JP5958809B2 - Oxide carrier manufacturing method, oxide carrier manufacturing device, and photocatalytic filter manufacturing method - Google Patents

Description

The present invention relates to an oxide carrier production method, an oxide carrier production device , and a photocatalyst filter production method , and in particular, an oxide carrier production capable of obtaining a photocatalyst filter having both high photocatalytic activity and low pressure loss. The present invention relates to a method, an oxide carrier manufacturing apparatus , and a photocatalytic filter manufacturing method .

  Titanium oxide is chemically stable and has low toxicity. Furthermore, since it was reported that the oxidizing power generated by light absorption is effective for antifouling, deodorizing, air purification, water purification, antibacterial, etc., it has been used in a wide range of fields. Applications are expanding.

  In order to use titanium oxide as a photocatalyst, it is usually necessary to immobilize it with respect to the substrate by some method. As a method for immobilizing powdered titanium oxide, a method using a binder such as silica is known. However, in this method, a large amount of binder that does not wait for the photocatalytic functionality is present around the photocatalyst, so that the photocatalytic functionality is significantly reduced. On the other hand, in a method of applying a solution such as a sol-gel method, it is possible to immobilize the photocatalyst on the substrate surface without using a binder.

  In general, when a photocatalyst is used as a surface, the above-described immobilization method is very effective. However, when a titanium oxide photocatalyst is immobilized on a ceramic foam or glass fiber filter surface by a liquid phase method, a large amount of titanium oxide coating is required to improve the photocatalytic activity. However, in such a photocatalytic filter by applying a large amount of titanium oxide, when a gas to be treated is passed through the filter, a large pressure loss is generated. Therefore, conventionally, pressure loss is reduced by means such as using a very coarse ceramic foam.

  Many technical proposals have been made on photocatalytic filters. For example, in Patent Document 1 listed below, in order to provide a high-performance photocatalytic filter having high contact efficiency with a photocatalyst, excellent ultraviolet light permeability, and low pressure loss, the surface area can be maintained at a high level and 80 to 90 can be maintained. There is disclosed a photocatalytic filter using a porous ceramic body capable of ensuring a remarkably large void percentage and supporting a photocatalyst on the ceramic porous body.

Further, Patent Document 2, includes a strength to withstand the essential pressure loss as the air filter, and toxic gases quickly large amount of adsorption, to provide a photocatalyst carrying glass fiber cloth which can be decomposed and removed, 100 to 400 m ² A photocatalyst-supporting glass fiber cloth obtained by supporting a photocatalyst on the surface of a porous glass fiber cloth having a specific surface area of / g is disclosed.

Japanese Patent Application Laid-Open No. 2004-351381 “Photocatalytic Filter, Deodorizing Device and Water Treatment Device Using the Photocatalytic Filter” Japanese Patent Application Laid-Open No. 2004-2176 “Photocatalyst-supporting glass fiber cloth, manufacturing method thereof, and air filter device using the same”

  Conventionally, in order to reduce pressure loss in a photocatalytic filter coated with a large amount of titanium oxide necessary for obtaining high photocatalytic activity, a photocatalyst is supported, for example, by using a very coarse ceramic foam as described above. Focusing on the structure of the carrier itself, efforts have been made to select suitable materials and improve the structure. However, in these methods, it is necessary to use a carrier having a certain volume or area, which has been an obstacle to downsizing the photocatalytic device. Of course, a large amount of photocatalyst must also be used. These problems of the prior art are common to the techniques disclosed in the above patent documents.

  An object of the present invention is to solve these problems of the prior art, and without using a large amount of photocatalyst, a photocatalytic filter capable of achieving both high photocatalytic activity and low pressure loss, and a method for producing an oxide carrier capable of obtaining the same. An oxide carrier manufacturing apparatus and an oxide carrier are provided. A further object of the present invention is to provide a photocatalytic filter that does not increase the volume and area of the photocatalyst carrier due to a decrease in pressure loss, and therefore does not hinder downsizing of the photocatalytic device, and a photocatalytic filter that can be obtained. An oxide carrier manufacturing method, an oxide carrier manufacturing device, and an oxide carrier are provided.

  As a result of examining the above problems, the inventor of the present application contacts the vaporized metal alkoxide on the surface of the base material in which the diol is present, and forms an oxide precursor (metal dioleate) on the surface of the object by such a reaction. A method for generating titanium oxide on the surface of an object by heat-treating (pyrolysis) was devised, and it was conceived that the problem could be solved based on this method, and the present invention was completed. That is, the invention claimed in the present application, or at least the disclosed invention, as means for solving the above-described problems is as follows.

[1] A precursor formation process in which an oxide precursor formed by reacting a diol and a metal alkoxide is formed on the surface of the support, and a heat treatment in which the oxide precursor is heat-treated to generate an oxide on the surface of the support. Ri Do from the process, the precursor formation process, characterized in that with respect to the diol were pre-impregnated to the carrier, a process of contacting the metal alkoxide vaporized, oxide carrier production method .
[2] The oxide carrier manufacturing method according to [1], wherein the carrier is any one of a filter, alumina fiber, alumina cloth, or ceramic paper.
[3] The amount of the oxide in the oxide carrier is 0.2 wt% or more and 4.2 wt% or less, or 4.5 × 10 ⁻⁴ g / cm ³ or more and 9.5 × 10 ⁻³ g. The oxide carrier production method according to [1] or [2], wherein the oxide carrier is / cm ³ or less.

[4] The amount of the oxide in the oxide carrier is 1.0 wt% or more and 3.2 wt% or less, or 2.3 × 10 ^-3 g / cm ³ 7.0 × 10 ^-3 g / cm ³ The method for producing an oxide carrier according to [1] or [2], which is as follows.
  [5] The method for producing an oxide carrier according to any one of [1] to [4], wherein the oxide is generated as a precipitate on the support surface.
  [6] The metal species related to the metal alkoxide is any one of titanium, aluminum, zirconium, tin, zinc, magnesium, silicon or iron, according to any one of [1] to [5] An oxide carrier manufacturing method.
  [7] The oxide carrier manufacturing method according to any one of [1] to [5], wherein the metal alkoxide is titanium alkoxide, and the oxide is titanium oxide.

