JP4450763B2 - Precious metal-containing composite metal oxide for exhaust gas purification catalyst and method for producing the same - Google Patents
Precious metal-containing composite metal oxide for exhaust gas purification catalyst and method for producing the same Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims description 88
- 150000004706 metal oxides Chemical class 0.000 title claims description 56
- 229910044991 metal oxide Inorganic materials 0.000 title claims description 52
- 239000003054 catalyst Substances 0.000 title claims description 51
- 238000000746 purification Methods 0.000 title claims description 31
- 238000004519 manufacturing process Methods 0.000 title claims description 22
- 239000010970 precious metal Substances 0.000 title description 8
- 229910000510 noble metal Inorganic materials 0.000 claims description 88
- 239000011148 porous material Substances 0.000 claims description 45
- 150000001875 compounds Chemical class 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 21
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 238000010304 firing Methods 0.000 claims description 14
- 150000002736 metal compounds Chemical class 0.000 claims description 14
- 150000002910 rare earth metals Chemical class 0.000 claims description 14
- 229910052684 Cerium Inorganic materials 0.000 claims description 12
- QRTRRDMHGTZPBF-UHFFFAOYSA-L oxygen(2-);zirconium(4+);sulfate Chemical compound [O-2].[Zr+4].[O-]S([O-])(=O)=O QRTRRDMHGTZPBF-UHFFFAOYSA-L 0.000 claims description 12
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 11
- 239000003513 alkali Substances 0.000 claims description 11
- 229910052726 zirconium Inorganic materials 0.000 claims description 11
- 239000002994 raw material Substances 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 150000004692 metal hydroxides Chemical class 0.000 claims description 6
- 150000003609 titanium compounds Chemical class 0.000 claims description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 238000009826 distribution Methods 0.000 claims description 5
- 239000002244 precipitate Substances 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910003455 mixed metal oxide Inorganic materials 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 2
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 claims 1
- 239000000243 solution Substances 0.000 description 29
- 239000007789 gas Substances 0.000 description 27
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 20
- 229910052751 metal Inorganic materials 0.000 description 17
- 239000002184 metal Substances 0.000 description 17
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 14
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 238000006386 neutralization reaction Methods 0.000 description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 9
- 239000012535 impurity Substances 0.000 description 9
- 229910052763 palladium Inorganic materials 0.000 description 9
- 229910052697 platinum Inorganic materials 0.000 description 8
- 229910052727 yttrium Inorganic materials 0.000 description 8
- 229910002651 NO3 Inorganic materials 0.000 description 7
- 229910000420 cerium oxide Inorganic materials 0.000 description 7
- 229910052703 rhodium Inorganic materials 0.000 description 7
- 239000010948 rhodium Substances 0.000 description 7
- 238000011109 contamination Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- 150000002823 nitrates Chemical class 0.000 description 6
- 229910052779 Neodymium Inorganic materials 0.000 description 5
- 150000001242 acetic acid derivatives Chemical class 0.000 description 5
- 150000003842 bromide salts Chemical class 0.000 description 5
- 238000001354 calcination Methods 0.000 description 5
- 150000001805 chlorine compounds Chemical class 0.000 description 5
- 238000000975 co-precipitation Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 229910052746 lanthanum Inorganic materials 0.000 description 5
- 229910017604 nitric acid Inorganic materials 0.000 description 5
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 5
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- 229910001928 zirconium oxide Inorganic materials 0.000 description 5
- 229910052692 Dysprosium Inorganic materials 0.000 description 4
- 229910052691 Erbium Inorganic materials 0.000 description 4
- 229910052693 Europium Inorganic materials 0.000 description 4
- 229910052688 Gadolinium Inorganic materials 0.000 description 4
- 229910052689 Holmium Inorganic materials 0.000 description 4
- 229910052765 Lutetium Inorganic materials 0.000 description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 229910052772 Samarium Inorganic materials 0.000 description 4
- 229910052771 Terbium Inorganic materials 0.000 description 4
- 229910052775 Thulium Inorganic materials 0.000 description 4
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 4
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 4
- -1 cerium carbonate compound Chemical class 0.000 description 4
- 150000004679 hydroxides Chemical class 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 235000011121 sodium hydroxide Nutrition 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000008033 biological extinction Effects 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 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 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000000843 powder Substances 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
- 238000005245 sintering Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 150000000703 Cerium Chemical class 0.000 description 1
- 229910021193 La 2 O 3 Inorganic materials 0.000 description 1
- 229910017493 Nd 2 O 3 Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 150000001447 alkali salts Chemical class 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- RCFVMJKOEJFGTM-UHFFFAOYSA-N cerium zirconium Chemical compound [Zr].[Ce] RCFVMJKOEJFGTM-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012456 homogeneous solution Substances 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 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 1
- 239000002905 metal composite material Substances 0.000 description 1
- 238000006140 methanolysis reaction Methods 0.000 description 1
- 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 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 150000002941 palladium compounds Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000002468 redox effect Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 150000003754 zirconium Chemical class 0.000 description 1
- 150000003755 zirconium compounds Chemical class 0.000 description 1
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Description
本発明は、排ガス浄化触媒用貴金属含有複合金属酸化物及びその製造方法に関する。 The present invention relates to a noble metal-containing composite metal oxide for an exhaust gas purification catalyst and a method for producing the same.
自動車等の内燃機関から排出される排気ガス中の炭化水素、一酸化炭素及び窒素酸化物を同時に除去できる三元触媒においては、触媒活性成分として白金、ロジウム、パラジウム等の白金族元素とともに、触媒担体としての機能とその触媒活性を向上させるために、酸化還元特性をもつ酸化セリウムが酸化ジルコニウムとの複合金属酸化物として用いられている。ところが、白金族元素と酸化セリウム及び酸化ジルコニウムとの複合金属酸化物を含む触媒では、１０００℃以上の高温下での特性、例えば、酸化還元特性等が著しく低下するため、その触媒性能が劣化しやすいことが知られている。
このため、最近では、高温で焼成した場合に焼成前と比較して比表面積の減少度合いの少ない（比表面積の耐熱性が良い）もの、又は、全気孔容量の減少度合いの少ない（全気孔容量の耐熱性が良い）ものが求められるようになってきている。
なお、以下、本発明において、触媒とは、触媒担体及び助触媒の概念も含むものとして取り扱うものとする。In a three-way catalyst that can simultaneously remove hydrocarbons, carbon monoxide, and nitrogen oxides in exhaust gas discharged from an internal combustion engine such as an automobile, the catalyst is combined with a platinum group element such as platinum, rhodium, and palladium as a catalyst active component. In order to improve the function as a support and its catalytic activity, cerium oxide having redox properties is used as a composite metal oxide with zirconium oxide. However, in a catalyst containing a composite metal oxide of a platinum group element and cerium oxide and zirconium oxide, characteristics at a high temperature of 1000 ° C. or higher, such as oxidation-reduction characteristics, are remarkably lowered, so that the catalyst performance deteriorates. It is known to be easy.
Therefore, recently, when calcined at a high temperature, the degree of reduction in specific surface area is smaller than that before firing (the heat resistance of the specific surface area is good), or the degree of reduction in total pore volume is small (total pore volume) (Heat resistance is good).
Hereinafter, in the present invention, the catalyst is treated as including the concept of a catalyst carrier and a promoter.
