CN104229787A - Method for increasing yield of graphene prepared by supercritical fluid through pretreatment of natural graphite - Google Patents
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 95
- 229910021389 graphene Inorganic materials 0.000 title claims abstract description 58
- 239000012530 fluid Substances 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 40
- 229910021382 natural graphite Inorganic materials 0.000 title claims abstract description 39
- 239000000463 material Substances 0.000 claims abstract description 56
- 239000002253 acid Substances 0.000 claims abstract description 24
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 17
- 239000010439 graphite Substances 0.000 claims abstract description 17
- 238000003756 stirring Methods 0.000 claims abstract description 16
- 239000002002 slurry Substances 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 10
- 239000000654 additive Substances 0.000 claims abstract description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 25
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 21
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 14
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 13
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 12
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 7
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 6
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- 230000000996 additive effect Effects 0.000 claims description 4
- 229910017604 nitric acid Inorganic materials 0.000 claims description 4
- NJPQAIBZIHNJDO-UHFFFAOYSA-N 1-dodecylpyrrolidin-2-one Chemical compound CCCCCCCCCCCCN1CCCC1=O NJPQAIBZIHNJDO-UHFFFAOYSA-N 0.000 claims description 3
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 3
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 3
- -1 CO 2 Chemical compound 0.000 claims description 2
- 238000001291 vacuum drying Methods 0.000 claims description 2
- 238000002203 pretreatment Methods 0.000 claims 10
- 235000011089 carbon dioxide Nutrition 0.000 claims 1
- 238000004299 exfoliation Methods 0.000 abstract description 8
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 239000007921 spray Substances 0.000 abstract description 3
- 238000001914 filtration Methods 0.000 abstract 1
- 238000009830 intercalation Methods 0.000 description 9
- 230000002687 intercalation Effects 0.000 description 9
- 239000002994 raw material Substances 0.000 description 7
- 229910002092 carbon dioxide Inorganic materials 0.000 description 6
- 239000012265 solid product Substances 0.000 description 6
- 239000001569 carbon dioxide Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 125000000524 functional group Chemical group 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000012263 liquid product Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- WPPOGHDFAVQKLN-UHFFFAOYSA-N N-Octyl-2-pyrrolidone Chemical compound CCCCCCCCN1CCCC1=O WPPOGHDFAVQKLN-UHFFFAOYSA-N 0.000 description 2
- 238000010306 acid treatment Methods 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 238000010907 mechanical stirring Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000035939 shock Effects 0.000 description 2
- OHLUUHNLEMFGTQ-UHFFFAOYSA-N N-methylacetamide Chemical compound CNC(C)=O OHLUUHNLEMFGTQ-UHFFFAOYSA-N 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- LZOZLBFZGFLFBV-UHFFFAOYSA-N sulfene Chemical compound C=S(=O)=O LZOZLBFZGFLFBV-UHFFFAOYSA-N 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
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Abstract
本发明涉及对天然石墨预处理提高超临界流体制备石墨烯产率的方法，将天然石墨粉和酸加入到容器中并搅拌均匀，加入添加剂并降温得到低温的石墨浆料，喷入到盛有超临界流体介质的高压反应釜中进行超临界处理，然后将超临界处理后的物料快速喷入到常压产料罐内，经过滤、分离产料罐内的物料并干燥，得到石墨烯产物。与现有技术相比，本申请将酸预先处理过的低温天然石墨浆料作为进料，与常温天然石墨作为进料相比，通过超临界流体剥离过程，石墨烯的产率提高约为2～5倍，本发明不但提高了石墨烯的产率，而且也保持了石墨烯具有的电性能和热性能。
The invention relates to a method for improving the yield of graphene prepared by supercritical fluid through pretreatment of natural graphite. Add natural graphite powder and acid into a container and stir evenly, add additives and cool down to obtain low-temperature graphite slurry, and spray it into a container containing Supercritical treatment is carried out in a high-pressure reactor with a supercritical fluid medium, and then the supercritically treated material is quickly sprayed into the normal pressure production tank, and the graphene product is obtained by filtering, separating and drying the material in the production tank . Compared with the prior art, this application uses the low-temperature natural graphite slurry that the acid has pre-treated as the feed material, and compared with the normal temperature natural graphite as the feed material, through the supercritical fluid exfoliation process, the productive rate of graphene is increased by about 2 ~5 times, the invention not only improves the yield of graphene, but also maintains the electrical and thermal properties of graphene.
