JP5604197B2 - Cerium oxide catalyst support for VOC decomposition - Google Patents

Description

  The present invention relates to a catalyst carrier in which the type of substrate is not limited and the catalyst fine particles are firmly fixed on the substrate. For example, a cerium oxide catalyst is used with a filter used for exhaust gas treatment in automobiles or factories as a substrate. The present invention relates to a cerium oxide catalyst carrier capable of efficiently decomposing a harmful gas such as VOC.

  Suspended Particulate Matter (SPM) contained in dust and exhaust gas, and photochemical smog generated by increasing the concentration of photochemical oxidant in the atmosphere have been a problem in recent years as affecting the global environment and human body. It has become. As a causative substance of SPM and photochemical smog, there is a volatile organic compound (VOC). Regarding VOC, the Air Pollution Control Act was revised in May 2004 to set a target value for VOC emission control, and it has been in effect since April 2006.

  As a method for removing VOC in such exhaust gas, a noble metal catalyst such as a Pt catalyst or a Pd catalyst is generally used.

  However, the VOC removal method using a noble metal catalyst has the following problems.

  When noble metal catalysts such as Pt catalyst and Pd catalyst are used, physical poisoning such as adsorption of dust, soot, and tar on noble metal catalyst during use, and chemical such as adsorption of chlorine compounds, sulfur compounds, and organosilicones. There is a problem that catalyst performance deteriorates due to poisoning.

  In addition, as mentioned above, due to the recent increase in environmental awareness, precious metal catalysts are used for purification of harmful gases and fuel cells, and the price of precious metals has risen due to the fact that they are rare metals, resulting in high costs. There is a problem.

Here, in recent years, cerium oxide (CeO ₂ ) alone, which is a component of a catalyst carrier for exhaust gas purification of a gasoline vehicle, has an oxygen storage / release capability of releasing oxygen in a reducing atmosphere and storing oxygen in an oxidizing atmosphere. However, it is reported to be effective in removing VOCs and decomposing soluble organic matter (SOF) such as unburned fuel and lubricating oil contained in the exhaust gas of gasoline vehicles (for example, Non-Patent Document 1, Non-Patent Document 2 and Patent Document 1). From this fact, a VOC removal method using a cerium oxide catalyst powder has also been studied (for example, Patent Document 2 and Patent Document 3). Further, a cerium oxide particle catalyst having a particle size of 30 to 200 nm supported on an HC adsorbent layer has been proposed (for example, Patent Document 4).

JP-A-8-290057 JP 2006-15338 A JP 2007-175612 A JP-A-9-927

D. Haffad, A. Chambellan, J.C. Lavall. Journal of Molecular Catalysis A: Chemical 168 (2001) p153-164 Ching-Huei Wang, Shiow-Shyung Lin. Applied Catalysis A: General 268 (2004) p227-233

  However, the cerium oxide catalyst fine particles are inorganic, and a sintering method is used to fix the fine particles to the substrate. As the material of the substrate, a honeycomb structure made of a material such as ceramic or metal that can withstand sintering, Limited to large granules. In addition, when applied to a filter or the like, there is a problem that the shape to be used is limited. In addition, a method using a binder or the like is also conceivable as a method for immobilizing on the substrate, but most of the used cerium oxide catalyst fine particles are embedded in the binder, and there are few fine particles exposed and functioning on the surface. The effect cannot be expected.

  Patent Document 4 discloses a cerium oxide particle catalyst having a particle size of 30 to 200 nm supported on an HC adsorbent layer. However, in Patent Document 4, cerium oxide is merely used as an auxiliary catalyst for a main catalyst such as palladium oxide or platinum oxide, and is not used as a single main catalyst. Therefore, the problem of using expensive noble metals still remains.

  Accordingly, the present invention has been made to solve such a conventional problem, and the cerium oxide catalyst fine particles can be firmly fixed to a substrate surface of any material and shape at a low temperature. An object of the present invention is to provide a cerium oxide catalyst carrier that efficiently expresses its function in shape and environment.

That is, the present invention is a cerium oxide in which the surface of each substrate is coated with a silane monomer, fixed to the surface of the substrate through a chemical bond between the silane monomer and the substrate surface, and bonded to each other through the chemical bond of the silane monomer. A cerium oxide catalyst carrier for VOC decomposition having catalyst fine particles.

Further, the present invention provides an inorganic fine particle, the surface of which is coated with a silane monomer, each of which is fixed to the surface of the substrate via a chemical bond between the silane monomer and the substrate surface, and bonded to each other by the chemical bond of the silane monomer. And a cerium oxide catalyst carrier for VOC decomposition having cerium oxide catalyst fine particles dispersed in a group of inorganic fine particles bonded to each other.

