JP6169120B2 - Cerium-containing solution and method for producing the same - Google Patents

Description

  The present invention relates to a solution containing tetravalent cerium that can be used in producing various organic / inorganic compounds and a method for producing the same.

  Rare earth elements are generic names for scandium (Sc), yttrium (Y) and lanthanoid elements belonging to Group 3 of the long-period periodic table, and cerium (Ce) is also known as a rare earth element. This cerium is an element belonging to the lanthanoid element, in addition to cerium, lanthanum (La), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium ( Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), and the like also belong to the lanthanoid elements.

  One of the characteristics of rare earth elements is that their chemical properties are similar to each other. Among the elements belonging to the rare earth elements, elements other than scandium having slightly different properties coexist in the same ore such as ion adsorbed ore. And as mentioned above, since these elements have similar chemical properties, it is very difficult to separate each element as a simple substance, and it is often used in a mixture state.

  Cerium is a heterogeneous rare earth element and has trivalent and tetravalent valences in aqueous solution. It is known that the reduction potential for the reduction reaction from tetravalent cerium to trivalent cerium in an aqueous solution is as large as about 1.6 to 1.7 V. For this reason, tetravalent cerium aqueous solutions are used as a powerful oxidizing reagent in various fields including organic synthesis. In recent years, tetravalent cerium aqueous solutions have been frequently used as powerful oxidants for activating metal catalysts in research on catalytic reactions that generate hydrogen and oxygen gas from water molecules. Thus, tetravalent cerium aqueous solution is a useful raw material in many fields, and its utility value is very high.

  Known solutions containing tetravalent cerium include a tetravalent cerium sulfate aqueous solution and a nitrate aqueous solution. In these aqueous solutions, in order to stably maintain the tetravalent state, it is necessary to maintain the pH of the aqueous solution at 4 or less, preferably 2 or less. As a simple method for maintaining the pH within a predetermined range, it is known that an appropriate amount of excess nitric acid or sulfuric acid is present in the aqueous solution. If the pH of the aqueous solution is higher than 4 and moves closer to the basic side, solids such as cerium hydroxide are likely to precipitate, so care must be taken when handling a tetravalent cerium salt aqueous solution at pH 4 or higher on an industrial scale. It is. Further, in preparing a solution containing cerium ions, a predetermined amount of a diluted solution of cerium salt is added to another raw material solution to prepare a solution containing cerium ions. However, when a solution containing cerium ions in the acidic region is diluted with water, the pH approaches the basic side, which may cause cerium hydroxide and the like to precipitate, and a uniform solution cannot be obtained. . In particular, when heating a solution containing cerium ions, the precipitation is accelerated, so care must be taken.

  Various solutions containing cerium ions and their production methods have been proposed so far. For example, in Patent Document 1, by adding ammonia water to an aqueous solution containing a tetravalent cerium compound, the solution is adjusted to neutral or alkaline, and the solid content obtained by heat treatment is dispersed in water. The preparation of a cerium oxide abrasive is disclosed. In this manufacturing method, a cerium salt such as cerium sulfate, ammonium cerium sulfate, or ammonium cerium nitrate is used as the tetravalent cerium compound, and a solution containing tetravalent cerium ions is prepared by dissolving them.

  In Patent Document 2, basic cerium carbonate is produced by adding and reacting an aqueous urea solution while stirring a 0.05 to 0.2 mol / L trivalent cerium salt aqueous solution at a predetermined temperature. It is disclosed.

  Furthermore, Patent Document 3 discloses a method for producing a trivalent cerium salt by a step of reacting a cerium (III) compound with a reducing organic acid having three or more coordination sites. In Patent Document 3, when an aqueous solution having trivalent cerium ions such as cerium (III) acetate is prepared, trivalent cerium ions are oxidized into tetravalent cerium ions within a relatively short time. Is disclosed.

  Patent Document 4 discloses a trivalent cerium ion-containing solution containing trivalent cerium ions and a non-organic acid substance having a reducing action in an acidic region.

JP-A-9-270402 JP 2000-159521 A JP 2004-307343 A JP 2006-327839 A

  As described above, although cerium solutions containing cerium ions and methods for producing the same have been actively developed, no technology has been developed that allows a tetravalent cerium solution to exist stably in a weakly alkaline or alkaline region. . Although various cerium ion-containing solutions having excellent stability have been proposed as in the above-mentioned patent documents, white precipitation of cerium oxide particles occurs when the aqueous solution is made alkaline. As disclosed in Patent Document 3, tetravalent cerium ions easily react with water and change into cerium (IV) hydroxide or cerium (IV) oxide to be insolubilized in an aqueous solution. Because.

