JP3211215B2 - Method for producing crystalline zirconium phosphate compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a crystalline zirconium phosphate compound, which is a kind of inorganic ion exchanger, by a hydrothermal method. It has excellent radiation resistance and chemical resistance and is useful as an inorganic ion exchanger showing specific ion selectivity.

[0002]

2. Description of the Related Art A crystalline zirconium phosphate compound is a compound known as an ion exchanger or a solid electrolyte, and a calcination method, a hydrothermal method, or the like is known as a production method thereof.

As a crystalline zirconium phosphate compound,
Compound represented by the following general formula XZr ₂ (PO ₄ ) ₃ .nH ₂ O (where X represents an alkali metal ion and n represents 0 ≦ n ≦
It is a number that satisfies 2. Is obtained by a calcining method, a zirconium compound, a phosphoric acid compound and an alkali metal salt are mixed in a dry or wet manner so as to have a stoichiometric ratio of the above compound, and the above powder mixture is mixed with an appropriate binder. After press-molding, a solid phase reaction is performed by heating and baking at 1000 to 1600 ° C.

However, the crystalline zirconium phosphate compound synthesized by the calcination method has disadvantages such as poor crystallinity and easy mixing of impurities such as unreacted raw materials and by-products. Further, since crystalline zirconium phosphate obtained by the firing method is remarkably sintered, it is very difficult to obtain a powder having a uniform and fine particle size distribution by a general mechanical pulverization method. Generally, the inorganic ion exchanger is used as a fine powder dispersed in an aqueous solution, a resin, a paint, or the like. Therefore, the dispersibility of the powder is important.
It is said that it is preferably 0 μm or less, and the average particle size is preferably 1 μm or less. Therefore, as described above, it is often difficult to obtain a powder having a uniform and fine particle size distribution, which is a great obstacle in applying the powder to various uses. For the above reasons, when the crystalline zirconium phosphate compound is used as a powdery inorganic ion exchanger, the calcination method is hardly a suitable production method.

On the other hand, a crystalline zirconium phosphate compound YZr ₂ (PO ₄ ) ₃ .nH ₂ O represented by the following general formula (where Y represents an ammonium ion and n represents 0 ≦ n ≦
It is a number that satisfies 2. Is obtained by mixing an aqueous solution of a zirconium compound and an aqueous solution of ammonium phosphate and adjusting the pH to 3.8 to 5.0 to form a precipitate. There is a method of obtaining a crystalline zirconium phosphate compound by heating the precipitate and subjecting it to solid-liquid separation, and a hydrothermal reaction using zirconium oxychloride hydrate as a zirconium ion-containing compound is known ( Tokiko 2-320
3).

[0006] According to the hydrothermal method, a pure crystalline zirconium phosphate compound can be obtained in a short time, and the crystalline zirconium phosphate compound synthesized by this method has a fine granular form having good crystallinity. Since the particles are uniform and the primary particles have a uniform particle size, the pulverization is extremely easy and is suitable for dispersing the inorganic ion exchanger in the form of fine powder. However, the known hydrothermal method has a problem that it has to be performed under considerably severe hydrothermal conditions such as a heating temperature of 320 to 400 ° C. and a pressure of 50 to 150 MPa, and it is industrially easy. It is hard to say that it is a manufacturing condition.

As a means for solving the problems of the above-mentioned hydrothermal method, a method of adding a complexing agent to a reaction system has been proposed (JP-A-60-239313). That is, the method comprises adding a carboxylic acid compound as a complexing agent to a mixed solution of an aqueous solution of a zirconium compound and an aqueous solution containing at least one of a phosphoric acid compound and an ammonium ion-containing compound or an amine-containing compound. Heating temperature 100
A method for producing crystalline ammonium zirconium phosphate, characterized in that the reaction is carried out under mild conditions of not more than ℃.

However, in this method, impurities are easily generated, the yield per reaction volume is very small, and there are problems in the production process such as removal of carboxylic acid compounds in wastewater, as compared with the conventional hydrothermal method. Therefore, there is room for various improvements.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems and provides a highly pure crystalline zirconium phosphate compound under mild reaction conditions. Provides a production method which can be used as a powder having a uniform and fine particle size distribution.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems of the prior art, and as a result,
When a sulfate ion-containing zirconium compound is used, the addition of a complexing agent as disclosed in Japanese Patent Application Laid-Open No. Sho 60-239313 allows for a very low heating temperature range as compared with the heating temperature in the conventional hydrothermal method. The present inventors have found that a crystalline zirconium phosphate compound useful as an inorganic ion exchanger can be easily and economically produced, and have completed the present invention. That is, the present invention produces a precipitate by mixing an aqueous solution of a phosphate compound and an aqueous solution of a zirconium compound, and heating the precipitate under hydrothermal conditions to produce a crystalline zirconium phosphate compound. In this case, an aqueous solution containing ammonium ions and / or alkali metal ions is used as an aqueous solution of a phosphate compound, and an aqueous solution of a zirconium compound containing a sulfate ion in the compound is used as an aqueous solution of a zirconium compound. This is a method for producing a crystalline zirconium phosphate compound represented by the formula: AZr ₂ (PO ₄ ) ₃ .nH ₂ O [1] (where A represents at least one kind of ammonium ion or alkali metal ion, and n is a number satisfying 0 ≦ n ≦ 2)

