Method for preparing solid-waste-based bifunctional catalyst by flash evaporation Joule heat and application of solid-waste-based bifunctional catalyst

Abstract

The invention discloses a method for preparing a solid-waste-based bifunctional catalyst through flash evaporation Joule heat and application, and the method comprises the following steps: mixing sewage sludge with a green medium, carrying out a leaching reaction, and carrying out solid-liquid separation to obtain a dealkalized sludge matrix; the method comprises the following steps: pretreating rare earth tailings with a green medium, filtering, and adding a composite acid solution for selective extraction of copper and manganese; carrying out solid-liquid separation on the extracting solution, adding an alkaline solution into a liquid phase to precipitate copper and manganese ions, and mixing the obtained precipitate with a dealkalized sludge matrix and a green medium to obtain a composite precursor; performing flash evaporation Joule heat treatment on the composite precursor to obtain a solid waste based bifunctional catalyst; according to the method, the solid waste-based bifunctional catalyst is rapidly synthesized by taking the sewage sludge subjected to enhanced dealkalization as a matrix and copper and manganese metals extracted from the rare earth tailings as auxiliaries through a flash evaporation Joule heat technology, so that rapid batch production of the catalyst can be realized, and a particle aggregation phenomenon caused by long-time cooling can be effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, and particularly relates to a method and application for preparing a solid waste-based bifunctional catalyst by flash Joule heating. Background Art

[0002] The development of the economy and the acceleration of the industrialization process have led to a continuous increase in wastewater generated by residents' lives and industrial production worldwide. Given the diversity of wastewater types and the complexity of components, the Fenton oxidation process with strong oxidizing and non-selective properties is increasingly applied to the treatment of industrial wastewater. The Fenton oxidation method uses strongly oxidizing hydroxyl radicals to oxidize and remove various refractory organic pollutants in sewage under acidic conditions. However, the final formed sewage sludge contains a large amount of harmful impurities and belongs to typical bulk industrial hazardous waste. However, there is still a lack of large-scale high-value utilization approaches to effectively utilize the sludge. Sewage sludge contains a large amount of resources such as Fe, Al, Si, etc., and has the potential to prepare precursors of multifunctional materials.

[0003] Rare earth tailings are the remaining solid waste generated during the mining and beneficiation of rare earth ores. After rare earth ores are processed through processes such as crushing, grinding, flotation, and magnetic separation, most rare earth elements are extracted. However, due to reasons such as extraction processes and the occurrence states of elements, there are still extremely small amounts of unextracted rare earth elements and a certain amount of metal elements such as copper and manganese remaining. Metal oxides such as copper and manganese have high catalytic activities and can be used to prepare catalyst additives after extraction and enrichment to enhance catalytic activity.

[0004] The flash Joule heating technology is based on the Joule heat effect, where heat is generated when an electric current passes through a material with resistance. When preparing a catalyst, the catalyst precursor is placed in a Joule heat sintering furnace, and an electric current is applied to quickly heat the conductive material in the furnace, creating a high-temperature environment. At the same time, the solvent in the system instantaneously evaporates, causing the catalyst precursor to rapidly concentrate, decompose, or undergo chemical reactions within a short time, realizing the rapid synthesis of the catalyst and greatly shortening the preparation cycle. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the present invention provides a method and application for preparing a solid waste-based bifunctional catalyst by flash Joule heating. Using the strengthened de-alkalized sewage sludge as the matrix and the copper and manganese metals extracted from rare earth tailings as additives, the solid waste-based bifunctional catalyst rapidly synthesized by the flash Joule heating technology can not only realize the rapid batch production of the catalyst, but also the rapid heating and cooling process can effectively avoid the particle aggregation phenomenon caused by long-time cooling, which is beneficial to the formation of uniform and dense fine particles, increasing the specific surface area and active sites of the catalyst and enhancing the catalytic activity of the catalyst.

[0006] The technical solution of the present invention is as follows:

[0007] In the first aspect of the present invention, a method for preparing a solid waste-based bifunctional catalyst by flash Joule heating is provided, comprising the following steps:

[0008] (1) Sludge de-alkalization: Mix sewage sludge with a green medium, carry out a leaching reaction under conditions of heating and stirring, and obtain a de-alkalized sludge matrix through solid-liquid separation.

[0009] (2) Metal extraction: Pretreat rare earth tailings with a green medium and filter, and add a composite acid solution to the pretreated rare earth tailings for selective extraction of copper and manganese.

