Process for the regeneration of deactivated denitration catalysts

Abstract

The present application relates to the technical field of catalyst regeneration, and discloses a regeneration method of deactivated denitration catalysts. The regeneration method comprises the following steps: (1) performing at least one heat treatment on the deactivated denitration catalyst monomer; (2) placing the deactivated denitration catalyst monomer after heat treatment in an electrolyte solution for electrochemical treatment, and then performing rinsing; (3) placing the deactivated denitration catalyst monomer after rinsing in a mechanical reinforcement solution and an active component supplement solution in sequence for impregnation; and (4) performing oxidation calcination on the deactivated denitration catalyst monomer after impregnation, and then performing reduction. The method can perform overall regeneration on the deactivated denitration catalysts caused by metal elements such as Fe, Pb, Cu and As, organic matters such as COD, and hydrogen sulfate ammonium type miscellaneous salts, the regenerated denitration catalyst obtained can maintain the integrity of the structure, has higher mechanical strength and catalytic activity, and can be directly put into use.

Description

Technical Field

[0001] This invention relates to the field of catalyst regeneration technology, and more specifically to a method for regenerating a deactivated denitrification catalyst. Background Technology

[0002] Selective catalytic reduction (SCR) denitrification technology is currently the most mature flue gas denitrification technology and has been widely used in ultra-low emission retrofitting across various industries. As the core of SCR denitrification technology, the SCR catalyst used can become deactivated during use due to blockage, wear, sintering, chemical poisoning, and loss of active components, rendering it unusable. If deactivated denitrification catalysts are not properly disposed of, it will cause serious resource waste and environmental pollution. Currently, the country is vigorously promoting the regeneration of deactivated denitrification catalysts to achieve efficient recycling.

[0003] Currently, for collected deactivated denitration catalysts (vanadium-titanium based), those with intact structures and good mechanical strength should be prioritized for overall regeneration to obtain regenerated denitration catalysts; for deactivated denitration catalysts whose overall structure has been damaged, valuable metals should be recovered. However, many current regeneration and disposal processes for deactivated denitration catalysts do not follow this recovery principle. The regeneration process often damages the original overall structure and reduces mechanical strength, rendering the catalyst unusable and severely limiting its service life.

[0004] In addition, deactivated denitration catalysts containing multiple heavy metal elements, high heavy metal content, organic matter, and miscellaneous salts such as ammonium bisulfate are difficult to regenerate. Currently, there is no suitable method to completely remove these substances that cause deactivation of the denitration catalyst, which cannot meet the actual working conditions' requirements for the activity of regenerated denitration catalysts. Summary of the Invention

[0005] The purpose of this invention is to overcome the difficulties in the integral regeneration of deactivated catalysts with high heavy metal content and many types of impurities in existing technologies, as well as the low mechanical strength and catalytic activity of the regenerated catalysts. This invention provides a method for regenerating deactivated denitration catalysts. This method can integrally regenerate deactivated denitration catalysts with high heavy metal content and containing various organic compounds and ammonium bisulfate. The regenerated denitration catalyst maintains its structural integrity without damaging its overall structure, and possesses higher mechanical strength and catalytic activity, allowing for direct use and achieving efficient recycling of the deactivated denitration catalyst.

[0006] To achieve the above objectives, the present invention provides a method for regenerating a deactivated denitrification catalyst, the regeneration method comprising the following steps:

[0007] (1) The deactivated denitrification catalyst monomer is subjected to at least one heat treatment;

[0008] (2) The deactivated denitrification catalyst monomer after heat treatment is placed in an electrolyte solution for electrochemical treatment, followed by rinsing;

[0009] (3) The rinsed deactivated denitrification catalyst monomers were placed in mechanical reinforcing solution and active component replenishment solution for immersion in sequentially;

[0010] (4) The impregnated deactivated denitrification catalyst monomer is oxidized and calcined, and then reduced;

[0011] The electrolyte in the electrolyte solution is selected from one or more of citric acid, oxalic acid, lactic acid, tartaric acid, ammonium citrate, ammonium oxalate, ammonium lactate, and ammonium tartrate.

[0012] The conditions for the electrochemical treatment include: a current density of 10-50 mA / cm². 2 The time is 0.5-3 hours;

[0013] The mechanical reinforcing liquid is selected from one or more of ethoxy tantalum solution, nano-silicon dispersion, and waterborne polyurethane.

[0014] Preferably, the concentration of the electrolyte in the electrolyte solution is 0.01-0.5 mol / L.

