Preparation method and application of amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning

Abstract

The application relates to a preparation method and application of an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, and belongs to the technical field of selective catalytic reduction catalysts. The problems that existing catalysts are difficult to simultaneously maintain high activity and high stability in a complex atmosphere of ultralow temperature, liquid water and ammonium bisulfate deposition are solved. The catalyst is prepared by the following steps: mixing glacial acetic acid, anhydrous ethanol and ethylene glycol according to a volume ratio of (0.1-3):(1-5):1 to obtain a first solution; adding a template agent and concentrated hydrochloric acid to stir to obtain a second solution; adding manganese, titanium, cerium, niobium and additive precursors to stir to obtain a third solution; adding urea to stir to obtain a fourth solution; adding a hole expanding agent to stir to obtain a fifth solution; after reaction, washing and drying, the fifth solution is subjected to secondary reaction, washing and drying, and then is subjected to precalcination in an inert atmosphere and air calcination to obtain the amorphous denitration catalyst. The catalyst exhibits excellent denitration activity and stability under the conditions of containing liquid water and ammonium bisulfate.

Description

Technical Field

[0001] This invention relates to the field of selective catalytic reduction catalyst technology, and in particular to a method for preparing and applying an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning. Background Technology

[0002] Selective catalytic reduction (NH3-SCR) technology using ammonia as a reducing agent is currently the most widely used method for NO reduction. x Treatment methods. With increasingly stringent environmental protection requirements and the expansion of denitrification application scenarios, especially for non-electric industries such as steel and cement, as well as operating conditions such as aircraft engines and cold starts of motor vehicles, the exhaust gas temperature is often below 200℃ or even 100℃, which places extremely high demands on the low-temperature activity of denitrification catalysts.

[0003] Research on low-temperature SCR catalysts has become a current hot topic. Among them, Mn-based catalysts have attracted much attention due to their excellent low-temperature redox performance, especially the Mn-Ce / TiO2 series catalysts, which exhibit good catalytic activity in the temperature range of 100-250℃. Studies have shown that the introduction of Ce can effectively improve the catalytic activity of MnO2. x The N2 selectivity and sulfur resistance of TiO2 catalysts were studied. To further improve catalytic performance, researchers explored various modification strategies, including adding Nb, W, and other promoters, as well as optimizing the preparation method.

[0004] However, denitrification catalysts operating at ultra-low temperatures (<150℃) still face severe challenges. Firstly, flue gas typically contains water vapor, and at low temperatures, water molecules compete with reactants for adsorption, leading to a significant decrease in catalyst activity. More problematic is the reaction of SO2 with NH3 in the flue gas to form ammonium bisulfate (ABS). This substance readily deposits on the catalyst surface at low temperatures, covering active sites and clogging pores, causing irreversible catalyst deactivation. Simultaneously addressing the issues of low-temperature activity, water resistance, and resistance to ammonium bisulfate poisoning has become a key bottleneck restricting the application of ultra-low temperature SCR technology.

[0005] While existing research on Mn-Ce-Ti based catalysts has addressed improvements in sulfur resistance, effective technical solutions are still lacking for catalyst systems that exhibit both excellent water resistance and resistance to ammonium bisulfate poisoning under ultra-low temperature conditions. In particular, there are no systematic reports on simultaneously enhancing catalyst stability under conditions containing liquid water and ammonium bisulfate deposition through amorphous structure design and specific preparation process control.

[0006] In conclusion, developing a novel SCR catalyst that exhibits high activity, excellent water resistance, and resistance to ammonium bisulfate poisoning under ultra-low temperature (<150℃) conditions has significant application value and importance. Summary of the Invention

[0007] Based on the above analysis, the present invention aims to provide a method for preparing and applying an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, in order to solve the problem that existing low-temperature denitration catalysts are difficult to maintain high denitration activity, excellent water resistance and resistance to ammonium bisulfate poisoning under ultra-low temperature (<150℃) conditions, especially in complex atmospheres containing liquid water and ammonium bisulfate (ABS) deposits.

[0008] The objective of this invention is mainly achieved through the following technical solutions:

[0009] This invention provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0010] S1: Mix glacial acetic acid, anhydrous ethanol and ethylene glycol evenly to obtain the first solution;

[0011] S2: Add template agent and concentrated hydrochloric acid to the first solution in sequence, and stir magnetically at room temperature to obtain the second solution;

[0012] S3: Add the precursors of manganese, titanium, cerium, niobium and auxiliary agents to the second solution, and stir until they are mixed evenly to obtain the third solution;

[0013] S4: Add urea to the third solution and stir vigorously until the solution becomes clear and oily to obtain the fourth solution;

[0014] S5: Add the pore-expanding agent to the fourth solution and stir magnetically at room temperature until the pore-expanding agent is completely dissolved to obtain the fifth solution;

[0015] S6: The fifth solution is transferred to a high-pressure reactor lined with polytetrafluoroethylene and sealed. The reactor is then placed in a constant temperature oven for reaction to obtain the first product.

[0016] S7: After washing the first product until it is neutral, place it in a vacuum drying oven to dry it and obtain a dry powder;

[0017] S8: The dried first product is ultrasonically dispersed in ethanol to obtain a mixed solution. The mixed solution is then transferred to a reaction vessel for constant temperature reaction to obtain the second product.

[0018] S9: Centrifuge, wash, and separate the second product, and dry it in a vacuum drying oven to obtain the third product;

[0019] S10: The third product is placed in a tube furnace and calcined at a first specified temperature under an inert atmosphere, then switched to an air atmosphere and calcined at a second specified temperature to obtain an amorphous denitration catalyst.

[0020] Further, in step S1, the volume ratio of glacial acetic acid, anhydrous ethanol and ethylene glycol is (0.1-3):(1-5):1;

[0021] In step S2, the template agent is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer P123, and 0.9-3.5 g of P123 is added to every 40-80 mL of the first solution; and / or,

[0022] Add 0.5-4.5 g of concentrated hydrochloric acid to every 40-80 mL of the first solution.

[0023] Further, in step S3, the precursor of manganese is one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, or manganese perchlorate;

[0024] The titanium precursor is one of titanium tetrachloride, titanium oxysulfate, or titanate esters;

[0025] The precursor of cerium is cerium nitrate or cerium acetate;

[0026] The niobium precursor is one of niobium oxalate or niobium oxalate complex solution;

[0027] The precursor of the additive is one of the soluble salts of vanadium, tungsten, molybdenum, terbium, yttrium, or dysprosium.

