JP2005334734A - Photocatalyst module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst module constituted so as to effectively put the catalytic function of a photocatalyst layer of each of the pore parts of a porous base material to practical use to be enhanced in reaction efficiency. <P>SOLUTION: This photocatalyst module 10 is constituted by integrally forming the photocatalyst layer 3 comprising a photocatalytic substance to the surface of the base material 1 and providing an optical fiber 2 to the base material 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photocatalyst module applied to an air purification device and a water purification device.

  Photocatalysts are attracting attention in environmental fields such as air purification technology and water treatment technology.

  Since photocatalyst can directly use sunlight or fluorescent lamps as an energy source, it has the advantages of wide application range and environmental friendliness, and is an effective technology for application to environmental devices.

When light of a wavelength with energy greater than the band gap is given to the optical semiconductor particle, electrons existing in the valence band are photoexcited and moved to the conduction band, and holes are formed in the valence band. Is done. The excited electron (e ⁻ ) reacts with oxygen to generate a superoxide anion (.O ₂ ⁻ ), and the hole reacts with water to generate a hydroxy radical (.OH).

This superoxide anion (.O ₂ ⁻ ) has a strong reducing power, and the hydroxy radical (.OH) has a strong oxidizing power. Utilizing this strong oxidizing power and reducing power to make harmful substances harmless, it is expected to be applied in the environmental field.
Japanese Patent Laid-Open No. 2-107339 JP-A-8-103631

  However, the reaction rate in the photocatalyst is generally not rapid, and there is room for improvement in terms of reaction efficiency.

As a technique aiming at high efficiency of this photocatalytic reaction, for example, there is one described in JP-A-9-262482, which includes Cr, V, Cu, Fe, Mg, Ag, Pd, Technology for improving the reaction efficiency of a catalyst by a photocatalyst containing at least one metal ion selected from Ni, Mn and Pt at a rate of 1 × 10 ¹⁵ ions / g-TiO ₂ or more on the surface or inside of titanium oxide Is disclosed.

  Japanese Patent Laid-Open No. 2-107339 discloses a technique for improving the catalyst efficiency by forming a catalyst structure by supporting a photocatalytic substance on a base material having a three-dimensional structure through which a reaction gas and light can flow. Has been.

  Furthermore, in the photocatalytic technique described in JP-A-8-103631, a titania sol or titania sol prepared from titanium alkoxide and alcohol amines is applied to a glass filter formed by fusing a spherical heat-resistant glass. A technique for improving the catalytic reaction efficiency using a photocatalyst produced by coating polyethylene glycol or polyethylene oxide and gradually increasing the temperature from room temperature to about 600 ° C to 700 ° C is disclosed.

  However, a photocatalytic technology that utilizes the photocatalytic function to achieve sufficient efficiency as an environmental purification technology has not been proposed.

  Further, it is preferable that the surface area of the base material which is a catalyst carrier is as large as possible. Therefore, in order to obtain a large surface area with a small volume, a photocatalyst module based on a porous body having a large specific surface area is used.

  However, when irradiating light to the photocatalyst module, sufficient light is not supplied to the pores of the porous substrate, and even if a substrate having a large surface area is used, the photocatalytic reaction is mainly performed on the outer surface portion of the substrate. The photocatalyst layer in the base material hole was not utilized.

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a photocatalyst module in which the catalytic function of the photocatalyst layer in the pores of the porous substrate is effectively utilized and the reaction efficiency is improved. And

  In order to solve the above-described problems, the photocatalyst module according to the present invention is a photocatalyst module in which a photocatalyst layer made of a photocatalyst material is integrally formed on the surface of the base material. An optical fiber is provided in the part.

  According to the photocatalyst module according to the present invention, by providing the base material with the optical fiber, light is introduced into the base material hole, and the photocatalytic function in the hole is utilized. Accordingly, it is possible to provide a photocatalyst module with improved photocatalytic reaction efficiency.

  The photocatalyst module and the manufacturing method thereof according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing a fine portion of a photocatalyst module 10 which is a first embodiment of the photocatalyst module of the present invention.

  The photocatalyst module 10 is configured by disposing an optical fiber 2 on a substrate 1 and forming a photocatalyst layer 3 (titanium oxide film) on the surface of the substrate 1.