[0015] Preferably, the electrolyte solution further contains an initiator;

[0016] And / or, the initiator is selected from one or more of hydrogen peroxide, sodium hypochlorite, and sodium persulfate.

[0017] Preferably, the concentration of the initiator in the electrolyte solution is 1-5 wt%.

[0018] Preferably, the heat treatment conditions include: a temperature of 300-500℃ and a time of 2-5 minutes;

[0019] And / or, the heat treatment is performed 2-3 times.

[0020] Preferably, when the mechanical reinforcing liquid is an ethoxytantalum solution, the concentration of ethoxytantalum in the ethoxytantalum solution is 10-60 wt%.

[0021] And / or, when the mechanical reinforcing liquid is a nano-silicon dispersion, the concentration of SiO2 in the nano-silicon dispersion is 20-50 wt%;

[0022] And / or, when the mechanical reinforcing liquid is an aqueous polyurethane, the concentration of polyurethane in the aqueous polyurethane is 20-50 wt%.

[0023] Preferably, the active component replenishment solution contains an active component and an auxiliary agent. The active component is one or more of a tungsten source, a molybdenum source, and a vanadium source, and the auxiliary agent is selected from one or more of a cerium salt, a manganese salt, a cobalt salt, an antimony salt, a copper salt, and a holmium salt.

[0024] Preferably, based on the total weight of the active component replenishment solution, the content of the active component is 0.1-3 wt%, and the content of the adjuvant is 0.1-3 wt%.

[0025] Preferably, the conditions for the oxidation calcination include: heating to 250-350℃ and holding at that temperature for 240-300 min, then heating to 420-460℃ and holding at that temperature for 150-200 min, and then heating to 520-570℃ and holding at that temperature for 100-150 min.

[0026] Preferably, the reduction temperature is 250-350℃, and the reduction time is 4.5-7 hours;

[0027] And / or, the reducing atmosphere is a mixture of H2 and a protective gas or a mixture of CO and a protective gas;

[0028] And / or, when the reducing atmosphere is a mixture of H2 and a protective gas, the volume fraction of H2 in the mixture is 1-5 vol%.

[0029] And / or, when the reducing atmosphere is a mixture of CO and a protective gas, the volume fraction of CO in the mixture is 1-5 vol%.

[0030] The regeneration method described in this invention enables the overall regeneration of deactivated denitration catalysts with high heavy metal content, organic matter, and ammonium bisulfate content. It achieves efficient removal of heavy metals such as Fe, Pb, Cu, and As, organic matter such as COD, and ammonium bisulfate impurities from the deactivated denitration catalyst through heat treatment, electrochemical treatment, and oxidative calcination. Furthermore, by sequentially immersing the deactivated denitration catalyst monomers in mechanical reinforcing liquid and active component replenishing liquid, the mechanical strength and catalytic activity of the catalyst are replenished and enhanced. Further reduction enhances catalyst activation, thus achieving the regeneration of the deactivated denitration catalyst. The regenerated denitration catalyst maintains its overall structure and exhibits high mechanical strength and catalytic activity, making it ready for direct use. Detailed Implementation

[0031] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0033] The regeneration method for the deactivated denitration catalyst of the present invention includes the following steps:

[0034] (1) The deactivated denitrification catalyst monomer is subjected to at least one heat treatment;

[0035] (2) The deactivated denitrification catalyst monomer after heat treatment is placed in an electrolyte solution for electrochemical treatment, followed by rinsing;

[0036] (3) The rinsed deactivated denitrification catalyst monomers were placed in mechanical reinforcing solution and active component replenishment solution for immersion in sequentially;

[0037] (4) The impregnated deactivated denitrification catalyst monomer is oxidized and calcined, and then reduced.

[0038] In this invention, the deactivated denitrification catalyst monomer refers to a denitrification catalyst monomer obtained from the deactivated denitrification catalyst module whose mechanical strength meets the regenerable standard, and whose overall structure remains intact. The structure of the denitrification catalyst monomer can be honeycomb-like.

[0039] In this invention, the regenerated deactivated denitration catalyst contains various heavy metal elements that can poison denitration catalysts, such as Fe, Pb, Cu, and As, as well as various alkali metals, such as K and Na. Furthermore, a large amount of organic matter adheres to the surface of the deactivated denitration catalyst, which can also reduce its activity. In addition, the surface of the deactivated denitration catalyst also contains a large amount of NH4HSO4 mixed salts. These substances increase the difficulty of regenerating the deactivated denitration catalyst, and existing technologies struggle to completely remove these poisoning substances while preserving the overall structure of the deactivated denitration catalyst. The method described in this invention employs multiple synergistic approaches to clean and regenerate the deactivated denitration catalyst. While ensuring that the original mechanical strength of the denitration catalyst is not reduced, the poisoning substances are thoroughly removed, enabling the regenerated denitration catalyst to possess the same excellent catalytic activity and maintain its overall structure, allowing it to be directly put into use.