  In addition, since tetravalent cerium solutions are conventionally unstable in the alkaline region, when using them as raw materials or storing them for a long period of time, it is necessary to pay sufficient attention to the management of pH and the like. was there. As described above, since the tetravalent cerium solution has poor stability in the alkaline region, its concentration cannot be increased, and has not reached a concentration that can be used industrially. As described above, tetravalent cerium solutions have high utility value in various fields, but no tetravalent cerium solution that can maintain a stable solution state in an alkaline region at a concentration that can be used industrially has been developed. Is the current situation.

  The present invention has been made in view of the above, a tetravalent cerium-containing solution that can maintain a stable solution state even in an alkaline region, and that does not easily generate precipitates even at a high concentration, and its An object is to provide a manufacturing method.

  As a result of intensive studies to achieve the above object, the present inventor has found that the above object can be achieved by allowing an oxidant to coexist in a cerium-containing solution, and the present invention has been completed.

That is, this invention relates to the following cerium containing solution and its manufacturing method.
1. Carbonate ion, a monovalent cation, only containing tetravalent cerium ions and oxidizing agent, the cerium-containing solution, wherein the pH of 7 or more.
2. The cerium-containing solution according to item 1, wherein the monovalent cation contains an ammonium ion.
3. Item 3. The cerium-containing solution according to item 1 or 2 , wherein the tetravalent cerium ion is contained in an amount of 0.5% by weight or more in terms of oxide.
4). Any one of the above items 1 to 3 , wherein the oxidizing agent is at least one selected from the group of oxidizing compounds containing hydrogen peroxide, inorganic peroxides, persalts and halogen atoms. The cerium-containing solution according to item.
5. 5. The cerium-containing solution according to item 4 , wherein the oxidizing agent is at least one compound or two or more compounds from the group of hydrogen peroxide, sodium peroxoborate and sodium peroxocarbonate.
6). The following steps (1) to (5):
(1) a first step of preparing a raw material solution containing at least one of an ammonium ion-containing alkaline aqueous solution and water and a cerium compound;
(2) a second step of preparing a mixed solution by mixing the raw material liquid prepared in the first step and at least one of carbonate and bicarbonate.
(3) Third step of stirring the mixed solution prepared in the second step at 10 to 50 ° C. for 10 to 60 minutes,
(4) a fourth step of blending an oxidizing agent into the mixed liquid heated in the third step,
(5) A fifth step of obtaining a cerium-containing solution by aging the solution prepared in the fourth step at 30 to 50 ° C. for 30 minutes to 15 hours,
The method for producing a cerium-containing solution according to any one of items 1 to 5 , wherein the cerium-containing solution is provided.

  According to the cerium-containing solution of the present invention, precipitates are hardly generated even in a weak alkaline or alkaline region, and a stable solution state can be maintained. Further, according to the cerium-containing solution of the present invention, even if the concentration of cerium ions in the cerium-containing solution is high, precipitates are hardly generated and a homogeneous solution state can be maintained. Therefore, in the past, when a tetravalent cerium solution was used, the solution had to be adjusted to an acidic or neutral region, whereas in the cerium-containing solution of the present invention, pH adjustment was performed to maintain solution stability. Is unnecessary, and industrial versatility is greatly expanded.

  In addition, according to the method for producing a cerium-containing solution according to the present invention, a cerium-containing solution that is excellent in stability of a solution even in a weakly alkaline or alkaline region and that does not easily generate precipitates even at a high concentration is easily produced. be able to.

It is a general | schematic flow sheet for demonstrating an example of the process of manufacturing the cerium containing solution of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, “%” means “% by weight (or mass%)” unless otherwise specified.

1. Cerium-containing solution The cerium-containing solution of the present invention contains carbonate ions, monovalent cations, tetravalent cerium ions and an oxidizing agent. Such a cerium-containing solution containing each component is less likely to form precipitates such as cerium (IV) hydroxide and cerium (IV) oxide even in a weakly alkaline or alkaline region, and maintains a stable solution state. be able to. Moreover, even if the concentration of the cerium-containing solution is high, the above precipitates are not easily generated, and a homogeneous solution state can be maintained.

