Networked soil thermal desorption catalyst, preparation method and application thereof

Abstract

The application discloses a network soil thermal desorption catalyst, a preparation method and application thereof, and belongs to the field of environmental protection. The catalyst takes an iron net as a carrier and takes manganese-cobalt composite metal sulfide as an active component. The mass content of the active component is 3-6% based on the mass of the carrier. The scheme is characterized in that the iron net is subjected to oxidation pretreatment, so that an iron trioxide oxidation layer is formed on the surface; then the iron net is immersed in an active component solution to perform electrochemical deposition loading; finally, the finished catalyst is formed through special atmosphere calcination. The catalyst is environment-friendly, can efficiently induce the thermal desorption of organic pollutants in soil, and can realize 100% removal of o-xylene at 120 DEG C. Meanwhile, the catalyst is convenient to recycle, has higher economic benefits and wide market application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method and application of a network-shaped soil thermal desorption catalyst, belonging to the field of environmental protection catalytic materials and soil remediation. BACKGROUND

[0002] With the adjustment of industrial structure and the development of urbanization, a large number of chemical enterprises have migrated to the north and northwest. The original factory sites are usually heavily polluted, and some highly toxic organic pollutants can accumulate in the soil, causing long-term threats. For example, the pollution of soil caused by petroleum hydrocarbons, polycyclic aromatic hydrocarbons, organophosphorus pesticides, and polychlorinated biphenyls, nitrosamines has the characteristics of accumulation, concealment, dynamics and irreversibility. Most of the organic pollutants have the characteristics of persistence, semi-volatility, biological enrichment and high toxicity, which pose a serious threat to human health and the ecological environment.

[0003] For the remediation of organic contaminated soil, extensive research has been conducted in recent years. Thermal desorption remediation technology has been widely applied due to its high treatment efficiency, short remediation period, and wide application range. It can be used to treat various organic pollutants such as nitrobenzene, polybrominated biphenyl ether, chlorobenzene, and polycyclic aromatic hydrocarbons. However, due to the high boiling point of most organic pollutants and their uneven distribution in the soil, a large amount of heat energy is consumed during thermal treatment. Studies have shown that the addition of an appropriate amount of thermal desorption catalyst can effectively reduce the desorption temperature and energy consumption. For example, patent CN115254131B discloses a solid heat carrier organic contaminated soil thermal desorption catalyst and its preparation method. Porous hollow alumina spheres are prepared as carriers using 3D printing technology. The finished catalyst is obtained by impregnating the active component copper-nickel-vanadium solution and calcination treatment, which can completely remove benzene[A] anthracene at 150℃. Patent CN116713308A discloses a method for soil catalytic thermal desorption of organic pollutants based on solvent induction and its application. The method uses refined diatomite as a carrier and copper-cerium-manganese composite oxides as an active component, which is synthesized by a hydrothermal method. It can completely regenerate the contaminated soil containing trichlorobenzene and dichlorophenol at 150-190℃. For example, CN113877597B discloses an organic contaminated soil thermal desorption single-atom catalyst and its preparation method. Alumina is used as a carrier, triethanolamine is used as an anchor agent, and cerium-manganese-iron metal oxides are used as an active component, which can significantly reduce the desorption temperature of benzene[A] anthracene. Most of the soil thermal desorption catalysts developed at present are in the form of particles or powders, which are difficult to recover, resulting in an increase in cost. At the same time, the metal elements in the catalyst may cause secondary pollution of the soil. Therefore, it is necessary to develop a catalyst with high thermal desorption efficiency and easy recovery. SUMMARY

[0004] The purpose of the present application is to solve the problems of high energy consumption and difficult catalyst recovery in the thermal desorption treatment of contaminated soil, and to propose a preparation method and application of a network-shaped soil thermal desorption catalyst.

[0005] The object of the present application can be achieved by the following technical solutions: a preparation method and application of a networked soil thermal desorption catalyst, which takes a ferrous net as a carrier and a manganese-cobalt composite metal sulfide as an active component. The method first pretreats the ferrous net to form a ferric oxide layer on the surface, thereby increasing the surface area and roughness of the carrier and facilitating the deposition of the active component. Then, a mixed solution of active component precursors and electrolyte is prepared, and the carrier is immersed in the solution as a cathode for electrochemical deposition. Manganese and cobalt will grow in the form of single elements on the surface of the ferrous net, and at the same time, the ferric oxide layer on the surface of the ferrous net will be reduced to elemental iron, thereby forming a small amount of manganese-cobalt-iron alloy doped with iron. In order to accelerate the electrochemical deposition rate, a precipitation aid should also be added to the mixed solution. Finally, the ferrous net is subjected to three-stage calcination in an atmosphere furnace. The first stage is to solidify the active component and convert the active elements from single elements to oxides, which facilitates the subsequent conversion to sulfides. The second stage is to convert the active elements to sulfides. The third stage adjusts the surface functional groups of the catalyst by calcining in a water vapor-rich environment to increase the content of surface hydroxyl groups.

