A multi-stage plasma-catalyst coupling method and device for efficient upgrading of biomass pyrolysis gas

Abstract

The present application belongs to the technical field of biomass energy conversion and solid waste resource utilization, and particularly relates to a multi-stage plasma-catalysis coupled biomass pyrolysis gas efficient upgrading method and device. The present application realizes efficient cracking of tar and optimization of gas components by constructing a multi-stage plasma-catalysis coupled reaction system, combining CO2 atmosphere regulation and control, and tar backflow circulation, so as to improve the gas calorific value and improve the system operation stability.

Description

Technical Field

[0001] This invention belongs to the field of biomass energy conversion and solid waste resource utilization technology, specifically relating to a multi-stage plasma-catalytic coupling method and apparatus for high-efficiency upgrading of biomass pyrolysis gas. Background Technology

[0002] With the energy structure shifting towards low-carbon development, biomass, as a renewable carbon resource, has significant application prospects in the pyrolysis and gasification of fuel gas and chemical feedstocks. Meanwhile, the large-scale generation of waste plastics such as low-density polyethylene (LDPE) has also brought serious environmental problems. The co-conversion of waste plastics with biomass to achieve resource utilization has become one of the current research hotspots.

[0003] In existing technologies, biomass pyrolysis gas typically contains a high proportion of tar, macromolecular hydrocarbons, and non-combustible components such as CO2, resulting in a low calorific value and susceptibility to coking and blockage during transportation and utilization. Traditional tar removal methods include physical separation, liquid washing, and high-temperature catalytic cracking, but these generally suffer from drawbacks such as high energy consumption, secondary pollution, or easy catalyst deactivation. In recent years, the co-pyrolysis of waste plastics and biomass has been explored. Through the synergistic effect between the hydrogen-rich components in the plastics and the oxygen-containing structures in the biomass, tar formation can be suppressed to some extent, but it still falls short of meeting the demand for high-quality fuel gas.

[0004] Dielectric barrier discharge (DBD) plasma technology, capable of generating high-energy electrons and various active particles under ambient pressure and relatively low temperatures, has been used to promote tar cracking and gas reforming. However, single-plasma treatment suffers from low energy utilization efficiency and poor reaction selectivity. Furthermore, traditional catalysts are prone to carbon deposition and deactivation in high-tar environments, affecting long-term stable operation. In addition, while existing research has attempted to couple plasma with catalysts, most employ simple series structures, failing to fully leverage the synergistic effect between plasma and catalysts. Insufficient consideration has also been given to reaction atmosphere control and tar recycling, leaving room for improvement in quality enhancement efficiency.

[0005] Therefore, there is an urgent need to develop a biomass and plastic co-thermal decomposition gasification method that can achieve multi-stage reaction regulation, deep coupling of plasma and catalyst, and take into account both reaction efficiency and catalyst stability, so as to improve gas quality and reduce tar content. Summary of the Invention

[0006] In view of this, the present invention provides a method and apparatus for high-efficiency quality improvement of biomass pyrolysis gas through multi-stage plasma-catalysis coupling. This method can overcome the problems of high tar content, low gas quality, insufficient plasma treatment efficiency, and easy carbon deposition and deactivation of catalysts in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a multi-stage plasma-catalysis coupled method for efficient upgrading of biomass pyrolysis gas, comprising the following steps: (1) Waste plastic containing low-density polyethylene is mixed with biomass raw materials and pyrolyzed under an inert atmosphere to generate primary pyrolysis gas; the primary pyrolysis gas contains tar components and combustible gas. (2) The primary pyrolysis gas is subjected to preliminary plasma pyrolysis in the primary plasma pyrolysis zone to obtain the gas after preliminary pyrolysis; the primary pyrolysis gas is subjected to preliminary plasma pyrolysis by non-thermal plasma generated by pulse-modulated dielectric barrier discharge in the primary plasma pyrolysis zone. (3) The gas after preliminary cracking is introduced into the plasma-catalytic coupling reaction zone for plasma-catalytic coupling reaction. Then the gas after reaction is cooled and separated to obtain hydrogen-rich gas and tar products. Some of the tar products are atomized and then subjected to plasma primary cracking and plasma-catalytic coupling reaction again to form a circulation path. The plasma-catalyst coupling reaction zone is equipped with an AAEMs-modified iron-based biochar catalyst; the AAEMs-modified iron-based biochar catalyst is distributed in the discharge gap between the electrodes in a discontinuous conductive structure; the plasma primary pyrolysis and the plasma-catalyst coupling reaction are carried out under CO2 gas conditions.

