A microwave-assisted method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon

Abstract

The present invention discloses a microwave-assisted method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon. The method comprises the following steps: (1) crushing deashed refined coal liquefaction asphalt to obtain asphalt powder; (2) mixing the asphalt powder with a template and a nitrogen source, and then performing microwave-assisted pre-oxidation; (3) carbonizing the pre-oxidation product; (4) adding an acidic solution to the carbonized product and stirring and mixing to form a slurry; and then performing microwave-assisted pickling on the slurry; (5) washing the pickled product to a neutral pH, and then drying it; and (6) activating the dried product to obtain asphalt-based nitrogen-doped functionalized mesoporous carbon. The method of the present invention uses microwave-assisted technology to reduce the carbonization temperature, increase the specific surface area of ​​the product, and simplify the pickling process. It can effectively solve the problems of easy collapse and damage of the pore structure of mesoporous carbon materials and incomplete template removal in the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy material preparation. Specifically, the present invention relates to a method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with the assistance of microwaves. Background Art

[0002] Highly stable mesoporous carbon materials, with their unique pore size distribution and large specific surface area, are widely used in fuel cells, supercapacitor electrode materials, and catalyst supports. The production of carbon materials from inexpensive and abundant coal-based feedstocks meets my country's current energy and environmental needs. Coal liquefaction pitch, with its high carbon content, excellent thermal stability, and high viscosity, is an important carbon source for the preparation of mesoporous carbon.

[0003] Numerous traditional methods exist for preparing coal-based mesoporous carbon, but these methods suffer from poor stability, uneven pore size distribution, and low synthesis efficiency, limiting their practical applications. For example, existing methods utilize pyrolysis to prepare coal-based mesoporous carbon. While this process is simple and easily scalable, the resulting mesoporous carbon is of poor quality, with relatively low specific surface area and porosity. Chemical and chemical activation methods, while significantly increasing the specific surface area and pore structure of carbon materials, increase the difficulty and cost of environmental treatment. Currently, the most widely used methods for preparing mesoporous carbon are hard and soft template methods, which offer precise control over pore size distribution and pore structure. However, the template-based carbonization, activation, and acid washing processes are complex, lengthy, and inefficient, and the template removal process is incomplete and prone to pollution. This inefficient and costly synthesis method is not suitable for large-scale production. Furthermore, the high-temperature carbonization step involved in the synthesis process can easily damage the pore structure, compromising the performance of the mesoporous carbon material. Therefore, there is an urgent need to develop an efficient, low-cost, and environmentally friendly synthesis method that ensures a uniform, stable, and controllable pore structure for mesoporous carbon. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, an embodiment of the present invention provides a method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon with microwave assistance.

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon with microwave assistance, comprising the following steps:

[0006] (1) crushing the deashed refined coal liquefaction pitch to obtain pitch powder;

[0007] (2) mixing the asphalt powder with a template and a nitrogen source, and then performing microwave-assisted pre-oxidation treatment;

[0008] (3) carbonizing the pre-oxidation product obtained in step (2);

[0009] (4) adding an acidic solution to the carbonized product obtained in step (3) and stirring to form a slurry; and then subjecting the slurry to a microwave-assisted acid washing treatment;

[0010] (5) washing the acid-washed product obtained in step (4) until the pH is neutral, and then drying it;

[0011] (6) Activating the dried product obtained in step (5) to obtain the asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0012] In some embodiments, in step (1), the softening point of the deashed refined coal liquefaction pitch is 100-130° C., and the quinoline insoluble matter is less than 0.01%;

[0013] And / or, the crushing process takes 5 to 15 minutes;

[0014] And / or, the particle size of the asphalt powder is less than 100 mesh.

[0015] In some embodiments, in step (2), the mass ratio of the asphalt powder to the template is (2-4):(6-8), and the amount of the nitrogen source added accounts for 0.1% to 0.5% of the total mass of the asphalt powder, the template and the nitrogen source;

[0016] Preferably, the template comprises at least one of nano-magnesium oxide, block copolymer Pluronic F127, molecular sieve SBA-15, and silicon dioxide;

[0017] Preferably, the nitrogen source includes at least one of melamine, cetyltrimethylammonium chloride and dicyanamide.

[0018] In some embodiments, in step (2), the microwave-assisted pre-oxidation treatment is carried out in an air atmosphere, the microwave power is ≥1500W, the temperature of the microwave-assisted pre-oxidation treatment is 150-250°C, and the pre-oxidation time is 15-35 minutes.

[0019] In some embodiments, in step (3), the carbonization treatment is carried out in a nitrogen atmosphere with a nitrogen flow rate of 20 to 40 mL / min; the carbonization treatment temperature is 600 to 1000°C, the heating rate is 5 to 10°C / min, and the carbonization time is 1 to 3 hours.

