Apparatus for converting biomass tar with plasma multi-mode coupling catalyst

Abstract

The application discloses a device for converting biomass tar by using a plasma multi-mode coupling catalyst, and the plasma reactor comprises a coaxial DBD body discharge structure and a structural catalyst passage inner discharge structure; an alternating-current high-voltage electrode rod, a dielectric tube and a ground electrode constitute the coaxial DBD body discharge in the inner cavity of the dielectric tube; catalyst particles in the inner cavity of the dielectric tube and the structural catalyst are jointly acted on by alternating-current and direct-current electric fields, a voltage difference is formed between the upper end and the lower end of the structural catalyst to constitute the structural catalyst passage inner discharge; meanwhile, the gas activated by the plasma and flowing out of the structural catalyst makes the catalyst particles present a fluidized state, and the interaction between the catalyst and the plasma is realized by combining the coaxial DBD body discharge. The application is driven by a direct-current alternating-current dual power source, and the fluidized bed and the packed bed two modes are coupled with the catalyst to improve the overall reaction efficiency, the rapid and efficient treatment of the tar can be realized, and the operability and the economy of the tar treatment process are improved.

Description

Technical Field

[0001] This invention relates to the field of plasma treatment technology, and more specifically to an apparatus for converting biomass tar using a plasma multimode coupled catalyst. Background Technology

[0002] Biomass is a green and widely distributed renewable energy source that has attracted widespread attention due to its potential energy development value. Gasification technology is a crucial pathway for biomass energy utilization, and its high conversion efficiency and diverse application prospects have made it a research hotspot. During the gasification process, the main product, syngas, is an important raw material in the energy and chemical industry. However, tar is inevitably generated during gasification. This complex organic pollutant is mainly composed of various condensable hydrocarbons, including monocyclic to polycyclic aromatic compounds, oxygen-containing organic matter, and polycyclic aromatic hydrocarbons. The presence of tar not only causes pipeline blockage and equipment corrosion, affecting the stability of gasification unit operation, but also reduces the quality of syngas and the utilization efficiency of biomass, becoming a significant technical obstacle restricting the large-scale promotion of gasification technology.

[0003] Current treatment technologies for biomass tar are mainly divided into two categories: physical purification and chemical conversion. Physical purification methods reduce the tar content in biomass gas by separating tar from the gasified gas and transferring it to the condensate phase. These methods primarily include cyclone separation, wet purification, and dry purification. However, the main drawback of these methods is that they only separate the tar without further conversion and utilization, resulting in the ineffective use of the energy contained in the tar and generating secondary pollution, thus reducing the overall energy efficiency of the gasification process. Chemical conversion, on the other hand, uses high temperatures or catalysts to chemically react the tar in the gasified gas, degrading it into smaller molecules such as H2 and CO, further reducing its content and increasing the overall energy efficiency of the biomass gasification process. Specific methods include high-temperature pyrolysis and catalytic cracking. Although chemical conversion solves the tar conversion problem to some extent, its application is limited by high technical requirements. For example, high-temperature pyrolysis typically requires reaction temperatures exceeding 1200℃ and long reaction times. While catalytic cracking technology lowers the reaction temperature, issues such as catalyst activity, stability, selectivity, and recovery performance remain major bottlenecks for its widespread application.

[0004] The prior art, disclosed in CN114272858B, is a plasma catalytic system and method for efficient conversion of biomass tar. It uses a conical plasma reactor to achieve biomass tar conversion based on the principle of dielectric barrier discharge. In this reactor, the catalyst is placed on a flow equalization plate, which blocks part of the gas flow. Therefore, a large gas flow rate is required to achieve a better fluidization effect. However, a large flow rate will reduce the residence time of the material to be treated in the plasma region, affecting the overall reaction effect. Summary of the Invention

[0005] 1. The technical problem to be solved:

[0006] To address the aforementioned technical problems, this invention provides a device for converting biomass tar using a plasma multi-mode coupled catalyst. This device employs both DC and AC power supply for driving and combines fluidized bed and packed bed modes to couple the catalyst, thereby improving the overall reaction efficiency and ensuring sufficient contact between the tar and the plasma. This enables rapid and efficient tar treatment while also improving the operability and economy of the tar treatment process.