[0028] Furthermore, in the manganese precursor, cerium precursor, and titanium precursor, the molar ratio of Mn, Ce, and Ti atoms is (0.4-1.3):1:(1-5); and / or,

[0029] In the niobium precursor and the titanium precursor, the molar ratio of Nb to Ti metal atoms is (0.02-0.05):1; and / or,

[0030] In the manganese precursor, cerium precursor, and auxiliary precursor, the atomic molar ratio of the auxiliary metal element to the total Mn and Ce elements is (0.01-0.05):1.

[0031] Further, in step S4, the amount of urea added is 5-15g of urea per 50-200 mL of the third solution.

[0032] Further, in step S5, the pore-expanding agent is an organic small-molecule swelling agent, which is one of trimethylbenzene, n-decane, triethylbenzene, triisopropylbenzene, xylene, or ethylbenzene; and / or,

[0033] The mass ratio of the pore-expanding agent to the template agent is (0.5-2):1.

[0034] Furthermore, in step S6, the reaction temperature is 80-100℃ and the reaction time is 14-48h;

[0035] In step S7, the drying temperature is 80-100℃ and the drying time is 6-12h;

[0036] In step S8, the ultrasonic dispersion power is 100-150W, and the ultrasonic time is 15-30 min; and / or,

[0037] The isothermal reaction is carried out at a temperature of 160-200℃ for 12-48 hours.

[0038] Further, in step S9, the vacuum degree of the drying oven is ≤0.1 MPa, the drying temperature is 80-100℃, and the drying time is 5-24h; and / or,

[0039] In step S10, the inert atmosphere is argon or nitrogen, the first specified temperature is 300-400℃, and the calcination time is 4-8h; the second specified temperature is 400-600℃, and the calcination time is 1-6h.

[0040] The present invention also provides an amorphous low-temperature denitrification catalyst resistant to water and ammonium bisulfate poisoning, prepared according to the above preparation method.

[0041] The present invention also provides the application of the low-temperature denitrification catalyst prepared according to the above preparation method in the denitrification of flue gas containing liquid water and / or containing ammonium bisulfate.

[0042] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0043] 1. The method of this invention involves mixing glacial acetic acid, anhydrous ethanol, and ethylene glycol in a specific volume ratio, then adding a template agent and concentrated hydrochloric acid and stirring. Subsequently, manganese, titanium, cerium, niobium, and auxiliary precursors are added sequentially to form a sol. Urea is added to adjust the system state, and a pore-expanding agent is added to control the pore structure. After a first-step solvothermal reaction, washing and drying, a second-step solvothermal reaction, and washing and drying again, the catalyst undergoes a two-step heat treatment of pre-calcination in an inert atmosphere and calcination in an air atmosphere to form an amorphous composite oxide catalyst with high specific surface area and suitable pore structure. The catalyst prepared by the method of this invention has good denitrification efficiency under liquid water conditions (e.g., water content of 5-15 vol%) and exhibits excellent catalytic activity and water resistance stability under ultra-low temperature (e.g., below 250℃) water-containing conditions.

[0044] 2. To address the technical problem of existing low-temperature denitration catalysts being easily deactivated in complex atmospheres containing ammonium bisulfate deposits, the preparation method of this invention utilizes the synergistic use of template agents and pore-expanding agents, a two-step solvothermal reaction, and a two-step calcination process involving an inert atmosphere followed by an air atmosphere. This process highly disperses Mn, Ce, Ti, Nb, and auxiliary components in the resulting catalyst, forming an amorphous structure. Simultaneously, it achieves a high specific surface area and suitable pore structure, thereby providing abundant redox sites and surface acidic sites. The catalyst prepared by this method exhibits excellent resistance to ammonium bisulfate poisoning.

[0045] 3. The preparation method of the present invention uses environmentally friendly elements such as manganese, cerium, and titanium as the main active components. The resulting catalyst does not contain toxic vanadium components, thus avoiding the secondary pollution problems that may occur during the application of vanadium-based catalysts. The preparation method of the present invention can achieve precise control of the pore structure and specific surface area of ​​the catalyst by adjusting parameters such as the volume ratio of glacial acetic acid, anhydrous ethanol, and ethylene glycol, the ratio of template agent to pore expander, the temperature and time of the first solvothermal reaction, the temperature and time of the second solvothermal reaction, and the temperature and time of the two calcinations. This is beneficial for mass production and performance stability.

[0046] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0047] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0048] Figure 1 The XRD patterns of the catalysts prepared in Examples 1-6 are shown below.

[0049] Figure 2 The XRD patterns of the catalysts prepared in Comparative Examples 1-3 are shown.

[0050] Figure 3 The image shows a SEM image of the composite catalyst prepared in Example 1.

[0051] Figure 4 This is a comparison chart of the NOx conversion rates of the catalysts in Example 1, Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3;

[0052] Figure 5 This is a comparison chart of the NOx conversion rates of the catalysts in Example 1 and Comparative Example 5;

[0053] Figure 6 This is a comparison chart of the NOx conversion rates of the catalysts in Example 2 and Comparative Example 2;

[0054] Figure 7 This is a comparison chart of the CO conversion rates of the catalysts in Example 2 and Comparative Example 2;

[0055] Figure 8 This is a comparison chart showing the resistance of the catalysts in Example 3 and Comparative Example 4 to ammonium bisulfate poisoning.

[0056] Figure 9 This is a comparison chart showing the resistance of the catalysts in Example 4 and Comparative Example 5 to ammonium bisulfate poisoning.

[0057] Figure 10 The graph shows the resistance of the catalyst to ammonium bisulfate poisoning in Example 5. Detailed Implementation

[0058] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0059] A method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning includes the following steps:

[0060] S1: Mix glacial acetic acid, anhydrous ethanol and ethylene glycol evenly to obtain the first solution;

[0061] Specifically, the volume ratio of glacial acetic acid, anhydrous ethanol, and ethylene glycol is (0.1-3):(1-5):1.

[0062] S2: Add template agent and concentrated hydrochloric acid to the first solution in sequence, and stir magnetically at room temperature to obtain the second solution;

[0063] Specifically, the template agent is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123). 0.9-3.5 g of P123 is added to every 40-80 mL of the first solution. This dosage ensures that the mass fraction of P123 in the system is within a suitable range for forming an ordered liquid crystal phase, which is more conducive to the formation of an ordered mesoporous structure. 0.5-4.5 g of concentrated hydrochloric acid is added to every 40-80 mL of the first solution. This dosage can fully protonate the P123 template agent, enhancing its structure-directing ability. The magnetic stirring speed is 500-1000 rpm (exemplarily, stirring speeds are 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm). The time is 1-3 hours (e.g., 1000 rpm, 1000 rpm), preferably 3 hours, to allow the template agent to be fully protonated.

