CN106794456B - Photocatalyst composition and method for producing same - Google Patents
Photocatalyst composition and method for producing same Download PDFInfo
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- CN106794456B CN106794456B CN201580045815.4A CN201580045815A CN106794456B CN 106794456 B CN106794456 B CN 106794456B CN 201580045815 A CN201580045815 A CN 201580045815A CN 106794456 B CN106794456 B CN 106794456B
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- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 1
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing arsenic, antimony, bismuth, vanadium, niobium tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
-
- B01J35/30—
-
- B01J35/51—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
Abstract
A photocatalyst composition which can sustain adsorption performance and decomposition performance is provided. The photocatalyst composition (1) of the present invention comprises: adsorbent particles (2) having light transmission properties; and photocatalyst particles (3), the adsorbent particles (2) and the photocatalyst particles (3) being present in a dispersed state.
Description
Technical Field
The present invention relates to a photocatalyst composition and a method for producing the same, and particularly relates to a solid photocatalyst composition in which adsorbent particles and photocatalyst particles are present in a dispersed state, and a method for producing the same.
Background
Conventionally, a method of improving the performance of decomposing Volatile Organic Compounds (VOC) and odorous substances by combining an adsorbent and a photocatalyst has been known.
For example, patent documents 1 and 2 disclose deodorizing agents or deodorizing filters each comprising a combination of zeolite and a photocatalyst.
Specifically, fig. 15 is a sectional view schematically showing the deodorant described in patent document 1. As shown in fig. 15, the deodorizing agent 101 disclosed in patent document 1 is configured such that the surface of zeolite particles 102 is covered with fine particles 103 of a visible-light-responsive photocatalyst. The deodorant 101 can have a sufficient gas removal rate and can stably remove gas even in a situation where ultraviolet rays are very little, such as indoors and in automobiles.
The deodorizing filter described in patent document 2 is configured such that a photocatalyst is supported on the surface of a porous compact containing a hydrophobic zeolite. The hydrophobic zeolite adsorbs malodorous components and hardly adsorbs moisture, so that the malodorous components can be trapped at a high concentration. In addition, the captured malodorous components are efficiently decomposed by the action of the photocatalyst supported on the surface of the hydrophobic zeolite. This enables regeneration of the adsorbent and continuous utilization of the adsorption force, and therefore, the deodorant effect is very excellent.
Documents of the prior art
Patent document
Patent document 1: japanese laid-open patent publication No. 2007-167699 (published on 7.5.2007) "
Patent document 2: japanese laid-open patent publication No. 2002-136811 (published 5/14/2002) "
Disclosure of Invention
Problems to be solved by the invention
However, the structures described in patent documents 1 and 2 have the following problems: the adsorption performance of the adsorbent is insufficient, and the decomposition performance of the photocatalyst cannot be sustained.
Specifically, in both of the configurations described in patent documents 1 and 2, a photocatalyst is supported on the surface of an adsorbent. Therefore, the loading of the photocatalyst with respect to the adsorbent is also limited to the maximum amount by which the entire surface of the adsorbent is covered with the layer of photocatalyst. However, the more the photocatalyst is supported, the less the amount of the surface of the adsorbent is exposed, and therefore the adsorbent is not exposed to the decomposition target. As a result, the adsorption performance of the adsorbent cannot be sufficiently exhibited.
Further, when used for a long period of time, the photocatalyst supported on the surface of the adsorbent peels off, and therefore the amount of the photocatalyst is insufficient. As a result, the decomposition performance of the photocatalyst may be deteriorated with time.
The present invention has been made in view of the above problems, and an object thereof is to provide a photocatalyst composition capable of sustaining adsorption performance and decomposition performance. Another object of the present invention is to provide a photocatalyst composition having both adsorption performance and decomposition performance.
Means for solving the problems
In order to solve the above problems, a photocatalyst composition according to an embodiment of the present invention is a solid photocatalyst composition containing: adsorbent particles having at least one of light transmittance and light reflectance; and photocatalyst particles, wherein the adsorbent particles and the photocatalyst particles are present in a dispersed state.
Effects of the invention
According to one embodiment of the present invention, the following effects are obtained: it is possible to provide a photocatalyst composition which can sustain the adsorption performance of the adsorbent and the decomposition performance of the photocatalyst. In addition, according to one embodiment of the present invention, the following effects are also obtained: a photocatalyst composition which can achieve both of the adsorption performance of an adsorbent and the decomposition performance of a photocatalyst can be provided.
Drawings
Fig. 1 is a schematic view schematically showing the appearance of a photocatalyst composition according to embodiment 1 of the present invention.
Fig. 2 is a schematic view showing an evaluation apparatus used for evaluating the gas adsorption/decomposition performance of the photocatalyst composition.
Fig. 3 is a graph showing the evaluation results of the gas adsorption/decomposition performance of the photocatalyst composition.
Fig. 4 is a diagram showing an SEM image obtained by imaging the photocatalyst composition.
Fig. 5 is a diagram showing an SEM image obtained by photographing a conventional photocatalyst composition as a comparative object.
Fig. 6 is a graph showing a comparison of gas adsorption performance of the photocatalyst composition and a conventional photocatalyst composition.
Fig. 7 is a graph showing gas decomposition performance of the photocatalyst composition and a conventional photocatalyst composition.
Fig. 8 is a sectional view schematically showing a photocatalyst composition of embodiment 2 of the present invention.
Fig. 9 is a sectional view schematically showing a photocatalyst composition of embodiment 3 of the present invention.
Fig. 10 is a sectional view schematically showing a photocatalyst composition of embodiment 4 of the present invention.
Fig. 11 is a perspective view schematically showing the appearance of the photocatalyst composition of embodiment 5 of the present invention.
Fig. 12 is a sectional view schematically showing a photocatalyst composition of embodiment 5 of the present invention.
Fig. 13 is a graph comparing gas adsorption performance per unit amount of adsorbent particles of the above-described photocatalyst composition and a conventional photocatalyst composition.
Fig. 14 is a graph comparing gas adsorption performance per unit photocatalyst particle amount of the above-described photocatalyst composition and a conventional photocatalyst composition.
Fig. 15 is a sectional view schematically showing the deodorant described in patent document 1.
Detailed Description
[ embodiment mode 1]
Hereinafter, embodiments of the present invention will be described in detail. The embodiment described below is an example of the present invention, and does not limit the contents of the present invention.
[ constitution of photocatalyst composition 1]
First, the structure of the photocatalyst composition of the present embodiment will be described with reference to fig. 1. Fig. 1 is a schematic view schematically showing the appearance of a photocatalyst composition 1 according to embodiment 1 of the present invention. As shown in fig. 1, the photocatalyst composition 1 of the present embodiment is in a solid state (solid state), and forms an aggregate in which the adsorbent particles 2 and the photocatalyst particles 3 are present in a dispersed state. Further, voids 6 are formed in the photocatalyst composition 1.
The adsorbent particles 2 can adsorb and/or decompose the decomposition object of the photocatalyst composition 1. The adsorbent particles 2 have at least one of light transmittance and light reflectance. Specifically, the adsorbent particles 2 have a property of transmitting or reflecting at least a part of light of a wavelength absorbed by the photocatalyst particles 3, or a property of transmitting and reflecting at least a part of light of a wavelength absorbed by the photocatalyst particles 3. For example, the sorbent particulates 2 can include zeolites, sepiolites, mesoporous silica, activated clays, or mixtures of a plurality (at least 2) of these materials.
Minerals such as zeolite and sepiolite, mesoporous silica, and activated clay have properties such that the longer the wavelength in the wavelength region from visible light to near ultraviolet, the lower the light absorption rate, and the higher the sum of the light transmittance and the light reflectance. The configuration of the zeolite is not particularly limited, and various configurations such as BEA, CHA, EMT, ERI, FAU, FER, GIS, HEU, LTA, LTL, MAZ, MEI, MEL, MFI, MOR, MTW, OFF, or MCM41, MCM48 can be used. In addition, natural zeolite or synthetic zeolite can be used.
The size (average particle diameter) of the adsorbent particles 2 is not particularly limited, and is generally, for example, about 0.1 μm or more and about 1 μm or less in diameter (in the case of spherical particles) or maximum length (in the case of non-spherical particles). The reason why the adsorbent particles 2 have at least one of the light transmittance and the light reflectance will be described later. Further, the size (average particle diameter) of the adsorbent particles 2 shows a value measured by an optical particle size distribution meter and observed by SEM/TEM.
The photocatalyst particles 3 can adsorb and/or decompose the decomposition object of the photocatalyst composition 1 by absorbing light. That is, the photocatalyst particles 3 exhibit photocatalytic activity by being irradiated with light having a wavelength with an energy of a band gap or more. The wavelength of light absorbed by the photocatalyst particles 3 is not particularly limited. For example, the photocatalyst particles 3 may be a visible-light-responsive photocatalyst that absorbs visible light to exhibit photocatalytic activity, an ultraviolet-light-responsive photocatalyst that absorbs ultraviolet light to exhibit photocatalytic activity, or a mixture of a visible-light-responsive photocatalyst and an ultraviolet-light-responsive photocatalyst. However, the photocatalyst particles 3 are preferably visible-light-responsive photocatalysts.
