A method for preparing graphitized carbon material using biomass sugar-derived carbon

Abstract

The application provides a method for preparing graphitized carbon material by using biomass sugar-derived carbon, and the method comprises the following steps: (1) adding a crosslinking agent into water and stirring to mix uniformly, and then adding biomass sugar, acrylamide and a catalyst solution into the water in sequence and stirring to mix uniformly to obtain a mixed reaction solution; wherein the catalyst solution is a solution containing metal ions and nitrate ions; (2) adding an initiator into the mixed reaction solution and irradiating and curing under a UV lamp to obtain a gel reaction product; and (3) sequentially performing pre-carbonization, carbonization and graphitization treatment on the gel reaction product to obtain the graphitized carbon material. Compared with the graphitization temperature (above 2500 DEG C) of traditional biomass carbon material, the graphitized carbon material with regular graphite crystal structure can be successfully prepared at a relatively low temperature (1200-1500 DEG C).

Description

Technical Field

[0001] This invention relates to the field of graphitized carbon materials technology, and in particular to a method for preparing graphitized carbon materials using biomass sugar-derived carbon. Background Technology

[0002] With the rapid development of new energy, electronic devices, and environmental protection materials, the demand for high-performance graphitized carbon materials (such as graphite anodes, conductive fillers, and thermally conductive composite materials) has increased dramatically. Traditional graphitization processes rely on coal-based and petroleum-based precursors (such as needle coke and graphite pitch) for chemical coking, and their post-processing temperatures exceed 2500℃. This results in problems such as high energy consumption, unsustainable raw materials, and poor process compatibility. Meanwhile, biomass resources (such as cellulose, glucose, and lignin) are considered an ideal alternative to traditional fossil coking carbon sources due to their renewability, low cost, and low carbon emissions.

[0003] However, the graphitization of biomass-derived carbon faces many challenges. First, biomass carbon precursors are porous and contain heteroatoms, which easily lead to disordered carbon structure accumulation during high-temperature processing, resulting in deterioration of the electrical conductivity and mechanical properties of the carbon materials obtained from pyrolysis. Second, biomass carbon has poor thermal stability and is prone to structural collapse at high temperatures, making it difficult to precisely control the interlayer spacing and defect density. Finally, the process economy of biomass-derived carbon is low; traditional high-temperature processes cannot match the characteristics of biomass raw materials, resulting in high energy consumption and equipment costs, which restricts its industrial application.

[0004] Therefore, there is an urgent need to provide a method for preparing graphitized carbon materials using biomass sugar-derived carbon. Summary of the Invention

[0005] This invention provides a method for preparing graphitized carbon materials using biomass sugar-derived carbon, which solves the problems of excessively high temperatures, structural collapse, and poor electrical and mechanical properties of the resulting graphitized carbon materials in traditional biomass-derived carbon preparation processes.

[0006] In a first aspect, the present invention provides a method for preparing graphitized carbon materials using biomass sugar-derived carbon, the method comprising the following steps:

[0007] (1) Add the crosslinking agent to water and stir until well mixed. Then add biomass sugar, acrylamide and catalyst solution in sequence and stir until well mixed to obtain a mixed reaction solution. The catalyst solution is a solution containing metal ions and nitrate ions.

[0008] (2) Add an initiator to the mixed reaction solution and cure it under ultraviolet light to obtain a gel reaction product;

[0009] (3) The gel reaction product is subjected to pre-carbonization, carbonization and graphitization treatment in sequence to obtain the graphitized carbon material.

[0010] Preferably, in step (1), the crosslinking agent is N,N'-dimethylbisacrylamide, the biomass sugar is either glucose or sucrose, and the catalyst solution is ferric nitrate solution.

[0011] Preferably, in step (1), the mass ratio of crosslinking agent, acrylamide, biomass sugar and water is 1:(20-30):(80-100):(40-45).

[0012] More preferably, the mass concentration of the catalyst solution is 1-15%, and the mass ratio of the catalyst solution to biomass sugar is 1.6:(80-100).

[0013] Preferably, in step (2), the initiator is α-ketoglutaric acid.

[0014] More preferably, the mass ratio of the crosslinking agent to the initiator is 1:(0.25-0.75).

[0015] Preferably, in step (1), the temperature for stirring and mixing is 40-50℃, and the stirring time is 15-20min.

[0016] Preferably, in step (2), the UV lamp irradiation curing time is 1-2 minutes.

