JPH0523587A - Production of 3a-type zeolite molding - Google Patents

Abstract

PURPOSE:To enhance resistance to spalling properties and to retain high moisture adsorption performance by molding powdery Na-A type zeolite and ion- exchanging the molding obtained by calcination and incorporating potassium ions and magnesium ions at specified amounts. CONSTITUTION:A molding is burned which is formed of both Na-A type zeolite and attapulgite type clay or montmorillonite type clay and incorporates 80/20-TO/ 3O content ratio thereof. In this obtained molded form, 50-70% of sodium ion is ion-exchanged with potassium ions and 20-3O% of sodium ion is ion-exchanged with magnesium ions. The molding which has substancially become 3A-type zeolite by ion exchange is washed with water to remove exchange liquid stuck thereto. Thereby the 3A-type zeolite molding which has high resistance to spalling resistance and retains excellent moisture adsorption performance is obtained by a simple stage and operation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a 3A type zeolite compact. Pore size 3 angstrom
The 3A-type zeolite molded product having a silica is a useful adsorbent for adsorption separation and purification, and is widely used as an adsorbent for drying cracked gas in an ethylene plant, for example.

[0002]

BACKGROUND OF THE INVENTION In cracked gas drying operations, adsorption-regeneration process cycles subject zeolite compacts to significant hydrothermal shock. That is, in the adsorption step, water is adsorbed on the 3A-type zeolite molded body, and subsequently in the regeneration step, the water is desorbed from the zeolite, and the adsorption step is performed again. In the regeneration step, a heating regeneration method is usually employed in which adsorbed water is desorbed by heating gas at 200 to 300 ° C. Therefore, the 3A-type zeolite molded product is exposed to high temperature under a high water vapor pressure in each regeneration process, and this causes the zeolite molded product to sporing (thermal shock fracture; Property), and this spalling gradually lowers the water adsorption performance. There have been some proposals in the past for a 3A type zeolite compact or a method for producing the same in order to suppress such performance deterioration as much as possible. For example, in JP-B-48-3073, "a Na-A type zeolite to ion exchange treatment, followed by molding by mixing with solid reactive amorphous silica and bentonite or attapulgus, _{[aK 2 O + bMO + cNa 2} O 3 ]:
Al ₂ O ₃ : 1.85 ± 0.5SiO ₂ : yH ₂ O (a
Is 0.3 to 0.45; b is 0.2 to 0.35; a + b +
c is 1.0 ± 0.2; M is at least one divalent cation of the alkaline earth metal group having an atomic number of 126 or less; Y has a composition of 0 to 6). 3A
Disclosed is a method for producing a highly spalling-resistant shaped body comprising at least about 68% type zeolite, 8-24% solid reactive amorphous silica, and 4-16% clay such as bentonite, attapal gas and the like. However, according to this method, solid reactive amorphous silica, which is recognized as hydrophobic, and bentonite are added to the previously ion-exchanged 3A-type zeolite to produce a molded body, so that it is possible to uniformly disperse each component. It is difficult and therefore the resulting molded article has non-uniform physical properties and poor moldability.

[0003]

As described above, the 3A type zeolite molded body produced by the conventional method is hydrophobic to the 3A type zeolite which has been ion-exchanged with the potassium ion and the divalent cation of the alkaline earth metal group in advance. Since the solid reactive amorphous silica and the clay binder, which are considered to be added, are added for molding, there is a problem in dispersibility and thus in moldability, and there is room for improvement in spooling resistance.

An object of the present invention is to provide a method for producing a 3A type zeolite molded body which is more excellent in spooling resistance than those produced by these conventional methods and has a high water adsorption capacity.

[0005]

The present inventors have found that Na-A
-Type zeolite, that is, 4A-type zeolite powder is molded, and the molded product obtained by firing is ion-exchanged to contain a specific amount of potassium ions and magnesium ions, thereby forming 3A-type zeolite having improved spooling resistance. I found that I could get a body.

The gist of the present invention consists of Na-A type zeolite and attapulgite type clay or montmorillonite type clay, the content weight ratio of which is 80/20 to 70/30.
50 to 70% of the sodium ions of the molded body which is a potassium ion, and 20 to 3 of the sodium ions
It is a method for producing a 3A type zeolite molded body by ion-exchanging 0% with magnesium ions. The details will be described below.

The zeolite used in the present invention is a Na-A type zeolite synthesized by a known method, that is, sodium aluminate and sodium silicate.

In the present invention, the content of the attapulgite-type clay or montmorillonite-type clay, which is the binder, in the molded body to be subjected to the ion exchange treatment must be 20 to 30% by weight. This is because if the amount is too small, not only the strength of the molded product but also the spalling resistance is lowered, and if it is too large, the adsorption performance is lowered.

