High-layer spacing porous carbon material based on coal pre-oxidation treatment and preparation method of high-layer spacing porous carbon material

Abstract

The invention belongs to the technical field of carbon materials, and relates to a coal pre-oxidation treatment-based high-layer spacing porous carbon material and a preparation method thereof.A large number of oxygen-containing functional groups are constructed in coal through low-temperature pre-oxidation, and a cross-linked structure is constructed through the oxygen-containing functional groups in the coal low-temperature pyrolysis process; free movement, stacking and growth of aromatic lamellas are inhibited, a graphitization process of a carbon material is hindered, a foundation is laid for improvement of interlayer spacing, carbon is activated and etched by adopting excessive carbonate with relatively weak corrosivity, a large number of graded pore structures are generated, activated carbon with high specific surface area is generated, an oxygen-containing functional group structure generated by coal pre-oxidation is generated, and the carbon material is prepared. And uniform generation of subsequent pore structures is also facilitated. The coal-based carbon material obtained by coupling pre-oxidation with medium-temperature carbonate activation has higher interlayer spacing and specific surface area, and has a hierarchical porous structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon materials, and relates to a high interlayer spacing porous carbon material based on coal pre-oxidation treatment and a preparation method thereof. Background Art

[0002] With the accelerating advancement of the global industrialization process and the continuous growth of the population, the social demand for energy shows an exponential upward trend. The over-exploitation and consumption of traditional fossil fuels such as coal, oil, and natural gas not only exacerbate the energy supply tension but also bring serious environmental pollution and climate change problems. In this context, the development of renewable energy and the improvement of energy conversion efficiency have become the core issues of the global energy strategy, attracting extensive attention from the scientific research community, the industrial sector, and policymakers.

[0003] Among the numerous studies on renewable energy and high-efficiency energy materials, coal-based porous carbon materials stand out due to their unique physical and chemical properties. As a fossil resource with rich reserves and wide distribution, coal can be transformed into porous carbon materials through specific processes, which not only realizes the high-value utilization of coal resources but also endows the materials with excellent adsorption properties, electrochemical properties, and catalytic activities, showing great application potential in multiple energy fields such as supercapacitors, lithium-ion batteries, energy storage materials, gas separation and purification, and catalytic reaction carriers. Especially its porous structure provides channels for the rapid transport of ions and molecules, significantly improving the energy storage and conversion efficiency of the materials.

[0004] However, traditional methods for preparing coal-based porous carbon materials, such as physical activation methods (steam, carbon dioxide activation) and chemical activation methods (using activators such as KOH, ZnCl2, etc.), while achieving high performance of the materials, are also accompanied by a series of environmental and economic problems. Physical activation methods usually require high-temperature conditions, with high energy consumption and low efficiency; while chemical activation methods may produce a large amount of acid- and alkali-containing wastewater, which is prone to environmental pollution if not properly treated. At the same time, the high cost of activators also limits the large-scale application of this technology. In addition, the strong corrosive chemicals used in the activation process may also damage the production equipment, increasing the maintenance cost.

[0005] In summary, the existing technologies use alkalis with relatively strong alkalinity (such as NaOH, KOH, etc.), which have relatively large corrosivity to equipment and complex subsequent wastewater treatment processes; they can obtain activated carbon with a high specific surface area, but have a small interlayer spacing and a low oxygen doping amount. Therefore, in the face of increasingly stringent environmental protection requirements and energy transformation needs, seeking a more effective and greener method to prepare high-performance coal-based porous carbon materials has become one of the current research hotspots. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a high-layer-spacing porous carbon material based on coal pre-oxidation treatment and a preparation method thereof. By pre-oxidizing coal and activating it with a carbonate with relatively weak corrosiveness, a porous activated carbon with a large layer spacing and a high specific surface area is obtained.

[0007] The present invention is realized through the following technical solutions: A preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment, comprising: After the pretreated coal sample is subjected to low-temperature pre-oxidation treatment in an oxidizing atmosphere, the pre-oxidized coal sample is mixed with a carbonate, and then the mixed sample is subjected to high-temperature activation treatment in an inert atmosphere to obtain a high-layer-spacing porous carbon material based on coal pre-oxidation treatment.

