A highly active anti-sintering SCR denitration catalyst and its preparation process

Abstract

This invention relates to the field of denitrification catalyst technology, specifically to a highly active, anti-sintering SCR denitrification catalyst and its preparation process. The preparation process includes: kneading montmorillonite, functional additives, titanium dioxide, silica sol, and stearic acid to obtain a mixture; sequentially adding ammonium metavanadate, ammonium metatungstate, and niobium oxalate and mixing thoroughly; then adding glass fiber, adjusting the pH, and adding carboxymethyl cellulose and polyethylene oxide; followed by aging, extrusion, drying, and calcination to form a honeycomb catalyst. The functional additive uses porous cerium oxide prepared from glucose and crotonamide as a carrier, with manganese oxide loaded on its surface via liquid-phase deposition, exhibiting a distinct core-shell structure. The SCR denitrification catalyst prepared by this invention significantly improves the catalyst's thermal stability and anti-sintering ability while ensuring high denitrification activity, possessing significant practical value and broad market prospects.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalyst technology, specifically to a highly active anti-sintering SCR denitrification catalyst and its preparation process. Background Technology

[0002] Nitrogen oxides (NOx), a major source of atmospheric pollution, mainly include N2O, NO, N2O2, N2O3, NO2, N2O4, and N2O5. Among these, NO and NO2 are the most serious pollutants. NOx emissions exacerbate environmental degradation. On the one hand, under certain conditions, NOxes combine with hydrocarbons to form photochemical smog, damaging the atmospheric environment and harming human health. On the other hand, NOxes are a primary cause of acid rain. In fact, most anthropogenic NOx emissions originate from the combustion of fossil fuels. Thermal power generation, steel sintering, waste incineration, glass kilns, and cement kilns are all major sources of NOx. GB13271-2014, the "Emission Standard of Air Pollutants for Boilers," stipulates that the concentration of NOx emissions from the tail gas of newly built coal-fired boilers should not exceed 300 mg / Nm³. 3 The concentration of nitrogen oxide emissions from the exhaust gas of newly built gas-fired boilers shall not exceed 200 mg / Nm³. 3 GB13223-2011, the "Emission Standard of Air Pollutants for Thermal Power Plants," stipulates that the concentration of nitrogen oxides emitted from the exhaust gas of newly built coal-fired boilers shall not exceed 100 mg / Nm³. 3 The concentration of nitrogen oxide emissions from the exhaust gas of the gas turbine unit shall not exceed 50 mg / Nm³. 3 It is worth noting that local governments formulate their own air pollutant emission standards based on their specific circumstances and in accordance with national standards. Some regions require that the concentration of nitrogen oxides in the exhaust gas from coal-fired / gas-fired boilers not exceed 50 mg / Nm³. 3 Currently, flue gas denitrification generally uses SNCR or SCR. SNCR denitrification technology is a selective non-catalytic reduction technology that does not use a catalyst. It involves injecting an ammonia reducing agent into the furnace to remove NOx gas from the flue gas and generate nitrogen and water.

[0003] Selective catalytic reduction (SCR) technology is currently the most widely used and mature flue gas denitrification technology for power plant boilers and industrial furnaces, and its core lies in the catalyst. Commercial SCR catalysts typically use V₂O₅ as the active component, WO₃ or MoO₃ as an auxiliary agent, and TiO₂ as a support. However, these traditional vanadium-titanium catalysts have significant limitations: First, their optimal activity temperature window is relatively high (usually 300-400℃), making it difficult to adapt to the low-to-medium temperature flue gas conditions of 250-350℃ commonly found in non-power industries such as coking, sintering, and glass furnaces; second, vanadium species have certain biotoxicity, posing a potential risk of secondary pollution; third, under long-term high-temperature operation or drastic temperature fluctuations, the active component is prone to sintering and grain growth, leading to a decrease in specific surface area and active sites, accelerating catalyst deactivation.

