JP2756568B2 - Method for producing A-type zeolite molded body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a zeolite molded article used as an adsorption / separation agent, an ion exchange agent, a catalyst, and the like. More specifically, the present invention relates to a method for producing an A-type zeolite molded article having a remarkably high adsorption capacity, a relatively high ion exchange rate and a relatively high strength, and significantly reducing ion exchange costs. It provides a method.

[Prior Art] In A-type zeolite, the pore diameter of zeolite is determined by the type of metal ion. For example, the pore diameter of sodium ion is about 4 Å, that of potassium ion is about 3 Å, that of calcium ion is about 5 Å, and the like. Becomes A type zeolite having a desired pore size can be obtained by ion exchange with an ion of Group I or Group II of the periodic table at an appropriate ion exchange rate. Zeolites with controlled pore sizes are used in a wide range of fields such as adsorption / separation agents and catalysts. For example, A-type zeolite which has been subjected to calcium ion exchange and whose pore size has been controlled to 5 angstroms has been widely used for separating oxygen and nitrogen gas in air by the PSA adsorption separation method. When a zeolite is used for these purposes, particularly for industrial use, it is almost always used as a molded product having a certain strength for packing in a column.

Conventionally, a zeolite molded body is first ion-exchanged with desired ions with zeolite crystal powder, a zeolite crystal powder with a controlled pore size is added in advance, a binder such as clay is added thereto, and then mixed and kneaded, and then the usual molding is performed. It is manufactured by molding using a machine. The amount of the binder is 20 parts by weight or more, preferably 25 parts by weight, per 100 parts by weight of the zeolite A crystal powder.
More than parts by weight are added. The thus formed zeolite molded body is subsequently fired at a high temperature. This calcination is performed at a temperature at which the zeolite crystals do not break and give sufficient strength to the molded body, specifically at 450 to 800 ° C.

On the other hand, JP-A-55-104913 discloses that A-type zeolite molded powder having both high adsorptivity and strength is produced by molding A-type zeolite crystal powder and subjecting the obtained molded body to ion exchange treatment. A way to do that has been proposed. However, the publication only discloses a method using 25 parts by weight of binder per 100 parts by weight of zeolite. That is, the amount of the binder used is not different from the method of ion exchange before the above-mentioned molding.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method in which a molded A-type zeolite having a larger adsorption capacity or the like cannot be produced without lowering the strength.

Conventionally, efforts have been made to reduce the binder content in order to produce a zeolite molded body having a larger adsorption capacity. However, it has been industrially very difficult to reduce the amount of the binder due to a decrease in strength and a decrease in moldability. Therefore, the A-type zeolite compact contains about 20 to 30 parts by weight of the binder based on 100 parts by weight of the zeolite crystal powder.

Means and Action for Solving the Problems The present inventors have formed a sodium A-type zeolite crystal powder and then performed an ion exchange method to obtain the powder.
15 parts by weight or less per 100 parts by weight, in a much smaller amount than the conventionally used amount, found that it is possible to produce a molded body having sufficient strength to be practically used, and reached the present invention. . Nevertheless, if the amount is too small, the strength of the obtained molded body is still insufficient, so it is necessary to use 5 parts by weight or less per 100 parts by weight of the powder.

That is, the gist of the present invention is that, when manufacturing an A-type zeolite molded body, after blending 5 to 15 parts by weight of a binder per 100 parts by weight of the sodium A-type zeolite crystal powder, molding, firing, The present invention relates to a method for producing an A-type zeolite molded body, which comprises performing ion exchange by contacting with a solution containing exchangeable metal ions. The details will be described below.

The sodium A-type zeolite crystal powder previously formed into a molded body in the present invention may be obtained by a known method for producing sodium A-type zeolite crystal powder. Sodium A
The zeolite crystal powder is mixed with 5 to 15 parts by weight of a binder, kneaded and molded. Examples of the binder include bentonite, diatomaceous earth, kaolin,
Inorganic binders such as plastic ball clay, bentonite clay and kaolin clay; or organic binders such as crystalline cellulose such as methylcellulose, carboxymethylcellulose and hydroxymethylcellulose and molasses are used alone or in combination. The shape of the molded body is granular,
Any of a pellet, a sphere, and the like may be used.

Next, the molded sodium A-type zeolite molded body is preferably dried at a low temperature of 100 to 200 ° C in order to prevent the molded bodies from adhering to each other.

The dried and shape-adjusted sodium A-type zeolite molded body is heated and calcined. The firing conditions are desirably as high as possible, for example, 400 ° C. or higher, within the range that does not change the zeolite crystal structure, in order to impart strength to the molded body.

