JPS6261531B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a method for producing highly active and highly pure X-type zeolite. More specifically, X obtained by the known production method of the present invention
The present invention provides a method for producing highly purified type X zeolite, which has superior physical properties compared to type zeolite and particularly has high activity. X-type zeolite is generally 0.9±0.2M〓O・
Al ₂ O ₃・2.5±0.5SiO ₂・xH ₂ O (M is a metal atom, n
is the valence of the metal, x is the number of molecules of crystal water)
It is expressed by the chemical formula and has a similar structure to natural faujasite.
Conventionally, the following methods are known as synthesis methods. Using sodium silicate as the silica source and sodium aluminate as the alumina source as raw materials for the synthesis of X-type zeolite, 100%
Method for obtaining type X zeolite by holding at ℃ for 6 hours [Zeolite and its utilization, P119
(1967), Gihodo; GTKerr, J.Phys.Chem.
70 , 1047 (1966)]. A method of obtaining X-type zeolite crystals by using silicate minerals such as carrion and allofene as starting materials and heat-treating them with an alkali. A method for producing type X zeolite by hydrothermal synthesis using raw materials containing Na ₂ O, Al ₂ O ₃ and SiO ₂ (USP 2882244). However, the quality of type X zeolite obtained by these known methods cannot necessarily be said to be satisfactory depending on the field of use. For example, the particle size distribution of type
It shows a wide distribution such as μ, and has the disadvantage that the particle size is irregular. With such a particle size distribution, the reactivity upon activation is not uniform, leading to undesirable results in terms of reaction rate during gas adsorption or ion exchange reaction with metal ions in solution. Furthermore, the known
In the type zeolite synthesis method, impurities such as A type zeolite and P type zeolite are easily mixed into the X type zeolite crystal particles, and the conversion rate of aluminum silicate (amorphous) to X type crystals is not necessarily satisfactory. There was a problem that it was impossible to say. The present invention provides an excellent method for producing X-type zeolite that overcomes the drawbacks of such known production methods. The present inventor conducted a detailed analysis of the factors that influence the synthesis of type X zeolite, and
As a result of follow-up experiments, we finally determined the composition and concentration of the raw materials used, alkalinity, heating rate of the reaction mixture for crystallization, crystallization temperature and time, liquid temperature and stirring operation during slurry formation, etc. It has been found that this has a significant effect on the quality of the type X zeolite obtained. Furthermore, in addition to the above-mentioned factors, the present inventor has determined the conditions for producing a slurry of amorphous aluminum silicate (the first step of the present invention) and the aging conditions for homogenizing the slurry (the second step of the present invention). It has been found that this is an extremely important factor in obtaining X-type zeolite crystal particles having excellent physical properties. The present invention has been made based on these valuable findings.
The present invention will be explained in detail below. The method of the present invention uses (a) an alkali metal salt of aluminic acid, (b) an alkali metal salt of silicic acid, (c) an alkali metal hydroxide, and (d) water as raw materials, and the method comprises: A mixture was prepared using the following amounts: SiO ₂ /Al ₂ O ₃ molar ratio = 2.5 to 3.6 M ₂ O / Al ₂ O ₃ molar ratio = 3.6 to 6.5 (M represents an alkali metal). , when the alkalinity of the aqueous phase of the mixture is 1.3
The amount of the alkali metal hydroxide used was adjusted to ~2.9N, and the mixture was stirred at a temperature below 40°C to generate an amorphous aluminum silicate salt and form a slurry mixture. , the resulting slurry mixture is maintained at a temperature range of 10°C to 45°C under stirring for at least 1 hour, and then the slurry mixture is heated to a temperature range of 80°C to 105°C for at least 1 hour. The first feature of the present invention is that the amorphous aluminum silicate salt is crystallized by raising the temperature to a temperature of The point lies in the step (abbreviated as the first step) up to the production of an amorphous aluminum silicate salt in the method of the present invention. That is, in the first step, in order to obtain a slurry-like mixture by producing an amorphous aluminum silicate salt, in the present invention, (a) an alkali metal salt of aluminate (b) an alkali metal salt of silicate (c) an alkali Using metal hydroxide and (d) water as raw materials, molar ratio of SiO ₂ /Al ₂ O ₃ in this raw material = 2.5 to 3.6 M ₂ O / Al ₂ O ₃ molar ratio = 3.6 ~6.5 (M represents an alkali metal) to prepare the mixture, and the alkalinity of the aqueous phase of the mixture is from 1.3 to
