JP2000126551A - Photocatalyst filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photocatalyst filter that is excellent in light transmission characteristic and low in pressure loss of a gas to be treated passing through the photocatalyst filter. SOLUTION: This filter 1 comprises a fiber porous body 2 using a large number of silica fibers 21 having intersections 211 thereof connected with each other by an inorganic binder 23 and titanium oxide particles 3 fixed to the silica fibers 21, and is of a type wherein a gas to be treated is made to pass through the fiber porous body 2. The fiber porous body 2 has a porosity of 90-98% and a mean pore diameter of 40-100 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst filter used for an air purifier or the like and for decomposing odor components and the like.

[0002]

2. Description of the Related Art For example, it has been proposed to use a photocatalyst as an environmental material for removing odors or the like (Japanese Unexamined Patent Publication No. Hei 8-
99041). As for an air purifier, a photocatalyst filter that decomposes odor components and the like in the air using a photocatalyst has been proposed. The photocatalyst filter supports a photocatalyst component such as TiO _{2 on} a sheet-like material, irradiates light, and allows air, which is a gas to be processed, to pass through the photocatalyst filter to adsorb and decompose odorous components.

[0003] In such a sheet-shaped photocatalytic filter, it is necessary to first irradiate the photocatalytic component with more light. Further, the gas to be treated such as air needs to efficiently pass. As the sheet-shaped photocatalytic filter, a photocatalytic component may be supported on an alumina cordierite ceramic foam.

[0004]

However, such a ceramic foam has an insufficient light transmittance, so that the catalytic performance of the photocatalytic filter is low. Further, when a gas to be treated such as air is passed through the photocatalytic filter, a small pressure loss is required from the viewpoint of treatment efficiency. Further, the photocatalyst filter is required to have excellent durability without the photocatalyst component carried on a substrate such as a ceramic foam being detached from the substrate.

Further, as shown in FIG. 10, a photocatalyst filter 9 in which a photocatalytic component is supported on a ceramic honeycomb structure has been proposed. However, in this case, the light applied to the photocatalyst filter 9 is transmitted in parallel to the hole direction of the honeycomb, but is not transmitted in other directions, and the light is not sufficiently applied to the photocatalyst component. Further, the flow of the gas to be treated in the photocatalyst filter 9 is linear along the honeycomb hole direction. Therefore, the contact probability between the gas to be treated and the photocatalyst component is low. As described above, the catalytic performance of the conventional photocatalytic filter is not sufficient.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a photocatalyst filter having excellent light transmittance and low pressure loss of a gas to be processed passing through the photocatalyst filter. It is.

[0007]

According to the first aspect of the present invention, there is provided a porous fibrous body comprising a large number of silica fibers and their intersections bonded to each other by an inorganic binder, and titanium oxide particles fixed to the silica fibers. A photocatalyst filter of a type that allows the gas to be processed to pass through the porous fibrous body, wherein the porous fibrous body has a porosity of 90% to 98%.
%, Having an average pore diameter of 40 to 100 μm.

The most remarkable point in the present invention is that the porous fiber body is made of silica fiber, and the porosity and the average pore diameter are within the above specific ranges. The above porosity is
This is the ratio of the voids of the porous fiber to the unit volume. The average pore diameter refers to an average of the diameters of a large number of pores formed between the silica fibers in the porous fibrous body. More precisely, assuming a circle having an area equivalent to the opening area of the pore, the average of the diameters of the circle is the average pore diameter.

When the porosity is less than 90%, the pressure loss of the gas to be treated passing through the photocatalytic filter is high,
There is a possibility that the processing capacity is reduced and the catalyst performance becomes insufficient. On the other hand, if the porosity exceeds 98%, sufficient strength as a filter may not be obtained.

When the average pore diameter is less than 40 μm, the pressure loss of the gas to be processed passing through the photocatalyst filter is high, the processing capacity is reduced, and the catalyst performance may be insufficient. On the other hand, when the average pore diameter is 100 μm
If the ratio exceeds, the contact probability between the gas to be treated and titanium oxide is reduced, and the catalytic performance may be insufficient.

Next, the operation and effect of the present invention will be described.
The porous fiber body in the photocatalytic filter of the present invention is made of silica fibers. Since the silica fiber is excellent in light transmittance, the photocatalyst filter itself is also excellent in light transmittance.

