JP2002220229A - Method for producing ammonium cerium (iv) nitrate - Google Patents
Method for producing ammonium cerium (iv) nitrateInfo
- Publication number
- JP2002220229A JP2002220229A JP2001010025A JP2001010025A JP2002220229A JP 2002220229 A JP2002220229 A JP 2002220229A JP 2001010025 A JP2001010025 A JP 2001010025A JP 2001010025 A JP2001010025 A JP 2001010025A JP 2002220229 A JP2002220229 A JP 2002220229A
- Authority
- JP
- Japan
- Prior art keywords
- cerium
- ammonium nitrate
- aqueous solution
- temperature
- nitric acid
- 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.)
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Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、硝酸セリウム(IV)
アンモニウムの製造方法に関する。The present invention relates to cerium (IV) nitrate
The present invention relates to a method for producing ammonium.
【０００２】[0002]
【従来の技術】硝酸セリウム(IV)アンモニウムは、式
（Ｉ） で示される化合物であって、酸化剤として有用な化合物
である。2. Description of the Related Art Cerium (IV) ammonium nitrate has the formula (I) Which is a compound useful as an oxidizing agent.
【０００３】かかる硝酸セリウム(IV)アンモニウムの製
造方法としては、酸化セリウム(IV)水和物〔Ce(IV)O2・2
H2O〕または水酸化セリウム(IV)〔Ce(IV)(OH)4〕を硝酸
水溶液に溶解させた後、硝酸アンモニウム〔NH4NO3〕と
混合する方法が知られており、混合後の混合物をそのま
ま冷却することで、硝酸セリウム(IV)アンモニウムの結
晶を得ることができる（特開平３−１５３５２０号公
報）。As a method for producing such cerium (IV) ammonium nitrate, cerium (IV) oxide hydrate [Ce (IV) O 2 .2
H 2 O] or after cerium (IV) hydroxide [Ce (IV) and (OH) 4] was dissolved in aqueous nitric acid solution, is known a method of mixing the ammonium nitrate [NH 4 NO 3], after mixing By cooling the mixture as it is, crystals of cerium (IV) ammonium nitrate can be obtained (JP-A-3-153520).
【０００４】しかし、かかる従来の製造方法で得られる
硝酸セリウム(IV)アンモニウムは、粒子径の小さい結晶
を多く含むものであった。硝酸セリウム(IV)アンモニウ
ムの結晶に含まれる粒子径の小さい結晶の割合が多くな
ると、含水率が高くなり易くなるなど、その取り扱いが
不便となる。However, cerium (IV) ammonium nitrate obtained by such a conventional production method contains many crystals having a small particle size. When the proportion of crystals having a small particle diameter contained in the crystals of cerium (IV) ammonium nitrate increases, the handling becomes inconvenient, for example, the water content tends to increase.
【０００５】[0005]
【発明が解決しようとする課題】そこで、本発明者は、
粒子径の小さい結晶の割合が少ない硝酸セリウム(IV)ア
ンモニウムの製造方法を開発するべく鋭意検討した結
果、硝酸セリウム(IV)アンモニウムの水溶液に種晶を加
える際の温度を該水溶液の飽和温度（Ｔ1）よりも１０
℃低い温度（Ｔ1−１０℃）またはこれ以上の温度と
し、該水溶液を所定の速度以下の冷却速度で冷却するこ
とによって得られる硝酸セリウム(IV)アンモニウムの結
晶は、粒子径の小さいものの割合が少ないことを見出
し、本発明に至った。Therefore, the present inventor has proposed:
As a result of intensive studies to develop a method for producing cerium (IV) ammonium nitrate having a small proportion of crystals having a small particle diameter, the temperature at which a seed crystal was added to an aqueous solution of cerium (IV) ammonium nitrate was set to the saturation temperature of the aqueous solution ( 10 than T 1 )
Cerium (IV) ammonium nitrate crystals obtained by cooling the aqueous solution at a temperature lower than (T 1 -10 ° C.) or higher and cooling the aqueous solution at a predetermined cooling rate or less have a small particle size. Was found to be small, and the present invention was reached.
【０００６】[0006]
【課題を解決するための手段】すなわち本発明は、過飽
和状態にある硝酸セリウム(IV)アンモニウムの水溶液
に、硝酸セリウム(IV)アンモニウムの飽和温度（Ｔ1）
以下（Ｔ1−１０℃）以上の温度で種晶を加えた後、該
水溶液を平均冷却速度２５℃／時間以下で３０℃以下ま
で冷却して、硝酸セリウム(IV)アンモニウムの結晶を析
出させることを特徴とする硝酸セリウム(IV)アンモニウ
ムの製造方法を提供するものである。That is, according to the present invention, the saturation temperature (T 1 ) of cerium (IV) ammonium nitrate is added to an aqueous solution of cerium (IV) ammonium nitrate in a supersaturated state.
After adding a seed crystal at a temperature equal to or higher than (T 1 -10 ° C.), the aqueous solution is cooled to 30 ° C. or lower at an average cooling rate of 25 ° C./hour or lower to precipitate cerium (IV) ammonium nitrate crystals. It is intended to provide a method for producing cerium (IV) ammonium nitrate, which is characterized by the following.
【０００７】[0007]
【発明の実施の形態】本発明の製造方法に適用される硝
酸セリウム(IV)アンモニウムの水溶液は、例えば酸化セ
リウム(IV)水和物または水酸化セリウム(IV)を硝酸水溶
液に溶解させたのち硝酸アンモニウムと混合して得るこ
とができる。BEST MODE FOR CARRYING OUT THE INVENTION An aqueous solution of cerium (IV) ammonium nitrate applied to the production method of the present invention is prepared by, for example, dissolving cerium (IV) oxide hydrate or cerium (IV) hydroxide in an aqueous nitric acid solution. It can be obtained by mixing with ammonium nitrate.
【０００８】酸化セリウム(IV)水和物、水酸化セリウム
(IV)はそれぞれ単独で用いられてもよいし、酸化セリウ
ム(IV)水和物と水酸化セリウム(IV)とを混合して用いら
れてもよい。酸化セリウム(IV)水和物、水酸化セリウム
(IV)は通常、水を含んだ状態で取り扱われているが、酸
化セリウム(IV)水和物、水酸化セリウム(IV)は水を含ん
だ状態であってもよい。酸化セリウム(IV)水和物、水酸
化セリウム(IV)は、１００ｇあたりの金属成分（セリウ
ムを除く）が１ｇ以下、さらには０．７ｇ以下であるこ
とが、得られる硝酸セリウム(IV)アンモニウムの結晶の
純度を高くし得る点で、好ましい。Cerium (IV) oxide hydrate, cerium hydroxide
(IV) may be used alone or as a mixture of cerium (IV) oxide hydrate and cerium (IV) hydroxide. Cerium (IV) oxide hydrate, cerium hydroxide
(IV) is usually handled in a state containing water, but cerium (IV) hydrate and cerium (IV) hydroxide may be in a state containing water. Cerium (IV) oxide hydrate and cerium (IV) hydroxide have a metal component (excluding cerium) per 100 g of 1 g or less, and more preferably 0.7 g or less. Is preferred in that the purity of the crystal of can be increased.
【０００９】硝酸水溶液としては、硝酸セリウム(IV)ア
ンモニウムの収率の点で、水溶液１００ｇあたりの硝酸
（HNO3）の含有量が５５ｇ以上、さらには６０ｇ以上で
あるものが好ましく用いられ、通常は８５ｇ以下であ
る。硝酸水溶液として濃硝酸（１００ｇ中に硝酸を９８
ｇ以上含有する水溶液）を水で希釈して用いる場合、希
釈に用いる水は、不純物の少ない水であることが好まし
く、例えばイオン交換水、超純水などが用いられる。As the nitric acid aqueous solution, those having a nitric acid (HNO 3 ) content of 55 g or more, more preferably 60 g or more per 100 g of the aqueous solution are preferably used in terms of the yield of cerium (IV) ammonium nitrate. Is 85 g or less. Concentrated nitric acid as a nitric acid aqueous solution (98 g of nitric acid in 100 g)
g) is diluted with water, the water used for dilution is preferably water with little impurities, for example, ion-exchanged water or ultrapure water.
【００１０】硝酸水溶液は、硝酸水溶液１ｋｇあたりの
金属成分が１０００ｍｇ以下、さらには１００ｍｇ以下
であることが好ましく、理想的には０である。In the aqueous nitric acid solution, the metal component per 1 kg of the aqueous nitric acid solution is preferably 1000 mg or less, more preferably 100 mg or less, and ideally 0.
