Preparation method of porous carbon material, product and application thereof

Abstract

The application discloses a preparation method of a porous carbon material, which comprises the following steps: (1) putting an organic carbon source into a reaction kettle, vacuumizing, and then heating to the softening point of the organic carbon source; (2) passing a gas into molecular sieves to form nano gas, passing the nano gas into the reaction kettle, forming nano bubbles in the inside of the softened organic carbon source, and controlling the inside of the reaction kettle to reach a predetermined pressure; (3) continuously heating to 50 DEG C higher than the softening point temperature of the organic carbon source, keeping warm for a period of time, cooling to room temperature to obtain a porous material, and then performing carbonization treatment to obtain the porous carbon material. The porous carbon material prepared by the method disclosed by the application has rich pore structure, high pore volume, moderate specific surface area, high regularity and uniformity of the pore structure, and narrow pore size distribution; the method realizes controllable adjustment of the pore structure, has low cost, simple process, and can realize industrialized large-scale production, and is used for preparing various porous carbons and composite materials.

Description

Technical Field

[0001] This invention relates to the technical field of carbon materials, and in particular to a method for preparing porous carbon materials, as well as their products and applications. Background Technology

[0002] Porous carbon is a class of functional carbon materials widely used in environmental protection, catalysis, chemical engineering, and energy industries. Porous carbon materials generally require the following characteristics: uniform pore size distribution, well-developed pore structure, large pore volume, and a suitable specific surface area. Traditional methods for preparing porous carbon materials often employ low carbonization temperatures and low graphitization degrees to achieve a large specific surface area, resulting in poor electronic conductivity. Furthermore, a larger specific surface area leads to a smaller average pore wall thickness supporting the pore structure. In energy storage applications, an excessively large specific surface area results in relatively thin average pore walls, potentially causing excessive volume expansion during energy storage applications, leading to pore structure collapse and performance degradation during use.

[0003] In existing technologies, conventional methods for preparing porous carbon materials mainly include activation methods and template methods. Template methods specifically include soft template methods, hard template methods, and dual template methods. While these methods can provide porous materials with good structural controllability, the preparation process is complex and cumbersome, making them unsuitable for large-scale industrial production. Activation methods specifically include chemical activation methods, catalytic activation methods, physical activation methods, and biomass carbonization activation. Traditional methods for preparing porous carbon materials often use NaOH and KOH as activators, conducting activation and pore-forming reactions at high temperatures. The pore-forming process is vigorous, making it difficult to control the activation reaction intensity and resulting in porous carbon materials with low to medium specific surface areas and uniform pore size distribution. Physical activation methods involve carbonizing the material in an inert atmosphere and then reacting it with H2O, CO2, etc., at high temperatures to create pores. This process is simple and easy to operate, but existing physical activation methods result in porous carbon materials with a predominantly microporous structure and a small specific surface area, making it difficult to achieve 1500 nm. 2 / g and above severely restrict its subsequent use. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a method for preparing porous carbon materials. The prepared porous carbon forms a rich pore structure with high pore volume and moderate specific surface area. Furthermore, the pore structure exhibits high regularity and uniformity, and a narrow pore size distribution. This preparation method enables controllable adjustment of the pore structure, and is low-cost, simple in process, and capable of large-scale industrial production for the preparation of various porous carbon materials and their composites.

[0005] The specific technical solution is as follows:

[0006] A method for preparing porous carbon materials includes the following steps:

[0007] (1) The organic carbon source is put into the reactor, and after evacuation, the temperature is raised to the softening point of the organic carbon source.

[0008] (2) After the gas is introduced into the molecular sieve, nano gas is formed. The nano gas is introduced into the reactor to form nano bubbles inside the softened organic carbon source, and the pressure inside the reactor is controlled to reach a predetermined pressure.

