JP2003024748A - Photocatalytic reaction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalytic reaction apparatus having the sufficiently high decomposition capacity of gas to be treated and reducing the pressure loss of the gas to be treated passed through the photocatalytic reaction apparatus. SOLUTION: Photocatalyst particles 4 are stored in a reaction tank 1 in which the gas to be treated is allowed to flow and optically excited while floated in the reaction tank 1 to be brought into contact with the gas to be treated to treat the gas to be treated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalytic reaction device that operates with ultraviolet rays or the like.

[0002]

2. Description of the Related Art In recent years, with increasing interest in environmental pollution, there is an increasing demand for removal of malodorous substances and air pollutants in daily life. In order to meet these demands, air purifiers, ventilation fans, etc. incorporating an odor decomposition device have been proposed.

In these devices, a catalytic combustion system, an activated carbon adsorption system, etc. are generally adopted. However, in the case of the catalytic combustion method, although the treatment is surely performed, the electric power usage fee may increase as the treatment amount increases.
Further, in the case of the activated carbon adsorption method, although the running cost is low, since the adsorption mechanism is the main mechanism and there is no decomposition action, the removal capacity may become insufficient when the adsorption amount of activated carbon is saturated.

As a method of avoiding the above problems, a photocatalytic reaction device such as an odor decomposition device utilizing the excellent organic substance decomposition action of a photocatalytic semiconductor compound has been proposed. When the photocatalytic semiconductor compound is irradiated with light having a wavelength having an energy larger than the band gap, it produces electrons in the conduction band and holes in the valence band. These electrons and holes act on water and oxygen on the surface of the photocatalyst to generate active oxygen such as superoxide ion and hydroxyl radical, and decompose the organic matter by its strong oxidizing action.

Since the photocatalytic reaction is a surface reaction, in order to efficiently decompose organic substances in the photocatalytic reaction apparatus, the surface area of the reaction field is increased and the photocatalytic semiconductor compound is decomposed into odorous substances. Need to contact efficiently.

[0006] As such an attempt, Japanese Patent Laid-Open No. 9-225
Japanese Laid-Open Patent Publication No. 263 describes a structure in which the surface area is increased by coating the honeycomb-shaped material with titanium oxide. Further, Japanese Patent Laid-Open No. 10-15393 describes a structure in which glass beads coated with titanium oxide are packed in a container, and a gas to be processed passes through the gap.

[0007]

However, the method described in Japanese Patent Laid-Open No. 9-225263 has the advantage that the pressure loss of the gas to be treated can be reduced, but since the reaction field has a honeycomb structure, it is excited. In some cases, the entire reaction field may not be efficiently irradiated with light, and the treatment may be insufficient.

Further, in the method described in Japanese Patent Application Laid-Open No. 10-15393, the glass beads coated with titanium oxide are filled in a container, and the substance to be treated passes through the gap, so that sufficient treatment capacity is realized. In addition, when the bead diameter is reduced and the surface area is increased, the pressure loss of the gas to be processed passing through the gap may increase.

On the other hand, if the diameter of the beads is increased to reduce the pressure loss and the volume of the reaction vessel is increased to secure a sufficient surface area, the provisional glass beads are transparent to the excitation light of titanium oxide, which is a photocatalyst. Even if it has, since the excitation light transmittance of titanium oxide itself is low, it may become difficult to excite titanium oxide as the distance from the excitation light source increases, and the treatment of the gas to be processed passing therethrough may be incomplete. There is.

In view of the above situation, it is an object of the present invention to provide a photocatalytic reaction device which has a sufficiently high decomposition performance for the gas to be processed and has a small pressure loss of the gas to be processed passing through the photocatalytic reaction device. And

[0011]

According to the present invention for achieving the above object, photocatalytic particles are stored in a reaction tank into which a gas to be treated is introduced, and the photocatalytic particles are photoexcited. At the same time, there is provided a photocatalytic reaction device characterized by treating the gas to be treated by being suspended in the reaction tank and coming into contact with the gas to be treated.