Hereinafter, the production method of the present invention will be described in detail. The production method of the present invention is a method for producing a precipitate by mixing an aqueous solution of a phosphate compound and an aqueous solution of a zirconium compound, and heating the reaction slurry under hydrothermal conditions to convert the crystalline zirconium phosphate compound. It is a manufacturing method. As the sulfate ion-containing zirconium compound used in the present invention, any water-soluble zirconium compound having a sulfate ion in the compound can be used without particular limitation, and specific examples of preferred compounds include
Zirconium sulfate, basic zirconium sulfate and zirconium oxysulfate.

The phosphate compound used in the present invention is phosphoric acid or phosphate, and preferred phosphates include water-soluble or acid-soluble salts, such as ammonium phosphate and alkali metal phosphate. Specific examples thereof include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and dipotassium hydrogen phosphate.

A of the compound represented by the general formula [1] represents the concentration of an alkali metal ion and the concentration of an ammonium ion in the reaction slurry, and the distribution ratio of these ions in the compound represented by the general formula [1]. Is determined by Therefore, in the present invention, as a method of supplying an alkali metal ion or ammonium ion to the reaction system, not only a method of supplying a phosphate of an alkali metal ion or ammonium ion as a raw material, but also a compound different from phosphoric acid There is a method of supplying a compound containing these ions as a raw material, and by appropriately adjusting the concentrations of alkali metal ions and ammonium ions in the reaction slurry, crystalline zirconium phosphate having a desired ratio of alkali metal ions and ammonium ions It is possible to obtain a compound. For example, the alkali metal ion in the reaction slurry is present in an excess of about 10 times the stoichiometric amount of A in the compound represented by the general formula [1] to adjust the pH of the reaction slurry to reduce the amount of ammonium ion. When varied, A in the product is almost an alkali ion when the ammonium ion is in a stoichiometric amount of A;
When the ammonium ion is twice the stoichiometric amount of A, A in the product is almost ammonium ion, and when the ammonium ion is intermediate between the stoichiometric amount of A and twice that amount, the product As A in the compound, a compound in which an ammonium ion and an alkali ion coexist can be obtained.
Preferred specific examples of the alkali metal salt and ammonium salt that can be used to adjust the concentration of the alkali metal ion and ammonium ion in the reaction slurry include halides or sulfates of alkali metal and ammonium ions, and specific compounds include Examples include sodium chloride, potassium chloride, lithium chloride, ammonium chloride, sodium sulfate, potassium sulfate, lithium sulfate, and ammonium sulfate. The alkali metal salt and / or
Alternatively, in order to supply an ammonium salt to the reaction system, one or more water-soluble salts selected from the above alkali metal salts and ammonium salts are added to any of an aqueous solution of a sulfate ion-containing zirconium compound, an aqueous solution of a phosphoric acid compound, or a reaction slurry. You may.

In mixing the aqueous solution of the sulfate ion-containing zirconium compound and the aqueous solution of the phosphate compound, the mixing molar ratio of zirconium ion and phosphate ion in each raw material is such that Zr: PO ₄ = 1: 1.5. If the stoichiometric ratio or a value close to this ratio, for example, Zr: PO ₄ = 1: 2, there is no particular limitation on the method of mixing the aqueous solution of the sulfate ion-containing zirconium compound and the aqueous solution of the phosphate compound. Either a method of adding an aqueous solution of a phosphate compound to an aqueous solution of an ion-containing zirconium compound, or a method of simultaneously adding an aqueous solution of a phosphate compound and an aqueous solution of a sulfate ion-containing zirconium compound to a reaction vessel filled with pure water are employed. Good. However, it is desirable to sufficiently stir the reaction slurry so that the phosphoric acid concentration does not partially increase.

