An SCR catalyst with gradient distribution of tungsten and vanadium and a regeneration loading method thereof
By using stepwise impregnation and partial drying to form a tungsten-vanadium gradient distribution in the SCR catalyst, the problem of achieving gradient distribution in traditional impregnation processes is solved, thus improving the overall performance and lifespan of the catalyst.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU XIRE ENERGY SAVING ENVIRONMENTAL PROTECTION TECH CO LTD
- Filing Date
- 2026-04-02
- Publication Date
- 2026-06-30
Smart Images
Figure CN122298393A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of industrial catalysts and regeneration technology, specifically relating to an SCR catalyst that achieves a tungsten-vanadium gradient distribution and its regeneration loading method. Background Technology
[0002] The performance of SCR catalysts depends not only on the total amount of active components, but also on their dispersion state, chemical morphology, and spatial distribution on the TiO2 support surface. Traditional impregnation-drying-calcination processes typically result in a random or nearly uniform distribution of active components on the support.
[0003] Nitrogen oxides (NOx) and ammonia (NH3) need to diffuse from the gas phase to the active sites. If highly reactive vanadium species are excessively concentrated deep within the pores, reactants may be largely consumed at the inlet before reaching the active sites, resulting in low utilization of the internal sites. Conversely, if vanadium species are excessively enriched on the outer surface, while this facilitates reactant contact, it may exacerbate side reactions (such as SO2 oxidation) and make the catalyst susceptible to fly ash erosion and physical blockage. Poisons such as SO2 and alkali metals typically penetrate from the outer surface of the catalyst. Placing some sulfur-resistant components (such as WO3, or introduced Ce and Mo) closer to the outer surface can act as a "sacrificial layer" or "buffer layer," protecting the core vanadium active sites. Simultaneously, WO3 can inhibit the crystal transformation (from anatase to rutile phase) and grain growth of the TiO2 support, and its gradient distribution within the support framework helps improve overall thermal stability. Although the concept of gradient distribution has significant advantages, achieving a controllable and repeatable gradient distribution on an industrial scale, especially during catalyst regeneration, faces considerable challenges. Limitations of traditional impregnation processes: Single-stage co-impregnation cannot generate a gradient; in sequential impregnation, if thorough drying occurs between two impregnations, the solution from the second impregnation is unlikely to effectively penetrate the already loaded drying channels, easily resulting in a "stacked" rather than a "gradient" effect. Existing technologies primarily focus on the type and concentration of metal salts, while insufficient research is conducted on the roles of additives such as dispersants, viscosity modifiers, and surface tension modifiers in the impregnation solution. These additives, however, have a decisive influence on the adsorption behavior of precursors within the channels and the migration resistance during the drying process.
[0004] To address the aforementioned issues, it is necessary to propose a rationally designed and effective SCR catalyst for achieving a tungsten-vanadium gradient distribution and its regeneration loading method. Summary of the Invention
[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide an SCR catalyst for achieving tungsten-vanadium gradient distribution and a method for regenerating and loading the catalyst thereon.
[0006] One aspect of the present invention provides a method for regenerating and loading an SCR catalyst to achieve a tungsten-vanadium gradient distribution, the method comprising: Step 1: Pre-treat the SCR catalyst; Step 2: Immerse the pretreated SCR catalyst in the tungsten-based active impregnation solution for impregnation, and drain off excess droplets after impregnation. Step 3: Place the drained SCR catalyst in a drying oven for partial drying so that the residual moisture in the pores of the SCR catalyst forms a continuous water film on the inner wall of the pores. Step 4: Immerse the dried SCR catalyst in a vanadium-based active impregnation solution for impregnation. Step 5: Dry and calcine the SCR catalyst that has undergone two impregnations; among which, The order of steps two and four can be adjusted.
[0007] Optionally, the composition of the vanadium component active impregnation solution includes, by mass percentage: Ammonium metavanadate, 1.0%~5.0%; oxalic acid, 1.0%~4.0%; citric acid or tartaric acid, 0.5%~3.0%; cerium nitrate, ammonium molybdate or a mixture thereof, 0.1%~2.0%; nonionic surfactant, 0.05%~0.3%; viscosity modifier, 0~0.5%; balance deionized water.
[0008] Optionally, the pH value of the vanadium component active impregnation solution is controlled between 2.5 and 4.5.
