JPH0924272A - Self-regeneration type adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To demonstrate the sufficient adsorption against a malodorous component by containing a platinum and/or palladium component and hydrophobic zeolite having specified values of silica/alumina molar ratio and the specific surface respectively and also recover the adsorption properties by heating the adsorbed malodorous component. SOLUTION: This self-regeneration type adsorbent is prepared by coating an electric heating medium with hydrophobic zeolite having the silica/alumina molar ratio of 70 or over and the specific surface of 500m<2> /g or more, on which a platinum and/or palladium component is carried, or a mixture of some other porous substance, on which a metal component of the above-said hydrophobic zeolite is carried, with hydrophotic zeolite. As the hydrophotic zeolite is contained in the adsorbent, high adsorption properties are demonstrated to a slight supply amount of ammonia or the like as a malodorous component even under the atmosphere containing the water content. A malodorous substance is removed by the catalyst action of a platinum and/or palladium component and the oxidization generated by the adsorption properties of a porous substance by heating every given hours.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an adsorbent having a self-regenerating function. More specifically, when the adsorbent adsorbs a malodor generated inside the refrigerator or the garbage disposal, it is heated to decompose and remove the malodorous substance adsorbed by the interaction between the adsorbent and the platinum group compound. It is a self-regenerating type adsorbent that has an excellent property of recovering the adsorptivity.

[0002]

2. Description of the Related Art Recently, as the living environment changes, interest in removing a small amount of odorous gases such as ammonia, mercaptans, amines, aldehydes, hydrogen sulfide, and lower carboxylic acids present in living spaces is increasing. A deodorant is required to remove these malodorous gases and maintain a comfortable living environment, and various malodorous gas adsorbents are also used in home life.

For example, as a method for removing various odors generated inside a refrigerator and odors generated when using a garbage processor, the following are practical methods.

First, there is a method of removing by utilizing an adsorbent such as activated carbon, and in principle utilizing a physical adsorption action. Activated carbon is a unique material that exhibits extremely excellent adsorbability as a non-polar adsorbent, and exhibits high adsorbability for almost all gaseous substances. However, it is difficult to sufficiently remove ammonia and lower aliphatic aldehydes in the above-mentioned malodor with only ordinary activated carbon. Further, when the saturated adsorption is reached, the life of the adsorbent is expired, and therefore it is necessary to replace it regularly.

As an adsorbent other than activated carbon, silica gel,
There are various types such as activated alumina, zeolite, activated clay and synthetic resin, but their adsorption capacity is less than that of activated carbon. Further, since the surface thereof is usually hydrophilic, moisture is preferentially adsorbed from the malodorous gas containing water, so that the malodorous gas may not be sufficiently removed.

When ozone is used, it is necessary to devise the device so that harmful ozone does not leak out of the system, and it is also necessary to install an ozone generating tube, which increases the cost of the device.
Further, since the volume of the device is large and very bulky, there is a drawback that the space cannot be effectively used.

On the other hand, there is known a method of completely regenerating the adsorbent by oxidatively decomposing the adsorbed malodorous substance at a high temperature with an adsorbent carrying a noble metal catalyst. The following are examples of using this method. First, JP-A-2-213080
The publication discloses a heating device using a catalyst coating layer composed of a platinum compound and activated alumina, but since the application is an electric stove, an electric kotatsu, etc. In many cases, the performance is not fully exhibited. This is because the physical adsorption action of solids generally decreases as the temperature rises.

Further, Japanese Patent Laid-Open No. 2-275277 discloses an example of a deodorizing device for a cooling storage in which a heater for defrosting is coated with a deodorizing body containing a platinum catalyst, and Japanese Utility Model Laid-Open No. 4683/1992 discloses an odor adsorbent and An example of a refrigerator with a deodorizer, which is coated with a deodorizing material mixed with an oxidation accelerator, is disclosed. However, these publications do not describe specific examples of removal tests using a malodorous gas.

