Regeneration process of inactivated low-temperature denitration catalyst

Abstract

The invention relates to a regeneration process of an inactivated low-temperature denitration catalyst, and belongs to the technical field of catalyst regeneration. The process comprises the following steps: recovering and grinding a deactivated catalyst until the particle size is less than or equal to 425 microns, performing low-temperature plasma reaction activation, mixing and stirring with a mixed solution of a specific component emulsifier and dilute sulphuric acid according to a certain liquid-solid ratio, performing ultrasonic reaction, and filtering to obtain pretreated catalyst particles; mixing the pretreated particles with a potassium molybdate solution in proportion, and dipping in three stages; then, the impregnated particles are dried, calcined and passivated; mixing the passivated particles with glycerol and glass fibers according to a mass ratio, and pressing into a honeycomb-shaped blank body; and finally, drying the blank by adopting an infrared-hot air coupling drying technology, and calcining to obtain the final regenerated catalyst. Meanwhile, the method is also suitable for medium-temperature and medium-high temperature denitration catalysts and integral regeneration of the catalysts.

Description

Technical Field

[0001] This invention belongs to the field of catalyst regeneration technology and relates to a process for regenerating deactivated low-temperature denitrification catalysts. Background Technology

[0002] Low-temperature denitrification technology plays a crucial role in controlling nitrogen oxide (NOx) emissions. As the core component of this technology, low-temperature denitrification catalysts can efficiently convert NOx into harmless nitrogen and water at relatively low temperatures, and are widely used in flue gas purification in industries such as power generation, steel, chemicals, cement, hazardous waste disposal, biomass incineration, and waste incineration.

[0003] However, in actual operation, low-temperature denitrification catalysts gradually deactivate due to various factors. For example, dust particles in the flue gas deposit and clog the catalyst pores, obstructing gas flow; heavy metals and alkali metals adsorb or react on the catalyst surface, altering its chemical composition and structure; and high-temperature sintering and water vapor poisoning all significantly reduce the catalyst's activity and lifespan. Directly discarding deactivated catalysts not only wastes resources and increases operating costs but also causes secondary pollution. Therefore, regenerating deactivated low-temperature denitrification catalysts to restore their catalytic activity and achieve resource recycling is of significant economic and environmental importance.

[0004] Currently, existing catalyst regeneration processes have many limitations, such as unsatisfactory regeneration effects, difficulty in fully restoring the catalyst's initial activity, complex regeneration processes, harsh operating conditions, and high equipment requirements; and the potential introduction of new impurities or damage to the catalyst structure during regeneration. Therefore, there is an urgent need to develop a highly efficient, simple, and environmentally friendly low-temperature denitrification catalyst regeneration process. This newly developed low-temperature denitrification catalyst regeneration process can also be applied to medium-temperature, medium-high temperature denitrification catalysts, and the overall regeneration of catalysts. Summary of the Invention

[0005] The purpose of this invention is to provide a regeneration process for deactivated low-temperature denitrification catalysts, which features high mechanical strength of the regenerated catalyst.

