VOC removal catalyst, its manufacturing method, and VOC removal method

Abstract

To provide a VOC removal catalyst that can be easily produced, has excellent VOC removal efficiency, and can efficiently remove VOC even at low temperatures and a method for producing the same, as well as a VOC removing method.SOLUTION: A method for producing a VOC removal catalyst in the present invention includes a step 1 for mixing an oxidizer containing Mn with a metal organic structure containing a metal element M to make a precursor and a step 2 for firing the precursor made in the step 1 to make a metal oxide containing Mn. The inventive VOC removal catalyst at least contains a metal oxide containing Mn, the metal oxide containing the Mn element of 1-35 mol%, and the metal oxide having a BET specific surface area of 50-5002 / g.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a VOC removal catalyst, a method for producing the same, and a method for removing VOCs. Regarding. [Background technology]

[0002] VOC is an abbreviation for volatile organic compounds, and known examples include toluene, xylene, benzene, ethyl acetate, methanol, and dichloromethane. While such VOCs are widely used in solvents, adhesives, chemical raw materials, etc., they have been pointed out as a cause of photochemical oxidants or suspended particulate matter (SPM), and therefore their emissions are strictly regulated by the Air Pollution Control Act. For this reason, there is a need to establish technology to more efficiently remove VOCs in order to further reduce VOC emissions.

[0003] A catalytic oxidation method is known as a technique for removing VOCs. This method is considered the most promising because it removes VOCs at relatively low temperatures. Because catalytic oxidation methods mainly use transition metal oxides, they are more cost-effective than noble metal catalysts, and from this perspective, research into improving the catalytic performance of transition metal oxides has been widely conducted. For example, Patent Document 1 discloses a technique for efficiently removing VOCs using a material containing manganese (IV) oxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-147131 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional VOC removal catalysts are still not sufficient in VOC removal performance in low-temperature environments, and their production also requires time, so overall, there are still challenges to overcome when considering practical application. From these perspectives, there is currently a need for the development of a catalyst that can be easily produced and can efficiently remove VOCs even at low temperatures.

[0006] The present invention has been made in view of the above, and aims to provide a VOC removal catalyst that is easy to produce, has excellent VOC removal efficiency, and can efficiently remove VOCs even at low temperatures, a method for producing the same, and a method for removing VOCs. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above object, the present inventors have found that the above object can be achieved by using a specific Mn-based metal oxide as an essential component, or by using a Mn-based metal oxide produced through a specific process as an essential component, and have thus completed the present invention.

[0008] That is, the present invention includes, for example, the subject matter described in the following sections. Item 1 A method for producing a VOC removal catalyst, Step 1 of obtaining a precursor by mixing an oxidizing agent containing Mn with a metal organic framework containing a metal element M; Step 2: calcining the precursor obtained in step 1 to obtain a metal oxide containing Mn; A method for producing a VOC removal catalyst, comprising: Section 2 Item 2. The method according to item 1, wherein the metal element M is at least one selected from the group consisting of transition metals and rare earth elements. Section 3 Item 3. The method according to Item 2, wherein the metal element M is at least one selected from the group consisting of Mn, Ce, La, Sm, Fe, Co, Ni, Cu, and Ho. Section 4 4. The method according to any one of items 1 to 3, wherein the metal oxide containing Mn contains 1 to 35 mol % of Mn element. Section 5 A VOC removal catalyst, Contains a metal oxide containing at least Mn, The metal oxide contains 1 to 35 mol % of Mn element, The BET specific surface area of ​​the metal oxide is 50 to 500 m 2 / g of VOC removal catalyst. Section 6 The metal oxide is a composite oxide further containing a metal element M (excluding Mn), Item 6. The VOC removal catalyst according to Item 5, wherein the metal element M is at least one selected from the group consisting of transition metals and rare earth elements. Section 7 Item 7. The VOC removal catalyst according to Item 6, wherein the metal element M is at least one selected from the group consisting of Ce, La, Sm, Fe, Co, Ni, Cu, and Ho. Section 8 Item 8. The method according to item 6 or 7, wherein the composite oxide contains 5 to 40 mol % of the metal element M. Section 9 A method for removing VOCs, comprising a step of decomposing VOCs using the VOC removal catalyst obtained by the production method according to any one of Items 1 to 4 or the VOC removal catalyst according to any one of Items 5 to 8. [Effects of the Invention]

