Preparation of phenolic resin-based porous carbon and its application in gas separation field
By adjusting the solvent ratio and pyrolysis process in the polymerization reaction of phenolic resin, a porous carbon material with uniform pore size, low cost and environmental friendliness was prepared. This solved the problems of difficult pore size adjustment and complicated preparation of phenolic resin-based porous carbon materials in the prior art, and achieved a highly efficient methane/nitrogen separation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2026-03-26
- Publication Date
- 2026-06-26
AI Technical Summary
Existing phenolic resin-based porous carbon materials are difficult to adjust in terms of pore size in the field of gas adsorption and separation, and their preparation process is complex, costly, and causes serious environmental pollution, making it difficult to meet the development needs of green chemistry.
By adjusting the solvent ratio in the polymerization reaction of phenolic resin, carbon precursor phenolic resins with different degrees of crosslinking were prepared. The pore size was adjusted by using the pyrolysis process, avoiding the use of activators, and porous carbon materials with uniform pore size were obtained by direct carbonization.
This study simplifies the preparation process, reduces costs, and provides an environmentally friendly porous carbon material suitable for methane/nitrogen separation, exhibiting uniform pore size distribution and excellent adsorption performance.
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Figure CN122276708A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of porous carbon materials, and in particular to a method for preparing porous carbon suitable for the adsorption and separation of methane / nitrogen. Background Technology
[0002] Phenolic resin-based carbon materials have wide applications in activated carbon preparation, catalyst supports, and supercapacitor electrode materials due to their excellent electrical conductivity and chemical stability. In the field of gas adsorption and separation, phenolic resin-based porous carbon has been extensively studied due to its advantages of self-forming, high strength, and high carbon yield.
[0003] For porous carbon materials used in gas adsorption and separation, uniform micropore size and high micropore volume are crucial. Existing phenolic resin-based porous carbons and other porous carbons used in gas adsorption and separation suffer from difficulties in pore size adjustment and non-uniformity. The pore size adjustment mechanism of traditional metal ion activation methods has been revealed by researchers and applied to guide the production process of adsorbent materials; however, the production cost is high, and it is highly corrosive to carbonization equipment, requiring acid washing post-treatment and generating waste acid and waste gas, which is inconsistent with the development concept of green chemistry. For example, Chinese patent CN118183733A involves pre-carbonizing the carbon precursor, then mixing it with an activator and performing high-temperature activation, followed by acid washing to obtain the porous carbon material. This process is not only cumbersome but also consumes a lot of energy and generates waste acid and metal waste liquid. Although existing technologies use in-situ ion activation or metal-organic frameworks (MOFs) to disperse metal ions as much as possible and reduce the amount of metal used to achieve the best pore-forming effect, the process is extremely complex. As described in Chinese Patent CN118649686B, the desired porous carbon is obtained through a multi-step design and operation process.
[0004] In addition, some existing methods for preparing phenolic resin-based porous carbon do not require activators, but require multiple processing steps. For example, a hydrothermal reaction or chemical modification with strong acids and bases is carried out first, and then the pore size of a specific precursor is created in advance to obtain the required pore size. Then, the pre-designed pore structure is inherited during the carbonization process. The process is extremely cumbersome and has poor process repeatability. Summary of the Invention
[0005] Therefore, it is necessary to improve the existing technology and provide a method for preparing phenolic resin-based porous carbon with good repeatability, simple process and low cost.
[0006] To achieve the above objectives, the present invention adopts the following technical solution.
[0007] A method for preparing phenolic resin-based porous carbon is achieved through the following steps:
[0008] (1) Preparation of carbon precursor phenolic resin:
[0009] Phenol and aldehyde in a molar ratio of 1:1.2~2 are dissolved in an alcohol-water mixture, wherein the volume ratio of alcohol to water in the alcohol-water mixture is 7:1~10. Then, an appropriate amount of catalyst inorganic acid is added dropwise under an ice-water bath. After the addition is complete, the mixture is stirred evenly. Then, the reaction system is placed at 60~100 °C for polymerization. After the reaction is completed, the product is dried to obtain carbon precursor phenolic resin.
[0010] (2) Preparation of phenolic resin-based porous carbon:
[0011] The carbon precursor phenolic resin is placed in a tube furnace and heated under an inert atmosphere at a heating rate not exceeding 10 °C / min. The temperature is maintained at 800-1000 °C for 2 h to obtain phenolic resin-based porous carbon. The pore size of the phenolic resin-based porous carbon prepared by the method of the present invention is concentrated in the range of 0.5~0.9 nm, and accounts for more than 95% of its porous structure.
