JPH08196903A - Porous photocatalyst and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a porous photocatalyst having fine pores with a uniform pore size in the surface, having high environment polluting substance decomposing and removing effects and sustainability of the effects as an environment purifying material to continuously carry out water treatment and malodor removal, and also having excellent properties from the view points of economic properies, safety, water resistance, heat resistance, light resistance, stability, etc., and provide a producing method for the catalyst. CONSTITUTION: A porous optical catalyst is produced by adding polyethylene glycol or polyethylene oxide to a titania sol produced from titanium alkoxides and alcohol amines, applying the obtained mixture to a porous body of such as activated carbon, silica gel, activated alumina, etc., and then heating the resulting body and the crystal structure of a titanium oxide film formed on the surface of the catalyst is anatase. The catalyst adsorbs environment polluting substances efficiently and decomposes and removes the substances quickly, effectively, and even continuously by being rediated with light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous photocatalyst used as an environmental purification material for removing odors, harmful substances in the air, wastewater treatment, water purification treatment and the like, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, foul odors in living spaces and work spaces and pollution by harmful substances such as automobile exhaust gas have become serious problems. In addition, water pollution due to domestic wastewater and industrial wastewater, especially water source pollution due to organic chlorine-based solvents and pesticides at golf courses, which are difficult to treat with currently used water treatment methods such as activated sludge method, etc. Progress is being made and environmental pollution has become a serious social problem.

Conventionally, as a method for preventing malodor or a method for removing harmful substances in the air, a method of absorbing or adsorbing to an absorbent such as acid or alkali, an adsorbent, or soil has been often used. Treatment of waste liquid, used adsorbent and soil may cause secondary pollution. Also,
There are also methods to mask offensive odors by using air fresheners and methods to decompose with activated sludge or ozone.However, in the case of air fresheners, there is a problem of pollution due to the smell of the air fresheners, and in the case of active sludge, treatment The ability is low, and the emission of sludge odor is unavoidable,
Ozone has the drawback of being toxic and costly (eg Konosuke Nishida, Heibonsha "Encyclopedia")
Volume 1, p136 (1984)).

When the semiconductor is irradiated with light, electrons having a strong reducing action and holes having a strong oxidizing action are generated, and the molecular species in contact with the semiconductor are decomposed by the redox action. By utilizing such an action of the semiconductor, that is, a photocatalytic action, it is possible to decompose and remove environmental pollutants such as organic solvents, pesticides and surfactants dissolved in water and harmful substances in the air. This method uses only semiconductors and light, and has less restrictions on reaction conditions such as temperature, pH, gas atmosphere, and toxicity as compared with methods such as biological treatment using microorganisms, and is difficult to treat with biological treatment methods. It has the advantage that even compounds such as organic halogen compounds and organic phosphorus compounds can be easily decomposed and removed. However, in the past research on decomposition and removal of organic substances by photocatalyst, semiconductor powder was used as a photocatalyst (for example, AL Pruden and DF Ollis, Journal of Cat.
alysis, Vol.82, 404 (1983), H. Hidaka, H. Jou, K.
Nohara, J. Zhao, Chemosphere, Vol. 25, 1589 (199
2), Teruaki Kuninaga, Kenji Harada, Keiichi Tanaka, Industrial Water, No. 379
Issue, 12 (1990)). Therefore, it is difficult to handle and use as a photocatalyst, and in the case of water treatment, it is necessary to filter the treated water in order to recover the photocatalyst powder, but since the photocatalyst is a fine powder, it causes clogging and filtration. However, it is difficult to separate and collect the treated product and the photocatalyst, and there is a problem that continuous water treatment cannot be performed.

[0005]

SUMMARY OF THE INVENTION In view of the above, the present invention enables continuous removal of odors and harmful substances in the air, wastewater treatment, water purification treatment, and the like. Excellent decomposition removal effect and its persistence,
Moreover, it is an object of the present invention to provide a porous photocatalyst having excellent properties in terms of economy, safety, weather resistance, and stability, and a method for producing the same.