[0007] 2. Technical Solution:

[0008] A device for converting biomass tar using a plasma multimode coupled catalyst, characterized in that it includes a plasma reactor; the plasma reactor includes a coaxial DBD bulk discharge structure and a structured catalyst channel discharge structure; wherein the coaxial DBD bulk discharge structure includes an AC high-voltage electrode rod, a dielectric tube, and a ground electrode; the structured catalyst channel discharge structure includes a structured catalyst, catalyst particles, a DC high-voltage electrode, and an AC high-voltage electrode; the specific connections of the above structures are as follows:

[0009] The AC high-voltage electrode rod is coaxially disposed within the inner cavity of the dielectric tube; the upper end of the AC high-voltage electrode is connected to the high-voltage end of the AC power supply via a wire; a sealing ring structure is provided between the upper end of the AC high-voltage electrode rod and the dielectric tube to achieve a fixed and sealed connection between the two; a coaxial plug is also provided between the middle position of the AC high-voltage electrode rod and the inner wall of the dielectric tube; the lower end of the high-voltage electrode is suspended above the upper surface of the structural catalyst; the ground electrode is a cylindrical metal mesh structure, sleeved on the lower outer surface of the dielectric tube; the structural catalyst is cylindrical, fixed within the inner cavity of the dielectric tube, and its interior is honeycomb-shaped, with a DC high-voltage electrode fixedly connected to its lower surface; the upper surface of the structural catalyst is flush with the lower edge of the ground electrode; the DC high-voltage electrode is a disc with a diameter slightly smaller than that of the structural catalyst, and its upper surface is fixedly connected to the structural catalyst; the interior of the DC high-voltage electrode is mesh-like, and it is connected to the DC high-voltage power supply outward via a wire; the catalyst particles are placed within the inner cavity of the dielectric tube; the upper end of the dielectric tube is provided with an outlet, and the lower end is provided with an inlet pipe structure; The intake pipe structure includes a connected intake rigid pipe and a flexible pipe. The upper end of the intake rigid pipe is fixedly connected to the lower surface of the DC high voltage electrode, and can simultaneously fix the DC high voltage electrode and the structural catalyst. The lower end of the intake rigid pipe is connected to the gas source and the gas to be treated through the flexible pipe.

[0010] When the plasma reactor is energized, the AC high-voltage electrode rod, the dielectric tube, and the ground electrode form a coaxial DBD body discharge within the inner cavity of the dielectric tube. Under the combined action of AC and DC electric fields, the particulate catalyst particles and the structured catalyst within the inner cavity of the dielectric tube form a voltage difference between the upper and lower ends of the structured catalyst, thus creating a discharge within the structured catalyst channel. Simultaneously, the plasma-activated gas flowing upward from the structured catalyst causes the catalyst particles to fluidize, and the interaction between the catalyst and the plasma is achieved in conjunction with the coaxial DBD body discharge.

[0011] Furthermore, the medium tube is a quartz medium tube, and its lower end air inlet pipe structure is also provided with an outlet hole for passing wires.

[0012] Furthermore, the distance between the lower end of the AC high-voltage electrode rod and the upper surface of the structural catalyst is 1~2 mm.

[0013] Furthermore, the sealing ring structure is a sealing ring made of polytetrafluoroethylene material, specifically consisting of a first, second, and third sealing ring connected sequentially from top to bottom with threads; wherein the AC high-voltage electrode rod is fixedly sleeved at the center of the first sealing ring; the upper end of the third sealing ring is fixedly connected to the second sealing ring by threads, and the lower end is fixedly sleeved to the outer wall of the upper end of the dielectric tube; the AC high-voltage electrode rod extends into the inner cavity of the dielectric tube after passing through the through hole of the central axis of the second and third sealing rings.

