KR102205552B1 - Mn-iron oxide based SCR catalyst with enhanced low temperature activity and a method for manufacturing the same - Google Patents

Abstract

The present invention relates to an SCR denitration catalyst in which the surface of a porous support is coated with iron oxide particles doped with manganese, and a method of preparing the same.

Description

Mn-iron oxide based SCR catalyst with enhanced low temperature activity and a method for manufacturing the same}

The present invention relates to an SCR denitration catalyst in which the surface of a porous support is coated with iron oxide particles doped with manganese, and a method of preparing the same.

Nitric Oxides (NO _x ) refers to substances that occur when nitrogen is oxidized in the air by high temperatures. It is mainly discharged in the form of NO, and is mainly present in the form of NO ₂ after exposure to the atmosphere. NO _x is a harmful substance that causes great damage to humans, living organisms, and the environment. In particular, it reacts with ozone in the atmosphere to produce nitric acid and then reacts with ammonia to form ammonium nitrate, which is a recent issue. do. In addition, it is classified as a stage 1 cancer inducing factor by the International Cancer Research Agency (IARC) under the WHO, so its reduction is very urgent.

Nitrogen oxides are mainly generated when a high-temperature combustion process is accompanied, such as thermal power plants, manufacturing plants, and transportation means, and the selective catalytic reduction (SCR) method is most widely used as a method for removing them. The most widely used and commercialized in the SCR method is a V/W/TiO _{2 type} catalyst, which has very high reaction activity and has been applied to industrial sites for a long time. However, since the catalytic active region is limited, the catalytic activity at low temperatures is limited, and when vanadium vaporizes at high temperatures, it has properties that are harmful to the human body. In addition, there is a need for a method to overcome the high demand for the catalyst layer manufacturing cost.

Recently, the development of an SCR catalyst based on maghemite iron oxide is drawing attention. Maghemite (γ-Fe ₂ O ₃ ) is one of the structures of iron trivalent iron oxide and has a spinel structure, and when it becomes nanoparticles, it has superparamagnetic magnetic properties. Among the iron trivalent iron oxides, it has been reported that the SCR catalyst performance is excellent and poisoning to SO ₂ is less, but the application is limited because it has a crystal structure that is inherently vulnerable to heat. However, when manganese ion is doped, thermal stability is improved and SCR catalyst activity is greatly improved at low temperatures, so it is the main catalyst material applicable to low temperature regions while replacing the existing SCR catalyst. Therefore, it is very important to prepare the catalyst by introducing the catalyst developed in the present invention into a honeycomb structure-type support having a large specific surface area and easy control of pore sizes.

Existing vanadium/tungsten/titanium dioxide based SCR catalysts have a limited active temperature range of 280°C to 400°C, and vanadium itself has toxicity, so it is necessary to expand the active temperature range and develop eco-friendly and harmless catalysts. In addition, the recent development of an SCR catalyst with improved performance at a relatively low temperature of 300°C or less is a big issue.

Accordingly, an object of the present invention is to provide an SCR catalyst with improved catalytic activity by introducing catalytic nanoparticles in which manganese is introduced into a maghemite iron oxide structure into a honeycomb structured cordierite support using an ultrasonic coating method. In addition, it is an object of the present invention to provide a method for developing and manufacturing a low-cost, non-toxic SCR catalyst with improved SCR catalyst activity at a low temperature.

A first aspect of the present invention relates to an SCR denitration catalyst, wherein the catalyst includes a honeycomb structured support and iron oxide particles doped with manganese and coated on at least part or all of the surface of the support.

In the second aspect of the present invention, in the first aspect, the iron oxide particles have a diameter (D ₅₀ ) of 5 nm to 100 nm.

A third aspect of the present invention is to have a maghemite crystal structure according to at least one of the above aspects, wherein the iron oxide particles have a manganese content of 17% by weight to 40% by weight relative to 100% by weight of the particles.

The fourth aspect of the present invention is in at least any one of the aforementioned aspects, in the manganese-doped iron oxide particles, manganese has an oxidation number of 2 to 4, and at least one of Mn ^{2 +} , Mn ^{3 +} and Mn ^{4 +} It exists in form.

