【０００１】[0001]
【産業上の利用分野】本発明は、排ガス、特に自動車の
排ガスの浄化触媒に助触媒として用いられる水酸化セリ
ウム及び酸化セリウムに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cerium hydroxide and cerium oxide used as a cocatalyst for purifying exhaust gas, particularly automobile exhaust gas.
【０００２】[0002]
【従来の技術】排ガス中のＣＯ、ＨＣ、Ｎｏｘの３成分
を同時に浄化するために、Ｐｔ、Ｐｄ、Ｒｄなどの触媒
金属が用いられている。これら触媒の性能を助長するた
めに従来はＮｉが添加されていたが、最近ではＮｉより
もＣｅＯ2がよい性能が得られると「触媒」１９８９年
第３１巻５６６〜５７１ページに報告されている。触媒
上のＣｅＯ2は酸素貯蔵効果、水性ガスシフト反応促進
効果、貴金属の分散性向上効果、担体の高温耐熱性向上
効果を有するとされている。2. Description of the Related Art Catalytic metals such as Pt, Pd and Rd are used to purify three components of CO, HC and Nox in exhaust gas at the same time. Although Ni was conventionally added to promote the performance of these catalysts, it has recently been reported in "Catalyst" 1989, Vol. 31, pp. 566-571 that CeO2 has better performance than Ni. . CeO2 on the catalyst is said to have an oxygen storage effect, a water gas shift reaction promoting effect, a noble metal dispersibility improving effect, and a high temperature heat resistance improving effect of the carrier.
【０００３】この報告によれば、触媒上のＣｅＯ2の結
晶化は温度の上昇にほぼ比例して進行し、Ｏ2吸着量は
８００℃を超えると急激に低下する。このＣｅＯ2の結
晶子径の成長を押えるためにＢａとＺｒを添加した高温
耐熱用触媒も既に市販されている。浄化性能に大きな関
係を持つのはＯ2吸着量である。Ｏ2吸着量はＣｅＯ2の
結晶子径が小さいほど大きくなる。従って、焼成された
担体のアルミナ中におけるＣｅＯ2の結晶子径が小さい
と、その担体に白金族金属を担持させた触媒は、触媒と
しての性能の向上したものとなる。According to this report, the crystallization of CeO2 on the catalyst proceeds almost in proportion to the temperature rise, and the O2 adsorption amount drops sharply when the temperature exceeds 800 ° C. A high temperature heat resistant catalyst to which Ba and Zr are added in order to suppress the growth of the crystallite diameter of CeO2 is already on the market. The amount of O2 adsorption has a great relationship with the purification performance. The smaller the crystallite diameter of CeO2 , the larger the amount of O2 adsorbed. Therefore, if the crystallite size of CeO2 in alumina of the calcined support is small, the catalyst in which the platinum group metal is supported on the support has improved performance as a catalyst.
【０００４】触媒担体への酸化セリウムの担持は、セリ
ウム塩の水溶液や、水酸化セリウムをアルミナ等の触媒
担体に付着させ、乾燥焼成するか、あるいはセリウム塩
の水溶液と担体とを混合し、この混合物にアルカリを添
加して、担体上に水酸化セリウムを析出せしめ、これを
乾燥焼成する方法、更にアルミナ粉末と酸化セリウム粉
末とのスラリーを多孔質担体に付着せしめる方法などに
より行われている。セリウム塩の水溶液にアルカリを添
加し水酸化セリウムとする場合には、特開昭５６−１４
７６３４号公報、特開昭５７−５６０４１号公報、特開
昭５７−１１９８３５号公報に示されているように、一
般に三価の水溶性セリウム塩を用い、アルカリでｐＨ８
〜１１にして水酸化セリウムを生成せしめている。To support cerium oxide on a catalyst carrier, an aqueous solution of cerium salt or cerium hydroxide is adhered to a catalyst carrier such as alumina and dried or calcined, or an aqueous solution of cerium salt and a carrier are mixed, This is carried out by a method of adding an alkali to the mixture to precipitate cerium hydroxide on the carrier, drying and firing the cerium hydroxide, and a method of attaching a slurry of alumina powder and cerium oxide powder to the porous carrier. When an alkali is added to an aqueous solution of cerium salt to form cerium hydroxide, it is disclosed in JP-A-56-14.
