JPH10216509A - Oxygen storing cerium-based compounded oxide - Google Patents

Oxygen storing cerium-based compounded oxide

Info

Publication number
JPH10216509A
JPH10216509A JP9026851A JP2685197A JPH10216509A JP H10216509 A JPH10216509 A JP H10216509A JP 9026851 A JP9026851 A JP 9026851A JP 2685197 A JP2685197 A JP 2685197A JP H10216509 A JPH10216509 A JP H10216509A
Authority
JP
Japan
Prior art keywords
cerium
composite oxide
based composite
oxide
zirconium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP9026851A
Other languages
Japanese (ja)
Other versions
JP3429967B2 (en
Inventor
Hirohisa Tanaka
裕久 田中
Koji Yamada
浩次 山田
Mari Yamamoto
真里 山本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Daihatsu Motor Co Ltd
Original Assignee
Daihatsu Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daihatsu Motor Co Ltd filed Critical Daihatsu Motor Co Ltd
Priority to JP02685197A priority Critical patent/JP3429967B2/en
Priority to KR10-1998-0003732A priority patent/KR100455300B1/en
Priority to DE19805259A priority patent/DE19805259B4/en
Publication of JPH10216509A publication Critical patent/JPH10216509A/en
Application granted granted Critical
Publication of JP3429967B2 publication Critical patent/JP3429967B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
    • B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/0203—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of metals not provided for in B01J20/04
    • B01J20/0225—Compounds of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt
    • B01J20/0229—Compounds of Fe
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/10—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of rare earths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/83—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G25/00—Compounds of zirconium
    • C01G25/006—Compounds containing, besides zirconium, two or more other elements, with the exception of oxygen or hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/908—O2-storage component incorporated in the catalyst
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Abstract

PROBLEM TO BE SOLVED: To keep high oxygen storage capacity even in severe condition by employing an oxygen storaging cerium based compounded oxide having a specified formula for efficiently extracting the function of a catalyst to remove NOX, CO, etc., contained in an exhaust gas of an internal combustion engine of an automobile and as such. SOLUTION: As a cerium based compounded oxide whose specific surface area tends to decrease due to growth of cerium oxide at the time when the oxide is exposed to high temperature, an oxide having a prescribed formula is used (wherein R stands for rare earth metals, (z) for the oxygen deficient amount, and 0.2<=x+y<=0.9, 0.1<=x<=0.8, 0.05<=y<=0.3). In this cerium based compounded oxide, a part of cerium of cerium oxide crystal is preferably substituted with zirconium and rare earth metals and forms solid-solution, so that zirconium inhibits the mass transfer of cerium and suppresses grain growth of the cerium-based compounded oxide. Moreover, the compounded oxide is preferably used while bearing a noble metal.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本願発明は、自動車などの内
燃機関から排出される排気ガス中に含まれる窒素酸化物
（ＮＯX ）、一酸化炭素（ＣＯ）、および炭化水素（Ｈ
Ｃ）などを浄化する触媒を効率良く作用させるために用
いられる酸素吸蔵性セリウム系複合酸化物に関する。The present invention relates to the nitrogen oxides contained in the exhaust gas discharged from an internal combustion engine such as an automobile (NO X), carbon monoxide (CO), and hydrocarbon (H
The present invention relates to an oxygen-storing cerium-based composite oxide used for causing a catalyst for purifying C) or the like to act efficiently.

【０００２】[0002]

【従来の技術】自動車などの内燃機関から排出される排
気ガス中には、ＮＯX 、ＣＯ、ＨＣなどの有害物質が含
まれており、地球環境保護の観点から、これらの有害物
質の浄化についての規制が益々厳しくなってきている。
また、一方では、燃料節約の観点から、自動車のアイド
リング時や加速時を除く通常走行時においては、理論空
燃比率の混合気状態（以下「ストイキ状態」という）よ
りも燃料希薄状態（以下「リーン状態」という）で内燃
機関を作動させる制御が広く行われるようになってきて
いる。したがって、ストイキ状態のみならず、このよう
なリーン状態においても上述した有害物質を効果的に浄
化できる触媒の開発が強く望まれている。The exhaust gas discharged from an internal combustion engine such as an automobile, NO X, CO, and contains harmful substances such as HC, in view of global environmental protection, for the purification of these harmful substances Regulations are becoming increasingly strict.
On the other hand, from the viewpoint of fuel saving, during normal driving except when the vehicle is idling or accelerating, the fuel is leaner than the stoichiometric air-fuel mixture state (hereinafter referred to as “stoichiometric state”) (hereinafter “stoichiometric state”). Control for operating the internal combustion engine in a "lean state" has been widely performed. Therefore, there is a strong demand for the development of a catalyst that can effectively purify the above harmful substances not only in the stoichiometric state but also in such a lean state.

【０００３】排気ガスから上記有害物質を浄化するため
に従来から最も広く用いられている触媒としては、プラ
チナ、パラジウム、ロジウムなどの貴金属を活性物質と
した、いわゆる三元触媒がある。この三元触媒は、ＮＯ
X からＮ2 への還元反応、あるいはＣＯからＣＯ2 およ
びＨＣからＣＯ2 、Ｈ2 Ｏへの酸化反応の触媒として作
用するものである。すなわち、上記三元触媒は、酸化反
応および還元反応の両反応の触媒として作用することが
できる。The most widely used catalyst for purifying the above-mentioned harmful substances from exhaust gas is a so-called three-way catalyst using a noble metal such as platinum, palladium or rhodium as an active substance. This three-way catalyst has NO
It functions as a catalyst for the reduction reaction from X to N 2 or the oxidation reaction from CO to CO 2 and HC to CO 2 and H 2 O. That is, the three-way catalyst can act as a catalyst for both the oxidation reaction and the reduction reaction.

【０００４】そのため、上記三元触媒の活性の向上を図
るべく様々な研究がなされており、たとえば酸化セリウ
ム（ＣｅＯ2 ）が有する気相中の酸素を結晶中に吸蔵し
たり、結晶中から放出する機能、いわゆる酸素ストレー
ジ能（ＯＳＣ）に着目したものがある。すなわち、上記
酸化セリウムを三元触媒中に添加することにより気相雰
囲気の酸素濃度を調製するものであり、Ｏ2 リッチな状
態では、気相雰囲気中における過剰の酸素を酸化セリウ
ムの結晶中に吸蔵して上記三元触媒によるＮＯ X の還元
反応を促進する一方、ＣＯおよびＨＣリッチな状態で
は、気相雰囲気中に不足する酸素を結晶中から放出し、
上記三元触媒による酸化反応の効率の向上を図ろうとす
るものである。[0004] Therefore, the activity of the three-way catalyst has been improved.
Various researches have been conducted to make it possible, for example,
(CeOTwoOxygen in the gas phase contained in
Function called oxygen storage
There is one that focuses on dino (OSC). That is,
By adding cerium oxide to the three-way catalyst,
The oxygen concentration in the atmosphere is adjusted.TwoRich state
State, excess oxygen in the vapor phase
NO in the three-way catalyst XReduction
While promoting the reaction, while CO and HC rich
Releases oxygen deficient in the gas phase atmosphere from the crystal,
Attempts to improve the efficiency of the oxidation reaction by the three-way catalyst
Things.

【０００５】[0005]

【発明が解決しようとする課題】ところで、エンジン始
動直後から触媒が早く暖まり機能できるように、触媒の
搭載位置を車体床下からよりエンジンに近いマニフォー
ルド位置に変える要求が高まっている。このように、排
気ガス浄化用触媒をエンジン近くに搭載して使用する場
合には、上記触媒が９００℃以上の高温下にさらされる
こともあり、このような高温下では上記酸化セリウムが
粒成長（シンタリング）して比表面積が減少してしま
う。このように粒成長して比表面積が減少した酸化セリ
ウムは、酸素ストレージ能が低下してしまうため、上記
三元触媒の活性の向上が図れないといった不具合が生じ
る。By the way, there is an increasing demand to change the mounting position of the catalyst from under the vehicle floor to a manifold position closer to the engine so that the catalyst can warm up immediately after the engine is started. As described above, when the exhaust gas purifying catalyst is used by being mounted near the engine, the catalyst may be exposed to a high temperature of 900 ° C. or higher. (Sintering) and the specific surface area decreases. Cerium oxide having a reduced specific surface area due to grain growth has a reduced oxygen storage capacity, and thus causes a problem that the activity of the three-way catalyst cannot be improved.

【０００６】そこで、酸化セリウムにジルコニウム、ラ
ンタンなどを添加して酸化セリウムの粒成長を抑制する
ことが提案されている（特開昭６１−２６２５２１号公
報、特開昭６１−２６２５２２号公報）が、酸化セリウ
ム粒子上にジルコニウムが偏析して酸化セリウム本来の
特性が失われるなど、高温下で十分に実用に耐えうるも
のではなかった。Accordingly, it has been proposed to suppress the grain growth of cerium oxide by adding zirconium, lanthanum or the like to cerium oxide (JP-A-61-262521 and JP-A-61-262522). However, zirconium segregates on the cerium oxide particles and loses the inherent properties of cerium oxide, and thus cannot be sufficiently used for practical use at high temperatures.

【０００７】本願発明は、上記した事情のもとで考え出
されたものであって、高い酸素ストレージ能（ＯＳＣ）
を有するとともに、苛酷条件下、たとえば９００℃以上
の高温下における使用に対しても高い酸素ストレージ能
を維持することができるセリウム系複合酸化物を提供す
ることをその課題とする。The present invention has been made under the above circumstances, and has a high oxygen storage capacity (OSC).
It is another object of the present invention to provide a cerium-based composite oxide which can maintain high oxygen storage ability even under severe conditions, for example, at a high temperature of 900 ° C. or higher.