[0008] Preferably, the pretreatment process of the coal is as follows: The coal is washed with 1-3 mol / L hydrochloric acid, stirred at 45-60 °C for 1-3 h, washed with deionized water until neutral, and dried for later use.

[0009] Preferably, the oxidizing atmosphere is at least one of oxygen and air.

[0010] Preferably, the specific process of the low-temperature pre-oxidation treatment is as follows: The pretreated coal sample is heated to 200-350 °C in an oxidizing atmosphere, kept warm for 1-3 h, and then cooled to room temperature to obtain a pre-oxidized coal sample.

[0011] Preferably, the carbonate is at least one of Na2CO3 and K2CO3.

[0012] Preferably, the mass ratio of the pretreated coal sample to the carbonate is 1:1-1:5.

[0013] Preferably, the specific process of the high-temperature activation treatment is as follows: The mixed sample of the pre-oxidized coal sample and the carbonate is heated to 700-900 °C in an inert atmosphere, kept warm for 1-3 h, and then cooled to room temperature in an inert atmosphere to obtain a high-layer-spacing porous carbon material based on coal pre-oxidation treatment.

[0014] Preferably, nitrogen or argon is used in the inert atmosphere.

[0015] Preferably, the sample after the high-temperature activation treatment is subjected to acid washing and ash removal, washed with water until neutral, and dried at 90-120 °C to obtain a high-layer-spacing porous carbon material based on coal pre-oxidation treatment.

[0016] A high-layer-spacing porous carbon material based on coal pre-oxidation treatment, prepared by the preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment described above.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a high-layer-spacing coal-based hierarchical porous carbon material and a preparation method thereof. By using low-temperature pre-oxidation to construct a large number of oxygen-containing functional groups in coal, a cross-linked structure is constructed during the low-temperature pyrolysis of coal through these oxygen-containing functional groups, inhibiting the free movement, stacking and growth of aromatic lamellae, hindering the graphitization process of the carbon material, and laying a foundation for the improvement of the layer spacing. Then, by using an excessive amount of carbonate with weak corrosiveness to activate and etch carbon, a large number of hierarchical pore structures are generated, and activated carbon with a high specific surface area is produced. The oxygen-containing functional group structure generated by the pre-oxidation of coal is also conducive to the uniform generation of subsequent pore structures. Through the coupling of pre-oxidation and medium-temperature carbonate activation, the coal-based carbon material obtained by the present invention has a higher layer spacing, specific surface area, and hierarchical porous structure.

[0018] Furthermore, the present invention prepares a coal-based porous carbon material by the method of pre-oxidation first and then activation. The present invention embodies many advantages of chemical activation (such as uniform morphology, large specific surface area, high porosity, and high carbon yield). By pre-oxidation, the layer spacing of the porous carbon can be increased, and it has better energy storage characteristics, and high-performance coal-based porous carbon can be obtained under low pollution conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a specific surface area and pore structure distribution diagram of the material prepared in Example 1, where (a) is the nitrogen adsorption-desorption isotherm and (b) is the pore size distribution diagram; Figure 2 It is a high-resolution transmission electron microscope image of the material prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0022] The present invention (1) constructs a large number of oxygen-containing functional groups in coal by using low-temperature pre-oxidation, and constructs a cross-linked structure during the low-temperature pyrolysis of coal through these oxygen-containing functional groups, inhibits the free movement, stacking and growth of aromatic lamellae, hinders the graphitization process of carbon materials, and lays a foundation for the increase of the layer spacing. (2) Activates and etches carbon with a weakly corrosive excess carbonate at 700-900 °C to generate a large number of hierarchical pore structures and produce activated carbon with a high specific surface area. The oxygen-containing functional group structure generated by coal pre-oxidation is also conducive to the uniform generation of subsequent pore structures.

[0023] The specific implementation method is as follows: in the range of 200-350 °C, use air, oxygen or a mixture of the two to oxidize pulverized coal particles for 1-3 h to obtain pre-treated coal with a high oxygen content; then mix it with an excess carbonate (one or more of Na2CO3, K2CO3, etc.) according to the mass ratio of salt to coal (1:1-5:1), and activate it at 700-900 °C for 1-3 h; after cooling to room temperature, wash and deash with acid to obtain the target activated carbon.

