Regeneration method of palladium catalyst for hydrogen peroxide

Abstract

The invention discloses a regeneration method of a palladium catalyst for hydrogen peroxide, and belongs to the technical field of catalyst regeneration, the regeneration method comprises the following steps: grading, ball milling, primary mixing, hydrothermal synthesis, molding, primary treatment, secondary treatment and secondary mixing; in the grading step, the to-be-regenerated palladium catalyst particles are graded according to the particle size, the to-be-regenerated palladium catalyst particles with the particle size larger than or equal to 2 mm serve as complete palladium catalyst particles, and the to-be-regenerated palladium catalyst particles with the particle size smaller than 2 mm serve as broken palladium catalyst particles; the palladium catalyst particles regenerated through the regeneration method are long in service cycle, the palladium catalyst particles uniform in particle size can be obtained after regeneration aiming at the problems of breaking and desorption of the palladium catalyst particles in a fluidized bed method for catalyzing through the palladium catalyst, and the palladium catalyst does not need to be dissolved.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst regeneration, and in particular to a method for regenerating a palladium catalyst for hydrogen peroxide. Background Art

[0002] Hydrogen peroxide, also known as hydrogen peroxide aqueous solution, is a colorless transparent liquid with a slightly pungent odor. It is mainly used as a strong oxidant and disinfectant and is widely used in sterilization, sewage treatment, dyeing and weaving, bleaching and other fields. The mass concentration of commonly used hydrogen peroxide is 3-30%. The higher the mass concentration of hydrogen peroxide, the stronger the oxidizing property.

[0003] The production methods of hydrogen peroxide include anthraquinone method, ammonium persulfate electrolysis method, isopropanol oxidation method, oxygen cathode electrolytic reduction method, and direct hydrogen-oxygen synthesis method, among which the most commonly used production method is anthraquinone method. Taking advantage of the property that quinone substances can be converted back to quinone substances through oxidation after being hydrogenated and reduced, the anthraquinone method is to dissolve alkyl anthraquinone in an organic solvent to obtain an alkyl anthraquinone solution, and then hydrogenate and reduce the alkyl anthraquinone in the alkyl anthraquinone solution under the action of a hydrogenation catalyst to obtain the corresponding alkyl hydroanthraquinone, and then oxidize it to generate hydrogen peroxide, and at the same time convert the alkyl hydroanthraquinone back to alkyl anthraquinone, and then use pure water to extract the generated hydrogen peroxide to obtain hydrogen peroxide, and then treat the alkyl anthraquinone solution for recycling.

[0004] According to the difference in reaction apparatus and catalyst, the anthraquinone method is mainly divided into a suspended kettle method catalyzed by a nickel catalyst, a fixed bed method catalyzed by a palladium catalyst, and a fluidized bed method catalyzed by a palladium catalyst. Compared with the suspended kettle method catalyzed by a nickel catalyst, the fixed bed method catalyzed by a palladium catalyst and the fluidized bed method catalyzed by a palladium catalyst have the advantages of less catalyst dosage, high catalyst activity, and easy catalyst regeneration. Therefore, the commonly used methods for producing hydrogen peroxide at present are the fixed bed method catalyzed by a palladium catalyst and the fluidized bed method catalyzed by a palladium catalyst.

[0005] Unlike the fixed bed method catalyzed by palladium catalyst, in the fluidized bed method catalyzed by palladium catalyst, during the hydrogenation reduction, the palladium catalyst particles, as the dispersed phase of the alkylhydroanthraquinone solution, will always be in a suspended motion state with the flow of alkylhydroanthraquinone. The active sites on the surface of the palladium catalyst particles can adsorb hydrogen and activate the hydrogen to an atomic state. At the same time, the palladium catalyst particles can also adsorb alkylanthraquinone through the active sites on the surface. Then the active sites on the surface of the palladium catalyst particles can promote the reaction of hydrogen atoms with alkylanthraquinone to obtain the corresponding alkylhydroanthraquinone. The alkylhydroanthraquinone is desorbed and separated from the active sites on the surface of the palladium catalyst particles. The active sites on the surface of the palladium catalyst particles re-adsorb hydrogen and alkylanthraquinone to continue to promote the reaction of hydrogen with the remaining alkylanthraquinone. The fluidized bed method catalyzed by palladium catalyst is more conducive to the replenishment of palladium catalyst, and can also achieve fully acidic reaction conditions, avoiding the use of acidic production conditions and alkaline production conditions alternately in some fixed bed methods catalyzed by palladium catalysts, resulting in the risk of explosion caused by the violent decomposition reaction of hydrogen peroxide that may accidentally enter the alkaline environment. However, the fluidized bed method catalyzed by palladium catalyst will accelerate the breakage of palladium catalyst particles. In order to prevent the palladium catalyst from being lost with the alkylhydroanthraquinone solution, the alkylhydroanthraquinone solution is filtered in the fluidized bed method catalyzed by palladium catalyst, and the filter residue obtained is regenerated and continued to be used.