【００１１】硝酸水溶液は、亜硝酸、一酸化窒素などの
ようなセリウム(IV)イオンを還元し得る成分が少ないも
のが好ましく用いられる。具体的には、硝酸水溶液１０
０ｇあたり亜硝酸および一酸化窒素の合計含有量が通常
１ｇ以下であるものが用いられ、０．５ｇ以下、さらに
は０．１ｇ以下であるものが好ましく用いられ、理想的
には０である。硝酸水溶液に含まれる亜硝酸および一酸
化窒素の合計量が１ｇを越える場合には、用いる酸化セ
リウム(IV)水和物または水酸化セリウム(IV)や、硝酸と
の反応によって生成する硝酸セリウム(IV)がこれら亜硝
酸、一酸化窒素などによって還元されてしまい、得られ
る硝酸セリウム(IV)アンモニウムの純度が低くなる。硝
酸水溶液に含まれる亜硝酸、一酸化窒素などは、例えば
窒素ガスなどの不活性ガス、空気などをバブリングする
ことによって容易に除去することができる。As the nitric acid aqueous solution, one having a small amount of components capable of reducing cerium (IV) ions, such as nitrous acid and nitric oxide, is preferably used. Specifically, the nitric acid aqueous solution 10
Those having a total content of nitrous acid and nitric oxide per 0 g of usually 1 g or less are used, and those having a total content of 0.5 g or less, more preferably 0.1 g or less are preferably used, and ideally 0. When the total amount of nitrous acid and nitric oxide contained in the aqueous nitric acid solution exceeds 1 g, cerium (IV) hydrate or cerium (IV) hydroxide to be used, or cerium nitrate ( IV) is reduced by nitrous acid, nitric oxide and the like, and the purity of the obtained cerium (IV) ammonium nitrate is lowered. Nitrite, nitric oxide and the like contained in the nitric acid aqueous solution can be easily removed by bubbling an inert gas such as nitrogen gas, air, or the like.
【００１２】硝酸水溶液は、酸化セリウム(IV)水和物ま
たは水酸化セリウム(IV)１モルあたり硝酸（HNO3）が通
常４モル以上、好ましくは７モル以上、さらに好ましく
は１０モル以上、通常２０モル以下、好ましくは１５モ
ル以下となるように使用される。硝酸が４モル以上であ
ると硝酸セリウム(IV)アンモニウムに含まれる粒子径の
小さい結晶の割合がより少なくなるが、２０モルを越え
ると容積効率の点で不利である。The aqueous nitric acid solution has a nitric acid (HNO 3 ) content of usually at least 4 moles, preferably at least 7 moles, more preferably at least 10 moles, preferably at least 10 moles, per mole of cerium (IV) oxide hydrate or cerium (IV) hydroxide. It is used in an amount of 20 mol or less, preferably 15 mol or less. When the amount of nitric acid is 4 moles or more, the ratio of crystals having a small particle diameter contained in cerium (IV) ammonium nitrate decreases, but when it exceeds 20 moles, it is disadvantageous in terms of volumetric efficiency.
【００１３】酸化セリウム(IV)水和物または水酸化セリ
ウム(IV)を硝酸水溶液に溶解させるには、例えば硝酸水
溶液と酸化セリウム(IV)水和物または水酸化セリウム(I
V)とを混合すればよく、具体的には硝酸水溶液に酸化セ
リウム(IV)水和物または水酸化セリウム(IV)を加えれば
よい。混合後、攪拌することにより、酸化セリウム(IV)
水和物または水酸化セリウム(IV)を硝酸水溶液に溶解さ
せることができる。速やかに溶解させるためには、例え
ば９０℃以上で混合することが好ましい。To dissolve cerium (IV) oxide hydrate or cerium (IV) hydroxide in an aqueous nitric acid solution, for example, an aqueous nitric acid solution and cerium (IV) hydrate or cerium (I) hydroxide
V) and, specifically, cerium (IV) oxide hydrate or cerium (IV) hydroxide may be added to an aqueous nitric acid solution. After mixing, by stirring, cerium (IV) oxide
Hydrates or cerium (IV) hydroxide can be dissolved in aqueous nitric acid. For rapid dissolution, it is preferable to mix at, for example, 90 ° C. or higher.
【００１４】酸化セリウム(IV)水和物または水酸化セリ
ウム(IV)を硝酸水溶液に溶解させたのち、フィルターで
濾過してもよい。フィルターで濾過することにより、不
溶分を除去できて、得られる硝酸セリウム(IV)アンモニ
ウムの純度を向上させることができる。フィルターとし
ては、例えば目開きが１μｍ以下であるフィルターが用
いられる。Cerium (IV) oxide hydrate or cerium (IV) hydroxide may be dissolved in an aqueous nitric acid solution, and then filtered through a filter. By filtering through a filter, insolubles can be removed, and the purity of the obtained cerium (IV) ammonium nitrate can be improved. As the filter, for example, a filter having an aperture of 1 μm or less is used.
【００１５】酸化セリウム(IV)水和物または水酸化セリ
ウム(IV)を硝酸水溶液に溶解したのち、硝酸アンモニウ
ムと混合する。混合するには、例えば酸化セリウム(IV)
水和物または水酸化セリウム(IV)を硝酸水溶液に溶解し
た後の水溶液に、硝酸アンモニウムを加えればよい。Cerium (IV) oxide hydrate or cerium (IV) hydroxide is dissolved in an aqueous nitric acid solution and then mixed with ammonium nitrate. To mix, for example, cerium (IV) oxide
Ammonium nitrate may be added to the aqueous solution obtained by dissolving the hydrate or cerium (IV) hydroxide in the aqueous nitric acid solution.
【００１６】硝酸アンモニウムは、固形物であってもよ
いが、あらかじめ水、硝酸水溶液などに溶解した水溶液
であることが、硝酸セリウム(IV)アンモニウムの結晶に
含まれる粒子径の小さい結晶の割合がより少なくなる点
で好ましい。また、硝酸アンモニウム１００ｇあたりの
金属成分が１ｇ以下、さらには０．８ｇ以下であること
が、得られる硝酸セリウム(IV)アンモニウムの結晶の純
度を高め得る点で、好ましい。Ammonium nitrate may be a solid, but it is preferable that the ammonium nitrate is an aqueous solution previously dissolved in water, an aqueous nitric acid solution or the like, so that the ratio of crystals having a small particle diameter contained in the crystals of cerium (IV) ammonium nitrate is higher. It is preferable in terms of reduction. Further, the amount of the metal component per 100 g of ammonium nitrate is preferably 1 g or less, more preferably 0.8 g or less from the viewpoint that the purity of the obtained cerium (IV) ammonium nitrate crystal can be increased.
【００１７】硝酸アンモニウムの水溶液を用いる場合、
該水溶液はフィルターで濾過された後に用いられてもよ
い。フィルターで濾過することにより、硝酸アンモニウ
ムに含まれる不純物を除去して、より純度の高い硝酸セ
リウム(IV)アンモニウムを得ることができる。フィルタ
ーとしては、例えば目開きが１μｍ以下であるフィルタ
ーが用いられる。When an aqueous solution of ammonium nitrate is used,
The aqueous solution may be used after being filtered. By filtering through a filter, impurities contained in ammonium nitrate can be removed, and cerium (IV) ammonium nitrate having higher purity can be obtained. As the filter, for example, a filter having an aperture of 1 μm or less is used.
【００１８】硝酸アンモニウムの使用量は、先に使用し
た酸化セリウム(IV)水和物または水酸化セリウム(IV)１
モルあたり通常２モル倍以上であるが、混合した後の硝
酸セリウム(IV)アンモニウムの水溶液における硝酸と水
との合計量１００ｇに含まれる硝酸（HNO3）が４０ｇ以
上７０ｇ以下となるように調整されることが好ましい。
硝酸アンモニウムとしてその水溶液を用いる場合、混合
した後の硝酸セリウム(IV)アンモニウムの水溶液に含ま
れる硝酸を上記範囲とするためには、通常は、硝酸アン
モニウム水溶液における硝酸アンモニウムの使用量、水
の使用量を適宜選択すればよい。また、硝酸アンモニウ
ムを固形物のまま用いる場合には、酸化セリウム(IV)水
和物または水酸化セリウム(IV)を硝酸水溶液に溶解した
後の硝酸の濃度を、硝酸アンモニウムと混合した後の硝
酸の濃度が上記範囲となるように、適宜調整すればよ
い。The amount of ammonium nitrate used depends on the cerium (IV) oxide hydrate or cerium (IV) hydroxide used previously.
It is usually at least 2 moles per mole, but the nitric acid (HNO 3 ) contained in the total amount of 100 g of nitric acid and water in the mixed aqueous solution of cerium (IV) ammonium nitrate is adjusted to be 40 g or more and 70 g or less. Is preferably performed.
When using the aqueous solution as ammonium nitrate, in order to make the nitric acid contained in the aqueous solution of cerium (IV) ammonium nitrate after mixing into the above range, usually, the amount of ammonium nitrate used in the aqueous ammonium nitrate solution and the amount of water used are appropriately adjusted. Just choose. When ammonium nitrate is used as a solid, the concentration of nitric acid after dissolving cerium (IV) oxide hydrate or cerium (IV) hydroxide in an aqueous nitric acid solution is adjusted to the concentration of nitric acid after mixing with ammonium nitrate. May be adjusted appropriately so as to fall within the above range.
【００１９】硝酸アンモニウムと混合する際の温度は、
混合時やその後に硝酸セリウム(IV)アンモニウムが析出
しない温度とすることが好ましく、例えば９０℃以上で
混合することが好ましい。また、混合時やその後に硝酸
セリウム(IV)アンモニウムが析出した場合には、加熱し
て、析出した硝酸セリウム(IV)アンモニウムを完全に溶
解させてもよい。The temperature for mixing with ammonium nitrate is as follows:
It is preferable that the temperature be such that ammonium cerium (IV) nitrate does not precipitate during or after mixing, and for example, it is preferable to mix at 90 ° C. or higher. When cerium (IV) ammonium nitrate precipitates during or after mixing, heating may be performed to completely dissolve the precipitated cerium (IV) ammonium nitrate.