[0006]

Means for Solving the Problems The present inventor has conducted extensive studies in order to achieve the above object. As a result, polyethylene glycol or polyethylene oxide-added titania sol is coated on the surface of a porous body and then heated and baked. The porous photocatalyst produced by this method has fine pores with uniform pore size on the surface, and efficiently adsorbs organic compounds that pollute the environment such as organic solvents and pesticides dissolved in water, and irradiates light. The inventors have found that the redox action of electrons and holes generated by the method enables rapid decomposition and removal, and the effect can be maintained without maintenance, and the present invention has been completed.

The porous material used in the present invention includes various materials such as porous ceramics, glass and metal. Activated carbon is used in view of the specific surface area and cost.
Activated alumina and silica gel are particularly preferable.

The shape of the porous material used in the present invention may be any shape such as granular, plate-shaped, cylindrical, prismatic, conical, spherical, gourd-shaped, rugby ball-shaped.

The titania sol used in the present invention is prepared by suspending ultrafine particles of titanium oxide in water or hydrolyzing an alkoxide of titanium obtained by a reaction between alcohol and titanium tetrachloride or titanium metal. Is prepared. At that time, monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N,
When alcohol amines such as N-dimethyldiaminoethanol and diisopropanolamine and glycols such as diethylene glycol are added, a uniform and transparent titania sol is obtained, and by using it, a high performance porous photocatalyst can be produced.

The porous photocatalyst of the present invention is prepared by adding polyethylene glycol or polyethylene oxide to the titania sol thus obtained, coating the surface of the porous body by a dip coating method, a dropping method, a coating method, a spray method or the like, and then heating. It is obtained by firing. Here, when polyethylene glycol or polyethylene oxide is not added to the titania sol,
Since the pores on the surface of the porous body are covered with titanium oxide, a porous photocatalyst with a large specific surface area cannot be obtained. By adding polyethylene glycol or polyethylene oxide to titania sol, polyethylene glycol or polyethylene oxide burns and disappears by heating and firing, so pores are formed on the surface of the porous body and connect with the pores, which is a porous photocatalyst with a large specific surface area. Is obtained.

The firing method at that time is that the temperature is gradually raised from room temperature to a final temperature of 600 ° C. to 700 ° C., or firing is performed at a temperature of 400 ° C. to 600 ° C. Is desirable. By this operation, the titania sol coated on the surface of the porous body is changed to titanium oxide whose crystal form is anatase, which has high performance as a photocatalyst. At this time, the firing temperature may be directly 600 ° C. to 700 ° C., or the firing temperature may be lower than 400 ° C.
If the temperature is higher than 0 ° C, only rutile or amorphous titanium oxide having low activity as a photocatalyst can be obtained.

In the porous photocatalyst of the present invention, in order to obtain a strong and high performance titanium oxide film strongly adhered to the porous body, titania sol containing polyethylene glycol or polyethylene oxide is thinly applied or sprayed on the porous body. Alternatively, it is desirable to form a thin film of titanium oxide on the surface of the porous body by coating and then heating and baking it, and repeat this operation to form a multilayer film on the surface of the porous body. Further, when the porous body is activated carbon or the like, it is desirable to use the one in which the surface is made hydrophilic by previously treating the porous body with an acid such as nitric acid, sulfuric acid or hydrochloric acid. By doing so, the titanium oxide film is firmly bonded to the surface, and a high performance porous photocatalyst that is durable and has excellent durability can be obtained.

The polyethylene glycol or polyethylene oxide to be added to the titania sol used in the present invention preferably has a molecular weight of 1,000 or more, and among them, the molecular weight is particularly 1000, 1500, 2000, 3
000, 6000, 8000, 11000, 1300
Those of 0, 20,000, 100,000, 300,000, 2 million, 2.5 million and the like are preferable. When a polymer having a molecular weight of less than 1000 is used, the titanium oxide film formed on the surface of the porous body is easily peeled off from the porous body, and a high performance porous photocatalyst that is durable and has excellent durability can be obtained. Can not.

