Method for modifying and regenerating a deactivated denitration catalyst

Abstract

A method for modifying and regenerating deactivated denitration catalysts belongs to the field of denitration catalyst regeneration. First, the deactivated catalyst is broken down into uniform block-shaped units. Surface dust is removed by high-pressure gas purging, followed by ultrasonic chemical cleaning. The cleaned catalyst is then immersed in regeneration solution A at a controlled temperature. After immersion, it is dried and subjected to sulfidation treatment. The sulfidated catalyst is then immersed in regeneration solution B at a controlled temperature. Finally, the catalyst is calcined to complete the modification and regeneration. This method uses a sol-gel method to fully disperse cerium nitrate components in colloidal form on the catalyst surface. Simultaneously, citric acid forms high specific surface area carbon during drying, expanding the catalyst's specific surface area. Sulfidation treatment improves the denitration performance of the cerium components on the catalyst surface, and combined with vanadium on the catalyst surface, effectively enhances the activity of the regenerated catalyst in combined denitration and mercury removal, broadening the application range of regenerated denitration catalysts.

Description

Technical Field

[0001] This invention relates to a method for modifying and regenerating a deactivated denitrification catalyst, belonging to the field of SCR denitrification catalyst regeneration and utilization. Background Technology

[0002] Selective catalytic reduction (SCR) is a technology that primarily uses denitrification catalysts as carriers in conjunction with NH3 to remove nitrogen oxides from gases. Many industries, particularly thermal power plants, emit high levels of nitrogen oxides, and these industries extensively utilize denitrification catalysts to remove nitrogen oxides from their exhaust gases.

[0003] The most widely used denitrification catalyst in China is the vanadium-titanium catalyst, which uses titanium dioxide as a carrier and whose main active components are vanadium pentoxide and tungsten trioxide. Its service life is generally 2 to 3 years. In recent years, due to various reasons, a large number of deactivated denitrification catalysts have been deactivated and urgently need to be treated. As waste SCR denitrification catalysts are listed as hazardous waste in the "National Hazardous Waste List", it is encouraged to regenerate or safely treat them. Denitrification catalysts that can be regenerated after chemical and physical analysis should be regenerated to achieve the recycling of denitrification catalysts.

[0004] Patent CN114471746A discloses a method for regenerating SCR denitration catalysts. This method involves impregnating a deactivated catalyst in a replenishing solution, reacting it with ammonia, neutralizing it, hydrolyzing it, and then calcining it to obtain a regenerated SCR denitration catalyst. This method not only allows for the recycling and reuse of spent catalysts, but also allows the extracted active components to be directly used in the regeneration process of the deactivated catalyst. Simultaneously, the replenished support components improve the mechanical strength of the regenerated catalyst. However, the regenerated denitration catalyst has a narrow application range and poor dispersion of active components, limiting its reuse to the same locations as before regeneration.

[0005] Patent CN107597139B discloses a mercury removal synergistic denitrification catalyst and its preparation method. This method involves loading iron salts, manganese salts, and cerium salts onto graphene oxide in a specific ratio using a hydrothermal method, followed by drying and calcination under a nitrogen atmosphere to obtain the mercury removal synergistic denitrification catalyst. However, this method consumes a large amount of metal salts, uses graphene as a support, and is expensive and economically inefficient. Furthermore, the graphene support is prone to delamination and structural changes during long-term use, and the resulting carbon deposits can easily clog reactive sites, making it unsuitable for large-scale production.

[0006] Patent CN104815674A discloses a modified regenerated solution for combined denitration and mercury removal of a deactivated vanadium-titanium-based honeycomb denitration catalyst and its preparation method. This method uses a mixture of ammonium metavanadate, ammonium metatungstate, oxalic acid, cerium nitrate, copper chloride, and deionized water to prepare the regenerated solution. This regenerated solution allows the deactivated denitration catalyst to regain activity while simultaneously possessing the ability to jointly oxidize and remove mercury. However, the denitration catalyst regenerated using this solution has limited loading capacity of active components, requiring repeated impregnation to achieve the desired effect. Active components tend to aggregate in the same area, and blockage of active sites can directly lead to catalyst deactivation.

