Thallium poisoning SCR (Selective Catalytic Reduction) catalyst as well as wet regeneration method and application thereof

Abstract

The invention belongs to the technical field of SCR catalyst regeneration, and relates to a thallium poisoning SCR catalyst and a wet regeneration method and application thereof, the wet regeneration method comprises the following steps: (1) exposing a thallium element attached to the surface of the catalyst and / or increasing the specific surface area of the catalyst to obtain a pretreated catalyst; (2) soaking the pretreated catalyst in an acid solution to obtain a mixture; and (3) adding an oxidizing agent and a complexing agent into the mixture, stirring to react, and separating to obtain the regenerated SCR catalyst. According to the method disclosed by the invention, the damage to active substances on the surface of the catalyst is relatively small, and active components do not need to be supplemented finally, so that the cost of the regeneration process is effectively saved, and the regeneration process is simplified; and the thallium element in the catalyst can be effectively removed while the vast majority of active components are retained, so that the activity of the poisoning catalyst is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of SCR catalyst regeneration, and relates to a thallium-poisoned SCR catalyst and a wet regeneration method and application thereof. BACKGROUND

[0002] Nitrogen oxide (NO X ) is one of the main precursors of photochemical smog, greenhouse effect, acid rain, ozone layer destruction and PM2.5, which causes great harm to the ecological system and human life. At present, the emission amount of nitrogen oxide in the cement industry is at a high level, and has become an important source of nitrogen oxide emission in China. Among various common NO X removal technologies, the selective catalytic reduction (SCR) denitration technology is the most widely used denitration technology at present because of its high denitration efficiency, good selectivity, relatively clean process and reliable technology.

[0003] The SCR catalyst is a crucial component of the SCR denitration technology. Due to the presence of ash, alkali metal and heavy metal in the kiln, the activity of the SCR catalyst will gradually decrease during use. At present, the cement kiln production line mainly uses limestone, sandstone, fly ash, clay and pyrite as raw materials, and trace amounts of thallium (Tl) are contained in these raw materials and fuel coal because Tl has lithophilic property. At high temperatures, Tl is mixed into the flue gas in a gaseous form. Since Tl is alkaline, it is easy to combine with the acidic sites on the surface of the catalyst. In addition, Tl has strong electron-donating ability, so the acidic sites of V2O5 and TiO2 on the surface of the catalyst will be covered by Tl2O3. Since Tl2O3 has high thermal stability, it will not be discharged with the flue gas in the kiln, but will continuously accumulate on the surface of the SCR catalyst, causing the activity of the catalyst to decrease until the catalyst is completely deactivated. In addition, Tl also has strong affinity for sulfur, so it will combine with SO2 in the flue gas to form Tl2SO4, which will further cover Tl2O3 on the surface of the catalyst. Ultimately, Tl is layered and covered on the surface of the catalyst in the form of Tl2O3 and Tl2SO4, causing thallium poisoning of the catalyst. In addition, this coverage will also increase the production of N2O, causing the conversion rate of nitrogen oxide to decrease, which reduces the catalytic activity.

[0004] Catalyst regeneration is the process of removing harmful impurities in the deactivated catalyst by certain means and restoring its denitration efficiency. In the current regeneration method, the application of wet cleaning has a wide range of effects and mature methods, and is widely used. The purpose of wet cleaning technology is to remove impurity elements on the surface of the catalyst by solution cleaning to restore the activity of the catalyst. For wet cleaning technology, the selection of cleaning solution is the key to the performance of catalyst regeneration. Chinese invention patent CN111715210A discloses a regeneration method of thallium-poisoned SCR denitration catalyst in a cement kiln, which uses dilute sulfuric acid and EDTA as cleaning solution to soak the poisoned catalyst, implants active elements and calcines to complete regeneration, and the denitration activity of the regenerated catalyst is low, and the regeneration effect is limited. Chinese invention patent CN112827354A discloses a regeneration method of thallium-poisoned denitration catalyst, which uses a mixed solution of dilute sulfuric acid, hypochlorous acid and ammonium acetate to soak the catalyst, then adds a hole expanding agent and an active solution, and finally dries and calcines to complete the regeneration of the catalyst. Although a regenerated catalyst with good activity is obtained, and the thallium element removal rate is also high, this method is mainly for catalysts with light poisoning degree. SUMMARY

[0005] The main purpose of the present application is to overcome the problems of low activity of the regenerated catalyst in the prior art, more loss of active components, and less removal of thallium elements, and to provide a thallium-poisoned SCR catalyst and a wet regeneration method and application thereof.