[0020] In some embodiments, in step (4), the acidic solution includes at least one of a hydrochloric acid solution, a phosphoric acid solution, a sulfuric acid solution, and a nitric acid solution, and the concentration of the acidic solution is 1 to 3 mol / L;

[0021] And / or, the microwave-assisted pickling treatment is carried out in an air atmosphere, the microwave power is ≤300W, the temperature of the microwave-assisted pickling treatment is 30-50°C, and the pickling time is 5-15 minutes.

[0022] In some embodiments, in step (5), the washing agent used in the washing comprises at least one of water and ethanol;

[0023] And / or, the drying method is vacuum drying, the drying temperature is 40-60° C., and the drying time is 8-12 hours.

[0024] In some embodiments, in step (6), the activation medium used in the activation treatment is water vapor or carbon monoxide, and the flow rate of the activation medium is 5 to 15 mL / min;

[0025] And / or, the activation treatment is carried out in a nitrogen atmosphere with a nitrogen flow rate of 20 to 40 mL / min; the activation treatment temperature is 800 to 1000° C., the heating rate is 5 to 10° C. / min, and the activation time is 1 to 2 h.

[0026] In a second aspect, an embodiment of the present invention further provides a pitch-based nitrogen-doped functionalized mesoporous carbon, wherein the pitch-based nitrogen-doped functionalized mesoporous carbon is prepared by the method described in the first aspect.

[0027] In a third aspect, an embodiment of the present invention further proposes an application of the asphalt-based nitrogen-doped functionalized mesoporous carbon as described in the second aspect in the field of new energy materials.

[0028] The advantages and beneficial effects of the embodiments of the present invention are as follows:

[0029] The present invention discloses a microwave-assisted method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon. The method utilizes microwaves to pre-oxidize a carbon precursor, a template, and a nitrogen source mixture, thereby uniformly mixing the three. This method effectively increases the specific surface area of ​​the mesoporous carbon product and helps reduce the carbonization temperature, thereby solving the problem of easy collapse and damage of the pore structure of the carbon material. The method also utilizes microwave treatment to perform acid washing, replacing traditional filtering and stirring processes, thereby effectively solving the problems of incomplete template removal and environmental pollution. In addition, the method of the present invention selects a suitable nitrogen source so that nitrogen can be doped into the mesoporous carbon while forming pores, effectively improving the conductive properties of the material. The method of the present invention is simple in preparation process, easy to operate, has a short synthesis time, high efficiency, and low cost, significantly reducing the synthesis cost of the mesoporous carbon material and improving production efficiency. The prepared mesoporous carbon material has good comprehensive properties, meeting its application requirements in the field of new energy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a process flow chart of a method for microwave-assisted preparation of pitch-based nitrogen-doped functionalized mesoporous carbon according to an embodiment of the present invention.

[0031] Figure 2 These are scanning electron microscope images of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention at different magnifications.

[0032] Figure 3 Transmission electron micrographs of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention at different magnifications.

[0033] Figure 4 This is the EDS element mapping diagram of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention.

[0034] Figure 5 This is the X-ray diffraction spectrum of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention.

[0035] Figure 6 This is a Raman spectrum of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention.

[0036] Figure 7 This is the infrared spectrum of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention.

[0037] Figure 8 This is the thermogravimetric curve of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 of the present invention.

[0038] Figure 9 1 and 2 are nitrogen adsorption-desorption isotherms of the mesoporous carbons prepared in Example 1 and Comparative Example 1 of the present invention.

[0039] Figure 10 The pore size distribution curves of the mesoporous carbons prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0040] Figure 11 The conductive performance test diagram of the mesoporous carbon prepared in Example 1 and Comparative Example 2 of the present invention.

[0041] Figure 12 This is a scanning electron microscope image of the mesoporous carbon prepared in Comparative Example 3.

[0042] Figure 13 The nitrogen adsorption-desorption isotherms of the mesoporous carbons prepared in Example 1 and Comparative Example 3 of the present invention are shown. DETAILED DESCRIPTION

[0043] The following describes in detail embodiments of the present invention. The embodiments are exemplary and intended to explain the present invention, but are not to be construed as limiting the present invention.

[0044] Where values ​​are described herein as ranges, it should be understood that such disclosure includes disclosure of all possible sub-ranges within that range, as well as specific values ​​falling within that range, regardless of whether a specific value or sub-range is explicitly stated.

[0045] As used herein, the words "comprise," "include," and "includes" and variations thereof mean that additional elements or integers may be included although permitted but not specifically described.

