Capacitive activated carbon purification method

Abstract

The application discloses a capacitive activated carbon purification method and relates to the technical field of activated carbon material preparation.The application comprises the following steps: physically removing magnetic substances from the activated sample; adding potassium hydroxide to the sample, and then performing ultrasonic treatment and mechanical heating and stirring; performing water washing after temperature reduction, and then performing dehydration; adding hydrochloric acid to the sample, and then performing ultrasonic treatment and mechanical heating and stirring; performing secondary water washing after temperature reduction, and then performing dehydration; drying; and performing quality inspection and subpackaging.The method disclosed by the application can improve the purity of activated carbon by physically removing iron, ultrasonic treatment combined with mechanical stirring, and water-heat coupling linkage cooperation, greatly shorten the production cycle, and is suitable for a wide range of applications.

Description

Technical Field

[0001] This invention relates to the field of activated carbon material preparation technology, specifically a method for purifying capacitor activated carbon. Background Technology

[0002] Supercapacitor activated carbon is a new type of porous carbon material with a large specific surface area, well-developed mesopores, and a reasonable pore structure distribution. It has broad application prospects in supercapacitors, energy storage, medical treatment, and military applications.

[0003] Currently, the main process for preparing activated carbon for supercapacitors is the alkali activation method, which involves crushing, screening, mixing with alkali, activating, and purifying raw materials such as petroleum coke, coal, and coconut shells. Because alkali is highly corrosive at high temperatures, it causes significant corrosion to equipment, introducing heavy metals into the activated material. The presence of these heavy metals makes the capacitor prone to short circuits during charging and discharging, increases its own discharge level, and increases leakage current, thus affecting its service life. Existing technologies have provided some solutions to this problem, but they have many drawbacks, which are briefly explained below.

[0004] I. Patent application “102502621 A” published “A post-processing method for preparing ultra-low ash activated carbon for supercapacitors” utilizes the high temperature and high pressure characteristics of hydrothermal technology and adopts alkaline washing, acid washing and water washing methods to reduce the ash impurity content of activated carbon, making it a suitable electrode material for supercapacitors. However, using this method, a long soaking time is required before hydrothermal treatment, and the treated material is in a static state, resulting in a relatively long production cycle.

[0005] II. Patent "200810121706.8" discloses a "washing method for activated carbon for electrodes," which uses ultrasonic and microwave (including high-frequency electromagnetic waves) radiation to promote dissolution, combined with repeated soaking and washing with hot water and hot acid, to significantly reduce the heavy metal content in activated carbon to below 200 ppm. However, this method requires pre-washing the activated carbon, making the process relatively cumbersome. Furthermore, the activated carbon used in this method is alkali-activated samples, and the carbon-containing material is phenolic resin. Capacitor activated carbon, on the other hand, involves not only alkali activation but also physical activation processes.

[0006] Third, the activated carbon refining process published in patent application "101269810A" involves processing crude activated carbon through a preparation A process, followed by processing the activated carbon through a preparation B process, and finally drying and sieving to obtain the finished activated carbon. Although the activated carbon produced by this process has a low impurity content and can be used in the pharmaceutical and food industries, it does not meet the requirements for activated carbon used in electrodes. Summary of the Invention

[0007] To address the problems of high impurity content, long production cycle, and the tendency of heavy metals to cause short circuits and affect the service life of activated carbon used in supercapacitors, this invention provides a method for purifying activated carbon for supercapacitors.

[0008] This invention employs the following technology: This invention provides a method for purifying capacitive activated carbon, comprising the following steps:

[0009] a) Physical iron removal

[0010] After activation, the sample is physically removed by using a strong magnet to remove magnetic substances such as iron and nickel. Specifically, the strong magnet is used to repeatedly sweep and attract the activated sample until the surface of the strong magnet no longer attracts any magnetic substances, at which point the iron removal is complete.

[0011] b. Alkali washing

[0012] In step a, potassium hydroxide with a mass fraction of 1% to 5% is added to the iron-removed sample. Further addition of potassium hydroxide with a mass fraction of 1% to 3% results in a potassium hydroxide to activated carbon volume ratio of 5:1 to 20:1 (v / m), i.e., 5 to 20 parts potassium hydroxide are added to 1 part activated carbon. Preferably, the volume ratio of potassium hydroxide to activated carbon is 15:1. The sample with added potassium hydroxide is placed in a reaction vessel and ultrasonically and heated with stirring. The reaction vessel is lined with polytetrafluoroethylene to prevent corrosion from acids or alkalis during the reaction, which could introduce reaction impurities into the activated carbon. The reaction vessel also has ultrasonic... Combined with heating and stirring functions, the reaction rate is improved and the time is shortened by using ultrasound and heating and stirring. In the closed environment of the reactor, the temperature is increased to 30-60°C at a rate of 1-5°C / min while mechanically stirring at 100-400 rpm. After reaching the preset temperature, ultrasound is performed for 30-60 min. After ultrasound, the temperature is increased to 120-150°C at a rate of 3-10°C / min and stirred at this temperature for 2-12 h. This step involves two hydrothermal treatments and ultrasound treatment during hydrothermal treatment, which actively removes impurities such as silicates and phosphates from the activated carbon through the coupling of ultrasound and hydrothermal treatment.