【０００８】[0008]

【発明の開示】上記の課題を解決するために、本願発明
は、一般式DISCLOSURE OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a general formula

【化２】 で表され、Ｒは希土類金属を、ｚは酸素欠陥量を示し、
０．２≦ｘ＋ｙ≦０．９、０．１≦ｘ≦０．８、０．０
５≦ｙ≦０．３である、酸素吸蔵性セリウム系複合酸化
物を提供する。Embedded image R represents a rare earth metal, z represents the amount of oxygen defects,
0.2 ≦ x + y ≦ 0.9, 0.1 ≦ x ≦ 0.8, 0.0
Provided is an oxygen-storing cerium-based composite oxide satisfying 5 ≦ y ≦ 0.3.

【０００９】また、上記セリウム系複合酸化物は、少な
くとも一部が固溶体であることが好ましい。より具体的
には、酸化セリウムの結晶中のセリウムの一部がジルコ
ニウムおよび希土類金属で置換固溶されていることが好
ましい。酸化セリウムの結晶中のセリウムをジルコニウ
ムによって置換固溶することにより、ジルコニウムがセ
リウムの物質移動を阻止してセリウム系複合酸化物が粒
成長（シンタリング）してしまうことを抑制できるから
である。Preferably, at least a part of the cerium-based composite oxide is a solid solution. More specifically, it is preferable that a part of cerium in the crystal of cerium oxide is replaced with zirconium and rare earth metal to form a solid solution. This is because by replacing cerium in the crystal of cerium oxide with zirconium and forming a solid solution, zirconium can prevent mass transfer of cerium and suppress grain growth (sintering) of the cerium-based composite oxide.

【００１０】なお、セリウム系複合酸化物においてｘで
表されるジルコニウムの原子割合は、上記のように０．
１から０．８の範囲とする。ジルコニウムは、セリウム
酸化物中のカチオンの拡散を抑制し、高温でのセリウム
系複合酸化物の粒成長を防止するが、上記ジルコニウム
の原子割合がこの範囲よりも小さい場合には、セリウム
系複合酸化物の粒成長を十分に抑制することが困難であ
り、また、上記範囲よりも大きい場合には、セリウムそ
のものの原子割合が小さくなるため、酸素吸蔵量の低下
を招くからである。この場合、より良好な効果を得るた
めには、ｘを０．３５から０．７の範囲とするのが好ま
しい。なお、このジルコニウム中には、鉱石中に通常１
〜２％含まれているハフニウム（Ｈｆ）を含有していて
も構わない。The atomic ratio of zirconium represented by x in the cerium-based composite oxide is 0.1 as described above.
The range is from 1 to 0.8. Zirconium suppresses the diffusion of cations in the cerium oxide and prevents grain growth of the cerium-based composite oxide at high temperatures. However, when the atomic ratio of zirconium is smaller than this range, the cerium-based composite oxide This is because it is difficult to sufficiently suppress the grain growth of the material, and if it is larger than the above range, the atomic ratio of cerium itself becomes small, which causes a decrease in oxygen storage capacity. In this case, in order to obtain a better effect, it is preferable that x is in the range of 0.35 to 0.7. The zirconium usually contains 1 ore in the ore.
It may contain hafnium (Hf) that is contained in up to 2%.

【００１１】さらに、酸化セリウムの結晶中のセリウム
を希土類金属によって置換固溶させるのは、セリウム系
複合酸化物の結晶構造が室温においてもホタル石型の格
子構造で安定化させることができるからである。上記し
たようにセリウム系複合酸化物における希土類金属の原
子割合はｙで表されており、０．０５から０．３の範囲
とする。上記希土類金属の原子割合がこの範囲よりも小
さい場合には、上記セリウム系複合酸化物がセリウムと
ジルコニウムとのイオン半径の相違に起因してジルコニ
ウムを含んだ酸化セリウムと、セリウムを含んだ酸化ジ
ルコニウムに２層分離して、均一なホタル石型の結晶構
造を良好に維持することが困難となる。また、上述した
範囲よりも大きい場合には、上記希土類金属が所望の複
合酸化物以外の化合物を副生してしまったり、セリウム
やジルコニウムの原子割合が相対的に小さくなりこれら
の元素が有する機能が十分に発揮できないおそれがある
からである。この場合、より良好な効果を得るために
は、ｙを０．０５から０．２の範囲とするのが好まし
い。Further, the reason why cerium in the crystal of cerium oxide is replaced with a rare earth metal to form a solid solution is because the crystal structure of the cerium-based composite oxide can be stabilized by a fluorite-type lattice structure even at room temperature. is there. As described above, the atomic ratio of the rare earth metal in the cerium-based composite oxide is represented by y, and is in the range of 0.05 to 0.3. When the atomic ratio of the rare earth metal is smaller than this range, the cerium-based composite oxide contains cerium oxide containing zirconium due to a difference in ionic radius between cerium and zirconium, and zirconium oxide containing cerium. It is difficult to maintain a uniform fluorite-type crystal structure by separating into two layers. In addition, when it is larger than the above range, the rare earth metal may produce a compound other than the desired composite oxide as a by-product, or the atomic ratio of cerium or zirconium becomes relatively small, and the function of these elements is possessed. This is because there is a possibility that the effect cannot be sufficiently exerted. In this case, in order to obtain a better effect, it is preferable that y is in the range of 0.05 to 0.2.

【００１２】なお、上記希土類金属Ｒとしては、イット
リウム、スカンジウム、ランタン、プラセオジム、ネオ
ジム、プロメチウム、サマリウム、ユウロビウム、ガド
リニウム、テルビウム、ジスプロシウム、ホルミウム、
エルビウム、ツリウム、イッテルビウム、およびルテチ
ウムが挙げられ、好ましくは、イットリウム（Ｙ）が用
いられる。また、これらの希土類金属Ｒは、単独または
２種以上併用してもよい。The rare earth metal R includes yttrium, scandium, lanthanum, praseodymium, neodymium, promethium, samarium, eurobium, gadolinium, terbium, dysprosium, holmium,
Erbium, thulium, ytterbium, and lutetium are mentioned, and preferably, yttrium (Y) is used. These rare earth metals R may be used alone or in combination of two or more.

【００１３】また、セリウム系複合酸化物におけるジル
コニウムの原子割合ｘと、希土類金属の原子割合ｙとを
加えたｘ＋ｙの範囲としては、０．２から０．９の範囲
が好適である。なお、１からｘ＋ｙを減じた値がセリウ
ム系複合酸化物におけるセリウムの原子割合である。し
たがって、セリウム系複合酸化物におけるセリウムの原
子割合１−（ｘ＋ｙ）としては、０．１から０．８の範
囲となる。セリウム系複合酸化物が酸素ストレージ能
（ＯＳＣ）を有するのは、セリウムが酸化あるいは還元
されて価数が変化するからであり、この事実を考慮すれ
ばセリウムの原子割合を余りに小さく設定すると酸化セ
リウムが本来有する酸素ストレージ能を十分に発揮させ
ることができず、また、セリウムの原子割合が小さいと
いうことは、ジルコニウムあるいは希土類金属の原子割
合が大きいということであるので、上述したように、ジ
ルコニウムの原子割合が大きい場合にはセリウム系複合
酸化物が２層分離してしまったり、希土類金属の原子割
合が大きい場合には、所望の複合酸化物以外の化合物を
副生してしまうといった不具合が生じる。逆に、セリウ
ムの原子割合が大きすぎる場合には、ジルコニウムある
いは希土類金属の原子割合が不当に小さくなってしまい
ジルコニウムあるいは希土類金属の有する本来の機能を
十分に発揮することができない。したがって、セリウム
の原子割合としては上記範囲が妥当であり、より好まし
くは０．２から０．６とする。Further, the range of x + y, which is the sum of the atomic ratio x of zirconium and the atomic ratio y of the rare earth metal in the cerium-based composite oxide, is preferably in the range of 0.2 to 0.9. The value obtained by subtracting x + y from 1 is the atomic ratio of cerium in the cerium-based composite oxide. Therefore, the atomic ratio 1- (x + y) of cerium in the cerium-based composite oxide is in the range of 0.1 to 0.8. The cerium-based composite oxide has an oxygen storage capacity (OSC) because cerium is oxidized or reduced and its valence changes. In consideration of this fact, if the atomic ratio of cerium is set too small, cerium oxide may be used. Can not fully exhibit the oxygen storage capacity originally possessed, and the fact that the atomic ratio of cerium is small means that the atomic ratio of zirconium or rare earth metal is large, so as described above, zirconium When the atomic ratio is large, the cerium-based composite oxide is separated into two layers, and when the atomic ratio of the rare earth metal is large, a compound other than the desired composite oxide is produced as a by-product. . On the other hand, if the atomic ratio of cerium is too large, the atomic ratio of zirconium or the rare earth metal becomes unduly small, and the original function of zirconium or the rare earth metal cannot be sufficiently exhibited. Therefore, the above range is appropriate for the atomic ratio of cerium, and is more preferably 0.2 to 0.6.

【００１４】さらに、セリウム系複合酸化物は、貴金
属、あるいは遷移金属を担持させて使用することが好ま
しい。セリウム系複合酸化物に担持された貴金属、ある
いは遷移金属は、自動車排ガスの酸化、還元による浄化
反応に優れた触媒作用を示すために、気相雰囲気の条件
に応じて上記セリウム系複合酸化物の酸素の吸蔵、放出
を補助する役割を果たす。すなわち、セリウム系複合酸
化物に貴金属あるいは遷移金属を担持させた場合には、
気相雰囲気の条件に応じて上記セリウム系複合酸化物が
所定量の酸素を放出して平衡に達するまでの時間を短縮
させることができる。Further, the cerium-based composite oxide is preferably used by supporting a noble metal or a transition metal. The noble metal or transition metal supported on the cerium-based composite oxide exhibits excellent catalytic action in the purification reaction by oxidation and reduction of automobile exhaust gas. It plays a role in assisting the storage and release of oxygen. That is, when a noble metal or a transition metal is supported on a cerium-based composite oxide,
The time required for the cerium-based composite oxide to release a predetermined amount of oxygen and reach equilibrium can be shortened depending on the conditions of the gaseous atmosphere.