As disclosed in Japanese Patent No. 7634, Japanese Patent Application Laid-Open No. 57-56041, and Japanese Patent Application Laid-Open No. 57-119835, a trivalent water-soluble cerium salt is generally used, and the pH is adjusted to 8 at an alkali.
The cerium hydroxide is made to be -11.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、このような
用途に用いて最終的に得られた酸化セリウムの結晶子径
が小さく、従来よりも酸素吸蔵能の大きく、担体へ分散
性よく担持できる触媒を得ることのできる水酸化セリウ
ムおよび酸化セリウムの製造方法を提供することを課題
とする。DISCLOSURE OF THE INVENTION According to the present invention, the cerium oxide finally obtained for such use has a smaller crystallite size, a larger oxygen storage capacity than before, and a good dispersibility on a carrier. An object of the present invention is to provide a method for producing cerium hydroxide and cerium oxide that can obtain a catalyst that can be obtained.
【０００６】[0006]
【課題を解決するための手段】本発明は上記の課題を解
決するため、硫酸第二セリウム水溶液にアルカリ水溶液
を加えて加水分解により水酸化セリウムを沈澱させる
際、硫酸第二セリウム水溶液にアルカリ水溶液を滴下し
一旦生成した水酸化セリウムが硫酸第二セリウム水溶液
に再溶解するまでアルカリ水溶液の滴下を一時中止し、
完全に再溶解させた後再びアルカリ水溶液の添加をする
操作を行い、生成した水酸化セリウムが再溶解しない状
態の反応液のｐＨが２.０以下で水酸化セリウムを析出
せしめる反応を終了して水酸化セリウムを得ること、及
びこれを洗浄、乾燥、焼成して酸化セリウムとすること
にある。[Means for Solving the Problems] In order to solve the above problems, the present invention is directed to the addition of an alkaline aqueous solution to a ceric sulfate aqueous solution to precipitate cerium hydroxide by hydrolysis. , And once the cerium hydroxide that was once generated was redissolved in the cerium sulfate aqueous solution, the addition of the alkaline aqueous solution was temporarily stopped,
After completely re-dissolving, the operation of adding an alkaline aqueous solution again is performed, and the reaction for precipitating cerium hydroxide is completed when the pH of the reaction solution in which the produced cerium hydroxide is not re-dissolved is 2.0 or less. The purpose is to obtain cerium hydroxide and to wash, dry, and calcine it to obtain cerium oxide.
【０００７】本発明に用いる硫酸第二セリウムとして
は、一般にＣｅ（ＳＯ4）2・４Ｈ2Ｏが用いられる。ア
ルカリとしては、一般にアルカリとして使用されている
水酸化ナトリウム、水酸化カリウム、水酸化カルシウ
ム、水酸化マグネシウム、アンモニア水を用いることが
できる。Ce (SO4 )2 .4H2 O is generally used as the ceric sulfate used in the present invention. As the alkali, it is possible to use sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, or aqueous ammonia which is generally used as an alkali.
【０００８】セリウム塩の水溶液としては１０〜５００
ｍｍｏｌ／ｌ、一般的には５０〜２００ｍｍｏｌ／ｌ程
度の濃度が用いられ、これより薄いと生産性が悪くな
り、これより濃いときは、反応の際のｐＨの調節が困難
となる。アルカリ水溶液としては１０〜２０００ｍｍｏ
ｌ／ｌ、セリウム塩水溶液濃度の１〜１０００倍程度、
通常１〜１０倍程度である。An aqueous solution of cerium salt is 10 to 500
A concentration of about mmol / l, generally about 50 to 200 mmol / l, is used. If the concentration is lower than this, the productivity deteriorates. If the concentration is higher than this, it becomes difficult to control the pH during the reaction. 10 ~ 2000mmo as alkaline aqueous solution
l / l, about 1 to 1000 times the cerium salt aqueous solution concentration,
It is usually about 1 to 10 times.