Preferred visible light-responsive photocatalysts are, for example, those comprising WO3、W25O73、W20O58、W24O68Or a mixture thereof. In addition, titanium dioxide (TiO) modified to function also in the visible light region by introducing a specific metal ion or nitrogen into an oxygen site may be used2) Used as visible light responsive photocatalyst. The visible light-responsive photocatalyst may also be a mixture of tungsten oxide and such modified titanium dioxide.
On the other hand, examples of the ultraviolet-responsive photocatalyst include titanium dioxide (TiO)2: also referred to simply as titanium oxide), and the like.
The size of the photocatalyst particles 3 is not particularly limited, but is preferably smaller than the adsorbent particles 2. This enables the photocatalyst particles 3 to be reliably dispersed in the photocatalyst composition 1. The size (average particle diameter) of the photocatalyst particles 3 is preferably, for example, about 1nm to 10nm in diameter (in the case of spherical particles) or in maximum length (in the case of non-spherical particles). The size (average particle diameter) of the photocatalyst particles 3 indicates a value measured by an optical particle size distribution meter and observed by SEM/TEM.
In the photocatalyst composition 1, the content (weight ratio) of the adsorbent particles 2 to the photocatalyst particles 3 is not particularly limited as long as it is set according to the use of the photocatalyst composition 1. When the effect of the adsorbent particles 2 is emphasized, the photocatalyst composition 1 containing more adsorbent particles 2 than photocatalyst particles 3 may be used. On the other hand, when the effect of the photocatalyst particles 3 is emphasized, the photocatalyst composition 1 containing more photocatalyst particles 3 than adsorbent particles 2 may be used. For example, the weight ratio of the adsorbent particles 2/photocatalyst particles 3 is preferably 1 to 9, more preferably 1.5 to 4. This provides the photocatalyst composition 1 in which the effect (adsorption performance) of the adsorbent particles 2 and the effect (decomposition performance) of the photocatalyst particles 3 are balanced.
The proportion of the voids 6 (void ratio) in the photocatalyst composition 1 can be arbitrarily set, but is preferably 30 to 50 vol% with respect to 100 vol% of the volume ratio of the photocatalyst composition 1, for example. Here, the porosity represents a proportion of the void 6 (space) in the apparent volume of the photocatalyst composition 1. Thus, even in the wavelength region where the adsorbent particles 2 have light reflectivity, light can reach the inside of the photocatalyst composition 1 as in the wavelength region having light transmissivity. In addition, the decomposition target substance permeates into the voids 6, and can be sufficiently adsorbed by the adsorbent particles 2 in the photocatalyst composition 1.
The form of the photocatalyst composition 1 is not particularly limited as long as it is a solid state. As shown in fig. 1, in the present embodiment, in the photocatalyst composition 1, the adsorbent particles 2 and the photocatalyst particles 3 include a bulk aggregate. The photocatalyst composition 1 may be in the form of powder, granule, pellet (pellet), honeycomb, film, or the like, and preferably in the form of pellet.
Further, the photocatalyst composition 1 may also include the adsorbent particles 2 and the photocatalyst particles 3, and may also contain other components. For example, various binders and the like may be contained.
[ method for producing photocatalyst composition 1]
Next, a method for producing the photocatalyst composition 1 will be described. The method for producing the photocatalyst composition 1 is not particularly limited, and for example, a production method including: a dispersion step of dispersing the adsorbent particles 2 and the photocatalyst particles 3 from the surface of the photocatalyst composition 1 toward the inside.
Specifically, in the dispersing step, the powdery adsorbent particles 2 and the powdery photocatalyst particles 3 are mixed, and an aggregate of these particles is fixed and molded into a block. That is, the method for producing the photocatalyst composition 1 includes: a mixing step of mixing the adsorbent particles 2 and the photocatalyst particles 3; and a forming step of forming the adsorbent particles 2 and the photocatalyst particles 3 mixed in the mixing step. This enables production of the photocatalyst composition 1.
Further, the voids 6 can be formed in the photocatalyst composition 1 depending on the conditions of the fixing and molding. For example, the photocatalyst composition 1 having the voids 6 formed therein can be produced by mixing the powdery adsorbent particles 2 and the powdery photocatalyst particles 3 at a certain ratio, fixing and molding an aggregate of these particles (fixing and molding the inside of the photocatalyst composition 1) into a block shape having voids, then mixing the powdery adsorbent particles 2 and the powdery photocatalyst particles 3 at another ratio around the mixture, and fixing and molding the mixture with voids (fixing and molding the surface of the photocatalyst composition 1) by the same or another molding method. In this production method, if the proportions of the powdery adsorbent particles 2 and the powdery photocatalyst particles 3 at the time of the fixing and molding are made the same, a photocatalyst composition having a uniform composition ratio of the adsorbent particles and the photocatalyst particles can be produced.
The method for forming the photocatalyst composition 1 is not particularly limited, and the granulation may be performed by a ring die method or a flat die method, or may be performed by a briquetting machine. Other granulation methods applicable to the production of the photocatalyst composition 1 include spray drying, extrusion granulation, rotary granulation, and thermoforming granulation.
In the case of producing the photocatalyst composition 1 by granulation, other components may be mixed in addition to the adsorbent particles 2 and the photocatalyst particles 3. Typical examples of other ingredients are binders. For example, the photocatalyst composition 1 may be produced by mixing and molding an organic or inorganic binder such as clay, CMC (carboxymethyl cellulose), or a resin as a binder together with the adsorbent particles 2 and the photocatalyst particles 3.
The photocatalyst composition 1 thus produced is preferably formed into a substantially spherical shape from the viewpoint of the permeability of the treatment and decomposition target. The particle diameter (diameter) when the molding is substantially spherical is not particularly limited, but is preferably, for example, about 0.5mm or more and 5mm or less. In other words, the photocatalyst composition 1 is preferably formed in the form of a pellet having a particle diameter (diameter) of about 0.5mm to 5 mm. If the particle size is less than 0.5mm, handling may be difficult, and if it exceeds 5mm, there may be a problem in permeability of the decomposition target.
[ Effect of photocatalyst composition 1]
Next, the action of the photocatalyst composition 1 will be described. As described above, the photocatalyst composition 1 contains the adsorbent particles 2 and the photocatalyst particles 3. Both the adsorbent particles 2 and the photocatalyst particles 3 can adsorb and/or decompose the decomposition object of the photocatalyst composition 1. The decomposition target substance may be in any state of gas or liquid. Examples of the decomposition target include volatile organic solvents (VOC) such as toluene, xylene, and acetaldehyde, and odorous substances such as acetic acid, hydrogen sulfide, and methyl mercaptan. The photocatalyst composition 1 has an effect of adsorbing or decomposing such a decomposition object to remove it, and is therefore suitable for use in applications such as deodorization and deodorization.
The sorbent particles 2 generally have the following characteristics: the adsorption rate was high, but once saturated, adsorption could not be continued. On the other hand, the photocatalyst particles 3 generally have the following characteristics: the decomposition rate is slow, but does not saturate and the decomposition continues. Therefore, if the adsorbent particles 2 and the photocatalyst particles 3 are combined, the decomposition target substance is rapidly adsorbed by the adsorbent particles 2, and the decomposition target substance adsorbed by the adsorbent particles 2 is decomposed by the photocatalyst particles 3. Thus, the adsorbent particles 2 are not saturated. On the other hand, the decomposition rate of the photocatalyst particles 3 depends on the concentration of the decomposition target. When the photocatalyst particles 3 decompose the decomposition target substance adsorbed at a high concentration to the adsorbent particles 2, the decomposition rate also increases. Therefore, the photocatalyst composition 1 can obtain a synergistic effect that the adsorbent particles 2 are not saturated and the decomposition rate of the photocatalyst particles 3 is high.
In the photocatalyst composition 1 of the present embodiment, the adsorbent particles 2 and the photocatalyst particles 3 are present in a dispersed state. Therefore, for example, by placing the photocatalyst composition 1 in a gas atmosphere to be removed, the gas to be removed can be adsorbed by the effect of the adsorbent particles 2, and then the photocatalyst particles 3 absorb light, whereby the gas to be removed can be decomposed by the effect of the photocatalyst particles 3.
In the photocatalyst composition 1, the photocatalyst particles 3 are dispersed and present not only on the outermost surface but also inside the photocatalyst composition 1. However, the adsorbent particles 2 have at least one of light transmittance and light reflectance. Therefore, in the case where the adsorbent particles 2 have light transmissivity, the light directly reaches the photocatalyst particles 3 inside. In addition, since the voids 6 are formed in the photocatalyst composition 1, light can reliably reach the photocatalyst particles 3 inside through the voids 6 both when the adsorbent particles 2 have light transmittance and when they have light reflectance. In particular, minerals such as zeolite and sepiolite have a lower light absorption rate and a higher sum of light transmittance and light reflectance as the wavelength is longer in the wavelength region from visible light to near ultraviolet. Therefore, if the adsorbent particles 2 are made of zeolite, sepiolite, or a mixture thereof having high light transmittance, sufficient light can be made to reach the photocatalyst particles 3 inside.