[0008] Preferably, the voltage of the pulse-modulated dielectric barrier discharge is 5~30 kV, the frequency is 1~50 kHz, and the duty cycle is 10%~90%.

[0009] Preferably, the temperature of the pyrolysis reaction is 600~700℃ and the time is 0.5~2h.

[0010] Preferably, the AAEMs-modified iron-based biochar catalyst is supported on a porous insulating support, so that the catalyst particles are spaced apart to form a discontinuous conductive path.

[0011] Preferably, the iron loading in the AAEMs-modified iron-based biochar catalyst is 5-15 wt%; the AAEMs are one or more of K, Na, Ca and Mg.

[0012] Preferably, the volumetric flow rate of CO2 accounts for 5% to 50% of the total volumetric flow rate of the pyrolysis gas obtained from the pyrolysis reaction.

[0013] Preferably, the tar products comprise 20% to 80% of the total separated tar.

[0014] Preferably, the tar products are atomized to form droplets with an average particle size of less than 100 μm.

[0015] Preferably, the preparation of the AAEMs-modified iron-based biochar catalyst includes the following steps: The biomass precursor is impregnated in a salt solution, and the resulting salt impregnated with biomass is pyrolyzed under a protective atmosphere to obtain the AAEMs-modified iron-based biochar catalyst; the salt solution includes iron salts and alkali metal / alkaline earth metal salts.

[0016] The present invention also provides a multi-stage plasma-catalysis coupled biomass pyrolysis gas high-efficiency quality improvement system, comprising a co-pyrolysis reactor, a plasma reactor, a condenser system, a gas-liquid separator and a tar collection tank connected in sequence; the tar collection tank and the plasma reactor are connected to form a loop; The plasma reactor includes a plasma primary pyrolysis zone and a plasma-catalytic coupling zone connected in sequence; the plasma-catalytic coupling zone is provided with an AAEMs-modified iron-based biochar catalyst; the AAEMs-modified iron-based biochar catalyst is distributed in the discharge gap between the electrodes in a discontinuous conductive structure.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) By co-pyrolyzing biomass and plastics, the hydrogen-rich properties of plastics are used to suppress the formation of tar precursors, thereby reducing tar content from the source; (2) By constructing a multi-level structure of plasma primary pyrolysis zone and plasma-catalytic coupling reaction zone, the graded pyrolysis and conversion of tar are realized, thereby improving reaction efficiency; (3) By using pulse-modulated DBD plasma, the electron energy distribution is optimized, thereby improving the selective pyrolysis efficiency of tar and reducing energy consumption; (4) By filling the plasma reaction zone with AAEMs-modified iron-based biochar catalyst with discontinuous conductive distribution, the spatial coupling of plasma and catalytic reaction is realized, thereby significantly enhancing the quality improvement effect; (5) By introducing CO2 gas, it is simultaneously involved in the dry reforming reaction and the gasification process of carbon on the catalyst surface, thereby realizing the synergistic process of reaction and catalyst regeneration; (6) By setting up a tar reflux system, the tar is atomized and fed back to the plasma reaction zone for secondary pyrolysis, thereby realizing the recycling of tar and significantly reducing system tar emissions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0019] Figure 1 The process flow diagram provided for this invention. Detailed Implementation

