Selective reduction catalyst for low temperature reduction of nitrogen monoxide to nitrogen and its manufacturing method

Abstract

The present invention relates to a selective reduction catalyst for low-temperature reduction of nitric oxide (NO) to nitrogen (N2) and a method for manufacturing the same, comprising a support including titania and an active material supported on the support, wherein the active material is composed of a first active material and a second active material, and the oxidation ratio of the first active material is 1.8 or higher.

Description

Technology Field

[0001] The present invention relates to a selective reduction catalyst and a method for manufacturing the same, and more specifically, to a selective reduction catalyst for reducing nitric oxide to nitrogen at low temperature and a method for manufacturing the same. Background Technology

[0002] Selective catalytic reduction (SCR) has been the most widely applied method to control the emission of nitrogen oxides (NOx) from large-scale stationary sources, such as domestic thermal power plants.

[0003] Generally, catalysts used in selective catalytic reduction methods mainly use titania, alumina, silica, and zirconia as supports, and metal oxide, zeolite, alkaline earth metal, and rare earth elements as catalyst components. Oxides of vanadium, molybdenum, nickel, tungsten, iron, and copper are widely used, and in particular, vanadium pentoxide (V2O5) and titanium dioxide (TiO2) forms account for most of the commercially available flue gas denitrification technologies.

[0004] Furthermore, the aforementioned conventional exhaust gas purification catalyst using ammonia as a reducing agent is known to be the most advantageous for reducing nitrogen oxides because it not only exhibits excellent selectivity for NOx but also promotes the reaction between nitric oxide (NO) and ammonia in the presence of oxygen; however, while such ammonia-SCR catalysts show excellent activity in the high-temperature range, they exhibit poor denitrification efficiency in the low-temperature range due to high activation energy. Consequently, the exhaust gas must be reheated to a temperature at which the catalyst can be active, which results in the consumption of a massive amount of energy.

[0005] In addition, regarding the removal of nitrogen oxides from exhaust gas, if the concentration of coexisting sulfur oxides is not sufficiently reduced, the catalyst becomes poisoned by sulfur oxides, making it difficult to maintain sufficient catalytic performance stably for a long period; therefore, in terms of maintaining catalytic performance, it is required that the inhibition of the oxidation reaction of sulfur oxides be achieved simultaneously with the removal of nitrogen oxides from exhaust gas.

[0006] Meanwhile, as renewable energy generation increases due to the government's renewable energy expansion policy, coal-fired power plants are recently operating flexibly to handle load fluctuations.

[0007] At this time, the above thermal power plant has a problem in that the combustion flue gas supplied to the denitrification facility during flexible operation is 400°C when normal output is maintained, but when output is reduced by 30%, the temperature drops to 250°C, which lowers the catalytic activity of the selective reduction catalyst, thereby reducing denitrification efficiency and causing ammonium salts to be generated, which clogs the catalyst layer.

[0008] In other words, when operating a coal-fired power plant, there is a situation where there is no catalyst to overcome high sulfur tolerance, with sulfur oxide concentrations ranging from 500 ppm to 1200 ppm in the low-temperature range below 250°C.

[0009] Accordingly, as a design to overcome the decrease in efficiency of the denitrification catalyst caused by the reduction in flue gas temperature due to the flexible operation of coal-fired power plants, we intend to provide a selective reduction catalyst for reducing nitric oxide (NO) to nitrogen (N2) over a wide temperature range from low temperatures to conventional high temperatures, and a method for manufacturing the same. The problem to be solved

[0010] The present invention aims to provide a selective reduction catalyst for reducing nitric oxide (NO) to nitrogen (N2) and a method for manufacturing the same.

[0011] More specifically, the purpose is to provide a selective reduction catalyst with improved efficiency in a low-temperature range of 250°C or lower, and a method for manufacturing the same.

[0012] In addition, the invention aims to provide a selective reduction catalyst for reducing nitric oxide (NO) to nitrogen (N2) over a wide temperature range from low temperatures to conventional high temperatures, and a method for manufacturing the same.

[0013] However, these tasks are exemplary and do not limit the scope of the invention. means of solving the problem

[0014] According to one aspect of the present invention for achieving the above objective, a selective reduction catalyst is provided comprising a support including titania and an active substance supported on the support, wherein the active substance is composed of a first active substance and a second active substance, and the oxidation ratio of the first active substance is 1.8 or higher.

[0015] According to one embodiment of the present invention, the support comprises crystalline titania, wherein the crystalline titania may be in a form that mixes an anatase crystal structure and a rutile crystal structure.

[0016] According to one embodiment of the present invention, the first active material comprises vanadium oxide, and the vanadium oxide may comprise vanadium pentoxide (V2O5).

[0017] According to one embodiment of the present invention, the second active material may include one selected from zirconium and tin.