The requirement is to adjust the amount of alkali metal hydroxide used above to 2.9N and to stir this mixture at a temperature below 40°C. Among the raw materials, the alkali metal salt of aluminate is prepared by using aluminum hydroxide as a starting material and forming the alkali metal salt of aluminate with the aluminum hydroxide, water, and alkali metal hydroxide. It may also be prepared by forming an aqueous solution. Therefore, in such a case, the alkali metal salt of aluminate in the representation (a) of the raw material of the present invention can be read as an aluminum hydroxide salt. The second feature of the present invention is a step (abbreviated as the second step) of maintaining the slurry mixture obtained in the first step in a temperature range of 10°C to 45°C to ripen the precipitate. . In this step, the above-mentioned slurry mixture is aged by maintaining it at a temperature range of 10° C. to 45° C. for at least 1 hour or more while stirring. A third feature of the present invention is that the liquid material containing the aluminum silicate salt slurry obtained in the second step is heated to a temperature of 80°C to 105°C for at least one hour to form an amorphous material. The step is to crystallize the aluminum silicate salt (abbreviated as the third step). Furthermore, the fourth feature of the present invention is a step (abbreviated as the fourth step) in which the product obtained in the third step is subsequently held in the temperature range of the third step for at least 2 hours or more. This step completes the final crystallization. To explain in more detail the characteristic requirements of the method of the present invention, in the present invention, aluminum hydroxide salt or a strong alkali such as sodium hydroxide is added to it as an alumina source for the synthesis of type X zeolite. Aluminum-containing compounds such as sodium aluminate obtained by this method are used. Further, as the silica source, water-soluble alkali metal silicate salts such as sodium silicate, water glass, etc. can be used. Moreover, sodium hydroxide is suitable as an alkali source. As mentioned above, the composition of these starting materials is Na ₂ O/
The molar ratio of Al ₂ O ₃ and SiO ₂ /Al ₂ O ₃ is 3.6 to 3.6, respectively.
6.5, it is necessary to maintain the alkalinity within the range of 2.5 to 3.6, and the alkalinity of the aqueous solution phase in the mixture consisting of solid phase and liquid phase containing the above raw material is 1.3 to 2.9N.
It is necessary to adjust so that These requirements have important effects on promoting the crystallization of type X zeolite, preventing contaminants from being mixed into the product, shortening the time required for producing type X zeolite, etc. In the alkalinity range below the lower limit of alkalinity, the alkalinity decreases and the crystallization of the amorphous silicate into X-type zeolite slows down. The above alkalinity can be easily measured by taking a certain amount of the reaction mother liquor, diluting it with an appropriate amount of water, adding a phenolphthalene indicator, and standardizing it using a standard hydrochloric acid solution. It can be carried out. In the first step of the present invention, it is necessary to maintain the raw material composition and alkalinity as described above and to form a precipitate of the hardly soluble aluminum silicate salt under forced stirring. The poorly soluble aluminum silicate slurry produced in this step is amorphous, and its particle size distribution and chemical composition are hardly constant. In addition, when the specific surface area is set to a small value, usually less than 100 m ² /g (based on anhydrous slurry), almost no zeolite formation is observed.
In order to homogenize the amorphous silicate slurry produced in this step and to minimize compositional fluctuations, the temperature should be below 40°C, preferably between 10°C and 40°C.
It is necessary to form a slurry under forced stirring at a relatively low temperature of °C. Next, in the aging step of the aluminum silicate slurry, which is the second step of the present invention, as described above, the product liquid is maintained at a temperature range of 10 DEG C. to 45 DEG C. and kept under stirring for 1 hour or more. This step is necessary to finally obtain high-quality X-type zeolite, and this step makes the particle size of the amorphous aluminum silicate slurry formed in the first step more uniform. , which has the advantage that it is homogenized and that local compositional fluctuations become extremely small as the aging time increases. The silicate slurry produced at the end of this process has a chemical composition similar to that of type The three-dimensional structure of quality is hardly visible. The specific surface area of the slurry particles obtained in this process is still small, usually less than 180 m ² /g, while the majority of the particles produced have a size of less than 10 microns. Such a size is preferable because it becomes a factor that promotes crystallization, which will be described later. As mentioned above, the first and second steps of the present invention are both carried out at relatively low temperatures with stirring, but by stirring at such temperatures, agglomeration (solid phenomenon) due to aggregation of the produced particles is prevented. This results in particles being more finely dispersed and more homogenized. The particles thus dispersed and homogenized have a favorable effect on crystallization into type X zeolite. Second
In the region where the slurry maturation temperature in the process is higher than the upper limit of 45℃, the slurry particle size tends to become excessive.
