Plasma purification device and plasma purification method for diesel engine exhaust

Abstract

The present invention discloses a plasma purification device and a plasma purification method for diesel engine exhaust. The plasma purification device includes a housing; an air inlet and an air outlet respectively located on opposite end surfaces of the housing; an ammonia injection component, an airflow distribution plate, a corona discharge component, an electric coagulation component, an electrostatic adsorption component and an anti-corona catalytic component arranged in sequence inside the housing from the air inlet. The anti-corona catalytic component includes a corona electrode, an auxiliary electrode, an integral SCR catalyst and a grounding electrode arranged in sequence from the direction of the air inlet. The integral SCR catalyst includes a honeycomb substrate and an SCR catalyst based on a Fe-Mn bimetallic unit point coated on the honeycomb substrate, and the anti-corona catalytic component of the integral SCR catalyst can avoid catalyst poisoning. The present invention belongs to the field of air pollution control technology, and mainly solves the problem of controlling nitrogen oxide pollutants.

Description

[0001] This application is a divisional application based on a patent application with an application date of July 22, 2022, application number 202210867570.5, and invention name “Integrated SCR catalyst and preparation method for anti-corona catalytic components”. Technical Field

[0002] The embodiments of the present invention relate to the technical field of air pollution control, and in particular to a plasma purification device and a plasma purification method for diesel engine exhaust. Background Art

[0003] Plasma is a conductive fluid composed of a large number of free electrons, high-energy ions and neutral particles. In the plasma system, a large number of high-energy ions and active groups are in an excited state, which can provide higher activation energy for chemical reactions, allowing chemical reactions that are difficult to occur at room temperature to proceed. In plasma technology, corona discharge has the advantages of strong adaptability, high purification efficiency and simple process, and is widely used to treat gaseous pollutants.

[0004] During the corona discharge process, the dust has a high specific resistance, which makes it difficult to release the charge to the electrode, causing charge accumulation, thus forming a superimposed electric field. When the field strength is large enough, the dust layer is reversely broken down, and point discharge occurs, resulting in a back corona phenomenon. Under the back corona condition, high-energy ions and active groups are generated in situ on the gaps on the surface of the material, thereby forming a back corona plasma. When a catalyst is attached to the surface of the material, the back corona plasma can be closely combined with the catalyst.

[0005] Combining plasma with a selective catalytic reduction (SCR) catalyst can achieve the reduction of nitrogen oxides (NO x ) degradation. Usually, the SCR catalyst is placed in the middle of the plasma discharge area or at the rear end of the plasma, but high-energy ions and active groups are usually generated outside the SCR catalyst, and the plasma is not tightly bound to the SCR catalyst. In the back-corona plasma, high-energy ions and active groups can be generated in the pores inside the SCR catalyst, so the high-energy ions and active groups generated by the back-corona plasma can be tightly bound to the active components of the SCR catalyst.

[0006] Therefore, a method for preparing an integral SCR catalyst for an anti-corona catalytic component and an integral SCR catalyst for an anti-corona catalytic component are proposed, which is expected to improve NO x Purification efficiency. Summary of the invention

[0007] Non-equilibrium plasma technology can generate a large number of high-energy electrons and active free radicals under normal temperature and pressure conditions. The combination of non-equilibrium plasma and selective catalytic reduction (SCR) catalyst can reduce NO in diesel exhaust at room temperature or low temperature.x Reduction to generate nitrogen (N 2 ). The present invention provides a method for preparing a monolithic SCR catalyst for a counter-corona catalytic component and a monolithic SCR catalyst for a counter-corona catalytic component based on non-equilibrium plasma technology.

[0008] According to one aspect of the present invention, a method for preparing an integral SCR catalyst for an anti-corona catalytic component is provided, wherein the preparation method comprises: providing a whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate and a honeycomb matrix, and embedding the honeycomb matrix with the whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate to obtain a mixed material; calcining the mixed material at 900-1200° C. for 2-12 hours and then cooling to grow whiskers on the surface of the honeycomb matrix; providing an SCR catalyst powder based on Fe-Mn bimetallic unit points and mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol and water to obtain an SCR catalyst slurry; coating the SCR catalyst slurry on the inner and outer surfaces of the honeycomb matrix, drying it and then calcining it to obtain an integral SCR catalyst.

[0009] According to another aspect of the present invention, there is provided an integral SCR catalyst for a counter-corona catalytic component, wherein the integral SCR catalyst is prepared according to the preparation method described in the above embodiment.

[0010] According to another aspect of the present invention, there is provided a plasma purification device for diesel engine exhaust, comprising:

[0011] Box;

[0012] An air inlet and an air outlet are respectively located on opposite end surfaces of the outer side of the box;

[0013] The ammonia injection component, the air flow distribution plate, the corona discharge component, the electrocoagulation component, the electrostatic adsorption component and the anti-corona catalytic component are arranged in sequence inside the box from the air inlet.

[0014] The anti-corona catalytic component includes a corona electrode, an auxiliary electrode, an integral SCR catalyst and a grounding electrode arranged in sequence from the direction of the air inlet.

[0015] The monolithic SCR catalyst comprises a honeycomb substrate and a Fe-Mn bimetallic unit-site-based SCR catalyst coated on the honeycomb substrate. The anti-corona catalytic component of the monolithic SCR catalyst can avoid catalyst poisoning.

[0016] According to another aspect of the present invention, a plasma purification method for diesel engine exhaust is provided, wherein the plasma purification method uses the plasma purification device according to any one of the aforementioned embodiments to perform purification treatment, and the plasma purification method comprises:

[0017] The collected diesel engine exhaust gas enters the plasma purification device through the air inlet;

[0018] When the diesel engine exhaust passes through the ammonia injection component, the NH 3 SO in diesel exhaust 2 The reaction generates ammonium sulfate;

[0019] Under the action of air distribution by the air flow distribution plate, the exhaust gas of the diesel engine is evenly distributed inside the plasma purification device;

[0020] The diesel engine exhaust gas passes through the air flow distribution plate and enters the corona discharge component. The particle size of the diesel engine exhaust gas is between 2-50 microns, including soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Negatively charged under the action of negative DC corona at the corona discharge component;

[0021] The diesel engine exhaust gas passes through the corona discharge component and enters the electrocoagulation component. The particle size of the diesel engine exhaust gas is between 0.01-2 microns, and the soot particles (NH 4 ) 2 SO 4 NH 4 HSO 4 Coagulation and agglomeration occur in the electrocoagulation component and are charged, and are captured by the electrostatic adsorption component;

[0022] The diesel exhaust gas captured by the electrostatic adsorption component enters the anti-corona catalytic component. Under the action of the plasma generated in the anti-corona catalytic component, the charged soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 The reverse sputtering is captured by the electrostatic adsorption component to avoid carbon soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Deposit on the surface of SCR catalyst to prevent SCR catalyst from being poisoned and deactivated.

[0023] The purified diesel engine exhaust gas is discharged from the plasma purification device through the gas outlet.