[0018] According to one embodiment of the present invention, the oxidation ratio of the first active substance may be controlled by substituting the first active substance with the second active substance to regulate the oxidation state.

[0019] According to another aspect of the present invention, a method for manufacturing a selective reduction catalyst is provided, comprising the steps of: preparing a mixed slurry comprising a first active substance and a second active substance; drying and calcining the mixed slurry to prepare a first composite; mixing the first composite and a support to prepare a catalyst mixed powder; and calcining the catalyst mixed powder to prepare a catalyst composite.

[0020] According to one embodiment of the present invention, the step of preparing the mixed slurry may be to wet-mix the first active substance and the second active substance.

[0021] According to one embodiment of the present invention, the step of manufacturing the first composite may be to dry at a temperature of 90°C to 120°C and to calcin at a temperature of 300°C to 800°C for 4 to 12 hours.

[0022] According to one embodiment of the present invention, the step of preparing the catalyst mixture powder may be to mix dry, such as by mixing using a ball milling method.

[0023] According to one embodiment of the present invention, the ball powder mass ratio (BPMR) of the ball milling may be 1:1 to 100:1, the rotational speed may be 100 rpm to 1000 rpm, and the execution time may be 3 hours to 24 hours.

[0024] According to one embodiment of the present invention, the step of preparing the catalyst mixture powder may comprise 5 wt% to 10 wt% of the first composite based on the support.

[0025] According to one embodiment of the present invention, the step of preparing the catalyst composite may be to calcin at a temperature of 300°C to 800°C for 4 to 12 hours. Effects of the invention

[0026] The present invention has the effect of providing a selective reduction catalyst for reducing nitric oxide (NO) to nitrogen (N2) and a method for manufacturing the same.

[0027] Specifically, by maximizing the generation of active species in the nitric oxide reduction reaction, the reduction efficiency is improved under harsh flue gas conditions of 250°C or lower where sulfur oxides are present at 500 ppm or more and moisture is 6% or more.

[0028] In addition, it has the effect of reducing nitric oxide (NO) to nitrogen (N2) over a wide temperature range from low temperatures to conventional high temperatures.

[0029] Further scopes of the applicability of the present invention will become apparent from the following detailed description. However, since various changes and modifications within the spirit and scope of the present invention are clearly understood by those skilled in the art, specific embodiments, such as the detailed description and preferred embodiments of the present invention, should be understood as being given merely as examples. Brief explanation of the drawing

[0030] FIG. 1 is a flowchart illustrating a method for manufacturing a selective reduction catalyst according to one embodiment. Figure 2 shows a synthesis process diagram of a selective reduction catalyst according to one embodiment. Figure 3 shows a method for evaluating the nitric oxide reduction efficiency of a selective reduction catalyst. Figure 4 shows the results of measuring the oxidation state of the catalyst according to one example and a comparative example using X-ray photoelectron spectroscopy (XPS). Figure 5 is a graph showing the conversion rate of nitric oxide according to the oxidation ratio of a catalyst according to one embodiment. Figure 6 is a graph showing the conversion rate of nitric oxide of catalysts prepared according to one example and a comparative example. Figure 7 is a graph showing the oxidation ratio according to the milling time of a catalyst prepared according to one embodiment. Specific details for implementing the invention

[0031] The present invention will be described in detail below with reference to the embodiments and drawings. These embodiments are provided solely for the purpose of more specifically explaining the present invention, and it will be obvious to those skilled in the art that the scope of the present invention is not limited by these embodiments.

[0032] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains, and in the event of a conflict, the description in this specification, including the definitions, shall prevail.

[0033] To clearly explain the proposed invention in the drawings, parts unrelated to the description have been omitted, and similar parts throughout the specification have been assigned similar reference numerals. Furthermore, when a part is described as “comprising” a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Additionally, the term “part” as described in the specification refers to a single unit or block that performs a specific function.

[0034] In each step, identification codes (1st, 2nd, etc.) are used for convenience of explanation and do not describe the order of the steps; the steps may be performed differently from the specified order unless a specific order is clearly indicated in the context.

[0035] In addition, in this nomenclature, 'crystalline' vanadium pentoxide is a term used to distinguish it from amorphous vanadium pentoxide and is interpreted to include all commonly used crystalline and powdered vanadium pentoxide. Furthermore, the terms 'powdered' and 'powdered form' are used to exclude the solution state dissolved in a solvent, and the powdered titanium dioxide or vanadium pentoxide includes all titanium dioxide or vanadium pentoxide commonly used in the industry, and the size or shape of the powder is not particularly limited.