[0006] A networked soil thermal desorption catalyst, which takes a manganese-cobalt composite metal sulfide as an active component and a ferrous net as a carrier. The mass content of the active component is 1-12% based on the mass of the carrier. The mass ratio of manganese sulfide to cobalt sulfide is 1-15:1-15 based on the mass of the active component.

[0007] In some more preferred technical solutions, the mass content of the active component is 1-10% based on the mass of the carrier. The mass ratio of manganese sulfide to cobalt sulfide is 1-10:1-10 based on the mass of the active component.

[0008] A preparation method of the above-mentioned networked soil thermal desorption catalyst, which is as follows:

[0009] (1) Carrier pretreatment: immerse the ferrous net in a sodium chloride aqueous solution to form a ferric oxide layer on the surface, then wash to remove residual sodium chloride, and dry for use;

[0010] (2) Active component deposition: prepare a mixed solution of active component, electrolyte, and precipitation aid, immerse the treated ferrous net in the mixed solution, and perform electrochemical deposition;

[0011] (3) Calcination treatment: place the dried ferrous net in an atmosphere furnace for three-stage calcination to obtain the finished catalyst. The first stage is calcination in an air or oxygen atmosphere, the second stage is calcination in a hydrogen sulfide or sulfur dioxide atmosphere, and the third stage is calcination in a water vapor atmosphere.

[0012] In the preparation method, the iron mesh in step (1) is cast iron, the diameter of the iron wire is 0.8-1.2 mm, and the aperture is 2-5 mesh; the concentration of the sodium chloride aqueous solution is 0.05-0.1 M, and the immersion time is 120-168 h.

[0013] In the preparation method, the active component precursor in step (2) is a chloride salt, nitrate salt or sulfate salt of manganese and cobalt; the electrolyte in the electrochemical deposition is ammonium chloride or ammonium nitrate, and the concentration of the electrolyte is 0.3-0.5 mol / L; the precipitation aid is o-benzoyl sulfimide, and the concentration of the precipitation aid is 0.02-0.04 g / L.

[0014] In the preparation method, the treated iron mesh in step (2) is used as a cathode, and a platinum sheet electrode is used as an anode; the distance between the anode and the cathode is 2-5 cm, the current is controlled by a direct current power supply, the current size is 1-3 A / cm 3 , and the deposition time is 1-3 h.

[0015] In the preparation method, the first-stage roasting in step (3) is carried out in an air atmosphere or an oxygen atmosphere, the gas inlet rate of the atmosphere is 30-50 ml / min, the roasting temperature is 500-600 DEG C, and the roasting time is 30-60 min; the second-stage roasting is carried out in a hydrogen sulfide or sulfur dioxide atmosphere, nitrogen is used as a carrier gas, the concentration of the hydrogen sulfide or sulfur dioxide is 500-1000 ppm, the gas inlet rate of the atmosphere is 30-50 ml / min, the roasting temperature is 800-1000 DEG C, and the roasting time is 4-6 h; the third-stage roasting is carried out in a water vapor atmosphere, nitrogen is used as a carrier gas, the deionized water inlet rate is 3-5 ml / min, the nitrogen inlet rate is 30-50 ml / min, the roasting temperature is 300-400 DEG C, and the roasting time is 30-60 min.

[0016] In the technical scheme, the catalyst is applied in the field of soil thermal desorption, and further, the soil is laid on the surface of the catalyst, and the distance between every two layers of the catalyst is 5-15 mm.

[0017] Beneficial effects:

[0018] The application discloses a preparation method and application of a network soil thermal desorption catalyst, and the catalyst takes an iron net as a carrier, takes manganese-cobalt composite metal sulfide as an active component, and loads the active component by using an electrochemical deposition method. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Efficiency diagram for o-xylene removal. DETAILED DESCRIPTION

[0020] The application will be further described through examples. The examples are implemented on the premise of the technical scheme of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0021] In the following examples, the experimental methods are all conventional methods in the field unless otherwise specified, and experimental devices and experimental raw materials can be commercially available unless otherwise specified.

