Biomass pyrolysis catalyst and method thereof for biomass gasification

Abstract

The invention belongs to the technical field of biomass, and particularly relates to a biomass pyrolysis catalyst and a biomass gasification method thereof. The catalyst comprises 1, 4-butanediol tar and choline chloride complexed nickel chloride, wherein the content of the 1, 4-butanediol tar is 30 to 70 weight percent; the content of choline chloride complexed nickel chloride is 30-70 wt.%. The preparation method of the catalyst comprises the following steps: (A1) mixing choline chloride and nickel chloride, and reacting in inert gas to obtain a mixture; (A2) drying the mixture in vacuum to obtain choline chloride complexed nickel chloride; and (A3) mixing choline chloride complexed nickel chloride with 1, 4-butanediol tar to obtain the catalyst. The biomass gasification method comprises the following steps: (S1) pyrolyzing a biomass raw material by using the catalyst to obtain biochar; (S2) crushing biochar and pulping to obtain slurry; and (S3) gasifying the slurry to obtain the synthesis gas. The pyrolysis catalyst is simple to prepare, high in yield and high in pulping concentration, biomass can be efficiently converted into charcoal, and then synthesis gas is prepared.

Description

Technical Field

[0001] This invention belongs to the field of biomass resource utilization technology, specifically relating to a pyrolysis biomass catalyst and its method for biomass gasification. Background Technology

[0002] my country possesses abundant biomass resources, but traditional uses are limited to composting, animal feed, and combustion power generation, resulting in low utilization efficiency. Faced with the increasing demand for carbon trading, emission reduction policies, and green chemicals, the production of chemicals from biomass has become a research focus. Particularly in the field of biomass gasification, converting biomass into key feedstocks such as CO and H2, and then synthesizing green chemicals like methanol and formaldehyde, holds great promise. However, current technologies face challenges such as small scale, low conversion rates, and stringent raw material selection, necessitating technological innovation to enhance competitiveness and expand application scope.

[0003] Invention patent CN116103069A discloses a supported carbon fixation material for biomass pyrolysis. Using biomass as a carrier, a solvent dispersion and rotary evaporation method is employed to uniformly disperse a highly efficient carbon fixation agent, such as potassium carbonate or MCM41 molecular sieve, on the carrier surface to prepare the supported carbon fixation material. However, this pyrolysis catalyst has a long preparation process, requires a large amount of catalyst, and is complex to implement industrially. Summary of the Invention

[0004] The purpose of this invention is to solve the problems mentioned in the background art, such as the complex preparation of pyrolysis catalysts and the low efficiency of biomass pyrolysis, and to provide a biomass resource utilization technology that is simple to operate, has high catalytic efficiency, and is highly applicable.

[0005] To achieve the above objectives, a first aspect of the present invention provides a catalyst for biomass pyrolysis, said catalyst comprising 1,4-butanediol tar and choline chloride-complexed nickel chloride; wherein...

[0006] The content of the 1,4-butanediol tar is 30-70 wt.%.

[0007] The content of the choline chloride complexed nickel chloride is 30-70 wt.%.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, the method comprising the following steps:

[0009] (A1) Choline chloride and nickel chloride are mixed evenly and reacted under an inert gas protection to obtain a mixture;

[0010] (A2) The mixture was vacuum dried to obtain choline chloride complexed nickel chloride;

[0011] (A3) The catalyst is obtained by mixing the choline chloride complexed nickel chloride with 1,4-butanediol tar.

[0012] A third aspect of the present invention provides a biomass gasification method, the biomass gasification method comprising the following steps:

[0013] (S1) The pretreated biomass raw material is mixed with the above catalyst and then pyrolyzed in a pyrolysis reactor to obtain biochar.