[0006] In the fluidized bed method catalyzed by palladium catalyst, there is also the problem of palladium catalyst failure. The palladium catalyst in the currently commonly used palladium catalyst particles is mainly a supported palladium catalyst with porous alumina as a carrier. When preparing palladium catalyst particles, the palladium precursor is first mixed with a porous alumina carrier with a high specific surface area, and the palladium precursor is uniformly adsorbed on the surface of the porous alumina carrier with a high specific surface area. Then, the palladium precursor supported on the surface of the porous alumina carrier is converted into palladium black to obtain a supported palladium catalyst. In long-term use, macromolecular by-products will block the pores of the porous alumina carrier in the palladium catalyst particles, and will also cover the surface of the palladium catalyst, thereby causing the palladium catalyst to fail. In view of the failure of the palladium catalyst, the most commonly used regeneration method is to remove the macromolecular by-products by high-temperature water washing or saturated water vapor treatment.

[0007] However, when high-temperature water washing or saturated steam treatment is used to regenerate the palladium catalyst particles in the fluidized bed method catalyzed by a palladium catalyst, the following problems exist: first, the removal capacity of high-temperature water washing or saturated steam treatment is limited, and it is difficult to penetrate into the pores of the porous carrier to remove the macromolecular by-products, resulting in a reduction in the active sites of the palladium catalyst particles after regeneration and a decrease in activity, which is specifically manifested in a shortened service life of the palladium catalyst particles after regeneration; second, the fluidized bed method catalyzed by a palladium catalyst accelerates the crushing of the palladium catalyst particles while also causing the desorption of the palladium catalyst on the surface of the palladium catalyst particles, resulting in the filter residue obtained after filtering the alkylhydroanthraquinone solution being palladium catalyst particles with inconsistent particle sizes and desorbed palladium black, and the use of high-temperature water washing or saturated steam treatment will cause the desorbed palladium black to be lost, and the palladium catalyst particles with inconsistent particle sizes will have an uneven distribution problem in the fluidized bed after regeneration, and the palladium catalyst particles with small particle sizes will gather at a position far away from the tuyere, and the palladium catalyst particles with large particle sizes will gather at a position close to the tuyere. The uneven distribution of the palladium catalyst particles will cause the displacement of the reaction area, further affecting the reaction rate of the hydrogenation reduction.

[0008] To address the above problems, the commonly used methods are: first, using organic solvents and alkaline solutions for soaking to remove the macromolecular by-products inside the pores of the porous alumina carrier, but the soaking will cause the desorbed palladium black to be further lost, and the service life of the palladium catalyst particles after regeneration will be further shortened; second, for the broken palladium catalyst particles, they need to be thoroughly crushed, and the palladium catalyst is dissolved by inorganic acid and oxidant before reloading, conversion, and molding. However, in this method, the palladium catalyst will be lost during the dissolution process and the reloading process. Summary of the invention