[0040] In the method described in this invention, the deactivated denitrification catalyst monomer contains 0.1-0.8 wt% Fe, 0.01-0.07 wt% As, 0.1-0.2 wt% Pb, 0.01-0.1 wt% Cu, 4-6 wt% organic matter, and 4-6 wt% ammonium bisulfate.

[0041] In a specific implementation, before separating the deactivated denitrification catalyst monomers from the deactivated denitrification catalyst module, the deactivated denitrification catalyst module can be cleaned with compressed air at 0.3-0.7 MPa to remove fly ash from the surface and pores of the deactivated denitrification catalyst module as much as possible.

[0042] In the method described in this invention, the deactivated denitrification catalyst monomer is subjected to at least one heat treatment in order to decompose the ammonium bisulfate and organic matter such as COD attached to the surface and pores of the deactivated denitrification catalyst monomer, so as to avoid affecting subsequent processing.

[0043] In a preferred embodiment, the heat treatment conditions in step (1) include: a temperature of 300-500°C, preferably 350-450°C, and a time of 2-5 minutes. More preferably, during the heat treatment, compressed air at 0.3-0.7 MPa can also be used for purging.

[0044] In a preferred embodiment, the heat treatment is performed 2-3 times in step (1). The conditions for each heat treatment can be the same or different, but it is preferred that the conditions for each heat treatment are the same.

[0045] In a specific implementation, in order to further improve the effect of electrochemical treatment in step (2), before electrochemical treatment, the deactivated denitrification catalyst monomer after heat treatment can be subjected to high-pressure rinsing at a pressure of 8-16 MPa and a rinsing time of 15-20 min. After rinsing, it is placed in an electrolyte solution for electrochemical treatment.

[0046] In the method described in this invention, the specific process of the electrochemical treatment includes: placing the heat-treated deactivated denitrification catalyst monomer in an electrolyte solution, with both the anode and cathode using DSA electrodes, wherein the anode is located at the bottom of the electrolytic cell and the cathode is located at the top of the electrolytic cell, and then applying electricity for treatment.

[0047] In the method described in this invention, oxygen and a large number of hydroxyl radicals (·OH) are generated on the anode plate at the bottom of the electrolytic cell through electrochemical treatment. The generated hydroxyl radicals help to deeply oxidize residual organic matter such as COD on the surface of the deactivated denitrification catalyst monomer into CO2 and water, thereby further removing organic matter attached to the surface of the deactivated denitrification catalyst monomer. At the same time, it can also promote the oxidation of AsO3. 3- Converted to AsO43- This improves the efficiency of arsenic removal. On the other hand, during the electrochemical treatment process, by controlling the current density and electrolysis time, the Fe content in the deactivated denitrification catalyst monomer is reduced. 3 + Pb 2+ Cu 2+ Under the influence of the electric field, ions move towards the cathode at the top of the tank and are enriched in the cathode region by OH groups. - Ion capture, thereby forming a water-insoluble hydroxide, achieves the removal of Fe from the deactivated denitrification catalyst. 3+ Pb 2+ Cu 2+ The efficient removal of metal elements avoids Fe 3+ Pb 2+ Cu 2+ The large amount of residual metal ions negatively impacts the activity of the regenerated denitration catalyst. In this invention, the deactivated denitration catalyst is treated electrochemically to remove organic matter and As adhering to its surface. Furthermore, by controlling the electrochemical treatment process, the Fe adsorbed on the surface can also be removed. 3+ Pb 2+ Cu 2+ The efficient removal of metal elements significantly reduces reagent consumption during the regeneration process. At the same time, it can effectively avoid the loss of active components such as vanadium and tungsten and the decline in the original mechanical strength of the catalyst caused by the use of strong acids and alkalis.

[0048] In the method described in this invention, organic matter attached to the surface of the deactivated denitration catalyst is deeply removed by an electrochemical method. Unlike the heat treatment and other methods commonly used in the prior art, the method described in this invention avoids the energy consumption generated during the heat treatment process, and avoids the catalyst sintering phenomenon caused by heat treatment and the adverse effects on the catalyst strength and activity, thus ensuring the complete regeneration of the deactivated denitration catalyst and the activity requirements after regeneration.

