Rigid-loose capacitor carbon and preparation method and application thereof

Abstract

The invention discloses rigid pine capacitance carbon and a preparation method and application thereof. The method comprises the following steps that bark of rigid pine is removed, then the rigid pine is smashed into wood chips of 20-40 meshes, an alkaline solution is added into the wood chips, reaction treatment is conducted, then solid-liquid separation, washing and drying are conducted on a reaction product, and pretreated rigid pine particles are obtained; putting the pretreated rigid pine particles into a fluidized bed reactor, introducing gas for activation, and spraying an auxiliary agent at the same time, so as to obtain rigid pine porous carbon; cooling gas N2 is added into the fluidized bed reactor to reduce the temperature in the reactor, and the just loose porous carbon is separated and collected after cooling; and further grinding the collected rigid loose porous carbon into fine powder, and screening to obtain capacitor carbon particles with proper particle sizes. According to the invention, biomass rigid pine with high lignocellulose content is selected as a raw material, cellulose and hemicellulose in lignocellulose are helpful for forming more pores, and lignin is helpful for synthesizing graphitized carbon, so that the conductivity is improved.

Description

Technical Field

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

[0002] With the increase in fossil fuel consumption and the decrease in reserves, energy sustainability has become a major factor worldwide. Driven by environmental and usage needs, it is particularly important to develop environmentally friendly and cheap renewable energy systems, such as wind power, solar energy, fuel cells and tidal energy. However, the continuous supply of intermittent energy from these systems requires an efficient and practical storage system to ensure safe and continuous power collection. Supercapacitors have attracted widespread attention due to their long cycle life, fast charge and discharge rates, high power density, and adaptability to harsh environmental conditions. However, supercapacitors are not without disadvantages. The only disadvantage is the low energy density. Therefore, the development of an advanced porous carbon electrode material has become a top priority in supercapacitor research.

[0003] As a rich and renewable natural resource, wood has gradually become a hot spot for the research and application of capacitor carbon in recent years. Compared with traditional coal or coconut shells, wood is cheaper, more abundant and sustainable. Its unique organic structure makes wood capacitor carbon have good potential in terms of pore structure and specific surface area. In addition, the raw material processing process of wood capacitor carbon is simple and environmentally friendly, so it has a great market application prospect.

[0004] Pine has unique advantages as capacitor carbon. The density of pine wood is low, usually 0.4-0.6g / cm 3 This makes it lighter than other woods such as oak and walnut. The lower density means that it is easier to generate carbon materials with a larger specific surface area when making capacitor carbon. Compared with some other pine species, the resin content of pine wood is lower. Resin may produce unstable by-products during the carbonization process, affecting the electrochemical properties of the final carbon material. The lower resin content of pine makes its carbonization process smoother, which helps to obtain capacitor carbon with higher purity and better electrical properties. Moreover, the pore structure in pine wood is natural and relatively regular, which helps the capacitor carbon retain certain micropores and mesopores during the preparation process. These pore structures can improve its charge storage capacity.

[0005] At present, the preparation methods of traditional capacitor carbon mainly include physical activation method, chemical activation method and direct carbonization method. These methods generally use natural organic materials such as coal, coconut shell, wood as raw materials, and achieve carbonization and activation through high temperature treatment and specific chemical reactions. However, these preparation methods often have the following problems: high energy consumption, the traditional carbonization and activation process usually needs to be carried out at high temperature and takes a long time to complete. High energy consumption not only increases production costs, but also puts great pressure on the environment; uneven reaction, some traditional methods (such as tubular furnace carbonization, activation, etc.) often have problems such as uneven heat conduction and unstable reaction process, resulting in uneven product quality and difficult to control pore structure; low resource utilization, wood and other raw materials in traditional preparation methods usually need to go through a long carbonization and activation process, and the quality and structure of the carbonized product may not be fully suitable for the needs of high-performance capacitors, resulting in low utilization efficiency of resources such as wood; environmental protection issues, some traditional preparation methods (such as chemical activation method) will release toxic gases and harmful wastes during the production process, causing environmental pollution.

