Preparation method of porous graphite and material for preparing porous graphite
By modifying the resin base liquid of water-soluble cellulose and polystyrene microspheres, drying, carbonizing and graphitization treatment methods, the existing porous graphite preparation process has solved the problems of high energy consumption, serious pollution and high product ash content, and achieved high purity and high strength porous graphite preparation, and the process is safe and environmentally friendly.
Patent Information
- Application Number
- CN202411627255.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-02-28
AI Technical Summary
The existing porous graphite preparation process has a long cycle, high energy consumption and serious pollution, and the porous graphite ash and volatile components obtained are relatively high, and it needs to be purified multiple times to meet the demand.
Modified water-soluble cellulose and polystyrene microspheres are used as the main components of the resin base liquid, and they are stirred evenly in deionized water, and porous graphite is prepared after drying, carbonization and graphitization.
The high purity, low ash and low volatile components of porous graphite are achieved, with high strength and no need for multiple purifications, which reduces production costs, increases the application scale of the product, and is safe and environmentally friendly.
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Figure CN119528575A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of carbon materials, and relates to a method for preparing porous graphite and a material for preparing the porous graphite. Background Art
[0002] Porous graphite is widely used in the fields of third-generation semiconductor manufacturing, petrochemicals, organic synthesis, lithium batteries and fuel cells. At the same time, porous graphite is also the matrix for preparing other porous materials. Other porous materials, such as porous ceramics and porous metals, can be prepared by preparing porous graphite. Porous ceramic materials are widely used in semiconductors, aerospace, chemical engineering and construction engineering; porous metals are mostly used in orthopedics, dental implants, fuel cells, aerospace and chemical engineering.
[0004] Most porous graphites are prepared through the foaming, carbonization and graphitization of special asphalt. The preparation process is long, energy-intensive and highly polluting. The ash and volatile matter of the prepared porous graphite are relatively high, and it needs to go through purification and other processes to meet the needs. The entire preparation process also consumes a lot of electricity and uses more toxic and harmful chemicals, which seriously pollutes the natural environment. Summary of the invention
[0005] The present disclosure provides a method for preparing porous graphite and a material for preparing porous graphite, which can effectively solve the above problems.
[0006] The present disclosure is implemented as follows:
[0007] In one aspect, the present disclosure provides a method for preparing a porous graphite substrate, the method comprising:
[0008] The method comprises:
[0009] Adding modified water-soluble cellulose and a dispersant to deionized water, stirring evenly at 55-100° C. to obtain a resin base liquid; the viscosity of the resin base liquid is 110-140 cps;
[0010] Adding polystyrene microspheres to the resin base liquid and stirring the mixture to obtain a mixed liquid;
[0011] The mixed solution is poured into a mold, and then placed in an oven and dried at 90-120° C., and the mold is removed to obtain a resin;
[0012] The resin is placed in a carbonization furnace, subjected to carbonization treatment under a protective gas atmosphere, and naturally cooled to room temperature to obtain a porous graphite substrate.
[0013] In another aspect, the present disclosure provides a method for preparing porous graphite, the method comprising:
[0014] The porous graphite substrate prepared by the above method is repeatedly impregnated and carbonized with a resin-based liquid until a predetermined density is reached to obtain a densified substrate;
[0015] The densified substrate is placed in a high-temperature furnace and graphitized at 2500-2600° C. to obtain porous graphite.
[0016] On the other hand, the present disclosure provides a material for preparing a porous graphite substrate or porous graphite, the material comprising a resin base liquid and polystyrene microspheres; the resin base liquid comprises modified water-soluble cellulose, a dispersant and deionized water; the viscosity of the resin base liquid is 110-140 cps.
[0017] The beneficial effects of the present disclosure are:
[0018] The present disclosure provides a method for preparing porous graphite. The carbon source in the resin-based liquid used is modified water-soluble cellulose, which has a simple composition and avoids the introduction of new impurity elements. Therefore, it can ensure that the prepared porous graphite has high purity, extremely low ash content and volatile matter, and high strength. It can well meet the use needs of various industries without multiple purifications, expand the application scale of the product, and reduce production costs.
[0019] The solvent in the resin base liquid is deionized water, and there is no need to use flammable organic solvents. The entire preparation process does not require the use of hazardous materials, has a high safety factor, and is environmentally friendly.