[0009] The VOC removal catalyst of the present invention is easy to produce, has excellent VOC removal efficiency, and can efficiently remove VOCs even at low temperatures. Furthermore, the method for producing the VOC removal catalyst of the present invention allows the above-mentioned VOC removal catalyst of the present invention to be produced in a simple manner. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the flow of an evaluation test method for a VOC removal catalyst. [Figure 2] 1 shows SEM images of the VOC removal catalysts obtained in Examples 1 to 3 and Comparative Examples 1 and 2. [Figure 3] 1 shows XRD spectra of the VOC removal catalysts obtained in Examples 1 to 3 and Comparative Examples 1 and 2. [Figure 4] 1 shows the results of a VOC removal test using the VOC removal catalysts obtained in Examples 1 to 3 and Comparative Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "consist essentially of," and "consist only of."

[0012] 1. Manufacturing method of VOC removal catalyst The production method of the present invention includes the following steps 1 and 2. Step 1: A step of obtaining a precursor by mixing an oxidizing agent containing Mn with a metal organic framework containing a metal element M. Step 2: A step of calcining the precursor obtained in step 1 to obtain a metal oxide containing Mn.

[0013] A VOC removal catalyst containing a metal oxide can be produced by a production method including steps 1 and 2. Such a VOC removal catalyst has excellent VOC removal efficiency and can efficiently remove VOCs even at low temperatures.

[0014] (Process 1) Step 1 is a step for obtaining a precursor by mixing an oxidizing agent containing Mn (hereinafter simply referred to as "oxidizing agent") and a metal organic framework containing a metal element M (hereinafter simply referred to as "metal organic framework agent"). Specifically, in step 1, the metal organic framework is etched by the oxidizing agent.

[0015] The oxidizing agent used in step 1 may be, for example, a wide variety of compounds containing Mn and having oxidizing properties, and specific examples thereof include permanganates. Among these, the oxidizing agent containing Mn is preferably potassium permanganate (KMnO4, K2MnO4, etc.), and more preferably KMnO4.

[0016] The metal organic framework used in step 1 is not particularly limited as long as it contains a metal element M. Metal organic frameworks (MOFs) are known as three-dimensional microporous materials that have a porous coordination network structure with a surface area far exceeding that of activated carbon or zeolite, due to the interaction between metal and organic ligands.

[0017] In the metal organic framework, various metal elements can be used as the metal element M. The metal element M is, for example, at least one selected from the group consisting of transition metals and rare earth elements, and among these, in order to enable the VOC removal catalyst to decompose VOCs at a lower temperature, the metal element M is preferably at least one selected from the group consisting of Mn, Ce, La, Sm, Fe, Co, Ni, Cu, and Ho, more preferably at least one selected from the group consisting of Co, Ni, and Cu, and particularly preferably Co.

[0018] The metal organic framework can be, for example, a wide variety of known metal organic frameworks, as long as it contains a metal element M. Specific examples of such a metal organic framework, when the metal element M is Co, include ZIF-67 (2-methylimidazole cobalt salt), Co(MeIM)2 (MEIM means 2-methylimidazole; the same applies hereinafter), Co-THT (THT means triphenylene hexathiol; the same applies hereinafter), and Co3(THT)2H3. When the metal element M is Ni, examples include Ni-BHT (BHT means benzene hexathiol; the same applies hereinafter), Ni3(BTC)2 (BTC means benzene tricarboxylate; the same applies hereinafter), and Ni-THT (triphenylene hexathiol). When the metal element M is Fe, examples include Fe-MIL-88A (MIL stands for Metalial Sofistitute Lavoisier frameworks; the same applies below), Fe3O(FA)3-(H2O)2(NO3) (FA stands for fumaric acid), MIL-100, and Benzene-1,3,5-tricarboxylate; iron (3+); hydrate. When the metal element M is Cu, examples include Cu-BHT, Cu3(BHT)2, and CuBDC (BDC stands for 1,4-benzenedicarboxylate; the same applies below). When the metal element M is Mn, examples include Mn-BTC. When the metal element M is Mo, examples include Mo-BTC.

