JPH11246214A - A-type zeolite bead compact and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a bead compact having high absorptivity and excellent strength property by constituting the compact consisting of a A-zeolite powder and a fibrous one-dimensional structure clay binder having a specified value or larger pore volume and pore surface area. SOLUTION: This compact has >=0.25 cc/g pore volume and >=20 m<2> /g pore surface area. This A-type zeolite is preferably a synthetic Na-type zeolite. As for a fibrous one-dimentional structure clay binder, the binder contains sepiolite-type clay or attapulgite-type clay and is preferably in an acicular crystal state. The A-zeolite powder is mixed and kneaded with the clay binder of a fibrous one-dimensional structure such as the sepiolite-type or attapulgite- type clay by 15 to 25 pts.wt. to 100 pts.wt. of the zeolite powder based on its anhydride and water, to become 0.8 to 1.0 kg/1 bulk density. Then, the kneaded material is formed into beads by a blade-stirrer-type rotary granulating machine. Thereafter, the beads are calcined, ion-exchanged and activated to obtain the bead compact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a molded article of A-type zeolite beads and a method for producing the same. More specifically, it is widely used as an adsorptive separation agent. By ion exchange of sodium ions into various ions according to the purpose by ion exchange method, for example, it is selected from a mixed gas containing nitrogen and oxygen as main components by an adsorption method. A-type zeolite which is useful in the fields of adsorbing nitrogen and separating and concentrating oxygen, and adsorbing and removing water in organic solvents, or adsorbing and removing water between double glasses whose market is expanding recently. The present invention relates to a bead molding and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a zeolite compact has been prepared by adding a zeolite powder, a clay-based binder, water and, depending on the purpose, an organic-based molding aid to a columnar (pellet), spherical (bead), granular, fine, or the like. It is formed into granules or the like. Further, as a special example, there is one using silica sol, alumina sol or the like as a binder.

[0003] In the case of an adsorbent produced using a binder having a different size from zeolite crystals, the key to exhibiting excellent adsorption performance is how to form pores in the obtained molded article. In general, the molded article is molded using a large amount of binder in order to increase the physical strength of the molded article.

[0004] However, usually used binders are extremely fine compared to zeolite crystals,
As the amount of the binder increases, the surface of the molded body is easily covered in proportion to the amount of the binder added, and the molded body is liable to be clogged up to the inside of the molded body. ) Is difficult to form, resulting in a compact having a small pore volume and a small pore surface area.

A bead-shaped compact is formed by a rolling granulation method utilizing centrifugal force. The bead-shaped compact generally has an onion shape, and almost no mesopore exists. Not. Such a problem in molding becomes more prominent when plate-like clay such as kaolin-type or bentonite-type clay is used as the binder.

As described above, when a gas is separated or concentrated using a small number of molded bodies even if there is no mesopore, the gas diffusion is difficult and the adsorption or desorption speed is reduced. It will be. For example, in a short cycle gas separation / concentration by a PSA (Pressure Swing Adsorption) method, there is a possibility that the inside of the compact is not effectively used.

[0007]

DISCLOSURE OF THE INVENTION The present invention overcomes the conventional problems in such a zeolite molded article, and has a large pore volume and a large pore surface area, and therefore has a large adsorption capacity and a high adsorption rate. The present invention is to provide an A-type zeolite bead molded article having excellent adsorption performance and excellent physical properties such as pressure resistance, and a production method capable of easily obtaining such an A-type zeolite bead molded article. It provides a method.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, water was added to the A-type zeolite powder and a fibrous one-dimensional clay binder, and these were added to the bulk. After kneading and kneading so that the density becomes 0.8 to 1.0 kg / liter, the mixture is formed into beads by tumbling granulation of a blade stirring type, so that the pore volume and the pore surface area are large, and the adsorption performance is improved. It has been found that an A-type zeolite bead molded product having high strength and excellent physical properties can be easily obtained, and the present invention has been completed.

Hereinafter, the present invention will be described in detail.

[0010] The A-type zeolite bead molded product of the present invention comprises:
A molded article comprising a synthetic sodium A-type zeolite powder and a clay binder having a fibrous one-dimensional structure, having a pore volume of 0.25 cc / g or more and a pore surface area of 2
0 m ² / g or more.

