JP3429331B2 - Ozone decomposition catalyst - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a pore volume of 0.2 to
Heavy γ by a chemical synthesis method having a specific surface area of 0.5 cc / g, a specific surface area of 80 m ² / g or more, and a specific volume of 0.7 to 2.0 cc / g.
The present invention relates to an ozone decomposing catalyst having a long catalyst life, which has an excellent ozone decomposing activity composed of —MnO ₂ and further exhibits a high ozone decomposing activity even under a condition of high relative humidity and which has excellent stability and a long catalyst life.

[0002]

2. Description of the Related Art Manganese dioxide includes natural manganese dioxide, manganese dioxide produced by an electrolytic method, manganese dioxide produced by a chemical synthesis method, and the like.
There are various forms such as manganese dioxide, β-manganese dioxide, γ-manganese dioxide, ε-manganese dioxide, δ-manganese dioxide, and amorphous manganese dioxide.

As is well known, manganese dioxide is widely used as a depolarizer for dry batteries, and it exhibits manganese dioxide having excellent discharge characteristics and a sufficiently high density so that it can be compressed and filled into dry batteries. In order to manufacture
For example, as shown below, various methods have been proposed.

In Japanese Patent Laid-Open No. 59-184733, manganese dioxide containing 70% by weight or more of manganese dioxide obtained by oxidizing manganese carbonate in a sulfuric acid solution is used.
A method for producing manganese dioxide, which is treated at a temperature of 100 to 100 ° C, is disclosed.

In Japanese Patent Publication No. 60-52093, production of heavy manganese carbonate is characterized in that a reaction is carried out at a temperature of 40 to 90 ° C. while simultaneously adding a manganese sulfate aqueous solution and an alkali carbonate aqueous solution in proportion. The method and its use as a raw material for the chemical synthesis of manganese dioxide for dry batteries are described.

JP-A-60-221324 discloses that manganese dioxide obtained by roasting manganese ore or manganese salt at a temperature of 400.degree.
A method for producing manganese dioxide is characterized in that the manganese dioxide powder is compression-molded by a roll press under a pressure of 1 to 10 ton / cm ² , and then the manganese dioxide after the molding is pulverized to a desired particle size. Is taught.

Japanese Unexamined Patent Publication (Kokai) No. 61-14137 is characterized in that a manganese compound is firstly treated with nitric acid or an acid other than nitric acid having a concentration of 2N or less, and then secondarily treated with a relatively concentrated acid. A method for producing manganese dioxide is described.

The production methods described in these publications are all related to the production method of manganese dioxide which is suitable as a material for dry batteries, and other uses are not described or even suggested.

On the other hand, many attempts to use manganese dioxide as a catalyst for ozone decomposition have already been proposed.

For example, in Japanese Patent Laid-Open No. 53-14688, a refractory inorganic oxide carrier is used as Ti, V, Cr, Mn, F.
e, Co, Ni, Cu, Zr, Nb, Mo, Ru, R
A method for producing an ozone decomposition catalyst in which a solution containing at least one transition metal salt selected from h, Pd, Ag, Sn, W, and Pb is impregnated and supported is disclosed.

JP-A-51-4094 discloses a method for producing active manganese oxide by blowing oxygen or air into an aqueous solution of manganese sulfate in the presence of an equivalent amount of ammonia to oxidize it, and a gas containing ozone. A method for decomposing and removing ozone in an ozone-containing gas by contacting with this active manganese oxide is disclosed.

Japanese Unexamined Patent Publication (Kokai) No. 51-71299 proposes a method for producing active manganese dioxide by adding potassium permanganate to an acidic aqueous solution of a manganese salt, reacting the mixture, and aging.