[0017] Preferably, in step (1), after obtaining the mixed reaction solution, the step further includes sonicating and centrifuging the mixed reaction solution.

[0018] Preferably, in step (3), the pre-carbonization temperature is 25-200℃ and the time is 50-55h.

[0019] Preferably, in step (3), the carbonization temperature is 700-800℃ and the time is 1.5-2.5h.

[0020] Preferably, in step (3), the graphitization is divided into a first heating stage and a second heating stage; wherein, the heating rate of the first heating stage is 4-5℃ / min, the heating temperature is 1000℃, the heating rate of the second heating stage is 3-4℃ / min, the heating temperature is 1200-1500℃, and the holding time is 1.5-2.5h.

[0021] In a second aspect, the present invention also provides a graphitized carbon material, which is prepared by any of the preparation methods described in the first aspect above.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] In this invention, biomass sugar is first used as a green carbon source, and acrylamide, catalyst solution, crosslinking agent, and initiator are introduced to construct a dual-network gel system under photocuring. Then, the gel system is sequentially subjected to pre-carbonization, carbonization, and graphitization treatments to obtain a carbon material with a low-defect graphitic structure. The addition of the catalyst solution not only promotes the curing of the gel system, but also allows metal ions and nitrate ions to synergistically promote the low-temperature graphitization of biomass sugar-derived carbon, significantly reducing the activation energy required for biomass sugar graphitization and greatly accelerating the graphitization process. Simultaneously, the catalyst solution synergistically interacts with the dual-network gel system. The gel network not only provides a high-stress environment for the metal ions and biomass sugar in the catalyst solution, making the catalytic effect of the catalyst solution more significant, but also effectively inhibits the generation of gaseous and volatile products. Furthermore, the metal ions and biomass sugar in the catalyst solution also prevent the gel network from deforming, avoiding structural collapse. Thus, compared to the graphitization temperature of traditional biomass carbon materials (above 2500℃), this invention can successfully prepare graphitized carbon materials with regular graphite crystal structures at relatively low temperatures (1200-1500℃). Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is an XRD pattern of graphitized carbon material prepared using biomass sugar-derived carbon, provided in Embodiment 1 of the present invention; in the figure, the horizontal axis is 2θ and the vertical axis is intensity;

[0026] Figure 2 This is a SEM image of a graphitized carbon material prepared using biomass sugar-derived carbon, provided in Embodiment 1 of the present invention.

[0027] Figure 3 This is a SEM image of a cross section of a graphitized carbon material prepared using biomass sugar-derived carbon, as provided in Embodiment 1 of the present invention.

[0028] Figure 4 This is a Raman spectrum of a graphitized carbon material prepared using biomass sugar-derived carbon, provided in Embodiment 3 of the present invention; in the figure, the horizontal axis represents wavelength and the vertical axis represents intensity.

[0029] Figure 5This is a hardness variation curve of graphitized carbon material prepared using biomass sugar-derived carbon, provided in Embodiment 5 of the present invention; in the figure, the horizontal axis represents the number of points, and the vertical axis represents hardness;

[0030] Figure 6 This is a Young's modulus variation curve of graphitized carbon material prepared using biomass sugar-derived carbon provided in Embodiment 5 of the present invention; in the figure, the horizontal axis is the number of points, and the vertical axis is the Young's modulus;

[0031] Figure 7 This is a Raman spectrum of a graphitized carbon material prepared using biomass sugar-derived carbon, provided in Comparative Example 3 of this invention; in the figure, the horizontal axis represents wavelength and the vertical axis represents intensity. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a method for preparing graphitized carbon materials using biomass sugar-derived carbon, the method comprising the following steps:

[0034] (1) Add the crosslinking agent to water and stir until well mixed. Then add biomass sugar, acrylamide and catalyst solution in sequence and stir until well mixed to obtain a mixed reaction solution. The catalyst solution is a solution containing metal ions and nitrate ions.

[0035] (2) Add an initiator to the mixed reaction solution and cure it under ultraviolet light to obtain a gel reaction product;

[0036] (3) The gel reaction product is subjected to pre-carbonization, carbonization and graphitization treatment in sequence to obtain the graphitized carbon material.

