External field enhanced microfluidic ellipsoidal denitration and chlorobenzene removal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a preparation method and application of an external field enhanced microfluidic ellipsoidal denitration and dechlorobenzene catalyst. The catalyst takes titanium dioxide as a carrier, a composite oxide of cerium oxide and niobium oxide as an active component, ferroferric oxide as a morphology control agent and a relay coupling electromagnet as a morphology controller; on the basis of the mass of the carrier, the mass percentage of the active component is 10-20%, and the mass percentage of the morphology control agent is 5-10%. The catalyst synthesized by the method has the advantages of being high in specific surface area, good in hydrophobicity, capable of filtering dust and the like, and the aim of low-temperature denitration and chlorobenzene removal of a fixed source can be achieved.

Description

Technical Field

[0001] The present invention relates to an externally field-strengthened microfluidic ellipsoidal denitrifying and dechlorinating benzene catalyst, a preparation method thereof, and an application thereof, belonging to the field of air pollution control. Background Art

[0002] Nitrogen oxides are one of the main pollutants causing air pollution, and the emission sources of NO x mainly include industrial boilers, thermal power plants, steel plants, cement plants, etc. As a typical chlorinated organic compound, chlorobenzene has strong persistence in the environment, is easily introduced into water bodies, soil, and the atmosphere, and has a serious impact on the ecological environment and human health. Chlorobenzene and its derivatives may cause chronic toxicity to aquatic organisms, soil organisms, and humans, and their degradation process is slow, easily accumulating in the environment, resulting in serious pollution problems. Therefore, studying efficient degradation and removal methods of chlorobenzene has important practical significance.

[0003] The SCR technology is a process that uses ammonia or urea to react with NO x and accelerates the reaction through a catalyst to achieve the purpose of efficiently removing NO x . This technology can achieve efficient removal of NO x at a relatively low operating temperature, and has low operating costs and wide applicability, so it is widely used in industrial denitrification. Catalytic oxidation, as an efficient pollutant treatment technology, performs excellently in the degradation of organic compounds. Compared with traditional heat treatment methods and physical adsorption methods, catalytic oxidation has lower energy consumption, higher efficiency, and less by-product generation. Catalytic oxidation of chlorobenzene is particularly important in environmental pollution control, as it can achieve efficient degradation of chlorobenzene at a relatively low temperature, reduce the concentration of chlorobenzene, and thus reduce its harm to the environment.

[0004] Traditional SCR catalysts usually use titanium-based, niobium-based, and molybdenum-based catalysts. However, these catalysts are easily affected by poisoning substances such as sulfur, lead, and dust during high-temperature and long-term use, resulting in a decrease in catalyst activity. At the same time, high-temperature SCR means that enterprises need to heat up the tail gas, which will further increase the enterprise's treatment cost. Since NO x and chlorobenzene often coexist in industrial waste gas, developing a low-temperature catalyst capable of simultaneously removing NO x and chlorobenzene is of great significance. In recent years, researchers have adjusted the composition and structure of the catalyst to enable it to simultaneously catalyze the reactions of NO x and chlorobenzene. For example, transition metal oxide catalysts have good NO x reduction performance and organic matter oxidation ability, and can simultaneously achieve denitrification and dechlorination of benzene at low temperatures. However, NO xThe gas components of chlorobenzene may cause poisoning to the catalyst, resulting in catalyst failure. Therefore, improving the anti-poisoning property of the catalyst and prolonging its service life are the key research topics. Summary of the Invention

[0005] The object of the present invention is to propose an externally field-strengthened microfluidic ellipsoidal denitrification and dechlorobenzene catalyst, its preparation method and application in view of the current situation and existing problems of the treatment of complex flue gas from fixed sources.

[0006] An externally field-strengthened microfluidic ellipsoidal denitrification and dechlorobenzene catalyst, characterized in that: the catalyst uses titanium dioxide as the carrier, the composite oxide of cerium oxide and niobium oxide as the active component, iron tetroxide as the morphology control agent, and a relay-coupled electromagnet as the morphology controller; it is prepared by the combined method of solvothermal growth-externally field-strengthened microfluidic electrospinning; wherein, based on the mass of the carrier, the mass percentage content of the active component is 10-20%, the mass percentage content of the morphology control agent is 5-10%, and the mass ratio of cerium oxide and niobium oxide in the active component is 1:(0.5-2).

