JP3384412B2 - Method for producing crystalline zirconium phosphate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing crystalline zirconium phosphate having an alkali metal ion and an ammonium ion, and the compound obtained by the present invention has a fine particle size. It is useful as an inorganic ion exchanger excellent in heat resistance, radiation resistance and chemical resistance, and particularly useful as a raw material compound of an antibacterial agent. [0002] Crystalline zirconium phosphate (hereinafter referred to as CPZ)
Is a compound represented by the following general formula [2]:
It has properties as an ion exchanger. MZr ₂ (PO ₄ ) ₃ .nH ₂ O [2] (M is at least one kind of monovalent cation or monovalent cation and divalent cation, and n is a number satisfying 0 ≦ n ≦ 2. The present inventors have previously proposed, as an antibacterial agent, a compound represented by the following general formula [3], which is a kind of CPZ. _{Ag x H y AzZr 2 (PO} 4) 3 [3] (A is an alkali metal, x, y and z are each x + y + z
It is a positive number less than 1 that satisfies = 1. The compound represented by the above general formula [3] is ion-exchanged by contacting CPZ having hydrogen and alkali ions as M ions in the general formula [2] with a solution containing silver ions such as an aqueous silver nitrate solution. Can be obtained easily. On the other hand, CP having hydrogen and alkali ions
Z is C having ammonium ion and alkali ion
It is easily obtained by firing PZ. Therefore, to obtain the compound represented by the general formula [3], it is necessary to first produce CPZ having an ammonium ion and an alkali ion as a raw material compound. Various methods are known for producing CPZ, including a firing method, a hydrothermal method, and a wet method. In the firing method, a zirconium compound, phosphoric acid or a salt thereof and an alkali metal salt are mixed in a dry or wet manner so as to have a stoichiometric ratio, and the powder mixture is mixed at 1000 to 160
This is a method of firing at 0 ° C. to perform a solid phase reaction. However, CPZ obtained by the firing method has drawbacks such as poor crystallinity and easy mixing of impurities such as unreacted raw materials and by-products. Further, it is impossible to obtain a CPZ having an ammonium ion as an M ion which causes thermal decomposition at the firing temperature. Further, the CPZ obtained by the firing method
Since sintering is remarkable, it is very difficult to obtain uniform and fine particles by a general mechanical pulverization method. Not suitable for use. The hydrothermal method is a method in which an aqueous solution containing a zirconium compound, phosphoric acid or a salt thereof, an ammonium compound and the like is heated under pressure. For example, an aqueous solution of zirconium oxychloride and an aqueous solution of ammonium phosphate are mixed. , A precipitate is formed by adjusting the pH to 3.8 to 5.0, and then the precipitate is heated under hydrothermal conditions and solid-liquid separated to obtain CPZ. 2-32203). Generally, it is said that a compound having high crystallinity can be obtained by a hydrothermal method. However, a compound having high crystallinity has not been obtained for CPZ having an ammonium ion and an alkali metal ion. In the wet method, an aqueous solution of a zirconium compound is used,
This is a method in which an aqueous solution containing phosphoric acid or a salt thereof and an ammonium-containing compound is reacted under a normal condition at a pH of 10 or less and a heating temperature of 100 ° C. or less under mild conditions. A method of accelerating the reaction by adding a salt is known (JP-A-60-239313). Among the various production methods described above, the reaction can be controlled under mild conditions, and the wet method is preferable as a method for production on an industrial scale. As described above, since CPZ has ion exchangeability, CPZ having only one of an alkali metal ion and an ammonium ion as M ion
After synthesizing (hereinafter referred to as), a method of obtaining a compound having an alkali metal ion and an ammonium ion by supplementing cations not possessed by CPZ by ion exchange may be considered. However, it is economically disadvantageous to carry out the synthesis through two steps of the synthesis reaction and the ion exchange. Further, it is considered that this is caused by the unique ion exchange property of CPZ. However, ammonium ions are introduced as M ions of the above CPZ by ion exchange, or
It is not easy to replace an ammonium ion, which is an M ion of Z, with an alkali metal ion. For this reason, it is desired to synthesize a compound having an ammonium ion and an alkali ion in a single step, but a production method for obtaining the following compound in which the M ion of CPZ is an alkali metal ion and an ammonium ion by a single-step wet synthesis is known. Not been. A _x NH _{4 (1-x)} Zr ₂ (PO ₄ ) ₃ .nH ₂ O [1] (where A represents an alkali metal ion and X represents 0 <X <
1, n is a number satisfying 0 ≦ n ≦ 2. SUMMARY OF THE INVENTION The present invention provides a method for producing highly crystalline and fine-grained CPZ having an alkali metal ion and an ammonium ion by a single-stage wet synthesis reaction. Things. Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have found that by controlling the ratio of raw materials charged, the PH value of the reaction slurry and the heating temperature, a CP having high crystallinity can be obtained.
