JPWO2017188138A1 - VOC degradation agent - Google Patents

Abstract

  VOC decomposing agent containing porous silica carrying platinum or a platinum-containing compound as a VOC decomposing agent that is easy to control properties and performance, is easy to obtain and prepare, and can be used continuously at low temperatures. The porous silica provides a VOC decomposing agent, which is porous silica doped with aluminum. The VOC decomposing agent of the present invention is a volatilization causing ethylene house released from plants such as vegetables, fruits and flowers, volatile organic compounds released from foods and drinks, sick house syndrome released from building materials, paints, resins and the like. It is suitably used for decomposing volatile organic compounds and volatile organic compounds discharged into the atmosphere from vehicles and factories.

Description

  The present invention relates to a VOC decomposing agent, a freshness-preserving agent, an environmental purification agent, and an article provided with these, as well as a VOC decomposing method, a freshness-holding method, and an environmental purification method.

  In recent years, volatile organic compounds (VOC) have become a problem. In the field of food and drink, ethylene, which promotes the maturity of vegetables, and acetaldehyde, methyl mercaptan, trimethylamine, etc., which cause bad odor, are regarded as problems. Adsorption by activated carbon, oxidation using photocatalysts and metal catalysts Disassembly etc. are done. In addition, VOC is one of the causes of air pollution related to suspended particulate matter and photochemical oxidants, and efforts such as emission control are being studied.

  For example, Patent Document 1 discloses an adsorbent for deodorization in a sewage treatment plant, in which bromine, sulfuric acid, and alkali metal halide are uniformly supported on activated carbon.

  In Patent Document 2, a layer containing at least two kinds of photocatalyst particles of titanium oxide and zinc oxide is formed on a base material, and the 50% particle diameter of zinc oxide is larger than the 50% particle diameter of the titanium oxide. An indoor space deodorizing material characterized in that is larger is disclosed.

  In Patent Document 3 and Non-Patent Document 1, cerium-zirconium-bismuth composite oxide and precious metal fine particles (derived from platinum colloid) are supported on the support surface for an ethylene catalytic combustion reaction that does not require light irradiation. A catalyst is disclosed.

Japanese Patent No. 3766771 JP 2003-126234 A JP 2007-229559 A

Nobuhito Imanaka, Toshiyuki Masui, Asako Terada, Hayato Imazu, “Chemistry Letters”, 2008, Vol. 37, p. 42-43

  However, in the invention described in Patent Document 1, the adsorptive capacity decreases with time and is difficult to use for a long time. Since the invention described in Patent Document 2 requires a device for irradiating light, it cannot be easily implemented, and the resolution is not sufficient. The catalysts described in Patent Document 3 and Non-Patent Document 1 include a special composite oxide called cerium-zirconium-bismuth composite oxide as an essential component. For this reason, it cannot be said that there is much room for improvement and material development for various developments regarding the performance and applications of the catalyst. In addition, it is common technical knowledge of those skilled in the art that VOC decomposition using a conventional metal catalyst is performed at a high temperature of 100 ° C. or higher, and it is considered impossible to use in daily life.

  An object of the present invention is to provide a VOC decomposing agent that is easy to control properties, performance, and the like, that is easy to obtain and prepare, and that can be used continuously at low temperatures.

The present invention
[1] A VOC decomposing agent comprising a porous silica carrying platinum or a platinum-containing compound, wherein the porous silica is a porous silica doped with aluminum,
[2] A method for decomposing VOC, wherein VOC is decomposed by contacting VOC with the VOC decomposing agent described in [1] in the presence of oxygen,
[3] A plant freshness-keeping agent comprising the VOC decomposing agent according to [1],
[4] A freshness-preserving agent for foods and drinks comprising the VOC decomposing agent according to [1],
[5] A method for maintaining the freshness of a plant or food or drink, wherein the VOC is decomposed by contacting the VOC with the freshness-preserving agent according to [3] or [4] in the presence of oxygen.
[6] An environmental purification agent comprising the VOC decomposing agent according to [1],
[7] An environmental purification method for decomposing VOC by bringing VOC into contact with the environmental purification agent according to [6] in the presence of oxygen, and
[8] An article comprising the VOC decomposing agent according to [1], the freshness maintaining agent according to [3] or [4], or the environmental purification agent according to [6],
About.

  According to the present invention, it is possible to provide a VOC decomposing agent that is easy to control properties, performance, and the like, is easily available and prepared, and can be used continuously at low temperatures.

