Regeneration carrier high-doped denitration catalyst and preparation method thereof

Abstract

The application belongs to the technical field of preparation of denitration catalysts, and discloses a regenerated carrier high-mixing-ratio denitration catalyst and a preparation method thereof, which comprises, by weight fraction, 70-85 parts of high-quality regenerated titanium tungsten powder, 10-25 parts of virgin titanium dioxide, 1-5 parts of ammonium metavanadate, 1-4 parts of ammonium paratungstate, 2-6 parts of glass fiber, 0.5-2 parts of carboxymethyl cellulose, 0.1-0.5 parts of polyethylene oxide, 0.2-0.8 parts of stearic acid, 1-3 parts of citric acid and 25-40 parts of deionized water. The regenerated carrier high-mixing-ratio denitration catalyst prepared by the application has excellent catalytic activity, selectivity, mechanical strength and wear resistance, can meet the requirements of industrial flue gas denitration, realizes full quantization and high value recycling of waste SCR denitration catalysts, and reduces the discharge of hazardous waste.

Description

Technical Field

[0001] This invention belongs to the field of denitrification catalyst preparation technology, and relates to a denitrification catalyst with a high doping ratio on a regenerated support and its preparation method. Background Technology

[0002] Nitrogen oxides (NOx) in flue gas x Flue gas denitrification (FGD) is one of the major air pollutants, causing environmental problems such as acid rain, photochemical smog, and ozone layer depletion, while also severely damaging the human respiratory system. Selective catalytic reduction (SCR) technology is currently the most widely used and mature flue gas denitrification technology both domestically and internationally, and its core component is the denitrification catalyst. The service life of commonly used vanadium-tungsten-titanium-based denitrification catalysts in industry is generally 3-5 years. With the large-scale operation of denitrification units in the thermal power industry, a large amount of waste SCR denitrification catalyst is generated annually.

[0003] Waste SCR denitrification catalysts are classified as hazardous waste, containing heavy metals such as vanadium and tungsten, as well as toxic and harmful impurities such as potassium, sodium, and arsenic. Direct landfilling would not only cause severe environmental pollution but also result in a huge waste of valuable metal resources like vanadium and tungsten. Currently, the main methods for treating waste SCR denitrification catalysts are regeneration and resource utilization. Catalyst regeneration involves cleaning and restoring the activity of catalyst modules with good mechanical integrity before reuse. However, it cannot handle waste catalysts with damaged mechanical structures, severe sintering, or those whose performance cannot be restored through regeneration. Resource utilization involves grinding the waste catalyst into powder, removing impurities, and activating it to prepare regenerated titanium-tungsten powder, which is then used to produce new denitrification catalysts.

[0004] However, existing resource utilization technologies have the following problems: First, the waste catalyst contains many types of impurities with high content and large fluctuations in composition, making it difficult to achieve deep removal, resulting in unstable quality of regenerated powder and making it impossible to add it in large proportions; Second, after repeated use, the waste catalyst carrier is excessively sintered, the pore structure collapses, the specific surface area decreases significantly, and the catalytic activity is significantly reduced; Third, increasing the proportion of regenerated powder will seriously affect the plasticity and extrusion molding performance of the catalyst sludge, as well as the mechanical strength, wear resistance, and catalytic activity of the catalyst; Fourth, there is a lack of systematic research on the impact of regenerated powder quality, blending ratio, auxiliary materials, and preparation process parameters on catalyst performance, making it impossible to achieve large-scale industrial production. Summary of the Invention

[0005] The purpose of this invention is to provide a denitrification catalyst with a high ratio of regenerated support and its preparation method, which solves the problems of difficult deep removal of impurities, performance degradation caused by support sintering, deterioration of catalyst forming and use performance due to high ratio of regenerated powder in the resource utilization of existing waste SCR denitrification catalysts, and lack of complete supporting process research to support large-scale mass production.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A denitrification catalyst with a high proportion of regenerated carrier, comprising, by weight, 70-85 parts of high-quality regenerated titanium tungsten powder, 10-25 parts of virgin titanium dioxide, 1-5 parts of ammonium metavanadate, 1-4 parts of ammonium paratungstate, 2-6 parts of glass fiber, 0.5-2 parts of carboxymethyl cellulose, 0.1-0.5 parts of polyethylene oxide, 0.2-0.8 parts of stearic acid, 1-3 parts of citric acid, and 25-40 parts of deionized water.

[0007] Furthermore, by weight, it includes 75 parts of high-quality recycled titanium tungsten powder, 18 parts of virgin titanium dioxide, 3 parts of ammonium metavanadate, 2.5 parts of ammonium paratungstate, 4 parts of glass fiber, 1.2 parts of carboxymethyl cellulose, 0.3 parts of polyethylene oxide, 0.5 parts of stearic acid, 2 parts of citric acid, and 32 parts of deionized water.

[0008] Furthermore, by mass percentage, high-quality recycled titanium-tungsten powder comprises 80%~90% titanium oxide, 5%~10% tungsten oxide, 0.1%~0.5% vanadium oxide, ≤0.01% potassium, ≤0.01% sodium, <0.005% arsenic, ≤0.05% iron, ≤0.1% aluminum, and ≤0.2% silicon. By weight percentage, the glass fiber contains ≥55% silica and ≥15% alumina.

[0009] Furthermore, the microscopic specific surface area of ​​high-quality recycled titanium tungsten powder is >80m². 2 / g, with an average particle size of 2~5μm; The virgin titanium dioxide is anatase titanium dioxide with a purity ≥99.0% and a microscopic specific surface area of ​​80~100m². 2 / g, with an average particle size of 1~3μm; The glass fiber is alkali-free chopped glass fiber with a length of 3~6mm and a diameter of 9~13μm; The degree of substitution of carboxymethyl cellulose is 0.6~0.9, and the viscosity is 1000~3000 mPa. s; The molecular weight of polyethylene oxide is 2 million to 5 million.

[0010] A method for preparing a denitrification catalyst with a high doping ratio on a regenerated support, comprising: High-quality recycled titanium-tungsten powder was prepared using waste SCR denitrification catalyst; Ammonium metavanadate and ammonium paratungstate were added to deionized water, citric acid was added, and the mixture was heated and stirred to obtain an active component solution. High-quality recycled titanium tungsten powder, virgin titanium dioxide and glass fiber are dry-mixed evenly to obtain a dry mixture; Add the dry mixture to the active component solution, add the remaining deionized water in 3 to 5 portions during the stirring process, and then add carboxymethyl cellulose, polyethylene oxide and stearic acid to form catalyst slurry; After aging, the catalyst sludge is vacuum-kneaded and extruded into honeycomb-shaped catalyst blanks. The honeycomb catalyst preform is dried, calcined, and post-treated to obtain a denitrification catalyst with a high doping ratio on a regenerated support.

[0011] Furthermore, a method for preparing high-quality recycled titanium tungsten powder includes: The spent SCR denitrification catalyst module was disassembled to obtain spent catalyst blocks; The waste catalyst blocks are crushed to a particle size of less than 5 mm, then screened and pneumatically conveyed to remove ash, to obtain coarse powder of the waste catalyst. The spent catalyst coarse powder was made into a slurry with a solid content of 20%~30%, and was subjected to high-pressure sliding washing under the conditions of pressure of 10~20MPa and temperature of 40~60℃ for 30~60min. During the sliding washing process, fatty alcohol polyoxyethylene ether was added as a permeating agent, and the amount of permeating agent added was 0.1%~0.3% of the weight of spent catalyst coarse powder. After the sliding washing was completed, the first pressure filtration was performed to obtain the first filter cake and the first filtrate. The first filter cake is prepared into a slurry with a solid content of 15% to 25%, and then subjected to ultrasonic treatment at a frequency of 20 to 40 kHz and a power density of 0.5 to 1.0 W / cm³. 2 Ultrasonic chemical cleaning is performed at a temperature of 50~70℃ for 40~80 minutes. Disodium ethylenediaminetetraacetate is added as a complexing agent during the cleaning process. The amount of complexing agent added is 0.2%~0.5% of the weight of the first filter cake. After cleaning, a second pressure filtration is performed to obtain the second filter cake and the second filtrate. The second filter cake is made into a slurry with a solid content of 10%~20%. An alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate with a mass ratio of sodium hydroxide to sodium bicarbonate of 1:2~4. The amount of alkaline cleaning agent added is 1%~3% of the weight of the second filter cake. The reaction is carried out at a temperature of 60~80℃ and a stirring speed of 200~400r / min for 2~4h. After the reaction is completed, a third pressure filtration is performed to obtain the third filter cake and the third filtrate. After drying the third filter cake, it is pulverized to a particle size of less than 0.15 mm, and then electromagnetic iron removal is performed under a magnetic field strength of 10000~15000 Gauss for 10~20 min to obtain iron-removed powder. After iron removal, the powder is made into a slurry with a solid content of 20% to 30%. An organic complexing agent is added, which is a mixture of citric acid and oxalic acid with a mass ratio of 2 to 3:1. The amount of organic complexing agent added is 0.5% to 1.5% of the weight of the powder after iron removal. The mixture is activated for 1 to 3 hours at a temperature of 50 to 70°C and a stirring speed of 300 to 500 r / min. After activation, the mixture is filtered for the fourth time to obtain the fourth filter cake and the fourth filtrate. A sulfuric acid solution was added to the fourth filter cake to prepare a slurry with a solid content of 15%–25%. Acid leaching was then carried out at a temperature of 80–100℃ and a stirring speed of 400–600 r / min. The concentration of the sulfuric acid solution was 1–3 mol / L, and the leaching time was 3–6 h. Air was introduced during the leaching process at a flow rate of 0.5–1.0 m³ / min. 3 / (m 3 (min); After acid leaching, a fifth pressure filtration is performed to obtain the fifth filter cake and the fifth filtrate; The first and fifth filtrates were mixed, and an extractant was added for vanadium extraction. The extractant was a mixture of di(2-ethylhexyl)phosphoric acid and sulfonated kerosene, with a volume ratio of di(2-ethylhexyl)phosphoric acid to sulfonated kerosene of 1:3~5, an extraction ratio of 1:2~4, an extraction time of 10~20 min, and 3~5 extraction stages. After extraction, the vanadium-loaded organic phase was back-extracted with sodium hydroxide solution, with a concentration of 2~4 mol / L, a back-extraction ratio of 3~5:1, a back-extraction time of 15~30 min, and 2~3 back-extraction stages, to obtain a vanadium-containing back-extraction solution. The fifth filter cake is prepared into a slurry with a solid content of 20% to 30%. A titanium source and a tungsten source are added. The titanium source is titanium oxysulfate and the tungsten source is ammonium paratungstate. The amount of titanium source added is 5% to 10% of the weight of the fifth filter cake, and the amount of tungsten source added is 1% to 3% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 8 to 10 with ammonia water. The reaction is carried out at a temperature of 60 to 80°C and a stirring speed of 300 to 500 r / min for 2 to 4 hours. After the reaction is completed, a sixth pressure filtration is performed to obtain the sixth filter cake and the sixth filtrate. The sixth filter cake was flash-dried at an inlet temperature of 300-350℃ and an outlet temperature of 120-150℃ for 10-30 seconds. It was then pulverized to an average particle size of 2-5μm and subjected to gravity screening to obtain high-quality recycled titanium tungsten powder.

[0012] Furthermore, the heating and stirring temperature is 60~80℃, the stirring speed is 300~500r / min, and the stirring time is 30~60min.

[0013] Furthermore, the aging temperature is 20~30℃, the relative humidity is 60%~80%, and the aging time is 12~24h; The vacuum kneading process is repeated 2-3 times, with a vacuum level of (-0.08) to (-0.095) MPa. The extrusion molding pressure is 8~12MPa, and the extrusion speed is 0.5~1.0m / min.

