JP3470496B2 - Deodorization treatment method using ozone - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel deodorizing method of oxidizing or decomposing odorous components in gas by ozone in the presence of a catalyst, and particularly to houses, offices, hospitals, factories, amusement parks, in-vehicles. The present invention relates to a deodorizing method of oxidizing or decomposing unpleasant odorous components such as the like with ozone at a temperature near room temperature.

[0002]

2. Description of the Related Art As the standard of living environment rises, there is an increasing demand for the removal of a trace amount of unpleasant odorous components existing in houses, offices, hospitals, factories, playgrounds, cars, etc.

Known methods for removing odorous components in gas include oxidative decomposition using a catalyst, a method using an adsorbent, and an ozone oxidation method. The oxidative decomposition method using a catalyst is described in, for example, Japanese Patent Application Laid-Open No. 4-200638, but there is a problem that the catalyst does not work unless the temperature of the processing gas is raised. As such, it is not suitable for those that need to be treated near room temperature.

The method using an adsorbent and the ozone oxidation method are
Although it is suitable for removing a small amount of odorous components at room temperature, the method using an adsorbent requires replacement of the adsorbent, which is problematic in terms of cost. The ozone oxidation method has a problem that it takes a long time to react a dilute malodorous component with ozone in a gas phase, and unreacted ozone is exhausted to cause secondary pollution.

Under the above circumstances, a deodorizing method has recently been proposed in which ozone and a malodorous component are reacted in the presence of a catalyst to oxidize or decompose the malodorous component. This method is disclosed in, for example, Japanese Unexamined Patent Publication No. 4-322726, Japanese Unexamined Patent Publication No. 5-49863,
No. 7-41146.

[0006]

The method of accelerating the reaction between ozone and odorous components using a catalyst is effective as a method for removing odorous components of low concentration. The present invention is to further improve this method, and to provide an improved method of oxidizing and decomposing low-odor odorous components with low-concentration ozone.

The odorous component concentration in the living space is usually 1 ppm or less. The concentration of ozone is 0.1ppm
But it feels uncomfortable for normal people and most people have nose,
I feel irritation in my throat. For this reason, an ozone concentration of 0.1 ppm is considered to be an acceptable concentration for occupational health. The present invention provides a deodorizing method capable of oxidizing and decomposing low-concentration odorous components with low-concentration ozone and reducing the emission concentration of excess ozone to 0.1 ppm or less.

[0008]

The present invention provides a deodorizing treatment method in which a gas containing an odor component and ozone is brought into contact with a catalyst to oxidize or decompose the odor component, and the ozone concentration in the gas is adjusted to 0.05 to 5 ppm. And the space velocity of gas treatment by the catalyst is in the range of 60,000 to 300,000 per hour, and the catalyst containing silver and manganese is used to oxidize and decompose odorous components by ozone under room temperature conditions.

The catalyst used in the deodorizing method of the present invention is
It has a structure in which the active ingredient is supported on the surface of the carrier, contains silver and manganese as the active ingredient in an atomic ratio of 1:10 to 1: 2, and the supported amount of the active ingredient on the carrier is 1 to oxide. It is preferably 20% by weight.

In the method of the present invention, the ozone concentration in the gas of 0.05 to 5 ppm is a necessary condition for efficiently deodorizing odorous components having a concentration of 1 ppm or less. Even if the concentration of the odorous component in the living environment becomes higher than 1 ppm and the amount of ozone in the gas for decomposing or oxidizing the odorous component may be insufficient at a certain moment, the silver used in the method of the present invention The catalyst containing manganese as an active component has an effect of adsorbing an odorous component that cannot be completely treated by a reaction with ozone, and therefore an unreacted odorous component does not flow out. When the ozone concentration is higher than the odor component concentration, the odor component adsorbed by the catalyst containing silver and manganese as active components reacts with ozone to be decomposed or oxidized and removed from the catalyst. That is, a catalyst containing silver and manganese as active components has a kind of dam-like effect, and does not necessarily require controlling the ozone concentration in response to changes in the odorous component concentration.
Further, since the activity of decomposing excess ozone is high, ozone is hardly emitted.

The catalyst containing silver and manganese as active ingredients used in the method of the present invention, especially the catalyst consisting of two active ingredients of silver and manganese, exhibits sufficient deodorizing performance even when the ozone concentration is 5 ppm or less, and 1 ppm or less. It shows high activity even at low levels. If the ozone concentration is higher than this range, there is a risk that excess ozone that did not react with the odorous component may be decomposed and flow out. The ozone concentration at the outlet of the catalyst layer is preferably 0.1 ppm or less, and for that purpose, the ozone concentration at the inlet is preferably 5 ppm or less, particularly 1 ppm.
ppm or less is preferable. If the ozone concentration is in the high concentration range of 10 ppm or more, the discharged ozone concentration becomes high, which is not preferable.

