JPH04104836A - Manufacture of zeolite adsorbent - Google Patents

Abstract

PURPOSE:To obtain an adsorbent in which zeolite component itself has high adsorbing capacity by executing ion exchanging in zeolite with alkali earth metal ions till the amt. of the cations in the zeolite increases to a certain one and then bringing the zeolite into contact with a sodium ion-contg. soln. CONSTITUTION:The powder or formed body of zeolite is brought into contact with an aq. soln. contg. alkali earth metal ions such as calcium ions, and ion exchanging is executed till >=0.9 equivalent fraction of the cations in the zeolite is converted into the alkali earth metal. Next, in this zeolite, ion exchanging is executed with an aq. soln. contg. sodium ions to reduce the equivalent fraction of the alkali earth metal ions into the range of 0.6 to 0.9 equivalent fraction. Thus, the alkali earth metal ion exchanging type zeolite adsorbent in which zeolite component itself has high adsorbing capacity can be obtd.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an alkaline earth ion exchange type zeolite adsorbent used as an adsorption/separation agent, etc. The present invention relates to a method for producing a calcium ion exchange type zeolite adsorbent suitable for use for purposes such as separating, purifying, and concentrating oxygen by a method.

[Prior art] Zeolite is a crystalline aluminone liquede with pores on the order of a few molecules, and many types of zeolite have been artificially synthesized, including those with structures that do not exist in nature. .

Many of these zeolites have their adsorption and catalytic properties adjusted by replacing the exchangeable cations in the zeolite crystals with other cations through ion exchange, and are widely used industrially as adsorbents and catalysts. ing. The zeolites currently most commonly used industrially are A-type zeolite and faujasite-type zeolite.

Hereinafter, a description will be given using type A zeolite as an example.

Type A zeolite can be used, for example, by adjusting the pore size of the zeolite to about 5 pores by exchanging calcium ions, and selectively adsorbing and separating n-paraffins from hydrocarbon mixtures, and separating n-butylene, a raw material for butadiene production, from a butane-butylene fraction. It is used for separating and concentrating oxygen from the air.

Type A zeolite with a pore size of 5 mm is usually produced as follows. First, synthetic sodium A-type zeolite powder is ion-exchanged in a calcium chloride aqueous solution, and sodium ions with an equivalent fraction of 0.67 or more are exchanged with calcium ions to adjust the pore size to 5. After separating from the mother liquor, wash with washing water. When used as a molded article, a binder is further added and molded. Clay-based binders are often used as binders. In addition, condensate to which a molding aid such as carboxymethyl cellulose has been added is mixed, thoroughly kneaded, and molded by a conventional molding method such as extrusion molding. Finally, 4
By firing at a temperature of 50 to 700°C, a molded body of A-type zeolite with a pore diameter of 5 and having a physical strength suitable for industrial use is obtained.

[Problem to be solved by the invention] The adsorption capacity of alkaline earth metal ion-exchanged zeolite produced using conventional technology is not necessarily high, and if an adsorbent with a larger adsorption capacity can be produced, the amount of adsorbent used will be reduced. can be reduced, making it possible to downsize the adsorption device. As a result, power cost can be reduced. However, increasing adsorption capacity is not easy, and efforts have been made to reduce the amount of binder added during molding and develop binderless technology, but no substantial increase in adsorption capacity has been achieved. There wasn't.

An object of the present invention is to provide a method capable of producing an alkaline earth metal ion exchange type zeolite adsorbent in which the zeolite component itself has a high adsorption capacity.

[Means for Solving the Problems] As a result of intensive studies on ion exchange methods for zeolite, the present inventors discovered irreversibility in the relationship between ion exchange rate and adsorption capacity, leading to the present invention.

Exchange of cations contained in zeolite crystals is often reversible. On the other hand, the adsorption capacity for nitrogen, etc. is closely related to the type of cations in the zeolite crystals and the ion exchange rate. Therefore, if ion exchange is performed reversibly,
It can be easily inferred that the adsorption capacity will also change reversibly. However, when the present inventors examined the relationship between ion exchange rate and adsorption capacity in detail, they found that even if ion exchange is performed reversibly, the adsorption capacity may change irreversibly. I found out.

In other words, the gist of the present invention is that when ion-exchanging zeolite, the zeolite is ion-exchanged until more than 0.1 g equivalent fraction of its cations become alkaline earth metal ions. ), and then brought into contact with a solution containing sodium ions to reduce the equivalent fraction of the alkaline earth metal ions to 0.
A method for producing a zeolite adsorbent comprises adjusting the ion exchange treatment step to a range of 6 to 01 g equivalent fraction (hereinafter, this ion exchange treatment step is referred to as the second step). The details will be explained below.