[0036] In the case of a typical V2O5 / TiO2-based selective reduction catalyst, the vanadium oxidation ratio (V 4+ / V 5+ When ) increases, polymeric vanadia species increase. At this time, as the vanadia species increase, the activation energy for nitric oxide reduction decreases, and because it has a Bronsted proton acid site that provides the highest proton, the efficiency of nitric oxide reduction becomes maximum even at low temperatures.

[0037] Accordingly, conventional selective reduction catalysts have a vanadium oxidation ratio (V 4+ / V 5+ To increase the reduction efficiency, a catalyst was prepared by increasing the vanadium content, and the reduction efficiency of nitric oxide increased when applied at a low temperature of 250°C or lower. However, when the temperature reaches 350°C to 400°C, which is the normal operating temperature, the oxidation reaction is accelerated, converting SO2 into SO3. The reaction between the SO3 and unreacted NH3 and H2O produces ammonium bisulfate ((NH4HSO4)) and ammonium sulfate ([(NH4)2HSO4]). The ammonium sulfate causes catalyst poisoning, corrodes equipment at the bottom of the reactor, and forms scale, which adversely affects the entire process.

[0038] Accordingly, the present invention aims to provide a selective low-temperature reduction catalyst that improves the vanadium oxidation ratio without increasing the vanadium content of the medium-temperature catalyst used in power plants.

[0039] The selective reduction catalyst according to the present invention is characterized by comprising a support and an active material supported on the support.

[0040] First, the support is preferably crystalline titania, and the titania preferably comprises titania dioxide (TiO2).

[0041] At this time, the crystalline phase of the titania has an anatase crystal structure and a rutile crystal structure, and the support is characterized in that it is in a mixed form of the anatase crystal structure and the rutile crystal structure. Furthermore, it is preferable that the anatase crystal structure and the rutile crystal structure are mixed in a weight ratio of 70:30 to 100:0.

[0042] The above active substance is supported on the above support, and the above active substance consists of a first active substance and a second active substance.

[0043] In detail, the first active material comprises vanadium oxide as a catalytic active material, and it is preferable that the vanadium oxide is crystalline vanadium pentoxide (V2O5). In addition, the oxidation ratio (V) of vanadium, which is the first active material 4+ / V5 + ) is characterized by being 1.8 or higher.

[0044] The second active substance is characterized by acting as a co-catalyst as a catalytic active substance. Specifically, the second active substance comprises one selected from zirconium and tin. For example, it is preferable that the zirconium comprises zirconium nitrate (ZrO(NO3)2) and that the tin comprises tin sulfide (SnS2). In this case, the second active substance controls the oxidation ratio of the first active substance, and is characterized by controlling the oxidation state by substituting the first active substance with the second active substance.

[0045] In detail, by using the above zirconium or tin as a co-catalyst, the electron transfer process between vanadium active species is replaced, thereby maintaining vanadium active species in the transition state and increasing Brønsted sites on the vanadium in the transition state.

[0046] In other words, using a co-catalyst increases the lattice defects suitable for the reaction, thereby increasing oxygen utilization capacity (storage and transfer, etc.), which in turn increases Brønsted acid sites on the transition state vanadium.

[0047] The method for manufacturing a selective reduction catalyst will be described in detail below.

[0048] FIG. 1 is a flowchart showing a method (S100) for manufacturing a selective reduction catalyst according to one embodiment.

[0049] Referring to FIG. 1, the method for manufacturing the selective reduction catalyst (S110) comprises the steps of manufacturing a mixed slurry (S110), manufacturing a first complex (S120), manufacturing a catalyst mixed powder (S130), and manufacturing a catalyst complex (S140).

[0050] The step (S110) of preparing the above mixed slurry is characterized by preparing a mixed slurry by mixing the first active substance and the second active substance.

[0051] More specifically, the first active substance and the second active substance are mixed in a wet manner, wherein the first active substance comprises vanadium oxide and the second active substance comprises one selected from zirconium and tin, wherein the vanadium oxide is preferably vanadium pentoxide (V2O5), the zirconium is preferably zirconium nitrate (ZrO(NO3)2), and the tin is preferably tin sulfide (SnS2).

[0052] In addition, it is preferable that the second active substance be included in an amount of 2.5 wt% to 15 wt% of the first active substance. In other words, it is preferable that zirconium or tin atoms be included in an amount of 2.5 wt% to 15 wt% relative to the vanadium oxide.

[0053] The step (S120) of manufacturing the first composite is to dry and calcin the mixed slurry, wherein the mixed slurry is first dried at a temperature of 90°C to 120°C and then calcined at a temperature of 300°C to 800°C for 4 to 12 hours.

[0054] The step (S130) of manufacturing the catalyst mixture powder is characterized by mixing the first composite and the support, and mixing the first composite and the support in a dry manner.

