Biomass activated carbon and preparation method thereof

Abstract

The invention discloses biomass activated carbon and a preparation method thereof.The preparation method comprises the steps that a raw material mixture containing biomass raw materials and water is placed in a closed reactor to be subjected to a hydrothermal carbonization reaction, and a solid-liquid mixture is obtained; separating out a solid-phase product in the solid-liquid mixture, and carrying out self-water pyrolysis activation reaction on the solid-phase product in a protective gas atmosphere to obtain the biomass activated carbon. In the application, a carbon-rich product with moisture uniformly distributed in the biomass, rich oxygen-containing functional groups and carbon as a main body can be obtained in the hydrothermal carbonization step, the moisture can be vaporized as an endogenous activator in the pyrolysis process, and in combination with the synergistic effect of gases such as oxycarbide and the like generated by biomass pyrolysis and internal thermal stress, the carbon-rich product can be obtained; and efficient and uniform activation is facilitated, so that the biomass activated carbon with a developed pore structure can be prepared from a blocky biomass raw material.

Description

Technical Field

[0001] The present application relates to the technical field of biomass-based activated carbon material preparation, and more specifically, to biomass activated carbon and a preparation method thereof. Background Art

[0002] As a porous material, activated carbon has the characteristics of large specific surface area, developed pore structure, easy chemical modification, low economic cost and good renewability, and has important industrial application value. At present, although the sources of activated carbon raw materials are extensive, coal-based activated carbon still dominates, with a specific surface area of ​​up to 1000m 2 / g, has been widely used in water treatment, air purification, energy storage materials, and catalyst carriers. However, with the increasing scarcity of fossil resources and fewer and fewer high-quality coals, coal-based activated carbon has limitations in the preparation of high-performance pure activated carbon products. In addition, as a "positive carbon" product, coal-based activated carbon faces many challenges in environmental protection and sustainable resource utilization. As the only renewable carbon resource, biomass resources are an ideal choice to replace traditional fossil raw materials. Compared with coal-based activated carbon, activated carbon made from biomass can not only significantly reduce greenhouse gas emissions, but also effectively fix carbon for long-term storage. In addition, biomass activated carbon also has a developed pore structure and is rich in oxygen-containing functional groups such as hydroxyl groups, and has special adsorption application potential.

[0003] Existing activated carbon preparation mainly includes physical and chemical methods. Among them, the specific surface area and total pore volume of activated carbon obtained by the physical method are relatively small, which is difficult to meet the needs of some scenarios; the chemical method mostly uses acid, alkali and other reagents to react with biomass raw materials. The use of these reagents is prone to secondary pollution and increases the complexity of post-processing and equipment maintenance costs. At the same time, both physical and chemical methods require the biomass raw materials to be crushed into small particles to improve the contact efficiency between the activator and the biomass raw materials, which is difficult to promote and apply in large-scale continuous industrial production. Therefore, it is of great significance to develop a green and low-cost biomass activated carbon preparation technology suitable for blocky biomass raw materials.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] The purpose of the present application is to provide biomass activated carbon and a preparation method thereof, so as to overcome the problem that the prior art requires the biomass raw materials to be crushed to improve the activation uniformity and cannot directly process the blocky biomass raw materials.

[0006] This application is implemented as follows:

[0007] In a first aspect, the present application provides a method for preparing biomass activated carbon, comprising:

[0008] placing a raw material mixture including a biomass raw material and water in a closed reactor for hydrothermal carbonization reaction to obtain a solid-liquid mixture;

[0009] The solid phase product in the solid-liquid mixture is separated, and the solid phase product is placed in a protective gas atmosphere to carry out a self-hydrothermal activation reaction to obtain the biomass activated carbon.

[0010] In an optional embodiment, the biomass raw material is a raw material containing lignocellulose.

[0011] In an optional embodiment, the hydrothermal carbonization reaction temperature is 140°C to 250°C, and the time is 4h to 24h;

[0012] Preferably, the hydrothermal carbonization reaction temperature is 140° C. to 220° C., and the time is 10 h to 16 h.

[0013] In an alternative embodiment, in the feedstock mixture, the water submerges the biomass feedstock.

[0014] In an optional embodiment, the shielding gas is an inert gas.

[0015] In an optional embodiment, during the self-hydrothermolysis activation reaction, a protective gas is introduced into the reactor carrying the solid phase product, and the flow rate of the protective gas is 10 mL / min to 300 mL / min, preferably 10 mL / min to 50 mL / min.