  According to the present invention, since the cerium oxide catalyst fine particles are fixed to the substrate through a chemical bond between the silane monomer and the substrate surface, the fine particles can be fixed at a low temperature. As a result, it is possible to provide a cerium oxide catalyst carrier that efficiently exhibits functions in various shapes and environments, using not only a substrate containing an inorganic material such as metal or ceramic but also a member containing an organic material as a substrate.

It is a schematic diagram of the cerium oxide catalyst support body of 1st Embodiment of this invention. It is a schematic diagram of the cerium oxide catalyst support body of 2nd Embodiment of this invention. It is a schematic diagram of the cerium oxide catalyst support body of 3rd Embodiment of this invention.

  Hereinafter, the cerium oxide catalyst carrier of the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a view schematically showing a part of a cross section of a cerium oxide catalyst carrier 100 according to the first embodiment of the present invention. The cerium oxide catalyst carrier 100 of the first embodiment is a catalyst carrier that removes VOC. The cerium oxide catalyst carrier 100 according to the first embodiment includes a substrate 1, inorganic fine particles 2-a, cerium oxide catalyst fine particles 2-b exhibiting catalytic performance, and a silane monomer 3.

  In FIG. 1, in order to schematically illustrate the first embodiment, the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b are different inorganic compounds, but FIG. As a second embodiment of the present invention, the case where the inorganic fine particles 2-a are not used, that is, the case where all the inorganic fine particles are cerium oxide catalyst fine particles 2-b is shown. Further, in FIG. 3, as a third embodiment of the present invention, the inorganic fine particles 2-a having the silane monomer 3 bonded to the surface are bonded to each other by a chemical bond of the silane monomer, and the surface of the substrate 1 is chemically In this example, the bond 4 is fixed by forming (covalent bond), and the cerium oxide catalyst fine particles 2-b are dispersed and fixed in the group of the inorganic fine particles 2-a bonded to each other.

  The silane monomer 3 has an unsaturated bond portion or a reactive functional group on the surface of the inorganic fine particle 2-a of the first or third embodiment of the present invention or the cerium oxide catalyst fine particle 2-b of the first or second embodiment. Oriented and bonded to the outside. Each of the inorganic fine particles 2-a or the cerium oxide catalyst fine particles 2-b is bonded to each other by a chemical bond 4 (covalent bond) obtained by a dehydration condensation reaction between the silane monomers 3.

  In addition, the base 1 and the inorganic fine particles 2-a or the cerium oxide catalyst fine particles 2-b are formed by forming a chemical bond 4 (covalent bond) between the silane monomer 3 on the surface of each fine particle and the surface of the base 1, Combined and fixed.

  The substrate 1 used for the cerium oxide catalyst carrier 100 in each embodiment of the present invention is not particularly limited as long as it is a material capable of chemical bonding 4 by the silane monomer 3, for example, various resins, Examples thereof include synthetic fibers, natural fibers such as cotton, hemp, and silk, carbon fibers, metal materials, and inorganic materials such as glass and ceramics.

  Here, examples of the resin used for the substrate 1 include polyethylene resin, polypropylene resin, polystyrene resin, ABS resin, AS resin, EVA resin, polymethylpentene resin, polyvinyl chloride resin, Polyvinylidene chloride resin, polymethyl acrylate resin, polyvinyl acetate resin, polyamide resin, polyimide resin, polycarbonate resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyacetal resin, polyarylate resin, , Polysulfone resin, polyvinylidene fluoride resin, thermoplastic resin such as ETFE and PTFE, polylactic acid resin, polyhydroxybutyrate resin, modified starch resin, polycaprolacto resin, polybutylene succinate resin And poly butyre Biodegradable resins such as adipate terephthalate resin, polybutylene succinate terephthalate resin, polyethylene succinate resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, epoxy resin Thermosetting resins such as epoxy acrylate resins, silicon resins, acrylic urethane resins, urethane resins, silicone resins, polystyrene elastomers, polyethylene elastomers, polypropylene elastomers, polyurethane elastomers, and lacquers And natural resins.

