Nitrogen-doped phenolic resin-based carbon adsorbent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of preparation of carbon adsorption materials, and discloses a nitrogen-doped phenolic resin-based carbon adsorbent as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing ammonia water, absolute ethyl alcohol, resorcinol and water to obtain an alkaline resorcinol solution; the method comprises the following steps: mixing an alkaline resorcinol solution with formaldehyde to obtain a resorcinol formaldehyde resin suspension; and mixing the resorcinol formaldehyde resin suspension and the aminopyrimidine solution, and sequentially carrying out hydro-thermal treatment and thermal treatment to obtain the nitrogen-doped phenolic resin-based carbon adsorbent. The nitrogen-doped phenolic resin-based carbon adsorbent obtained by the invention enhances the separation effect of CH4 / N2 and CO2 / CH4.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon adsorption material preparation, and in particular to a nitrogen-doped phenolic resin-based carbon adsorbent and a preparation method and application thereof. Background Art

[0002] Natural gas includes methane, nitrogen and carbon dioxide, among which methane is the main component of natural gas, which makes it considered a renewable clean energy. According to the different methane concentrations, natural gas with a methane concentration higher than 70% is called high-concentration natural gas, which can be used directly; natural gas with a methane concentration lower than 30% is called low-concentration natural gas, which cannot be used directly due to its high nitrogen content. Therefore, it is very important to enrich methane in low-concentration natural gas to achieve efficient energy utilization. In addition, carbon dioxide is a major greenhouse gas. Due to the rapid development of industry, many serious climate problems have been caused. The large-scale emission of carbon dioxide is an important source of these problems, so it is also very important to capture carbon dioxide.

[0003] At present, the main gas separation processes include cryogenic distillation, hydrate method, adsorption method, etc. Cryogenic distillation has high requirements for equipment, high energy consumption and complex operation. The hydrate method is immature in technology, and the hydrate formation rate is low, and the number of promoters that promote hydrate formation is relatively small. The adsorption method has the advantages of mature technology, large operational flexibility, low energy consumption and low cost. The core of the adsorption method is the development of selective adsorbents. Currently, the commonly used adsorbents are mainly zeolites, metal organic frameworks (MOFs) and porous carbon materials. Zeolites are usually used in alkane and olefin separation systems, and their adsorption capacity for methane, nitrogen and carbon dioxide is low, and they are not suitable for CH 4 / N 2 / CO 2 The preparation process of MOFs is complex, the preparation cost is high, and it is not easy to industrialize. Porous carbon materials are widely used in the field of adsorption separation because of their wide sources, easy production, designable structure and controllable surface properties. Porous carbon materials have a high affinity for carbon dioxide and CH 4 / N 2 The system also has good separation performance. According to the different sources of carbon material precursors, there are mainly coal-based carbon, biomass carbon, and phenolic resin-based carbon. Among them, the porous carbon material prepared with phenolic resin as a precursor has the advantages of designable structure and adjustable surface properties. According to different separation systems, the physical and chemical properties of carbon materials can be adjusted to enhance their selectivity, thereby improving separation efficiency.

[0004] Due to CO 2 (0.330nm), CH 4 (0.380nm), N2 (0.364nm) is different from the kinetic diameter, so it is necessary to regulate the pore structure of phenolic resin-based carbon to enhance the separation effect. Currently, the commonly used regulation methods include heteroatom doping, activation method and metal modification method. The activation method usually uses an activator to react with the structure of the carbon material to regulate it. Commonly used activators are potassium hydroxide and potassium carbonate, but other ions will be introduced into the carbon material, resulting in a decrease in the separation effect. The metal modification method uses a metal ion impregnation method to regulate the pores of the carbon material, but this method will block some open pores into closed pores, thereby reducing the adsorption site and the adsorption amount. Heteroatom doping mainly involves adding a carbon source containing heteroatoms to the precursor, thereby doping heteroatoms in the carbon material structure. Commonly used heteroatom doping is mainly nitrogen atom doping, which is divided into amino nitrogen and heterocyclic nitrogen according to the different forms of the nitrogen source. Among them, amino nitrogen will become ammonia gas after high-temperature carbonization after doping, and it is difficult to leave nitrogen in the carbon structure; while heterocyclic nitrogen has a stable structure because the nitrogen atom exists on the ring, and it is not easy to decompose after high-temperature carbonization.

