A process for the production of activated carbon

Abstract

The application relates to the technical field of activated carbon, and particularly discloses a production process of activated carbon. The production process of activated carbon comprises the following steps: mixing bamboo fibers, coconut shell powder and walnut shell powder, and crushing the mixture to obtain a mixed carbon source; adding a biomass porous template agent and a composite pore-forming agent containing hollow titanate microspheres and ZIF-8, and then performing ultrasonic dispersion and standing; the mixture is first kept at 280-320 DEG C for 2-4 hours in an air atmosphere, and then carbonized at 500-600 DEG C for 1-2 hours in a nitrogen atmosphere; then the temperature is increased to 800-900 DEG C, and HF steam is passed through for 2-3 hours; the carbonized intermediate is obtained after cooling; the carbonized intermediate is washed to be neutral, and then vacuum dried to obtain the activated carbon. The activated carbon prepared by the process effectively improves the proportion of macropores, the proportion of pores larger than 50 nm reaches more than 80%, and the activated carbon can well adapt to the comprehensive use requirements of new energy batteries on the charging and discharging rate, the power density and the energy density.

Description

Technical Field

[0001] This application relates to the field of activated carbon technology, and more specifically, to a process for producing activated carbon. Background Technology

[0002] Activated carbon, as a typical porous adsorbent, possesses core characteristics such as large specific surface area, well-developed pore structure, and abundant surface functional groups. Its main component is amorphous carbon, and it exhibits excellent physicochemical stability, being resistant to acids, alkalis, and high temperatures, insoluble in water and various organic solvents. Furthermore, it boasts high mechanical strength and is recyclable. These comprehensive properties enable activated carbon to demonstrate irreplaceable application value in multiple fields: in gas-phase adsorption, it can be used for industrial waste gas purification, indoor air treatment, and natural gas purification; in liquid-phase treatment, it can efficiently adsorb organic pollutants, inorganic impurities, and colloidal particles in water; in addition, it can specifically remove harmful heavy metal ions from water bodies. It is a high-performance adsorbent widely used in environmental protection, chemical industry, and food processing, playing a significant role in promoting green industrial development and improving the ecological environment.

[0003] Currently, a patent document with publication number CN102614830B discloses a method for preparing coal-based manganese magnetic activated carbon. This method uses electrolytic manganese slag and deashed coal powder as raw materials, and proceeds in three steps: First, the electrolytic manganese slag is dried, crushed, and sieved. After leaching with sulfuric acid, the pH is adjusted, and sodium fluoride solution is added, followed by multiple filtrations to obtain a manganese sulfate solution. Second, deashed coal powder of a specific particle size is mixed with the manganese sulfate solution, and sodium dodecyl sulfonate is added for adsorption. After pH adjustment, the mixture is filtered, and the filter residue is dried to obtain a precursor. Third, the precursor is mixed with potassium hydroxide and deionized water in a specific ratio to form a paste. Under nitrogen protection, the paste is first carbonized and then activated by heating. The product is then impregnated, filtered, washed, and dried to finally obtain the coal-based manganese magnetic activated carbon product. The activated carbon obtained by the above method has the advantages of large specific surface area, low production cost, and convenient recycling.

[0004] However, the activated carbon prepared by the aforementioned coal-based manganese magnetic activated carbon preparation process has significant shortcomings in meeting the requirements of new energy batteries. New energy battery systems require activated carbon to achieve both high specific surface area adsorption and rapid ion transport in the electrolyte through a specific pore size ratio (especially sufficiently large pores) to ensure redox reaction efficiency and energy conversion performance. However, conventional technologies struggle to precisely control the pore size ratio, resulting in a low proportion of >50nm large pores in the activated carbon. This hinders ion diffusion during battery charging and discharging, reducing the battery's charge / discharge rate and power density. The applicant's research indicates that in new energy battery systems, the proportion of >50nm pores in the activated carbon must reach over 80% to meet the requirements. Activated carbon prepared using existing technologies clearly fails to meet this standard, exhibiting a core defect of insufficient large pore proportion. Summary of the Invention

[0005] In order to increase the proportion of macropores in activated carbon, so that the proportion of >50nm pores in activated carbon reaches more than 80%, thereby meeting the requirements of new energy batteries for activated carbon, this application provides a production process for activated carbon.

