WO2022230343A1

WO2022230343A1 - Decomposer for odorous substance, article including decomposer for odorous substance, and method for decomposing odorous substance using same

Info

Publication number: WO2022230343A1
Application number: PCT/JP2022/008185
Authority: WO
Inventors: 良太橋口; 寛知久; 晃世和田山
Original assignee: 株式会社フルヤ金属
Priority date: 2021-04-27
Filing date: 2022-02-28
Publication date: 2022-11-03
Also published as: JPWO2022230343A1

Abstract

[Problem] To provide a decomposer for odorous substances which decomposes odorous substances even at low temperatures with a small amount of external energy and which retains the decomposition effect over a relatively long period. [Solution] A decomposer for odorous substances which comprises porous silica having an average pore diameter of 1-50 nm and a BET specific surface area of 300-2,000 m2/g and, supported thereon, ruthenium-containing particles having a particle diameter of 1-4 nm.

Description

Odor Substance Decomposing Agent, Article Equipped with Odor Substance Decomposing Agent, and Odor Substance Decomposing Method Using the Same

The present invention relates to an odorant decomposing agent in which particles containing ruthenium are supported on porous silica. The present invention also relates to an odorant decomposing method using an odorant decomposing agent in which particles containing ruthenium are supported on porous silica, and an odorant decomposing article containing the odorant decomposing agent.

According to Article 2 of Japan's Basic Environment Law, offensive odors are classified as pollution along with air pollution, water pollution, soil pollution, noise, vibration, and ground subsidence, and cause damage to human health and the living environment. It is assumed.
It is said that there are more than 400,000 kinds of odorous molecules, and odor is said to be a composite substance of these molecules. Odor is perceived when the concentration of these molecules reaches the human olfactory threshold. Compound groups of odorous molecules include sulfur compounds, nitrogen compounds, aldehydes, hydrocarbons, lower fatty acids, and the like. For example, the smell threshold of methyl mercaptan, which is a sulfur compound, is said to be 0.00007 ppm, and the smell threshold of hydrogen sulfide is said to be 0.0004 ppm. Further, the odor threshold of ammonia, which is a nitrogen compound, is said to be 1.5 ppm, and the odor threshold of trimethylamine is said to be 0.00003 ppm. Generally, these sulfur compounds or nitrogen compounds are said to be odor-causing substances, and methyl mercaptan, hydrogen sulfide, ammonia, and trimethylamine are called the four major malodorous substances.

As a method for reducing the above-described odorous substances, a method of adsorbing odorous substances with activated carbon is known. Activated carbon adsorbs odorants to the adsorption sites of activated carbon and reduces odorants. Therefore, if the adsorption sites of activated carbon become saturated with odorants or other substances, the effect of reducing odorants is lost. As a result, the sustainability of the odorant reduction effect of activated carbon is limited, and periodic maintenance such as desorption of adsorbed odorants and replacement of activated carbon is required.
On the other hand, there is also a method of reducing odorous substances by decomposition of odorous substances instead of adsorption.
Known methods for decomposing odorants include a method of decomposing odorants by photocatalyst or plasma, and a method of decomposing odorants by direct combustion or catalytic combustion.
The method of decomposing odorous substances by means of a photocatalyst is a method of decomposing and removing odorous substances by irradiating a titanium oxide photocatalyst with ultraviolet rays to generate OH radicals and superoxide ions on the surface of the catalyst. Light from sunlight or fluorescent lamps is often used as the light source, but the photocatalyst function is not exhibited in a dark environment. In a light-poor environment, the photocatalyst is irradiated with light generated using an external power source to exert its photocatalytic function, but this requires large-scale equipment and energy from the external power source.
The method of decomposing odorous substances by plasma is a method of performing high-frequency discharge in a gas to be treated containing odorous substances to generate active molecules, radicals, and ozone, and decomposing odors by their oxidizing ability. In order to generate plasma, a discharge device is required, and the equipment becomes large-scale.
The direct combustion method is a method of oxidizing and decomposing odorous substances by burning them in a high temperature environment of about 600°C to 800°C.
Catalytic combustion is a technology in which odorants are oxidized and removed on a catalyst at a temperature in the range of 150°C to 300°C.
Both the direct combustion method and the catalytic combustion method require external energy to sustain a high-temperature environment.

In addition to the above method, Patent Document 1 describes at least one of a mixture of copper oxide and manganese oxide and a composite oxide of copper and manganese, and at least one of hydrophobic zeolite, sepiolite, and alkaline earth metal composite. A deodorizing catalyst characterized by being formed by combining two is disclosed. It is shown that the odorant is oxidized and removed by heating the deodorizing catalyst at a temperature of about 150°C to 350°C.

Patent Document 2 discloses an odorant decomposing agent comprising platinum or a platinum-containing compound supported on porous silica, wherein the odorant is selected from aldehydes, fatty acids, sulfur compounds, and nitrogen compounds. Disclosed is a decomposing agent comprising at least one volatile compound and used in an atmosphere of 80 to -40°C in the presence of oxygen.

Patent Document 3 discloses a catalyst comprising a composite of platinum and ruthenium supported on porous silica, which is used for oxidative decomposition of ethylene or a mercaptan compound in the presence of oxygen.