【０００９】[0009]
【作用】本発明製造方法においては、用意したセリウム
塩水溶液にアルカリ水溶液を滴下して、液温２０〜８０
℃、通常２０〜４０℃で、液を激しく撹拌しながら加水
分解反応を行わせるのであるが、この時、セリウム塩水
溶液にアルカリ水溶液を滴下すると、反応液中に微細な
水酸化セリウムの結晶が生成する。結晶の生成した反応
液に続けてアルカリを添加すると、生成した水酸化セリ
ウムが反応液中で均一に分散しないので、生成する水酸
化セリウムの粒度が不均一となり水酸化セリウムの結晶
粒が大きくなり、結局得られた水酸化セリウムを焼成し
て得た酸性セリウムも結晶子径の小さいものが得られな
くなる。これを避けるためにアルカリ水溶液を滴下し一
旦生成した水酸化セリウムが硫酸第二セリウム水溶液に
再溶解するまでアルカリ水溶液の滴下を一時中止し、完
全に再溶解した後アルカリ水溶液を添加する操作を行う
ものである。In the production method of the present invention, an aqueous alkali solution is added dropwise to the prepared aqueous cerium salt solution to obtain a liquid temperature of 20-80.
The hydrolysis reaction is carried out at ℃, usually 20 to 40 ℃ while vigorously stirring the solution. At this time, when an alkaline aqueous solution is dropped into the cerium salt aqueous solution, fine cerium hydroxide crystals are formed in the reaction solution. To generate. If alkali is added continuously to the reaction solution in which crystals are generated, the generated cerium hydroxide will not be uniformly dispersed in the reaction solution, and the particle size of the generated cerium hydroxide will be uneven and the crystal particles of cerium hydroxide will increase. As a result, it becomes impossible to obtain an acidic cerium having a small crystallite size by calcining the obtained cerium hydroxide. In order to avoid this, the operation of adding the alkaline aqueous solution by temporarily dropping the alkaline aqueous solution until the cerium hydroxide once generated is redissolved in the aqueous cerium sulfate aqueous solution and completely re-dissolved It is a thing.
【００１０】この加水分解反応は、反応液のｐＨをｐＨ
計で監視しながら行う。例えば、硫酸第二セリウム水溶
液のｐＨは反応開始時には１.０で、アルカリ水溶液を
添加して行くとｐＨは上昇するが、加えたアルカリ量に
対してその上昇の仕方は一定せず、初めのうちは遅く、
一旦水酸化セリウム結晶が反応液中で安定に存在する中
和点に達すると、ｐＨが急上昇するようになる。このた
めアルカリの添加を徐々に行わないと、反応液のｐＨを
ｐＨ計で監視しながら行っても、ｐＨを急上昇させてし
まう。アルカリの添加速度はセリウム塩水溶液中のセリ
ウム塩１ｍｍｏｌに対して毎分０.１ｍｍｏｌ以下、好
ましくは０.０１ ｍｍｏｌ前後とするのがよい。In this hydrolysis reaction, the pH of the reaction solution is adjusted to pH.
Perform while monitoring with a meter. For example, the pH of the cerium sulfate aqueous solution is 1.0 at the start of the reaction, and the pH increases with the addition of the alkaline aqueous solution, but the manner of the increase is not constant with respect to the amount of the added alkali. We are late,
Once the neutralization point where the cerium hydroxide crystals are stably present in the reaction solution is reached, the pH suddenly rises. For this reason, if the alkali is not added gradually, the pH of the reaction solution will rise sharply even if it is monitored with a pH meter. The addition rate of alkali is 0.1 mmol / min or less, preferably about 0.01 mmol / min with respect to 1 mmol of cerium salt in the cerium salt aqueous solution.
【００１１】硫酸セリウム水溶液を加水分解して水酸化
セリウムが安定に存在するようになるｐＨは１.４であ
るが、このように出来るだけ低いｐＨで水酸化セリウム
を安定に存在せしめ、そこで反応を中止することによ
り、これから得られる酸化セリウムの結晶子径を最も小
さくできるようにしたものである。三価のセリウム塩を
使用する従来法と異なり、このように低いｐＨ領域で水
酸化セリウムを生成できる理由は、明らかではないが、
四価のセリウム塩を出発物質として使用することによる
ものと考えられる。The pH at which cerium hydroxide aqueous solution is hydrolyzed and cerium hydroxide is stably present is 1.4. However, cerium hydroxide is allowed to stably exist at such a low pH as possible and the reaction is carried out there. By stopping the above, the crystallite diameter of cerium oxide obtained from this can be minimized. It is not clear why, unlike the conventional method using a trivalent cerium salt, cerium hydroxide can be produced in such a low pH range,
It is believed that this is due to the use of a tetravalent cerium salt as a starting material.