[0006] The objective of this invention can be achieved through the following technical solutions: A regeneration process for a deactivated low-temperature denitration catalyst, the regeneration process comprising the following steps: S1: The deactivated low-temperature denitrification catalyst is recovered and ground in a ball mill at 400 r / min for 8-12 h until the catalyst particle size is ≤425 μm. The ground catalyst particles are subjected to low-temperature plasma reaction for 2.5-3 h in an atmosphere of SO2 / H2S / air mixture. The activated catalyst particles are mixed with emulsifier and dilute sulfuric acid solution at a liquid-solid ratio of 4:1 and stirred for 0.5-1 h. Then, the mixture is ultrasonically reacted for 10-15 min and filtered to obtain the pretreated catalyst particles. The emulsifier components are, by mass percentage: 30% polyethylene glycol 2000, 10% sodium dodecylbenzenesulfonate, 10% citric acid, 10% disodium ethylenediaminetetraacetate, 20% nano silica dispersion, 5% isopropanol, and 25% deionized water. S2: The pretreated catalyst particles were mixed with a 0.25 mol / L potassium molybdate solution at a liquid-solid ratio of 3:1 and impregnated in three stages: the first stage was impregnation at room temperature for 30 min; the second stage was impregnation at 60°C after heating at 2°C / min for 60 min; the third stage was impregnation at 80°C after adding vanadium oxalate solution and heating at 1°C / min for 90 min. S3: After the impregnation is completed, the catalyst particles are dried at 110℃ for 12-16 hours and then transferred to a muffle furnace for processing according to the following procedure: First stage: the temperature is increased from room temperature to 200℃ at 5℃ / min and calcined for 1-2 hours; Second stage: the temperature is increased to 450℃ at 3℃ / min and calcined for 3 hours; Third stage: after natural cooling to 150℃, NH3 / N2 mixed gas is introduced for passivation treatment, and the passivation treatment time is 3-4 hours. S4: The passivated catalyst particles are mixed with glycerol and glass fiber in a mass ratio of 4:1:1 and pressed into a honeycomb catalyst preform by a vacuum extruder. The catalyst preform has a pore density of 400 cpsi and a wall thickness of 0.8 mm. S5: The prepared catalyst preform was dried using infrared-hot air coupled drying technology. After drying, it was transferred to a muffle furnace and heated to 500℃ at 2℃ / min for 4 hours to obtain the regenerated catalyst.

[0007] Furthermore, the low-temperature plasma reaction parameters in S1 are: voltage 75kV, and mixed gas volume ratio of SO2 / H2S / air = (20~30%):(10~15%):(55~70%).

[0008] Furthermore, the concentration of dilute sulfuric acid in S1 is 0.1~0.3 mol / L.

[0009] Furthermore, in the S1 mixture of emulsifier and dilute sulfuric acid, the volume ratio of emulsifier to dilute sulfuric acid is 1:(1~2).

[0010] Furthermore, the solid content of the nano-silica dispersion in the emulsifier in S1 is 20%.

[0011] Furthermore, the concentration range of the vanadium oxalate solution in the third stage of S2 is 0.08~0.15 mol / L.

[0012] Furthermore, the volume ratio of the NH3 / N2 mixed gas in S3 is 1:9.

[0013] Furthermore, the mass fraction of glycerol in S4 is 2-5%.

[0014] Furthermore, the length of the glass fiber in S5 ranges from 1 to 5 mm.

[0015] Furthermore, in S5, the infrared radiation drying temperature range is 50~70℃, and the hot air drying temperature range is 90~110℃.

[0016] This regeneration process endows the regenerated catalyst with excellent mechanical strength. In step S4, passivated catalyst particles are mixed with glycerol and glass fiber at a mass ratio of 4:1:1, and then pressed into a honeycomb catalyst preform using a vacuum extruder. Glass fiber possesses high strength and high modulus; during mixing, it is uniformly dispersed among the catalyst particles, forming a structure that reinforces the catalyst framework. When the catalyst is subjected to external forces, the glass fiber can bear and disperse some of the stress, effectively preventing the propagation and expansion of cracks. In practical applications, the catalyst may be subjected to external forces such as airflow impacts and particle collisions. The reinforcing effect of the glass fiber allows the catalyst preform to maintain its structural integrity under these forces, making it less prone to breakage or damage, thereby significantly improving the overall mechanical strength of the catalyst preform.

[0017] Glycerin also plays a crucial role in enhancing mechanical strength. With its viscosity and lubricity, glycerin facilitates better bonding between catalyst particles and glass fibers during mixing, strengthening their adhesion. This enhanced adhesion helps form a compact and stable structure, further constructing a robust framework for the catalyst preform. During subsequent drying and calcination, this structure is consolidated and strengthened, resulting in a regenerated catalyst with high mechanical strength. This makes it better suited to the complex and harsh environments of actual industrial applications, reducing catalyst damage and failure caused by mechanical forces and significantly extending catalyst lifespan.

