A nitrogen-doped hierarchical porous carbon material and its preparation method and application

Abstract

The present invention belongs to the technical field of porous carbon materials, and specifically relates to a nitrogen-doped hierarchical porous carbon material and a preparation method and application thereof. The preparation method of the nitrogen-doped hierarchical porous carbon material provided by the present invention utilizes the rectangular morphology characteristics of the nickel cobalt acetate hydroxide hard template to construct macropores with specific shapes in the carbon material; at the same time, a nitrogen source is added during the chemical activation process to form a large number of micropores while completing nitrogen doping. The preparation method is simple, and the obtained nitrogen-doped hierarchical porous carbon material shows good adsorption characteristics for CO2.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous carbon materials, and in particular relates to a nitrogen-doped graded porous carbon material and a preparation method and application thereof. Background Art

[0002] Hierarchical porous carbon materials contain at least two different size levels of pores (e.g., micropore-mesopore, micropore-mesopore-macroporous), among which micropores can give carbon materials a high specific surface area, while mesopores and macropores are conducive to rapid diffusion and mass transfer. Therefore, hierarchical porous carbon materials are widely used in many different fields. After doping nitrogen atoms in carbon materials, their physical and chemical properties can be changed. Since nitrogen atoms have lone pairs of electrons, they can improve the electron transport properties of carbon materials and enhance the alkalinity of carbon materials. Studies have shown that doping nitrogen atoms can enhance the adsorption and catalytic properties of carbon materials.

[0003] Since pores of different sizes often require corresponding preparation strategies, the synthesis method of nitrogen-doped hierarchical porous carbon materials is more complicated. For example, in the synthesis process, it is often necessary to use the template method in combination with the activation method, or to use multiple templates at the same time. The hard template method is widely used in the preparation of porous carbon materials and generally consists of the following steps: (1) immersing the carbon precursor into the template agent; (2) polymerizing the precursor on the template agent to obtain a nitrogen-containing precursor, and then obtaining a carbon material with a specific morphology through high-temperature carbonization; (3) removing the template agent from the carbon material; (4) adding a pore expander to the carbon material, and performing high-temperature carbonization to expand the pores to obtain a porous carbon material. The traditional preparation method has complicated procedures and a limited degree of nitrogen doping. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a nitrogen-doped hierarchical porous carbon material and a preparation method and application thereof. The preparation method of the nitrogen-doped hierarchical porous carbon material of the present invention is simple, and the prepared nitrogen-doped hierarchical porous carbon material has a high nitrogen content.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a nitrogen-doped hierarchical porous carbon material, comprising the following steps:

[0007] Using a solvothermal method, nickel acetate and cobalt acetate are prepared into a nickel cobalt acetate hydroxide hard template, wherein the nickel cobalt acetate hydroxide hard template is in a rectangular parallelepiped shape;

[0008] The nickel cobalt acetate hydroxide hard template is mixed with a carbon source for carbonization, and the obtained carbonization product is subjected to a hydrothermal reaction with hydrochloric acid to obtain a carbon material precursor;

[0009] The carbon material precursor, urea, an activator and water are mixed and dried, and the obtained mixture is calcined under an inert atmosphere to obtain the nitrogen-doped hierarchical porous carbon material.

[0010] Preferably, the mass ratio of the carbon source to the nickel cobalt acetate hydroxide hard template is 1:1-2.

[0011] Preferably, the phenolic resin is used in the form of a phenolic resin ethanol solution, and the concentration of the phenolic resin in the phenolic resin ethanol solution is 30 wt %.

[0012] Preferably, the calcination temperature is 700-800° C. and the calcination time is 2 hours.

[0013] Preferably, the activator includes one or more of KOH, K2CO3, KHCO3, CH3COOK, K2C2O4 and NaOH.

[0014] Preferably, the mass ratio of the activator to the carbon material precursor is 1 to 3:1.

[0015] Preferably, the reaction temperature of the solvothermal method is 90° C. and the reaction time is 16 h.

[0016] Preferably, the solvent of the solvothermal method is ethanol, the mass ratio of the ethanol to the acetate is 100:0.64, the acetate includes nickel acetate and cobalt acetate, and the mass ratio of the nickel acetate to the cobalt acetate is 1:1.

[0017] The present invention also provides a nitrogen-doped hierarchical porous carbon material obtained by the preparation method described in the above technical solution, wherein the specific surface area of ​​the nitrogen-doped hierarchical porous carbon material is 600 to 1500 m 2 / g, and the nitrogen content is 5 to 10 wt%.