  The base material 1 is configured by, for example, forming a material having a porous structure such as cordierite into a three-dimensional sponge structure.

  In this way, by forming the base material 1 by further forming the porous material in a three-dimensional sponge structure, the specific surface area of the base material 1 is increased, and a large catalyst contact area can be obtained with a small volume.

  Further, by using the base material 1 having a three-dimensional sponge structure, the flow of gas or liquid flowing through the base material 1 is disturbed, and the chance of contact between the photocatalyst layer 3 and the substance to be decomposed is increased. improves.

  The joining point of the base material 1 and the optical fiber 2 is joined by a joining method such as heat treatment.

  In this photocatalyst module 10, light irradiated from the outside passes through the optical fiber 2 and reaches the inside of the hole 1 a of the base 1, so that not only the outer surface 1 b of the base 1 but also the hole 1 a. However, photocatalytic reactions occur.

  Therefore, a catalyst mechanism in the pores of the porous substrate that has not been used in the conventional photocatalyst module can be used, so that the apparent reaction rate using the photocatalyst can be improved.

  In particular, the photocatalyst module 10 has a bottomed hole 1a, a narrow opening, a large internal volume of the hole, a case where the hole 1a has a branched shape, and the like. Light irradiation is possible even at places where irradiation is difficult, and the catalyst efficiency is greatly improved.

  The present inventors further verified the effect brought about by arranging the optical fiber in the photocatalytic module.

  An optical fiber (made of silicon oxide) and a non-light-transmitting fibrous material (silicon carbide fiber) prepared for comparison are placed on the base material to create a photocatalyst module. Compared.

  First, an optical fiber 2 (made of silicon oxide, diameter 0.1 mm, length 3 mm) was placed and bonded to a base material 1 in which a porous material made of cordierite (low thermal expansion ceramics) was formed in a three-dimensional sponge structure. Dip coating was performed on the base material 1 using a titanium oxide sol having a concentration of 30% and crystal particles of 6 nm, and a photocatalyst layer 3 was formed on the surface of the base material 1 to prepare a photocatalyst module. Then, it baked in air | atmosphere on 550 degreeC temperature conditions for baking for 1 hour.

  After this heat treatment, the cross section of the photocatalyst module was observed with a scanning electron microscope. As a result, it was confirmed that a homogeneous photocatalyst layer 3 of titanium oxide was formed on the surface of the substrate 1, and the film thickness was about 1 μm. It was.

  On the other hand, the photocatalyst modules used for comparison were all photocatalyst modules under the same conditions except that the material of the optical fiber was silicon carbide (for example, diameter 0.1 mm, length 3 mm).

The photocatalytic purification performance of ammonia gas was evaluated using both photocatalyst modules. In the evaluation method, each photocatalyst module was irradiated with black light (average wavelength: 370 nm, intensity: 3 mW / cm ² ), and ammonia gas (initial concentration: 200 ppm) was circulated at a flow rate of 1 liter / min. The gas concentrations were compared.

  FIG. 2 shows the outlet ammonia gas concentration by each photocatalyst module. The lower the ammonia concentration at the outlet, the more efficiently the ammonia gas was decomposed by the photocatalyst.

  As apparent from FIG. 2, when the photocatalyst module having the silicon carbide fiber disposed thereon was used, the ammonia gas concentration was about 60 ppm, whereas the exit ammonia of the photocatalyst module having the silicon oxide optical fiber disposed on the substrate. The gas concentration was almost 0 ppm, and ammonia gas was efficiently decomposed by the photocatalyst, which revealed the superiority of the photocatalyst module in which the optical fiber was arranged.

  This is because, in the photocatalyst module of this example, the light irradiated from the outside is guided to the hole of the base material by the optical fiber arranged on the base material, and the photocatalyst is not only at the outer surface of the base material but also at the hole. This is because of the decomposition of ammonia gas.

  Since the optical fiber is a long fiber, it is introduced following the bottomed shape of the base material hole. For this reason, light is efficiently irradiated to the photocatalyst of a hole part, and it is possible to utilize the catalyst performance of a photocatalyst layer to the maximum.

  In addition, in the photocatalyst module which has arrange | positioned the optical fiber, 10%-50% of the volume fraction of a base material is preferable. When the volume fraction of the substrate is less than 10%, the area for providing the photocatalytic layer is reduced. On the other hand, if the volume fraction of the substrate is greater than 50%, the pressure loss when the fluid passes through the photocatalyst module increases, and the reaction efficiency decreases.