[0012] According to the definition of the International Union of Pure and Applied Chemistry (IUPAC), in porous materials, micropores are defined as having a pore size less than 2 nm, macropores as having a pore size greater than 50 nm, and mesopores as having a pore size between micropores and macropores, i.e., a pore size of 2-50 nm. The phenolic resin-based porous carbon prepared by the method of this invention has a pore size not exceeding 3 nm, with micropores accounting for more than 95% of the structure, specifically those between 0.5 and 0.9 nm.
[0013] Preferably, the phenol includes at least one selected from phenol, resorcinol, pyrogallol, hydroquinone, cresol, and xylenol. More preferably, the phenol is resorcinol and phenol.
[0014] Preferably, the aldehyde includes at least one selected from formaldehyde, furfural, terephthalaldehyde, and acetaldehyde. More preferably, the aldehyde is furfural or terephthalaldehyde.
[0015] Preferably, the alcoholic organic solvent includes at least one of methanol, ethanol, and propanol.
[0016] Preferably, the catalyst is any one of hydrochloric acid, sulfuric acid, or nitric acid. More preferably, the acid in the catalyst is hydrochloric acid.
[0017] Preferably, the drying method includes any one of vacuum drying, forced air drying, and freeze drying.
[0018] Preferably, the inert atmosphere is any one of nitrogen, argon, or helium.
[0019] Preferably, the heating rate is 5 °C / min, and the temperature is maintained between 800 °C and 1000 °C for 2 hours.
[0020] The phenolic resin-based porous carbon obtained by the method of this invention is suitable for the field of gas separation, especially for the separation of CH4 / N2 mixed gases.
[0021] In the preparation method of phenolic resin-based porous carbon of the present invention, the carbon precursor phenolic resin with different degrees of crosslinking polymerization is prepared by adjusting the solvent ratio in the reaction system. Phenolic resins with different degrees of crosslinking polymerization exhibit different thermal decomposition behaviors during pyrolysis. Phenolic resins with low crosslinking degree have lower thermal stability and relatively more volatile components, resulting in fully developed pores and porous carbon with larger pore sizes; phenolic resins with high crosslinking degree yield porous carbon with smaller pore sizes. Therefore, according to actual needs, the phenolic resin-based porous carbon prepared by the present invention has suitable micropore size and a very high micropore ratio, exhibiting excellent adsorption and separation performance for CH4 / N2. This method does not require any activating reagents and does not involve harsh reaction and carbonization conditions, achieving efficient adsorption and separation of methane / nitrogen by phenolic resin-based porous carbon.
[0022] This invention, based on the characteristics of the phenolic resin polymerization process, uses a specific solvent as a carrier for the phenolic resin polymerization reaction, thereby obtaining carbon precursor phenolic resins with different degrees of cross-linking polymerization. During carbonization, phenolic resins with a high degree of cross-linking exhibit higher thermal stability, and their three-dimensional cross-linking network is difficult to destroy. Therefore, they release less oxygen-containing gas, resulting in incomplete pore development and smaller pore sizes. Secondly, the presence of the three-dimensional cross-linking network causes defects caused by carbon loss to occur in concentrated areas, and these defects imply localized overdevelopment of the pore size, ultimately leading to pore size inhomogeneity. However, for phenolic resins with a lower degree of cross-linking, the lower thermal stability leads to the release of a large amount of oxygen-containing gas, resulting in larger pore sizes. Furthermore, due to the relative independence of the phenolic resin chains, the carbon defect positions are uniform, naturally resulting in more uniform pore sizes.
[0023] Therefore, compared with the prior art, the present invention has the following beneficial technical effects:
[0024] (1) The method for preparing phenolic resin-based porous carbon of the present invention relies solely on the structural characteristics of the carbon precursor itself to prepare phenolic resin-based porous carbon with a suitable pore size for methane / nitrogen separation scenarios. The operation is simple, the repeatability is good, and the preparation process of porous carbon is greatly simplified.
[0025] (2) The preparation method of phenolic resin-based porous carbon of the present invention greatly reduces the production cost of porous carbon. The pore size adjustment method is green and safe, and has no pollution to the environment and no harm to the human body. Attached Figure Description
[0026] Figure 1 This is a pore size distribution diagram for Example 1.
[0027] Figure 2 The graph shows the gas separation performance of methane and nitrogen in Example 1.
[0028] Figure 3 The diagram shows the gas separation performance of methane and nitrogen in Example 2.
[0029] Figure 4 The diagram shows the gas separation performance of methane and nitrogen in Example 3.