[0014] Furthermore, the medium tube is a quartz medium tube with a length of 160mm~220mm, an outer diameter of 12mm~19mm, an inner diameter of 10mm~16mm, and a wall thickness of 1.0~1.5mm; its air inlet has an outer diameter of 5~8mm and a wall thickness of 0.8~1.6mm.

[0015] Furthermore, the high-voltage electrode is made of stainless steel or a tungsten rod with a diameter of 2-4 mm.

[0016] Furthermore, the structured catalyst has a diameter of 10 mm to 16 mm, a height of 8 mm to 20 mm, and a honeycomb pore size of 0.08-0.25 mm.

[0017] Furthermore, it also includes a high-pressure gas cylinder, a pressure reducing valve, a flow meter, a high-precision liquid injection pump, a heating furnace, a condenser, and a gas collection bag; the high-pressure gas cylinder, pressure reducing valve, flow meter, high-precision liquid injection pump, and heating furnace are connected in sequence, the heating furnace is connected to the gas inlet of the plasma reactor; the gas outlet of the plasma reactor is connected to the condenser, and the gas collection bag is connected to the condenser.

[0018] 3. Beneficial effects:

[0019] (1) The device for converting biomass tar using plasma multimode coupled catalyst provided by this method is an AC electric field formed between the AC high voltage electrode and the ground electrode in a coaxial DBD plasma reactor, which generates coaxial DBD discharge. An alternating potential difference is formed between the DC high voltage electrode and the AC high voltage electrode. Since catalyst particles are placed on the structured catalyst and there is an air layer of 1-2 mm on the surface of the high voltage AC electrode and the structured catalyst, a stable discharge plasma can be formed in the honeycomb structured catalyst channel under the action of the alternating electric field, forming a plasma-filled catalytic system. The gas flowing out of the honeycomb structured catalyst is not only activated by the plasma, but also makes the catalyst particles placed on the surface of the honeycomb structured catalyst in a fluidized state. Therefore, this method increases the discharge area and prolongs the contact time between the reaction gas and the plasma, while also enhancing the contact time and interaction between the plasma and the catalyst, which is beneficial to the generation of synergistic effect between the plasma and the catalyst.

[0020] (2) The method provides a device for converting biomass tar using a plasma multimode coupled catalyst. In the plasma reactor, a DC power supply is used to generate a stable electric field, while an AC power supply provides an alternating electric field. Under the superposition of these two electric fields, a stable plasma discharge is formed in the pores of the honeycomb structure catalyst and inside the coaxial DBD reactor, forming two plasma coupled catalyst systems: a filled system and a fluidized system. This increases the overall discharge path, and the interaction between the catalyst and the plasma is also enhanced.

[0021] (3) The plasma reactor provided by this method can realize a segmented packed bed plasma catalytic system. In this reactor, under the drive of an AC source, the high-voltage electrode, dielectric tube, and ground electrode form a coaxial DBD body discharge. The catalyst particles stacked on the top of the honeycomb structure catalyst have a large dielectric constant. By superimposing a DC high voltage on the mesh electrode, an alternating potential difference can be formed at the upper and lower ends of the honeycomb structure catalyst under the combined action of the AC high voltage electrode and the DC high voltage electrode, thereby forming a stable discharge plasma in the pores of the honeycomb structure catalyst. At this time, the honeycomb structure catalyst is directly placed in the discharge region of the plasma, forming a typical segmented packed bed plasma catalytic system.

[0022] (4) The plasma reactor provided by this method can also realize a plasma catalytic system in fluidized bed mode; by controlling the gas flow rate of the inlet pipe, the catalyst particles placed on the honeycomb structure catalyst can be in a fluidized state, forming a typical fluidized bed plasma catalytic system with the coaxial DBD body discharge.