Here, the characteristics of the molded A-type zeolite beads of the present invention are such that the pore volume by mercury intrusion at a pressure of 30,000 psi is 0.25 cc / g or more and the pore surface area is 20 m ² / g or more. Is preferably
Further, the pore volume is preferably 0.28 cc / g or more. Within this range, the adsorption rate will be high, and in the range of pore diameter of 60 to 2,000,000 angstroms, 30% or more of the pore volume of the molded body will be mesopores, and excellent adsorption performance can be exhibited. Generally, the performance of the zeolite adsorbent used for separation and concentration depends on how quickly the adsorbed substance diffuses in the molded body. Therefore, the pore volume is large, and in particular, the mesopores are uniformly dispersed in the molded body, and the number of the mesopores is skillfully formed so as to increase as much as possible, thereby increasing the pore surface area and improving the diffusion rate. Thus, it becomes an excellent adsorbent in terms of the adsorption speed.

The shape of the A-type zeolite bead molded article of the present invention is not limited as long as it has the characteristics of the A-type zeolite bead molded article of the present invention such as a bead shape, such as a sphere or an ellipse. Never. Further, the size may be any size in accordance with the purpose of use in consideration of ease of molding and operability, and is usually 0.5 to 5 m.
A molded body having a diameter of about m is used.

The A-type zeolite powder used in the A-type zeolite bead compact of the present invention is preferably a synthetic product in consideration of purity, and preferably has sodium as an ion-exchange group. .

The fibrous one-dimensional clay binder used in the A-type zeolite bead molding of the present invention includes:
Including sepiolite-type clay and attapulgite-type clay,
The binder is present between the zeolite particles in the molded article, and is preferably a needle-shaped crystal in order to increase the pore surface area of the molded article. These clays are 1
Not only one kind but also two or more kinds may be mixed.

The composition ratio of the X-type zeolite and the clay binder in the X-type zeolite bead compact of the present invention is such that when the amount of the clay binder is large, the pore surface area is large and the strength is strong, and when the amount of the clay binder is small, In consideration of an increase in the pore volume, a zeolite having a ratio of about 15 to 25% by weight of the X-type zeolite is preferably used.

Next, a method for producing the molded A-type zeolite beads of the present invention will be described.

[0017] The production method is as follows: A-type zeolite powder and fibrous one-dimensional clay such as sepiolite-type or attapulgite-type clay of 15 to 25 parts by weight based on 100 parts by weight of the X-type zeolite powder on an anhydrous basis. Water is added to the binder and the mixture is kneaded and kneaded so as to have a bulk density of 0.8 to 1.0 kg / liter, and then formed into beads by tumbling granulation of a blade stirring type.

Here, sepiolite-type clay and attapulgite-type clay which are clay binders to be added are S
i, Al, Mg, and Fe are only slightly different in content, and are basically similar hydrous magnesium silicates having a fibrous primary structure. Have the same physical properties. Therefore,
In the following description, it is described as a clay binder without any particular limitation.

In the method for producing a zeolite bead compact of the present invention, a step of mixing and kneading a synthetic sodium A-type zeolite powder, a binder and water, a step of forming the kneaded product into beads, a step of drying and firing the compact. The method includes a step of performing ion exchange by contacting with a salt aqueous solution of potassium, calcium, or the like, and a step of firing and activating the molded body according to the steps and applications, which will be described below in order.

<Mixing and Kneading Step> The synthetic sodium A-type zeolite powder used in the zeolite bead compact of the present invention is preferably a known one, that is, one synthesized from sodium aluminate and sodium silicate.

The synthetic sodium A-type zeolite powder and the binder are kneaded and mixed so that they are all uniform while adjusting the water content, and then have a bulk density of 0.8 to 1.0 kg /.
Knead well to make up liters. When the bulk density of the mixture at the time of kneading and mixing is smaller than 0.8 kg / liter, the compaction is not sufficient, and pores of air bubbles exist between the particles of the mixture, so that granulation properties may be reduced.

