Plasma resonance-monatomic catalysis synergistic method and system for preparing low-carbon olefin based on biomass microwave catalytic cracking

Abstract

The invention provides a plasma resonance-monatomic catalysis synergistic method and system for preparing low-carbon olefin based on biomass microwave catalytic cracking, and relates to the field of new energy and green chemical industry. According to the plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefin based on biomass microwave catalytic cracking, biomass raw materials are pretreated to obtain a first intermediate, and the biomass raw materials comprise lignocellulose raw materials, oil crop raw materials and energy plant raw materials. According to the plasma resonance-monatomic catalysis synergistic method and system for preparing low-carbon olefin based on biomass microwave catalytic cracking, the core-shell structure catalyst has good regeneration performance, so that the catalyst can be effectively recycled in a long-time operation process; the problem of inactivation of a traditional catalyst caused by carbon deposition or sintering is avoided, the production cost can be reduced while the reaction efficiency is improved, and the requirement of sustainable development is met.

Description

Technical Field

[0001] This invention relates to the fields of new energy and green chemical technology, specifically to a plasma resonance-single atom catalytic synergistic method and system for preparing low-carbon olefins based on microwave catalytic cracking of biomass. Background Technology

[0002] Low-carbon olefins are important raw materials for modern chemical industries. Traditional production methods rely on naphtha cracking, methanol-to-olefins (MTO), and coal chemical processes, but these methods suffer from high energy consumption, large carbon emissions, and heavy environmental burdens. Under the "dual-carbon goal" (referring to carbon emission reduction and carbon sequestration), biomass, due to its wide availability and high renewability, is considered an important alternative. Existing technologies mainly achieve biomass conversion through pyrolysis and catalytic cracking, but traditional heating methods are inefficient and produce complex byproducts. To improve product distribution, researchers have introduced metal catalysts or molecular sieves, but these generally suffer from carbon deposition, deactivation, and insufficient reaction stability. In recent years, microwave heating has attracted attention due to its high energy transfer efficiency. Microwave plasma can rapidly generate high-energy electrons and free radicals, accelerating biomass cracking. Meanwhile, single-atom catalysts show potential in reaction regulation due to their high utilization rate and unique electronic structure. Some studies have attempted to combine these two methods, but the overall effect remains limited.

[0003] Existing microwave catalytic cracking processes for biomass suffer from significant shortcomings in energy utilization and product control. The lack of effective synergy between plasma-active species and catalyst active sites leads to uneven energy transfer, increased side reactions, and low yields and poor stability of low-carbon olefins. During long-term operation, the catalyst is prone to carbon deposition, sintering, and structural degradation, making it difficult to maintain high performance. Therefore, how to achieve precise control of energy and reaction pathways through the synergistic effect of plasma resonance and single-atom catalytic sites has become a crucial issue that urgently needs to be addressed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a plasma resonance-single-atom catalytic synergistic method and system for preparing low-carbon olefins based on microwave catalytic pyrolysis of biomass. This method solves the problem of how to utilize the synergistic effect of plasma resonance pyrolysis reaction and single-atom catalyst to achieve efficient preparation of low-carbon olefins, improve energy utilization, product selectivity, and catalyst cycle stability.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a plasma resonance-single atom catalytic synergistic method for preparing low-carbon olefins based on microwave catalytic cracking of biomass, comprising: S1, pretreating biomass raw materials to obtain a first intermediate, wherein the biomass raw materials include lignocellulosic raw materials, oil crop raw materials and energy plant raw materials.

[0006] S2, Constructing core-shell structured catalysts.

[0007] S3. The first intermediate and the core-shell structured catalyst are placed in a dual-frequency microwave reactor to carry out a plasma resonance pyrolysis reaction, and the second intermediate is obtained through the plasma resonance pyrolysis reaction.

[0008] S4. The second intermediate is selectively separated to obtain low-carbon olefin pyrolysis product.

[0009] S5. The core-shell structured catalyst is regenerated, and the core-shell structured catalyst can be recycled after the regeneration treatment.

[0010] Preferably, the pretreatment includes hydrothermal treatment of the lignocellulosic raw material to remove some lignin components, cell wall disruption treatment of the oilseed crop raw material to release the internal organic matter of the oilseed crop raw material, and structural loosening treatment of the energy plant raw material. The energy plant raw material is a gene-edited modified variety with a lignin content ≤8% to improve the uniformity of subsequent pyrolysis reactions.

