JPH06304480A - Photocatalytic lamp for decomposing ethylene and device for decomposing ethylene - Google Patents

Abstract

PURPOSE:To provide a photocatalytic lamp for decomposing ethylene which has extremely high decomposition capacity of ethylene through light although the manufacturing method of the photocatalytic lamp is simple and the same is inexpensive. CONSTITUTION:This photocatalytic lamp for decomposing ethylene is manufactured by using a binder wherein penetrability of light is excellent and carrying the fine grains of titanium oxide having crystal grain diameter of 100-500 angstrom on the surface of a lamp for a light source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene decomposition photocatalyst lamp in which titanium oxide fine particles are carried on an ultraviolet lamp for decomposing ethylene generated by the progress of the breathing action of fruits and vegetables, and further the catalyst thereof. Relates to an ethylene cracking device.

[0002]

2. Description of the Related Art Ethylene gas is generated as the respiration of fruits and vegetables progresses, and the action of ethylene gas accelerates the maturity and aging of fruits and vegetables, resulting in poor shelf life. Therefore, in order to maintain the freshness of fruits and vegetables after harvesting during transportation or storage, it is preferable to efficiently remove ethylene gas generated from these. As a method of maintaining freshness of fruits and vegetables during storage, a method of removing ethylene gas with an adsorbent such as activated carbon or zeolite and a method of decomposing and removing with an oxidation catalyst are widely used. However, since fruits and vegetables are generally stored in a state of high humidity and high concentration of carbon dioxide, it is difficult to remove ethylene gas by adsorption by the method using an adsorbent due to the effect of coexisting water and carbon dioxide. Further, since adsorbed ethylene may be desorbed, it cannot be expected to maintain sufficient ethylene removal efficiency by the adsorption method. In addition, there is a disadvantage that the adsorbent must be frequently replaced in order to maintain the ethylene removal performance. On the other hand, as a catalyst for decomposing and removing ethylene gas, for example, Japanese Patent Application Laid-Open No. 2-312541 discloses a preservative in which potassium permanganate is supported on activated alumina, but potassium permanganate has an ethylene removing performance. Although excellent, it is a poisonous substance and has problems in its disposal. Further, Japanese Patent Laid-Open No. 63-63339 discloses a freshness-retaining agent made of activated carbon having palladium and / or palladium chloride and sulfuric acid attached thereto. However, the freshness-retaining agent can be heated by heating means such as a heater. Since it needs to be heated, it may adversely affect the freshness of fruits and vegetables. Japanese Unexamined Patent Publication No. 1-252244 discloses a freshness-keeping method and device for keeping a freshness of an agricultural product by irradiating a powdery photocatalyst containing titanium oxide with light to excite it to decompose ethylene. However, further improvement in ethylene removal performance is expected.

JP-A-1-293876 and JP-A-1-139139 disclose a deodorizing / sterilizing device in which a cylindrical body whose inner surface is coated with a photocatalyst is coaxially installed so as to surround a tubular ultraviolet light source. It is disclosed. Further, JP-A-2-280818 discloses a deodorizing method using a photocatalyst which decomposes a malodorous component in the atmosphere by irradiating a semiconductor catalyst with ultraviolet rays having a wavelength of 250 nm and an ultraviolet intensity of 2.0 mW / cm ² or more. It is taught that the semiconductor catalyst is used by being applied to the surface of the light source, or provided with a support around the light source and applied or impregnated with it. , Not disclosed. However, the inventions of JP-A-1-293876, JP-A-1-139139, and JP-A-2-280818 are all inventions relating to deodorization, not to decomposition and removal of ethylene, and to deodorization. There is no connection with ethylene decomposition.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an ethylene decomposition photocatalytic lamp which has a very high ethylene resolution by light, though the manufacturing method is simple and inexpensive. In point.

[0005]

[Structure] The present inventor has researched and developed a method of maintaining freshness by using a photocatalyst to decompose ethylene generated as the respiration of fruits and vegetables progresses. As a result, the method of irradiating the photocatalyst with light to decompose ethylene Even if a photocatalyst is formed by providing a catalyst coating layer on the outer peripheral surface of a light source lamp that supplies energy to the photocatalyst, it is confirmed that ethylene diffuses well into the catalyst coating layer and a decomposition reaction occurs. It was found that the ethylene resolution can be further improved by providing a reflector around the ethylene to complete the ethylene decomposition photocatalytic lamp and the ethylene decomposition device.
That is, the first aspect of the present invention is that an ethylene decomposition photocatalyst lamp is characterized in that fine particles of titanium oxide having a crystal particle size of 100 to 500 angstrom are carried on the surface of a light source lamp by using a binder having a good light transmission property. Regarding