The amount of polyethylene glycol or polyethylene oxide added to the titania sol used in the present invention is preferably less than its solubility. When it is added at a solubility or higher, pores having a uniform pore size cannot be formed, and a durable and durable titanium oxide film cannot be formed.

The size of the pore diameter and the density of the pore distribution on the surface of the porous photocatalyst of the present invention can be controlled by changing the addition amount or molecular weight of polyethylene glycol or polyethylene oxide. If the amount added is small, or if one with a small molecular weight is used, the porous photocatalyst with small pores on the surface increases the amount added,
When a polymer having a large molecular weight is used, a porous photocatalyst having large pores can be obtained. And, when the addition amount is small, the porous photocatalyst with a sparse distribution of pores has a
When the addition amount is large, a porous photocatalyst with a fine pore distribution is obtained. Moreover, when polyethylene glycol or polyethylene oxide having a wide molecular weight distribution is added, a porous photocatalyst having pores of various pore sizes on the surface can be obtained. Furthermore, by stacking thin films, a porous photocatalyst having a unique three-dimensional structure can be obtained.

In order to further improve the performance of the porous photocatalyst of the present invention, its surface may be coated with a metal film of platinum, rhodium, ruthenium, palladium, silver, copper, zinc or the like. As a method for coating the surface of these metal films,
Photoelectric deposition method, CVD method, PVD method such as sputtering or vacuum deposition, and the like can be mentioned. In this case, if the thickness of the metal film is too thick, it will be costly and it will be difficult for light to reach the titanium oxide thin film. Therefore, it is preferable that the thickness of the metal film is as thin as possible.

The thus obtained porous photocatalyst according to the present invention is porous and has a large specific surface area.
Efficiently adsorbs harmful substances in the air such as Ox, organic solvents dissolved in water, and organic compounds polluting the environment such as pesticides, and sunlight, fluorescent lights, incandescent lights, black lights, UV lamps, It can be decomposed and removed rapidly and continuously by the redox action of electrons and holes generated in the titanium oxide thin film on the surface by irradiation of artificial light from a mercury lamp, a xenon lamp, a halogen lamp, a metal halide lamp or the like. Moreover, by adapting the pore size of the pores on the surface of the porous photocatalyst to the size of the molecule of the environmental pollutant, it can be more efficiently adsorbed and decomposed and removed. The porous photocatalyst according to the present invention can be used at low cost, energy saving, and maintenance-free simply by irradiating light, and platinum or rhodium, ruthenium, palladium, silver, copper, zinc metal on the titanium oxide film. When the film is coated, its catalytic action further enhances the effect of decomposing and removing the organic compound. In this case, since the photocatalyst is porous, the metal is well dispersed and coats the photocatalyst, so that the catalytic action of the metal can be particularly effectively derived.

[0018]

EXAMPLES Among the examples of the present invention, particularly representative ones are shown below.

Example 1 60 g of titanium tetraisopropoxide was diluted with 500 ml of absolute ethanol, 20 g of diethanolamine and 5 g of water were added with stirring, and 5 g of polyethylene glycol having a molecular weight of 1000 was added to obtain a transparent sol solution. It was prepared, and a titanium oxide film was coated on the surface of an activated carbon honeycomb having an 8 cm square and a thickness of 2 cm by the dip coating method. That is, an activated carbon honeycomb was dipped in this sol solution, pulled up, dried, and heated and baked at a temperature of 450 ° C. This was repeated 5 times to form a titanium oxide film on the surface of the activated carbon honeycomb. As a result of investigating the crystal structure of the obtained titanium oxide film by X-ray diffraction, 100% of anatase was obtained.
Met. Also, when the surface was observed with an electron microscope, it was found to be covered with pores having a size of about 10 nm. Using this porous photocatalyst, NOx was decomposed and removed. First, the obtained porous photocatalyst was placed in a closed container having an internal volume of 40 l in which a commercially available 100 W incandescent lamp was set.
After introducing 10 ppm of NOx with a syringe, the incandescent lamp was turned on. After 1 hour, NO contained in the air in the closed container
The concentration of x was measured using a gas chromatograph, and the reduced amount of NOx was injected. As a result of repeating this operation every one hour, when the porous photocatalyst was used, NOx was removed and the concentration was reduced to almost 0 ppm each time. On the other hand, when the activated carbon honeycomb was used instead of the porous photocatalyst, the concentration of NOx was almost 0 ppm at the first time, but as the number of times was increased, the concentration gradually increased, and after 8 times, The value was 10 ppm at the start.

