JPH0492811A - Cellular sepiolite substance, its production and adsorptive decomposition catalyst using the same - Google Patents

Abstract

PURPOSE:To obtain a cellular sepiolite substance excellent in adsorption performance and characteristics as a catalyst carrier by pulverizing sepiolite, conditioning moisture thereof, then forming the conditioned sepiolite, burning the formed compact at a specific temperature and subsequently washing the burned compact with an acid. CONSTITUTION:Sepiolite is pulverized and moisture thereof is conditioned. The resultant powder is then formed and the resultant formed compact is burned at a temperature within the range of about 650-800 deg.C. The burned sepiolite compact is subsequently washed with an acid to afford the objective cellular substance. The aforementioned cellular substance is a cellular sepiolite substance in which pores having <=50Angstrom pore diameter have 40-200m<2>/g specific surface area and account for >=20% of the whole surface area with a pore distribution curve having main peaks at positions of the pore diameter of <=50Angstrom . The above- mentioned cellular substance has excellent adsorption performance and characteristics of physical strength and is useful as a catalyst for adsorbing and removing malodor in refrigerators by supporting a catalytic component thereon.

Description

[Detailed description of the invention] [Technical field] The present invention is characterized in that pores with a pore diameter of 50 Å or less account for 20% of the total surface area.
The present invention relates to a sepiolite porous body with excellent adsorption properties as described above, a method for producing the same, and an adsorption decomposition catalyst in which a catalyst component is supported on the sepiolite porous body.

[Prior art]

Attempts to manufacture porous molded bodies using sepiolite as a raw material were made in Japanese Patent Publication No. 55-31085 and Japanese Patent Publication No. 59-1.
This method has been proposed in Publication No. 8321 and the like.

In other words, the above-mentioned Japanese Patent Publication No. 55-31085 states, ``The main component is sepiolite, the specific surface area is 200d1g or more, and 100rrr/g or more of which has a pore diameter of 74Å.
It is a part composed of the above pores, and the pore diameter is 74
The pore volume is 0.5 to 1.0 cc/g, and the pore size is 20'o for the pore volume of 74 Å or more.
~600 A sepiolite molded body effective as a heat insulating material, a sound absorbing material, an adsorbent, and a catalyst carrier, characterized in that the ratio of 3° pore volume is 60% or more. '' is disclosed, and its manufacturing method is ``a method of forming a porous body using sepiolite as a raw material, (a) a step of pulverizing sepiolite and then adding water to adjust the humidity; (b) !p1 wet material. "A method for producing a Seviolite molded body characterized by comprising the steps of sufficiently kneading: and (c) molding and firing the mixed wire material." is proposed.

Further, Japanese Patent Publication No. 59-18321 states that it was observed that the pore volume and specific surface area of natural sepiolite were significantly increased by acid treatment.

The present inventors have succeeded in creating ultra-large pores of 1000 Å or more to the same extent as natural products by firing the moisture-conditioned product at a temperature range of about 650°C to 800°C without adopting a process of thoroughly kneading it. We discovered that it is possible to obtain a Seviolite molded product that does not peptize even when immersed in water, has excellent water resistance, and is resistant to heat shock. However, it has not been possible to increase the specific surface area of pores having a pore diameter of 50 Å or less, which is effective for adsorption ability.

By the way, the aforementioned Japanese Patent Publication No. 59-18321 discloses a modified sepiolite which is produced by chemical means, that is, by reacting a magnesium desorbing agent with natural sepiolite to eliminate its framework magnesium, and which is extremely porous compared to natural sepiolite. It is described that it is effective as a catalyst for the hydrogenation reaction of heavy oil, especially for the hydrodemetalization reaction of heavy oil. There is no mention of it. Furthermore, there is no suggestion at all of an adsorption-decomposition catalyst that focuses on this excellent adsorption property.

[Problems to be solved by the present invention]

As mentioned above, the sepiolite porous material has pores with a pore diameter of 50 Å or less that have a large specific surface area, which is not found in conventional sepiolite porous materials, and has excellent adsorption performance, and also has extremely excellent properties as a catalyst carrier. The purpose is to provide

[Means and effects for solving the problem] The specific surface area of natural sepiolite is 400rrf/g or less, and 3
The specific surface area of the product fired at a temperature of 00°C is 200n (/
The specific surface area of those fired in the temperature range of 500'C to 800'C ranges from 200 Bo/g to 120 Bo/g.
It is a well-known fact that when fired at a temperature of 800°C or higher, it transforms into steatite, which increases brittleness and decreases strength as the specific surface area decreases. However, natural sepiolite fired at a temperature range of 300°C to 800°C changes to metasepiolite, the 5-10 crystal structure peculiar to sepiolite collapses, the degree of crystallinity decreases, and the surface area also decreases.
Furthermore, crystal fiber bundles (0.2-2 μm!%, 100-30
Although the crystal structure of the 5 to 10 layers is not completely destroyed and the pores are blocked due to dehydration etc., the crystal structure of the 5 to 10 layers is not completely destroyed. It is in a collapsed state.