In the case of the high temperature oxidative decomposition method, it is necessary to use a flame-retardant inorganic compound as an adsorbent, but as described above, the adsorption capacity of an inorganic adsorbent is generally smaller than that of activated carbon and the like. The malodorous gas cannot be sufficiently removed only by the system adsorbent.

[0010]

DISCLOSURE OF THE INVENTION The present invention is intended to remove a small amount of malodorous components present in daily living space, and has a sufficient adsorption action for these malodorous components and also the adsorbed malodorous components. It is intended to provide a self-regenerating type adsorbent having a function of recovering the adsorptivity by heating the components with a heater or the like.

[0011]

Means for Solving the Problems As a result of various researches by the present inventors for an adsorbent having high heat resistance and large adsorption capacity for malodorous components, it was found that hydrophobic zeolite is suitable for this purpose. . As its name implies, hydrophobic zeolite has a hydrophobic surface, so it is effective in removing malodorous gas in the presence of water, and in removing lower aliphatic aldehydes and ammonia, which cannot be sufficiently removed by ordinary zeolite. It was found to be very good. Further, based on this, the present invention has been achieved as a result of studying the composition and heating medium of the deodorant containing platinum and / or palladium compounds for oxidizing / decomposing the adsorbed malodorous component.

That is, a self-regenerating type adsorbent containing a compound of platinum and / or palladium and a hydrophobic zeolite having a silica / alumina molar ratio of 70 or more and a specific surface area of 500 m ² / g or more, Self-regenerative adsorption in which the hydrophobic zeolite carrying the metal compound or a mixture of the other porous material carrying the metal compound and the hydrophobic zeolite is applied to an electric heating medium to form an adsorbent layer on the surface thereof. It is an agent. Here, the silica / alumina molar ratio of the hydrophobic zeolite is preferably 200 or more, and the surface of the electric heating medium is preferably aluminum, stainless steel, heat-resistant glass or cordierite.

Hereinafter, the present invention will be described in detail.

The adsorbent of the present invention contains platinum and / or palladium compounds as main components, and silica / zeolite /
Alumina molar ratio is 70 or more and specific surface area is 500 m ² / g
It is necessary that the above-mentioned hydrophobic zeolite is contained. Here, the metal compound is used by being supported on a hydrophobic zeolite, or after being supported on a zeolite other than the above-mentioned hydrophobic zeolite or another porous substance, it is further mixed with a hydrophobic zeolite to form an adsorbent. Is more preferable.

The compound of platinum or palladium is not particularly limited and a wide range of compounds can be used.
Platinum compounds are preferably chloroplatinic acid and a platinum ammine complex, and palladium compounds are preferably palladium chloride and a palladium ammine complex. When these metal compounds are supported on hydrophobic zeolite or other porous substances, the oxidative / degradability of malodorous components is further enhanced by the synergistic action with the adsorptivity of these porous substances.

The amount of platinum and / or palladium compound supported on zeolite or the like is not particularly limited, but is preferably 0.
The content is 01 to 10.0% by weight, (converted to metallic platinum or palladium, the same applies hereinafter), and more preferably 0.1 to 5% by weight. If the supported amount is less than 0.01% by weight, the catalytic effect will be poor,
Considering that these metal compounds are extremely expensive, it is not possible to find an effect sufficient to use when the supported amount exceeds 10.0% by weight.

The hydrophobic zeolite or other porous substance carrying a platinum compound is supported at 200 ° C. to 500 ° C. after the metal compound is supported on the porous substance by a conventional method such as an ion exchange method or an impregnation method. It is prepared by firing in the temperature range of.

The adsorbent of the present invention contains, as an essential component, a hydrophobic zeolite having a silica / alumina molar ratio of zeolite of 70 or more and a specific surface area of 500 m ² / g or more. The above zeolite is also used as a carrier for platinum and / or palladium compounds, and can be used as a mixture with a hydrophobic zeolite that does not carry a metal compound.

