JPH047040A - Catalyst for decomposing ozone and production thereof - Google Patents

Abstract

PURPOSE:To prevent deterioration of catalytic performance and to enhance durability by forming a catalyst for decomposing ozone which is made of activated manganese dioxide, fluororesin and amorphous alumina and constituted of high-density granular bodies having specified sp. gr. and specified surface area. CONSTITUTION:A mixture is prepared by kneading activated manganese dioxide, a polyfluoroethylene-based binder and amorphous alumina hydrate. Then a catalyst for decomposing ozone is produced by molding this mixture into granules and thereafter calcining or drying the granules at <=400 deg.C. The obtained catalyst for decomposing ozone is made of activated manganese dioxide, fluororesin and amorphous alumina and constituted of high-density granular bodies having >=1.5g/cc bulk sp. gr. and >=30m<2>/g specific surface area. Deterioration in strength of the catalyst and in catalytic performance can be prevented because strength of the catalyst and hydrophobic property thereof are enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ozone decomposition catalyst for purifying ozone exhaust gas.

[Prior Art] Ozone has a strong oxidizing effect, so it is widely used for purification and sterilization of tap water, treatment of sewage or industrial waste liquid, denitration treatment and deodorization treatment of exhaust gas, etc. Excess ozone is used to ensure sufficient reaction, so excess unreacted ozone is discharged.

Ozone is also emitted from equipment that involves electrophotographic corona discharge.

Ozone is a gas with a very strong odor and is present in the air at 0.
If more than 1 ppm of ozone is present, it will have an adverse effect on the human body, so it is necessary to decompose and remove this excess ozone.

Therefore, rendering ozone harmless has become important in terms of environmental health.

Conventionally, methods for decomposing ozone include adsorption of ozone with activated carbon, or activation of activated carbon, inorganic carriers such as alumina, phosphoric acid, titania, etc., honeycomb carriers such as cordierite and paper, and manganese, nickel, cobalt, chromium, copper, etc.
A method of decomposing ozone by bringing a catalyst attached with catalyst components such as silver, platinum, palladium, rhodium, etc. into contact with ozone is disclosed in Japanese Patent Publication No. 56-17939 and Japanese Patent Application Laid-open No. 62-201.
It is described in Publication No. 648, etc.

Furthermore, JP-A No. 51-4094 discloses that a gas containing ozone is brought into contact with activated manganese oxide, and JP-A-60-7940 discloses a mixed solution of soluble manganese salts and soluble copper salts. It is described that after adding an oxidizing agent thereto, neutralization is performed with an alkaline solution containing permanganate, the resulting precipitate is dried, and formed into a pellet or the like together with alumina sol or sodium silicate.

[Invention or problem to be solved] Ozone decomposition catalysts such as those described above are used in boat fishing at normal temperatures below 25°C, and granular activated carbon, activated carbon honeycomb, etc. have good initial performance or are durable in a short period of time. Performance will deteriorate.

In addition, waste ozone obtained after ozone is used for purification and sterilization of tap water, treatment of sewage or industrial waste liquid, etc. contains a large amount of water, so that the catalyst strength and performance are reduced due to moisture.

An object of the present invention is to provide a catalyst for ozone decomposition that exhibits less deterioration in catalyst strength and catalyst performance due to moisture and has durability.

[Means for Solving the Problems] The present invention has been accomplished in order to solve the above problems. That is, the ozone decomposition catalyst of the present invention is composed of active manganese dioxide, a fluororesin, and amorphous alumina, and has a bulk specific gravity of 1-5 g/cc or more and a specific surface area of 30 m2/cc.
It is characterized by being a high-density granular material with a particle size of more than g.

Bulk specific gravity is less than 1.5g/cc and specific surface area is 30m2
If the amount is less than /g, the strength of the catalyst carrier and the performance of the catalyst will decrease, which is not preferable.