In that case, even if the third and fourth steps are subsequently carried out, the purity of the type X zeolite crystals finally obtained decreases, and the excellent type X zeolite of the present invention cannot be obtained. The third step of the present invention is to heat the aged aluminum silicate slurry-containing liquid.
This is the process of raising the temperature to the crystallization temperature to form zeolite. In this step, it is necessary to take at least one hour to raise the temperature from the liquid temperature in the preceding slurry aging step to a predetermined crystallization temperature. As a result, homogeneous X-type zeolite particles with extremely high purity are obtained through the final fourth step. At a shorter heating rate, the degree of contamination of A-type zeolite, P-type zeolite, amorphous substances, etc. into the final X-type zeolite increases, and the purity of the final X-type zeolite product tends to decrease. It will be done. Usually this heating step is for at least 1 hour, preferably 1 hour and 30 minutes to 3 hours.
In the fourth step of the present invention, the product obtained in the third step is heated at a temperature range of 80°C to 105°C for at least 2 hours.
This is done by holding it for more than an hour. As mentioned above, the formation of type X zeolite crystals depends on alkalinity, temperature, time, and other factors, but the present invention can be performed even if it takes 30 hours at a temperature below the above lower limit, for example, at a temperature of 60°C. It is not possible to produce high purity type X zeolites as obtained by the method. Also,
Since the mother liquor boils at temperatures above the above upper limit, crystallization at such high temperatures cannot achieve the object of the present invention. By the method of the present invention, type X zeolite with extremely high purity and excellent quality can be obtained, and the average particle size of the type X zeolite is within the range of 2 to 4 μ, is extremely homogeneous, and has high activity. The type X zeolite obtained by the method of the present invention exhibits superior performance in terms of gas adsorption ability and ion exchange reaction compared to commercially available type X zeolite. In a preferred embodiment of the method of the present invention,
A strongly alkaline sodium aluminate solution is injected at a constant rate into a solution containing sodium silicate and sodium hydroxide under forced stirring. An amorphous aluminum silicate slurry is produced with stirring in the temperature range. At this time, in the solid-liquid mixture obtained at the end of the above injection operation,
The molar ratios of _Na2O / _Al2O3 and _SiO2 / _Al2O3 are in the range of 3.6-6.5 and _{2.5-3.6 ,} respectively, and the alkalinity of the aqueous phase in the mixture is in the range of 1.3-2.9N. It is necessary to adjust the concentration to maintain it within the range. By employing such a raw material injection method, compositional fluctuations in the aluminum silicate slurry produced can be minimized, and a homogeneous slurry with relatively uniform particle sizes can be formed. By performing the method of adding raw materials as described above, it is possible to obtain the advantage that the subsequent maturing step of the slurry becomes easy and the required time is shortened.
