CN100478074C - Catalyst-supporting fiber structure and method for producing same - Google Patents

Abstract

The present invention provides a catalyst-carrying fiber structure in which a catalyst is supported on fibers constituting a fiber structure, wherein the fiber structure has an average fiber diameter of 1 μm or less and does not substantially contain fibers having a fiber length of 20 μm or less , with sufficient flexibility and catalyst loading performance. The fiber structure has excellent catalyst supporting properties, and therefore, for example, a fiber structure having an extremely high ability to decompose harmful substances can be provided.

Description

Catalyst-loaded fiber structure and preparation method thereof

technical field

The present invention relates to a catalyst-loaded fiber structure in which a catalyst is supported on fibers constituting the fiber structure and a method for producing the same.

Background technique

In recent years, with the deterioration of the earth's environment, environmental problems have increasingly become social problems, and people are increasingly concerned about environmental problems. With the seriousness of environmental problems, the development of technologies capable of highly removing harmful chemical pollutants has been desired. Among them, people are worried about the profound impact of benzene, trichlorethylene and other VOCs (volatile organic compounds), phthalates and other endocrine disrupting substances on the human body, especially for wastewater containing these substances, in addition to wishing to set up large-scale treatment Beyond facilities, people have also begun to seek ways to virtually eliminate them entirely at their respective sources.

Regarding the removal method of these chemical pollutants, someone has studied the method that microorganisms are used as a catalyst for decomposing harmful substances in waste water. Patent Document 1). However, in this method, there is a problem of poor treatment efficiency because the amount of microorganisms supported is limited.

Research and development of adsorbents, catalysts, and the like for removing and decomposing harmful substances in wastewater are also being carried out. Among them, attention has been paid to titanium oxide having photocatalytic activity as a catalyst capable of decomposing harmful substances. That is, when a photocatalyst containing titanium oxide is irradiated with light having a wavelength of energy above the band gap, electrons are generated in the conduction band and holes are generated in the valence band by photoexcitation, and the electrons and holes generated by the photoexcitation can be The high reducing power and oxidizing power are used for the decomposition of harmful substances.

For example, it has been proposed that a photocatalytic titanium oxide is supported on porous whiskers having a specific specific surface area to form photocatalytic whiskers (for example, refer to Patent Document 2). However, in order to use the whiskers obtained by this method for actual wastewater treatment, the whiskers must be contained in paint, rubber, etc., and the operation is complicated, and the catalyst loading amount in the final use form is reduced.

It has also been proposed to support titanium dioxide on the surface of titanium dioxide fibers having a specific specific surface area or less to produce titanium dioxide fibers for photocatalysis (for example, refer to Patent Document 3). However, the titania fiber of this method also has a problem that the amount of catalyst supported is small. In addition, titanium dioxide fibers lack softness, so the form of use is limited.

As an example of using a more flexible raw material, it is shown that a photocatalyst is supported on a woven or nonwoven fabric, more specifically, a photocatalyst is supported on an aramid fiber cloth, a fluororesin cloth, etc. properties (for example, refer to Patent Document 4), but there is still the problem of a small amount of catalyst loading.

[Patent Document 1] Japanese Patent Laid-Open No. 2000-288569

[Patent Document 2] Japanese Unexamined Patent Publication No. 2000-271488

[Patent Document 3] Japanese Patent Laid-Open No. 2000-218170

[Patent Document 4] Japanese Patent Application Laid-Open No. 9-267043

Contents of the invention

A first object of the present invention is to provide a fibrous structure having sufficient flexibility and catalyst-supporting performance while eliminating the above-mentioned problems of the prior art.

Another object of the present invention is to provide a method for producing a fibrous structure having a high ability to decompose harmful substances in an extremely simple method.

Brief description of the drawings

Fig. 1 is a schematic diagram of a production apparatus for explaining one aspect of the production method of the present invention.

Fig. 2 is a schematic diagram of a production apparatus for explaining one aspect of the production method of the present invention.

3 is an electron micrograph (magnification: 2000 times) taken of the surface of the fibrous structure obtained by the operation of Example 1. FIG.

Fig. 4 is an electron micrograph of the surface of the fibrous structure obtained by the operation of Example 1 taken with a scanning electron microscope (magnification: 8000 times).

5 is an electron micrograph (magnification: 5000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 1. FIG.

Fig. 6 is an electron micrograph of the surface of the fibrous structure obtained by the operation of Example 2 taken with a scanning electron microscope (magnification: 2000 times).

Fig. 7 is a scanning electron microscope photograph of the surface of the fibrous structure obtained by the operation of Example 2 (magnification: 8000 times).

Fig. 8 is an electron micrograph of the surface of the fibrous structure obtained by the operation of Example 3 taken with a scanning electron microscope (magnification: 20,000 times).

9 is an electron micrograph (magnification: 20,000 times) taken with a scanning electron microscope on the surface of the fibrous structure obtained by the operation of Example 4. FIG.

10 is an electron micrograph (magnification: 8000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 5. FIG.

11 is an electron micrograph (magnification: 20,000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 5. FIG.

Fig. 12 is the X-ray diffraction pattern of the fiber structure of the loaded catalyst obtained by the operation of Example 5, in the graph of Fig. 12, vertical axis is X-ray diffraction intensity (cps), and horizontal axis is diffraction angle 2θ (deg .).

13 is an X-ray diffraction pattern of the fiber structure obtained by the operation of Comparative Example 3. In the graph of FIG. 13 , the vertical axis represents the X-ray diffraction intensity (cps), and the horizontal axis represents the diffraction angle 2θ (deg.).

14 is an electron micrograph (magnification: 8000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 6. FIG.

15 is an electron micrograph (magnification: 8000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 7. FIG.

16 is an electron micrograph (magnification: 2000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 8. FIG.

17 is an electron micrograph (magnification: 8000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 9. FIG.