[0009] Optionally, the active impregnation solution for tungsten components may include citric acid or tartaric acid.
[0010] Optionally, in step three, the drained SCR catalyst is placed in a drying oven for partial drying, including: Place the drained SCR catalyst in a drying oven at a temperature of 90℃~100℃. By monitoring the weight loss of the SCR catalyst or using a near-infrared moisture analyzer for online monitoring, the residual moisture content of the SCR catalyst can be controlled between 8% and 15%.
[0011] Optionally, in step two, the pretreated SCR catalyst is immersed in a tungsten-based active impregnation solution for impregnation, including: The pretreated SCR catalyst was immersed in a tungsten-based active impregnation solution at a temperature of 20℃~50℃ for 30min~60min.
[0012] Optionally, in step four, the dried SCR catalyst is immersed in a vanadium-based active impregnation solution for impregnation, including: The dried SCR catalyst was immersed in a vanadium-based active impregnation solution for 20 to 40 minutes.
[0013] Optionally, in step five, the SCR catalyst that has undergone two impregnations will be dried and calcined, including: The SCR catalyst was dried using a stepped heating method; The roasting process is carried out in air, with the temperature increased to 400℃~450℃ at a rate of 1℃ / min~3℃ / min, and then held at that temperature for 3h~6h.
[0014] Optionally, in step one, the SCR catalyst is pretreated, including: The SCR catalyst is cleaned to ensure that the physical blockage of the catalyst module's pores is basically removed, surface chemical poisons are effectively removed, and the catalyst is completely dried.
[0015] Another aspect of the present invention provides an SCR catalyst for achieving a tungsten-vanadium gradient distribution, which is prepared by the SCR catalyst regeneration and loading method for achieving a tungsten-vanadium gradient distribution described above.
[0016] The present invention relates to an SCR catalyst with tungsten-vanadium gradient distribution and a method for regenerating and loading the catalyst. In this method, the pretreated SCR catalyst is immersed in a first impregnation solution (tungsten liquid) and then partially dried so that the residual water in the pores of the SCR catalyst forms a continuous water film on the inner wall of the pores. Because of the residual continuous water film in the pores, the impregnation solution will gradually penetrate into the second impregnation solution (vanadium liquid) through diffusion during the second impregnation, thus forming an SCR catalyst with tungsten-vanadium gradient distribution. Because the active sites on the outer surface are easily accessible and exhibit good low-temperature activity, while the internal active sites maintain high utilization at high temperatures, high denitrification efficiency is maintained from 250℃ to 400℃. The controllable vanadium concentration in the outer layer effectively inhibits the unnecessary conversion of SO2 to SO3, with typical values decreasing from ~1.2% in homogeneous catalysts to below 0.6%. The gradient distribution of WO3 better stabilizes the support structure, and after aging at 600℃ with 10% water vapor for 100 hours, the specific surface area loss rate and activity decrease rate are both lower than those of the homogeneous distribution sample. When using the outer vanadium and inner tungsten mode, the outer vanadium layer acts as a sacrificial layer to some extent, slowing down the penetration rate of alkali metals into the internal key active regions. This method can significantly improve the overall performance of the regenerated catalyst, extend its service life, and endow it with resistance to specific poisoning, possessing significant technical value and economic benefits. Attached Figure Description
[0017] Figure 1 This is a schematic flowchart of a method for regenerating and loading an SCR catalyst to achieve a tungsten-vanadium gradient distribution, according to an embodiment of the present invention. Detailed Implementation
[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0019] like Figure 1 As shown, one aspect of the present invention provides a method for regenerating and loading an SCR catalyst to achieve a tungsten-vanadium gradient distribution, the method comprising: Step 1: Pre-treat the SCR catalyst.
[0020] Specifically, the pretreatment method for the SCR catalyst in this application can refer to the pretreatment methods for SCR catalysts in the prior art. The SCR catalyst needs to be cleaned to ensure that the physical blockage of the catalyst module's pores is basically removed, surface chemical poisons are effectively removed, and it is then completely dried.
[0021] Step 2: Immerse the pretreated SCR catalyst in the tungsten-based active impregnation solution for impregnation, and drain off excess droplets after impregnation.
[0022] To achieve tungsten-vanadium gradient loading, particularly to suppress harmful migration during drying, promote gradient formation, and improve the dispersion of the active component, this invention provides a tungsten-component active impregnation solution, which is an aqueous solution comprising, by mass percentage: Main active metal source: ammonium metavanadate, 1.0%~5.0%.