[0046] In this article, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0047] First, as Figure 1 As shown, the embodiment of the present invention provides a method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon with microwave assistance, comprising the following steps:

[0048] (1) crushing the deashed refined coal liquefaction pitch to obtain pitch powder;

[0049] (2) mixing the asphalt powder with a template and a nitrogen source, and then performing microwave-assisted pre-oxidation treatment;

[0050] (3) carbonizing the pre-oxidation product obtained in step (2);

[0051] (4) adding an acidic solution to the carbonized product obtained in step (3) and stirring to form a slurry; and then subjecting the slurry to a microwave-assisted acid washing treatment;

[0052] (5) washing the acid-washed product obtained in step (4) until the pH is neutral, and then drying it;

[0053] (6) Activating the dried product obtained in step (5) to obtain the asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0054] In some embodiments, in step (1), the softening point of the deashed refined coal liquefaction pitch is 100-130°C, and the quinoline insoluble matter is <0.01%. The inventors have found that if the softening point of the coal liquefaction pitch is too low, it will lead to the easy occurrence of the phenomenon of stranding when preparing the carbon material, and it will be difficult to form a heat-resistant structure, thereby affecting the performance and structural stability of the carbon material. The inventors have also found that when the pitch has too high a quinoline insoluble matter content, the strength, density and antioxidant properties will decrease when preparing the carbon material. Therefore, in the embodiment of the present invention, the softening point and quinoline insoluble matter content of the coal liquefaction pitch are controlled within the above ranges.

[0055] And / or, the crushing process takes 5 to 15 minutes;

[0056] And / or, the particle size of the asphalt powder is less than 100 mesh.

[0057] In some embodiments, in step (2), the mass ratio of the asphalt powder to the template is (2-4): (6-8). By controlling the mass ratio of the asphalt powder to the template within this range, the two can be fully mixed, thereby forming a uniform and dense pore structure in the subsequent process; and the added amount of the nitrogen source accounts for 0.1% to 0.5% of the total mass of the asphalt powder, the template and the nitrogen source. The added amount of the nitrogen source should not be too high, otherwise it will cause the density and strength of the prepared carbon material to decrease, affecting its further application;

[0058] Preferably, the template comprises at least one of nano-magnesium oxide, block copolymer Pluronic F127, molecular sieve SBA-15, and silicon dioxide;

[0059] Preferably, the nitrogen source includes at least one of melamine, hexadecyltrimethylammonium chloride, and dicyanamide. The selected nitrogen source can not only provide nitrogen elements and be doped into the mesoporous carbon, which can effectively improve the conductive properties of the material, but also can serve as a template to assist in pore formation, which is beneficial to increase the specific surface area of ​​the mesoporous carbon material.

[0060] In some embodiments, in step (2), the microwave-assisted pre-oxidation treatment is carried out in an air atmosphere, the microwave power is ≥1500W, the temperature of the microwave-assisted pre-oxidation treatment is 150-250°C, and the pre-oxidation time is 15-35 minutes.

[0061] By pre-oxidizing the mixture of coal tar, template and nitrogen source with microwave-assisted technology, the pore structure of the mesoporous carbon material can be effectively improved, and oxygen-containing functional groups can be introduced into the surface and pore structure of the mesoporous carbon material. It can also effectively reduce the carbonization temperature, maintain the stability of the pore structure, and increase the specific surface area of ​​the mesoporous carbon material. The process takes a short time and is highly efficient.

[0062] In some embodiments, in step (3), the carbonization treatment is carried out in a nitrogen atmosphere with a nitrogen flow rate of 20 to 40 mL / min; the carbonization treatment temperature is 600 to 1000°C, the heating rate is 5 to 10°C / min, and the carbonization time is 1 to 3 hours.

[0063] In some embodiments, in step (4), the acidic solution includes at least one of a hydrochloric acid solution, a phosphoric acid solution, a sulfuric acid solution, and a nitric acid solution; and the concentration of the acidic solution is 1 to 3 mol / L. If the concentration of the acidic solution is too low, the template will not be completely removed and the pickling time will be too long; but if the concentration of the acidic solution is too high, the structure of the carbon material will be destroyed and the thermal stability will be reduced. Therefore, it is advantageous to control the concentration of the acidic solution within the range of 1 to 3 mol / L in the embodiment of the present invention.

[0064] And / or, the microwave-assisted pickling treatment is carried out in an air atmosphere, the microwave power is ≤300W, the temperature of the microwave-assisted pickling treatment is 30-50°C, and the pickling time is 5-15 minutes.