Description
技术领域technical field
本发明属于纳米材料制备技术领域，尤其是涉及对天然石墨预处理提高超临界流体制备石墨烯产率的方法。The invention belongs to the technical field of nanometer material preparation, and in particular relates to a method for improving the yield of graphene prepared by supercritical fluid through pretreatment of natural graphite.
背景技术Background technique
由于石墨烯的独特性能，因而在许多领域具有广泛的应用前景。为了实现石墨烯的商业化应用，最关键问题是要获得大量的高质量石墨烯。目前，出现了许多如何制备石墨烯的方法，如机械剥离法、化学还原法等。通过机械剥离法得到的石墨烯具有优异的电性能，但产率十分低；氧化还原法能够实现石墨烯大规模化生产，然而，得到的石墨烯的电性能不是太理想。超临界流体具有优异的表面湿润能力、低的表面张力、高扩散系数、低黏度系数，这些特性方便了超临界流体插层和剥离石墨，制备出石墨烯。超临界流体剥离天然石墨制备石墨烯过程，是一个纯粹的物理脱落过程，并没有引入其它杂质，因此，得到的石墨烯具有优异的电性能和热性能。但是，石墨烯的产率不是很高。本发明提出将酸微弱处理过的低温天然石墨浆料作为超临界流体剥离的原料，制备石墨烯。该发明大大提高了超临界流体剥离天然石墨制备石墨烯的产率，同时，石墨烯具有很高的电性能。Due to the unique properties of graphene, it has broad application prospects in many fields. In order to realize the commercial application of graphene, the most critical issue is to obtain a large amount of high-quality graphene. At present, there are many methods how to prepare graphene, such as mechanical exfoliation method, chemical reduction method and so on. The graphene obtained by the mechanical exfoliation method has excellent electrical properties, but the yield is very low; the redox method can realize large-scale production of graphene, however, the electrical properties of the obtained graphene are not ideal. Supercritical fluid has excellent surface wetting ability, low surface tension, high diffusion coefficient, and low viscosity coefficient. These characteristics facilitate supercritical fluid intercalation and exfoliation of graphite to prepare graphene. The process of supercritical fluid exfoliating natural graphite to prepare graphene is a purely physical exfoliation process without introducing other impurities. Therefore, the obtained graphene has excellent electrical and thermal properties. However, the yield of graphene is not very high. The invention proposes to use low-temperature natural graphite slurry weakly treated by acid as a raw material for supercritical fluid exfoliation to prepare graphene. The invention greatly improves the yield of graphene prepared by exfoliating natural graphite with supercritical fluid, and graphene has high electrical properties at the same time.
申请号为201210001582.6的中国专利公开了超临界二氧化碳剥离制备大尺度石墨烯的方法，采用超临界CO2为剥离剂，表面活性剂为分散剂，石墨粉和分散剂置于高压釜内，再通入CO2，在超临界的状态下循环流动，之后快速降压至常压，重复上述过程，使物料经历多次升压和降压过程，通过控制升压和降压次数控制石墨烯层数，即制备得到大尺度石墨烯，但是该方法最终获得产品的产率相对较低，这也是本发明着重需要解决技术问题。The Chinese patent application number 201210001582.6 discloses a method for preparing large-scale graphene by exfoliating supercritical carbon dioxide. Supercritical CO2 is used as the stripping agent, and the surfactant is used as the dispersant. The graphite powder and the dispersant are placed in an autoclave, and then passed Inject CO 2 , circulate in a supercritical state, and then rapidly reduce the pressure to normal pressure, repeat the above process, so that the material undergoes multiple boosting and depressurization processes, and control the number of graphene layers by controlling the number of boosting and depressurization , that is, large-scale graphene is prepared, but the yield of the final product obtained by this method is relatively low, which is also an important technical problem to be solved in the present invention.