[0055] In detail, the first composite and the support are dry-mixed using a ball milling method, wherein the ball milling conditions include a ball powder mass ratio (BPMR) of 1:1 to 100:1, a rotational speed of 100 rpm to 1000 rpm, and a processing time of 3 hours to 24 hours. At this time, the ball milling method is not limited thereto and the present invention can be implemented according to milling methods commercially available in the industry.

[0056] In addition, the first complex is characterized by being included in an amount of 5 wt% to 10 wt% based on the support. At this time, when the content of the first complex is less than 5 wt%, the oxidation ratio (V 4+ / V 5+ If the increase of ) is not significant and exceeds 10wt%, other oxidation ratios (V 3+ / V 5+ As ) increases, the oxidation rate of SO2 may also increase.

[0057] The step (S140) of manufacturing the catalyst composite is to manufacture the catalyst composite by calcining the catalyst mixture powder, and it is preferable to calcin at a temperature of 300°C to 800°C for 4 to 12 hours. For example, calcination may be performed using a tube-type, convection-type, or grate-type furnace, rotary kiln, etc., but is not limited thereto.

[0058] Meanwhile, the catalyst composite prepared according to the present invention can be applied as a selective reduction catalyst for the reduction of nitric oxide containing SO2 and H2O in flue gas. Specifically, the operating temperature is 200°C to 400°C, and the space velocity (the volume of liquid or gas passing through a unit volume of packing per unit time, GHSV) is 1000 hr -1 up to 1500hr -1 And, it can reduce nitric oxide under flue gas conditions containing SO2, H2O and oxygen.

[0059] In addition, the above-described catalyst composite is formed from vanadium-zirconium-titania or vanadium-tin-titania, and while the form of the catalyst is not limited, it can be used in various forms such as honeycomb, slate, plate, pellet, etc., which are extruded into particles or monoliths together with a small amount of binder.

[0060] FIG. 2 shows a synthesis process diagram of a selective reduction catalyst according to one embodiment. Hereinafter, examples and comparative examples will be described in detail with reference to FIG. 2. However, the following examples, experimental examples, and comparative examples are merely illustrative of the present invention, and the present invention is not limited by the following examples, experimental examples, and comparative examples.

[0062] Examples and Comparative Examples

[0063] Example 1. Preparation of a catalyst containing vanadium-zirconium-titania (hereinafter referred to as P11)

[0064] Zirconium nitrate (ZrO(NO3)2) is quantified to be 10 wt% of crystalline vanadium pentoxide based on the atomic content of zirconium, and then dissolved in distilled water heated to 60°C or higher to prepare an aqueous zirconium solution, and then the vanadium pentoxide and the aqueous zirconium solution are mixed to prepare a zirconium slurry.

[0065] Afterward, the slurry is dried using a vacuum rotary evaporator to remove moisture, and then dried sufficiently for more than one day in a dryer at 103°C to completely remove moisture contained in the micropores. Finally, the first metal complex containing vanadium-zirconium is prepared by calcining in a tube furnace at a temperature of 400°C for 4 hours under an air atmosphere.

[0066] Afterwards, 20g of titanium dioxide in powder form with a crystalline anatase and rutile ratio of 50:50 is prepared, and the first metal complex containing vanadium-zirconium prepared earlier is quantified to be 6.5wt% of the titanium dioxide by mass.

[0067] These two materials are fed into a ball milling device along with balls. The material of the balls used is zirconia, and balls with diameters of 20 mm, 10 mm, and 5 mm are fed in a weight ratio of 50:25:25, respectively. At this time, the BPMR (ball powder mass ratio, weight ratio of balls to mixture) is 50:1. The milling speed is 360 rpm, and milling is performed for 3 hours. After ball milling is completed, the mixture is calcined in a tubular furnace at 500°C in an air atmosphere for 4 hours. The heating rate during calcination is 10°C / min. At this time, the catalyst prepared above is labeled as P11.

[0069] Example 2. Preparation of a catalyst containing vanadium-tin-titania

[0070] A catalyst is prepared in the same manner as in Example 1, except that tin sulfide (SnS2) is quantified to be 10 wt% of crystalline vanadium pentoxide based on the atomic content of tin, dissolved in ammonium sulfide ((NH4)2S) at room temperature to prepare an aqueous tin solution, and then the vanadium pentoxide and the aqueous tin solution are mixed to prepare a tin slurry. At this time, the prepared catalyst is denoted as P12.

[0072] Example 3. Preparation of a catalyst containing vanadium-zirconium-titania

[0073] A catalyst was prepared in the same manner as in Example 1, except that during the process of mixing the first complex containing vanadium-zirconium and titanium dioxide through a dry ball mill, the milling method used was the attrition mill method, the diameter of the balls used was 5 mm, and the milling was performed at a milling speed of 500 rpm for 3 hours, and the prepared catalyst was designated as P21.