As the photocatalytic particles, those having a photocatalytic semiconductor substance bound to the surface of the carrier particles are used.

In the present invention, the photocatalytic particles stored in the reaction tank of the photocatalytic reaction apparatus are photoexcited, and at the same time, at least a part of the particles is floated when the gas to be processed passes and is brought into contact with the gas to be processed.

By suspending the photocatalytic particles, the spherical particles coated with the photocatalyst are filled in a container as described in JP-A-10-15393, and the gas to be treated is passed through the gap between the particles. On the other hand, it is possible to reduce the pressure loss accompanying the passage of the gas to be treated.

By suspending the photocatalytic particles,
Excitation light can be uniformly applied to the entire photocatalytic particles. Furthermore,
By suspending the photocatalytic particles, the photocatalyst particles that have been photoexcited and the gas to be processed are sufficiently brought into contact with each other, so that the gas to be processed can be efficiently processed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

FIG. 1 shows an example of assembling a photocatalytic reactor.
FIG. 2 shows the entire shape of the photocatalytic reaction device after assembly.

Filters 2 and 3 are provided at the upper and lower ends of the reaction tank 1. Photocatalytic particles 4 are stored in the reaction tank 1, and at the same time, light having a bandgap energy of the photocatalytic semiconductor material or more is irradiated from a light source 5 to photoexcite the photocatalytic semiconductor material.

The gas to be treated 7 which has flowed into the reaction tank 1 through the lower end filter 3 floats and comes into contact with the photocatalytic particles 4 which are photoexcited, so that it is oxidized and decomposed and flows out from the upper end filter 2. At this time, by suspending the photocatalytic particles 4, the pressure loss of the gas to be treated 7 is reduced.

The floating of the photocatalytic particles is carried out by a method of using an inflow air stream of the gas to be treated, a method of utilizing an air flow stream of the gas to be treated, a method of utilizing vibration, a method of utilizing a magnetic field and the like. It is possible to combine these methods, if necessary.

Above all, it is preferable that the photocatalytic particles are suspended by the gas flow of the gas to be treated, because the pressure loss is particularly small and the structure of the apparatus can be simplified.

(Support Particles) As shown in FIG. 3, the particles 8 supporting the photocatalytic semiconductor material 6 are not particularly limited as long as they can be reliably stored in the reaction tank 1, and the gas to be treated to flow in is not limited. 7 and at least a part of them may float and come into contact with each other. Specifically, it is determined by the inflow pressure of the gas to be treated 7, but spherical particles are preferable to acicular particles for reliable storage, and porous materials or hollow spheres may be used. . Also, spherical particles are preferable from the viewpoint of durability of the particles themselves and prevention of scratches on the inner wall of the reaction vessel.

Examples of preferable materials for the carrier particles 8 include plastics and glass materials, and a material that transmits light having a wavelength that excites the photocatalytic semiconductor substance is particularly preferable from the viewpoint of efficiency of photocatalytic reaction.

In order to carry out the photocatalytic reaction, which is a two-dimensional surface reaction, more efficiently, it is preferable to make the particle size of the carrier particles 8 as small as possible to increase the surface area and facilitate the floating. Therefore, the average particle size of the carrier particles is 10 m.
m or less is preferable, 5 mm or less is more preferable, and 1 mm
The following are more preferable.

On the other hand, in order to surely capture the photocatalytic particles with a filter and store them in the reaction tank and to minimize the pressure loss of the gas to be treated, it is desirable that the particle diameter is large. Therefore, the average particle diameter of the carrier particles is 0.01
It is preferably at least μm, more preferably at least 0.05 μm, even more preferably at least 0.1 μm.

(Photocatalytic particles) Carrier particles 8 shown in FIG.
As the photocatalytic semiconductor material 6 bound to
O ₂, ZnO, SnO₂, SrTiO₃, WO₂, Bi
₂O₃, Fe₂O₃At least one selected from the group consisting of
The above substances are preferable, and titanium oxide is preferred because it is safe and inexpensive.
(TiO₂, Also called Titania) is preferred. Especially the minutes
From the viewpoint of solution performance, anatase type titanium oxide and brookie
Toxoid titanium oxide is particularly preferred.

