JP3689938B2 - Method for producing cerium-zirconium composite - Google Patents
Method for producing cerium-zirconium composite Download PDFInfo
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- JP3689938B2 JP3689938B2 JP18915195A JP18915195A JP3689938B2 JP 3689938 B2 JP3689938 B2 JP 3689938B2 JP 18915195 A JP18915195 A JP 18915195A JP 18915195 A JP18915195 A JP 18915195A JP 3689938 B2 JP3689938 B2 JP 3689938B2
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- 239000002131 composite material Substances 0.000 title claims description 19
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- RCFVMJKOEJFGTM-UHFFFAOYSA-N cerium zirconium Chemical compound [Zr].[Ce] RCFVMJKOEJFGTM-UHFFFAOYSA-N 0.000 title claims description 8
- 229920000609 methyl cellulose Polymers 0.000 claims description 36
- 239000001923 methylcellulose Substances 0.000 claims description 36
- 235000010981 methylcellulose Nutrition 0.000 claims description 36
- 238000002441 X-ray diffraction Methods 0.000 claims description 35
- 239000000843 powder Substances 0.000 claims description 33
- 229910052726 zirconium Inorganic materials 0.000 claims description 30
- 229910052684 Cerium Inorganic materials 0.000 claims description 29
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 24
- 239000000243 solution Substances 0.000 claims description 19
- 229920002472 Starch Polymers 0.000 claims description 12
- 239000008107 starch Substances 0.000 claims description 12
- 235000019698 starch Nutrition 0.000 claims description 12
- 229920000663 Hydroxyethyl cellulose Polymers 0.000 claims description 10
- 239000004354 Hydroxyethyl cellulose Substances 0.000 claims description 10
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 claims description 10
- 235000002732 Allium cepa var. cepa Nutrition 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 8
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- 229920002153 Hydroxypropyl cellulose Polymers 0.000 claims description 7
- 239000001863 hydroxypropyl cellulose Substances 0.000 claims description 7
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- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 claims description 7
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 claims description 7
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 claims description 7
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 claims description 7
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- 238000010438 heat treatment Methods 0.000 claims description 5
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- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 claims description 3
- 239000006104 solid solution Substances 0.000 claims description 3
- 244000291564 Allium cepa Species 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 33
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 26
- 230000000052 comparative effect Effects 0.000 description 17
- 238000010304 firing Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 10
- OERNJTNJEZOPIA-UHFFFAOYSA-N zirconium nitrate Chemical compound [Zr+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O OERNJTNJEZOPIA-UHFFFAOYSA-N 0.000 description 10
- 229910000420 cerium oxide Inorganic materials 0.000 description 9
- 239000000084 colloidal system Substances 0.000 description 9
- 239000002245 particle Substances 0.000 description 9
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 8
- 241000234282 Allium Species 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 239000003054 catalyst Substances 0.000 description 6
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 6
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 4
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 4
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- 238000005470 impregnation Methods 0.000 description 3