[0075] Example 4. Preparation of a catalyst containing vanadium-tin-titania

[0076] A catalyst was prepared in the same manner as in Example 1, except that during the process of mixing the first complex containing vanadium-tin and titanium dioxide through a dry ball mill, the milling method used was the attrition mill method, the diameter of the balls used was 5 mm, the milling speed was 500 rpm, and the milling was performed for 3 hours, and the prepared catalyst was designated as P22.

[0078] Example 5. Preparation of a catalyst containing vanadium-zirconium-titania

[0079] A catalyst was prepared in the same manner as in Example 1, except that the milling time was 24 hours during the process of mixing the first complex containing vanadium-zirconium and titanium dioxide through a dry ball mill, and the prepared catalyst was designated as P31.

[0081] Example 6. Preparation of a catalyst containing vanadium-tin-titania

[0082] A catalyst was prepared in the same manner as in Example 1, except that the milling time was 24 hours during the process of mixing the first complex containing vanadium-tin and titanium dioxide through a dry ball mill, and the prepared catalyst was designated as P32.

[0084] Comparative Example 1.

[0085] A commercial low-temperature catalyst based on a conventional tungsten co-catalyst was prepared by supporting 10 wt% of V2O5 on a TiO2 support, and a catalyst was prepared by adding 10 wt% of tungsten, a co-catalyst, to the prepared 10 wt% V2O5 / TiO2.

[0086] Specifically, the method for preparing the catalyst was the sulfuric acid method, in which ilmenite (FeO·TiO2) is dissolved in sulfuric acid, Fe ions are removed from the solution, and then dried and calcined. The content is calculated according to the composition ratio, and the calculated amount of ammonium metavanadate (NH4VO3) is dissolved in distilled water heated to 80°C. At this time, since the solubility of NH4VO3 is very low, oxalic acid ((COOH)2) is added dropwise to the ammonium vanadate aqueous solution to increase solubility, and the mixture is continued until the pH value reaches 2.5, after which the temperature is lowered to about 50°C.

[0087] Monoethanolamine (NH2CH2CH2OH) was added to this solution in an amount equal to that of ammonium metavanadate and stirred. Then, W, a co-catalyst, was mixed into the prepared solution in an amount calculated at a composition ratio of 10 wt (%). The catalyst was prepared by mixing it with TiO2 according to the composition ratio of the prepared solution. The catalyst thus prepared was processed into a powder catalyst through the steps of pressure extraction → drying at 130°C → calcination at 450°C → grinding. At this time, the prepared catalyst was denoted as E.

[0089] Comparative Example 2.

[0090] In the process of mixing the first complex containing vanadium-zirconium and titanium dioxide, the mixture was mixed in the form of a slurry in an aqueous solution, moisture was removed using a rotary evaporator, and the mixture was sufficiently dried for at least one day in a dryer at 103°C to completely remove moisture contained in the micropores. Subsequently, the vanadium-zirconium-titania catalyst was prepared in the same manner as in Example 1, except that it was calcined in a tube furnace at 500°C for 4 hours under an air atmosphere. At this time, the prepared catalyst was designated as C11.

[0091] Comparative Example 3.

[0092] In the process of mixing the first complex containing vanadium-tin and titanium dioxide, the mixture was mixed in the form of a slurry in an aqueous solution, moisture was removed using a rotary evaporator, and the mixture was sufficiently dried for at least one day in a dryer at 103°C to completely remove moisture contained in the micropores. Subsequently, the vanadium-zirconium-titania catalyst was prepared in the same manner as in Example 1, except that it was calcined in a tube furnace at 500°C for 4 hours under an air atmosphere. At this time, the prepared catalyst was designated as C12.

[0094] Comparative Example 4.

[0095] Crystalline anatase TiO2 (hereinafter TiO2(A)) is used as a support. 20g of titanium dioxide (TiO2(A)) is prepared. Separately, crystalline vanadium pentoxide (V2O5) powder is prepared such that it is 6.5 wt% of titanium dioxide based on the vanadium atom content. These two materials are mixed in a slurry form in an aqueous solution and water is removed using a rotary evaporator. Then, to completely remove water contained in the micropores, the mixture is dried sufficiently in a dryer at 103°C for at least one day. Afterward, a vanadium-titania (TiO2(A)) catalyst is prepared by calcining in a tube furnace at 500°C for 4 hours under an air atmosphere. At this time, the prepared catalyst is denoted as C2.

[0097] Comparative Example 5.

[0098] A vanadium-titania catalyst was prepared in the same manner as Comparative Example 4, except that the support was crystalline rutile TiO2 (hereinafter TiO2(B)), and the prepared catalyst was denoted as C3.

[0100] Comparative Example 6.

