A method for preparing biomass carbon materials using a two-stage carbonization kiln process

Abstract

This invention discloses a method for preparing biomass carbon materials using a two-stage carbonization kiln process. The method involves cutting, crushing, and removing impurities from the biomass material, then loading it into the first rotating drum of the carbonization kiln. The first rotating drum is heated from room temperature to 50°C–150°C and held at this temperature for 0.5–2 hours. Water vapor is then introduced, along with a catalyst solution, which is thoroughly mixed with the biomass fragments and conveyed to the second rotating drum via a conveyor. A protective gas (N2) is introduced, and the pressure is adjusted to 1–2 MPa. The second rotating drum is then heated to 150°C–800°C. A leaching solution is then sprayed in, and the mixture is held at this temperature for 2–4 hours. After cooling to room temperature, the final product, biomass carbon material, is obtained. This invention combines the advantages of hydrothermal and pyrolysis technologies, achieving a resource utilization process that turns waste into treasure through two-stage temperature control and leaching solutions. This invention can achieve targeted catalytic carbonization of target products according to specific needs, and has significant industrial application value.

Description

Technical Field

[0001] This invention relates to a method for preparing biomass carbon materials, and more particularly to a method for preparing biomass carbon materials using a two-stage carbonization kiln process. This method is mainly used for the preparation of electrode carbon materials, carbon black, catalysts and their supports, and belongs to the technical fields of high-value utilization of waste biomass resources and preparation of biomass carbon materials. Background Technology

[0002] Biomass, as a zero-carbon emission and sustainable resource (a potential fossil fuel alternative and one of the few viable renewable energy resources), boasts diverse types, high yields, and low or no cost. However, its utilization is very limited due to factors such as rural economic development levels, energy infrastructure conditions, and residents' affordability. The main challenges in utilizing waste biomass are: first, fibrous biomass is a mixture, making it difficult to separate any single component; second, most biomass is poorly soluble, hindering the implementation of many solution-based methods for controlling material morphology, pore structure, or surface properties. The rational and efficient utilization of biomass has become an important research topic.

[0003] Carbon materials, due to their controllable specific surface area, porous structure, excellent thermal stability, and electrical / thermal conductivity, are widely used in catalysis, energy storage, batteries, and environmental applications. Furthermore, with the rapid development of energy storage and energy conversion technologies, the application of nano-carbon materials in electrochemistry is becoming increasingly widespread, ushering in a new era for carbon materials in the "new energy field." Currently, there are many strategies for preparing carbon materials, but the direct carbonization process from biomass mainly relies on pyrolysis and hydrothermal methods. Pyrolysis carbonization involves directly pyrolyzing raw materials at high temperatures in a fixed bed to prepare carbon materials. It has advantages such as simple process, short flow, large production scale, and low cost; however, its high reaction temperature makes the reaction process relatively difficult to control, resulting in inconsistent quality between different batches of carbon materials. Hydrothermal carbonization is a very attractive biomass treatment method because it can easily process wet biomass and waste under low temperature and its own pressure, enriching and converting organic carbon into coal-like solid fuels. The energy density of the solid products is improved, and the macromolecular structure of the original biomass is modified, producing porous carbonized products that are easier to convert into heat, power, or fuel than the original materials. However, carbon materials prepared by traditional hydrothermal methods typically have a very low specific surface area, resulting in low strength and easy deformation as structural products, making them difficult to use in catalysis. Furthermore, traditional hydrothermal carbonization processes generate a significant amount of liquid byproducts, whose high-value components are not fully utilized; and the treatment of these liquid byproducts is difficult, increasing the production cost of carbonizing waste biomass. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for preparing high-end carbon materials using agricultural and forestry waste (straw, rice straw, fruit shells, corn cobs, etc.), kitchen waste (steamed buns, bread, rice, vegetables, etc.), livestock and poultry manure, and organic sludge (with a carbon content of more than 30%) as raw materials.

[0005] This invention relates to a two-stage carbonization kiln process for preparing biomass carbon materials. The biomass material is cut, crushed, and impurity-removed before being loaded into the first rotating drum of the carbonization kiln. The first rotating drum is heated from room temperature to 50°C–150°C and held at this temperature for 0.5–2 hours to allow moisture to better enter the pores. Moisture is then introduced, along with a catalyst solution, which is thoroughly mixed with the biomass fragments and conveyed to the second rotating drum via a conveyor. A protective gas (N2) is introduced, and the pressure is adjusted to 1–2 MPa. The second rotating drum is then heated from room temperature to 150°C–800°C at a rate of 5–20°C / min. A washing liquid is then sprayed into the second rotating drum using a liquid pump and held at this temperature for 2–4 hours. After cooling to room temperature, the final product, biomass carbon material, is obtained.

