Rare-earth-based soil remediation catalyst as well as preparation method and application thereof

Abstract

The invention discloses a rare-earth-based soil remediation catalyst as well as a preparation method and application thereof. The catalyst takes a composite oxide of micron-sized aluminum oxide and titanium dioxide as a carrier, a nano-fiber composite oxide of cerium oxide and copper oxide as an active component and a nano-particle composite oxide of iron oxide and manganese dioxide as a cocatalyst; on the basis of the mass of the carrier, the mass percentage of the active component is 5-10%, and the mass percentage of the cocatalyst is 3-6%. The catalyst synthesized through the method has the advantages of being good in soil compatibility, high in catalytic efficiency and the like, and the target of low-energy-consumption remediation of organic pollutant soil can be achieved.

Description

Technical Field

[0001] This invention relates to a rare earth-based soil remediation catalyst, its preparation method, and its application, belonging to the field of soil pollution remediation. Background Technology

[0002] The overlap of historical sites from industries such as coking, chemicals, petrochemicals, pesticides, and dyeing with newly added contaminated sites has led to the long-term accumulation of high-risk organic pollutants such as polycyclic aromatic hydrocarbons (PAHs), chlorinated organic compounds (COPs), petroleum hydrocarbons, and persistent organic pollutants (POPs) in the soil. These pollutants are characterized by high concentrations, strong toxicity, and stable molecular structures, making bioremediation alone ineffective for decades. While traditional thermal desorption can volatilize and separate pollutants from the soil within hours, most existing devices rely on temperatures above 800°C, resulting in high energy consumption, difficulty in controlling secondary pollutants in the exhaust gas, and insufficient removal rates for high-boiling-point and high-halogen-content organic pollutants. Catalyst-assisted low-temperature thermal desorption technology, with its advantages of achieving efficient pollutant pyrolysis within the 250–550°C range and significantly reducing energy consumption, is of great significance in the field of organic-contaminated soil remediation.

[0003] Catalyst development is crucial for catalytic removal technologies. In recent years, researchers have made significant progress in the synthesis, modification, and application of soil remediation catalysts. Noble metal catalysts such as platinum, palladium, and rhodium have been extensively studied, exhibiting excellent catalytic activity in the oxidation and reduction reactions of organic pollutants. However, despite their high activity, the high cost of noble metal catalysts limits their large-scale application. Metal oxide catalysts such as titanium dioxide (TiO2) and manganese dioxide (MnO2) have shown good performance in the photocatalytic degradation and oxidation of soil organic pollutants, especially under ultraviolet light irradiation, where titanium dioxide exhibits strong photocatalytic activity. Furthermore, nanomaterials, due to their high specific surface area and unique catalytic properties, show great potential in soil pollution remediation. Nanocatalysts not only improve reaction efficiency but also enhance the adsorption and degradation capacity of pollutants. Therefore, developing low-cost, non-toxic, and highly efficient nano-type soil remediation catalysts, especially for treating complex and diverse organic pollutants, and improving the selectivity and durability of catalysts, is of great significance. Summary of the Invention

[0004] The purpose of this invention is to address the current status and existing problems of catalytic removal of organic pollutants in soil, and to propose a rare earth-based soil remediation catalyst, its preparation method, and its application.

[0005] A rare earth-based soil remediation catalyst is disclosed. The catalyst uses a composite oxide of micron-sized alumina and titanium dioxide as a support, a composite oxide of cerium oxide and copper oxide nanofibers as the active component, and a composite oxide of iron oxide and manganese dioxide nanoparticles as a co-catalyst. It is prepared using a combined method of ultrasonic atomization-freezing to bead formation, high-pressure hydrothermal vapor-phase encapsulation, pulsed voltage deposition oxidation, and ultrasonic-assisted confined precipitation. Based on the mass of the support, the mass percentage of the active component is 1-10%, the mass percentage of the co-catalyst is 1-10%, the mass ratio of alumina to titanium dioxide in the support is 1:(0.1-1), the mass ratio of cerium oxide to copper oxide in the active component is 1:(0.1-1), and the mass ratio of iron oxide to manganese dioxide in the co-catalyst is 1:(0.1-3).