[0009] In view of the shortcomings of the prior art, the present invention provides a method for regenerating a palladium catalyst for hydrogen peroxide. The regenerated palladium catalyst particles have a long service life and can solve the problems of crushing and desorption of palladium catalyst particles in a fluidized bed method catalyzed by a palladium catalyst. After regeneration, palladium catalyst particles with uniform particle size can be obtained without dissolving the palladium catalyst.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for regenerating a palladium catalyst for hydrogen peroxide, comprising: grading, ball milling, primary mixing, hydrothermal synthesis, molding, primary treatment, secondary treatment, and secondary mixing; The classification includes classifying the palladium catalyst particles to be regenerated according to their particle size, classifying the palladium catalyst particles to be regenerated with a particle size greater than or equal to 2 mm as complete palladium catalyst particles, and classifying the palladium catalyst particles to be regenerated with a particle size less than 2 mm as broken palladium catalyst particles; In the classification, the carrier of the palladium catalyst particles to be regenerated is porous alumina, the original palladium content is 0.307wt%, the original particle size is 2mm, and the original specific surface area is 120m 2 / g, the original bulk density is 0.65g / mL, and the original pore volume is 0.60mL / g; The ball milling comprises placing the crushed palladium catalyst particles into a planetary ball mill and performing ball milling at room temperature, collecting the material in the planetary ball mill after the ball milling is completed, separating the alumina grinding balls from the material, and classifying the remaining material according to the particle size, wherein the material with a particle size less than 100 μm is regarded as a small particle size material, and the material with a particle size greater than or equal to 100 μm is regarded as a large particle size material; In the ball milling, the grinding balls in the planetary ball mill are alumina grinding balls, the particle size of the alumina grinding balls is 6 mm, the ball-to-material ratio is 5-6:1, the ball milling speed is 130-150 rpm, and the ball milling time is 9-10 min; The primary mixing comprises adding deionized water and aluminum chloride to the small particle size material, stirring at 70-80° C. at a stirring speed of 50-100 rpm for 20-30 min, adding the triblock copolymer P123, and continuing stirring for 20-30 min to obtain a primary mixed solution; In the primary mixing, the usage ratio of the small particle size material, deionized water, aluminum chloride, and triblock copolymer P123 is 102-105 g: 1.7-1.8 L: 10-11 g: 9-10 g; The hydrothermal synthesis comprises mixing the primary mixed solution, urea and polystyrene microspheres, stirring at room temperature at a stirring speed of 50-100 rpm for 20-30 minutes, hydrothermally reacting at 150-160° C. for 9-10 hours, centrifuging and collecting a precipitate, washing the precipitate with water and drying it to obtain composite microspheres; In the hydrothermal synthesis, the particle size of the polystyrene microspheres is 500 nm; The dosage ratio of the primary mixed liquid, urea, and polystyrene microspheres is 1.7-1.8L: 20-25g: 0.5-0.52g; The molding comprises adding the large-particle material, the composite microspheres, gum arabic and deionized water into a mixer and mixing them evenly, and then pressing them into spheres with a particle size of 2 mm, and then calcining them at 400-450° C. for 2-2.5 hours in a nitrogen atmosphere to obtain a spherical catalyst; In the molding, the mass ratio of the total mass of the large-particle material and the composite microspheres to the mass ratio of gum arabic and deionized water is 1000:20-23:1100-1200; The one-time treatment comprises: loading the spherical catalyst into the constant temperature section of the fixed bed, filling the upper and lower parts with quartz sand, and then soaking the spherical catalyst in toluene. After the soaking, the toluene is released, and the catalyst is purged once with nitrogen. After the one-time purge, the catalyst is cleaned once with water vapor. After the one-time cleaning, the catalyst is cleaned twice with hot water. After the second cleaning, the catalyst is purged twice with a mixed gas of nitrogen and hydrogen. After the second purge, the catalyst is taken out and dried to obtain a first portion of palladium catalyst. In the one-time treatment, the volume ratio of toluene to the spherical catalyst used in the soaking is 6-7:1, the soaking temperature is 50-60° C., and the soaking time is 30-33 h; The flow rate of nitrogen in the primary purge is 480-520 mL / min, the temperature of the primary purge is 50-60° C., and the time is 6-7 h; The flow rate of water vapor in the first cleaning is 180-200 mL / h, the temperature is 100-110° C., and the time is 19-20 h; The flow rate of hot water in the secondary cleaning is 120-130 mL / h, the temperature is 100° C., and the time is 8-9 h; The flow rate of the mixed gas of nitrogen and hydrogen in the secondary purge is 480-520 mL / min, the temperature of the secondary purge is 70-80° C., and the time is 1.5-2 h; The volume ratio of nitrogen to hydrogen in the mixed gas of nitrogen and hydrogen is 4-5:1; The secondary treatment comprises: loading the complete palladium catalyst particles into the constant temperature section of the fixed bed, filling the upper and lower parts with quartz sand, and then soaking them with the mixed solution, while soaking, introducing nitrogen into the mixed solution in the fixed bed for a purge, introducing the nitrogen into the mixed solution from the bottom of the fixed bed, and ending the purge at the same time as the soaking, and then washing them once with water vapor, washing them twice with hot water after the first washing, and then purge them twice with nitrogen after the second washing, taking out the catalyst after the second purge, and drying it to obtain the second portion of palladium catalyst; In the secondary treatment, the volume ratio of the mixed solution used in the immersion to the complete palladium catalyst particles is 3.8-4:1, the immersion temperature is 50-60° C., and the immersion time is 30-33 hours; The flow rate of nitrogen in the primary purge is 700-750 mL / min; The flow rate of water vapor in the first cleaning is 180-200 mL / h, the temperature is 100-110° C., and the time is 12-13 h; The flow rate of hot water in the secondary cleaning is 120-130 mL / h, the temperature is 100° C., and the time is 5-6 h; The flow rate of nitrogen in the secondary purge is 480-520 mL / min, the temperature of the secondary purge is 50-60° C., and the time is 1.5-2 h.

[0011] The mixed liquid is a mixture of toluene and triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone, wherein the volume ratio of toluene to the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 100:0.9-1, and the molecular weight ratio of polycaprolactone to polyethylene glycol in the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 0.85:1; The secondary mixing is to mix the first portion of the palladium catalyst and the second portion of the palladium catalyst evenly to obtain a regenerated palladium catalyst.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The regeneration method of the palladium catalyst for hydrogen peroxide of the present invention is designed to solve the problem that the palladium catalyst particles are easily broken in the fluidized bed method catalyzed by the palladium catalyst. Since the palladium catalyst on the surface will be desorbed after being broken, the broken palladium catalyst particles are first ball-milled to grind the aluminum oxide on the surface into powder, and the heat generated by the ball milling promotes the binding force between the palladium and the carrier in the broken palladium catalyst particles, and can also promote the decomposition of the macromolecular byproducts in the broken palladium catalyst particles, which is convenient for subsequent removal. Then, the powder after ball milling is treated. Since the main The invention relates to a method for preparing a palladium catalyst and an alumina powder. The method comprises mixing the palladium catalyst and the alumina powder with water and aluminum chloride first, and then adding the triblock copolymer P123 after mixing. The triblock copolymer P123 and the aluminum chloride are adsorbed on the palladium catalyst and the alumina powder to promote the dispersion of the palladium catalyst and the alumina powder. Then, the method carries out hydrothermal synthesis. The polystyrene microspheres are used as templates. The palladium catalyst and the alumina powder after the triblock copolymer P123 and the aluminum chloride are adsorbed on the polystyrene microspheres. After the hydrothermal synthesis, the aluminum chloride is converted into nano-sized alumina, thereby obtaining a combination of nano-sized alumina, the palladium catalyst, the alumina powder, the triblock copolymer P123, and the polystyrene microspheres. Through hydrothermal synthesis, on the one hand, the dispersion of the palladium catalyst and the alumina powder can be promoted, and on the other hand, the detached palladium catalyst can be re-bonded to the alumina powder. The mixture is then mixed with the large-particle material after ball milling, and gum arabic is used as a binder to form a slurry. The slurry is then molded and calcined in a nitrogen atmosphere. During the calcination, the polystyrene microspheres and gum arabic are decomposed to finally obtain a porous spherical catalyst. The porous spherical catalyst is then treated once to remove impurities to obtain the first palladium catalyst. The intact palladium catalyst particles that have not been broken are then cleaned through a secondary treatment. In the secondary treatment, the particles soaked in the first treatment are Purging combined, using a mixture of toluene and triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone as a mixed liquid during immersion, directly introducing nitrogen into the mixed liquid during a purge, and the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone self-assembles into vesicles in toluene, and the vesicles can penetrate into the intact palladium catalyst particles that have not been broken under the purge of nitrogen to purge, and can also bind to macromolecular by-products to promote the dissolution of macromolecular by-products, and after the secondary treatment is completed, a second portion of palladium catalyst is obtained, and the first portion of palladium catalyst and the second portion of palladium catalyst are evenly mixed to obtain palladium catalyst particles with uniform particle size; (2) The regeneration method of the palladium catalyst for hydrogen peroxide of the present invention has a long service life of the palladium catalyst particles after regeneration. The palladium content of the palladium catalyst for hydrogen peroxide after regeneration is 0.301-0.302wt%, the hydrogen efficiency is 7.12-7.31g (H2O2) / L, and the specific surface area is 130-137m 2 / g; (3) The method for regenerating the palladium catalyst for hydrogen peroxide of the present invention can solve the problem of crushing and desorption of palladium catalyst particles in a fluidized bed process catalyzed by a palladium catalyst, and obtain palladium catalyst particles with uniform particle size after regeneration; (4) The method for regenerating the palladium catalyst for hydrogen peroxide of the present invention can solve the problem of crushing and desorption of palladium catalyst particles in a fluidized bed process catalyzed by a palladium catalyst without dissolving the palladium catalyst. DETAILED DESCRIPTION

