JPH11276862A - Oxidation of organic compound and catalyst for oxidizing aldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the effect on the removal of a gaseous organic compound with almost no disconnection of a bearing material and almost no limiting of use period and temperature by bringing one or more kinds of gaseous organic compounds selected from aldehydes, carboxylic acids and amines into contact with a manganate with a molecular sieve structure. SOLUTION: One or more kinds of permanganate compounds and one or more kinds of divalent manganese compounds are caused to react with each other at a specified temperature for a specified time while being stirred together with an aqueous acidic solution, and a sediment generated is filtered and dried to obtain a manganate having an octahedral molecular sieve structure. One or more kinds of metal ions selected from the group of those of an alkaline metal, an alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium, copper, cobalt, nickel and chromium, are bonded by an ion exchange in pores in the molecular sieve of the manganate. Consequently, a high oxidation catalytic action is displayed. Thus, it is possible to achieve a high oxidation rate and a high effect on the removal of an organic compound contained in a gas to be treated, and further, temperature or the like during deodorizing by the use of this method are nearly not limited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for oxidizing an aldehyde or the like by bringing the aldehyde or the like into contact with a catalyst, and an oxidation catalyst usable for the method.

[0002]

2. Description of the Related Art Conventionally, air purifiers, deodorants and the like have been used for the purpose of removing tobacco odor in the interior of a building or the interior of an automobile. These adsorb and remove aldehydes (for example, acetaldehyde and formaldehyde), which are the main components of tobacco odor, and various adsorbents are used. Activated carbon has long been known as a material that adsorbs various organic substances. However, low-molecular, highly polar organic substances (such as acetaldehyde) cannot be sufficiently adsorbed, and activated carbon is loaded with amines or ascorbic acid. What has improved adsorption ability is used as an adsorbent capable of adsorbing various organic substances.

[0003] Examples of amine-supported ones include those using aniline in JP-A-56-53744 and those using ethanol-based amines in JP-A-60-202735 and the like. Is disclosed.

[0004]

However, in the technique for supporting amines, the state of the amines is unstable and often produces an amine odor, and some of the amines used are toxic. As a result, safety issues arise. On the other hand, in the case of supporting ascorbic acid, there is a problem that the use period is shortened due to the sublimability of ascorbic acid. Also, simply adsorbing aldehydes has a limitation in its adsorption capacity, and has the disadvantage that it is necessary to replace the adsorbent.

On the other hand, as a method of deodorizing by oxidizing an aldehyde, a method using a combination of ordinary manganese oxide (Mn ₂ O ₃ ) and silver is disclosed in N. Watanabe et al., Applied Catalysi.
s B, Environmental 8 (1996) 405-415. However, there is a limit to the catalytic activity of oxidative deodorization by ordinary manganese oxide.For example, in order to exert sufficient catalytic activity for deodorization, there is no choice but to limit the manganese oxide to a high temperature. Was.

Accordingly, an object of the present invention is to provide a method for oxidizing an organic compound and a catalyst for oxidizing, which have less problems such as separation of a supported substance, use period, and temperature limitation, and have a high effect of removing gaseous organic compounds. To provide.

[0007]

Means for Solving the Problems In order to achieve this object, the present inventors have conducted intensive studies on the oxidation method of organic compounds using various catalysts. As a result, the present inventors have found that a manganate having a molecular sieve structure is used as a catalyst. As a result, the present inventors have found that the above object can be achieved, and have further studied to complete the present invention.

That is, the oxidation method of the present invention is characterized in that at least one kind of gaseous organic compound selected from aldehydes, carboxylic acids, and amines is oxidized by contact with a manganate having a molecular sieve structure, The manganic acid preferably contains at least one ion selected from the group consisting of alkali metals, alkaline earth metals, silver, palladium, platinum, ruthenium, rhodium, copper, cobalt, nickel and chromium. The catalyst for oxidizing an organic compound is characterized by containing a manganate having a molecular sieve structure as a main component, wherein the manganate is an alkali metal, an alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium. , Copper, cobalt,
It is desirable that it contains at least one ion selected from the group consisting of nickel and chromium.

