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

Abstract

The invention discloses a microwave-assisted asphalt-based nitrogen-doped functionalized mesoporous carbon preparation method, which comprises: (1) carrying out crushing treatment on ash-removed refined coal liquefaction asphalt to obtain asphalt powder; (2) mixing the asphalt powder with a template agent and a nitrogen source, and carrying out microwave-assisted pre-oxidation treatment; (3) carrying out carbonization treatment on the pre-oxidized product; (4) adding an acidic solution into the carbonized product, and stirring and mixing to form slurry; then carrying out microwave-assisted pickling treatment on the slurry; (5) washing the acid pickling product until the pH value is neutral, and then carrying out drying treatment; and (6) activating the dried product to obtain the asphalt-based nitrogen-doped functionalized mesoporous carbon. According to the method, the carbonization temperature is reduced through the microwave-assisted technology, the specific surface area of the product is increased, the acid pickling process is simplified, and the problems that in the prior art, the pore structure of a mesoporous carbon material is prone to collapse and damage, and a template is not thoroughly removed can be effectively solved.

Description

Technical Field

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

[0002] High-stability mesoporous carbon materials have unique pore size distribution and large specific surface area, and are widely used in the fields of fuel cells, electrode materials for supercapacitors, and catalyst carriers. The preparation of carbon materials with cheap and abundant coal-based raw materials meets my country's current energy and environmental protection needs. Coal liquefaction pitch has the characteristics of high carbon content, good thermal stability, and high viscosity, and is an important carbon source for the preparation of mesoporous carbon.

[0003] There are many traditional methods for preparing coal-based mesoporous carbon, but there are problems such as poor stability, uneven pore size distribution, and low synthesis efficiency, which limit its practical application effect. For example: In the prior art, coal-based mesoporous carbon is prepared by pyrolysis. Although the process is simple and easy to achieve large-scale production, the quality of the obtained mesoporous carbon product is poor, and the specific surface area and porosity are relatively low; while the chemical and chemical activation methods can significantly increase the specific surface area and pore structure of carbon materials, but increase the difficulty and cost of environmental treatment. At present, the most widely used methods are hard template and soft template methods for preparing mesoporous carbon, which can accurately control the pore size distribution and pore structure. However, the template method carbonization activation and acid washing process are complex, long, and inefficient, and the template is not completely removed, and the removal process is also prone to pollution. This inefficient and high-cost synthesis method is not conducive to large-scale production and other problems; and the high-temperature carbonization step involved in the synthesis process is prone to damage to the pore structure, affecting the performance of the mesoporous carbon material. Therefore, it is urgent to develop an efficient, low-cost and environmentally friendly synthesis method to ensure that the pore structure of mesoporous carbon is uniform, stable and controllable. Summary of the invention

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

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

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

[0008] (3) subjecting the pre-oxidation product obtained in step (2) to carbonization treatment;

[0009] (4) adding an acidic solution to the carbonized product obtained in step (3), stirring and mixing, 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 <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, hexadecyltrimethylammonium chloride and dicyandiamide.

[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 15-35min.

[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 5-15min.

[0022] In some embodiments, in step (5), the washing agent used in the washing includes 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 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.

[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 provides a microwave-assisted method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon. The method uses microwaves to pre-oxidize the carbon precursor, the template agent, and the nitrogen source mixture, so that the three are evenly mixed, and the specific surface area of ​​the mesoporous carbon product can be effectively increased. At the same time, it is also beneficial to reduce the carbonization temperature, thereby solving the problem that the pore structure of the carbon material is easy to collapse and damage; and by using microwave treatment means for pickling, replacing traditional filtering, stirring and other processes, it can effectively solve 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 elements can be doped into the mesoporous carbon while forming pores, effectively improving the conductive properties of the material. The method of the present invention has a simple preparation process, is easy to operate, has a short synthesis time, high efficiency, and low cost, which significantly reduces the synthesis cost of the mesoporous carbon material and improves the production efficiency. The prepared mesoporous carbon material has good comprehensive performance and meets its application needs 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 preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance according to an embodiment of the present invention.

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

[0032] Figure 3 Transmission electron microscopy images 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] Fig. 9 The nitrogen adsorption-desorption isotherms of the mesoporous carbons prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0039] Fig.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] Fig.11 The conductive performance test diagram of the mesoporous carbon prepared in Example 1 and Comparative Example 2 of the present invention.

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

[0042] Fig.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] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0044] Where values ​​are described herein as a range, 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 a specific sub-range is explicitly stated.

[0045] Herein, the words "comprises" and "includes" and variations thereof mean that other elements or integers which are permitted but not specifically described may be included.

