A supercritical oxidation wastewater treatment process

Abstract

The invention relates to a supercritical oxidation wastewater treatment process, and belongs to the field of wastewater treatment. A self-made composite catalyst is compounded and added into a supercritical oxidation reactor, so as to reduce the corrosion effect of high temperature and high pressure on the equipment, and greatly improve the durability of the equipment; the introduction and modification of ytterbium element can effectively improve the water vapor corrosion resistance of silicon aluminum molecular sieve; aluminum and copper are further uniformly dispersed on the modified molecular sieve carrier through secondary impregnation-sintering, so as to improve the thermal stability of aluminum and copper in supercritical water, and effectively improve the catalytic efficiency in the supercritical water oxygen environment; and since aluminum and copper have different chemical activities, a potential difference is generated, and a plurality of micro primary cells can be formed in the supercritical water oxygen environment, and toxic and harmful pollutants in chemical wastewater can be adsorbed and precipitated, and discharged together with the gas phase products generated by the supercritical water oxygen, so as to further improve the wastewater treatment capacity.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment, and in particular relates to a supercritical oxidation wastewater treatment process. Background Art

[0002] Pure water changes its original physical or chemical properties after use and becomes wastewater containing different types of impurities. Chemical wastewater refers to process wastewater, cooling water, waste washing water, equipment and site flushing water discharged in chemical production. For example, inorganic chemical wastewater mainly includes cooling water. The discharged wastewater contains acids, alkalis, a large amount of salts and suspended matter, and sometimes sulfides and toxic substances. Organic chemical wastewater has diverse components, including wastewater discharged from the processes of synthetic rubber, synthetic plastics, artificial fibers, synthetic dyes, paints and coatings, and pharmaceuticals. It has a strong oxygen-consuming nature and is highly toxic. Moreover, since most of them are artificially synthesized organic compounds, they are highly polluting and difficult to decompose.

[0003] The traditional methods for industrial treatment of chemical wastewater are commonly used biological contact oxidation and incineration. The biological contact oxidation method is a highly efficient water treatment process that mainly uses a biofilm attached to a carrier (commonly known as filler) to purify organic wastewater. However, it can only treat wastewater with a toxic content of less than 1%, and has low oxygen utilization, high power consumption, a long metabolic cycle, and an extremely slow speed. At the same time, the biofilm is not easy to fall off, which may cause filler blockage. The incineration method is to pressurize, filter, and meter the pre-treated wastewater and send it to the top of the furnace arch, where it is sprayed into the furnace for evaporation and incineration by a special nozzle for high-pressure air atomization. However, it is only suitable for wastewater with a high organic concentration. For the treatment of medium and low organic wastewater, the treatment energy consumption and cost are relatively high.

[0004] Supercritical water oxidation technology (SCWO) is an advanced oxidation technology that uses the characteristics of water in a supercritical state of 374°C and a pressure of more than 22.1Mpa, which has both high diffusivity, high solubility and low surface tension of gas and liquid, to rapidly oxidize organic matter and oxidants in supercritical water, converting them into H2O and CO2 to achieve the purpose of detoxification and harmlessness. However, there are many nitrogen-containing organic wastes in chemical wastewater, such as urea, nitrobenzene, etc. This type of wastewater is difficult to degrade. Usually, the supercritical water oxidation temperature of this type of wastewater reaches 500-700°C, which places high requirements on the equipment. Moreover, under such high temperature and high pressure conditions, the hydroxide protective layer on the inner surface of the supercritical water oxidation reactor will also melt due to the high temperature and high pressure, thereby accelerating the corrosion of the equipment and greatly reducing the durability of the equipment. Summary of the invention

[0005] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a supercritical oxidation wastewater treatment process.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] Preparation of composite catalyst:

[0008] Step A1: Weigh the silicon-aluminum molecular sieve and immerse it in deionized water for 12 hours, changing the water three times in the middle, filtering and drying it in an oven at 90° C. for 3 hours, measuring its water absorption rate and setting aside;

