JP3488496B2 - Poison-resistant deodorizing photocatalyst - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention withstands a high humidity environment for adsorbing, decomposing and removing a foul-smelling substance generated in a refrigerator or a toilet or a foul-smelling substance generated during water treatment, and is a catalyst poison for sulfur compounds and the like. The present invention relates to a water-resistant deodorizing photocatalyst having a high deodorizing treatment ability in which the catalytic activity is less likely to decrease, and a method for regenerating a poisoning-resistant deodorizing photocatalyst after being used for deodorizing treatment.

[0002]

2. Description of the Related Art We are placed in an environment where various malodorous substances are generated in our daily lives. For example, various foul-smelling substances are generated from refrigerators, toilets, general household disposers, factory wastewater treatment facilities, and the like. Such malodorous substances include ammonia, amines, indoles, and scats.
Such as nitrogen compounds, alcohols, aldehydes, organic acids such as acetic acid, hydrogen sulfide, mercaptan,
Various substances such as sulfur compounds such as dimethyl sulfide can be mentioned. Among them, sulfur compounds generate sulfur dioxide, sulfur trioxide and sulfur oxides produced as a by-product from them during deodorization treatment, and these sulfur oxides adhere to the catalyst to reduce the deodorizing ability of the catalyst.

Many methods for removing these malodorous substances have been known in the past, but basically, the malodorous substances are adsorbed and removed or oxidatively decomposed. A technique for efficiently deodorizing a malodorous substance by adsorbing and removing the substance, periodically or artificially desorbing the adsorbed malodorous substance, and oxidizing and decomposing the desorbed malodorous substance has also been developed.

As a deodorant for removing such a malodorous substance, an adsorbent composed of activated carbon, zeolite, silica gel, alumina, etc. has been known as a typical one, but since it is easily absorbed by moisture, its deodorizing ability is lowered. Tend to do. However, the environment in which deodorization is performed has high humidity, so
There is a demand for a deodorant that is not affected by the water content of the processing gas.

[0005] Further, oxidative decomposition treatment of malodorous substances by heating is also widely carried out, and the technique of further efficiently deodorizing treatment by further lowering the treatment temperature by using a catalyst is widespread. In order to process a large amount of processing gas in which a malodorous substance is diluted in an apparatus, even if a catalyst is used, it requires a large amount of cost for heating to a temperature required for a catalytic reaction.

In order to reduce the operating cost, there has been proposed a deodorizing method using a photocatalyst capable of decomposing a malodorous substance only by exciting the photocatalyst such as titanium dioxide by irradiating with ultraviolet rays. Furthermore, by combining these, during normal operation, an energy-saving deodorizing technology has been developed that adsorbs and removes malodorous substances and regularly or irregularly irradiates light to more efficiently deodorize the adsorbed malodorous substances using a photocatalyst. ing. For example, various means described below have been proposed.

Japanese Unexamined Patent Publication (Kokai) No. 62-252875 discloses that a deodorizing device comprising a combination of an ultraviolet lamp and a photocatalytic semiconductor is installed in a refrigerator to exert deodorizing and sterilizing effects for a long period of time. However, there is no specific description about the structure and material of the photocatalytic semiconductor.

JP-A-1-189321 discloses a photocatalyst layer that is excited by light and is formed on the surface of an adsorbent that adsorbs odorous components, a photocatalyst kneaded into the adsorbent, or a photocatalyst that can be an adsorbent. And a light source for exciting the photocatalyst, the deodorizing device for a refrigerator is described. Further, the publication discloses that the shape of the adsorbent having a photocatalyst is honeycomb, sponge, mesh, fiber, plate,
It teaches that there are particles, that titanium dioxide is used as a photocatalyst, that an ultraviolet lamp is used as a light source for excitation, and that such a deodorizing device retains the deodorizing effect for a long period of time.

Japanese Unexamined Patent Publication (Kokai) No. 1-189322 discloses a member in which a photocatalyst is added to the surface of an adsorbent that adsorbs an odor component, or a photocatalyst is kneaded into the adsorbent, and an excitation source for exciting the photocatalyst. Deodorizing device is disclosed,
It is described that the odorous components can be collected in the adsorbent to efficiently deodorize and that the adsorbent has a large regeneration effect. Further, the publication teaches that the shape of the adsorbent is honeycomb, the materials are zeolite, activated carbon, porous ceramics and silica gel, and the materials for the photocatalyst are titanium dioxide, tungsten trioxide, and zinc oxide.

Japanese Unexamined Patent Publication No. 1-218635 discloses a deodorizing agent containing an adsorbent used in a refrigeration cycle and a photocatalyst (in some cases, IIA, IIIA, IVA, VA).
-Containing at least one element of group VIII, IB, IIB, IIIB, and IVB), and examples of adsorbents include activated carbon, alumina, silica, and examples of photocatalysts are titanium dioxide and stannic oxide. , Zinc oxide is shown. The publication describes that by using such a catalyst, the deodorizing effect is maintained for a long period of time and the deodorizing efficiency is improved.