In the method of the present invention, the space velocity of gas treatment by the catalyst (the amount of gas treated per unit catalyst volume for one hour) is preferably in the range of 60,000 to 300,000 per hour. Since the gas containing the odorous component can be treated at a high space velocity as described above, the catalyst capacity can be small and the treatment device can be made compact.

The catalyst used in the deodorizing method of the present invention is most preferably an active ingredient consisting of two components, silver and manganese, but other components contained in the raw materials and the like during the preparation of the catalyst are mixed. Does not refuse The atomic ratio of silver to manganese is preferably silver: manganese of 1:10 to 1: 2. If the content ratio of silver and manganese is outside this range, the performance of ozone deodorization reaction and the decomposition activity of excess ozone are low. Also, the durability of the catalyst is low. Further, the amount of the active ingredient supported on the carrier is preferably 1 to 20% by weight in terms of oxide, and when it exceeds this range, high deodorization in a low ozone concentration region and a high space velocity, which is a feature of the present invention. The effect and decomposition effect of excess ozone cannot be obtained.

As the carrier of the catalyst used in the method of the present invention, alumina, silica, zeolite, cordierite,
A porous carrier having a specific surface area of 1 m ² / g or more, typified by titania, is suitable. When using a carrier having a small specific surface area, it is preferable to coat a porous material in advance.

The catalyst used in the present invention may be coated on a ceramic or metal substrate to form a catalyst structure, or may be coated after the catalyst component is supported on the porous carrier powder. As the base material, a honeycomb-shaped or plate-shaped material is used.

The typical methods for preparing the catalyst of the present invention are shown below, but the invention is not limited thereto.

As starting materials for silver and manganese, compounds such as oxides, hydroxides, carbonates, nitrates, chlorides, acetates, oxalates and alkoxides can be used. As the preparation method, usual impregnation method, deposition method, kneading method,
A coprecipitation method or the like can be used and is not particularly limited. That is,
A method of impregnating or kneading a raw material solution of these components, preferably an aqueous solution into a carrier, followed by drying and firing, or addition of ammonia water or the like to a mixed solution of these component raw materials to generate a hydroxide precipitate After that, a method of performing drying and baking, mixing with a carrier powder, and molding can be applied.
Further, a method in which a powder of a carrier is added to a raw material solution, an alkali such as ammonia is added to the raw material solution while being sufficiently mixed, and the mixture is deposited on the carrier, followed by drying and firing, is also applicable. In this case, calcination is preferably performed in air at 300 to 600 ° C.

Incidentally, these catalysts are molded into an appropriate shape before use. The shape is not particularly limited, but a columnar shape, a spherical shape, a plate shape, a honeycomb shape or the like is preferable.

The silver element of the catalyst thus prepared forms a compound of oxygen or a compound of oxygen and a manganese element. That is, silver is not precipitated in the metallic state but is in the oxidized state as an electronic state. Usually, in the case of a single silver catalyst, silver oxide releases oxygen at a temperature of about 200 ° C. or higher, so that it precipitates as metallic silver at a preferable calcining temperature of 300 to 600 ° C. for the catalyst of the present invention. However, in the catalyst of the present invention, manganese oxide keeps silver in an oxidized state by the oxide having a lower oxidation number than MnO _{2 which} is usually stable, that is, the oxidation number is lower than +4.

Manganese exists mainly in the form of either Mn ₂ O ₃ or Mn ₃ O ₄ or a mixture of both.
Part of the silver in the catalyst forms a complex oxide with manganese.
The morphology of the complex oxide depends on the heat treatment temperature,
n ₂ O ₄ , AgMnO ₂ , AgMnO ₄ , AgMnO ₃ , A
It takes the form of any one of g ₂ MnO ₂ and Ag ₂ Mn ₉ O ₁₆ or a mixture thereof. As a result, the catalyst becomes highly active in the ozone deodorizing reaction, and silver is highly dispersed and aggregation is suppressed.

The compound form of silver and manganese elements of the catalyst is
It can be identified by powder X-ray diffraction, and the electronic state is identified by a general analysis method such as X-ray photoelectron spectroscopy.