特許文献１には、「（ａ）ジルコニア、（ｂ）イットリウムおよびカルシウムのうち少なくとも一種および（ｃ）希土類元素（但し、イットリウムおよびセリウムを除く）のうち少くとも一種を含有してなる安定化されたセリウム酸化物（Ｉ）と、活性アルミナ（ＩＩ）と、ロジウムおよび白金およびパラジウムよりなる群から選ばれた少なくとも一種の白金族金属（ＩＩＩ）とを含有してなり、該安定化セリウム酸化物（Ｉ）はセリアとして１０〜５０重量％、該イットリウムおよびカルシウムのうち少くとも一種の酸化物（ｂ）は０．１〜１５重量％、かつ該希土類元素（イットリウム、セリウムを除く）のうちの少くとも一種以上の酸化物（ｃ）は０．１〜１５重量％の範囲で含有されてなる触媒組成物を、ハニカム構造を有するモノリス担体に被覆せしめてなる排ガス浄化用触媒」が記載されているが、白金族金属は含浸法により坦持されており、又、高温での特性を十分満足するものではない。
又、特許文献２には、「超臨界流体に溶解させた金属化合物の溶液を、多孔質の消失性基体に含浸させ、次いで前記金属化合物を含浸した前記消失性基体を加熱することを特徴とする触媒担体の製造方法。」及び「白金、金、パラジウム、ロジウム、ルテニウム、及びイリジウムからなる群より選択された少なくとも１種の元素を含む貴金属化合物を超臨界流体に溶解させ、触媒担体に前記超臨界流体を含浸させ、前記貴金属化合物を含浸した前記触媒担体を加熱することを特徴とする触媒の製造方法。」が記載されているが、含浸方法に特徴があるものの、いまだ実用に供されているものではない。 Patent Document 2 states that “a solution of a metal compound dissolved in a supercritical fluid is impregnated into a porous extinction substrate, and then the extinction substrate impregnated with the metal compound is heated. And a precious metal compound containing at least one element selected from the group consisting of platinum, gold, palladium, rhodium, ruthenium and iridium in a supercritical fluid, and The catalyst manufacturing method is characterized by heating the catalyst carrier impregnated with a supercritical fluid and impregnated with the noble metal compound. Although the method is characterized in the impregnation method, it is still in practical use. It is not what you have.
更に、特許文献３には、「混合セリウムないしジルコニウム酸化物の製造方法にして、三価セリウムないしジルコニウム化合物を含有する液体混合物を調製し；該混合物を（ｉ）炭酸塩もしくは重炭酸塩及び（ｉｉ）塩基と反応間に反応性媒体のｐＨが中性又は塩基性のままであるような条件下に接触させ；炭酸セリウム化合物を含む沈殿物を収集し；該沈殿物を焼成する、各工程を含む方法。」及び「少なくとも０．６ｃｍ３／ｇの全気孔容量を有し、しかも全気孔容量の少なくとも５０％が１０〜１００ｎｍの直径を有する気孔からなる、混合セリウムないしジルコニウム酸化物。」が記載されているが、セリア含有量が７０％以上、すなわち、セリアリッチな混合セリウムないしジルコニウム酸化物に関するものであり、又、全気孔容量の耐熱性については何らの記載もない。Further, Patent Document 3 describes that “a liquid mixture containing a trivalent cerium or zirconium compound is prepared by a method for producing a mixed cerium or zirconium oxide; the mixture is prepared from (i) carbonate or bicarbonate and ( ii) contacting under conditions such that the pH of the reactive medium remains neutral or basic between the base and the reaction; collecting the precipitate containing the cerium carbonate compound; calcining the precipitate; And “a mixed cerium or zirconium oxide having a total pore volume of at least 0.6 cm 3 / g, and wherein at least 50% of the total pore volume consists of pores having a diameter of 10 to 100 nm.” Is related to mixed cerium or zirconium oxide having a ceria content of 70% or more, that is, ceria-rich, No no description about heat resistance amount.
一方、特許文献４には、「ジルコニウム及びセリウムを含む複合酸化物であって、（１）結晶相の９ ５体積％以上がジルコニア−セリア系固溶体の立方晶であり、かつ、（２）当該複合酸化物を１０００℃で熱処理した後に室温まで冷却する工程を２回以上繰り返した後でも、当該立方晶比率が７５体積％以上であることを特徴とするジルコニウム−セリウム系複合酸化物。」及び「塩基性硫酸ジルコニウムとセリウムイオンを含む溶液とを混合した後、当該混合液に塩基を添加し、ｐＨを１２以上１４未満とすることにより沈殿物を生成させることを特徴とするジルコニウム−セリウム系複合酸化物の製造方法。」が記載されている。
しかしながら、耐熱性は大幅に改善されているものの、全気孔容量に関する記載は一切ない。On the other hand, Patent Document 4 states that “a composite oxide containing zirconium and cerium, (1) 95% by volume or more of the crystal phase is a cubic crystal of a zirconia-ceria solid solution, and (2) A zirconium-cerium-based composite oxide, wherein the cubic ratio is 75% by volume or more even after the step of cooling the composite oxide to 1000 ° C. and then cooling to room temperature is repeated twice or more. “Zirconium-cerium system characterized in that a basic zirconium sulfate and a solution containing cerium ions are mixed, then a base is added to the mixture, and a precipitate is generated by adjusting the pH to 12 or more and less than 14. "Production method of composite oxide."
However, although the heat resistance is greatly improved, there is no description regarding the total pore volume.
一方、特許文献５には、「ＴｉＯ２、ＣｅＯ２、ＺｒＯ２及びＦｅ２Ｏ３のうちから選ばれた１種以上の金属酸化物Ａ、Ｔｉ、Ｃｅ、Ｚｒ及びＦｅのうちから選ばれた１種もしくは２種の金属の複合酸化物Ｂ、又は上記金属酸化物Ａと上記金属複合酸化物Ｂとの混合物Ｃのうちのいずれかを担体とし、この金属酸化物系担体にパラジウムが担持されていることを特徴とするメタノール分解用触媒の製造方法であって、上記金属酸化物系担体を形成するための金属の化合物とパラジウム化合物とを溶媒に溶かしてなる原料溶液を調製し、上記原料溶液とアルカリ溶液とを混合することによって、上記金属を上記金属酸化物系担体の前駆体である水酸化物等として沈澱させると同時に、該金属酸化物系担体の前駆体に上記パラジウムを水酸化物として共沈させることを特徴とするメタノール分解用触媒の製造方法。」が記載されている。
しかしながら、自動車排ガス触媒に関する記載又は示唆等は全くなく、又、当然のことながら、比表面積及び全気孔容量の耐熱性について何らの記載はない。On the other hand, in Patent Document 5, “selected from one or more metal oxides A, Ti, Ce, Zr and Fe selected from among TiO 2 , CeO 2 , ZrO 2 and Fe 2 O 3 . One of the composite oxide B of one or two metals or the mixture C of the metal oxide A and the metal composite oxide B is used as a carrier, and palladium is supported on the metal oxide carrier. A method for producing a catalyst for methanol decomposition, comprising: preparing a raw material solution obtained by dissolving a metal compound and a palladium compound for forming the metal oxide carrier in a solvent; By mixing a solution and an alkaline solution, the metal is precipitated as a hydroxide or the like that is a precursor of the metal oxide carrier, and at the same time, the palladium is added to the precursor of the metal oxide carrier. Process for preparing a catalyst for the methanolysis for causing coprecipitation as objects. "Is described.