[0006] The activated carbon production process provided in this application adopts the following technical solution:

[0007] A process for producing activated carbon includes the following steps:

[0008] (1) Mix bamboo fiber, coconut shell powder and walnut shell powder, crush them to obtain a mixed carbon source, then add biomass porous template agent and composite pore-forming agent, disperse by ultrasonication and let stand for 1-2 hours;

[0009] (2) After standing, the mixture is heated to 280℃-320℃ in air and kept at that temperature for 2-4 hours; then, under a nitrogen atmosphere, it is heated to 500-600℃ for 1-2 hours, then heated to 800-900℃ and HF steam is introduced for 2-3 hours. After cooling, a carbonization intermediate is obtained. The carbonization intermediate is washed with deionized water until neutral and then dried under vacuum to obtain activated carbon.

[0010] In step (1), the biomass porous template agent is rice husk ash that has been puffed at high temperature; the composite pore-forming agent includes hollow titanate microspheres and metal-organic framework material ZIF-8.

[0011] By adopting the above technical solution, bamboo fiber, coconut shell powder, and walnut shell powder are selected as a carbon source, and the three form a complementary structure: bamboo fiber has a natural fibrous skeleton, and after carbonization, it can retain long strip-shaped pore channels, providing an initial skeleton for the formation of macropores; coconut shell powder and walnut shell powder have rich microporous / mesoporous precursor structures, and after carbonization, they can supplement small and medium pore sizes, avoiding the pore channel uniformity caused by a single carbon source.

[0012] High-temperature puffed rice husk ash contains 35%-42% natural porosity, and its main component is amorphous silica, which has a stable porous framework structure. Adding it as a template agent to a mixed carbon source allows, on the one hand, the natural macropores of the rice husk ash to be directly replicated into the carbonized carbon framework, forming initial macroporous channels; on the other hand, the silica framework of the rice husk ash is selectively etched away during the subsequent HF steam treatment stage (SiO2 + 4HF = SiF4↑ + 2H2O). This etching process not only avoids damaging the macroporous structure of the carbon framework but also expands the pore size through the mild etching effect of HF, further expanding the initial macropores into effective transport channels of 80-200 nm, while avoiding the pore collapse problem caused by the high-temperature decomposition of traditional organic template agents.

[0013] When hollow mesoporous barium strontium titanate microspheres are added to a mixed carbon source, the hollow structure of the microspheres can directly serve as a rigid template, supporting the carbon skeleton to form macropores of the corresponding size during carbonization. Simultaneously, the mesopores in the shell act as connecting channels, opening up the micropores of the carbon source itself and the hollow macropores, avoiding ion transport dead zones caused by isolated macropores. ZIF-8 possesses a rich microporous structure, gradually decomposing into zinc oxide and carbon nanoparticles during the carbonization stage at 800-900℃. On one hand, the pores left after ZIF-8 decomposition can form transitional channels of 50-100 nm, filling the size gap between the hollow titanate microspheres (80-200 nm) and the carbon source micropores, constructing a continuous transport path. On the other hand, the zinc oxide produced by ZIF-8 decomposition generates volatile ZnF2 under the action of HF vapor. During volatilization, this etches the pore walls of the carbon skeleton, further expanding the pore size and transforming some transitional pores into macropores >50 nm, thus significantly increasing the proportion of macropores. The above solution fundamentally solves the core problem of insufficient proportion of macropores >50nm in existing technologies, and ultimately achieves the technical goal of macropore proportion ≥80%.

[0014] Optionally, in step (1), the mixing mass ratio of bamboo fiber, coconut shell powder and walnut shell powder is (3-5):(1-3):1.

[0015] By adopting the above technical solution, the mixing mass ratio of bamboo fiber, coconut shell powder and walnut shell powder is limited to (3-5):(1-3):1. The core advantage lies in the precise control of the skeleton support capacity and porosity of the carbon source: bamboo fiber has the highest proportion, which can ensure sufficient fibrous skeleton, provide more initial channels for the formation of macropores, and avoid the lack of macropore skeleton due to insufficient bamboo fiber.