[0024] Other objects and advantages of the present invention will become apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, which will help to provide a comprehensive understanding of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described in detail with reference to the accompanying drawings, in which:

[0026] Figure 1 is a schematic diagram of a plasma purification device for diesel engine exhaust provided by an embodiment of the present invention;

[0027] Figure 2 yes Figure 1 A schematic diagram of a corona discharge component in a plasma purification device for diesel engine exhaust is shown;

[0028] Figure 3 yes Figure 1 A schematic diagram of an electrocoagulation component in a plasma purification device for diesel engine exhaust is shown;

[0029] Figure 4 yes Figure 1 A schematic diagram of an electrostatic adsorption component in a plasma purification device for diesel engine exhaust is shown;

[0030] Figure 5 is a flow chart of a method for preparing a monolithic SCR catalyst for a counter-corona catalytic component according to an exemplary embodiment of the present invention;

[0031] Figure 6 A scanning electron microscope-transmission mode image showing an SCR catalyst powder based on Fe-Mn bimetallic unit sites according to an exemplary embodiment of the present invention;

[0032] Figure 7 A scanning electron microscope image showing a mullite whisker prepared according to a method according to an exemplary embodiment of the present invention;

[0033] Figure 8 A scanning electron microscope image showing aluminum borate whiskers prepared according to a method according to an exemplary embodiment of the present invention;

[0034] Fig. 9 A scanning electron microscope image showing silicon carbide whiskers prepared by a method according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further specifically described below by examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation of the present invention.

[0036] In addition, in the following detailed description, for the purpose of explanation, numerous specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details.

[0037] According to the overall concept of the present invention, a method for preparing an integral SCR catalyst for an anti-corona catalytic component is provided, the preparation method comprising: providing a whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate in a predetermined proportion to a honeycomb matrix and embedding the honeycomb matrix with the whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate to obtain a mixed material; calcining the mixed material at 900-1200° C. for 2-12 hours and then cooling to grow whiskers on the inner and outer surfaces of the honeycomb matrix; providing an SCR catalyst powder based on Fe-Mn bimetallic unit points and mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol and water in a predetermined proportion to obtain an SCR catalyst slurry; coating the SCR catalyst slurry on the inner and outer surfaces of the honeycomb matrix, drying it and then calcining it to obtain an integral SCR catalyst.

[0038] In the embodiment of the present invention, since whiskers grow on the inner and outer surfaces of the honeycomb matrix, the honeycomb matrix has a large specific surface area, which can provide a larger attachment site for the SCR catalyst coating based on the Fe-Mn bimetallic unit point. In addition, a large amount of negative charges are generated during the discharge process and accumulated on the inner and outer surfaces of the integral SCR catalyst. The accumulated charges generate a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, a back-corona plasma is generated. The back-corona plasma includes a large number of high-energy electrons and active groups, which can convert NO in diesel exhaust gas into CO at room temperature or low temperature. x Reduction to generate N 2 .

[0039] The embodiments of the present invention adopt an SCR catalyst based on Fe-Mn bimetallic unit sites. The catalyst uses a molecular sieve as a catalytic carrier, has advantages such as uniform pore size and large specific surface area, and can effectively avoid catalyst poisoning caused by sulfate blockage. In addition, there is a strong interaction between Fe and Mn, and the doping of Fe elements can improve the dispersibility of active metals, which is conducive to the formation of more acid sites, thereby reducing the initial reaction temperature, promoting the catalytic reaction at a lower temperature, and also having a certain improvement effect on the sulfur resistance of the catalyst. Moreover, the active metal exists in atomic-level particles, with a higher utilization rate. Under the same loading condition, more active sites can be provided, thereby increasing its catalytic activity.

[0040] Figure 5 A method for preparing a monolithic SCR catalyst for use in a counter-corona catalytic component according to an exemplary embodiment of the present invention is shown. Figure 5 As shown, the preparation method comprises:

[0041] Obtaining a mixed material: providing a whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate in a predetermined ratio and a honeycomb matrix (including cordierite, alumina, foamed metal (such as nickel) or silicon carbide) and embedding the honeycomb matrix with the whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate to obtain a mixed material;

[0042] Growing whiskers: calcining the mixed material at 900-1200° C., preferably 1000-1100° C. for 2-12 hours (preferably 4-10 hours, more preferably 6 hours), and then cooling (preferably cooling to room temperature) to grow whiskers on the surface of the honeycomb substrate;

[0043] Obtaining SCR catalyst slurry: providing SCR catalyst powder based on Fe-Mn bimetallic unit point and mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol and water in a predetermined ratio to obtain SCR catalyst slurry;

[0044] Obtaining a monolithic SCR catalyst: coating the SCR catalyst slurry on the inner and outer surfaces of the honeycomb substrate on which the whiskers are grown, drying the substrate and then calcining the substrate to obtain a monolithic SCR catalyst.

[0045] In an embodiment, the steps of obtaining the SCR catalyst powder based on the Fe-Mn bimetallic unit site include:

[0046] Mix tetrapropylammonium hydroxide solution, tetraethyl orthosilicate, and water (e.g., deionized water) in a mass ratio of (1-3):(1-3):(2-9) to obtain a first mixed solution, heat the first mixed solution to 30-40° C. (e.g., 35° C.) and continuously stir for 4-8 hours (e.g., 6 hours) to obtain a zeolite precursor gel;

[0047] Dissolve ferric nitrate nonahydrate, manganese nitrate, and ethylenediamine in water (e.g., deionized water) in a mass ratio of (1-4):(15-18):(80-87) to obtain a second mixed solution, drop the second mixed solution into a zeolite precursor gel, mix and stir for 1-3 hours (e.g., 2 hours) to obtain a third mixed solution, transfer the third mixed solution (clarified solution) to a reactor, and crystallize at 160-180° C. (e.g., 170° C.) for 3-5 days to obtain a first reactant;

[0048] The first reactant is subjected to high-temperature reduction (for example, in a muffle furnace) at 400-600° C. (for example, 500° C.) in a reducing atmosphere (for example, any one of argon, nitrogen, argon-hydrogen mixed gas or hydrogen atmosphere) for 4-6 hours (for example, 5 hours) to obtain an SCR catalyst powder.

[0049] In the process of obtaining the SCR catalyst powder of the present invention, a high molecular weight organic matter is first used to complex the iron source (such as iron nitrate) and the manganese source (such as manganese nitrate) so that Fe-Mn is combined in a fixed structure; then the complex is loaded on the zeolite by an in-situ synthesis method; and after crystallization, it is calcined in a reducing atmosphere to remove the organic matter and prevent the active components from being oxidized. That is, under the premise of removing ethylenediamine, it is ensured that the metal active components Fe and Mn are not oxidized.

[0050] Since the active metal exists in the form of macromolecular organic complexes in the zeolite carrier, the macromolecular organic matter is decomposed during the high-temperature hydrogen reduction process, which will result in only the complexed Fe and Mn metals remaining at the location of the original macromolecular organic complex. The volume of the resulting product will be much larger than the volume of the atomic-level particles, reducing the agglomeration between atoms, that is, preventing the agglomeration of the active metals Fe and Mn.

