Wear-resistant honeycomb SCR denitration catalyst and preparation method thereof
By combining anatase-type titanium dioxide with zirconium dioxide and silicon-aluminum composites, a high-strength honeycomb SCR denitrification catalyst was prepared, which solved the problem of easy damage of existing catalysts under high dust flue gas, significantly improved compressive and wear resistance and extended service life.
Patent Information
- Application Number
- CN202311599672.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-28
- Publication Date
- 2025-05-30
AI Technical Summary
Existing honeycomb SCR denitrification catalysts are prone to physical damage under the flue gas with high dust content, such as rupture and collapse, resulting in insufficient wear resistance and short service life.
By combining anatase-type titanium dioxide with zirconium dioxide and silicon-aluminum composites to form a high-strength catalyst matrix, the compressive and wear resistance of the catalyst is enhanced. The specific method includes dry mixing titanium dioxide, organic binder, silicon-aluminum composite, anti-cracking agent with the silica precursor, and adding active solvents, alkaline solutions, etc., and preparing a wear-resistant honeycomb SCR denitrification catalyst through steps such as staleness, molding, drying and calcination.
The compressive and wear resistance of the catalyst is significantly improved, the service life of the catalyst is extended, and the wear rate is reduced from 0.079%/kg to 0.009%/kg.
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Figure CN120054462A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of SCR (selective catalytic reduction) denitration catalysts, and particularly relates to a wear-resistant honeycomb SCR denitration catalyst and a preparation method thereof. Background Art
[0002] Most of the flue gas discharged from fixed-source facilities in China has a high dust content, such as coal-fired power plants, cement kilns, etc. The wear of the catalyst by dust is mainly reflected in two positions of the catalyst. The wear occurring at the top of the catalyst is mainly caused by cutting force, and the wear occurring on the inner wall of the catalyst pores is mainly caused by abrasion. The wear rate of the catalyst is closely related to the hardness, concentration, particle size of the dust, and the flue gas flow rate. The greater the dust hardness, the larger the particle size, the higher the mass concentration, and the faster the flue gas flow rate, the faster the wear of the catalyst. Catalyst wear will damage the physical structure of the catalyst and cannot be regenerated, making wear an important factor in catalyst consumption.
[0003] Currently, honeycomb catalysts mainly adopt the method of end-face hardening to improve the anti-wear performance of the catalyst, and generally use ammonium metavanadate, ammonium metatungstate, aluminum dihydrogen phosphate, etc. as the end-face hardening solution. However, for flue gas with a high dust content, the wear of the catalyst end-face can generally only be alleviated through end-face hardening, and the problem of catalyst wear cannot be completely solved. Especially in the case of catalyst pore blockage and uneven flow field distribution, under the erosion of high-dust-content flue gas, the honeycomb catalyst will be physically damaged such as cracking and collapse due to insufficient wear resistance, resulting in catalyst loss. Summary of the Invention
[0004] Aiming at the problem of poor wear resistance of the above-mentioned honeycomb SCR denitration catalyst, the present invention provides a wear-resistant honeycomb SCR denitration catalyst and a preparation method thereof. By combining anatase titanium dioxide with zirconium dioxide and a silica-alumina composite to form a high-strength catalyst matrix, the present invention greatly improves the overall wear resistance of the catalyst and prolongs the service life of the catalyst.
[0005] In the first aspect, the present invention provides a wear-resistant honeycomb SCR denitration catalyst. The chemical composition of the wear-resistant honeycomb SCR denitration catalyst includes: 70-90 parts by mass of titanium dioxide, 0.4-5 parts by mass of vanadium pentoxide, 1-5 parts by mass of tungsten trioxide, 0.5-3 parts by mass of molybdenum trioxide, 1-10 parts by mass of zirconium dioxide, 3-10 parts by mass of silicon dioxide, and 3-15 parts by mass of a silica-alumina composite.
[0006] Preferably, the titanium dioxide is anatase titanium dioxide with a specific surface area of 120-300 m 2 / g; wherein, the D90 of the titanium dioxide particle size < 5 μm, D50 < 1 μm, and the average grain size is 5-15 nm; The silicon-aluminum composite is a porous silicon-aluminum molecular sieve with strong acidity, a low-crystallinity silicon-aluminum oxide, or an amorphous strong-acid silicon-aluminum oxide, preferably at least one of ITQ-1, ITQ-7, ITQ-10, or an aluminum-containing silicon molecular sieve.