[0020] The method for preparing porous graphite uses a polystyrene microsphere material with a high density, which can be effectively dispersed in the resin base liquid without sedimentation, and helps the porous graphite substrate to form a porous structure after the polystyrene volatilizes during carbonization treatment, thereby ensuring that the prepared porous graphite has a high porosity. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.
[0022] Figure 1 This is a microscopic photograph of the carbon skeleton after carbonization treatment in Example 1 of the present disclosure.
[0023] Figure 2 This is a micrograph of the porous graphite prepared in Example 1 of the present disclosure.
[0024] Figure 3 This is a photo of the porous graphite prepared in Example 2 of the present disclosure. DETAILED DESCRIPTION
[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure for protection, but merely represents the selected embodiments of the present disclosure. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.
[0026] The present disclosure provides a method for preparing a porous graphite substrate, the method comprising:
[0027] Modified water-soluble cellulose and a dispersant are added to deionized water, and stirred evenly at 55-100° C. to obtain a resin base liquid; the viscosity of the resin base liquid is 110-140 cps.
[0028] Modified cellulose is an organic polymer material with the advantages of good film-forming properties, non-toxicity, natural degradation, and no need for other additives. It will not produce harmful substances during the sintering process. During the carbonization process, high-temperature decomposition occurs, and the residual carbon obtained constitutes a carbon skeleton to support the porous structure of the substrate.
[0029] The surface tension of the resin base liquid can be adjusted by adjusting the viscosity of the resin base liquid to ensure the wetting effect of the resin base liquid on the polystyrene microspheres.
[0030] In some embodiments, the modified water-soluble cellulose includes at least one of hydroxypropyl methylcellulose, water-soluble cellulose acetate, and hydroxyethyl cellulose.
[0031] When using different types of modified water-soluble cellulose, the concentration of the modified water-soluble fiber in the resin base liquid also needs to be adjusted accordingly to meet the viscosity requirements.
[0032] In some embodiments, the modified water-soluble cellulose is hydroxypropyl methylcellulose, and the viscosity of the hydroxypropyl methylcellulose is 100000-200000 mPa.s. Hydroxypropyl methylcellulose with this viscosity parameter can be well dissolved to form a resin base liquid, and the material cost can be controlled.
[0033] In some embodiments, the dispersant is polyethylene glycol, and the molecular weight of the polyethylene glycol is 200-400.
[0034] Polyethylene glycol with this molecular weight can act as a dispersant and is beneficial to the dispersion effect of polystyrene microspheres in the resin base liquid.
[0035] Using polyethylene glycol dispersant, the resin base liquid has a simple composition, only carbon, hydrogen, and oxygen, and no other elements are introduced. Therefore, the ash and volatile matter in the obtained porous graphite are extremely low and the purity is high.
[0036] In some embodiments, further, the mass ratio of the dispersant to the modified water-soluble cellulose is 10: -5 -10 -4 :1.
[0037] When the amount of dispersant added reaches 0.001% of the mass of the modified water-soluble cellulose, a good dissolution-aiding effect can be achieved, but when it exceeds 0.01% of the mass of the modified water-soluble cellulose, there is no better dissolution-aiding effect.
[0038] Add polystyrene microspheres into the resin base liquid and stir them thoroughly to obtain a mixed liquid.
[0039] Polystyrene microspheres have a high density and can be effectively dispersed in the resin base liquid without settling. During the carbonization process, polystyrene evaporates, leaving cavities inside the substrate to form a porous structure.
[0040] In some embodiments, the diameter of the polystyrene microspheres is 0.05-5 mm, thereby controlling the size of the cavities in the substrate, so that the prepared porous graphite has a more uniform pore size, higher strength and porosity.
[0041] The mixed liquid is poured into a mold, and then placed in an oven to dry at 90-120° C., and the mold is removed to obtain a resin.
[0042] The mold size can be determined according to the product size.
[0043] The resin is placed in a carbonization furnace, subjected to carbonization treatment under a protective gas atmosphere, and naturally cooled to room temperature to obtain a porous graphite substrate.
[0044] In some embodiments, the carbonization process comprises:
[0045] The temperature was raised to 400°C at a rate of 20°C / h and kept at that temperature for 2 hours to promote the decomposition of polystyrene, leaving a cavity for further formation of the carbon skeleton.
[0046] Then continue to heat up to 950-1050°C at a heating rate of 30°C / h and keep warm for 1 hour. The modified cellulose is further decomposed at high temperature to form a carbon skeleton to support the porous structure substrate.