  Heat is required to remove VOC by the oxidation catalyst function of the cerium oxide catalyst fine particles 2-b. Although the heat required for the cerium oxide catalyst fine particles to promote oxidative decomposition varies depending on the VOC to be removed, the ambient temperature may require 50 ° C. or higher. For example, when the cerium oxide catalyst carrier 100 of the present embodiment is used for a filter for removing a VOC discharged from a factory, the surface of the catalyst on which the reaction is performed may be locally 100 ° C. or higher. Therefore, the substrate 1 is preferably made of a material having a melting point (heat resistance) higher than the temperature necessary for removing the VOC. Examples of the heat-resistant resin used in the substrate 1 include engineer plastics such as polyamide, polyacetal, polycarbonate polyphenylene ether, polybutylene terephthalate, glass fiber reinforced polyethylene terephthalate, and ultrahigh molecular weight polyethylene, polysulfone, polyethersulfone, Super engineering plastics such as polyphenylene sulfide polyarylate, polyamideimide, polyetherimide, polyetheretherketone, polyimide, fluorine resin such as ETFE and PTFE, and heat-resistant thermosetting resins such as polyphenol, melamine resin, and epoxy resin are preferable. .

  The inorganic material used for the substrate 1 of the cerium oxide catalyst carrier 100 of each embodiment of the present invention is not particularly limited as long as the silane monomer 3 is a material capable of chemical bonding 4 (covalent bonding) by dehydration condensation reaction. An oxide thin film is preferably formed on the surface of a material such as metal and ceramic.

  Examples of the metal material used for the substrate 1 include refractory metals such as tungsten, molybdenum, tantalum, niobium, TZM, and W-Re, noble metals such as silver and ruthenium, and alloys thereof, titanium, nickel, zirconium, chromium, and Inconel. Special metals such as Hastelloy, aluminum and its alloys, copper and its alloys and their alloys, stainless steel, zinc and its alloys, magnesium and its alloys, iron and their alloys, and various plating and vacuum deposition It is possible to use a metal material processed by a CVD method or a sputtering method.

  When the substrate 1 of each embodiment of the present invention is a metal or an alloy thereof, the surface of the inorganic fine particle 2-has been formed with an oxide thin film on which the coupling agent is covalently bonded by a dehydration condensation reaction. This is particularly necessary for firmly fixing a to the surface of the substrate 1. A natural oxide thin film is usually formed on the surface of the metal and the alloy thereof. In order to use this oxide thin film, it is preferable to remove the oil and dirt adhering by a known method in advance in order to fix the inorganic fine particles 2-a stably and uniformly. . Furthermore, an oxide thin film may be formed chemically by a known method, or an oxide thin film may be formed by a known electrochemical method such as anodic oxidation.

  Furthermore, ceramics such as earthenware, earthenware, plaster, magnetism, ceramics such as glass, cement, gypsum, enamel, and fine ceramics can be used for the substrate 1 of each embodiment of the present invention. The composition of the ceramics constituting the substrate 1 of the present embodiment includes ceramics such as elemental, oxide, hydroxide, carbide, carbonate, nitride, halide, and phosphate. They can also be used, or a composite thereof.

  The substrate 1 of each embodiment of the present invention includes soda lime glass, potash glass, crystal glass, quartz glass, chalcogen glass, organic glass, uranium glass, acrylic glass, water glass, polarizing glass, tempered glass, laminated glass, Glasses such as heat-resistant glass, borosilicate glass, bulletproof glass, glass fiber, dichroic, gold stone (brown stone, sand gold stone, purple gold stone), glass ceramics, low melting glass, metallic glass, and saphiret can be used. .

  In addition, the base 1 of each embodiment of the present invention includes ordinary Portland cement, early-strength Portland cement, ultra-high-strength Portland cement, medium heat Portland cement, low heat Portland cement, sulfate-resistant Portland cement, and Portland cement with blast furnace slag. It is possible to use cement such as fly ash, blast furnace cement, silica cement, and fly ash cement, which is a mixed cement to which a siliceous mixed material is added.

  The substrate 1 of each embodiment of the present invention includes barium titanate, lead zirconate titanate, ferrite, alumina, forsterite, zirconia, zircon, mullite, steatite, cordierite, aluminum nitride, silicon nitride, Ceramics such as silicon carbide, new carbon, new glass, high strength ceramics, functional ceramics, superconducting ceramics, nonlinear optical ceramics, antibacterial ceramics, biodegradable ceramics, and bioceramics can be used.

  In addition, in order to efficiently remove the cerium oxide catalyst carrier VOC, a method of supplying heat to the cerium oxide catalyst carrier 100 is important. When the general duct heater surrounds the catalyst filter layer composed of the cerium oxide catalyst carrier 100, there is a problem of uniform heat supply and control, and further downsizing of the apparatus can be achieved. difficult. However, by including a material having a performance as a heating element in the base 1, uniform heat supply can be achieved, and the apparatus can be made compact by integrating the heat source and the filter.