18 is an electron micrograph (magnification: 8000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 10. FIG.

19 is a scanning electron microscope photograph of the surface of the catalyst-carrying fiber structure obtained by the operation of Example 11 (magnification: 2000 times).

20 is an electron micrograph (magnification: 2000 times) taken with a scanning electron microscope of the surface of the catalyst-carrying fibrous structure obtained by the operation of Example 12. FIG.

21 is a scanning electron microscope photograph of the surface of the catalyst-carrying fiber structure obtained by the operation of Example 13 (magnification: 2000 times).

22 is an electron micrograph of the surface of the fibrous structure obtained by the operation of Comparative Example 4 taken with a scanning electron microscope (magnification: 8000 times).

Fig. 23 is an electron micrograph of the surface of the fibrous structure obtained by the operation of Comparative Example 5 taken with a scanning electron microscope (magnification: 8000 times).

The best way to practice the invention

The present invention is described in detail below.

In the present invention, "fibrous structure" refers to a three-dimensional structure formed by knitting, weaving, lamination, etc. of fibers, and a preferred example is a nonwoven fabric.

The average fiber diameter of the fibers forming the fibrous structure of the present invention must be 1 μm or less. When the average fiber diameter exceeds 1 μm, the specific surface area of the fiber becomes small, so the amount of the catalyst that can be supported decreases. In addition, if the average diameter of the fibers is 0.01 μm or more, the strength of the resulting fibrous structure is sufficient. The average diameter of the fibers constituting the fibrous structure is preferably in the range of 0.01 to 0.7 μm.

The fibrous structure of the present invention does not substantially contain fibers having a fiber length of 20 μm or less. Here, the term “substantially free” means that no fiber having a fiber length of 20 μm or less is observed at any position observed with a scanning electron microscope. If the fiber length is 20 μm or less, the mechanical strength of the obtained fiber structure is insufficient, which is not preferable. In the present invention, fibers having a fiber length of 40 μm or less are preferably not contained, and fibers having a fiber length of 1 mm or less are more preferably not contained.

The catalyst supported on the fibers constituting the fiber structure is not particularly limited as long as it is a catalyst capable of decomposing harmful substances. For example, there are photocatalysts such as titanium oxide, inorganic compounds such as allophane and fly ash, and white rot fungi. , trichlorethylene decomposing bacteria and other microbial catalysts, various enzymes, etc. Among them, from the standpoints of operability, activity, etc., inorganic compounds are preferably used, photocatalysts are particularly preferred, and titanium oxide is particularly preferably used. When titanium oxide is used, fine particles are easily supported on fibers, which is preferable.

When a photocatalyst is used as a catalyst, a part of the surface of the photocatalyst is covered with another inorganic compound, and a fiber structure carrying the catalyst exhibits high catalytic activity, which is more preferable. Other inorganic compounds covering the surface of the photocatalyst include ceramics such as silicon dioxide and apatite.

In the present invention, as long as the above-mentioned catalyst is supported on the fibers constituting the fibrous structure, it may be in any supported state, for example, it may be (a) attached to the surface of the fibers constituting the fibrous structure, (b) contained in Inside the fiber, a part of the catalyst is exposed and contained on the fiber surface. (c) The state is that the catalyst is in the form of particles in the range of 1-100 μm in diameter, and the particles are contained in the fiber structure, and the contained catalyst particles are contained in the fiber structure. The non-contact portion between the catalyst particle and the fiber constituting the fiber structure exists, and the surface of the contained catalyst particle includes the catalyst particle and the non-contact portion with the fiber. Here, in the present invention, internal inclusion refers to the state in which the catalyst does not slip from the fiber structure, and it is particularly preferred that the catalyst particles are in contact with at least one or more fibers on the surface, and the catalyst particles are embedded in the fiber structure. .

In the above supported fiber structure of (a), there is a high possibility that the catalyst will come off from the fiber structure, but since the surface of the catalyst can be effectively used, it can be used in applications where catalyst fall-off factors such as mechanical stress and deformation are less likely to occur.

In the supported state of the above-mentioned (b) fiber structure, the exposed area of the catalyst surface is smaller than that of the above-mentioned supported state of (a), but it is difficult for the catalyst to fall off from the catalyst fiber structure, so it can be used in the case where the above-mentioned (a) is not suitable. The use of the catalyst detachment factor of the fiber structure in the supported state is prone to occur.

The fiber structure in the supported state of (c) is between the supported state of (a) and the supported state of (c).

Here, in the supported state of (c) above, the particle size of the catalyst must be in the range of 1 to 100 μm. If the particle size is smaller than 1 μm, the specific surface area of the catalyst that can contribute to the reaction increases, but the absolute surface area is too small, which is not preferable. On the other hand, if it exceeds 100 μm, the absolute area of the catalyst capable of contributing to the reaction increases, but the specific surface area of the catalyst is too small.

The particle size mentioned here refers to the average value of the largest part of the particle diameters carried in the fiber structure, which can be the primary particle size, or the aggregate formed by the aggregation of catalyst particles in the fiber structure (so-called The value of the particle diameter of the secondary aggregated particles), the catalyst with the primary particle diameter in the range of 1-100 μm shows higher activity and is thus preferred. A more preferred particle size is 1.5 μm to 30 μm.

In the present invention, to obtain the supported state of the above (a)-(c), it can be appropriately selected according to the target application, and a plurality of fiber structures can also be stacked and made into a composite form by laminating, for example, the above (b) ) in the loaded state of the fiber structure is arranged on the outermost side, and the above-mentioned fiber structure in the supported state of (a) is arranged on the innermost side, which can reduce the catalyst shedding of the entire fiber structure, or by the opposite arrangement, While keeping the catalyst in the entire fibrous structure, a part of the catalyst in the fibrous structure is intentionally detached.

The fibers forming the fibrous structure of the present invention are fibers containing organic polymers in terms of mechanical properties and handleability.