[0005] Therefore, it is of great significance to study a nitrogen-doped phenolic resin-based carbon adsorbent that can efficiently separate methane / nitrogen and methane / carbon dioxide, as well as its preparation method and application. Summary of the invention

[0006] In view of this, the present invention provides a nitrogen-doped phenolic resin-based carbon adsorbent and a preparation method and application thereof, the purpose of which is to solve the technical problem of low separation efficiency of the carbon adsorbent prepared in the prior art.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] The present invention provides a method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent, comprising the following steps:

[0009] 1) mixing ammonia water, anhydrous ethanol, resorcinol and water to obtain an alkaline resorcinol solution;

[0010] 2) mixing the alkaline resorcinol solution with formaldehyde to obtain a resorcinol formaldehyde resin suspension;

[0011] 3) The resorcinol formaldehyde resin suspension is mixed with the aminopyrimidine solution and then subjected to hydrothermal treatment and heat treatment in sequence to obtain a nitrogen-doped phenolic resin-based carbon adsorbent.

[0012] Preferably, in step 1), the ratio of ammonia water, anhydrous ethanol, resorcinol and water is 0.3-0.8 mL: 25-45 mL: 4-6 g: 40-80 mL;

[0013] The mixing time is 1 to 3 hours, and the mixing speed is 300 to 500 rpm.

[0014] Preferably, in step 2), the dosage ratio of formaldehyde to resorcinol is 5-15 mL:4-6 g;

[0015] The mixing speed is 300-500 rpm, and the mixing time is 6-8 hours.

[0016] Preferably, in step 3), the aminopyrimidine solution is obtained by mixing ammonia water, anhydrous ethanol, water, formaldehyde and aminopyrimidine;

[0017] The aminopyrimidine is a mixed solution of 2,4,6-triaminopyrimidine and melamine or 2,4,6-triaminopyrimidine;

[0018] When the aminopyrimidine is a mixed solution of 2,4,6-triaminopyrimidine and melamine, the mass ratio of 2,4,6-triaminopyrimidine to melamine is 0.8-1.2:0.8-1.2.

[0019] Preferably, the dosage ratio of the ammonia water, anhydrous ethanol, water, formaldehyde and aminopyrimidine is 0.1-0.3 mL: 10-15 mL: 18-22 mL: 3-5 mL: 1.1-1.2 g;

[0020] The mixing time is 20 to 70 minutes, and the mixing temperature is 20 to 30°C.

[0021] Preferably, in step 3), the mixing time is 50 to 70 minutes;

[0022] The volume ratio of the resorcinol formaldehyde resin suspension to the aminopyrimidine solution is 65-130:30-45.

[0023] Preferably, in step 3), the temperature of the hydrothermal treatment is 100 to 150° C., and the time of the hydrothermal treatment is 20 to 26 hours.

[0024] Preferably, in step 3), the heat treatment includes a first stage heat treatment and a second stage heat treatment;

[0025] In the first stage of heat treatment, the heating rate is 1-3°C / min, the heat treatment temperature is 180-220°C, and the heat treatment time is 40-70min;

[0026] In the second stage of heat treatment, the heating rate is 1-3°C / min, the heat treatment temperature is 750-850°C, and the heat treatment time is 3-5h.

[0027] The present invention also provides a nitrogen-doped phenolic resin-based carbon adsorbent prepared by a method for preparing the nitrogen-doped phenolic resin-based carbon adsorbent.

[0028] The present invention also provides application of the nitrogen-doped phenolic resin-based carbon adsorbent in the field of gas separation.

