JPH0871425A - Ozone decomposition catalyst - Google Patents

Abstract

PURPOSE: To obtain a high performance ozone decomposition catalyst with a low-cost carbon material by mixing porous carbon particles contg. a transition metal and having a specified BET specific surface area with pseudo-boehmite type alumina hydrate in a specified ratio and further mixing the resultant mixture with a specified percentage of a smectite family clay mineral or zeolite. CONSTITUTION: This ozone decomposition catalyst contains porous carbon particles contg. a transition metal and having 5-50m<2> /g BET specific surface area and pseudo-boehmite type alumina hydrate in a weight ratio of 1:1.4 to 2:1 and further contains 10-30wt.% synthetic or natural smectite family clay mineral or synthetic or natural zeolite. The porous carbon preferably contains 1-20wt.% at least one kind of transition metal selected from among Fe, Ni, Co and V. The porous carbon is easily available as heavy oil soot or crude oil soot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an economical ozone decomposition catalyst, and more particularly to an ozone decomposition catalyst using a composition of porous carbon particles, hydrated alumina and smectite or zeolite. Is.

[0002]

2. Description of the Related Art Ozone has an excellent oxidizing power,
It is widely used in the fields of deodorization, sterilization, decolorization, decomposition of cyan and other organic substances. However, since ozone is harmful to the human body, it is necessary to decompose excess ozone used for these treatments before releasing it into the atmosphere. In addition, O of copier, printer, fax machine
Equipment A, dust collectors, air purifiers, etc. utilize corona discharge and also generate ozone, so that ozone decomposition processing is also required.

Conventionally, activated carbon or a catalyst having activated carbon as a carrier has been widely used for the decomposition treatment of ozone. For example, in Japanese Patent Laid-Open No. 4040464, activated carbon was used as a carrier to support manganese. Ozone decomposition catalysts are described. Further, in JP-A-3-242227, 50% by weight or more of activated carbon, 5 to 40% by weight of transition metal oxide, and 5 to 1 of flame retardant components such as ceramics and clay minerals are disclosed.
It is described that a honeycomb molded body containing 5% by weight is used for ozone removal. Furthermore, JP-A-4-108542
The publication describes a catalyst for ozone decomposition in which activated carbon is used as a carrier and nickel oxide is supported as active species on the carrier.

[0004]

The catalytic decomposition method using activated carbon is said to utilize a chemical reaction in which carbon of activated carbon is oxidized by ozone to generate carbon dioxide. However, activated carbon is very expensive. There is a demand for a lower cost catalyst for ozone decomposition. In addition, activated carbon tends to deteriorate with time even if it has excellent initial performance, and there is another problem that the ozone decomposition rate is low under high humidity conditions.

Therefore, an object of the present invention is to provide a high performance ozone decomposition catalyst using an inexpensive carbon material, which is different from the conventional activated carbon. Another object of the present invention is to provide an ozone decomposition catalyst that has a low catalyst cost, has a stable decomposition activity for a long time, and can easily replace the catalyst when the activity decreases.

[0006]

According to the present invention, a transition metal component is contained and a BET specific surface area of 5 to 50 m ² /
g of porous carbon particles and pseudo-boehmite hydrated alumina in a weight ratio of 1: 1.4 to 2: 1 and 10 to 30% by weight of the total of synthetic or natural smectite group clay There is provided an ozone decomposition catalyst comprising a composition containing a mineral or a synthetic or natural zeolite. The porous carbon used in the catalyst of the present invention preferably contains a transition metal component in an amount of 1 to 20% by weight, and the transition metal component is at least one selected from the group consisting of iron, nickel, cobalt and vanadium. It should consist of a metal component. The porous carbon that is the source of the catalyst of the present invention is not limited to this, but is easily available as heavy oil soot or crude oil soot.