[0010] (3) Component compounding: Carry out solid-liquid separation on the extraction solution, add an alkaline solution to the liquid phase to precipitate copper and manganese ions, mix the obtained precipitate with the de-alkalized sludge matrix and the green medium, and obtain a composite precursor through heating, stirring, filtering and drying.

[0011] (4) Heat treatment: Carry out flash Joule heat treatment on the composite precursor to obtain a solid waste-based bifunctional catalyst.

[0012] In some embodiments of the present invention, during the sludge de-alkalization treatment, the sewage sludge and the green medium are mixed at a solid-liquid ratio of 1:1 to 1:3, the stirring rate is 200 to 400 r / min, the leaching temperature during the leaching reaction is 30 to 50 °C, and the leaching time is 30 - 50 min.

[0013] In some embodiments of the present invention, the sludge de-alkalization process is carried out in a leaching chamber, and an ultrasonic energy field is applied outside the leaching chamber while stirring, and the ultrasonic power is 800 to 2000 W, preferably 1300 to 1700 W.

[0014] In some embodiments of the present invention, the green medium in the sludge de-alkalization and metal extraction processes is reclaimed water from a sewage treatment plant or desalinated seawater.

[0015] In some embodiments of the present invention, during metal extraction, the rare earth tailings are rinsed with a green medium, and the filtered rare earth tailings and the composite acid solution are mixed at a solid-liquid ratio of 1:3 to 1:6, wherein the composite acid solution is prepared by mixing a citric acid solution and an acetic acid solution at a ratio of 1:1 to 1:2, the concentration of the citric acid solution is 0.5 to 0.7 mol / L, and the concentration of the acetic acid solution is 0.2 to 0.4 mol / L.

[0016] In some embodiments of the present invention, the selective extraction process of copper and manganese is carried out in an element extraction chamber, and a microwave energy field is applied outside the extraction chamber while extracting, the microwave power is 20 to 35 kW, the extraction time is 20 to 35 min, and the extraction temperature is 65 to 85 °C.

[0017] In some embodiments of the present invention, the alkaline solution added during the component compounding process is industrial ammonia water with a concentration of 15% to 23%, and the addition ratio is 10% to 28% of the solution to be reacted;

[0018] Further, the frequency during the heating and stirring process is 300 - 500 r / min, the time is 30 - 50 min, and the temperature is 60 - 90 °C.

[0019] In some embodiments of the present invention, during the heat treatment process, the temperature of the composite precursor for flash Joule heat treatment is 400 - 550 °C.

[0020] In the second aspect of the present invention, a solid waste-based bifunctional catalyst is provided, which is prepared by the method described in the first aspect.

[0021] In the second aspect of the present invention, an application of a solid waste-based bifunctional catalyst is provided. The solid waste-based bifunctional catalyst described in the second aspect is applied to the fields of VOCs gas adsorption and SCR flue gas denitrification.

[0022] One or more technical solutions of the present invention have the following beneficial effects:

[0023] (1) The present invention provides a method for preparing a solid waste-based bifunctional catalyst by flash Joule heat. The alkaline substances in sewage sludge mainly exist in the form of CaSO 4 . In view of the types and occurrence states of alkaline substances, it is proposed to synergistically strengthen the leaching of alkali and alkaline earth metal elements in sludge by ultrasonic cavitation and green media. By using the impact force and micro-jet generated by ultrasonic cavitation, the particles in the solid-liquid two-phase system are strongly impacted and vibrated, the movement of molecules in the solid-liquid two-phase system is intensified, the reaction process is accelerated, and the de-alkalization rate of sewage sludge is greatly improved. Using reclaimed water or seawater desalination water as a green liquid medium can not only reduce environmental pollution, effectively alleviate the problem of water resource shortage, but also greatly reduce the operating cost.

[0024] (2) The present invention uses microwave oscillation coupling with a composite acid system to selectively extract copper and manganese metals from rare earth tailings. By developing a new composite acid system, while achieving efficient leaching of copper and manganese metals, the leaching of impurity metals is reduced, and the selective extraction of copper and manganese metal elements is realized. Using internal heating and stirring and an external microwave field, the molecular movement speed in the reaction system is increased, the surface tension is reduced, and the collision frequency and intensity between molecules are increased, significantly improving the leaching rate.