【００１２】本発明で、加水分解時のｐＨの最高値を
２.０とするのは、ｐＨが２.０を超えて反応を終了する
と、最終的に得られた酸化セリウムの結晶子径が大きく
なり、酸素吸蔵能が低下するからである。その理由は、
ｐＨが２.０を超えると、生成する水酸化セリウムに配
位する水和イオンの数が増加することによると考えられ
る。In the present invention, the maximum value of pH during hydrolysis is set to 2.0, that is, when the reaction is completed when the pH exceeds 2.0, the crystallite size of the cerium oxide finally obtained is This is because the oxygen storage capacity becomes large and the oxygen storage capacity decreases. The reason is,
It is considered that when the pH exceeds 2.0, the number of hydrated ions coordinated with the generated cerium hydroxide increases.
【００１３】得られた水酸化セリウムの沈澱は、遠心濾
過あるいは吸引濾過などの方法により反応母液と分離さ
れる。この操作は、反応物を周囲温度の１０〜２５℃に
冷却する前又は後でもよい。母液と分離した水酸化セリ
ウムは５〜９０℃の蒸留水やイオン交換水で数回洗浄し
て水酸化セリウムに付着している酸性陰イオンを除去
し、大気中あるいは１０-2〜１００ｍｍＨｇ程度の減圧
下で乾燥し、９０〜２００℃の温度で１０〜４８時間乾
燥し、更に３００〜５００℃で２〜１２時間焼成して酸
化セリウムとされる。The obtained cerium hydroxide precipitate is separated from the reaction mother liquor by a method such as centrifugal filtration or suction filtration. This operation may be before or after cooling the reaction to ambient temperature of 10-25 ° C. The cerium hydroxide separated from the mother liquor is washed several times with distilled water or ion-exchanged water at 5 to 90 ° C to remove the acidic anions adhering to the cerium hydroxide, and the cerium hydroxide is removed from the atmosphere or at a temperature of 10-2 to 100 mmHg. It is dried under reduced pressure, dried at a temperature of 90 to 200 ° C. for 10 to 48 hours, and further baked at 300 to 500 ° C. for 2 to 12 hours to obtain cerium oxide.
【００１４】本発明において、酸化セリウムの結晶子径
Ｌは、Ｘ線回折図における（３３１）面の線幅からシェ
ラーの式を用いて以下のように計算して求めたものであ
る。 Ｌ＝Ｋλ／β・ｃｏｓθ 但し Ｋ＝０.９ ：Sherrer 定数 λ（Å） ：Ｋα１線の波長 １.５４Å β（rad） ：ピークの線幅（半値幅） θ ：入射角In the present invention, the crystallite diameter L of cerium oxide is obtained by the following calculation from the line width of the (331) plane in the X-ray diffraction diagram using Scherrer's equation. L = Kλ / β · cos θ where K = 0.9: Sherrer constant λ (Å): Wavelength of Kα1 line 1.54Å β (rad): Peak line width (half width) θ: Incident angle
【００１５】また、酸化セリウムの酸素吸蔵能の評価
は、Journal of Catalysis., vol.86,ｐ.254(1984)に記
載されている方法に習って酸化セリウム０.０５ｇに対
して以下のように行った。 1)ヘリウム気流（１００ｍｌ／ｍｉｎ）中５００℃で３
０分の前処理をする。 2)ヘリウム気流４００℃及び５００℃に設定。 3)次に１％Ｏ2／Ｈｅの気流を１０秒間（２.５ｍｌ）流
し、次の４分５０秒間Ｈｅを流すサイクルを、導入した
Ｏ2が消費されなくなるまで（酸化セリウムがそれ以上
Ｏ2を吸収しなくなるまで）繰り返す。Further, the evaluation of the oxygen storage capacity of cerium oxide was carried out according to the method described in Journal of Catalysis., Vol.86, p.254 (1984) with respect to 0.05 g of cerium oxide as follows. Went to. 1) 3 at 500 ° C in helium gas flow (100 ml / min)
Pre-process for 0 minutes. 2) Helium flow set to 400 ℃ and 500 ℃. 3) Next, a cycle of flowing a 1% O2 / He gas stream for 10 seconds (2.5 ml) and then flowing He for 4 minutes and 50 seconds is continued until the introduced O2 is no longer consumed (cerium oxide is no more than O Repeat until2 no longer absorbs).