[0051] The SCR catalyst of the embodiment of the present invention is based on the Fe-Mn bimetallic unit site. The bimetallic unit site catalyst ensures that the metal of the independent active site and the carrier are in the same geometric and electronic structure, so that the whole has consistent catalytic behavior. That is, the SCR catalyst loads two metals on one active site, and then realizes a synergistic treatment of the two metals, thereby enhancing the catalytic efficiency of the catalyst.

[0052] In an embodiment, the drying may be performed in a drying oven at 80-120° C. (preferably 100° C.) for 8-24 hours (preferably 12 hours). Alternatively, after high-temperature reduction under a reducing atmosphere, the reaction mixture may be cooled to room temperature after 2 hours.

[0053] In an embodiment, the step of obtaining the SCR catalyst slurry includes: uniformly mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol, and water in a mass ratio of (20-40):(10-30):(10-20):(20-40) to obtain the SCR catalyst slurry. For example, the mass ratio of the SCR catalyst powder to sodium carboxymethyl cellulose, silica sol, and water may be 40:15:13:32.

[0054] In an embodiment, the step of obtaining the monolithic SCR catalyst comprises: coating the SCR catalyst slurry on the inner and outer surfaces of the honeycomb substrate having whiskers on a vacuum coating machine, drying the coated material and then calcining it at 300-600° C. for 2-10 hours to obtain the monolithic SCR catalyst. In an embodiment, it can be dried in a drying oven at 80-120° C. (preferably 100° C.) for 1-4 hours (preferably 2 hours). In an embodiment, it can be calcined in a muffle furnace at 400-500° C. (preferably 450° C.) for 4-8 hours (preferably 6 hours).

[0055] In an embodiment, the method of the present invention can grow mullite whiskers, aluminum borate whiskers or silicon carbide whiskers.

[0056] In an embodiment, when growing mullite whiskers, the whisker raw material is obtained by the following steps: dissolving an organic silicon source in an organic solvent to form a silica sol, treating the silica sol in a water bath at 40-80°C (preferably 60°C) for 0.5-5 hours (preferably 1-4 hours, more preferably 2 hours); dissolving an inorganic aluminum salt in an inorganic solvent to form an inorganic aluminum salt solution; adding the inorganic aluminum salt solution to the silica sol after the water bath treatment to form a silica-alumina mixed sol; treating the silica-alumina mixed sol in a water bath at 40-80°C (preferably 60°C) for 6-18 hours (preferably 10-15 hours, more preferably 12 hours), and grinding to obtain a silica-alumina gel powder, which is the whisker raw material, for example, after drying in an oven (preferably 80-100°C, more preferably 90°C), wherein the silica-alumina gel powder is the whisker raw material.

[0057] In an embodiment, the organic silicon source is at least one of ethyl orthosilicate, methyl orthosilicate and propyl orthosilicate. In an embodiment, the inorganic aluminum salt is at least one of aluminum nitrate, aluminum nitrate nonahydrate, aluminum chloride, basic aluminum chloride and aluminum sulfate. In an embodiment, the inorganic solvent is deionized water. In an embodiment, the organic solvent is anhydrous ethanol. In an embodiment, the molar ratio of aluminum to silicon in the silica-alumina mixed sol is between 2:1-6:1, preferably 3:1-4:1. In an embodiment, the mass ratio of the honeycomb matrix: silica-alumina gel powder: anhydrous aluminum sulfate: anhydrous sodium sulfate is (40-50):(15-25):(15-25):(10-20), for example, 40:25:20:15.

[0058] In an embodiment, for example, an additive is added under stirring conditions to promote the hydrolysis of the organosilicon source to form silica sol, and the additive is 2-4 mL of ammonia water.

[0059] In an embodiment, when growing aluminum borate whiskers, the whisker raw materials include boron trioxide and aluminum nitrate. In an embodiment, the mass ratio of the honeycomb matrix: boron trioxide: aluminum nitrate: anhydrous aluminum sulfate: anhydrous sodium sulfate is (20-40): (10-20): (10-20): (15-25): (10-20), for example, 30:15:20:15:20.

[0060] In an embodiment, when growing silicon carbide whiskers, the whisker raw material is obtained by the following steps: silicon powder and a carbon source are mixed in a Si:C molar ratio of 1:1 and placed in a microwave heating device (preferably a microwave sintering furnace), and silicon carbide powder is obtained by microwave heating. In an embodiment, during the microwave heating process, the microwave frequency is set to 2-3GHz (preferably 2.5GHz), and the microwave source power is set to 3-5kW (preferably 4kW). In an embodiment, the carbon source is at least one of carbon black, petroleum coke, graphite powder and activated carbon. In an embodiment, the mass ratio of the honeycomb matrix: silicon carbide powder: anhydrous aluminum sulfate: anhydrous sodium sulfate is (30-40): (20-30): (15-25): (10-30), for example, 30:20:22:28.

[0061] The preparation method of the integral SCR catalyst comprises: providing a whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate in a predetermined proportion to a honeycomb matrix, and embedding the honeycomb matrix with the whisker raw material, anhydrous aluminum sulfate and anhydrous sodium sulfate to obtain a mixed material; calcining the mixed material at 900-1200° C. for 2-12 hours and then cooling to grow whiskers on the surface of the honeycomb matrix; providing an SCR catalyst powder based on Fe-Mn bimetallic unit points and mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol and water in a predetermined proportion to obtain an SCR catalyst slurry; coating the SCR catalyst slurry on the inner and outer surfaces of the honeycomb matrix, drying the mixture and then calcining the mixture to obtain an integral SCR catalyst.

[0062] Since whiskers grow on the inner and outer surfaces of the honeycomb matrix, the honeycomb matrix has a large specific surface area, which can provide a larger attachment site for the SCR catalyst coating based on the Fe-Mn bimetallic unit point. In addition, a large amount of negative charge is generated during the discharge process and accumulates on the inner and outer surfaces of the monolithic SCR catalyst. The accumulated charge generates a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field reaches or exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, a back corona plasma is generated.

[0063] Return to see Figure 1 The SCR catalyst and the anti-corona catalytic component comprising the same according to the present invention can be applied to Figure 1 A plasma purification device 100 for diesel engine exhaust is shown.

[0064] The specific structural arrangement of the plasma purification device 100 is described below, which includes a housing 1, an air inlet 2 and an air outlet 10. The air inlet 2 is opened on the outer left end surface of the housing 1, and the air outlet 10 is opened on the outer right end surface of the housing 1 accordingly.

[0065] In addition, the plasma purification device 100 also includes an ammonia injection component 3, an airflow distribution plate 4, a corona discharge component 5, an electric coagulation component 6, a rotary cleaning component 7, an electrostatic adsorption component 8 and an anti-corona catalytic component 9 which are arranged in sequence inside the box 1 from the air inlet 2.

[0066] Additionally, as needed Figure 1 In the example shown, the plasma purification device 100 further includes a dust collecting chamber 11, a waterproof valve 12 and a support leg 13. It can be understood by those skilled in the art that the above components can be arranged as needed and are not limited to the illustrated case.