As a method of binding the titanium oxide which is the photocatalytic semiconductor substance 6 to the carrier particles 8, a method of applying a titanium alkoxide solution to the carrier particles 6 and baking it can be mentioned. In particular, by setting the firing temperature in the range of 450 to 750 ° C., anatase type titanium oxide can be obtained.

On the other hand, when the carrier particles 8 are hollow glass bodies or plastic carrier particles, the carrier particles 8 are heated at the firing temperature.
Since the particles are destroyed or melted, it is preferable to bind anatase type titanium oxide fine particles to the surface of such particles with a binder 9. The binder 9 is a titanium oxide fine particle,
It can function as a matrix and a binder.

The binder 9 is not particularly limited as long as it is a photocatalyst resistant substance that can be formed at a low temperature and reliably binds the photocatalytic substance 6 to the carrier particles 8 and can withstand the organic substance decomposition action of the photocatalytic substance. , Teflon (registered trademark) compounds,
Cured products such as silicone compounds and metal alkoxide compounds are preferred. When these compounds are used, the heat resistance of the carrier particles 8 can be taken into consideration, and the carrier particles 8 can be bound at a lower temperature, and photocatalytic particles can be produced.

Further, the binder 9 is preferably one that transmits light having a wavelength that excites the photocatalytic semiconductor substance 6. When the binder is transparent to photocatalyst excitation light,
The photocatalytic semiconductor material is effectively irradiated with the light from the excitation light source, and the photocatalytic semiconductor material is photoexcited, so that high processing efficiency of the gas to be processed can be realized.

From such a viewpoint, metal alkoxide compounds are particularly preferable, and silicon alkoxide compounds are particularly preferable. By binding the photocatalytic semiconductor substance to the carrier particles with a cured product of a silicon alkoxide compound, photocatalytic particles having excellent photoexcitability can be produced.

(Photocatalytic coating material) Examples of the silicon alkoxide compound used in the present invention include tetraethoxysilane, tetramethoxysilane, tetraisopropoxysilane, tetra-n-propoxysilane and tetrabutoxysilane. You can A photocatalytic semiconductor substance is added to these silicon alkoxide compounds and, if necessary, dissolved or uniformly dispersed in a suitable solvent to prepare a photocatalytic coating material.

The solvent is not particularly limited as long as it dissolves or uniformly disperses the silicon alkoxide compound and the photocatalytic semiconductor substance, but a solvent that easily vaporizes in the drying step is preferable. Specifically, alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol; esters such as methyl acetate and ethyl acetate; ketones such as acetone and methyl ethyl ketone; organics such as benzene, toluene, xylene, pentane, hexane and cyclohexane. A solvent can be illustrated.

Further, water for hydrolyzing the silicon alkoxide compound; acidic catalysts such as hydrochloric acid, sulfuric acid, nitric acid and organic acids; basic catalysts such as ammonia, TEA, pyridine and DMAP may be added.

If necessary, fine powder of activated carbon or zeolite which is an adsorbent, or fine powder of copper or silver which is an antibacterial agent is added to the raw material of the photocatalytic coating film. You can also

FIG. 3 shows a state in which the photocatalytic semiconductor substance 6 is bound to the spherical carrier particles 8 with the binder 9. Here, the amount of the photocatalytic semiconductor substance 6 in the photocatalytic coating material is the amount of the photocatalytic semiconductor substance 6 relative to the total amount of the binder 9 and the photocatalytic semiconductor substance 6 when formed on the surface of the carrier particles 8. Can be specified in.