[0016] Optionally, the amount of the biomass porous template agent added is 17%-20% of the mass of the mixed carbon source; the amount of the composite pore-forming agent added is 21%-36% of the mass of the mixed carbon source.

[0017] By adopting the above technical solutions, the amount of biomass porous template agent (15%-20%) can provide a sufficient natural macroporous framework, while avoiding excessive dosage that would dilute the carbon content and affect the conductivity of activated carbon; the amount of composite pore-forming agent (25%-30%) can ensure sufficient rigid template and transition channels, avoiding insufficient dosage that would result in an insufficient number of macropores, or excessive dosage that would result in template agent residue and increase production costs, ultimately ensuring that the proportion of macropores remains stable and meets the standards.

[0018] Optionally, the biomass porous template agent is rice husk ash that has undergone high-temperature puffing treatment, and the biomass porous template agent is prepared by the following method:

[0019] Soak rice husks in hydrochloric acid solution for 6-8 hours, then wash and dry at 90-100℃ for 8-12 hours. Then, calcine the soaked rice husks at 600-700℃ for 2-4 hours. After natural cooling, collect the rice husk ash. Mix the rice husk ash with hydrogen peroxide solution at a solid-liquid ratio of 1:(6-8), transfer to a high-pressure reactor, and react at 100-120℃ for 4-6 hours. After filtration, wash and vacuum dry for 6-8 hours to obtain a biomass porous template agent.

[0020] Optionally, the hydrochloric acid has a mass concentration of 3%-5%; the hydrogen peroxide solution has a mass concentration of 25%-30%.

[0021] By adopting the above technical solution, the preparation method of rice husk ash and the concentration parameters of hydrochloric acid and hydrogen peroxide are clarified. The core advantage lies in improving the porosity and stability of the template agent. Soaking in 3%-5% hydrochloric acid can effectively remove metal impurities (such as calcium and magnesium ions) in rice husks, avoiding impurities from clogging the pores. 25%-30% hydrogen peroxide under high pressure at 100-120℃ can oxidize the residual organic matter in rice husks, and at the same time expand the natural pores through the "oxidative expansion" effect, so that the proportion of >50nm pores in rice husk ash increases to more than 35%. Calcination at 600-700℃ can remove the organic components in rice husks, retain a stable siliceous porous framework, and provide a reliable template for the subsequent "replication" of macropores, avoiding the low proportion of macropores due to insufficient porosity of the template agent.

[0022] Optionally, the mass ratio of hollow titanate microspheres to metal-organic framework material ZIF-8 in the composite pore-forming agent is (2-4):1.

[0023] Optionally, the hollow titanate microspheres are prepared using the following method:

[0024] A. Dissolve strontium nitrate and barium nitrate in deionized water to form a mixed salt solution, then add tetrabutyl titanate solution, stir at 300-500 rpm for 30-50 min, then add hexadecyltrimethylammonium bromide, and stir at 50-60℃ for 1-2 h to form a sol;

[0025] B. Transfer the sol obtained in step A to a polytetrafluoroethylene reactor and react at a constant temperature of 180-190℃ for 12-16 hours. After cooling, centrifuge for 10-20 minutes to collect the precipitate, and then wash and vacuum dry to obtain the precursor powder.

[0026] C. Place the precursor powder obtained in step B into a muffle furnace, heat it to 600-650℃, keep it at that temperature for 3-5 hours, and then cool it naturally to obtain hollow titanate microspheres.

[0027] Optionally, in step A, the mass ratio of strontium nitrate, barium nitrate, and deionized water is (8-10):(3-5):100.

[0028] Optionally, in step A, the mass concentration of the tetrabutyl titanate solution is 18%-20%, and the amount of tetrabutyl titanate solution added is 30%-35% of the mass of the mixed salt solution; the amount of hexadecyltrimethylammonium bromide added is 5%-7% of the mass of the mixed salt solution.