It is easier to ion-exchange the 4A type zeolite with a higher exchange rate than to perform the ion-exchange treatment after forming the molded body as described below. The obtained molded product has low spalling resistance.

In the present invention, there is no particular limitation on the method for producing the molded body to be subjected to the ion exchange treatment, that is, the molding method and the firing method, but the molding method will be described below by the case of the extrusion molding method. First, a mixture of synthetic 4A type zeolite and an attapulgite type clay or a clay binder of montmorillonite type clay was adjusted to adjust the water content so that it could be extruded, and a lubricant was added to reduce the extrusion power. Knead and knead so that The mixture obtained by the kneading and kneading is extruded by a known extruding machine as pellets having a diameter of 3 mm, for example. The molded product thus obtained is preferably dried by a conventional method before firing, that is, at a temperature of 100 to 120 ° C. until the water content in the molded product becomes about 20% by weight. The purpose of this is to reduce the partial pressure of water vapor during calcination to prevent the deterioration of the adsorption performance of zeolite crystals caused by the deterioration of hot water. The dried molded product is fired in an atmosphere of 650 to 700 ° C. which is a usual firing temperature when these clays are used. A baking time of 4 hours or more is sufficient, and if the baking time is too long, the adsorption performance such as the amount of adsorbed water may be deteriorated, which is not preferable. By firing under the above conditions, the clay binder sinters and strongly bonds the zeolite crystals. In addition, impurities other than the clay binder that do not participate in the adsorption action, for example, the lubricant of the extrusion molding aid, is completely burned out during this firing, and is substantially negligible. Next, at least 20% by weight of the molded product obtained by firing
As described above, it is preferable to gradually humidify and, if possible, desorb the gas such as air adsorbed from the pores by an operation such as immersing in water. This operation is not essential to the present invention, but during the next operation, i.e., the treatment of contacting with a solution containing potassium ions or magnesium ions and performing ion exchange, the molded body is cracked or cracked due to rapid water adsorption. This is a preferable operation to eliminate the possibility of causing such problems. The ion exchange method may be a batch type ion exchange method which is usually performed, but a circulation type ion exchange method using a column or the like is more efficient. As described above, 50 to 70% of the sodium ions of the 4A-type zeolite must be exchanged with potassium ions, and 20 to 30% of them must be exchanged with magnesium ions by this ion exchange treatment. In both cases where the exchange rate of potassium ions is lower than the above range and higher than that range and when the exchange rate of magnesium ions is lower than the above range, the spalling resistance of the obtained molded article is low, Moreover, it is practically difficult to make the exchange rate of magnesium ions larger than the above range.

The 4A type zeolite compact is contacted with an aqueous solution containing potassium ions and magnesium ions,
50 to 70% of sodium ions are converted to potassium ions,
And 20 to 30% was exchanged for magnesium ion 3
In order to obtain the A-type zeolite, the concentration of the salt aqueous solution containing each ion, the amount thereof, the treatment temperature, the treatment time, the number of treatments (contact with the salt aqueous solution-separation from the aqueous solution-washing-the above-mentioned new aqueous solution, are used in accordance with a conventional method. The number of cycles of contact-separation-washing (...) is adjusted, and the order of ion exchange selection of potassium ions is higher than that of sodium ions, whereas that of magnesium ions is much lower. Considering the above, the ion exchange treatment may be performed. For example, a 4A type zeolite molded product is added with 4 to 5 times its weight of 0.5 to 1 normal potassium chloride and 0.5 to magnesium chloride.
A type 3 zeolite ion-exchanged within the above range can be obtained by contacting with a mixed solution of -1 N at room temperature to 40 ° C for 5 to 10 hours. Further, contact treatment of a 4A type zeolite molded product and an aqueous solution of 0.5 to 1N potassium chloride, which is 4 to 5 times its weight, at room temperature to 40 ° C. for 5 to 10 hours is performed three times or more to remove sodium ions. 90% or more is exchanged with potassium ions, and then a mixed aqueous solution of 0.2 to 0.5N potassium chloride and 0.5 to 1N magnesium chloride, which is 4 to 5 times the weight of the molded product, and 5 to 5 at room temperature to 40 ° C. The method of contacting for 15 hours can also be taken.

The ion-exchanged molded body which has become substantially 3A type zeolite is washed with water to remove the attached exchange liquid. In order to activate the obtained 3A type zeolite molded body, it may be baked after drying.

[0013]

As is apparent from the above description, according to the present invention, a 3A type zeolite molded article having a high anti-spooling property and an excellent moisture adsorption performance by a simple process and operation. Can be obtained. Therefore, for example, a molded body that has been miniaturized due to thermal shock fracture is extremely less likely to cause troubles in the apparatus or increase pressure loss.