[0037] In this embodiment of the invention, biomass sugar is first used as a green carbon source, and acrylamide, catalyst solution, crosslinking agent, and initiator are introduced to construct a dual-network gel system under photocuring. Then, the gel system is sequentially subjected to pre-carbonization, carbonization, and graphitization treatments to obtain a carbon material with a low-defect graphite structure. The addition of the catalyst solution not only promotes the curing of the gel system, but also allows metal ions and nitrate ions to synergistically promote the low-temperature graphitization of biomass sugar-derived carbon, significantly reducing the activation energy required for biomass sugar graphitization and greatly accelerating the graphitization process. Simultaneously, the catalyst solution synergistically interacts with the dual-network gel system. The gel network not only provides a high-stress environment for the metal ions and biomass sugar in the catalyst solution, making the catalytic effect of the catalyst solution more significant, but also effectively inhibits the generation of gaseous and volatile products. Furthermore, the metal ions and biomass sugar in the catalyst solution also prevent the gel network from deforming, avoiding structural collapse. Thus, compared to the graphitization temperature of traditional biomass carbon materials (above 2500℃), this invention can successfully prepare graphitized carbon materials with regular graphite crystal structures at relatively low temperatures (1200-1500℃).

[0038] According to some preferred embodiments, in step (1), the crosslinking agent is N,N'-dimethylbisacrylamide, the biomass sugar is either glucose or sucrose, and the catalyst solution is ferric nitrate solution; in step (2), the initiator is α-ketoglutaric acid.

[0039] No prior art reports have been found regarding the preparation of high-performance graphitized carbon materials using biomass sugar as a carbon source at low temperatures (1200-1500℃). For example, although Chinese patent application CN 104176725A discloses a method for fixing carbon in sugars and preparing high-purity carbon (graphite) materials, this patent application uses ammonium persulfate aqueous solution as an initiator and triethanolamine or tetramethylethylene glycolamine solution as a catalyst to promote gel solidification. While the use of the above-mentioned catalysts can promote gel solidification, it will introduce new element sulfur into the gel system, thereby negatively affecting the performance of the final material. Furthermore, this patent application requires a high temperature (2800℃) to achieve the preparation of graphitized materials, and the degree of graphitization of the materials is low, resulting in poor mechanical properties. In this embodiment of the invention, extensive inventive experiments revealed that by introducing biomass sugar into an acrylamide gel system and further introducing ferric nitrate solution as a catalyst solution, while simultaneously using α-ketoglutarate to initiate gelation under ultraviolet light, the ferric nitrate solution not only promotes the gelation process of acrylamide, but α-ketoglutarate also reduces the ferric ions in the ferric nitrate solution to ferrous ions with better catalytic performance, thus facilitating the subsequent graphitization process of biomass sugar-derived carbon. Furthermore, the introduction of biomass sugar and catalyst solution into the gel system allows for a synergistic effect between the gel system and the biomass sugar and metallic iron ions. On one hand, the gel network provides a high-stress environment for the metallic iron ions and biomass sugar, making the catalytic effect of the metallic iron ions more significant, and effectively suppressing the generation of gaseous and volatile products. On the other hand, the metallic iron ions and biomass sugar also prevent the gel network from deforming, thereby avoiding structural collapse during the subsequent graphitization process. Thus, in this embodiment of the invention, graphitized carbon materials with good graphitization degree and good mechanical properties can be prepared at low temperature (1200-1500℃) using biomass sugar as a carbon source with a small amount of catalyst solution. Furthermore, experimental verification has shown that the graphitization degree of the graphitized carbon material obtained at 1400℃ in this embodiment of the invention is even greater than that of the graphitized carbon material obtained at 2500℃ in the aforementioned patent application.

[0040] According to some preferred embodiments, in step (1), the mass ratio of crosslinking agent, acrylamide, biomass sugar and water is 1:(20-30):(80-100):(40-45) (for example, it can be 1:20:80:40, 1:20:90:40, 1:20:100:40, 1:25:80:40, 1:25:90:40, 1:25:100:40, 1:30:80:40, 1:30:90:40, 1:30:100:40, 1:20:80:45, 1:20:80:45 or 1:20:100:45).