[0007] In summary, existing denitrification catalyst regeneration methods still mainly rely on the traditional process of dust removal, chemical cleaning, and active loading, resulting in a narrow range of applications for the regenerated denitrification catalyst. While methods that improve the combined denitrification and mercury removal performance by introducing components such as cerium suffer from low economic efficiency, poor combined denitrification and mercury removal performance, and low dispersion of active components. Summary of the Invention

[0008] The purpose of this invention is to address the limitations of existing denitrification catalyst regeneration methods. Traditional processes involving ash removal, chemical cleaning, and active loading result in a narrow application range of the regenerated denitrification catalyst. Furthermore, methods that improve the combined denitrification and mercury removal performance by introducing components such as cerium suffer from low economic efficiency, poor combined denitrification and mercury removal performance, and low dispersion of active components.

[0009] A method for modifying and regenerating a deactivated denitrification catalyst is characterized by the following steps: First, the deactivated catalyst is broken down into uniform block-shaped units, and the surface dust is removed by high-pressure gas purging; second, ultrasonic chemical cleaning is performed, and the cleaned catalyst is first immersed in regeneration solution A at a controlled temperature. After immersion, it is dried and subjected to sulfidation treatment; after sulfidation treatment, the catalyst is immersed in regeneration solution B at a controlled temperature; finally, the catalyst is calcined to complete the modification and regeneration of the catalyst.

[0010] Furthermore, the block catalyst is cuboid in shape, with a length of 20-100 mm, a width of 20-100 mm, and a height of 40-200 mm.

[0011] Furthermore, the high-pressure gas pressure is 0.2–0.6 MPa, and the purging time is 0.4–2.0 h.

[0012] Furthermore, the ultrasonic chemical cleaning process involves sequentially ultrasonically cleaning the catalyst with an ammonia solution of concentration 3-5 mol / L, a sulfuric acid solution of concentration 0.5-2.0 mol / L, and deionized water for 5-15 minutes at an ultrasonic frequency of 25-30 kHz. During the ultrasonic cleaning process, the catalyst is flipped over at 2.5-7.5 minutes.

[0013] Furthermore, in the process of temperature-controlled immersion in regeneration solution A, the immersion temperature is 70-90℃, the immersion time is 2-3h, and the regeneration solution A is a citric acid solution that dissolves cerium nitrate hexahydrate, with the amount of cerium nitrate hexahydrate added being 0.5-1.0mol / L; the concentration of the citric acid solution is 1.5-3.0mol / L.

[0014] Furthermore, the drying process is carried out in a nitrogen atmosphere, at a drying temperature of 190–250°C, and for a drying time of 0.2–0.5 h. The sulfidation process involves placing the catalyst in a flow reactor, continuously heating it, and introducing a flowing gas. The flowing gas consists of nitrogen containing 300–500 ppm sulfur dioxide and 5–10% vol oxygen. The heating temperature is 250–350°C, and the heating time is 1–2 h.

[0015] Furthermore, in the process of temperature-controlled immersion in regeneration solution B, the immersion temperature is 70-90℃ and the immersion time is 1-3h. The regeneration solution B is an ethanolamine solution that dissolves ammonium metavanadate, and the amount of ammonium metavanadate added is 0.5-1.0 mol / L; the concentration of the ethanolamine solution is 0.5-2.0 mol / L.

[0016] Furthermore, the furnace temperature used in the roasting process is 350-450℃, the roasting time is 2-4h, and the heating rate is 3-7℃ / min; while removing excess loading liquid, the active components of cerium and vanadium are fully adhered.

[0017] like Figure 1 The method for modifying and regenerating a deactivated denitration catalyst, as shown, specifically includes the following steps:

[0018] Step 1: The deactivated catalyst is broken down into rectangular block-shaped integral catalysts with a length of 20-100 mm, a width of 20-100 mm, and a height of 40-200 mm;

[0019] Step 2: Purge the surface dust with high-pressure gas at 0.2-0.6 MPa for 0.4-2.0 hours;

[0020] Step 3: The ash-removed block catalyst is sequentially immersed in an ammonia solution with a concentration of 3-5 mol / L, a sulfuric acid solution with a concentration of 0.5-2.0 mol / L, and deionized water for ultrasonic cleaning for 5-15 minutes at an ultrasonic frequency of 25-30 kHz. During the ultrasonic cleaning process, the catalyst is turned upside down at 2.5-7.5 minutes to fully clean and remove the poisoning factors that cause the deactivation of the catalyst.