[0013] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0014] Example 1 A method for regenerating a palladium catalyst for hydrogen peroxide, specifically: 1. Classification: The palladium catalyst particles to be regenerated are classified according to the particle size, and the palladium catalyst particles to be regenerated with a particle size greater than or equal to 2 mm are regarded as complete palladium catalyst particles, and the palladium catalyst particles to be regenerated with a particle size less than 2 mm are regarded as broken palladium catalyst particles; The carrier of the palladium catalyst particles to be regenerated is porous alumina, the original palladium content is 0.307wt%, the original particle size is 2mm, and the original specific surface area is 120m 2 / g, the original bulk density is 0.65g / mL, and the original pore volume is 0.60mL / g; 2. Ball milling: The crushed palladium catalyst particles are placed in a planetary ball mill and ball milled at room temperature. The grinding balls in the planetary ball mill are alumina grinding balls with a particle size of 6 mm, a ball-to-material ratio of 5:1, a ball milling speed of 130 rpm, and a ball milling time of 9 min. After the ball milling, the materials in the planetary ball mill are collected. After the alumina grinding balls are separated from the materials, the remaining materials are classified according to the particle size. The materials with a particle size of less than 100 μm are classified as small particle size materials, and the materials with a particle size of greater than or equal to 100 μm are classified as large particle size materials; 3. Primary mixing: add deionized water and aluminum chloride to the small particle size material, stir at 70°C at a stirring speed of 50 rpm for 20 min, add triblock copolymer P123, continue stirring for 20 min to obtain a primary mixed solution; The ratio of small particle size material, deionized water, aluminum chloride, and triblock copolymer P123 is 102 g:1.7 L:10 g:9 g; 4. Hydrothermal synthesis: After mixing the primary mixed solution, urea and polystyrene microspheres, stir at room temperature at a stirring speed of 50 rpm for 20 min, perform hydrothermal reaction at 150°C for 9 h, take out the precipitate after centrifugation, wash the precipitate with water and dry it to obtain composite microspheres; The particle size of the polystyrene microspheres is 500 nm; The dosage ratio of the primary mixed liquid, urea, and polystyrene microspheres is 1.7L:20g:0.5g; 5. Molding: Add all the large-particle materials obtained in the ball milling step of step 2, all the composite microspheres obtained in the hydrothermal synthesis step of step 4, gum arabic, and deionized water into a mixer and mix them evenly, then press them into spheres with a particle size of 2 mm, and then calcine them at 400° C. for 2 hours in a nitrogen atmosphere to obtain a spherical catalyst; The mass ratio of the total mass of the large-size material and the composite microspheres to the mass of gum arabic and deionized water is 1000:20:1100; 6. One-time treatment: all the spherical catalysts obtained in the forming step of step 5 are loaded into the constant temperature section of the fixed bed, filled with quartz sand on the top and bottom, and then soaked with toluene, the volume ratio of toluene to spherical catalyst used in the soaking is controlled to be 6:1, the soaking temperature is 50°C, the soaking time is 30h, and the toluene is released after the soaking, and nitrogen is used for a purge, and the flow rate of nitrogen in the purge is controlled to be 480mL / min, the purge temperature is 50°C, and the time is 6h. After the purge is completed, water vapor is used for cleaning, and the cleaning is controlled once. The flow rate of water vapor during washing is 180 mL / h, the temperature is 100° C., and the time is 19 h. After the first washing, hot water is used for secondary washing. The flow rate of hot water in the second washing is controlled to be 120 mL / h, the temperature is 100° C., and the time is 8 h. After the second washing, a mixed gas of nitrogen and hydrogen is used for secondary purge. The flow rate of the mixed gas of nitrogen and hydrogen in the second purge is controlled to be 480 mL / min, the temperature of the second purge is 70° C., and the time is 1.5 h. After the second purge, the catalyst is taken out and dried to obtain the first portion of palladium catalyst; The volume ratio of nitrogen to hydrogen in the mixed gas of nitrogen and hydrogen is 4:1; 7. Secondary treatment: All the complete palladium catalyst particles obtained in the first step of the classification step are loaded into the constant temperature section of the fixed bed, filled with quartz sand on the top and bottom, and then soaked with the mixed solution, and the volume ratio of the mixed solution used in the soaking to the complete palladium catalyst particles is controlled to be 3.8:1, the soaking temperature is 50°C, the soaking time is 30h, and nitrogen is introduced into the mixed solution in the fixed bed for a purge at the same time, starting from the bottom of the fixed bed, and the flow rate of nitrogen in the purge is controlled to be 700mL / min. The purge is ended at the end of the soaking, and then Then use water vapor to perform a cleaning, control the flow rate of water vapor in the cleaning to 180mL / h, the temperature to 100°C, and the time to 12h. After the first cleaning, use hot water to perform a second cleaning, control the flow rate of hot water in the second cleaning to 120mL / h, the temperature to 100°C, and the time to 5h. After the second cleaning, use nitrogen to perform a second purge, control the flow rate of nitrogen in the second purge to 480mL / min, the temperature of the second purge to 50°C, and the time to 1.5h. After the second purge, take out the catalyst and dry it to obtain a second portion of palladium catalyst; The mixed liquid is a mixture of toluene and triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone, wherein the volume ratio of toluene to the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 100:0.9, and the molecular weight ratio of polycaprolactone to polyethylene glycol in the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 0.85:1; 8. Secondary mixing: uniformly mix all of the first portion of palladium catalyst obtained in the primary treatment step of step 6 and all of the second portion of palladium catalyst obtained in the secondary treatment step of step 7 to obtain a regenerated palladium catalyst.

