JPH02157119A - Production of binderless zeolite molded product - Google Patents

Abstract

PURPOSE:To obtain the subject molded product having excellent mechanical strength and high adsorption capacity by extrusion-molding the mixture of synthetic 4A-type zeolite powder, kaolin-type clay, and NaOH in a specified ratio, calcining the molded product and converting the clay into 4A-type zeolite in an aq. NaOH soln. CONSTITUTION:The synthetic 4A-type zeolite powder obtained by the well- known method, 20-30wt.% kaolin-type clay based on the total amt. of the clay and zeolite powder, and NaOH in the amt. equivalent to <=25% of the stoichiometric amt. necessary for converting the clay to 4A-type zeolite are mixed and kneaded. The obtained mixture is molded by a well-known extruder, and the molded product is dried at 100-200 deg.C to about 20wt.% water content. The dried molded product is sized, for example, into a pellet having 5-15mm length, and the product is calcined at 550-650 deg.C which is the calcination temp. when kaolin is used as the raw material. The calcined molded product is humidified, and aged in an aq. soln. contg. 1.6-3.0mol/l NaOH to convert kaolin clay to 100% zeolite. The binderless zeolite molded product is obtained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a binderless 4A type zeolite molded body.

The binderless 4A type zeolite molded body is a useful adsorbent for adsorption, separation and purification. Further, by performing calcium ion exchange treatment to form 5A type zeolite, it has excellent performance as an adsorbent for separating oxygen and nitrogen in the air.

[Prior Art] Various methods have been proposed for producing binderless zeolite molded bodies.

For example, JP-A-57-122932 discloses that a mixture of synthetic zeolite metakaolin clay sodium hydroxide aqueous solution is prepared, the mixture is kneaded, extrusion molded to form a molded body, and the molded body is aged. , a method is disclosed which consists of crystallizing a zeolite molded body by treatment with a dilute sodium hydroxide solution at a temperature of Since the clay in the molded body is used as a clay material, there is no need for a step of firing the clay in the molded body, and the molded body deteriorates in an aqueous sodium hydroxide solution at an elevated temperature, and is finally fired to form a occupancy. - r Cedarless Zeolite 1 - The mechanical strength of the molded product is a low value.

Furthermore, since the amount of clay in the molded body is as high as 40 to 60% by weight, it is difficult to obtain a binderless zeolite molded body with a high zeolite purity.

U.S. Pat. No. 311-9659 discloses a binder made by reacting a highly reactive kaolin clay with sodium hydroxide to form a pre-shaped body, which is further reacted with sodium hydroxide. A method for producing less zeolite is disclosed.

Furthermore, a method is exemplified which consists of adding a small amount of shaped zeolite to the clay. However, this method not only requires a considerable amount of time for the digestion and crystallization steps, but also reduces the water content to about 30% before further treatment of the extrudates with aqueous sodium hydroxide solution.
It is necessary to dry it as follows. In addition, since there is a large amount of clay compared to the zeolite added, the zeolite pure content is +
It is difficult to obtain a binderless zeolite molded body with a height of 4'4i.

Furthermore, in Japanese Patent Publication No. 43-9658, kaolin clay and finely divided sodium aqueous solution hA 33~
After making a mixture with 67% and mixing in four barrels for a long time in the first and second stages, it was molded and
A process for producing a binderless zeolite is disclosed, which comprises converting kaolin clay into metakaolin clay by firing at 0'C and treating the compact with an aqueous medium containing an alkali metal at elevated temperature.

However, according to this method, the molded body mixture does not contain an alkali source for converting kaolin clay into zeolite, and the reaction rate in the next step of treating with an aqueous medium is slow. For this reason, ace and crystallization require a long time. Or a binderless zeolite molded body with a relatively large amount of kaolin clay and high zeolite purity? 1 is difficult to do.

[Problem to be solved by the invention] Binderless zeolite produced by conventional methods uses fired clay that is highly reactive, and as a result, the mechanical strength of the resulting molded product is low. Ta. In addition, the manufacturing process was quite advanced, and since fired clay was used, there were drawbacks such as poor extrusion moldability.

Furthermore, even when raw clay with low reactivity is used, the manufacturing process is quite complicated, making it difficult to produce molded bodies with high zeolite purity. 11 things were difficult.

1] The object of the present invention is a binderless 4A zeolite molded product that contains a higher 4A zeolite purity than conventional methods, that is, has a small inert binder content, excellent mechanical strength, and high adsorption capacity. We present a method for manufacturing (''(
It's about doing.

[Means and effects for solving the problem] Contains high zeolite purity and has excellent mechanical strength] 11 Factors for making a molded body include the type of clay, the mixture of zeolite, clay, and sodium hydroxide.1. Possible factors include q-coupling, firing conditions, etc.

As a result of careful study of these factors, the present inventors have discovered a method of producing a molded body with improved performance through relatively simpler steps and operations than in the past.