For example, a silicon alkoxide compound is
When used as a binder raw material, SiO ₂Converted solid content
And the photocatalytic semiconductor material and other solids
The ratio of the photocatalytic semiconductor material to the
From the viewpoint of efficiency, 5% by mass or more is preferable and 10% by mass or less
The above is more preferable, and 15% by mass or more is further preferable. one
On the other hand, the binder ensures that the photocatalytic semiconductor substance is carried on the carrier particles.
95% by mass or less is preferable for the purpose of binding.
0 mass% or less is more preferable, and 85 mass% or less is further preferable.
Good

From the same viewpoint, the mass of the photocatalytic semiconductor substance with respect to the total mass of the SiO ₂ equimolar to the silicon alkoxide compound and the mass of the photocatalytic semiconductor substance is preferably 5% by mass or more. Mass% or more is more preferable and 15 mass% or more is still more preferable. On the other hand, 9
5 mass% or less is preferable, 90 mass% or less is more preferable, and 85 mass% or less is further preferable.

(Production of Photocatalytic Particles) The photocatalytic coating material obtained by mixing the above compounds is prepared by a dip coating method, a spray coating method, a spray drying method or the like.
Coated on spherical particles.

The coating thickness should be determined from the film thickness of the photocatalytic coating film after the binder is cured.
It is expressed as an average film thickness obtained by dividing the volume of the solid content in the coating liquid by the surface area of the carrier particles. The volume of the solid content in the coating liquid is calculated from the mass of the solid content in the coating liquid, assuming that the density of the solid content in the coating liquid is 2 g / cm ³ .

The average film thickness calculated in this manner is preferably 5 nm or more, more preferably 10 nm or more in order to efficiently carry out the photocatalytic reaction. On the other hand, it is preferably 1000 nm or less, and 500 n
It is more preferably m or less.

The spherical particles coated with the photocatalytic coating material are heated and baked to form a photocatalytic coating.
In particular, low heat-resistant spherical particles can be cured at a low temperature by radiation curing or the like.

Thereafter, if necessary, the photocatalytic particles are classified to remove particles having an inaccurate particle size, particle fragments, foreign matters, etc., and stored in the photocatalytic reaction tank.

(Photocatalytic Reaction Device) As shown in FIGS. 1 and 2, the photocatalytic reaction tank 1 for floatingly contacting the gas to be treated 7 and the photocatalytic particles 4 is generally a cylindrical body, and the photocatalytic reaction is carried out. A filter 2 is provided at the upper end of the reaction tank 1 of the apparatus, and a filter 3 is provided at the lower end of the reaction tank 1 of the photocatalytic reaction apparatus. In addition, a fan (not shown) may be provided in the flow path of the gas to be treated 7 communicating with the inside of the reaction tank 1 so that the photocatalytic particles 4 are stably suspended. Further, a light source 5 for photoexciting the photocatalytic particles 4 in the reaction tank 1 is provided to form the photocatalytic reaction device of FIG.

The reaction tank 1 is preferably made of a material that allows the excitation light of the photocatalytic semiconductor material to pass therethrough, such as glass and plastic.

As the filters 2 and 3 provided on the upper and lower ends of the reaction tank 1, a mesh filter or a membrane filter can be used, and the opening diameter is 0.95 times or less the minimum particle diameter of the photocatalytic particles. Preferably 0.9
By setting it to 0 times or less, the photocatalytic particles 4 can be reliably stored in the reaction tank 1 without increasing the pressure loss of the gas to be treated 7.

The diameter and length of the cylindrical body which becomes the reaction tank 1 are optimized by the illuminance of the excitation light to be applied and the flow rate of the gas 4 to be treated.

As shown in FIG. 4, the reaction apparatus as a whole has a structure in which a plurality of excitation light sources 5 surround the reaction vessel 1, or a structure in which a plurality of reaction vessels 1 surround the light source 5 as shown in FIG. You can also

The light source 5 for photoexciting the photocatalytic particles 4 is
Although it is not particularly limited as long as it has energy for photoexcitation, for example, when the photocatalytic semiconductor substance is titanium oxide,
A light source having energy of 3.2 eV or more and light having a wavelength of 380 nm or less is used. As such a light source, a white fluorescent lamp, sunlight, a BLB lamp, a mercury-xenon lamp, a xenon lamp, a high-pressure mercury lamp and the like can be used, but a BLB lamp having a center wavelength around 360 nm is particularly preferable.