  The material contained in the substrate 1 is not particularly limited as long as it is a material having a performance as a heating element, but in the case of a metal material, an Fe—Cr—Al alloy, a Ni—Cr alloy Platinum, molybdenum, tantalum, and tungsten are preferable, and silicon carbide, molybdenum-silicite, carbon, graphite, zirconia, and lanthanum chromite are preferable when they are non-metallic materials. Moreover, as long as the material which has the said performance as a heat generating body is included, a combination with other materials, such as an insulating material, may be sufficient, and a structure is not limited.

  In each embodiment of the present invention, the shape of the substrate 1 may be various shapes and sizes suitable for the purpose of use, such as a punching sheet shape, a fiber shape, a cloth shape, a mesh shape, and a honeycomb shape.

  As described above, the silane monomer 3 is unsaturated on the surface of the inorganic fine particle 2-a of the first or third embodiment of the present invention or the cerium oxide catalyst fine particle 2-b of the first or second embodiment of the present invention. The bonding portion or reactive functional group is oriented and bonded outward.

  Here, the reason why the silane monomer 3 aligns and bonds the unsaturated bond portion or the reactive functional group toward the outside of the inorganic fine particle 2-a will be described in detail. This is because the silanol group at one end of the silane monomer 3 is hydrophilic, so that it is easily attracted to the surface of the inorganic fine particle 2-a, which is also hydrophilic, while the unsaturated bond portion or reactive functional group at the reverse end. This is because the group is hydrophobic and tends to be separated from the surface of the inorganic fine particle 2-a. For this reason, since the silanol group of the silane monomer 3 is covalently bonded to the surface of the inorganic fine particle 2-a by a dehydration condensation reaction, the silane monomer 3 is easily oriented with the unsaturated bond portion or the reactive functional group facing outward. Therefore, many silane monomers 3 are covalently bonded to the inorganic fine particles 2-a with the unsaturated bond portion or the reactive functional group facing outward.

  The unsaturated bond part or reactive functional group of the silane monomer 3 covalently bonded to the inorganic fine particles 2-a or the cerium oxide catalyst fine particles 2-b by dehydration condensation includes vinyl group, epoxy group, styryl group, methacrylo group, acryloxy Groups and isocyanate groups.

  Examples of the silane monomer 3 used in the cerium oxide catalyst carrier 100 of each embodiment of the present invention include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, N-β- (N-vinylbenzylaminoethyl). ) -Γ-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycol Sidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltri Methoxysilane, 3 -Methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and the like.

As the inorganic fine particles 2-a used in the cerium oxide catalyst support 100 of the first or third embodiment of the present invention, inorganic oxides such as non-metal oxides, metal oxides, and metal composite oxides are preferably used. The inorganic fine particles 2-a may be either amorphous or crystalline. Examples of the non-metal oxide include silicon oxide. Metal oxides include magnesium oxide, barium oxide, barium peroxide, gibbsite, boehmite, die spore, aluminum oxide, tin oxide, titanium oxide, zinc oxide, titanium peroxide, zirconium oxide, iron oxide, iron hydroxide, oxidation Examples include tungsten, bismuth oxide, indium oxide, antimony oxide, cobalt oxide, niobium oxide, manganese oxide, nickel oxide, cerium oxide, yttrium oxide, and praseodymium oxide. Examples of the metal composite oxide include titanium barium oxide, cobalt aluminum oxide, lead zirconium oxide, lead niobium oxide, TiO ₂ —WO ₃ , AlO ₃ —SiO ₂ , WO ₃ —ZrO ₂ , WO ₃ —SnO ₂ , and CeO. _2- ZrO ₂ , In—Sn, Sb—Sn, Sb—Zn, In—Sn—Zn, and the like can be given. These inorganic fine particles may be used alone or in combination of two or more.

  The inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b of each embodiment of the present invention preferably have an average particle size of 500 nm or less. When the average particle diameter is larger than 500 nm, the adhesion of the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b to the substrate 1 is lowered. For this reason, since the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b are more likely to be peeled than when the average particle diameter is 500 nm or less, maintenance work and costs are increased. Moreover, peeling of the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b may occur depending on the use environment, use time, and the like.

  Further, it is generally known that cerium oxide catalyst fine particles have higher catalyst performance as the particle diameter is smaller. There is a limit to the amount of catalyst fine particles that can be supported on the fiber structure, and from the viewpoint of cost, it is better that the amount of catalyst fine particles supported is small. By converting the cerium oxide catalyst fine particles 2-b into nanoparticles, It is possible to produce a filter that can exhibit catalytic performance in a small amount. However, reducing the particle size requires manufacturing time and manufacturing cost.

  Therefore, considering the relationship between the particle size and the catalyst performance, the average particle size of the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b is more preferably 300 nm or less, but most preferably the average particle size is 10 nm or more. 100 nm or less.