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- DUFCMRCMPHIFTR-UHFFFAOYSA-N 5-(dimethylsulfamoyl)-2-methylfuran-3-carboxylic acid Chemical compound CN(C)S(=O)(=O)C1=CC(C(O)=O)=C(C)O1 DUFCMRCMPHIFTR-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- 108010010803 Gelatin Proteins 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- VGBWDOLBWVJTRZ-UHFFFAOYSA-K cerium(3+);triacetate Chemical compound [Ce+3].CC([O-])=O.CC([O-])=O.CC([O-])=O VGBWDOLBWVJTRZ-UHFFFAOYSA-K 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
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- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000002243 precursor Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
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- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 150000000703 Cerium Chemical class 0.000 description 1
- 229910004625 Ce—Zr Inorganic materials 0.000 description 1
- 102000008186 Collagen Human genes 0.000 description 1
- 108010035532 Collagen Proteins 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052776 Thorium Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
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- 238000003915 air pollution Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000003637 basic solution Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- DRVWBEJJZZTIGJ-UHFFFAOYSA-N cerium(3+);oxygen(2-) Chemical class [O-2].[O-2].[O-2].[Ce+3].[Ce+3] DRVWBEJJZZTIGJ-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 229910052739 hydrogen Inorganic materials 0.000 description 1
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- 239000002184 metal Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
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- 238000002360 preparation method Methods 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
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- 230000000717 retained effect Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- RPACBEVZENYWOL-XFULWGLBSA-M sodium;(2r)-2-[6-(4-chlorophenoxy)hexyl]oxirane-2-carboxylate Chemical compound [Na+].C=1C=C(Cl)C=CC=1OCCCCCC[C@]1(C(=O)[O-])CO1 RPACBEVZENYWOL-XFULWGLBSA-M 0.000 description 1
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- 150000003754 zirconium Chemical class 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
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- Inorganic Compounds Of Heavy Metals (AREA)
- Catalysts (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は自動車等の内燃機関より排出される排気ガスの浄化用ハニカム触媒に用いることができるセリウム−ジルコニウム複合体の製造方法に関し、特に大気汚染の防止を目的として自動車排気ガス中の有害成分である炭化水素（ＨＣ）、一酸化炭素（ＣＯ）、一酸化窒素（ＮＯ）を同時に浄化する排気ガス浄化用触媒に用いることができるセリウム−ジルコニウム複合体の製造方法に関する。
【０００２】
【従来の技術】
従来、内燃機関から排出される排気ガス中の有害成分を浄化する排気ガス浄化用触媒は種々提案されており、現在一般的な自動車の排気ガス浄化用ハニカム触媒は、ハニカム担体の軸方向に整列した管状通路に、白金、ロジウム、パラジウム等の触媒活性物質と、触媒活性物質を分布するための大きな表面積を得るようにする耐熱性物質、および酸素の吸収、放出により排気ガス中の酸素濃度の変動を緩和する酸素ストレージ能を持つ酸化物がともに塗布されている。
【０００３】
このような酸素ストレージ能を持つ物質としては酸化セリウムが一般的であるが、これは高温雰囲気のような厳しい条件下で使用されると粒子成長が起こりやすく、比表面積が大幅に低下し、触媒の浄化性能を悪化させる。そこで酸化セリウムの粒子成長を抑制するために、希土類元素により安定化された酸化セリウムが種々提案されている。特開昭６３−１１６７４１号公報では、ジルコニウムと複合したセリウム酸化物、あるいは特開昭６２−５６３２２号公報にはアルミニウム、ケイ素、ジルコニウム、トリウムおよび希土類金属元素より選ばれた金属元素の酸化物を含有する酸化セリウムが開示されている。
【０００４】
一方、酸化物の焼成助剤として有機物粉末の利用は、特開平０５−２９００７号、特開平０２−４９３５７号、特開平０５−２９００８号、特開平０４−１３９０５４号各公報等に種々提案されているが、これらは焼成時の収縮や多孔度、更には加圧時の形状保持性を得ようとするものであり、異種の元素から複合体を得るものではない。
【０００５】
【発明が解決しようとする課題】
しかしながら、前記特開昭６３−１１６７４１号公報に開示されているような触媒層にセリウムとジルコニウムの混合溶液を含浸担持する製造法では、セリウムとジルコニウムの複合は完全であり、用いた量を完全に活用できない。また前記特開昭６２−５６３２２号公報では製造法として含浸担持に加え、酸性混合溶液に塩基性溶液を加える共沈法が開示されているが、このような水酸化物による沈殿を利用する方法では、水酸化物を生じるｐＨが異なるため、均一性の低下や複合化の低下が見られ、良い反復性のある結果が得られにくく、また沈殿材の除去などの工程数が多くなり経済的に不利であるという問題がある。
【０００６】
従って、本発明の目的は、高温雰囲気下で粒成長が抑えられ、高温雰囲気に曝されても高い酸素ストレージ能を有するジルコニウムとセリウムの複合体を、より少ない工程数で、かつより反復性が高く得られる経済的に有利な製造法を提供することである。
【０００７】
【課題を解決するための手段】
本発明者等は、鋭意研究の結果、セリウム塩水溶液とジルコニウム塩水溶液の混合溶液に有機物粉末あるいは有機物粉末によるコロイド溶液を加え混合操作した後に、固体化せしめる製造法により、少ない工程数で、かつより反復性が高く、単独の酸化セリウム、酸化ジルコニウムが見られない、良好な複合体が得られることを見いだした。
【０００８】
即ち、本発明は単独のＺｒＯ2 がＸ線回折により見られない、セリウム（Ｃｅ）とジルコニウム（Ｚｒ）の複合酸化物または固溶体である複合体を製造するに当たり、ＣｅおよびＺｒを含む混合水溶液に、焼成により完全に熱分解する有機物粉末あるいは有機物粉末によるコロイド溶液を添加混合した後に、加熱処理により固体化することを特徴とする。