[0041] To prepare graphitized carbon materials with good performance, this embodiment of the invention prepares a mixed reaction solution with a high content of biomass sugar by mixing it with water. To avoid incomplete dissolution of some components during the preparation of the mixed reaction solution, which could adversely affect the performance of the final graphitized carbon material, this embodiment of the invention first adds a crosslinking agent to water and stirs it at a certain temperature until the solution becomes clear. Then, under stirring conditions, biomass sugar is added to the solution until it becomes completely clear before adding acrylamide and mixing. Finally, ferric nitrate solution is added and mixed to obtain a mixed reaction solution in which all components are completely dissolved. Furthermore, precise control of the proportions of each component facilitates the preparation of graphitized carbon materials with good mechanical properties and a high degree of graphitization. For example, if the content of biomass sugar is too low, the final material will have more defects and poor overall performance. If the content of biomass sugar is too high, some biomass sugar will not dissolve, thus preventing it from being fully incorporated into the gel system. This will not only result in a lower degree of graphitization but also adversely affect the performance of the final material. Similarly, if the content of crosslinking agent is too low, the degree of crosslinking in the gel will be low, making it prone to collapse during subsequent carbonization or graphitization. If the content of crosslinking agent is too high, the network of the gel system will be too dense, restricting the migration of biomass sugar during carbonization or graphitization and making it prone to cracking during high-temperature carbonization or graphitization, resulting in poor mechanical properties of the graphitized carbon material.

[0042] It should be noted that, considering that glucose generally contains one water molecule, in the embodiments of the present invention, the biomass sugar in the above proportion refers to the glucose content in glucose monohydrate.

[0043] According to some preferred embodiments, the mass concentration of the catalyst solution is 1-15% (e.g., it can be 1%, 2%, 3%, 5%, 8%, 10%, 12% or 15%), and the mass ratio of the catalyst solution to biomass sugar is 1.6:(80-100) (e.g., it can be 1.6:80, 1.6:85, 1.6:90, 1.6:95 or 1.6:100).

[0044] In this embodiment of the invention, ferric nitrate catalyst is introduced into a gel system of biomass sugar, acrylamide, and a crosslinking agent in solution form. Compared to powdered iron catalyst, the ferric nitrate solution has better dispersibility and can catalyze the degradation and carbonization of biomass sugar to generate biomass carbon precursors at the atomic level. Subsequently, the catalyst solution gradually transforms into metal particles coated within the biomass carbon precursors. During the high-temperature graphitization process at 1200-1500℃, some metal particles initially settle on the biomass carbon precursors and are continuously encapsulated and nucleated by amorphous carbon, undergoing catalytic graphitization. Afterward, the metal particles... The combined effect of the adhesion between carbon and graphite causes metal particles to break through the core and continue to move towards the amorphous carbon side for catalytic graphitization. The other part of the metal particles undergoes catalytic graphitization according to the carbide decomposition mechanism. Furthermore, nitrate ions in the catalyst solution can co-catalyze the graphitization of carbon precursors with metal ions. In this way, the activation energy required for the graphitization of biomass sugar is significantly reduced. Thus, with only a small amount of catalyst solution, a regular graphite crystal structure can be prepared at a relatively low temperature (1200-1500℃), and the final graphitized carbon material has good mechanical and electrical properties.

[0045] Meanwhile, in this embodiment of the invention, by preparing a catalyst aqueous solution of the above-mentioned concentration using a metal catalyst, and then introducing the catalyst aqueous solution into the reaction system in a certain proportion, not only can efficient gel solidification and efficient graphitization of biomass sugar be achieved simultaneously, but also, because the content of catalyst metal particles introduced is extremely small, the excellent mechanical properties of the final graphitized carbon material can be guaranteed to the greatest extent. Furthermore, no subsequent catalyst removal is required. Experiments in this invention have shown that if the concentration of the catalyst solution is too high, and the introduced content is too high, it is not only detrimental to the full dispersion of the catalyst solution in the gel system to achieve efficient graphitization of biomass sugar, but also adversely affects the mechanical properties of the final graphitized carbon material. Conversely, if the concentration of the catalyst solution is too low, and the introduced content is too low, it is not only detrimental to achieving an efficient graphitization process, but also detrimental to ensuring a good degree of graphitization of the final graphitized carbon material, similarly adversely affecting the material's performance.

[0046] According to some preferred embodiments, in step (2), the mass ratio of the crosslinking agent to the initiator is 1:(0.25-0.75) (for example, it can be 1:0.25, 1:0.30, 1:0.35, 1:0.37, 1:0.40, 1:0.45, 1:0.50, 1:0.55, 1:0.60, 1:0.65, 0.70 or 1:0.75).