Example 2 45 g of titanium tetraisopropoxide was diluted with 400 ml of absolute ethanol, 15 g of triethanolamine and 4 g of water were added with stirring, and a molecular weight of 1500 was further added.
Was added to prepare a transparent sol solution, and a titanium oxide film was coated on the surface of spherical silica gel having a diameter of about 3 mm by a dropping method. That is,
A small amount of this sol solution was dropped on the surface of the spherical silica gel, the excess solution was dropped and dried, and the temperature was gradually increased from room temperature to 600 ° C.
The temperature was raised up to the temperature of 4 and baked, and this was repeated 5 times to form a titanium oxide film on the surface of the spherical silica gel. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. When the surface was observed with an electron microscope, it was found to be covered with pores having a size of about 20 nm. This porous photocatalyst was used to decompose and remove odorous substances. First, 50 g of the obtained porous photocatalyst was spread in a closed container having an internal volume of 30 l in which a commercially available 100 W black light was set, and 80 ppm of trimethylamine as a malodorous substance was introduced by a syringe, and then the black light was turned on. . After 30 minutes, the concentration of trimethylamine contained in the air in the closed container was measured using a gas chromatograph, and the reduced amount of trimethylamine was injected. As a result of repeating this operation every 30 minutes, when the porous photocatalyst was used, trimethylamine was decomposed and the concentration was reduced to almost 0 ppm each time.
On the other hand, when spherical silica gel was used instead of the porous photocatalyst, the concentration of trimethylamine was 0 at the first time.
Although it was close to ppm, the concentration gradually increased as the number of times was increased, and after 10 times, the concentration was 80 ppm, which was the value at the start.

Example 3 20 g of titanium tetrabutoxide was diluted with 150 ml of t-butyl alcohol, 7 g of triethanolamine and 1.5 g of water were added with stirring, and a molecular weight of 200 was further added.
0.1 g of polyethylene oxide was added to prepare a transparent sol solution, and a titanium oxide film was coated on the surface of spherical activated alumina having a diameter of 6 mm by a coating method. That is, this sol solution was thinly applied to the surface of spherical activated alumina with a brush, dried, and then gradually heated from room temperature to a temperature of 700 ° C. and fired, and this was repeated 6 times to obtain spherical activated alumina. A titanium oxide film was formed on the surface. When the surface of the obtained titanium oxide film was observed with an electron microscope, it was found to be covered with pores having a size of about 1200 nm. The obtained porous photocatalyst was used to decompose and remove acetic acid, which is a malodorous substance. First, 40 g of the obtained porous photocatalyst was spread in a sealed container having an internal volume of 60 l in which ten commercially available 20 W fluorescent lamps were set, 90 ppm of acetic acid was introduced by a syringe, and then the fluorescent lamp was turned on. One hour later, the concentration of acetic acid contained in the air in the closed container was measured by gas chromatography, and the reduced amount of acetic acid was injected. As a result of repeating this operation every hour, acetic acid was decomposed when the porous photocatalyst was used, and the concentration was almost 0 ppm each time.
Had decreased to. On the other hand, when spherical activated alumina was used instead of the porous photocatalyst, the concentration of acetic acid was close to 0 ppm at the first time, but as the number of times increased, the concentration gradually increased, and after 15 times, The value was 90 ppm at the start.