As described above, in the photocatalyst composition 1 of the present embodiment, the adsorbent particles 2 and the photocatalyst particles 3 having at least one of the light transmittance and the light reflectance are present in a dispersed state. This makes it possible to ensure a sufficient amount of photocatalyst particles 3 without impairing the adsorption ability of the adsorbent particles 2, and to facilitate handling. Therefore, the photocatalyst composition 1 can be provided which exhibits high gas adsorption/decomposition performance and is less likely to deteriorate in gas decomposition performance even when used for a long period of time. Thus, the photocatalyst composition 1 capable of sustaining the adsorption performance of the adsorbent particles 2 and the decomposition performance of the photocatalyst particles 3 can be provided. Further, the photocatalyst composition 1 can be provided which can achieve both the adsorption performance of the adsorbent particles 2 and the decomposition performance of the photocatalyst particles 3.
In addition, the photocatalyst composition 1 of the present embodiment has a void 6 formed therein. Thus, in the wavelength region where the adsorbent particles 2 have light reflectivity, light can be made to reach the inside of the photocatalyst composition 1 through the voids 6, as in the wavelength region having light transmissivity. The decomposition target substance penetrates the voids 6 and can be adsorbed by the adsorbent particles 2 in the photocatalyst composition 1. Further, by forming the voids 6 at a ratio of 30 vol% or more and 50 vol% or less with respect to 100 vol% of the photocatalyst composition 1, it is possible to more reliably allow light to reach the inside of the photocatalyst composition 1 and sufficiently adsorb the decomposition target substance to the adsorbent particles 2 in the inside of the photocatalyst composition 1.
[ evaluation of photocatalyst composition 1]
(preparation of photocatalyst composition 1 to be evaluated)
The photocatalyst adopts tungsten oxide, the adsorbent adopts ZSM-5 type zeolite, and the adhesive adopts CMC. And (3) reacting tungsten oxide: zeolite: the weight ratio of the adhesive is 1: 8.5: 0.5, extrusion granulation and rotary granulation were used in combination to produce the photocatalyst composition 1 in pellet form.
(production of photocatalyst compositions for comparison objects (comparative examples 1 and 2))
Comparative example 1 photocatalyst composition having photocatalyst supported on ceramic surface
Tungsten oxide is used as the photocatalyst, and a porous (sponge-like) ceramic filter is used as the ceramic. And (3) reacting tungsten oxide: the weight ratio of the ceramic filter is 1: and 9, preparing a photocatalyst composition with photocatalyst supported on the surface of the ceramic by impregnation.
Comparative example 2 photocatalyst composition having photocatalyst supported on surface of zeolite
In addition, although the configuration of the zeolite used in comparative example 2 was different from that of the zeolite used in the evaluation target, it was confirmed that the photocatalyst composition having the photocatalyst supported on the zeolite surface had the same ability when the powder of each zeolite was evaluated as a monomer (gas adsorption rate 1.6[ h-1 ]).
(evaluation method)
Fig. 2 is a schematic view showing a measurement system (evaluation apparatus 10) for evaluating the gas adsorption/decomposition performance of the photocatalyst composition 1. As shown in fig. 2, the evaluation apparatus 10 includes a light shielding box 11, a light source 12, a gas bag 13, and a culture dish 14. The light source 12 is provided in a direction from the center of the ceiling inside the light shielding box 11 toward the ground. The gas bag 13 is provided at the center of the ground of the light shielding box 11, and the culture dish 14 is housed inside the gas bag 13. The light-shielding box 11 is configured to prevent light from passing between the inside and the outside of the light-shielding box 11, and light other than light emitted from the light source 12 is not irradiated to the gas bag 13. The light source 12 was illuminated with a blue LED at a wavelength of 450nm at a irradiance of about 7mW/cm 2. The gas bag 13 has a capacity of 5L, is transparent at a wavelength of 450nm or so, and is hermetically sealed so that gas cannot enter and exit. The petri dish 14 is made of quartz glass, and an object (photocatalyst composition 1) to be measured for the gas adsorption/decomposition rate is placed therein.
Acetaldehyde gas is used as a representative gas of VOC and gases causing various odors as a gas to be decomposed. The time dependence of the change in the gas concentration was measured, and the magnitude of the slope [ h-1] was defined as the gas adsorption/decomposition rate when the ordinate represents the logarithm of the gas concentration and the abscissa represents time. The time dependence of the change in concentration due to adsorption and decomposition of the gas is linear in the logarithm, and therefore, the slope is not affected by any initial concentration, but the initial concentration of the gas is measured at about 500 ppm. That is, 500ppm of acetaldehyde gas was sealed in the gas bag 13 together with the petri dish 14 on which the object to be measured (photocatalyst composition 1) was placed, and the light was irradiated from the light source 12 to measure the time dependence of the change in the gas concentration. The gas concentration was measured using acetaldehyde detection tube No.92 manufactured by gas technology (ガステック).
At this time, only the gas adsorption rate according to the effect of the adsorbent particles 2 may be measured without irradiating light from the light source 12.
(evaluation results)
The gas adsorption/decomposition rate of the photocatalyst composition 1 to be evaluated was measured by the above-described evaluation method. Fig. 3 is a graph showing the results of evaluation of the gas adsorption/decomposition performance of the photocatalyst composition 1. The graph of fig. 3 also shows the measurement results of the photocatalyst composition (comparative example 1) in which photocatalyst particles are supported on the surface of the ceramic as a comparative object.
As shown in fig. 3, in the comparative example (ceramic + photocatalyst (surface-supported)), since the adsorbent particles 2 were not present, adsorption decomposition of the gas was hardly observed if light irradiation was not performed. However, the effect of the photocatalyst particles was exhibited by the light irradiation, and the gas adsorption/decomposition rate was measured to be 0.8[ h-1 ].
On the other hand, in the photocatalyst composition 1 (zeolite + photocatalyst mixed pellet) to be evaluated, the adsorption rate of gas was 1.5[ h-1] when no light irradiation was performed, and the gas decomposition rate was increased to 2.8[ h-1] when light irradiation was performed.
From this fact, it is understood that in the photocatalyst composition 1 of the present embodiment, the effects of the adsorbent particles 2 and the effects of the photocatalyst particles 3 are not simply added, and a higher gas adsorption/decomposition performance is exhibited by a synergistic effect.
Next, the results of comparison between the photocatalyst composition 1 of the present embodiment and a conventional photocatalyst composition (a photocatalyst composition in which photocatalyst particles are supported on the surfaces of adsorbent particles) to be compared will be described with reference to fig. 4 to 7. Fig. 4 is a diagram showing an SEM image obtained by photographing the photocatalyst composition 1. Fig. 5 is a diagram showing an SEM image obtained by photographing a conventional photocatalyst composition as a comparative object (comparative example 2).
Conventionally, as described in patent documents 1 and 2, a method of causing photocatalyst particles to be supported on the surfaces of adsorbent particles has been adopted as a means for exhibiting the combined effect of the adsorbent particles and the photocatalyst particles. The idea is that the photocatalyst particles must be irradiated with light to decompose the decomposition target such as gas, and the photocatalyst is disposed on the surface of the adsorbent particles to which light is easily irradiated.
In the photocatalyst composition 1 of the present embodiment, the photocatalyst particles 3 are dispersed and present not only on the surface of the photocatalyst composition 1 but also inside the photocatalyst composition 1.
As described above, the photocatalyst composition 1 to be evaluated and the photocatalyst composition to be compared (comparative example 2) both used zeolite as the adsorbent particles, and the photocatalyst particles 3 were formed at a ratio of about 10 to 20% by weight.
As shown in fig. 4, on the surface of the photocatalyst composition 1 to be evaluated, a large number of zeolite particles (adsorbent particles 2) having a particle diameter of about 0.5 μm were exposed, and photocatalyst particles 3 having a particle diameter of about 0.1 μm were found throughout.
On the other hand, as shown in fig. 5, it is understood that in the photocatalyst composition of comparative example 2, the surfaces of the zeolite (adsorbent particles) are substantially covered with the photocatalyst particles. In such a configuration, the photocatalyst particles are exposed on the surface, and the zeolite is not exposed on the surface, and therefore the gas adsorption performance cannot be sufficiently exhibited.
Next, the measurement results of the actual gas adsorption performance of the photocatalyst composition 1 and the conventional photocatalyst composition will be described based on fig. 6. Fig. 6 is a graph comparing gas adsorption performance of the photocatalyst composition 1 and a conventional photocatalyst composition (comparative example 2). Fig. 6 also shows, as a comparison, the measurement results of the gas adsorption rate of the zeolite-only pellet not supporting the photocatalyst particles.
As shown in fig. 6, the gas adsorption rate of the photocatalyst composition 1 (zeolite + photocatalyst mixed pellet) to be evaluated was approximately 1.5[ h-1] as compared with that of the pellet of zeolite alone.
On the other hand, the gas adsorption rate of the photocatalyst composition (zeolite pellet + photocatalyst (surface-supported)) of comparative example 2 was 1.2[ h-1], and it was found that the gas adsorption performance was lower than that of the photocatalyst composition 1 to be evaluated and the zeolite alone.