[0021] Step 4: Prepare a 1.5–3.0 mol / L citric acid solution, add 0.5–1.0 mol / L cerium nitrate hexahydrate, and wait until the citric acid solution loaded with cerium nitrate hexahydrate is completely in gel form to complete the preparation of regeneration solution A. Weigh the catalyst according to its volume to prepare regeneration solution A, immerse the cleaned catalyst in regeneration solution A, control the temperature at 70–90℃, and immerse for 2–3 hours to complete the loading process of regeneration solution A.

[0022] Step 5: After completing the impregnation process of regenerated liquid A, place the catalyst in a drying oven and dry it at 190-250℃ for 0.2-0.5 hours under a nitrogen atmosphere until the citric acid colloid on the catalyst surface is completely evaporated, thus completing the drying process.

[0023] Step 6: Sulfide treatment of the catalyst. The catalyst is placed in a flow reactor and heated to 250-350°C while a flowing gas is continuously introduced. The flowing gas consists of nitrogen containing 300-500 ppm sulfur dioxide and 5-10% vol oxygen for 1-2 hours.

[0024] Step 7: Prepare a 0.5–2.0 mol / L ethanolamine solution, add 0.5–1.0 mol / L ammonium metavanadate and stir until the solution is clear to complete the preparation of regeneration solution B. Weigh the catalyst according to its volume to prepare regeneration solution B, immerse the cleaned catalyst in regeneration solution B, control the temperature at 70–90℃, and immerse for 1–3 hours.

[0025] Step 8: After impregnation with regenerated solution B, place the catalyst in a calcination furnace and calcine it at 350–450°C for 2–4 hours at a heating rate of 3–7°C / min. This removes excess loading solution and ensures sufficient adhesion of the cerium and vanadium active components.

[0026] The technical principle of this invention is as follows:

[0027] 1. During catalyst regeneration, when V and Ce are simultaneously loaded onto the deactivated catalyst, the V and Ce on the catalyst surface will eventually transform into two redox pairs: V₂O₅ / VO₄ and CeO₂ / Ce₂O₃. 4+ The denitrification process is shown in equations (1) to (3). If the catalyst surface Ce 4+ Excessive amounts of NH2 can easily promote further oxidation to N2O. To avoid this, reaction (4) is promoted through sulfidation. 4+ It will transform into Ce 3+ This promotes Ce on the catalyst surface 3+ enrichment of SO4 2- The introduction of [agents] can also lead to the enrichment of strongly acidic sites on the catalyst surface, increasing the surface acidity. The presence of the V₂O₅ / VO₄ redox pair promotes Ce [reactivity] on the catalyst surface.4+ Transformed into Ce 3+ Ce 3+ It provides more active oxygen sites, resulting in a higher concentration of surface-adsorbed oxygen on the catalyst surface.

[0028] NH3+Ce 4+ →-NH2+Ce 3+ +H + (1)

[0029] -NH2+NO(g)→N2+H2O (2)

[0030] 4Ce 3+ +O2→4Ce 4+ +2O 2- (3)

[0031] 2CeO2 + 3SO2 + O2 = Ce2(SO4)3 (4)

[0032] Hg in flue gas 0 Due to its high volatility and poor water solubility, Ce is difficult to remove. After the addition of V and Ce and subsequent sulfidation, a high concentration of Ce accumulates on the catalyst surface. 3+ The abundant surface-adsorbed oxygen provided can significantly enhance the oxidation performance of the catalyst surface, promoting the reduction of Hg in the flue gas. 0 Oxidized to Hg 2+ Using Hg 2+ The water solubility of Ce leads to its removal in subsequent equipment. Surface-enriched Ce... 3+ It can also generate more B acidic sites, improving the denitrification performance of the catalyst.

[0033] 2. The cerium component is added to the citric acid solvent to form a low-viscosity solution. After the cerium component and the citric acid solvent are uniformly mixed, hydrolysis and condensation chemical reactions occur, forming a stable transparent sol system in the solution. The sol gradually forms a gel after precipitation. During the transformation from sol to gel, the cerium component is highly uniformly dispersed in the sol. During the drying process, the citric acid volatilizes, forming carbon deposits with a high specific surface area, while the cerium-containing gel component is dried, sintered, and solidified, ultimately transforming into highly dispersed micro-cerium oxide / cerium nitride particles on the catalyst surface.