The filling rate of the photocatalytic particles 4 filled in the reaction tank 1 is 1% by volume in terms of an apparent volume ratio in order to increase the surface area of the photocatalytic particles 4 as much as possible to enhance the reaction efficiency.
Or more, more preferably 3% by volume or more, and further preferably 5
98% by volume in order to suspend the photocatalytic particles 4 and efficiently contact with the gas to be treated 7 and to irradiate the photocatalytic particles 4 with excitation light evenly.
The amount is more preferably 97% by volume or less, further preferably 95% by volume or less.

The apparent volume ratio (% by volume) means the apparent volume of the photocatalytic particles with respect to the capacity of the reaction layer.

The apparent volume of the photocatalytic particles is
It refers to the bulk volume after the photocatalytic particles have been sufficiently left to stand.

The photocatalytic reaction device described above is an air purifier, a ventilation device, or the like for deodorization, sterilization, purification, etc.
It can be suitably arranged in a filter for removing air pollutants. More specifically, it can be applied to a deodorizing device of a food waste processing machine.

[0054]

The present invention will be described in more detail with reference to the following examples, which are not intended to limit the present invention. Unless otherwise specified below, commercially available high-purity reagents and the like were used.

(Photocatalytic reaction apparatus) As shown in FIGS. 1 and 2, as the photocatalytic reaction tank 1, a reaction tank inner tube 10 and an outer tube 11 made of white plate glass, an upper mesh filter 2 and a lower mesh filter 3 are provided. I used a structure connected by a wire. On the outside of the outer tube 11 of the reaction tank 1, an aluminum ultraviolet reflection plate 12 for preventing ultraviolet leakage and effectively utilizing ultraviolet rays was attached.

The photocatalytic reaction tank 1 has a cross-sectional area of 50 cm.
^{2. The} effective length was 50 cm and the volume was 2.5 liters.

Inside the photocatalytic reaction tank inner tube 10,
A BLB lamp is inserted as the photocatalyst excitation light source 5, an outlet 13 for the gas to be treated 7 is arranged in the upper cap 14, and an inlet 15 for the gas 7 to be treated is arranged in the lower cap 16.

Incidentally, FIG. 6 shows the transmission characteristics 17 of the white plate glass in the ultraviolet and near ultraviolet regions. In addition, FIG. 7 shows that the aluminum reflector is at 45 ° in the ultraviolet and near ultraviolet regions.
The reflective characteristic 18 of

Example 1 (a) Preparation of Photocatalytic Coating Material Tetraethoxysilane (abbreviated as TEOS) manufactured by Kishida Chemical Co., Ltd. was used as a silicon alkoxide compound.
g, Ishihara Sangyo Anatase type titania sol, trade name:
STS-01 (titanium oxide 30.0%, nitric acid 1.82
%, Water 68.0%) and ethyl alcohol 8%
3.1 g was mixed, stirred for 1 hour with a magnetic stirrer and left at room temperature for 1 week to prepare a photocatalytic coating material.

The solid content concentration of this raw material was 5% by mass, of which the titanium oxide content was 57.1% by mass.

(A) Preparation of photocatalytic particles As the carrier particles, a glass balloon manufactured by Fuji Silysia Chemical Ltd., trade name: S-35 (average particle diameter 40 μm, true specific gravity: 0.
35, bulk density 0.24, glass composition was substantially equivalent to white plate glass).

The photocatalyst coating material prepared so that the average film thickness was 100 nm was applied to the carrier particles, and the solvent was volatilized and then baked at 250 ° C. Then, particles having a particle size of 36 μm or less were removed using a filter to prepare photocatalytic particles.

