Preparation method of porous carbon and silicon carbon material based on carbon source pyrolysis
By using organic chemical raw materials such as ethylene tar and terephthalic acid crosslinking agent in a continuous pyrolysis-rapid activation process, the high cost and environmental pollution problems in the preparation of porous carbon materials have been solved, realizing the preparation of porous carbon and silicon carbon materials with high efficiency and low consumption, and improving material performance and cycle life.
Patent Information
- Application Number
- CN202511841132.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-01-23
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing porous carbon material preparation technologies rely on high-cost carbon sources, leading to resource waste and environmental pollution. Furthermore, the preparation processes are complex and energy-intensive, limiting the large-scale production and performance iteration of the materials.
Porous carbon is prepared by using organic chemical raw materials such as ethylene tar, coal tar, and anthracene oil, and crosslinking agents such as terephthalic acid, through a continuous pyrolysis-rapid quenching activation process. Carbon dioxide, water vapor, and purified carbon black tail gas are used as activators, integrating the traditional step-by-step process to reduce costs and improve efficiency.
This technology enables the efficient and low-consumption preparation of porous carbon materials, reducing raw material costs, minimizing environmental pollution, enhancing pore structure control and material performance, and making them suitable for lithium-ion battery anodes, thus extending cycle life.
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Figure CN121377012A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of carbon-based functional material preparation, and particularly relates to a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis. BACKGROUND
[0002] In the field of carbon-based functional materials, porous carbon has become a key carrier for promoting the technological innovation of energy storage and environmental governance due to its unique physical and chemical characteristics, including a specific surface area of 1600 m 2 / g or more, precisely controllable microporous / mesoporous hierarchical pore structure, and excellent thermal / chemical stability. Its high specific surface area provides abundant active sites for molecular-level adsorption, and the adjustable pore structure can be customized for specific application scenarios, thereby achieving efficient CO2 capture, VOCs purification, and water treatment in the field of adsorption and separation. As a nanomaterial carrier, it can uniformly disperse silicon, platinum, and other nanoparticles, enhancing the activity and durability of the material, and is widely used in energy storage materials and environmental catalytic reactions.
[0003] Particularly noteworthy is the silicon-carbon composite material prepared based on porous carbon, which successfully overcomes the pulverization failure problem of silicon-based anodes in lithium-ion batteries due to volume expansion by precisely filling nano-silicon particles (0.4-5 nm) into the pore channels of porous carbon. This structure not only gives the material a uniform nanoscale distribution, but also achieves a breakthrough in lithium storage capacity, with experimental values generally exceeding 1800 mAh / g. Moreover, due to the buffering effect and optimized conductive network of the carbon matrix, the cycle life is significantly extended to more than 800 times. Therefore, silicon-carbon anodes have become a core research direction for lithium-ion batteries with an energy density >300 Wh / kg, and have strategic significance for the industrialization of electric vehicles and large-scale energy storage systems.
[0004] However, the current preparation technology of porous carbon materials still faces severe common bottlenecks. The industry excessively relies on high-cost carbon sources such as phenolic resin and refined pitch, which are not only costly, but also release a large amount of toxic by-products such as benzene and aldehyde during pyrolysis and carbonization, producing tar-like residues that not only clog equipment but also need to be disposed as hazardous waste. Meanwhile, the carbonization and activation process is complex, with a single equipment capacity of less than 200 kg, high energy consumption, and large emissions, resulting in an overall yield of less than 23% from carbon source to porous carbon, with extremely high costs. This not only wastes resources but also exacerbates environmental pollution risks, severely restricting the large-scale production and performance iteration of the material. Under this background, it is urgent to develop an innovative preparation scheme that integrates resource recycling and high efficiency and low consumption. SUMMARY
[0005] The present application aims to provide a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, which solves the technical problems raised in the background art.