  On the other hand, in the photocatalyst module in which the optical fiber is disposed, the volume fraction of the optical fiber is preferably 30% or less. When the volume fraction of the optical fiber exceeds 30%, the pressure loss when the fluid passes through the photocatalyst module increases, and the reaction efficiency decreases.

  Next, the optical transparency of the optical fiber that improves the photocatalytic performance of the photocatalyst module was investigated.

The conditions of the catalyst test were as follows: a photocatalyst module using optical fibers having different light transmittances was irradiated with black light (average wavelength 370 nm, intensity 3 mW / cm ² ), and ammonia gas (initial concentration 200 ppm) was flowed at 1 liter / min. The outlet concentration of ammonia gas was compared.

  FIG. 3 shows the test results about the influence of the optical transmittance of the optical fiber on the photocatalytic reaction.

  As shown in FIG. 3, when the light transmittance is 0%, light is not introduced into the hole of the base material, so that the catalytic function of the photocatalyst layer other than the outer surface of the base material cannot be utilized. When the light transmittance is 20%, the outlet ammonia gas concentration is reduced to about 70 ppm as compared with the case where the light transmittance is 0%, and the decomposition action of the ammonia gas by the catalyst is improved. If the light transmittance is 30%, it is reduced to about 40 ppm, and if the light transmittance is 40% and 60%, the concentration of the outlet ammonia gas is reduced to about 30 ppm and 20 ppm, respectively, and the catalytic reaction becomes more efficient. It became clear.

  Therefore, the light transmittance of the optical fiber arranged in the photocatalyst module is set to 30% to 100%.

  Next, the optimum condition regarding the shape of the optical fiber 2 in this photocatalyst module was verified.

  First, for an optical fiber having a diameter of 0.3 mm, optical fibers having three lengths of 5 mm, 10 mm, and 15 mm are prepared, arranged on a base material, and bonded to the base material. Dip coating was performed using the titanium oxide sol, and a photocatalyst layer 3 was formed on the surface of the base material to produce a photocatalyst module.

The test condition was that ammonia gas (initial concentration 200 ppm) was circulated at a flow rate of 1 liter / min while irradiating the photocatalyst module with black light (average wavelength 370 nm, intensity 3 mW / cm ² ), and compared the outlet concentration of ammonia gas. did.

  FIG. 4 shows a comparison result of the catalyst performance with the optical fibers having different lengths.

  As is apparent from the results shown in FIG. 4, when the length of the optical fiber is 5 mm, the outlet ammonium gas concentration is 10 ppm or less, and the provision of the optical fiber improves the efficiency of decomposition of ammonia gas by the photocatalyst. Is done.

  When the length of the optical fiber is longer than 5 mm, the decomposition efficiency due to the photocatalytic action tends to decrease. For example, when the length of the optical fiber is 10 mm, the outlet ammonia gas concentration increases to about 20 ppm, and when the length of the optical fiber is 15 mm, the outlet ammonia gas concentration increases to about 40 ppm.

  This is because, when the length of the optical fiber exceeds 10 mm, the optical fiber is a long fiber, so that the optical fibers are entangled with each other and cannot be made into an optimum shape for transmitting light into the photocatalyst layer. It is.

  Therefore, in the photocatalyst module, the upper limit of the length of the optical fiber disposed on the substrate is set to 10 mm or less.

  When the diameter of the optical fiber is 10 mm or less, the change in the outlet ammonia concentration is gradual, and the relationship between the size of the optical fiber and the base material hole and the purpose of arranging the optical fiber in the base material hole are considered. The lower limit of the optical fiber length was 0.5 mm.

  On the other hand, the influence of the diameter of the optical fiber on the photocatalytic reaction was also investigated.

That is, optical fibers having a length of 5 mm and a diameter of 0.3 mm, 0.5 mm, and 0.7 mm were prepared, arranged on the base material, and bonded. Dip coating was performed on this substrate using a titanium oxide sol having a concentration of 30% and crystal particles of 6 nm, and a photocatalyst layer was formed on the surface of the substrate to prepare a photocatalyst module. While irradiating this photocatalyst module with black light (average wavelength 370 nm, intensity 3 mW / cm ² ), ammonia gas (initial concentration 200 ppm) was circulated at a flow rate of 1 liter / min, and the outlet concentration of ammonia gas was compared.