[0049] In the method described in this invention, the electrolyte in the electrolyte solution is selected from one or more of citric acid, oxalic acid, lactic acid, tartaric acid, ammonium citrate, ammonium oxalate, ammonium lactate, and ammonium tartrate. By selecting a milder electrolyte solution, damage to the overall structure of the deactivated denitrification catalyst monomer can be avoided during the treatment process, and its original mechanical strength can be maintained as much as possible so that it can be put into use directly after regeneration.

[0050] In a preferred embodiment, the concentration of the electrolyte in the electrolyte solution is 0.01-0.5 mol / L, preferably 0.2-0.3 mol / L. Specifically, the concentration of the electrolyte in the electrolyte solution can be 0.01 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, or 0.5 mol / L.

[0051] In a specific implementation, the conditions for the electrochemical treatment include: a current density of 10-50 mA / cm². 2 Preferably 25-35 mA / cm 2 The treatment time is 0.5-3 hours, preferably 1.5-2.5 hours. In this invention, by controlling the current density used in the electrochemical treatment process, the large amount of Fe adsorbed on the surface of the deactivated denitrification catalyst monomer can be reduced. 3+ Pb 2+ Cu 2+ Under the pull of the electric field, it moves towards the cathode of the electrolytic cell, and is then exposed to OH- at the cathode. - Ion capture forms a precipitate for removal, improving the removal rate of heavy metals such as Fe, Pb, and Cu in the deactivated denitration catalyst, ensuring that the catalytic activity of the regenerated denitration catalyst is not affected, and it can be put into use directly after regeneration.

[0052] In a preferred embodiment, a small amount of initiator can be added to the electrolyte during the electrochemical treatment process. The added initiator promotes the generation of more hydroxyl radicals during electrolysis, thereby achieving a more thorough removal of COD organic matter adhering to the surface of the deactivated denitrification catalyst, facilitating subsequent activation implantation. Simultaneously, it avoids the mechanical and structural damage caused by heat treatment in existing technologies. Preferably, the initiator is selected from one or more of hydrogen peroxide, sodium hypochlorite, and sodium persulfate.

[0053] In a preferred embodiment, the concentration of the initiator in the electrolyte solution is 1-5 wt%, preferably 2.5-3.8 wt%. Specifically, the concentration of the initiator in the electrolyte solution can be 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0054] In a specific implementation, ultrasonic treatment can be used in conjunction with electrochemical treatment to improve the removal effect. The frequency of the ultrasonic waves can be 10-80kHz.

[0055] In the method described in this invention, in step (2), the deactivated denitrification catalyst monomer after electrochemical treatment is bubble-washed with process water for 10-30 minutes. The amount of air introduced should ensure that the catalyst monomer is fully impacted by the air bubbles, generally 0.1-1 m.3 / min.

[0056] In the method described in this invention, in step (3), the rinsed deactivated denitration catalyst is immersed in a mechanical reinforcing liquid, which can significantly improve the mechanical strength and service life of the regenerated denitration catalyst. Specifically, the mechanical reinforcing liquid is selected from one or more of ethoxytantalum solution, nano-silica dispersion, and aqueous polyurethane, preferably ethoxytantalum solution and aqueous polyurethane. Using ethoxytantalum solution and aqueous polyurethane can significantly enhance the mechanical strength of the regenerated denitration catalyst.

[0057] In specific embodiments, the nano-silicon dispersion can be an acidic nano-silicon dispersion, a neutral nano-silicon dispersion, an alkaline ammonia-type nano-silicon dispersion, an alkaline sodium-type nano-silicon dispersion, or an alkaline potassium-type nano-silicon dispersion, preferably a neutral nano-silicon dispersion or an alkaline ammonia-type nano-silicon dispersion. Specifically, the nano-silicon dispersion can be a conventional commercially available product.

[0058] In a preferred embodiment, when the mechanical reinforcing liquid is an ethoxytantalum solution, the concentration of ethoxytantalum in the ethoxytantalum solution is 10-60 wt%, preferably 20-40%. Specifically, the concentration of ethoxytantalum in the ethoxytantalum solution can be 20 wt%, 30 wt%, or 40 wt%. When the mechanical reinforcing liquid is a nano-silicon dispersion, the concentration of SiO2 in the nano-silicon dispersion is 20-50 wt%, specifically, the concentration of SiO2 in the nano-silicon dispersion can be 20 wt%, 30 wt%, 40 wt%, or 50 wt%. When the mechanical reinforcing liquid is an aqueous polyurethane, the concentration of polyurethane in the aqueous polyurethane is 20-50 wt%, preferably 30-40%. Specifically, the concentration of polyurethane in the aqueous polyurethane can be 20 wt%, 30 wt%, 40 wt%, or 50 wt%.

