Biomass activated carbon as well as preparation method and application thereof

Abstract

The invention relates to biomass activated carbon and a preparation method and application thereof, and relates to the technical field of activated carbon materials.The preparation method comprises the following steps that biomass raw materials are pretreated and then soaked with a phosphoric acid solution, and first biomass is obtained; cooking and drying the first biomass, and then carrying out medium-temperature carbonization treatment to obtain a first carbide; carrying out phosphoric acid removal treatment and drying on the first carbide, and then mixing and crushing the first carbide with an alkali substance to obtain a second carbide; the second carbide is subjected to high-temperature activation treatment, alkali removal treatment, drying and smashing, and the biomass activated carbon is obtained. The super activated carbon with ultrahigh specific surface area, high porosity and high mesoporous aperture is prepared by adopting a multi-stage treatment method, so that the use requirements of a super capacitor, a lead-carbon battery and hydrogen storage energy are met, and the super activated carbon has wide practical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of activated carbon materials, and in particular to a biomass activated carbon and a preparation method and application thereof. Background Art

[0002] The current market urgently needs activated carbon materials with ultra-high specific surface area, high porosity and high mesoporous properties. These materials play a key role in the manufacture of supercapacitors, the construction of negative electrodes for lead-carbon batteries and activated carbon materials for hydrogen storage. Unfortunately, such high-end activated carbon materials in China mainly rely on imports, and domestic self-sufficiency is seriously insufficient.

[0003] Activated carbon products on the market can be roughly divided into several categories according to the different raw materials, such as wood (including fruit shells), polymer-based and coal-based. However, the continuous reduction of forest area around the world, especially the increasing depletion of forest resources available for industrial logging, poses a severe challenge to the activated carbon industry.

[0004] At the same time, environmental pollution has always been an important factor restricting social and economic development, and has had a profound impact on people's production and life. Therefore, how to efficiently utilize existing resources and reduce environmental pollution has become a major issue facing researchers around the world.

[0005] In many areas, rice husks are directly burned, which not only causes environmental pollution but also greatly wastes this precious biomass resource.

[0006] In summary, exploring new ways to prepare high-performance activated carbon using agricultural waste such as rice husks as raw materials will not only help alleviate the pressure on forest resources and reduce environmental pollution, but also achieve resource recycling and sustainable economic development. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a biomass activated carbon and a preparation method and application thereof.

[0008] In a first aspect, the present invention provides a method for preparing biomass activated carbon, the preparation method comprising the following steps:

[0009] The biomass raw material is pretreated and then soaked in a phosphoric acid solution to obtain a first biomass;

[0010] The first biomass is steamed and dried, and then subjected to medium-temperature carbonization treatment to obtain a first carbonized product;

[0011] The first carbonized product is subjected to a dephosphorization treatment and drying, and then mixed with an alkaline substance and crushed to obtain a second carbonized product;

[0012] The second carbonized product is subjected to high temperature activation treatment, and then subjected to alkali removal treatment, drying and pulverization to obtain the biomass activated carbon.

[0013] Furthermore, the biomass raw material includes at least one of rice stalks, bamboo leaves, bamboo, wheat straw, peanut shells and rice husks; the pretreatment step includes the following processes: screening the biomass raw material to remove impurities and drying it to a moisture content of ≤3wt%; the soaking working condition parameters include: the mass fraction concentration of the phosphoric acid solution is 35%, the soaking temperature is room temperature, and the soaking time is 12 to 24 hours.

[0014] Furthermore, the working condition parameters of the cooking and drying include: a cooking temperature of 110-120° C., a cooking time of 1-3 hours; and drying after cooking to a moisture content of ≥10-13wt%.

[0015] Furthermore, the working condition parameters of the medium-temperature carbonization treatment include: heating the material from room temperature to 130°C and keeping it for 20 minutes, heating from 130°C to 300°C and keeping it for 20 minutes, heating from 300°C to 400°C and keeping it for 30 minutes, heating from 400°C to 500°C-600°C and keeping it for 150 minutes. After the insulation is completed, the material is cooled down with the furnace to below 50°C for the next process.

