JP3126012B2 - How to Prevent Odor Generation from Ozone Filter - 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 preventing an odor from being generated from an ozone filter using an active manganese dioxide catalyst. Note that, in this specification,
Generated from office equipment such as portable copiers and laser printers
Although it contains ozone at a low concentration, it makes you feel a particularly bad smell
For decomposing ozone by treating indoor air that is not
"Ozone filter" in a sense limited to filters
U.

[0002]

2. Description of the Related Art Ozone has two effects on humankind. In other words, ozone is widely used in the fields of medicine, food, etc. for its bactericidal action based on its strong oxidizing ability. On the other hand, based on the toxicity of ozone itself, when the concentration in air exceeds 0.1 ppm, respiration occurs. Make the system feel stimulus 5
Above 0 ppm it is dangerous to life. Accordingly, in recent years, with the spread of office equipment that generates ozone, such as electrostatic copying machines and laser printers, and the causes of ozone generation have increased, it has been desired to develop a simple method for decomposing ozone in air. .

Conventionally, techniques for detoxifying low-concentration ozone in the air include an activated carbon adsorption method, a thermal decomposition method, a wet method, and a catalytic cracking method. However, catalytic cracking is highly safe and is carried out at room temperature. It is advantageous in many respects, such as being possible and easy to implement on a small scale. An example of an ozone filter which enables simple and small-scale catalytic decomposition of ozone is described in JP-A-5-23591.
Here, an ozone filter in which an active manganese dioxide catalyst is supported on a carrier having a honeycomb structure made of high porosity paper has been proposed.

[0004] An ozone filter using an active manganese dioxide catalyst has the feature of exhibiting excellent ozone resolution over a long period of time. However, in rare cases, when used for a long period of time, an odor may be generated even if there is no abnormality in the ozone resolution, and this is pointed out as a problem.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have examined the above-mentioned ozone filter which emits a bad smell as a result of long-term use, and as a result, have confirmed that a large number of organic compounds are adsorbed on the filter. . The main organic compounds identified are acetone, 2-propanol, tert-butanol, methyl ethyl ketone, lower fatty acids, chloroform, toluene, butyl acetate, ethyl benzene, xylene, butyl ethyl ketone, styrene, α-methyl styrene, o -Xylene, acetophenone, tert-butylphenyl ether, dimethylbiphenyl and the like. These compounds are not adsorbed on the ozone filter before use, or they are adsorbed to a very small extent. It is estimated to be.

[0006] The reason that these compounds, which are hardly present in the atmosphere of the normal environment, were adsorbed on the filter, was as follows.
It is considered as follows. The air contains a trace amount of organic components emitted by humans and animals and plants, for example, organic substances derived from sweat, cigarettes, perfumes, etc., which pass through the ozone filter. Further, a small amount of organic substances, such as organic substances originating from toner, machine oil, etc., released during operation of the device equipped with the ozone filter also passes through the ozone filter. Some of the organic substances that have come into contact with the ozone filter are oxidized and decomposed as they are or by the action of manganese dioxide and ozone, and then adsorbed by manganese dioxide and accumulate on the filter.

[0007] These organic substances have no problem if they are adsorbed by manganese dioxide, even if they are substances with strong odor. It is believed that some of these odors combine to give an unpleasant odor because they are released into the atmosphere in the air. Accordingly, an object of the present invention is to provide a method for improving an ozone filter using an active manganese dioxide catalyst having excellent ozone decomposability so that it does not give off a bad smell even after long-term use.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a fine powdered active manganese dioxide catalyst and a zeolite powder having a SiO ₂ / Al ₂ O ₃ ratio (molar ratio) of 15 or more together with a high porosity inorganic fiber paper carrier. was achieved by Rukoto is supported on.

[0009] SiO ₂ / Al ₂ O ₃ ratio of 15 or more zeolites used here, or SiO ₂ / Al ₂ O ₃ ratio is used in desiccant showed a strong hydrophilicity is normal zeolite of about 2-15 On the contrary, it is known that it has an ability to adsorb hydrocarbon compounds better than water vapor (hereinafter, this zeolite having strong hydrophobicity is referred to as hydrophobic zeolite). The composition of a representative example is HAlSi ₃₅ O ₇₂ , H
AlSi ₂₅ O ₅₂ (see Japanese Patent Application Laid-Open No. 60-501495 and JP-A-1-31457). Commercially available products that are easily available include those having a SiO ₂ / Al ₂ O ₃ ratio of about 50 to 500.