[0019] Among these, the metal organic framework more preferably contains Co, and ZIF-67 is particularly preferred. In this case, the VOC removal catalyst obtained by the production method of the present invention has particularly excellent VOC removal efficiency.

[0020] The method for producing the metal organic framework is not particularly limited, and for example, a wide variety of known methods can be adopted. Specifically, the metal organic framework can be synthesized by reacting a metal source with an organic ligand.

[0021] The metal source is a metal element M alone, a compound of the metal element M, or a mixture thereof. The type of compound of the metal element M is not particularly limited, and examples thereof include inorganic compounds, chlorides, and organic compounds of the metal element M. Examples of inorganic compounds of the metal element M include oxides of the metal element M, compounds containing oxoanions of the metal element M (metallates), nitrates, sulfates, chlorides, chlorates, perchlorates, chloride complexes, carbonates, hydrogencarbonates, phosphates, and hydrogenphosphates of the metal element M, and among these, the inorganic compound of the metal element M is preferably a nitrate. Examples of organic compounds of the metal element M include acetates, oxalates, formates, and succinates.

[0022] The type of organic ligand is not particularly limited, and a wide variety of organic ligands that can be coordinated to transition metals can be used, including, for example, aromatic carboxylic acid compounds, imidazole compounds, and amino compounds that are known to function as ligands.

[0023] Specific organic ligands include p-benzenedicarboxylic acid (H2BDC), o-benzenedicarboxylic acid, m-benzenedicarboxylic acid, 2,5-dihydroxyterephthalic acid (H4DOBDC), 1,3,5-benzenetricarboxylic acid (H3BTC), 1,4-benzenedicarboxylate, 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (H3TATB), 2-aminoterephthalic acid (NH2BDC), 2-methylimidazole (2-MIM), 1- Examples include methylimidazole (1-MIM), 1,4-bis(imidazol-1-yl)benzene (1,4-BIB), 4-(imidazol-1-yl)phthalic acid (H2IPC), 4,4'-dimethyl-2,2'-bipyridyl, 4,4'-oxybisbenzoic acid, fumaric acid, oxalic acid, succinic acid, biphenyl-3,4',5-tricarboxylic acid (BPTC), 4,4'-biphenyldicarboxylate (BPDC), and 2,5-dioxide terephthalate (DOT).

[0024] A solvent can be used in the reaction of the metal source and the organic ligand, and examples of such solvents include water and alcoholic solvents such as ethanol and isopropanol.

[0025] In the reaction of the metal source and the organic ligand, the ratio of the metal source to the organic ligand is not particularly limited, and can be the same as that in known methods for producing metal organic frameworks. For example, the reaction can be carried out by mixing a solution having a metal source concentration of 0.01 to 10 M (preferably 0.05 to 5 M, more preferably 0.1 to 3 M) and a solution having an organic ligand concentration of 0.1 to 20 M (preferably 0.2 to 15 M, more preferably 0.5 to 10 M).

[0026] In the reaction of the metal source and the organic ligand, an ammonium salt such as cetyltrimethylammonium bromide can be used as needed. Such an ammonium salt can be used, for example, in a 0.001 to 1 M solution.

[0027] The reaction temperature of the metal source and the organic ligand is 10 to 50°C, preferably 15 to 35°C, and the mixing time is appropriately selected depending on the temperature.

[0028] The reaction of the metal source and the organic ligand provides a metal-organic framework (MOF), for example, as a solid, which can be separated and washed by an appropriate method.

[0029] In step 1, when the oxidizing agent and the metal organic framework are mixed to generate a precursor, a solvent can be used as needed.

[0030] That is, in step 1, the oxidizing agent and the metal organic framework can be mixed in a solvent. For example, water can be used as the solvent, and other lower alcohols such as methanol and ethanol can also be used. The solvent may be a mixed solvent of water and a lower alcohol, and is preferably water.

[0031] When a solvent is used, for example, the metal-organic framework and the oxidizing agent may be added in a solid state to the solvent. Alternatively, the oxidizing agent and the metal-organic framework may be mixed by adding one solution to the other in a solid state or solution state. Preferably, the metal-organic framework solution and the oxidizing agent solution are mixed together.