It is a graph which shows the diffraction pattern of the position of 0 degree <2 (theta) <8 degree in the powder X-ray diffraction of the VOC decomposition agent of each Example, a reference example, and a comparative example. It is a graph which shows the diffraction pattern of the position of 30 degrees <2 (theta) <50 degrees in the powder X-ray diffraction of the VOC decomposition agent of each Example, a reference example, and a comparative example.

  The VOC decomposing agent of the present invention contains porous silica carrying platinum or a platinum-containing compound (hereinafter also referred to as “platinum or the like”). The porous silica in the present invention means a substance mainly composed of a silicon oxide having a porous structure, and is doped with aluminum. The present inventors have newly found that porous silica carrying platinum or the like is excellent in the decomposition activity of VOC, and by doping the porous silica with aluminum, the VOC of platinum when carrying platinum or the like is found. The present invention was completed by finding that the decomposition activity and its durability were further improved. Although this mechanism is not clear, by doping aluminum, a solid acid point is expressed in the pores of porous silica, the surface of the pore is hydrophilized, and the solid acid point works as a promoter. It is presumed to promote the decomposition reaction of VOC.

  In addition, by expressing solid acid sites in porous silica, neutralizing basic substances such as trimethylamine and preventing the structure of porous silica from collapsing also contributes to improved durability. Presumed.

  The average pore diameter of the porous silica is preferably 1 nm or more from the viewpoint of promoting the progress of the decomposition reaction, and preferably 15 nm or less from the viewpoint of supporting platinum or the like in the form of particles. From these viewpoints, the average pore diameter of the porous silica is preferably 1 to 15 nm, more preferably 1 to 10 nm, and further preferably 1 to 8 nm. In the present invention, the average pore diameter of the porous silica can be calculated by the BJH method based on nitrogen adsorption / desorption.

The specific surface area of the porous silica is preferably 300 m ² / g or more from the viewpoint of increasing the amount of platinum or the like supported, and is preferably 2000 m ² / g or less from the viewpoint of realizing the production. From these viewpoints, the specific surface area of porous silica is preferably 300~2000m ² / g, more preferably 500 to 1500 ² / g, more preferably 600~1200m ² / g. In the present invention, the specific surface area of the porous silica can be calculated by the BET method by nitrogen adsorption / desorption.

The total pore volume of the porous silica is preferably 0.4 cm ³ / g or more from the viewpoint of improving the contact efficiency with VOC, and preferably 3.0 cm ³ / g or less from the viewpoint of realizing the production. From these viewpoints, the total pore volume of the porous silica is preferably 0.4 to 3.0 cm ³ / g, more preferably 0.45 to ² cm ³ / g, and further preferably 0.5 to 1.5 cm. ³ / g. In the present invention, the total pore volume of the porous silica can be calculated by the BET method by nitrogen adsorption / desorption.

  Furthermore, the porous silica preferably has at least one peak at a position where the d-spacing of X-ray diffraction is larger than 2.0 nm. The X-ray diffraction peak means that there is a periodic structure having a d value corresponding to the peak angle in the sample. Therefore, the presence of one or more peaks at the diffraction angle corresponding to a d value of 2.0 nm or more means that the pores are regularly arranged at intervals of 2.0 nm or more. In this invention, the porous silica having pores regularly arranged in this way is also referred to as mesoporous silica. The d interval is preferably 2.0 to 25.0 nm, more preferably 2.5 to 20.0 nm, and still more preferably 3.0 to 18 nm. In the present invention, the X-ray diffraction pattern of porous silica can be measured by a powder X-ray diffractometer using CuKα rays as an X-ray source.

  Although it does not specifically limit as a manufacturing method of porous silica, For example, it can manufacture as follows. First, an inorganic raw material and an organic raw material are mixed and reacted to form an organic matter-inorganic matter composite in which an inorganic matter skeleton is formed around the organic matter as a template. Subsequently, porous silica is obtained by removing organic substances from the obtained composite.

  Inorganic raw materials include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane, sodium silicate, kanemite, and NaHSi. ₂O₅・ 3H₂O), silica, silica-metal composite oxide and the like. These inorganic raw materials form a silicate skeleton. These can be used alone or in admixture of two or more.

  Although the organic raw material used as a casting_mold | template is not specifically limited, For example, surfactant etc. are mentioned. The surfactant may be any of cationic, anionic, and nonionic, specifically, alkyltrimethylammonium (preferably alkyltrimethylammonium having an alkyl group having 8 to 22 carbon atoms). , Alkylammonium, dialkyldimethylammonium, benzylammonium chloride, bromide, iodide or hydroxide, fatty acid salt, alkylsulfonate, alkylphosphate, polyethylene oxide nonionic surfactant, primary alkyl Examples include amines and triblock copolymer type polyalkylene oxides. These can be used alone or in admixture of two or more.