[0018] This process can efficiently restore the activity of deactivated low-temperature denitration catalysts. In step S1, the deactivated catalyst is first recovered and ground in a ball mill to a particle size ≤425μm. The grinding process not only reduces the catalyst particle size and increases its specific surface area, providing more active sites for the reaction, but also destroys any carbon deposits or capping layers that may exist on the catalyst surface, exposing more previously obscured active centers. Carbon deposits may cover the active sites on the catalyst surface, hindering the contact between reactants and active centers. After grinding, the carbon deposits are removed, and the active centers are re-exposed, laying the foundation for subsequent activity recovery.

[0019] Next, the present invention subjectes the ground catalyst particles to a low-temperature plasma reaction in a SO2 / H2S / air mixed gas atmosphere. The low-temperature plasma contains a large number of high-energy particles, free radicals, and active species. High-energy electrons can excite SO2 and H2S molecules, causing them to generate highly oxidizing free radicals, hydroxyl radicals, and sulfur oxide radicals. These free radicals can oxidize and decompose organic contaminants and sulfides on the catalyst surface, converting them into easily removable carbon dioxide, water, and sulfates. Subsequently, the activated catalyst particles are mixed with an emulsifier and a dilute sulfuric acid solution at a certain liquid-solid ratio, stirred, and subjected to ultrasonic reaction. Components in the emulsifier can further remove stubborn stains and heavy metal ions from the catalyst surface. Citric acid and disodium EDTA, as chelating agents, can form stable chelates with heavy metal ions (such as mercury, lead, cadmium, etc.) on the catalyst surface. These chelates have high stability and can be removed from the catalyst surface through filtration and other operations, preventing heavy metal ions from inhibiting catalyst activity. Dilute sulfuric acid can dissolve some alkaline oxides or react with some substances on the catalyst surface, further cleaning and activating the catalyst surface. The cavitation effect generated by ultrasonic reaction can produce strong microjets and shock waves, which accelerate the exchange of substances between the mixed solution and the catalyst surface, improve the cleaning and activation effect, and allow the active centers on the catalyst surface to be more fully exposed and restored.

[0020] In step S2, the pretreated catalyst particles are impregnated in stages with potassium molybdate solution and vanadium oxalate solution. Molybdenum and vanadium are common active components in low-temperature denitrification catalysts. In the room-temperature impregnation stage, molybdenum ions in the potassium molybdate solution are gradually adsorbed onto the catalyst surface, providing a basis for subsequent loading of active components. As the temperature rises to 60°C and is maintained for a certain period, molybdenum ions react chemically with hydroxyl and carboxyl groups on the catalyst surface, forming more stable chemical bonds, further enhancing the fixation of molybdenum on the catalyst surface. In the third stage, vanadium oxalate solution is added and the temperature is raised to 80°C for impregnation, and vanadium ions are similarly loaded onto the catalyst surface through adsorption and chemical reaction. The synergistic effect of molybdenum and vanadium can optimize the electronic structure and active site distribution on the catalyst surface, improving the catalyst's adsorption and catalytic conversion capacity for NOx. The specific ratio and distribution of molybdenum and vanadium can further regulate the acidity and redox properties of the catalyst surface, enabling the catalyst to more effectively convert NOx into nitrogen and water under low-temperature conditions, thereby effectively restoring the catalyst's denitrification activity.

[0021] This process helps enhance the structural stability of the catalyst. In step S3, the impregnated catalyst particles are dried and calcined. The drying process removes moisture from the catalyst particles, preventing damage to the catalyst structure during subsequent high-temperature treatment. The calcination process is divided into several stages. The first stage involves heating from room temperature to 200°C at a rate of 5°C / min and calcining for 1-2 hours. This stage primarily aims to further decompose and volatilize the organic matter and volatile substances inside the catalyst particles, initially stabilizing the catalyst structure. The second stage involves heating to 450°C at a rate of 3°C / min and calcining for 3 hours. At this temperature, the active components on the catalyst surface interact more strongly with the support, forming more stable chemical bonds and crystal structures. For example, the chemical bonds between the active components molybdenum and vanadium and the support are stronger, allowing the active components to be better fixed on the support and reducing loss during subsequent use. After naturally cooling to 150°C in the third stage, a mixture of NH3 / N2 gas is introduced for passivation treatment. Passivation treatment can form a thin and stable oxide film on the catalyst surface. This oxide film can prevent the catalyst from reacting excessively with the reactant gas during actual use, protect the internal structure of the catalyst from damage, and further improve the structural stability and service life of the catalyst.