It is considered that maintaining appropriate oxidation states of silver and manganese as described above is one of the factors that maintain high activity as an ozone deodorizing catalyst.

An air purifier is an example of a product to which the ozone deodorizing catalyst of the present invention is applied. In that case, an ozone generating mechanism is required in addition to the deodorizing catalyst, and it is preferable to further include a dust removing mechanism, but it is also possible to use without a dust removing mechanism. Another application is an air conditioner. The air conditioner is usually provided with a heating function, a cooling function, a dehumidifying function, a humidifying function, and the like. In addition to these functions, the ozone deodorizing catalyst of the present invention can be incorporated to provide the deodorizing function. In that case, an ozone generating mechanism is also required. That is, as a product to which the deodorizing method of the present invention is applied, a dust removing mechanism and an ozone generating mechanism are provided, and an air purifier equipped with the deodorizing mechanism of the present method, an air conditioning mechanism and an ozone generating mechanism are provided, and the deodorizing mechanism of the present method is provided. There is an air conditioner equipped with.

In the treatment of a gas containing a low concentration odorous component by the method of the present invention, ozone is first mixed with the gas to be treated and then the catalyst is ventilated. As described above, the conditions for contacting the catalyst and the gas to be treated are room temperature conditions, and the space velocity (SV) of the gas is 60,000 to 300,000 per hour. Particularly, 60,000 to 200,000 per hour is preferable. When used with an SV of less than this, the catalyst capacity becomes large and the processing air volume becomes small. Further, if the SV exceeds 300,000, the deodorizing effect and the effect of decomposing excess ozone are not sufficient even with this catalyst.

In the method of the present invention, odorous components can be efficiently deodorized under room temperature conditions, specifically in the temperature range of 0 to 50 ° C., and heating for reacting odorous components with ozone is particularly required. do not do. However, when the temperature in the room is 15 ° C. or lower, it is particularly desirable to heat it to some extent and raise it to 20 ° C. or higher.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 32.9 g of silver nitrate and 500 g of manganese nitrate hexahydrate were dissolved in distilled water to make 1 liter. Honeycomb-shaped cordierite carrier (150mm square,
A thickness of 50 mm and 210 cells / in 2) was impregnated with this mixed aqueous solution. After drying this at 120 ° C., it was heated in an air atmosphere at 500 ° C. for 2 hours to obtain a catalyst. At this time, the composition ratio (atomic ratio) of silver (Ag) and manganese (Mn), which are active ingredients, was Ag: Mn = 1: 9, and the amount of the active ingredient supported was 5% by weight based on the carrier. It was

Assuming a living space containing odorous components, a reactor filled with one of the above catalysts is installed in an acrylic box having a length, width, and height of 2 m, which is filled with air containing 10 ppm of odorous components. The gas in the box was passed through the catalyst by a fan at room temperature at a flow rate of 3.75 m ^{3 /} min. At this time, ozone was generated by an ozonizer and added to the gas before passing through the catalyst to a concentration of 1 ppm. The space velocity at this time was 200,000 per hour. The deodorizing effect was examined by sampling the gas in the box at regular intervals and analyzing the concentrations of odorous components. As typical examples of odorous components, five kinds of acetaldehyde, trimethylamine, ammonia, methyl mercaptan and hydrogen sulfide were used. The deodorization rate was calculated according to the following formula.

[0029]

[Equation 1]

Table 1 shows the deodorization rate 10 minutes after the start of the reaction.
As is clear from Table 1, this catalyst exhibits a high deodorizing effect on various malodorous components.

In this case, the ozone concentration at the catalyst layer outlet was 0.05 ppm or less in all cases.

[0032]

[Table 1]

Example 2 Ag was produced in the same manner as in Example 1.
And the composition ratio of Mn is atomic ratio Ag: Mn = 1: 10, 1:
A cordierite honeycomb-supported Ag-Mn catalyst of 5,1: 3,1: 2 was prepared. Also, for comparison, Mn10
A catalyst having 0% catalyst and 100% Ag and a catalyst having a composition ratio of Ag and Mn of 1:15, 1: 1 outside the range of the present invention was also prepared. In each case, the supported amount is 5% by weight in terms of oxide.

Table 2 shows the deodorization rate 10 minutes after the start of the reaction.
However, here, acetaldehyde was used as the odor component.