[0006] In some preferred technologies: based on the carrier mass, the mass percentage of the active component is 5-10%, the mass percentage of the co-catalyst is 3-6%, the mass ratio of alumina to titanium dioxide in the carrier is 1:(0.1-0.2), the mass ratio of cerium oxide to copper oxide in the active component is 1:(0.3-0.6), and the mass ratio of iron oxide to manganese dioxide in the co-catalyst is 1:(0.5-2).

[0007] A method for preparing the above-mentioned catalyst, the method of which is as follows:

[0008] (1) Preparation of alumina by ultrasonic atomization and cryogenic bead formation

[0009] Aluminum salt and deionized water are mixed and placed in a constant temperature water bath for stirring and hydrolysis to form a sol. Then, polymethyl methacrylate microsphere solution and nitric acid solution are added. During the stirring process in the constant temperature water bath, a mixed sol is formed. The mixed sol is then atomized by ultrasonication to generate droplets and sprayed into a stainless steel beaker containing liquid nitrogen to form solid microspheres. The solid microspheres are then placed in a freeze dryer for freeze drying and finally calcined at high temperature to obtain micron-sized alumina powder.

[0010] (2) High-pressure hydrothermal vapor phase encapsulation of titanium dioxide nanoneedles

[0011] Weigh the micron-sized alumina powder obtained in step (1), mix it with urea solution and place it in a constant temperature water bath. Then add titanium salt, stir and pass carbon dioxide to react. After the reaction is completed, centrifuge and wash. Then mix the washed product with deionized water and hydrochloric acid solution and place it in a hydrothermal reactor. After high temperature hydrothermal reaction, filter and dry it and place it in a muffle furnace to calcine to obtain carrier powder.

[0012] (3) Pulse voltage deposition of oxidative loaded active components

[0013] Weigh out cerium salt, copper salt, deionized water, ethylene glycol and the carrier powder obtained in step (2) and mix them evenly to form a slurry electrolyte. Use a titanium mesh as the anode and a stainless steel reactor wall as the cathode. Apply a pulse voltage to perform electrochemical deposition. Then, collect the deposited product by centrifugation and place it in a quartz tube. Place the quartz tube in a tube atmosphere furnace. Use a microfluidic pump injector to pump deionized water into a mixing tank and introduce oxygen. Place the mixing tank in an oil bath. Then, introduce the mixture of oxygen and deionized water into the quartz tube and calcine it at high temperature to form a composite carrier powder loaded with active components.

[0014] (4) Preparation of catalysts by ultrasound-assisted confined precipitation

[0015] Weigh out iron salt, manganese salt and ethylene glycol to form a catalyst precursor solution. Then add the composite carrier powder loaded with active components obtained in step (3) to the catalyst precursor solution. After ultrasonic treatment, add oxalic acid ethanol solution dropwise and stir continuously. After the reaction is completed, filter and place the filtered product in a muffle furnace to calcine to form a catalyst.

[0016] In the above preparation method: the aluminum salt mentioned in step (1) is aluminum isopropoxide, the mass fraction of nitric acid solution is 5~15%, the particle size of polymethyl methacrylate microspheres is 200~400nm, the concentration of polymethyl methacrylate microsphere solution is 25~50mg / mL, the mass ratio of aluminum salt, deionized water, polymethyl methacrylate microsphere solution and nitric acid solution is 1:(40~80):(3~6):(1~3), the temperature of constant temperature water bath is 75~95℃, and the stirring hydrolysis time is 1~2h;

[0017] The frequency of ultrasonic atomization in step (1) is 1.5~2.0MHz; the temperature of freeze drying is -40~-50℃ and the time of freeze drying is 36~72h; the temperature of high-temperature calcination is 500~600℃ and the time of high-temperature calcination is 3~6h.