[0014] (S2) The biochar is pulverized and pulped to obtain a slurry;

[0015] (S3) The slurry is subjected to a gasification reaction to obtain syngas.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] I. The catalyst of this invention is liquid at room temperature, enabling highly uniform mixing with biomass feedstock and greatly promoting the pyrolysis of biomass into biochar. Furthermore, this catalyst can promote the hydrodeoxygenation of biomass feedstock and suppress the generation of volatiles during pyrolysis, thus resulting in a high solids yield from the pyrolysis reaction.

[0018] Second, the catalyst preparation process of the present invention is simple. It only requires reacting choline chloride with nickel chloride under relatively mild conditions, and then mixing the resulting choline chloride-complexed nickel chloride with BDO tar.

[0019] Third, the catalyst of the present invention has a high solid yield and a high solid content in the slurry obtained in the subsequent pulping process when pyrolyzing biomass raw materials, so that the slurry has a high effective gas content in the downstream gasification reaction. Detailed Implementation

[0020] The present invention will be further described below through specific embodiments. The embodiments described in this invention are only for illustration and do not mean that the scope of the invention is limited to these embodiments.

[0021] The first aspect of this invention provides a catalyst for biomass pyrolysis, said catalyst comprising 1,4-butanediol (BDO) tar and choline chloride-complexed nickel chloride (CholineCl-NiCl2); wherein,

[0022] The content of the 1,4-butanediol tar is 30-70 wt.%.

[0023] The content of the choline chloride complexed nickel chloride is 30-70 wt.%.

[0024] In some embodiments, the 1,4-butanediol tar is derived from a by-product heavy component of a refining unit in a 1,4-butanediol production process in the art; preferably, the 1,4-butanediol tar is derived from a by-product heavy component of a refining unit in a process for producing 1,4-butanediol using the acetylene-aldehyde method. The refining unit is primarily used for deep purification of the crude product generated during the acetylene-aldehyde method for producing 1,4-butanediol, removing impurities such as unreacted raw materials, by-products, solvent residues, and high molecular weight polymers through distillation, extraction, crystallization, or other methods. During this process, some high molecular weight, non-volatile substances accumulate due to the inability to be effectively separated and are ultimately discharged as by-product heavy components; these by-product heavy components are what we refer to as 1,4-butanediol tar.

[0025] Furthermore, the 1,4-butanediol tar comprises 6-15 parts of sodium formate, 15-25 parts of 1,4-butanediol, and 20-40 parts of 1,4-butanediol-derived polymer (all by weight), and may also contain additional water.

[0026] Furthermore, the 1,4-butanediol-derived polymer is selected from at least one of cycloacetal, hemiacetal, and 2-(4-hydroxybutoxy)tetrahydrofuran.

[0027] The inventors have discovered that sodium formate in BDO tar promotes the biomass pyrolysis process, as summarized below:

[0028] I. Formic acid functional groups are hydrogen donors that promote depolymerization, thus promoting the hydrodeoxygenation reaction of biomass feedstock and increasing biochar yield.

[0029] Second, sodium functional groups can inhibit the generation of volatiles during pyrolysis and improve biochar yield;

[0030] Third, in the catalyst of the present invention, the formic acid functional group and the sodium functional group also have a synergistic effect on the pyrolysis behavior of lignin, which can catalytically break the bonds of cellulose and other substances at high temperature to obtain biochar. At the same time, some oxygen-containing groups such as hydroxyl and carboxyl groups are converted into water and CO2, which increases the solid content of the pulp in the subsequent pulping process, and finally has a high effective gas ratio in the syngas products of the gasification reaction.

[0031] In this invention, the catalyst is liquid at room temperature, which is significantly different from traditional solid metal salt catalysts that cannot be uniformly dispersed.

[0032] This invention ingeniously utilizes the mixing properties of BDO tar and the CholineCl-NiCl2 metal complex, enabling highly uniform mixing of the catalyst and biomass feedstock in an atomized form at room temperature. This improves mass transfer and reaction efficiency, significantly promoting the efficient conversion of biomass pyrolysis into biochar. Simultaneously, transition metal and alkali metal catalysts such as Ni and Na reduce the activation energy of the biomass pyrolysis reaction. The synergistic effect of these two catalysts significantly reduces the formation of volatile organic compounds, further enhancing pyrolysis efficiency and biochar yield.

