A porous carbon activation method based on carrier particle recycling

Abstract

This invention relates to the field of porous carbon material preparation technology, and particularly to a method for activating porous carbon based on carrier particle circulation. The method includes: pneumatically conveying carbon raw material heated by a raw material heating unit to a fluidized bed reaction unit using inert gas; continuously and stably inputting heat-carrying particles heated by a first heating unit into the fluidized bed reaction unit; introducing activation gas and carrier gas into the fluidized bed reaction unit through an activation gas supply unit at a predetermined mixing ratio to form a stable fluidized bed layer between the heat-carrying particles and the carbon raw material; separating the porous carbon, which has undergone activation under preset activation conditions, from the heat-carrying particles; and conveying the porous carbon to a discharge cooling unit at a predetermined temperature using inert gas. This invention achieves significant improvement in temperature field control accuracy and reduces the bed temperature difference to ±5℃ through systemic synergistic innovation of dynamic heat transfer via heat-carrying particle circulation, steam / CO2 graded activation, and closed-loop tail gas energy.

Description

Technical Field

[0001] This invention relates to the field of porous carbon material preparation technology, and in particular to a method for activating porous carbon based on carrier particle recycling. Background Technology

[0002] Against the backdrop of the rapid development of new energy vehicles and energy storage technologies, lithium-ion batteries are placing higher demands on the capacity, cycle life, and stability of anode materials. While silicon-based anode materials possess a theoretical capacity ten times that of graphite, their significant volume expansion leads to a sharp decline in cycle performance. Constructing silicon-carbon anode materials by loading nano-silicon onto a porous carbon matrix using chemical vapor deposition and then carbon coating has become the most promising technological approach. As a precursor to silicon-carbon anode materials, the pore structure of porous carbon directly determines the uniformity of silicon dispersion and its expansion buffering capacity—a specific surface area exceeding 1500 m² / g is required to provide sufficient loading sites, while also possessing gradient channels (micropores adsorbing silicon particles, mesopores relieving expansion stress). This places unprecedentedly stringent requirements on the preparation process of porous carbon.

[0003] Current mainstream physical activation processes generally suffer from an inherent contradiction between temperature field control and energy efficiency. During fluidized bed activation, ultrafine carbon powder (<10μm) is prone to agglomeration due to van der Waals forces, leading to localized temperature deviations exceeding ±50℃ within the bed, causing excessive micropore ablation or incomplete activation. This temperature inhomogeneity directly manifests as product specific surface area fluctuations of ±200m² / g, with significant batch-to-batch differences in pore distribution, severely impacting the performance consistency of silicon-carbon anodes. Simultaneously, the activation reaction must be continuously carried out at high temperatures of 800-1100℃. Traditional equipment suffers from severe heat loss, resulting in a thermal energy utilization rate of less than 40%, with approximately 35% of the heat lost through the reactor wall and over 25% of the energy directly emitted with the high-temperature exhaust gas, resulting in persistently high production costs.

[0004] While existing technologies attempt to alleviate these problems through equipment improvements or process optimizations, they do not address the fundamental issues. Conventional fluidized beds use a single heat source, making it difficult to maintain axial and radial temperature equilibrium during scale-up production, especially when processing low thermal conductivity carbon materials, where the temperature difference between the bed center and edge can exceed 100°C. Simply extending the activation time to increase specific surface area not only reduces the yield to below 20% but also leads to a significant increase in energy consumption. Regarding pore size control, traditional processes use a fixed-ratio mixing of activation gases. Due to the difference in reaction kinetics between water vapor and CO2, this easily leads to a hybrid structure with an imbalanced ratio of micropores to mesopores, making it difficult to meet the precise pore structure requirements of silicon-carbon anodes.

[0005] Traditional processes result in uneven heat transfer, leading to large temperature differences in the bed layer, which in turn causes large fluctuations in the specific surface area of ​​the product and poor performance consistency between batches. Summary of the Invention

[0006] Therefore, the present invention provides a porous carbon activation method based on carrier particle circulation to overcome the problems in the existing technology where uneven heat transfer leads to large temperature differences in the bed, resulting in large fluctuations in the specific surface area of ​​the product and poor performance consistency between batches.