The amount of the clay binder to be added is as follows:
In order to increase the physical strength of the molded body, maintain a higher adsorption capacity, and form a pore volume and a pore surface area,
A range of ２５25 parts by weight is preferred. When the amount exceeds 25 parts by weight, the adsorption capacity of the obtained molded body is reduced due to a relative decrease in the amount of zeolite, and when the amount is less than 15 parts by weight, the physical strength is remarkably reduced, making it difficult to withstand use as an adsorbent. Is not preferred.

The amount of water added for adjustment when mixing and kneading the zeolite powder and the clay binder depends on the properties of the raw material zeolite powder and the clay binder, and the ratio of these amounts. The amount to be added is preferably in the range of 60 to 65 parts by weight based on 100 parts by weight of the zeolite powder.

<Molding Step> The mixture having a bulk density of 0.8 to 1.0 kg / liter by sufficiently kneading is shaped into beads by stirring granulation using a blade stirring method. Strong shearing force is given by stirring blades compared to normal tumbling granulation, the added binder is uniformly dispersed and adheres to zeolite particles, and pores are formed by existing between zeolite particles Will be. The shape of the molded product is not particularly limited as long as it has the features of the zeolite bead molded product of the present invention, and may be spherical, elliptical, or the like, for example, having a size of 9 to 14 mesh. Can be obtained. However, when physical strength, particularly abrasion strength, is required in the use as an adsorbent, it is desirable that the bead molded body having a high sphericity is used. This is a method generally employed for sizing and smoothing the surface of a molded article.

It is easy to change the diameter of the beads to be formed and sized according to the intended use, and the size may be adjusted by classification using a sieve.

<Firing Step> The molded body thus formed is dried and fired, and the added clay binder is sintered. As a method for drying and firing, known methods can be used, and for example, a hot air dryer, a muffle furnace, a tubular furnace, or the like may be used. The firing may be performed at a temperature of 600 ° C. or higher, which is the sintering temperature of the clay binder, in order to stably maintain the shape of the obtained molded body, and a temperature condition of 600 to 650 ° C. is more preferable.

Further, the fired molded body can be cooled and humidified so that the water content becomes about 25%. The humidification operation is not an essential condition, but it is necessary to prevent breakage, such as cracking and peeling, of the molded body due to rapid heat generation due to moisture adsorption in contact with the ion exchange liquid during the next step of ion exchange treatment. It is an effective means to expel gas such as nitrogen adsorbed from the inside of the molded body and to make diffusion with the ion exchange liquid more efficient.

<Ion exchange step> The bead compact formed and baked in the above steps is brought into contact with an ion exchange liquid containing desired ions such as K and Ca at a predetermined temperature for ion exchange. The compound used for exchange with each ion is not particularly limited as long as it can be easily provided as an aqueous solution, but usually, an aqueous chloride solution is preferably used.

As a method of exchange, a batch contact method, a column flow method, or the like is usually used. In order to increase the ratio of exchanged ions to be contacted for efficient ion exchange or to reduce the amount of exchange liquid, a column flow method is used. The flow rate is preferably adjusted by using the above method, and a batch contact method is suitable for uniformly ion-exchanging the whole.

The exchange temperature at the time of performing these ion exchanges is determined in consideration of the ion exchange equilibrium reaching speed.
Usually, about 60 ° C. is preferably used. However,
For example, when the exchange is very difficult such as lithium ion, the exchange efficiency can be improved by increasing the exchange temperature. After the ion exchange in this manner, the molded body is taken out of the ion exchange aqueous solution, washed sufficiently with water or warm water, and usually dried at a temperature of about 80 to 100 ° C.

<Activation Step> By sintering and activating the compact obtained as described above, an adsorptive separating agent having excellent adsorption performance can be obtained. As the firing conditions, any purpose can be used as long as the purpose is to desorb the moisture in the molded body, and the molded body is thereby activated. In consideration of the heat resistance of the zeolite, it is desirable to quickly desorb water at a temperature as low as possible. Usually, it can be achieved under a temperature condition of 600 ° C. or less.
Considering the heat resistance of the type zeolite, it is desirable to treat at as low a temperature as possible, for example, by firing at 400 ° C. for about 1 hour.

The A-type zeolite beads obtained by the method of the present invention can selectively adsorb mixed gas, for example, nitrogen which is a main component in air by an adsorption method to separate and concentrate oxygen, Alternatively, it is useful in applications in the field of adsorbing and separating agents, such as adsorbing and removing moisture in gas or removing and adsorbing moisture between double glasses whose market is expanding recently.