[0032] When a solvent is used in mixing the oxidizing agent and the metal-organic framework, the amount of the solvent used is not particularly limited. For example, it is preferable to use the solvent so that the concentration of the metal-organic framework becomes 0.1 to 10 g / L, preferably 0.5 to 5 g / L.

[0033] In the mixing of step 1, it is preferable to mix a solution of the metal-organic framework having a concentration of 0.1 to 10 g / L with a solution of the oxidizing agent having a concentration of 0.1 to 20 g / L. In this case, the solution concentration of the metal-organic framework is more preferably 0.5 to 5 g / L, and the solution concentration of the oxidizing agent is more preferably 0.5 to 16 g / L, and even more preferably 1 to 13 g / L. If necessary, each solution can be ultrasonically treated before mixing.

[0034] In step 1, the temperature when the oxidizing agent and the metal organic framework are mixed is not particularly limited and is, for example, 10 to 50°C, preferably 15 to 35°C, and the mixing time is appropriately selected depending on the temperature.

[0035] In step 1, the precursor produced by mixing the oxidizing agent and the metal organic framework can be separated by an appropriate method such as filtration, centrifugation, etc. Thereafter, it may be washed with a solvent as necessary.

[0036] The precursor produced in step 1 is an oxide containing Mn and metal elements. The precursor obtained in step 1 is subjected to the subsequent calcination treatment in step 2.

[0037] (Process 2) Step 2 is a step for calcining the precursor obtained in Step 1. By such calcination, impurities contained in the precursor obtained in Step 1, i.e., the metal oxide containing Mn, can be removed, and a high-purity oxide can be obtained.

[0038] In step 2, the calcination method is not particularly limited, and a wide variety of known calcination methods can be used. For example, the calcination temperature can be 200°C or higher. In addition, the calcination temperature is preferably 600°C or lower, since the crystallinity of the resulting metal oxide tends to be low. The calcination temperature is preferably 250 to 480°C, more preferably 290 to 450°C, and even more preferably 300 to 400°C.

[0039] The firing time may be appropriately selected depending on the firing temperature, and may be, for example, 1.5 to 5 hours. In step 2, the rate of temperature increase during firing is not particularly limited and may be appropriately set, for example, at 1 to 10°C / min.

[0040] The calcination treatment may be carried out in air or in an inert gas atmosphere. Preferably, the calcination treatment is carried out in air. For the calcination treatment, a known heating device such as a commercially available heating furnace can be used.

[0041] The metal oxide obtained by the calcination treatment in step 2 can be used as the desired VOC removal catalyst.

[0042] The VOC removal catalyst obtained by the production method including the above steps 1 and 2 contains a metal oxide containing Mn, and therefore can efficiently remove VOCs even at low temperatures. When the metal element M is other than Mn, the metal oxide becomes a composite oxide containing a different metal. Note that when the metal element M is Mn, although it appears to be an oxide of Mn, for example, Mn with a different valence may be present in the oxide.

[0043] While metal oxides synthesized from metal-organic frameworks have traditionally been used in VOC removal catalysts, the present invention is characterized by treating the metal-organic framework with the oxidizing agent, i.e., etching, making it possible to produce a catalyst using only low-toxicity raw materials. While not necessarily intended to be limiting, it is believed that the production method of the present invention, which includes an etching treatment, results in the formation of a composite oxide in which manganese and a metal element M (e.g., cobalt) are uniformly dispersed. As a result, the metal oxide has a high specific surface area and low crystallinity, resulting in an increase in so-called structural defects. As a result, many oxygen vacancies and active species are provided, resulting in a large BET specific surface area, and it is presumed that the VOC removal catalyst can efficiently remove VOCs even at low temperatures.

[0044] In the Mn-containing metal oxide produced by the production method of the present invention (specifically, the metal oxide produced in step 2), the content of Mn element is not particularly limited. For example, the Mn-containing metal oxide preferably contains 1 to 35 mol % of Mn element. In this case, the VOC removal catalyst is likely to have an increased VOC removal efficiency.