[0018] The present invention also provides the use of the nitrogen-doped hierarchical porous carbon material described in the above technical solution in CO2 adsorption.

[0019] The present invention provides a method for preparing a nitrogen-doped hierarchical porous carbon material, comprising the following steps:

[0020] Using a solvothermal method, nickel acetate and cobalt acetate are prepared into a nickel cobalt acetate hydroxide hard template, wherein the nickel cobalt acetate hydroxide hard template is in a rectangular parallelepiped shape;

[0021] The nickel cobalt acetate hydroxide hard template is mixed with a carbon source for carbonization, and the obtained carbonization product is subjected to a hydrothermal reaction with hydrochloric acid to obtain a carbon material precursor;

[0022] The carbon material precursor, urea, an activator and water are mixed and dried, and the obtained mixture is calcined under an inert atmosphere to obtain the nitrogen-doped hierarchical porous carbon material.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The method for preparing the nitrogen-doped hierarchical porous carbon material of the present invention utilizes the rectangular morphology characteristics of the nickel cobalt acetate hydroxide hard template to form a rectangular channel in the carbon material, and at the same time, nitrogen source urea is added during the chemical activation (adding an activator and calcining) process to form a hierarchical channel structure and complete nitrogen doping at the same time. The preparation method is simple, and the prepared nitrogen-doped hierarchical porous carbon material has a high nitrogen content of 5 to 10 wt%, a large specific surface area of ​​600 to 1500 m 2 / g.

[0025] The present invention also provides an application of the nitrogen-doped graded porous carbon material obtained by the preparation method described in the above technical scheme. The CO2 adsorption amounts of the carbon materials prepared in Examples 1 to 3 are 5.8 mmol / g, 10.0 mmol / g and 12.7 mmol / g, respectively, showing good adsorption characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 The scanning electron microscope test results of the nickel cobalt acetate hydroxide hard template in Examples 1 to 3 are shown;

[0028] Figure 2 The scanning electron microscope test results of the nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3;

[0029] Figure 3 This is a graph showing the Raman spectrum test results of the nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3;

[0030] Figure 4 This is the XPS test N1s spectrum of the nitrogen-doped hierarchical porous carbon material prepared in Examples 1 to 3;

[0031] Figure 5 The N2 adsorption-desorption curves of the nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3 at -196°C;

[0032] Figure 6 This is the CO2 adsorption isotherm of the nitrogen-doped hierarchical porous carbon material prepared in Examples 1 to 3 at 25°C. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing a nitrogen-doped hierarchical porous carbon material, comprising the following steps:

[0034] Using a solvothermal method, nickel acetate and cobalt acetate are prepared into a nickel cobalt acetate hydroxide hard template, wherein the nickel cobalt acetate hydroxide hard template is in a rectangular parallelepiped shape;

[0035] The nickel cobalt acetate hydroxide hard template is mixed with a carbon source for carbonization, and the obtained carbonization product is subjected to a hydrothermal reaction with hydrochloric acid to obtain a carbon material precursor;

[0036] The carbon material precursor, urea, an activator and water are mixed and dried, and the obtained mixture is calcined under an inert atmosphere to obtain the nitrogen-doped hierarchical porous carbon material.

[0037] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0038] The invention adopts a solvent thermal method to prepare nickel acetate and cobalt acetate into a nickel cobalt acetate hydroxide hard template, wherein the nickel cobalt acetate hydroxide hard template is in a rectangular parallelepiped shape.

[0039] In the present invention, the solvent of the solvothermal method is preferably ethanol, the mass ratio of the ethanol to the acetate is preferably 100:0.64, the acetate includes nickel acetate and cobalt acetate, and the mass ratio of the nickel acetate to the cobalt acetate is preferably 1:1.

[0040] In the present invention, the nickel acetate is preferably nickel acetate tetrahydrate, and the cobalt acetate is preferably cobalt acetate tetrahydrate.

[0041] In the present invention, the solvothermal method preferably further includes adding polyvinyl pyrrolidone (PVP) before the reaction. The polyvinyl pyrrolidone is preferably polyvinyl pyrrolidone-K30. The polyvinyl pyrrolidone can regulate the morphology of the hard template to obtain a hard template with a rectangular morphology; the mass ratio of nickel acetate, cobalt acetate and polyvinyl pyrrolidone is preferably 0.32:0.32:1.5.