[0013] c. Cooling water wash

[0014] After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water.

[0015] d, pickling

[0016] Similar to the alkaline washing operation in step b, add 5% to 20% hydrochloric acid to the sample obtained in step c. The volume ratio of hydrochloric acid to activated carbon is 5:1 to 20:1 (v / m). Preferably, the volume ratio of hydrochloric acid to activated carbon is 15:1. Place the sample with added hydrochloric acid in a reaction vessel, sonicate and heat and stir. In the closed environment of the reaction vessel, mechanically stir at 100 to 400 rpm while heating at a rate of 1 to 5 °C / min to 30 to 60 °C. After reaching the preset temperature, sonicate for 30 to 60 min. After sonication, heat to 120 to 150 °C at a rate of 3 to 10 °C / min and maintain this temperature for stirring for 2 to 12 h.

[0017] e. Secondary cooling water wash

[0018] After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water.

[0019] f, Drying

[0020] The moistened activated carbon after centrifugation and dehydration in step e is dried at 120~150℃ for 3~10h, and then the product quality is inspected.

[0021] g, packaging

[0022] The dried and qualified activated carbon from step f is then sieved and packaged.

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

[0024] This invention discloses a method for purifying activated carbon for capacitors. Under the combined action of ultrasound and mechanical stirring, the material and liquid are always in a state of relative motion, which can accelerate the solid-liquid mass transfer efficiency and shorten the reaction cycle. This method can produce activated carbon with ash content below 0.1% and iron content below 50 ppm from different types of carbon-containing materials using different production processes, meeting the standards for activated carbon used in supercapacitors.

[0025] By combining physical iron removal, ultrasonic and mechanical stirring, and hydrothermal coupling, activated carbon is deeply purified, improving its purity and significantly shortening the production cycle. This method has a wide range of applications and can process activated carbon made from biomass-based activated carbon, petroleum-based activated carbon, and activated carbon prepared from coal chemical by-products (coal tar pitch). It can be used for activated carbon prepared by both physical and chemical activation methods, making it suitable for widespread application. Implementation

[0026] Specific embodiments of the present invention will be described below. Example 1

[0027] The present invention provides a method for purifying capacitor-activated carbon, comprising the following steps:

[0028] a) Physical iron removal

[0029] After alkali activation, the coconut shell activated carbon sample was subjected to physical removal of magnetic substances such as iron and nickel under the action of a strong magnet. Specifically, the strong magnet was used to repeatedly sweep and attract the activated sample until the surface of the strong magnet no longer attracted any magnetic substances, at which point the iron removal was completed.

[0030] b. Alkali washing

[0031] In step a, 1% potassium hydroxide by mass is added to the iron-removed sample. Taking 20g of activated carbon as an example, the volume-to-mass ratio of potassium hydroxide to activated carbon is 15:1 (v / m), that is, 15 parts of potassium hydroxide are added to 1 part of activated carbon. The sample with added potassium hydroxide is placed in a reaction vessel and ultrasonically and heated and stirred. The reaction vessel is lined with polytetrafluoroethylene and has both ultrasonic and heating and stirring functions. The combination of ultrasonic and heating and stirring improves the reaction rate and shortens the time. In the sealed environment of the reaction vessel, the temperature is increased to 60°C at a rate of 5°C / min while mechanically stirring at 300 rpm. After reaching the preset temperature, ultrasonication is performed for 60 min. After ultrasonication, the temperature is increased to 130°C at a rate of 5°C / min and stirred at this temperature for 6 h.

[0032] c. Cooling water wash

[0033] After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water.

[0034] d, pickling

[0035] Add 9% hydrochloric acid to the sample obtained in step c. The volume ratio of hydrochloric acid to activated carbon is 15:1 (v / m), that is, 15 parts hydrochloric acid are added to 1 part activated carbon. Place the sample with added hydrochloric acid in a reaction vessel, sonicate and heat and stir. In the closed environment of the reaction vessel, mechanically stir at 300 rpm and heat to 60°C at a heating rate of 5°C / min. After reaching the preset temperature, sonicate for 60 min. After sonication, heat to 130°C at a heating rate of 5°C / min and maintain at this temperature for 6 h.