[0101] A vanadium-titania catalyst was prepared in the same manner as in Comparative Example 4, except that the ratio of crystalline anatase to rutile in Comparative Example 4 was used in a ratio of 70:30, and the prepared catalyst was denoted as C41.

[0103] Comparative Example 7.

[0104] A vanadium-titania catalyst was prepared in the same manner as in Comparative Example 4, except that the ratio of crystalline anatase to rutile in Comparative Example 4 was used in a ratio of 30:70, and the prepared catalyst was denoted as C42.

[0106] Experimental Example 1.

[0107] The nitrogen reduction characteristics of the catalysts prepared according to the aforementioned Comparative Examples 4 to 6 were evaluated. Specifically, the NO supplied to the experiment was 800 ppm, SO2 500 ppm, oxygen 3%, moisture 6%, and the space velocity was 20,000 hr⁻¹. -1 , Total flow was maintained at 500cc / min and NH3 / NO 1.0.

[0108] Figure 3 shows a fixed-bed reactor for selective reduction catalyst experiments. Referring to Figure 3, the fixed-bed reactor used for the catalyst denitrification reaction experiment consisted of a gas injection section, a reactor section, and a reaction gas analysis section. The flow rates of the gases supplied to the reactor were controlled using an MFC (Mass Flow Controller, MKS Co.) from each bomb of NO, N2, O2, NH3, and SO2, and the water supply was provided by injecting N2 containing water into the reactor through a bubbler.

[0109] To maintain a constant supply volume, water at a constant temperature was circulated using a circulator outside a double-jacketed bubbler. The gas supply pipe was made entirely of stainless steel, and a heating band was wrapped around it to maintain a constant temperature of 180°C to prevent the formation of salts such as NH4NO3 and NH4NO2 resulting from the reaction between NO and NH3, and to prevent moisture in the reaction gas from condensing. The reactor was a continuous flow fixed-bed reactor constructed from a quartz tube with an inner diameter of 8 mm and a height of 60 cm, and quartz wool was used to fix the catalyst layer. The reactor temperature was controlled by a PID temperature controller using a K-type thermocouple mounted on the top of the fixed layer, and an identical thermocouple was installed below the catalyst layer to measure the temperature difference before and after the catalyst layer and the temperature at the gas inlet.

[0110] To measure the concentrations of reactants and products, NO was analyzed using a non-dispersive infrared gas analyzer (Uras 10E, Hartman & Braun Co.), and NOx was analyzed using a detector tube (9L, Gas Tec. Co.) at the main reactor outlet. SO2 was also analyzed using a chemiluminescence analyzer (43C HL, Thermo Ins.) and a detector tube (5L, Gas Tec. Co.). Ammonia concentration was measured using a detector tube (3M, 3La, 3L, Gas Tec. Co.). To avoid the effect of pressure loss when the catalyst was packed into the main reactor, the prepared catalyst was sieved to a size of 40–50 mesh before use.

[0111] The nitric oxide conversion reaction rate (mol / gcat·min) of the catalyst measured by this method is shown in Table 1.

[0112] Nitric oxide conversion reaction rate (mol / gcat·min) Comparative Example 4 (C2) 2.80×10 -5 Comparative Example 5 (C3) 3.03×10 -5 Comparative Example 6 (C41) 1.21×10 -5 Comparative Example 7 (C42) 1.20×10 -5

[0113] Referring to Table 1, it was confirmed that when a single crystalline phase is added, the nitric oxide conversion rate is higher when using the catalyst of Comparative Example 5 containing rutile crystals than when using the catalyst of Comparative Example 4 containing anatase crystals.

[0114] In addition, it was confirmed that the highest nitric oxide conversion rate was observed when a mixed crystalline phase (a mixture of anatase and rutile crystalline phases) was used compared to when a single crystalline phase was used.

[0115] Furthermore, it was confirmed that when a mixed crystalline phase was used, the nitric oxide conversion rate was higher as the proportion of anatase increased. This is attributed to the fact that a higher proportion of anatase leads to an increase in lattice defects, which in turn enhances the oxygen adsorption and transport capacity of nitric oxide.

[0116] That is, it can be confirmed that the reaction rate of the vanadium-titania catalyst according to the support of the nitric oxide reduction reaction shows the highest values ​​in Comparative Examples 6 and 7.

[0118] Experimental Example 2.

[0119] The nitric oxide reduction characteristics of the catalysts prepared through Examples 1 to 6, Comparative Example 2, and Comparative Example 3 were evaluated. Specifically, the NO supplied to the experiment was 800 ppm, SO2 500 ppm, oxygen 3%, moisture 6%, and the space velocity was 5,000 hr⁻¹. -1 The process was carried out with the total flow maintained at 500cc / min and NH3 / NO 1.0, and the reduction conversion rate of NO to N2 measured by this method is shown in Table 2.

