JP4190047B2 - Method for oxidizing organic compounds and catalyst for aldehyde oxidation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method the oxidation of aldehydes to oxidize the aldehyde is contacted with the catalyst, and to the oxidation catalyst that may be used therewith.
[0002]
[Prior art]
Conventionally, air purifiers, deodorizers, and the like have been used for the purpose of removing tobacco odors in buildings and in automobiles. These adsorb and remove aldehydes (eg, acetaldehyde, 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, but it cannot adsorb low-molecular and high-polarity organic substances (such as acetaldehyde) sufficiently and supports activated amines, ascorbic acid, etc. Those having improved adsorption ability are used as adsorbents capable of adsorbing various organic substances.
[0003]
Examples of the amines supported thereon include those using aniline in JP-A-56-53744 and those using ethanol-based amines in JP-A-60-202735. ing.
[0004]
[Problems to be solved by the invention]
However, in the technology for supporting amines, the state is unstable, and an amine odor is often generated, and since the amines used are toxic, there is a problem of safety. On the other hand, in the case where ascorbic acid is supported, there is a problem that the use period is shortened because ascorbic acid is sublimable. Further, simply adsorbing aldehydes has a drawback in that its adsorption capacity is limited, and it is necessary to replace the adsorbent.
[0005]
On the other hand, as a method of deodorizing by oxidizing aldehyde, a method using a combination of normal manganese oxide (Mn ₂ O ₃ ) and silver is N. Watanabe et al., Applied Catalysis B, Environmental 8 (1996) 405-415. Is disclosed. However, there is a limit to the ability of ordinary manganese oxide to oxidize and deodorize. For example, in order to exert sufficient deodorizing catalytic ability, the manganese oxide must be maintained at a high temperature. It was.
[0006]
Accordingly, an object of the present invention is to provide an organic compound oxidation method and an oxidation catalyst that have few problems such as detachment of a support material, use period, and temperature limitation and that have a high effect of removing gaseous organic compounds composed of aldehydes. It is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve this object, the present inventors have intensively studied the oxidation method of organic compounds using various catalysts, and found that the above object can be achieved by using a manganate having a molecular sieve structure as a catalyst. The present invention has been completed through heading and further research.
[0008]
That is, oxidation process of the present invention are manganese having 1 or more and a divalent be that the molecular sieve structure obtained by drying the precipitate obtained by mixing the one or more manganese compounds in the permanganate compound At least one metal ion selected from the group consisting of alkali metal, alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium, cobalt, nickel, and chromium is bonded to the acid salt by ion exchange under acidic conditions It is characterized in that the gaseous organic compound is oxidized by bringing the gas containing the gaseous organic compound composed of aldehydes into contact with the resulting organic compound oxidation catalyst.
In this case, it is particularly preferable that the metal ions are silver ions or cobalt ions.
Furthermore, in the oxidation method of the present application, it is preferable to oxidize the gaseous organic compound under conditions of 100 ° C. or lower.
The organic compound oxidation catalyst of the present invention is an organic compound oxidation catalyst for oxidizing and removing gaseous organic compounds composed of aldehydes, and includes one or more permanganate compounds and one of divalent manganese compounds. the permanganate having obtained that the molecular sieve structure by drying the precipitate obtained by mixing the seeds above, under acidic conditions, by ion exchange, alkali metal, alkaline earth metal, silver, palladium, platinum And at least one metal ion selected from the group consisting of ruthenium, rhodium, cobalt, nickel, and chromium.
In this case, it is particularly preferable that the metal ions are silver ions or cobalt ions.
[0009]
[Function and effect]
And according to the oxidation method of the present invention, as shown in the results of Examples described later, the catalyst is obtained by mixing one or more permanganate compounds and one or more divalent manganese compounds. Since a manganate having a molecular sieve structure obtained by drying the resulting precipitate is used, the adsorption capacity of organic compounds (aldehydes, the same shall apply hereinafter) is relatively large, the oxidation rate is high, and the manganese in the gas to be treated The removal effect of acid salt is high. Further, since the manganate itself is non-volatile and functions as an oxidation catalyst, there are few problems such as detachment of the support material and limitation of the use period.
In addition, the molecular sieve structure of manganate is a structure suitable for the adsorption of organic compounds, and the catalyst that oxidizes various organic compounds exists in the adsorption site. This is thought to be due to its action.
Therefore, according to the method of the present invention, the catalytic action can be exhibited not under high temperature conditions such as heating to about 100 ° C. but under low temperature conditions such as room temperature. The organic compound oxidation can be realized.