They have found that Z can be produced by a single-stage wet synthesis reaction, and have completed the present invention. That is, the present invention provides a method of mixing a raw material liquid (A) composed of an aqueous solution containing zirconium and a carboxylic acid or a salt thereof and a raw material liquid (B) composed of an aqueous solution containing phosphoric acid or a salt thereof to form phosphate ions. 1
A reaction slurry containing 0.61 to 0.8 equivalents of zirconium per equivalent is produced, ammonium ions and alkali metal ions are contained in the reaction slurry, and alkali metal ions are at least 1.4 equivalents per equivalent of ammonium ion. And heating the reaction slurry whose pH has been adjusted to 7 or less at a temperature of 80 ° C. or more, which is a method for producing crystalline zirconium phosphate represented by the following general formula [1]. A _x NH _{4 (1-x)} Zr ₂ (PO ₄ ) ₃ .nH ₂ O [1] (where A represents an alkali metal ion and X represents 0 <X <
1 and n is a number that satisfies 0 ≦ n ≦ 2. Hereinafter, the production method of the present invention will be described in detail. Preparation of Raw Material Liquid (A) The raw material liquid (A) used in the production method of the present invention comprises:
It is preferable that the raw material liquid (A) be prepared by mixing an aqueous solution of a zirconium compound and an aqueous solution of a carboxylic acid or a salt thereof in advance, comprising an aqueous solution containing a zirconium compound and a carboxylic acid or a salt thereof. If raw material liquid (A)
Without previously preparing the aqueous solution of the zirconium compound and the aqueous solution of phosphoric acid or a salt thereof, and then mixing the aqueous solution of a carboxylic acid or a salt thereof. However, there is a problem that the compound intended by the present invention cannot be obtained and an ammonium salt of zirconium phosphate (languine stone-type crystal) represented by the following general formula [4] is produced even if the coexistence is carried out at a ratio of . The CPZ obtained by the method of the present invention is fine particles having an average particle size of about 0.5 μm, whereas the langbine-type crystal has an average particle size of about 3 μm.
