Photocatalytic body

The present invention relates to a photocatalyst that oxidizes an organic compound suspended in a gas or liquid (referred to as a fluid).

[0002] [Conventional Technology] The number of petrochemical products is increasing, and complex contamination of harmful organic compounds has become a problem inside and outside the living environment. As a means for solving this, there is a purification method using oxidative decomposition by a photocatalytic semiconductor.

[0003] For example, a method in which a photocatalytic semiconductor is supported on the surface of a gas constituting a device or equipment and the device or device is placed in a fluid in which a harmful organic substance is suspended to bring the harmful organic substance into contact with the photocatalytic semiconductor. is there. In this case, in order to exert the photocatalytic function at a high level, it is necessary that the surface area of the photocatalytic functional layer is large and that the photocatalytic semiconductor is sufficiently activated by electromagnetic waves having an excitation wavelength.

[0004] Therefore, various proposals have been made conventionally regarding a technique for increasing the surface area of a substrate and a film forming technique for forming a photocatalytic functional layer (see, for example, JP-A-5-309267 and JP-A-8-196903). ).

[0005] [Problems to be Solved by the Invention] However, even if the area of the photocatalyst functional layer is increased by simply increasing the surface area, the rate of activation by the electromagnetic wave of the excitation wavelength is low, or the fluid and the photocatalyst are activated. There are drawbacks such as poor contact efficiency with semiconductors. Further, in order to form an apparatus or an instrument, it is preferable that the substrate on which the photocatalytic semiconductor is supported has flexibility such that it can be formed by press working or can be rolled or bent. However, in particular, a substrate whose material is an inorganic material does not have such a condition, and the range in which a photocatalyst can be used is narrow.

[0006] Therefore, an object of the present invention is a photocatalyst that can increase the surface area of the substrate, activate the photocatalytic functional layer formed on the surface thereof almost uniformly, and increase the contact efficiency between the fluid and the photocatalytic semiconductor. To provide the body.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, a substrate having a plain weave wire mesh and a metal non-woven fabric fixed to the surface thereof, and a photocatalyst formed on the surface of the substrate. We adopted the technical means of having a functional layer.

[Embodiments of the Invention] The details of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a photocatalyst according to an embodiment of the present invention. In the figure, 1 is a photocatalyst, 2 is a substrate, 3 is a plain weave wire mesh, 4 is a metal non-woven fabric, and 5 is a photocatalyst functional layer. The cross section of the metal non-woven fabric is shown in Fig. 2.

[0009] The substrate 2 is a plain woven wire mesh 3 made of a metal material, and a metal wire or metal fiber having a diameter of 10 to 50 μm cut into a length of several mm to several tens of mm to be made into short fibers on the wire mesh. Spray so that the density ratio is, for example, 90%, and 5 to 50 g / cm for this.²(Alternatively, the area of the fiber intersection may be increased by rolling the short fibers before sintering), for example, in a hydrogen atmosphere (even in a vacuum) at 1000 to 1150 ° C for 30 minutes to 8 It has a metal non-woven fabric 4 formed by time sintering. Further, the metallic non-woven fabric may be rolled after sintering (rolling ratio 20 to 50%), whereby the mechanical strength can be improved. In the metal non-woven fabric, since the intersecting portions of the short fibers are sintered and fixed, a strong non-woven fabric can be obtained. Further, since the metal non-woven fabric is supported by the wire mesh, the substrate has high mechanical strength. As the above metal material, for example, any one selected from austenitic stainless steel, Al, Ti or Cu and an alloy thereof can be used. Cu is made of antibacterial material itself, Ti and stainless steel are excellent in rust prevention and durability, and aluminum alloy is rustproof and lightweight at the same time. The above-mentioned metal non-woven fabric has a thickness of 0.1 to 4 mm, has a fiber structure equivalent to that in the surface direction in the cross-sectional direction, and has an opening size in the surface direction larger than 10 μm. If the thickness of the metal non-woven fabric is too thick, the weight becomes large, while if it is too thin, the mechanical strength decreases. Therefore, it is desirable that the thickness is about 0.1 to 4 mm. Further, it is desirable that the opening of the metal non-woven fabric has a pore diameter of 50 to 1000 μm.