[0047] In this embodiment of the invention, a certain amount of α-ketoglutaric acid is used as an initiator. The addition of α-ketoglutaric acid can not only initiate gel solidification, but also reduce the ferric ions in the catalyst solution to ferrous ions, thereby better catalyzing the graphitization process of biomass sugar. If the content of the initiator is too high, it will not be conducive to ensuring a high conversion efficiency of biomass sugar. Furthermore, compared with traditional methods such as thermal curing, the use of ultraviolet light curing in this embodiment of the invention can avoid adverse effects on the catalytic performance of the catalyst solution, thereby ensuring better subsequent catalytic efficiency.

[0048] According to some preferred embodiments, in step (1), the temperature for stirring and mixing is 40-50℃ (for example, it can be 40℃, 45℃ or 50℃), and the stirring time is 15-20min (for example, it can be 15min, 18min or 20min); in step (2), the curing time under ultraviolet light is 1-2min (for example, it can be 1min, 1.5min or 2min).

[0049] According to some preferred embodiments, after obtaining the mixed reaction solution in step (1), the steps of sonicating and centrifuging the mixed reaction solution are further included.

[0050] During the preparation of the mixed reaction solution, bubbles are inevitably generated during the stirring process. Therefore, in this embodiment of the invention, after the mixed reaction solution is prepared, it is further subjected to ultrasonication and centrifugation to remove bubbles, thereby preventing a large number of defects inside the graphitized carbon material due to bubbles during the gel solidification process.

[0051] According to some preferred embodiments, in step (3), the pre-carbonization temperature is 25-200℃ (e.g., 25℃, 50℃, 80℃, 100℃, 150℃, 180℃, or 200℃), and the time is 50-55h (e.g., 50h, 51h, 52h, 53h, 54h, or 55h); the carbonization temperature is 700-800℃ (e.g., 700℃, 720℃, 750℃, 780℃, or 800℃), and the time is 1.5-2.5h (e.g., 1.5h, 2h, or 3h); the graphitization is divided into a first heating stage. The heating process consists of a first heating stage and a second heating stage. The heating rate of the first heating stage is 4-5℃ / min (e.g., 4℃ / min, 4.5℃ / min, or 5℃ / min), and the heating temperature is 1000℃. The heating rate of the second heating stage is 3-4℃ / min (e.g., 3℃ / min, 3.5℃ / min, or 4℃ / min), and the heating temperature is 1200-1500℃ (e.g., 1200℃, 1300℃, 1400℃, or 1500℃). The holding time is 1.5-2.5h (e.g., 1.5h, 2h, or 3h).

[0052] In this embodiment of the invention, after obtaining the gel reaction product, it is first placed in an oven for pre-carbonization to remove moisture, low-molecular-weight organic matter, and volatile gases from the gel reaction product, avoiding material cracking or structural collapse due to rapid gas release during subsequent high-temperature treatment. Afterward, it is cooled to room temperature, removed, washed with deionized water, and wiped clean. It is then wrapped in graphite paper and placed in a tube furnace for sequential carbonization and graphitization treatments. Under high-temperature conditions, the dopant (iron ions) first reacts with the carbon matrix (biomass sugar) to generate corresponding carbides. When the temperature continues to rise to the carbide decomposition temperature, the carbides decompose to generate elemental dopant and carbon. This carbon produced by the decomposition of carbides has a good graphite structure, and the elemental dopant formed by decomposition diffuses along the surface of the carbide particles to the disordered carbon side, continuing to react with the disordered carbon to generate carbides while consuming the disordered carbon. As the carbide particles migrate, this process repeats cyclically, thereby catalyzing graphitization and transforming disordered carbon into a graphite crystal structure.

[0053] The present invention also provides a graphitized carbon material, which is prepared by any of the preparation methods described above.

[0054] In summary, this invention utilizes naturally recyclable biomass sugar as the carbon source and ferric nitrate solution as a catalyst, introducing it into an acrylamide gel system. High-temperature heating allows the ferric nitrate solution to catalyze the degradation and carbonization of biomass sugar at the atomic level, generating carbon precursors. Subsequently, iron ions in the ferric nitrate solution gradually transform into metallic iron particles that coat the carbon precursors. Following this, a high-temperature treatment at 1200-1500℃ further catalyzes the formation of graphitized carbon materials from the carbon precursors. Thus, a highly efficient, green, and economical route for preparing graphitized carbon materials is achieved, with a preparation cost only 1 / 10 that of traditional graphite materials, providing an opportunity to improve the sustainability and overall economic efficiency of bio-based graphite material production. Furthermore, experiments conducted according to this invention have demonstrated that the graphitized carbon material prepared at 1400℃ achieves a graphitization degree of up to 80%, and exhibits a hardness of 5.236 GPa and a Young's modulus of 29.546 GPa, demonstrating excellent mechanical properties.