[0064] S3: Add the precursors of manganese, titanium, cerium, niobium and auxiliary agents to the second solution, and stir until they are mixed evenly to obtain the third solution;

[0065] Specifically, the precursor of manganese is one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, or manganese perchlorate, preferably manganese nitrate; the precursor of titanium is one of titanium tetrachloride, titanium oxysulfate, or titanate esters, preferably tetrabutyl titanate; the precursor of cerium is cerium nitrate or cerium acetate, preferably cerium nitrate; the precursor of niobium is one of niobium oxalate or niobium oxalate complex solution; the precursor of the auxiliary agent is one of a soluble salt of vanadium, tungsten, molybdenum, terbium, yttrium, or dysprosium; wherein, the molar ratio of metal atoms of Mn, Ce, and Ti is (0.4-1.3):1:(1-5), and the amount of Mn and Ti is calculated proportionally based on the number of molar metal atoms of Ce; the molar ratio of metal atoms of Nb to Ti is (0.02-0.05):1; the molar ratio of the auxiliary agent metal element to the total of Mn and Ce elements is (0.01-0.05):1. The stirring speed is 500-1000 rpm (exemplary stirring speeds are 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, and 1000 rpm), and the stirring time is 5-10 hours (exemplary stirring times are 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, and 10 hours). Stir until the mixture is homogeneous to obtain a clear, transparent, uniformly colored sol without sediment.

[0066] S4: Add urea to the third solution and stir vigorously until the solution becomes clear and oily to obtain the fourth solution;

[0067] Specifically, 5-15g of urea is added to every 50-200 mL of the third solution. This ratio ensures the effective assembly of the subsequent catalyst structure. The stirring speed is 500-1500 rpm (exemplary stirring speeds are 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm, 1050 rpm, 1100 rpm, 1150 rpm, 1200 rpm, 1250 rpm, 1300 rpm, 1350 rpm, 1400 rpm, 1450 rpm). Stir for 1-2 hours (e.g., 1500 rpm, 1500 rpm) for 1-2 hours (e.g., 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.8 hours, 2 hours) until the solution becomes a transparent, clear, high-viscosity homogeneous oily liquid.

[0068] S5: Add the pore-expanding agent to the fourth solution and stir magnetically at room temperature until the pore-expanding agent is completely dissolved to obtain the fifth solution;

[0069] Specifically, the pore-expanding agent is an organic small-molecule swelling agent, specifically one of trimethylbenzene, n-decane, triethylbenzene, triisopropylbenzene, xylene, or ethylbenzene. The mass ratio of the pore-expanding agent to the template agent P123 added in step S2 is (0.5-2):1 (exemplarily, the mass ratio of the pore-expanding agent to the template agent is 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 1.9:1, or 2:1); the magnetic stirring speed is 500-1000 rpm (exemplarily, the stirring speed is 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, or 900 rpm). Stir at 950 rpm, 1000 rpm for 1-3 hours (exemplary times are 1 hour, 1.2 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.8 hours, and 3 hours) until the pore-expanding agent is completely dissolved, resulting in a clear, oil-drop-free suspension of the fifth solution.

[0070] S6: The fifth solution is transferred to a high-pressure reactor lined with polytetrafluoroethylene and sealed. The reactor is then placed in a constant temperature oven for reaction to obtain the first product.

[0071] Specifically, the high-pressure reactor operates under autogenous pressure, with a reaction temperature of 80-100℃ (exemplary values: 80℃, 85℃, 90℃, 95℃, 100℃) and a reaction time of 14-48 hours (exemplary values: 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h). Too low a temperature or too short a time will lead to incomplete reaction, while too high a temperature or too long a time will lead to excessive crystallization or structural coarsening, both of which are detrimental to obtaining the final high-performance catalyst. This step mainly involves the hydrolysis and condensation of the precursor and the self-assembly of the template agent P123, during which urea may decompose at high temperatures to produce ammonia, adjusting the pH.

[0072] S7: The first product is first washed with anhydrous ethanol, then washed with deionized water, and then dried in a vacuum drying oven to obtain a dry powder.

[0073] Specifically, the first product is washed a total of 3-5 times to remove template agents, pore expanders, unreacted ions, and byproducts. First, the first product is washed with ethanol to dissolve and remove organic template agents, pore expanders, and organic byproducts. Then, it is washed with deionized water to remove residual ethanol and water-soluble inorganic ions. A pH test showing the first product is neutral indicates sufficient washing. Vacuum drying reduces the damage to the structure caused by drying stress. The drying temperature is 80-100℃ (exemplary, 80℃, 85℃, 90℃, 95℃, 100℃), and the drying time is 6-12 hours (exemplary, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours). Too low a temperature or too short a time will result in incomplete drying, with residual solvent affecting subsequent steps. Too high a temperature or too long a time will cause premature decomposition or structural changes in the precursor.

[0074] S8: The dried first product is ultrasonically dispersed in ethanol to obtain a mixed solution. The mixed solution is then transferred to a polytetrafluoroethylene-lined reactor for constant-temperature reaction to obtain the second product.

[0075] Specifically, the ultrasonic dispersion power is 100-150W (exemplary values: 100W, 105W, 110W, 115W, 120W, 125W, 130W, 135W, 140W, 145W, 150W), and the ultrasonic dispersion time is 15-30min (exemplary values: 15min, 16min, 18min, 20min, 22min, 24min, 26min, 28min, 30min). The ultrasonic dispersion medium is anhydrous ethanol. Too low an ultrasonic power or too short a time will result in uneven dispersion, while too high an ultrasonic power or too long a time will damage the product structure. Ultrasonic dispersion is considered uniform when the solution is homogeneous and there are no visible lumps of precipitate. Immediately after ultrasonication, the mixed solution is transferred to a high-pressure reactor lined with polytetrafluoroethylene for constant-temperature reaction.

[0076] The isothermal reaction is carried out at a temperature of 160-200℃ (exemplary values: 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃, 200℃), for a reaction time of 12-48h (exemplary values: 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h), with the solution volume occupying 60%-80% of the reactor volume. Temperatures below 160℃ or reaction times shorter than 12h result in insufficient skeletal condensation and poor thermal stability of the product; temperatures above 200℃ or reaction times longer than 48h easily induce crystallization phase transformation or structural coarsening, leading to a significant decrease in specific surface area and destruction of the pore structure.

[0077] This step mainly involves further cross-linking, pore structure adjustment, and curing of the amorphous structure. The key role of this step in the final formation of an amorphous structure with high specific surface area and suitable pore size is that a controlled "skeleton ripening" and "pore shaping" process is carried out under relatively mild hydrothermal conditions. During the reaction process, metal-oxygen bonds are formed, template agents are further assembled, and partially removed.