[0006] Therefore, how to improve the production efficiency of capacitor carbon, reduce energy consumption, improve its electrochemical properties, and maximize the utilization of resources has become a research hotspot in current capacitor carbon preparation technology. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a Gangsong capacitor carbon and a preparation method and application thereof, so as to solve the current technical problems of low production efficiency, high energy consumption and poor electrochemical performance of capacitor carbon.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] The present invention provides a method for preparing a carbon nanotube capacitor, comprising the following steps:

[0010] S1. Pretreatment of pine wood: removing the bark from the pine wood, and then crushing it into sawdust of 20-40 mesh, adding an alkaline solution to the sawdust, reacting it, and then performing solid-liquid separation, washing and drying the reaction product to obtain pretreated pine particles;

[0011] S2, activation: placing the pretreated pine particles into a fluidized bed reactor, introducing gas for activation, and spraying an additive to obtain pine porous carbon;

[0012] S3, separation and collection: adding cooling gas N2 to the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0013] S4. Grinding and screening: The collected porous carbon is further ground into fine powder and screened to obtain capacitor carbon particles of suitable particle size.

[0014] As a new type of reactor technology, the fluidized bed reactor has high efficiency and uniform heat conduction and material mixing capabilities, so it is widely used in many high-temperature reactions and gas-solid reactions. The fluidized bed reactor suspends solid particles through high-speed airflow, making the particles behave like fluids in the reactor. This "fluidized" state can achieve rapid heating and uniform reaction of materials, thereby greatly improving the reaction efficiency.

[0015] Advantages of ebullating bed reactors include:

[0016] Uniform heating and efficient reaction: The particles in the fluidized bed can be evenly distributed and move continuously with the airflow, so that the temperature and atmosphere conditions inside the reactor remain stable, thereby achieving uniform heating and effective activation of the materials. This helps to improve the pore structure and electrochemical performance of wood capacitor carbon.

[0017] Shorter reaction time: Since the fluidized bed reactor has good heat conduction performance, the raw materials can reach the required reaction temperature in a shorter time, reducing the reaction time and energy consumption.

[0018] Efficient gas-solid contact: The design of the fluidized bed reactor allows for more complete contact between the gas and solid particles, which helps improve the reaction efficiency between the reactants in the gas and the solid raw materials, and improves the quality and performance of the capacitor carbon.

[0019] Environmental protection: The fluidized bed reactor can avoid the generation of harmful gases by precisely controlling the atmosphere (such as using inert gases or activated gases such as nitrogen and carbon dioxide). At the same time, the waste gas generated during the reaction can also be effectively treated by a gas recovery device to reduce environmental pollution.

[0020] Strong adaptability to raw materials: The fluidized bed technology can process a variety of raw materials, including wood, plant fiber, agricultural waste, etc., and has good adaptability to raw materials. Especially when processing biomass raw materials such as wood, it can better retain the natural structure of the raw materials and improve the specific surface area and electrochemical properties of carbon.

[0021] Therefore, using an ebullating bed reactor for wood carbonization can produce high-quality wood capacitor carbon in a short time, with low energy consumption and high resource utilization. Using an ebullating bed reactor to prepare wood capacitor carbon has great technical advantages. It can not only improve the preparation efficiency of capacitor carbon and improve its performance, but also make full use of biomass resources such as wood to promote green and sustainable development.

[0022] Preferably, in step S1, the drying is forced air drying, the drying temperature is 80-100°C, the drying is slowly heated drying, and the heating rate is 5-10°C / min.

[0023] Preferably, in step S1, the alkaline solution is a sodium carbonate solution or a potassium carbonate solution, and the mass concentration of the alkaline solution is 10% to 15%.

[0024] Preferably, in step S2, the auxiliary agent is a mixed solution of cupric chloride and lead nitrate, the mass concentration of the cupric chloride solution is 10-20%, and the mass concentration of the lead nitrate solution is 5-10%.

[0025] Preferably, in step S2, the activation time is 2 to 6 hours, and the activation temperature is 800 to 900°C.

[0026] Preferably, in step S2, the gas is at least one of CO2 and water vapor, and the flow rate of the gas is 0.2-1.5 m / s. Under these gas atmospheres, the carbon fiber can complete the activation pore-forming process to obtain a porous carbon material with a high specific surface area.

[0027] When the gas is a mixture of CO2 and water vapor, the volume ratio of CO2 to water vapor is 1:1.

[0028] Preferably, in step S3, a cyclone separator is used to separate and collect the rigid pine porous carbon.

[0029] Preferably, in step S4, the particle size of the capacitor carbon particles is 6-8 μm.

[0030] The present invention also provides a pine capacitor carbon, which is prepared by the preparation method of the pine capacitor carbon as described above.

