A pitch-based porous carbon material, its preparation method and application

Abstract

This invention provides a pitch-based porous carbon material, its preparation method, and its applications. The pitch-based porous carbon material is prepared using inexpensive and abundant coal tar pitch as raw material. The structure and surface chemical properties of the coal tar pitch are first controlled through a coupled suspension and oxidation method, followed by high-temperature carbonization and activation. The pitch-based porous carbon material prepared by this invention is an oxygen-rich, highly microporous carbon material with high adsorption performance. It has high microporosity, numerous oxygen-containing functional groups, large specific surface area, and uniform pore size distribution. It exhibits excellent static and dynamic adsorption properties and good stability, allowing for long-term use. The preparation method provided by this invention is simple and convenient to operate, uses inexpensive and readily available pitch as raw material, has a high carbon yield, and facilitates large-scale production of porous carbon materials, making it suitable for practical industrial applications.

Description

Technical Field

[0001] This invention relates to the field of carbon material preparation technology, and in particular to a pitch-based porous carbon material, its preparation method, and its application. Background Technology

[0002] Carbon dioxide is the primary gas causing global warming, and its treatment requires substantial economic costs. Therefore, carbon dioxide capture is of great significance for reducing carbon emissions and improving industrial economics.

[0003] Porous carbon materials, due to their advantages such as high specific surface area, rich pore structure, high chemical stability, and good electrical conductivity, have become a research hotspot in chemistry, biology, and materials science, and can be applied to the adsorption of carbon dioxide to reduce carbon emissions. In adsorption applications, the key indicators for evaluating the performance of porous carbon materials are specific surface area and pore size distribution; the larger the specific surface area and the more uniform the pore size distribution, the better the adsorption performance. Currently, for carbon-based raw materials, how to use simple and inexpensive carbon sources and how to improve the specific surface area and pore size distribution uniformity of porous carbon materials through processing methods are important problems to be solved.

[0004] Coal tar pitch is a byproduct of high-temperature coal tar separation, characterized by its low price, abundant availability, and high carbon content. In the industrial process of coal tar production, raw coal undergoes dry distillation to obtain coal tar, which is then refined through thermal distillation to produce various fractions such as light oil, naphthalene oil, anthracene oil, phenolic oil, and wash oil. The final bulk product after separation is coal tar pitch. Coal tar pitch contains abundant carbonaceous microcrystals and exhibits high reactivity, making it a potential precursor for preparing porous carbon materials. Furthermore, its good fluidity allows for easy transformation and control of its morphology and structure, thereby enabling the production of high-value-added carbon-based materials. The reuse of coal tar pitch helps improve the economic efficiency of the coal tar industry. In the existing technology, there are many technical solutions for preparing pitch-based porous carbon materials using pitch (such as Chinese patents CN111530440A and CN114751410A). However, the porous carbon materials prepared by these methods have low microporosity, uneven pore size distribution, poor stability, cannot be used for a long time, and the preparation methods are cumbersome, which is not conducive to large-scale industrial production. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects and deficiencies in the prior art and provide a method for preparing pitch-based porous carbon materials. By adopting a strategy of co-coupling suspension and oxidation methods, the structure and surface chemical properties of coal pitch are controlled, followed by high-temperature carbonization and activation, thereby preparing oxygen-rich microporous carbon materials with high adsorption performance.

[0006] A second objective of the present invention is to provide the aforementioned pitch-based porous carbon material.

[0007] The final object of the present invention is to provide the application of the aforementioned pitch-based porous carbon material.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution:

[0009] A method for preparing a pitch-based porous carbon material includes the following preparation steps:

[0010] S1. Heat the asphalt pyridine solution to 60-70°C, then add anhydrous ethanol, let it stand at a constant temperature, and then filter to obtain the precursor; or first heat the anhydrous ethanol to 60-70°C, then add the asphalt pyridine solution dropwise while stirring, mix at a constant temperature, and then filter to obtain the precursor.

[0011] S2. The precursor obtained in step S1 is heated to 300-500°C at a heating rate of 5-10°C / min under a synthesis air atmosphere and kept at the temperature for 3-5 hours to obtain an oxidized intermediate.

