JPH03154636A - Deodorization catalyst - Google Patents

Abstract

PURPOSE:To remove malodorous gases and harmful gases sufficiently even if the gases to be treated are relatively in low temperature by carrying and having manganese oxide and a composite oxide of silver and manganese as active components in an inorganic oxide support. CONSTITUTION:A deodorization catalyst is carried on a porous support of an inorganic oxide having at least 1m<2>/g specific surface area and contains manganese oxide and a composite oxide of silver and manganese such as AgMn2 O4 AgMnO2, AgMnO4, AgMnO, Ag2MnO, Ag2Mn8O16 as active components. The atomic ratio of Ag and Mn in the active components ranges (1:99)-(80:20)=Ag:Mn. The catalyst further contains Ag and/or silver oxide as an active component. Ceramics of a honeycomb structure, a flat substrate, or a met or a metal structure is coated with those active components. In this way, the catalyst has high removal efficiency of malodorous gases and harmful gases and sufficient deodorization function even if the gas to be treated is relatively in low temperature.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a deodorizing catalyst having a novel active ingredient,
In particular, harmful gases such as smoke and gas containing malodorous substances generated during cooking with cooking devices such as ovens, grills, and microwave ovens,
The present invention relates to a deodorizing catalyst for removing malodorous gases through catalytic combustion.

[Conventional technology]

Complaints and problems related to the living environment, such as air pollution caused by harmful and foul-smelling gases emitted from factories, river pollution, and noise from transportation, have been occurring continuously for several decades. Particularly in recent years, with changes in lifestyles such as overcrowding of houses and the desire for more comfortable living spaces, the problem of odors and sounds in the home has come into focus.

Possible sources of odor are mainly smoke generated during cooking of foods, malodorous gases, garbage, toilets, etc. Among these, the method of removing smoke and foul-smelling gases generated during cooking has been to use local exhaust ventilation using ventilation fans.

[Problem to be solved by the invention]

However, in the above-mentioned conventional method, the smoke and foul-smelling gas released into the room from the cooker are not completely exhausted to the outside, and remain and adhere to the room, causing discomfort to the people living there. In addition, even if the smoke and foul odor emitted from the cooker are simply discharged outside, similar complaints will occur in new locations.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a deodorizing catalyst that can remove harmful gases and malodorous gases, particularly smoke and malodors contained in gases generated during food cooking.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a deodorizing catalyst that is supported on an inorganic oxide carrier and contains manganese oxide and a composite oxide of silver and manganese as active ingredients. be.

In the above deodorizing catalyst, the active component can contain silver and/or silver oxide in addition to manganese oxide and a composite oxide of silver and manganese.

As a composite oxide of silver and manganese, AgMn2AgM
n204A, AgMn0n, AgMn0, A
One or more selected from gJnOl AgJneO+s. Further, the atomic ratio of silver and manganese in the active component of the catalyst is Ag:Mn 1:99 to 80:20, preferably,
The range is from 5:95 to 35:65.

In the above deodorizing catalyst, the inorganic oxide carrier is T-
Porous carriers having a specific surface area of 1 m'' and 7 g or more, such as alumina, Tie, zeolite, etc., can be suitably used.

This is because if the specific surface area of the carrier is small or small, the supported deodorizing catalyst will aggregate. The upper limit of the specific surface area is preferably 1000 m2/g. A particularly preferred range is 50 to 1000 m2/g theal.

Further, the deodorizing catalyst described above can also be used as a deodorizing catalyst structure by coating it on a ceramic or metal structure, and these structures include honeycomb shapes, plate-like substrates, wire meshes, and the like.

Next, the present invention will be explained in detail.

The catalyst of the present invention is prepared by adding ammonia to a mixed aqueous solution of water-soluble manganese salts such as silver nitrate and manganese nitrate.