[0016] In an optional embodiment, the temperature of the self-hydrothermal activation reaction is 500°C to 1100°C, and the time is 0.5h to 4h;

[0017] Preferably, the temperature of the self-hydrothermolysis activation reaction is 850° C. to 1000° C., and the time is 0.5 h to 3 h.

[0018] In an optional embodiment, the heating rate of the self-hydrothermolysis activation reaction step is 2°C / min to 20°C / min, preferably 10°C / min to 20°C / min.

[0019] In a second aspect, the present application provides a biomass activated carbon prepared by the method for preparing biomass activated carbon described in any one of the aforementioned embodiments.

[0020] In an optional embodiment, the biomass activated carbon satisfies at least one of the following AC characteristics:

[0021] A. The specific surface area of ​​the biomass activated carbon is 100m 2 / g~3200m 2 / g;

[0022] B. The average pore size of the biomass activated carbon is 1nm to 2.5nm;

[0023] C. The micropores of the biomass activated carbon account for 77% to 98%.

[0024] This application has the following beneficial effects:

[0025] In the present application, the hydrothermal carbonization step is carried out in a closed reactor, and the pressure increases under hydrothermal conditions. The organic matter in the biomass raw material undergoes dehydration, decarboxylation and other reactions in a high-temperature and high-pressure water environment, and the solid phase in the solid-liquid mixture is a carbon-rich product with water evenly distributed inside the biomass, rich in oxygen-containing functional groups, and mainly carbon, which is subsequently recorded as hydrochar. In the process of self-hydrothermal pyrolysis activation, the inherent and relatively evenly distributed water in the hydrochar can be vaporized during the pyrolysis process as an endogenous activator, and combined with the synergistic effect of gases such as carbon oxides produced by the pyrolysis of biomass and internal thermal stress, it is conducive to achieving efficient and uniform activation, and thus it can be achieved that even with blocky biomass raw materials, biomass activated carbon with a developed pore structure can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 This is a flow chart for the preparation of biomass activated carbon in this application;

[0028] Figure 2 This is the SEM image of the activated carbon of Example 1;

[0029] Figure 3 N2 adsorption-desorption curve and pore size distribution curve of the activated carbon sample prepared in Example 1;

[0030] Among them, (a) is the N2 adsorption and desorption curve; (b) is the pore size distribution curve.

[0031] Figure 4 XRD pattern of the activated carbon sample prepared in Example 1;

[0032] Figure 5 This is the FTIR graph of the activated carbon sample prepared in Example 1. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0034] The present application provides a method for preparing biomass activated carbon, comprising:

[0035] placing a raw material mixture including a biomass raw material and water in a closed reactor for hydrothermal carbonization reaction to obtain a solid-liquid mixture;

[0036] The solid phase product in the solid-liquid mixture is separated, and the solid phase product is placed in a protective gas atmosphere to carry out a self-hydrothermal activation reaction to obtain the biomass activated carbon.

[0037] The present application achieves efficient and uniform activation by utilizing the inherent moisture in the hydrochar as an endogenous activator to vaporize during the pyrolysis process, and combining the synergistic effect of gases such as carbon oxides produced by the pyrolysis of biomass and internal thermal stress. Specifically, in the present application, the hydrothermal carbonization step is carried out in a closed reactor, and the pressure increases under hydrothermal conditions. The organic matter in the biomass raw material undergoes dehydration, decarboxylation and other reactions in a high-temperature and high-pressure water environment, and the solid phase in the solid-liquid mixture is obtained, that is, a carbon-rich product with water evenly distributed inside the biomass, rich in oxygen-containing functional groups, and mainly carbon, which is subsequently recorded as hydrochar. In the process of self-hydrothermal pyrolysis activation, the inherent and relatively evenly distributed moisture in the hydrochar can be vaporized during the pyrolysis process as an endogenous activator, and combined with the synergistic effect of gases such as carbon oxides produced by the pyrolysis of biomass and internal thermal stress, it is conducive to achieving efficient and uniform activation, and thus it can be achieved that even with blocky biomass raw materials, biomass activated carbon with a developed pore structure can be prepared. The present application does not need to crush the biomass raw materials into fine particles to improve the activation efficiency, solves the problem of low activation efficiency of large-sized biomass raw materials during the activation process, and is suitable for large-scale production.

[0038] In addition, no chemical reagents are added during the entire preparation process of the present application, and no post-processing such as pickling is required, so there is no secondary pollution and the equipment maintenance cost is reduced.

[0039] It should be noted that the preparation method of biomass activated carbon in the present application is not limited in applicable size, as long as the reactor has enough space to carry the biomass raw materials, there is no need to crush the common biomass materials into powder, which is conducive to simplifying the process; for the biomass raw materials, any raw materials that can be obtained in nature can be used.