【００２０】本発明の製造方法では、硝酸セリウム(IV)
アンモニウムの水溶液に種晶を加える。種晶を加える際
の水溶液の温度は、硝酸セリウム(IV)アンモニウムの飽
和温度（Ｔ1）以下である。Ｔ1を越える温度では、加え
た種晶が溶解してしまう場合がある。また、種晶を加え
る際の水溶液の温度は（Ｔ1−１０℃）以上の温度であ
る。（Ｔ1−１０℃）未満の温度では、粒子径の小さい
結晶の割合が多くなる傾向にある。種晶を加える際の温
度として具体的には、硝酸セリウム(IV)アンモニウムの
濃度、硝酸の濃度、硝酸アンモニウムの濃度などによっ
て異なるが、例えば８０℃以上１００℃以下程度であ
る。In the production method of the present invention, cerium (IV) nitrate
Seed the aqueous ammonium solution. The temperature of the aqueous solution at the time of adding the seed crystal is equal to or lower than the saturation temperature (T 1 ) of cerium (IV) ammonium nitrate. At temperatures exceeding T 1, there is a case where the added seed crystals had dissolved. The temperature of the aqueous solution when the seed crystal is added is (T 1 -10 ° C.) or higher. At a temperature lower than (T 1 -10 ° C.), the proportion of crystals having a small particle size tends to increase. The temperature at which the seed crystal is added specifically depends on the concentration of cerium (IV) ammonium nitrate, the concentration of nitric acid, the concentration of ammonium nitrate, etc., but is, for example, about 80 ° C. or more and 100 ° C. or less.
【００２１】飽和温度は、水溶液の硝酸セリウム(IV)ア
ンモニウム濃度が飽和となる温度であって、例えば該水
溶液に加えた少量の硝酸セリウム(IV)アンモニウムの結
晶が溶解しない温度の上限として求めることができる。The saturation temperature is a temperature at which the concentration of cerium (IV) ammonium nitrate in the aqueous solution becomes saturated, and is determined, for example, as the upper limit of the temperature at which a small amount of cerium (IV) ammonium nitrate crystals added to the aqueous solution does not dissolve. Can be.
【００２２】硝酸セリウム(IV)アンモニウムの水溶液を
Ｔ1以下（Ｔ1−１０℃）以上とするには、例えば硝酸セ
リウム(IV)アンモニウムを完全に溶解させた状態から、
徐々に冷却すればよい。Ｔ1以下（Ｔ1−１０℃）以上と
することによって、硝酸セリウム(IV)アンモニウムの結
晶が析出してもよく、硝酸セリウム(IV)アンモニウムの
水溶液は飽和状態または過飽和状態となる。In order to make the aqueous solution of ammonium cerium (IV) nitrate less than T 1 (T 1 -10 ° C.) or more, for example, from a state in which cerium (IV) ammonium nitrate is completely dissolved,
What is necessary is just to cool gradually. By setting the temperature to T 1 or less (T 1 −10 ° C.) or more, crystals of cerium (IV) ammonium nitrate may precipitate, and the aqueous solution of cerium (IV) ammonium nitrate becomes saturated or supersaturated.
【００２３】種晶は、硝酸セリウム(IV)アンモニウムの
結晶を用いることが好ましく、硝酸セリウム(IV)アンモ
ニウムの水溶液中１００ｇあたり通常０．００５ｇ以
上、好ましくは０．０１ｇ以上程度、通常０．５ｇ以
下、好ましくは０．１ｇ以下程度である。As the seed crystal, it is preferable to use a crystal of cerium (IV) ammonium nitrate, and usually 0.005 g or more, preferably about 0.01 g or more, and usually 0.5 g or more per 100 g of an aqueous solution of cerium (IV) ammonium nitrate. Or less, preferably about 0.1 g or less.
【００２４】硝酸セリウム(IV)アンモニウムの水溶液
は、飽和状態または過飽和状態であるので、種晶は該水
溶液には溶解することなく、固体のまま水溶液中に存在
する。また、硝酸セリウム(IV)アンモニウムの水溶液に
種晶を加えた後、冷却を開始する前に、結晶が析出して
もよい。Since the aqueous solution of cerium (IV) ammonium nitrate is in a saturated state or a supersaturated state, the seed crystals do not dissolve in the aqueous solution but exist as a solid in the aqueous solution. Further, after the seed crystal is added to the aqueous solution of cerium (IV) ammonium nitrate, the crystal may be precipitated before cooling is started.
【００２５】種晶を加えた後、硝酸セリウム(IV)アンモ
ニウムの水溶液を３０℃以下に冷却して、硝酸セリウム
(IV)アンモニウムの結晶を析出させる。冷却は、平均冷
却速度２５℃／時間以下、好ましくは１５℃／時間以下
で３０℃以下まで行なう。平均冷却速度が２５℃／時間
を越えると、粒子径の小さい硝酸セリウム(IV)アンモニ
ウムの結晶が多く生成する傾向にある。また平均冷却速
度の下限は特に限定されないが、あまりにも小さいと冷
却に長時間を要するので、通常は５℃／時間以上であ
る。After the seed crystal is added, the aqueous solution of cerium (IV) ammonium nitrate is cooled to 30 ° C. or less,
(IV) Precipitate ammonium crystals. Cooling is performed at an average cooling rate of 25 ° C./hour or less, preferably 15 ° C./hour or less, to 30 ° C. or less. If the average cooling rate exceeds 25 ° C./hour, a large number of cerium (IV) ammonium nitrate crystals having a small particle size tend to be formed. The lower limit of the average cooling rate is not particularly limited. However, if the average cooling rate is too small, it takes a long time for cooling, so that it is usually 5 ° C./hour or more.
【００２６】種晶を加えた後の冷却は、平均冷却速度が
上記範囲となるように冷却すればよく、例えば種晶を加
えた後、一定の冷却速度で３０℃以下まで冷却してもよ
い。また、種晶を加えた後、５０℃以上９０℃以下で±
５℃の温度範囲に３０分以上保持し、次いで３０℃以下
に冷却することが好ましい。ここで、種晶を加えた後、
±５℃の温度範囲に維持する時間は３０分程度であり、
その温度は５０℃以上９０℃以下の範囲から適宜選択さ
れる。The cooling after the seed crystal is added may be such that the average cooling rate is within the above range. For example, after the seed crystal is added, the cooling may be performed at a constant cooling rate to 30 ° C. or less. . Further, after adding a seed crystal, the temperature is ± 50 ° C or more and 90 ° C or less.
It is preferable to maintain the temperature in a temperature range of 5 ° C. for 30 minutes or more, and then cool the temperature to 30 ° C. or less. Here, after adding the seed crystal,
The time to maintain the temperature range of ± 5 ° C is about 30 minutes,
The temperature is appropriately selected from the range of 50 ° C. or more and 90 ° C. or less.
【００２７】かくして３０℃以下に冷却することによっ
て得られる硝酸セリウム(IV)アンモニウムの結晶はその
粒子径が大きいものが多く、粒子径の小さい結晶は少な
い。The crystals of cerium (IV) ammonium nitrate obtained by cooling to 30 ° C. or less often have a large particle size and few crystals with a small particle size.
【００２８】析出した硝酸セリウム(IV)アンモニウムの
結晶は、例えば冷却後の混合物を濾過する方法によっ
て、容易に取り出すことができる。濾過は、３０℃以下
に冷却した後、直ちに行なってもよいが、３０℃以下で
±５℃の温度範囲に０．５時間以上保温したのちに行な
うことが好ましい。濾過は、例えばフィルターによる濾
過であってもよいし、遠心分離による濾過であってもよ
い。The precipitated cerium (IV) ammonium nitrate crystals can be easily taken out, for example, by filtering the cooled mixture. The filtration may be carried out immediately after cooling to 30 ° C. or lower, but it is preferable to carry out the filtration after keeping the temperature at 30 ° C. or lower in a temperature range of ± 5 ° C. for 0.5 hour or more. The filtration may be, for example, filtration by a filter or filtration by centrifugation.
【００２９】濾過後、得られた結晶を、例えば硝酸水溶
液などで洗浄してもよい。洗浄に用いる硝酸水溶液とし
ては通常、該水溶液１００ｇあたり硝酸を３０ｇ以上含
有するものが用いられる。洗浄後、乾燥してもよい。乾
燥するには、例えば通風乾燥、減圧乾燥などの通常の方
法で乾燥すればよく、乾燥温度は、通常０℃以上１５０
℃以下の温度範囲から適宜選択される。After filtration, the obtained crystals may be washed with, for example, an aqueous solution of nitric acid. As the nitric acid aqueous solution used for washing, a solution containing 30 g or more of nitric acid per 100 g of the aqueous solution is usually used. After washing, it may be dried. Drying may be performed by a usual method such as ventilation drying or reduced pressure drying.
It is appropriately selected from a temperature range of not more than ° C.