[0025] (3) The solid waste-based bifunctional catalyst of the present invention is synthesized rapidly by the flash Joule heat technology, with the sewage sludge after enhanced de-alkalization as the matrix and the copper and manganese metals extracted from rare earth tailings as the additives. It can not only achieve the rapid batch production of the catalyst, but also effectively avoid the particle aggregation phenomenon caused by long-time cooling during the rapid heating and cooling process, which is conducive to the formation of uniform and dense fine particles, increasing the specific surface area and active sites of the catalyst and enhancing the catalytic activity of the catalyst. By using two major solid wastes, sewage sludge and rare earth tailings, as the raw material sources of the catalyst to prepare a bifunctional catalyst for VOCs gas adsorption and SCR flue gas denitrification, the high-value utilization of solid waste is realized, expanding a new way for the resource utilization of major solid wastes. Description of the Drawings

[0026] Figure 1 It is a flow chart of the method for preparing the solid waste-based bifunctional catalyst by flash Joule heat of the present invention;

[0027] Figure 2 It is the denitrification activity diagram of the solid waste-based bifunctional catalyst prepared in the embodiment of the present invention;

[0028] Figure 3 It is the VOCs adsorption capacity diagram of the solid waste-based bifunctional catalyst prepared in the embodiment of the present invention. Detailed Embodiments

[0029] The present invention will be further described below in conjunction with the drawings and embodiments.

[0030] In a typical embodiment of the present invention, a method for preparing a solid waste-based bifunctional catalyst by flash Joule heat is proposed. As Figure 1 shown, it includes the following steps:

[0031] Step 1: Add highly water-containing sewage sludge into the leaching chamber, then inject a green medium into the leaching chamber according to a certain solid-liquid ratio, raise the temperature in the leaching chamber and carry out continuous stirring. After the reaction, carry out solid-liquid separation and feed the de-alkalized sludge matrix into the mixing chamber. The sludge is intensively leached and de-alkalized through the above steps.

[0032] Specifically, the green medium uses green and environmentally friendly liquid media such as reclaimed water from sewage treatment plants or desalinated seawater, which can not only reduce environmental pollution, effectively alleviate the problem of water resource shortage, but also greatly reduce the operating cost.

[0033] After adding the green medium, the solid-liquid ratio is 1:1 to 1:3, the stirring rate is 200 to 400 r / min, the leaching temperature is 30 to 50 °C, and the leaching time is 30 - 50 min. When the solid-liquid ratio is within the range of 1:1 to 1:3, the green medium can be fully mixed with the sludge, and there is enough liquid medium to leach out alkali and alkaline earth metal elements. A lower solid-liquid ratio will result in a lack of sufficient liquid medium in the de-alkalization leaching process, affecting the de-alkalization effect of the sludge. A higher de-alkalization rate ensures that the precursor has excellent pore structure and catalytic activity; while a solid-liquid ratio exceeding this range has no obvious improvement effect on the de-alkalization effect of the sludge and will waste a large amount of water resources. When the stirring rate is 200 to 400 r / min, the solid-liquid two-phase system is evenly mixed, and the liquid medium can fully react with the sludge. A lower stirring rate will lead to uneven mixing of the suspension, slower reaction rate, and affect the de-alkalization effect of the sludge; a higher stirring rate has no significant effect on the de-alkalization effect of the sludge and will cause energy waste. When the leaching temperature and leaching time are within the specified range, the de-alkalization effect of the suspension is the best. Below this reaction interval, due to low reaction temperature and short time, the leaching and de-alkalization process cannot fully react, and a large amount of alkali and alkaline earth metal elements still remain inside the sludge, affecting the denitrification activity of the catalyst; while when the leaching temperature and leaching time exceed this range, some free iron and manganese ions in the suspension will enter the liquid phase system under the influence of long-term high temperature, resulting in a decrease in the active components in the catalyst precursor and affecting the denitrification effect of the catalyst.

[0034] Further, in the first step, while stirring, an ultrasonic energy field is applied outside the leaching chamber, and the ultrasonic power is 800 to 2000 W, preferably 1300 to 1700 W. By applying the ultrasonic energy field to strengthen the sludge leaching effect, using the impact force and micro-jet generated by ultrasonic cavitation, the particles in the solid-liquid two-phase system are strongly impacted and vibrated, intensifying the movement of molecules in the solid-liquid two-phase system, accelerating the reaction process, and greatly improving the de-alkalization rate of sewage sludge. Through experiments, it is known that the de-alkalization effect is the best when the ultrasonic power is controlled within 1300 to 1700 W. A lower power range will lead to uneven mixing of the suspension, slower reaction rate, and affect the de-alkalization effect of the sludge; a power range higher than this has no significant effect on the de-alkalization effect of the sludge and will cause energy waste.