Examples of the above-mentioned organic polymers are: polyacrylonitrile, polymethyl methacrylate, polyethyl methacrylate, poly-n-propyl methacrylate, poly-n-butyl methacrylate, polymethyl acrylate, polyethyl methacrylate ester, polybutyl acrylate, polyacrylonitrile/methacrylate copolymer, polyvinylidene chloride, polyvinyl chloride, polyvinylidene chloride/acrylate copolymer, polyethylene, polypropylene, poly-4-methyl Amylpentene-1, polystyrene, aramid, poly-p-phenylene terephthalamide, poly-p-phenylene terephthalamide/3,4'-oxydiphenylene-p-phenylene Dicarboxamide copolymer, polym-phenylene isophthalamide, polybenzimidazole, polypyromellitic tere-phenylene diimide, poly-4,4'-oxydiphenylene pyromellitic tetramethylene Formimide, Polyvinyl Alcohol, Cellulose, Cellulose Diacetate, Cellulose Triacetate, Methyl Cellulose, Propyl Cellulose, Benzyl Cellulose, Cellulose Acetate/Butyrate, Polyethylene Ethyl sulfide, polyvinyl acetate, polyethylene terephthalate, polyethylene naphthalate, polylactic acid, polyglycolic acid, polylactic acid/polyglycolic acid copolymer, polycaprolactone, poly Glutamic acid, polyarylate, polycarbonate, polyethersulfone, polyetherethersulfone, polyvinylidene fluoride, polyurethane, polybutylene succinate, polyethylene succinate, polyhexyl carbonate, poly Vinyl isocyanate, polybutyl isocyanate, polyvinyl acetate, polyvinyl methyl ether, polyvinyl ethyl ether, polyvinyl n-propyl ether, polyvinyl isopropyl ether, polyvinyl n-butyl Ether, polyvinyl isobutyl ether, polyvinyl tert-butyl ether, poly(N-vinylpyrrolidone), poly(N-vinylcarbazole), poly(4-vinylpyridine), polyvinylmethyl ether Base ketone, polymethyl isopropenyl ketone, polyethylene oxide, polypropylene oxide, polycyclopentene oxide, polystyrene sulfone, nylon 6, nylon 66, nylon 11, nylon 12, nylon 610, nylon 612 , polyvinylidene fluoride, polyvinyl bromide, polychlorotrifluoroethylene, polychloroprene, ring-opening polymers of norbornene-based monomers and their hydrides, fibroin, natural rubber, chitin, Acetyl chitin, collagen, zein, etc., they can be copolymerized substances or mixtures, which can be selected from various angles.

As an example of the above-mentioned selection, for example, from the viewpoints of operability and physical properties, polyacrylonitrile and their copolymers, or compounds obtained by heat-treating them, can be used. The impact of the catalyst, the fiber structure itself does not decompose, and organic polymers containing halogen elements (such as polyvinyl chloride, polyvinylidene chloride, polyvinylidene chloride-acrylate copolymer, polyvinylidene fluoride, polyvinylidene fluoride, Polyvinyl bromide, polychlorotrifluoroethylene, polychloroprene, etc.), polyvinyl chloride is particularly preferred to make the fiber structure biodegradable, and can be naturally decomposed in the soil after long-term use, and polylactic acid can also be used .

After the fibers are formed, heat-treated or chemically-treated fibers can be used, and if necessary, emulsions or powders of organic and inorganic substances can be mixed with the above-mentioned polymers for use.

The catalyst-carrying fiber structure of the present invention may be used alone, or may be used in combination with other members in consideration of handleability or other requirements. For example, a nonwoven or woven fabric, a film, etc. can be used as a support base for the collecting base, and a fiber laminate is formed thereon to form a member combining the support base and the fiber laminate.

The catalyst-carrying fiber structure of the present invention may be prepared by any method as long as the catalyst-carrying fiber structure having the above average fiber diameter and fiber length can be obtained.

Hereinafter, in an aspect of producing the catalyst-supported structure of the present invention, a method for producing the supported state of (a) to (c) above will be described.

The fiber structure having the supported state of (a) above can be obtained, for example, by a method for producing a catalyst-supported fiber structure comprising: a step of dissolving a fibrous organic polymer to prepare a solution; electrospinning The step of spinning the above-mentioned solution; the step of obtaining a fiber structure accumulated on the collection substrate by the above-mentioned spinning; and the step of loading the catalyst on the above-mentioned fiber structure.

Here, the electrospinning method is to dissolve the fibrous compound to make a solution, spray the solution into the electrostatic field formed between the electrodes, draw the solution toward the electrode, and accumulate the formed fibrous substance on the collection substrate. Above, the method of obtaining a fibrous structure in this way; the fibrous substance is not only a state in which the solvent for dissolving the fibrous compound is distilled off to form a fiber laminate, but also a state in which the solvent is contained in the fibrous substance.

Next, an apparatus used in the electrospinning method will be described.

The above-mentioned electrode may be any metal, inorganic or organic material as long as it exhibits conductivity, and may also be in the form of a thin film having a conductive metal, inorganic or organic substance on an insulator.

An electrostatic field is formed between a pair or more electrodes, and a high voltage can be applied to any electrode. This also includes the case of using, for example, two high-voltage electrodes (for example, 15 kV and 10 kV) with different voltage values, and a ground electrode, or three electrodes in total, or the case of using more than three electrodes.

Next, a method for producing fibers constituting the fiber structure of the present invention by an electrospinning method will be described in order.

First, the fibrous organic polymer is dissolved to prepare a solution. Here, the concentration of the fibrous organic polymer in the solution is preferably 1 to 30% by weight. If the concentration is less than 1% by weight, the concentration is too low, making it difficult to form a fibrous structure, which is not preferable. On the other hand, if it is larger than 30% by weight, the average diameter of the fibers obtained will increase, which is not preferable. A more preferred concentration is 2-20% by weight.