[8] A method for producing a photocatalytic filter, which is produced by the method for producing an oxide carrier according to [7].
  [9] The method for producing a photocatalytic filter according to [8], wherein the carrier is a product using a silica fiber filter or glass fiber.
  [10] Titanium oxide particles are present in the form of precipitates on the fiber surface of the filter, which is a carrier, and the increase in pressure loss of the filter is 20 Pa or less when suctioned and measured at a ventilation rate of 5 cm / s using a vacuum pump. The method for producing a photocatalytic filter according to [8] or [9], wherein a photocatalytic filter is obtained.
  [11] A product production method comprising obtaining a photocatalytic filter by the method according to any one of [8] to [10], and producing any one of the following products [P] using the photocatalytic filter.
[P] Deodorizing products, air purification products, water purification products, antibacterial products, antifouling products

[12] A vaporization chamber for vaporizing the metal alkoxide, an air supply pipe for sending the vaporized metal alkoxide from the vaporization chamber to the reaction vessel described later, a diol impregnated in the carrier and the vaporized metal alkoxide are reacted to form an oxide precursor. An apparatus for manufacturing an oxide carrier, comprising: a reaction vessel for generating metal dioleate on the surface of the single unit; and a thermostatic bath for maintaining the reaction vessel in a constant temperature state.
  [13] A method for producing an oxide carrier, comprising producing the oxide carrier using the apparatus for producing an oxide carrier according to [12].
  [14] A method for producing a photocatalytic filter, wherein the photocatalytic filter is produced using the apparatus for producing an oxide carrier according to [12].
  [15] An object in which a metal alkoxide vaporized is brought into contact with the surface of an object in the presence of a diol to form metal diolate on the object surface, and an oxide is generated on the object surface by heat-treating the metal diolate Surface modification method.

Since the oxide carrier production method, the oxide carrier production device , and the photocatalyst filter production method of the present invention are configured as described above, an extremely small amount of oxidation can be performed without using a large amount of photocatalyst. By using titanium, a photocatalytic filter having both high photocatalytic activity and low pressure loss can be obtained. That is, according to the present invention, it is a revolutionary photocatalyst that has high decomposition performance as a photocatalyst, and is superior in performance and durability to withstand repeated use more than before, and that does not hinder downsizing of the apparatus. A filter can be obtained.

  In addition, according to the present invention, it is not necessary to increase the volume and area of the photocatalyst carrier in order to reduce the pressure loss. Therefore, there is no problem in downsizing the photocatalyst device such as an air cleaner. Moreover, according to this invention, the said photocatalyst filter can be obtained with a simple and cheap manufacturing method.

The oxide carrier production method, the oxide carrier production device , and the photocatalyst filter production method of the present invention can be used not only for titanium oxide photocatalysts but also widely for metal oxides. It can be obtained similarly. In other words, according to the present invention, the surface is chemically treated with metal oxides in a wide range of industries and products such as catalysts and surface treatments by using a simple and inexpensive method and effectively using a very small amount of a raw metal compound. A surface modification technique to be modified can be provided.

It is a flowchart which shows the basic composition of the oxide carrier manufacturing method of this invention. It is a conceptual diagram which shows the basic composition of the apparatus for oxide carrier manufacture of this invention. It is explanatory drawing which shows the structure outline | summary of the photocatalyst filter preparation apparatus of an Example. It is explanatory drawing which shows the structure outline | summary of the photocatalytic activity measuring apparatus of an Example. It is a photograph of the SEM image of the photocatalyst filter synthesize | combined by CVD method. It is a photograph of the SEM image of the photocatalyst filter synthesize | combined by CVD method. It is an EDX spectrum of the photocatalyst filter synthesize | combined by CVD method ((b) EDX spectrum of the surface of a silica fiber, (c) EDX spectrum of a spherical particle). It is a graph which shows the XRD pattern of a photocatalyst filter. It is a graph which shows the XRD pattern of a titanium oxide precursor ((a) 150 degreeC drying, (b) 500 degreeC baking sample). It is a graph which shows the acetaldehyde decomposition | disassembly performance of the photocatalyst prepared by CVD method. It is a graph which shows the relationship between TEOT injection | pouring amount and a titanium oxide carrying amount. It is a graph which shows the relationship between a titanium oxide carrying amount and photocatalytic activity. It is a photograph of the SEM image of the spherical titanium oxide particle on the silica fiber of a photocatalyst filter. It is a graph which shows the photocatalytic activity of the titanium oxide prepared on various conditions. Reflection UV-Vis. It is a graph which shows a spectrum. It is a graph which shows the result of the continuous decomposition | disassembly test of acetaldehyde using a photocatalyst filter.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. P1 is a flowchart showing the basic configuration of the oxide carrier manufacturing method of the present invention. As shown in the figure, the present oxide carrier manufacturing method includes a precursor formation step S1 in which an oxide precursor 3 obtained by reacting a diol 1 and a metal alkoxide 2 is formed on the surface of a carrier 4, and an oxide precursor 3 The heat treatment step S2 in which the oxide 5 is formed on the surface of the support 4 by heat treatment.

  With this configuration, according to the present manufacturing method, the oxide precursor carrier 9 in which the oxide precursor 3 formed by reacting the diol 1 and the metal alkoxide 2 is formed on the surface of the carrier 4 in the precursor formation step S1. Then, the oxide precursor 3 is heat-treated in the heat treatment step S2, and the oxide carrier 10 in which the oxide 5 is formed on the surface of the carrier 4 is obtained. Note that two processes can be taken as the precursor formation process S1, which will be described later. In any case, in the present invention, the oxide precursor 3 (metal diolate) is once formed using the metal alkoxide 2 and the diol 1, and the target oxide 5 is obtained via this.