[0007] To achieve the above objectives, the present invention provides a method for activating porous carbon based on carrier particle recycling, comprising:

[0008] Inert gas is used to pneumatically transport the carbon feedstock heated by the feedstock heating unit to the fluidized bed reaction unit;

[0009] The heat-carrying particles heated by the first heating unit are continuously and stably fed into the fluidized bed reaction unit;

[0010] The activation gas and carrier gas are introduced into the fluidized bed reaction unit through the activation gas supply unit in a predetermined mixing ratio so that the heat-carrying particles and the carbon raw material form a stable fluidized bed.

[0011] The porous carbon that has completed the activation reaction under preset activation conditions is separated from the heat-carrying particles. The porous carbon is transported to the unloading cooling unit by inert gas at a predetermined temperature. The heat-carrying particles are returned to the first heating unit for cyclic heating and reuse through the heat-carrying particle conveying unit.

[0012] The activated porous carbon product is discharged to the product unloading and cooling unit under inert gas protection at a high temperature of 600±50℃, and cooled to below 50℃ to obtain the porous carbon product.

[0013] The reaction tail gas from the activation reaction is partially returned to the activation gas supply unit via the tail gas recirculation unit, with a proportion of 20-80% vol%.

[0014] After the heat-carrying particles have been used for a preset cycle time, they are exported and regenerated in an oxidizing atmosphere.

[0015] The activation gas is one or a combination of water vapor and CO2, the preset activation conditions include a preset activation temperature and a preset activation time, and the porous carbon is a product prepared from carbon raw materials that have undergone an activation reaction.

[0016] The fluidized bed reaction unit is heated by either electric heating or natural gas combustion heating, preferably electric heating.

[0017] Furthermore, the carbon raw material is one or more of biochar, petroleum coke, phenolic resin, and pitchblende.

[0018] The carbon raw material has a particle size range of 2-10 μm and a specific surface area of ​​≤400 m² / g.

[0019] Furthermore, the temperature range for heating the carbon raw material by the raw material heating unit is 300-700℃, and the temperature range for heating the heat-carrying particles by the first heating unit is 900-1000℃.

[0020] Furthermore, the carrier particles are one or more of alumina, silicon dioxide, and metal particles;

[0021] The particle size of the heat-carrying particles is ≤300μm.

[0022] Furthermore, the heat-carrying particles are spherical particles with a particle size of 80-120 μm.

[0023] Furthermore, the mass ratio of the heat-carrying particles to the carbon raw material in the fluidized bed reaction unit is less than or equal to 5, preferably in the range of 0.5-2.

[0024] A valve for controlling the heat carrier circulation rate is provided between the first heating unit and the fluidized bed reaction unit.

[0025] Furthermore, the preset activation conditions include a first preset activation condition and a second preset activation condition;

[0026] The first preset activation condition is to introduce a mixture of water vapor and carrier gas at a temperature of 850-950℃ for 2-8 hours;

[0027] The second preset activation condition is to introduce a mixture of CO2 and carrier gas at a temperature of 750-850℃ for 1-6 hours.

[0028] The volume ratio of water vapor to carrier gas is 6:4-8:2, and the volume ratio of CO2 to carrier gas is 5:5-7:3.

[0029] Furthermore, the carrier gas is one or more of nitrogen, argon, helium, and reaction tail gas; the apparent velocity of the total gas in the fluidized bed reaction unit is controlled to be 0.01-0.3 m / s, preferably 0.04-0.12 m / s.

[0030] Furthermore, the yield of the porous carbon product is ≥30%, and the specific surface area is ≥1500 m². 2 / g, pore size distribution: microporosity ≥80%, where micropores are pores with a diameter <2nm.

[0031] After each cycle of more than 500 hours, the heat-carrying particles are removed and regenerated in an oxidizing atmosphere at 750±50℃ for 1-2 hours.

[0032] The present invention also provides a porous carbon activation system for the above-mentioned porous carbon activation method based on carrier particle recycling, comprising,

[0033] The raw material heating unit is used to heat the carbon raw material;

[0034] The first heating unit is used to heat the heat-carrying particles;

[0035] Fluidized bed reaction unit, used to provide space for activation reaction;

[0036] A heat-carrying particle conveying unit is disposed between the first heating unit and the fluidized bed reaction unit;

[0037] The unloading and cooling unit is connected to the fluidized bed reaction unit and is used to carry and cool the porous carbon product generated by the reaction.

[0038] An activation gas supply unit is used to supply activation gas to the fluidized bed reaction unit.

[0039] The exhaust gas recirculation unit is used to return the exhaust gas generated by the activation reaction to the activation gas supply unit.