[0004] To meet the demands of low- and medium-temperature flue gas denitrification, researchers have developed various low-temperature SCR catalyst systems. For example, cerium-based catalysts have attracted attention due to their excellent oxygen storage and release capabilities and redox properties, while iron-based and manganese-based catalysts have also shown good low-temperature activity. However, these low-temperature catalysts often face the challenge of insufficient thermal stability. Although they exhibit activity in the low- and medium-temperature range, their resistance to sintering is weak under actual flue gas temperature fluctuations or short-term high-temperature shocks, limiting their service life. Furthermore, maintaining high denitrification efficiency and suppressing ammonia slip in industrial flue gas with high space velocities and complex compositions remains a technical challenge. Summary of the Invention

[0005] This invention provides a highly active anti-sintering SCR denitration catalyst and its preparation process. The prepared SCR denitration catalyst significantly improves the thermal stability and anti-sintering ability of the catalyst while ensuring high denitration activity, and has significant practical value and broad market prospects.

[0006] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a preparation process for a highly active anti-sintering SCR denitration catalyst, comprising the following steps: Step 1: By weight, add 15-25 parts montmorillonite, 10-20 parts functional additives, 20-50 parts anatase titanium dioxide, 10-20 parts silica sol and 0.4-0.6 parts stearic acid to a kneader and mix until there is no obvious stratification to obtain the mixture. Step 2: Add 0.5-1.5 parts ammonium metavanadate, 1-2 parts ammonium metatungstate, and 4-6 parts niobium oxalate to the mixture in sequence, and stir evenly at 60±5℃. The moisture content of the resulting mud should be controlled at 35-45 wt%. Step 3: Add 3-4 parts of glass fiber to the mud, stir evenly, then add ammonia water to adjust the pH of the resulting mixed slurry to 7.5-8.5; then add 0.8-1 parts of carboxymethyl cellulose and 0.4-0.6 parts of polyethylene oxide, stir thoroughly, and evaporate until the moisture content is 26±1wt%; remove the mud, seal it with plastic wrap and age it for 10-15 hours to obtain aged mud. Step 4: Extrude the aged mud into strips or blocks, then put them into an extruder and extrude the honeycomb catalyst semi-finished product through a mold. After drying and calcination, it is ready.

[0007] Furthermore, the drying temperature is 60-110℃, and the moisture content in the finished catalyst product after drying is ≤5wt%.

[0008] Furthermore, the calcination temperature is 450-600℃, and the calcination time is 15-25h.

[0009] Furthermore, the inner wall thickness of the mold is 0.4-0.7 mm, the outer wall thickness is 0.9-1.35 mm, and the SCR denitrification catalyst is a honeycomb catalyst with 16-25 pores.

[0010] Furthermore, the preparation method of the functional additive is as follows: a porous carrier is uniformly dispersed in a 2-4 wt% PVP (polyvinylpyrrolidone) aqueous solution at a dosage ratio of 5-10 g / L. After magnetic stirring for 4-6 h, a manganese sulfate aqueous solution with a volume of 20-30% of the PVP aqueous solution is added. After magnetic stirring for 30-40 min, a potassium dichromate aqueous solution with a volume of 4-6 times that of the manganese sulfate aqueous solution is added dropwise. The reaction is carried out at 30-50℃ for 30-50 min. The reaction solution is then filtered, washed, and dried sequentially to obtain the functional additive. The concentration of the manganese sulfate aqueous solution is 20-30 mmol / L, the concentration of the potassium dichromate aqueous solution is 5-20 mmol / L, and the dropping rate of the potassium dichromate aqueous solution is 10-20 mL / min. The drying temperature is 60-80℃, and the drying time is 8-12 h.

[0011] Furthermore, the porous support is prepared by adding glucose and crotonamide sequentially to a 0.05-0.2 mol / L cerium nitrate aqueous solution, mixing and stirring until homogeneous, adjusting the pH to 9-11 with 25-30 wt% ammonia, stirring the resulting gel at 200-300 r / min for 6-10 h, reacting at 200-300℃ for 50-80 h, separating the solid and liquid phases of the reaction solution, washing the filter cake alternately with deionized water and ethanol 3-5 times, and then vacuum drying and high-temperature sintering to obtain the final product; wherein the molar concentration ratio of glucose, cerium nitrate, and crotonamide in the mixed system is 1:1-1.5:1-2.

[0012] Furthermore, the vacuum drying temperature is 80-100℃, and the drying time is 3-6 hours.

[0013] Furthermore, the high-temperature sintering temperature is 500-600℃, and the high-temperature sintering time is 6-10h.