[0018] In the above preparation method: the mass ratio of deionized water to urea in the urea solution in step (2) is 1:(1.6~1.8), the titanium salt is titanium oxysulfate, the mass ratio of micronized alumina powder to urea solution is 1:(40~60), the temperature of the constant temperature water bath is 60~80℃, the rate of carbon dioxide introduction is 60~120mL / min, and the reaction time is 2~4h.

[0019] In the above preparation method: the mass fraction of the hydrochloric acid solution in step (2) is 10~20%, and the mass ratio of the centrifuged washing product, deionized water and hydrochloric acid solution is 1:(30~60):(0.5~1.0); the temperature of the high-temperature hydrothermal reaction is 160~180℃, and the time of the high-temperature hydrothermal reaction is 4~8h; the drying temperature is 80~100℃, and the drying time is 6~12h; the calcination temperature is 500~700℃, and the calcination time is 1~2h.

[0020] In the above preparation method: the cerium salt mentioned in step (3) is cerium nitrate hexahydrate or cerium chloride, the copper salt is copper nitrate or copper chloride, and the mass ratio of cerium salt, deionized water and ethylene glycol is 1:(150~300):(30~50); the size of the titanium mesh is (2~4)cm×(2~4)cm, and the specification of the titanium mesh is 100~150 mesh; the pulse voltage is 15~20V, the frequency of the pulse voltage is 100Hz, the duty cycle of the pulse voltage is 50~70%, and the electrochemical deposition time is 30~60min.

[0021] In the above preparation method: the oxygen introduction rate in step (3) is 100~200mL / min, the deionized water pumping rate is 1~2mL / min; the oil bath temperature is 120~150℃; the high-temperature calcination temperature is 500~600℃, and the high-temperature calcination time is 3~6h.

[0022] In the above preparation method: the iron salt mentioned in step (4) is ferric nitrate nonahydrate or ferric chloride hexahydrate, the manganese salt is manganese nitrate hexahydrate or manganese chloride, the mass fraction of oxalic acid ethanol solution is 10~20%, and the mass ratio of iron salt, ethylene glycol and oxalic acid ethanol solution is 1:(100~200):(20~40); the ultrasonic treatment power is 200~300W, the ultrasonic treatment time is 30~60min; the continuous stirring time is 2~4h; the calcination temperature is 500~600℃, and the calcination time is 2~4h.

[0023] In the technical solution of this invention, the application of the catalyst in the catalytic removal of organic pollutants in the field of soil remediation is preferred, wherein the organic pollutants specifically refer to chlorobenzene and o-xylene.

[0024] The thermal desorption experimental conditions and results of the present invention: 50g of soil containing 5% chlorobenzene or 5% o-xylene was loaded into the catalyst performance evaluation reaction device. The inner diameter of the quartz tube in the evaluation reaction device was 10mm. The soil heating temperature and hot air temperature were 120°C. The amount of catalyst used was 5g. After thermal desorption at 120°C for 20min, the desorption effect of chlorobenzene and o-xylene could reach 100%.

[0025] Beneficial effects:

[0026] (1) In order to avoid the agglomeration of alumina particles in conventional preparation methods and the random powder caused by traditional grinding methods, this invention uses ultrasonic atomization to accurately generate monodisperse micron-sized droplets. After freezing and fixing the morphology, micron-sized alumina powder is finally obtained. In order to improve the porosity of the carrier, this invention uses PMMA calcination to form mesopores and ice crystal sublimation to leave macropores, thereby forming a macropore-mesopore interconnected structure, which can effectively reduce the mass transfer resistance of organic pollutant molecules and facilitate the diffusion of reaction molecules and products inside the catalyst channels.