【００３０】濾過後、得られた濾液は、硝酸、硝酸アン
モニウム、硝酸セリウム(IV)アンモニウムを含んでいる
が、かかる濾液は、硝酸水溶液の濃度の調整に用いるこ
とができ、硝酸アンモニウムとして硝酸アンモニウム水
溶液を用いる場合には、該硝酸アンモニウム水溶液の濃
度の調整に用いることもできる。After filtration, the obtained filtrate contains nitric acid, ammonium nitrate and cerium (IV) ammonium nitrate. Such a filtrate can be used for adjusting the concentration of an aqueous nitric acid solution, and an aqueous ammonium nitrate solution is used as ammonium nitrate. In this case, it can be used for adjusting the concentration of the ammonium nitrate aqueous solution.
【００３１】[0031]
【発明の効果】本発明の製造方法により得られる硝酸セ
リウム(IV)アンモニウムは、粒子径の小さい結晶が少な
く、ほとんどが粒子径の大きな結晶であるので、取り扱
いが比較的容易である。The cerium (IV) ammonium nitrate obtained by the production method of the present invention is relatively easy to handle because it has few crystals having a small particle diameter and most of the crystals have a large particle diameter.
【００３２】[0032]
【実施例】以下、実施例により本発明をより詳細に説明
するが、本発明は、かかる実施例によって限定されるも
のではない。The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
【００３３】なお、各実施例および比較例で得た硝酸セ
リウム(IV)アンモニウムの水溶液の飽和温度（Ｔ1）、
硝酸セリウム(IV)アンモニウムの結晶の粒子径分布は、
以下の方法で求めた。 （１）硝酸セリウム(IV)アンモニウムの水溶液の飽和温
度（Ｔ1） 各実施例および比較例と同様に操作して得た水溶液（透
明で懸濁は認められなかった）を一定温度（Ｔ0）に維
持し、これに該水溶液１００ｇあたり硝酸セリウム(IV)
アンモニウムの結晶（粒子径は１００μｍ〜１０００μ
ｍ）０．０２５ｇを加えたときに、該結晶が溶解しなか
った温度（Ｔ0）の最大値を飽和温度（Ｔ1）とした。 （２）硝酸セリウム〔IV〕アンモニウムの結晶の粒子径
分布 目開き７５μｍ、１０６μｍ、１５０μｍ、２１２μ
ｍ、３００μｍ、５００μｍ、７１０μｍの篩を用い
て、結晶の全量に占める粒子径７５μｍ以下の粒子の質
量分率（％）、粒子径１０６μｍ以下の粒子の質量分率
（％）、粒子径１５０μｍ以下の粒子の質量分率
（％）、粒子径２１２μｍ以下の粒子の質量分率
（％）、粒子径３００μｍ以下の粒子の質量分率
（％）、粒子径５００μｍ以下の粒子の質量分率
（％）、粒子径７１０μｍ以下の粒子の質量分率（％）
をそれぞれ求めた。The saturation temperature (T 1 ) of the aqueous solution of cerium (IV) ammonium nitrate obtained in each of the examples and comparative examples,
The particle size distribution of cerium (IV) ammonium nitrate crystals is
It was determined by the following method. (1) Saturation temperature (T 1 ) of an aqueous solution of cerium (IV) ammonium nitrate (T 1 ) An aqueous solution (transparent and no suspension was observed) obtained in the same manner as in each of Examples and Comparative Examples was heated at a constant temperature (T 0). ), And cerium (IV) nitrate per 100 g of the aqueous solution
Ammonium crystals (particle size is 100 μm to 1000 μm
m) The maximum temperature (T 0 ) at which the crystals did not dissolve when 0.025 g was added was defined as the saturation temperature (T 1 ). (2) Particle size distribution of cerium [IV] ammonium nitrate crystals 75 μm, 106 μm, 150 μm, 212 μm
The mass fraction (%) of particles having a particle diameter of 75 μm or less, the mass fraction (%) of particles having a particle diameter of 106 μm or less, and the particle diameter of 150 μm or less are occupied by using sieves having m, 300 μm, 500 μm, and 710 μm. , The mass fraction (%) of particles having a particle diameter of 212 μm or less, the mass fraction (%) of particles having a particle diameter of 300 μm or less, and the mass fraction (%) of particles having a particle diameter of 500 μm or less. ), Mass fraction (%) of particles having a particle diameter of 710 μm or less
Was asked respectively.
【００３４】実施例１ ９８％硝酸（１００ｇ中に硝酸を９８ｇ含有する）およ
びイオン交換水を混合した後、窒素ガスをバブリングさ
せて７５％硝酸水溶液〔１００ｇ中に硝酸（HNO3）を７
５ｇ含有し、亜硝酸を０．０７ｇ含有する〕を調整し、
この７５％硝酸２３８．８ｇにイオン交換水１３．９ｇ
を加えたのち、酸化セリウム(IV)水和物（結晶水以外に
質量分率で２２．９％の水を含み、不純物は０．５％以
下）５５．２ｇを加え、攪拌しながら１００℃まで昇温
して、攪拌しながら同温度で１時間保温して酸化セリウ
ム(IV)水和物を完全に溶解させた。その後、室温まで冷
却し、目開き０．２μｍのメンブランフィルターで濾過
して濾液を得た。この濾液を９８℃に昇温し、９５℃〜
９８℃の温度範囲を維持しながら硝酸アンモニウム水溶
液〔硝酸アンモニウム（純度９９．８％）５９．５ｇを
イオン交換水４３．６ｇに溶解した水溶液〕を滴下して
加えて硝酸セリウム(IV)アンモニウムの水溶液を得た。
この水溶液の飽和温度（Ｔ1）は９５℃であった。Example 1 After 98% nitric acid (98 g of nitric acid was contained in 100 g) and ion-exchanged water were mixed, nitrogen gas was bubbled thereinto to make a 75% aqueous nitric acid solution [7 g of nitric acid (HNO 3 ) in 100 g.
Containing 5 g and containing 0.07 g of nitrous acid].
233.9 g of this 75% nitric acid was added to 13.9 g of ion-exchanged water.
Was added, and 55.2 g of cerium (IV) hydrate (including water of 22.9% by mass in addition to the water of crystallization and impurities of 0.5% or less) was added, and the mixture was stirred at 100 ° C. The cerium (IV) hydrate was completely dissolved by heating at the same temperature for 1 hour while stirring. Thereafter, the mixture was cooled to room temperature and filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate was heated to 98 ° C,
An aqueous solution of ammonium nitrate (an aqueous solution in which 59.5 g of ammonium nitrate (purity: 99.8%) was dissolved in 43.6 g of ion-exchanged water) was added dropwise while maintaining the temperature range of 98 ° C., and an aqueous solution of ammonium cerium (IV) nitrate was added. Obtained.
The saturation temperature (T 1 ) of this aqueous solution was 95 ° C.
【００３５】その後、上記で得た水溶液を９０℃に冷却
したところ、この水溶液は透明であり、懸濁していなか
った。冷却後の硝酸セリウム(IV)アンモニウムの水溶液
を９０℃に維持したまま、種晶（硝酸セリウム(IV)アン
モニウムの結晶、粒子径は１００μｍ〜１０００μｍ）
０．１ｇを加えたところ、析出物は観察できなかった。
その後、直ちに１時間かけて８０℃まで冷却し、同温度
を１時間保った後、６時間かけて２０℃まで冷却した。
ここで９０℃から２０℃までの冷却に要した時間は合計
８時間であり、平均冷却速度は８．７５℃／時間であ
る。Thereafter, when the aqueous solution obtained above was cooled to 90 ° C., the aqueous solution was transparent and was not suspended. Seed crystals (crystals of cerium (IV) ammonium nitrate, particle diameter of 100 μm to 1000 μm) while maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C.
When 0.1 g was added, no precipitate could be observed.
Then, the mixture was immediately cooled to 80 ° C. over 1 hour, kept at the same temperature for 1 hour, and then cooled to 20 ° C. over 6 hours.
Here, the time required for cooling from 90 ° C. to 20 ° C. is 8 hours in total, and the average cooling rate is 8.75 ° C./hour.
【００３６】その後、２０℃で１時間保温し、フィルタ
ーを用いて濾過して、硝酸セリウム(IV)アンモニウムの
結晶（１３１．６ｇ）を得た。この硝酸セリウム(IV)ア
ンモニウムの結晶２ｇを１１０℃で加熱し、３０秒間の
質量の減少量が３ｍｇとなるまで乾燥して乾燥減量を求
めたところ、３．３％であり、乾燥後の純度は９９．１
％であった。この結晶の粒子径分布の評価結果を表１に
示す。Thereafter, the mixture was kept at 20 ° C. for 1 hour and filtered with a filter to obtain cerium (IV) ammonium nitrate crystals (131.6 g). 2 g of this cerium (IV) ammonium nitrate crystal was heated at 110 ° C. and dried until the weight loss in 30 seconds was 3 mg, and the loss on drying was determined. Is 99.1
%Met. Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００３７】実施例２ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中に硝酸を７５ｇ含有し、亜硝酸は含まな
い。〕１８２．３ｇにイオン交換水７０．７ｇを加えた
のち、酸化セリウム(IV)水和物（結晶水以外に質量分率
で２３．１％の水を含み、不純物は０．５％以下）５
５．３ｇを加え、攪拌しながら１００℃まで昇温して、
攪拌しながら同温度で１時間保温して酸化セリウム(IV)
水和物を完全に溶解させた。その後、室温まで冷却し、
目開き０．２μｍのメンブランフィルターで濾過して濾
液を得た。この濾液を９８℃に昇温し、９５℃〜９８℃
の温度範囲を維持しながら硝酸アンモニウム水溶液〔硝
酸アンモニウム（純度９９．８％）４９．６ｇをイオン
交換水３３．０ｇに溶解した水溶液〕を滴下して加えて
硝酸セリウムアンモニウムの水溶液を得た。この水溶液
の飽和温度（Ｔ1）は９５℃であった。Example 2 A 75% aqueous nitric acid solution prepared and operated in the same manner as in Example 1 [contains 75 g of nitric acid in 100 g and does not contain nitrous acid. ] After adding 70.7 g of ion-exchanged water to 182.3 g, cerium (IV) oxide hydrate (including water of 23.1% by mass fraction besides water of crystallization and impurities of 0.5% or less) 5
5.3 g was added, and the temperature was raised to 100 ° C. while stirring.