[0011] Preferably, the construction process of the core-shell structured catalyst is as follows: S21. Using ZSM-5 molecular sieve as the core support, the core support is dispersed in a solution containing iron salt, and the solution is subjected to photochemical deposition under ultraviolet light to form a first catalytic precursor.

[0012] S22. The first catalytic precursor is placed in a sol-gel reaction system to perform an encapsulation reaction to generate a mesoporous silica shell, and the first catalytic precursor is used to produce a second catalytic precursor through the encapsulation reaction.

[0013] S23. The second catalytic precursor is placed in a reducing atmosphere for heat treatment to obtain the core-shell structured catalyst.

[0014] Preferably, the main frequency of the dual-frequency microwave reactor is 2.45 GHz ± 50 MHz, and the auxiliary frequency is 915 MHz ± 20 MHz. The reaction atmosphere of the plasma resonance pyrolysis reaction is argon and hydrogen, with a volume ratio of argon to hydrogen of 9:1. The reaction pressure of the plasma resonance pyrolysis reaction is 0.1 MPa–0.5 MPa, and the microwave power is 5 kW–10 kW. The 2.45 GHz microwave is mainly used to excite molecular dipole rotation, and the 915 MHz microwave is used to induce... Electron resonance at single-atom sites, with a resonance frequency range of 905MHz–925MHz.

[0015] Preferably, the selective separation process involves separating the second intermediate using an MFI-type molecular sieve membrane. The low-carbon olefin, wherein the pore size of the MFI type molecular sieve membrane is 0.55 nm.

[0016] Preferably, the plasma resonance pyrolysis reaction is detected by time-of-flight mass spectrometry (TOF-MS) as a detector, and the resolution of the TOF-MS is ≥30000.

[0017] Preferably, the regeneration process is carried out in an oxygen-containing dilution gas atmosphere, the regeneration process is carried out at a temperature of 550°C for a time of two hours, and the oxygen-containing dilution gas includes oxygen and nitrogen, with the mass ratio of oxygen to nitrogen being 1:19.

[0018] A plasma resonance-single-atom catalytic synergistic system for the preparation of low-carbon olefins based on microwave catalytic cracking of biomass includes: The raw material pretreatment unit is used to perform hydrothermal treatment and pulverization on biomass raw materials to obtain a first intermediate. The raw material pretreatment unit includes a hydrothermal reactor and a pulverizing device.

[0019] A catalyst preparation unit is used to prepare core-shell structured catalysts. The catalyst preparation unit includes a photochemical deposition device, a sol-gel coating device, and a high-temperature reduction furnace.

[0020] A dual-frequency microwave catalytic pyrolysis reaction unit is used to perform a plasma resonance pyrolysis reaction on the first intermediate to obtain a second intermediate. The reaction unit includes a dual-frequency microwave generator and a reaction chamber. The dual-frequency microwave generator generates microwaves at two frequencies: 2.45 GHz and 915 MHz.

[0021] The product separation and monitoring unit is used to separate the second intermediate in real time to obtain low-carbon olefin pyrolysis products. The separation and monitoring unit includes a molecular sieve membrane separation device and an in-situ mass spectrometer.

[0022] A catalyst regeneration unit is used to regenerate the core-shell structure catalyst. The catalyst regeneration unit includes a high-temperature roasting furnace and an atmosphere control device.

[0023] This invention provides a plasma resonance-single-atom catalytic synergistic method and system for the preparation of low-carbon olefins based on microwave catalytic pyrolysis of biomass. It has the following beneficial effects: The present invention provides a plasma resonance-single-atom catalytic synergistic method and system for biomass microwave catalytic cracking. Through the synergistic effect of plasma resonance and single-atom catalyst, the energy utilization rate of the reaction is improved, effectively increasing the yield and selectivity of low-carbon olefins. By precisely controlling the energy and reaction pathway, the cracking reaction process is optimized, side reactions are reduced, and the quality and stability of the product are improved.

