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

Abstract

To provide a VOC removal catalyst that can be easily produced, has high VOC removal efficiency, and can efficiently remove VOC even at low temperatures and also provide a method for producing the same and a VOC removal method.SOLUTION: The inventive VOC removal catalyst contains crystalline manganese oxide containing metal M, the metal M including at least one selected from the group consisting of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. A method for producing the inventive VOC removal catalyst includes a step 1 for mixing a source liquid A containing a manganese source, a source liquid B containing a metal element M source, and a source liquid C containing a reductant, to obtain a product, and a step 2 for firing the product obtained in the step 1, the metal element M including at least one selected from the group consisting of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.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. [Background technology]

[0002] VOC is an abbreviation for volatile organic compounds, and known examples include toluene, xylene, benzene, ethyl acetate, methanol, and dichloromethane. Although such VOCs are widely used in solvents, adhesives, chemical raw materials, etc., VOCs are pointed out as causing 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 demand for the establishment of technology to more efficiently remove VOCs in order to further reduce VOC emissions.

[0003] A method using catalytic oxidation is known as a technique for removing VOCs. This method is considered to be the most promising because it removes VOCs at a relatively low temperature. Since catalytic oxidation mainly uses transition metal oxides, it is advantageous in terms of cost compared to precious 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] JP 2019-147131 A 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 they also have the problem of taking time to manufacture, so overall there are still challenges to be overcome when considering practical application. From these perspectives, there is currently a demand for the development of a catalyst that can be easily manufactured and can efficiently remove VOCs even at low temperatures.

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

[0007] As a result of intensive research into achieving the above object, the inventors have discovered that the above object can be achieved by utilizing crystalline manganese oxide containing a specific metal, 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 VOC removal catalyst comprising: A crystalline manganese oxide containing a metal M, The VOC removal catalyst, wherein the metal M includes at least one selected from the group consisting of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Section 2 Item 2. The VOC removal catalyst according to item 1, wherein the crystalline manganese oxide containing the metal M is a crystalline manganese oxide containing an oxide of Ce. Section 3 Item 2. The VOC removal catalyst according to item 1, wherein in the crystalline manganese oxide containing metal M, a molar ratio of metal M to manganese (metal M:Mn) is 1:0.001 to 1:5. Section 4 Item 3. The VOC removal catalyst according to item 2, wherein in the crystalline manganese oxide containing an oxide of Ce, a molar ratio of cerium to manganese (Ce:Mn) is 1:0.001 to 1:5. Section 5 A step 1 of obtaining a product by mixing a raw material liquid A containing a manganese source, a raw material liquid B containing a metal element M source, and a raw material liquid C containing a reducing agent; Step 2 of calcining the product obtained in step 1; Equipped with A method for producing a VOC removal catalyst, wherein the metal element M includes at least one selected from the group consisting of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Section 6 Item 6. The method for producing a VOC removal catalyst according to Item 5, wherein the reducing agent is a carboxylic acid compound and / or vitamin C. Section 7 Item 7. The method for producing a VOC removal catalyst according to Item 6, wherein the carboxylic acid compound is at least one selected from the group consisting of citric acid, formic acid, and acetic acid. Section 8 Item 8. A method for removing VOCs, comprising a step of decomposing VOCs using the VOC removal catalyst according to any one of Items 1 to 4 or the VOC catalyst obtained by the production method according to any one of Items 5 to 7. Effect 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. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a method for producing a VOC removal catalyst of the present invention. [Diagram 2] FIG. 1 is a schematic diagram showing a flow of an evaluation test method for a VOC removal catalyst. [Diagram 3] 1 shows SEM images of the catalysts obtained in Examples 1 to 4 and Comparative Example 1. [Figure 4]1 shows XRD spectra of the catalysts obtained in Examples 1 to 4 and Comparative Example 1. [Diagram 5] The results of VOC removal tests using the catalysts obtained in the examples and comparative examples are shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expressions "containing" and "comprise" include the concepts of "containing", "comprises", "consists essentially of" and "consists only of".