Since the crystal is as large as m, its formation must be suppressed as much as possible. The mixing ratio of the zirconium compound and the carboxylic acid or a salt thereof is not particularly limited, but one equivalent of the zirconium compound (formula weight per Zr atom)
It is preferable to use a ratio of one equivalent of carboxylic acid or a salt thereof (molecular weight per one carboxyl group) per unit. NH ₄ Zr ₂ (PO ₄ ) ₃ [4] (Zirconium compound) As the zirconium compound that can be used in the present invention, a water-soluble or acid-soluble zirconium compound is suitable. , Zirconium acetate, zirconium sulfate,
Basic zirconium sulfate, zirconium oxysulfate, zirconium oxychloride and the like. (Carboxylic acid or a salt thereof) The carboxylic acid or a salt thereof preferably used in the present invention is an aliphatic polycarboxylic acid having two or more carboxyl groups and a salt thereof. There is a compound of That is, aliphatic dibasic acids such as oxalic acid, maleic acid, malonic acid, and succinic acid, sodium oxalate, sodium hydrogen oxalate, lithium hydrogen oxalate, ammonium oxalate, and ammonium hydrogen oxalate. Acid salts, citric acid, tartaric acid, aliphatic oxyacids such as malic acid, and salts thereof. Of these, oxalic acid and its sodium and ammonium salts are particularly preferred compounds. Preparation of Raw Material Liquid (B) In the production method of the present invention, it is necessary to prepare a raw material liquid (B) comprising an aqueous solution containing phosphoric acid or a salt thereof. (Phosphate) Preferred phosphates that can be used in the present invention include ammonium phosphate and alkali metal phosphate, which are water-soluble or acid-soluble salts, and specific examples thereof include dihydrogen phosphate. Examples include sodium, disodium hydrogen phosphate, trisodium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and dipotassium hydrogen phosphate. ○ Equivalent ratio of alkali metal ion to ammonium ion in reaction slurry (A) The ratio of alkali metal ion to ammonium ion in CPZ is controlled by the concentration ratio of alkali metal ion and ammonium ion in reaction slurry, In order to obtain the target compound of the present invention, the alkali metal ion needs to be at least 1.4 equivalents per equivalent of ammonium ion. As the ratio of the alkali metal ion in the CPZ is larger, the ion exchange capacity of the CPZ is larger, and the usefulness as an inorganic ion exchanger, especially the usefulness as a raw material compound for supporting an antibacterial metal ion is increased. It is preferable that the equivalent ratio (A) is 2.0 or more. Generally, in the reaction between an alkali metal ion and an ammonium ion, the ammonium ion tends to be much more easily incorporated into the CPZ during the reaction. Therefore, if the alkali metal ion is less than 1.4 equivalents per equivalent of the ammonium ion, , CPZ having alkali metal ions cannot be obtained. In the present invention, there is no particular limitation on the method of adjusting the concentration ratio of the alkali metal ion and the ammonium ion in the reaction slurry, and the compound having each ion is adjusted so that the concentration ratio of each ion becomes a predetermined ratio. It may be contained in the reaction slurry. There is no limitation on the mode in which each ion is contained in the reaction slurry.For example, an alkali metal salt and an ammonium compound are added to an aqueous solution of a zirconium compound, an aqueous solution of phosphoric acid or a salt thereof, or an aqueous solution of a zirconium compound. Adding an alkali metal salt, adding an ammonium compound to an aqueous solution of phosphoric acid or a salt thereof, adding an ammonium compound to an aqueous solution of a zirconium compound, adding an alkali metal salt to an aqueous solution of phosphoric acid or a salt thereof, and adding a raw material liquid ( B)