[0009] (3) Continue heating to 50°C above the softening point of the organic carbon source, keep it at that temperature for a period of time, and then cool it to room temperature to obtain a porous material. Then, carbonize the porous carbon material.

[0010] The preparation method disclosed in this invention utilizes molecular sieves to form nano-gas, and uses this nano-gas to form a rich pore structure inside a softened organic carbon source, with uniform pore size and structure that is not easily collapsed.

[0011] In step (1):

[0012] The organic carbon source is selected from one or more of the following: high molecular polymers, coal and coal-based derivatives, and petroleum and petroleum-based derivatives;

[0013] The polymer is selected from common polymers in the field and is not particularly limited, such as polyethylene, polyurethane, phenolic resin, urea-formaldehyde resin, etc.

[0014] The coal and coal derivatives mentioned are selected from common types in the field, such as coal pitch and coal tar.

[0015] The petroleum and its derivatives are selected from common types in the art, such as petroleum coke, paraffin wax, and various lubricants.

[0016] The amount of organic carbon source added accounts for 10-90% of the reactor volume.

[0017] The pore-forming process in step (2) of this invention is a key step in the preparation process. Experiments have shown that the pore size of the molecular sieve, the flow rate of the nano gas, and the control of the internal pressure of the reactor in this step can directly affect the pore volume, pore size, and specific surface area of ​​the prepared porous carbon material.

[0018] Preferably, the pore size of the molecular sieve is 3-50 nm. Experiments have shown that when a smaller molecular sieve (3 nm) is used, the porous carbon material prepared has a smaller pore size, but a larger specific surface area and pore volume, and the pore size distribution is concentrated. However, when a larger molecular sieve (30-50 nm) is used, the porous carbon material prepared has a larger pore size, but the specific surface area and pore volume decrease significantly, and the pore size distribution becomes wider.

[0019] Further preferably, the pore size of the molecular sieve is 3-10 nm; the porous carbon material finally prepared using the molecular sieve with this pore size has a larger pore volume and an appropriate specific surface area.

[0020] Preferably, the flow rate of the nano-gas is 8–22 L / min, the infusion time is 25–80 min, and the internal pressure of the reactor is controlled at 5–12 MPa. Experiments have shown that both excessively low and excessively high flow rates of the nano-gas lead to uneven pore size distribution and multi-peak formation in the prepared porous carbon material. This does not directly cause significant changes in the specific surface area and pore volume of the prepared porous carbon material, but it does affect its subsequent application performance. Furthermore, even with a suitable flow rate, improper control of the internal pressure of the reactor can significantly affect the specific surface area and pore volume of the prepared porous carbon material. The reasons for this may be: excessive pressure leads to insufficient mechanical strength of the internal pore walls, causing pore collapse and damaging the internal pore structure; insufficient internal pressure results in more bubbles overflowing to the softened carbon source surface, making it difficult to seal them inside, thus reducing the internal pore structure.

[0021] Further preferably, the flow rate of the nano-gas is 10-20 L / min, the introduction time is 25-40 min, and the internal pressure of the reactor is controlled at 7-9 MPa.

[0022] More preferably, the flow rate of the nano-gas is 15 L / min, the introduction time is 30 min, and the internal pressure of the reactor is controlled at 8 MPa.

[0023] In step (2):

[0024] The gas is selected from one or more of nitrogen, carbon monoxide, carbon dioxide, water vapor, and inert gases;

[0025] Preferably, the gas is selected from carbon dioxide and / or water vapor. Experiments have shown that when the gas is selected from carbon dioxide and / or water vapor, the prepared porous carbon material has a higher pore volume and specific surface area.

[0026] In step (3):

[0027] Continue heating to 60–100°C above the softening point of asphalt, and keep warm for 1–10 hours.

[0028] The carbonization process is carried out under an inert atmosphere at a temperature of 550–950°C.

[0029] Preferred:

[0030] The porous material is first crushed to a particle size of 2-10 μm and then carbonized.