[0014] Furthermore, the drying process of the honeycomb catalyst preform involves first microwave drying until the moisture content of the preform is 10%~15%, and then hot air drying until the moisture content of the preform is less than 1%. During the microwave drying process, the microwave frequency is 2450MHz, the power density is 0.5~1.0W / g, and the drying time is 2~4h. Hot air drying consists of three stages: the first stage has a temperature of 40~60℃, a relative humidity of 70%~80%, and a drying time of 6~12h; the second stage has a temperature of 60~80℃, a relative humidity of 50%~60%, and a drying time of 8~16h; and the third stage has a temperature of 80~100℃, a relative humidity of 30%~40%, and a drying time of 4~8h.

[0015] Furthermore, the calcination atmosphere is air, and the calcination process includes a heating stage, a low-temperature calcination stage, a high-temperature calcination stage, and a cooling stage. During the heating phase, the temperature is increased from room temperature to 200℃ at a rate of 1~2℃ / min, and then held for 1~2 hours. During the low-temperature calcination stage, the temperature is increased from 200℃ to 400℃ at a rate of 1~2℃ / min, and held for 2~4 hours. During the high-temperature calcination stage, the temperature is increased from 400℃ to 550-600℃ at a rate of 0.5-1℃ / min, and held for 4-8 hours. During the cooling stage, the temperature is reduced from the calcination temperature to 200℃ at a rate of 1~2℃ / min, and then naturally cooled to room temperature.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a denitrification catalyst with a high proportion of regenerated support, which is mainly composed of 70-85 parts of high-quality regenerated titanium-tungsten powder and 10-25 parts of virgin titanium dioxide, supplemented with vanadium, tungsten active precursors, inorganic reinforcing fibers, and various organic additives and solvents. This ensures the stability and uniform dispersion of the active materials and solves the problem of insufficient catalyst activity in catalysts prepared with high proportion of regenerated powder. High dosages of 70%–85% significantly consume the resource-based products of waste SCR catalysts, substantially reducing the amount of virgin titanium dioxide and tungsten vanadium raw materials used, thus lowering catalyst production costs. Simultaneously, it enables large-scale disposal of hazardous waste denitrification catalysts, achieving the recycling of heavy metals vanadium and tungsten, reducing heavy metal pollution of soil and water from hazardous waste landfills, thus balancing environmental protection and resource recycling value. Unlike traditional formulations where recycled powder content is less than 50% and increasing the dosage deteriorates molding and activity, this formulation uses virgin titanium dioxide to supplement the lack of specific surface area and pore structure in sintered recycled powder. Virgin anatase titanium dioxide has well-developed pores and sufficient active sites, compensating for the shortcomings of long-term sintering collapse and insufficient specific surface area of ​​the recycled powder carrier, ensuring overall catalytic denitrification activity. The independent addition of ammonium metavanadate and ammonium paratungstate allows for flexible control of the distribution of active sites on the catalyst surface. The recycled titanium tungsten powder inherently possesses trace amounts of vanadium and tungsten basic activity, and the added active precursors precisely compensate for the activity loss caused by insufficient activation of the recycled powder, ensuring denitrification efficiency meets standards even with high recycled powder dosages, broadening the catalyst's applicable flue gas temperature window, and improving its sulfur and water resistance stability. Glass fiber, as an inorganic reinforcing phase, improves the mechanical strength and wear resistance of the honeycomb preform after calcination, solving the problems of poor plasticity of recycled clay, easy cracking of extruded preforms, and easy pulverization and breakage of finished products. Carboxymethyl cellulose and polyethylene oxide compound act as plasticizers, lubricants, and binders, improving the rheological plasticity of the clay, reducing extrusion molding resistance, and adapting to the honeycomb large-pore thin-wall extrusion process. Stearic acid is an internal lubricant, reducing friction between the clay and the die and reducing surface defects of the preform. Citric acid has multiple functions of metal complexation, dispersion, and calcination aid. It can disperse powder to avoid agglomeration of titanium and tungsten powder, complex residual trace impurities of potassium, sodium, and arsenic to weaken the poisoning effect of impurities, and decompose at low temperature during calcination to create pores, repairing collapsed pores of recycled powder and increasing the specific surface area of ​​the carrier. Deionized water is used as a dispersion medium to precisely control the moisture content of the clay, ensuring stable and controllable clay preparation and extrusion processes. The components of this invention form a matched and compatible system within a certain weight range. If the content of a single additive is too high, it will easily cause calcined carbon residue and a decrease in strength. If the content is too low, the plasticity, strength, and activity improvement will fail. This ratio range can balance catalytic activity, molding and processing performance, and mechanical wear resistance. Under the premise of high blending of regenerated titanium tungsten powder, the prepared denitrification catalyst can still meet the activity and strength requirements of industrial applications, which has the basis for continuous industrial preparation and reduces the raw material cost of denitrification catalyst production.

[0017] Furthermore, the upper limits of impurities in high-quality recycled titanium-tungsten powder and the mineral composition of glass fiber are respectively limited to specifically address the problems of catalyst poisoning and shortened lifespan caused by excessive impurities in existing recycled powder. For recycled titanium-tungsten powder, the content of toxic and clogging impurities such as potassium, sodium, arsenic, iron, silicon, and aluminum is strictly limited to extremely low levels. Alkali metals potassium and sodium can cover the active sites of the catalyst, causing permanent deactivation. Arsenic is a typical poison for denitrification catalysts, and iron, aluminum, and silicon are prone to agglomeration and clogging of pores. Strict control of impurity thresholds can prevent the accumulation of impurities and poisoning of the catalyst after high doping with recycled powder, ensuring the long-term denitrification activity of the finished product. At the same time, the range of main components of titanium oxide and tungsten oxide is limited to ensure that the recycled powder has a basic carrier and active material skeleton, avoiding excessive removal of valuable metals. The minimum content of silica and alumina in glass fiber is limited to ensure that the glass fiber has high temperature resistance and high rigidity, does not soften or decompose during calcination, continues to play a reinforcing role in the skeleton, improves the overall mechanical stability of the catalyst, and prevents the honeycomb carrier from breaking under high temperature conditions.

[0018] Furthermore, by analyzing the specific surface area, particle size, length, molecular weight, and degree of substitution of recycled titanium tungsten powder, virgin titanium dioxide, glass fiber, and organic additives, microscopic parameters such as specific surface area, particle size, length, molecular weight, and degree of substitution are used to mitigate molding and activity defects caused by high levels of recycled powder at the raw material microscale. The specific surface area of ​​recycled titanium tungsten powder is >80 m². 2 g, particle size 2~5μm, ensuring that the regenerated powder restores its basic porosity and dispersibility after activation, and that the particle size range is suitable for uniform mixing of extruded slurry, without coarse particles causing defects such as pores in the green body; high purity virgin anatase titanium dioxide, 80~100 μm 2 / g specific surface area, utilizing the well-developed pores of virgin powder to compensate for the sintering collapse problem of recycled carrier, small-particle-size virgin powder fills the gaps between recycled powder particles, optimizing the overall pore structure; alkali-free short-cut glass fiber with limited length and diameter, the fiber length and thickness are moderate, which can be evenly dispersed in the clay to form a three-dimensional reinforcing network, without the fiber being too long and tangling or too short and losing its reinforcing effect; specific degree of substitution and viscosity of carboxymethyl cellulose and specific molecular weight of polyethylene oxide, precisely match the plasticizing and bonding requirements of clay. Too high viscosity will cause the clay to be too sticky and stick to the mold during extrusion, while too low viscosity will result in insufficient bonding and easy disintegration of the green body. Specific molecular weight range additives can achieve uniform and stable clay, greatly improving the qualified rate of extruded finished products.

[0019] This invention also provides a method for preparing a denitrification catalyst with a high proportion of recycled carrier. The method uses recycled titanium-tungsten powder to provide a qualified raw material basis for a 70%~85% high-component formulation. The active liquid is prepared by first dissolving the vanadium-tungsten precursor separately in citric acid and hot water to prepare an active component solution. Citric acid complexes vanadium-tungsten ions to prevent hydrolysis and agglomeration of metal ions, ensuring uniform dispersion of the active component. The recycled titanium-tungsten powder, virgin titanium dioxide, and glass fiber are first dry-mixed to ensure pre-dispersion of the inorganic solid powder. Then, water is added in stages, along with organic additives, and the mixture is further mixed. The staged water addition allows for precise control of the mud consistency, avoiding localized excessive thinning or dryness and powder agglomeration caused by a single water addition. The later addition of organic lubricating and binding agents reduces premature degradation of the additives, significantly improving the rheological plasticity of the mud and solving the problems of hard, poorly plastic, and high extrusion resistance in mud with high recycled powder content. The aging process of the clay material ensures thorough wetting of the powder and additives, uniform moisture diffusion, and releases internal stress. Multiple vacuum kneading processes remove internal air bubbles, preventing defects such as porosity, delamination, and cracking in the extruded green body, thus improving its density and uniformity. The mechanical strength of the finished product after calcination is significantly enhanced, making it suitable for the extrusion molding requirements of thin-walled honeycomb denitrification catalysts. Gradient drying combined with segmented temperature-controlled calcination slowly removes free water and water of crystallization from the green body at low temperatures, allowing organic additives to gradually decompose and be discharged without rapid gasification that could cause bubbling and cracking. Stepped temperature calcination precisely controls the carrier's crystal form and pore reconstruction, repairing collapsed pores from the sintering of recycled titanium-tungsten powder and optimizing the crystalline phase distribution of active components. The final product possesses high mechanical strength, high specific surface area, and excellent denitrification catalytic activity. This invention optimizes the catalyst formulation and preparation process parameters, enabling the industrial-scale production of high-quality catalysts with a recycled powder blending ratio of over 70%. By adding additives such as glass fiber, carboxymethyl cellulose, and polyethylene oxide, the plasticity and extrusion molding performance of the high-component recycled powder catalyst sludge are effectively improved, enhancing the catalyst's mechanical strength and wear resistance. Optimizing the drying and calcination process curves avoids problems such as cracking and deformation during drying and calcination, ensuring the catalyst's structural integrity and performance stability. A closed-loop process system is formed from the treatment of waste catalyst at the source to the production of finished catalyst, systematically solving the shortcomings of existing resource recovery processes, such as incomplete impurity removal, sintering deterioration of the recycled powder support, poor molding of high-component recycled powder, and inability to achieve large-scale industrial production. This system has significant value for large-scale industrial application. Furthermore, the high-component denitrification catalyst with recycled support prepared by this invention exhibits excellent catalytic activity, selectivity, mechanical strength, and wear resistance, meeting the requirements for industrial flue gas denitrification. Compared to denitrification catalysts prepared from 100% virgin powder, the production cost of the catalyst in this invention is significantly reduced, while simultaneously achieving full-scale, high-value recycling of waste SCR denitrification catalysts, reducing hazardous waste emissions.

[0020] Furthermore, the preparation of high-quality recycled titanium-tungsten powder involves a multi-step deep purification process, including mechanical ash removal, high-pressure sliding washing, ultrasonic chemical cleaning, alkaline arsenic removal, electromagnetic iron removal, pulping activation, and acid leaching. This effectively removes toxic and harmful impurities such as potassium, sodium, arsenic, iron, aluminum, and silicon from the spent catalyst, significantly improving the quality of the recycled powder. Simultaneously, the efficient acid leaching and crystallization reconstruction technology of titanium-tungsten can repair the pore structure of the spent catalyst support, increasing its specific surface area and catalytic activity. This solves the problem of excessive sintering and severe degradation of pore properties after multiple cycles of spent catalyst.

[0021] Furthermore, the heating and stirring parameters of the active component solution, including temperature, speed, and time, are standardized control conditions for the preparation process of the active solution. Heating at 60-80℃ increases the dissolution rate of ammonium metavanadate and ammonium paratungstate, and enhances the high-temperature complexing ability of citric acid, which can completely complex vanadium and tungsten ions to prevent hydrolysis and precipitation. Medium-speed stirring at 300-500 r / min balances dissolution uniformity and energy consumption, and stirring for 30-60 min ensures complete dissolution of the active components and stability of the complexation system. If the temperature is too low or the stirring is insufficient, the vanadium and tungsten precursors will not dissolve completely, the active components will not be evenly distributed during powder mixing, and the finished product will have localized lack of activity. The parameter range can stably produce a uniform and transparent active solution, ensuring uniform loading of active components after subsequent mixing with titanium and tungsten powder, and improving the overall denitrification efficiency consistency of the catalyst.