[0006] Biomass materials include agricultural and forestry waste, organic kitchen waste, and organic sludge. Agricultural and forestry waste includes straw, rice straw, fruit shells, and corn cobs; organic kitchen waste includes steamed buns, bread, rice, and vegetables; and organic sludge includes fecal sludge.

[0007] The introduction of water vapor promotes the hydrolysis of biomass materials and a series of reactions. When the biomass material itself has a high moisture content, the moisture content can be reduced through a first-stage temperature control program. If the biomass itself has a low moisture content, the water vapor content can be increased through water vapor regulation, thereby precisely controlling the carbonization process and process water consumption. The carbonization process can be achieved when the water vapor content is 5%–30% of the dry biomass, but the optimal range for the carbonization water vapor medium is 5%–15%. The liquid produced during the carbonization process can be recovered and reused.

[0008] The catalyst is at least one of the chloride, sulfate, and nitrate salts corresponding to iron, cobalt, copper, and nickel; the concentration of the catalyst solution is 5-30%; the amount of catalyst solution introduced is 1%-10% of the dry mass fraction of the waste biomass. The infiltration of iron, cobalt, copper, and nickel elements into the catalyst is beneficial for the generation of carbon materials containing multiple metals, and the introduction of iron and copper into the electrode further enhances the performance.

[0009] The leaching solution is a mixed solution of two or more carbonates, or a mixed solution of carbonates and ionic liquids, with a mass concentration of 30-60%. The carbonates are sodium carbonate, potassium carbonate, zinc carbonate, cobalt carbonate, and iron carbonate; the ionic liquid is at least one of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, and 1-butyl-3-methylimidazolium dicyandiamide. The amount of leaching solution added is 5%-30% of the dry mass fraction of the waste biomass. Under set pressure and temperature conditions, the supplementary action of the carbonate series leaching solution prepared with alkaline sodium carbonate and potassium carbonate provides a transport channel for sodium and potassium ions to enter the carbon material. The decomposition of carbonate ions also promotes the transport of chemical substances to a certain extent, increases the diffusion rate, and can promote the embedding or growth of metal ions or functional groups such as potassium and sodium on the carbon material. Adding ionic liquids to the eluent can promote low intercalation potentials, the highest possible energy density per unit weight, and higher electron transport properties, resulting in more advanced electrode and catalytic carbon materials. Therefore, the presence of the eluent can increase electron and ion transport channels, improve the conductivity of the synthesized materials, and enhance the carbonization and activation effects of the carbon materials.

[0010] Biomass materials are produced continuously in a carbonization kiln with two rotary drums. After the second stage, the carbon content in the biomass carbon material is between 45% and 90%, and the oxygen content is between 5% and 20%. The liquid generated during carbonization can be recovered and reused.

[0011] This invention utilizes steam, catalyst, rinsing liquid, and a two-stage temperature-controlled (low-temperature) treatment process in a carbonization kiln to promote the dehydrogenation and deoxygenation of lignocellulosic biomass. Under the action of steam (which can be supercritical) and nitrate or sulfate catalysts, oxygen atoms in the biomass are rapidly removed. The formation of various organic acids, such as acetic acid, formic acid, and lactic acid, as byproducts typically leads to a decrease in pH. These acids further promote hydrolysis, yielding smaller fragments from oligomers and monomers. With increasing reaction intensity, the number of colloidal carbon particles increases significantly. After the two-stage treatment, the biochar has a higher carbon ratio and lower oxygen content. This method avoids the problems of difficult residual liquid treatment and new pollutants after carbonization, achieved through intermittent hydrothermal reactors. The generated liquid is not discharged externally, effectively utilizing its own characteristics and maximizing the utilization of waste resources. This multi-pronged process lays the foundation for subsequent use as a support (electrode system or catalyst system), fully exposed to the reaction medium to participate in the reaction, improving efficiency and increasing cycle stability. It can be applied to electrode carbon materials, carbon black, catalysts, and catalyst supports.