  As the carrier 4, for example, a suitably specified filter, alumina fiber, alumina cloth, borosilicate glass filter paper, other glass fibers, or ceramic paper can be used. In particular, in the present invention, the carrier 4 is a desirable carrier such as a silica fiber filter or a suitable filter, so that the amount of oxide 5 produced through the process of the present invention is very small. It is possible to produce an oxide carrier that hardly increases the pressure loss of the carrier.

  The precursor formation step S1 in the production method of the present invention can be a step of bringing the vaporized metal alkoxide 1 into contact with the diol 2 previously impregnated in the support 4. That is, in this case, a procedure for impregnating the carrier 4 with the diol 2 and a procedure for vaporizing the metal alkoxide 1 are prepared in advance, and the vaporized metal alkoxide 1 is sent to the carrier 4 impregnated with the diol 2. In this procedure, the metal alkoxide 1 comes into contact with the diol 2 and the reaction proceeds to form an oxide precursor 3 (metal diolate). In this step S1, the target precursor carrier 9 is obtained. .

The vaporization of the metal alkoxide 1 can be easily performed by heat treatment. The impregnation of the diol 2 into the carrier 4 (base material) can also be easily performed by applying the diol 2 to the surface of the base material. Further, the metal alkoxide 1 heated and vaporized may be sent to the substrate surface together with an appropriate carrier gas such as N ₂ . Further detailed conditions can be appropriately designed using known techniques.

  The oxide precursor 3 (metal diolate) generated on the surface of the base material (4) through the precursor formation step S1 is then heat-treated in air in the heat treatment step S2 to become the oxide 5. By this method, a very small amount of metal oxide 5 is generated on the surface of the base material, and a modified material (oxide support 10) is obtained thereby. It should be noted that the heat treatment step S2 can also be designed as appropriate using known techniques for more detailed conditions.

  As the precursor formation step S1, a method different from this may be used. That is, it is a method in which a mixed liquid in which the diol 2 and the metal alkoxide 1 are mixed is prepared and impregnated in the carrier 4. Although details will be described later in Examples, the target oxide precursor 10 can be obtained by forming the oxide precursor 3 by this method and subjecting it to the subsequent heat treatment step S2.

  Note that the metal oxide 5 to be obtained is generated as a fine-size precipitate attached on the surface of the support 4 regardless of which of the above methods is used as the precursor formation step S1. This will be further described later in Examples.

  In the production method of the present invention, as the metal species related to the metal alkoxide, at least for titanium, aluminum, zirconium, tin, zinc, magnesium, silicon or iron, metal diolate is generated by the combination of diols and metal oxidation by thermal decomposition thereof. It is confirmed that the product is well formed. However, the principle of the present invention is that “metal diolate (oxide precursor) generation on a support by metal alkoxide and diol and formation of metal oxide by its thermal decomposition” is only for some specified metal species. Rather, it is widely applicable. Therefore, the metal species range of the present invention is not limited to the above elements.

  Examples of diols that can be suitably used include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, and 1,3-butane. Diol, 1,2-pentanediol, 2-methyl-2,4-pentanediol and the like. It has been confirmed that these can be used well. Of course, the present invention is not limited to this, and other diols can also be used.

  In the production method of the present invention, the target oxide may be titanium oxide and the metal alkoxide may be titanium alkoxide. Examples of titanium alkoxides that can be suitably used include tetraethyl orthotitanate, titanium (IV) n-butoxide, titanium (IV) t-butoxide, titanium (IV) ethoxide, titanium (IV) i-propoxide, titanium. (IV) Isobutoxide, titanium (IV) isopropoxide and the like. It has been confirmed that these can be used well. Of course, the present invention is not limited to this, and other titanium alkoxides can also be used.

  By producing as described above, the oxide carrier 10 can be obtained as a photocatalytic filter in which a very small amount of titanium oxide is carried. As the carrier 4 according to the present invention, various types can be used as described above. However, as the carrier of the photocatalytic filter, a material using a glass fiber such as a silica fiber filter or a filter paper made of borosilicate glass is preferable. Can be used.

  According to the production method of the present invention, it is possible to obtain a photocatalytic filter that hardly causes an increase in pressure loss due to the support of titanium oxide. For example, as described in Examples, a photocatalytic filter is obtained in which the increase in the pressure loss of the filter when measured by suction with a ventilation rate of 5 cm / s using a vacuum pump remains at a very low value of 20 Pa or less, and further 10 Pa or less. be able to. According to the present invention, the titanium oxide photocatalyst particles are formed on the fiber surface of the filter as a carrier, and therefore the pressure loss hardly increases. Of course, it is needless to say that a photocatalyst with high performance can be obtained.

  Thus, although the photocatalytic filter obtained by the production method of the present invention is also within the scope of the present invention, it is a revolutionary material having both high photocatalytic activity and low pressure loss. It can be applied to products in various fields of photocatalyst application such as products for water, water purification products, antibacterial products, and antifouling products. These products are also within the scope of the present invention.

  FIG. P2 is a conceptual diagram showing a basic configuration of an apparatus for producing an oxide carrier according to the present invention. As shown in the figure, the apparatus 100 for producing an oxide carrier includes a vaporizing chamber 20 for vaporizing a metal alkoxide, an air supply pipe 30 for sending the vaporized metal alkoxide from the vaporizing chamber 20 to a reaction vessel 40, a diol impregnated in a carrier, The main configuration includes a reaction vessel 40 that reacts vaporized metal alkoxide to generate metal diolate, which is an oxide precursor, on the surface of a simple substance, and a thermostatic chamber 50 that maintains the reaction vessel 40 in a constant temperature state. To do.

  With this configuration, in the oxide carrier manufacturing apparatus 100 of the present invention, a support impregnated with a diol is prepared in the reaction vessel 40 maintained in a constant temperature state by the constant temperature bath 50, while a metal alkoxide is formed in the vaporization chamber 20. Vaporized to become vaporized metal alkoxide, and vaporized metal alkoxide is sent from the vaporization chamber 20 to the reaction vessel 40 through the gas feed tube 30, where the diol impregnated in the carrier reacts with the vaporized metal alkoxide to form an oxide precursor. Certain metal diolates are formed on the support surface.