[0007] In a second aspect, the present invention provides a method for preparing the above-mentioned wear-resistant honeycomb SCR denitration catalyst, and the preparation method includes the following steps: (1) Dry-mix titanium dioxide, an organic binder, a silicon-aluminum composite, an anti-cracking agent, and a silica precursor. Meanwhile, add an active solvent, an alkaline solution, an ammonium metavanadate solution, an ammonium metatungstate solution, an ammonium molybdate solution, a zirconia sol, an extrusion aid, a pore-forming agent, and a water retention agent to the dry-mixed materials, stir for 1 to 1.5 hours to mix evenly, and then adjust the pH to obtain a mud material; (2) Age and mold the mud material in sequence to obtain a green body; (3) Dry and calcine the green body to obtain the wear-resistant honeycomb SCR denitration catalyst.
[0008] Preferably, the organic binder is selected from at least one of ammonium carboxymethyl cellulose, hydroxypropyl cellulose, and polyethylene oxide; among them, the molecular weight of ammonium carboxymethyl cellulose is 2 million to 3 million, the molecular weight of hydroxypropyl cellulose is 4 million to 6 million, and the molecular weight of polyethylene oxide is 1 million to 3 million; The anti-cracking agent is selected from hydrophilic PP short fibers and wood fiber wool; among them, the diameter of the PP fiber is 15 to 30 μm; The silica precursor is selected from glass fiber, silica aerogel, or silica sol.
[0009] Preferably, the mass ratio of titanium dioxide, the organic binder, the silicon-aluminum composite, the anti-cracking agent, and the silica precursor is 100:0.5 to 6:5.9 to 28:0.5 to 2:3.5 to 12, preferably 100:0.5 to 3:6 to 21:0.5 to 0.9:3.5 to 9.
[0010] Preferably, the active solution is deionized water, and the alkaline solution is ammonia water; The ammonium metavanadate is dissolved in a 15 to 20% monoethanolamine solution to form a solution with a concentration of 5 to 30%, preferably 5 to 15%; the concentration of the ammonium metatungstate solution is 16 to 60%, preferably 20 to 60%; the concentration of the ammonium molybdate solution is 10 to 20%; The zirconia content in the zirconia sol is 10 to 15%; The extrusion aid is at least one of oleic acid, stearic acid, a fatty acid preparation containing a non-ionic emulsifier, and a high-polymerization-degree polysaccharide; the pore-forming agent is lactic acid; the water retention agent is ethylene glycol, propylene glycol, or glycerol.
[0011] Preferably, the mass ratio of the active solvent, alkaline solution, ammonium metavanadate solution, ammonium metatungstate solution, ammonium molybdate solution, zirconia sol, extrusion aid, pore former and water retention agent is 100:40-60:125:150:125:110-240:5-25:5-10:5-11, preferably 100:40-60:125:150:125:110-140:5-25:5-10:5-11; The ratio of the total mass of the dry-mixed materials to the total mass of the active solvent, alkaline solution, ammonium metavanadate solution, ammonium metatungstate solution, ammonium molybdate solution, zirconia sol, extrusion aid, pore former and water retention agent is 100:40-70, preferably 100:60-70.
[0012] Preferably, the pH of the mud is adjusted with ammonia water or organic base; wherein, the organic base is methylamine ammonia, monoethanolamine, diethanolamine; The moisture content of the mud is 25-27%, and the pH is 8.0-10.
[0013] Preferably, the aging is carried out in an aging bag, and it is aged in a sealed and light-shielded manner at room temperature for 18-36 hours.
[0014] Preferably, the calcination process is as follows: using a mesh belt furnace to raise the temperature from 30°C to the highest calcination temperature of 500-680°C in a programmed manner, controlling the mesh belt speed to be 1.5-3 m / h, and the calcination time to be 17-35 hours, with the highest calcination temperature being kept for 4-8 hours.