【００１５】なお、上記貴金属としては、ルテニウム
（Ｒｕ）、ロジウム（Ｒｈ）、パラジウム（Ｐｄ）、銀
（Ａｇ）、オスミウム（Ｏｓ）、イリジウム（Ｉｒ）、
白金（Ｐｔ）、および金（Ａｕ）が用いられるが、好ま
しくは、ロジウム、パラジウムが用いられ、上記遷移金
属としては鉄（Ｆｅ）、コバルト（Ｃｏ）、ニッケル
（Ｎｉ）、銅（Ｃｕ）からなる群のうちの少なくとも１
つを選択することが好ましく、より好ましくは、鉄（Ｆ
ｅ）が用いられる。また、これらの貴金属、あるいは遷
移金属をセリウム系複合酸化物に担持させる方法として
は公知の方法が採用される。The noble metals include ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), osmium (Os), iridium (Ir),
Platinum (Pt) and gold (Au) are used, and preferably, rhodium and palladium are used, and the transition metal is selected from iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu). At least one of the group
Preferably, one is selected, more preferably, iron (F
e) is used. In addition, as a method of supporting these noble metals or transition metals on the cerium-based composite oxide, a known method is employed.

【００１６】本願発明のセリウム系複合酸化物は、公知
の方法を用いて調製することができ、たとえば炭酸セリ
ウム粉末に水を加えてスラリーとした後、このスラリー
にジルコニウム塩および希土類金属塩を所定の化学量論
比で混合した水溶液を加えて、十分に攪拌した後、熱処
理を行い本願発明のセリウム系複合酸化物を得る。The cerium-based composite oxide of the present invention can be prepared by a known method. For example, water is added to cerium carbonate powder to form a slurry, and a zirconium salt and a rare earth metal salt are added to the slurry in a predetermined manner. The cerium-based composite oxide of the present invention is obtained by adding an aqueous solution mixed at a stoichiometric ratio of 1 and stirring sufficiently, followed by heat treatment.

【００１７】炭酸セリウム粉末は、市販の何れのもので
あってもよいが、酸素ストレージ能を高めるため比表面
積の大きなものが好ましく、結晶粒径が０．１μｍ以下
のものが好適である。この炭酸セリウム粉末１重量部に
約１０〜５０重量部の水を加えてスラリーとする。The cerium carbonate powder may be any commercially available one, but preferably has a large specific surface area in order to enhance the oxygen storage capacity, and preferably has a crystal grain size of 0.1 μm or less. About 10 to 50 parts by weight of water is added to 1 part by weight of the cerium carbonate powder to form a slurry.

【００１８】ジルコニウム塩としては、オキシ塩化ジル
コニウム、オキシ硝酸ジルコニウム、オキシ硫酸ジルコ
ニウムなどの無機塩の他、オキシ酢酸ジルコニウムなど
の有機塩が挙げられ、好ましくは、オキシ硝酸ジルコニ
ウムが用いられる。希土類金属塩としては、硫酸塩、硝
酸塩、塩酸塩、リン酸塩などの無機塩、酢酸塩、シュウ
酸塩などの有機塩が挙げられ、好ましくは、硝酸塩が用
いられる。これらのジルコニウム塩および希土類金属塩
は、化学量論比で上記した所定の原子割合の範囲となる
割合でそれぞれ１重量部に対して０．１から１０重量部
の水に溶解し混合水溶液とする。Examples of the zirconium salt include inorganic salts such as zirconium oxychloride, zirconium oxynitrate, and zirconium oxysulfate, and organic salts such as zirconium oxyacetate. Preferably, zirconium oxynitrate is used. Examples of the rare earth metal salts include inorganic salts such as sulfates, nitrates, hydrochlorides, and phosphates, and organic salts such as acetates and oxalates. Preferably, nitrates are used. These zirconium salts and rare earth metal salts are each dissolved in 0.1 to 10 parts by weight of water with respect to 1 part by weight at a stoichiometric ratio within the above-mentioned predetermined atomic ratio to form a mixed aqueous solution. .

【００１９】この混合水溶液を上記スラリーに加えて十
分に攪拌混合した後、熱処理を行う。この熱処理は、先
ず、真空乾燥機などを用いて減圧乾燥を行った後、好ま
しくは、約５０℃〜２００℃で約１〜４８時間乾燥し乾
燥物を得、得られた乾燥物を約３５０℃〜１０００℃、
好ましくは、約４００℃〜７００℃で約１〜１２時間、
好ましくは約２〜４時間焼成することにより行う。この
焼成において、好ましくは、複合酸化物の少なくとも一
部が固溶体となるようにして、複合酸化物の耐熱性を高
める。固溶体を形成させる好適な焼成条件は、セリウム
系複合酸化物の組成およびその割合にて適宜決定され
る。After the mixed aqueous solution is added to the slurry and sufficiently stirred and mixed, heat treatment is performed. In this heat treatment, first, after drying under reduced pressure using a vacuum dryer or the like, preferably, the dried product is dried at about 50 ° C. to 200 ° C. for about 1 to 48 hours to obtain a dried product. ℃ ~ 1000 ℃,
Preferably, at about 400 ° C. to 700 ° C. for about 1 to 12 hours,
The firing is preferably performed for about 2 to 4 hours. In this firing, preferably, at least a part of the composite oxide becomes a solid solution to enhance the heat resistance of the composite oxide. Suitable firing conditions for forming a solid solution are appropriately determined by the composition of the cerium-based composite oxide and its ratio.

【００２０】また、本願発明のセリウム系複合酸化物
は、所定の化学量論比となるようにセリウム、ジルコニ
ウム、および希土類金属を含む塩の溶液を調製して、こ
の溶液にアルカリ性水溶液、あるいは有機酸を加え、セ
リウム、ジルコニウム、および希土類金属を含む塩を共
沈させた後、この共沈物を酸化処理するか、あるいはセ
リウム、ジルコニウム、および希土類金属を含む混合ア
ルコキシド溶液を調製して、この混合アルコキシド溶液
に脱イオン水を加えて、共沈あるいは加水分解させて、
この共沈物あるいは加水分解生成物を熱処理してもよ
い。The cerium-based composite oxide of the present invention is prepared by preparing a salt solution containing cerium, zirconium and a rare earth metal in a predetermined stoichiometric ratio, and adding an alkaline aqueous solution or an organic solution to the solution. After adding an acid and coprecipitating a salt containing cerium, zirconium, and a rare earth metal, the coprecipitate is subjected to an oxidation treatment, or a mixed alkoxide solution containing cerium, zirconium, and a rare earth metal is prepared. Add deionized water to the mixed alkoxide solution, coprecipitate or hydrolyze,
This coprecipitate or hydrolysis product may be heat-treated.

【００２１】この場合、用いる塩としては、セリウム
塩、ジルコニウム塩および希土類金属塩の塩としての上
記例示の塩を用い、アルカリ水溶液としては、アンモニ
ア、炭酸アンモンなどが用いられ、有機酸としては、シ
ュウ酸、クエン酸などが用いられる。In this case, as the salt to be used, the above-mentioned salts as salts of cerium salt, zirconium salt and rare earth metal salt are used. As the alkaline aqueous solution, ammonia, ammonium carbonate or the like is used. As the organic acid, Oxalic acid, citric acid and the like are used.

【００２２】一方、混合アルコキシド溶液のアルコキシ
ドとしては、セリウム、ジルコニウム、および希土類金
属のメトキシド、エトキシド、プロポキシド、ブトキシ
ドなどやこれらのエチレンオキサイド付加物などが用い
られる。On the other hand, as the alkoxide of the mixed alkoxide solution, cerium, zirconium and rare earth metal methoxide, ethoxide, propoxide, butoxide and the like and ethylene oxide adducts thereof are used.

【００２３】また、得られた共沈物あるいは加水分解生
成物を熱処理する場合は、これら共沈物あるいは加水分
解生成物を濾過洗浄後、好ましくは約５０℃〜２００℃
で約１〜４８時間乾燥し乾燥物を得、得られた乾燥物を
約３５０℃〜１０００℃、好ましくは、４００℃〜７０
０℃で約１〜１２時間、好ましくは、約２〜４時間焼成
することにより行う。この焼成において、好ましくは、
複合酸化物の少なくとも一部が固溶体となるようにし
て、複合酸化物の耐酸化性を高める。好適な焼成条件
は、複合酸化物の組成およびその割合にて適宜決定され
る。When the obtained coprecipitate or hydrolysis product is subjected to a heat treatment, the coprecipitate or hydrolysis product is filtered and washed, preferably at about 50 ° C. to 200 ° C.
For about 1 to 48 hours to obtain a dried product, and the obtained dried product is dried at about 350 ° C to 1000 ° C, preferably 400 ° C to 70 ° C.
The calcination is carried out at 0 ° C. for about 1 to 12 hours, preferably for about 2 to 4 hours. In this firing, preferably,
The oxidation resistance of the composite oxide is increased by making at least a part of the composite oxide into a solid solution. Suitable firing conditions are appropriately determined by the composition of the composite oxide and its ratio.

【００２４】このようにして得られた本願発明のセリウ
ム系複合酸化物は、さらに貴金属および／または遷移金
属を担持させることにより効率の向上が図られる。The efficiency of the thus obtained cerium-based composite oxide of the present invention can be improved by further supporting a noble metal and / or a transition metal.

【００２５】上記貴金属としては、上述したようにルテ
ニウム、ロジウム、パラジウム、オスミウム、イリジウ
ム、および白金からなる白金族元素が挙げられ、好まし
くは、ロジウム、パラジウムが用いられる。As described above, the noble metal includes a platinum group element composed of ruthenium, rhodium, palladium, osmium, iridium and platinum, and preferably rhodium and palladium are used.