  When mixing an inorganic raw material and an organic raw material, a suitable solvent can be used. Although it does not specifically limit as a solvent, For example, water, an organic solvent, the mixture of water and an organic solvent, etc. are mentioned.

  The formation method of the complex of inorganic and organic is not particularly limited. For example, after dissolving the organic raw material in a solvent, adding the inorganic raw material and adjusting to a predetermined pH, the reaction mixture is brought to a predetermined temperature. A method of carrying out the condensation polymerization reaction while holding is mentioned. The reaction temperature of the polycondensation reaction varies depending on the type and concentration of the organic raw material and inorganic raw material to be used, but is usually preferably about 0 to 100 ° C, more preferably 35 to 80 ° C.

  The reaction time for the polycondensation reaction is usually preferably about 1 to 24 hours. In addition, the above condensation polymerization reaction may be performed either in a stationary state or in a stirring state, or may be performed in combination.

  By removing the organic raw material from the composite obtained after the polycondensation reaction, porous silica can be obtained. The removal of the organic substance from the complex of the organic substance and the inorganic substance can be performed by a method such as a method of baking at 400 to 800 ° C. or a method of treating with a solvent such as water or alcohol.

  In the present invention, the porous silica is preferably mesoporous silica in which pores are regularly arranged from the viewpoint of pore volume. For example, mesoporous silica is obtained by dispersing sodium silicate in an aqueous solution containing a surfactant, adding hydrochloric acid while heating and stirring to adjust the pH of the dispersion, and washing and drying the obtained solid product. It is obtained by firing at about 400 to 800 ° C.

  In the present invention, the method for doping aluminum into porous silica is not particularly limited, but in the process of producing porous silica, the aluminum salt is simultaneously mixed with the inorganic raw material and the organic raw material in the solution. Examples thereof include a method of mixing, a method of impregnating and baking an aluminum solution after forming a composite of an inorganic substance and an organic substance, and a method of impregnating and baking porous silica in an aluminum solution. Among these, from the viewpoint of a simple method, a method of simultaneously mixing an aluminum salt when mixing an inorganic raw material and an organic raw material in a solution is preferable. As a specific example of such a method, sodium silicate is dispersed in an aqueous solution containing a surfactant and an aluminum salt, hydrochloric acid is added with heating and stirring to adjust the pH of the dispersion, and the resulting solid product is obtained. Examples include a method of baking at about 400 to 800 ° C. after washing and drying.

  Although it does not specifically limit as a raw material of the aluminum to dope, For example, water-soluble and oil-soluble aluminum salts, such as aluminum nitrate, aluminum chloride, aluminum sulfate, etc. are mentioned. These can be used alone or in admixture of two or more.

  The amount of aluminum to be doped is preferably 0.05 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and still more preferably from the viewpoint of catalytic activity with respect to 100 parts by mass of porous silica. 1 to 5 parts by mass.

  In the present invention, examples of the platinum-containing compound supported on the porous silica include platinum chloride, platinum oxide, platinum hydroxide, chloroplatinate, and alloys with other metals.

  In the present invention, the metal particle diameter in platinum or a platinum-containing compound supported on porous silica is preferably 0.5 to 7 nm, more preferably 0.7 to 5 nm, and still more preferably from the viewpoint of catalytic activity. 1 to 4 nm. In the present invention, the metal particle diameter in platinum or a platinum-containing compound can be calculated from the diffraction peak at 37 ° <2θ <42 ° obtained by powder X-ray diffraction using the Scherrer equation. In the case where no peak is observed at a position of 37 ° <2θ <42 °, the metal particle diameter in platinum or a platinum-containing compound can be calculated from CO pulse adsorption.

  In the present invention, the platinum or platinum-containing compound supported on the porous silica preferably has no peak at a diffraction angle 2θ of 37 to 42 ° in X-ray diffraction. The X-ray diffraction peak at the above position is a peak due to the (111 plane) of the supported platinum or platinum-containing compound particles, and the fact that this peak is not detected means that the particles are fine and the particle diameter is approximately 5 nm. This means that there are no large particles exceeding. In the present invention, the X-ray diffraction pattern of the VOC decomposing agent can be measured by a powder X-ray diffractometer using CuKα rays as the X-ray source.