[0007]

The catalyst used in the present invention comprises (a) porous carbon particles, (b) quasi-boehmite-type hydrated alumina and (c) granular molded products of smectite group clay mineral or zeolite. Contains (1) a transition metal component and a sulfur component, and (2) has a BET specific surface area of 5 to 50 m ² / g, particularly 7 to 30 m ² / g.
As a carbon adsorbent, it is a remarkable feature that it is in an exceptionally low range. As shown below, it is a comparison of the specific surface area of activated carbon or activated coke used for the purpose of ozonolysis and the porous carbon used in the present invention, which is an order of magnitude smaller than the conventional one. Indicates.

[0008]

According to the present invention, by combining the specific porous carbon with pseudo-boehmite-type hydrated alumina and a smectite group clay mineral or zeolite in a fixed amount ratio, ozone decomposition performance and durability are remarkably improved. Moreover, when it is made into a granulated product, the mechanical strength and wear resistance of the particles are remarkably improved.

Further, in the present invention, when the porous carbon and / or the granulation medium is irradiated with an electrode, especially a microwave, at any stage before the granulation and after the granulation, ozone decomposing performance as a catalyst is obtained. Was found to improve. this is,
The microwave is an absorption wavelength of water molecules, and it is considered that the porous carbon is activated by the fact that the inside of the porous carbon is uniformly heated by the thermal motion of the microwave.

See the examples below. That is, the catalyst of the present invention (1.5 mmφ, pellets) was packed in a packed column having a length of 9 cm and a volume of 25 ml, and the ozone concentration was 34.5.
When an ozone-containing gas of g / m ³ was passed at a very low speed of 0.5 l / min and the ozone concentration at the outlet was measured, the ozone concentration was 0% even after 10 hours, and the ozone removal rate was 100%.
Therefore, it can be seen that it is extremely excellent in terms of activity of ozonolysis and sustainability of activity.

Since the above-mentioned porous carbon used in the present invention is discharged as a large amount of crude oil soot, heavy oil soot, etc. from a combustion apparatus that uses a fuel such as crude oil or heavy oil, it can be obtained at a significantly low cost, and the environment by disposal It offers the advantage of being reusable for ozonolysis purposes without pollution problems.

In the present invention, when the above-mentioned porous carbon is combined with pseudo-boehmite-type hydrated alumina and synthetic or natural smectite-type clay mineral or synthetic or natural zeolite, the specific surface area of the catalyst is increased and the adsorption capacity is increased. , It also has an auxiliary action to increase ozone decomposition performance. That is, in this composite catalyst used in the present invention, ozone is first adsorbed on the surface of alumina, and then on the porous carbon, the formulas (1) and (2) 2O ₃ → 3O ₂ ... (1) 3C + 2O ₃ → It is recognized that the reaction of 3CO ₂ (2) proceeds. Of course, the smectite and zeolite added to the catalyst and the transition metal component in the porous carbon also contribute to their adsorption and reaction.

Further, the above-mentioned alumina and smectite or zeolite enhances the moldability of this catalyst into a granular molded product and also improves the physical properties of the granular product. That is, the hydrated alumina and the like not only become a granulation medium having excellent workability for molding the porous carbon particles into particles of a predetermined size and a predetermined shape, but also compressive strength of the molded particles and It has an advantageous effect of increasing the abrasion resistance and also the water resistance (wet strength).

[0015]

Preferred Embodiment of the Invention

(Porous carbon) The porous carbon particles used in the present invention include transition metal components, particularly components such as iron, cobalt, nickel and vanadium, generally in the form of oxides in an amount of 1 to 20% by weight, particularly 3 to 12% by weight. %contains. This transition metal component acts as a catalyst for the reactions of the above formulas (1) and (2). The porous carbon particles further include Na,
It contains an alkali metal component such as K and an alkaline earth metal component such as calcium and magnesium, and the amount thereof is generally in the range of 0.1 to 2.0% by weight per particle.

The porous carbon particles used in the present invention preferably contain carbon having a calorific value of 3000 kcal / kg or more. A scanning electron micrograph (300 magnification) of the porous carbon used in the present invention is shown in FIG.
Shown in From this figure, it is understood that the porous carbon of the present invention has so-called pumice-like macropores. BET
The specific surface area determined by the method is 5 to 50 m ² / g, particularly 8 to 30 m ² / g, which is unexpectedly small, and the pore volume determined by the N ₂ adsorption method is 0.01 to 0.05 ml / g, particularly 0.1. 015
To as small as 0.035 ml / g and the pore size is generally 40
It is in the range of 60Å. The particle diameter of the porous carbon is 0.05 to 5 in terms of median diameter by the Coulter counter method.
It is in the range of 0 μm, particularly 0.5 to 30 μm.