[0022] Through this regeneration process, the pore structure of the catalyst is optimized. During the grinding process in step S1, while appropriately reducing the catalyst particle size, the internal pore structure of the particles is also improved to some extent, making the pores more open. The high-energy particles and active species generated during the low-temperature plasma reaction can clean and modify the pores on the catalyst surface, removing blockages, expanding the pore size, and increasing the pore volume. Any carbon deposits or small particulate impurities that may exist within the pores are bombarded and oxidized by the high-energy particles, clearing the pores and providing better pathways for the diffusion of reactants and products.

[0023] During the impregnation process in step S2, potassium molybdate solution and vanadium oxalate solution enter the pores of the catalyst. As the temperature increases and the chemical reaction proceeds, the active components are uniformly distributed within the pores, forming a specific structure. This distribution and structure help adjust the pore structure of the catalyst, resulting in a more suitable pore size distribution and specific surface area. A suitable pore size distribution can improve the diffusion efficiency of reactant molecules within the catalyst pores, making it easier for reactants to reach the active sites for reaction. It also facilitates the timely removal of product molecules, reducing diffusion resistance and improving the efficiency of the catalytic reaction. For example, smaller pore sizes increase the contact opportunities between reactants and active sites, while larger pore sizes facilitate the rapid removal of products, preventing product accumulation within the pores and thus catalyst deactivation.

[0024] The regeneration process of this invention has strong adaptability and can be applied to various types of deactivated low-temperature denitrification catalysts. Whether the catalyst is deactivated due to carbon buildup, sulfide poisoning, or heavy metal contamination, this process can effectively regenerate it through appropriate steps. For deactivation caused by carbon buildup, grinding and low-temperature plasma reaction can effectively remove the carbon deposits; for sulfide poisoning, low-temperature plasma reaction and dilute sulfuric acid treatment can oxidize and dissolve the sulfides; for heavy metal contamination, the chelating agent in the emulsifier can remove heavy metal ions. Moreover, the process parameters can be appropriately adjusted according to the specific deactivation conditions and performance requirements of different catalysts, such as the parameters of the low-temperature plasma reaction, the concentration and impregnation time of the impregnation solution, and the calcination temperature and time, to achieve the best regeneration effect, thus having broad application prospects.

[0025] Furthermore, from an environmental perspective, this regeneration process reduces the pollution caused by the disposal and treatment of deactivated catalysts. Regeneration through this process allows these catalysts to be reused, reducing environmental pressure. From an economic perspective, the cost of the regeneration process is far lower than producing new catalysts. The regeneration process mainly consumes some common chemical reagents and energy, such as emulsifiers, dilute sulfuric acid, potassium molybdate, vanadium oxalate, and other chemicals, as well as electricity and gas. Compared to purchasing new catalysts, the regeneration process can significantly reduce the production costs for enterprises. Detailed Implementation

[0026] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0027] Example 1 S1: The deactivated low-temperature denitrification catalyst was recovered and ground in a ball mill at 400 r / min for 12 h until the catalyst particle size was ≤425 μm. The resulting catalyst particles were subjected to a low-temperature plasma reaction for 3 h at a voltage of 75 kV. The volume ratio of the mixed gas was SO2 / H2S / air = 25%:15%:60%. The activated catalyst particles were mixed with an emulsifier and a 0.3 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 4:1 and stirred for 0.5 h. The volume ratio of the emulsifier to the dilute sulfuric acid was 1:1. The mixture was then ultrasonically reacted for 15 min and filtered to obtain the pretreated catalyst particles. The emulsifier components are, by mass percentage: 30% polyethylene glycol 2000, 10% sodium dodecylbenzenesulfonate, 10% citric acid, 10% disodium ethylenediaminetetraacetate, 20% nano silica dispersion (solid content 20%), 5% isopropanol, and 25% deionized water. S2: The pretreated catalyst particles were mixed with a 0.25 mol / L potassium molybdate solution at a liquid-solid ratio of 3:1 and impregnated in three stages: the first stage was impregnation at room temperature for 30 min; the second stage was impregnation at 60℃ for 60 min after heating at 2℃ / min; the third stage was impregnation at 80℃ for 90 min after adding a vanadium oxalate solution with a concentration of 0.10 mol / L. S3: After the impregnation is completed, the catalyst particles are dried at 110℃ for 16h and then transferred to a muffle furnace for processing according to the following procedure: the first stage is to heat up from room temperature to 200℃ at 5℃ / min and calcine for 2h; the second stage is to heat up to 450℃ at 3℃ / min and calcine for 3h; the third stage is to cool down naturally to 150℃ and then passivate by introducing NH3 / N2 mixed gas with a volume ratio of 1:9 for 4h.