Japanese Unexamined Patent Publication (Kokai) No. 58-183928 discloses a method for removing ozone from an ozone-containing gas, which comprises contacting a gas containing ozone with γ-MnO ₂ to reduce the oxygen. There is. The same publication describes γ-M
nO ₂ is a γ-type polycrystal having no orientation depending on the manufacturing method.
MnO ₂ (electrowinning), the number of facets having an X-ray diffraction intensity of 2θ = 28 °, γ-MnO ₂ (electrowinning) in a fiber structure having directivity in γ (110) plane and γ (021) plane, and chemical synthesis Γ-MnO ₂ according to the chemical method is roughly classified into three types, and the specific surface area of γ-MnO ₂ by the chemical synthesis method is slightly smaller than that of the other two electrolytically-collected γ-MnO ₂ , and the catalytic activity and It teaches that the longevity characteristics of sustaining activity show poor performance. Further, in the same publication, γ-by chemical synthesis method
MnO ₂ has a small specific surface area, and when it is used, ozone purifying ability is rather poor, and γ-obtained by electrowinning
Even with MnO ₂ , it can be seen that the catalyst life is deteriorated when the specific surface area becomes a high specific surface area of 120 m ² / g or more. Therefore, the specific surface area of γ-MnO ₂ should take into consideration the initial purification capacity and the life characteristics. Teach that a range of 12 to 120 m ² / g is preferred.

[0014]

As described above, conventionally, when manganese dioxide is used as a catalyst for ozone decomposition, γ-MnO ₂ having a specific surface area obtained by electrowinning or a relatively small ratio is used. It has only been shown that manganese dioxide having a surface area alone or a mixture with other substances can be used, and it is difficult to say that it has a sufficient ozonolytic activity as a catalyst for ozonolysis, and a high relative It also did not have sufficient ozonolytic activity in a humid environment.

[0015]

Means for Solving the Problems As a result of intensive studies to develop manganese dioxide having excellent activity as a catalyst for ozone decomposition, the present inventors have found that it has a small specific surface area and has been used as a catalyst for ozone decomposition. , Which is said to be inferior, synthesizes γ-MnO ₂ by a chemical synthesis method under specific conditions and then grinds it into a heavier state to increase its specific surface area and specific volume. It has been found that a heavy γ-MnO ₂ is obtained which can significantly improve the catalyst life capable of sustaining the activity and can maintain its high ozonolysis activity even under high relative humidity conditions. The present invention has been completed based on such findings.

That is, the present invention has a pore volume of 0.2 to
At 0.5 cc / g, 80% or more of pore distribution is 40 to 25
It has a pore diameter range of 0 Å, a specific surface area of 80 m ² / g or more, and a specific volume of 0.7 to 2.0 cc / g.
Another object of the present invention is to provide an ozone decomposition catalyst comprising heavy γ-MnO _{2 produced} by the chemical synthesis method. That is, even if the γ-MnO ₂ alone has sufficient ozone decomposing activity, it is possible to decompose and remove ozone by applying it to the wall of the reaction chamber or the like, but to further improve ozone decomposing performance. Can be achieved by increasing the apparent surface area by supporting it on a carrier, preferably a porous carrier. The supporting method may be a conventional method such as a wash coat using a binder, a spray method or a dipping method. Suitable carriers are activated carbon, porous inorganic carriers such as alumina, silica-alumina, titania silica, zeolite, sepiolite and the like, but non-porous substances such as cordierite and metals are not excluded. Also, an organic carrier such as paper or polyurethane can be used. The shape of the carrier is honeycomb, extruded integrally molded body, foam, pellets, fibers,
Any shape such as a sheet can be used according to the purpose. The amount of heavy γ-MnO ₂ supported on the carrier is 70 to 200 g, preferably 12 per 1 volume of the catalyst.
It is 0 to 180 g. Further, it is not limited to use in place of conventional manganese dioxide.

Heavy γ-MnO ₂ is Mn ₃ O ₄ or manganese oxide such as Mn ₂ O ₃ or Mn ₃ O ₄ obtained by oxidizing and roasting manganese ore or manganese salt at a temperature of 400 ° C. or higher. In addition to mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid, heat treatment is performed at a temperature of 70 ° C. or higher for 10 minutes to 10 hours, preferably 30 minutes to 1 hour to produce γ-MnO ₂ , which is further converted to γ-MnO _{2. 2}
Has a specific volume of 0.7 to 2.0 cc / g, preferably 0.8 to
It can be produced by crushing and heavy treatment until it reaches 1.2 cc / g.

[0018] Mn ₃ used in the present invention O ₄ is commercially available Mn ₃ be O ₄ as it is used to, Mn ₂ O obtained manganese ore or manganese salt oxidizing roasting at 400 ° C. or higher temperature ₃ , manganese oxide such as Mn ₃ O ₄ may be used. In this case, manganese ores include MnO ₂ (soft manganese ore), MnCO ₃ (rhodomanganese ore), Mn.
Any compound containing ₂ O ₃ , Mn ₃ O _4, etc. as a main component may be used, and preferable manganese salts include MnSO ₄ , MnCO ₃ , Mn.
(NO ₃ ) _{2 and the} like can be mentioned.