In addition, if such slurry formation is performed,
As seen in the examples, the crystallization process to form zeolite has the advantage that favorable results can be obtained in a short period of time. Further, in a preferred embodiment of the present invention, when forming an amorphous aluminum silicate slurry, a sodium silicate solution is injected at a constant flow rate into a sodium aluminate solution containing a strong alkali under forced stirring. An amorphous aluminum silicate slurry is produced at a relatively low temperature of 40°C or lower, usually in a temperature range of 10°C to 40°C, with stirring. At this time, Na ₂ O / Al ₂ O ₃ in the mixture at the end of the injection operation
and the molar ratio of SiO ₂ /Al ₂ O ₃ is 3.6~
6.5, within the range of 2.5 to 3.6, and the alkalinity of the aqueous phase in the mixture must be maintained in the concentration range of 1.3 to 2.9N. After completing this slurry formation, it is possible to obtain a slurry of substantially the same quality as that obtained in the above-mentioned embodiment by sequentially carrying out the above-mentioned 2nd to 4th steps. Zeolites with favorable properties can also be obtained. Furthermore, in a preferred embodiment of the present invention, when forming the amorphous silicate slurry,
Unlike the slurry formation method in the embodiment described above, the sodium silicate solution and the sodium aluminate solution are prepared separately, and these two solutions are individually mixed with water or a strong alkali under forced stirring at a predetermined flow rate. The mixture of Na ₂ O / Al ₂ O ₃ and SiO ₂ /
A mainly amorphous aluminum silicate slurry is prepared such that the molar ratio of Al ₂ O ₃ is in the range of 3.6 to 6.5 and 2.5 to 3.6, respectively, and the alkalinity of the aqueous phase in the mixture is 1.3 to 2.9N. The formation is carried out at relatively low temperatures below 40°C, usually in the temperature range of 10°C to 40°C. Subsequently, by sequentially performing the second to fourth steps, a highly purified X-type zeolite with high activity can be obtained. The porous X-type zeolite obtained by the method of the present invention has an average particle size of 2 to 3 μm, and a specific surface area of at least 900 m ² /g. The static adsorption capacity for gases of type X zeolite obtained by the method of the present invention is significantly superior to that of the known commercial product (type
The ion exchange capacity and rate for Ca ²⁺ and Mg ²⁺ are also significantly superior to commercially available X-type zeolites. Examples of the present invention are listed below.
The present invention is not limited to these examples. Example 1 175 g of aluminum hydroxide salt was collected in a three-necked glass flask, and 240 ml of water and 275 g of sodium hydroxide were added thereto and dissolved by heating to prepare a sodium aluminate solution. To this solution, 710 g of sodium silicate solution and water were added, the total volume of the resulting mixture was maintained at 3.5, and aluminum silicate slurry was produced at around 30° C. under stirring at 1000 rpm. In this case the Na ₂ O/Al ₂ O ₃ molar ratio was kept at 4.4 and the SiO ₂ /Al ₂ O ₃ molar ratio at 3.3, while the alkalinity of the aqueous phase was kept at 1.9N. Next, the amorphous aluminum silicate slurry produced in the above process was maintained at a temperature range of 25° C. to 30° C. under stirring at 750 rpm for about 2 hours to perform a slurry aging step. Subsequently, the slurry-containing liquid was heated for 2 hours.
It took 20 minutes to raise the temperature to 96°C. After reaching the crystallization temperature of 96°C, the same temperature was maintained for 7 hours to complete the crystallization process of type X zeolite. The reaction product consisting of microcrystals of type X zeolite obtained by the above synthesis was filtered by centrifugation and then washed with warm water. Washing with warm water was continued until the pH of the washing solution reached 10-11. Next, the reaction product that had been washed with water was dried at 100°C to 110°C. The obtained type X zeolite has the following properties. Yield of X-type zeolite: 381g (dry product) Chemical composition of X-type zeolite powder (dry product powder): 0.94Na ₂ O・Al ₂ O ₃・2.3SiO ₂・xH ₂ O Average particle size: 3 to 4μ True specific gravity of type X zeolite (dried powder): 1.94 Specific surface area of type X zeolite powder (anhydrous): 921 m ² /g Example 2 490 g of aluminum hydroxide salt, 600 ml of water, and water 670 g of sodium oxide was added and dissolved by heating to prepare a sodium aluminate solution. Water was added to the above solution to dilute it and the final total volume was kept at 2.7 (Solution-1). On the other hand, 2.00 kg of sodium silicate solution was collected, and water and 100 g of sodium hydroxide were added to this to maintain the total volume at 7.3 (solution-2). The entire sodium silicate solution (solution-2) containing excess alkali prepared as described above was placed in a three-necked glass flask, and solution-1 was injected at a flow rate of 45 ml/min while stirring at 750 rpm. The injection operation was completed in 60 minutes. In this amorphous aluminum silicate slurry production process, the liquid temperature was maintained at 25°C. The molar ratio of Na ₂ O/Al ₂ O ₃ is 4.4 and
The SiO ₂ /Al ₂ O ₃ molar ratio was kept at 3.4. The alkalinity of the aqueous phase at the end of slurry formation was maintained at 1.92N. Next, the amorphous aluminum silicate slurry liquid produced in this process was heated at 300 rpm at a temperature of 25°C.