The porous fiber has a porosity and an average pore diameter within the above specific ranges. Therefore, light easily enters the inside of the photocatalytic filter, and the light entering inside is irregularly reflected. Further, the irregularly reflected light irradiates the inside of the photocatalytic filter having a high porosity. In addition, silica fibers have excellent light transmittance. Therefore, the titanium oxide particles as the photocatalytic component in the photocatalytic filter are efficiently irradiated, and the catalytic performance is improved.

Further, since the photocatalyst filter has the porosity and the average porosity as described above, the pressure loss of the gas to be processed passing through the photocatalyst filter is low. Therefore, the gas to be processed efficiently passes through the photocatalyst filter, so that the catalytic performance is sufficiently exhibited.

As described above, according to the present invention, it is possible to provide a photocatalyst filter having excellent light transmittance and low pressure loss of a gas to be processed passing through the photocatalyst filter.

[0015] The thickness of the photocatalyst filter is 0.1 mm.
It is preferably from 5 mm to 3.0 mm. Thereby, the catalytic performance of the photocatalyst filter is sufficiently exhibited. If the thickness is less than 0.5 mm, the amount of titanium oxide particles coming into contact with the gas to be treated passing through the photocatalytic filter is small, and odor components and the like cannot be sufficiently removed. In addition, the strength of the filter itself becomes insufficient. On the other hand, when the thickness exceeds 3.0 mm, the pressure loss of the gas to be processed passing through the photocatalytic filter is high,
The catalyst performance may be insufficient.

Next, the titanium oxide particles preferably have a particle size of 0.5 to 50 μm. As a result, odor components and the like in the gas to be processed passing through the photocatalytic filter can be efficiently decomposed. If the particle size of the titanium oxide particles is less than 0.5 μm, the titanium oxide particles may fall off the filter. On the other hand, if the particle size exceeds 50 μm, the pressure loss of the gas to be processed passing through the photocatalytic filter may increase.

Next, as in the third aspect of the present invention, the amount of the titanium oxide particles per unit volume of the porous fibrous body is preferably 0.005 to 0.06 g / cm ³ . As a result, odor components and the like in the gas to be processed passing through the photocatalytic filter can be efficiently decomposed. The loading amount of the titanium oxide particles is 0.005 g / cm.
If it is less than ^3, the catalytic performance of the photocatalytic filter may be insufficient. On the other hand, when the amount of
If it exceeds 6 g / cm ³ , the pressure loss of the gas to be processed passing through the photocatalyst filter increases, so that the processing capacity may be reduced and the catalyst performance may be insufficient.

Next, as in the invention according to claim 4, the crystal system of the titanium oxide particles is either anatase, rutile or a mixture of both. Among them, in the case of anatase, since the photoactivity is high, the catalytic performance of the photocatalytic filter is particularly excellent.

Next, as in the invention according to claim 5, the porous fibrous body contains reinforcing fibers together with the silica fibers, and their intersections are bonded to each other by the inorganic binder. It is preferred that As a result, the strength of the porous fiber body is improved, and a photocatalytic filter having excellent durability can be obtained.

Next, as in the invention according to claim 6, the inorganic binder is preferably either borosilicate or aluminoborosilicate. Thereby, a photocatalyst filter having high strength can be obtained. Further, unlike the case where an inorganic binder containing an alkali metal such as water glass is used, there is no possibility that Na dissolves in titanium oxide and lowers the activity as a photocatalyst.

Next, it is preferable that the titanium oxide particles are sintered and fixed to the silica fiber. Thereby, the titanium oxide particles are more securely fixed to the silica fibers, and there is no possibility of falling off. Therefore, a photocatalyst filter having more excellent durability can be obtained.

In the present invention, the gas to be treated includes room air in houses and buildings, vehicle room air, toilet air, factory exhaust gas, and refrigerator air.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A photocatalytic filter according to an embodiment of the present invention will be described.
This will be described with reference to FIGS. As shown in FIG. 1, the photocatalyst filter 1 of the present embodiment uses a large number of silica fibers 21 and has a crossing point portion 211 of which is bonded to each other by an inorganic binder 23 (FIG. 1B). It comprises titanium oxide particles 3 sintered and fixed to the silica fibers 21 (FIG. 1 (A)). The photocatalyst filter 1 is of a type that allows a gas to be processed to pass through the porous fiber body 2.

