CN112788934A - Preparation method of wood fiber-based electromagnetic shielding carbon material - Google Patents

Preparation method of wood fiber-based electromagnetic shielding carbon material Download PDF

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Publication number
CN112788934A
CN112788934A CN202011509002.5A CN202011509002A CN112788934A CN 112788934 A CN112788934 A CN 112788934A CN 202011509002 A CN202011509002 A CN 202011509002A CN 112788934 A CN112788934 A CN 112788934A
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product
wood fiber
temperature
graphitization
electromagnetic shielding
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陈超
蒋剑春
孙康
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Institute of Chemical Industry of Forest Products of CAF
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Institute of Chemical Industry of Forest Products of CAF
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/009—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive fibres, e.g. metal fibres, carbon fibres, metallised textile fibres, electro-conductive mesh, woven, non-woven mat, fleece, cross-linked

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Textile Engineering (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

The invention discloses a preparation method of a wood fiber-based electromagnetic shielding carbon material, which comprises the following steps: placing wood fiber raw material in a closed crucible, carbonizing, and soaking the product in Ni2+Dried for use. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, reacting at a high temperature, and cooling to obtain a final product. Aiming at the problem that the wood fiber raw material is difficult to graphitize by the conventional method, the product with higher graphitization degree is successfully prepared by adopting the Ni catalytic method, has a graphite structure with more than 40 layers, and the required temperature is obviously lower than 2800 ℃ required by the conventional graphitization method. In addition, the metal used as the catalyst exists in a simple substance form, which is beneficial to improving the shielding efficiency and also avoids the risk of secondary pollution caused by concentrated acid washing. The shielding effectiveness of the obtained product to 2-18 GHz electromagnetic waves can exceed 60dB, and the product has a good application prospect.

