Device and method for preparing controllable high-specific-surface-area activated carbon based on oxygen-carbon ratio

Abstract

The invention relates to a device and a method for preparing controllable high-specific-surface-area activated carbon based on an oxygen-carbon ratio. The method comprises the following steps: carrying out low-temperature pre-deoxidation on a biomass raw material at 250-400 DEG C; fully mixing the solid-phase product subjected to low-temperature pre-deoxidation with an active agent according to a certain proportion; and heating the mixture to 600-1000 DEG C for activation, separating and recycling the active agent, and drying a solid product to obtain the controllable high-specific-surface-area active carbon based on the oxygen-carbon ratio. In order to solve the problems that a traditional activated carbon preparation method is complex in process, the pore structure of activated carbon is difficult to directionally regulate and control and the like, the oxygen-carbon ratio (O / C) in a carbon precursor is used as a predictive factor of the pore structure of biomass-based porous carbon, a deoxidation carbonization reactor is used for carrying out low-temperature pre-deoxidation on a biomass raw material, and the oxygen-carbon ratio of the carbon precursor is purposefully regulated and controlled, so that the biomass-based porous carbon is prepared. And predictable directional preparation of the pore structure of the biomass-based porous carbon is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of biomass activated carbon, and in particular to a device and method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio. Background Art

[0002] Activated carbon is a porous carbon material with a large specific surface area, which is mainly used in high-value fields such as energy storage, catalysis, environment, medical treatment, and food. Traditional activated carbon preparation processes mostly use non-renewable fossil carbon such as coal as raw materials, and use physical or chemical processes to activate and pore the carbonized products. Among them, the regulation of the pore structure of activated carbon is particularly important, which significantly affects its activity and selectivity in the fields of energy storage, adsorption, catalysis, etc.

[0003] With the excessive dependence of human society on fossil fuels and the increasingly serious energy depletion and global ecological and environmental problems, it is urgent to promote renewable energy substitution. As the only carbon-containing renewable energy, biomass has shown great potential in the preparation of green activated carbon due to its abundant and cheap source and zero carbon and negative carbon properties.

[0004] The preparation of solid activated carbon materials from biomass through pyrolysis-activation process is undoubtedly one of the most promising methods for preparing green activated carbon. Pyrolysis is one of the common technologies for efficient utilization of biomass. By applying thermal energy under an inert atmosphere, the macromolecular compounds in the biomass are broken and decomposed to obtain biochar precursors. After subsequent physical and chemical activation treatments and other refined steps, it can be converted into biomass-based activated carbon materials with a significant porous structure. At present, some biomass-based activated carbon materials have initially achieved commercial application, showing great potential and value.

[0005] However, current research experience mostly comes from coal-based activated carbon, which often focuses on the study of activation process parameters. The pore structure is adjusted by regulating activation parameters such as activation temperature / time / activator type, ignoring the influence of biomass characteristics. As a result, the performance of the prepared activated carbon often varies due to differences in raw materials and precursor preparation methods. The final pore parameters often rely on trial and error experiments, presenting application difficulties such as variable and difficult to predict pore structures. It is difficult to prepare predictable and controllable directional pore structures of biomass-based activated carbon. There is an urgent need for innovation in process methods and equipment to prepare biomass carbon materials with precise and controllable pore size distribution and pore volume that can meet specific application requirements. Summary of the invention

[0006] In view of the above problems, a device and method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio are provided, the technical purpose of which is to achieve predictable directional regulation of the pore structure of biomass-based porous carbon.

[0007] The specific technical solutions are as follows:

[0008] The first aspect of the present invention is to provide a method for preparing activated carbon with a controllable high specific surface area based on oxygen-carbon ratio, characterized in that it comprises:

[0009] The biomass raw material is pre-deoxygenated at low temperature of 250-400°C;

[0010] The solid phase product after low-temperature pre-deoxidation is fully mixed with the active agent in a certain proportion;

[0011] The mixture is heated to 600-1000°C for activation, the activating agent is separated and recycled, and the solid product is dried to obtain a controllable high specific surface area activated carbon based on the oxygen-carbon ratio.

[0012] Furthermore, the mass ratio of the activator to the solid phase product is 1:4-1:1.

[0013] Furthermore, the activator is one of an alkaline salt or a strong base.