[0040] Compared with existing technologies, this invention has successfully solved three major technical problems in the traditional porous carbon preparation process through the synergistic effect of the heat-carrying particle circulation dynamic heat transfer system, the steam / CO2 cascade activation device and the tail gas energy closed-loop recovery unit: (1) the technical defect of insufficient control precision of reaction temperature field, which significantly reduces the temperature fluctuation range of the activation bed from more than ±50℃ in the traditional process to ±5℃; (2) the energy consumption has been greatly reduced, resulting in a 35%-58% reduction in overall energy consumption; and (3) the precise control of pore structure parameters has been achieved.

[0041] Experimental verification shows that the technical solution of this invention can stably prepare high-performance porous carbon materials with a specific surface area ≥1800m² / g, and exhibits excellent adaptability to various raw materials such as petroleum coke, biochar, and solid waste. In terms of industrial implementation, the technical solution of this invention demonstrates outstanding technical effects: a single set of equipment has a processing capacity of 12-15kg / h, a product yield consistently maintained above 30%, and a continuous stable operating time exceeding 1000 hours. These technical parameters indicate that this invention provides an industrial production solution with significant advantages such as precise temperature control, high energy efficiency, and strong raw material adaptability for high-end applications such as silicon-carbon anodes in lithium-ion batteries. Its comprehensive technical indicators represent an order-of-magnitude improvement over traditional processes, demonstrating outstanding substantive features and significant progress, and possessing significant industrial application value.

[0042] In particular, this invention simultaneously optimizes energy consumption and environmental protection indicators, reducing fresh activation gas consumption by 30-50%, overall energy consumption by 35-45%, and CO2 emissions by over 40%. The pore structure is precisely controlled through step-by-step construction, achieving a microporosity of up to 92% and a mesoporosity that can be flexibly adjusted within the 10-30% range. Overall costs are reduced by over 35%, providing a highly efficient, low-carbon, and controllable upgrade solution for related industries. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the preparation process of the porous carbon activation method based on carrier particle recycling in the embodiment;

[0044] Figure 2 This is a schematic diagram of the porous carbon activation system in the embodiment;

[0045] Figure 3 The image shows the porous carbon prepared in Example 2 on a 5 μm scale using SEM.

[0046] Figure 4 The image shows the porous carbon prepared in Example 2 using a 30 μm scale SEM image.

[0047] Figure 5 The image shows the porous carbon prepared in Example 3 on a 5 μm scale using SEM.

[0048] Figure 6 This is a SEM image of the porous carbon prepared in Example 3 on a 10 μm scale. Detailed Implementation

[0049] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0050] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0051] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0052] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] Please see Figure 1 As shown, Figure 1 This is a schematic diagram of the preparation process of the porous carbon activation method based on carrier particle recycling in the embodiment;

[0054] This invention provides a method for activating porous carbon based on carrier particle recycling, comprising:

[0055] Step S1: Inert gas is used to pneumatically transport the carbon feedstock heated by the feedstock heating unit to the fluidized bed reaction unit.

[0056] Step S2: The heat-carrying particles heated by the first heating unit are continuously and stably fed into the fluidized bed reaction unit;

[0057] Step S3: The activation gas and the carrier gas are introduced into the fluidized bed reaction unit through the activation gas supply unit according to a predetermined mixing ratio, so that the heat-carrying particles and the carbon raw material form a stable fluidized bed.

[0058] Step S4: The porous carbon that has completed the activation reaction under the preset activation conditions is separated from the heat-carrying particles. The porous carbon is transported to the unloading cooling unit by inert gas at a predetermined temperature. The heat-carrying particles are returned to the first heating unit for cyclic heating and reuse through the heat-carrying particle conveying unit.

[0059] Step S5: The activated porous carbon product is discharged to the product discharge cooling unit under inert gas protection at a high temperature of 600±50℃, and cooled to below 50℃ to obtain the porous carbon product.

[0060] The tail gas from the activation reaction is partially returned to the activation gas supply unit via the tail gas recirculation unit, with the proportion of the tail gas being 20-80 vol.

[0061] The activation gas is one or a combination of water vapor and CO2, the preset activation conditions include a preset activation temperature and a preset activation time, and the porous carbon is a product prepared from carbon raw materials that have undergone an activation reaction.

[0062] The fluidized bed reaction unit is heated by either electric heating or natural gas combustion heating, preferably electric heating.

[0063] Specifically, the carbon raw material is one or more of biochar, petroleum coke, phenolic resin, and pitchblende.

[0064] The carbon raw material has a particle size range of 2-10 μm and a specific surface area of ​​≤400 m² / g.