  The content of platinum or the platinum-containing compound in the VOC decomposing agent of the present invention is preferably 0.1% by mass or more from the viewpoint of catalytic activity, and preferably 5% by mass or less from the viewpoint of production cost. From these viewpoints, the content of platinum or the platinum-containing compound is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and further preferably 0.1 to 2% by mass in the VOC decomposing agent. It is.

  A VOC decomposing agent in which platinum or a platinum-containing compound is supported on porous silica doped with aluminum is, for example, a mixture of a platinum compound containing a platinum atom, a platinum raw material such as a platinum complex, and porous silica doped with aluminum. Can be obtained by reducing Specifically, for example, an aqueous solution containing a platinum raw material is prepared, impregnated with porous silica doped with aluminum, dried, then reduced, and the porous silica doped with aluminum is platinum or a platinum-containing compound. Can be obtained.

  Examples of the platinum raw material include chloroplatinic acid, dinitrodiammine platinum, and tetraammineplatinum nitrate.

  The temperature condition for drying the aluminum-doped porous silica impregnated in the aqueous solution containing the platinum raw material is not particularly limited, but is preferably about 50 to 200 ° C.

  As a reduction method, a method of treating with a reducing agent, heat, light, or the like can be used, and conditions for generating platinum particles by decomposition of the platinum raw material are appropriately set. Since excessive treatment may increase the particle diameter due to sintering of the generated platinum particles, it is necessary to set appropriate conditions.

  For example, when chloroplatinic acid is used, it is preferable to use hydrogen as a reducing agent and to perform the treatment under a temperature condition of 100 to 400 ° C.

  Platinum or platinum-containing compounds are preferably supported in the pores rather than outside the pores of the porous silica because the catalytic activity decreases when these become coarse particles due to particle growth. Platinum or platinum particles supported (attached) outside the pores can be removed by washing with running water or the like.

  In the VOC decomposition agent of the present invention, VOC decomposition by a conventional metal catalyst is performed at a high temperature of 100 ° C. or higher, while it is common knowledge of those skilled in the art. Can last. The temperature conditions for using the VOC decomposing agent of the present invention are not particularly limited, but can be used in an atmosphere of 80 to -40 ° C, and considering use in daily life, 40 ° C or less or 30 ° C or less. More specifically, it is 15 to 0 ° C. when used in a refrigerator, and −5 to −25 ° C. when used in a freezer.

  Therefore, the present invention provides a VOC decomposition method in which VOC is decomposed by contacting the VOC with the VOC decomposer of the present invention in the presence of oxygen under the above temperature conditions. In addition, although the example in the preservation | save of food / beverage products, a plant, etc. is shown below as the objective of VOC decomposition | disassembly, this invention is not limited to this. It may be used for other purposes such as air purification by decomposing and removing odorous substances and pollutants in the air. As the air cleaning, indoor and outdoor air cleaning can be aimed. Examples of indoor air cleaning include decomposition of volatile organic compounds that cause sick house syndrome released from building materials, paints, resins, and the like. The outdoor air purification can also be aimed at decomposing environmental pollutants and contributing to environmental purification by decomposing volatile organic compounds discharged into the atmosphere from vehicles and factories. That is, the present invention further provides an environmental purification agent containing a VOC decomposing agent, and an environmental purification method for decomposing VOC in the presence of oxygen by contacting the VOC and the environmental purifying agent under the temperature conditions. is there.

  Examples of the environmental purification method include a method of using the environmental purification agent of the present invention in a place where the VOC concentration in the atmosphere or indoor air is 0.01 to 2000 ppm and 100 to −40 ° C. Such places include the vicinity of roads with heavy traffic, inside and outside factories, indoors, and furniture. As the usage mode of the environmental purification agent of the present invention, a powder catalyst is used as it is, or various binders and base materials are appropriately used together and processed into fibers, non-woven fabrics, paper, pellets, slurries, etc. Inlet / exhaust ports, air purifiers, air conditioners, air stirrers and other filter parts, wall materials, floor materials, bottom materials, paints, carpets, curtains, etc. Examples of the decontaminating agent that is filled in and installed in factories, warehouses, houses, furniture, and the like.

  Examples of the VOC decomposed by the VOC decomposing agent according to the present invention include hydrocarbons, organic acids, aldehydes, sulfur compounds, and nitrogen compounds.

  The hydrocarbon is not particularly limited as long as it is a compound composed of carbon and hydrogen, and examples thereof include ethylene, propylene, butene, acetylene, and toluene.

For example, in the case of ethylene, in the following decomposition reaction of ethylene catalyst, conventionally, decomposition to acetaldehyde (CH ₃ CHO) and acetic acid (CH ₃ COOH) was common, but in the VOC decomposition agent of the present invention, It can be broken down into carbon dioxide and water.