Incubate for 1 hour at the same temperature while stirring, and cerium (IV) oxide
The hydrate was completely dissolved. Then cool to room temperature,
The solution was filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The temperature of the filtrate is raised to 98 ° C, and
While maintaining the above temperature range, an aqueous solution of ammonium nitrate [an aqueous solution in which 49.6 g of ammonium nitrate (purity: 99.8%) was dissolved in 33.0 g of ion-exchanged water] was added dropwise to obtain an aqueous solution of cerium ammonium nitrate. The saturation temperature (T 1 ) of this aqueous solution was 95 ° C.
【００３８】その後、上記で得た硝酸セリウム(IV)アン
モニウムの水溶液を９０℃に冷却したところ、透明で懸
濁していなかった。冷却後の硝酸セリウム(IV)アンモニ
ウムの水溶液を９０℃に維持したまま、種晶（硝酸セリ
ウム(IV)アンモニウムの結晶、粒子径は１００μｍ〜１
０００μｍ）０．１ｇを加えところ、析出物は観察でき
なかった。その後、直ちに１時間かけて８０℃まで冷却
し、同温度を１時間保った後、６時間かけて２０℃まで
冷却した。ここで９０℃から２０℃までの冷却に要した
時間は合計８時間であり、平均冷却速度は８．７５℃／
時間である。Thereafter, when the aqueous solution of cerium (IV) ammonium nitrate obtained above was cooled to 90 ° C., it was clear and not suspended. While maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C., a seed crystal (crystal of cerium (IV) ammonium nitrate, particle diameter of 100 μm to 1 μm) was used.
When 0.1 g of 000 μm) was added, no precipitate was observed. Then, the mixture was immediately cooled to 80 ° C. over 1 hour, kept at the same temperature for 1 hour, and then cooled to 20 ° C. over 6 hours. Here, the time required for cooling from 90 ° C. to 20 ° C. is a total of 8 hours, and the average cooling rate is 8.75 ° C. /
Time.
【００３９】その後、２０℃で１時間保温し、フィルタ
ーを用いて濾過して、硝酸セリウム(IV)アンモニウムの
結晶（１２９．５ｇ）を得た。実施例１と同様にして求
めた硝酸セリウム(IV)アンモニウムの結晶の乾燥減量は
２．８％であり、乾燥後の純度は９９．０％であった。
この結晶の粒子径分布の評価結果を表１に示す。Thereafter, the mixture was kept at 20 ° C. for 1 hour and filtered with a filter to obtain cerium (IV) ammonium nitrate crystals (129.5 g). The loss on drying of the cerium (IV) ammonium nitrate crystals determined in the same manner as in Example 1 was 2.8%, and the purity after drying was 99.0%.
Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００４０】実施例３ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中に硝酸を７５ｇ含有し、亜硝酸を含まな
い。〕２３８．８ｇにイオン交換水１３．０ｇを加えた
のち、酸化セリウム(IV)水和物（結晶水以外に質量分率
で２４．１％の水を含み、不純物は０．５％以下）５
６．１ｇを加え、攪拌しながら１００℃まで昇温して、
攪拌しながら同温度で１時間保温して酸化セリウム(IV)
水和物を完全に溶解させた。その後、室温まで冷却し、
目開き０．２μｍのメンブランフィルターで濾過して濾
液を得た。この濾液を９８℃に昇温し、９５℃〜９８℃
の温度範囲を維持しながら硝酸アンモニウム水溶液〔硝
酸アンモニウム（純度９９．８％）４３．６ｇをイオン
交換水４３．６ｇに溶解した水溶液〕を滴下して加えて
硝酸セリウムアンモニウムの水溶液を得た。この水溶液
の飽和温度（Ｔ1）は９５℃であった。Example 3 A 75% aqueous nitric acid solution prepared and operated in the same manner as in Example 1 [contains 75 g of nitric acid in 100 g and does not contain nitrous acid. ] After adding 13.0 g of ion-exchanged water to 238.8 g, cerium (IV) oxide hydrate (including water of 24.1% by mass in addition to water of crystallization and impurities of 0.5% or less) 5
6.1 g was added, and the temperature was raised to 100 ° C. while stirring,
Incubate for 1 hour at the same temperature while stirring, and cerium (IV) oxide
The hydrate was completely dissolved. Then cool to room temperature,
Filtration was performed with a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate is heated to 98 ° C., and
While maintaining the above temperature range, an aqueous solution of ammonium nitrate (an aqueous solution in which 43.6 g of ammonium nitrate (purity: 99.8%) was dissolved in 43.6 g of ion-exchanged water) was added dropwise to obtain an aqueous solution of cerium ammonium nitrate. The saturation temperature (T 1 ) of this aqueous solution was 95 ° C.
【００４１】その後、上記で得た硝酸セリウム(IV)アン
モニウムの水溶液を９０℃に冷却したところ、透明で懸
濁していなかった。冷却後の硝酸セリウム(IV)アンモニ
ウムの水溶液を９０℃に維持したまま、種晶（硝酸セリ
ウム(IV)アンモニウムの結晶、粒子径は１００μｍ〜１
０００μｍ）０．１ｇを加えところ、析出物は観察でき
なかった。その後、直ちに３時間かけて６０℃まで冷却
し、同温度を１時間保った後、４時間かけて２０℃まで
冷却した。ここで９０℃から２０℃までの冷却に要した
時間は合計８時間であり、平均冷却速度は８．７５℃／
時間である。Thereafter, when the aqueous solution of cerium (IV) ammonium nitrate obtained above was cooled to 90 ° C., it was clear and not suspended. While maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C., a seed crystal (crystal of cerium (IV) ammonium nitrate, particle diameter of 100 μm to 1 μm) was used.
When 0.1 g of 000 μm) was added, no precipitate was observed. Then, the mixture was immediately cooled to 60 ° C. over 3 hours, kept at the same temperature for 1 hour, and then cooled to 20 ° C. over 4 hours. Here, the time required for cooling from 90 ° C. to 20 ° C. is a total of 8 hours, and the average cooling rate is 8.75 ° C. /
Time.
【００４２】その後、２０℃で１時間保温し、フィルタ
ーを用いて濾過して、硝酸セリウム(IV)アンモニウムの
結晶（１１７．０ｇ）を得た。実施例１と同様にして求
めた硝酸セリウム(IV)アンモニウムの結晶の乾燥減量は
１．８％であり、乾燥後の純度は９９．２％であった。
この結晶の粒子径分布の評価結果を表１に示す。Thereafter, the mixture was kept at 20 ° C. for 1 hour and filtered using a filter to obtain cerium (IV) ammonium nitrate crystals (117.0 g). The loss on drying of the cerium (IV) ammonium nitrate crystals obtained in the same manner as in Example 1 was 1.8%, and the purity after drying was 99.2%.
Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００４３】実施例４ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中に硝酸を７５ｇ含有し、亜硝酸を０．１９
ｇ含有する。〕２３８．１ｇにイオン交換水１３．７ｇ
を加えたのち、酸化セリウム(IV)水和物（結晶水以外に
質量分率で２３．２％の水を含み、不純物は０．５％以
下）５４．８ｇを加え、攪拌しながら１００℃まで昇温
して、攪拌しながら同温度で１時間保温して酸化セリウ
ム(IV)水和物を完全に溶解させた。その後、室温まで冷
却し、目開き０．２μｍのメンブランフィルターで濾過
して濾液を得た。この濾液を９８℃に昇温し、９５℃〜
９８℃の温度範囲を維持しながら硝酸アンモニウム水溶
液〔硝酸アンモニウム（純度９９．８％）４３．１ｇを
イオン交換水３３．０ｇに溶解した水溶液〕を滴下して
加えて硝酸セリウムアンモニウムの水溶液を得た。この
水溶液の飽和温度（Ｔ 1）は９５℃であった。Example 4 An aqueous 75% nitric acid solution prepared and operated in the same manner as in Example 1
[75 g of nitric acid is contained in 100 g, and nitric acid is 0.19
g. 233.7 g of 13.7 g of ion-exchanged water
Cerium (IV) oxide hydrate (other than water of crystallization)
Contains 23.2% water by mass fraction and less than 0.5% impurities
Bottom) Add 54.8 g and raise the temperature to 100 ° C with stirring
Then, keep stirring at the same temperature for 1 hour while stirring to remove cerium oxide.