[0014] Secondly, the present invention provides a highly active anti-sintering SCR denitration catalyst, which is prepared by the preparation process described above.

[0015] The roles of each raw material are as follows: 1. Anatase titanium dioxide: specific surface area 80-100m² 2 / g, with a particle size distribution D50 ranging from 0.8 to 1.2 μm, its main function is to form the main structure of the catalyst, with a large specific surface area, serving as a support for the active components of the catalyst; 2. Montmorillonite: Main components are SiO2, Al2O3, MgO, and Fe2O3, containing small amounts of elements such as Ca, K, and Na. Its specific surface area is 100-120 m². 2 / g, particle size D90<18μm, mainly functions to form the main structure of the catalyst, with large specific surface area, low thermal expansion coefficient of ceramic support catalyst, high stability, good thermal shock resistance, and improves the catalyst's resistance to sintering in high temperature environment; 3. Ammonium metavanadate: The main active component of denitrification catalysts. Vanadium is currently recognized as the most stable denitrification element.

[0016] 4. Ammonium metatungstate: It is readily soluble in water, and its aqueous solution is acidic. It improves the catalyst's resistance to sintering and enhances the catalyst's thermal stability.

[0017] 5. Silica sol: Alkaline silica sol, pH value 9-10.5, SiO2 content 30±1%, Na2O content ≤0.3%, viscosity at 25℃ ≤7.0, average particle size 7-20nm, carrier binder, silicon source, improves the density of catalyst extrusion slurry, and enhances the structural strength of honeycomb catalyst.

[0018] 6. Niobium oxalate: Easily soluble in water, the aqueous solution is acidic. Its main function is that Nb2O5 is a solid acid, which increases the number of acidic sites on the catalyst surface and improves the catalyst activity. Niobium has good anti-sintering ability, which improves the anti-sintering ability of the honeycomb denitrification catalyst at high temperature.

[0019] 7. Glass fiber: The main components are SiO2, Al2O3, CaO, B2O3, MgO, and Na2O. Glass fiber plays a skeletal role in the catalyst, improving the structural strength of the catalyst.

[0020] 8. Stearic acid: Improves the smoothness of the mud during the mixing process, and acts as a release agent during the extrusion of the honeycomb catalyst, reducing the friction between the mud and the extrusion die.

[0021] 9. Lactic acid: a solubilizer and adsorbent, which improves the solubility and adsorption of active components in the mud.

[0022] 10. Carboxymethyl cellulose: viscosity range 150-250, pore-forming agent, improves the water absorption and retention of clay, and improves the plasticity of clay.

[0023] 11. Polyethylene oxide (PEO): viscosity range 250-350, thickener, flocculant, lubricant, improves the plasticity of mud.

[0024] 12. Ammonia water: pH adjuster for clay. Alkaline clay has better plasticity and is more conducive to the extrusion molding of honeycomb catalysts.

[0025] Compared with the prior art, the beneficial effects of the present invention are: This invention uses cerium nitrate, glucose, and crotonamide as raw materials to prepare spherical cerium oxide with a porous morphology, i.e., a porous support, through a chemical reaction. The obtained porous support is then dispersed in a PVP aqueous solution, magnetically stirred until homogeneous, and then manganese sulfate aqueous solution and potassium dichromate aqueous solution are added sequentially. After a chemical reaction, a large amount of metallic manganese oxide is loaded onto the surface of the porous support. The resulting functional additive has a distinct core-shell structure with the porous support as the "core" layer and the metallic manganese oxide as the "shell" layer. Simultaneously, the metallic manganese oxide in the functional additive exhibits excellent low-temperature SCR catalytic activity, effectively reducing the onset temperature of the denitrification reaction; while cerium oxide possesses excellent oxygen storage / release capacity and redox cycle characteristics. The synergistic effect of these two components significantly enhances the catalytic oxidation conversion efficiency of nitrogen oxides, significantly broadening the active temperature window of the SCR denitrification catalyst.

