A lignin-based carbon ceramic framework, its preparation method and application

Abstract

The present invention relates to a lignin-based carbon ceramic framework and its preparation method and application. In the present invention, DES is used to dissolve and disperse lignin. By adding nano iron powder and metal hydroxide precursors, and using epoxy resin to construct a lignin-based carbon ceramic framework precursor, an in-situ lignin-based carbon ceramic framework is obtained under high-temperature calcination. Then, a phase change heat-conducting composite material is prepared with the lignin-based carbon ceramic framework as the heat-conducting framework and polyethylene glycol as the matrix. The phase change composite material of the present invention is composed of a lignin-based carbon ceramic framework and a polyethylene glycol matrix with different molecular weights. The composite material exhibits a relatively high thermal conductivity, with a thermal conductivity of up to 1.5 - 4.6 W·m-1·K-1, a phase change enthalpy of 160.4 - 177.6 J·g-1, and in addition, the compressive strength can reach 7.3 - 13.2 MPa.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermally conductive composite materials, and relates to a lignin-based carbon ceramic framework and a preparation method and application thereof. Background Art

[0002] With the development of technology and the continuous improvement of semiconductor and microelectronic integration technologies, the power density per unit area of electronic devices and industrial equipment has increased sharply. The rapid accumulation of heat inside the equipment will lead to a decline in performance and seriously affect the reliability and accuracy of the equipment. Therefore, effectively transferring the heat accumulated inside the equipment has become an urgent problem to be solved, and developing high-performance thermally conductive composite materials for effectively conducting heat will be an effective way to solve this problem.

[0003] The traditional preparation method of thermally conductive composite materials is to directly blend thermally conductive fillers and polymer matrices. Due to the difficult-to-control distribution state of the fillers, the thermal conductivity of the composite materials prepared by this method can no longer meet the requirements of industrial applications. Compared with this method, methods such as 3D molding and ice templating can effectively control the dispersion of thermally conductive particles and construct an efficient thermal conduction framework, but these methods are limited by the cumbersome process flow and high preparation cost and are still difficult to apply in practice.

[0004] In addition, the increasing consumption of non-renewable fossil energy has also brought severe energy and resource crises. Lignin is derived from plants and is the second most abundant natural organic polymer, second only to cellulose in content. It has a carbon content as high as 60% and is an ideal carbon precursor material. Therefore, it is of great significance to use the biomass resource lignin as a precursor to prepare thermally conductive composite materials. There is no existing technology that uses lignin to construct a three-dimensional thermal conduction framework to improve the thermal conductivity of materials. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art during the preparation of the thermal conduction framework, such as the cumbersome and complex preparation process flow, high cost, and less-than-ideal thermal conductivity. Therefore, a method for preparing a carbon ceramic framework using lignin as a raw material is provided. It can in-situ generate a network framework of metal oxides and lignin carbon, which is beneficial to constructing phonon transmission channels, thereby effectively improving the thermal conductivity of the composite material, and the preparation process is simple and the cost is low, suitable for large-scale industrial production.

[0006] To achieve the above purpose, the present invention is realized by the following means:

[0007] The first aspect of the present invention provides a preparation method of a lignin-based carbon ceramic framework, including the following steps:

[0008] (1) Add a hydrogen bond donor compound and a hydrogen bond acceptor compound into a container, and fully stir at room temperature to obtain a DES solvent;

[0009] (2) Add the lignin raw material to the DES solvent obtained in step (1) and stir to fully dissolve it. Then add a catalyst and a metal hydroxide and stir well. Next, add an epoxy resin and a curing agent, stir evenly, and place it in a mold for two-stage hot pressing and curing to obtain a lignin-based ceramic skeleton precursor.

[0010] (3) Place the lignin-based ceramic skeleton precursor obtained in step (2) in a tubular furnace for calcination, then wash and dry it to obtain the lignin-based ceramic skeleton.

[0011] Preferably, the hydrogen bond donor compound in step (1) is selected from one or more of phenol, hydroquinone, resorcinol, and ethylene glycol; the hydrogen bond acceptor compound is selected from one or more of maleic anhydride, glutaric anhydride, and citraconic anhydride.

[0012] Preferably, the mass ratio of the hydrogen bond donor compound to the hydrogen bond acceptor compound in step (1) is 0.1-1.8.

[0013] Preferably, the stirring time in step (1) is 30-90 min.