  As a result, as shown in FIG. 5, when the diameter of the optical fiber was 0.3 mm, the outlet ammonia concentration was decomposed to 10 ppm or less. Even when the diameter of the optical fiber was 0.5 mm, the outlet ammonia concentration was about 20 ppm, and the reaction by the catalyst was promoted.

  However, when the diameter of the optical fiber is larger than this, the flexibility is lowered, and it becomes impossible to follow the pores of the photocatalyst layer. When the diameter of the optical fiber is 0.7 mm, the optical fiber is disposed on the base material. It became impossible.

  Therefore, in the photocatalyst module of the present invention, the upper limit of the diameter of the optical fiber is set to 0.5 mm (500 μm).

  When the diameter of the optical fiber is 0.5 mm or less, the change in the outlet ammonia concentration is gradual, and the lower limit of the diameter of the optical fiber is set in consideration of the restrictions on the manufacturing of the optical fiber and the optical transparency of the optical fiber. It was 1 μm.

  Next, the correlation between the structure of the substrate and the photocatalytic performance of the photocatalytic module was verified.

  First, the porosity of the substrate was examined.

  Since the porosity of the base material is closely related to the surface area of the base material, the catalyst performance can be further improved by setting the optimal porosity for the photocatalyst module.

  FIG. 6 is a graph showing the relationship between the porosity of the substrate and the catalyst efficiency.

  As is apparent from the results shown in FIG. 6, as the porosity increases to 10%, 20%, and 40%, the outlet ammonia gas concentration is reduced and the catalyst performance is improved, but the porosity is increased to 80%. %, The outlet ammonia gas concentration was 40 ppm, indicating an upward trend.

  Further, if the porosity is further increased, the mechanical strength of the substrate may be lowered.

  Therefore, in the photocatalyst module of this example, the porosity of the base material was set to 70% or less.

  In consideration of the merit of using a porous material for the base material, the lower limit of the porosity of the base material was set to 10%.

  Next, the relationship between the structure of the substrate and the catalytic performance of the photocatalytic module was verified.

  The case where the base material of the photocatalyst module was composed of a three-dimensional sponge structure member formed of a porous material was compared with the case where the base material was formed of a metal mesh.

The method for evaluating the catalyst performance is to place an optical fiber on each base material and join it, dip coating using a 30% concentration titanium oxide sol with crystal particles of 6 nm, and form a photocatalytic layer on the surface of the base material. A photocatalyst module was created. While irradiating this photocatalyst module with black light (average wavelength 370 nm, intensity 3 mW / cm ² ), ammonia gas (initial concentration 200 ppm) was circulated at a flow rate of 1 liter / min, and the outlet concentration of ammonia gas was compared.

  As is apparent from the results shown in FIG. 7, the photocatalyst module in which the base material is made of a porous material has a concentration of about 50 ppm at the outlet ammonia gas of the photocatalyst module in which the base material is a metal mesh material. The outlet ammonia gas concentration was reduced to 10 ppm or less, and it became clear that the ammonia gas was efficiently decomposed.

  That is, by making the base material a three-dimensional sponge structure member made of a porous material, the specific surface area is increased, and the catalyst of the hole portion can be used by an optical fiber. Can be provided.

  Next, the material of the base material of the photocatalyst module was investigated.

  That is, a photocatalyst module having a base material made of cordierite and a photocatalyst module having a base material made of iron were prepared and evaluated for corrosion resistance.

  In the evaluation method, each photocatalyst module prepared by performing dip coating using a titanium oxide sol having a concentration of 30% and a crystal particle size of 6 nm on each base material and forming a photocatalyst layer on the surface of the base material is converted to a 0.1 mol hydrochloric acid aqueous solution. It was dipped in and the amount of corrosion was compared.

  FIG. 8 shows the corrosion amount of the photocatalyst module using the iron substrate and the photocatalyst module using the cordierite substrate when the corrosion amount of the photocatalyst module using the cordierite substrate is 1. A comparison result is shown.