[0026] Secondly, the functional additives themselves possess extremely high thermal stability. Their three-dimensional porous structure maintains good porosity and specific surface area even under high-temperature calcination and long-term operation conditions, effectively inhibiting grain growth and phase transformation of the active components vanadium, niobium, tungsten, and the carrier titanium dioxide at high temperatures. Simultaneously, the manganese-cerium composite oxide is uniformly anchored on the surface of the porous support, preventing the migration and aggregation of active components, significantly improving the anti-sintering performance of the SCR denitrification catalyst, and effectively extending the catalyst's lifespan. Furthermore, the functional additives, in conjunction with niobium oxide, increase the density of acidic sites on the catalyst surface, enhancing the adsorption and activation capacity for the reducing agent ammonia, thereby achieving higher denitrification efficiency and lower ammonia slip under the same ammonia-nitrogen molar ratio.

[0027] In summary, the SCR denitration catalyst prepared by this invention significantly improves the catalyst's thermal stability and anti-sintering ability while ensuring high denitration activity, and has significant practical value and broad market prospects. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1 A preparation process for a highly active anti-sintering SCR denitration catalyst includes the following steps: Step 1: By weight, add 15 parts montmorillonite, 10 parts functional additives, 20 parts anatase titanium dioxide, 10 parts silica sol and 0.4 parts stearic acid to a kneader and mix until there is no obvious stratification to obtain the mixture. Step 2: Add 0.5 parts ammonium metavanadate, 1 part ammonium metatungstate, and 4 parts niobium oxalate to the mixture in sequence, and stir evenly at 55°C. The moisture content of the resulting mud should be controlled at 35 wt%. Step 3: Add 3 parts of glass fiber to the mud, stir evenly, add ammonia water, and adjust the pH value of the resulting mixed slurry to 7.5; then add 0.8 parts of carboxymethyl cellulose and 0.4 parts of polyethylene oxide, stir thoroughly, and evaporate to a moisture content of 25 wt%; take out the mud, seal it with plastic wrap and age it for 15 hours to obtain aged mud. Step 4: Extrude the aged mud into strips or blocks, then put them into an extruder and extrude the honeycomb catalyst semi-finished product through a mold. After drying and calcination, it is ready. The drying temperature was 60℃, and the moisture content of the finished catalyst product after drying was 5 wt%. The calcination temperature was 450℃, and the calcination time was 25 hours. The inner wall thickness of the mold is 0.4 mm, the outer wall thickness is 0.9 mm, and the SCR denitrification catalyst is a 16-pore honeycomb catalyst. The silica sol has a pH of 9, a SiO2 content of 29 wt%, a Na2O content of 0.3 wt%, a viscosity of 7.0 at 25°C, and an average particle size of 7 nm.

[0030] The preparation method of the functional additive is as follows: the porous carrier is uniformly dispersed in a 2wt% PVP aqueous solution at a dosage ratio of 5g / L. After magnetic stirring for 4h, a manganese sulfate aqueous solution with a volume of 20% of the PVP aqueous solution is added. After magnetic stirring for 30min, a potassium dichromate aqueous solution with a volume of 4 times that of the manganese sulfate aqueous solution is added dropwise. After reacting at 30℃ for 50min, the reaction solution is filtered, washed and dried sequentially to obtain the functional additive. The concentration of the manganese sulfate aqueous solution is 20mmol / L, the concentration of the potassium dichromate aqueous solution is 5mmol / L, and the dropping rate of the potassium dichromate aqueous solution is 10mL / min. The drying temperature is 60℃ and the drying time is 12h.

[0031] The porous support was prepared as follows: glucose and crotonamide were added sequentially to a 0.05 mol / L cerium nitrate aqueous solution, mixed and stirred evenly, and the pH was adjusted to 9 with 25 wt% ammonia. The resulting gel was stirred at 200 r / min for 6 h, reacted at 200 °C for 80 h, and then the reaction solution was subjected to solid-liquid separation. The filter cake was washed three times alternately with deionized water and ethanol, and then vacuum dried and sintered at high temperature to obtain the final product. The molar concentration ratio of glucose, cerium nitrate, and crotonamide in the mixed system was 1:1:1. The vacuum drying temperature was 80 °C and the drying time was 6 h. The high-temperature sintering temperature was 500 °C and the high-temperature sintering time was 10 h.