In addition, the method for producing the ozone decomposition catalyst described above includes kneading a mixture of activated manganese dioxide, a polyfluoroethylene binder, and amorphous alumina hydrate, forming the mixture into granules, and then calcining or drying the mixture at 400°C or lower. It is characterized by Furthermore, it is also possible to add pure water to the activated manganese dioxide, the polyfluoroethylene binder, and the amorphous alumina hydrate, if necessary.

In the method of the present invention, when an alumina hydrate having a hemite structure or a pseudo-hemite structure is used instead of an amorphous alumina hydrate, the bonding property with active manganese dioxide is insufficient, resulting in a decrease in catalyst strength. .

Additionally, if the polyfluoroethylene binder is calcined or dried above 400°C, it evaporates as hydrogen fluoride and is no longer present in the catalyst, resulting in a decrease in catalyst performance due to moisture absorption by the catalyst, and a decrease in catalyst strength. .

[Function] The present invention uses a polyfluoroethylene binder and amorphous alumina hydrate as binders, so it is easy to mold, and the use of amorphous alumina hydrate has good bonding properties with activated manganese dioxide. Moreover, since the catalyst is calcined or dried at a temperature below 400°C, the fluororesin is present in the catalyst, giving it strength and hydrophobicity.
Prevents deterioration of catalyst strength and catalyst performance.

[Example] Examples of the present invention will be described below.

Example 1 99 parts by weight of activated manganese dioxide powder, 5 parts by weight of polyfluoroethylene binder (product name: Fluon, manufactured by Asahi Glass Co., Ltd.), and amorphous alumina hydrate (product name: A)
25 parts by weight of S-200 (manufactured by Nissan Kigenso Co., Ltd.) were kneaded, extruded using a disk Beretta to have a diameter of 3III + 1 and a length of 5, and dried at 300°C to obtain a granular catalyst A for ozone decomposition.

This granular catalyst had a bulk specific gravity of 1.62 g/cc and a specific surface area of 48 m2/g.

Example 2 99 parts by weight of activated manganese dioxide powder, 5 parts by weight of polyfluoroethylene binder (Fluon) and 25 parts by weight of amorphous alumina hydrate (AS-200) were kneaded, and the mixture was mixed with a disc beretter to a diameter of 311111 and a length of 5. After molding with a diameter of 1 mm, the catalyst was dried at 400° C. to obtain a granular catalyst B for ozone decomposition.

This granular catalyst had a bulk specific gravity of 1.65 g/cc and a specific surface area of 51 m27 g.

Example 3 99 parts by weight of activated manganese dioxide powder, 5 parts by weight of polyfluoroethylene binder (Fluon), and 25 parts by weight of amorphous alumina hydrate (AS-200) were kneaded, and the mixture was mixed with a disc pelleter using a disk pelleter to form a mixture of 3 diameters and 3 lengths. After extrusion molding in 5 steps,
It was dried at 100° C. to obtain ozone decomposition granular catalyst C.

This granular catalyst had a bulk specific gravity of 1.53 g/cc and a specific surface area of 43 m2/g.

Comparative Example 1 Coal-based carbonized coal is activated and has a bulk specific gravity of 0.55 g/c
c. Granular activated carbon with a specific surface area of 1000 m2/H was obtained.

Comparative Example 2 99 parts by weight of activated carbon powder and 40 parts by weight of amorphous alumina hydrate (AS-200) as a binder were kneaded and extruded using a disk pelleter to obtain granular activated carbon E.

This granular catalyst had a bulk specific gravity of 0.51 g/cc and a specific surface area of 880 m2/g.

Comparative Example 3 The activated carbon obtained in Comparative Example 2 was immersed in a manganese nitrate solution and dried at 50°C to obtain manganese-impregnated carbon F. The amount of manganese supported was 50 g/D.

This granular catalyst had a bulk specific gravity of 0.52 g/cc and a specific surface area of 885 m2/g.