[0023] (5) The plasma reactor in this method combines fluidized bed and packed bed modes to couple the catalyst to improve the overall reaction efficiency. When the reactant atmosphere passes through the honeycomb structure catalyst channel, it will be activated by the discharge plasma formed inside it. Subsequently, when the gas comes into contact with the small catalyst particles, it will have higher reactivity, promote the interaction between the catalyst and the plasma, and thus enhance their synergistic effect.

[0024] In summary, this method, by adjusting the electrode structure design and excitation mode, and combining honeycomb structure catalysts with traditional catalyst particles, forms multiple coupling modes between plasma and catalyst. While increasing the discharge path, it also strengthens the interaction between catalyst and plasma, which is conducive to the generation of synergistic effects between plasma and catalyst, thereby improving the overall conversion efficiency and performance. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall apparatus of the plasma multimode coupled catalyst for converting biomass tar according to the present invention.

[0026] Figure 2 This is an overall external view of the plasma reactor in this invention;

[0027] Figure 3 This is an exploded view of the plasma reactor in this invention;

[0028] Figure 4 This is a schematic diagram of the media tube of the plasma reactor in this invention;

[0029] Figure 5 This is an overall schematic diagram of the sealing structure in this invention;

[0030] Figure 6 This is a rendering of a specific embodiment.

[0031] Reference numerals: 1. Plasma reactor; 2. AC high-voltage electrode rod; 3. Medium tube; 4. Ground electrode; 5. Structural catalyst; 6. Catalyst particles; 7. DC high-voltage electrode; 8. Sealing ring structure; 9. Coaxial plug; 11. Gas outlet; 12. Gas inlet pipe structure; 13. Cable outlet; 14. First sealing ring; 15. Second sealing ring; 16. Third sealing ring; 17. Wire; 18. High-pressure gas cylinder; 19. Pressure reducing valve; 20. Flow meter; 21. High-precision liquid injection pump; 22. Heating furnace; 23. Condensation device; 24. Gas collection bag. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings.

[0033] As attached Figure 1 To be continued Figure 5As shown, a device for converting biomass tar using a plasma multimode coupled catalyst is characterized by comprising a plasma reactor 1; the plasma reactor includes a coaxial DBD body discharge structure and a structured catalyst channel discharge structure; wherein the coaxial DBD body discharge structure includes an AC high-voltage electrode rod 2, a dielectric tube 3, and a ground electrode 4; the structured catalyst channel discharge structure includes a structured catalyst 5, catalyst particles 6, a DC high-voltage electrode, and an AC high-voltage electrode 7; the specific connections of the above structures are as follows:

[0034] The AC high-voltage electrode rod is coaxially disposed within the inner cavity of the dielectric tube; the upper end of the AC high-voltage electrode is connected to the high-voltage terminal of the AC power supply via a wire; a sealing ring structure 8 is provided between the upper end of the AC high-voltage electrode rod and the dielectric tube to achieve a fixed and sealed connection between the two; a coaxial plug 9 is also provided between the middle position of the AC high-voltage electrode rod and the inner wall of the dielectric tube; the lower end of the high-voltage electrode is suspended above the upper surface of the structural catalyst; the ground electrode is a cylindrical metal mesh structure, sleeved on the lower outer surface of the dielectric tube; the structural catalyst is cylindrical, fixed within the inner cavity of the dielectric tube, and its interior is honeycomb-shaped, with a DC high-voltage electrode fixedly connected to its lower surface; the structural catalyst... The upper surface is flush with the lower edge of the ground electrode; the DC high-voltage electrode is a disk with a diameter slightly smaller than that of the structural catalyst, and the upper surface of the disk is fixedly connected to the structural catalyst; the interior of the DC high-voltage electrode is mesh-like and connected to the DC high-voltage power supply through wires; the catalyst particles are placed in the inner cavity of the medium tube; the upper end of the medium tube is provided with an outlet hole 11, and the lower end is provided with an inlet pipe structure 12; the inlet pipe structure includes a connected hard inlet pipe and a soft pipe, the upper end of the hard inlet pipe is fixedly connected to the lower surface of the DC high-voltage electrode, and can simultaneously fix the DC high-voltage electrode and the structural catalyst; the lower end of the hard inlet pipe is connected to the gas source and the gas to be treated through the soft pipe;