[0035] Step 2: Use the green medium to repeatedly rinse the rare earth tailings in the leaching chamber to remove impurities and some water-soluble metal elements. After filtration, inject the rare earth tailings into the element extraction chamber, and then add a composite acid solution according to a certain solid-liquid ratio to selectively extract copper and manganese metals. Through the above steps, the selective directional extraction of tailing metals is achieved.

[0036] Specifically, the green medium uses reclaimed water from a sewage treatment plant or desalinated seawater, etc., as a green and environmentally friendly liquid medium. By using reclaimed water or desalinated seawater, etc., as the green liquid medium, it can not only reduce environmental pollution, effectively alleviate the problem of water resource shortage, but also greatly reduce the operating cost. Through filtration treatment, the alkaline components removed during the leaching process can be filtered out, and solid-liquid separation can be achieved.

[0037] Furthermore, by adding a composite acid solution to react with copper and manganese metals, selective directional extraction of copper and manganese metals is achieved. The solid-liquid ratio after adding the composite acid solution is 1:3 to 1:6. The composite acid solution is prepared by mixing a citric acid solution and an acetic acid solution in a ratio of 1:1 to 1:2. The concentration of the citric acid solution is 0.5 to 1 mol / L, and the concentration of the acetic acid solution is 0.2 to 0.4 mol / L.

[0038] Furthermore, while performing directional extraction, a microwave energy field is applied outside the extraction chamber. The microwave power is 20 to 35 kW, the extraction time is 20 to 35 min, and the extraction temperature is 65 to 85 °C. By applying a microwave energy field outside the element extraction chamber, the extraction effect is enhanced. Since the two extracted metal elements and their occurrence states are different, experiments show that the microwave leaching effect is better here.

[0039] Step 3: Perform solid-liquid separation on the solution after the reaction in Step 2. Add an alkaline solution to the liquid to precipitate free copper and manganese ions. Enrich the precipitate product and add it to the mixing chamber to fully mix with the de-alkalized sludge matrix and the green medium. Perform heating treatment and continuously stir. After the reaction ends, perform solid-liquid separation, and then dry the precursor. Through the above steps, efficient loading of the solid waste auxiliary agent is achieved.

[0040] Specifically, the added alkaline solution is industrial ammonia water with a concentration of 15% to 23%, and the addition ratio is 10% to 28% of the solution to be reacted. The alkaline solution is used to reduce free active metals, so that they are evenly precipitated on the surface of the precursor, improving the catalyst activity and reducing the reaction temperature window.

[0041] Furthermore, the frequency during the heating and stirring process is 300 to 500 r / min, the time is 30 to 50 min, and the temperature is 60 to 90 °C.

[0042] Step 4: Place the dried precursor in a joule heating sintering furnace for rapid heating treatment to obtain a solid waste-based bifunctional catalyst. Among them, rapidly heat to 400-550 °C. In this calcination temperature range, active metal oxides such as iron oxide and copper oxide are generated, which have high catalytic activity. The solid waste-based bifunctional catalyst rapidly synthesized by the flash joule heating technology can not only achieve the rapid batch production of the catalyst, but also the rapid heating and cooling process can effectively avoid the particle aggregation phenomenon caused by long-term cooling, which is conducive to the formation of uniform and dense fine particles, increasing the specific surface area and active sites of the catalyst, and improving the catalytic activity of the catalyst.

[0043] In a typical embodiment of the present invention, a solid waste-based bifunctional catalyst is proposed and prepared by the above method.

[0044] In a typical embodiment of the present invention, an application of a solid waste-based bifunctional catalyst is proposed, such as the above solid waste-based bifunctional catalyst is applied to the fields of VOCs gas adsorption and SCR flue gas denitrification.

