JP2002035601A - Photocatalyst structure for cleaning air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst structure capable of continuously and efficiently conducting removal of offensive odors or harmful substances in air, cleaning of the environment or the like. SOLUTION: A plurality of wire-like base bodies, each of which has a surface coated with a titanium oxide film or the like, are implanted at intervals suitable for irradiating the whole wire-like base bodies with light, on a base plate having many ventilation holes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst structure used as an environmental purification material for removing bad smells and harmful substances in the air.

[0002]

2. Description of the Related Art Conventionally, porous substances such as activated carbon and zeolite, so-called adsorption removal, have been generally used as a method for removing odors and harmful substances in the air. However, the adsorbent only has the ability to adsorb most harmful substances, so that the ability stops at a certain amount.

[0003] A photocatalytic filter obtained by processing titanium oxide powder supported on organic fibers by a binder into paper and processing the paper into a honeycomb shape (Japanese Patent Application Laid-Open No. 9-59892).
However, it is inevitable that the organic binder is deteriorated due to the photocatalytic action of titanium oxide over time and the photocatalytic component is gradually released.

In addition, since the honeycomb structure has a small space volume and a short photocatalytic reaction distance, the photocatalytic performance cannot be sufficiently exhibited. Therefore, at present, it is supplemented with an adsorbent such as activated carbon or zeolite.

[0005] Decomposition scum adheres to the filter surface over a long period of use and eventually becomes nitric acid and remains on the surface, degrading the decomposition performance. However, the only way to remove this is to remove the filter from the main body and wash it, which is very inconvenient. Met.

[0006]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention utilizes a photocatalytic action with high efficiency without detachment of photocatalytic components, and removes harmful substances and is safe for environmental purification.
It is an object of the present invention to provide a photocatalyst structure which is excellent in stability, light resistance and economy, and has a performance capable of promptly and effectively decomposing and removing it continuously.

[0007]

In order to achieve the above object, a wire-like substrate having a surface coated with titanium oxide or the like is provided on a substrate provided with a large number of ventilation holes at intervals so that light can be efficiently irradiated. It is characterized by doing. Also, the invention is characterized in that the wire-like substrate is formed integrally with the substrate.

In the photocatalyst structure of the present invention, since the spatial volume corresponding to the length of the wire-like substrate is within the decomposition treatment range, contaminants entering from various directions are decomposed and removed while coming into contact with the surface of the wire-like substrate. As a result, the photocatalytic reaction distance is long and the decomposition efficiency is very high.

The photocatalytic action of titanium oxide is activated by ultraviolet irradiation such as sunlight, a fluorescent lamp, a black light, a UV lamp, a mercury lamp, a xenon lamp, and a halogen lamp, so that the titanium oxide can be decomposed.

The photocatalytic titanium oxide used in the present invention is a semiconductor that irradiates a semiconductor with light to generate electrons having a strong reducing action and holes having a strong oxidizing action to decompose molecules in contact with the semiconductor by the redox action. It is known that titanium oxide, zinc oxide, cerium oxide, metal oxides such as tungsten oxide and the like are known, but titanium oxide is particularly desirable in consideration of photoreactivity and safety in handling. It is desirable that the crystals are crystallized in an anatase shape.

The adsorbent used in the present invention is activated carbon, bincho charcoal,
Activated clay, zeolite, zinc oxide, magnesium oxide, silica, silica zinc oxide composite, silica alumina zinc oxide composite, composite phyllosilicate, and the like. In addition, particles having a specific surface area of 1000 to 3000 m ² / g are preferably used according to the target harmful substance.

The wire-like substrate used in the present invention is made of stainless steel,
Examples include metals such as aluminum and other alloys or inorganics such as ceramics, carbon, and glass, and organics such as plastics. Its shape is circular, angular, elliptical,
There are shapes such as a gourd, circular tube, square tube, elliptic tube, gourd tube, etc., and a circular shape is desirable in consideration of workability and efficiency of the irradiation angle of ultraviolet rays.

[0013] The diameter is several millimeters to several centimeters, and the length is several centimeters to several meters.

The fine fibers having a diameter of several mm or less can be obtained by processing such as twisting, twisting and braiding.

The shape, thickness, length, etc. of the wire-like substrate can be appropriately selected according to the harmful substance to be treated and the treatment environment.

The adsorbent is added to the undercoat material in an amount of 0.1% of the total weight.
A wire-like substrate obtained by mixing 0.5% to 20% of the total weight with the overcoating material and 5% to 20% mixed undercoat and overcoating material can be used for the interior fiber and the minute space of fiber. Due to the presence of the powder, the supplemental ability is further increased.