[0035] When the plasma reactor is energized, the AC high-voltage electrode rod, the dielectric tube, and the ground electrode form a coaxial DBD body discharge within the inner cavity of the dielectric tube. Under the combined action of AC and DC electric fields, the particulate catalyst particles and the structured catalyst within the inner cavity of the dielectric tube form a voltage difference between the upper and lower ends of the structured catalyst, thus creating a discharge within the structured catalyst channel. Simultaneously, the plasma-activated gas flowing upward from the structured catalyst causes the catalyst particles to fluidize, and the interaction between the catalyst and the plasma is achieved in conjunction with the coaxial DBD body discharge.

[0036] Furthermore, the medium tube is a quartz medium tube, and its lower end air inlet pipe structure is also provided with an outlet hole 13 for passing through the wire 17.

[0037] Furthermore, the distance between the lower end of the AC high-voltage electrode rod and the upper surface of the structural catalyst is 1~2 mm.

[0038] Furthermore, the sealing ring structure is a sealing ring made of polytetrafluoroethylene material, specifically consisting of a first, second, and third sealing ring connected sequentially from top to bottom with threads; wherein the center position of the first sealing ring 14 is fixedly sleeved with an AC high-voltage electrode rod; the upper end of the third sealing ring 16 is fixedly connected to the second sealing ring 15 by threads, and the lower end is fixedly sleeved to the outer wall of the upper end of the dielectric tube; the AC high-voltage electrode rod extends into the inner cavity of the dielectric tube after passing through the through hole of the central axis of the second and third sealing rings.

[0039] Furthermore, the medium tube is a quartz medium tube with a length of 160mm~220mm, an outer diameter of 12mm~19mm, an inner diameter of 10mm~16mm, and a wall thickness of 1.0~1.5mm; its air inlet has an outer diameter of 5~8mm and a wall thickness of 0.8~1.6mm.

[0040] Furthermore, the high-voltage electrode is made of stainless steel or a tungsten rod with a diameter of 2-4 mm.

[0041] Furthermore, the structured catalyst has a diameter of 10 mm to 16 mm, a height of 8 mm to 20 mm, and a honeycomb pore size of 0.08-0.25 mm.

[0042] Furthermore, it also includes a high-pressure gas cylinder 18, a pressure reducing valve 19, a flow meter 20, a high-precision liquid injection pump 21, a heating furnace 22, a condensing device 23, and a gas collection bag 24; the high-pressure gas cylinder, pressure reducing valve, flow meter, high-precision liquid injection pump, and heating furnace are connected in sequence, the heating furnace is connected to the gas inlet of the plasma reactor; the gas outlet of the plasma reactor is connected to the condensing device, and the gas collection bag is connected to the condensing device. Specific implementation examples:

[0044] As attached Figure 1 The diagram illustrates the entire process of treating biomass tar using this device. During treatment, the AC high-voltage electrode rod is connected to the high-voltage terminal of the AC power supply, and the ground electrode is grounded. The DC high-voltage electrode is connected to the positive terminal of the DC power supply, and the ground electrode of the DC power supply is also grounded. A high-pressure gas cylinder contains N2. When the device is operating, the cylinder is opened, and the gas is blown into the plasma reactor along the gas pipe. A pressure reducing valve prevents backflow, and a flow meter monitors the gas flow rate in real time. A high-precision liquid injection pump contains untreated liquid tar. During operation, the heater is turned on, and after reaching the set temperature, the tar storage bottle is opened, and the tar is pushed into the heater. As the tar enters the heater, the liquid tar is vaporized in a short time and blown into the high-voltage discharge chamber of the plasma reactor along with the gas flow through the inlet pipe. After a period of reaction, the outlet valve is opened, and the treated gas enters the gas collection bag along with the gas flow.