[0042] In the present invention, the reaction temperature of the solvothermal method is preferably 90° C., the reaction time is preferably 16 h, and the transparent solution formed by ethanol, nickel acetate, cobalt acetate and polyvinyl pyrrolidone is preferably subjected to solvothermal reaction in a polytetrafluoroethylene reactor, and the capacity of the polytetrafluoroethylene reactor is preferably 200 mL.

[0043] In the present invention, after the solvothermal method is completed, it is preferred that the obtained product is filtered, washed and dried in sequence to obtain the nickel cobalt acetate hydroxide hard template; the washing solvent is preferably ethanol, and the number of washings is preferably 3 times; the drying temperature is preferably 80°C, and the drying time is preferably 3 hours.

[0044] After obtaining the nickel cobalt acetate hydroxide hard template, the present invention mixes the nickel cobalt acetate hydroxide hard template with a carbon source for carbonization, and hydrothermally reacts the obtained carbonization product with hydrochloric acid to obtain a carbon material precursor.

[0045] In the present invention, the carbon source is preferably phenolic resin, and the phenolic resin is preferably used in the form of phenolic resin ethanol solution, and the concentration of phenolic resin in the phenolic resin ethanol solution is preferably 30wt%. The present invention has no special requirements for the preparation method of the phenolic resin ethanol solution. In the specific embodiment of the present invention, the following method is used to prepare it: Under the temperature condition of 40-42°C, 12.2g of phenol is melted to form a liquid, and then 2.6g of sodium hydroxide solution (20wt%) is added. After stirring for 10min, 21g of formalin solution (formaldehyde content 37wt%) is slowly added dropwise at a temperature below 50°C. The mixed solution is stirred at 70°C for 1h, then cooled to room temperature, and then hydrochloric acid (0.6mol / L) is used to adjust its pH value to 7.0. The obtained product is vacuum dried at 50°C for 24h to remove moisture, and then the precipitated sodium chloride particles are filtered to remove, and then ethanol is added to prepare a 30wt% phenolic resin ethanol solution.

[0046] In the present invention, the mass ratio of the carbon source to the nickel cobalt acetate hydroxide hard template is preferably 1:1-2, more preferably 1:2.

[0047] The present invention preferably first dries the mixture obtained by mixing the nickel cobalt acetate hydroxide hard template and the carbon source, and then performs the carbonization; the nickel cobalt acetate hydroxide hard template and the carbon source are preferably mixed by stirring, the stirring temperature is preferably room temperature, the stirring time is preferably 2h, and a translucent mixture is preferably obtained after the mixing; the drying temperature is preferably 100°C, and the time is preferably 24h.

[0048] In the present invention, the carbonization temperature is preferably 500° C., the time is preferably 2 h, the carbonization is preferably carried out under an inert atmosphere, the inert atmosphere is preferably N 2 , and the flow rate of N 2 is preferably 60 mL / min.

[0049] In the present invention, the temperature of the hydrothermal reaction is preferably 180° C., and the time is preferably 4 hours.

[0050] In the present invention, the concentration of the hydrochloric acid is preferably 36.5wt%, and the usage ratio of the hydrochloric acid to the nickel cobalt acetate hydroxide hard template is preferably 50mL:1-2g; the addition of the hydrochloric acid can remove the nickel cobalt acetate hydroxide hard template in the carbonization product.

[0051] In the present invention, the hydrothermal reaction preferably further includes water washing and drying in sequence, and the water washing is preferably neutral; the drying temperature is preferably 100° C., and the drying time is preferably 5 hours.

[0052] After obtaining the carbon material precursor, the present invention mixes the carbon material precursor, urea, an activator and water, and then dries the mixture, and calcines the obtained mixture under an inert atmosphere to obtain the nitrogen-doped hierarchical porous carbon material.

[0053] In the present invention, the mass ratio of urea to carbon material precursor is preferably 2:1.

[0054] In the present invention, the activator preferably includes one or more of KOH, K2CO3, KHCO3, CH3COOK, K2C2O4 and NaOH.

[0055] In the present invention, the mass ratio of the activator to the carbon material precursor is preferably 1 to 3:1, more preferably 2:1.

[0056] In the present invention, the carbon material precursor, urea, activator and water are preferably mixed by stirring, the stirring temperature is preferably room temperature, and the stirring time is preferably 2 hours.

[0057] In the present invention, the usage ratio of water to carbon material precursor is preferably 15 mL:1 g.

[0058] In the present invention, the carbon material precursor, urea, activator and water are mixed and dried at a temperature of preferably 100° C. and for a time of preferably 5 hours.