[0014] Preferably, the lignin raw material in step (2) is selected from one or more of alkali lignin, sodium lignosulfonate, and enzyme-hydrolyzed lignin.

[0015] Preferably, the dosage of the lignin raw material in step (2) accounts for 16.24%-34.69% of the total mass of the lignin-based ceramic skeleton precursor.

[0016] Preferably, the catalyst in step (2) is selected from iron powder; more preferably, the catalyst is selected from nano iron powder.

[0017] Preferably, the dosage of the catalyst in step (2) is 3-5% of the mass of the lignin raw material.

[0018] Preferably, the metal hydroxide in step (2) is selected from Al(OH) 3 、Mg(OH) 2 、Zn(OH) 2 、B(OH) 3 or one or more of them.

[0019] Preferably, the dosage of the metal hydroxide in step (2) accounts for 16.76%-39% of the total mass of the lignin-based ceramic skeleton precursor.

[0020] Preferably, the epoxy resin in step (2) is selected from one or more of E44, E41, and E54.

[0021] Preferably, the amount of the epoxy resin described in step (2) accounts for 10.14%-21.65% of the total mass of the lignin-based ceramic skeleton precursor.

[0022] Preferably, the curing agent described in step (2) is selected from one or more of DDM and PACM.

[0023] Preferably, the mass ratio of the curing agent to the epoxy resin in step (2) is 1:3-12.

[0024] Preferably, the conditions of the two-stage hot pressing and curing in step (2) are specifically as follows: the temperature of the first stage is 60-100°C, and the time is 1-5h; the temperature of the second stage is 150-180°C, and the time is 1-5h.

[0025] Preferably, the conditions of the calcination in step (3) are as follows: heating to 600-1200°C at a heating rate of 1-10°C / min and calcining for 60-120min.

[0026] Preferably, the calcination in step (3) is carried out under a protective gas.

[0027] Preferably, the protective gas is selected from one or more of ammonia gas, argon gas, and nitrogen gas.

[0028] Preferably, the calcination in step (3) can be optionally repeated 1-2 times; the conditions of each repeated calcination can be the same or different from those of the previous calcination; it is necessary to cool to room temperature before each repeated calcination.

[0029] Preferably, the washing in step (3) is specifically carried out by washing with deionized water 1-3 times.

[0030] Preferably, the drying in step (3) is carried out under vacuum conditions, the drying temperature is 50-100°C, and the drying time is 12-48h.

[0031] The second aspect of the present invention provides a lignin-based ceramic skeleton prepared according to the above preparation method.

[0032] The third aspect of the present invention provides a phase change heat conduction composite material, which includes a lignin-based ceramic skeleton prepared according to the above preparation method and a polymer matrix.

[0033] Preferably, the polymer matrix is selected from polyethylene glycol (PEG); more preferably, the polymer matrix is selected from polyethylene glycol with a molecular weight of 4000-10000; most preferably, the polymer matrix is selected from one or more of PEG-4000, PEG-8000, and PEG-10000.

[0034] Preferably, the phase change heat conductive composite material is prepared by the following method: placing the lignin-based carbon ceramic heat conductive framework in a mold, adding a polymer matrix and / or a curing agent for vacuum impregnation, and then performing curing and / or cooling to obtain the composite material.

[0035] Regarding the three-dimensional framework of lignin-based carbon ceramics involved in the present invention, first, a deep eutectic solvent (DES) is prepared with a compound having a hydrogen bond donor and an acceptor, then lignin is dissolved and dispersed, and then nano iron powder, epoxy resin / curing agent, and metal hydroxide are added. After thermal curing, a precursor of the lignin-based carbon ceramic framework is prepared. During the calcination process of this precursor, a carbon-based ceramic network framework containing metal oxides is in-situ generated. This framework structure has a three-dimensional porous structure and is conducive to the formation of an efficient carbon-ceramic heat conduction network. Compared with the traditional heat conductive framework construction method, it can in-situ generate a network framework of metal oxides and lignin carbon, which is conducive to constructing a phonon transmission channel, thereby effectively improving the heat conduction performance of the composite material.

[0036] The present invention has the following beneficial effects compared with the existing technology:

[0037] (1) The present invention uses biomass lignin, which is widely sourced and low-cost, as a carbon source, and uses metal hydroxide as a ceramic precursor to in-situ prepare a lignin-based carbon ceramic network framework. This framework has a porous network structure, and continuous lignin carbon and metal oxides can provide an effective channel for phonon transmission, effectively realizing the high-value application of lignin.