  The oxide precursor carrier obtained by the apparatus 100 for producing an oxide carrier is taken out from the reaction vessel 40 and subjected to an appropriate drying treatment as necessary, followed by heat treatment under predetermined conditions. An oxide carrier is obtained. In addition, the oxide support manufactured using this apparatus is also within the scope of the present invention.

  As described above, the method of forming a metal diolate on the surface of the object by contacting the vaporized metal alkoxide on the surface of the object in the presence of the diol, and generating an oxide on the surface of the object by heat treating the metal diolate, It can be generalized as a new object surface modification method and is a principle that can be applied to various products and fields in the future.

<Example>
Examples of the present invention will be described below, but the present invention is not limited to these examples. In addition, it is set as description of an Example by stating the outline | summary of the research and development process for obtaining the photocatalyst filter which is one of the typical examples of this invention.
<1. Experimental method>
1.1 Production Method of Photocatalytic Filter Modification of the silica fiber filter with titanium oxide (that is, production of a photocatalytic filter) was performed by the following method.
1.1.1 Method of synthesizing photocatalytic filter by CVD method FIG. 1 is an explanatory diagram showing an outline of the configuration of a photocatalytic filter manufacturing apparatus according to the present embodiment. A glass reaction vessel was installed in the thermostatic chamber, and a vaporization chamber for heating and vaporizing N ₂ carrier gas preheating portion and tetraethyl orthotitanate (hereinafter “TEOT”) was provided at the top.

  A silica fiber filter (QR-100) manufactured by ADVANTEC (registered trademark) was cut into 75 mm × 75 mm and used as a substrate. The silica fiber was used after being baked at 500 ° C. for 2 hours in order to remove moisture and surface contamination. This silica fiber was immersed in 1,3-butanediol (hereinafter “13BD”) to absorb 13BD, and then placed in a glass reaction vessel. Furthermore, the glass reaction container was installed in the thermostat, and it connected with the vaporization chamber with the Teflon (trademark) tube.

  The thermostat and vaporization chamber were heated to 180 ° C., and nitrogen gas was circulated at a flow rate of 50 ml / min. Thereafter, 0.3 ml of TEOT was injected into the vaporizing chamber with a syringe. TEOT is vaporized in the vaporization chamber and led to the reaction tank in the thermostatic chamber together with nitrogen gas, and comes into contact with 13BD on the surface of the silica fiber filter to produce titanium diolate as a titanium oxide precursor. After the reaction, the silica fiber filter was taken out from the glass reaction vessel, dried in air at 150 ° C., and then heat treated in air at 500 ° C. for 2 hours to obtain a titanium oxide-modified silica fiber filter.

1.1.2 Synthesis of titanium oxide powder by sol-gel method (SGP method)
1 ml of TEOT was added to 10 ml of 13BD and stirred at room temperature for 30 minutes. Subsequently, the obtained solution containing the titanium oxide precursor was dried at 150 ° C. for 24 hours, and then fired at 500 ° C. for 2 hours to obtain a powder sample. Thus obtained powder sample (hereinafter referred to as “SGP method”) (0.1 g) was dispersed on a 75 mm × 75 mm silica fiber filter (QR-100) for evaluation of photocatalytic activity.

1.1.3 Production of Photocatalytic Filter (SGF Method) by Sol-Gel Method 1 ml of TEOT was added to 10 ml of 13BD, and stirred at room temperature for 30 minutes. 5 g of this solution was absorbed by a 75 mm × 75 mm silica fiber filter, dried at 150 ° C. for 2 h, and calcined at 500 ° C. for 2 h (hereinafter, this method is referred to as “SGF method”).

1.2 Evaluation of Titanium Oxide 1.2.1 Evaluation of Photocatalytic Activity 1.2.1.1 Evaluation of Photocatalytic Activity by Acetaldehyde Decomposition FIG. 2 is an explanatory diagram showing an outline of the configuration of the photocatalytic activity measuring apparatus of this example. is there. As shown in the figure, a 75 mm × 75 mm titanium oxide-modified silica fiber filter was placed in a 20 dm ³ glass desiccator. For the evaluation procedure, a sample was placed in a desiccator and then irradiated with ultraviolet rays (Toshiba Black Light, FL4BLB, peak wavelength 352 nm, ultraviolet intensity 4 mW / cm ² ) for 30 minutes. Next, after the inside of the desiccator was replaced with air, the temperature was adjusted to 25 ° C. and the humidity was adjusted to 13 g / m ³ . After 20 ppm of acetaldehyde was injected into the desiccator and the adsorption equilibrium was reached, ultraviolet irradiation was performed, and the change in concentration over time was analyzed with a photoacoustic multigas monitor model 1314 manufactured by INNOVA Air Tech Instruments. Since the decomposition of acetaldehyde is a first order reaction, the rate constant was calculated from the change in concentration.

1.2.1.2 Acetaldehyde continuous decomposition test In a desiccator of the photocatalytic activity measuring apparatus described in 1.2.1.1, a filter folder having a diameter of 4.5 cm was installed to fix the photocatalytic filter. An air pump was attached to the filtration folder, and the air in the desiccator was circulated at a ventilation speed of 5 cm / s. The procedure for evaluating the photocatalytic activity by decomposing acetaldehyde was the same as 1.2.1.1. However, when the concentration became 1 ppm or less, acetaldehyde was added again, and the decomposition reaction was repeated.

1.2.2 Powder X-ray diffraction (XRD) measurement In order to determine the crystal structure of titanium oxide and its precursor, Rigaku X-ray diffraction apparatus ULTIMA III type was used as the X-ray diffraction apparatus. A CuKα ray was used as the X-ray source, and measurement was performed at a tube voltage of 20 kV and 40 mA.

1.2.3 Observation by Scanning Electron Microscope (SEM) The surface shape of titanium oxide was observed using a scanning electron microscope S-4800 manufactured by Hitachi, Ltd.

1.2.4 Pressure loss evaluation method The titanium oxide-modified silica fiber filter was cut into a circular filter. This was fixed to a stainless steel filter folder (area: 15.9 cm ² ), sucked at a ventilation rate of 5 cm / s using a vacuum pump, and pressure loss was determined using a digital manometer.

