two ammino platinum aqueous solution (Pt content: 4.4 weight %), make that the platinum amount based on bead-type substrate is 1 weight %, and dispersions obtained stirring 1 hour.Removed moisture in 24 hours in 120 ℃ of dryings then, the gained residue was in 500 ℃ of roastings 2 hours.With the shaped catalyst that obtains is square granular of 1mm, and is used for performance evaluation.
＜estimate
By above-mentioned evaluation method to embodiment 7～10 and comparative example 5～8 to embodiment 7,11 and 12 and the catalyst of comparative example 9 and 10 estimate.Gained the results are shown in table 4 and Fig. 6～9.The HC-T50 that SSA (specific area), Pt particle diameter, OSC has been shown in the table 4 and has indicated as catalyst performance.In addition, relation between carrier structure and interpolation element and the SSA variation has been shown among Fig. 6, relation between carrier structure and interpolation element and the Pt change of size has been shown among Fig. 7, relation between carrier structure and interpolation element and the OSC variation has been shown among Fig. 8, the relation between carrier structure and interpolation element and the HC-T50 variation has been shown among Fig. 9.
Table 4
| Form | SSA *1(m 2/g) | Pt particle diameter (nm) | OSC(O 2mol/Ce mol) | HC-T50(℃) | |
| Embodiment 11 | Top layer (Ce, Nd, Y) O
x-core (Zr, Y) |
27 | 7 | 1.2 | 251 |
| Embodiment 12 | Top layer (Ce, Y) O
x-core (Zr, Y) |
28 | 9 | 1.0 | 255 |
| With reference to (embodiment 7) | Top layer CeO
2- |
18 | 15 | 0.5 | 287 |
| Comparative example 9 | (Ce，Zr，Nd) |
25 | 17 | 1.2 | 281 |
| Comparative example 10 | (Ce，Zr，Y) |
27 | 16 | 1.2 | 283 |
*1: the specific area that adopts the BET one point method to measure
At first analyze the result of embodiment 7,11 and 12.The bead-type substrate of embodiment 12 is with Y
2O
3Add the top layer of embodiment 1 bead-type substrate and the bead-type substrate that core obtains to.Compare with embodiment 1, further prevented the sintering of Pt among the embodiment 12, and the Pt particle diameter is reduced to and is no more than 10nm, and further improved OSC, therefore the HC-T50 as the catalyst performance indication is further reduced.In embodiment 11, Y
2O
3Be added to the top layer and the core of bead-type substrate, and further added Nd in the top layer
2O
3Compare with embodiment 12, Nd is added in conduct in embodiment 11
2O
3The result, the Pt particle diameter reduces, OSC improves, thereby further reduces as the HC-T50 of catalyst performance indication.Can obviously find out from the above description, with Y
2O
3And Nd
2O
3Add to exhaust gas purification catalyst carrier the top layer and with Y
2O
3When being added to the core of carrier of exhaust gas purification catalyst, catalyst performance is more good.Except that Y and Nd,, can realize identical effect by adding alkaline-earth metal such as Mg, Ca, Sr and Ba and rare earth element such as La, Pr, Sm, Eu and Gd.
Then to embodiment 11 and 12 and the result of comparative example 9 and 10 analyze.Although the difference of OSC unconfirmed, the top layer of embodiment 11 and 12 bead-type substrate is by CeO
2Constitute, thereby prevented the sintering of Pt and made the Pt particle diameter be no more than 10nm.As a result, the HC-T50 as the catalyst performance indication reduces.Thereby can find out obviously that for exhaust gas purification catalyst, compare with the carrier that only is made of the complex of multiple oxide, at high temperature performance is more good to adopt the catalyst that the carrier that comprises top layer and core obtains.
Claims (11)
1. method of making metal oxide particle, this metal oxide particle comprise forms different core and top layer, and described method comprises:
At least the colloidal sol that contains the mutually different first colloidal particle group of isoelectric point and the second colloidal particle group is provided,
The pH that regulates described colloidal sol extremely compares the more approaching described first colloidal particle group's isoelectric point with the described second colloidal particle group's isoelectric point, thereby makes the described first colloidal particle group agglutination,
The pH that regulates described colloidal sol is to comparing the more approaching described second colloidal particle group's isoelectric point with the described first colloidal particle group's isoelectric point, thus make the described second colloidal particle group agglutination to the described first colloidal particle group of aggegation and
Dry and the roasting with the gained agglutinator.
2. the process of claim 1 wherein that the pH that changes described colloidal sol makes its isoelectric point by the described first colloidal particle group, makes the described first colloidal particle group agglutination thus.