[0038] (2) The present invention uses the lignin-based carbon ceramic framework as a heat conductive framework and different polymers as matrices to prepare functional heat conductive composite materials, which can effectively improve the heat conduction performance and interfacial heat transfer of the polymer matrix. The thermal conductivity can reach 1.5 - 4.6 W·m -1 ·K -1 , the phase change enthalpy reaches 160.4 - 177.6 J·g -1 , and in addition, the compressive strength can reach 7.3 - 13.2 MPa. Description of the Drawings

[0039] Figure 1 It is a scanning electron microscope image of the lignin carbon / BN heat conductive framework prepared in Example 4 of the present invention.

[0040] Figure 2 It is an X-ray diffraction pattern of the lignin carbon / BN heat conductive framework prepared in Example 4 of the present invention. Detailed Embodiments

[0041] To make the objectives, technical solutions and effects of the present invention clearer and more definite, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0043] Example 1

[0044] A lignin-based carbon ceramic skeleton, and its preparation method specifically includes the following steps:

[0045] (1) Add 1.376 g of resorcinol and 2.451 g of maleic anhydride into a 25 mL beaker, and magnetically stir for 60 min at room temperature (25 °C) to obtain a DES solvent.

[0046] (2) Take 4.8 g of sodium lignosulfonate (LS) and add it to the DES solvent obtained in step (1), stir to fully dissolve, then add 0.144 g of nano iron powder and 3.6 g of aluminum hydroxide (Al(OH) 3 ) and stir for 30 min until evenly dispersed, then add 1.5 g of E44 epoxy resin and 0.327 g of 4,4'-diaminodiphenylmethane (DDM), stir at 50 °C for 15 min, transfer to a 25×25×5 mm mold, and hot press and cure at 80 °C for 1 h, then hot press and cure at 150 °C for 3 h to obtain a lignin-based carbon ceramic skeleton precursor.

[0047] (3) Place the lignin-based carbon ceramic skeleton precursor obtained in step (2) in a tube furnace, under nitrogen protection, heat it to 600 °C at a heating rate of 2 °C / min and calcine for 60 min, take it out after cooling and wash it 3 times with deionized water, and place it in a vacuum dryer at 100 °C for 12 h to obtain a lignin carbon / Al 2 O 3 thermal conductive skeleton.

[0048] Furthermore, use the lignin carbon / Al 2 O 3 thermal conductive skeleton prepared by the above method to prepare a phase change thermal conductive composite material, which specifically includes the following steps: The lignin carbon / Al in step (3) 2 O 3The heat-conducting framework is placed in a mold of 25×25×5 mm. 10 g of polyethylene glycol-8000 (PEG-8000) is melted at 80 °C and impregnated into the lignin carbon / Al 2 O 3 heat-conducting framework by means of reduced pressure, and then cooled to room temperature to obtain the product.

[0049] Example 2

[0050] A lignin carbon-based ceramic framework and its preparation method specifically include the following steps:

[0051] (1) Add 2.355 g of phenol and 2.802 g of citraconic anhydride to a 25 mL beaker, and magnetically stir for 30 min at room temperature (25 °C) to obtain a DES solvent.

[0052] (2) Take 7.209 g of alkali lignin (AL) and add it to the DES solvent obtained in step (1), stir to fully dissolve it, then add 0.216 g of nano iron powder and 4.81 g of magnesium hydroxide (Mg(OH) 2 ) and stir for 30 min until evenly dispersed. Then add 3 g of E51 epoxy resin and 0.38 g of 4,4'-diaminodiphenylmethane (DDM), stir at 50 °C for 15 min, transfer to a mold of 25×25×5 mm, hot press and cure at 100 °C for 2 h, and then hot press and cure at 170 °C for 2 h to obtain a lignin carbon-based ceramic framework precursor.

[0053] (3) Place the lignin carbon-based ceramic framework precursor obtained in step (2) in a tubular furnace. Under argon protection, heat it to 750 °C at a heating rate of 1 °C / min and calcine for 60 min. After cooling, take it out and wash it 3 times with deionized water, and place it in a vacuum dryer at 70 °C for 24 h to obtain a lignin carbon / MgO heat-conducting framework.

[0054] Furthermore, the lignin carbon / MgO heat-conducting framework prepared by the above method is used to prepare a phase change heat-conducting composite material, which specifically includes the following steps: Place the lignin carbon / MgO heat-conducting framework in step (3) in a mold of 25×25×5 mm. 10 g of polyethylene glycol-10000 (PEG-10000) is melted at 80 °C and impregnated into the lignin carbon / Al 2 O 3 heat-conducting framework by means of reduced pressure, and then cooled to room temperature to obtain the product.