[0012] S3. The oxidized intermediate obtained in step S2 is carbonized at a high temperature of 500-1000℃ under a limited oxygen environment to obtain the carbonized product;

[0013] S4. Add an activator to the carbonization product and activate it under an oxygen-limited environment to obtain the activated product. After washing and drying, the pitch-based porous carbon material is obtained.

[0014] This invention uses inexpensive and abundant coal tar pitch as raw material. First, a coupled suspension method (step S1) and oxidation method (step S2) are used to pretreat the coal tar pitch, regulating its structure and surface chemical properties. Then, high-temperature carbonization (step S3) and activation (step S4) are performed to prepare an oxygen-rich, highly microporous pitch-based porous carbon material. The suspension method regulates the surface structure of the coal tar pitch, while the oxidation method introduces oxygen-containing functional groups to form a microporous structure. Compared with existing coal-based and biomass-based carbon materials, the pitch-based porous carbon material prepared by this invention has higher microporosity, pore size, and specific surface area, as well as higher adsorption performance. It also exhibits excellent chemical stability and is recyclable, providing a new approach for the preparation of carbon dioxide adsorption materials.

[0015] Further, the concentration of the asphalt pyridine solution in step S1 is 8-12% (w / v).

[0016] Preferably, the concentration of the bituminous pyridine solution is 10% (w / v).

[0017] Preferably, the constant temperature settling time is 20–30 minutes;

[0018] Preferably, the stirring is performed at a speed of 300-400 r / min for 20-30 min.

[0019] Further, in step S3, the temperature is increased to 500-1000℃ at a heating rate of 10-12℃ / min, and kept at a constant temperature for 2-5 hours to obtain the carbonized product.

[0020] Furthermore, the activator in step S4 is a chemical activator and / or water.

[0021] Furthermore, the chemical activator includes one or more of potassium hydroxide and sodium hydroxide.

[0022] Furthermore, when the activator is a chemical activator, the activation operation in step S4 is as follows: the temperature is increased to 400°C at a heating rate of 10-12°C / min, and the reaction is held at the temperature for 1 hour, then the temperature is increased to 750°C at a heating rate of 10-12°C / min, and the reaction is held at the temperature for 2 hours; when the activator is water, the activation operation in step S4 is as follows: the temperature is increased to 850°C at a heating rate of 10-12°C / min, and the reaction is held at the temperature for 2 hours.

[0023] Furthermore, the amount of activator used is as follows: when the activator is a chemical activator, the mass ratio of the activator to the carbonization product is (1-4):1; when the activator is water, the water inlet rate is 0.002 mL / min to 0.5 mL / min.

[0024] Preferably, after the carbonized product is obtained in step S3, it is washed multiple times with hydrochloric acid solution, ethanol solution, and distilled water in sequence.

[0025] Furthermore, in step S4, the washing process involves washing the activated product with hydrochloric acid.

[0026] Furthermore, the oxygen-limited environment in steps S3 and S4 is an N2 atmosphere.

[0027] The present invention also provides a pitch-based porous carbon material, which is prepared by the above-described preparation method.

[0028] Finally, this invention provides the application of the aforementioned pitch-based porous carbon material in the adsorption of carbon dioxide.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This invention uses inexpensive and abundant coal tar pitch as raw material. First, a coupled suspension and oxidation method is employed to pretreat the coal tar pitch, regulating its structure and surface chemical properties. Then, high-temperature carbonization and activation are performed to prepare an oxygen-rich, highly microporous pitch-based porous carbon material. The pitch-based porous carbon material prepared by this invention is an oxygen-rich, highly microporous carbon material with high adsorption performance. It has a high microporosity, numerous oxygen-containing functional groups, a large specific surface area, and a uniform pore size distribution. It exhibits excellent static and dynamic adsorption properties and good stability, allowing for long-term use. The preparation method provided by this invention is simple and convenient to operate, uses inexpensive and readily available pitch as raw material, and has a high carbon yield, making it easier to achieve large-scale production of porous carbon materials and facilitating practical industrial applications. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the preparation process of the asphalt-based porous carbon material according to the present invention.