[0029] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0030] The nitrogen-doped phenolic resin-based carbon adsorbent of the present invention adds aminopyrimidine during preparation to enhance the methane enrichment effect and increase the carbon dioxide adsorption capacity; the adsorption capacity for methane is enhanced, and although the adsorption capacity for nitrogen is also improved, the overall methane adsorption capacity is large, and the adsorption capacity for carbon dioxide is greatly enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 are compared with CH 4 / N 2 Separation ratio diagram;

[0033] Figure 2 The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 are compared with the CO 2 / CH 4 Separation ratio diagram;

[0034] Figure 3 The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 are compared with N 2 Adsorption isotherm diagram of

[0035] Figure 4 The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 are compared with CH 4 Adsorption isotherm diagram of

[0036] Figure 5 The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 are compared with the CO 2 Adsorption isotherm diagram. DETAILED DESCRIPTION

[0037] The present invention provides a method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent, comprising the following steps:

[0038] 1) mixing ammonia water, anhydrous ethanol, resorcinol and water to obtain an alkaline resorcinol solution;

[0039] 2) mixing the alkaline resorcinol solution with formaldehyde to obtain a resorcinol formaldehyde resin suspension;

[0040] 3) The resorcinol formaldehyde resin suspension is mixed with the aminopyrimidine solution and then subjected to hydrothermal treatment and heat treatment in sequence to obtain a nitrogen-doped phenolic resin-based carbon adsorbent.

[0041] In the present invention, in the step 1), the dosage ratio of ammonia water, anhydrous ethanol, resorcinol and water is preferably 0.3-0.8 mL: 25-45 mL: 4-6 g: 40-80 mL, more preferably 0.4-0.7 mL: 28-40 mL: 4-6 g: 45-75 mL, and more preferably 0.5-0.6 mL: 30-35 mL: 5 g: 50-60 mL;

[0042] The mixing time is preferably 1 to 3 hours, more preferably 1.5 to 2.5 hours, and more preferably 2 hours. The mixing rotation speed is preferably 300 to 500 rpm, more preferably 350 to 450 rpm, and more preferably 400 to 420 rpm.

[0043] In the present invention, in the step 2), the dosage ratio of formaldehyde to resorcinol is preferably 5-15 mL:4-6 g, more preferably 6-12 mL:4-6 g, and more preferably 7-10 mL:5 g;

[0044] The mixing speed is preferably 300-500 rpm, more preferably 350-450 rpm, more preferably 400-420 rpm, and the mixing time is preferably 6-8 h, more preferably 6.5-7.5 h, more preferably 7 h; the alkaline resorcinol solution is mixed with formaldehyde for polymerization reaction.

[0045] In the present invention, in the step 3), the aminopyrimidine solution is obtained by mixing ammonia water, anhydrous ethanol, water, formaldehyde and aminopyrimidine;

[0046] The aminopyrimidine is preferably a mixed solution of 2,4,6-triaminopyrimidine and melamine or 2,4,6-triaminopyrimidine;

[0047] When the aminopyrimidine is a mixed solution of 2,4,6-triaminopyrimidine and melamine, the mass ratio of 2,4,6-triaminopyrimidine to melamine is preferably 0.8-1.2:0.8-1.2, more preferably 0.9-1.1:0.9-1.1, and more preferably 1:1.

[0048] In the present invention, the dosage ratio of ammonia water, anhydrous ethanol, water, formaldehyde and aminopyrimidine is preferably 0.1-0.3 mL: 10-15 mL: 18-22 mL: 3-5 mL: 1.1-1.2 g, more preferably 0.1-0.3 mL: 11-14 mL: 19-21 mL: 3-5 mL: 1.12-1.18 g, more preferably 0.2 mL: 12-13 mL: 20 mL: 4 mL: 1.14-1.16 g;

[0049] The mixing time is preferably 20 to 70 min, more preferably 30 to 60 min, more preferably 40 to 50 min, and the mixing temperature is preferably 20 to 30°C, more preferably 22 to 28°C, more preferably 24 to 26°C.

[0050] In the present invention, in step 3), the mixing time is preferably 50 to 70 min, more preferably 55 to 65 min, and more preferably 60 min;

[0051] The volume ratio of the resorcinol formaldehyde resin suspension to the aminopyrimidine solution is preferably 65-130:30-45, more preferably 70-120:35-40, and even more preferably 80-100:38-39.

[0052] In the present invention, in step 3), the temperature of the hydrothermal treatment is preferably 100-150°C, more preferably 110-140°C, more preferably 120-130°C, and the time of the hydrothermal treatment is preferably 20-26h, more preferably 21-25h, more preferably 22-24h.