[0023] Complexing agent and stabilizer: Oxalic acid, 1.0%~4.0%. Forms a stable blue vanadate-oxalic acid complex [VO(Ox)2]² with ammonium metavanadate. - This prevents vanadium from precipitating prematurely under acidic conditions.
[0024] Gradient forming aid and dispersant: Citric acid or tartaric acid, 0.5%~3.0%. This component is one of the key additives. Its multidentate ligand structure can weakly interact with vanadium complexes or adsorb onto the support surface, changing the interfacial energy and effectively hindering the migration of vanadium species with moisture during drying, "anchoring" them in situ. It adjusts the overall pH of the impregnation solution and generates mild competitive adsorption with vanadium oxalate complex ions at the hydroxyl sites on the support surface, making the adsorption process more gradual and conducive to the formation of a gradient rather than a steep front. During calcination, the decomposition of organic acids produces gases, which helps to form a more porous active layer.
[0025] Antisulfur / catalytic co-component: Cerium nitrate, ammonium molybdate, or a mixture of both, 0.1%~2.0%. The introduction of Ce or Mo species, which synergize with V and W, can further enhance the low-temperature activity and antisulfur performance of the catalyst. They can be mixed with V and W at the molecular level during impregnation.
[0026] Penetrating and wetting agent: Nonionic surfactant, such as JFC penetrant, 0.05%~0.3%. Reduces the surface tension of the impregnation solution, improves its wettability on the partially dried catalyst, and ensures that the second impregnation solution can quickly and uniformly penetrate into the pores.
[0027] Viscosity modifier (optional): a small amount of polyvinylpyrrolidone (PVP, molecular weight approximately 10,000) or polyethylene glycol (PEG, molecular weight approximately 400), 0~0.5%. Slightly increases viscosity and further inhibits migration.
[0028] Solvent: Deionized water, balance.
[0029] The pH value of the active impregnation solution for this tungsten component is usually controlled between 2.5 and 4.5, which provides good storage stability and operational safety.
[0030] The specific process of step two can be as follows: The pretreated SCR catalyst was immersed in a tungsten-based active impregnation solution at a temperature of 20℃~50℃ for 30min~60min. After impregnation, excess droplets were drained.
[0031] Step 3: Place the drained SCR catalyst in a drying oven for partial drying, so that the residual moisture in the pores of the SCR catalyst forms a continuous water film on the inner wall of the pores.
[0032] Step three may specifically include: The drained SCR catalyst was placed in a drying oven at a temperature of 90℃~100℃.
[0033] By monitoring the weight loss of the SCR catalyst or using a near-infrared moisture analyzer for online monitoring, the residual moisture content of the SCR catalyst can be controlled between 8% and 15%.
[0034] The purpose of drying is not to completely dry the catalyst, but to evaporate the free water in its internal pore network, while intentionally retaining some residual moisture in the form of bound water or capillary condensate. The drying temperature should be relatively low to avoid rapid decomposition or migration of the active component precursor salt, typically 90℃~100℃. The drying time is dynamically adjusted according to the module size and initial moisture content, aiming to achieve the target residual moisture content.
[0035] The residual moisture forms a thin, continuous water film on the inner wall of the SCR catalyst pores. This water film has multiple functions: (1) It keeps the pores moist, providing a channel for the entry and penetration of the second impregnation solution, avoiding the hydrophobic obstruction of the dry pores; (2) It acts as a transport medium, but because of its small amount and strong hydrogen bonding with the support surface, its fluidity is much lower than that of free water, which can significantly suppress the strong capillary migration effect caused by solvent flow during the subsequent drying process; (3) This water film has dissolved part of the first loaded tungsten precursor, forming a specific local chemical environment.
[0036] Step four: Immerse the dried SCR catalyst in a vanadium-based active impregnation solution.
[0037] Specifically, the catalyst, after intermediate controlled drying, is rapidly immersed in a vanadium-based active impregnation solution. Due to the presence of a residual water film within the pores, the vanadium-based active impregnation solution gradually penetrates through diffusion. Since the tungsten precursor has partially occupied the surface sites, and the local chemical environment (e.g., pH, ionic strength) of the residual water film differs from that of the bulk impregnation solution, the adsorption process of the vanadium precursor (e.g., vanadium oxalate complex) is regulated. Its adsorption rate and capacity differ from the outer to the inner end of the pores, thus naturally forming a concentration gradient. The impregnation time is typically 20-40 minutes. The tungsten-based active impregnation solution includes citric acid or tartaric acid.