The porous fiber 2 has a porosity of 90%.
% To 98%, and the average pore diameter is 40 to 100 μm. The thickness of the photocatalyst filter 1 is 0.5 mm to 3.0 mm.
0 mm. The titanium oxide particles 3 have a particle size of 0.5 to 50 μm, and are supported on the porous fibrous body 2 by 0.005 to 0.06 g / cm ³ per unit volume.

Further, the fiber porous body 2 contains reinforcing fibers 25 together with the silica fibers 21, and their intersections 211 are bonded to each other by the inorganic binder 23. As the inorganic binder 23, either borosilicate or aluminoborosilicate is used.

Next, the operation and effect of this embodiment will be described. The porous fiber body 2 in the photocatalytic filter 1 of the present embodiment is made of silica fibers 21. Since the silica fibers 21 are excellent in light transmittance, the photocatalyst filter 1 itself is also excellent in light transmittance.

The porous fiber 2 has a porosity and an average pore diameter within the above-mentioned specific ranges. Therefore, FIG.
As shown in (1), light 4 easily enters the inside of the photocatalytic filter 1, and the light 4 entering inside is irregularly reflected. Further, the irregularly reflected light 4 irradiates the inside of the photocatalytic filter 1 having a high porosity. Thereby, since the titanium oxide particles 3 as the photocatalyst component in the photocatalyst filter 1 are efficiently irradiated, the catalytic performance is improved.

Since the photocatalyst filter 1 has the porosity and the average porosity as described above, the pressure loss of the gas to be processed passing through the photocatalyst filter 1 is low. Therefore, the gas to be processed efficiently passes through the photocatalyst filter 1, so that the catalytic performance of the photocatalyst filter 1 is sufficiently exhibited.

The porous fiber 2 contains reinforcing fibers together with the silica fibers 21. Therefore, the strength of the porous fiber body 2 is improved, and the photocatalyst filter 1 having excellent durability can be obtained. In addition, since the titanium oxide particles 3 are fixed to the silica fibers 21 by sintering, the titanium oxide particles 3 are more securely fixed to the silica fibers 21 and do not fall off. Therefore, a photocatalytic filter having excellent durability can be obtained.

As described above, according to this embodiment, it is possible to provide a photocatalytic filter having excellent light transmittance, low pressure loss of the gas to be processed passing through the photocatalytic filter, and excellent durability.

Experimental Example 1 This is an example in which the photocatalytic filter of the present invention was evaluated for deodorization. First, the method for manufacturing the photocatalytic filter used in this example will be described separately for the method for manufacturing titanium oxide particles and the method for fixing the titanium oxide particles to the porous fiber.

The titanium oxide particles were produced by the sol-gel method described below. First, the humidity in the glove box was adjusted to 20% or less by replacing with nitrogen. Next, in the above glove box, 42.05 g of diethanolamine (DEA) was added to 800 ml of ethanol, and the mixture was dissolved by stirring with a stirrer for 30 minutes.

Then, 113.7 g of titanium tetraisopropoxide (TTIP) was added, and the vessel was sealed.
The mixture was stirred with a stirrer for 5 hours. As a result, the TTI
A titanium oxide sol having a P concentration of 0.5 mol / l was obtained.

Next, a method for fixing the titanium oxide particles to the porous fiber body will be described. The above porous fibrous body processed to a thickness of 2 mm was subjected to a heat treatment at 850 ° C. for 15 minutes to completely remove oil and the like on the surface of the porous fibrous body. Then, an appropriate amount of the above titanium oxide sol solution was poured into a beaker, and the porous fiber was gently charged.

Thirty seconds after the introduction, the porous fibrous body was gently taken out of the beaker, and it was confirmed that there were no droplets falling from the porous fibrous body. The body was fixed by sintering. The heat treatment conditions were Step 1 to Step 5 shown in Table 1.

[0036]

[Table 1]

In Table 1, Step 1 and Step 2
Is a step for evaporating ethanol which is a solvent of the titanium oxide sol. Step 3 and Step 4 are steps for precipitating anatase. In the temperature lowering step of Step 5, when the temperature is rapidly lowered from the holding temperature,
Since there is a concern that the titanium oxide may become amorphous, a slow temperature gradient of 1.5 ° C./min was set.
According to the above-mentioned method, 0.032 g / c of titanium oxide particles
A photocatalyst filter having m ³ fixed was prepared.