This porous carbon can be obtained by sufficiently drying crude oil soot, heavy oil soot, etc. discharged from a power plant, etc., and removing iron rust using a 70-80 mesh screen. Of course, it is not limited to this as long as it has characteristics.

(Catalyst) In the present invention, carbon particles and quasi-boehmite hydrated alumina are mixed in a ratio of 1: 1.4 to 2: 1,
In particular, it is used in a weight ratio of 1: 1 to 1.5: 1. In addition, 10 to 30% by weight, especially 15 to 25% by weight
The synthetic or natural smectite clay mineral or the synthetic or natural zeolite is used in combination.

The hydrated alumina used in the present invention is generally 5
particle size of less than μm, especially less than 3 μm and 200 to 400 m
BET specific surface area of ² / g and 0.3 to 0.6 ml / g
Those having a pore volume of Generally, pseudo-boehmite-type hydrated alumina is produced by reacting sodium aluminate with a mineral acid such as sulfuric acid, or by reacting an aluminum salt such as aluminum sulfate with an alkali such as caustic soda. Hydrated alumina produced by a known general production method that satisfies the above requirements can be used for the purpose of the present invention. Hydrated alumina which is advantageously used for the purpose of the present invention is, for example, Japanese Patent Publication No.
It is manufactured by the method described in Japanese Patent No. 13652 and described in the same publication. The hydrated alumina used as a raw material is represented by the formula (3) Al ₂ O ₃ · xH ₂ O (3) In the formula, x is a number of 1.0 to 2.0, and particularly 1.4 to 1.8. . It is preferable to have a composition of

As the natural or synthetic smectite type clay mineral, dioctahedral type smectites such as montmorillonite, beidellite and nontronite, and trioctahedral type smectites such as saponite, hectorite, sauconite and stevensite can be used. These smectite group clay minerals have adsorbability by themselves, and also have an action as an inorganic binder to improve mechanical strength and wear resistance of a molded product. Particularly preferred are acid clay or activated clay belonging to montmorillonite, synthetic layered magnesium phyllosilicate described in JP-A-61-10020, JP-A-61-100.
21. Synthetic fly pontite described in JP-A No. 21-63, JP-A-63-
Active bentonite described in Japanese Patent No. 50310, Japanese Patent Application No. 62-62
The synthetic stevensite of JP-A-20476 and the like can be mentioned. These clay minerals generally have a particle size of 10 μm or less, particularly 3 μm or less, and 200 to 600 m ² /
It is preferable to have a BET specific surface area of g, especially 200 to 500 m ² / g. Synthetic stevensite, in particular substantially (4) MgxNaySi ₄ O ₁₀ (OH) ₂ · Naz (4) In the formula, x and y are two or more under the condition that x + y <3. , Y is a number from 0 to 0.1, and z is a number from 0 to 1.0. Those having a chemical composition represented by are preferred.

Further, as a synthetic fly-pontite, SiO _{2 is} 5 to 45 mol%, in a three-component composition ratio represented by an oxide.
A microcrystalline synthetic flypontite consisting of zinc phyllosilicate or aluminum-containing zinc phyllosilicate in the range of 35 to 65 mol% ZnO and 0 to 60 mol% Al ₂ O ₃ is preferred.

On the other hand, as the synthetic or natural zeolite, A-type zeolite, Y-type zeolite, X-type zeolite, P-type zeolite, HY-type zeolite, mordenite, clinoptite and the like can be used.

The ozone decomposition catalyst of the present invention can be used in the form of granules or in the form of being supported on a filter or the like.