[0046] In this article, the term "and / or" is merely a term used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: 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 asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance, comprising the following steps:

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

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

[0050] (3) subjecting the pre-oxidation product obtained in step (2) to carbonization treatment;

[0051] (4) adding an acidic solution to the carbonized product obtained in step (3), stirring and mixing, 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 phenomenon of filamentation 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; and the inventors have also found that when the asphalt with too high a quinoline insoluble content is prepared, the strength, density and antioxidant performance will decrease. Therefore, in the embodiment of the present invention, the softening point and quinoline insoluble content of the coal liquefaction pitch are controlled within the above range;

[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, it is possible to ensure that the two are fully mixed, thereby forming a uniform and dense pore structure in the subsequent process; and the amount of the nitrogen source added is 0.1% to 0.5% of the total mass of the asphalt powder, the template and the nitrogen source. The amount of the nitrogen source added 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 dicyandiamide. The selected nitrogen source can not only provide nitrogen elements and be doped into the mesoporous carbon to effectively improve the conductivity of the material, but also 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 15-35min.

[0061] Pre-oxidation treatment of a mixture of coal tar pitch, template and nitrogen source using microwave-assisted technology can effectively improve the pore structure of the mesoporous carbon material, introduce oxygen-containing functional groups into the surface and pore structure of the mesoporous carbon material, and 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 hydrochloric acid solution, phosphoric acid solution, sulfuric acid solution, and 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 in 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 5-15min.

[0065] The embodiment of the present invention uses microwave-assisted technology for pickling, which replaces traditional pickling processes such as filtration, stirring, and ultrasound, and can effectively solve the problems of 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 includes 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 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.

[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 advantageous for the embodiment of the present invention to control the activation temperature at 800-1000°C.

[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 carriers 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 schemes of the comparative examples are not prior art and are only provided for comparison with the schemes of the embodiments and are not intended to limit the present invention. Unless otherwise specified, the various raw materials used in the embodiments and comparative examples are conventional commercial products or can be prepared by known methods.

[0074] Example 1

[0075] This embodiment provides a method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon by microwave-assisted method, 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 of crushing treatment, and screening the asphalt powder through a 100-mesh standard sieve to obtain asphalt 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, and perform microwave-assisted pre-oxidation treatment for 20 minutes at 1500 W power and 200° C. in an air atmosphere to obtain a pre-oxidation product;

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

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

[0080] (5) washing the acid-washed product obtained in step (4) with a 20% ethanol-water solution for multiple times until the pH becomes neutral, and then vacuum drying 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 increased 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 The scanning electron microscope images of the asphalt-based nitrogen-doped functionalized mesoporous carbon prepared in this example at different magnifications are shown.

[0083] Figure 3 Transmission electron microscopy images of the asphalt-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. It can be seen from the figure that 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. It can be seen from the figure that the mesoporous carbon material has obviously higher thermal stability.

[0089] Example 2

[0090] This embodiment provides a method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon by microwave-assisted method, 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 of crushing treatment, and screening the asphalt powder through a 100-mesh standard sieve to obtain asphalt powder with a particle size of <100 mesh;

[0092] (2) Weigh 10 g of the above-mentioned asphalt powder and Pluronic F127 in a mass ratio of 3:7, add 0.5% of dicyandiamide 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, and perform microwave-assisted pre-oxidation treatment for 15 minutes at 1500 W power and 250° C. in an air atmosphere to obtain a pre-oxidation product;

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

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

[0095] (5) washing the acid-washed product obtained in step (4) with a 20% ethanol-water solution for multiple times until the pH becomes neutral, and then vacuum drying 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 increased 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 method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon by microwave-assisted method, 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 of crushing treatment, and screening the asphalt powder through a 100-mesh standard sieve to obtain asphalt 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 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, and perform microwave-assisted pre-oxidation treatment for 20 minutes at 1500 W power and 250° C. in an air atmosphere to obtain a pre-oxidation product;

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

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

[0103] (5) washing the acid-washed product obtained in step (4) with a 5% ethanol-water solution for multiple times until the pH becomes neutral, and then vacuum drying 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 increased to 1000°C at a heating rate of 5°C / min and 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 asphalt-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 of crushing treatment, and screening the asphalt powder through a 100-mesh standard sieve to obtain asphalt 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 for 3 minutes using a mixing vibration ball mill;

[0109] (3) placing the mixture obtained in step (2) in a high-temperature tube furnace, introducing nitrogen for protection, with a nitrogen flow rate of 30 mL / min, heating to 800° C. at a heating rate of 5° C. / min, and carbonizing 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) washing the acid-washed product obtained in step (4) with a 20% ethanol-water solution for multiple times until the pH becomes neutral, and then vacuum drying 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 increased 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] Fig. 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 1162.23 m 3 / g.