[0034] This invention, based on traditional catalyst regeneration methods, utilizes a sol-gel method to highly disperse cerium components on the surface of the denitrification catalyst. Simultaneously, the surface carbon generated after drying the citric acid-supported solution provides numerous active sites for the catalyst. The sulfidation reaction promotes the formation of cerium redox pairs, which interact with vanadium redox pairs, exhibiting excellent combined denitrification and mercury removal performance. After regeneration, it can be deployed in areas of thermal power plants, chemical plants, and other facilities where flue gas contains both nitrogen oxides and mercury vapor, broadening the application range of regenerated denitrification catalysts. The regeneration process is simple, economically efficient, and has wide application value.

[0035] The beneficial technical effects of the present invention are as follows:

[0036] 1. In the process of regenerating vanadium-titanium denitration catalysts, cerium is supported as a modifying element while restoring the active component vanadium. This allows the regenerated catalyst to simultaneously possess the ability to denitrate and oxidize zero-valent mercury, broadening the application range of the regenerated denitration catalyst. The redox pairs formed by the two supported components after calcination can interconvert, creating a large number of oxygen vacancies, effectively increasing the operating temperature range of the denitration catalyst.

[0037] 2. Deactivated catalysts can be fully recovered and utilized, including a small amount of active components on the catalyst surface and a support with a high specific surface area, which can reduce the cost of catalyst regeneration. The raw materials for the regeneration process are readily available, resulting in high economic benefits.

[0038] 3. Vanadium and cerium active components are uniformly dispersed on the surface of the support, which has many active sites. The combined denitrification and mercury removal effects are good, and the regenerated catalyst after sulfidation treatment has strong sulfur resistance. Attached Figure Description

[0039] Figure 1 This is a flowchart of the modification and regeneration process of a deactivated denitrification catalyst according to the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art will fully understand the invention even without these detailed descriptions. This invention covers any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of the invention as defined in the claims.

[0041] Example 1

[0042] The deactivated catalyst was disassembled into rectangular blocks measuring 100 mm in length, 100 mm in width, and 200 mm in height. Surface dust was removed by purging with high-pressure gas at 0.6 MPa for 2.0 h. The cleaned catalyst blocks were then sequentially immersed in a 5.0 mol / L ammonia solution, a 2.0 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 30 kHz for 15 min. During the ultrasonic cleaning process, the catalyst was inverted at 7.5 min. A 3.0 mol / L citric acid solution was prepared, and 1.0 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 90℃ for 3 h. After impregnation, the catalyst was dried in a drying oven at 250°C for 0.5 h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 350°C while continuously purging with nitrogen gas containing 500 ppm sulfur dioxide and 10% vol oxygen for 2.0 h. After the sulfidation process, a 2.0 mol / L ethanolamine solution was prepared, and 1.0 mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume, and the temperature was controlled at 90°C. The cleaned catalyst was impregnated in regeneration solution B for 3.0 h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 450°C for 4 h at a heating rate of 7°C / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 88.2% at temperatures ranging from 200°C to 450°C.

[0043] Example 2

[0044] The deactivated catalyst was disassembled into rectangular blocks measuring 80 mm in length, 80 mm in width, and 160 mm in height. Surface dust was removed by purging with high-pressure gas at 0.5 MPa for 1.6 h. The cleaned catalyst blocks were then sequentially immersed in a 4.5 mol / L ammonia solution, a 1.6 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 29 kHz for 12 min. During the ultrasonic cleaning process, the catalyst was inverted at 6.0 min. A 2.7 mol / L citric acid solution was prepared, and 0.9 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 83℃ for 2.8 h. After impregnation, the catalyst was dried in a drying oven at 240℃ for 0.3h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 320℃ while continuously purging with nitrogen gas containing 460ppm sulfur dioxide and 9.0% vol oxygen for 1.8h. After the sulfidation process, a 1.6mol / L ethanolamine solution was prepared, and 0.9mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 83℃. The cleaned catalyst was impregnated in regeneration solution B for 2.6h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 430℃ for 3.5h at a heating rate of 6℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 86.4% at 200℃–450℃.