[0045] Furthermore, when the Mn-containing metal oxide contains a metal element M other than Mn, the composite oxide preferably contains 5 to 40 mol % of the metal element M. In this case, the VOC removal catalyst is likely to have an increased VOC removal efficiency. The composite oxide more preferably contains 6 mol % or more of the metal element M, even more preferably 7 mol % or more, and particularly preferably 8 mol % or more, and more preferably 35 mol % or less, and even more preferably 30 mol % or less.

[0046] 2.VOC removal catalyst The VOC removal catalyst of the present invention contains a metal oxide containing at least Mn, and the metal oxide contains 1 to 35 mol % of Mn element, and the BET specific surface area of ​​the metal oxide is 50 to 500 m 2 / g Such a VOC removal catalyst can be produced, for example, by the production method of the present invention comprising the above-mentioned steps 1 and 2.

[0047] In the VOC removal catalyst of the present invention, the metal oxide is preferably a composite oxide further containing a metal element M (excluding Mn). In this case, the metal element M is at least one selected from the group consisting of transition metals and rare earth elements, and particularly at least one selected from the group consisting of Ce, La, Sm, Fe, Co, Ni, Cu, and Ho, and more preferably at least one selected from the group consisting of Co, Ni, and Cu, with Co being particularly preferred.

[0048] The BET specific surface area of ​​the metal oxide is 80 m 2 / g or more is preferable, and 90m 2 / g or more is more preferable, and 95m 2 / g or more is more preferable, and 100m 2 It is particularly preferable that the saturation coefficient is 1 / g or more.

[0049] When the VOC removal catalyst of the present invention contains the composite oxide, it preferably contains 5 to 40 mol % of the metal element M. In this case, the VOC removal catalyst tends to have an increased VOC removal efficiency.

[0050] The composite oxide preferably contains 6 mol% or more, and more preferably 38 mol% or less, of the Mn element. The composite oxide preferably contains 10 mol% or more, more preferably 15 mol% or more, and particularly preferably 18 mol% or more, of the metal element M, and more preferably 35 mol% or less, and even more preferably 30 mol% or less.

[0051] In the composite oxide, the content of the metal element M is preferably 3 mol% or more, more preferably 5.5 mol% or more, and even more preferably 6 mol% or more, and is preferably 40 mol% or less, more preferably 30 mol% or less, even more preferably 20 mol% or less, and particularly preferably 10 mol% or less.

[0052] The composite oxide contains oxygen in addition to Mn element and metal element M. The oxygen content of the composite oxide is, for example, 50 mol % or more and 70 mol % or less. In addition to Mn element, metal element M, and oxygen, the composite oxide may contain, for example, a metal element (e.g., a metal element such as potassium) derived from the oxidizing agent used during synthesis.

[0053] The VOC removal catalyst of the present invention can be formed solely from the metal oxide or the composite oxide, or can contain components other than the metal oxide or the composite oxide, as long as the effects of the present invention are not impaired.

[0054] The metal oxide contained in the VOC removal catalyst of the present invention is, for example, in the form of a powder. The shape of the metal oxide is not particularly limited, and it can be formed into various shapes such as particles, polygons, scales, fibers, and rods, among which nanoparticles are preferred.

[0055] The metal oxide contained in the VOC removal catalyst of the present invention may be crystalline or amorphous, with amorphous being preferred in that catalytic performance is more likely to be improved.

[0056] When the metal oxide is a composite oxide, the lower the content of a single oxide of metal element M (e.g., Co3O4) in the composite oxide, the better. In this case, the VOC removal catalyst can have particularly excellent VOC removal efficiency even at low temperatures. In the composite oxide, the content of a single oxide of metal element M (e.g., Co3O4) is preferably 50 mass% or less, more preferably 35 mass% or less, even more preferably 20 mass% or less, and particularly preferably 10 mass% or less.

[0057] 3.VOC removal method The VOC removal method of the present invention comprises a step of burning VOCs using the above-mentioned VOC removal catalyst or a VOC catalyst obtained by a production method comprising the steps 1 and 2.

[0058] For example, a VOC removal catalyst is placed in a container, and VOCs such as toluene are introduced into the container and treated at a predetermined temperature to combust the VOCs. This allows the VOCs to be removed. If necessary, nitrogen and / or oxygen can be introduced into the container, allowing the VOCs to be combusted in the presence of either or both of nitrogen and oxygen.