As a phosphoric acid or a salt thereof for preparing a compound, a compound having an ammonium ion or a sodium ion such as ammonium phosphate or sodium phosphate is used. By appropriately adjusting the concentrations of alkali metal ions and ammonium ions in the reaction slurry in this manner, it is possible to obtain CPZ having a desired ratio of alkali metal ions and ammonium ions. Assuming that the ratio of ions to ammonium ions (Na / NH ₄ ) is 6.3, CPZ having a ratio of sodium ions to ammonium ions (Na / NH ₄ ) in the compound of about 1.3 can be obtained. There is no upper limit on the ratio of alkali metal ions to ammonium ions, and an excess amount of alkali metal ions can be arbitrarily charged according to a desired composition of alkali metal ions and ammonium ions. The alkali metal salt and the ammonium compound which can be used for adjusting the concentration of the alkali metal ion and the ammonium ion in the reaction slurry may be water-soluble or acid-soluble. Halides or sulfates. Preferred specific examples of the alkali metal compound include hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, carbonates such as sodium carbonate and potassium carbonate, nitrates such as sodium nitrate, and sodium sulfate. And chlorides such as sodium chloride. Preferred specific examples of the ammonium compound include inorganic ammonium compounds such as ammonium chloride, ammonium sulfate, ammonium nitrate and ammonium hydrogen carbonate. ○ Equivalent ratio of zirconium ions to phosphate ions in the reaction slurry (B) When mixing the raw material liquid (A) and the raw material liquid (B), the zirconium ions in the reaction slurry are converted to per equivalent of phosphate ions. It is necessary to be 0.61 equivalent to 0.8 equivalent. The equivalent ratio (B) is 0.6
When it is smaller than 1, even if alkali metal ions and ammonium ions coexist in the reaction slurry at the above-described predetermined ratio, the compound intended by the present invention cannot be obtained, and the following general formula [5] There is a problem that a compound having a layered structure represented is generated. NH ₄ ZrH (PO ₄ ) ₂ [5] This compound has poor crystallinity and a large particle size. On the other hand, when the equivalent ratio (B) is larger than 0.8, there is a problem that the rate of generation of impurities represented by the above general formula [4], which is a crystal having a large particle size without alkali metal ions, increases. is there. ○ PH value After mixing the raw material liquid (A) and the raw material liquid (B) to form a reaction slurry, it is necessary to adjust the pH value of the reaction slurry to 7 or less, and more preferably to adjust the pH to 1 or less. ~ 6, more preferably 4.5 ~ 6, and then subjected to a heating reaction. During the production of a zirconium phosphate compound in which an alkali metal ion and an ammonium ion coexist, the viscosity of the slurry may increase significantly during the synthesis. It is preferable that the slurry is sufficiently stirred because the change in viscosity causes the slurry to be non-uniform and causes impurities to be generated. The pH of the reaction slurry is preferably from 1 to 6. In this range, the crystal is sufficiently crystallized without any impurities during the synthesis. CPZ in which metal ions and ammonium ions coexist can be easily obtained. Reaction temperature The reaction slurry must be heated at 80 ° C. or higher in the reaction vessel, and more preferably at 95 ° C. or higher. If heated below 80 ° C., the above [4]
The compounds shown in the formula tend to form as impurities.
If heated at 95 ° C. or higher, crystallization proceeds in a short time, and the crystallization speed increases as the temperature increases.
Is more preferred. In this temperature range, crystallization is usually completed within 48 hours. Since the production method of the present invention is a wet reaction under normal pressure, the reaction temperature cannot be raised above the boiling point of the reaction slurry. The total equivalent ratio of alkali metal ion and ammonium ion to zirconium ion in the reaction slurry (C) In order to easily obtain the object of the present invention, the alkali metal to 1 equivalent of zirconium ion in the reaction slurry is used. It is preferable that the ratio (C) of the total equivalent of the ion and the ammonium ion is at least the theoretical value (0.5) or more.
If it is less than 0.5, zirconium ions become excessive, and compounds other than the target compound of the present invention may be generated as impurities. The reaction can be performed by controlling the equivalent ratio (C) to an arbitrary value of 0.5 or more as long as the PH value of the reaction slurry is in the range of 7 or less. The solid content of the reaction slurry is preferably 3 wt% or more.
If it is less than 3 wt%, the compound represented by the above formula [4] tends to be formed as an impurity. When the solid content concentration is 3 wt% or more, CPZ in which alkali metal ions and ammonium ions coexist without impurities can be obtained, but the solid content concentration is 3 to 15 in consideration of the stirring property of the reaction slurry.