  Ethylene is released from various plants such as fruits, vegetables and flowers, and the released ethylene has an action of promoting the decay of plants. The VOC decomposing agent of the present invention can not only efficiently decompose ethylene even at a low temperature, but also the respiration activity of the plant and the aging of the plant are suppressed by the carbon dioxide generated by the decomposition. Therefore, the VOC decomposing agent of the present invention is extremely useful as a plant freshness retaining agent.

  The organic acid is not particularly limited as long as it is a compound having a carboxyl group, and examples include acetic acid, butyric acid, valeric acid, caproic acid, and benzoic acid.

  The aldehyde is not particularly limited as long as it is a compound having an aldehyde group, and examples include formic acid, formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde, hexanal, nonenal and the like.

  Examples of the sulfur compound include methyl mercaptan, ethyl mercaptan, mercaptoethanol and the like.

  Examples of the nitrogen compound include trimethylamine, triethylamine, ethylamine, ethylenediamine, and ammonia.

  Organic acids, aldehydes, sulfur compounds, and nitrogen compounds are released, for example, in the course of fish and meat rot and cause odor. In addition, when storing food or drink, when the stored object is made to be weakly acidic by causing carbon dioxide to act on the stored object, there is some VOC around the stored object. If it remains, the action of carbon dioxide on the material to be preserved is hindered by VOC, making it difficult to maintain freshness. The VOC decomposing agent of the present invention is very useful as a freshness-preserving agent for foods and drinks because it can decompose VOC efficiently even at low temperatures and increase the carbon dioxide gas concentration. In addition, food / beverage products refer to what contains both a drink and solid food.

  As described above, the freshness-keeping agent containing the VOC decomposing agent of the present invention is extremely useful. Therefore, the present invention further provides a freshness maintaining method in which VOC is decomposed by bringing the VOC and the freshness maintaining agent of the present invention into contact with each other under the above temperature conditions in the presence of oxygen. In addition, it is not limited to the said food-drinks and a plant as a target of freshness maintenance, What is necessary is just a thing in which freshness falls by presence of VOC.

  As a freshness keeping method, for example, the freshness keeping agent of the present invention is used in a place where the VOC concentration in the air is 0.01 to 2000 ppm, 80 to -25 ° C. The method of doing is mentioned. Examples of such places include indoors, warehouses, refrigerators, freezers, showcases, containers, transport cases, trucks, and the inside of packaging. As a usage mode of the freshness-keeping agent of the present invention, the powder catalyst is used as it is, or appropriately combined with various binders and base materials, and processed into fibers, nonwoven fabrics, paper, pellets, slurries, etc. As a filter for air conditioners, air stirrers, etc., as wall materials, floor materials, bottom materials, paints, carpets, curtains, etc. Examples include installation inside factories, warehouses, houses, home appliances and packaging materials.

  The VOC decomposing agent, freshness maintaining agent, and environmental cleaning agent of the present invention can be provided in various articles. Specific examples of articles comprising the VOC decomposing agent, freshness-keeping agent, and environmental purification agent of the present invention include, for example, bags, containers, filters, refrigerators, freezers, containers, air conditioners, vehicles, ships, aircrafts, and the like. Can be mentioned.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Production Example 1
(Synthesis of aluminum-doped porous silica support)
50 g of water glass (No. 1 sodium silicate) (SiO ₂ / Na ₂ O = 2.00) was added to 1 L of ion-exchanged water containing 0.04 mol and 0.02 mol of hexadecyltrimethylammonium bromide and aluminum chloride hexahydrate, respectively. Added and dissolved at 70 ° C. Further, 2N HCl was added to adjust the pH to 8.5, and the mixture was stirred at 70 ° C. for 3 hours. Thereafter, washing with water was repeated 5 times and dried at 40 ° C. The dried powder was heated in nitrogen gas at 450 ° C. for 3 hours, then calcined in air at 700 ° C. for 6 hours, and aluminum-doped porous in which 2.85 parts by mass of aluminum was doped with respect to 100 parts by mass of porous silica. Silica support A was obtained.

Production Example 2
(Synthesis of aluminum-doped porous silica support)
50 g of water glass (No. 1 sodium silicate) (SiO ₂ / Na ₂ O = 2.00) was added to 1 L of ion-exchanged water containing 0.04 mol and 0.02 mol of docosyltrimethylammonium chloride and aluminum chloride hexahydrate, respectively. Added and dissolved at 70 ° C. Further, 2N HCl was added to adjust the pH to 8.5, and the mixture was stirred at 70 ° C. for 3 hours. Thereafter, washing with water was repeated 5 times and dried at 40 ° C. The dry powder was heated in nitrogen gas at 450 ° C. for 3 hours, then calcined in air at 700 ° C. for 6 hours, and 2.28 parts by mass of aluminum doped with 100 parts by mass of porous silica. Silica support B was obtained.