The fifth aspect of the present invention is according to at least one of the aforementioned aspects, wherein the honeycomb structural support includes a ceramic material including at least one of cordierite, silica, and titania, and has a specific surface area of 15 to 150 m ² / is g.

A sixth aspect of the present invention is in at least one of the above aspects, wherein the surface of the honeycomb structured support is surface-treated with at least one of an organic acid and an inorganic acid.

The seventh aspect of the present invention is to include at least one selected from the group consisting of nitric acid, sulfuric acid, and hydrochloric acid in at least one of the above-described aspects.

In an eighth aspect of the present invention, in at least any one of the above aspects, the inorganic acid is hydrochloric acid.

A ninth aspect of the present invention relates to a method of preparing an SCR denitrification catalyst, the method comprising the steps of (S10) preparing a honeycomb structure type support; (S20) surface-treating the support with at least one selected from an organic acid and an inorganic acid; (S30) preparing a dispersion containing iron oxide particles doped with manganese; (S40) coating the surface of the surface-treated support with the dispersion; And (S50) drying and sintering the support coated with the dispersion.

A tenth aspect of the present invention, in at least any one of the aforementioned aspects, the manganese-doped iron oxide particles are obtained by a method comprising the following (S31) to (S34):

(S31) preparing an aqueous metal ion solution containing iron and manganese ions;

(S32) adding an organic compound to the aqueous metal ion solution;

(S33) forming a manganese/iron metal-organic framework (FeMn-MOF); And

(S34) pyrolyzing the formed manganese/iron metal-organic framework (FeMn-MOF) to obtain maghemite-based iron oxide nanoparticles or manganese hematite-based iron oxide nanoparticles.

In an eleventh aspect of the present invention, in at least one of the aforementioned aspects, all steps of the manufacturing method are performed in an oxygen atmosphere, an atmospheric atmosphere, or an atmospheric atmosphere containing oxygen.

In a twelfth aspect of the present invention, in at least one of the aforementioned aspects, the metal ions in the aqueous solution are contained in a concentration of 0.1 mol/liter to 1.0 mol/liter.

In a twelfth aspect of the present invention, in at least one of the aforementioned aspects, the concentration of manganese ions and concentration of iron ions in the aqueous solution are the same.

In a fourteenth aspect of the present invention, in at least any one of the aforementioned aspects, the organic compound contains an organic acid.

A fifteenth aspect of the present invention is that in at least one of the above aspects, the sintering is performed at a temperature ranging from 320°C to 400°C, and the finally obtained product is manganese maghemite-based iron oxide nanoparticles.

The iron oxide catalyst into which manganese of the present invention is introduced is a metal with a very low cost, and thus it is possible to reduce cost and, therefore, it is very easy to mass-produce. In addition, stability can be secured as the most bio- and environmentally friendly metal among metals.

On the other hand, by introducing the catalyst layer to the support by using ultrasonic waves, the coating of the catalyst layer can be made quickly, and dispersion of particles is promoted to form a uniform catalyst layer.

Lastly, the iron oxide-based catalyst of the present invention is an environmentally friendly and inexpensive SCR nitrogen oxide reduction catalyst, and exhibits improved effects compared to the prior art.

