JPH02107338A - Catalyst for decomposing contaminated gas and its usage - Google Patents

Abstract

PURPOSE:To decontaminate gases easily, accurately and efficiently by depositing catalytic components capable of photodecomposing and/or heat decomposing contaminated gases on a carrier capable of being heated to thereby prepare a catalyst for decomposing the contaminated gases. CONSTITUTION:The catalitic components capable of photodecomposing and/or heat decomposing contaminated gases are deposited on a carrier cable of being heated by a heat source such as SiC, BaTiO3, stabilized zirconia, various perovskite oxides and Ni-Cr to thereby prepare a catalyst for decomposing the contaminated gas. By way of example, active carbon is available as the catalystic component capable of adsorbing the contaminated gas and titanium oxide as the catalitic component capable of photodecomposing the same. The catalyst so formed is irradiated with light and heated upon regeneration, whereby the adsorbed contaminants can be decomposed and removed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to equipment for removing pollutant gases, and in particular to an air purifying catalyst body suitable for deodorizing air circulation systems such as refrigerators and air conditioners. Regarding.

[Conventional technology]

Conventionally, as a method of deodorizing refrigerators, air conditioners, etc., a method using a deodorizing agent such as activated carbon has been generally performed. In addition to the method of using adsorbents such as activated carbon, methods of decomposing these harmful components through an oxidation catalyst layer are also used for polluting gases, ie, bad smells and harmful gases discharged from each S manufacturing factory. In this case, it is necessary to heat the exhaust gas to be treated above the temperature at which the catalyst works effectively, but there is a method to increase efficiency by heating the catalytic converter itself with electricity using a honeycomb-shaped heating element in the catalyst layer. (%
No. 55-22890) has also been proposed. In addition, a method has been proposed in which harmful gases are treated by irradiating a gas containing nitrogen oxides with ultraviolet rays in the presence of titanium oxide or zinc oxide (%KAI No. 61155125). A method of oxidatively decomposing malodorous components (Japanese Patent Application Laid-open No. 60289/1983) has also been proposed.

[Problem to be solved by the invention]

Although each of the above-mentioned conventional techniques has advantages, they often have drawbacks such as insufficient removal efficiency of malodorous components, excessive consumption of electrical energy, and large flames in the apparatus.

An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a catalyst for decomposing polluted gas that can easily, reliably, and efficiently remove polluted gas, and its uses.

[Means to solve the problem]

To summarize the present invention, the first invention of the present invention relates to a catalyst for decomposing pollutant gas, and the present invention relates to a catalyst body for decomposing pollutant gas, in which
It is characterized in that a catalyst capable of photolyzing pollutant gas and/or a catalyst capable of thermally decomposing pollutant gas is supported.

The second invention is an invention related to a contaminated gas removal device,
The catalyst is characterized in that a material having the ability to adsorb pollutant gas is supported on the above-mentioned catalyst body.

A fifth invention is an invention relating to another contaminated gas removal device, in which the device adsorbs contaminated gas disposed upstream of the contaminated gas-containing stream. It is characterized in that it is made of a combination of a material having the ability to

A fourth invention is an invention relating to equipment that requires the removal of polluted gas, and in which the polluted gas removal device of the second or fifth invention is installed at a location in the equipment where a stream containing polluted gas flows. −[Characterized by being.

A fifth invention relates to a method of using the polluted gas removal device, comprising: passing a stream containing polluted gas through the polluting gas removal device of the second or third invention for a predetermined period of time to adsorb polluted gas; Thereafter, the adsorbent is heated to liberate the adsorbed pollutant gas, and the catalyst body of the first invention is irradiated with light and/or heated to decompose the liberated pollutant gas for a predetermined period of time for regeneration. It is characterized by

The substrate used in the present invention is, for example, a heat-generating material made of a material that generates heat when heated. Typical examples include ceramics having a commonly known honeycomb structure, mesh structure, or laminated structure of plates. /or a metal body is used. The material is not particularly limited, but in order to achieve the purpose of the present invention, a heat source or the like, such as one that generates heat by electricity, is required, such as SiC%BaTi0m, stabilized zirconia, various perovskite oxides, Ni-C.
r etc. can be used.

In addition, in the present invention, the heating and/or light irradiation of the catalyst body does not need to be performed continuously, but is performed after a sufficient period of time after the adsorption capacity has decreased due to adsorption of contaminant components to the adsorbent, or just before the adsorption capacity decreases. If you do it intermittently, you can achieve your goal.

