Acid and alkali synergistic deliming method of porous carbon material, porous carbon material and application

Abstract

The invention relates to the technical field of porous carbon material preparation, in particular to an acid and alkali synergistic deliming method of a porous carbon material, the porous carbon material and application, porous carbon is soaked in an aqueous solution, alkali is added to enable the concentration of OH <-> in the aqueous solution soaked with the porous carbon to be 1-10 mol / L, preliminary deliming mixed slurry is heated and filtered to obtain pre-deliming porous carbon, and the pre-deliming porous carbon is subjected to acid and alkali synergistic deliming. The combination of ash and a carbon matrix of the porous carbon material is destroyed by using a strong alkaline environment, residual ash in pores is released, and 60-80% of ash in porous carbon is removed; the method comprises the following steps: pre-deliming porous carbon, placing the pre-delimed porous carbon in an acidic solution for a hydrothermal reaction to obtain deeply delimed porous carbon, completing acid-alkali synergistic deliming of the porous carbon material, further deeply dissolving alkaline ash by adopting secondary deliming of the acidic solution to realize deep removal of ash, and ensuring that the ash content in the delimed porous carbon material is 1t; the method is more suitable for the field with strict purity requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of porous carbon materials, and specifically to an acid-base synergistic ash removal method for porous carbon materials, porous carbon materials and applications thereof. Background Art

[0002] Porous carbon is a carbon material with a developed pore structure. There are a large number of interconnected or closed pores inside it. These pores endow porous carbon with unique physical and chemical properties, mainly including activated carbon, carbon molecular sieve, mesoporous carbon, activated carbon fiber and nanoporous carbon. Most porous carbons have a large specific surface area, good physical and chemical stability and a wide pore size distribution range. According to the pore size, it can be divided into micropores (pore size less than 2 nm), mesopores (pore size 2-50 nm) and macropores (pore size greater than 50 nm). Combining the advantages that the raw materials of porous carbon materials are rich and easy to obtain, and can be combined with different atoms through different hybridization methods, thus having many advantages such as electrical conductivity, thermal conductivity and stable chemical properties, making it show broad application prospects in many fields, especially in the fields of adsorption, catalysis and energy storage, it has good utilization value.

[0003] The precursors of porous carbon materials may contain a large amount of ash. During the process of preparing carbon materials, these ash will also be brought into the materials, reducing the performance of porous carbon materials in various fields. The porous carbon materials can be subjected to ash removal treatment to achieve higher use value.

[0004] At present, there are mainly three mainstream deashing methods, namely physical deashing, chemical deashing, and physical-chemical deashing. Among them, physical deashing mainly relies on the differences in physical properties of different components (such as coal and ash) in the porous carbon material precursor, and realizes separation through the action of an external physical field. There are mainly magnetic separation, electrostatic separation, and flotation methods, etc. Magnetic separation uses the magnetic differences of certain minerals (such as ferromagnetic minerals) in the ash to separate them from the raw material through the action of a magnetic field; electrostatic separation is based on the electrical differences of mineral particles, and different components are separated due to different forces in a high-voltage electric field; flotation method is to adjust the pH value of the pulp, add collectors and frothers, so that the target minerals adhere to the bubbles and float, while the ash remains in the pulp. Although the methods in the above physical deashing process are simple to operate and have low costs, the separation and ash removal efficiency are low, and it is difficult to meet the requirements of high purity and production efficiency. Chemical deashing mainly reacts acidic or alkaline reagents with relevant inorganic minerals and organic components in coal to achieve the purpose of removing coal ash, mainly including acid washing or alkali washing methods. Its deashing efficiency is very high, but the deashing purity is low and cannot meet the requirements of high-end applications such as supercapacitors. The physical-chemical method combines physical and chemical deashing methods and has good effects in deashing and demineralization, but there are too many limiting conditions for industrial implementation, and most of them are still in the laboratory stage. Therefore, there is an urgent need for a method that can achieve high-purity deashing to meet the requirement that the ash content of activated carbon for supercapacitors is less than 0.2%, and to promote the development of supercapacitors. Summary of the Invention