The reason why the molded article of type A zeolite beads of the present invention can be obtained without impairing the pore structure essential for the adsorptive separation agent is that attapulgite-type clay or sepiolite-type clay having a fibrous one-dimensional structure is used as a binder. And by using a blade stirring granulator to apply a strong shear force to uniformly disperse these binders. That is, it is considered that countless pores can be formed between zeolite particles by adhering fine clay particles of 1 μm or less to the zeolite surface during molding. Therefore, the diffusion of the adsorbed gas and the like is accelerated, and for example, in the case of gas separation / concentration by the PSA method in which adsorption and regeneration are repeated in a fixed short cycle, the adsorbent becomes an excellent adsorbent effectively used even inside the compact.

It is considered that the further excellent pressure resistance or wear resistance is due to the fact that the uniformly mixed and kneaded clay binder is strongly sintered by firing.

However, such a presumption does not restrict the present invention at all.

[0036]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Each evaluation was carried out by the following methods: 1) Pore volume, surface area The fired and activated bead compact was placed on a mercury intrusion porosimeter (Micromeritics, Model: Poisizer)
9310) in a pressure range of 1 to 30,000 psi.

2) Pressure Resistance 25 pieces of the fired and activated bead moldings were measured with a hardness meter (manufactured by Kiya Seisakusho, Model: KHT-20).

The measurement is carried out by applying a load to the compact at a constant speed with an indenter having a diameter of 5 mm, and the weight when the compact is crushed is defined as the pressure resistance (kgf).

3) Abrasion rate The abrasion rate was calculated according to the particle strength measurement method described in JIS-K-1464 (1962 version). That is, the fired activated bead compact as a sample was allowed to stand in a desiccator at a temperature of 25 ° C. and a relative humidity of 80% for 16 hours or more until equilibrated. Then, about 70 g of the sample was 850 μm, 3
Using a sieve (Model: JIS Z-8801, manufactured by Tokyo Screen Co., Ltd., model: JIS Z-8801) with a set of 55 μm and a saucer, sieved for 3 minutes, and then sieved for 3 minutes to the above-mentioned sieve from which deposits and the like have been removed, and 50 g of a remaining sample is obtained. Is accurately weighed, 5 coins are set at the same time, and shaken for 15 minutes. The wear rate was calculated by the following equation (1) using the sample dropped on the pan as Xg.

Abrasion rate (% by weight) = (X / 50) × 100 (1) 4) Nitrogen adsorption amount It was measured using a Cahn electronic balance. Activation was performed at 350 ° C. for 2 hours at a degree of vacuum of 10 ⁻³ torr or less as pretreatment conditions. The adsorption temperature is kept at −10 ° C., and the adsorption capacity (unit:
Ncc / g) was calculated. The nitrogen adsorption amounts in Examples and Comparative Examples shown below are measured values at an equilibrium pressure of 700 torr.

5) Bulk density According to the method using an apparent density measuring device according to JIS-K-3362, the kneaded mixture was placed in a Vml polyethylene cup (W1), and a linear spatula was formed at the peak. After rubbing off, the weight (W2) of the cup containing the mixture was read to the nearest 0.1 g, and the bulk density was calculated by the following equation (2).

Bulk density (kg / liter) = (W 2 −W 1) / V (2) Example 1 100 weight of synthetic sodium A type zeolite powder (manufactured by Tosoh Corporation, SiO ₂ / Al ₂ O ₃ = 2.0) Attapulgite-type clay (15 parts by weight) was mixed and kneaded with a mixing muller granulator (manufactured by Shinto Kogyo Co., Ltd., model: MSG-05S), and finally water was added to 100 parts by weight of type A zeolite powder while appropriately adding water. The mixture was adjusted by adding 65 parts by weight of water, and then kneaded sufficiently. When the bulk density of the obtained kneaded product was measured by the above method, it was 0.85 kg / liter.