<2. Results and Discussion>
2.1 Surface structure of photocatalytic filter FIG. 3 is a photograph of an SEM image of the photocatalytic filter synthesized by the CVD method. In a sample in which 2.0 mg of titanium oxide was supported on a 75 mm × 75 mm silica fiber filter, particle precipitation and adhesion of spherical particles could be confirmed on the silica fiber surface. These particles were subjected to elemental analysis by energy dispersive X-ray analysis (EDX).

  FIG. 4a is a photograph of an SEM image of a photocatalytic filter synthesized by a CVD method. FIG. 4bc is an EDX spectrum of a photocatalytic filter synthesized by a CVD method ((b) EDX spectrum of silica fiber surface, (c) EDX spectrum of spherical particles). As a result of elemental analysis, Ti was clearly detected from spherical particles adhering to the silica fiber surface as shown in (c). On the other hand, when elemental analysis was performed on the smooth portion of the silica fiber surface, the presence of Ti was confirmed in a small amount as shown in (b). From this, it was confirmed that a small amount of titanium oxide was generated (precipitated) on the silica fiber surface. In addition, it is considered that the spherical particles are part of 13BD impregnated in the silica fiber filter and are vaporized by heating, and contact with TEOT above the silica fiber filter to generate spherical particles, which are deposited on the filter.

2.2 Crystal Structure of Photocatalytic Filter FIG. 5 is a graph showing an XRD pattern of the photocatalytic filter, which is an XRD pattern of the photocatalytic filter in which the amount of titanium oxide supported is changed by changing the amount of TEOT injected into the vaporization chamber. CVD1, 2, and 3 have titanium oxide loadings of 3.9 mg, 6.2 mg, and 26.4 mg, respectively. In any sample, a peak of anatase-type titanium oxide was observed at around 2θ = 25.4 °. The broad peak around 2θ = 22 ° is a halo pattern derived from silica fibers. On the other hand, Degussa P-25 used for comparison was in a state where anatase type and rutile type were mixed. From the above results, it was confirmed that the titanium oxide formed on the silica fiber surface by the CVD method was anatase type titanium oxide.

  FIG. 6ab is a graph showing an XRD pattern of a titanium oxide precursor ((a) 150 ° C. dried, (b) 500 ° C. calcined sample), and 150 ° C. for samples prepared by the CVD method, SGP method, and SGF method, respectively. The result of having performed the XRD measurement about the sample dried by 500 degreeC and the sample after baking at 500 degreeC is shown. In the figure, in the sample dried at 150 ° C. shown in (a), 2θ = 10.1 ° and 8.4 ° specific to titanium geolate produced from TEOT and 13BD were recognized by any of the preparation methods. Moreover, in all the samples (b) obtained by firing these samples at 500 ° C., it was confirmed that anatase-type titanium oxide was produced. From the above results, it was clarified that anatase-type titanium oxide is produced by the production and thermal decomposition of titanium diolate even when prepared by the CVD method, as in the sol-gel method.

2.3 Photocatalytic activity evaluation FIG. 7 is a graph showing the acetaldehyde decomposition performance of a photocatalyst prepared by a CVD method. That is, the results of an acetaldehyde decomposition test under UV irradiation of a photocatalytic filter prepared by the CVD method are shown, and the sample is a photocatalytic filter carrying 6.2 mg of titanium oxide. 20 ppm of acetaldehyde was injected into a 20 dm ³ desiccator, the ultraviolet lamp was turned on, and the concentration change and carbon dioxide concentration were measured. As a result, the concentration of acetaldehyde rapidly decreased immediately after the start of ultraviolet irradiation, and decreased to 1 ppm or less in about 30 minutes. Moreover, since the carbon dioxide increased by about 40 ppm by decomposition | disassembly of acetaldehyde, it has confirmed that the oxidation reaction of acetaldehyde was progressing. Since decomposition of acetaldehyde proceeds by a first-order reaction, an index of catalytic activity is indicated by a rate constant of acetaldehyde decomposition.

2.4 Optimization of photocatalytic filter activity expression conditions by CVD method 2.4.1 TEOT injection amount and photocatalytic activity in the vaporization chamber on silica fiber (75 mm x 75 mm) by changing the amount of TEOT injected into the vaporization chamber The amount of titanium oxide supported was changed. At this time, the vaporization chamber was prepared at a temperature of 180 ° C., a thermostat temperature of 180 ° C., and a nitrogen gas flow rate of 50 ml / min. Table 1 shows the loading amount and the acetaldehyde decomposition rate constant when the TEOT amount was changed. As a result, the amount of titanium oxide supported on the silica fiber increased in proportion to the TEOT amount up to 0.7 ml of TEOT. In addition, the decomposition rate constant of acetaldehyde was maximized when the amount of supported titanium oxide was about 2 mg, and no increase in the photocatalytic activity (increase in the rate constant) due to an increase in the amount supported was observed when the amount supported was larger.

2.4.2 Effect of nitrogen gas flow rate on photocatalytic activity Changes in the photocatalytic activity were examined by changing the amount of nitrogen gas injected into the reactor through the preheater. At this time, the TEOT injection amount was 0.3 ml, the temperature of the vaporization chamber was 180 ° C., the thermostat temperature was 180 ° C., and the nitrogen gas flow rate was 50 to 200 ml / min. As shown in Table 2, as the nitrogen gas flow rate increases, the amount of titanium oxide supported and the acetaldehyde decomposition rate constant decrease, and in order to bring TEOT into contact with 13BD, the lower the flow rate of nitrogen as the carrier gas is better. It became clear.

2.4.3 Effect of temperature chamber temperature on photocatalytic activity TEOT injection volume 0.3ml, vaporization chamber temperature 180 ° C, nitrogen gas flow rate 50ml / min, temperature chamber temperature changed 130-180 ° C. The change in photocatalytic activity was measured. Table 3 shows the results. The TEOT vaporized in the vaporization chamber is led to the reaction vessel in the thermostatic chamber together with the nitrogen carrier gas. Therefore, the temperature of the thermostatic bath is substantially equal to the temperature of the reaction vessel. When the temperature of the thermostatic chamber was 150 ° C., the supported amount of titanium oxide was a maximum of 3.4 mg. However, the photocatalytic activity of the sample prepared at 180 ° C. was the highest.