[0012] 1.VOC removal catalyst The VOC removal catalyst of the present invention comprises a crystalline manganese oxide containing a metal M, and the metal M comprises at least one selected from the group consisting of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

[0013] The VOC removal catalyst of the present invention has the property of decomposing VOCs by oxidation or the like. In particular, the VOC removal catalyst of the present invention is easy to manufacture, has excellent VOC removal efficiency, and can efficiently remove VOCs even at low temperatures. Specific embodiments of the VOC removal catalyst of the present invention will be described below.

[0014] The crystalline manganese oxide containing metal M contained in the VOC removal catalyst of the present invention is a main component of the VOC removal catalyst of the present invention. Hereinafter, the "crystalline manganese oxide containing metal M" may be referred to as "manganese oxide 1."

[0015] An example of manganese oxide 1 is crystalline manganese oxide containing an oxide of metal M. More specifically, manganese oxide 1 may be a mixture of an oxide of metal M and crystalline manganese oxide, or a mixture of an oxide of metal M and crystalline manganese oxide. Alternatively, manganese oxide 1 may be a solid solution.

[0016] The presence of metal M in manganese oxide 1 reduces the crystallinity of crystalline manganese oxide. As a result, the VOC removal catalyst of the present invention has excellent VOC removal efficiency, and can efficiently remove VOCs even when VOCs are decomposed at low temperatures.

[0017] The metal M contained in the manganese oxide 1 may be one type alone or two or more types.

[0018] The metal M is preferably Ce. In this case, the crystallinity of the crystalline manganese oxide in the manganese oxide 1 is smaller, so that the VOC removal catalyst of the present invention has excellent VOC removal efficiency and can efficiently remove VOCs even when the VOCs are decomposed at a lower temperature. Among them, the metal M is preferably trivalent Ce. 3+ This is particularly preferable, and the catalytic performance of the VOC removal catalyst is further improved.

[0019] Therefore, in the VOC removal catalyst of the present invention, manganese oxide 1 is preferably a crystalline manganese oxide containing an oxide of Ce.

[0020] In manganese oxide 1, the molar ratio of metal M to manganese (metal M:Mn) is preferably 1:0.001 to 1:5. In this case, the VOC removal catalyst of the present invention has excellent VOC removal efficiency and is likely to have improved VOC decomposition performance at low temperatures. Metal M:Mn is more preferably 1:0.1 to 1:4.5, further preferably 1:1 to 1:4, and particularly preferably 1:3 to 1:4.

[0021] When manganese oxide 1 is a crystalline manganese oxide containing an oxide of Ce, the molar ratio of cerium to manganese (Ce:Mn) is preferably 1:0.001 to 1:5. In this case, the VOC removal catalyst of the present invention has excellent VOC removal efficiency and is more likely to have improved VOC decomposition performance at low temperatures. Ce:Mn is more preferably 1:0.1 to 1:4.5, even more preferably 1:1 to 1:4, and particularly preferably 1:3 to 1:4.

[0022] When the manganese oxide 1 contains a large proportion of manganese, it is more likely to form a solid solution, and as a result, the VOC removal catalyst of the present invention has even better VOC removal efficiency and can remove VOCs particularly efficiently at low temperatures. This tendency is particularly pronounced when the metal M is Ce, that is, when the manganese oxide 1 is a crystalline manganese oxide containing an oxide of Ce. When the metal M:Mn or Ce:Mn is 1:3 to 1:4, the VOC removal catalyst has particularly excellent VOC decomposition properties at low temperatures.

[0023] In the VOC removal catalyst of the present invention, the metal M may be present in the crystalline manganese oxide, or the metal M may be present not inside the manganese oxide, or may be present on the surface as well as inside. For example, the metal M may be present in the crystal structure of the crystalline manganese oxide. This reduces the crystallinity of the crystalline manganese oxide, resulting in excellent VOC decomposition properties at low temperatures for the VOC removal catalyst.

