JP2569984B2 - Hazardous substance remover and harmful substance removal method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agent for removing harmful substances such as malodorous substances, pungent odorous substances or horticultural crop growth promoting substances, a method for producing the same, and a method for removing harmful substances using the same.

[0002]

2. Description of the Related Art In recent years, not only bad odors and pungent odors generated industrially, but also odors of wastes in homes and restaurants or bad odors and pungent odors generated during cooking have become a problem. The main components of these odors are hydrogen sulfide, ammonia,
Mercaptans, amines, aldehydes and the like. Also,
Demand for fresher supplies or supplies outside of the original harvest season for fruits and vegetables, etc. has increased, and in order to keep these horticultural crops fresh,
There is a need for an efficient method for removing growth promoting substances such as ethylene, which is a plant growth hormone. Conventionally, methods for removing these harmful substances include (1) activated carbon, alumina,
(2) a method of neutralizing acidic (or basic) harmful substances with a basic (or acidic) substance; (3) a method of neutralizing acidic (or basic) harmful substances with a basic (or acidic) substance; A method of chemically oxidizing with chlorine or the like is known. However, these methods are not always satisfactory. That is, the method (1) does not have a sufficient ability to adsorb a basic substance such as ammonia or the like and ethylene, the method (2) has limited harmful substances depending on the compound used, and the method (3) does not. Speed is slow.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method which does not have the above-mentioned drawbacks and which simultaneously removes various harmful substances efficiently. Another object of the present invention is to provide a novel harmful substance remover used therefor and a method for producing the same.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to achieve this object, and as a result, a solid product obtained by hydrolyzing a metal alkoxide has excellent harmful substance removal performance. And found that the present invention was completed based on this finding. Thus, according to the present invention, there is provided a solid product obtained by hydrolyzing a metal alkoxide in the presence or absence of a noble metal, wherein the solid product has a specific surface area of 100 m ² / g or more. Substance removing agent; a solid product obtained by hydrolyzing a metal alkoxide in the presence or absence of a noble metal;
A method for producing the above harmful substance removing agent, characterized by drying at a temperature of less than 00 ° C; and a method for removing harmful substances, comprising using this harmful substance removing agent.

[0005] In the present invention, the metal alkoxide used as a raw material of the harmful substance remover (hereinafter sometimes simply referred to as a remover) is not particularly limited depending on the composition and production method as long as it is a metal alcohol ester. In general, it is known that metal alkoxides can be prepared from most metals listed in the Periodic Table of the Elements ("Industrial Materials", Vol. 29, No. 5, pp. 85-89, 19).
1989, published by Nikkan Kogyo Shimbun), from the viewpoint of being chemically stable and easily available, the short-period type periodic tables IIa, IIb,
Alkoxides of elements IIIa, IIIb, IVa, IVb, Va, Vb and VIII, especially IIb, II
Preference is given to Group Ia, IIIb, IVa, IVb elements, especially alkoxides of aluminum, silicon, titanium, zinc and zirconium. The alcohol component of the metal alkoxide is not particularly limited, but preferably has 1 to 4 carbon atoms from the viewpoint of easy hydrolysis of the metal alkoxide and easy removal of alcohol generated by the decomposition.
In the present invention, a metal alkoxide composed of two or more metals can be used as the metal alkoxide.
Further, two or more kinds of metal alkoxides may be used in combination.

The method of hydrolyzing the metal alkoxide in the present invention is not particularly limited, and water may be added to the metal alkoxide, or a method of charging the metal alkoxide into water may be used. In these methods, the metal alkoxide can be added to the reaction system as it is or in a state of being dissolved or dispersed in a solvent, but it prevents abrupt reaction and produces fine hydrolysis products having a uniform particle size. In order to obtain, it is preferable to use it after dissolving it in a solvent. Further, a mixed solution of water and alcohol may be used instead of water, and the water or the mixed solution of water and alcohol may be used in a state of being mixed with a solvent. Further, the water or the water-alcohol mixture may be previously adjusted to be acidic or alkaline with an acidic or alkaline substance in order to promote hydrolysis of the metal alkoxide. The solvent used in these methods may be either an inorganic compound or an organic compound, but from the viewpoint of solubility in the metal alkoxide, the same alcohol as used in the synthesis of the metal alkoxide is preferable, and the solvent used in the drying step is not removed. From the viewpoint of easiness and ease of handling, those having a boiling point of 200 ° C or lower, more preferably those having a boiling point of 150 ° C or lower are used. Specific examples of these solvents include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, and amyl alcohol; aromatic hydrocarbons such as benzene, toluene, xylene, and the like; hexane, heptane, and the like. Such chain hydrocarbons can be shown.