发明内容Contents of the invention
本发明的目的就是为了克服超临界流体剥离天然石墨制备石墨烯方法中产率不理想的问题，提出了将酸预先微弱处理过的低温天然石墨浆料作为高压反应釜的进料，制备石墨烯，大大提高了石墨烯的产率，同时，石墨烯的本征特性也没有受到损害。The purpose of the present invention is exactly in order to overcome the problem that supercritical fluid exfoliates natural graphite and prepares the problem of unsatisfactory yield in the graphene method, has proposed the low-temperature natural graphite slurry that acid is weakly treated in advance as the feedstock of autoclave, prepares graphene, The yield of graphene is greatly improved, and at the same time, the intrinsic properties of graphene are not damaged.
本发明的目的可以通过以下技术方案来实现：The purpose of the present invention can be achieved through the following technical solutions:
对天然石墨预处理提高超临界流体制备石墨烯产率的方法，采用以下步骤：The method for improving the yield of graphene prepared by supercritical fluid to natural graphite pretreatment adopts the following steps:
(1)将天然石墨粉和酸加入到容器中并搅拌均匀；(1) Join natural graphite powder and acid in the container and stir;
(2)过滤或分离多余的酸，然后在物料中加入添加剂并搅拌均匀；(2) Filter or separate excess acid, then add additives to the material and stir evenly;
(3)将上述物料转移到低温容器中并降温，得到低温的石墨浆料；(3) above-mentioned material is transferred in the cryogenic container and cools down, obtains the graphite slurry of low temperature;
(4)将低温石墨浆料快速喷入到盛有超临界流体介质的高压反应釜中；(4) The low-temperature graphite slurry is quickly sprayed into a high-pressure reactor filled with a supercritical fluid medium;
(5)控制高压反应釜中物料的温度和压力，并使得物料在高压反应釜中停留进行超临界处理；(5) Control the temperature and pressure of the material in the autoclave, and make the material stay in the autoclave for supercritical treatment;
(6)将超临界处理后的物料快速喷入到常压产料罐内；(6) Rapidly spray the supercritically treated material into the normal pressure production tank;
(7)过滤、分离产料罐内的物料并干燥，得到石墨烯产物。(7) Filtrating, separating and drying the material in the product tank to obtain a graphene product.
步骤(1)中天然石墨粉和酸的重量比为1∶10～10∶1，采用的酸为浓度大于70wt％的硫酸、浓度大于65wt％的硝酸或浓度大于37wt％的盐酸，天然石墨粉和酸搅拌处理5～60分钟。The weight ratio of natural graphite powder and acid is 1: 10～10: 1 in the step (1), and the acid that adopts is the sulfuric acid that concentration is greater than 70wt%, the nitric acid that concentration is greater than 65wt% or the hydrochloric acid that concentration is greater than 37wt%, natural graphite powder Stir with acid for 5-60 minutes.
步骤(2)中所述的添加剂为乙二醇或乙醇，添加量为石墨粉重量的0.1～5％。The additive described in the step (2) is ethylene glycol or ethanol, and the added amount is 0.1-5% of the weight of the graphite powder.
步骤(3)中石墨浆料降温至-30～0℃。In step (3), the graphite slurry is cooled to -30-0°C.
步骤(4)中所述的超临界流体介质包括但不限于二氧化碳、乙醇、N-甲基吡咯烷酮、二甲基乙酰胺、1-十二烷基-2-吡咯烷酮、二甲基甲酰胺、二甲亚矾、异丙醇、N-辛基-2-吡咯烷酮、丙酮、四氢呋喃、环己烷或甲醇。The supercritical fluid medium described in step (4) includes but not limited to carbon dioxide, ethanol, N-methylpyrrolidone, dimethylacetamide, 1-dodecyl-2-pyrrolidone, dimethylformamide, di Methylenesulfone, isopropanol, N-octyl-2-pyrrolidone, acetone, tetrahydrofuran, cyclohexane or methanol.
作为优选的实施方式，超临界流体介质可以采用乙醇、CO2、二甲基乙酰胺、四氢呋喃或N-甲基吡咯烷酮。As a preferred embodiment, the supercritical fluid medium can be ethanol, CO 2 , dimethylacetamide, tetrahydrofuran or N-methylpyrrolidone.