[0055] To more clearly illustrate the technical solution and advantages of the present invention, the following embodiments provide a detailed description of a method for preparing graphitized carbon materials using biomass sugar-derived carbon; wherein, in the following embodiments, the molecular weight of glucose monohydrate is 198 and the molecular weight of glucose is 180.

[0056] Example 1:

[0057] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of catalyst solution (ferric nitrate solution) with a concentration of 15% to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0058] (2) Add 0.26g of initiator (α-ketoglutarate) to the mixed reaction solution, and add the solution to the mold and cure it under UV light for 1 min. After the curing process is over, take out the gel reaction product and put it into a petri dish.

[0059] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 1400°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0060] Example 2:

[0061] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of 10% catalyst solution (ferric nitrate solution) to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0062] (2) Add 0.26g of initiator (α-ketoglutarate) to the mixed reaction solution, and add the solution to the mold and cure it under UV light for 1 min. After the curing process is over, take out the gel reaction product and put it into a petri dish.

[0063] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 1400°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0064] Example 3:

[0065] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of 5% catalyst solution (ferric nitrate solution) to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0066] (2) Add 0.26g of initiator (α-ketoglutarate) to the mixed reaction solution, and add the solution to the mold and cure it under UV light for 1 min. After the curing process is over, take out the gel reaction product and put it into a petri dish.

[0067] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 1400°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0068] Example 4:

[0069] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of 2% catalyst solution (ferric nitrate solution) to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0070] (2) Add 0.26g of initiator (α-ketoglutarate) to the mixed reaction solution, and add the solution to the mold and cure it under UV light for 1 min. After the curing process is over, take out the gel reaction product and put it into a petri dish.

[0071] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 1400°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0072] Example 5:

[0073] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of catalyst solution (ferric nitrate solution) with a concentration of 1% to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0074] (2) Add 0.26g of initiator (α-ketoglutarate) to the mixed reaction solution, and add the solution to the mold and cure it under UV light for 1 min. After the curing process is over, take out the gel reaction product and put it into a petri dish.

[0075] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 1400°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0076] Example 6

[0077] Example 6 is basically the same as Example 1, except that in step (1), 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) is added to 23g of deionized water and magnetically stirred at 45°C for 15min until the solution is clear. Then, 50g of biomass sugar (glucose monohydrate) is added to the solution until it is completely clear, and then 14g of acrylamide is added. Finally, 1.6g of catalyst solution (ferric nitrate solution) with a concentration of 1% is added to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0078] Example 7

[0079] Example 7 is basically the same as Example 1, except that in step (1), 1.4g of crosslinking agent (N,N-dimethylbisacrylamide) is added to 28g of deionized water and magnetically stirred at 45°C for 15min until the solution is clear. Then, 77g of biomass sugar (glucose monohydrate) is added to the solution until it is completely clear, and then 14g of acrylamide is added. Finally, 1.6g of catalyst solution (ferric nitrate solution) with a concentration of 1% is added to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0080] Example 8

[0081] Example 8 is basically the same as Example 1, except that in step (1), the content of the catalyst solution is 3g and the concentration is 10%.

[0082] Example 9

[0083] Example 9 is basically the same as Example 1, except that in step (1), the content of the catalyst solution is 1g and the concentration is 5%.

[0084] Example 10

[0085] Example 10 is basically the same as Example 1, except that in step (1), the catalyst solution is replaced with a cobalt nitrate solution of the same mass and concentration.

[0086] Comparative Example 1

[0087] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of iron powder to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0088] (2) Add 0.26g of initiator (α-ketoglutaric acid) to the mixed reaction solution, and add the solution to the mold and cure it under UV light for min. After the curing process is over, take out the gel reaction product and put it into a petri dish.

[0089] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150℃ for 52h. After the oven cooled to room temperature (25℃), the solid product was removed, washed and wiped clean with deionized water, then wrapped in graphite paper and placed in a tube furnace for carbonization at 750℃ for 2h. After the tube furnace cooled to room temperature (25℃), the product was removed, washed and wiped clean with deionized water, wrapped in graphite paper, and placed in a tube furnace. The temperature was first increased to 1000℃ at a rate of 5℃ / min, then increased to 1400℃ at a rate of 3℃ / min and held for 2h, and then increased to 2500℃ at a rate of 3℃ / min and held for 2h. After graphitization, the product was cooled, washed, dried, and the resulting black blocky sample was the graphitized carbon material.