[0027] (2) In order to increase the concentration of hydroxyl groups on the surface of alumina and the formation of nanofibers by the subsequent active components, this invention uses titanium oxysulfate as a nucleation inducing agent and carrier precursor. By introducing carbon dioxide gas into the mixed solution to form an acidic environment, the local pH change environment formed by the decomposition of urea and the dissolution of carbon dioxide is promoted, thereby heterogeneously precipitating an amorphous composite thin layer of titanium carbonate and titanium hydroxide on the surface of alumina. Then, hydrochloric acid is used as a morphology control agent in the high-temperature hydrothermal reaction to promote the recrystallization of the composite thin layer on the surface of alumina into nanoneedles and increase the concentration of hydroxyl groups on the surface of alumina and the formation of Ti-O-Al bonds between alumina and titanium dioxide.

[0028] (3) In order to enable the active components to form a nanofiber structure, the present invention utilizes pulsed electrochemical deposition to selectively and rapidly reduce cerium ions and copper ions and deposit them on the surface of titanium dioxide nanoneedles. The deposited products are then calcined in a high-humidity environment. The difference in oxidation kinetics between cerium and copper is used to enable the cerium and copper precursors to grow anisotropically, ultimately forming cerium oxide and copper oxide composite oxide nanofibers assembled from nanoparticles.

[0029] (4) In order for the composite oxides of iron oxide and manganese oxide to be uniformly loaded on the carrier without agglomeration, the present invention uses ultrasonic treatment to allow the precursor solution to penetrate into the gaps between the nanofibers and the surface of the carrier. Then, the coordination of oxalic acid with iron ions and manganese ions is used to achieve confined precipitation, thereby avoiding excessive growth of the co-catalyst nanospheres. Finally, high-temperature calcination and pyrolysis are used to retain the morphology of the nanospheres while forming the composite oxide interface.

[0030] (5) In this invention, the composite oxide of cerium oxide and copper oxide is prepared into a nanofiber structure. The nanofiber has a high specific surface area and can avoid the close packing of nanoparticles, thereby exposing more active sites. At the same time, the one-dimensional structure of the nanofiber can provide a continuous path for electron transport and reduce the interfacial resistance, which is conducive to the rapid transfer of electrons in the catalytic reaction.

[0031] (6) In this invention, the composite oxide of iron oxide and manganese oxide is prepared into a nanosphere structure. By utilizing its distribution in the gaps and surface of the nanofibers, the surface modification of the active component is achieved, avoiding the blockage of the mass transfer channel. It can also form a new interface with the nanofibers. The interface is the most effective region for electronic interaction, which can promote the electron transfer between the active component and the cocatalyst, thereby modulating the electronic state of the active center and enhancing the intrinsic activity of the active site.

[0032] Therefore, the catalyst prepared by this invention not only has excellent low-temperature catalytic removal performance for chlorobenzene and o-xylene, but also good soil compatibility. Moreover, the catalyst components are environmentally friendly, the preparation process is simple, and it has strong application and promotion value. Attached Figure Description

[0033] Figure 1 SEM image of the catalyst prepared in Example 1;

[0034] Figure 2 The graph shows the chlorobenzene removal rate of the catalysts prepared in Examples 1-2;

[0035] Figure 3 The graph shows the o-xylene removal rate of the catalysts prepared in Examples 1-2. Detailed Implementation

[0036] The present invention will be further described below with reference to the embodiments. The embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0037] Example 1

[0038] (1) Preparation of alumina by ultrasonic atomization and cryogenic bead formation

[0039] 40.063 g of aluminum isopropoxide and 1602.520 g of deionized water were weighed, mixed, and placed in a 75°C constant temperature water bath for 2 hours to hydrolyze and form a sol. Then, 120.189 g of polymethyl methacrylate microsphere solution (the particle size of the polymethyl methacrylate microspheres was 200 nm, and the concentration of the polymethyl methacrylate microsphere solution was 25 mg / mL) and 40.063 g of 5% nitric acid solution were added. During the stirring in a 75°C constant temperature water bath for 2 hours, a mixed sol was formed. The mixed sol was then ultrasonically atomized (the frequency of ultrasonic atomization was 1.5 MHz) to generate droplets, which were sprayed into a stainless steel beaker containing 7211.340 g of liquid nitrogen to form solid microspheres. The solid microspheres were then placed in a freeze dryer and freeze-dried at -40°C for 72 hours. Finally, they were calcined at 500°C for 6 hours to obtain micron-sized alumina powder.