  The solvent of the cerium-containing solution is not limited, and water and ethanol are generally used industrially. However, other alcohols and organic solvents may be used, or water and other solvents may be mixed. Good.

  As a raw material for introducing carbonate ions into a cerium-containing solution, a compound that dissolves in a solvent and is ionized into carbonate ions or an aqueous solution thereof is usually mentioned. Examples of such a raw material serving as a carbonate ion source include carbonates and bicarbonates. Specifically, ammonium carbonate, ammonium bicarbonate (ammonium bicarbonate), sodium carbonate, sodium bicarbonate, potassium carbonate. And one or more selected from the group consisting of cesium carbonate and aqueous solutions thereof.

The monovalent cation is not particularly limited, but ammonium ion (NH ₄ ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), lithium ion (Li ⁺ ), silver ion (Ag ⁺ ), copper (I) Examples include, but are not limited to, ions (Cu ⁺ ), rubidium ions (Rb ⁺ ), cesium ions (Cs ⁺ ), and the like. Among these, ammonium ion, sodium ion, potassium ion, rubidium ion, and cesium ion are preferable.

  The monovalent cation contained in the cerium-containing solution may be only one kind or two or more kinds. When two or more kinds of monovalent cations are contained in the cerium-containing solution, the combination is not particularly limited, and examples thereof include a combination of sodium ion and ammonium ion.

  As a raw material for introducing a monovalent cation into a cerium-containing solution, a compound that dissolves in a solvent and ionizes to a monovalent cation or an aqueous solution thereof is usually mentioned. Examples of such a raw material that becomes a monovalent cation source include the carbonates and bicarbonates described above, and the group consisting of chlorides, perchlorates, sulfates, nitrates, and aqueous solutions thereof. 1 type or 2 types or more selected from more are illustrated.

For example, if the monovalent cation is ammonium ion (NH ₄ ⁺ ), one kind selected from the group consisting of ammonium chloride, ammonium perchlorate, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonia, and aqueous solutions thereof, or the like Two or more types are exemplified.

  Examples of raw materials for introducing tetravalent cerium ions into a cerium-containing solution include various cerium compounds or aqueous solutions of these cerium compounds. Examples of the cerium compound include one or more selected from the group consisting of cerium carbonate, cerium sulfate, ammonium cerium sulfate, cerium nitrate, and the like.

  As the oxidizing agent, those commercially available for reagents and industrial use can be used. Examples of preferable oxidizing agents include at least one or two or more selected from the group of oxidizing compounds containing hydrogen peroxide, inorganic peroxides, persalts and halogen atoms.

  Examples of the inorganic peroxide include lithium peroxide, sodium peroxide, barium peroxide, calcium peroxide, and zirconium peroxide. Examples of the peracid salt include peroxyborate, persulfate, percarbonate, perphosphate, hypoperchlorate, peracetate, and the like. Examples of the oxidizing compound containing a halogen atom include compounds such as hypohalite, halite, and halogenate, and particularly sodium hypochlorite and sodium nitrite. The above-mentioned oxidizers may be used in a solid state such as powder or granule, or in a solution state dissolved in a solvent such as water.

  More preferred oxidizing agents include one or more selected from the group consisting of hydrogen peroxide, sodium peroxoborate and sodium peroxocarbonate. When such an oxidizing agent is contained in the cerium-containing solution, it is easier to prevent the occurrence of precipitates in the cerium-containing solution.

  The cerium-containing solution can be adjusted to a wide pH range at room temperature. In particular, the pH of the cerium-containing solution is preferably 7 or more at room temperature, and the cerium-containing solution exists stably in such a pH range. That is, even if the cerium-containing solution is stored for a long period of time, precipitates are hardly generated in the cerium-containing solution, and a uniform solution state is maintained. The pH of the cerium-containing solution at room temperature is particularly preferably 8 or higher.

  The tetravalent cerium ions contained in the cerium-containing solution are preferably 0.5% by weight or more based on the total amount of the cerium-containing solution in terms of oxides. Oxide conversion here is cerium oxide conversion. If the tetravalent cerium ions are contained in the above amount, the solution contains a sufficient amount of tetravalent cerium ions. Even if the cerium-containing solution is used as a raw material for the synthesis of organic compounds, the The function can be fully exhibited. In particular, the tetravalent cerium ions contained in the cerium-containing solution are more preferably 1.0% by weight or more, and more preferably 3.0% by weight or more, in terms of oxide, with respect to the total amount of the cerium-containing solution. The upper limit of the content of tetravalent cerium ions contained in the cerium-containing solution is not particularly limited, and is saturated at 12% by weight in terms of oxides. However, oxidation is performed from the viewpoint of maintaining the stability of the cerium-containing solution. It is preferably 5% by weight in terms of product.

