Asphalt-based hollow activated carbon microspheres and methods for producing the same, electrode sheets, and supercapacitors

Abstract

The present invention relates to the technical field of electrochemical energy storage material preparation, and discloses asphalt-based hollow activated carbon microspheres and the preparation method thereof, electrode sheet, and supercapacitor. The preparation method of the asphalt-based hollow activated carbon microspheres includes the following steps: (1) mixing low ash asphalt with a solvent to obtain a mixed asphalt solution; (2) subjecting the mixed asphalt solution to spray pyrolysis under an inert atmosphere to obtain hollow carbon microspheres; (3) mixing the hollow carbon microspheres with an activator and activating them to obtain activated carbon; (4) subjecting the activated carbon to acid washing and water washing to remove impurities, and drying to obtain hollow activated carbon microspheres. Such a method has the characteristics of simple process, low preparation cost, and suitable for continuous production. The asphalt-based hollow activated carbon microspheres prepared by the method disclosed herein have high specific surface area, stable performance, environmental friendliness and well-defined hollow structure, and the supercapacitors prepared from such microspheres have high specific capacitance and high cycling capacity retention.

Description

Detailed description of the invention

[0001] [Technical Field] The present invention relates to the technical field of the preparation of electrochemical energy storage materials, and more particularly to the technical field of asphalt-based hollow activated carbon microspheres and methods for producing the same, electrode sheets, and supercapacitors.

[0002] [Background technology] The continued consumption of fossil fuels has not only triggered a serious energy crisis but has also led to a series of environmental problems. Therefore, the development of new renewable energy sources, such as solar and wind energy, has become a focus of research, and energy storage devices, a crucial component of these sources, have also made considerable progress. Among the many energy storage elements, supercapacitors occupy a unique position in today's energy storage industry due to their short charging time, long service life, good temperature characteristics, energy efficiency, and environmental protection.

[0003] Typically, a supercapacitor consists of electrode material, a diaphragm, an electrolyte, and an outer shell. The electrode material, as the core component of the capacitor, plays a crucial role in its performance. Carbon materials are widely used as electrode materials due to their excellent ductility, high chemical stability, and abundant surface functional groups. Among the many carbon materials, hollow carbon microspheres not only possess excellent conductivity and a very high specific surface area, but their unique hollow structure allows them to function as storage spaces for electrolyte ions. This effectively shortens the transfer distance between electrolyte ions and micropores, resulting in a higher reversible specific capacitance.

[0004] Currently, commonly used methods for preparing hollow carbon microspheres mainly include the template method, suspension polymerization, hydrothermal method, spray drying method, and high-temperature pyrolysis method. The spray method is considered the most promising technique for industrial production due to its advantages such as high speed, high efficiency, and mass production.

[0005] CN101541674A discloses a method for preparing mesoporous carbon microspheres with a large specific surface area and fine pore size, the method comprising the following steps: pre-mixing a carbon precursor, a template agent, and a solvent; forming a complex of carbon microsphere precursors by spray drying; then carbonizing at a high temperature; and finally removing the template to form activated carbon microspheres. Although the principle of such a method is simple, the formation of spheres and the distribution of carbonization increase the complexity of the process, and furthermore, the removal of the template agent afterward is necessary, and in particular, for template agents such as certain metal oxides or SiO2, the removal technique can increase the environmental and cost burden. In addition, the specific surface area of ​​the activated carbon produced is low (700 m²). 2 / g~1300m 2 (g) It cannot meet the requirements as an electrode material for supercapacitors.

[0006] CN109250716A discloses a method for preparing asphalt-based hollow activated carbon, the method comprising the following steps: uniformly mixing asphalt with a low softening point (30°C to 60°C) and asphalt with a high softening point (150°C to 360°C); adding to a spray granulator; drying at a suitable temperature of 100°C to 220°C; and then performing non-melting carbonization and activation operations to produce granules with a diameter of 0.1 mm to 2.0 mm and a specific surface area of ​​1300 m². 2 / g~1600m 2 The method involves preparing a hollow activated carbon asphalt-based solution at a concentration of / g. However, such a method also has problems such as long non-melting processing times and complex technical processes. Furthermore, the viscosity of the asphalt itself is high, and even with the addition of low-softening-point asphalt, there are still challenges in the overall fluidity of the system, making it difficult to completely volatilize the low-softening-point asphalt during spraying and to form sufficient pores.