Japanese Unexamined Patent Publication (Kokai) No. 2-164420 discloses a deodorizing device having a photocatalyst layer on the surface of an adsorbent, a deodorizing device for a refrigerator having an ultraviolet lamp for exciting a photocatalyst, and the structure and deodorizing agent of the refrigerator. No specific disclosure of the material is made.

[0012]

As described above, various deodorizing photocatalysts have been proposed before the present application, and a deodorizing photocatalyst in which a photocatalyst such as titanium dioxide is carried on a carrier capable of adsorbing and storing malodorous substances such as zeolite. A deodorizing treatment technique using is also known before the present application.

However, no photocatalyst capable of withstanding a harsh operating environment in which the humidity is high and a catalyst poison is present has been developed, and a photocatalyst having a high deodorizing ability to withstand these adverse conditions has been desired.

That is, when the deodorizing component in the treated gas consists only of nitrogen compounds, alcohols, aldehydes and organic acids and does not contain sulfur compounds, even if deodorizing is performed using a conventional photocatalyst. Although the activity deterioration of the photocatalyst is small, when the processing gas contains a malodorous substance composed of a sulfur compound such as hydrogen sulfide, methyl mercaptan, dimethyl sulfide, and dimethyl disulfide, sulfur dioxide and sulfur trioxide are generated by the deodorizing treatment, and Since the sulfur oxide is chemically and physically adsorbed on the photocatalyst, the deodorizing ability of the photocatalyst is reduced. Further, when a substance having no adsorptivity such as quartz or metal is used as the carrier, no deterioration of performance of the titanium dioxide photocatalyst is observed in deodorizing treatment of nitrogen compounds, alcohols, aldehydes and organic acids. However, when the treated gas contains a sulfur compound, sulfur dioxide or sulfur trioxide generated by the deodorizing treatment adheres to the catalyst layer and abruptly deteriorates the activity of the photocatalyst. A large amount of active component (titanium dioxide) is required to reduce even a slight decrease in activity due to poisoning of the photocatalyst. Therefore, a large amount of titanium dioxide is required to be supported on the carrier, but a large amount of titanium dioxide is easily peeled off on the carrier, which is a drawback.

Further, conventionally used zeolite is
Although it is effective in preventing this catalyst poisoning, it has a drawback that it is greatly affected by the water content in the processing gas.

[0016]

[Means for Solving the Problems] The inventors of the present invention are keen to develop a water-resistant deodorizing photocatalyst capable of withstanding a high humidity environment and having a high deodorizing treatment ability in which the catalytic activity is less likely to be deteriorated by a catalyst poison such as a sulfur compound. As a result of repeated research, zeolite having a silica / alumina ratio of at least 100 or more has excellent water resistance, and the catalyst poison is preferentially adsorbed and removed to prevent adhesion to the photocatalyst and deodorizing ability for a long time. I found that I could maintain. However, even a catalyst in which a commercially available zeolite with a high silica / alumina ratio is coated on a carrier to form an adsorption layer on which a photocatalyst excited by light is carried, adsorbs and stores deodorant components. However, if you try to oxidize and decompose the deodorizing components desorbed from the adsorption layer by turning on the photocatalyst excitation light source (ultraviolet lamp),
The oxidative degradation was significantly lower than that of the catalyst in which the photocatalyst was directly supported on the carrier. As a result of extensive studies to further improve the deodorizing ability, when titanium dioxide that constitutes the photocatalyst is supported on the adsorption layer, if the zeolite that constitutes the adsorption layer contains an alkali component, the alkali component is removed from the adsorption layer during the catalyst production process. It was found that the melted titanium dioxide is exposed on the surface and the catalytic activity is significantly reduced. That is,
It was found that by removing the alkali metal from the zeolite, the titanium dioxide worked effectively and the deodorizing ability was dramatically improved, and the content of the alkali metal formed on the carrier was 0.5% by weight as its oxide. %, The sulfur dioxide and sulfur trioxide are selectively adsorbed and occluded in the adsorption layer by producing a catalyst composed of an adsorption layer made of zeolite whose content is not more than 10% and a photocatalyst layer which is further excited by light and excited by light. It was found that epoch-making poisoning resistance can be imparted and the supported photocatalyst can be effectively actuated to reduce the supported amount of the photocatalyst. In addition, the photocatalyst thus produced is used at a temperature of 200 ° C., preferably 35 ° C., after being used for the adsorption decomposition treatment of a malodorous substance.
It was also found that the deodorizing ability can be regenerated by heating at a temperature of 0 ° C or higher.

The present invention has been made on the basis of these findings. A carrier, an adsorption layer made of zeolite having an alkali metal content formed thereon of 0.5% by weight or less as an oxide, and Further, the present invention provides a poisoning-deodorizing photocatalyst comprising a photocatalyst layer carried on the photocatalyst and excited by light.