[0014] Furthermore, the biomass raw material is agricultural and forestry waste with lignocellulose as the main component.

[0015] The second aspect of the present invention is to provide a device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio, comprising:

[0016] A feed module, used for storing and providing biomass raw materials;

[0017] The thermal deoxygenation module is used to receive the feed from the feed module and perform low-temperature pre-deoxygenation on the biomass raw materials.

[0018] The activation module is used to receive the feed from the thermal deoxidation module, and mix the solid phase product after low-temperature pre-deoxidation with the activator and then heat and keep it warm;

[0019] The post-processing module is used to receive the feed from the activation module and separate and reuse the active agent and useful substances;

[0020] The heating module is used to receive the feed from the thermal deoxidation module, the activation module and the post-processing module, and use the generated heat to heat the corresponding modules.

[0021] Furthermore, the feeding module includes a biomass silo and a feeder, and the biomass silo is connected to the feeder.

[0022] Furthermore, the thermal deoxygenation module is composed of a deoxygenation reactor, and the deoxygenation reactor is connected to the feeder.

[0023] Furthermore, the activation module includes a material mixing bin, an activation reactor, and an activator storage bin; the deoxygenation reactor, the material mixing bin, and the activator storage bin are connected in sequence, and the activator storage bin is connected to the material mixing bin.

[0024] Furthermore, the post-processing module includes a primary sealed tank, a secondary sealed tank, a tertiary sealed tank, a filter press, an activated carbon drying bin, an activated carbon storage bin, and an alkali solution recovery tank; the activation reactor, the primary sealed tank, the secondary sealed tank, the tertiary sealed tank, the filter press, and the activated carbon drying bin are connected in sequence, the activated carbon drying bin is connected with the activated carbon storage bin and the alkali solution recovery tank respectively, and the alkali solution recovery tank is connected with the primary sealed tank.

[0025] Furthermore, the heating module includes a low-temperature combustion chamber, a thermal oil tank, and an exhaust gas treatment device. The low-temperature combustion chamber is connected to the activation reactor and the first-level sealed tank. The heat generated by the low-temperature combustion chamber is supplied to the deoxygenation reactor via the thermal oil tank, and the remaining heat is supplied to the activated carbon drying chamber, the alkali solution recovery tank, the first-level sealed tank, the second-level sealed tank, and the third-level sealed tank in sequence.

[0026] The beneficial effects of the above scheme are:

[0027] 1) In view of the problems that the traditional activated carbon preparation method is complex and the pore structure of activated carbon is difficult to be directional controlled, the present invention uses the oxygen-carbon ratio (O / C) in the carbon precursor as a predictive factor for the pore structure of biomass-based porous carbon, uses a deoxygenation carbonization reactor to pre-deoxygenate the biomass raw material at low temperature, and achieves predictable directional preparation of the pore structure of biomass-based porous carbon by purposefully controlling the oxygen-carbon ratio of the carbon precursor;

[0028] 2) In view of the problem that the high-temperature pyrolysis oil and gas produced by the activation furnace is easily mixed with trace amounts of activators and the traditional high-temperature combustion process is prone to corrosion and damage to the furnace body, the present invention innovatively introduces a low-temperature combustion chamber, and passes the low-temperature pyrolysis oil and gas produced by the activation reactor and the high-temperature pyrolysis oil and gas into the low-temperature combustion chamber for controllable low-temperature combustion. While ensuring the energy efficiency of the system, the problem of easy corrosion and damage of the traditional high-temperature combustion chamber is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of a preparation device provided in an embodiment of the present invention;

[0030] Figure 2 It is a schematic structural diagram of a deoxygenation reactor provided in an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the structure of a material mixing bin provided in an embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of the structure of an activation reactor provided in an embodiment of the present invention;

[0033] Figure 5 It is a schematic diagram of the structure of a sealed can provided in an embodiment of the present invention;

[0034] Figure 6This is a test diagram of the pore structure and specific surface area of ​​the activated carbon provided in the embodiments of the present invention.