An example of the material having the ability to adsorb pollutant gases used in the present invention is activated carbon, and an example of the catalyst having the photodecomposition ability is titanium oxide. The effect is greater when these components are mixed well with each other. In order to improve the performance, various metal oxides such as MOo, WOh8nO1, ZnO1
Sulfides, e.g. zns.

It is also good to add CaS or a noble metal, such as pt%P(L, Ru, etc.).Also, a method of coating the inner wall of the through hole of the base with a substance having a high specific surface area such as alumina or silica, and then coating the catalyst component is also possible. good.

In addition, in the present invention, various thermal decomposition catalyst components, such as noble metals such as PT and PA, are used to improve thermal decomposition of polluting components, especially malodorous components, such as thermal oxidative decomposition by heating during regeneration of the catalyst body. It is also good to add manganese oxide, cobalt oxide, nickel oxide, iron oxide, various perovskites, etc. to the catalyst. When the adsorption capacity of a catalyst body containing these additive components decreases, it is possible to regenerate the catalyst by simply applying electric current and heating, and may even omit light irradiation.

Further, when regenerating the catalyst, it is possible to perform the regeneration while flowing a gas such as air, or it can be performed while a gas containing a low concentration of malodorous components is being flowed.

Of course, it is also possible to perform this without flowing gas. Furthermore, if the catalyst activity is strong, only one of light irradiation and heating may be used.

[For production]

In the present invention, contaminant components, such as malodorous components (eg, hydrocarbons, sulfur compounds, nitrogen compounds, etc.), are first adsorbed and removed by an adsorbent in the catalyst body. Activated carbon is preferred as one of the adsorbent components. When the adsorption of contaminant components to the adsorbent becomes saturated, the adsorbent loses its function and needs to be replaced or regenerated. In the present invention, since the catalyst component which has the photodecomposition activity or thermal decomposition activity of the pollutant component is contained in the catalyst body simultaneously with or subsequently to the adsorbent component, the catalyst body is irradiated with UV light, preferably ultraviolet light, at the time of regeneration. By doing so and/or by heating, the contaminant components adsorbed on the adsorbent are decomposed and removed. Therefore, the adsorption capacity of the catalyst body (or adsorbent) is restored and it can be used repeatedly to remove contaminant components.

In this case, if the catalyst body consists only of an adsorbent, the purifying effect is lost after a certain amount of contaminant components have been adsorbed and removed, as described above.

Furthermore, with only the photocatalyst component, the efficiency is poor because the contaminant components are not decomposed unless light is constantly irradiated during the process gas flow, but in the method of the present invention, the light irradiation only needs to be done intermittently.
Energy efficient.

Furthermore, one embodiment of the present invention is characterized in that the substrate of these adsorption-photodecomposition catalysts is made of a material made of ceramics and/or metal that generates heat when energized. During regeneration, in addition to light irradiation, the substrate is heated by electricity to raise the temperature of the catalyst, so that the contaminant components adsorbed to the adsorbent component are desorbed and moved toward the photolysis catalyst component, making them more likely to be decomposed. Efficiency is good because decomposition due to oxidation is more likely to occur.

In this case, as with light irradiation, heating is required only when the catalyst is regenerated, so the power consumption is lower than the conventional method of decomposing pollutants in the catalyst by constant electrical heating while flowing process gas. It is economical. It can also be applied to devices and appliances where heating is not desirable, such as refrigerators.

Examples of devices suitable for using the pollutant gas removal device of the present invention include refrigerators, air conditioners, air purifiers, and exhaust gas purifiers.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 20m integrated base made of BaT103
A honeycomb with a size of 20 cm, a length of 20 cm, and a cell count of ~40 cells/crn was prepared. This honeycomb-like substrate was immersed in a slurry containing activated carbon and titanium oxide in a ratio of 1=1, and the excess slurry was removed. After that, it was dried at 150°C for 2 hours, and then calcined in air at 500°C for 2 hours.The amount of coating at this time was approximately 20% by weight based on the substrate.The catalyst was placed in a box-shaped reaction tank. However, as a substitute example for malodorous gas components, dimethyl sulfide at 1100 pp and a simulated gas of residual air were flowed at a rate of 2 t/min, and dimethyl sulfide was analyzed on the inlet and outlet sides.At first, the dimethyl sulfide concentration on the outlet side was analyzed. was below the detection limit, but dimethyl sulfide began to flow out to the outlet after about 60 minutes.
It was found that saturated adsorption was reached. Therefore, the honeycomb surface was irradiated with 250 nm ultraviolet light using a xenon lamp, and electricity was applied to the honeycomb surface to heat the substrate to 200 to 500°C.
was heated for 10 minutes. After the dimethyl sulfide adsorbed on the catalyst was desorbed and decomposed in this way, the simulated gas was flowed again and the dimethyl sulfide adsorption test was repeated. As a result, the amount of adsorption from the second time onwards was approximately 85% of the amount adsorbed during the first test.
It was found that the catalyst body was almost regenerated by light irradiation and electrical heating, and that it could be used repeatedly.