[0045] like Figures 2 to 4 As shown, during operation, the plasma reactor allows reactant gases to enter through the inlet pipe. Under the combined action of the plasma and catalyst, the tar undergoes cracking and transformation, generating syngas or small-molecule hydrocarbon gases which are then discharged through the outlet. These gases can be further collected or used in other industrial processes. The design of this device achieves excellent coupling between plasma and catalyst, facilitating synergistic effects. Combining fluidized bed and packed bed modes, it efficiently and stably processes biomass tar, reducing its pollution and converting it into valuable chemicals.

[0046] As attached Figure 2 As shown, this reactor is used for the treatment of biomass tar. It is driven by both DC and AC power sources and combines fluidized bed and packed bed modes to couple catalysts to improve overall reaction efficiency. An AC power source is connected between the AC high-voltage electrode and the ground electrode, generating a bulk dielectric barrier discharge through an alternating electric field. Under the superposition of the DC high-voltage electrode and the AC electric field, an alternating electric field is formed at both ends of the honeycomb catalyst, generating discharge plasma, increasing the discharge area, and prolonging the contact time between the reactant gas and the plasma. The DC power source generates a stable electric field, while the AC power source provides an alternating electric field, increasing the discharge length within the reactor, strengthening the interaction between the catalyst and the plasma, and thus improving the plasma's reactivity and efficiency. This device combines fluidized bed and packed bed modes: the honeycomb catalyst generates plasma in the channels under the excitation power source, thus forming a packed bed plasma system, allowing the plasma to contact the catalyst surface and produce a synergistic effect. The catalyst particles inside the reactor can form a fluidized state under the action of airflow. At the same time, the coaxial reactor can generate a stable volume discharge under the drive of the AC source, ensuring good contact between the catalyst and the plasma, and stimulating more active sites on the catalyst surface. This process has better heat and mass transfer efficiency of the reactants, which is beneficial to promoting the conversion of tar components. 17 in the figure represents the current-carrying wire.

[0047] To verify the practicality of this device, a comparison was made between the reactor of this device and a conventional conical reactor based on methane dry reforming. During the comparison, a flow meter was used to control the gas flow rate in real time, ensuring that the total flow rate of CH4 and CO2 was 300 ml / min and the volume ratio of CH4 to CO2 was 1:1. The reaction effects were analyzed and compared, and the overall results are as follows: Figure 6 As shown in the figure, Type a represents the existing conical coaxial DBD reactor, and Type b represents the reactor structure disclosed in this scheme. It can be clearly seen from the figure that, under the same operating conditions, the reactor structure proposed in this scheme achieves better reaction results.

[0048] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims of this application.