[0032] Figure 2 The isothermal adsorption-desorption curves for 6 / 8C-KOH-1, 6 / 8C-KOH-2, 6 / 8C-KOH-3, and 6 / 8C-KOH-4 of this invention are shown below. Figure 2 (a) shows the isothermal adsorption-desorption curves of 6C-KOH-1 / 2 / 3 / 4. Figure 2 (b) shows the isothermal adsorption-desorption curves of 8C-KOH-1 / 2 / 3 / 4.

[0033] Figure 3 The figures show the pore size distribution curves of 6 / 8C-KOH-1, 6 / 8C-KOH-2, 6 / 8C-KOH-3, and 6 / 8C-KOH-4 of the present invention, wherein... Figure 3 (a) shows the pore size distribution curves of 6C-KOH-1 / 2 / 3 / 4. Figure 3 (b) shows the pore size distribution curves of 8C-KOH-1 / 2 / 3 / 4.

[0034] Figure 4 These are SEM images of 6C-KOH-1 and 8C-KOH-2 of the present invention, wherein... Figure 4 (a, b) are SEM images of 6C-KOH-1. Figure 4 (c, d) are SEM images of 8C-KOH-2.

[0035] Figure 5 The adsorption performance of 6C-KOH-1(a) and 8C-KOH-2(b) in flue gas after 15 cycles is shown.

[0036] Figure 6 The N2 adsorption isotherms and pore size distribution diagrams of 6C-H2O-0.002, 6C-H2O-0.05, and 6C-H2O-0.1 at -196℃ are shown.

[0037] Figure 7 The N2 adsorption isotherms and pore size distribution diagrams of 8C-H2O-0.002, 8C-H2O-0.05, and 8C-H2O-0.1 at -196℃ are shown.

[0038] Figure 8 The images are SEM images of 6C-H2O-0.1 and 8C-H2O-0.1 of the present invention at -196℃, where (ac) is the SEM image of 6C-H2O-0.1 and (df) is the SEM image of 8C-H2O-0.1.

[0039] Figure 9 Cyclic stability tests were performed on porous carbon 6C-H2O-0.1(a) and 8C-H2O-0.1(b). Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0041] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0042] The preparation method of the pitch-based porous carbon material used in the following examples is shown in the flowchart below. Figure 1 As shown, the preparation steps include the following:

[0043] S1. Asphalt nanoparticles were prepared by suspension method to obtain the precursor;

[0044] S2. The precursor is subjected to air oxidation treatment to obtain an oxidized intermediate;

[0045] S3. The oxidized intermediate is subjected to high-temperature carbonization treatment to obtain the high-temperature carbonization product;

[0046] S4. Activate the high-temperature carbonization product by adding an activator to obtain the activated product;

[0047] S5. After washing and drying the activated product, pitch-based porous carbon material is obtained.

[0048] Example 1: Preparation of Pitch-Based Porous Carbon Materials

[0049] The specific preparation steps are as follows:

[0050] S1. Using pyridine as a solvent, 1 g of pitch and 10 mL of pyridine were mixed to prepare a 1 / 10 pitch-pyridine solution. The solution was heated to 60°C in a water bath, and 50 mL of anhydrous ethanol was quickly added. The solution was kept at a constant temperature and allowed to stand for 20 min. After filtration and washing, precursor 6A was obtained.

[0051] S2. Precursor 6A was placed in a tubular pyrolysis furnace and heated to 300°C at a rate of 5°C / min under a synthesis air atmosphere, and held at that temperature for 3 hours. After cooling, oxidized intermediate 6B was obtained.

[0052] S3. The oxidized intermediate 6B was placed in a tubular pyrolysis furnace and heated to 500°C at a rate of 10°C / min, and held at that temperature for 2 hours under a N2 atmosphere for carbonization. After carbonization, it was cooled to room temperature to obtain the high-temperature carbide 6C.

[0053] S4. Mix high-temperature carbide 6C with KOH at mass ratios of 1:1, 2:1, 3:1 and 4:1 respectively, place in a tubular pyrolysis furnace, heat to 400℃ under N2 atmosphere at a heating rate of 10℃ / min, hold at the temperature for 1h, then heat to 750℃ at the same heating rate and hold at the temperature for 2h.