[0078] S9: Centrifuge, wash, and separate the second product, and dry it in a vacuum drying oven to obtain the third product;

[0079] Specifically, this step mainly involves the physical removal of solvents and impurities. First, the second product is centrifuged, the supernatant is discarded, and the solid is obtained. The solid is washed with anhydrous ethanol, ultrasonically dispersed for 30 seconds, and then centrifuged again. This ethanol washing process is repeated three times. Then, deionized water is added for washing and centrifugation, and this water washing process is also repeated three times. Each time, the amount of solvent used is 3-5 times the volume of the solid. The final washed solid is placed in a vacuum drying oven with a vacuum degree ≤0.1 MPa, a drying temperature of 80-100℃ (exemplary, 80℃, 85℃, 90℃, 95℃, 100℃), and a drying time of 5-24h (exemplary, 5h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h). Drying at too low a temperature or for too short a time will result in incomplete drying, with residual solvent affecting subsequent steps. Drying at too high a temperature or for too long a time will cause premature decomposition of the precursor, partial decomposition of the template agent P123, or structural changes.

[0080] S10: The third product is placed in a tube furnace and calcined at a first specified temperature under an inert atmosphere, then switched to an air atmosphere and calcined at a second specified temperature to obtain an amorphous denitration catalyst.

[0081] Specifically, the first specified temperature is 300-400℃, the second specified temperature is 400-600℃, and the second specified temperature is greater than or equal to the first specified temperature; preferably, the first specified temperature is 350-380℃, and the second specified temperature is 480-550℃. The purpose of the first stage of low-temperature calcination under an inert atmosphere is to slowly remove the template agent and moisture, preliminarily decompose various metal salts, protect the pore structure, and prevent sintering; the purpose of the second stage of high-temperature calcination under an air atmosphere is to complete the crystal phase transformation, enhance the metal-support interaction, and ensure the stability of the active phase structure. This invention limits the second specified temperature to be greater than or equal to the first specified temperature to ensure the sequence of low-temperature carbonization followed by high-temperature oxidation, which protects the pore structure from being destroyed by violent combustion and ensures the complete removal of carbon residues and sufficient densification of the skeleton.

[0082] Specifically, the third product is placed in a tube furnace and calcined at a first specified temperature under an argon or nitrogen atmosphere. The heating rate is 1-5℃ / min (exemplary: 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, 5℃ / min), the first specified temperature is 300-400℃ (exemplary: 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃, 400℃), the calcination time is 4-8h (exemplary: 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h), and the inert gas flow rate is 50-200... The heating rate is set at mL / min (exemplary rates: 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, 110 mL / min, 120 mL / min, 130 mL / min, 140 mL / min, 150 mL / min, 160 mL / min, 170 mL / min, 180 mL / min, 190 mL / min, 200 mL / min). A slow heating rate of 1-5 °C / min avoids thermal shock. A temperature of 300-400 °C provides a window to ensure sufficient decomposition and carbonization of the organic matter while the metal framework has not yet significantly crystallized. Calcination for 4-8 hours ensures complete pyrolysis. The purpose of this stage is to allow the residual trace amounts of organic matter such as P123 in the precursor to undergo slow pyrolysis and carbonization in an anaerobic environment, rather than vigorous oxidative combustion.

[0083] Then, the atmosphere is switched to air, and calcination is carried out at a second specified temperature. The heating rate is 1-5℃ / min (exemplary, 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, 5℃ / min), the second specified temperature is 400-600℃ (exemplary, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃), and the calcination time is 1-6h (exemplary, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h), to obtain an amorphous denitrification catalyst. The purpose of this stage is to completely oxidize and remove residual carbonaceous species, further condense and densify the amorphous metal oxide framework under aerobic conditions, and ultimately achieve structural stability. The order of the two calcinations is first in an inert atmosphere and then in an air atmosphere. If the order is reversed, the organic matter will burn violently in air, which can easily destroy the structure and ultimately lead to a low specific surface area and poor activity of the catalyst.

[0084] The method of this invention involves mixing glacial acetic acid, anhydrous ethanol, and ethylene glycol in a specific volume ratio, then adding a template agent and concentrated hydrochloric acid and stirring. Subsequently, manganese, titanium, cerium, niobium, and auxiliary precursors are added sequentially to form a sol. Urea is added to adjust the system state, and a pore-expanding agent is added to control the pore structure. After a first-step solvothermal reaction, washing and drying, a second-step solvothermal reaction, and washing and drying again, a two-step heat treatment of pre-calcination in an inert atmosphere and calcination in an air atmosphere is performed to form an amorphous composite oxide catalyst with high specific surface area and suitable pore structure. The catalyst prepared by this invention has good denitrification efficiency under liquid water conditions and exhibits excellent catalytic activity and water resistance stability under ultra-low temperature water-containing conditions.

[0085] The catalyst prepared in this invention has a specific surface area ranging from 90 to 120 m². 2 / g, average pore size 5.50-7.90nm, pore volume 0.10-0.50cm³ 3 / g. This structural feature provides abundant surface active sites and good reactant diffusion channels for catalytic reactions, which is the key structural basis for its excellent low-temperature activity and anti-poisoning properties.

[0086] The catalyst prepared in this invention exhibits excellent catalytic performance and resistance to poisoning under complex industrial flue gas conditions simulating liquid water and ammonium bisulfate deposition. The catalyst shows good NO reduction within a temperature range of 66-200℃. x Conversion rate greater than 80%; CO conversion rate greater than 80% within the temperature range of 67-120℃; Antitoxicity test of catalyst loaded with 10% ABS showed that the catalyst exhibited NO conversion rate greater than 80% at 150-300℃. x Conversion rate greater than or equal to 90%.

[0087] The catalyst prepared in this invention has an amorphous structure, exhibiting a nanoscale multiphase structure. The main body is a dense, dark-gray continuous matrix with uniformly distributed particle sizes ranging from 10 to 30 nm, forming a porous or sponge-like network. The overall morphology is a high specific surface area nanoporous stacked structure, without obvious large pores or cracks, exhibiting a dense structure while retaining a certain porosity.

[0088] The ignition temperature (T) of the catalyst prepared in this invention 50 Below 125 ℃, in the low temperature range of 125-150 ℃, NO x With a conversion rate of ≥80%, it exhibits excellent low-temperature activity; it can stably maintain over 90% NO conversion within a wide temperature range of 125–250 °C. x It exhibits outstanding conversion rate and activity stability.

[0089] The catalyst prepared in this invention, under 5% H2O conditions, produces NO within a wide temperature range of 70–200 °C. xThe conversion rate remained relatively stable at over 80%; in terms of CO oxidation performance, the CO conversion rate remained above 80% within the range of 68-110℃ (100% at 70~100℃).

