JPH11165038A - Ethylene removing device provided with palladium catalyst and photocatalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and safe ethylene removing device with a simple constitution and enabling to remove harmful substances such as ethylene, ethanol and acetaldehyde generating from plant and keep the quality of the plant for a long period. SOLUTION: The ethylene removing device 1 is provided with a catalyst 2 consisting of a Pd catalyst, a photocatalyst and active carbon. The optical catalyst consists of an anatase-type titanium oxide and at least one optical source selected from an ultraviolet lamp, a black light, a fluorescent light, a LED, and a semiconductor laser is preferred to use as an optical source to the catalyst 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene removing apparatus provided with a Pd catalyst and a photocatalyst, and more particularly, to a method for producing plants when storing vegetables such as vegetables in a storage, a refrigerator, a vending machine, and the like. The present invention relates to a low-cost and safe ethylene removal apparatus capable of removing harmful substances such as ethylene, ethanol, and acetaldehyde that cause physiological disorders in plants and maintaining the quality for a long time.

[0002]

2. Description of the Related Art When preserving plants such as fruits and vegetables, volatile substances such as ethylene (mature and aging hormone), ethanol, and acetaldehyde generated by the plants themselves cause physiological disorders in the plants, resulting in deterioration of freshness and quality. It is known to cause. Ethylene, also called maturation or aging hormone, increases the respiratory action and promotes the reduction of freshness of plants such as horticultural products, as well as the degradation of chlorophyll, the flowering of flowers and the softening of fruits. It is a harmful substance in plant preservation because it significantly reduces it. Ethanol and acetaldehyde are also volatile components produced by plants, and these components themselves are off-flavor components, which not only impair the quality, but also are known as causative substances of physiological disorders such as internal browning of apples.

[0003] For this reason, it is necessary to remove these harmful substances, one utilizing a reaction by a chemical substance such as potassium permanganate, one which is adsorbed and removed by a porous material such as activated carbon, and one which is oxidatively decomposed by ozone. Things are known. However, those resulting from the above-mentioned chemical reaction do not have a long-lasting removal effect, and toxic chemicals are used. Thus, various safety problems such as the risk of accidental eating and disposal problems have not been solved. In addition, the method using an adsorbent or the like has the disadvantage that the adsorbent contains moisture in a high-humidity environment and the adsorbing effect is reduced, is not persistent, and has a problem of releasing the harmful substance once adsorbed. It is known. In addition, the ozone method has the disadvantage that not only does the device become large and the cost increases, but also the effect under low-concentration oxygen conditions such as CA (environmental gas control) storage is reduced, and ozone itself is harmful to the human body. There is also a problem that is.

[0004]

There is a need for an ethylene removal apparatus which overcomes these problems, can safely remove harmful substances such as ethylene at low cost, and can maintain the quality of plants for a long period of time. An object of the present invention is to provide a low-cost and safe ethylene removing device capable of removing harmful substances such as ethylene, ethanol, and acetaldehyde produced by plants and maintaining the quality for a long period of time.

[0005]

According to a first aspect of the present invention, there is provided a catalyst comprising a Pd catalyst, a photocatalyst and activated carbon.

According to a second aspect of the present invention, in the ethylene removing apparatus according to the first aspect, the photocatalyst is made of anatase-type titanium oxide, and a light source for the catalyst is an ultraviolet lamp, a black light, a fluorescent light, LE
D, characterized in that at least one light source selected from semiconductor lasers is used.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the palladium catalyst used in the present invention, various salts of palladium are usually used. Among them, hydrochloride is particularly preferably used. The activated carbon used in the present invention is not particularly limited as long as it is made from a carbonaceous material such as coconut shell, coal, petroleum pitch, oil carbon, and the like. The specific surface area of the activated carbon by the BET method is 400
m ² / g or more, preferably 1000 m ² / g or more.