[0015] Beneficial Effects In the preparation of the existing honeycomb denitration catalyst, the present invention adds a structure enhancer zirconia and a silica-alumina composite. The added zirconia and silica-alumina composite form a Ti-O-Zr-O-Ti structure and a Ti-O-Si-O-Ti structure with titanium dioxide, enhancing the bonding strength between titanium dioxide particles in the catalyst. At the same time, zirconia and the silica-alumina composite have good compressive and abrasion resistance properties. Therefore, the honeycomb denitration catalyst of the present invention has excellent compressive and abrasion resistance properties. Description of the Drawings
[0016] Figure 1 It is a scanning electron micrograph of the catalyst sample prepared in Example 3; Figure 2 It is a scanning electron micrograph of the catalyst sample prepared in Comparative Example 1. Detailed Embodiments
[0017] The present invention will be further described through embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, rather than limiting the present invention.
[0018] First, the present invention provides a wear-resistant honeycomb SCR denitration catalyst. The chemical composition of the wear-resistant honeycomb SCR denitration catalyst may include: 70-90 parts by mass of titanium dioxide, 0.4-5 parts by mass of vanadium pentoxide, 1-5 parts by mass of tungsten trioxide, 0.5-3 parts by mass of molybdenum trioxide, 1-10 parts by mass of zirconium dioxide, 3-10 parts by mass of silicon dioxide, and 3-15 parts by mass of a silicon-aluminum composite.
[0019] The wear-resistant honeycomb SCR denitration catalyst provided by the present invention uses a composite formed by three components of titanium dioxide, zirconium dioxide and a silicon-aluminum composite as a carrier. Among them, zirconium dioxide and the silicon-aluminum composite respectively form a Ti-O-Zr-O-Ti structure and a Ti-O-Si-O-Ti structure with titanium dioxide, greatly enhancing the bonding strength between titanium dioxide particles in the catalyst; at the same time, zirconium dioxide and the silicon-aluminum composite also have good compressive and wear-resistant properties. Therefore, compared with the existing honeycomb denitration catalyst, the honeycomb denitration catalyst provided by the present invention has excellent compressive and wear-resistant properties and denitration performance, and the wear rate is reduced from 0.079% / kg to 0.009% / kg, which can significantly extend the service life of the catalyst.
[0020] In some embodiments, the titanium dioxide may be anatase titanium dioxide with a specific surface area of 120-300 m 2 / g, serving as a catalyst carrier; wherein, the D90 of the particle size of the titanium dioxide is <5 μm, the D50 is <1 μm, and the average grain size is 5-15 nm.
[0021] In some embodiments, the vanadium pentoxide can play a role in catalyzing the denitration reaction and exists as an active component. If the content of vanadium pentoxide is too high, it will cause too high SO 2 oxidation rate; if the content is too low, it will cause too low denitration activity.
[0022] In some embodiments, the tungsten trioxide can play a role in improving the acidity and stability of the catalyst and exists as a catalytic assistant. If the content is too high, it will lead to high production costs; if the content is too low, it will lead to a decrease in denitration activity and sulfur resistance stability.
[0023] In some embodiments, the molybdenum trioxide can play a role in improving the denitration reaction activity under low-temperature conditions and exists as a catalyst assistant. If the content is too high, it will lead to high production costs; if the content is too low, it will lead to low denitration activity at low temperature.
[0024] If the content of zirconium dioxide is too high, it will lead to a decrease in the denitration activity of the catalyst; if the content is too low, it will lead to a decrease in the strength of the catalyst.
[0025] In some embodiments, the silica can play a role in improving the strength of the catalyst green body. If the content is too high, the denitrification activity will be reduced; if the content is too low, the strength of the green body will be low.
[0026] In some embodiments, the silica-aluminum composite can be a porous silica-aluminum molecular sieve with strong acidity, a low-crystallinity silica-aluminum oxide or an amorphous strong-acid silica-aluminum oxide; preferably at least one of ITQ-1, ITQ-7, ITQ-10 or an aluminosilicate molecular sieve. If the content of the silica-aluminum composite is too high, the vanadium activity will be low; if the content is too low, the strength of the green body will be reduced.
[0027] The honeycomb SCR denitration catalyst provided by the present invention has excellent compressive and abrasion resistance performance, and can significantly extend the service life of the catalyst. In some embodiments, the axial compressive strength of the wear-resistant honeycomb SCR denitration catalyst is 5.1-5.8 MPa, the radial compressive strength is 1.9-2.4 MPa, and the wear rate is 0.009-0.026% / kg.