[0016] Furthermore, the terminal holding temperature of the medium-temperature carbonization treatment is 550°C.

[0017] Furthermore, the working condition parameters of the dephosphorylation treatment and drying include: soaking the material with ultrapure water, stirring during the soaking process, filtering after each soaking for 3 hours, and repeatedly washing several times until the pH is 7; drying to a moisture content of ≤3wt% after dephosphorylation treatment.

[0018] Furthermore, the weight ratio of the first carbonized product to the alkaline substance after phosphoric acid treatment and drying is 1:(3-5); and the crushed particle size of the second carbonized product is 10 microns to 15 microns.

[0019] Furthermore, the working condition parameters of the high-temperature activation treatment include: the material is heated from room temperature to 150°C and kept for 20 minutes, from 150°C to 300°C and kept for 20 minutes, from 300°C to 450°C and kept for 30 minutes, from 450°C to 600°C and kept for 30 minutes, from 600°C to 700°C and kept for 40 minutes, from 700°C to 780°C to 900°C and kept for 150 minutes, and after the insulation is completed, the material is cooled down to 50°C with the furnace for the next process;

[0020] The working condition parameters of the de-alkali treatment include: first heating the ultrapure water to 90°C to 100°C, soaking the activated material with the ultrapure water at 90°C to 100°C, stirring during the soaking process, soaking for 2h to 3h each time, filtering after each soaking and washing, and repeatedly washing several times until the pH is 7; drying after the de-alkali treatment to a moisture content of ≤1wt%.

[0021] Furthermore, the terminal holding temperature of the high temperature activation treatment is 850°C.

[0022] Furthermore, the heating rates of the medium-temperature carbonization treatment and the high-temperature activation treatment are both 4-8°C / min.

[0023] In a second aspect, the present invention provides a biomass activated carbon, which is prepared by the preparation method described in any one of the first aspects.

[0024] Furthermore, the physical and chemical property parameters of the biomass activated carbon include: a specific surface area of ​​2530 m2 to 3100 m2 / g, a mesoporosity of 68% to 81%, and a porosity of 2.30 ml / g to 3.05 ml / g.

[0025] In a third aspect, the present invention provides the use of the biomass activated carbon described in any one of the second aspects in the preparation of capacitor carbon electrode materials, lead-carbon battery carbon materials, and hydrogen physical storage materials.

[0026] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art:

[0027] The embodiment of the present invention provides a biomass activated carbon and a preparation method and application thereof. The present invention adopts a multi-stage treatment method to prepare a super activated carbon with ultra-high specific surface area, high porosity, and high medium porosity (2nm~50nm) to meet the use requirements of supercapacitors, lead-carbon batteries, and hydrogen storage energy, and has wide practical application value. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0030] In a first aspect, the present invention provides a method for preparing biomass activated carbon, the preparation method comprising the following steps:

[0031] The biomass raw material is pretreated and then soaked in a phosphoric acid solution to obtain a first biomass;

[0032] The first biomass is steamed and dried, and then subjected to medium-temperature carbonization treatment to obtain a first carbonized product;

[0033] The first carbonized product is subjected to a dephosphorization treatment and drying, and then mixed with an alkaline substance and crushed to obtain a second carbonized product;

[0034] The second carbonized product is subjected to high temperature activation treatment, and then subjected to alkali removal treatment, drying and pulverization to obtain the biomass activated carbon.

[0035] The present invention adopts a multi-stage treatment method to prepare a super activated carbon with ultra-high specific surface area, high porosity, and high and medium porosity (2nm-50nm) to meet the use requirements of supercapacitors, lead-carbon batteries, and hydrogen storage energy, and has wide practical application value.