[0065] The embodiment of the present invention uses microwave-assisted technology for pickling, replacing traditional pickling processes such as filtration, stirring, and ultrasound, which can effectively solve problems such as incomplete template removal and environmental pollution, ensure the performance of the obtained mesoporous carbon material, and be environmentally friendly; and using microwave-assisted technology for pickling can shorten the pickling time and improve the pickling efficiency.

[0066] In some embodiments, in step (5), the washing agent used in the washing comprises at least one of water and ethanol;

[0067] And / or, the drying method is vacuum drying, the drying temperature is 40-60° C., and the drying time is 8-12 hours.

[0068] In some embodiments, in step (6), the activation medium used in the activation treatment is water vapor or carbon monoxide, and the flow rate of the activation medium is 5 to 15 mL / min;

[0069] And / or, the activation treatment is carried out in a nitrogen atmosphere with a nitrogen flow rate of 20 to 40 mL / min; the activation treatment temperature is 800 to 1000° C., the heating rate is 5 to 10° C. / min, and the activation time is 1 to 2 h.

[0070] By using water vapor or carbon monoxide as an activation medium to activate the material, a pore structure with more mesopore sizes can be obtained, effectively increasing the specific surface area of ​​the carbon material. The inventors have found through research that if the activation temperature is too high, the pore structure of the carbon material will collapse; but if the activation temperature is too low, the activation effect will be unsatisfactory and the specific surface area will not be high. Therefore, it is beneficial to control the activation temperature at 800-1000°C in the embodiment of the present invention.

[0071] In a second aspect, an embodiment of the present invention further provides a pitch-based nitrogen-doped functionalized mesoporous carbon, wherein the pitch-based nitrogen-doped functionalized mesoporous carbon is prepared by the method described in the first aspect.

[0072] In the third aspect, the embodiments of the present invention further propose an application of the asphalt-based nitrogen-doped functionalized mesoporous carbon as described in the second aspect in the field of new energy materials (such as: electrode materials or catalyst supports for fuel cells and supercapacitors, etc.).

[0073] The following are non-limiting examples and comparative examples of the present invention. It should be noted that the solutions in the comparative examples are not prior art and are provided solely for comparison with the solutions in the examples and are not intended to limit the present invention. Unless otherwise noted, the various raw materials used in the examples and comparative examples are conventional commercially available products or can be prepared by known methods.

[0074] Example 1

[0075] This embodiment provides a microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon, comprising the following steps:

[0076] (1) Weighing 100 g of deashed refined coal liquefaction pitch (softening point of about 120° C., quinoline insoluble matter <0.01%, China Shenhua Coal to Liquid Chemical Co., Ltd.), placing it in a crusher for 10 min, and screening the pitch powder through a 100-mesh standard sieve to obtain pitch powder with a particle size of <100 mesh;

[0077] (2) Weigh 10 g of the above-mentioned asphalt powder and nano-magnesium oxide powder in a mass ratio of 3:7, add 0.3% of melamine in total mass percentage, and mix evenly for 3 minutes using a mixing vibration ball mill; then take 3 g of the mixture, put it into a crucible, and place it in a microwave tube furnace in an air atmosphere at a power of 1500 W and a temperature of 200° C., and perform microwave-assisted pre-oxidation treatment for 20 minutes to obtain a pre-oxidation product;

[0078] (3) placing the pre-oxidation product obtained in step (2) in a high-temperature tube furnace and introducing nitrogen for protection at a nitrogen flow rate of 30 mL / min, heating the furnace to 800°C at a heating rate of 5°C / min, and carbonizing the furnace for 2 h to obtain a carbonized product;

[0079] (4) The carbonized product obtained in step (3) was placed in a 50 mL beaker, and 25 mL of a 2 mol / L hydrochloric acid solution was added to the beaker and stirred to form a slurry. The slurry was then placed in a low-power microwave oven and subjected to microwave-assisted pickling treatment at 300 W power and 40° C. in an air atmosphere for 10 min;

[0080] (5) The acid-washed product obtained in step (4) was washed several times with a 20% ethanol-water solution until the pH became neutral, and then vacuum-dried at 60° C. for 12 h;

[0081] (6) The dried product obtained in step (5) is placed in a high-temperature tubular furnace and nitrogen is introduced for protection at a nitrogen flow rate of 30 mL / min. At the same time, water vapor is used as an activation medium at a medium flow rate of 10 mL / min. The temperature is raised to 1000°C at a heating rate of 5°C / min and the activation treatment is performed for 1 hour to obtain asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0082] Figure 2 These are scanning electron microscope images of the pitch-based nitrogen-doped functionalized mesoporous carbon prepared in this example at different magnifications.

