An scr catalyst, its preparation method and application

Abstract

The application provides an SCR catalyst and a preparation method and application thereof. The preparation method comprises the following steps: S1: uniformly mixing a carrier, an active component and an additive to prepare a mixed powder; S2: adding a dispersant, a binder, a lubricant, an additive and water into the mixed powder, stirring and mixing, adjusting a pH value, and preparing a mud; S3: filtering and refining the mud, and extruding to prepare a flat plate blank; S4: sending the flat plate blank into a convex point corrugated roller press to be pressed into a corrugated structure with convex points, and cutting to prepare a corrugated blank; and S5: drying and calcining the corrugated blank to prepare the SCR catalyst. The application increases the contact area of flue gas and the catalyst, improves the denitration efficiency of the catalyst, reduces the volume usage amount of the catalyst and the raw material cost, and significantly improves the stability and service life of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to an SCR catalyst, its preparation method, and its application. Background Technology

[0002] Selective catalytic reduction (SCR) technology is currently the most widely used method for treating nitrogen oxides (NOx) in industrial flue gas and ship exhaust. x The mainstream technology for denitrification, the research and design of its core SCR denitrification catalyst directly determines the denitrification efficiency, operating cost and equipment compatibility.

[0003] Currently, commercially available SCR catalysts are mainly classified into three types: flat plate, corrugated plate, and honeycomb. Among them, flat plate and corrugated plate catalysts require steel mesh or glass fiber as a support, which not only increases the complexity of the preparation process and the cost of raw materials, but also may cause catalyst detachment due to support aging, thus affecting the catalyst's service life. In addition, corrugated plate flue gas denitrification catalysts are mostly prepared by coating method, which has problems such as weak bonding between the active layer and the substrate and easy detachment. Moreover, the substrate preparation and active component loading are carried out in steps, making the process relatively cumbersome.

[0004] While honeycomb catalysts require no additional support, their simple structure limits the contact area between flue gas and the catalyst's active sites, thus restricting the improvement of denitrification efficiency. Furthermore, to achieve the desired denitrification effect, the catalyst volume often needs to be increased, making it difficult to adapt to new small and medium-sized denitrification systems such as small chemical reactors, small mobile catalytic converters, and marine exhaust gas denitrification reactors. In addition, commercial honeycomb catalysts are vanadium-tungsten-titanium systems, with a large amount of tungsten-based active components, resulting in high raw material costs. In particular, traditional catalyst preparation processes mostly employ a single molding method, resulting in either a well-formed catalyst with a low mass transfer coefficient and poor airflow turbulence, or a loose structure with insufficient mechanical strength, making it difficult to simultaneously meet the multiple requirements of denitrification efficiency, cost control, and equipment compatibility.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide an SCR catalyst, its preparation method, and its application, which increases the contact area between flue gas and the catalyst, improves the denitrification efficiency of the catalyst, reduces the volumetric usage of the catalyst and the cost of raw materials, and significantly improves the stability and service life of the catalyst.

[0007] This invention provides a method for preparing an SCR catalyst, characterized by comprising the following steps: S1: Mix the carrier, active component and additives evenly to obtain a mixed powder; S2: Add dispersant, binder, lubricant, additive and water to the mixed powder, stir and mix, adjust the pH value to obtain mud; S3: After filtering and refining the clay, the clay is extruded to obtain a flat blank. S4: The flat blank is fed into the corrugated roller press and rolled into a corrugated structure with raised dots. After cutting, the corrugated blank is obtained. S5: The corrugated preform is dried and calcined to obtain the SCR catalyst.

[0008] In the preparation method of the present invention, the mass parts of each raw material are as follows: 100 parts of carrier, 2-4 parts of active component, 1-5 parts of auxiliary agent, 0.5-2 parts of dispersant, 1-3 parts of binder, 0.5-2 parts of lubricant, 20-50 parts of additive, and 10-30 parts of water.

[0009] Preferably, the mass fractions of each raw material are as follows: 100 parts carrier, 2-3 parts active component, 1.5-3 parts additive, 0.5-1 part dispersant, 1.5-2 parts binder, 1-2 parts lubricant, 44-45 parts additive, and 15-20 parts water.