[0028] Hereinafter, an exemplary preparation method of the wear-resistant honeycomb SCR denitration catalyst provided by the present invention is described. The preparation method may include the following steps: dry-mix titanium dioxide, an organic binder, a silica-aluminum composite, an anti-cracking agent and a silica precursor, and at the same time add an active solvent, an alkaline solution, an ammonium metavanadate solution, an ammonium metatungstate solution, an ammonium molybdate solution, a zirconia sol, an extrusion aid, a pore-forming agent and a water retention agent to the dry-mixed materials, stir for 1-1.5 hours to mix evenly, and then adjust the pH to obtain a mud; then, subject the mud to aging and molding in sequence to obtain a green body; then, obtain the wear-resistant honeycomb SCR denitration catalyst through drying and calcination.
[0029] In some embodiments, the organic binder can be selected from at least one of ammonium carboxymethyl cellulose, hydroxypropyl cellulose, and polyethylene oxide. Among them, the molecular weight of the ammonium carboxymethyl cellulose can be 2 million to 3 million, the molecular weight of the hydroxypropyl cellulose can be 4 million to 6 million, and the molecular weight of the polyethylene oxide can be 1 million to 3 million.
[0030] In some embodiments, the anti-cracking agent can be selected from hydrophilic PP (polypropylene) short fibers and wood fiber cotton. Among them, the diameter of the PP fiber can be 15-30 μm. The anti-cracking agent can play a role in inhibiting the cracking of the wet green body during the drying process.
[0031] In some embodiments, the silica precursor can be selected from glass fiber, silica aerogel or silica sol.
[0032] In some embodiments, the mass ratio of titanium dioxide, organic binder, silicon-aluminum composite, anti-cracking agent and silica precursor can be 100:0.5 to 6:5.9 to 28:0.5 to 2:3.5 to 12, preferably 100:0.5 to 3:6 to 21:0.5 to 0.9:3.5 to 9.
[0033] In some embodiments, the active solvent can be deionized water; the alkaline solution can be ammonia water, and the concentration can be 28-40%.
[0034] In some embodiments, the ammonium metavanadate solution can be formed by dissolving ammonium metavanadate in an aqueous solution containing monoethanolamine (concentration 15-20%), and the concentration can be 5-30%, preferably 5-15%.
[0035] In some embodiments, the concentration of the ammonium metatungstate solution can be 16-60%, preferably 20-60%; the concentration of the ammonium molybdate solution can be 10-20%.
[0036] In some embodiments, the zirconia content in the zirconia sol can be 10-15%.
[0037] In some embodiments, the extrusion aid can be at least one of oleic acid, stearic acid, fatty acid preparation containing non-ionic emulsifier, and high degree of polymerization polysaccharide; the pore former can be lactic acid; the water retention agent can be ethylene glycol, propylene glycol, glycerol.
[0038] In some embodiments, the mass ratio of the active solvent, alkaline solution, ammonium metavanadate solution, ammonium metatungstate solution, ammonium molybdate solution, zirconia sol, extrusion aid, pore former and water retention agent can be 100:40 to 60:125:150:125:110 to 240:5 to 25:5 to 10:5 to 11, preferably 100:40 to 60:125:150:125:110 to 140:5 to 25:5 to 10:5 to 11.
[0039] In some embodiments, the ratio of the total mass of the dry mixed materials to the total mass of the active solvent, alkaline solution, ammonium metavanadate solution, ammonium metatungstate solution, ammonium molybdate solution, zirconia sol, extrusion aid, pore former and water retention agent can be controlled to be 100:40 to 70, preferably 100:60 to 70.
[0040] In some embodiments, the pH of the mud can be adjusted using ammonia water or organic base. Among them, the organic base can be methanol ammonia, monoethanolamine, diethanolamine.
[0041] In some embodiments, the moisture content of the mud material can be controlled to be 25-27%, and the pH can be 8.0-10. During the forming process, if the moisture content of the mud material is too high, the strength of the wet embryo will be too low; if the moisture content is too low, the mud material will be too hard to form. At the same time, controlling the appropriate alkalinity can promote the stability of the mud material.