[0033] In this invention, the active component of the catalyst is CholineCl-NiCl2, which is a metal complex type ionic liquid. Its high solubility and polarity promote thorough mixing with BDO tar and biomass feedstock, achieving a uniform distribution of the active component.

[0034] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, the method comprising the following steps:

[0035] (A1) Choline chloride and nickel chloride are mixed evenly and reacted under an inert gas protection to obtain a mixture;

[0036] (A2) The mixture was vacuum dried to obtain choline chloride complexed nickel chloride;

[0037] (A3) The catalyst is obtained by mixing the choline chloride complexed nickel chloride with 1,4-butanediol tar.

[0038] In some embodiments, in step (A1), choline chloride and nickel chloride are mixed in equimolar amounts, and the reaction is carried out under an inert gas atmosphere with continuous stirring.

[0039] Furthermore, the reaction temperature is 60-150℃, preferably 80-110℃; the reaction time is 1-5h, preferably 2-4h.

[0040] In some embodiments, in step (A2), the temperature of the vacuum drying is 60-150°C, preferably 80-110°C; and the time of the vacuum drying is 5-10 hours, preferably 2-4 hours.

[0041] A third aspect of the present invention provides a biomass gasification method, the biomass gasification method comprising the following steps:

[0042] (S1) The pretreated biomass raw material is mixed with the above catalyst and then pyrolyzed in a pyrolysis reactor to obtain biochar.

[0043] (S2) The biochar is pulverized and pulped to obtain a slurry;

[0044] (S3) The slurry is subjected to a gasification reaction to obtain syngas.

[0045] In some embodiments, in step (S1), the biomass raw material may undergo pretreatment such as sorting, drying, crushing and sieving before pyrolysis.

[0046] Furthermore, the biomass raw material is selected from at least one of distiller's grains, straw, and leaves.

[0047] Furthermore, the moisture content of the biomass raw material is 1-20 wt.%, preferably 1-10 wt.%.

[0048] Furthermore, the particle size of the biomass raw material is 5-50 mm, preferably 10-40 mm.

[0049] In step (S1), under the catalytic action of a pyrolysis catalyst, cellulose in biomass undergoes a pyrolysis reaction, simultaneously converting its oxygen-containing groups, such as hydroxyl and carboxyl groups, into water and carbon dioxide. Preferably, the pyrolysis is carried out in an inert gas atmosphere, such as a nitrogen atmosphere.

[0050] In some embodiments, the pyrolysis temperature is 200-400°C, preferably 250-350°C.

[0051] Furthermore, the pyrolysis time is 0.5-3 hours, preferably 1-2 hours.

[0052] Furthermore, the pyrolysis reactor is one or more of a fixed-bed, fluidized-bed, or rotary kiln reactor.

[0053] Furthermore, the amount of catalyst added is 0.5-5 wt.%, preferably 1-3 wt.% (based on the amount of biomass feedstock).

[0054] In some embodiments, the gas phase generated by pyrolysis is sent to water washing and alkali washing towers for treatment after being cyclone-splittered or gas-liquid separated, and discharged after passing the treatment; the tar generated by pyrolysis is mixed with the slurry generated in step (S2) and sent together to the gasification unit for gasification.

[0055] In some embodiments, the solid yield of the pyrolysis reaction is 65-80%.

[0056] Those skilled in the art will understand that the solids yield refers to the proportion of the remaining solids to the total amount of biomass feedstock (excluding moisture) after the pyrolysis reaction. Given that the core objective of the pyrolysis process is to effectively remove oxygen from the biomass feedstock so that a higher concentration slurry can be obtained through the pulverization process in the subsequent step (S2), thereby reducing carbon dioxide generation in the gasification reaction in step (S3), the pyrolysis step aims to maximize the solids yield while removing oxygen as thoroughly as possible.