[0006] To achieve the above object, the present application provides the following technical solutions: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, comprising the following steps:
[0007] S1, carbon source pyrolysis carbonization process: selecting ethylene tar, coal tar, anthracene oil, and oil sludge package as carbonaceous raw materials, and selecting p-xylene glycol, benzaldehyde and its related derivatives as cross-linking agents, the carbonaceous raw materials or the composite precursor generated by the reaction thereof after mixing and pretreatment are transported to a special reaction furnace containing a pyrolysis section and a quenching section, wherein the pyrolysis section and the quenching section are directly connected through a flow guide pipeline, and the inner diameter of the pipeline is 1 / 3-1 / 2 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 400-1800℃ for 1-4h;
[0008] S2, continuous activation process: the primary carbonates directly enter the quenching section, and the quenching rate is controlled to be 50-200℃ / min; carbon dioxide, water vapor, and purified carbon black tail gas or a mixture thereof are introduced into the quenching section as an activating agent during the quenching process, and the quenching gradient is synchronized with the temperature drop at 800-1500℃, and the activation reaction is completed at 600-1000℃ for 0.5-8h to obtain activated porous carbon;
[0009] S3, silicon loading process: the activated porous carbon is crushed, graded, and impurity-removed, and is placed in a rotary furnace and a fluidized bed chemical vapor deposition device, and 30%-250% of the mass of the activated porous carbon is introduced into silane gas, and is reacted at 420-600℃ for 1-24h, and then 1%-20% of the mass of the activated porous carbon is introduced into single or mixed carbon source gas such as methane, acetylene, propylene, and butene, and is reacted at 500-750℃ for 1-24h to obtain a silicon-carbon material.
[0010] Preferably, the carbonaceous raw material is selected from at least one of ethylene tar, coal tar, anthracene oil, and oil sludge package.
[0011] Preferably, the cross-linking agent is selected from at least one of p-xylene glycol, dimethyl terephthalate, dioctyl terephthalate, 2-nitro-p-xylene glycol, p-xylene glycol diacetate, 4-hydroxymethyl benzyl alcohol, p-xylylformaldehyde, benzaldehyde, benzoic acid, benzyl alcohol, cinnamyl aldehyde, m-nitrobenzaldehyde, o-nitrobenzaldehyde, p-nitrobenzaldehyde, phenylacetaldehyde, benzyl cyanide, benzoin, and o-hydroxybenzaldehyde, and especially p-xylylformaldehyde and benzaldehyde derivatives containing hydroxyl groups are preferred.
[0012] Preferably, in step S2, the activating agent is selected from one of carbon dioxide, water vapor, or purified carbon black tail gas; and the mass ratio of the activating agent to the primary carbonates is 0.2:1-5:1; and the temperature rising and falling rate of the activation reaction is the natural temperature field gradient from the pyrolysis section to the quenching section.
[0013] Preferably, the "purified carbon black tail gas" of step S2 is specifically: the production of carbon black tail gas removes floating powder non-gas impurities by filtration, removes nitrogen-containing and sulfur-containing gas impurities by gas filtration, and the obtained purified carbon black tail gas is an activation gas containing a certain proportion of carbon dioxide and water vapor.
[0014] Preferably, the pyrolysis section of the special reaction furnace is controlled at a pressure of 0.1-0.3MPa, and the quenching section is controlled at a pressure of 0.05-0.1MPa, to ensure stable gas flow and prevent product agglomeration.
[0015] A kind of porous carbon and silicon-carbon material based on carbon source pyrolysis, the specific surface area of porous carbon is 800-2500m 2 / g, and micropore accounts for 40%-100%, mesopore accounts for 0%-60%, total pore volume is 0.4-1.8cm 3 / g;The particle size of nanosilicon in silicon-carbon material is 0.7-5nm, the reversible specific capacity is 800-2600mAh / g, the first charge-discharge coulombic efficiency is >92%, and the capacity retention rate is ≥80% after 1000 charge-discharge cycles.
