Preparation device and method of lignin-based high-conductivity porous carbon

Abstract

The invention provides a preparation device and method of lignin-based high-conductivity porous carbon. The preparation device comprises a pyrolysis module, a heat regulation and control module, an activation module, a post-treatment module and a heat supply module. Wherein the thermal regulation and control module is provided with a carbon defect reactor and is used for carrying out pseudo-graphitization treatment on a pyrolysis product in a high-temperature inert atmosphere to obtain an activated precursor; and the activation module is used for performing alkali activation treatment on the activated precursor in a high-temperature inert atmosphere. According to the preparation method provided by the invention, a large amount of waste lignin of biological refining engineering is taken as a clean and stable carbon supply source, a biomass charcoal precursor is induced to generate directional pseudo-graphitization phase change through a thermal regulation and control module, a carbon microcrystal or amorphous structure of the biomass charcoal precursor is regulated and controlled, and then a high-conductivity network and a hierarchical porous structure are formed through high-temperature alkali activation. The device disclosed by the invention is simple in structure and low in energy consumption, and the prepared porous carbon has the advantage of ultrahigh conductivity and can meet the application requirements of electrochemical energy storage carbon electrodes.

Description

Technical Field

[0001] This invention relates to the field of biomass-based char material preparation technology, specifically to an apparatus and method for preparing lignin-based highly conductive porous char. Background Technology

[0002] Porous carbon, as a carbonaceous functional material with a well-developed pore structure and ultra-high specific surface area, has irreplaceable application value in environmental protection, pharmaceuticals, chemicals, and energy storage. Traditional industrial production of porous carbon mainly relies on non-renewable resources such as coal as raw materials. However, fossil-based raw materials, due to their inherent characteristics such as high structural stability and poor adjustability, cannot meet the precise control requirements of modern energy storage industries for the conductivity and pore structure of activated carbon electrode materials. Lignin, as a major waste product of biorefining processes, has become an ideal precursor for developing high-performance porous carbon due to its wide availability and strong structural designability.

[0003] Biomass-based porous carbon has relatively low intrinsic conductivity, often requiring modification for application in energy devices. However, existing technologies primarily focus on metal doping or modification to improve carbon conductivity. For example, Chinese invention patent CN120157108A discloses a biomass-derived concave hollow porous carbon sphere material, its preparation method, and a battery. This method involves coordinating a metal salt and an amine nucleophile into a pre-prepared biomass-based cellulose solution, applying an external electric field, and then drying and calcining to obtain the biomass-derived concave hollow porous carbon sphere material. This material achieves good conductivity (up to 3320 S / m) by shortening the electron / ion transport path through its unique hollow sphere structure. However, this process uses one or more of aluminum chloride, ferric chloride, and copper chloride as the metal salt, resulting in high costs. Furthermore, it requires an external electric field, making the preparation process complex and energy-intensive, which is not conducive to large-scale utilization. Chinese invention patent CN119640303B discloses a method for enhancing the surface conductivity of biochar, a composite material of biochar loaded with transition metals, and its application. In a hydrothermal reaction, lignocellulose and a solvent containing transition metal ions and nitrogen / oxygen / phosphorus heteroatoms react fully to form a complex precursor. High-temperature calcination then prepares a composite material with a carbon layer and a stable transition metal nanoflower structure. Although this material exhibits high charge transfer capability, its specific surface area is relatively low (only 510.27 m²). 2 / g), limiting its large-scale application; and the metal ions used, such as Mo 5+ Ni 2+ Co 3+ These belong to the category of transition metal ions, are relatively expensive, and pose a potential risk of metal contamination.

[0004] Therefore, there is an urgent need to improve the existing biomass-based porous carbon preparation process and equipment, and to provide a lignin-based high conductivity porous carbon preparation device and method to better meet the needs of electrochemical energy storage applications. Summary of the Invention

[0005] One of the objectives of this invention is to provide an apparatus for preparing lignin-based highly conductive porous carbon.

[0006] The second objective of this invention is to provide a method for preparing lignin-based highly conductive porous carbon.

[0007] One of the technical solutions adopted to achieve the objective of this invention is: to provide a device for preparing lignin-based highly conductive porous carbon, comprising: a pyrolysis module, a thermal regulation module, an activation module, a post-processing module, and a heating module; The pyrolysis module is used to perform stepwise pyrolysis of lignin raw materials, and the outlet of the pyrolysis module is connected to the inlet of the thermal control module. The thermal control module is equipped with a carbon defect reactor, which is used to perform pseudo-graphitization treatment on the pyrolysis products under a high-temperature inert atmosphere to control the carbon microcrystalline or amorphous structure of the carbon precursor and obtain the activated precursor; the solid outlet of the carbon defect reactor is connected to the inlet of the activation module; the activation module is used to perform alkaline activation treatment on the activated precursor under a high-temperature inert atmosphere. The post-processing module is used to process the solid products and exhaust gas; the heating module receives the combustible oil and gas products from the pyrolysis module, the thermal control module and the post-processing module, and provides heat to the preparation device.

[0008] The overall concept and inventive principle of this invention are as follows: The preparation apparatus provided by this invention, through equipment innovation and process optimization, introduces a thermal control module equipped with a carbon defect reactor and an activation module for alkaline activation treatment of the activation precursor, thereby improving the carbon skeleton structure and pore development of the target product and enhancing its electrical conductivity.