[0057] In step (S2), the biochar obtained from pyrolysis is pulverized and pulped (using water as a dispersion solvent). This process yields a slurry with a high solids content and uniform particle size distribution. This slurry is characterized by its ability to significantly increase the content of effective gas in the syngas during the gasification reaction, and its high solids content (i.e., low water content) effectively reduces the energy consumption required for the gasification process.

[0058] In some embodiments, in step (S2), the pulverizing and pulping process uses at least one of a homogenizing pump, a ball mill, and a rod mill, preferably a homogenizing pump and / or a rod mill.

[0059] Furthermore, the pulverization and pulping process concentrates the particle size of the pulp in the range of 10-100 μm, and D 50 =30-50μm, D 90 =80-100μm.

[0060] Furthermore, the solid content of the slurry is 40-60 wt.%.

[0061] In step (S2), during the pulverizing and pulping process, pulping aids may be added to improve the stability and fluidity of the pulp.

[0062] In some embodiments, in step (S2), the pulping aid is at least one of naphthalene sulfonate polymer, sodium polystyrene sulfonate, or lignin sulfonate;

[0063] Furthermore, the amount of the pulping aid added is 0.2-0.8 wt.% (based on the amount of pulp used).

[0064] In step (S3), the slurry is pumped to the downstream gasification unit by a high-viscosity material conveying pump.

[0065] As is known to those skilled in the art, during the pulverization and pulping process of biochar, in order to increase the solid content of the slurry, the amount of solvent (e.g., water) added should be as small as possible. However, the higher the solid content, the higher the viscosity. Currently, the maximum viscosity range of the slurry that can be transported is 100-3000 cp. Therefore, it is necessary to ensure that the viscosity of the slurry does not exceed the maximum viscosity allowed by the high-viscosity material conveying pump.

[0066] In some embodiments, in step (S3), the reaction pressure of the gasification reaction is 0.9-1.2 MPa, the reaction temperature is 1000-1300°C, and the residence time is 3-7 s.

[0067] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the preparation method of this invention will be described in detail below through specific embodiments and comparative examples.

[0068] In the following embodiments and comparative examples,

[0069] The biomass 1 is distiller's grains 1, which has a moisture content of 15 wt.% and a particle size of 15-25 mm;

[0070] The biomass 2 is wheat straw, with a moisture content of 15 wt.% and a particle size of 15-25 mm;

[0071] The biomass 3 is tree leaves with a water content of 15 wt.% and a particle size of 15-25 mm;

[0072] The biomass 4 is distiller's grains 2, which has a moisture content of 1 wt.% and a particle size of 40-50 mm;

[0073] The biomass 5 is distillers' grains 3, with a moisture content of 20 wt.% and a particle size of 5-15 mm.

[0074] The preparation method of the pyrolysis catalyst is as follows:

[0075] Choline chloride and nickel chloride were mixed in equimolar amounts and heated and stirred under nitrogen protection at 100°C for 4 hours. The resulting viscous liquid was then dried under vacuum at 90°C for 10 hours to obtain choline chloride-complexed nickel chloride. The choline chloride-complexed nickel chloride was then mixed with 1,4-butanediol tar at weight ratios of 70:30, 50:50, and 30:70, respectively, to obtain pyrolysis catalyst 1 (C1), pyrolysis catalyst 2 (C2), and pyrolysis catalyst 3 (C3).

[0076] The 1,4-butanediol tar is a by-product heavy component of the refining unit of the acetylacetyl aldehyde process for producing 1,4-butanediol at Wanhua Chemical Company, containing 10% sodium formate, 40% water, 20% BDO, and 30% BDO-derived polymers.