[0022] Furthermore, the pretreatment and extrusion process parameters for the green body solve the problems of easy cracking, low green body strength, and numerous molding defects in high-recycled clay powder. Room temperature and high humidity aging conditions allow the organic binder to fully impregnate the powder particles, slowly releasing the internal stress of the clay and significantly improving its plasticity. Two to three high-vacuum kneading processes thoroughly remove micro-air bubbles from the clay, ensuring complete bubble removal without excessive drying. The extrusion pressure and speed are matched to the rheological characteristics of the high-recycled clay powder; too low a pressure results in insufficient green body density and poor strength, while too high a pressure leads to high extrusion resistance and severe die wear. The extrusion speed range balances production efficiency and green body integrity, significantly reducing the rate of cracks, breaks, and deformation in honeycomb thin-walled green bodies, improving the yield of the molding process, and adapting to industrial continuous extrusion production lines.

[0023] Furthermore, the combined drying method of microwave drying followed by hot air drying ensures the uniformity of drying of the honeycomb-shaped green body, avoids cracking and deformation of the green body during the drying process, and improves the yield of finished products. The three-stage hot air drying gradually reduces humidity and increases temperature, slowly removing bound water and small molecule decomposition products of organic additives at low speed. The low temperature and high humidity stage prevents the surface of the green body from rapidly losing water and hardening. The medium temperature and medium humidity stage stabilizes dehydration, and the high temperature and low humidity stage thoroughly removes residual moisture, reducing the moisture content of the green body to below 1%. This avoids the rapid vaporization of moisture during the calcination stage, which could cause cracking and collapse of the honeycomb carrier, ensuring the integrity of the green body after drying and providing qualified semi-finished products for subsequent high-temperature calcination.

[0024] Furthermore, the segmented calcination heating, holding, and cooling rates and temperature ranges address the issues of irreversible sintering of the recycled carrier, agglomeration of active components, and residual carbon buildup in organic additives. A low-speed heating to 200℃ and holding at that temperature slowly removes residual moisture and low-molecular-weight organic additives from the green body. A slow heating to 400℃ in the medium-temperature stage fully decomposes all organic binders and lubricants, eliminating carbon residue that clogs the pores. A very slow heating to 550-600℃ in the high-temperature stage, followed by prolonged holding, controls the anatase crystal structure to prevent its transformation into non-catalytically active rutile, while simultaneously allowing the regenerated titanium-tungsten powder to reconstruct stable pores and uniformly crystallize and load the vanadium-tungsten active components onto the carrier surface, forming highly active catalytic sites. Stepped cooling prevents thermal stress fracture caused by sudden cooling of the high-temperature carrier. The final calcined product possesses a large specific surface area, well-developed pores, high mechanical strength, and excellent denitrification activity, compensating for the performance defects of the carrier caused by long-term sintering of waste catalysts.

[0025] Furthermore, the two ends of the formed catalyst are hardened by using a specific ratio of silica sol and aluminum sol as a hardener, controlling the impregnation time and drying parameters to improve the wear resistance of the catalyst ends and extend the catalyst's service life. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the preparation process of the denitrification catalyst with a high doping ratio on a regenerated support according to the present invention. Detailed Implementation

[0028] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0029] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0030] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0031] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0032] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0033] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0034] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings: This invention provides a denitrification catalyst with a high proportion of regenerated carrier, comprising, by weight, 70-85 parts of high-quality regenerated titanium tungsten powder, 10-25 parts of virgin titanium dioxide, 1-5 parts of ammonium metavanadate, 1-4 parts of ammonium paratungstate, 2-6 parts of glass fiber, 0.5-2 parts of carboxymethyl cellulose, 0.1-0.5 parts of polyethylene oxide, 0.2-0.8 parts of stearic acid, 1-3 parts of citric acid, and 25-40 parts of deionized water.

[0036] Preferably, by weight, it comprises 75 parts of high-quality recycled titanium tungsten powder, 18 parts of virgin titanium dioxide, 3 parts of ammonium metavanadate, 2.5 parts of ammonium paratungstate, 4 parts of glass fiber, 1.2 parts of carboxymethyl cellulose, 0.3 parts of polyethylene oxide, 0.5 parts of stearic acid, 2 parts of citric acid, and 32 parts of deionized water.

[0037] Preferably, by mass percentage, the high-quality recycled titanium-tungsten powder comprises 80%~90% titanium oxide, 5%~10% tungsten oxide, 0.1%~0.5% vanadium oxide, ≤0.01% potassium, ≤0.01% sodium, <0.005% arsenic, ≤0.05% iron, ≤0.1% aluminum, and ≤0.2% silicon, with a microscopic specific surface area >80m². 2 / g, with an average particle size of 2~5μm.

[0038] The virgin titanium dioxide is anatase titanium dioxide with a purity ≥99.0% and a microscopic specific surface area of ​​80~100m². 2 / g, with an average particle size of 1~3μm.

[0039] The glass fiber is alkali-free chopped glass fiber with a length of 3~6mm and a diameter of 9~13μm. By mass percentage, the glass fiber contains ≥55% silicon dioxide and ≥15% aluminum oxide.

[0040] The degree of substitution of carboxymethyl cellulose is 0.6~0.9, and the viscosity is 1000~3000 mPa. s.

[0041] The molecular weight of polyethylene oxide is 2 million to 5 million.

[0042] This invention also provides a method for preparing a denitrification catalyst with a high doping ratio on a regenerated support, specifically including the following steps: Step 1: Preparation of high-quality recycled titanium-tungsten powder (1) Mechanical ash removal: Disassemble the waste SCR denitrification catalyst module, remove the metal frame and sealing material to obtain waste catalyst block; crush the waste catalyst block into primary and secondary crushing in sequence until the particle size is less than 5mm, and then screen and pneumatic conveying mechanical ash removal to obtain waste catalyst coarse powder; (2) High-pressure slitting: The waste catalyst coarse powder is made into a slurry with a solid content of 20%~30%, and high-pressure slitting is carried out under the conditions of pressure of 10~20MPa and temperature of 40~60℃ for 30~60min. During the slitting process, fatty alcohol polyoxyethylene ether is added as a penetrant. The amount of penetrant added is 0.1%~0.3% of the weight of the waste catalyst coarse powder. After the slitting is completed, the first pressure filtration is carried out to obtain the first filter cake and the first filtrate. (3) Ultrasonic chemical cleaning: The first filter cake is made into a slurry with a solid content of 15%~25%, and ultrasonic cleaning is performed at an ultrasonic frequency of 20~40kHz and a power density of 0.5~1.0W / cm³. 2 Ultrasonic chemical cleaning is performed at a temperature of 50~70℃ for 40~80 minutes. Disodium ethylenediaminetetraacetate is added as a complexing agent during the cleaning process. The amount of complexing agent added is 0.2%~0.5% of the weight of the first filter cake. After cleaning, a second pressure filtration is performed to obtain the second filter cake and the second filtrate. (4) Alkaline arsenic removal: The second filter cake is made into a slurry with a solid content of 10%~20%, and an alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate. The mass ratio of sodium hydroxide to sodium bicarbonate is 1:2~4. The amount of alkaline cleaning agent added is 1%~3% of the weight of the second filter cake. The reaction is carried out at a temperature of 60~80℃ and a stirring speed of 200~400r / min for 2~4h. After the reaction is completed, a third pressure filtration is carried out to obtain the third filter cake and the third filtrate. (5) Electromagnetic iron removal: After drying the third filter cake, it is crushed to a particle size of less than 0.15 mm, and then electromagnetic iron removal is carried out under a magnetic field strength of 10000~15000 Gauss for 10~20 min to obtain iron-removed powder. (6) Pulping and activation: The iron-removed powder is made into a slurry with a solid content of 20%~30%, and an organic complexing agent is added. The organic complexing agent is a mixture of citric acid and oxalic acid, with a mass ratio of citric acid to oxalic acid of 2~3:1. The amount of organic complexing agent added is 0.5%~1.5% of the weight of the iron-removed powder. Activate for 1~3 hours at a temperature of 50~70℃ and a stirring speed of 300~500r / min. After activation, perform a fourth pressure filtration to obtain a fourth filter cake and a fourth filtrate. (7) Acid leaching for impurity removal: The fourth filter cake is made into a slurry with a solid content of 15%~25%, and acid leaching is carried out at a temperature of 80~100℃ and a stirring speed of 400~600r / min. The concentration of sulfuric acid solution is 1~3mol / L, and the acid leaching time is 3~6h. Air is introduced during the acid leaching process, and the air flow rate is 0.5~1.0m. 3 / (m 3 (min); After acid leaching, a fifth pressure filtration is performed to obtain the fifth filter cake and the fifth filtrate; (8) Vanadium-tungsten stepwise separation: The first and fifth filtrates are mixed, and an extractant is added to extract vanadium. The extractant is a mixture of di(2-ethylhexyl)phosphoric acid and sulfonated kerosene. The volume ratio of di(2-ethylhexyl)phosphoric acid to sulfonated kerosene is 1:3~5, the extraction ratio is 1:2~4, the extraction time is 10~20 min, and the number of extraction stages is 3~5. After extraction, the vanadium-loaded organic phase is back-extracted with sodium hydroxide solution. The concentration of sodium hydroxide solution is 2~4 mol / L, the back-extraction ratio is 3~5:1, the back-extraction time is 15~30 min, and the number of back-extraction stages is 2~3 to obtain vanadium-containing back-extraction solution. (9) Crystallization reconstruction: The fifth filter cake is made into a slurry with a solid content of 20%~30%. A titanium source and a tungsten source are added. The titanium source is titanium oxysulfate and the tungsten source is ammonium paratungstate. The amount of titanium source added is 5%~10% of the weight of the fifth filter cake and the amount of tungsten source added is 1%~3% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 8~10 with ammonia water. The reaction is carried out at a temperature of 60~80℃ and a stirring speed of 300~500r / min for 2~4h. After the reaction is completed, the sixth pressure filtration is carried out to obtain the sixth filter cake and the sixth filtrate. (10) Drying, pulverizing and gravity screening: The sixth filter cake is flash dried at an inlet temperature of 300~350℃ and an outlet temperature of 120~150℃ for 10~30s. It is then pulverized to an average particle size of 2~5μm and gravity screening is performed to obtain high-quality recycled titanium tungsten powder.

[0043] Step 2: Preparation of catalyst sludge (1) Preparation of active component solution: Ammonium metavanadate and ammonium paratungstate are added to deionized water, citric acid is added, and the mixture is stirred for 30 to 60 minutes at a temperature of 60 to 80℃ and a stirring speed of 300 to 500 r / min to obtain active component solution; (2) Dry mixing: High-quality recycled titanium tungsten powder, virgin titanium dioxide and glass fiber are dry mixed for 20-40 minutes to obtain dry mixture; (3) Wet mixing: Add the dry mixture to the active component solution and stir for 10-20 minutes. Then add the remaining deionized water in 3-5 portions, stirring for 5-10 minutes after each addition. Then add carboxymethyl cellulose, polyethylene oxide and stearic acid and continue stirring for 30-60 minutes to form catalyst slurry. (4) Aging: The catalyst mud is aged for 12-24 hours at a temperature of 20-30℃ and a relative humidity of 60%-80%.

[0044] Step 3: Extrusion molding of the catalyst The aged catalyst sludge was vacuum-kneaded 2-3 times, with the vacuum level controlled at -0.08 to -0.095 MPa. It was then extruded into a honeycomb catalyst preform, with an extrusion pressure controlled at 8-12 MPa and an extrusion speed controlled at 0.5-1.0 m / min. The resulting honeycomb catalyst preform had a pore count of 16×16-40×40 pores / square inch, a wall thickness of 0.8-1.2 mm, and a pitch of 3.5-4.5 mm.