[0040] (2) High-pressure hydrothermal vapor phase encapsulation of titanium dioxide nanoneedles

[0041] Weigh 10.000g of the micron-sized alumina powder obtained in step (1) and mix it with 400g of urea solution (the urea solution is formed by mixing 153.846g of deionized water and 246.154g of urea) and place it in a constant temperature water bath at 60℃. Then add 2.003g of titanium oxysulfate, stir and introduce carbon dioxide (the rate of introducing carbon dioxide is 60mL / min) and react for 4h. After the reaction is completed, centrifuge and wash with deionized water. Then mix 10.000g of the centrifuged and washed product with 300.000g of deionized water and 5g of 10% hydrochloric acid solution and place it in a hydrothermal reactor. After hydrothermal reaction at 160℃ for 8h, filter it, dry it at 80℃ for 12h and calcine it in a muffle furnace at 500℃ for 2h to obtain the carrier powder.

[0042] (3) Pulse voltage deposition of oxidative loaded active components

[0043] Weigh out 0.484g of cerium nitrate hexahydrate, 0.137g of copper nitrate, 72.600g of deionized water, 14.520g of ethylene glycol, and 5.000g of the carrier powder obtained in step (2). Mix them evenly to form a slurry electrolyte. Use a titanium mesh (2cm×2cm, 100 mesh) as the anode and a stainless steel reactor wall as the cathode. Apply a 15V pulse voltage for electrochemical deposition for 60min (pulse voltage frequency 100Hz, pulse voltage duty cycle 50%). The deposited product was then collected by centrifugation and placed in a quartz tube. The quartz tube was placed in a tubular atmosphere furnace, and deionized water was pumped into a mixing tank using a microfluidic pump injector (the pumping rate of deionized water was 1 mL / min) and oxygen was introduced (the oxygen introduction rate was 100 mL / min). The mixing tank was placed in an oil bath (the oil bath temperature was 120℃). Then, the mixture of oxygen and deionized water was introduced into the quartz tube and calcined at 500℃ for 6 hours to form a composite carrier powder loaded with active components.

[0044] (4) Preparation of catalysts by ultrasound-assisted confined precipitation

[0045] Weigh 0.506g of ferric nitrate nonahydrate, 0.165g of manganese nitrate hexahydrate, and 50.600g of ethylene glycol and mix them to form a catalyst precursor solution. Then, add the composite support powder loaded with active components obtained in step (3) to the catalyst precursor solution. After ultrasonic treatment at 200W for 60min, add 10.120g of 10% oxalic acid ethanol solution and stir continuously for 4h. After the reaction is completed, filter and place the filtered product in a muffle furnace and calcine at 500℃ for 4h to form a catalyst (based on the mass of the support, the mass percentage of the active component is 5%, the mass percentage of the catalyst is 3%, the mass ratio of alumina to titanium dioxide in the support is 1:0.1, the mass ratio of cerium oxide to copper oxide in the active component is 1:0.3, the mass ratio of iron oxide to manganese dioxide in the catalyst is 1:0.5, and the SEM image of the catalyst is shown below). Figure 1 (as shown)

[0046] (5) Catalytic activity test

[0047] Take 50g of soil containing 5% chlorobenzene or 5% o-xylene and put it into the catalyst performance evaluation reaction device. The inner diameter of the quartz tube in the evaluation reaction device is 10mm, the soil heating temperature and hot air temperature are 120℃, the amount of catalyst used is 5g, and the desorption effect of chlorobenzene and o-xylene can reach 100% after thermal desorption at 120°C for 20min.