1 is an image showing an SCR denitration catalyst coated with manganese-doped iron oxide particles prepared in Example 2 of the present invention.
2 shows the nitrogen reduction effect of the SCR catalysts obtained in Examples 2-1 and 2-2.
3 is a schematic diagram schematically showing a manufacturing process of manganese-doped iron oxide particles.
Figure 4 (a) is a SEM image of the FeMn-MOF prepared in Example 1, Figure 4 (b) is a TEM image of the FeMn-MOF, Figure 4 (c) is an EDS mapping image of the FeMn-MOF .
5 is an XRD (Powder X-ray diffraction) graph of FeMn-320 and FeMn-400 prepared in Examples 1 and 2.
6 is a TGA (Thermogravimetric analysis) graph of FeMn-MOF obtained in Preparation Example 1.
7A and 7B are XPS graphs of MnFe-320 and MnFe-400 obtained in Example 1-1 and Example 1-2.
8A is a TEM image of MnFe-320 obtained in Example 1, and FIG. 8B is a TEM image of MnFe-400 obtained in Example 2.
9A and 9B are graphs of nitrogen adsorption and desorption analysis of the products obtained in Examples 1-1 and 1-2, respectively.
10A and 10B are graphs showing magnetic properties of iron oxide particles obtained in Examples 1-1 and 1-2, respectively.
11A and 11B are EDS mapping images showing iron oxide particles obtained in Examples 1-1 and 1-2, respectively, using STEM.
12 shows the content of each component contained in FeMn-MOF obtained in Preparation Example 1.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments associated with the accompanying drawings. In addition, the present invention may be implemented in various forms and is not limited to the embodiments described herein. In addition, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the subject matter of the present invention will be omitted.

The present invention relates to an SCR denitration catalyst having an increased catalytic activity for reducing nitrogen oxides at low temperature and its preparation. In the present invention, the SCR denitration catalyst includes a honeycomb structured support and iron oxide particles doped with manganese and coated on at least part or all of the surface of the support.

The honeycomb structured support is a three-dimensional structure including cells of a polygonal column with one open or both open, and the cells are maintained in an empty space, and a three-dimensional particle structure in which liquid or gas can flow or be supported. To have. The polygonal pillar may have a surface shape of a polygonal closed curve having three or more sides, and is not limited to a hexagonal structure.

The support is coated or covered with all or at least part of the surface with iron oxide particles to be described later, and the support surface is preferably porous in order to increase the amount of iron oxide particles introduced. In one embodiment of the present invention, the support may have a specific surface area of 15 to 150 m ² /g.

In one embodiment of the present invention, the support may include a clay material, and may be manufactured by extrusion molding such a clay material. The support may include, for example, at least one or more of coredilite, silica, and titania. In addition, in a specific embodiment of the present invention, a commercially available ceramic honeycomb product such as Ceracom may be used.

In one embodiment of the present invention, the honeycomb structural support is, but is not limited thereto, the diameter of the cell may be 100mm to 200mm based on the maximum length, the height (or depth) of the cell may be 50mm to 150mm. It is not particularly limited thereto. In addition, in the case of the whole honeycomb structure type support in which each of the pillars is assembled, it may have an appropriate size according to the applied denitrification process, and is not limited to a specific resin range.

Meanwhile, the iron oxide particles cover all or at least part of the surface of the support, and are coated on the surface by physical or chemical bonding. In one embodiment of the present invention, the support may be coated with the iron oxide particles of about 80% or more, 90% or more, or 99% or more of the surface area.

In the present invention, the iron oxide particles are doped with manganese and have a maghemite crystal structure, wherein the particles may have a diameter (D50) of about 5 nm to 100 nm, and may be 10 nm or more within the range. And may be 30 nm or less. In one embodiment of the present invention, the diameter has a particle diameter of, for example, 5 nm to 70 nm, more preferably 5 nm to 30 nm. The particle diameter is according to the sintering temperature when the iron oxide particles are manufactured, and the lower the sintering temperature is, the smaller the particle diameter is, and the maghemite structure can be stably maintained. Accordingly, high nitrogen reduction efficiency can be exhibited at low temperatures.

In one embodiment of the present invention, the manganese-doped iron oxide particles contain 17% to 40% by weight or 20% to 40% by weight or 30% to 40% by weight of manganese relative to 100% by weight of the particles. I can. In addition, the iron oxide particles according to the present invention are expected to have high specific surface area of 40m ² /g to 70m ² /g, and thus have high catalytic activity. In addition, the oxidation number of manganese in the iron oxide particles may have 2 to 4, preferably 2 to 3. That is, in the particles, manganese may exist in the form of Mn ^{2 +} , Mn ^{3 +} and Mn ^{4 +} , preferably in at least one of Mn ^{2 +} and Mn ³⁺ .