【０００９】
【発明の実施の形態】
本発明のセリウム−ジルコニウム複合体の製造方法は、単独のＺｒＯ2 がＸ線回折により見られない、セリウム（Ｃｅ）とジルコニウム（Ｚｒ）の複合酸化物または固溶体である複合体を製造するに当たり、ＣｅおよびＺｒを含む混合水溶液に、焼成により完全に熱分解する有機物粉末あるいは有機物粉末によるコロイド溶液を添加混合した後に、加熱処理により固体化するものである。
【００１０】
本発明によれば、セリウムとジルコニウムの均一な混合溶液に、繊維状の有機物を加え有機線形コロイドとしたことで、溶液中のセリウムとジルコニウムが繊維物質を構成する結晶配列構造の枠内に取り込まれるか、あるいは線形コロイドによる高粘度により再移動が抑制されるため、乾燥工程後にセリウムとジルコニウムの分離、偏析が抑制された前駆体が得られ、比較的低温の焼成により十分な複合化が得られる。従って本発明によれば、該複合体が少ない工程数で得られ、またセリウムとジルコニウムは機械的に分散させ得ることが可能なため、反復性ある結果が得られやすい。
【００１１】
本発明に有機物粉末を用いたのは、焼成により完全に熱分解させ、意図した組成以外の元素が残留するのを妨げるためである。さらに有機物である繊維状粒子は溶媒中で長い粒子が互いに絡み合った線形コロイドとなるために、一般的に高粘度となることが知られている。また、繊維状粒子は構成する分子内に、結晶部分を連結している結晶配列構造があり、その構造の枠内に分散粒子を取り込み、粒子を安定する事も知られている。従って、前述したように、均一にしたセリウムとジルコニウムを線形コロイド内に取り込むか、あるいは繊維状粒子内の枠組み構造内に取り込むことで、セリウムとジルコニウムの合一による凝集あるいは再移動を妨げることができる。
【００１２】
本発明で使用される有機物粉末としては、例えばメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシプロヒルセルロースおよびヒドロキシプロピルメチルセルロースからなる群から選ばれた少なくとも１種のセルロース誘導体あるいは馬鈴薯澱粉、玉蜀黍澱粉等のいずれかあるいは混合物である澱粉質である。メチルセルロースは冷水に可溶であり、無機塩の添加により粘度が増すため本発明に適する。また澱粉質は加温により粘度上昇するため、乾燥工程での分離抑制が期待でき本発明に適当である。カルボキシメチルセルロースは化合物名からは、Ｃ，Ｈ，Ｏ以外の元素を含まないようであるが、実際には水可溶性のＮａ塩であるため、ｐＨにより粘度が変化し好ましくない。一方グリコーゲンの様な球形コロイドを作る有機物粉末は、その構造から高粘度が得られないので好ましくない。またコラーゲン等の線形コロイドを作るタンパク質は、触媒毒となる硫黄を含むため好ましくない。更にゼラチン質は昇温途中すなわち乾燥工程で粘度低下を生じ、保持されていたセリウム、ジルコニウムの再移動が生じやすく好ましくない。
【００１３】
本発明で使用されるセリウム源としては硝酸セリウム、酢酸セリウム等が用いられ、ジルコニウム源としては硝酸ジルコニウム、酢酸ジルコニウム等が用いられる。溶液中のセリウム、ジルコニウムの均一性、安定性を保つには、塩の種類を揃えることが好ましい。
【００１４】
これらのセリウムとジルコニウムが溶液中に均一に分散されるために、十分な混合を行う必要があるが、これには攪拌機、乳化分散機、スタティックミキサなどいずれを用いてもかまわない。
有機物粉末は、粉末のまま添加しても、水に溶かしてコロイド溶液として添加しても構わない。
【００１５】
添加後の混合は、前混合と同様な装置を用い、より長く行われる。コロイド状態とした混合溶液の乾燥は、焼成時にセリウム、ジルコニウムの再移動が起きないようにオーブン内で十分行われるが、速やかに行うためにスプレードライヤー等を用いて微粒化して乾燥しても構わない。
乾燥した固形物は２５０℃以上の焼成により固定化されるが、より大きな比表面積を得るためには５００℃以下の焼成とすることが好ましい。かかる範囲で焼成することにより上記目的に合致した複合体が得られる。
【００１６】
以上詳述したように、本発明方法は、優れた耐熱性を有し高温雰囲気下でも比表面積の低下が抑制される酸素ストレージ能酸化物に関して、少ない工程数かつ反復性のある経済的に有利な製造方法を提供できる。
【００１７】
【実施例】
本発明を次の実施例、比較例および試験例により説明する。
実施例１
セリウム６１１ｇを含む硝酸セリウム水溶液、およびジルコニウム１８５ｇを含む硝酸ジルコニウム水溶液を容器に量り取り、高速乳化分散機（特殊機化工業（株）製ホモミクサＨＶ−Ｍ型）を用いて７０００ｒｐｍ，１０分間予備攪拌混合した。攪拌混合を継続させつつ、これにメチルセルロース３７ｇを少量ずつ加え、更に１時間攪拌混合した。これを２５０℃に加熱したオーブン内で４時間乾燥し、次いで３００℃で１２時間焼成し、試料１を得た。試料１中からロットを１０個抽出し、試料１−１〜１−１０を得た。
【００１８】
実施例２
セリウム溶液を酢酸セリウム水溶液、ジルコニウム溶液を酢酸ジルコニウム水溶液とした以外は実施例１と同様にして試料２を得た。
【００１９】
実施例３
メチルセルロース添加量を５０ｇとした以外は、実施例１と同様にして試料３を得た。
【００２０】
実施例４
メチルセルロースをヒドロキシエチルセルロースとした以外は、実施例１と同様にして試料４を得た。
【００２１】
実施例５
メチルセルロースをヒドロキシエチルセルロースとした以外は、実施例１と同様にして試料５を得た。
【００２２】
実施例６
メチルセルロースをヒドロキシエチルセルロースとした以外は、実施例１と同様にして試料６を得た。
【００２３】
実施例７
メチルセルロース３７ｇを馬鈴薯澱粉５０ｇとした以外は、実施例１と同様にして試料７を得た。
【００２４】
実施例８
メチルセルロース３７ｇを玉蜀黍澱粉５０ｇとした以外は、実施例１と同様にして試料８を得た。
【００２５】
実施例９
メチルセルロース３７ｇをメチルセルロースおよびヒドロキシエチルセルロースがそれぞれ１８．５ｇずつ混合した有機物粉末とした以外は、実施例１と同様にして試料９を得た。
【００２６】
実施例１０
メチルセルロース３７ｇをメチルセルロースおよびヒドロキシプロピルセルロースがそれぞれ１８．５ｇずつ混合した有機物粉末とした以外は、実施例１と同様にして試料１０を得た。
【００２７】
実施例１１
メチルセルロース３７ｇをメチルセルロースおよびヒドロキシプロピルメチルセルロースがそれぞれ１８．５ｇずつ混合した有機物粉末とした以外は、実施例１と同様にして試料１１を得た。
【００２８】
実施例１２
メチルセルロース３７ｇを馬鈴薯澱粉２５ｇとメチルセルロース１８．５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料１２を得た。
【００２９】
実施例１３
メチルセルロース３７ｇを玉蜀黍澱粉２５ｇとメチルセルロース１８．５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料１３を得た。
【００３０】
実施例１４
メチルセルロース３７ｇをヒドロキシエチルセルロースおよびヒドロキシプロピルセルロースがそれぞれ１８．５ｇずつ混合した有機物粉末とした以外は、実施例１と同様にして試料１４を得た。
【００３１】
実施例１５
メチルセルロース３７ｇをヒドロキシエチルセルロースおよびヒドロキシプロピルメチルセルロースがそれぞれ１８．５ｇずつ混合した有機物粉末とした以外は、実施例１と同様にして試料１５を得た。
【００３２】
実施例１６
メチルセルロース３７ｇを馬鈴薯澱粉２５ｇとヒドロキシエチルセルロース１８．５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料１６を得た。
【００３３】
実施例１７
メチルセルロース３７ｇを玉蜀黍澱粉２５ｇとヒドロキシエチルセルロース１８．５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料１７を得た。
【００３４】
実施例１８
メチルセルロース３７ｇをヒドロキシプロピルセルロースおよびヒドロキシプロピルメチルセルロースがそれぞれ１８．５ｇずつ混合した有機物粉末とした以外は、実施例１と同様にして試料１８を得た。
【００３５】
実施例１９
メチルセルロース３７ｇをヒドロキシプロピルセルロース１８．５ｇと馬鈴薯澱粉２５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料１９を得た。
【００３６】
実施例２０
メチルセルロース３７ｇをヒドロキシプロピルセルロース１８．５ｇと玉蜀黍澱粉２５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料２０を得た。
【００３７】
実施例２１
メチルセルロース３７ｇをヒドロキシプロピルメチルセルロース１８．５ｇと馬鈴薯澱粉２５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料２１を得た。