The gist of the present invention is a synthetic 4A type zeolite powder, the synthetic 4A type zeolite powder,
20-30% of melon based on the total amount with A-type zeolite powder
A mixture consisting of kaolin-type clay and sodium hydroxide in an amount of 25% or less of the stoichiometric amount for converting the kaolin-type clay into 4A-type zeolite is pressed and molded to 5JIL,
After firing the obtained molded body, the density is 1.6 to 3.0 m.
Binderless 4A, consisting of converting clay to type 4A zeolite in ol/β aqueous sodium hydroxide solution.
There is a method for producing a molded zeolite body, and the details thereof will be explained below.

The zeolite used in the present invention is a type 4A synthetic zeolite which is synthetically produced by known methods, ie from sodium aluminate and sodium silicate.

First, a mixture consisting of 4A type synthetic zeolite, the above amounts of kaolin type clay, and sodium hydroxide was pressed in a press 111.
After adjusting the moisture content so that it can be molded, and adding a lubricant to reduce the extrusion power during IJIL molding, the mixture is kneaded so that it is uniform.

The amount of kaolin type clay and the above Ceorai I.
11, female, J and 20% by weight/lY'j,
I can't replace the product with sufficient strength. On the other hand, 30f
I! If the amount exceeds this amount, it becomes difficult to obtain a molded article with a high zeolite purity content, and the performance deteriorates. Also, if the amount of sodium hydroxide exceeds 25% of the stoichiometric amount for converting kaolin type clay into 4A type zeolite, the tendency of sodalite to generate impurities will increase and the quality of the product will deteriorate. I will do it.

The mixture obtained by kneading is extruded and molded using a known extruder. The obtained molded product is preferably dried by a conventional method at 100 to 120° C. until the moisture content in the molded product becomes about 20% by weight before the next firing.

The dried compact is sized into pellets with a length of 5 to 15 mm, for example, and then fired in an atmosphere 11 at 550 to 650°C, which is the firing temperature when kaolin is used as a raw material.

A baking time of 2 hours is sufficient. By firing under such conditions, the kaolin type clay is sintered to become metakaolin type clay, which strongly binds the zeolite 11-product. All the organic matter in the viscosity 1 will burn and disappear. In addition, all the lubricant of the extrusion aid is burned away, and impurities that are not converted into zeolite at this stage can be virtually ignored.

Next, at least 20% by weight of the fired extruded body
Humidify the water to a level above, and if possible, immerse it in water with 'fA'/M.
However, the gas such as air sucked in through the pores may be desorbed. This operation is not essential for the present invention, but is preferable in order to eliminate the possibility that the molded product will crack or break during the subsequent treatment with an aqueous sodium hydroxide solution.

After pressing for 14"l and humidifying the molded body, dissolve it in water with sodium hydroxide.The temperature of the icing has almost no effect in the range from the normal room temperature to 40'C, and if the temperature is within this range, fine temperature control is required. I don't.

Furthermore, the aging time is short enough if the aging is performed for one hour or more. This is due to the impurities being eliminated during the previous firing, and the kaolin clay in the molded body is substantially reduced to 1.
00% indicates a transition to a reactive metakaolin clay that can be converted to zeolite.

Next, the extrudate containing the aged metakaolin clay binder was immersed in a sodium hydroxide aqueous solution, which was heated to 80°C or higher and below the boiling point using a conventional method to completely remove the metakaolin clay binder in the extrudate. It is converted into type 4A zeolite. However, when considering industrial production, a lower temperature, ie, 80°C, is advantageous. Also, if 2 hours have passed after raising the temperature, it will be 100% Zeolite!・Transforms into

The concentration of the above sodium hydroxide aqueous solution was 1.13m.

If it is lower than /, it takes a long time to convert to zeolite, resulting in poor productivity. The concentration of lf & 3.0 m
ol/j! If the temperature is higher, impurities such as sodalite are produced, resulting in an extruded product having a low purity of type 4A zeolite, which is not preferable.

The extruded product which has been substantially 100% converted to zeolite as described above is taken out from the aqueous sodium hydroxide solution, the excess sodium hydroxide is thoroughly washed with water, and the product is dried. In order to activate it, the product obtained by this drying may be further fired.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, (1) kaolin type clay can be converted into 4A type zeolite in a short time by simple process operations; 2) Binderless 4A that maintains excellent mechanical strength and (3) contains high zeolite purity.
Zeolite extrusion molded body? I can only say 1 no. (4) The completely crystallized extrusion molded body is washed, treated with an aqueous calcium chloride solution at an elevated temperature to exchange sodium and lium ions with calcium ions, and then washed to remove excess calcium. By drying and calcining it to make it t-occupied, a calcium-exchanged zeolite extrusion molded body with a pore size of 5 angstroms and high strength and the same purity is produced. You can also get 1J.

[Example] "Parts" in the following specific examples are by weight.