3. according to the method for claim 1 or 2, the pH that wherein changes described colloidal sol makes its isoelectric point by the described second colloidal particle group, makes the described second colloidal particle group agglutination thus.
4. each method of claim 1～3, wherein said first colloidal particle group and the described second colloidal particle group are selected from the group of being made up of aluminium oxide, cerium oxide, zirconia and colloidal tio 2 particle independently of one another.
5. the method for claim 4, the wherein said first colloidal particle group is zirconia, aluminium oxide or titanium dioxide, the described second colloidal particle group is a cerium oxide.
6. exhaust gas purification catalyst that is used for internal combustion engine, it comprises bead-type substrate and load noble metal thereon, this bead-type substrate comprises and contains more zirconia (ZrO
2) core and contain more cerium oxide (CeO
2) the top layer, CeO in the bead-type substrate
2Content be 40～65 moles of %.
7. the exhaust gas purification catalyst that is used for internal combustion engine of claim 6, wherein CeO in the bead-type substrate
2Content be 45～55 moles of %.
8. claim 6 or 7 the exhaust gas purification catalyst that is used for internal combustion engine, its mesexine comprises at least a element that is selected from the group of being made up of alkaline-earth metal and terres rares.
9. the exhaust gas purification catalyst that is used for internal combustion engine of claim 8 wherein is contained in element in the top layer and is at least a among Y and the Nd.
10. claim 6 or 7 the exhaust gas purification catalyst that is used for internal combustion engine, wherein core comprises at least a element that is selected from the group of being made up of alkaline-earth metal and terres rares.
11. the exhaust gas purification catalyst that is used for internal combustion engine of claim 10, the element that wherein is contained in core is Y.
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| JP131433/2004 | 2004-04-27 | ||
| JP2004131637A JP4123185B2 (en) | 2004-04-27 | 2004-04-27 | Method for producing metal oxide particles |
| JP131637/2004 | 2004-04-27 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102781840A (en) * | 2010-03-01 | 2012-11-14 | 第一稀元素化学工业株式会社 | Cerium oxide-zirconium oxide composite oxide and method for producing the same |
| CN102099111B (en) * | 2008-07-16 | 2013-07-10 | 日产自动车株式会社 | Exhaust gas purifying catalyst and method for producing the same |
| CN107213887A (en) * | 2017-07-10 | 2017-09-29 | 中自环保科技股份有限公司 | Functional material and preparation method thereof |
| CN109399703A (en) * | 2013-09-23 | 2019-03-01 | 亨斯迈P & A英国有限公司 | Titanium dioxide granule and its manufacturing method |
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| JP4179299B2 (en) | 2005-03-23 | 2008-11-12 | トヨタ自動車株式会社 | Catalyst carrier powder and exhaust gas purification catalyst |
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| JP5465842B2 (en) * | 2008-05-23 | 2014-04-09 | トヨタ自動車株式会社 | Core-shell structure and exhaust gas-purifying catalyst including the core-shell structure |
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| JP2013129056A (en) * | 2011-11-21 | 2013-07-04 | Tosoh Corp | Zirconia composite powder for polishing and method for producing the same |
| JP2013203640A (en) * | 2012-03-29 | 2013-10-07 | Admatechs Co Ltd | Method for producing complex oxide powder |
| JP2013203639A (en) * | 2012-03-29 | 2013-10-07 | Admatechs Co Ltd | Complex oxide powder |
-
2004
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102099111B (en) * | 2008-07-16 | 2013-07-10 | 日产自动车株式会社 | Exhaust gas purifying catalyst and method for producing the same |
| CN102781840A (en) * | 2010-03-01 | 2012-11-14 | 第一稀元素化学工业株式会社 | Cerium oxide-zirconium oxide composite oxide and method for producing the same |
| US8765631B2 (en) | 2010-03-01 | 2014-07-01 | Daiichi Kigenso Kagaku Kogyo Co., Ltd. | Cerium oxide-zirconium oxide composite oxide and method for producing the same |
| CN102781840B (en) * | 2010-03-01 | 2015-04-22 | 第一稀元素化学工业株式会社 | Cerium oxide-zirconium oxide composite oxide and method for producing the same |
| CN109399703A (en) * | 2013-09-23 | 2019-03-01 | 亨斯迈P & A英国有限公司 | Titanium dioxide granule and its manufacturing method |
| CN107213887A (en) * | 2017-07-10 | 2017-09-29 | 中自环保科技股份有限公司 | Functional material and preparation method thereof |
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