It is obtained by adding an aqueous solution of a neutralizing agent such as an alkali carbonate or an alkali hydroxide, drying the coprecipitate, and then heating and oxidizing it. At this time, an oxidizing agent such as potassium permanganate may be added together with a neutralizing agent to oxidize manganese during precipitation. Alternatively, silver and manganese precipitates may be generated separately by the above method, then kneaded, dried, and then heated and oxidized. It can also be obtained by mixing and kneading silver salts or silver oxide such as silver oxalate, silver carbonate, or silver nitrate with manganese salts or manganese oxide such as manganese acetate, manganese oxalate, or manganese nitrate in a wet or dry process, and then thermally decomposing the mixture. .

These catalysts are finally obtained by heat treatment at 200° C. or higher and 900° C. or lower, preferably 300 to 600 tons, in the presence of air.

The catalyst of the present invention can also contain transition metals such as iron, cobalt, nickel, and copper, and noble metals such as platinum and palladium in addition to silver and manganese elements as active components.

The active ingredient thus prepared was analyzed by powder X-ray diffraction. The results are shown in FIG.

The diffraction peaks are generally broad. Metallic Ag and oxide A expected from the copper element contained as an active ingredient
No peaks specific to g2O are observed in this diffraction pattern. On the other hand, the manganese element contained as an active ingredient is manganese oxide Mn20. It was identified in the form of Furthermore, a very broad peak of AgMn204, which is a composite oxide of silver and manganese, was also observed. As mentioned above, since the peaks of Ag and Ag2O are not observed, the silver element does not exist in the state of a single oxide or metal, but forms a composite oxide with manganese, and is present in the manganese oxide. It is thought that it is distributed in

Depending on the composition ratio of active ingredients silver and manganese (when the silver content is high), Ag may appear in the X-ray diffraction pattern of the deodorizing catalyst.
Alternatively, it may contain a peak specific to Ag2O. However, in this case Ag.

The peak intensity of Ag2O is much lower than expected from the total amount of silver contained in the catalyst.

Therefore, from this fact as well, it can be said that silver forms a composite oxide with manganese.

The catalyst of the present invention, which is composed of an oxide containing silver and manganese as main components, can be used alone or in a porous carrier such as alumina, titania, or zeolite, or a ceramic carrier such as cordierite.

Even when used on a metal carrier such as SUS, it exhibits sufficient catalytic performance. Further, after being supported on the above-mentioned carrier, it may be further supported on a carrier such as ceramics or metal by a method such as coating.

The method for producing these catalysts involves mixing and kneading the precipitate containing silver and manganese obtained by the method described above, or the oxide or salts of silver and manganese after heat treatment, with a ceramic carrier or its precursor sol. Post-heat treatment or
For example, it is coated on a ceramic or metal carrier and then subjected to heat treatment. Alternatively, a ceramic carrier or a metal carrier may be impregnated or coated with a mixed aqueous solution of water-soluble silver salts and manganese salts, and then dried and heat-treated to precipitate a catalyst containing silver and manganese as main components.

The shapes of the catalysts produced by the above method are pellets formed from powder, honeycomb shapes, and sheet shapes.

Plates, three-dimensional foams, etc. are applicable.

[Effect]

The catalyst of the present invention is characterized in that it is composed of a catalyst containing silver and manganese as main components, and that the catalyst contains both a composite oxide of silver and manganese and manganese oxide. Manganese oxide has Mna03.0 depending on the heat treatment temperature of the catalyst. Mn5L, M
nL or a mixture thereof. A part of the manganese in the catalyst forms a composite oxide with silver. The form of the composite oxide also varies depending on the heat treatment temperature, such as AgMn20+, Ag
MnO2, AgMn01°AgMnO, Ag1Mn0.
It takes the form of either ^gzMne口, , or a mixture thereof. In particular, AgMn01 mouth.

AgMn02 is preferred.

By forming a composite oxide, the oxidation state of silver is maintained, silver is highly dispersed and agglomeration is suppressed, and when the composite oxide is mixed with manganese oxide, silver is highly dispersed. As a result, the catalyst exhibits high activity. If all the manganese in the catalyst forms a composite oxide, the catalyst will not exhibit high activity. This is because crystal growth progresses as a composite oxide, which eventually leads to agglomeration of silver. By mixing it with manganese oxide, crystal growth of the composite oxide can also be suppressed.