[0067] Specifically, the ammonia injection component 3 is arranged on the left side of the interior of the box body 1; the dust collecting chamber 11 is arranged on the lower end surface of the exterior of the box body 1, and the dust collecting chamber 11 is used to collect carbon soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 , sewage; the drain valve 12 is provided on the outer lower end surface of the dust collecting chamber 11, and the drain valve 12 is used to discharge the sewage in the dust collecting chamber 11; the four supporting legs 13 are respectively arranged at the four vertices of the lower end surface of the box body 1; the corona discharge component 5, the electrocoagulation component 6, the rotary cleaning component 7, and the electrostatic adsorption component 8 are all sequentially installed in the box body 1 in a slot drawer manner. It can be understood that those skilled in the art can select the number of components installed in a slot drawer manner according to needs, rather than being limited to the situation illustrated in the present invention.

[0068] In one example, see Figure 2 The corona discharge component 5 includes a corona electrode 51, a conductive connecting rod 52 and a plate frame 53 which are arranged in sequence from the direction of the air inlet 2. One end of the corona electrode 51 is connected to the conductive connecting rod 52, and the other end is connected to the bottom end of the plate frame 53. The corona discharge component 5 is powered by a negative high-voltage DC power supply.

[0069] In one example, see Figure 3The electrocoagulation component 6 includes a circular mesh plate 61 and a universal pattern conductor wire 62 arranged thereon, and two adjacent rows of universal pattern conductor wires 62 are arranged alternately. The electrocoagulation component 6 is powered by an AC high voltage power supply, and the two adjacent rows of universal pattern conductor wires 62 are respectively connected to the high voltage pole and the grounding pole of the AC high voltage power supply.

[0070] In one example, the rotating cleaning component 7 is located between the electrocoagulation component 6 and the electrostatic adsorption component 8 .

[0071] In one example, see Figure 4 The electrostatic adsorption component 8 includes an adsorption plate 81, a conductive connecting rod 82 and a plate frame 83. One end of the adsorption plate 81 is connected to the conductive connecting rod 82, and the other end is connected to the bottom end of the plate frame 83. The electrostatic adsorption component 8 is powered by a positive high-voltage DC power supply.

[0072] In one example, see again Figure 1 The anti-corona catalytic component 9 includes a corona electrode 91, an auxiliary electrode 92, an integral SCR catalyst 93 and a ground electrode 94 arranged in sequence from the direction of the air inlet 2. The corona electrode 91 and the auxiliary electrode 92 are respectively powered by two negative high-voltage DC power supplies. Preferably, the power electrode 91 and the auxiliary electrode 92 are both made of tungsten wire, and the diameter of the tungsten wire is between 2-6 mm.

[0073] Specifically, the integral SCR catalyst 93 includes an Fe-Mn bimetallic unit-site-based SCR catalyst coated on a honeycomb substrate, and preferably, the SCR catalyst is uniformly loaded on the surface of the honeycomb substrate. The integral SCR catalyst honeycomb substrate is made of cordierite, alumina, foamed metal (nickel) or silicon carbide.

[0074] Whiskers grow on the surface of the honeycomb substrate. The integral SCR catalyst is prepared by coating the SCR catalyst on the surface of the honeycomb substrate and performing drying and calcining treatments. For details, please refer to the preparation method of the integral SCR catalyst shown in the subsequent examples, which will not be repeated here.

[0075] According to another embodiment of the present invention, a plasma purification method for diesel engine exhaust is provided, wherein the plasma purification method for diesel engine exhaust uses the plasma purification device 100 for diesel engine exhaust to perform purification. The plasma purification method comprises: after the collected diesel engine exhaust enters the purification device through the air inlet 2, it passes through the ammonia injection component 3, wherein when passing through the ammonia injection component 3, the injected NH 3 SO in diesel exhaust 2 The reaction produces ammonium sulfate (NH 4 ) 2 SO 4), ammonium bisulfate (NH 4 HSO 4 ); under the action of the air flow distribution plate 4, the diesel engine exhaust is evenly distributed inside the purification device 100; after passing through the air flow distribution plate 4, the diesel engine exhaust passes through the corona discharge component 5, the electrocoagulation component 6, the rotary cleaning component 7, the electrostatic adsorption component 8 and the anti-corona catalytic component 9 in sequence.

[0076] In one example, the diesel engine exhaust collected through the pipeline enters the plasma purification device 100 through the air inlet 2, and after passing through the ammonia injection component 3, the diesel engine exhaust is evenly distributed inside the plasma purification device 100 under the action of the air flow distribution plate 4 and passes through the corona discharge component 5, the electrocoagulation component 6, the rotary cleaning component 7, the electrostatic adsorption component 8 and the anti-corona catalytic component 9 in sequence; when passing through the ammonia injection component 3, NH 3 SO in diesel exhaust 2 The reaction produces (NH 4 ) 2 SO 4 When passing through the corona discharge component 5, the gas near the electrode is ionized to generate a large amount of negative charge due to the negative high voltage DC power supply to the corona electrode 51, and the particle size of the diesel engine exhaust gas is between 2-50 microns of soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Under the action of negative DC corona, the carbon soot particles with a particle size between 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 Difficult to charge.

[0077] When passing through the electrocoagulation component 6, since the AC high voltage power supply supplies power to the universal pattern conductor wire 62 and the two adjacent rows of universal pattern conductor wires 62 are respectively connected to the high voltage pole and the grounding pole of the AC high voltage power supply, the gas near the universal pattern conductor wire 62 is ionized to generate a large amount of charge, and the carbon soot particles with a particle size of 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 The particles aggregate and become charged, and are eventually captured by the electrostatic adsorption component 8 .

[0078] The rotating cleaning component 7 can, for example, periodically perform a rotating flushing cleaning on the electrocoagulation component 6 and the electrostatic adsorption component 8 to remove the soot particles, (NH 4) 2 SO 4 NH 4 HSO 4 .

[0079] When passing through the anti-corona catalytic component 9, since the corona electrode 91 and the auxiliary electrode 92 in the anti-corona catalytic component 9 are respectively powered by two negative high-voltage DC power supplies, the corona electrode 91 ionizes the gas near the corona electrode 91 during the discharge process to generate a large amount of negative charges and accumulates on the inner and outer surfaces of the integral SCR catalyst 93. The accumulated charges generate a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, anti-corona plasma is generated. Under the action of the anti-corona plasma, the charged soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 The reverse sputtering is captured by the electrostatic adsorption component 8 to avoid soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Deposition on the surface of the SCR catalyst prevents the SCR catalyst from being poisoned and deactivated, thus extending the service life of the SCR catalyst. At the same time, the back corona plasma is generated in the pores inside the honeycomb matrix, thereby forming a plasma reaction channel. The free electrons, high-energy ions, and active particles generated in the plasma reaction channel react with NH 3 、NO x Interaction generates NH 2 ,·NH,·N,·H active groups,·NH 2 The active groups of ·NH, ·N, and ·H are closely combined with the active components of the SCR catalyst on the inner and outer surfaces of the integral SCR catalyst 93, giving full play to the advantages of high plasma reactivity and high SCR reaction selectivity, activating the reaction activity of the SCR catalyst, improving the selectivity of the back corona plasma reaction, and promoting the SCR reaction to occur at room temperature or low temperature. Finally, NO in diesel engine exhaust is reduced. x Restored to N 2 The auxiliary electrode 92 suppresses the discharge of the corona electrode 91 from developing into spark discharge; the purified diesel engine exhaust gas is discharged from the plasma purification device 100 through the outlet 10 .