[0006] To achieve the above-mentioned purpose, the specific technical solutions are as follows: The present application provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) exposing the thallium elements attached to the surface of the thallium-poisoned SCR catalyst and / or increasing the specific surface area of the thallium-poisoned SCR catalyst to obtain a pretreated catalyst; (2) soaking the pretreated catalyst with an acid solution to obtain a mixture; the acid is selected from acetic acid; (3) adding an oxidizing agent and a complexing agent to the mixture, stirring and reacting, and then separating to obtain a regenerated SCR catalyst.

[0007] The present application first exposes the thallium elements attached to the surface of the catalyst, increases the contact area with the cleaning acid, and makes the reaction more complete; then uses the acid cleaning solution to dissolve the surface impurities and performs preliminary cleaning; adds an oxidizing agent to promote the valence change of thallium elements and make them dissolve in the solution; adds a complexing agent to combine with thallium elements and prevent thallium from combining with active sites on the surface of the catalyst; and finally separates to obtain a regenerated SCR catalyst. The wet regeneration method of thallium-poisoned SCR catalyst according to the present application effectively removes thallium elements in the catalyst while retaining most of the active components, and significantly improves the activity of the poisoned catalyst.

[0008] The application uses acetic acid as a cleaning agent, provides an acidic environment required for the reaction, and provides hydrogen ions for breaking the bond between thallium elements and catalysts; the acetate is a weak ligand and will not damage the carrier and active substance, and the active ingredient does not need to be supplemented, effectively saving the cost of the regeneration process, simplifying the regeneration process, and producing waste liquid with little environmental impact, and the price of acetic acid is relatively low, suitable for large-scale use.

[0009] Further, the thallium-poisoned SCR catalyst is a catalyst with mild poisoning, moderate poisoning or severe poisoning.

[0010] The mild poisoning refers to that the catalyst activity is about 60%-90%, and the thallium element content is 2wt% or less. The moderate poisoning refers to that the catalyst activity is about 30%-60%, and the thallium element content is 2wt%-4wt%. The severe poisoning refers to that the catalyst activity is 30% or less, and the thallium element content is 4wt%-6wt%.

[0011] The wet regeneration method of the thallium-poisoned SCR catalyst of the application can be used to regenerate catalysts with deep thallium poisoning, such as catalysts with about 6wt% thallium elements, which are almost completely deactivated at 200-500℃.

[0012] Further, the method for exposing the thallium elements attached to the surface of the catalyst comprises removing dust on the surface and in the pores of the thallium-poisoned SCR catalyst by a physical method to obtain a soot-blowing catalyst, and the physical method is compressed air soot blowing or negative pressure dust suction.

[0013] The application removes dust on the surface and in the pores of the thallium-poisoned SCR catalyst by a physical method to expose the thallium elements attached to the surface of the catalyst.

[0014] Further, the method for increasing the specific surface area of the catalyst comprises grinding the catalyst or the soot-blowing catalyst into a powder and passing it through a 200-mesh sieve.

[0015] The application grinds the catalyst or the soot-blowing catalyst to increase its contact area with the cleaning solution, so that the reaction is more complete and the efficiency is improved.

[0016] Further, in step (2), the concentration of the acid solution is 0.5-1mol / L, and the solid-liquid ratio is 1g:15-25mL.

[0017] The concentration range can ensure that the acid solution fully reacts with the catalyst, provides a suitable pH environment for thiourea complexation, and does not damage other catalyst components; the solid-liquid ratio can completely cover the catalyst powder, ensuring that the reaction proceeds fully, and more solution will increase waste liquid and increase costs.

[0018] Further, in step (2), the acid solution soaking time is 20-40 min, and the soaking temperature is 20-30℃.

[0019] Further, the oxidizing agent is selected from hydrogen peroxide.

[0020] Using hydrogen peroxide to oxidize the catalyst surface allows thallium to be oxidized from monovalent to trivalent, and the decomposition products of hydrogen peroxide are oxygen and water, which do not introduce other ions that affect the reaction, are non-corrosive, do not damage the active substances of the catalyst, have low toxicity, are much lower than other types of oxidizing agents, and have little impact on the environment.