[0010] Further, the carrier is TiO2; the active component is V2O5; the auxiliary agent is selected from at least one of CeO2, MnO2, MoO3 and WO3, preferably including at least two of CeO2, MnO2 and MoO3, in which case there is no need to use tungsten-based active components, which is beneficial to significantly reduce raw material costs; the dispersant is selected from at least one of sodium tripolyphosphate, polyethylene glycol and polyethylene oxide; the binder is selected from at least one of carboxymethyl cellulose and polyvinyl alcohol, preferably including 1-2 parts of carboxymethyl cellulose and 0-1 parts of polyvinyl alcohol; the lubricant is selected from at least one of glycerin and stearic acid, preferably stearic acid; the additives include glass fiber, pulp cotton and ammonia water, preferably including 12-16 parts of glass fiber, 8-10 parts of pulp cotton and 20-22 parts of ammonia water.

[0011] In step S1, a mixer is used for mixing, with a cylinder speed of 8-12 r / min and a mixing time of 25-35 min, so as to make the powder more uniformly mixed.

[0012] In step S2, the dispersant, binder, lubricant, additive, and water can be added in stages and mixed, and the pH value can be adjusted in stages. Specifically, the dispersant, binder, lubricant, additive, and water are added in two stages and mixed, and the pH value is adjusted in two stages. During the first mixing, the mixing speed is 10-15 r / min, the temperature is 85-95 ℃, the water content is 30-50%, and the time is 25-35 min. The pH value can be adjusted to 7.0-7.9 during the first mixing. During the second mixing, the mixing speed is 18-22 r / min, the water content is 20-30%, and the time is 40-50 min. The pH value can be adjusted to 8.1-8.7 during the second mixing. That is, the final pH value of the mud is controlled to be 8.1-8.7.

[0013] In step S3, a ply mill with a 0.1-1 mm steel mesh can be used for filtration and ply milling. The filtration temperature is 25-40 ℃, the rotation speed is 60-100 r / min, the filtration is performed 1-3 times, and the filtration time for each filtration is 50-70 min. The vacuum degree during ply milling is -0.05 MPa to -0.2 MPa, the temperature is 30-45 ℃, the ply milling is performed 2-3 times, and the ply milling time for each ply milling is 15-20 min. The above method helps to remove air bubbles inside the ply, thereby obtaining a dense and uniform plastic ply.

[0014] During extrusion, the extruder barrel temperature is 40-60 ℃, the die head temperature is 35-50 ℃, the extrusion pressure is 10-20MPa, and the extrusion speed is 0.5-1.5 m / min; the thickness of the flat preform is 0.8-2.0 mm, the width is 500-700 mm, and the moisture content is 15-25%.

[0015] In step S4, the rolling temperature is 30-45 ℃, the corrugated roller speed is 0.3-1.0 m / min, and the rolling pressure is 5-12 MPa; the size of the protrusion is 0.1-0.3 mm, the wave height of the corrugation is 3-8 mm, and the wave width (i.e., wave pitch) is 10-20 mm; the cross-sectional shape of the protrusion is not limited to a circle, but can also be a triangle, square, rectangle, wave, etc., preferably a circle.

[0016] The cutting angle can be 20°-90°, for example 45°-60°; after cutting, remove edge burrs and defects to obtain a regular corrugated blank.

[0017] More specifically, the surface (front) of the corrugated blank has multiple continuous corrugations, the corrugations are inclined, the top surface of the corrugations has a roll-pressed convex surface, and there are roll-pressed concave surfaces between adjacent corrugations. At least one row of protrusions is provided on the two sides of the corrugations; wherein, the angle of the corrugations is 20°-90°, for example 45°-60°, and the distance between adjacent protrusions is 2-5 cm.