[0047] The thermal conductivity of resin materials is poor, and the heating rate of the entire carbonization process should not be too high, so as to prevent the gas generated in the process from being discharged in time and destroying the carbon skeleton.
[0048] In some embodiments, the protective gas is a noble gas that does not chemically react with reactants.
[0049] In some embodiments, the protective gas is argon or neon, or a mixture of both.
[0050] The present disclosure provides a method for preparing porous graphite, the method comprising:
[0051] The porous graphite substrate prepared by the method of any of the above embodiments is repeatedly impregnated and carbonized with the resin-based liquid until the desired density is reached to obtain a densified substrate.
[0052] The porous graphite substrate has too high a porosity and lacks strength, so further densification treatment is required, specifically, repeated "impregnation-carbonization".
[0053] In some embodiments, the predetermined density is 1.0-1.2 g / cm 3 .
[0054] The substrate at this density can ensure that the porosity after graphitization is still higher than that of porous graphite products on the market.
[0055] The densified substrate is placed in a high-temperature furnace and graphitized at 2500-2600° C. to obtain porous graphite.
[0056] The pore size of the porous graphite products prepared by the traditional process is uneven and the impurity content is high, and it needs to be purified multiple times before it can be used. The preparation method disclosed in the present invention is simple to operate, convenient and fast, low in cost, and the finished product has high purity and high strength, which is suitable for rapid large-scale industrialization.
[0057] Moreover, compared with the traditional foamed asphalt method, the preparation method disclosed in the present invention greatly alleviates the serious environmental pollution and huge energy consumption of the porous graphite industry. In addition, since no harmful substances are used or generated in the entire production process, it conforms to the current low-carbon and environmentally friendly concept, will not cause damage to operators and the natural environment, and is more easily accepted by the general public.
[0058] Example 1
[0059] The present disclosure provides a method for preparing porous graphite, comprising the following steps:
[0060] Prepare the resin base liquid: Mix hydroxypropyl methylcellulose with hot water above 55°C, add polyethylene glycol 200 and stir evenly, and continue to add hot water to dilute to the required viscosity.
[0061] The viscosity of the hydroxypropyl methylcellulose used is 200000 mPa.s.
[0062] The added amount of polyethylene glycol 200 is 0.001% of the mass of hydroxypropyl methylcellulose.
[0063] Hydroxypropyl methylcellulose can be maintained in a dissolved state by heating in a water bath.
[0064] The viscosity of the resin base liquid after configuration is 110cps.
[0065] Pour polystyrene microspheres into the resin base liquid, shake and stir thoroughly, so that the liquid surface just immerses the microspheres. After mixing evenly, pour the mixture into the mold, and brush the inner surface of the mold with refined paraffin in advance. Put the mold into the oven and dry it at 105℃ for 2h.
[0066] Wherein, the microspheres are transparent polystyrene plastic microspheres with a diameter of 0.05 mm.
[0067] Remove the mold and take out the dried resin. Put the resin into the carbonization furnace, evacuate it, fill it with high-purity argon gas to normal pressure, heat it to 400℃ at a rate of 20℃ / h, keep it warm for 2h; then continue to heat it to 1000℃ at a rate of 30℃ / h, keep it warm for 1h, and then cool it down naturally to room temperature to obtain a porous graphite substrate. Use metallographic observation, such as Figure 1 As shown, the porous graphite substrate has a high porosity and a relatively uniform pore size of about 27.16 μm.
[0068] Among them, the purity of high-purity argon is 99.999%.
[0069] The porous graphite substrate is repeatedly impregnated and carbonized with a resin-based liquid until the density reaches 1.2 g / cm 3 .
[0070] After carbonization, the densified substrate is placed in a high-temperature furnace and graphitized at 2600°C to obtain porous graphite.
[0071] Use metallographic observation, such as Figure 2 As shown, the pore size of porous graphite is relatively uniform, about 10-15μm, and the surface is smooth and free of impurities. After weighing and measuring, the density is 1.15 / cm 3After inspection, it was shown that the ash content was 7ppm, which met the design index requirements of the product.
[0072] The existing products on the market have visible particle falling phenomenon when touched. The porous graphite prepared in the embodiment of the present disclosure does not have this phenomenon, which indicates that it has higher strength.