According to the oxidation method of the present invention, a manganate having a molecular sieve structure is used as the catalyst as shown in the results of the examples described below.
The adsorption capacity of organic compounds is relatively large, the oxidation rate is high, and the effect of removing manganate in the gas to be treated is high.
In addition, since the manganate itself is non-volatile and functions as an oxidation catalyst, there are few problems such as separation of a supported substance and limitation of a use period. It is noted that such an effect is exhibited
It is considered that the molecular sieve structure of manganate is a structure suitable for the adsorption of organic compounds, and metal ions are present at the adsorption site, and it has a catalytic action to oxidize various organic compounds. . Therefore, according to the method of the present invention, it is possible to exert a catalytic action even under a low temperature condition of about room temperature, instead of a high temperature condition of heating to about 100 ° C. Organic compound oxidation can be realized.

As the metal ions constituting the manganate, alkali metals, alkaline earth metals, silver, palladium, platinum, ruthenium, rhodium, copper, cobalt, nickel, chromium and the like can be used. The metal salt greatly contributes to enhancing the catalytic action of the metal,
Due to the high catalysis, the oxidation rate is higher, the apparent adsorption capacity is larger, and rapid processing is possible.

Therefore, according to the catalyst for oxidizing organic compounds of the present invention, as described above, the oxidation reaction has a large adsorption capacity for organic compounds, a high oxidation rate, and a high effect of removing organic compounds from the gas to be treated. It can be carried out. Also,
When used for deodorization and the like, there are few problems such as detachment of the supported substance and limitation of the use period. Further, for example, a catalytic action can be exerted even under a low temperature condition of about room temperature, and an organic compound oxidation catalyst which is extremely easy to handle can be provided.

If the metal ion constituting the manganate is at least one selected from the group consisting of alkali metals, alkaline earth metals, silver, palladium, platinum, ruthenium, rhodium, copper, cobalt, nickel and chromium. The structure is such that metal ions are bonded in the pores of the molecular sieve structure composed of manganate ions, and at the gas adsorption site of manganate, a structure is formed in which metal ions easily exert oxidation catalytic ability. It is conceivable that a high catalytic action can be expected, and the catalytic action of the bound ion is high, so that the oxidation rate is increased, the apparent adsorption capacity is increased, and rapid processing is possible.

[0013]

Embodiments of the present invention will be described below. [Oxidation Catalyst] The organic compound oxidation catalyst of the present invention contains manganate having a molecular sieve structure as a main component. For details such as the preparation method of such manganate and the octahedral molecular sieve structure, see YFShen et al., SIEN
CE, vol. 260 (1993) 511-515 and N. Watanabe et al., Appl.
Since it is described in ied Catalysis B, Environmental 8 (1996) 405-415, etc., only an outline is described in this specification.

As to the preparation method, one or more permanganate compounds and one or more divalent manganese compounds are
For example, the reaction is carried out at a temperature in the range of 50 ° C. to 150 ° C. for 0.5 to 10 hours while stirring with an acidic aqueous solution having a pH of 3 or less to generate a precipitate. The precipitate is filtered and
After drying for about 15 hours at the above (for example, 120 ° C.),
A manganate having a molecular sieve structure can be obtained.

As the manganese peroxide compound used
Is, for example, LiMnO_Four , NaMnO _Four , KMnO_Four ,
CsMnO_Four , Mg (MnO_Four )_Two , Ca (MnO_Four )
_Two , Ba (MnO_Four )_Two And the like. Also divalent
Examples of the manganese compound include Mn (NO_Three )_Two ,
MnSO_Four, MnCl_Two , Mn (CH_Three COO)_Two Such
Is mentioned.

The obtained manganates have various sizes of tunnel structures (pores) while octahedral chains of MnO ₆ share ends. In the pores, monovalent or divalent cations of the type corresponding to the production method are bound and held, but the cation type can be changed by ion exchange.

