JP2697040B2 - Ion exchange method for zeolite compacts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for ion-exchanging a zeolite compact used as an adsorbent-separating agent, an ion-exchanging agent catalyst or the like. More specifically, it is intended to provide a method for obtaining a molded article having a high gas exchange capacity and a high ion exchange rate by increasing the utilization rate of exchanged ions when performing ion exchange.

(Prior art) Zeolites are crystalline aluminosilicates having pores on the molecular order of several angstroms, and naturally occur naturally. At present, various types of zeolites, including those having a structure that does not exist in nature, are used. Synthesized artificially. Natural zeolites are usually obtained as crushed products, and synthetic zeolites are usually obtained as powder. Industrially, it is used as an ion exchange agent, adsorption / separation agent, catalyst, etc., but it is rarely used as a crushed product or powder in any case. Most commonly, it is used as a molded article having a certain strength.

The ion exchange method of the zeolite molded article according to the present invention,
It can be applied to ion exchange of zeolite compacts such as A-type, faujasite-type and mordenite-type, but 5A-type by exchanging calcium ion of NaA-type zeolite compact, which is most commonly used as an adsorption separator. The case where zeolite is obtained will be specifically described below by way of example.

The 5A type zeolite molded body is usually manufactured as follows. First, the synthesized NaA-type zeolite powder is subjected to ion exchange in an aqueous solution of calcium chloride, and usually 67% or more of sodium ions are exchanged for calcium ions to obtain 5A type. After drying, a clay-based binder, an organic binder such as carboxymethylcellulose, and water are mixed and sufficiently kneaded as a binder, and then molded by a usual molding method such as extrusion molding. Next, calcination is performed at a temperature of 450 ° C. to 700 ° C. to produce a 5A-type zeolite compact having a certain strength. The 5A-type zeolite compact produced in this manner can be used as an adsorptive separating agent, for example, by selective adsorptive separation of n-paraffins from a hydrocarbon mixture, and n
-Used for separation of butylene, separation and concentration of oxygen from air, etc.

As the ion exchange method, there are known a method of performing the above-mentioned NaA-type zeolite powder and a method of performing the granulation and firing of the NaA-type zeolite powder using a binder. Ion exchange in the powder state is usually performed by a batch method, but the utilization rate of the exchanged ions is not very high, and in order to obtain a high exchange rate, it is necessary to repeat the ion exchange operation several times. is there. On the other hand, JP-A-55-104913 discloses that an agent ion-exchanged in a compact has a higher gas adsorption capacity than a granulated agent ion-exchanged in a powder.

In the case of performing ion exchange with a molded body, there is an advantage that not only a batch method but also a column method can be used as compared with the case of performing ion exchange with a powder, and the ion exchange can be performed continuously. The present invention relates to a method for ion-exchanging a molded article, and more rapidly than before, and
An object of the present invention is to provide a method for uniformly increasing the ion exchange rate in a molded article and increasing the utilization rate of exchanged ions.

(Problems to be Solved by the Invention) When performing ion exchange on a molded body, it is necessary to perform defoaming treatment before ion exchange. When the molded body is brought into contact with the ion exchange liquid, a large number of air bubbles come out of the molded body, so that the air bubbles stay between the molded bodies. Because the ion exchange liquid does not penetrate into the inside of the molded product sufficiently quickly, it takes a long time for ion exchange, or the ion exchange rate of the entire molded product is not uniform And it is difficult to increase the ion exchange rate of the adult.

As a method of the defoaming treatment, a solid-liquid ratio is reduced, and the exchange liquid and the molded body are sufficiently brought into contact with each other by stirring to remove the remaining air bubbles. There are disadvantages such as the molded article being broken.

(Means for Solving the Problems, Functions and Effects of the Invention) Bubbles that are generated when the zeolite molded body is brought into contact with the ion exchange liquid, that is, the gas is fine cells called micropores in so-called zeolite crystals in the zeolite molded body. It exists in pores called mesopores and macropores between pores and zeolite crystals. The present inventor has proposed a method for removing these gases.
As a result of intensive studies on the temperature, contact time, hydration method, etc. of the ion exchange liquid, a defoaming treatment method that is extremely effective when performing ion exchange on a molded article, that is, a method of contacting with a surfactant solution before ion exchange Was found.

 Hereinafter, the present invention will be described in detail.