[0032] Example 2 A preparation process for a highly active anti-sintering SCR denitration catalyst includes the following steps: Step 1: By weight, add 20 parts montmorillonite, 15 parts functional additives, 35 parts anatase titanium dioxide, 15 parts silica sol and 0.5 parts stearic acid to a kneader and mix until there is no obvious stratification to obtain the mixture. Step 2: Add 1 part ammonium metavanadate, 2 parts ammonium metatungstate, and 5 parts niobium oxalate to the mixture in sequence, and stir evenly at 60°C. The moisture content of the resulting mud should be controlled at 40 wt%. Step 3: Add 4 parts of glass fiber to the mud, stir evenly, add ammonia water, and adjust the pH value of the resulting mixed slurry to 8; then add 1 part of carboxymethyl cellulose and 0.5 parts of polyethylene oxide, stir thoroughly, and evaporate to a moisture content of 26 wt%; take out the mud, seal it with plastic wrap and age it for 15 hours to obtain aged mud. Step 4: Extrude the aged mud into strips or blocks, then put them into an extruder and extrude the honeycomb catalyst semi-finished product through a mold. After drying and calcination, it is ready. The drying temperature was 90℃, and the moisture content of the finished catalyst product after drying was 5 wt%. The calcination temperature was 550℃, and the calcination time was 20 hours. The inner wall thickness of the mold is 0.5 mm, the outer wall thickness is 1.2 mm, and the SCR denitrification catalyst is a 20-pore honeycomb catalyst; The silica sol has a pH of 10, a SiO2 content of 30 wt%, a Na2O content of 0.3 wt%, a viscosity of 7.0 at 25°C, and an average particle size of 10 nm.

[0033] The preparation method of the functional additive is as follows: the porous carrier is uniformly dispersed in a 3wt% PVP aqueous solution at a dosage ratio of 10g / L. After magnetic stirring for 5h, a manganese sulfate aqueous solution with a volume of 25% of the PVP aqueous solution is added. After magnetic stirring for 35min, a potassium dichromate aqueous solution with a volume of 5 times that of the manganese sulfate aqueous solution is added dropwise. After reacting at 40℃ for 40min, the reaction solution is filtered, washed and dried sequentially to obtain the functional additive. The concentration of the manganese sulfate aqueous solution is 25mmol / L, the concentration of the potassium dichromate aqueous solution is 10mmol / L, and the dropping rate of the potassium dichromate aqueous solution is 15mL / min. The drying temperature is 70℃ and the drying time is 10h.

[0034] The porous support was prepared as follows: glucose and crotonamide were added sequentially to a 0.1 mol / L cerium nitrate aqueous solution, mixed and stirred evenly, and the pH was adjusted to 10 with 25 wt% ammonia. The resulting gel was stirred at 250 r / min for 8 h, and reacted at 250 °C for 60 h. The reaction solution was then subjected to solid-liquid separation. The filter cake was washed four times alternately with deionized water and ethanol, and then vacuum dried and sintered at high temperature to obtain the final product. The molar ratio of glucose, cerium nitrate, and crotonamide in the mixed system was 1:1.5:2. The vacuum drying temperature was 90 °C and the drying time was 5 h. The high-temperature sintering temperature was 550 °C and the high-temperature sintering time was 8 h.

[0035] Example 3 A preparation process for a highly active anti-sintering SCR denitration catalyst includes the following steps: Step 1: By weight, add 25 parts montmorillonite, 20 parts functional additives, 50 parts anatase titanium dioxide, 20 parts silica sol and 0.6 parts stearic acid to a kneader and mix until there is no obvious stratification to obtain the mixture. Step 2: Add 1.5 parts ammonium metavanadate, 2 parts ammonium metatungstate, and 6 parts niobium oxalate to the mixture in sequence, and stir evenly at 65°C. The moisture content of the resulting mud should be controlled at 45 wt%. Step 3: Add 4 parts of glass fiber to the mud, stir evenly, add ammonia water, and adjust the pH value of the resulting mixed slurry to 8.5; then add 1 part of carboxymethyl cellulose and 0.6 parts of polyethylene oxide, stir thoroughly, and evaporate to a moisture content of 27 wt%; take out the mud, seal it with plastic wrap and age it for 10 hours to obtain aged mud. Step 4: Extrude the aged mud into strips or blocks, then put them into an extruder and extrude the honeycomb catalyst semi-finished product through a mold. After drying and calcination, it is ready. The drying temperature was 110℃, and the moisture content of the finished catalyst product after drying was 4 wt%. The calcination temperature was 600℃, and the calcination time was 15 hours. The inner wall thickness of the mold is 0.7 mm, the outer wall thickness is 1.35 mm, and the SCR denitration catalyst is a 25-pore honeycomb catalyst. The silica sol has a pH of 10.5, a SiO2 content of 31 wt%, a Na2O content of 0.3 wt%, a viscosity of 7.0 at 25°C, and an average particle size of 20 nm.