[0028] S4: The passivated catalyst particles are mixed with 3% glycerol and 3mm glass fiber in a mass ratio of 4:1:1. The mixture is then pressed into a honeycomb catalyst preform using a vacuum extruder. The preform has a pore density of 400cpsi and a wall thickness of 0.8mm. S5: The prepared catalyst preform was dried using infrared-hot air coupled drying technology. The infrared radiation drying temperature range was 60℃, and the hot air drying temperature range was 100℃. After drying, it was transferred to a muffle furnace and heated to 500℃ at 2℃ / min for 4 hours to obtain the regenerated catalyst.

[0029] Example 2 S1: The deactivated low-temperature denitrification catalyst was recovered and ground in a ball mill at 400 r / min for 8 h until the catalyst particle size was ≤425 μm. The resulting catalyst particles were subjected to a low-temperature plasma reaction for 2.5 h at a voltage of 75 kV. The volume ratio of the mixed gas was SO2 / H2S / air = 20%:10%:70%. The activated catalyst particles were then mixed with an emulsifier and a 0.1 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 4:1 and stirred for 0.5 h. The volume ratio of the emulsifier to the dilute sulfuric acid was 1:2. The mixture was then ultrasonically reacted for 10 min and filtered to obtain the pretreated catalyst particles. The emulsifier components are, by mass percentage: 30% polyethylene glycol 2000, 10% sodium dodecylbenzenesulfonate, 10% citric acid, 10% disodium ethylenediaminetetraacetate, 20% nano silica dispersion (solid content 20%), 5% isopropanol, and 25% deionized water. S2: The pretreated catalyst particles were mixed with a 0.25 mol / L potassium molybdate solution at a liquid-solid ratio of 3:1 and impregnated in three stages: the first stage was impregnation at room temperature for 30 min; the second stage was impregnation at 60℃ for 60 min after heating at 2℃ / min; the third stage was impregnation at 80℃ for 90 min after adding a vanadium oxalate solution with a concentration of 0.08 mol / L. S3: After the impregnation is completed, the catalyst particles are dried at 110℃ for 12 hours and then transferred to a muffle furnace for processing according to the following procedure: the first stage is to heat up from room temperature to 200℃ at 5℃ / min and calcine for 1 hour; the second stage is to heat up to 450℃ at 3℃ / min and calcine for 3 hours; the third stage is to cool down naturally to 150℃ and then passivate by introducing NH3 / N2 mixed gas with a volume ratio of 1:9 for 3 hours.

[0030] S4: The passivated catalyst particles are mixed with 2% glycerol by mass and 1 mm glass fiber by length, with a mass ratio of 4:1:1. The mixture is then pressed into a honeycomb catalyst preform by a vacuum extruder. The preform has a pore density of 400 cpsi and a wall thickness of 0.8 mm. S5: The prepared catalyst preform was dried using infrared-hot air coupled drying technology. The infrared radiation drying temperature range was 50℃, and the hot air drying temperature range was 90℃. After drying, it was transferred to a muffle furnace and heated to 500℃ at 2℃ / min for 4 hours to obtain the regenerated catalyst.