【００２６】上記遷移元素としては、好ましくはＦｅ、
Ｃｏ、Ｎｉ、およびＣｕなどが挙げられる。As the transition element, preferably, Fe,
Co, Ni, Cu and the like.

【００２７】上記貴金属または遷移元素を複合酸化物に
担持させる方法は、公知のいずれの方法であってもよ
く、たとえば、貴金属または遷移元素を含む塩の溶液を
調製し、この含塩溶液を複合酸化物に含侵することによ
り行う。この場合、含塩溶液としては、上記に例示のい
ずれの塩の溶液を用いてもよく、また実用的には、硝酸
塩水溶液、ジニトロジアンミン硝酸塩溶液、塩化物水溶
液などが用いられる。含塩溶液は、約１〜２０重量％の
貴金属塩または遷移金属塩を含み、複合酸化物に含侵さ
せた後は、好ましくは、約５０℃〜２００℃で約１〜４
８時間乾燥し、さらに約３５０℃〜１０００℃で約１〜
１２時間焼成して担持させることにより行われる。The method of supporting the noble metal or the transition element on the composite oxide may be any known method. For example, a solution of a salt containing the noble metal or the transition element is prepared, and this salt-containing solution is mixed. This is performed by impregnating the oxide. In this case, as the salt-containing solution, a solution of any of the above-mentioned salts may be used, and practically, a nitrate aqueous solution, a dinitrodiammine nitrate solution, a chloride aqueous solution, or the like is used. The salt-containing solution contains about 1 to 20% by weight of a noble metal salt or a transition metal salt, and after impregnating the composite oxide, preferably at about 50 ° C to 200 ° C for about 1 to 4%.
Dried for 8 hours, and further at about 350 ° C to 1000 ° C for about 1 to
It is carried out by firing for 12 hours to carry it.

【００２８】また、他の方法としては、上記した複合酸
化物の製造工程において、セリウム、ジルコニウムおよ
び希土類金属を含む塩の溶液や混合アルコキシド溶液を
共沈あるいは加水分解する際に、貴金属または遷移元素
を含む塩の溶液を加えて、複合酸化物の各成分とともに
貴金属または遷移元素を共沈させて、しかる後に熱処理
を行う方法が挙げられる。この場合に使用される貴金属
塩の溶液としては、硝酸塩水溶液、ジニロトジアンミン
硝酸溶液、塩化物溶液などの上記記載の含塩溶液などが
挙げられる。具体的には、パラジウム塩溶液としては、
硝酸パラジウム、ジニロトジアンミンパラジウム硝酸塩
溶液、４価パラジウムアンミン硝酸溶液、ロジウム塩溶
液としては、硝酸ロジウム溶液、塩化ロジウム溶液など
が用いられる。遷移元素塩の溶液としては、好ましくは
硝酸塩が用いられ、たとえば硝酸鉄、硝酸コバルト、硝
酸ニッケル、硝酸銅などが用いられる。As another method, a precious metal or a transition element may be used when co-precipitating or hydrolyzing a solution of a salt containing cerium, zirconium and a rare earth metal or a mixed alkoxide solution in the above-mentioned composite oxide production step. Is added, and a noble metal or a transition element is co-precipitated with each component of the composite oxide, followed by heat treatment. Examples of the solution of the noble metal salt used in this case include the above-mentioned salt-containing solutions such as an aqueous nitrate solution, a dinilotodiamine nitric acid solution, and a chloride solution. Specifically, as the palladium salt solution,
As the palladium nitrate, dinilotodiamine palladium nitrate solution, tetravalent palladium ammine nitrate solution, and rhodium salt solution, rhodium nitrate solution, rhodium chloride solution and the like are used. As the solution of the transition element salt, nitrate is preferably used, for example, iron nitrate, cobalt nitrate, nickel nitrate, copper nitrate and the like are used.

【００２９】次いで行われる得られた共沈物の熱処理
は、真空乾燥機などを用いて減圧乾燥を行った後、好ま
しくは、約５０℃〜２００℃で約１〜４８時間乾燥して
得、得られた乾燥物を約３５０℃〜１０００℃で約１〜
１２時間、好ましくは４００℃〜７００℃で約１〜 １
２時間、好ましくは約２〜４時間焼成することにより行
われる。The subsequent heat treatment of the obtained coprecipitate is preferably performed by drying under reduced pressure using a vacuum dryer or the like, and preferably by drying at about 50 ° C. to 200 ° C. for about 1 to 48 hours. The obtained dried product is heated at about 350 ° C. to 1000 ° C. for about 1 to about 1 hour.
12 hours, preferably at 400 ° C to 700 ° C for about 1 to 1
It is performed by firing for 2 hours, preferably for about 2 to 4 hours.

【００３０】[0030]

【発明の実施の形態】次に、本願発明の実施例を比較例
とともに説明する。Next, examples of the present invention will be described together with comparative examples.

【００３１】[0031]

【実施例１】本実施例においては、組成がＣｅ0.6 Ｚｒ
0.30Ｙ0.10Ｏ1.95/0.5wt％Ｆｅのセリウム系複合酸化物
を用いて、このセリウム系複合酸化物が有する初期の酸
素ストレージ能と、高温下における酸化還元耐久試験
（エージング）を行った後の酸素ストレージ能とを比較
することにより、上記セリウム系複合酸化物の苛酷条件
下での耐久性（変化率）を評価した。この結果を表１に
示した。なお、上記セリウム系複合酸化物の組成におい
て、『/0.5wt％Ｆｅ』と表現されている部分は、Ｆｅ
（鉄）を含まないセリウム系複合酸化物の重量に対して
０．５重量％に相当する重量のＦｅが担持されているこ
とを表している。Embodiment 1 In this embodiment, the composition is Ce 0.6 Zr
Using a cerium-based composite oxide of 0.30 Y 0.10 O 1.95 / 0.5 wt% Fe, an initial oxygen storage capacity of the cerium-based composite oxide and an oxidation-reduction durability test (aging) at a high temperature are performed. The durability (change rate) of the cerium-based composite oxide under severe conditions was evaluated by comparing the oxygen storage capacity with the oxygen storage capacity. The results are shown in Table 1. In the composition of the cerium-based composite oxide, the portion expressed as “/0.5 wt% Fe” is Fe Fe
This indicates that Fe of a weight equivalent to 0.5% by weight with respect to the weight of the cerium-based composite oxide not containing (iron) is supported.

【００３２】（セリウム系複合酸化物の調製）上記組成
のセリウム系複合酸化物は、いわゆるアルコキシド法に
より調製した。先ず、セリウムイソプロポキシド３８．
４ｇ（０．１０２ｍｏｌ）、ジルコニウムイソプロポキ
シド１６．７ｇ（０．０５１ｍｏｌ）、イットリウムイ
ソプロポキシド４．５ｇ（０．０１７ｍｏｌ）をトルエ
ン２００ｍｌに溶解させ、混合アルコキシド溶液を調製
した。そして、この混合アルコキシド溶液中を脱イオン
水６００ｍｌ中に約１０分間を要して滴下してアルコキ
シドの加水分解を行った。さらに、加水分解された溶液
から溶剤およびＨ2 Ｏを留去・蒸発乾固して前駆体を作
製し、この前駆体を６０℃で２４時間通風乾燥した後
に、電気炉にて４５０℃で３時間熱処理してＣｅ0.6 Ｚ
ｒ0.30Ｙ0.10Ｏ1.95の組成を有するセリウム系複合酸化
物の粉末を得た。この酸化物の粉末２０．０ｇに脱イオ
ン水２０ｍｌを加えてスラリー状とした。さらに、硝酸
第二鉄の試薬（鉄含有量は１３．８ｗｔ％）０．７３ｇ
を脱イオン水２０ｍｌに溶解させ鉄含有量１．０ｗｔ％
を得、上記スラリーに加えて均一に混合した後にＨ2 Ｏ
を留去・蒸発乾固した。このようにして得られた粉末を
を６０℃で２４時間通風乾燥した後に、電気炉にて４５
０℃で３時間熱処理してＣｅ0.6 Ｚｒ0.30Ｙ0.10Ｏ1.95
/0.5wt％Ｆｅの組成を有するセリウム系複合酸化物を得
た。(Preparation of cerium-based composite oxide) The cerium-based composite oxide having the above composition was prepared by a so-called alkoxide method. First, cerium isopropoxide.
4 g (0.102 mol), 16.7 g (0.051 mol) of zirconium isopropoxide and 4.5 g (0.017 mol) of yttrium isopropoxide were dissolved in 200 ml of toluene to prepare a mixed alkoxide solution. The mixed alkoxide solution was dropped into 600 ml of deionized water over about 10 minutes to hydrolyze the alkoxide. Further, the solvent and H 2 O were distilled off from the hydrolyzed solution and evaporated to dryness to prepare a precursor. The precursor was air-dried at 60 ° C. for 24 hours, and then dried at 450 ° C. in an electric furnace. Heat treated for Ce 0.6 Z
A powder of a cerium-based composite oxide having a composition of r 0.30 Y 0.10 O 1.95 was obtained. 20 ml of deionized water was added to 20.0 g of this oxide powder to form a slurry. Further, 0.73 g of ferric nitrate reagent (iron content is 13.8 wt%)
Is dissolved in 20 ml of deionized water and the iron content is 1.0 wt%.
H 2 O
Was evaporated and evaporated to dryness. The powder thus obtained was air-dried at 60 ° C. for 24 hours, and then dried in an electric furnace.
Heat treated at 0 ° C. for 3 hours, Ce 0.6 Zr 0.30 Y 0.10 O 1.95
A cerium-based composite oxide having a composition of /0.5wt%Fe was obtained.