However, there is no description or suggestion regarding the automobile exhaust gas catalyst, and of course, there is no description about the heat resistance of the specific surface area and the total pore volume.
本発明は上記の問題点に鑑み成されたものであって、その目的とするところは、全気孔容量の耐熱性に優れた排ガス浄化触媒用複合金属酸化物及びその製造方法を提供することにある。 The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a composite metal oxide for an exhaust gas purifying catalyst excellent in heat resistance of the total pore volume and a method for producing the same. is there.
本発明者等は、上記目的を達成するため鋭意研究した結果、特定の方法で、排ガス浄化触媒用複合金属酸化物に０．００１〜０．０３％の貴金属酸化物を含有させることにより、意外にも１０５０℃で２４時間焼成後の全気孔容量が０．２５ｃｃ／ｇ以上である全気孔容量の耐熱性に優れた排ガス浄化触媒用複合金属酸化物が得られることを見出した。
この知見に基づき本発明は、
（１）ジルコニウム、セリウム及び貴金属からなる貴金属含有複合酸化物において、（１）貴金属含有量が０．００１〜０．０３％であり、（２）１０５０℃で２４時間焼成後の全気孔容量が０．２５ｃｃ／ｇ以上であることを特徴とする排ガス浄化触媒用貴金属含有複合金属酸化物。
（２）ＢＪＨ法に基づく細孔分布において、５０〜９０ｎｍの気孔径にピークを有し、かつ、全気孔容量が０．６ｃｃ／ｇ以上であることを特徴とする前記（１）記載の排ガス浄化触媒用貴金属含有複合金属酸化物。
（３）１０〜１００ｎｍの直径を有する気孔の合計容積が全気孔容量の５０％以上を占めることを特徴とする前記（１）又は前記（２）に記載の排ガス浄化触媒用貴金属含有複合金属酸化物。
（４）希土類（Ｃｅを除く）、チタン及びアルミニウムから選ばれる１種以上の酸化物を含有することを特徴とする前記（１）〜前記（３）のいずれかに記載の排ガス浄化触媒用貴金属含有複合金属酸化物。
（５）ジルコニウム含有量が４０％以上であることを特徴とする前記（１）〜前記（４）のいずれかに記載の排ガス浄化触媒用貴金属含有複合金属酸化物。
（６）Ｚｒ化合物、Ｃｅ化合物及び貴金属化合物を溶媒に溶かしてなる原料溶液にアルカリを添加することにより、貴金属水酸化物との複合水酸化物を共沈させた後、これを焼成し、貴金属酸化物との複合酸化物を製造することを特徴とする前記（１）〜前記（５）のいずれかに記載の排ガス浄化触媒用貴金属含有複合金属酸化物の製造方法。
（７）原料溶液が、更に、希土類（Ｃｅを除く）化合物、チタン化合物及びアルミニウム化合物から選ばれる１種以上の化合物を含んでいることを特徴とする前記（６）記載の排ガス浄化触媒用貴金属含有複合金属酸化物の製造方法。
（８）Ｚｒ化合物として、水に不溶性の塩基性硫酸ジルコニウムを用いることを特徴とする前記（６）又は前記（７）に記載の排ガス浄化触媒用貴金属含有複合金属酸化物の製造方法。
（９）ＺｒＯ２とＣｅＯ２を分散させてなる原料溶液に貴金属化合物を溶かし、該溶液にアルカリを添加することにより、貴金属水酸化物を析出沈殿させた後、これを焼成し、貴金属酸化物との複合酸化物を製造することを特徴とする前記（１）〜前記（５）のいずれかに記載の排ガス浄化触媒用貴金属含有複合金属酸化物の製造方法。
（１０）原料溶液が、更に、希土類（Ｃｅを除く）酸化物、チタン酸化物及びアルミニウム酸化物から選ばれる１種以上の酸化物を含んでいることを特徴とする前記（９）記載の排ガス浄化触媒用貴金属含有複合金属酸化物の製造方法。
を提供するものである。
As a result of diligent research to achieve the above object, the present inventors have surprisingly included 0.001 to 0.03% of a noble metal oxide in a composite metal oxide for an exhaust gas purification catalyst by a specific method. In addition, it was found that a composite metal oxide for an exhaust gas purifying catalyst excellent in heat resistance of the total pore volume after firing at 1050 ° C. for 24 hours and having a total pore volume of 0.25 cc / g or more can be obtained.
Based on this finding, the present invention
(1) In a noble metal-containing composite oxide comprising zirconium, cerium and a noble metal, (1) the noble metal content is 0.001 to 0.03%, and (2) the total pore capacity after firing at 1050 ° C. for 24 hours. A noble metal-containing composite metal oxide for an exhaust gas purification catalyst, characterized by being 0.25 cc / g or more.
(2) The exhaust gas according to (1), wherein the pore distribution based on the BJH method has a peak in the pore diameter of 50 to 90 nm and the total pore volume is 0.6 cc / g or more. Precious metal-containing composite metal oxide for purification catalysts.
(3) The noble metal-containing composite metal oxidation for exhaust gas purification catalyst according to (1) or (2), wherein the total volume of pores having a diameter of 10 to 100 nm occupies 50% or more of the total pore volume object.
(4) The noble metal for exhaust gas purification catalyst according to any one of (1) to (3) above, which contains one or more oxides selected from rare earths (excluding Ce), titanium and aluminum Containing composite metal oxide.
(5) The noble metal-containing composite metal oxide for exhaust gas purification catalyst according to any one of (1) to (4) above, wherein the zirconium content is 40% or more.
(6) By adding alkali to a raw material solution obtained by dissolving a Zr compound, a Ce compound and a noble metal compound in a solvent, a composite hydroxide with a noble metal hydroxide is coprecipitated, and then calcined to obtain a noble metal. A method for producing a noble metal-containing composite metal oxide for exhaust gas purification catalyst according to any one of (1) to (5), wherein a composite oxide with an oxide is produced.
(7) The noble metal for exhaust gas purification catalyst according to (6), wherein the raw material solution further contains at least one compound selected from a rare earth (excluding Ce) compound, a titanium compound, and an aluminum compound. A method for producing a mixed metal oxide.
(8) The method for producing a noble metal-containing composite metal oxide for an exhaust gas purifying catalyst according to (6) or (7), wherein basic zirconium sulfate insoluble in water is used as the Zr compound .
(9) A noble metal compound is dissolved in a raw material solution in which ZrO 2 and CeO 2 are dispersed, and an alkali is added to the solution to precipitate and precipitate the noble metal hydroxide. The method for producing a noble metal-containing composite metal oxide for exhaust gas purification catalyst according to any one of (1) to (5), wherein the composite oxide is produced.
(10) The exhaust gas according to (9), wherein the raw material solution further contains one or more oxides selected from rare earth (excluding Ce) oxide, titanium oxide, and aluminum oxide. A method for producing a precious metal-containing composite metal oxide for a purification catalyst.
Is to provide.