The slurry after mixing the raw material aqueous solution to form a precipitate as described above is preferably adjusted to a pH of 7 or less, more preferably adjusted to a pH of 1 to 5, and then subjected to hydrothermal treatment. Provided for reaction. When the pH is less than 1, a crystalline zirconium phosphate compound having a layered structure represented by the following general formula tends to be formed, and A ₂ Zr (PO ₄ ) ₂ (where A is at least selected from ammonium ion and alkali metal ion) If the pH is higher than 7, the tendency to form an amorphous zirconium phosphate compound increases.

In order to adjust the pH of the reaction slurry, an acid or an alkali may be added to the reaction slurry. Preferred acids include mineral acids such as hydrochloric acid, sulfuric acid and nitric acid. And hydroxides of alkali metals. Specific compounds include, for example, ammonium hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like.

The solid concentration of the reaction slurry is not particularly limited, but as the concentration increases, the crystallization rate tends to decrease. On the other hand, when the concentration decreases, the yield per unit volume of the reaction vessel decreases, Considering the time required for crystallization and the volumetric efficiency, a preferable solid content concentration is in the range of 10 to 40 wt% because it is not economical.

The reaction slurry is preferably heated in a closed vessel at a temperature of 105 ° C. or higher under hydrothermal conditions. 105
If the heating is carried out at a temperature of at least ℃, the crystallization proceeds sufficiently, but the heating at a low temperature and a low pressure reduces the crystallization speed, which is disadvantageous as an economical production method. C is more preferable, and 130 to 150 C is more preferable. If the heating conditions are appropriately set, the crystallization is completed within 12 to 48 hours.

After obtaining the crystalline zirconium phosphate compound as described above, the product is filtered, decanted,
By known means such as centrifugation and filter-press,
The general formula [1] useful as a powdery inorganic ion exchanger after being separated from the liquid phase, washed, dried and pulverized by a conventional method.
Is obtained.

[0020]

The present invention will be described more specifically with reference to the following examples. The present invention can be performed by methods other than those described in the embodiments, and the present invention is not limited to the embodiments. The powders obtained in the following examples were subjected to various measurements as follows. (1) X-Ray Fluorescence Analysis The presence or absence of alkali metal ions in the powder was measured using 3270E manufactured by Rigaku Corporation. (2) Identification of crystal structure Powder X using Cu-Kα radiation and a Ni plate as a filter
The crystal structure was identified by performing a line diffraction analysis and comparing the obtained diffraction pattern with an ASTM card or existing literature. (3) Particle size distribution Laser diffraction type particle size distribution measuring device (LA-Made by Shimadzu Corporation)
500) to determine the average and maximum particle size,
The particle size distribution of the powder was evaluated.

Example 1 Reagent primary zirconium sulfate [Zr (SO ₄ ) ₂ .4H
21.2g of ₂ O] (0.06 mol) was dissolved in pure water 40 g, was prepared zirconium sulfate aqueous solution (a). Then, 10.4 g of reagent primary ammonium dihydrogen phosphate
(0.09 mol) of an aqueous solution (b) dissolved in pure water.
g was added to the aqueous solution (a) with stirring to form a precipitate, and a reaction slurry was obtained. 2
The reaction slurry was adjusted to pH 2 by adding 28 g of a 0 wt% aqueous sodium hydroxide solution, and then transferred to a Teflon pressure-resistant container at 150 ° C. under a saturated vapor pressure (4.9 K).
g / cm ² ) for 24 hours. The reaction product was filtered, washed with water, dried at 105 ° C., and the dried cake was lightly pulverized to obtain 14.2 g of a white powder.
As a result of fluorescent X-ray analysis of the white powder, almost no sodium ion was present in the white powder. Further, as a result of analyzing the powder X-ray diffraction diagram (FIG. 1) of the obtained dry powder, a crystalline ammonium zirconium phosphate compound [N
H ₄ Zr ₂ (PO ₄ ) ₃ ] showed exactly the same X-ray diffraction peak, and did not contain crystalline impurities. From the above, it can be understood that the white powder is a zirconium phosphate compound having an ammonium ion as A in the general formula [1]. As a result of the particle size distribution measurement, the average particle size and the maximum particle size of the obtained powder were 0.68 μm and 2.6, respectively.
μm, and the white powder obtained above had a uniform and fine particle size distribution.

Comparative Example 1 The procedure of Example 1 was repeated, except that the same molar number of zirconium oxychloride was used instead of zirconium sulfate, to obtain 14.7 g of a white powder. The powder X-ray diffraction pattern (FIG. 2) of the obtained dry powder showed a halo pattern peculiar to the amorphous phase, and did not show any formation of a crystalline substance.