Comparative Example 1 In a test similar to Example 1, we investigated the performance of only light irradiation and no electrical heating during regeneration, and found that the regeneration of the adsorbent was insufficient, and the adsorption amount for the second time was about 50% less than the first time.
%. Moreover, although sb and kana were regenerated by 65% of the initial rate during the second adsorption using only electrical heating, the regeneration was not sufficient compared to when light irradiation was also performed.

Example 2 In this example, a honeycomb made of SiC and having 20 x 20 cells, 20 cm in length, and 40 cells/cry' was prepared. This honeycomb-like substrate is mixed with activated carbon and titanium oxide in a ratio of 1:1.
After soaking in the slurry contained in step 1 and cutting off excess slurry, drying at 150°C for 2 hours, then soaking in the air at 500°C.
It was baked at ℃ for 2 hours.

The amount of coating at this time is approximately 10 times the weight of the substrate.
It is Chi. The performance of this catalyst was tested in the same manner as in Example 1. As a result, 200 ~ by energization after saturated adsorption
The adsorption capacity of the catalyst was easily recovered by heating at 300° C. and irradiation with ultraviolet light, and the adsorption amount from the second to the tenth times reached approximately 85% or more of the first time.

Comparative Example 2 A catalyst body was prepared in which the SiC honeycomb substrate of Example 2 was coated with 10% of activated carbon alone, and the dimethyl sulfide removal performance was tested in the same manner as in Example 1. As a result, the recovery of the adsorption performance of the catalyst by heating at 200 to 300°C by energization and irradiation with ultraviolet light after saturated adsorption was not sufficient, and the second adsorption 1-Fi was only 45% of the first time.
It was nothing more than

Therefore, it can be seen that it is necessary to also contain a catalyst component having photocatalytic activity.

Comparative Example 5 A catalyst body was prepared by coating the Sl, C honeycomb substrate of Example 2 with 10% of titanium oxide, and the catalyst body of Example 1 was prepared.
Dimethyl sulfide removal performance was tested in the same manner as in 7. As a result, dimethyl sulfide leaked out to the outlet side in about 5 minutes. These results revealed that titanium oxide alone has a low adsorption capacity for malodorous components and is not practical.

Example 3 An integrated substrate is based on a Ni-Cr plate with At on the surface.
A honeycomb with a size of 20 m x 20 cm, a length of 20 m, and a number of cells of 40/- was prepared using a substrate onto which the material was thermally sprayed. This honeycomb-shaped substrate was immersed in a slurry prepared using commercially available activated alumina, pulled up, and then dried at 00°C for 2 hours.
Thereafter, it was fired at 500°C for 2 hours. When this operation was repeated four times, about 20 wt'Ik% of alumina was deposited. This alumina-coated honeycomb was immersed in the slurry containing activated carbon and titanium oxide in a 1:1 ratio used in Example 1, and after draining off the excess slurry, it was dried at 150°C for 2 hours, and then in air. It was baked at 500°C for 2 hours.

The amount of coating at this time is approximately 10% by weight based on the base material.
It is.

This catalyst body was tested in the same manner as in Example 1.

As a result, approximately 3
It was found that the adsorption amount was sufficient even after 0 minutes. Also,
By subsequent heating at 500 to 400°C by energization and irradiation with ultraviolet light, the adsorption and removal performance of dimethyl sulfide almost recovered, and the amount of adsorption after the second time was about 85% of the first time, indicating that it can be used repeatedly. Ta.