[0007] The preparation method of the catalyst is as follows: (1) Preparation of the active component by solvothermal growth method Weigh cerium salt, niobium salt, iron salt, (R)-3-hydroxypyrrolidine hydrochloride, sodium thiosulfate, and deionized water, mix them evenly, place them in a hydrothermal reaction kettle for hydrothermal reaction, filter and dry after the reaction, and then place them in a muffle furnace for low-temperature roasting to obtain a mixed powder of the active component and the morphology control agent; (2) Preparation of polyacrylonitrile nanofibers by externally field-strengthened microfluidic electrospinning Weigh polyacrylonitrile and ethyl acetate, add the mixed powder prepared in step (1) and mix evenly to form spinning dope A. Weigh polyacrylonitrile and ethyl acetate, add titanium salt and mix evenly to form spinning dope B. Connect two syringes to the double channels of the microfluidic chip respectively, and then introduce spinning dope A and spinning dope B into the double channels of the microfluidic chip respectively. Add a relay-coupled electromagnet at the end of the microfluidic chip, use the relay to control the electromagnet to form an intermittent magnetic field, and finally carry out electrospinning on the mixed spinning dope through a microfluidic electrostatic integrated machine to obtain polyacrylonitrile nanofibers loaded with the active component and the morphology control agent; (3) Preparation of the catalyst by roasting method The polyacrylonitrile nanofibers prepared in step (2) are dried and shaped at high temperature in an oven, and then placed in a muffle furnace for rapid heating and roasting to obtain an externally field-strengthened microfluidic ellipsoidal denitrification and dechlorobenzene catalyst.

[0008] In the technical solution of the present invention: in step (1), the cerium salt is cerium nitrate hexahydrate or cerium chloride, the niobium salt is niobium pentachloride, the iron salt is iron nitrate nonahydrate or iron chloride hexahydrate, and the mass ratio of the cerium salt, (R)-3-hydroxypyrrolidine hydrochloride, sodium thiosulfate, and deionized water is 1:(1-2):(3-4):(100-200).

[0009] In the technical solution of the present invention: in step (1), the temperature of the hydrothermal reaction is 140-180 °C, the time of the hydrothermal reaction is 4-8 h, the temperature of drying is 80-100 °C, the time of drying is 6-12 h, the temperature of low-temperature roasting is 300-400 °C, and the time of low-temperature roasting is 2-4 h.

[0010] In the technical solution of the present invention: in step (2), the mass ratio of the polyacrylonitrile, ethyl acetate, and the mixed powder is 1:(6-12):(0.5-1).

[0011] In the technical solution of the present invention: in step (2), the mass ratio of the polyacrylonitrile, ethyl acetate, and the titanium salt is 1:(6-12):(1-2), and the titanium salt is tetrabutyl titanate or tetraethyl titanate.

[0012] In the technical solution of the present invention: in step (2), the relay is a solid-state relay, which realizes a cyclic instruction of energizing the electromagnet for 0.1-0.5 s and then de-energizing for 5-10 s. The electromagnet is a wire with a diameter of 2-3 mm wound around a metal rod with a diameter of 10-20 cm.

[0013] In the technical solution of the present invention: in step (2), the voltage of the spinning is 15-25 kV, and the injection rate of the syringe is 0.5-1.5 mL / h.

[0014] In the technical solution of the present invention: in step (3), the temperature of the high-temperature drying is 100-130 °C, the time of the high-temperature drying is 4-8 h, the rate of rapid heating is 10-20 °C / min, the temperature of roasting is 500-600 °C, and the time of roasting is 2-4 h.

[0015] In the technical solution of the present invention: the application of the above catalyst in the low-temperature denitrification and dechlorobenzene of fixed sources.

[0016] In the technical solution of the present invention: the above fixed source specifically refers to coal-fired power plants, waste incineration, iron and steel sintering, and dry-process cement industries.

[0017] Experimental conditions for evaluating the catalyst activity of the present invention: Take 1 mL of the catalyst with a particle size of 20 - 40 mesh and pour it into a quartz tube with an inner diameter of 6 mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace, and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (800 ppm), NH3 (800 ppm), O2 (10 vol.%), chlorobenzene (400 ppm), SO2 (200 ppm), H2O (5 vol.%), and the rest is N2. The total gas flow rate is 500 mL / min. Control the temperature at 120 - 240 °C, and stay stable for 30 min at every 30 °C. Use gas chromatography to measure the concentration of chlorobenzene and a flue gas analyzer to measure the concentration of NO. The dechlorobenzene efficiency and denitrification efficiency of the catalyst are both higher than 90% in the temperature range of 150 - 210 °C. Beneficial effects:

