JP2808033B2 - A method for ion exchange and stabilization of synthetic zeolites. - Google Patents

Description

The present invention relates to a method for ion-exchanging and stabilizing synthetic zeolites, and to ion-exchanged synthetic zeolites free from self-disintegration with water, in particular It relates to an antibacterial zeolite.

[Related Art] Zeolite has an intrinsic pore diameter, a surface electric field, an ion exchange ability, an adsorption separation ability, and the like, and attracts attention as an extremely useful functional material. In particular, synthetic zeolites have been widely used because homogeneous products characteristic of synthetic materials can be produced in large quantities and can be supplied stably.

Synthetic zeolites are generally produced by mixing and aging solutions of sodium silicate, sodium aluminate and sodium hydroxide, filtering the resulting gel, washing with water and drying.

Zeolites can also carry other metal ions by ion exchange, so that zeolites loaded with a particular metal ion exhibit not only the zeolite-specific functions but also the functions attributed to the metal ions. . For example, French patent application No. 1061158, Japanese Patent Publication No. 63-54013,
JP-A-63-260810 and JP-A-63-270764 describe antibacterial compositions containing zeolite ion-exchanged with antibacterial ions such as copper, zinc and silver. Further, a transition metal such as nickel can be carried on the zeolite to add a catalytic action.

[Problem to be Solved by the Invention] Conventionally, a commercially available synthetic zeolite is washed with water at a later stage of the production process, but when it is dispersed in water, the dispersion exhibits strong alkalinity.

As described in Examples below, a study was made on synthetic zeolites made by the present inventors and zeolite manufacturers in Japan and abroad.
After holding for a time, the pH becomes about 8-12, and about 10-30
The presence of aluminum in ppm was confirmed. Even if the synthetic zeolite is tested again after washing with a large amount of water again,
Again, the dispersion was found to exhibit strong alkalinity. Therefore, when the synthetic zeolite was neutralized with a dilute acid, separated, washed with water and dispersed in water, the dispersion was also alkaline. Therefore, a drop of 1N hydrochloric acid (0.03%) was added to a dispersion of synthetic zeolite (pH 11 of the dispersion) exhibiting strong alkalinity.
ml) was added dropwise, but the pH reached 11 after 24 hours. When 1N caustic soda is dropped on the zeolite dispersion, 24
After an hour, the pH also became 11.

On the other hand, when a certain natural zeolite is dispersed in water, the pH becomes 6.8.
And the aluminum concentration was below the detection limit (0.5 ppm). When 1N hydrochloric acid was added dropwise to the same zeolite dispersion, the pH immediately became 5.0 and was the same after 24 hours. On the other hand, when 1N caustic soda was added dropwise to the same zeolite dispersion, the pH immediately became 9.0 and after 24 hours. Was the same.

As described above, conventional synthetic zeolites exhibit remarkable alkalinity unlike natural zeolites, and even when the synthetic zeolite is washed or neutralized as usual, it still shows remarkable alkalinity. Such properties of the synthetic zeolite do not change even after ion exchange, and the ion-exchanged synthetic zeolite also exhibits remarkable alkalinity. As shown in Examples below, when the synthetic zeolite after the ion exchange was performed for 5 hours or more under acidic conditions was dispersed in water in the same manner as described above, the pH became about 10.

Such basicity may be a disadvantage when ion-exchanged zeolite is used as an antibacterial agent, an adsorbent, a catalyst, a carrier, a filler, and the like.

Accordingly, an object of the present invention is to provide an ion-exchanged synthetic zeolite in which the instability to water and moisture in the air is eliminated, and the dispersion does not exhibit alkalinity when dispersed in water.

[Means for Solving the Problems] The inventor of the present invention has proposed that by simultaneously immersing the synthetic zeolite until the pH becomes constant while maintaining the ion exchange solution containing the metal ions to be carried out acidic while simultaneously carrying out the ion exchange of the synthetic zeolite. It has been found that a desired stabilized and ion-exchanged synthetic zeolite can be obtained.

That is, the present invention provides a method for ion-exchanging a synthetic zeolite, in which a synthetic zeolite is immersed in an acidic aqueous liquid containing metal ions, and an acid is added so as to keep the pH of the immersion liquid at a predetermined value of about 7 or less, The immersion is continued until a substantially constant pH is maintained for at least one hour without any further acid addition, and then without washing the synthetic zeolite or under conditions where the pH of the wash does not substantially exceed about pH 6.5. And then drying by heating.