[0083] Figure 3 These are transmission electron micrographs of the pitch-based nitrogen-doped functionalized mesoporous carbon prepared in this example at different magnifications.

[0084] Figure 4 This is the EDS element mapping diagram of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in this example. It can be seen from the figure that it contains elements such as C, N, and O, indicating that the product prepared in this example has successfully incorporated nitrogen.

[0085] Figure 5 This is the X-ray diffraction spectrum of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in this example. As can be seen from the figure, the material has obvious (002) and (100 / 101) diffraction peaks, indicating that the obtained mesoporous carbon is an amorphous material.

[0086] Figure 6 This is the Raman spectrum of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in this embodiment. It can be seen from the figure that the material has obvious D and G peaks, and the ID / IG value is 1.102, indicating that the mesoporous carbon material has very high porosity and defect density.

[0087] Figure 7 This is the infrared spectrum of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in this embodiment. It can be seen from the figure that the material contains vibration peaks such as C=C, C=O, CN, CS, etc., which further indicates that the mesoporous carbon material contains elements such as C, N, O, and S.

[0088] Figure 8 This is the thermogravimetric curve of the pitch-based nitrogen-doped functionalized mesoporous carbon prepared in this embodiment. As can be seen from the figure, the mesoporous carbon material has significantly higher thermal stability.

[0089] Example 2

[0090] This embodiment provides a microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon, comprising the following steps:

[0091] (1) Weighing 100 g of deashed refined coal liquefaction pitch (softening point of about 120° C., quinoline insoluble matter <0.01%, China Shenhua Coal to Liquid Chemical Co., Ltd.), placing it in a crusher for 10 min, and screening the pitch powder through a 100-mesh standard sieve to obtain pitch powder with a particle size of <100 mesh;

[0092] (2) 10 g of the above-mentioned asphalt powder and Pluronic F127 were weighed in a mass ratio of 3:7, and 0.5% of dicyandiamide was added thereto, and the mixture was uniformly mixed using a mixing vibration ball mill for 3 minutes; then 3 g of the mixture was taken, placed in a crucible, and placed in a microwave tube furnace under air atmosphere at 1500 W power and 250° C. for 15 minutes to obtain a pre-oxidized product;

[0093] (3) placing the pre-oxidation product obtained in step (2) in a high-temperature tube furnace and introducing nitrogen for protection at a nitrogen flow rate of 30 mL / min, heating the furnace to 800°C at a heating rate of 5°C / min, and carbonizing the furnace for 3 hours to obtain a carbonized product;

[0094] (4) The carbonized product obtained in step (3) was placed in a 50 mL beaker, and 25 mL of a 2 mol / L sulfuric acid solution was added to the beaker and stirred to form a slurry. The slurry was then placed in a low-power microwave oven and subjected to microwave-assisted pickling treatment for 10 min at 250 W power and 40° C. in an air atmosphere.

[0095] (5) The acid-washed product obtained in step (4) was washed several times with a 20% ethanol-water solution until the pH became neutral, and then vacuum-dried at 60° C. for 12 h;

[0096] (6) The dried product obtained in step (5) is placed in a high-temperature tubular furnace and nitrogen is introduced for protection at a nitrogen flow rate of 30 mL / min. At the same time, water vapor is used as an activation medium at a medium flow rate of 5 mL / min. The temperature is raised to 1000°C at a heating rate of 5°C / min and the activation treatment is performed for 1 hour to obtain asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0097] Example 3

[0098] This embodiment provides a microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon, comprising the following steps:

[0099] (1) Weighing 100 g of deashed refined coal liquefaction pitch (softening point of about 120° C., quinoline insoluble matter <0.01%, China Shenhua Coal to Liquid Chemical Co., Ltd.), placing it in a crusher for 10 min, and screening the pitch powder through a 100-mesh standard sieve to obtain pitch powder with a particle size of <100 mesh;

[0100] (2) Weigh 10 g of the above-mentioned asphalt powder and molecular sieve SBA-15 in a mass ratio of 2:8, add 0.5% of hexadecyltrimethylammonium chloride to the mixture, and mix them evenly for 3 minutes using a mixing vibration ball mill; then take 3 g of the mixture, put it into a crucible, and place it in a microwave tube furnace under air atmosphere at 1500 W power and 250°C, and perform microwave-assisted pre-oxidation treatment for 20 minutes to obtain a pre-oxidation product;

[0101] (3) placing the pre-oxidation product obtained in step (2) in a high-temperature tube furnace and introducing nitrogen for protection at a nitrogen flow rate of 30 mL / min, heating the furnace to 1000°C at a heating rate of 5°C / min, and carbonizing the furnace for 2 h to obtain a carbonized product;

[0102] (4) The carbonized product obtained in step (3) was placed in a 50 mL beaker, and 25 mL of a 1 mol / L phosphoric acid solution was added to the beaker and stirred to form a slurry. The slurry was then placed in a low-power microwave oven and subjected to microwave-assisted pickling treatment for 5 min at 300 W power and 40° C. in an air atmosphere.