(C) Photocatalytic reaction device A mesh filter having an opening diameter of 30 μ is attached to the lower end of the photocatalytic reaction tank of FIG. 1, and photocatalytic particles having an apparent volume of ¼ of the volume of the photocatalytic reaction tank are charged. A mesh filter having an opening diameter of 30 μ was attached to the upper end of the reaction tank. After that, a reaction device was assembled by using a BLB lamp as a light source, the BLB lamp was turned on, and a 500 ppm methyl acetate air mixed gas was introduced from an inlet at a flow rate of 0.6 L / sec. Then, when the concentration of ethyl acetate from the outlet was measured with a detector tube, it was confirmed that the concentration was reduced to 50 ppm.

The aluminum ultraviolet reflector was removed, and the behavior of the photocatalytic particles at a flow rate of 0.6 L / sec was observed. As a result, it was confirmed that the photocatalytic particles were floating in the reaction tank, and the pressure loss was extremely low. Turned out to be few.

Example 2 The supported particle glass balloon used in Example 1 was replaced with a high speed mixer manufactured by Fukae Kogyo Co., Ltd.
Product name: LFS-GS-2J (internal volume 2L),
Floating flow was carried out at an internal temperature of 40 ° C. The photocatalytic coating material used in Example 1 was spray-coated on this floating glass balloon and dried under reduced pressure.

The apparent input volume of the glass balloon is 1/4 of the internal volume of the high speed mixer used,
The input amount of the photocatalytic coating material was such that the average film thickness of the photocatalytic coating was 100 nm.

Then, the glass balloon coated with the photocatalytic coating material was taken out from the high speed mixer 25.
After curing the photocatalytic coating material at 0 ° C, 36μ with a filter
Particles of m or less were removed to obtain photocatalytic particles.

The same amount of the obtained photocatalytic particles as in Example 1 was put into the reaction tank of the photocatalytic reaction apparatus shown in FIG. Then, the BLB lamp is turned on, and 500p as in the first embodiment.
0.6 L of air containing pm of ethyl acetate was introduced from the inlet.
/ Sec and the concentration of ethyl acetate in the air flowing out from the outlet was measured with a detector tube, and the concentration was lower than the detection limit (25 ppm).

Comparative Example 1 As a photocatalytic coating material, 6.1 g of tetraethoxy titanium (also abbreviated as TEOT) manufactured by Kishida Chemical Co., Ltd., anatase type titania sol manufactured by Ishihara Sangyo Co., Ltd., trade name: STS-01 (titanium oxide) 30.0%,
9.5 g of nitric acid (1.82%, water 68.0%) and 84.4 g of ethyl alcohol were mixed, stirred with a magnetic stirrer for 1 hour and left at room temperature for 1 week to prepare a photocatalytic coating material. This photocatalytic coating material contains the same amount of solids and titanium oxide as those of the photocatalytic coating materials of Examples 1 and 2.

The photocatalytic coating material thus obtained was applied to the supported particle glass balloon used in Example 1 under the same conditions as in Example 2 using a high speed mixer and depressurized. Then, it was baked at 250 ° C. (in this case, the binder is amorphous titanium oxide), and particles having a size of 36 μm or less were removed by using a filter to obtain photocatalytic particles.

The photocatalytic particles obtained were filled in a photocatalytic reaction tank. The apparent volume of the filled photocatalytic particles was set to be the same as the volume of the photocatalytic reaction tank so that the photocatalytic particles would not float in the reaction tank even when gas was introduced from the inlet.

In the photocatalytic reaction tank manufactured as described above, the BLB lamp was turned on, and 500 ppm at the same flow rate.
When ethyl acetate-containing air was introduced and the concentration of ethyl acetate from the outlet was measured with a detector tube, it was a high concentration of 400 ppm.

(Comparative Example 2) The shape of the photocatalytic reaction device is shown in FIG.
The inner tube 10 and the outer tube 11 of the photocatalytic reaction tank 1 were made of soda-lime glass in the same manner as in. This reaction tank was filled with the photocatalytic particles of Example 1. The apparent volume of the filled photocatalytic particles was set to be the same as the volume of the photocatalytic reaction tank so that the photocatalytic particles would not float in the reaction tank even when gas was introduced from the inlet.