[0007] CN106744783A discloses a method for preparing graphitized hollow carbon microspheres, the method comprising the steps of: using asphalt and additives as raw materials; and preparing graphitized hollow carbon microspheres by mixing, carbonization, acid washing and other techniques, wherein the specific surface area of ​​the resulting carbon microspheres is 100 m². 2 / g~1500m 2 The particle size is 0.1 μm to 2 μm, with a density of 0.1 μm to 2 μm. Although the manufacturing technique for this method is not complex, it still falls within the realm of preparing hollow carbon sphere structures using hard templates. In this process, the addition of metal salts, such as metal salts of Fe, Mg, Ca, and Zn, presents problems with template recovery and processing, and metal impurity ions tend to remain. These limitations restrict the applications of carbon materials, and in the field of electrochemistry in particular, metal impurity ions significantly affect the internal resistance of the material and directly impact its electrochemical performance.

[0008] In summary, while microspheres of hollow activated carbon have the potential for a wide range of applications, several problems still exist, such as the need for complex manufacturing techniques, the requirement to introduce template agents, the susceptibility to environmental pollution, and the fact that the prepared activated carbon has a low specific surface area, making it unsuitable for use as an electrode material in supercapacitors.

[0009] [Summary of the Invention] The object of the present invention is to overcome the problems of the prior art, such as having the manufacturing technology of complex hollow activated carbon microspheres, the need to introduce a templating agent, being prone to causing environmental pollution, and the prepared activated carbon having a low specific surface area and thus being unable to meet the requirements as an electrode material for supercapacitors, and to provide an asphalt-based hollow activated carbon microsphere and its manufacturing method, an electrode sheet, and a supercapacitor. Furthermore, the method has characteristics such as a simple manufacturing process and being suitable for continuous production with low manufacturing costs. The asphalt-based hollow activated carbon microspheres prepared by the method disclosed in this specification have a high specific surface area, stable performance, environmental friendliness, and a distinct hollow structure. When applied to a supercapacitor, the obtained capacitor has a high specific capacitance and a high cycle capacitance retention rate.

[0010] To achieve the above object, in a first aspect, the present invention provides a method for preparing an asphalt-based hollow activated carbon microsphere, and such a method includes the following steps: (1) Mix low-ash asphalt with a solvent to obtain a mixed asphalt solution; (2) Subject the mixed asphalt solution to spray pyrolysis under an inert atmosphere to obtain hollow carbon microspheres; (3) Mix the hollow carbon microspheres with an activating agent and activate them to obtain activated carbon; (4) Subject the activated carbon to acid washing, water washing to remove impurities, and drying to obtain asphalt-based hollow activated carbon microspheres.

[0011] In a second aspect, the present invention provides an asphalt-based hollow activated carbon microsphere prepared by the above method. Such an asphalt-based hollow activated carbon microsphere has a particle size of 5 μm to 40 μm, a specific surface area of 1600 m 2 / g to 2450 m 2 / g, and a pore volume of 1.8 m 3 / g to 3.2 m 3 / g.

[0012] In a third aspect, the present invention provides an electrode sheet comprising microspheres of asphalt-based hollow activated carbon as described in the second aspect.

[0013] In a fourth embodiment, the present invention provides a supercapacitor, such supercapacitor comprising the electrode sheet in the third embodiment described above.

[0014] The present invention can achieve the following beneficial effects through the technical solutions described above.

[0015] (1) In the present invention, the difference in physical properties between the solvent and asphalt is utilized to prepare hollow carbon microspheres having good sphericity and controllable particle size. When applied to a supercapacitor, the hollow structure can provide a temporary storage space for the electrolyte, effectively shortening the transfer distance between the electrolyte ions and the active site, resulting in a higher reversible ratio capacity.