[0018] (1) In the present invention, sodium thiosulfate is used as a weak reducing agent to partially reduce iron salts, and then a magnetic Fe3O4 morphology control agent powder is prepared by a solvothermal method. At the same time, (R)-3-hydroxypyrrolidine hydrochloride is used as a morphology control agent in the solvothermal method to hydrothermally generate nanosphere particles from cerium salts, niobium salts, and iron salts. CeO2, Nb2O5, and Fe3O4 all have excellent redox properties and can catalytically reduce NO at low temperatures x and catalytically oxidize chlorobenzene; (2) In the present invention, polyacrylonitrile nanofibers are prepared by a microfluidic spinning method. Using ethyl acetate as a solvent and polyacrylonitrile as a templating agent, a titanium dioxide support is prepared by fusing titanium salts. At the same time, the mixed powder of CeO2, Nb2O5, and Fe3O4 is also dissolved in the spinning dope by using the double channels of the microfluidic chip. The double channels can promote the uniform mixing of the support and the mixed powder, thereby promoting the uniform loading of the active components and the morphology control agent on the titanium dioxide support; (3) In the present invention, a solid-state relay is used to control an electromagnet to form an intermittent magnetic field. After the relay-coupled electromagnet, as a morphology controller, generates an intermittent weak magnetic field, the presence of Fe3O4 nanopowders in the spinning solution can cause the spinning mixture to form a nano-ellipsoidal structure when ejected from the spinning machine. Therefore, the catalyst can form a state in which nanofibers and nano-ellipsoidal structures coexist in the microscopic morphology; (4) In the present invention, polyacrylonitrile nanofibers are used as a template. After calcination, the catalyst forms nanofibers and nano-ellipsoidal structures. The nanofibers can partially filter dust during the flue gas treatment process, and the ellipsoidal structure can change the microscopic gas flow field of the catalyst, thereby preventing the catalyst from being physically poisoned due to excessive deposition of poisoning substances such as dust and ammonium bisulfate.

[0019] Therefore, the catalyst prepared by the present invention not only has excellent low-temperature denitrification and dechlorobenzene performance, but also has good sulfur poisoning resistance, and has a certain dust filtration effect. In addition, the catalyst components are environmentally friendly, the preparation process is simple, the cost is low, the cost performance is high, and it has strong application and promotion value. Description of the Drawings

[0020] Figure 1 Schematic diagram of the equipment principle for preparing the catalyst in Example 1; Figure 2 SEM image of the catalyst prepared in Example 1; Figure 3 Denitrification efficiency diagram of the catalysts prepared in Examples 1-3; Figure 4 Dechlorobenzene efficiency diagram of the catalysts prepared in Examples 1-3. Detailed Embodiments

[0021] The present invention will be further described below in conjunction with the embodiments. The embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. Example 1