[0120] Nitric oxide conversion reaction rate (mol / gcat·min) Example 1 (P11) 1.250×10 -4 Example 2 (P12) 1.32×10 -4 Example 3 (P21) 6.02×10 -5 Example 4 (P22) 4.12×10 -5 Example 5 (P31) 2.51×10 -4 Example 6 (P32) 2.45×10 -4 Comparative Example 2 (C11) 5.31×10 -5 Comparative Example 3 (C12) 7.02×10 -5

[0121] Referring to Table 2, it can be seen that the conversion rate of Examples 4 to 5, which were prepared by using zirconium or tin as a co-catalyst and operating a ball mill for 24 hours, is the highest.

[0123] Experimental Example 3.

[0124] In order to investigate the oxidation state of vanadium, the active metal of the vanadium-zirconium-titania or vanadium-tin-tinania catalysts prepared using the dry manufacturing method disclosed in the present invention as a physical property of the catalyst, the oxidation state of vanadium, the active metal of the catalysts prepared according to Examples 1 and 2 and Comparative Examples 2 and 3, was measured using XPS (VG Scientific Co. trade name ESCALAB 201).

[0125] Figure 4 shows the results of measuring the oxidation state of the catalyst according to one example and a comparative example using X-ray photoelectron spectroscopy (XPS), and Table 3 shows the quantitative values ​​thereof.

[0126] V 4+ / V 5+ ratio Example 1 (P11) 1.73 Example 2 (P12) 1.75 Comparative Example 2 (C11) 1.50 Comparative Example 3 (C12) 1.47

[0127] First, referring to Fig. 4, vanadium species V present on the catalyst surface 5+ and V 4+ are respectively V 5+ 2p 3 / 2 and V 4+ 2p 3 / 2 It has binding energies of 517.3 eV and 516.3 eV, which are in the category. Also, referring to Table 3, the oxidation ratio (V) of the catalysts in Example 1 and Example 2 4+ / V 5+ It can be confirmed that the ratio) is higher than that of comparison example 2 and comparison example 3.

[0128] In other words, when comparing this with the conversion rate in Table 2, the oxidation ratio of the catalyst (V 4+ / V 5+ It can be confirmed that as the ratio increases, the activation energy decreases, leading to a significant increase in the conversion efficiency of nitric oxide.

[0129] In addition, when mixing the first complex and titania, the oxidation ratio of the catalyst (V) when prepared dry compared to when prepared wet 4+ / V 5+It can be confirmed that the ratio is high. This is because when using the dry method, the bonding strength can be increased through physical collisions compared to when using the wet method. In other words, it is believed that as physical bonding increases, the doping effect of the co-catalyst between the lattice increases, which leads to an increase in lattice defects and improved oxygen transport capacity, thereby increasing the conversion rate.

[0131] Experimental Example 4.

[0132] The vanadium oxidation state of the catalysts prepared through Examples 1 to 6 and Comparative Example 1 was measured by XPS, and the quantified values ​​are shown in Table 4. In addition, the conversion rate of nitric oxide according to the oxidation ratio of the catalyst samples is shown in Figure 5, and the conversion rate of nitric oxide for each prepared sample is shown in Figure 6 without being arranged in order of oxidation rate.

[0133] V 4+ / V 5+ ratio Example 1 (P11) 1.73 Example 2 (P12) 1.75 Example 3 (P21) 1.50 Example 4 (P22) 1.47 Example 5 (P31) 1.85 Example 6 (P32) 1.81 Comparative Example 1(E) 1.45

[0134] Oxidation ratio (V) of a catalyst containing tungsten as a co-catalyst 4+ / V 5+ The ratio is 1.45, which can be confirmed to be lower than the oxidation ratio of the catalysts in Examples 1 to 6 prepared according to the present invention. In other words, through this, it can be confirmed that the oxidation ratio increases when zirconium or tin is used as a co-catalyst.

[0135] In addition, when comparing Examples 1 to 6, the oxidation ratio is lower when the ball milling speed (rpm) is faster and the time is shorter during ball milling, and the oxidation ratio (V) is lower when the ball milling speed (rpm) is slower and the ball milling time is longer. 4+ / V 5+ It can be confirmed that the ratio increases. This indicates that the lower the rpm, the more uniform the mixing and differentiation becomes, and the bonding strength increases as the execution time increases; it is determined that as the bonding strength increases, the lattice defects and oxidation ratio increase.

[0136] In addition, referring to Figures 5 and 6, it can be confirmed that the nitric oxide reduction efficiency increases as the oxidation ratio increases. Referring to Figure 5, it can be seen that the conversion rate of nitric oxide decreases until the oxidation ratio increases to 1.2, but thereafter, the conversion rate of nitric oxide increases as the oxidation ratio increases. In other words, this is the oxidation ratio (V 4+ / V 5+ When the ratio) is 1.2 or less, the relatively different oxidation ratio (V 3+ / V 5+ It is determined that the conversion rate of nitric oxide decreases because the ratio increases.