Referring to FIG. 8A, it can be seen that the manganese-doped iron oxide particles according to the present invention are maintained in at least one of Mn ^{2 +} and Mn ^{3 +} . In addition, this characteristic can be confirmed in FIGS. 10A and 10B.

In general, iron oxide alone is known to have a low nitrogen reduction effect at temperatures below 300°C. However, it has been confirmed that the manganese-doped iron oxide particles of the present invention exhibit a high level of nitrogen reduction effect even at a temperature of 300°C or less, and this can be seen as the effect of doping the iron oxide particles with manganese, especially divalent and trivalent manganese. have.

On the other hand, the SCR denitration catalyst according to the present invention can be prepared by the following method.

First, a honeycomb structural support is prepared. The honeycomb structured support may be prepared in an appropriate size by extrusion molding as described above, or may be prepared as a commercial product. In one embodiment of the present invention, the honeycomb structure type support may be a commercial honeycomb product including a ceramic material such as coredlite, silica, and titanium. In one embodiment of the present invention, the support may have a specific surface area of about 15 to 150 m ² . When the honeycomb structure type support is prepared as described above, its surface is pretreated using acid. The acid is one or more selected from organic acids and inorganic acids, and preferably inorganic acids may be used. In one embodiment of the present invention, the inorganic acid may include at least one of hydrochloric acid, nitric acid and sulfuric acid, preferably nitric acid and/or hydrochloric acid, and most preferably hydrochloric acid.

The pretreatment may be performed in the following manner. An acid solution is prepared and the support is immersed in the acid solution to allow the support to absorb the acid solution. To this end, the support is immersed in an acid solution and then allowed to stand in the solution for a predetermined time, for example, about 30 minutes to 2 hours. In one embodiment of the present invention, the acid solution is an aqueous solution of the aforementioned organic acid or inorganic acid, and has a pH of about 1 to 3. Thereafter, the support is taken out from the acid solution and dried. The drying may be naturally dried at room temperature. Alternatively, drying may be performed under a high temperature condition of about 40° C. or higher in order to promote removal of the acid solution. The upper limit of the drying temperature may be controlled to a range that does not cause a physicochemical change of the support, for example, may be adjusted to about 100°C or less. On the other hand, in one embodiment of the present invention, the step of washing the support with water after taking out the support from the acid solution may be further performed. Next, the dried support is sintered at high temperature. By sintering, moisture and remaining organic matter can be removed and thermal stability can be improved. The sintering may be controlled in a temperature range of about 400° C. to 700° C. and maintained for several hours. On the other hand, it is preferable that the temperature increase rate during sintering is slowly increased to less than about 10° C./min to the set sintering temperature. After sintering is completed, it is cooled to room temperature. The cooling may be performed by selecting an appropriate method among known cooling methods such as natural cooling, air cooling, hot air cooling, and cold air cooling.For example, the cooling is a natural cooling method in which the sintered product is left at room temperature for several hours. Can be applied.

Next, a coating solution is prepared by dispersing the iron oxide particles doped with manganese in an appropriate solvent. In an embodiment of the present invention, the solvent is not limited to a special solvent as long as it does not affect the physicochemical properties of the iron oxide particles, and for example, distilled water may be used as the solvent. In one embodiment of the present invention, the coating solution may be prepared such that the iron oxide particles have a content of less than about 10 wt%, or less than about 5 wt% of the coating solution. Meanwhile, in the present invention, the pretreatment of the support and the preparation of the coating solution are not limited to the above-described order, and the preparation of the coating solution may be performed first, or the pretreatment of the support and the preparation of the coating solution may be performed simultaneously.