Granulation of the composition containing porous carbon can be carried out by a method known per se such as an extrusion granulation method, a tableting granulation method, a tumbling granulation method and the like. As a typical example, porous carbon, a granulating medium, other auxiliaries and the like are mixed, and this mixture is kneaded for homogenization in the presence of water and then molded into a predetermined shape. A kneader, a super mixer, a single-screw or twin-screw extruder, etc. can be used for the kneading operation, and a vacuum-type kneader can be used if necessary. For molding the granules, various molding machines known per se, for example, an extrusion molding machine, a tableting machine, a rolling granulator and the like can be used. Generally, the kneading and molding is preferably carried out by an extruder, and the kneading is preferably carried out in at least one stage, preferably in multiple stages. In multi-stage kneading and molding, the particle size of extrusion molding can be gradually reduced.

The granular compact is subjected to a drying treatment at a temperature of 100 to 120 ° C. and then calcined at a temperature of 200 to 400 ° C. Drying at the above temperature prior to calcination is important for obtaining a dense and excellent composite adsorbent, and at a temperature lower than the above range, water is not sufficiently removed. There is a tendency for foaming during calcination, and at temperatures higher than the above range, there is a tendency for foaming during drying due to rapid removal of water. The purpose of calcination is to densify and strengthen the composition by tightening the composition and at the same time to convert quasi-boehmite hydrated alumina into highly active alumina. In addition, in the composite adsorbent of the present invention, the pseudo-boehmite type structure is preserved even after the conversion to high activity alumina. When the temperature of the heat treatment is lower than the above range, the densification due to quenching is insufficient, the conversion into highly active alumina is insufficient, and the durability becomes poor. On the other hand, when the heat treatment temperature is higher than the above range, the surface activity of the adsorbent tends to decrease. The calcination process is generally performed for 60 to 360 minutes, particularly 120 to 240 minutes.
It can be performed by heating for a minute.

The granular molded product used in the present invention can have any shape such as a columnar shape (pellet shape), a tablet shape, and a spherical shape, and the particle size thereof is 0.1 to 10 mm, particularly 0.2 to. It is preferably in the range of 5 mm. Suitable catalysts for use in the present invention are generally 100 to 250
m ² / g, especially BET specific surface area of 120 to 200 m ² / g, 0.1 to 0.35 ml / g, especially 0.2
It has a pore volume of ˜0.3 ml / g.

As described above, in the present invention, the porous carbon particles are irradiated with microwaves before the granulation and at any stage of the particle size, as required. As microwaves, frequencies 1 to 3 G generally used for microwave heating are used.
The range of Hz is good, and the irradiation energy is 1 kg.
The range is preferably 0.8 to 3 w, and the irradiation time may be as short as about 10 to 40 seconds.

The ozone decomposition catalyst of the present invention can be used as a filter for collecting ozone in an OA equipment or an air purifier while being supported by a filter or the like. That is,
Of the above-mentioned granular moldings, one having a fine particle size, for example, one having a particle size of 0.1 to 1 mm is dispersed in a liquid medium containing a binder, and this slurry is used as a continuous vented polyurethane foam sheet and a woven fabric of various fibers. Alternatively, it is applied to a filter made of non-woven fabric or the like to obtain an ozone decomposition catalyst supporting filter. As the binder, polyvinyl alcohol,
Sodium alginate, cellulose derivatives, styrene-butadiene-rubber latex, etc. are used, and this binder is generally used in an amount of 1 to 10 parts by weight per catalyst. The catalyst supported on the filter is preferably a granular material, but of course, a slurry in the form of powder may be supported on the filter.

The ozone decomposition catalyst of the present invention is sterilized, deodorized,
It is effective for decomposing excess ozone used for decolorization, decomposition of organic substances and the like, and for this purpose, treatment is carried out by passing an excess ozone-containing gas through a packed column filled with the ozone decomposition catalyst of the present invention. Since the ozone decomposing catalyst of the present invention is also excellent in deodorizing action on odorous components, there is also an advantage that when the excess ozone-containing gas contains odorous components, deodorization is also performed at the same time. The ozone decomposition catalyst of the present invention is O
It is also useful for capturing and decomposing ozone discharged from the A equipment and air purifier.