[0021] Further, the complexing agent is selected from thiourea.

[0022] Because thallium has a strong affinity for sulfur, thiourea has strong complexing ability for high-valence heavy metal ions, and compared to other complexing agents, thiourea is more effective at removing trivalent thallium from the catalyst, and the regeneration solution is in an acidic environment, thiourea is relatively stable in acidic conditions, has low toxicity, and is environmentally friendly.

[0023] Further, the concentration of the oxidizing agent is 0.05-0.1 g / mL, and / or the concentration of the complexing agent is 0.5-1 mol / L.

[0024] The selection of the concentration range of the oxidizing agent and the complexing agent ensures that the reaction proceeds fully and avoids waste of chemical reagents.

[0025] Further, in step (3), the reaction temperature is 20-80℃, the reaction time is 40-80 min, and the stirring speed is 300-500 rpm.

[0026] The selection of the reaction temperature, time, and speed ensures that the reaction proceeds fully.

[0027] Further, in step (3), centrifugation is used for separation, the centrifugation speed is 3000-5000 rpm, and the centrifugation time is 4-6 min.

[0028] Further, in step (3), after separation, drying is performed, the drying temperature is 50-80℃, and the drying time is 10-14 h.

[0029] The application further provides a regenerated SCR catalyst prepared by the wet regeneration method of the thallium-poisoned SCR catalyst.

[0030] The application further provides a denitration method of the regenerated SCR catalyst.

[0031] Specifically, the regenerated SCR catalyst is crushed to obtain 40-60 mesh particles, and the reaction conditions are as follows: catalyst dosage is 0.15 g, total gas volume is 200-300 mL / min, NO concentration is 400-600 ppm, NH3 concentration is 400-600 ppm, O2 concentration is 4-6%, N2 is used as the supplement gas, space velocity is 90000-110000 h-1, and the denitration temperature is 300-400 DEG C. -1

[0032] Preferably, the regenerated SCR catalyst is crushed to obtain 40-60 mesh particles, and the reaction conditions are as follows: catalyst dosage is 0.15 g, total gas volume is 250 mL / min, NO concentration is 500 ppm, NH3 concentration is 500 ppm, O2 concentration is 5%, N2 is used as the supplement gas, space velocity is 100000 h-1, and the denitration temperature is 350 DEG C. -1

[0033] Compared with the prior art, the application has the following remarkable beneficial effects: The wet regeneration method of the thallium-poisoned SCR catalyst provided by the application has less damage to the active substances on the surface of the catalyst, and finally does not need to supplement the active components, effectively saves the cost of the regeneration process, simplifies the regeneration process, can effectively remove the thallium elements in the catalyst while retaining most of the active components, significantly improves the activity of the poisoned catalyst, the thallium element removal rate of the poisoned catalyst is more than 90%, the vanadium element loss rate is less than 10%, and the best denitration efficiency of the regenerated catalyst at 350 DEG C reaches 99.17%.

[0034] The wet regeneration method of the thallium-poisoned SCR catalyst provided by the application can be used for the regeneration of catalysts with higher difficulty and deeper thallium poisoning. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0036] Figure 1 ​​is a graph of the catalyst activity determination results in the inventive examples and comparative examples. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0038] In the embodiments of the present application, the specific techniques or conditions not specified are performed according to the techniques or conditions described in the literature in the art or according to the product instructions; the reagents or instruments not specified by the manufacturer are all conventional products that can be purchased through a regular channel.

[0039] Example 1 The present embodiment provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is purged with compressed air to remove the surface dust and dredge the pore channels, to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and then placed in a planetary ball mill, and after grinding for 5 minutes, it is passed through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in a 0.5 mol / L acetic acid solution, soaked at room temperature for 30 min, and then hydrogen peroxide and thiourea are added, so that the concentration of hydrogen peroxide in the mixed solution is 0.05 g / mL and the concentration of thiourea is 0.5 mol / L, and the mixture is heated and stirred in a 60℃ water bath stirring pot for 1 h, with a stirring speed of 400 rpm and a solid-liquid ratio of 1 g:20 mL; (4) The mixture in step (3) is subjected to centrifugal treatment, with a centrifugal time of 5 min and a speed of 4000 rpm, and the catalyst is separated from the waste cleaning liquid and washed with deionized water; (5) The catalyst obtained in step (4) is placed in a 60℃ oven for drying for 12 h, to obtain a regenerated catalyst.