When the coating solution is prepared, the prepared support is immersed in the coating solution, and ultrasonic waves are applied thereto so that the iron oxide particles adhere to the surface of the support. The application time or intensity of the ultrasonic wave is not particularly limited, and may be controlled to an appropriate level so that most of the desired injected iron oxide particles adhere to the surface of the support. Thereafter, the support is removed from the coating solution and dried to remove the solvent. After that, the dried support is sintered at high temperature. The sintering may be controlled in a temperature range of 200°C to 400°C, preferably 200°C to 350°C and maintained for several hours. When the sintering temperature exceeds the above range, the crystal structure of the catalyst may be deformed. On the other hand, it is preferable that the temperature increase rate during sintering is slowly increased to less than about 10° C./min to the set sintering temperature. If the temperature increase rate exceeds the above range, loss of the coated catalyst may occur, which is not preferable. After sintering is completed, it is cooled to room temperature. The cooling may be performed by selecting an appropriate method among known cooling methods such as natural cooling, air cooling, hot air cooling, and cold air cooling.For example, the cooling is a natural cooling method in which the sintered product is left at room temperature for several hours. Can be applied.

Next, a method of preparing iron oxide particles coated on the support will be described.

In one aspect of the present invention, the method of manufacturing the iron oxide particles doped with manganese comprises the steps of (S31) preparing an aqueous metal ion solution containing iron ions and manganese ions; (S32) adding an organic compound to the aqueous metal ion solution; (S33) forming a manganese/iron metal-organic framework (FeMn-MOF); And (S34) a sintering step of pyrolyzing to obtain iron oxide nanoparticles having a maghemite crystal structure.

In particular, the manufacturing method of the present invention is characterized in that FeMn-MOF is prepared without addition of hydrochloric acid or nitric acid and without pH adjustment, and all processes are performed in an oxygen atmosphere. Hereinafter, each step will be described in more detail.

First, a metal ion aqueous solution containing iron ions and manganese ions is prepared (S31).

The metal ion aqueous solution may be prepared by dissolving iron and manganese metals in the form of metal salts, metal chlorides, nitrides, bromides, and sulfides in the aqueous solution. Non-limiting examples thereof include Iron(III) nitrate nonahydrate, Iron(III) bromide, and Iron(III) trifluoromethanesulfonate for iron, and Manganese(II) nitrate hexahydrate, Manganese(II) acetate hexahydrate, etc. for manganese. However, it is not particularly limited thereto. In one embodiment of the invention, the aqueous metal ion solution may be prepared by dissolving FeCl ₃ .6H ₂ O and MnCl ₂ .4H ₂ O in water.

In one embodiment of the present invention, the concentration of metal ions in the aqueous solution may be included in a range of 0.1 mol/liter to 1.0 mol/liter, preferably 0.2 mol/liter to 0.5 mol/liter for each of manganese and iron. In this case, manganese and iron in the aqueous solution are contained in the same number of moles. For example, if the water in the aqueous solution is 4L Using MnCl ₂ .4H ₂ O197g to 1 molar amount with FeCl ₃ .6H ₂ O1 moles relative to the ₃ .6H ₂ O with or FeCl ₂ .4H ₂ O can be used MnCl the same molar amount.

Next, an organic compound is added to the aqueous metal ion solution obtained in the above step (S32). In one embodiment of the present invention, the organic compound may include an organic acid. The organic acid is not particularly limited, but may include, for example, at least one selected from sodium fumarate, fumaric acid, terephtalic acid, and sodium terephthalate. In one embodiment of the present invention, sodium fumarate may be used as the organic acid. In this step, by adding an organic acid to the aqueous metal ion solution, the organic acid, manganese ions, and iron ions are combined to form a FeMn-MOF precursor and precipitated. In one embodiment of the present invention, the organic acid may be added in an amount equal to or in excess of the metal ions added to the aqueous solution. That is, the same amount as the concentration (number of moles) of the manganese ions and iron ions added or may be added in an excessive amount. For example, sodium fumarate may be added in an amount of 320 g or 2 mol based on FeCl ₃ .6H ₂ O1 mol.

Thereafter, a manganese/iron metal-organic framework (FeMn-MOF) is formed (S33).

The aqueous solution obtained in (S32) is stirred at a temperature range of 60°C to 80°C for 6 to 12 hours. Through this process, a manganese/iron metal organic framework (FeMn-MOF) is formed. The aqueous solution was centrifuged and washed with deionized water and acetone to obtain a manganese/iron metal-organic framework (FeMn-MOF) from the aqueous solution.