[0055] Example 3

[0056] A lignin carbon-based ceramic framework and its preparation method specifically include the following steps:

[0057] (1) Add 4.404 g of hydroquinone and 9.128 g of glutaric anhydride into a 25 mL beaker, and magnetically stir for 40 min at room temperature (25 °C) to obtain the DES solvent.

[0058] (2) Take 10.8 g of enzyme hydrolyzed lignin (EHL) and add it to the DES solvent obtained in step (1), stir to fully dissolve it, then add 0.378 g of nano iron powder and 6.2 g of zinc hydroxide (Zn(OH) 2 ) and stir for 30 min until evenly dispersed. Then add 5 g of E44 epoxy resin and 1.089 g of 4,4'-diaminodiphenylmethane (DDM), stir at 50 °C for 15 min, transfer to a 25×25×5 mm mold, and hot press and cure at 100 °C for 2 h, then hot press and cure at 150 °C for 2 h to obtain the lignin carbon-based ceramic skeleton precursor.

[0059] (3) Place the lignin carbon-based ceramic skeleton precursor obtained in step (2) in a tube furnace, under argon protection, heat it to 800 °C at a heating rate of 3 °C / min and calcine for 90 min. After cooling, take it out and wash it 3 times with deionized water, and place it in a vacuum dryer at 50 °C for 48 h to obtain the lignin carbon / ZnO thermal conductive skeleton.

[0060] Furthermore, use the lignin carbon / ZnO thermal conductive skeleton prepared by the above method to prepare a thermal conductive composite material, which specifically includes the following steps: Place the lignin carbon / ZnO thermal conductive skeleton in step (3) in a 25×25×5 mm mold, melt 10 g of polyethylene glycol-8000 (PEG-8000) at 80 °C and impregnate it into the lignin carbon / Al 2 O 3 thermal conductive skeleton by means of reduced pressure, and cool it to room temperature to obtain it.

[0061] Example 4

[0062] A lignin carbon-based ceramic skeleton, and its preparation method specifically includes the following steps:

[0063] (1) Add 1.979 g of ethylene glycol and 2.451 g of maleic anhydride into a 25 mL beaker, and magnetically stir for 90 min at room temperature (25 °C) to obtain the DES solvent.

[0064] (2) Take 7.209 g of alkali lignin (AL) and add it to the DES solvent obtained in step (1), stir to fully dissolve it, then add 0.324 g of nano iron powder and 9.612 g of B(OH) 3Stir for 30 min until uniformly dispersed, then add 2.5 g of E44 epoxy resin and 0.577 g of 4,4'-diaminodicyclohexylmethane (PACM), stir at 50 °C for 15 min, transfer to a mold of 25×25×5 mm, and hot press and cure at 60 °C for 3 h, then hot press and cure at 150 °C for 1 h to obtain a lignin-based carbon ceramic framework precursor.

[0065] (3) Place the lignin-based carbon ceramic framework precursor obtained in step (2) in a tubular furnace, under argon protection, heat it to 950 °C at a heating rate of 10 °C / min and calcine for 60 min. After cooling, under ammonia protection, heat it to 1100 °C at a heating rate of 10 °C / min and calcine for 60 min. After cooling, take it out and wash it 3 times with deionized water, and place it in a vacuum dryer at 80 °C for 24 h to obtain a lignin carbon / BN thermal conductive framework. Its scanning electron microscope image and X-ray diffraction pattern are respectively as Figure 1-2 shown.

[0066] Furthermore, the lignin carbon / BN thermal conductive framework prepared by the above method is used to prepare a phase change thermal conductive composite material, which specifically includes the following steps: Place the lignin carbon / BN thermal conductive framework in step (3) in a mold of 25×25×5 mm, melt 10 g of polyethylene glycol-4000 (PEG-4000) at 80 °C and impregnate it into the lignin carbon / BN thermal conductive framework by means of reduced pressure, and cool to room temperature to obtain it.

[0067] Example 5

[0068] A lignin-based carbon ceramic framework, and its preparation method specifically includes the following steps:

[0069] (1) Add 3.103 g of ethylene glycol and 11.208 g of citraconic anhydride to a 25 mL beaker, and magnetically stir at room temperature (25 °C) for 60 min to obtain a DES solvent.