[0031] This invention also discloses porous carbon materials prepared according to the above method, whose pore volume and specific surface area can be adjusted within a wide range, with a pore volume up to 1.48 cm³. 3 / g, with a specific surface area reaching up to 2354.2m². 2 / g; and the pore size distribution of porous carbon materials is relatively narrow.

[0032] This invention also discloses the application of porous carbon materials in the fields of electrochemistry, adsorption catalysis, and biomedicine.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention selects organic carbon source as raw material and utilizes a purely physical activation method to form a rich porous structure inside the softened organic carbon source by binding the gas state. The number and distribution of pores formed can be controlled by adjusting factors such as molecular sieve pore size, flow rate of nano-gas, internal pressure of the reactor, and type of nano-gas. This allows for easy control of the pore volume, specific surface area, pore size, and pore distribution of porous carbon materials according to actual production needs. The pore-forming process avoids strong alkali and complex process control, and requires no post-processing. The process steps are simple, green and environmentally friendly, and highly controllable.

[0035] The porous carbon material prepared by this invention has a wide range of adjustable pore volume and specific surface area, and can be used to prepare porous carbon materials with high pore volume, moderate specific surface area and narrow pore size distribution, thus enabling its application in a variety of downstream fields. Attached Figure Description

[0036] Figure 1 The N2 adsorption-desorption curves are for the resin-based porous carbon material prepared in Example 1.

[0037] Figure 2 The pore size distribution curve of the resin-based porous carbon material prepared in Example 1;

[0038] Figure 3 The pore size distribution curve of the porous carbon material prepared in Comparative Example 2;

[0039] Figure 4 The pore size distribution curve of the porous carbon material prepared in Comparative Example 3;

[0040] Figure 5 TEM image of the porous carbon material prepared in Comparative Example 4;

[0041] Figure 6 TEM image of the porous carbon material prepared in Comparative Example 5;

[0042] Figure 7 The N2 adsorption-desorption curves for the porous carbon material prepared in Example 9 are shown.

[0043] Figure 8 The pore size distribution curve of the porous carbon material prepared in Example 9;

[0044] Figure 9 The N2 adsorption-desorption curve of the porous carbon material prepared in Example 10;

[0045] Figure 10 The pore size distribution curve of the porous carbon material prepared in Example 10. Detailed Implementation

[0046] The present invention will be described in further detail below with reference to embodiments and comparative examples, but the implementation of the present invention is not limited thereto.

[0047] Example 1

[0048] (1) Add 60% of the volume of phenolic resin powder into the reactor, evacuate the vacuum, and set the program to heat up to 90°C. The phenolic resin powder will gradually soften completely.

[0049] (2) Nitrogen gas is introduced into the reactor. After passing through a molecular sieve with a pore size of 10 nm, the nitrogen gas forms nano gas and is then introduced into the reactor. The flow rate of the nano gas is 15 L / min and the introduction time is 30 min. Nano bubbles are formed inside the softened phenolic resin, and the pressure inside the reactor is controlled to be 8 MPa.

[0050] (3) The temperature inside the reactor is set to 170°C and kept at that temperature for 6 hours. After the temperature is kept at that temperature, the reactor is cooled to room temperature and then removed to obtain a blocky porous phenolic resin material.

[0051] (4) Crush the blocky porous phenolic resin material so that the particle size of the crushed material is controlled between 2 and 10 μm. Then put the crushed material into a carbonization furnace and heat it to 800°C under a nitrogen atmosphere for 2 hours until it is completely carbonized. After cooling to room temperature, take it out to obtain the resin-based porous carbon material.

[0052] Figure 1 The N2 adsorption-desorption curve of the resin-based porous carbon material prepared in this embodiment is shown below. Figure 1 It can be seen that the curve has the characteristics of a type I isotherm curve, indicating that the porous carbon material prepared in this embodiment has micropores and relatively narrow mesopores.