[0045] Step 4: Drying the catalyst The honeycomb catalyst preform is first microwave-dried at a frequency of 2450 MHz and a power density of 0.5~1.0 W / g for 2~4 h, until the moisture content of the preform is 10%~15%. Then, it is hot-air dried until the moisture content is below 1%. The hot-air drying process consists of three stages: the first stage is at a temperature of 40~60℃ and a relative humidity of 70%~80% for 6~12 h; the second stage is at a temperature of 60~80℃ and a relative humidity of 50%~60% for 8~16 h; and the third stage is at a temperature of 80~100℃ and a relative humidity of 30%~40% for 4~8 h.

[0046] Step 5: Calcination of the catalyst The dried catalyst preform was calcined in an air atmosphere. The calcination process consisted of four stages: (1) Heating stage: Heating from room temperature to 200℃ at a heating rate of 1~2℃ / min and holding for 1~2h; (2) Low-temperature calcination stage: The temperature is increased from 200℃ to 400℃ at a rate of 1~2℃ / min, and held for 2~4 hours; (3) High-temperature calcination stage: The temperature is increased from 400℃ to 550-600℃ at a heating rate of 0.5-1℃ / min, and held for 4-8 hours; (4) Cooling stage: The calcination temperature is reduced to 200℃ at a cooling rate of 1~2℃ / min, and then naturally cooled to room temperature.

[0047] Step Six: Catalyst Post-processing and Packaging The calcined catalyst product is cut, polished, and tested to obtain a denitrification catalyst with a high doping ratio on a regenerated support.

[0048] The high-doping denitrification catalyst with qualified regenerated carrier is subjected to hardening treatment. Hardening agent is impregnated at both ends of the catalyst. The hardening agent is a mixture of silica sol and aluminum sol, with a mass ratio of silica sol to aluminum sol of 1~2:1. The impregnation time is 5~10 min. Then, it is dried at a temperature of 100~120℃ for 1~2 h to obtain a packageable product. The product is then classified, packaged, and stored in a warehouse.

[0049] The technical solution of the present invention will be further described in detail below through specific embodiments: Example 1: Step 1: Preparation of high-quality recycled titanium-tungsten powder: (1) Mechanical ash removal: The collected waste SCR denitrification catalyst modules with broken mechanical structure and sintering that do not meet the conditions for regeneration are disassembled, and the metal frame and sealing material are removed to obtain waste catalyst blocks; the waste catalyst blocks are sent to a jaw crusher for primary crushing to crush to a particle size of less than 50 mm, and then sent to a hammer crusher for secondary crushing to crush to a particle size of less than 5 mm; the crushed waste catalyst particles are sent to a vibrating screen for screening, the material on the screen is returned to the hammer crusher for further crushing, and the material under the screen is sent to a pneumatic conveying system for pneumatic conveying and mechanical ash removal by compressed air to remove loose dust and agglomerated impurities on the surface of the catalyst particles and collect waste catalyst coarse powder.

[0050] (2) High-pressure slitting: The waste catalyst coarse powder is fed into the high-pressure slitting device, and deionized water is added to make a slurry with a solid content of 25%. High-pressure slitting is carried out under the conditions of pressure of 15MPa and temperature of 50℃ for 45min. During the slitting process, fatty alcohol polyoxyethylene ether is added as a permeating agent. The amount of fatty alcohol polyoxyethylene ether added is 0.2% of the weight of the waste catalyst coarse powder. After the slitting is completed, the slurry is sent to the plate and frame filter press for the first filtration to obtain the first filter cake and the first filtrate. The first filtrate contains soluble impurities such as vanadium, potassium and sodium, and is sent to the subsequent vanadium-tungsten cascade separation process.

[0051] (3) Ultrasonic chemical cleaning: The first filter cake is sent into an ultrasonic cleaning tank, and deionized water is added to make a slurry with a solid content of 20%. The ultrasonic cleaning is carried out at an ultrasonic frequency of 30kHz and a power density of 0.75W / cm³. 2 Ultrasonic chemical cleaning was performed at a temperature of 60℃ for 60 minutes. During the cleaning process, disodium ethylenediaminetetraacetate (EDTA-2Na) was added as a complexing agent. The amount of disodium ethylenediaminetetraacetate added was 0.35% of the weight of the first filter cake. After ultrasonic chemical cleaning, the slurry was sent to a plate and frame filter press for a second filtration to obtain a second filter cake and a second filtrate. The second filtrate contained soluble iron, arsenic and other impurities, and was sent to the wastewater treatment system.

[0052] (4) Alkaline arsenic removal: The second filter cake is fed into the reactor, and deionized water is added to make a slurry with a solid content of 15%. After stirring evenly, an alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate. The mass ratio of sodium hydroxide to sodium bicarbonate is 1:3. The amount of alkaline cleaning agent added is 2% of the weight of the second filter cake. The reaction is carried out at a temperature of 70℃ and a stirring speed of 300r / min for 3 hours. After the reaction is completed, the slurry is sent to a plate and frame filter press for a third filtration to obtain the third filter cake and the third filtrate. The third filtrate contains impurities such as arsenate and is sent to the wastewater treatment system.

[0053] (5) Electromagnetic iron removal: The third filter cake is sent to the drying oven and dried at 110℃ for 18 hours. Then it is sent to the pulverizer for pulverization until the particle size is less than 0.15mm. The pulverized powder is sent to the electromagnetic iron remover for electromagnetic iron removal. The magnetic field strength of the electromagnetic iron remover is 12500 Gauss and the iron removal time is 15min. Solid magnetic iron impurities are removed to obtain the iron-removed powder.

[0054] (6) Pulping and activation: The iron-removed powder is sent to the activation tank, and deionized water is added to make a slurry with a solid content of 25%. After stirring evenly, an organic complexing agent is added. The organic complexing agent is a mixture of citric acid and oxalic acid. The mass ratio of citric acid to oxalic acid is 2.5:1. The amount of organic complexing agent added is 1.0% of the weight of the iron-removed powder. The slurry is activated for 2 hours at a temperature of 60℃ and a stirring speed of 400r / min to remove soluble iron and aluminum impurities. After activation, the slurry is sent to a plate and frame filter press for the fourth filter press to obtain the fourth filter cake and the fourth filtrate. The fourth filtrate is sent to the wastewater treatment system.

[0055] (7) Acid leaching for impurity removal: The fourth filter cake is fed into the acid leaching reactor, and sulfuric acid solution is added to prepare a slurry with a solid content of 20% and a sulfuric acid solution concentration of 2 mol / L; acid leaching is carried out at a temperature of 90℃ and a stirring speed of 500 r / min for 4.5 h; air is introduced during the acid leaching process at a flow rate of 0.75 m³ / min. 3 / (m 3 (min) to promote the oxidation and dissolution of impurities; after acid leaching, the slurry is sent to a plate and frame filter press for the fifth filtration to obtain the fifth filter cake and the fifth filtrate. The fifth filtrate contains valuable metals such as vanadium and tungsten, which are sent to the subsequent vanadium-tungsten cascade separation process.

[0056] (8) Vanadium-tungsten cascade separation: The first and fifth filtrates are mixed and sent to the extraction tank. Vanadium is extracted by adding an extractant, which is a mixture of di(2-ethylhexyl)phosphoric acid (P204) and sulfonated kerosene. The volume ratio of P204 to sulfonated kerosene is 1:4, the extraction ratio (O / A) is 1:3, the extraction time is 15 min, and the number of extraction stages is 4. After extraction, the vanadium-loaded organic phase is sent to the back-extraction tank. Sodium hydroxide solution is added for back-extraction. The concentration of sodium hydroxide solution is 3 mol / L, the back-extraction ratio (O / A) is 4:1, the back-extraction time is 22 min, and the number of back-extraction stages is 2. Vanadium-containing back-extraction liquid is obtained and used to prepare vanadium products. The raffinate mainly contains tungsten and is sent to the tungsten recovery process. Tungsten products are obtained by evaporation, concentration, and crystallization.

[0057] (9) Crystallization reconstruction: The fifth filter cake is fed into a pulping tank, and deionized water is added to make a slurry with a solid content of 25%. After stirring evenly, titanium source and tungsten source are added. The titanium source is titanium oxysulfate, and the tungsten source is ammonium paratungstate. The amount of titanium source added is 7.5% of the weight of the fifth filter cake, and the amount of tungsten source added is 2% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 9 with ammonia water. The reaction is carried out for 3 hours at a temperature of 70℃ and a stirring speed of 400r / min to carry out the crystallization reconstruction of the titanium-tungsten carrier. After the reaction is completed, the slurry is sent to a plate and frame filter press for the sixth filtration to obtain the sixth filter cake and the sixth filtrate. The sixth filtrate is sent to the wastewater treatment system.

[0058] (10) Drying, pulverizing and gravity screening: The sixth filter cake is sent to a flash dryer for drying. The inlet temperature is 325℃, the outlet temperature is 135℃, and the drying time is 20s. The dried powder is sent to an air jet mill for pulverizing until the average particle size is 3.5μm. Then it is sent to a gravity screen for gravity screening to remove impurities with high density such as silicon and aluminum, and obtain high-quality recycled titanium tungsten powder.

[0059] Step 2: Preparation of denitration catalyst with high doping ratio on regenerated support: Weigh out 75 parts by weight of high-quality recycled titanium tungsten powder, 18 parts of virgin titanium dioxide, 3 parts of ammonium metavanadate, 2.5 parts of ammonium paratungstate, 4 parts of glass fiber, 1.2 parts of carboxymethyl cellulose, 0.3 parts of polyethylene oxide, 0.5 parts of stearic acid, 2 parts of citric acid, and 32 parts of deionized water.

[0060] (1) Preparation of active component solution: 3 parts ammonium metavanadate and 2.5 parts ammonium paratungstate were added to 10 parts deionized water, stirred evenly, and then 2 parts citric acid were added. The mixture was stirred for 45 minutes at a temperature of 70℃ and a stirring speed of 400r / min until it was completely dissolved to obtain the active component solution.

[0061] (2) Dry mixing: 75 parts of high-quality recycled titanium tungsten powder, 18 parts of virgin titanium dioxide and 4 parts of glass fiber are fed into a double helix cone mixer for dry mixing. The dry mixing time is 30 minutes. After uniform mixing, the dry mixture is obtained.

[0062] (3) Wet mixing: The dry mixture is fed into a kneader, the active component solution is added, and the mixture is stirred for 15 minutes; then the remaining 22 parts of deionized water are added in 4 batches, and the mixture is stirred for 7 minutes after each addition; then 1.2 parts of carboxymethyl cellulose, 0.3 parts of polyethylene oxide and 0.5 parts of stearic acid are added, and the mixture is stirred for 45 minutes until a uniform catalyst sludge with good plasticity is formed; the moisture content of the sludge is 30%.

[0063] (4) Aging: Take the catalyst mud out of the kneader and put it into a sealed container. Aging is carried out for 18 hours at a temperature of 25℃ and a relative humidity of 70% to make the moisture and additives in the mud evenly distributed and improve the plasticity and molding performance of the mud.

[0064] (5) Extrusion molding: The aged catalyst sludge is fed into a vacuum sludge mill for sludge ...

[0065] (6) Drying: The extruded honeycomb catalyst preform is sent to a microwave drying chamber for microwave drying. The microwave frequency is 2450MHz, the power density is 0.75W / g, and the drying time is 3h, until the moisture content of the preform is 12%. Then it is sent to a hot air drying chamber for hot air drying. The hot air drying is divided into three stages: the first stage temperature is 50℃, the relative humidity is 75%, and the drying time is 9h; the second stage temperature is 70℃, the relative humidity is 55%, and the drying time is 12h; the third stage temperature is 90℃, the relative humidity is 35%, and the drying time is 6h. The hot air drying is carried out until the moisture content of the preform is 0.8%.