[0038] Step 5: Dry and calcine the SCR catalyst that has undergone two impregnations.
[0039] Specifically, after the SCR catalyst has undergone two impregnations and been drained, it undergoes final drying and calcination. Final drying can be achieved using a stepped heating method, for example, first removing most of the free water at 80°C, then slowly increasing to 120°C to ensure complete drying. The calcination process is carried out in air, increasing the temperature to 400°C–450°C at a rate of 1°C / min–3°C / min, and holding at this temperature for 3–6 hours, causing the metal salt to decompose into the corresponding oxides and firmly adhere to the support.
[0040] It should be noted that the order of steps two and four can be adjusted in this method. That is, the first impregnation can be performed with the vanadium component active impregnation solution, and the second impregnation can be performed with the tungsten component active impregnation solution, thus achieving different gradient modes.
[0041] The first gradient mode (vanadium on the outside, tungsten on the inside, sulfur-resistant): The pores are first impregnated with a tungsten-based active impregnating solution, then dried until the residual moisture content is ~10%, followed by impregnation with a vanadium-based active impregnating solution. This ultimately creates a complementary gradient where the tungsten content is high inside the pores, decreasing from the inside out, while the vanadium content increases from the inside out. The vanadium-rich outer layer ensures high activity, while the tungsten-rich inner layer enhances thermal stability and sulfur-resistant buffering capacity.
[0042] The second gradient mode (inner vanadium, outer tungsten, high-activity type): first impregnate with vanadium component active impregnation solution, followed by light drying (residual moisture >12%), and then impregnate with tungsten component active impregnation solution. Tungsten species tend to deposit on the outside of the channels, forming a certain coating, which can physically protect the internal vanadium sites and inhibit SO2 oxidation.
[0043] The third gradient mode (two-layer gradient, synergistic): constructs a finer distribution through a more complex combination of multi-step impregnation and intermediate drying.
[0044] The SCR catalyst with tungsten-vanadium gradient distribution prepared by the method of the present invention and the impregnation solution can be characterized by cross-sectional elemental distribution through scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS) line scanning or electron probe microanalysis (EPMA), which can intuitively show the gradient trend of W and V.
[0045] The present invention provides a method for regenerating and loading an SCR catalyst with a tungsten-vanadium gradient distribution. After immersing the pretreated SCR catalyst in a first impregnation solution (tungsten liquid) for impregnation, it is partially dried so that the residual water in the pores of the SCR catalyst forms a continuous water film on the inner wall of the pores. Due to the presence of the residual continuous water film in the pores, the impregnation solution will gradually penetrate into the second impregnation solution (vanadium liquid) through diffusion during the second impregnation, thus forming an SCR catalyst with a tungsten-vanadium gradient distribution. Because the active sites on the outer surface are easily accessible and exhibit good low-temperature activity, while the internal active sites maintain high utilization at high temperatures, high denitrification efficiency is maintained from 250℃ to 400℃. The controllable vanadium concentration in the outer layer effectively inhibits the unnecessary conversion of SO2 to SO3, with typical values decreasing from ~1.2% in homogeneous catalysts to below 0.6%. The gradient distribution of WO3 better stabilizes the support structure, and after aging at 600℃ with 10% water vapor for 100 hours, the specific surface area loss rate and activity decrease rate are both lower than those of the homogeneous distribution sample. When using the outer vanadium and inner tungsten mode, the outer vanadium layer acts as a sacrificial layer to some extent, slowing down the penetration rate of alkali metals into the internal key active regions. This method can significantly improve the overall performance of the regenerated catalyst, extend its service life, and endow it with resistance to specific poisoning, possessing significant technical value and economic benefits.
[0046] Another aspect of the present invention provides an SCR catalyst achieving a tungsten-vanadium gradient distribution, which is prepared using the aforementioned method for regenerating and loading an SCR catalyst to achieve a tungsten-vanadium gradient distribution. The specific process of this method for regenerating and loading an SCR catalyst to achieve a tungsten-vanadium gradient distribution has been described in detail above and will not be repeated here.