本発明により、１０５０℃で２４時間焼成後の全気孔容量が０．２５ｃｃ／ｇ以上の耐熱性に優れた排ガス浄化触媒用貴金属含有複合金属酸化物が得られるため、斯界において好適に用いることが出来る。 According to the present invention, a noble metal-containing composite metal oxide for an exhaust gas purifying catalyst excellent in heat resistance having a total pore volume of 0.25 cc / g or more after calcination at 1050 ° C. for 24 hours can be obtained. I can do it.
以下に本発明の排ガス浄化触媒用貴金属含有複合金属酸化物について詳細に説明する。
先ず、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物は、ジルコニウム、セリウム及び貴金属からなる貴金属含有複合酸化物において、１０５０℃で２４時間焼成後の全気孔容量が０．２５ｃｃ／ｇ以上であることを特徴とする。
ジルコニウム及びセリウムからなる複合酸化物において、貴金属酸化物を触媒活性化成分としてではなく、単なる一成分として微量添加したところ、意外にも、全気孔容量及び１０５０℃で２４時間焼成後の全気孔容量が高いものが得られることを発見したところに本発明の最大の特徴がある。
この理由については、現在のところでは明確な理由は判っていないが、貴金属は、ジルコニア−セリア複合酸化物に複合化されず、高分散しているだけであるが、何らかのメカニズムでジルコニア−セリア複合酸化物の高温での焼結を防止しているものと考えられる。そして、この焼結防止効果は、結果として、触媒性能の劣化を抑制することができるという長所となっている。
なお、貴金属としては、Ｐｔ、Ｐｄ及びＲｈが例示される。The noble metal-containing composite metal oxide for exhaust gas purification catalyst of the present invention will be described in detail below.
First, the noble metal-containing composite metal oxide for an exhaust gas purification catalyst of the present invention is a noble metal-containing composite oxide composed of zirconium, cerium and a noble metal, and has a total pore volume of 0.25 cc / g or more after firing at 1050 ° C. for 24 hours. It is characterized by being.
In a complex oxide composed of zirconium and cerium, a noble metal oxide was added as a mere component rather than as a catalyst activating component. Surprisingly, the total pore volume and the total pore volume after firing for 24 hours at 1050 ° C. The greatest feature of the present invention is that it has been found that a high value can be obtained.
The reason for this is not clear at present, but the precious metal is not compounded into the zirconia-ceria composite oxide, but is only highly dispersed. It is considered that the oxide is prevented from sintering at a high temperature. And this sintering prevention effect has the advantage that deterioration of catalyst performance can be suppressed as a result.
In addition, as a noble metal, Pt, Pd, and Rh are illustrated.
次に、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物は、ＢＪＨ法に基づく細孔分布において、５０〜９０ｎｍの気孔径にピークを有し、かつ、全気孔容量が０．６ｃｃ／ｇ以上であることを特徴とする。
なお、全気孔容量と比表面積は密接な関係があり、全気孔容量が大きいということは、実質的に大きな比表面積を有することができるため、複合酸化物中に貴金属を高分散に坦持できるという長所がある。
更に、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物は、１０〜１００ｎｍの直径を有する気孔の合計容積が全気孔容量の５０％以上を占めることが好ましい。Next, the noble metal-containing composite metal oxide for exhaust gas purification catalyst of the present invention has a peak in the pore diameter of 50 to 90 nm in the pore distribution based on the BJH method, and the total pore volume is 0.6 cc / g. It is the above.
Note that the total pore volume and the specific surface area are closely related, and the fact that the total pore volume is large means that the noble metal can be supported in a highly dispersed state in the composite oxide because it can have a substantially large specific surface area. There is an advantage.
Furthermore, in the noble metal-containing composite metal oxide for exhaust gas purification catalyst of the present invention, the total volume of pores having a diameter of 10 to 100 nm preferably occupies 50% or more of the total pore volume.
なお、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物は、希土類（Ｃｅを除く）、チタン及びアルミニウムから選ばれる１種以上の酸化物を含有しても良い。
希土類（Ｃｅを除く）金属としては、Ｙ、Ｌａ、Ｎｄ、Ｐｒ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｌｕが例示され、この中で、Ｌａ、Ｎｄ、Ｐｒがジルコニア−セリア複合酸化物の比表面積を向上させることができるという理由で好ましい。
希土類（Ｃｅを除く）金属酸化物の含有量は、５〜３０％が好ましい。これは、ジルコニア−セリア複合酸化物の比表面積を向上させるための効果的な量であり、５％未満及び３０％を超える場合は、その効果が低下するという理由からである。The noble metal-containing composite metal oxide for exhaust gas purification catalyst of the present invention may contain one or more oxides selected from rare earths (excluding Ce), titanium, and aluminum.
Examples of rare earth (excluding Ce) metals include Y, La, Nd, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu. Among these, La, Nd, Pr Is preferable because the specific surface area of the zirconia-ceria composite oxide can be improved.
The content of rare earth (excluding Ce) metal oxide is preferably 5 to 30%. This is an effective amount for improving the specific surface area of the zirconia-ceria composite oxide, and when it is less than 5% or more than 30%, the effect is reduced.
一方、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物中のジルコニウム含有量は４０％以上、好ましくは５０％以上、特に好ましくは６０％以上である。
４０％未満では、単位セリア当りのＯＳＣ（酸素吸蔵容量）が低下するので好ましくない（本発明において、％は重量％を意味する）。
又、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物中の貴金属含有量は、０．００１〜１％、好ましくは０．００５〜０．５％、特に好ましくは０．０１〜０．０３である。０．００１％未満では、超微量となり、貴金属の添加効果がなくなり、１％を超えるとそれに見合う効果が得られず、また、コスト高となる。On the other hand, the zirconium content in the noble metal-containing composite metal oxide for exhaust gas purification catalyst of the present invention is 40% or more, preferably 50% or more, particularly preferably 60% or more.
If it is less than 40%, the OSC (oxygen storage capacity) per unit ceria is undesirably lowered (in the present invention,% means% by weight).
Further, the noble metal content in the noble metal-containing composite metal oxide for exhaust gas purification catalyst of the present invention is 0.001 to 1%, preferably 0.005 to 0.5%, particularly preferably 0.01 to 0.03. It is. If it is less than 0.001%, the amount is extremely small, and the effect of adding a noble metal is lost. If it exceeds 1%, an effect commensurate with it cannot be obtained, and the cost increases.
以下、本発明の排ガス浄化触媒用貴金属含有複合金属酸化物の製造方法の一例を記載するが、本発明はこれにより何ら制限を受けるものではない。
先ず、共沈法について説明する。
本発明において用いる▲１▼Ｚｒ化合物、▲２▼Ｃｅ化合物及び▲３▼貴金属化合物としては水溶性のものであれば特に限定されず、硝酸塩、硫酸塩、酢酸塩、塩化物、臭化物等が例示されるが、後工程での不純物の混入を避けるためには硝酸塩が好ましい。
なお、貴金属としては、Ｐｔ、Ｐｄ及びＲｈが例示される。
本発明において、上記の３化合物に加えて、更に、希土類（Ｃｅを除く）化合物、チタン化合物及びアルミニウム化合物から選ばれる１種以上の化合物を含有させることが出来る。希土類（Ｃｅを除く）金属としては、Ｙ、Ｌａ、Ｎｄ、Ｐｒ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｌｕが例示される。
希土類（Ｃｅを除く）化合物、チタン化合物及びアルミニウム化合物から選ばれる１種以上の化合物としては、水溶性のものであれば特に限定されず、硝酸塩、硫酸塩、酢酸塩、塩化物、臭化物等が例示されるが、後工程での不純物の混入を避けるためには硝酸塩が好ましい。Hereinafter, although an example of the manufacturing method of the noble metal containing composite metal oxide for exhaust gas purification catalysts of this invention is described, this invention does not receive a restriction | limiting at all by this.