Description

Preparation method of wood fiber-based electromagnetic shielding carbon material
Technical Field
The invention belongs to the technical field of preparation and application of carbonaceous materials, and mainly relates to a preparation method of a wood fiber-based electromagnetic shielding carbon material.
Background
With the rapid development of the electronic industry, various electronic devices, such as computers and wireless communication devices, are becoming popular. These electronic devices continuously radiate electromagnetic waves of various frequencies, thereby causing electromagnetic pollution following air pollution and water pollution, not only causing interference to various electronic devices and electronic communication, but also causing serious harm to human health. Therefore, shielding against electromagnetic radiation and development of shielding materials are particularly important. Electromagnetic shielding means that electromagnetic waves are absorbed or reflected by a shielding material to cause energy attenuation, so that the purpose of preventing the electromagnetic waves from radiating to a specific direction is achieved.
The electromagnetic shielding performance of the material is positively correlated to the conductivity thereof, and thus, the current electromagnetic shielding materials mainly include materials with conductive performance such as metals, conductive polymers, graphite, graphene and the like. Meanwhile, the more developed the pore structure of the material, the more easily the electromagnetic wave is lost due to multiple reflections inside the material, thereby being beneficial to improving the electromagnetic shielding efficiency of the material. The wood fiber has the remarkable advantages of wide sources, environmental friendliness and high yield of carbonized products, and the prepared carbon has a developed pore structure, is easy to regulate and control, and is beneficial to preparing high-performance electromagnetic shielding materials. However, the products of carbonized wood fiber raw materials are amorphous carbon with a structure which is difficult to graphitize, and effective graphitization conversion is still difficult to occur even when the products are heated to 3000 ℃, so that the invention aims at the problem, Ni is used as a catalyst, graphitization of the wood fiber raw materials can be realized at a relatively low temperature (for example 1400 ℃), and the prepared graphitized samples have good conductivity and a developed pore structure, and are beneficial to preparation of electromagnetic shielding materials.
Disclosure of Invention
The invention aims to provide a preparation method of a wood fiber-based electromagnetic shielding carbon material with high efficiency and low energy consumption.
The invention provides a wood fiber-based graphitized material which has good shielding effect on X-band (2-18 GHz) electromagnetic waves and is obtained by adopting Ni as a catalyst to enable wood fiber raw materials to be subjected to effective graphitization conversion at a relatively low temperature.
A preparation method of biomass-based graphitized material comprises the following steps:
firstly, carbonizing wood fiber raw materials and loading a metal catalyst: the wood fiber raw material is processed by closed high-temperature carbonization, and the product is dipped in Ni2+Is dissolved in waterDrying the solution to obtain Ni-loaded carbon;
step two, graphitization reaction: and (3) carrying out high-temperature reaction on the Ni-loaded carbon in a closed environment for a certain time, converting the Ni into simple substance Ni due to the reduction action of the carbon, further carrying out catalytic graphitization reaction, and cooling to obtain the final product, namely the bio-based graphitized material.
The loading amount of the metal Ni is 2-5 mmol/g;
the temperature of the second step catalytic graphitization reaction is 1200-1600 ℃.
The catalytic graphitization reaction time is 2-5 h.
The first step carbonization temperature is 400-600 ℃.
Has the advantages that:
1. the Ni catalysis method can effectively graphitize the wood fiber raw material which is difficult to graphitize at a relatively low temperature, which is significantly lower than 2800 ℃ required by the traditional graphitization. The obtained product can achieve complete graphitization conversion, the crystallinity is close to natural graphite, and the electromagnetic shielding effectiveness of the product in an X wave band (8-12 GHz) can exceed 60 dB.
2. After the graphitization reaction, the metal as the catalyst exists in a simple substance form, which is beneficial to improving the electromagnetic shielding efficiency of the product, and simultaneously, the step of concentrated acid washing is avoided, so that the preparation process is green and environment-friendly.
Drawings
FIG. 1 is an XRD spectrum of cellulose and lignin after graphitization treatment.
Fig. 2 is a TEM photograph of cellulose and lignin after graphitization treatment.
FIG. 3 shows the shielding effectiveness of the product against electromagnetic waves in the X-band.
Detailed Description
A preparation method of a wood fiber-based electromagnetic shielding carbon material with high efficiency and low energy consumption comprises the following specific steps:
(1) respectively placing cellulose and lignin in a closed crucible, and carbonizing at 400 deg.C for 1 h. Weighing the product and soaking the product in Ni2+After overnight, dried at 140 ℃ until ready for use.
(2) Putting the Ni-loaded carbon into a high-temperature resistant closed crucible, putting the crucible into a high-temperature furnace for reaction for a certain time, and cooling to obtain a final product.
The method for preparing the wood fiber-based electromagnetic shielding carbon material is green and environment-friendly, Ni is used as a catalyst, the wood fiber raw material which is still difficult to graphitize and convert by a conventional high-temperature graphitization method can be effectively graphitized and converted at a relatively low temperature, and after the graphitization treatment, metal exists in a simple substance form, so that the electromagnetic shielding efficiency of a product is improved, and the risk of secondary pollution caused by washing the metal by a large amount of concentrated acid is avoided.
The preparation method of the wood fiber-based electromagnetic shielding carbon material comprises the following steps:
firstly, carbonizing wood fiber raw materials and loading a metal catalyst: placing the lignocellulose raw material in a closed crucible, and carrying out carbonization treatment for 1h at 400-600 ℃. Impregnating the product with a solution containing a certain amount of Ni2+After overnight, drying for use;
secondly, putting the carbon loaded with Ni into a high-temperature resistant closed crucible, putting the crucible into a high-temperature furnace for reaction for a certain time to fully perform graphitization reaction, and cooling to obtain a final product.
The loading amount of the metal Ni is 2-5 mmol/g C;
the graphitization reaction temperature is 1200-1600 ℃;
the graphitization reaction time is 2-5 h.
Aiming at the problem that the wood fiber raw material is difficult to graphitize by the conventional method, the product with higher graphitization degree is successfully prepared by adopting the Ni catalytic method, has a graphite structure with more than 40 layers, and has the temperature greatly lower than 2800 ℃ required by the conventional graphitization. In addition, the obtained product has better conductivity, the shielding effectiveness of the product on an X wave band can exceed 60dB, and the product has good application prospect.
Example 1:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+Is added to the aqueous solution of (a) overnight,then dried at 140 ℃ until ready for use, at which point the Ni loading in the carbon sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1200 ℃ to react for 3h to obtain a final product. The graphitization degree of the product is calculated to be 43.6%, and the shielding effectiveness of the product on an X wave band can reach 43dB at most.
Example 2:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 3h to obtain a final product. The graphitization degree of the product is calculated to be 62.7%, and the shielding effectiveness of the product on an X wave band can reach 52dB at most.
Example 3:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, heating to 1600 ℃, and reacting for 3 hours to obtain a final product. The graphitization degree of the product is calculated to be 69.2%, and the shielding effectiveness of the product on an X wave band can reach 62dB at most.
Example 4:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 4 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 3h to obtain a final product. The graphitization degree of the product is 57.1 percent through calculation, and the shielding effectiveness of the product on an X wave band can reach 47dB at most.
Example 5:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking in a solution containingA certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 10 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 3h to obtain a final product. The graphitization degree of the product is calculated to be 68.4%, and the shielding effectiveness of the product on an X wave band can reach 60dB at most.
Example 6:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 2h to obtain a final product. The graphitization degree of the product is calculated to be 61.3%, and the shielding effectiveness of the product on an X wave band can reach 59dB at most.
Example 7:
placing the cellulose in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 5 hours to obtain a final product. The graphitization degree of the product is calculated to be 70.5%, and the shielding effectiveness of the product on an X wave band can reach 66dB at most.
Example 8:
putting the lignin in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1200 ℃ to react for 3h to obtain a final product. The graphitization degree of the product is 39.7 percent through calculation, and the shielding effectiveness of the product on an X wave band can reach 38dB at most.
Example 9:
placing lignin in a sealed crucible, and carbonizing at 400 deg.CAnd treating for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 3h to obtain a final product. The graphitization degree of the product is calculated to be 54.2%, and the shielding effectiveness of the product on an X wave band can reach 59dB at most.
Example 10:
putting the lignin in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, heating to 1600 ℃, and reacting for 3 hours to obtain a final product. The graphitization degree of the product is calculated to be 61.5%, and the shielding effectiveness of the product on an X wave band can reach 64dB at most.
Example 11:
putting the lignin in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 4 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 3h to obtain a final product. The graphitization degree of the product is calculated to be 56.8%, and the shielding effectiveness of the product on an X wave band can reach 58dB at most.
Example 12:
putting the lignin in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 10 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 3h to obtain a final product. The graphitization degree of the product is 57.7 percent through calculation, and the shielding effectiveness of the product on an X wave band can reach 65dB at most.
Example 13:
putting the lignin in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 2h to obtain a final product. The graphitization degree of the product is calculated to be 56.4%, and the shielding effectiveness of the product on an X wave band can reach 63dB at most.
Example 14:
putting the lignin in a closed crucible, and carbonizing at 400 ℃ for 1 h. Weighing 2g of carbonized product, and soaking the carbonized product in a solution containing a certain amount of Ni2+After overnight drying at 140 c until ready for use, the Ni loading in the charcoal sample was 6 mmol. Putting the Ni-loaded carbon into a high-temperature-resistant closed crucible, putting the crucible into a high-temperature furnace, and heating to 1400 ℃ for reaction for 5 hours to obtain a final product. The graphitization degree of the product is calculated to be 59.6%, and the shielding effectiveness of the product on an X wave band can reach 63dB at most.