[0016] Compared with the related art, the preparation method of the porous carbon and silicon-carbon material based on carbon source pyrolysis provided by the present application has the following beneficial effects:
[0017] 1. The preparation method of the porous carbon and silicon-carbon material based on carbon source pyrolysis provided by the present application selects ethylene tar, coal tar, anthracene oil, oil sludge package and other organic chemical raw materials and chemical carbon-containing by-products as carbonaceous raw materials, selects p-xylyl alcohol, benzaldehyde and related derivatives thereof as crosslinking agents, and can also use carbon black fine powder waste and other industrial solid wastes, thereby avoiding the dependence on single high-purity carbon source, reducing the raw material cost, realizing the high-value recycling of industrial solid wastes, and reducing resource waste.
[0018] 2. The preparation method of the porous carbon and silicon-carbon material based on carbon source pyrolysis provided by the present application integrates the traditional "pyrolysis-cooling-activation" process of porous carbon into a continuous "pyrolysis-quenching activation" process by using a special reaction furnace with a pyrolysis section, a quenching section and a specific guide pipe directly connected, thereby reducing energy consumption redundancy and improving preparation efficiency. In the activation process, carbon dioxide, water vapor and purified carbon black tail gas are used as activation agents, wherein the purified carbon black tail gas is a gas containing a certain proportion of carbon dioxide and water vapor after impurity removal, which realizes the resource utilization of the tail gas, reduces pollution caused by direct emission, avoids the strong corrosive problem of some traditional activation agents, and enhances the environmental friendliness of the process.
[0019] 3, The application provides a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, by controlling the pressure of the pyrolysis section and the quenching section, the proportion of the activating agent, the activation temperature and time and other key process parameters, so that the specific surface area of the porous carbon reaches 800-2500m 2 / g, the micropore ratio is 40%-96%, the mesopore ratio is 4%-60%, the total pore volume is 0.4-1.8cm 3 / g, the pore structure is reasonably regulated, and the mass transfer and storage capacity are improved. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 is a flow chart of the application;
[0021] Figure 2 is an extended flow chart of the carbon source pyrolysis carbonization process of the application;
[0022] Figure 3 is an extended flow chart of the continuous activation process of the application;
[0023] Figure 4 is an extended flow chart of the silicon loading process of the application;
[0024] Figure 5 is an electron scanning microscope photo of the porous carbon prepared by the application;
[0025] Figure 6 is an electron scanning microscope photo of the silicon-carbon material prepared by the application;
[0026] Figure 7 is a first charge-discharge curve diagram of the silicon-carbon material for lithium ion batteries of the application;
[0027] Figure 8 is a performance table of the porous carbon obtained under different process conditions of the application. DETAILED DESCRIPTION
[0028] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.
[0029] Embodiment one:
[0030] Please refer to Figures 1-8 The application provides a technical solution: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, comprising the following steps:
[0031] In the carbon source pyrolysis carbonization process, ethylene tar is selected as the carbonaceous raw material, benzaldehyde is selected as the crosslinking agent, and the carbon source is transported to the special reaction furnace after being uniformly stirred. The pyrolysis section and the quenching section are connected through a guide pipe, and the inner diameter of the pipe is 1 / 2 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 900 DEG C for 2h.
[0032] In the continuous activation process, the primary carbonates directly enter the quenching section, and the quenching rate is controlled at 100 DEG C / min. Water vapor is selected as the activator, and the mass ratio of the water vapor to the primary carbonates is 0.4:1. The quenching gradient is reduced synchronously at 900 DEG C, the pressure of the quenching section is controlled at 0.08 MPa, and the activation reaction is completed at 800 DEG C for 4h to obtain activated porous carbon. The specific surface area of the activated porous carbon is 1700 m 2 / g, the micropore ratio is 90%, the mesopore ratio is 10%, the total pore volume is 0.85 cm 3 / g, and the average pore size is 1.72 nm. The yield of the porous carbon is 18.2%.
[0033] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50 = 8 microns, then subjected to classification and impurity removal treatment, and then placed in a fluidized bed chemical vapor deposition device. First, 100% of the activated porous carbon is introduced into the silane gas, and the reaction is carried out at 500 DEG C for 10h. Then, 10% of the activated porous carbon is introduced into the acetylene gas, and the reaction is carried out at 600 DEG C for 12h. In the finally obtained silicon-carbon material, the particle size of the nano-silicon is 1.72 nm, the reversible specific capacity is 1790 mAh / g, the first charge-discharge coulombic efficiency is 92%, and the capacity retention rate after 1000 charge-discharge cycles is 85%. All performance indicators are excellent.