[0009] Step A2: Ytterbium nitrate and deionized water are mixed and added to a stirrer, the stirring rate is controlled to be 500-600r / min, and the mixture is stirred for 0.5h, and then the silicon-aluminum molecular sieve is added, and the mixture is stirred and evaporated in a water bath at 80-90°C, and then placed in an oven at 100°C for drying after stirring for 6h; finally, the mixture is transferred to a muffle furnace, the heating rate is set to 10°C / min, the temperature is raised to 700-800°C, and the modified molecular sieve is obtained after the temperature is kept constant for 5h;

[0010] The addition of the rare earth element ytterbium can effectively improve the water vapor corrosion resistance of the silicon aluminum molecular sieve;

[0011] Further, the usage ratio of ytterbium nitrate, deionized water and silica-alumina molecular sieve is 10-15 g: 150 mL: 50 g;

[0012] Step A3: Weigh copper nitrate, aluminum chloride solution and deionized water, mix and add them into a stirrer, control the stirring rate to 700-800r / min, stir for 0.5h, then add the modified molecular sieve, continue stirring for 3-4h, and then stir and evaporate in a water bath at 80°C for 5h, then place the evaporated sample in an oven at 80°C and dry overnight to obtain a blank; finally, transfer the blank to a muffle furnace, set the heating rate to 10°C / min, heat to 800°C, and calcine at high temperature for 6h to obtain a composite catalyst;

[0013] Aluminum and copper are loaded on the modified molecular sieve by secondary impregnation-sintering, which improves the thermal stability of aluminum and copper in a supercritical water-oxygen environment and effectively improves their catalytic efficiency in a supercritical water-oxygen environment;

[0014] Further, the usage ratio of copper nitrate, aluminum chloride solution and modified molecular sieve is 1.5-2.5g:0.5-1g:50g;

[0015] A supercritical oxidation wastewater treatment process comprises the following steps:

[0016] Step S1: filtering the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0017] Step S2: injecting the pretreated wastewater and air into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and injecting the composite catalyst into the supercritical water oxidation reactor through a catalyst delivery pump, increasing the temperature and pressure to oxidize and degrade the pretreated wastewater, cooling the fluid after the reaction through a cooler, and then reducing the pressure to 50 Pa through a pressure reducing valve before entering a gas-liquid separator, and the liquid phase water and gas phase products are discharged from the bottom and top of the separator respectively;

[0018] Further, the dosage ratio of the pretreated wastewater and the composite catalyst is 1 kg: 0.01-0.02 kg;

[0019] Furthermore, in the supercritical water oxidation reactor, the temperature is controlled to be 400-500° C., the pressure is 30-31 MPa, and the residence time is 60-70 s.

[0020] The invention discloses a supercritical oxidation wastewater treatment process. A self-made composite catalyst is compounded and added to a supercritical oxidation reactor to reduce the corrosion effect of high temperature and high pressure on the equipment, thereby greatly improving the durability of the equipment. The composite catalyst adopts an impregnation-sintering method, and ytterbium nitrate is impregnated and sintered to load on a silicon aluminum molecular sieve to form a modified molecular sieve. The introduction and modification of the ytterbium element can effectively improve the water vapor corrosion resistance of the silicon aluminum molecular sieve; aluminum and copper are further uniformly dispersed on the modified molecular sieve carrier through secondary impregnation-sintering, which can improve the thermal stability of aluminum and copper in supercritical water and effectively improve their catalytic efficiency in a supercritical water oxygen environment. Due to the different chemical activities of aluminum and copper, a potential difference is generated, and a plurality of micro primary cells are promoted to be formed in a supercritical water oxygen environment. Under the action of current, various oxides and hydroxides generated in the operation of the primary cells can adsorb and precipitate toxic and harmful pollutants in chemical wastewater, and are discharged together with gas phase products generated by supercritical water oxygen, thereby further improving the wastewater treatment capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 This is a process diagram of supercritical oxidation wastewater treatment of the present invention; DETAILED DESCRIPTION