[0031] Example 3 S1: The deactivated low-temperature denitrification catalyst was recovered and ground in a ball mill at 400 r / min for 12 h until the catalyst particle size was ≤425 μm. The ground catalyst particles were subjected to low-temperature plasma reaction for 3 h at a voltage of 75 kV and a mixed gas volume ratio of SO2 / H2S / air = 30%:15%:55%. The activated catalyst particles were mixed with emulsifier and a 0.3 mol / L dilute sulfuric acid solution at a liquid-solid ratio of 4:1 and stirred for 1 h. The volume ratio of emulsifier to dilute sulfuric acid was 1:1. The mixture was then ultrasonically reacted for 15 min and filtered to obtain the pretreated catalyst particles. The emulsifier components are, by mass percentage: 30% polyethylene glycol 2000, 10% sodium dodecylbenzenesulfonate, 10% citric acid, 10% disodium ethylenediaminetetraacetate, 20% nano silica dispersion (solid content 20%), 5% isopropanol, and 25% deionized water. S2: The pretreated catalyst particles were mixed with a 0.25 mol / L potassium molybdate solution at a liquid-solid ratio of 3:1 and impregnated in three stages: the first stage was impregnation at room temperature for 30 min; the second stage was impregnation at 60℃ for 60 min after heating at 2℃ / min; the third stage was impregnation at 80℃ for 90 min after adding a vanadium oxalate solution with a concentration of 0.15 mol / L. S3: After the impregnation is completed, the catalyst particles are dried at 110℃ for 16h and then transferred to a muffle furnace for processing according to the following procedure: the first stage is to heat up from room temperature to 200℃ at 5℃ / min and calcine for 2h; the second stage is to heat up to 450℃ at 3℃ / min and calcine for 3h; the third stage is to cool down naturally to 150℃ and then passivate by introducing NH3 / N2 mixed gas with a volume ratio of 1:9 for 4h.

[0032] S4: The passivated catalyst particles are mixed with 5% glycerol and 5mm glass fiber in a mass ratio of 4:1:1. The mixture is then pressed into a honeycomb catalyst preform using a vacuum extruder. The preform has a pore density of 400cpsi and a wall thickness of 0.8mm. S5: The prepared catalyst preform was dried using infrared-hot air coupled drying technology. The infrared radiation drying temperature range was 70℃, and the hot air drying temperature range was 110℃. After drying, it was transferred to a muffle furnace and heated to 500℃ at 2℃ / min for 4 hours to obtain the regenerated catalyst.

[0033] Comparative Example 1 In this comparative example, only polyethylene glycol 2000 was used as an emulsifier; the remaining steps were the same as in Example 1.

[0034] Comparative Example 2 In this comparative example, the third-stage vanadium oxalate solution impregnation was not performed in step S2, and the remaining steps were the same as in Example 1.

[0035] Comparative Example 3 In this comparative example, glycerol was not added in step S4, and the remaining steps were the same as in Example 1.

[0036] Comparative Example 4 In this comparative example, no glass fiber was added in step S4, and the remaining steps were the same as in Example 1.

[0037] The denitrification efficiency and mechanical strength of the regenerated catalysts in the above embodiments and comparative examples were tested. Denitrification efficiency determination: The simulated flue gas composition was NOx, NH3, O2, and N2, with a space velocity of 10000 h⁻¹. -1 The NOx concentration was 1500 mg / m³. 3 The NH3 / NOx molar ratio was 1:1.03, the O2 concentration was 17%, the water content was 12%, and the reaction temperature was controlled between 100 and 250°C. The flow rates of each gas were controlled by a mass flow meter. Before entering the reactor, the gas was mixed by a gas mixer and then preheated by a preheater. The NOx concentrations at the inlet and outlet were measured by a flue gas analyzer. To eliminate the influence of other environmental factors, the system started collecting data and testing 60 minutes after it had been running stably for a period of time.

[0038] The mechanical strength of catalysts was tested according to standard GB / T 38219-2019. The test results are summarized in the table below.