[0022] (1) Preparation of active components by solvothermal growth method Weigh 2.523 g of cerium nitrate hexahydrate, 1.016 g of niobium pentachloride, 3.926 g of ferric nitrate nonahydrate, 2.523 g of (R)-3-hydroxypyrrolidine hydrochloride, 7.569 g of sodium thiosulfate, and 252.300 g of deionized water, mix them evenly, place them in a hydrothermal reaction kettle, carry out hydrothermal reaction at 140 °C for 8 h, filter after the reaction is completed, place them in an oven and dry at 80 °C for 12 h, and then place them in a muffle furnace and calcine at 300 °C for 4 h to obtain a mixed powder of active components and morphology control agents; (2) Preparation of polyacrylonitrile nanofibers by externally enhanced microfluidic electrospinning method Weigh 4.500 g of polyacrylonitrile, 27.000 g of ethyl acetate, and add 2.250 g of the mixed powder prepared in step (1), mix them evenly to form spinning dope A. Weigh 63.917 g of polyacrylonitrile, 383.502 g of ethyl acetate, and add 63.917 g of tetrabutyl titanate, mix them evenly to form spinning dope B, and combine Figure 1As shown in the figure, two syringes are respectively connected to the double channels of the microfluidic chip. Then, spinning dope A and spinning dope B are respectively introduced into the double channels of the microfluidic chip. A solid-state relay coupled electromagnet (the electromagnet is a 2-mm-diameter iron wire wound around a 10-cm-diameter metal rod) is added to the end of the microfluidic chip. The relay is used to control the electromagnet to form an intermittent magnetic field (a cyclic command of energizing the electromagnet for 0.1 s and then de-energizing for 5 s). Finally, the mixed spinning dope is spun by a microfluidic electrostatics integrated machine (the spinning voltage is 15 kV, and the injection rate of the syringe is 0.5 mL / h) to obtain polyacrylonitrile nanofibers loaded with active components and morphology control agents; (3) Preparation of the catalyst by calcination method The polyacrylonitrile nanofibers prepared in step (2) are dried at 100 °C in an oven for 8 h for shaping, and then placed in a muffle furnace and rapidly heated to 500 °C at a heating rate of 10 °C / min and calcined for 4 h to obtain an externally field-strengthened microfluidic ellipsoidal denitrification and dechlorobenzene catalyst (based on the mass of the carrier, the mass percentage content of the active component is 10%, the mass percentage content of the morphology control agent is 5%, and the mass ratio of cerium oxide to niobium oxide in the active component is 1:0.5. The SEM diagram of the catalyst is as Figure 2 shown); (4) Catalytic activity test Take 1 mL of the catalyst with a particle size of 20 - 40 mesh and pour it into a quartz tube with an inner diameter of 6 mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace, and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet components: NO (800 ppm), NH3 (800 ppm), O2 (10 vol.%), chlorobenzene (400 ppm), SO2 (200 ppm), H2O (5 vol.%), and the rest are N2. The total gas flow rate is 500 mL / min. Control the temperature at 120 - 240 °C and stay stable for 30 min at every 30 °C. Use gas chromatography to measure the chlorobenzene concentration and a flue gas analyzer to measure the NO concentration. The dechlorobenzene efficiency and denitrification efficiency of the catalyst are both higher than 90% in the temperature range of 150 - 210 °C. Example 2

[0023] (1) Preparation of active components by solvothermal growth method Weigh 0.716 g of cerium chloride, 2.033 g of niobium pentachloride, 2.627 g of ferric chloride hexahydrate, 1.432 g of (R)-3-hydroxypyrrolidine hydrochloride, 2.864 g of sodium thiosulfate, and 143.200 g of deionized water, mix them evenly, place them in a hydrothermal reaction kettle, and carry out a hydrothermal reaction at 180 °C for 4 h. After the reaction, filter and place them in an oven to dry at 100 °C for 6 h, and then place them in a muffle furnace for low-temperature calcination at 400 °C for 2 h to obtain a mixed powder of active components and morphology control agents; (2) Preparation of polyacrylonitrile nanofibers by externally enhanced microfluidic electrospinning Weigh 2.250 g of polyacrylonitrile, 27.000 g of ethyl acetate, and add 2.250 g of the mixed powder prepared in step (1), and mix them evenly to form spinning dope A. Weigh 10.711 g of polyacrylonitrile, 128.532 g of ethyl acetate, and add 21.421 g of tetraethyl titanate, and mix them evenly to form spinning dope B. Connect two syringes to the two channels of the microfluidic chip respectively, and then introduce spinning dope A and spinning dope B into the two channels of the microfluidic chip respectively. Add a solid-state relay-coupled electromagnet (the electromagnet is a 3-mm-diameter iron wire wound around a 20-cm-diameter metal rod) at the end of the microfluidic chip, and use the relay to control the electromagnet to form an intermittent magnetic field (execute a cycle instruction of energizing the electromagnet for 0.5 s and then powering off for 10 s). Finally, spin the mixed spinning dope through a microfluidic electrostatic integrated machine (the spinning voltage is 25 kV, and the injection rate of the syringe is 1.5 mL / h) to obtain polyacrylonitrile nanofibers loaded with active components and morphology control agents; (3) Preparation of catalyst by calcination method The polyacrylonitrile nanofibers prepared in step (2) are dried at 130 °C in an oven for 4 h for shaping, and then placed in a muffle furnace and quickly heated to 600 °C at a heating rate of 20 °C / min and calcined for 2 h to obtain an externally enhanced microfluidic ellipsoidal denitrification and dechlorobenzene catalyst (based on the mass of the carrier, the mass percentage of the active component is 20%, the mass percentage of the morphology control agent is 10%, and the mass ratio of cerium oxide to niobium oxide in the active component is 1:2); (4) Catalytic activity test Take 1 mL of the catalyst with a particle size of 20-40 meshes, pour it into a quartz tube with an inner diameter of 6 mm, fix it with quartz wool and wire mesh, place the quartz tube in a tube furnace, and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet components: NO (800 ppm), NH3 (800 ppm), O2 (10 vol.%), chlorobenzene (400 ppm), SO2 (200 ppm), H2O (5 vol.%), and the rest are N2. The total gas flow rate is 500 mL / min. Control the temperature at 120-240 °C, stay stable for 30 min at every 30 °C. Use gas chromatography to measure the concentration of chlorobenzene and a flue gas analyzer to measure the concentration of NO. The dechlorobenzene efficiency and denitrification efficiency of the catalyst are both higher than 90% in the temperature range of 150-210 °C. Example 3