  As is clear from the results shown in FIG. 8, the corrosion amount of the photocatalyst module using the base material made of cordierite is 1, whereas the corrosion amount of the photocatalyst module using the base material made of iron is about 50. That is, the amount of corrosion of the photocatalyst module using the base material made of cordierite is suppressed to several tenths compared with the photocatalyst module using the base material made of iron, and cordierite is used as the base material of the photocatalyst module. The advantage of using is clear.

  The material of the base material can be a material mainly composed of alumina.

  Since alumina is an inexpensive material with excellent durability, the production cost of the photocatalyst module can be reduced by making a substrate using this alumina.

  FIG. 9 is a graph comparing the amount of corrosion between a photocatalyst module having a base material made of alumina as a main component and a photocatalyst module having silicon nitride.

  As is clear from the results shown in FIG. 9, when the corrosion amount of the photocatalyst module using the base material made of alumina as the main component is 1, the corrosion amount of the photocatalyst module using the silicon nitride base material is assumed. Is about 10. That is, a base material made of a material mainly composed of alumina is very excellent in corrosion resistance as compared with a base material made of silicon nitride, and is suitable as a base material for a photocatalyst module.

  Next, the relationship between the film thickness of the photocatalyst layer and the photocatalytic performance of the photocatalyst module was verified.

  In the photocatalyst module, the film thickness of the photocatalyst layer was set to 0.05, 0.1, 1, 8, and 15 μm, respectively, and the photocatalytic efficiency of each photocatalyst module was compared.

The evaluation method circulates ammonia gas (initial concentration 200 ppm) at a flow rate of 1 liter / min while irradiating a photocatalyst module having a photocatalyst layer of each thickness with black light (average wavelength 370 nm, intensity 3 mW / cm ² ). Then, the outlet concentration of ammonia gas was compared.

  FIG. 10 shows a graph comparing the outlet ammonia concentrations for the photocatalyst modules of the photocatalyst layers of the respective film thicknesses.

  As shown in FIG. 10, when the film thickness is 0.05 μm, the outlet ammonia concentration is about 50 ppm, and the outlet ammonia concentration tends to decrease as the film thickness increases. When the film thickness is 0.1 μm, the thickness is reduced to 20 ppm, and when the film thickness is 1 μm, the thickness is reduced to about 10 ppm. Furthermore, when the film thickness is 8 μm, ammonia is almost decomposed at about 5 ppm, and a good result is shown.

  However, when the film thickness is increased, the photocatalytic performance tends to decrease. For example, when the film thickness is 15 μm, it increases to about 40 ppm.

  From this, the film thickness of the photocatalyst layer formed in a photocatalyst module was set to 0.1 micrometer-10 micrometers.

  Next, the correlation between the particle size of the titanium oxide particles and the photocatalytic performance of the photocatalyst module when the photocatalyst layer was formed on the substrate by dip coating was investigated.

  FIG. 11 is a graph showing the correlation between the particle diameter of the titanium oxide particles and the outlet ammonia gas concentration.

  As is apparent from the results shown in FIG. 11, the smaller the particle size of the titanium oxide particles, the lower the outlet ammonia concentration, and the better the tendency.

  When the particle size of the titanium oxide particles is 0.1 μm or less, the change in the outlet ammonia concentration is gradual, but when it exceeds 0.1 μm, the outlet ammonia concentration tends to increase.

  This is because the specific surface area increases as the particle size of the titanium oxide particles decreases, and the reactivity of the photocatalyst layer improves.

  Therefore, the upper limit of the particle diameter of the titanium oxide particles when forming the photocatalyst layer in the photocatalyst module is set to 0.1 μm (100 nm).

  When the particle size was 0.1 μm or less, the change in the outlet ammonia concentration was gradual, and the improvement in the catalyst performance due to the difference in particle size was not significant.

  Accordingly, the lower limit of the particle size of the titanium oxide particles when forming the photocatalyst layer in the photocatalyst module is set to 0.01 μm in view of the balance between the particle size of the manufacturable titanium oxide particles and the production cost.

  On the other hand, ultrafine titanium oxide of 0.01 μm (10 nm) or less may be aggregated and used in the photocatalyst layer. The correlation between the particle size of the titanium oxide particle aggregate and the catalytic performance of the photocatalyst layer was investigated.

  FIG. 12 is a graph showing the correlation between the particle size of the titanium oxide particle aggregate and the catalyst performance of the photocatalyst module.