【００１６】4)１％ＣＯ／Ｈｅの気流を１０秒間（５.
０ｍｌ）流し、次の４分５０秒間Ｈｅを流す操作を繰り
返し、ＣＯが消費されなくなった（酸化セリウムがそれ
以上ＣＯを吸収しなくなった）時点で止める。 5)次に、１％Ｏ2／Ｈｅの気流を１０秒間（２.５ｍｌ）
流し、次の４分５０秒間Ｈｅを流す操作を繰り返し、Ｏ
2が消費されなくなった時点で止め、この時の全Ｏ2消費
量（積算値モル）を酸化セリウムのモル量で割ってＯＳ
ＣＣ（OxygenStorage Capacity Cumulative)を計算す
る。4) An air flow of 1% CO / He was applied for 10 seconds (5.
0 ml) and then He is flown for the next 4 minutes and 50 seconds, and is stopped when CO is no longer consumed (cerium oxide no longer absorbs CO). 5) Next, air flow of 1% O2 / He for 10 seconds (2.5 ml)
Repeat the operation of flowing He and flowing He for the next 4 minutes and 50 seconds.
Stop when2 is no longer consumed, and divide the total O2 consumption (integrated value mol) at this time by the molar amount of cerium oxide to give the OS.
Calculate CC (Oxygen Storage Capacity Cumulative).
【００１７】[0017]
実施例１ １００ｍｍｏｌ／ｌ濃度のＣｅ（ＳＯ4）2水溶液１ｌを
２５℃に保ち、この液を激しく撹拌しながら、ビュレッ
トから１ｍｏｌ／ｌ濃度の水酸化ナトリウム水溶液を
１.０ｍｌ／ｍｉｎの滴下速度で滴下した。水酸化ナト
リウム水溶液を約４０ｍｌ滴下した時点で白色微結晶の
水酸化セリウムの生成が認められた。この時点で水酸化
ナトリウム水溶液の滴下を一時中止し、撹拌を続けたと
ころやがて結晶は完全に溶解して消失した。再び水酸化
ナトリウム水溶液の滴下を開始し、水酸化ナトリウム水
溶液１８０ｍｌを滴下した時点で生成した白色微結晶は
溶解しなくなった。この時のｐＨは１.４であったが、
更に水酸化ナトリウム水溶液の滴下を続け水酸化ナトリ
ウム水溶液２００ｍｌを添加した時点で反応を終了し
た。このときのｐＨは１.５であった。Example 1 1 l of an aqueous solution of Ce (SO4 )2 having a concentration of 100 mmol / l was kept at 25 ° C., and the solution was vigorously stirred, and a 1 mol / l aqueous solution of sodium hydroxide was dripped from a buret at a rate of 1.0 ml / min. It was dripped at. When about 40 ml of the aqueous sodium hydroxide solution was added dropwise, formation of white microcrystalline cerium hydroxide was observed. At this point, the dropping of the aqueous sodium hydroxide solution was temporarily stopped, and when stirring was continued, the crystals completely dissolved and disappeared. The dropping of the aqueous sodium hydroxide solution was started again, and the white microcrystals formed when 180 ml of the aqueous sodium hydroxide solution was dropped were not dissolved. The pH at this time was 1.4,
The reaction was terminated at the point of time when 200 ml of the sodium hydroxide aqueous solution was added by continuing the dropwise addition of the sodium hydroxide aqueous solution. The pH at this time was 1.5.
【００１８】得られた黄色の沈澱物を濾別し、これを８
０℃のイオン交換水１００ｍｌ中に分散させて５分間撹
拌分散し濾過する操作を３回繰り返した後、１２０℃で
１２時間乾燥し、更に空気中で９００℃で３時間焼成し
て酸化セリウム粉末を得た。この酸化セリウム粉末の結
晶子径は、上記のＸ線回折図の結果からの計算で４００
Åであった。前記の酸化セリウムの酸素吸蔵能の評価法
に従って試験を行った結果、ＯＳＣＣは４００℃で１.
３ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ2、５００℃で５.７
ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ2であった。The yellow precipitate obtained was filtered off and washed with 8
Cerium oxide powder was dispersed in 100 ml of 0 ° C. ion-exchanged water, stirred and dispersed for 5 minutes and filtered three times, dried at 120 ° C. for 12 hours, and further calcined in air at 900 ° C. for 3 hours. Got The crystallite diameter of this cerium oxide powder is 400 calculated from the above X-ray diffraction pattern.
It was Å. As a result of a test conducted according to the above-mentioned evaluation method of oxygen storage capacity of cerium oxide, OSCC was 1.
3mmol-O 2 / mol-CeO 2, 5.7 at 500 ° C.
It wasmmol-O 2 / mol-CeO 2.
【００１９】実施例２ 実施例１において、反応終了時点でのｐＨを１.９とし
た以外は実施例１と同様にして酸化セリウム粉末を得
た。この酸化セリウム粉末の結晶子径を実施例１と同様
に計算して求めた結果４１０Åであった。また、前記の
酸化セリウムの酸素吸蔵能の評価法に従って試験を行っ
た結果、ＯＳＣＣは４００℃で１.４ｍｍｏｌ−Ｏ2／ｍ
ｏｌ−ＣｅＯ2、５００℃で５.２ｍｍｏｌ−Ｏ2／ｍｏ
ｌ−ＣｅＯ2であった。Example 2 A cerium oxide powder was obtained in the same manner as in Example 1 except that the pH at the end of the reaction was 1.9. The crystallite size of this cerium oxide powder was calculated in the same manner as in Example 1 and the result was 410Å. In addition, as a result of performing a test according to the evaluation method of the oxygen storage capacity of cerium oxide, OSCC was 1.4 mmol-O2 / m at 400 ° C.
ol-CeO2 , 5.2 mmol-O2 / mo at 500 ° C.
It was 1-CeO2 .
【００２０】比較例１ 実施例１において、反応終了時点でのｐＨを２.１とし
た以外は実施例１と同様にして酸化セリウム粉末を得
た。この酸化セリウム粉末の結晶子径を実施例１と同様
に計算して求めた結果４７０Åであった。また、前記の
酸化セリウムの酸素吸蔵能の評価法に従って試験を行っ
た結果、ＯＳＣＣは４００℃で１.１ｍｍｏｌ−Ｏ2／ｍ
ｏｌ−ＣｅＯ2、５００℃で３.９ｍｍｏｌ−Ｏ2／ｍｏ
ｌ−ＣｅＯ2であった。Comparative Example 1 A cerium oxide powder was obtained in the same manner as in Example 1 except that the pH at the end of the reaction was 2.1. The crystallite size of this cerium oxide powder was calculated in the same manner as in Example 1 and found to be 470Å. In addition, as a result of performing a test according to the evaluation method of the oxygen storage capacity of cerium oxide, the OSCC was 1.1 mmol-O2 / m at 400 ° C.
ol-CeO2 , 3.9 mmol-O2 / mo at 500 ° C.
It was 1-CeO2 .
【００２１】比較例２ 実施例１において、セリウム塩としてＣｅ（ＳＯ4）2・
４Ｈ2Ｏを用い、最終ｐＨを８.１とした以外は実施例１
と同様にして酸化セリウム粉末を得た。この酸化セリウ
ム粉末の結晶子径を実施例１と同様に計算して求めた結
果５３０Åであった。また、前記の酸化セリウムのＣＯ
酸素吸蔵能の評価法に従って試験を行った結果、ＯＳＣ
Ｃは４００℃で１.０ｍｍｏｌ−Ｏ2／ｍｏｌ−Ｃｅ
Ｏ2、５００℃で２.４ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ2
であった。Comparative Example 2 In Example 1, as the cerium salt, Ce (SO4 )2
Example 1 except that 4H2 O was used and the final pH was 8.1.
Cerium oxide powder was obtained in the same manner as in. The crystallite size of this cerium oxide powder was calculated in the same manner as in Example 1 and the result was 530Å. In addition, CO of cerium oxide described above
As a result of performing a test according to the evaluation method of oxygen storage capacity, OSC
C is 1.0 mmol-O2 / mol-Ce at 400 ° C.
O2 , 2.4 mmol-O2 / mol-CeO2 at 500 ° C.
Met.