Considering the results of the SEM image of fig. 5 and the results of fig. 6, it is conceivable that the photocatalyst particles 3 negatively affect the gas adsorption performance of the adsorbent particles 2 because the zeolite surface is covered with the photocatalyst particles.
Next, the measurement results of the actual gas adsorption performance of the photocatalyst composition 1 and the conventional photocatalyst composition will be described based on fig. 7. Fig. 7 is a graph comparing gas decomposition performance of the photocatalyst composition 1 and a conventional photocatalyst composition (comparative example 2).
As shown in FIG. 7, the gas decomposition rates were all 2.8[ h-1 ]. This result shows that even in a configuration in which the photocatalyst particles 3 are present inside the pellet like the photocatalyst composition 1, by using the light-transmissive adsorbent particles 2 and the visible-light-responsive photocatalyst particles 3, light can sufficiently reach the inside photocatalyst particles 3. Therefore, it was confirmed that the photocatalyst composition 1 had gas decomposition performance at the same level as that of the photocatalyst composition of comparative example 2 (zeolite pellet + photocatalyst (surface supporting)) in which photocatalyst particles were supported on the surfaces of adsorbent particles.
On the other hand, in the photocatalyst composition of comparative example 2, since the photocatalyst particles are supported on the surface of the zeolite shot, if chips or the like fall off from the shot in the unlikely event of long-term use, the photocatalyst particles existing on the surface are preferentially exfoliated. As a result, the gas decomposition performance is degraded, and finally, the pellets are formed only of the adsorbent particles.
On the other hand, in the photocatalyst composition 1, the photocatalyst particles 3 are present up to the inside, and therefore, even if used for a long period of time, the gas decomposition performance can be continued without completely disappearing. Therefore, the photocatalyst composition 1 having a long life can be realized.
Further, in the photocatalyst composition 1, the ratio (composition ratio) of the adsorbent particles 2 to the photocatalyst particles 3 is uniform at each position inside thereof. Thus, even if the chipping falls off, the ratio of the adsorbent particles 2 to the photocatalyst particles 3 is fixed. Therefore, in the photocatalyst composition 1, the optimum balance of adsorption and decomposition can always be maintained. In addition, in the case where the adsorbent particles 2 and the photocatalyst particles 3 are extremely consumed, the same photocatalyst composition 1 is additionally supplemented, whereby the gas adsorption/decomposition performance can be restored while maintaining the balance between adsorption and decomposition.
As described above, in the photocatalyst composition 1, the adsorbent particles 2 and the photocatalyst particles 3 are present in a dispersed state, and therefore, the adsorption performance and the decomposition performance can be continued.
[ embodiment 2]
Another embodiment of the present invention is described below with reference to fig. 8. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and explanations thereof are omitted.
Fig. 8 is a sectional view schematically showing a photocatalyst composition 1a of embodiment 2 of the present invention. As shown in fig. 8, the photocatalyst composition 1a of the present embodiment is in the form of a substantially spherical pellet. In addition, although not shown, in the photocatalyst composition 1a, the adsorbent particles 2 and the photocatalyst particles 3 are present in a dispersed state. The inside of the photocatalyst composition 1a has a two-layer structure of an outer layer (surface layer) 4a and an inner layer 5 a. In the photocatalyst composition 1a, the proportion of the adsorbent particles 2 is higher in the outer layer 4a than the proportion of the photocatalyst particles 3, and the proportion of the photocatalyst particles 3 is higher in the inner layer 5a than the proportion of the adsorbent particles 2. That is, in the photocatalyst composition 1a, the presence ratio of the adsorbent particles 2 and the photocatalyst particles 3 in the outer layer 4a and the inner layer 5a is not uniform. The photocatalyst composition 1a has a two-layer structure, but may have a multilayer structure of three or more layers.
According to the photocatalyst composition 1a, the content of the adsorbent particles 2 in the outer layer 4a which is more likely to contact the decomposition target is high. Thereby, the following functions can be realized: the decomposition target substance is rapidly adsorbed by the adsorbent particles 2 existing in the outer layer 4a in a larger amount, and is finely decomposed by the photocatalyst particles 3 in the inner layer 5a having a high content of the photocatalyst particles 3 in a larger amount.
In addition, in the photocatalyst composition 1a, since the adsorbent particles 2 are consumed from the outside where the proportion is large in the long term, a pellet of the photocatalyst composition 1a in which adsorption is emphasized in the short term and decomposition is emphasized in the long term can be realized.
The method for producing the photocatalyst composition 1a having such a two-layer structure can be thought of, for example, as follows: the inner layer 5a is formed by pressing, and molding using a ring mold or a flat mold, and then the outer layer 4a is formed again by changing the material ratio. The production method is not limited to these, and two or more layers of the photocatalyst composition 1a having a multilayer structure may be produced by sequentially molding from the inner layer 5 a.
[ embodiment 3 ]
Another embodiment of the present invention is described below with reference to fig. 9. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and explanations thereof are omitted.
Fig. 9 is a sectional view schematically showing a photocatalyst composition 1b of embodiment 3 of the present invention. The photocatalyst composition 1b of fig. 9 is obtained by reversing the ratio of the adsorbent particles 2 to the photocatalyst particles 3 in the outer layer 4a and the inner layer 5a of the photocatalyst composition 1a of fig. 8. That is, the inside of the photocatalyst composition 1b is also a two-layer structure of the outer layer 4b and the inner layer 5 b. In the photocatalyst composition 1b, the proportion of the photocatalyst particles 3 is higher in the outer layer 4a than in the proportion of the adsorbent particles 2, and the proportion of the adsorbent particles 2 is higher in the inner layer 5a than in the proportion of the photocatalyst particles 3. The photocatalyst composition 1b has a two-layer structure, but may have a multilayer structure of three or more layers.
According to the photocatalyst composition 1b, the function opposite to that of the photocatalyst composition 1a can be realized. That is, according to the photocatalyst composition 1b, pellets of the photocatalyst composition 1b in which decomposition is regarded as important in the short term and adsorption is regarded as important in the long term can be realized. The method for producing the photocatalyst composition 1b is the same as that of the photocatalyst composition 1a, and therefore, the description thereof is omitted.
[ embodiment 4 ]
Another embodiment of the present invention is described below with reference to fig. 10. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and explanations thereof are omitted.
Fig. 10 is a sectional view schematically showing a photocatalyst composition 1c of embodiment 4 of the present invention. The photocatalyst composition 1c of fig. 10 is formed by forming the inner layer 5a of the photocatalyst composition 1a of fig. 8 into a multilayer structure. That is, the photocatalyst composition 1c comprises an outer layer (surface layer) 4c and an inner layer 5c, and the inner layer 5c comprises 12 layers 51 to 62.
Further, in the photocatalyst composition 1c, the ratio (composition ratio) of the adsorbent particles 2 to the photocatalyst particles 3 continuously changes from the outer layer 4c toward the inside. That is, in the photocatalyst composition 1c, the presence ratio of the adsorbent particles 2 and the photocatalyst particles 3 is not uniform in the outer layer 4c and the inner layer 5c (layers 51 to 62). In the example of fig. 10, the lower the proportion of the adsorbent particles 2 and the higher the proportion of the photocatalyst particles 3 toward the center of the photocatalyst composition 1 c. However, it is also possible to reverse the method in which the proportion of the adsorbent particles 2 is higher and the proportion of the photocatalyst particles 3 is lower toward the center of the photocatalyst composition 1 c.
The photocatalyst composition 1c has the same configuration as the photocatalyst composition 1a, and therefore exhibits the same effects as the photocatalyst composition 1 b.
In addition, in the photocatalyst compositions 1a, 1b of embodiments 2, 3, the composition ratio of the adsorbent particles 2 and the photocatalyst particles 3 between the outer layers 4a, 4b and the inner layers 5a, 5b changes rapidly, and thus cracking, peeling, or the like may occur during granulation.
In the photocatalyst composition 1c of the present embodiment, the composition ratio of the adsorbent particles 2 to the photocatalyst particles 3 is continuously changed between the outer layer 4c and the inner layer 5c, and therefore, the occurrence of cracks, separation, and the like can be reduced during granulation.
The photocatalyst composition 1c can be produced by, for example, the following granulation method: in a granulation method in which pellets are sequentially grown from the inner layer 5c (innermost layer 62) as in the rotary granulation, the composition ratio of the charged material is changed according to the growth. The production method is not limited to this, and the ratio of the adsorbent particles 2 to the photocatalyst particles 3 can be freely controlled in accordance with the distance from the outer layer 4c (surface) by using a granulation method in which growth is started from the inner layer 5c (innermost layer 62).
[ embodiment 5 ]
Another embodiment of the present invention is described below with reference to fig. 11 and 12. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and explanations thereof are omitted.