[0070] (2) Take 6 g of alkali lignin (AL) and add it to the DES solvent obtained in step (1) and stir to fully dissolve it. Then add 0.300 g of nano iron powder and 6.2 g of magnesium hydroxide (Mg(OH) 2 ) and stir for 30 min until uniformly dispersed, then add 8 g of E54 epoxy resin and 2.134 g of 4,4'-diaminodiphenylmethane (DDM), stir at 50 °C for 15 min, transfer to a mold of 25×25×5 mm, and hot press and cure at 100 °C for 3 h, then hot press and cure at 180 °C for 1 h to obtain a lignin-based carbon ceramic framework precursor.

[0071] (3) Place the lignin carbon-based ceramic framework precursor obtained in step (2) in a tube furnace. Under nitrogen protection, heat it at a heating rate of 2 °C / min to 1100 °C and calcine for 90 min. After cooling, take it out and wash it 3 times with deionized water, and place it in a vacuum dryer at 90 °C for 24 h to obtain the lignin carbon / MgO thermal conductivity framework.

[0072] Further, prepare a phase change thermal conductivity composite material with the lignin carbon / MgO thermal conductivity framework prepared by the above method. The specific steps are as follows: Place the lignin carbon / MgO thermal conductivity framework in step (3) in a mold of 25×25×5 mm. Melt 10 g of polyethylene glycol-10000 (PEG-10000) at 80 °C and impregnate it into the lignin carbon / Al 2 O 3 thermal conductivity framework by means of reduced pressure, and cool it to room temperature to obtain.

[0073] Example 6

[0074] A lignin carbon-based ceramic framework, and its preparation method specifically includes the following steps:

[0075] (1) Add 2 g of hydroquinone and 4.072 g of citraconic anhydride to a 25 mL beaker, and magnetically stir for 50 min at room temperature (25 °C) to obtain a DES solvent.

[0076] (2) Take 7.209 g of enzyme hydrolyzed lignin (EHL) and add it to the DES solvent obtained in step (1), stir to fully dissolve it, then add 0.360 g of nano iron powder and 9.612 g of B(OH) 3 Stir for 30 min until evenly dispersed, then add 3.5 g of E44 epoxy resin and 0.323 g of 4,4'-diaminodicyclohexylmethane (PACM), stir at 50 °C for 15 min, transfer it to a mold of 25×25×5 mm, hot press and cure at 60 °C for 4 h, and then hot press and cure at 150 °C for 2 h to obtain a lignin carbon-based ceramic framework precursor.

[0077] (3) Place the lignin carbon-based ceramic framework precursor obtained in step (2) in a tube furnace. Under argon protection, heat it at a heating rate of 5 °C / min to 1000 °C and calcine for 120 min. After cooling, under ammonia protection, heat it at a heating rate of 5 °C / min to 1200 °C and calcine for 60 min. After cooling, take it out and wash it 3 times with deionized water, and place it in a vacuum dryer at 60 °C for 48 h to obtain the lignin carbon / BN thermal conductivity framework.

[0078] Further, a phase change heat conduction composite material is prepared using the lignin carbon / BN heat conduction framework prepared by the above method, which specifically includes the following steps: Place the lignin carbon / BN heat conduction framework in step (3) in a mold of 25×25×5 mm, melt 10 g of polyethylene glycol-10000 (PEG-10000) at 80°C and impregnate it into the lignin carbon / Al 2 O 3 heat conduction framework by means of reduced pressure, and cool it to room temperature to obtain the product.

[0079] Comparative Example 1

[0080] A lignin carbon-based ceramic framework, and its preparation method specifically includes the following steps:

[0081] (1) Add 1.376 g of resorcinol and 2.451 g of maleic anhydride to a 25 mL beaker, and magnetically stir for 60 min at room temperature (25°C) to obtain a DES solvent.

[0082] (2) Take 4.8 g of sodium lignosulfonate (LS) and add it to the DES solvent obtained in step (1), stir for 30 min until uniformly dispersed, then add 1.5 g of E44 epoxy resin and 0.327 g of 4,4'-diaminodiphenylmethane (DDM), stir at 50°C for 15 min, transfer to a mold of 25×25×5 mm, hot press and cure at 80°C for 1 h, and then hot press and cure at 150°C for 3 h to obtain a lignin carbon precursor.