[0065] Specifically, the temperature range for heating the carbon raw material by the raw material heating unit is 300-700℃, and the temperature range for heating the heat-carrying particles by the first heating unit is 900-1000℃.

[0066] Specifically, the carrier particles are one or more of alumina, silicon dioxide, and metal particles;

[0067] The particle size of the heat-carrying particles is ≤300μm.

[0068] Specifically, the heat-carrying particles are spherical particles with a particle size of 80-120 μm.

[0069] Specifically, the mass ratio of heat-carrying particles to carbon feedstock in the fluidized bed reaction unit is less than or equal to 5, preferably in the range of 0.5-2.

[0070] A valve for controlling the heat carrier circulation rate is provided between the first heating unit and the fluidized bed reaction unit.

[0071] Specifically, the preset activation conditions include a first preset activation condition and a second preset activation condition;

[0072] The first preset activation condition is to introduce a mixture of water vapor and carrier gas at a temperature of 850-950℃ for 2-8 hours;

[0073] The second preset activation condition is to introduce a mixture of CO2 and carrier gas at a temperature of 750-850℃ for 1-6 hours.

[0074] The volume ratio of water vapor to carrier gas is 6:4-8:2, and the volume ratio of CO2 to carrier gas is 5:5-7:3.

[0075] Specifically, the carrier gas is one or more of nitrogen, argon, helium, and reaction tail gas; the apparent velocity of the total gas in the fluidized bed reaction unit is controlled at 0.01-0.3 m / s, preferably 0.04-0.12 m / s, and the flow ratio of the activation gas to the carrier gas is 0.05-1.

[0076] Specifically, the yield of the porous carbon product is ≥30%, and the specific surface area is ≥1500 m². 2 / g, pore size distribution: microporosity ≥80%, mesoporosity ≤20%, where micropores are pores with a diameter <2nm and mesopores are pores with a diameter range of 2-50nm.

[0077] After each cycle of 500 hours, the heat-carrying particles are removed and regenerated in an oxidizing atmosphere at 750±50℃ for 1-2 hours.

[0078] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0079] Example 1: Preparation of petroleum coke-based porous carbon

[0080] Detailed steps

[0081] Raw material pretreatment: Petroleum coke with a particle size range of 5-8μm and a specific surface area of ​​350m² / g is used as carbon raw material. It is heated to 650℃ in the raw material heating unit under the protection of carrier gas N2, and then pneumatically conveyed to the fluidized bed reaction unit at a rate of 10kg / h.

[0082] Heat-carrying particle circulation: Spherical alumina particles with a particle size of 100μm are used as heat-carrying particles, heated to 950℃, and the mass ratio of heat-carrying particles to raw materials is controlled at 1.5. The particles are stably input into the fluidized bed reaction unit through a water-cooled high-temperature valve, wherein the valve core temperature is set at 180℃.

[0083] Cascade activation:

[0084] First stage: At a temperature of 900℃, a mixture of water vapor and N2 gas was introduced for activation for 5 hours, with an apparent gas velocity of 0.08 m / s and a volume ratio of water vapor to N2 of 7:3.

[0085] Second stage: Activation with a mixture of CO2 and N2 gas at 850℃ for 4 hours, with a collision frequency of 10-1 between the heat-carrying particles and the raw materials. 4 -10 5 The rate of change is 6 times per second, and the volume ratio of CO2 to N2 introduced is 6:4.

[0086] Product cooling: The unloaded product is cooled to 50°C under N2 protection at a temperature of 600°C through multi-stage heat exchange.

[0087] Exhaust gas recirculation: 70% of the exhaust gas is returned to the activation gas supply unit.

[0088] Test results:

[0089] The specific surface area of ​​the porous carbon product is 2050 m² / g, the microporosity is 88%, and the mesoporosity is 10%; the porous carbon yield is 33%, and the energy consumption per ton of product is 6200 kW·h; the silicon-carbon material with a silicon loading of 50% prepared by it retains 92% of its capacity after 100 cycles.

[0090] Please see Figures 3-4 , Figure 3This is a SEM image of the porous carbon prepared in Example 2 on a 5 μm scale. Figure 4 The image shows the porous carbon prepared in Example 2 on a 30 μm scale using SEM.

[0091] Example 2: Preparation of biochar-based porous carbon

[0092] Raw material pretreatment: Coconut shell charcoal with a particle size range of 3-6μm and a specific surface area of ​​280m² / g is taken as carbon raw material and heated to 450℃ in the raw material heating unit under the protection of carrier gas N2, and then conveyed to the fluidized bed reaction unit by pneumatic conveying at 8kg / h.