The present invention also provides a carrier, a zeolite layer having an alkali metal content of 0.5% by weight or less as an oxide formed on the carrier, and further excited by light carried thereon. A method for regenerating a poisoning-resistant deodorizing photocatalyst, comprising using the poisoning-deodorizing photocatalyst comprising a photocatalyst layer for deodorizing a malodorous substance, and then calcining the catalyst at a temperature of 200 ° C. or higher.

The carrier material for the poisoning-deodorizing photocatalyst according to the present invention is not particularly limited, but a porous carrier is usually used and is a white carrier through which reaction gas and light can flow and which reflects light well. Preferably there is. The black carrier is not preferable because the light energy cannot be efficiently used. For example,
Inorganic white carriers such as cordierite, alumina, silica alumina, titania silica, zeolites, sepiolite, zeolite-sepiolite mixtures and the like are suitable. The carrier may have a honeycomb shape, a sponge shape, a mat shape, a woven cloth shape, a plate shape, a cylindrical shape, a granular shape, or the like, but particularly a honeycomb structure or a three-dimensional mesh shape in which reaction gas and light can easily flow. Structures are preferred. The cell shape of the honeycomb is arbitrary and may be polygonal such as triangular, quadrangular, pentagonal, hexagonal, or corrugated.
For example, as disclosed in Japanese Patent Publication No. 59-15028, an aggregate of ceramic fibers (hanicle carrier), that is, silica fibers, alumina fibers, aluminosilicate fibers, zirconia fibers, etc., which are bonded to each other by silica gel, A honeycomb structure formed by stacking a sheet-shaped aggregate of ceramic fibers selected from inorganic fibers in a honeycomb shape is particularly preferable because it has a small pressure loss and a large geometric surface area.

Another component of the poisoning-deodorant photocatalyst of the present invention is zeolite having excellent hydrophobicity (water resistance) which constitutes an adsorption layer for malodorous substances and catalyst poisons. Zeolites which can be used in the present invention include natural zeolites such as chabazite, mordenite, erionite, faujasite and clinopterolite and synthetic zeolites such as zeolite A, zeolite X, zeolite Y, zeolite L and ZSM-5. The ratio of alumina is increased.

Preferred zeolites in the present invention are modified crystalline aluminosilicates having a silica / alumina ratio of at least 100 or more, and crystalline silica containing almost no alumina, that is, silicalite, with silicalite being most preferred. Since silicalite contains almost no alumina, it has a very small ion exchange capacity, is hydrophobic, and has high water resistance. A typical silicalite has the following composition formula: R ₂ O: 0 to 1.5 M ₂ O: <0.05 Al ₂ O ₃ : 40 to
70SiO ₂ (In the formula, R represents a tetraethylammonium ion,
M represents an alkali metal cation. ).
As described above, silicalite does not contain alumina, but actually alumina as an impurity contained in the raw material at the time of production may remain in silicalite which is the final product. Does not affect the properties of silicalite. Preferred silicalites that can be used in the present invention have a silica / alumina ratio of 1
00 or more, preferably 250 or more, more preferably at least 400 or more. For details on the method for producing silicalite and its properties, see JP-A-54-7279.
No. 5, Japanese Patent Publication No. 56-40084, and 19
Nature published in 1978, Volume 271, Volume 5645
, Silicalite, a novel hydrophobic crystalline silica molecular sieve, on pages 512-516.

Further, the zeolite preferable in the present invention has a content of an alkali metal which affects the catalytic activity of titanium dioxide constituting the photocatalyst as an oxide thereof.
It is a zeolite reduced to 5% by weight or less, and more preferably 0.3% or less. That is, an important feature of the deodorizing photocatalyst of the present invention is that the content of an alkali metal such as potassium or sodium contained in zeolite is 0.5% by weight or less as its oxide.

The carrier itself may be composed of zeolite used in the adsorption layer.

[0024] Still another component of the poisoning-deodorizing photocatalyst of the present invention is a photocatalyst layer excited by light. Examples of the material of the photocatalyst layer include titanium dioxide (TiO ₂ ), tungsten trioxide (WO ₃ ), zinc oxide (ZnO) and the like, but titanium dioxide is particularly preferable. The crystal grain size of the oxide used as the photocatalyst layer is 100.
~ 500 Å, preferably 150-300
The one with angstrom has excellent resolution of malodorous substances by light. The amount of the catalyst component supported is 10 to 200 g / l, preferably 50 to 150 g / l, based on the total volume of the catalyst structure, together with the binder, and 20 to 200 g / l, preferably when the carrier is a honeycomb structure. Is 50 ~
150 g / l, 10 to 100 g / l, preferably 20 to 10 when the carrier is an aggregate of ceramic fibers
50 g / l, 2 to 50 g / l, preferably 2 to 15 g / l for those composed of a three-dimensional network structure are held on the carrier by the binder. The binder is a silica-based binder having a good light transmittance of 10 to 10% by weight of the catalyst component.
It is preferably used in an amount of 30%, but it can be retained on the carrier without it.

The light source may be any one capable of photochemically exciting a photocatalyst such as titanium dioxide,
Has a band cap of 3.2 eV or more and a wavelength of 388
Any ultraviolet lamp that emits ultraviolet rays of nm or less and supplies light energy to the catalyst component may be used.