【００２２】比較例３ 実施例１において、セリウム塩として三価のＣｅ2（Ｓ
Ｏ4）3・８Ｈ2Ｏを用いた以外は実施例１と同様にして
酸化セリウム粉末を得た。この酸化セリウム粉末の結晶
子径を実施例１と同様に計算して求めた結果５００Åで
あった。また、前記の酸化セリウムの酸素吸蔵能の評価
法に従って試験を行った結果、ＯＳＣＣは４００℃で
１．０ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ2、５００℃で
２.７ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ2であった。Comparative Example 3 In Example 1, trivalent Ce2 (S) was used as the cerium salt.
O4) except for using3 · 8H2 O was obtained cerium oxide powder in the same manner as in Example 1. The crystallite size of this cerium oxide powder was calculated in the same manner as in Example 1 and was found to be 500Å. Further, as a result of the test according to the evaluation method of the oxygen storage capacity of the cerium oxide, OSCC is 2.7mmol-O2 / mol-CeO in1.0mmol-O 2 / mol-CeO 2, 500 ℃ at 400 ° C.Was 2 .
【００２３】比較例４ 硫酸第二セリウム４水和物を３００℃で加熱分解し、更
に９００℃で３時間焼成して酸化セリウムを得た。この
酸化セリウム粉末の結晶子径は、上記のＸ線回折図の結
果からの計算で７００Åであった。前記の酸化セリウム
の酸素吸蔵能の評価法に従って試験を行った結果、ＯＳ
ＣＣは４００℃で０.４ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ
2、５００℃で１.６ｍｍｏｌ−Ｏ2／ｍｏｌ−ＣｅＯ2で
あった。Comparative Example 4 Cerium sulfate tetrahydrate was decomposed by heating at 300 ° C. and further calcined at 900 ° C. for 3 hours to obtain cerium oxide. The crystallite size of this cerium oxide powder was 700Å as calculated from the results of the above X-ray diffraction pattern. As a result of performing a test according to the above-mentioned evaluation method of oxygen storage capacity of cerium oxide,
CC is 0.4mmol-O2 / mol-CeO at 400 ℃
2 was 1.6 mmol-O2 / mol-CeO2 at 500 ° C.
【００２４】[0024]
【発明の効果】本発明によれば、最終的に得られた酸化
セリウムの結晶子径が小さく、従来よりも酸素吸蔵能の
大きく、担体へ分散性よく担持できる触媒を得ることの
できる水酸化セリウムおよび酸化セリウムの製造方法を
提供することができる。INDUSTRIAL APPLICABILITY According to the present invention, hydroxylation can be obtained in which the finally obtained cerium oxide has a smaller crystallite size, a larger oxygen storage capacity than before, and can be supported on the carrier with good dispersibility. A method for producing cerium and cerium oxide can be provided.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4037261AJPH05208816A (en) | 1992-01-28 | 1992-01-28 | Method for producing cerium hydroxide and cerium oxide |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4037261AJPH05208816A (en) | 1992-01-28 | 1992-01-28 | Method for producing cerium hydroxide and cerium oxide |
| Publication Number | Publication Date |
|---|---|
| JPH05208816Atrue JPH05208816A (en) | 1993-08-20 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4037261APendingJPH05208816A (en) | 1992-01-28 | 1992-01-28 | Method for producing cerium hydroxide and cerium oxide |
| Country | Link |
|---|---|
| JP (1) | JPH05208816A (en) |
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| US8568792B2 (en) | 1997-09-19 | 2013-10-29 | Cytochroma Development Inc. | Metal compounds, mixed or sulphated, as phosphate binders |
| JPH11228135A (en)* | 1998-02-17 | 1999-08-24 | Toray Ind Inc | Cerium oxide powder and cosmetic material, coating material and plastic containing the same |
| KR100453552B1 (en)* | 2001-12-26 | 2004-10-20 | 한국지질자원연구원 | A method for manufacturing of cerium hydroxide removal of fluoride from the bastnasite |
| US7473408B2 (en) | 2002-04-15 | 2009-01-06 | Lg Chem, Ltd. | Method for preparing single crystalline cerium oxide powders |
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| US10201501B2 (en) | 2007-07-27 | 2019-02-12 | Opko Ireland Global Holdings, Ltd. | Mixed metal compounds used as antacids |
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