【００３８】
実施例２２
メチルセルロース３７ｇをヒドロキシプロピルメチルセルロース１８．５ｇと玉蜀黍澱粉２５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料２２を得た。
【００３９】
実施例２３
メチルセルロース３７ｇを馬鈴薯澱粉２５ｇと玉蜀黍澱粉２５ｇが混合した有機物粉末とした以外は、実施例１と同様にして試料２３を得た。
【００４０】
実施例２４
メチルセルロース３７ｇをメチルセルロース（和光純薬製）３７ｇを水１８１３ｇに溶解したメチルセルロース水溶液１８５０ｇとした以外は、実施例１と同様にして試料２４を得た。
【００４１】
実施例２５
入口５００℃、出口２５０℃に設定したスプレードライヤー（大河原化工機製ＯＮ−１６Ｇ）を用いて乾燥した以外は、実施例１と同様にして試料２５を得た。
【００４２】
実施例２６
酸化セリウムを４０７ｇ、およびジルコニウムを３７０ｇとした以外は、実施例１と同様にして試料２６を得た。
【００４３】
比較例１
酸化セリウム７５０ｇにジルコニウム１８５ｇを含む硝酸ジルコニウム水溶液を含浸し、１５０℃で４時間乾燥した後、６００℃で２時間の焼成を行い、試料ａを得た（含浸法）。
【００４４】
比較例２
セリウム６１１ｇを含む硝酸セリウム水溶液、およびジルコニウム１８５ｇを含む硝酸ジルコニウム水溶液を容器に量り取り、これを攪拌しながら１Ｎアンモニウム水溶液をｐＨが９になるまで徐々に滴下した。
焼成した反応塊を当該溶液中で１時間攪拌した後に、濾過により固液分離を行った。次いで回収した濾過物を蒸留水１Ｌで２０分間洗浄し、再び濾過した。
この操作を６回繰り返した後に、１２０℃で１２時間乾燥し、次いで３００℃で１２時間焼成して試料ｂを得た（共沈法）。試料ｂ中からロットを１０個抽出し、試料ｂ−１〜ｂ−１０を得た。
【００４５】
比較例３
メチルセルロース３７ｇをグリコーゲン６０ｇとした以外は、実施例１と同様にして試料ｃを得た。
【００４６】
比較例４
メチルセルロース３７ｇを予め少量の純水を加えた市販のゼラチン粉末６０ｇとした以外は、実施例１と同様にして試料ｄを得た。
【００４７】
比較例５
メチルセルロース３７ｇをカルボキシメチルセルロース６０ｇとした以外は、実施例１と同様にして試料ｅを得た。
【００４８】
比較例６
酸化セリウムを５００ｇとし、更にジルコニウム３７０ｇを含む硝酸ジルコニウム溶液とした以外は比較例１と同様にして、試料ｆを得た。
上記実施例および比較例の原材料および添加物の組成並びに製造条件を表１に示す。
【００４９】
【表１】
試験例
上記実施例および比較例により得られた各試料は、１０ｇを磁性坩堝に入れ、空気雰囲気の電気炉に投入し、１０００℃で４時間保持する耐久試験を行った。
これらの試料を、広角Ｘ線解説法により、理学電機製ＲＡＤ−Ｂ型を用いて、（１１１）面でＣｅＯ2 （立方晶）、ＺｒＯ2 （正方晶）のピークが現れる角度範囲を精密測定した。
測定結果より、ＺｒＯ2 （正方晶）単独ピーク（３０．１９°）の有無、および最大ピークのピークトップ測定角度および半値幅より結晶子径と格子定数を算出し比較を行った。
【００５１】
即ち、ピークトップ高さの１／２高さのピーク幅を半値幅とし、トップ位置を２θとして以下のように結晶子径、格子定数を算出し、比較を行った。
▲１▼結晶子径の算出法
結晶子径（Ａ）＝０．９×λ／（半値幅×ｃｏｓ（２θ／２））
λは装置固有の値、本例では１．５４１９
▲２▼格子定数
ｄ値を算出する。
ｄ＝λ／（２×ｓｉｎθ）
このｄ値に対して、本例の測定は結晶面が（１１１）面なので、
【数１】
√（１2 ＋１2 ＋１2 ）を乗じ、格子定数を算出する。
格子定数＝λ／（２×ｓｉｎθ）×√３
実施例および比較例で得た試料１〜２６及び試料ａ〜ｆについて、測定ピークを図１〜３２に示し、単独ピークの有無、結晶子径、格子定数を表２に示す。
【００５２】
【表２】
図１において、主ピークは、ＣｅＯ2 単独ピークとＣｅＯ2 単独ピークの間に有り、Ｃｅ−Ｚｒの複合体によるものである。ＣｅＯ2 ，ＺｒＯ2 それぞれの単独ピークは見られない。図２〜２６において、試料１と同様な複合体ピークが認められ、単独ピークは見られない。図２７において、分離したＺｒＯ2 単独ピークが見られ、図２８において、試料１と同様に複合体ピークが見られず、図２９において小さい分離したＺｒＯ2 単独ピークが見られ、図３０，３１および３２において、分離したＺｒＯ2 単独ピークが見られる。
【００５４】
セルロース誘導体あるいは澱粉質を加えて調整した試料のＸ線測定図からは、ＺｒＯ2 （正方晶）ピークが見られないが、含浸法による試料やグリコーゲンあるいはゼラチンによる試料からはＺｒＯ2 （正方晶）ピークが見られた表２の格子定数からも、実施例による試料はＺｒの全てがＣｅと複合化していることが解るが、共沈法以外の比較例による試料ではＣｅとＺｒの複合化が十分でないことを示している。即ち、一般的に報告されている格子定数について調べると、ＣｅＯ2 の格子定数５．４１１、ＺｒＯ2 の格子定数５．２１３であり、本発明のようなＺｒと複合化したＣｅＯ2 はこの間にピークトップを持つ。Ｚｒと複合化したＣｅＯ2 について、やはり一般的に報告されている格子定数を調べると、実施例と同様の組成であるＣｅ0.75Ｚｒ0.25Ｏ2 は５．３４９であった。表２に示された実施例の格子定数は、ＣｅＯ2 の５．４１１よりこの５．３４９に近く、比較例はほとんどＣｅＯ2 の５．４１１と同様であることから、実施例はＺｒとＣｅが複合化しているが、共沈法を除く比較例はＣｅとＺｒの複合化が不十分であると判断した。
【００５５】
また実施例１の試料１−１〜１−１０及び比較例２の試料ｂ−１〜ｂ−１０について、単独ピークの有無、結晶子径、格子定数を表３に示す。
表３より格子定数は実施例１が共沈法である比較例２より変動が少なく、本発明により、より優れた反復性が得られることが解った。
表２の実施例は種々の試作法により調製されたもので同一物とは言えないので、これらを比較して変動量を評価はできない。
試料１の調製法を用いてロット間の変動を評価したものが表３であり、その３δは共沈法である比較例２より小さいため、変動が少ないと判断した。
【００５６】
【表３】
【発明の効果】
本発明によれば、セリウムとジルコニウムの均一な混合溶液に、有機物粉末あるいは有機物粉末によるコロイドを加え有機線形コロイドとしたことで、溶液中のセリウムとジルコニウムが繊維物質を構成する結晶配列構造の枠内に取り込まれるか、あるいは線形コロイドによる高粘度により再移動が抑制されるため、乾燥工程後にセリウムとジルコニウムの分離、偏析が抑制された前駆体が得られ、比較的低温の焼成により十分な複合化が得られる。従って本発明によれば、少ない工程数でまたセリウムとジルコニウムは機械的に分散させ得ることが可能なため、反復性ある結果として該複合体を提供できる。
【図面の簡単な説明】
【図１】試料１のＸ線回折ピークを示す線図である。
【図２】試料２のＸ線回折ピークを示す線図である。
【図３】試料３のＸ線回折ピークを示す線図である。
【図４】試料４のＸ線回折ピークを示す線図である。
【図５】試料５のＸ線回折ピークを示す線図である。
【図６】試料６のＸ線回折ピークを示す線図である。
【図７】試料７のＸ線回折ピークを示す線図である。
【図８】試料８のＸ線回折ピークを示す線図である。
【図９】試料９のＸ線回折ピークを示す線図である。
【図１０】試料１０のＸ線回折ピークを示す線図である。
【図１１】試料１１のＸ線回折ピークを示す線図である。
【図１２】試料１２のＸ線回折ピークを示す線図である。
【図１３】試料１３のＸ線回折ピークを示す線図である。
【図１４】試料１４のＸ線回折ピークを示す線図である。
【図１５】試料１５のＸ線回折ピークを示す線図である。
【図１６】試料１６のＸ線回折ピークを示す線図である。
【図１７】試料１７のＸ線回折ピークを示す線図である。
【図１８】試料１８のＸ線回折ピークを示す線図である。
【図１９】試料１９のＸ線回折ピークを示す線図である。
【図２０】試料２０のＸ線回折ピークを示す線図である。
【図２１】試料２１のＸ線回折ピークを示す線図である。
【図２２】試料２２のＸ線回折ピークを示す線図である。
【図２３】試料２３のＸ線回折ピークを示す線図である。
【図２４】試料２４のＸ線回折ピークを示す線図である。
【図２５】試料２５のＸ線回折ピークを示す線図である。
【図２６】試料２６のＸ線回折ピークを示す線図である。
【図２７】試料ａのＸ線回折ピークを示す線図である。
【図２８】試料ｂのＸ線回折ピークを示す線図である。
【図２９】試料ｃのＸ線回折ピークを示す線図である。
【図３０】試料ｄのＸ線回折ピークを示す線図である。
【図３１】試料ｅのＸ線回折ピークを示す線図である。