[0036] The present invention relates to a method for preparing ultra-high specific surface area and high-medium porosity activated carbon prepared from biomass materials after multiple treatments. The biomass used is such as bamboo leaves, bamboo, rice husks, rice straws and other materials, which are subjected to crushing treatment, screening treatment, drying treatment, soaking treatment, drying treatment, medium-high carbonization treatment, acid washing treatment, drying treatment, mixed material treatment, crushing treatment, high-temperature activation treatment, alkali washing treatment, cleaning treatment, drying treatment, crushing treatment, finished product packaging and other processes. In some specific embodiments, for example, biomass rice straw, bamboo leaves, bamboo straw and peanut shells (first crushed into 3mm-6mm particles), rice husks, etc.; taking rice husks as an example:

[0037] 1. First sieve to remove impurities;

[0038] 2. Dry to moisture ≤ 3%;

[0039] 3. Soaking in phosphoric acid solution to remove impurities: Prepare a 35% phosphoric acid solution with ultrapure water, and soak the rice husks or rice straws in the phosphoric acid solution for 12 hours;

[0040] 4. Steaming and drying pretreatment: soak the material after impurity removal in phosphoric acid, and then steam and dry it at a temperature of 110-120°C, and dry it until the moisture content is ≥10-13%;

[0041] 5. Medium-temperature carbonization treatment: The dried phosphoric acid-impregnated material is subjected to medium- and high-temperature carbonization treatment, wherein the material is heated from room temperature to 130°C for 20 minutes, from 130°C to 300°C for 20 minutes, from 300°C to 400°C for 30 minutes, from 400°C to 500°C-600°C for 150 minutes, and after the insulation, the material is cooled down to below 50°C with the furnace for the next process;

[0042] 6. Dephosphorize the phosphate carbonized material by soaking it in ultrapure water, stirring it during the soaking process, filtering it after each soaking for 3 hours, and repeating this method for cleaning several times.

[0043] 7. After the carbonized product is cleaned after acid removal, the cleaning process ends when the cleaning material reaches neutrality and the pH value is 7;

[0044] 8. Dry the cleaned carbonized product until the moisture content is ≤3%;

[0045] 9. Mix the carbonized material with the alkaline substance; the ratio of the carbonized material to the alkali (KOH or NaOH) is 1:4, and the two materials are mixed, and the mixing process must be uniform;

[0046] 10. The carbon material and the alkali mixture are crushed and mixed; the uniformly mixed materials are mixed and crushed, and the crushed particle size is 10 microns to 15 microns.

[0047] 11. Carry out high-temperature activation treatment on the carbonized material and alkali mixture, the treatment method is: heat the carbon alkali material from room temperature to 150°C and keep it for 20 minutes, heat it from 150°C to 300°C and keep it for 20 minutes, heat it from 300°C to 450°C and keep it for 30 minutes, heat it from 450°C to 600°C and keep it for 30 minutes, heat it from 600°C to 700°C and keep it for 40 minutes, heat it from 700°C to 780°C~900°C and keep it for 150 minutes. After the insulation is completed, cool it down to 50°C with the furnace for the next process;

[0048] 12. Remove alkali from the activated mixture; first heat the ultrapure water to 90℃~100℃, soak the activated material in 90℃~100℃ ultrapure water, stir during the soaking process, soak for 2h~3h each time, filter after each soaking and washing. Soak and wash several times in the same way.

[0049] 13. Wash the activated material after alkali removal until the rice husk activated carbon water is neutral and the pH value is 7. The washing is completed and the material is super activated carbon.

[0050] 14. After cleaning, the rice husk activated carbon material is dried. When the moisture content of the rice husk activated carbon material is ≤1%, the drying is completed;

[0051] 15. The super activated carbon after drying is crushed and crushed according to the requirements of the object to be used, and the super activated carbon material processed according to the requirements of the object to be used is packaged. The prepared activated carbon has a specific surface area of ​​2530㎡~3100㎡ / g, a mesoporosity of 68%~81%, and a porosity of 2.30ml / g~3.05ml / g. The present invention uses rice as the raw material of activated carbon, and the prepared activated carbon is mainly used for supercapacitor carbon electrode materials, lead-carbon battery carbon materials, and hydrogen physical storage materials.