[0059] In the method described in this invention, in step (3), the deactivated denitrification catalyst that has been impregnated in the mechanical reinforcing liquid is taken out, dried by blowing air, and then impregnated in the active component replenishment liquid to further restore its catalytic activity.

[0060] In the method described in this invention, the active component replenishment solution refers to a substance used to replenish the active components contained in the deactivated denitration catalyst monomer, so as to facilitate the restoration of the activity of the deactivated denitration catalyst.

[0061] In a specific implementation, the immersion time in the active ingredient replenishment solution is 30-200 min, and the immersion temperature is 40-80℃.

[0062] In a preferred embodiment, the active component replenishment solution contains an active component and an auxiliary agent. The active component is a tungsten source, a molybdenum source, and / or a vanadium source, and is one or more of the tungsten, molybdenum, and vanadium sources. Preferably, the tungsten source is ammonium paratungstate, the molybdenum source is ammonium heptamolybdate, and the vanadium source is ammonium metavanadate.

[0063] In a preferred embodiment, the cerium salt, manganese salt, cobalt salt, antimony salt, copper salt, and holmium salt are all soluble salts. Specifically, the cerium salt can be cerium nitrate, the manganese salt can be manganese nitrate, the cobalt salt can be cobalt nitrate, the antimony salt can be antimony nitrate, the copper salt can be copper nitrate, and the holmium salt can be holmium nitrate.

[0064] In a specific embodiment, in order to facilitate better dissolution of the active components and additives in the active component replenishment solution, the active component replenishment solution also contains a co-solvent, which is selected from one or more of oxalic acid, monoethanolamine, ammonia and dimethyl sulfoxide.

[0065] In a preferred embodiment, based on the total weight of the active component replenishment solution, the content of the active component is 0.1-3 wt%, preferably 0.2-1.5 wt%, and the content of the adjuvant is 0.1-3 wt%, preferably 1.5-2.5 wt%. Specifically, the content of the active component can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%; the content of the adjuvant can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, or 3 wt%.

[0066] In a specific implementation, the deactivated denitrification catalyst monomer after active impregnation is washed, dried, and then oxidized and calcined. The oxidative calcination promotes the conversion of the active component precursor (salt) into the corresponding oxide.

[0067] In a preferred embodiment, the oxidation calcination conditions include: heating to 250-350°C and holding at that temperature for 240-300 minutes, then heating to 420-460°C and holding at that temperature for 150-200 minutes, and then heating to 520-570°C and holding at that temperature for 100-150 minutes. The atmosphere for the oxidation calcination can be air or a mixture of oxygen and a protective gas.

[0068] In the method described in this invention, the deactivated denitration catalyst monomer after oxidation and calcination is reduced and activated to further improve its catalytic activity, thereby obtaining a regenerated denitration catalyst.

[0069] In the method described in this invention, the catalytic activity of the obtained regenerated denitrification catalyst is improved by controlling the conditions of the reduction process. Preferably, the reduction temperature is 250-350℃, more preferably 280-320℃; the reduction time is 4.5-7h, more preferably 5-6h. Specifically, the reduction temperature can be 280℃, 300℃, 310℃, 320℃, or 350℃; the reduction time can be 5h, 5.5h, or 6h.

[0070] In a preferred embodiment, the reducing atmosphere is a mixture of H2 and a protective gas or a mixture of CO and a protective gas. Preferably, when the reducing atmosphere is a mixture of H2 and a protective gas, the volume fraction of H2 in the mixture is 1-5 vol%; when the reducing atmosphere is a mixture of CO and a protective gas, the volume fraction of CO in the mixture is 1-5 vol%.

[0071] In the method described in this invention, no step in the regeneration process of the deactivated denitration catalyst can be omitted. Each step in the process is closely related and works together to remove the substances and metal elements that deactivated the denitration catalyst, thereby realizing the regeneration process of the deactivated denitration catalyst.

[0072] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto.

[0073] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0074] The regenerated deactivated denitrification catalyst monomers in the following examples and comparative examples contain 0.5 wt% Fe, 0.05 wt% As, 0.15 wt% Pb, 0.05 wt% Cu, 4.5 wt% organic matter, and 4.5 wt% ammonium bisulfate.