[0042] In some embodiments, the retting can be carried out in a retting bag, and it is retted for 18-36 hours in a closed and light-shielded manner at room temperature. Retting is beneficial to keep the moisture and temperature in the mud material consistent and uniform.
[0043] In some embodiments, the forming process can be: first filtering and pre-extruding the retted mud material into bricks, and then extruding and forming it through a twin-screw extruder.
[0044] In some embodiments, the drying temperature can be 30-120 °C, and the drying time can be 5-12 days.
[0045] In some embodiments, the calcination process can be: using a mesh belt furnace to increase the temperature from 30 °C to the maximum calcination temperature of 500-680 °C in a programmed manner, controlling the mesh belt speed to be 1.5-3 m / h, and the calcination time to be 17-35 hours, with the maximum calcination temperature maintained for 4-8 hours.
[0046] The catalyst obtained by the preparation method provided by the present invention uses a composite of three species, namely titanium dioxide, nano-zirconia, and silica-alumina composite, as the carrier. Adding nano-zirconia in the form of zirconium sol to the mud material can promote the bonding strength between titanium dioxide particles, improve the mechanical strength and thermal stability of the catalyst, and the silica-alumina composite and zirconia itself have relatively high strength, realizing the enhancement of the wear strength of the honeycomb catalyst.
[0047] Compared with the existing honeycomb denitration catalyst, the wear-resistant honeycomb denitration catalyst provided by the present invention has excellent denitration performance, and its wear rate can be reduced from 0.079% / kg to 0.009% / kg, which can significantly extend the service life of the catalyst.
[0048] The following further lists examples to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention, and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are only an example within the appropriate range, that is, those skilled in the art can make selections within the appropriate range through the description in this article, rather than being limited to the specific values in the following examples.
[0049] Example 1
[0050] The preparation method of the wear-resistant honeycomb SCR denitration catalyst provided in Embodiment 1 includes the following steps: (1) Add 1065 kg of anatase titanium dioxide (specific surface area of 120 m 2 / g), 11 kg of polyethylene oxide, 3.1 kg of hydroxypropyl cellulose, 63 kg of silica-alumina composite, 6.2 kg of modified polypropylene short fibers, and 38 kg of glass short fibers into an inclined large-scale mixer and perform dry mixing for 15 minutes; Under the stirring of the mixer, sequentially add 100 kg of deionized water, 60 kg of concentrated ammonia water (concentration of 28%), 125 kg of ammonium metavanadate solution (33.2 kg of ammonium metavanadate), 150 kg of ammonium metatungstate solution (24.8 kg of ammonium metatungstate), 125 kg of ammonium heptamolybdate solution (23.5 kg of ammonium heptamolybdate), 110 kg of zirconium sol (zirconia content of 15%), 25 kg of fatty acid preparation containing non-ionic emulsifier, 6 kg of lactic acid, and 5 kg of glycerol to the mixed dry materials, stir for 1.5 hours until the materials are uniform, evacuate to drain and dehumidify, control the moisture content of the mud to be 26%, and add appropriate ammonia water to adjust the pH of the mud to 8.0 - 10; (2) Put the obtained mud into a aging bag and age it in a closed and light-shielded manner at room temperature for 36 hours; (3) First filter and pre-extrude the above-mentioned mud into bricks, and then extrude and form it through a twin-screw extruder to obtain a honeycomb denitration catalyst green body; (4) Place the green body in a drying chamber and dry it according to the temperature and humidity curve program with temperature rising and humidity decreasing. The drying time is 12 days to obtain a catalyst dry green body; (5) Place the catalyst dry green body in a mesh belt furnace, program the temperature from 30°C to 600°C, control the mesh belt speed at 3 m / h, and calcine for 17 hours, with a constant temperature of 600°C for 6 hours to obtain the wear-resistant honeycomb SCR denitration catalyst.