In the present invention, a metal alkoxide is hydrolyzed in the presence of a noble metal, whereby a harmful substance remover having better performance can be obtained. The noble metal used in the present invention is a noble metal element selected from gold, silver, copper and a platinum group element (ruthenium, rhodium, palladium, osmium, iridium and platinum) and a compound containing these noble metals. Examples of the compound containing a noble metal include an oxide, a chloride, and a complex, but are not limited thereto. These noble metals may be present in the reaction system during hydrolysis of the metal alkoxide. Specifically, (1) a method in which a noble metal is dissolved or dispersed in advance in a solvent used in the hydrolysis, water or a water-alcohol mixture, and (2) a method in which the noble metal is previously mixed with a metal alkoxide. A method of hydrolyzing a metal alkoxide, (3) a method of adding a noble metal to a system simultaneously with hydrolysis, and the like can be employed. These noble metals are preferably used in a state of being dissolved in a solvent in order to uniformly disperse them in the hydrolysis product of the metal alkoxide. The amount of the noble metal used in the present invention is not particularly limited, but is preferably 10% by weight or less of the metal alkoxide. If the amount of the noble metal is too large, it will not be uniformly mixed with the hydrolysis product of the metal alkoxide, and the harmful substance removal performance will be reduced.

After hydrolysis of the metal alkoxide, the hydrolysis product is separated from the solvent or reaction by-products by a method such as filtration, decantation or evaporation to dryness. In order to improve the harmful substance removal performance by removing the solvent and the generated alcohol and the like attached to the hydrolysis product, this is usually performed at a temperature lower than 300 ° C, preferably 60 to
Drying at 250 ° C. gives a solid product. Of course, it may be dried at room temperature, but it takes a long time. If the drying temperature is 300 ° C. or higher, the harmful substance removing performance is undesirably reduced. The cause is not clear because the mechanism of action of the harmful substance removing agent of the present invention has not been elucidated, but it is considered that the specific surface area of the hydrolysis product rapidly decreases at 300 ° C. or higher. The time required for drying is not particularly limited, and the time when the weight loss substantially disappears may be determined as the end point of the drying, and is usually 1 to 10 hours. Drying may be performed in air, and need not be performed in an inert gas atmosphere. Further, drying under normal pressure or drying under reduced pressure or vacuum may be used. There is no particular limitation on the heating method for drying, but heating with electricity, steam, hot (hot) water, or electromagnetic waves that can uniformly and stably obtain a constant temperature for practical use is preferable.

The harmful substance removing agent of the present invention has a specific surface area of at least 100 m ² / g as measured by the BET method. Even if the specific surface area is less than 100 m ² / g, harmful substances can be removed, but the removal rate is slow and not practical.

In the present invention, a solid product obtained by drying a hydrolysis product of a metal alkoxide at a temperature lower than 300 ° C. can be used alone as it is. It may be used by being supported on a catalyst carrier made of a porous body of an inorganic substance such as glass or glass, a porous body made of an organic polymer substance, woven fabric, nonwoven fabric, fiber, paper, or the like. Further, the adsorbent, the porous body, or the like may be used after being subjected to a secondary processing into a honeycomb shape, a sponge shape, or a more complicated shape before or after processing. Examples of adsorbents include activated carbon, natural zeolites,
Artificial zeolite, alumina, silica gel, allophane,
Examples of the catalyst carrier include silica, silica alumina, silicon carbide, titania, zirconia, magnesia, cordierite, and mullite. Examples of the organic polymer substance include homopolymers such as polyethylene, polypropylene, polyvinyl chloride, polyester, polystyrene, and polytetrafluoroethylene, acrylonitrile-butadiene-styrene copolymer (ABS), and acrylonitrile-methyl acrylate. Copolymers such as copolymers, ethylene-tetrafluoroethylene copolymer (ETFE), and ethylene-vinyl acetate copolymer are exemplified.

Further, when removing a large amount of harmful substances or removing harmful substances in a short time, a reactor filled with the harmful substance removing agent is used as a fixed bed or a fluidized bed, or the harmful substance removing agent is used. It is preferable to improve the contact efficiency between the removing agent and the harmful substance by using the filter as a filter carrying the compound. When used as a fixed bed or a fluidized bed, the reactor is preferably made of a ceramic, glass or organic polymer whose at least a part of its outer wall is not permeable to the removing agent but is permeable to harmful substances or fluids containing it. It is formed of a porous body, woven fabric, nonwoven fabric, fiber, or the like made of a substance. When used as a filter, it is preferable that various adsorbents, porous bodies, and the like are supported on a carrier that can be subjected to secondary processing into various shapes such as a honeycomb shape and a sponge shape.