The invention is illustrated by the following example.

EXAMPLES The evaluation test in the present invention was carried out by the following method. (1) BET specific surface area automatic BET specific surface area measuring device (CORLO-ERBA Corp. Sorptomatic Series 180
0) was used to determine the nitrogen gas adsorption V _m [cc / g] to be adsorbed on the sample surface by the monomolecular layer, and the specific surface area was determined by the following formula. Specific surface area SA = 4.35 × V _m [m ² / g]

(2) Pore volume Automatic N ₂ manufactured by CARLO-ERBA
Adsorption device (Sorptomatic Series 1
After 2hr degassed at 10 ^-2 mmHg, 250 ° C. with 800), temperature of liquid nitrogen, N ₂ in N ₂ pressure 735mmHg
The N ₂ adsorption amount (V1) in the standard state was calculated from the adsorption amount, and the pore volume was calculated from the following formula. Pore volume (PV) = V1 × 1.555 × 10 ⁻³ (ml /
g)

(3) Average Pore Radius (r) The average pore radius [(r), Å] was calculated from the following formula assuming that the pores are cylindrical. Average pore radius (r) = 2 x pore volume (PV) x 10 ⁴ / BET specific surface area (SA)

(4) Average particle size Coulter Count method
er, Model TA-2 type), the particle size obtained from the 50% volume distribution point of the cumulative particle size curve was taken as the average particle size.

(5) Ozone generator and ozone meter Experimental ozone generator manufactured by Nippon Ozone Co., Ltd. (ON-3-2
Type) to generate ozone, and the concentration of ozone was measured using an ozone densitometer OMD-50 type (measuring range 0 to 50 g / Nm ³ ) manufactured by Nippon Ozone Co., Ltd.

(6) Pseudo-boehmite-type hydrated alumina The pseudo-boehmite-type hydrated alumina used in the present invention was prepared by the method described below. Calcium carbonate concentration of 70 to 30 under stirring conditions of 70 ° to 120 ° C.
In a 0 g / l slurry (hereinafter referred to as charcoal slurry),
A slightly acidic (pH 2 to 3) aluminum nitrate solution having a concentration of 50 to 100 g / l as Al ₂ O ₃ was added at a rate of 100 to 1000 ml / min, and the pH of the reaction slurry after the addition was 6 to 8; The hydrated alumina was obtained by aging treatment for about 1 hour while slowly stirring at a temperature of 90 ° C. or lower. Next, it is filtered and washed with water at 110 ° C to 1
The hydrated alumina fine powder used in the present invention was dried at 50 ° C. and its properties are shown in Table 1.

[0036]

[Table 1]

(7) Porous Carbon The porous carbon used in the present invention has a calorific value of 300 emitted from a boiler combustion furnace using heavy oil or crude oil as a fuel.
Combustion soot containing 0 kcal / kg or more of unburned carbon as a main component is preferably used. The porous carbon used in the present invention has various physical properties with the oxide-based transition metal component shown in Table 2 in addition to the unburned carbon as the main component.

[0038]

[Table 2]

(8) Forming Aid In the present invention, natural or synthetic smectite clay minerals and zeolite having binder properties are replaced with a part of hydrated alumina in order to improve particle strength and adsorption properties. Can be used.

[0040]

[Table 3]

Example 1 Pseudo-boehmite hydrated aluminum, porous carbon, and a molding aid were dry-mixed in the amounts shown in Table 8, and the moisture content was adjusted to 50 to 60% by weight with a kneader. %
Kneading was carried out uniformly so that Next, this kneaded product was put into an extrusion granulator (EXD-60 type manufactured by Fuji Paudal) to granulate a columnar product having a particle size of 0.5 to 1.5 mm, and then the obtained granulated product was processed to 50 to 1 under rolling condition of 200ppm
After being treated for 1 to 3 minutes, the adsorbent according to the present invention having a water content of 0 to 5% by weight was prepared by primary drying at 100 to 150 ° C and then secondary drying at 200 to 400 ° C.
Then, the obtained adsorbent was irradiated with microwaves for 30 to 150 seconds using a household microwave oven to obtain a catalyst of the present invention.