Even if the poisoning-resistant deodorizing catalyst of the present invention is subjected to repeated deodorizing treatment, the catalytic activity is deteriorated due to the adhesion of catalyst poisons, mist, by-products, etc. By calcining the catalyst with reduced catalytic activity at a temperature of 200 ° C. or higher, preferably 350 ° C. or higher, the reduced catalytic activity can be recovered to almost the same level as that of the new catalyst, and the deteriorated catalyst It was found that the reproduction processing of was possible.

[0027]

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.

1. Preparation of slurry solution for forming adsorption layer (1) Slurry solution A 2.5 kg of 20 wt% Snowtex OUP (manufactured by Nissan Chemical Industries, Ltd.) (containing 20 wt% as SiO ₂ )
A binder solution was prepared by adding 5 kg of ion-exchanged water, and PURASIV manufactured by UOP was added to the binder solution.
-420 (containing 0.9% by weight of K ₂ O) was washed and charged with 5.0 Kg of depotassium silicalite having a K ₂ O content of 0.01% by weight while stirring with a propeller stirrer. And a solid content of 27.5 wt% slurry solution A (S
iO _2: 2.5 wt%, de potassium silicalite: 25
20% by weight, silica / alumina ratio: 250) was prepared.

(2) Slurry solution B U as silicalite which has not been subjected to washing and removal treatment of potassium
A slurry solution B was prepared in the same manner as in (1) except that PURAS IV-420 (containing 0.9% by weight of K ₂ O) manufactured by OP was used.

(3) Slurry Solution C Silicalite was replaced with 13X type zeolite (PURASIVE-628 manufactured by UOP) having a high sodium content of 6% by weight and a low silica / alumina ratio of 2. , (1) and a slurry solution C was prepared.

2. Preparation of catalyst layer forming slurry solution 60 wt% concentrated nitric acid 60 g in ion-exchanged water 30.0 Kg
5.0 kg of Snowtex OUP manufactured by Nissan Chemical Industries, Ltd. as a binder ( ₂ as SiO 2
0% by weight) was added and mixed. 5.0K to this solution
The g of Nippon Aerosil Co., Ltd. titanium dioxide powder P-25 into the compression while mixing with a propeller stirrer, a SiO ₂ 2.5 wt%, the catalyst layer forming slurry solution 40Kg containing TiO ₂ 12.5% by weight Created.

3. Preparation of catalyst Example 1 Hanicle carrier (200 cells, size 60 mmX150 mmX10 m, manufactured by Nichias Co., Ltd.) which is an assembly of ceramic fibers.
m) is immersed in the above-mentioned adsorption layer forming slurry solution A and taken out, and excess slurry is removed by blowing air,
It was dried at a temperature of 150 ° C. for 2 hours. 38 dry catalyst
The mixture was calcined at 0 ° C. for an additional hour, and an adsorption layer consisting of 80 g of depotassium silicalite per liter of catalyst was coated.
A coated carrier A was prepared.

The carrier A on which the adsorption layer made of depotassium silicalite was formed was dipped in the catalyst layer forming slurry, taken out, and excess slurry was blown off to remove it, and then dried at a temperature of 150 ° C. for 2 hours. . The dried catalyst was further calcined at a temperature of 380 ° C. for 1 hour, and 30 g of TiO ₂ (liter per 1 liter of catalyst) (2.0 per unit area (cm ² )).
Catalyst A having an adsorption layer composed of depotassium silicalite carrying (corresponding to mg) was prepared.

Comparative Example 1 The same nicicle carrier (2) manufactured by Nichias Co. as used in Example 1 was used.
00 cell, size 60mmX150mmX10mm),
After immersing in the above-mentioned catalyst layer forming slurry solution and taking it out, the excess slurry is blown off with air to remove it, and then at 150 ° C.
It was dried at the temperature of 2 hours. 380 additional dried catalyst
Calcination at ℃ for 1 hour, 35gT per liter of catalyst
A catalyst W having no adsorption layer supporting iO ₂ (corresponding to 2.3 mg per unit area (cm ² )) was prepared.

Comparative Example 2 The same nicicle carrier (2) manufactured by Nichias Co. as used in Example 1 was used.
00 cell, size 60mmX150mmX10mm),
82 g per 1 liter of catalyst in the same manner as in Example 1 except that the above-mentioned slurry solution B for forming an adsorption layer was immersed and taken out.
Carrier B was prepared by coating an adsorption layer made of silicalite on which potassium was not removed by washing.

This carrier B was treated in the same manner as in Example 1 to carry 32 g of TiO ₂ per liter of catalyst (corresponding to 2.1 mg per unit area (cm ² )) without silica treatment. A catalyst X having an adsorption layer of light was prepared.

Comparative Example 3 The same honey carrier (2) manufactured by Nichias Co. as used in Example 1 was used.
00 cell, size 60mmX150mmX10mm),
82 g per 1 liter of catalyst in the same manner as in Example 1 except that the slurry solution C for forming an adsorption layer was immersed and taken out.
Carrier C was prepared by coating an adsorption layer of zeolite X13 on which the potassium in Example 3 was not removed by washing.