【００３３】（初期の酸素ストレージ能の評価）上記の
ようにして調製されたセリウム系複合酸化物の粉末を試
料として約１８ｍｇ採取し、５０％酸素（残部は窒素）
気流中、５００℃で１５分間保持した後、更に５００℃
にて２０％水素（残部は窒素）と５０％酸素（残部は窒
素）を交互に流し、この酸化・還元を１サイクルとして
３サイクル程度繰り返してセリウム系複合酸化物の酸素
吸蔵放出能を測定した。このときの試料の重量を経時的
に熱天秤によって測定してチャートに表した。そして、
チャート波形が最も安定している酸化・還元サイクルを
もとにして、酸化終了時の重量と還元終了時の重量との
差を計算し、この値を上記試料が吸蔵あるいは放出可能
な酸素重量として見積もった。さらに、上記酸素重量お
よび上記試料の重量をもとにして１ｍｏｌのセリウム系
複合酸化物が吸蔵あるいは放出可能な酸素のｍｏｌ数を
計算し、この値を酸素ストレージ能とした。(Evaluation of Initial Oxygen Storage Capacity) About 18 mg of the cerium-based composite oxide powder prepared as described above was sampled, and 50% oxygen (the balance was nitrogen).
After holding at 500 ° C for 15 minutes in air stream,
, 20% hydrogen (remaining nitrogen) and 50% oxygen (remaining nitrogen) were alternately flowed, and this oxidation / reduction was repeated as one cycle for about three cycles to measure the oxygen storage / release capacity of the cerium-based composite oxide. . At this time, the weight of the sample was measured with a thermobalance over time and represented in a chart. And
Based on the oxidation / reduction cycle in which the chart waveform is most stable, calculate the difference between the weight at the end of oxidation and the weight at the end of reduction, and use this value as the weight of oxygen that the sample can absorb or release. Estimated. Further, based on the weight of the oxygen and the weight of the sample, the number of moles of oxygen that can be inserted or released by 1 mol of the cerium-based composite oxide was calculated, and this value was used as the oxygen storage capacity.

【００３４】（酸化還元耐久試験）この酸化還元耐久試
験（エージング）は、実際の自動車の排気ガスの変化状
態を単純モデル化したガス流中にセリウム系複合酸化物
をさらすことによりセリウム系複合酸化物の耐久性を評
価するために行う試験である。具体的には、不活性ガス
中に５分間（パージ）、酸化ガス中に１０分間、不活性
ガス中に５分間（パージ）、還元ガス中に１０分間を１
サイクルとして４サイクルの合計２時間、試料（初期安
定化済み）をガス流中に保持した。上記不活性ガスは８
容量％のＣＯ 2 を含み残りがＮ2 であり、上記酸化ガス
は１容量％のＯ2 および８容量％のＣＯ2 を含み残りが
Ｎ2 であり、上記還元ガスは１．５容量％のＣＯおよび
０．５容量％のＨ2 を含み残りがＮ2 である。なお、上
記した何れの組成のガスにも、ガス総量の１０容量％に
相当する量の水分（水蒸気）を加えた。また、上記した
何れの組成のガスも温度を１０００℃に設定した。(Oxidation reduction endurance test)
(Aging) is the actual change in vehicle exhaust gas
Cerium-based composite oxide in a gas stream whose state is simply modeled
The durability of the cerium-based composite oxide
This is a test performed to evaluate Specifically, an inert gas
5 minutes in (purge), 10 minutes in oxidizing gas, inert
5 minutes in gas (purge), 1 minute in reducing gas for 10 minutes
Samples (initial safety)
) Was kept in the gas stream. The inert gas is 8
% CO by volume TwoAnd the rest is NTwoAnd the above oxidizing gas
Is 1% by volume of OTwoAnd 8% by volume COTwoIncluding the rest
NTwoWherein the reducing gas is 1.5% by volume of CO and
0.5% by volume of HTwoAnd the rest is NTwoIt is. In addition, above
10% by volume of the total gas is added to any of the listed gases.
A corresponding amount of water (steam) was added. Also mentioned above
The temperature of each gas was set at 1000 ° C.

【００３５】（耐久試験後の酸素ストレージ能の評価）
上記した酸化還元試験後の試料を初期の酸素ストレージ
能の評価と同様に５００℃における酸化・還元を繰り返
し、熱天秤によって測定された重量の経時変化を示す波
形が安定した酸化・還元サイクルの酸化終了時の重量と
還元終了時の重量との差を計算した。さらに、この値を
もとにして初期の酸素ストレージ能の評価と同様の手法
によって耐久試験後の酸素ストレージ能を評価した。(Evaluation of oxygen storage capacity after endurance test)
The sample after the above-described oxidation-reduction test was repeatedly oxidized and reduced at 500 ° C. in the same manner as in the initial evaluation of the oxygen storage capacity, and the oxidation / reduction cycle oxidation in which the time-dependent change in weight measured by a thermobalance was stable was observed. The difference between the weight at the end and the weight at the end of the reduction was calculated. Further, based on this value, the oxygen storage capacity after the durability test was evaluated by the same method as the evaluation of the initial oxygen storage capacity.

【００３６】（変化率の評価）表１における変化率は、
以下の式によって計算される。(Evaluation of rate of change)
It is calculated by the following formula.

【００３７】[0037]

【数１】 (Equation 1)

【００３８】すなわち、変化率とは初期の酸素ストレー
ジ能に対する耐久試験後の上記セリウム系複合酸化物の
酸素ストレージ能の劣化率を表す指標である。That is, the rate of change is an index indicating the rate of deterioration of the oxygen storage capacity of the cerium-based composite oxide after the durability test with respect to the initial oxygen storage capacity.

【００３９】[0039]

【実施例２】セリウム系複合酸化物としてＣｅ0.50Ｚｒ
0.375 Ｙ0.125 Ｏ1.9375/0.5wt％Ｆｅの組成を有するも
のを用いた点を除き、実施例１と同様の操作を行い、セ
リウム系複合酸化物が有する初期、耐久試験後の酸素ス
トレージ能の評価、および耐久試験の前後における上記
セリウム系複合酸化物の酸素ストレージ能の変化率（劣
化率）の評価を行った。このときの結果を表１に示し
た。なお、上記セリウム系複合酸化物は、実施例１と同
様の方法によって調製した。ただし、複合酸化物の状態
においてセリウム、ジルコニウムおよびイットリウムが
所定の量論比で複合酸化物を形成するように実施例１と
は異なった比率でセリウムイソプロポキシド、ジルコニ
ウムイソプロポキシド、イットリウムイソプロポキシド
を混合してトルエンに溶解させて混合アルコキシド溶液
を作製し、また、所定量のＦｅ（鉄）が含有されるよう
にＣｅ0.50Ｚｒ0.375 Ｙ0.125 Ｏ1.9375粉末を含むスラ
リーに含有する硝酸第二鉄溶液（鉄含有量は１．０ｗｔ
％）の重量を調整した。Example 2 Ce 0.50 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was carried out in the same manner as in Example 1, except that the one having the composition of 0.375 Y 0.125 O 1.9375 /0.5 wt % Fe was used. Then, the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the state of the composite oxide, cerium, zirconium, and yttrium form a composite oxide at a predetermined stoichiometric ratio. The ratio of cerium isopropoxide, zirconium isopropoxide, and yttrium isopropoxide is different from that in Example 1. The mixed alkoxide solution is prepared by mixing and dissolving in toluene, and the nitric acid contained in the slurry containing the Ce 0.50 Zr 0.375 Y 0.125 O 1.9375 powder so as to contain a predetermined amount of Fe (iron). Iron solution (iron content is 1.0wt
%) Was adjusted.

【００４０】[0040]

【実施例３】セリウム系複合酸化物としてＣｅ0.40Ｚｒ
0.45Ｙ0.15Ｏ1.925/ 0.4wt％Ｃｏの組成を有するものを
用いた点を除き、実施例１と同様の操作を行い、セリウ
ム系複合酸化物が有する初期、耐久試験後の酸素ストレ
ージ能の評価、および耐久試験の前後における上記セリ
ウム系複合酸化物の酸素ストレージ能の変化率（劣化
率）の評価を行った。このときの結果を表１に示した。
なお、上記セリウム系複合酸化物は、実施例１と同様の
方法によって調製した。ただし、複合酸化物の状態にお
いてセリウム、ジルコニウムおよびイットリウムが所定
の量論比で複合酸化物を形成するように実施例１とは異
なった比率でセリウムイソプロポキシド、ジルコニウム
イソプロポキシド、イットリウムイソプロポキシドを混
合してトルエンに溶解させて混合アルコキシド溶液を作
製し、また、所定量のＣｏ（コバルト）が含有されるよ
うにＣｅ0.40Ｚｒ0.45Ｙ0.15Ｏ1.925 粉末を含むスラリ
ーに混合する硝酸第一コバルト溶液（コバルト含有量は
１．０ｗｔ％）の重量を調整した。Embodiment 3 Ce 0.40 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the durability test was performed in the same manner as in Example 1 except that the one having a composition of 0.45 Y 0.15 O 1.925 / 0.4 wt% Co was used. Then, the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test was evaluated. Table 1 shows the results.
The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the state of the composite oxide, cerium, zirconium, and yttrium form a composite oxide at a predetermined stoichiometric ratio. The ratio of cerium isopropoxide, zirconium isopropoxide, and yttrium isopropoxide is different from that in Example 1. A mixed alkoxide solution is prepared by mixing and dissolving in a toluene solution, and a nitric acid mixture is added to a slurry containing Ce 0.40 Zr 0.45 Y 0.15 O 1.925 powder so that a predetermined amount of Co (cobalt) is contained. The weight of the cobalt solution (cobalt content was 1.0 wt%) was adjusted.