[0023] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0024] Example 1

[0025] This embodiment discloses a supercritical oxidation wastewater treatment process, comprising the following steps:

[0026] 1) Preparation of composite catalyst:

[0027] a1: Weigh 50 g of silicon-alumina molecular sieve (ZSM-5 molecular sieve from Dalian Haixin Chemical Co., Ltd. is used in this embodiment) and immerse it in deionized water for 12 h, changing the water three times in the middle, filter it and dry it in an oven at 90° C. for 3 h, measure its water absorption rate and set it aside;

[0028] a2: 10g of ytterbium nitrate and 150mL of deionized water were mixed and added to a stirrer, and the stirring rate was controlled to be 500r / min. Then, 50g of silicon-aluminum catalyst was added, and the mixture was stirred and evaporated in a water bath at 80°C. After stirring for 6 hours, the mixture was placed in an oven at 100°C and dried overnight. Finally, the mixture was transferred to a muffle furnace, and the heating rate was set to 10°C / min, and the temperature was raised to 700°C. After being kept at this temperature for 5 hours, the modified molecular sieve was obtained.

[0029] a3: Weigh 1.5g of copper nitrate, 0.5g of aluminum chloride solution (the aluminum chloride solution of Shanghai Aladdin Biochemical Technology Co., Ltd., model A140546, is used in this embodiment) and 50mL of deionized water, mix and feed into a stirrer, control the stirring rate to 700r / min, stir for 0.5h, then add 50g of modified molecular sieve, continue stirring for 3h, and then stir and evaporate in a water bath at 80°C for 5h, then place the evaporated sample in an oven at 80°C and dry overnight to obtain a blank; finally, transfer the blank to a muffle furnace, set the heating rate to 10°C / min, heat to 800°C, and calcine at high temperature for 6h to obtain a composite catalyst;

[0030] 2) A supercritical oxidation wastewater treatment process:

[0031] s1: Filter the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0032] s2: 10kg of pretreated wastewater and air are injected into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and 0.1kg of the composite catalyst is injected into the supercritical water oxidation reactor through a catalyst delivery pump. The temperature is controlled to be 400℃, the pressure is 30Mpa, and the residence time is 60s. The fluid after the reaction is cooled by a cooler, and then reduced to 50pa by a pressure reducing valve before entering the gas-liquid separator. The liquid water and gas products are discharged from the bottom and top of the separator respectively.

[0033] Example 2

[0034] This embodiment discloses a supercritical oxidation wastewater treatment process, comprising the following steps:

[0035] 1) Preparation of composite catalyst:

[0036] a1: Weigh 50g of silica-alumina molecular sieve and immerse it in deionized water for 12h, changing the water three times in the middle, filter it and dry it in an oven at 90℃ for 3h, measure its water absorption rate and set aside;

[0037] a2: 15 g of ytterbium nitrate and 150 mL of deionized water were mixed and added to a stirrer, the stirring rate was controlled to 600 r / min, and the mixture was stirred for 0.5 h. Then, 50 g of silicon-aluminum molecular sieve was added, and the mixture was stirred and evaporated in a water bath at 90 ° C. After stirring for 6 h, the mixture was placed in an oven at 100 ° C and dried overnight; finally, the modified molecular sieve was transferred to a muffle furnace, the heating rate was set to 10 ° C / min, the temperature was raised to 800 ° C, and the modified molecular sieve was obtained after being kept at a constant temperature for 5 h;

[0038] a3: Weigh 2.5g of copper nitrate, 1g of aluminum chloride solution and 50mL of deionized water, mix and add into a stirrer, control the stirring rate to 700r / min, stir for 0.5h, then add 50g of modified molecular sieve, continue stirring for 3h, and then stir and evaporate in a water bath at 80℃ for 5h, then place the evaporated sample in an oven at 80℃ and dry overnight to obtain a blank; finally, transfer the blank into a muffle furnace, set the heating rate to 10℃ / min, heat to 800℃, and calcine at high temperature for 6h to obtain a composite catalyst;