The present invention is an improved method for producing zeolite containing alkaline earth metal ions as cations, and the starting material zeolite may be naturally occurring or synthesized by a known method; The alkaline earth metal ions included by ion exchange may also be any ions such as calcium, strontium, etc. However,
Type A zeolite containing calcium ions, ie type 5A zeolite, is widely used, and the present invention can also be effectively applied to the production of type 5A zeolite.

The form of the zeolite to be subjected to ion exchange may be a powder or a crushed product, or it may be formed into a compact body as in the ion exchange method shown in JP-A-55-104913, JP-A-2-180618, etc. It may be something that exists. Furthermore, it is even more effective if it has undergone binderless processing. Usually the cation is a sodium ion.

(First step) Such a zeolite powder or compact is brought into contact with an aqueous solution containing alkaline earth metal ions such as calcium ions to undergo ion exchange.

Compounds that produce alkaline earth metals when dissolved in water include the most commonly used chlorides, as well as nitrates, sulfates, carbonates, and bicarbonates.

Among acetates, hydroxides, oxides, etc., those having sufficient solubility can be used. The concentration of the aqueous solution used for ion exchange is not particularly limited, but a concentration of 2N or less is preferable. Further, the temperature of ion exchange is not limited either, but from the viewpoint of efficiency such as ion exchange rate, it is preferably 40 to 90°C. The ratio of the zeolite to the solution cannot be limited as it depends on the concentration, temperature, etc. of the solution, but it is necessary to ion-exchange 0.9 equivalent fraction or more of the cations in the zeolite to alkaline earth metal ions. It is sufficient as long as the ratio is sufficient.

Under these conditions, the zeolite is made to have an alkaline earth metal ion equivalent fraction of 01 g or more. The ion exchange method may be a batch method, a column flow method, or the like.

After this ion exchange, it may be preferable to separate it from the mother liquor and wash it, but washing is not an essential operation for the present invention. Furthermore, it is not essential to apply heat for drying or the like.

(Second step) Next, as described above, 01g of alkaline earth metal ion
The zeolite having an equivalent fraction or more is ion-exchanged with an aqueous solution containing sodium ions to reduce the equivalent fraction of alkaline earth metal ions to a range of 0.6 to 0.1 g equivalent fraction. The aqueous solution containing sodium ions used for ion exchange is an aqueous solution of sodium salts such as sodium chloride. In addition to sodium chloride, nitrates, sulfates, carbonates, and bicarbonates.

Acetate, hydroxide, etc. can also be used. The concentration of the aqueous solution used for ion exchange is not particularly limited, but a concentration of 2N or less is preferred. Further, the temperature of ion exchange is not limited, but it is preferably 40 to 90°C from the viewpoint of ion exchange rate. In this step, as in the first step, any method such as a batch method or a column flow method can be employed.

After ion exchange, it is separated from the mother liquor by a conventional method, washed, and
It is dried at ~150°C and activated at 350-500°C to form an adsorbent (if zeolite powder is used as the starting material,
After drying, it is shaped and then activated).

[Function] The higher the exchange rate of alkaline earth metal ions in the first step, the higher the adsorption capacity of the product that can be obtained in the second step. In the present invention, the alkaline earth metal ion equivalent fraction in the first step is 0.
This is the reason why it is set to 9 or more, but the degree of contribution to the adsorption capacity of the product obtained through the second step is determined by the value of the alkaline earth metal ion equivalent fraction in the second step. is larger. If this value is set too low, there is a risk that the adsorption capacity will be lower than that obtained by only the first step. Due to process only (alkaline earth metal ion equivalent fraction 0.9
The adsorption capacity is higher than the above).

If an equivalent fraction of 0.7 to 08 is selected from the above range of 06 to 09, the adsorption capacity will be further increased.

[Effects of the Invention] As is clear from the above explanation, according to the method of the present invention, (1) an adsorbent with a large adsorption capacity can be produced (
(2) As a result, the amount of adsorbent used can be reduced, making it possible to increase the adsorption capacity by more than 10% compared to conventional methods with an alkali metal ion equivalent fraction of 0.9 or more. It becomes possible to downsize.

[Example code] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 100 parts by weight of powder (approximately 100 mesh) of commercially available sodium A-type zeolite (Zeolum A4, manufactured by Tosoh Corporation), 20 parts by weight of a clay-based binder, and an organic forming aid (
5 parts by weight of sodium carboxymethylcellulose (sodium carboxymethylcellulose salt) were mixed, kneaded with water added, and extruded using a regular extruder by passing through a die with an inner diameter of 1.5 mm to give a length of approximately 5 to 15 mm. A molded body of the link was obtained. This molded body was dried in a ventilation dryer at a temperature of 110° C. until the moisture content of the molded body became 25 vt% or less. Next, it was fired in a furnace at 550°C for 2 hours. The moisture content of the fired molded body was 2vt%. This molded body was heated to a moisture content of 20
It was hydrated to vt%. This molded body is hereinafter referred to as "molded body 1."