[0018] In step S5, drying includes: first drying at 60-80 ℃ for 22-26 h, then drying at 90-110 ℃ for 10-15 h, and then drying at 55-65 ℃ for 65-70 h, while controlling the moisture content of the dried corrugated blank to ≤2%. Preferably, drying includes: first drying at 60-80 ℃ for 24-26 h, then drying at 100-108 ℃ for 10-12 h, and then drying at 55-65 ℃ for 65-70 h. This gradient drying method helps to avoid cracking and deformation during subsequent sintering.

[0019] Calcination includes: first, heating from room temperature to 100-200 °C at a rate of 1-3 °C / min and holding for 1-3 h to completely remove moisture (including surface and internal moisture) from the catalyst; then, heating to 200-400 °C at a rate of 2-5 °C / min and holding for 2-3 h to completely remove the binder and additives such as binders; then, heating to 450-550 °C at a rate of 3-6 °C / min and holding for 4-6 h to release and bind the active ingredients. Preferably, calcination includes: first, heating from room temperature to 200 °C at a rate of 2 °C / min and holding for 2 h; then, heating to 400 °C at a rate of 3 °C / min and holding for 3 h; then, heating to 480-520 °C at a rate of 4 °C / min and holding for 5 h. The gradient calcination method described above helps to prevent problems such as catalyst cracking, bending, and insufficient mechanical strength.

[0020] The present invention also provides an SCR catalyst, which is prepared according to the above preparation method.

[0021] The present invention also provides the application of the above-mentioned SCR catalyst in flue gas denitrification.

[0022] In application, SCR catalysts can be stacked in a parallel, staggered manner, that is, multiple SCR catalysts are stacked one on top of the other. When stacking, the corrugations of adjacent SCR catalysts are opposite in direction, and the peaks of the upper SCR catalyst correspond to the troughs of the lower SCR catalyst to form a flue gas flow channel (at this time, the troughs of the upper SCR catalyst are adjacent to the peaks of the lower SCR catalyst, see...). Figure 1 , Figure 2 ).

[0023] The implementation of this invention has at least the following advantages: 1. This invention uses a reasonable raw material composition and ratio, adds effective auxiliary ingredients, and optimizes the dosage of active components, which greatly saves raw material costs and enables the active components and auxiliary agents to work synergistically, significantly improving the SCR denitrification efficiency and the ability to eliminate yellow smoke.

[0024] 2. This invention adopts a process route of extruding flat blanks and forming with raised corrugated rolls, which realizes continuous and large-scale production of catalysts with a yield of 100% and a production efficiency that is 3-5 times higher than that of compression molding and extrusion molding. At the same time, through the integrated process of extrusion, rolling and calcination, the components are uniformly dispersed in the carrier, avoiding the shedding of the active layer and significantly improving the stability and service life of the catalyst.

[0025] 3. This invention employs a unique configuration design to precisely control the corrugation size, resulting in a regular corrugated structure with high mechanical strength, making it less prone to cracking and deformation. Furthermore, through the oblique cutting and cross-stacking arrangement, the internal corrugated structure of the catalyst presents a cross-parallel arrangement with the same angle. This unique cross structure can achieve the purpose of turbulence and further affect the mass transfer coefficient. In addition, the unique protrusion design on the catalyst enhances this phenomenon, which on the one hand increases the residence time of flue gas after passing through the catalyst, and on the other hand increases the contact area of ​​the catalyst, greatly improving the denitrification efficiency.

[0026] 4. This invention develops an SCR catalyst that is unsupported, has low raw material cost, high denitrification efficiency, and controllable volume. While improving denitrification efficiency, it can reduce the volume of catalyst used. Under the same denitrification efficiency, the catalyst has a smaller volume and is more suitable for some new denitrification systems, such as small chemical reactors, small mobile catalytic devices, and ship exhaust gas denitrification reactors. It can replace traditional vanadium-tungsten honeycomb and corrugated plate catalysts, greatly saving raw material costs. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a front view of the stacked SCR catalyst of the present invention.