[0114] Fig.10 The pore size distribution curve of the mesoporous carbon prepared in Example 1 of the present invention and Comparative Example 1 is shown. It can be seen from the figure that the average pore size of the mesoporous carbon prepared in Comparative Example 1 reaches 24.80 nm. In comparison, the pore size of the mesoporous carbon prepared in Example 1 of the present invention is significantly smaller, with an average pore size 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 asphalt-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 of crushing treatment, and screening the asphalt powder through a 100-mesh standard sieve to obtain asphalt powder with a particle size of <100 mesh;

[0118] (2) Weigh 10 g of the above-mentioned asphalt powder and nano-magnesium oxide powder in a mass ratio of 3:7, 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, and perform microwave-assisted pre-oxidation treatment for 20 minutes at 1500 W power and 200° C. in an air atmosphere to obtain a pre-oxidation product;

[0119] (3) placing the pre-oxidation product obtained in step (2) in a high-temperature tube furnace, introducing nitrogen for protection, with a nitrogen flow rate of 30 mL / min, heating to 800° C. at a heating rate of 5° C. / min, and carbonizing 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) washing the acid-washed product obtained in step (4) with a 20% ethanol-water solution for multiple times until the pH becomes neutral, and then vacuum drying 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 increased to 1000°C at a heating rate of 5°C / min and 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 a hydrogen fuel cell catalyst, and Pt nanoparticles were loaded to prepare an electrode catalyst. The conductivity of the obtained catalyst was tested, and the results were as follows: Fig.11 The test process is as follows: add 0.1mol / L HCIO 4 The aqueous solution is filled with high oxygen 2 , purge for 30min to saturate the oxidation; in the three-electrode system, the ring electrode speed is 1500r / min, at 0.3~1.2V RHE In the scanning range, scan forward at 5mV / s and record the polarization curve and 0.9V RHE The current density is Fig.11 It can be seen that the catalyst prepared with the mesoporous carbon as the carrier in Example 1 has a RHE 4.42mA / cm 2 Current density, while Comparative Example 2 at 0.9V RHE Only 2.15mA / cm 2The 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 asphalt-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 of crushing treatment, and screening the asphalt powder through a 100-mesh standard sieve to obtain asphalt 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, and perform microwave-assisted pre-oxidation treatment for 20 minutes at 1500 W power and 200° C. in an air atmosphere to obtain a pre-oxidation product;

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

[0129] (4) placing the carbonized product obtained in step (3) into a 50 mL beaker, adding 25 mL of a 2 mol / L hydrochloric acid solution into the beaker, stirring to form a slurry, and then placing the slurry in a low-power microwave oven, in an air atmosphere, at a power of 300 W and a temperature of 40° C., for microwave-assisted pickling 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] Fig.12 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] Fig.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 1162.23 m 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 asphalt-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" etc. 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 representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

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

Claims

1. A method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance, characterized in that: The steps include: (1) crushing the deashed refined coal liquefaction asphalt to obtain asphalt powder; (2) mixing the asphalt powder with a template and a nitrogen source, and then performing a microwave-assisted pre-oxidation treatment; (3) subjecting the pre-oxidation product obtained in step (2) to carbonization treatment; (4) adding an acidic solution to the carbonized product obtained in step (3), stirring and mixing, to form a slurry; Then, the slurry is subjected to microwave-assisted pickling treatment; (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.

2. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance according to claim 1, characterized in that: In the 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%; And / or, the crushing process takes 5 to 15 minutes; And / or, the particle size of the asphalt powder is less than 100 mesh.

3. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance according to claim 1, characterized in that: In the 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; Preferably, the template comprises at least one of nano magnesium oxide, block copolymer Pluronic F127, molecular sieve SBA-15, and silicon dioxide; Preferably, the nitrogen source includes at least one of melamine, hexadecyltrimethylammonium chloride and dicyandiamide.

4. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance 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 15-35min.

5. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance 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 temperature of the carbonization treatment is 600 to 1000° C., the heating rate is 5 to 10° C. / min, and the carbonization time is 1 to 3 hours.

6. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance according to claim 1, characterized in that: In the 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; 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 5-15min.

7. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance according to claim 1, characterized in that: In the step (5), the washing agent used for washing includes 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.

8. The method for preparing asphalt-based nitrogen-doped functionalized mesoporous carbon with microwave assistance according to claim 1, characterized in that: In the 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; And / or, 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.

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

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

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