The above photocatalytic filter was evaluated for deodorization using ammonia, acetaldehyde, methyl mercaptan and trimethylamine. For comparison, a similar deodorization evaluation was also performed on a conventional honeycomb-shaped photocatalytic filter having titanium oxide particles fixed at 0.032 g / cm ³ .

The evaluation was performed using a deodorizing evaluation device 5 shown in FIG. That is, first, the gas to be treated was injected into a 10-liter tank 51 provided with a stirrer, and adjusted to a predetermined concentration. Next, the photocatalyst filter 1 was disposed in the reactor 55, and the air volume was adjusted by the blower fan 52 so that the wind speed at the front surface 11 of the photocatalyst filter 1 was 0.2 m / sec.

The blower fan 52 is operated to circulate the gas to be treated in the pipe 56 as shown by the arrow G, and at the same time, the photocatalyst filter 1 is irradiated with the light 4 by the ultraviolet lamp 40 of 10 W. Was measured by a gas chromatograph 54. The UV lamp 40 is a black light, and the UV (wavelength: 350 nm) intensity applied to the photocatalyst filter 1 is 0.5 mW /
cm ² .

When the gases to be treated were ammonia (Table 2), acetaldehyde (Table 3), methyl mercaptan (Table 4), and trimethylamine (Table 5), the results measured by the above method were shown in Tables 2 to 5. Shown in The measurement was performed for each gas to be treated 0.5 hours, 1 hour, and 1.5 hours after the operation of the deodorizing evaluation device 5. The measurement was performed five times under the same conditions.

In Tables 2 to 5, the removal rate is a value calculated from the following equation. That is, ｛1- (concentration of gas remaining after a predetermined time [ppm]
/ Concentration of injected gas to be treated [ppm])｝ × 100%. The concentration of the gas to be treated injected into the tank 51 is 510 ppm for ammonia, 455 ppm for acetaldehyde, 570 ppm for methyl mercaptan, and 420 ppm for trimethylamine.

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

As shown in Tables 2 to 5, the photocatalyst filter of the present invention was superior to the conventional photocatalyst filter in deodorizing ability, regardless of the gas to be treated. That is, when the conventional photocatalytic filter was used, the gas to be treated could not be completely removed in one hour, and the gas to be treated remained even after 1.5 hours. On the other hand, when the photocatalyst filter of the present invention was used, it was almost completely removed in one hour, and was surely removed after 1.5 hours.

Experimental Example 2 In this example, as shown in Table 6 and FIGS. 4 to 6, the transmittance and the reflectance when light was irradiated to the porous fibrous body in the photocatalytic filter of the present invention were evaluated. . As the fiber porous body, a lightweight heat-resistant tile material was used.

That is, the transmittance and reflectance when the above-mentioned porous fibers having a thickness of 0.5 mm, 0.8 mm and 1.2 mm were irradiated with light of each wavelength were measured. The measurement results are shown in FIGS. 4, 5, and 6, respectively. Table 6 shows the transmittance and the reflectance when the light having a wavelength of 380 nm was irradiated to the three types of porous fiber bodies.

[0050]

[Table 6]

From Table 6 and FIGS. 4 to 6, it can be seen that the above fibrous porous body clearly has light transmittance. Also,
It can be seen that the reflectance increases as the thickness of the porous fibrous body increases. This result indicates that light once entering the porous fibrous body is scattered and emitted to the outside of the porous fibrous body.

Experimental Example 3 As shown in FIG. 7, this example is an example of an experiment for confirming light scattering inside the photocatalytic filter of the present invention. That is, as the photocatalyst filter of the present invention, a sample in which titanium dioxide particles were dispersed and supported on a porous fiber was prepared. On the other hand, as a comparative example, a sample in which the surface of a slide glass was coated with a thin film of titanium dioxide was prepared.

A method for preparing these samples will be described. First, the titanium oxide sol shown in Experimental Example 1 was used for supporting the titanium oxide particles on each of the above substrates. The base material, that is, the fibrous porous body and the slide glass both used had a size of 50 × 50 × 2 mm.

The slide glass was repeatedly dipped in a titanium oxide sol solution and dried to form a titanium oxide sol layer having a thickness of about 1 μm.
Next, the powder was fired at 500 ° C. for 1 hour and the change in weight was measured. As a result, the supported amount of titanium oxide was 0.020 g.