[0014]

EXAMPLES The effects of the present invention will be specifically described below with reference to examples and comparative examples.

The anti-spooling performance is the boiling water strength ratio,
The water adsorption capacity was evaluated by the water adsorption capacity. The measuring method will be described below. <Boiling water strength ratio> About 100 g of a molded body that has been sieved with a mesh sieve is activated at 450 ° C for 60 minutes, immediately put into boiling water, and left for 5 minutes. The molded body is taken out of the boiling water and again activated at 450 ° C. for 60 minutes. After carrying out 50 cycles of this operation, the weight (Yg) of the molded product is measured, and again sieved by the above-mentioned sieve, and the weight (Xg) of the molded product remaining on the sieve is measured. The boiling water strength of the molded body was calculated by the following formula. (This X is defined as a boiling water strength rate (%)) Boiling water strength rate (%) = (X / Y) × 100 <moisture adsorption capacity> The molded body is activated at 350 ° C. for 60 minutes, cooled, and then cooled to a temperature of 25. The mixture was allowed to stand for 16 hours or more in a desiccator having a temperature of 80 ° C. and a relative humidity of 80%, and 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 Toso Corporation) 100
Mixture with 25 parts of attapulgite-type clay, and while adjusting the water content, add 3 parts of CMC (carboxymethylcellulose) powder as an extrusion lubricant and add a granulator (M
kneading and kneading in an ix-Muller). Next, the kneaded product was supplied to an extruder equipped with a die plate having a diameter of 3 mm and extruded into pellets. After drying at 120 ° C, the particles were sized to a length of 5 to 10 mm and calcined in a muffle furnace at a temperature of 650 ° C for 4 hours.

After cooling, 500 g of the fired pellets were immersed in water to degas, then drained, and mixed solution 2 of potassium chloride having a concentration of 1N and magnesium chloride having a concentration of 2N.
Ion exchange was performed in a batch system by contacting with 000 ml at 40 ° C. for 10 hours. This product was washed with water until the washing liquid contained no chlorine ions, dried at 120 ° C, and then washed at 400 ° C for 1 hour.
It was fired for an hour and activated. The ion composition of the obtained molded product was 51.7 mol% potassium ion and 2 magnesium ion.
3.5 mol% and the rest was sodium ion. As a result of evaluating the physical properties of this product by the above-mentioned methods, the boiling water strength ratio was 96.1%. The water adsorption capacity is 23.9%.
Met.

Examples 2 to 9 Comparative Examples 1 to 7 were carried out under the same conditions as in Example 1 except for those shown in the table below. Tables 1 and 2 show the results of evaluating the physical properties of the obtained molded product by the above-mentioned methods.

Table 1 ActualBinder (part) Ion exchange rate (%) Boiling water strength Water adsorptionK Mg Frequency rate (%) capacity(%)  An example  2 Attapal 25 55.5 27.3 95.8 23.9 3 Attapal 25 59.5 28.5 96.2 23.7 4 Attapal 25 69.8 21.1 98.0 23.2 5 Attapal 33 53. 9 25.1 98.8 22.9 6 Attapal 33 61.3 23.4 98.9 22.8 7 Montmory 25 52.3 28.2 96.3 23.5 8 Montmory 25 68.7 24.0 98 4 23.1 9 Montmorillon 33 60.6 24.9 99.0 22.6 Note) In the table, "atapal" means attapulgite and
And "Montmori" means montmorillonite, respectively.
It (Part) of the binder is 100 parts of raw material 4A type zeolite.
The amount is same as below.

Table 2 ratioBinder (part) Ion exchange rate (%) Boiling water strength Water absorption comparisonK Mg Frequency rate (%) capacity(%)  An example  1 Attapal 25 45.0 0.0 89.0 22.2 2 Attapal 25 47.7 24.8 93.5 23.5 3 Attapal 25 75.0 5.5 98.5 20.9 4 Attapal 18 61. 2 26.3 91.3 24.3 5 Attapal 55 58.8 21.7 99.5 20.1 6 Montmory 25 40.8 27.0 93.9 23.1 7 Montmory 25 55.6 18.9 94 .1 22.2

Claims (1)

Claims: 1. A molded body comprising Na-A type zeolite and attapulgite type clay or montmorillonite type clay, the content weight ratio of which is 50/20 to 70/30, and 50 to 30% of sodium ion. A method for producing a 3A type zeolite molded body, which comprises subjecting 70% of potassium ions to ion exchange and 20 to 30% of the sodium ions to magnesium ions.