[0093] Cascade activation:

[0094] First stage: At a temperature of 880℃, a mixture of water vapor and N2 gas was introduced for activation for 6 hours, with an apparent gas velocity of 0.06 m / s and a volume ratio of water vapor to N2 of 8:2.

[0095] Second stage: At a temperature of 780℃, a mixture of CO2 and Ar gas was introduced for activation for 4 hours, with a volume ratio of CO2 to N2 of 5:5.

[0096] Exhaust gas recirculation: 20% of the exhaust gas is returned to the activation gas supply unit.

[0097] The remaining steps and parameters are the same as in Example 1;

[0098] Test results:

[0099] The specific surface area of ​​the porous carbon product is 1800 m² / g, the microporosity is 85%, and the mesoporosity is 12%; the porous carbon yield is 31%, and the energy consumption per ton of product is 6300 kW·h; the silicon-carbon material prepared with it with a silicon loading of 50% retains 90% of its capacity after 100 cycles.

[0100] Please see Figures 5-6 , Figure 5 This is a SEM image of the porous carbon prepared in Example 3 on a 5 μm scale. Figure 6 This is a SEM image of the porous carbon prepared in Example 3 on a 10 μm scale.

[0101] Example 3: Preparation of Phenolic Resin-Based Porous Carbon

[0102] Raw material pretreatment: Phenolic resin carbon with a particle size range of 2-4μm and a specific surface area of ​​320m² / g is taken as carbon raw material and heated to 700℃ in the raw material heating unit under the protection of carrier gas N2, and then pneumatically conveyed to the fluidized bed reaction unit at 12kg / h.

[0103] Heat-carrying particle circulation: Silica particles with a particle size of 120μm are used as heat-carrying particles, heated to 1000℃, and the mass ratio of heat-carrying particles to raw materials is controlled at 2.

[0104] Cascade activation:

[0105] First stage: At a temperature of 950℃, a mixture of water vapor and N2 gas was introduced for activation for 8 hours, with an apparent gas velocity of 0.12 m / s and a volume ratio of water vapor to N2 of 7:3.

[0106] Second stage: At a temperature of 850℃, a mixture of CO2 and N2 gas was introduced for activation for 6 hours, with a volume ratio of CO2 to N2 of 7:3.

[0107] Exhaust gas recirculation: 80% of the exhaust gas is returned to the activation gas supply unit.

[0108] The remaining steps and parameters are the same as in Example 1;

[0109] Test results:

[0110] The specific surface area of ​​the porous carbon product is 2100 m² / g, the microporosity is 90%, and the mesoporosity is 8%; the porous carbon yield is 34%, and the energy consumption per ton of product is 6100 kW·h; the silicon-carbon material prepared with it has a silicon loading of 50% retains 93% after 100 cycles.

[0111] Example 4: Pitch-based carbon-based hierarchical porous carbon

[0112] Raw material pretreatment: Pitch peat with a particle size range of 8-10μm and a specific surface area of ​​220m² / g is taken as carbon raw material and heated to 600℃ in the raw material heating unit under the protection of carrier gas N2, and then conveyed to the fluidized bed reaction unit by pneumatic conveying at 15kg / h.

[0113] Heat-carrying particle circulation: Surface SiO2 spherical particles with an average particle size of 90μm are used as heat-carrying particles, heated to 980℃, and the mass ratio of heat-carrying particles to raw materials is controlled at 1.8.

[0114] Cascade activation:

[0115] First stage: At a temperature of 920℃, a mixture of water vapor and N2 gas was introduced for activation for 7 hours, with an apparent gas velocity of 0.1 m / s and a volume ratio of water vapor to N2 of 6:4.

[0116] Second stage: At a temperature of 820℃, a mixture of CO2 and Ar gas was introduced for activation for 3 hours. The volume ratio of CO2 to Ar introduced was 7:3, and the apparent gas velocity was 0.07m / s.

[0117] The remaining steps and parameters are the same as in Example 1;

[0118] Test results:

[0119] The porous carbon product produced has a specific surface area of ​​1900 m² / g, a microporosity of 82%, and a mesoporosity of 17%; the porous carbon yield is 32%, and the continuous operation cycle of the device reaches 1100 hours; the silicon-carbon material with a silicon loading of 50% prepared by it has a capacity retention rate of 89% after 100 cycles.