[0029] Figure 2 This is a schematic diagram of the stacked structure of the SCR catalyst of the present invention. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1 The preparation method of the SCR catalyst in this embodiment includes the following steps: 1. Ingredient mixing: 100 parts of carrier powder (TiO2), 3 parts of active component (V2O5), and 3 parts of additives (1.5 parts of MoO3 and 1.5 parts of MnO2) were placed into a mixer, and the cylinder speed was controlled at 10 r / min. The mixture was mixed for 30 min to obtain a mixed powder.

[0034] Add 1 part dispersant (polyethylene glycol), 2 parts binder (1 part carboxymethyl cellulose, 1 part polyvinyl alcohol), 1 part lubricant (stearic acid), 45 parts additives (15 parts glass fiber, 10 parts pulp cotton, 20 parts ammonia water), and 20 parts deionized water to the above mixed powder in two batches. For the first addition, control the cylinder speed at 12 r / min, the temperature at 90 ℃, and the water content at 30%. Add a small amount of ammonia water to adjust the pH value to 7.2 and continue stirring and mixing for 30 min. For the second addition, control the cylinder speed at 20 r / min, the water content at 22%, add a small amount of ammonia water to adjust the pH value to 8.1, and continue stirring and mixing for 45 min to obtain the mud.

[0035] 2. Filtering and refining the mud: The above-mentioned mud was placed into a mud refining machine with a 1 mm steel mesh for filtration and refining. The filtration temperature was 30 ℃ and the rotation speed was 80 r / min. The filtration was carried out twice, and the filtration time was 60 min each time. The vacuum degree during mud refining was -0.085 MPa and the temperature was 35 ℃. The mud was refining twice, and the refining time was 18 min each time, to obtain dense plastic mud.

[0036] 3. Extrusion of flat preform: The above-mentioned dense plastic clay material was fed into a twin-screw extruder, and the barrel temperature was controlled at 50 ℃, the die head temperature at 40 ℃, the extrusion pressure at 15 MPa, and the extrusion speed at 1.0 m / min to obtain a flat preform with a thickness of 1.2 mm, a width of 520 mm, and a moisture content of 20%.

[0037] 4. Corrugated roll forming: The above-mentioned flat blank is fed into a corrugated roll press, and the roll pressing temperature is controlled at 38 ℃, the corrugated roll speed is 0.6 m / min, the roll pressing pressure is 8 MPa, the cross-sectional shape of the protrusion is circular, the radius of the protrusion is 0.2 mm, the distance between adjacent protrusions is 2 mm, and it is pressed into a corrugated blank with a wave height of 5 mm and a wave pitch of 12 mm.

[0038] 5. Trimming and finishing: The corrugated blank is cut at a 45° angle into 480 mm long blanks and the edge burrs are removed.

[0039] 6. Drying process: The trimmed corrugated blank was placed in a drying oven and dried at 60 ℃ for 24 h. Then the temperature was raised to 100 ℃ and dried for another 10 h. Finally, the temperature was lowered to 55 ℃ and dried for another 70 h. The moisture content of the dried corrugated blank was 1.8%.

[0040] 7. High-temperature roasting: The dried corrugated preform was fed into a calcining furnace. The temperature was first increased from room temperature to 200℃ at a rate of 2℃ / min and held for 2 h. Then, the temperature was increased to 400℃ at a rate of 3℃ / min and held for 3 h. Finally, the temperature was increased to 500℃ at a rate of 4℃ / min and held for 5 h. The preform was then allowed to cool naturally to room temperature to obtain the SCR catalyst (based on the support, the active components and additives content are: V2O5 3%, MoO3 1.5%, MnO2 1.5%).

[0041] Example 2 The preparation method of the SCR catalyst in this embodiment includes the following steps: 1. Ingredient mixing: 100 parts of carrier powder (TiO2), 2 parts of active component (V2O5), and 3 parts of additives (1.5 parts of MoO3 and 1.5 parts of CeO2) were placed into a mixer, and the cylinder speed was controlled at 10 r / min. The mixture was mixed for 30 min to obtain a mixed powder.