[0103] (5) The acid-washed product obtained in step (4) was washed several times with a 5% ethanol-water solution until the pH became neutral, and then vacuum-dried at 60° C. for 12 h;

[0104] (6) The dried product obtained in step (5) is placed in a high-temperature tubular furnace and nitrogen is introduced for protection at a nitrogen flow rate of 30 mL / min. At the same time, water vapor is used as an activation medium at a medium flow rate of 5 mL / min. The temperature is raised to 1000°C at a heating rate of 5°C / min and the activation treatment is performed for 2 hours to obtain asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0105] Comparative Example 1

[0106] This comparative example provides a method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon, comprising the following steps:

[0107] (1) Weighing 100 g of deashed refined coal liquefaction pitch (softening point of about 120° C., quinoline insoluble matter <0.01%, China Shenhua Coal to Liquid Chemical Co., Ltd.), placing it in a crusher for 10 min, and screening the pitch powder through a 100-mesh standard sieve to obtain pitch powder with a particle size of <100 mesh;

[0108] (2) Weigh 10 g of the above-mentioned asphalt powder and nano-magnesium oxide powder in a mass ratio of 3:7, add 0.3% of melamine, and mix them evenly in a mixing vibration ball mill for 3 minutes;

[0109] (3) placing the mixture obtained in step (2) in a high-temperature tube furnace and introducing nitrogen for protection at a nitrogen flow rate of 30 mL / min, heating the mixture to 800°C at a heating rate of 5°C / min, and carbonizing the mixture for 2 h to obtain a carbonized product;

[0110] (4) The carbonized product obtained in step (3) was placed in a 50 mL beaker, and 25 mL of a 2 mol / L hydrochloric acid solution was added to the beaker, stirred and mixed, and acid-washed for 60 min;

[0111] (5) The acid-washed product obtained in step (4) was washed several times with a 20% ethanol-water solution until the pH became neutral, and then vacuum-dried at 60° C. for 12 h;

[0112] (6) The dried product obtained in step (5) is placed in a high-temperature tubular furnace and nitrogen is introduced for protection at a nitrogen flow rate of 30 mL / min. At the same time, water vapor is used as an activation medium at a medium flow rate of 10 mL / min. The temperature is raised to 1000°C at a heating rate of 5°C / min and the activation treatment is performed for 1 hour to obtain asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0113] Figure 9 The nitrogen adsorption-desorption isotherms of the mesoporous carbon obtained in Example 1 and Comparative Example 1 of the present invention are shown in the figure. As can be seen from the figure, the specific surface area of ​​the mesoporous carbon obtained in Comparative Example 1 is only 468.90 m 3 / g. In comparison, the mesoporous carbon prepared by the method of Example 1 of the present invention has a higher specific surface area, reaching 1162.23m 3 / g.

[0114] Figure 10 This is a pore size distribution curve diagram of the mesoporous carbon prepared in Example 1 of the present invention and Comparative Example 1. It can be seen from the figure that the average pore diameter of the mesoporous carbon prepared in Comparative Example 1 reaches 24.80 nm. In comparison, the pore diameter of the mesoporous carbon prepared in Example 1 of the present invention is significantly smaller, with an average pore diameter of only 8.46 nm, further indicating that it has a higher specific surface area.

[0115] Comparative Example 2

[0116] This comparative example provides a method for preparing pitch-based mesoporous carbon, comprising the following steps:

[0117] (1) Weighing 100 g of deashed refined coal liquefaction pitch (softening point of about 120° C., quinoline insoluble matter <0.01%, China Shenhua Coal to Liquid Chemical Co., Ltd.), placing it in a crusher for 10 min, and screening the pitch powder through a 100-mesh standard sieve to obtain pitch powder with a particle size of <100 mesh;

[0118] (2) Weighing 10 g of the above-mentioned asphalt powder and nano-magnesium oxide powder in a mass ratio of 3:7, and uniformly mixing them using a mixing vibration ball mill for 3 minutes; then taking 3 g of the mixture, placing it in a crucible, and placing it in a microwave tube furnace, in an air atmosphere, at a power of 1500 W and a temperature of 200° C., and performing microwave-assisted pre-oxidation treatment for 20 minutes to obtain a pre-oxidation product;