步骤(5)中高压反应釜中物料的温度和压力接近超临界流体介质的临界温度和压力，其中温度为30～390℃，压力为2～40MPa，物料在高压反应釜中停留时间为15～120分钟。In the step (5), the temperature and pressure of the material in the autoclave are close to the critical temperature and pressure of the supercritical fluid medium, wherein the temperature is 30 to 390° C., the pressure is 2 to 40 MPa, and the residence time of the material in the autoclave is 15 to 40 MPa. 120 minutes.
其中，采用二氧化碳作为超临界流体介质时，高压反应釜中物料的温度为35℃、压力为7.5Mpa、物料停留时间为60分钟；采用乙醇作为超临界流体介质时，物料温度为245℃、压力为6.5Mpa、停留时间为50分钟；二甲基乙酰胺为超临界流体介质时，物料温度为270℃、压力为6Mpa、停留时间为40分钟。Among them, when carbon dioxide is used as the supercritical fluid medium, the temperature of the material in the autoclave is 35°C, the pressure is 7.5Mpa, and the residence time of the material is 60 minutes; when ethanol is used as the supercritical fluid medium, the temperature of the material is 245°C, the pressure The temperature is 6.5Mpa, and the residence time is 50 minutes; when dimethylacetamide is a supercritical fluid medium, the material temperature is 270°C, the pressure is 6Mpa, and the residence time is 40 minutes.
步骤(7)中采用真空干燥，干燥温度为35～100℃，干燥时间为1～12小时。In step (7), vacuum drying is adopted, the drying temperature is 35-100° C., and the drying time is 1-12 hours.
与现有技术相比，本发明专利的创新内容在于：(1)通过对石墨原料的预处理来提高后续剥离产品的产率；(2)公开了对原料预处理的方法，通过酸处理和低温处理的具体工艺；(3)阐明了预处理为什么能提高产率的原理，具体如下：Compared with the prior art, the innovative content of the patent of the present invention lies in: (1) through the pretreatment of graphite raw materials, the yield of subsequent exfoliated products is improved; (2) a method for pretreatment of raw materials is disclosed, through acid treatment and The specific process of low temperature treatment; (3) clarified why pretreatment can improve the principle of yield, specifically as follows:
本发明利用酸预先处理过的低温天然石墨浆料作为超临界流体剥离的原料，由于石墨的温度较低，当快速喷入到高温环境中，会受到强烈的热冲击，石墨颗粒层间将发生微爆裂，这就为后续的分子插层提供了有利的突破口。其次，天然石墨经过酸微弱处理后，表面上附着一定数量的极性含氧官能团(羟基、羧基)，在超临界流体插层过程中，极性含氧官能团通过双极性相吸作用能够吸附超临界状态的有机溶剂极性分子，当插层分子堆垛在已经微破裂的石墨层间的通道口，方便了超临界流体分子完成插层过程，大大提高了石墨烯产率。最后，由于极性含氧官能团在超临界流体环境(高温高压)中会被还原，因此并没有影响石墨烯的本征特性。将酸预先处理过的低温天然石墨浆料作为进料，与常温天然石墨作为进料相比，通过超临界流体剥离过程，石墨烯的产率提高约为2～5倍。本发明不但提高了石墨烯的产率，而且也保持了石墨烯具有的电性能和热性能。The present invention utilizes low-temperature natural graphite slurry pre-treated by acid as the raw material for supercritical fluid exfoliation. Due to the low temperature of graphite, when it is quickly sprayed into a high-temperature environment, it will be subject to strong thermal shock, and graphite particle layers will Microburst, which provides a favorable breakthrough for subsequent molecular intercalation. Secondly, after the natural graphite is weakly treated with acid, a certain number of polar oxygen-containing functional groups (hydroxyl, carboxyl) are attached to the surface. During the supercritical fluid intercalation process, the polar oxygen-containing functional groups can adsorb The organic solvent polar molecules in the supercritical state, when the intercalation molecules are stacked at the channel opening between the micro-cracked graphite layers, it is convenient for the supercritical fluid molecules to complete the intercalation process, and the graphene yield is greatly improved. Finally, since the polar oxygen-containing functional groups are reduced in a supercritical fluid environment (high temperature and pressure), it does not affect the intrinsic properties of graphene. The low-temperature natural graphite slurry that has been pretreated by acid is used as the feed material. Compared with the normal temperature natural graphite as the feed material, the yield of graphene is increased by about 2 to 5 times through the supercritical fluid exfoliation process. The invention not only improves the yield of graphene, but also maintains the electrical and thermal properties of graphene.