Zeolite is a water-containing alkali metal salt or alkaline earth metal salt (Me ² / n) of crystalline aluminosilicate.
O ・ Al ₂ O ₃・ xSiO ₂・ yH ₂ O, where Me; Na, K, Ca, etc., n;
It is a porous substance having a three-dimensional skeleton and a pore structure formed in the gaps, with a valence of Me, x, y; integer). 300 m ² / g
It has the above specific surface area and high adsorptivity based on it.
Includes those with a fairly wide range of compositions, pore sizes, and pore volumes, including natural and synthetic products. Although the particle size and shape are not particularly limited, the pore volume is 0.3 ml / g or more and the particle size is 50 mesh under (particle size is about 0.3 mm or less) due to the relationship between the amount of platinum or palladium compound supported and the moldability.
Is preferred.

In the adsorbent of the present invention, the hydrophobic zeolite is used as a carrier for a platinum or palladium compound, and the hydrophobic zeolite not loaded with a metal compound is
It may be used as a mixture with zeolite other than the hydrophobic zeolite carrying these metal compounds. Hydrophobic zeolite is an ordinary zeolite that has been given a special chemical treatment to impart hydrophobicity to the surface to increase the amount of malodorous substances adsorbed, and to increase the silica content in the aluminosilicate composition of the zeolite. It is a high silica zeolite.

[0021] For example, ZSM series such as zeolite ZSM-5, silicalite, or super stable type obtained by dealumination treatment of existing Y-type zeolite by steam treatment or the like.
Y-type zeolite (US-Y) and the like are included. The silica / alumina molar ratio must be at least 70 or higher, preferably 200 or higher. Specifically, as described in JP-A No. 64-85113, the silica / alumina molar ratio is 200 to 500 and the pore size is
6.2 A or more of silicalite or dealuminated Y-type zeolite such as hydrophobic zeolite or Cosmet
Suitable are the hydrophobic molecular sheep type deodorizers "Absentu" and "Sumerlite" manufactured by UOP, Inc. of U.S.A. described in ics & Toiletries Vol. 109 (1994) P.77-82.

Other than the zeolite, any adsorbent of the present invention can be used as a carrier for platinum compounds and the like as long as it is a flame-retardant or non-combustible porous substance having a large specific surface area and a high adsorbability. These porous materials supporting a metal compound are used as a mixture with an unsupported hydrophobic zeolite. Examples of these porous substances include activated alumina and silica gel.

The activated alumina used in the present invention contains aluminum oxide as a main component and has a porous structure and exhibits high adsorption. The pore volume, particle size, and shape are not particularly limited, but due to the relationship between the amount of platinum or palladium compound supported and the molding processability, the pore volume is 0.3 ml / g or more and the particle size is
50 mesh under (particle diameter of about 0.3 mm or less) is preferable.

The silica gel used in the present invention is an adsorbent produced by solidifying a silicic acid colloidal solution. The main component is silicon dioxide, which has a pore structure, has a specific surface area of 90 to 500 m ² / g, and exhibits high adsorptivity. Its pore volume, particle size,
The shape is not particularly limited, but the pore volume is 0.3 ml due to the relationship between the amount of platinum or palladium compound supported and the moldability.
/ g or more, the particle size is 50 mesh under (particle size is about 0.3 m
m or less) is preferable.

As can be seen from the fact that these porous materials have an extremely large specific surface area, not only the surface that can be observed from the outside but also the inside of the material is filled with micropores or cracks, and the high adsorptivity based on the Van der Waals force. have. Among these porous materials other than the hydrophobic zeolite, zeolite is most preferable as a carrier because it has a relatively large specific surface area and therefore has a large capacity for supporting platinum or palladium compounds and excellent heat resistance. In addition, as these porous substances, commercially available products can be used.

BEST MODE FOR CARRYING OUT THE INVENTION

In order to prepare the adsorbent of the present invention, the above-mentioned hydrophobic zeolite loaded with the platinum and / or palladium compound in the form of fine particles, or a hydrophobic zeolite not loaded with a metal compound and others loaded with these metal compounds are used. It is prepared by slurrying the porous substance of (1) according to a conventional method and forming a coat layer on the surface of an electric heating medium such as a heater device. The slurry can be prepared by adding a dispersant, a surfactant, a thickener, a binder and the like to zeolite or the like carrying the metal compound.