JP 2006-263613 A WO2017/010472 WO2019/027057

However, the deodorizing catalyst described in Patent Document 1 heats the deodorizing catalyst to 200° C. when removing odorous substances, and the decomposition effect is not sufficient. Further, the decomposing agent for odorous substances described in Patent Document 2 uses platinum, which has a supported amount of platinum of 1% by mass and is relatively expensive. In the catalyst described in Patent Document 3, a composite of platinum and ruthenium is supported, but the amount of platinum supported is 0.5% by mass and the amount of ruthenium supported is 0.5% by mass, and platinum is expensive. is used. Therefore, there is a demand for a decomposing agent that requires little external energy, maintains its decomposing effect on odorous substances, and is relatively inexpensive.
It is an object of the present invention to provide an odorant decomposer which decomposes odorants even at low temperatures requiring little energy from the outside, whose decomposing effect lasts for a relatively long time, and which uses a metal whose cost is lower than that of platinum. .

The present inventors have completed the present invention as a result of diligent studies to solve the above problems. That is, the present invention has the following aspects.

[1]
An odorant decomposing agent comprising porous silica having an average pore diameter of 1 nm to 50 nm and a BET specific surface area of 300 to 2000 m ² /g supporting ruthenium-containing particles having a particle diameter of 1 to 4 nm.
[2]
The odorant decomposing agent according to the above [1], wherein the porous silica is mesoporous silica.
[3]
The odorant decomposing agent according to the above [1] or [2], wherein the amount of ruthenium supported is from 0.1 to 10% by mass.
[4]
The odorant decomposing agent according to any one of [1] to [3], wherein the odorant to be decomposed by the odorant decomposing agent is a sulfur compound or a nitrogen compound.
[5]
The odorant decomposing agent according to [4], wherein the sulfur compound is methyl mercaptan.
[6]
The odorant decomposing agent according to [4], wherein the nitrogen compound is ammonia.
[7]
An odorant-decomposing article comprising the odorant-decomposing agent according to any one of [1] to [6].
[8]
A method for decomposing an odorous substance, comprising contacting the odorant-decomposing agent according to any one of [1] to [6] with an odorant in an atmosphere of 0° C. to 50° C. or less in the presence of oxygen.

According to the present invention, a highly effective odorant decomposing agent is provided without consuming external energy.

1 is a schematic diagram of a fixed-bed flow reactor used in [Example 1] to [Example 6] and [Example 8] to [Example 10]. FIG. Fig. 2 is a schematic diagram of a fixed-bed flow reactor used in [Example 7]. 4 is an image showing the results of STEM measurement of the odorant decomposing agent 1. FIG. 1 is a graph obtained by measuring the peak pore diameter of odorant decomposing agent 1 and plotting BJH.

The odorant decomposing agent of the present invention comprises porous silica having an average pore size of 1 nm to 50 nm and a BET specific surface area of 300 to 2000 m ² /g, and ruthenium-containing particles having a particle size of 1 to 4 nm supported thereon. .

From the viewpoint of catalytic activity, the porous silica used as a catalyst carrier preferably has a large specific surface area. The larger the specific surface area, the larger the amount of metal particles that can be supported. The pore diameter is the pore diameter, and when the peak pore diameter is measured by the BJH method, the range of the pore diameter can be estimated from that value.
From the viewpoint of promoting the catalytic reaction, the average pore diameter is preferably 1 to 10 nm.
The BET specific surface area is preferably 500 to 1500 m ² /g from the viewpoint of supporting more ruthenium-containing particles.

Among the porous silica, mesoporous silica is preferable. Mesoporous silica is a type of silica, and has uniform regular pores of 2 to 10 nm in a honeycomb state and a specific surface area of 1000 m ² /g or more. Since mesoporous silica is characterized by a large specific surface area and regular pores, the reaction is likely to be promoted by the entry of molecules into the pores of mesoporous silica, and an improvement in the reactivity of the catalyst can be expected. In addition, since mesoporous silica has uniform regular pores, it is characterized in that it is easy to synthesize uniform nanoparticles inside the pores.

Mesoporous silica can be produced, for example, according to the method described in JP-A-2017-23889. Specifically, it is as follows.
First, an inorganic raw material and an organic raw material are mixed and reacted to form an organic-inorganic composite having an inorganic skeleton formed around the organic material as a template. Next, porous silica is obtained by removing the organic matter from the resulting composite. Examples of inorganic raw materials include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane and tetrapropoxysilane, sodium silicate, kanemite (NaHSi ₂ O _5.3H ₂ O), silica, and silica-metal composite oxides. be done. These inorganic raw materials form a silicate skeleton.
You may use these individually or in mixture of 2 or more types. Organic raw materials used as templates include, for example, surfactants. Surfactants may be cationic, anionic or nonionic.