[0075] Example 1

[0076] (1) The deactivated denitrification catalyst module was cleaned with 0.5MPa compressed air. Then, the deactivated denitrification catalyst monomer with complete structure was sorted out and the deactivated denitrification catalyst monomer was heat-treated twice with a flame gun. The temperature of each heat treatment was 400℃ and the time of each heat treatment was 3min. At the same time, 0.5MPa compressed air was used for purging during the heat treatment.

[0077] (2) The deactivated denitrification catalyst monomers after heat treatment were subjected to high-pressure cleaning with process water at a pressure of 10 MPa for 15 minutes. After cleaning, they were vertically placed into an electrochemical auxiliary cleaning tank for electrochemical treatment. The electrolyte was an ammonium citrate solution (0.2 mol / L) containing hydrogen peroxide as an initiator (3 wt%). Both the cathode and anode were DSA electrodes, with a current density of 30 mA / cm². 2 The electrolysis time is 2 hours; after the electrochemical treatment, the mixture is rinsed with process water for 20 minutes, and the amount of air bubbled in is 0.5 m³. 3 / min;

[0078] (3) The washed deactivated denitration catalyst monomer was immersed in a mechanical reinforcing solution (neutral nano-silicon dispersion, SiO2 concentration 30wt%) for 20min, then removed and dried and immersed in an active component replenishing solution (active component is ammonium metavanadate, auxiliary agent is cerium nitrate, where the concentration of ammonium metavanadate is 0.5wt%, the concentration of cerium nitrate is 1.0wt%, and the co-solvent is ammonia water) for 120min at an immersion temperature of 50℃.

[0079] (4) The deactivated denitration catalyst monomer impregnated in the active component replenishment solution is oxidized and calcined in air. The oxidation and calcination process is as follows: the temperature is raised to 300℃ and held for 255 min, then raised to 450℃ and held for 170 min, then raised to 550℃ and held for 120 min, and then cooled to room temperature. Then the denitration catalyst monomer after oxidation and calcination is reduced in a mixed atmosphere of H2 and nitrogen (H2 volume fraction is 3 vol%). The reduction temperature is 300℃ and the reduction time is 330 min. After the reduction is completed, the regenerated denitration catalyst is obtained.

[0080] Example 2

[0081] (1) The deactivated denitrification catalyst module was cleaned with 0.5MPa compressed air. Then, the deactivated denitrification catalyst monomer with complete structure was sorted out and the deactivated denitrification catalyst monomer was heat-treated twice with a flame gun. The temperature of each heat treatment was 400℃ and the time of each heat treatment was 3min. At the same time, 0.5MPa compressed air was used for purging during the heat treatment.

[0082] (2) The deactivated denitrification catalyst monomers after heat treatment were subjected to high-pressure cleaning with process water at a pressure of 10 MPa for 15 min. After cleaning, they were vertically placed into an electrochemical auxiliary cleaning tank for electrochemical treatment. The electrolyte was a citric acid solution (0.2 mol / L) containing sodium persulfate (3.5 wt%) as an initiator. Both the cathode and anode were DSA electrodes with a current density of 35 mA / cm². 2 The electrolysis time was 2.5 hours; after the electrochemical treatment, the cells were rinsed with process water for 20 minutes, and the amount of air introduced was 0.5 m³. 3 / min;

[0083] (3) The deactivated denitrification catalyst monomer after rinsing was immersed in mechanical reinforcing solution (ethoxytantalum solution, ethoxytantalum concentration 30wt%) for 20min, then removed and dried and immersed in active component replenishment solution (active component is ammonium metavanadate, auxiliary agent is manganese nitrate, where the concentration of ammonium metavanadate is 0.5wt%, the concentration of manganese nitrate is 1.5wt%, and the co-solvent is oxalic acid) for 120min at an immersion temperature of 50℃.

[0084] (4) The deactivated denitration catalyst monomer impregnated in the active component replenishment solution is oxidized and calcined in air. The oxidation and calcination process is as follows: the temperature is raised to 280℃ and held for 260 min, then the temperature is raised to 455℃ and held for 180 min, then the temperature is raised to 550℃ and held for 125 min, and then the temperature is lowered to room temperature. Then the denitration catalyst monomer after oxidation and calcination is reduced in a mixed atmosphere of H2 and nitrogen (H2 volume fraction is 3 vol%). The reduction temperature is 320℃ and the reduction time is 300 min. After the reduction is completed, the regenerated denitration catalyst is obtained.