When using sulfuric acid, the mixing ratio of sulfuric acid and Mn ₃ O ₄ , that is, the molar ratio of H ₂ SO ₄ / Mn ₃ O ₄ is
It is 1.0 to 10.0, preferably 1.8 to 5.0.
Of course, even if it is out of this range, γ- which is the object of the present invention
MnO ₂ can be obtained.

The concentration of sulfuric acid used is not particularly limited, but a sulfuric acid solution of 2 to 6 N is preferable. That is, in a sulfuric acid solution of less than 2 N, if the H ₂ SO ₄ / Mn ₃ O ₄ molar ratio is 1.0, the target treatment cannot be achieved unless the amount of the treatment solution is increased, while the H ₂ SO ₄ When the molar ratio of / Mn ₃ O ₄ is 10.0, the amount of the solution becomes small at a concentration exceeding 6 N, and it becomes difficult to form a slurry, which makes the treatment difficult. The heat treatment temperature is 65 ° C. or higher, preferably 70 to
A good effect is obtained at 100 ° C. The heat treatment time is 10 minutes to 10 hours, preferably 20 minutes to 1 hour.
That is, if the heat treatment time is too short, the reaction temperature cannot be made uniform and uniform conversion to γ-MnO ₂ cannot be performed. On the other hand, γ-Mn obtained when the heat treatment time is too long
Both the pore volume and the specific surface area of O ₂ are reduced.
Pore volume is 0.2 to 0.5 cc / g, preferably 0.2
~ 0.4 cc / g. Specific surface area (by BET method)
Is 80 m ² / g or more, preferably 90 m ² / g or more.

The heat-treated γ-MnO ₂ is a kneader,
It can be made heavy by an ordinary processing means such as a press or a ball mill method. The heavier one has a specific volume of 0.7 to 2.0 cc / g, preferably 0.8 to 1.2 cc / g. If the heaviness is insufficient, a high-concentration slurry cannot be obtained, making it difficult to adjust the viscosity of the slurry. In addition, a slurry having little thixotropy, that is, a slurry which does not lose fluidity even when left to stand cannot be obtained. The specific volume (cc / g) means the sample manganese dioxide having a particle size adjusted to 200 mesh or less, put in a cylinder having an inner diameter of 28 mm and a volume of 100 cc, and dropping the volume (cc) after dropping 300 times from a height of 20 mm. The value is divided by the weight (g) of the sample, that is, the volume per unit weight is shown.

The present invention will be described in more detail below with reference to examples of the present invention, but the present invention is not limited to these examples.

[0023]

Example 1 248 g of 95% concentrated sulfuric acid was diluted with ion-exchanged water to prepare 960 cc of 5N sulfuric acid solution. The temperature of the obtained sulfuric acid solution was adjusted to 70 ° C., and 229
g of Sofmax (containing 99.3% of Mn ₃ O ₄ ) manufactured by Chuo Denki Kogyo Co., Ltd. was added with good stirring and the mixture was heated at a temperature of 70 ° C. for 1 hour. After completion of the heat treatment, the precipitate separated by filtration was repeatedly washed with ion-exchanged water until the filtrate had a pH of 3.0 or higher. The precipitate is taken out and the temperature is 150 ° C for 1
After drying for 0 hour, γ-MnO ₂ having a specific volume of 2.40 cc / g
Was obtained. FIG. 1 shows a surface photograph of the surface under a scanning electron microscope. As is clear from FIG. 1, the γ-MnO ₂ prepared in this way has needle-like protrusions, has a low bulk density, and a high-concentration slurry cannot be obtained. Therefore, when the carrier was wash-coated with this low-concentration slurry, the amount supported was small and sufficient activity could not be obtained.