[0039] 2) A supercritical oxidation wastewater treatment process:

[0040] s1: Filter the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0041] s2: 10kg of pretreated wastewater and air are injected into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and 0.2kg of the composite catalyst is injected into the supercritical water oxidation reactor through a catalyst delivery pump. The temperature is controlled to be 500℃, the pressure is 30Mpa, and the residence time is 70s. The fluid after the reaction is cooled by a cooler, and then reduced to 50pa by a pressure reducing valve before entering the gas-liquid separator. The liquid water and gas products are discharged from the bottom and top of the separator respectively.

[0042] Example 3

[0043] This embodiment discloses a supercritical oxidation wastewater treatment process, comprising the following steps:

[0044] 1) Preparation of composite catalyst:

[0045] a1: Weigh 50g of silica-alumina molecular sieve and immerse it in deionized water for 12h, changing the water three times in the middle, filter it and dry it in an oven at 90℃ for 3h, measure its water absorption rate and set aside;

[0046] a2: 13 g of ytterbium nitrate and 150 mL of deionized water were mixed and added to a stirrer, the stirring rate was controlled to 550 r / min, and the mixture was stirred for 0.5 h. Then, 50 g of silicon-aluminum molecular sieve was added, and the mixture was stirred and evaporated in a water bath at 85 °C. After stirring for 6 h, the mixture was placed in an oven at 100 °C and dried overnight. Finally, the modified molecular sieve was transferred to a muffle furnace, the heating rate was set to 10 °C / min, the temperature was raised to 750 °C, and the modified molecular sieve was obtained after being kept at this temperature for 5 h.

[0047] a3: Weigh 2g of copper nitrate, 0.8g of aluminum chloride solution and 50mL of deionized water, mix and add into a stirrer, control the stirring rate to 750r / min, stir for 0.5h, then add 50g of modified molecular sieve, continue stirring for 3.5h, and then stir and evaporate in a water bath at 80℃ for 5h, then place the evaporated sample in an oven at 80℃ and dry overnight to obtain a blank; finally, transfer the blank into a muffle furnace, set the heating rate to 10℃ / min, heat to 800℃, and calcine at high temperature for 6h to obtain a composite catalyst;

[0048] 2) A supercritical oxidation wastewater treatment process:

[0049] s1: Filter the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0050] s2: 10kg of pretreated wastewater and air were injected into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and 0.2kg of the composite catalyst was injected into the supercritical water oxidation reactor through a catalyst delivery pump. The temperature was controlled to be 450℃, the pressure was 30.5Mpa, and the residence time was 65s. The fluid after the reaction was cooled by a cooler, and then reduced to 50pa by a pressure reducing valve before entering the gas-liquid separator. The liquid water and gas products were discharged from the bottom and top of the separator respectively.

[0051] Example 4

[0052] This embodiment discloses a supercritical oxidation wastewater treatment process, comprising the following steps:

[0053] 1) Preparation of composite catalyst:

[0054] a1: Weigh 50g of silica-alumina molecular sieve and immerse it in deionized water for 12h, changing the water three times in the middle, filter it and dry it in an oven at 90℃ for 3h, measure its water absorption rate and set aside;

[0055] a2: 15 g of ytterbium nitrate and 150 mL of deionized water were mixed and added to a stirrer, the stirring rate was controlled to 500 r / min, and the mixture was stirred for 0.5 h. Then, 50 g of silicon-aluminum molecular sieve was added, and the mixture was stirred and evaporated in a water bath at 80 ° C. After stirring for 6 h, the mixture was placed in an oven at 100 ° C and dried overnight; finally, the modified molecular sieve was transferred to a muffle furnace, the heating rate was set to 10 ° C / min, the temperature was raised to 700 ° C, and the modified molecular sieve was obtained after being kept at this temperature for 5 h;