Thereafter, the obtained manganese/iron metal-organic framework (FeMn-MOF) is pyrolyzed by a method of sintering at a high temperature to obtain manganese maghemite iron oxide nanoparticles or manganese hematite iron oxide nanoparticles (S34). In one embodiment of the present invention, the sintering may have different temperature conditions depending on the properties of the particles to be obtained. Preferably, the sintering is performed at a temperature range of about 320°C to about 400°C.

In one embodiment of the present invention, the iron oxide particles are each temperature range after heating the metal-organic framework (FeMn-MOF) obtained above to a temperature range of 320°C to 400°C at a heating rate of 5°C/min. It can be obtained by holding for about 30 minutes to 1 hour. Meanwhile, the sintering may be performed in an atmospheric atmosphere, an oxygen atmosphere, or an atmospheric atmosphere containing oxygen. When oxygen is included in the sintering gas, the concentration of oxygen may be maintained in the range of 1 vol% to 20 vol% of 100 vol% of the sintering gas during sintering.

On the other hand, the iron oxide particles according to the present invention have a magnetic property in which the hematite is a mixture of a superpara magnetic and a ferro-para magnetic.

Hereinafter, the present invention will be described in more detail by the following Examples/Comparative Examples, but the following Examples/Comparative Examples are only examples for easier understanding of the present invention, and are not limited thereto.

Example

Preparation Example 1: Synthesis of metal-organic skeleton (FeMn-MOF)

40 mL of distilled water was added to a glass bottle with a lid, and 1.35 g (5 mmol) of FeCl ₃ .6H ₂ O and 0.99 g (5 mmol) of MnCl ₂ .4H ₂ O were added to dissolve. Thereafter, sodium fumarate (1.6g, 10 mmol) was dissolved in 40 mL of distilled water and slowly added. After that, the mixture was stirred at 60° C. for 6 hours to synthesize an iron/manganese dissimilar metal-organic skeleton (FeMn-MOF).

Example 1-1: Manganese Doped Preparation of iron oxide particles 1 ( FeMn -320)

Thereafter, the iron/manganese metal-organic skeleton obtained in Preparation Example was put in a ceramic boat, heated at a rate of 5° C./min, and sintered at 320° C. for about 1 hour under air conditions to prepare manganese-doped iron oxide particles, It was named'FeMn-320' according to the sintering temperature. The'FeMn-320' was confirmed to have a maghemite crystal structure, and the diameter of the particles was in the range of about 5 nm to 2 nm.

Example 1-2: Manganese Doped Preparation of iron oxide particles 2 ( FeMn -400)

Manganese-doped iron oxide particles were prepared in the same manner as in Example 1, except that the sintering temperature was set to 400°C, and it was named “FeMn-400” according to the sintering temperature. The'FeMn-400' was found to have a maghemite crystal structure, and the diameter of the particles was in the range of about 10 nm to 30 nm.

Example 2: A honeycomb structural support (cordierite, Ceracom) was immersed in a 36% aqueous hydrochloric acid solution for about 1 hour. Thereafter, the support was taken out, washed with hydrochloric acid using distilled water, and then placed in an oven at 60° C. and dried for 12 hours. Then, it was put in a sintering furnace and heated at a rate of 5°C/min, and sintered at 500°C for 1 hour to prepare a pretreated support. On the other hand, the manganese-doped iron oxide particles obtained in Examples 1-1 and 1-2 were dispersed in distilled water at a ratio of 1 wt%. The catalyst prepared using the particles of Example 1-1 was referred to as Example 2-1, and the catalyst prepared using the particles of Example 1-2 was referred to as Example 2-2. Here, the prepared support was immersed and sonicated for about 20 minutes. The sonicated support was taken out, placed in a well-ventilated place, and naturally dried at room temperature for 12 hours. Next, the support was put into a sintering furnace, and the temperature was raised at a rate of 5°C/min, and sintering was performed at 350°C for 1 hour. As a result, a catalyst coated with manganese-doped iron oxide particles was obtained.