[0015] Example 2 A method for regenerating a palladium catalyst for hydrogen peroxide, specifically: 1. Classification: The palladium catalyst particles to be regenerated are classified according to the particle size, and the palladium catalyst particles to be regenerated with a particle size greater than or equal to 2 mm are regarded as complete palladium catalyst particles, and the palladium catalyst particles to be regenerated with a particle size less than 2 mm are regarded as broken palladium catalyst particles; The carrier of the palladium catalyst particles to be regenerated is porous alumina, the original palladium content is 0.307wt%, the original particle size is 2mm, and the original specific surface area is 120m 2 / g, the original bulk density is 0.65g / mL, and the original pore volume is 0.60mL / g; 2. Ball milling: The crushed palladium catalyst particles are placed in a planetary ball mill and ball milled at room temperature. The grinding balls in the planetary ball mill are alumina grinding balls with a particle size of 6 mm, a ball-to-material ratio of 5:1, a ball milling speed of 140 rpm, and a ball milling time of 10 min. After the ball milling, the materials in the planetary ball mill are collected, and after the alumina grinding balls are separated from the materials, the remaining materials are classified according to the particle size, and the materials with a particle size of less than 100 μm are classified as small particle size materials, and the materials with a particle size of greater than or equal to 100 μm are classified as large particle size materials; 3. Primary mixing: add deionized water and aluminum chloride to the small particle size material, stir at 75°C at a stirring speed of 80 rpm for 25 min, add triblock copolymer P123, continue stirring for 25 min to obtain a primary mixed solution; The dosage ratio of small particle size material, deionized water, aluminum chloride, and triblock copolymer P123 is 104 g:1.8 L:10.5 g:9.5 g; 4. Hydrothermal synthesis: After mixing the primary mixed solution, urea and polystyrene microspheres, stir at room temperature at a stirring speed of 80 rpm for 25 min, perform hydrothermal reaction at 155°C for 9.5 h, take out the precipitate after centrifugation, wash the precipitate with water and dry it to obtain composite microspheres; The particle size of the polystyrene microspheres is 500 nm; The dosage ratio of the primary mixed liquid, urea, and polystyrene microspheres is 1.8L:22g:0.51g; 5. Molding: Add all the large-particle materials obtained in the ball milling step of step 2, all the composite microspheres obtained in the hydrothermal synthesis step of step 4, gum arabic, and deionized water into a mixer and mix them evenly, then press them into spheres with a particle size of 2 mm, and then calcine them at 420° C. for 2.5 hours in a nitrogen atmosphere to obtain a spherical catalyst; The mass ratio of the total mass of the large-size material and the composite microspheres to the mass of gum arabic and deionized water is 1000:21:1150; 6. One-time treatment: all the spherical catalysts obtained in the forming step of step 5 are loaded into the constant temperature section of the fixed bed, filled with quartz sand on the top and bottom, and then soaked with toluene, the volume ratio of toluene to spherical catalyst used in the soaking is controlled to be 6:1, the soaking temperature is 55°C, the soaking time is 32h, and the toluene is released after the soaking, and nitrogen is used for a purge, the flow rate of nitrogen in the purge is controlled to be 500mL / min, the purge temperature is 55°C, and the time is 6.5h. After the purge is completed, water vapor is used for cleaning, and the cleaning is controlled once. The flow rate of water vapor during washing is 190 mL / h, the temperature is 105° C., and the time is 19.5 h. After the first washing is completed, hot water is used for secondary washing, and the flow rate of hot water in the secondary washing is controlled to be 125 mL / h, the temperature is 100° C., and the time is 8.5 h. After the second washing is completed, a mixed gas of nitrogen and hydrogen is used for secondary purge, and the flow rate of the mixed gas of nitrogen and hydrogen in the secondary purge is controlled to be 500 mL / min, the temperature of the secondary purge is 75° C., and the time is 2 h. After the second purge is completed, the catalyst is taken out and dried to obtain the first portion of palladium catalyst; The volume ratio of nitrogen to hydrogen in the mixed gas of nitrogen and hydrogen is 4.5:1; 7. Secondary treatment: All the complete palladium catalyst particles obtained in the first step of the classification step are loaded into the constant temperature section of the fixed bed, filled with quartz sand on the top and bottom, and then soaked with the mixed solution, and the volume ratio of the mixed solution used in the soaking to the complete palladium catalyst particles is controlled to be 3.9:1, the soaking temperature is 55°C, and the soaking time is 32h. While soaking, nitrogen is passed into the mixed solution in the fixed bed for a purge, starting from the bottom of the fixed bed, and the flow rate of nitrogen in the purge is controlled to be 720mL / min. The purge is ended at the end of the soaking, and then Use water vapor to perform a primary cleaning, control the flow rate of water vapor in the primary cleaning to be 190 mL / h, the temperature to be 105° C., and the time to be 12.5 h; after the primary cleaning, use hot water to perform a secondary cleaning, control the flow rate of hot water in the secondary cleaning to be 125 mL / h, the temperature to be 100° C., and the time to be 5.5 h; after the secondary cleaning, use nitrogen to perform a secondary purge, control the flow rate of nitrogen in the secondary purge to be 500 mL / min, the temperature of the secondary purge to be 55° C., and the time to be 2 h; after the secondary purge, take out the catalyst and dry it to obtain a second portion of palladium catalyst; The mixed liquid is a mixture of toluene and triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone, wherein the volume ratio of toluene to the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 100:0.9, and the molecular weight ratio of polycaprolactone to polyethylene glycol in the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 0.85:1; 8. Secondary mixing: uniformly mix all of the first portion of palladium catalyst obtained in the primary treatment step of step 6 and all of the second portion of palladium catalyst obtained in the secondary treatment step of step 7 to obtain a regenerated palladium catalyst.