Example 4 The honeycomb-shaped substrate made of the SiC material used in Example 2 was coated with a slurry containing activated carbon, titanium oxide, and zinc oxide in a ratio of 50:40:10, and then fired in air at 500° C. for 2 hours. At this time, the coating ijk is approximately 10 times thicker than the substrate.

The performance of this catalyst was tested in the same manner as in Example 1.

As a result, the adsorption capacity of the catalyst was easily recovered by heating at 200 to 300°C by energization after saturated adsorption and irradiation with ultraviolet light, and the adsorption amount after the second adsorption reached 90% or more of the first adsorption amount. was.

Example 5 In this example, a test was conducted in the same manner as in Example 1 except that methyl mercaptan was used in place of dimethyl sulfide as the malodorous component. As a result, in the case of methyl mercaptan, it was possible to adsorb and remove it as efficiently as in the case of dimethyl sulfide, and it was also possible to regenerate it by heating with electricity and irradiating with ultraviolet light.

Example 6 The same catalyst body used in Example 1 was immersed in an aqueous solution of chloroplatinic acid and ruthenium chloride, and then pulled up.
Dry at 50℃ for 2 hours, then dry at 500℃2 in a hydrogen stream.
Time processed. Platinum and ruthenium were each supported in an amount of 1% by weight in terms of metal. This catalyst body was used in Example 1.
The performance was tested in the same manner. As a result, the recovery of the adsorption capacity of the catalyst by electrical heating and ultraviolet light irradiation after saturated adsorption was higher than in Example 1, and the second adsorption amount Fi1
The adsorption amount was approximately 90% of the adsorption amount for the first time.

Example 7 In this example, in order to increase the ability to oxidize and decompose malodorous components by heating with electricity, 50% of each of manganese oxide, cobalt oxide, nickel oxide, and iron oxide were added to the same catalyst body as in Example 1.
A heavily loaded catalyst body was prepared. Thereafter, performance was tested in the same manner as in Example 1. As a result, in all the catalyst bodies, the adsorption capacity of the catalyst body was well recovered by electrical heating and ultraviolet light irradiation after saturated adsorption, and the adsorption amount in the second time was 85% or more of that in the first time. In addition, these catalyst bodies have enhanced oxidative decomposition function of malodorous components, so even with only electric heating without light irradiation, the regeneration of kana is progressed, and both catalyst bodies have 2
The amount of adsorption for the first time was 70 to 75% of that for the first time.

〔Effect of the invention〕

According to the present invention, contaminant components in gas, particularly malodorous components, can be efficiently decomposed and removed. In particular, it is possible to efficiently regenerate the catalyst body (adsorbent).

Patent applicant: Hitachi, Ltd.

Claims (1)

[Claims] 1. A polluted gas characterized in that a catalyst capable of photolyzing polluted gas and/or a catalyst capable of thermally decomposing polluted gas is supported on a heat-generating substrate. Catalyst for decomposition. 2. The catalyst for decomposing polluted gas according to claim 1, wherein the substrate is made of a material that generates heat when heated. 3. The base is made of ceramics and/or materials that generate heat when energized.
The catalyst for decomposing polluted gas according to claim 1, which is made of a metal or a metal. 4. A pollutant gas removal device, characterized in that the catalyst body according to claim 1 supports a material having the ability to adsorb pollutant gas. 5. A polluted gas removal device installed in a stream containing polluted gas, wherein the device comprises a material having the ability to adsorb polluted gas disposed upstream of the stream containing polluted gas, and a material disposed downstream of the stream containing polluted gas. A pollutant gas removal device characterized by comprising a combination of a catalyst body and a catalyst body. 6. A device that requires the removal of contaminated gas, characterized in that the contaminated gas removal device according to claim 4 or 5 is installed at a location where a stream containing contaminated gas flows. 7. The device according to claim 6, wherein the device is a refrigerator, an air conditioner, an air purifier, or an exhaust gas purifier. 8. The pollutant gas-containing stream is passed through the pollutant gas removal device according to claim 4 or 5 for a predetermined period of time to adsorb the pollutant gas, and then the adsorbent is heated to liberate the adsorbed pollutant gas, and the method of claim 1 A method of using a pollutant gas removal device, which comprises regenerating the liberated pollutant gas by irradiating the catalyst with light and/or heating it to decompose the released pollutant gas for a predetermined period of time. 9. The method of use according to claim 8, wherein the heating is performed by a heated gas flow and/or an electric current generating heat.