[0009] Considering the extremely wide molecular weight distribution of lignin raw materials, high-temperature pyrolysis easily leads to melting and coking. To avoid coking and internal condensation during direct high-temperature pseudo-graphitization of lignin, resulting in insufficient pore development, this invention introduces a stepped pyrolysis module before high-temperature pseudo-graphitization, employing a low-temperature pre-pyrolysis strategy to reduce the O / C ratio and minimize the adverse effects of condensation, coking, or tar formation during the core graphitization reaction on the product. Then, a carbon defect reactor is used to perform pseudo-graphitization treatment on the pyrolysis products under a high-temperature inert atmosphere, achieving control over the microcrystalline or amorphous structure of the carbon precursor to obtain an activated precursor. Finally, an activation module is used to perform alkali activation treatment on the activated precursor under a high-temperature inert atmosphere. This invention, through a combined pyrolysis-activation method, enables the target product to possess the dual advantages of carbon framework construction and pore development, achieving a high specific surface area (>1000 m²) while using lignin as the carbon source. 2 Preparation of carbon materials with high conductivity (>5000 S / m) and high conductivity ( / g).

[0010] Furthermore, the pyrolysis module includes a raw material silo, a screw feeder, and a pyrolysis reactor connected in sequence; the pyrolysis reactor includes a front-end sub-reactor and a rear-end sub-reactor connected in series. The pyrolysis reactor adopts an integrated structural design with two sub-reactors connected in series, which significantly reduces pyrolysis oil and gas loss and improves energy utilization efficiency. Specifically, the lignin raw material in the raw material silo is transported to the pyrolysis reactor via the screw feeder. The pyrolysis reactor achieves stepped heating through a two-stage screw reactor, with the front end heated by heat transfer oil and the rear end heated by phase change heat. The solid outlet of the pyrolysis reactor is connected to the inlet of the carbon defect reactor, and the gas outlet of the pyrolysis reactor is connected to the exhaust gas inlet of the combustion chamber. By timely removing the tar generated by the pyrolysis module, the adverse effects of tar on the morphology and function of porous carbon in the traditional conventional one-step carbonization-activation process are avoided.

[0011] Furthermore, in the thermal control module, the carbon defect reactor provides the main heat in the form of phase change heat, and the temperature is precisely controlled by an electric heating temperature controller with an electric heating coil; the solid outlet of the carbon defect reactor is connected to the inlet of the activation reactor.

[0012] Furthermore, the activation module includes an activator storage silo and an activation reactor. The activation reactor is heated by phase change heat, and the solid outlet of the activation reactor is connected to the inlet of the primary circulating carbon washing tank of the post-processing module.

[0013] Furthermore, the post-processing module includes a primary circulating carbon washing tank, a secondary circulating carbon washing tank, a tertiary circulating carbon washing tank, a spiral dryer, an activated carbon storage silo, an activator recovery pool, a tail gas treatment device, and a flue gas dealkali removal device.

[0014] Furthermore, the gas outlets of the activation reactor and the primary circulating carbon washing tank are connected to the inlet of the flue gas dealkali removal device, and the outlet of the flue gas dealkali removal device is connected to the exhaust gas inlet of the combustion chamber. This invention targets the high-temperature combustible flue gas generated by the activation reactor and the high-temperature alkaline gas generated by the primary circulating carbon washing tank, employing a flue gas dealkali removal device to remove activator components from the combustible gas, reducing corrosion to the combustion chamber. The flue gas dealkali removal device integrates adsorption and chemical fixation technologies, simultaneously achieving alkali metal removal from the activated exhaust gas while minimizing heat loss.

[0015] Furthermore, the liquid outlet of the primary circulating carbon washing tank is connected to an activator recovery tank for the recovery and treatment of the high-concentration alkaline wastewater at the bottom of the primary circulating carbon washing tank. The product after alkali activation treatment passes through the primary, secondary, and tertiary circulating carbon washing tanks in sequence before entering a spiral dryer for drying. After drying, it enters the activated carbon storage silo.

[0016] Furthermore, the heating module includes a combustion chamber, a high-temperature phase change heat storage tank, a medium-temperature phase change heat storage tank, and a heat transfer oil tank. Specifically, the gas outlets at the upper ends of the pyrolysis reactor, the carbon defect reactor, and the flue gas dealkali removal device are connected to the exhaust gas inlet of the combustion chamber. The combustion chamber is equipped with a molten salt pipeline. The combustion chamber uses the heat generated by the combustion of recovered oil and gas to heat the molten salt in the molten salt pipeline. The high-temperature molten salt outlet of the combustion chamber is connected to the high-temperature phase change heat storage tank; the high-temperature phase change heat storage tank provides heat to the carbon defect reactor and the activation reactor.

[0017] Furthermore, the high-temperature flue gas outlet of the combustion chamber is connected to a medium-temperature phase change heat storage box, which provides heat to the downstream terminal reactor of the pyrolysis reactor. The flue gas outlet of the medium-temperature phase change heat storage box is sequentially connected to a heat transfer oil tank, a upstream terminal reactor of the pyrolysis reactor, a spiral dryer, an activator recovery tank, and a tail gas treatment device to achieve cascade utilization of flue gas heat. Specifically, the spiral dryer uses the hot flue gas with residual heat discharged from the upstream terminal reactor of the pyrolysis reactor as a heat source. After drying the solid products, the flue gas with residual heat enters the activator recovery tank and is dried. The resulting secondary activator exists in solid form, which is convenient for storage, transportation, purification, and recycling.