[0020] This invention provides a multi-stage plasma-catalysis coupled method for efficient upgrading of biomass pyrolysis gas, comprising the following steps: (1) Waste plastic containing low-density polyethylene is mixed with biomass raw materials and pyrolyzed under an inert atmosphere to generate primary pyrolysis gas; the primary pyrolysis gas contains tar components and combustible gas. (2) The primary pyrolysis gas is subjected to preliminary plasma pyrolysis in the primary plasma pyrolysis zone to obtain the gas after preliminary pyrolysis; the primary pyrolysis gas is subjected to preliminary plasma pyrolysis by non-thermal plasma generated by pulse-modulated dielectric barrier discharge in the primary plasma pyrolysis zone. (3) The gas after preliminary cracking is introduced into the plasma-catalytic coupling reaction zone for plasma-catalytic coupling reaction. Then the gas after reaction is cooled and separated to obtain hydrogen-rich gas and tar products. Some of the tar products are atomized and then subjected to plasma primary cracking and plasma-catalytic coupling reaction again to form a circulation path. The plasma-catalyst coupling reaction zone is equipped with an AAEMs-modified iron-based biochar catalyst; the AAEMs-modified iron-based biochar catalyst is distributed in the discharge gap between the electrodes in a discontinuous conductive structure; the plasma primary pyrolysis and the plasma-catalyst coupling reaction are carried out under CO2 gas conditions.

[0021] This invention mixes waste plastic containing low-density polyethylene (LDPE) with biomass raw materials and carries out a pyrolysis reaction under an inert atmosphere to generate primary pyrolysis gas; the primary pyrolysis gas contains tar components and combustible gases.

[0022] In this invention, the pyrolysis temperature can be 600~700℃, specifically 600℃, 650℃, or 700℃; the time can be 0.5h, 1h, 1.5h, or 2h. In this invention, the inert gas includes one or more of nitrogen, argon, or helium.

[0023] After obtaining the primary pyrolysis gas, the present invention performs preliminary plasma pyrolysis on the primary pyrolysis gas in the plasma primary pyrolysis zone to obtain the gas after preliminary pyrolysis; the plasma primary pyrolysis zone generates non-thermal plasma through pulse-modulated dielectric barrier discharge to perform preliminary plasma pyrolysis on the primary pyrolysis gas.

[0024] In this invention, non-thermal plasma generated by pulse-modulated dielectric barrier discharge can selectively break bonds in the tar and long-chain hydrocarbons in the primary pyrolysis gas, generating small-molecule intermediates. In this invention, the voltage of the pulse-modulated dielectric barrier discharge can be 5~30 kV, specifically 5 kV, 10 kV, 15 kV, 20 kV, or 25 kV; the frequency can be 1~50 kHz, specifically 10 kHz, 20 kHz, 30 kHz, 40 kHz, or 50 kHz; the duty cycle can be 10%~90%, specifically 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90%. Setting these parameters can regulate the electron energy distribution and improve the selective pyrolysis efficiency.

[0025] After obtaining the gas after preliminary cracking, the present invention introduces the gas after preliminary cracking into the plasma-catalytic coupling reaction zone to carry out the plasma-catalytic coupling reaction. Then, the gas after reaction is cooled and separated to obtain hydrogen-rich fuel gas and tar products. A portion of the tar products is atomized and then subjected to plasma primary cracking reaction and plasma-catalytic coupling reaction again to form a circulation path.

[0026] In this invention, the plasma-catalyst coupled reaction zone is equipped with an AAEMs-modified iron-based biochar catalyst. The AAEMs-modified iron-based biochar catalyst is distributed in a discontinuous conductive structure within the discharge gap (discharge region) between electrodes. This discontinuous conductive structure controls the spacing and conductive path between the AAEMs-modified iron-based biochar catalyst particles, ensuring that micro-discharge dominates within the discharge region. The local discharge channels are discretely distributed, avoiding the formation of continuous arc channels, thus creating a spatially overlapping coupling structure between the plasma active particle generation region and the catalytic reaction active sites within the same space. Furthermore, the AAEMs-modified iron-based biochar catalyst directly fills the discharge gap between electrodes, allowing the generation sites of the plasma active particles to spatially overlap with the surface active sites of the AAEMs-modified iron-based biochar catalyst, or enabling the plasma active particles to be distributed within a distance smaller than the discharge characteristic scale, thereby achieving deep cracking and reforming of tar and intermediate products.

[0027] In this invention, the iron-based biochar catalyst modified by AAEMs can be loaded onto a porous insulating support, so that the catalyst particles are spaced apart, thereby constructing a discontinuous conductive path.

[0028] In this invention, the iron loading in the AAEMs-modified iron-based biochar catalyst can be 5-15 wt%, specifically 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, or 15 wt%; the AAEMs are alkali metals / alkaline earth metals; specifically, they can be one or more of K, Na, Ca, and Mg, which can be used to enhance tar cracking and anti-carbon deposition performance.