Moreover, in the cerium oxide catalyst carrier of each embodiment of the present invention, the cerium oxide catalyst fine particles having a high specific surface area are expected to have higher catalytic activity because the contact area in contact with the gas is increased. The specific surface area of the cerium oxide catalyst fine particles is preferably 20 m ² / g or more.

  In addition, one or more kinds of noble metal catalyst fine particles such as Ru, Rh, Pd, Ag, Ir, Pt, and Au may be supported on the cerium oxide catalyst fine particles 2-b or the inorganic fine particles 2-a of each embodiment of the present invention. . When one or more kinds of noble metal catalyst fine particles are selected and supported according to the gas to be removed, catalyst performance can be efficiently expressed in a wide temperature range from low temperature to high temperature.

  Furthermore, the cerium oxide catalyst carrier 100 of the third embodiment of the present invention is an inorganic fine particle in which the cerium oxide catalyst fine particles 2-b are chemically bonded 4 (covalently bonded) by the dehydration condensation reaction of the silane monomer 3 on the surface of the fine particles. It is held on the substrate 1 by being held inside the 2-a group 10.

  That is, the cerium oxide catalyst carrier 100 according to the third embodiment of the present invention uses the silane monomer 3 having an unsaturated bond part or a reactive functional group and having excellent reactivity, so that the chemical bond 4 between the silane monomers 3 is 4. By bonding a plurality of inorganic fine particles 2-a on the substrate 1 together with each other, and forming a chemical bond 4 between the silane monomer 3 on the surface of the inorganic fine particles 2-a facing the substrate 1 and the surface of the substrate 1, Inorganic fine particles 2-a are fixed on the substrate 1.

  The cerium oxide catalyst fine particles 2-b are dispersed and held in a space 5 formed by the bonds between the inorganic fine particles 2-a and the bonds between the inorganic fine particle 2-a group 10 and the substrate 1. The space 5 communicates with the external space, and the cerium oxide catalyst fine particles 2-b are held on the substrate 1 in a state where the catalyst performance is maintained.

  That is, the cerium oxide catalyst fine particles 2-b according to the third embodiment of the present invention include at least the inorganic fine particles 2-a and the silane monomer bonded to the inorganic fine particles 2-a on the substrate 1 while maintaining the catalyst performance. Surrounded by three.

  The cerium oxide catalyst carrier 100 according to the third embodiment of the present invention is an inorganic fine particle 2-a fixed to the substrate 1 without the cerium oxide catalyst fine particles 2-b as the active component being covered with a binder or the like. It is held in a space 5 formed by the group 10. Therefore, the particle density on the substrate 1 of the cerium oxide catalyst fine particles 2-b can be increased. Thereby, the probability that the passing VOC gas and the cerium oxide catalyst fine particles 2-b come into contact with each other can be increased, and the expression efficiency of the catalytic activity is very high.

  Next, as a representative example, a method for manufacturing the cerium oxide catalyst carrier 100 according to the third embodiment of the present invention will be described. First, the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b in which the silane monomer 3 is chemically bonded to the surface are mixed and dispersed in a dispersion medium such as methanol, ethanol, MEK, acetone, xylene, or toluene. Here, in order to promote the dispersion, a surfactant, a mineral acid such as hydrochloric acid or sulfuric acid, a carboxylic acid such as acetic acid or citric acid, or the like may be added as necessary. Subsequently, the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b are pulverized and dispersed in a dispersion medium using an apparatus such as a bead mill, a ball mill, a sand mill, a roll mill, a vibration mill, or a homogenizer. And a slurry containing cerium oxide catalyst fine particles 2-b.

  In addition, the covalent bond between the inorganic fine particles 2-a and the unsaturated bond portion or the silane monomer 3 having a reactive functional group can be formed by a usual method. For example, the silane monomer 3 is added to the dispersion, A method of forming a thin film composed of the silane monomer 3 by covalently bonding the silane monomer 3 to the surface of the inorganic fine particle 2-a by a dehydration condensation reaction while heating under reflux, or a dispersion obtained by pulverizing the fine particle After adding the silane monomer 3, or after adding the silane monomer 3 to form fine particles by grinding, solid-liquid separation and heating at 100 ° C. to 180 ° C. to dehydrate the silane monomer 3 on the surface of the inorganic fine particles 2-a Examples include a method of covalently bonding by a condensation reaction, and then pulverizing and pulverizing and redispersing.