[0119] (3) placing the pre-oxidation product obtained in step (2) in a high-temperature tube furnace and introducing nitrogen for protection at a nitrogen flow rate of 30 mL / min, heating the furnace to 800°C at a heating rate of 5°C / min, and carbonizing the furnace for 2 h to obtain a carbonized product;

[0120] (4) The carbonized product obtained in step (3) was placed in a 50 mL beaker, and 25 mL of a 2 mol / L hydrochloric acid solution was added to the beaker, stirred and mixed, and acid-washed for 60 min;

[0121] (5) The acid-washed product obtained in step (4) was washed several times with a 20% ethanol-water solution until the pH became neutral, and then vacuum-dried at 60° C. for 12 h;

[0122] (6) The dried product obtained in step (5) is placed in a high-temperature tubular furnace and nitrogen is introduced for protection at a nitrogen flow rate of 30 mL / min. At the same time, water vapor is used as an activation medium at a medium flow rate of 10 mL / min. The temperature is raised to 1000°C at a heating rate of 5°C / min and the activation treatment is performed for 1 hour to obtain asphalt-based mesoporous carbon.

[0123] The mesoporous carbon prepared in Example 1 and Comparative Example 2 of the present invention was used as a carrier of hydrogen fuel cell catalyst, and Pt nanoparticles were loaded to prepare electrode catalysts. The conductivity of the obtained catalysts was tested, and the results were as follows: Figure 11 The test process is as follows: high O2 is introduced into 0.1 mol / L HCIO4 aqueous solution, and the solution is purged for 30 minutes to saturate the oxidation reaction; in a three-electrode system, the ring electrode rotates at 1500 r / min and the electrode is heated at 0.3-1.2 V. RHE Scan forward at 5mV / s within the scanning range and record the polarization curve and 0.9V RHE When the current density is Figure 11 It can be seen that the catalyst prepared with the mesoporous carbon as the carrier in Example 1 has a high RHE 4.42mA / cm 2 Current density, while Comparative Example 2 at 0.9V RHE Only 2.15mA / cm 2 The current density shows that the nitrogen-doped mesoporous carbon has better conductivity, which makes the corresponding catalyst have stronger catalytic performance.

[0124] Comparative Example 3

[0125] This comparative example provides a method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon, comprising the following steps:

[0126] (1) Weighing 100 g of deashed refined coal liquefaction pitch (softening point of about 120° C., quinoline insoluble matter <0.01%, China Shenhua Coal to Liquid Chemical Co., Ltd.), placing it in a crusher for 10 min, and screening the pitch powder through a 100-mesh standard sieve to obtain pitch powder with a particle size of <100 mesh;

[0127] (2) Weigh 10 g of the above-mentioned asphalt powder and nano-magnesium oxide powder in a mass ratio of 3:7, add 0.3% of melamine in total mass percentage, and mix evenly for 3 minutes using a mixing vibration ball mill; then take 3 g of the mixture, put it into a crucible, and place it in a microwave tube furnace in an air atmosphere at a power of 1500 W and a temperature of 200° C., and perform microwave-assisted pre-oxidation treatment for 20 minutes to obtain a pre-oxidation product;

[0128] (3) placing the pre-oxidation product obtained in step (2) in a high-temperature tube furnace and introducing nitrogen for protection at a nitrogen flow rate of 30 mL / min, heating the furnace to 800°C at a heating rate of 5°C / min, and carbonizing the furnace for 2 h to obtain a carbonized product;

[0129] (4) The carbonized product obtained in step (3) was placed in a 50 mL beaker, and 25 mL of a 2 mol / L hydrochloric acid solution was added to the beaker and stirred to form a slurry. The slurry was then placed in a low-power microwave oven and subjected to microwave-assisted pickling treatment at 300 W power and 40° C. in an air atmosphere for 10 min.

[0130] (5) The acid-washed product obtained in step (4) was washed several times with a 20% ethanol-water solution until the pH became neutral, and then vacuum-dried at 60° C. for 12 h to obtain asphalt-based nitrogen-doped functionalized mesoporous carbon.

[0131] Figure 12 This is a scanning electron microscope image of the mesoporous carbon prepared in Comparative Example 3, compared with the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in Example 1 ( Figure 2 ), and its surface does not have a fine and uniform pore structure.

[0132] Figure 13 The nitrogen adsorption-desorption isotherms of the mesoporous carbon obtained in Example 1 and Comparative Example 3 of the present invention are shown in the figure. As can be seen from the figure, the specific surface area of ​​the mesoporous carbon obtained in Comparative Example 3 is only 274.35 m 3 / g, while the specific surface area of ​​the mesoporous carbon prepared in Example 1 of the present invention is as high as 1162.23m 3 / g.