[0045] Example 1

[0046] Add sewage sludge with a water content of more than 95% to the leaching chamber, and then inject reclaimed water into the leaching chamber at a solid-liquid ratio of 1:2. Raise the temperature in the leaching chamber to 35 °C, set the stirring rate to 200 r / min, set the power of the ultrasonic energy field outside the leaching chamber to 1000 W. After leaching for 30 min, perform solid-liquid separation on the suspension and pass the de-alkalized sludge matrix into the mixing chamber for standby. Use reclaimed water to repeatedly wash the rare earth tailings in the leaching and filtration chamber to remove impurities and some water-soluble metal elements. After filtration, inject the rare earth tailings into the element extraction chamber, and then add a composite acid solution to it at a solid-liquid ratio of 1:3. The ratio of citric acid solution to acetic acid solution in the composite acid solution is 1:1. Set the power of the external microwave energy field to 25 kW, the extraction temperature to 80 °C, and after reacting for 30 min, perform solid-liquid separation. Add 20% industrial ammonia water to the separated liquid to precipitate free copper and manganese ions. Enrich the precipitate product and add it to the mixing chamber to fully mix with the de-alkalized sludge matrix and reclaimed water. Raise the temperature to 60 °C and stir at a frequency of 400 r / min. After reacting for 45 min, perform filtration treatment and dry the precursor. Place the dried precursor in a joule heating sintering furnace and rapidly heat it to 450 °C to obtain a solid waste-based bifunctional catalyst 1. Detect the SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst through a fixed-bed flue gas test system.

[0047] Example 2

[0048] Add sewage sludge with a water content of more than 95% into the leaching chamber. Subsequently, inject reclaimed water into the leaching chamber at a solid-liquid ratio of 1:1. Raise the temperature in the leaching chamber to 35°C, set the stirring rate at 300 r / min, set the power of the ultrasonic energy field outside the leaching chamber at 1500 W. After leaching for 40 min, perform solid-liquid separation on the suspension and feed the de-alkalized sludge matrix into the mixing chamber for standby. Use reclaimed water to repeatedly wash the rare earth tailings in the leaching and filtering chamber to remove impurities and some water-soluble metal elements. After filtration, inject the rare earth tailings into the element extraction chamber. Subsequently, add a composite acid solution to it at a solid-liquid ratio of 1:5. The ratio of citric acid solution to acetic acid solution in the composite acid solution is 1:1. Set the power of the external microwave energy field at 30 kW, the extraction temperature at 80°C. After reacting for 35 min, perform solid-liquid separation. Add industrial ammonia water with a concentration of 20% to the separated liquid to precipitate free copper and manganese ions. Enrich the precipitate product and add it to the mixing chamber to fully mix with the de-alkalized sludge matrix and reclaimed water. Raise the temperature to 80°C and stir at a frequency of 400 r / min. After reacting for 30 min, perform filtration and dry the precursor. Place the dried precursor in a Joule heat sintering furnace and quickly raise the temperature to 500°C to obtain a solid waste-based bifunctional catalyst 2. Detect the SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst through a fixed-bed flue gas test system.

[0049] Example 3

[0050] Add sewage sludge with a water content of more than 95% into the leaching chamber. Subsequently, inject reclaimed water into the leaching chamber at a solid-liquid ratio of 1:1. Raise the temperature in the leaching chamber to 50°C, set the stirring rate at 200 r / min, set the power of the ultrasonic energy field outside the leaching chamber at 1700 W. After leaching for 40 min, perform solid-liquid separation on the suspension and feed the de-alkalized sludge matrix into the mixing chamber for standby. Use reclaimed water to repeatedly wash the rare earth tailings in the leaching and filtering chamber to remove impurities and some water-soluble metal elements. After filtration, inject the rare earth tailings into the element extraction chamber. Subsequently, add a composite acid solution to it at a solid-liquid ratio of 1:3. The ratio of citric acid solution to acetic acid solution in the composite acid solution is 1:2. Set the power of the external microwave energy field at 30 kW, the extraction temperature at 70°C. After reacting for 30 min, perform solid-liquid separation. Add industrial ammonia water with a concentration of 15% to the separated liquid to precipitate free copper and manganese ions. Enrich the precipitate product and add it to the mixing chamber to fully mix with the de-alkalized sludge matrix and reclaimed water. Raise the temperature to 60°C and stir at a frequency of 400 r / min. After reacting for 45 min, perform filtration and dry the precursor. Place the dried precursor in a Joule heat sintering furnace and quickly raise the temperature to 550°C to obtain a solid waste-based bifunctional catalyst 3. Detect the SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst through a fixed-bed flue gas test system.