[0080] Three specific embodiments are provided below to explain in detail the integral SCR catalyst 93 and its preparation method and the corresponding exhaust gas treatment process; due to space limitations, not all embodiments are listed one by one.

[0081] Embodiment 1:

[0082] (1) Preparation of monolithic SCR catalyst by growing mullite whisker honeycomb matrix

[0083] The sol-gel method is used to prepare the silica-alumina gel powder. A certain amount of aluminum nitrate is weighed and dissolved in deionized water, and a certain amount of tetraethyl orthosilicate is weighed and dissolved in anhydrous ethanol, so that the Al / Si molar ratio is between 3:1-4:1; 2-4 mL of ammonia water is added to the anhydrous ethanol solution under stirring conditions to catalyze the hydrolysis of tetraethyl orthosilicate to form silica sol, which is treated in a 60°C water bath for 2 hours; then the aluminum nitrate solution is added to the silica sol under stirring conditions, and treated in a 60°C water bath for 12 hours, and the silica-alumina mixed sol is placed in a 90°C oven for drying and then ground to obtain silica-alumina gel powder.

[0084] A certain amount of aluminum sulfate hexadecahydrate or aluminum sulfate 18hydrate is weighed and heated to 400° C. to remove crystal water to obtain anhydrous aluminum sulfate, and then a certain amount of anhydrous aluminum sulfate and anhydrous sodium sulfate are weighed as a composite molten salt system.

[0085] Add silica-alumina gel powder, anhydrous aluminum sulfate and anhydrous sodium sulfate to a cordierite, alumina, metal (nickel) foam or silicon carbide honeycomb matrix, so that the mass ratio of cordierite, alumina, metal (nickel) foam or silicon carbide honeycomb matrix: silica-alumina gel powder: anhydrous aluminum sulfate: anhydrous sodium sulfate is 45:20:20:15, and the cordierite, alumina, metal (nickel) foam or silicon carbide honeycomb matrix is ​​at least partially embedded by silica-alumina gel powder, anhydrous aluminum sulfate and anhydrous sodium sulfate, preferably fully embedded. Place the mixed material in a muffle furnace and roast it at 1000°C for 6 hours, cool it naturally to room temperature, and dense mullite whiskers will grow on the surface of the cordierite, alumina, metal (nickel) foam or silicon carbide honeycomb matrix. Figure 7 , which shows a scanning electron microscope image of mullite whiskers.

[0086] Tetrapropylammonium hydroxide solution, ethyl orthosilicate, and deionized water were mixed in a mass ratio of 2:2:5, and the mixed solution was heated to 35°C and stirred continuously for 6 hours to obtain a zeolite precursor gel. Ferric nitrate nonahydrate, manganese nitrate, and ethylenediamine were dissolved in deionized water in a mass ratio of 3:16:84, and then dripped into the zeolite precursor and mixed and stirred for 2 hours. The clarified liquid was transferred to a reactor and crystallized at 170°C for 4 days. The crystallized product was reduced at high temperature in a hydrogen atmosphere at 450°C for 5 hours, and cooled to room temperature after 2 hours to obtain an SCR catalyst powder. Figure 6 A scanning electron microscope-transmission mode image of an SCR catalyst powder based on Fe-Mn bimetallic unit sites is shown.

[0087] The SCR catalyst powder is uniformly mixed with sodium carboxymethyl cellulose, silica sol and water in a mass ratio of 30:20:15:30 to obtain an SCR catalyst slurry. The SCR catalyst slurry is coated on a cordierite, alumina, foam metal (nickel) or silicon carbide honeycomb substrate with mullite whiskers grown on the surface in a vacuum coating machine. The coated material is placed in a drying oven at 100° C. for 2 hours and then placed in a muffle furnace for calcination at 450° C. for 6 hours.

[0088] (2) Purify exhaust gas

[0089] The diesel engine exhaust gas collected through the pipeline enters the plasma purification device 100 through the air inlet 2, and after passing through the ammonia injection component 3, the diesel engine exhaust gas is evenly distributed inside the plasma purification device 100 under the guidance and air distribution action of the air flow distribution plate 4 and passes through the corona discharge component 5, the electrocoagulation component 6, the rotary cleaning component 7, the electrostatic adsorption component 8 and the anti-corona catalytic component 9 in sequence.

[0090] When passing through the ammonia injection component 3, NH 3 SO in diesel exhaust 2 The reaction produces (NH 4 ) 2 SO 4 NH 4 HSO 4 .

[0091] When passing through the corona discharge component 5, the negative high voltage DC power supply supplies power to the corona electrode 91, so that the gas near the corona electrode is ionized to generate a large amount of negative charge, and the carbon soot particles (NH 4 ) 2 SO 4 NH 4 HSO 4 Under the action of negative DC corona, the carbon soot particles with a particle size between 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 Difficult to charge.

[0092] When passing through the electrocoagulation component 6, since the AC high voltage power supply supplies power to the universal pattern conductor wire 62 and the two adjacent rows of universal pattern conductor wires 62 are respectively connected to the high voltage pole and the grounding pole of the AC high voltage power supply, the gas near the universal pattern wire is ionized to generate a large amount of charge, and the carbon soot particles with a particle size of 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4The particles aggregate and become charged, and are eventually captured by the electrostatic adsorption component 8 .

[0093] The rotating cleaning component 7 can periodically perform a rotating flushing and cleaning on the electrocoagulation component 6 and the electrostatic adsorption component 8 to remove the soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 .

[0094] When passing through the anti-corona catalytic component 9, since the corona electrode 91 and the auxiliary electrode 92 in the anti-corona catalytic component 9 are respectively powered by two negative high-voltage DC power supplies, the corona electrode 91 ionizes the gas near the corona electrode 91 during the discharge process to generate a large amount of negative charges and accumulates on the inner and outer surfaces of the integral SCR catalyst 93. The accumulated charges generate a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, anti-corona plasma is generated. Under the action of the anti-corona plasma, the charged soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 The reverse sputtering is captured by the electrostatic adsorption component 8 to avoid soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Deposition on the surface of the SCR catalyst prevents the SCR catalyst from being poisoned and deactivated, thus extending the service life of the SCR catalyst. At the same time, the back corona plasma is generated in the pores inside the honeycomb matrix, thereby forming a plasma reaction channel. The free electrons, high-energy ions, and active particles generated in the plasma reaction channel react with NH 3 、NO x Interaction generates NH 2 ,·NH,·N,·H active groups,·NH 2 The active groups of ·NH, ·N, and ·H are closely combined with the active components of the SCR catalyst on the inner and outer surfaces of the integral SCR catalyst 93, giving full play to the advantages of high plasma reactivity and high SCR reaction selectivity, activating the reaction activity of the SCR catalyst, improving the selectivity of the back corona plasma reaction, and promoting the SCR reaction to occur at room temperature or low temperature. Finally, NO in diesel engine exhaust is reduced. x Restored to N 2 The auxiliary electrode 92 suppresses the discharge of the corona electrode 91 from developing into spark discharge; the purified diesel engine exhaust gas is discharged from the plasma purification device 100 through the outlet 10 .