[0085] Example 3

[0086] (1) The deactivated denitrification catalyst module was cleaned with 0.5MPa compressed air. Then, the deactivated denitrification catalyst monomer with complete structure was sorted out and the deactivated denitrification catalyst monomer was heat-treated twice with a flame gun. The temperature of each heat treatment was 400℃ and the time of each heat treatment was 3min. At the same time, 0.5MPa compressed air was used for purging during the heat treatment.

[0087] (2) The deactivated denitrification catalyst monomers after heat treatment were subjected to high-pressure cleaning with process water at a pressure of 10 MPa for 15 min. After cleaning, they were vertically placed into an electrochemical auxiliary cleaning tank for electrochemical treatment. The electrolyte was an oxalic acid solution (0.2 mol / L) containing sodium hypochlorite (3.8 wt%) as an initiator. Both the cathode and anode were DSA electrodes with a current density of 32 mA / cm². 2 The electrolysis time was 2.4 hours; after the electrochemical treatment, the cells were rinsed with process water for 20 minutes, and the amount of air bubbled in was 0.5 m³. 3 / min;

[0088] (3) The deactivated denitrification catalyst monomer after rinsing was immersed in mechanical reinforcing liquid (aqueous polyurethane, polyurethane concentration 30wt%) for 20min, then removed and dried and immersed in active component replenishing liquid (active component is ammonium metavanadate, auxiliary agent is cobalt nitrate, wherein the concentration of ammonium metavanadate is 0.5wt%, the concentration of cobalt nitrate is 2wt%, and the co-solvent is oxalic acid) for 120min at an immersion temperature of 50℃.

[0089] (4) The deactivated denitration catalyst monomer impregnated in the active component replenishment solution is oxidized and calcined in air. The oxidation and calcination process is as follows: the temperature is raised to 320℃ and held for 260 min, then raised to 455℃ and held for 180 min, then raised to 555℃ and held for 135 min, and then cooled to room temperature. Then the denitration catalyst monomer after oxidation and calcination is reduced in a mixed atmosphere of CO and argon (the volume fraction of CO is 3.5 vol%). The reduction temperature is 290℃ and the reduction time is 350 min. After the reduction is completed, the regenerated denitration catalyst is obtained.

[0090] Comparative Example 1

[0091] The method was implemented according to Example 1, except that a 0.2 mol / L NaOH solution was used as the electrolyte in the electrochemical treatment process.

[0092] Comparative Example 2

[0093] The procedure was carried out according to Example 1, except that the current density during the electrochemical treatment was 5 mA / cm². 2 .

[0094] Comparative Example 3

[0095] The procedure was carried out according to Example 1, except that the current density during the electrochemical treatment was 55 mA / cm². 2 .

[0096] Comparative Example 4

[0097] The method of Example 1 was implemented, except that in step (3), the deactivated denitrification catalyst monomer after rinsing was not immersed in the mechanical reinforcing liquid, but was directly immersed in the active component replenishing liquid.

[0098] Comparative Example 5

[0099] The method of Example 1 was implemented, except that in step (4), no reduction activation was performed after oxidation and calcination.

[0100] Comparative Example 6

[0101] The method of Example 1 was implemented, except that hydrogen peroxide initiator was not added in step (2).

[0102] Test case

[0103] Test Example 1

[0104] The contents of heavy metals (Fe, As, Pb, Cu), organic matter, and ammonium bisulfate in the regenerated denitrification catalysts obtained in Examples 1-3 and Comparative Examples 1-6 were detected, and the corresponding removal rates were calculated. The results are shown in Table 1.

[0105] The formulas for calculating the removal rate of Fe element are: (Fe element content in deactivated denitrification catalyst monomer - Fe element content in regenerated denitrification catalyst) ÷ Fe element content in deactivated denitrification catalyst monomer × 100%; the formulas for calculating the removal rate of As element are: (As element content in deactivated denitrification catalyst monomer - As element content in regenerated denitrification catalyst) ÷ As element content in deactivated denitrification catalyst monomer × 100%; the formulas for calculating the removal rate of Pb element are: (Pb element content in deactivated denitrification catalyst monomer - Pb element content in regenerated denitrification catalyst) ÷ Pb element content in deactivated denitrification catalyst monomer × 100%; and the formulas for calculating the removal rate of Cu element are: (Cu element content in deactivated denitrification catalyst monomer - Cu element content in regenerated denitrification catalyst) ÷ Cu element content in deactivated denitrification catalyst monomer × 100%.