The kneaded product was stirred and granulated into beads having a diameter of 1.2 mm to 2.0 mm using a blade stirring granulator Henschel mixer (manufactured by Mitsui Mining Co., Ltd., model: FM / I-750). The granules were sized using a riser molding machine (Model: Q-1000, manufactured by Fuji Paudal Co., Ltd.) and then dried. Next, a muffle furnace (manufactured by Advantech, model: KM-6)
00) in an atmosphere of 600 ° C. under an air flow 2
After firing for a while to sinter the attapulgite type clay,
It was cooled in the air and humidified so that the water content became about 25%.

This compact was packed in a column of 70 mmφ × 700 mm (length), and calcium chloride was previously charged at 1 mol / mol.
An aqueous solution adjusted to a concentration of 1 liter was flow-contacted at 80 ° C. to exchange calcium ions, washed sufficiently with water while filling the column, and then dried at 80 ° C. for 16 hours. Thereafter, activation treatment was performed at 500 ° C. for 1 hour in a tubular furnace (manufactured by Advantech) under air flow. The pore volume, surface area, compressive strength, abrasion rate, and nitrogen adsorption amount of the obtained A-type zeolite beads were measured by the above-described methods. Table 1 shows the results.

[0045]

[Table 1]

Examples 2 to 8 Example 1 was repeated except for the types and amounts of the clays shown in Table 1.
A type zeolite bead molded product was prepared in the same manner as described above. S of synthetic sodium A type zeolite powder used
The iO ₂ / Al ₂ O ₃ molar ratio was 2.0, and the bulk density of the obtained kneaded product was measured by the method described above.
The range was 5 to 0.89 kg / liter. Table 1 shows the results of the measurement of the pore volume, surface area, pressure resistance, abrasion rate, and nitrogen adsorption amount of the obtained A-type zeolite bead compact by the above-described methods.

Comparative Examples 1 to 6 A-type zeolite bead moldings were prepared in the same manner as in Example 1 except for the types and amounts of clays shown in Table 2. Of synthetic sodium A type zeolite powder used
The O ₂ / Al ₂ O ₃ molar ratio was 2.0, and the bulk density of the obtained kneaded product was measured by the method described above to be 0.85.
０．９0.92 kg / liter. A obtained
Table 2 shows the results of measurement of the pore volume, the pore surface area, and the amount of nitrogen adsorbed by the zeolite bead molded product by the above-described method.

[0048]

[Table 2]

Comparing the above Examples and Comparative Examples, it can be seen that the A-type zeolite bead molded product obtained has a higher pore volume and a higher pore surface area, and therefore has a superior nitrogen adsorption amount. I understand. In particular, when the same amount of the clay binder is used with respect to the A-type zeolite powder, the effect is increased.

[0050]

As is clear from the above description, the zeolite bead molded article of the present invention has a high adsorption capacity and an adsorption rate due to a large pore volume and a large pore surface area, and has an excellent performance. It is a molded article having strength properties. Further, according to the production method of the present invention, an A-type zeolite bead molded product can be easily obtained.

Claims (5)

[Claims] 1. A molded product comprising a zeolite A powder and a clay binder having a fibrous one-dimensional structure has a pore volume of 0.25 c.
An A-type zeolite bead having a c / g or more and a pore surface area of 20 m ² / g or more. 2. The A-type zeolite bead molding according to claim 1, wherein the fibrous one-dimensional clay is a sepiolite-type clay and / or an attapulgite-type clay. 3. The synthetic sodium A zeolite powder and the synthetic sodium A zeolite powder on an anhydrous basis.
Water is added to 15 to 25 parts by weight of a fibrous one-dimensional clay binder with respect to 0 parts by weight to obtain a bulk density of 0.8 to 1.
The method according to claim 1 or 2, wherein the mixture is kneaded and kneaded so as to have a volume of 0 kg / liter, and then formed into beads by tumbling granulation using a blade stirring method, and then fired, ion-exchanged and activated. 3. The method for producing an A-type zeolite bead molded product according to item 2. 4. The method for producing a molded A-type zeolite bead according to claim 3, wherein the fibrous one-dimensional clay is a sepiolite-type clay and / or an attapulgite-type clay. 5. The A-type zeolite beads according to claim 3, wherein the calcined compact is packed in a column, and a solution containing calcium ions is passed through the column to perform ion exchange. A method for producing a molded article.