[0045] Example 3

[0046] The deactivated catalyst was disassembled into rectangular blocks measuring 60 mm in length, 60 mm in width, and 120 mm in height. Surface dust was removed by purging with high-pressure gas at 0.4 MPa for 1.2 h. The cleaned catalyst blocks were then sequentially immersed in a 4.0 mol / L ammonia solution, a 1.2 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 28 kHz for 14 min. During the ultrasonic cleaning process, the catalyst was inverted at 7.0 min. A 2.3 mol / L citric acid solution was prepared, and 0.8 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 76℃ for 2.6 h. After impregnation, the catalyst was dried in a drying oven at 230℃ for 0.4 h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 300℃ while continuously purging with nitrogen gas containing 440 ppm sulfur dioxide and oxygen at 8.5% vol for 1.6 h. After the sulfidation process, a 1.2 mol / L ethanolamine solution was prepared, and 0.8 mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 76℃. The cleaned catalyst was impregnated in regeneration solution B for 2.2 h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 430℃ for 3.0 h at a heating rate of 5℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 83.7% at 200℃–450℃.

[0047] Example 4

[0048] The deactivated catalyst was disassembled into rectangular blocks measuring 40 mm in length, 40 mm in width, and 80 mm in height. Surface dust was removed by purging with high-pressure gas at 0.3 MPa for 0.8 h. The cleaned catalyst blocks were then sequentially immersed in a 3.5 mol / L ammonia solution, a 0.8 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 27 kHz for 10 min. During ultrasonic cleaning, the catalyst was inverted at 5.0 min. A 1.9 mol / L citric acid solution was prepared, and 0.7 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was allowed to gel completely, thus preparing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 82℃ for 2.4 h. After impregnation, the catalyst was dried in a drying oven at 220℃ for 0.2 h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 280℃ while continuously purging with nitrogen gas containing 400 ppm sulfur dioxide and 7.5% vol oxygen for 1.2 h. After the sulfidation process, a 0.8 mol / L ethanolamine solution was prepared, and 0.7 mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 82℃. The cleaned catalyst was impregnated in regeneration solution B for 7.8 h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 390℃ for 2.5 h at a heating rate of 4℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 84.3% at 200℃–450℃.

[0049] Example 5

[0050] The deactivated catalyst was disassembled into rectangular blocks measuring 20 mm in length, 20 mm in width, and 40 mm in height. Surface dust was removed by purging with high-pressure gas at 0.2 MPa for 0.4 h. The cleaned catalyst blocks were then sequentially immersed in a 3.0 mol / L ammonia solution, a 0.5 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 26 kHz for 8 min. During ultrasonic cleaning, the catalyst was inverted at 4.0 min. A 1.5 mol / L citric acid solution was prepared, and 0.6 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. Regeneration solution A was prepared by weighing the catalyst according to its volume. The cleaned catalyst was then immersed in regeneration solution A at 88℃ for 2.2 h. After impregnation, the catalyst was dried in a drying oven at 210℃ for 0.2h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 260℃ while continuously purging with nitrogen gas containing 350ppm sulfur dioxide and 6.5% vol oxygen for 1.0h. After the sulfidation process, a 0.6mol / L ethanolamine solution was prepared, and 0.5mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume, and the temperature was controlled at 88℃. The cleaned catalyst was impregnated in regeneration solution B for 1.4h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 370℃ for 2.0h at a heating rate of 3℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 81.8% at temperatures ranging from 200℃ to 450℃.

[0051] Example 6

[0052] The deactivated catalyst was disassembled into rectangular blocks measuring 100 mm in length, 100 mm in width, and 200 mm in height. Surface dust was removed by purging with high-pressure gas at 0.6 MPa for 2.0 h. The cleaned catalyst blocks were then sequentially immersed in a 5.0 mol / L ammonia solution, a 2.0 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 30 kHz for 14 min. During the ultrasonic cleaning process, the catalyst was inverted at 7.0 min. A 1.5 mol / L citric acid solution was prepared, and 0.5 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was allowed to gel completely, thus preparing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 72℃ for 3.0 h. After impregnation, the catalyst was dried in a drying oven at 230℃ for 0.3h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 350℃ while continuously purging with nitrogen gas containing 460ppm sulfur dioxide and 9.0% vol oxygen for 1.8h. After the sulfidation process, a 0.5mol / L ethanolamine solution was prepared, and 0.5mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 72℃. The cleaned catalyst was impregnated in regeneration solution B for 2.6h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 430℃ for 4.0h at a heating rate of 7℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 80.4% at temperatures ranging from 200℃ to 450℃.