In the photocatalytic reaction tank manufactured as described above, the BLB lamp was turned on and 500 ppm at the same flow rate.
The ethyl acetate-containing air was introduced at a flow rate of 0.6 L / sec through the inflow port 15, and the ethyl acetate concentration from the outflow port 13 was measured by a detector tube and found to be 300 ppm.

(Optical Properties of Binder) In order to study the optical properties of the binders used in Examples 1 and 2, the photocatalytic coating material of Examples 1 and 2 was used except that titanium oxide was not mixed. Similarly, a binder coating material was prepared.

That is, the same as in the first and second embodiments,
Ethyl alcohol was mixed so that the molar ratio of water to TEOS was 10.1, the molar ratio of nitric acid as an acidic catalyst to TEOS was 0.08, and the solid content concentration was 5% by mass. After mixing for 1 hour,
The binder coating film raw material was prepared by leaving it at room temperature for one week.

The obtained binder coating material was applied on both sides of white plate glass and baked at 250 ° C. to form a binder film having a thickness of 100 nm.

The transmittance of the thus obtained laminate was measured in the ultraviolet and near ultraviolet regions, and the result is shown in FIG.

Next, in order to examine the optical characteristics of the binder used in Comparative Example 1, the binder coating was performed in the same manner as the photocatalytic coating material of Comparative Example 1 except that titanium oxide was not mixed. The film raw material was adjusted.

That is, TEO should be the same as in Comparative Example 1.
A magnetic stirrer was prepared by mixing ethyl alcohol so that the molar ratio of water to T was 13.3, the molar ratio of nitric acid as an acidic catalyst to TEOT was 0.10, and the solid content concentration was 5% by mass. After mixing for 1 hour at room temperature, the mixture was left at room temperature for 1 week to prepare a binder coating material.

The binder coating material thus obtained was applied to both sides of white plate glass and baked at 250 ° C. to form a binder film having a thickness of 100 nm.

The transmittance of the laminate thus obtained in the ultraviolet and near-ultraviolet regions was measured, and the results are shown at 20 in FIG.

As is clear from FIG. 6, when TEOT is used as the binder, the ultraviolet ray transmittance at a wavelength of 380 nm or less that optically excites titanium oxide is low. By using such a binder, anatase type titanium oxide can be obtained. It can be seen that the photocatalyst is less likely to reach the excitation light, and the action of the photocatalyst to decompose the organic matter is reduced.

Further, 21 of FIG. 6 shows the transmission characteristics of the soda lime glass in the ultraviolet and near ultraviolet regions. Compared with white plate glass,
It can be seen that the transmittance is low. From this, in addition to the transparency of light for exciting the photocatalytic semiconductor substance of the binder, the transparency of the inner tube and outer tube of the reaction vessel, the excitation light transparency of the photocatalyst carrier particles, etc. greatly influences the reaction performance. Conceivable.

Further, from FIG. 7, it is considered that the reflection characteristics of the reflection plate are also important.

Example 3 As support particles, glass beads manufactured by Union Co., Ltd. (particle size: 150 to 250 μm) were used.
φ) was used. This was suspended and flowed in a high speed mixer in the same manner as in Example 2, the photocatalytic coating material of Example 1 was spray-coated and dried under reduced pressure. The average film thickness of the photocatalytic coating film was 100 nm.

Then, the glass balloon coated with the photocatalytic coating material was taken out from the high speed mixer 25.
After curing the photocatalytic coating material at 0 ° C, 100 with a filter
Photocatalytic particles were obtained by removing particles having a size of μm or less.

On the other hand, in the photocatalytic reaction apparatus shown in FIG. 1, the upper filter 2 and the lower filter 3 are 120 μm each.
m, and the photocatalytic particles were charged into the reaction tank 1 so that the apparent volume became 1/4 of the volume of the reaction tank to form a photocatalytic reaction device.