[0018] The preparation apparatus provided by this invention achieves the preparation of lignin-based highly conductive porous carbon while simultaneously considering energy recovery and utilization: the integrated design of the pyrolysis reactor reduces energy loss and heat supply, and the pyrolysis gas produced by the reaction is output to the combustion chamber in a more concentrated manner, which avoids the environmental impact of direct air emission and achieves dual utilization of resources and energy. Simultaneously, the combustible gas at the outlet of the flue gas dealkali removal device is burned together with the pyrolysis gas from the pyrolysis module and the thermal control module. The internal combustion heat is preferentially supplied to the molten salt, which is then transported to the high-temperature phase change heat storage tank. The high-temperature flue gas is supplied to the medium-temperature phase change heat storage tank. Subsequent cascade utilization of heat achieves internal energy circulation within the system, contributing to energy conservation, emission reduction, and efficiency improvement. When the recovered gaseous fuel is insufficient, the missing heat source can be supplemented by externally supplied lignin fuel. The unique heat source and heating method provided by this invention aim to reduce the supply of external electrical or thermal energy and improve economic efficiency.

[0019] The second objective of this invention is achieved by providing a method for preparing lignin-based highly conductive porous carbon, comprising the following steps: S1. The lignin raw material enters the pyrolysis reactor for stepwise pyrolysis, and the generated pyrolysis char enters the carbon defect reactor, while the pyrolysis oil enters the combustion chamber. S2. Pyrolytic carbon undergoes pseudo-graphitization treatment in a carbon defect reactor, and the resulting activated precursor enters the activation reactor, while the gaseous products enter the combustion chamber. S3. The activated precursor is mixed with the activator in the activation reactor and undergoes an alkaline activation reaction in a high-temperature and inert environment to obtain a solid product. The gaseous product enters the flue gas dealkali removal unit. S4. The solid product undergoes post-treatment including washing, drying and collection to obtain highly conductive porous carbon. The combustible gas phase product generated from the post-treatment is transported to the combustion chamber via a flue gas dealkali removal device. The combustion chamber uses the heat generated from the combustion of the recovered oil and gas products to heat the preparation device.

[0020] Further, in step S1, the lignin raw material includes at least one of lignin sulfonate, sulfate lignin, alkali lignin, organic solvent lignin, hydrolyzed lignin, and enzymatically hydrolyzed lignin.

[0021] Preferably, the lignin raw material is enzymatically hydrolyzed lignin prepared by enzymatic hydrolysis in biomass refining. Compared with native biomass materials such as rice husks, straw, and coconut shells, lignin has a very low ash content and a higher C / O ratio, which is beneficial for increasing carbon yield and reducing tar production. Compared with other lignins such as sulfate lignin, alkali lignin, and organic solvent lignin, enzymatically hydrolyzed lignin is retained after decomposing cellulose and hemicellulose in plant cell walls by enzymatic hydrolysis. It has a relatively low molecular weight, a structure closer to natural lignin, and retains more active groups, which is more conducive to functional regulation.

[0022] Further, in step S1, the stepped pyrolysis includes front-end pyrolysis and back-end pyrolysis; the front-end and back-end pyrolysis are carried out in a closed environment using heat transfer oil and phase change heat as heat sources to perform stepped pyrolysis of the lignin raw material. Specifically, the front-end pyrolysis temperature is 340-400℃, and the pyrolysis time is 20-40 min; the back-end pyrolysis temperature is 500-700℃, and the pyrolysis time is 20-40 min. Preferably, the stepped pyrolysis is carried out under an inert atmosphere.

[0023] Further, in step S2, the pseudo-graphitization treatment temperature is 700-1000℃, and the reaction time is 60-90 min. The pseudo-graphitization treatment process uses phase change heat as the main heat source and is precisely controlled by an electric heating temperature controller to heat to a constant temperature for pseudo-graphitization treatment. Preferably, the pseudo-graphitization treatment is carried out under nitrogen protection conditions.

[0024] Further, in step S3, the mass ratio of the activation precursor to the activator is 1:4 to 1:2; the activator is transported to the activation reactor through a feed pipe, and the activator includes one or more combinations of NaOH, Na2CO3, KOH, and K2CO3; the temperature of the alkaline activation reaction is 700-900℃, and the time is 60-120 min. Preferably, the mass ratio of the activation precursor to the activator is 1:3, ensuring that during the alkaline activation treatment stage, the activator moderately corrodes the activation precursor, which can effectively improve the pore structure while avoiding excessive corrosion leading to pore collapse or incomplete pore development.

[0025] Further, in step S4, during the post-processing stage, the solid products sequentially enter the primary circulating carbon washing tank, the secondary circulating carbon washing tank, and the tertiary circulating carbon washing tank for cleaning the carbon products. Solid-liquid separation occurs at the outlet of the tertiary circulating carbon washing tank, and the solid products enter the spiral dryer. Combustible gas that may be generated due to high temperature during the cleaning process in the primary circulating carbon washing tank is transported to the flue gas dealkali removal device through the gas outlet. Subsequently, the gaseous products of the flue gas dealkali removal device enter the combustion chamber.

[0026] Further, in step S4, the pyrolysis oil-gas mixture generated inside the preparation device enters the combustion chamber for combustion. The heat generated by combustion first heats the molten salt inside the combustion chamber to supply heat to the high-temperature phase change heat storage tank, and then heats the carbon defect reactor and the activation reactor. The hot flue gas generated in the combustion chamber is used to heat the medium-temperature phase change heat storage tank, which first heats the rear end of the pyrolysis reactor. The hot flue gas then heats the heat transfer oil tank and the front end of the pyrolysis reactor. The remaining heat is supplied to the spiral dryer and the activator recovery tank for drying activated carbon and wastewater containing activator, thereby realizing the recovery of activator.