[0090] The catalyst prepared in this invention was poisoned by impregnation with an equal volume of 10% ammonium bisulfate solution in an atmosphere containing 5% H2O. Within a low-temperature range of 150℃-225℃, NO... x Conversion rate ≥ 90%.

[0091] Example 1

[0092] This embodiment provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0093] S1: Mix 6 mL of glacial acetic acid, 50 mL of anhydrous ethanol and 10 mL of ethylene glycol until homogeneous to obtain the first solution;

[0094] S2: Add template agent and concentrated hydrochloric acid to the first solution in sequence, and stir magnetically at room temperature to obtain the second solution;

[0095] Specifically, the template agent is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123); 1g of P123 and 2g of hydrochloric acid are added to every 65 mL of the first solution. The magnetic stirring speed is 1000 rpm, and the stirring time is 1 hour.

[0096] S3: Add the precursors of manganese, titanium, cerium, niobium and auxiliary agents to the second solution, and stir until they are mixed evenly to obtain the third solution;

[0097] The manganese precursor is a 50% manganese nitrate (Mn(NO3)2) solution, and the amount added is 5.184g.

[0098] The precursor of titanium is tetrabutyl titanate (C 16 H 36 O4Ti), the amount added was 7.668g;

[0099] The cerium precursor is cerium nitrate hexahydrate (Ce(NO3)3·6H2O), and the amount added is 4.892g;

[0100] The precursor of niobium is niobium oxalate (C 10 H5NbO 20 The amount added is 0.300g;

[0101] The precursor for the auxiliary agent is ammonium metatungstate ((NH4)). 10 H2W 12 O 42·xH2O), the amount added was 0.213g;

[0102] The molar ratio of Mn, Ce and Ti atoms is 1.28:1:2. Based on the molar number of Ce atoms of 0.0113 mol, the sample weight of Mn and Ti precursors is calculated. The molar ratio of Nb to Ti atoms is 0.0248:1. The molar ratio of the auxiliary metal elements to the total of Mn and Ce elements is 0.0324:1.

[0103] The stirring speed was 1000 rpm and the stirring time was 9 hours. The mixture was stirred until it was homogeneous, resulting in a clear, transparent sol with uniform color and no sediment.

[0104] S4: Add urea to the third solution and stir vigorously until the solution becomes clear and oily to obtain the fourth solution;

[0105] Specifically, add 6g of urea to every 70 mL of the third solution, stir at 1000 rpm for 1.5 hours, and stir until the solution becomes a transparent, high-viscosity, homogeneous oily liquid.

[0106] S5: Add the pore-expanding agent to the fourth solution and stir magnetically at room temperature until the pore-expanding agent is completely dissolved to obtain the fifth solution;

[0107] Specifically, the pore-expanding agent is trimethylbenzene, and the amount added is 1g. The mass ratio of the pore-expanding agent to the template agent P123 is 1:1. The magnetic stirring speed is 1000 rpm, and the magnetic stirring time is 1h. The mixture is stirred until the pore-expanding agent is completely dissolved, resulting in a clear, oil-drop-free suspension of the fifth solution.

[0108] S6: The fifth solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and sealed. The reactor was then placed in a constant temperature oven for reaction at 100°C for 24 hours to obtain the first product.

[0109] S7: The first product was first washed with anhydrous ethanol, then washed with deionized water, for a total of 3 washes, and then placed in a vacuum drying oven and dried at 80°C for 12 hours to obtain a dry powder.

[0110] S8: The dried first product is ultrasonically dispersed in ethanol to obtain a mixed solution. The mixed solution is then transferred to a polytetrafluoroethylene-lined reactor for constant-temperature reaction to obtain the second product.

[0111] Specifically, the ultrasonic dispersion power is 100W, the ultrasonic time is 20min, the constant temperature reaction temperature is 160℃, the reaction time is 12h, and the solution volume accounts for 60% of the reaction vessel volume.

[0112] S9: Centrifuge, wash, and separate the second product, and dry it in a vacuum drying oven to obtain the third product;

[0113] Specifically, the second product was first centrifuged, the supernatant was discarded, and the solid was washed with anhydrous ethanol, ultrasonically dispersed for 30 seconds, and then centrifuged again. This ethanol washing process was repeated three times. Afterward, deionized water was added for washing and centrifugation, and this water washing process was also repeated three times. Each time, the solvent volume was 3-5 times the volume of the solid. The final washed solid was placed in a vacuum drying oven at a vacuum level of 0.08 MPa, a drying temperature of 80℃, and a drying time of 8 hours.

[0114] S10: The third product is placed in a tube furnace and calcined at a first specified temperature under an inert atmosphere, then switched to an air atmosphere and calcined at a second specified temperature to obtain an amorphous denitration catalyst.

[0115] Specifically, the third product is placed in a tube furnace and calcined at a first specified temperature under an argon atmosphere, wherein the heating rate is 1℃ / min, the first specified temperature is 350℃, the calcination time is 4h, and the argon flow rate is 80 mL / min.

[0116] Then, the atmosphere was switched to air, and the catalyst was calcined at a second specified temperature, wherein the heating rate was 1℃ / min, the second specified temperature was 400℃, and the calcination time was 5h, to obtain an amorphous denitrification catalyst.

[0117] Example 2

[0118] This embodiment provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0119] S1: Mix 5 mL of glacial acetic acid, 50 mL of anhydrous ethanol and 10 mL of ethylene glycol until homogeneous to obtain the first solution; (volume ratio approximately 0.2:5:1, different from Example 1)

[0120] S2: Same as Example 1;

[0121] S3: Same as Example 1;

[0122] S4: Add urea to the third solution and stir vigorously until the solution becomes clear and oily to obtain the fourth solution;

[0123] Specifically, add 8g of urea to every 70 mL of the third solution, stir at 1000 rpm for 1.5 hours, and stir until the solution becomes a transparent, high-viscosity, homogeneous oily liquid.

[0124] S5: Same as Example 1;

[0125] S6: Same as Example 1;

[0126] S7: Same as Example 1;

[0127] S8: Same as Example 1;

[0128] S9: Same as Example 1;

[0129] S10: Calcination at a second specified temperature of 500℃ for 1 hour yields an amorphous denitrification catalyst, with the remainder being the same as in Example 1.

[0130] Example 3

[0131] This embodiment provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0132] S1: Mix 6 mL of glacial acetic acid, 30 mL of anhydrous ethanol, and 30 mL of ethylene glycol thoroughly to obtain the first solution; (volume ratio approximately 0.2:1:1, different from Example 1)

[0133] S2: Add template agent and concentrated hydrochloric acid to the first solution in sequence, and stir magnetically at room temperature to obtain the second solution;

[0134] Specifically, the template agent is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123); 1g of P123 and 2g of hydrochloric acid are added to every 66 mL of the first solution. The magnetic stirring speed is 1000 rpm, and the magnetic stirring time is 1 hour.