[0051] Example 4

[0052] Sewage sludge with a water content of more than 95% is added to the leaching chamber. Subsequently, reclaimed water is injected into the leaching chamber at a solid-liquid ratio of 1:1. The temperature in the leaching chamber is raised to 40 °C, the stirring rate is set at 400 r / min, the power of the ultrasonic energy field outside the leaching chamber is set at 1700 W. After leaching for 40 min, the suspension is subjected to solid-liquid separation, and the de-alkalized sludge matrix is introduced into the mixing chamber for standby. The rare earth tailings in the leaching and filtration chamber are repeatedly washed with reclaimed water to remove impurities and some water-soluble metal elements. After filtration, the rare earth tailings are injected into the element extraction chamber. Subsequently, a composite acid solution is added thereto at a solid-liquid ratio of 1:6. The ratio of citric acid solution to acetic acid solution in the composite acid solution is 1:2. The power of the external microwave energy field is set at 35 kW, the extraction temperature is 80 °C, and after reacting for 35 min, solid-liquid separation is carried out. 23% concentrated industrial ammonia water is added to the separated liquid to precipitate free copper and manganese ions. The precipitate product is enriched and added to the mixing chamber to be fully mixed with the de-alkalized sludge matrix and reclaimed water. The temperature is raised to 90 °C and stirred at a frequency of 500 r / min. After reacting for 50 min, filtration treatment is carried out, and the precursor is dried. The dried precursor is placed in a Joule heat sintering furnace and quickly heated to 550 °C to obtain a solid waste-based bifunctional catalyst 4. The SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst are detected by a fixed-bed flue gas test system.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that in Example 1, ultrasonic treatment was carried out during the sludge de-alkalization process, while in Comparative Example 1, ultrasonic treatment was not carried out during the sludge de-alkalization process to obtain a solid waste-based bifunctional catalyst 5. The SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst are detected by a fixed-bed flue gas test system.

[0055] Comparative Example 2

[0056] The difference from Example 2 is that in the metal extraction process, in Example 2, a composite acid was added for metal extraction, while in Comparative Example 2, only a citric acid solution was added for extraction to obtain a solid waste-based bifunctional catalyst 6. The SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst are detected by a fixed-bed flue gas test system.

[0057] Comparative Example 3

[0058] The difference from Example 3 is that in the metal extraction process, in Example 3, an external microwave energy field was used to heat to the extraction temperature, while in Comparative Example 3, a water bath was used to heat to the extraction temperature of 70 °C to obtain a solid waste-based bifunctional catalyst 7. The SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst are detected by a fixed-bed flue gas test system.

[0059] Comparative Example 4

[0060] The difference from Example 4 is that in Example 4, the composite acid used is a mixed solution of citric acid solution and acetic acid solution, while in Comparative Example 4, an aminosulfonic acid solution and acetic acid solution are used, and the mixing ratio is the same. The solid waste-based bifunctional catalyst 8 is obtained in Comparative Example 4. The SCR flue gas denitrification and VOCs gas adsorption performance of the catalyst are detected by a fixed-bed flue gas test system.

[0061] By detecting the SCR flue gas denitrification and VOCs gas adsorption performance of the solid waste-based bifunctional catalysts prepared in Examples 1-4 and Comparative Examples 1-4, the detection results are as Figure 2 and Figure 3 shown. The denitrification activity of the catalyst 1 obtained in Example 1 can reach 100% at 319 °C, and the VOCs gas adsorption performance is 284.97%; the denitrification activity of the catalyst 2 obtained in Example 2 can reach 100% at 302 °C, and the VOCs gas adsorption performance is 328.57%; the denitrification activity of the catalyst 3 obtained in Example 3 can reach 100% at 309 °C, and the VOCs gas adsorption performance is 296.27%; the denitrification activity of the catalyst 4 obtained in Example 4 can reach 100% at 291 °C, and the VOCs gas adsorption performance is 334.85%; the denitrification activity of the catalyst 5 obtained in Comparative Example 1 is the highest at 338 °C and can only reach 85.63%, and the VOCs gas adsorption performance is 174.34%; the denitrification activity of the catalyst 6 obtained in Comparative Example 2 can reach 100% at 307 °C, and the VOCs gas adsorption performance is 248.87%; the denitrification activity of the catalyst 7 obtained in Comparative Example 3 can reach 100% at 341 °C, and the VOCs gas adsorption performance is 213.55%; the denitrification activity of the catalyst 8 obtained in Comparative Example 4 can reach 100% at 328 °C, and the VOCs gas adsorption performance is 244.57%.