[0053] Figure 2 The pore size distribution curve of the resin-based porous carbon material prepared in this embodiment is based on... Figure 2 It can be seen that its pore size is concentrated in the range of 3 to 10 nm, more specifically in the range of 3.5 to 8.0 nm, and the pore size is uniform.

[0054] The BET, pore volume, pore size, and pore size distribution data of the resin-based porous carbon material prepared in this embodiment are listed in Table 1 below. Figure 2 The pore size distribution curve, combined with the data provided in Table 1, illustrates that micropores and small mesopores are formed in the resin-based porous carbon material prepared in this embodiment.

[0055] Example 2

[0056] The preparation process is basically the same as in Example 1, except that the pore size of the molecular sieve in step (2) is replaced with 3 nm.

[0057] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0058] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 0.5 to 5.0 nm.

[0059] Example 3

[0060] The preparation process is basically the same as in Example 1, except that the pore size of the molecular sieve in step (2) is replaced with 30 nm.

[0061] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0062] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 7–18 nm.

[0063] Example 4

[0064] The preparation process is basically the same as in Example 1, except that the pore size of the molecular sieve in step (2) is replaced with 50 nm.

[0065] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0066] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 12–30 nm.

[0067] Comparative Example 1

[0068] The preparation process is basically the same as in Example 1, except that in step (2), nitrogen gas (without passing through a molecular sieve) is directly introduced into the reactor.

[0069] The BET, pore volume, pore size, and pore size distribution data of the carbon materials prepared in this comparative example are listed in Table 1 below.

[0070] Example 5

[0071] The preparation process is basically the same as in Example 1, except that:

[0072] In step (2), the flow rate of the introduced nano gas is replaced with 10 L / min, the introduction time is replaced with 40 min, and the pressure inside the reaction is controlled to be 7 MPa.

[0073] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0074] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 2.5 to 9.0 nm.

[0075] Example 6

[0076] The preparation process is basically the same as in Example 1, except that:

[0077] In step (2), the flow rate of the introduced nano gas is replaced with 20 L / min, the introduction time is replaced with 25 min, and the pressure inside the reaction is controlled to be 9 MPa.

[0078] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0079] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 3–9 nm.

[0080] Comparative Example 2

[0081] The preparation process is basically the same as in Example 1, except that:

[0082] In step (2), the flow rate of the introduced nano gas is replaced with 30 L / min and the introduction time is replaced with 15 min.

[0083] The BET, pore volume, pore size, and pore size distribution data of the porous carbon materials prepared in this comparative example are listed in Table 1 below.

[0084] Figure 3 The figure shows the pore size distribution curve of the porous carbon material prepared in this comparative example. Observing this figure, it can be found that there are multiple peaks and the pore size distribution is not concentrated.

[0085] The presence of multiple peaks in porous carbon materials has an adverse effect on practical applications. Taking applications in the fields of biomedicine and electrochemistry as examples, a uniform pore structure can make the encapsulated material evenly dispersed in the internal pores. If the pore size is uneven, the encapsulated material is prone to internal agglomeration during loading and unloading, which can block the channels and affect the overall efficiency of the material.

[0086] Comparative Example 3

[0087] The preparation process is basically the same as in Example 1, except that:

[0088] In step (2), the flow rate of the introduced nano gas is replaced with 5 L / min and the introduction time is replaced with 90 min.

[0089] The BET, pore volume, pore size, and pore size distribution data of the porous carbon materials prepared in this comparative example are listed in Table 1 below.

[0090] Figure 4 The diagram shows the pore size distribution of the porous carbon material prepared in this comparative example. Observing this diagram, it can also be seen that there are multiple peaks and the pore size distribution is not concentrated.

[0091] Comparative Example 4

[0092] The preparation process is basically the same as in Example 1, except that:

[0093] In step (2), the flow rate of the introduced nano-gas is changed to 20 L / min, the introduction time is changed to 40 min, and the pressure inside the reaction is controlled at 15 MPa.