Claims (6)

1. A wood fiber-based graphitized material is characterized by having good shielding effect on X-band (2-18 GHz) electromagnetic waves, and being obtained by adopting Ni as a catalyst to enable wood fiber raw materials to undergo effective graphitization conversion at a relatively low temperature.
2. The method of making a biomass-based graphitized material of claim 1 comprising the steps of:
firstly, carbonizing wood fiber raw materials and loading a metal catalyst: the wood fiber raw material is processed by closed high-temperature carbonization, and the product is dipped in Ni2+Then drying to obtain Ni-loaded carbon;
step two, graphitization reaction: and (3) carrying out high-temperature reaction on the Ni-loaded carbon in a closed environment for a certain time, converting the Ni into simple substance Ni due to the reduction action of the carbon, further carrying out catalytic graphitization reaction, and cooling to obtain the final product, namely the bio-based graphitized material.
3. The method for preparing a wood fiber-based electromagnetic shielding carbon material as claimed in claim 2, wherein the amount of Ni loaded is 2 to 5 mmol/g.
4. The method for preparing a wood fiber-based electromagnetic shielding carbon material as claimed in claim 2, wherein the temperature of the second catalytic graphitization reaction is 1200-1600 ℃.
5. The method for preparing the wood fiber-based electromagnetic shielding carbon material as claimed in claim 2, wherein the catalytic graphitization reaction time is 2-5 h.
6. The method for preparing the wood fiber-based electromagnetic shielding carbon material as claimed in claim 2, wherein the first carbonization temperature is 400-600 ℃ and the carbonization time is 1 h.
CN202011509002.5A 2020-12-18 2020-12-18 Preparation method of wood fiber-based electromagnetic shielding carbon material Pending CN112788934A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102502598A (en) * 2011-10-25 2012-06-20 合肥工业大学 Catalytic graphitization method for wood powder
CN106744915A (en) * 2016-12-16 2017-05-31 中国林业科学研究院林产化学工业研究所 A kind of cellulose base graphitized material and preparation method thereof
CN109092279A (en) * 2018-08-31 2018-12-28 中国林业科学研究院林产化学工业研究所 A kind of highly effective cellulose base class graphene/TiO2Composite photo-catalyst and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102502598A (en) * 2011-10-25 2012-06-20 合肥工业大学 Catalytic graphitization method for wood powder
CN106744915A (en) * 2016-12-16 2017-05-31 中国林业科学研究院林产化学工业研究所 A kind of cellulose base graphitized material and preparation method thereof
CN109092279A (en) * 2018-08-31 2018-12-28 中国林业科学研究院林产化学工业研究所 A kind of highly effective cellulose base class graphene/TiO2Composite photo-catalyst and preparation method thereof

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Application publication date: 20210511