【図３２】試料ｆのＸ線回折ピークを示す線図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a cerium-zirconium composite that can be used in a honeycomb catalyst for purifying exhaust gas discharged from an internal combustion engine such as an automobile, and more particularly to harmful components in automobile exhaust gas for the purpose of preventing air pollution. The present invention relates to a method for producing a cerium-zirconium composite that can be used as an exhaust gas purifying catalyst that simultaneously purifies certain hydrocarbons (HC), carbon monoxide (CO), and nitric oxide (NO).
[0002]
[Prior art]
Conventionally, various exhaust gas purifying catalysts for purifying harmful components in exhaust gas discharged from an internal combustion engine have been proposed. Currently, general exhaust gas purifying honeycomb catalysts for automobiles are aligned in the axial direction of the honeycomb carrier. In the tubular passage, a catalytically active substance such as platinum, rhodium and palladium, a heat-resistant substance which obtains a large surface area for distributing the catalytically active substance, and oxygen concentration in the exhaust gas by absorbing and releasing oxygen Both oxides with oxygen storage ability to mitigate fluctuations are applied.
[0003]
Cerium oxide is generally used as such a substance having an oxygen storage capacity, but when used under severe conditions such as a high temperature atmosphere, particle growth is likely to occur, and the specific surface area is greatly reduced. Worsens the purification performance. Accordingly, various cerium oxides stabilized by rare earth elements have been proposed in order to suppress cerium oxide particle growth. In JP-A-63-116741, cerium oxide complexed with zirconium, or in JP-A-62-56322, an oxide of a metal element selected from aluminum, silicon, zirconium, thorium and a rare earth metal element is used. The containing cerium oxide is disclosed.
[0004]
On the other hand, the use of organic powders as oxide firing aids has been proposed in various ways, such as in Japanese Patent Application Laid-Open Nos. 05-29007, 02-49357, 05-29008, and 04-139054. However, these are intended to obtain shrinkage and porosity during firing and shape retention during pressurization, and do not obtain a composite from different elements.
[0005]
[Problems to be solved by the invention]
However, in the manufacturing method in which a mixed solution of cerium and zirconium is impregnated and supported on the catalyst layer as disclosed in Japanese Patent Laid-Open No. 63-116741, the composite of cerium and zirconium is complete, and the amount used is completely It cannot be used for. Japanese Patent Laid-Open No. 62-56322 discloses a coprecipitation method in which a basic solution is added to an acidic mixed solution in addition to impregnation support as a production method, but a method using precipitation by such a hydroxide. Since the pH at which hydroxide is generated is different, there is a decrease in homogeneity and complexing, and it is difficult to obtain good repeatability, and the number of steps such as precipitation material removal is increased, which is economical. There is a problem that it is disadvantageous.
[0006]
Therefore, the object of the present invention is to reduce the number of steps and to increase the repeatability of a complex of zirconium and cerium that has a high oxygen storage capacity even when exposed to a high temperature atmosphere. It is to provide an economically advantageous production method that is highly obtainable.
[0007]
[Means for Solving the Problems]
As a result of diligent research, the present inventors have reduced the number of steps by a manufacturing method in which an organic powder or a colloidal solution of an organic powder is added to a mixed solution of a cerium salt aqueous solution and a zirconium salt aqueous solution and mixed, and then solidified. It has been found that a good composite can be obtained which is more repeatable and does not show single cerium oxide or zirconium oxide.