First, the coprecipitation method will be described.
The (1) Zr compound, (2) Ce compound and (3) noble metal compound used in the present invention are not particularly limited as long as they are water-soluble, and examples thereof include nitrates, sulfates, acetates, chlorides and bromides. However, nitrate is preferred in order to avoid contamination of impurities in the subsequent process.
In addition, as a noble metal, Pt, Pd, and Rh are illustrated.
In the present invention, in addition to the above three compounds, one or more compounds selected from rare earth (excluding Ce) compounds, titanium compounds and aluminum compounds can be further contained. Examples of the rare earth metal (excluding Ce) include Y, La, Nd, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu.
One or more compounds selected from rare earth (excluding Ce) compounds, titanium compounds and aluminum compounds are not particularly limited as long as they are water-soluble, and nitrates, sulfates, acetates, chlorides, bromides, etc. Although illustrated, nitrate is preferable in order to avoid contamination of impurities in the post-process.
次に、所定の割合としたこれらの化合物（金属塩）を混合するが、混合溶液中の金属塩濃度は、酸化物換算で、１〜５％である。１重量％未満では濃度が薄いため、処理に時間がかかり、５重量％を超えると中和時の粘性上昇により攪拌が不十分となり、複合化されにくくなるので好ましくない。 Next, although these compounds (metal salt) made into the predetermined ratio are mixed, the metal salt density | concentration in a mixed solution is 1 to 5% in conversion of an oxide. If it is less than 1% by weight, the concentration is thin, so that the treatment takes time, and if it exceeds 5% by weight, stirring is insufficient due to an increase in viscosity during neutralization, and it is difficult to form a composite.
本発明で用いるアルカリとしては、苛性ソーダ、炭酸ソーダ等が好ましい。
アルカリの濃度も特に限定されないが、水で希釈し、通常５〜３０％のものが用いられる。
このようにして用意した金属塩溶液とアルカリ溶液を混合して、ｐＨを８．５〜１０とし、複合水酸化物を共沈させることにより、本発明の前駆体ともいえる貴金属含有複合水酸化物を得ることが出来る。なお、混合方法としては、▲１▼金属塩溶液にアルカリ溶液を添加する、▲２▼アルカリ溶液に金属塩溶液を添加する、の２つの方法があるが、特に限定されるものではなく、どちらの方法を用いても良い。
ｐＨが８．５未満では、添加された各種金属が十分に水酸化物として得られない可能性があり、１０を超えると添加されるＮａの量が多くなり、不純物として残存する。
中和後液を濾過することにより、貴金属含有複合水酸化物を得ることが出来る。この貴金属含有複合水酸化物は、必要に応じて、純水等で水洗することにより、不純物を除去することが好ましい。
この後、必要に応じ、乾燥等を行い、これを焼成処理することが出来る。As the alkali used in the present invention, caustic soda, sodium carbonate and the like are preferable.
The concentration of alkali is not particularly limited, but it is diluted with water and usually 5 to 30%.
By mixing the prepared metal salt solution and the alkali solution to adjust the pH to 8.5 to 10 and coprecipitating the composite hydroxide, the noble metal-containing composite hydroxide can be said to be a precursor of the present invention. Can be obtained. There are two methods of mixing: (1) adding an alkali solution to a metal salt solution, and (2) adding a metal salt solution to an alkali solution, but there is no particular limitation. The method may be used.
If the pH is less than 8.5, the various metals added may not be sufficiently obtained as hydroxides, and if it exceeds 10, the amount of Na added will increase and remain as impurities.
By filtering the solution after neutralization, a noble metal-containing composite hydroxide can be obtained. The noble metal-containing composite hydroxide is preferably washed with pure water or the like as necessary to remove impurities.
Thereafter, if necessary, drying or the like can be performed, and this can be fired.
最後に、このようにして製造した貴金属含有複合水酸化物を焼成することにより、貴金属含有複合金属酸化物を製造する。
焼成温度は、特に限定されないが、通常は５００〜８００℃程度で１Ｈｒ〜１０Ｈｒ行う。５００℃未満では十分な結晶化が進まず、８００℃を超えると、初期の比表面積が低くなるため好ましくない。なお、焼成雰囲気は、特に限定されないが、通常大気中又は酸化性雰囲気中とすれば良い。Finally, the noble metal-containing composite metal oxide is manufactured by firing the thus-prepared noble metal-containing composite hydroxide.
Although a calcination temperature is not specifically limited, Usually, 1Hr-10Hr are performed at about 500-800 degreeC. When the temperature is lower than 500 ° C., sufficient crystallization does not proceed. When the temperature exceeds 800 ° C., the initial specific surface area is lowered, which is not preferable. Although the firing atmosphere is not particularly limited, it may be usually in the air or an oxidizing atmosphere.
ところで、本発明において、上記のＺｒ化合物の替わりに、水に不溶性の塩基性硫酸ジルコニウムを用いることが好ましい。
塩基性硫酸ジルコニウムとしては、特に制限されず、例えばＺｒＯＳＯ４・ＺｒＯ２、５ＺｒＯ２・３ＳＯ３、７ＺｒＯ２・３ＳＯ３等で示される化合物の水和物が挙げられる。これらは１種又は２種以上で使用することができる。
一般に、これらの塩基性塩は、溶解度の小さい光学的測定による粒径が数十オングストロームの微粒子の凝集体として０．１〜十数μｍの粒径を有する凝集粒子として得られるものであり、公知の製法で得られたもの又は市販品を用いることができる。例えば、「Ｇｍｅｌｉｎ Ｈａｎｄｂｕｃｈ，ＴＥＩＬ ４２；Ｚｉｒｋｏｎｉｕｍ（ＩＳＢＮ３−５４０−９３２４２−９，３３４−３５３，１９５８）」等に記載されたものも使用できる。By the way, in the present invention, it is preferable to use basic zirconium sulfate insoluble in water instead of the above Zr compound.
The basic zirconium sulfate is not particularly limited, for example ZrOSO 4 · ZrO 2, 5ZrO 2 · 3SO 3, 7ZrO hydrates of the compounds represented by 2 · 3SO 3 and the like. These can be used alone or in combination of two or more.
Generally, these basic salts are obtained as aggregated particles having a particle size of 0.1 to several tens of μm as aggregates of fine particles having a particle size of several tens of angstroms as measured by optical measurement with low solubility. What was obtained by the manufacturing method of this, or a commercial item can be used. For example, what was described in "Gmelin Handbuch, TEIL 42; Zirkonium (ISBN3-540-93224-9,334-353,1958)" etc. can also be used.