The present invention is also a synthetic zeolite stabilized and ion-exchanged by the above method.

Further, the present invention is a method for producing an antibacterial zeolite according to the above method, and an antibacterial zeolite thus produced.

Here, the immersion should be continued until the pH of the ion exchange solution becomes constant for a long time at 7 or less without adding an acid. Then, without washing or if washing, the pH of the washing solution is increased to 6.5 for a considerable time. It is an important requirement of the present invention to carry out washing under conditions that do not exceed the temperature and to heat and dry. Of course, simply performing washing and neutralization after ion exchange as in the past does not achieve the purpose, and even after performing ion exchange and immersion treatment as described above, washing with a large amount of water If the washing solution is heated and dried after the pH of the washing solution exceeds 6.5 (particularly after neutralization), the object of the present invention cannot be achieved. On the other hand, according to the present invention, after the ion exchange and immersion treatment, the product zeolite is washed without washing or under the condition that the pH of the washing liquid does not substantially exceed 6.5, and after heating and drying once, the stability of the product zeolite even after washing with water. Sex is not spoiled. Washing with water after heating and drying is particularly preferable when washing is not performed before heating and drying.

In the present invention, the synthetic zeolite includes all synthetic zeolites. Synthetic zeolites generally, based on the Al ₂ O ₃ is represented by _{xM 2 / n O · Al 2} O 3 · ySiO 2 · zH 2 O.
M is a monovalent or divalent metal, particularly an alkali metal such as sodium and potassium, but may be partially or entirely substituted with another metal or an ammonium ion. n is its valence. x, y and z are respectively
The coefficient of metal oxide, the coefficient of silicon dioxide, and the number of water of crystallization are shown. Various types of synthetic zeolites having different composition ratios, pore diameters, specific surface areas, and the like are known. As a typical synthetic zeolite, type A zeolite (SiO ₂ / Al ₂ O ₃ =
1.4 to 2.4), X-type zeolite _{(SiO 2 / Al 2 O 3} = 2~
3), Y-type zeolite _{(SiO 2 / Al 2 O 3} = 3~6), and the like mordenite _{(SiO 2 / Al 2 O 3} = 9~10).

An acidic aqueous liquid containing metal ions is an aqueous solution of a metal ion to be ion-exchanged and an inorganic acid and / or an organic acid. As the acid, for example, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and organic acids such as formic acid, acetic acid, oxalic acid, and tartaric acid can be used. As described above, various conventional acids can be used in the present invention, and among them, weak acids such as acetic acid, formic acid, tartaric acid, adipic acid and boric acid are preferred. Since weak acids act more slowly on zeolites than strong acids, the risk of adversely attacking zeolites in the time-consuming immersion treatment of the present invention is smaller. Inorganic acids and organic acids can be used in combination, and two or more kinds of inorganic acids or organic acids may be used as a mixture. The solvent is generally water and may contain small amounts of organic solvents and / or surfactants. Further, if necessary, inorganic salts or organic salts soluble in the acidic aqueous liquid can be added. The initial pH of the immersion liquid is below about 7, preferably 3.8 to 6.5, especially 4.
The pH is adjusted to 0 to 6.0, and the pH increases with the progress of the immersion treatment.

There is no particular limitation on metal ions, and iron, zinc, copper, tin,
Silver, vanadium, tungsten, nickel, barium,
Molybdenum, antimony, chromium, calcium, magnesium, manganese, lithium, aluminum, titanium,
Any ion-exchangeable metal ions such as gallium and germanium can be used. Therefore, as the metal ion to be supported on the zeolite, a preferable one may be selected according to the application. When an antibacterial zeolite is manufactured as an example, a metal zeolite having antibacterial properties, preferably silver, copper or zinc, is used.

In order to prepare a solution of metal ions, usually, a soluble salt, for example, a nitrate, a sulfate, a hydrochloride, or the like is prepared by dissolving it in an acidic aqueous solution, but other methods can be employed. For example, it may be prepared by directly dissolving a metal powder in an acidic aqueous liquid used for ion exchange.