  As described above, the cerium-containing solution contains at least a monovalent cation, a carbonate ion, and an oxidizing agent. By the action of the oxidizing agent, trivalent cerium ions such as cerium carbonate become tetravalent. And this tetravalent cerium ion, ammonium ion, and carbonate ion are stabilized by forming a complex, and the chemical change of cerium ion to cerium hydroxide (IV) or cerium oxide (IV) is suppressed. it is conceivable that. Therefore, in the case of a conventional cerium-containing solution, cerium (IV) hydroxide or cerium oxide (IV) or the like is precipitated as a precipitate in the solution due to the above chemical change, whereas in the cerium-containing solution of the present invention, , The chemical change is suppressed, so that the precipitate is not easily generated. In particular, it is difficult for precipitates to occur even in weakly alkaline or alkaline regions where it has been difficult to prevent the generation of precipitates.

  Therefore, when the cerium-containing solution is stored for a long period of time, or when this solution is heated or diluted, the cerium-containing solution is brought into a uniform state without adjusting the pH to the acidic range as in the prior art. Can be maintained. Further, since the stability of the cerium-containing solution is high, the precipitates are not easily generated in the solution even if the concentration of tetravalent cerium ions is high. Therefore, it is also possible to prepare a high concentration tetravalent cerium ion-containing solution, and the industrial versatility is greatly expanded.

  The cerium-containing solution of the present invention can be used in various organic syntheses as a powerful oxidizing reagent, and is used as a raw material for producing cerium oxide and cerium-containing composite oxides (for example, promoters and abrasives for exhaust gas purification automobile catalysts) Etc.), cerium sol and cerium-containing sol production raw materials, cerium-containing inorganic and organic compound production raw materials, and other oxidizing agents.

  The cerium-containing solution may contain other additives as long as the above effects are not hindered.

2. Manufacturing method of cerium containing solution The said cerium containing solution can be manufactured by passing through the process which has the 1st process-the 5th process as described in the following (1)-(5).
(1) a first step of preparing a raw material solution containing at least one of an ammonium ion-containing alkaline aqueous solution and water and a cerium compound;
(2) a second step of preparing a mixed solution by mixing the raw material liquid prepared in the first step and at least one of carbonate and bicarbonate.
(3) Third step of stirring the mixed solution prepared in the second step at 10 to 50 ° C. for 10 to 60 minutes,
(4) a fourth step of blending an oxidizing agent into the mixed liquid heated in the third step,
(5) A fifth step of obtaining a cerium-containing solution by aging the solution prepared in the fourth step at 30 to 50 ° C. for 30 minutes to 15 hours.

  FIG. 1 shows a schematic flow sheet for explaining an example of a process for producing a cerium-containing solution.

  In the first step, a raw material solution containing at least one of an ammonium ion-containing alkaline aqueous solution and water (hereinafter abbreviated as “medium”) and a cerium compound is prepared.

  Although it does not restrict | limit especially as said ammonium ion containing alkaline aqueous solution, For example, ammonia water, ammonium carbonate aqueous solution, ammonium hydrogencarbonate aqueous solution etc. are illustrated, These can use 1 type or 2 types or more together. The concentration of the ammonium ion-containing alkaline aqueous solution is not particularly limited, but can be, for example, 10 to 30%.

  As the water, pure water, ion exchange water, distilled water, various purified water, and the like can be used.

  When an ammonium ion-containing alkaline aqueous solution is used in the first step, the monovalent cation contained in the resulting cerium-containing solution contains ammonium ions.

  As said cerium compound, the compound similar to the various cerium compounds used as the tetravalent cerium ion source mentioned above can be used.

  In blending the medium and the cerium compound in the first step, for example, the cerium compound can be added while stirring the medium. There are no particular limitations on the stirrer, stirring speed, etc. for stirring the medium.

  In the raw material liquid obtained in the first step, the cerium compound is dispersed in the medium. In this raw material liquid, the solid content concentration of the cerium compound is preferably 5 to 50%, more preferably 15 to 40%, and more preferably 20 to 35% with respect to the total amount of the medium and the cerium compound. It is particularly preferred. If the solid content concentration of the raw material liquid is 15% or more, it is easy to prevent a decrease in the efficiency of obtaining a cerium solution. Moreover, if the solid content concentration of the raw material liquid is 40% or less, it is difficult to stir and it is easy to prepare a uniform dispersion.