Example 4 Titanium tetraethoxide (25 g) was diluted with methanol (200 ml) and stirred, 8 g of N-methyldiethanolamine and 2 g of water were added, and 0.1 g of polyethylene oxide having a molecular weight of 100,000 was added to give a transparent solution. A sol solution is prepared, and the width is 5 cm, the length is 10 cm, and the thickness is 4 by the coating method.
The surface of the mm activated carbon cloth was coated with a titanium oxide film. That is, a thin coating of this sol solution was applied to the surface of a cloth of activated carbon treated with a 15% hydrochloric acid aqueous solution heated to 70 ° C., dried, and then baked by heating to a temperature of 470 ° C. This was repeated 7 times to activate carbon. A titanium oxide film was formed on the surface of the cloth. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. In addition, when the surface was observed with an electron microscope, it was about 600
It was covered with nanometer-sized pores. The obtained porous photocatalyst was used to decompose trichlorethylene, which is widely used as a solvent and a cleaning agent in the high-tech industry and the cleaning industry and contaminates groundwater and soil, which is a problem. 1
15 ml of an aqueous solution of trichlorethylene with a concentration of 0 ppm
In a test tube made of quartz glass, and the porous photocatalyst 1
After immersing 0 g and bubbling oxygen, the light of a 500 W high-pressure mercury lamp was irradiated. After 1 hour, the amount of trichlorethylene contained in the reaction solution was measured using a gas chromatograph, and a reduced amount of an aqueous solution of trichlorethylene was added. As a result of repeating this operation every one hour, when the porous photocatalyst was used, trichlorethylene was decomposed and the concentration was reduced to almost 0 ppm each time. On the other hand, when the cloth of activated carbon was used instead of the porous photocatalyst, the concentration of trichlorethylene was almost 0 ppm at the first time.
However, as the number of times was increased, the concentration gradually increased, and after 11 times, it was 10 ppm, which was the value at the start.

Example 5 30 g of titanium tetraisopropoxide was diluted with 200 ml of isopropanol, 10 g of diisopropanolamine and 2 g of water were added with stirring, and a molecular weight of 2 was further added.
A transparent sol solution was prepared by adding 0.4 g of polyethylene glycol, and the diameter was 2 mm and the length was 3 by the spray method.
A titanium oxide film was coated on the surface of mm granular silica gel. That is, while spraying the sol liquid while shaking the granular silica gel on a fine wire net, and drying it, the temperature is gradually raised from room temperature to 620 ° C. and fired, and this is repeated 5 times to form the surface of the granular silica gel. A titanium oxide film was made. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. In addition, when the surface was observed with an electron microscope, it was about 350
It was covered with nanometer-sized pores. This porous photocatalyst was used to decompose tetrachlorethylene, which is widely used as a solvent and a cleaning agent in the high-tech industry and the cleaning industry and contaminates groundwater and soil. 10 ml of an aqueous solution of tetrachloroethylene having a concentration of 10 ppm was placed in a test tube made of hard glass, 12 g of the obtained porous photocatalyst was immersed in the test tube, oxygen was bubbled through the tube, and then the light of a 300 W xenon lamp was irradiated. Two hours later, the amount of tetrachloroethylene contained in the reaction solution was measured by using a gas chromatograph, and the reduced amount of tetrachloroethylene aqueous solution was added. As a result of repeating this operation every 2 hours, when the porous photocatalyst was used, tetrachloroethylene was decomposed and the concentration was almost 0 ppm each time.
Had decreased to. On the other hand, when the granular silica gel was used instead of the porous photocatalyst, the granular silica gel was broken into pieces, and the concentration of tetrachloroethylene remained almost unchanged from the initial value.