[0035] In the attached drawings: 1, biomass silo; 2, feeder; 3, deoxygenation reactor; 3-1, reactor inlet; 3-2, feed screw; 3-3, reactor insulation interlayer; 3-4, motor; 3-5, gas outlet; 3-6, solid outlet; 4, material mixing silo; 4-1, mixing silo inlet; 4-2, shell; 4-3, stirrer; 4-4, motor; 4-5, activator inlet; 4-6, solid outlet; 5, activation reactor; 5-1, reactor inlet; 5-2, insulation interlayer; 5-3, microwave generator; 5- 4. Electric heater; 5-5. Motor; 5-6. Agitator; 5-7. Gas outlet; 5-8. Solid outlet; 6. Alkaline agent storage bin; 7. Primary sealed tank; 7-1. Tank inlet; 7-2. Liquid inlet; 7-3. Liquid outlet; 7-4. Gas outlet; 7-5. Tank outlet; 8. Secondary sealed tank; 9. Tertiary sealed tank; 10. Filter press; 11. Activated carbon drying bin; 12. Activated carbon storage bin; 13. Alkali solution recovery pool; 14. Low-temperature combustion chamber; 15. Thermal oil tank; 16. Exhaust gas treatment device. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0038] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0039] The invention provides a method for preparing activated carbon with a controllable high specific surface area based on an oxygen-carbon ratio, comprising: pre-deoxidizing a biomass raw material (the biomass raw material is agricultural and forestry waste mainly composed of lignocellulose) at a low temperature of 250-400°C; fully mixing a solid phase product after the low temperature pre-deoxidation with an activator (the activator is one of alkaline salts or strong bases, including but not limited to one or more of KOH, NaOH, K2CO3, and NaCO3) at a mass ratio of 1:4-1:1; heating the mixture to 600-1000°C for activation, separating and recycling the activator, and drying the solid product to obtain activated carbon with a controllable high specific surface area based on an oxygen-carbon ratio.

[0040] Using the above method, such as Figure 1 As shown, in an embodiment of the present invention, a device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio is provided, which includes a feeding module, a thermal deoxygenation module, an activation module, a post-processing module, and a heating module; the feeding module is used to store and provide biomass raw materials; the thermal deoxygenation module is used to receive feeding from the feeding module, and perform low-temperature pre-deoxygenation on the biomass raw materials; the activation module is used to receive feeding from the thermal deoxygenation module, and mix the solid phase product after low-temperature pre-deoxygenation with the activating agent, and then heat and keep it warm; the post-processing module is used to receive feeding from the activation module, and separate and reuse the activating agent and useful substances; the heating module is used to receive feeding from the thermal deoxygenation module, the activation module and the post-processing module, and use the generated heat to heat the corresponding modules.

[0041] A group is a specific example, such as Figure 1 As shown, the feeding module includes a biomass silo 1 and a feeder 2 , and the biomass silo 1 is communicated with the feeder 2 so as to supply materials to subsequent modules through the feeder 2 .

[0042] A group is a specific example, such as Figure 1 , Figure 2 As shown, the thermal deoxygenation module is composed of a deoxygenation reactor 3. The deoxygenation reactor is composed of a reactor inlet 3-1, a feed screw 3-2, a reactor insulation interlayer 3-3, a motor 3-4, a gas outlet 3-5, and a solid outlet 3-6. The deoxygenation reactor 3 is used for low-temperature pre-deoxygenation of biomass raw materials, and is provided with a feed screw 3-2 inside, which is driven by a motor 3-4. The cavity of the reactor insulation interlayer 3-3 is connected to the thermal oil tank 15, and thermal oil is introduced to provide a constant temperature environment required for pre-deoxygenation; the combustible gas generated during the reaction is input into the low-temperature combustion chamber 14 through the gas outlet 3-5.