[0029] In this invention, the loading of AAEMs in the AAEMs-modified iron-based biochar catalyst can be 1 to 10 wt%, specifically 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%.

[0030] In this invention, the preparation of the AAEMs-modified iron-based biochar catalyst includes the following steps: The biomass precursor was impregnated in a salt solution, and the resulting salt impregnated with biomass was pyrolyzed under a protective atmosphere to obtain the AAEMs-modified iron-based biochar catalyst.

[0031] In this invention, the salt solution includes iron salts and alkali metal / alkaline earth metal salts; the iron salts include ferric nitrate; the alkali metal / alkaline earth metal salts are nitrates of alkali metals or alkaline earth metals; in this invention, the impregnation can be an equal-volume impregnation; in this invention, the protective atmosphere can be a nitrogen atmosphere; the pyrolysis temperature can be 700°C and the time can be 1 hour.

[0032] In this invention, the plasma primary pyrolysis and plasma-catalytic coupling reaction are carried out under CO2 gas conditions; the volumetric flow rate of CO2 accounts for 5% to 50% of the total volumetric flow rate of the pyrolysis gas obtained from the pyrolysis reaction, and can be further 10% to 25%. This flow rate achieves a balance between suppressing tar formation and avoiding excessive dilution of combustible gas. In this invention, introducing CO2 gas into the plasma primary pyrolysis and plasma-catalytic coupling reaction allows it to generate active species under plasma action. These species are then converted into active oxygen species under plasma action and participate in the dry reforming reaction and the in-situ gasification of carbon on the catalyst surface. This forms a synergistic effect with the reforming reaction of the catalyst and promotes the conversion of organic components to CO and H2.

[0033] The gas obtained after the plasma-catalytic coupling reaction is cooled and separated to obtain hydrogen-rich fuel gas and tar products. Some of the tar products are then atomized and subjected to plasma primary cracking reaction and plasma-catalytic coupling reaction again to form a circulation path.

[0034] In this invention, the atomized tar products form droplets with an average particle size of less than 100 μm. The reintroduction of these droplets into the plasma reaction zone can improve the contact efficiency between the tar and the plasma active species.

[0035] In this invention, the tar products can be 20% to 80% of the total amount of separated tar, and can be further 30% to 60%; in order to form a tar recycling process and reduce system tar emissions.

[0036] In summary, through the regulation of discharge morphology by the discontinuous conductive catalyst structure, the spatial overlap and coupling of plasma and catalytic reaction, and the synergistic effect of CO2-involved active species generation and in-situ carbon deposition gasification, the tar recycling and conversion and the selectivity of H2 and CO in the gas are improved, while the deactivation of catalyst by carbon deposition is suppressed.

[0037] Figure 1 This invention provides a schematic diagram of the process flow for a multi-stage plasma-catalyst coupled biomass and plastic co-pyrolysis gas high-efficiency upgrading method. The diagram shows the core modules and material flow of the overall upgrading system, mainly including: a co-pyrolysis reactor, a plasma primary pyrolysis zone and a plasma-catalyst coupling zone (containing a discontinuous conductive catalyst) connected in sequence, a condensation separation system, and a tar circulation loop. The diagram clearly shows the input path of the primary pyrolysis gas and CO2, the output end of the hydrogen-rich gas after gas-liquid separation, and the closed-loop control process of the bottom tar flowing back to the plasma reactor through an atomizing nozzle for secondary pyrolysis.

[0038] In summary, this invention achieves efficient pyrolysis of tar and optimization of gas composition by constructing a multi-stage plasma-catalytic coupling reaction system and combining it with CO2 atmosphere control and tar reflux circulation, thereby increasing the gas calorific value and improving the system's operational stability.

[0039] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1 Low-density polyethylene (LDPE, purchased from Shanghai Yuanye Biotechnology Co., Ltd.) was dried at 60 ℃ for 12 hours. After drying, it was pulverized by a pulverizer (RT-200) to a particle size of 80 mesh. It was then mixed with corn stalks (CS, corn variety Zhengdan 958, which was naturally sun-dried for 14 days after sampling and then pulverized to 80 mesh) as raw materials. The LDPE and CS were mixed evenly at a mass ratio of 2:1 and fed into a fixed-bed pyrolysis reactor. The temperature was raised to 600 ℃ under a nitrogen atmosphere and the reaction was kept constant to obtain primary pyrolysis gas.