[0059] The type of container used for VOC removal is not particularly limited, and for example, a wide variety of known containers used in catalytic combustion of VOCs can be used. The treatment temperature for VOCs in the container is not particularly limited, and can be the same as the treatment temperature set for known VOC removal. In particular, the present invention achieves excellent VOC removal efficiency even at low temperatures by using the above-mentioned VOC removal catalyst. [Example]

[0060] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0061] (Production Example 1) An aqueous solution (A) containing 11.2 g of 2-methylimidazole and an aqueous solution (B) containing 1791 mg of cobalt nitrate and 20 mg of cetyltrimethylammonium bromide were prepared. Aqueous solutions (A) and (B) were mixed and stirred at room temperature (25°C) for 12 hours. The resulting solid was washed with water and alcohol several times and then centrifuged to recover the solid. The solid was then dried at 60°C for 12 hours and then at 110°C for 24 hours to obtain a metal-organic framework (referred to as Co-MOF). The resulting Co-MOF was confirmed to be ZIF-67.

[0062] Example 1 400 mg of the Co-MOF obtained in Preparation Example 1 was weighed and dispersed in 100 mL of deionized water. This was followed by ultrasonic treatment for 30 minutes to prepare Dispersion C. 100 mL of KMnO4 solution (concentration: 1 g / L) was added to Dispersion C as an oxidant and stirred for 1 hour. The solid precipitate was then washed several times with water and alcohol, recovered by centrifugation, and then dried at 60 °C for 24 hours to obtain a precursor (Step 1). This precursor was calcined at 350 °C for 3 hours to obtain a metal oxide powder. This metal oxide was used as a VOC removal catalyst and designated "MnCoxOy-1."

[0063] Example 2 A metal oxide powder was obtained in the same manner as in Example 1, except that the concentration of the KMnO4 solution was changed to 6 g / L. This metal oxide was used as a VOC removal catalyst and was designated "MnCoxOy-6."

[0064] Example 3 A metal oxide powder was obtained in the same manner as in Example 1, except that the concentration of the KMnO4 solution was changed to 11 g / L. This metal oxide was used as a VOC removal catalyst and was designated "MnCoxOy-11."

[0065] (Comparative Example 1) An aqueous solution (A) containing 11.2 g of 2-methylimidazole and an aqueous solution (B) containing 1791 mg of cobalt nitrate and 20 mg of cetyltrimethylammonium bromide were prepared. Aqueous solutions (A) and (B) were mixed and stirred at room temperature (25°C) for 12 hours. The resulting solid was then washed with water and alcohol several times and centrifuged to recover the solid. The solid was then dried at 60°C for 12 hours and then at 110°C for 24 hours. It was then calcined in an air atmosphere at 350°C for 3 hours to obtain Co oxide (CoO). x ) was obtained.

[0066] (Comparative Example 2) An aqueous solution (A) containing 400 mg of 2-methylimidazole and an aqueous solution (B) containing 1100 mg of KMnO4 were mixed and stirred at room temperature (25°C) for 12 hours. The resulting solid was washed with water and alcohol several times and then centrifuged to recover the solid. The solid was dried at 60°C for 12 hours and then calcined at 350°C for 3 hours in an air atmosphere to obtain Mn oxide (MnO x ) was obtained.

[0067] (Comparative Example 3) Manganese cobalt oxide (MOF-MnCo) was synthesized as described in Journal of Hazardous Materials, 349 (2018) 119-127. 1.5 g of polyvinylpyrrolidone, 0.22 g of Mn(CH3COO)2·4H2O, 30 mL of deionized water, and 60 mL of ethanol were mixed under magnetic stirring. 60 mL of K3Co(CN)6 (Mn:Co molar ratio 1:1) aqueous solution was added dropwise to the mixture. The mixture was then aged at room temperature for 24 hours to obtain a precipitate. The resulting precipitate was collected, washed with deionized water and ethanol, frozen at -46 °C for 12 hours, and then dried in an oven at 60 °C for 6 hours. The mixture was then sintered in air at 450 °C (heating rate 1 °C / min) for 2 hours to obtain a manganese and cobalt oxide (MOF-MnCo).