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0025] Example 1 (1) Pretreat the Zhundong coal, wash it with 1 mol / L hydrochloric acid, stir at 50 °C for 2 hours, then wash it with deionized water until neutral, and place it in a drying oven to dry at 50 °C.

[0026] (2) Take the pre-treated coal sample and pre-oxidize it at 300 °C in an air atmosphere for 3 h. Place the pre-oxidized coal sample and K2CO3 in a beaker at a mass ratio of 1:4, dissolve it with deionized water, stir at 60 °C for 2 h for mixing, and then dry it in a drying oven.

[0027] (3) Place the dried mixed sample in a tubular furnace, activate it at 800 °C in a nitrogen atmosphere for 2 h, and then naturally cool it to room temperature.

[0028] (4) The obtained material is sent into a pickling chamber for pickling and deashing, cleaned with 1 mol / L hydrochloric acid, stirred at 50 °C for 2 hours, washed with deionized water until neutral, placed in a drying oven and dried at 105 °C to obtain a porous carbon material with a large interlayer spacing and a high specific surface area.

[0029] Material analysis and characterization: Table 1 shows the specific surface area of the carbon material in Example 1

[0030] Figure 1 Specific surface area and pore structure distribution diagram of the prepared material, where (a) nitrogen adsorption-desorption isotherm, (b) pore size distribution diagram; From Figure 1 a and Table 1, it can be seen that this carbon material contains a large number of micropores and mesopore structures; from Figure 1 b, it can be seen that the pore size of this material is mainly distributed between 0.4 and 4 nm, which is beneficial to the adsorption and storage of charged ions and the adsorption of polluting gases (NO x , SO x , CO2, etc.).

[0031] Such as Figure 2 is the high-resolution transmission electron microscope image of the material. The corresponding SAED pattern and interlayer spacing are shown in the inset and at the bottom. From Figure 2 it can be seen that the sample shows a short-range disordered distribution characteristic, indicating a low degree of graphitization. The interlayer spacing of the sample can reach 0.391 nm, which is much higher than 0.335 nm of graphite, and the interlayer spacing has been greatly improved.

[0032] The present invention can increase the interlayer spacing of coal-based porous carbon and obtain a uniformly distributed pore structure through simple pre-oxidation activation; the present invention realizes the generation of a large number of pore structures through activation with a weakly corrosive carbonate.

[0033] Example 2 (1) Pretreat the Zhundong coal, clean it with 1 mol / L hydrochloric acid, stir at 50 °C for 2 hours, wash with deionized water until neutral, and place it in a drying oven and dry at 50 °C.

[0034] (2) Take the pretreated coal sample and perform pre-oxidation treatment at 300 °C for 3 h in an air atmosphere. After mixing the pre-oxidized coal sample with Na2CO3 and K2CO3, place them in a beaker at a mass ratio of 1:4 (where the mass ratio of Na2CO3 and K2CO3 is 2:2), add deionized water to dissolve, stir at 60 °C for 2 h for mixing, and then dry in a drying oven.

[0035] (3) Place the dried mixed sample in a tubular furnace, and under a nitrogen atmosphere, activate it at a temperature of 800 °C for 2 h and then naturally cool it to room temperature.

[0036] (4) Put the obtained material into the pickling chamber for pickling and ash removal, wash it with 1 mol / L hydrochloric acid, stir at 50 °C for 2 h, then wash it with deionized water until neutral, and place it in a drying oven to dry at 105 °C to obtain a porous carbon material with a large layer spacing and a high specific surface area.

[0037] Example 3 (1) Pretreat the Zhundong coal, wash it with 1 mol / L hydrochloric acid, stir at 50 °C for 2 h, then wash it with deionized water until neutral, and place it in a drying oven to dry at 50 °C.

[0038] (2) Take the pretreated coal sample and pre-oxidize it at a temperature of 300 °C for 3 h in an air atmosphere. Place the pre-oxidized coal sample and Na2CO3 in a beaker at a mass ratio of 1:4, add deionized water to dissolve it, and stir at 60 °C for 2 h for mixing, and then dry it in a drying oven.