[0010]
The metal ions constituting the manganese salt can be employed an alkali metal, alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium, cobalt, nickel, chromium, these metal salts, Since the metal greatly contributes to the enhancement of the catalytic action and the catalytic action is high, the oxidation rate is increased, the apparent adsorption capacity is increased, and a rapid treatment is possible.
[0011]
Therefore, according to the organic compound oxidation catalyst of the present invention, as described above, the organic compound adsorption capacity is large, the oxidation rate is fast, and the oxidation reaction having a high effect of removing the organic compound in the gas to be treated can be performed. it can. In addition, when used for deodorization or the like, there are few problems such as detachment of the support material and limitation of the period of use. In addition, the catalytic action can be exhibited even under a low temperature condition such as room temperature, and an organic compound oxidation catalyst that is extremely easy to handle can be provided.
[0012]
Metal ions constituting the manganese salt is an alkali metal, alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium, cobalt, nickel, if one or more selected from the group consisting of chromium, manganese ions It has a structure in which metal ions are bonded inside the pores of the molecular sieve structure that is composed of, and it is considered that metal ions form a structure that easily exhibits an oxidation catalytic ability at the gas adsorption site of manganic acid. Catalysis can be expected, and since the catalytic action of the bound ions is high, the oxidation rate is faster, the apparent adsorption capacity is increased, and rapid processing is possible.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[Oxidation catalyst]
The catalyst for oxidizing an organic compound of the present invention contains a manganate having a molecular sieve structure as a main component. For details on the preparation method and octahedral molecular sieve structure of such manganates, see YFShen et al., SIENCE, vol. 260 (1993) 511-515 and N. Watanabe et al., Applied Catalysis B, Environmental 8 (1996) 405-415 etc., only the outline will be described in this specification.
[0014]
Regarding the preparation method, one or more permanganate compounds and one or more divalent manganese compounds are stirred in an acidic aqueous solution having a pH of 3 or less, for example, at a temperature of 50 ° C. to 150 ° C. React for 5-10 hours to cause precipitation. When this precipitate is filtered and dried at 100 ° C. or higher (for example, 120 ° C.) for about 15 hours, a manganate having a molecular sieve structure can be obtained.
[0015]
Examples of the manganese peroxide compound used include LiMnO ₄ , NaMnO ₄ , KMnO ₄ , CsMnO ₄ , Mg (MnO ₄ ) ₂ , Ca (MnO ₄ ) ₂ , and Ba (MnO ₄ ) ₂ .
Examples of the divalent manganese compound include Mn (NO ₃ ) ₂ , MnSO ₄ , MnCl ₂ , Mn (CH ₃ COO) _{2 and the} like.
[0016]
The obtained manganate forms tunnel structures (holes) of various sizes, while the MnO ₆ octahedral chains share the ends. In the pores, monovalent or divalent cations of a type corresponding to the production method are bound and retained, but the cation species can be changed by ion exchange.
[0017]
The size of the pores is determined by the number of the chain-like materials forming the tunnel, and the 2 × 2 tunnel type (OMS-2) with two chains and the 3 × 3 tunnel type (OMS-1) with three chains Are well known, the size of the former being about 4.6A and the size of the latter being about 6.9A. However, several other types are known and can be used in the present invention.
[0018]
The above-mentioned preparation method is usually a method for obtaining OMS-2. However, when preparing OMS-1, a layered precursor is obtained by reacting the same raw materials under strong base conditions (for example, pH 13 or more). This can be obtained by aging at room temperature for 8 hours or more, ion exchange, and further heat-treating at 150 to 180 ° C. for several days.
[0019]
The organic compound oxidation catalyst of the present invention contains the above-mentioned manganate as a main component, and a part of other catalyst is mixed, or a binder component is blended to form a molded product. May be.
[0020]
In the present invention, the manganese salt as described above, alkali metals, alkaline earth metals, silver, palladium, platinum, ruthenium, rhodium, cobalt, those selected nickel, from the group consisting of chromium Preferably, especially silver Those obtained by ion-bonding ions are preferable because the reaction rate is high.
[0021]
In order 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 or the like, and about 50 to 95 ° C. The ion exchange may be performed for about 5 to 20 hours.
[0022]
In the present invention, it is also possible to partially substitute manganese, which is a metal forming the tunnel skeleton, with other metals, and transitions of 3A, 4A, 5A, 6A, 7A, 8A, 1B, and 2B in the periodic table. One or more types are selected from metals. Various hydrates exist and any of them can be used in the present invention.
[0023]
[Oxidation method]
The method for oxidizing an aldehyde of the present invention is to oxidize an aldehyde by contacting with the above-mentioned catalyst. A specific reaction method can be performed using various apparatuses according to a normal catalytic contact oxidation reaction. For example, any method such as a method in which a gas containing an aldehyde is circulated through a column packed with a catalyst, a catalyst formed into a honeycomb shape, or a gas and a catalyst are brought into contact with each other 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 incorporated into a honeycomb shape or impregnated into a woven fabric, non-woven fabric, paper or the like.