[0010] The photocatalyst functional layer 5 is, for example, TiO.₂A sol solution containing a photosensitive semiconductor such as the above can be formed by attaching it to the surface of a substrate by spraying or dipping, drying it, and then baking it at a temperature of 50 ° C to less than 500 ° C. If amorphous titanium peroxide or titanium oxide is mixed in the sol in a titanium weight ratio (dry amount) in the range of 1: 1 or 1: 5, the photocatalytic semiconductor can be mixed at a relatively low temperature. The particles can be firmly supported.

[0011] Furthermore, Pt, Ag, Rh, RuO for functional complementation such as antifungal sterilization.₂, Nb, Cu, Sn, NiO particles are mixed in a small amount, or zeolite, silica (silicon dioxide), alumina, zinc oxide, magnesium oxide, rutile type is added to improve the decomposition performance by redox. Inorganic materials such as titanium oxide and zirconium phosphate, various activated carbons, and porous phenol resins and melamine resins can be mixed in one or more.

[0012] Further, the photocatalyst functional layer can be formed after the surface of the substrate is sprayed with a protective material such as an aqueous solution of titanium peroxide to perform a base treatment for forming a protective film. In either case, if a film is formed in advance with PTA (oxysantinic titanium acid ...... titanium peroxide aqueous solution), TiO₂Adhesion and ductility of the sol solution are improved and it is easy to get wet, and a photo-touch functional layer can be uniformly and widely formed on the surface of the substrate. PTA has excellent ductility even when the substrate is a metal such as stainless steel, and TiO₂It is effective for applying the sol solution widely and evenly. PTA also functions as a binder, but it does not contain ceramics in composition and is compatible with metals, so the photocatalytic functional layer formed on the surface of the substrate peels off even if the substrate bends or vibrates. There are few things.

[0013] Other photocatalytic semiconductors include ZnO and SrTiO.₃, CdS, CdO, CaP, InP, In₂O₃, CaAs, BaTiO₃, K₂NbO₃, Fe₂O₃, Ta₂O₅, WO₃, SaO₂, Bi₂O₃, NiO, Cu₂O, SiC, SiO₂, MoS₂, MoS₃, InPb, RuO₂, CeO₂and so on. Among them, titanium oxide TiO₂(Anatase type) is inexpensive, has stable properties, is harmless to the human body, and is the best photocatalyst.

[0014] The catalytic function of a photocatalytic semiconductor is an excitation wavelength equal to or greater than the band gap of a semiconductor such as a metal oxide (electromagnetic wave of excitation wavelength, TiO).₂In the case of (ultraviolet region), electron cleavage occurs in the semiconductor by irradiating it, and OH- and O are generated on the surface.₂-Active radicals Hydroxyl groups and active oxygen are generated, and organic compounds in contact with them are decomposed by oxidation or reduction. As a result, foul odors and oil stains can be cleaned. In addition, the same function can kill bacteria and viruses (sterilization).

[0015] With the structure of the present invention, the surface area of the photocatalytic functional layer is large, and the electromagnetic wave of the excitation wavelength irradiated from the outside easily reaches the particles deep in the photocatalytic functional layer, so that the photocatalytic functional layer has a wide range. Is activated by. Further, since the fluid passing through such a laminated structure portion hits the wall of the laminated structure and is reflected, or enters a recess and temporarily stays there, there are many opportunities for organic substances suspended in the fluid to come into contact with the photocatalytic semiconductor. .. Therefore, the photocatalyst has high performance.

[0016] The photocatalyst body configured as described above can be used in various forms, but it may be used by forming photocatalyst functional layers on both sides of a single flat substrate. In this case, an electromagnetic wave source of excitation wavelength is arranged along both side edges of the flat plate, one surface (front) of the flat plate is irradiated with the electromagnetic wave supply source of one excitation wavelength, and the other electromagnetic wave source of electromagnetic waves of the other excitation wavelength It is possible to irradiate the front surface (back surface).

