JP3172346B2 - Manufacturing method of adsorption molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an adsorption molded article for adsorbing and removing odorous substances.

[0002]

2. Description of the Related Art Generally, adsorbents for adsorbing and removing odorous substances are often in the form of powder or granules, and are practically used as molded articles such as pellets and honeycombs. In many cases, these adsorbents are inorganic porous materials, which themselves have poor moldability and low strength. Although it is conceivable to fire the molded body for the purpose of increasing the strength, the inorganic porous material has a property that its specific surface area is greatly reduced when the firing temperature is increased. For this reason, a binder is generally used. For example, starch and lignin are typical examples.

Recently, as a method for producing an adsorption molded article, activated carbon and attapulgite as a clay mineral having a double-chain structure are mixed with a vortex mixer, water is added and kneaded, and the mixture is formed into pellets by an extruder and dried. Thereafter, a method of producing the adsorbed molded body by firing at 500 ° C. in an electric furnace has been proposed (JP-A-4-122439).

[0004]

[Problem to be solved] However, at this firing temperature, there is not sufficient water resistance, and the adsorbed molded article cannot be used during use.
Swelling and shape loss occur due to water adhesion and water immersion. Of course, the molded body formed by the binder without being fired has almost no water resistance.

[0005] By the way, the adsorption molded article is often used as a deodorizing filter for a long time. The problem here is clogging by dust from the environment. If this can be easily washed with water, it can always be used in a high-performance state. In addition, there are many places where these are used, such as toilets, kitchens, bathrooms, etc., near water, and there is a possibility that water may be accidentally applied. For this reason, water resistance is required especially when used as a deodorizing filter.

Further, in order to impart a chemical adsorption ability to these, it is necessary to impregnate a chemical. The attachment is performed after firing the molded body. In this case, generally, a predetermined amount of the above-mentioned agent is applied by spraying, dipping, or the like. for that reason,
Also in this case, the adsorption molded article is required to have water resistance. Further, since the adsorption molded article is used for a long period of time, it is required to have a strength for maintaining the shape in a shape such as a pellet. The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a method for producing an adsorption molded article having excellent water resistance and strength.

[0007]

According to the present invention, there is provided an adsorbent raw material comprising a double-chain structure type clay mineral, or an auxiliary material of at least one of activated carbon, silica gel, alumina gel and zeolite. Adsorbent raw material consisting of
A step of wet-kneading a molding aid to obtain a kneaded product; a step of forming the kneaded product to obtain a molded product;
And baking at 800 ° C.

[0008] As the double-chain structure type clay mineral, for example, sepiolite, palygorskite, and attapulgite can be used. Its composition is that sepiolite is Si ₁₂ Mg _{8
O 30 (OH 2) 4 ·} 8H 2 O, attapulgite and palygorskite _{(MgAl) 5 (SiAl) 8} O 20
(OH) containing a hydrated magnesium silicate of the ₂ · 8H ₂ O. The double-chain structure type clay mineral is a clay mineral containing these hydrous magnesium silicate as a main component and having highly reactive hydroxyl groups on its surface.

Further, as the adsorbent material, a material composed of a clay mineral having a double-chain structure and at least one kind of auxiliary material selected from activated carbon, silica gel, alumina gel, and zeolite can be used. In this case, the content of the double-chain structure type clay mineral is not particularly limited, but it is preferable that the content is 65% to 100% in the raw material of the adsorbent from the viewpoint of the cost of the molded product and the strength.

The molding aid acts in a direction that impairs the adsorption performance of the molded article. Therefore, it is desirable not to use them as much as possible. However, those having complicated shapes such as honeycombs are quite difficult to form without a molding aid. Therefore, in this case, for example, methyl cellulose or the like is used as a molding aid.

The amount of addition is preferably 10 to 20 parts by weight based on 100 parts by weight of the adsorbent raw material. Thereby, good formability is obtained. Further, it is almost decomposed by heating at 550 ° C. or more, and does not adversely affect the adsorption performance of the molded body. Further, the strength and the water resistance of the molded body can be further improved by using together with a binder such as colloidal silica and sodium silicate.