[0030] Figure 5 The graph shows the gas separation performance of methane / nitrogen in Example 4.
[0031] Figure 6 The diagram shows the gas separation performance of methane and nitrogen in Example 5. Detailed Implementation
[0032] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.
[0033] Example 1
[0034] 1 g of resorcinol and 1.5 ml of furfural were dissolved in a mixed solution of methanol and water (methanol:water = 7:1). 0.3 mL of hydrochloric acid catalyst was added while stirring in an ice-water bath. After thorough mixing, the reaction system was sealed and placed in an oven at 60 °C for curing, and then dried at the same temperature for 24 h to obtain phenolic resin. The obtained phenolic resin was then placed in a tube furnace and heated to 800 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h to obtain phenolic resin-based porous carbon.
[0035] Figure 1 This is a pore size distribution diagram of the porous carbon product obtained in Example 1. Figure 1 It can be seen that the pore size of the obtained phenolic resin-based porous carbon is concentrated at 0.60 nm, and there is a small amount of pore size distribution of 2.5 nm in the porous carbon structure.
[0036] The aforementioned porous carbon products demonstrate gas separation performance for methane and nitrogen, as shown in [link to relevant documentation]. Figure 2 .Depend on Figure 2 It can be seen that the equilibrium adsorption capacity of this porous carbon product for methane is 15.6 cm⁻¹. 3 / g, the equilibrium adsorption capacity of nitrogen is 3.08 cm⁻¹. 3 / g can effectively separate methane / nitrogen.
[0037] Example 2
[0038] 1 g of resorcinol and 1.5 ml of furfural were dissolved in a mixed solution of methanol and water (methanol:water = 7:3). 0.3 mL of hydrochloric acid catalyst was added while stirring in an ice-water bath. After thorough mixing, the reaction system was sealed and placed in an oven at 80 °C for curing, followed by drying at the same temperature for 24 h to obtain phenolic resin. The obtained phenolic resin was then placed in a tube furnace and heated to 1000 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h to obtain phenolic resin-based porous carbon.
[0039] Upon testing, the pore size of the phenolic resin-based porous carbon obtained in this embodiment is concentrated at 0.69 nm, and there are pore size distributions of 1.2 nm and 2 nm in the porous carbon structure. The pore size distribution diagram of the product is basically similar to that of Example 1, and will not be repeated here.
[0040] The aforementioned porous carbon products demonstrate gas separation performance for methane and nitrogen, as shown in [link to relevant documentation]. Figure 3 .Depend on Figure 3 It can be seen that the equilibrium adsorption capacity of the obtained phenolic resin-based porous carbon for methane is 20.8 cm⁻¹. 3 / g, the equilibrium adsorption capacity of nitrogen is 7.9 cm⁻¹. 3 / g can effectively separate methane / nitrogen.
[0041] Example 3
[0042] 1 g of resorcinol and 1.5 ml of furfural were dissolved in a mixed solution of methanol and water (methanol:water = 7:5). 0.3 mL of hydrochloric acid catalyst was added while stirring in an ice-water bath. After thorough mixing, the reaction system was sealed and placed in an oven at 60 °C for curing, followed by drying at the same temperature for 24 h to obtain phenolic resin. The obtained phenolic resin was then placed in a tube furnace and heated to 1000 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h to obtain phenolic resin-based porous carbon.
[0043] Upon testing, the pore size of the phenolic resin-based porous carbon obtained in this embodiment is 0.8 nm, and there is a pore size distribution of 2.0 nm in the porous carbon structure. The pore size distribution diagram of the product is basically similar to that of Example 1, and will not be repeated here.
[0044] The aforementioned porous carbon products demonstrate gas separation performance for methane and nitrogen, as shown in [link to relevant documentation]. Figure 4 .Depend on Figure 4 It can be seen that the equilibrium adsorption capacity of the obtained phenolic resin-based porous carbon for methane is 22.9 cm⁻¹. 3 / g, the equilibrium adsorption capacity of nitrogen is 7.6 cm⁻¹. 3 / g can effectively separate methane / nitrogen.
[0045] Example 4
[0046] 1 g of resorcinol and 1.5 ml of furfural were dissolved in a mixed solution of methanol and water (methanol:water = 7:7). 0.3 mL of hydrochloric acid catalyst was added while stirring in an ice-water bath. After thorough mixing, the reaction system was sealed and placed in an oven at 60 °C for curing, followed by drying at the same temperature for 24 h to obtain phenolic resin. The obtained phenolic resin was then placed in a tube furnace and heated to 1000 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h to obtain phenolic resin-based porous carbon.