[0077] Example 1 (A1)

[0078] (S1) The pyrolysis catalyst is evenly sprayed onto the biomass raw material, and then conveyed by a screw conveyor to a rotary kiln pyrolysis reactor for catalytic pyrolysis to obtain biochar; wherein,

[0079] The biomass raw material is biomass 1;

[0080] The pyrolysis catalyst is C1, and the addition amount is 2.0 wt.%.

[0081] The pyrolysis reaction was carried out at a temperature of 350°C for 1.5 hours.

[0082] The solid yield of the pyrolysis reaction was 77%.

[0083] (S2) A pulping aid is added to the biochar, and then the mixture is pulverized and pulped using a rod mill to obtain a pulp; wherein,

[0084] The pulping aid is a naphthalene sulfonate polymer, added at a rate of 0.5 wt.%.

[0085] The slurry has a solid content of 53 wt.%, and the particle size of the biochar in the slurry is: D 50 =40μm, D 90 =90μm.

[0086] (S3) The slurry is pumped to a gasifier via a high-viscosity material conveying pump for gasification reaction to obtain syngas; wherein...

[0087] The gasification reaction has a reaction pressure of 1.1 MPa, a reaction temperature of 120°C, and a residence time of 4 s.

[0088] The volume composition of the synthesis gas is: CO 36.5%, H2 30.9%, CO2 30.7%, and N2 1.9%.

[0089] Example 2 (A2)

[0090] The procedure is the same as in Example 1, except that:

[0091] In step (S1),

[0092] The biomass raw material is biomass 2;

[0093] The solid yield of the pyrolysis reaction was 73%.

[0094] In step (S2),

[0095] The slurry has a solid content of 42 wt.%.

[0096] In step (S3),

[0097] The volume composition of the synthesis gas is: CO 27.2%, H2 32.2%, CO2 39.8% and N2 0.8%.

[0098] Example 3 (A3)

[0099] The procedure is the same as in Example 1, except that:

[0100] In step (S1),

[0101] The biomass raw material is biomass 3;

[0102] The solid yield of the pyrolysis reaction was 68%.

[0103] In step (S2),

[0104] The slurry has a solid content of 46 wt.%.

[0105] In step (S3),

[0106] The volume composition of the synthesis gas is: CO 30.4%, H2 31.6%, CO2 36.3%, and N2 1.7%.

[0107] Example 4 (A4)

[0108] The procedure is the same as in Example 1, except that:

[0109] In step (S1),

[0110] The biomass raw material is biomass 4.

[0111] In step (S3), the volume composition of the synthesis gas is: CO 36.5%, H2 30.9%, CO2 30.7% and N2 1.9%.

[0112] Example 5 (A5)

[0113] The procedure is the same as in Example 1, except that:

[0114] In step (S1),

[0115] The biomass raw material is biomass 5.

[0116] In step (S3), the volume composition of the synthesis gas is: CO 36.5%, H2 30.9%, CO2 30.7% and N2 1.9%.

[0117] Example 6 (A6)

[0118] The procedure is the same as in Example 1, except that:

[0119] In step (S1),

[0120] The pyrolysis catalyst is C2, and the amount added remains unchanged;

[0121] The solid yield of the pyrolysis reaction was 78%.

[0122] In step (S2),

[0123] The slurry has a solid content of 54 wt.%.

[0124] In step (S3), the volume composition of the synthesis gas is: CO 37.4%, H2 31.2%, CO2 29.5% and N2 1.9%.

[0125] Example 7 (A7)

[0126] The procedure is the same as in Example 1, except that:

[0127] In step (S1),

[0128] The pyrolysis catalyst is C3, and the amount added remains unchanged;

[0129] The solid yield of the pyrolysis reaction was 79%.

[0130] In step (S2),

[0131] The slurry has a solid content of 56 wt.%.

[0132] In step (S3), the volume composition of the synthesis gas is: CO 39.8%, H2 31.7%, CO2 26.6%, and N2 1.9%.