The ion exchange / immersion treatment method is optional. Usually, zeolite or a zeolite dispersion, an acid or an acid solution, and a solution containing a metal ion to be supported are mixed, and the mixing order is not particularly limited. Hereinafter, the ion exchange / immersion treatment method of the present invention will be described by taking as an example an embodiment in which zeolite and then a metal ion-containing solution are added to an acid aqueous solution. An aqueous acid solution is placed in a container equipped with a stirrer, and the synthetic zeolite is gradually added and dispersed. At that time, the dispersion
Since the pH rises, an acid is appropriately added so as to maintain a predetermined pH of about 7 or less. The acid is added so as to maintain a predetermined pH while continuing to stir after dispersing all the zeolites. In parallel, a solution containing metal ions to be supported on the synthetic zeolite is gradually added. Stirring is continued even after all the metal ion-containing solutions have been added, and the ion exchange reaction is continued while adding an acid so as to maintain a predetermined pH of about 7 or less. The immersion treatment is continued until it is confirmed that the pH value is almost constant (± 0.5, preferably ± 0.3) even when no more acid is added. Generally, the immersion treatment does not require the addition of an acid.
1 hour or more, preferably 3 hours after the pH value becomes almost constant
Continue for more than an hour. The longer the treatment time after reaching a substantially constant pH, the better the stability of the product zeolite.
As an example of the processing conditions, the final concentration of the synthetic zeolite solid particles is 5 to 80% by weight, and 100 to 2000 rpm in the presence of about 1 to 10% of metal ions with respect to the synthetic zeolite.
At 10-80 ° C. under gentle stirring. The method and conditions of the ion exchange / immersion treatment are not limited to the above, and can be arbitrarily selected according to the type of synthetic zeolite, the type of metal ion, the purpose of use of the product zeolite, and the like. If the concentration of the synthetic zeolite is extremely low and the temperature is raised, the processing time can be shortened. The stirring speed is only slightly related to the processing time.

In addition to the above, when the zeolite is suspended in water in advance, and the acid and the metal salt aqueous solution are added little by little (the order of addition is not particularly limited), and the treatment of the present invention is performed,
The treatment pH, time and the like are the same as above.

Further, the treatment of the present invention can also be performed as the final step of the synthetic zeolite production process. That is, by separating the slurry after reaction containing a zeolite gel formed from an aqueous solution of sodium silicate, sodium aluminate and caustic soda, and treating the generated zeolite with an acid and metal salt solution, the above-described stabilization and ionization are achieved. Can be exchanged. Preferably, after the conventional step of separating zeolite from the slurry and washing with water is performed, the treatment of the present invention is performed again using the zeolite as a slurry.

If the synthetic zeolite contains impurities, wash it with water beforehand.
It is preferable to use a synthetic zeolite washed with hot water or an aqueous solution containing some acid.

What is important in the ion exchange and immersion treatment is that the treatment is continued until the liquid pH becomes substantially constant for at least one hour, preferably at least three hours, without additional acid addition. Depending on the type and production method of the synthetic zeolite,
It may not be constant for a predetermined time at an arbitrary pH value. In such a case, if the immersion treatment is performed by changing the intended pH value in various ways (generally on the more acidic side), a pH value that can achieve a constant pH without adding an acid is found.

After performing the ion exchange / immersion treatment for a sufficient time as described above, the synthetic zeolite is usually separated from the liquid. Separation can be performed by any method such as filtration and decantation.

The separated zeolite is subjected to heat drying without washing. Alternatively, optionally, washing can be performed under conditions where the pH of the washing solution does not substantially exceed 6.5. What is important in the washing operation is that washing is performed under conditions where the pH of the washing solution does not substantially exceed 6.5. Here, “the pH does not substantially exceed 6.5” means that the pH of the washing solution becomes 6.5 or less at the end of washing, and the pH of the washing solution is short.
Even if it exceeds 6.5, the stabilized synthetic zeolite aimed at by the present invention can be obtained. An acidic aqueous liquid can be used for the washing operation. As the acid, any acid that can be used for the immersion treatment can be used. The pH of the acidic aqueous liquid is preferably close to or lower than the pH at the time of immersion, but may be higher. It can be washed with a small amount of water. Depending on the separation method from the PH and the immersion liquid during the immersion treatment (for example, when the immersion treatment is performed at a low pH, or when the zeolite is separated from the immersion liquid by decantation), Significant acid remains on the zeolite. Therefore, even if a relatively small amount of water is used for the washing operation, the pH of the washing solution becomes 6.5 or less at the end of the washing, and the object of the present invention can be achieved. The washing operation itself can be performed by various conventional methods. For example, put the separated synthetic zeolite in a container with a stirrer,
Add a washing solution, stir and wash. Alternatively, washing is performed by pouring a washing solution into the zeolite in the separation device. The washing operation is usually performed within 30 minutes at room temperature using a washing solution having a volume of about 0.5 to 100 times the amount of zeolite, but the washing treatment can be performed under other conditions. By such a washing operation, the quality of the product is improved, such as removal of impurities generated from the zeolite during the ion exchange and immersion treatment and metal salts remaining without ion exchange.