[0048] Example 2

[0049] (1) Preparation of alumina by ultrasonic atomization and cryogenic bead formation

[0050] Weigh 40.063g of aluminum isopropoxide and 3205.040g of deionized water, mix them, and place them in a 95℃ constant temperature water bath for 1 hour to stir and hydrolyze to form a sol. Then, add 240.378g of polymethyl methacrylate microsphere solution (the particle size of polymethyl methacrylate microspheres is 400nm, and the concentration of polymethyl methacrylate microsphere solution is 50mg / mL) and 120.189g of 15% nitric acid solution. During the stirring in a 95℃ constant temperature water bath for 1 hour, a mixed sol is formed. The mixed sol is then ultrasonically atomized (the frequency of ultrasonic atomization is 2.0MHz) to generate droplets, which are sprayed into a stainless steel beaker containing 21634.020g of liquid nitrogen to form solid microspheres. The solid microspheres are then placed in a freeze dryer and freeze-dried at -50℃ for 36 hours. Finally, they are calcined at 600℃ for 3 hours to obtain micron-sized alumina powder.

[0051] (2) High-pressure hydrothermal vapor phase encapsulation of titanium dioxide nanoneedles

[0052] Weigh 10.000g of the micron-sized alumina powder obtained in step (1) and mix it with 600g of urea solution (the urea solution is formed by mixing 214.286g of deionized water and 385.714g of urea) and place it in a constant temperature water bath at 80℃. Then add 4.006g of titanium oxysulfate, stir and introduce carbon dioxide (the rate of introducing carbon dioxide is 120mL / min) and react for 2h. After the reaction is completed, centrifuge and wash with deionized water. Then mix 10.000g of the centrifuged and washed product with 600.000g of deionized water and 10g of 20% hydrochloric acid solution and place it in a hydrothermal reactor. After hydrothermal reaction at 180℃ for 4h, filter it, dry it at 100℃ for 6h and calcine it in a muffle furnace at 700℃ for 1h to obtain the carrier powder.

[0053] (3) Pulse voltage deposition of oxidative loaded active components

[0054] Weigh out 0.448g of cerium chloride, 0.316g of copper chloride, 134.400g of deionized water, 22.400g of ethylene glycol, and 5.000g of the carrier powder obtained in step (2). Mix them evenly to form a slurry electrolyte. Use a titanium mesh (4cm×4cm, 150 mesh) as the anode and a stainless steel reactor wall as the cathode. Apply a 20V pulse voltage for electrochemical deposition for 30 minutes (pulse voltage frequency 100Hz, pulse voltage duty cycle 70%). The deposited product was then collected by centrifugation and placed in a quartz tube. The quartz tube was placed in a tubular atmosphere furnace, and deionized water was pumped into a mixing tank using a microfluidic pump injector (the pumping rate of deionized water was 2 mL / min), while oxygen was introduced (the oxygen introduction rate was 200 mL / min). The mixing tank was placed in an oil bath (the oil bath temperature was 150℃). Then, the mixture of oxygen and deionized water was introduced into the quartz tube and calcined at 600℃ for 3 hours to form a composite carrier powder loaded with active components.

[0055] (4) Preparation of catalysts by ultrasound-assisted confined precipitation

[0056] Weigh 0.339g of ferric chloride hexahydrate, 0.289g of manganese chloride, and 67.800g of ethylene glycol to form a catalyst precursor solution. Then, add the composite support powder loaded with active components obtained in step (3) to the catalyst precursor solution. After ultrasonic treatment at 300W for 30min, add 13.560g of 20% oxalic acid ethanol solution and stir continuously for 2h. After the reaction is completed, filter and place the filtered product in a muffle furnace and calcine at 600℃ for 2h to form a catalyst (based on the mass of the support, the mass percentage of the active component is 10%, the mass percentage of the catalyst is 6%, the mass ratio of alumina to titanium dioxide in the support is 1:0.2, the mass ratio of cerium oxide to copper oxide in the active component is 1:0.6, and the mass ratio of ferric oxide to manganese dioxide in the catalyst is 1:2).