[0090] Comparative Example 2

[0091] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water, and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear, then add 14g of acrylamide, and finally add 1.6g of catalyst solution (ferric nitrate solution) with a concentration of 15% to obtain a mixed reaction solution. The mixed reaction solution is then sonicated and centrifuged for later use.

[0092] (2) Add 2g of 10% azobisisobutyramidine hydrochloride aqueous solution to the mixed reaction solution and react at 70℃ for 5min to obtain the gel reaction product. Take out the gel reaction product and put it into a petri dish.

[0093] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 1400°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0094] Comparative Example 3

[0095] (1) Add 0.7g of crosslinking agent (N,N-dimethylbisacrylamide) to 23g of deionized water and stir magnetically at 45℃ for 15min until the solution is clear. Then add 77g of biomass sugar (glucose monohydrate) to the solution until it is completely clear. Then add 14g of acrylamide to obtain a mixed reaction solution. Sonicate and centrifuge the mixed reaction solution for later use.

[0096] (2) While stirring, add 1g of 50% triethanolamine aqueous solution and 3g of 10% ammonium persulfate aqueous solution to the mixed reaction solution, and add the solution into the mold and let it stand for 4 minutes. After the reaction, take out the gel reaction product and put it into a petri dish.

[0097] (3) The gel reaction product was transferred to an oven and pre-carbonized at 150°C for 52 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper and placed in a tube furnace. First, the temperature was increased to 1000°C at a heating rate of 5°C / min, and then increased to 2500°C at a heating rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the product was cooled, washed, dried and the resulting black block sample was the graphitized carbon material.

[0098] Comparative Example 4

[0099] (1) Dissolve 1g of catalyst (ferric nitrate) in 30mL of distilled water, then add 2g of carbon source (polypropylene) to it, and stir magnetically for 5 minutes at room temperature to obtain a mixed reaction solution;

[0100] (2) The mixed reaction solution was transferred to a hydrothermal reactor and then to an oven. It was pre-carbonized at 150°C for 12 hours. After the oven cooled to room temperature (25°C), the solid product was taken out, washed and wiped clean with deionized water, and then dried in an 80°C oven for 10 hours. The dried solid product was then ground into powder to obtain a carbon precursor. The carbon precursor was wrapped in graphite paper and placed in a tube furnace for carbonization at 750°C for 2 hours. After the tube furnace cooled to room temperature (25°C), it was taken out, washed and wiped clean with deionized water, wrapped in graphite paper, and placed in a tube furnace. The temperature was first increased to 1000°C at a rate of 5°C / min, and then increased to 1400°C at a rate of 3°C / min and held for 2 hours. After the catalytic graphitization was completed, the temperature was lowered, washed, dried, and the resulting black block sample was the graphitized carbon material.

[0101] The graphitized carbon materials in Examples 1 to 10 and Comparisons 1 to 4 were subjected to performance tests, and the test results are shown in Table 1.

[0102] Hardness and Young's modulus tests were conducted according to the methods in GB / T 22458-2008 General Rules for Instrumented Nanoindentation Tests; Graphitization degree: The materials prepared in the above examples were subjected to XRD tests, and the graphitization degree was calculated based on the test results.

[0103] Table 1

[0104] Example 1 3.473 20.779 85％ Example 2 3.525 21.451 75％ Example 3 3.823 22.677 67％ Example 4 5.288 29.063 45％ Example 5 5.236 29.546 23％ Example 6 2.750 17.443 66％ Example 7 3.118 19.712 57％ Example 8 3.186 19.588 88％ Example 9 5.222 29.446 22％ Example 10 5.210 29.813 -- Comparative Example 1 2.101 12.119 50％ Comparative Example 2 2.753 17.443 67％ Comparative Example 3 3.118 19.178 57％ Comparative Example 4 1.348 6.221 67％

[0105] In this context, "--" indicates that graphitization is not possible;