【００４１】[0041]

【実施例４】セリウム系複合酸化物としてＣｅ0.20Ｚｒ
0.60Ｙ0.20Ｏ1.90/0.7wt％Ｎｉの組成を有するものを用
いた点を除き、実施例１と同様の操作を行い、セリウム
系複合酸化物が有する初期、耐久試験後の酸素ストレー
ジ能の評価、および耐久試験の前後における上記セリウ
ム系複合酸化物の酸素ストレージ能の変化率（劣化率）
の評価を行った。このときの結果を表１に示した。な
お、上記セリウム系複合酸化物は、実施例１と同様の方
法によって調製した。ただし、複合酸化物の状態におい
てセリウム、ジルコニウムおよびイットリウムが所定の
量論比で複合酸化物を形成するように実施例１とは異な
った比率でセリウムイソプロポキシド、ジルコニウムイ
ソプロポキシド、イットリウムイソプロポキシドを混合
してトルエンに溶解させて混合アルコキシド溶液を作製
し、また、所定量のＮｉ（ニッケル）が含有されるよう
にＣｅ0.20Ｚｒ0.60Ｙ0.20Ｏ1.90粉末を含むスラリーに
混合する硝酸ニッケル溶液（ニッケル含有量は１．０ｗ
ｔ％）の重量を調整した。Embodiment 4 Ce 0.20 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the durability test was performed in the same manner as in Example 1 except that the one having a composition of 0.60 Y 0.20 O 1.90 /0.7 wt% Ni was used. And the rate of change (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test
Was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the composite oxide state, cerium, zirconium and yttrium form a composite oxide at a predetermined stoichiometric ratio, but in a different ratio from that of Example 1, cerium isopropoxide, zirconium isopropoxide, yttrium isopropoxy. A mixed alkoxide solution by mixing and dissolving it in toluene, and a nickel nitrate solution mixed with a slurry containing Ce 0.20 Zr 0.60 Y 0.20 O 1.90 powder so that a predetermined amount of Ni (nickel) is contained. (The nickel content is 1.0w
t%).

【００４２】[0042]

【実施例５】セリウム系複合酸化物としてＣｅ0.50Ｚｒ
0.375 Ｙ0.125 Ｏ1.9375/1.0wt％Ｃｕの組成を有するも
のを用いた点を除き、実施例１と同様の操作を行い、セ
リウム系複合酸化物が有する初期、耐久試験後の酸素ス
トレージ能の評価、および耐久試験の前後における上記
セリウム系複合酸化物の酸素ストレージ能の変化率（劣
化率）の評価を行った。このときの結果を表１に示し
た。なお、上記セリウム系複合酸化物は、実施例１と同
様の方法によって調製した。ただし、複合酸化物の状態
においてセリウム、ジルコニウムおよびイットリウムが
所定の量論比で複合酸化物を形成するように実施例１と
は異なった比率でセリウムイソプロポキシド、ジルコニ
ウムイソプロポキシド、イットリウムイソプロポキシド
を混合してトルエンに溶解させて混合アルコキシド溶液
を作製し、また、所定量のＣｕ（銅）が含有されるよう
にＣｅ0.50Ｚｒ0.375 Ｙ0.125 Ｏ1.9375粉末を含むスラ
リーに混合する硝酸第二銅溶液（銅含有量は１．０ｗｔ
％）の重量を調整した。Embodiment 5 Ce 0.50 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was carried out in the same manner as in Example 1, except that the one having a composition of 0.375 Y 0.125 O 1.9375 /1.0 wt % Cu was used. Then, the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the composite oxide state, cerium, zirconium and yttrium form a composite oxide at a predetermined stoichiometric ratio, but in a different ratio from that of Example 1, cerium isopropoxide, zirconium isopropoxide, yttrium isopropoxy. And mixed with toluene to prepare a mixed alkoxide solution, and mixed with a slurry containing Ce 0.50 Zr 0.375 Y 0.125 O 1.9375 powder so that a predetermined amount of Cu (copper) is contained. Copper solution (copper content is 1.0wt
%) Was adjusted.

【００４３】[0043]

【実施例６】セリウム系複合酸化物としてＣｅ0.60Ｚｒ
0.30Ｙ0.10Ｏ1.95/0.1wt％Ｒｈの組成を有するものを用
いた点を除き、実施例１と同様の操作を行い、セリウム
系複合酸化物が有する初期、耐久試験後の酸素ストレー
ジ能の評価、および耐久試験の前後における上記セリウ
ム系複合酸化物の酸素ストレージ能の変化率（劣化率）
の評価を行った。このときの結果を表１に示した。な
お、上記セリウム系複合酸化物は、実施例１と同様の方
法によって調製した。更に、所定量のＲｈ（ロジウム）
が担持されるようにＣｅ0.60Ｚｒ0.30Ｙ0.10Ｏ1.95粉末
を含むスラリーに混合する硝酸ロジウム溶液（ロジウム
含有量は０．９８０ｗｔ％）の重量を調整した。Embodiment 6 Ce 0.60 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was carried out in the same manner as in Example 1, except that a material having a composition of 0.30 Y 0.10 O 1.95 / 0.1 wt% Rh was used. And the rate of change (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test
Was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. Furthermore, a predetermined amount of Rh (rhodium)
The weight of the rhodium nitrate solution (rhodium content is 0.980 wt%) mixed with the slurry containing the Ce 0.60 Zr 0.30 Y 0.10 O 1.95 powder was adjusted so that is supported.

【００４４】[0044]

【実施例７】セリウム系複合酸化物としてＣｅ0.40Ｚｒ
0.45Ｙ0.15Ｏ1.925 /0.1wt％Ｒｈの組成を有するものを
用いた点を除き、実施例１と同様の操作を行い、セリウ
ム系複合酸化物が有する初期、耐久試験後の酸素ストレ
ージ能の評価、および耐久試験の前後における上記セリ
ウム系複合酸化物の酸素ストレージ能の変化率（劣化
率）の評価を行った。このときの結果を表１に示した。
なお、上記セリウム系複合酸化物は、実施例１と同様の
方法によって調製した。ただし、複合酸化物の状態にお
いてセリウム、ジルコニウムおよびイットリウムが所定
の量論比で複合酸化物を形成するように実施例１とは異
なった比率でセリウムイソプロポキシド、ジルコニウム
イソプロポキシド、イットリウムイソプロポキシドを混
合してトルエンに溶解させて混合アルコキシド溶液を作
製し、また、所定量のＲｈ（ロジウム）が担持されるよ
うにＣｅ0.40Ｚｒ0.45Ｙ0.15Ｏ1.925 粉末を含むスラリ
ーに混合する硝酸ロジウム溶液（ロジウム含有量は０．
９８０ｗｔ％）の重量を調整した。Embodiment 7 Ce 0.40 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was performed in the same manner as in Example 1, except that a compound having a composition of 0.45 Y 0.15 O 1.925 / 0.1 wt % Rh was used. Then, the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test was evaluated. Table 1 shows the results.
The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the state of the composite oxide, cerium, zirconium, and yttrium form a composite oxide at a predetermined stoichiometric ratio. The ratio of cerium isopropoxide, zirconium isopropoxide, and yttrium isopropoxide is different from that in Example 1. rhodium nitrate solution were mixed de prepare a mixed alkoxide solution dissolved in toluene, and a predetermined amount of Rh (rhodium) is mixed into a slurry containing a Ce 0.40 Zr 0.45 Y 0.15 O 1.925 powder as carried (Rhodium content is 0.
980 wt%).

【００４５】[0045]

【実施例８】セリウム系複合酸化物としてＣｅ0.20Ｚｒ
0.60Ｙ0.20Ｏ1.90/ 0.05wt％Ｒｈの組成を有するものを
用いた点を除き、実施例１と同様の操作を行い、セリウ
ム系複合酸化物が有する初期、耐久試験後の酸素ストレ
ージ能の評価、および耐久試験の前後における上記セリ
ウム系複合酸化物の酸素ストレージ能の変化率（劣化
率）の評価を行った。このときの結果を表１に示した。
なお、上記セリウム系複合酸化物は、実施例１と同様の
方法によって調製した。ただし、複合酸化物の状態にお
いてセリウム、ジルコニウムおよびイットリウムが所定
の量論比で複合酸化物を形成するように実施例１とは異
なった比率でセリウムイソプロポキシド、ジルコニウム
イソプロポキシド、イットリウムイソプロポキシドを混
合してトルエンに溶解させて混合アルコキシド溶液を作
製し、また、所定量のＲｈ（ロジウム）が担持されるよ
うにＣｅ0.20Ｚｒ0.60Ｙ0.20Ｏ1.90粉末を含むスラリー
に混合する硝酸ロジウム溶液（ロジウム含有量は０．９
８０ｗｔ％）の重量を調整した。Embodiment 8 Ce 0.20 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was carried out in the same manner as in Example 1, except that the one having a composition of 0.60 Y 0.20 O 1.90 / 0.05 wt% Rh was used. Then, the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test was evaluated. Table 1 shows the results.
The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the state of the composite oxide, cerium, zirconium, and yttrium form a composite oxide at a predetermined stoichiometric ratio. The ratio of cerium isopropoxide, zirconium isopropoxide, and yttrium isopropoxide is different from that in Example 1. A mixed alkoxide solution is prepared by mixing and dissolving in a toluene solution, and a rhodium nitrate solution mixed with a slurry containing Ce 0.20 Zr 0.60 Y 0.20 O 1.90 powder so that a predetermined amount of Rh (rhodium) is supported. (Rhodium content is 0.9
(80 wt%).

【００４６】[0046]

【実施例９】セリウム系複合酸化物としてＣｅ0.60Ｚｒ
0.30Ｙ0.10Ｏ1.95/0.1wt％Ｐｄの組成を有するものを用
いた点を除き、実施例１と同様の操作を行い、セリウム
系複合酸化物が有する初期、耐久試験後の酸素ストレー
ジ能の評価、および耐久試験の前後における上記セリウ
ム系複合酸化物の酸素ストレージ能の変化率（劣化率）
の評価を行った。このときの結果を表１に示した。な
お、上記セリウム系複合酸化物は、実施例１と同様の方
法によって調製した。更に、所定量のＰｄ（パラジウ
ム）が担持されるようにＣｅ0.60Ｚｒ0.30Ｙ0.10Ｏ1.95
粉末を含むスラリーに混合する硝酸パラジウム溶液（パ
ラジウム含有量は４．３９９ｗｔ％）の重量を調整し
た。Embodiment 9 Ce 0.60 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was performed in the same manner as in Example 1 except that a compound having a composition of 0.30 Y 0.10 O 1.95 / 0.1 wt% Pd was used. And the rate of change (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test
Was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. Further, Ce 0.60 Zr 0.30 Y 0.10 O 1.95 is applied so that a predetermined amount of Pd (palladium) is supported.
The weight of the palladium nitrate solution (palladium content: 4.399 wt%) to be mixed with the slurry containing the powder was adjusted.