[0024]
As the reaction conditions, the reaction rate increases as the reaction is performed at a higher temperature. The reaction rate is about 22% at 100 ° C., and the reaction rate at 100 ° C. is about 98%.
[0025]
In addition, the usage-amount of a catalyst, contact time, etc. are suitably determined according to the flow volume, aldehyde density | concentration, etc. of raw material gas.
[0026]
【Example】
EXAMPLES Hereinafter, examples and the like showing specific configurations and effects of the present invention will be described, but the present invention is not limited to these.
[0027]
Production Example 1
In a flask, 40 parts by weight of KMnO ₄ which is a manganese peroxide compound and 60 parts by weight of MnSO ₄ which is a divalent manganese compound are mixed with 400 parts by weight of ion-exchanged water, and sulfuric acid is added thereto. The pH was adjusted to 2.0, and the mixture was reacted at a temperature of 100 ° C. for 1 hour with stirring to cause precipitation. This precipitate was filtered, washed with ion exchange water, and dried at 120 ° C. for about 15 hours to obtain potassium manganate having the octahedral molecular sieve structure of the present invention. (Substance material before reaching the present invention).
The structure of this potassium manganate was very similar to the hollandite ore from the XRD chart shown in FIG. 7, and was found to be a manganate having an OMS-2 structure.
[0028]
Production Example 2
Using the manganate obtained in Production Example 1, manganese oxide in which silver ions were ion-bonded into the pores of the octahedral molecular sieve structure was obtained by the following operation. (Invention of the present application).
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 manganate was added thereto, ion exchange was performed at 90 ° C. for 12 hours. This was filtered with a filter paper, washed with ion-exchanged water, and then dried at 120 ° C. for 15 hours to obtain a silver ion-exchanged manganese oxide according to the present application .
The ion exchange was confirmed by chemical quantitative analysis of the residual silver ion concentration in the filtrate.
[0029]
Example 1-1
The silver ion exchange manganate according to the present invention obtained in Production Example 2 was incorporated into the 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, in the test apparatus used, the cylinder 3 contains nitrogen gas containing 1000 ppm of acetaldehyde, and the cylinder 4 contains air. The concentration is appropriate for the reaction system via the filters 6 and 5 and the valves V1 to V7. The gas can be circulated. The temperature of the reaction tube 1 can be adjusted, the catalyst 2 is filled inside, 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.
[0030]
As measurement conditions, 0.35 g of the manganate formed into 1 to 2 mm is filled in the reaction tube 1, and a bypass is used so that the acetaldehyde concentration is 100 ppm and the gas flow rate is 10 L / hr. The opening degree of each valve V1-V4 was adjusted.
The reaction was continuously performed at 50 ° C. for 900 minutes, 100 ° C. for 120 minutes, and 75 ° C. for 280 minutes. FIG. 2 shows the change over time in the outlet concentration at which acetaldehyde breaks through the test apparatus.
[0031]
The results in FIG. 2 show the following findings.
The reason that the outlet concentration of acetaldehyde is close to 0 at the beginning of the reaction is that aldehyde is mostly trapped mainly by adsorption, and when the reaction time exceeds 100 minutes, the outlet concentration gradually increases due to adsorption saturation. When the reaction time exceeds 600 minutes, the outlet concentration becomes almost constant (about 77 ppm), which indicates the outlet concentration in a steady state and serves as an indicator of the reaction rate. When the reaction temperature is set to 100 ° C. in 900 minutes, the outlet concentration rapidly decreases to about 2 ppm because the reaction rate of the catalytic reaction is increased and the adsorbed aldehyde is rapidly oxidized and decomposed. That is, the adsorption capacity should decrease at higher temperatures. When the reaction temperature is increased to 75 ° C. in 1020 minutes, the outlet concentration gradually increases, and when it exceeds 1300 minutes, the removal rate becomes substantially constant (about 60 ppm), indicating a steady state reaction rate.
[0032]
In Reference Example Example 1-1 , instead of continuously changing the reaction temperature using potassium manganate produced according to Production Example 1, which is a substance in the previous stage for producing the silver ion-exchanged manganate according to the present application the reaction temperature is kept constant, various reaction temperatures (25 ℃, 55 ℃, 100 ℃) except that the reaction is carried out in, examine all in the same manner as in example 1 -1 the time course of the reaction rate of acetaldehyde as a reference (See FIG. 3). Moreover, about the time-dependent change of the acetaldehyde removal ability at room temperature, it performed referring to the comparison with a normal deodorant (refer FIG. 4).