[0024] This plasma resonance-single atom catalytic synergistic method and system for preparing low-carbon olefins based on microwave catalytic cracking of biomass employs a core-shell structure catalyst with excellent regeneration performance, enabling the catalyst to be effectively recycled during long-term operation. This avoids the deactivation problem caused by carbon deposition or sintering of traditional catalysts, and can improve reaction efficiency while reducing production costs, thus meeting the requirements of sustainable development. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the biomass raw material pretreatment process; Figure 2 This is a schematic diagram illustrating the preparation of a core-shell structured catalyst. Figure 3 This is a schematic diagram of low-carbon olefin separation and monitoring. Figure 4 This is a schematic diagram of a microwave catalytic cracking process. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 like Figure 1-4 As shown, this invention provides a plasma resonance-single-atom catalytic synergistic method for preparing low-carbon olefins based on microwave catalytic pyrolysis of biomass. The method includes: S1, pretreatment of biomass raw materials to obtain a first intermediate. The biomass raw materials include lignocellulosic raw materials, oilseed crop raw materials, and energy plant raw materials. The pretreatment includes hydrothermal treatment of the lignocellulosic raw materials to remove some lignin components; cell wall disruption treatment of the oilseed crop raw materials to release internal organic matter; and structural loosening treatment of the energy plant raw materials. The energy plant raw materials are gene-edited varieties with a lignin content ≤8% to improve the uniformity of subsequent pyrolysis reactions.

[0028] S2, Constructing core-shell structured catalysts.

[0029] The construction process of the core-shell structure catalyst is as follows: S21. Using ZSM-5 molecular sieve as the core support, the core support is dispersed in a solution containing iron salt, and the solution is photochemically deposited under ultraviolet light to form the first catalytic precursor.

[0030] S22. The first catalytic precursor is placed in a sol-gel reaction system to perform an encapsulation reaction to generate a mesoporous silica shell, and the first catalytic precursor encapsulates the second catalytic precursor.

[0031] S23. The second catalytic precursor is placed in a reducing atmosphere for heat treatment to obtain a core-shell structured catalyst.

[0032] S3. The first intermediate and the core-shell catalyst are placed in a dual-frequency microwave reactor for plasma resonance pyrolysis to obtain the second intermediate. The main frequency of the dual-frequency microwave reactor is 2.45 GHz ± 50 MHz, and the auxiliary frequency is 915 MHz ± 20 MHz. The reaction atmosphere for the plasma resonance pyrolysis reaction is argon and hydrogen, with a volume ratio of 9:1. The reaction pressure is 0.1 MPa–0.5 MPa, and the microwave power is 5 kW–10 kW. The 2.45 GHz microwave is mainly used to excite molecular dipole rotation, and the 915 MHz microwave is used to induce... Electron resonance at single-atom sites, with a resonance frequency range of 905MHz–925MHz.

[0033] S4. The second intermediate is selectively separated to obtain low-carbon olefin pyrolysis products. The selective separation is performed using an MFI-type molecular sieve membrane to separate the second intermediate. The pore size of the MFI type molecular sieve membrane for low-carbon olefins is 0.55 nm.

[0034] S5. The core-shell structured catalyst is regenerated and can be recycled. The regeneration process is carried out in an oxygen-containing dilution gas atmosphere at a temperature of 550°C for two hours. The oxygen-containing dilution gas includes oxygen and nitrogen, with a mass ratio of oxygen to nitrogen of 1:19.

[0035] A plasma resonance-single-atom catalytic synergistic system for the preparation of low-carbon olefins based on microwave catalytic cracking of biomass includes: The raw material pretreatment unit is used to perform hydrothermal treatment and pulverization on biomass raw materials to obtain a first intermediate. The raw material pretreatment unit includes a hydrothermal reactor and a pulverizing device.

[0036] Hydrothermal reactor: Used for hydrothermal treatment of biomass feedstock. Specifically, the reaction is carried out at a temperature of 150℃ to 250℃, using a pressure of 1MPa to 2MPa, for a reaction time of 2 to 4 hours.

[0037] Crushing unit: Used to crush the hydrothermally treated biomass feedstock to ensure that its particle size is suitable for the subsequent pyrolysis process. The crushing unit adopts a wet crushing method, using high-speed rotating blades or airflow to crush the raw material to a particle size of 100 to 200 mesh.

[0038] The catalyst preparation unit is used to prepare core-shell structured catalysts. The catalyst preparation unit includes a photochemical deposition device, a sol-gel coating device, and a high-temperature reduction furnace.

[0039] Photochemical deposition apparatus: This apparatus is used to adsorb iron salt solution onto ZSM-5 molecular sieves and initiate a photochemical reaction under ultraviolet light irradiation. The intensity of the ultraviolet light is typically set to 10 mW / cm², and the irradiation time is 2 hours to ensure that the iron salt is uniformly deposited on the surface of the molecular sieve, forming the first catalytic precursor.