Approximately 300 g of "Molded Body 1" was packed into a column having a diameter of 200 mm and a length of 200 mm. An aqueous IN calcium chloride solution was heated to 80° C. and passed through the column from the bottom to the top at a flow rate of 4.2 cc/min. The circulation time was 12 hours. After the flow of the calcium chloride aqueous solution was completed, the calcium chloride aqueous solution in the column was drained and washed with distilled water. Distilled water was passed from the bottom of the column to the top of the column for 2 hours at a flow rate of 30 ec/min while remaining at room temperature (approximately 20° C.). After washing, the molded body is taken out from the column and placed in a ventilation dryer.
The molded body was dried at a temperature of 10°C until the moisture content of the molded body became 25 wt% or less. The calcium ion exchange rate of the dried molded body was measured by atomic absorption spectrometry and was found to be 0.928 equivalent fraction.

The sample prepared in this way is hereinafter referred to as "Sample-1".
It's called. "Sample-1" -10℃, 700torr
When the nitrogen adsorption capacity was measured by volumetric method, it was found that 26
．． It was 0Ncc/g. Binder added during molding (20
When calculated by subtracting the amount (parts by weight), it was 31.2 Ncc/g.

40 g of Sample-IJ was further brought into contact with 140 cc of a 0.3N sodium chloride aqueous solution at a temperature of 40°C for 3 hours to carry out ion exchange. After ion exchange, it was separated from the mother liquor, washed, and then dried at 100°C for 2 hours.

The calcium ion exchange rate of the dried molded body was measured and found to be 0.850 equivalent fraction. Also, -10℃
The nitrogen adsorption capacity at 700 torr was measured by a capacitance method and was 29.1 Ncc/g, and when calculated by subtracting the binder (20 parts by weight) added during molding, it was 34.
It was 9Ncc/g. Compared to "Sample 1", the adsorption capacity increased by 11.9% even though the calcium ion exchange rate decreased.

Example 2 40 g of Sample-IJ obtained in Example 1 was further
．． Ion exchange was performed by contacting with 140 cc of a 5N aqueous sodium chloride solution at a temperature of 40° C. for 3 hours. After ion exchange, it was separated from the mother liquor, washed, and dried at 100° C. for 2 hours. The calcium ion exchange rate of the dried molded body was measured and found to be 0.812 equivalent fraction. Also, -10℃, 7
When the nitrogen adsorption capacity at 00 torr was determined by the volumetric method, it was 29.3 Ncc/g, and when calculated by subtracting the binder (20 parts by weight) added during molding, it was 35.2
It was Ncc/g. Compared to "Sample-1", the adsorption capacity increased by 12.7% even though the calcium ion exchange rate decreased.

Example 3 40 g of Sample-I obtained in Example 1 was further heated with 140 cc of ON sodium chloride aqueous solution at 40°C.
Ion exchange was performed by contacting at a temperature of 3 hours. After ion exchange, it was separated from the mother liquor, washed, and dried at 100°C for 2 hours. The calcium ion exchange rate of the dried molded body was measured and found to be 0.733 equivalent fraction. Also, -10
The nitrogen adsorption capacity at 700 torr at ℃ was measured by the capacitance method and found to be 29.6 Ncc/g, and when calculated by subtracting the binder (20 parts by weight) added during molding, it was 35
．． It was 5Ncc/g. Compared to "Sample-1", the adsorption capacity increased by 13.9% even though the calcium ion exchange rate decreased.

Example 4 40g of Sample-IJ obtained in Example 1 was further
．． Ion exchange was performed by contacting with 140 cc of 2N aqueous sodium chloride solution at a temperature of 40° C. for 3 hours. After ion exchange, it was separated from the mother liquor, washed, and dried at 100°C for 2 hours. The calcium ion exchange rate of the dried molded body was measured and found to be 0.871 equivalent fraction. Also, -10℃, 7
When the nitrogen adsorption capacity at 00tOrr was measured by the capacitive method, it was 28.4Ncc/g, and when calculated by subtracting the binder (20 parts by weight) added during molding, it was 34.1N.
cc/g. Compared to "Sample-1", the adsorption capacity increased by 9.2% even though the calcium ion exchange rate decreased.

Example 5 40 g of Sample-IJ obtained in Example 1 was further
．． Ion exchange was performed by contacting with 140 cc of a 5N aqueous sodium chloride solution at a temperature of 40° C. for 3 hours. After ion exchange, it was separated from the mother liquor and washed with 500 cc of distilled water. This operation was repeated a total of three times.