[0012] In summary, the present invention has the following advantages over the prior art:

[0013] 1. This invention employs a two-stage carbonization kiln process, utilizing the advantages of low-temperature carbonization, steam activation, and high carbon yield in hydrothermal methods, coupled with the continuous mode of pyrolysis processes, overcoming the shortcomings of existing intermittent hydrothermal reactor processes such as complex operation, numerous new pollutants, low yield, high energy consumption, and limited carbon varieties in traditional pyrolysis methods. It achieves directional carbonization of biomass, further expanding the application market for biomass carbon and possessing significant industrial application value.

[0014] 2. The carbon materials prepared by this invention have abundant micro- and nano-structures and excellent electrochemical performance, providing a foundation for the development of high-end carbon materials (electrode system and catalytic system).

[0015] 3. The carbon materials prepared by this invention have a wide range of biomass sources, are low in cost, and are green and sustainable. Detailed Implementation

[0016] The preparation method and application performance of the biochar of the present invention will be further explained below through specific embodiments.

[0017] Example 1

[0018] Preparation of carbon materials: 1000g of waste corn stalks were weighed, chopped, crushed, and impurities removed. They were then loaded into the first rotary drum of a carbonization kiln. The first rotary drum was heated from room temperature to 100℃ and held for 1 hour. 100g of water vapor was introduced and thoroughly mixed with the biomass fragments. The mixture was then conveyed to the second rotary drum, where the pressure was adjusted to 1MPa, and the temperature was raised to 200℃ at a rate of 5℃ / min, then held for 2 hours. After cooling to room temperature, the final product was obtained.

[0019] Carbon material performance testing: Carbon material was used as both an electrode and a conductive agent, coated onto copper foil, vacuum dried, and cut to obtain electrode sheets. Using metallic sodium as the counter electrode, 1M NaPF6 EC DMC (1:1) electrolyte, and glass fiber as the separator, a battery was assembled. The Xinwei battery testing system was used, with the following test conditions: charge / discharge current 30mA / g, voltage range 0.01~2.5V vs Na / Na + Test results: Specific capacity 120mAh / g, initial charge / discharge efficiency 55%; after 100 cycles, 47% capacity retention remains.

[0020] Example 2

[0021] Preparation of carbon materials: 1000g of waste corn stalks were weighed, chopped, crushed, and impurities removed. They were then loaded into the first rotating drum of a carbonization kiln. The first rotating drum was heated from room temperature to 80℃ and held for 1 hour. 150g of water vapor was introduced, and simultaneously, 10mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) was injected as a catalyst. After thorough mixing with the biomass fragments, the mixture was conveyed into the second rotating drum. A protective gas (N2) was introduced, and the pressure was adjusted to 2MPa. The temperature was raised to 200℃ at a rate of 5℃ / min. Then, 300mL of eluent was sprayed into the second rotating drum of the carbonization kiln using a liquid pump, and the temperature was held for 2 hours. After cooling to room temperature, the final product was obtained. The rinsing solution is a 1:1 volume ratio of 50% sodium carbonate solution and 30% potassium carbonate solution, with the addition of 1% (mass fraction in the mixed solution) of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide salt.

[0022] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 300mAh / g, initial charge / discharge efficiency 92%; after 100 cycles, the capacity retention rate is still 87%.

[0023] Example 3

[0024] Preparation of carbon materials: 1000g of waste corn stalks were weighed, chopped, crushed, and impurities removed. They were then loaded into the first rotating drum of a carbonization kiln. The first rotating drum was heated from room temperature to 100℃ and held for 1 hour. 200g of water vapor was introduced, along with 10mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) as a catalyst, which was thoroughly mixed with the biomass fragments. The mixture was then conveyed to the second rotating drum, where a protective gas (N2) was introduced and the pressure was adjusted to 2MPa. The temperature was then increased to 180℃ at a rate of 5℃ / min. 300mL of leaching liquid was then injected into the second rotating drum using a liquid pump, and the pressure was kept constant at 2MPa. 100g of water vapor was added, and the temperature was maintained at 180℃ for 4 hours. After cooling to room temperature, the final product was obtained. The leaching solution was a 1:1 volume mixture of 60% sodium carbonate solution and 40% potassium carbonate solution, with the addition of 1% 1-butyl-3-methylimidazolium trifluoromethane sulfonate. Characterization showed that the oxygen atomic content in the waste biomass material exiting the second drum was 8%.