[0133] Example 8 (A8)

[0134] The procedure is the same as in Example 1, except that:

[0135] In step (S1),

[0136] The amount of the pyrolysis catalyst C1 added is 5.0 wt.%.

[0137] The pyrolysis reaction was carried out at a temperature of 200°C for 3 hours.

[0138] The solid yield of the pyrolysis reaction was 79%.

[0139] In step (S2),

[0140] The amount of the pulping aid added is 0.8 wt.%.

[0141] The slurry has a solid content of 52 wt.%.

[0142] In step (S3), the volume composition of the synthesis gas is: CO 36.1%, H2 30.5%, CO2 31.5%, and N2 1.9%.

[0143] Example 9 (A9)

[0144] The procedure is the same as in Example 1, except that:

[0145] In step (S1),

[0146] The amount of the pyrolysis catalyst C1 added is 0.5 wt.%.

[0147] The pyrolysis reaction was carried out at a temperature of 400℃ for 0.5 hours.

[0148] The solid yield of the pyrolysis reaction is 75%.

[0149] In step (S2),

[0150] The amount of the pulping aid added is 0.2 wt.%.

[0151] The slurry has a solid content of 51 wt.%.

[0152] In step (S3), the volume composition of the synthesis gas is: CO 35.4%, H2 30.7%, CO2 32.0%, and N2 1.9%.

[0153] Comparative Example 1 (D1)

[0154] The procedure is the same as in Example 1, except that:

[0155] In step (S1),

[0156] Without adding a pyrolysis catalyst, biomass raw material 1 is directly subjected to pyrolysis reaction;

[0157] The solid yield of the pyrolysis reaction was 52%.

[0158] In step (S2),

[0159] The slurry has a solid content of 42 wt.%.

[0160] In step (S3),

[0161] The volume composition of the synthesis gas is: CO 28.4%, H2 31.1%, CO2 38.7%, and N2 1.8%.

[0162] Comparative Example 2 (D2)

[0163] The procedure is the same as in Example 1, except that:

[0164] In step (S1),

[0165] The pyrolysis catalyst is BDO tar, and the amount added remains unchanged.

[0166] The solid yield of the pyrolysis reaction was 62%.

[0167] In step (S2),

[0168] The slurry has a solid content of 46 wt.%.

[0169] In step (S3),

[0170] The volume composition of the synthesis gas is: CO 31.3%, H2 32.0%, CO2 34.9% and N2 1.8%.

[0171] Comparative Example 3 (D3)

[0172] The procedure is the same as in Example 1, except that:

[0173] In step (S1),

[0174] The pyrolysis catalyst is choline chloride complexed with nickel chloride, and the amount added remains unchanged.

[0175] The solid yield of the pyrolysis reaction is 60%.

[0176] In step (S2),

[0177] The slurry has a solid content of 48 wt.%.

[0178] In step (S3),

[0179] The volume composition of the synthesis gas is: CO 33.7%, H2 31.3%, CO2 33.1%, and N2 1.9%.

[0180] Note: In this field, solids yield is a conventional indicator for evaluating the efficiency of biomass pyrolysis. A higher solids yield indicates lower carbon loss in the biomass feedstock, meaning less loss of biomass feedstock and higher efficiency of the pyrolysis process.

[0181] As can be seen from Example 1 and Comparative Examples 1-3, the biomass pyrolysis reaction with the catalyst of the present invention has a high solid yield. Therefore, the pyrolysis catalyst of the present invention can significantly promote the pyrolysis of biomass raw materials and reduce the raw material loss during the pyrolysis process.

[0182] As can be seen from Examples 1-3, the performance of different types of biomass raw materials (distillers' grains, wheat straw, and leaves) in the pyrolysis reaction significantly affects the solid yield, specifically: distillers' grains > wheat straw > leaves.

[0183] As can be seen from Examples 1, 4, and 5, for the same type of biomass raw material (distillers' grains), within a certain range, its moisture content and particle size have little effect on the pyrolysis reaction.