The above-mentioned solvent for dissolving the organic polymer is not particularly limited as long as it dissolves the fibrous organic polymer and is capable of evaporating to form fibers at the stage of spinning by the electrospinning method. Examples are acetone, chloroform, ethanol, isopropanol, methanol, toluene, tetrahydrofuran, water, benzene, benzyl alcohol, 1,4-dioxane, propanol, methylene chloride, carbon tetrachloride, cyclohexane, cyclohexane, Hexanone, phenol, pyridine, trichloroethane, acetic acid, formic acid, hexafluoroisopropanol, hexafluoroacetone, N,N-dimethylformamide, acetonitrile, N-methylmorpholine-N-oxide, 1,3-dioxolane, methyl ethyl ketone, N-methylpyrrolidone, a mixed solvent of the above solvents, and the like.

Among these, N,N-dimethylformamide, tetrahydrofuran, chloroform, and a mixed solvent of N,N-dimethylformamide and tetrahydrofuran are preferably used in view of handling properties, physical properties, and the like.

Next, the step of spinning the above-mentioned solution by the electrospinning method will be described. The method of spraying the solution into the electrostatic field can be any method, for example, the solution can be supplied to a nozzle, the solution can be placed in an appropriate position in the electrostatic field, and the solution can be drawn from the nozzle by the electric field to form fibers.

Hereinafter, it demonstrates more concretely using FIG. 1. FIG.

At the top of the cylindrical solution holding tank (3 of FIG. 1 ) of the syringe, a needle-shaped solution nozzle (1 of FIG. 1 ) for applying a voltage through an appropriate device (such as a high-voltage generator (6 of FIG. 1 ) is provided, Direct the solution (2 of Figure 1) to the tip of the solution nozzle. Set the top of the solution nozzle (1 of Fig. 1) at an appropriate distance from the grounded fibrous substance collecting electrode (5 of Fig. 1), and the solution (2 of Fig. 1) is sprayed from the top of the solution nozzle (1 of Fig. 1) Fibrous matter can be formed between the tip portion of the nozzle and the fibrous matter collecting electrode (5 in FIG. 1 ).

Other solutions are illustrated in Figure 2. The fine droplets of the solution (not shown) can be introduced into the electrostatic field. At this time, the only requirement is to place the solution (2 of Figure 2) in the electrostatic field and keep it with the fibrous substance collecting electrode (5 of Figure 2). The distance at which fibers can be formed. For example, the electrode (4 of Fig. 2) opposite to the fibrous substance collecting electrode can be directly inserted into the solution (2 of Fig. 2) in the solution holding tank (3 of Fig. 2) with the solution nozzle (1 of Fig. 2) .

When the solution is supplied to an electrostatic field from a nozzle, a plurality of nozzles can be used in parallel to increase the production rate of the fibrous substance. In addition, the distance between the electrodes is related to the amount of charge, the size of the nozzle, the amount of solution sprayed from the nozzle, and the concentration of the solution. It is appropriate to keep a distance of 5-20cm when the voltage is about 10kV. In addition, the applied electrostatic potential is usually 3-100 kV, preferably 5-50 kV, more preferably 5-30 kV. A desired potential can be obtained by any appropriate method known in the past.

The above two schemes are the case where the electrodes also serve as the collecting substrate. By placing an object that can serve as the collecting substrate between the electrodes, the collecting substrate can be provided independently of the electrodes, and the fiber laminate can be collected thereon. In this case, for example, a strip-shaped substance is provided between electrodes as a collection substrate, so that continuous production can be performed.

Next, the stage of obtaining the fibrous structure accumulated on the collection substrate will be described. In the present invention, during the drawing of the solution toward the collection substrate, depending on the conditions, the solvent evaporates to form a fibrous substance. If it is normal room temperature, the solvent is completely evaporated before being collected on the collection substrate, but if the solvent is not evaporated sufficiently, it can be drawn under reduced pressure. When collected on the collecting substrate, a fibrous structure is formed that satisfies at least the above average fiber diameter and fiber length. In addition, the drawing temperature is related to the evaporation properties of the solvent or the viscosity of the spinning solution, and is usually in the range of 0-50°C.

Next, the catalyst can be supported on the fiber structure obtained by the above-mentioned electrospinning method. The method of carrying the catalyst is not particularly limited, and the catalyst is brought into contact with the surface of the fiber by immersing the above-mentioned fiber structure in a liquid containing the catalyst. method, or apply a catalyst-containing liquid on the above-mentioned fibrous structure by spraying or the like, which is preferable in terms of ease of operation and uniform loading. It is preferable that the catalyst-containing liquid also contains a component capable of binding the fibrous structure and the catalyst.

Next, the fiber structure having the supported state of (b) above can be obtained, for example, by a method for producing a catalyst-supported fiber structure comprising dissolving a fibrous organic polymer and a catalyst precursor in a solvent A stage of preparing a solution; a stage of spinning the above solution by electrospinning; a stage of obtaining a fiber structure accumulated on a collecting substrate by the above spinning; treating a catalyst precursor contained in the above fiber structure , the stage of catalyst formation.

In this preparation method, firstly, a solution is prepared by dissolving a fibrous organic polymer and a catalyst precursor in a solvent. Here, the catalyst precursor may be an inorganic compound that can form a catalyst through a sol-gel reaction. Examples are metal alkoxides or metal chlorides. Specifically, there are titanium alkoxides, tin alkoxides, silicon alkoxides, aluminum alkoxides, and the like, among which titanium alkoxides are particularly preferably used. From the viewpoint of availability and the like, tetraisopropoxytitanium, tetrabutoxytitanium, and the like can be preferably used as the alkoxytitanium.