[0047] The following examples illustrate the specific process of the SCR catalyst regeneration and loading method for achieving a tungsten-vanadium gradient distribution according to the present invention. In each of the following examples, the catalyst support is a honeycomb TiO2-WO3 matrix with dimensions of 150mm × 150mm × 980mm and 20 pores.
[0048] Example 1 Pretreatment: Take a cleaned and thoroughly dried deactivated SCR catalyst module (initial V2O5≈0.3%, WO3≈2.5%).
[0049] First impregnation (W load): Prepare a tungsten component active impregnation solution: 12% ammonium tungstate solution with 1% citric acid added. Immerse the SCR catalyst module in the solution and maintain it at 50°C for 40 minutes, then remove and drain for 10 minutes.
[0050] Intermediate controlled drying: Place the module in a forced-air drying oven and set it to 90℃. Weigh it every 5 minutes. When the weight reaches 108% of the initial dry weight (after pretreatment) (i.e., the residual moisture is about 8%), remove it immediately.
[0051] Second impregnation (V-load): Preparation of vanadium component active impregnation solution: Add ammonium metavanadate (3.0%), oxalic acid (2.4%, molar ratio approximately 1:2), citric acid (1.8%), cerium nitrate (0.5%), and JFC penetrant (0.1%) to deionized water, and stir until completely dissolved and clear, pH≈3.2. Immerse the intermediate-dried module in this vanadium impregnation solution and maintain at room temperature (25℃) for 30 minutes, then remove and drain. First dry at 100℃ for 2 hours, then increase the temperature to 400℃ at a program of 2℃ / min and calcine for 4 hours, then cool with the furnace.
[0052] Characterization and testing: Activity evaluation: Under simulated flue gas conditions (NO 500ppm, NH3 500ppm, O2 5%, SO2 1000ppm, H2O 8%, N2 equilibrium, space velocity 4000h), - The test was conducted in ¹). It reached 96.5% at 300℃ and maintained 89.2% at 250℃. SO2 oxidation rate: only 0.58% at 300℃.
[0053] Comparative experiment: A co-impregnation solution was prepared using the same total amount of ammonium tungstate and ammonium metavanadate, and the same batch of pretreatment modules were impregnated in a single batch under identical conditions. The resulting catalyst exhibited essentially uniform W and V distributions. Its performance: 94.1% denitrification efficiency at 300℃, and 1.25% SO2 oxidation rate.
[0054] Example 2 With other conditions fixed as in Example 1, catalyst samples with residual moisture content of 5%, 10% (Example 1), and 15% were prepared by changing only the intermediate controlled drying endpoint.
[0055] 5% residual moisture: The gradient effect is weak, the vanadium penetration is slightly insufficient, and the low-temperature activity is slightly low (efficiency of 85.1% at 250℃).
[0056] 10% residual moisture: A clear gradient and optimal overall performance. 15% residual moisture: During the second impregnation, there is more free water in the pores, vanadium migration intensifies during drying, the gradient effect deteriorates, and the SO2 oxidation rate increases to 0.82%. Conclusion: The optimal window is a residual moisture content within the range of 8%-12%.
[0057] Example 3 Prepare two vanadium impregnation solutions: Liquid A (comparative example): Contains only ammonium metavanadate (3.0%) and oxalic acid (2.4%).
[0058] Liquid B (in this invention): contains ammonium metavanadate (3.0%), oxalic acid (2.4%), and citric acid (1.8%).
[0059] The second impregnation was used in the process of Example 1, and the residual moisture content during the intermediate drying was fixed at 10%.
[0060] The SO2 oxidation rate using the catalyst with liquid B (0.58%) was significantly lower than that using the catalyst with liquid A (1.05%).
[0061] Example 4 The gradient-distributed catalyst and the uniformly distributed control catalyst prepared in Example 1 were placed in air containing 10% water vapor and aged at 600°C for 100 hours. Specific surface area change: the gradient-distributed catalyst decreased from 43.5 m² / g to 39.8 m² / g (loss of 8.5%); the uniformly distributed catalyst decreased from 42.9 m² / g to 36.1 m² / g (loss of 15.9%). Activity retention: after aging, the denitrification efficiency at 300°C decreased from 96.5% to 93.8% for the gradient-distributed catalyst (retention rate of 97.2%); and from 94.1% to 87.5% for the uniformly distributed catalyst (retention rate of 93.0%).