[0016] (2) In the prior art, hollow carbon microspheres are generally produced by the hard (soft) template method, which requires the addition of silicon dioxide, metal oxides, silicates, etc. as template agents, and there are certain challenges in processing and recycling the templates. In the present invention, a self-template method using asphalt as the direct raw material is employed, and hollow structures are directly prepared by utilizing the difference in physical properties between the asphalt solute and the organic solvent. This eliminates the steps of introducing and removing templates, significantly reducing manufacturing costs and technological complexity, and solving the problem of environmental pollution caused by template removal in the template method.

[0017] (3) Asphalt has a problem in the sustainability of raw material transportation because its viscosity is excessively high, and coking that easily blocks the pipeline is likely to occur due to long-term high-temperature heating. In the present invention, by adopting a mode of co-supplying a solvent and asphalt, while a hollow structure can be obtained, on the other hand, the fluidity of asphalt can be improved, and the softening temperature of the mixed solution can also be reduced. Therefore, blockage of the transportation pipeline can be prevented, which is beneficial for long-term industrial operation.

[0018] (4) In the present invention, asphalt can be directly carbonized and pelletized in one step. Therefore, problems such as energy consumption and sphere adhesion caused by long-term preliminary oxidation and carbonization in conventional technologies such as the emulsification method and the low-temperature spraying method can be solved, and the production efficiency can be significantly improved.

[0019]

[0018] 〔Brief Description of Drawings〕 Figure 1 is a SEM graph of the hollow carbon microspheres obtained in step (2) of Example 1.

[0020] Figure 2 is a particle size distribution diagram of the asphalt-based hollow carbon microspheres prepared in Example 1.

[0021] 〔Detailed Description〕 The endpoints and any values within the ranges disclosed in this specification are not limited to exact ranges or values, and these ranges or values should be understood to be composed of values close to these ranges or values. For numerical ranges, new numerical ranges can be obtained by combining the endpoint values of the range, the endpoint values of the range and individual point values, and the individual point values with each other, and these numerical ranges should be regarded as specifically disclosed in this specification.

[0022] The present invention provides a method for preparing asphalt-based hollow activated carbon microspheres, and the method includes the following steps: (1) Mixing low-ash asphalt with a solvent to obtain a mixed asphalt solution; (2) Subject the mixed asphalt solution to spray pyrolysis under an inert atmosphere to obtain microspheres of hollow carbon; (3) Mix the microspheres of hollow carbon with an activator and activate them to obtain activated carbon; (4) Subject the activated carbon to acid washing, water washing for impurity removal, and drying to obtain microspheres of hollow activated carbon.

[0023] In the present invention, due to the combined action of the physical property differences between asphalt and the solvent and the characteristics of the spray pyrolysis process, microspheres of carbon having a hollow structure are prepared.

[0024] As a result of research, the inventors of the present invention found that when the mixed asphalt solution is atomized in a high-temperature environment, the evaporation of the organic solvent causes a situation where the moving speed of the solvent on the surface of the spherical droplets is faster than the diffusion speed of asphalt. Thereby, the concentration of asphalt on the droplet surface increases, and further solidification and carbonization occur, resulting in the obtaining of microspheres of hollow carbon having good sphericity and a controllable particle size.

[0025] The method for preparing microspheres of asphalt-based hollow activated carbon provided by the present invention has characteristics such as simple process steps, low preparation cost, and suitability for continuous production.

[0026] In the present invention, the mixing conditions in step (1) are not particularly limited as long as they can promote the dissolution of low-ash asphalt. Preferably, the mixing is preferably carried out under conditions including a temperature of 90°C to 300°C and a heating time of 0.5 hour to 2 hours.

[0027] In some embodiments of the present invention, the low-ash asphalt is preferably selected from at least one of coal-liquefied asphalt, petroleum asphalt, coal asphalt, coal-coke asphalt, synthetic asphalt, and natural asphalt. Preferably, the low-ash asphalt has an ash content of 1% by weight or less, a metal content of less than 100 ppm by mass, and a softening point of less than 250°C.

[0028] In the present invention, the solvent is not particularly limited as long as it can dissolve the low-ash asphalt. Preferably, the solvent is selected from at least one of coking oil, quinoline, pyridine, toluene, xylene, carbon disulfide, tetrahydrofuran, carbon tetrachloride, liquefied coal oil, and petroleum middle distillates.