[0036] The preparation method of the functional additive is as follows: the porous carrier is uniformly dispersed in a 4wt% PVP aqueous solution at a dosage ratio of 10g / L. After magnetic stirring for 6h, a manganese sulfate aqueous solution with a volume of 30% of the PVP aqueous solution is added. After magnetic stirring for 40min, a potassium dichromate aqueous solution with a volume of 6 times that of the manganese sulfate aqueous solution is added dropwise. After reacting at 50℃ for 30min, the reaction solution is filtered, washed and dried sequentially to obtain the functional additive. The concentration of the manganese sulfate aqueous solution is 30mmol / L, the concentration of the potassium dichromate aqueous solution is 20mmol / L, and the dropping rate of the potassium dichromate aqueous solution is 20mL / min. The drying temperature is 80℃ and the drying time is 8h.

[0037] The porous support was prepared as follows: glucose and crotonamide were added sequentially to a 0.2 mol / L cerium nitrate aqueous solution, mixed and stirred evenly, and the pH was adjusted to 11 with 30 wt% ammonia. The resulting gel was stirred at 300 r / min for 10 h, reacted at 300 °C for 50 h, and then the reaction solution was subjected to solid-liquid separation. The filter cake was washed 5 times alternately with deionized water and ethanol, and then vacuum dried and sintered at high temperature to obtain the final product. The molar ratio of glucose, cerium nitrate, and crotonamide in the mixed system was 1:1.5:2. The vacuum drying temperature was 100 °C and the drying time was 3 h. The high-temperature sintering temperature was 600 °C and the high-temperature sintering time was 6 h.

[0038] Comparative Example 1: The difference between this comparative example and Example 1 is that the highly active anti-sintering SCR denitration catalyst prepared in this comparative example does not contain functional additives.

[0039] Comparative Example 2: The difference between this comparative example and Example 1 is that an equal amount of porous carrier is used to replace the functional additive in this comparative example.

[0040] Performance testing: 1. Denitrification efficiency: The performance of the SCR denitrification catalysts provided in Examples 1-3 and Comparative Examples 1-2 was tested and evaluated under simulated flue gas conditions. NH3 was used as the reducing agent, and the typical flue gas conditions were: NO 500 ppm, SO2 300 ppm, O2 5% (v / v), H2O 10% (v / v), ammonia-to-nitrogen ratio of 1:1, N2 as the balance gas, and a space velocity of 5000 h⁻¹. -1 The flue gas flow rate was 300 mL / min. A fixed-bed reactor was used to test the denitrification efficiency of the SCR catalyst at different temperatures. The NO concentration at the inlet and outlet of the SCR reactor was measured using a flue gas analyzer. The denitrification efficiency was calculated using the following formula: Denitrification efficiency / % = (C in- C out ) / C in ×100%; In the formula, C in NO concentration (ppm) at the inlet of the SCR reactor; C out The NO concentration (ppm) at the outlet of the SCR reactor.

[0041] 2. Compressive strength: The compressive strength of the SCR denitrification catalysts prepared in each group was tested according to the GBT 31587-2015 standard.

[0042] The test data obtained above are recorded in Table 1.

[0043] Table 1. Denitrification efficiency and compressive strength test results of each group of SCR denitrification catalysts.

[0044] By comparing and analyzing the relevant data in the table, it can be seen that the SCR denitration catalyst prepared by this invention, while ensuring high denitration activity, significantly improves the catalyst's thermal stability and anti-sintering ability, demonstrating significant practical value and broad market prospects. This indicates that the highly active anti-sintering SCR denitration catalyst and its preparation process provided by this invention have broader market prospects and are more suitable for widespread application.