以下、Ｚｒ化合物の替わりに、水に不溶性の塩基性硫酸ジルコニウムを用いた場合の、貴金属含有複合金属酸化物の製造方法について記載するが、本発明はこれにより何ら制限を受けるものではない。
先ず、塩基性硫酸ジルコニウムを分散させた溶液を作製する。この溶液中の塩基性硫酸ジルコニウムの濃度は、５％〜９％とすることが好ましい。
次に、本発明において用いるＣｅ化合物及び貴金属化合物としては水溶性のものであれば特に限定されず、硝酸塩、硫酸塩、酢酸塩、塩化物、臭化物等が例示されるが、後工程での不純物の混入を避けるためには硝酸塩が好ましい。
なお、貴金属としては、Ｐｔ、Ｐｄ及びＲｈが例示される。Hereinafter, a method for producing a noble metal-containing composite metal oxide in the case where basic zirconium sulfate insoluble in water is used instead of the Zr compound will be described, but the present invention is not limited thereby.
First, a solution in which basic zirconium sulfate is dispersed is prepared. The concentration of basic zirconium sulfate in this solution is preferably 5% to 9%.
Next, the Ce compound and the noble metal compound used in the present invention are not particularly limited as long as they are water-soluble, and examples thereof include nitrates, sulfates, acetates, chlorides, bromides, and the like. Nitrate is preferred to avoid contamination.
In addition, as a noble metal, Pt, Pd, and Rh are illustrated.
本発明において、上記の３化合物に加えて、更に、希土類（Ｃｅを除く）化合物、チタン化合物及びアルミニウム化合物から選ばれる１種以上の化合物を含有させることが出来る。希土類（Ｃｅを除く）金属としては、Ｙ、Ｌａ、Ｎｄ、Ｐｒ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｌｕが例示される。
希土類（Ｃｅを除く）化合物、チタン化合物及びアルミニウム化合物から選ばれる１種以上の化合物としては、水溶性のものであれば特に限定されず、硝酸塩、硫酸塩、酢酸塩、塩化物、臭化物等が例示されるが、後工程での不純物の混入を避けるためには硝酸塩が好ましい。
そして、所定の割合としたこれらの化合物（塩基性硫酸ジルコニウム及び金属塩）を混合するが、混合溶液中の金属塩濃度（不溶性の塩基性硫酸ジルコニウムも含む）は、酸化物換算で、２〜１０％、好ましくは４〜８％である。２％未満では濃度が薄いため、処理に時間がかかり、１０％を超えると中和時の粘性上昇により攪拌が不十分となり、複合化されにくくなるので好ましくない。In the present invention, in addition to the above three compounds, one or more compounds selected from rare earth (excluding Ce) compounds, titanium compounds and aluminum compounds can be further contained. Examples of the rare earth metal (excluding Ce) include Y, La, Nd, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu.
One or more compounds selected from rare earth (excluding Ce) compounds, titanium compounds and aluminum compounds are not particularly limited as long as they are water-soluble, and nitrates, sulfates, acetates, chlorides, bromides, etc. Although illustrated, nitrate is preferable in order to avoid contamination of impurities in the post-process.
And these compounds (basic zirconium sulfate and metal salt) made into the predetermined ratio are mixed, but the metal salt concentration (including insoluble basic zirconium sulfate) in the mixed solution is 2 to 2 in terms of oxide. 10%, preferably 4-8%. If the concentration is less than 2%, the concentration is thin, and thus the treatment takes time. If the concentration exceeds 10%, stirring is insufficient due to an increase in viscosity at the time of neutralization, which is not preferable because it is difficult to be combined.
次に、このようにして作製された混合用液を中和するが、これは以下のように３段階に分けて中和することが好ましい。
（１）一次中和
ここでは、塩基性硫酸ジルコニウム由来の硫酸根の除去及び水酸化物化と他の金属塩の水酸化物化を行うが、複合水酸化物中の硫酸根を極力排除するためには、特に限定されるものではないが、２０〜３０％のＮａＯＨを用いて、ｐＨ＝１２．５〜１３．５となるように中和することが好ましい。
ｐＨが１２．５未満では、硫酸根を完全に除去することが出来ず、１３．５を超えると経済的ではない。
中和が終了すれば、これをろ過・水洗することにより、複合水酸化物を得ることが出来るが、複合水酸化物中の不純物を除去するためには、十分な水洗を行うことが好ましい。
（２）二次中和
一次中和をｐＨ＝１２．５〜１３．５と強アルカリで行ったため、ここでは複合水酸化物に付着しているＮａ分を除去するために、特に限定されるものではないが、スラリー濃度を２％〜１０％とし、濃硝酸を用いて、ｐＨ＝７〜８となるように中和することが好ましい。
ｐＨが７未満では水酸化物が溶解する恐れがあり、又、ｐＨが８を超えるとＮａ分の除去が不十分となる可能性がある。
（３）三次中和
二次中和後にろ過・水洗を行うに当り、水洗時の水酸化物の溶出を防止するため、特に限定されるものではないが、予め、２５％のアンモニア水を用いて、ｐＨ＝９〜１０としておくことが好ましい。Next, the liquid for mixing thus prepared is neutralized, and this is preferably neutralized in three stages as follows.
(1) Primary neutralization Here, the sulfate radicals derived from basic zirconium sulfate are removed, and hydroxides and hydroxides of other metal salts are removed. In order to eliminate sulfate radicals in composite hydroxides as much as possible. Although there is no particular limitation, neutralization is preferably performed using 20 to 30% NaOH so that the pH is 12.5 to 13.5.
If the pH is less than 12.5, the sulfate radical cannot be completely removed, and if it exceeds 13.5, it is not economical.
When neutralization is completed, a composite hydroxide can be obtained by filtering and washing with water. However, in order to remove impurities in the composite hydroxide, it is preferable to perform sufficient water washing.
(2) Secondary neutralization Since the primary neutralization was carried out with a strong alkali at pH = 12.5 to 13.5, it is particularly limited here in order to remove Na adhering to the composite hydroxide. Although it is not a thing, it is preferable to neutralize so that a slurry density | concentration shall be 2-10%, and it may be set to pH = 7-8 using concentrated nitric acid.
If the pH is less than 7, the hydroxide may be dissolved. If the pH exceeds 8, the removal of Na may be insufficient.
(3) Tertiary neutralization While performing filtration and washing after secondary neutralization, there is no particular limitation in order to prevent hydroxide elution during washing, but 25% ammonia water is used in advance. Thus, it is preferable to set the pH to 9 to 10.
そして、三次中和が終わった貴金属含有複合水酸化物を含むスラリーを濾過することにより、貴金属含有複合水酸化物を得ることが出来る。この貴金属含有複合水酸化物は、必要に応じて、純水等で水洗することにより、不純物を除去することが好ましい。
この後、必要に応じ、乾燥等を行い、これを焼成処理することが出来る。
最後に、このようにして製造した貴金属含有複合水酸化物を焼成することにより、貴金属含有複合金属酸化物を製造する。
焼成温度は、特に限定されないが、通常は５００〜８００℃程度で１Ｈｒ〜１０Ｈｒ行う。５００℃未満では十分な結晶化が進まず、８００℃を超えると、初期の比表面積が低くなるため好ましくない。なお、焼成理雰囲気は、特に限定されないが、通常大気中又は酸化性雰囲気中とすれば良い。And the noble metal containing composite hydroxide can be obtained by filtering the slurry containing the noble metal containing composite hydroxide after the tertiary neutralization. The noble metal-containing composite hydroxide is preferably washed with pure water or the like as necessary to remove impurities.
Thereafter, if necessary, drying or the like can be performed, and this can be fired.