(IV) hydrate was completely dissolved. Then cool to room temperature
And filtered through a 0.2 μm mesh filter
Thus, a filtrate was obtained. The filtrate was heated to 98 ° C,
Ammonium nitrate aqueous solution while maintaining the temperature range of 98 ° C
Liquid [43.1 g of ammonium nitrate (purity 99.8%)
Aqueous solution dissolved in 33.0 g of ion-exchanged water]
In addition, an aqueous solution of cerium ammonium nitrate was obtained. this
Saturation temperature of aqueous solution (T 1) Was 95 ° C.
【００４４】その後、上記で得た硝酸セリウム(IV)アン
モニウムの水溶液を９０℃に冷却したところ、透明で懸
濁していなかった。冷却後の硝酸セリウム(IV)アンモニ
ウムの水溶液を９０℃に維持したまま、種晶（硝酸セリ
ウム(IV)アンモニウムの結晶、粒子径は１００μｍ〜１
０００μｍ）０．１ｇを加えたところ、析出物は観察で
きなかった。その後、直ちに７時間かけて同じ冷却速度
で２０℃まで冷却した。ここで９０℃から２０℃までの
冷却に要した時間は７時間であり、平均冷却速度は１０
℃／時間である。Thereafter, when the aqueous solution of cerium (IV) ammonium nitrate obtained above was cooled to 90 ° C., it was clear and not suspended. While maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C., a seed crystal (crystal of cerium (IV) ammonium nitrate, particle diameter of 100 μm to 1 μm) was used.
(000 μm), no precipitate was observed. Thereafter, the mixture was immediately cooled to 20 ° C. at the same cooling rate over 7 hours. Here, the time required for cooling from 90 ° C. to 20 ° C. is 7 hours, and the average cooling rate is 10 hours.
° C / hour.
【００４５】その後、直ちにフィルターを用いて濾過し
て、硝酸セリウム(IV)アンモニウムの結晶（１１４．０
ｇ）を得た。実施例１と同様にして求めた硝酸セリウム
(IV)アンモニウムの結晶の乾燥減量は２．３％であり、
乾燥後の純度は９９．５％であった。この結晶の粒子径
分布の評価結果を表１に示す。Then, the mixture was immediately filtered using a filter to remove cerium (IV) ammonium nitrate crystals (114.0).
g) was obtained. Cerium nitrate obtained in the same manner as in Example 1.
(IV) the loss on drying of the ammonium crystals is 2.3%,
The purity after drying was 99.5%. Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００４６】実施例５ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中に硝酸を７５ｇ含有し、亜硝酸を０．６２
ｇ含有する〕２３８．８ｇにイオン交換水１３．９ｇを
加えて硝酸水溶液を得た。この硝酸水溶液に含まれる亜
硝酸は０．９ｇであった。この硝酸水溶液に酸化セリウ
ム(IV)水和物（結晶水以外に質量分率で２２．９％の水
を含み、不純物は０．５％以下）５５．２ｇを加え、攪
拌しながら１００℃まで昇温して、攪拌しながら同温度
で１時間保温して酸化セリウム(IV)水和物を完全に溶解
させた。その後、室温まで冷却し、目開き０．２μｍの
メンブランフィルターで濾過して濾液を得た。この濾液
を９８℃に昇温し、９５℃〜９８℃の温度範囲を維持し
ながら硝酸アンモニウム水溶液〔硝酸アンモニウム（純
度９９．８％）４３．６ｇをイオン交換水４３．６ｇに
溶解した水溶液〕を滴下して加えて硝酸セリウムアンモ
ニウムの水溶液を得た。この水溶液の飽和温度（Ｔ1）
は、９５℃であった。Example 5 A 75% aqueous nitric acid solution prepared by operating in the same manner as in Example 1 [75 g of nitric acid is contained in 100 g, and 0.62
13.9 g of ion-exchanged water was added to 238.8 g of the mixture to obtain a nitric acid aqueous solution. The nitric acid contained in the aqueous nitric acid solution was 0.9 g. 55.2 g of cerium (IV) oxide hydrate (including water of 22.9% by mass fraction in addition to water of crystallization and impurities of 0.5% or less) is added to the aqueous nitric acid solution, and the mixture is stirred to 100 ° C. while stirring. The temperature was raised, and the temperature was kept at the same temperature for 1 hour with stirring to completely dissolve the cerium (IV) oxide hydrate. Thereafter, the mixture was cooled to room temperature and filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate was heated to 98 ° C., and an aqueous ammonium nitrate solution (an aqueous solution in which 43.6 g of ammonium nitrate (purity: 99.8%) was dissolved in 43.6 g of ion-exchanged water) was added dropwise while maintaining the temperature range of 95 ° C. to 98 ° C. Then, an aqueous solution of cerium ammonium nitrate was obtained. Saturation temperature of this aqueous solution (T 1 )
Was 95 ° C.
【００４７】その後、上記で得た硝酸セリウム(IV)アン
モニウムの水溶液を９０℃に冷却したところ、透明で懸
濁していなかった。冷却後の硝酸セリウム(IV)アンモニ
ウムの水溶液を９０℃に維持したまま、種晶（硝酸セリ
ウム(IV)アンモニウムの結晶、粒子径は１００μｍ〜１
０００μｍ）０．１ｇを加えたところ、析出物は観察で
きなかった。その後、直ちに１時間かけて８０℃まで冷
却し、同温度を１時間保った後、６時間かけて２０℃ま
で冷却した。ここで９０℃から２０℃までの冷却に要し
た時間は合計８時間であり、平均冷却速度は８．７５℃
／時間である。Thereafter, the aqueous solution of cerium (IV) ammonium nitrate obtained above was cooled to 90 ° C. and found to be transparent and not suspended. While maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C., a seed crystal (crystal of cerium (IV) ammonium nitrate, particle diameter of 100 μm to 1 μm) was used.
(000 μm), no precipitate was observed. Then, the mixture was immediately cooled to 80 ° C. over 1 hour, kept at the same temperature for 1 hour, and then cooled to 20 ° C. over 6 hours. Here, the time required for cooling from 90 ° C. to 20 ° C. is a total of 8 hours, and the average cooling rate is 8.75 ° C.
/ Hour.
【００４８】その後、２０℃で１時間保温し、フィルタ
ーを用いて濾過して、硝酸セリウム(IV)アンモニウムの
結晶（１０６．５ｇ）を得た。実施例１と同様にして求
めた硝酸セリウム(IV)アンモニウムの結晶の乾燥減量は
２．４％であり、乾燥後の純度は９９．７％であった。
この結晶の粒子径分布の評価結果を表１に示す。Thereafter, the mixture was kept at 20 ° C. for 1 hour and filtered with a filter to obtain cerium (IV) ammonium nitrate crystals (106.5 g). The loss on drying of the cerium (IV) ammonium nitrate crystals determined in the same manner as in Example 1 was 2.4%, and the purity after drying was 99.7%.
Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００４９】実施例６ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中硝酸を７５ｇ含有し、亜硝酸を０．２３ｇ
含有する。〕２３８．８ｇにイオン交換水１４．９ｇを
加えたのち、酸化セリウム(IV)水和物（結晶水以外に質
量分率で２１．５％の水を含み、不純物は０．５％以
下）５４．２ｇを加え、攪拌しながら１００℃まで昇温
して、攪拌しながら同温度で１時間保温して酸化セリウ
ム(IV)水和物を完全に溶解させた。その後、室温まで冷
却し、目開き０．２μｍのメンブランフィルターで濾過
して濾液を得た。この濾液を９８℃に昇温し、９５℃〜
９８℃の温度範囲を維持しながら硝酸アンモニウム水溶
液〔硝酸アンモニウム（純度９９．８％）４９．１ｇを
イオン交換水３２．６ｇに溶解した水溶液〕を滴下して
加えて硝酸セリウムアンモニウムの水溶液を得た。この
水溶液の飽和温度（Ｔ1）は、９５℃であった。Example 6 A 75% nitric acid aqueous solution prepared by operating in the same manner as in Example 1 [containing 75 g of nitric acid and 0.23 g of nitrous acid in 100 g]
contains. ] After adding 14.9 g of ion-exchanged water to 238.8 g, cerium (IV) oxide hydrate (including water of 21.5% by mass in addition to water of crystallization and impurities of 0.5% or less) 54.2 g was added, the temperature was raised to 100 ° C. with stirring, and the temperature was maintained at the same temperature for 1 hour with stirring to completely dissolve the cerium (IV) hydrate. Thereafter, the mixture was cooled to room temperature and filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate was heated to 98 ° C,
An aqueous solution of ammonium nitrate (an aqueous solution in which 49.1 g of ammonium nitrate (purity: 99.8%) was dissolved in 32.6 g of ion-exchanged water) was added dropwise while maintaining the temperature range of 98 ° C. to obtain an aqueous solution of cerium ammonium nitrate. The saturation temperature (T 1 ) of this aqueous solution was 95 ° C.
【００５０】その後、上記で得た硝酸セリウム(IV)アン
モニウムの水溶液を９０℃に冷却したところ、透明で懸
濁していなかった。冷却後の硝酸セリウム(IV)アンモニ
ウムの水溶液を９０℃に維持したまま、種晶（硝酸セリ
ウム(IV)アンモニウムの結晶、粒子径は１００μｍ〜１
０００μｍ）０．１ｇを加えところ、析出物は観察でき
なかった。その後、直ちに３．５時間かけて２０℃まで
冷却した。ここで９０℃から２０℃までの冷却に要した
時間は３．５時間であり、平均冷却速度は２０℃／時間
である。Thereafter, when the aqueous solution of cerium (IV) ammonium nitrate obtained above was cooled to 90 ° C., it was clear and not suspended. While maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C., a seed crystal (crystal of cerium (IV) ammonium nitrate, particle diameter of 100 μm to 1 μm) was used.