A method for forming a composite of an inorganic substance and an organic substance includes, for example, dissolving an organic raw material in a solvent, adding the inorganic raw material, adjusting the pH to a predetermined value, and then performing a polycondensation reaction while maintaining the reaction mixture at a predetermined temperature. method. The reaction temperature of the polycondensation reaction varies depending on the types and concentrations of the organic raw materials and inorganic raw materials used, but is generally preferably about 0 to 100°C, more preferably 35 to 80°C. The reaction time of the polycondensation reaction is preferably about 1 to 24 hours. The above polycondensation reaction may be carried out either in a stationary state or in a stirring state, or in combination thereof.
Porous silica is obtained by removing the organic raw material from the composite obtained after the polycondensation reaction. Organic matter can be removed from the composite of organic matter and inorganic matter by a method of baking at 400 to 800° C., a method of treatment with a solvent such as water or alcohol, or the like.

Ruthenium-containing particles of the present embodiment include ruthenium metal particles, particles containing ruthenium in the form of compounds such as ruthenium chloride and ruthenium oxide, alloy particles, and composite particles.
The alloy particles are two or more types of alloys composed of ruthenium and other metals, and are produced by, for example, converting a precursor of the metal to be alloyed into atoms with a reducing agent, and causing the atoms to self-aggregate and grow grains. For example, a method of obtaining alloy particles by suppressing the process with a protective agent. The alloy particles are preferably nano-alloy particles having a particle size on the order of nanometers.

Composite particles include a core-shell structure containing ruthenium or co-supporting ruthenium and other metals. A method for producing composite particles is, for example, to obtain ruthenium metal particles by hydrogen reduction from a ruthenium salt, and then support another metal around the ruthenium metal particles in a similar manner to obtain ruthenium. A core-shell structure containing Composite particles may also be made in porous silica. For example, after supporting a ruthenium salt in the pores of porous silica by an impregnation method, ruthenium metal particles are obtained by hydrogen reduction, and then another metal is added in the pores of porous silica by a similar method. to co-load ruthenium and other metals within the pores of the porous silica.

By using the ruthenium-containing particles as the alloy particles or composite particles, not only the ability to decompose various odorants is improved, but also odorants possessing functions other than decomposing odorants such as decomposition of ethylene or antibacterial properties. May act as a decomposing agent.
The particles containing ruthenium have a particle size of 1 nm to 4 nm, preferably 1 nm to 2 nm. As the particle size becomes smaller, the specific surface area of the ruthenium-containing particles increases and the catalytic activity improves.
The particle size of the ruthenium-containing particles is preferably controlled by supporting them within the pores of the porous silica. By supporting particles containing ruthenium in the porous silica, it is possible to prevent an increase in particle size due to particle growth and control the particle size to a predetermined value. In addition, it is believed that supporting particles containing ruthenium in the pores of porous silica has a molecular sieving effect in the catalytic reaction and improves catalytic activity and selectivity.
Observation with a transmission electron microscope or the like can confirm whether or not the ruthenium particles are contained in the porous silica.

The other metals include platinum, palladium, rhodium, iridium, gold, silver, copper, rhenium, nickel, cobalt, iron, manganese, tungsten, molybdenum, chromium, and vanadium.

In the odorant decomposing agent of the present invention, particles containing ruthenium are supported on the porous silica, and the amount of ruthenium supported is 0.1 to 10% by mass, where the total amount of the porous silica and ruthenium is 100% by mass. %. The supported amount is preferably 0.1% by mass or more from the viewpoint of catalyst performance, and preferably 5% by mass or less from the viewpoint of production cost.

In the present embodiment, the odorant to be decomposed by the odorant decomposing agent is usually a molecule containing atoms other than carbon and hydrogen, and is a compound that reaches the human olfactory threshold at a relatively low concentration. Such odorous substances include sulfur compounds, nitrogen compounds, aldehydes, hydrocarbons, lower fatty acids and the like. Among these compounds, the odorant decomposing agent of the present invention can be suitably used for nitrogen compounds and sulfur compounds which are generally said to cause odors.

Nitrogen compounds include ammonia, trimethylamine, ethylamine, triethylamine, and ethylenediamine. Among them, the odorant decomposing agent of the present invention can be preferably used for ammonia or trimethylamine, and the odorant decomposing agent of the present invention can be used more preferably for ammonia.

Sulfur compounds include methyl mercaptan, hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, and methyl sulfide. Among them, the odorant decomposing agent of the present invention can be preferably used for methyl mercaptan or hydrogen sulfide, and the odorant decomposing agent of the present embodiment can be more preferably used for methyl mercaptan.

Both nitrogen and sulfur compounds may be generated during the spoilage process of meat, fish and eggs, and sulfur compounds as well as nitrogen compounds are believed to be the main components of garbage odor. Livestock manure and human waste also contain sulfur compounds and nitrogen compounds. When these odorous compounds are contained in the air at a concentration equal to or higher than the olfactory threshold of humans, humans sense odors.
By bringing the odorant decomposing agent of the present embodiment into contact with these odorants, the odorant can be converted into another odorless compound or less odorous compound, the concentration of the odorant is reduced, and the deodorant is deodorized. effect can be obtained.