[0016] Example 3 A method for regenerating a palladium catalyst for hydrogen peroxide, specifically: 1. Classification: The palladium catalyst particles to be regenerated are classified according to the particle size, and the palladium catalyst particles to be regenerated with a particle size greater than or equal to 2 mm are regarded as complete palladium catalyst particles, and the palladium catalyst particles to be regenerated with a particle size less than 2 mm are regarded as broken palladium catalyst particles; The carrier of the palladium catalyst particles to be regenerated is porous alumina, the original palladium content is 0.307wt%, the original particle size is 2mm, and the original specific surface area is 120m 2 / g, the original bulk density is 0.65g / mL, and the original pore volume is 0.60mL / g; 2. Ball milling: The crushed palladium catalyst particles are placed in a planetary ball mill and ball milled at room temperature. The grinding balls in the planetary ball mill are alumina grinding balls. The particle size of the alumina grinding balls is 6 mm. The ball-to-material ratio is 6:1. The ball milling speed is 150 rpm and the ball milling time is 10 min. After the ball milling is completed, the materials in the planetary ball mill are collected. After the alumina grinding balls are separated from the materials, the remaining materials are classified according to the particle size. The materials with a particle size of less than 100 μm are classified as small particle size materials, and the materials with a particle size of greater than or equal to 100 μm are classified as large particle size materials. 3. Primary mixing: add deionized water and aluminum chloride to the small particle size material, stir at 80°C at a stirring speed of 100 rpm for 30 min, add triblock copolymer P123, and continue stirring for 30 min to obtain a primary mixed solution; The dosage ratio of small particle size material, deionized water, aluminum chloride, and triblock copolymer P123 is 105 g:1.8 L:11 g:10 g; 4. Hydrothermal synthesis: After mixing the primary mixed solution, urea and polystyrene microspheres, stir at room temperature at a stirring speed of 100 rpm for 30 minutes, perform hydrothermal reaction at 160°C for 10 hours, take out the precipitate after centrifugation, wash the precipitate with water and dry it to obtain composite microspheres; The particle size of the polystyrene microspheres is 500 nm; The dosage ratio of the primary mixed liquid, urea, and polystyrene microspheres is 1.8L:25g:0.52g; 5. Molding: Add all the large-particle materials obtained in the ball milling step of step 2, all the composite microspheres obtained in the hydrothermal synthesis step of step 4, gum arabic, and deionized water into a mixer and mix them evenly, then press them into spheres with a particle size of 2 mm, and then calcine them at 450° C. for 2.5 hours in a nitrogen atmosphere to obtain a spherical catalyst; The mass ratio of the total mass of the large-size material and the composite microspheres to the mass ratio of gum arabic and deionized water is 1000:23:1200; 6. One-time treatment: put all the spherical catalysts obtained in the 5th step of the molding step into the constant temperature section of the fixed bed, fill the upper and lower parts with quartz sand, and then soak them with toluene, control the volume ratio of toluene to spherical catalyst used in the soaking to be 7:1, the soaking temperature is 60°C, the soaking time is 33h, and the toluene is released after the soaking. Use nitrogen to purge once, control the flow rate of nitrogen in the purge to 520mL / min, the purge temperature is 60°C, the time is 7h, and after the purge is completed, use water vapor to clean once, and control once The flow rate of water vapor during cleaning is 200 mL / h, the temperature is 110° C., and the time is 20 h. After the first cleaning, hot water is used for secondary cleaning. The flow rate of hot water in the secondary cleaning is controlled to be 130 mL / h, the temperature is 100° C., and the time is 9 h. After the second cleaning, a mixed gas of nitrogen and hydrogen is used for secondary purge. The flow rate of the mixed gas of nitrogen and hydrogen in the secondary purge is controlled to be 520 mL / min, the temperature of the secondary purge is 80° C., and the time is 2 h. After the second purge, the catalyst is taken out and dried to obtain the first portion of palladium catalyst; The volume ratio of nitrogen to hydrogen in the mixed gas of nitrogen and hydrogen is 5:1; 7. Secondary treatment: All the complete palladium catalyst particles obtained in the first step of the classification step are loaded into the constant temperature section of the fixed bed, filled with quartz sand on the top and bottom, and then soaked with the mixed solution, and the volume ratio of the mixed solution used in the soaking to the complete palladium catalyst particles is controlled to be 4:1, the soaking temperature is 60°C, and the soaking time is 33h. While soaking, nitrogen is passed into the mixed solution in the fixed bed for a purge, starting from the bottom of the fixed bed, and the flow rate of nitrogen in the purge is controlled to be 750mL / min. The purge is ended at the end of the soaking, and then Then use water vapor for a cleaning, control the flow rate of water vapor in the first cleaning to 200mL / h, the temperature to 110°C, and the time to 13h. After the first cleaning, use hot water for a second cleaning, control the flow rate of hot water in the second cleaning to 130mL / h, the temperature to 100°C, and the time to 6h. After the second cleaning, use nitrogen for a second purge, control the flow rate of nitrogen in the second purge to 520mL / min, the temperature of the second purge to 60°C, and the time to 2h. After the second purge, take out the catalyst and dry it to obtain a second portion of palladium catalyst; The mixed liquid is a mixture of toluene and triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone, wherein the volume ratio of toluene to the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 100:1, and the molecular weight ratio of polycaprolactone to polyethylene glycol in the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 0.85:1; 8. Secondary mixing: uniformly mix all of the first portion of palladium catalyst obtained in the primary treatment step of step 6 and all of the second portion of palladium catalyst obtained in the secondary treatment step of step 7 to obtain a regenerated palladium catalyst.