[0025] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 200mAh / g, initial charge / discharge efficiency 86%; after 100 cycles, the capacity retention rate is still 83%.

[0026] Example 4

[0027] Preparation of carbon materials: 1000g of waste rice straw was weighed, chopped, crushed, and impurities removed. It was then loaded into the first rotating drum of a carbonization kiln. The first rotating drum was heated from room temperature to 60℃ and held for 2 hours. 200g of water vapor was introduced, along with 15mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) as a catalyst. After thorough mixing with the biomass fragments, the mixture was conveyed to the second rotating drum. A protective gas (N2) was introduced, and the pressure was adjusted to 2MPa. The temperature was raised to 220℃ at a rate of 5℃ / min and maintained for 3 hours. After further heating to 220℃, 300mL of eluent was injected into the second rotating drum of the carbonization kiln via a liquid pump, and the temperature was maintained at 220℃ for 2 hours. After cooling to room temperature, the final product was obtained. The eluent was a mixture of 50% sodium carbonate solution and 40% potassium carbonate solution in a 2:1 volume ratio, with 1% 1-butyl-3-methylimidazolium dicyandiamide salt added. Characterization showed that the oxygen atomic content in the waste biomass material after exiting the second drum was 10%. It should be noted that the liquid produced after 3 hours needs to be recycled and injected again.

[0028] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 250mAh / g, initial charge / discharge efficiency 76%; after 100 cycles, the capacity retention rate is still 81%.

[0029] Example 5

[0030] Preparation of carbon materials: 1000g of waste peanut shells were weighed, cut, crushed, and impurities removed. They were then loaded into the first rotating drum of a carbonization kiln. The first rotating drum was heated from room temperature to 80℃ and held for 2 hours. 150g of water vapor was introduced, and simultaneously, 20mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) was injected as a catalyst. After thorough mixing with the biomass fragments, the mixture was conveyed to the second rotating drum. A protective gas (N2) was introduced, the pressure was adjusted to 2MPa, and the temperature was raised to 220℃ at a rate of 5℃ / min, maintained for 4 hours. After further heating to 220℃, 300mL of eluent was injected into the second rotating drum of the carbonization kiln via a liquid pump, and the temperature was maintained for 3 hours. After cooling to room temperature, the final product was obtained. The eluent was a 1:1 volume mixture of 60% sodium carbonate solution and 40% potassium carbonate solution, supplemented with 1% 1-butyl-3-methylimidazolium dicyandiamide salt. Characterization showed that the oxygen atomic content in the waste biomass material after exiting the second drum was 8%. It should be noted that the liquid produced after 4 hours needs to be recycled and injected again.

[0031] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 100mAh / g, initial charge / discharge efficiency 76%; after 100 cycles, 75% capacity retention remains.

[0032] Example 6

[0033] Preparation of carbon materials: 1000g of waste coconut shell biomass was cut, crushed, and impurities removed. It was then loaded into the first rotary drum of a carbonization kiln, which was heated from room temperature to 120℃ and held for 2 hours. 350g of water vapor was introduced, along with 15mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) as a catalyst. After thorough mixing with the biomass fragments, the mixture was conveyed to the second rotary drum. A protective gas (N2) was introduced, and the pressure was adjusted to 2MPa. The temperature was increased to 220℃ at a rate of 5℃ / min and maintained for 4 hours. After reaching 220℃ again, 300mL of leaching solution was injected into the second rotary drum of the carbonization kiln via a liquid pump, and the temperature was maintained for 4 hours. The final product was obtained after cooling to room temperature. The eluent was a mixture of 60% sodium carbonate solution, 40% potassium carbonate solution, and 40% zinc carbonate solution in a 1:1:1 volume ratio, supplemented with 1% 1-butyl-3-methylimidazolium trifluoromethane sulfonate. Characterization showed that the oxygen atomic content in the waste biomass material exiting the second drum was 11%. It should be noted that the liquid generated after 4 hours needs to be recycled and injected again.

[0034] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 236 mAh / g, initial charge / discharge efficiency 80%; after 100 cycles, the capacity retention rate is still 82%.

