JPH05317700A - 3A type zeolite compact - Google Patents

Abstract

(57) [Summary] [Structure] A 3A-type zeolite ion-exchanged with K ions in an amount of 16% or more and less than 35% and a binder.
10 to 100 parts by weight of the binder per 100 parts by weight of zeolite
A 3A type zeolite compact containing 30 parts by weight. [Effect] It has excellent moisture selective adsorption performance, moisture adsorption capacity and spalling resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 3A type zeolite compact. 3A type zeolite has a pore size of about 3 angstroms and is used for industrial purposes as a water adsorbent, gas desiccant, etc. by utilizing the fact that it hardly adsorbs molecules other than water. It is widely used as an adsorbent for drying decomposed gas.

[0002]

2. Description of the Related Art A conventional 3A type zeolite has a K ion exchange rate of 35% or more. K ion exchange rate of 35
It is designed so that substances other than water are not adsorbed when the content is at least%.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The 3A type zeolite thus K ion-exchanged is
It is known that the water adsorption performance is extremely poor.

In the water adsorption operation, the adsorption-regeneration cycle process is repeated, whereby a considerable thermal shock or thermal stress is applied to the zeolite or its molded body.
For example, in the drying operation of decomposed gas, several tens of kgf / c
Water is adsorbed under a pressure of about m ² , and then the pressure is lowered to perform dehydration, that is, regeneration under a pressure of about several kgf / cm ² . This depressurization lowers the temperature, partly -1
The adsorbed water may freeze up to about 0 ° C. In the regeneration step, usually, a heating regeneration system is adopted in which adsorbed water or frozen water is desorbed by heating gas at 200 to 300 ° C. And by repeating these operations, the zeolite molded body causes spalling (cracking or collapse of the molded body due to thermal shock and thermal stress. Hereinafter, the property of withstanding thermal shock and thermal stress is referred to as spalling resistance), The fine particles generated thereby fill the grain boundaries, increase the pressure loss in the adsorption bed, and reduce the gas flow rate to be passed.

The present invention has solved such a problem, that is, 3A having a higher water adsorption performance than the conventional 3A type zeolite molded product and having excellent spalling resistance.
The object of the present invention is to provide a type zeolite molded product.

[0006]

Means for Solving the Problems The present inventors do not need to have a K ion exchange rate of 35% or more, but less than 35%, in order to improve the moisture selective adsorption performance of a 3A type zeolite molded body. Is sufficient if it is also 16% or more. By lowering the K ion exchange rate, it is possible to increase the water adsorption capacity without degrading the water selective adsorption performance in practice; It has been found that 3A type zeolite is superior in spalling resistance as compared with that of 35% or more. The present invention has been made based on such new findings. That is, the present invention comprises 3A type zeolite ion-exchanged with K ions in an amount of 16% or more and less than 35% and a binder,
The gist is a 3A type zeolite compact containing 10 to 30 parts by weight of the binder per 100 parts by weight of the 3A type zeolite.

The present invention will be described in detail below.

The K ion exchange rate of the 3A type zeolite in the molded article of the present invention must be in the range of 16% or more and less than 35%. If the K ion exchange rate is 35% or more, the water adsorption capacity is too low; if it is less than 16%, adsorption of components other than water, especially components having a larger molecule than water contained in the gas to be treated, cannot be ignored. May be; 1
This is because if it is 6% or more and less than 35%, components other than water are not substantially adsorbed and the water adsorption capacity is increased. However, when a gas containing acetylene or ethane is treated with a K ion exchange rate of less than 20%, these may be adsorbed to cause coking and impair the adsorption performance. Therefore, it is particularly preferably in the range of 20% or more and less than 35%. The water adsorption amount of the 3A type zeolite of the molded article of the present invention is 0.26 to 1 g of zeolite.
It is 0.28 grams.

The binder content should be 10 to 30 parts by weight per 100 parts by weight of zeolite. If it is less than 10 parts by weight, the spalling strength will not be sufficiently high, and if it exceeds 30 parts by weight, the amount of adsorbed water will decrease. Above all, 20 to 30 parts by weight is preferable. The water adsorption amount per 1 gram of the molded article of the present invention is
It is 0.225 to 0.24 grams.