[0005] Aiming at the problem of incomplete deashing of porous carbon materials in the prior art, the present invention provides an acid-base synergistic deashing method, a porous carbon material and an application thereof for porous carbon materials.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides an acid-base synergistic deashing method for porous carbon materials, including: Immerse the porous carbon in an aqueous solution and add an alkali to make the OH – concentration in the aqueous solution immersed with the porous carbon be 1-10 mol / L to obtain a preliminary deashing mixed slurry; Heat and filter the preliminary deashing mixed slurry to obtain pre-deashed porous carbon; Place the pre-deashed porous carbon in an acidic solution for hydrothermal reaction to obtain deeply deashed porous carbon, and complete the acid-base synergistic deashing of the porous carbon material.

[0007] Optionally, the porous carbon is a chemically activated porous carbon.

[0008] Optionally, the H + concentration of the acidic solution is 1-5 mol / L.

[0009] Optionally, the base is NaOH and / or KOH.

[0010] Optionally, the acidic solution is a hydrofluoric acid solution or a hydrochloric acid solution.

[0011] Optionally, the ratio of the pre - deashed porous carbon to the acidic solution is: 1 g:(10 - 100) mL.

[0012] Optionally, the porous carbon is immersed in an aqueous solution, and a base is added to make the concentration of OH in the aqueous solution containing the porous carbon – be 1 - 10 mol / L, and the reaction conditions for obtaining the preliminarily deashed mixed slurry are 60°C - 90°C, and the reaction time is 2 - 12 h.

[0013] Optionally, the reaction conditions for subjecting the pre - deashed porous carbon to hydrothermal reaction in an acidic solution to obtain the deeply deashed porous carbon are 150°C - 300°C.

[0014] A porous carbon material is deashed by using the above - mentioned acid - base synergistic deashing method.

[0015] The application of the porous carbon material as described above in a supercapacitor.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an acid - base synergistic deashing method for a porous carbon material. The method immerses the porous carbon in an aqueous solution and adds a base to make the concentration of OH in the aqueous solution containing the porous carbon – be 1 - 10 mol / L, heats and filters the preliminarily deashed mixed slurry to obtain the pre - deashed porous carbon; the preliminary deashing with the base can make full use of the residual alkali activator in the porous carbon, which can not only reduce the use of the base and lower the deashing cost, but also make the OH in the preliminarily deashed mixed slurry –Preferentially dissolve acidic ash (such as SiO2 or silicate, etc.), and at the same time use a strong alkaline environment to break the bond between the ash and the carbon matrix of the porous carbon material, release the residual ash in the pores, and remove 60% - 80% of the ash in the porous carbon; then place the pre - deashed porous carbon in an acidic solution for hydrothermal reaction to obtain deeply deashed porous carbon, completing the acid - base synergistic deashing of the porous carbon material. The secondary deashing with an acidic solution can further deeply dissolve alkaline ash (such as Fe2O3, Al2O3 or metal oxides, etc.). Hydrothermal conditions can greatly reduce the viscosity of water and significantly improve the migration characteristics of water molecules and solute molecules; at the same time, the ionic product of water molecules will also be greatly increased, which can effectively promote the dissolution and precipitation of ash inside the particles, realizing deep removal of ash. Compared with the traditional single - component ash removal, it not only deashes more thoroughly, but also overcomes the limitations of traditional single - acid pickling or alkali washing. The entire deashing process can achieve high - efficiency deashing without high - pressure equipment, with low energy consumption cost, and the alkaline pretreatment waste liquid (containing excessive OH - )and the acidic hydrothermal waste liquid (containing H + )can be directly mixed and neutralized, reducing the consumption of acids and alkalis. The pH value of the waste liquid after neutralization is close to neutral, which can greatly reduce the subsequent treatment difficulty and cost. The staged treatment avoids the damage to the framework of the porous carbon material caused by long - time soaking in a single strong acid / alkali. While deashing, it maintains the high specific surface area and porosity of the material. This method is simple, and the ash content in the deashed porous carbon material is <0.2%, which is more suitable for fields with strict purity requirements (such as supercapacitor electrode materials, catalyst carriers), reducing side reactions or performance attenuation caused by ash, and having advantages in terms of good process economy, environmental friendliness and material performance protection, providing an efficient and low - cost solution for the industrial production of high - performance porous carbon materials.