[0010] Manganese dioxide is used as the powder of the hydrophobic zeolite.
An ozone filter obtained by being supported on a carrier together with a catalyst does not give off a bad smell even when used for a long time. Although the reason has not yet been elucidated, the fact that the hydrophobic zeolite adsorbs any of the organic substances in the atmosphere after or before oxidation with ozone in the vicinity of the manganese dioxide catalyst releases odor-causing substances. It is presumed to have helped to prevent it.

[0011]

Hereinafter, a method for preventing the generation of offensive odors according to the present invention will be described.
It will be described in detail . The manganese dioxide used as the ozonolysis catalyst is not particularly limited, and may be a commercially available product or any product produced by an arbitrary production method. Particularly preferred is a particle size of 0.3 to 50 μm and a specific surface area of 0.3 to 50 μm. 150
It is a fine powdered active manganese dioxide of m ² / g or more. This fine powdered active manganese dioxide can be uniformly supported on a carrier made of inorganic fiber paper in a large amount and even to the carrier core. Such a finely powdered manganese dioxide catalyst having a large specific surface area is prepared by, for example, allowing an aqueous solution of an oxidizing agent such as hypochlorite or permanganate to act on a suspension of manganese carbonate in water to produce a manganese dioxide. A method in which the precipitate is treated with an acid and neutralized with an alkali (Japanese Patent Publication No. 55-84).
No. 56) and the like.

As the hydrophobic zeolite, those having the above-mentioned composition having a particle size of about 1 to 10 μm are preferably used.

[0014] A carrier comprising a high porosity inorganic fiber paper supporting a manganese dioxide catalyst and a hydrophobic zeolite is described, for example, in JP-A-59-10345. That is, it is made of inorganic fiber such as alumina fiber, silica-alumina fiber, glass fiber, rock wool and the like.
A paper having a high porosity of about 95% and a honeycomb structure obtained by processing the paper. "Hanicle" (a product of Nichias Co., Ltd.)
There is. The porosity is a value obtained from the following equation. Porosity (%) = (1−apparent density / true density) × 100

The thickness of the paper is not particularly limited, but is most preferably about 0.1 to 0.4 mm.

The honeycomb-structured carrier made of inorganic fiber paper is most suitable for efficiently treating a large air volume of air to be treated with low pressure loss, and is a carrier of a manganese dioxide catalyst for treating low-concentration ozone-containing air. As excellent. In addition, since it can be cut, any shape and size can be easily manufactured, and there is a feature that it does not crack even if dropped. Preferred honeycomb structures have an effective surface area of 8 to 40 cm ² / cm ³ (particularly preferably 20 to 40 cm ² / c
m ³ ), an aperture ratio of 50 to 90% (particularly preferably 50 to 70%)
%)belongs to.

In order to support finely powdered active manganese dioxide and hydrophobic zeolite on the above-mentioned carrier, an inorganic binder such as silica sol, alumina sol, titania sol, or a mixture thereof is added to a suspension of active manganese dioxide and hydrophobic zeolite. What is necessary is just to impregnate the carrier by immersion or coating with the addition, and to dry it. At this time, the amount of the binder used is desirably limited to a necessary minimum. If the binder is used in excess, the surface of the manganese dioxide is covered and the catalytic activity is reduced. If it is difficult to fix the required amount of catalyst at one time, the catalyst impregnation and drying are repeated until an appropriate amount of catalyst is fixed. The preferred supported amount of hydrophobic zeolite is diacid
About 15-40 parts by weight per 100 parts by weight of manganese oxide catalyst
It is. Insufficient amount of hydrophobic zeolite produces odor
Cannot be completely prevented. On the other hand,
Limit the amount of supported manganese dioxide catalyst.
It tends to inhibit the ozonolysis activity of the catalyst.

The active manganese dioxide and the hydrophobic zeolite may be prepared by separately preparing a suspension to which a binder has been added, and carrying one of the suspensions after the impregnation / fixing treatment.

When the manganese dioxide catalyst and the hydrophobic zeolite are supported on the carrier, a part of the interfiber space of the paper is left as a void, so that the remaining porosity, that is, the porosity after the catalyst and the zeolite are supported. When the porosity calculated according to the calculation formula is about 50 to 85%, the air to be treated easily diffuses to the surface of the catalyst fixed to the core of the paper constituting the carrier, and the utilization rate of the manganese dioxide catalyst is improved.