One component of the ethylene decomposition photocatalyst lamp of the present invention is a photocatalyst component, which is titanium oxide as a metal oxide semiconductor photocatalyst. The crystal particle size of titanium oxide is 1
00-500 angstrom, preferably 150-3
The one having a thickness of 00 angstrom has a particularly excellent ethylene resolution by light. The amount of the photocatalyst component supported depends on the intensity of the light source, but the total area of the light source (c
The amount is 0.1 mg or more per m ² (converted into the thickness of the catalyst layer of 1 μm or more), preferably 0.2 mg or more (converted into the thickness of the catalyst layer of 2 μm or more). When a reflector is installed at a distance around the ethylene decomposition photocatalyst,
When the amount of the photocatalyst component supported is about 0.5 mg / cm ² , the ethylene resolution is maximized. The binder is preferably a silica-based binder having good light transmittance, and is used in an amount of 10 to 30% by weight of the catalyst component. The light source lamp may be any one that photochemically excites titanium oxide,
Has a bandgap of 3.2 eV or more and a wavelength of 388
It is preferably an ultraviolet lamp that emits ultraviolet rays of nm or less and supplies light energy to the catalyst component.

Titanium oxide fine particles having a crystal particle size of 100 to 500 angstroms, preferably 150 to 300 angstroms, and 10 to 10 parts by weight of titanium oxide.
A 30% binder and water are mixed to prepare a slurry liquid, and the slurry liquid is applied to the outer peripheral surface of the quartz tube of the ultraviolet lamp and dried to form a catalyst coating layer. As a method for applying to the outer peripheral surface of the ultraviolet lamp, existing methods such as a dipping method and an air spray method can be simply and efficiently applied.

A second aspect of the present invention relates to a device for decomposing ethylene by light, which comprises an ethylene decomposing photocatalyst lamp in which titanium oxide fine particles are carried on the surface of a light source by using a binder having a good light transmitting property, and the above ethylene. The present invention relates to an ethylene decomposing device comprising a reflector surrounding a decomposition photocatalyst lamp with a distance and a means for introducing an ethylene-containing gas into a space between the ethylene decomposition photocatalyst lamp and the reflector. The reflector may be any one as long as it has a high light reflection efficiency, but preferably a mirror-treated metal, a mirror or the like can be used.

[0009]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 To a solution prepared by adding 10 g of 60 wt% concentrated nitric acid to 4000 g of ion-exchanged water, 1000 g of Snowtex-0 (manufactured by Nissan Kagaku Kogyo Co., containing 20% of SiO ₂ ) was added and mixed as a binder. To this solution, 1000 g of titanium dioxide powder P-25 manufactured by Nippon Aerosil Co., Ltd. was added while mixing with a turbo mixer, and 3.3% by weight of SiO ₂ and TiO ₂ were added.
6000 g of a slurry solution containing 16.7% by weight of was obtained. 6W Toshiba GL-6 UV germicidal lamp that emits ultraviolet rays with a wavelength of 254 nm (tube length 210 mm, tube diameter 1
The slurry solution was uniformly applied to a quartz tube (length 150 mm) in the discharge part (5 mm) by an air spray method, and then dried at a temperature of 150 ° C. for 3 hours to obtain TiO ₂ and Si.
0.067mg / cm ² , 0.18mg in total with O ₂
/ Cm ² , 0.46 mg / cm ² , 0.8 mg / cm ² and 1.8 mg / cm ² were respectively carried to obtain ethylene photocatalyst lamps A, B, C, D and E. Ethylene resolvability evaluation test 1 A sample ethylene photocatalyst lamp was placed, and 1.6 ml of 99.6% ethylene was injected into a 16-liter glass case in which a fan for circulation of the atmosphere was installed in the lower part, and the inside of the glass case was injected. Ethylene concentration was adjusted to 100 ppm. After installing the sample catalyst, in order to see the ethylene adsorption performance of the sample catalyst, the change in ethylene concentration was measured without first turning on the lamp by circulating the atmosphere with a fan for the first ten minutes. It was found that ethylene remained unchanged and was not adsorbed on the sample ethylene photocatalytic lamp. After 10 minutes, the ethylene photocatalyst lamp was turned on, and the ethylene concentration was measured 90 minutes after the lighting. The results are shown in Table 1.

[0010]

[Table 1] Type of catalyst Supported amount Thickness of catalyst coating layer Residual 90 minutes after irradiation (mg / cm ² ) (μm) Ethylene concentration (ppm) A 0.07 0.7 97.2 B 0.18 1 4.8 47.0 C 0.46 4.6 49.6 D 0.80 8.0 51.6 E 1.82 18.2 48.8 From Table 1, the ethylene photocatalyst lamps B, C, D of the present invention are shown. It was also proved that and E had an extremely excellent ethylene decomposing ability, and it was also found that the ethylene decomposing ability becomes almost constant when the supported amount of the catalyst is about 0.2 mg / cm ² or more. Example 2 A 150 mm × 173 mm aluminum sheet was used for a diameter of 5
A hollow cylindrical reflector having a length of 5 mm and a length of 150 mm was formed, and the ethylene photocatalyst lamps A and B of Example 1 were mounted on the central axis thereof.
C, D and E are installed, the above ethylene resolution evaluation test 1 is performed, and the results are shown in Table 2.