[0035] Example 7

[0036] Preparation of carbon materials: 1000g of discarded steamed buns were crushed and then loaded into the first rotating drum of a carbonization kiln. The first rotating drum of the carbonization kiln was heated from room temperature to 80℃ and held for 2 hours. 200g of water vapor was introduced, and 10mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) was injected as a catalyst. After being thoroughly mixed with the biomass crushed material, it was conveyed into the second rotating drum. Protective gas N2 was introduced and the pressure was adjusted to 2MPa. The temperature was increased to 500℃ at a rate of 5℃ / min and held for 2 hours. After being heated to 500℃ again, 300mL of eluent was injected into the second rotating drum of the carbonization kiln through a liquid pump and held for 2 hours. After cooling to room temperature, the final product was obtained. The eluent was a 1:1 volume mixture of 60% sodium carbonate solution and 40% potassium carbonate solution, with 5% 1-butyl-3-methylimidazolium dicyandiamide salt added. Characterization showed that the oxygen atomic content in the waste biomass material after exiting the second drum was 10%.

[0037] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 100mAh / g, initial charge / discharge efficiency 77%; after 100 cycles, the capacity retention rate is still 74%.

[0038] Example 8

[0039] Preparation of carbon materials: 1000g of discarded bread was crushed and then loaded into the first rotating drum of a carbonization kiln. The first rotating drum of the carbonization kiln was heated from room temperature to 80℃ and held at this temperature for 1 hour. 100g of water vapor was introduced, and 5mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) was injected as a catalyst. After being thoroughly mixed with the biomass crushed material, it was conveyed into the second rotating drum. Protective gas N2 was introduced and the pressure was adjusted to 2MPa. The temperature was increased to 180℃ at a rate of 5℃ / min. 300mL of eluent was injected into the second rotating drum of the carbonization kiln through a liquid pump, and the pressure was adjusted to a constant 2MPa. 100g of water vapor was added to maintain the temperature at 180℃ and held for 4 hours. After cooling to room temperature, the final product was obtained. The eluent was a 1:1 mixture of 60% sodium carbonate solution and 40% potassium carbonate solution, with the addition of 10% 1-butyl-3-methylimidazolium trifluoromethanesulfonate. Characterization showed that the oxygen atomic content in the waste biomass material after exiting the second drum was 12%.

[0040] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 100mAh / g, initial charge / discharge efficiency 75%; after 100 cycles, the capacity retention rate is still 74%.

[0041] Example 91

[0042] Preparation of carbon materials: 1000g of discarded potatoes were chopped and crushed; then loaded into the first rotating drum of the carbonization kiln. The first rotating drum of the carbonization kiln was heated from room temperature to 110℃ and held at this temperature for 1 hour; 200g of water vapor was introduced, and 10mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) was injected as a catalyst; after being thoroughly mixed with the biomass fragments, the mixture was conveyed into the second rotating drum, and a protective gas N2 was introduced. The pressure was adjusted to 2MPa, and the temperature was increased to 200℃ at a rate of 5℃ / min. Then, 300mL of eluent was injected into the second rotating drum of the carbonization kiln through a liquid pump, and the pressure was adjusted to a constant 2MPa. 100g of water vapor was added, and the temperature was maintained for 4 hours; after cooling to room temperature, the final product was obtained. The eluent was a 1:1 mixture of 60% sodium carbonate solution and 40% potassium carbonate solution, with 15% 1-butyl-3-methylimidazolium trifluoromethanesulfonate added. Characterization showed that the oxygen atomic content in the waste biomass material after exiting the second drum was 15%.

[0043] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 100mAh / g, initial charge / discharge efficiency 85%; after 100 cycles, 80% capacity retention is still maintained.

[0044] Example 10

[0045] Preparation of carbon materials: 1000g of discarded green beans were cut into pieces and crushed. The crushed beans were then loaded into the first rotating drum of a carbonization kiln. The first rotating drum was heated from room temperature to 80℃ and held at that temperature for 1 hour. 150g of water vapor was introduced, along with 15mL of a mixed solution of ferric nitrate (5mol / L) and copper sulfate (5mol / L) as a catalyst. After thorough mixing with the biomass fragments, the mixture was conveyed to the second rotating drum. A protective gas (N2) was introduced, and the pressure was adjusted to 2MPa. The temperature was raised to 200℃, and 400mL of eluent was injected into the second rotating drum using a liquid pump. The pressure was kept constant at 2MPa, and the temperature was maintained for 4 hours. After cooling to room temperature, the final product was obtained. The eluent was a mixture of 60% sodium carbonate solution, 40% potassium carbonate solution, and 40% zinc carbonate solution in a volume ratio of 1:1:1, with the addition of 10% 1-butyl-3-methylimidazolium trifluoromethanesulfonate. Characterization showed that the oxygen atomic content in the waste biomass material after exiting the second drum was 11%.