The method for removing various harmful substances using the harmful substance remover of the present invention is not particularly limited. As a specific example, a method of introducing a harmful substance or a gas containing the harmful substance into an open system or a closed system reactor containing a removing agent in a batch system or a continuous system can be shown.

[0013] The harmful substance removing agent of the present invention can be repeatedly regenerated and used. As a method of reproduction, 30
There is a method of heating at a temperature lower than 0 ° C., a method of irradiating electromagnetic waves such as ultraviolet rays, visible light or infrared rays, a method of contacting with ozone, a method of irradiating ultrasonic waves, and the like. If it is, there is no particular limitation.

In the present invention, the removal efficiency can be increased by removing the harmful substance under ultraviolet irradiation. The ultraviolet light used in the present invention is preferably near ultraviolet light having a wavelength of 400 to 200 nm.
m or less may be included. These ultraviolet rays can be generated by using an ultra-high pressure mercury lamp, a xenon lamp, or a low-pressure mercury lamp alone or in combination,
A light source improved to have a wavelength distribution characteristic suitable for the purpose by using a third component such as gallium or thallium in addition to mercury and a rare gas in the discharge tube may be used.
Further, light rays other than ultraviolet rays, for example, visible light rays may be included. The installation place of the ultraviolet lamp used in the present invention is not particularly limited as long as the solid product can be efficiently irradiated. When used for irradiation in a fluidized bed or fixed bed, irradiation may be performed from the outside of the reactor. However, in order to perform irradiation efficiently, it is preferably installed inside the reactor.

[0015]

The present invention will be described below in more detail with reference to examples and comparative examples. Unless otherwise specified, parts and%
Is based on weight.

Example 1 (Experiment Nos. 1 to 3) 6 g of each of the various metal alkoxides shown in Table 1 (liquid was used as it is, solid was dissolved in 60 g of n-hexane and used) was stirred. Meanwhile, 1 g of ion-exchanged water was gradually dropped therein to perform hydrolysis. The obtained precipitate was filtered through a glass filter, and then at 60 ° C. for 8 hours.
Preliminary drying with a vacuum dryer, and at normal pressure, 200 ° C for 1 hour
After drying for a period of time, a powdery harmful substance remover was obtained. Next, 1 g of the obtained remover was put into an 80 ml ultraviolet transparent glass conical flask, and the inside of the flask was replaced with air containing the initial concentration of ethylene shown in Table 1, and then sealed with a silicone rubber stopper. The change over time in the concentration of ethylene in the container was followed by gas chromatography. Table 1 shows the results.

[Comparative Example 1 (Experiment Nos. 4 to 6)] The same experiment as in Example 1 was performed except that the temperature for normal-pressure drying was 400 ° C. The results are shown in Table 1.

Comparative Example 2 (Experiment Nos. 7 to 9) Example 1 was repeated using activated carbon honeycomb molded articles, potassium permanganate, and 1 g each of titanium dioxide, which are commercially available deodorants.
The same evaluation was performed. The results are shown in Table 1.

[0019]

[Table 1]

From the results shown in Table 1, it can be seen that the harmful substance remover of the present invention is much more excellent in ethylene removal performance than typical commercially available deodorants. In addition, the specific surface area is 100
When it is smaller than m ² / g, it can be seen that the ethylene removal performance decreases.

Example 2 (Experiment Nos. 10 to 13) The same experiment as in Example 1 was performed except that a 10% aqueous solution of a noble metal shown in Table 2 was used in place of ion-exchanged water. Table 2 shows the results.

[0022]

[Table 2]

From the results in Table 2, it can be seen that the removing agent obtained by hydrolyzing the metal alkoxide in the presence of the noble metal has more excellent ethylene removing performance.

[Example 3 (Experiment Nos. 14 to 16)] Using the remover prepared from titanium tetraisopropoxide and silver nitrate in the same manner as in Example 2, the test was carried out on harmful substances in the air shown in Table 3. The same experiment as in Example 1 was performed. Table 3 shows the results.

[0025]

[Table 3]

From the results shown in Table 3, it can be seen that the harmful substance removing agent of the present invention is effective for removing various harmful substances.