[0036] e. Secondary cooling water wash

[0037] After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water.

[0038] f, Drying

[0039] The moistened activated carbon after centrifugation and dehydration in step e is dried at 130℃ for 5 hours, and then the product quality is inspected.

[0040] g, packaging

[0041] The dried and qualified activated carbon from step f is then sieved and packaged.

[0042] The activated carbon prepared by the above method was tested and found to have an ash content of 0.06%, which is less than 0.1%, and an iron content of 47 ppm, which is less than 50 ppm, meeting the standards for activated carbon used in supercapacitors. Example 2

[0043] The present invention provides a method for purifying capacitor-activated carbon, comprising the following steps:

[0044] a) Physical iron removal

[0045] After alkali activation, the coconut shell activated carbon sample was subjected to physical removal of magnetic substances such as iron and nickel under the action of a strong magnet. Specifically, the strong magnet was used to repeatedly sweep and attract the activated sample until the surface of the strong magnet no longer attracted any magnetic substances, at which point the iron removal was completed.

[0046] b. Alkali washing

[0047] In step a, 5% potassium hydroxide by mass is added to the iron-removed sample. Taking 20g of activated carbon as an example, the volume-to-mass ratio of potassium hydroxide to activated carbon is 5:1 (v / m). The sample with added potassium hydroxide is placed in a reaction vessel and ultrasonically and heated and stirred. The reaction vessel is lined with polytetrafluoroethylene and has both ultrasonic and heating / stirring functions. The combination of ultrasonic and heating / stirring improves the reaction rate and shortens the time. In the sealed environment of the reaction vessel, the temperature is increased to 30℃ at a rate of 1℃ / min while mechanically stirring at 100rpm. After reaching the preset temperature, ultrasonication is performed for 50min. After ultrasonication, the temperature is increased to 150℃ at a rate of 3℃ / min and stirred at this temperature for 2h.

[0048] c. Cooling water wash

[0049] After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water.

[0050] d, pickling

[0051] Add 20% hydrochloric acid to the sample obtained in step c. The volume ratio of hydrochloric acid to activated carbon is 5:1 (v / m). Place the sample with added hydrochloric acid in a reaction vessel, sonicate and heat and stir. In the closed environment of the reaction vessel, mechanically stir at 100 rpm and heat to 30°C at a rate of 1°C / min. After reaching the preset temperature, sonicate for 50 min. After sonication, heat to 150°C at a rate of 3°C / min and maintain this temperature for stirring for 2 h.

[0052] e. Secondary cooling water wash

[0053] After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water.

[0054] f, Drying

[0055] The moistened activated carbon after centrifugation and dehydration in step e is dried at 100℃ and then subjected to product quality inspection.

[0056] g, packaging

[0057] The dried and qualified activated carbon from step f is then sieved and packaged.

[0058] The activated carbon prepared by the above method was tested and found to have an ash content of 0.09%, which is less than 0.1%, and an iron content of 45 ppm, which is less than 50 ppm, meeting the standards for activated carbon used in supercapacitors.

[0059] Both Example 1 and Example 2 used the same raw materials for purification. Through physical iron removal, ultrasonic combined with mechanical stirring, and hydrothermal coupling, the activated carbon obtained by both examples can meet the standards for activated carbon used in supercapacitors. Comparing Example 1 and Example 2, the ash content of Example 1 is lower than that of Example 2, while the iron content is not significantly different. Example 1 is superior to Example 2. Example 3

[0060] The present invention provides a method for purifying capacitor-activated carbon, comprising the following steps:

[0061] a) Physical iron removal

[0062] Using petroleum coke as raw material, the sample is activated by alkali and then physically removed from magnetic substances such as iron and nickel under the action of a strong magnet. Specifically, the strong magnet is used to repeatedly sweep and attract the activated sample. When the surface of the strong magnet no longer attracts magnetic substances, the iron removal is completed.

[0063] The remaining steps b to g are completely consistent with those in Example 1.

[0064] The activated carbon prepared by the above method was tested and found to have an ash content of 0.03%, which is much lower than 0.1%, and an iron content of 36 ppm, which is lower than 50 ppm, meeting the standards for activated carbon used in supercapacitors. Example 4

[0065] The present invention provides a method for purifying capacitor-activated carbon, comprising the following steps:

[0066] a) Physical iron removal

[0067] Using phenolic resin as raw material, the sample is activated by alkali and then physically removed from magnetic substances such as iron and nickel under the action of a strong magnet. Specifically, the strong magnet is used to repeatedly sweep and attract the activated sample. When the surface of the strong magnet no longer attracts magnetic substances, the iron removal is completed.