[0042] Add 0.5 parts dispersant (sodium tripolyphosphate), 2 parts binder (carboxymethyl cellulose), 2 parts lubricant (stearic acid), 44 parts additives (16 parts glass fiber, 8 parts pulp cotton, 20 parts ammonia water), and 18 parts deionized water to the above mixed powder in two batches. During the first addition, control the cylinder speed at 10 r / min, the temperature at 85 ℃, and the water content at 42%. Add a small amount of ammonia water to adjust the pH value to 7.5 and continue stirring and mixing for 35 min. During the second addition, control the cylinder speed at 18 r / min, the water content at 22%, add a small amount of ammonia water to adjust the pH value to 8.2, and continue stirring and mixing for 50 min to obtain the mud.

[0043] 2. Filtering and refining the mud: The above-mentioned mud was placed into a mud refining machine with a 1 mm steel mesh for filtration and refining. The filtration temperature was 30 ℃ and the rotation speed was 100 r / min. The filtration was carried out twice, and the filtration time was 60 min each time. The vacuum degree during mud refining was -0.085 MPa and the temperature was 35 ℃. The mud was refining twice, and the refining time was 18 min each time, to obtain dense plastic mud.

[0044] 3. Extrusion of flat preform: The above-mentioned plastic clay material was fed into a twin-screw extruder, and the barrel temperature was controlled at 50 ℃, the die head temperature at 40 ℃, the extrusion pressure at 16 MPa, and the extrusion speed at 1.0 m / min to obtain a flat preform with a thickness of 2 mm, a width of 520 mm, and a moisture content of 20%.

[0045] 4. Corrugated roll forming: The above-mentioned flat blank is fed into a corrugated roll press, and the roll pressing temperature is controlled at 38 ℃, the corrugated roll speed is 0.6 m / min, the roll pressing pressure is 8 MPa, the convex point radius is 0.2 mm, the distance between adjacent convex points is 2 mm, and a corrugated blank with a wave height of 4 mm and a wave pitch of 10 mm is formed.

[0046] 5. Trimming and finishing: The above-mentioned corrugated blank was cut into 480 mm long blanks at a 50° angle and the edge burrs were removed.

[0047] 6. Drying process: The trimmed and edged corrugated blank was sent into a drying oven and dried at 70 ℃ for 24 h. Then the temperature was raised to 100 ℃ and dried for another 11 h. Finally, the temperature was lowered to 65 ℃ and dried for another 65 h. The moisture content of the dried corrugated blank was 1.8%.

[0048] 7. High-temperature roasting: The dried corrugated preform was fed into a calcining furnace and heated from room temperature to 200℃ at a heating rate of 2℃ / min, and held for 2 hours. Then, the temperature was increased to 400℃ at a heating rate of 3℃ / min and held for 3 hours. Finally, the temperature was increased to 480℃ at a heating rate of 4℃ / min and held for 5 hours. The preform was then allowed to cool naturally to room temperature to obtain the SCR catalyst.

[0049] Example 3 The preparation method of the SCR catalyst in this embodiment includes the following steps: 1. Ingredient mixing: 100 parts of carrier powder (TiO2), 3 parts of active component (V2O5), and 1.5 parts of additives (1 part MoO3 and 0.5 parts CeO2) were placed into a mixer. The rotation speed of the mixing cylinder was controlled at 10 r / min, and the mixture was mixed for 30 min to obtain a mixed powder.

[0050] Add 0.5 parts dispersant (sodium tripolyphosphate), 2 parts binder (carboxymethyl cellulose), 2 parts lubricant (stearic acid), 45 parts additives (14 parts glass fiber, 9 parts pulp cotton, 22 parts ammonia water), and 15 parts deionized water to the above mixed powder in two batches. For the first addition, control the cylinder speed at 12 r / min, the temperature at 90 ℃, and the water content at 37%. Add a small amount of ammonia water to adjust the pH value to 7.3 and continue stirring and mixing for 30 min. For the second addition, control the cylinder speed at 20 r / min, the water content at 21%, add a small amount of ammonia water to adjust the pH value to 8.2, and continue stirring and mixing for 45 min to obtain the mud.