All of the silver in the catalyst may not be in the form of a composite oxide, but may exist in the form of silver or silver oxide.

This is because when mixed in manganese oxide, they become more thermally stable and highly active than when they exist alone.

As described above, the catalyst of the present invention contains both a composite oxide of silver and manganese and manganese oxide in the oxide, so that silver is highly dispersed and is particularly suitable for ovens.

It is effective in deodorizing foul-smelling gas containing a wide variety of components that is generated when cooking food on a grill or in a microwave oven.

In other words, the catalyst of the present invention can be used in places inside ovens, grills, ranges, etc. that come into contact with gases containing malodorous components generated during cooking, such as gas exhaust passages, their openings, and outlets that may interfere with food cooking. By being installed in a location where there is no

The catalyst of the present invention acts effectively at a reaction temperature of room temperature or higher, preferably 100°C or higher. If the temperature of the gas containing the odor generated due to the cooking temperature does not reach this temperature, it is necessary to install a heater or the like to maintain the temperature range in which the catalyst works effectively.

〔Example〕

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 29.3 g of silver nitrate and 97.6 g of manganese nitrate hole hydrate were dissolved in distilled water to prepare 400 cc of a mixed aqueous solution. A T-alumina honeycomb with a specific surface area of 150 m'/g and 100 cells/1 nch2 was immersed in this mixed aqueous solution for 2 minutes, dried at 120°C, and then heated in an air atmosphere at 500°C.
Heat treatment was performed at ℃ for 1 hour.

This operation was repeated twice to obtain a completed catalyst. The Ag:Mn (atomic ratio) of this catalyst was 30 near 0.

Example 2 Silver nitrate 8.90g, manganese nitrate hole hydrate 134.4g
A catalyst was prepared in exactly the same manner as in Example 1, except for using. The Ag:Mn ratio of this catalyst was 10:90.

Example 3 Silver nitrate 5.31g, manganese nitrate hexahydrate 80.4g
.

100g of T-alumina powder with a specific surface area of 250 m2/g
, and 40 cc of distilled water were kneaded for about 1 hour. This slurry was dried at 120°C and then fired at 500°C for 2 hours.

This oxide was classified into 200 mesh or less, and a binder and distilled water were added to form a slurry. 100 cells/1n
After coating a ch2 cordierite honeycomb with this slurry, it was dried at 120°C and fired at 500°C for 2 hours.

Comparative Example 1 A silver catalyst was prepared in exactly the same manner as in Example 1, except that 79.41 g of silver nitrate was used and manganese nitrate hexahydrate was not used.

Comparative Example 2 Not using silver nitrate, manganese nitrate hole hydrate 183
．． A manganese oxide catalyst was prepared in exactly the same manner as in Example 2 except that 27 g was used.

Comparative Example 3 Aqueous ammonia was added dropwise to a solution of 48.2 g of silver nitrate dissolved in lIl of distilled water, the resulting sol was filtered, and after drying
It was calcined at ℃ for 2 hours to obtain silver catalyst powder.

Further, aqueous ammonia was added dropwise to a solution of 75.6 g of manganese nitrate pore hydrate dissolved in distilled water in step 11, and the resulting sol was filtered, dried, and then calcined at 500° C. for 2 hours to obtain manganese oxide. Silver catalyst, manganese oxide and specific surface area 250 m'/g
T-alumina powder was mixed at a weight ratio of 3:90,
Wet kneading.

After drying, this was press-molded and classified into 40 to 138 mesh to obtain a catalyst. The X-ray diffraction of this catalyst revealed three peaks for T-alumina, Ag, and MnzL.

Above is the example 1. Example 2. Example 3. Comparative example 1. Comparative example 2. Regarding the catalyst of Comparative Example 3, Sv:aoooooh-
Removal rates were measured at reaction temperatures of 100, 200° C. and 300° C. under the following conditions: reaction gas: 60 ppm acetaldehyde, 60 ppm alimethylamine, and air-based conditions. The results are shown in FIG.