[0008]
That is, the present invention provides a mixed aqueous solution containing Ce and Zr in the production of a composite oxide or solid solution of cerium (Ce) and zirconium (Zr), in which no single ZrO 2 is found by X-ray diffraction. The method is characterized in that an organic powder that is completely pyrolyzed by firing or a colloidal solution of the organic powder is added and mixed, and then solidified by heat treatment.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The method for producing a cerium-zirconium composite of the present invention is to produce a composite that is a composite oxide or solid solution of cerium (Ce) and zirconium (Zr), in which no single ZrO 2 is observed by X-ray diffraction. An organic powder that is completely pyrolyzed by firing or a colloidal solution of an organic powder is added to and mixed with an aqueous solution containing Ce and Zr, and then solidified by heat treatment.
[0010]
According to the present invention, by adding a fibrous organic substance to a uniform mixed solution of cerium and zirconium to form an organic linear colloid, cerium and zirconium in the solution are incorporated into the frame of the crystal arrangement structure constituting the fiber substance. Or the high viscosity due to the linear colloid suppresses remigration, resulting in a precursor in which separation and segregation of cerium and zirconium are suppressed after the drying process, and sufficient complexation is obtained by firing at a relatively low temperature. It is done. Therefore, according to the present invention, the composite can be obtained with a small number of steps, and cerium and zirconium can be mechanically dispersed. Therefore, it is easy to obtain a repeatable result.
[0011]
The reason why the organic powder is used in the present invention is that it is completely pyrolyzed by firing and prevents elements other than the intended composition from remaining. Furthermore, it is known that fibrous particles that are organic substances generally have a high viscosity because long particles in a solvent become linear colloids intertwined with each other. Further, it is also known that the fibrous particles have a crystal arrangement structure in which crystal parts are connected in molecules constituting the particles, and dispersed particles are taken into the frame of the structure to stabilize the particles. Therefore, as described above, uniform cerium and zirconium are incorporated into the linear colloid or incorporated into the framework structure within the fibrous particles, thereby preventing aggregation or re-migration due to coalescence of cerium and zirconium. it can.
[0012]
The organic powder used in the present invention is, for example, at least one cellulose derivative selected from the group consisting of methylcellulose, hydroxyethylcellulose, hydroxypropyl cellulose and hydroxypropylmethylcellulose, potato starch, onion starch and the like, or a mixture thereof. It is starchy. Methylcellulose is soluble in cold water and is suitable for the present invention because its viscosity is increased by the addition of inorganic salts. Further, since starch increases in viscosity due to heating, it can be expected to suppress separation in the drying process and is suitable for the present invention. Carboxymethylcellulose does not appear to contain any elements other than C, H, and O from the name of the compound, but is actually a water-soluble Na salt, which is not preferable because the viscosity changes depending on pH. On the other hand, an organic powder that forms a spherical colloid such as glycogen is not preferable because high viscosity cannot be obtained from its structure. Also, proteins that form linear colloids such as collagen are not preferred because they contain sulfur which is a catalyst poison. Further, the gelatinous material is not preferable because the viscosity is lowered during the temperature rising, that is, in the drying process, and the retained cerium and zirconium are likely to move again.
[0013]
As the cerium source used in the present invention, cerium nitrate, cerium acetate or the like is used, and as the zirconium source, zirconium nitrate, zirconium acetate or the like is used. In order to maintain the uniformity and stability of cerium and zirconium in the solution, it is preferable to use the same type of salt.
[0014]
In order for these cerium and zirconium to be uniformly dispersed in the solution, it is necessary to perform sufficient mixing. For this purpose, any of a stirrer, an emulsifying disperser, a static mixer, and the like may be used.
The organic powder may be added as a powder or may be dissolved in water and added as a colloidal solution.
[0015]
The mixing after the addition is performed for a longer time using the same apparatus as the premixing. Drying of the mixed solution in colloidal state is sufficiently performed in an oven so that re-transfer of cerium and zirconium does not occur at the time of firing, but in order to perform it quickly, it may be atomized and dried using a spray dryer or the like. Absent.
The dried solid is fixed by firing at 250 ° C. or higher, but in order to obtain a larger specific surface area, firing at 500 ° C. or lower is preferable. By firing in such a range, a composite meeting the above-mentioned purpose can be obtained.
[0016]
As described above in detail, the method of the present invention is economically advantageous with a small number of steps and repeatability with respect to an oxide storage ability oxide that has excellent heat resistance and suppresses a decrease in specific surface area even under a high temperature atmosphere. A simple manufacturing method can be provided.
[0017]
【Example】
The invention is illustrated by the following examples, comparative examples and test examples.
Example 1
A cerium nitrate aqueous solution containing 611 g of cerium and a zirconium nitrate aqueous solution containing 185 g of zirconium are weighed in a container, and pre-stirred at 7000 rpm for 10 minutes using a high-speed emulsifying disperser (Homomixer HV-M type manufactured by Tokushu Kika Kogyo Co., Ltd.). Mixed. While continuing the stirring and mixing, 37 g of methylcellulose was added little by little, followed by further stirring and mixing for 1 hour. This was dried in an oven heated to 250 ° C. for 4 hours and then calcined at 300 ° C. for 12 hours to obtain Sample 1. Ten lots were extracted from Sample 1 to obtain Samples 1-1 to 1-10.
[0018]
Example 2
Sample 2 was obtained in the same manner as in Example 1 except that the cerium solution was an aqueous cerium acetate solution and the zirconium solution was an aqueous zirconium acetate solution.
[0019]
Example 3
Sample 3 was obtained in the same manner as in Example 1 except that the amount of methylcellulose added was 50 g.
[0020]
Example 4
Sample 4 was obtained in the same manner as in Example 1 except that methylcellulose was replaced with hydroxyethylcellulose.
[0021]
Example 5
Sample 5 was obtained in the same manner as in Example 1 except that methylcellulose was replaced with hydroxyethylcellulose.
[0022]
Example 6
Sample 6 was obtained in the same manner as in Example 1 except that methylcellulose was replaced with hydroxyethylcellulose.
[0023]
Example 7
Sample 7 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to 50 g of potato starch.
[0024]
Example 8
Sample 8 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to 50 g of onion starch.