Production Example 3
(Synthesis of aluminum-doped porous silica support)
50 g of water glass (No. 1 sodium silicate) (SiO ₂ / Na ₂ O = 2.00) was added to 1 L of ion-exchanged water containing 0.04 mol of hexadecyltrimethylammonium chloride and dissolved at 70 ° C. Further, 2N HCl was added to adjust the pH to 8.5, and the mixture was stirred at 70 ° C. for 3 hours. Thereafter, washing with water was repeated 5 times, followed by further rinsing with ethanol, followed by stirring at room temperature for 1 hour in 1 L of ion-exchanged water containing 0.14 mol of aluminum chloride hexahydrate. This was filtered off and the filtrate was dried at 40 ° C. This dry powder was calcined in air at 700 ° C. for 6 hours to obtain an aluminum-doped porous silica carrier C doped with 3.92 parts by mass of aluminum with respect to 100 parts by mass of porous silica.

The specific surface area (S _BET ) and total pore volume (V _tot ) of the carrier prepared in each production example were measured by the BET method using the adsorption isotherm obtained from the nitrogen adsorption / desorption measurement, and the average pore diameter was measured by the BJH method. (D _meso ) was obtained. The results are shown in Table 1.

Examples 1 to 3 and Reference Example 1
(Platinum supported on porous silica support)
1.0 g of the carrier shown in Table 1 was suspended in 50 mL of water, and a chloroplatinic acid aqueous solution [H ₂ PtCl ₆ aq. The solution was stirred overnight at room temperature. The solvent is distilled off by heating to 50 ° C. using an evaporator, and the obtained powder is vacuum-dried at 6 ° C. for 16 to 18 hours, and hydrogen gas is circulated at 30 mL / min for 8 hours at 200 ° C. By performing the reduction treatment, a VOC decomposing agent having platinum supported on a carrier was obtained.

Comparative Example 1
A commercially available catalyst in which 5% by mass of platinum was supported on silica gel was used as it was as the ethylene decomposing agent of Comparative Example 1.

Powder V-ray diffraction, CO pulse adsorption, and nitrogen adsorption / desorption measurement were performed on the VOC decomposing agents of each Example, Reference Example, and Comparative Example, respectively. X-ray diffraction was measured with RINT-2200 Ultimate II manufactured by Rigaku. Specific measurement conditions are shown below.
X-ray source: CuKα, tube voltage: 40 kV, tube current 40 mA, step width: 0.02 deg. Scan speed: 0.5 deg. / Min. Divergence slit: open, divergence vertical slit: open, scattering slit: open, light receiving slit: 0.6 mm, monochromatic: graphite crystal monochromator

The metal particle diameter (crystallite diameter, D _M ) of platinum or a platinum-containing compound supported by the Scherrer equation was calculated from a diffraction peak at a position of 37 ° <2θ <42 ° obtained by powder X-ray diffraction. . In addition, the metal particle diameter (crystallite diameter, D _M ) of platinum or a platinum-containing compound supported by CO pulse adsorption was calculated for those in which no peak was observed at a position of 37 ° <2θ <42 °. Similarly to the support, the specific surface area (S _BET ) and the total pore volume (V _tot ) are measured by the BET method using the adsorption isotherm obtained by the nitrogen adsorption / desorption measurement, and the average pore diameter (D _meso ). The results are shown in Table 1. The results of powder X-ray diffraction are shown in FIG. 1 and FIG.

Ethylene Decomposition / Removal Evaluation Test Example 1 Ethylene Decomposition / Removal Test at 4 ° C. The VOC decomposing agents of each Example and Comparative Example were compression-molded and screened with a pressure of 2 kN. A granular VOC decomposing agent (355-500 μm) obtained by sieving is charged into a stainless steel reaction vessel and heated at 150 ° C. for 1 hour under helium (75 mL / min.). And the adsorbed water on the surface of the decomposition agent was removed. Using the thus treated VOC decomposer, the following ethylene decomposition removal test was performed. "Smell bag" (bag capacity: 3 L, bag size: 250 x 250 mm, material: polyester film) containing 2.5 L of a reaction gas containing 106 ppm of ethylene (ethylene concentration, approximately 106 ppm; oxygen, 20% by volume; nitrogen, balance) / Tokyo Glass Instruments Co., Ltd.) 1g of decomposition agent, left at 4 ° C for 20 hours, and then measured ethylene concentration in the head space in the odor bag with a gas detector tube (manufactured by Gastec Co., Ltd.) The ethylene decomposition removal activity at 4 ° C. was evaluated. The results are shown in Table 2.