[0034] Example two:
[0035] Please refer to Figures 1-8 The present application provides a technical solution: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, comprising the following steps:
[0036] In the carbon source pyrolysis carbonization process, ethylene tar is selected as the carbonaceous raw material, benzaldehyde is selected as the crosslinking agent, and the mass ratio is 97.5:2.5. After being pretreated by stirring and mixing, it is transported to the special reaction furnace. The pyrolysis section and the quenching section are directly connected through a guide pipe, and the inner diameter of the pipe is 1 / 2 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 900 DEG C for 2h.
[0037] In the continuous activation process, the primary carbide directly enters the quenching section, and the quenching rate is controlled at 150℃ / min. Carbon black tail gas is selected as the activating agent, and the mass ratio of the carbon black tail gas to the primary carbide is 0.8:1. The quenching gradient is synchronously reduced at 900℃, the pressure of the quenching section is controlled at 0.08MPa, and the activation reaction is completed by keeping the temperature at 800℃ for 3h. The obtained activated porous carbon is detected to have a specific surface area of 1660m 2 / g, micropores account for 85%, mesopores account for 15%, the total pore volume is 0.85cm 3 / g, and the average pore size is 1.83nm. The yield of the porous carbon is 19.6%.
[0038] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50=8 microns, and then is subjected to classification and impurity removal treatment, and then is placed in a fluidized bed chemical vapor deposition device. First, 100% of the activated porous carbon is introduced into silane gas, and is reacted at 500℃ for 10h. Then, 10% of the activated porous carbon is introduced into acetylene gas, and is reacted at 600℃ for 12h. In the finally obtained silicon-carbon material, the particle size of the nano-silicon is 1.83nm, the reversible specific capacity is 1850mAh / g, and the first charge-discharge coulombic efficiency is 92.5%, and all performance indicators are excellent.
[0039] Example Three
[0040] Referring to Figures 1-8 The present application provides a technical solution: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, comprising the following steps:
[0041] In the carbon source pyrolysis carbonization process, ethylene tar and coal tar are selected as carbonaceous raw materials, and the mass ratio is 1:1. Benzaldehyde is selected as a crosslinking agent, and the mass ratio of the carbonaceous raw material to the crosslinking agent is 95:5. After pretreatment by stirring and mixing, the mixture is delivered to a special reaction furnace. The pyrolysis section and the quenching section are directly connected through a flow guide pipe, and the inner diameter of the pipe is 1 / 3 of the diameter of the reaction furnace. Inert protective atmosphere is introduced into the pyrolysis section, and the primary carbide is generated by keeping the temperature at 800℃ for 2h.
[0042] In the continuous activation process, the primary carbide directly enters the quenching section, and the quenching rate is controlled at 100℃ / min. Carbon black tail gas is selected as the activating agent, and the mass ratio of the carbon black tail gas to the primary carbide is 0.8:1. The quenching gradient is synchronously reduced at 800℃, the pressure of the quenching section is controlled at 0.08MPa, and the activation reaction is completed by keeping the temperature at 650℃ for 4h. The obtained activated porous carbon is detected to have a specific surface area of 2050m 2 / g, micropores account for 81%, mesopores account for 19%, the total pore volume is 0.85cm 3 / g, and the average pore size is 1.97nm. The yield of the porous carbon is 20.1%.
[0043] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50 = 8 microns, then treated by classification and impurity removal, and then placed in a fluidized bed chemical vapor deposition device. First, 110% of the mass of the activated porous carbon is passed into silane gas, reacted at 470°C for 16h, and then 10% of the mass of the activated porous carbon is passed into acetylene gas, reacted at 600°C for 12h. In the final obtained silicon-carbon material, the particle size of nano-silicon is 1.97nm, the reversible specific capacity is 1990mAh / g, and the first charge-discharge coulombic efficiency is 93.4%, all performance indicators are excellent.