[0059] In the present invention, the calcination temperature is preferably 700-800°C, the calcination time is preferably 2 hours, the calcination inert atmosphere is preferably N2, and the flow rate of N2 is preferably 60 mL / min.

[0060] In the present invention, the heating rate to the calcination temperature is preferably 5° C. / min.

[0061] In the present invention, after the calcination, it is preferred that washing and drying are performed in sequence to obtain the nitrogen-doped graded porous carbon material; the washing preferably includes acid washing and water washing in sequence, the acid washing reagent is preferably hydrochloric acid, the concentration of the hydrochloric acid is preferably 10wt%, and the water washing is preferably neutral; the drying temperature is preferably 100°C, and the time is preferably 5h.

[0062] The present invention also provides a nitrogen-doped hierarchical porous carbon material obtained by the preparation method described in the above technical solution, wherein the specific surface area of ​​the nitrogen-doped hierarchical porous carbon material is 600 to 1500 m 2 / g, and the nitrogen content is 5 to 10 wt%.

[0063] In the present invention, the specific surface area of ​​the nitrogen-doped hierarchical porous carbon material is preferably 672 to 1398 m 2 / g, and the nitrogen content is preferably 5.76 to 9.26 wt%.

[0064] In the present invention, the nitrogen-doped hierarchical porous carbon material contains micropores formed by a chemical activation process and macropores formed by adding a nickel acetate cobalt hydroxide hard template; the nitrogen-doped hierarchical porous carbon material has a high specific surface area, and due to the use of the hard template, the macropores have a morphological feature similar to a rectangular parallelepiped.

[0065] The present invention also provides the use of the nitrogen-doped hierarchical porous carbon material described in the above technical solution in CO2 adsorption.

[0066] The method for preparing the nitrogen-doped hierarchical porous carbon material provided by the present invention utilizes the specific morphology of the hard template itself to construct macropores with specific shapes in the carbon material; at the same time, a large number of micropores are formed by chemical activation, thereby preparing a carbon material with a hierarchical porous structure. At the same time, utilizing its high specific surface area and nitrogen doping characteristics, the nitrogen-doped hierarchical porous carbon material prepared by the present invention exhibits good adsorption characteristics for CO2.

[0067] In order to further illustrate the present invention, the nitrogen-doped hierarchical porous carbon material and its preparation method and application of the present invention are described in detail below in combination with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0068] Example 1

[0069] Synthesis of nickel cobalt acetate hydroxide hard template: Add 0.32g nickel acetate tetrahydrate and 0.32g cobalt acetate tetrahydrate to 100g ethanol, then add 1.5g polyvinyl pyrrolidone (K30), stir to form a transparent solution. The resulting solution was placed in a 200mL polytetrafluoroethylene reactor and reacted at 90°C for 16h. After the reaction, the product was filtered, washed with ethanol 3 times, and dried at 80°C for 3h to obtain a nickel cobalt acetate hydroxide hard template.

[0070] Synthesis of phenolic resin: 12.2g of phenol was melted at 41°C to form a liquid, and then 2.6g of sodium hydroxide solution (20wt%) was added. After stirring for 10min, 21g of formalin solution (formaldehyde content 37wt%) was slowly added dropwise at a temperature below 50°C. The mixed solution was stirred at 70°C for 1h, then cooled to room temperature, and then its pH value was adjusted to 7.0 using hydrochloric acid (0.6mol / L). The obtained product was vacuum dried at 50°C for 24h to remove moisture, and then the precipitated sodium chloride particles were filtered out, and then ethanol was added to prepare a 30wt% phenolic resin ethanol solution.

[0071] Synthesis of nitrogen-doped hierarchical porous carbon material precursor: 1.0g of nickel cobalt acetate hydroxide hard template was added to 3.33g of phenolic resin ethanol solution (30wt%), stirred at room temperature for 2h to form a uniform translucent mixture, and placed in an oven at 100℃ for 24h. The obtained mixture was placed in a tubular furnace, heated to 500℃ for 2h under N2 protection (60mL / min). After natural cooling, 50mL of hydrochloric acid (36.5wt%) was added to the carbonized product, hydrothermally reacted at 180℃ for 4h, then washed with water until neutral, and dried at 100℃ for 5h to obtain a carbon material precursor.