Fig. 11 is a perspective view schematically showing the appearance of a photocatalyst composition 1d according to embodiment 5 of the present invention. Fig. 12 is a sectional view schematically showing a photocatalyst composition 1d of embodiment 5 of the present invention. As shown in fig. 11 and 12, the photocatalyst composition 1d of the present embodiment is solid (solid) like the photocatalyst composition 1 of embodiment 1, and forms an aggregate in which the adsorbent particles 2 and the photocatalyst particles 3 are present in a dispersed state. Further, as shown in fig. 12, a void 6 is also formed in the photocatalyst composition 1 d.
The photocatalyst composition 1d is different from the photocatalyst composition 1 in that the distribution density of the photocatalyst particles 3 on the surface of the photocatalyst composition 1d is the highest. Although the distribution density of the photocatalyst particles 3 in the photocatalyst composition 1d is not particularly limited, decomposition is more important when the distribution density is high, and adsorption is more important when the distribution density is low. That is, the higher the distribution density of the photocatalyst particles 3 is, the more important the photocatalyst composition 1d is to put the effect (decomposition performance) of the photocatalyst particles 3 on.
Specifically, as shown in fig. 12, in the photocatalyst composition 1d, the distribution density of the photocatalyst particles 3 is dense on the surface of the photocatalyst composition 1 and sparse in the inside. In other words, when the photocatalyst composition 1d is irradiated with parallel light from a certain direction, if the area ratio of the photocatalyst particles 3 directly irradiated with the parallel light to the adsorbent particles 2 is "a" and the volume ratio of the photocatalyst particles 3 not directly irradiated with the parallel light to the adsorbent particles 2 is "B" without considering the reflected light of the adsorbent particles 2, 1/a ≠ 0, B ≠ 0, and a > B in the photocatalyst composition 1.
The above "a" can be expressed by the area occupied by the surface of the photocatalyst particles 3 on the appearance of the photocatalyst composition 1 d/the area occupied by the surface of the adsorbent particles 2 on the appearance of the photocatalyst composition 1 d. The above "B" can be expressed by the volume occupied by the photocatalyst particles 3 in the photocatalyst composition 1 d/the volume occupied by the adsorbent particles 2 in the photocatalyst composition 1 d. The apparent surface area of the photocatalyst composition 1d in the above-mentioned "a" can be calculated from a photograph taken with an electron microscope or the like, for example. The volumes in "B" can be directly calculated by observation of the cross section and X-ray fluoroscopy, or the volume ratio can be calculated by calculating the weight ratio from the density and the porosity of the photocatalyst composition 1d, the density of the photocatalyst particles 3, and the density of the adsorbent particles 2.
The distribution density of the photocatalyst particles 3 may be the maximum at the surface of the photocatalyst composition 1d, and may be gradually decreased toward the inside.
In the photocatalyst composition 1d, the photocatalyst particles 3 exert their effects by receiving light, and therefore the more the photocatalyst particles exist on the surface of the photocatalyst composition 1d which receives strong light, the more efficiently. Therefore, the distribution density of the photocatalyst particles 3 is preferably the highest on the surface of the photocatalyst composition 1 d. Namely, A > B is preferable. On the other hand, the adsorbent particles 2 do not exhibit the adsorption performance unless they are brought into contact with the decomposition target, and therefore 1/a ≠ 0 is preferable. In addition, even inside the photocatalyst composition 1d, the reflected light and the transmitted light of the adsorbent particles 2 reach, and the light directly reaches the inside photocatalyst particles 3 through the voids 6. Accordingly, since the photocatalyst particles 3 in the inside also exert their effects, B ≠ 0 is preferable.
[ method for producing photocatalyst composition 1d ]
Next, a method for producing the photocatalyst composition 1d will be described. The method for producing the photocatalyst composition 1d is not particularly limited, and the following production methods are conceivable, for example.
For example, it can be produced by: the powdery adsorbent particles 2 and the powdery photocatalyst particles 3 are mixed at a certain ratio (1 st mixing step), and are fixed and molded into a block with voids as an aggregate of these particles (fixed molding inside the photocatalyst composition 1 d) (1 st molding step), and then the powdery adsorbent particles 2 and the powdery photocatalyst particles 3 are mixed around the mixture at a ratio that the photocatalyst particles 3 are larger than in the initial molding step (2 nd mixing step), and both are fixed and molded with voids by the same molding method as in the 1 st molding step or another molding method (fixed molding of the surface of the photocatalyst composition 1 d) (2 nd molding step). The molding methods in the 1 st molding step and the 2 nd molding step are the same as those described in embodiment 1.
In addition, the photocatalyst composition 1d can also be produced by: after the mixing step and the molding step of embodiment 1, a supporting step of supporting the photocatalyst particles 3 on the surface of the molded article obtained in the molding step is further performed.
According to this production method, the photocatalyst composition 1d can be easily produced.
Further, since the void 6 is formed when the photocatalyst composition 1d of the present embodiment is produced, in the production method in [ evaluation of the photocatalyst composition 1d ] described later, the photocatalyst particles 3 can be impregnated into the inside of the pellet in the process of impregnating the photocatalyst particles 3 into the pellet including the adsorbent particles 2 and the binder.
[ Effect of photocatalyst composition 1d ]
As described above, in the photocatalyst composition 1d of the present embodiment, the photocatalyst particles 3 are dispersed and present not only on the outermost surface but also inside the photocatalyst composition 1. The distribution density of the photocatalyst particles is highest on the surface of the photocatalyst composition 1 d. That is, the distribution density of the photocatalyst particles 3 is dense on the surface of the photocatalyst composition 1d and sparse in the inside. Therefore, in addition to the effect of the photocatalyst composition 1 of embodiment 1, the decomposition performance can be improved by strongly receiving light to a large number of photocatalyst particles 3.
In addition, since the voids 6 are formed in the photocatalyst composition 1d, a sufficient amount of the photocatalyst particles 3 can be secured without inhibiting the adsorption ability of the adsorbent particles 2.
[ evaluation of photocatalyst composition 1d ]
(preparation of photocatalyst composition 1d to be evaluated)
The photocatalyst adopts tungsten oxide, the adsorbent adopts ZSM-5 type zeolite, and the adhesive adopts polyethylene. And (3) reacting tungsten oxide: zeolite: the weight ratio of the adhesive is 0.5: 4.5: 5, forming the pellet in a pellet form with voids by thermoforming, and then loading the photocatalyst around the pellet by immersion to finally produce tungsten oxide around (on the surface of): internal tungsten oxide: zeolite: the weight ratio of the adhesive is 1.7: 0.5: 4.5: 5 in the form of pellets, and 1 d.
Further, from the optical surface observation, it was calculated that the "photocatalyst area/adsorbent area ratio (a)" of the surface of the photocatalyst composition 1d was about 100. Further, from the calculation of the respective densities of the photocatalyst and the adsorbent, it was calculated that the photocatalyst volume/adsorbent volume ratio B in the inside of the photocatalyst composition 1d was about 0.03, and the void ratio of the photocatalyst composition 1d was about 37%.
(production of photocatalyst composition for comparison (comparative example 3))
The photocatalyst adopts tungsten oxide, the adsorbent adopts ZSM-5 type zeolite, and the adhesive adopts polyethylene. And (3) reacting tungsten oxide: zeolite: the weight ratio of the adhesive is 2.5: 2.5: 5, the photocatalyst composition in pellet form was produced by thermoforming.
Further, from the optical surface observation, the degree of 0.005 was estimated as the photocatalyst area/adsorbent area ratio a, and from the calculation of the density, the degree of 0.03 was estimated as the photocatalyst volume/adsorbent volume ratio B. The porosity of the photocatalyst composition of comparative example 3 was calculated to be about 37%.
(evaluation method)
The photocatalyst compositions 1d of examples and the photocatalyst compositions of comparative examples were evaluated using the evaluation apparatus shown in fig. 2 in the same manner as in the evaluation method of embodiment 1.
Acetaldehyde gas is used as a representative gas of VOC and gases causing various odors as a gas to be decomposed. First, the change in gas concentration when acetaldehyde gas was adsorbed without irradiating the photocatalyst compositions of examples and comparative example 3 with light was measured, and the amount of gas decrease at the time when the change in gas concentration was no longer observed was divided by the amount of adsorbent to obtain the limit adsorption amount per unit amount of adsorbent. Next, the photocatalyst compositions of examples and comparative examples were irradiated with light to decompose acetaldehyde gas. The amount of decomposition of the gas was calculated by measuring the change in the carbon dioxide concentration resulting from the decomposition of acetaldehyde gas, and the result of dividing the slope of the change in the amount of decomposition by the amount of the photocatalyst was taken as the average decomposition rate per unit amount of the photocatalyst. The acetaldehyde gas concentration was measured using acetaldehyde detector tube No.92 and carbon dioxide detector tube No.2LC manufactured by gas technology.
(evaluation results)
The limiting adsorption amount and the average decomposition rate of the photocatalyst composition 1d of the present embodiment were measured by the above evaluation methods. Fig. 13 is a graph showing the evaluation results of the limit adsorption amount of the photocatalyst composition 1 d. The graph of fig. 13 also shows the measurement results of the photocatalyst composition (comparative example 3) having no photocatalyst particles supported on the surface thereof as a comparative object.