The removal ability was evaluated based on the outlet concentration (breakthrough curve) when 100 ppm of acetaldehyde-containing air was supplied at 10 L / h to 0.35 g of the catalyst (or deodorizer) at each temperature.
According to FIG. 3, it can be seen that the manganate exhibits a high removal ability even at room temperature and a higher activity as the temperature increases (in the activated carbon deodorizer, the performance decreases as the temperature increases).
As can be seen from the results in FIG. 4, the manganate has high organic substance removal performance, and it is understood that high performance is maintained even after 300 minutes.
In addition, the used catalyst or adsorbent is as follows.
Mn-OMS: manganate potassium obtained in Production Example 1
BET specific surface area of about 200 m ² / g
ACF (OG): Activated carbon fiber, Osaka Gas Co., Ltd. (comparative product)
BET specific surface area of about 1000 m ² / g
Activated carbon (N): Nacalai Tesque Co., Ltd. 1 set product M8T1311 (comparative product)
BET specific surface area of about 1000 m ² / g
Note that mere manganese dioxide shows only a higher outlet concentration than various activated carbons, and it can be seen that the characteristics of the molecular sieve structure of manganate greatly contribute to the catalytic function.
[0033]
Example 1-2
In Example 1 -1, instead of changing continuously the reaction temperature, the reaction temperature was constant (25 ° C.), except that the reaction is carried out using various catalysts or adsorbent, as in Example 1 -1 Similarly, the change with time of the outlet concentration of acetaldehyde was examined.
In addition, 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 of about 200 m ² / g
ACF (OG): Activated carbon fiber, Osaka Gas Co., Ltd. (comparative product)
BET specific surface area of about 1000 m ² / g
The result is 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 reached 90 ppm or more in 200 minutes or 250 minutes. On the other hand, the product of the present invention maintains the outlet concentration at approximately 0 until 150 minutes at the beginning of the reaction, and can maintain an outlet concentration (90 ppm relative to 100 ppm) lower than the input gas concentration in a steady state.
[0034]
Example 1-3
In Example 1-1 , instead of continuously changing the reaction temperature, the reaction temperature was kept constant (25 ° C.), and after 600 minutes had elapsed, the gas supply was stopped for 24 hours, and then the reaction temperature (25 ° C. ) Except that the reaction was carried out in the same manner as in Example 1-1, and the change with time in the removal rate of acetaldehyde was examined.
The result is shown in FIG.
As shown in the results of FIG. 6, the removal rate is constant at about 10% after 600 minutes, but the removal rate has recovered to 50% after being left for 24 hours. This is thought to be because the aldehyde adsorbed during standing was oxidized and removed, and the adsorption capacity was newly recovered accordingly.
[Brief description of the drawings]
Figure [Figure 1 shows the time course of removal capability in Figure 3 shows the reference example shows the time course of the removal rate in schematic diagram Figure 2 Example 1 -1 of the test apparatus used in Examples 4 illustrates the time course of removal rate in FIG. 6 examples 1-3 showing the time course of removal rate in FIG. 5 shows example 1-2 showing the time course of removal ability in reference example [ FIG. 7 is a diagram showing an XRD analysis structure of OMS-2 in Production Example 1
1 reaction tube 2 catalyst 8 gas chromatograph

Claims (5)

The permanganate having 1 or more and a divalent be that the molecular sieve structure obtained by drying the precipitate obtained by mixing the one or more manganese compounds in the permanganate compound, under acidic conditions, A catalyst for oxidizing an organic compound obtained by binding at least one metal ion selected from the group consisting of alkali metal, alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium, cobalt, nickel, and chromium by ion exchange. ,
By contacting a gas containing gaseous organic compound consisting of aldehydes, oxidation process of organic compounds to oxidize the gaseous organic compounds.   The method for oxidizing an organic compound according to claim 1, wherein the metal ions are silver ions or cobalt ions.   The method for oxidizing an organic compound according to claim 1 or 2, wherein the gaseous organic compound is oxidized under a condition of 100 ° C or lower. An organic compound oxidation catalyst for oxidizing and removing gaseous organic compounds composed of aldehydes,
The permanganate having 1 or more and a divalent be that the molecular sieve structure obtained by drying the precipitate obtained by mixing the one or more manganese compounds in the permanganate compound, under acidic conditions, A catalyst for oxidizing an organic compound obtained by binding at least one metal ion selected from the group consisting of alkali metal, alkaline earth metal, silver, palladium, platinum, ruthenium, rhodium, cobalt, nickel, and chromium by ion exchange.   The catalyst for oxidizing an organic compound according to claim 4, wherein the metal ions are silver ions or cobalt ions.

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