When 0.1 g of 000 μm) was added, no precipitate was observed. Then, it was immediately cooled to 20 ° C. over 3.5 hours. Here, the time required for cooling from 90 ° C. to 20 ° C. is 3.5 hours, and the average cooling rate is 20 ° C./hour.
【００５１】その後、２０℃で１時間保温し、フィルタ
ーを用いて濾過して、硝酸セリウム(IV)アンモニウムの
結晶（１２０．６ｇ）を得た。実施例１と同様にして求
めた硝酸セリウム(IV)アンモニウムの結晶の乾燥減量は
３．２％であり、乾燥後の純度は９９．５％であった。
この結晶の粒子径分布の評価結果を表１に示す。Thereafter, the mixture was kept at 20 ° C. for 1 hour and filtered with a filter to obtain cerium (IV) ammonium nitrate crystals (120.6 g). The loss on drying of the crystals of cerium (IV) ammonium nitrate determined in the same manner as in Example 1 was 3.2%, and the purity after drying was 99.5%.
Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００５２】実施例７ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中硝酸を７５ｇ含有し、亜硝酸を０．２８ｇ
含有する。〕２３８．８ｇにイオン交換水１４．９ｇを
加えたのち、酸化セリウム(IV)水和物（結晶水以外に質
量分率で２１．５％の水を含み、不純物は０．５％以
下）５４．２ｇを加え、攪拌しながら１００℃まで昇温
して、攪拌しながら同温度で１時間保温して酸化セリウ
ム(IV)水和物を完全に溶解させた。その後、室温まで冷
却し、目開き０．２μｍのメンブランフィルターで濾過
して濾液を得た。この濾液を９８℃に昇温し、９５℃〜
９８℃の温度範囲を維持しながら硝酸アンモニウム水溶
液〔硝酸アンモニウム（純度９９．８％）４８．９ｇを
イオン交換水３２．６ｇに溶解した水溶液〕を滴下して
加えて硝酸セリウムアンモニウムの水溶液を得た。この
水溶液の飽和温度（Ｔ1）は９５℃であった。Example 7 A 75% aqueous nitric acid solution prepared by operating in the same manner as in Example 1 [containing 75 g of nitric acid and 0.28 g of nitrous acid in 100 g]
contains. ] After adding 14.9 g of ion-exchanged water to 238.8 g, cerium (IV) oxide hydrate (including water of 21.5% by mass in addition to water of crystallization and impurities of 0.5% or less) 54.2 g was added, the temperature was raised to 100 ° C. with stirring, and the temperature was maintained at the same temperature for 1 hour with stirring to completely dissolve the cerium (IV) hydrate. Thereafter, the mixture was cooled to room temperature and filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate was heated to 98 ° C,
An aqueous solution of ammonium nitrate (an aqueous solution in which 48.9 g of ammonium nitrate (purity: 99.8%) was dissolved in 32.6 g of ion-exchanged water) was added dropwise while maintaining the temperature range of 98 ° C. to obtain an aqueous solution of cerium ammonium nitrate. The saturation temperature (T 1 ) of this aqueous solution was 95 ° C.
【００５３】その後、上記で得た硝酸セリウム(IV)アン
モニウムの水溶液を９０℃に冷却したところ、透明で懸
濁していなかった。冷却後の硝酸セリウム(IV)アンモニ
ウムの水溶液を９０℃に維持したまま、種晶（硝酸セリ
ウム(IV)アンモニウムの結晶、粒子径は１００μｍ〜１
０００μｍ）０．１ｇを加えところ、析出物は観察でき
なかった。その後、直ちに０．５時間かけて８０℃まで
冷却し、同温度を１時間保った後、３時間かけて２０℃
まで冷却した。ここで９０℃から２０℃までの冷却に要
した時間は合計３．５時間であり、平均冷却速度は２０
℃／時間である。Thereafter, when the aqueous solution of cerium (IV) ammonium nitrate obtained above was cooled to 90 ° C., it was clear and not suspended. While maintaining the cooled aqueous solution of cerium (IV) ammonium nitrate at 90 ° C., seed crystals (crystals of cerium (IV) ammonium nitrate, having a particle size of 100 μm to 1 μm)
000 μm), and no precipitate was observed. Then, immediately cool to 80 ° C. over 0.5 hour, maintain the same temperature for 1 hour, and then 20 ° C. for 3 hours.
Cooled down. Here, the time required for cooling from 90 ° C. to 20 ° C. was 3.5 hours in total, and the average cooling rate was 20 hours.
° C / hour.
【００５４】その後、２０℃で１時間保温し、フィルタ
ーを用いて濾過して、硝酸セリウム(IV)アンモニウムの
結晶（１２０．６ｇ）を得た。実施例１と同様にして求
めた硝酸セリウム(IV)アンモニウムの結晶の乾燥減量は
３．９％であり、乾燥後の純度は９８．９％であった。
この結晶の粒子径分布の評価結果を表１に示す。Thereafter, the mixture was kept at 20 ° C. for 1 hour and filtered with a filter to obtain cerium (IV) ammonium nitrate crystals (120.6 g). The loss on drying of the cerium (IV) ammonium nitrate crystals determined in the same manner as in Example 1 was 3.9%, and the purity after drying was 98.9%.
Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００５５】比較例１ 実施例１と同様に操作して調整した９８％硝酸水溶液
〔１００ｇ中硝酸を９８ｇ含有し、亜硝酸を０．２５ｇ
含有する。〕１６０．３ｇにイオン交換水５４．１ｇを
加えたのち、酸化セリウム(IV)水和物（結晶水以外に質
量分率で２３．４％の水を含み、不純物は０．５％以
下）６５．８ｇを加え、攪拌しながら１００℃まで昇温
して、攪拌しながら同温度で１時間保温して酸化セリウ
ム(IV)水和物を完全に溶解させた。その後、室温まで冷
却し、目開き０．２μｍのメンブランフィルターで濾過
して濾液を得た。この濾液を７５℃に昇温し、同温度を
維持しながら硝酸アンモニウム（純度９９．８％）６
２．８ｇの粉末を１時間かけて加えて、硝酸セリウム(I
V)アンモニウムの水溶液を得た。この水溶液は、硝酸セ
リウム(IV)アンモニウムの結晶が析出し、懸濁してい
た。この硝酸セリウム(IV)アンモニウムの水溶液の飽和
温度（Ｔ1）は９５℃であった。Comparative Example 1 A 98% aqueous nitric acid solution prepared by operating in the same manner as in Example 1 [containing 98 g of nitric acid and 0.25 g of nitrous acid in 100 g]
contains. After adding 54.1 g of ion-exchanged water to 160.3 g, cerium (IV) oxide hydrate (including water of 23.4% by mass fraction in addition to water of crystallization, and impurities of 0.5% or less) 65.8 g was added, the temperature was raised to 100 ° C. with stirring, and the temperature was maintained at the same temperature with stirring for 1 hour to completely dissolve the cerium (IV) oxide hydrate. Thereafter, the mixture was cooled to room temperature and filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate was heated to 75 ° C., and while maintaining the same temperature, ammonium nitrate (purity 99.8%) 6
2.8 g of powder was added over 1 hour and cerium nitrate (I
V) An aqueous solution of ammonium was obtained. In this aqueous solution, crystals of cerium (IV) ammonium nitrate precipitated and were suspended. The saturation temperature (T 1 ) of the aqueous solution of cerium (IV) ammonium nitrate was 95 ° C.
【００５６】上記で得た硝酸セリウム(IV)アンモニウム
の水溶液を７５℃に維持したまま、種晶（硝酸セリウム
(IV)アンモニウムの結晶、粒子径は１００μｍ〜１００
０μｍ）０．１ｇを加え、直ちに５．５時間かけて同じ
冷却速度で２０℃まで冷却した。ここで７５℃から２０
℃までの冷却に要した時間は５．５時間であり、平均冷
却速度は１０℃／時間である。While maintaining the aqueous solution of cerium (IV) ammonium nitrate obtained above at 75 ° C., a seed crystal (cerium (IV) nitrate) was obtained.
(IV) Ammonium crystal, particle diameter is 100 μm to 100
(0 μm) and immediately cooled to 20 ° C. at the same cooling rate over 5.5 hours. Here from 75 ° C to 20
The time required for cooling to ° C. was 5.5 hours, and the average cooling rate was 10 ° C./hour.
【００５７】その後、直ちにフィルターを用いて濾過し
て、硝酸セリウム(IV)アンモニウムの結晶（１６９．２
ｇ）を得た。実施例１と同様にして求めた硝酸セリウム
(IV)アンモニウムの結晶の乾燥減量は６．７％であり、
乾燥後の純度は９５．６％であった。この結晶の粒子径
分布の評価結果を表１に示す。Thereafter, the mixture was immediately filtered using a filter, and crystals of cerium (IV) ammonium nitrate (169.2) were obtained.
g) was obtained. Cerium nitrate obtained in the same manner as in Example 1.