[0053] Example 7

[0054] The deactivated catalyst was disassembled into rectangular blocks measuring 80 mm in length, 80 mm in width, and 160 mm in height. Surface dust was removed by purging with high-pressure gas at 0.5 MPa for 1.6 h. The cleaned catalyst blocks were then sequentially immersed in a 4.5 mol / L ammonia solution, a 1.6 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 29 kHz for 6 min. During ultrasonic cleaning, the catalyst was inverted at 3.0 min. A 1.9 mol / L citric acid solution was prepared, and 0.6 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 76℃ for 2.8 h. After impregnation, the catalyst was dried in a drying oven at 220°C for 0.3 h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 320°C while continuously purging with nitrogen gas containing 380 ppm sulfur dioxide and 7.0% vol oxygen for 1.6 h. After the sulfidation process, a 0.9 mol / L ethanolamine solution was prepared, and 0.6 mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 76°C. The cleaned catalyst was impregnated in regeneration solution B for 2.2 h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 390°C for 3.5 h at a heating rate of 6°C / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 82.9% at 200°C–450°C.

[0055] Example 8

[0056] The deactivated catalyst was disassembled into rectangular blocks measuring 60 mm in length, 60 mm in width, and 120 mm in height. Surface dust was removed by purging with high-pressure gas at 0.4 MPa for 1.2 h. The cleaned catalyst blocks were then sequentially immersed in a 4.0 mol / L ammonia solution, a 1.2 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 28 kHz for 12 min. During the ultrasonic cleaning process, the catalyst was inverted at 6.0 min. A 2.3 mol / L citric acid solution was prepared, and 0.7 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 86℃ for 2.6 h. After impregnation, the catalyst was dried in a drying oven at 210℃ for 0.2h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 300℃ while continuously purging with nitrogen gas containing 400ppm sulfur dioxide and 7.5% vol oxygen for 1.4h. After the sulfidation process, a 1.3mol / L ethanolamine solution was prepared, and 0.7mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 86℃. The cleaned catalyst was impregnated in regeneration solution B for 1.8h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 390℃ for 3.0h at a heating rate of 5℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 83.1% at 200℃–450℃.

[0057] Example 9

[0058] The deactivated catalyst was disassembled into rectangular blocks measuring 40 mm in length, 40 mm in width, and 80 mm in height. Surface dust was removed by purging with high-pressure gas at 0.3 MPa for 0.8 h. The cleaned catalyst blocks were then sequentially immersed in a 3.5 mol / L ammonia solution, a 0.8 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 27 kHz for 10 min. During the ultrasonic cleaning process, the catalyst was inverted after 5 min. A 2.7 mol / L citric acid solution was prepared, and 0.8 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was prepared until it completely formed a gel, thus completing regeneration solution A. The catalyst volume was weighed according to the regeneration solution A. The cleaned catalyst was then immersed in regeneration solution A at 77℃ for 2.4 h. After impregnation, the catalyst was dried in a drying oven at 200℃ for 0.4h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 280℃ while continuously purging with nitrogen gas containing 480ppm sulfur dioxide and 9.5% vol oxygen for 1.2h. After the sulfidation process, a 1.7mol / L ethanolamine solution was prepared, and 0.8mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume and controlling the temperature at 77℃. The cleaned catalyst was impregnated in regeneration solution B for 1.4h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 370℃ for 2.5h at a heating rate of 4℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 82.6% at 200℃–450℃.