[0051] Embodiment 2
[0052] The preparation method of the wear-resistant honeycomb SCR denitration catalyst provided in Embodiment 2 includes the following steps: (1) Add 1010 kg of rutile titanium dioxide (specific surface area of 300 m 2 / g), 9 kg of polyethylene oxide, 8.1 kg of ammonium carboxymethyl cellulose, 75 kg of silica-alumina composite, 7.8 kg of modified polypropylene short fibers, and 63.5 kg of glass short fibers into an inclined large-scale mixer and perform dry mixing for 25 minutes; Under the stirring of a kneader, 100 kg of deionized water, 40 kg of concentrated ammonia water (concentration 40%), 125 kg of ammonium metavanadate solution (ammonium metavanadate 33.2 kg), 150 kg of ammonium metatungstate solution (ammonium metatungstate 42 kg), 125 kg of ammonium heptamolybdate solution (ammonium heptamolybdate 23.5 kg), 160 kg of zirconium sol (zirconia content 15%), 5.0 kg of stearic acid, 9.1 kg of lactic acid and 6.2 kg of ethylene glycol were sequentially added to the mixed dry materials. Stir for 1 hour until the materials are uniform, evacuate to drain water and remove moisture, control the moisture content of the mud to 25%, and add appropriate ammonia water to adjust the pH of the mud to 8.0 - 10; (2) Put the obtained mud into a aging bag and age it in a sealed and light-shielded manner at room temperature for 24 hours; (3) First filter and pre-extrude the above mud into bricks, and then extrude and form it through a twin-screw extruder to obtain a honeycomb denitration catalyst green body; (4) Place the green body in a drying room and dry it according to the temperature and humidity curve by programmed heating and humidity reduction. The drying time is 7 days; obtain the catalyst dry green body; (5) Place the catalyst dry green body in a mesh belt furnace, heat it from 30°C to 510°C by program, control the mesh belt speed at 2 m / h, and calcine for 25 hours, with a constant temperature of 510°C for 8 hours to obtain a wear-resistant honeycomb SCR denitration catalyst.
[0053] Example 3
[0054] The preparation method of the wear-resistant honeycomb SCR denitration catalyst provided in this Example 3 includes the following steps: (1) Add 900 kg of anatase titanium dioxide (specific surface area 300 m 2 / g), 5 kg of polyethylene oxide, 12 kg of ammonium carboxymethyl cellulose, 185 kg of silica-alumina composite, 4.5 kg of wood fiber wool, and 82 kg of short glass fibers to an inclined large kneader and dry mix for 20 minutes; Under the stirring of the kneader, 100 kg of deionized water, 50 kg of concentrated ammonia water (concentration 28%), 125 kg of ammonium metavanadate solution (ammonium metavanadate 17 kg), 150 kg of ammonium metatungstate solution (ammonium metatungstate 54 kg), 125 kg of ammonium heptamolybdate solution (ammonium heptamolybdate 14.5 kg), 240 kg of zirconium sol (zirconia content 15%), 3.8 kg of high-polymerization polysaccharide and 4.3 kg of oleic acid, 5.2 kg of lactic acid and 10 kg of ethylene glycol were sequentially added to the mixed dry materials. Stir for 1.5 hours until the materials are uniform, evacuate to drain water and remove moisture, control the moisture content of the mud to 26%, and add appropriate ammonia water to adjust the pH of the mud to 8.0 - 10; (2) Put the obtained mud into a aging bag and age it in a sealed and light-shielded manner at room temperature for 20 hours; (3) Filter and pre - extrude the above - mentioned mud into bricks first, and then extrude and form it through a twin - screw extruder to obtain a wet honeycomb denitration catalyst body; (4) Place the wet body in a drying chamber, and dry it by heating up and reducing humidity according to the temperature - humidity curve program. The drying time is 10 days to obtain a dry catalyst body; (5) Place the dry catalyst body in a mesh - belt furnace, heat it up from 30 °C to 650 °C in a programmed manner, control the mesh - belt speed at 2.5 m / h, and calcine it for 20 hours, with a constant temperature of 650 °C for 4 hours to obtain a wear - resistant honeycomb SCR denitration catalyst.
[0055] Figure 1 It is the scanning electron micrograph of the catalyst sample prepared in Example 3. It can be seen from the figure that the surface of the catalyst sample prepared in Example 3 is relatively smooth without cracks and has relatively high strength at the same time.