[0072] Synthesis of nitrogen-doped hierarchical porous carbon material: 2.0g urea and 1.0g KOH were dissolved in 15mL deionized water, and then 1.0g carbon material precursor was added, stirred at room temperature for 2h, and dried at 100℃ for 5h. The obtained mixture was placed in a tube furnace, and the temperature was raised to 700℃ at 5℃ / min under N2 protection (60mL / min) for 2h. After natural cooling, the obtained product was treated with 70mL hydrochloric acid (10wt%), washed with water until neutral, and dried at 100℃ for 5h to obtain nitrogen-doped hierarchical porous carbon material.

[0073] Example 2

[0074] The nickel cobalt acetate hydroxide hard template and phenolic resin ethanol solution in this embodiment are the same as those in Example 1.

[0075] Synthesis of nitrogen-doped hierarchical porous carbon material precursor: Add 2.0g of nickel cobalt acetate hydroxide hard template to 3.33g of phenolic resin ethanol solution (30wt%), stir at room temperature for 2h to form a uniform translucent mixture, and put it into an oven at 100℃ for 24h. The obtained mixture was placed in a tubular furnace and heated to 500℃ for 2h under N2 protection (60mL / min). After natural cooling, 50mL of hydrochloric acid (36.5wt%) was added to the carbonized product, and hydrothermally reacted at 180℃ for 4h, then washed with water until neutral, and dried at 100℃ for 5h to obtain a carbon material precursor.

[0076] Synthesis of nitrogen-doped hierarchical porous carbon material: 2.0g urea and 1.0g KHCO3 were dissolved in 15mL deionized water, and then 1.0g carbon material precursor was added, stirred at room temperature for 2h, and dried at 100℃ for 5h. The obtained mixture was placed in a tube furnace, and the temperature was raised to 800℃ at 5℃ / min under N2 protection (60mL / min) for 2h. After natural cooling, the obtained product was treated with 70mL hydrochloric acid (10wt%), washed with water until neutral, and dried at 100℃ for 5h to obtain nitrogen-doped hierarchical porous carbon material.

[0077] Example 3

[0078] The nickel cobalt acetate hydroxide hard template and phenolic resin ethanol solution in this embodiment are the same as those in Example 1.

[0079] Synthesis of nitrogen-doped hierarchical porous carbon material precursor: Add 2.0g of nickel cobalt acetate hydroxide hard template to 3.33g of phenolic resin ethanol solution (30wt%), stir at room temperature for 2h to form a uniform translucent mixture, and put it into an oven at 100℃ for 24h. The obtained mixture was placed in a tubular furnace and heated to 500℃ for 2h under N2 protection (60mL / min). After natural cooling, 50mL of hydrochloric acid (36.5wt%) was added to the carbonized product, and hydrothermally reacted at 180℃ for 4h, then washed with water until neutral, and dried at 100℃ for 5h to obtain a carbon material precursor.

[0080] Synthesis of nitrogen-doped hierarchical porous carbon material: 2.0g urea and 2.0g KHCO3 were dissolved in 15mL deionized water, and then 1.0g carbon material precursor was added, stirred at room temperature for 2h, and dried at 100℃ for 5h. The obtained mixture was placed in a tube furnace, and the temperature was raised to 800℃ at 5℃ / min under N2 protection (60mL / min) for 2h. After natural cooling, the obtained product was treated with 70mL hydrochloric acid (10wt%), washed with water until neutral, and dried at 100℃ for 5h to obtain nitrogen-doped hierarchical porous carbon material.

[0081] Figure 1 This is a scanning electron microscope test photo of nickel cobalt acetate hydroxide hard template. Figure 1 It can be seen that the nickel cobalt acetate hydroxide hard template has a morphological feature similar to a rectangular parallelepiped, with a length of 0.5 to 1 μm and a width of 0.2 to 0.5 μm.

[0082] Figure 2 The scanning electron microscope photos of nitrogen-doped hierarchical porous carbon materials prepared by the nickel cobalt acetate hydroxide hard template in Examples 1 to 3. After the hard template was removed by hydrochloric acid, macropores similar to rectangular shapes were formed in the carbon material, that is, these macropores replicated the morphological characteristics of the hard template. In addition, the mass of the nickel cobalt acetate hydroxide hard template and the phenolic resin in Example 1 is relatively small, the number of macropores is relatively small, and there are obvious intervals between the macropores; in Examples 2 to 3, as the amount of hard template added increases, the number of macropores formed increases, and some macropores are connected to each other.