[0120] Example 5: Bituminous coal-based charcoal

[0121] Raw material pretreatment: Bituminous coal-based carbon with a particle size range of 6-9μm and a specific surface area of ​​380m² / g is taken as carbon raw material and heated to 550℃ in the raw material heating unit under the protection of carrier gas N2, and then pneumatically conveyed to the fluidized bed reaction unit at 11kg / h.

[0122] Heat-carrying particle circulation: Spherical alumina particles with a particle size of 150μm are used as heat-carrying particles, heated to 930℃, and the mass ratio of heat-carrying particles to raw materials is controlled at 0.8. The particles are stably fed into the fluidized bed reaction unit through a water-cooled high-temperature valve.

[0123] Cascade activation:

[0124] First stage: At a temperature of 850℃, a mixture of water vapor and N2 gas is introduced for activation for 3 hours, with a volume ratio of water vapor to N2 of 5:5.

[0125] Second stage: No gas is introduced, and the heat is maintained for 1 hour by the residual heat of the heat-carrying particles;

[0126] The remaining steps and parameters are the same as in Example 1;

[0127] Test results: The pore size is concentrated in 4-6nm (accounting for 88%), the tap density is 0.68g / cm³, and the energy consumption of the device is reduced by 20%.

[0128] Example 6: Composite carbon source porous carbon

[0129] Raw material pretreatment: A mixture of petroleum coke and phenolic resin with a particle size of 5μm was taken as the carbon raw material and heated to 680℃ in the raw material heating unit under the protection of carrier gas N2. It was then pneumatically conveyed to the fluidized bed reaction unit at a rate of 13kg / h. The ratio of the mixed raw materials was petroleum coke: phenolic resin = 3:2.

[0130] Heat transfer particle circulation: Spherical Al2O3 and spherical SiO2 with a particle size of 110μm are mixed in a mass ratio of 1:1h as heat transfer particles, and the mass ratio of heat transfer particles to raw materials is controlled at 1.3.

[0131] Cascade activation:

[0132] First stage: Activate the gas mixture of water vapor and CO2 for 6 hours at a temperature of 930℃.

[0133] Second stage: Purge with N2 for 2 hours at a temperature of 800℃.

[0134] The remaining steps and parameters are the same as in Example 1;

[0135] Test results:

[0136] The specific surface area of ​​the porous carbon product is 2200m² / g, the comprehensive energy consumption is 6200kW·h / ton, the mixed carbon source increases the pore volume to 1.5cm³ / g, and the silicon loading exceeds 55%.

[0137] The following are examples of conventional processes implemented in contrast to the method of this invention. By comparing key parameters and performance indicators, the technical advantages of this invention are highlighted.

[0138] Comparative Example 1: Traditional single-heat-source fluidized bed activation process (without heat-carrying particle circulation)

[0139] Process steps

[0140] Raw material pretreatment: 5-8μm petroleum coke (specific surface area 350m² / g) is used as carbon raw material and heated to 650℃ in the raw material heating unit under N2 protection. It is then pneumatically conveyed to a Φ800mm conventional fluidized bed (without heat-carrying particle circulation system) at a rate of 10kg / h.

[0141] Activation reaction: The fluidized bed reaction unit is electrically heated at the bottom and a mixture of steam and nitrogen (volume ratio 7:3) is introduced. The mixture is activated at a constant temperature of 900℃ for 9 hours, with an apparent gas velocity of 0.08 m / s.

[0142] Product processing: After activation, the porous carbon is directly unloaded and cooled, and the exhaust gas is directly discharged.

[0143] Test results

[0144] Temperature field: Axial temperature difference of bed layer ±65℃, radial temperature difference ±40℃;

[0145] Product performance: Specific surface area 1880±180m² / g, microporosity 68%, capacity retention 75% after 100 cycles with silicon loading of 70%;

[0146] Energy consumption and efficiency: The overall energy consumption is 6800 kWh / ton, the product yield is 22%, and the continuous operating cycle is 300 hours.

[0147] Differences from the present invention

[0148] Core defects: The lack of dynamic heat transfer through heat-carrying particles and reliance on static wall heating leads to uneven temperature distribution, and micropore ablation and insufficient activation coexist.

[0149] Performance gap: The fluctuation range of specific surface area is 3.6 times that of this invention, resulting in higher energy consumption and lower yield.