[0024] In manganese oxide 1, manganese is Mn 2+ , Mn 3+ , and Mn 4+ These may coexist in two or more forms. Mn is the most effective VOC catalyst for decomposition at low temperatures. 3+ It is preferable that a large amount of Mn is present on the surface of the VOC catalyst. 3+ It is more preferable that a large amount of is present, in which case the VOC removal efficiency is excellent and the VOC decomposition property at low temperatures is further excellent.

[0025] As described above, manganese present in manganese oxide 1 can have various valences. For example, in the case of crystalline manganese oxide containing Ce, the following general formula (1) CeMn x O y (1) It can be expressed as:

[0026] Here, x is 0.5≦x≦5, preferably 1≦x≦4, more preferably 2≦x≦4, and particularly preferably 3≦x≦4. Also, y is 2.5≦y≦18. y is preferably 3 or more, more preferably 3.5 or more, and particularly preferably 4 or more. Also, y is preferably 17 or less, further preferably 16 or less, and particularly preferably 15 or less.

[0027] In the VOC removal catalyst of the present invention, the structure of manganese oxide 1 can be analyzed from an XRD spectrum, and the crystallinity of manganese oxide can be relatively known from the spectrum.

[0028] The shape of the manganese oxide 1 is not particularly limited, and it can take various shapes such as particles, rods, needles, fibers, scales, etc. It is also preferable that the manganese oxide 1 is porous, in which case the VOC decomposition properties at low temperatures are likely to be improved.

[0029] As described above, the crystalline manganese oxide containing the metal M has a low degree of crystallinity, i.e., low crystallinity. Therefore, the VOC catalyst of the present invention has excellent VOC removal efficiency, can efficiently decompose VOCs even when VOCs are treated at low temperatures, and has excellent catalytic performance.

[0030] The VOC removal catalyst of the present invention may contain other components (e.g., other elements, compounds, additives, etc.) other than manganese oxide 1, so long as the effects of the present invention are not impaired. The VOC catalyst of the present invention may be formed only from manganese oxide 1. In this case, it is permitted to contain unavoidable elements, components, etc. that may be contained in the VOC catalyst. When the VOC catalyst of the present invention contains other elements or components other than manganese oxide 1, the total content thereof may be, for example, 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less or 0.5% by mass, based on the total mass of the VOC catalyst.

[0031] The method for producing the VOC removal catalyst of the present invention is not particularly limited, and the catalyst can be produced by, for example, various known methods. Specifically, the VOC removal catalyst of the present invention can be produced by a production method including steps 1 and 2 described below.

[0032] 2. Manufacturing method of VOC removal catalyst The method for producing a VOC removal catalyst of the present invention includes the following steps 1 and 2. Step 1: A step of obtaining a product by mixing raw material liquid A containing a manganese source, raw material liquid B containing a source of metal element M, and raw material liquid C containing a reducing agent. Step 2: Calcining the product obtained in step 1.

[0033] In the source of metal element M used in step 1, the metal element M includes at least one selected from the group consisting of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0034] (Process 1) In step 1, a mixing treatment is carried out among raw material liquid A containing a manganese source, raw material liquid B containing a source of metal element M, and raw material liquid C containing a reducing agent.

[0035] The manganese source is dissolved or dispersed in a solvent in the manganese source-containing raw material liquid A used in step 1. The manganese source may be manganese itself or a compound containing manganese, but is preferably a compound containing manganese.

[0036] The type of the compound containing manganese is not particularly limited, and may be, for example, various inorganic compounds containing manganese. Examples of the inorganic compound containing manganese include permanganate, nitrate, sulfate, chloride, hydrochloride, chlorate, perchlorate, carbonate, hydrogencarbonate, phosphate, and hydrogenphosphate of manganese, and among them, the inorganic compound containing manganese is preferably permanganate. A specific example of the permanganate is potassium permanganate (KMnO4).