[0041] The primary pyrolysis gas is introduced into a multi-stage reaction system after being stabilized, including a plasma primary pyrolysis zone and a plasma-catalyst coupled reaction zone. The plasma reactor adopts a dielectric barrier discharge (DBD) structure, and the electrode space is filled with an AAEMs-modified iron-based biochar catalyst.

[0042] The catalyst is prepared as follows: using corn stalks as a precursor, it is impregnated in a mixed solution containing ferric nitrate and potassium nitrate by an equal-volume impregnation method, so that the Fe loading is 10 wt% and the K content is 5 wt%. After drying, it is pyrolyzed at 700℃ for 1 h under a nitrogen atmosphere to obtain the catalyst.

[0043] During the plasma reaction, a pulse-modulated power supply was used with a discharge voltage of 15 kV, a frequency of 10 kHz, and a duty cycle of 50%. Simultaneously, CO2 gas was introduced at the inlet of the primary plasma pyrolysis zone, with a volumetric flow rate of 20% of the pyrolysis gas flow rate.

[0044] After synergistic action of plasma and catalyst, the gas enters the condensation and separation system, where hydrogen-rich fuel gas (H2 and CO) and tar are separated. The obtained tar is heated to 100°C and then re-injected into the plasma reaction zone through an atomizing nozzle (average particle size of about 30 μm) for cyclic pyrolysis, with a tar reflux ratio of 50%.

[0045] Finally, the composition of the produced gas was analyzed, and the tar content and calorific value of the gas were determined.

[0046] Comparative Example 1: No Plasma Compared to Example 1, the DBD discharge system is not enabled, while all other conditions remain the same.

[0047] Comparative Example 2: No catalyst Compared to Example 1, no catalyst was filled in the plasma-catalytic reaction zone, while the other conditions remained the same.

[0048] Comparative Example 3: No CO2 conditions Compared to Example 1, CO2 gas was not introduced, but all other conditions remained the same.

[0049] Comparative Example 4: No Tar Recirculation Compared to Example 1, tar atomization reflux was not performed, while all other conditions remained the same.

[0050] Table 1. Effects of different systems on gas quality

[0051] Example 2: Synergistic Effect Verification Experiment The following experiments were conducted respectively: (1) Plasma treatment only: The operation steps are basically the same as in Example 1, except that the plasma-catalyst coupled reaction zone of the multi-stage reaction system is not filled with the AAEMs-modified iron-based biochar catalyst, but with an equal volume of quartz sand instead. The pulse modulation power supply is kept on (discharge voltage 15 kV, frequency 10 kHz, duty cycle 50%), so that the primary pyrolysis gas, CO2, and reflux tar are cracked only under the action of pure plasma discharge.

[0052] (2) Catalyst bed treatment only: The operation steps are basically the same as in Example 1, except that after filling the multi-stage reaction system with the AAEMs-modified iron-based biochar catalyst, the pulse-modulated dielectric barrier discharge power supply is turned off throughout the process (i.e., no discharge voltage is applied). This allows the primary pyrolysis gas, CO2, and reflux tar to undergo thermocatalytic cracking and reforming reactions only through a conventional catalyst bed.

[0053] (3) Simultaneous use of plasma and catalyst (Example 1).

[0054] Table 2. Validation of Synergistic Effect

[0055] Example 3: Experiment on the Influence of Catalyst Conductivity Structure Two types of fillers were set up for comparison: (1) continuous conductive filler (graphite); (2) insulating filler (quartz particles); the other conditions were the same as in Example 1.

[0056] Table 3 Influence of Discharge Structure

[0057] Example 4: Experiment on the effect of CO2 concentration CO2 gas was introduced at the inlet of the primary plasma pyrolysis zone, with a volumetric flow rate of 0%, 10%, 20% (i.e., Example 1), and 40% of the pyrolysis gas flow rate, and the other conditions were the same as in Example 1.