[0043] A group is a specific example, such as Figure 1 , Figure 3 , Figure 4 As shown, the activation module includes a material mixing bin 4, an activation reactor 5, and an alkaline agent storage bin 6. Figure 3 As shown, the material mixing bin 4 is composed of a mixing bin inlet 4-1, a shell 4-2, a stirrer 4-3, a motor 4-4, an activator inlet 4-5 and a solid outlet 4-6. The mixing bin inlet 4-1 is connected to the solid outlet 3-6 of the deoxygenation reactor for inputting the pre-deoxygenated material; the activator inlet 4-5 is connected to the alkaline agent storage bin 6 for inputting the activator; the two are fully stirred and mixed by the stirrer 4-3 in the shell 4-2 to form a mixed material, which is input into the activation reactor 5 through the solid outlet 4-6. Figure 4As shown, the activation reactor 5 is composed of a reactor inlet 5-1, a heat-insulating interlayer 5-2, a microwave generator 5-3, an electric heater 5-4, a motor 5-5, an agitator 5-6, a gas outlet 5-7 and a solid outlet 5-8. The reactor inlet 5-1 is connected to the solid outlet 4-6 of the material mixing bin, and the mixed material is input; the activation reactor 5 is provided with an electric heater 5-4 inside, a microwave generator 5-3 in the interlayer, and a heat-insulating layer 5-2 outside. When working, the motor 5-5 drives the agitator 5-6 to stir the reaction material. Under the simultaneous heating of the electric heat and microwave inside and outside, the reaction is more uniform. The reacted material is discharged to the three-stage sealed tank 9 through the solid outlet 5-8, and the flammable gas generated during the reaction is input to the low-temperature combustion chamber 14 through the gas outlet 5-7.

[0044] A group is a specific example, such as Figure 1 , Figure 5 As shown, the post-processing module includes a primary sealed tank 7, a secondary sealed tank 8, a tertiary sealed tank 9, a filter press 10, an activated carbon drying bin 11, an activated carbon storage bin 12 and an alkali solution recovery tank 13. Figure 5 As shown, the first-level sealed tank 7 consists of a tank body inlet 7-1, a liquid inlet 7-2, a liquid outlet 7-3, a solid outlet 7-4, a gas outlet 7-5 and a tank body outlet 7-6; the second-level sealed tank 8 and the third-level sealed tank 9 have no gas outlet, and the rest of the structure is the same as the first-level sealed tank 7. The tank inlet 7-1 is connected to the solid outlet 5-8 of the activation reactor for inputting hot reacted materials; the liquid inlet 7-2 is connected to the liquid outlet of the secondary sealed tank for inputting cleaning liquid; the solid outlet 7-4 is connected to the solid inlet of the secondary sealed tank for secondary cleaning of the reacted materials; the combustible oil gas that may be generated due to the high temperature in the cleaning process is input to the low-temperature combustion chamber 14 via the gas outlet 7-5; the waste liquid is transported to the alkali solution recovery pool 13 via the liquid outlet 7-3; the solid product is cleaned in turn by the primary sealed tank 7, the secondary sealed tank 8, and the tertiary sealed tank 9, enters the filter press 10, and after physically squeezing out most of the cleaning liquid, enters the activated carbon drying bin 11 for drying to remove the remaining moisture, and is temporarily stored in the activated carbon storage bin 12; the water used for cleaning is provided by the side water inlet of the tertiary sealed tank 9, and the liquid after cleaning the tertiary sealed tank 9 is used as the cleaning liquid of the secondary sealed tank 8, and the liquid after cleaning the secondary sealed tank 8 is used as the cleaning liquid of the primary sealed tank 7, and finally enters the alkali solution recovery pool 13 to evaporate and recover the alkaline agent.

[0045] A group is a specific example, such as Figure 1 , Figure 5 As shown, the heating module is composed of a low-temperature combustion chamber 14, a thermal oil tank 15, and an exhaust gas treatment device 16. The low-temperature combustion chamber 14 first provides heat to the thermal oil tank 15, and the generated hot flue gas flows through the activated carbon drying bin 11, the alkali solution recovery tank 13, the first-level sealed tank 7, the second-level sealed tank 8, and the third-level sealed tank 9 in sequence, and is discharged after passing through the exhaust gas treatment device 16.

[0046] The working method of the above-mentioned device in the present invention is:

[0047] During the startup phase of the device, the raw materials in the biomass silo 1 enter the deoxygenation reactor 3 through the feeder 2. Through low-temperature deoxygenation pretreatment, the moisture and some volatile organic matter in the biomass are removed, and the oxygen content of the raw materials is adjusted. The deoxygenation reactor 3 is heated by the thermal oil tank 15, and the temperature is controlled at 250-400°C; the solid product after low-temperature deoxygenation pretreatment enters the material mixing bin 4, and is fully mixed with the activator in a mass ratio of 1:4-1:1 and enters the activation reactor 5, and is activated at a high temperature of 600-1000°C. The activated product obtained is cleaned by the first-level sealed tank 7, the second-level sealed tank 8, and the third-level sealed tank 9 to remove the alkaline residue, and then squeezed in the filter press 10 to remove most of the moisture, and then dried in the activated carbon drying bin 11. The activated carbon finally obtained is stored in the activated carbon storage bin 12.