A range of wt% is preferred. Separation / Washing / Drying After obtaining the CPZ as described above, the product is separated from the liquid phase by a known separation means such as filtration, decantation, centrifugation and a filter press, and washed. It is dried and pulverized by a conventional method to obtain a compound represented by the general formula [1], which is useful as a powdery inorganic ion exchanger. 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. Various measurements were performed on the powders obtained in the following examples as follows. (1) Identification of crystal structure Using Cu-Kα ray, and using Ni plate as a filter, powder X
The crystal structure was identified by performing a line diffraction analysis and comparing the obtained diffraction pattern with an ASTM card or existing literature. (2) Particle size distribution Average particle size and maximum particle size were measured using a laser diffraction type particle size distribution measuring device (LA-500 manufactured by Shimadzu Corporation).
The particle size distribution of the powder was evaluated. (3) Chemical analysis Chemical composition analysis was performed on the synthesized powder, and the contents of alkali metal ions and ammonium ions in the powder were measured. [0032] Example 1 Reagent first grade zirconium oxychloride [ZrOCl ₂ · 8H ₂
O] was dissolved in 650 g of pure water to prepare an aqueous zirconium oxychloride solution (a). Then, the reagent primary oxalic acid dihydrate [C ₂ H ₂ O ₄
[H ₂ O] was added to an aqueous solution (a) while stirring, and an aqueous solution (b) obtained by dissolving 12.6 g (0.1 mol) of the same in pure water was added to the aqueous solution (a).
ol) to prepare a raw material liquid (A). Next, reagent 1
A raw material (B) consisting of 34.6 g (0.3 mol) of 85% grade phosphoric acid was added to the raw material liquid (A) to form a precipitate, thereby obtaining a reaction slurry [equivalent ratio (B) = 0.67]. . 122 g of a 20% aqueous sodium hydroxide solution was added to the reaction slurry.
(Equivalent ratio (A) = 4.
4] After adjusting the reaction slurry to pH 4, 95 ° C.
For 48 hours. When the change in viscosity during aging was measured using a B-type viscometer, there was a significant increase in viscosity after about 12 hours, and it decreased as crystallization progressed. 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 42.0 g of a white powder. As a result of a chemical composition analysis of the white powder, the equivalent ratio of sodium ions to ammonium ions was about 3: 7. The powder X-ray diffraction diagram of the dried powder (FIG. 1) shows the sodium salt of crystalline zirconium phosphate [NaZr ₂ (P
O ₄ ) ₃ ].
The main peak at θ of 14 to 35 degrees was slightly shifted to a lower angle side, and did not contain crystalline impurities. As a result of the particle size distribution measurement, the white powder obtained above had an average particle diameter and a maximum diameter of 0.5 μm and 2.1 μm, respectively, and consisted of uniform and fine particles. Example 2 The charged amount of ammonium chloride was 21.7 g (0.40 m
ol), and the reaction was carried out in the same manner as in Example 1 except that the charged amount of the 20% aqueous sodium hydroxide solution was 126 g (0.63 mol) [equivalent ratio (A) = 1.6].
41.3 g of a white powder were obtained. As a result of chemical composition analysis of the white powder, the equivalent ratio of sodium ion to ammonium ion was about 0.8: 9.2. As a result of the particle size distribution measurement, the white powder obtained above had an average particle size of 0.5 μm and consisted of fine particles. Comparative Example 1 A white powder was obtained in the same manner as in Example 1, except that the aqueous solution (a) and the raw material liquid (B) were mixed and then oxalic acid was added. The obtained dry powder was obtained from an X-ray diffraction diagram (FIG. 2) showing exactly the same X-ray diffraction peaks as cubic (languine-stone) ammonium zirconium phosphate [NH ₄ Zr ₂ (PO ₄ ) ₃ ]. As can be seen, the compound was not a compound having an ammonium ion and an alkali metal ion. Comparative Example 2 In Example 1, 39.2 g of an 85% phosphoric acid aqueous solution was used.