The kind of the binder is not particularly limited, but since the strength of the molded body depends on the adhesiveness between the zeolite and the binder, it is preferable to use clay having good sinterability as the binder. For example, attapulgite type clay, montmorillonite type clay, kaolinite type clay and the like are used.

The 3A type zeolite compact of the present invention is produced by a known method, for example, NaA type zeolite synthesized from sodium aluminate and sodium silicate, that is, 4A type zeolite is used as a starting material, and the powder of the 4A type zeolite is KCl, Ion exchange is performed with a solution containing K ions such as KOH, and the binder / zeolite weight ratio is 10 to 30/10.
It is mixed with a binder so as to be 0, shaped, and then calcined; or a 4A type zeolite powder is subjected to the following ion exchange so that the binder / zeolite weight ratio is 10 to 30/100.
Mix with the binder in the following ratio, mold, sinter, and K
It can be produced by ion-exchanging with a solution containing ions and drying. By any of these methods, the amount of K ions in the solution containing K ions is 4A.
The amount is preferably 0.1 to 0.5 mol per 100 g of type zeolite. If this is less than 0.1 moles, a perfect 3
This is because it does not become an A-type zeolite, and if it exceeds 0.5 mol, the K ion exchange rate becomes 35% or more. The pH of the solution during K ion exchange is preferably 7 or higher. This is because in a pH of less than 7, that is, in an acidic atmosphere, zeolite crystals become unstable, defects occur in the crystal structure, or the crystal structure itself collapses, resulting in a significant decrease in water adsorption capacity.

Hereinafter, a case will be described as an example in which attapulgite is used as a clay-based binder to form a pellet molded body by extrusion molding.

First, a mixture prepared so as to contain 10 to 30 parts by weight of a binder with respect to 100 parts by weight of zeolite (calculated as 3A type zeolite) used in the method for producing a molded article by the above two methods is extruded. Extruding aids (eg carboxymethylcellulose) to adjust its water content and, if necessary, reduce extrusion power
After adding, all the components are uniformly mixed, and the mixture is extruded with a known extruder as pellets having a diameter of 1.5 mm or 3 mm, for example. The obtained molded product is preferably dried by a conventional method, that is, in the temperature range of 100 to 120 ° C. until the water content in the molded product becomes about 20% by weight. This is to prevent deterioration of the adsorption performance of zeolite crystals caused by hot water deterioration due to firing under a high steam partial pressure state. In order to sinter the binder in the dried molded body, it is usually 650 ° C.
Baking at a baking temperature of 700 ° C. Firing time is usually 2-4
It takes about a time, and if it is fired for a longer time than necessary, the adsorption performance such as the amount of adsorbed water is deteriorated, which is not preferable. By firing under such conditions, the clay binder sinters and strongly bonds the zeolite crystals. Impurities other than the clay binder, which do not participate in the adsorption action at all, such as extrusion aids, are all burned out by this firing and become substantially negligible.

When a 4A type zeolite containing a binder is used to form a molded body, it is brought into contact with a solution containing K ions as described above, for example, a solution of KCl, KOH or the like to carry out K ion exchange. At this time, in order to prevent cracks and crevices of the molded body due to rapid water adsorption, the water content was gradually moistened and hydrated so that the water content became 20% by weight or more, and the water was adsorbed from the pores. It is better to desorb gas such as air. The ion exchange method may be either a batch type ion exchange method or a circulation type ion exchange method using a column or the like, but the circulation type ion exchange method is more efficient. The humidified hydrated 4A type zeolite compact was brought into contact with a solution containing K ions to obtain 16% of Na ions.
In order to obtain a 3A type zeolite molded body in which the range of less than 35% is replaced with K ions, as in the above 3A type zeolite manufacturing method, K ion per 100 g of 4A type zeolite in the 4A type zeolite molded body containing a binder. 0.
It is better to replace it with 1 to 0.5 mol. Ion exchange 3
The molded body that has become the A-type zeolite is washed with water to remove the adhering salt aqueous solution containing K ions. In order to activate the thus obtained 3A-type zeolite molded body, it may be dried and then baked at room temperature, for example, 400 ° C.