The concentration of the fibrous organic polymer relative to the solvent in the solution is preferably 1 to 30% by weight. When the concentration of the fibrous organic polymer is less than 1% by weight, the concentration is too low, making it difficult to form a fibrous structure, which is not preferable. If it is larger than 30% by weight, the fiber diameter of the resulting fibrous structure will increase, which is not preferable. A more preferable concentration of the fibroblast organic polymer relative to the solvent in the solution is 2 to 20% by weight.

The concentration of the catalyst precursor relative to the solvent in the solution is preferably 1 to 30% by weight. When the concentration of the catalyst precursor is less than 1% by weight, the amount of the catalyst produced decreases, which is not preferable. If it is larger than 30% by weight, it is difficult to form a fiber structure, which is not preferable. A more preferred concentration of the catalyst precursor is 2-20% by weight relative to the solvent in the solution.

One kind of solvent may be used alone, or a plurality of solvents may be combined. The solvent is not particularly limited as long as it can dissolve the fibrous organic polymer and the catalyst precursor, and evaporate at the stage of spinning by electrospinning so that fibers can be formed. The solvent used in the state.

In the production method of the present invention, a coordinating compound may be further combined with a solvent. The coordination compound is not particularly limited as long as it can control the reaction of the catalyst precursor and form a fibrous structure. Examples include carboxylic acids, amides, esters, ketones, phosphines, ethers, and alcohols. , Thiols, etc.

In this production method, a catalyst precursor contained in a fiber structure obtained by an electrospinning method is treated to form a catalyst.

When metal alkoxide or metal chloride is used as the catalyst precursor, hydrothermal treatment can be implemented as needed, that is, the fiber structure obtained by the above-mentioned electrospinning method is put into a closed container such as an autoclave, and is carried out in a solution or in its steam. heat treatment. The hydrothermal treatment method is not particularly limited as long as it can promote the hydrolysis of the residual metal alkoxide contained in the above-mentioned fiber structure, accelerate the polycondensation reaction of the metal hydroxide, and accelerate the crystallization of the metal oxide. The treatment temperature is preferably 50°C-250°C, more preferably 70°C-200°C. If the treatment temperature is lower than 50°C, the crystallization of the metal oxide cannot be accelerated, which is not preferable, and if it is higher than 250°C, the strength of the organic polymer used as a base material will decrease, which is not preferable. Liquid usually uses pure water, preferably pH 2-10, more preferably pH 3-9.

If necessary, the above-mentioned fiber structure can also be dried under hot air. Crystallization of metal oxides can be accelerated by drying under hot air. The above-mentioned temperature is preferably 50°C-150°C, more preferably 80°C-120°C.

Matters not described in this production method can directly refer to the description of the method for producing the supported fiber structure of (a).

The fiber structure having the supported state of (c) above can be obtained, for example, by a method for producing a catalyst-supported fiber structure comprising the steps of dissolving a fibrous compound in a solvent to prepare a solution, and then dispersing the catalyst particles The stage of preparing the dispersion solution; the stage of spinning the above-mentioned dispersion solution by electrospinning; the stage of obtaining the catalyst-loaded fiber structure accumulated on the collection substrate by the above-mentioned spinning.

First, a fibrous compound is dissolved in a solvent to prepare a solution, and catalyst particles are dispersed therein to prepare a dispersed solution. The concentration of the fibroblast compound in the dispersion solution in the production method of the present invention is preferably 1 to 30% by weight. When the concentration of the fibrous compound is less than 1% by weight, the concentration is too low, making it difficult to form a fibrous structure, which is not preferable. If it is larger than 30% by weight, the fiber diameter of the resulting fibrous structure will increase, which is not preferable. A more preferred concentration of the fibrogenic compound is 2-20% by weight.

The dispersion concentration of the catalyst particles in the dispersion solution in the production method of the present invention is preferably 0.1 to 30% by weight. When the dispersion concentration of the catalyst particles is less than 0.1% by weight, the catalytic activity of the obtained fibrous structure is too low, which is not preferable. If it is higher than 30% by weight, the strength of the obtained fiber structure will decrease, which is not preferable. A more preferable dispersion concentration of catalyst particles is 0.5-25% by weight.

In the preparation method of the present invention, the fibrous compound may be dissolved in a solvent to prepare a solution, and then the catalyst particles may be dispersed, or the fibrous compound and the catalyst particles may be added to the solvent at the same time, or the fibrous compound may be dissolved in a pre-prepared solution. Added catalyst particles to the solvent. The method for dispersing the catalyst particles is not particularly limited, and includes stirring, ultrasonic treatment, and the like.

Matters not described in this production method can directly refer to the description of the method for producing the supported fiber structure of (a).

Example

The present invention is further illustrated by the following examples, and the present invention is not limited by these examples. The evaluation items in each of the following Examples and Comparative Examples were implemented by the following methods.

Average diameter of fibers:

The surface of the obtained fiber structure was photographed with a scanning electron microscope (manufactured by Hitachi, Ltd. S-2400) (magnification 8000 times), and 20 positions were randomly selected from the obtained photographs to measure the fiber diameter and obtain the total fiber diameter. The average value of the diameters (n=20) was taken as the average diameter of the fibers.

Confirmation of the presence of fibers with a fiber length of 20 μm or less:

The surface of the obtained fibrous structure was photographed with a scanning electron microscope (manufactured by Hitachi, Ltd. S-2400) (magnification 2000 times), and the obtained photograph was observed to confirm whether there were fibers with a fiber length of 20 μm or less.

Catalyst particle size:

The surface of the obtained fiber structure was photographed with a scanning electron microscope (manufactured by Hitachi, Ltd. S-2400) (photographing magnification 8000 times), and 5 positions were randomly selected from the obtained photographs, and the diameter of the catalyst particle part was measured to obtain The average value of all diameters (n=5) was taken as the catalyst particle diameter.

The longest part of the catalyst particle within the range that can be confirmed in the photograph is taken as the diameter.

Catalyst activity evaluation:

A fibrous structure sample was cut into 2 cm in length and 2 cm in width, and immersed in 5 ml of a 10 ppm methylene blue aqueous solution.