[0029] By adopting the above technical solution, the strontium nitrate / barium nitrate ratio, tetrabutyl titanate concentration and dosage, and hexadecyltrimethylammonium bromide dosage of hollow titanate microspheres are clearly defined. The core advantage lies in ensuring the hollow structure and mesopore distribution of the microspheres, providing a precise template for macropore control: the mass ratio of strontium nitrate, barium nitrate and deionized water is (8-10):(3-5):100. The crystal structure of titanate can be controlled by strontium-barium doping to ensure that the microsphere shell forms uniform 25-35nm mesopores, avoiding mesopore blockage caused by excessive shell thickness; the 18%-20% tetrabutyl titanate solution can ensure the uniformity of the microsphere shell thickness, avoiding the collapse of the hollow structure due to excessively thin shell, or the impact on mesopore connectivity due to excessively thick shell; hexadecyltrimethylammonium bromide, as a mesopore template agent, can precisely control the shell mesopore size, ensuring that the mesopores match the transition pores of ZIF-8 decomposition, realizing pore connectivity, and ultimately ensuring the supporting effect of hollow microspheres on macropores.

[0030] Optionally, in step (2), the HF vapor is introduced at a rate of 0.8-1.2 L / min.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. Because this application adopts a synergistic technical solution of mixed carbon source and dual-level pore-forming system (biomass porous template agent + composite pore-forming agent), the fibrous skeleton of bamboo fiber in the mixed carbon source provides initial support for macropores. The biomass porous template agent forms 80-200nm macropore channels through natural macropore replication and HF etching expansion. The composite pore-forming agent constructs a multi-level control mechanism of "rigid macropore template - transition channel - pore wall etching", ultimately achieving the technical goal of >80% of >50nm pores in activated carbon. This effectively solves the core defect of insufficient macropore ratio in the existing technology, meets the needs of new energy batteries for rapid ion transport in electrolyte, and improves the battery charge and discharge rate and power density.

[0033] 2. In this application, bamboo fiber, coconut shell powder, and walnut shell powder are preferably compounded in a mass ratio of (3-5):(1-3):1, and the dosage ratio of biomass porous template agent (15%-20%) and composite pore-forming agent (25%-30%) is as follows: The former precisely controls the skeleton support capacity and porosity of the carbon source, avoiding the pore channel uniformity or lack of macroporous skeleton caused by a single carbon source; the latter balances the synergistic effect of template agent and pore-forming agent, ensuring a sufficient number of macropores, avoiding excessive dilution of carbon content by template agent or increase in production cost, further ensuring that the macropore ratio is stable and meets the standard, while taking into account the conductivity and structural stability of activated carbon.

[0034] 3. The method of this application improves the proportion of natural macropores in the biomass porous template agent and the structural controllability of the artificial pore-forming agent by using a specific preparation process of high-temperature puffed rice husk ash and precise synthesis parameters of hollow titanate microspheres. Combined with an HF steam introduction rate of 0.8-1.2 L / min, the template agent is efficiently removed and the pores are optimized. Finally, a continuous transport path of "micropore-transition pore-macropore" is constructed. While ensuring that the proportion of macropores >50nm meets the standard, it also takes into account the high specific surface area of ​​activated carbon, thus meeting the dual requirements of new energy batteries for energy storage and ion transport. Detailed Implementation

[0035] The present application will be further described in detail below with reference to the embodiments.

[0036] Preparation example of biomass porous template agent

[0037] Preparation Example 1

[0038] The biomass porous template agent was prepared using the following method:

[0039] Rice husks were soaked in a 3% hydrochloric acid solution for 6 hours, with stirring every 2 hours. After filtration, the husks were washed with deionized water until neutral, dried at 90℃ for 8 hours, and then pulverized and passed through a 0.15mm sieve. The soaked rice husks were placed in a muffle furnace and heated to 600℃ at a heating rate of 10℃ / min in air atmosphere, and calcined for 2 hours. After natural cooling, the rice husk ash was collected. The rice husk ash was mixed with 25% hydrogen peroxide at a solid-liquid ratio of 1:6, transferred to a high-pressure reactor, and reacted at 100℃ for 4 hours. After filtration, the mixture was washed with deionized water and dried under vacuum at 80℃ for 6 hours to obtain a biomass porous template agent.