Then, after turning on the BLB lamp, the gas with an unpleasant odor discharged from the exhaust port of the food waste disposer (20 kg disposer) which is actually operating is introduced into the inflow port 15 of the photocatalytic reactor. When connected with a pressure-resistant hose and fed at a flow rate of 5 L / sec, almost no unpleasant odor was felt in the gas from the outlet 13. Further, when the movement of the photocatalytic particles was observed by removing the reflecting plate 12, most of the particles were floating in the reaction tank 1. Furthermore, no abnormality was found in the connection part, the pressure resistant hose, or the like.

Comparative Example 3 The odor from the discharge port of the garbage disposal was treated in the same manner as in Example 3 except that the photocatalytic particles were filled so that the reaction tank 1 was filled. However, the gas from the outlet 13 had an obviously unpleasant odor compared with that of Example 3. It was also found that the pressure-resistant hose connecting the discharge port of the food waste disposer and the photocatalytic reactor expanded, resulting in a large pressure loss.

[0091]

As described above, according to the present invention, when the photocatalytic particles stored in the reaction tank of the photocatalytic reaction device are photoexcited, at least a part of the particles is passed when the gas to be treated passes. With the structure in which the gas is suspended and brought into contact with the gas to be processed, the pressure loss accompanying the passage of the gas to be processed can be reduced, and the decomposition efficiency of the gas to be processed can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view for explaining a state of an example of assembling a photocatalytic reaction device of the present invention.

FIG. 2 is a schematic diagram for explaining an example of a photocatalytic reaction device of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining photocatalytic particles.

FIG. 4 is a schematic diagram for explaining another example of the photocatalytic reaction device of the present invention.

FIG. 5 is a schematic diagram for explaining another example of the photocatalytic reaction device of the present invention.

FIG. 6 is a diagram showing wavelength dependence of transmittance in the ultraviolet and near-ultraviolet regions.

FIG. 7 is a diagram showing wavelength dependence of reflectance in the ultraviolet and near-ultraviolet regions.

[Explanation of symbols]

1 reaction tank 2 filters 3 filters 4 Photocatalytic particles 5 light sources 6 Photocatalytic semiconductor materials 7 Gas to be treated 8 Carrier particles 9 Binder 10 Reaction tank inner tube 11 Reaction vessel outer tube 12 UV reflector 13 Outlet 14 Upper cap 15 Inlet 16 Lower cap 17 Transmission characteristics of white plate glass 18 Reflection characteristics of aluminum reflector 19 Transmission characteristics of binder 20 Permeability of binder 21 Transmission characteristics of blue sheet glass

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Claims (8)

[Claims] 1. A photocatalytic particle is stored in a reaction tank into which a gas to be treated is introduced, and the photocatalytic particle is photoexcited and simultaneously floats in the reaction tank to come into contact with the gas to be treated. The photocatalytic reaction device, wherein the gas to be treated is treated by 2. The photocatalytic reaction device according to claim 1, wherein the photocatalytic particles are suspended by an air flow of the gas to be treated. 3. The photocatalytic reaction device according to claim 1, wherein the photocatalytic particles are formed by binding a photocatalytic semiconductor substance to the surface of carrier particles. 4. The photocatalytic semiconductor material is TiO ₂ ,
The photocatalytic reaction device according to claim 3, wherein the photocatalytic reaction device is at least one substance selected from the group consisting of ZnO, SnO ₂ , SrTiO ₃ , WO ₂ , Bi ₂ O ₃ and Fe ₂ O ₃ . 5. The photocatalytic reaction device according to claim 3, wherein the carrier particles are transparent to the excitation light of the photocatalytic semiconductor material. 6. The photocatalytic reaction device according to claim 3, wherein the photocatalytic semiconductor material is bound to the surface of the carrier particles with a binder. 7. The photocatalytic reaction device according to claim 6, wherein the binder is transparent to the excitation light of the photocatalytic semiconductor material. 8. The photocatalytic reaction device according to claim 7, wherein the binder is a cured product of a silicon alkoxide compound.