  Here, after adding the silane monomer 3 to the dispersion liquid obtained by refluxing or pulverizing, or by adding the silane monomer 3 and pulverizing to fine particles, solid-liquid separation is performed from 100 ° C. When the silane monomer 3 is covalently bonded to the surface of the inorganic fine particles 2-a by heating at 180 ° C. by a dehydration condensation reaction, the amount of the silane monomer 3 depends on the average particle diameter of the inorganic fine particles 2-a, but the inorganic fine particles The bonding strength between the inorganic fine particles 2-a and between the inorganic fine particles 2-a and the group 10 of the inorganic fine particles 2-a and the substrate 1 is not a problem in practice as long as it is 0.01% to 40.0% by mass with respect to the mass of 2-a. . There may also be an excess of silane coupling monomer 3 that is not deposited.

  Subsequently, the slurry in which the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b obtained as described above are dispersed is applied to the surface of the substrate 1 to be fixed. Specific examples of the method of applying the slurry in which the inorganic fine particles 2-a and the cerium oxide catalyst fine particles 2-b are dispersed include the spin coating method, the dip coating method, the spray coating method, the cast coating method, and the bar coating method. A micro gravure coating method or a gravure coating method may be used, and the coating is not particularly limited as long as a coating suitable for the purpose can be performed.

  Next, if necessary, after removing the dispersion medium by heat drying or the like, the inorganic fine particles 2-a are bonded together by forming a chemical bond 4 between the silane monomers 3 on the surface of the inorganic fine particles 2-a. The bonded inorganic fine particles 2-a are fixed on the substrate 1 by forming a chemical bond 4 between the silane monomer 3 and the surface of the substrate 1. At this time, the cerium oxide catalyst fine particles 2-b are held by being dispersed and fitted between the inorganic fine particles 2-a or between the inorganic fine particles 2-a and the substrate 1.

  In the present embodiment, it is preferable to use a bonding method by graft polymerization as a method for chemically bonding 4 the substrate 1 and the silane monomer 3.

  Examples of graft polymerization in the cerium oxide catalyst carrier 100 of the present embodiment include graft polymerization using a peroxide catalyst, graft polymerization using heat and light energy, and graft polymerization by radiation (radiation graft polymerization). It is appropriately selected and used depending on the form. A chemical bond between the surface of the inorganic fine particles 2-a and the silane monomer 3 can be formed by treatment with a peroxide catalyst, treatment with heat or light energy, and treatment with radiation.

  Here, in order to perform the graft polymerization of the silane monomer 3 efficiently and uniformly, the surface of the substrate 1 is previously subjected to corona discharge treatment, plasma discharge treatment, flame treatment, chromic acid, perchloric acid, etc. Hydrophilic treatment such as chemical treatment with an alkaline aqueous solution containing an oxidizing acid aqueous solution or sodium hydroxide may be performed.

  In addition, what is necessary is just to manufacture the cerium oxide catalyst support body of 1st and 2nd embodiment of this invention using the prescription similar to the inorganic fine particle 2-a in the said description for the cerium oxide catalyst fine particle 2-b.

  As described above, according to the cerium oxide catalyst carrier 100 of the present embodiment, the cerium oxide catalyst fine particles 2-b are dispersed and held in the group of inorganic fine particles 2-a bonded to the substrate 1. For this reason, since the cerium oxide catalyst fine particles 2-b are firmly held on the substrate 1, peeling or the like can be suppressed.

  Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only these examples.

  In the production of the cerium oxide catalyst support of the following Examples 2, 3, 4 and Comparative Example 2 by the method of the present invention, an electrocurtain type electron beam irradiation device (manufactured by Iwasaki Electric Co., Ltd., CB250 / 15 / 180L) was used. This was carried out by electron beam graft polymerization.

Example 1
Commercially available zirconia fine particles (Nippon Denko Co., Ltd., PCS) are 10.0% by mass with respect to methanol as inorganic fine particles, and 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-503) is inorganic as silane monomer. After adding 5.0% by mass to the fine particles and adjusting the pH to 3.0 with hydrochloric acid, the mixture was pulverized and dispersed to an average particle size of 20 nm by a bead mill. Thereafter, solid-liquid separation was performed with a freeze dryer, and heating was performed at 120 ° C., and a silane monomer was chemically bonded to the surface of the zirconia fine particles by a dehydration condensation reaction to form a coating. The obtained surface-treated zirconia fine particles and commercially available cerium oxide fine particles having a specific surface area of 143 m ² / g (CeO ₂ (BB), manufactured by Shin-Etsu Chemical Co., Ltd.) were used as a solvent, and the average particle size was again reduced to 45 nm by a bead mill. By pulverizing and dispersing, each particle obtained a dispersion solution. At this time, the filling amount of cerium oxide was 40 wt% with respect to the solid content.