Articles for decomposing odorous substances comprising the odorant decomposing agent of the present embodiment are those in which the odorant decomposing agent is in the form of powder, pellets, or films, and other moldings containing the odorant decomposing agent of the present invention. Installed or enclosed.
When the odorant decomposing agent is in the form of powder or pellets, the powdery or pelletized odorant decomposing agent is filled in a film or non-woven fabric package or a box-like molding to produce an odorant decomposing article. may be used.

As an article equipped with an odorant decomposing agent, the odorant decomposing agent of the present embodiment can be dispersed in a liquid substance and applied to a substrate for use. Examples of the shape of the substrate include film, sheet, columnar, honeycomb, nonwoven fabric, woven fabric, paper, and felt. , may be uneven. Examples of the material include metal, resin, wood, paper, fiber, natural leather, and synthetic leather.

From the viewpoint of the efficiency of odorant decomposition, the base material is preferably a base material with a large surface area, and from the viewpoint of handling, a honeycomb-shaped base material, nonwoven fabric, or paper is preferable. The term "honeycomb" as used herein is used in a broad sense, and is not limited to regular hexagons. and polygons such as triangles, quadrilaterals, pentagons, and hexagons. The holes may all have the same shape, or may have two or more of these shapes.

Examples of honeycomb-shaped substrates include ceramic honeycombs and paper honeycombs. The component of the ceramic honeycomb preferably consists of a component selected from the group consisting of cordierite, silicon carbide, silicon nitride, alumina, mullite, aluminum titanate, titania and zirconia.

The paper honeycomb is preferably made of paper selected from the group consisting of kraft paper, K-liner paper, reinforced core base paper, water-resistant core base paper, aluminum hydroxide paper, and the like. Among these papers, insulating papers are preferred, and nonflammable or flame-retardant papers are preferred.

A ceramic honeycomb can be manufactured by extruding the above components into a predetermined shape. The paper honeycomb can be produced by continuously forming and laminating the above paper into a flat plate shape, a corrugated shape, a cylindrical shape, a honeycomb shape, or the like. These are appropriately selected and used according to the purpose and environment. A ceramic honeycomb is preferable from the viewpoint of heat resistance, and a paper honeycomb is preferable from the viewpoint of lightness.

Non-woven fabrics include aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyethylene fiber, polypropylene fiber, polyolefin fiber, rayon fiber, low density polyethylene resin, ethylene vinyl acetate resin, copolymerized polyamide resin, copolymerized It is made of fibers such as polyester resin, polyphenylene sulfide resin, polyester/modacrylic resin, etc. From the viewpoint of heat resistance, aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyester/modacrylic resin is preferable. A polyester/modacrylic resin is more preferable from the viewpoint of being rich in flame retardancy and washability from the outside air.

Examples of paper include Japanese paper, Western paper, paperboard (cardboard), wrapping paper (wrapping paper and envelopes), packaging materials, and food packaging materials. Also, food packaging materials are preferable from the viewpoint of being highly resistant to oil and lipids and flame retardant.

When using the article for decomposing an odorous substance of the present embodiment, it is preferably placed in the vicinity of the odor generating source at a temperature of 0° C. to 50° C. in the presence of oxygen, as in the method for decomposing an odorous substance described below. It is preferable to control the flow of the odorant-containing gas so that the odorant-containing gas and oxygen generated from the odor source come into contact with the odorant-decomposing agent of the present invention.
The use of the odorant decomposing article can be in closed or open systems.
As a method for using the article for decomposing odorous substances of the present embodiment, for example, in the case of a closed system with a relatively small space volume such as a kitchen, a toilet, or a refrigerator, gas containing a large amount of sulfur compounds or nitrogen compounds, which are odorous substances, can be used. It is preferable to use it by placing it near the source of the For example, the odorant can be decomposed by placing it in the vicinity of the source of odor, such as a kitchen drain or kitchen garbage thrown away in a trash can. It can be put directly into the drain or brought into direct contact with garbage. The closer the distance between the odor generating source and the odorant decomposing agent is, the better from the viewpoint of odorant decomposing efficiency. In the case of a closed system with a relatively large space volume, such as a home kitchen, the room is filled with odor, and there may be two or more odor sources in the space, or the odor source may not be identified. be. In such a case, an airflow may be generated by a fan or the like, and an odorant decomposing agent may be placed in the flow path of the airflow to decompose the odorant. The airflow can increase the efficiency of decomposing odorants. In addition, by installing a filter coated with an odorant decomposing agent in air conditioners, air purifiers, etc., the odorant and the odorant decomposing agent come into contact with each other on the filter, making it ideal for increasing the efficiency of decomposing odorous substances. be. In the case of an open system such as a livestock factory, a food factory, or a waste disposal facility, where odorous substances are discharged to the outside, install a filter or an odorant decomposing agent applied to a base material of honeycomb structure at the suction port or exhaust port. , the odorous substances in the room are converted into less odorous compounds and discharged outdoors.

The odorant decomposition method of the present invention decomposes an odorant by contacting the odorant decomposing agent with the odorant in an atmosphere of 0°C to 50°C or less in the presence of oxygen. Ordinary catalysts do not have high decomposition ability in an atmosphere of 0°C to 50°C or less, but the odorant decomposing agent of the present invention has decomposition performance of odorants even in an atmosphere of 0°C to 50°C or less. It is possible to decompose odorants with a small amount of external energy. The temperature is preferably 0°C to 30°C.