This carrier C was treated in the same manner as in Example 1 below, and 31 g of TiO ₂ per 1 liter of catalyst (corresponding to 2.1 mg per unit area (cm ² )) was carried out without potassium removal treatment. A catalyst Y having an adsorption layer of X13 was prepared.

Comparative Example 4 The above catalyst layer-forming slurry was uniformly applied to an aluminum plate (235 mm × 150 mm) by an air spray method and then dried at a temperature of 150 ° C. for 2 hours. The dried catalyst was further calcined at a temperature of 380 ° C. for 1 hour, and the catalyst supporting 2.1 mg per 1 cm ² was molded into a 75 mm cylindrical shape to prepare a catalyst Z.

4. Performance evaluation (1) Acetaldehyde adsorption decomposition performance evaluation test 12W tube output Prince UV ultraviolet sterilization lamp (QGULR-11-20) that emits ultraviolet light having a wavelength of 254 nm.
0N), a reflector such as an aluminum plate is installed behind it in order to increase the irradiation efficiency of the lamp, and the sample catalyst is placed at a position 4 cm away from the lamp, and the sample catalyst is placed below it. 20 μl of acetaldehyde solution was injected into a 16-liter glass case equipped with a fan for circulating the air, and the acetaldehyde concentration in the glass case was adjusted to 500.
It was adjusted to ppm. Similar performance tests were carried out on the sample catalyst in a dried state and the sample catalyst in a desiccator filled with water for 1 day to sufficiently absorb moisture. First,
In order to check the adsorption performance of acetaldehyde, the air was circulated by a fan for the first 30 minutes, and the lamp was not turned on.
It was confirmed that the adsorption equilibrium was completely reached at 0 minutes and no further adsorption occurred.

After 30 minutes, the lamp was turned on and the change with time of the concentration of acetaldehyde after lighting was measured.
The results are shown in Table-1.

This test was repeated several times, but the treatment time required to completely decompose the aldehyde with the photocatalyst by turning on the lamp was almost constant, and no decrease in catalytic activity was observed.

[0043]                                  Table-1                         Adsorption (30 minutes) UV irradiation (30 minutes later) UV irradiation (60 minutes later)        Blank 501 491 485        Catalyst A Dry product 26 4.3 *               Hygroscopic product 37 6.0 *        Catalyst W Dry product 256 4.1 *               Hygroscopic product 415 9.9 *        Catalyst X Dry product 25 15.9 4.5               Hygroscopic product 36 16.7 4.8        Catalyst Y Dry product 26 18.4 5.5               Hygroscopic product 395 37.5 9.3 Note: * indicates that measurement is not possible.

As is clear from Table 1, the catalyst W having no adsorption layer has inferior acetaldehyde adsorption performance as compared with the catalyst A, the catalyst X and the catalyst Y having the adsorption layer,
Especially when the catalyst absorbs moisture, the adsorption performance is extremely poor. Also,
The catalyst Y having an adsorption layer is also a catalyst A and a catalyst X in a dry product.
Although the adsorbing performance of acetaldehyde is almost the same as the above, it can be seen that the adsorbing performance is drastically deteriorated in the case of absorbing hygroscopicity. That is, it was proved that the adsorption performance of zeolite having a low silica / alumina ratio was drastically lowered by moisture absorption, whereas the adsorption performance of silicalite having a high silica / alumina ratio was hardly changed even when moisture was absorbed. .

In addition, the catalyst A of the present invention is remarkably improved in adsorption performance as compared with the catalyst W having no adsorption layer, and the adsorption performance hardly changes even when the catalyst absorbs moisture. -1
It is clear that the catalyst X having an adsorption layer made of silicalite not subjected to dealkalization has almost the same acetaldehyde adsorption performance as the catalyst A of the present invention having an adsorption layer made of potassium-depleted silicalite. But not
It was proved that the resolution of acetaldehyde was much worse even though the loading of photocatalyst was almost the same. That is, this clearly shows that the alkali metal component in the zeolite affects the catalytic activity.

That is, the catalyst A of the present invention having an adsorption layer composed of silicalite having a high content of silica / alumina having a low content of alkali metal components, whether it is a dried product or a hygroscopic product, has excellent adsorption performance and catalytic activity. It is clearly proved from Table 1 that both are excellent.

(2) Dimethyl sulfide adsorption decomposition performance evaluation test 12 W tube output UV germicidal lamp (QGULR-11-20, which emits ultraviolet rays having a wavelength of 254 nm)
0N), in order to increase the irradiation efficiency of the lamp, a reflector such as an aluminum plate is installed behind it, and the sample catalyst is placed at a position 4 cm away from the lamp. A lamp was set at the center of the catalyst, and 25 μl of the dimethyl sulfide solution was injected into a 16-liter glass case in which a fan for circulation of the atmosphere was installed in the lower part of the catalyst to adjust the dimethyl sulfide concentration in the glass case to 500 ppm. A sample catalyst in a dry state,
The same performance test was carried out on the sample catalysts in a desiccator filled with water for 1 day to sufficiently absorb moisture.
First, in order to check the adsorption performance of dimethyl sulfide, the adsorption of dimethyl sulfide was measured without illuminating the lamp by circulating the atmosphere with a fan for the first 30 minutes, and the adsorption equilibrium was completely reached in 30 minutes. It was confirmed that the above adsorption did not occur.