[0066] (7) Calcination: The dried catalyst blank is sent into a tunnel kiln for calcination. The calcination atmosphere is air. The calcination process is divided into four stages: Heating stage: The temperature is increased from room temperature to 200℃ at a rate of 1.5℃ / min and held for 1.5h to remove residual moisture and volatile components from the green body; Low-temperature calcination stage: The temperature is increased from 200℃ to 400℃ at a rate of 1.5℃ / min and held for 3 hours to decompose organic additives such as carboxymethyl cellulose and polyethylene oxide. High-temperature calcination stage: The temperature is increased from 400℃ to 575℃ at a rate of 0.75℃ / min and held for 6 hours to allow the active components to fully combine with the support and form stable catalytic active centers. Cooling stage: The temperature is reduced from the calcination temperature to 200℃ at a cooling rate of 1.5℃ / min, and then naturally cooled to room temperature to obtain the denitrification catalyst product with a high regenerated support ratio.

[0067] (8) Post-processing and packaging: The calcined catalyst product is cut and polished to remove burrs and edges, and then subjected to appearance inspection and size measurement to obtain a denitrification catalyst with a high regenerated support ratio. The qualified catalyst products are subjected to hardening end treatment, in which a hardening agent is impregnated at both ends of the catalyst. The hardening agent is a mixture of silica sol and alumina sol, with a mass ratio of silica sol to alumina sol of 1.5:1 and an impregnation time of 7 min. Then, it is dried at a temperature of 110℃ for 1.5 h to obtain the packaged denitrification catalyst product. The packaged products are classified and packaged according to specifications and stored in the warehouse.

[0068] Testing revealed that the high-quality recycled titanium-tungsten powder prepared in Example 1 contained, by mass percentage, 85.2% titanium oxide, 7.8% tungsten oxide, 0.3% vanadium oxide, 0.008% potassium, 0.007% sodium, 0.004% arsenic, 0.04% iron, 0.08% aluminum, and 0.15% silicon, with a specific surface area of ​​88 m². 2 / g, with an average particle size of 3.2μm.

[0069] Example 2: Step 1: Preparation of high-quality recycled titanium-tungsten powder: (1) Mechanical ash removal: The collected waste SCR denitrification catalyst modules with broken mechanical structure and sintering that do not meet the conditions for regeneration are disassembled, and the metal frame and sealing material are removed to obtain waste catalyst blocks; the waste catalyst blocks are sent to a jaw crusher for primary crushing to crush to a particle size of less than 50 mm, and then sent to a hammer crusher for secondary crushing to crush to a particle size of less than 5 mm; the crushed waste catalyst particles are sent to a vibrating screen for screening, the material on the screen is returned to the hammer crusher for further crushing, and the material under the screen is sent to a pneumatic conveying system for pneumatic conveying and mechanical ash removal by compressed air to remove loose dust and agglomerated impurities on the surface of the catalyst particles and collect waste catalyst coarse powder.

[0070] (2) High-pressure slitting: The waste catalyst coarse powder is sent to the high-pressure slitting device, and deionized water is added to make a slurry with a solid content of 22%. High-pressure slitting is carried out under the conditions of pressure of 12MPa and temperature of 45℃ for 50min. During the slitting process, fatty alcohol polyoxyethylene ether is added as a permeating agent. The amount of fatty alcohol polyoxyethylene ether added is 0.15% of the weight of the waste catalyst coarse powder. After the slitting is completed, the slurry is sent to the plate and frame filter press for the first filtration to obtain the first filter cake and the first filtrate. The first filtrate contains soluble impurities such as vanadium, potassium and sodium, and is sent to the subsequent vanadium-tungsten cascade separation process.

[0071] (3) Ultrasonic chemical cleaning: The first filter cake is sent into an ultrasonic cleaning tank, and deionized water is added to make a slurry with a solid content of 18%. The ultrasonic cleaning is carried out at an ultrasonic frequency of 25kHz and a power density of 0.6W / cm³. 2 Ultrasonic chemical cleaning was performed at a temperature of 55℃ for 70 minutes. During the cleaning process, disodium ethylenediaminetetraacetate (EDTA-2Na) was added as a complexing agent. The amount of disodium ethylenediaminetetraacetate added was 0.3% of the weight of the first filter cake. After ultrasonic chemical cleaning, the slurry was sent to a plate and frame filter press for a second filtration to obtain a second filter cake and a second filtrate. The second filtrate contained soluble iron, arsenic and other impurities, and was sent to the wastewater treatment system.

[0072] (4) Alkaline arsenic removal: The second filter cake is fed into the reactor, and deionized water is added to make a slurry with a solid content of 12%. After stirring evenly, an alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate. The mass ratio of sodium hydroxide to sodium bicarbonate is 1:2.5. The amount of alkaline cleaning agent added is 1.5% of the weight of the second filter cake. The reaction is carried out at a temperature of 65℃ and a stirring speed of 250r / min for 3.5h. After the reaction is completed, the slurry is sent to a plate and frame filter press for a third filtration to obtain the third filter cake and the third filtrate. The third filtrate contains impurities such as arsenate and is sent to the wastewater treatment system.

[0073] (5) Electromagnetic iron removal: The third filter cake is sent to the drying oven and dried at 105℃ for 20h. Then it is sent to the pulverizer for pulverization until the particle size is less than 0.15mm. The pulverized powder is sent to the electromagnetic iron remover for electromagnetic iron removal. The magnetic field strength of the electromagnetic iron remover is 11000 Gauss and the iron removal time is 18min. Solid magnetic iron impurities are removed to obtain iron-removed powder.

[0074] (6) Pulping and activation: The iron-removed powder is sent to the activation tank, and deionized water is added to make a slurry with a solid content of 22%. After stirring evenly, an organic complexing agent is added. The organic complexing agent is a mixture of citric acid and oxalic acid, with a mass ratio of citric acid to oxalic acid of 2:1. The amount of organic complexing agent added is 0.8% of the weight of the iron-removed powder. The slurry is activated for 2.5 hours at a temperature of 55℃ and a stirring speed of 350r / min to remove soluble iron and aluminum impurities. After activation, the slurry is sent to a plate and frame filter press for the fourth filtration to obtain the fourth filter cake and the fourth filtrate. The fourth filtrate is sent to the wastewater treatment system.

[0075] (7) Acid leaching for impurity removal: The fourth filter cake is fed into an acid leaching reactor, and sulfuric acid solution is added to prepare a slurry with a solid content of 18% and a sulfuric acid solution concentration of 1.5 mol / L; acid leaching is carried out at a temperature of 85℃ and a stirring speed of 450 r / min for 5 hours; air is introduced during the acid leaching process at a flow rate of 0.6 m³ / min. 3 / (m 3 (min) to promote the oxidation and dissolution of impurities; after acid leaching, the slurry is sent to a plate and frame filter press for the fifth filtration to obtain the fifth filter cake and the fifth filtrate. The fifth filtrate contains valuable metals such as vanadium and tungsten, which are sent to the subsequent vanadium-tungsten cascade separation process.

[0076] (8) Vanadium-tungsten cascade separation: The first and fifth filtrates are mixed and sent to the extraction tank. Vanadium is extracted by adding an extractant, which is a mixture of di(2-ethylhexyl)phosphoric acid (P204) and sulfonated kerosene. The volume ratio of P204 to sulfonated kerosene is 1:3.5, the extraction ratio (O / A) is 1:2.5, the extraction time is 18 min, and the number of extraction stages is 3. After extraction, the vanadium-loaded organic phase is sent to the back-extraction tank. Sodium hydroxide solution is added for back-extraction. The concentration of sodium hydroxide solution is 2.5 mol / L, the back-extraction ratio (O / A) is 3.5:1, the back-extraction time is 25 min, and the number of back-extraction stages is 3. The vanadium-containing back-extraction solution is obtained and used to prepare vanadium products. The raffinate mainly contains tungsten and is sent to the tungsten recovery process. Tungsten products are obtained by evaporation, concentration, and crystallization.

[0077] (9) Crystallization reconstruction: The fifth filter cake is fed into a pulping tank, and deionized water is added to make a slurry with a solid content of 22%. After stirring evenly, titanium source and tungsten source are added. The titanium source is titanium oxysulfate, and the tungsten source is ammonium paratungstate. The amount of titanium source added is 6% of the weight of the fifth filter cake, and the amount of tungsten source added is 1.5% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 8.5 with ammonia water. The reaction is carried out for 3.5 hours at a temperature of 65℃ and a stirring speed of 350r / min to carry out the crystallization reconstruction of the titanium-tungsten carrier. After the reaction is completed, the slurry is sent to a plate and frame filter press for the sixth filtration to obtain the sixth filter cake and the sixth filtrate. The sixth filtrate is sent to the wastewater treatment system.

[0078] (10) Drying, pulverizing and gravity screening: The sixth filter cake is sent to a flash dryer for drying. The inlet temperature is 310℃, the outlet temperature is 125℃, and the drying time is 25s. The dried powder is sent to an air jet mill for pulverizing until the average particle size is 3μm. Then it is sent to a gravity screen for gravity screening to remove impurities with high density such as silicon and aluminum, and obtain high-quality recycled titanium tungsten powder.

[0079] Step 2: Preparation of denitration catalyst with high doping ratio on regenerated support: Weigh out 80 parts by weight of high-quality recycled titanium tungsten powder, 13 parts of virgin titanium dioxide, 2.5 parts of ammonium metavanadate, 2 parts of ammonium paratungstate, 3.5 parts of glass fiber, 1 part of carboxymethyl cellulose, 0.25 parts of polyethylene oxide, 0.4 parts of stearic acid, 1.8 parts of citric acid, and 30 parts of deionized water.

[0080] (1) Preparation of active component solution: 2.5 parts of ammonium metavanadate and 2 parts of ammonium paratungstate were added to 9 parts of deionized water, stirred evenly, and then 1.8 parts of citric acid were added. The mixture was stirred for 50 minutes at a temperature of 65℃ and a stirring speed of 350r / min until it was completely dissolved to obtain the active component solution.

[0081] (2) Dry mixing: 80 parts of high-quality recycled titanium tungsten powder, 13 parts of virgin titanium dioxide and 3.5 parts of glass fiber are fed into a double spiral conical mixer for dry mixing. The dry mixing time is 25 minutes. After uniform mixing, the dry mixture is obtained.

[0082] (3) Wet mixing: The dry mixture is fed into a kneader, the active component solution is added, and the mixture is stirred for 12 minutes; then the remaining 21 parts of deionized water are added in 3 batches, and the mixture is stirred for 8 minutes after each addition; then 1 part of carboxymethyl cellulose, 0.25 parts of polyethylene oxide and 0.4 parts of stearic acid are added, and the mixture is stirred for 50 minutes until a uniform catalyst sludge with good plasticity is formed; the moisture content of the sludge is 29%.

[0083] (4) Aging: Take the catalyst mud out of the kneader and put it into a sealed container. Aging is carried out for 20 hours at a temperature of 22℃ and a relative humidity of 65% to make the moisture and additives in the mud evenly distributed and improve the plasticity and molding performance of the mud.

[0084] (5) Extrusion molding: The aged catalyst sludge is fed into a vacuum sludge mill for sludge ...

[0085] (6) Drying: The extruded honeycomb catalyst preform is sent to a microwave drying chamber for microwave drying. The microwave frequency is 2450MHz, the power density is 0.6W / g, and the drying time is 3.5h, until the moisture content of the preform is 13%. Then it is sent to a hot air drying chamber for hot air drying. The hot air drying is divided into three stages: the first stage temperature is 45℃, the relative humidity is 72%, and the drying time is 10h; the second stage temperature is 65℃, the relative humidity is 52%, and the drying time is 14h; the third stage temperature is 85℃, the relative humidity is 32%, and the drying time is 7h. The hot air drying is carried out until the moisture content of the preform is 0.7%.

[0086] (7) Calcination: The dried catalyst blank is sent into a tunnel kiln for calcination. The calcination atmosphere is air. The calcination process is divided into four stages: Heating stage: The temperature is increased from room temperature to 200℃ at a rate of 1.2℃ / min and held for 1.8h to remove residual moisture and volatile components from the green body; Low-temperature calcination stage: The temperature is increased from 200℃ to 400℃ at a rate of 1.2℃ / min and held for 3.5h to decompose organic additives such as carboxymethyl cellulose and polyethylene oxide; High-temperature calcination stage: The temperature is increased from 400℃ to 560℃ at a rate of 0.6℃ / min and held for 7 hours to allow the active components to fully combine with the support and form stable catalytic active centers. Cooling stage: The temperature is reduced from the calcination temperature to 200℃ at a cooling rate of 1.2℃ / min, and then naturally cooled to room temperature to obtain the denitrification catalyst product with a high regenerated support ratio.