[0040] In an optional embodiment, the biomass raw material is a raw material containing lignocellulose, specifically bamboo, wood, straw or other raw materials containing lignocellulose, such as bamboo chips, wood chips, straw residues and the like.

[0041] In an optional embodiment, the hydrothermal carbonization reaction temperature is 140°C to 250°C, and the time is 4h to 24h;

[0042] Preferably, the hydrothermal carbonization reaction temperature is 140° C. to 220° C., and the time is 10 h to 16 h.

[0043] During the hydrothermal carbonization stage, the hydrothermal carbonization temperature and time will affect the uniformity and pore structure of the activated carbon product. Too low a temperature or too short a time will lead to incomplete and uneven hydrothermal carbonization, while too high a temperature or too long a time will accelerate the decomposition process of the biomass and even cause it to over-decompose, resulting in a decrease in the yield of activated carbon.

[0044] In an optional embodiment, in the raw material mixture, water submerges the biomass raw material, which is beneficial to improving the uniformity of the activated carbon structure.

[0045] In an optional embodiment, the protective gas is an inert gas, such as nitrogen, argon, etc.

[0046] In an optional embodiment, during the self-hydrothermolysis activation reaction, a protective gas is introduced into the reactor carrying the solid phase product, and the flow rate of the protective gas is 10 mL / min to 300 mL / min, preferably 10 mL / min to 50 mL / min.

[0047] The presence of shielding gas can prevent the hydrochar from being oxidized, but the flow of shielding gas will take away the water vapor and other gases produced by pyrolysis in the hydrochar, which will further affect the pore structure. Therefore, the flow of shielding gas should not be too fast.

[0048] In an optional embodiment, the temperature of the self-hydrothermal activation reaction is 500°C to 1100°C, and the time is 0.5h to 4h;

[0049] Preferably, the temperature of the self-hydrothermolysis activation reaction is 850° C. to 1000° C., and the time is 0.5 h to 3 h.

[0050] In the hydrothermal activation stage, higher temperature and appropriately extended time are conducive to the increase of specific surface area and micropore ratio. Too high temperature or too long time will cause the pore structure to collapse, which will reduce the specific surface area.

[0051] In an optional embodiment, the heating rate of the self-hydrothermolysis activation reaction step is 2°C / min to 20°C / min, preferably 10°C / min to 20°C / min.

[0052] During the heating process, water vapor and other pyrolysis gases in the hydrochar will be gradually released. Therefore, rapid heating is beneficial to retaining water vapor and other pyrolysis gases in the hydrochar and promoting the formation of pore structure.

[0053] The embodiment of the present application also provides a biomass activated carbon, which is prepared by the preparation method of biomass activated carbon described in any one of the aforementioned embodiments.

[0054] In an optional embodiment, the biomass activated carbon satisfies at least one of the following AC characteristics:

[0055] A. The specific surface area of ​​the biomass activated carbon is 100m 2 / g~3200m 2 / g;

[0056] B. The average pore size of the biomass activated carbon is 1nm to 2.5nm;

[0057] C. The micropores of the biomass activated carbon account for 77% to 98%.

[0058] The biomass activated carbon preparation method of the present application has a simple preparation process and low cost, and can obtain key parameters of activated carbon such as larger specific surface area, micropore content and total pore volume, which is beneficial to its application in the removal of air and water pollutants.

[0059] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0060] Example 1

[0061] This embodiment provides a method for preparing biomass activated carbon, which specifically includes the following steps:

[0062] Step 1, weigh 5.2g of washed and air-dried bamboo pieces (single bamboo pieces of about 6*4*1cm), place them in a hydrothermal reactor, and then add aqueous solution until the bamboo raw material is completely immersed. Next, place the hydrothermal reactor in a forced air drying oven for heating, control the hydrothermal carbonization temperature to 180°C, and maintain the hydrothermal carbonization time for 10 hours. After the reaction is completed, cool naturally to room temperature, and then filter and separate the blend of hydrochar and aqueous solution.

[0063] Step 2: Place the separated hydrochar in a tubular furnace, introduce nitrogen at a flow rate of 10 mL / min, heat to 1000°C at a heating rate of 15°C / min, and activate at this temperature for 0.5 hours. After activation, start cooling, and continue to introduce nitrogen during the process. When the furnace temperature drops to 50°C, take out the activated carbon sample.