[0017] The porous carbon is the porous carbon after chemical activation. Usually, unreacted alkali activators remain in the porous carbon after chemical activation. In the alkaline pretreatment stage of the present invention, these residual alkalis are directly used to form an OH - solution with a concentration of 1 - 10 mol / L, reducing the addition amount of externally added strong alkali, significantly reducing the raw material cost. And in the traditional process, it is necessary to additionally wash to remove the residual alkali, while the present invention incorporates the residual alkali into the deashing process, not only avoiding the environmental risk of direct discharge of waste alkali liquid, but also realizing resource utilization.

[0018] The H + concentration of the acidic solution is 1 - 5 mol / L. When the H + concentration > 5 mol / L, the strong acidic environment is likely to cause oxidation of the porous carbon material, damage the pore structure, and reduce the specific surface area; while the H + concentration of 1 - 5 mol / L can, while ensuring the deashing efficiency, keep the specific surface area retention rate of the deashed porous carbon material > 98%, and the micropore and mesopore structures are complete, which is suitable for high - precision adsorption or electrode material applications.

[0019] The base is NaOH and / or KOH. Selecting NaOH and / or KOH as the base source in the alkaline pretreatment stage is highly compatible with the chemical activation process of the porous carbon material, the ash removal requirement, and the industrial production conditions. When preparing porous carbon by the chemical activation method, NaOH or KOH is usually used as the activator, and the unreacted NaOH / KOH remaining in the porous carbon is used as the base source, reducing the addition amount of externally added strong base and realizing the recycling of resources.

[0020] The acidic solution is a hydrofluoric acid solution or a hydrochloric acid solution. HF can react quickly with ash such as SiO2 and silicates, and has a relatively high removal rate for silicon-based ash, significantly superior to other inorganic acids. Moreover, HF has a small molecular weight and low viscosity, and is more likely to diffuse into the micropores of the porous carbon under high-temperature hydrothermal conditions to dissolve deep silicon-based impurities; HCl has a high dissolution efficiency for metal oxide ash such as Fe2O3, Al2O3, and CaO, and after the HCl waste liquid is neutralized with the alkali-washing waste liquid, it can be directly subjected to biochemical treatment or evaporation crystallization to recover salts, with low treatment costs.

[0021] The ratio of the pre-ashed porous carbon to the acidic solution is: 1 g : (10 - 100) mL. The liquid-solid ratio of 10 - 100 mL / g ensures that the porous carbon material is completely immersed in the acidic solution, and the acidic solution fully penetrates into the micropores and mesopores, effectively increasing the contact area of the ash, especially having a significant effect on removing deeply wrapped ash (such as silicate-metal oxide composite particles).

[0022] The step of immersing the porous carbon in an aqueous solution and adding a base to make the OH – concentration in the aqueous solution containing the porous carbon be 1 - 10 mol / L, and the reaction conditions for obtaining the preliminarily deashed mixed slurry be 60°C - 90°C and the reaction time be 2 - 12 h. Under the conditions of 60°C - 90°C, the reaction kinetics can be improved, and the dissolution rate of the ash can be increased by 3 - 5 times compared with room temperature (25°C). While balancing the reaction sufficiency and energy consumption cost, the temperature range of 60°C - 90°C can avoid excessive oxidation of the carbon skeleton by strong bases (such as NaOH), without the need for high-temperature and high-pressure equipment, and the energy consumption cost per ton of treatment is reduced by more than 60% compared with the traditional high-temperature alkali fusion method.