[0137] In particular, it was confirmed that the P31 and P32 catalysts prepared through Examples 5 and 6 exhibited the best nitric oxide conversion efficiency.

[0138] In other words, through this, the oxidation ratio (V 4+ / V 5+ It can be confirmed that the nitric oxide conversion efficiency increases as the ratio increases.

[0139] Figure 7 is a graph showing the oxidation ratio according to the milling time of a catalyst prepared according to one embodiment.

[0140] Specifically, the oxidation rate (V) according to milling time 4+ / V 5+ A catalyst was prepared using the same method as in Example 1, except that ball milling was performed for milling times of 3, 17, and 30 hours to verify the ratio, and the resulting oxidation ratio (V 4+ / V 5+ The ratio was measured.

[0141] Referring to Fig. 7, as the milling time increases, the oxidation ratio (V 4+ / V 5+ It was confirmed that the ratio increased, and after 24 hours, the oxidation ratio became constant.

[0142] The present invention provides a selective reduction catalyst and a method for manufacturing the same, which can control the oxidation state of vanadium present on the catalyst surface by substituting it with a co-catalyst such as zirconium or tin, and has the effect of providing a selective reduction catalyst and a method for manufacturing the same that increases the efficiency of nitric oxide reduction by maximizing the generation of active species during the nitric oxide reduction reaction.

[0143] In addition, there is an effect of providing a selective reduction catalyst that exhibits high nitric oxide reduction efficiency even under harsh flue gas conditions of 250°C or lower, where sulfur oxides are present at 500 ppm or more and moisture is present at 6% or more, and a method for manufacturing the same.

[0144] In addition, by using a dry method rather than a conventional wet method to manufacture the catalyst, there is an effect of providing a selective reduction catalyst that is manufactured relatively simply and inexpensively, and a method for manufacturing the same.

[0145] In this specification, only a few examples among the various embodiments performed by the inventors are described; however, the technical concept of the present invention is not limited or restricted thereto, and it is understood that it can be modified and implemented in various ways by those skilled in the art.

Claims

Claim 1 A selective reduction catalyst comprising: a titania support; and an active material supported on the support; wherein the active material is composed of a first active material and a second active material, and the oxidation ratio of the first active material is 1.8 or higher, the support is crystalline titania, the first active material comprises vanadium oxide, the second active material comprises tin, and the vanadium oxide comprises vanadium pentoxide (V2O5). Claim 2 A selective reduction catalyst according to claim 1, wherein the crystalline titania is in a mixed form of an anatase crystal structure and a rutile crystal structure. Claim 3 delete Claim 4 A selective reduction catalyst according to claim 1, wherein the second active substance comprises zirconium. Claim 5 A selective reduction catalyst according to claim 1, wherein the oxidation ratio of the first active substance controls the oxidation state by substituting the first active substance with the second active substance. Claim 6 A method for manufacturing a selective reduction catalyst comprising: a step of preparing a mixed slurry containing a first active substance and a second active substance; a step of drying and calcining the mixed slurry to prepare a first composite; a step of mixing the first composite and a support to prepare a catalyst mixed powder; and a step of calcining the catalyst mixed powder to prepare a catalyst composite; wherein the support is crystalline titania, the first active substance includes vanadium oxide, the second active substance includes tin, and the vanadium oxide includes vanadium pentoxide (V2O5). Claim 7 A method for manufacturing a selective reduction catalyst according to claim 6, wherein the step of manufacturing the mixed slurry is to wet-mix the first active substance and the second active substance. Claim 8 A method for manufacturing a selective reduction catalyst according to claim 6, wherein the step of manufacturing the first complex is to dry at a temperature of 90°C to 120°C and calcin at a temperature of 300°C to 800°C for 4 to 12 hours. Claim 9 A method for manufacturing a selective reduction catalyst according to claim 6, wherein the step of manufacturing the catalyst mixture powder is to mix by a dry mixing method, specifically by mixing using a ball milling method. Claim 10 A method for manufacturing a selective reduction catalyst according to claim 9, wherein the BPMR (ball powder mass ratio) of the ball milling is 1:1 to 100:1, the rotational speed is 100 rpm to 1000 rpm, and the execution time is 3 hours to 24 hours. Claim 11 A method for manufacturing a selective reduction catalyst according to claim 6, wherein the step of manufacturing the catalyst mixture powder comprises 5 wt% to 10 wt% of the first complex based on the support. Claim 12 A method for manufacturing a selective reduction catalyst according to claim 6, wherein the step of manufacturing the catalyst complex is to calcin at a temperature of 300°C to 800°C for 4 to 12 hours.

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