[0095] Embodiment 2:

[0096] (1) Preparation of monolithic SCR catalyst by growing aluminum borate whiskers on honeycomb matrix

[0097] A certain amount of aluminum sulfate hexadecahydrate or aluminum sulfate 18hydrate is weighed and heated to 400° C. to remove crystal water to obtain anhydrous aluminum sulfate, and then a certain amount of anhydrous aluminum sulfate and anhydrous sodium sulfate are weighed as a composite molten salt system.

[0098] Boron trioxide, aluminum nitrate, anhydrous aluminum sulfate and anhydrous sodium sulfate are added to a cordierite, alumina, a foamed metal (nickel) or a silicon carbide honeycomb matrix, so that the mass ratio of cordierite, alumina, a foamed metal (nickel) or a silicon carbide honeycomb matrix: boron trioxide: aluminum nitrate: anhydrous aluminum sulfate: anhydrous sodium sulfate is 30:15:15:20:15, and the cordierite, alumina, a foamed metal (nickel) or a silicon carbide honeycomb matrix is ​​at least partially embedded by the boron trioxide, aluminum nitrate, anhydrous aluminum sulfate and anhydrous sodium sulfate, preferably fully and completely embedded. The mixed material is placed in a muffle furnace and roasted at 1000° C. for 6 hours, and naturally cooled to room temperature, and dense aluminum borate whiskers grow on the surface of the cordierite, alumina, a foamed metal (nickel) or a silicon carbide honeycomb matrix. Figure 8 Shown is a scanning electron microscope image of aluminum borate whiskers.

[0099] Tetrapropylammonium hydroxide solution, ethyl orthosilicate, and deionized water were mixed in a mass ratio of 2:2:5, and the mixed solution was heated to 35°C and stirred continuously for 6 hours to obtain a zeolite precursor gel. Ferric nitrate nonahydrate, manganese nitrate, and ethylenediamine were dissolved in deionized water in a mass ratio of 3:16:84, and then dropped into the zeolite precursor and mixed and stirred for 2 hours. The clarified liquid was transferred to a reactor and crystallized at 170°C for 4 days. The crystallized product was reduced at high temperature in a hydrogen atmosphere at 450°C for 5 hours, and then cooled to room temperature after 2 hours.

[0100] The SCR catalyst powder is evenly mixed with sodium carboxymethyl cellulose, silica sol and water in a mass ratio of 30:20:15:35 to obtain an SCR catalyst slurry. The SCR catalyst slurry is coated on a cordierite, alumina, foam metal (nickel) or silicon carbide honeycomb substrate with aluminum borate whiskers grown on the surface in a vacuum coating machine. The coated material is placed in a drying oven at 100° C. for 2 hours and then placed in a muffle furnace for calcination at 450° C. for 6 hours.

[0101] (2) Purify exhaust gas

[0102] The diesel engine exhaust gas collected through the pipeline enters the plasma purification device 100 through the air inlet 2, and after passing through the ammonia injection component 3, the diesel engine exhaust gas is evenly distributed inside the plasma purification device 100 under the guidance and air distribution action of the air flow distribution plate 4 and passes through the corona discharge component 5, the electrocoagulation component 6, the rotary cleaning component 7, the electrostatic adsorption component 8 and the anti-corona catalytic component 9 in sequence.

[0103] When passing through the ammonia injection component 3, NH 3 SO in diesel exhaust 2 The reaction produces (NH 4 ) 2 SO 4 NH 4 HSO 4 .

[0104] When passing through the corona discharge component 5, the negative high voltage DC power supply supplies power to the corona electrode 91, so that the gas near the electrode is ionized to generate a large amount of negative charge, and the carbon soot particles (NH 4 ) 2 SO 4 NH 4 HSO 4 Under the action of negative DC corona, the carbon soot particles with a particle size between 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 Difficult to charge.

[0105] When passing through the electrocoagulation component 6, since the AC high voltage power supply supplies power to the universal pattern conductor wire 62 and the two adjacent rows of universal pattern conductor wires 62 are respectively connected to the high voltage pole and the grounding pole of the AC high voltage power supply, the gas near the universal pattern wire is ionized to generate a large amount of charge, and the carbon soot particles with a particle size of 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 The particles aggregate and become charged, and are eventually captured by the electrostatic adsorption component 8 .

[0106] The rotating cleaning component 7 can periodically perform a rotating flushing and cleaning of the electrocoagulation component 6 and the electrostatic adsorption component 8 to remove the soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 .

[0107] When passing through the anti-corona catalytic component 9, since the corona electrode 91 and the auxiliary electrode 92 in the anti-corona catalytic component 9 are respectively powered by two negative high-voltage DC power supplies, the corona electrode 91 ionizes the gas near the corona electrode 91 during the discharge process to generate a large amount of negative charges and accumulates on the inner and outer surfaces of the integral SCR catalyst 93. The accumulated charges generate a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, anti-corona plasma is generated. Under the action of the anti-corona plasma, the charged soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 The reverse sputtering is captured by the electrostatic adsorption component 8 to avoid soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Deposition on the surface of the SCR catalyst prevents the SCR catalyst from being poisoned and deactivated, thus extending the service life of the SCR catalyst. At the same time, the back corona plasma is generated in the pores inside the honeycomb matrix, thereby forming a plasma reaction channel. The free electrons, high-energy ions, and active particles generated in the plasma reaction channel react with NH 3 、NO x Interaction generates NH 2 ,·NH,·N,·H active groups,·NH 2 The active groups of ·NH, ·N, and ·H are closely combined with the active components of the SCR catalyst on the inner and outer surfaces of the integral SCR catalyst 93, giving full play to the advantages of high plasma reactivity and high SCR reaction selectivity, activating the reaction activity of the SCR catalyst, improving the selectivity of the back corona plasma reaction, and promoting the SCR reaction to occur at room temperature or low temperature. Finally, NO in diesel engine exhaust is reduced. x Restored to N 2 The auxiliary electrode 92 suppresses the discharge of the corona electrode 91 from developing into spark discharge; the purified diesel engine exhaust gas is discharged from the plasma purification device 100 through the outlet 10 .

[0108] Embodiment 3:

[0109] (1) Preparation of monolithic SCR catalyst by growing silicon carbide whisker honeycomb matrix

[0110] A certain amount of carbon black and silicon powder were weighed, with a Si:C molar ratio of 1:1, mixed evenly, and placed in a microwave sintering furnace with a microwave frequency of 2.45 GHz and a microwave source power of 4 kW to obtain silicon carbide powder.

[0111] A certain amount of aluminum sulfate hexadecahydrate or aluminum sulfate 18hydrate is weighed and heated to 400° C. to remove crystal water to obtain anhydrous aluminum sulfate, and then a certain amount of anhydrous aluminum sulfate and anhydrous sodium sulfate are weighed as a composite molten salt system.