The surface of the electric heating medium of the heater device is preferably aluminum, stainless steel, heat-resistant glass such as quartz glass or crystallized glass, or ceramics such as cordierite. The heat generating part of the heater device is a heater made of stainless steel, aluminum or the like, and a PTC heater whose internal resistance changes with temperature and whose temperature rises only up to about 200 ° C to 300 ° C is preferable. In addition, a heater device in which a quartz glass tube, a crystallized glass tube, or a ceramics tube such as a cordierite tube in which a metal wire such as a nichrome wire or a kanthal wire is formed into a coil shape can be used.

For these heaters, for example, a defrosting heater for a refrigerator or a heating heater for a garbage disposal may be used. As a method for applying the adsorbent to the heater device, a usual method such as a spray method, a roller method, or a dipping method can be used.
In some cases, an undercoating coating may be applied between the heater device material and the adsorbent slurry in consideration of the adhesiveness. After the slurry is applied to the electric heating medium, it can be baked at a predetermined temperature to form a robust adsorbent layer on its surface.

Since the adsorbent of the present invention contains a hydrophobic zeolite, even in an atmosphere containing water, a small amount of ammonia, mercaptans, amines, aldehydes, hydrogen sulfide, lower carboxylic acids and the like, which are malodorous components, are present. Shows high adsorptivity. In addition, the adsorbent is applied to the electric heating medium, and by heating the adsorbent that has adsorbed the malodorous gas at regular intervals, the synergistic action of the catalytic action of the platinum and / or palladium compound and the adsorptivity of the porous substance is achieved. It has a self-regeneration function that is removed by a strong oxidative decomposition action and the adsorption of malodorous substances is restored. This is the greatest feature of the adsorbent of the present invention.

The adsorbent of the present invention is an adsorbent prepared by applying only a platinum and / or palladium compound, only a porous material carrying a platinum and / or palladium compound, or only a hydrophobic zeolite to a heater device. In comparison with Example 1, Comparative Example 1 and Comparative Example 1 also have a self-regeneration function that does not exhibit high adsorptivity for malodorous components, but indicates the degree of recovery of adsorptivity by heating at regular intervals.
As you can see from 2, it is far superior.

The deodorizing mechanism of the deodorant of the present invention can be considered as follows in the case of electric appliances such as refrigerators. Malodorous gas has a high adsorption capacity for malodorous components even in an atmosphere containing water.
Sufficiently adsorbed in the operating temperature range of electrical appliances below room temperature, and the temperature of the adsorbent that adsorbed the malodorous gas rises by automatically energizing the heater device at regular time intervals. It is considered that the malodorous component is oxidized and decomposed by the synergistic action of the catalytic action and the adsorptivity of the porous substance which is the carrier of these metal compounds, and is converted into an odorless substance such as carbon dioxide and water.

Although a high temperature of 600 ° C. to a few thousand hundreds of ° C. is usually required to completely oxidatively decompose these malodorous substances without using a catalyst, the adsorbent of the present invention has platinum and / or palladium as described above. Odorous substances can be completely oxidatively decomposed in the relatively low temperature range of about 200 ° C by the action of catalysts.

Further, by completely oxidizing and decomposing the adsorbed malodorous component, the adsorption capacity can be almost completely restored to the state before use. Therefore, since the life of the adsorbent is semi-permanent, there is no need for replacement. Further, as is clear from the action of the adsorbent of the present invention, rather than using it in a place where it is constantly heated to a high temperature, it adsorbs malodorous substances at room temperature or lower, and periodically energizes the heater to increase the temperature. It is suitable to use by disassembling with.

[0034]

The present invention will be described more specifically with reference to the following examples.

(Example 1) As a carrier, a synthetic zeolite which does not correspond to the hydrophobic zeolite specified in the present invention and has a particle size of 80 mesh under powder is used. A platinum ammine complex was supported on this by an ion exchange method so that the supporting rate in terms of metallic platinum (the same applies hereinafter) was 0.5%, and calcined at 350 ° C. for 4 hours to prepare a platinum-supported zeolite. Laporte Laponite in 100 parts of water as a dispersant
The above platinum-supported zeolite in an aqueous solution containing 1.5 parts of XLG.
25 parts was added and well stirred, and 4 parts of sodium m-xylene sulfonate and 5 parts of propylene glycol were further added to prepare a slurry.