[0184] As can be seen from Examples 1, 6, and 7, for the pyrolysis catalyst of the present invention, appropriately increasing the content of 1,4-butanediol tar can improve the solid yield of the pyrolysis reaction.

Claims

1. A catalyst for biomass pyrolysis, characterized in that, The catalyst comprises 1,4-butanediol tar and choline chloride complexed with nickel chloride; wherein... The content of the 1,4-butanediol tar is 30-70 wt.%. The content of the choline chloride complexed nickel chloride is 30-70 wt.%.

2. The catalyst according to claim 1, characterized in that, The 1,4-butanediol tar is a by-product heavy component from the refining unit of 1,4-butanediol production. Preferably, the 1,4-butanediol tar comprises 6-15 parts sodium formate, 15-25 parts 1,4-butanediol, and 20-40 parts a derivative polymer of 1,4-butanediol. The 1,4-butanediol derivative polymer is at least one of cycloacetal, hemiacetal, and 2-(4-hydroxybutoxy)tetrahydrofuran.

3. A method for preparing the catalyst according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (A1) Choline chloride and nickel chloride are mixed evenly and reacted under an inert gas protection to obtain a mixture; (A2) The mixture was vacuum dried to obtain choline chloride complexed nickel chloride; (A3) The catalyst is obtained by mixing the choline chloride complexed nickel chloride with 1,4-butanediol tar.

4. The preparation method according to claim 3, characterized in that, In step (A1), choline chloride and nickel chloride are mixed in equimolar amounts; In step (A1), the reaction temperature is 60-150℃, preferably 80-110℃; the reaction time is 1-5h, preferably 2-4h. In step (A2), the vacuum drying temperature is 60-150℃, preferably 80-110℃; the vacuum drying time is 5-10h, preferably 2-4h.

5. A biomass gasification method, characterized in that, The biomass gasification method includes the following steps: (S1) The pretreated biomass raw material is mixed with the catalyst according to claim 1 or 2 or the catalyst prepared by the preparation method according to claim 3 or 4 and then pyrolyzed in a pyrolysis reactor to obtain biochar; (S2) The biochar is pulverized and pulped to obtain a slurry; (S3) The slurry is subjected to a gasification reaction to obtain syngas.

6. The biomass gasification method according to claim 5, characterized in that, In step (S1), the biomass raw material is selected from one or more of distiller's grains, straw, and leaves; The pyrolysis reactor is a fixed-bed pyrolysis reactor, a fluidized-bed pyrolysis reactor, or a rotary kiln pyrolysis reactor.

7. The biomass gasification method according to claim 5 or 6, characterized in that, In step (S1), the pyrolysis temperature is 200-400℃, preferably 250-350℃; The pyrolysis time is 0.5-3 hours, preferably 1-2 hours; The pyrolysis is carried out in a nitrogen atmosphere; Based on the amount of the biomass feedstock used, the amount of catalyst added is 0.5-5 wt.%, preferably 1-3 wt.%.

8. The biomass gasification method according to any one of claims 5 to 7, characterized in that, In step (S2), the pulverization and pulping process uses at least one of a homogenizing pump, a ball mill, and a rod mill; The particle size D of the biochar in the slurry 50 =30-50μm, D 90 =80-100μm.

9. The biomass gasification method according to any one of claims 5 to 8, characterized in that, In step (S2), during the pulverization and pulping process, a pulping aid is added to the biochar; the amount of the pulping aid added is 0.2-0.8 wt.% based on the pulp. Preferably, the pulping aid is at least one of naphthalene sulfonate polymer, sodium polystyrene sulfonate, or lignin sulfonate.

10. The biomass gasification method according to any one of claims 5 to 9, characterized in that, In step (S3), the reaction pressure of the gasification is 0.9-1.2 MPa, the reaction temperature is 1000-1300℃, and the residence time is 3-7 s.