[0135] S3: Same as Example 1;

[0136] S4: Same as Example 1;

[0137] S5: Same as Example 1;

[0138] S6: The fifth solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and sealed. The reactor was then placed in a constant temperature oven for reaction at 80°C for 24 hours to obtain the first product.

[0139] S7: The first product is first washed with anhydrous ethanol, then washed with deionized water, for a total of 3 washes, and then placed in a vacuum drying oven and dried at 100°C for 6 hours to obtain a dry powder.

[0140] S8: Same as Example 1;

[0141] S9: Same as Example 1;

[0142] S10: Same as Example 1.

[0143] Example 4

[0144] This embodiment provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0145] S1: Same as Example 1;

[0146] S2: Add template agent and concentrated hydrochloric acid to the first solution in sequence, and stir magnetically at room temperature to obtain the second solution;

[0147] Specifically, the template agent is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123); 1 g of P123 and 2 g of hydrochloric acid are added to every 46 mL of the first solution. The magnetic stirring speed is 1000 rpm, and the magnetic stirring time is 1 h.

[0148] S3: Same as Example 1;

[0149] S4: Add urea to the third solution and stir vigorously until the solution becomes clear and oily to obtain the fourth solution;

[0150] Specifically, add 6g of urea to every 50 mL of the third solution, stir at 1000 rpm for 1.5 hours, and stir until the solution becomes a transparent, high-viscosity, homogeneous oily liquid.

[0151] S5: Same as Example 1;

[0152] S6: The fifth solution was transferred to a high-pressure reactor lined with polytetrafluoroethylene and sealed. The reactor was then placed in a constant temperature oven for reaction at 100°C for 36 hours to obtain the first product.

[0153] S7: Same as Example 1;

[0154] S8: Same as Example 1;

[0155] S9: Same as Example 1;

[0156] S10: Same as Example 1.

[0157] Example 5

[0158] This embodiment provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0159] S1: Same as Example 1;

[0160] S2: Same as Example 4;

[0161] S3: Same as Example 1;

[0162] S4: Same as Example 4;

[0163] S5: Add the pore-expanding agent to the fourth solution and stir magnetically at room temperature until the pore-expanding agent is completely dissolved to obtain the fifth solution;

[0164] Specifically, the pore-expanding agent is trimethylbenzene, with an addition amount of 2g. The mass ratio of the pore-expanding agent to the template agent P123 is 2:1. The magnetic stirring speed is 500 rpm, and the magnetic stirring time is 3h. The mixture is stirred until the pore-expanding agent is completely dissolved, resulting in a clear, oil-drop-free suspension of the fifth solution.

[0165] S6: Same as Example 4;

[0166] S7: Same as Example 1;

[0167] S8: Same as Example 1;

[0168] S9: Same as Example 1;

[0169] S10: Same as Example 1.

[0170] Example 6

[0171] This embodiment provides a method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, comprising the following steps:

[0172] S1: Same as Example 1;

[0173] S2: Same as Example 1;

[0174] S3: Same as Example 1;

[0175] S4: Same as Example 1;

[0176] S5: Same as Example 1;

[0177] S6: Same as Example 1;

[0178] S7: Same as Example 1;

[0179] S8: After ultrasonically dispersing the dry powder, react at 180°C for 10 hours, and the rest is the same as in Example 1;

[0180] S9: Same as Example 1;

[0181] S10: Calcination at a second specified temperature of 450℃ for 2.5h yields an amorphous denitrification catalyst, with the remainder being the same as in Example 1.

[0182] Comparative Example 1

[0183] This comparative example uses a traditional co-precipitation method to prepare a denitrification catalyst, including the following steps:

[0184] S1: Dissolve 5.184 g of 50 wt% manganese nitrate solution, 4.892 g of cerium nitrate hexahydrate, 0.300 g of niobium oxalate, and 0.213 g of ammonium metatungstate in 30 mL of deionized water and stir for 30 min;

[0185] S2: Slowly add 7.668 g of tetrabutyl titanate and continue stirring for 1 hour;

[0186] S3: Add 1 g of P123 (same as the template agent in the example) dropwise, and continue stirring for 1 hour;

[0187] S4: Adjust the pH to approximately 11 using concentrated ammonia;

[0188] S5: Aging at 100℃ for 24 hours in a homogeneous reactor;

[0189] S6: Wash three times with deionized water and dry at 110℃ for 12 hours;

[0190] S7: Calcine in air at 500℃ for 1 hour to obtain the catalyst.

[0191] Comparative Example 2

[0192] This comparative example provides a method for preparing a denitrification catalyst, with steps similar to those in Example 1, except that step S4 is as follows:

[0193] S4: Adjust the pH to approximately 9.5 with ammonia and stir for 2 hours (instead of adding urea).

[0194] The remaining steps are the same as in Example 1.

[0195] Comparative Example 3

[0196] This comparative example provides a method for preparing a denitrification catalyst, with steps similar to those in Example 1, except that step S2 is as follows:

[0197] S2: Add 2 g of concentrated hydrochloric acid directly (without adding P123);

[0198] The remaining steps are the same as in Example 1, and the catalyst is obtained.

[0199] Comparative Example 4

[0200] This comparative example provides a method for preparing a denitration catalyst, which is similar to the steps in Example 1, except that:

[0201] S5: No pore expander added.

[0202] The remaining steps are the same as in Example 1, and the catalyst is obtained.

[0203] Comparative Example 5

[0204] This comparative example provides a method for preparing a denitrification catalyst, prepared according to the steps of Example 1, with the difference being:

[0205] S6: After sealing the fifth solution, place it in a constant temperature oven at 140°C and react for 24 hours to obtain the first product;

[0206] S8: The dried first product is ultrasonically dispersed in ethanol to obtain a mixed solution. The mixed solution is then transferred to a polytetrafluoroethylene-lined reactor for constant-temperature reaction to obtain the second product.

[0207] Specifically, the ultrasonic power is 100W, the ultrasonic time is 20min, the constant temperature reaction temperature is 220℃, and the reaction time is 12h.

[0208] The remaining steps are the same as in Example 1, and the catalyst is obtained.

[0209] The denitration catalysts prepared in the examples and comparative examples were characterized and their performance tested as follows:

[0210] The crystal structure of the catalysts was analyzed by X-ray powder diffraction (XRD) using a Dutch X-pert powder diffractometer. The XRD patterns of the catalysts in Examples 1-6 and Comparative Examples 1-3 are shown below. Figure 1 and Figure 2 As shown.