[0044] Example Four:
[0045] Please refer to Figures 1-8 The present application provides a technical solution: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, comprising the following steps:
[0046] In the carbon source pyrolysis carbonization process, ethylene tar and coal tar are selected as carbonaceous raw materials with a mass ratio of 1:1, and 4-hydroxymethyl benzyl alcohol is selected as a crosslinking agent, and the mass ratio of carbonaceous raw materials to crosslinking agent is 94:6. After pretreatment by stirring and mixing, it is transported to a special reaction furnace, wherein the pyrolysis section and the quenching section are directly connected by a flow guide pipe with an inner diameter of 1 / 3 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 800°C for 2h.
[0047] In the continuous activation process, the primary carbonates directly enter the quenching section, and the quenching rate is controlled at 100℃ / min. Carbon black tail gas is selected as an activator, and the mass ratio of the activator to the primary carbonates is 0.6:1. The quenching gradient is reduced synchronously at 950℃, the pressure of the quenching section is controlled at 0.08MPa, and the activation reaction is completed at 850℃ for 4h. The obtained activated porous carbon has a specific surface area of 1950m 2 / g, micropore ratio of 86%, mesopore ratio of 14%, total pore volume of 0.85cm 3 / g, average pore size of 1.84nm, and porous carbon yield of 23.7%.
[0048] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50 = 8 microns, then treated by classification and impurity removal, and then placed in a fluidized bed chemical vapor deposition device. First, 110% of the mass of the activated porous carbon is passed into silane gas, reacted at 470°C for 16h, and then 10% of the mass of the activated porous carbon is passed into acetylene gas, reacted at 600°C for 12h. In the final obtained silicon-carbon material, the particle size of nano-silicon is 1.97nm, the reversible specific capacity is 1990mAh / g, and the first charge-discharge coulombic efficiency is 93.4%, all performance indicators are excellent.
[0049] Example Five:
[0050] Referring to Figures 1-8 The application provides a technical scheme: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, including the following steps:
[0051] In the carbon source pyrolysis carbonization process, ethylene tar and anthracene oil are selected as carbonaceous raw materials, with a mass ratio of 4:1, and 4-hydroxymethyl benzyl alcohol is selected as a crosslinking agent, and the mass ratio of the carbonaceous raw materials to the crosslinking agent is 94:6; after pretreatment by stirring and mixing, the mixture is transported to a special reaction furnace, wherein the pyrolysis section and the quenching section are directly connected through a flow guide pipeline, and the inner diameter of the pipeline is 1 / 2 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and a primary carbide is generated at 700 DEG C for 2h.
[0052] In the continuous activation process, the primary carbide directly enters the quenching section, and the quenching rate is controlled at 100 DEG C / min. Carbon black tail gas is selected as an activator, and the mass ratio of the carbon black tail gas to the primary carbide is 0.6:1; the temperature is lowered synchronously with the quenching gradient at 950 DEG C, the pressure in the quenching section is controlled at 0.08 MPa, and the activation reaction is completed at 850 DEG C for 4h; the obtained activated porous carbon is detected, and the specific surface area is 1800 m 2 / g, the micropore ratio is 89%, the mesopore ratio is 11%, the total pore volume is 0.85 cm 3 / g, and the average pore size is 1.74 nm; the yield of the porous carbon is 21.3%.
[0053] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50=8 microns, and then subjected to grading and impurity removal treatment, and then placed in a fluidized bed chemical vapor deposition device. First, 105% of the mass of the activated porous carbon is introduced into silane gas, and reacted at 470 DEG C for 16h; then, 10% of the mass of the activated porous carbon is introduced into acetylene gas, and reacted at 600 DEG C for 12h. In the finally obtained silicon-carbon material, the particle size of the nano-silicon is 1.74 nm, the reversible specific capacity is 1800 mAh / g, the first charge-discharge coulombic efficiency is 92%, and all performance indicators are excellent.