[0040] Example 2 The present embodiment provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is purged with compressed air to remove the surface dust and dredge the pore channels, to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and then placed in a planetary ball mill, and after grinding for 5 minutes, it is passed through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in 1 mol / L acetic acid solution, soaked at room temperature for 30 min, then hydrogen peroxide and thiourea are added, so that the concentration of hydrogen peroxide in the mixed solution is 0.1 g / mL and the concentration of thiourea is 1 mol / L, and heated and stirred in a water bath stirring pot at 60°C for 1 h, with a stirring speed of 400 rpm and a solid-liquid ratio of 1 g:20 mL; (4) The mixture in step (3) is centrifuged for 5 min at a speed of 4000 rpm, and the catalyst is separated from the waste liquid and washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12 h to obtain a regenerated catalyst.

[0041] Comparative Example 1 This comparative example provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, ground for 5 minutes, and then passed through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in 0.5 mol / L acetic acid solution, soaked at room temperature for 30 min, then hydrogen peroxide is added to make the concentration of hydrogen peroxide in the solution 0.05 g / mL, and heated and stirred in a water bath stirring pot at 60°C for 1 h, with a stirring speed of 400 rpm and a solid-liquid ratio of 1 g:20 mL; (4) The mixture in step (3) is centrifuged for 5 min at a speed of 4000 rpm, and the catalyst is separated from the waste liquid and washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12 h to obtain a regenerated catalyst.

[0042] Comparative Example 2 This comparative example provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, ground for 5 minutes, and then passed through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in 0.5 mol / L acetic acid solution, soaked at room temperature for 30 min, then sulfur hydride is added to make the concentration of sulfur hydride in the solution 0.5 mol / L, and heated and stirred in a water bath at 60°C for 1 h, the stirring speed is 400 rpm, and the solid-liquid ratio is 1 g:20 mL; (4) The mixture in step (3) is centrifuged for 5 min at 4000 rpm, the catalyst is separated from the waste liquid, and then washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12 h to obtain the regenerated catalyst.

[0043] Comparative Example 3 The present comparative example provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, ground for 5 minutes, and then sieved through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in 0.5 mol / L acetic acid solution, soaked at room temperature for 30 min, then sulfur hydride is added to make the concentration of sulfur hydride in the solution 0.5 mol / L, and heated and stirred in a water bath at 60°C for 1 h, the stirring speed is 400 rpm, and the solid-liquid ratio is 1 g:20 mL; (4) The mixture in step (3) is centrifuged for 5 min at 4000 rpm, the catalyst is separated from the waste liquid, and then washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12 h to obtain the regenerated catalyst.

[0044] Comparative Example 4 The present comparative example provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, ground for 5 minutes, and then sieved through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in 0.5 mol / L acetic acid solution, soaked at room temperature for 30 min, then sulfur hydride is added to make the concentration of sulfur hydride in the solution 0.5 mol / L, and heated and stirred in a water bath at 60°C for 1 h, the stirring speed is 400 rpm, and the solid-liquid ratio is 1 g:20 mL; (4) The mixture in step (3) is subjected to centrifugal treatment for 5 min at 4000 rpm, the catalyst is separated from the cleaning waste liquid, and is washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12 h to obtain a regenerated catalyst.

[0045] Comparative Example 5 The present comparative example provides a wet regeneration method of a thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, and ground for 5 min, and then passed through a 200-mesh sieve; (3) The catalyst obtained in step (2) is soaked in deionized water at room temperature for 30 min, and then hydrogen peroxide and thiourea are added, so that the concentration of hydrogen peroxide in the mixed solution is 0.05 g / mL, and the concentration of thiourea is 0.5 mol / L, and heated and stirred in a water bath stirring pot at 60°C for 1 h, the stirring speed is 400 rpm, and the solid-liquid ratio is 1 g:20 mL; (4) The mixture in step (3) is subjected to centrifugal treatment for 5 min at 4000 rpm, the catalyst is separated from the cleaning waste liquid, and is washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12 h to obtain a regenerated catalyst.