[0040] Preparation Example 2

[0041] The biomass porous template agent was prepared using the following method:

[0042] Rice husks were soaked in a 4% hydrochloric acid solution for 7 hours, with stirring every 2 hours. After filtration, the husks were washed with deionized water until neutral, dried at 95℃ for 10 hours, and then pulverized and passed through a 0.15mm sieve. The soaked rice husks were placed in a muffle furnace and heated to 650℃ at a heating rate of 10℃ / min in air atmosphere, and calcined for 3 hours. After natural cooling, the rice husk ash was collected. The rice husk ash was mixed with 28% hydrogen peroxide at a solid-liquid ratio of 1:7, transferred to a high-pressure reactor, and reacted at 110℃ for 5 hours. After filtration, the mixture was washed with deionized water and dried under vacuum at 80℃ for 7 hours to obtain a biomass porous template agent.

[0043] Preparation Example 3

[0044] The biomass porous template agent was prepared using the following method:

[0045] Rice husks were soaked in a 5% hydrochloric acid solution for 8 hours, stirring every 2 hours. After filtration, the husks were washed with deionized water until neutral, dried at 100℃ for 12 hours, and then pulverized and passed through a 0.15mm sieve. The soaked rice husks were placed in a muffle furnace and heated to 700℃ at a heating rate of 10℃ / min in air atmosphere, and calcined for 4 hours. After natural cooling, the rice husk ash was collected. The rice husk ash was mixed with 30% hydrogen peroxide at a solid-liquid ratio of 1:8, transferred to a high-pressure reactor, and reacted at 120℃ for 6 hours. After filtration, the mixture was washed with deionized water and dried under vacuum at 80℃ for 8 hours to obtain a biomass porous template agent.

[0046] Preparation example of hollow titanate microspheres

[0047] Preparation Example 4

[0048] Hollow titanate microspheres were prepared using the following method:

[0049] A. Dissolve 10 kg of strontium nitrate and 3 kg of barium nitrate in 100 kg of deionized water to form a mixed salt solution. Then add 33.9 kg of 18% tetrabutyl titanate solution (solvent is ethylene glycol). Stir at 300 rpm for 30 min, then add 5.65 kg of cetyltrimethylammonium bromide. Stir at 50°C for 1 h to form a sol.

[0050] B. Transfer the sol obtained in step A to a polytetrafluoroethylene reactor and react at a constant temperature of 180°C for 12 hours. After cooling, centrifuge at 8000 rpm for 10 minutes to collect the precipitate. After washing and vacuum drying, the precursor powder is obtained.

[0051] C. Place the precursor powder obtained in step B into a muffle furnace, heat it to 600°C, keep it at that temperature for 3 hours, and then cool it naturally to obtain hollow titanate microspheres.

[0052] Preparation Example 5

[0053] Hollow titanate microspheres were prepared using the following method:

[0054] A. Dissolve 9 kg of strontium nitrate and 4 kg of barium nitrate in 100 kg of deionized water to form a mixed salt solution. Then add 37.3 kg of 19% tetrabutyl titanate solution (solvent: ethylene glycol). Stir at 400 rpm for 40 min, then add 6.78 kg of cetyltrimethylammonium bromide. Stir at 55°C for 1.5 h to form a sol.

[0055] B. Transfer the sol obtained in step A to a polytetrafluoroethylene reactor and react at a constant temperature of 185°C for 14 hours. After cooling, centrifuge at 8000 rpm for 15 minutes to collect the precipitate. After washing and vacuum drying, the precursor powder is obtained.

[0056] C. Place the precursor powder obtained in step B in a muffle furnace, heat it to 625°C, keep it at that temperature for 4 hours, and then cool it naturally to obtain hollow titanate microspheres.

[0057] Preparation Example 6

[0058] Hollow titanate microspheres were prepared using the following method:

[0059] A. Dissolve 8 kg of strontium nitrate and 5 kg of barium nitrate in 100 kg of deionized water to form a mixed salt solution. Then add 39.5 kg of 20% tetrabutyl titanate solution (solvent is ethylene glycol). Stir at 500 rpm for 50 min, then add 7.91 kg of cetyltrimethylammonium bromide. Stir at 60℃ for 2 h to form a sol.