[0058] Table 4 Effect of CO2 concentration

[0059] Example 5: Tar Reflux Ratio Experiment The tar reflux ratio was adjusted to 0%, 30%, 50% (i.e., Example 1), and 100%, with the remaining conditions the same as in Example 1.

[0060] Table 5 Impact of Reflux Ratio

[0061] As shown in Tables 1-5, this invention achieves highly efficient tar cracking and significantly improved gas quality by constructing a discontinuous conductive catalyst structure that spatially overlaps with the plasma discharge region and introducing CO2 to participate in the reaction. In particular, the tar removal rate under the synergistic effect of plasma and catalyst is significantly higher than the simple sum of their individual effects, indicating a significant synergistic enhancement effect in the system of this invention. Furthermore, the introduction of CO2 not only participates in the dry reforming reaction but also effectively inhibits catalyst carbon deposition, improving system stability.

[0062] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A multi-stage plasma-catalysis coupled method for efficient upgrading of biomass pyrolysis gas, comprising the following steps: (1) Waste plastic containing low-density polyethylene is mixed with biomass raw materials and pyrolyzed under an inert atmosphere to generate primary pyrolysis gas; the primary pyrolysis gas contains tar components and combustible gas. (2) The primary pyrolysis gas is subjected to preliminary plasma pyrolysis in the primary plasma pyrolysis zone to obtain the gas after preliminary pyrolysis; The plasma preliminary pyrolysis zone generates non-thermal plasma through pulse-modulated dielectric barrier discharge to perform preliminary plasma pyrolysis on the primary pyrolysis gas. (3) The gas after preliminary cracking is introduced into the plasma-catalytic coupling reaction zone for plasma-catalytic coupling reaction. Then the gas after reaction is cooled and separated to obtain hydrogen-rich gas and tar products. Some of the tar products are atomized and then subjected to plasma primary cracking and plasma-catalytic coupling reaction again to form a circulation path. The plasma-catalyst coupling reaction zone is equipped with an AAEMs-modified iron-based biochar catalyst; the AAEMs-modified iron-based biochar catalyst is distributed in the discharge gap between the electrodes in a discontinuous conductive structure; the plasma primary pyrolysis and the plasma-catalyst coupling reaction are carried out under CO2 gas conditions.

2. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The voltage of the pulse-modulated dielectric barrier discharge is 5~30 kV, the frequency is 1~50 kHz, and the duty cycle is 10%~90%.

3. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The pyrolysis reaction is carried out at a temperature of 600-700℃ for a time of 0.5-2 hours.

4. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The AAEMs-modified iron-based biochar catalyst is supported on a porous insulating support, which creates a spaced distribution between the catalyst particles and constructs a discontinuous conductive path.

5. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The iron-based biochar catalyst modified with AAEMs has an iron loading of 5-15 wt%; the AAEMs are one or more of K, Na, Ca and Mg.

6. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The volumetric flow rate of CO2 accounts for 5% to 50% of the total volumetric flow rate of the pyrolysis gas obtained from the pyrolysis reaction.

7. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The tar products mentioned above account for 20% to 80% of the total separated tar.

8. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The tar products are atomized to form droplets with an average particle size of less than 100 μm.

9. The method for high-efficiency quality improvement of biomass pyrolysis gas as described in claim 1, characterized in that, The preparation of the AAEMs-modified iron-based biochar catalyst includes the following steps: The biomass precursor is impregnated in a salt solution, and the resulting salt impregnated with biomass is pyrolyzed under a protective atmosphere to obtain the AAEMs-modified iron-based biochar catalyst; the salt solution includes iron salts and alkali metal / alkaline earth metal salts.

10. A multi-stage plasma-catalysis coupled biomass pyrolysis gas high-efficiency upgrading system, characterized in that, It includes a co-pyrolysis reactor, a plasma reactor, a condenser system, a gas-liquid separator, and a tar collection tank connected in sequence; the tar collection tank and the plasma reactor are connected to form a loop; The plasma reactor includes a plasma primary pyrolysis zone and a plasma-catalytic coupling zone connected in sequence; the plasma-catalytic coupling zone is provided with an AAEMs-modified iron-based biochar catalyst; the AAEMs-modified iron-based biochar catalyst is distributed in the discharge gap between the electrodes in a discontinuous conductive structure.

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