Appropriate acid washing restores this crushed crystal structure, and by restoring the zeolitic pores of less than 50 Å, which contribute to adsorption capacity, the surface area increases, and X-ray diffraction shows that the crystal structure is close to that of natural sepiolite. It was confirmed that the crystal structure had been restored to the normal state.

As a result of intensive research based on the above knowledge, the inventors of the present invention molded sepiolite after pulverizing and controlling its humidity.
By firing at a temperature range of 50°C to 800°C and washing the fired sepiolite with acid, pores with a pore diameter of 50 Å or less have a specific surface area of 40 to 200 m2/g and 2 of the total surface area.
We have discovered that it is possible to produce a sepiolite porous material that accounts for 0% or more, and have completed a catalyst for adsorption and removal of bad odors from refrigerators by supporting catalyst components, paying attention to its excellent adsorption performance and physical strength characteristics.

The catalyst component decomposes and removes malodorous or harmful components when heated, and is a type selected from the group consisting of platinum group metals, manganese, iron, copper, cobalt, nickel, silver, and rare earth metals such as cerium and lanthanum. metals, oxides or composites of the elements. Among the above elements, platinum group metals, especially platinum or platinum-palladium, are preferred;
Furthermore, it is preferable to use a rare earth metal, particularly cerium or lanthanum, in the catalyst component, since this further improves the heat resistance of the catalyst.

The catalyst components can be supported by conventional methods.

The amount of platinum group metal supported is 0.5 to 5 g/Ω, preferably 1
~2gIQ, and the amount of rare earth metal supported is 1~100
g/fi, preferably 5-20 g/Q.

A preferred method for producing the sepiolite porous body of the present invention is illustrated below.

Less than 100 meshes of sepiolite, preferably 150 meshes
Grind the sepiolite powder to a mesh size or less, add water to the sepiolite powder, and adjust the water content of the sepiolite powder after adding water to 4O-20 (h
t%, preferably adjusted to 45 to 55 vt%. In addition to a portion of water, a water-soluble oxygen-containing compound such as alcohol, ester, ether, ketone, acetone, or nitrile can be used for humidity control. When stirring and mixing the water-added sepiolite powder to uniformly control the humidity, care must be taken to avoid crosstalk.

In the technique disclosed in Japanese Patent Publication No. 55-31085, thorough kneading is considered important, but in the present invention, not kneading before molding, combined with acid washing after firing, is This is important for obtaining the porous sepiolite material having the unique physical properties of the invention.

The conditioned sepiolite powder is molded into an arbitrary shape, for example by pressure, and the molded body is dried at a temperature of 100°C to 150°C, and then heated to a temperature of about 650°C to 800°C, preferably 700°C.
After firing at ~800°C, particularly preferably at 720°C ~ 770°C to obtain a sepiolite porous body having a crystal structure in the metasepiolite region, the fired product is washed with an acid such as nitric acid, sulfuric acid, or hydrochloric acid, washed with water, and dried. A sepiolite porous body was obtained.

Example 1 10 kg of high-purity sepiolite from Turkey with a water content of 17 wt% (sepiolite purity of 92% or more) was ground and mixed well with a mortar mixer.

Add water at a ratio of 6 kg to 10 kg of crushed sepiolite, and stir and mix well by hand so as not to knead in the container to uniformly control the humidity. Further, the moisture-adjusted sepiolite was passed through a 100 mesh screen to obtain a powder whose particle size was adjusted to 100 mesh or less. The sepiolite powder was pressure-molded to obtain a sepiolite plate.

The obtained sepiolite plate was dried at a temperature of 120°C for 12 hours, and then fired at a firing temperature of 740°C for 3 hours.
A 4+m×18×6m sepiolite porous body a was obtained.

The obtained sepiolite porous body a was further immersed in a 1% nitric acid solution kept at a temperature of 50° C. for 1 hour, and then washed with water to obtain a sepiolite porous body.

Example 2 Sepiolite porous body C was prepared in the same manner as in Example 1 except that it was immersed in a 1% nitric acid solution kept at a temperature of 50°C for 2 hours.
I got it.

The properties of the obtained sepiolite porous bodies a, b and C were investigated and found to be as follows.

(Left below) 50kg/ffl pressure 54m x 18m x 6
wm (7) Regarding the press-formed Seviolite plate-like material, the strength at 45-foot intervals t Seviolite porous body a Seviolite porous Th
Sepiolite porous material C1.3kg
1.5 kg 1.5 kg The bending strength was measured using the apparatus shown in FIG. That is, support pieces 12 each having a radius of curvature of 5 m at the tip are placed on the base 11 at intervals of 45 cm, and a test piece 14 is placed thereon, and a load is applied to the support piece 12 whose tip has the same radius of curvature as the support piece. The load (kg) at the time of fracture of the test piece 14 was defined as the bending strength.

Figures 1 to 3 show the pore distribution of Seviolite porous materials a, b, and C obtained by the BJH method (nitrogen desorption method).