50 g of the obtained dry γ-MnO ₂ (volume: 100 cc) was placed in a ball mill container (internal volume: 500 cc) and subjected to a ball mill treatment for 10 hours to make it heavy, and a specific volume of 0.84 cc / g of heavy γ was obtained. -MnO ₂ was obtained. FIG. 2 shows a surface photograph of the surface under a scanning electron microscope. Second
As is clear from the figure, it is confirmed that the needle-like protrusions on the surface of the heavy-weighted γ-MnO ₂ are removed.
500 g of the heavy γ-MnO ₂ thus prepared and 150 g of Snowtex O (containing 20% colloidal silica) manufactured by Nissan Chemical Industries, Ltd. were well mixed with 780 g of ion-exchanged water to prepare a slurry. Ceramic fiber honeycomb manufactured by Nichias Co., Ltd. with a capacity of 600 cells / square inch (product name "Hanicle", length 75 mm, width 7)
(5 mm, height 10 mm) was immersed in the slurry, and then the excess slurry was taken out and blown with air to remove it.
A catalyst A having a specific surface area of 138 m ² / g and a supported amount of heavy γ-MnO ₂ of 161 g / l was prepared by drying at a temperature of ° C for 5 hours.

[0025]

[Comparative Example 1] 500 g of γ-M having a specific volume of 2.40 cc / g which has not been subjected to a heavy treatment by the ball mill of Example 1
780 with nO ₂ and 150 g of Snowtex O (containing 20% of colloidal silica) manufactured by Nissan Chemical Industries, Ltd.
When mixed with g of ion-exchanged water, it became muddy and a washcoatable slurry could not be obtained.

[0026]

[Comparative Example 2] In Comparative Example 1, 1210 of ion-exchanged water was used.
When the amount was increased to g and mixed, a slurry capable of wash coating was prepared. The hanicle carrier used in Example 1 (75 mm long, 75 mm wide, 10 m high) was added to this slurry.
m) is soaked, the excess slurry is taken out and blown with air to remove, and dried at a temperature of 150 ° C. for 5 hours to obtain γ-MnO ₂
A catalyst X having a supported amount of 59 g / l was prepared.

[0027]

[Comparative Example 3] In Example 1, the heavy γ-MnO ₂ produced by the method of the present invention was converted into electrolytic γ-MnO ₂ manufactured by Toso Corporation.
(Brand name "Denman FM", 95.5% of γ-MnO ₂
Except that the specific surface area is 54 m.
^A catalyst Y having a supported amount of ² / g of γ-MnO ₂ of 157 g / l was prepared.

[0028]

Comparative Example 4 In Example 1, the heavy γ-MnO ₂ produced by the method of the present invention was chemically synthesized γ-MnO ₂ manufactured by Chuo Denki Kogyo Co., Ltd. (trade name “SELMAX”, γ-MnO ₂ 91%). %), And a catalyst Z having a specific surface area of 47 m ² / g and a supported amount of γ-MnO ₂ of 138 g / l was prepared in the same manner.

[0029]

[Test Example 1] Ozone concentration is 2 ppm, relative humidity is 40
%, The sample gas whose temperature was adjusted to 20 ° C. was charged to a reactor loaded with a sample catalyst (diameter 22 mm, thickness 10 mm) 180
Flowing at a space velocity of 000 hr ⁻¹ and measuring the ozone concentration at the inlet and outlet of the reactor after 2 hours and 10 hours,
The percentage of the difference between the inlet concentration and the outlet concentration divided by the inlet concentration, that is, the ozone decomposition rate was obtained.

The ozone decomposition rate was determined by using the catalyst A of the present invention prepared in the above-mentioned Example 1 and Comparative Example 2 and the catalyst X composed of γ-MnO ₂ which is not made heavy, and the results are shown in Table 1.

[0031]

Table 1 Supported amount of catalyst Ozone decomposition rate (%) (g / l) After 2 hours and after 10 hours Catalyst A 161 94 90 Catalyst X 59 89 71 As apparent from Table 1, it was made heavy by the method of the present invention. It is proved that the catalyst using γ-MnO ₂ obtained as described above can support a large amount of γ-MnO ₂ , and exhibits excellent ozonolysis activity.

The above Example 1 and Comparative Examples 3 and 4
The catalyst A of the present invention prepared in 1. and commercial electrolytic γ-MnO
_{Using the} catalyst Y composed of ₂ and the catalyst Z composed of commercially available chemically synthesized γ-MnO ₂ , the ozone decomposition rate was similarly obtained, and the results are shown in Table 2.