[0023] The reaction conditions for subjecting the pre-ashed porous carbon to hydrothermal reaction in the acidic solution to obtain the deeply deashed porous carbon are 150°C - 300°C. The high temperature (150°C - 300°C) significantly increases the activity and reaction rate of H + in the acid solution, promotes the reaction between the silicate and the acid solution, reduces the residue of the silicon-based ash; at the same time, promotes the diffusion of the acidic solution inside the porous carbon material to further improve the ash removal rate.

[0024] A porous carbon material is deashed by using the above-mentioned acid-base synergistic deashing method. Since the acid-base synergistic deashing scheme is adopted, the total ash content of this porous carbon material is less than 0.2%, and it has a complete skeleton and better electrical conductivity. When used in supercapacitors or battery electrodes, the specific capacitance and cycle stability are significantly improved. The preparation method is simple, the cost is low, and the application scenarios are more extensive.

[0025] As described above, the application of the porous carbon material in supercapacitors. The porous carbon material after acid-base synergistic deashing has a high specific surface area and a complete skeleton structure, which can provide more active sites for charge adsorption, enhance the Electric Double Layer Capacitor (EDLC) effect. The unique mesoporous structure of the porous carbon material can provide channels for ion transport, reduce the diffusion resistance, and has good stability and is not easy to collapse, making the prepared supercapacitor have higher specific capacitance, power density and cycle life, which promotes the development of supercapacitors. Brief Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the acid-base synergistic deashing method of a porous carbon material of the present invention.

[0027] Figure 2 It is a comparison chart of the acid-base synergistic deashing of the porous carbon material in Example 1 of the present invention and the deashing effects of Comparative Examples 1-4; among them, a is the comparison chart of the total ash content, b is the comparison chart of the ash content of Fe element, c is the comparison chart of the ash content of Ca element, and d is the comparison chart of the ash content of Si element. Detailed Embodiments

[0028] To enable those skilled in the art to understand the features and effects of the present invention, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. When there is a conflict, the definition in this specification shall prevail.

[0029] The theories or mechanisms described and disclosed herein, whether correct or not, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0030] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0031] In this text, unless otherwise specified, the terms "comprise", "include", "contain", "have" or similar terms cover the meanings of "consist of" and "consist essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0032] In this text, for the sake of brevity of description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered to be within the scope described in this specification.

[0033] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0034] Conventional instruments and equipment in the art are used in the following examples. For the experimental methods without specific conditions indicated in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturers. Various raw materials are used in the following examples. Unless otherwise stated, commercially available products are used, and their specifications are the conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0035] The present invention will be further described in detail below in conjunction with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0036] The precursors of existing porous carbon materials (such as coal, organic solid waste, biomass, etc.) contain a large amount of ash. During the carbonization and activation processes of the precursors, the proportion of ash precipitated with the gas is relatively low, and a large amount of ash accumulates in the target carbon material. The residual ash in the porous carbon material will have a greater impact on the cycle stability of supercapacitors using the porous carbon material as an electrode, resulting in a reduction in the cycle life. The existing conventional ash removal methods cannot achieve deep ash removal, resulting in limited application of porous carbon materials in supercapacitors. Therefore, referring to Figure 1 , the present invention discloses an acid-base synergistic ash removal method for porous carbon materials, comprising: S1: Immerse the porous carbon in an aqueous solution and add an alkali to make the concentration of OH – in the aqueous solution immersed with the porous carbon be 1-10 mol / L to obtain a preliminary ash removal mixed slurry, specifically: Place the porous carbon in water, add an alkali, and make the concentration of OH –With a concentration of 1 - 10 mol / L, a preliminary deashing mixed solution is obtained; the alkali used is NaOH and / or KOH, preferably NaOH.

[0037] S2: Heat and filter the preliminary deashing mixed slurry to obtain pre - deashed porous carbon, specifically: After the preliminary deashing mixed solution is reacted at 60°C - 90°C with continuous stirring for 2 - 12 h, it is simply washed with water to remove the residual alkali solution on the porous carbon, and pre - deashed porous carbon is obtained; in this process, the porous carbon is preferably chemically activated porous carbon. By reasonably matching the residual alkali activator in the porous carbon material with water and alkali, 60% - 80% of the ash in the porous carbon material is removed, and the alkali dosage is small, with low cost.