[0040] Sol-gel coating apparatus: A mesoporous silica shell is coated onto the surface of the first catalytic precursor. A hydrolysis reaction is performed using a mixture of tetraethoxysilane and water, reacting at room temperature for 6 hours to form a uniform silica coating layer. The coated catalytic precursor becomes the second catalytic precursor, ready for subsequent heat treatment.

[0041] High-temperature reduction furnace: Used for heat treatment of the second catalytic precursor in a reducing atmosphere. The process is typically carried out at 600°C, using hydrogen as the reducing atmosphere at a flow rate of 50 mL / min, for 4 hours, ultimately producing a product containing... Core-shell structured catalysts with single-atom catalytic sites.

[0042] The dual-frequency microwave catalytic pyrolysis reaction unit is used to perform a plasma resonance pyrolysis reaction on the first intermediate to obtain the second intermediate. The reaction unit includes a dual-frequency microwave generator and a reaction chamber. The dual-frequency microwave generator generates microwaves at two frequencies: 2.45 GHz and 915 MHz.

[0043] Dual-frequency microwave generator: This generator can simultaneously produce microwaves at two frequencies: 2.45 GHz and 915 MHz. The 2.45 GHz microwaves primarily excite the molecular dipole rotation, increasing the temperature of the reactants, while the 915 MHz microwaves are specifically designed to... Single-atom catalytic sites induce electronic resonance, enhancing the efficiency of the catalytic cracking reaction. The microwave power is adjustable from 5kW to 10kW and controlled by a microwave generator.

[0044] Reaction Chamber: The reaction chamber contains the first intermediate and the catalyst, providing a suitable environment for the cracking reaction. The reaction atmosphere within the chamber is argon and hydrogen in a volume ratio of 9:1, and the reaction pressure is controlled between 0.1 MPa and 0.5 MPa. The reaction results in the conversion of the first intermediate into a second intermediate, which is further separated into low-carbon olefins.

[0045] The product separation and monitoring unit is used to separate the second intermediate in real time to obtain low-carbon olefin pyrolysis products. The separation and monitoring unit includes a molecular sieve membrane separation device and an in-situ mass spectrometer.

[0046] Molecular sieve membrane separation device: Utilizing an MFI-type molecular sieve membrane for selective separation of the second intermediate to obtain low-carbon olefins. The pore size of the molecular sieve membrane is set to 0.55 nm, which effectively separates small-molecule low-carbon olefins while preventing larger byproducts from passing through.

[0047] In-situ mass spectrometry: During the separation process, the composition and concentration of the pyrolysis products are monitored by a mass spectrometer to ensure the high-purity production of low-carbon olefins. The mass spectrometer has a resolution of ≥30,000, enabling accurate determination of the molecular structure and content of the products and real-time adjustment of reaction conditions.

[0048] The catalyst regeneration unit is used to regenerate the core-shell structure catalyst. The catalyst regeneration unit includes a high-temperature roasting furnace and an atmosphere control device.

[0049] High-temperature calcination furnace: Catalyst regeneration involves calcination at 550℃ for 2 hours. This process removes surface carbon from the catalyst, restoring its catalytic activity.

[0050] Atmosphere control device: The regeneration process uses a diluted atmosphere containing nitrogen and oxygen, with a mass ratio of oxygen to nitrogen of 1:19, which can effectively remove harmful substances from the catalyst surface and prevent the catalyst from being over-oxidized during the regeneration process.

[0051] Example 2 This embodiment illustrates the construction process of a core-shell structured catalyst with excellent catalytic performance and stability.

[0052] S21. Using ZSM-5 molecular sieve as the core support, the core support is dispersed in a solution containing iron salt, and the solution is photochemically deposited under ultraviolet light to form the first catalytic precursor.

[0053] Kernel carrier selection and distribution: ZSM-5 molecular sieve was selected as the core support for the catalyst. ZSM-5 molecular sieve exhibits excellent acidity and structural stability, making it suitable for catalytic reactions. ZSM-5 molecular sieve powder was dispersed in a solution containing iron salts at a specific mass ratio, ensuring full contact between the molecular sieve core and the iron salt solution.

[0054] Photochemical deposition: The solution was exposed to ultraviolet light, typically at an intensity of 10 mW / cm², for 2 hours. Through photochemical deposition, iron ions were deposited on the surface of the ZSM-5 molecular sieve to form the first catalytic precursor. Photochemical deposition ensures uniform distribution of iron ions on the ZSM-5 surface, providing active sites for subsequent catalytic reactions.