In the present embodiment, the odorant decomposing agent contacts the odorant in the presence of oxygen, thereby converting the odorant into a less odorous substance, thereby exhibiting an odor reducing effect. Although the details of the decomposition of the odorant are unknown, it is believed that the following reactions are caused by the odorant decomposing agent in the present embodiment, for example.

For example, the decomposition of methyl mercaptan is presumed to be as follows.
(Assumed oxidation reaction of methyl mercaptan)
_2CH3SH + _7O2 → _2H2SO4 ₊ 2CO2 ₊ _2H2O
_CH3SH +3O2→SO2 ₊ _CO2 ₊ _2H2O
_2CH3SH + _3O2 → _2H2S ₊ 2CO2 ₊ 2H2O
2CH3SH+ ₃ / _2O2 →( _CH3 )2S ₊ SO2 ₊ _H2O

2CH3SH

₊ 1/ _2O2 →( _CH3 ) _2S2 ₊ _H2O

For example, the decomposition of ammonia is presumed to have the following reactions.
(Assumed oxidation reaction of ammonia)
2NH3 + ₃ / _2O2 → _N2 + _3H2O
_2NH3 + _2O2 → N2O ₊ _3H2O
_4NH3 + _5O2 → 4NO ₊ 6H2O
_4NH3 + _7O2 → 4NO2 ₊ _6H2O

Methyl mercaptan and ammonia described in the left formula of the above reaction formula are compounds that reach the human olfactory threshold even at low concentrations, but they react with oxygen and decompose into the compounds shown in the right formula of the reaction formula. . The product compound shown in the right-hand side of the reaction formula is a compound that reaches the olfactory threshold of humans at a relatively high concentration, and as a result, it is thought that the odor becomes less perceptible. In addition to the above reaction formula, there are cases in which a compound reaches the human olfactory threshold at a relatively high concentration as a result of passing through other intermediate substances.
The concentration of oxygen present may be the stoichiometric amount of the above reaction formula with respect to the odorant, and may be from 2 to 4 times, preferably from 3 to 4 times, the odorant.
Oxygen coexistence with other gases is preferable from the viewpoint of safety, and coexistence with an inert gas such as nitrogen, helium or argon is preferable.
When oxygen coexists with other gases, the oxygen concentration is preferably 1% by volume or more and 21% by volume or less, more preferably 15% by volume or more and 21% by volume or less.
The odorant decomposition method of the present embodiment is preferably carried out in the presence of air.

In this embodiment, the odorant decomposing agent or odorant decomposing article is placed in a place where odor is generated, such as a toilet, a trash can, or a kitchen, in the presence of oxygen. For example, a pellet-shaped catalyst is placed in a breathable plastic container. By placing it on board, it is possible to decompose and remove odorous substances and reduce odors. It is also possible to apply the odorant decomposing agent to wallpaper, curtains, sheets and the like. Further, by applying the odorant decomposing agent or articles for decomposing odorous substances of the present embodiment to the filters of the exhaust system of the indoor air conditioner and garbage storage area, the odorous substances in the space come into contact with the odorant decomposing agent. , it is also possible to reduce the odor efficiently. By installing the honeycomb-shaped odorant decomposing agent of the present invention, for example, in the exhaust system of a conventional garbage disposal apparatus, odorous substances can be reduced without heating the odorant decomposing agent.

Although the odorant decomposing agent, the odorant decomposing article, and the odorant decomposing method of the present invention have been described above, the present embodiment is not limited to the configuration of the embodiment described above.
For example, in the configuration of the odorant decomposing agent or odorant decomposing article of the present invention, any other configuration may be added or replaced with any configuration that exhibits similar functions. In addition, the odorant decomposition method of the present invention may additionally have any other step in the configuration of the above embodiment, or may be replaced with any step that produces the same action.

The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Decomposition of odorants was evaluated in Examples and Comparative Examples.

(Example 1)
(Synthesis of odorant decomposing agent supporting ruthenium)
A kneaded product of powdery mesoporous silica (TMPS-4R, manufactured by Taiyo Kagaku Co., Ltd.) and alumina was formed into pellets having a diameter of about 1.5 mm and a length of about 4 mm using an extruder. After drying the molded pellets at 80° C. for 24 hours, they were calcined at 500 to 600° C. for 1 hour to obtain mesoporous silica pellets. 1 g of the mesoporous silica pellets was suspended in 50 mL of water, an aqueous ruthenium chloride solution was added dropwise so that the supported amount of ruthenium particles was 1% by mass, and the solution was allowed to stand overnight at room temperature. The suspension was then heated using an evaporator at an oil temperature of about 70° C. and under reduced pressure (3 kPa) to evaporate the solvent, concentrating the suspension and then drying overnight. After that, the mesoporous silica was heated in a nitrogen gas atmosphere for 2 hours at a temperature of 100° C. to 200° C. while flowing nitrogen gas at 500 mL/min. Thereafter, the mesoporous silica was subjected to reduction treatment at 100° C. to 350° C. in a hydrogen gas atmosphere. As a result, an odorant decomposing agent 1 was obtained in which ruthenium particles were supported on the mesoporous silica and the amount of ruthenium supported was 1% by mass.