Then, it was dried at 100°C for 2 hours. As a result of measuring the calcium ion exchange rate of the molded product after drying, it was found to be 0.62.
The equivalent fraction was 1. Also, -10℃, 700tOrr
When the nitrogen adsorption capacity of 2B was measured by volumetric method, it was found that 2B
, [1 Ncc/g, and the binder added during molding (20
When calculated by subtracting the amount (parts by weight), it was 31.9 Ncc/g. Compared to "Sample-1", although the calcium ion exchange rate has decreased, the adsorption capacity is 2.3%.
increased.

Example 6 Powder (approximately 100 mesh or less) of commercially available sodium A-type zeolite (Zeolum A4, manufactured by Tosoh Corporation) 2
00g with 1000cc of 2N calcium chloride aqueous solution and 70g
Ion exchange was performed by contacting for 3 hours at a temperature of .degree. After ion exchange, it was separated from the mother liquor and washed with 2500 cc of distilled water. This operation was repeated a total of three times. After the third ion exchange, it was washed and dried at 100°C for 2 hours. The calcium ion exchange rate of the type A zeolite powder after drying was measured and found to be 0.918 equivalent fraction. The sample prepared in this manner is hereinafter referred to as "Sample-2." The nitrogen adsorption capacity of "Sample-2" at -10°C and 700 torr was measured by a capacitance method and was found to be 31.0 Ncc/g.
Met.

[40 g of Sample-2J was further brought into contact with 140 cc of 0.3N aqueous sodium chloride solution at a temperature of 40°C for 3 hours to perform ion exchange. After ion exchange, it was separated from the mother liquor, washed, and dried at 100°C for 2 hours.

The calcium ion exchange rate of the dried molded body was measured and found to be 0.871 equivalent fraction. Also, -10℃
, the nitrogen adsorption capacity at 700 torr was measured by a capacitance method, and it was 34.3 Ncc/g, which was 34.3 Ncc/g.
Even though the calcium ion exchange rate decreased compared to "2", the adsorption capacity increased by 10.8%.

Comparative Example 1 Ion exchange was performed by contacting 40 g of the molded object IJ obtained in Example 1 with 100 cc of a 2N sodium chloride aqueous solution at a temperature of 70° C. for 3 hours. After ion exchange, it was separated from the mother liquor,
It was washed with 500 cc of distilled water and dried at 100°C for 2 hours. The calcium ion exchange rate of the dried molded body was measured and found to be 0.715 equivalent fraction. Also, -1
The nitrogen adsorption capacity at 0°C and 700 torr was measured by the capacitance method and was 22.1 Ncc/g, which was calculated by subtracting the binder (20 parts by weight) added during molding.
It was 6.5Ncc/g. The adsorption capacity is 33.9% lower than that in Example 3, which has approximately the same calcium ion exchange rate.

Comparative Example 2 Ion exchange was performed by contacting 40 g of the molded object IJ obtained in Example 1 with 200 cc of a 2N sodium chloride aqueous solution at a temperature of 70° C. for 3 hours. After ion exchange, it was separated from the mother liquor,
It was washed with 500 cc of distilled water.

This operation was repeated a total of two times. Then, it was dried at 100''C for 2 hours.The calcium ion exchange rate of the dried molded body was measured and found to be 0.808 equivalent fraction. When measured by the method, it was 22.5 Nec/g, and when calculated by subtracting the binder (20 parts by weight) added during molding, it was 27.0 Nec/g.The adsorption capacity was approximately equal to the calcium ion exchange rate. Compared to that in Example 2, it is 30.2% lower.

Comparative Example 3 Ion exchange was performed by contacting 40 g of sample IJ obtained in Example 1 with 140 cc of a 2N sodium chloride aqueous solution at a temperature of 40°C for 3 hours. This ion exchange operation was repeated a total of two times. After separating and washing the mother liquor, it was dried at 100°C for 2 hours.The calcium ion exchange rate of the dried molded body was measured and found to be 0.562 equivalent fraction. When the nitrogen adsorption capacity at 700 torr was measured by capacitance method, it was 23.3.
Nec/g, and when calculated by subtracting the binder (20 parts by weight) added during molding, it was 28°0 Nec/g.

Compared to "Sample-1", it is reduced by 10.4%.

Claims (3)

[Claims] (1) When ion-exchanging zeolite, zeolite is ion-exchanged until 0.9 equivalent fraction or more of its cations become alkaline earth metal ions, and then brought into contact with a solution containing sodium ions to form alkaline earth metal ions. A method for producing a zeolite adsorbent, which comprises reducing the equivalent fraction of earth metal ions to a range of 0.6 to 0.9. (2) Claim (1) wherein the zeolite is an A-type zeolite.
) The method for producing a zeolite adsorbent as described in . (3) Claim in which the alkaline earth metal is calcium (
The method for producing a zeolite adsorbent according to 1) or (2).