The slurry was aged for 1 hour and 10 minutes under stirring. Subsequently, the slurry-containing liquid was heated to 1
A step of raising the temperature to a crystallization temperature of 92° C. was carried out over a period of 40 minutes. After reaching the crystallization temperature of 92° C., the same temperature was maintained for 6 hours to complete the crystallization process of type X zeolite. The obtained fine crystals of type X zeolite were filtered by centrifugation and then washed with warm water.
The water washing is carried out until the pH of the washing solution becomes 10 to 11, and then the reaction product obtained by completing the water washing process is 100%
Dry at ~110°C. The obtained type X zeolite has the following properties. Yield of X-type zeolite: 1008g (dry powder) Chemical composition of X-type zeolite powder (dry powder): 0.98Na ₂ O・Al ₂ O ₃・2.48SiO ₂・xH ₂ O where x=5.45 Average particle diameter of type X zeolite (dried product): 2 to 3 μ True specific gravity of type X zeolite (dried powder): 1.97 Specific surface area of type X zeolite powder (anhydrous): 919 m ² /g Type X zeolite obtained in this example The particle size is 10 μ or less, and the average particle size is 2 as described above.
It was -3μ. The activity of such fine X-type zeolite is extremely high, as shown in the specific examples below.
It has been found that it has many superior properties compared to commercially available type X zeolite obtained by known methods. Example 3 1 water and 1.24 kg of sodium hydroxide were added to 790 g of aluminum hydroxide salt and dissolved by heating to prepare a sodium aluminate solution. Next, add water to dilute this solution to make a final total volume of 10.6
I kept it. (Solution-1). On the other hand, sodium silicate solution
Collect 3.22Kg and dilute it with water to make up the entire volume.
5.3 (Solution-2). The entire solution-1 was collected in a three-necked glass flask, which was kept under stirring at 700 rpm. The solution-2 was injected into the solution-1 under such stirring at a flow rate of 66 ml/min. This injection was completed in approximately 80 minutes. In this process of producing amorphous aluminum silicate slurry, the liquid temperature is between 25°C and 27°C.
It was kept at ℃. In this case the Na ₂ O/Al ₂ O ₃ molar ratio was kept at 4.4 and the SiO ₂ /Al ₂ O ₃ molar ratio at 3.4. The alkalinity of the aqueous phase at the end of slurry formation was maintained at 1.85N. Next, the amorphous aluminum silicate slurry liquid produced in this process was heated to 25°C.
The slurry was aged at a temperature of 27°C for 2 hours with stirring at 300 rpm. Subsequently, the slurry-containing liquid was heated to a crystallization temperature of 97° C. over a period of 1 hour and 30 minutes. After reaching the crystallization temperature of 97°C, the same temperature was maintained for 5 hours to complete the crystallization process of type X zeolite. The resulting fine reaction product of type X zeolite was filtered by centrifugation and washed with hot water. This hot water washing was continued until the pH of the washing solution reached 10-11. The reaction product after this water washing step was dried at 100°C to 110°C. Yield of X-type zeolite: 1620g (dry powder) Chemical composition of X-type zeolite powder (dry powder): 0.98Na ₂ O・Al ₂ O ₃・2.46SiO ₂・xH ₂ O Average particle diameter: 2 to 3 μ True specific gravity of X-type zeolite (dry powder): 1.96 Specific surface area of X-type zeolite powder (anhydrous): 935 m ² /g At the end of the aging process of the aluminum silicate slurry of this example , a small amount of the slurry was taken and tested for physical properties. The specific surface area of the particles in this slurry was measured and found to be 157 m ² /g. This shows that at this stage, the product is mostly amorphous silicate, and crystallization into zeolite is almost negligible. In addition, this slurry is 0.97Na ₂ O・Al ₂ O ₃・2.63SiO ₂・xH ₂ O