[0083] (3) Place the lignin carbon precursor obtained in step (2) in a tube furnace, under nitrogen protection, heat it to 600°C at a heating rate of 2°C / min and calcine for 60 min, take it out after cooling and wash it 3 times with deionized water, and place it in a vacuum dryer at 100°C for 12 h to obtain a lignin carbon heat conduction framework.

[0084] Further, a heat conduction composite material is prepared using the lignin carbon heat conduction framework prepared by the above method, which specifically includes the following steps: Place the lignin carbon heat conduction framework in step (3) in a mold of 25×25×5 mm, melt 10 g of polyethylene glycol-10000 (PEG-10000) at 80°C and impregnate it into the lignin carbon heat conduction framework by means of reduced pressure, and cool it to room temperature to obtain the product.

[0085] Verification Example 1

[0086] Respectively take the heat conduction composite materials prepared in Examples 1-6 and Comparative Example 1, and detect their heat conduction performance, mechanical performance, phase change enthalpy, and melting temperature (tested according to ISO 22007-2, ASTM D3574, and ASTM C1784 standards respectively). The detection results are shown in Table 1 below.

[0087] Table 1 Thermal conductivity, phase change enthalpy and compressive strength of the thermally conductive composites prepared in Examples 1-6

[0088]

[0089]

[0090] The results show that in Comparative Example 1, the degree of graphitization is low and the carbon skeleton network does not contain thermally conductive particles, so that the thermal conductivity of the composite material is only 0.52 W·m -1 ·K -1 , the phase change enthalpy is 157.1 J·g -1 , and the compressive strength is 3.5 MPa. For the phase change thermally conductive composite material prepared according to the examples of the present invention, its thermal conductivity, phase change enthalpy value and compressive strength have all been significantly improved.

[0091] The above specific embodiments have specifically introduced the analysis method involved in the present invention. It should be noted that the above introduction is only to help those skilled in the art better understand the method and idea of the present invention, rather than a limitation on the relevant content. Without departing from the principle of the present invention, those skilled in the art can also make appropriate adjustments or modifications to the present invention, and the above adjustments and modifications should also fall within the protection scope of the present invention.

Claims

1. A preparation method of a lignin-based carbon ceramic skeleton, characterized in that, it comprises the following steps: (1) Add a hydrogen bond donor compound and a hydrogen bond acceptor compound into a container, and stir well at room temperature to obtain a deep eutectic solvent; the hydrogen bond donor compound is selected from one or more of phenol, hydroquinone, resorcinol, and ethylene glycol; the hydrogen bond acceptor compound is selected from one or more of maleic anhydride, glutaric anhydride, and citraconic anhydride; (2) Add the lignin raw material to the deep eutectic solvent obtained in step (1) and stir to fully dissolve it. Then add a catalyst and a hydroxide and stir well. Next, add epoxy resin and a curing agent, stir evenly, and place it in a mold for two-stage hot pressing and curing to obtain a lignin-based ceramic skeleton precursor; the catalyst is selected from iron powder; the hydroxide is selected from one or more of Al(OH) 3 , Mg(OH) 2 , Zn(OH) 2 , B(OH) 3 ; (3) Place the lignin-based carbon ceramic skeleton precursor obtained in step (2) in a tube furnace for calcination, and then wash and dry to obtain the lignin-based carbon ceramic skeleton.

2. The preparation method according to claim 1, characterized in that, the lignin raw material in step (2) is selected from one or more of alkali lignin, sodium lignosulfonate, and enzyme-hydrolyzed lignin.

3. The preparation method according to claim 1, characterized in that, the catalyst in step (2) is selected from nano iron powder.

4. The preparation method according to claim 1, characterized in that, the curing agent in step (2) is selected from one or more of 4,4'-diaminodiphenylmethane and 4,4'-diaminodicyclohexylmethane.

5. The preparation method according to claim 1, characterized in that, the conditions of the two-stage hot pressing and curing in step (2) are specifically: the first stage temperature is 60 - 100 °C, and the time is 1 - 5 h; the second stage temperature is 150 - 180 °C, and the time is 1 - 5 h.

6. A lignin-based carbon ceramic skeleton prepared by the preparation method according to any one of claims 1 - 5.

7. A phase change heat conduction composite material, characterized in that, it comprises a lignin-based carbon ceramic skeleton prepared by the preparation method according to any one of claims 1 - 5 and a polymer matrix.

8. The heat conduction composite material according to claim 7, characterized in that, the polymer matrix is selected from polyethylene glycol with a molecular weight of 4000 - 10000.

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