[0017] In the present invention, since the substrate has a large number of fine through holes, this photocatalyst can be used as various filters. Not only a filter as an element, but also, for example, when it is used as a filter for a gas that circulates in the refrigerator by forming an inner wall of the refrigerator that is sealed like a refrigerator, vegetables and fruits such as ethylene gas can be removed from the air in the refrigerator. It can remove harmful gases that are depleted, and can also remove unpleasant odors such as hydrogen sulfide and mercaptan. In this case, since the inner wall functions as a filter, the volume inside the refrigerator is not reduced and the filter does not get in the way as compared with the case where the filter is separately provided in the refrigerator.

[0018] Further, such a photocatalyst can have a sound deadening function, a visual shielding function, or a wave canceling or defoaming function when the fluid is in a liquid phase, as well as a cleaning function depending on the mode of use. Muffling is, for example, when a photocatalyst is used as a boundary wall plate that separates a roadway from a human road on a road. NOx and SOx are decomposed and removed by a photocatalyst functional layer, and at the same time, the substrate is made of a metal non-woven fabric. It guides sound waves into the complex internal space of a metal non-woven fabric and absorbs its propagating energy. The visual shielding function is a function of blocking the passage of light, which makes it possible to use the photocatalyst as a partition or the like. In addition, wave-dissipating is similar to absorbing sound waves. The wave motion of the liquid makes the contact opportunity between the organic compound suspended in the liquid and the photocatalytic semiconductor non-uniform, but the above-mentioned metal non-woven fabric temporarily stops the fluid in the internal space of the metal non-woven fabric, and the contact with the photocatalytic semiconductor. Contact opportunities are almost uniform.

[0019] In addition, the photocatalyst of the present invention can be used for the airframe or filter of an air conditioner or an exhaust gas treatment device, an indoor wall board for a toilet or a building, an algae-proof ornamental water tank wall, a swimming pool wall, or the like.

[Example] Example of photocatalyst production (Example 1) As a substrate, SUS fiber having a diameter of 20 μm and a length of 5 mm is sprayed on a plain weave wire mesh made of SUS316, and after sintering at 1100 ° C. for 5 hours. A metal non-woven fabric (thickness 0.2 mm, opening size in the surface direction 70 μm (mean value)) prepared by rolling (rolling ratio 50%) was used. FIG. 3 is a schematic view showing SUS fibers, and FIG. 4 is a schematic view showing SUS fibers rolled after sintering. From FIG. 4, it can be seen that the intersecting portions of the sintered SUS fibers are fixed to each other.

[0021] Next, as a photocatalytic functional material, an almofus-type titanium peroxide aqueous solution (0.84 w%): anatase-type titanium oxide aqueous solution (0.84 w%): colloidal silica aqueous solution (0.84 w%) at a ratio of 3: 7: 0.1. 0.7g / 25cm on the surface of the substrate after mixing²Spray (wet state). Then, after drying at room temperature, it was dried by heating (300 ° C × 1 hr) to obtain a photocatalyst.

(Example 2) As an adsorption / photocatalyst functional material, amorphous titanium peroxide aqueous solution (0.84%): anatase type titanium oxide aqueous solution (0.84%): colloidal silica aqueous solution (0.84%): coconut shell activated carbon (other aqueous solution). (Weight conversion) was mixed at a ratio of 3: 3: 0.1: 0.3 and 0.6 g / 25 cm on the surface of the substrate of Example 1.²Spray (wet state). Then, the whole was heated and dried (300 ° C × 1 hr) to obtain a photocatalyst.

FIG. 5 is a photocatalyst device 9 in which a photocatalyst body 1 formed on a flat plate is fitted in a frame 7 and a fluorescent lamp 8 as an electromagnetic wave supply source of an excitation wavelength is integrally incorporated. The photocatalyst 1 is shown in Example 1, and the frame 7 is made of stainless steel and is formed in a rectangular shape. The frame material constituting the vertical frames on both sides provides a space for accommodating the fluorescent lamp 8. Therefore, when the frame 7 is viewed from above, it becomes a long rectangle corresponding to the cross-sectional shape, and the flat plate photocatalyst 1 is arranged along the diagonal line thereof. With this structure, one surface (front side) of the photocatalyst body 1 is irradiated by one fluorescent lamp 8 and the other surface (back surface) is irradiated by the other fluorescent lamp 8, and the photocatalyst functional layer on each surface is activated. .. Ultraviolet rays from the fluorescent lamp 8 irradiate the surface of the photocatalyst 1 from one side, but the surface of the photocatalyst 1 is reflected by the uneven surface of the metal non-woven fabric, and ultraviolet rays are also emitted to the part that becomes a shadow when viewed from the fluorescent lamp side. Upon reaching it, the front surface of the photocatalyst functional layer on the surface of the photocatalyst is almost activated, and an efficient photocatalyst function is exhibited. Since this photocatalyst device 9 is breathable, it can be used not only as a filter but also as a partition that also serves as a room air purification device.