[0051] 2. Filtering and kneading: The above-mentioned mud was placed into a mud refining machine with a 1 mm steel mesh for filtration and refining. The filtration temperature was 30 ℃ and the rotation speed was 80 r / min. The filtration was carried out twice, and the filtration time was 60 min each time. The vacuum degree during mud refining was -0.085 MPa and the temperature was 35 ℃. The mud was refining three times, and the refining time was 18 min each time, to obtain dense plastic mud.

[0052] 3. Extrusion of flat preform: The above-mentioned plastic clay material was fed into a twin-screw extruder, and the barrel temperature was controlled at 50 ℃, the die head temperature at 40 ℃, the extrusion pressure at 16 MPa, and the extrusion speed at 1.0 m / min to obtain a flat preform with a thickness of 2.5 mm, a width of 520 mm, and a moisture content of 20%.

[0053] 4. Corrugated roll forming: The above-mentioned flat blank is fed into a corrugated roll press, and the roll pressing temperature is controlled at 38 ℃, the corrugated roll speed is 0.6 m / min, the roll pressing pressure is 8 MPa, the convex point radius is 0.2 mm, the distance between adjacent convex points is 2.2 mm, and it is pressed into a corrugated blank with a wave height of 3 mm and a wave pitch of 10 mm.

[0054] 5. Trimming and finishing: The corrugated blank is cut at a 55° angle into 480 mm long blanks and the edge burrs are removed.

[0055] 6. Drying process: The trimmed and edged corrugated blank was sent into a drying oven and dried at 78 ℃ for 26 h. Then the temperature was raised to 105 ℃ and dried for another 12 h. Finally, the temperature was lowered to 58 ℃ and dried for another 66 h. The moisture content of the dried corrugated blank was 1.8%.

[0056] 7. High-temperature roasting: The dried corrugated preform was fed into a calcining furnace and heated from room temperature to 200°C at a heating rate of 2°C / min, and held for 2 hours. Then, the temperature was increased to 400°C at a heating rate of 3°C / min and held for 3 hours. Finally, the temperature was increased to 510°C at a heating rate of 4°C / min and held for 5 hours. The preform was then allowed to cool naturally to room temperature to obtain the SCR catalyst.

[0057] Example 4 The preparation method of the SCR catalyst in this embodiment includes the following steps: 1. Ingredient mixing: Mix 100 parts carrier powder (TiO2), 2 parts active component (V2O5), and 2 parts additives (1 part MoO3, 0.5 parts CeO2). 2、 0.5 parts of MnO2 were placed into a mixer, the cylinder speed was controlled at 10 r / min, and the mixture was mixed for 30 min to obtain a mixed powder.

[0058] The above-mentioned mixed powder was added in two batches: 1 part dispersant (0.5 parts polyethylene oxide, 0.5 parts polyethylene glycol), 1.5 parts binder (carboxymethyl cellulose), 2 parts lubricant (stearic acid), 44 parts additives (12 parts glass fiber, 10 parts pulp cotton, 22 parts ammonia water), and 18 parts deionized water. During the first addition, the mixing cylinder speed was controlled at 12 r / min, the temperature at 90 ℃, and the water content at 30%. A small amount of ammonia water was added to adjust the pH value to 7.3, and the mixture was stirred continuously for 30 min. During the second addition, the mixing cylinder speed was controlled at 20 r / min, the water content at 21%, and a small amount of ammonia water was added to adjust the pH value to 8.2. The mixture was stirred continuously for 45 min to obtain the mud.

[0059] 2. Filtering and kneading: The above-mentioned mud was placed into a mud refining machine with a 1 mm steel mesh for filtration and refining. The filtration temperature was 30 ℃ and the rotation speed was 80 r / min. The filtration was carried out twice, and the filtration time was 60 min each time. The vacuum degree during mud refining was -0.085 MPa and the temperature was 35 ℃. The mud was refining three times, and the refining time was 18 min each time, to obtain dense plastic mud.

[0060] 3. Extrusion of flat preform: The above-mentioned plastic clay material was fed into a twin-screw extruder, and the barrel temperature was controlled at 50 ℃, the die head temperature at 40 ℃, the extrusion pressure at 16 MPa, and the extrusion speed at 1.0 m / min to obtain a flat preform with a thickness of 3 mm, a width of 520 mm, and a moisture content of 20%.