In addition to showing the chemical composition of the substance, it was also confirmed that it was dispersed in extremely fine particles. In the final crystallization step of this example, a solid sample was collected 2 hours after the temperature was raised to 97°C, and as a result of electron microscopy and X-ray diffraction, it was found that most of the It was confirmed that aluminum silicate was crystallized into X-type zeolite. Example 4 To 1.22 kg of aluminum hydroxide, 1.7 kg of water and 1.9 kg of sodium hydroxide were added and dissolved by heating to prepare a sodium aluminate solution. The above solution was diluted by adding water to keep the final total volume at 6.6 (Solution-1). On the other hand, 5.0 kg of sodium silicate solution was collected and diluted with water to keep the total volume at 8.1 (solution-2). Further, 360 g of sodium hydroxide was dissolved in water to maintain a total volume of 15 (Solution-3). The entire amount of Solution-3 was put into a stainless steel reaction tank, which was kept under stirring at 650 rpm, and Solution-1 and Solution-2 were individually injected into this at different constant flow rates. That is, solution-1 is 94ml/min,
Solution-2 was injected into the reaction tank at a flow rate of 116 ml/min. Injection of both solutions was completed in about 70 minutes. In the step of producing this amorphous aluminum silicate slurry, the liquid temperature was maintained at 25°C to 28°C. At that time, the molar ratio of Na ₂ O / Al ₂ O ₃ was 5.04, and
The SiO ₂ /Al ₂ O ₃ molar ratio was kept at 3.36. Furthermore, the alkalinity of the aqueous solution phase at the end of slurry formation is
It was kept at 1.88N. The thus obtained amorphous aluminum silicate slurry was maintained at a temperature of 25° C. to 28° C. with stirring at 250 rpm for 2 hours and 30 minutes to age the slurry. Subsequently, the slurry-containing liquid was heated, and the temperature was raised to a crystallization temperature range of 94°C to 95°C over a period of 2 hours. Then, the obtained product is
The X-type zeolite was crystallized by maintaining the temperature in the above crystallization region for 5 hours. The obtained fine crystals of type X zeolite were filtered by centrifugation in the same manner as in the above examples, and then washed with hot water. The product was washed with water until the pH of the washing solution reached 10-11.
After washing with water, the X-type zeolite product will be at a temperature of 100℃ to 110℃.
dried in Yield of X-type zeolite: 2.48Kg (dry powder) Chemical composition of X-type zeolite (dry powder): 1.03Na ₂ O・Al ₂ O ₃・2.40SiO ₂・xH ₂ O Average particle size: 1.5 to 2.5μ True specific gravity of type X zeolite (dried powder): 1.93 ^Specific surface area of type It was observed that most of the aluminum silicate had been crystallized into extremely fine X-type zeolite over time. The purity of the X-type zeolite obtained in this example was extremely high, and the activity was also found to be superior to commercially available X-type zeolite adsorbents, as shown in specific examples below. The type X zeolite obtained by the method of the present invention is
As mentioned above, it is composed of fine crystal grains with a uniform grain shape, and its purity is significantly higher than that of X-type zeolite obtained by other known production methods. The average particle diameter of the X-type zeolite obtained in one embodiment of the present invention is 3 to 4 μ in Example 1, and 2 to 3 μ in Examples 2 and 3, and in a more preferred embodiment of the present invention. According to embodiments, it is possible to produce type X zeolites with even smaller average particle sizes. That is, the average particle diameter of the X-type zeolite obtained in Example 4 is 1.5 to 2.5.
μ, and its activity is also extremely excellent. The X-type zeolite obtained by the method of the present invention is composed of extremely fine crystal particles, has a high specific surface area value as described in the examples, and has extremely high activity, so it has a high adsorption capacity for gases. Its adsorption rate and desorption rate are also extremely superior compared to X-type zeolite adsorbents obtained by known methods. Table 1 shows the water adsorption performance of type X zeolite obtained by the method of the present invention. Example 1
It can be seen that the moisture adsorption performance of the X-type zeolite obtained in 4 to 4 is significantly superior to that of the commercially available X-type zeolite (MS-13X). The temperature in parentheses in the table indicates that of the crystallization step, and the time indicates the crystallization time. Note that the * mark indicates the result of collecting a sample of the solid phase during the crystallization process and measuring its water adsorption capacity. Looking at the results in Table 1, it is expected that the X-type zeolite obtained by the method of the present invention will be more effective in the field of dehumidification than commercially available X-type zeolite adsorbents.