[0106] Depend on Figure 1 The XRD image of the graphitized carbon material shows a peak value of 26.4. According to the Franklin equation, the graphitization degree in Example 1 of this invention is as high as 85%. Furthermore, combined with... Figure 2 and Figure 3 The SEM images show that the graphitized carbon material in Example 1 exhibits a relatively regular graphite crystal structure. Through... Figure 4 The Raman spectra show that I D / I G The value is approximately 0.095, indicating a high degree of graphitization in the graphitized carbon material. Further testing of the mechanical properties of the graphitized carbon material at five points revealed... Figure 5 and Figure 6As can be seen from the table, the graphitized carbon material in the embodiments of the present invention exhibits high hardness and Young's modulus, and has good mechanical strength. Furthermore, as shown in Table 1, in these embodiments, glucose is used as the carbon source, and ferric nitrate is used as the catalyst. Introducing it into the gel system and employing high-temperature heating, only 0.8% of the catalyst is added to the biomass sugar system, enabling the catalyst to catalyze the degradation and carbonization of glucose at the atomic level to generate carbon precursors. This achieves a highly efficient and green route for glucose degradation. Using this as raw material, graphitized carbon material with a graphitization degree of over 80% is prepared at 1400℃. This material has a hardness of 5.236 GPa and a Young's modulus of 29.546 GPa, demonstrating excellent mechanical properties. In Example 10, if the catalyst solution is replaced with the same mass and concentration of cobalt nitrate solution, although the prepared carbon material has good mechanical properties, graphitization cannot be achieved at a low temperature of 1400℃. In Comparative Example 1, replacing the catalyst with the same mass of iron powder not only reduces the graphitization degree and mechanical properties of the graphitized carbon material, but also significantly increases the graphitization temperature in the later stages. In Comparative Example 2, changing the initiator and using thermosetting for gel curing reduces the catalytic effect of the catalyst solution, thus decreasing the final graphitization degree and mechanical properties of the graphitized carbon material. In Comparative Example 3, without adding a catalyst solution, simply gelling biomass sugar with acrylamide and then performing pre-carbonization, carbonization, and graphitization significantly increases the graphitization temperature and decreases the graphitization degree (from...). Figure 7 The Raman spectrum shows that I D / I G The graphite content is approximately 1.636, indicating a poor degree of graphitization. In Comparative Example 4, if the green and recyclable biomass sugar is replaced with the commonly used high-molecular organic polypropylene and catalyzed with up to 50% ferric nitrate, not only may structural collapse or foaming occur during the high-temperature graphitization process, but the resulting graphitized carbon material also has poor mechanical properties.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing graphitized carbon materials using biomass sugar-derived carbon, characterized in that, The method includes the following steps: (1) Add the crosslinking agent to water and stir until well mixed. Then add biomass sugar, acrylamide and catalyst solution in sequence and stir until well mixed to obtain a mixed reaction solution. The catalyst solution is a solution containing metal ions and nitrate ions. The catalyst solution is a ferric nitrate solution. The mass ratio of crosslinking agent, acrylamide, biomass sugar and water is 1:(20-30):(80-100):(40-45). The mass concentration of the catalyst solution is 1-15%. The mass ratio of the catalyst solution to biomass sugar is 1.6:(80-100). (2) Add an initiator to the mixed reaction solution and cure it under ultraviolet light to obtain a gel reaction product; the initiator is α-ketoglutaric acid; the mass ratio of the crosslinking agent to the initiator is 1:(0.25-0.75). (3) The gel reaction product is subjected to pre-carbonization, carbonization and graphitization treatment in sequence to obtain the graphitized carbon material; the graphitization is divided into a first heating stage and a second heating stage; wherein, the heating rate of the first heating stage is 4-5℃ / min, the heating temperature is 1000℃, the heating rate of the second heating stage is 3-4℃ / min, the heating temperature is 1200-1500℃, and the holding time is 1.5-2.5h; the graphitization degree of the graphitized carbon material is as high as 80% or more.

2. The method according to claim 1, characterized in that, In step (1), the crosslinking agent is N,N'-dimethylbisacrylamide, and the biomass sugar is either glucose or sucrose.

3. The method according to claim 1, characterized in that, In step (1), the mixing temperature is 40-50℃, and the mixing time is 15-20 min; and / or In step (2), the UV lamp irradiation curing time is 1-2 minutes.

4. The method according to claim 1, characterized in that, In step (1), after obtaining the mixed reaction solution, the steps of sonicating and centrifuging the mixed reaction solution are also included.

5. The method according to claim 1, characterized in that, In step (3), the pre-carbonization temperature is 25-200℃ and the time is 50-55h.

6. The method according to claim 1, characterized in that, In step (3), the carbonization temperature is 700-800℃ and the time is 1.5-2.5h.

7. A graphitized carbon material, characterized in that, It is prepared by any one of claims 1 to 6.

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