[0042]

[Table 4]

Example 2 Sample No. After granulating the catalyst powder of No. 5 into a column shape of 1.5 mmφ × 5 mm, packed in a packed column having a length of 9 cm and a volume of 25 ml, and using an ozone generator, the ozone concentration at the inlet was 16.
After ozone was aerated for 10 hours under the condition of LHSV = 1200 hr ^{−1 at} 1 ppm, the ozone concentration at the column outlet was measured by an ozone densitometer OMD-50 and found to be 0% (Experiment 1).

Next, a new sample No. 5 with the same column at an inlet ozone concentration of 5000 ppm and LHSV =
After bubbling at 2400 hr ⁻¹ for 5 hours, the ozone concentration at the column outlet was measured and found to be 0% (Experiment 2).

Further, in the same column, the sample No. 3 and sample N
o. Using 5 catalyst 3 mmφ × 5 mm granules in half, ozone concentration 19.1 ppm, LHSV = 1200 h
When ozone was aerated at r ⁻¹ and the outlet ozone concentration was measured 5 hours after the aeration, it was at least 0.06 ppm as an environmental standard (Experiment 3).

Example 3 An ozone generator (ON-3-2 type) was used for the aeration layer containing the rotten smelling shellfish juice, and the ozone concentration was 16.1 pp.
After deodorizing with an air flow rate of 30 l / hr at m, the ozone concentration at the outlet of the aeration layer became 16 ppm or more, and then was passed through a column under the same conditions as in Experiment 1 of Example 2 so that ozone was decomposed. No ozone odor was felt even after 10 hours.

[0047]

According to the present invention, the specific surface area is 5 to 20.
By combining the porous carbon particles having a small m ² / g and containing a transition metal with pseudo-boehmite-type hydrated alumina and smectite to form a composition, a catalyst excellent in ozone decomposition performance and durability can be obtained. I was able to get it. In addition, a granular catalyst can be easily obtained, and this catalyst has an advantage that it has excellent powdering resistance and durability.

Further, since this carbon can be easily obtained as heavy oil soot or crude oil soot, there is an advantage that the catalyst cost is extremely low and the operating cost can be reduced as a whole.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph showing the particle structure of porous carbon used in the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B01J 27/02 ZAB M (72) Inventor Kiyohiko Imai 4-1-2-1, Nihombashi Muromachi, Chuo-ku, Tokyo Mizusawa Chemical Co., Ltd.

Claims (8)

[Claims] 1. A porous carbon particle containing a transition metal component and having a BET specific surface area in the range of 5 to 50 m ² / g and pseudo-boehmite hydrated alumina in a ratio of 1: 1.4 to 2: 1. In a weight ratio of 10 to 3 in total
An ozone decomposition catalyst comprising a composition containing 0% by weight of a synthetic or natural smectite group clay mineral or a synthetic or natural zeolite. 2. The ozone decomposition catalyst according to claim 1, wherein the transition metal component is at least one metal component selected from the group consisting of iron, nickel, cobalt, and vanadium. 3. The transition metal component is contained in the porous carbon particles in an amount of 1 to 20% by weight.
The ozone decomposition catalyst described. 4. The porous carbon particles contain an alkali metal component and / or an alkaline earth metal component in an amount of 0.
The ozone decomposition catalyst according to claim 1, wherein the ozone decomposition catalyst is contained in an amount of 1 to 2.0% by weight. 5. The porous carbon particles are 0.05 to 50.
The ozone decomposing catalyst according to claim 1, which has a median diameter of μm. 6. The porous carbon particles are 0.01 to 0.
The ozone decomposition catalyst according to claim 1, which has a pore volume of 05 ml / g. 7. The ozone decomposition catalyst according to claim 1, wherein the porous carbon particles are crude oil soot or heavy oil soot. 8. The catalyst as a whole is 100 to 250.
BET specific surface area of m ² / g and 0.1 to 0.35 ml /
The ozone decomposition catalyst according to claim 1, having a pore volume of g.