[0045] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preparation process for a highly active anti-sintering SCR denitration catalyst, characterized in that, Includes the following steps: Step 1: By weight, add 15-25 parts montmorillonite, 10-20 parts functional additives, 20-50 parts anatase titanium dioxide, 10-20 parts silica sol and 0.4-0.6 parts stearic acid to a kneader and mix until there is no obvious stratification to obtain the mixture. Step 2: Add 0.5-1.5 parts ammonium metavanadate, 1-2 parts ammonium metatungstate, and 4-6 parts niobium oxalate to the mixture in sequence, and stir evenly at 60±5℃. The moisture content of the resulting mud should be controlled at 35-45 wt%. Step 3: Add 3-4 parts of glass fiber to the mud, stir evenly, then add ammonia water to adjust the pH of the resulting mixed slurry to 7.5-8.5; then add 0.8-1 parts of carboxymethyl cellulose and 0.4-0.6 parts of polyethylene oxide, stir thoroughly, and evaporate until the moisture content is 26±1wt%; remove the mud, seal it with plastic wrap and age it for 10-15 hours to obtain aged mud. Step 4: Extrude the aged mud into strips or blocks, then put them into an extruder and extrude the honeycomb catalyst semi-finished product through a mold. After drying and calcination, it is ready. The preparation method of the functional additive in step one is as follows: A porous carrier is uniformly dispersed in a 2-4 wt% PVP aqueous solution at a dosage ratio of 5-10 g / L. After magnetic stirring for 4-6 hours, a manganese sulfate aqueous solution with a volume of 20-30% of the PVP aqueous solution is added. After magnetic stirring for 30-40 minutes, a potassium dichromate aqueous solution with a volume of 4-6 times that of the manganese sulfate aqueous solution is added dropwise. The reaction is carried out at 30-50℃ for 30-50 minutes. The reaction solution is then filtered, washed, and dried sequentially to obtain the functional additive. The concentration of the manganese sulfate aqueous solution is 20-30 mmol / L, and the concentration of the potassium dichromate aqueous solution is 5-20 mmol / L. The dropping rate of the potassium dichromate aqueous solution is 10-20 mL / min. The drying temperature is 60-80℃, and the drying time is 8-12 hours. The porous carrier in the functional additive is prepared as follows: glucose and crotonamide are added to a 0.05-0.2 mol / L cerium nitrate aqueous solution, mixed and stirred evenly, and the pH is adjusted to 9-11 with 25-30 wt% ammonia water. The resulting gel is stirred at 200-300 r / min for 6-10 h, and reacted at 200-300℃ for 50-80 h. The reaction solution is then subjected to solid-liquid separation, and the filter cake is washed alternately with deionized water and ethanol 3-5 times. After vacuum drying and high-temperature sintering, the product is obtained.

2. The preparation process of a highly active anti-sintering SCR denitration catalyst according to claim 1, characterized in that: The drying temperature is 60-110℃, and the moisture content in the finished catalyst product after drying is ≤5wt%.

3. The preparation process of a highly active anti-sintering SCR denitration catalyst according to claim 1, characterized in that: The calcination temperature is 450-600℃, and the calcination time is 15-25h.

4. The preparation process of a highly active anti-sintering SCR denitration catalyst according to claim 1, characterized in that: The inner wall thickness of the mold is 0.4-0.7 mm, the outer wall thickness is 0.9-1.35 mm, and the SCR denitrification catalyst is a honeycomb catalyst with 16-25 pores.

5. The preparation process of a highly active anti-sintering SCR denitration catalyst according to claim 1, characterized in that: The silica sol has a pH of 9-10.5, a SiO2 content of 30±1wt%, a Na2O content of ≤0.3wt%, a viscosity of ≤7.0 at 25℃, and an average particle size of 7-20nm.

6. The preparation process of a highly active anti-sintering SCR denitration catalyst according to claim 1, characterized in that: The vacuum drying temperature is 80-100℃, and the drying time is 3-6 hours.

7. The preparation process of a highly active anti-sintering SCR denitration catalyst according to claim 1, characterized in that: The high-temperature sintering temperature is 500-600℃, and the high-temperature sintering time is 6-10h.

8. A highly active anti-sintering SCR denitration catalyst, characterized in that: It is prepared by the preparation process described in any one of claims 1-7.

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