[0106] The formula for calculating the organic matter removal rate is: (organic matter content in deactivated denitrification catalyst monomer - organic matter content in regenerated denitrification catalyst) ÷ organic matter content in deactivated denitrification catalyst monomer × 100%;

[0107] The formula for calculating the removal rate of ammonium bisulfate is: (Ammonium bisulfate content in the deactivated denitrification catalyst monomer - Ammonium bisulfate content in the regenerated denitrification catalyst) ÷ Ammonium bisulfate content in the deactivated denitrification catalyst monomer × 100%.

[0108] Table 1

[0109]

[0110] As shown in Table 1, the method described in this invention can remove various heavy metals, organic matter, and ammonium bisulfate with significant removal effect. While ensuring the integrity of the overall structure of the regenerated denitrification catalyst, it maximizes the removal of poisoned substances from the denitrification catalyst.

[0111] Test Example 2

[0112] The mechanical properties and denitrification efficiency of the denitrification catalysts obtained by regeneration in Examples 1-3 and Comparative Examples 1-6 were tested, and the results are shown in Table 2.

[0113] Compressive strength: determined according to the method of GB / T 31587.

[0114] Denitrification efficiency: determined according to GB / T 31587, with a flue gas temperature of 380℃ and a flue gas volume space velocity of 3000 h⁻¹. -1 The denitrification efficiency is calculated as follows: (NOx concentration at reactor inlet - NOx concentration at reactor outlet) / NOx concentration at reactor inlet × 100%.

[0115] Table 2

[0116]

[0117] As can be seen from the results in Table 2, the method of the present invention can successfully regenerate the deactivated denitration catalyst, and the regenerated denitration catalyst has excellent catalytic performance and complete structure, and can be directly put into use, showing great application prospects.

[0118] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for regenerating a deactivated denitration catalyst, characterized in that, The regeneration method includes the following steps: (1) The deactivated denitration catalyst monomer is subjected to at least one heat treatment; (2) The deactivated denitration catalyst monomer after heat treatment is placed in an electrolyte solution for electrochemical treatment, followed by rinsing; (3) The deactivated denitrification catalyst monomers after rinsing are placed in mechanical reinforcing solution and active component replenishment solution for immersion in sequence; (4) The impregnated deactivated denitrification catalyst monomer is oxidized and calcined, and then reduced; The electrolyte in the electrolyte solution is selected from one or more of citric acid, oxalic acid, lactic acid, tartaric acid, ammonium citrate, ammonium oxalate, ammonium lactate, and ammonium tartrate. The conditions for the electrochemical treatment include: a current density of 10-50 mA / cm². 2 The time is 0.5-3 hours; The mechanical reinforcing liquid is selected from one or more of ethoxy tantalum solution, nano-silicon dispersion, and waterborne polyurethane. The electrolyte solution also contains an initiator, which is selected from one or more of hydrogen peroxide, sodium hypochlorite, and sodium persulfate.

2. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, The concentration of the electrolyte in the electrolyte solution is 0.01-0.5 mol / L.

3. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, The concentration of the initiator in the electrolyte solution is 1-5 wt%.

4. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, The heat treatment conditions include: a temperature of 300-500℃ and a time of 2-5 minutes; And / or, the heat treatment is performed 2-3 times.

5. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, When the mechanical reinforcing liquid is an ethoxytantalum solution, the concentration of ethoxytantalum in the ethoxytantalum solution is 10-60 wt%. And / or, when the mechanical reinforcing liquid is a nano-silicon dispersion, the concentration of SiO2 in the nano-silicon dispersion is 20-50 wt%; And / or, when the mechanical reinforcing liquid is aqueous polyurethane, the concentration of polyurethane in the aqueous polyurethane is 20-50 wt%.

6. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, The active component replenishment solution contains an active component and an auxiliary agent. The active component is one or more of tungsten source, molybdenum source and vanadium source, and the auxiliary agent is selected from one or more of cerium salt, manganese salt, cobalt salt, antimony salt, copper salt and holmium salt.

7. The method for regenerating the deactivated denitration catalyst according to claim 6, characterized in that, Based on the total weight of the active component replenishment solution, the content of the active component is 0.1-3 wt%, and the content of the auxiliary agent is 0.1-3 wt%.

8. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, The conditions for oxidation and calcination include: heating to 250-350℃ and holding at that temperature for 240-300 min, then heating to 420-460℃ and holding at that temperature for 150-200 min, and then heating to 520-570℃ and holding at that temperature for 100-150 min.

9. The method for regenerating the deactivated denitration catalyst according to claim 1, characterized in that, The reduction temperature is 250-350℃, and the reduction time is 4.5-7h.

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