Next, the obtained synthetic zeolite is dried by heating. Usually, it is carried out at 100 ° C. or more, preferably 120 ° C. or more, particularly 130 ° C. or more, for 1 hour or more, preferably 3 hours or more under normal pressure and, if desired, under reduced pressure. Such heat drying usually causes the attached acid to volatilize. Therefore, it is clear that the reason why the product zeolite of the present invention does not show strong basicity when dispersed in water is not due to the attached acid.
According to the present invention, the effects of the present invention can be achieved only after the ion exchange and immersion treatment, without washing, or by performing a specified washing operation and heating and drying. After ion-exchange and immersion treatment, washing with a large amount of water and drying by heating do not achieve the purpose. On the other hand, even if the product zeolite prepared according to the present invention is later washed with a large amount of water, the effect of the present invention is not lost.

A part or all of the above series of operations of ion exchange / acid immersion- (washing) -heating and drying may be repeated a plurality of times.

Although the present invention is not limited by a particular theory, it is considered that the surface of the synthetic zeolite is firstly ion-exchanged and simultaneously covered with a sol in the ion exchange / acid treatment according to the present invention. That is, while ion exchange of zeolite proceeds during ion exchange and immersion treatment, silicon and aluminum atomic groups (ionic groups) collapsed and dropped from defects in the zeolite crystal structure or zeolite raw material encapsulated inside the zeolite Reacts with the acid to form a sol on the zeolite surface. Subsequently, when the synthetic zeolite is heated and dried, it is considered that the sol is dehydrated and becomes a xerogel. Once a xerogel film is formed, it does not fall off by washing. However, the sol before heating and drying is weak, and will likely fall off when washed with water in a neutral or alkaline atmosphere. When the product zeolite of the present invention is dispersed in water, the xerogel membrane acts as a so-called semipermeable membrane, and is thought to prevent aluminum and silicon atomic groups and the like from coming out of the zeolite into the water. The product zeolite of the present invention is acidified water (hydrochloric acid, pH2
~ 3) and alkaline water (sodium hydroxide, pH10 ~ 1)
When dispersed in 1) (solid-liquid ratio 1:10), the dispersed water has the same pH, for example, pH 6.8, and the synthetic zeolite does not disintegrate, and aluminum ions are not detected in the dispersed water.

As described above, the product zeolite of the present invention is extremely stable in water. After the product zeolite of the present invention is dispersed in distilled water at a concentration of 50 g / l and kept at 20 to 25 ° C. for 24 hours, preferably 72 hours, the pH of the dispersed water is 5 to 7, preferably 6.0.
Stays in the range of ~ 6.8. The stability of the product zeolite of the present invention is also confirmed from the fact that aluminum ions are not detected in the dispersion water as described in the examples. In the case of a conventional synthetic zeolite, the pH of the dispersion water becomes strongly alkaline after 24 hours, and aluminum ions are detected.

JP-A-59-203723 discloses a modified zeolite in which a mineral component in seawater is supported on zeolite, and the equilibrium pH is adjusted to 10.5 or less, and the equilibrium pH is preferably 9.5 to 4.5. In the examples, those having an equilibrium pH of 6.5 are described. However, the equilibrium pH there is the pH value after only 30 minutes of a 5 g / 100 ml aqueous slurry. The inventors have found that equilibrium pH is not reached in 30 minutes. For example, when zeolite obtained by neutralizing a conventional synthetic zeolite with hydrochloric acid of pH 2.5 is dispersed in water, the pH of the dispersed water becomes 1
It is 6.5 after hours, but rises significantly to 8.9 after 24 hours. Therefore, the “equilibrium pH” zeolite in the above publication does not suggest the present invention. Further, the acid treatment of zeolite in the above publication is merely described as "neutralization treatment", and does not suggest a long-time treatment as in the method of the present invention. When a conventional synthetic zeolite is neutralized with an acid,
Although it is apparently neutralized promptly, even if it is dried without washing with water, it becomes alkaline when dispersed again in water.