[0038] S3: Place the pre - deashed porous carbon in an acidic solution for hydrothermal reaction to obtain deeply deashed porous carbon, completing the acid - alkali synergistic deashing of the porous carbon material, specifically: Place the pre - deashed porous carbon in an + acidic solution with a concentration of 1 - 5 mol / L. Under the conditions of 150°C - 300°C, react for 2 - 3 h. After cooling to room temperature, filter, and wash the filter residue repeatedly with deionized water until neutral to obtain deeply deashed porous carbon, completing the acid - alkali synergistic deashing of the porous carbon material. In this process, under hydrothermal conditions, the viscosity of water is greatly reduced, and the migration characteristics of water molecules and solute molecules are greatly improved; at the same time, the ionic product of water molecules will also increase significantly, which can promote the dissolution and precipitation of ash inside the particles, realizing the deep removal of ash. At the same time, the hydrothermal process of the acidic solution can also deeply remove the added metal substances (such as K, Na, etc.) during the activation and alkali washing processes. Preferably, the acidic solution is a hydrofluoric acid solution or a hydrochloric acid solution, and further preferably a hydrochloric acid solution; the ratio of pre - deashed porous carbon to the acidic solution is: 1 g:(10 - 100) mL.

[0039] After the acid - alkali solution synergistic deep deashing of the porous carbon material, more than 99.8% of the ash is removed; the opening of the voids left after deashing and the pores blocked by ash can slightly increase the specific surface area of the material; at the same time, it will also improve the distribution of functional groups on the material surface, enhancing. And the deashing reagent can not only remove ash, but also promote the change of functional groups on the surface of the porous carbon material, improving the use performance of the porous carbon material.

[0040] A porous carbon material is deashed by using the above - mentioned acid - alkali synergistic deashing method. Since the acid - alkali synergistic deashing scheme is adopted, the total ash content of this porous carbon material is less than 0.2%, it has a complete skeleton and better electrical conductivity. When used as a supercapacitor or battery electrode, the specific capacitance and cycle stability are significantly improved. The preparation method is simple, the cost is low, and the application scenario is wider.

[0041] The application of the porous carbon material as described above in supercapacitors. After acid-alkali synergistic deashing, the porous carbon material has a high specific surface area and a complete skeleton structure, which can provide more active sites for charge adsorption, enhance the electric double layer capacitance effect. The unique mesoporous structure of the porous carbon material can provide channels for ion transport, reduce the diffusion resistance, and has good stability and is not easy to collapse, making the prepared supercapacitor have a higher specific capacitance, power density and cycle life, which promotes the development of supercapacitors.

[0042] Example 1 The porous carbon material (denoted as AC) with an ash content (mass percentage) of 4.33% after chemical activation was impregnated in water, and NaOH was added to make the OH – concentration reach 6 mol / L to obtain a preliminary deashing mixed slurry; the preliminary deashing mixed slurry was heated to 60 °C and continuously stirred, filtered after maintaining for 6 h, and a large amount of residual alkaline solution on the solid was removed by simple water washing to obtain pre-deashed porous carbon.

[0043] The pre-deashed porous carbon was mixed with 2 mol / L hydrochloric acid solution in a ratio of 1 g:30 mL, placed in a hydrothermal reaction kettle, heated to 200 °C for deep deashing, filtered after cooling to room temperature; the filter residue was repeatedly washed with deionized water until neutral and dried to obtain deeply deashed porous carbon denoted as AC-NaOH-HCl, completing the acid-alkali synergistic deashing of the porous carbon material.

[0044] Finally, the acid and alkali washing waste liquids were neutralized to reduce the treatment difficulty of the subsequent waste liquids.

[0045] Example 2 The porous carbon material after chemical activation was impregnated in water, and KOH was added to make the OH – concentration reach 1 mol / L to obtain a preliminary deashing mixed slurry; the preliminary deashing mixed slurry was heated to 90 °C and continuously stirred, filtered after maintaining for 12 h, and a large amount of residual alkaline solution on the solid was removed by simple water washing to obtain pre-deashed porous carbon.