[0150] Comparative Example 2: Fixed gas ratio activation process (without step-by-step control)

[0151] Process steps

[0152] Raw material pretreatment: Take 3-6μm coconut shell charcoal (specific surface area 280m² / g) as carbon raw material, preheat it to 450℃ under Ar protection, and then convey it to the fluidized bed by pneumatic conveying at 8kg / h.

[0153] Heat-carrying particle circulation: Alumina particles with a carbon layer on the surface of 80μm are used as heat-carrying particles and heated to 920℃. The mass ratio of heat-carrying particles to raw materials is 1.2.

[0154] Activation reaction: A mixture of water vapor / CO2 / Ar gas (volume ratio 5:3:2) was introduced throughout the process, and activation was carried out at 850℃ for 11 hours without stage switching.

[0155] Exhaust gas recirculation: 50% of the exhaust gas is returned to the activation gas supply unit (consistent with the average value of this invention).

[0156] Test results

[0157] Pore ​​structure: microporosity 62%, mesoporosity 28%, pore size distribution dispersion ±25%;

[0158] Test results: Product specific surface area 1450m² / g, silicon load cycle retention rate 80%, tap density 0.52g / cm³;

[0159] Energy consumption and efficiency: Overall energy consumption is 7200 kWh / ton, and the yield is 25%.

[0160] Differences from the present invention

[0161] Core defect: The fixed gas ratio leads to water vapor and CO2 competing for the reaction, resulting in insufficient micropore formation and excessive mesopore expansion;

[0162] Performance gap: The microporosity is 27% lower and the specific surface area is 19% lower, which cannot meet the high microporosity requirement of silicon-carbon anodes.

[0163] Comparative Example 3: Traditional process without exhaust gas recirculation (energy not closed loop)

[0164] Process steps

[0165] Raw material pretreatment: Take 2-4μm phenolic resin carbon (specific surface area 320m² / g) as carbon raw material, preheat it to 700℃ under N2 protection, and convey it to the fluidized bed by pneumatic conveying at 12kg / h.

[0166] Heat transfer particle circulation: 120μm spherical silica particles are used as heat transfer particles and heated to 1000℃. The mass ratio of heat transfer particles to raw materials is 2.0.

[0167] Activation reaction: Activation is carried out in two stages (same as in Example 3 of this invention), but the exhaust gas is directly discharged, and only the waste heat from product cooling is recovered (accounting for about 10% of the total energy consumption).

[0168] Test results

[0169] Energy efficiency: Fresh activation gas consumption is 180 m³ / h, comprehensive energy consumption is 7500 kW·h / ton, and CO2 emissions are 1.5 tons / ton of product;

[0170] Equipment operation: Continuous operation cycle of 400 hours; high-temperature valves require frequent maintenance due to thermal stress loss.

[0171] Product performance: Specific surface area 2000m² / g (similar to the present invention), but energy consumption and environmental protection indicators are significantly degraded.

[0172] Differences from the present invention

[0173] Core defects: Failure to establish a closed-loop energy system for exhaust gas, resulting in doubled fresh gas consumption and carbon emissions, and poor equipment thermal stability;

[0174] Performance gap: Energy consumption is 77% higher, continuous operation cycle is 60% shorter, which does not meet the requirements of green manufacturing.

[0175] Please refer to Table 1 - Comparison Table of Porous Carbon Preparation for overall experimental differences.

[0176] Table 1 - Comparison Table of Porous Carbon Preparation

[0177]

[0178] This invention successfully solves three major technical problems in the traditional porous carbon preparation process through the synergistic effect of the heat-carrying particle circulation dynamic heat transfer system, the steam / CO2 cascade activation device and the tail gas energy closed-loop recovery unit: (1) the technical defect of insufficient control precision of reaction temperature field, which significantly reduces the temperature fluctuation range of the activation bed from more than ±50℃ in the traditional process to ±5℃; (2) the energy consumption is greatly reduced, and the overall energy consumption is reduced by 35%-58%; (3) the precise control of pore structure parameters is realized.

[0179] Experimental verification shows that the technical solution of this invention can stably prepare high-performance porous carbon materials with a specific surface area ≥1800m² / g, and exhibits excellent adaptability to various raw materials such as petroleum coke, biochar, and solid waste. In terms of industrial implementation, the technical solution of this invention demonstrates outstanding technical effects: a single set of equipment has a processing capacity of 12-15kg / h, a product yield consistently maintained above 30%, and a continuous stable operating time exceeding 1000 hours. These technical parameters indicate that this invention provides an industrial production solution with significant advantages such as precise temperature control, high energy efficiency, and strong raw material adaptability for high-end applications such as silicon-carbon anodes in lithium-ion batteries. Its comprehensive technical indicators represent an order-of-magnitude improvement over traditional processes, demonstrating outstanding substantive features and significant progress, and possessing significant industrial application value.