附图说明Description of drawings
图1为本发明实施例得到的石墨烯的AFM图。Fig. 1 is the AFM picture of the graphene that the embodiment of the present invention obtains.
具体实施方式Detailed ways
本发明的实施例详细说明如下，本实施例在以本发明技术方案为前提下进行实施，给出了详细的实施方式和具体的操作过程，但本发明的保护范围不限于下述的实施例。Embodiments of the present invention are described in detail as follows. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation and specific operation process are provided, but the protection scope of the present invention is not limited to the following embodiments. .
对天然石墨预处理提高超临界流体制备石墨烯产率的方法，采用以下步骤：The method for improving the yield of graphene prepared by supercritical fluid to natural graphite pretreatment adopts the following steps:
(1)将天然石墨粉和酸加入到容器中并搅拌均匀，其中的天然石墨粉和酸的重量比为1∶10～10∶1，采用的酸为浓度大于70wt％的硫酸、浓度大于65wt％的硝酸或浓度大于37wt％的盐酸，天然石墨粉和酸搅拌处理5～60分钟；(1) Add natural graphite powder and acid to the container and stir evenly. The weight ratio of natural graphite powder and acid is 1: 10 to 10: 1. The acid used is sulfuric acid with a concentration greater than 70wt% and a concentration greater than 65wt. % nitric acid or hydrochloric acid with a concentration greater than 37wt%, natural graphite powder and acid were stirred for 5 to 60 minutes;
(2)过滤或分离多余的酸，然后在物料中加入乙二醇或乙醇添加剂并搅拌均匀，添加量为石墨粉重量的0.1～5％；(2) filter or separate excess acid, then add ethylene glycol or ethanol additive in the material and stir evenly, the addition amount is 0.1～5% of graphite powder weight;
(3)将上述物料转移到低温容器中并降温至-30～0℃，得到低温的石墨浆料；(3) Transfer the above-mentioned materials to a low-temperature container and lower the temperature to -30-0° C. to obtain a low-temperature graphite slurry;
(4)将低温石墨浆料快速喷入到盛有超临界流体介质的高压反应釜中，可以使用的超临界流体介质包括有二氧化碳、乙醇、N-甲基吡咯烷酮、二甲基乙酰胺、1-十二烷基-2-吡咯烷酮、二甲基甲酰胺、二甲亚矾、异丙醇、N-辛基-2-吡咯烷酮、丙酮、四氢呋喃、环己烷或甲醇；(4) The low-temperature graphite slurry is quickly sprayed into a high-pressure reactor filled with a supercritical fluid medium. The supercritical fluid medium that can be used includes carbon dioxide, ethanol, N-methylpyrrolidone, dimethylacetamide, 1 - dodecyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, isopropanol, N-octyl-2-pyrrolidone, acetone, tetrahydrofuran, cyclohexane or methanol;
(5)控制高压反应釜中物料的温度和压力接近超临界流体介质的临界温度和压力，，并使得物料在高压反应釜中停留进行超临界处理，例如，采用二氧化碳作为超临界流体介质时，高压反应釜中物料的温度为35℃、压力为7.5Mpa、物料停留时间为60分钟；采用乙醇作为超临界流体介质时，物料温度为245℃、压力为6.5Mpa、停留时间为50分钟；二甲基乙酰胺为超临界流体介质时，物料温度为270℃、压力为6Mpa、停留时间为40分钟；(5) control the temperature and pressure of the material in the autoclave to be close to the critical temperature and pressure of the supercritical fluid medium, and make the material stay in the autoclave for supercritical treatment, for example, when using carbon dioxide as the supercritical fluid medium, The temperature of the material in the high-pressure reactor is 35°C, the pressure is 7.5Mpa, and the residence time of the material is 60 minutes; when ethanol is used as the supercritical fluid medium, the temperature of the material is 245°C, the pressure is 6.5Mpa, and the residence time is 50 minutes; When methylacetamide is a supercritical fluid medium, the material temperature is 270°C, the pressure is 6Mpa, and the residence time is 40 minutes;
(6)将超临界处理后的物料快速喷入到常压产料罐内；(6) Rapidly spray the supercritically treated material into the normal pressure production tank;
(7)过滤、分离产料罐内的物料并真空干燥，干燥温度为35～100℃，干燥时间为1～12小时，得到石墨烯产物。(7) Filtrating and separating the materials in the production tank and drying them in vacuum, the drying temperature is 35-100° C., and the drying time is 1-12 hours to obtain graphene products.