Further, since the porosity between the fibers is as high as 30% to 55%, the excess paint coated between the fibers enters between the fibers and the titanium oxide powder covers the surface of the wire-like substrate together with the adsorbent, resulting in a very effective area. A photocatalyst structure having a wide range was obtained.

When an antibacterial agent is further contained as required, an inorganic antibacterial agent such as silver, zinc or calcium phosphate, an organic antibacterial agent such as benzimidazole, isothiazoline or pyrithione, or a polymer such as chitin chitosan is used. Antibacterial agents and the like. As a method of incorporating the compound into the wire-like substrate, it may be mixed with titanium oxide or mixed with an adsorbent and applied and impregnated.

When removing harmful substances such as NOx,
When a noble metal such as platinum, rhodium, palladium or the like is coated or mixed on titanium oxide or the like, the photocatalytic reaction of titanium oxide is improved. This is considered to be because electrons generated in the titanium oxide due to light absorption are attracted to the noble metal and recombination with holes is suppressed, so that the remaining holes are affected by the oxidation reaction with the odorant.

When the wire-like substrate thus obtained is a metal or inorganic material, it is coated with a photocatalytic paint (commercially available) containing photocatalytic titanium oxide and a binder component.
It is obtained by calcining the temperature gradually from room temperature to 80 ° C to 400 ° C.

Synthetic fibers, papers, natural fibers of pulp, recycled fibers, etc. are undercoated and gradually heated from room temperature to 60 ° C. to 80 ° C. in order to avoid deterioration of the substrate due to the oxidation-reduction action of titanium oxide. Bake at temperature and allow to cool, then coat with a photocatalytic titanium oxide paint and gradually increase from room temperature to 80 °
It is obtained by firing at an elevated temperature of C to 100 ° C.

Further, plastic organics are also obtained by undercoating and sintering gradually from room temperature to 60 ° C. to 100 ° C. in order to avoid deterioration due to titanium oxide.

The material of the substrate used in the present invention includes organics, metals, and inorganics, which can be appropriately selected and used.

When the photocatalyst material is applied to the photocatalyst structure of the present invention, the photocatalyst titanium oxide may be applied alone or using a commercially available photocatalyst paint containing the photocatalyst titanium oxide and a binder component.

When the wire-like substrate to be applied is organic, it is necessary to apply an undercoat because the deterioration is caused by the oxidative decomposition power of titanium oxide.

Examples of the undercoat material include inorganic adhesives such as laponite, montmorillonite, smectite, and silica, and fluorine resin adhesives such as polytetrafluoroethylene and silicone resin adhesives.

When the wire-like substrate to be applied is a metal such as stainless steel, aluminum or the like, or an inorganic material such as ceramics or glass, a photocatalytic paint may be applied directly, and a further 80
It is obtained by firing at a temperature of from 400C to 400C.

The coating method includes, but is not particularly limited to, a coating method such as a spray method, a dip coating method, a spin coating method, a coating method, a vapor deposition method, and a sputtering method.

Typical examples of the present invention are shown below, but the present invention is not limited to these shapes.

[0030]

Embodiments of the present invention will be described below. (Example 1) Air is introduced from an air inlet 6 provided on the upper side surface of a container in which the upper and lower portions are fixed to a 3 mm thick Pyrex (registered trademark) lid 5 on a vinyl chloride pipe 4 having a straight 140 mm height and a 140 mm height. Is injected into the test reaction vessel provided with an outlet for purified air from an air outlet 7 provided on the bottom side face, and a 10 mm space between the PTFE tetrafluoroethylene substrate 2 having a diameter of 140 mm and a thickness of 6 mm. To 4
A vent hole 3 having a diameter of 1 mm is provided, and a hole 1 mm in diameter is formed around the vent hole 3.
1mm in diameter and 6mm in the hole
A photocatalyst structure in which a 0 mm stainless steel wire-like substrate 1 was implanted was manufactured.

The undercoating photocatalytic paint (Okitsumo NO6950P) is applied to the stainless steel wire-like substrate 1 by a spray method, then naturally dried, and gradually dried from room temperature to 80 °.
C. and heat for 10 minutes. After natural cooling, a top coat (Okitsumo NO 6950T) is applied by a spray method, and then naturally dried.
The temperature was raised to ° C. and baked for 20 minutes.