[0060] B. Transfer the sol obtained in step A to a polytetrafluoroethylene reactor and react at a constant temperature of 190°C for 16 hours. After cooling, collect the precipitate by centrifugation at 8000 rpm for 20 minutes. After washing and vacuum drying, obtain the precursor powder.

[0061] C. Place the precursor powder obtained in step B in a muffle furnace, heat it to 650°C, keep it at that temperature for 5 hours, and then cool it naturally to obtain hollow titanate microspheres.

[0062] Example

[0063] Example 1

[0064] A process for producing activated carbon includes the following steps:

[0065] (1) Bamboo fiber, coconut shell powder and walnut shell powder were mixed and crushed to a particle size of 0.5 mm to obtain a mixed carbon source. Then, a biomass porous template agent and a composite pore-forming agent were added, and the mixture was ultrasonically dispersed and allowed to stand for 1 h to obtain a mixture. Among them, the biomass porous template agent was selected from Preparation Example 1; the composite pore-forming agent included hollow titanate microspheres from Preparation Example 4 and metal-organic framework material ZIF-8. The raw material ratio is shown in Table 1.

[0066] (2) The mixture after standing was heated to 280°C in air at a heating rate of 2°C / min and held for 4 hours; then in nitrogen atmosphere (flow rate of 1.5 L / min), it was heated to 500°C at a heating rate of 4°C / min for 2 hours, and then heated to 800°C and HF steam was introduced and held for 3 hours at a rate of 0.8 L / min; after cooling, a carbonization intermediate was obtained, which was washed with deionized water until neutral and then dried under vacuum to obtain activated carbon.

[0067] Example 2

[0068] A process for producing activated carbon includes the following steps:

[0069] (1) Bamboo fiber, coconut shell powder and walnut shell powder were mixed and crushed to a particle size of 0.5 mm to obtain a mixed carbon source. Then, a biomass porous template agent and a composite pore-forming agent were added, and the mixture was ultrasonically dispersed and allowed to stand for 1.5 h to obtain a mixture. Among them, the biomass porous template agent was selected from Preparation Example 2; the composite pore-forming agent included hollow titanate microspheres and metal-organic framework material ZIF-8 from Preparation Example 4. The raw material ratio is shown in Table 1.

[0070] (2) The mixture after standing was heated to 300°C in air at a heating rate of 2°C / min and held for 3h; then in nitrogen atmosphere (flow rate of 1.5L / min), it was heated to 550°C at a heating rate of 4°C / min for 1.5h, and then heated to 850°C and HF steam was introduced and held for 2.5h at a rate of 1.0L / min; after cooling, a carbonization intermediate was obtained, which was washed with deionized water until neutral and then dried under vacuum to obtain activated carbon.

[0071] Example 3

[0072] A process for producing activated carbon includes the following steps:

[0073] (1) Bamboo fiber, coconut shell powder and walnut shell powder were mixed and pulverized to an average particle size of 0.5 mm to obtain a mixed carbon source. Then, a biomass porous template agent and a composite pore-forming agent were added, and the mixture was ultrasonically dispersed and allowed to stand for 2 hours to obtain a mixture. Among them, the biomass porous template agent was selected from Preparation Example 3; the composite pore-forming agent included hollow titanate microspheres and metal-organic framework material ZIF-8 from Preparation Example 4. The raw material ratio is shown in Table 1.

[0074] (2) The mixture after standing was heated to 320°C in air at a heating rate of 2°C / min and held for 4 hours; then in nitrogen atmosphere (flow rate of 1.5L / min), it was heated to 600°C at a heating rate of 4°C / min for 1 hour, and then heated to 900°C and HF steam was introduced and held for 2 hours at a rate of 1.2L / min; after cooling, a carbonization intermediate was obtained, which was washed with deionized water until neutral and then dried under vacuum to obtain activated carbon.

[0075] Table 1. Raw material components and proportions (kg) in Examples 1-3

[0076]

[0077] Example 4

[0078] The production process of activated carbon differs from that of Example 1 in that the hollow titanate microspheres used in this example are the hollow titanate microspheres prepared in Preparation Example 5.