Example] Type 4A Theorer (1- Mix 100 parts of powder with 25 parts of domestically produced kaolin type clay and 2.26 parts of sodium hydroxide, adjust the moisture content so that it can be extruded with low power, and then extrude. Three parts of CMC (carboquine methyl cellulose) powder was added as an auxiliary agent and the mixture was thoroughly mixed and kneaded in a Fuller mixer so as to be uniform.Next, this kneaded product was extruded into pellets using a twin-screw extruder. After drying at 5 °C
The grains were sized to a length of ~1.5 mm and heated using a Matsufuru furnace at 60 mm.
It was baked for 2 hours in a 0°C atmosphere. After cooling, 200 g of the calcined pellets were immersed in 1 liter of water to defoam, rinsed with 1'J of water, placed in a sodium hydroxide aqueous solution of ], G mol/1, and kneaded at 40'C for 1 hour. The mixture was then left at 80°C for 3 hours to complete crystallization.

Wash this stuff, dry it, and heat it to 350'C.
11-! During the j period, the firing was made special.

Crystallization IJ by X-ray diffraction showed almost complete conversion to type 4A zeolite with no other phases present. The compressive strength of this active product was measured using a Honya type hardness tester and was found to be 5.6 kg. This 11-reinforced product was placed in a tensometer with a relative humidity of 80% for 16+l:r intervals, and the particle strength was measured using the method of JIS-1464, which was 0.4% and 26.5% moisture The amount of adsorption is shown.

Furthermore, when this l:9-modified product was placed in a desiccator with a relative humidity of 8096 for 1611'1, it absorbed 26.5% moisture].
2 I did. This indicates almost complete conversion to type 4A zeolite.

Table 1 Example 2 Extrusion molding was performed in the same manner as in Example], and the fired molded body was immersed in water to defoam, and then 1.9.2.22.5.
Knee zinc in 3.0 mol/j sodium hydroxide aqueous solution lfk at 40°C for 1 hour, and then incubate at 80°C for 3 hours.
The mixture was allowed to stand for a while to complete crystallization. After washing and drying these items, they were activated by firing at 350°C for 1 hour.

Then, in order to confirm complete conversion to type 4A zeolite, crystal analysis was performed by X-ray diffraction, and as a result, no other phases were observed. Furthermore, the compressive strength, particle strength and water adsorption amount at a relative humidity of 8096 were determined.

The results are shown in Table].

1'3 Example 3゜Example 1. Exactly the same procedure was performed except that the molding composition of the extrusion molded body was changed to 100 parts of 4A type zeolite powder, 42.9 parts of domestically produced kaolin type clay, and 3.86 parts of sodium hydroxide, and the physical properties were determined as /III Established. The results are shown in Table 2.

]4 Table 2 '3. I did exactly the same operation.

The physical properties of the obtained product are shown in Tables 3 and 4.

Table 3 (In the case of 25 parts of clay) Example 4 Same as Example 1 except that Joshia kaolin was used as the clay and the amount was changed to 25 parts and then 420 parts to 100 parts of 4A type zeolite powder. and Example] 5 ] Table 4 (In the case of 9 parts of clay 42) Example 5゜Example 2.3. and 4. The Hinderless zeolite molded body obtained in the above was subjected to a calcium ion exchange treatment with an aqueous calcium chloride solution, and then a calcium-exchanged zeolite having a pore size of 5 Ω/m was sealed. After washing and drying it'35
111 at 0°C. Activate firing for -10°C, 7
The nitrogen adsorption amount at 00 torr was determined as A11l. The results are shown in Table 5. Furthermore, the water absorption capacity was determined at 7Ill+ at a relative humidity of 80%.

Table 5] Comparative Example] 4A type Theoler (+- powder 1.0 parts, domestically produced kaolin type clay 1 (30 parts, sodium hydroxide 9 parts) were mixed, the moisture was adjusted, and then CMC powder was added as an extrusion aid. 3 parts were added and thoroughly kneaded in a Mahler mixer so that it became uniform.Then, this kneaded product was treated in exactly the same manner as in Example], and the physical properties were determined.

The results are shown in Table 6.

Table 6 was mixed with C as an extrusion aid while adjusting the moisture content.
3 parts of MC powder was added and kneaded well in a miller grinder to ensure uniformity. Here, the amount of sodium hydroxide combined is 35% of the stoichiometric amount for converting the clay to zeolite. Next, this mixture was prepared in Example 1.
．． It was processed in the same way.

11 ~ Results of crystal solution 4j 〒 carried out by X-ray cycle 1noi,
Other phase Saw Glide was generated. Also, the amount of moisture absorbed at relative 411 degrees and 80% is 230 sol, and 4 A'=
'+ Liseolae I A molded body with low purity was obtained.

Special 11'1 applicant: Tosoh Corporation Comparative example 2

Claims (1)

[Claims] (1) Synthetic 4A type zeolite powder, 20 to 30% by weight of kaolin type clay based on the total of the synthetic 4A type zeolite powder, and a stoichiometric amount of 25% by weight for converting the kaolin type clay into 4A type zeolite. % or less of sodium hydroxide is extrusion molded, the resulting molded body is fired, and then the clay is converted into 4A type zeolite in an aqueous sodium hydroxide solution with a concentration of 1.6 to 3.0 mol/l. A method for producing a binderless 4A type zeolite molded body, characterized by