  A glass fabric (manufactured by Sakai Sangyo Co., Ltd.) was immersed in the dispersion solution, and the excess was removed with an air blower, followed by drying at 130 ° C. for 15 minutes. Next, the glass fabric coated with the cerium oxide fine particle dispersion is irradiated with an electron beam at an acceleration voltage of 200 kV for 5 Mrad, whereby the zirconia fine particles are bonded to the glass fabric by graft polymerization of the silane monomer, and the cerium oxide fine particles are contained in the group. As a result, a cerium oxide catalyst carrier fixed in a dispersed state was obtained.

(Examples 2 to 5)
Commercially available cerium oxide fine particles having a specific surface area of 143 m ² / g (Shin-Etsu Chemical Co., Ltd., CeO ₂ (BB)), methanol as a solvent and 3-methacryloxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.) as a silane monomer Manufactured by KBM-503) was added to 3.0% by mass of the inorganic fine particles, and the pH was adjusted to 3.0 with hydrochloric acid, followed by pulverization and dispersion with a bead mill. Thereafter, solid-liquid separation was performed by a freeze dryer, and heating was performed at 120 ° C., and a silane monomer was chemically bonded to the surface of the cerium oxide fine particles by a dehydration condensation reaction to form a coating. The obtained surface-treated fine particles were averaged to 45 nm (Example 2), 105 nm (Example 3), 310 nm (Example 4), and 520 nm (Example 5) by using a bead mill with methanol as a solvent. A dispersion solution of finely divided cerium oxide catalyst particles obtained by pulverizing and dispersing again was obtained. After that, a catalyst carrier that is a glass fabric was obtained in the same manner as in Example 1.

(Example 6)
A commercially available stainless steel mesh (manufactured by NBC Metal Mesh Co., Ltd., ST325-23) was immersed in a 63% nitric acid aqueous solution heated to 70 ° C. for 10 minutes to form an oxide film on the stainless steel surface. Next, the dispersion used in Example 1 was applied to a stainless steel mesh on which an oxide film was formed by airless spraying and dried at 130 ° C. for 10 minutes. After that, irradiation with 5 Mrad at an acceleration voltage of 200 kV gave a cerium oxide catalyst carrier in which zirconia fine particles were immobilized in a state where cerium oxide fine particles were dispersed in zirconium fine particles on the stainless steel mesh surface by graft polymerization of silane monomer. .

(Example 7)
A cloth-like filter was produced with heat-generating fibers (Softelec, manufactured by Teijin Limited). The surface of the heating element filter was immersed in the dispersion used in Example 1, and the excess dispersion was removed with a blower and dried at 130 ° C. for 50 minutes. After that, the electron beam was irradiated under the same conditions as in Example 1, and the zirconia fine particles were bonded to the surface of the filter woven by soft tex by graft polymerization of the silane monomer, and fixed with the cerium oxide fine particles dispersed in the group. A cerium oxide catalyst carrier was obtained.

(Example 8)
A chromium thin film was formed on one side of a 50 μm thick polyimide film (Mitsui Chemicals, Aurum) by sputtering. Then, a pair of electrodes was formed in the vicinity of the opposite sides of the film on the chrome thin film surface by screen printing with silver paste. Next, the dispersion used in Example 1 was applied to the surface of the chromium thin film on which the electrode was formed by airless spraying and dried at 130 ° C. for 5 minutes. Thereafter, an electron beam is irradiated under the same conditions as in Example 1, the zirconia fine particles are bonded to the chromium thin film on the film surface by graft polymerization of the silane monomer, and the cerium oxide fine particles are fixed in a dispersed state within the group. A cerium oxide catalyst carrier was obtained.

(Comparative Example 1)
In Example 2, tetramethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-504) was added as a binder component instead of the silane monomer, except that 50.0% by mass was added to the cerium oxide fine particles. Similarly, after obtaining a dispersion solution, a glass fabric (manufactured by Sakai Sangyo Co., Ltd.) is immersed in the dispersion solution, and the excess is removed with an air blower, followed by drying at 130 ° C. for 15 minutes, and a cerium oxide catalyst carrier. Got.

(Comparative Example 2)
Example 2 except that a dispersion solution of cerium oxide fine particles dispersed in an average particle size of 800 nm was used instead of the dispersion solution of cerium oxide fine particles dispersed in an average particle size of 45 nm in Example 2 A sample was prepared in the same procedure as described above.

<Supported amount>
The metal mass ratio of cerium to the mass of the sample carrying cerium oxide catalyst fine particles was measured with an inductively coupled plasma emission spectroscopic analyzer (manufactured by SII Nanotechnology Inc., SPS3520).