Using the Eye Super UV Tester "SUV-F11" manufactured by Iwasaki Electric Co., Ltd., the light in the 295-450 nm region was irradiated for a predetermined time at an intensity of 60 mW/cm ² . In addition, a fiber structure not carrying a catalyst was used as a control sample, and the methylene blue aqueous solution in which the control sample was immersed was also irradiated.

The absorbance at 665 nm was measured with respect to the obtained methylene blue aqueous solution using "UV-2400PC" manufactured by Shimadzu Corporation. Among the methylene blue aqueous solution impregnated with the fiber structure carrying the catalyst and the methylene blue aqueous solution impregnated with the fiber structure not carrying the catalyst, the absorbance of the methylene blue aqueous solution impregnated with the fiber structure carrying the catalyst is small, and can be evaluated by the decomposition of methylene blue catalyst activity.

Example 1

A solution containing 1 part by weight of polyacrylonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) and 9 parts by weight of N,N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade) was prepared. Using the apparatus shown in Figure 2, the solution was sprayed onto the fibrous material collecting electrode (5 of Figure 2) for 30 minutes. The inner diameter of the nozzle (1 of FIG. 2 ) is 0.8 mm, the voltage is 12 kV, and the distance from the nozzle (1 of FIG. 2 ) to the fibrous substance collecting electrode (5 of FIG. 2 ) is 10 cm. The basis weight of the obtained fibrous structure was 3 g/m ² . Observation of the resulting fiber structure with a scanning electron microscope (S-2400 manufactured by Hitachi, Ltd.) revealed that the average fiber diameter was 0.2 μm, and fibers with a fiber length of 20 μm or less were not observed. The scanning electron micrographs of the obtained fiber structure are shown in Fig. 3 and Fig. 4 .

Next, the obtained fiber structure was immersed in a photocatalyst coating agent ("PALTITAN 5607" manufactured by Japan Parkerizing Co., Ltd.) for 10 minutes, and then dried to obtain a catalyst-loaded fiber structure. The final catalyst activity evaluation results are shown in the table 1. A scanning electron micrograph of the obtained catalyst-loaded fiber structure is shown in FIG. 5 .

Example 2

In Example 1, the same operation was performed except that the fiber structure was formed and then heat-treated at 300° C. for 3 hours.

When the fiber structure obtained after the heat treatment was observed with a scanning electron microscope (S-2400 manufactured by Hitachi, Ltd.), the average fiber diameter was 0.2 μm, and fibers with a fiber length of 20 μm or less were not observed. The scanning electron micrographs of the obtained fiber structure are shown in Fig. 6 and Fig. 7 .

The obtained fiber structure was subjected to the same operation as in Example 1 to obtain a catalyst-carrying fiber structure. The final catalyst activity evaluation results are shown in Table 1.

Comparative example 1

Polyacrylonitrile (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in N,N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade) to prepare a dope having a polymer concentration of 7.5%.

This was extruded into a coagulation bath using water as a coagulation liquid, wet-spun, and then stretched 3 times in the coagulation bath to obtain fibers with a fiber diameter of 15 μm. A nonwoven fabric having a basis weight of 6 g/m ² was prepared from the fibers.

The obtained fiber aggregate was subjected to the same operation as in Example 1 to obtain a catalyst-carrying fiber structure. The final catalyst activity evaluation results are shown in Table 1. The resulting fibrous structure lacked flexibility.

Example 3

A preparation containing 1 part by weight of polyvinyl chloride with a degree of polymerization of 1300, 4.5 parts by weight of N, N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., special grade), 4.5 parts by weight of tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd. , special grade) solution. Next, using the apparatus shown in FIG. 1, the solution was sprayed to the fibrous substance collecting electrode (5 in FIG. 1) for 60 minutes. The inner diameter of the nozzle (1 of FIG. 1 ) is 0.8 mm, the solution supply rate is 20 μl/min, the voltage is 12 kV, and the distance from the nozzle (1 of FIG. 1 ) to the fibrous substance collecting electrode (5 of FIG. 1 ) is 20 cm. The fiber structure obtained had a basis weight of 36 g/m ² and was in the form of a nonwoven fabric with a thickness of 0.2 mm. When the obtained fiber structure was observed with a scanning electron microscope (S-2400 manufactured by Hitachi, Ltd.), the average fiber diameter was 0.4 μm, and fibers with a fiber length of 20 μm or less were not observed. A scanning electron micrograph of the surface of the obtained fiber structure is shown in FIG. 8 .

Next, a photocatalyst coating agent ("PALTITAN 5607" manufactured by Nippon Parkerizing Co., Ltd.) was diluted with a methanol/isopropanol (1/1; weight ratio) mixed solvent to a catalyst concentration of 1% by weight to prepare a coating solution. The fibrous structure was coated with an air brush ("E1306" manufactured by KisoPower Tool Co., Ltd.: nozzle diameter: 0.4 mm) at a coating amount of 0.1 ml/cm ² to obtain a catalyst-carrying fibrous structure. The catalyst activity evaluation results are shown in Table 1.

Example 4

In Example 3, except that the spraying time of the solution was changed from 60 minutes to 15 minutes, the same operation was performed to form a nonwoven fabric-like fiber structure with a unit weight of 7.8 g/m ² and a thickness of 0.05 mm. .

When the obtained fiber structure was observed with a scanning electron microscope (S-2400 manufactured by Hitachi, Ltd.), the average fiber diameter was 0.3 μm, and fibers with a fiber length of 20 μm or less were not observed. A scanning electron micrograph of the surface of the obtained fiber structure is shown in FIG. 9 .

Next, the above-mentioned fiber structure was immersed in the coating solution prepared in Example 3 for 10 minutes, and then dried to obtain a catalyst-supporting fiber structure. The catalyst activity evaluation results are shown in Table 1.