[0054] S5. After cooling, the activated product is washed with hydrochloric acid and dried to obtain four kinds of pitch-based porous carbon materials. According to the different ratios of the activator added in step S4, they are named 6C-KOH-1, 6C-KOH-2, 6C-KOH-3 and 6C-KOH-4.

[0055] Example 2: Preparation of Pitch-Based Porous Carbon Materials

[0056] Compared with Example 1, a different suspension method was used to treat coal tar pitch in step S1 of this example.

[0057] The specific preparation steps are as follows:

[0058] S1. Using pyridine as a solvent, 1g of asphalt and 10mL of pyridine were mixed to prepare a 1 / 10 asphalt-pyridine solution. 50mL of anhydrous ethanol was heated to 60℃ in a water bath. The 1 / 10 asphalt-pyridine solution was added dropwise to the anhydrous ethanol at a stirring rate of 300r / min. The mixture was kept at this rate for 20min. After filtration and washing, precursor 8A was obtained.

[0059] S2. Precursor 8A was placed in a tubular pyrolysis furnace and heated to 300°C at a rate of 5°C / min under a synthesis air atmosphere, and held at that temperature for 3 hours. After cooling, oxidized intermediate 8B was obtained.

[0060] S3. The oxidized intermediate 8B was placed in a tubular pyrolysis furnace and heated to 500°C at a rate of 10°C / min, and held at that temperature for 2 hours under a N2 atmosphere for carbonization. After carbonization, it was cooled to room temperature to obtain the high-temperature carbonized product 8C.

[0061] S4. Mix the high-temperature carbonization product 8C with KOH in mass ratios of 1:1, 2:1, 3:1 and 4:1 respectively, place them in a tubular pyrolysis furnace, heat them to 400℃ under N2 atmosphere at a heating rate of 10℃ / min, hold the temperature for 1h, and then heat them to 750℃ at the same heating rate and hold the temperature for 2h.

[0062] S5. After cooling, the activated product is washed with hydrochloric acid and dried to obtain four kinds of pitch-based porous carbon. According to the different ratios of the activator added in step S4, they are named 8C-KOH-1, 8C-KOH-2, 8C-KOH-3 and 8C-KOH-4.

[0063] Example 3: Preparation of Pitch-Based Porous Carbon Materials

[0064] Compared to Example 1, this example uses a different activator to treat coal tar pitch in step S4. The specific preparation steps are as follows:

[0065] S1. Using pyridine as a solvent, 1 g of pitch and 10 mL of pyridine were mixed to prepare a 1 / 10 pitch-pyridine solution. The solution was heated to 60°C in a water bath, and 50 mL of anhydrous ethanol was quickly added. The solution was allowed to stand at this temperature for 20 min. After filtration and washing, precursor 6A was obtained.

[0066] S2. Precursor 6A was placed in a tubular pyrolysis furnace and heated to 300°C at a rate of 5°C / min under a synthesis air atmosphere, and held at that temperature for 3 hours. After cooling, oxidized intermediate 6B was obtained.

[0067] S3. The oxidized intermediate 6B was placed in a tubular pyrolysis furnace and heated to 500°C at a rate of 10°C / min, and held at that temperature for 2 hours under a N2 atmosphere for carbonization. After carbonization, it was cooled to room temperature to obtain the high-temperature carbonized product 6C.

[0068] S4. The high-temperature carbonization product 6C was placed in a tubular pyrolysis furnace and heated to 850°C in a N2 atmosphere at a heating rate of 10°C / min. The temperature was then maintained for 2 hours. During the temperature maintenance, the water inlet rate of the steam generator was controlled (the water inlet rates were 0.002 mL / min, 0.05 mL / min, and 0.1 mL / min, respectively) to activate the product.

[0069] S5. After the activated product is cooled, three kinds of pitch-based porous carbon materials are obtained. According to the different amounts of water added in step S4, the obtained pitch-based porous carbon materials are named 6C-H2O-0.002, 6C-H2O-0.05, and 6C-H2O-0.1.