<Evaluation Example 1>

FeMn -MOF, FeMn -320 and FeMn -400 structure and property analysis

The synthesis of FeMn-MOF, FeMn-320 and FeMn-400 of Preparation Examples and Examples 1 and 2 and doping of manganese were determined by Fouried Transform Infrared (FT-IR) and Energy Dispersive Spectroscopy Spectroscopy, EDS) was used.

In addition, the crystal form and crystal size of the prepared material were analyzed by using powder X-ray diffraction (XRD) analysis.

FeMn- through image analysis of High Resolution Transmission Electron Microscopy (HR-TEM), (Scanning Transmission electron Microscopy, STEM) and Field-Emission Scanning Electron Microscopy (FE-SEM). The shape and particle size of MOF, FeMn-320 and FeMn-400 were analyzed.

In addition, the specific surface area of the prepared material was confirmed through the Brunauer-Emmett-Teller (BET) method through nitrogen adsorption and desorption curve analysis, and the magnetic properties of the material were measured using a Vibrating Sample Magnetometer (VSM).

Field Radiation Scanning Microscope (FE- SEM ) analysis

The macrostructure of the FeMn-MOF synthesized in Preparation Example was observed. It was confirmed that diamond-shaped particles having a size of about 200 to 300 nm were generated through the images of FIGS. 4(a) to 4(c).

(2) X-ray powder diffraction (XRD)

Using the X-ray diffraction analysis method, it can be confirmed that the binary metal-organic skeleton is in an amorphous state and the metal oxide generated through sintering forms an oxidative-based crystal structure. It can be seen that the iron/manganese metal-organic framework (FeMn-MOF) does not have much crystallinity through FIG. 5(a), and the crystal structure after sintering at 320° C. can be confirmed through FIG. 5(b). It can be seen that the major peaks of hemite coincide to form a maghemite crystal structure, one of the iron oxide structures.

(3) Thermal weight analysis (TGA)

The FeMn-MOF obtained in Preparation Example was subjected to TGA in air. It was confirmed from the TGA curve of FeMn-MOF shown in FIG. 6 that water was removed below 100° C. and the organic building blocks were pyrolyzed at a temperature higher than 440° C. through a two-step process.

(4) X-ray photoelectron spectroscopy (XPS)

FeMn-MOF (Preparation Example) prepared using X-ray photoelectron spectroscopy, and maghemite into which manganese was introduced (Examples 1-1 and 1-2) were analyzed. 7A and 7B, when manganese was analyzed, it was confirmed that manganese was reduced in MnFe-MOF (Preparation Example), and manganese corresponding to 640.47 eV in the iron oxide particle structures of Examples 1-1 and 1-2 after sintering was confirmed. It was confirmed that the bivalent and manganese trivalent peaks corresponding to 642.13 eV exist. When the peak corresponding to iron was analyzed, in the case of MnFe-MOF (Preparation Example), a peak of reduced iron divalent was observed at 709.01 eV. After sintering, in the iron oxide particle structures of Examples 1-1 and 1-2, it was confirmed that the iron trivalent of 710.7 eV became dominant as the sintering temperature increased.

(5) Transmission electron microscope (TEM) analysis

In order to observe small particles that are difficult to observe in FE-SEM, the particles obtained in Examples 1-1 and 1-2 were observed using TEM. It was confirmed that particles of about 100 nm or less were generated through FIGS. 8(a) and 9(b).

(6) Nitrogen (N ₂ ) adsorption/desorption analysis

In order to confirm the specific surface area of the obtained particles, nitrogen adsorption/desorption analysis was performed, and the specific surface area was measured using the BET method. The results, Fig. 9 (a) (Example 1-1) and each was measured in 62.0993 m ² /g,45.1486m ² from Figure 9 (b) (Example 1-2).

(7) Vibrating Sample Magnetometer (VSM)

The magnetic properties of the obtained iron oxide particles were measured. 10(a) and 10(b), the particles obtained in Examples 1-1 and 1-2 were analyzed to have a magnetism of about 36 emu/g, and all of them show superpara magnetic properties.