  In the second step, the raw material solution prepared in the first step is mixed with at least one of carbonate and bicarbonate (hereinafter abbreviated as “carbonate ion-containing alkali compound”) to prepare a mixed solution.

  The carbonate ion-containing alkali compound is preferably one or more selected from the group consisting of ammonium carbonate, ammonium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, rubidium carbonate, cesium carbonate and the like. These compounds may be used in a solid state or in an aqueous solution state.

  By using the carbonate ion-containing alkali compound, a monovalent cation can be introduced into the resulting cerium-containing solution. For example, if ammonium carbonate is used as the carbonate ion-containing alkali compound, the resulting cerium-containing solution contains ammonium ion as a monovalent cation, and if sodium hydrogen carbonate is used as the carbonate ion-containing alkali compound, the cerium-containing solution is generated. The solution contains sodium ions as monovalent cations.

  The carbonate ion-containing alkali compound can be added in a state where the raw material liquid obtained in the first step is stirred. The stirrer to be used, the number of stirring revolutions, etc. are not particularly limited. The temperature of the raw material liquid for adding the carbonate ion-containing alkali compound is preferably maintained at 10 to 40 ° C. If it is within this temperature range, it can move to the next third step quickly, and if the temperature of the raw material liquid does not exceed 40 ° C, the concentration change due to the release of carbon dioxide and ammonia to the outside and the decrease in the amount of water will occur. Since there is no fear, there is no possibility of adversely affecting the raw material liquid. The temperature is more preferably 25 to 35 ° C.

  The blending amount of the carbonate ion-containing alkali compound with respect to the raw material liquid is not particularly limited, but the carbonate ion-containing alkali compound can be 10 to 150 parts by weight with respect to 100 parts by weight of the raw material liquid obtained in the first step. May be 50 to 100 parts by weight.

  In the third step, the liquid mixture prepared in the second step is stirred at 10 to 50 ° C. for 10 to 60 minutes. By this stirring, the carbonate ion-containing alkali compound is uniformly dispersed in the mixed solution.

  When the heating temperature in the third step is less than 10 ° C., the carbonate ion-containing alkali compound is not sufficiently dispersed, and it becomes difficult to obtain a uniform mixture. When the heating temperature exceeds 50 ° C., the ions of the mixed solution prepared in the second step The concentration may change and the stability of the solution may decrease. In particular, the heating temperature is more preferably 20 ° C. to 40 ° C. In this case, it is easier to suppress the remaining precipitates and the concentration change of the solution. A particularly preferred heating temperature is 25 to 35 ° C.

  Moreover, when the time of the stirring treatment in the third step is less than 10 minutes, the mixed solution prepared in the second step and the carbonate ion-containing alkali compound are not mixed uniformly, and insoluble matters are precipitated in the subsequent steps. There is a case. If the stirring time exceeds 60 minutes, the cerium-containing solution having the desired physical properties may not be obtained, for example, the ionic concentration of the mixed solution changes due to evaporation of moisture or the like and the stability of the solution decreases. The stirring time is more preferably 15 to 40 minutes. In this case, precipitation of the precipitate and change in physical properties can be further suppressed. Particularly preferred stirring time is 15 to 20 minutes.

  In the fourth step, an oxidizing agent is added to the mixed liquid heated in the third step. By this step, a solution containing an oxidizing agent is prepared. By adding an oxidizing agent in the fourth step, trivalent cerium in cerium carbonate becomes tetravalent cerium. This tetravalent cerium is presumed to react with ammonium ions and carbonate ions to form another water-soluble substance (for example, a complex such as ammonium zirconium carbonate).

  Although it does not specifically limit as an oxidizing agent, As above-mentioned, it is at least 1 sort (s) or 2 or more types selected from the group of the oxidizing compound containing hydrogen peroxide, an inorganic peroxide, a peroxy acid salt, and a halogen atom It is preferable. The oxidizing agent can be added in the form of an aqueous solution such as hydrogen peroxide solution, for example.