[0022]

[0023]

[0024] Example 1

[0025] Cut 50 g of iron mesh (pig iron material, 2 mesh in diameter, iron wire diameter 0.8 mm, provided as a screen) and immerse it in a 0.1 M NaCl solution for 132 h to form a layer of Fe203on the surface of the iron wire. After removal, clean and dry the iron mesh for use. Weigh 4.9490 g of Mn(NO3)2·6H2O and 4.7972 g of Co(NO3)2·6H2O, dissolve them in 500 g of deionized water to prepare a mixed solution, and then dissolve 8.0250 g of NH4Cl and 0.01 g of o-benzoyl sulfonamide in the mixed solution to prepare an electrolyte (the concentration of NH4Cl is 0.3 M, and the concentration of o-benzoyl sulfonamide is 0.02 g / L). The iron mesh is used as the cathode, and the platinum sheet electrode is used as the anode, both of which are immersed in the electrolyte, and the distance between them is controlled to be 4 cm. Then, a direct current is applied by an electrochemical workstation, and the current is maintained at 3 A / cm2 3 Electrochemical deposition is performed for 2 h. After removal, clean and dry the iron mesh for use. The dried iron mesh is transferred to an atmosphere furnace for three-stage calcination treatment. The first stage of calcination is performed at 600°C for 45 min with a continuous air flow of 30 ml / min. The second stage of calcination is performed at 800°C for 5 h with a continuous SO2 gas flow of 50 ml / min (SO2 concentration: 800 ppm, carrier gas: N2). The third stage of calcination is performed at 400°C for 60 min under water vapor-rich conditions, with deionized water being added to the furnace at a rate of 3 ml / min by a micro-pump injector, and nitrogen gas being continuously introduced at a rate of 30 ml / min during the process. The final product, a network-like soil thermal desorption catalyst, is obtained.

[0026] Catalyst performance evaluation: The soil is completely dried to exclude water interference, and then o-xylene is mixed with the soil to simulate a contaminated soil (o-xylene content: 5%). The network-like soil thermal desorption catalyst is cut into a circular piece with a diameter of 10 cm for use. The reactor is a quartz tube with a diameter of 10 cm, and 500 g of contaminated soil containing 5% o-xylene is weighed and placed in the quartz tube, with a layer of catalyst circular piece being placed every 10 mm. The soil temperature and hot air temperature are controlled at 100°C, and the reaction is performed for 60 min, with the remaining mass being recorded every 10 min.

[0027] Example 2

[0028] Cut 50 g of iron mesh (pig iron material, 3 mesh in diameter, iron wire diameter 1.0 mm, provided as a screen) and immerse it in a 0.08 M NaCl solution for 144 h to form a layer of Fe203on the surface of the iron wire. After removal, clean and dry the iron mesh for use. Dissolve 3.4122 g of MnCl2-4H2O and 3.0890 g of CoSO4-7H2O in 400 g of deionized water to prepare a mixed solution, and then dissolve 16.0000 g of NH4NO3 and 0.012 g of o-benzoyl sulfimide in the mixed solution to prepare an electrolyte (concentration of NH4NO3 is 0.5 M, and concentration of o-benzoyl sulfimide is 0.03 g / L). Immerse the iron mesh as a cathode and a platinum sheet electrode as an anode in the electrolyte, control the distance between the two to be 2 cm, and then apply a direct current with an electrochemical workstation and maintain a current of 2 A / cm2 3 Electrochemical deposition is performed for 3 h. After removal, clean and dry the iron mesh for use. Transfer the dried iron mesh to a furnace for three-stage calcination treatment. The first stage of calcination is performed at 500°C for 60 min with a continuous air flow of 40 ml / min. The second stage of calcination is performed at 850°C for 4 h with a continuous flow of hydrogen sulfide gas (H2S concentration: 600 ppm, carrier gas: N2) of 30 ml / min. The third stage of calcination is performed at 350°C for 30 min under water vapor-rich conditions with a continuous flow of nitrogen gas at a rate of 40 ml / min, and deionized water is added to the furnace at a rate of 3 ml / min with a micro-pump injector. The final product is a network-like soil thermal desorption catalyst.