As shown in fig. 13, the photocatalyst composition 1d of the present embodiment and comparative example 3 had the same ultimate adsorption amount, or the photocatalyst composition 1d of the present embodiment was slightly superior. This is presumably because, unlike the conventional examples described in patent documents 1 and 2, the photocatalyst composition 1d of the present embodiment does not cover the entire surface of the photocatalyst composition 1 with the photocatalyst particles 3, but exposes the adsorbent particles 2 on the surface and has voids in the interior, so that gas can permeate therethrough and sufficiently adsorb the gas.
Next, the measurement results of the average decomposition rate in the photocatalyst composition 1d and comparative example 3 will be described based on fig. 14. Fig. 14 is a graph comparing the gas decomposition performance of the photocatalyst composition 1d and that of comparative example 3.
As shown in fig. 14, the average decomposition rate was 21.8[ ppm @ 5L/h ] in comparative example 3 and 26.3[ ppm @ 5L/h ] in photocatalyst composition 1 d. This result shows that even in the configuration in which the photocatalyst particles are present inside the pellet as in comparative example 3, by molding the photocatalyst particles with the voids 6 using the adsorbent particles 2 having light transmittance and light reflectance and the visible-light-responsive photocatalyst particles 3 as in the photocatalyst composition 1d, the light can sufficiently reach the photocatalyst particles 3 inside to decompose the gas. In the photocatalyst composition 1d, the photocatalyst particles 3 supported on the surface receive light directly, and therefore decomposition efficiency is high. Therefore, it was found that the photocatalyst composition 1d of the present embodiment has a higher gas decomposition efficiency of the photocatalyst particles 3 as compared with comparative example 3 as a whole. Therefore, it was confirmed that the photocatalyst composition 1d had a higher average decomposition rate and was superior in gas decomposition efficiency to comparative example 3 in which the photocatalyst particles were not additionally supported on the surface.
As described above, in the photocatalyst composition 1d, the distribution of the photocatalyst particles 3 is dense on the surface and sparse in the interior. This can maintain both the adsorption performance of the adsorbent and the decomposition performance of the photocatalyst, and can also enhance the decomposition performance by allowing the plurality of photocatalyst particles 3 to receive light strongly.
[ embodiment 6 ]
Another embodiment of the present invention is explained as follows. In this embodiment, a method for producing the photocatalyst composition 1d of embodiment 5 will be described. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and explanations thereof are omitted.
In the method for producing the photocatalyst composition 1d of the present embodiment, the dispersion step of dispersing the adsorbent particles 2 and the photocatalyst particles 3 from the surface of the photocatalyst composition 1d toward the inside thereof includes: a molding step of forming a molded article using the adsorbent particles 2 and a thermoplastic binder, the molded article having voids 6 formed therein; and a supporting step of supporting the photocatalyst particles 3 on the surface of the molded article having the above-described voids 6 formed therein.
For example, in the above-described molding step, the adsorbent particles 2 in powder form are fixed and molded into a block shape with the voids 6 by using a thermoplastic resin (thermoplastic adhesive) as a binder. Then, after the molding step, the above-described supporting step is performed, whereby the photocatalyst particles 3 are supported on the surface of the molded article obtained by the molding step by an impregnation method. This enables the photocatalyst composition 1d to be produced easily.
Examples of the thermoplastic adhesive used in the molding step include thermoplastic resins such as polypropylene and polyethylene. The molding method in the molding step is not particularly limited as long as it is a heating molding method. For example, the molding method may be: granulation by thermoforming is performed by flowing the mixed pellet of the adsorbent pellet 2 and the thermoplastic binder into a mold and heating the same to mold the same.
On the other hand, the method for impregnating the photocatalyst particles 3 in the supporting step may be, for example, the following method: the photocatalyst particles 3 are dispersed in a solvent such as water or alcohol, and impregnated into the molded article obtained in the molding step (block-shaped fixed molded article with the voids 6), and dried by heating or at room temperature.
According to this method, in the supporting step, the dispersion liquid of the photocatalyst particles 3 penetrates not only the surface of the fixed molded article obtained in the molding step but also the voids 6 to some extent. Therefore, the photocatalyst particles 3 can be supported to some extent in the inside of the fixed molded article. As a result, the photocatalyst particles 3 can be reliably dispersed in the photocatalyst composition 1d, and the photocatalyst particles 3 can be supported on the inside adsorbent particles 2.
In the manufacturing method of the present embodiment, it is preferable that the method further includes, after the loading step: and a fixing step of heating to soften the thermoplastic adhesive and then curing the softened thermoplastic adhesive to fix the photocatalyst particles 3 to the thermoplastic adhesive.
In this way, when the fixing step is performed after the loading step of loading the photocatalyst particles 3 by the impregnation method, the thermoplastic binder is softened in the fixing step and cooled to room temperature. This makes it possible to fix the photocatalyst particles 3 to the thermoplastic adhesive when the thermoplastic adhesive is cured again. As a result, the photocatalyst particles 3 can be supported on the thermoplastic binder in the photocatalyst composition 1 d. Therefore, the photocatalyst particles 3 can be reliably supported inside the photocatalyst composition 1 d.
[ embodiment 7 ]
Another embodiment of the present invention is explained as follows. In this embodiment, another method for producing the photocatalyst composition 1d of embodiment 5 will be described. For convenience of explanation, members having the same functions as those described in the above embodiments are given the same reference numerals, and explanations thereof are omitted.
In the method for producing the photocatalyst composition 1d of the present embodiment, the dispersion step of dispersing the adsorbent particles 2 and the photocatalyst particles 3 from the surface of the photocatalyst composition 1d toward the inside thereof includes: a molding step of forming a molded product using the adsorbent particles 2 and a thermosetting binder, the molded product having voids 6 formed therein; and a supporting step of supporting the photocatalyst particles 3 on the surface of the molded article having the above-described voids 6 formed therein.
For example, in the molding step, the powdery adsorbent particles 2 are heat molded using a thermosetting adhesive that is a binder and is cured under a plurality of conditions. For example, 2-stage thermosetting adhesives that are thermally cured under 2 different conditions are used as the adhesive. In the molding step, the block with the voids 6 is fixed and formed by the 1 st stage of curing. Then, the above-mentioned supporting step is performed after the molding step, whereby the photocatalyst particles 3 are supported on the surface of the molded article obtained by the molding step by an impregnation method. This enables the photocatalyst composition 1d to be produced easily.
The thermosetting adhesive used in the molding step is preferably a thermosetting adhesive cured under a plurality of conditions. For example, a thermosetting adhesive having such properties includes a 2-stage thermosetting resin which is thermally cured under 2 different conditions, and more specifically, a silicone-based resin or an epoxy-based resin.
The molding method in the molding step is not particularly limited as long as it is a molding method by heating. For example, the molding method may be: the granulation by the thermoforming is performed by flowing the mixed pellet of the adsorbent pellet 2 and the thermosetting binder into a mold and heating the same to mold the same.
On the other hand, the method for impregnating the photocatalyst particles 3 in the supporting step may be, for example, the following method: the photocatalyst particles 3 are dispersed in a solvent such as water or alcohol, and impregnated into the molded article obtained in the molding step (block-shaped fixed molded article with the voids 6), and dried by heating or at room temperature.
According to this method, in the supporting step, the dispersion liquid of the photocatalyst particles 3 penetrates not only the surface of the fixed molded article obtained in the molding step but also the voids 6 to some extent. Therefore, the photocatalyst particles 3 can be supported to some extent in the inside of the fixed molded article. As a result, the photocatalyst particles 3 can be reliably dispersed in the photocatalyst composition 1d, and the photocatalyst particles 3 can be supported on the inside adsorbent particles 2.
In the production method of the present embodiment, it is preferable that the method further includes, after the loading step: and a fixing step of fixing the photocatalyst particles 3 to the thermosetting adhesive by curing the thermosetting adhesive under a curing condition different from that in the molding step.
In this way, when the fixing step is performed after the loading step of loading the photocatalyst particles 3 by the dipping method, the 2 nd stage of curing occurs in the fixing step, and the photocatalyst particles 3 can be fixed to the thermosetting adhesive. As a result, the photocatalyst particles 3 can be supported on the thermoplastic binder inside the photocatalyst composition 1 d. Therefore, the photocatalyst particles 3 can be reliably supported inside the photocatalyst composition 1 d.
[ conclusion ]
The photocatalyst compositions 1, 1a, 1b, 1c, and 1d according to embodiment 1 of the present invention are solid photocatalyst compositions 1, 1a, 1b, and 1c, and contain: adsorbent particles 2 having at least one of light transmittance and light reflectance; and photocatalyst particles 3, wherein the adsorbent particles 2 and the photocatalyst particles 3 are present in a dispersed state.
According to the above constitution, the adsorbent particles and the photocatalyst particles are present in a dispersed state. That is, the photocatalyst particles are not present only on the surface of the adsorbent particles as in the techniques described in patent documents 1 and 2, but are also present in a dispersed state in the inside of the photocatalyst composition. This prevents the photocatalyst particles from inhibiting the adsorption of the decomposition target substance onto the adsorbent particles, and therefore, the photocatalyst particles can exhibit high adsorption performance.