Example 6 14 g of titanium tetraisopropoxide was diluted with 100 ml of absolute ethanol, 5 g of N-ethyldiethanolamine and 1 g of water were added with stirring, and a molecular weight of 2 was further added.
1g of polyethylene glycol is added to prepare a transparent sol solution, and the diameter is 2mm and the length is 3mm by the dropping method.
The surface of the granular activated carbon of was coated with a titanium oxide film. That is, a small amount of this sol solution was dropped on the surface of granular activated carbon treated with a 10% nitric acid aqueous solution heated to 80 ° C., excess liquid was dropped and dried, and then heated and baked at a temperature of 480 ° C. A titanium oxide film was formed on the surface of the granular activated carbon by repeating 6 times. As a result of investigating the crystal structure of the obtained titanium oxide film by X-ray diffraction, 100% of anatase was obtained.
Met. Also, when the surface was observed with an electron microscope, it was found to be covered with pores having a size of about 50 nm. Acetic acid was decomposed using this porous photocatalyst. 20 ppm
10 ml of an aqueous solution of acetic acid having the above concentration was placed in a quartz container, 5 g of the obtained porous photocatalyst was immersed in the quartz container, oxygen was bubbled, and then the light of a 200 W mercury lamp was irradiated. After one and a half hours, the amount of acetic acid contained in the obtained reaction solution was measured using a gas chromatograph, and an aqueous solution of acetic acid in a reduced amount was added. As a result of repeating this operation every one and a half hours, when the porous photocatalyst was used, acetic acid was decomposed and the concentration was reduced to almost 0% each time. On the other hand, when granular activated carbon was used instead of the porous photocatalyst, the concentration of acetic acid was almost 0 ppm at the first time, but as the number of times increased, the concentration gradually increased, and after 9 times, Is 20pp
It was the value at the start of m.

Example 7 20 g of titanium tetrabutoxide was diluted with 150 ml of t-butyl alcohol, 7 g of triethanolamine and 1.5 g of water were added with stirring, and a molecular weight of 200 was further added.
0.1 g of polyethylene oxide was added to prepare a transparent sol solution, and a titanium oxide film was coated on the surface of spherical activated alumina having a diameter of 5 mm by a spray method.
That is, the sol solution was sprayed onto the sol solution while shaking the spherical activated alumina on a fine wire net, and after drying,
The temperature was gradually raised from room temperature to 650 ° C. and baked, and this was repeated 6 times to form a titanium oxide film on the surface of the spherical activated alumina. As a result of examining the crystal structure of the obtained titanium oxide film by X-ray diffraction, it was found to be 100% anatase. Also, when the surface was observed with an electron microscope, it was found to be covered with pores having a size of about 800 nm. Soak this in an aqueous solution of 2 g / l potassium chloroplatinate in ethanol and stir with a magnetic stirrer to 100
The surface of the titanium oxide film was coated with platinum by photoelectric deposition by irradiating it with light from a W mercury lamp for 1 hour. Using the obtained porous photocatalyst, 4-nitrophenylethylphenyl phosphinate, which is an organophosphorus pesticide, was decomposed. 10
200 ml of an aqueous solution of 4-nitrophenylethylphenylphosphinate having a concentration of 0 ppm was placed in a 300 ml quartz beaker, 10 g of the obtained porous photocatalyst was immersed therein, and oxygen was bubbled, and then the light of a 200 W mercury lamp was irradiated. Irradiated. After 2 hours, the amount of 4-nitrophenylethylphenyl phosphinate contained in the obtained reaction solution was measured by using a gas chromatograph, and the amount decreased was 4
An aqueous solution of -nitrophenylethylphenylphosphinate was added. As a result of repeating this operation every 2 hours, when the porous photocatalyst was used, 4-nitrophenylethylphenylphosphinate was decomposed and the concentration was reduced to almost 0% each time. On the other hand, when spherical activated alumina is used instead of the porous photocatalyst,
The concentration of -nitrophenylethylphenylphosphinate was about 0 ppm, but as the number of times was increased, the concentration gradually increased, and after 10 times, it was 100 ppm, which is the value at the start. The porous photocatalyst coated with a metal film of rhodium, ruthenium, palladium, silver, copper, zinc or the like instead of platinum also showed high decomposition activity.