[0112] Silicon carbide powder, anhydrous aluminum sulfate and anhydrous sodium sulfate are added to cordierite, alumina, foamed metal (nickel) or silicon carbide honeycomb matrix, so that the mass ratio of cordierite, alumina, foamed metal (nickel) or silicon carbide honeycomb matrix: silicon carbide powder: anhydrous aluminum sulfate: anhydrous sodium sulfate is 35:25:20:20, and the cordierite, alumina, foamed metal (nickel) or silicon carbide honeycomb matrix is ​​at least partially embedded by silicon carbide powder, anhydrous aluminum sulfate and anhydrous sodium sulfate, preferably fully and completely embedded. The mixed material is placed in a muffle furnace and roasted at 900-1200° C. for 6 hours, and naturally cooled to room temperature, and dense silicon carbide whiskers grow on the surface of the cordierite, alumina, foamed metal (nickel) or silicon carbide honeycomb matrix. Fig. 9 A scanning electron microscope image of silicon carbide whiskers is shown.

[0113] Tetrapropylammonium hydroxide solution, ethyl orthosilicate, and deionized water were mixed in a mass ratio of 2:2:5, and the mixed solution was heated to 35°C and stirred continuously for 6 hours to obtain a zeolite precursor gel. Ferric nitrate nonahydrate, manganese nitrate, and ethylenediamine were dissolved in deionized water in a mass ratio of 3:16:84, and then dropped into the zeolite precursor and mixed and stirred for 2 hours. The clarified liquid was transferred to a reactor and crystallized at 170°C for 4 days. The crystallized product was reduced at high temperature in a hydrogen atmosphere at 450°C for 5 hours, and then cooled to room temperature after 2 hours.

[0114] The SCR catalyst powder is evenly mixed with sodium carboxymethyl cellulose, silica sol and water in a mass ratio of 30:20:15:35 to obtain an SCR catalyst slurry. The SCR catalyst slurry is coated on a cordierite, alumina, foam metal (nickel) or silicon carbide honeycomb substrate with silicon carbide whiskers grown on the inner and outer surfaces on a vacuum coating machine. The coated material is placed in a drying oven at 100° C. for 2 hours and then placed in a muffle furnace for calcination at 450° C. for 6 hours.

[0115] (2) Purify exhaust gas

[0116] The diesel engine exhaust gas collected through the pipeline enters the plasma purification device 100 through the air inlet 2, and after passing through the ammonia injection component 3, the diesel engine exhaust gas is evenly distributed inside the plasma purification device 100 under the guidance and air distribution action of the air flow distribution plate 4 and passes through the corona discharge component 5, the electrocoagulation component 6, the rotary cleaning component 7, the electrostatic adsorption component 8 and the anti-corona catalytic component 9 in sequence.

[0117] When passing through the ammonia injection component 3, NH 3 SO in diesel exhaust 2The reaction produces (NH 4 ) 2 SO 4 NH 4 HSO 4 .

[0118] When passing through the corona discharge component 5, the negative high voltage DC power supply supplies power to the corona electrode 91, so that the gas near the electrode is ionized to generate a large amount of negative charge, and the carbon soot particles (NH 4 ) 2 SO 4 NH 4 HSO 4 Under the action of negative DC corona, the carbon soot particles with a particle size between 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 Difficult to charge.

[0119] When passing through the electrocoagulation component 6, since the AC high voltage power supply supplies power to the universal pattern conductor wire 62 and the two adjacent rows of universal pattern conductor wires 62 are respectively connected to the high voltage pole and the grounding pole of the AC high voltage power supply, the gas near the universal pattern conductor wire 62 is ionized to generate a large amount of charge, and the carbon soot particles with a particle size of 0.01-2 microns, (NH 4 ) 2 SO 4 NH 4 HSO 4 The particles aggregate and become charged, and are eventually captured by the electrostatic adsorption component 8 .

[0120] The rotating cleaning component 7 can periodically perform a rotating flushing and cleaning of the electrocoagulation component 6 and the electrostatic adsorption component 8 to remove the soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 .

[0121] When passing through the anti-corona catalytic component 9, since the corona electrode 91 and the auxiliary electrode 92 in the anti-corona catalytic component 9 are respectively powered by two negative high-voltage DC power supplies, the corona electrode 91 ionizes the gas near the corona electrode 91 during the discharge process to generate a large amount of negative charges and accumulates on the inner and outer surfaces of the integral SCR catalyst 93. The accumulated charges generate a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, anti-corona plasma is generated. Under the action of the anti-corona plasma, the charged soot particles, (NH4 ) 2 SO 4 NH 4 HSO 4 The reverse sputtering is captured by the electrostatic adsorption component 8 to avoid soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Deposition on the surface of the SCR catalyst prevents the SCR catalyst from being poisoned and deactivated, thus extending the service life of the SCR catalyst. At the same time, the back corona plasma is generated in the pores inside the honeycomb matrix, thereby forming a plasma reaction channel. The free electrons, high-energy ions, and active particles generated in the plasma reaction channel react with NH 3 、NO x Interaction generates NH 2 ,·NH,·N,·H active groups,·NH 2 The active groups of ·NH, ·N, and ·H are closely combined with the active components of the SCR catalyst on the inner and outer surfaces of the integral SCR catalyst 93, giving full play to the advantages of high plasma reactivity and high SCR reaction selectivity, activating the reaction activity of the SCR catalyst, improving the selectivity of the back corona plasma reaction, and promoting the SCR reaction to occur at room temperature or low temperature. Finally, NO in diesel engine exhaust is reduced. x Restored to N 2 The auxiliary electrode 92 suppresses the discharge of the corona electrode 91 from developing into spark discharge; the purified diesel engine exhaust gas is discharged from the plasma purification device 100 through the outlet 10 .

[0122] The above-described integral SCR catalyst for the anti-corona catalytic component and the preparation method thereof have at least one of the following advantages:

[0123] During the discharge process, the corona electrode ionizes the gas near the corona electrode to generate a large amount of negative charges, which are accumulated on the inner and outer surfaces of the integral SCR catalyst. The accumulated charges generate a superimposed electric field in the pores inside the honeycomb matrix. When the field strength of the superimposed electric field reaches or exceeds the breakdown field strength of the whiskers on the surface of the pores inside the honeycomb matrix, a back-corona plasma is generated. Under the action of the back-corona plasma, charged soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Reverse sputtering to avoid soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4Deposition on the surface of the SCR catalyst prevents the SCR catalyst from being poisoned and deactivated, thus extending the service life of the SCR catalyst. The back corona plasma is generated in the pores inside the honeycomb matrix, thereby forming a plasma reaction channel. The free electrons, high-energy ions, and active particles generated in the plasma reaction channel react with NH 3 、NO x Interaction generates NH 2 ,·NH,·N,·H active groups,·NH 2 , ·NH, ·N, ·H active groups are closely combined with the active components of the SCR catalyst, giving full play to the advantages of high plasma reactivity and high SCR reaction selectivity, activating the reaction activity of the SCR catalyst, improving the reaction selectivity of the back corona plasma, and promoting the SCR reaction at room temperature or low temperature. In addition, the dense whiskers on the inner and outer surfaces of the honeycomb matrix can improve the resistance to soot particles, (NH 4 ) 2 SO 4 NH 4 HSO 4 Interception capture purification efficiency.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A plasma purification device for diesel engine exhaust, comprising: Box; An air inlet and an air outlet are respectively located on opposite end surfaces of the outer side of the box; The ammonia injection component, air flow distribution plate, corona discharge component, electrocoagulation component, electrostatic adsorption component and anti-corona catalytic component are arranged in sequence inside the box from the air inlet. The anti-corona catalytic component includes a corona electrode, an auxiliary electrode, an integral SCR catalyst and a grounding electrode arranged in sequence from the direction of the air inlet. The monolithic SCR catalyst comprises a honeycomb substrate and an Fe-Mn bimetallic unit-site-based SCR catalyst coated on the honeycomb substrate, wherein the anti-corona catalytic component of the monolithic SCR catalyst can avoid catalyst poisoning; The integral SCR catalyst is prepared by the following preparation method: Providing whisker raw materials, anhydrous aluminum sulfate and anhydrous sodium sulfate and a honeycomb matrix, and embedding the honeycomb matrix with the whisker raw materials, anhydrous aluminum sulfate and anhydrous sodium sulfate to obtain a mixed material; The mixed material is calcined at 900-1200° C. for 2-12 hours and then cooled to grow whiskers on the inner and outer surfaces of the honeycomb substrate; Providing SCR catalyst powder based on Fe-Mn bimetallic unit point and mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol and water to obtain SCR catalyst slurry; The SCR catalyst slurry is coated on the inner and outer surfaces of the honeycomb substrate, and then dried and calcined to obtain a monolithic SCR catalyst. The step of providing SCR catalyst powder includes: mixing tetrapropylammonium hydroxide solution, tetraethyl orthosilicate, and water in a mass ratio of (1-3):(1-3):(2-9) to obtain a first mixed solution, heating the first mixed solution to 30-40°C and continuously stirring for 4-8 hours to obtain a zeolite precursor gel; dissolving ferric nitrate nonahydrate, manganese nitrate, and ethylenediamine in water in a mass ratio of (1-4):(15-18):(80-87) to obtain a second mixed solution, dropping the second mixed solution into the zeolite precursor gel, mixing and stirring for 1-3 hours to obtain a third mixed solution, transferring the third mixed solution to a reactor and crystallizing at 160-180°C for 3-5 days to obtain a first reactant, and subjecting the first reactant to a reduction reaction at 400-600°C in a reducing atmosphere for 4-6 hours to obtain the SCR catalyst powder.

2. The plasma purification device according to claim 1, wherein: The honeycomb matrix includes a cordierite honeycomb matrix, an alumina honeycomb matrix, a foamed metal honeycomb matrix or a silicon carbide honeycomb matrix; The step of obtaining the SCR catalyst slurry comprises: mixing the SCR catalyst powder with sodium carboxymethyl cellulose, silica sol and water in a mass ratio of (20-40): (10-30): (10-20): (20-40) to obtain the SCR catalyst slurry; The step of obtaining the integral SCR catalyst comprises: coating the SCR catalyst slurry on the inner and outer surfaces of the honeycomb substrate on a vacuum coating machine, drying the coated material and calcining it at 300-600° C. for 2-10 hours to obtain the integral SCR catalyst.

3. The plasma purification device according to any one of claims 1 to 2, wherein: The corona electrode and the auxiliary electrode are powered by two negative high-voltage DC power supplies respectively; The electrostatic adsorption component includes an adsorption plate, a conductive connecting rod and a plate frame, one end of the adsorption plate is connected to the conductive connecting rod, and the other end of the adsorption plate is connected to the bottom end of the plate frame. The electrostatic adsorption component is powered by a positive high-voltage DC power supply.

4. The plasma purification device according to claim 3, wherein: The corona discharge component comprises a corona electrode, a conductive connecting rod and a plate frame which are arranged in sequence from the direction of the air inlet, one end of the corona electrode is connected to the conductive connecting rod, the other end of the corona electrode is connected to the bottom end of the plate frame, and the corona discharge component is powered by a negative high-voltage DC power supply.

5. The plasma purification device according to claim 4, wherein: The electrocoagulation component includes a circular hole mesh plate and a universal lace conductor wire arranged on the circular hole mesh plate, and two adjacent rows of universal lace conductor wires are arranged in an alternating manner. The electrocoagulation component is powered by an AC high-voltage power supply, and two adjacent rows of universal lace conductor wires are respectively connected to the high-voltage pole and the grounding pole of the AC high-voltage power supply.

6. The plasma purification device according to claim 5, wherein: The plasma purification device further comprises a rotating cleaning component between the electrocoagulation component and the electrostatic adsorption component.

7. The plasma purification device according to claim 6, wherein: The corona discharge component, the electrocoagulation component, the rotary cleaning component and the electrostatic adsorption component are all installed in the box body in sequence in a slot drawer type.

8. The plasma purification device according to claim 7, wherein: The plasma purification device also includes: A dust collecting chamber is arranged outside the box body and located on the lower end surface of the box body; a drain valve disposed outside the dust collecting chamber and on the lower end surface of the dust collecting chamber; and Four supporting legs are located at the four vertices of the lower end surface of the box.

9. A plasma purification method for diesel engine exhaust, the plasma purification using a plasma purification device according to any one of claims 1 to 8, the plasma purification method comprising: The collected diesel engine exhaust gas enters the plasma purification device through the air inlet; When the diesel engine exhaust passes through the ammonia injection component, the NH3 injected by the ammonia injection component reacts with the SO2 in the diesel engine exhaust to form ammonium sulfate; Under the action of air distribution by the air flow distribution plate, the exhaust gas of the diesel engine is evenly distributed inside the plasma purification device; The diesel engine exhaust gas passes through the air flow distribution plate and enters the corona discharge component. The soot particles, (NH4)2SO4, and NH4HSO4 with a particle size of 2-50 microns in the diesel engine exhaust gas are negatively charged under the action of the negative DC corona at the corona discharge component. The diesel engine exhaust gas that has passed through the corona discharge component enters the electro-coagulation component, and the soot particles, (NH4)2SO4, and NH4HSO4 with a particle size between 0.01 and 2 microns in the diesel engine exhaust gas are coagulated and agglomerated in the electro-coagulation component and charged, and are captured by the electrostatic adsorption component; The diesel exhaust captured by the electrostatic adsorption component enters the anti-corona catalytic component. Under the action of the plasma generated in the anti-corona catalytic component, the charged soot particles, (NH4)2SO4, and NH4HSO4 in the diesel exhaust are reversely sputtered and captured by the electrostatic adsorption component, thereby preventing the soot particles, (NH4)2SO4, and NH4HSO4 from depositing on the surface of the SCR catalyst and preventing the SCR catalyst from being poisoned and deactivated. The purified diesel engine exhaust gas is discharged from the plasma purification device through the gas outlet.

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