Example 4 (Experiment Nos. 17 to 20) 9 g of each of the titanium alkoxides shown in Table 4 was placed in an enamel vat having a length of 15 cm, a width of 15 cm and a depth of 2 cm, and 1
An electrostatic non-woven fabric of 0 cm × 10 cm was impregnated and thoroughly permeated. The nonwoven fabric was taken out and sprayed with ion-exchanged water by hand spraying. Then, this is
After predrying with a vacuum dryer at 8 ° C for 8 hours,
After drying at 0 ° C. for 1 hour, an electrostatic nonwoven fabric carrying a harmful substance removing agent was obtained. A 1 cm × 5 cm sample piece was prepared from the obtained electrostatic nonwoven fabric, and two pieces (the total amount of the harmful substance removing agent carried on the two sample pieces was 0.8 g) were 8 pieces.
The flask was placed in a 0 ml ultraviolet transparent glass Erlenmeyer flask, the inside of which was replaced with air containing the initial concentration of ethylene shown in Table 4, sealed with a silicone rubber stopper, and placed at a distance of 20 cm from the flask. High pressure mercury lamp (Illuminance 1
UV irradiation was performed at 0 mW / cm ² and a main wavelength of 365 nm. The change over time in the ethylene concentration in the container after the mercury lamp was turned on was tracked by gas chromatography. Table 4 shows the results. The same experiment was performed except that ultraviolet irradiation was not performed. The results are shown in Table 4.

Comparative Example 3 (Experiment Nos. 21 to 22) The same experiment as in Example 4 was carried out using 1 g each of silver-supported zeolite (trade name: Bactekiller, manufactured by Kanebo) or titanium dioxide, which is a commercially available deodorant. . The results are shown in Table 4.

[0029]

[Table 4]

From the results shown in Table 4, it can be seen that ethylene can be rapidly removed by the method of the present invention, whereas the removal rate in Comparative Example 3 is low.

Example 5 (Experiment Nos. 23 and 24) While stirring a mixture of 50 ml of n-hexane, 10 ml of ethanol and 10% aqueous silver nitrate, 14 g of titanium tetraisopropoxide was added to the mixture. A solution obtained by dissolving in 50 ml of hexane was slowly dropped from a dropping funnel. The resulting precipitate was collected by filtration with a glass filter, pre-dried at 60 ° C. for 8 hours with a vacuum dryer, and then dried at normal pressure and 200 ° C. for 1 hour to obtain a harmful substance remover. Example 4 using 1 g of this remover
The same experiment was performed. The same experiment was performed except that palladium nitrate was used instead of silver nitrate. The results are shown in Table 5.

[0032]

[Table 5]

Example 6 (Experiment Nos. 25 to 27) Using the harmful substance removing agent prepared from titanium tetraisopropoxide and silver nitrate in the same manner as in Example 5, the harmful substances in the air shown in Table 6 were used. The same experiment as in Example 5 was performed for Table 6 shows the results. This indicates that various harmful substances can be rapidly removed by the method of the present invention.

[0034]

[Table 6]

Example 7 (Experiment Nos. 28 to 29) 7 g of zinc chloride was dissolved in isopropanol which had been dehydrated with a molecular sieve. Ammonia gas was bubbled through the glass tube for 1 hour under ice-cooling. After removing ammonia gas from the obtained solution with an evaporator, a supernatant was obtained by centrifugation. 10 ml of ion-exchanged water is dropped into the supernatant,
The resulting precipitate was collected by filtration with a glass filter, pre-dried at 60 ° C. for 8 hours with a vacuum dryer, and then dried at normal pressure at 200 ° C.
For 1 hour to obtain a harmful substance remover. The same experiment as in Example 5 was performed using this remover. Table 7 shows the results
Shown in

[0036]

[Table 7]

Example 8 Thirty commercially available kiwis were placed in a desiccator having an internal volume of 12 liters, which was installed in a low-temperature thermostat. A solid product prepared from this desiccator and titanium tetraisopropoxide and silver nitrate as in Example 2. 5.
A 300 ml photochemical reaction flask and a diaphragm type air pump, which are charged so that a low-pressure mercury lamp (illuminance: 3 mW / cm ² , main wavelength: 254 nm) can be irradiated with the harmful substance removing agent, and a diaphragm type air pump in this order, Connected with. The components other than the desiccator were installed outside the low-temperature thermostat. Then, the desiccator was heated at a temperature of 10
After maintaining the temperature at 90 ° C. and the humidity at 90% or more, the internal air was circulated by a diaphragm type air pump [Experiment A (Example of the present invention)]. In addition, a similar experiment was performed without performing ultraviolet irradiation [Experiment B (Example of the present invention)]. Further, for comparison, the same experiment was performed except that the removing agent of the present invention was not used [Experiment C (Comparative Example)]. At the start of the air circulation, no ethylene and acetaldehyde were detected in the desiccator for any of experiments A, B and C. In experiments A and B, none of these could be detected after 4 weeks and 60 days,
In experiment C, after 4 weeks, 7 ppm of ethylene and 2 p
After 60 days, 15 ppm of ethylene and 4 ppm of acetaldehyde were detected. The concentrations of ethylene and acetaldehyde were measured by gas chromatography. When the sugar content of the kiwi was measured with a refractometer (manufactured by Atago Co., Ltd.), four weeks later,
In Experiments A and B, the sugar content was 16 and was not different from 17 before the start of the experiment, whereas in Experiment C, the sugar content was 16 to 1
Had dropped to 2. Furthermore, in Experiment C, the skin was generally softer, wrinkled and wrinkled as compared with Experiments A and B, and of these, six juices partially leaked out. From these results, it is understood that the method of the present invention is effective in maintaining the freshness of horticultural crops.