Comparative Example 2 The same operation as in Example 1 was carried out except that the same molar number of zirconium nitrate was used instead of zirconium sulfate.
14.4 g of a white powder was obtained. Powder X of the obtained dry powder
The line diffractogram (FIG. 3) showed a halo pattern characteristic of amorphous and showed no formation of crystalline material.

Example 2 In Example 1, 10.3 g (0.09 mol) of an 85% aqueous solution of phosphoric acid was used instead of the aqueous solution of ammonium dihydrogen phosphate.
And the same operation was performed except that the pH was adjusted to 4 by adding 65 g of a 20 wt% aqueous sodium hydroxide solution to obtain 14.5 g of a white powder. The powder X-ray diffraction diagram (FIG. 4) of the obtained dry powder shows the same X-ray diffraction peak as that of the crystalline sodium zirconium phosphate compound [NaZr ₂ (PO ₄ ) ₃ ], and contains crystalline impurities. Did not. This indicates that the white powder is a zirconium phosphate compound having a sodium ion as A in the general formula [1]. As a result of the particle size distribution measurement, the average particle size and the maximum particle size of the obtained powder were 0.70 μm and 3.0 μm, respectively, and the white powder obtained above had a uniform and fine particle size distribution.

Example 3 In Example 2, 50 g of a 20% aqueous solution of potassium hydroxide was added instead of a 20% aqueous solution of sodium hydroxide to adjust the pH.
3 except that the white powder was adjusted to 14.4.
g was obtained. Powder X-ray diffraction diagram of the obtained dry powder (FIG. 5)
Is a crystalline potassium zirconium phosphate compound [KZr
₂ (PO ₄ ) ₃ ], and did not contain crystalline impurities. This indicates that the white powder is a zirconium phosphate compound having a potassium ion as A in the general formula [1]. As a result of the particle size distribution measurement, the average particle size and the maximum particle size of the obtained powder were 0.55 μm and 1.7 μm, respectively, and the white powder obtained above had a uniform and fine particle size distribution.

Example 4 Reagent primary zirconium sulfate [Zr (SO ₄ ) ₂ .4H
The ₂ O] 423g was dissolved in pure water 600 g, to prepare a zirconium sulfate aqueous solution (a). Next, 800 g of an aqueous solution (b) obtained by dissolving 208 g of reagent primary ammonium dihydrogen phosphate in pure water was added to the aqueous solution (a) with stirring to form a precipitate, thereby obtaining a reaction slurry. After adding 280 g of a 40% aqueous sodium hydroxide solution to the reaction slurry to adjust the reaction slurry to pH 2,
Transfer to a stainless steel 3L volume autoclave, 1
Hydrothermal treatment was performed at 40 ° C. under a saturated vapor pressure (3.7 kg / cm ² ) with stirring for 36 hours. After the reaction product was filtered and washed with water, it was dried at 105 ° C., and the dried cake was lightly pulverized to obtain 290 g of a white powder. As a result of fluorescent X-ray analysis of the white powder, almost no sodium ion was present in the white powder. In addition, as a result of analyzing the powder X-ray diffraction diagram (FIG. 6) of the obtained dry powder, a crystalline ammonium zirconium phosphate compound [NH ₄ Zr ₂ (PO
₄ ) It showed the same X-ray diffraction peak as ₃ ), and did not contain any crystalline impurities. From the above, it is understood that the white powder is a zirconium phosphate compound having an ammonium ion as A in the general formula [1]. As a result of the particle size distribution measurement, the average particle size and the maximum particle size of the obtained powder were 0.60 μm and 2.2 μm, respectively, and the white powder obtained above had a uniform and fine particle size distribution.

Example 5 The heating temperature was 110 ° C. and the reaction pressure was a saturated vapor pressure (1.5 K
g / cm ² ), and 14.4 g of a white powder was obtained in exactly the same manner as in Example 1. As a result of fluorescent X-ray analysis of the white powder, almost no sodium ion was present in the white powder. Further, as a result of analyzing the powder X-ray diffraction diagram (FIG. 7) of the obtained dry powder, it showed the same X-ray diffraction peak as that of the crystalline ammonium zirconium phosphate compound [NH ₄ Zr ₂ (PO ₄ ) ₃ ]. It did not contain crystalline impurities. From the above, the white powder is represented by the general formula [1]
It can be understood that A in the above is a zirconium phosphate compound having an ammonium ion. As a result of the particle size distribution measurement, the average particle diameter and the maximum diameter of the obtained powder are each,
0.46 μm and 1.7 μm, and the white powder obtained above had a uniform and fine particle size distribution.