The size of the hole is determined by the number of the chain-like substances forming the tunnel, and is a 2 × 2 tunnel type (OMS-2) having two chains and a 3 × 3 tunnel type (OMS-type) having three chains. The size of the former is about 4.6A, and the size of the latter is about 6.9A. However, some other types are also known and can be used in the present invention.

The above-mentioned preparation method is usually a method for obtaining OMS-2, but when preparing OMS-1, the same raw materials are reacted under strong base conditions (for example, pH 13 or more) to form a layered precursor. A body can be obtained by aging at room temperature for 8 hours or more, ion-exchanging, and further heat-treating at 150 to 180 ° C. for several days.

The catalyst for oxidizing an organic compound of the present invention contains the above-mentioned manganate as a main component, and further contains a binder component for partially mixing other catalysts or forming a molded article. Or you may.

In the present invention, as described above, the manganate is selected from the group consisting of alkali metals, alkaline earth metals, silver, palladium, platinum, ruthenium, rhodium, copper, cobalt, nickel and chromium. Preferably
In particular, those in which silver ions are ion-bonded are preferable because the reaction rate is high.

To form various metal salts, the ion exchange method is used as described above. For example, manganese oxide having an octahedral molecular sieve structure is added to an aqueous solution of silver nitrate, cobalt nitrate, cobalt acetate, etc. 5 at about 95 ° C
The ion exchange may be performed for about 20 hours.

In the present invention, it is possible to partially replace manganese, which is a metal forming the tunnel skeleton, with another metal, and it is possible to substitute 3A, 4A, 5A, 6A, 7A,
One or more are selected from 8A, 1B, and 2B transition metals. There are also various hydrates, all of which can be used in the present invention.

[Oxidation Method] The aldehyde oxidation method of the present invention involves oxidizing an aldehyde by contacting it with the above-mentioned catalyst. A specific reaction method can be performed using various apparatuses according to a usual catalytic catalytic oxidation reaction. For example, any method such as a method in which a gas containing an aldehyde is passed through a column filled with a catalyst or a catalyst formed in a honeycomb shape, or a method in which a gas is brought into contact with a catalyst without actively generating a flow. Can be adopted. In particular, in order to remove the tobacco odor, it is preferable that the air purifier is formed into a honeycomb shape, or is impregnated into a woven fabric, a nonwoven fabric, paper, or the like, and incorporated.

As for the reaction conditions, the higher the temperature, the faster the reaction rate. For example, when the reaction rate (removal rate) at 25 ° C. is about 12% in a steady state under the conditions of Examples described later. , At 55 ° C., about 22%, and at 100 ° C., about 98%.

The amount of the catalyst used, the contact time, and the like are appropriately determined according to the flow rate of the raw material gas, the aldehyde concentration, and the like.

[0026]

EXAMPLES The present invention will be described below with reference to examples showing specific structures and effects of the present invention, but the present invention is not limited to these examples.

Production Example 1 In a flask, a manganese peroxide compound, KMnO
₄ 40 parts by weight and MnSO which is a divalent manganese compound
And ₄ 60 parts by weight, was mixed with 400 parts by weight of ion-exchanged water, was added thereto sulfuric acid was adjusted to pH = 2.0, under stirring, allowed to react for 1 hour at a temperature 100 ° C., a precipitate I let it. This precipitate was filtered, washed with ion-exchanged water, and dried at 120 ° C. for about 15 hours to obtain potassium manganate having an octahedral molecular sieve structure of the present invention. The structure of the potassium manganate is represented by XR shown in FIG.
From the D chart, it is very similar to hollandite ore, OM
It turned out that it is a manganate of S-2 structure.