[0064] Step 3: Wash the activated carbon with clean water to remove water-soluble impurities such as soluble salts or incompletely reacted residues. The washed activated carbon is dried in an oven at 105°C to constant weight. After the sample is cooled to room temperature, it is weighed and stored to obtain an activated carbon sample. Its SEM, N2 adsorption and desorption curves, pore size distribution curves, XRD and FTIR graphs are shown in the figure below. Figure 2-5 shown.

[0065] The specific surface area of ​​the activated carbon is 1342.6 m 2 / g, the average pore size is 1.79nm, and the proportion of micropores is 97%.

[0066] The specific surface area is calculated by the BET (Brunauer-Emmett-Teller) method, the average pore size is analyzed by the DFT (density functional theory) theory, and the micropore ratio is calculated by micropore volume / total pore volume.

[0067] Example 2

[0068] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0069] Weigh 5.5 g of washed and air-dried bamboo blocks, set the hydrothermal carbonization temperature to 180 °C, the carbonization time to 10 hours, the heating rate of the pyrolysis activation process to 15 °C / min, the activation temperature to 1000 °C, the activation time to 3 hours, and the nitrogen flow rate to 10 mL / min.

[0070] The specific surface area of ​​the activated carbon prepared is 1956.1m 2 / g, the average pore size is 1.83nm, and the proportion of micropores is 98%.

[0071] Example 3

[0072] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0073] Weigh 5.3 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature is 220°C, the carbonization time is 10 hours, the heating rate of the pyrolysis activation process is 15°C / min, the activation temperature is 1000°C, the activation time is 1.75 hours, and the nitrogen flow rate is 10 mL / min.

[0074] The specific surface area of ​​the activated carbon prepared is 1617.2m 2 / g, the average pore size is 1.93nm, and micropores account for 94%.

[0075] Example 4

[0076] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0077] Weigh 3.6 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature was 180°C, the carbonization time was 10 hours, the heating rate of the pyrolysis activation process was 15°C / min, the activation temperature was 850°C, the activation time was 1.75 hours, and the nitrogen flow rate was 10 mL / min.

[0078] The specific surface area of ​​the prepared activated carbon is 1050.5m 2 / g, the average pore size is 1.79nm, and the proportion of micropores is 82%.

[0079] Example 5

[0080] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0081] Weigh 6.5 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature is 220°C, the carbonization time is 10 hours, the heating rate of the pyrolysis activation process is 15°C / min, the activation temperature is 850°C, the activation time is 3 hours, and the nitrogen flow rate is 10 mL / min.

[0082] The specific surface area of ​​the activated carbon prepared is 1123.5m 2 / g, the average pore size is 1.66nm, and the proportion of micropores is 96%.

[0083] Example 6

[0084] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0085] Weigh 8.7 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature is 140°C, the carbonization time is 16 hours, the heating rate of the pyrolysis activation process is 15°C / min, the activation temperature is 1000°C, the activation time is 0.5 hours, and the nitrogen flow rate is 50 mL / min.

[0086] The specific surface area of ​​the prepared activated carbon is 913.21 m 2 / g, the average pore size is 2.19nm, and micropores account for 77%.

[0087] Example 7

[0088] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0089] Weigh 12 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature is 180°C, the carbonization time is 16 hours, the heating rate of the pyrolysis activation process is 5°C / min, the activation temperature is 800°C, the activation time is 1 hour, and the nitrogen flow rate is 200 mL / min.

[0090] The specific surface area of ​​the prepared activated carbon is 440.1 m 2 / g, the average pore size is 2.07nm, and the proportion of micropores is 92%.

[0091] Example 8

[0092] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0093] Weigh 7.4 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature is 140°C, the carbonization time is 4 hours, the heating rate of the pyrolysis activation process is 15°C / min, the activation temperature is 700°C, the activation time is 3 hours, and the nitrogen flow rate is 200 mL / min.

[0094] The specific surface area of ​​the activated carbon prepared is 330.6 m 2 / g, the average pore size is 1.79nm, and the proportion of micropores is 68%.

[0095] Example 9

[0096] This embodiment provides a method for preparing biomass activated carbon, wherein the amount of raw materials, the parameters of the hydrothermal carbonization step and the parameters of the activation step are as follows, and the processing methods of other raw materials, intermediates and products are the same as those in Example 1:

[0097] Weigh 8.1 g of washed and air-dried bamboo blocks, the hydrothermal carbonization temperature is 140°C, the carbonization time is 4 hours, the heating rate of the pyrolysis activation process is 5°C / min, the activation temperature is 1000°C, the activation time is 0.5 hours, and the nitrogen flow rate is 200 mL / min.