[0029] Catalyst performance evaluation: The soil is completely dried to exclude water interference, and then o-xylene is mixed with the soil to simulate a contaminated soil (o-xylene content: 5%). The network-like soil thermal desorption catalyst is cut into a disc with a diameter of 10 cm for use. The reactor is a quartz tube with a diameter of 5 cm, and 500 g of contaminated soil containing 5% o-xylene is placed in the quartz tube, with a layer of catalyst disc being placed every 5 mm. The soil temperature and hot air temperature are controlled at 120°C, and the reaction is performed for 60 min, with the remaining mass being recorded every 10 min.

[0030] Example 3

[0031] Cut 50 g of iron mesh (pig iron material, 4 mesh in diameter, iron wire diameter 1.2 mm, provided as a screen) and immerse it in a 0.06 M NaCl solution for 120 h to form a layer of Fe203on the surface of the iron wire. After removal, clean and dry the iron mesh for use. Dissolve 3.5895 g of MnS04-4H20 and 1.5688 g of CoCl2-6H20 in 450 g of deionized water to prepare a mixed solution, and then dissolve 14.4000 g of NH4NO3 and 0.018 g of o-benzoyl sulfonamide in the mixed solution to prepare an electrolyte (concentration of NH4NO3 is 0.4 M, and concentration of o-benzoyl sulfonamide is 0.04 g / L). Immerse the iron mesh as a cathode and a platinum sheet electrode as an anode in the electrolyte, control the distance between the two to be 3 cm, and then apply a direct current with an electrochemical workstation and maintain a current of 3 A / cm2 3 Electrochemical deposition is performed for 1 h. After removal, clean and dry the iron mesh for use. Transfer the dried iron mesh to a furnace for three-stage calcination treatment. The first stage of calcination is performed at 550 °C for 30 min with a continuous flow of 50 ml / min of oxygen. The second stage of calcination is performed at 900 °C for 6 h with a continuous flow of 45 ml / min of hydrogen sulfide gas (H2S concentration: 1000 ppm, carrier gas: N2). The third stage of calcination is performed at 300 °C for 40 min under water vapor-rich conditions with a continuous flow of 40 ml / min of nitrogen and a deionized water injection rate of 4 ml / min with a micro-pump injector to obtain a finished network-shaped soil thermal desorption catalyst.

[0032] Catalyst performance evaluation: The soil is completely dried to exclude water interference, and then o-xylene is mixed with the soil to simulate a contaminated soil (o-xylene content of 5%). The network-shaped soil thermal desorption catalyst is cut into a disc with a diameter of 10 cm for use. The reactor is a quartz tube with a diameter of 8 cm, and 500 g of contaminated soil containing 5% o-xylene is weighed and placed in the quartz tube, with a layer of catalyst disc being placed every 5 mm. The soil temperature and hot air temperature are controlled at 140 °C, and the reaction is performed for 60 min, with the remaining mass being recorded every 10 min.

[0033] Example 4

[0034] Cut 50 g of iron mesh (pig iron material, 5 mesh in diameter, iron wire diameter 1.0 mm, provided as a screen) and immerse it in a 0.05 M NaCl solution for 168 h to form a layer of Fe203on the surface of the iron wire. After removal, clean and dry the iron mesh for use. Dissolve 1.4847 g of Mn(NO3)2·6H2O and 3.2435 g of CoSO4·7H2O in 600 g of deionized water to prepare a mixed solution. Then, dissolve 16.0500 g of NH4Cl and 0.012 g of o-benzoyl sulfonamide in the mixed solution to prepare an electrolyte (the concentration of NH4Cl is 0.5 M, and the concentration of o-benzoyl sulfonamide is 0.02 g / L). Immerse the iron mesh as the cathode and the platinum sheet electrode as the anode in the electrolyte, control the distance between the two to be 5 cm, and then apply a direct current with an electrochemical workstation and maintain a current of 1 A / cm2 3 Electrochemical deposition is performed for 3 h. After removal, clean and dry the iron mesh for use. Transfer the dried iron mesh to a furnace for three-stage calcination treatment. The first stage of calcination is performed at 520°C for 45 min with a continuous flow of 30 ml / min of oxygen. The second stage of calcination is performed at 1000°C for 5 h with a continuous flow of 45 ml / min of sulfur dioxide gas (SO2 concentration: 500 ppm, carrier gas: N2). The third stage of calcination is performed at 400°C for 50 min under a water vapor-rich condition with a continuous flow of 50 ml / min of nitrogen gas and a deionized water injection rate of 5 ml / min with a micro-pump injector to obtain a finished network-shaped soil thermal desorption catalyst.