[0070] Example 4: Preparation of Pitch-Based Porous Carbon Materials

[0071] Compared to Example 3, this example uses a different suspension method to treat coal tar pitch in step S1. The specific preparation steps are as follows:

[0072] S1. Using pyridine as a solvent, 1g of asphalt and 10mL of pyridine were mixed to prepare a 1 / 10 asphalt-pyridine solution. 50mL of anhydrous ethanol was heated to 60℃ in a water bath. The 1 / 10 asphalt-pyridine solution was added dropwise to the anhydrous ethanol at a stirring rate of 300r / min. The temperature was kept constant at this rate for 20min. After filtration and washing, precursor 8A was obtained.

[0073] S2. Precursor 8A was placed in a tubular pyrolysis furnace and heated to 300°C at a rate of 5°C / min under a synthesis air atmosphere, and held at that temperature for 3 hours. After cooling, oxidized intermediate 8B was obtained.

[0074] S3. The oxidized intermediate 8B was placed in a tubular pyrolysis furnace and heated to 500°C at a rate of 10°C / min, and held at that temperature for 2 hours under a N2 atmosphere for carbonization. After carbonization, it was cooled to room temperature to obtain the high-temperature carbonized product 8C.

[0075] S4. The high-temperature carbonization product 8C was placed in a tubular pyrolysis furnace and heated to 850°C in a N2 atmosphere at a heating rate of 10°C / min. The temperature was then held for 2 hours. During the holding period, the water inlet rate of the steam generator was controlled (the water inlet rates were 0.002 mL / min, 0.05 mL / min, and 0.1 mL / min, respectively) to activate the product.

[0076] S5. After the activated product is cooled, three kinds of pitch-based porous carbon materials are obtained. According to the different amounts of water added in step S4, the obtained pitch-based porous carbon materials are named 8C-H2O-0.002, 8C-H2O-0.05, and 8C-H2O-0.1.

[0077] Example 5: Testing of Pitch-Based Porous Carbon Materials

[0078] The eight pitch-based porous carbon materials obtained in Examples 1 and 2 were characterized by tests.

[0079] First, the static adsorption performance of eight porous material samples was tested. The pore structure characteristics of the samples were analyzed using the N2 adsorption-desorption curves measured at -196℃ using a fully automated physicochemical adsorption instrument. The analysis results are shown in Table 1.

[0080] Table 1 Pore structure parameters of porous carbon materials

[0081]

[0082] Note: a refers to the specific surface area obtained based on the BET method; b refers to the average pore size; c refers to the total pore volume calculated at a pressure of 0.995; d refers to the micropore volume; e refers to the microporosity, i.e., V0. micro / V total The value of .

[0083] It is evident that, considering both specific surface area and microporosity, among the four samples in Example 1, 6C-KOH-1 exhibits the highest microporosity and the largest specific surface area; among the four samples in Example 2, 8C-KOH-2 exhibits the highest microporosity and a relatively large specific surface area.

[0084] Isothermal adsorption-desorption performance tests were conducted on eight samples, and the test results are as follows: Figure 2 As shown, the N2 adsorption-desorption isotherms of all porous carbons exhibit a complex structure of micropores and mesopores, reflecting high absorption under low relative pressure, and possessing the unique structural characteristics of microporous carbon materials.

[0085] Pore ​​size distribution tests were performed on eight samples, and the results are as follows: Figure 3 As shown, the pore size of the adsorbent is mainly distributed within 4 nm, and pores smaller than 2 nm account for the majority, indicating that porous carbon materials have a high micropore volume, which is beneficial for CO2 adsorption.

[0086] Based on the above comprehensive performance, the two samples with the best performance were selected: 6C-KOH-1 and 8C-KOH-2, and they were further characterized:

[0087] The surface morphology of the two samples was observed using transmission electron microscopy (SEM), and the results are as follows: Figure 4 As shown, the surfaces of 6C-KOH-1 and 8C-KOH-2 were severely etched by KOH and largely became uneven and porous, losing the original morphology of the precursors. Figure 4 In (b) and (d), the loose surface and abundant pores of the porous carbon of 6C-KOH-1 and 8C-KOH-2 can be clearly seen, respectively. Some of these pores are micropores produced by KOH etching; the other part is that the precursor particles are destroyed by KOH, the original surface structure is destroyed, and the broken structure is re-accumulated to form many new pores.