[0015]

As described above, in the gas drying treatment, the temperature of the 3A type zeolite repeatedly rises and falls between −10 ° C. and 200 to 300 ° C. When the lattice constant during this temperature was measured for 3A type zeolite having a K ion exchange rate of less than 35% and that of 35% or more, the variation of the lattice constant between the former is smaller than that of the latter. Therefore,
It is clear that the expansion / contraction of the 3A type zeolite having a K ion exchange rate of less than 35% due to temperature fluctuations during adsorption-regeneration is smaller than that of 35% or more. 3A of the present invention
It is recognized that at least one of the reasons why the type zeolite molded article is excellent in spalling resistance is that the expansion coefficient is small.

[0016]

As is apparent from the above description, the 3A type zeolite molded body of the present invention is manufactured by the conventional technique.
Compared to A-type zeolite compact, it has superior moisture adsorption performance,
In addition, it is excellent in mechanical properties such as prevention of cracking and collapse of the molded body due to thermal shock and thermal stress, that is, spalling resistance. Therefore, when it is used for drying gas, etc., it is possible to continue the operation while maintaining a high water adsorption capacity for a long time.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

The measuring methods in the examples and comparative examples are as follows. <Method for measuring nitrogen adsorption capacity> The nitrogen adsorption capacity was measured by the volume method. The zeolite compact is activated at a pressure of 0.01 mmHg or less at 350 ° C. for 120 minutes, and after cooling, nitrogen gas is introduced, the adsorption temperature is −10 ° C., the adsorption pressure is 700 mmH.
The adsorption capacity (adsorption amount per zeolite weight, Ncc / g) was measured after the adsorption was sufficiently equilibrated.
The shortest diameter of nitrogen gas is 3.2 angstrom.
That is, not adsorbing nitrogen gas means that it is a 3A type zeolite molded body. <Water Freezing-Drying Strength Measuring Method> About 50 grams of a molded body that has been sieved with a 7-mesh sieve is dried at 200 ° C for 2 hours, then immersed in water at 25 ° C and left for 5 minutes. Next, this molded body is immersed in liquid nitrogen for 5 minutes to freeze the water, and then dried again at 200 ° C. for 2 hours. After 20 cycles of this operation, they were sieved again by the above-mentioned sieve, and the weight (Xg) of the molded body remaining on the sieve was measured. The water freeze-drying strength of the molded product was calculated by the following formula.

Moisture freeze-drying strength (%) = (X / total weight) × 100 <Method for measuring water adsorption capacity> 350 ° C.
After activating for 60 minutes, after cooling, temperature 25 ℃, relative humidity 8
After standing for 16 hours or more in a 0% desiccator, the equilibrium moisture adsorption capacity adsorbed on the molded body was measured.

"Parts" in the following specific examples are by weight.

Example 1 4A type synthetic zeolite powder (manufactured by Tosoh Corporation) 100
Aqueous potassium chloride solution 10 containing 0.12 mol of K ion
It was immersed in 00 ml at 60 ° C. for 3 hours to perform ion exchange in a batch system. When the ion exchange rate of the zeolite after washing and removing the attached water was examined by atomic absorption, it was 16.2%, and the rest was sodium ion.

100 parts of this 3A type synthetic zeolite powder was mixed with 25 parts of attapulgite type clay and 3 parts of carboxymethyl cellulose powder as an extrusion lubricant, and kneading and kneading while adjusting water content in a granulator (Mix-Muller). I made it Next, this kneaded product was supplied to an extrusion molding machine equipped with a die plate having a diameter of 3 mm and extruded into pellets. After drying at 120 ℃, length 5
The thickness was adjusted to -10 mm and the mixture was baked at 650 ° C. for 4 hours using a muffle furnace.

The nitrogen adsorption capacity, the water freeze-drying strength and the water adsorption capacity of this product were measured.
It was 0 Ncc / g, 97.6%, and 23.9 wt%.