[0052] In a second aspect, the present invention provides a biomass activated carbon, which is prepared by the preparation method described in any one of the first aspects.

[0053] In some specific embodiments, the physical and chemical property parameters of the biomass activated carbon include: a specific surface area of ​​2530 m2 to 3100 m2 / g, a mesoporosity of 68% to 81%, and a porosity of 2.30 ml / g to 3.05 ml / g.

[0054] In a third aspect, the present invention provides the use of the biomass activated carbon described in any one of the second aspects in the preparation of capacitor carbon electrode materials, lead-carbon battery carbon materials, and hydrogen physical storage materials.

[0055] It should be noted that, unless otherwise specified or described, the components and raw materials involved in the biomass activated carbon and its preparation method and application provided in the embodiments of the present invention can be directly commercially available products or homemade according to existing preparation processes. At the same time, the operation steps involved in the biomass activated carbon and its preparation method and application provided in the embodiments of the present invention can be carried out in a conventional manner in the art or using existing equipment unless otherwise specified or described, and will not be described one by one here.

[0056] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0057] Example 1

[0058] This example provides a biomass activated carbon, taking rice husk as an example, the preparation method of the biomass activated carbon includes the following steps:

[0059] 1. First sieve to remove impurities;

[0060] 2. Dry to moisture ≤ 3%;

[0061] 3. Soaking in phosphoric acid solution to remove impurities: Prepare a 35% phosphoric acid solution with ultrapure water, and soak the rice husks in the phosphoric acid solution for 12 hours;

[0062] 4. Steaming and drying pretreatment: the material after impurity removal treatment by soaking in phosphoric acid is subjected to steaming and drying treatment at a temperature of 105°C for 2 hours and dried to a moisture content of 13%;

[0063] 5. Medium-temperature carbonization treatment: The dried phosphoric acid-impregnated material is subjected to medium- and high-temperature carbonization treatment, with a heating rate of 5°C / min. The treatment method is: heating the material from room temperature to 130°C and keeping it for 20 minutes, from 130°C to 300°C and keeping it for 20 minutes, from 300°C to 400°C and keeping it for 30 minutes, from 400°C to 550°C and keeping it for 150 minutes. After the insulation is completed, the material is cooled down to below 50°C with the furnace for the next process;

[0064] 6. Remove phosphoric acid from the phosphate carbonized material by soaking it in ultrapure water, stirring it during the soaking process, filtering it after each soaking for 3 hours, and repeating this method for several times;

[0065] 7. After the carbonized product is cleaned after acid removal, the cleaning process ends when the cleaning material reaches neutrality and the pH value is 7;

[0066] 8. Dry the cleaned carbonized product until the moisture content is ≤3%;

[0067] 9. The carbonized material is mixed with the alkaline substance; the weight ratio of the carbonized material to the alkali (KOH) is 1:4, and the two materials are mixed, and the mixing process must be uniform;

[0068] 10. The carbon material and the alkali mixture are crushed and mixed; the uniformly mixed materials are mixed and crushed, and the crushed particle size is 10 microns to 15 microns;

[0069] 11. Carry out high-temperature activation treatment on the carbonized material and alkali mixture at a heating rate of 5°C / min. The treatment method is: heat the carbon alkali material from room temperature to 150°C and keep it for 20 minutes, heat it from 150°C to 300°C and keep it for 20 minutes, heat it from 300°C to 450°C and keep it for 30 minutes, heat it from 450°C to 600°C and keep it for 30 minutes, heat it from 600°C to 700°C and keep it for 40 minutes, heat it from 700°C to 850°C and keep it for 150 minutes. After the insulation is completed, cool it down to 50°C with the furnace for the next process;