The zeolite molded article used in the present invention may be a molded article made by a conventional technique, and it is desirable that the zeolite be sufficiently hydrated before being filled in an ion exchange column. The ion exchange method may be a batch method or a column method. However, when the ion exchange method is used, the defoaming effect is remarkably exhibited. Although the surfactant aqueous solution used as the defoaming liquid has its effect even at room temperature, the defoaming time can be shortened by further heating the same to the temperature of the ion exchange liquid. The surfactant used may be cationic, anionic, amphoteric or nonionic, and the concentration of the aqueous solution is 0.001 to
The range is preferably 5.0%, more preferably 0.01 to 1%. If the concentration is too low, defoaming will not be performed effectively.If the concentration is too high, the surfactant will adhere to the zeolite molded article after defoaming, and cleaning to remove the attached surfactant is necessary. Adversely affect ion exchange. In the case of defoaming with an aqueous solution of a surfactant, a large number of considerably small bubbles come out of the molded body as compared with the case of defoaming with water. On the other hand, when defoaming with water, agglomeration of air bubbles occurs, and when the air bubbles grow to a certain extent, phenomena such as the inability to move between molded bodies and stagnation between molded bodies occur. After the defoaming is completed, it is desirable to perform ion exchange subsequently. In the case of the fine batch method, the zeolite molded body is separated from the aqueous surfactant solution,
It is preferable to shorten the time for contact with the ion exchange liquid as much as possible. On the other hand, in the case of performing by the column method, the ion exchange liquid can be continuously circulated.

The ion exchange rate of the molded article obtained by the present invention is uniform throughout the molded article. It was also found that there was an effect that a high exchange rate was obtained. The effect of adding surfactant is
It is considered that the gas existing in the pores of the zeolite molded body easily exits the pores, and the generated bubbles are kept in a state of fine bubbles without aggregating.

(Examples) Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 100 parts by weight of a commercially available sodium A-type zeolite (Zeolam A4, manufactured by Tosoh Corporation) powder (about 100 mesh), 20 parts by weight of a clay-based binder, and 5 parts by weight of an organic-based binder were mixed.
Further, water was added and kneaded, and the mixture was extruded using a conventional extruder through a die having a diameter of 1.5 mm.
After drying the formed body at a temperature of 110 ° C in a ventilation dryer,
For 2 hours. After cooling, the product was hydrated until the water content became about 20% by weight.
Approximately 300 kg was packed in a column of m.

Tween 80 (manufactured by Kao Atlas Co., Ltd.), a 0.05% nonionic surfactant, which had been heated to 80 ° C., was passed through the column from the bottom to the top of the column at a flow rate of 25 / h for 2 hours (defoaming). Process). After the distribution of the Tween80 aqueous solution,
A 1N aqueous solution of calcium chloride was heated to 80 ° C. and passed from the lower part of the column to the upper part at a flow rate of 250 / h for 12 hours through this column (ion exchange step). Thereafter, the calcium chloride aqueous solution in the column was drained, and the column was washed with distilled water at room temperature (about 20 ° C.) for 2 hours at a flow rate of 2 m ³ / h from the lower part of the column. The calcium ion exchange rate of the molded body obtained in this manner was measured by atomic absorption spectroscopy, and as a result, the upper, middle, and lower portions of the column were 88.8, 8
They were 8.9 and 90.0%. The ion exchange rates of the eastern, western, southern, and northern walls at the top of the column were 88.5, 88.8, 88.7, and 88.9%, respectively. Further, a sample obtained by uniformly mixing the obtained zeolite molded product was −0 ° C., 700 torr.
When the nitrogen adsorption capacity at r was measured by the gravimetric method, 23.
It was 9 Ncc / g.

Example 2 Defoaming and ion exchange were performed in the same manner as in Example 1 except that the concentration of the aqueous solution of Tween 80 was changed to 0.5%. The calcium ion exchange rate of the obtained molded article was 88.9 at the center of each of the upper, middle and lower portions of the column,
89.1 and 89.0%. The ion exchange rates of the eastern, western, southern, and northern walls at the top of the column were 88.7, 88.9, 89.0, and 88.7%, respectively. Further, a sample obtained by uniformly mixing the obtained zeolite molded product was −10 ° C., 700 torr.
The nitrogen adsorption capacity at r was 23.7 Ncc / g.

Comparative Example 1 Ion exchange was performed in the same manner as in Example 1 except that the ion exchange step was performed for 14 hours without performing the defoaming step. The calcium ion exchange rate of the obtained molded body was 85.3 in the upper, middle, and lower central portions of the column, respectively.
79.2 and 80.1%. The ion exchange rates at the eastern, western, southern, and northern walls at the top of the column were 77.7, 84.1, 85.0, and 80.2%, respectively. Further, a sample obtained by uniformly mixing the obtained zeolite molded product was −10 ° C., 700 torr.
The nitrogen adsorption capacity at r was 20.9 Ncc / g.

Comparative Example 2 Ion exchange was performed in the same manner as in Example 1 except that the defoaming step was performed using only the aqueous solution and the ion exchange step was performed for 16 hours. The calcium ion exchange rates of the obtained molded articles were 87.4, 80.7, and 89.0% at the center of each of the upper, middle, and lower portions of the column. The ion exchange rates of the eastern, western, southern, and northern walls at the top of the column were 80.7, 84.7, 87.0, and 85.0%, respectively. Further, -10 of a sample in which the obtained zeolite molded body was uniformly mixed was used.
The nitrogen adsorption capacity at 700 ° C. and 700 torr was 21.7 Ncc / g.

Claims (1)

(57) [Claims] 1. A method for ion-exchanging a zeolite molded article, comprising: first exchanging a zeolite molded article which has been heat-treated in advance with an aqueous solution of a surfactant, followed by ion exchange.