[0047] Testing revealed that the pore size of the phenolic resin-based porous carbon obtained in this embodiment is concentrated at 0.82 nm, with a pore size distribution of 1.9 nm present in the porous carbon structure. The pore size distribution diagram of the product is basically similar to that of Example 1, and will not be repeated here. The gas separation performance of the aforementioned porous carbon product for methane and nitrogen is shown in [reference needed]. Figure 5 .Depend on Figure 5 It can be seen that the equilibrium adsorption capacity for methane is 24.3 cm⁻¹. 3 / g, the equilibrium adsorption capacity of nitrogen is 8.4 cm⁻¹. 3 / g can effectively separate methane / nitrogen.
[0048] Example 5
[0049] 1 g of resorcinol and 1.5 ml of furfural were dissolved in a mixed solution of methanol and water (methanol:water = 7:9). 0.3 mL of hydrochloric acid catalyst was added while stirring in an ice-water bath. After thorough mixing, the reaction system was sealed and placed in an oven at 60 °C for curing, followed by drying at the same temperature for 24 h to obtain phenolic resin. The obtained phenolic resin was then placed in a tube furnace and heated to 1000 °C at a heating rate of 5 °C / min, and held at this temperature for 2 h to obtain phenolic resin-based porous carbon.
[0050] Upon testing, the pore size of the phenolic resin-based porous carbon obtained in this embodiment is concentrated at 0.89 nm. The pore size distribution diagram of the product is basically similar to that of Example 1, and will not be repeated here.
[0051] The aforementioned porous carbon products demonstrate gas separation performance for methane and nitrogen, as shown in [link to relevant documentation]. Figure 6 .Depend on Figure 6 It can be seen that the equilibrium adsorption capacity for methane is 36.6 cm⁻¹. 3 / g, the equilibrium adsorption capacity of nitrogen is 11.5 cm⁻¹. 3 / g can effectively separate methane / nitrogen.
[0052] The preparation and performance of the phenolic resin-based porous carbon of the present invention have been described in detail in the above embodiments. Based on the present invention, some modifications or improvements can be made, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. A method for preparing phenolic resin-based porous carbon, characterized in that, Includes the following steps: (1) Preparation of carbon precursor phenolic resin Phenol and aldehyde in a molar ratio of 1:1.2~2 are dissolved in an alcohol-water mixed solution, wherein the volume ratio of alcohol to water in the alcohol-water mixed solution is 7:1~10. An inorganic acid catalyst of a certain concentration is added dropwise while stirring in an ice-water bath. After the addition is complete, the reaction system is sealed and placed at 60-100 °C for polymerization. After the reaction is completed, the product is dried to obtain carbon precursor phenolic resin. (2) Preparation of phenolic resin-based porous carbon The carbon precursor phenolic resin was placed in a tube furnace and heated at a heating rate of 5 ℃ / min at a heating rate of no more than 10 ℃ / min under an inert atmosphere. The mixture was then held at 800-1000 ℃ for 2 h to obtain phenolic resin-based porous carbon. The pore size of the phenolic resin-based porous carbon was less than 3 nm, and the proportion of micropores between 0.5 and 0.9 nm was ≥95%.
2. The method for preparing carbon precursor phenolic resin according to claim 1, characterized in that, The phenols mentioned include at least one of aromatic phenols such as phenol, resorcinol, pyrogallol, hydroquinone, cresol, and xylenol.
3. The method for preparing carbon precursor phenolic resin according to claim 1, characterized in that, The aldehydes include at least one or more of formaldehyde, furfural, terephthalaldehyde, and acetaldehyde.
4. The method for preparing carbon precursor phenolic resin according to claim 1, characterized in that, The organic solvent includes at least one of methanol, ethanol, and propanol.
5. The method for preparing carbon precursor phenolic resin according to claim 1, characterized in that, The catalyst is any one of hydrochloric acid, sulfuric acid, or nitric acid.
6. The method for preparing carbon precursor phenolic resin according to claim 1, characterized in that, The drying method includes any one of the following: vacuum drying, forced air drying, and freeze drying.
7. The method for preparing phenolic resin-based porous carbon according to claim 1, characterized in that, The inert atmosphere is any one of nitrogen, argon or helium.
8. The method for preparing phenolic resin-based porous carbon according to claim 1, characterized in that, The heating rate was 5℃ / min, and the temperature was maintained between 800℃ and 1000℃ for 2 hours.
9. A phenolic resin-based porous carbon obtained by the preparation method according to any one of claims 1-8.
10. An application of the phenolic resin-based porous carbon according to claim 9 in the field of gas separation.