[0133] The performance of the mesoporous carbons prepared in the above examples and comparative examples was tested, and the results are shown in Table 1.

[0134] Table 1

[0135] <![CDATA[Specific surface area (m 3 / g)]]> Average pore size (nm) Thermal stability (℃) <![CDATA[Current density (mA / cm 2 )]]> Example 1 1162.23 8.46 550 4.42 Example 2 1033.61 9.02 550 — Example 3 986.45 10.84 545 — Comparative Example 1 468.90 24.80 485 1.48 Comparative Example 2 944.67 13.06 540 2.15 Comparative Example 3 274.35 38.62 440 0.88

[0136] It can be seen from Table 1 that compared with the mesoporous carbon prepared in Comparative Examples 1-3, the pitch-based nitrogen-doped functionalized mesoporous carbon prepared by the method of the embodiment of the present invention has a higher specific surface area and better thermal stability and conductivity.

[0137] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0138] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon, characterized in that: The steps include: (1) crushing deashed refined coal liquefaction pitch to obtain pitch powder; wherein the deashed refined coal liquefaction pitch has a softening point of 100 to 130° C. and contains quinoline insoluble matter less than 0.01%; (2) After mixing the asphalt powder with a template and a nitrogen source, performing microwave-assisted pre-oxidation treatment; wherein the mass ratio of the asphalt powder to the template is (2-4):(6-8), and the amount of the nitrogen source added accounts for 0.1% to 0.5% of the total mass of the asphalt powder, the template and the nitrogen source; the template comprises at least one of nano-magnesium oxide, block copolymer Pluronic F127, molecular sieve SBA-15, and silicon dioxide; and the nitrogen source comprises at least one of melamine, hexadecyltrimethylammonium chloride, and dicyanamide; (3) carbonizing the pre-oxidation product obtained in step (2); (4) adding an acidic solution to the carbonized product obtained in step (3) and stirring and mixing to form a slurry; then subjecting the slurry to a microwave-assisted pickling treatment; wherein the acidic solution comprises at least one of a hydrochloric acid solution, a phosphoric acid solution, a sulfuric acid solution, and a nitric acid solution, and the concentration of the acidic solution is 1 to 3 mol / L; (5) washing the acid-washed product obtained in step (4) until the pH is neutral, and then drying it; (6) Activating the dried product obtained in step (5) to obtain the asphalt-based nitrogen-doped functionalized mesoporous carbon; wherein the activation medium used in the activation treatment is water vapor or carbon monoxide, and the flow rate of the activation medium is 5 to 15 mL / min.

2. The microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon according to claim 1, characterized in that: In the step (1), the crushing treatment time is 5 to 15 minutes; And / or, the particle size of the asphalt powder is less than 100 mesh.

3. The microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon according to claim 1, characterized in that: In the step (2), the microwave-assisted pre-oxidation treatment is carried out in an air atmosphere, the microwave power is ≥1500W, the temperature of the microwave-assisted pre-oxidation treatment is 150-250°C, and the pre-oxidation time is 15-35 minutes.

4. The microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon according to claim 1, characterized in that: In the step (3), the carbonization treatment is carried out in a nitrogen atmosphere with a nitrogen flow rate of 20 to 40 mL / min; the carbonization treatment temperature is 600 to 1000° C., the heating rate is 5 to 10° C. / min, and the carbonization time is 1 to 3 hours.

5. The microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon according to claim 1, characterized in that: In the step (4), the microwave-assisted pickling treatment is carried out in an air atmosphere, the microwave power is ≤300W, the temperature of the microwave-assisted pickling treatment is 30-50°C, and the pickling time is 5-15 minutes.

6. The microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon according to claim 1, characterized in that: In the step (5), the washing agent used in the washing comprises at least one of water and ethanol; And / or, the drying method is vacuum drying, the drying temperature is 40-60° C., and the drying time is 8-12 hours.

7. The microwave-assisted method for preparing pitch-based nitrogen-doped functionalized mesoporous carbon according to claim 1, characterized in that: In the step (6), the activation treatment is carried out in a nitrogen atmosphere with a nitrogen flow rate of 20 to 40 mL / min; the temperature of the activation treatment is 800 to 1000° C., the heating rate is 5 to 10° C. / min, and the activation time is 1 to 2 h.

8. A pitch-based nitrogen-doped functionalized mesoporous carbon, characterized in that: The asphalt-based nitrogen-doped functionalized mesoporous carbon is prepared by the method according to any one of claims 1 to 7.

9. Use of the asphalt-based nitrogen-doped functionalized mesoporous carbon as claimed in claim 8 in the field of new energy materials.

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