[0048] The oil and gas products produced by the deoxygenation reactor 3, the activation reactor 5 and the first-level sealed tank 7 enter the low-temperature combustion chamber 14 for low-temperature combustion. The heat generated is preferentially supplied to the deoxygenation reactor 3 through the thermal oil tank 15, and the remaining heat in the tail gas is sequentially supplied to the activated carbon drying bin 11, the alkali solution recovery tank 13, the first-level sealed tank 7, the second-level sealed tank 8, and the third-level sealed tank 9, thereby realizing the heat recovery and self-heating of the system. The insufficient part can be supplied by external fuel, which can effectively reduce the system and improve the system efficiency.

[0049] By using the above device, a series of biomass charcoals are prepared in the present invention, and the pore structure and specific surface area thereof are as follows: Figure 6 As shown. Figure 6 It can be seen that the specific surface area and pore structure of biochar prepared after activation of carbon precursors with different oxygen contents show regular changes with the oxygen content of the carbon precursor, and the specific surface area of ​​activated carbon also has an optimal value range.

[0050] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio, characterized in that: include: The biomass raw materials are pre-deoxidized at a low temperature of 250-400°C; The solid phase product after low-temperature pre-deoxidation is fully mixed with the active agent in a certain proportion; The mixture is heated to 600-1000°C for activation, the active agent is separated and recycled, and the solid product is dried to obtain a controllable high specific surface area activated carbon based on the oxygen-carbon ratio.

2. The method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 1, characterized in that: The mass ratio of the activator to the solid phase product is 1:4-1:

1.

3. The method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 2, characterized in that: The activator is one of an alkaline salt or a strong base.

4. The method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 1, characterized in that: The biomass raw material is agricultural and forestry waste with lignocellulose as the main component.

5. A device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio, characterized in that: The method for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to any one of claims 1 to 4 comprises: A feeding module, used for storing and providing biomass raw materials; The thermal deoxygenation module is used to receive the feed from the feed module and perform low-temperature pre-deoxygenation on the biomass raw materials. An activation module is used to receive the feed from the thermal deoxidation module, mix the solid phase product after low-temperature pre-deoxidation with an activator, and then heat and keep it warm; A post-processing module, configured to receive feed from the activation module and separate and reuse the active agent and useful substances; The heat supply module is used to receive feeds from the thermal deoxidation module, the activation module and the post-processing module, and use the generated heat to heat the corresponding modules.

6. The device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 5, characterized in that: The feeding module includes a biomass silo and a feeder, and the biomass silo is communicated with the feeder.

7. The device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 6, characterized in that: The thermal deoxidation module consists of a deoxidation reactor, which is communicated with the feeder.

8. The device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 7, characterized in that: The activation module includes a material mixing bin, an activation reactor, and an active agent storage bin; the deoxidation reactor, the material mixing bin, and the active agent storage bin are sequentially connected, and the active agent storage bin is connected to the material mixing bin.

9. The device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 8, characterized in that: The post-processing module includes a primary sealed tank, a secondary sealed tank, a tertiary sealed tank, a filter press, an activated carbon drying bin, an activated carbon storage bin, and an alkali solution recovery tank; the activation reactor, the primary sealed tank, the secondary sealed tank, the tertiary sealed tank, the filter press, and the activated carbon drying bin are connected in sequence, the activated carbon drying bin is connected with the activated carbon storage bin and the alkali solution recovery tank respectively, and the alkali solution recovery tank is connected with the primary sealed tank.

10. The device for preparing activated carbon with controllable high specific surface area based on oxygen-carbon ratio according to claim 9, characterized in that: The heating module includes a low-temperature combustion chamber, a thermal oil tank, and an exhaust gas treatment device. The low-temperature combustion chamber is connected to the activation reactor and the first-level sealed tank. The heat generated by the low-temperature combustion chamber is supplied to the deoxidation reactor through the thermal oil tank, and the remaining heat is supplied to the activated carbon drying chamber, the alkali solution recovery tank, the first-level sealed tank, the second-level sealed tank, and the third-level sealed tank in sequence.

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