[0088] The degree of defect in porous carbon was characterized by Raman spectroscopy. The results showed that after KOH activation treatment, some graphitic carbon in the precursor was transformed into disordered carbon, thereby enhancing its CO2 capture ability. In addition, compared with commercial activated carbon, coal tar pitch-based porous carbon has a relatively high degree of graphitization, which is attributed to the rich carbon microcrystalline structure of the precursor.

[0089] The CO2 adsorption performance of 6C-KOH-1(a) and 8C-KOH-2(b) was tested after 15 cycles of adsorption in flue gas. The results are as follows: Figure 5 As shown, the CO2 adsorption capacity of the two types of porous carbon did not change significantly after 15 cycles of adsorption testing. Figure 5 (a) shows the dynamic saturated adsorption capacity of 6C-KOH-1 after 15 cycles. The adsorption capacity fluctuated during the cycle due to human error during the test, but the adsorption capacity only changed slightly over 15 cycles, fluctuating around 1.12 mmol / g. Additionally, from... Figure 5 (b) It can be seen that the saturated adsorption capacity of 8C-KOH-2 during the cycle is approximately 1.14 mmol / g, which is higher than that of 6C-KOH-1, consistent with the static adsorption results. The above studies indicate that porous carbon prepared by the KOH activated method has a high dynamic adsorption capacity and good stability, which is beneficial for the long-term use of the adsorbent.

[0090] Example 6: Testing of Pitch-Based Porous Carbon Materials

[0091] The eight pitch-based porous carbon materials obtained in Examples 3 and 4 were characterized by tests.

[0092] The pore structure characteristics of the samples were analyzed, and the results are shown in Table 2.

[0093] Table 2 Pore structure parameters of porous carbon materials

[0094]

[0095] Note: a refers to the specific surface area obtained based on the BET method; b refers to the average pore size; c refers to the total pore volume calculated at a pressure of 0.995; d refers to the micropore volume; e refers to the microporosity, i.e., V0. micro / V total The value of .

[0096] The data in the table show that, within the experimental conditions, among the three samples in Example 3, 6C-H2O-0.002 has the highest microporosity, reaching 92.6%, with an average pore size of 1.76 nm. However, its specific surface area is too small, far less than the other two samples. In contrast, among the three samples in Example 4, 8C-H2O-0.1 has the largest specific surface area, at 1684 m². 2 / g, at which point the pore volume is at its maximum, at 0.882cm³. 3 It has a high porosity of 76.3% and a high microporosity of 76.3%.

[0097] Isothermal adsorption-desorption performance and pore size distribution tests were performed on the three samples in Example 3. The results of the isothermal adsorption-desorption performance tests are as follows: Figure 6 As shown in (a), the N2 adsorption-desorption isotherms of all porous carbons exhibit a complex structure of micropores and mesopores, reflecting high absorption under low relative pressure, and possessing the unique structural characteristics of microporous materials. Further analysis reveals that although sample 6C-H2O-0.002 has the highest microporosity, its adsorption performance is far inferior to the other two samples. The pore size distribution test results are provided by... Figure 6 As shown in (b), the pore size of the adsorbent is mainly distributed within 4 nm, with pores smaller than 2 nm accounting for the majority, indicating that the porous carbon material has a high micropore volume, which is beneficial for CO2 adsorption. Based on the above comprehensive performance, among the three samples in Example 3, 6C-H2O-0.1 has the best performance.

[0098] Isothermal adsorption-desorption performance and pore size distribution tests were performed on the three samples in Example 4. The results of the isothermal adsorption-desorption performance tests are as follows: Figure 7 As shown in (a), the N2 adsorption-desorption isotherms of all porous carbons exhibit a complex structure of micropores and mesopores, reflecting high absorption under low relative pressure, characteristic of microporous materials; and sample 8C-H2O-0.1 shows the highest adsorption performance. The pore size distribution test results are provided by... Figure 7 As shown in (b), the pore size of the adsorbent is mainly distributed within 4 nm, with pores smaller than 2 nm accounting for the majority, indicating that the porous carbon material has a high micropore volume, which is beneficial for CO2 adsorption. Based on the above comprehensive performance, among the three samples in Example 4, 8C-H2O-0.1 has the best performance.