[0070] 12. The activated mixed material is subjected to alkali removal treatment; first, the ultrapure water used is heated to 100°C, and the activated material is soaked in 100°C ultrapure water, and the material is stirred during the soaking process. Each soaking treatment lasts for 3 hours, and the material is filtered after each soaking and washing; the same soaking and washing are performed continuously for several times;

[0071] 13. Wash the activated material after alkali removal until the rice husk activated carbon water is neutral and the pH value is 7. The washing is completed and the material is super activated carbon;

[0072] 14. After cleaning, the rice husk activated carbon material is dried. When the moisture content of the rice husk activated carbon material is ≤1%, the drying is completed;

[0073] 15. The super activated carbon after drying is crushed according to the crushing specifications and the requirements of the object to be used. The super activated carbon material processed according to the requirements of the object to be used is packaged.

[0074] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 3100, high and medium porosity (2nm~50nm) is 81%, and porosity is 3.05ml / g.

[0075] Example 2

[0076] This example provides a biomass activated carbon and a preparation method thereof, which differs from Example 1 only in that: 1) the end temperature of the medium-temperature carbonization treatment of 550°C is adjusted to 500°C; 2) the end temperature of the high-temperature activation treatment of 850°C is adjusted to 900°C.

[0077] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 2753, high and medium porosity (2nm~50nm) is 72%, and porosity is 2.71ml / g.

[0078] Example 3

[0079] This example provides a biomass activated carbon and a preparation method thereof, which differs from Example 1 only in that: 1) the end temperature of the medium-temperature carbonization treatment of 550°C is adjusted to 600°C; 2) the end temperature of the high-temperature activation treatment of 850°C is adjusted to 780°C.

[0080] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 2530, high and medium porosity (2nm~50nm) is 68%, and porosity is 2.30ml / g.

[0081] Comparative Example 1

[0082] This example provides a biomass activated carbon and a preparation method thereof, which is different from Example 1 only in that the end point temperature of the medium-temperature carbonization treatment of Example 1 is adjusted from 550°C to 450°C; the remaining steps and parameters are the same.

[0083] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 2072, and high porosity (2nm~50nm) is 55%.

[0084] Comparative Example 2

[0085] This example provides a biomass activated carbon and a preparation method thereof, which differs from Example 1 only in that the terminal temperature of the high-temperature activation treatment of 850°C in Example 1 is adjusted to 1000°C; the remaining steps and parameters are the same.

[0086] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 2235, high and medium porosity (2nm~50nm) is 60%, and porosity is 1.93ml / g.

[0087] Comparative Example 3

[0088] This example provides a biomass activated carbon and a preparation method thereof, which differs from Example 1 only in that the terminal temperature of the high-temperature activation treatment of 850°C in Example 1 is adjusted to 730°C; the remaining steps and parameters are the same.

[0089] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 1750, high and medium porosity (2nm~50nm) is 51%, and porosity is 1.76ml / g.

[0090] Comparative Example 4

[0091] This example provides a biomass activated carbon and a preparation method thereof, which is different from Example 1 only in that the weight ratio of the carbonized material to the alkali (KOH) in Example 1 is adjusted from 1:4 to 1:5; the remaining steps and parameters are the same.

[0092] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 2756, high and medium porosity (2nm~50nm) is 58%, and porosity is 2.45ml / g.

[0093] Comparative Example 5

[0094] This example provides a biomass activated carbon and a preparation method thereof, which is different from Example 1 only in that the weight ratio of the carbonized material to the alkali (KOH) in Example 1 is adjusted from 1:4 to 1:3; the remaining steps and parameters are the same.

[0095] The physical and chemical properties of the biomass activated carbon obtained in this example are as follows: specific surface area (㎡ / g) is 2540, high and medium porosity (2nm~50nm) is 52%, and porosity is 1.81ml / g.