<VOC removal rate>
The zirconia fine particle and cerium oxide fine particle-carrying filter obtained in Example 1 was placed in a 10 g stainless catalyst reaction tube. In order to make the weight of the filter obtained in Example 1 and cerium oxide the same, 6.6 g of the cerium oxide catalyst fine particle-carrying filter obtained in Examples 2 to 5 and Comparative Examples 1 and 2 was placed in a stainless steel catalyst reaction tube. .

  The filter carrying zirconia fine particles and cerium oxide fine particles obtained in Examples 6 and 7 was punched into an outer shape of 20φ with a press die. A part of the metal part of the outer peripheral part of the filter was exposed, 20 sheets were stacked, and the exposed metal part was brought into contact so that the exposed metal part of each filter was in contact with the inside of the stainless steel reaction tube. Electrodes are formed before and after the reaction tube, an AC voltage of 110 V is applied to heat the filter woven with stainless steel mesh and heating fibers, and a thermocouple is attached to the inside of the reaction tube. The temperature was adjusted to 200 ° C.

  The catalyst body obtained in Example 8 was cut into a strip having a width of 10 mm and a length of 300 mm so that a pair of electrodes remained at the ends of the strip, and a copper wire was applied so that an alternating voltage could be applied to the formed pair of electrodes. They were combined, rolled into a spiral shape, and filled into a stainless steel reaction tube. A thermocouple was attached to the inside of the reaction tube, and an AC voltage of 110 V was applied to the chromium thin film formed on the polyimide film surface to generate heat, and the inside of the reaction tube was adjusted to 200 ° C.

Adjust the flow rate of toluene, isopropyl alcohol (IPA), methyl ethyl ketone (MEK), and ethyl acetate at a concentration of about 700 ppm into the reaction tube filled with the catalyst so that SV = 3000 h ^-1 separately, and each gas is made of stainless steel. Pass through catalyst reaction tube. The gas that passed through the stainless steel catalyst reaction tube was sealed in a Tedlar pack, and the VOC concentration in the Tedlar pack was measured using gas chromatography (Agilent Technology, 7890A GC). At this time, the temperature of the part where the catalyst filter and VOC gas contact was kept at 200 ° C., and the test was conducted. Table 1 shows the measurement results of Examples 1 to 8 and Comparative Examples 1 and 2.

The VOC decomposition rate (%) in Table 1 is calculated using the following formula.
VOC decomposition rate (%) = [{(VOC concentration before contact) − (VOC concentration after contact)} / (VOC concentration before contact)] × 100
In addition, the CeO ₂ supporting capacity is the presence or absence of cerium oxide catalyst fine particles when the cerium oxide catalyst fine particle supported filter after the decomposition performance test is immersed in isopropyl alcohol and irradiated with ultrasonic waves for 1 hour. Was visually observed and evaluated in three stages.

  From the above results, in Comparative Example 2, it was confirmed that the cerium oxide particles were difficult to carry on the filter. In Comparative Example 1, it was confirmed that the catalyst performance was not exhibited by the binder.

  On the other hand, it was confirmed that the cerium oxide catalyst support obtained in Examples 1 to 8 of the present invention showed extremely high activity against VOC. It also has a sufficient carrying capacity for cerium oxide. Therefore, the effectiveness of the present invention was proved.

100: cerium oxide catalyst carrier 1: substrate 2-a: inorganic fine particles 2-b: cerium oxide catalyst fine particles 3: silane monomer 4: chemical bond 5: space portion (space)
10: Group of inorganic fine particles 2-a

Claims (7)

A substrate;
Each has a surface coated with a silane monomer, and has cerium oxide catalyst fine particles fixed to the surface of the substrate through a chemical bond between the silane monomer and the substrate surface and bonded to each other through the chemical bond of the silane monomer. A cerium oxide catalyst carrier for VOC decomposition characterized by the following. A substrate;
Each having a surface coated with a silane monomer, fixed to the surface of the substrate via a chemical bond between the silane monomer and the substrate surface, and bonded to each other by a chemical bond of the silane monomer;
Cerium oxide catalyst fine particles dispersed in the group of inorganic fine particles bonded to each other;
A cerium oxide catalyst support for VOC decomposition, comprising: The cerium oxide catalyst carrier for VOC decomposition according to claim 1 or 2, wherein the cerium oxide catalyst fine particles have an average particle diameter of 500 nm or less. The cerium oxide catalyst carrier for VOC decomposition according to any one of claims 1 to 3, wherein the substrate contains a resin. The cerium oxide catalyst carrier for VOC decomposition according to any one of claims 1 to 3, wherein the substrate contains an inorganic material. VOC decomposing fiber structure formed by using the VOC cracking cerium oxide catalyst carrier according to any one of claims 1 to 5. VOC decomposing filter obtained by using the VOC decomposing fiber structure of claim 6.