Comparative example 2

A fabric (83 g/m ² per mesh) of polyvinyl chloride multifilament (single fiber diameter: about 17.54 μm) containing 84 dtex/25 monofilaments was immersed in the coating solution in the same manner as in Example 2 to obtain catalyst-supported fibers. structure. The catalyst activity evaluation results are shown in Table 1. The resulting nonwoven fabric lacked softness.

Example 5

A preparation containing 1 part by weight of polyvinyl chloride with a degree of polymerization of 1300, 4.5 parts by weight of tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd., special grade), 4.5 parts by weight of N, N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd. , special grade), 1.1 parts by weight of a solution of tetrabutoxytitanium (manufactured by Wako Pure Chemical Industries, Ltd., special grade). Using the apparatus shown in Fig. 2, the solution was sprayed toward the fibrous substance collecting electrode for 60 minutes. The inner diameter of the nozzle is 0.8mm, the voltage is 12kV, and the distance from the nozzle to the fibrous substance collecting electrode is 15cm.

The obtained fiber structure was put into an autoclave, kept in an aqueous solution of pH 3 at 80° C. for 17 hours, the sample was washed with ion-exchanged water, and dried to obtain a catalyst-loaded fiber structure with a weight of 32 g/cm ² . When the obtained catalyst-loaded fiber structure was observed with a scanning electron microscope (manufactured by Hitachi, Ltd. "S-2400"), the average fiber diameter was 0.5 μm, and fibers with a fiber length of 20 μm or less were not observed. In the X-ray diffraction results of the obtained catalyst-carrying fiber structure, a peak was observed at 2θ=25.3°, an anatase-type crystal of titanium oxide was formed, and a photocatalytic titanium oxide was formed from the catalyst precursor. Fig. 10 and Fig. 11 show scanning electron micrographs of the surface of the obtained catalyst-carrying fiber structure, and Fig. 12 shows the X-ray diffraction pattern, and Table 1 shows the catalyst activity evaluation results.

Comparative example 3

In embodiment 5, use the polyvinyl chloride that contains 1 weight part to be 1300 of degree of polymerization, 4.5 weight parts tetrahydrofuran (manufacture of Wako Pure Chemical Industry Co., Ltd., special grade), 4.5 weight parts N, N-dimethylformamide (wako pure Pharmaceutical Co., Ltd., special grade) solution, except that the same operation was performed to obtain a fiber structure with a density of 11 g/m ² . In the result of X-ray diffraction of the obtained fiber structure, no peak was seen at 2θ=25.3°. The X-ray diffraction pattern of the obtained fiber structure is shown in FIG. 13 , and the catalyst activity evaluation results are shown in Table 1.

Example 6

A porous membrane containing 1 part by weight of polyacrylonitrile (manufactured by Wako Pure Chemical Industries, Ltd.), 9 parts by weight of N,N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., reagent grade) and 1 part by weight of a catalyst was prepared. A solution of silica-coated titanium oxide ("MUSKMELON type photocatalyst" manufactured by Taihei Chemical Industry Co., Ltd., particle diameter: 2 µm). Next, using the apparatus shown in FIG. 1, the solution was sprayed to the fibrous substance collecting electrode (5 in FIG. 1) for 30 minutes. The inner diameter of the nozzle (1 of FIG. 1 ) is 0.8 mm, the solution supply rate is 20 μl/min, the voltage is 12 kV, and the distance from the nozzle (1 of FIG. 1 ) to the fibrous substance collecting electrode (5 of FIG. 1 ) is 15 cm. The basis weight of the obtained fibrous structure was 5 g/m ² . A scanning electron micrograph of the surface of the obtained fibrous structure is shown in Fig. 14. The average fiber diameter was 0.15 μm, and fibers with a fiber length of 20 μm or less were not observed. In addition, the particle diameter of the catalyst was 3 μm. Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 7

In Example 6, the same operation was carried out except that porous silica-coated titanium oxide ("MUSKMELON type photocatalyst" manufactured by Taihei Chemical Industry Co., Ltd., particle diameter: 5 μm) was used as a catalyst.

The fiber structure obtained had a mesh weight of 5 g/m ² , an average fiber diameter of 0.15 μm, no fibers with a fiber length of 20 μm or less were observed, and a catalyst particle diameter of 5 μm. A scanning electron micrograph of the fiber structure is shown in FIG. 15 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 8

In Example 6, the same operation was carried out except that porous silica-coated titanium oxide ("MUSKMELON type photocatalyst" manufactured by Taihei Chemical Industry Co., Ltd., particle diameter: 15 μm) was used as a catalyst.

The fiber structure obtained had a mesh weight of 5 g/m ² , an average fiber diameter of 0.15 μm, no fibers with a fiber length of 20 μm or less were observed, and a catalyst particle diameter of 13 μm. A scanning electron micrograph of the fiber structure is shown in FIG. 16 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 9

In Example 6, the same procedure was carried out except that titanium oxide coated with apatite ("Photocatalyst APATITE" manufactured by Taihei Chemical Industry Co., Ltd., particle size: 5 μm) was used instead of porous silica-coated titanium oxide as the catalyst. The fiber structure obtained had a mesh weight of 5 g/m ² , an average fiber diameter of 0.15 μm, no fibers with a fiber length of 20 μm or less were observed, and a catalyst particle size of 9 μm. A scanning electron micrograph of the fiber structure is shown in FIG. 17 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 10

In Example 6, the same operation was carried out except that titanium oxide ("PC-101A" manufactured by Titan Industry Co., Ltd., particle diameter: 40 nm) was used instead of porous silica-coated titanium oxide as the catalyst.