  As is apparent from the results shown in FIG. 12, in the titanium oxide particle aggregate, the smaller the particle size, the better the catalytic performance of the photocatalyst module.

  That is, when a titanium oxide particle aggregate is used, it has a larger specific surface area than a single titanium oxide particle of the same volume, and therefore has a larger particle size than a single titanium oxide particle and a highly efficient catalyst in the photocatalyst layer. Performance can be provided.

  Further, by using titanium oxide particle aggregates, the surface shape becomes complicated, and the adhesion to the substrate is improved in the process of forming the photocatalyst layer.

  However, when the particle size of the secondary particles is 0.2 μm or more, the specific surface area is not sufficient, and it is difficult to obtain a homogeneous photocatalyst layer when forming the photocatalyst layer.

  Therefore, the upper limit of the particle diameter of the titanium oxide particle aggregate when forming the photocatalyst layer in the photocatalyst module was set to 0.2 μm (200 nm).

  In the case of a particle size of 0.2 μm or less, the change in outlet ammonia concentration was gradual, and the improvement in catalyst performance due to the difference in particle size was not significant.

  Therefore, the lower limit of the particle diameter of the titanium oxide particle aggregate when forming the photocatalyst layer in the photocatalyst module is set to 10 nm in consideration of the particle diameter of the manufacturable titanium oxide particles and the production cost.

  The optical transparency of the optical fiber varies depending on the material of the optical fiber. Therefore, the effect of the optical fiber material on the catalytic performance of the photocatalyst module was compared and the optimum material was examined.

An optical fiber made of silicon oxide (SiO ₂ ) and an optical fiber made of plastic were prepared, and the catalytic performance of the photocatalyst module prepared using each optical fiber was compared and evaluated.

The evaluation method circulates ammonia gas (initial concentration 200 ppm) at a flow rate of 1 liter / min while irradiating a photocatalyst module created using each optical fiber with black light (average wavelength 370 nm, intensity 3 mW / cm ² ). Thus, the outlet gas concentration of ammonia gas was compared.

  FIG. 13 shows a graph comparing the catalyst performance when each optical fiber is used.

  As apparent from the results shown in FIG. 13, the ammonia concentration at the outlet of the photocatalyst module using the silicon oxide optical fiber was reduced to about 10 ppm, whereas in the case of the photocatalyst module using the plastic optical fiber, The ammonia concentration was about 50 ppm.

  This is because an optical fiber made of silicon oxide has a property excellent in light transmittance as compared with an optical fiber made of plastic.

  In addition, silicon oxide has a good transmittance for near-ultraviolet light, and also has excellent adhesion to a titanium oxide film. Therefore, a stable titanium oxide film can be formed.

  Therefore, by using an optical fiber made of silicon oxide, the photocatalyst in the porous base material hole can be used more effectively.

  On the other hand, it is possible to improve the photocatalytic efficiency by adding an adsorbent or metal particles to the titanium oxide particles.

  FIG. 14 is a graph comparing the catalyst efficiency when a metal element is added to titanium oxide and the catalyst performance of the photocatalyst module when no additive titanium oxide is used.

  As is apparent from the results shown in FIG. 14, in the case of a photocatalyst module without addition of a metal element, the outlet ammonia concentration is about 20 ppm, but in the case of a photocatalyst module to which a metal element is added, almost no ammonia is detected, and the catalyst performance. Is improved.

  The photocatalyst module of the present invention contains at least one selected from Au, Ag, Ru, Rh, Pd, Os, Ir, and Pt as a metal element.

  When these metal elements are added to the photocatalyst layer in combination of one or several metal elements, the electrons and holes in titanium oxide excited by light are efficiently separated, and the photocatalytic performance is improved. .

  Further, the catalyst efficiency can be improved by adding an adsorbing substance to titanium oxide. Examples of such adsorbents include adsorbents such as zeolite and activated carbon.

  These adsorbed substances can adsorb the substance to be decomposed and then efficiently decompose by catalytic action.

  Next, 2nd Embodiment of the photocatalyst module of this invention is described with reference to FIG. 15 and FIG.

  The photocatalyst module 20 shown in FIG. 15 is characterized in that the base material 21 is composed of a honeycomb structure member formed of a porous material.