[0056] Comparative Example 1
[0057] The preparation method of the wear - resistant honeycomb SCR denitration catalyst provided in this Comparative Example 1 includes the following steps: (1) Add 1030 kg of anatase titanium dioxide (specific surface area is 300 m 2 / g), 11 kg of polyethylene oxide, 8 kg of ammonium carboxymethylcellulose, 4.5 kg of wood fiber wool, and 68 kg of short glass fibers into an inclined large - scale mixer and dry - mix for 20 minutes; Under the condition of stirring in the mixer, add 100 kg of deionized water, 50 kg of concentrated ammonia water (concentration is 28%), 125 kg of ammonium metavanadate solution (17 kg of ammonium metavanadate), 150 kg of ammonium metatungstate solution (54 kg of ammonium metatungstate), 125 kg of ammonium heptamolybdate solution (14.5 kg of ammonium heptamolybdate), and 5.2 kg of lactic acid in sequence to the mixed dry materials, stir for 1.5 hours until the materials are uniform, evacuate and drain water to remove moisture, control the moisture content of the mud at 26%, and add appropriate ammonia water to adjust the pH of the mud to 8.0 - 10; (2) Put the obtained mud into a aging bag and age it for 36 hours in a closed and light - shielded manner at room temperature; (3) Filter and pre - extrude the above - mentioned mud into bricks first, and then extrude and form it through a twin - screw extruder to obtain a wet honeycomb denitration catalyst body; (4) Place the wet body in a drying chamber, and dry it by heating up and reducing humidity according to the temperature - humidity curve program. The drying time is 10 days to obtain a dry catalyst body; (5) Place the dry catalyst body in a mesh - belt furnace, heat it up from 30 °C to 650 °C in a programmed manner, control the mesh - belt speed at 2.5 m / h, and calcine it for 20 hours, with a constant temperature of 650 °C for 4 hours to obtain a honeycomb SCR denitration catalyst.
[0058] Figure 2Scanning electron micrograph of the catalyst sample prepared in Comparative Example 1. It can be seen from the figure that the surface of the catalyst sample prepared in Comparative Example 1 is relatively rough and there are tiny cracks, and it is easy to wear.
[0059] The main components and their mass fractions of the denitration catalysts prepared in Examples 1 to 3 and Comparative Example 1 are as follows in the table: Table 1 Main components and their mass fractions of the catalysts in Examples 1 to 3 and Comparative Example 1
[0060] The denitration catalysts prepared in Examples 1 to 3 and Comparative Example 1 were tested for mechanical properties according to the national standard, and the results are as follows in the table: Table 2 Mechanical properties of the catalysts in Examples 1 to 3 and Comparative Example 1 sample Example 1 Example 2 Example 3 Comparative Example 1 Axial compressive strength / MPa 5.2 5.1 5.8 3.8 Radial compressive strength / MPa 1.9 2 2.4 1.1 Wear rate / (% / kg) 0.026 0.015 0.009 0.079
[0061] It can be seen from Table 2 that the axial compressive strength, radial compressive strength and attrition rate of the catalysts prepared in Examples 1 to 3 are far superior to those of the catalyst prepared in Comparative Example 1, and the attrition rate of Example 3 is as low as 0.009% / kg.
[0062] Although the content of the present invention has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be regarded as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.
Claims
1. A wear-resistant honeycomb SCR denitration catalyst, characterized in that, the chemical composition of the wear-resistant honeycomb SCR denitration catalyst includes: by mass parts, 70-90 parts of titanium dioxide, 0.4-5 parts of vanadium pentoxide, 1-5 parts of tungsten trioxide, 0.5-3 parts of molybdenum trioxide, 1-10 parts of zirconium dioxide, 3-10 parts of silicon dioxide, and 3-15 parts of silicon-aluminum composite.
2. The wear-resistant honeycomb SCR denitration catalyst according to claim 1, characterized in that, The titanium dioxide is anatase titanium dioxide with a specific surface area of 120 to 300 m 2 / g; wherein, the D90 of the particle size of the titanium dioxide is < 5 μm, the D50 is < 1 μm, and the average grain size is 5 to 15 nm; the silicon-aluminum composite is a porous silicon-aluminum molecular sieve with strong acidity, a low-crystallinity silicon-aluminum oxide or an amorphous strong-acid silicon-aluminum oxide, preferably at least one of ITQ-1, ITQ-7, ITQ-10 or an aluminum-containing silicon molecular sieve.