[0087] (8) Post-processing and packaging: The calcined catalyst product is cut and polished to remove burrs and edges, and then subjected to appearance inspection and size measurement to obtain a denitrification catalyst with a high regenerated carrier ratio. The qualified catalyst products are subjected to hardening end treatment, in which a hardening agent is impregnated at both ends of the catalyst. The hardening agent is a mixture of silica sol and alumina sol, with a mass ratio of silica sol to alumina sol of 1.2:1 and an impregnation time of 8 min. Then, it is dried at a temperature of 105℃ for 1.8 h to obtain the packaged denitrification catalyst product. The packaged products are classified and packaged according to specifications and stored in the warehouse.

[0088] Testing revealed that the high-quality recycled titanium-tungsten powder prepared in Example 2 contained, by mass percentage, 86.5% titanium oxide, 7.2% tungsten oxide, 0.25% vanadium oxide, 0.007% potassium, 0.006% sodium, 0.003% arsenic, 0.035% iron, 0.07% aluminum, and 0.12% silicon, with a specific surface area of ​​92 m². 2 / g, with an average particle size of 2.8μm.

[0089] Example 3: Step 1: Preparation of high-quality recycled titanium-tungsten powder: (1) Mechanical ash removal: The collected waste SCR denitrification catalyst modules with broken mechanical structure and sintering that do not meet the conditions for regeneration are disassembled, and the metal frame and sealing material are removed to obtain waste catalyst blocks; the waste catalyst blocks are sent to a jaw crusher for primary crushing to crush to a particle size of less than 50 mm, and then sent to a hammer crusher for secondary crushing to crush to a particle size of less than 5 mm; the crushed waste catalyst particles are sent to a vibrating screen for screening, the material on the screen is returned to the hammer crusher for further crushing, and the material under the screen is sent to a pneumatic conveying system for pneumatic conveying and mechanical ash removal by compressed air to remove loose dust and agglomerated impurities on the surface of the catalyst particles and collect waste catalyst coarse powder.

[0090] (2) High-pressure slitting: The waste catalyst coarse powder is sent to the high-pressure slitting device, and deionized water is added to make a slurry with a solid content of 20%. High-pressure slitting is carried out under the conditions of pressure of 10MPa and temperature of 60℃ for 30min. During the slitting process, fatty alcohol polyoxyethylene ether is added as a permeating agent. The amount of fatty alcohol polyoxyethylene ether added is 0.1% of the weight of the waste catalyst coarse powder. After the slitting is completed, the slurry is sent to the plate and frame filter press for the first filtration to obtain the first filter cake and the first filtrate. The first filtrate contains soluble impurities such as vanadium, potassium and sodium, and is sent to the subsequent vanadium-tungsten cascade separation process.

[0091] (3) Ultrasonic chemical cleaning: The first filter cake is sent into an ultrasonic cleaning tank, and deionized water is added to make a slurry with a solid content of 15%. The ultrasonic cleaning is carried out at an ultrasonic frequency of 40kHz and a power density of 0.5W / cm³. 2 Ultrasonic chemical cleaning was performed at a temperature of 70℃ for 40 minutes. During the cleaning process, disodium ethylenediaminetetraacetate (EDTA-2Na) was added as a complexing agent. The amount of disodium ethylenediaminetetraacetate added was 0.5% of the weight of the first filter cake. After ultrasonic chemical cleaning, the slurry was sent to a plate and frame filter press for a second filtration to obtain a second filter cake and a second filtrate. The second filtrate contained soluble impurities such as iron and arsenic and was sent to the wastewater treatment system.

[0092] (4) Alkaline arsenic removal: The second filter cake is fed into the reactor, and deionized water is added to make a slurry with a solid content of 10%. After stirring evenly, an alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate. The mass ratio of sodium hydroxide to sodium bicarbonate is 1:4. The amount of alkaline cleaning agent added is 3% of the weight of the second filter cake. The reaction is carried out at a temperature of 60℃ and a stirring speed of 200r / min for 4 hours. After the reaction is completed, the slurry is sent to a plate and frame filter press for a third filtration to obtain the third filter cake and the third filtrate. The third filtrate contains impurities such as arsenate and is sent to the wastewater treatment system.

[0093] (5) Electromagnetic iron removal: The third filter cake is sent to the drying oven and dried at 105℃ for 20h. Then it is sent to the pulverizer for pulverization until the particle size is less than 0.15mm. The pulverized powder is sent to the electromagnetic iron remover for electromagnetic iron removal. The magnetic field strength of the electromagnetic iron remover is 15000 Gauss and the iron removal time is 10min. Solid magnetic iron impurities are removed to obtain iron-removed powder.

[0094] (6) Pulping and activation: The iron-removed powder is sent to the activation tank, and deionized water is added to make a slurry with a solid content of 20%. After stirring evenly, an organic complexing agent is added. The organic complexing agent is a mixture of citric acid and oxalic acid. The mass ratio of citric acid to oxalic acid is 2.5:1. The amount of organic complexing agent added is 0.5% of the weight of the iron-removed powder. The slurry is activated for 1 hour at a temperature of 50℃ and a stirring speed of 500r / min to remove soluble iron and aluminum impurities. After activation, the slurry is sent to a plate and frame filter press for the fourth filter press to obtain the fourth filter cake and the fourth filtrate. The fourth filtrate is sent to the wastewater treatment system.

[0095] (7) Acid leaching for impurity removal: The fourth filter cake is fed into the acid leaching reactor, and sulfuric acid solution is added to prepare a slurry with a solid content of 25% and a sulfuric acid solution concentration of 1 mol / L; acid leaching is carried out at a temperature of 80℃ and a stirring speed of 600 r / min for 3 hours; air is introduced during the acid leaching process at a flow rate of 1.0 m³ / min. 3 / (m 3 (min) to promote the oxidation and dissolution of impurities; after acid leaching, the slurry is sent to a plate and frame filter press for the fifth filtration to obtain the fifth filter cake and the fifth filtrate. The fifth filtrate contains valuable metals such as vanadium and tungsten, which are sent to the subsequent vanadium-tungsten cascade separation process.

[0096] (8) Vanadium-tungsten cascade separation: The first and fifth filtrates are mixed and sent to the extraction tank. Vanadium is extracted by adding an extractant, which is a mixture of di(2-ethylhexyl)phosphoric acid (P204) and sulfonated kerosene. The volume ratio of P204 to sulfonated kerosene is 1:3, the extraction ratio (O / A) is 1:2, the extraction time is 10 min, and the number of extraction stages is 4. After extraction, the vanadium-loaded organic phase is sent to the back-extraction tank. Sodium hydroxide solution is added for back-extraction. The concentration of sodium hydroxide solution is 2 mol / L, the back-extraction ratio (O / A) is 3:1, the back-extraction time is 30 min, and the number of back-extraction stages is 2. Vanadium-containing back-extraction liquid is obtained and used to prepare vanadium products. The raffinate mainly contains tungsten and is sent to the tungsten recovery process. Tungsten products are obtained by evaporation, concentration, and crystallization.

[0097] (9) Crystallization reconstruction: The fifth filter cake is fed into a pulping tank, and deionized water is added to make a slurry with a solid content of 30%. After stirring evenly, titanium source and tungsten source are added. The titanium source is titanium oxysulfate, and the tungsten source is ammonium paratungstate. The amount of titanium source added is 5% of the weight of the fifth filter cake, and the amount of tungsten source added is 3% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 8 with ammonia water. The reaction is carried out for 2 hours at a temperature of 60℃ and a stirring speed of 500r / min to carry out the crystallization reconstruction of the titanium-tungsten carrier. After the reaction is completed, the slurry is sent to a plate and frame filter press for the sixth filtration to obtain the sixth filter cake and the sixth filtrate. The sixth filtrate is sent to the wastewater treatment system.

[0098] (10) Drying, pulverizing and gravity screening: The sixth filter cake is sent to a flash dryer for drying. The inlet temperature is 300℃, the outlet temperature is 120℃, and the drying time is 30s. The dried powder is sent to an air jet mill for pulverizing until the average particle size is 2μm. Then it is sent to a gravity screen for gravity screening to remove impurities with high density such as silicon and aluminum, and obtain high-quality recycled titanium tungsten powder.

[0099] Step 2: Preparation of denitration catalyst with high doping ratio on regenerated support: Weigh out 70 parts by weight of high-quality recycled titanium tungsten powder, 25 parts of virgin titanium dioxide, 5 parts of ammonium metavanadate, 1 part of ammonium paratungstate, 2 parts of glass fiber, 0.5 parts of carboxymethyl cellulose, 0.5 parts of polyethylene oxide, 0.8 parts of stearic acid, 1 part of citric acid, and 25 parts of deionized water.

[0100] (1) Preparation of active component solution: 5 parts ammonium metavanadate and 1 part ammonium paratungstate were added to 7 parts deionized water, stirred evenly, and then 1 part citric acid was added; the mixture was stirred for 60 min at a temperature of 60℃ and a stirring speed of 300 r / min until it was completely dissolved to obtain active component solution.

[0101] (2) Dry mixing: 70 parts of high-quality recycled titanium tungsten powder, 25 parts of virgin titanium dioxide and 2 parts of glass fiber are fed into a double spiral conical mixer for dry mixing. The dry mixing time is 20 minutes. After uniform mixing, the dry mixture is obtained.

[0102] (3) Wet mixing: The dry mixture is fed into a kneader, the active component solution is added, and the mixture is stirred for 10 minutes. Then the remaining 18 parts of deionized water are added in 3 batches, and the mixture is stirred for 10 minutes after each addition. Then 0.5 parts of carboxymethyl cellulose, 0.5 parts of polyethylene oxide and 0.8 parts of stearic acid are added, and the mixture is stirred for 30 minutes until a uniform catalyst sludge with good plasticity is formed.

[0103] (4) Aging: Take the catalyst mud out of the kneader and put it into a sealed container. Aging is carried out for 12 hours at a temperature of 30℃ and a relative humidity of 80% to make the moisture and additives in the mud evenly distributed and improve the plasticity and molding performance of the mud.

[0104] (5) Extrusion molding: The aged catalyst sludge is fed into a vacuum sludge mill for sludge ...

[0105] (6) Drying: The extruded honeycomb catalyst preform is sent to a microwave drying chamber for microwave drying. The microwave frequency is 2450MHz, the power density is 1.0, and the drying time is 2 hours. The preform is dried until the moisture content is 10%. Then it is sent to a hot air drying chamber for hot air drying. The hot air drying is divided into three stages: the first stage temperature is 60℃, the relative humidity is 80%, and the drying time is 6 hours; the second stage temperature is 80℃, the relative humidity is 60%, and the drying time is 8 hours; the third stage temperature is 100℃, the relative humidity is 40%, and the drying time is 4 hours. The preform is dried until the moisture content is 0.6%.

[0106] (7) Calcination: The dried catalyst blank is sent into a tunnel kiln for calcination. The calcination atmosphere is air. The calcination process is divided into four stages: Heating stage: The temperature is increased from room temperature to 200℃ at a rate of 1℃ / min and held for 2 hours to remove residual moisture and volatile components from the green body. Low-temperature calcination stage: The temperature is increased from 200℃ to 400℃ at a rate of 1℃ / min and held for 4 hours to decompose organic additives such as carboxymethyl cellulose and polyethylene oxide. High-temperature calcination stage: The temperature is increased from 400℃ to 550℃ at a rate of 0.5℃ / min and held for 8 hours to allow the active components to fully combine with the support and form stable catalytic active centers. Cooling stage: The calcination temperature is reduced to 200℃ at a cooling rate of 1℃ / min, and then naturally cooled to room temperature to obtain the denitrification catalyst product with a high regenerated support ratio.