[0035] Catalyst performance evaluation: The soil is completely dried to exclude water interference, and then o-xylene is mixed with the soil to simulate a contaminated soil (o-xylene content: 5%). The network-shaped soil thermal desorption catalyst is cut into a disc with a diameter of 10 cm for use. The reactor is a quartz tube with a diameter of 10 cm, and 500 g of contaminated soil containing 5% of o-xylene is weighed and placed in the quartz tube, with a layer of catalyst disc being placed every 5 mm. The soil temperature and hot air temperature are controlled at 120°C, and the reaction is performed for 60 min, with the remaining mass being recorded every 10 min.

[0036] Comparative Example 1

[0037] Cutting 50 g of iron mesh (pig iron material, 3 mesh in diameter, iron wire diameter 1.0 mm, gathered into a screen for use). Weighing 3.4122 g of MnCl2·4H2O and 3.0890 g of CoSO4·7H2O to dissolve in 400 g of deionized water to prepare a mixed solution, then dissolving 16.0000 g of NH4NO3 and 0.012 g of o-benzoyl sulfonamide in the mixed solution to prepare an electrolyte (the concentration of NH4NO3 is 0.5 M, and the concentration of o-benzoyl sulfonamide is 0.03 g / L). The iron mesh is used as the cathode, and the platinum sheet electrode is used as the anode, both of which are immersed in the electrolyte, and the distance between the two is controlled to be 2 cm, then a direct current is applied by an electrochemical workstation and the current is kept at 2 A / cm 3 Electrochemical deposition is carried out for 3 h. After taking out the iron mesh, it is cleaned and dried for standby. The dried iron mesh is transferred to an atmosphere furnace for three-stage roasting treatment. The first stage roasting is carried out at 500°C for 60 min with 40 ml / min of air continuously flowing in; the second stage roasting is carried out at 850°C for 4 h with 30 ml / min of hydrogen sulfide gas (H2S concentration: 600 ppm, carrier gas: N2) continuously flowing in; the third stage roasting is carried out at 350°C for 30 min under water vapor-rich conditions, with deionized water being added to the furnace at a rate of 3 ml / min by a micro-pump injector, and nitrogen gas being continuously flowed in at a rate of 40 ml / min during the process, to obtain a finished network-like soil thermal desorption catalyst.

[0038] Catalyst performance evaluation: The soil is thoroughly dried to exclude water interference, then o-xylene is mixed with the soil to simulate contaminated soil (o-xylene content 5%). The network-like soil thermal desorption catalyst is cut into a disc with a diameter of 10 cm for standby. The reactor is a quartz tube with a diameter of 5 cm, and 500 g of contaminated soil containing 5% o-xylene is weighed and placed in the quartz tube, with a layer of catalyst disc being laid every 5 mm. The soil temperature and hot air temperature are controlled at 120°C, and the reaction is carried out for 60 min, with the remaining mass being recorded every 10 min.

[0039] Comparison effect: Compared with Example 2, the specific surface area is greatly reduced, and the desorption efficiency is significantly decreased, with a desorption rate of only 60% in 60 min.

[0040] Comparative Example 2

[0041] Cutting 50 g of iron wire mesh (pig iron material, 3 mesh in diameter, iron wire diameter 1.0 mm, gathered into a screen) was immersed in a 0.08 M NaCl solution for 144 h to form a layer of iron oxide on the surface of the iron wire, and then washed and dried for use. 3.4122 g of MnCl2·4H2O and 3.0890 g of CoSO4·7H2O were dissolved in 400 g of deionized water to prepare a mixed solution, and then 16.0000 g of NH4NO3 and 0.012 g of o-benzoyl sulfonamide were dissolved in the mixed solution to prepare an electrolyte (the concentration of NH4NO3 was 0.5 M, and the concentration of o-benzoyl sulfonamide was 0.03 g / L). The iron mesh was used as the cathode, and the platinum sheet electrode was used as the anode, both of which were immersed in the electrolyte, and the distance between them was controlled to be 2 cm. Then a direct current was applied by an electrochemical workstation, and the current was kept at 2 A / cm 3 The electrochemical deposition was carried out for 3 h, and then the iron mesh was taken out, washed and dried for use. The dried iron mesh was transferred to a gas furnace for two-stage calcination treatment. The first stage calcination was carried out at 500°C for 60 min with 40 ml / min of air being continuously introduced. The second stage calcination was carried out at 350°C for 30 min under water vapor-rich conditions, with deionized water being added to the furnace at a rate of 3 ml / min by a micro-pump injector, and nitrogen being continuously introduced at a rate of 40 ml / min during the process. The network-like soil thermal desorption catalyst was obtained.