[0031] The present invention further proposes an application of the pine capacitor carbon for use as a supercapacitor electrode material.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention selects pine, a biomass with a high content of lignocellulose, as a raw material. The cellulose and hemicellulose in the lignocellulose help to form more pores, while the lignin helps to synthesize graphitized carbon to improve conductivity.

[0034] (2) The present invention selects an ebullated bed as a reactor. Compared with the traditional tubular reactor, it has the advantages of high heat and mass transfer efficiency, uniform bed temperature, and reduced energy consumption, which helps to improve the pore structure and electrochemical properties of Gangsong capacitor carbon. The fluid mechanics environment and physical activation process of the ebullated bed reactor cooperate with each other to more accurately control the formation and development of the pore structure of the carbon material. By adjusting the operating parameters of the reactor, such as temperature, gas flow rate, residence time, etc., the proportion and pore size of micropores, mesopores, etc. of the carbon material can be regulated to meet the requirements of supercapacitors for electrode materials.

[0035] (3) The preparation method of the pine capacitor carbon provided by the present invention is simple and easy to operate. The biomass pine raw material is first crushed, and then an alkaline solution is added and pretreated with a slow heating and drying process to keep the pores and channel structures in the pine particles intact. Subsequently, high-temperature gas is introduced for activation, and a mixed solution of activation aids copper chloride and lead nitrate is sprayed. The aids can be converted into copper oxide and lead oxide at high temperatures, which can support the carbon skeleton to form pores and prevent its shrinkage and collapse during the high-temperature activation and carbonization process. When used as a supercapacitor electrode material, the lead oxide can undergo a reversible redox reaction to store energy, thereby increasing the total capacitance of the pine capacitor carbon. Finally, through separation, collection, grinding and screening operations, capacitor carbon with a large specific surface area and excellent electrical properties can be prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The present invention provides a schematic flow chart of the method for preparing the Gangsong capacitor carbon. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0038] It should be noted that, unless otherwise specified, the chemical reagents involved in the present invention were purchased through commercial channels.

[0039] Example 1

[0040] A method for preparing a pine capacitor carbon comprises the following steps:

[0041] (1) removing the bark from pine wood, and then crushing it into 30-mesh sawdust, adding a sodium carbonate solution to the sawdust, reacting it, and then performing solid-liquid separation and washing on the reaction product, heating it to 90° C. at a rate of 6° C. / min and drying it to obtain pretreated pine particles;

[0042] (2) The pretreated pine particles were placed in a fluidized bed reactor, and CO2 gas was introduced for activation. A mixed solution of copper chloride and lead nitrate was sprayed at the same time. The mass concentration of the copper chloride solution was 10%, and the mass concentration of the lead nitrate solution was 20%. The gas flow rate was controlled at 2m 3 / min, make the raw materials in the bed layer in a boiling state and then mix them for 2 hours, turn on the gas heating switch after mixing evenly, make the inlet hot air temperature 850℃, keep the bed layer in a boiling state for 6 hours, and obtain rigid loose porous carbon;

[0043] (3) adding cooling gas N2 into the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0044] (4) The collected porous carbon is further ground into fine powder and sieved to obtain capacitor carbon particles with a particle size of 7 μm.

[0045] Example 2

[0046] A method for preparing a pine capacitor carbon comprises the following steps:

[0047] (1) removing the bark from pine wood, and then crushing it into 20-mesh sawdust, adding potassium carbonate solution to the sawdust, reacting it, and then performing solid-liquid separation and washing on the reaction product, heating it to 80° C. at a rate of 5° C. / min and drying it, to obtain pretreated pine particles;

[0048] (2) The pretreated pine particles were placed in a fluidized bed reactor, and water vapor was introduced for activation. A mixed solution of copper chloride and lead nitrate was sprayed at the same time. The mass concentration of the copper chloride solution was 15%, and the mass concentration of the lead nitrate solution was 8%. The gas flow rate was controlled at 2m 3 / min, make the raw materials in the bed layer in a boiling state and then mix them for 2 hours, turn on the gas heating switch after mixing evenly, make the inlet hot air temperature 800℃, keep the bed layer in a boiling state for 6 hours, and obtain rigid loose porous carbon;

[0049] (3) adding cooling gas N2 into the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0050] (4) The collected porous carbon is further ground into fine powder and sieved to obtain capacitor carbon particles with a particle size of 7 μm.