This photocatalyst structure was set in a test reaction vessel and subjected to a NO decomposition / removal test. The test method was as follows: irradiating 15 w of black light from above, NO was injected from the air inlet 6 at a concentration of 0.96 PPM to 194 ml.
/ Min, and the concentration contained in the air outlet 7 was analyzed using a NOx removal performance test apparatus using a potentiostatic electrolytic sensor. As a result, the NO concentration was 95% in 5 minutes.
Decreased (Figure 5)

(Example 2) 2 m excluding the circumference of a PTFE tetrafluoroethylene substrate 2 having a diameter of 140 mm and a thickness of 6 mm
Open the vent holes 3 from end to end with a width of m. It is applied to the entire surface at intervals of 4 mm, and holes of 2 mm diameter are made in the remaining portion at intervals of 4 mm. A mixture of acrylic fiber with a fiber density of 7 denier and a fifteen denier half is bundled in the holes, impregnated with melamine resin, baked and dried, and an acrylic fiber device obtained is straight through 2 mm length 60 mm porosity 55% Asahi fiber A test photocatalyst structure was manufactured by upright planting an industrial product as a wire-like substrate 1.

The photocatalyst structure is coated with an undercoat photocatalyst paint (Okitsumo 7005P) by a spray method, then dried, heated from room temperature to 80 ° C., and gradually baked for 20 minutes. After natural cooling, 5% of Bincho charcoal powder (Masudaya) as an adsorbent was mixed with a top coat paint (Okitsumo 7005T) as a sorbent by 5% mixing and spray coating. After drying, the temperature was gradually raised from room temperature to 80 ° C. Baking for 20 minutes.

The photocatalyst structure was set in the same reaction vessel for testing as in Example 1 and a NO decomposition removal test was performed. While irradiating the photocatalytic structure with 15 w of black light from above, NO was continuously flown from the air inlet at a concentration of 0.75 PPM at a flow rate of 400 ml / min, and the concentration of NO contained in the air outlet was measured using a potentiostatic electrolytic sensor. N used
The analysis was performed using an Ox removal performance test apparatus. The result is N
The O concentration decreased 100% in 3 minutes. (FIG. 6)

(Example 3) A comparative example with another company is as follows. Straight through 14 with a honeycomb photocatalytic filter made of paper made by Company D
Set 0mm height 10mm in the test reaction vessel and set N
O decomposition removal test was performed. While irradiating 15w of black light from the top, 1.04 NO from the air inlet
The PPM was continuously flowed at a flow rate of 400 ml / min, and the NO concentration at the air outlet was determined by using a potentiostatic electrolytic sensor.
The analysis was performed using an x removal performance test apparatus. NO concentration is 1
At 0 minutes, it decreased by 90%. (FIG. 7)

[0037]

According to the present invention, as described in detail above, in this photocatalyst structure, the spatial volume corresponding to the length of the substrate is within the decomposition treatment range, so that contaminated air comes into contact with the surface of the wire-like substrate to oxidize the photocatalyst. Since the environmental pollutants are continuously decomposed and purified with high efficiency by the photocatalytic action of titanium, it is effective in various fields such as gradually removing floating bacteria in hospitals, restaurants, station premises, etc., and removing harmful substances in tunnels and factories. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a perspective view of a photocatalyst structure of the present invention.

FIG. 2 is a cross-sectional side view showing a state in which a photocatalyst structure is set in a test reaction container.

FIG. 3 is a perspective view of a photocatalyst structure according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a honeycomb filter of a third embodiment manufactured by another company.

FIG. 5 is a graph showing the results of a performance evaluation test of Example 1 of the present invention.

FIG. 6 is a graph showing the results of a performance evaluation test of Example 2 of the present invention.

FIG. 7 is a graph showing the results of a performance evaluation test of Example 3 made by another company.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wire-like base | substrate 2 Substrate 3 Ventilation hole 4 Vinyl chloride pipe 5 Lid 6 Air inlet 7 Air outlet a Black light

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 53/86 ZAB B01D 53/36 H 53/94 ZABJ B01J 21/06 102C

Claims (2)

[Claims] 1. A photocatalyst for air purification, wherein a large number of wire-like substrates, the surfaces of which are covered with a titanium oxide film or the like, are implanted on a substrate provided with a large number of ventilation holes at intervals at which light can be efficiently irradiated. Structure (hereinafter referred to as photocatalyst structure) 2. The photocatalyst structure according to claim 1, wherein the wire-like substrate and the substrate are integrally formed.