[0037] Other examples of the manganese-containing compound include various organic compounds containing manganese, such as manganese acetate, oxalate, formate, and succinate.

[0038] Additionally, the manganese-containing compound may contain two or more different anions (eg, ammonium manganese sulfate, etc.).

[0039] It is particularly preferable to use potassium permanganate (KMnO4) as the manganese source because the VOC catalyst can be easily produced.

[0040] The raw material liquid B containing the metal element M source used in step 1 has the metal element M source dissolved or dispersed in a solvent. The metal element M source may be the metal element M alone or a compound containing the metal element M. The metal element M is preferably Ce. In this case, the obtained VOC catalyst can efficiently remove VOCs.

[0041] The type of compound containing the metal element M is not particularly limited, and examples thereof include various inorganic compounds containing the metal element M. Examples of inorganic compounds containing the metal element M include nitrates, sulfates, oxides, chlorides, hydrochlorides, chlorates, perchlorates, carbonates, hydrogencarbonates, phosphates, and hydrogenphosphates of the metal element M.

[0042] Furthermore, examples of the compound containing the metal element M include various organic compounds, such as acetates, oxalates, formates, and succinates of the metal element M, and cyclodipentadienyl dichloride salts.

[0043] In view of ease of production of the VOC catalyst, the source of the metal element M is preferably an inorganic compound containing the metal element M, and in view of excellent reactivity, it is more preferable to use a nitrate of the metal element M, and among these, cerium nitrate (Ce(NO3)3) is particularly preferable.

[0044] In the raw material liquid C containing a reducing agent used in step 1, the reducing agent is dissolved or dispersed in a solvent.

[0045] The type of reducing agent is not particularly limited, and for example, a wide variety of known reducing agents can be used. Specifically, the reducing agent can be a carboxylic acid compound and / or vitamin C. The carboxylic acid compound can be various compounds having a reducing action, for example, at least one selected from the group consisting of citric acid, formic acid, and acetic acid. The reducing agent is preferably citric acid, since it has excellent VOC removal efficiency at low temperatures and is easy to exert an etching effect on the catalyst surface.

[0046] The reducing agent can be used alone or in combination of two or more kinds.

[0047] The raw material liquid A, the raw material liquid B, and the raw material liquid C may each contain a solvent. The type of the solvent is not particularly limited, and for example, water; alcohols having 1 to 4 carbon atoms such as methanol and ethanol; and mixed solvents thereof; amide-based solvents such as N,N-dimethylformamide; pyrrolidone-based solvents such as N-methylpyrrolidone, etc. can be used. In terms of facilitating the reaction in step 1, the solvents contained in the raw material liquid A, the raw material liquid B, and the raw material liquid C are preferably water and the alcohol, or mixed solvents thereof, and more preferably water. The solvents contained in the raw material liquid A, the raw material liquid B, and the raw material liquid C may be the same as each other, or may be partially or entirely different, and more preferably all of them are water.

[0048] In the raw material solution A, the concentration of the manganese source is not particularly limited. For example, the concentration of manganese in the raw material solution A is 1×10 -4 ~2M, preferably 1×10 -3 ~1M, more preferably 1×10 -2 It can be ~0.5M.

[0049] In the raw material solution B, the concentration of the metal element M source is not particularly limited. For example, the concentration of the metal element M source in the raw material solution B is 1×10-4 ~2M, preferably 1×10 -3 ~1M, more preferably 1×10 -2 It can be ~0.5M.

[0050] The concentration of the reducing agent in the raw material solution C is not particularly limited. For example, the concentration of the reducing agent in the raw material solution C is 1×10 -4 ~2M, preferably 1×10 -3 ~1M, more preferably 1×10 -2 It can be ~0.5M.