[0051] Example 3

[0052] A method for preparing a pine capacitor carbon comprises the following steps:

[0053] (1) removing the bark from pine wood, and then crushing it into 40 mesh sawdust, adding sodium carbonate solution to the sawdust, reacting it, and then performing solid-liquid separation and washing on the reaction product, heating it to 100° C. at a rate of 10° C. / min and drying it, to obtain pretreated pine particles;

[0054] (2) The pretreated pine particles were placed in a fluidized bed reactor, and a mixture of CO2 and water vapor with a volume ratio of 1:1 was introduced for activation. At the same time, a mixed solution of copper chloride and lead nitrate was sprayed, with a mass concentration of 20% for the copper chloride solution and 10% for the lead nitrate solution. The gas flow rate was controlled at 2m 3 / min, make the raw materials in the bed layer in a boiling state and then mix them for 2 hours, turn on the gas heating switch after mixing evenly, make the inlet hot air temperature 900℃, keep the bed layer in a boiling state for 6 hours, and obtain rigid loose porous carbon;

[0055] (3) adding cooling gas N2 into the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0056] (4) The collected porous carbon is further ground into fine powder and sieved to obtain capacitor carbon particles with a particle size of 7 μm.

[0057] Comparative Example 1

[0058] A method for preparing a pine capacitor carbon comprises the following steps:

[0059] (1) removing the bark from pine wood, and then crushing it into 30-mesh sawdust, adding a sodium carbonate solution to the sawdust, reacting it, and then performing solid-liquid separation and washing on the reaction product, heating it to 90° C. at a rate of 6° C. / min and drying it to obtain pretreated pine particles;

[0060] (2) The pretreated pine particles were placed in a fluidized bed reactor, and air was introduced. A mixed solution of copper chloride and lead nitrate was sprayed at the same time. The mass concentration of the copper chloride solution was 15%, and the mass concentration of the lead nitrate solution was 8%. The gas flow rate was controlled at 2m 3 / min, make the raw materials in the bed layer in a boiling state and then mix them for 2 hours, turn on the gas heating switch after mixing evenly, make the inlet hot air temperature 850℃, keep the bed layer in a boiling state for 6 hours, and obtain rigid loose porous carbon;

[0061] (3) adding cooling gas N2 into the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0062] (4) The collected porous carbon is further ground into fine powder and sieved to obtain capacitor carbon particles with a particle size of 7 μm.

[0063] Compared with Example 1, the gas introduced in step (2) is air.

[0064] Comparative Example 2

[0065] A method for preparing a pine capacitor carbon comprises the following steps:

[0066] (1) removing the bark from pine wood, crushing it into 30-mesh sawdust, performing solid-liquid separation, washing, heating to 90° C. at a rate of 6° C. / min and drying, thereby obtaining pretreated pine particles;

[0067] (2) The pretreated pine particles were placed in a fluidized bed reactor, and CO2 gas was introduced for activation. A mixed solution of copper chloride and lead nitrate was sprayed at the same time. The mass concentration of the copper chloride solution was 15%, and the mass concentration of the lead nitrate solution was 8%. The gas flow rate was controlled at 2m 3 / min, make the raw materials in the bed layer in a boiling state and then mix them for 2 hours, turn on the gas heating switch after mixing evenly, make the inlet hot air temperature 850℃, keep the bed layer in a boiling state for 6 hours, and obtain rigid loose porous carbon;

[0068] (3) adding cooling gas N2 into the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0069] (4) The collected porous carbon is further ground into fine powder and sieved to obtain capacitor carbon particles with a particle size of 7 μm.

[0070] Compared with Example 1, in Comparative Example 2, the sawdust in step (1) was not treated by reacting with the alkaline solution.

[0071] Comparative Example 3

[0072] A method for preparing a pine capacitor carbon comprises the following steps:

[0073] (1) removing the bark from pine wood, and then crushing it into 30-mesh sawdust, adding a sodium carbonate solution to the sawdust, reacting it, and then performing solid-liquid separation and washing on the reaction product, heating it to 90° C. at a rate of 6° C. / min and drying it to obtain pretreated pine particles;

[0074] (2) Place the pretreated pine particles into a fluidized bed reactor and introduce CO2 gas for activation. Control the gas flow rate at 2 m 3 / min, make the raw materials in the bed layer in a boiling state and then mix them for 2 hours, turn on the gas heating switch after mixing evenly, make the inlet hot air temperature 850℃, keep the bed layer in a boiling state for 6 hours, and obtain rigid loose porous carbon;

[0075] (3) adding cooling gas N2 into the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling;

[0076] (4) The collected porous carbon is further ground into fine powder and sieved to obtain capacitor carbon particles with a particle size of 7 μm.