(IV) the loss on drying of the ammonium crystals is 6.7%;
The purity after drying was 95.6%. Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００５８】比較例２ 実施例１と同様に操作して調整した７５％硝酸水溶液
〔１００ｇ中硝酸を７５ｇ含有し、亜硝酸を０．２０ｇ
含有する。〕２３８．８ｇにイオン交換水１４．９ｇを
加えたのち、酸化セリウム(IV)水和物（結晶水以外に質
量分率で２１．５の水を含み、不純物は０．５％以下）
５４．２ｇを加え、攪拌しながら１００℃まで昇温し
て、攪拌しながら同温度で１時間保温して酸化セリウム
(IV)水和物を完全に溶解させた。その後、室温まで冷却
し、目開き０．２μｍのメンブランフィルターで濾過し
て濾液を得た。この濾液を８０℃に昇温し、同温度を維
持しながら硝酸アンモニウム水溶液〔硝酸アンモニウム
（純度９９．８％）４９．６ｇをイオン交換水３３．０
ｇに溶解した水溶液〕を３０分かけて滴下して加えて、
硝酸セリウム(IV)アンモニウムの水溶液を得た。この水
溶液は、懸濁していなかった。この硝酸セリウム(IV)ア
ンモニウムの水溶液の飽和温度（Ｔ1）を実施例１と同
様にして評価したところ、９５℃であった。Comparative Example 2 A 75% aqueous nitric acid solution prepared and operated in the same manner as in Example 1 [containing 75 g of nitric acid and 0.20 g of nitrous acid in 100 g]
contains. ] After adding 14.9 g of ion-exchanged water to 238.8 g, cerium (IV) oxide hydrate (including water of 21.5 by mass fraction besides crystallization water, impurities are 0.5% or less)
54.2 g was added, the temperature was increased to 100 ° C. with stirring, and the temperature was maintained at the same temperature for 1 hour with stirring to obtain cerium oxide.
(IV) The hydrate was completely dissolved. Thereafter, the mixture was cooled to room temperature and filtered through a membrane filter having an aperture of 0.2 μm to obtain a filtrate. The filtrate was heated to 80 ° C., and while maintaining the same temperature, 49.6 g of an ammonium nitrate aqueous solution [ammonium nitrate (purity: 99.8%) was ion-exchanged with 33.0 g of water.
aqueous solution dissolved in g) over 30 minutes.
An aqueous solution of cerium (IV) ammonium nitrate was obtained. This aqueous solution was not suspended. When the saturation temperature (T 1 ) of the aqueous solution of cerium (IV) ammonium nitrate was evaluated in the same manner as in Example 1, it was 95 ° C.
【００５９】上記で得た硝酸セリウム(IV)アンモニウム
の水溶液を８０℃に維持したまま、種晶（硝酸セリウム
(IV)アンモニウムの結晶、粒子径は１００μｍ〜１００
０μｍ）０．１ｇを加えたところ、硝酸セリウム(IV)ア
ンモニウムの結晶が析出して、懸濁した。その後、直ち
に６時間かけて同じ冷却速度で２０℃まで冷却した。こ
こで８０℃から２０℃までの冷却に要した時間は８時間
であり、平均冷却速度は１０℃／時間である。While maintaining the aqueous solution of cerium (IV) ammonium nitrate obtained above at 80 ° C.,
(IV) Ammonium crystal, particle diameter is 100 μm to 100
(0 μm) and 0.1 g of cerium (IV) ammonium nitrate was precipitated and suspended. Thereafter, the mixture was immediately cooled to 20 ° C. at the same cooling rate over 6 hours. Here, the time required for cooling from 80 ° C. to 20 ° C. is 8 hours, and the average cooling rate is 10 ° C./hour.
【００６０】その後、直ちにフィルターを用いて濾過し
て、硝酸セリウム(IV)アンモニウムの結晶（１２４．９
ｇ）を得た。実施例１と同様にして硝酸セリウム(IV)ア
ンモニウムの結晶の乾燥減量は５．２％であり、乾燥後
の純度は９９．２％であった。この結晶の粒子径分布の
評価結果を表１に示す。Thereafter, the mixture was immediately filtered using a filter, and crystals of cerium (IV) ammonium nitrate (124.9) were obtained.
g) was obtained. As in Example 1, the loss on drying of the cerium (IV) ammonium nitrate crystals was 5.2%, and the purity after drying was 99.2%. Table 1 shows the evaluation results of the particle size distribution of the crystals.
【００６１】比較例３ 種晶を加えたのち、直ちに冷却を開始して、２０℃まで
２時間をかけて一定の速度で冷却する以外は、実施例１
と同様に操作して得られる硝酸セリウム(IV)アンモニウ
ムの結晶は、粒子径の小さい結晶の割合が小さい。Comparative Example 3 Example 1 was repeated except that cooling was started immediately after the seed crystal was added and then cooled to a constant rate over 20 hours to 20 ° C.
In the cerium (IV) ammonium nitrate crystals obtained by the same operation as described above, the proportion of crystals having a small particle diameter is small.
【００６２】[0062]
【表１】 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 粒子径 75μm 106μm 150μm 212μm 300μm 500μm 710μm 以下 以下 以下 以下 以下 以下 以下 ───────────────────────────────── 実施例１ 0.00 0.00 0.23 1.15 5.76 36.51 77.56 実施例２ 0.00 0.00 0.15 0.75 4.29 29.95 71.03 実施例３ 0.00 0.29 0.58 2.30 7.09 42.54 86.79 実施例４ 0.00 1.21 3.48 6.13 9.46 19.67 61.20 実施例５ 0.00 0.15 0.76 2.66 9.81 53.08 89.05 実施例６ 0.00 0.08 0.46 1.60 4.79 19.45 60.18 実施例７ 0.00 0.23 0.54 1.69 5.38 19.06 59.88 ───────────────────────────────── 比較例１ 0.00 1.50 4.92 23.32 65.11 95.00 98.35 比較例２ 0.00 0.69 2.58 7.50 26.60 78.43 96.97 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 単位は（％）[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Particle size 75μm 106μm 150μm 212μm 300μm 500μm 710μm or less or less以下 Example 1 0.00 0.00 0.23 1.15 5.76 36.51 77.56 Example 2 0.00 0.00 0.15 0.75 4.29 29.95 71.03 Example 3 0.00 0.29 0.58 2.30 7.09 42.54 86.79 Example 4 0.00 1.21 3.48 6.13 9.46 19.67 61.20 Example 5 0.00 0.15 0.76 2.66 9.81 53.08 89.05 Example 6 0.00 0.08 0.46 1.60 4.79 19.45 60.18 Example 7 0.00 0.23 0.54 1.69 5.38 19.06 59.88 ───────────────────────────────── Comparative Example 1 0.00 1.50 4.92 23.32 65.11 95.00 98.35 Comparative Example 2 0.00 0.69 2.58 7.50 26.60 78.43 96.97 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Unit is (%)
Claims (5)
に、硝酸セリウム(IV)アンモニウムの飽和温度（Ｔ1）
以下（Ｔ1−１０℃）以上の温度で種晶を加えた後、該
水溶液を平均冷却速度２５℃／時間以下で３０℃以下ま
で冷却して、硝酸セリウム(IV)アンモニウムの結晶を析
出させることを特徴とする硝酸セリウム(IV)アンモニウ
ムの製造方法。1. An aqueous solution of cerium (IV) ammonium nitrate is added to an aqueous solution of cerium (IV) ammonium nitrate at a saturation temperature (T 1 ).
After adding a seed crystal at a temperature equal to or higher than (T 1 -10 ° C.), the aqueous solution is cooled to 30 ° C. or lower at an average cooling rate of 25 ° C./hour or lower to precipitate cerium (IV) ammonium nitrate crystals. A method for producing cerium (IV) ammonium nitrate, comprising:
を、酸化セリウム(IV)水和物または水酸化セリウム(IV)
を硝酸水溶液に溶解させたのち硝酸アンモニウムと混合
して得る請求項１に記載の製造方法。2. An aqueous solution of cerium (IV) ammonium nitrate is added to cerium (IV) oxide hydrate or cerium (IV) hydroxide.
2. The method according to claim 1, wherein the compound is dissolved in an aqueous nitric acid solution and then mixed with ammonium nitrate.
水溶液を用いる請求項２に記載の製造方法。3. The method according to claim 2, wherein an aqueous solution of ammonium nitrate is used as ammonium nitrate.
和物または水酸化セリウム(IV)１モルあたり４モル以上
２０モル以下となるように使用する請求項２または請求
項３に記載の製造方法。4. The method according to claim 2, wherein the nitric acid aqueous solution is used so that the amount of nitric acid is from 4 mol to 20 mol per 1 mol of cerium (IV) oxide hydrate or cerium (IV) hydroxide. Manufacturing method.
±５℃の温度範囲に３０分以上保持し、次いで３０℃以
下に冷却する請求項１に記載の製造方法。5. The method according to claim 1, wherein after the seed crystal is added, the temperature is kept in a temperature range of 50 ° C. to 90 ° C. and ± 5 ° C. for 30 minutes or more, and then cooled to 30 ° C. or less.
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| CN114560499A (en) * | 2022-03-31 | 2022-05-31 | 广东先导稀材股份有限公司 | Production method of pentahydrate bismuth nitrate |
| CN114604886A (en) * | 2018-01-15 | 2022-06-10 | 赣州湛海新材料科技有限公司 | Method for preparing large-particle rare earth oxide |
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