As is clear from Table 2, the addition of a small amount of silver greatly increases the deodorizing effect as compared with the manganese single catalyst, and the ratio of Ag and Mn within the range of the present invention is suitable. I understand. Silver according to an embodiment of the present invention - the structure of the manganese catalyst was examined by powder X-ray diffraction method, peaks of Mn ₃ peak of the O ₄ and Ag ₂ O and AgMn ₂ O ₄ was observed. On the other hand, the manganese single catalyst is MnO ₂ ,
The silver single catalyst was a crystalline form of Ag (metal state). Thus, by selecting the optimum composition for the Ag-Mn two-component catalyst, it is considered that one of the causes for exhibiting a high activity due to the crystal structure different from that of the single catalyst due to the combined effect.

[0036]

[Table 2]

Example 3 An Ag-Mn supported catalyst was prepared in the same manner as in Example 1 except that titania or alumina honeycomb was used as the carrier instead of the cordierite honeycomb carrier, and the ozone deodorization test was conducted. However, here, ammonia was used as the odor component.

Table 3 shows the deodorization rate 10 minutes after the start of the reaction.
As is clear from Table 3, the present catalyst shows a high effect on ozone deodorization even if the carrier is changed.

[0039]

[Table 3]

[Example 4] The same as Example 1 except that the loading amount of the active ingredient on the cordierite honeycomb carrier was changed to 0.5, 1, 2, 10, 20, 30 wt% based on the oxide. An Ag-Mn supported catalyst was prepared by the method, and an ozone deodorization test was conducted. However, methyl mercaptan was used as the odor component here. Table 4 shows the deodorization rate 10 minutes after the start of the reaction. As is clear from Table 4, a high deodorizing effect was exhibited in a wide range of the supported amount of the active ingredient from 1 to 20% by weight.

[0041]

[Table 4]

[Embodiment 5] In this embodiment, the result of examining the relationship between the inlet ozone concentration and the outlet ozone concentration when the space velocity is changed is shown. Using the catalyst used in Example 1,
While changing the space velocity by changing the processing gas air volume,
The acetaldehyde deodorization reaction was carried out in the same manner as in Example 1 while changing the inlet ozone concentration. The acetaldehyde concentration was 1 ppm.

FIG. 1 shows the ozone concentration at the catalyst layer outlet 10 minutes after the start of the reaction. In all cases, acetaldehyde was removed by 90% or more.

As is clear from FIG. 1, in order to reduce the exhaust ozone concentration to 0.1 ppm or less, it is preferable that the inlet ozone concentration is 5 ppm or less and the space velocity is 300,000 or less per hour. It turns out to be preferable.

[0045]

According to the present invention, a house, an office, a hospital,
It is possible to efficiently oxidize or decompose low-concentration odorous components existing in living spaces such as factories, amusement parks, and cars in the vicinity of room temperature with low-concentration ozone, remove bad odors, and suppress the ozone concentration discharged.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an inlet ozone concentration and an outlet ozone concentration.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Yamashita 7-1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Shingo Ichiki Nakajo-machi, Kitakanbara-gun, Niigata 46 Tomioka Address 1 Hitachi Ltd., Production Equipment Division (56) Reference JP-A-8-71361 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 21/00-37/36 B01D 53/86 A61L 9/00

Claims (4)

(57) [Claims] 1. A deodorizing treatment method in which a gas containing an odor component and ozone is brought into contact with a catalyst to oxidize or decompose the odor component, and the ozone concentration in the gas before being brought into contact with the catalyst is 0.0.
The range of 5 to 5 ppm, the space velocity of gas treatment with a catalyst within the range of 60 to 300,000 per hour , the compound of silver and oxygen and the compound of silver, oxygen and manganese.
At least the at least one of and Mn ₂ O ₃ and Mn ₃ O ₄
A method for deodorizing treatment with ozone, which comprises contacting a catalyst containing one form of manganese oxide with the gas under room temperature conditions. 2. The carrier according to claim 1, wherein the catalyst has a structure in which an active component is supported on the surface of a carrier, and contains silver and manganese as active components in an atomic ratio of 1:10 to 1: 2. The deodorizing treatment method using ozone, wherein the supported amount of the active ingredient is 1 to 20% by weight in terms of oxide. 3. The method for deodorizing treatment with ozone according to claim 2, wherein the active ingredient is composed of two components, silver and manganese. 4. A deodorizing method for oxidizing or decomposing an odor component by bringing a gas containing an odor component and ozone into contact with a catalyst, and at least one of a compound of silver and oxygen and a compound of silver, oxygen and manganese and Mn. _A method for deodorizing treatment by ozone, which comprises bringing a catalyst containing a manganese oxide in the form of at least one of ₂ O ₃ and Mn ₃ O ₄ into contact with the gas.