[0039] The experimental data above show that Examples 1-3 exhibited high NOx conversion rates and good mechanical strength at different temperatures, with Example 1 showing the best performance. This indicates that the regenerated catalyst prepared according to the complete process flow has excellent performance. Compared with the examples, the NOx conversion rates and mechanical strengths of the comparative examples decreased. Comparative Example 1 used only a single emulsifier, resulting in poor pretreatment and affecting subsequent performance; Comparative Example 2 lacked vanadium oxalate impregnation, leading to incomplete loading of the active component; Comparative Example 3 did not add glycerol, and Comparative Example 4 did not add glass fiber, which affected the interparticle bonding and the structural strength of the honeycomb preform, respectively, resulting in reduced mechanical strength. This indicates that the emulsifier composition, impregnation step, and the addition of glycerol and glass fiber in this invention play a key synergistic role in the denitrification efficiency and mechanical strength of the regenerated catalyst, and the complete process is a necessary condition to ensure the excellent performance of the regenerated catalyst.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A process for regenerating a deactivated low-temperature denitrification catalyst, characterized in that, The regeneration process includes the following steps: S1: The deactivated low-temperature denitrification catalyst is recovered and ground in a ball mill at 400 r / min for 8-12 h until the catalyst particle size is ≤425 μm. The ground catalyst particles are subjected to low-temperature plasma reaction for 2.5-3 h in an atmosphere of SO2 / H2S / air mixture. The activated catalyst particles are mixed with emulsifier and dilute sulfuric acid solution at a liquid-solid ratio of 4:1 and stirred for 0.5-1 h. Then, the mixture is ultrasonically reacted for 10-15 min and filtered to obtain the pretreated catalyst particles. The emulsifier components are, by mass percentage: 30% polyethylene glycol 2000, 10% sodium dodecylbenzenesulfonate, 10% citric acid, 10% disodium ethylenediaminetetraacetate, 20% nano silica dispersion, 5% isopropanol, and 25% deionized water. S2: The pretreated catalyst particles were mixed with a 0.25 mol / L potassium molybdate solution at a liquid-solid ratio of 3:1 and impregnated in three stages: the first stage was impregnation at room temperature for 30 min; the second stage was impregnation at 60°C after heating at 2°C / min for 60 min; the third stage was impregnation at 80°C after adding vanadium oxalate solution and heating at 1°C / min for 90 min. S3: After the impregnation is completed, the catalyst particles are dried at 110℃ for 12-16 hours and then transferred to a muffle furnace for processing according to the following procedure: First stage: the temperature is increased from room temperature to 200℃ at 5℃ / min and calcined for 1-2 hours; Second stage: the temperature is increased to 450℃ at 3℃ / min and calcined for 3 hours; Third stage: after natural cooling to 150℃, NH3 / N2 mixed gas is introduced for passivation treatment, and the passivation treatment time is 3-4 hours. S4: The passivated catalyst particles are mixed with glycerol and glass fiber in a mass ratio of 4:1:1 and pressed into a honeycomb catalyst preform by a vacuum extruder. The catalyst preform has a pore density of 400 cpsi and a wall thickness of 0.8 mm. S5: The prepared catalyst preform was dried using infrared-hot air coupled drying technology. After drying, it was transferred to a muffle furnace and heated to 500℃ at 2℃ / min for 4 hours to obtain the regenerated catalyst.

2. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The low-temperature plasma reaction parameters in S1 are: voltage 75kV, and mixed gas volume ratio of SO2 / H2S / air = (20~30%):(10~15%):(55~70%).

3. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The concentration of dilute sulfuric acid in S1 is 0.1~0.3 mol / L.

4. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, In the S1 mixture of emulsifier and dilute sulfuric acid, the volume ratio of emulsifier to dilute sulfuric acid is 1:(1~2).

5. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The solid content of the nano-silica dispersion in the emulsifier in S1 is 20%.

6. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The concentration range of the vanadium oxalate solution in the third stage of S2 is 0.08~0.15 mol / L.

7. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The volume ratio of NH3 / N2 mixed gas in S3 is 1:

9.

8. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The mass fraction of glycerol in S4 is 2-5%.

9. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The length of the glass fiber in S5 ranges from 1 to 5 mm.

10. The regeneration process for a deactivated low-temperature denitrification catalyst according to claim 1, characterized in that, The infrared radiation drying temperature range of S5 is 50~70℃, and the hot air drying temperature range is 90~110℃.

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