[0051] In step 1, the mixing ratio of raw material liquid A and raw material liquid B is not particularly limited. For example, it is preferable to mix the two so that the molar ratio of metal element M to manganese (metal element M:Mn) is 1:0.5 to 1:5. In this case, the obtained VOC removal catalyst is likely to have improved VOC decomposition performance at low temperatures. The metal element M:Mn is more preferably 1:1 to 1:4, further preferably 1:2 to 1:4, and particularly preferably 1:3 to 1:4.

[0052] There is no particular limitation on the amount of raw material liquid C used in step 1. For example, the amount of raw material liquid C can be adjusted so that the molar ratio of the reducing agent to manganese (reducing agent:manganese) in raw material liquid C is 1:0.1 to 1:5.

[0053] In step 1, the method of mixing raw material liquid A, raw material liquid B, and raw material liquid C is not particularly limited. As an example, the mixing process can be performed by adding raw material liquid A and raw material liquid B to raw material liquid C that is being stirred. In this case, raw material liquid A and raw material liquid B can be added separately to raw material liquid C, or raw material liquid A and raw material liquid B can be mixed in advance and then added to raw material liquid C. When raw material liquid A and raw material liquid B are added separately to raw material liquid C, raw material liquid A and raw material liquid B can also be added to raw material liquid C at the same time.

[0054] The rate at which raw material liquid A and raw material liquid B are added to raw material liquid C is not particularly limited, and they can be supplied in the range of, for example, 0.1 to 50 mL / min.

[0055] In the mixing process of raw material liquid A, raw material liquid B, and raw material liquid C, the temperature during mixing is not particularly limited and can be, for example, 5 to 40° C., and preferably around room temperature (for example, 15 to 30° C.). The time for the mixing process is also not particularly limited and can be set appropriately depending on the temperature during mixing.

[0056] By mixing raw material liquid A, raw material liquid B, and raw material liquid C, the manganese source, the metal element M source, and the reducing agent react with each other, and a precipitate may be generated. The resulting precipitate can be separated by an appropriate method such as centrifugation or filtration. The separated precipitate can be washed, dried, etc., as necessary.

[0057] The precipitate obtained by the above mixing process is calcined in step 2 described below to become the target VOC removal catalyst. Therefore, the precipitate obtained by the mixing process is, so to speak, a precursor of the VOC removal catalyst. Such a precursor can be, for example, manganese oxide (MnO x The precursor includes oxides of cerium (e.g., CeO2), and may also include solid solutions of the above. The precursor is, for example, represented by the above general formula (1). The precursor also includes the reducing agent used in step 1, but this reducing agent can be removed by calcination in step 2 described below.

[0058] (Process 2) Step 2 is a step for calcining the product (precursor) obtained in step 1. The intended VOC removal catalyst is obtained by such calcination.

[0059] In step 2, the method of calcination is not particularly limited, and a wide variety of known calcination methods can be used. For example, the temperature of the calcination can be 250°C or higher. In addition, the calcination temperature is preferably less than 650°C, since the crystallinity of manganese oxide in the VOC catalyst obtained by calcination 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.

[0060] 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 heating rate during firing is not particularly limited and may be appropriately set, for example, 1 to 10° C. / min.

[0061] The calcination may be carried out in air or in an inert gas atmosphere. It is preferable to carry out the calcination in air. For example, a known heating device such as a commercially available heating furnace can be used for the calcination.

[0062] The calcination treatment in step 2 removes, for example, the remaining reducing agent and forms a sintered body of the product (precursor), which can be obtained as the target VOC removal catalyst. The obtained VOC removal catalyst is a catalyst containing the above-mentioned crystalline manganese oxide containing metal M (manganese oxide 1), for example, crystalline manganese oxide containing Ce.

[0063] According to the production method including the above steps 1 and 2, the VOC removal catalyst of the present invention can be easily obtained through simple steps, and the obtained VOC removal catalyst can efficiently remove VOCs even at low temperatures.

[0064] 3.VOC removal method The VOC removal method of the present invention includes a step of combusting VOCs using the above-mentioned VOC removal catalyst or the VOC catalyst obtained by the production method including the steps 1 and 2.