  The fine structure of the base material 21 has the porous structure shown in FIG. 1 as in the first embodiment, and an optical fiber is disposed in the hole of the base material 21.

  The photocatalyst module 20 is excellent in mechanical strength, and can increase the flow rate of fluid per unit time while increasing the specific surface area of the substrate, thereby reducing pressure loss as much as possible.

  The pressure loss of the photocatalyst module in which the base material has a honeycomb structure and the photocatalyst module in which the base material is a metal mesh was investigated. The test conditions were such that a constant flow rate of air was passed through each photocatalyst module and the inlet pressure and outlet pressure were measured and evaluated.

  FIG. 16 shows a graph in which the pressure loss of each photocatalyst module is normalized with the pressure loss of the photocatalyst module having a honeycomb structure as the base material being taken as 1.

  As is apparent from the results shown in FIG. 16, the pressure loss of the photocatalyst module of the metal mesh substrate is 1.5 or more than the pressure loss of the photocatalyst module of the honeycomb structure substrate. That is, the pressure loss of the photocatalyst module using the honeycomb structure base material is suppressed to almost half as compared with the photocatalyst module of the metal mesh base material.

  That is, according to the photocatalyst module 20 in which the base material 21 has a honeycomb structure, it is possible to provide a photocatalyst module having a large specific surface area and reduced pressure loss.

1 is a structural diagram showing a first embodiment of a photocatalyst module according to the present invention. The graph which compares the catalyst performance of the photocatalyst module by the material of an optical fiber. The graph which shows the relationship between the light transmittance of an optical fiber, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the length of an optical fiber, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the diameter of an optical fiber, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the porosity of a base material, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the structure of a base material, and the catalyst performance of a photocatalyst module. The graph which compares the amount of corrosion of the base material by base material. The graph showing the relationship between the base material and the amount of corrosion. The graph which shows the relationship between the film thickness of a photocatalyst layer, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the particle size of a titanium oxide particle, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the particle size of a titanium oxide particle aggregate, and the catalyst performance of a photocatalyst module. The graph which shows the relationship between the material of an optical fiber, and the catalyst performance of a photocatalyst module. The graph which shows the relationship of the catalyst performance of a photocatalyst module at the time of adding a porous substance or a metal element to a photocatalyst layer. FIG. 3 is a structural diagram showing a second embodiment of a photocatalyst module according to the present invention. The graph which shows the relationship between the structure of a base material, and pressure loss.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Optical fiber 3 Photocatalyst layer 10 and 20 Photocatalyst module 21 Base material

Claims (13)

A photocatalyst module in which a photocatalyst layer made of a photocatalyst material is integrally formed on a surface of a base material, wherein the base material is formed of a porous material, and an optical fiber is provided in a hole thereof. The photocatalyst module according to claim 1, wherein the optical fiber has a light transmittance of 30% to 100% between both ends of the optical fiber. The photocatalyst module according to claim 1, wherein the optical fiber has a length in a range of 0.5 mm to 10 mm. The photocatalyst module according to claim 1, wherein the optical fiber is provided in a range of 1 μm to 500 μm in diameter. The photocatalyst module according to claim 1, wherein the base material is composed of a member having a three-dimensional sponge structure formed of a porous material. The photocatalyst module according to claim 1, wherein the base material is made of a material having a porosity of 10% to 70%. 2. The photocatalyst module according to claim 1, wherein the base material is composed of a member having a honeycomb structure formed of a porous material. The photocatalyst module according to claim 1, wherein the substrate is made of cordierite. The photocatalyst module according to claim 1, wherein the base material is made of a material mainly composed of alumina. 2. The photocatalyst module according to claim 1, wherein the photocatalyst layer has a thickness of 0.1 μm to 10 μm. The photocatalyst module according to claim 1, wherein the titanium oxide particles forming the photocatalyst layer have an average particle diameter of 10 nm to 100 nm. 2. The photocatalyst module according to claim 1, wherein the titanium oxide particles forming the photocatalyst layer are aggregated, and the average particle diameter of the titanium oxide particle aggregate is 10 nm to 200 nm. 2. The photocatalyst module according to claim 1, wherein the photocatalyst layer is formed of a photocatalyst material containing at least one selected from Au, Ag, Ru, Rh, Pd, Os, Ir, and Pt.

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