[0025]
Example 9
Sample 9 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was used as an organic powder in which 18.5 g of methylcellulose and hydroxyethylcellulose were mixed.
[0026]
Example 10
Sample 10 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was used as an organic powder in which 18.5 g of methylcellulose and hydroxypropylcellulose were mixed.
[0027]
Example 11
Sample 11 was obtained in the same manner as in Example 1, except that 37 g of methylcellulose was used as an organic powder in which 18.5 g of methylcellulose and hydroxypropylmethylcellulose were mixed.
[0028]
Example 12
Sample 12 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to an organic powder in which 25 g of potato starch and 18.5 g of methylcellulose were mixed.
[0029]
Example 13
Sample 13 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to an organic powder in which 25 g of onion starch and 18.5 g of methylcellulose were mixed.
[0030]
Example 14
Sample 14 was obtained in the same manner as in Example 1, except that 37 g of methylcellulose was used as an organic powder in which 18.5 g of hydroxyethylcellulose and hydroxypropylcellulose were mixed.
[0031]
Example 15
Sample 15 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was used as an organic powder in which 18.5 g of hydroxyethylcellulose and hydroxypropylmethylcellulose were mixed.
[0032]
Example 16
Sample 16 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to an organic powder in which 25 g of potato starch and 18.5 g of hydroxyethylcellulose were mixed.
[0033]
Example 17
Sample 17 was obtained in the same manner as in Example 1, except that 37 g of methylcellulose was changed to an organic powder in which 25 g of onion starch and 18.5 g of hydroxyethylcellulose were mixed.
[0034]
Example 18
Sample 18 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was used as an organic powder in which 18.5 g of hydroxypropylcellulose and hydroxypropylmethylcellulose were mixed.
[0035]
Example 19
Sample 19 was obtained in the same manner as in Example 1, except that 37 g of methylcellulose was changed to an organic powder in which 18.5 g of hydroxypropylcellulose and 25 g of potato starch were mixed.
[0036]
Example 20
[0037]
Example 21
Sample 21 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to an organic powder in which 18.5 g of hydroxypropylmethylcellulose and 25 g of potato starch were mixed.
[0038]
Example 22
Sample 22 was obtained in the same manner as in Example 1, except that 37 g of methylcellulose was changed to an organic powder in which 18.5 g of hydroxypropylmethylcellulose and 25 g of onion starch were mixed.
[0039]
Example 23
Sample 23 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to an organic powder in which 25 g of potato starch and 25 g of onion starch were mixed.
[0040]
Example 24
Sample 24 was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to 1850 g of an aqueous methylcellulose solution obtained by dissolving 37 g of methylcellulose (manufactured by Wako Pure Chemical Industries) in 1813 g of water.
[0041]
Example 25
Sample 25 was obtained in the same manner as in Example 1 except that it was dried using a spray dryer (ON-16G manufactured by Okawara Chemical Co., Ltd.) set at an inlet of 500 ° C and an outlet of 250 ° C.
[0042]
Example 26
Sample 26 was obtained in the same manner as in Example 1 except that 407 g of cerium oxide and 370 g of zirconium were used.
[0043]
Comparative Example 1
750 g of cerium oxide was impregnated with an aqueous zirconium nitrate solution containing 185 g of zirconium, dried at 150 ° C. for 4 hours, and then fired at 600 ° C. for 2 hours to obtain sample a (impregnation method).
[0044]
Comparative Example 2
An aqueous cerium nitrate solution containing 611 g of cerium and an aqueous zirconium nitrate solution containing 185 g of zirconium were weighed into a container, and a 1N ammonium aqueous solution was gradually added dropwise to the pH while stirring the solution.
After the calcined reaction mass was stirred in the solution for 1 hour, solid-liquid separation was performed by filtration. The collected filtrate was then washed with 1 L of distilled water for 20 minutes and filtered again.
This operation was repeated 6 times, followed by drying at 120 ° C. for 12 hours and then baking at 300 ° C. for 12 hours to obtain Sample b (coprecipitation method). Ten lots were extracted from sample b to obtain samples b-1 to b-10.
[0045]
Comparative Example 3
Sample c was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to 60 g of glycogen.
[0046]
Comparative Example 4
A sample d was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to 60 g of a commercially available gelatin powder to which a small amount of pure water was previously added.
[0047]
Comparative Example 5
Sample e was obtained in the same manner as in Example 1 except that 37 g of methylcellulose was changed to 60 g of carboxymethylcellulose.
[0048]
Comparative Example 6
Sample f was obtained in the same manner as in Comparative Example 1 except that 500 g of cerium oxide and a zirconium nitrate solution containing 370 g of zirconium were used.
Table 1 shows the compositions and production conditions of the raw materials and additives of the above Examples and Comparative Examples.
[0049]
[Table 1]
Test Example 10 g of each sample obtained in the above examples and comparative examples was put in a magnetic crucible, put into an electric furnace in an air atmosphere, and subjected to a durability test held at 1000 ° C. for 4 hours.
Using these RAD-B models manufactured by Rigaku Corporation, the angle range in which CeO 2 (cubic) and ZrO 2 (tetragonal) peaks appear on the (111) plane is precisely measured using the RAD-B model by Rigaku Electric. did.
From the measurement results, the crystallite diameter and the lattice constant were calculated and compared from the presence / absence of a ZrO 2 (tetragonal) single peak (30.19 °), the peak top measurement angle and the full width at half maximum of the maximum peak.
[0051]
That is, the peak width at half the peak top height was set to the half width, the top position was set to 2θ, and the crystallite diameter and the lattice constant were calculated and compared as follows.
(1) Calculation method of crystallite diameter Crystallite diameter (A) = 0.9 × λ / (half width × cos (2θ / 2))
λ is a device-specific value, in this example 1.5419
(2) The lattice constant d value is calculated.
d = λ / (2 × sin θ)
For this d value, the measurement in this example is because the crystal plane is the (111) plane,
[Expression 1]
Multiply √ (1 2 +1 2 +1 2 ) to calculate the lattice constant.
Lattice constant = λ / (2 × sin θ) × √3
For Samples 1 to 26 and Samples a to f obtained in Examples and Comparative Examples, measurement peaks are shown in FIGS. 1 to 32, and presence or absence of single peaks, crystallite diameters, and lattice constants are shown in Table 2.