[0055] S22. The first catalytic precursor is placed in a sol-gel reaction system to perform an encapsulation reaction to generate a mesoporous silica shell, and the first catalytic precursor encapsulates the second catalytic precursor.

[0056] Preparation of sol-gel reaction system: The first catalytic precursor was placed in a sol-gel reaction system for encapsulation. This system consisted of a mixture of tetraethoxysilane and water in a specific ratio. The reaction was carried out at room temperature for 6 hours to ensure uniform coating of the silica shell.

[0057] Package reaction: In the sol-gel reaction system, silica forms and coats the surface of the first catalytic precursor through hydrolysis and condensation reactions, generating a mesoporous silica shell. This process helps improve the stability of the catalyst and provides a larger surface area for the catalytic reaction.

[0058] Formation of catalytic precursors: After the encapsulation reaction, the resulting catalytic precursor is the second catalytic precursor, which has an outer mesoporous silica shell and a core of ZSM-5 molecular sieve and iron salt complex. S23. The second catalytic precursor is placed in a reducing atmosphere for heat treatment to obtain a core-shell structured catalyst.

[0059] Setting heat treatment conditions: The second catalytic precursor was heat-treated in a reducing atmosphere using hydrogen at a flow rate of 50 mL / min. The heat treatment temperature was set at 600 °C for 4 hours. This heat treatment effectively removed impurities within the silica shell and reduced the iron salt to the active phase. Single-atom catalytic site.

[0060] Final formation of the catalyst: After heat treatment, the resulting core-shell structured catalyst exhibits excellent catalytic performance. The ZSM-5 molecular sieve core provides structural support, while the mesoporous silica shell provides a stable external environment, and the iron single-atom sites play a crucial catalytic role in the reaction.

[0061] Example 3 This embodiment improves the yield and selectivity of low-carbon olefins by precisely controlling the reaction atmosphere, microwave power, and reaction pressure, and by utilizing the synergistic effect of plasma resonance and single-atom catalytic sites.

[0062] 1. Configuration of a dual-frequency microwave reactor Main and auxiliary frequency settings: The main frequency of the dual-frequency microwave reactor is set to 2.45 GHz ± 50 MHz to excite the dipole rotation of reactant molecules, thereby heating the reactants. The auxiliary frequency is 915 MHz ± 20 MHz, acting on the catalyst. Single-atom catalytic sites induce electronic resonance and promote pyrolysis reactions.

[0063] Microwave power: The microwave power is set to 8kW, which ensures uniform heating of the reactants and effectively stimulates the plasma reaction. The power range is 5kW to 10kW and can be adjusted according to the reaction progress.

[0064] 2. Reaction atmosphere and temperature settings Reaction Atmosphere: During the reaction, a mixture of argon and hydrogen is used, with a volume ratio of argon to hydrogen of 9:1. Argon acts as an inert gas to provide stability to the reaction environment, while hydrogen helps reduce side reactions and promotes the cracking process.

[0065] Reaction pressure: The operating pressure inside the reactor is controlled at 0.2 MPa. This pressure helps to maintain sufficient contact between the microwave and the reactants and catalyst, ensuring the smooth progress of the pyrolysis reaction.

[0066] 3. Pyrolysis reaction process In the reactor, the first intermediate and the core-shell catalyst jointly participate in the plasma resonance pyrolysis reaction: By exciting molecular dipoles with 2.45 GHz microwaves, the reactants are heated and decomposed. During the decomposition process, the energy of the microwaves breaks down the macromolecules in the biomass, generating small-molecule, low-carbon olefins.

[0067] The function of 915MHz microwave is to induce Electronic resonance at single-atom catalytic sites enhances catalyst activity. The resonance effect increases the rate of the cracking reaction and improves the efficiency of low-carbon olefin formation.

[0068] 4. Reactant transformation and intermediate formation The first intermediate, under microwave irradiation and synergistic effect with a catalyst, undergoes a cracking reaction to generate a second intermediate. The secondary products contain preliminary products of low-carbon olefins, some in a gaseous state and some in a liquid or solid state.