[0107] (8) Post-processing and packaging: The calcined catalyst product is cut and polished to remove burrs and edges, and then subjected to appearance inspection and size measurement to obtain a denitrification catalyst with a high regenerated support ratio. The qualified catalyst products are subjected to hardening end treatment, in which a hardening agent is impregnated at both ends of the catalyst. The hardening agent is a mixture of silica sol and alumina sol, with a mass ratio of silica sol to alumina sol of 1:1, and the impregnation time is 10 min. Then, it is dried at a temperature of 100℃ for 2 h to obtain the packaged denitrification catalyst product. The packaged products are classified and packaged according to specifications and stored in the warehouse.

[0108] Example 4: Step 1: Preparation of high-quality recycled titanium-tungsten powder: (1) Mechanical ash removal: The collected waste SCR denitrification catalyst modules with broken mechanical structure and sintering that do not meet the conditions for regeneration are disassembled, and the metal frame and sealing material are removed to obtain waste catalyst blocks; the waste catalyst blocks are sent to a jaw crusher for primary crushing to crush to a particle size of less than 50 mm, and then sent to a hammer crusher for secondary crushing to crush to a particle size of less than 5 mm; the crushed waste catalyst particles are sent to a vibrating screen for screening, the material on the screen is returned to the hammer crusher for further crushing, and the material under the screen is sent to a pneumatic conveying system for pneumatic conveying and mechanical ash removal by compressed air to remove loose dust and agglomerated impurities on the surface of the catalyst particles and collect waste catalyst coarse powder.

[0109] (2) High-pressure slitting: The waste catalyst coarse powder is fed into the high-pressure slitting device, and deionized water is added to make a slurry with a solid content of 30%. High-pressure slitting is carried out under the conditions of pressure of 20MPa and temperature of 40℃ for 60min. During the slitting process, fatty alcohol polyoxyethylene ether is added as a permeating agent. The amount of fatty alcohol polyoxyethylene ether added is 0.3% of the weight of the waste catalyst coarse powder. After the slitting is completed, the slurry is sent to the plate and frame filter press for the first filtration to obtain the first filter cake and the first filtrate. The first filtrate contains soluble impurities such as vanadium, potassium and sodium, and is sent to the subsequent vanadium-tungsten cascade separation process.

[0110] (3) Ultrasonic chemical cleaning: The first filter cake is sent into an ultrasonic cleaning tank, and deionized water is added to make a slurry with a solid content of 25%. The ultrasonic cleaning is carried out at an ultrasonic frequency of 20kHz and a power density of 1.0W / cm³. 2Ultrasonic chemical cleaning was performed at a temperature of 50℃ for 80 minutes. During the cleaning process, disodium ethylenediaminetetraacetate (EDTA-2Na) was added as a complexing agent. The amount of disodium ethylenediaminetetraacetate added was 0.2% of the weight of the first filter cake. After ultrasonic chemical cleaning, the slurry was sent to a plate and frame filter press for a second filtration to obtain a second filter cake and a second filtrate. The second filtrate contained soluble iron, arsenic and other impurities, and was sent to the wastewater treatment system.

[0111] (4) Alkaline arsenic removal: The second filter cake is fed into the reactor, and deionized water is added to make a slurry with a solid content of 20%. After stirring evenly, an alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate. The mass ratio of sodium hydroxide to sodium bicarbonate is 1:2. The amount of alkaline cleaning agent added is 1% of the weight of the second filter cake. The reaction is carried out at a temperature of 80℃ and a stirring speed of 400r / min for 2 hours. After the reaction is completed, the slurry is sent to a plate and frame filter press for a third filtration to obtain the third filter cake and the third filtrate. The third filtrate contains impurities such as arsenate and is sent to the wastewater treatment system.

[0112] (5) Electromagnetic iron removal: The third filter cake is sent to the drying oven and dried at 105℃ for 20h. Then it is sent to the pulverizer for pulverization until the particle size is less than 0.15mm. The pulverized powder is sent to the electromagnetic iron remover for electromagnetic iron removal. The magnetic field strength of the electromagnetic iron remover is 10000 Gauss and the iron removal time is 20min to remove solid magnetic iron impurities and obtain the iron-removed powder.

[0113] (6) Pulping and activation: The iron-removed powder is sent to the activation tank, and deionized water is added to make a slurry with a solid content of 30%. After stirring evenly, an organic complexing agent is added. The organic complexing agent is a mixture of citric acid and oxalic acid. The mass ratio of citric acid to oxalic acid is 3:1. The amount of organic complexing agent added is 1.5% of the weight of the iron-removed powder. The slurry is activated for 3 hours at a temperature of 70℃ and a stirring speed of 300r / min to remove soluble iron and aluminum impurities. After activation, the slurry is sent to a plate and frame filter press for the fourth filter press to obtain the fourth filter cake and the fourth filtrate. The fourth filtrate is sent to the wastewater treatment system.

[0114] (7) Acid leaching for impurity removal: The fourth filter cake is fed into the acid leaching reactor, and sulfuric acid solution is added to prepare a slurry with a solid content of 15% and a sulfuric acid solution concentration of 3 mol / L; acid leaching is carried out at a temperature of 100℃ and a stirring speed of 400 r / min for 6 hours; air is introduced during the acid leaching process at a flow rate of 0.5 m³ / min. 3 / (m 3 (min) to promote the oxidation and dissolution of impurities; after acid leaching, the slurry is sent to a plate and frame filter press for the fifth filtration to obtain the fifth filter cake and the fifth filtrate. The fifth filtrate contains valuable metals such as vanadium and tungsten, which are sent to the subsequent vanadium-tungsten cascade separation process.

[0115] (8) Vanadium-tungsten cascade separation: The first and fifth filtrates are mixed and sent to the extraction tank. Vanadium is extracted by adding an extractant, which is a mixture of di(2-ethylhexyl)phosphoric acid (P204) and sulfonated kerosene. The volume ratio of P204 to sulfonated kerosene is 1:5, the extraction ratio (O / A) is 1:4, the extraction time is 20 min, and the number of extraction stages is 5. After extraction, the vanadium-loaded organic phase is sent to the back-extraction tank. Sodium hydroxide solution is added for back-extraction. The concentration of sodium hydroxide solution is 4 mol / L, the back-extraction ratio (O / A) is 5:1, the back-extraction time is 15 min, and the number of back-extraction stages is 3. Vanadium-containing back-extraction liquid is obtained and used to prepare vanadium products. The raffinate mainly contains tungsten and is sent to the tungsten recovery process. Tungsten products are obtained by evaporation, concentration, and crystallization.

[0116] (9) Crystallization reconstruction: The fifth filter cake is fed into a pulping tank, and deionized water is added to make a slurry with a solid content of 20%. After stirring evenly, titanium source and tungsten source are added. The titanium source is titanium oxysulfate, and the tungsten source is ammonium paratungstate. The amount of titanium source added is 10% of the weight of the fifth filter cake, and the amount of tungsten source added is 1% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 10 with ammonia water. The reaction is carried out for 4 hours at a temperature of 80℃ and a stirring speed of 300r / min to carry out the crystallization reconstruction of the titanium-tungsten carrier. After the reaction is completed, the slurry is sent to a plate and frame filter press for the sixth filtration to obtain the sixth filter cake and the sixth filtrate. The sixth filtrate is sent to the wastewater treatment system.

[0117] (10) Drying, pulverizing and gravity screening: The sixth filter cake is sent to a flash dryer for drying. The inlet temperature is 350℃, the outlet temperature is 150℃, and the drying time is 10s. The dried powder is sent to an air jet mill for pulverizing until the average particle size is 5μm. Then it is sent to a gravity screen for gravity screening to remove impurities with high density such as silicon and aluminum, and obtain high-quality recycled titanium tungsten powder.

[0118] Step 2: Preparation of denitration catalyst with high doping ratio on regenerated support: Weigh out 85 parts by weight of high-quality recycled titanium tungsten powder, 10 parts of virgin titanium dioxide, 1 part of ammonium metavanadate, 4 parts of ammonium paratungstate, 6 parts of glass fiber, 2 parts of carboxymethyl cellulose, 0.1 parts of polyethylene oxide, 0.2 parts of stearic acid, 3 parts of citric acid, and 40 parts of deionized water.

[0119] (1) Preparation of active component solution: 1 part ammonium metavanadate and 4 parts ammonium paratungstate were added to 10 parts deionized water, stirred evenly, and then 3 parts citric acid were added; the mixture was stirred for 30 min at a temperature of 80℃ and a stirring speed of 500 r / min until it was completely dissolved to obtain active component solution.

[0120] (2) Dry mixing: 85 parts of high-quality recycled titanium tungsten powder, 10 parts of virgin titanium dioxide and 6 parts of glass fiber are fed into a double spiral conical mixer for dry mixing. The dry mixing time is 40 minutes. After uniform mixing, the dry mixture is obtained.

[0121] (3) Wet mixing: The dry mixture is fed into a kneader, the active component solution is added, and the mixture is stirred for 20 minutes. Then the remaining 30 parts of deionized water are added in 5 portions, and the mixture is stirred for 5 minutes after each addition. Then 2 parts of carboxymethyl cellulose, 0.1 parts of polyethylene oxide and 0.2 parts of stearic acid are added, and the mixture is stirred for 60 minutes until a uniform catalyst slurry with good plasticity is formed.

[0122] (4) Aging: Take the catalyst mud out of the kneader and put it into a sealed container. Aging is carried out for 24 hours at a temperature of 20℃ and a relative humidity of 60% to make the moisture and additives in the mud evenly distributed and improve the plasticity and molding performance of the mud.

[0123] (5) Extrusion molding: The aged catalyst sludge is fed into a vacuum sludge mill for sludge ...

[0124] (6) Drying: The extruded honeycomb catalyst preform is sent to a microwave drying chamber for microwave drying. The microwave frequency is 2450MHz, the power density is 0.5g, the drying time is 4 hours, and the moisture content of the preform is 15%. Then it is sent to a hot air drying chamber for hot air drying. The hot air drying is divided into three stages: the first stage temperature is 40℃, the relative humidity is 70%, and the drying time is 12h; the second stage temperature is 60℃, the relative humidity is 50%, and the drying time is 16h; the third stage temperature is 80℃, the relative humidity is 30%, and the drying time is 8h. The hot air drying is carried out until the moisture content of the preform is 0.8%.

[0125] (7) Calcination: The dried catalyst blank is sent into a tunnel kiln for calcination. The calcination atmosphere is air. The calcination process is divided into four stages: Heating stage: The temperature is increased from room temperature to 200℃ at a rate of 2℃ / min and held for 1 hour to remove residual moisture and volatile components from the green body; Low-temperature calcination stage: The temperature is increased from 200℃ to 400℃ at a rate of 2℃ / min and held for 2 hours to decompose organic additives such as carboxymethyl cellulose and polyethylene oxide; High-temperature calcination stage: The temperature is increased from 400℃ to 600℃ at a rate of 1℃ / min and held for 4 hours to allow the active components to fully combine with the support and form stable catalytic active centers. Cooling stage: The temperature is reduced from the calcination temperature to 200℃ at a cooling rate of 2℃ / min, and then naturally cooled to room temperature to obtain the denitrification catalyst product with a high regenerated support ratio.

[0126] (8) Post-processing and packaging: The calcined catalyst product is cut and polished to remove burrs and edges, and then subjected to appearance inspection and size measurement to obtain a denitrification catalyst with a high regenerated support ratio. The qualified catalyst products are subjected to hardening treatment, in which a hardening agent is impregnated at both ends of the catalyst. The hardening agent is a mixture of silica sol and alumina sol, with a mass ratio of silica sol to alumina sol of 2:1 and an impregnation time of 5 min. Then, it is dried at a temperature of 120℃ for 1 h to obtain the packaged denitrification catalyst product. The packaged products are classified and packaged according to specifications and stored in the warehouse.

[0127] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the crystallization reconstruction step is not performed in the preparation process of the regenerated titanium tungsten powder, while the remaining steps and parameters are the same as in Example 1.

[0128] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the proportion of recycled titanium tungsten powder added to the catalyst formulation is 50 parts, and the proportion of virgin titanium dioxide added is 43 parts.