[0061] 4. Corrugated roll forming: The above-mentioned flat blank is fed into a corrugated roll press, and the roll pressing temperature is controlled at 38 ℃, the corrugated roll speed is 0.6 m / min, the roll pressing pressure is 8 MPa, the convex point radius is 0.2 mm, the distance between adjacent convex points is 2.1 mm, and it is pressed into a corrugated blank with a wave height of 3.5 mm and a wave pitch of 10 mm.

[0062] 5. Trimming and finishing: The corrugated blank is cut at a 60° angle into 480 mm long blanks and the edge burrs are removed.

[0063] 6. Drying process: The trimmed and edged corrugated blank was sent into a drying oven and dried at 80 ℃ for 24 h. Then the temperature was raised to 108 ℃ and dried for another 12 h. Finally, the temperature was lowered to 56 ℃ and dried for another 65 h. The moisture content of the dried corrugated blank was 1.8%.

[0064] 7. High-temperature roasting: The dried corrugated preform was fed into a calcining furnace and heated from room temperature to 200℃ at a heating rate of 2℃ / min, and held for 2 hours. Then, the temperature was increased to 400℃ at a heating rate of 3℃ / min and held for 3 hours. Finally, the temperature was increased to 520℃ at a heating rate of 4℃ / min and held for 5 hours. The preform was then allowed to cool naturally to room temperature to obtain the SCR catalyst.

[0065] Compare with Example 1 This comparative example uses an existing planar catalyst as a control, and the preparation method is as follows: Using a stainless steel mesh as a support frame, the raw materials are fully mixed to form a plastic mud, which is then uniformly coated onto the surface of the mesh by roller pressing. After being dried and shaped in sections at low temperature, it is then pleated and pressed, cut and stacked according to specifications, and finally sent to a high-temperature kiln to complete the calcination and activation to produce a flat catalyst (the active components and additives are the same as in Example 1, namely: V2O5 3%, MoO3 1.5%, MnO2 1.5%).

[0066] Compare with Example 2 This comparative example uses an existing honeycomb catalyst as a control, and the preparation method is as follows: The raw materials are thoroughly mixed in a mixer. The uniformly mixed mud is filtered to remove the remaining impurities. After aging for one day, it is extruded into a wet blank using an extruder. The wet blank is dried and calcined to produce a honeycomb catalyst (the active components and additives are the same as in Example 1, i.e.: V2O5 3%, MoO3 1.5%, MnO2 1.5%).

[0067] Compare with Example 3 This comparative example uses an existing corrugated plate catalyst as a control, and the preparation method is as follows: High-strength glass fiber cloth was used as the substrate. First, the glass fiber cloth was impregnated with titanium dioxide slurry and dried to form a regular corrugated structure using a hot pressing device. Then, it was calcined at a low temperature. Subsequently, the active components and additives were loaded using a solution impregnation method. After secondary drying and medium-temperature calcination, a corrugated plate catalyst was prepared (the content of active components and additives was the same as in Example 1, namely: V2O5 3%, MoO3 1.5%, MnO2 1.5%).

[0068] Compare with Example 4 This comparative example uses existing commercially available honeycomb catalysts as a control (based on the support, the active component and additive content are: V2O5 2%, WO3 3%).

[0069] Experimental Example 1 Combination Figure 1 , Figure 2 As shown, multiple SCR catalysts prepared in Examples 1-4 are stacked one on top of the other. When stacking, the ripple directions of adjacent SCR catalysts are opposite, and the peaks of the upper SCR catalyst are set to correspond to the troughs of the lower SCR catalyst to form a flue gas flow channel.

[0070] The denitrification efficiency was tested using an industrial flue gas simulation method, with the following flue gas conditions: NOx concentration of 300 mg / m³. 3 The reaction temperature was 345 °C; the catalyst volume was 150 mm × 150 mm × 450 mm; and the reaction time was 30 min.