[0024] (1) Preparation of active components by solvothermal growth method Weigh 1.074 g of cerium chloride, 1.525 g of niobium pentachloride, 3.926 g of iron(III) nitrate nonahydrate, 1.611 g of (R)-3-hydroxypyrrolidine hydrochloride, 3.759 g of sodium thiosulfate, and 161.100 g of deionized water, mix them evenly, place them in a hydrothermal reaction kettle, carry out hydrothermal reaction at 160 °C for 6 h. After the reaction, filter and place them in an oven to dry at 90 °C for 8 h, and then place them in a muffle furnace to carry out low-temperature roasting at 350 °C for 3 h to obtain a mixed powder of the active component and the morphology control agent; (2) Preparation of polyacrylonitrile nanofibers by externally field-enhanced microfluidic electrospinning Weigh 3.222 g of polyacrylonitrile and 32.220 g of ethyl acetate, add 2.250 g of the mixed powder prepared in step (1), and mix them evenly to form spinning dope A. Weigh 19.041 g of polyacrylonitrile and 190.410 g of ethyl acetate, add 28.561 g of tetraethyl titanate, and mix them evenly to form spinning dope B. Connect two syringes to the double channels of the microfluidic chip respectively, and then pass spinning dope A and spinning dope B into the double channels of the microfluidic chip respectively. Add a solid-state relay-coupled electromagnet (the electromagnet is a 2.5-mm-diameter iron wire wound around a 15-cm-diameter metal rod) at the end of the microfluidic chip, use the relay to control the electromagnet to form an intermittent magnetic field (perform a cycle instruction of energizing the electromagnet for 0.3 s and then de-energizing for 8 s), and finally carry out electrospinning on the mixed spinning dope through a microfluidic electrostatic integrated machine (the electrospinning voltage is 20 kV, and the injection rate of the syringe is 1.0 mL / h) to obtain polyacrylonitrile nanofibers loaded with the active component and the morphology control agent; (3) Preparation of the catalyst by roasting method High-temperature dry the polyacrylonitrile nanofibers prepared in step (2) in an oven at 120 °C for 6 h for shaping, and then place them in a muffle furnace and quickly heat them up to 550 °C at a heating rate of 15 °C / min for roasting for 3 h to obtain an externally field-enhanced microfluidic ellipsoidal denitrification and dechlorobenzene catalyst (based on the mass of the carrier, the mass percentage content of the active component is 15%, the mass percentage content of the morphology control agent is 7.5%, and the mass ratio of cerium oxide to niobium oxide in the active component is 1:1); (4)Catalytic activity test Take 1 mL of the catalyst with a particle size of 20 - 40 mesh and pour it into a quartz tube with an inner diameter of 6 mm. Fix it with quartz wool and wire mesh. Place the quartz tube in a tube furnace and adjust the actual temperature of the catalytic reaction by controlling the heating temperature of the tube furnace. Inlet gas components: NO (800 ppm), NH3 (800 ppm), O2 (10 vol.%), chlorobenzene (400 ppm), SO2 (200 ppm), H2O (5 vol.%), and the rest is N2. The total gas flow rate is 500 mL / min. Control the temperature at 120 - 240 °C, and stay stable for 30 min at every 30 °C. Use gas chromatography to measure the chlorobenzene concentration and a flue gas analyzer to measure the NO concentration. The dechlorobenzene efficiency and denitrification efficiency of the catalyst are both higher than 90% in the temperature range of 150 - 210 °C.

Claims

1. An externally field-strengthened microfluidic ellipsoidal denitrification and dechlorination benzene catalyst, characterized in that: The catalyst uses titanium dioxide as the carrier, the composite oxide of cerium oxide and niobium oxide as the active component, iron tetroxide as the morphology control agent, and a relay-coupled electromagnet as the morphology controller; it is prepared by the combined method of solvothermal growth - externally field - enhanced microfluidic electrospinning; among them, based on the mass of the carrier, the mass percentage content of the active component is 10 - 20%, the mass percentage content of the morphology control agent is 5 - 10%, and the mass ratio of cerium oxide to niobium oxide in the active component is 1:(0.5 - 2).