[0129] The catalysts prepared in Examples 1 and 2, as well as Comparative Examples 1 and 2, were all 900 mm in length and had a 20×20 pore size. The denitrification catalysts with high-doping ratios on the regenerated support prepared in Examples 1-2 and the denitrification catalysts prepared in Comparative Examples 1-2 were subjected to physicochemical and performance tests. The test items included microscopic specific surface area, radial compressive strength, axial compressive strength, hardened end wear strength, unhardened end wear strength, denitrification activity, and SO2 / SO3 conversion rate.

[0130] The catalyst activity and conversion rate test conditions are as follows: flue gas volume 190m³ 3 / h, temperature 380℃, NOx concentration 250mg / m³ 3(Dry basis, 6% O2), ammonia nitrogen molar ratio 1.05, water content 8.5%, oxygen content 3.8% (dry basis); SO2 concentration 250 mg / m³ 3 (Dry basis, 6% O2). The test results are shown in Table 1.

[0131] Table 1. Results of catalyst physicochemical and performance tests

[0132] Test results show that the high-dosage denitration catalysts with regenerated supports prepared in Examples 1-2 of this invention all possess excellent physical and catalytic properties, and all performance indicators meet the requirements for industrial applications. Compared with Comparative Example 1, the catalyst of Example 1 has a higher specific surface area and catalytic activity, indicating that the crystallization reconstruction step can effectively repair the pore structure of the spent catalyst support and improve the catalyst performance. Compared with Comparative Example 2, the catalyst of Example 1 still maintains good physical and catalytic properties even when the proportion of regenerated titanium-tungsten powder added is increased to 75 parts, indicating that the formulation and preparation process of this invention can achieve a high proportion of regenerated powder addition.

[0133] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A denitrification catalyst with a high doping ratio on a regenerated support, characterized in that, By weight, it includes 70-85 parts of high-quality recycled titanium tungsten powder, 10-25 parts of virgin titanium dioxide, 1-5 parts of ammonium metavanadate, 1-4 parts of ammonium paratungstate, 2-6 parts of glass fiber, 0.5-2 parts of carboxymethyl cellulose, 0.1-0.5 parts of polyethylene oxide, 0.2-0.8 parts of stearic acid, 1-3 parts of citric acid, and 25-40 parts of deionized water.

2. The denitrification catalyst with a high doping ratio on a regenerated support according to claim 1, characterized in that, By weight, it includes 75 parts of high-quality recycled titanium tungsten powder, 18 parts of virgin titanium dioxide, 3 parts of ammonium metavanadate, 2.5 parts of ammonium paratungstate, 4 parts of glass fiber, 1.2 parts of carboxymethyl cellulose, 0.3 parts of polyethylene oxide, 0.5 parts of stearic acid, 2 parts of citric acid, and 32 parts of deionized water.

3. The denitrification catalyst with a high doping ratio on a regenerated support according to claim 1 or 2, characterized in that, By mass percentage, high-quality recycled titanium-tungsten powder comprises 80%~90% titanium oxide, 5%~10% tungsten oxide, 0.1%~0.5% vanadium oxide, ≤0.01% potassium, ≤0.01% sodium, <0.005% arsenic, ≤0.05% iron, ≤0.1% aluminum, and ≤0.2% silicon. By weight percentage, the glass fiber contains ≥55% silica and ≥15% alumina.

4. The denitrification catalyst with a high doping ratio on a regenerated support according to claim 1 or 2, characterized in that, High-quality recycled titanium tungsten powder has a microscopic specific surface area >80m². 2 / g, with an average particle size of 2~5μm; The virgin titanium dioxide is anatase titanium dioxide with a purity ≥99.0% and a microscopic specific surface area of ​​80~100m². 2 / g, with an average particle size of 1~3μm; The glass fiber is alkali-free chopped glass fiber with a length of 3~6mm and a diameter of 9~13μm; The degree of substitution of carboxymethyl cellulose is 0.6~0.9, and the viscosity is 1000~3000 mPa. s; The molecular weight of polyethylene oxide is 2 million to 5 million.

5. A method for preparing a denitrification catalyst with a high doping ratio on a regenerated support as described in any one of claims 1 to 4, characterized in that, include: High-quality recycled titanium-tungsten powder was prepared using waste SCR denitrification catalyst; Ammonium metavanadate and ammonium paratungstate were added to deionized water, citric acid was added, and the mixture was heated and stirred to obtain an active component solution. High-quality recycled titanium tungsten powder, virgin titanium dioxide and glass fiber are dry-mixed evenly to obtain a dry mixture; Add the dry mixture to the active component solution, add the remaining deionized water in 3 to 5 portions during the stirring process, and then add carboxymethyl cellulose, polyethylene oxide and stearic acid to form catalyst slurry; After aging, the catalyst sludge is vacuum-kneaded and extruded into honeycomb-shaped catalyst blanks. The honeycomb catalyst preform is dried, calcined, and post-treated to obtain a denitrification catalyst with a high doping ratio on a regenerated support.

6. The method for preparing the denitrification catalyst with a high doping ratio on the regenerated support according to claim 5, characterized in that, Methods for preparing high-quality recycled titanium tungsten powder include: The spent SCR denitrification catalyst module was disassembled to obtain spent catalyst blocks; The waste catalyst blocks are crushed to a particle size of less than 5 mm, then screened and pneumatically conveyed to remove ash, to obtain coarse powder of the waste catalyst. The spent catalyst coarse powder was made into a slurry with a solid content of 20%~30%, and was subjected to high-pressure sliding washing under the conditions of pressure of 10~20MPa and temperature of 40~60℃ for 30~60min. During the sliding washing process, fatty alcohol polyoxyethylene ether was added as a permeating agent, and the amount of permeating agent added was 0.1%~0.3% of the weight of spent catalyst coarse powder. After the sliding washing was completed, the first pressure filtration was performed to obtain the first filter cake and the first filtrate. The first filter cake is prepared into a slurry with a solid content of 15% to 25%, and then subjected to ultrasonic treatment at a frequency of 20 to 40 kHz and a power density of 0.5 to 1.0 W / cm³. 2 Ultrasonic chemical cleaning is performed at a temperature of 50~70℃ for 40~80 minutes. Disodium ethylenediaminetetraacetate is added as a complexing agent during the cleaning process. The amount of complexing agent added is 0.2%~0.5% of the weight of the first filter cake. After cleaning, a second pressure filtration is performed to obtain the second filter cake and the second filtrate. The second filter cake is made into a slurry with a solid content of 10%~20%. An alkaline cleaning agent is added. The alkaline cleaning agent is a mixture of sodium hydroxide and sodium bicarbonate with a mass ratio of sodium hydroxide to sodium bicarbonate of 1:2~4. The amount of alkaline cleaning agent added is 1%~3% of the weight of the second filter cake. The reaction is carried out at a temperature of 60~80℃ and a stirring speed of 200~400r / min for 2~4h. After the reaction is completed, a third pressure filtration is performed to obtain the third filter cake and the third filtrate. After drying the third filter cake, it is pulverized to a particle size of less than 0.15 mm, and then electromagnetic iron removal is performed under a magnetic field strength of 10000~15000 Gauss for 10~20 min to obtain iron-removed powder. After iron removal, the powder is made into a slurry with a solid content of 20% to 30%. An organic complexing agent is added, which is a mixture of citric acid and oxalic acid with a mass ratio of 2 to 3:

1. The amount of organic complexing agent added is 0.5% to 1.5% of the weight of the powder after iron removal. The mixture is activated for 1 to 3 hours at a temperature of 50 to 70°C and a stirring speed of 300 to 500 r / min. After activation, the mixture is filtered for the fourth time to obtain the fourth filter cake and the fourth filtrate. A sulfuric acid solution was added to the fourth filter cake to prepare a slurry with a solid content of 15%–25%. Acid leaching was then carried out at a temperature of 80–100℃ and a stirring speed of 400–600 r / min. The concentration of the sulfuric acid solution was 1–3 mol / L, and the leaching time was 3–6 h. Air was introduced during the leaching process at a flow rate of 0.5–1.0 m³ / min. 3 / (m 3 (min); After acid leaching, a fifth pressure filtration is performed to obtain the fifth filter cake and the fifth filtrate; The first and fifth filtrates were mixed, and an extractant was added for vanadium extraction. The extractant was a mixture of di(2-ethylhexyl)phosphoric acid and sulfonated kerosene, with a volume ratio of di(2-ethylhexyl)phosphoric acid to sulfonated kerosene of 1:3~5, an extraction ratio of 1:2~4, an extraction time of 10~20 min, and 3~5 extraction stages. After extraction, the vanadium-loaded organic phase was back-extracted with sodium hydroxide solution, with a concentration of 2~4 mol / L, a back-extraction ratio of 3~5:1, a back-extraction time of 15~30 min, and 2~3 back-extraction stages, to obtain a vanadium-containing back-extraction solution. The fifth filter cake is prepared into a slurry with a solid content of 20% to 30%. A titanium source and a tungsten source are added. The titanium source is titanium oxysulfate and the tungsten source is ammonium paratungstate. The amount of titanium source added is 5% to 10% of the weight of the fifth filter cake, and the amount of tungsten source added is 1% to 3% of the weight of the fifth filter cake. The pH value of the slurry is adjusted to 8 to 10 with ammonia water. The reaction is carried out at a temperature of 60 to 80°C and a stirring speed of 300 to 500 r / min for 2 to 4 hours. After the reaction is completed, a sixth pressure filtration is performed to obtain the sixth filter cake and the sixth filtrate. The sixth filter cake was flash-dried at an inlet temperature of 300-350℃ and an outlet temperature of 120-150℃ for 10-30 seconds. It was then pulverized to an average particle size of 2-5μm and subjected to gravity screening to obtain high-quality recycled titanium tungsten powder.

7. The method for preparing the denitrification catalyst with a high doping ratio on the regenerated support according to claim 5, characterized in that, The heating and stirring temperature is 60~80℃, the stirring speed is 300~500r / min, and the stirring time is 30~60min.

8. The method for preparing the denitrification catalyst with a high doping ratio on the regenerated support according to claim 5, characterized in that, The aging temperature is 20~30℃, the relative humidity is 60%~80%, and the aging time is 12~24h; The vacuum kneading process is repeated 2-3 times, with a vacuum level of (-0.08) to (-0.095) MPa. The extrusion molding pressure is 8~12MPa, and the extrusion speed is 0.5~1.0m / min.

9. The method for preparing the denitrification catalyst with a high doping ratio on the regenerated support according to claim 5, characterized in that, The drying process of the honeycomb catalyst preform involves first microwave drying until the moisture content of the preform is 10%~15%, and then hot air drying until the moisture content of the preform is less than 1%. During the microwave drying process, the microwave frequency is 2450MHz, the power density is 0.5~1.0W / g, and the drying time is 2~4h. Hot air drying consists of three stages: the first stage has a temperature of 40~60℃, a relative humidity of 70%~80%, and a drying time of 6~12h; the second stage has a temperature of 60~80℃, a relative humidity of 50%~60%, and a drying time of 8~16h; and the third stage has a temperature of 80~100℃, a relative humidity of 30%~40%, and a drying time of 4~8h.

10. The method for preparing the denitrification catalyst with a high doping ratio on the regenerated support according to claim 5, characterized in that, The calcination atmosphere is air, and the calcination process includes a heating stage, a low-temperature calcination stage, a high-temperature calcination stage, and a cooling stage. During the heating phase, the temperature is increased from room temperature to 200℃ at a rate of 1~2℃ / min, and then held for 1~2 hours. During the low-temperature calcination stage, the temperature is increased from 200℃ to 400℃ at a rate of 1~2℃ / min, and held for 2~4 hours. During the high-temperature calcination stage, the temperature is increased from 400℃ to 550-600℃ at a rate of 0.5-1℃ / min, and held for 4-8 hours. During the cooling stage, the temperature is reduced from the calcination temperature to 200℃ at a rate of 1~2℃ / min, and then naturally cooled to room temperature.

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