Example 9 A UV-transparent glass cylindrical reaction tube having an inner diameter of 35 mm and a length of 300 mm having an inlet and an outlet having an inner diameter of 5 mm and a length of 40 mm at both ends through a glass filter was placed in a cylindrical reaction tube.
In the same manner as in Example 2, 10 g of a harmful substance remover prepared from titanium tetraisopropoxide and silver nitrate was added. Next, the reaction tube was held vertically, and air containing ethylene, methyl mercaptan, trimethylamine or formaldehyde having a concentration of about 100 ppm was supplied from the lower leg of the reaction tube at a rate of 0.5 to 10 liter / hour.
The removal agent of the present invention was introduced at a flow rate of 1 minute, and was allowed to flow out from the upper leg portion of the reaction tube so that a part or all of the removing agent of the present invention floated. The concentrations of various harmful substances in the effluent gas were measured by gas chromatography, and all were below the detection limit. This shows that when the harmful substance removing agent of the present invention is used in a fluidized bed, a remarkable harmful substance removing effect can be obtained.

Example 10 (Experiment No. 30) 1 g of a harmful substance remover prepared from titanium tetraisopropoxide and silver nitrate in the same manner as in Example 2 was put into an 80 ml ultraviolet-transparent glass conical flask. Then, after the inside was replaced with air containing 10000 ppm of ethylene, it was sealed with a silicone rubber stopper and left for 8 hours. Thereafter, the silicone rubber stopper was removed, the flask was opened, and the flask was allowed to stand for 1 hour to allow ethylene remaining in the flask to evaporate. Next, an ultra-high pressure mercury lamp (illuminance: 10 mW / cm ² , principal wavelength: 365) set at a distance of 20 cm from the flask
nm), irradiation of the harmful substance removing agent was performed for 2 hours. Next, the inside of the flask was replaced with air containing ethylene at a concentration of about 100 ppm, and the flask was sealed with a silicone rubber stopper. The same experiment as in Example 1 was performed. Table 8 shows the results.
Shown in

Comparative Example 4 (Experiment No. 31) The same experiment as in Example 10 was performed, except that ultraviolet irradiation after ethylene emission was not performed. The results are also shown in Table 8.

[0041]

[Table 8]

From the results shown in Table 8, it can be seen that the harmful substance removing agent of the present invention can be reused repeatedly.

[0043]

Thus, according to the present invention, harmful substances such as malodorous substances, irritating odorous substances, or horticultural crop growth promoting substances can be removed quickly and efficiently compared to the prior art. Further, the method of the present invention is a method suitable for removing high-concentration harmful substances, because the method can be repeatedly reused even after the harmful substance removing agent is saturated with the harmful substances.

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Claims (5)

(57) [Claims] 1. Removal of harmful substances, which is a solid product obtained by hydrolyzing a metal alkoxide in the presence or absence of a noble metal, having a specific surface area of 100 m ² / g or more. Agent. 2. The metal alkoxide of the short periodic table II
a, IIb, IIIa, IIIb, IVa, IVb, V
The harmful substance remover according to claim 1, which is an alkoxide of a, Vb or VIII element. 3. The harmful substance-removing agent according to claim 1, wherein a solid product obtained by hydrolyzing the metal alkoxide in the presence or absence of a noble metal is dried at a temperature lower than 300 ° C. Manufacturing method. 4. A method for removing harmful substances, comprising contacting a harmful substance with the harmful substance removing agent according to claim 1. 5. A method for removing harmful substances, comprising contacting a harmful substance with the harmful substance removing agent according to claim 1 under ultraviolet irradiation.