(Comparative example 1)
(Synthesis of platinum-supported odorant decomposing agent)
An odorant decomposing agent 2 having a supported platinum amount of 1% by mass was obtained in the same manner as in Example 1, except that chloroplatinic acid was used instead of ruthenium chloride.

(Comparative example 2)
(Synthesis of mesoporous silica pellets)
The mesoporous silica pellets obtained in Example 1 were used as odorant decomposing agent 3 .

(BET specific surface area)
The BET specific surface areas of the odorant decomposing agents of Example 1 and Comparative Examples 1 and 2 were obtained by nitrogen adsorption/desorption measurement using a specific surface area/pore size distribution measuring device (BELSORP-miniII, manufactured by Microtrack Bell Co., Ltd.). It was measured by the BET method using the adsorption isotherm. Table 1 shows the measured results.

(Peak pore size)
The peak pore diameters of the odorant decomposing agents of Example 1 and Comparative Examples 1 and 2 were measured by the BJH method using a specific surface area/pore size distribution measuring device (BELSORP-miniII, manufactured by Microtrack Bell Co., Ltd.). Table 1 shows the measured results. Also, the BJH plot of Example 1 is shown in FIG. As a result of FIG. 4, a sharp peak with a peak top of 3.28 nm is confirmed, and the average pore diameter is considered to be in the range of 1 nm to 50 nm.

(pore volume)
The pore volumes of the odorant decomposing agents of Example 1 and Comparative Examples 1 and 2 were measured by the α _S plot method using a specific surface area/pore size distribution measuring device (BELSORP-miniII, manufactured by Microtrack Bell Co., Ltd.). . Table 1 shows the measured results.

For the odorant decomposing agent 1, the average particle size of the primary particles was measured by TEM observation. The average particle diameter of 101 metal primary particles in the mesoporous silica carrier was measured by TEM observation at a magnification of 800,000, and the average particle diameter was 1.72 nm.

In addition, the odorant decomposing agent 1 was photographed by STEM observation. The results are shown in FIG. In FIG. 3, the striped portions are the pores of the porous silica, and the portions that appear as round black dots are the ruthenium particles, and the ruthenium particles are supported along the pores of the porous silica. I know that

(Ammonia decomposition evaluation)
[Example 1]
A fixed-bed flow-type reactor shown in FIG. 1 was prepared, and the ammonia decomposition evaluation of the odorant decomposing agent 1 was performed by the fixed-bed flow-type. As a pretreatment, 50 mg of the odorant decomposing agent 1 was weighed and heated at 150° C. for 2 hours in an air atmosphere using a heating device, and then the reaction tube 5 was filled with the odorant decomposing agent 1 . The reaction tube is not heated, and in a normal temperature atmosphere, a pre-adjusted ammonia-containing helium gas having an ammonia concentration of 100 ppm, an oxygen concentration of 20% by volume, and the balance being helium is circulated from the gas reservoir 1 at a flow rate of 15.3 mL/min. The concentration of ammonia in the ammonia-containing helium gas after passing through the odorant decomposing agent 1 was measured with a detector tube 6 (manufactured by GASTEC). Table 2 shows the results of measuring the outlet concentration of ammonia. The detection lower limit of the detector tube is 0.5 ppm, and the removal rate in Table 2 was calculated by the following formula 1. Table 2 shows the calculated results.
(Formula 1)
Ammonia removal rate (%) = (ammonia concentration in gas reservoir 1 - ammonia concentration measured with detector tube 6) / ammonia concentration in gas reservoir 1 x 100

[Examples 2 and 3]
Evaluation of ammonia decomposition was carried out in the same manner as in Example 1, except that the odorant decomposing agent 1 was changed to the

odorant decomposing agent

2 or 3. Table 2 shows the results.

From Table 2, the removal rate of the odorant decomposing agent 2 of Comparative Example 1 was 2% after 18 hours, and the removal rate of the odorant decomposing agent 3 of Comparative Example 2 was 0% after 17 hours. The odorant decomposing agent 1 maintained a removal rate of about 80% even after 18 hours.

(Ammonia decomposition durability test)
[Example 4]
Using the same fixed-bed flow reactor as in Example 1, an ammonia decomposition test was conducted by a fixed-bed flow system after the odorant decomposing agent 1 was exposed to ammonia for a long period of time. As a pretreatment, 50 mg of the odorant decomposing agent 1 was weighed and heated at 150° C. for 2 hours in an air atmosphere using a heating device. The reaction tube was not heated, and in a normal temperature atmosphere, a previously adjusted ammonia-containing helium gas having an ammonia concentration of 1000 ppm and the balance being helium was passed through the gas reservoir 1 at a flow rate of 15.3 mL/min for 46 hours. After that, the composition of the helium gas containing ammonia is changed to 100 ppm oxygen 20% by volume of ammonia and the balance is helium. was measured with a detector tube 6 (manufactured by Gastec). Table 3 shows the results of measuring the outlet concentration of ammonia. The detection lower limit of the detector tube is 0.5 ppm, and the removal rate in Table 3 was calculated by the formula (1) described in Example 1. Table 3 shows the calculated results.