Further, according to the above configuration, the photocatalyst particles are not supported (coated) on the surface of the adsorbent particles, and therefore, more photocatalyst particles can be contained than in this case. In addition, the problem of peeling of the photocatalyst particles from the surface of the adsorbent particles does not occur. Further, since the adsorbent particles have light transmittance, light also sufficiently reaches the photocatalyst particles existing inside. This can maintain the decomposition performance of the photocatalyst.
Therefore, a photocatalyst composition capable of sustaining the adsorption performance and the decomposition performance can be provided. Further, a photocatalyst composition having both of the adsorption performance and the decomposition performance can be provided.
In the photocatalyst compositions 1, 1a, 1b, 1c, and 1d according to embodiment 2 of the present invention, voids are preferably formed in embodiment 1. In the photocatalyst composition 1, 1a, 1b, 1c, 1d of embodiment 3 of the present invention, it is preferable that in embodiment 2, the proportion of the voids is 30 to 50% by volume based on 100% by volume of the photocatalyst composition.
According to the above configuration, in the wavelength region where the adsorbent particles 2 have light reflectivity, light reaches the inside of the photocatalyst composition through the voids. That is, in the wavelength region where the adsorbent particles have light reflectivity, light can reach the inside of the photocatalyst composition in the same manner as in the wavelength region where the adsorbent particles have light transmissivity. In addition, the gas penetrates the voids, and is sufficiently adsorbed by the adsorbent particles in the photocatalyst composition.
In the photocatalyst compositions 1, 1a, 1b, 1c, and 1d of embodiment 4 of the present invention, it is preferable that in embodiments 1 to 3, the photocatalyst particles 3 include a visible-light-responsive photocatalyst. In the photocatalyst compositions 1, 1a, 1b, 1c, and 1d of embodiment 5 of the present invention, in embodiment 4, the photocatalyst particles 3 may be composed of tungsten oxide, titanium dioxide that functions in the visible light region, or a mixture thereof.
According to the above configuration, the photocatalyst particles include a visible light-responsive photocatalyst such as tungsten oxide or titanium dioxide modified to function also in the visible light region, and thus exhibit photocatalytic activity by absorbing visible light. This allows the decomposition of the decomposition target substance at a wavelength longer than that of the ultraviolet-responsive photocatalyst. Therefore, a photocatalyst composition which can stably exhibit adsorption performance and decomposition performance even in a situation where ultraviolet rays are very little, such as indoors and in automobiles, can be provided.
In the photocatalyst compositions 1, 1a, 1b, 1c, and 1d according to embodiment 6 of the present invention, it is preferable that the adsorbent particles 2 include zeolite, sepiolite, mesoporous silica, activated clay, or a mixture of a plurality of these substances in embodiments 1 to 5.
According to the above configuration, the adsorbent particles include zeolite, sepiolite, mesoporous silica, activated clay, or a mixture of a plurality of these substances, which have high light transmittance particularly in the wavelength region from visible light to near ultraviolet. This enables light to reliably reach the photocatalyst particles present inside the photocatalyst composition. Therefore, the adsorption performance and the decomposition performance of the photocatalyst composition can be sustained for a long period of time.
The photocatalyst compositions 1, 1a, 1b, 1c, and 1d of embodiment 7 of the present invention are preferably in the form of pellets in embodiments 1 to 6.
According to the above configuration, since the photocatalyst compositions 1, 1a, 1b, 1c, and 1d are in the form of pellets, a block having a certain volume can be used as it is without requiring another carrier or the like as compared with the case of using the photocatalyst compositions in the form of powder, within a range in which the gas adsorption/decomposition performance is not deteriorated. Therefore, the method can be used easily in terms of processing.
The photocatalyst compositions 1, 1a, 1b, 1c, and 1d of embodiment 8 of the present invention may be in the form of substantially spherical pellets in embodiment 7, and have a diameter of 0.5mm or more and 5mm or less. This allows the photocatalyst composition to be reliably impregnated with the decomposition target while maintaining the ease of handling.
The photocatalyst composition 1d according to embodiment 9 of the present invention may be configured such that the distribution density of photocatalyst particles is highest on the surface of the photocatalyst composition 1d in embodiments 1 to 8.
According to the above configuration, the photocatalyst particles 3 are densely distributed on the surface of the photocatalyst composition 1d and are sparsely distributed in the interior, and therefore the photocatalyst particles 3 carried on the surface receive light directly, and the decomposition efficiency is high.
Further, if the voids 6 are formed in the photocatalyst composition 1d, the surface of the photocatalyst composition 1d is not entirely covered with the photocatalyst particles 3, and the adsorbent particles 2 are exposed to the surface. This allows the adsorbent to exhibit its adsorption performance and the photocatalyst to exhibit its decomposition performance on the surface and in the interior. Therefore, the adsorption performance of the adsorbent and the decomposition performance of the photocatalyst can be maintained more reliably, and both can be more reliably satisfied.
In the photocatalyst composition 1 of embodiment 10 of the present invention, in embodiments 1 to 8, the composition ratio of the adsorbent particles 2 and the photocatalyst particles 3 may be uniform in the inside of the photocatalyst composition 1.
According to the above constitution, the adsorbent particles and the photocatalyst particles are uniformly present in the photocatalyst composition. Therefore, a photocatalyst composition which always maintains an optimum balance of adsorption and decomposition can be provided.
In the photocatalyst composition 1 according to embodiment 11 of the present invention, in embodiments 1 to 8, the composition ratio of the adsorbent particles and the photocatalyst particles may be increased or decreased as the photocatalyst composition is moved into the photocatalyst composition.
According to the above configuration, since the composition ratio of the adsorbent particles and the photocatalyst particles changes as the photocatalyst composition is moved into the photocatalyst composition, the adsorbent particles and the photocatalyst particles are unevenly distributed in the photocatalyst composition. Thus, when the adsorbent particles decrease with the passage to the inside, a photocatalyst composition in which adsorption is emphasized for a short period of time and decomposition is emphasized for a long period of time can be realized. On the other hand, when the adsorbent particles increase with the passage to the inside, the photocatalyst composition in which decomposition is emphasized in the short term and adsorption is emphasized in the long term can be realized.
The photocatalyst compositions 1, 1a, 1b, 1c, and 1d of embodiment 12 of the present invention may further contain a binder in embodiments 1 to 11. This makes it possible to facilitate the molding of the photocatalyst composition and to easily produce the photocatalyst composition.
A method for producing the photocatalyst compositions 1, 1a, 1b, 1c, and 1d according to embodiment 13 of the present invention is a method for producing a solid photocatalyst composition, the photocatalyst composition containing: adsorbent particles having at least one of light transmittance and light reflectance; and photocatalyst particles, the above production method comprising: and a dispersion step of dispersing the adsorbent particles and the photocatalyst particles from the surface of the photocatalyst composition toward the inside thereof.
According to the above configuration, it is possible to produce a photocatalyst composition capable of sustaining both the adsorption performance and the decomposition performance and a photocatalyst composition capable of maintaining both the adsorption performance and the decomposition performance.
In embodiment 13, the method for producing the photocatalyst compositions 1, 1a, 1b, 1c, and 1d according to embodiment 14 of the present invention may be such that the dispersing step includes: a mixing step of mixing the adsorbent particles and the photocatalyst particles; and a molding step of molding the adsorbent particles and the photocatalyst particles mixed in the mixing step. Thus, the photocatalyst composition can be easily produced.
The method for producing the photocatalyst composition 1d according to embodiment 15 of the present invention may be such that embodiment 14 includes: and a supporting step of further supporting the photocatalyst particles 3 on the surface of the molded article obtained in the molding step.
With the above configuration, the photocatalyst composition 1d having the highest distribution density of the photocatalyst particles 3 on the surface of the photocatalyst composition 1d can be easily produced.
In embodiment 13 of the present invention, a method for producing the photocatalyst compositions 1, 1a, 1b, 1c, and 1d of embodiment 16 may be such that the dispersion step includes: a molding step of forming a molded article having a void formed therein by using the adsorbent particles and a thermoplastic binder or by using the adsorbent particles and a thermosetting binder; and a supporting step of supporting the photocatalyst particles on the surface of the molded article having the voids formed therein.
According to the above configuration, it is possible to easily produce a photocatalyst composition capable of sustaining both the adsorption performance and the decomposition performance and a photocatalyst composition capable of satisfying both the adsorption performance and the decomposition performance.
A method for producing a photocatalyst composition 1d according to mode 17 of the present invention may be a method in which, in mode 16, the molding step is performed with a thermoplastic binder by heating, and in the supporting step, the photocatalyst particles are supported on a surface of the molded article having the voids formed therein by an impregnation method, and the method includes, after the supporting step: and a fixing step of fixing the photocatalyst particles to the thermoplastic adhesive by softening the thermoplastic adhesive by heating and then curing the softened thermoplastic adhesive.
According to the above configuration, in the supporting step, the photocatalyst particles are supported in the inside of the molded article having the voids formed therein by impregnating the dispersion of the photocatalyst particles into the voids, and then the fixing step is performed. Thus, the photocatalyst particles can be fixed to the thermoplastic adhesive by heating in the fixing step. Therefore, the photocatalyst composition 1d having the highest distribution density of the photocatalyst particles 3 on the surface of the photocatalyst composition 1d can be easily produced.