[0065] 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 makes it possible to remove the VOCs. If necessary, one or both of nitrogen and oxygen can be introduced into the container, and the VOCs can be combusted in the presence of one or both of nitrogen and oxygen.

[0066] The type of container used for removing VOCs is not particularly limited, and for example, known containers used in catalytic combustion of VOCs can be widely used. The treatment temperature of VOCs in the container is not particularly limited, and can be the same as the treatment temperature set for known VOC removal. In particular, in the present invention, by using the above-mentioned VOC removal catalyst, the VOC removal efficiency is excellent even at low temperatures. EXAMPLES

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the embodiments of these examples.

[0068] Example 1 The VOC removal catalyst was synthesized according to the procedure shown in the schematic diagram of FIG. 1. First, an aqueous solution with a concentration of 0.1 M KMnO4 (A solution in FIG. 1) was prepared as raw material solution A, and an aqueous solution with a concentration of 0.1 M Ce(NO3)3 (B solution) was prepared as raw material solution B. These were dropped into a vigorously stirred 0.2 M citric acid aqueous solution (raw material solution C) at a feed rate of 10 mL / min. This resulted in a brown-black suspension. The resulting suspension was centrifuged to separate the solid (product), and the resulting solid was washed several times with deionized water and then dried at 60°C overnight to obtain a precursor of the VOC removal catalyst (step 1). This precursor was heated to 350°C in a muffle furnace under an air atmosphere at a heating rate of 5°C / min, and the product was calcined at this temperature for 3 hours (step 2), to obtain a VOC removal catalyst with Mn:Ce of 1:1.

[0069] Example 2 Steps 1 and 2 were carried out in the same manner as in Example 1, except that the concentration of KMnO4 in raw material solution A was changed to 0.133 M and the concentration of Ce(NO3)3 in raw material solution B was changed to 0.067 M, thereby obtaining a VOC removal catalyst with a Mn:Ce ratio of 2:1.

[0070] Example 3 Steps 1 and 2 were carried out in the same manner as in Example 1, except that the concentration of KMnO4 in raw material solution A was changed to 0.15 M and the concentration of Ce(NO3)3 in raw material solution B was changed to 0.05 M, thereby obtaining a VOC removal catalyst with a Mn:Ce ratio of 3:1.

[0071] Example 4 Steps 1 and 2 were carried out in the same manner as in Example 1, except that the concentration of KMnO4 in raw material solution A was changed to 0.16 M and the concentration of Ce(NO3)3 in raw material solution B was changed to 0.04 M, thereby obtaining a VOC removal catalyst with a Mn:Ce ratio of 4:1.

[0072] Comparative Example 1 An aqueous solution with a KMnO4 concentration of 0.1M was added dropwise at a feed rate of 10 mL / min to a vigorously stirred 0.2M aqueous citric acid solution. This resulted in a brown-black suspension. The resulting suspension was centrifuged to separate the solid (product), which was washed several times with deionized water and then dried overnight at 60°C to obtain a precursor for VOC removal catalyst. This precursor was heated to 350°C in a muffle furnace under an air atmosphere at a heating rate of 5°C / min, and the product was calcined at this temperature for 3 hours (step 2) to obtain a comparative catalyst.