[0046] Comparative Example 6 The present example provides a wet regeneration method of a thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, and ground for 5 min, and then passed through a 200-mesh sieve; (3) The catalyst obtained in step (2) is soaked in a 0.5 mol / L oxalic acid solution at room temperature for 30 min, and then hydrogen peroxide and thiourea are added, so that the concentration of hydrogen peroxide in the mixed solution is 0.05 g / mL, and the concentration of thiourea is 0.5 mol / L, and heated and stirred in a water bath stirring pot at 60°C for 1 h, the stirring speed is 400 rpm, and the solid-liquid ratio is 1 g:20 mL; (4) The mixture in step (3) is subjected to centrifugal treatment for 5 min at 4000 rpm, the catalyst is separated from the cleaning waste liquid, and is washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12h to obtain the regenerated catalyst.

[0047] Comparative Example 7 The present example provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, ground for 5 minutes, and then sieved through a 200-mesh sieve; (3) The catalyst obtained in step (2) is immersed in a 0.5 mol / L glycine solution at room temperature for 30 min, then hydrogen peroxide and thiourea are added, so that the final concentration of hydrogen peroxide in the mixed solution is 0.05 g / mL and the concentration of thiourea is 0.5 mol / L, and the mixture is heated and stirred in a water bath stirring pot at 60°C for 1h, with a stirring speed of 400 rpm and a solid-liquid ratio of 1g:20mL; (4) The mixture in step (3) is centrifuged for 5 min at a speed of 4000 rpm, the catalyst is separated from the waste liquid, and then washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12h to obtain the regenerated catalyst.

[0048] Comparative Example 8 The present example provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is blown with compressed air to remove the surface dust and unblock the pores to obtain a dust-blowing catalyst; (2) The dust-blowing catalyst is crushed and placed in a planetary ball mill, ground for 5 minutes, and then sieved through a 200-mesh sieve; (3) The catalyst obtained in step (2) is immersed in a 0.5 mol / L acetic acid solution at room temperature for 30 min, then hydrogen peroxide and sodium thiocyanate are added, so that the final concentration of hydrogen peroxide in the mixed solution is 0.05 g / mL and the concentration of sodium thiocyanate is 0.5 mol / L, and the mixture is heated and stirred in a water bath stirring pot at 60°C for 1h, with a stirring speed of 400 rpm and a solid-liquid ratio of 1g:20mL; (4) The mixture in step (3) is centrifuged for 5 min at a speed of 4000 rpm, the catalyst is separated from the waste liquid, and then washed with deionized water; (5) The catalyst obtained in step (4) is dried in a 60°C oven for 12h to obtain the regenerated catalyst.

[0049] Comparative Example 9 The embodiment provides a wet regeneration method of thallium-poisoned SCR catalyst, comprising the following steps: (1) The thallium-poisoned SCR catalyst is purged by compressed air to remove surface dust and dredge the pore channel, and a dust-blowing catalyst is obtained; (2) The dust-blowing catalyst is crushed and then placed in a planetary ball mill, and after being ground for 5 minutes, the catalyst is sieved through a 200-mesh sieve; (3) The catalyst obtained in step (2) is placed in a 0.5 mol / L acetic acid solution, and soaked at room temperature for 30 min, and then hydrogen peroxide and a complexing agent oxalic acid are added, so that the concentration of hydrogen peroxide in the mixed solution is 0.05 g / mL, and the concentration of oxalic acid is 0.5 mol / L, and the mixed solution is heated and stirred in a water bath stirring pot at 60 ℃ for 1 h, and the stirring speed is 400 rpm, and the solid-liquid ratio is 1 g:20 mL; (4) The mixture in step (3) is centrifuged for 5 min at a speed of 4000 rpm, and the catalyst is separated from the waste liquid and washed with deionized water; (5) The catalyst obtained in step (4) is placed in a 60 ℃ oven and dried for 12 h to obtain a regenerated catalyst.

[0050] The same batch of thallium-poisoned SCR catalyst (waste catalyst) is used in the embodiment and the comparative example, the denitration activity of the waste catalyst at 350 ℃ is 3.37%, the specific surface area (m bet 2 / g) is 49.22, the content of thallium element is 4.56 wt.%, and the content of V element is 1.32 wt.%.