[0033]

[Table 2] Type of catalyst MnO ₂ Specific surface area Supported amount Ozone decomposition rate (%) (m ² / g) (g / l) After 2 hours and after 10 hours Catalyst A Chemical synthesis γ-MnO ₂ 138 161 94 90 Catalyst Y electrolysis γ-MnO ₂ 54 157 86 53 53 catalyst Z chemical synthesis γ-MnO ₂ 47 138 84 41 As is clear from Table 2, the catalyst using γ-MnO ₂ obtained by heaviening by the method of the present invention is The activity as an ozone decomposition catalyst is superior to that of a catalyst composed of γ-MnO ₂ prepared by the conventional electrolysis method and chemical synthesis method, and high activity can be maintained for a long time, that is, with high activity. This proves that the stability is excellent and the catalyst life is long.

[0034]

Example 2 Catalysts B, C, D and E were prepared in the same manner as in Example 1 except that the heat treatment time in Example 1 was changed from 1 hour to 10 hours, 3 hours, 2 hours and 30 minutes. Prepared.

[0035]

Test Example 2 In the same manner as in Test Example 1 above, using the catalysts A to E prepared according to Examples 1 and 2, 2 hours and 1
The ozone concentration at the inlet and the outlet of the reactor after the lapse of 0 hours was measured, and the ozone decomposition rate was determined and shown in Table 3.

[0036]

[Table 3] Catalyst Pore volume Specific surface area Supported amount Ozone decomposition rate (%) (cc / g) (m ² / g) (g / l) 2 hours later 10 hours catalyst B 0.217 69 141 91 65 Catalyst C 0.214 91 155 93 93 85 Catalyst D 0.213 105 145 945 94 Catalyst A 0.315 138 161 194 90 Catalyst E 0.362 159 159 96 91 91 As can be seen from Table 3, depending on the heat treatment time, γ- M
nO ₂ has different pore volumes and specific surface areas, and the ozone decomposition rate after 10 hours improved as the pore volume and specific surface area increased. In addition, chemically synthesized γ-MnO ₂ (0.315 cc / g, 138 m ² / with large pore volume and specific surface area)
g; 0.362 cc / g, 159 m ² / g) proved that the ozone decomposition rate was small and the stability was good.

[0037]

[Test Example 3] In the above Test Example 1, the relative humidity was set to 12
%, 40% and 70%, and the catalyst A and the catalyst Y and the catalyst Z obtained in Example 1 and Comparative Examples 3 and 4 above.
The ozone decomposition rate under each relative humidity condition was calculated, and the results are shown in Table 4.

[0038]

[Table 4] Decomposition rate of catalyst ozone (%) Relative humidity 12% Relative humidity 40% Relative humidity 70% 2 hours after 10 hours 2 hours after 10 hours 2 hours after 10 hours Catalyst A 96 90 94 89 80 41 Catalyst Y 92 66 66 91 66 60 25 Catalyst Z 86 42 85 40 75 75 28 As is clear from Table 4, the catalyst using the heavy γ-MnO ₂ prepared by the method of the present invention is a conventional electrolytic γ- Mn
Compared with the one using O ₂ and γ-MnO ₂ prepared by the conventional chemical synthesis method, it shows an excellent ozone decomposition rate even in a high relative humidity environment, and the ozone decomposition rate also shows little change with time. It was proved that the stability was remarkably improved and it had excellent moisture resistance.

Further, the same test was carried out for the catalyst B, the catalyst D and the catalyst E prepared in Example 2 to obtain the ozone decomposition rate under each relative humidity condition, and the results are shown in Table 5.
Shown in.

[0040]

[Table 5] Decomposition rate of catalyst ozone (%) Relative humidity 12% Relative humidity 40% Relative humidity 70% 2 hours later 10 hours later 2 hours 10 hours later 2 hours 10 hours later Catalyst B 92 66 91 65 63 22 22 catalyst D 95 90 94 87 80 40 40 catalyst E 96 92 96 91 91 83 43 As is clear from Table 5, when the heat treatment time is increased,
This proves that the ozone decomposition rate decreases in a high relative humidity environment.

The adsorption isotherm of the pore distribution was measured using a Sorptomatic 1800 manufactured by Carlo Erba Co., and the pore volume v (cc) and the pore diameter were measured by a numerical calculation method by the CI method (Cranston-Inkley method). The pore distribution function v / d (cc / Angstrom) consisting of d (Angstrom) and the catalyst E of the present invention prepared in Example 2 and Comparative Examples 3 and 4 and commercially available electrolytic γ- A catalyst Y made of MnO ₂ and a commercially available chemically synthesized γ-MnO ₂ catalyst Z are shown in FIG. 3, and catalysts B, D and E prepared in Example 2 are shown in FIG. 4.