[0071] The mechanical strength, denitrification efficiency after aging, and other performance tests were conducted in accordance with the following standards: DL / T 1286-2021 "Technical Specification for Testing of Flue Gas Denitrification Catalysts in Thermal Power Plants"; VGB "Guideline for the Testing of DeNOx Catalyst"; EPRI "Protocol for Laboratory Testing SCR Catalyst Samples"; GB / T 31587-2015 "Honeycomb Flue Gas Denitrification Catalysts"; GB / T 31584-2015 "Plate-plate Flue Gas Denitrification Catalysts"; and GB / T 39703-2020 "Technical Specification for Testing Corrugated Plate Denitrification Catalysts". The results are shown in Table 1.

[0072] Table 1

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an SCR catalyst, characterized in that, Includes the following steps: S1: Mix the carrier, active component and additives evenly to obtain a mixed powder; S2: Add dispersant, binder, lubricant, additive and water to the mixed powder, stir and mix, adjust the pH value to obtain mud; S3: After filtering and refining the clay, the clay is extruded to obtain a flat blank. S4: The flat blank is fed into the corrugated roller press and rolled into a corrugated structure with raised dots. After cutting, the corrugated blank is obtained. S5: The corrugated preform is dried and calcined to obtain the SCR catalyst.

2. The preparation method according to claim 1, characterized in that, The mass fractions of each raw material are as follows: 100 parts carrier, 2-4 parts active ingredient, 1-5 parts additive, 0.5-2 parts dispersant, 1-3 parts binder, 0.5-2 parts lubricant, 20-50 parts additive, and 10-30 parts water.

3. The preparation method according to claim 1, characterized in that, The carrier is TiO2; the active component is V2O5; the auxiliary agent is selected from at least one of CeO2, MnO2, MoO3 and WO3; the dispersant is selected from at least one of sodium tripolyphosphate, polyethylene glycol and polyethylene oxide; the binder is selected from at least one of carboxymethyl cellulose and polyvinyl alcohol; the lubricant is selected from at least one of glycerin and stearic acid; the additives include glass fiber, pulp cotton and ammonia.

4. The preparation method according to claim 1, characterized in that, The filtration temperature is 25-40 ℃, the rotation speed is 60-100 r / min, the filtration is repeated 1-3 times, and the filtration time is 50-70 min each time; the vacuum degree during mud refining is -0.05MPa to -0.2 MPa, the temperature is 30-45 ℃, the mud refining is repeated 2-3 times, and the refining time is 15-20 min each time.

5. The preparation method according to claim 1, characterized in that, During extrusion, the extruder barrel temperature is 40-60 ℃, the die head temperature is 35-50 ℃, the extrusion pressure is 10-20 MPa, and the extrusion speed is 0.5-1.5 m / min; the thickness of the flat preform is 0.8-2.0 mm, and the width is 500-700 mm.

6. The preparation method according to claim 1, characterized in that, The rolling temperature is 30-45 ℃, the corrugated roll speed is 0.3-1.0 m / min, and the rolling pressure is 5-12 MPa; the convex size of the corrugated blank is 0.1-0.3 mm, the wave height is 3-8 mm, and the wave width is 10-20 mm.

7. The preparation method according to claim 1, characterized in that, The drying process includes: first drying at 60-80 ℃ for 22-26 h, then drying at 90-110 ℃ for 10-15 h, and then drying at 55-65 ℃ for 65-70 h, while controlling the moisture content of the dried corrugated blank to be ≤2%.

8. The preparation method according to claim 1, characterized in that, Roasting includes: First, raise the temperature from room temperature to 100-200 ℃ at a heating rate of 1-3 ℃ / min and hold for 1-3 h; then, continue to raise the temperature to 200-400 ℃ at a heating rate of 2-5 ℃ / min and hold for 2-3 h; then, continue to raise the temperature to 450-550 ℃ at a heating rate of 3-6 ℃ / min and hold for 4-6 h.

9. An SCR catalyst, characterized in that, Prepared according to the preparation method according to any one of claims 1-8.

10. The application of the SCR catalyst according to claim 9 in flue gas denitrification.

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