The product zeolite of the present invention maintains stable neutralization or weak acidity, and is stable even when wet without increasing the pH. Therefore, it shows low irritation even when it comes into contact with body mucous membranes, skin, etc.,
Has no side effects. Therefore, it can be used for raw materials and materials related to medicine, medical care, cosmetics and food. Even when mixed and mixed with various organic materials and inorganic materials, since the structure is stable for a long period of time, it does not cause deterioration of the physical properties and properties of the material. Since the product zeolite of the present invention is stable and has a small amount of eluate, it is suitable for use in the purification of foods and pharmaceuticals. Further, as described in the examples, the zeolite supporting silver ions according to the present invention has an advantage that the zeolite supporting silver ions according to the conventional method has remarkably excellent light resistance.

The product zeolites of the present invention often have virtually the same function as conventional synthetic zeolites, for example, desiccants, adsorbents, ion exchange agents, various additives, or components such as catalysts and molecular sieves. It can be used as a granule for separation and water treatment, a carrier and the like. Products where the amount of supported metal ions is less than the ion exchange capacity of zeolite,
Products with almost the same ion exchange capacity are suitable for applications such as PSA and chromatography packing.

A case where the product zeolite of the present invention is mixed with an organic polymer and used will be particularly described. There is known a technique in which an antibacterial metal ion is supported on zeolite, mixed with a polymer, and molded (JP-A-59-133235).
Since the product zeolite of the present invention is neutral or slightly acidic, it does not cause deterioration of the polymer. The polymer is, for example, a synthetic or semi-synthetic organic polymer, particularly polyethylene, polypropylene, polystyrene, polyvinylidene chloride, polyamide, polyester, polyvinyl alcohol, polycarbonate, polyacetal, AB
Thermoplastic synthetic polymers such as S resin, acrylic resin, fluororesin, polyurethane elastomer, polyester elastomer, thermosetting synthetic polymers such as phenol resin, urea resin, melamine resin, unsaturated polyester resin, epoxy resin, urethane resin, Rayon, cupra,
Regenerated or semi-synthetic polymers such as acetate and triacetate are exemplified. By mixing the product zeolite into the polymer, it is possible to obtain a polymer molded article (including a coating and an adhesive) having the function of (modified) zeolite, such as adsorption, drying, and antibacterial properties.

[Examples] Hereinafter, the present invention will be further described with reference to examples.

In the following, the pH of water in which zeolite is dispersed (sometimes referred to as the pH of zeolite for simplicity) was measured as follows. Solid zeolite particles at normal pressure, 105 ° C
After drying for a period of time and cooling to room temperature, it was dispersed in distilled water at a concentration of 50 g / l, stirred at 20 to 25 ° C for 24 hours at 500 rpm, and measured at 20 ° C using a guaranteed electrode.

Aluminum elution was measured by stirring the 50 g / l dispersion at 20 to 25 ° C. for 24 hours at 500 rpm as described above, and then allowing it to stand for 72 hours, passing the liquid through a 0.45 micron membrane filter. The solution was determined by an atomic absorption spectrometry [AA-640-13, manufactured by Shimadzu Corporation]. The detection limit is 0.5 ppm.

Table 1 shows the synthetic zeolites used as raw materials in the examples. Each synthetic zeolite was pulverized and classified as necessary to obtain a desired particle size. The moisture content in the table is the moisture content of the product dried at 105 ° C.

Control Example The pH and the aluminum elution concentration of the above synthetic zeolites (1) to (8) were examined. The results are shown in Table 2.

Example 1 From the above eight kinds of synthetic zeolite particles, a product zeolite of the present invention was produced by the following method.