The fiber structure obtained had a mesh weight of 5 g/m ² , an average fiber diameter of 0.15 μm, no fibers with a fiber length of 20 μm or less were observed, and a catalyst particle diameter of 4 μm. A scanning electron micrograph of the fiber structure is shown in FIG. 18 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 11

Preparation containing 1 weight part of polyvinyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.), 4.5 parts by weight of N,N-dimethylformamide (manufactured by Wako Pure Chemical Industries, Ltd., special grade), 4.5 parts by weight of tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd. Kogyo Co., Ltd. product, special grade), and a solution of 0.5 parts by weight of porous silica-coated titanium oxide ("MUSKMELON type photocatalyst" manufactured by Taihei Chemical Industry Co., Ltd., particle diameter: 2 μm). Next, using the apparatus shown in FIG. 1, the solution was sprayed to the fibrous substance collecting electrode (5 in FIG. 1) for 30 minutes. The inner diameter of the nozzle (1 of FIG. 1 ) is 0.8 mm, the solution supply rate is 20 μl/min, the voltage is 12 kV, and the distance from the nozzle (1 of FIG. 1 ) to the fibrous substance collecting electrode (5 of FIG. 1 ) is 15 cm. The basis weight of the obtained fibrous structure was 7 g/m ² . When the surface of the resulting fibrous structure was observed with a scanning electron microscope, the average fiber diameter was 0.2 µm, and fibers with a fiber length of 20 µm or less were not observed. The catalyst particle size was 11 μm.

A scanning electron micrograph of the obtained fiber structure is shown in FIG. 19 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 12

In Example 11, the same procedure was carried out except that titanium oxide coated with apatite ("Photocatalyst APATITE" manufactured by Taihei Chemical Industry Co., Ltd., particle size 5 μm) was used instead of porous silica-coated titanium oxide as the catalyst. The fiber structure obtained had a weight of 7 g/m ² , an average fiber diameter of 0.2 μm, no fibers with a fiber length of 20 μm or less were observed, and a catalyst particle size of 10 μm. A scanning electron micrograph of the fiber structure is shown in FIG. 20 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Example 13

In Example 11, the same operation was carried out except that titanium oxide ("PC-101A" manufactured by Titan Industry Co., Ltd., particle diameter: 40 nm) was used instead of porous silica-coated titanium oxide as the catalyst.

The fiber structure obtained had a mesh weight of 7 g/m ² , an average fiber diameter of 0.2 μm, no fibers with a fiber length of 20 μm or less were observed, and a catalyst particle size of 9 μm. A scanning electron micrograph of the fiber structure is shown in FIG. 21 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Comparative example 4

In Example 6, the same operation was performed except that the porous silica-coated titanium oxide was not used. The fiber structure obtained had a basis weight of 5 g/m ² , an average fiber diameter of 0.15 μm, and no fibers with a fiber length of 20 μm or less were observed. A scanning electron micrograph of the fiber structure is shown in FIG. 22 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Comparative Example 5

In Example 11, the same operation was performed except that the porous silica-coated titanium oxide was not used. The fiber structure obtained had a basis weight of 7 g/m ² , an average fiber diameter of 0.2 μm, and no fibers with a fiber length of 20 μm or less were observed. A scanning electron micrograph of the fiber structure is shown in FIG. 23 . Table 1 shows the catalyst activity evaluation results of the obtained catalyst-carrying fiber structure.

Table 1

UV irradiation time (minutes) Absorbance at 665nm Example 1 30 0.07 Example 2 30 0.06 Example 3 30 0.08 Example 4 30 0.42 Example 5 60 0.37 Example 6 60 0.19 Example 7 60 0.20 Example 8 60 0.47 Example 9 60 0.27 Example 10 60 0.83 Example 11 60 0.13 Example 12 60 0.38 Example 13 60 0.93 10ppm methylene blue aqueous solution Not irradiated 1.80 Blank 30 1.06 Blank 60 1.16 Unsupported catalyst fiber structure 60 1.25 Comparative example 1 30 0.33 Comparative example 2 60 0.58 Comparative example 3 60 1.38 Comparative example 4 60 1.39 Comparative Example 5 60 1.40

Claims (11)

1. A method for preparing a catalyst-loaded fiber structure, the method comprising a step of dissolving a fibrous organic polymer to prepare a solution; a step of spinning the solution by electrospinning; A step of collecting the fibrous structure on the substrate; and a step of loading the catalyst on the fibrous structure. 2. The preparation method according to claim 1, wherein the solvent used for the above dissolution is a volatile organic solvent. 3. The production method according to claim 1, wherein the catalyst is supported by immersing the fibrous structure in a liquid containing the catalyst. 4. The production method according to claim 1, wherein the catalyst is supported by applying a catalyst-containing liquid on the surface of the fiber structure. 5. A method for preparing a catalyst-loaded fiber structure, the method comprising a step of dissolving a fibrous organic polymer and a catalyst precursor in a solvent to prepare a solution; a step of spinning the solution by electrospinning; The step of spinning to obtain a fiber structure accumulated on the collection substrate; and the step of treating the catalyst precursor contained in the fiber structure to form a catalyst. 6. The preparation method according to claim 5, wherein the solvent used for the dissolution is a volatile organic solvent. 7. The preparation method according to claim 5, wherein the method of treating said catalyst precursor is hydrothermal treatment. 8. A method for preparing a catalyst-loaded fiber structure, the method comprising dissolving a fibrous compound in a solvent to prepare a solution, and then dispersing catalyst particles therein to prepare a dispersion solution; the above dispersion solution is made by electrospinning the stage of spinning; and the stage of obtaining the catalyst-supporting fiber structure accumulated on the collection substrate by the above-mentioned spinning. 9. The method for producing a catalyst-carrying fibrous structure according to claim 8, wherein said catalyst particles are particles having a particle diameter in the range of 1 to 100 [mu]m. 10. The method for producing a catalyst-loaded fibrous structure according to claim 9, wherein said catalyst has a primary particle size of 1-100 [mu]m. 11. The preparation method according to claim 8, wherein the solvent used for the dissolution is a volatile organic solvent.

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