[0046] The pre-deashed porous carbon was mixed with 1 mol / L hydrochloric acid solution in a ratio of 1 g:20 mL, placed in a hydrothermal reaction kettle, heated to 150 °C for deep deashing, filtered after cooling to room temperature; the filter residue was repeatedly washed with deionized water until neutral and dried to obtain deeply deashed porous carbon, completing the acid-alkali synergistic deashing of the porous carbon material.

[0047] Example 3 The porous carbon material after chemical activation was impregnated in water, and KOH was added to make the OH –The concentration reaches 8 mol / L to obtain a preliminary deashing mixed slurry; the preliminary deashing mixed slurry is heated to 70 °C and continuously stirred. After maintaining for 10 h, it is filtered, and a large amount of residual alkaline solution on the solid is removed by simple water washing to obtain pre-deashed porous carbon.

[0048] The pre-deashed porous carbon is mixed with a 3 mol / L hydrofluoric acid solution in a ratio of 1 g:60 mL, placed in a hydrothermal reaction kettle, heated to 180 °C for deep deashing, and filtered after cooling to room temperature; the filter residue is repeatedly washed with deionized water until neutral and then dried to obtain deeply deashed porous carbon, completing the acid-base synergistic deashing of the porous carbon material.

[0049] Example 4 The chemically activated porous carbon material is impregnated in water, and NaOH is added to make the OH – The concentration reaches 10 mol / L to obtain a preliminary deashing mixed slurry; the preliminary deashing mixed slurry is heated to 60 °C and continuously stirred. After maintaining for 2 h, it is filtered, and a large amount of residual alkaline solution on the solid is removed by simple water washing to obtain pre-deashed porous carbon.

[0050] The pre-deashed porous carbon is mixed with a 5 mol / L hydrofluoric acid solution in a ratio of 1 g:100 mL, placed in a hydrothermal reaction kettle, heated to 170 °C for deep deashing, and filtered after cooling to room temperature; the filter residue is repeatedly washed with deionized water until neutral and then dried to obtain deeply deashed porous carbon, completing the acid-base synergistic deashing of the porous carbon material.

[0051] Comparative Example 1 The chemically activated porous carbon material with an ash content (mass percentage) of 4.33% (denoted as AC) is impregnated in water, and NaOH is added to make the OH – The concentration reaches 6 mol / L to obtain a preliminary deashing mixed slurry; the preliminary deashing mixed slurry is heated to 60 °C and continuously stirred. After maintaining for 6 h, it is filtered, and a large amount of residual alkaline solution on the solid is removed by simple water washing to obtain deashed porous carbon, denoted as AC-NaOH.

[0052] Comparative Example 2 The chemically activated porous carbon material with an ash content (mass percentage) of 4.33% (denoted as AC) is impregnated in water, and KOH is added to make the OH – The concentration reaches 6 mol / L to obtain a preliminary deashing mixed slurry; the preliminary deashing mixed slurry is heated to 60 °C and continuously stirred. After maintaining for 6 h, it is filtered, and a large amount of residual alkaline solution on the solid is removed by simple water washing to obtain deashed porous carbon, denoted as AC-KOH.

[0053] Comparative Example 3 The porous carbon material with an ash content of 4.33% (by mass percentage) after chemical activation (denoted as AC) was mixed with a 2 mol / L hydrochloric acid solution at a ratio of 1 g:30 mL, placed in a hydrothermal reactor, heated to 200 °C for deep deashing, filtered after cooling to room temperature; the filter residue was repeatedly washed with deionized water until neutral, dried, and the deashed porous carbon was denoted as AC-HCl.

[0054] Comparative Example 4 The porous carbon material with an ash content of 4.33% (by mass percentage) after chemical activation (denoted as AC) was mixed with a 2 mol / L hydrofluoric acid solution at a ratio of 1 g:30 mL, placed in a hydrothermal reactor, heated to 200 °C for deep deashing, filtered after cooling to room temperature; the filter residue was repeatedly washed with deionized water until neutral, dried, and the deashed porous carbon was denoted as AC-HF.