Ion-exchanged water 1 was placed in a 2 liter reactor equipped with a stirrer equipped with an acid addition device containing a 10% nitric acid aqueous solution. Adjust the initial pH of ion-exchanged water to 4, temperature 30 ° C, stirring speed 50
While stirring at 0 rpm, 100 g of synthetic zeolite solid particles were gradually added and dispersed. During this time, the pH of the dispersion in the reaction tank rose, so that acid was continuously added from the acid addition apparatus to keep the pH within 5.5 ± 0.3, and the pH in the reaction tank was continuously controlled. The addition of the synthetic zeolite particles was completed over about 20 minutes. Next, while controlling the pH in the same manner, 0.10
An aqueous solution in which 300 mol of copper nitrate trihydrate (Cu (NO ₃ ) ₂ .3H ₂ O) was dissolved in 300 ml of ion-exchanged water was added over about 20 minutes. After the addition of the aqueous solution of copper nitrate is completed,
The pH was controlled while adding acid for hours. Next, it was confirmed for 1 hour that the pH remained in the range of pH = 5.5 ± 0.3 without adding acid, and then the ion exchange / immersion treatment was completed. Next, after solid-liquid separation using a Buchner filter, the zeolite particles were dispersed in 3 l of an aqueous acetic acid solution having a pH of 5.0 ± 0.3, and washed at room temperature for 1 hour with stirring at 500 rpm. At this time, the pH of the washing solution is 5.
If it was likely to be greater than 0 + 0.3, 10% acetic acid was added to bring the pH within that range. After solid-liquid separation with a Buchner filter again, the zeolite was dried at 130 ° C. for 4 hours without washing with water to remove water, and then appropriately pulverized using a local mortar to obtain a product.

Incidentally, the ion exchange / immersion liquid at the end of the immersion treatment and the washing liquid after the end of the washing were all colorless and transparent, and the blue color peculiar to copper ions was not detected. This proved that most of the copper ions were supported on the synthetic zeolite by ion exchange.

The obtained zeolite of the present invention is dispersed in distilled water to adjust pH.
And the aluminum elution concentration were measured. The results are as shown in Table 3, and the stability to water was all very good.

Comparative Example 1 The same synthetic zeolite used in Example 1 was subjected to ordinary ion exchange treatment. The same reactor as in Example 1 was used.

Prior to ion exchange, the alkaline component of the synthetic zeolite was removed by washing with water. That is, 100 g of synthetic zeolite was stirred and dispersed in one ion-exchanged water, and solid-liquid separated using a Buchner filter, and then 3 l of ion-exchanged water was dispensed from the upper part of the filter. The pH of the filtrate was about 7.

The washed synthetic zeolite (100 g before washing) was put into a reaction tank, and ion-exchanged water 1 was added. Next, an aqueous solution in which 0.10 mol of copper nitrate trihydrate was dissolved in 300 ml of ion-exchanged water was added over about 20 minutes. After the addition of the aqueous copper nitrate solution was completed, stirring was continued at 30 ° C. for another 3 hours.

Next, after solid-liquid separation using a Buchner filtration device,
The zeolite particles were dispersed by stirring in 3 l of ion-exchanged water and washed. Solid-liquid separation was again performed using a Buchner filter, and ion-exchanged water 1 was poured from above the filter, washed thoroughly with water, and dried at 130 ° C. for 4 hours to remove water. Then, the product was pulverized appropriately using a mortar in a local government to obtain a product.

The immersion liquid and the zeolite washing liquid at the end of ion exchange were both colorless and transparent, indicating that most of the copper ions were supported in the synthetic zeolite.

The obtained zeolite particles were dispersed in distilled water, and the pH and the aluminum elution concentration were measured. The results are as shown in Table 4. The pH became alkaline, and aluminum ions were detected, even though the synthetic zeolite as the raw material had been washed with water in advance.

Example 2 A synthetic zeolite of the present invention was produced using ordinary synthetic zeolites (1) to (5). The same reactor as in Example 1 was used. However, the acid used was a 10% acetic acid aqueous solution.

1 ion-exchanged water was placed in a reaction vessel, the initial pH of the ion-exchanged water was adjusted to 5, and 100 g of synthetic zeolite particles were gradually added and dispersed while stirring at a temperature of 25 ° C. and a stirring speed of 500 rpm.

During this time, the pH of the dispersion in the reaction tank rises,
Acid is continuously added to keep the concentration within 0.3
H continued to control. The addition of the synthetic zeolite was completed in about 20 minutes. Subsequently, a solution prepared by dissolving 0.25 mol of silver nitrate and 0.10 mol of copper nitrate trihydrate in 300 ml of ion-exchanged water was added over about 20 minutes while controlling the pH as described above. After the addition of the aqueous silver nitrate / copper nitrate solution was completed, the pH was controlled while further adding an acid at 25 ° C. for 7 hours. Next, after confirming for 1 hour that the solution remained in the pH = 6.3 ± 0.3 region without adding acid, the treatment was terminated.