The same operation was performed except that [0.34 mol, equivalent ratio (B) = 0.59] was used to obtain 65 g of a white powder. The X-ray diffraction pattern (FIG. 3) of the obtained dry powder does not show a pattern peculiar to the compound of the present invention, and is similar to that of the layered zirconium phosphate compound [NH ₄ ZrH (PO ₄ ) ₂ ]. An X-ray diffraction peak was shown. Comparative Example 3 In Example 1, the reagent primary zirconium oxychloride 8
3.8 g [0.26 mol, equivalent ratio (B) = 0.87]
Was performed in the same manner except that 63.1 g of white powder was used.
Got. The obtained dry powder was analyzed by powder X-ray diffraction (FIG. 4).
As can be seen from the table, Langvain-type zirconium phosphate was contained as an impurity. Example 3 The same operation as in Example 1 was repeated except that the same molar number of zirconium sulfate was used instead of zirconium oxychloride, to obtain 41.3 g of a white powder. X of the obtained dry powder
The line diffraction pattern was the same as in Example 1. Example 4 142 g of a 20% aqueous potassium hydroxide solution (0.51 mol) was used in Example 1 instead of the 20% aqueous sodium hydroxide solution.
l) was added [equivalent ratio (A) = 3.6], and the same operation was carried out except that the pH was adjusted to 3, to obtain 41.5 g of a white powder. As a result of a chemical composition analysis of the white powder, the equivalent ratio of potassium ion to ammonium ion was 3: 7.
The powder X-ray diffraction pattern of the dried powder shows an X-ray diffraction pattern very similar to that of the crystalline sodium phosphate compound [NaZr ₂ (PO ₄ ) ₃ ]. It shifted to the lower angle side, and did not contain crystalline impurities. As a result of the particle size distribution measurement, the white powder obtained above had an average particle size and a maximum size of 0.5 μm each.
m, 2.0 μm and consisted of uniform and fine particles. According to the present invention, a highly crystalline C is obtained by a wet method.
It is possible to obtain PZ, and the reaction product obtained by the present invention has unique ion exchange characteristics and a uniform and fine particle size distribution, so that an aqueous solution, resin or paint, etc. Can be used.
Therefore, the present invention has an extremely large industrial value as a production method capable of easily obtaining fine powder CPZ having a function as an ion exchanger. C obtained by the present invention
PZ is particularly useful as a raw material compound for supporting antibacterial metal ions such as silver ions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an X-ray diffraction diagram of the dry powder obtained in Example 1. FIG. 2 is an X-ray diffraction diagram of the dry powder obtained in Comparative Example 1. The circles attached to the peaks in the figure indicate that the peaks are attributed to Langbine-type stone crystals. FIG. 3 is an X-ray diffraction diagram of the dry powder obtained in Comparative Example 2. The mark x attached to the peak in the figure indicates that the peak is attributed to zirconium phosphate having a layered structure. FIG. 4 is an X-ray diffraction diagram of the dry powder obtained in Comparative Example 3. The circles attached to the peaks in the figure indicate that the peaks are attributed to Langbine-type stone crystals.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-239313 (JP, A) JP-A-4-273803 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01B 25/37 B01J 39/12

Claims (1)

(1) A raw material liquid (A) comprising an aqueous solution containing zirconium and a carboxylic acid or a salt thereof, and a raw material liquid (B) comprising an aqueous solution containing phosphoric acid or a salt thereof. Mix,
A reaction slurry containing 0.61 equivalents to 0.8 equivalents of zirconium per equivalent of phosphate ions is produced, ammonium ions and alkali metal ions are contained in the reaction slurry, and alkali metal ions are added per equivalent of ammonium ions. A method for producing a crystalline zirconium phosphate represented by the following general formula [1], characterized in that a reaction slurry having a pH of not less than 1.4 and a pH of not more than 7 is heated at a temperature of not less than 80 ° C. . A _x NH _{4 (1-x)} Zr ₂ (PO ₄ ) ₃ .nH ₂ O [1] (where A represents an alkali metal ion and X represents 0 <X <
It is a number that satisfies 1 and n is a number that satisfies 0 ≦ n ≦ 2. )