[0083] Figure 3 The Raman spectra of the carbon materials in Examples 1 to 3 are shown in Figure 1. -1 With 1580cm -1 The defect (D) and graphitization (G) characteristic peaks of carbon materials were observed at D / I G The values ​​are 1.23, 1.20, and 1.36 respectively. The higher I D / I G The values ​​also show that the graphitization degree of the prepared carbon material is low and there are many defects on the surface.

[0084] XPS test was performed on the nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3. The test results are shown in Figure 4 . Figure 4 The stronger N1s characteristic peak indicates that nitrogen is successfully doped into the carbon material. The nitrogen contents of the carbon materials in Examples 1 to 3 are 9.26wt%, 8.46wt% and 5.76wt%, respectively.

[0085] The nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3 were subjected to nitrogen adsorption and desorption tests. The test method was a static volume adsorption test. The test results are shown in Figure 5 .from Figure 5 It can be seen that the nitrogen adsorption amount increases rapidly in the low-pressure stage, which is a typical feature of micropore adsorption, indicating that a large number of micropores are formed in the obtained carbon materials after activation treatment with different activators. The specific surface areas of the nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3 are 672 m 2 / g, 1231m 2 / g and 1398m 2 / g, and the micropore specific surface area is 600m 2 / g, 1143m 2 / g and 1240m 2 / g, and the proportion of micropores is 89%, 93% and 89% respectively.

[0086] The nitrogen-doped hierarchical porous carbon materials prepared in Examples 1 to 3 were tested for CO2 adsorption properties, and the test included the following steps:

[0087] 100 mg of nitrogen-doped hierarchical porous carbon material was added to the test sample chamber and heated to 250 °C for vacuum degassing for 3 h;

[0088] The ambient temperature of the test sample chamber is set, and the CO2 pressure is gradually increased from the vacuum state. The adsorption amount at each equilibrium pressure is measured until the equilibrium pressure reaches 20.0 bar, thereby obtaining a complete CO2 adsorption isotherm.

[0089] After the CO2 adsorption test is completed, the sample chamber is heated to 100°C for vacuum treatment to complete CO2 desorption.

[0090] CO2 adsorption test results are shown in Figure 6 .from Figure 6 It can be seen that under the conditions of 25°C and 20 bar pressure, the CO2 adsorption amounts of the carbon materials in Examples 1 to 3 were 5.8 mmol / g, 10.0 mmol / g and 12.7 mmol / g, respectively, showing good adsorption characteristics.

[0091] The above test results indicate that the preparation method of the present invention can conveniently synthesize nitrogen-doped hierarchical porous carbon materials with specific morphology and high specific surface area, and these carbon materials can be used to adsorb CO2 with good adsorption properties.

[0092] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a nitrogen-doped hierarchical porous carbon material, characterized in that: The following steps are involved: A solvothermal method is used to prepare a nickel-cobalt acetate hydroxide hard template from nickel acetate and cobalt acetate, wherein the nickel-cobalt acetate hydroxide hard template is in a rectangular shape; the reaction temperature of the solvothermal method is 90° C., and the reaction time is 16 hours; the solvent of the solvothermal method is ethanol, and the mass ratio of the ethanol to the acetate is 100:0.64; the acetate includes nickel acetate and cobalt acetate, and the mass ratio of the nickel acetate to the cobalt acetate is 1:1; The nickel cobalt acetate hydroxide hard template is mixed with a carbon source for carbonization, and the obtained carbonization product is subjected to a hydrothermal reaction with hydrochloric acid to obtain a carbon material precursor; the mass ratio of the carbon source to the nickel cobalt acetate hydroxide hard template is 1:2; the carbon source is a phenolic resin, and the phenolic resin is used in the form of a phenolic resin ethanol solution, and the concentration of the phenolic resin in the phenolic resin ethanol solution is 30wt%; The carbon material precursor, urea, activator and water are mixed and dried, and the obtained mixture is calcined under an inert atmosphere to obtain the nitrogen-doped graded porous carbon material; the mass ratio of urea to carbon material precursor is 2:1; the mass ratio of the activator to carbon material precursor is 1:1; the calcination temperature is 800°C and the time is 2h; the activator is KHCO3.

2. The nitrogen-doped hierarchical porous carbon material obtained by the preparation method according to claim 1, characterized in that: The specific surface area of ​​the nitrogen-doped hierarchical porous carbon material is 600 to 1500 m 2 / g, and the nitrogen content is 5 to 10 wt%.

3. Use of the nitrogen-doped hierarchical porous carbon material according to claim 2 in CO2 adsorption.

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