[0026]

INDUSTRIAL APPLICABILITY As described above, the present invention has the effect of decomposing and removing environmental pollutants such as malodorous substances in the air and organic compounds dissolved in water, and the effect of preventing the growth of fungi and mold and their sustainability. It is an object of the present invention to provide a porous photocatalyst having excellent properties in terms of economy, safety, water resistance, heat resistance, light resistance, weather resistance, and stability, and a method for producing the same. The titanium oxide used in the present invention is also used in paints, cosmetics, toothpaste and the like, and has many advantages such as excellent weather resistance and durability, nontoxicity and safety. Therefore, the porous photocatalyst according to the present invention in which the porous body is coated with titanium oxide has its drawbacks improved even if the porous body of the substrate is weak against water such as silica gel, such as water resistance, weather resistance and durability. Shows excellent characteristics. The porous photocatalyst according to the present invention receives malodor, NOx, SOx due to the redox action of electrons and holes generated in the titanium oxide film upon receiving light from the outside such as an electric lamp or sunlight.
Decomposes harmful substances in the air such as x or organic compounds that pollute the environment such as organic solvents and pesticides dissolved in water, but the concentration of environmental pollutants is low because the photocatalyst is porous However, by adsorbing, it can be decomposed and removed quickly and effectively. Moreover, compared to conventional methods such as ozone treatment, it does not use toxic substances such as ozone, it only needs to be irradiated with light, and light from an electric lamp or natural light can be used, so it is low cost, energy saving, and safe. It is maintenance-free and can be used for a long time. In addition, if the porous photocatalyst is coated with platinum or rhodium, ruthenium, palladium, silver, copper, zinc, etc., the catalytic action further increases the decomposition and removal effect, and the effect is maintained without maintenance.

Further, the porous photocatalyst according to the present invention is effective not only for deodorizing the interior of cars, living rooms, kitchens, toilets, etc., treating wastewater, purifying pools and stored water, but also effectively preventing the growth of bacteria and mold. It can be applied to a wide range of applications. And platinum or rhodium on the titanium oxide film,
When coated with a metal film of ruthenium, palladium, silver, copper, zinc, etc., the metal film has an antibacterial and antifungal action due to its catalytic action, effectively preventing the growth of bacteria and mold on the film. can do.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B01D 53/86 ZAB 53/94 B01J 23/06 ZAB A 23/42 ZAB A 23/44 ZAB A 23/46 ZAB 301 A 311 A 23/50 ZAB A 23/72 ZAB A 35/02 ZAB J C02F 1/30 ZAB B01D 53/36 102 B

Claims (12)

[Claims] 1. A porous photocatalyst characterized in that the surface of a porous body is coated with a titanium oxide film having fine pores of uniform pore size. 2. The surface of a porous body is coated with a titanium oxide film having pores of uniform pore size, and the surface is at least one selected from platinum, rhodium, ruthenium, palladium, silver, copper and zinc. A porous photocatalyst characterized by being coated with the metal film of. 3. The porous photocatalyst according to claim 1 or 2, wherein the porous body is at least one selected from activated carbon, activated alumina, and silica gel. 4. The porous photocatalyst according to claim 1, wherein the pore diameter is 1 nm to 2 μm. 5. The porous photocatalyst according to claim 1, wherein the crystalline form of the titanium oxide porous thin film is anatase. 6. A method for producing a porous photocatalyst, which comprises coating the surface of a porous body with a titania sol to which polyethylene glycol or polyethylene oxide has been added, and then heating and baking the same. 7. A surface of a porous body is coated with titania sol to which polyethylene glycol or polyethylene oxide is added, and after heating and firing, the surface is selected from platinum, rhodium, ruthenium, palladium, silver, copper and zinc. A method for producing a porous photocatalyst characterized by coating with at least one metal film. 8. The method for producing a porous photocatalyst according to claim 6 or 7, wherein the porous body is at least one selected from activated carbon, activated alumina, and silica gel. 9. The method for producing a porous photocatalyst according to claim 6 or 7, wherein polyethylene glycol or polyethylene oxide having a molecular weight of 1000 or more is used. 10. The method for producing a porous photocatalyst according to claim 6, wherein the amount of polyethylene glycol or polyethylene oxide added to the titania sol is not more than its solubility. 11. The method for producing a porous photocatalyst according to claim 6, wherein the titania sol is prepared from titanium alkoxide and alcohol amines or glycols. 12. The method for producing a porous photocatalyst according to claim 6, wherein the surface of the porous body is hydrophilically treated with an acid.