Further, as a result of examining the lattice constant in the temperature range of -10 ° C to 300 ° C, as in the case of not exchanging with potassium ions, that is, the 4A type zeolite molded body, around 100 ° C to about 24.5 angstroms. Although it contracted once, it became the lattice constant of the base, that is, 24.6 angstrom after dehydration, and hardly changed in the whole temperature range. This means that the thermal stress due to thermal expansion and thermal contraction is small and the spalling strength is strong.

Examples 2 to 4 Comparative Examples 1 to 7 Example 1 except that the amount of binder and the amount of K ions were changed.
A 3A type zeolite compact was prepared under the same conditions as described above.
The physical properties thereof are shown in Table 1.

Example 5 4A type synthetic zeolite powder (manufactured by Tosoh Corporation) 100
25 parts of attapulgite-type clay and 3 parts of carboxymethylcellulose powder as an extrusion lubricant were mixed with the parts, and kneaded and kneaded while adjusting the water content in a granulator (Mix-Muller). Next, this kneaded product has a diameter of 3 m
It was supplied to an extrusion molding machine equipped with a m die plate and extruded into pellets.

After drying at 120 ° C., length 5-10 mm
And was fired at 650 ° C. for 4 hours using a muffle furnace.

After cooling, 125 g of the calcined pellets were hydrated and degassed, and then immersed in 1000 ml of an aqueous potassium chloride solution containing 0.12 mol of K ions at 60 ° C. for 3 hours for batch-type ion exchange. After that, the molded body that had been thoroughly washed to remove the attached water was dried at 120 ° C., and activated by firing at 400 ° C. for 1 hour. The ion exchange rate of the thus obtained zeolite compact was examined by atomic absorption.
It was 6.2%, and the remaining ions were sodium ions.

When the physical properties of this product were evaluated by the methods described above, the nitrogen adsorption capacity was 0.0 Ncc / g, the water freeze-drying strength was 98.3%, and the water adsorption capacity was 24.0 wt.
%Met.

Examples 6 to 8 Comparative Examples 8 to 14 Example 5 except that the amount of binder and the amount of K ions are changed.
A 3A type zeolite compact was prepared under the same conditions as described above.
The physical properties thereof are shown in Table 2.

Table 1 Vine K ion K ion Nitrogen adsorption Moisture freezing Moisture adsorption Dar amount Exchange rate Capacity Dry strength Capacity part by weight mol % Ncc / g % wt% Example 2 25 0.18 20.1 0.0 97.9 24.2 3 14 0.22 24.9 0.0 98.5 24.1 4 22 0.43 33.5 0.0 97.0 23.5 Comparative Example 1 25 0.04 7.1 18.1 97.8 23.6 2 8 0.18 20.1 0.0 13.2 23.6 3 40 0.18 20.1 0.0 96.0 17.1 4 25 0.71 44.5 0. 0 79.4 21.9 5 25 1.10 52.8 0.0 78.2 21.5 6 25 1.89 62.1 0.0 81.5 21.4 7 25 3.52 70.1 0 0.0 86.3 20.8

Table 2 Vine K ion K ion Nitrogen adsorption Moisture freezing Moisture adsorption Der amount Exchange rate Capacity Dry strength Capacity part by weight mol % Ncc / g % wt% Example 6 25 0.18 20.1 0.0 98.2 23.9 7 14 0.22 24.9 0.0 98.9 24.1 8 22 0.43 33.5 0.0 97.5 23.3 Comparative Example 8 25 0.04 7.1 18.0 97.2 23.9 9 8 0.18 20.1 0.0 9.3 24.1 10 40 0.18 20.1 0.0 97.5 16.8 11 25 0.71 44.5 0. 0 79.7 21.8 12 25 1.10 52.8 0.0 77.1 21.6 13 25 1.89 62.1 0.0 80.6 21.3 14 25 3.52 70.1 0 0.0 84.8 20.9

Claims (1)

[Claims] 1. A 3A-type zeolite ion-exchanged with K ions in an amount of 16% or more and less than 35% and a binder, and the binder is used in an amount of 100 parts by weight of the 3A-type zeolite.
A 3A type zeolite compact containing 0 to 30 parts by weight.