A method for producing a photocatalyst composition 1d according to embodiment 18 of the present invention may be such that, in embodiment 16, the molding step is performed by heating with a thermosetting adhesive that cures under a plurality of conditions, and in the supporting step, the photocatalyst particles are supported on the surface of the molded article having the voids formed therein by an impregnation method, and the method includes, after the supporting step: and a fixing step of fixing the photocatalyst particles to a thermosetting adhesive by curing the thermosetting adhesive under a curing condition different from that in the molding step.
According to the above configuration, the first step 1 of the forming step is to form: a formed article having voids is formed. In the supporting step, the photocatalyst particles are supported in the inside of the molded article having the voids formed therein by impregnating the photocatalyst particles with the dispersion liquid, and then the fixing step is performed. This allows the photocatalyst particles 3 to be fixed to the 2-stage thermosetting adhesive by the 2 nd-stage curing in the fixing step. Therefore, the photocatalyst composition 1d having the highest distribution density of the photocatalyst particles 3 on the surface of the photocatalyst composition 1d can be easily produced.
The gas adsorption/decomposition pellet of embodiment 21 of the present invention is a pellet obtained by mixing a powdery adsorbent and a powdery photocatalyst and fixing the mixture as an aggregate of the powders and molding the mixture into a block, wherein the adsorbent has light transmittance and the photocatalyst is a visible light-responsive type.
According to the above configuration, since a sufficient amount of photocatalyst can be secured, a gas adsorbing/decomposing pellet having high gas adsorbing/decomposing performance and hardly deteriorating gas decomposing performance even after long-term use can be realized.
In the gas adsorption/decomposition pellet according to mode 22 of the present invention, in mode 21, the adsorbent may include zeolite, sepiolite, or a mixture thereof.
According to the above configuration, the adsorbent particularly has light transmittance, so that light energy can sufficiently reach the inside of the pellet, and high gas decomposition performance can be achieved.
The gas adsorption/decomposition pellet according to embodiment 23 of the present invention may be used. In mode 21 or 22, the photocatalyst includes tungsten trioxide (WO)3) Titanium dioxide (TiO) modified to function also in the visible region by introducing specific metal ions or by introducing nitrogen to the oxygen site2) Or mixtures thereof.
According to the above configuration, since the photocatalyst having a characteristic of reacting with visible light in particular can be configured, the gas can be decomposed at a longer wavelength than the photocatalyst reacting with ultraviolet light, and light having a longer wavelength than the light transmittance of a general adsorbent can be used, and thus high gas decomposition performance can be achieved.
The gas adsorption/decomposition pellet of the mode 24 of the present invention may be substantially spherical in the modes 21 to 23, and the diameter thereof may be in the range of 0.5mm to 5 mm.
According to the above configuration, compared with the case of using the powder, the block having a certain volume can be used as it is without using another carrier or the like within a range not to lower the gas adsorption/decomposition performance, and therefore, the block can be used easily in terms of handling.
In the gas adsorption/decomposition pellet of mode 25 of the present invention, in modes 21 to 24, the presence ratio of the adsorbent and the photocatalyst may be uniform at each position inside the pellet.
According to the above configuration, even when the long-term use is performed and, for example, chipping or the like occurs, the ratio of the adsorbent to the photocatalyst can be always kept constant and the photocatalyst can be operated at an optimum ratio in a uniform manner, and therefore, the degradation of the gas adsorption/decomposition performance due to the long-term use can be reduced.
The gas adsorption/decomposition pellet of the mode 26 of the present invention may be such that in the modes 21 to 25, the presence ratio of the adsorbent and the photocatalyst can be expressed as a function of the distance from the surface of the pellet.
According to the above configuration, the concentration changes as the gas and light permeate from the surface of the shot, but the optimum ratio of the adsorbent to the photocatalyst can be freely set based on this.
The present invention is not limited to the above embodiments, and various modifications can be made within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. It is also possible to form new technical features by combining the technical features disclosed in the respective embodiments.
Industrial applicability of the invention
The photocatalyst composition of the present invention can be suitably used for air purifiers and deodorizers, and can be suitably used in homes, meeting rooms, stores, factories, medical facilities, automobiles, electric trains, ships, aircrafts, and the like as the use place.
Description of the reference numerals
1. 1a, 1b, 1c, 1 d: photocatalyst composition
2: adsorbent particles
3: photocatalyst particles
6: a void.
Claims (17)
1. A photocatalyst composition for use in a photocatalyst for the treatment of a high-temperature or high-pressure gas,
a photocatalyst composition which is a solid state comprising: adsorbent particles having at least one of light transmittance and light reflectance; and photocatalyst particles, the photocatalyst composition being characterized in that,
the above-mentioned adsorbent particles and photocatalyst particles exist in a dispersed state,
the distribution density of the adsorbent particles on the surface of the photocatalyst composition is higher than that in the interior.
2. The photocatalyst composition as set forth in claim 1,
a void is formed.
3. The photocatalyst composition as set forth in claim 2,
the void accounts for 30 to 50 vol% based on 100 vol% of the photocatalyst composition.
4. The photocatalyst composition as set forth in any one of claims 1 to 3,
the photocatalyst particles include visible light-responsive photocatalysts.
5. The photocatalyst composition as set forth in claim 4,
the photocatalyst particles include tungsten oxide, titanium oxide that functions in the visible light region, or a mixture thereof.
6. The photocatalyst composition as set forth in any one of claims 1 to 3 and 5,
the adsorbent particles include zeolite, sepiolite, mesoporous silica, activated clay, or a mixture of a plurality of these substances.
7. The photocatalyst composition as set forth in any one of claims 1 to 3 and 5,
is in the form of pill.
8. The photocatalyst composition as set forth in claim 7,
the pellet has a substantially spherical shape, and has a diameter of 0.5mm or more and 5mm or less.
9. The photocatalyst composition as set forth in any one of claims 1 to 3, 5 and 8,
the compositional ratio of the above adsorbent particles and photocatalyst particles is uniform inside the photocatalyst composition.
10. The photocatalyst composition as set forth in any one of claims 1 to 3, 5 and 8,
the composition ratio of the above-mentioned adsorbent particles and photocatalyst particles decreases as they go to the inside of the photocatalyst composition.
11. The photocatalyst composition as set forth in any one of claims 1 to 3, 5 and 8,
also contains a binder.
12. A process for producing a photocatalyst composition comprising a step of,
the photocatalyst composition is a solid state and contains: adsorbent particles having at least one of light transmittance and light reflectance; and photocatalyst particles, characterized in that,
comprises the following steps: and a dispersing step of dispersing the adsorbent particles and the photocatalyst particles from the surface of the photocatalyst composition toward the inside thereof so that the distribution density of the adsorbent particles on the surface of the photocatalyst composition is higher than that in the inside thereof.
13. The method for producing a photocatalyst composition according to claim 12,
the dispersing step includes:
a mixing step of mixing the adsorbent particles and the photocatalyst particles; and
and a molding step of molding the adsorbent particles and the photocatalyst particles mixed in the mixing step.
14. The method for producing a photocatalyst composition according to claim 13,
comprises the following steps: and a supporting step of further supporting photocatalyst particles on the surface of the molded article obtained in the molding step.
15. The method for producing a photocatalyst composition according to claim 12,
the dispersing step includes:
a molding step of forming a molded article having a void formed therein by using the adsorbent particles and a thermoplastic binder or by using the adsorbent particles and a thermosetting binder; and
and a supporting step of supporting the photocatalyst particles on the surface of the molded article having the voids formed therein.
16. The method for producing a photocatalyst composition as claimed in claim 15,
in the molding step, the molding is carried out by heating using a thermoplastic adhesive,
in the supporting step, the photocatalyst particles are supported on the surface of the molded article having the voids formed therein by an impregnation method,
the method comprises the following steps: and a fixing step of fixing the photocatalyst particles to the thermoplastic adhesive by softening the thermoplastic adhesive by heating and then curing the softened thermoplastic adhesive.
17. The method for producing a photocatalyst composition as claimed in claim 15,
in the molding step, thermosetting adhesive cured under a plurality of conditions is used for thermoforming,
in the supporting step, the photocatalyst particles are supported on the surface of the molded article having the voids formed therein by an impregnation method,
the method comprises the following steps: and a fixing step of fixing the photocatalyst particles to a thermosetting adhesive by curing the thermosetting adhesive under a curing condition different from that in the molding step.
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| JP2014259410A JP5851578B1 (en) | 2014-08-27 | 2014-12-22 | Photocatalyst composition and method for producing the same |
| PCT/JP2015/064592 WO2016031319A1 (en) | 2014-08-27 | 2015-05-21 | Photocatalyst composition and method for producing same |
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| JP5851578B1 (en) | 2016-02-03 |
| WO2016031319A1 (en) | 2016-03-03 |
| JP2016047516A (en) | 2016-04-07 |
| CN106794456A (en) | 2017-05-31 |
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