[0012] Next, in the production of the adsorbent molded body, first, at least one of the raw materials of the double-chained clay mineral, activated carbon, silica gel, alumina gel and zeolite.
The uniform mixing of the seed with the seed is an essential condition for improving the performance of the adsorbed molded article after molding at the time of molding. Thereby, smooth molding and a uniform molded body can be obtained. As a mixing device, a Henschel mixer or the like is used for mixing for several minutes.

At this time, the number of rotations of the mixer and the time are determined so as to suppress heat generation as much as possible. Care must be taken especially when methylcellulose is used as an auxiliary agent. Empirically, the preferred conditions are a rotation speed of 400 to 600 rpm and 3 to 5 minutes. Mixing under the condition of a large amount of generated heat causes deterioration of the molding aid and adversely affects the moldability.

In the wet kneading, water is added and kneaded so that uniformly mixed raw materials can be easily formed. In general, when stiffening is performed, moldability is poor, but handling of the molded body after molding,
Handling is easy. On the other hand, in the soft kneading, the moldability is improved but the handling becomes difficult. For this reason, the degree of kneading is determined by the individual molded bodies. Pressing, extrusion, or the like is used as a molding method. The shape of the molded body includes a spherical shape, a pellet shape, a honeycomb shape and the like.

After molding, the compact contains a large amount of water. Therefore, if this product is directly placed in a furnace at a firing temperature of 550 ° C. or higher, the molded product may be cracked or deformed due to the expansion of water caused by a rapid temperature rise. For this reason, it is desirable to perform drying and drying relatively slowly before baking. For that purpose, dielectric heating, in which a temperature gradient is hardly generated inside the molded body, is suitable. The conditions for the induction heating are preferably such that the molded body is kept at a temperature of about 110 ° C. The process from drying to baking can be continuous or batch.

It is preferable that the moisture content in the molded body before firing is 5 to 10%. Thereby, damage during firing can be prevented. The dried body is heated so as to reach a predetermined firing temperature after several hours, avoiding a rapid rise in temperature. After reaching the predetermined temperature, firing is performed for several hours, followed by furnace cooling or natural cooling. When activated carbon is used as one of the adsorbent raw materials, it is necessary to set the inside of the furnace to a reducing atmosphere or an inert atmosphere.

The firing temperature of the compact is 550 ° C. to 8 ° C.
The temperature must be set to 00 ° C. That is, the double-chain structure type clay mineral has dry consolidation properties. When the dried and solidified material is heated, a phase change is expected little by little, and finally a phenomenon called sintering occurs. Then, in a sintered body that completely undergoes a phase change, its adsorption performance is lost. Therefore, firing is performed in a temperature range of 550 ° C. to 800 ° C., which is pseudo sintering.

[0018] The adsorption molded article obtained by the present invention includes a toilet, a refrigerator, a cooker, an indoor air purifier, a vehicle interior deodorizer,
It can be used as a deodorizing filter in various fields such as exhaust gas purification.

[0019]

In the adsorption molded article of the present invention, the clay mineral having a double-chain structure has sinterability as described above.
The concept of sintering is to minimize the surface energy where the crystals overlap. When energy is applied from the outside, electrons are transferred or fused at these contact points, and sintering proceeds.

For example, it is known that sepiolite, which is a clay mineral having a double-chain structure, undergoes a phase change from 550 ° C. to form a metasepiolite phase. Due to the phase change, electrons are transferred during this period, and sintering proceeds partially.
Further, at 830 ° C., a crystal phase of steatite appears, which is no longer a porous sepiolite but is strongly sintered. Therefore, as described above, the firing is performed at 800 ° C. or less.