[0029] In some embodiments of the present invention, the mass ratio of the low-ash asphalt to the solvent is preferably 1:1 to 5, and more preferably 1:1 to 2. When the above conditions are met, the prepared asphalt-based hollow activated carbon microspheres can have a high specific surface area, stable performance and a distinct hollow structure; when applied to a supercapacitor, the specific capacity and cycle capacity retention rate of the capacitor can be significantly increased.

[0030] In some embodiments of the present invention, step (2) is carried out under conditions including a nozzle hole diameter of 0.5 mm to 2 mm, a nozzle supply pressure of 0.1 MPa to 2.5 MPa, a spray pyrolysis temperature of 550°C to 800°C, a discharge temperature of 550°C to 700°C, and a raw material liquid holding time of 5 to 15 seconds.

[0031] It should be noted that the higher the proportion of asphalt in the mixed asphalt solution, the lower the spray pyrolysis temperature, the larger the nozzle pore size, and the higher the spray pressure, the larger the particle size of the hollow carbon microspheres prepared and the thinner the spherical walls become. The choice of different solvents greatly affects the viscosity of the mixed asphalt solution and simultaneously has a certain effect on the particle size. Specifically, adjustments can be made according to different practical application scenarios.

[0032] In the present invention, the mixing process in step (3) is not particularly limited as long as it is a process that can ensure that the hollow carbon microspheres and the activator are uniformly mixed. Preferably, the mixing process includes a step of pulverizing the hollow carbon microspheres and the activator with a pulverizer to mix them uniformly, wherein the rotational speed of the pulverizer is 5000 r / min to 25000 r / min.

[0033] In some embodiments of the present invention, the mass ratio of the hollow carbon microspheres to the activator is preferably 1:0.5 to 4, and more preferably 1:1 to 3.

[0034] In some embodiments of the present invention, the activator is preferably selected from at least one of potassium-containing oxides, potassium salts, KOH, alkaline earth metal salts and alkaline earth metal oxides, H3PO4 and ZnCl2, and preferably selected from at least one of KOH, K2CO3, KHCO3, KCl and KMnO4.

[0035] In some embodiments of the present invention, the activation is preferably carried out under conditions including an activation temperature of 600°C to 900°C, preferably 700°C to 800°C; an activation time of 0.5 hours to 2.5 hours; and a heating rate of 1°C / min to 10°C / min; and the activation is carried out under an inert atmosphere, preferably under nitrogen or argon.

[0036] In some embodiments of the invention, the activation can be carried out by direct heating or stepwise heating. Preferably, stepwise heating is employed. Specifically, stepwise heating means heating from room temperature to 500°C, holding it at this temperature for 0.5 to 1 hour, and then heating to an activation temperature of 600°C to 900°C, preferably 700°C to 800°C. Here, the heating rate is 1°C / min to 10°C / min.

[0037] The inventors of the present invention have found through research that, as a result of a stepwise heating preservation method, excess crystalline water in the activator can be removed in advance, thereby making the activation effect more apparent, thus achieving the objective of reducing the amount of activator added, and that the prepared asphalt-based hollow activated carbon microspheres have more stable performance.

[0038] In some embodiments of the present invention, in step (4), the acid is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid, and is preferably hydrochloric acid. The acid has a concentration of 0.5 mol / L to 3 mol / L, preferably 1 mol / L.

[0039] In the present invention, the drying conditions in step (4) are not particularly limited, but are preferably carried out under conditions including a temperature of 80°C to 120°C and a drying time of 6 to 12 hours.

[0040] In a second aspect, the present invention provides asphalt-based hollow activated carbon microspheres prepared by the above method. Such asphalt-based hollow activated carbon microspheres have a particle size of 5 μm to 40 μm and a density of 1600 m 2 / g~2450m 2 Specific surface area of ​​ / g: 1.8m² 3 / g~3.2m 3 It has a pore capacity of / g. The microspheres of hollow activated carbon prepared by the method disclosed herein have a high specific surface area, stable performance, environmental friendliness, and a distinct hollow structure.