[0027] Furthermore, in step S4, during the heating process, the working temperature of the high-temperature phase change heat storage box is set to 700-900℃, the working temperature of the medium-temperature phase change heat storage box is set to 550-650℃, and the working temperature of the heat transfer oil box is set to 350-400℃.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides an apparatus and method for preparing lignin-based highly conductive porous carbon, which addresses the problems of low conductivity and low specific surface area of ​​traditional activated carbon by setting up a thermal control module and an activation module. The carbon defect reactor in the thermal control module can perform targeted high-temperature pseudo-graphitization treatment on the pyrolytic carbon, completing the directional control of the carbon precursor carbon microcrystals or amorphous structures, forming a porous carbon with sp... 2 The carbon structure is mainly hybridized, and then the activation precursor is activated by alkaline activation using an activation module, which achieves a dual improvement in the specific surface area and conductivity of activated carbon.

[0029] (2) The present invention provides a lignin-based high-conductivity porous carbon preparation device and method, which simultaneously achieves the preparation of lignin-based high-conductivity porous carbon and takes into account energy recovery and utilization: the front and rear sections of the pyrolysis module are connected, and the combustible oil gas generated at the front end is finally transported to the combustion chamber through the rear end, which can avoid the impact of direct air emission on the environment and achieve dual utilization of resources and energy; the fuel sources of the combustion chamber mainly include the oil and gas products of the pyrolysis module, the thermal control module and the flue gas dealkalization device. The pyrolysis oil and gas and the dealkalization activation gas are introduced into the combustion chamber for combustion, and the system realizes the self-sustaining supply of heat energy, forming a closed-loop energy cycle mechanism. The heat generated by combustion in the combustion chamber preferentially heats the internal molten salt and supplies the high-temperature molten salt to the high-temperature phase change heat storage box, while the hot flue gas supplies the medium-temperature phase change heat storage box. The high-temperature phase change heat storage box provides heat for the carbon defect reactor and the activation reactor; the high-temperature flue gas is connected in sequence to the heat transfer oil tank, the front terminal reactor of the pyrolysis reactor, the spiral dryer, the activator recovery tank and the tail gas treatment device through the flue gas outlet of the medium-temperature phase change heat storage box. The preparation device and method of the present invention adopts a unique heat source and heating method, realizes the internal circulation of system energy, can significantly reduce the supply of external electrical or thermal energy, and improve economic efficiency. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of a lignin-based highly conductive porous carbon preparation device provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the pyrolysis reactor in the preparation apparatus provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the thermal carbon defect reactor in the preparation apparatus provided in an embodiment of the present invention; Figure 4This is a schematic diagram of the activation reactor in the preparation apparatus provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the primary circulating carbon washing tank in the preparation apparatus provided in the embodiment of the present invention; Figure 6 This is a schematic diagram of the spiral dryer in the preparation apparatus provided in the embodiment of the present invention; Figure 7 This is a schematic diagram of the combustion chamber in the preparation apparatus provided in an embodiment of the present invention; Figure 8 This is a scanning electron microscope image of the activated precursor obtained by pseudo-graphitization treatment at 900℃ in Example 1 of the present invention; Figure 9 This is a scanning electron microscope image of the porous carbon prepared by pseudo-graphitization treatment and alkali activation treatment at 900℃ in Example 1 of the present invention. Figure 10 The electrical conductivity of the activated precursor obtained by pseudo-graphitization treatment under different temperature conditions in Example 1 of this invention is a curve showing the change in electrical conductivity with pressure. Figure 11 The electrical conductivity curve of porous carbon obtained by pseudo-graphitization and alkali activation treatment in Example 1 of this invention is a curve showing the change of electrical conductivity with pressure. The components are as follows: 1. Raw material silo; 2. Screw feeder; 3. Pyrolysis reactor; 3-1. Motor; 3-2. Lignin raw material inlet; 3-3. Conveying screw; 3-4. Insulation jacket of pyrolysis reactor; 3-5. Gas outlet; 3-6. Solid outlet; 3-7. Front end of pyrolysis reactor; 3-8. Rear end of pyrolysis reactor; 4. Carbon defect reactor; 4-1. Electric heating temperature controller; 4-2. Inlet of hot carbon defect reactor; 4-3. Motor; 4-4. Gas outlet; 4-5. Insulation jacket; 4-6. Solid outlet; 4-7. Conveying screw; 4-8. Electric heating coil; 5. Activator storage silo; 6. Activation reactor; 6-1. Shell; 6-2. Activator inlet of activation reactor; 6-3. Activation precursor inlet; 6-4. Motor; 6-5. Gas outlet; 6-6. Solid outlet; 6-7. 7. Agitator; 8. Primary circulating carbon washing tank; 7-1. Tank body; 7-2. Solid outlet of carbon washing tank; 7-3. Tank inlet; 7-4. Gas outlet; 7-5. Liquid outlet; 7-6. Liquid inlet; 9. Secondary circulating carbon washing tank; 10. Spiral dryer; 10-1. Motor; 10-2. Insulation jacket of spiral dryer; 10-3. Material inlet; 10-4. Conveying screw; 10-5. Solid outlet; 11. Activated carbon storage silo; 12. Activator recovery tank; 13. Tail gas treatment device; 14. Combustion chamber; 14-1. Tail gas inlet; 14-2. Molten salt inlet; 14-3. High-temperature flue gas outlet; 14-4. High-temperature molten salt outlet; 15. High-temperature phase change heat storage box; 16. Medium-temperature phase change heat storage box; 17. Heat transfer oil box; 18. Flue gas dealkalization device. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0033] Please see Figure 1-7 This invention provides an apparatus for preparing lignin-based highly conductive porous carbon, including a pyrolysis module, a thermal regulation module, an activation module, a post-processing module, and a heating module.

[0034] The pyrolysis module includes a raw material silo 1, a screw feeder 2, and a pyrolysis reactor 3. The outlet of the raw material silo 1 is connected to the inlet of the screw feeder 2, and the outlet of the screw feeder 2 is connected to the inlet 3-2 of the pyrolysis reactor.