This calcined sodium A-type zeolite molded body is
Ion exchange is performed by contact with a liquid containing a metal ion, usually a metal ion belonging to Group I or II of the Periodic Table. The ion exchange method includes a batch method (batch method), a column method, and the like, and any method can be adopted. In the present invention,
Since the ion exchange is performed after the molding, the ion exchange can be performed by the column method, and the ion exchange cost can be significantly reduced. According to the present invention, the ion exchange step of zeolite crystal powder is not required,
It is also possible to suppress a decrease in the yield due to erosion of the zeolite crystal powder during washing and the like, which further promotes the effect of reducing the production cost.

Hereinafter, a column method which is an ion exchange method selected for economy will be described as an example.

There is no limitation on the concentration of the salt solution used for ion exchange. However, in consideration of the productivity and the material of the device, a concentration in the range of 0.5 to 2.0 N is preferable. The flow rate of the solution has an appropriate flow rate range depending on the column shape and size. The flow direction of the salt solution is not particularly limited. However, for example, in the case of ion-exchanging a sodium A-type zeolite molded body with a potassium salt solution, a method of flowing the potassium salt solution from the bottom to the top of the tower is preferable. Is
A method of flowing a calcium salt solution or a lithium salt solution from the upper part of the tower to the lower part is preferable. Regarding the temperature, it is possible to carry out the reaction at room temperature, but heating to about 90 ° C. is effective for shortening the time to reach the ion exchange equilibrium, and also for reducing the time and the amount of the flowing liquid. It is effective.

The ion-exchanged A-type zeolite molded body is washed after extracting the liquid from the column or while directly replacing the liquid in the column with the washing liquid, or dried without washing. Drying is performed under conditions sufficient for removing attached moisture by ion exchange or washing. Although this operation is performed under relatively mild conditions, the operation of removing water adhering to the A-type zeolite molded product and the operation of removing water adsorbed by the A-type zeolite crystal may be performed separately. For example, 80 to 12
The heating is performed at a temperature of 300C to 800C in order to remove moisture adsorbed by the zeolite A crystals. If these operations are performed under reduced pressure, the temperature may be low and the time can be shortened. Also, by flowing dry air or the like, an effect equivalent to that of an operation under reduced pressure can be obtained.

[Effects of the Invention] In the method for producing a zeolite molded body of the present invention, the binder is produced without prematurely reducing the strength by forming sodium A-type zeolite crystal powder having relatively good moldability and good compatibility with the binder. Is reduced, resulting in increased adsorption capacity. By performing the ion exchange for the purpose of controlling the pore diameter after molding the sodium A-type zeolite crystal powder, the ion exchange by the flow method becomes possible, and it is possible to lower the A without increasing the production cost, and to increase the A of the adsorption capacity. Molded zeolite molded bodies can be manufactured.