[0054] Example six:
[0055] Referring to Figures 1-8 The application provides a technical scheme: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, including the following steps:
[0056] In the carbon source pyrolysis carbonization process, ethylene tar and oil sludge package are selected as carbonaceous raw materials with a mass ratio of 1:3, 4-hydroxymethyl benzyl alcohol is selected as a crosslinking agent, the mass ratio of carbonaceous raw materials to the crosslinking agent is 94:6, after pretreatment by stirring and mixing, the mixture is transported to a special reaction furnace, the pyrolysis section and the quenching section are directly connected through a guide pipeline, and the inner diameter of the pipeline is 1 / 3 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 800 DEG C for 2h.
[0057] In the continuous activation process, the primary carbonates directly enter the quenching section, and the quenching rate is controlled at 100 DEG C / min. Carbon black tail gas is selected as an activator, and the mass ratio of the activator to the primary carbonates is 0.6:1, and the quenching gradient is reduced synchronously at 950 DEG C, the pressure of the quenching section is controlled at 0.08 MPa, and the activation reaction is completed at 850 DEG C for 4h, and the obtained activated porous carbon is detected, and the specific surface area is 1750 m 2 / g, the micropore ratio is 93%, the mesopore ratio is 7%, the total pore volume is 0.85 cm 3 / g, and the average pore size is 1.72 nm, and the yield of the porous carbon is 19.7%.
[0058] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50=8 microns, then treated by grading and impurity removal, and then placed in a fluidized bed chemical vapor deposition device. First, 100% of the activated porous carbon is introduced into the silane gas, and the reaction is carried out at 510 DEG C for 10h, and then 10% of the activated porous carbon is introduced into the acetylene gas, and the reaction is carried out at 600 DEG C for 12h. In the finally obtained silicon-carbon material, the particle size of nano-silicon is 1.72 nm, the reversible specific capacity is 1800 mAh / g, the first charge-discharge coulombic efficiency is 92.5%, and all performance indicators are excellent.
[0059] Example Seven:
[0060] Please refer to Figures 1-8 The present application provides a technical solution: a porous carbon and silicon-carbon material preparation method based on carbon source pyrolysis, comprising the following steps:
[0061] In the carbon source pyrolysis carbonization process, ethylene tar and oil sludge package are selected as carbonaceous raw materials with a mass ratio of 1:3, 4-hydroxymethyl benzyl alcohol is selected as a crosslinking agent, the mass ratio of carbonaceous raw materials to the crosslinking agent is 94:6, after pretreatment by stirring and mixing, the mixture is transported to a special reaction furnace, the pyrolysis section and the quenching section are directly connected through a guide pipeline, and the inner diameter of the pipeline is 1 / 3 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 800 DEG C for 2h.
[0062] In the continuous activation process, the primary carbide directly enters the quenching section, and the quenching rate is controlled at 100℃ / min. Carbon black tail gas is selected as the activating agent, and the mass ratio of the carbon black tail gas to the primary carbide is 0.8:1. The quenching gradient is reduced synchronously at 950℃, the pressure in the quenching section is controlled at 0.08MPa, and the activation reaction is completed by keeping the temperature at 850℃ for 6h. The obtained activated porous carbon is detected to have a specific surface area of 1850m 2 / g, micropores account for 90%, mesopores account for 10%, the total pore volume is 0.85cm 3 / g, the average pore size is 1.86nm, and the yield of the porous carbon is 24.4%.
[0063] In the silicon loading process, the activated porous carbon is first crushed to a particle size of D50=8 microns, then treated by grading and impurity removal, and then placed in a fluidized bed chemical vapor deposition device. First, 100% of the activated porous carbon is introduced into the silane gas, and the reaction is carried out at 510℃ for 10h. Then, 10% of the activated porous carbon is introduced into the acetylene gas, and the reaction is carried out at 600℃ for 12h. In the finally obtained silicon-carbon material, the particle size of the nano-silicon is 1.86nm, the reversible specific capacity is 1900mAh / g, the first charge-discharge coulombic efficiency is 93.3%, and all performance indicators are excellent.
[0064] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application, and all should be covered in the scope of the claims of the present application.