[0035] like Figure 2 As shown, the pyrolysis reactor consists of a motor 3-1, a lignin raw material inlet 3-2, a conveying screw 3-3, a pyrolysis reactor insulation jacket 3-4, a gas outlet 3-5, a solid outlet 3-6, a pyrolysis reactor front end 3-7, and a pyrolysis reactor rear end 3-8. The pyrolysis reactor 3 is used for the pyrolysis of lignin raw materials. It has an internal conveying screw 3-3, driven by the motor 3-1. The time the lignin raw material spends in the reactor is controlled by adjusting the speed of the conveying screw 3-3. The insulation jacket 3-4 of the pyrolysis reactor 3 is used to ensure that the internal temperature of the reactor remains constant. The pyrolysis oil and gas generated at the pyrolysis reactor front end 3-7 and the pyrolysis reactor rear end 3-8 are transported to the combustion chamber 14 through the gas outlet 3-5.

[0036] like Figure 3 As shown, the thermal control module includes a carbon defect reactor 4, which consists of an electric heating temperature controller 4-1, a thermal carbon defect reactor inlet 4-2, a screw motor 4-3, a gas outlet 4-4, an insulation jacket 4-5, a solid outlet 4-6, a conveying screw 4-7, and an electric heating coil 4-8. The carbon defect reactor 4 achieves control over the microcrystalline or amorphous structure of the pyrolyzed carbon precursor through pseudo-graphitization treatment at high temperatures. Its interior is equipped with a conveying screw 4-7 driven by the motor 4-3. Adjusting the speed of the conveying screw 4-7 controls the time the solid spends in the reactor. The insulation jacket 4-5 is connected to a high-temperature phase change heat storage tank 15, through which high-temperature molten salt is introduced to provide the heat required for the pseudo-graphitization treatment. The temperature is controlled by the electric heating temperature controller to reach and maintain a constant temperature. The combustible oil gas generated during the pseudo-graphitization process is input into the combustion chamber 14 through the gas outlet 4-4.

[0037] like Figure 4 As shown, the activation module includes an activator storage silo 5 and an activation reactor 6. The activation reactor 6 consists of a shell 6-1, an activator inlet 6-2, an activation precursor inlet 6-3, a motor 6-4, a gas outlet 6-5, a solid outlet 6-6, and a stirrer 6-7. The activation reactor precursor inlet 6-3 is connected to the carbon defect reactor outlet 4-6, and the activator inlet 6-2 is connected to the activator storage silo 5 for inputting the activator. The outer shell of the activation reactor 6 is composed of an insulation layer, and a high-temperature molten salt pipeline is laid inside, which is heated by a high-temperature phase change heat storage box 15. During operation, the motor 6-4 drives the stirrer 6-7 to stir the mixture, and the temperature inside the reactor is kept relatively uniform through the jacket insulation, resulting in a more uniform reaction. The reacted material is discharged to the primary circulating carbon washing tank 7 through the solid outlet 6-6, and the combustible oil gas generated during the reaction is input into the flue gas dealkali removal device 18 through the gas outlet 6-5 and then transported to the combustion chamber 14.

[0038] The post-processing module includes a primary circulating carbon washing tank 7, a secondary circulating carbon washing tank 8, a tertiary circulating carbon washing tank 9, a spiral dryer 10, an activated carbon storage silo 11, and an activator recovery tank 12.

[0039] like Figure 5 As shown, the primary circulating carbon washing tank includes a tank body 7-1, a solid outlet 7-2, a tank inlet 7-3, a gas outlet 7-4, a liquid outlet 7-5, and a liquid inlet 7-6. The secondary and tertiary circulating carbon washing tanks 8 and 9 do not have unidirectional gas outlets; their remaining structures are identical to the primary circulating carbon washing tank 8. The tank inlet 7-3 connects to the solid outlet 6-6 of the activation reactor for inputting the hot reacted material; the liquid inlet 7-6 connects to the liquid outlet of the secondary circulating carbon washing tank for inputting the washed liquid; the solid outlet 7-2 connects to the solid inlet of the secondary circulating carbon washing tank for secondary washing of the reacted material, which is then input into the tertiary circulating carbon washing tank for a final wash. After solid-liquid separation in the tertiary circulating carbon washing tank, the solid product enters the spiral dryer 10 for drying and is temporarily stored in the activated carbon storage silo 11. During the cleaning process, the combustible oil gas that may be generated due to high temperature in the primary circulating carbon washing tank is input into the flue gas dealkali device through the one-way gas outlet 7-4 and then transported to the combustion chamber 14 for combustion; the waste liquid is transported to the activator recovery tank 12 through the liquid outlet 7-5, and the remaining tail gas heat is used to evaporate and recover the activator.

[0040] The heating module consists of an exhaust gas treatment device 13, a combustion chamber 14, a high-temperature phase change heat storage box 15, a medium-temperature phase change heat storage box 16, a heat transfer oil box 17, and a flue gas dealkali removal device 18.

[0041] like Figure 7 As shown, the combustion chamber 14 is equipped with an exhaust gas inlet 14-1, a molten salt inlet 14-2, a high-temperature flue gas outlet 14-3, and a high-temperature molten salt outlet 14-4. The heat generated by combustion in the combustion chamber 14 preferentially heats the internal molten salt, which is then supplied to the high-temperature phase change heat storage tank 15, and subsequently to the carbon defect reactor 4 and the activation reactor 6. The heat from the flue gas generated in the combustion chamber is supplied to the medium-temperature phase change heat storage tank 16, and the remaining hot flue gas heat is sequentially supplied to the heat transfer oil tank 17, the front end of the pyrolysis reactor 3, the spiral dryer 10, and the activator recovery tank 12 for drying activated carbon and recovering the activator. The medium-temperature phase change heat storage tank 16 heats the rear end of the pyrolysis reactor 3.