[0056] a3: Weigh 2g of copper nitrate, 1g of aluminum chloride solution and 50mL of deionized water, mix and add into a stirrer, control the stirring rate to 700r / min, stir for 0.5h, then add 50g of modified molecular sieve, continue stirring for 3h, and then stir and evaporate in a water bath at 80℃ for 5h, then place the evaporated sample in an oven at 80℃ and dry overnight to obtain a blank; finally, transfer the blank into a muffle furnace, set the heating rate to 10℃ / min, heat to 800℃, and calcine at high temperature for 6h to obtain a composite catalyst;

[0057] 2) A supercritical oxidation wastewater treatment process:

[0058] s1: Filter the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0059] s2: 10kg of pretreated wastewater and air were injected into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and 0.15kg of the composite catalyst was injected into the supercritical water oxidation reactor through a catalyst delivery pump. The temperature was controlled to be 475℃, the pressure was 30Mpa, and the residence time was 65s. The fluid after the reaction was cooled by a cooler, and then reduced to 50pa by a pressure reducing valve before entering the gas-liquid separator. The liquid water and gas products were discharged from the bottom and top of the separator respectively.

[0060] Comparative Example 1

[0061] This comparative example discloses a supercritical oxidation wastewater treatment process, comprising the following steps:

[0062] s1: Filter the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0063] s2: 10kg of pretreated wastewater and air were injected into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively. The temperature was controlled at 374℃, the pressure was 22.1Mpa, and the residence time was 65s. The fluid after the reaction was cooled by a cooler, and then reduced to 50pa by a pressure reducing valve before entering the gas-liquid separator. The liquid water and gas products were discharged from the bottom and top of the separator respectively.

[0064] Comparative Example 2

[0065] This comparative example discloses a supercritical oxidation wastewater treatment process, comprising the following steps:

[0066] 1) Preparation of composite catalyst:

[0067] a1: Weigh 50g of silica-alumina molecular sieve and immerse it in deionized water for 12h, changing the water three times in the middle, filter it and dry it in an oven at 90℃ for 3h, measure its water absorption rate and set aside;

[0068] a2: 15 g of ytterbium nitrate and 150 mL of deionized water were mixed and added to a stirrer, the stirring rate was controlled to 600 r / min, and the mixture was stirred for 0.5 h. Then, 50 g of silicon-aluminum molecular sieve was added, and the mixture was stirred and evaporated in a water bath at 90 ° C. After stirring for 6 h, the mixture was placed in an oven at 100 ° C and dried overnight; finally, the modified molecular sieve was transferred to a muffle furnace, the heating rate was set to 10 ° C / min, the temperature was raised to 800 ° C, and the modified molecular sieve was obtained after being kept at a constant temperature for 5 h;

[0069] a3: Weigh 2.5g of copper nitrate, 1g of aluminum chloride solution and 50mL of deionized water, mix and add into a stirrer, control the stirring rate to 700r / min, stir for 0.5h, then add 50g of modified molecular sieve, continue stirring for 3h, and then stir and evaporate in a water bath at 80℃ for 5h, then place the evaporated sample in an oven at 80℃ and dry overnight to obtain a blank; finally, transfer the blank into a muffle furnace, set the heating rate to 10℃ / min, heat to 800℃, and calcine at high temperature for 6h to obtain a composite catalyst;

[0070] 2) A supercritical oxidation wastewater treatment process:

[0071] s1: Filter the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater;

[0072] s2: 10kg of pretreated wastewater and air are injected into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and 0.2kg of the composite catalyst is injected into the supercritical water oxidation reactor through a catalyst delivery pump. The temperature is controlled to be 600℃, the pressure is 30Mpa, and the residence time is 70s. The fluid after the reaction is cooled by a cooler, and then reduced to 50pa by a pressure reducing valve before entering the gas-liquid separator. The liquid water and gas products are discharged from the bottom and top of the separator respectively.