[0098] The specific surface area of ​​the prepared activated carbon is 181.5 m 2 / g, the average pore size is 1.82nm, and micropores account for 78%.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing biomass activated carbon, which is different from Example 1 in that step 1 is different, and specifically comprises the following steps:

[0101] Step 1, immersing 6.2 g of a single bamboo block after washing and air-drying in a 50 wt.% phosphoric acid aqueous solution, reacting at room temperature of 25° C. for 24 hours, and then drying the immersed bamboo block;

[0102] Step 2: Place the dried bamboo block in a tubular furnace, introduce nitrogen at a flow rate of 10 mL / min, heat to 1000°C at a heating rate of 15°C / min, and activate at this temperature for 0.5 hours. After activation, start cooling, and continue to introduce nitrogen during the process. When the furnace temperature drops to 50°C, take out the activated carbon sample.

[0103] Step 3: Wash the activated carbon with clean water to remove water-soluble impurities such as soluble salts or incompletely reacted residues. The washed activated carbon is dried in an oven at 105°C to a constant weight, and after the sample is cooled to room temperature, it is weighed and stored to obtain an activated carbon sample.

[0104] The specific surface area of ​​the activated carbon prepared is 797.2 m 2 / g, the average pore size is 2.3nm, and micropores account for 72%.

[0105] Comparative Example 2

[0106] This comparative example provides a method for preparing biomass activated carbon, which specifically comprises the following steps:

[0107] Step 1, drying 4.6 g of a single bamboo block after washing and air-drying;

[0108] Step 2: Place the dried bamboo block in a tubular furnace, introduce nitrogen at a flow rate of 10 mL / min, heat to 1000°C at a heating rate of 15°C / min, introduce water vapor at a flow rate of 5 ml / min, and activate at this temperature for 0.5 hours. After activation, start cooling, and continue to introduce nitrogen during the process. When the furnace temperature drops to 50°C, take out the activated carbon sample.

[0109] Step 3: Wash the activated carbon with clean water to remove water-soluble impurities such as soluble salts or incompletely reacted residues. The washed activated carbon is dried in an oven at 105°C to a constant weight, and after the sample is cooled to room temperature, it is weighed and stored to obtain an activated carbon sample.

[0110] The specific surface area of ​​the activated carbon prepared is 613.4 m 2 / g, the average pore size is 2.5nm, and the proportion of micropores is 64%.

[0111] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing biomass activated carbon, characterized in that: include: placing a raw material mixture including a biomass raw material and water in a closed reactor for hydrothermal carbonization reaction to obtain a solid-liquid mixture; The solid phase product in the solid-liquid mixture is separated, and the solid phase product is placed in a protective gas atmosphere to carry out a self-hydrothermal activation reaction 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 is a raw material containing lignocellulose.

3. The method for preparing biomass activated carbon according to claim 1, characterized in that: The hydrothermal carbonization reaction temperature is 140°C to 250°C, and the time is 4h to 24h; Preferably, the hydrothermal carbonization reaction temperature is 140° C. to 220° C., and the time is 10 h to 16 h.

4. The method for preparing biomass activated carbon according to claim 1, characterized in that: In the raw material mixture, water submerges the biomass raw material.

5. The method for preparing biomass activated carbon according to claim 1, characterized in that: The protective gas is an inert gas.

6. The method for preparing biomass activated carbon according to claim 1, characterized in that: During the self-hydrothermolysis activation reaction, a protective gas is introduced into the reactor carrying the solid phase product, and the flow rate of the protective gas is 10 mL / min to 300 mL / min, preferably 10 mL / min to 50 mL / min.

7. The method for preparing biomass activated carbon according to claim 1, characterized in that: The temperature of the self-hydrothermal activation reaction is 500°C to 1100°C, and the time is 0.5h to 4h; Preferably, the temperature of the self-hydrothermolysis activation reaction is 850° C. to 1000° C., and the time is 0.5 h to 3 h.

8. The method for preparing biomass activated carbon according to claim 1, characterized in that: The heating rate of the self-hydrothermolysis activation reaction step is 2°C / min to 20°C / min, preferably 10°C / min to 20°C / min.

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

10. The biomass activated carbon according to claim 9, characterized in that: The biomass activated carbon meets at least one of the following AC characteristics: A. The specific surface area of ​​the biomass activated carbon is 100m 2 / g~3200m 2 / g; B. The average pore size of the biomass activated carbon is 1nm to 2.5nm; C. The micropores of the biomass activated carbon account for 77% to 98%.

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