As is clear from Table 3, the odorant decomposing agent 1 maintained an ammonia removal rate of 80% or more even after continuous exposure to 1000 ppm of ammonia for 46 hours.

(Methyl mercaptan decomposition test 1)
[Example 5]
Using the same fixed-bed flow reactor as in Example 1, evaluation of methyl mercaptan decomposition of odorant decomposing agent 1 was performed by a fixed-bed flow system. As a pretreatment, 50 mg of the odorant decomposing agent 1 was weighed and heated at 150° C. for 2 hours in an air atmosphere using a heating device, and then the reaction tube 5 was filled with the odorant decomposing agent 1 . The reaction tube is not heated, and in a normal temperature atmosphere, helium gas containing methyl mercaptan, which has a methyl mercaptan concentration of 14 ppm, an oxygen concentration of 20 vol%, and the balance is helium, is supplied to gas reservoir 1 at a flow rate of 15.3 mL / min. The concentration of methyl mercaptan in the helium gas containing methyl mercaptan after passing through the odorant decomposing agent 1 was measured with a detector tube 6 (manufactured by Gastech). Table 4 shows the results of measuring the outlet concentration of methyl mercaptan. The detection lower limit of the detector tube is 0.25 ppm, and the removal rate in Table 4 was calculated by Equation 2 below. Table 4 shows the calculated results.
(Formula 2)
Methyl mercaptan removal rate (%) = (methyl mercaptan concentration in gas reservoir 1 - methyl mercaptan concentration measured with detector tube 6) / methyl mercaptan concentration in gas reservoir 1 x 100

[Example 6]
Methyl mercaptan decomposition evaluation was performed in the same manner as in Example 5 except that the odorant decomposing agent 1 was changed to the odorant decomposing agent 2 in Example 5. Table 4 shows the results.

The odorant decomposing agent 2 of Comparative Example 1 had a low removal rate of 7.1% after 11 hours, but the odorant decomposing agent 1 of Example 1 had a removal rate of 40% or more even after 15 hours. maintained.

(Methyl mercaptan decomposition test 2)
[Example 7]
A fixed-bed flow-type reactor shown in FIG. 2 was prepared, and evaluation of decomposition of methyl mercaptan of the odorant decomposing agent 1 and evaluation of the product were carried out by the fixed-bed flow-type. As a pretreatment, 50 mg of the odorant decomposing agent 1 was weighed and heated at 80° C. for 30 minutes under vacuum conditions using a heating device, and further heated at 120° C. for 60 minutes. 1 was filled. The reaction tube is not heated, and nitrogen gas containing methyl mercaptan, which has been adjusted in advance and has a methyl mercaptan concentration of 20 ppm, an oxygen concentration of 20% by volume, and the balance being nitrogen, is circulated from the gas reservoir 1 at a flow rate of 100 mL/min in a room temperature atmosphere. and hydrogen sulfide, sulfur dioxide, dimethyl sulfide and dimethyl disulfide expected as products generated by the reaction of methyl mercaptan in the nitrogen gas containing methyl mercaptan after passing through the odorant decomposing agent 1 and methyl mercaptan and oxygen. was measured by GC-FPD (GC-2014, manufactured by Shimadzu Corporation). Table 5 shows the results of measuring each substance. The lower detection limit for GC-FPD is 0.1 ppm.

[Example 8]
Evaluation of decomposition of methyl mercaptan and evaluation of the product were carried out in the same manner as in Example 7, except that odorant decomposing agent 1 was changed to odorant decomposing agent 3. Table 5 shows the measurement results.

In the measurement after 24 hours, the generation of dimethyl disulfide was confirmed for the odorant decomposing agent 1 of Example 1, but the product could not be confirmed for the odorant decomposing agent 3 of Comparative Example 2. From this, it is considered that the methyl mercaptan adsorbed on the odorant decomposing agent 1 was gradually desorbed from the adsorbed odorant decomposing agent 1 after being converted to dimethyl disulfide. On the other hand, since the odorant decomposing agent 3 does not have a catalytic function, it is presumed that generation of products such as dimethyl disulfide could not be confirmed. As will be described later in another test, when the components adsorbed to the odorant decomposing agent 1 were verified, it was confirmed that sulfuric acid was adsorbed. It is considered that it remains in the substance decomposing agent 1 .