[0042] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0043] In various embodiments of the present invention, the lignin used is enzymatically hydrolyzed lignin prepared by enzymatic hydrolysis process in biomass refining (decomposing cellulose and hemicellulose in plant cell walls by enzymatic hydrolysis).

[0044] Example 1 This invention provides a method based on Figure 1-7 The method for preparing lignin-based highly conductive porous carbon using the provided preparation apparatus includes the following steps: Step 1: The lignin raw material enters the pyrolysis reactor and undergoes staged pyrolysis under an inert atmosphere. The staged pyrolysis includes a front-end pyrolysis and a back-end pyrolysis. The front-end pyrolysis temperature is set at 380℃ for 30 minutes, using heat transfer oil as the heat source. The back-end pyrolysis temperature is set at 600℃ for 30 minutes, using phase change heat as the heat source. The pyrolytic char generated after staged pyrolysis enters the carbon defect reactor, and the pyrolysis oil and gas enter the combustion chamber. Step 2: In the carbon defect reactor, the pyrolytic carbon is heated to a constant temperature (700℃, 800℃, 900℃ and 1000℃ respectively) in an inert atmosphere using phase change heat as the main heat source and precise control using an electric heating temperature controller. The carbon is then subjected to pseudo-graphitization treatment for 60 minutes. The resulting activated precursor enters the activation reactor, and the gaseous products enter the combustion chamber. Step 3: The activation precursor is thoroughly mixed with the activator KOH in the activation reactor at a mass ratio of 1:3, and the alkaline activation reaction is carried out at 800℃ under an inert atmosphere for 90 min to obtain a solid product. The gaseous product enters the flue gas dealkali removal unit. Step 4: The solid product is sequentially fed into the primary circulating carbon washing tank, the secondary circulating carbon washing tank, and the tertiary circulating carbon washing tank for cleaning. Solid-liquid separation is performed at the outlet of the tertiary circulating carbon washing tank. The solid product is then thoroughly dried in a spiral dryer. The resulting highly conductive porous carbon is collected in an activated carbon storage silo.

[0045] Furthermore, in the above preparation method, the combustible gas generated by the high temperature during the cleaning process in the primary circulating carbon washing tank is transported to the flue gas dealkali removal device via the gas outlet. Subsequently, the gaseous products of the flue gas dealkali removal device enter the combustion chamber. The combustion chamber collects and combusts the pyrolysis oil-gas mixture generated inside the preparation device. The heat generated preferentially heats the molten salt inside the combustion chamber. The high-temperature molten salt is supplied to the high-temperature phase change heat storage tank, which is then used to heat the carbon defect reactor and the activation reactor. The high-temperature hot flue gas generated in the combustion chamber is supplied to the medium-temperature phase change heat storage tank. The medium-temperature phase change heat storage tank first heats the rear end of the pyrolysis reactor, and then the hot flue gas heats the heat transfer oil tank and the front end of the pyrolysis reactor. The remaining heat is supplied to the spiral dryer and the activator recovery tank for drying activated carbon and wastewater containing activator.

[0046] Table 1 shows the specific surface area and pore structure of the activated precursors after pseudo-graphitization treatment under different temperature conditions in Example 1.

[0047] Table 1

[0048] Figure 8 This is a scanning electron microscope (SEM) image of the activated precursor in Example 1 after pseudo-graphitization treatment at 900°C. Figure 8As shown, after pseudo-graphitization treatment at 900℃, the activated precursor exhibits a low degree of pore structure development on its surface, lacking both macropores and mesopores. Simultaneously, its morphology displays a coexistence of spherical large particles and linear fibers. This phenomenon is attributed to the partial melting of the spherical particles during the high-temperature treatment, resulting in incomplete melting and causing some carbon particles to adhere to the carbon surface in a molten state. Meanwhile, the fibrous carbon, due to its higher thermal stability, did not undergo significant morphological changes at high temperatures.

[0049] Figure 9 The image shows a scanning electron microscope (SEM) image of the porous carbon obtained after the above-mentioned activated precursor undergoes alkaline activation treatment in step 3. The comparison reveals that the carbon product exhibits a distinct porous structure after high-temperature alkaline activation treatment, with a significant increase in the number of surface pores. Furthermore, the coexistence of macropores and mesopores is observed, which facilitates electron flow and enhances electrical conductivity.

[0050] Example 2 This invention provides a method based on Figure 1-7 The method for preparing lignin-based highly conductive porous carbon using the provided preparation apparatus includes the following steps: Step 1: The lignin raw material enters the pyrolysis reactor and undergoes staged pyrolysis under an inert atmosphere. The staged pyrolysis includes a front-end pyrolysis and a back-end pyrolysis. The front-end pyrolysis temperature is set at 340℃ for 40 minutes, using heat transfer oil as the heat source. The back-end pyrolysis temperature is set at 700℃ for 20 minutes, using phase change heat as the heat source. The pyrolytic char generated after staged pyrolysis enters the carbon defect reactor, and the pyrolysis oil and gas enter the combustion chamber. Step 2: In the carbon defect reactor, the pyrolytic carbon is heated to 900°C in an inert atmosphere with phase change heat as the main heat source and electric heating temperature controller for precise control. It is then subjected to pseudo-graphitization treatment for 60 minutes. The resulting activated precursor enters the activation reactor, and the gaseous products enter the combustion chamber. Step 3: The activation precursor is thoroughly mixed with the activator NaOH in the activation reactor at a mass ratio of 1:2, and the alkaline activation reaction is carried out at 700℃ under an inert atmosphere for 120 min to obtain the solid product. The gaseous product enters the flue gas dealkali removal unit. Step 4: The solid product is sequentially fed into the primary circulating carbon washing tank, the secondary circulating carbon washing tank, and the tertiary circulating carbon washing tank for cleaning. Solid-liquid separation is performed at the outlet of the tertiary circulating carbon washing tank. The solid product is then thoroughly dried in a spiral dryer. The resulting highly conductive porous carbon is collected in an activated carbon storage silo.