2.4.4 Effect of vaporization chamber temperature on photocatalytic activity The TEOT injection amount is 0.3 ml, the nitrogen gas flow rate is 50 ml / min, and the vaporization chamber temperature is changed under the conditions of a constant temperature bath temperature of 180 ° C. Changes were measured. As shown in Table 4, when the vaporization chamber temperature was 150 ° C. or lower, titanium oxide was hardly supported on the silica fiber surface, and the photocatalytic activity was very low. On the other hand, at temperatures exceeding 150 ° C., 180 ° C. showed the highest photocatalytic activity.

2.4.5 Preparation of photocatalyst under optimum conditions From the results of 2.4.1 to 2.4.4, when the photocatalyst filter production apparatus as shown in FIG. 1 is used, the vaporization chamber temperature is 180 ° C. and the thermostat temperature is 180 °. It was revealed that the conditions for preparing the most active photocatalyst were at 0 ° C. and a nitrogen gas flow rate of 100 ml / min. Therefore, using such conditions, the TEOT injection amount was changed, and the relationship between the photocatalytic activity and the loading amount was examined.

  FIG. 8 is a graph showing the relationship between the TEOT injection amount and the titanium oxide loading. As shown in the figure, it was confirmed that the amount of supported titanium oxide increased in proportion to the TEOT amount.

  FIG. 9 is a graph showing the relationship between the amount of supported titanium oxide and the photocatalytic activity (acetaldehyde decomposition rate constant). As shown in the figure, the maximum activity was observed at a supported amount of 6 mg, and thereafter no increase in photocatalytic activity was observed even when the supported amount was increased.

  FIG. 10 is a photograph of an SEM image of spherical titanium oxide particles on the silica fiber of the photocatalytic filter, and the amount of titanium oxide supported is 20 mg. As shown in the figure, when the amount of titanium oxide supported increased, many spherical particles were confirmed on the surface of the silica fiber. This is presumably because TEOT and 13BD contacted not in the silica fiber surface but in the space above the silica fiber to form spherical particles and deposited on the silica fiber.

  Therefore, when the supported amount is very small, such as 6 mg or less, an extremely highly active titanium oxide is produced by a direct reaction of TEOT and 13BD on the surface of the silica fiber via a geolate as shown in the XRD diagram of FIG. 6ab. It is thought that it is generating. When the amount of titanium oxide supported is large, it is considered that a large number of spherical particles reacted in the gas phase are deposited on the silica fiber as described above. Spherical particles are considered to have a slightly lower photocatalytic activity than titanium oxide directly produced on silica fibers, and as a result, the photocatalytic activity was not so high despite the increased amount of titanium oxide supported. .

FIG. 11 is a graph showing the photocatalytic activity of titanium oxide prepared under various conditions. Photocatalytic filter supporting titanium oxide by CVD method, photocatalytic filter supporting titanium oxide by SGF method, filter in which titanium oxide powder is dispersed by SGP method, and filter in which P-25 made by Degussa (registered trademark) is dispersed Samples are shown, which show the relationship between the supported amount of titanium oxide and the photocatalytic activity represented by the acetaldehyde decomposition rate constant. A 56.3 cm ² silica fiber filter was used as the filter.

In the CVD method, a sample having a decomposition rate constant of about 0.1 min ⁻¹ was obtained with a very small amount of titanium oxide of 10 mg or less, and it became clear that the titanium oxide by the CVD method showed a high photocatalytic activity in a very small amount. . In addition, the SGF method using a procedure in which the same raw materials as in the CVD method are mixed in a solution and applied to a silica fiber filter also showed a very high photocatalytic activity as in the CVD method. However, in the SGF method, the photocatalytic activity was low when the loading was 10 mg or less compared with the CVD method. This is because the titanium geolate crystals are dispersed in 13BD in the raw material solution of the SGF method. For this reason, in particular in the case of a low loading amount, the uniformity of the loading on the silica fiber surface or the particles It is conceivable that the support density of the resin became low. Therefore, when using the SGF method, it was considered desirable to have a supported amount that is greater than the CVD method.

On the other hand, in the sample in which the powder sample was dispersed on the silica fiber filter, the photocatalytic activity was improved in proportion to the amount of titanium oxide supported in both the P-25 and SGP methods. However, in order to reach a decomposition rate constant of 0.1 min ⁻¹ as in the case of a CVD method sample, it is necessary to carry a large amount of titanium oxide of about 100 mg. Even in comparison with these, it was confirmed that the titanium oxide obtained by the CVD method exhibits a high photocatalytic activity even in a very small amount.

2.4.6 Reflection UV-Vis. Spectral CVD-prepared photocatalyst filter with 3.9 mg of titanium oxide supported and P-25, reflected UV-Vis. Measurements were made.
FIG. 12 shows the reflected UV-Vis. It is a graph which shows a spectrum. As shown in the figure, the absorption edge of the CVD method sample was slightly blue shifted from that of P-25. However, despite the small amount of 3.9 mg supported on a 75 mm × 75 mm filter, clear UV absorption was exhibited. Therefore, it was confirmed that the titanium oxide prepared by the CVD method was sufficiently excited by ultraviolet irradiation and could exhibit photocatalytic functionality.

2.5 Pressure loss of photocatalyst filter Table 5 shows the results of measuring the pressure loss of filters carrying the photocatalyst prepared by various methods. Here, the pressure loss was expressed as ΔP by an increase in the pressure loss due to the titanium oxide support, based on the silica fiber filter that is the titanium oxide support. In the photocatalytic filter prepared by the CVD method, the increase in pressure loss was slight due to the small amount of titanium oxide supported. Further, even in the SGF method in which mass loading is easy, ΔP has a small value when the loading amount is low. On the other hand, in the P-25 or SGP method carrying a powder sample, the increase in pressure loss due to titanium oxide loading was remarkable. From the above results, it has been clarified that the photocatalytic filter prepared by the CVD method not only exhibits high photocatalytic activity in a very small amount, but also hardly increases the pressure loss due to titanium oxide loading.