[0008] The photocatalyst used in the present invention promotes its catalytic reaction by light irradiation. The type of the photocatalyst is not limited.
₂ ), iron oxide (Fe ₂ O ₃ ), tungsten oxide (WO
₃ ), tin oxide (SnO ₂ ), bismuth oxide (Bi ₂ O)
₃ ), nickel oxide (NiO), copper oxide (Cu ₂ O),
Zinc oxide (ZnO), strontium titanate (SrT
n-type and P-type semiconductors such as iO ₃ ), silicon oxide (SiO ₂ ), molybdenum sulfide (MoS ₂ ), indium phosphide (InP), gallium phosphide (GaP), indium lead (InPb), or higher activity Platinum (Pt), rhodium (Ru), niobium (N
b), copper (Cu), tin (Sn), ruthenium oxide (R
Examples thereof include a solid-state photocatalyst of a semiconductor supporting a metal or metal oxide such as uO ₂ ) and nickel oxide (NiO), a ruthenium (Ru) complex such as a ruthenium bipyridyl complex, and a molecular photocatalyst such as porphyrins and chlorofil. In the present invention, one or more of these photocatalysts can be used. Among these, anatase type titanium oxide can be preferably used. As a method for preparing the above-mentioned photocatalyst, in the case of a solid photocatalyst, in the case of a commercially available product, a high-temperature baking of other metal, electrolytic oxidation, chemical vapor deposition, vacuum vapor deposition, coating, coprecipitation, vapor oxidation of metal halide, etc. Can be given as an example.

In the present invention, a catalyst comprising the above Pd catalyst, photocatalyst and activated carbon is used. In the present invention, the mechanism by which harmful components such as ethylene, ethanol, and acetaldehyde are decomposed is not clear, but harmful components such as ethylene adsorbed on activated carbon are oxidized by a Pd catalyst, and ethylene is converted into organic substances such as acetaldehyde and acetic acid. Become. Then, the photocatalyst is activated by receiving light energy of a corresponding wavelength, decomposes the organic matter by a photochemical reaction, and finally, carbon dioxide (CO ₂ ),
It is considered to be a harmless substance such as hydrogen (H ₂ ).
Since the organic matter generated by the oxidation of ethylene or the like by the Pd catalyst is decomposed by the photocatalyst, the ability to oxidize the ethylene or the like by the Pd catalyst can be maintained, and the removal of the ethylene or the like can be performed for a long time.

The method of using each catalyst used in the present invention is not particularly limited. For example, a Pd catalyst may be used as an activated carbon, or a Pd catalyst may be used as an activated carbon, using a known method such as an impregnation method or a spraying method. A catalyst loaded with 0.05 to 10% by weight and a photocatalyst may be used separately, or a mixture of all of them may be used, or a combination thereof may be used.

The light energy of the light irradiation used is to excite the photocatalyst so as to have the ability to decompose organic substances as described above. The light energy has a wavelength corresponding to the excitation of the photocatalyst. It is desirable to irradiate light having a visible wavelength or an ultraviolet wavelength. Examples of the light energy source include a natural light source of sunlight or light emitted from a mercury lamp, light emitted from a filament lamp such as a halogen lamp, short arc cannon light, semiconductor laser beam, ultraviolet lamp, black light, fluorescent light, and blue light.
An artificial light source such as an LED such as an ED or an ultraviolet LED may be used. These may be used in combination of one or more.

The light irradiation method includes a method of irradiating the photocatalyst from outside. In order to increase the intensity of light, light may be collected by a Fresnel lens, a glass lens, or the like, and light energy may be transported by an optical fiber.

The ethylene removing apparatus of the present invention includes, for example, a method in which a predetermined amount is used in a container made of a gas-permeable material such as paper, cloth, nonwoven fabric, etc., which has been subjected to a water-repellent treatment. A method in which air containing toxic substances such as ethylene is introduced into a water-repellent container that contains water and processed, and the processed air is circulated. A method in which plastic powder is mixed as a binder with a catalyst and molded. In a sheet, film, or honeycomb form.

The method for applying the ethylene removing apparatus of the present invention to a storage, a refrigerator, a vending machine, and the like is not particularly limited. Refrigerator, freezer, storage, portable ice box,
It is preferable to use it appropriately according to the type and size of the portable heat-insulating housing and jar, the presence or absence of air circulation and the like.