[0057] (5) Catalytic activity test

[0058] Take 50g of soil containing 5% chlorobenzene or 5% o-xylene and put it into the catalyst performance evaluation reaction device. The inner diameter of the quartz tube in the evaluation reaction device is 10mm, the soil heating temperature and hot air temperature are 120℃, the amount of catalyst used is 5g, and the desorption effect of chlorobenzene and o-xylene can reach 100% after thermal desorption at 120°C for 20min.

Claims

1. A rare earth-based soil remediation catalyst, characterized in that: The catalyst is prepared using a composite oxide of micron-sized alumina and titanium dioxide as a support, a composite oxide of cerium oxide and copper oxide nanofibers as the active component, and a composite oxide of iron oxide and manganese dioxide nanoparticles as a co-catalyst. It is prepared by a combined method of ultrasonic atomization freezing into beads, high-pressure hydrothermal vapor phase encapsulation, pulsed voltage deposition oxidation, and ultrasonic-assisted confined precipitation. The mass percentage of the active component and the co-catalyst are 1-10% based on the mass of the support. The mass ratio of alumina to titanium dioxide in the support is 1:(0.1-1), the mass ratio of cerium oxide to copper oxide in the active component is 1:(0.1-1), and the mass ratio of iron oxide to manganese dioxide in the co-catalyst is 1:(0.1-3).

2. The rare earth-based soil remediation catalyst according to claim 1, characterized in that: Based on the carrier mass, the active component has a mass percentage of 5-10%, the co-catalyst has a mass percentage of 3-6%, the mass ratio of alumina to titanium dioxide in the carrier is 1:(0.1-0.2), the mass ratio of cerium oxide to copper oxide in the active component is 1:(0.3-0.6), and the mass ratio of iron oxide to manganese dioxide in the co-catalyst is 1:(0.5-2).

3. A method for preparing the catalyst according to claim 1 or 2, characterized in that: The catalyst is prepared as follows: (1) Preparation of alumina by ultrasonic atomization and cryogenic bead formation Aluminum salt and deionized water are mixed and placed in a constant temperature water bath for stirring and hydrolysis to form a sol. Then, polymethyl methacrylate microsphere solution and nitric acid solution are added. During the stirring process in the constant temperature water bath, a mixed sol is formed. The mixed sol is then atomized by ultrasonication to generate droplets and sprayed into a stainless steel beaker containing liquid nitrogen to form solid microspheres. The solid microspheres are then placed in a freeze dryer for freeze drying and finally calcined at high temperature to obtain micron-sized alumina powder. (2) High-pressure hydrothermal vapor phase encapsulation of titanium dioxide nanoneedles Weigh the micron-sized alumina powder obtained in step (1), mix it with urea solution and place it in a constant temperature water bath. Then add titanium salt, stir and pass carbon dioxide to react. After the reaction is completed, centrifuge and wash. Then mix the washed product with deionized water and hydrochloric acid solution and place it in a hydrothermal reactor. After high temperature hydrothermal reaction, filter and dry it and place it in a muffle furnace to calcine to obtain carrier powder. (3) Pulse voltage deposition of oxidative loaded active components Weigh out cerium salt, copper salt, deionized water, ethylene glycol and the carrier powder obtained in step (2) and mix them evenly to form a slurry electrolyte. Use a titanium mesh as the anode and a stainless steel reactor wall as the cathode. Apply a pulse voltage to perform electrochemical deposition. Then, collect the deposited product by centrifugation and place it in a quartz tube. Place the quartz tube in a tube atmosphere furnace. Use a microfluidic pump injector to pump deionized water into a mixing tank and introduce oxygen. Place the mixing tank in an oil bath. Then, introduce the mixture of oxygen and deionized water into the quartz tube and calcine it at high temperature to form a composite carrier powder loaded with active components. (4) Preparation of catalysts by ultrasound-assisted confined precipitation Weigh out iron salt, manganese salt and ethylene glycol to form a catalyst precursor solution. Then add the composite carrier powder loaded with active components obtained in step (3) to the catalyst precursor solution. After ultrasonic treatment, add oxalic acid ethanol solution dropwise and stir continuously. After the reaction is completed, filter and place the filtered product in a muffle furnace to calcine to form a catalyst.