[0053] In the present invention, in step 3), the heat treatment preferably includes a first stage heat treatment and a second stage heat treatment;

[0054] In the first stage of heat treatment, the heating rate is preferably 1-3°C / min, more preferably 1.5-2.5°C / min, more preferably 2-2.2°C / min, the heat treatment temperature is preferably 180-220°C, more preferably 190-210°C, more preferably 200-205°C, and the heat treatment time is preferably 40-70min, more preferably 45-60min, more preferably 50-55min;

[0055] In the second stage heat treatment, the heating rate is preferably 1-3°C / min, more preferably 1.5-2.5°C / min, more preferably 2-2.2°C / min, the heat treatment temperature is preferably 750-850°C, more preferably 770-830°C, more preferably 780-800°C, and the heat treatment time is preferably 3-5h, more preferably 3.5-4.5h, more preferably 4h.

[0056] In the present invention, in the step 3), the heat treatment is preferably carried out under a nitrogen atmosphere, and the flow rate of the nitrogen is preferably 50 to 70 mL / min, more preferably 55 to 65 mL / min, and more preferably 60 to 62 mL / min.

[0057] In the present invention, in the step 3), cooling, centrifugation and drying are preferably performed after the hydrothermal treatment; the cooling is preferably natural cooling, and the cooling temperature is preferably 20-30°C, more preferably 22-28°C, and more preferably 25-26°C; the centrifugal speed is preferably 7000-10000rpm, more preferably 7500-9000rpm, more preferably 8000-8500rpm, and the centrifugal time is preferably 3-7min, more preferably 4-6min, and more preferably 5min; the drying temperature is preferably 50-120°C, more preferably 70-100°C, more preferably 80-90°C, and the drying time is preferably 10-15h, more preferably 11-14h, and more preferably 12-13h.

[0058] In the present invention, the concentration of the aqueous ammonia is preferably 24 to 26%, and more preferably 25%.

[0059] The present invention also provides a nitrogen-doped phenolic resin-based carbon adsorbent prepared by a method for preparing the nitrogen-doped phenolic resin-based carbon adsorbent.

[0060] The present invention also provides application of the nitrogen-doped phenolic resin-based carbon adsorbent in the field of gas separation.

[0061] In the present invention, the gas separation is preferably CH 4 / N 2 Separation and CO 2 / CH 4 Separation.

[0062] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0063] Example 1

[0064] Take 0.4 mL of ammonia water (concentration of 25%), 30 mL of anhydrous ethanol, 50 mL of water and 5 g of resorcinol and stir at 400 rpm for 2 h to obtain an alkaline resorcinol solution;

[0065] The obtained alkaline resorcinol solution was subjected to polymerization reaction with 8 mL of formaldehyde at 25° C. and 400 rpm for 6 h to obtain a resorcinol formaldehyde resin suspension;

[0066] 0.2 mL of ammonia water, 12 mL of anhydrous ethanol, 20 mL of water, 4 mL of formaldehyde and 1.137 g of 2,4,6-triaminopyrimidine were mixed at 25° C. for 60 min to obtain a triaminopyrimidine solution;

[0067] The obtained resorcinol formaldehyde resin suspension was mixed with the obtained triaminopyrimidine solution for 60 minutes, and then subjected to a hydrothermal reaction at 120°C for 24 hours. After naturally cooling to 25°C, the mixture was centrifuged at 8000 rpm for 5 minutes. The obtained solid material was dried at 60°C for 12 hours, and then placed in a porcelain boat under a nitrogen atmosphere with a flow rate of 60 mL / min, and heated to 200°C at a heating rate of 2°C / min and kept warm for 1 hour. Then, the mixture was heated to 800°C at a heating rate of 2°C / min and kept warm for 4 hours to obtain 2,4,6-triaminopyrimidine resorcinol formaldehyde resin-based carbon, which was recorded as "TRFC".