[0041] In a third aspect, the present invention provides an electrode sheet comprising microspheres of sphalt-based hollow activated carbon as described in the second aspect.

[0042] In a fourth aspect, the present invention provides a supercapacitor comprising the electrode sheet of the third aspect described above. The supercapacitor provided by the present invention has a high specific capacitance and a high cycle capacitance retention rate.

[0043] The present invention will be described in detail below with reference to examples. Unless otherwise specified, all raw materials used in the following examples and comparative examples are commercially available.

[0044] To obtain the pore structure of the prepared samples, adsorption and desorption tests were performed using a Micromeritics ASAP2020 specific surface area and porosity analyzer according to the following procedure: First, the samples were degassed for 12 hours, and then a low-temperature adsorption and desorption test was performed under programmed control with the degassing temperature controlled to 300°C. The specific surface area of ​​the material was calculated using the BET (Brunauer-Emmett-Teller) model, and the pore capacity of the material was calculated using density functional theory (DFT).

[0045] The morphology of the sample is characterized by scanning using a HITACHI FlexSEM1000 II scanning electron microscope (SEM).

[0046] The particle size distribution of the prepared sample is measured using a Malvern MS2000 particle size analyzer.

[0047] [Example 1] Preparation of asphalt-based hollow activated carbon microspheres: (1) 1 kg of low-ash asphalt and 1.5 kg of cleaning oil were added to a stirring vessel to prepare a mixed asphalt solution with a mass ratio of 1:1.5. This mixed asphalt solution was heated to 180°C (referred to as the "mixing temperature") and mixed at a constant temperature for 0.5 hours. The mixing rate was 100 r / min; the heating rate was 5°C / min; the asphalt used was obtained from the direct coal liquefaction residue extraction and separation process of China Shenhua Coal Chemical Co., Ltd. (i.e., "coal liquefied asphalt"), with an ash content of less than 0.1% by weight and a softening point of 170°C; the cleaning oil used had a density of 1.056 g / cm³. 3 It was the conventional cleaning oil for coke.

[0048] (2) The above 180°C mixed asphalt solution was subjected to a high-temperature pyrolysis reaction by spraying it into a 750°C spray tower in a nitrogen atmosphere from a 1 mm diameter nozzle at a pressure of 0.1 MPa (referred to as the "nozzle supply pressure"), thereby forming microspheres of hollow carbon. The solid product was then collected using a high-temperature bag dust collector, allowed to cool naturally to room temperature, and excess oil gas was discharged. The piping between the nozzle and the stirring pot was maintained at 180°C, the nitrogen temperature (or spray pyrolysis temperature) was set to 750°C, the pressure to 0.08 MPa, the discharge temperature to 550°C, and the raw material holding time to 7 seconds.

[0049] (3) 5 g of the hollow carbon microspheres and 10 g of KOH (activator) were ground in a high-speed universal pulverizer and uniformly mixed. The mixture was then placed in a tubular furnace protected by nitrogen at 800°C and fired at a constant temperature for 2 hours, and then allowed to cool naturally to room temperature to obtain activated carbon microspheres. The rotation speed of the pulverizer was 24,000 r / min, and the grinding time was 10 seconds. The tubular furnace was heated in the following stages: the temperature was increased from room temperature to 500°C at a rate of 10°C / min, the temperature was maintained at 500°C for 1 hour, the temperature was increased from 500°C to 800°C at a rate of 5°C / min, and the temperature was maintained at 800°C (referred to as the "activation temperature") for 2 hours (referred to as the "activation time").

[0050] (4) The activated carbon microspheres described above were placed in a beaker, 200 mL of 1 mol / L hydrochloric acid aqueous solution was added dropwise, and the mixture was stirred thoroughly and allowed to react for 15 minutes, after which it was filtered. This procedure was repeated twice; then, sufficient deionized water was added to the filter residue obtained by acid washing, and the mixture was stirred thoroughly for 15 minutes, after which it was filtered. This procedure was repeated 3 to 5 times until the pH of the filtrate was approximately 7, in order to obtain the filter residue. Furthermore, the filter residue was dried in a forced-air drying oven at 80°C for 12 hours to obtain asphalt-based hollow activated carbon microspheres.