Next, molecular sieve "Absentu 200" from UOP Co., which is commercially available as a hydrophobic zeolite.
(Specific surface area 630 m ² / g, Si / Al 200 or more) was used. This was similarly prepared into a slurry by the above method.

A silica-based binder was applied to the outer surface of an aluminum heater unit (outer diameter 40 mm square) having aluminum fins attached to a tube of 300 mm in length, and the slurry of the above two kinds of adsorbents was applied thereon. The mixture was mixed at a weight ratio of 1: 1 and applied by a roller method. A sample was prepared by drying the tube at 300 ° C. while slowly raising the temperature. The total coating amount of both adsorbents was 2.0 g / line.

The obtained adsorbent sample and a PTC heater capable of maintaining a constant temperature during heating are set in an acrylic box having a volume of 1 m ³ , 15 ppm of trimethylamine is introduced therein, and a separately set air volume of 1.5 m ^{3 is} set. / min blower
I ran for 30 minutes. As a result of the test, the removal rate of trimethylamine was 87%. After the test was completed, trimethylamine remaining in the box was released to the outside of the system, and then a current was passed through the heater to keep the surface at 250 ° C. for 10 minutes.
During heating, desorption of trimethylamine and other odors was not observed from the adsorbent coating layer of the heater. Thereafter, a trimethylamine odor was introduced similarly to the above test, and an adsorption test was conducted for 30 minutes. As a result, the trimethylamine removal rate was 86%, and it was confirmed that the adsorption capacity was almost completely regenerated. This operation was repeated 5 times, but no reduction in removal rate was observed.

(Example 2) Platinum-supporting zeolite commercially available from NE Chemcat as platinum compound-supporting zeolite (silica / alumina molar ratio: 5.25, platinum-supporting ratio)
0.5%), the heater device has an outer diameter of 10 mm and a length of
A sample was prepared in the same manner as in Example 1 except that a 300 mm quartz glass tube was used. The total coating amount of both adsorbents is 0.5
It was g / book. A nichrome wire coil heater was inserted inside the quartz glass tube so that it could be heated.

As a result of performing a trimethylamine removal test in the same manner as in Example 1, the removal rate was 78%. After that, when a regeneration test was conducted in the same manner as in Example 1, the removal rate was 7
It was 7%, and it was confirmed that the adsorption capacity was regenerated.

Example 3 A sample prepared in the same manner as in Example 2 was used to carry out an acetic acid removal test. As a result, the removal rate was 90%. After that, the adsorbent was regenerated in the same manner and the acetic acid removal test was performed in the same manner as described above.
%, And it was confirmed that the adsorption capacity was regenerated.

Example 4 A sample prepared in the same manner as in Example 2 was used to perform a test for removing acetaldehyde. As a result, the removal rate was 88%. After that, after regenerating the adsorbent in the same manner, the acetic acid removal test was performed in the same manner as above,
When a regeneration test was performed, the removal rate was 88%, and it was confirmed that the adsorption capacity was regenerated.

Example 5 Using alumina powder (100 mesh under) as the porous substance, a platinum ammine complex-supported alumina having a supported amount of 5% was prepared in the same manner as in Example 1. A slurry was prepared in the same manner as in Example 1. As a hydrophobic zeolite slurry, UOP's molecular sieve "Summerlite" (specific surface area 540 m ² / g,
A slurry solution was similarly prepared using Si / Al200 or more). The two slurries were mixed at a weight ratio of 1: 1 and applied on a stainless steel heater having an outer shape of 30 mm square with fins attached to a shaft having a length of 400 mm to prepare a sample in the same manner as in Example 1. The total coating amount of both adsorbents was 4.8 g / line.