[0039] (3) Place the dried mixed sample in a tubular furnace, and under a nitrogen atmosphere, activate it at a temperature of 800 °C for 2 h and then naturally cool it to room temperature.

[0040] (4) Put the obtained material into the pickling chamber for pickling and ash removal, wash it with 1 mol / L hydrochloric acid, stir at 50 °C for 2 h, then wash it with deionized water until neutral, and place it in a drying oven to dry at 105 °C to obtain a porous carbon material with a large layer spacing and a high specific surface area.

[0041] Example 4 (1) Pretreat the Zhundong coal, wash it with 3 mol / L hydrochloric acid, stir at 45 °C for 3 h, then wash it with deionized water until neutral, and place it in a drying oven to dry at 60 °C.

[0042] (2) Take the pretreated coal sample and pre-oxidize it at a temperature of 200 °C for 3 h in an oxygen atmosphere. Place the pre-oxidized coal sample and Na2CO3 in a beaker at a mass ratio of 1:1, add deionized water to dissolve it, and stir at 60 °C for 2 h for mixing, and then dry it in a drying oven.

[0043] (3) Place the dried mixed sample in a tubular furnace, and under a nitrogen atmosphere, activate it at a temperature of 700 °C for 3 h and then naturally cool it to room temperature.

[0044] (4) The obtained material is sent to the pickling chamber for pickling and deashing, washed with 2 mol / L hydrochloric acid, stirred at 50 °C for 2 hours, then washed with deionized water until neutral, and placed in a drying oven to dry at 90 °C to obtain a porous carbon material with a large interlayer spacing and a high specific surface area.

[0045] Example 5 (1) Pretreat the Zhundong coal, wash it with 1 mol / L hydrochloric acid, stir at 60 °C for 1 hour, then wash with deionized water until neutral, and place in a drying oven to dry at 70 °C.

[0046] (2) Take the pretreated coal sample and perform pre-oxidation treatment at 350 °C for 1 h in an air atmosphere. Place the pre-oxidized coal sample and Na2CO3 in a beaker at a mass ratio of 1:2, add deionized water to dissolve, and stir at 60 °C for 2 h for mixing, and then dry in a drying oven.

[0047] (3) Place the dried mixed sample in a tubular furnace, activate it at 900 °C for 3 h in a nitrogen atmosphere, and then naturally cool to room temperature.

[0048] (4) The obtained material is sent to the pickling chamber for pickling and deashing, washed with 3 mol / L hydrochloric acid, stirred at 50 °C for 2 hours, then washed with deionized water until neutral, and placed in a drying oven to dry at 120 °C to obtain a porous carbon material with a large interlayer spacing and a high specific surface area.

[0049] Example 6 (1) Pretreat the Zhundong coal, wash it with 2 mol / L hydrochloric acid, stir at 60 °C for 1 hour, then wash with deionized water until neutral, and place in a drying oven to dry at 70 °C.

[0050] (2) Take the pretreated coal sample and perform pre-oxidation treatment at 350 °C for 1 h in an oxygen atmosphere. Place the pre-oxidized coal sample and K2CO3 in a beaker at a mass ratio of 1:3, add deionized water to dissolve, and stir at 60 °C for 2 h for mixing, and then dry in a drying oven.

[0051] (3) Place the dried mixed sample in a tubular furnace, activate it at 850 °C for 3 h in an argon atmosphere, and then naturally cool to room temperature.

[0052] (4) The obtained material is sent to the pickling chamber for pickling and deashing, washed with 2 mol / L hydrochloric acid, stirred at 50 °C for 2 hours, then washed with deionized water until neutral, and placed in a drying oven to dry at 90 °C to obtain a porous carbon material with a large interlayer spacing and a high specific surface area.

[0053] Example 7 (1) Pretreat the Zhundong coal, wash it with 2 mol / L hydrochloric acid, stir at 60 °C for 1 hour, then wash it with deionized water until neutral, and place it in a drying oven to dry at 70 °C.