Claims
1. A method for preparing porous carbon and silicon-carbon materials based on pyrolysis of carbon sources, characterized in that: The method comprises the following steps: S1, carbon pyrolysis carbonization process: selecting ethylene tar, coal tar, anthracene oil, oil sludge as carbonaceous raw materials, selecting p-xylene glycol, benzaldehyde and its related derivatives as crosslinking agent, the carbonaceous raw materials after mixing pretreatment or the composite precursor generated by reaction are transported to the special reaction furnace containing pyrolysis section and quenching section, wherein the pyrolysis section and the quenching section are directly connected through a flow guide pipeline, and the inner diameter of the pipeline is 1 / 3-1 / 2 of the diameter of the reaction furnace; inert protective atmosphere is introduced into the pyrolysis section, and primary carbonates are generated at 400-1800℃ for 1-4h; S2, continuous activation process: the primary carbonates directly enter the quenching section, and the quenching rate is controlled at 50-200℃ / min; carbon dioxide, water vapor, purified carbon black tail gas or their mixture gas is introduced into the quenching section as an activating agent during the quenching process, and the temperature is lowered synchronously with the quenching gradient at 800-1500℃, and the activation reaction is completed at 600-1000℃ for 0.5-8h to obtain activated porous carbon; S3, silicon loading process: the activated porous carbon is crushed, graded, and impurity-removed, and is placed in a rotary furnace and / or a fluidized bed chemical vapor deposition device, and 30%-250% of the mass of the activated porous carbon is introduced into silane gas, and is reacted at 420-600℃ for 1-24h, and then 1%-20% of the mass of the activated porous carbon is introduced into single or mixed carbon source gas such as methane, acetylene, propylene, butene, and is reacted at 500-750℃ for 1-24h to obtain silicon-carbon material; 2. The method according to claim 1, wherein: The carbonaceous raw material is selected from at least one of organic chemical raw materials and chemical by-products containing carbon.
3. The method according to claim 1, wherein: The crosslinking agent is selected from at least one of p-xylene glycol, dimethyl terephthalate, dioctyl terephthalate, 2-nitro-p-xylene glycol, p-xylene glycol diacetate, 4-hydroxymethyl benzyl alcohol, p-xylylformaldehyde, benzaldehyde, benzoic acid, benzyl alcohol, cinnamyl aldehyde, m-nitrobenzaldehyde, o-nitrobenzaldehyde, p-nitrobenzaldehyde, phenylacetaldehyde, benzyl cyanide, benzoin, and o-hydroxybenzaldehyde, and the p-terephthalic acid and benzaldehyde derivatives containing hydroxyl groups are preferred.
4. The method according to claim 1, wherein: In step S2, the activating agent is selected from one or a combination of carbon dioxide, water vapor or purified carbon black tail gas; and the mass ratio of the activating agent to the primary carbonates is 0.2:1-5:1; and the heating and cooling rate of the activation reaction is the natural temperature field gradient from the pyrolysis section to the quenching section.
5. The method according to claim 1, wherein: The "purified carbon black tail gas" in step S2 is specifically: the production of carbon black tail gas removes floating powder non-gas impurities by filtration, removes nitrogen and sulfur-containing gas impurities by gas filtration, and the obtained purified carbon black tail gas is an activation gas containing a certain proportion of carbon dioxide and water vapor.
6. The method according to claim 1, wherein: The pressure of the pyrolysis section of the special reaction furnace is controlled at 0.1-0.3MPa, and the pressure of the quenching section is controlled at 0.05-0.1MPa, so as to ensure stable gas flow and prevent product agglomeration.
7. A porous carbon and silicon-carbon material obtainable by the process according to any one of claims 1 to 6, characterized in that: The specific surface area of the porous carbon is 800-2500 m 2 / g, and micropores account for 40%-96% and mesopores account for 4%-60%, and the total pore volume is 0.4-1.8 cm 3 / g; the particle size of nanosilicon in the silicon-carbon material is 0.4-5 nm, the reversible specific capacity is 800-2600 mAh / g, the first charge-discharge coulombic efficiency is >92%, and the capacity retention rate after 1000 charge-discharge cycles is ≥80%.