[0079] Example 5

[0080] The production process of activated carbon differs from that of Example 1 in that the hollow titanate microspheres used in this example are the hollow titanate microspheres prepared in Preparation Example 6.

[0081] Comparative Example

[0082] Comparative Example 1

[0083] Activated carbon was prepared according to the method in Example 1 of the publication entitled "Preparation Method of Coal-based Manganese Magnetic Activated Carbon" (CN102614830B).

[0084] Comparative Example 2

[0085] The production process of activated carbon differs from that of Example 1 in that bamboo fiber is not added in step (1) of this comparative example, and coconut shell powder is used instead.

[0086] Comparative Example 3

[0087] The production process of activated carbon differs from that of Example 1 in that no biomass porous template agent is added in step (1) of this comparative example.

[0088] Comparative Example 4

[0089] The production process of activated carbon differs from that of Example 1 in that no composite pore-forming agent is added in step (1) of this comparative example.

[0090] Comparative Example 5

[0091] The production process of activated carbon differs from that of Example 1 in that, in step (1) of this comparative example, only 1.5 kg of composite pore-forming agent is used to prepare the hollow titanate microspheres obtained in Example 4.

[0092] Comparative Example 6

[0093] The production process of activated carbon differs from that of Example 1 in that the composite pore-forming agent in step (1) of this comparative example is only 1.5 kg of metal-organic framework material ZIF-8.

[0094] Performance testing

[0095] The performance indicators of the activated carbons prepared in Examples 1-5 and Comparative Examples 1-6 were tested, and the results are shown in Table 2.

[0096] Table 2 Detection Results

[0097]

[0098] As shown in Table 2, the proportion of pores >50nm in Examples 1-5 remained stable at 87.95%-91.26%, far exceeding the target value of 80%, and the specific surface area of ​​the prepared activated carbon remained at 453.62-482.57m². 2 With a pore volume of 0.587-0.635 mL / g, the process in this application demonstrates that while increasing the proportion of macropores, it does not sacrifice the specific surface area and pore volume brought by small and medium pores, achieving a balance between "macropore transport + small and medium pore storage". Therefore, it has significant advantages in the field of electrode materials for new energy batteries, providing an efficient transport channel for electrolyte ions (based on macropores) while ensuring charge storage capacity through small and medium pores, which is well adapted to the comprehensive use requirements of new energy batteries for charge and discharge rate, power density and energy density.

[0099] The proportion of >50nm pores in Comparative Examples 1-6 is much lower than that in the Examples. Among them, Comparative Example 1 has a proportion of 45.38%. It uses the existing coal-based manganese magnetic activated carbon process, which relies solely on potassium hydroxide to activate and create pores. It is difficult to form >50nm macropores. This makes it difficult to meet the requirement that the activation process can only widen some micropores / mesopores and form >50nm macropores. As a result, ion diffusion is hindered during battery charging and discharging. This makes it difficult to meet the core requirement of the proportion of macropores in activated carbon for new energy battery systems and cannot be adapted to the use requirements of high-power batteries.

[0100] Comparative Example 2 was 58.62%. Due to the lack of bamboo fiber in the raw materials and the absence of fibrous skeleton support, it was difficult to form initial macroporous channels after carbonization. Relying solely on the microporous precursor of coconut shell powder, the proportion of macropores dropped sharply, and the pore volume (0.451 mL / g) was insufficient.

[0101] Comparative Example 3 was 65.27%. Due to the lack of biomass porous template agent in the raw material, the foundation for natural macropore replication and HF etching to expand the pores was missing. It relied solely on the single effect of the composite pore-forming agent, resulting in an insufficient number of macropores.

[0102] Comparative Example 4 had a specific surface area of ​​52.89%. Because no composite pore-forming agent was added to the raw material, the natural macropores of the biomass porous template agent alone could not expand the macropores through the rigid template and transition pores. Furthermore, the specific surface area (378.91 m²) was low. 2 The lowest / g) indicates that the composite pore-forming agent plays a core role in increasing the proportion of macropores;

[0103] In Comparative Examples 5 and 6, the composite pore-forming agents contained only a single component—Comparative Example 5 lacked ZIF-8, resulting in the absence of transition pore filling and pore wall etching, leading to isolated macropores; Comparative Example 6 lacked hollow titanate microspheres, resulting in the absence of a rigid macroporous framework. Relying solely on ZIF-8, it was difficult to form effective macropores >80nm, and thus impossible to form a continuous pore network of "rigid macroporous template-transition channels," making it difficult to meet the performance standards for activated carbon used in new energy batteries. Both examples demonstrate that the synergistic effect of the hollow titanate microsphere + ZIF-8 composite is key to achieving the required macropore ratio.