[0094] The BET, pore volume, pore size, and pore size distribution data of the porous carbon materials prepared in this comparative example are listed in Table 1 below.

[0095] Tests showed that the pore size of the porous carbon material prepared in this comparative example was concentrated in the range of 3–10 nm.

[0096] Figure 5 The image shows a TEM image of the porous carbon material prepared in this comparative example. As can be seen from the image, the pores inside the porous carbon material prepared under this process condition show obvious collapse. Compared with the porous carbon material prepared in Example 1, the specific surface area and pore volume have decreased significantly, and the morphology of this collapse is not conducive to subsequent practical applications.

[0097] Comparative Example 5

[0098] The preparation process is basically the same as in Example 1, except that:

[0099] In step (2), the flow rate of the introduced nano gas is 10 L / min, the introduction time is replaced with 25 min, and the pressure inside the reaction is controlled to be 4 MPa.

[0100] The BET, pore volume, pore size, and pore size distribution data of the porous carbon materials prepared in this comparative example are listed in Table 1 below.

[0101] Tests showed that the pore size of the porous carbon material prepared in this comparative example was concentrated in the range of 2.5–8 nm.

[0102] Figure 6The image shows a TEM image of the porous carbon material prepared in this comparative example. As can be seen from the image, the porous carbon material prepared under this process condition has more pores on its surface and significantly fewer internal pore structures. Compared with the porous carbon material prepared in Example 1, the specific surface area and pore volume have decreased significantly, and this morphology is not conducive to its subsequent practical application.

[0103] Example 7

[0104] The preparation process is basically the same as in Example 1, except that nitrogen in step (2) is replaced with water vapor.

[0105] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0106] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 1.5 to 10 nm.

[0107] Example 8

[0108] The preparation process is basically the same as in Example 1, except that nitrogen in step (2) is replaced with carbon dioxide.

[0109] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0110] Tests showed that the pore size of the porous carbon material prepared in this embodiment is concentrated in the range of 2–10 nm.

[0111] Example 9

[0112] (1) Add 70% of the volume of petroleum coke powder into the reactor, evacuate the vacuum, and set the program to heat up to 80°C so that the petroleum coke powder gradually softens completely.

[0113] (2) Nitrogen gas is introduced into a molecular sieve with a pore size of 10 nm to form nano gas, which is then introduced into the reactor. The flow rate of the nano gas is 18 L / min and the introduction time is 25 min. Nano bubbles are formed inside the softened petroleum coke, and the pressure inside the reactor is controlled to be 8 MPa.

[0114] (3) The reactor is programmed to heat up to 140°C and held for 8 hours. After the holding time is completed, the pressure is released and nitrogen is introduced. After cooling to room temperature, the material is taken out to obtain blocky porous petroleum coke material.

[0115] (4) Crush the blocky porous petroleum coke material so that the particle size of the crushed material is controlled between 2 and 10 μm. Then put the crushed material into a carbonization furnace and heat it to 550°C under a nitrogen atmosphere for 4 hours until it is completely carbonized. After cooling to room temperature, it is taken out to obtain porous carbon material.

[0116] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0117] Figure 7 The adsorption-desorption isotherm of the porous carbon material prepared in this embodiment is based on... Figure 5 It can be seen that the curve has the characteristics of a type I isotherm curve, indicating that the porous carbon material prepared in this embodiment has micropores and relatively narrow mesopores.

[0118] Figure 8 The pore size distribution curve of the porous carbon material prepared in this embodiment is based on... Figure 2 It can be seen that its pore size is concentrated in the range of 3 to 9 nm.

[0119] Example 10

[0120] (1) Add coal tar powder accounting for 70% of the volume of the reactor into the reactor, evacuate the vacuum, and set the program to heat up to 75°C so that the coal tar powder gradually softens completely.