EXAMPLES Example 1 100 parts by weight of a crystal powder (about 100 mesh) of a commercially available sodium A-type zeolite (Zeolam A4, manufactured by Tosoh Corporation) and 10 parts by weight of a domestic kaolin-based clay were mixed. Was added and kneaded, passed through a die having a hole diameter of 1.5 mm, and extruded to obtain a molded product having a length of about 5 to 15 mm. The molded product was left to dry at 110 ° C. for 12 hours in a ventilation dryer, and then fired in a furnace at 550 ° C. for 2 hours. Approximately 1.3 kg of the calcined molded body is packed into a packed tower of 65 mm in diameter and 800 mm in length, and 1N calcium chloride aqueous solution is heated to 70 ° C and flows downward from the top of the packed tower at a flow rate of 40 ml / min. Then, sodium ions in the sodium A-type zeolite molded body were ion-exchanged into calcium ions. After the ion exchange, the calcium chloride aqueous solution remaining in the packed tower was drained, and 13 distilled water was passed through to wash. This A-type zeolite molded body in a ventilation dryer
It was left to dry at 110 ° C. for 12 hours. As a result of measuring the ion exchange rate of the obtained A-type zeolite molded body by atomic absorption spectrometry, the upper, middle and lower parts of the packed tower were 88.
8, 87.7 and 88.0%. (Sample A) Example 2 About 1.3 kg of a sodium A-type zeolite molded body prepared in the same manner as in Example 1 was packed in a packed tower having a diameter of 65 mm and a length of 800 mm.
Fill, warm 1N calcium chloride aqueous solution to 70 ° C,
At a flow rate of 80 ml / min, the flow rate was from the upper side to the lower side of the packed tower, and the sodium ions in the molded sodium A-type zeolite were exchanged for calcium ions. After washing and drying in the same manner as in Example 1, the ion exchange rate was measured by atomic absorption spectroscopy. As a result, the values were 87.5, 89.5, and 88.9% at the upper, middle, and lower portions of the packed tower. (Sample B) Example 3 About 1.3 kg of a sodium A-type zeolite molded body prepared in the same manner as in Example 1 was packed in a packed tower having a diameter of 65 mm and a length of 800 mm.
Fill, warm 1N calcium chloride aqueous solution to 70 ° C,
It flowed downward from the top of the packed tower at a flow rate of 160 ml / min, and the sodium ions in the molded sodium A-type zeolite were exchanged for calcium ions. After washing and drying in the same manner as in Example 1, the ion exchange ratio was measured by atomic absorption spectroscopy. As a result, the ratio was 89.6, 89.4, and 89.3% at the upper, middle, and lower portions of the packed tower. (Sample C) Example 4 A sodium A-type zeolite molded article prepared in the same manner as in Example 1 was immersed in a 1N aqueous calcium chloride solution heated to 80 ° C. for about 4 hours, stirred, and stirred. The sodium ions in the molded body were ion-exchanged into calcium ions. After ion exchange, perform solid-liquid separation,
Washed with distilled water. The same ion exchange operation was performed three times in total. As a result of measuring the ion exchange rate by the atomic absorption spectrophotometry, it was 91.0%. (Sample D) Comparative Example 1 2 kg of a crystalline powder (about 100 mesh) of commercially available sodium A-type zeolite (Zeolam A4, manufactured by Tosoh Corporation) was heated to 80 ° C.
Was immersed in a warmed 1N aqueous solution of calcium chloride 28 for about 4 hours, stirred, and ion-exchanged sodium into calcium ions. After ion exchange, perform solid-liquid separation.
Washed with 10 distilled water. The same operation was performed three times in total. As a result of measuring the ion exchange rate by the atomic absorption spectrophotometry, it was 91.0%. 100 parts by weight of the A-type zeolite crystal powder ion-exchanged to the calcium type and 20 parts by weight of the clay-based binder used in Example 1 were mixed, kneaded by adding water, and passed through a die having a pore diameter of 1.5 mm. Extrusion molding was performed to obtain a molded product having a length of about 5 to 15 mm. The molded product was allowed to stand at 110 ° C. for 12 hours in a ventilation dryer, and then fired in a furnace at 550 ° C. for 2 hours. (Sample E) Comparative Example 2 100 parts by weight of A-type zeolite crystal powder subjected to calcium ion exchange in the same manner as in Comparative Example 1 and a viscosity-based binder 15
The mixture was mixed with water, kneaded by adding water, and extruded through a die having a hole diameter of 1.5 mm to obtain a molded product having a length of about 5 to 15 mm. The molded product was allowed to stand at 110 ° C. for 12 hours in a ventilation dryer, and then fired in a furnace at 550 ° C. for 2 hours. (Sample F) Comparative Example 3 100 parts by weight of A-type zeolite crystal powder subjected to calcium ion exchange in the same manner as in Comparative Example 1, and a clay-based binder 10
The parts by weight were mixed, water was added and kneaded, and the mixture was extruded through a die having a hole diameter of 1.5 mm. However, extrusion molding was impossible.

As described above, the crushing strength, the nitrogen adsorption capacity, and the basic unit of calcium chloride of the samples A to F are compared and shown in the table. Here, the crushing strength is an average value obtained by measuring the strength of 100 molded bodies using a Kiya hardness meter. The nitrogen adsorption capacity is the amount of adsorption at a temperature of -10 ° C and a nitrogen pressure of 700 torr by a gravimetric method. The basic unit of calcium chloride is a value obtained by converting the amount of the aqueous solution of calcium chloride used for ion exchange into the weight of anhydrous calcium chloride, and dividing that value by the dry weight of the molded sodium A-type zeolite.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C01B 39/14 C01B 39/14 C04B 38/08 C04B 38/08 D

Claims (1)

(57) [Claims] 1. A method for manufacturing a zeolite A-shaped molded body, wherein a sodium A-type zeolite crystal powder is mixed with 5 to 15 parts by weight of a binder per 100 parts by weight of the powder, molded, fired and exchangeable. A method for producing a molded A-type zeolite, comprising performing ion exchange by contacting with a solution containing metal ions.