2.6 Continuous reaction of photocatalytic filter It was revealed that the photocatalytic filter by the CVD method exhibits low pressure loss and high photocatalytic activity. Therefore, a continuous decomposition test of acetaldehyde was carried out using a sample having a titanium oxide loading of 2 mg. In the measurement, a photocatalyst filter was fixed by installing a folder with a diameter of 45 mm in the apparatus shown in 1.2.1.1. An air pump was attached to the folder, and the air in the desiccator was circulated and circulated at a ventilation rate of 5 cm / s.

FIG. 13 is a graph showing the results of a continuous decomposition test of acetaldehyde using a photocatalytic filter, showing the results of repeating an experiment for decomposing 20 ppm of acetaldehyde four times. Since the area of the photocatalyst filter used in this decomposition test is 15.9 cm ^2, it is an ultraviolet irradiation area of about ¼ compared with the photocatalyst filter (56.3 cm ² ) that is normally used. Therefore, although it takes a long time to decompose acetaldehyde, it has the ability to decompose acetaldehyde to a low concentration of 1 ppm or less. In the repeated decomposition test, the first reaction showed a slightly high decomposition rate, but the second and subsequent reactions maintained almost the same decomposition rate, which is sufficient even when the gas to be treated is decomposed through a filter. It was confirmed that high photocatalytic activity could be maintained.

2.7 Effect of solvent on photocatalytic activity Table 6 shows the results of investigations on the effect of the solvent used in the preparation of the photocatalytic filter on the photocatalytic activity. The photocatalyst was prepared by impregnating each solvent into a 75 mm × 75 mm silica fiber filter at a vaporization chamber temperature of 180 ° C., a constant temperature bath temperature of 180 ° C., and a nitrogen gas flow rate of 100 ml / min to prepare a TEOT injection amount of 0.4 ml. The photocatalytic activity was shown as an acetaldehyde decomposition rate constant.

  As a result of the photocatalytic activity evaluation, among diols, diols having OH groups at 1,2- and 1,3-positions showed high activity. In particular, 1,3-propanediol and 1,3-butanediol showed high photocatalytic activity. All the diolates produced from diol having a high photocatalytic activity and TEOT have a diffraction pattern on the low angle side near 2θ = 10 ° in XRD measurement, and stable titanium diolates are produced. It was considered that this was rapidly decomposed in the course of baking at 500 ° C. and titanium oxide having a chemical state different from usual was generated.

  On the other hand, it is considered that a diol having an OH group at the 1,4- or 1,5-position cannot form a stable coordination bond with TEOT Ti because the distance between the OH groups is too large. It was. Also in alcohol, since it was monodentate with respect to Ti, the binding stability of diolate was low, and it showed almost no activity. Although water promotes the hydrolysis of TEOT, it was recognized that it does not contribute to the support of titanium oxide and the expression of photocatalytic activity. Further, in a system without using a solvent, titanium oxide showing almost no activity was produced. Thus, selection of the kind of solvent made to contact with TEOT is very important in the preparation of the photocatalytic filter, and it has become clear that 1,3-butanediol and 1,3-propanediol are most suitable.

2.8 Influence of Titanium Oxide Support In this example, for synthesis of titanium oxide by the CVD method, an ADVANTEC (registered trademark) QR-100 silica fiber filter is usually used as a base material. Titanium oxide was supported on a simple substrate by the CVD method, and the photocatalytic activity was evaluated. The sample preparation conditions were evaluated by changing the amount of TEOT at a vaporization chamber temperature of 180 ° C., a thermostatic bath temperature of 180 ° C., and a nitrogen gas flow rate of 100 ml / min. For the base material, Mitsubishi Plastics Co., Ltd. alumina fiber MAFTEC (registered trademark) (thickness 6 mm), alumina cloth (Tokyo glass instrument model AP1111 thickness 0.68 mm), ceramic paper (Tokyo glass instrument thickness 0.25 mm), And GA55 glass filter paper from ADVANTEC® was used. Table 7 shows the photocatalytic activity when titanium oxide is supported by the CVD method using these substrates. It was confirmed that any substrate can be used for the photocatalytic filter. It is known that the glass filter paper made of borosilicate glass has a reduced photocatalytic activity because sodium or the like migrates to the titanium oxide layer by heat treatment. However, according to the CVD method of the present invention, high photocatalytic activity was exhibited as in the case of using a silica fiber filter. In addition, other carriers had lower photocatalytic activity than when a silica fiber filter or glass filter paper was used as a substrate.

<Oxide loading in the present invention>
As described above, in the method for producing an oxide carrier according to the present invention, the amount of oxide produced is very small so that the increase in pressure loss of the carrier hardly occurs, and a sufficiently high photocatalytic activity can be obtained. .

The size of the silica fiber filter used in the above example is 75 mm × 75 mm × 0.38 mm (length × width × thickness), and the entire oxide support in a state where an oxide (titanium oxide) is supported thereon. The average weight was about 0.48 g. As shown in FIG. 9, in this example, the photocatalytic activity is saturated with a peak at about 10 mg of oxide supported. That is, the most preferable loading amount in the present invention is about 10 mg, and this corresponds to about 2 wt% in the weight ratio of the oxide carrier (base: 0.01 / 0.48 × 100 = 2.08 wt%). . Moreover, in volume ratio, it corresponds to the carrying amount of about 5 × 10 ⁻³ g / cm ³ (Evidence: 0.01 / (7.5 × 7.5 × 0.038) = 4.68 × 10 ⁻³ g / Cm ³ ).