[0096] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing biomass activated carbon, characterized in that: The preparation method comprises the following steps: The biomass raw material is pretreated and then soaked in a phosphoric acid solution to obtain a first biomass; The first biomass is steamed and dried, and then subjected to medium-temperature carbonization treatment to obtain a first carbonized product; The first carbonized product is subjected to a dephosphorization treatment and drying, and then mixed with an alkaline substance and crushed to obtain a second carbonized product; The second carbonized product is subjected to high temperature activation treatment, and then subjected to alkali removal treatment, drying and pulverization to obtain the biomass activated carbon.

2. The method for preparing biomass activated carbon according to claim 1, characterized in that: The biomass raw material comprises at least one of rice straw, bamboo leaves, bamboo, wheat straw, peanut shells and rice husks; The pre-processing step The process includes the following steps: screening the biomass raw materials to remove impurities, and drying them to a moisture content of ≤3wt%; The working condition parameters of the immersion include: the mass fraction concentration of the phosphoric acid solution is 35%, the immersion temperature is room temperature, and the immersion time is 12 to 24 hours.

3. The method for preparing biomass activated carbon according to claim 1, characterized in that: The working condition parameters of the cooking and drying include: a cooking temperature of 110-120° C., a cooking time of 1-3 hours; and drying after cooking until the moisture content is ≥10-13wt%.

4. The method for preparing biomass activated carbon according to claim 1, characterized in that: The working condition parameters of the medium-temperature carbonization treatment include: heating the material from room temperature to 130°C and keeping it for 20 minutes, heating from 130°C to 300°C and keeping it for 20 minutes, heating from 300°C to 400°C and keeping it for 30 minutes, heating from 400°C to 500°C-600°C and keeping it for 150 minutes. After the insulation is completed, the material is cooled down to below 50°C with the furnace for the next process.

5. The method for preparing biomass activated carbon according to claim 1, characterized in that: The working condition parameters of the dephosphorylation treatment and drying include: soaking the material with ultrapure water, stirring during the soaking process, filtering after each soaking for 3 hours, and repeatedly washing several times until the pH value is 7; and drying to a moisture content of ≤3wt% after the dephosphorylation treatment.

6. The method for preparing biomass activated carbon according to claim 1, characterized in that: The weight ratio of the first carbonized product to the alkaline substance after phosphoric acid treatment and drying is 1:(3-5); the crushed particle size of the second carbonized product is 10 microns to 15 microns.

7. The method for preparing biomass activated carbon according to claim 1, characterized in that: The working condition parameters of the high temperature activation treatment include: the material is heated from room temperature to 150°C and kept for 20 minutes, from 150°C to 300°C and kept for 20 minutes, from 300°C to 450°C and kept for 30 minutes, from 450°C to 600°C and kept for 30 minutes, from 600°C to 700°C and kept for 40 minutes, from 700°C to 780°C to 900°C and kept for 150 minutes, and after the end of the heat preservation, the material is cooled down to 50°C with the furnace for the next process; The working condition parameters of the de-alkali treatment include: first heating the ultrapure water to 90°C to 100°C, soaking the activated material with the ultrapure water at 90°C to 100°C, stirring during the soaking process, soaking for 2h to 3h each time, filtering after each soaking and washing, and repeatedly washing several times until the pH is 7; drying after the de-alkali treatment to a moisture content of ≤1wt%.

8. A biomass activated carbon, characterized in that: The biomass activated carbon is prepared by the preparation method described in any one of claims 1 to 7.

9. The biomass activated carbon according to claim 8, characterized in that: The physical and chemical property parameters of the biomass activated carbon include: a specific surface area of ​​2530 m2 to 3100 m2 / g, a mesoporosity of 68% to 81%, and a porosity of 2.30 ml / g to 3.05 ml / g.

10. Use of the biomass activated carbon according to any one of claims 8 to 9 in the preparation of capacitor carbon electrode materials, lead-carbon battery carbon materials, and hydrogen physical storage materials.