[0180] Please see Figure 2 As shown, Figure 2 As shown in the schematic diagram of the porous carbon activation system in the embodiment, the present invention also provides a porous carbon activation system applied to the above-mentioned porous carbon activation method based on carrier particle circulation, comprising,

[0181] The raw material heating unit is used to heat the carbon raw material;

[0182] The first heating unit is used to heat the heat-carrying particles;

[0183] Fluidized bed reaction unit, used to provide space for activation reaction;

[0184] A heat-carrying particle conveying unit is disposed between the first heating unit and the fluidized bed reaction unit;

[0185] The unloading and cooling unit is connected to the fluidized bed reaction unit and is used to carry and cool the porous carbon product generated by the reaction.

[0186] An activation gas supply unit is used to supply activation gas to the fluidized bed reaction unit.

[0187] The exhaust gas recirculation unit is used to return the exhaust gas generated by the activation reaction to the activation gas supply unit.

[0188] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A porous carbon activation method based on carrier particle circulation, characterized by, comprising, inert gas force-conveying carbon raw material heated by raw material heating unit to fluidized bed reaction unit; continuously and stably inputting heat carrier particles heated by first heating unit to fluidized bed reaction unit; introducing activation gas and carrier gas into fluidized bed reaction unit through activation gas supply unit at predetermined mixing ratio to form stable fluidized bed layer of heat carrier particles and carbon raw material; separating activated carbon prepared under preset activation condition from heat carrier particles, force-conveying activated carbon to discharge cooling unit through inert gas at predetermined temperature, and returning heat carrier particles to first heating unit through heat carrier particle conveying unit for recycling and use; wherein, the activation gas is one or combination of water vapor and CO2, the preset activation condition includes preset activation temperature and preset activation time, and the activated carbon is product prepared from carbon raw material after activation reaction; after the use time of heat carrier particles reaches preset recycling time, the heat carrier particles are discharged for regeneration treatment in oxidizing atmosphere; reaction tail gas of activation reaction is partially returned to activation gas supply unit through tail gas recycling unit, and the carrier gas is one or several of nitrogen, argon, helium and reaction tail gas.

2. The carrier particle recycling-based activated carbon activation method according to claim 1, wherein, the carbon raw material is one or several of biomass carbon, petroleum coke, phenolic resin and pitch carbon; the particle size of carbon raw material is 2-10 μm, and the specific surface area is ≤400 m² / g.

3. The carrier particle circulation-based porous carbon activation method according to claim 1, characterized by, the temperature range of raw material heating unit for heating carbon raw material is 300-700 ℃, and the temperature range of first heating unit for heating heat carrier particles is 900-1000 ℃.

4. The carrier particle recycling-based activated carbon activation method according to claim 1, wherein, the carrier particle is one or several of alumina, silica, zirconia and silicon carbide; the particle size of heat carrier particles is ≤300 μm.

5. The porous carbon activation method based on carrier particle circulation according to claim 4, characterized by, the heat carrier particles are spherical particles with particle size of 80-120 μm.

6. The carrier particle circulation-based porous carbon activation method according to claim 1, wherein the mass ratio of heat carrier particles to carbon raw material in fluidized bed reaction unit is less than or equal to 5.

7. The carrier particle circulation-based porous carbon activation method according to claim 1, characterized by, the preset activation condition includes first preset activation condition and second preset activation condition; the first preset activation condition is introducing mixed gas of water vapor and carrier gas at 850-950 ℃ for 2-8 hours; the second preset activation condition is introducing mixed gas of CO2 and carrier gas at 750-850 ℃ for 1-6 hours; wherein, the volume ratio of water vapor to carrier gas is 6:4-8:2, and the volume ratio of CO2 to carrier gas is 5:5-7:

3.

8. The support particle circulation-based porous carbon activation method according to claim 1, characterized by, the superficial velocity of total gas in fluidized bed reaction unit is controlled to be 0.01-0.3 m / s.

9. The support particle circulation-based porous carbon activation method according to claim 1, characterized by, The yield of the porous carbon product is ≥ 30%, the specific surface area is ≥ 1500 m 2 / g, and the pore size distribution is: microporosity ≥ 80%, mesoporosity ≤ 20%.

Images