[0211] The XRD patterns of the catalysts in Examples 1-6 are as follows: Figure 1 As shown, from Figure 1 It can be seen that the XRD patterns of Examples 1-6 all exhibit broad diffraction peaks in the range of 2θ from 10° to 50°, without obvious sharp diffraction peaks of crystalline phases, confirming that the catalysts prepared in Examples 1-6 have an amorphous structure. XRD patterns of Comparative Examples 1-3 ( Figure 2 Multiple characteristic diffraction peaks appear in the sample (as shown), corresponding to the crystalline CeO2 (PDF#43-1002) structure, which contrasts sharply with the amorphous structure of the catalysts in Examples 1-6, demonstrating the advantages of the embodiments of the present invention in achieving amorphous state control.

[0212] The specific surface area, pore volume, and pore size of the catalyst were determined using a Micromeritics ASAP 2460 physical adsorption instrument. Before the test, the sample was degassed at 105℃ for 2 hours. The results were taken as the average of three tests and are shown in Table 1.

[0213] The catalyst morphology was observed using a field emission scanning electron microscope (Sigma 500, Zeiss). A 60-second Pt sputtering treatment was performed before testing. The SEM image for Example 1 is shown below. Figure 3 As shown.

[0214] Figure 3This is the SEM image of Example 1. Figure 3 The catalyst prepared in Example 1 exhibits a nanoscale multiphase structure, with a dense, dark gray continuous matrix as the main body. The particle size is uniformly distributed in the range of 10–30 nm, forming a porous or sponge-like network. The overall morphology is a high specific surface area nanoporous stacked structure, without obvious large-sized pores or cracks, and the structure is dense while retaining a certain porosity.

[0215] Table 1. Texture properties of catalysts in the examples and comparative examples.

[0216]

[0217] The catalysts in Examples 1-2, Comparative Examples 1-3, and Comparative Example 5 were tested for activity. 0.45 g of the prepared catalyst (40-60 mesh) was loaded into a fixed-bed quartz reactor with an inner diameter of 6 mm for NH3-SCR activity testing. The reaction mixture consisted of 500 ppm NO, 500 ppm NH3, 10% O2, and 5% H2O, with N2 in equilibrium. The total gas flow rate was 750 mL / min, and the gas space velocity (GHSV) was 100,000 h⁻¹. -1 The FTIR spectrometer in Antaris IGS (Thermo Scientific) was used to test the spectra at standard atmospheric pressure in the range of 100–350 nm. o The gas concentration at temperature C is measured for nitrogen oxides (NOx). x The conversion rate is calculated according to Formula 1.

[0218] Formula 1

[0219] Combination Figure 4-5 It can be seen that the denitrification activity of the amorphous catalysts synthesized in Examples 1 and 2 is significantly better than that of the catalysts synthesized in Comparative Examples 1-3 and Comparative Example 5. Combined with... Figure 4-5 It can be seen that the ignition temperature (T) of the catalyst of this invention is... 50 Below 125 °C, the optimal embodiment (Example 1) shows NO at 100 °C. x The conversion rate is close to 100%, exhibiting excellent low-temperature activity; the ignition temperatures of Comparative Examples 1-3 and Comparative Example 5 are significantly delayed. Regarding the activity window, the catalyst prepared in this invention can stably maintain over 90% NO concentration over a wide temperature range of 125–250 °C. x The conversion rate and activity stability were outstanding; while the comparative examples generally had a narrower activity window, such as Comparative Example 1, which only showed NO activity in the range of 225–250 °C. x The conversion rate reaches 90%, but the activity in the low-temperature section is insufficient, making it difficult to meet the application requirements of low-temperature denitrification engineering.

[0220] To test whether the catalysts could meet the emission requirements of aero-engines, the catalysts in Example 2 and Comparative Example 2 were subjected to activity tests. 0.45 g of the prepared 40-60 mesh catalyst was loaded into a fixed-bed quartz reactor with an inner diameter of 6 mm for NH3-SCR activity testing. The reaction mixture consisted of 20 ppm NO, 20 ppm NH3, 20% O2, 61 ppm CO, and 4% H2O, with N2 in equilibrium. The total gas flow rate was 750 mL / min, and the gas space-time velocity (GHSV) was 100,000 h⁻¹. -1 The FTIR spectrometer in Antaris IGS (Thermo Scientific) was used to test the spectra at standard atmospheric pressure in the range of 50-200 μm. o The gas concentration at temperature C is measured for nitrogen oxides (NOx). x The conversion rate of ) is calculated according to Formula 1, and the conversion rate of carbon monoxide (CO) is calculated according to Formula 2.

[0221] Formula 2

[0222] Combination Figure 6-7 It can be seen that, under test conditions containing liquid water, the denitrification activity and CO oxidation activity of the amorphous catalyst synthesized in Example 2 are significantly better than those of Comparative Example 2.

[0223] Combination Figure 6-7 Test data under 5% H2O conditions showed that the catalyst of Example 2 of this invention significantly outperformed Comparative Example 2 in terms of low-temperature activity and water resistance. Regarding denitrification performance, Example 2 showed better NO reduction performance over a wide temperature range of 70–200 °C. x The conversion rate remained consistently above 80% (89% at 150 °C, and 100% at all other temperature points); while Comparative Example 2 only reached 100% at 70 °C, with conversion rates below 60% at other temperature points. Regarding CO oxidation performance, Example 2 maintained a CO conversion rate consistently above 80% within the range of 68-110 °C (100% at 70-100 °C), while Comparative Example 2 essentially lost its oxidizing activity above 80 °C.

[0224] To further investigate the catalyst's resistance to ammonium bisulfate poisoning, the catalysts from Examples 3-5 and Comparative Examples 4-5 were loaded with ammonium bisulfate (ABS). Specifically, 0.2 g of ammonium bisulfate was dissolved in deionized water, and then 2 g of the prepared catalyst was impregnated in the solution using an equal-volume impregnation method. Subsequently, the samples were dried in an oven at 105 °C, and the resulting catalysts were subjected to activity testing. 0.45 g of the prepared 40-60 mesh catalyst was loaded into a fixed-bed quartz reactor with an inner diameter of 6 mm for NH3-SCR activity testing. The reaction mixture consisted of 500 ppm NO, 500 ppm NH3, 10% O2, and 5% H2O, with N2 in equilibrium. The total gas flow rate was 750 mL / min, and the gas space-time velocity (GHSV) was 100,000 h⁻¹. -1 The FTIR spectrometer in Antaris IGS (Thermo Scientific) was used to test the spectra at standard atmospheric pressure in the range of 100–350 nm. o The gas concentration at temperature C is measured for nitrogen oxides (NOx). x The conversion rate is calculated according to Formula 1. Figure 8-9 As can be seen from this, the synthesis catalyst has excellent resistance to ammonium bisulfate poisoning.