[0046] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 100mAh / g, initial charge / discharge efficiency 85%; after 100 cycles, 80% capacity retention is still maintained.

[0047] Example 11

[0048] Preparation of carbon materials: 500g of discarded corn cobs and 500g of red mud were weighed and mixed, then loaded into the first rotating drum of the carbonization kiln. The first rotating drum of the carbonization kiln was heated from room temperature to 130℃ and kept at that temperature for 1.5h. 250g of water vapor was introduced, and 20mL of a mixed solution of ferric nitrate (5mol / L concentration) and copper sulfate (5mol / L concentration) was injected as a catalyst. After being thoroughly mixed with the biomass fragments, the mixture was sent to the second rotating drum via a conveyor device. Protective gas N2 was introduced and the pressure was adjusted to 2MPa. The temperature was raised to 800℃ at a rate of 10℃ / min. Then, 300mL of leaching liquid was injected into the second rotating drum of the carbonization kiln through a liquid pump. The pressure was adjusted to a constant 2MPa, and 100g of water vapor was introduced to maintain the temperature and keep it at that temperature for 4h. After cooling to room temperature, the final product was obtained. The leaching solution was a mixture of 60% sodium carbonate solution, 40% potassium carbonate solution, and 30% cobalt carbonate solution in a volume ratio of 1:1:1, with the addition of 20% 1-butyl-3-methylimidazolium dicyandiamide salt. Characterization showed that the oxygen atomic content in the waste biomass material exiting the second rotary drum was 15%.

[0049] Carbon material performance testing: The testing method is the same as in Example 1. Test results: Specific capacity 100mAh / g, initial charge / discharge efficiency 65%; after 100 cycles, the capacity retention rate is still 58%.

Claims

1. A method for preparing a biomass carbon material by a two-stage carbonization kiln process, characterized by: After the biomass material is cut, broken, and impurity-removed, it is loaded into a first rotating drum device of a carbonization kiln, and the first rotating drum of the carbonization kiln is raised from room temperature to 50°C ~ 150°C and kept for 0.5 ~ 2h; water vapor is introduced and mixed with the biomass fragments, which are then sent into a second rotating drum by a conveying device; protective gas N2 is introduced, and the pressure is adjusted to 1 ~ 2MPa; the second rotating drum of the carbonization kiln is raised from room temperature to 150°C ~ 800°C at a rate of 5 ~ 20°C / min; then a leaching solution is sprayed into the second rotating drum, and kept for 2 ~ 4h; after cooling to room temperature, the final product, a biomass carbon material, is obtained; the water vapor is introduced while a catalyst solution is injected; the catalyst is at least one of chloride, sulfate, and nitrate of iron, cobalt, copper, and nickel; the concentration of the catalyst solution is 5 ~ 30%; and the amount of the catalyst solution introduced is 1% ~ 10% of the dry mass fraction of the waste biomass; The amount of water vapor introduced is 5 ~ 30% of the dry mass fraction of the waste biomass; The leaching solution is a mixed solution of two or more carbonates or a mixed solution of a carbonate and an ionic liquid, and the mass concentration of the mixed solution is 30 ~ 60%; The carbonates are sodium carbonate, potassium carbonate, zinc carbonate, cobalt carbonate, and iron carbonate.

2. The method of claim 1, wherein the two-stage carbonization kiln process is characterized by: The biomass material is agricultural and forestry waste, organic kitchen solid waste, or organic sludge.

3. The method of claim 2, wherein the two-stage carbonization kiln process is characterized by: The agricultural and forestry waste is straw, rice straw, fruit shells, and corn cobs.

4. The method of claim 2, wherein the two-stage carbonization kiln process is characterized by: The organic kitchen solid waste is steamed buns, bread, rice, and vegetables.

5. The method of claim 2, wherein the two-stage carbonization kiln process is characterized by: The organic sludge is fecal sludge.

6. The method of claim 1, wherein the two-stage carbonization kiln process is characterized by: The ionic liquid is at least one of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, and 1-butyl-3-methylimidazolium dicyanamide.