Production Example 2 Using the manganate obtained in Production Example 1, manganese oxide having silver ions ion-bonded in pores of an octahedral molecular sieve structure was obtained by the following procedure. That is, 21 parts by weight of silver nitrate and 400 parts by weight of ion-exchanged water were put into a flask to form an aqueous solution. After 100 parts by weight of a manganate was added thereto, ion exchange was performed at 90 ° C. for 12 hours. This is filtered with filter paper, washed with ion exchanged water,
After drying at 120 ° C. for 15 hours, silver ion-exchanged manganese oxide was obtained. The ion exchange was confirmed by a chemical quantitative analysis of the residual silver ion concentration in the filtrate.

Example 1 The silver ion-exchanged manganate obtained in Production Example 2 was incorporated into a test apparatus shown in FIG. 1, and the acetaldehyde removal rate corresponding to the elapsed time was measured while changing the reaction temperature. That is, the test equipment used is 100
Nitrogen gas containing 0 ppm acetaldehyde, air in cylinder 4
Through V7, a gas of an appropriate concentration can be passed through the reaction system. The temperature of the reaction tube 1 can be adjusted, the inside thereof is filled with the catalyst 2, and the reaction gas or bypass gas is introduced into the gas chromatograph device 8 from the autosampler 7, and the gas concentration is measured.

As measurement conditions, 0.35 g of the above-mentioned manganate which was formed into a size of 1 to 2 mm was filled in the reaction tube 1, and the bypass was controlled so that the acetaldehyde concentration was 100 ppm and the gas flow rate was 10 L / hr. The degree of opening of each of the valves V1 to V4 was adjusted by using this. The reaction is performed at 50 ° C for 9
00 minutes, 100 ° C. for 120 minutes, and 75 ° C. for 280 minutes were continuously performed. FIG. 2 shows the change with time of the outlet concentration at which acetaldehyde breaks through the test apparatus.

The results of FIG. 2 show the following findings. The reason why the outlet concentration of acetaldehyde is close to 0 at the beginning of the reaction is that almost all aldehydes are trapped by adsorption, and when the reaction time exceeds 100 minutes, the outlet concentration gradually increases due to adsorption saturation. Reaction time 60
After 0 minute, the outlet concentration becomes almost constant (approximately 77 ppm), which indicates the outlet concentration in a steady state and is an index of the reaction rate. Reaction temperature 10
At 0 ° C., the outlet concentration drops sharply to about 2 ppm because the reaction rate of the catalytic reaction is increased and the adsorbed aldehyde is rapidly oxidatively decomposed. That is,
At higher temperatures, the adsorption capacity should decrease. 10
When the reaction temperature is increased to 75 ° C. in 20 minutes, the outlet concentration gradually increases, and after 1300 minutes, the removal rate is almost constant (about 6%).
0 ppm), indicating a reaction rate in a steady state.

Example 2 Instead of continuously changing the reaction temperature in Example 1, the reaction temperature was kept constant and various reaction temperatures (25 ° C.,
Except for carrying out the reaction at 55 ° C. and 100 ° C.), the time-dependent change in the reaction rate of acetaldehyde was examined in the same manner as in Example 1 (see FIG. 3). In addition, the change over time in the ability to remove acetaldehyde at room temperature was compared with a normal deodorant (see FIG. 4). At each temperature, the removal capacity was 100 ppm per 0.35 g of catalyst (or deodorant).
The acetaldehyde-containing air was supplied at a rate of 10 L / h and evaluated by the outlet concentration (breakthrough curve). According to FIG. 3, it can be seen that the manganate shows a high removal ability even at room temperature and shows a higher activity as the temperature increases (the performance of the activated carbon deodorant decreases as the temperature increases). As shown in the results of FIG. 4, it can be seen that the manganate has high organic matter removal performance, and that it maintains high performance even after 300 minutes. The used catalyst or adsorbent is as follows. Mn-OMS: potassium manganate obtained in Production Example 1 (product of the present invention) BET specific surface area: about 200 m ² / g ACF (OG): activated carbon fiber, manufactured by Osaka Gas Co., Ltd. (comparative product) BET specific surface area: about 1000 m ² / g Activated carbon (N): One set of M8T1311 manufactured by Nacalai Tesque Co., Ltd. (comparative product) BET specific surface area of about 1000 m ² / g In the case of simple manganese dioxide, only the outlet concentration is higher than that of various activated carbons. It can be seen that the characteristics of manganate having a molecular sieve structure greatly contribute to the catalytic function.