[0055] See Figure 2 After the deashed porous carbon materials in Example 1 and Comparative Examples 1-4 were tested for ash content and ash content of different elements, it was found that the total ash content after acid-base synergistic deashing provided by the present invention was 0.19%, which was lower than that of other single-component deashing methods. From the perspective of the deashing of individual elements, HCl washing was beneficial to the removal of Fe, Ca, etc., while alkali washing and HF washing were beneficial to the removal of Si, but there were certain limitations for the removal of total ash.

[0056] In summary, the present invention provides an acid-base synergistic deashing method, a porous carbon material and its application for a porous carbon material. The present invention adopts a sequential deashing method with stepped acid and alkali solutions, and fully utilizes the residual alkali activator in the porous carbon to form an alkali solution to achieve preliminary deashing of 60% - 80% of the ash at normal pressure and low temperature; then, by utilizing the characteristics of reduced viscosity of water and increased ionic product at high pressure and medium temperature, acidic deep deashing of the ash at high pressure and medium temperature is realized. This stepped deashing method can not only reduce the usage amount of acid solution in the high-pressure medium-temperature hydrothermal process to achieve the purpose of energy saving; at the same time, by utilizing the difference in the solubility of acid and alkali solutions in ash, deep deashing of more types of ash is realized. In addition, the acid and alkali washing waste liquid can be neutralized to reduce the difficulty of subsequent waste liquid treatment.

[0057] The above are only the preferred embodiments of the present invention, and are not used to limit the technical solutions of the present invention in any way. Those skilled in the art should understand that without departing from the spirit and principles of the present invention, the technical solutions can be modified and replaced in several simple ways, and these modifications and replacements also fall within the protection scope covered by the claims.

Claims

1. A method for synergistic acid and alkali deashing of a porous carbon material, characterized in that Comprising: Immerse the porous carbon in an aqueous solution and add an alkali so that the OH – concentration in the aqueous solution immersed with the porous carbon is 1 to 10 mol / L to obtain a preliminary deashing mixed slurry; Heating and filtering the preliminary deashing mixed slurry to obtain pre-deashed porous carbon; Placing the pre-deashed porous carbon in an acidic solution for hydrothermal reaction to obtain deeply deashed porous carbon, completing the acid and alkali co-deashing of the porous carbon material.

2. The acid-base synergistic ash removal method of the porous carbon material according to claim 1, wherein, The porous carbon is the porous carbon after chemical activation.

3. The acid and base synergistic deashing method of the porous carbon material according to claim 1, wherein The H of the acidic solution + has a concentration of 1 to 5 mol / L.

4. The acid and base synergistic deashing method of the porous carbon material according to claim 1, wherein, The alkali is NaOH and / or KOH.

5. The acid and base synergistic deashing method of the porous carbon material according to claim 1, characterized in that, The acidic solution is a hydrofluoric acid solution or a hydrochloric acid solution.

6. The acid and base synergistic deashing method of the porous carbon material according to claim 1, wherein, The ratio of the pre-deashed porous carbon to the acidic solution is: 1 g:(10 - 100) mL.

7. The acid-base synergistic deashing method of the porous carbon material according to claim 1, wherein, The porous carbon is immersed in an aqueous solution, and an alkali is added so that the OH – concentration in the aqueous solution immersed with the porous carbon is 1 to 10 mol / L, and the reaction conditions for obtaining the preliminary deashing mixed slurry are 60°C to 90°C, and the reaction time is 2 to 12 h.

8. The acid-base synergistic deashing method of the porous carbon material according to claim 1, characterized in that, The reaction conditions for placing the pre-deashed porous carbon in the acidic solution for hydrothermal reaction to obtain deeply deashed porous carbon are 150°C - 300°C.

9. A porous carbon material, characterized in that, Using the acid and alkali co-deashing method according to any one of claims 1 - 8 for deashing.

10. Application of the porous carbon material according to claim 9 in a supercapacitor.

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