以下进行详细说明。The details will be described below.
实施例1Example 1
按10∶1的重量比将天然石墨粉和95％的浓硫酸，加入到容器中，采用超声搅拌方式，搅拌20分钟后，将多余酸过滤掉。按石墨粉重量的3％加入乙醇，并搅拌均匀。将物料转移到低温容器中，使物料降到-10℃。然后将低温物料快速喷入到盛有超临界乙醇的高压反应釜中，高压反应釜的温度维持在245℃，压力为6.5MPa。物料在高压釜中停留60分钟后，快速喷入到常压产料罐中。将物料过滤、分离、清洗、干燥和收集固体产物。固体产物再次加入到新鲜的二甲基甲酰胺溶液中，利用超声波作用分散，时间为120min，静置12小时，再采用离心分离方式(3000r/min，10min)将沉淀去除，最后得到石墨烯分散液产物。通过测试分析表明，物料经高压釜循环一次的石墨烯产率达到了～23％，比原料未经预处理的产率提高近2.6倍。Add the natural graphite powder and 95% concentrated sulfuric acid into the container according to the weight ratio of 10:1, and use ultrasonic stirring method, after stirring for 20 minutes, filter out the excess acid. Add ethanol by 3% of graphite powder weight, and stir evenly. Transfer the material to a cryogenic container and allow the material to cool to -10°C. Then the low-temperature material is quickly sprayed into a high-pressure reactor filled with supercritical ethanol, and the temperature of the high-pressure reactor is maintained at 245° C. and the pressure is 6.5 MPa. After the material stays in the autoclave for 60 minutes, it is quickly sprayed into the normal pressure production tank. The material was filtered, separated, washed, dried and the solid product collected. The solid product was added to a fresh dimethylformamide solution again, dispersed by ultrasonic waves for 120 minutes, left to stand for 12 hours, and then the precipitate was removed by centrifugal separation (3000r/min, 10min), and finally the graphene dispersion was obtained. liquid product. The test analysis shows that the graphene yield of the material after one cycle of the autoclave reaches ~23%, which is nearly 2.6 times higher than that of the raw material without pretreatment.
实施例2Example 2
按1∶2的重量比将天然石墨粉和80％的浓盐酸，加入到容器中，采用机械搅拌方式，搅拌40分钟后，将多余酸过滤掉。按石墨粉重量的5％加入乙醇，并搅拌均匀。将物料转移到低温容器中，使物料降到-20℃。然后将低温物料快速喷入到盛有超临界N-甲基吡咯烷酮的高压反应釜中，高压反应釜的温度维持在445℃，压力为4.8MPa。物料在高压釜中停留90分钟后，快速喷入到常压产料罐中。将物料过滤、分离、清洗、干燥和收集固体产物。固体产物再次加入到新鲜的二甲基甲酰胺溶液中，利用超声波作用分散，时间为120min，静置12小时，再采用离心分离方式(3000r/min，10min)将沉淀去除，最后得到石墨烯分散液产物。通过测试分析表明，物料经高压釜循环一次的石墨烯产率达到了～35％，比原料未经预处理的产率提高近2.4倍。Add natural graphite powder and 80% concentrated hydrochloric acid into the container according to the weight ratio of 1:2, adopt mechanical stirring method, and after stirring for 40 minutes, filter out excess acid. Add ethanol by 5% of graphite powder weight, and stir evenly. Transfer the material to a cryogenic container and allow the material to cool to -20°C. Then the low-temperature material is quickly sprayed into a high-pressure reactor filled with supercritical N-methylpyrrolidone. The temperature of the high-pressure reactor is maintained at 445° C. and the pressure is 4.8 MPa. After the material stays in the autoclave for 90 minutes, it is quickly sprayed into the normal pressure production tank. The material was filtered, separated, washed, dried and the solid product collected. The solid product was added to a fresh dimethylformamide solution again, dispersed by ultrasonic waves for 120 minutes, left to stand for 12 hours, and then the precipitate was removed by centrifugal separation (3000r/min, 10min), and finally the graphene dispersion was obtained. liquid product. The test analysis shows that the graphene yield of the material after one cycle of the autoclave reaches ~35%, which is nearly 2.4 times higher than that of the raw material without pretreatment.