[0073] <Evaluation method> (VOC removal test) A toluene removal test was carried out on the VOC removal catalyst obtained in each Example according to the schematic flow shown in Figure 2. In this test, the VOC removal catalyst was packed in a container so as to be sandwiched between quartz wool, and toluene was flowed into the container at a predetermined flow rate to cause a reaction and remove the toluene. As shown in Figure 2, the container was connected to an oxygen cylinder and a nitrogen cylinder, allowing oxygen and nitrogen to flow into the container. As conditions for the toluene removal test, a glass reactor with an inner diameter of 8 mm was used, the amount of VOC removal catalyst packed therein was 50 mg, and the toluene concentration in the container was set to 1000 ppm by volume. In addition, the flow rate of nitrogen gas carrier into the container was set to 40 cm 3 / min, nitrogen gas flow rate for toluene introduction was 40 mL / min, and oxygen gas flow rate was 10 cm 3 / min. The reaction temperature in the vessel was adjusted to various temperatures in the range of 130-300°C to evaluate the toluene removal characteristics. In the range of 130-210°C, sampling was performed twice every 10°C, and in the range of 210-300°C, sampling was performed twice every 5°C. The VOC concentration was measured using a Shimadzu Corporation "GC-2014 Gas Chromatograph." In addition, the carbon dioxide concentration discharged from the vessel outlet was measured using a HORIBA Corporation "FG-120" FT-IR gas analyzer.

[0074] Fig. 3 shows SEM images of the catalysts obtained in Examples 1 to 4 and Comparative Example 1. Fig. 3 shows that when the molar ratio of Mn is increased as in Example 4, the catalyst is formed in a porous state.

[0075] FIG. 4 shows the XRD spectra of the catalysts obtained in Examples 1 to 4 and Comparative Example 1.

[0076] 4, by comparing the XRD spectrum of Comparative Example 1 with the XRD spectra of Examples 1 to 4, it was found that the inclusion of Ce as the metal M can suppress the crystallinity of manganese oxide (MnOx). In particular, it was found that when the molar ratio of Mn is large as in Examples 3 and 4, the degree of crystallinity is very small, resulting in a structure close to that of amorphous manganese oxide. It is believed that metal elements such as Ce are inserted into the lattice structure of manganese oxide to expand the interlayer spacing, thereby reducing the crystallinity of manganese oxide.

[0077] FIG. 5 shows the results of a VOC removal test using the catalysts obtained in Examples 1 to 4 and Comparative Example 1. Specifically, FIG. 5 is a plot showing the relationship between temperature (X-axis) and toluene removal rate (Y-axis). The graph in FIG. 5 also shows the 10% toluene decomposition temperature (T 10% ), 50% decomposition temperature (T 50% ), 90% decomposition temperature (T 90% ) and 100% decomposition temperature (T 100% ) value is inserted.

[0078] From the results in FIG. 5 and FIG. 6, it can be seen that the VOC removal catalysts obtained in each Example have better VOC removal performance than Comparative Example 1. The catalyst obtained in Comparative Example 1 showed a toluene decomposition rate of less than 70% even at 300°C, whereas the catalysts obtained in each Example showed that 90% or more of toluene was decomposed even when VOCs were treated at a temperature lower than 280°C. In particular, the catalysts obtained in Examples 3 and 4 showed a toluene decomposition rate of 100% (T 100% ) were 215℃ and 245℃, respectively, indicating that the VOC removal efficiency at low temperatures was particularly excellent.

[0079] From the above, it was found that the VOC removal catalysts obtained in the respective Examples can be suitably used as catalysts for the catalytic combustion of toluene, which is a typical VOC substance.

Claims

1. A method for producing a VOC removal catalyst, comprising: A step 1 of obtaining a product by mixing a raw material liquid A containing a manganese source, a raw material liquid B containing a cerium source, and a raw material liquid C containing a reducing agent at 5 to 40° C.; Step 2 of calcining the product obtained in step 1 at 250 to 480° C.; Equipped with The VOC removal catalyst comprises crystalline manganese oxide containing Ce, and the molar ratio of cerium to manganese (Ce:Mn) is 1:1 to 1:

4.

2. The method for producing a VOC removal catalyst according to claim 1, wherein the reducing agent is a carboxylic acid compound and / or vitamin C.

3. The method for producing a VOC removal catalyst according to claim 2, wherein the carboxylic acid compound is at least one selected from the group consisting of citric acid, formic acid, and acetic acid.

4. A method for removing VOCs, comprising a step of decomposing VOCs using a VOC catalyst obtained by the manufacturing method described in any one of claims 1 to 3.

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