"Porous Material" edited by Renichi Kondo (Gihodo Showa 5)
According to the capillary condensation theory shown on pages 47 to 48 of August 0), the relationship between relative humidity (%) and Kelvin radius r (angstrom) at which water in the air is condensed is shown in Table 6. Have a relationship like

[0043]

[Table 6] Relative Humidity and Pore Radius (20 ° C) Relative Humidity (%) r Relative Humidity (%) r 100 ∞ 70 70 31 98 550 60 22 22 95 217 50 16 90 90 105 40 40 12 80 50 30 30 9 Thus, for example, when the relative humidity is 60%, the water content in the air is condensed in the pores having the pore diameter of 44 angstroms or less, the catalyst surface is reduced, and the activity is lowered. Actually, not only the pores having a diameter of 44 angstroms or less, but also the catalyst surface adsorbs condensed water, and the pores having a larger pore diameter are covered with water, and the effective surface area of the catalyst Is reduced and the ozone decomposing activity is reduced. Therefore, in an environment with a high relative humidity, in order to maintain a high ozone decomposing activity, it is difficult for water in the air to condense to close the pores, that is, γ-MnO ₂ having a large number of pores having a larger pore size. Need to be prepared.

As is apparent from FIG. 3, the catalyst using the heavy γ-MnO ₂ prepared by the method of the present invention has a pore volume of 0.362 cc / g and a pore diameter of 40 Å or more. whereas pores the majority having a conventional electrolytic gamma-MnO ₂ and catalyst using gamma-MnO ₂ prepared in conventional chemical synthesis method, a pore volume of 0.095cc / g, and As small as 0.085 cc / g,
The majority of the pores have a pore diameter of 80 Å or less. This supports the result of Test Example 3 in which the water content in the air was condensed in a high humidity environment to close the pores and the activity of the conventional catalyst having a small pore diameter was lowered.

Further, as is clear from FIG. 4, when the heat treatment time is lengthened, the pore volume decreases, and the pore distribution of γ-MnO ₂ tends to be biased toward the smaller pore diameter. This similarly supports the result of Test Example 3 in which the ozone decomposition rate of the catalyst B having a long heat treatment time was reduced in a high humidity environment.

[0046]

The specific surface area is large and 40 angstroms
The ozone decomposition catalyst using the heavy γ-MnO ₂ having a specific volume of 0.7 to 2.0 cc / g occupies most of the pores having a pore diameter of not less than 10 μm. Compared with the catalyst using γ-MnO ₂ prepared by the synthetic method, it has an excellent activity as an ozone decomposition catalyst and is excellent in stability capable of sustaining high activity for a long time, and at the same time, even in a high humidity environment. It has excellent activity and stability.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph of γ-MnO ₂ of Example 1 before a heavy treatment.

FIG. 2 is a surface photograph of γ-MnO _{2 obtained} in Example 1 after a heavy treatment by a scanning electron microscope.

FIG. 3 is a graph showing the pore distribution of γ-MnO ₂ prepared in Example 1, Comparative Example 3 and Comparative Example 4.

FIG. 4 is a graph showing the pore distribution of γ-MnO ₂ prepared in Example 2.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiko Natsukari 1212 Shinomiya, Hiratsuka City, Kanagawa Prefecture JGC Universal Co., Ltd. (72) Inventor Ryoji Aikawa 1212 Shinomiya, Hiratsuka City, Kanagawa Prefecture JGC Yuniversal Co., Ltd. (56) References JP-A-5-23590 (JP, A) JP-A 1-245850 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00 -38/74 B01D 53 / 86

Claims (2)

(57) [Claims] 1. A pore volume of 0.2 to 0.5 cc / g, a specific surface area of 80 m ² / g or more, and a specific volume of 0.7 to 2.0 cc.
The ozone decomposition catalyst is characterized in that it is composed of heavy γ-MnO ₂ obtained by a chemical synthesis method. 2. The ozone decomposition catalyst according to claim 1, wherein 80% or more of the pore distribution is in the range of the pore diameter of 40 to 250 angstrom.