[0062] By comparing and analyzing Example 1 with Comparative Example 1, Example 2 with Comparative Example 2, Example 3 with Comparative Example 3, and Example 4 with Comparative Example 4 respectively, it can be seen that the ultrasonic treatment during the sludge de-alkalization process, the use of a composite solution of citric acid solution and acetic acid solution for metal directional selection during the metal extraction process, and the use of a microwave energy field to heat to the extraction temperature during the metal extraction process in this example can all effectively improve the catalytic performance and gas adsorption performance of the catalyst; at the same time, by comparing and analyzing the solid waste-based bifunctional catalysts prepared in Examples 1-4 and Comparative Examples 1-4 with the original catalyst (referring to the sewage sludge only treated by drying), it can be seen that the method provided by the present invention can greatly improve the activity of the catalyst, reduce the reaction temperature of the catalyst, and at the same time, the adsorption capacity of the catalyst can increase by more than 10 times.

[0063] Although the specific implementation manners of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative efforts on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a solid waste-based bifunctional catalyst by flash Joule heat, characterized in that: The following steps are involved: (1) Sludge de-alkali: Sewage sludge is mixed with green medium, and leaching reaction is carried out under heating and stirring conditions, and the de-alkali sludge matrix is ​​obtained by solid-liquid separation; (2) Metal extraction: Pre-treat the rare earth tailings with green media and filter them, then add composite acid to the pre-treated rare earth tailings for selective extraction of copper and manganese; (3) Component compounding: the extract is subjected to solid-liquid separation, an alkaline solution is added to the liquid phase to precipitate copper and manganese ions, the obtained precipitate is mixed with the dealkalized sludge matrix and the green medium, and the mixture is heated, stirred, filtered and dried to obtain a composite precursor; (4) Heat treatment: The composite precursor is subjected to flash Joule heat treatment to obtain a solid waste-based bifunctional catalyst.

2. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: During the sludge dealkalization treatment, the sewage sludge and the green medium are mixed in a solid-liquid ratio of 1:1 to 1:3, the stirring rate is 200 to 400 r / min, the leaching temperature during the leaching reaction is 30 to 50°C, and the leaching time is 30-50 min.

3. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: The sludge dealkalization process is carried out in a leaching chamber, and an ultrasonic energy field is applied outside the leaching chamber while stirring, and the ultrasonic power is 800-2000W, preferably 1300-1700W.

4. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: The green medium in the sludge dealkalization and metal extraction process uses recycled water from sewage treatment plants or desalinated seawater.

5. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: During metal extraction, the rare earth tailings are washed with a green medium, and the filtered rare earth tailings and the composite acid solution are mixed in a solid-liquid ratio of 1:3 to 1:6, wherein the composite acid solution is prepared by mixing a citric acid solution and an acetic acid solution in a ratio of 1:1 to 1:2, the concentration of the citric acid solution is 0.5 to 0.7 mol / L, and the concentration of the acetic acid solution is 0.2 to 0.4 mol / L.

6. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: The selective extraction process of copper and manganese is carried out in an element extraction chamber. During the extraction, a microwave energy field is applied outside the extraction chamber. The microwave power is 20 to 35 kW, the extraction time is 20 to 35 minutes, and the extraction temperature is 65 to 85°C.

7. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: The alkaline solution added during the component compounding process is industrial ammonia water, with a concentration of 15% to 23%, and the addition ratio is 10% to 28% of the solution to be reacted; Furthermore, the frequency during the heating and stirring process is 300-500 r / min, the time is 30-50 min, and the temperature is 60-90° C.

8. The method for preparing a solid waste-based bifunctional catalyst by flash Joule heat according to claim 1, characterized in that: During the heat treatment process, the temperature of the composite precursor undergoing flash Joule heat treatment is 400-550°C.

9. A solid waste-based bifunctional catalyst, characterized in that: The method is prepared by the method according to any one of claims 1 to 8.

10. An application of a solid waste-based bifunctional catalyst, characterized in that: The solid waste-based bifunctional catalyst as described in claim 9 is applied to the fields of VOCs gas adsorption and SCR flue gas denitrification.

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