Finally, the noble metal-containing composite metal oxide is manufactured by firing the thus-prepared noble metal-containing composite hydroxide.
Although a calcination temperature is not specifically limited, Usually, 1Hr-10Hr are performed at about 500-800 degreeC. When the temperature is lower than 500 ° C., sufficient crystallization does not proceed. When the temperature exceeds 800 ° C., the initial specific surface area is lowered, which is not preferable. The firing atmosphere is not particularly limited, but may be usually in the air or in an oxidizing atmosphere.
次に、析出沈殿法について説明する。
先ず、ＺｒＯ２とＣｅＯ２の粉末を用意する。
なお、ジルコニウム塩とセリウム塩の混合用液を中和することにより、ジルコニウムとセリウムの混合水酸化物からなるものを用いても良いことは言うまでもない。
ＺｒＯ２とＣｅＯ２の粉末を酸性溶媒中に分散させる。酸性溶媒としては、硝酸、硫酸、酢酸、塩酸等を水で希釈したものが例示されるが、後工程での不純物の混入を避けるためには硝酸溶液が好ましい。
そして、この分散溶液中に貴金属化合物を溶解させる。貴金属化合物としては水溶性のものであれば特に限定されず、硝酸塩、硫酸塩、酢酸塩、塩化物、臭化物等が例示されるが、後工程での不純物の混入を避けるためには硝酸塩が好ましい。
なお、貴金属としては、Ｐｔ、Ｐｄ及びＲｈが例示される。Next, the precipitation method is described.
First, powders of ZrO 2 and CeO 2 are prepared.
Needless to say, a mixture of zirconium and cerium may be used by neutralizing the mixed solution of zirconium salt and cerium salt.
ZrO 2 and CeO 2 powders are dispersed in an acidic solvent. Examples of the acidic solvent include those obtained by diluting nitric acid, sulfuric acid, acetic acid, hydrochloric acid and the like with water, but a nitric acid solution is preferable in order to avoid contamination of impurities in the subsequent steps.
And a noble metal compound is dissolved in this dispersion solution. The noble metal compound is not particularly limited as long as it is water-soluble, and examples thereof include nitrates, sulfates, acetates, chlorides, bromides, etc., but nitrates are preferable in order to avoid contamination of impurities in the subsequent steps. .
In addition, as a noble metal, Pt, Pd, and Rh are illustrated.
本発明において、上記のＺｒＯ２とＣｅＯ２及び貴金属化合物に加えて、更に、希土類（Ｃｅを除く）、チタン及びアルミニウムから選ばれる１種以上の酸化物を含有させることが出来る。希土類（Ｃｅを除く）金属としては、Ｙ、Ｌａ、Ｎｄ、Ｐｒ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｌｕが例示される。
なお、ＺｒＯ２とＣｅＯ２と同様に予め水酸化物として添加しておいても良い。In the present invention, in addition to the ZrO 2 , CeO 2 and the noble metal compound, one or more oxides selected from rare earths (excluding Ce), titanium and aluminum can be further contained. Examples of the rare earth metal (excluding Ce) include Y, La, Nd, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu.
Incidentally, it may be added in advance as the hydroxide in the same manner as ZrO 2 and CeO 2.
次に、これらの混合液にアルカリを添加することにより、貴金属水酸化物をＺｒＯ２とＣｅＯ２上に析出沈殿させることにより、貴金属水酸化物含有複合酸化物を得ることが出来る。これをろ過・水洗し、焼成することにより、貴金属含有複合金属酸化物を製造することが出来る。
なお、詳細な条件等については、上記の共沈法とほぼ同様である。Next, a noble metal hydroxide-containing composite oxide can be obtained by adding an alkali to these mixed solutions to precipitate the noble metal hydroxide on ZrO 2 and CeO 2 . A precious metal-containing composite metal oxide can be produced by filtering, washing with water and firing.
In addition, about detailed conditions etc., it is substantially the same as said coprecipitation method.
本発明は、上記の製造法の一例として示した共沈法又は析出沈殿法で作製された貴金属含有複合金属酸化物も包含するものである。
すなわち、ジルコニウム、セリウム及び貴金属からなる貴金属含有複合酸化物において、該貴金属含有複合酸化物が共沈法又は析出沈殿法により製造されたものであることを特徴とするもの、更に、希土類（Ｃｅを除く）、チタン及びアルミニウムから選ばれる１種以上の酸化物を含んでいることを特徴とする排ガス浄化触媒用貴金属含有複合金属酸化物を包含する。The present invention also includes a noble metal-containing composite metal oxide produced by the coprecipitation method or the precipitation method shown as an example of the above production method.
That is, a noble metal-containing composite oxide composed of zirconium, cerium and a noble metal, wherein the noble metal-containing composite oxide is produced by a coprecipitation method or a precipitation method, and further, a rare earth (Ce And a noble metal-containing composite metal oxide for an exhaust gas purification catalyst characterized by containing one or more oxides selected from titanium and aluminum.
以下に実施例を示し本発明の特徴を一層明確にする。なお本発明はこれら実施例の態様に限定されるものではない。
なお、実施例及び比較例中における各物性は、以下の方法により測定した。
（１）比表面積
比表面積計「フローソーブ−ＩＩ」（マイクロメリティクス製）を用い、ＢＥＴ法により測定した。
（２）細孔容積及び細孔半径
測定装置「Ａｕｔｏｓｏｒｂ−１，Ｑｕａｎｔａｃｈｒｏｍｅ（ＭＯＤＥＬ ＮＯ．ＡＳ１ＫＲ）」を用い、ＢＪＨ法により測定した。The following examples illustrate the features of the present invention more clearly. In addition, this invention is not limited to the aspect of these Examples.
In addition, each physical property in an Example and a comparative example was measured with the following method.
(1) Specific surface area A specific surface area meter “Flowsorb-II” (manufactured by Micromeritics) was used for measurement by the BET method.
(2) Measured by BJH method using a pore volume and pore radius measuring device “Autosorb-1, Quantachrome (MODEL NO. AS1KR)”.
〔実施例１〕
塩基性硫酸ジルコニウム（ＺｒＯ２として、濃度６．５％）１１０８ｇに、硝酸セリウム（ＣｅＯ２として、濃度２８．０％）溶液７６ｇ、硝酸ランタン溶液（Ｌａ２Ｏ３として、濃度２０％）８．５ｇ、硝酸ネオジウム溶液（Ｎｄ２Ｏ３として、濃度２５％）の溶液２０ｇおよびジニトロジアンミン白金硝酸溶液（Ｐｔとして、濃度４．５％）２２２ｍｇを添加した後、複合溶液２０００ｇになるように純水を加え、均一な溶液になるまで攪拌を行った。
そして、この複合溶液に２５％水酸化ナトリウム水溶液５００ｇを添加し、ｐＨを１３．３にした。次いで、生成した複合水酸化物をろ過し、純水を用いて水洗を行った。
得られた複合水酸化物を純水を加え分散し、２０００ｇにした。この後、ｐＨ８．０になるまで濃硝酸を添加し、次いでｐＨ１０．０になるまで２５％のアンモニア水を添加した。この生成した複合水酸化物をろ過した後、純水を用いて水洗を行った。得られた複合水酸化物を電気炉にて７００℃で７時間焼成した。
以上により、貴金属含有複合金属酸化物１００ｇを得た。
この貴金属含有複合金属酸化物（Ｆｒｅｓｈと称する）の比表面積及び気孔容量を求めた。次に、この貴金属含有複合金属酸化物を１０５０℃で２４時間焼成し、焼成後の比表面積及び気孔容量を求めた。結果を表１、図１及び図２に示す。[Example 1]
7. 1108 g of basic zirconium sulfate (ZrO 2 , concentration 6.5%), cerium nitrate (CeO 2 , concentration 28.0%) solution 76 g, lanthanum nitrate solution (La 2 O 3 , concentration 20%) After adding 5 g, 20 g of a neodymium nitrate solution (concentration 25% as Nd 2 O 3 ) and 222 mg of dinitrodiammine platinum nitric acid solution (concentration 4.5% as Pt), pure water so as to be a composite solution 2000 g And stirred until a homogeneous solution was obtained.