(Methyl mercaptan degradability durability test)
[Example 9]
Using the same fixed-bed flow reactor as in Example 1, a methyl mercaptan decomposition test after exposing the odorant decomposing agent 1 to methyl mercaptan for a long period of time and a methyl mercaptan decomposition test under an elevated temperature heating environment were carried out by a fixed-bed flow system. gone. As a pretreatment, 50 mg of the odorant decomposing agent 1 was weighed and heated at 150° C. for 2 hours in an air atmosphere using a heating device, and then the reaction tube 5 was filled with the odorant decomposing agent 1 . Next, as an accelerated deterioration treatment, helium gas containing methyl mercaptan prepared in advance and having a methyl mercaptan concentration of 80 ppm, an oxygen concentration of 20% by volume, and the balance being helium was supplied to the gas reservoir 1 in a room temperature atmosphere without heating the reaction tube. Accelerated deterioration treatment was performed by circulating for 81 hours at a flow rate of 12.5 mL/min. After that, the composition of the gas was changed to 14 ppm of methyl mercaptan, 20% by volume of oxygen, and the remainder to helium, and the gas was passed through the gas reservoir 1 at the same flow rate. Measure the concentration of methyl mercaptan in the helium gas containing methyl mercaptan after passing through the odorant decomposing agent 1 after 4 hours and 6 hours after switching the gas concentration at 0 hours with a detector tube 6 (manufactured by GASTEC). did. Table 6 shows the results of measuring the outlet concentration of methyl mercaptan. The lower limit of detection of the detector tube 6 is 0.5 ppm, and the removal rate in Table 6 was calculated by Equation 2 described in Example 5 above. Table 6 shows the calculated results.

As is clear from Table 6, odorant decomposing agent 1 was continuously exposed to 80 ppm of methyl mercaptan for 81 hours as an accelerated aging treatment. The removal rate of methyl mercaptan after hours showed 28.6%. From the results in Tables 5 and 6, it was clarified that the odorant decomposing agent 1 has the function of converting methyl mercaptan into another compound through a catalytic reaction, thereby maintaining its decomposing effect.

[Example 10]
(Identification test of methyl mercaptan decomposition products)
Using the same fixed-bed flow reactor as in Example 1, it was verified whether sulfuric acid was adsorbed on the odorant decomposing agent 1 as a decomposition product after decomposition of methyl mercaptan. As a pretreatment, 50 mg of the odorant decomposing agent 1 was weighed and heated at 150° C. for 2 hours in an air atmosphere using a heating device, and then the reaction tube 5 was filled with the odorant decomposing agent 1 . Next, 12.5 mL of helium gas containing methyl mercaptan, which has a methyl mercaptan concentration of 14 ppm, an oxygen concentration of 20% by volume, and the balance being helium, is added to the odorant decomposing agent 1 in a normal temperature atmosphere from the gas reservoir 1. /min for 24 hours to obtain a steady state in which the adsorption of methyl mercaptan by the odorant decomposing agent 1 no longer affects the behavior of removing methyl mercaptan. Furthermore, helium gas containing methyl mercaptan having a methyl mercaptan concentration of 14 ppm, an oxygen concentration of 20% by volume, and the balance being helium was passed through the odorant decomposing agent 1 at a flow rate of 12.5 mL/min for 24 hours from the gas reservoir 1. The gas to be measured was allowed to flow for a total of 48 hours, together with the treatment for establishing a steady state.

For the quantitative determination of sulfuric acid, 2.0 mL of pure water was added to the odorant decomposing agent 1, ultrasonicated for 2 minutes, and left for 30 minutes. After that, centrifugation was performed and the supernatant was extracted. This operation was repeated, and the extracted supernatant was titrated with an aqueous sodium hydroxide solution to determine the concentration of sulfuric acid adhering to the odorant decomposing agent 1 . As a result of quantification, 0.23% sulfuric acid was detected with respect to the total amount of methyl mercaptan removed by the odorant decomposing agent 1. Therefore, it was clarified that the catalytic reaction of the odorant decomposing agent 1 converts methyl mercaptan into sulfuric acid.

Industrial field of application

As is clear from the above results, the odorant decomposing agent of the present invention reacts with ammonia and methylcaptan to decompose these substances even at room temperature, and is therefore considered to maintain its activity.
From the above results, the odorant decomposing agent of the present invention can be used to remove odorous substances containing nitrogen compounds and sulfur compounds generated in toilets, kitchens, trash cans, other living spaces, garbage disposal sites, garbage disposal sites, and livestock farms. It is suitably used for decomposing at room temperature.

1: Gas reservoir 2: Mass flow controller 3: Odor substance decomposing agent 4: Glass wool 5: Reaction tube 6: Detector tube 7: Gas sampling port

Claims

An odorant decomposing agent comprising porous silica having an average pore diameter of 1 nm to 50 nm and a BET specific surface area of 300 to 2000 m 2 /g supporting ruthenium-containing particles having a particle diameter of 1 to 4 nm.
The odorant decomposing agent according to claim 1, wherein the porous silica is mesoporous silica.
The odorant decomposing agent according to claim 1 or claim 2, wherein the amount of ruthenium supported is 0.1 to 10% by mass.
The odorant decomposing agent according to any one of claims 1 to 3, wherein the odorous substance to be decomposed by the odorant decomposing agent is a sulfur compound or a nitrogen compound.
The odorant decomposing agent according to claim 4, wherein the sulfur compound is methyl mercaptan.
The odorant decomposing agent according to claim 4, wherein the nitrogen compound is ammonia.
An odorant-decomposing article comprising the odorant-decomposing agent according to any one of claims 1 to 6.
A method for decomposing an odorous substance, comprising contacting the odorant-decomposing agent according to any one of claims 1 to 6 with an odorant in an atmosphere of 0°C to 50°C or less in the presence of oxygen.