[0054] (2) Take the pretreated coal sample and perform pre-oxidation treatment at 350 °C for 1 h in an oxygen and air atmosphere (where the volume ratio of oxygen to air is 1:1). Place the pre-oxidized coal sample and K2CO3 in a beaker at a mass ratio of 1:5, add deionized water to dissolve it, stir at 60 °C for 2 h for mixing, and then dry it in a drying oven.

[0055] (3) Place the dried mixed sample in a tubular furnace, perform activation treatment at 850 °C for 2 h in an argon atmosphere, and then naturally cool to room temperature.

[0056] (4) Put the obtained material into an acid washing chamber for acid washing and ash removal, wash it with 2 mol / L hydrochloric acid, stir at 50 °C for 2 hours, then wash it with deionized water until neutral, and place it in a drying oven to dry at 90 °C to obtain a porous carbon material with a large layer spacing and a high specific surface area.

[0057] In the present invention, if there is no special instruction, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0058] In the present invention, if there is no special instruction, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0059] In the present invention, if there is no special instruction, the percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0060] In the present invention, if there is no special instruction, the various components or their preferred components involved can be combined with each other to form a new technical solution.

[0061] In the present invention, unless otherwise specified, the numerical range "a~b" represents the abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been fully listed herein, and "6~22" is only the abbreviated representation of these numerical combinations.

[0062] The "range" disclosed in the present invention can be in the form of one or more lower limits and one or more upper limits, respectively.

[0063] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0064] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in order. Preferably, the reaction methods herein are carried out sequentially.

[0065] Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to persons skilled in the art. In addition, any methods or materials similar to or equivalent to the described content can also be applied to the present invention.

[0066] It should be noted that the terms "comprising" and "having" and any variations thereof in the description and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0067] It should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the technical field to which the present invention pertains. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0069] As mentioned above, it is only a preferred embodiment of the present invention and does not impose any formal limitations on the present invention; any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings of the specification and described above; however, any minor changes, modifications and evolutions made by those skilled in the art within the scope of the technical solution of the present invention by using the technical content disclosed above are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment, characterized in that, including After the pretreated coal sample is subjected to low-temperature pre-oxidation treatment in an oxidizing atmosphere, the pre-oxidized coal sample is mixed with carbonate, and then the mixed sample is subjected to high-temperature activation treatment in an inert atmosphere to obtain a high-interlayer-spacing porous carbon material based on coal pre-oxidation treatment.

2. The preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, characterized in that, The pretreatment process of coal is as follows: The coal is washed with 1-3 mol / L hydrochloric acid, stirred at 45-60 °C for 1-3 h, washed with deionized water until neutral, and dried for later use.

3. The preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, characterized in that, The oxidizing atmosphere is at least one of oxygen and air.

4. The preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, wherein, The specific process of the low-temperature pre-oxidation treatment is as follows: The pretreated coal sample is heated to 200-350 °C in an oxidizing atmosphere, kept warm for 1-3 h, and then cooled to room temperature to obtain a pre-oxidized coal sample.

5. The preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, characterized in that, The carbonate is at least one of Na2CO3 and K2CO3.

6. A method for preparing a high-interlayer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, wherein the mass ratio of the pretreated coal sample to the carbonate is 1:1 to 1:

5.

7. A method for preparing a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, characterized in that, The specific process of the high-temperature activation treatment is as follows: The mixed sample of the pre-oxidized coal sample and the carbonate is heated to 700-900 °C in an inert atmosphere, kept warm for 1-3 h, and then cooled to room temperature in an inert atmosphere to obtain a high-interlayer-spacing porous carbon material based on coal pre-oxidation treatment.

8. The preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, characterized in that, The inert atmosphere uses nitrogen or argon.

9. The preparation method of a high-layer-spacing porous carbon material based on coal pre-oxidation treatment according to claim 1, characterized in that, The sample after high-temperature activation treatment is subjected to acid washing and ash removal, washed with water until neutral, and dried at 90-120 °C to obtain a high-interlayer-spacing porous carbon material based on coal pre-oxidation treatment.

10. A high-interlayer-spacing porous carbon material based on coal pre-oxidation treatment, prepared by the method for preparing a high-interlayer-spacing porous carbon material based on coal pre-oxidation treatment according to any one of claims 1-9.

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