  In blending the oxidizing agent, it is preferable to add the oxidizing agent while the solution is stirred. The stirrer used at this time, the rotation speed of stirring, and the like are not particularly limited. Moreover, when adding an oxidizing agent to a solution, it is preferable to heat a solution to 30-60 degreeC and hold | maintain in that state. If the solution is kept at 30 ° C. or higher, it is easy to suppress the formation of precipitates in the solution, and if it is kept at 60 ° C. or lower, the moisture of the solution is evaporated and the physical properties of the solution are prevented from changing. It becomes easy. The temperature of the solution is more preferably kept at 40 to 50 ° C.

  Although the compounding quantity of an oxidizing agent is not restrict | limited in particular, For example, an oxidizing agent can be 0.1-25 weight part with respect to 100 weight part of solutions obtained at the 3rd process.

  In the fifth step, the solution prepared in the fourth step is aged at 30 to 50 ° C. for 30 minutes to 15 hours. Through this step, a cerium-containing solution can be obtained.

  In the fifth step, when aging is performed at a solution temperature of less than 30 ° C., depending on the particle size of the cerium carbonate compound used, the reaction does not proceed sufficiently when an oxidizing agent is added, and an undissolved residue is formed. In addition, when aging is performed at a temperature exceeding 50 ° C, aging progresses excessively. As a result, the reaction product may be decomposed by the release of carbon dioxide or ammonia gas, which may change to cerium oxide or cerium hydroxide. A tetravalent cerium-containing solution cannot be obtained. The temperature of the solution during aging is more preferably 35 to 45 ° C. In this case, generation of precipitates and excessive aging can be further suppressed.

  In addition, in the fifth step, when the time for aging is less than 30 minutes, depending on the particle size of the cerium carbonate compound used, the reaction does not proceed sufficiently when an oxidizing agent is added, and an undissolved residue is formed. If the aging time is 15 hours or longer, moisture, ammonia components and carbon dioxide are released from the solution to the outside air, and a stable tetravalent cerium solution cannot be obtained. The time for aging is more preferably 30 minutes to 10 hours.

  As described above, the cerium-containing solution can be produced through the steps including the first step to the fifth step. According to such a manufacturing method, a cerium-containing solution can be easily manufactured. In addition, since it is possible to produce tetravalent cerium ions so that they do not precipitate in the solution, the yield of the cerium-containing solution is high and the production method is excellent in production efficiency. The cerium-containing solution produced by the method as described above is excellent in stability of the solution even in a weakly alkaline or alkaline region, and even if the concentration is high, precipitates are hardly generated. Therefore, the cerium-containing solution produced by the above method can be used as a powerful oxidizing reagent in various organic syntheses, and in particular, a raw material for producing cerium oxide and a cerium-containing composite oxide (for example, an exhaust gas purification automobile catalyst). And the like, and as a raw material for producing cerium sol and cerium-containing sol, a raw material for producing cerium-containing inorganic and organic compounds, and other oxidizing agents.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the aspect of these Examples.

Example 1
A cerium-containing solution was produced at the blending ratio shown in Table 1 below. First, 100 parts by weight of water and 100 parts by weight of 25% aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed to prepare an aqueous ammonium ion-containing alkaline solution. While stirring the alkaline aqueous solution, 100 parts by weight of trivalent cerium carbonate (Daiichi Rare Element Chemical Co., Ltd.) was added to prepare a raw material liquid in which cerium carbonate was dispersed in the alkaline aqueous solution.

  Next, while stirring the raw material liquid at 25 ° C., 150 parts by weight of ammonium bicarbonate (Nissan Chemical Industry Co., Ltd.), which is a carbonate ion-containing alkaline compound, is added to prepare a mixed liquid (second Step), and then stirring was continued for 20 minutes at 30 ° C. (third step).

  Next, while stirring the mixture prepared as described above, the mixture was heated until the temperature of the mixture reached 45 ° C., and kept at this temperature for 20 minutes. Thereafter, while maintaining the temperature of the mixed solution at 45 ° C., 50 parts by weight of 30% hydrogen peroxide water (manufactured by Wako Pure Chemical Industries, Ltd.) as an oxidizing agent was added, and stirring was continued (fourth step). .

  Next, the solution to which hydrogen peroxide solution has been added as described above is kept at 35 ° C. with stirring, and the solution is aged by being held at this temperature for 180 minutes (fifth step). Got.

(Example 2)
As in Example 1, except that the blending amounts of water, aqueous ammonia, cerium carbonate, ammonium bicarbonate and oxidizing agent were as shown in Table 1 below and stirring was continued for 40 minutes at 20 ° C. in the third step. A cerium-containing solution was obtained by the method described above.