[0073] Example 2
[0074] The present disclosure provides a method for preparing porous graphite, comprising the following steps:
[0075] Prepare the resin base liquid: Mix water-soluble cellulose acetate (brand: Eastman, model: CAB-553-0.4) with hot water above 55°C, add polyethylene glycol 400 and stir evenly, and continue to add hot water to dilute to the required viscosity.
[0076] The added amount of polyethylene glycol 400 is 0.01% of the water-soluble cellulose acetate.
[0077] The viscosity of the resin base liquid after configuration is 140cps.
[0078] Pour polystyrene microspheres into the resin base liquid, shake and stir thoroughly, so that the liquid surface just immerses the microspheres. After mixing evenly, pour the mixture into the mold, and brush the inner surface of the mold with refined paraffin in advance. Put the mold into the oven and dry it at 105℃ for 2h.
[0079] Wherein, the microspheres are transparent polystyrene plastic microspheres with a diameter of 5 mm.
[0080] The mold was removed, and the dried resin was taken out. The resin was placed in a carbonization furnace, and after vacuuming, high-purity argon was filled to normal pressure, and the temperature was raised to 400°C at a heating rate of 20°C / h, and kept at that temperature for 2h; then the temperature was continued to be raised to 1050°C at a heating rate of 30°C / h, and kept at that temperature for 1h, and then naturally cooled to room temperature to obtain a porous graphite substrate.
[0081] Among them, the purity of high-purity argon is 99.999%.
[0082] The porous graphite substrate is repeatedly impregnated and carbonized with a resin-based liquid until the density reaches 1.0 g / cm 3 .
[0083] After carbonization, the densified substrate is placed in a high-temperature furnace and graphitized at 2500°C to obtain porous graphite.
[0084] The prepared porous graphite was observed visually, such as Figure 3As shown, the porous structure is clearly visible to the naked eye. After the diameter of the polystyrene microspheres is increased, the pores are correspondingly enlarged. The method provided by the present disclosure can conveniently and quickly prepare porous graphite of a desired size.
[0085] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.
Claims
1. A method for preparing a porous graphite substrate, characterized in that: The method comprises: Adding modified water-soluble cellulose and a dispersant to deionized water, stirring evenly at 55-100° C. to obtain a resin base liquid; the viscosity of the resin base liquid is 110-140 cps; Adding polystyrene microspheres into the resin base liquid and stirring the mixture sufficiently to obtain a mixed liquid; The mixed solution is poured into a mold, and then placed in an oven and dried at 90-120° C., and the mold is removed to obtain a resin; The resin is placed in a carbonization furnace, subjected to carbonization treatment under a protective gas atmosphere, and naturally cooled to room temperature to obtain a porous graphite substrate.
2. The preparation method according to claim 1, characterized in that The modified water-soluble cellulose includes at least one of hydroxypropyl methylcellulose, water-soluble cellulose acetate and hydroxyethyl cellulose.
3. The preparation method according to claim 2, characterized in that: The modified water-soluble cellulose is hydroxypropyl methylcellulose, and the viscosity of the hydroxypropyl methylcellulose is 100000-200000 mPa.s.
4. The preparation method according to claim 1, characterized in that: The dispersant is polyethylene glycol, and the molecular weight of the polyethylene glycol is 200-400.
5. The preparation method according to claim 1, characterized in that: The mass ratio of the dispersant to the modified water-soluble cellulose is 10 -5 -10 -4 :
1.
6. The preparation method according to claim 1, characterized in that: The diameter of the polystyrene microspheres is 0.05-5 mm.
7. The preparation method according to claim 1, characterized in that: The carbonization treatment comprises: Heat up to 400°C at a rate of 20°C / h and keep warm for 2 hours; Then continue to heat up to 950-1050°C at a heating rate of 30°C / h and keep warm for 1 hour.
8. A method for preparing a porous graphite substrate, characterized in that: The method comprises: The porous graphite substrate prepared by the method according to any one of claims 1 to 7 is repeatedly impregnated and carbonized with the resin-based liquid until a predetermined density is reached to obtain a densified substrate; The densified substrate is placed in a high-temperature furnace and graphitized at 2500-2600° C. to obtain porous graphite.
9. The preparation method according to claim 8, characterized in that: The predetermined density is 1.0-1.2 g / cm 3 .
10. A material for preparing a porous graphite substrate or porous graphite, characterized in that: The material comprises a resin base liquid and polystyrene microspheres; the resin base liquid comprises modified water-soluble cellulose, a dispersant and deionized water; and the viscosity of the resin base liquid is 110-140 cps.