Example 6 Reagent primary zirconium sulfate [Zr (SO ₄ ) ₂ .4H
21.2g of ₂ O] (0.06 mol) was dissolved in pure water 40 g, was dissolved then ammonium chloride 1.60 g, was prepared zirconium sulfate aqueous solution (a) containing ammonium ions. Next, an 85% phosphoric acid aqueous solution (b)
10.4 g (0.09 mol) was added to the aqueous solution (a) with stirring to form a precipitate, and a reaction slurry was obtained. The reaction slurry was adjusted to pH 2 by adding 15 g of a 20 wt% aqueous sodium hydroxide solution to the reaction slurry, and then transferred to a Teflon pressure-resistant container.
Hydrothermal treatment was carried out at 24 ° C. under a saturated vapor pressure (4.9 kg / cm ² ) for 24 hours. After the reaction product was filtered and washed with water, 10
By drying at 5 ° C. and lightly pulverizing the dried cake,
14.3 g of a white powder was obtained. Fluorescence X of the obtained dry powder
As a result of the line analysis, the dried powder contains sodium ions. As a result of the infrared absorption spectrum analysis of the dried powder, the absorption specific to the NH bond of ammonium ions (14
30 cm ^-1 ), indicating that the dry powder contained ammonium ions. The powder X-ray diffraction pattern (FIG. 8) of the dried powder shows an X-ray diffraction pattern very similar to that of the crystalline sodium zirconium phosphate compound [NaZr ₂ (PO ₄ ) ₃ ]. The main peak was slightly shifted to a lower angle, and did not contain crystalline impurities. From the above, it is understood that the white powder obtained as described above is a crystalline zirconium phosphate compound having an ammonium ion and a sodium ion as A in the general formula [1]. As a result of the particle size distribution measurement, the average particle size and the maximum particle size of the obtained powder were 0.54 μm and 1.2 μm, respectively, and the white powder obtained above had a uniform and fine particle size distribution.

[0029]

The present invention makes it possible to obtain a high-purity crystalline zirconium phosphate compound under mild reaction conditions as compared with the conventional hydrothermal method, and furthermore, to obtain a reaction product obtained by the present invention. Has a unique ion exchange property and a uniform and fine particle size distribution, and can be used by dispersing it in an aqueous solution, resin, paint, or the like.
Therefore, the present invention has an extremely large industrial value as a production method capable of easily and extremely economically obtaining a finely powdered crystalline zirconium phosphate compound having a function as an ion exchanger.

[Brief description of the drawings]

FIG. 1 is a powder X-ray diffraction diagram of a dry powder obtained in Example 1.

FIG. 2 is a powder X-ray diffraction diagram of the dry powder obtained in Comparative Example 1.

FIG. 3 is a powder X-ray diffraction diagram of the dry powder obtained in Comparative Example 2.

FIG. 4 is a powder X-ray diffraction diagram of the dry powder obtained in Example 2.

FIG. 5 is a powder X-ray diffraction diagram of the dry powder obtained in Example 3.

6 is a powder X-ray diffraction chart of the dry powder obtained in Example 4. FIG.

FIG. 7 is a powder X-ray diffraction chart of the dry powder obtained in Example 5.

FIG. 8 is a powder X-ray diffraction diagram of the dry powder obtained in Example 6.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidetake Inoue 1 1 Funamicho, Minato-ku, Nagoya-shi, Aichi Prefecture East Nagoya Chemical Industry Co., Ltd. Nagoya Research Institute (72) Inventor Hideki Kato Minato-ku, Nagoya-shi, Aichi Daiji Daikohara, Investigator, Nagoya Research Institute, No. 1, Funamicho, Tokyo, Japan (56) References JP-A-62-83309 (JP, A) JP-A-62-138314 (JP, A) JP-A-60-96513 (JP, A) JP-A-60-96514 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01B 25/37

Claims (1)

(57) [Claims] A precipitate is formed by mixing an aqueous solution of a phosphate compound and an aqueous solution of a zirconium compound,
By heating the precipitate under hydrothermal conditions, when producing a crystalline zirconium phosphate compound, an aqueous solution containing ammonium ions and / or alkali metal ions is used as the aqueous solution of the phosphate compound, and the aqueous solution of the zirconium compound is used as the aqueous solution of the zirconium compound. A method for producing a crystalline zirconium phosphate compound represented by the following general formula, wherein an aqueous solution of a zirconium compound containing sulfate ions in the compound is used. AZr ₂ (PO ₄ ) ₃ .nH ₂ O (where A represents at least one of ammonium ion or alkali metal ion, and n is a number satisfying 0 ≦ n ≦ 2)