[0062] As can be seen from the above, compared with the catalyst regenerated by the traditional uniform impregnation method, the SCR catalyst regeneration and loading method of the present invention that achieves tungsten-vanadium gradient distribution has the following beneficial effects: 1) Wider active temperature window: Because the active sites on the outer surface are easily accessible, the activity is good at low temperatures; the active sites on the inner surface still have a high utilization rate at high temperatures, so the denitrification efficiency is maintained from 250℃ to 400℃.
[0063] 2) Significantly reduced SO2 oxidation rate: The controllable vanadium concentration in the outer layer effectively suppresses the unnecessary conversion of SO2 to SO3, with typical values decreasing from ~1.2% in a homogeneous catalyst to below 0.6%.
[0064] 3) Enhanced resistance to hydrothermal aging: The gradient distribution of WO3 better stabilizes the carrier structure. After aging at 600℃ and 10% water vapor for 100 hours, the specific surface area loss rate and activity decrease rate are both lower than those of the uniformly distributed sample.
[0065] 4) Improved resistance to alkali metal poisoning: When the outer vanadium and inner tungsten mode is adopted, the outer vanadium layer acts as a sacrificial layer to a certain extent, which slows down the penetration rate of alkali metals into the internal key active areas.
[0066] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.
Claims
1. A method for regenerating and loading an SCR catalyst to achieve a tungsten-vanadium gradient distribution, characterized in that, The method includes: Step 1: Pre-treat the SCR catalyst; Step 2: Immerse the pretreated SCR catalyst in the tungsten-based active impregnation solution for impregnation, and drain off excess droplets after impregnation. Step 3: Place the drained SCR catalyst in a drying oven for partial drying so that the residual moisture in the pores of the SCR catalyst forms a continuous water film on the inner wall of the pores. Step 4: Immerse the dried SCR catalyst in a vanadium-based active impregnation solution for impregnation. Step 5: Dry and calcine the SCR catalyst that has undergone two impregnations; among which, The order of steps two and four can be adjusted.
2. The method according to claim 1, characterized in that, The vanadium component active impregnation solution comprises, by mass percentage: Ammonium metavanadate, 1.0%~5.0%; oxalic acid, 1.0%~4.0%; citric acid or tartaric acid, 0.5%~3.0%; cerium nitrate, ammonium molybdate or a mixture thereof, 0.1%~2.0%; nonionic surfactant, 0.05%~0.3%; viscosity modifier, 0~0.5%; balance deionized water.
3. The method according to claim 2, characterized in that, The pH value of the vanadium component active impregnation solution is controlled between 2.5 and 4.
5.
4. The method according to claim 1, characterized in that, The active impregnation solution for tungsten components includes citric acid or tartaric acid.
5. The method according to claim 1, characterized in that, In step three, the drained SCR catalyst is placed in a drying oven for partial drying, including: Place the drained SCR catalyst in a drying oven at a temperature of 90℃~100℃. By monitoring the weight loss of the SCR catalyst or using a near-infrared moisture analyzer for online monitoring, the residual moisture content of the SCR catalyst can be controlled between 8% and 15%.
6. The method according to claim 1, characterized in that, Step two involves immersing the pretreated SCR catalyst in a tungsten-based active impregnation solution, including: The pretreated SCR catalyst was immersed in a tungsten-based active impregnation solution at a temperature of 20℃~50℃ for 30min~60min.
7. The method according to claim 1, characterized in that, Step four involves immersing the dried SCR catalyst in a vanadium-based active impregnation solution for impregnation, including: The dried SCR catalyst was immersed in a vanadium-based active impregnation solution for 20 to 40 minutes.
8. The method according to claim 1, characterized in that, Step five involves drying and calcining the SCR catalyst that has undergone two impregnations, including: The SCR catalyst was dried using a stepped heating method; The roasting process is carried out in air, with the temperature increased to 400℃~450℃ at a rate of 1℃ / min~3℃ / min, and then held at that temperature for 3h~6h.
9. The method according to claim 1, characterized in that, Step one involves pretreating the SCR catalyst, including: The SCR catalyst is cleaned to ensure that the physical blockage of the catalyst module's pores is basically removed, surface chemical poisons are effectively removed, and the catalyst is completely dried.
10. An SCR catalyst for achieving a tungsten-vanadium gradient distribution, characterized in that, It is prepared by the SCR catalyst regeneration and loading method for achieving tungsten-vanadium gradient distribution as described in any one of claims 1 to 9.