[0104] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A process for producing activated carbon, characterized in that, Includes the following steps: (1) Mix bamboo fiber, coconut shell powder and walnut shell powder, crush them to obtain a mixed carbon source, then add biomass porous template agent and composite pore-forming agent, disperse by ultrasonication and let stand for 1-2 hours; (2) After standing, the mixture is heated to 280℃-320℃ in air and kept at that temperature for 2-4 hours; then, under a nitrogen atmosphere, it is heated to 500-600℃ for 1-2 hours, then heated to 800-900℃ and HF steam is introduced for 2-3 hours. After cooling, a carbonization intermediate is obtained. The carbonization intermediate is washed with deionized water until neutral and then dried under vacuum to obtain activated carbon. The biomass porous template agent is prepared by the following method: Soak rice husks in hydrochloric acid solution for 6-8 hours, wash, and dry at 90-100℃ for 8-12 hours. Calcinate the soaked rice husks at 600-700℃ for 2-4 hours. After natural cooling, collect the rice husk ash. Mix the rice husk ash with hydrogen peroxide solution at a solid-liquid ratio of 1:(6-8), transfer to a high-pressure reactor, and react at 100-120℃ for 4-6 hours. After filtration, wash and vacuum dry for 6-8 hours to obtain the final product. The composite pore-forming agent includes hollow titanate microspheres and metal-organic framework material ZIF-8; The hollow titanate microspheres were prepared using the following method: A. Dissolve strontium nitrate and barium nitrate in deionized water to form a mixed salt solution, add tetrabutyl titanate solution, stir at 300-500 rpm for 30-50 min, then add hexadecyltrimethylammonium bromide, and stir at 50-60℃ for 1-2 h to form a sol; B. Transfer the sol obtained in step A to a polytetrafluoroethylene reactor and react at a constant temperature of 180-190℃ for 12-16 hours. After cooling, centrifuge for 10-20 minutes to collect the precipitate, and then wash and vacuum dry to obtain the precursor powder. C. Place the precursor powder obtained in step B in a muffle furnace, heat it to 600-650℃, keep it at that temperature for 3-5 hours, and then let it cool naturally to obtain the product.

2. The activated carbon production process according to claim 1, characterized in that: In step (1), the mass ratio of bamboo fiber, coconut shell powder and walnut shell powder is (3-5):(1-3):

1.

3. The activated carbon production process according to claim 1, characterized in that: The amount of the biomass porous template agent added is 17%-20% of the mass of the mixed carbon source; the amount of the composite pore-forming agent added is 21%-36% of the mass of the mixed carbon source.

4. The activated carbon production process according to claim 1, characterized in that: The hydrochloric acid has a mass concentration of 3%-5%; the hydrogen peroxide solution has a mass concentration of 25%-30%.

5. The activated carbon production process according to claim 1, characterized in that: The mass ratio of hollow titanate microspheres to metal-organic framework material ZIF-8 in the composite pore-forming agent is (2-4):

1.

6. The activated carbon production process according to claim 1, characterized in that: In step A, the mass ratio of strontium nitrate, barium nitrate, and deionized water is (8-10):(3-5):

100.

7. The activated carbon production process according to claim 1, characterized in that: In step A, the mass concentration of the tetrabutyl titanate solution is 18%-20%, and the amount of tetrabutyl titanate solution added is 30%-35% of the mass of the mixed salt solution; the amount of hexadecyltrimethylammonium bromide added is 5%-7% of the mass of the mixed salt solution.

8. The activated carbon production process according to claim 1, characterized in that: In step (2), the HF vapor is introduced at a rate of 0.8-1.2 L / min.

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