(Examples 3 to 11, Comparative Example 1)
A cerium-containing solution was obtained in the same manner as in Example 1 except that the amounts of water, aqueous ammonia, cerium carbonate, ammonium bicarbonate, and oxidizing agent were as shown in Table 1 below. In Example 10, the oxidizing agent was not sodium hydrogen peroxide but sodium peroxoborate, and in Example 11, the oxidizing agent was not hydrogen peroxide but sodium peroxocarbonate. In Comparative Example 1, a cerium-containing solution was obtained without using an oxidizing agent.

(Example 12)
A cerium-containing solution was produced at the blending ratio shown in Table 1 below. First, 100 parts by weight of trivalent cerium carbonate (Daiichi Rare Element Chemical Co., Ltd.) was added to 900 parts by weight of water to prepare a raw material liquid in which cerium carbonate was dispersed in water.

  Next, while maintaining the raw material liquid at 25 ° C. and stirring, a mixed solution is prepared by adding 120 parts by weight of sodium carbonate (manufactured by Sigma Aldrich), which is a carbonate ion-containing alkaline compound, and then at 30 ° C. Stirring was continued for 20 minutes.

  Next, while stirring the mixture prepared as described above, the mixture was heated until the temperature of the mixture reached 45 ° C., and kept at this temperature for 20 minutes. Thereafter, 50 parts by weight of 30% hydrogen peroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) as an oxidizing agent was added while maintaining the temperature of the mixed solution at 45 ° C., and stirring was further continued.

  Next, the solution to which hydrogen peroxide solution was added as described above was kept at 35 ° C. with stirring, and the solution was aged by being kept at this temperature for 180 minutes to obtain a cerium-containing solution.

(Examples 13 and 14)
The type of carbonate ion-containing alkali compound, and the amount of cerium contained in the same manner as in Example 12 except that the blending amounts of water, cerium carbonate, carbonate ion-containing alkali compound and oxidizing agent are as shown in Table 1 below. A solution was obtained.

(Example 15)
100 parts by weight of trivalent cerium carbonate (Daiichi Rare Element Chemical Co., Ltd.) is added to 400 parts by weight of 25% ammonia water (Wako Pure Chemical Industries, Ltd.), and cerium carbonate is dispersed in ammonia water. A raw material solution was prepared.

  Next, while the raw material liquid is kept at 25 ° C. and stirred, a mixed solution is prepared by adding 200 parts by weight of sodium carbonate (manufactured by Sigma-Aldrich), which is a carbonate ion-containing alkaline compound, and then at 30 ° C. Stirring was continued for 20 minutes.

  Next, while stirring the mixture prepared as described above, the mixture was heated until the temperature of the mixture reached 45 ° C., and kept at this temperature for 20 minutes. Thereafter, 50 parts by weight of 30% hydrogen peroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) as an oxidizing agent was added while maintaining the temperature of the mixed solution at 45 ° C., and stirring was further continued.

  Next, the solution to which hydrogen peroxide solution was added as described above was kept at 35 ° C. with stirring, and the solution was aged by being kept at this temperature for 180 minutes to obtain a cerium-containing solution.

(Example 16)
300 parts by weight of water and 100 parts by weight of 25% strength aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed to prepare an aqueous ammonium ion-containing alkaline solution. While stirring the alkaline aqueous solution, 100 parts by weight of trivalent cerium carbonate (Daiichi Rare Element Chemical Co., Ltd.) was added to prepare a raw material liquid in which cerium carbonate was dispersed in the alkaline aqueous solution.

  Next, while the raw material liquid is kept at 25 ° C. and stirred, a mixed solution is prepared by adding 100 parts by weight of sodium carbonate (manufactured by Sigma Aldrich), which is a carbonate ion-containing alkali compound, and then at 30 ° C. Stirring was continued for 20 minutes.

  Next, while stirring the mixture prepared as described above, the mixture was heated until the temperature of the mixture reached 45 ° C., and kept at this temperature for 20 minutes. Thereafter, 50 parts by weight of 30% hydrogen peroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) as an oxidizing agent was added while maintaining the temperature of the mixed solution at 45 ° C., and stirring was further continued.

  Next, the solution to which hydrogen peroxide solution was added as described above was kept at 35 ° C. with stirring, and the solution was aged by being kept at this temperature for 180 minutes to obtain a cerium-containing solution.