[0024] FIG. 6 shows a cross section of the low temperature storage chamber 10 for storing vegetables and the like. The low temperature storage chamber 10 is sealed by a door (not shown), but the flat photocatalyst 1 shown in Example 1 is attached to the inside of the box-shaped outer wall 11 in the form of a lining with an interval of 12. ing. A flat reflector 13 and fluorescent lamps 8 as an ultraviolet source are arranged on both sides of the flat reflector 13 in a diagonal arrangement at a space 12 of the ceiling portion. As shown in FIG. 7A, the flat plate type reflector 13 has reflection pieces 14 formed on both sides and reflects ultraviolet rays from the fluorescent lamps 8 on both sides in the same direction, that is, in the direction of the photocatalyst 1 on the ceiling. When the photocatalyst functional layer is present on both sides of the panel like the central partition wall, the reflector 13 having the reflection layer 18 on both sides is used as shown in FIG. 7 (b). The reflective layer 18 is composed of, for example, a laminate of SUS particles baked on both sides of a stainless steel plate 19. The particles are densely arranged with a small diameter on the 19th side of the steel sheet and coarsely arranged with a large diameter on the side away from the substrate. An elliptical curved reflector 16 having a mirror surface on the inside and a fluorescent lamp 8 as an ultraviolet source are arranged inside the center of the reflector 16 at intervals 15 of the wall portions. The spaces 13 and 15 are connected to ducts 17 on both sides of the ceiling, and the internal air of the storage chamber 10 is circulated through the photocatalyst 1 which is an inner wall by a circulation pump. Then, organic compounds that are inconvenient for storing vegetables such as ether and odor floating in the air when passing through the photocatalyst 1 are decomposed by oxidation / reduction action. When the substrate 2 has moldability as in the embodiment, the photocatalyst 1 as the inner wall is not formed by combining flat plates, but can be formed into a container shape at once by press working. If peeling of the photocatalyst functional layer becomes a problem, the photocatalyst functional layer may be formed after the substrate 2 is pressed.

[0025] FIG. 8 shows an example in which the photocatalyst 1 is used as a measure against deodorization of the toilet, and the photocatalyst 1 is attached to the ceiling as a flat plate at intervals. Reference numeral 8 is a fluorescent lamp, which is a source of ultraviolet rays. In the indoor space of a toilet, indoor air is normally flowing by a ventilation device at all times, and the suspended organic compound, which is the source of odor, collides with the photocatalyst 1 on the air flow and is decomposed by the photocatalyst functional layer. Since the surface of the photocatalyst 1 has an uneven laminated structure with voids, it is easily decomposed during contact with suspended organic compounds and passing through pores to easily receive a photocatalytic function, and the deodorizing effect is improved.

[Effectiveness of the Invention] According to the present invention, the photocatalyst body is provided with many voids and irregularities on the surface layer portion, the area of the photocatalyst functional layer is large, the oxidizing / reducing power is large, and the organic compound floats in the fluid. There are many opportunities for contact with the photocatalyst functional layer, and a photocatalyst with high performance can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a photocatalyst according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a cross section of a metal nonwoven fabric.

FIG. 3 is a schematic view showing SUS fibers.

FIG. 4 is a schematic view showing sintered SUS fibers.

FIG. 5 is a perspective view showing a flat photocatalyst device.

FIG. 6 is a front view showing a cut-out low-temperature storage.

7 (a) and 7 (b) are plan views showing an example of a reflector.

FIG. 8 is a front view schematically showing a form of use in a toilet.

[Description of code] 1 Photocatalyst, 2 Substrate, 3 Wire mesh, 4 Metallic non-woven fabric, 5 Photocatalyst functional layer