[0073] Application Example 1

[0074] A supercritical oxidation wastewater treatment process disclosed in Examples 1-4 and Comparative Examples 1-2 was applied to high-concentration fine chemical wastewater (organic matter concentration was 20%, COD = 30000 mg / L).

[0075] Application Example 2

[0076] A supercritical oxidation wastewater treatment process disclosed in Examples 1-4 and Comparative Examples 1-2 was applied to pharmaceutical wastewater (organic matter concentration was 10%, COD = 15000 mg / L).

[0077] In order to facilitate testing of a supercritical oxidation wastewater treatment process disclosed in the present invention, the wastewater treated by Application Example 1 and Application Example 2 was tested, and the specific test results are shown in Table 1:

[0078] Table 1

[0079]

[0080] It can be seen from the data in Table 1 that the COD removal rate of a supercritical oxidation wastewater treatment process for chemical wastewater disclosed in the present invention is more than 99.94%, which is better than the supercritical oxidation wastewater treatment process disclosed in Comparative Example 1, and is similar to the COD removal rate of a supercritical oxidation wastewater treatment process for chemical wastewater disclosed in Comparative Example 2, indicating that a supercritical oxidation wastewater treatment process disclosed in the present invention can obtain good catalytic effect at lower temperature and pressure.

[0081] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

[0082] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

Claims

1. A supercritical oxidation wastewater treatment process, characterized in that: The steps include: Step S1: filtering the chemical wastewater to remove particulate solids and suspended matter to obtain pretreated wastewater; Step S2: injecting the pretreated wastewater and air into the supercritical water oxidation reactor through a high-pressure pump and a compressor respectively, and injecting the composite catalyst into the supercritical water oxidation reactor through a catalyst delivery pump, increasing the temperature and pressure to oxidize and degrade the pretreated wastewater, cooling the fluid after the reaction through a cooler, and then reducing the pressure to 50 Pa through a pressure reducing valve before entering a gas-liquid separator, and the liquid phase water and gas phase products are discharged from the bottom and top of the separator respectively; In step S2, the usage ratio of pretreated wastewater and composite catalyst is 1kg:0.01-0.02kg; In step S2, in the supercritical water oxidation reactor, the temperature is controlled to be 400-500°C, the pressure is 30-31Mpa, and the residence time is 60-70s; The preparation method of the composite catalyst is as follows: Step A1: Weigh the silicon-aluminum molecular sieve and immerse it in deionized water for 12 hours, changing the water three times in the middle, filtering and drying it in an oven at 90° C. for 3 hours, measuring its water absorption rate and setting it aside; Step A2: 10-15g of ytterbium nitrate and deionized water are mixed and then added with silicon-aluminum molecular sieve, and the mixture is stirred and evaporated in a water bath at 80-90°C, and then placed in an oven at 100°C for drying overnight after stirring for 6 hours; finally, the mixture is transferred to a muffle furnace, heated to 700-800°C, and kept at the constant temperature for 5 hours to obtain a modified molecular sieve; Step A3: Weigh copper nitrate, aluminum chloride solution and deionized water, mix and add, stir for 0.5h, then add modified molecular sieve, continue stirring for 3-4h, then stir and evaporate in a water bath at 80°C for 5h, then place the evaporated sample in an oven at 80°C and dry overnight to obtain a blank; finally, transfer the blank to a muffle furnace, set the heating rate to 10°C / min, heat to 800°C, and calcine at high temperature for 6h to obtain a composite catalyst.

2. A supercritical oxidation wastewater treatment process according to claim 1, characterized in that: In step A2, the usage ratio of ytterbium nitrate, deionized water and silica-alumina molecular sieve is 10-15 g:150 mL:50 g.

3. A supercritical oxidation wastewater treatment process according to claim 1, characterized in that: The usage ratio of copper nitrate, aluminum chloride solution and modified molecular sieve is 1.5-2.5g:0.5-1g:50g.

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