[0051] Furthermore, in the above preparation method, the combustible gas generated by the high temperature during the cleaning process in the primary circulating carbon washing tank is transported to the flue gas dealkali removal device via the gas outlet. Subsequently, the gaseous products of the flue gas dealkali removal device enter the combustion chamber. The combustion chamber collects and combusts the pyrolysis oil-gas mixture generated inside the preparation device. The heat generated preferentially heats the molten salt inside the combustion chamber. The high-temperature molten salt is supplied to the high-temperature phase change heat storage tank, which is then used to heat the carbon defect reactor and the activation reactor. The high-temperature hot flue gas generated in the combustion chamber is supplied to the medium-temperature phase change heat storage tank. The medium-temperature phase change heat storage tank first heats the rear end of the pyrolysis reactor, and then the hot flue gas heats the heat transfer oil tank and the front end of the pyrolysis reactor. The remaining heat is supplied to the spiral dryer and the activator recovery tank for drying activated carbon and wastewater containing activator.

[0052] Example 3 This invention provides a method based on Figure 1-7 The method for preparing lignin-based highly conductive porous carbon using the provided preparation apparatus includes the following steps: Step 1: The lignin raw material enters the pyrolysis reactor and undergoes staged pyrolysis under an inert atmosphere. The staged pyrolysis includes a front-end pyrolysis and a back-end pyrolysis. The front-end pyrolysis temperature is set at 400℃ for 20 minutes, using heat transfer oil as the heat source. The back-end pyrolysis temperature is set at 500℃ for 40 minutes, using phase change heat as the heat source. The pyrolytic char generated after staged pyrolysis enters the carbon defect reactor, and the pyrolysis oil and gas enter the combustion chamber. Step 2: In the carbon defect reactor, the pyrolytic carbon is heated to 900°C in an inert atmosphere with phase change heat as the main heat source and electric heating temperature controller for precise control. The carbon is then subjected to pseudo-graphitization treatment for 90 minutes. The resulting activated precursor enters the activation reactor, and the gaseous products enter the combustion chamber. Step 3: The activation precursor is thoroughly mixed with the activator K2CO3 in the activation reactor at a mass ratio of 1:4, and the alkaline activation reaction is carried out at 900℃ under an inert atmosphere for 60 min to obtain the solid product. The gaseous product enters the flue gas dealkali removal unit. Step 4: The solid product is sequentially fed into the primary circulating carbon washing tank, the secondary circulating carbon washing tank, and the tertiary circulating carbon washing tank for cleaning. Solid-liquid separation is performed at the outlet of the tertiary circulating carbon washing tank. The solid product is then thoroughly dried in a spiral dryer. The resulting highly conductive porous carbon is collected in an activated carbon storage silo.

[0053] Furthermore, in the above preparation method, the combustible gas generated by the high temperature during the cleaning process in the primary circulating carbon washing tank is transported to the flue gas dealkali removal device via the gas outlet. Subsequently, the gaseous products of the flue gas dealkali removal device enter the combustion chamber. The combustion chamber collects and combusts the pyrolysis oil-gas mixture generated inside the preparation device. The heat generated preferentially heats the molten salt inside the combustion chamber. The high-temperature molten salt is supplied to the high-temperature phase change heat storage tank, which is then used to heat the carbon defect reactor and the activation reactor. The high-temperature hot flue gas generated in the combustion chamber is supplied to the medium-temperature phase change heat storage tank. The medium-temperature phase change heat storage tank first heats the rear end of the pyrolysis reactor, and then the hot flue gas heats the heat transfer oil tank and the front end of the pyrolysis reactor. The remaining heat is supplied to the spiral dryer and the activator recovery tank for drying activated carbon and wastewater containing activator.

[0054] Conductivity test According to the conductivity meter test method of GB / T11007-2008, the conductivity properties of the activated precursor (after pseudo-graphitization treatment) and porous carbon material (after pseudo-graphitization treatment and alkali activation treatment) prepared in Example 1 under different temperature conditions were tested using the four-probe method.

[0055] First, the material powder was pressed into discs with a diameter of 30 mm and a thickness of approximately 1 mm under a pressure of 20 MPa. A resistivity meter equipped with four equally spaced (s = 1 mm) probes was used. The test was conducted at room temperature, with a constant DC current (I = 1 mA) applied through the two outer probes, and the voltage drop (V) between the two inner probes was measured. The conductivity (σ) was calculated using the following formula:

[0056] Where t is the sample thickness (m), S is the probe spacing (m), and k is the correction factor (determined by calibration).

[0057] like Figure 10 As shown, the conductivity of the activated precursor treated with pseudo-graphitization under different temperature conditions increases with the increase of disorder, but the conductivity is below 1000 S / m.

[0058] like Figure 11 As shown, the conductivity of the porous carbon obtained after alkali activation was significantly improved, all exceeding 5000 S / m, and the sample treated with pseudo-graphitization at 900℃ exhibited the highest conductivity, at 6213 S / m (20 MPa). This is because the alkali-activated carbon material possesses a high specific surface area and a rich layered pore structure, forming a good conductive network. Simultaneously, the increased pressure leads to a reduction in the gaps between particles and an increase in the contact between particles, which further promotes the improvement in conductivity.