[0068] Example 2

[0069] Take 0.4 mL of ammonia water (concentration of 25%), 30 mL of anhydrous ethanol, 50 mL of water and 5 g of resorcinol and stir at 400 rpm for 2 h to obtain an alkaline resorcinol solution;

[0070] The obtained alkaline resorcinol solution was subjected to polymerization reaction with 8 mL of formaldehyde at 25° C. and 400 rpm for 6 h to obtain a resorcinol formaldehyde resin suspension;

[0071] 0.2 mL of ammonia water, 12 mL of anhydrous ethanol, 20 mL of water, 4 mL of formaldehyde, 0.573 g of melamine and 0.563 g of 2,4,6-triaminopyrimidine were mixed at 25° C. for 30 min to obtain a melamine-triaminopyrimidine solution;

[0072] The obtained resorcinol formaldehyde resin suspension was mixed with the obtained melamine triaminopyrimidine solution for 65 minutes, and then subjected to a hydrothermal reaction at 120°C for 24 hours. After naturally cooling to 25°C, the mixture was centrifuged at 8000 rpm for 5 minutes. The obtained solid material was dried at 60°C for 12 hours, and then placed in a porcelain boat under a nitrogen atmosphere with a flow rate of 60 mL / min, heated to 200°C at a heating rate of 2°C / min, and kept warm for 1 hour. Then, the temperature was increased to 800°C at a heating rate of 2°C / min and kept warm for 4 hours to obtain melamine 2,4,6-triaminopyrimidine resorcinol formaldehyde resin-based carbon.

[0073] Comparative Example 1

[0074] 0.6 mL of ammonia water (concentration of 25%), 42 mL of anhydrous ethanol, 70 mL of water and 5 g of resorcinol were stirred at 400 rpm for 2 h to obtain an alkaline resorcinol solution;

[0075] The obtained alkaline resorcinol solution was subjected to polymerization reaction with 12 mL of formaldehyde at 25° C. and 400 rpm for 7 h to obtain a resorcinol formaldehyde resin suspension;

[0076] The obtained resorcinol formaldehyde resin suspension was subjected to a hydrothermal reaction at 120°C for 24 hours, naturally cooled to 25°C, and then centrifuged at 8000 rpm for 5 minutes. The obtained solid material was dried at 60°C for 12 hours, and then placed in a porcelain boat under a nitrogen atmosphere with a flow rate of 60 mL / min, and heated to 200°C at a heating rate of 2°C / min and kept warm for 1 hour, and then heated to 800°C at a heating rate of 2°C / min and kept warm for 4 hours to obtain resorcinol formaldehyde resin-based carbon, recorded as "RFC".

[0077] The adsorption separation performance and carbon dioxide adsorption capacity of the TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 were tested, and the testing steps were as follows:

[0078] Adsorption separation performance test: volumetric method. The test results are shown in Table 1.

[0079] Carbon dioxide adsorption detection: volumetric method. The test results are shown in Table 2.

[0080] Table 1 Separation ratio of TRFC obtained in Example 1 and RFC obtained in Comparative Example 1

[0081]

[0082] The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 have a significant effect on CH 4 / N 2 The separation ratio is shown in Figure Figure 1 As shown, the TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 have a significant effect on CO 2 / CH 4 The separation ratio is shown in Figure Figure 2 As shown. Figures 1-2 From Table 1, we can see that for CH 4 / N 2 The separation ratio of RFC is 2.7 at normal pressure (0.1 MPa), while that of TRFC is 3.7 at normal pressure. The separation ratio of RFC is 1.8 at 0.7 MPa, while that of TRFC is 2.1 at 0.7 MPa. 2 / CH 4 The separation ratio of RFC is 0.77 at normal pressure, while that of TRFC is 2.05 at normal pressure. The separation ratio of RFC is 0.94 at 0.7 MPa, while that of TRFC is 1.63 at 0.7 MPa. This indicates that the nitrogen-doped phenolic resin-based carbon adsorbent obtained by the present invention can significantly improve the CH 4 / N2 , CO 2 / CH 4 separation effect.