[0225] The catalyst samples of Examples 3, 4, 5 and Comparative Examples 4 and 5 were poisoned by being impregnated with an equal volume of 10% ammonium bisulfate solution in an atmosphere containing 5% H2O, and then their activity was tested in the range of 150~300℃.

[0226] Figure 8 Test results show that the catalysts of Example 3 and Comparative Example 4, in their fresh state, have a low NO content. x The conversion rate gradually increased with increasing reaction temperature, reaching 100% and remaining stable after 225℃. Following ABS poisoning treatment, the NO in Example 3 showed good conversion rates within a low-temperature range of 150℃ to 225℃. x The conversion rate was significantly higher than that of Comparative Example 4, indicating that Example 3 of the present invention has superior low-temperature resistance to ABS poisoning.

[0227] Figure 9 Test results show that the catalysts of Example 4 and Comparative Example 5, in their fresh state, have a low NO content. x The conversion rate gradually increased with increasing reaction temperature, and remained stable after 225℃. After ABS poisoning treatment, in Example 4, NO was reduced within a low temperature range of 150~225℃. x The conversion rate remained above 85%, while in Comparative Example 5, the conversion rate only approached 85% after reaching 240°C. These results fully demonstrate that Example 4 of the present invention exhibits significantly superior ABS poisoning performance at low temperatures.

[0228] Figure 10 The test results show that, in the fresh state, the NOx conversion rates of both Example 5 and Comparative Example 5 catalysts gradually increased with increasing reaction temperature and remained stable after 200°C. After ABS poisoning treatment, the NOx conversion rate of Example 5 remained stable within the low-temperature range of 150~200°C. x The conversion rate remained better than the control group by 5.

[0229] As can be seen from the above analysis, the rare earth composite catalyst synthesized in this invention has excellent denitrification performance and resistance to water and ammonium sulfate poisoning.

[0230] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, characterized in that, Includes the following steps: S1: Mix glacial acetic acid, anhydrous ethanol and ethylene glycol evenly to obtain the first solution; S2: Add template agent and concentrated hydrochloric acid to the first solution in sequence, and stir magnetically at room temperature to obtain the second solution; S3: Add the precursors of manganese, titanium, cerium, niobium and auxiliary agents to the second solution, and stir until they are mixed evenly to obtain the third solution; S4: Add urea to the third solution and stir vigorously until the solution becomes clear and oily to obtain the fourth solution; S5: Add the pore-expanding agent to the fourth solution and stir magnetically at room temperature until the pore-expanding agent is completely dissolved to obtain the fifth solution; S6: The fifth solution is transferred to a high-pressure reactor lined with polytetrafluoroethylene and sealed. The reactor is then placed in a constant temperature oven for reaction to obtain the first product. S7: After washing the first product until it is neutral, place it in a vacuum drying oven to dry it and obtain a dry powder; S8: The dried first product is ultrasonically dispersed in ethanol to obtain a mixed solution. The mixed solution is then transferred to a reaction vessel for constant temperature reaction to obtain the second product. S9: Centrifuge, wash, and separate the second product, and dry it in a vacuum drying oven to obtain the third product; S10: The third product is placed in a tube furnace and calcined at a first specified temperature under an inert atmosphere. Then, the atmosphere is switched to air and calcined at a second specified temperature to obtain an amorphous denitration catalyst. In step S2, the template agent is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer P123. In step S5, the pore-expanding agent is an organic small molecule swelling agent, which is one of trimethylbenzene, n-decane, triethylbenzene, triisopropylbenzene, xylene, or ethylbenzene. In step S6, the reaction temperature is 80-100℃ and the reaction time is 14-48h; In step S8, the temperature of the isothermal reaction is 160-200℃, and the reaction time is 12-48h; In step S1, the volume ratio of glacial acetic acid, anhydrous ethanol and ethylene glycol is (0.1-3):(1-5):1; In step S3, the auxiliary precursor is one of the soluble salts of vanadium, tungsten, molybdenum, terbium, yttrium, or dysprosium; in the manganese precursor, cerium precursor, and auxiliary precursor, the atomic molar ratio of the auxiliary metal element to the total Mn and Ce elements is (0.01-0.05):

1. In step S10, the inert atmosphere is argon or nitrogen, the first specified temperature is 300-400℃, and the calcination time is 4-8h; the second specified temperature is 400-600℃, and the calcination time is 1-6h.

2. The preparation method according to claim 1, characterized in that, In step S2, 0.9-3.5 g of P123 is added to every 40-80 mL of the first solution; and / or, Add 0.5-4.5 g of concentrated hydrochloric acid to every 40-80 mL of the first solution.

3. The preparation method according to claim 1, characterized in that, In step S3, the precursor of manganese is one of manganese sulfate, manganese chloride, manganese nitrate, manganese acetate, or manganese perchlorate; The titanium precursor is one of titanium tetrachloride, titanium oxysulfate, or titanate esters; The precursor of cerium is cerium nitrate or cerium acetate; The precursor of niobium is either niobium oxalate or a niobium oxalate complex solution.

4. The preparation method according to claim 3, characterized in that, In the manganese precursor, cerium precursor, and titanium precursor, the molar ratio of Mn, Ce, and Ti atoms is (0.4-1.3):1:(1-5); and / or, In the niobium precursor and the titanium precursor, the molar ratio of Nb to Ti metal atoms is (0.02-0.05):

1.

5. The preparation method according to claim 1, characterized in that, In step S4, the amount of urea added is 5-15g of urea per 50-200 mL of the third solution.

6. The preparation method according to claim 1, characterized in that, In step S5, The mass ratio of the pore-expanding agent to the template agent is (0.5-2):

1.

7. The preparation method according to claim 1, characterized in that, In step S7, the drying temperature is 80-100℃ and the drying time is 6-12h; In step S8, the ultrasonic dispersion power is 100-150W and the ultrasonic time is 15-30 min.

8. The preparation method according to claim 1, characterized in that, In step S9, the vacuum degree of the drying oven is ≤0.1MPa, the drying temperature is 80-100℃, and the drying time is 5-24h.

9. An amorphous low-temperature denitration catalyst resistant to water and ammonium bisulfate poisoning, characterized in that, Prepared according to any one of claims 1-8.

10. The application of the amorphous low-temperature denitrification catalyst prepared by the preparation method according to any one of claims 1-8 or the amorphous low-temperature denitrification catalyst according to claim 9 in the denitrification of flue gas containing liquid water and / or containing ammonium bisulfate.

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