【００４７】[0047]

【実施例１０】セリウム系複合酸化物としてＣｅ0.40Ｚ
ｒ0.45Ｙ0.15Ｏ1.925/0.05wt％Ｐｄの組成を有するもの
を用いた点を除き、実施例１と同様の操作を行い、セリ
ウム系複合酸化物が有する初期、耐久試験後の酸素スト
レージ能の評価、および耐久試験の前後における上記セ
リウム系複合酸化物の酸素ストレージ能の変化率（劣化
率）の評価を行った。このときの結果を表１に示した。
なお、上記セリウム系複合酸化物は、実施例１と同様の
方法によって調製した。ただし、複合酸化物の状態にお
いてセリウム、ジルコニウムおよびイットリウムが所定
の量論比で複合酸化物を形成するように実施例１とは異
なった比率でセリウムイソプロポキシド、ジルコニウム
イソプロポキシド、イットリウムイソプロポキシドを混
合してトルエンに溶解させて混合アルコキシド溶液を作
製し、また、所定量のＰｄ（パラジウム）が担持される
ようにＣｅ0.40Ｚｒ0.45Ｙ0.15Ｏ1.925 粉末を含むスラ
リーに混合するジニトロジアンミンパラジウム硝酸溶液
（パラジウム含有量は８．３３７ｗｔ％）の重量を調整
した。Embodiment 10 Ce 0.40 Z as a cerium-based composite oxide
r 0.45 Y 0.15 O 1.925 /0.05 wt % Pd Except for using a material having a composition of Pd, the same operation as in Example 1 was performed to obtain the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the durability test. The evaluation and the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test were evaluated. Table 1 shows the results.
The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the state of the composite oxide, cerium, zirconium, and yttrium form a composite oxide at a predetermined stoichiometric ratio. The ratio of cerium isopropoxide, zirconium isopropoxide, and yttrium isopropoxide is different from that in Example 1. To prepare a mixed alkoxide solution, and dinitrodiammine palladium mixed with a slurry containing Ce 0.40 Zr 0.45 Y 0.15 O 1.925 powder so that a predetermined amount of Pd (palladium) is supported. The weight of the nitric acid solution (the palladium content was 8.337 wt%) was adjusted.

【００４８】[0048]

【実施例１１】セリウム系複合酸化物としてＣｅ0.20Ｚ
ｒ0.60Ｙ0.20Ｏ1.90/0.2wt％Ｐｄの組成を有するものを
用いた点を除き、実施例１と同様の操作を行い、セリウ
ム系複合酸化物が有する初期、耐久試験後の酸素ストレ
ージ能の評価、および耐久試験の前後における上記セリ
ウム系複合酸化物の酸素ストレージ能の変化率（劣化
率）の評価を行った。このときの結果を表１に示した。
なお、上記セリウム系複合酸化物は、実施例１と同様の
方法によって調製した。ただし、複合酸化物の状態にお
いてセリウム、ジルコニウムおよびイットリウムが所定
の量論比で複合酸化物を形成するように実施例１とは異
なった比率でセリウムイソプロポキシド、ジルコニウム
イソプロポキシド、イットリウムイソプロポキシドを混
合してトルエンに溶解させて混合アルコキシド溶液を作
製し、また、所定量のＰｄ（パラジウム）が担持される
ようにＣｅ0.20Ｚｒ0.60Ｙ0.20Ｏ1.90粉末を含むスラリ
ーに混合するジニトロジアンミンパラジウム硝酸溶液
（パラジウム含有量は８．３３７ｗｔ％）の重量を調整
した。Embodiment 11 Ce 0.20 Z as a cerium-based composite oxide
r 0.60 Y 0.20 O 1.90 /0.2 wt% Pd Except for using a material having a composition of Pd, the same operation as in Example 1 was carried out to obtain the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the durability test. The evaluation and the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test were evaluated. Table 1 shows the results.
The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the composite oxide state, cerium, zirconium and yttrium form a composite oxide at a predetermined stoichiometric ratio, but in a different ratio from that of Example 1, cerium isopropoxide, zirconium isopropoxide, yttrium isopropoxy. And mixed with toluene to form a mixed alkoxide solution, and dinitrodiammine palladium mixed with a slurry containing Ce 0.20 Zr 0.60 Y 0.20 O 1.90 powder so that a predetermined amount of Pd (palladium) is supported. The weight of the nitric acid solution (the palladium content was 8.337 wt%) was adjusted.

【００４９】[0049]

【比較例１】セリウム系複合酸化物としてＣｅ0.60Ｚｒ
0.30Ｙ0.10Ｏ1.95の組成を有するものを用いた点を除
き、実施例１と同様の操作を行い、セリウム系複合酸化
物が有する初期、耐久試験後の酸素ストレージ能の評
価、および耐久試験の前後における上記セリウム系複合
酸化物の酸素ストレージ能の変化率（劣化率）の評価を
行った。このときの結果を表１に示した。なお、上記セ
リウム系複合酸化物は、実施例１と同様の方法によって
調製した。ただし、複合酸化物の状態においてセリウ
ム、ジルコニウムおよびイットリウムが所定の量論比で
複合酸化物を形成するように実施例１とは異なった比率
でセリウムイソプロポキシド、ジルコニウムイソプロポ
キシド、イットリウムイソプロポキシドを混合してトル
エンに溶解させて混合アルコキシド溶液を作製した。Comparative Example 1 Ce 0.60 Zr as a cerium-based composite oxide
The same operation as in Example 1 was performed, except that a material having a composition of 0.30 Y 0.10 O 1.95 was used, and the initial evaluation of the cerium-based composite oxide, the oxygen storage ability after the durability test, and the evaluation of the durability test were performed. The change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. However, in the state of the composite oxide, cerium, zirconium, and yttrium form a composite oxide at a predetermined stoichiometric ratio. The ratio of cerium isopropoxide, zirconium isopropoxide, and yttrium isopropoxide is different from that in Example 1. Were mixed and dissolved in toluene to prepare a mixed alkoxide solution.

【００５０】[0050]

【比較例２】セリウム系酸化物としてＣｅＯ2 の組成を
有するものを用いた点を除き実施例１と同様の操作を行
い、このセリウム系酸化物が有する初期、耐久試験後の
酸素ストレージ能の評価、および耐久試験の前後におけ
る上記セリウム系複合酸化物の酸素ストレージ能の変化
率（劣化率）の評価を行った。このときの結果を表１に
示した。なお、上記セリウム系酸化物は、実施例１と同
様にアルコキシド法をよって調製した。ただし、本比較
例で用いる酸化物には、ジルコニウムおよびイットリウ
ムが含まれていないので、混合アルコキシド溶液ではな
くセリウムアルコキシド溶液を作成し、この溶液を加水
分解した後にＨ2 Ｏ・溶剤を留去・蒸発乾固させて前駆
体を作製し、さらにこの前駆体を焼成することにより調
製した。Comparative Example 2 The same operation as in Example 1 was carried out except that a cerium-based oxide having a composition of CeO 2 was used. The evaluation and the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test were evaluated. Table 1 shows the results. The cerium-based oxide was prepared by the alkoxide method as in Example 1. However, since the oxide used in this comparative example does not contain zirconium and yttrium, a cerium alkoxide solution was prepared instead of a mixed alkoxide solution, and after the solution was hydrolyzed, H 2 O. The precursor was prepared by evaporating to dryness, and then calcined to prepare the precursor.

【００５１】[0051]

【比較例３】セリウム系複合酸化物としてＣｅ0.6 Ｚｒ
0.3 Ｙ0.1 Ｏ1.95/0.1wt％Ｐｔの組成を有するものを用
いた点を除き、実施例１と同様の操作を行い、セリウム
系複合酸化物が有する初期、耐久試験後の酸素ストレー
ジ能の評価、および耐久試験の前後における上記セリウ
ム系複合酸化物の酸素ストレージ能の変化率（劣化率）
の評価を行った。このときの結果を表１に示した。な
お、上記セリウム系複合酸化物は、実施例１と同様の方
法によって調製した。ただし、複合酸化物の状態におい
てセリウム、ジルコニウムおよびイットリウムが所定の
量論比で複合酸化物を形成するように混合アルコキシド
溶液を作製し、また、所定量のプラチナが担持されるよ
うにＣｅ0.6 Ｚｒ0.3 Ｙ0.1 Ｏ1.95粉末を含むスラリー
に混合するジニトロジアンミン白金硝酸溶液（白金含有
量は４．５６９ｗｔ％）の重量を調整した。[Comparative Example 3] Ce 0.6 Zr as cerium complex oxide
The same operation as in Example 1 was performed, except that a material having a composition of 0.3 Y 0.1 O 1.95 / 0.1 wt % Pt was used, and the oxygen storage ability of the cerium-based composite oxide in the initial stage and after the durability test was evaluated. And the rate of change (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test
Was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. However, a mixed alkoxide solution is prepared so that cerium, zirconium and yttrium form a composite oxide at a predetermined stoichiometric ratio in the state of the composite oxide, and Ce 0.6 Zr is prepared so that a predetermined amount of platinum is supported. The weight of a dinitrodiammine platinum nitrate solution (platinum content: 4.569 wt%) to be mixed with the slurry containing 0.3 Y 0.1 O 1.95 powder was adjusted.