On the other hand, especially in the CVD method, the expression of the photocatalytic activity is sufficiently recognized even at a loading amount of about 1 mg. If it is 5 mg or more, it is still good. On the other hand, in order to increase the pressure loss to 20 Pa or less, for example, the loading amount is desirably 20 mg or less, and more desirably 15 mg or less. From these numerical values, the respective weight ratios and volume ratios are as follows.
In the case of a loaded amount of 1 mg 0.001 / 0.48 × 100 = 0.21 wt%
0.001 / (7.5 × 7.5 × 0.038) = 4.68 × 10 ⁻⁴ g / cm ³
0.005 / 0.48 × 100 = 1.05wt% when loaded amount is 5mg
0.005 / (7.5 × 7.5 × 0.038) = 2.34 × 10 ⁻³ g / cm ³
0.015 / 0.48 × 100 = 3.15wt% when the loading amount is 15mg
0.015 / (7.5 × 7.5 × 0.038) = 7.02 × 10 ⁻³ g / cm ³
0.02 / 0.48 × 100 = 4.16wt% when the loading amount is 20mg
0.02 / (7.5 × 7.5 × 0.038) = 9.36 × 10 ⁻³ g / cm ³

From the above, the oxide loading recommended in the present invention can be summarized as follows.
A) Weight ratio is desirably 0.2 wt% or more and 4.2 wt% or less, and more desirably 1.0 wt% or more and 3.2 wt% or less. Furthermore, it is more desirable to set it as about 2 wt%.
B) Volume ratio: 4.5 × 10 ⁻⁴ g / cm ³ or more and 9.5 × 10 ⁻³ g / cm ³ or less is desirable 2.3 × 10 ⁻³ g / cm ³ or more and 7.0 × 10 ⁻³ It is more desirable to set it to g / cm ³ or less. Furthermore, it is more desirable to set 5 × ¹⁰ -3 g / cm ³ order.

According to the oxide carrier production method, the oxide carrier production device , and the photocatalyst filter production method of the present invention, high photocatalytic activity and low pressure loss can be achieved with a very small amount of titanium oxide without using a large amount of photocatalyst. It is possible to obtain an innovative photocatalytic filter having both of them, and it is also advantageous for downsizing a photocatalytic device such as an air cleaner. In addition to photocatalysts, the present invention is applicable not only to photocatalysts, but also to surface modification in a wide range of industrial and product fields, including catalysts and surface treatments, by effectively using a very small amount of raw metal compounds. It can be used as a technology. Therefore, the invention is highly applicable in this field and all related industrial fields.

DESCRIPTION OF SYMBOLS 1 ... Diol 2 ... Metal alkoxide 3 ... Oxide precursor 4 ... Carrier 5 ... Oxide 9 ... Oxide precursor support 10 ... Oxide support S1 ... Precursor formation process S2 ... Heat treatment process 20 ... Vaporization chamber 30 ... Air supply pipe 50 ... Constant temperature bath 40 ... Reaction vessel 100 ... Oxide carrier production apparatus

Claims (15)

A precursor formation process in which an oxide precursor formed by reacting a diol and a metal alkoxide is formed on the surface of the support; and a heat treatment process in which the oxide precursor is heat-treated to form an oxide on the surface of the support. Do Ri, precursor formation process, characterized in that with respect to the diol were pre-impregnated to the carrier, a process of contacting the metal alkoxide vaporized, the oxide carrier manufacturing method. The method for producing an oxide carrier according to claim 1, wherein the carrier is any one of a filter, alumina fiber, alumina cloth, or ceramic paper. The amount of the oxide in the oxide carrier is 0.2 wt% or more and 4.2 wt% or less, or 4.5 × 10 ⁻⁴ g / cm ³ or more and 9.5 × 10 ⁻³ g / cm ^3. The method for producing an oxide carrier according to claim 1 or 2 , wherein: The amount of the oxide in the oxide carrier is 1.0 wt% or more and 3.2 wt% or less, or 2.3 × 10 ⁻³ g / cm ³ or more and 7.0 × 10 ⁻³ g / cm ^3. The method for producing an oxide carrier according to claim 1 or 2 , wherein: The method for producing an oxide carrier according to any one of claims 1 to 4, wherein the oxide is generated as a precipitate on the support surface. Wherein the metal species of the metal alkoxide is either titanium, aluminum, zirconium, tin, zinc, magnesium, silicon or iron, oxide carrier preparation according to any one of claims 1 to 5 Method. The metal alkoxide is titanium alkoxide, wherein the oxide is titanium oxide, the oxide carrier manufacturing method according to any one of claims 1 to 5. Characterized in that to produce the oxide carrier manufacturing method according to claim 7, the photocatalytic filter manufacturing method. 9. The photocatalytic filter manufacturing method according to claim 8 , wherein the carrier is a product using a silica fiber filter or glass fiber. A photocatalytic filter in which titanium oxide particles are present in the form of precipitates on the fiber surface of a filter that is a carrier, and the increase in pressure loss of the filter is 20 Pa or less when suctioned and measured at a ventilation rate of 5 cm / s using a vacuum pump. The method for producing a photocatalytic filter according to claim 8 or 9 , wherein the photocatalytic filter is obtained. A photocatalytic filter is obtained by the method according to any one of claims 8 to 10 , and any one of the products shown in the following [P] is produced using the photocatalytic filter .
[P] Deodorizing products, air purification products, water purification products, antibacterial products, antifouling products A vaporizing chamber for vaporizing the metal alkoxide, an air feed pipe for sending the vaporized metal alkoxide from the vaporization chamber to the reaction vessel described later, a diol impregnated in the carrier and the vaporized metal alkoxide are reacted to form a metal diolate as an oxide precursor. An apparatus for producing an oxide carrier, comprising: a reaction vessel that is generated on the surface of the simple substance; and a thermostatic bath that maintains the reaction vessel in a constant temperature state. The oxide carrier manufacturing method which manufactures an oxide carrier using the apparatus for oxide carrier manufacture of Claim 12 . The photocatalyst filter manufacturing method which manufactures a photocatalyst filter using the apparatus for oxide support body manufacture of Claim 12 . Object surface modification in which vaporized metal alkoxide is brought into contact with the surface of an object in the presence of a diol to form metal diolate on the object surface and heat treatment of the metal diolate generates oxide on the object surface Method.