[0059] Example 10

[0060] The deactivated catalyst was disassembled into rectangular blocks, each 20 mm long, 20 mm wide, and 40 mm high. Surface dust was removed by purging with high-pressure gas at 0.2 MPa for 0.4 h. The cleaned catalyst blocks were then sequentially immersed in a 3.0 mol / L ammonia solution, a 0.5 mol / L sulfuric acid solution, and deionized water, and ultrasonically cleaned at 25 kHz for 5 min. During ultrasonic cleaning, the catalyst was inverted after 2.5 min. A 3.0 mol / L citric acid solution was prepared, and 0.9 mol / L cerium nitrate hexahydrate was added. The citric acid solution containing cerium nitrate hexahydrate was allowed to gel completely, thus preparing regeneration solution A. Regeneration solution A was prepared by weighing the catalyst according to its volume. The cleaned catalyst was then immersed in regeneration solution A at 70℃ for 2.0 h. After impregnation, the catalyst was dried in a drying oven at 190℃ for 0.5 h under a nitrogen atmosphere. Then, the catalyst was placed in a flow reactor and heated to 260℃ while continuously purging with nitrogen gas containing 320 ppm sulfur dioxide and 5.5% vol oxygen for 1.0 h. After the sulfidation process, a 1.0 mol / L ethanolamine solution was prepared, and 0.9 mol / L ammonium metavanadate was added and stirred until the solution was clear, thus preparing regeneration solution B. Regeneration solution B was prepared by weighing the catalyst according to its volume, and the temperature was controlled at 70℃. The cleaned catalyst was impregnated in regeneration solution B for 1.0 h. After impregnation with regeneration solution B, the catalyst was placed in a calcination furnace and calcined at 350℃ for 2.0 h at a heating rate of 3℃ / min. The regenerated denitrification catalyst exhibited a denitrification and mercury removal performance of 84.1% at 200℃–450℃.

Claims

1. A method for modifying and regenerating a deactivated denitration catalyst, characterized in that, First, the deactivated catalyst is broken down into uniform block-shaped pieces and its surface dust is removed by purging with high-pressure gas at 0.2–0.6 MPa. Next, it undergoes ultrasonic chemical cleaning. The cleaned catalyst is then immersed in regeneration solution A at a controlled temperature. After immersion, it is dried and subjected to sulfidation treatment. The sulfidation process involves placing the catalyst in a flow reactor, continuously heating it, and introducing a flowing gas. The flowing gas consists of nitrogen containing 300–500 ppm sulfur dioxide and 5–10% vol oxygen. The heating temperature is 250–350°C, and the heating time is 1–2 hours. After sulfidation, the catalyst is immersed in regeneration solution B at a controlled temperature. Finally, the catalyst is calcined to complete the modification and regeneration of the catalyst. The process of temperature-controlled immersion in regeneration solution A involves an immersion temperature of 70–90°C and an immersion time of 2–3 hours. Regeneration solution A is a citric acid solution that dissolves cerium nitrate hexahydrate, with the amount of cerium nitrate hexahydrate added being 0.5–1.0 mol / L and the concentration of the citric acid solution being 1.5–3.0 mol / L. The process of temperature-controlled immersion in regeneration solution B involves an immersion temperature of 70–90°C and an immersion time of 1–3 hours. The regeneration solution B is an ethanolamine solution in which ammonium metavanadate is dissolved, with the amount of ammonium metavanadate added being 0.5–1.0 mol / L and the concentration of the ethanolamine solution being 0.5–2.0 mol / L.

2. The method for modifying and regenerating a deactivated denitrification catalyst according to claim 1, characterized in that, The block catalyst is rectangular in shape, with a length of 20-100 mm, a width of 20-100 mm, and a height of 40-200 mm.

3. The method for modifying and regenerating a deactivated denitrification catalyst according to claim 1, characterized in that, The high-pressure gas purging time is 0.4 to 2.0 hours.

4. The method for modifying and regenerating a deactivated denitrification catalyst according to claim 1, characterized in that, The ultrasonic chemical cleaning process involves sequentially ultrasonically cleaning the catalyst with ammonia solution of concentration 3-5 mol / L, sulfuric acid solution of concentration 0.5-2.0 mol / L, and deionized water for 5-15 minutes at an ultrasonic frequency of 25-30 kHz. During the ultrasonic cleaning process, the catalyst is flipped over at 2.5-7.5 minutes.

5. The method for modifying and regenerating a deactivated denitrification catalyst according to claim 1, characterized in that, The drying process is carried out in a nitrogen atmosphere, at a temperature of 190–250°C, and for a time of 0.2–0.5 h.

6. The method for modifying and regenerating a deactivated denitration catalyst according to claim 1, characterized in that, The furnace temperature used in the roasting process is 350-450℃, the roasting time is 2-4h, and the heating rate is 3-7℃ / min. This process removes excess load liquid while ensuring the full adhesion of cerium and vanadium active components.

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