[0068] The remaining steps b to g are completely consistent with those in Example 1.

[0069] The activated carbon prepared by the above method was tested and found to have an ash content of 0.01%, which is far below 0.1%, and an iron content of 27 ppm, which is below 50 ppm, meeting the standards for activated carbon used in supercapacitors. Example 5

[0070] The present invention provides a method for purifying capacitor-activated carbon, comprising the following steps:

[0071] a) Physical iron removal

[0072] After physical activation, the coconut shell activated carbon sample was subjected to physical removal of magnetic substances such as iron and nickel under the action of a strong magnet. Specifically, the strong magnet was used to repeatedly sweep and attract the activated sample until the surface of the strong magnet no longer attracted any magnetic substances, at which point the iron removal was completed.

[0073] The remaining steps b to g are completely consistent with those in Example 1.

[0074] The activated carbon prepared by the above method was tested and found to have an ash content of 0.08%, which is much lower than 0.1%, and an iron content of 49 ppm, which is lower than 50 ppm, meeting the standards for activated carbon used in supercapacitors.

[0075] Comparing Examples 1, 3, 4, and 5, the four schemes differ only in the raw materials. Among them, Example 4 has the lowest ash and iron content, and uses phenolic resin as the raw material, resulting in the best effect.

[0076] The scope of protection claimed by this invention is not limited to the specific embodiments described above. Moreover, for those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for purifying capacitor-activated carbon, characterized in that: Includes the following steps: a) Physical iron removal The activated sample undergoes physical removal of magnetic substances under the action of a strong magnet; b. Alkali washing Add 1% to 5% potassium hydroxide by mass to the iron-removed sample in step a. Place the sample with added potassium hydroxide in a reaction vessel and sonicate and heat and stir. In the closed environment of the reaction vessel, heat to 30 to 60°C while mechanically stirring. After reaching the preset temperature, sonicate. After sonication, heat to 120 to 150°C and maintain at this temperature for 2 to 12 hours. Perform hydrothermal treatment twice and sonicate during hydrothermal treatment. c. Cooling water wash After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water. d, pickling Add 5% to 20% hydrochloric acid to the sample obtained in step c, place the sample with added hydrochloric acid in a reaction vessel, sonicate and heat and stir; in the closed environment of the reaction vessel, heat to 30 to 60°C while mechanically stirring, sonicate after reaching the preset temperature, and heat to 120 to 150°C after sonication, and maintain at this temperature for 2 to 12 hours. e. Secondary cooling water wash After the reaction vessel cools to room temperature, it is washed with deionized water until the pH of the solution is neutral, and then centrifuged to remove water. f, Drying The moist activated carbon after centrifugation and dehydration in step e is dried at 120~150℃ for 3~10h, and then the product quality is inspected. g, packaging The dried and qualified activated carbon from step f is then sieved and packaged.

2. The method for purifying capacitor-activated carbon according to claim 1, characterized in that: The reactors in steps b and d are lined with polytetrafluoroethylene and have both ultrasonic and heating / stirring functions.

3. The method for purifying capacitor-activated carbon according to claim 1, characterized in that: In step b, the volume-to-mass ratio of potassium hydroxide to activated carbon is 5:1 to 20:1; in step d, the volume-to-mass ratio of hydrochloric acid to activated carbon is 5:1 to 20:

1.

4. The method for purifying capacitor-activated carbon according to claim 1, characterized in that: In steps b and d, the stirring speed is 100~400 rpm.

5. The method for purifying capacitor-activated carbon according to claim 1, characterized in that: In steps b and d, the temperature is increased to 30-60℃ at a heating rate of 1-5℃ / min, and the temperature is increased to 120-150℃ at a heating rate of 3-10℃ / min.

6. The method for purifying capacitor-activated carbon according to claim 1, characterized in that: In step a, a strong magnet is used to repeatedly sweep and attract the activated sample. When the surface of the strong magnet no longer attracts magnetic substances, the iron removal is completed.

7. The method for purifying capacitive activated carbon according to claim 1, characterized in that: In steps b and d, in a sealed environment of the reactor, the temperature is increased to 60°C at a rate of 5°C / min while mechanically stirring at 300 rpm. After reaching the preset temperature, the reactor is sonicated for 60 min. After sonication, the temperature is increased to 130°C at a rate of 5°C / min and stirred at this temperature for 6 h.

8. The method for purifying capacitor-activated carbon according to claim 1, characterized in that: In step b, the volume ratio of potassium hydroxide to activated carbon is 15:1, and in step d, the volume ratio of hydrochloric acid to activated carbon is 15:1.