[0020]

【Example】

Example 1 A paper having a thickness of 0.1 mm and a porosity of 90% made of silica-alumina fiber having a fiber diameter of 2 to 3 μm and a small amount of an organic binder was processed into corrugated paper and corrugated with an unprocessed flat paper. The honeycomb structure carrier having 560 / in ² cells was obtained by alternately stacking the contacts and bonding the contacts with a silica-based adhesive.

On the other hand, a precipitate formed by reacting an aqueous solution of manganese sulfate and an aqueous solution of sodium carbonate is washed with water and dried, and 1 kg of manganese carbonate obtained is suspended in 2000 ml of water, heated to 60 ° C. and stirred. The sodium hypochlorite aqueous solution was added little by little while adding. As a result, manganese carbonate reacted while generating carbon dioxide gas and changed to black manganese dioxide. After the completion of the reaction, the formed precipitate of manganese dioxide was filtered, washed with water and dried. The obtained manganese dioxide powder had a specific surface area of 220 m ² / g and an average particle size of 5 μm.

100 parts by weight of the above manganese dioxide powder, 30 parts by weight of a hydrophobic zeolite (SiO ₂ / Al ₂ O ₃ = 150), and 100 parts by weight of silica sol (solid content: 30% by weight) were mixed with 200 parts by weight of water. The resulting slurry was added to the above honeycomb structured carrier (dimensions: cell opening surface 100 mm × 100).
mm, 15 mm in the ventilation direction) and dried. Then, by repeating the above immersion and drying once more,
An ozone filter having a manganese dioxide loading of 46 g / m ² , a hydrophobic zeolite loading of 14 g / m ² , and a residual porosity of 70% was obtained.

COMPARATIVE EXAMPLE 1 A catalyst slurry prepared in the same manner as in Example 1 except that hydrophobic zeolite was not added was subjected to the same loading treatment as in Example 1 to obtain an ozone filter having a manganese dioxide loading of 46 g / m ^2. Manufactured.

Next, the ozone resolution of the ozone filters of the above examples was examined by the following method. Test method: Ozone-containing air obtained by treating dehumidified air with a silent discharge type ozone generator was diluted with clean air to obtain a gas to be treated having an ozone concentration of 0.5 ppm, a temperature of 27 ° C. and a relative humidity of 80%. Prepare. The gas to be treated is converted to a space velocity of 280,000 / H
In r, the cell is kept flowing through the ozone filter arranged so that the cell opening surface of the honeycomb structure carrier is perpendicular to the ventilation direction. After a lapse of a predetermined time, the outlet side air is sampled and the ozone decomposition rate (by the following formula) is measured. Ozone decomposition rate (%) = (inlet ozone concentration−outlet ozone concentration) × 100 / inlet ozone concentration

The measurement results are as follows. The ozone decomposing ability of the product of the embodiment in which the hydrophobic zeolite was mixed and supported was slightly lowered, but it was confirmed that the ozone resolving power was sufficient for practical use.

Next, a test was carried out to compare the number of copies leading to the generation of offensive odors by attaching the ozone filter to the electrostatic recording type copier and continuously using the same. At the time of copying the sheets, an odor was felt, but the machine equipped with the product of the example did not feel the odor even after copying 180,000 sheets.

[0027]

As described above , according to the present invention , the amount of
Long-term use of ozone filters using gun catalysts
Also, it is possible to prevent the generation of a bad odor, and it is possible to maintain a favorable working environment around the equipment that generates ozone.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-7038 (JP, A) JP-A-4-313320 (JP, A) JP-A-3-42016 (JP, A) 10345 (JP, A) JP-A-5-23591 (JP, A) JP-A-63-7844 (JP, A) JP-A-5-261294 (JP, A) JP-A-3-8447 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) B01D 53/86 B01J 21/00-38/74 B01D 39/00-39/20

Claims (1)

(57) [Claims] A fine powdered active diacid having ozone decomposability
Manganese oxide supported on a carrier made of inorganic fiber paper with high porosity
When manufacturing an ozone filter with
SiO ₂ / Al ₂ O ₃ with powdered active manganese dioxide
Supporting a zeolite powder having a ratio of 15 or more on a carrier
Prevents offensive odor from the ozone filter
Way.