Example 3 The procedure of Example 1 was repeated except that the reaction temperature was kept constant (25 ° C.) and the reaction was carried out using various catalysts or adsorbents, instead of continuously changing the reaction temperature. In the same manner as in Example 1, the change with time in the outlet concentration of acetaldehyde was examined. The used catalyst or adsorbent is as follows. Ag-Mn-OMS: silver manganate obtained in Production Example 2 (product of the present invention) BET specific surface area: about 200 m ² / g ACF (OG): activated carbon fiber, manufactured by Osaka Gas Co., Ltd. (comparative product) BET specific surface area Approximately 1000 m ² / g The results are shown in FIG. As shown in the results of FIG. 5, although the comparative product had a large specific surface area, the outlet concentration started to increase from the beginning of the reaction, and the outlet concentration became 90 ppm or more in 200 minutes or 250 minutes. On the other hand, in the product of the present invention, the outlet concentration is maintained at almost 0 up to 150 minutes in the early stage of the reaction, and in the steady state, the outlet concentration lower than the input gas concentration (90 ppm relative to 100 ppm) can be maintained.

Example 4 In Example 1, instead of continuously changing the reaction temperature, the reaction temperature was kept constant (25 ° C.), and after 600 minutes, the gas supply was stopped for 24 hours and the reaction was continued. Except for carrying out the reaction at a temperature (25 ° C.), the time-dependent change in the acetaldehyde removal rate was examined in the same manner as in Example 1. FIG. 6 shows the result. As shown in the results of FIG.
After 600 minutes, the removal rate is constant at about 10%, but the removal rate has recovered to 50% after standing for 24 hours. This is considered to be because the adsorbed aldehyde was oxidized and removed during standing, and the adsorbing ability was newly recovered by that amount.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a test apparatus used in an embodiment.

FIG. 2 is a diagram showing a change over time in a removal rate in Example 1.

FIG. 3 is a graph showing the change over time in the removal ability in Example 2.

FIG. 4 is a graph showing a change over time in the removal ability in Example 2.

FIG. 5 is a diagram showing a change over time in a removal rate in Example 3.

FIG. 6 is a graph showing a change over time in a removal rate in Example 4.

FIG. 7 is a view showing an XRD analysis structure of OMS-2 in Production Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tube 2 Catalyst 8 Gas chromatograph

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Zhang Huamin 17 Nakadoji Minamicho, Shimogyo-ku, Kyoto, Kyoto Prefecture Inside the Kansai Research Institute of Technology (72) Inventor Kenji Saeki 17 Nakadoji Minami-cho, Shimogyo-ku, Kyoto, Kyoto Kansai New Technology Laboratory Co., Ltd.

Claims (4)

[Claims] An organic compound that oxidizes a gaseous organic compound by contacting a gas containing at least one gaseous organic compound selected from aldehydes, carboxylic acids, and amines with a manganate having a molecular sieve structure. Oxidation method. 2. The method according to claim 1, wherein the manganate is an alkali metal, an alkaline earth metal, silver, palladium, platinum, ruthenium,
The method for oxidizing an organic compound according to claim 1, comprising at least one or more ions selected from the group consisting of rhodium, copper, cobalt, nickel, and chromium. 3. A catalyst for oxidizing an organic compound containing as a main component a manganate having a molecular sieve structure of at least one gaseous organic compound selected from aldehydes, carboxylic acids and amines. 4. The method according to claim 1, wherein the manganate is an alkali metal, an alkaline earth metal, silver, palladium, platinum, ruthenium,
The organic compound oxidation catalyst according to claim 3, wherein the catalyst contains at least one ion selected from the group consisting of rhodium, copper, cobalt, nickel, and chromium.