3. A preparation method of the wear-resistant honeycomb SCR denitration catalyst according to claim 1 or 2, characterized in that, the preparation method includes the following steps: (1) Dry-mix titanium dioxide, an organic binder, a silicon-aluminum composite, an anti-cracking agent and a silicon dioxide precursor, and at the same time add an active solvent, an alkaline solution, an ammonium metavanadate solution, an ammonium metatungstate solution, an ammonium molybdate solution, a zirconium dioxide sol, an extrusion aid, a pore-forming agent and a water retention agent to the dry-mixed materials, stir for 1-1.5 hours to mix evenly and then adjust the pH to obtain a mud; (2) Age and shape the mud in sequence to obtain a green body; (3) Dry and calcine the green body to obtain the wear-resistant honeycomb SCR denitration catalyst.
4. The preparation method according to claim 3, characterized in that, the organic binder is selected from at least one of ammonium carboxymethyl cellulose, hydroxypropyl cellulose, and polyethylene oxide; wherein, the molecular weight of the ammonium carboxymethyl cellulose is 2 million - 3 million, the molecular weight of the hydroxypropyl cellulose is 4 million - 6 million, and the molecular weight of the polyethylene oxide is 1 million - 3 million; the anti-cracking agent is selected from hydrophilic PP short fibers and wood fiber wool; wherein, the diameter of the PP fiber is 15-30 μm; the silicon dioxide precursor is selected from modified glass fibers, silicon dioxide aerogels or silica sols.
5. The preparation method according to claim 3 or 4, characterized in that, the mass ratio of titanium dioxide, organic binder, silicon-aluminum composite, anti-cracking agent and silicon dioxide precursor is 100:0.5-6:5.9-28:0.5-2:3.5-12, preferably 100:0.5-3:6-21:0.5-0.9:3.5-9.
6. The preparation method according to any one of claims 3-5, characterized in that, the active solution is deionized water and the alkaline solution is ammonia water; the ammonium metavanadate is dissolved in a 15-20% monoethanolamine solution to form a solution with a concentration of 5-30%, preferably 5-15%; the concentration of the ammonium metatungstate solution is 16-60%, preferably 20-60%; the concentration of the ammonium molybdate solution is 10-20%; the zirconium dioxide content in the zirconium dioxide sol is 10-15%; The extrusion aid is at least one of oleic acid, stearic acid, a fatty acid preparation containing a non-ionic emulsifier, and a high-degree polymerization polysaccharide; the pore-forming agent is lactic acid; the water retention agent is ethylene glycol, propylene glycol, or glycerol.
7. The preparation method according to any one of claims 3-6, characterized in that the mass ratio of the active solvent, the alkaline solution, the ammonium metavanadate solution, the ammonium metatungstate solution, the ammonium molybdate solution, the zirconia sol, the extrusion aid, the pore-forming agent, and the water retention agent is 100:40-60:125:150:125:110-240:5-25:5-10:5-11, preferably 100:40-60:125:150:125:110-140:5-25:5-10:5-11; the ratio of the total mass of the dry-mixed materials to the total mass of the active solvent, the alkaline solution, the ammonium metavanadate solution, the ammonium metatungstate solution, the ammonium molybdate solution, the zirconia sol, the extrusion aid, the pore-forming agent, and the water retention agent is 100:40-70, preferably 100:60-70.
8. The preparation method according to any one of claims 3-7, characterized in that the pH of the mud is adjusted using ammonia water or an organic base; wherein, the organic base is methylamine ammonia, monoethanolamine, or diethanolamine; the moisture content of the mud is 25-27%, and the pH is 8.0-10.
9. The preparation method according to any one of claims 3-8, characterized in that the aging is carried out in an aging bag and aged for 18-36 hours in a closed and light-shielded manner at room temperature.
10. The preparation method according to any one of claims 3-9, characterized in that the calcination process is: using a mesh belt furnace to increase the temperature from 30°C to the maximum calcination temperature of 500-680°C in a programmed manner, controlling the mesh belt speed to be 1.5-3 m / h, and the calcination time to be 17-35 hours, with the maximum calcination temperature maintained for 4-8 hours.