(8) Energy Dispersive Spectroscopy (EDS)

In order to determine whether manganese ions were introduced into the iron oxide particles, energy dispersion spectral mapping was used. It was confirmed that manganese was introduced into the iron oxide particles obtained through sintering through the images of Scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS) of FIGS. 11 (a) and (b).

<Evaluation Example 2>

The catalysts obtained in Example 2-1 and Example 2-2 were evaluated for their ability to reduce nitrogen oxides.

[NO] = [NH ₃ ]=400ppm, 3vol% O ₂ and N ₂ were injected as moving gas, and the total gas flow was 1,000 mL/min, and the space velocity was 30,000 h ^-1 . The nitrogen oxide reduction rate was calculated using Equation 1 below. As a result of measuring the nitrogen oxide reduction performance at 50° C. intervals, a reduction capacity of 85% or more was shown between 150° C. and 300° C., and in particular, a reduction capacity of 95% or more at 200° C. and 250° C. 2 is a graph summarizing the evaluation results thereof.

Claims (15)

It includes a honeycomb structured support and iron oxide particles doped with manganese, the iron oxide particles doped with manganese are coated on at least part or all of the surface of the support, and the iron oxide particles doped with manganese are 100% by weight of the particles. The content of manganese is 17% to 40% by weight, and in the manganese-doped iron oxide particles, manganese has an oxidation number of 2 to 4, and is present in at least one of M ²⁺ , M ³⁺ and M ⁴⁺ And the manganese-doped iron oxide particles are manganese maghemite-based iron oxide nanoparticles.
The method of claim 1,
The manganese-doped iron oxide particles have a diameter (D ₅₀ ) of 5 nm to 100 nm.
delete delete The method of claim 1,
The honeycomb structured support includes a ceramic material including at least one of cordierite, silica, and titania, and has a specific surface area of 15 to 150 m ² /g.
The method of claim 1,
The surface of the honeycomb structure type support is surface-treated with at least one of an organic acid and an inorganic acid SCR denitration catalyst.
The method of claim 6,
The inorganic acid is an SCR denitration catalyst containing at least one selected from the group consisting of nitric acid, sulfuric acid and hydrochloric acid.
The method of claim 7,
SCR denitration catalyst that the inorganic acid is hydrochloric acid.
It is a method of manufacturing the SCR denitration catalyst according to claim 1,
The above method is
(S10) preparing a honeycomb structural support;
(S20) surface-treating the support with at least one selected from an organic acid and an inorganic acid;
(S30) preparing a dispersion containing iron oxide particles doped with manganese;
(S40) coating the surface of the surface-treated support with the dispersion; And
(S50) drying and sintering the support coated with the dispersion;
Method for producing an SCR denitration catalyst comprising a.
The method of claim 9,
The manganese-doped iron oxide particles are obtained by a method comprising the following (S31) to (S34).
(S31) preparing an aqueous metal ion solution containing iron and manganese ions;
(S32) adding an organic compound to the aqueous metal ion solution;
(S33) forming a manganese/iron metal-organic framework (FeMn-MOF); And
(S34) Pyrolysis (sintering) the formed manganese/iron metal-organic framework (FeMn-MOF) to obtain manganese maghemite-based iron oxide nanoparticles or manganese hematite-based iron oxide nanoparticles.
The method of claim 10,
All steps of the manufacturing method are carried out under an oxygen atmosphere, an atmospheric atmosphere, or an atmospheric atmosphere containing oxygen.
The method of claim 10,
The method of manufacturing an SCR denitration catalyst, wherein the metal ions in the aqueous solution are contained in a concentration of 0.1 mol/liter to 1.0 mol/liter.
The method of claim 10,
The manganese ion concentration and the iron ion concentration in the aqueous solution is the same as the SCR denitrification catalyst manufacturing method.
The method of claim 10,
The organic compound is a method of producing an SCR denitration catalyst containing an organic acid.
The method of claim 10,
The pyrolysis (sintering) is carried out at a temperature range of 320° C. to 400° C., and the final product is manganese maghemite-based iron oxide nanoparticles.

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