【table】

[Table] Table 2 shows the nitrogen gas adsorption capacity of the X-type zeolite obtained by the method of the present invention. The values in parentheses in the table indicate the crystallization temperature and time in the described examples. Table 2 shows that the type X zeolite obtained by the method of the present invention has a higher adsorption capacity than commercially available products. (Nitrogen gas adsorption amount (25℃) for commercially available MS-13X is determined by adsorption pressure of 500, 600,
At 740 mmHg, they are about 4.6, 5.4, and 6.6 ml/g adsorbent (NTP), respectively. )

[Table] The carbon dioxide adsorption capacity of type X zeolite obtained by the method of the present invention is shown, for example, as follows (25
℃).

[Table] This value shows that the adsorption capacity of type X zeolite obtained by the method of the present invention is significantly larger than that of commercially available products. (For example, CO ₂ − of commercially available MS-13X
The adsorption amount (25℃) is determined by adsorption pressure of 160, 320, 480,
73, 84, 89 at 600 and 720 mmHg, respectively.
93, 95ml/g adsorbent (NTP)). In the above gas adsorption test, the dry powder of type X zeolite obtained by the method of the present invention was
After activation at °C, this was further heated under reduced pressure to reactivate it and then used. The fine X-type crystal particles obtained by the method of the present invention have a high degree of activity and have the excellent property that the ion exchange reaction between the coexisting metal ions and the sodium ions of the zeolite phase takes place quickly even in an aqueous solution. As an example, X obtained in one embodiment of the present invention
type zeolite fine particles (chemical composition: 1.09Na ₂ O・
We present data obtained on ion exchange between Al ₂ O ₃ 2.34SiO ₂・xH ₂ O) and Ca ²⁺ in water.

[Table] As shown in this data, the Ca-binding capacity was 141 after 10 minutes (this is the theoretical value).
Furthermore, the 30-minute value was 146 (this corresponds to 78.8% of the theoretical value), and it was confirmed that the Ca-binding capacity had reached more than 80% of the theoretical value after 2 hours. Ta. In contrast, the Ca-bond value (CaOmg/
g-X type zeolite (anhydrous standard)) was 65 (10 minute value) and 97 (30 minute value). Note that this measurement of calcium binding ability was performed by the same method as the measurement of calcium binding ability of zeolite for detergent builder. It has been confirmed that the fine, highly pure X-type zeolite (Na-type) obtained by the method of the present invention has a remarkable effect on capturing divalent metal ions such as Ca ²⁺ dissolved in water. .

Claims (1)

[Scope of Claims] 1 (a) an alkali metal salt of aluminate, (b) an alkali metal salt of silicic acid, (c) an alkali metal hydroxide, and (d) water as a raw material, and this raw material is added to the raw material. molar ratio of SiO ₂ /Al ₂ O ₃ = 2.5 to 3.6 molar ratio of M ₂ O / Al ₂ O ₃ = 3.6 to 6.5 (M represents an alkali metal) to prepare a mixture thereof. In this case, the alkalinity of the aqueous phase of the mixture is 1.3.
The amount of the alkali metal hydroxide used was adjusted to ~2.9N, and the mixture was stirred at a temperature below 40°C to generate an amorphous aluminum silicate salt and form a slurry mixture. , the resulting slurry mixture is maintained at a temperature range of 10°C to 45°C under stirring for at least 1 hour, and then the slurry mixture is heated to a temperature range of 80°C to 105°C for at least 1 hour. ℃ to crystallize the amorphous aluminum silicate salt, and then maintain the temperature at the above temperature for at least 2 hours to produce a highly active, high purity X-type zeolite. how to. 2. The mixture of raw materials is prepared by adding together a strongly alkaline sodium aluminate solution obtained from aluminum hydroxide, water and sodium hydroxide, and an aqueous sodium silicate solution. the method of. 3. Adding the slurry mixture described above to an aqueous solution containing sodium silicate and sodium hydroxide;
The method according to claim 1, which is carried out by injecting a strongly alkaline aqueous sodium aluminate solution at a constant rate while stirring. 4. The slurry mixture is formed by injecting an aqueous solution containing sodium silicate and sodium hydroxide into a strongly alkaline aqueous sodium aluminate solution at a constant rate while stirring. the method of. 5 The above slurry mixture is formed by injecting separately prepared strongly alkaline sodium aluminate aqueous solution and aqueous solution containing sodium silicate and sodium hydroxide into water or sodium hydroxide aqueous solution at a constant rate while stirring. 2. The method according to claim 1, wherein the injection of the entire amount of both liquids is completed within the same period of time.