  When the gas in the head space after the reaction for 20 hours was confirmed, carbon dioxide and water were detected. This indicates that ethylene is decomposed into carbon dioxide and water.

Test Example 2 Ethylene Decomposition Removal Test at 25 ° C. Tested in the same manner as in Test Example 1 except that the VOC decomposing agents of each Example, Reference Example, and Comparative Example were used and left to stand at 25 ° C. for 20 hours. Went. The results are shown in Table 3.

Ethylene Decomposition / Evaluation Test Example 3 Water Vapor Resistance Test VOC decomposing agents of each Example, Reference Example, and Comparative Example were compression-molded and screened with a pressure of 2 kN. A granular VOC decomposing agent (355-500 μm) obtained by sieving is charged into a stainless steel reaction vessel and heated at 150 ° C. for 1 hour under helium (75 mL / min.). And the adsorbed water on the surface of the decomposition agent was removed. These VOC decomposing agents were allowed to stand in a space of 40 ° C. and 100% relative humidity for 8 days so that they were not directly exposed to moisture, and the following ethylene decomposing / removing test was performed using the VOC decomposing agent thus treated as it was. went. "Smell bag" (bag capacity: 3 L, bag size: 250 x 250 mm, material: polyester film) containing 2.5 L of a reaction gas containing 106 ppm of ethylene (ethylene concentration, approximately 106 ppm; oxygen, 20% by volume; nitrogen, balance) / Tokyo Glass Instruments Co., Ltd.) 1g of decomposition agent, and after standing at 25 ° C for 20 hours, the ethylene concentration in the head space in the odor bag is measured with a gas detector tube (manufactured by Gastec Co., Ltd.). The ethylene decomposition removal activity at 25 ° C. was evaluated. The results are shown in Table 3.

Test Example 4 Aldehyde Decomposition / Removal Test The following aldehyde decomposition / removal tests were performed using the decomposing agents of each Example and Comparative Example. “Odor bag” (bag capacity: 3 L, containing 2.5 L of reaction gas (acetaldehyde concentration, about 100 ppm; oxygen, 20% by volume; nitrogen, balance: balance gas) containing aldehyde (acetaldehyde) in the amount shown in Table 4 Bag size: 250 × 250 mm, Material: Polyester film / manufactured by ASONE Co., Ltd.), 500 mg of decomposing agent was added and left at 20 ° C. for 21 hours. (Measured by Gastec Co., Ltd.). The results are shown in Table 4.

Test Example 5 Trimethylamine Decomposition / Removal Test The following trimethylamine decomposition / removal test was performed using the decomposition agents of the Examples and Comparative Examples. “Smell bag” (bag capacity: 3 L, bag size: 2.5 L) containing 2.5 L of reaction gas (trimethylamine concentration, about 3 ppm; oxygen, 20 vol%; nitrogen, balance: balance gas) containing trimethylamine in the amount shown in Table 4 250 × 250 mm, material: polyester film / manufactured by ASONE Corporation), 500 mg of decomposing agent is charged, and after standing at 20 ° C. for 21 hours, the concentration of trimethylamine in the head space in the odor bag is measured by a gas detector tube (manufactured by Gastec Corporation) Measured with The results are shown in Table 4.

Test Example 6 Methyl Mercaptan Decomposition / Removal Test The following methyl mercaptan decomposition / removal test was performed using the decomposing agents of the examples and comparative examples. “Odor bag” (bag capacity: 3 L) containing 2.5 L of reaction gas (methyl mercaptan concentration, about 1.5 ppm; oxygen, 20 vol%; nitrogen, balance: balance gas) containing methyl mercaptan in the amount shown in Table 4 , Bag size: 250 × 250 mm, material: polyester film / manufactured by ASONE Co., Ltd.), 500 mg of decomposing agent was added and left at 20 ° C. for 21 hours, and then the concentration of methyl mercaptan in the head space in the odor bag was measured using a gas detector tube (Measured by Gastech). The results are shown in Table 4.