4. The preparation method according to claim 1, characterized in that: The aluminum salt mentioned in step (1) is aluminum isopropoxide, the mass fraction of nitric acid solution is 5~15%, the particle size of polymethyl methacrylate microspheres is 200~400nm, the concentration of polymethyl methacrylate microsphere solution is 25~50mg / mL, the mass ratio of aluminum salt, deionized water, polymethyl methacrylate microsphere solution and nitric acid solution is 1:(40~80):(3~6):(1~3), the temperature of constant temperature water bath is 75~95℃, and the stirring hydrolysis time is 1~2h; The frequency of ultrasonic atomization in step (1) is 1.5~2.0MHz; the temperature of freeze drying is -40~-50℃ and the time of freeze drying is 36~72h; the temperature of high-temperature calcination is 500~600℃ and the time of high-temperature calcination is 3~6h.

5. The preparation method according to claim 1, characterized in that: In step (2), the mass ratio of deionized water to urea in the urea solution is 1:(1.6~1.8), the titanium salt is titanium oxysulfate, the mass ratio of micronized alumina powder to urea solution is 1:(40~60), the temperature of the constant temperature water bath is 60~80℃, the rate of carbon dioxide introduction is 60~120mL / min, and the reaction time is 2~4h.

6. The preparation method according to claim 2, characterized in that: The mass fraction of the hydrochloric acid solution mentioned in step (2) is 10~20%, and the mass ratio of the centrifuged washing product, deionized water and hydrochloric acid solution is 1:(30~60):(0.5~1.0); the temperature of the high-temperature hydrothermal reaction is 160~180℃, and the time of the high-temperature hydrothermal reaction is 4~8h; the drying temperature is 80~100℃, and the drying time is 6~12h; the calcination temperature is 500~700℃, and the calcination time is 1~2h.

7. The preparation method according to claim 2, characterized in that: The cerium salt mentioned in step (3) is cerium nitrate hexahydrate or cerium chloride, and the copper salt is copper nitrate or copper chloride. The mass ratio of cerium salt, deionized water and ethylene glycol is 1:(150~300):(30~50). The size of the titanium mesh is (2~4)cm×(2~4)cm, and the specification of the titanium mesh is 100~150 mesh. The pulse voltage is 15~20V, the frequency of the pulse voltage is 100Hz, the duty cycle of the pulse voltage is 50~70%, and the electrochemical deposition time is 30~60min.

8. The preparation method according to claim 2, characterized in that: In step (3), the oxygen introduction rate is 100-200 mL / min, the deionized water pumping rate is 1-2 mL / min, the oil bath temperature is 120-150℃, the high-temperature calcination temperature is 500-600℃, and the high-temperature calcination time is 3-6 h.

9. The preparation method according to claim 2, characterized in that: The iron salt mentioned in step (4) is ferric nitrate nonahydrate or ferric chloride hexahydrate, the manganese salt is manganese nitrate hexahydrate or manganese chloride, the mass fraction of oxalic acid ethanol solution is 10~20%, and the mass ratio of iron salt, ethylene glycol and oxalic acid ethanol solution is 1:(100~200):(20~40); the ultrasonic treatment power is 200~300W, the ultrasonic treatment time is 30~60min; the continuous stirring time is 2~4h; the calcination temperature is 500~600℃, and the calcination time is 2~4h.

10. The application of the catalyst of claim 1 in the catalytic removal of organic pollutants in the field of soil remediation, preferably, the organic pollutants specifically refer to chlorobenzene and o-xylene.

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