[0121] (2) Nitrogen gas is introduced into a molecular sieve with a pore size of 10 nm to form nano gas, which is then introduced into the reactor. The flow rate of the nano gas is 18 L / min and the introduction time is 25 min. Nano bubbles are formed inside the softened asphalt, and the pressure inside the reactor is controlled to be 8 MPa.

[0122] (3) The reactor is set to heat up to 155°C and the heat is held for 7 hours. After the heat holding is completed, the pressure is released and nitrogen is introduced. After cooling to room temperature, the material is taken out and a blocky porous asphalt material is obtained.

[0123] (4) Crush the blocky porous asphalt material so that the particle size of the crushed material is controlled between 2 and 10 μm. Then put the crushed material into a carbonization furnace and heat it to 800°C under a nitrogen atmosphere for 4 hours until it is completely carbonized. After cooling to room temperature, it is taken out to obtain porous carbon material.

[0124] The BET, pore volume, pore size, and pore size distribution data of the porous carbon material prepared in this embodiment are listed in Table 1 below.

[0125] Figure 9 The adsorption-desorption isotherm of the porous carbon material prepared in this embodiment is based on... Figure 6 It can be seen that the curve has the characteristics of a type I isotherm curve, indicating that the porous carbon material prepared in this embodiment has micropores and relatively narrow mesopores.

[0126] Figure 10 The pore size distribution curve of the porous carbon material prepared in this embodiment is based on... Figure 2 It can be seen that its pore size is concentrated in the range of 3 to 8 nm.

[0127] Table 1

[0128]

[0129]

[0130] The above-described embodiments are preferred embodiments, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A method for preparing porous carbon materials, characterized in that, Includes the following steps: (1) The organic carbon source is put into the reactor, and after evacuation, the temperature is raised to the softening point of the organic carbon source. (2) After the gas is introduced into the molecular sieve, nano gas is formed. The nano gas is introduced into the reactor to form nano bubbles inside the softened organic carbon source, and the pressure inside the reactor is controlled to reach a predetermined pressure. The gas is selected from one or more of nitrogen, carbon monoxide, carbon dioxide, water vapor, and inert gases; The molecular sieve has a pore size of 3~50 nm; The flow rate of the nano-gas introduced is 8~22L / min, the introduction time is 25~80min, and the internal pressure of the reactor is controlled at 5~12MPa; (3) Continue heating to 50°C above the softening point of the organic carbon source, keep it at that temperature for a period of time, and then cool it to room temperature to obtain a porous material. Then, carbonize the porous carbon material.

2. The method for preparing porous carbon materials according to claim 1, characterized in that, In step (1): The organic carbon source is selected from one or more of the following: high molecular polymers, coal and coal derivatives, and petroleum and petroleum derivatives. The amount of organic carbon source added accounts for 10-90% of the reactor volume.

3. The method for preparing porous carbon materials according to claim 1, characterized in that, In step (3): Continue heating to 60-100℃ above the softening point of the organic carbon source, and hold for 1-10 hours; The carbonization process is carried out under an inert atmosphere at a temperature of 550~950℃.

4. The method for preparing porous carbon materials according to claim 1, characterized in that, In step (3): The porous material is first crushed to a particle size of 2~10μm and then carbonized.

5. The method for preparing porous carbon materials according to any one of claims 1 to 4, characterized in that: The flow rate of the nano-gas introduced is 10~20L / min, the introduction time is 25~40min, and the internal pressure of the reactor is controlled at 7~9MPa.

6. The method for preparing porous carbon materials according to claim 5, characterized in that: The molecular sieve has a pore size of 3~10 nm; The gas is selected from carbon dioxide and / or water vapor.

7. A porous carbon material prepared by the method according to any one of claims 1 to 6.

8. An application of the porous carbon material according to claim 7 in the fields of electrochemistry, adsorption catalysis, and biomedicine.

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