Claims

1. A device for plasma multimode coupled catalyst conversion of biomass tar, characterized in that: Includes a plasma reactor; the plasma reactor includes a coaxial DBD body discharge structure and a structured catalyst channel internal discharge structure; The coaxial DBD body discharge structure includes an AC high-voltage electrode rod, a dielectric tube, and a ground electrode; the structured catalyst channel discharge structure includes a structured catalyst, catalyst particles, a DC high-voltage electrode, and an AC high-voltage electrode; the specific connections of the above structures are as follows: the AC high-voltage electrode rod is coaxially disposed in the inner cavity of the dielectric tube; the upper end of the AC high-voltage electrode is connected to the high-voltage end of the AC power supply via a wire; a sealing ring structure is provided between the upper end of the AC high-voltage electrode rod and the dielectric tube to achieve a fixed and sealed connection between the two; a coaxial plug is also provided between the middle position of the AC high-voltage electrode rod and the inner wall of the dielectric tube; the lower end of the high-voltage electrode is suspended to the upper surface of the structured catalyst; the ground electrode is a cylindrical metal mesh structure, sleeved on the lower outer surface of the dielectric tube; the structured catalyst is... The catalyst is cylindrical and fixed inside the media tube. Its interior is honeycomb-shaped, and its lower surface is fixedly connected to a DC high-voltage electrode. The upper surface of the structural catalyst is flush with the lower edge of the ground electrode. The DC high-voltage electrode is a disk with a diameter slightly smaller than that of the structural catalyst, and its upper surface is fixedly connected to the structural catalyst. The interior of the DC high-voltage electrode is mesh-like and connected to a DC high-voltage power supply via wires. The catalyst particles are placed inside the media tube. The upper end of the media tube has an outlet, and its lower end has an inlet pipe structure. The inlet pipe structure includes a connected rigid inlet pipe and a flexible pipe. The upper end of the rigid inlet pipe is fixedly connected to the lower surface of the DC high-voltage electrode, simultaneously fixing the DC high-voltage electrode and the structural catalyst. The lower end of the rigid inlet pipe is connected to a gas source and the gas to be treated via a flexible pipe. When the plasma reactor is energized, the AC high-voltage electrode rod, the dielectric tube, and the ground electrode form a coaxial DBD body discharge within the inner cavity of the dielectric tube. Under the combined action of AC and DC electric fields, the particulate catalyst particles and the structured catalyst within the inner cavity of the dielectric tube form a voltage difference between the upper and lower ends of the structured catalyst, thus creating a discharge within the structured catalyst channel. Simultaneously, the plasma-activated gas flowing upward from the structured catalyst causes the catalyst particles to fluidize, and the interaction between the catalyst and the plasma is achieved in conjunction with the coaxial DBD body discharge.

2. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 1, characterized in that: The medium tube is a quartz medium tube, and its lower end air inlet pipe structure is also provided with an outlet hole for passing wires.

3. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 1, characterized in that: The distance between the lower end of the AC high-voltage electrode rod and the upper surface of the structural catalyst is 1-2 mm.

4. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 1, characterized in that: The sealing ring structure is a sealing ring made of polytetrafluoroethylene material, specifically consisting of a first, second, and third sealing ring connected sequentially from top to bottom with threads; wherein the AC high-voltage electrode rod is fixedly sleeved at the center of the first sealing ring; the upper end of the third sealing ring is fixedly connected to the second sealing ring by threads, and the lower end is fixedly sleeved to the outer wall of the upper end of the medium tube; the AC high-voltage electrode rod extends into the inner cavity of the medium tube after passing through the through hole of the central shaft of the second and third sealing rings.

5. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 1, characterized in that: The medium tube is a quartz medium tube with a length of 160mm to 220mm, an outer diameter of 12mm to 19mm, an inner diameter of 10mm to 16mm, and a wall thickness of 1.0mm to 1.5mm; its air inlet has an outer diameter of 5mm to 8mm and a wall thickness of 0.8mm to 1.6mm.

6. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 5, characterized in that: The high-voltage electrode is made of stainless steel or tungsten rod, with a diameter of 2-4 mm.

7. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 6, characterized in that: The structured catalyst has a diameter of 10 mm to 16 mm, a height of 8 mm to 20 mm, and a honeycomb pore size of 0.08-0.25 mm.

8. The apparatus for converting biomass tar using a plasma multimode coupled catalyst according to claim 1, characterized in that: It also includes a high-pressure gas cylinder, a pressure reducing valve, a flow meter, a high-precision liquid injection pump, a heating furnace, a condenser, and a gas collection bag; the high-pressure gas cylinder, pressure reducing valve, flow meter, high-precision liquid injection pump, and heating furnace are connected in sequence, the heating furnace is connected to the gas inlet of the plasma reactor; the gas outlet of the plasma reactor is connected to the condenser, and the gas collection bag is connected to the condenser.

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