FIG. 1 is an explanatory view showing one embodiment of the ethylene removing apparatus of the present invention. Ethylene removal device 1 of the present invention
Is a container 3 containing the catalyst 2, a conduit connecting the refrigerator 4 and the container 3, valves 6, 7 and a blower 8 arranged in the conduit, an ultraviolet lamp 9 for exciting the photocatalyst, a dryer 10,
It is composed of valves 11, 12 and the like. The ethylene removing apparatus 1 is configured to introduce air containing harmful substances such as ethylene generated from plants 5 in a refrigerator 4 into a container 3 containing a catalyst 2 by opening valves 6 and 7 and operating a blower 8 to process the air. Then, the processed air is circulated through the container 3. When the catalyst 2 absorbs water, the valves 11 and 12 are opened and hot air is sent from the drier 10 into the vessel 3 for drying and regeneration.
Although the example of FIG. 1 in which the ethylene removing device 1 is disposed outside the refrigerator 4 has been described, the ethylene removing device 1 can be disposed at an appropriate place or position in the refrigerator 4.

[0016]

The present invention will be specifically described below with reference to examples and comparative examples. (Embodiment 1) FIG. 2 is an explanatory view showing a model test example of the ethylene removing apparatus of the present invention. 10 g of the catalyst 2 used in the present invention was placed in a desiccator 13 having a capacity of 12 liters.
4 and 15 were opened, and air containing 60 ppm of ethylene was introduced into the desiccator 13. The valves 14, 15 are then closed,
UV lamp to excite the photocatalyst (Toshiba, 4
W, wavelength 294 nm). Immediately after the ultraviolet irradiation, the valve 15 is opened for 300 minutes at every elapse of time to sample the air in the desiccator 13 to determine the ethylene content by gas chromatography (column Porap).
ak-Q, FID). The results are shown in FIG. Ethylene decreased in a short time, and no organic substances such as acetaldehyde and acetic acid were detected.

(Comparative Example 1) A test was conducted in the same manner as in Example 1 except that the catalyst 2 of Example 1 was replaced with activated carbon impregnated with a Pd catalyst (manufactured by Kuraray Chemical Co., Ltd., 1% activated carbon impregnated with a Pd catalyst). The results are shown in FIG. Ethylene decreased in a short time,
Organic substances such as acetaldehyde and acetic acid were detected.

Comparative Example 2 A test was conducted in the same manner as in Example 1 except that the catalyst 2 of Example 1 was replaced with a photocatalyst (ST-31, manufactured by Ishihara Sangyo Co., Ltd.). FIG. 4 shows the results. Approximately 20 ppm of ethylene remains even after 24 hours, and the ethylene removing effect is low.

(Comparative Example 3) Catalyst 2 of Example 1 was replaced with (photocatalyst + type 230 activated carbon) [Itahara Sangyo Co., Ltd. photocatalyst ST-31: type 230 activated carbon (copper catalyst 2%, Mn
Activated carbon containing 3% catalyst) = 1: 1 (manufactured by Kuraray Chemical)
The test was performed in the same manner as in Example 1 except that the test was replaced with FIG. 5 shows the results. About 20 ppm of ethylene even after 24 hours
It remains and has a low ethylene removal effect.

Incidentally, since the present invention is not limited to the above-described embodiment, various modifications can be made without departing from the spirit of the present invention.

[0021]

According to the ethylene removing apparatus of the present invention, harmful substances such as ethylene, ethanol, and acetaldehyde generated by plants can be removed to maintain the quality of plants for a long period of time. The ethylene removing apparatus of the present invention has a simple configuration, is low in cost, and can safely and continuously remove harmful substances such as ethylene, ethanol, and acetaldehyde, and thus has high industrial utility value.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of an ethylene removing device of the present invention.

FIG. 2 is an explanatory diagram showing a model test example of the ethylene removing device of the present invention.

FIG. 3 is a graph showing the relationship between ethylene concentration and elapsed time.

FIG. 4 is a graph showing the relationship between ethylene concentration and elapsed time.

FIG. 5 is a graph showing the relationship between ethylene concentration and elapsed time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ethylene removal apparatus 2 Catalyst 3 Container 4 Refrigerator 5 Plant 8 Blower 9 Ultraviolet lamp 13 Desiccator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI A23L 3/3445 A23L 3/3445

Claims (2)

[Claims] 1. An ethylene removing device comprising a catalyst comprising a Pd catalyst, a photocatalyst and activated carbon. 2. The photocatalyst comprises anatase type titanium oxide, and at least one light source selected from an ultraviolet lamp, a black light, a fluorescent lamp, an LED and a semiconductor laser is used as a light source for the catalyst. The ethylene removing device according to claim 1, wherein