[0051] SEM examination was performed on the hollow carbon microspheres obtained in step (2). Figure 1 is an SEM image of these hollow carbon microspheres. From Figure 1, it can be seen that the above-mentioned hollow carbon microspheres have a clear hollow structure.

[0052] The pore structure of the microspheres of the prepared asphalt-based hollow activated carbon was examined, and the results are shown in Table 1.

[0053] The particle size of microspheres of prepared asphalt-based hollow activated carbon was examined. Figure 2 shows the particle size distribution of these prepared asphalt-based hollow activated carbon microspheres. From Figure 2, it can be seen that the particle size of the above asphalt-based hollow activated carbon microspheres is 10 μm to 20 μm.

[0054] Preparation of electrode sheets: Microspheres of asphalt-based hollow activated carbon, acetylene black, and polytetrafluoroethylene (PTFE) (15% by weight) prepared above were uniformly mixed in ethanol in a mass ratio of 8:1:1. The mixture was rolled into a thin sheet of uniform thickness using a roller, and this sheet was dried in an oven at 80°C for 12 hours. The dried sheet was cut into a circular sheet using a sheet cutter, and this circular sheet was pressed onto foamed nickel using a press to obtain an electrode sheet.

[0055] Assembly and electrochemical performance testing of supercapacitors: Three-electrode test: The electrode sheets described above were placed in a three-port electrolytic cell, a 6M KOH solution was used as the electrolyte, a platinum electrode was used as the counter electrode, and an Hg / HgO electrode was used as the reference electrode. A charge-discharge test was performed using a Metrohm Nova Autolab electrochemical workstation at a voltage range of 0-1V, a current density of 1A / g, and a test temperature of 25°C. The results of this electrochemical test are shown in Table 1.

[0056] Two-electrode test: The above electrode sheets were assembled into a button cell in the form of battery case-electrode sheet-diaphragm (polypropylene)-6M KOH-electrode sheet-battery case. The rate and long-cycle performance of the button cell were then tested using the Wuhan Land Battery Test System under a voltage range of 0-1V, a current density of 1A / g, 10,000 long-cycle charge / discharge cycles, and a test temperature of 25°C. The results of this electrochemical test are shown in Table 1.

[0057] [Examples 2-12 and Comparative Examples 1-3] Asphalt-based hollow activated carbon microspheres were prepared in the same manner as in Example 1, except that the parameters shown in Table 1 were adjusted.

[0058] The pore structure and particle size of the prepared asphalt-based hollow activated carbon microspheres were examined, and the results are shown in Table 1.

[0059] Electrode sheets were fabricated using the method of Example 1, and the supercapacitor was assembled and electrochemical performance tested according to Example 1. The test results are shown in Table 1.

[0060] [Table 1-1]

[0061] [Table 1-2]

[0062] The results in Table 1 show that the particle size of the asphalt-based hollow activated carbon microspheres prepared by the method disclosed herein is 5 μm to 40 μm, and the specific surface area is 1600 m². 2 / g~2450m 2 The pore volume is 1.8 m³ / g. 3 / g~3.2m 3 It was found that the value was / g. The specific surface area and pore volume of the asphalt-based hollow activated carbon microspheres in Examples 1-12 were clearly higher than those of Comparative Examples 1-3. When the asphalt-based hollow activated carbon microspheres prepared according to the present invention were used in a supercapacitor, the specific capacity of the supercapacitor was clearly higher than that of the comparative examples.

[0063] In conclusion, the asphalt-based hollow activated carbon microspheres prepared by the technical solution of the present invention have a large specific surface area, uniform particle size, and stable performance. Furthermore, this preparation method has features such as a simple process, low preparation cost, and suitability for continuous production. When the prepared asphalt-based hollow activated carbon microspheres are used in a supercapacitor, the supercapacitor has a high specific capacity and a high cycle capacity retention rate.