[0017] Comparative Example 1 This comparative example is a comparison of the regeneration method of Example 2. Specifically, based on the regeneration method of Example 2, the mixed liquid in the 7th step of the secondary treatment step is omitted, and deionized water is used for soaking and then nitrogen purging is performed. Specifically, the 7th step of the secondary treatment step is changed to: All the complete palladium catalyst particles obtained in the first step of the classification step are loaded into the constant temperature section of the fixed bed, filled with quartz sand above and below, and then soaked with deionized water, the volume ratio of deionized water used in the soaking to the spherical catalyst is controlled to be 3.9:1, the soaking temperature is 55°C, and the soaking time is 32h. After the soaking, nitrogen is used for a purge, and the flow rate of nitrogen in the purge is controlled to be 720mL / min. After the purge, water vapor is used for a cleaning, and the flow rate of water vapor in the cleaning is controlled to be 190mL / h, the temperature is 105°C, and the time is 12.5h. After the cleaning, hot water is used for a secondary cleaning, and the flow rate of hot water in the secondary cleaning is controlled to be 125mL / h, the temperature is 100°C, and the time is 5.5h. After the secondary cleaning, nitrogen is used for a secondary purge, and the flow rate of nitrogen in the secondary purge is controlled to be 500mL / min, the temperature of the secondary purge is 55°C, and the time is 2h. After the secondary purge, the catalyst is taken out and dried to obtain a second portion of palladium catalyst.

[0018] Performance Testing The palladium content, hydrogen efficiency and specific surface area of ​​the palladium catalysts after regeneration in Examples 1-3 and Comparative Example 1 were tested, and the test results are as follows:

[0019] It can be seen from the results of the performance test that the hydrogen efficiency and specific surface area of ​​the palladium catalyst after regeneration in Comparative Example 1 are lower than those of the palladium catalyst after regeneration in Example 2.

[0020] Unless otherwise specified, all percentages used in the present invention are by mass.

[0021] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for regenerating a palladium catalyst for hydrogen peroxide, characterized in that: include: Classification, ball milling, primary mixing, hydrothermal synthesis, molding, primary treatment, secondary treatment, secondary mixing; The classification is to classify the palladium catalyst particles to be regenerated according to the particle size to obtain complete palladium catalyst particles and broken palladium catalyst particles; The ball milling comprises ball milling the crushed palladium catalyst particles and classifying them according to particle size to obtain small particle size materials and large particle size materials; In the primary mixing, deionized water and aluminum chloride are added to the small particle size material, stirred once, and the triblock copolymer P123 is added, stirred twice to obtain a primary mixed solution; The hydrothermal synthesis comprises mixing the primary mixed solution, urea and polystyrene microspheres, stirring, hydrothermal reaction and post-treatment to obtain composite microspheres; The molding comprises mixing the large-particle material, the composite microspheres, gum arabic and deionized water, pressing them into a spherical body, and calcining them to obtain a spherical catalyst; The first treatment comprises soaking the spherical catalyst with toluene, then purging it with nitrogen, washing it with water vapor, washing it twice with hot water, purging it twice with a mixed gas of nitrogen and hydrogen, and drying it to obtain a first portion of palladium catalyst; The secondary treatment uses a mixed liquid to soak the complete palladium catalyst particles, and while soaking, nitrogen is introduced into the mixed liquid in the fixed bed for a purge, starting from the bottom of the fixed bed, and the purge ends at the end of soaking, and then water vapor is used for a cleaning, hot water is used for a second cleaning, nitrogen is used for a second purge, and drying is performed to obtain a second portion of palladium catalyst.

2. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein The classification includes classifying the palladium catalyst particles to be regenerated according to their particle size, classifying the palladium catalyst particles to be regenerated with a particle size greater than or equal to 2 mm as complete palladium catalyst particles, and classifying the palladium catalyst particles to be regenerated with a particle size less than 2 mm as broken palladium catalyst particles; In the classification, the carrier of the palladium catalyst particles to be regenerated is porous alumina, the original palladium content is 0.307wt%, the original particle size is 2mm, and the original specific surface area is 120m 2 / g, the original bulk density is 0.65g / mL, and the original pore volume is 0.60mL / g.

3. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein The ball milling comprises placing the crushed palladium catalyst particles into a planetary ball mill and performing ball milling at room temperature, collecting the material in the planetary ball mill after the ball milling is completed, separating the alumina grinding balls from the material, and classifying the remaining material according to the particle size, wherein the material with a particle size less than 100 μm is regarded as a small particle size material, and the material with a particle size greater than or equal to 100 μm is regarded as a large particle size material; In the ball milling, the grinding balls in the planetary ball mill are alumina grinding balls, the particle size of the alumina grinding balls is 6 mm, the ball-to-material ratio is 5-6:1, the ball milling speed is 130-150 rpm, and the ball milling time is 9-10 min.

4. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein In the primary mixing, the dosage ratio of the small particle size material, deionized water, aluminum chloride, and triblock copolymer P123 is 102-105 g: 1.7-1.8 L: 10-11 g: 9-10 g; The stirring temperature is 70-80℃ and the stirring time is 20-30min; The temperature of the secondary stirring is 70-80°C and the time is 20-30 minutes.

5. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein In the hydrothermal synthesis, the particle size of the polystyrene microspheres is 500 nm; The dosage ratio of the primary mixed liquid, urea, and polystyrene microspheres is 1.7-1.8L: 20-25g: 0.5-0.52g; The stirring temperature is room temperature and the time is 20-30min; The temperature of the hydrothermal reaction is 150-160°C and the time is 9-10h; The post-treatment comprises taking a precipitate after centrifugation, washing the precipitate with water and drying the precipitate.

6. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein In the molding, the mass ratio of the total mass of the large-particle material and the composite microspheres to the mass ratio of gum arabic and deionized water is 1000:20-23:1100-1200; The particle size of the spherical blank is 2 mm; The calcination is carried out in a nitrogen atmosphere, the calcination temperature is 400-450° C., and the calcination time is 2-2.5 hours.

7. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein In the primary treatment, the spherical catalyst is loaded into the constant temperature section of the fixed bed and filled with quartz sand above and below; The volume ratio of toluene to the spherical catalyst used in the soaking is 6-7:1, the soaking temperature is 50-60° C., and the soaking time is 30-33 hours; The flow rate of nitrogen in the primary purge is 480-520 mL / min, the temperature of the primary purge is 50-60° C., and the time is 6-7 h; The flow rate of water vapor in the first cleaning is 180-200 mL / h, the temperature is 100-110° C., and the time is 19-20 h; The flow rate of hot water in the secondary cleaning is 120-130 mL / h, the temperature is 100° C., and the time is 8-9 h; The flow rate of the mixed gas of nitrogen and hydrogen in the secondary purge is 480-520 mL / min, the temperature of the secondary purge is 70-80° C., and the time is 1.5-2 h; The volume ratio of nitrogen to hydrogen in the mixed gas of nitrogen and hydrogen is 4-5:

1.

8. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein In the secondary treatment, the complete palladium catalyst particles are loaded into the constant temperature section of the fixed bed and filled with quartz sand above and below; The volume ratio of the mixed solution used in the soaking to the complete palladium catalyst particles is 3.8-4:1, the soaking temperature is 50-60° C., and the soaking time is 30-33 hours; The flow rate of nitrogen in the primary purge is 700-750 mL / min; The flow rate of water vapor in the first cleaning is 180-200 mL / h, the temperature is 100-110° C., and the time is 12-13 h; The flow rate of hot water in the secondary cleaning is 120-130 mL / h, the temperature is 100° C., and the time is 5-6 h; The flow rate of nitrogen in the secondary purge is 480-520 mL / min, the temperature of the secondary purge is 50-60° C., and the time is 1.5-2 h.

9. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein The mixed liquid is a mixture of toluene and triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone, wherein the volume ratio of toluene to the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 100:0.9-1, and the molecular weight ratio of polycaprolactone to polyethylene glycol in the triblock copolymer polycaprolactone-polyethylene glycol-polycaprolactone is 0.85:

1.

10. The regeneration method of palladium catalyst for hydrogen peroxide according to claim 1, wherein The secondary mixing is to mix the first portion of the palladium catalyst and the second portion of the palladium catalyst evenly to obtain a regenerated palladium catalyst.

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