The catalysts of Examples 1, 2, and 3 have higher removal rates than the catalysts of Comparative Examples 1, 2, and 3, and have particularly high performance between 100 and 300°C. Therefore, even if the cooking temperature is low and the temperature of the malodorous gas generated is low, it exhibits effective deodorizing performance. In addition, in the case of a system in which the reaction temperature is kept high by heating the malodorous gas and the catalyst with a heater, the deodorizing effect can be exerted without the gas slipping even at low temperatures during heating of the heater.

Example 4 Silver nitrate 25.48g, manganese nitrate hole hydrate 43°06
g was dissolved in 21 distilled water to prepare a mixed aqueous solution. Ammonia water obtained by diluting concentrated ammonia water with twice the volume of distilled water was added dropwise to the above mixed aqueous solution while stirring to form a precipitate. After washing this precipitate twice by decantation,
It was filtered under suction and dried at 120°C. Heat this to 300℃
The mixture was calcined for 2 hours and used as a catalyst.

The obtained catalyst was analyzed by powder X-ray diffraction.

The results are shown in FIG. 2 as an X-ray diffraction pattern. Second
In the figure, the peak unique to Mn2L is shown, and the mark is AgMnJ.
4 shows a unique peak. This shows that this catalyst contains manganese oxide and a composite oxide of silver and manganese.

Example 5 A coating slurry was prepared in the same manner as in Example 4, except that 68.66 g of manganese acetate tetrahydrate was used instead of manganese nitrate hexahydrate.

This was coated on a SUS wire mesh sprayed with alumina, dried, and then fired at 500° C. for 2 hours. 22 sheets of this wire mesh type catalyst were piled up, SV: 30000h-', reaction gas diacetaldehyde 50ppm, )limethylamine 50ppm, reaction temperature 250 under air-based conditions.
The removal rate at °C was measured. At this time, the removal rate was 80% for acetaldehyde and 90% for trimethylamine. This wire mesh type catalyst has higher thermal conductivity than a catalyst made only of oxides, so the temperature of the catalyst layer can be quickly raised by reaction gas, a heater, etc., and it is also effective from a system standpoint.

〔Effect of the invention〕

As described above, the catalyst of the present invention has a high removal rate of malodorous gases and harmful gases, and exhibits effective deodorizing performance even when the temperature of the treated gas is relatively low.

[Brief explanation of the drawing]

Figure 1 is a graph showing acetaldehyde and trimethylamine removal rates at each reaction temperature for Example 1.2.3 and Comparative Example 1 and 2.3 catalysts. Figure 2 is an X-ray diffraction analysis of Example 4 catalyst. It is a diffraction diagram showing a pattern.

Claims (1)

[Claims] 1. A deodorizing catalyst supported on an inorganic oxide carrier and containing manganese oxide and a composite oxide of silver and manganese as active ingredients. 2. The deodorizing catalyst according to claim 1, further containing silver and/or silver oxide as an active ingredient. 3. In claim 1, the composite oxide of silver and manganese is AgMn_2O_4, AgMnO_2, AgMnO
_4, AgMnO, Ag_2MnO, Ag_2Mn_6
A deodorizing catalyst characterized by being one or more selected from O_1_6. 4. In claim 1, the atomic ratio of silver and manganese in the active component of the catalyst is Ag:Mn=1:99 to 80:20.
A deodorizing catalyst characterized by being in the range of. 5. The deodorizing catalyst according to claim 1, wherein the inorganic oxide carrier is a porous carrier having a specific surface area of 1 m^2/g or more. 6. A deodorizing catalyst structure comprising a ceramic or metal structure coated with the deodorizing catalyst according to claim 1. 7. The deodorizing catalyst structure according to claim 6, wherein the ceramic or metal structure is selected from a honeycomb structure, a plate-like base material, and a wire mesh.