After the lapse of 30 minutes, the lamp was turned on, and the change with time of the concentration of dimethyldisulfide after the lighting was measured. After the lamp was turned on to completely decompose dimethyldisulfide with a photocatalyst, this evaluation test was repeated several times for each sample catalyst, and the change with time of the concentration of dimethyldisulfide was similarly measured. The results are shown in Table-2.

[0049]                                  Table-2                   Adsorption (30 minutes) UV irradiation (after 30 minutes) (after 60 minutes) (after 90 minutes) Blank 427 406 400 400 398 Catalyst A Dry product 1 time 10 5 0.1 *               2 times 11 8 3.0 0.3               3 times 12 10 4.8 1.2               4 times 13 12 7.0 7.0 2.4        Hygroscopic product 1 time 14 6 0.3 * Catalyst W Dry product 1 time 331 112 3 *               2 times 350 204 88 8               3 times 356 255 149 58               4 times 337 232 127 127        Hygroscopic product 1 time 402 150 10 1.0 Catalyst X Dried product 1 time 10 7 5.1 2.3               2 times 11 9 6.5 3.0               3 times 12 14 8.2 4.5               4 times 13 16 11.2 6.5        Hygroscopic product 1 time 14 9 6.2 3.1 Catalyst Y dried product 1 time 101 7 5.3 2.6        Hygroscopic product 2 times 380 93 23.7 4.2 Catalyst Z Dry product 1 time 422 54 3.0 *               2 times 433 330 252 220 Note: * indicates that measurement is not possible.

As is clear from Table 2, the catalyst W having no adsorption layer is inferior to the catalyst A, the catalyst X and the catalyst Y having the adsorption layer in the adsorption performance of dimethyldisulfide, and particularly the catalyst When it absorbs moisture, the adsorption performance is significantly reduced. Further, the catalyst Y having an adsorption layer also shows a certain degree of adsorption performance of dimethyldisulfide, although it is inferior to the catalyst A and the catalyst X in the dry product, but the one that is made to absorb moisture is
It can be seen that the adsorption performance deteriorates sharply. That is, for a sulfur compound such as dimethyldisulfide, the adsorption performance of a zeolite having a small silica / alumina ratio sharply decreases due to moisture absorption, whereas silicalite having a high silica / alumina ratio absorbs even if moisture absorption occurs. It was proved that the performance was almost unchanged.

Further, from Table 2 as well, it is recognized that by repeating the evaluation test, sulfur dioxide or sulfur trioxide is produced as a reaction product and affects the photocatalyst. Particularly, in the catalyst W and the catalyst Z having no adsorption layer, the catalytic activity is remarkably reduced due to the poisoning of the catalyst. The catalyst Z in which the photocatalyst is supported on the aluminum plate has no adsorption performance at all, and although the initial photoreaction performance of the first time is about the catalyst W, the photoreaction performance of the second repetition is remarkably reduced, and the catalyst due to catalyst poisoning It was proved that the activity was severely reduced.

Further, the catalyst A of the present invention in which the adsorption layer made of potassium-depleted silicalite is formed is made of the catalyst X in which the adsorption layer made of silicalite which has not been dealkalized is formed and the zeolite containing a large amount of sodium. It also has much better catalytic activity for dimethyldisulfide than catalyst Y with an adsorbed layer formed, and is less likely to be poisoned by sulfur dioxide or sulfur trioxide, resulting in little decrease in catalytic activity even after repeated evaluation tests. It was proved.

(3) Methyl mercaptan adsorption decomposition performance evaluation test In the dimethyl sulfide adsorption decomposition performance evaluation test,
In place of dimethyl sulfide, 8.0 ml of 100% methyl mercaptan gas was injected and the concentration of methyl mercaptan in the glass case was adjusted to 500 ppm. -3. Methyl mercaptan does not turn on the lamp, but only by circulation by the fan 3
It was confirmed that the adsorption equilibrium was completely reached at 0 minutes.

[0054]                                  Table-3                   Adsorption (30 minutes) UV irradiation (after 30 minutes) (after 60 minutes) (after 90 minutes) Blank 480 462 450 450 Catalyst A Dry product 1 time 102 85 0.5 *               2 times 112 80 0.1 *               3 times 110 75 * *               4 times 115 70 * *               7 times 118 92 4.3 4.3 0.2        Hygroscopic product 1 time 120 95 1.0 * Catalyst W Dry product 1 time 450 130 4 *               2 times 451 120 2 *               3 times 454 112 1.4 *               4 times 458 100 1.0 *               7 times 463 160 10.2 1.5        Hygroscopic product 1 time 462 170 12 1.2 Catalyst X Dried product 1 time 105 95 39 8               2 times 100 92 36 4               3 times 105 90 30 2.3               4 times 110 88 26 0.9               7 times 113 103 45 13        Hygroscopic product 1 time 124 105 45 11 Catalyst Y Dry product 1 time 110 102 45 10        Hygroscopic product 1 time 420 250 85 23 Note: * indicates that measurement is not possible.