[0059] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. An apparatus for preparing lignin-based highly conductive porous carbon, characterized in that, include: The module consists of a pyrolysis module, a thermal control module, an activation module, a post-processing module, and a heating module. The pyrolysis module is used to perform stepwise pyrolysis of lignin raw materials, and the outlet of the pyrolysis module is connected to the inlet of the thermal control module. The thermal control module is equipped with a carbon defect reactor (4), which is used to perform pseudo-graphitization treatment on the pyrolysis products under a high temperature inert atmosphere to achieve the control of the carbon precursor carbon microcrystal or amorphous structure and obtain the activated precursor; the solid outlet of the carbon defect reactor is connected to the inlet of the activation module; the activation module is used to perform alkaline activation treatment on the activated precursor under a high temperature inert atmosphere. The post-processing module is used to process the solid products and exhaust gas; the heating module receives the combustible oil and gas products from the pyrolysis module, the thermal control module and the post-processing module, and provides heat to the preparation device.

2. The apparatus for preparing lignin-based highly conductive porous carbon according to claim 1, characterized in that, The pyrolysis module includes a raw material silo (1), a screw feeder (2), and a pyrolysis reactor (3) connected in sequence. The pyrolysis reactor (3) includes a front terminal reactor and a rear terminal reactor connected in series. The solid outlet of the pyrolysis reactor (3) is connected to the inlet of the carbon defect reactor (4), and the gas outlet of the pyrolysis reactor (3) is connected to the exhaust gas inlet of the combustion chamber (14) in the heating module.

3. The apparatus for preparing lignin-based highly conductive porous carbon according to claim 2, characterized in that, The activation module includes an activator storage bin (5) and an activation reactor (6); The post-processing module includes a primary circulating carbon washing tank (7), a secondary circulating carbon washing tank (8), a tertiary circulating carbon washing tank (9), a spiral dryer (10), an activated carbon storage silo (11), an activator recovery tank (12), a tail gas treatment device (13), and a flue gas dealkali removal device (18). The gas outlets of the activation reactor (6) and the primary circulating carbon washing tank (7) are connected to the inlet of the flue gas dealkali removal device (18), and the outlet of the flue gas dealkali removal device (18) is connected to the tail gas inlet of the combustion chamber (14).

4. The apparatus for preparing lignin-based highly conductive porous carbon according to claim 3, characterized in that, The heating module includes a combustion chamber (14), a high-temperature phase change heat storage box (15), a medium-temperature phase change heat storage box (16), and a heat transfer oil box (17). The combustion chamber (14) is equipped with a molten salt pipe, and the high-temperature molten salt outlet of the combustion chamber (14) is connected to a high-temperature phase change heat storage box (15); the high-temperature phase change heat storage box (15) provides heat for the carbon defect reactor (4) and the activation reactor (6).

5. The apparatus for preparing lignin-based highly conductive porous carbon according to claim 4, characterized in that, The high-temperature flue gas outlet of the combustion chamber (14) is connected to the medium-temperature phase change heat storage box (16), which is used to provide heat to the downstream terminal reactor of the pyrolysis reactor (3). The flue gas outlet of the medium-temperature phase change heat storage box (16) is connected in sequence to the heat transfer oil tank (17), the front terminal reactor of the pyrolysis reactor (3), the spiral dryer (10), the activator recovery tank (12), and the tail gas treatment device (13).

6. A method for preparing lignin-based highly conductive porous carbon using a preparation apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: S1. The lignin raw material enters the pyrolysis reactor (3) for stepwise pyrolysis, and the generated pyrolysis char enters the carbon defect reactor (4), while the pyrolysis oil and gas enter the combustion chamber (14). S2. Pyrolytic carbon undergoes pseudo-graphitization treatment in carbon defect reactor (4), and the resulting activated precursor enters activation reactor (6), while the gaseous products enter combustion chamber (14). S3. The activated precursor is mixed with the activator in the activation reactor (6) and undergoes alkaline activation reaction in a high temperature and inert environment to obtain a solid product. The gaseous product enters the flue gas dealkali removal device (18). S4. The solid phase product is subjected to post-treatment including washing, drying and collection to obtain highly conductive porous carbon. The combustible gas phase product generated by the post-treatment is transported to the combustion chamber (14) through the flue gas dealkali device (18). The combustion chamber (14) generates heat by burning the recovered oil and gas products and provides heat for the preparation device.

7. The preparation method according to claim 6, characterized in that, In step S1, the lignin raw material includes at least one of lignin sulfonate, sulfate lignin, alkali lignin, organic solvent lignin, hydrolyzed lignin, and enzymatically hydrolyzed lignin.

8. The preparation method according to claim 6, characterized in that, In step S1, the cascade pyrolysis includes front-end pyrolysis and back-end pyrolysis; the temperature of the front-end pyrolysis is 340-400℃ and the pyrolysis time is 20-40 min; the temperature of the back-end pyrolysis is 500-700℃ and the pyrolysis time is 20-40 min.

9. The preparation method according to claim 6, characterized in that, In step S2, the temperature for pseudo-graphitization treatment is 700-1000℃, and the reaction time is 60-90 min.

10. The preparation method according to claim 6, characterized in that, In step S3, the mass ratio of the activation precursor to the activator is 1:4 to 1:2; the activator includes one or more combinations of NaOH, Na2CO3, KOH, and K2CO3; the activation reaction temperature is 700-900℃, and the reaction time is 60-120 min.

Images