[0068] <Evaluation method> (VOC removal test) A toluene removal test was conducted using the VOC removal catalyst obtained in each example according to the schematic flow shown in Figure 1. In this test, a container was filled with the VOC removal catalyst (Catalyst in the figure) sandwiched between quartz wool, and toluene was introduced into the container at a predetermined flow rate to cause a reaction, thereby removing the toluene. As shown in Figure 1, the container was connected to an oxygen cylinder and a nitrogen cylinder, allowing oxygen and nitrogen to flow into the container. The conditions for the toluene removal test were as follows: a glass reactor with an inner diameter of 8 mm was used, and the amount of VOC removal catalyst packed therein was 50 mg, and the toluene concentration in the container was set to 1,000 ppm by volume. In addition, the flow rate of nitrogen gas used as a carrier into the container was set to 35 cm 3 / min, and the nitrogen gas flow rate for toluene introduction was 5cm 3 / min, oxygen gas flow rate 10cm 3 The reaction temperature in the vessel was adjusted to various temperatures between 130 and 300°C, and the toluene removal characteristics were evaluated. In the range of 130 to 200°C, three samples were taken every 10°C, in the range of 200 to 250°C, three samples were taken every 5°C, and in the range of 260 to 300°C, three samples were taken every 10°C. VOC concentrations were measured using a Shimadzu GC-2014 gas chromatograph. The carbon dioxide concentration emitted from the vessel outlet was measured using a HORIBA FG-120 FT-IR gas analyzer.

[0069] Figure 2 shows SEM images of the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 and 2. Comparative Example 1 had a three-dimensional polygonal shape, and Comparative Example 2 showed no distinctive shape, whereas the catalyst of Example 1 was observed to have an irregular flake shape, and as the amount of KMnO4 added increased, a change in shape to irregular nanoparticles was observed (Examples 2 and 3).

[0070] Table 1 shows the results of elemental analysis of the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 3 by EDS analysis.

[0071] [Table 1]

[0072] Table 2 shows the results of measuring the BET specific surface area of ​​the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 3. The catalysts (metal oxides) obtained in the examples had high BET specific surface areas.

[0073] [Table 2]

[0074] Figure 3 shows the XRD spectra of the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 and 2. In the XRD spectra, Comparative Example 1 (CoOx) exhibited a sharp diffraction peak of the Co3O4 phase, while Comparative Example 2 (MnOx) was found to be a multiphase mixture containing MnO2, Mn3O4, and K2Mn4O8 phases. On the other hand, Examples MnCoxOy-11 and MnCoxOy-6 exhibited weak, characteristic diffraction peaks of the MnO2 and Co3O4 phases, and the Co3O4 peak intensity decreased with increasing KMnO4 content. The catalysts of the Examples contained 35% or less Co3O4 by mass, which may be the reason for their excellent VOC removal performance.

[0075] FIG. 4 shows the results of the VOC removal test using the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 3. Specifically, FIG. 4 is a plot showing the relationship between temperature (X axis) and toluene removal rate (Y axis). The graph in FIG. 4 also shows the 50% decomposition temperature (T 50% ), 90% decomposition temperature (T 90% ), 100% decomposition temperature (T 100% ) value.

[0076] Table 3 summarizes the results of FIG. 4 and shows the results of VOC removal tests using the catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 3. The results of FIG. 4 and Table 3 show that the VOC removal catalysts obtained in each Example have better VOC removal performance than the Comparative Examples. Therefore, it was found that the VOC removal catalysts obtained in each Example can be suitably used as catalysts for the catalytic combustion of toluene, a typical VOC substance. In particular, it was found that this depends on the amount of potassium permanganate used in producing the catalyst.

[0077] [Table 3]

Claims

1. A method for producing a VOC removal catalyst, comprising: Step 1: Mixing an oxidizing agent containing Mn with a metal organic framework containing Co to obtain a precursor; and Step 2: calcining the precursor obtained in step 1 to obtain a composite oxide containing Mn and Co; A method for producing a VOC removal catalyst comprising:

2. The method according to claim 1, wherein the composite oxide contains 1 to 35 mol % of Mn element.

3. A method for removing VOCs, comprising a step of decomposing VOCs using the VOC removal catalyst obtained by the production method according to claim 1 or 2.

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