A trimethylamine removal test was conducted in the same manner as in Example 1, and as a result, the removal rate was 73%. After that, when the same regeneration test was conducted, the removal rate was 76%.
It was confirmed that the adsorption capacity was regenerated.

Example 6 A hydrophobic zeolite carrying 2% of chloroplatinic acid was prepared in the same manner as in Example 1 by using the hydrophobic zeolite "Absentu 2000". This is slurried in the same manner as in Example 1, and this slurry is provided with a 400 mm long shaft and fins attached to the outer diameter of 30 m.
The sample was prepared in the same manner as in Example 1 by applying it on a square-shaped stainless steel heater. The amount of adsorbent applied was 5.2 g / line.

As a result of a trimethylamine removal test conducted in the same manner as in the example, the removal rate was 86%. After that, when the same reproduction test was performed, the removal rate was 88%.
Next, the adsorption capacity was regenerated.

(Example 7) As a hydrophobic zeolite, a zeolite "ZSM-5" manufactured by Mizusawa Chemical Co., Ltd. (silica / alumina molar ratio)
75) was used. A platinum ammine complex and a palladium ammine complex were supported in the same manner as in Example 1 to prepare platinum and palladium-supported hydrophobic zeolite supporting platinum 1% and palladium 1%. This was slurried in the same manner as in Example 1, and this slurry was applied to a quartz glass tube electric heating element having an outer diameter of 10 mm and a length of 300 mm in the same manner as in Example 2 to prepare a sample. The amount of adsorbent applied was 0.6 g / line.

As a result of a trimethylamine removal test conducted in the same manner as in the example, the removal rate was 75%. After that, when the same reproduction test was performed, the removal rate was 74%.
Next, the adsorption capacity was regenerated.

Comparative Example 1 A sample was prepared in the same manner as in Example 1, except that the hydrophobic zeolite slurry was not used, but only the zeolite slurry carrying the platinum ammine complex was used. The amount of adsorbent applied was 2.0 g / line.

As a result of performing a trimethylamine removal test in the same manner as in Example 1, the removal rate was 39%, which was lower than the case where hydrophobic zeolite was used in combination.

Comparative Example 2 A sample was prepared in the same manner as in Example 1 except that the zeolite slurry carrying the platinum ammine complex was not used, and the hydrophobic zeolite slurry was changed to the hydrophobic zeolite "Absent 1000". Was prepared. The amount of adsorbent applied was 2.0 g / line.

As a result of performing a trimethylamine removal test in the same manner as in Example 1, the removal rate was 64%. After that, when the same reproduction test was performed, the removal rate was 44%,
The degree of adsorption recovery was insufficient.

[0053]

Industrial Applicability The malodor adsorbent of the present invention has a property that it can be repeatedly used by recovering its adsorptivity by heating. When used for deodorizing the inside of a refrigerator or food waste disposer, hydrophobic zeolite has a high ability to adsorb malodor in an atmosphere containing water, and periodic heating can improve the catalytic activity of platinum compounds and the adsorption of carriers. In combination, the odorous components are oxidatively decomposed and the adsorptivity can be restored, allowing semi-permanent use. Further, the heating power source has an advantage that the heating power source can be shared by applying an adsorbent to the surface of a defrosting heater of a refrigerator or the like.

Claims (4)

[Claims] 1. A self-regenerating adsorbent comprising a compound of platinum and / or palladium and a hydrophobic zeolite having a silica / alumina molar ratio of 70 or more and a specific surface area of 500 m ² / g or more. 2. A hydrophobic zeolite having a silica / alumina molar ratio of 70 or more and a specific surface area of 500 m ² / g or more, on which a platinum and / or palladium compound is supported, or other metal zeolite on which the metal compound is supported. A self-regenerating type adsorbent obtained by applying a mixture of a porous substance and the hydrophobic zeolite to an electric heating medium. 3. The self-regenerating type adsorbent according to claim 1, wherein the silica / alumina molar ratio of the hydrophobic zeolite is 200 or more. 4. The surface of the electric heating medium is aluminum, stainless steel, heat-resistant glass or cordierite.
And the self-regenerating type adsorbent according to claim 3.