Then, 500 g of 25% aqueous sodium hydroxide solution was added to this composite solution to adjust the pH to 13.3. Next, the produced composite hydroxide was filtered and washed with pure water.
The obtained composite hydroxide was dispersed by adding pure water to 2000 g. After this, concentrated nitric acid was added until pH 8.0 and then 25% aqueous ammonia was added until pH 10.0. The produced composite hydroxide was filtered, and then washed with pure water. The obtained composite hydroxide was baked in an electric furnace at 700 ° C. for 7 hours.
Thus, 100 g of a noble metal-containing composite metal oxide was obtained.
The specific surface area and pore volume of this noble metal-containing composite metal oxide (referred to as Fresh) were determined. Next, this noble metal-containing composite metal oxide was fired at 1050 ° C. for 24 hours, and the specific surface area and pore volume after firing were determined. The results are shown in Table 1, FIG. 1 and FIG.
〔実施例２〕
ジニトロジアンミン白金硝酸溶液（Ｐｔとして、濃度４．５％）２２２ｍｇの替わりに硝酸ロジウム溶液（Ｒｈとして、濃度４．５％）２２２ｍｇとした以外は、実施例１と同様にして、貴金属含有複合金属酸化物を得た。結果を表１、図１及び図２に示す。[Example 2]
Precious metal-containing composite metal in the same manner as in Example 1, except that 222 mg of rhodium nitrate solution (concentration: 4.5%) was replaced with 222 mg of dinitrodiammine platinum nitrate solution (concentration: 4.5%) as Pt. An oxide was obtained. The results are shown in Table 1, FIG. 1 and FIG.
〔比較例１〕
白金を添加しなかった以外は、実施例１同様にして、貴金属含有複合金属酸化物を得た。
結果を表１、図１及び図２に示す。[Comparative Example 1]
A noble metal-containing composite metal oxide was obtained in the same manner as in Example 1 except that platinum was not added.
The results are shown in Table 1, FIG. 1 and FIG.
〔比較例２〕
比較例１と同様にして作製したジルコニア−セリア複合酸化物１００ｇに、ジニトロジアンミン白金硝酸溶液（Ｐｔとして、濃度４．５ｗｔ％）２２２ｍｇ含浸し、１５０℃で１２時間乾燥した後、５００℃で５時間焼成した。
この貴金属含有複合金属酸化物（Ｆｒｅｓｈと称する）の比表面積及び気孔容量を求めた。次に、この貴金属含有複合金属酸化物を１０５０℃で２４時間焼成し、焼成後の比表面積及び気孔容量を求めた。結果を表１、図１及び図２に示す。[Comparative Example 2]
100 g of the zirconia-ceria composite oxide produced in the same manner as in Comparative Example 1 was impregnated with 222 mg of a dinitrodiammine platinum nitrate solution (concentration: 4.5 wt% as Pt), dried at 150 ° C. for 12 hours, and then heated at 500 ° C. for 5 hours. Baked for hours.
The specific surface area and pore volume of this noble metal-containing composite metal oxide (referred to as Fresh) were determined. Next, this noble metal-containing composite metal oxide was fired at 1050 ° C. for 24 hours, and the specific surface area and pore volume after firing were determined. The results are shown in Table 1, FIG. 1 and FIG.
〔比較例３〕
ジニトロジアンミン白金硝酸溶液（Ｐｔとして、濃度４．５％）２２２ｍｇの替わりに硝酸ロジウム溶液（Ｒｈとして、濃度４．５％）２２２ｍｇとした以外は、比較例２と同様にして、貴金属含有複合金属酸化物を得た。結果を表１、図１及び図２に示す。[Comparative Example 3]
Precious metal-containing composite metal in the same manner as Comparative Example 2 except that 222 mg of rhodium nitrate solution (concentration: 4.5%) was replaced with 222 mg of dinitrodiammine platinum nitrate solution (concentration: 4.5%) as Pt. An oxide was obtained. The results are shown in Table 1, FIG. 1 and FIG.
表１、図１及び図２から明らかなように、本発明品は、１０５０℃で２４時間焼成後の全気孔容量が０．２５ｃｃ／ｇ以上あることから、気孔容量の耐熱性に優れたものであることが判る。
具体的に説明すると、本発明の実施例１及び実施例２は、▲１▼金属を添加しなかった比較例１及び▲２▼貴金属を含浸法で坦持した比較例２及び比較例３（以下、▲１▼及び▲２▼をまとめて、後者という）のＦｒｅｓｈの比表面積が約５８〜６２ｍ２／ｇであるのに対して、約６８〜６９ｍ２／ｇと優れており、又、後者のＦｒｅｓｈの気孔容量が約０．４０〜０．４８ｃｃ／ｇであるのに対して、約０．６５〜０．６８ｃｃ／ｇと約１．３５〜１．７倍となっており、更に、１０５０℃で２４時間焼成後の気孔容量は、後者が０．１９〜０．２２ｃｃ／ｇであるのに対して、０．２９〜０．３０ｃｃ／ｇと約１．３〜１．６倍となっており、これらは全て本発明の貴金属添加による効果であり、非常に優れたものであることが判る。As is clear from Table 1, FIG. 1 and FIG. 2, the product of the present invention has excellent pore volume heat resistance because the total pore volume after firing at 1050 ° C. for 24 hours is 0.25 cc / g or more. It turns out that it is.
Specifically, Example 1 and Example 2 of the present invention are: (1) Comparative Example 1 and (2) Comparative Example 2 and Comparative Example 3 in which noble metal was supported by impregnation method Hereinafter, (1) and (2) are collectively referred to as the latter) and the specific surface area of Fresh is about 58 to 62 m 2 / g, while it is excellent at about 68 to 69 m 2 / g. The latter Fresh has a pore volume of about 0.40 to 0.48 cc / g, and is about 0.65 to 0.68 cc / g, about 1.35 to 1.7 times. The pore volume after calcination at 1050 ° C. for 24 hours is 0.29 to 0.30 cc / g, about 1.3 to 1.6 times, while the latter is 0.19 to 0.22 cc / g. These are all the effects of the addition of the noble metal of the present invention and are found to be very excellent.
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| MY158376A (en) | 2013-06-04 | 2016-09-26 | Nippon Denko | Ceria-zirconia-based composite oxide and method of production of the same |
| JP7403458B2 (en) * | 2018-01-08 | 2023-12-22 | 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 | Method for manufacturing oxygen storage material |
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