  The cerium-containing solutions obtained in Examples 1 to 16 were all colored in dark reddish brown, whereas the cerium-containing solution obtained in Comparative Example 1 was colored in a transparent orange color. Many undissolved residues were observed. In Comparative Example 1, the proportion of tetravalent cerium ions in the cerium ions present in the solution is small.

Table 2 shows the cerium content in the cerium-containing solutions obtained in Examples 1 to 16 and Comparative Example 1, the pH of the cerium-containing solution, and the specific gravity of the cerium-containing solution. The cerium content is expressed in terms of cerium oxide. The cerium content was calculated by chelate titration under hydrochloric acid acidity, and the cerium oxide content (CeO ₂ ) calculated by this titration was used as the tetravalent cerium content.

  It can be seen that the cerium content in the cerium-containing solution obtained in Comparative Example 1 is smaller than the cerium-containing solution obtained in each Example. This is considered to be because the cerium-containing solution of Comparative Example 1 did not contain an oxidizing agent, so that the valence of cerium carbonate (cerium raw material) used in the alkaline region did not change and did not dissolve. It is done. The cerium-containing solution obtained in Comparative Example 1 is different from Examples 1 to 16 and has a transparent orange color. When estimated from the amount and concentration of the solution, 90% of the used cerium carbonate. It is inferred that the degree exists as a residue.

  On the other hand, in Examples 1 to 16, since an oxidant is contained, tetravalent cerium can stably exist even in the alkaline region, and therefore it can be said that a large amount of tetravalent cerium is present in the cerium-containing solution. In particular, in Examples 1 to 16, cerium carbonate (liquid) used as a raw material was considered in consideration of the fact that an excessive amount of an oxidizing agent was used with respect to cerium and that the color of the solution was dark reddish brown. It can be considered that all of the cerium ions are tetravalent.

  Moreover, as shown in Table 1, the monovalent cation species is any of ammonium ions (Examples 1 to 11), sodium ions (Example 12), potassium ions (Example 13), and cesium ions (Example 14). Even so, it can be seen that the desired cerium-containing solution is obtained. Therefore, it can be seen that the stability of the cerium-containing solution is excellent without depending on the monovalent cation species contained in the cerium-containing solution. Further, Examples 15 and 16 also showed that the stability of the cerium-containing solution is excellent even when a plurality of monovalent cations are contained.

  In the cerium-containing solution of the present invention, even if the concentration of tetravalent cerium ions is high, precipitates are not easily generated in the solution, and since the storage property is excellent, the industrial versatility is remarkably expanded. Therefore, the cerium-containing solution produced by the above method can be used as a powerful oxidizing reagent in various organic syntheses, and in particular, a raw material for producing cerium oxide and a cerium-containing composite oxide (for example, an exhaust gas purification automobile catalyst). And the like, and as a raw material for producing cerium sol and cerium-containing sol, a raw material for producing cerium-containing inorganic and organic compounds, and other oxidizing agents.

Claims (6)

Carbonate ion, a monovalent cation, only containing tetravalent cerium ions and oxidizing agent, the cerium-containing solution, wherein the pH of 7 or more.   The cerium-containing solution according to claim 1, wherein the monovalent cation contains an ammonium ion. The cerium-containing solution according to claim 1 or 2 , wherein the tetravalent cerium ion is contained in an amount of 0.5% by weight or more in terms of oxide. It said oxidizing agent is hydrogen peroxide, inorganic peroxides, at least one or more selected from the group of oxidizing compounds including peracetic acid salt and a halogen atom, any of claims 1-3 1 The cerium-containing solution according to item. The cerium-containing solution according to claim 4 , wherein the oxidizing agent is at least one compound or two or more compounds from the group of hydrogen peroxide, sodium peroxoborate and sodium peroxocarbonate. The following steps (1) to (5):
(1) a first step of preparing a raw material solution containing at least one of an ammonium ion-containing alkaline aqueous solution and water and a cerium compound;
(2) a second step of preparing a mixed solution by mixing the raw material liquid prepared in the first step and at least one of carbonate and bicarbonate.
(3) Third step of stirring the mixed solution prepared in the second step at 10 to 50 ° C. for 10 to 60 minutes,
(4) a fourth step of blending an oxidizing agent into the mixed liquid heated in the third step,
(5) A fifth step of obtaining a cerium-containing solution by aging the solution prepared in the fourth step at 30 to 50 ° C. for 30 minutes to 15 hours,
The method for producing a cerium-containing solution according to any one of claims 1 to 5 , wherein:

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