[0064] The above-described embodiments are preferred embodiments of the present invention, but are not intended to limit the invention. Within the scope of the technical concept of the present invention, many simple modifications can be made to the technical solutions of the present invention, consisting of various combinations of technical features in any other suitable manner. These simple modifications and combinations are also deemed to be within the scope of the disclosure of the present invention and are protected by the present invention. [Brief explanation of the drawing]

[0065] [Figure 1] Figure 1 is an SEM graph of the hollow carbon microspheres obtained in step (2) of Example 1. [Figure 2] Figure 2 shows the particle size distribution of asphalt-based hollow carbon microspheres prepared in Example 1.

Claims

1. A method for preparing asphalt-based hollow activated carbon microspheres, comprising the following steps: (1) Mix low-ash asphalt with a solvent to obtain a mixed asphalt solution; (2) The mixed asphalt solution is subjected to spray pyrolysis under an inert atmosphere to obtain microspheres of hollow carbon; (3) Mix the hollow carbon microspheres with an activator and activate them to obtain activated carbon; (4) Subject the activated carbon to acid washing and water washing to remove impurities, and then dry to obtain hollow activated carbon microspheres; Here, in step (2), the spray pyrolysis is carried out under conditions including a nozzle supply pressure of 0.1 MPa to 2.5 MPa, a spray pyrolysis temperature of 550°C to 800°C, and a release temperature of 550°C to 700°C. The mass ratio of the low-ash asphalt to the solvent is 1:1 to 5.

2. The method according to claim 1, In step (1) above, the mixing is carried out under conditions including a temperature of 90°C to 300°C and a heating time of 0.5 hours to 2 hours.

3. The method according to Claim 2, The low-ash asphalt is selected from at least one of coal-liquefied asphalt, petroleum asphalt, coal asphalt, coal-coke asphalt, synthetic asphalt, and natural asphalt.

4. The method according to Claim 2, The low-ash asphalt has an ash content of 1% by weight or less, a metal content of less than 100 ppm by mass, and a softening point of less than 250°C.

5. The method according to Claim 2, The solvent is selected from at least one of coking oil, quinoline, pyridine, toluene, xylene, carbon disulfide, tetrahydrofuran, carbon tetrachloride, liquefied coal oil, and petroleum middle distillates.

6. The method according to Claim 2, A method wherein the mass ratio of the low-ash asphalt to the solvent is 1:1 to 2.

7. The method according to claim 1, In step (2) above, the spray pyrolysis is carried out under conditions including a nozzle hole diameter of 0.5 mm to 2 mm.

8. The method according to claim 1, A method wherein the mass ratio of the hollow carbon microspheres to the activator is 1:0.5 to 4.

9. The method according to claim 8, A method wherein the mass ratio of the hollow carbon microspheres to the activator is 1:1 to 3.

10. The method according to claim 8, The method wherein the activator is selected from at least one of potassium-containing oxides, potassium salts, KOH, alkaline earth metal salts and alkaline earth metal oxides, H₃PO₄ and ZnCl₂.

11. The method according to claim 10, The method wherein the activator is at least one of KOH, K₂CO₃, KHCO₃, KCl, and KMnO₄.

12. The method according to claim 1, In step (3) above, the activation is carried out under conditions including an activation temperature of 600°C to 900°C; an activation time of 0.5 hours to 2.5 hours; and a heating rate of 1°C / min to 10°C / min; The activation is carried out under an inert atmosphere.

13. The method according to claim 12, The method wherein the activation temperature is 700°C to 800°C.

14. The method according to claim 12, The method wherein the inert atmosphere is nitrogen or argon.

15. The method according to claim 1, The method wherein, in step (4) above, the acid is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid.

16. The method according to claim 15, The acid is hydrochloric acid, method.

17. The method according to claim 15, The method wherein the concentration of the acid is 0.5 mol / L to 3 mol / L.

18. The method according to claim 15, The drying is carried out under conditions including a temperature of 80°C to 120°C and a duration of 6 to 12 hours.

19. A method according to any one of claims 1 to 18, The asphalt-based hollow activated carbon microspheres have a particle size of 5 μm to 40 μm and 1600 m ２ / g ~ 2450m ２ Specific surface area of ​​ / g: 1.8 m² ３ / g to 3.2m ３ A method having a pore volume of / g.

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