实施例3Example 3
按1∶1的重量比将天然石墨粉和90％的浓硝酸，加入到容器中，采用机械搅拌方式，搅拌50分钟后，将多余酸离心分离掉。按石墨粉重量的1％加入乙二醇，并搅拌均匀。将物料转移到低温容器中，使物料降到-5℃。然后将低温物料快速喷入到盛有超临界二甲基甲酰胺的高压反应釜中，高压反应釜的温度维持在370℃，压力为6MPa。物料在高压釜中停留120分钟后，快速喷入到常压产料罐中。将物料过滤、分离、清洗、干燥和收集固体产物。固体产物再次加入到新鲜的二甲基甲酰胺溶液中，利用超声波作用分散，时间为120min，静置12小时，再采用离心分离方式(3000r/min，10min)将沉淀去除，最后得到石墨烯分散液产物。通过测试分析表明，物料经高压釜循环一次的石墨烯产率达到了～46％，比原料未经预处理的产率提高近3倍。图1为本实施例制备得到的石墨烯产品的AFM图，通过本发明公开的预处理，可以提高石墨烯的剥离产率，这是因为：当低温浆料快速喷入到高温环境中，会受到强烈的热冲击，造成石墨颗粒层间发生微爆裂，极大地方便了分子插层。其次，经酸微弱处理后，石墨表面上附着的极性官能团，有利于吸附插层极性分子；当插层分子堆垛在已经微破裂的石墨层间的通道口，显著促进了插层速率，因而大大提高了石墨烯产率。Add the natural graphite powder and 90% concentrated nitric acid into the container according to the weight ratio of 1:1, adopt the mechanical stirring method, and after stirring for 50 minutes, centrifuge off the excess acid. Add ethylene glycol by 1% of graphite powder weight, and stir evenly. Transfer the material to a cryogenic container and allow the material to cool to -5°C. Then the low-temperature material is quickly sprayed into a high-pressure reactor filled with supercritical dimethylformamide. The temperature of the high-pressure reactor is maintained at 370° C. and the pressure is 6 MPa. After the material stays in the autoclave for 120 minutes, it is quickly sprayed into the normal pressure production tank. The material was filtered, separated, washed, dried and the solid product collected. The solid product was added to a fresh dimethylformamide solution again, dispersed by ultrasonic waves for 120 minutes, left to stand for 12 hours, and then the precipitate was removed by centrifugal separation (3000r/min, 10min), and finally the graphene dispersion was obtained. liquid product. The test analysis shows that the graphene yield of the material after one cycle of the autoclave reaches ~46%, which is nearly 3 times higher than that of the raw material without pretreatment. Fig. 1 is the AFM figure of the graphene product that present embodiment prepares, by the pretreatment disclosed by the present invention, can improve the stripping yield of graphene, this is because: when low temperature slurry is sprayed into high temperature environment rapidly, will Under strong thermal shock, micro-bursts occur between graphite particle layers, which greatly facilitates molecular intercalation. Secondly, after weak acid treatment, the polar functional groups attached to the graphite surface are conducive to the adsorption of intercalation polar molecules; when the intercalation molecules are stacked at the channel openings between the micro-cracked graphite layers, the intercalation rate is significantly promoted. , thus greatly increasing the graphene yield.
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