[0069] 5. Post-processing of the product Through microwave heating and plasma excitation, the pyrolysis products are effectively decomposed. The second intermediate will then be the target for subsequent selective separation, and further processing will yield lower-carbon olefins with higher purity.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on microwave catalytic pyrolysis of biomass, characterized in that, The method comprises the following steps: S1. Pre-treating a biomass raw material to obtain a first intermediate, wherein the biomass raw material comprises lignocellulosic raw material, oil crop raw material and energy plant raw material; S2. Constructing a core-shell structure catalyst; S3. Placing the first intermediate and the core-shell structure catalyst into a double-frequency microwave reactor to perform a plasma resonance cracking reaction, and obtaining a second intermediate through the plasma resonance cracking reaction; S4. Selectively separating and processing the second intermediate to obtain a low-carbon olefin cracking product; S5. Regenerating the core-shell structure catalyst, wherein the regenerated core-shell structure catalyst can be recycled.

2. The plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on biomass microwave catalytic cracking according to claim 1, characterized in that: The pre-treatment comprises hydrothermal treatment of the lignocellulosic raw material, cell wall crushing treatment of the oil crop raw material, and structure loosening treatment of the energy plant raw material, wherein the energy plant raw material is a genetically edited variety with a lignin content of less than or equal to 8%.

3. The plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on biomass microwave catalytic cracking according to claim 1, characterized in that: The construction process of the core-shell structure catalyst comprises the following steps: S21. Using ZSM-5 molecular sieve as an inner core carrier, dispersing the inner core carrier in a solution containing iron salt, and performing photochemical deposition of the solution under ultraviolet light to form a first catalytic precursor; S22. Placing the first catalytic precursor into a sol-gel reaction system to perform a wrapping reaction to generate a mesoporous silica shell layer, and obtaining a second catalytic precursor through the wrapping reaction of the first catalytic precursor; S23. Placing the second catalytic precursor into a reducing atmosphere to perform heat treatment to obtain the core-shell structure catalyst.

4. The plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on biomass microwave catalytic cracking according to claim 1, characterized in that: The double-frequency microwave reactor has a main frequency of 2.45 GHz ± 50 MHz and an auxiliary frequency of 915 MHz ± 20 MHz, the plasma resonance cracking reaction is performed in an argon and hydrogen atmosphere, the volume ratio of the argon to the hydrogen is 9:1, the reaction pressure of the plasma resonance cracking reaction is 0.1 MPa-0.5 MPa, and the microwave power is 5 kW-10 kW.

5. The plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on biomass microwave catalytic cracking according to claim 1, characterized in that: The selective separation treatment is performed by separating the second intermediate with an MFI-type molecular sieve membrane low carbon olefins, and the MFI-type molecular sieve membrane has a pore size of 0.55 nm.

6. The plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on biomass microwave catalytic pyrolysis according to claim 1, characterized in that: The plasma resonance cracking reaction is detected by a time-of-flight mass spectrometer as a detector, and the resolution of the time-of-flight mass spectrometer is greater than or equal to 30000.

7. The plasma resonance-monatomic catalysis synergistic method for preparing low-carbon olefins based on biomass microwave catalytic pyrolysis according to claim 1, characterized in that: The regeneration treatment is performed in an oxygen-containing dilution gas atmosphere, the temperature of the regeneration treatment is 550°C, the time of the regeneration treatment is two hours, the oxygen-containing dilution gas comprises oxygen and nitrogen, and the mass ratio of the oxygen to the nitrogen is 1:

19.

8. A plasma resonance-monatomic catalysis synergistic system for preparing low-carbon olefins based on microwave catalytic pyrolysis of biomass, characterized in that, The method comprises the following steps: A raw material pre-treatment unit for performing hydrothermal treatment and crushing treatment on a biomass raw material to obtain a first intermediate, wherein the raw material pre-treatment unit comprises a hydrothermal reaction kettle and a crushing device; A catalyst preparation unit for preparing a core-shell structure catalyst, wherein the catalyst preparation unit comprises a photochemical deposition device, a sol-gel coating device and a high-temperature reduction furnace; A double-frequency microwave catalytic cracking reaction unit for performing a plasma resonance cracking reaction on the first intermediate to obtain a second intermediate, wherein the reaction unit comprises a double-frequency microwave generator and a reaction cavity, and the double-frequency microwave generator generates microwaves with two frequencies of 2.45 GHz and 915 MHz. a product separation and monitoring unit for separating the second intermediate in real time to obtain a low-carbon olefin cracking product, the separation and monitoring unit comprising a molecular sieve membrane separation device and an in-situ mass spectrometer; a catalyst regeneration unit for regenerating the core-shell structure catalyst, the catalyst regeneration unit comprising a high-temperature calcination furnace and an atmosphere control device.

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