Comparative Example 4 100 parts by weight of activated manganese dioxide powder and a hemite-based binder [(trade name: Disp-al) Condeia (trade name: Disp-al)]
CONDEA) 10 parts by weight and 10 parts by weight of pure water were kneaded using a disc pellet soter to a diameter of 3 mm and a length of 5.
After pressing and molding, it was dried at 300°C to obtain a granular catalyst G for ozone decomposition.

The bulk specific gravity of this granular catalyst is 1.3 g/cc, and the specific surface area is 4.
It was 5m2/g.

Comparative Example 5 An attempt was made to knead 99 parts by weight of activated manganese dioxide powder and 50 parts by weight of a polyfluoroethylene binder (Fluon) and extrude the mixture into a diameter of 3III mm and a length of 5 mm using a disc beretter. There wasn't.

Comparative Example 6 99 parts by weight of activated manganese dioxide powder, 5 parts by weight of polyfluoroethylene binder (Fluon) and 25 parts by weight of amorphous alumina hydrate (AS-200) were kneaded and mixed with a disk pelleter to a diameter of 3 inches long. After extrusion molding to 5 mm, it was dried at 500°C to obtain a granular catalyst H for ozone decomposition.

This granular catalyst had a bulk specific gravity of 1.68 g/cc and a specific surface area of 43 m2/g.

The durability and evaluation of catalysts A-H thus obtained were carried out under the following conditions, and the results are shown in Table 1. Further, Table 2 shows the catalyst strength determined as 7111 by the Mizuya hardness measuring method.

<Durability and evaluation conditions> Ozone (03) 2000ppm Air Balance SV (space velocity) 10,000HrRH (relative humidity) 100% Temperature 25°C Floor table 2 As is clear from Table 1, the catalyst of the present invention It has superior durability compared to activated carbon and catalysts.

In other words, the initial performance of the catalyst using only activated carbon as seen in Comparative Example 1 is as good as that of the present invention, but it rapidly decreases after 50 hours, and after 100 hours, the ozone purification rate is almost the same. It's gone. Catalyst E of Comparative Example 2, which does not contain manganese dioxide and fluororesin, is the catalyst of Comparative Example 1.
Similarly, the initial performance is as good as that of the present invention, but it rapidly decreases after 50 hours, and the ozone purification rate has almost disappeared after 100 hours.

Catalyst F of Comparative Example 3, which supports manganese but does not contain fluororesin or amorphous alumina, has a slightly higher ozone purification rate than Comparative Example 1.2, but after 200 hours, the ozone purification rate is The rate has almost disappeared,
This is unfavorable in terms of catalyst durability. Furthermore, although Catalyst G of Comparative Example 4 uses a boehmite-based binder, it can be seen that the ozone purification rate after 50 hours has decreased compared to the catalyst of the present invention. In addition, whether the catalyst H of Comparative Example 6 had a drying temperature of 500°C, or whether it had the same level of catalyst strength as the catalyst of the present invention, or whether it was dried after a period of time, especially after 100 hours. The ozone purification rate is lower than that of the catalyst of the present invention.

Furthermore, as is clear from Table 2, the catalyst of the present invention is superior in catalytic strength (hardness) compared to conventional activated carbon and catalysts.

[Effects of the Invention] As is clear from the above, the ozone decomposition catalyst of the present invention comprising activated manganese dioxide, fluororesin, and amorphous alumina is superior in durability and catalytic strength compared to conventional activated carbon and catalysts.

Applicant's agent: Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) For ozone decomposition, the material is made of activated manganese dioxide, fluororesin, and amorphous alumina, and is a high-density granular material with a bulk specific gravity of 1.5 g/cc or more and a specific surface area of 30 m^2/g or more. catalyst. (2) An ozone decomposition catalyst characterized by forming a mixture of activated manganese dioxide, a polyfluoroethylene binder, and amorphous alumina hydrate into granules, and then calcining or drying the mixture at 400°C or lower. manufacturing method.