[0099] Furthermore, the two best-performing samples from Examples 3 and 4, 6C-H2O-0.1 and 8C-H2O-0.1, were characterized:

[0100] The surface morphology of the two samples was observed using transmission electron microscopy (SEM). The SEM image of the 6C-H2O-0.1 sample is shown below. Figure 8 As shown in (ac), the scanning electron microscope image of 8C-H2O-0.1 is as follows. Figure 8As shown in (df). Figure 8 As seen in (ac), 6C-H2O-0.1 exhibits an irregular surface morphology and a porous surface. Furthermore, a small number of spherical porous carbon particles and most irregular porous carbon particles are clearly visible. This is because during activation at high temperatures, the carbon in the small-particle precursor reacts with water vapor, causing the carbon particle size to decrease or even break, with only large-sized spherical carbon particles remaining. Figure 8 (f) It can be clearly seen that there are a large number of pore structures on the surface of 8C-H2O-0.1, and the surface is relatively rough.

[0101] The high CO2 adsorption capacities of porous carbon 8C-H2O-0.1 and 6C-H2O-0.1 were tested using a thermal comprehensive analyzer. Ten adsorption-desorption cycles were performed at 60℃ (each cycle lasted 16 min, before adsorption equilibrium was reached) to evaluate the adsorption stability of the porous carbon during the cycles. The results are as follows: Figure 9 As shown, in 10 cycles of testing, the adsorption capacities of 6C-H2O-0.1 and 8C-H2O-0.1 remained stable at 0.12 mmol / g and 0.14 mmol / g, respectively, demonstrating good stability.

Claims

1. A method for producing a pitch-based porous carbon material, characterized by, The preparation method comprises the following steps: S1. heating the asphalt pyridine solution to 60-70℃, then adding anhydrous ethanol, and filtering after constant temperature standing to obtain a precursor; or first heating the anhydrous ethanol to 60-70℃, then adding the asphalt pyridine solution drop by drop under stirring, and filtering after constant temperature mixing; S2. heating the precursor prepared in step S1 to 300-500℃ at a temperature increasing rate of 5-10℃ / min under a synthetic air atmosphere, and heating at constant temperature for 3-5h to obtain an oxidation intermediate; S3. carbonizing the oxidation intermediate prepared in step S2 at a high temperature of 500-1000℃ under a limited oxygen environment to obtain a carbonized product; S4. adding an activating agent to the carbonized product, and activating under a limited oxygen environment to obtain an activated product, and washing and drying to obtain the asphalt-based porous carbon material; The concentration of the asphalt pyridine solution is 8-12% (w / v); The activating agent in step S4 is a chemical activating agent and / or water; and the chemical activating agent is potassium hydroxide; When the activating agent is a chemical activating agent, the activation in step S4 is performed by heating to 400℃ at a temperature increasing rate of 10-12℃ / min, heating at constant temperature for 1h, then heating to 750℃ at a temperature increasing rate of 10-12℃ / min, and heating at constant temperature for 2h; when the activating agent is water, the activation in step S4 is performed by heating to 850℃ at a temperature increasing rate of 10-12℃ / min, and heating at constant temperature for 2h; The amount of the activating agent is as follows: when the activating agent is a chemical activating agent, the mass ratio of the activating agent to the carbonized product is (1-4):1; and when the activating agent is water, the water feeding rate is 0.002mL / min-0.5mL / min.

2. The method of claim 1, wherein, The washing in step S4 is washing the activated product with hydrochloric acid.

3. The preparation method according to claim 1, characterized in that, The limited oxygen environment in steps S3 and S4 is a N2 atmosphere.

4. A pitch-based porous carbon material, characterized by, The asphalt-based porous carbon material is prepared by the preparation method in any one of claims 1-3.

5. The asphalt-based porous carbon material in claim 4 is used for carbon dioxide adsorption.

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