[0052]
[Table 2]
In FIG. 1, the main peak is between the CeO 2 single peak and the CeO 2 single peak, and is due to the Ce—Zr complex. Single peaks of CeO 2 and ZrO 2 are not observed. 2 to 26, a complex peak similar to that of Sample 1 is observed, and no single peak is observed. In FIG. 27, a separated ZrO 2 single peak is seen, in FIG. 28, no complex peak is seen as in Sample 1, and a small separated ZrO 2 single peak is seen in FIG. 29, FIGS. At 32, a separate ZrO 2 single peak is seen.
[0054]
From X-ray measurement diagram of a sample prepared by adding a cellulose derivative or starch, ZrO 2 (tetragonal) a peak is not observed, ZrO 2 (tetragonal) from the sample by the sample and glycogen or gelatin by impregnation From the lattice constants in Table 2 where peaks were observed, it can be seen that in the sample according to the example, all of Zr was combined with Ce, but in the sample according to the comparative example other than the coprecipitation method, the combination of Ce and Zr was It is not enough. That is, when the lattice constants generally reported are examined, the lattice constant of CeO 2 is 5.411 and the lattice constant of ZrO 2 is 5.213, and CeO 2 combined with Zr as in the present invention is between these. Has a peak top. When the generally reported lattice constant of CeO 2 complexed with Zr was examined, Ce 0.75 Zr 0.25 O 2 , which was the same composition as in the example, was 5.349. The lattice constants of the examples shown in Table 2 are closer to this 5.349 than that of CeO 2 of 5.411, and the comparative example is almost the same as that of CeO 2 of 5.411. However, in the comparative example except the coprecipitation method, it was judged that the complexing of Ce and Zr was insufficient.
[0055]
Table 3 shows the presence / absence of a single peak, the crystallite diameter, and the lattice constant for Samples 1-1 to 1-10 of Example 1 and Samples b-1 to b-10 of Comparative Example 2.
From Table 3, it was found that the lattice constant was less varied than that of Comparative Example 2 in which Example 1 was a coprecipitation method, and that the present invention provides better repeatability.
The examples in Table 2 were prepared by various prototypes and could not be said to be the same, so the amount of variation cannot be evaluated by comparing them.
Table 3 shows the evaluation of variation between lots using the preparation method of Sample 1. Since 3δ is smaller than Comparative Example 2 which is a coprecipitation method, the variation was judged to be small.
[0056]
[Table 3]
【The invention's effect】
According to the present invention, an organic powder or a colloid of organic powder is added to a uniform mixed solution of cerium and zirconium to form an organic linear colloid, so that the cerium and zirconium in the solution constitute a fiber structure. Since the remigration is suppressed by the high viscosity due to the linear colloid, the precursor with the separation and segregation of cerium and zirconium is obtained after the drying process. Is obtained. Therefore, according to the present invention, since cerium and zirconium can be mechanically dispersed with a small number of steps, the composite can be provided as a repeatable result.
[Brief description of the drawings]
FIG. 1 is a diagram showing an X-ray diffraction peak of Sample 1. FIG.
2 is a diagram showing an X-ray diffraction peak of Sample 2. FIG.
3 is a diagram showing an X-ray diffraction peak of Sample 3. FIG.
4 is a diagram showing an X-ray diffraction peak of Sample 4. FIG.
5 is a diagram showing an X-ray diffraction peak of Sample 5. FIG.
6 is a diagram showing an X-ray diffraction peak of Sample 6. FIG.
7 is a diagram showing an X-ray diffraction peak of Sample 7. FIG.
FIG. 8 is a diagram showing an X-ray diffraction peak of Sample 8.
9 is a diagram showing an X-ray diffraction peak of Sample 9. FIG.
10 is a diagram showing an X-ray diffraction peak of Sample 10. FIG.
11 is a diagram showing an X-ray diffraction peak of Sample 11. FIG.
12 is a diagram showing an X-ray diffraction peak of Sample 12. FIG.
13 is a diagram showing an X-ray diffraction peak of Sample 13. FIG.
14 is a diagram showing an X-ray diffraction peak of Sample 14. FIG.
15 is a diagram showing an X-ray diffraction peak of Sample 15. FIG.
16 is a diagram showing an X-ray diffraction peak of Sample 16. FIG.
17 is a diagram showing an X-ray diffraction peak of Sample 17. FIG.
18 is a diagram showing an X-ray diffraction peak of Sample 18. FIG.
19 is a diagram showing an X-ray diffraction peak of Sample 19. FIG.
20 is a diagram showing an X-ray diffraction peak of
21 is a diagram showing an X-ray diffraction peak of Sample 21. FIG.
22 is a diagram showing an X-ray diffraction peak of a sample 22. FIG.
23 is a diagram showing an X-ray diffraction peak of Sample 23. FIG.
24 is a diagram showing an X-ray diffraction peak of a sample 24. FIG.
25 is a diagram showing an X-ray diffraction peak of Sample 25. FIG.
26 is a diagram showing an X-ray diffraction peak of a sample 26. FIG.
FIG. 27 is a diagram showing an X-ray diffraction peak of sample a.
FIG. 28 is a diagram showing an X-ray diffraction peak of sample b.
FIG. 29 is a diagram showing an X-ray diffraction peak of sample c.
FIG. 30 is a diagram showing an X-ray diffraction peak of sample d.
FIG. 31 is a diagram showing an X-ray diffraction peak of a sample e.
FIG. 32 is a diagram showing an X-ray diffraction peak of sample f.
Claims (4)
Priority Applications (1)
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| JP18915195A JP3689938B2 (en) | 1995-07-25 | 1995-07-25 | Method for producing cerium-zirconium composite |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18915195A JP3689938B2 (en) | 1995-07-25 | 1995-07-25 | Method for producing cerium-zirconium composite |
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| JP3689938B2 true JP3689938B2 (en) | 2005-08-31 |
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| US20020032123A1 (en) | 2000-02-23 | 2002-03-14 | Ford Global Technologies, Inc. | Exhaust gas catalyst and method of manufacturing same |
| JP5168527B2 (en) * | 2001-01-18 | 2013-03-21 | 株式会社豊田中央研究所 | Oxide powder and production method thereof |
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