On the other hand, also for the above porous fiber, 0.0
20 g of titanium oxide was loaded. That is, the porous fiber was dipped in a titanium oxide sol solution, coated, and baked under the same conditions as in the case of a slide glass. At this time, the titanium oxide sol solution was prepared by diluting the titanium oxide sol solution shown in Experimental Example 1 with ethanol so that the amount of titanium oxide carried was 0.020 g.

Next, the evaluation method will be described. First, an aqueous solution of methylene blue having a concentration of 100 ppm is prepared, and 150 cc of the aqueous solution of methylene blue is placed in a quartz glass cell (dimensions 60 × 55 × 5 mm). There, above 2
Two samples, and a distance of 2 with a 500 W mercury lamp
Irradiation was performed from a position 0 cm away.

Then, 10 cc of the methylene blue solution was weighed every predetermined time, and the transmitted visible light was measured with a spectrophotometer. FIG. 7 shows the time-dependent change in the decolorization rate (concentration: 100 ppm) of the aqueous methylene blue solution in each sample obtained by determining the rate of increase in visible light at this time. In addition, as a blank, the time-dependent change in the decolorization amount of the methylene blue aqueous solution when only the light was irradiated without putting the sample in the methylene blue aqueous solution was measured. This result is also as shown in FIG.

FIG. 7 shows that the decomposition rate of methylene blue in the photocatalytic filter of the present invention is about twice that of the sample of the comparative example. This result indicates that the photocatalytic filter of the present invention is superior in catalytic performance to the sample of the comparative example. That is, in the case of the photocatalyst filter of the present invention, light enters deep inside the porous fibrous body and is scattered inside to activate the catalytic performance of more titanium oxide particles. Is represented.

Embodiment 2 This embodiment is an example in which the photocatalytic filter of the present invention is used in the form as shown in FIG. That is, an ultraviolet lamp 40 is arranged inside the photocatalyst filter 1 formed in a cylindrical shape, and the outside of the photocatalyst filter 1 is covered with an outer cylinder 6. A seal 7 is provided at the end of the cylindrical photocatalyst filter 1 so that the gas to be treated does not leak from the end.

The photocatalyst filter 1 constructed as described above
The gas to be treated is injected from the inside of the filter, passed through the photocatalyst filter 1, and discharged to the outside. This decomposes and removes odor components and the like of the gas to be treated. The gas to be processed is injected while irradiating light with an ultraviolet lamp 40. Others are the same as the first embodiment. In FIG. 8, the arrow G indicates the flow of the gas to be processed.

As described above, the photocatalyst filter 1 of this embodiment has the ultraviolet lamp 40 disposed inside. Therefore, light can be irradiated by the ultraviolet lamp 40 without particularly irradiating light from outside. Further, since the ultraviolet lamp 40 is disposed inside the cylindrical photocatalyst filter 1, most of the light emitted from the ultraviolet lamp 40 is irradiated on the photocatalyst filter 1, so that the efficiency is high. .

As described above, the photocatalyst filter 1 includes:
In particular, since light can be efficiently irradiated without externally irradiating light, the photocatalytic filter 1 can easily and efficiently exhibit catalytic performance. The other effects are the same as those of the first embodiment.

Embodiment 3 This embodiment is an example in which the photocatalytic filter of the present invention is used in a form as shown in FIG. That is, a plurality of sheet-shaped photocatalyst filters 1 are stacked with an ultraviolet lamp 40 interposed therebetween.

The gas to be treated is sequentially passed through the plurality of photocatalyst filters 1 while irradiating light with the ultraviolet lamp 40. As a result, the odor components and the like of the gas to be treated are decomposed and removed. Other configurations are the same as those of the first embodiment. In FIG. 9, the arrow G indicates the flow of the gas to be processed.

As described above, the photocatalyst filter 1 of the present embodiment has a plurality of layers stacked, and the ultraviolet lamp 40 is arranged between them. Therefore, similarly to the second embodiment, the photocatalyst filter 1 can be efficiently irradiated with light without particularly irradiating light from the outside. Good catalytic performance can be exhibited. Further, since the gas to be processed passes through a plurality of photocatalyst filters 1, odor components and the like can be more reliably removed. The other effects are the same as those of the first embodiment.

[0066]

As described above, according to the present invention, it is possible to provide a photocatalytic filter having excellent light transmittance, low pressure loss of a gas to be processed passing through the photocatalytic filter, and excellent durability. it can.