[0042] Catalyst performance evaluation: The soil was completely dried to exclude the interference of water, and then o-xylene was mixed with the soil to simulate the contaminated soil (o-xylene content 5%). The network-like soil thermal desorption catalyst was cut into a circular piece with a diameter of 10 cm for use. The reactor was a quartz tube with a diameter of 5 cm, and 500 g of contaminated soil containing 5% o-xylene was weighed and placed in the quartz tube, with a layer of catalyst circular piece being laid every 5 mm. The soil temperature and hot air temperature were controlled at 120°C, and the reaction was carried out for 60 min, and the remaining mass was recorded every 10 min.

[0043] Comparison effect: Compared with Example 2, the desorption efficiency decreased significantly when manganese-cobalt oxide was used as the active component.

Claims

1. A networked soil thermal desorption catalyst, characterized by: The catalyst takes manganese-cobalt composite metal sulfide as active component and iron net as carrier; the mass content of active component is 1-12% based on the mass of carrier; the mass ratio of manganese sulfide to cobalt sulfide is 1-15:1-15 based on the mass of active component; The carrier is pretreated by immersing the iron net in sodium chloride aqueous solution to form a ferric oxide layer on the surface.

2. The networked soil thermal desorption catalyst of claim 1, wherein: The mass content of active component is 1-10% based on the mass of carrier; the mass ratio of manganese sulfide to cobalt sulfide is 1-10:1-10 based on the mass of active component.

3. A method of making the networked soil thermal desorption catalyst of claim 1, characterized by: The catalyst is prepared by the following method: (1) Carrier pretreatment: immerse the iron net in sodium chloride aqueous solution to form a ferric oxide layer on the surface, then clean and remove residual sodium chloride, and dry for standby; (2) Active component deposition: prepare a mixed solution of active component, electrolyte and precipitation aid, immerse the treated iron net in the mixed solution, and perform electrochemical deposition; (3) Calcination treatment: place the dried iron net in an atmosphere furnace for three-stage calcination to obtain the finished catalyst; the first-stage calcination is in air or oxygen atmosphere, the second-stage calcination is in hydrogen sulfide or sulfur dioxide atmosphere, and the third-stage calcination is in water vapor atmosphere.

4. The method of claim 3, wherein: In step (1), the iron net is made of cast iron, the iron wire diameter is 0.8-1.2 mm, and the pore size is 2-5 mesh; the concentration of sodium chloride aqueous solution is 0.05-0.1 M, and the immersion time is 120-168 h.

5. The method of claim 3, wherein: In step (2), the active component precursor is a chloride salt or nitrate salt or sulfate salt of manganese and cobalt; the electrolyte in electrochemical deposition is ammonium chloride or ammonium nitrate, and the electrolyte concentration is 0.3-0.5 mol / L; the precipitation aid is o-benzoyl sulfimide, and the concentration of precipitation aid is 0.02-0.04 g / L.

6. The method of claim 3, wherein: The treated iron mesh in step (2) is used as a cathode, a platinum sheet electrode is used as an anode, the distance between the anode and the cathode is 2-5 cm, a direct current power supply is used to control the current size to be 1-3 A / cm 3 , and the deposition time is 1-3 h.

7. The method of claim 3, wherein: In step (3), the first-stage calcination is in air or oxygen atmosphere, the atmosphere gas inlet rate is 30-50 ml / min, the calcination temperature is 500-600℃, and the calcination time is 30-60 min; the second-stage calcination is in hydrogen sulfide or sulfur dioxide atmosphere, nitrogen is used as carrier gas, the concentration of hydrogen sulfide or sulfur dioxide is 500-1000 ppm, the atmosphere gas inlet rate is 30-50 ml / min, the calcination temperature is 800-1000℃, and the calcination time is 4-6 h; the third-stage calcination is in water vapor atmosphere, nitrogen is used as carrier gas, the deionized water inlet rate is 3-5 ml / min, the nitrogen inlet rate is 30-50 ml / min, the calcination temperature is 300-400℃, and the calcination time is 30-60 min.

8. The use of the catalyst of claim 1 in the field of soil thermal desorption.

9. Use according to claim 8, characterized in that: The soil is spread on the surface of the catalyst, and the distance between every two layers of catalyst is 5-15 mm.

Images