From Figures 1 to 3, there is a main peak at a pore diameter of 50 Å or less in the porous sepiolite materials S and C treated with nitric acid, and pores with a pore diameter of 50 Å or less are developed by the acid treatment. It is recognized that

Comparative Example 1 Seviolite molded body d was obtained in the same manner as in Example 1 except that the firing temperature was 500°C.

When the obtained sepiolite molded body d was treated with nitric acid in the same manner as in Example 1, the sepiolite molded body d was peptized and became crumbly, so that a molded body with practical strength could not be obtained.

Example 3 Thirty-six sheets each of sepiolite porous bodies a and b obtained in Example 1 and sepiolite porous body C obtained in Example 2 were added to a hexane ammine platinum OV) chloride solution (1
, 463% pt content) 0.74 g of 28% ammonia water (manufactured by Wako Pure Chemical Industries, Ltd.) was added to 5.13 mm, the pH was adjusted to 10.5, and the sample was immersed in a solution diluted to 340 mQ. washing with water,
After drying, it is reduced at a temperature of 500°C in a hydrogen stream, and pt
Adsorption and decomposition catalysts a, b, and C carrying platinum in an amount of 1.47 g/Q were obtained.

Test Example 1 Trimethylamine reaction test The obtained adsorption and decomposition catalysts a, b, and C were placed in a 16Q glass reaction tank, and trimethylamine was injected so that the concentration in the tank was 3000 ppm, and the mixture was left at room temperature for 30 minutes. The surface temperature of the adsorption decomposition catalyst was heated to 350° C. for 15 minutes, and the mixture was allowed to cool for another 25 minutes, and the change in trimethylamine concentration was measured. The results are shown in FIG.

Incidentally, the residual rate (%) was determined by the following relational expression between the initial concentration CO and the concentration Ct over time.

Residual rate (%) = Ct/Co .

Example 4 The adsorption and decomposition catalysts obtained in Example 3 and C were installed near a defrosting heater in the cooling air circulation path of a refrigerator of forced cooling air circulation type.

During the cooling operation of the refrigerator, the air inside the refrigerator is circulated by the fan through the circulation path, and the malodorous gas generated from the stored food is adsorbed and removed by the adsorption/decomposition catalyst, thereby deodorizing the inside of the refrigerator. When frost builds up on the cooler and cooling performance deteriorates, the defrost heater automatically activates. At this time, the adsorption and decomposition catalyst is heated by using the heat of the defrosting heater, the occluded malodorous gas is desorbed and the adsorption capacity is regenerated, and the desorbed malodorous gas is oxidized to the adsorption and decomposition catalyst The process gas is purified by oxidative decomposition using a catalyst.

At this time, the adsorption and decomposition catalyst is repeatedly frozen and heated under conditions in which a large amount of water is attached or adsorbed. However, the adsorption and decomposition catalyst according to the present invention has excellent heat shock resistance without causing freeze failure. It exhibited excellent deodorizing ability through adsorption and decomposition of malodorous gases without becoming brittle.

〔effect〕

The Seviolite porous material of the present invention has a large specific surface area of pores with a pore diameter of 50 Å or less, has an extremely high adsorption capacity, and has excellent heat shock resistance, non-freezing strength, and non-deflocculation against water. Therefore, it is suitable for harsh environments where temperature changes are large and it is easy to get wet with water, so it has extremely excellent characteristics as a catalyst support for removing malodors and adsorbing particles in cold storages.

[Brief explanation of the drawing]

1 to 3 are graphs showing pore distribution. FIG. 4 is a graph showing the residual rate of trimethylamine. FIG. 5 is a reference diagram showing an apparatus for testing bending strength. Patent Applicant Hide Tomo Matsu, Patent Attorney for JGC Universal Co., Ltd. Illustration 1 Figure 2 Shoulder Hole Diameter (Al #fl Hole Monster (λ) X v/r Figure 3 Shaft Hole Diameter (Vision Figure 4 Figure 5 Procedure Relationship between the written amendment case and the person who amends the labeling case

Claims (1)

[Claims] 1. Pores with a pore diameter of 50 Å or less are 40 to 200 m^2/
A sepiolite porous material having a specific surface area of 1.5 g, accounting for 20% or more of the total surface area, and having a pore distribution curve having a main peak at a pore diameter of 50 Å or less. 2. Crush sepiolite, adjust the humidity, and then mold it to about 650 yen.
A method for producing a porous sepiolite body, which comprises firing at a temperature range of 800°C to 800°C, and washing the fired sepiolite with an acid. 3. Pores with a pore diameter of 50 Å or less are 40 to 200 m^2/
The catalyst component is supported on a sepiolite porous body which has a specific surface area of 1.5 g, occupies 20% or more of the total surface area, and whose pore distribution curve has a main peak at a pore diameter of 50 Å or less. Adsorption decomposition catalyst. 4. An adsorption and decomposition catalyst characterized in that it is used as a catalyst for adsorption and decomposition removal of bad odors in refrigerators.