[Table 2] Type of catalyst Supported amount Catalyst coating layer thickness 90 minutes after UV irradiation (mg / cm ² ) (μm) Leakage amount (mw / cm ² ) Ethylene concentration (ppm) A 0.070 .7 6.0 96.4 B 0.18 1.8 1.9 13.7 C 0.46 4.6 0.08 7.2 D 0.80 8.0 0.04 9.6 E 1. 82 18.2 0.01 24.1 From Table 2, it is proved that the ethylene photocatalyst lamps B, C, D and E of the present invention have further excellent ethylene decomposing ability by attaching the reflecting plate, and the catalyst loading amount is , About 0.5 mg / cm ² shows the highest ethylene resolution. Further, by converging a small amount of ultraviolet energy (wavelength 220 to 290 nm) that permeates and leaks through the catalyst coating layer to the catalyst coating layer again by the reflection plate, it is clear from the comparison between Table 1 and Table 2 that the ethylene resolution is one digit. It was improved and the breakthrough ethylene resolution was achieved.

Comparative Example 1 The inner surface of the reflector used in Example 2 had the same area as the catalytic coating area of the ethylene photocatalyst lamp, that is, 47 mm in length.
The slurry solution of Example 1 was applied to a width of 150 mm, and then 1.6 mg / cm ² , 2.8 mg was applied in the same manner as in Example 1.
/ Cm ² and 3.7 mg / cm ² of tubular sheet catalysts X, Y and Z were prepared. Ethylene resolution evaluation test 2 A 6 W Toshiba germicidal UV germicidal lamp (GL-6) that emits ultraviolet rays having a wavelength of 254 nm (a catalyst layer is not formed on the surface of this light source lamp) was mounted on Comparative Example 1. 1.6 ml of 99.6% ethylene was injected into a 16-liter glass case, which was placed on the central axis of a cylindrical sheet catalyst and mounted on the lower part of which a fan for circulating the atmosphere was installed. The ethylene concentration inside was adjusted to 100 ppm. After installing the sample catalyst, ethylene decomposition evaluation test 1
In order to check the ethylene adsorption performance of the sample catalyst in the same manner as above, the change in ethylene concentration was measured without first turning on the lamp by circulating the atmosphere with a fan for the first ten minutes.
It was found that the ethylene concentration did not change and ethylene was not adsorbed on the sample catalyst. After 10 minutes, the lamp was turned on, and 90 minutes after the lighting, the ethylene concentration was measured, and the results are shown in Table 3.

[Table 3] Type of catalyst Supported amount Remaining 90 mg after irradiation (mg / cm ² ) Ethylene concentration (ppm) X 1.6 18 Y 2.8 16 Z 3.7 14 Clearly from Table 3, Example 2 It is proved that the ethylene photocatalyst lamp with a reflection plate of 1) has an extremely excellent ethylene decomposing ability as compared with the tubular sheet catalyst of Comparative Example 1, and it can be seen that an excellent ethylene decomposing ability can be achieved with a small amount of catalyst.

[0012]

[Effect] Rather than irradiating light on only one side of the catalyst layer as in Comparative Example 1 and Example 1 by applying light energy from both sides of the photocatalyst layer as in the ethylene decomposition photocatalytic lamp with a reflector in Example 2. The ethylene resolving power can be remarkably improved. Therefore, the catalyst of the present invention is very effective in removing ethylene generated from fruits and vegetables and extending the freshness retention period of fruits and vegetables.

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Claims (6)

[Claims] 1. An ethylene decomposition photocatalytic lamp, wherein titanium oxide fine particles having a crystal particle size of 100 to 500 angstrom are supported on the surface of a light source lamp by using a binder having a good light transmission property. 2. The ethylene decomposition photocatalyst lamp according to claim 1, wherein the titanium oxide fine particles have a crystal particle size of 150 to 300 angstroms. 3. The ethylene decomposition photocatalyst lamp according to claim 1, wherein the binder is a silica-based binder. 4. The binder is 10 to 3 by weight of the catalyst component.
The ethylene decomposition photocatalytic lamp according to claim 1, 2 or 3, wherein the amount is 0%. 5. The ethylene decomposition photocatalytic lamp according to claim 1, wherein the light source is an ultraviolet lamp having a band gap of 3.2 eV or more and emitting ultraviolet rays having a wavelength of 388 nm or less. 6. The ethylene decomposition photocatalyst lamp according to claim 1, a reflector surrounding the ethylene decomposition photocatalyst lamp at a distance, and a space between the ethylene decomposition photocatalyst lamp and the reflector. An ethylene decomposing apparatus comprising means for introducing an ethylene-containing gas.