[Brief description of the drawings]

FIG. 1A is a partial perspective view of a photocatalytic filter, and FIG. 1B is an explanatory diagram showing a junction at an intersection of silica fibers in the photocatalytic filter.

FIG. 2 is an explanatory diagram showing light scattering inside a photocatalytic filter in the first embodiment.

FIG. 3 is an explanatory diagram of a deodorizing evaluation device in Experimental Example 1.

FIG. 4 is a diagram showing light transmittance and reflectance of a 0.5 mm-thick porous substrate in Experimental Example 2.

FIG. 5 is a diagram illustrating a light transmittance and a reflectance of a porous substrate having a thickness of 0.8 mm in Experimental Example 2.

FIG. 6 is a diagram showing a light transmittance and a reflectance of a porous substrate having a thickness of 1.2 mm in Experimental Example 2.

FIG. 7 is a diagram showing a difference in catalytic performance due to light transmittance between a photocatalytic filter and a comparative example in Experimental Example 3.

FIG. 8 is a perspective view illustrating a usage form of a photocatalytic filter in a second embodiment.

FIG. 9 is a perspective view illustrating a usage form of a photocatalytic filter in a third embodiment.

FIG. 10 is a perspective view of a photocatalytic filter using a honeycomb structure in a conventional example.

[Explanation of symbols]

 1. . . 1. photocatalytic filter, . . 20. porous fiber body, . . Silica fiber, 23. . . Inorganic binder, 25. . . 2. reinforcing fibers, . . 3. titanium oxide particles; . . Light, 5. . . Deodorizing evaluation device,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) B01J 35/10 301 B01J 35/10 301A B01D 53/36 H (74) The above three agents 100079142 Patent Attorney Yoshiyasu Takahashi (1 outsider) (71) Applicant 000001144 Director, Industrial Technology Research Institute 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (74) One of the above-mentioned sub-agents 100079142 Patent Attorney Yoshiyasu Takahashi (2 outsiders) ( 72) Inventor Shinji Kato 3-36 Noritake Shinmachi, Nishi-ku, Nagoya City, Aichi Prefecture Within Noritake Company Limited (72) Inventor Misao Iwata 3-136 Noritake Shinmachi, Nishi-ku, Nagoya City, Aichi Prefecture Noritake Company Limited (72) Inventor Hirokazu Matsunaga 3-36 Noritakeshinmachi, Nishi-ku, Nagoya-shi, Aichi Noriita Co., Ltd. Company Limited (72) Inventor Hiroshi Taota 1-70 Heiwagaoka, Meito-ku, Nagoya City, Aichi Prefecture Inoishi House 4 Building 301 (72) Inventor Toru Nonami 1-70 Heiwagaoka, Meito-ku Nagoya City, Aichi Prefecture No. 302 Inokoishi Residential Building No. 302 F-term (reference) 4C080 AA10 BB02 CC01 CC02 CC05 CC08 CC09 CC12 CC13 CC14 NN01 NN02 NN06 QQ17

Claims (7)

[Claims] 1. A porous fibrous body comprising a large number of silica fibers and their intersections bonded to each other by an inorganic binder, and titanium oxide particles fixed to the silica fibers, and covered with the porous fibrous body. A photocatalytic filter of a type for allowing a processing gas to pass therethrough, wherein the porous fibrous material is
The porosity is 90% to 98%, and the average pore diameter is 40 to 100μ.
m, a photocatalytic filter. 2. The photocatalytic filter according to claim 1, wherein said titanium oxide particles have a particle size of 0.5 to 50 μm. 3. The method according to claim 1, wherein the amount of the titanium oxide particles per unit volume of the porous fibrous body is 0.1.
Photocatalytic filter, which is a 005~0.06g / cm ^3. 4. The method according to claim 1, wherein:
A photocatalytic filter, wherein the crystal system of the titanium oxide particles is either anatase, rutile, or a mixture of both. 5. The method according to claim 1, wherein:
A photocatalyst filter, wherein the porous fibrous body contains reinforcing fibers together with the silica fibers, and their intersections are bonded to each other by the inorganic binder. 6. The method according to claim 1, wherein:
A photocatalytic filter, wherein the inorganic binder is one of borosilicate and aluminoborosilicate. 7. The method according to claim 1, wherein:
A photocatalytic filter, wherein the titanium oxide particles are fixed to the silica fiber by sintering.