2. A method for preparing the catalyst according to claim 1, characterized in that: The preparation method of this catalyst is as follows: (1) Preparation of the active component by solvothermal growth method Weigh cerium salt, niobium salt, iron salt, (R)-3-hydroxypyrrolidine hydrochloride, sodium thiosulfate, and deionized water, mix them evenly, place them in a hydrothermal reaction kettle for hydrothermal reaction. After the reaction is completed, filter and dry, and then place them in a muffle furnace for low-temperature calcination to obtain a mixed powder of the active component and the morphology control agent; (2) Preparation of polyacrylonitrile nanofibers by externally field - enhanced microfluidic electrospinning method Weigh polyacrylonitrile and ethyl acetate, add the mixed powder prepared in step (1), and mix evenly to form spinning dope A. Weigh polyacrylonitrile and ethyl acetate, add titanium salt, and mix evenly to form spinning dope B. Connect two syringes to the two channels of the microfluidic chip respectively, and then introduce spinning dope A and spinning dope B into the two channels of the microfluidic chip respectively. Add a relay - coupled electromagnet at the end of the microfluidic chip, use the relay to control the electromagnet to form an intermittent magnetic field, and finally spin the mixed spinning dope through a microfluidic electrostatic integrated machine to obtain polyacrylonitrile nanofibers loaded with the active component and the morphology control agent; (3) Preparation of the catalyst by calcination method Dry and shape the polyacrylonitrile nanofibers prepared in step (2) at a high temperature in an oven, and then place them in a muffle furnace for rapid heating and calcination to obtain an externally field - enhanced microfluidic ellipsoidal denitrification and dechlorobenzene catalyst.

3. The preparation method according to claim 2, characterized in that: The cerium salt described in step (1) is cerium nitrate hexahydrate or cerium chloride, the niobium salt is niobium pentachloride, the iron salt is iron nitrate nonahydrate or iron chloride hexahydrate, and the mass ratio of cerium salt, (R)-3-hydroxypyrrolidine hydrochloride, sodium thiosulfate, and deionized water is 1:(1 - 2):(3 - 4):(100 - 200).

4. The preparation method according to claim 2, characterized in that: The temperature of the hydrothermal reaction described in step (1) is 140 - 180 °C, the time of the hydrothermal reaction is 4 - 8 h, the temperature of drying is 80 - 100 °C, the time of drying is 6 - 12 h, the temperature of low - temperature calcination is 300 - 400 °C, and the time of low - temperature calcination is 2 - 4 h.

5. The preparation method according to claim 2, wherein: The mass ratio of polyacrylonitrile, ethyl acetate, and the mixed powder described in step (2) is 1:(6 - 12):(0.5 - 1).

6. The preparation method according to claim 2, characterized in that: The mass ratio of polyacrylonitrile, ethyl acetate, and titanium salt described in step (2) is 1:(6 - 12):(1 - 2), and the titanium salt is tetrabutyl titanate or tetraethyl titanate.

7. The preparation method according to claim 2, characterized in that: The relay described in step (2) is a solid - state relay, which realizes a cyclic command of energizing the electromagnet for 0.1 - 0.5 s and then power - off for 5 - 10 s. The electromagnet is an iron wire with a diameter of 2 - 3 mm wound around a metal rod with a diameter of 10 - 20 cm.

8. The preparation method according to claim 2, characterized in that: The voltage of the spinning in step (2) is 15 - 25 kV, and the injection rate of the syringe is 0.5 - 1.5 mL / h.

9. The preparation method according to claim 2, characterized in that: The temperature of the high-temperature drying in step (3) is 100 - 130 °C, the time of the high-temperature drying is 4 - 8 h, the rapid heating rate is 10 - 20 °C / min, the calcination temperature is 500 - 600 °C, and the calcination time is 2 - 4 h.

10. Application of the catalyst according to claim 1 in low-temperature denitrification and dechlorobenzene of fixed sources.

11. Use of the catalyst according to claim 10 in low-temperature denitrification and dechlorobenzene of fixed sources, characterized in that: The fixed source specifically refers to coal-fired power plants, waste incineration, iron and steel sintering, and dry-process cement industries.

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