When the composition is formed at a temperature of 550 ° C. or more at which partial sintering starts, the bonding between sepiolite fibers proceeds,
Even when immersed in water, it does not disperse for each fiber and improves water resistance. In addition, the sintering also increases the strength of the suction molded body. The same applies to the case where only the double-chain structure type clay mineral is used as the adsorbent raw material and the case where the double-chain structure type clay mineral and auxiliary raw materials such as activated carbon are used as the adsorbent raw material. As is known from the above, according to the present invention, it is possible to provide a method for producing an adsorption molded article having excellent water resistance and strength.

[0022]

EXAMPLES A method for producing an adsorption molded article according to the present invention will be described. First, an adsorbent material comprising 67 parts by weight of sepiolite as a clay mineral having a double-chain structure and 33 parts by weight of activated carbon as an auxiliary material was prepared. In contrast, 17 parts by weight of metroze as a forming aid and 164 parts of water were prepared. Parts by weight were added and mixed with a Henschel mixer. Further, after kneading with a kneading machine, it was formed into a honeycomb shape by an extruder. After molding, and after day and night training, primary drying was performed using a microwave oven. This was further dried at 110 ° C. for 2 hours with a hot air drier and then fired. The atmosphere during the drying and firing was a nitrogen gas atmosphere.

In the above treatment, the sintering temperature is set to 320 to
At various temperatures of 750 ° C. (Table 1), adsorption molded articles were produced. Then, the water resistance and strength of each adsorption molded body were measured. Table 1 shows the measurement results of each sintering temperature, the water resistance of the adsorptive molded body, and the honeycomb crushing strength. Water resistance is
The measurement was carried out for 30 minutes in water, and the external shape was evaluated.

The honeycomb crushing strength is represented by the load obtained by the measuring method shown in FIG. That is, the suction molded body 1 formed into a honeycomb shape is placed on the plate 2 and a load is applied by the loader 3 via the load plate 31. Then, the suction molding 1
Table 1 shows the load at the time of fracture. The load plate was 20 × 20 mm.

[0025]

[Table 1]

As can be seen from Table 1, the firing temperature is 40
Below 0 ° C., the adsorptive molded body lost its shape in water. Although swelling was observed at 500 ° C., the shape of the adsorption molded article was maintained. Further, the strength (load) is 2.8 kg at 500 ° C. or higher, and the strength is further improved at a firing temperature higher than 500 ° C. However, below 400 ° C., the strength is low. In the case where the firing temperature is 850 ° C., there is no problem in water resistance and strength, but the specific surface area is about 1/3 as compared with that before firing, and there is a problem in the deodorizing performance of the adsorption molded article. On the other hand, if the firing temperature is 550
C., 650.degree. C., and 750.degree. C., the specific surface area was about 2/3 of that before firing.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a crushing strength test in an example.

[Explanation of symbols]

 1. . . 2. Adsorption molded body, . . Loading machine,

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsumasa Horii 41-1 Chuchu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central Research Laboratory Co., Ltd. (72) Inventor Shozo Tsuji 1780 Nagaoka, Yamato-cho, Sakata-gun, Shiga Prefecture Address Omi Mining Co., Ltd. (72) Inventor Kazuki Tanabe 1780 Nagaoka, Yamato-cho, Sakata-gun, Shiga Prefecture Inside Omi Mining Co., Ltd. (56) References JP-A-5-64745 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) B01J 20/00-20/34

Claims (2)

(57) [Claims] 1. An adsorbent material comprising a double-chain structure type clay mineral, or an adsorbent material comprising said double-chain structure type clay mineral and at least one kind of auxiliary material of activated carbon, silica gel, alumina gel and zeolite A step of wet-kneading the raw materials and a molding aid to obtain a kneaded product, and forming the kneaded product;
A method for producing an adsorption molded article, comprising: a step of obtaining a molded article; and a step of firing the molded article at 550 to 800 ° C. 2. The method according to claim 1, wherein when the activated carbon is used, the molded body is fired in a reducing atmosphere or an inert atmosphere.