[0077] Compared with Example 1, in Comparative Example 3, no spraying aid is included in step (2).

[0078] Test methods and results

[0079] Evaluation of electrochemical performance: The electrochemical tests were carried out on an electrochemical workstation (Wuhan Coster). All tests adopted a three-electrode system. The working electrode preparation process was as follows: the Gangsong capacitor carbon prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was mixed with a conductive agent (acetylene black) and a binder (polytetrafluoroethylene) in a mass ratio of 8:1:1, and an appropriate amount of NMP (N-methylpyrrolidone) was added. Stir for 12 h and apply it on the current collector. The application area was 1 cm 2 With the platinum sheet as the counter electrode, the Hg / HgO electrode as the reference electrode, and the prepared electrode sheet as the working electrode, the six electrodes were immersed in 6M KOH electrolyte for constant current charge-discharge and cyclic voltammetry tests. The results are shown in Table 1 below.

[0080] Table 1 Electrode performance test results

[0081]

[0082] It can be seen from Examples 1 to 3 and Comparative Example 1 that water vapor and carbon mainly generate carbon monoxide (CO) and hydrogen through redox reactions, resulting in the formation of more mesopores and macropores; carbon dioxide and carbon mainly generate carbon monoxide (CO) and carbon dioxide (CO2) through redox reactions, often forming more micropores and mesopore structures; the mixed gas activation of CO2 and H2O combines the advantages of both, and can usually generate materials with different pore size distributions under different reaction conditions. The synergistic effect of the two usually leads to a further increase in the specific surface area and the proportion of micropores, and has higher electrochemical performance. Compared with Comparative Examples 1 to 3, the Gangsong capacitor carbon prepared in Examples 1 to 3 of the present invention is used for working electrodes and has better electrochemical performance.

[0083] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, some modifications and improvements can be made to the present invention. Therefore, any modification or improvement made without departing from the spirit of the present invention belongs to the scope of protection claimed in the present invention.

Claims

1. A method for preparing a pine capacitor carbon, characterized in that: The following steps are involved: S1. Pretreatment of pine wood: removing the bark from the pine wood, and then crushing it into sawdust of 20-40 mesh, adding an alkaline solution to the sawdust, reacting it, and then performing solid-liquid separation, washing and drying the reaction product to obtain pretreated pine particles; S2, activation: placing the pretreated pine particles into a fluidized bed reactor, introducing gas for activation, and spraying an additive to obtain pine porous carbon; S3, separation and collection: adding cooling gas N2 to the fluidized bed reactor to reduce the temperature in the reactor, and separating and collecting the rigid loose porous carbon after cooling; S4. Grinding and screening: The collected porous carbon is further ground into fine powder and screened to obtain capacitor carbon particles of suitable particle size.

2. The method for preparing the Gangsong capacitor carbon according to claim 1, characterized in that: In step S1, the drying is forced air drying, the drying temperature is 80-100°C, the drying is slowly heated drying, and the heating rate is 5-10°C / min.

3. The method for preparing the Gangsong capacitor carbon according to claim 1, characterized in that: In step S1, the alkaline solution is a sodium carbonate solution or a potassium carbonate solution, and the mass concentration of the alkaline solution is 10% to 15%.

4. The method for preparing the Gangsong capacitor carbon according to claim 1, characterized in that: In step S2, the auxiliary agent is a mixed solution of cupric chloride and lead nitrate, the mass concentration of the cupric chloride solution is 10-20%, and the mass concentration of the lead nitrate solution is 5-10%.

5. The method for preparing the Gangsong capacitor carbon according to claim 1, characterized in that: In step S2, the activation time is 2 to 6 hours, and the activation temperature is 800 to 900°C.

6. The method for preparing Gangsong capacitor carbon according to claim 1, characterized in that: In step S2, the gas is at least one of CO2 and water vapor, and the flow rate of the gas is 0.2-1.5 m / s.

7. The method for preparing Gangsong capacitor carbon according to claim 1, characterized in that: In step S3, a cyclone separator is used to separate and collect the porous carbon.

8. The method for preparing Gangsong capacitor carbon according to claim 1, characterized in that: In step S4, the particle size of the capacitor carbon particles is 6-8 μm.

9. A kind of Gangsong capacitor carbon, characterized in that: The carbon is prepared by the method for preparing Gangsong capacitor carbon as described in any one of claims 1 to 8.

10. An application of Gangsong capacitor carbon, characterized in that: Used as supercapacitor electrode materials.

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