[0051] The detection method of the denitration activity of the catalyst: the thallium-poisoned SCR catalyst (waste catalyst) or the regenerated catalyst is crushed to obtain 40-60 mesh particles, and the concentration of nitrogen oxides is tested by using an infrared flue gas analyzer. The reaction conditions are as follows: the catalyst dosage is 0.15 g, the NO concentration is 500 ppm, the NH3 concentration is 500 ppm, the O2 concentration is 5%, N2 is used as a supplement gas, the total gas amount is 250 mL / min, the space velocity is 100000 h -1 , and the test temperature is 350 ℃.

[0052] The element content test of the catalyst: the thallium-poisoned SCR catalyst (waste catalyst) or the regenerated catalyst is subjected to ICP-OES test.

[0053] The specific surface area test of the catalyst: the thallium-poisoned SCR catalyst (waste catalyst) or the regenerated catalyst is subjected to BET test.

[0054] The denitration activity, element content and specific surface area of the catalyst are shown in Table 1 and Figure 1 . ​

[0055] Table 1 is the regenerated catalyst element content and specific surface area determination results of each example and comparative example.

[0056] From the data in Table 1, it can be seen that the thallium element of the catalyst after regeneration treatment is effectively removed, and the thallium element removal rate of examples 1-2 reaches more than 90%, and the loss rate of vanadium element is significantly reduced compared with the sulfuric acid treatment method, effectively avoiding the loss of active components; at the same time, the specific surface area of each regenerated catalyst is increased, which proves that the method can effectively regenerate the thallium poisoned SCR catalyst and realize the recycling use of the catalyst.

[0057] As shown in the denitration activity test results in Figure 1 It can be found that the activity of the regenerated catalyst (the denitration activity of the waste catalyst at 350℃ is 3.37%) is significantly recovered, and the denitration activity of examples 1-2 after regeneration is better than that of comparative examples 1-9. The denitration activity of the regenerated catalyst obtained in example 1 at 350℃ reaches 99.17%, which has good regeneration performance.

[0058] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A wet regeneration method for a thallium-poisoned SCR catalyst, characterized in that, Includes the following steps: (1) After exposing the thallium elements attached to the surface of the thallium-poisoned SCR catalyst and / or increasing the specific surface area of ​​the thallium-poisoned SCR catalyst, a pretreated catalyst is obtained. (2) The pretreated catalyst is soaked in an acid solution to obtain a mixture; the acid is selected from acetic acid; (3) Add oxidant and complexing agent to the mixture, and separate after stirring to obtain regenerated SCR catalyst.

2. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 1, characterized in that, The thallium-poisoned SCR catalyst is a mildly, moderately, or severely poisoned catalyst.

3. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 1 or 2, characterized in that, In step (2), the concentration of the acid solution is 0.5-1 mol / L, and the solid-liquid ratio is 1 g: 15-25 mL; and / or, in step (2), the soaking time of the acid solution is 20-40 min, and the soaking temperature is 20-30℃.

4. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 3, characterized in that, The oxidant is selected from hydrogen peroxide; and / or the complexing agent is selected from thiourea.

5. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 1, 2, or 4, characterized in that, In step (3), the concentration of the oxidant is 0.05-0.1 g / mL; and / or the concentration of the complexing agent is 0.5-1 mol / L.

6. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 5, characterized in that, In step (3), the reaction temperature is 20-80℃, the reaction time is 40-80min, and the stirring speed is 300-500rpm.

7. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 1, 2, 4, or 6, characterized in that, A method for exposing thallium elements adhering to the catalyst surface: using physical methods to remove dust from the surface and pores of the thallium-poisoned SCR catalyst, wherein the physical methods are compressed air blowing or negative pressure dust suction; And / or, methods to increase the specific surface area of ​​the catalyst: grind the catalyst or soot blowing catalyst into powder and pass it through a 200-mesh sieve.

8. The wet regeneration method for thallium-poisoned SCR catalyst according to claim 1, 2, 5, or 6, characterized in that, In step (3), centrifugation is used for separation, with a centrifugation speed of 3000-5000 rpm and a centrifugation time of 4-6 min; and / or, in step (3), drying is performed after separation, with a drying temperature of 50-80℃ and a drying time of 10-14 h.

9. A regenerated SCR catalyst, characterized in that, It is prepared by the wet regeneration method of the thallium poisoned SCR catalyst as described in any one of claims 1-8.

10. A method for denitrification of a regenerated SCR catalyst, characterized in that, The regenerated SCR catalyst as described in claim 9 is used.

Images