It is clear from Table 3 that the catalyst A of the present invention is excellent in both adsorption performance and catalytic activity of methyl mercaptan regardless of whether it is a dried product or a hygroscopic product.

That is, the catalyst A of the present invention having an adsorption layer composed of silicalite having a high content of silica / alumina having a low content of alkali metal components has the same adsorption performance and catalytic performance regardless of whether it is a dried product or a hygroscopic product. It has been proved that the catalyst activity is excellent, and the catalyst activity is not significantly deteriorated even by the catalyst poisoning by the sulfur oxide generated by the deodorizing treatment of the treated gas containing the malodorous substance including the sulfur compound.

Further, from Table 3, it can be seen that the decomposition performance of methyl mercaptan is repeatedly improved by repeating the evaluation test, but the decomposition performance gradually improves up to the fourth time although there is a performance order depending on the sample catalyst. This is because the generated sulfur dioxide is oxidized to sulfur trioxide and converted to sulfuric acid by the water content in the air, which accelerates the decomposition rate of methyl mercaptan by acid beyond the poisoning deterioration rate of the catalytic activity of the sample catalyst. However, the decomposition performance deteriorates at the 7th time. This indicates that the poisoning deterioration rate of the catalytic activity of the sample catalyst is higher than the decomposition rate of methyl mercaptan by the acid.

In order to confirm that the catalytic activity of the sample catalyst is actually improved, but the catalytic activity is actually reduced, the above-mentioned acetaldehyde adsorption decomposition was conducted on the sample catalyst which was repeatedly evaluated four times. A performance evaluation test was conducted to try to evaluate the acetaldehyde adsorption decomposition performance. The results are shown in Table-4.

[0059]                                  Table-4                    Adsorption UV irradiation                   (30 minutes) (30 minutes later) (60 minutes later) (90 minutes later) (120 minutes later) Blank 501 491 485 480 476 Catalyst A New catalyst 26 4.3 *    4 times use product 28 10 3.2 * * Catalyst W New catalyst 256 4.1 *    4 times use product 306 80 13 4.5 1.0 Catalyst X New catalyst 25 15 4.5    Used 4 times 27 20 14 7.0 1.5 Note: * indicates that measurement is not possible.

As is clear from Table 4, the sample catalysts subjected to the methylmercaptan adsorptive decomposition performance evaluation test four times repeatedly have deteriorated catalytic activity as compared with the new catalysts, but the catalyst A of the present invention is It was proved that even if compared with the catalyst W and the catalyst X, the catalyst was less deteriorated and had excellent poisoning resistance.

5. Method for Regenerating Used Catalyst Example 2 Catalyst A, Catalyst W, and Catalyst X, which had been subjected to the evaluation test four times in the dimethylsulfide adsorption decomposition performance evaluation test and had reduced catalytic activity, were calcined at a temperature of 350 ° C. for 1 hour. .

For each catalyst regenerated by calcination,
The above-mentioned dimethyl sulfide adsorption decomposition performance evaluation test and methyl mercaptan adsorption decomposition performance evaluation test were conducted.
The results are shown in Table 5 for dimethyl sulfide,
Table 6 shows methyl mercaptan.

[0063]                                    Table-5                   Adsorption (30 minutes) UV irradiation (after 30 minutes) (after 60 minutes) (after 90 minutes) Blank 427 406 400 400 398 Catalyst A Dry product 1 time 10 5 0.1 *               4 times 13 12 7.0 7.0 2.4     350 ° C re-baking 10 5 0.1 * Catalyst W Dry product 1 time 331 112 3 *               4 times 337 232 127 127     350 ° C re-baking 306 762 * Catalyst X Dried product 1 time 10 7 5.1 2.3               4 times 13 16 11.2 6.5     350 degreeC re-baking 10 7.1 5.0 2.2 Note: * indicates that measurement is not possible.

[0064]                                   Table-6                   Adsorption (30 minutes) UV irradiation (after 30 minutes) (after 60 minutes) (after 90 minutes) Blank 480 462 450 450 Catalyst A Dry product 1 time 102 85 0.5 *               4 times 115 70 * *     350 ° C re-baking 105 86 0.5 Catalyst W Dry product 1 time 450 130 4 *               4 times 458 100 1.0 *     350 degreeC re-baking 450 132 4.1 Catalyst X Dried product 1 time 105 95 39 8               4 times 110 88 26 0.9     350 ° C re-baking 106 94 40 8 Note: * indicates that measurement is not possible.