[0083] Table 2 The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 react with CO at 0.8 MPa 2 , CH 4 、N 2 Adsorption

[0084]

[0085] The TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 were compared with each other. 2 The adsorption isotherm diagram is shown in Figure 3 As shown, the TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 have a significant effect on CH 4 The adsorption isotherm diagram is shown in Figure 4 As shown, the TRFC obtained in Example 1 and the RFC obtained in Comparative Example 1 have a significant effect on CO 2 The adsorption isotherm diagram is shown in Figure 5 As shown by Figures 3 to 5 From Table 2, we can see that for N 2 The equilibrium adsorption capacity of RFC is 17.8 mL / g, and TRFC is 14.4 mL / g, with a difference of 3.4 mL / g. 4 The equilibrium adsorption capacity of RFC is 32.0 mL / g, and TRFC is 28.9 mL / g, with a difference of 3.1 mL / g. 2 The equilibrium adsorption capacity is 29.9 mL / g for RFC and 46.5 mL / g for TRFC, which is an increase of 16.6 mL / g.

[0086] Based on the above, it can be seen that the pore size of the phenolic resin-based carbon material obtained in Comparative Example 1 is relatively large, the separation effect of methane and nitrogen is relatively poor, and the adsorption capacity of carbon dioxide is relatively low. However, the nitrogen-doped phenolic resin-based carbon material obtained in the present invention can enhance the methane enrichment effect and carbon dioxide adsorption capacity of the carbonized carbon material.

[0087] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent, characterized in that: The steps include: 1) mixing ammonia water, anhydrous ethanol, resorcinol and water to obtain an alkaline resorcinol solution; 2) mixing the alkaline resorcinol solution with formaldehyde to obtain a resorcinol formaldehyde resin suspension; 3) The resorcinol formaldehyde resin suspension is mixed with the aminopyrimidine solution and then subjected to hydrothermal treatment and heat treatment in sequence to obtain a nitrogen-doped phenolic resin-based carbon adsorbent.

2. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 1, characterized in that: In the step 1), the ratio of ammonia water, anhydrous ethanol, resorcinol and water is 0.3-0.8 mL: 25-45 mL: 4-6 g: 40-80 mL; The mixing time is 1 to 3 hours, and the mixing speed is 300 to 500 rpm.

3. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 2, characterized in that: In the step 2), the dosage ratio of formaldehyde to resorcinol is 5-15 mL: 4-6 g; The mixing speed is 300-500 rpm, and the mixing time is 6-8 hours.

4. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 2 or 3, characterized in that: In the step 3), the aminopyrimidine solution is obtained by mixing ammonia water, anhydrous ethanol, water, formaldehyde and aminopyrimidine; The aminopyrimidine is a mixed solution of 2,4,6-triaminopyrimidine and melamine or 2,4,6-triaminopyrimidine; When the aminopyrimidine is a mixed solution of 2,4,6-triaminopyrimidine and melamine, the mass ratio of 2,4,6-triaminopyrimidine to melamine is 0.8-1.2:0.8-1.

2.

5. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 4, characterized in that: The dosage ratio of the ammonia water, anhydrous ethanol, water, formaldehyde and aminopyrimidine is 0.1-0.3 mL: 10-15 mL: 18-22 mL: 3-5 mL: 1.1-1.2 g; The mixing time is 20 to 70 minutes, and the mixing temperature is 20 to 30°C.

6. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 1, characterized in that: In the step 3), the mixing time is 50 to 70 minutes; The volume ratio of the resorcinol formaldehyde resin suspension to the aminopyrimidine solution is 65-130:30-45.

7. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 6, characterized in that: In the step 3), the temperature of the hydrothermal treatment is 100 to 150° C., and the time of the hydrothermal treatment is 20 to 26 hours.

8. The method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to claim 6 or 7, characterized in that: In the step 3), the heat treatment includes a first stage heat treatment and a second stage heat treatment; In the first stage of heat treatment, the heating rate is 1-3°C / min, the heat treatment temperature is 180-220°C, and the heat treatment time is 40-70min; In the second stage of heat treatment, the heating rate is 1-3°C / min, the heat treatment temperature is 750-850°C, and the heat treatment time is 3-5h.

9. The nitrogen-doped phenolic resin-based carbon adsorbent prepared by the method for preparing a nitrogen-doped phenolic resin-based carbon adsorbent according to any one of claims 1 to 8.

10. Use of the nitrogen-doped phenolic resin-based carbon adsorbent according to claim 9 in the field of gas separation.

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