After solid-liquid separation using a Buchner filter, the zeolite particles were dispersed in 3 liters of acetic acid aqueous solution having a pH of 5.8 ± 0.3, and 50
Washing was performed for 1 hour at room temperature under stirring at 0 rpm. At this time,
If the pH was likely to be greater than 5.8 + 0.3, 10% acetic acid was added to bring the pH within that range. After solid-liquid separation again with a Buchner filter, the zeolite was washed without washing with water.
The product was dried at 0 ° C. for 4 hours to remove water, and then appropriately pulverized using a mortar.

The obtained product zeolite of the present invention was dispersed in distilled water, and the pH and the elution concentration of aluminum were measured. The results are as shown in Table 5, and the stability to water was extremely good.

Example 3 This example shows that the cleaning method after ion exchange and immersion of zeolite is important for the present invention. Synthetic zeolite particles (1) to (3) and (5)
A synthetic zeolite-Ag was prepared by the following method. The same reactor as in Example 1 was used.

100 g of synthetic zeolite is placed in a reaction tank and ion-exchanged water 1
Was added, and the mixture was stirred at a temperature of 30 ° C. and a stirring speed of 500 rpm for 10 minutes. An aqueous solution in which 0.25 mol of silver nitrate was dissolved in 300 ml of ion-exchanged water was added thereto over about 20 minutes while adding a 10% aqueous solution of nitric acid from an adding device to maintain the pH in the reaction vessel at 5.5 ± 0.3. After the addition of the aqueous silver nitrate solution was completed, an acid was further added at this temperature for 5 hours to maintain the above-mentioned pH.
Next, it was confirmed for 1 hour that the pH was maintained at 5.5 = 0.3 without adding acid, and then solid-liquid separation was performed using a Buchner filter, and the zeolite was stirred in 3 l of an aqueous acetic acid solution at pH 5.0 ± 0.3.
Separated and washed for 30 minutes. At this time, the pH of the washing solution is 5.0+
If it is likely to be larger than 0.3, add 10% acetic acid and add p
H was within that range. After solid-liquid separation with a Buchner filter again, the zeolite was dried at 130 ° C. for 4 hours to remove water without washing with water, and then appropriately pulverized using a local mortar to obtain a product.

For comparison, the same operation as above was performed except that the zeolite after the ion exchange / immersion treatment was stirred and dispersed in 3.0 l of ion exchange water for 30 minutes (control A).

Further, the same treatment as in Comparative Example A was performed on the synthetic zeolite from which the alkali component was removed by washing with water in the same manner as in Comparative Example 1 (Control Example B).

The obtained synthetic zeolite-Ag of the present invention and Control Example A,
The pH and the elution concentration of aluminum were measured for the synthetic zeolite-Ag of B. The results were as shown in Table 6.

The zeolite-Ag of the present invention was an extremely stable product having a pH almost neutral and stable, no elution of aluminum, and no self-destruction.

The light fastness of the various synthetic zeolites-Ag obtained above was examined.

The light resistance test was performed by the following method with reference to JIS L-0842.

After drying each of the above-obtained synthetic zeolites-Ag at 105 ° C. for 2 hours, they were filled in an aluminum ring having an inner diameter of 45 mm, and a pressure of 10 tons was applied by a press device to prepare a test molded body. Then with a fade meter for 40 hours,
Irradiation with a carbon arc lamp was performed, and color change was determined using a colorimeter (TC-1 type, manufactured by Tokyo Denshoku Industries).

The results are shown in Table 7. It is clear that the synthetic zeolite-Ag of the present invention has excellent light fastness.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C01B 39/02 B01J 29/06 B01J 20/18

Claims (5)

(57) [Claims] 1. A method for ion-exchanging a synthetic zeolite, wherein the synthetic zeolite is immersed in an acidic aqueous liquid containing metal ions, and an acid is added so as to keep the pH of the immersion liquid at a predetermined value of about 7 or less; Almost constant without additional acid
dipping is continued until the pH lasts for at least one hour, and then heat drying after washing without washing the synthetic zeolite or under conditions where the pH of the washing solution does not substantially exceed about pH 6.5. how to. 2. The method according to claim 1, wherein the synthetic zeolite after immersion is washed with an acidic aqueous liquid having a pH of about 6.5 or less or a small amount of water. 3. The method according to claim 1, wherein the metal ions are ions of one or more metals selected from the group consisting of silver, copper and zinc. 4. An ion-exchanged synthetic zeolite produced by the method according to claim 1. 5. A method according to claim 3, wherein the method comprises:
Ion-exchanged synthetic zeolite.