As is clear from Tables 5 and 6, it can be seen that the catalyst whose catalytic activity has been lowered through repeated evaluation tests has recovered the catalytic activity to the same level as the new catalyst by the regeneration treatment. That is, it was proved that even if the catalyst used in the deodorization treatment had a lowered catalytic activity, the catalyst was regenerated by calcining.

As is clear from Table 3, in the evaluation test of methyl mercaptan, there is a tendency that the decomposition performance gradually improves as described above. As is clear from Table-6, although the catalyst subjected to the regeneration treatment recovers to the same level of catalytic activity as the new catalyst for methyl mercaptan, it seems to be inferior to the catalytic activity of the catalyst before regeneration. When the acetaldehyde adsorptive decomposition performance evaluation test was performed as described above, the catalytic activity of the catalyst subjected to the evaluation test four times was actually reduced. Therefore, an acetaldehyde adsorption / decomposition performance evaluation test was similarly performed on the regenerated catalyst, and the results are shown in Table 7.

[0067]                                    Table-7                    Adsorption UV irradiation                   (30 minutes) (30 minutes later) (60 minutes later) (90 minutes later) (120 minutes later) Blank 501 491 485 480 476 Catalyst A New catalyst 26 4.3 *    4 times use product 28 10 3.2 * * 350 ° C re-baking 27 4.5 Catalyst W New catalyst 256 4.1 *    4 times use product 306 80 13 4.5 1.0 350 ° C re-baking 260 4.0 * Catalyst X New catalyst 25 15 4.5    Used 4 times 27 20 14 7.0 1.5 350 ° C re-baking 25 16 4.4 Note: * indicates that measurement is not possible.

As is clear from Table 7, the catalytic activity of the sample catalyst subjected to the methylmercaptan adsorptive decomposition performance evaluation test four times was deteriorated as compared with the new catalyst, and the acetaldehyde adsorptive decomposition performance was improved by the regeneration treatment. You can see that it is recovering. That is, it was proved that the regeneration treatment restored the adsorptive decomposition performance of both methyl mercaptan and acetaldehyde, and that catalyst regeneration was possible.

[0069]

Industrial Applicability The poisoning-resistant deodorizing catalyst of the present invention is capable of adsorbing and removing a malodorous substance during normal operation and irradiating the adsorbed malodorous substance with light to decompose it at an extremely high level of operation. It is an energy-saving deodorizing photocatalyst that can reduce costs.

Since the poisoning-resistant deodorization catalyst of the present invention uses a zeolite having an alkali metal content of 0.5% by weight or less as its oxide, not only the activity as a catalyst is improved but also a sulfur compound is used. The resistance to poisoning is greatly increased compared to conventional catalysts.

Further, since a zeolite having a silica / alumina ratio of at least 100, preferably silicalite is used as the zeolite, it has high water resistance and is not affected by the moisture in the treated gas, and the deodorizing ability is lowered. do not do.

Further, the catalyst can be regenerated by firing it at a temperature of 200 ° C. or higher after the catalyst has been used for deodorizing a malodorous substance several times and the catalytic activity has decreased, and the catalyst can be regenerated to the same level as a new catalyst. It has a remarkably excellent effect that the activity is restored.

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Claims (10)

(57) [Claims] 1. A support, an adsorption layer made of zeolite having an alkali metal content of 0.5% by weight or less as an oxide formed on the support, and further excited by light carried thereon. A poison-deodorizing photocatalyst comprising a photocatalyst layer. 2. The poisoning-deodorizing photocatalyst according to claim 1, wherein the carrier has a honeycomb structure. 3. The poisoning-deodorizing photocatalyst according to claim 1, wherein the carrier has a honeycomb structure composed of a sheet-shaped aggregate of ceramic fibers. 4. The poisoning-deodorizing photocatalyst according to claim 1, wherein the alkali metal is potassium or sodium. 5. The zeolite is selected from the group consisting of zeolite A, zeolite X, zeolite Y, zeolite L, ZSM-5 and silicalite having a silica / alumina ratio of at least 100 or more. The poisoning-resistant deodorizing photocatalyst according to any one of 1 to 4. 6. The poisoning-deodorizing photocatalyst according to any one of claims 1 to 5, wherein the zeolite is silicalite having a silica / alumina ratio of at least 250 or more. 7. The poisoning-deodorizing photocatalyst according to claim 1, wherein the photocatalyst layer is made of titanium dioxide. 8. The poisoning-deodorizing photocatalyst according to claim 7, wherein the titanium dioxide has a crystal particle size of 100 to 500 angstrom. 9. The poisoning-deodorizing photocatalyst according to claim 8, wherein the titanium dioxide has a crystal particle size of 130 to 300 angstroms. 10. A carrier, an adsorption layer made of zeolite having an alkali metal content of 0.5% by weight or less as an oxide formed on the support, and further excited by light carried thereon. The method for regenerating a poisoning-resistant deodorizing photocatalyst, which comprises using the poisoning-deodorizing photocatalyst comprising a photocatalyst layer for deodorizing a malodorous substance, and then calcining the catalyst at a temperature of 200 ° C or higher.