Test Example 7 Formaldehyde decomposition / removal test at 20 ° C. The following formaldehyde decomposition / removal test was performed using the decomposer of each Example. “Smell bag” (bag capacity: 3 L, bag size :) containing 2.5 L of reaction gas containing formaldehyde in the amount shown in Table 5 (formaldehyde concentration, about 400 ppm; oxygen, 20 vol%; nitrogen, balance; balance gas) 250 × 250 mm, material: polyester film / manufactured by ASONE Corporation), 500 mg of decomposing agent is added, and after standing at 20 ° C. for 4 hours, the concentration of formaldehyde in the head space in the odor bag is detected by a gas detector tube (manufactured by Gastec Corporation) Measured with The results are shown in Table 5.

  When the gas in the head space after the reaction for 4 hours was confirmed, carbon dioxide and water corresponding to the initial charged formaldehyde concentration were detected. This indicates that formaldehyde is broken down into carbon dioxide and water.

  Further, the same formaldehyde decomposition removal was confirmed even in a high humidity environment (humidity 90%).

Test Example 8 Formaldehyde decomposition removal test at −20 ° C. Using the decomposition agents of Example 2 and Reference Example 1, a formaldehyde decomposition removal test at −20 ° C. was performed. The test was conducted in the same manner as in Test Example 7 except that the initial charged formaldehyde concentration was about 210 ppm and the sample was allowed to stand at −20 ° C. for 18 hours after the decomposition agent was charged. The results are shown in Table 6.

  From Test Examples 1 to 8, Examples 1 to 3 in which platinum was supported on porous silica were superior to Comparative Example 1 in which platinum was supported on silica gel, and were superior in VOC decomposition activity even at low temperatures. Recognize. Also, in comparison with Test Examples 2 and 3, Examples 1 to 3 in which porous silica is doped with aluminum are superior in durability of VOC decomposition activity than Reference Example 1 that is not doped, and continue at a low temperature. It can be seen that it can be used in a practical manner. Further, from Test Example 8, Example 2 in which porous silica was doped with aluminum was able to remove VOC as much as Reference Example 1 that was not doped even at low temperatures, and from comparison of carbon dioxide concentration after 18 hours. It can be seen that the decomposition rate to carbon dioxide is excellent.

  The VOC decomposing agent of the present invention is a volatilization causing ethylene house released from plants such as vegetables, fruits and flowers, volatile organic compounds released from foods and drinks, sick house syndrome released from building materials, paints, resins and the like. It is suitably used for decomposing volatile organic compounds and volatile organic compounds discharged into the atmosphere from vehicles and factories.

Claims (14)

  A VOC decomposing agent comprising a porous silica carrying platinum or a platinum-containing compound, wherein the porous silica is a porous silica doped with aluminum. ^2. The VOC decomposition according to claim 1, wherein the porous silica has an average pore diameter of 1 to 15 nm, a specific surface area of the porous silica of 300 to 2000 m ² / g, and the porous silica is mesoporous silica. Agent.   The VOC decomposition agent of Claim 1 or 2 whose content of the said platinum or platinum-containing compound is 0.1-5 mass%, and whose metal particle diameter in the said platinum or platinum-containing compound is 0.5-7 nm.   The VOC decomposition agent in any one of Claims 1-3 for decomposing | disassembling VOC in 30 degrees C or less atmosphere.   The VOC decomposing agent according to any one of claims 1 to 4, which has no diffraction peak at a position of 37 ° <2θ <42 ° in X-ray diffraction.   The VOC decomposing agent according to any one of claims 1 to 5, for decomposing one or more VOCs selected from the group consisting of hydrocarbons, organic acids, aldehydes, sulfur compounds, and nitrogen compounds.   A method for decomposing a VOC, wherein the VOC is decomposed by contacting the VOC with the VOC decomposing agent according to any one of claims 1 to 6 in the presence of oxygen.   A plant freshness-keeping agent comprising the VOC decomposing agent according to claim 1.   A freshness-preserving agent for foods and drinks comprising the VOC decomposing agent according to any one of claims 1 to 6.   A method for maintaining the freshness of a plant or food or drink, wherein the VOC is decomposed by contacting the VOC with the freshness-keeping agent according to claim 8 or 9 in the presence of oxygen.   An environmental purification agent comprising the VOC decomposing agent according to claim 1.   The environmental purification method which decomposes | disassembles VOC by making VOC and the environmental purification agent of Claim 11 contact in presence of oxygen.   An article comprising the VOC decomposing agent according to any one of claims 1 to 6, the freshness maintaining agent according to claim 8 or 9, or the environmental purifying agent according to claim 11.   14. The article of claim 13, which is a bag, container, filter, refrigerator, freezer, container, air conditioner, vehicle, ship or aircraft.

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