【００５２】[0052]

【比較例４】セリウム系複合酸化物としてＣｅ0.40Ｚｒ
0.45Ｙ0.15Ｏ1.925 /0.1wt％Ｐｔの組成を有するものを
用いた点を除き、実施例１と同様の操作を行い、セリウ
ム系複合酸化物が有する初期、耐久試験後の酸素ストレ
ージ能の評価、および耐久試験の前後における上記セリ
ウム系複合酸化物の酸素ストレージ能の変化率（劣化
率）の評価を行った。このときの結果を表１に示した。
なお、上記セリウム系複合酸化物は、実施例１と同様の
方法によって調製した。ただし、複合酸化物の状態にお
いてセリウム、イットリウムおよびジルコニウムが所定
の量論比で複合酸化物を形成するように混合アルコキシ
ド溶液を作製し、また、所定量のプラチナが担持される
ようにＣｅ0.40Ｚｒ0.45Ｙ0.15Ｏ1.925 粉末を含むスラ
リーに混合するジニトロジアンミン白金硝酸溶液（白金
含有量は４．５６９ｗｔ％）の重量を調整した。Comparative Example 4 Ce 0.40 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was performed by performing the same operation as in Example 1 except that a compound having a composition of 0.45 Y 0.15 O 1.925 / 0.1 wt % Pt was used. Then, the change rate (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test was evaluated. Table 1 shows the results.
The cerium-based composite oxide was prepared in the same manner as in Example 1. However, a mixed alkoxide solution is prepared so that cerium, yttrium and zirconium form a composite oxide at a predetermined stoichiometric ratio in the state of the composite oxide, and Ce 0.40 Zr is prepared so that a predetermined amount of platinum is supported. The weight of a dinitrodiammine platinum nitrate solution (platinum content: 4.569 wt%) to be mixed with the slurry containing 0.45 Y 0.15 O 1.925 powder was adjusted.

【００５３】[0053]

【比較例５】セリウム系複合酸化物としてＣｅ0.20Ｚｒ
0.60Ｙ0.20Ｏ1.90/0.1wt％Ｐｔの組成を有するものを用
いた点を除き、実施例１と同様の操作を行い、セリウム
系複合酸化物が有する初期、耐久試験後の酸素ストレー
ジ能の評価、および耐久試験の前後における上記セリウ
ム系複合酸化物の酸素ストレージ能の変化率（劣化率）
の評価を行った。このときの結果を表１に示した。な
お、上記セリウム系複合酸化物は、実施例１と同様の方
法によって調製した。ただし、複合酸化物の状態におい
てセリウム、イットリウムおよびジルコニウムが所定の
量論比で複合酸化物を形成するように混合アルコキシド
溶液を作製し、また、所定量のプラチナが担持されるよ
うにＣｅ0.20Ｚｒ0.60Ｙ0.20Ｏ1.90粉末を含むスラリー
に混合するジニトロジアンミン白金硝酸溶液（白金含有
量は４．５６９ｗｔ％）の重量を調整した。Comparative Example 5 Ce 0.20 Zr as a cerium-based composite oxide
Evaluation of the oxygen storage capacity of the cerium-based composite oxide at the initial stage and after the endurance test was carried out in the same manner as in Example 1, except that the one having a composition of 0.60 Y 0.20 O 1.90 /0.1 wt% Pt was used. And the rate of change (deterioration rate) of the oxygen storage capacity of the cerium-based composite oxide before and after the durability test
Was evaluated. Table 1 shows the results. The cerium-based composite oxide was prepared in the same manner as in Example 1. However, a mixed alkoxide solution is prepared so that cerium, yttrium and zirconium form a composite oxide at a predetermined stoichiometric ratio in the state of the composite oxide, and Ce 0.20 Zr is prepared so that a predetermined amount of platinum is supported. The weight of a dinitrodiammine platinum nitrate solution (platinum content: 4.569 wt%) to be mixed with the slurry containing 0.60 Y 0.20 O 1.90 powder was adjusted.

【００５４】[0054]

【表１】 [Table 1]

【００５５】[0055]

【発明の効果】表１から明らかなように、比較例１およ
び２で用いたセリウム系酸化物に比べて実施例１から１
１で用いたセリウム系複合酸化物の方が格段に変化率が
小さい。すなわち、本願発明のセリウム系複合酸化物、
言い換えれば希土類金属の酸化物を複合しているセリウ
ム系複合酸化物は、高温下において酸化還元が繰り返さ
れた場合であっても良好に酸素ストレージ能を維持して
いることが分かる。As is clear from Table 1, Examples 1 to 1 are different from the cerium-based oxides used in Comparative Examples 1 and 2.
The cerium-based composite oxide used in No. 1 has a much smaller change rate. That is, the cerium-based composite oxide of the present invention,
In other words, it can be seen that the cerium-based composite oxide in which the oxide of the rare earth metal is composited maintains the oxygen storage ability well even when the oxidation-reduction is repeated at a high temperature.

【００５６】特に、実施例１および２の組成を有するセ
リウム系複合酸化物は、初期の酸素ストレージ能、耐久
後の酸素ストレージ能、および耐久性のいずれの点にお
いても優れていることがわかる。In particular, it can be seen that the cerium-based composite oxides having the compositions of Examples 1 and 2 are excellent in any of the initial oxygen storage capacity, the oxygen storage capacity after durability, and the durability.

【００５７】また、比較例３から５と実施例６から１１
とを比較すれば分かるように、セリウム系複合酸化物に
担持させる貴金属をプラチナでなく、ロジウムあるいは
パラジウムとした場合、あるいは遷移元素を含有させた
場合に、高温下において酸化還元が繰り返された場合で
あっても良好に酸素ストレージ能を維持していることが
分かる。Further, Comparative Examples 3 to 5 and Examples 6 to 11
As can be seen from the comparison, when the noble metal supported on the cerium-based composite oxide is not platinum but rhodium or palladium, or when a transition element is contained, when redox is repeated at high temperature However, it can be seen that the oxygen storage ability is maintained well.

【００５８】したがって、本願発明のセリウム系複合酸
化物は、１０００℃の高温下で酸化還元が繰り返された
場合であっても、酸素ストレージ能を良好に維持するこ
とができるので、高温状態で気相雰囲気のガス組成が変
動する自動車の排気ガスを浄化する触媒の効率化のため
に好適に使用することができる。Therefore, the cerium-based composite oxide of the present invention can maintain a good oxygen storage capacity even when redox is repeated at a high temperature of 1000 ° C. The present invention can be suitably used for improving the efficiency of a catalyst for purifying exhaust gas of an automobile in which the gas composition of the phase atmosphere fluctuates.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 山本 真里 滋賀県蒲生郡竜王町大字山之上3000番地 ダイハツ工業株式会社滋賀テクニカルセン ター内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mari Yamamoto 3000 Oyamanogami, Ryuo-cho, Gamo-gun, Shiga Prefecture

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 一般式 【化１】 で表され、 Ｒは希土類金属を、ｚは酸素欠陥量を示し、０．２≦ｘ
＋ｙ≦０．９、０．１≦ｘ≦０．８、０．０５≦ｙ≦
０．３である、酸素吸蔵性セリウム系複合酸化物。1. A compound of the general formula R represents a rare earth metal, z represents the amount of oxygen defects, and 0.2 ≦ x
+ Y ≦ 0.9, 0.1 ≦ x ≦ 0.8, 0.05 ≦ y ≦
0.3, an oxygen-storing cerium-based composite oxide. 【請求項２】 上記一般式において、０．４≦ｘ＋ｙ≦
０．８、０．３５≦ｘ≦０．７、０．０５≦ｙ≦０．２
である、請求項１に記載の酸素吸蔵性セリウム系複合酸
化物。2. In the above general formula, 0.4 ≦ x + y ≦
0.8, 0.35 ≦ x ≦ 0.7, 0.05 ≦ y ≦ 0.2
The oxygen-storing cerium-based composite oxide according to claim 1, which is: 【請求項３】 少なくとも一部が固溶体である、請求項
１または２に記載の酸素吸蔵性セリウム系複合酸化物。3. The oxygen-storing cerium-based composite oxide according to claim 1, wherein at least a part thereof is a solid solution. 【請求項４】 さらに、貴金属が担持されている、請求
項１から３のいずれかに記載の酸素吸蔵性セリウム系複
合酸化物。4. The oxygen-storing cerium-based composite oxide according to claim 1, further comprising a noble metal. 【請求項５】 上記貴金属は、ＰｄまたはＲｈである、
請求項４に記載の酸素吸蔵性セリウム系複合酸化物。5. The method according to claim 1, wherein the noble metal is Pd or Rh.
The oxygen-storing cerium-based composite oxide according to claim 4. 【請求項６】 遷移元素が担持されている、請求項１か
ら３のいずれかに記載の酸素吸蔵性セリウム系複合酸化
物。6. The oxygen-storing cerium-based composite oxide according to claim 1, wherein a transition element is supported. 【請求項７】 上記遷移金属は、Ｆｅ、Ｃｏ、Ｎｉ、Ｃ
ｕからなる群のうちの少なくとも１つである、請求項６
に記載の酸素吸蔵性セリウム系複合酸化物。7. The transition metal is Fe, Co, Ni, C
7. At least one of the group consisting of u.
2. The oxygen-storing cerium-based composite oxide according to item 1. 【請求項８】 上記遷移金属は、Ｆｅである、請求項７
に記載の酸素吸蔵性セリウム系複合酸化物。8. The method according to claim 7, wherein the transition metal is Fe.
2. The oxygen-storing cerium-based composite oxide according to item 1.
JP02685197A 1997-02-10 1997-02-10 Oxygen storage cerium-based composite oxide Expired - Fee Related JP3429967B2 (en)

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DE19805259A DE19805259B4 (en) 1997-02-10 1998-02-10 Oxygen-storing cerium complex oxide

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