Carbon nanotube purification device and purification method
阅读说明：本技术 碳纳米管纯化装置及纯化方法 (Carbon nanotube purification device and purification method ) 是由 王金娥 董明 于 2019-11-07 设计创作，主要内容包括：一种碳纳米管纯化装置及纯化方法,属于纳米材料制备技术领域。该碳纳米管纯化装置包括低温预热区、高温纯化区以及降温冷凝区；低温预热区设有碘升华仓,碘升华仓设置在加热套中；高温纯化区设有碳纳米管存储仓,碳纳米管存储仓设置在加热套中；降温冷凝区设有冷凝回收仓；碘升华仓、碳纳米管存储仓及冷凝回收仓依次通过法兰连接,并在法兰连接处填充硼硅酸盐玻璃隔热毡隔热,碘升华仓及冷凝回收仓设有通气孔。本发明通过引入碘单质与金属催化剂反应,生成碘化物,利用碘化物易挥发的特性实现碳纳米管粉体的纯化。(A carbon nano tube purification device and a purification method belong to the technical field of nano material preparation. The carbon nano tube purifying device comprises a low-temperature preheating zone, a high-temperature purifying zone and a cooling and condensing zone; the low-temperature preheating zone is provided with an iodine sublimation bin which is arranged in the heating sleeve; the high-temperature purification area is provided with a carbon nano tube storage bin which is arranged in the heating sleeve; the cooling condensation area is provided with a condensation recovery bin; the iodine sublimation bin, the carbon nanotube storage bin and the condensation recovery bin are sequentially connected through flanges, borosilicate glass heat insulation felt is filled at the flange connection position for heat insulation, and vent holes are formed in the iodine sublimation bin and the condensation recovery bin. The invention generates iodide by introducing iodine simple substance to react with metal catalyst, and realizes the purification of carbon nano tube powder by utilizing the characteristic of easy volatilization of the iodide.)
1. A carbon nanotube purification device is characterized by comprising a low-temperature preheating zone, a high-temperature purification zone and a cooling and condensing zone; the low-temperature preheating zone is provided with an iodine sublimation bin which is arranged in the heating sleeve; the high-temperature purification area is provided with a carbon nano tube storage bin which is arranged in the heating sleeve; the cooling condensation area is provided with a condensation recovery bin;
the iodine sublimation bin, the carbon nanotube storage bin and the condensation recovery bin are sequentially connected through flanges, and borosilicate glass heat insulation felt is filled at the flange connection part for heat insulation;
the iodine sublimation bin and the condensation recovery bin are provided with vent holes.
2. The carbon nanotube purification apparatus according to claim 1, wherein the low-temperature preheating zone has a temperature of 100 to 200 ℃, the high-temperature purification zone has a temperature of 500 to 800 ℃, and the reduced-temperature condensation zone has a temperature of 80 to room temperature.
3. The carbon nanotube purification apparatus of claim 1, wherein the iodine sublimation chamber, the carbon nanotube storage chamber and the condensation recovery chamber are made of one of borosilicate glass, quartz and graphite.
4. The carbon nanotube purification apparatus of claim 3, wherein the iodine sublimation chamber is made of borosilicate glass or quartz, and the heating jacket of the iodine sublimation chamber is provided with a peep window for manual judgment of the purification process.
5. A method for purifying carbon nanotubes, which comprises the steps of using the purification apparatus according to any one of claims 1 to 4 to perform the purification, comprising:
s1, filling the carbon nano tube to be purified into a carbon nano tube storage bin, and placing the excessive iodine simple substance into an iodine sublimation bin; then the iodine sublimation bin, the carbon nano tube storage bin and the condensation recovery bin are sequentially connected through flanges, and borosilicate glass heat insulation felt is filled at the flange connection part for heat insulation;
s2, vacuumizing to 0.01-1 Pa, heating the high-temperature purification area to 500-800 ℃, heating the low-temperature preheating area to 100-200 ℃, introducing inert gas to enable iodine vapor in the low-temperature preheating area to enter the high-temperature purification area to react with impurities in the carbon nano tubes to obtain iodides, volatilizing the generated iodides, entering the low-temperature condensation area, and condensing and crystallizing;
and S3, stopping heating after the reaction is sufficient, naturally cooling to room temperature, stopping ventilation, moving out the carbon nanotube storage bin, and collecting the purified carbon nanotubes.
6. The method for purifying carbon nanotubes as claimed in claim 5, wherein after the purified carbon nanotubes are collected, the condensation recovery bin is abutted to the iodine sublimation bin via flanges, the condensation recovery bin is heated and air is introduced, and the iodine sublimation bin is cooled by water to recover elemental iodine.
7. The method for purifying carbon nanotubes as claimed in claim 5, wherein the weight ratio of excess iodine to carbon nanotubes is greater than 25%.
8. The method for purifying carbon nanotubes according to claim 5, wherein the flow rate of the inert gas during the purification process is in the range of 1 to 4L/min.
Technical Field
The invention relates to a technology in the field of nano material preparation, in particular to a carbon nano tube purification device and a purification method.
Background
The carbon nano tube has special structural characteristics, remarkable physical and chemical properties and potential application value in the future high-tech field, is a research front and a hot spot in the fields of physics, chemistry, biology, materials and the like, and has wide application prospect in the fields of nano electronic devices, catalyst carriers, electrochemical materials, composite materials and the like.
The existing methods for preparing carbon nanotubes mainly include arc discharge methods, laser etching methods, chemical vapor deposition methods, solid phase pyrolysis methods, flame synthesis methods, glow discharge methods, polymerization synthesis methods, and the like. In many carbon nanotube preparation processes, catalysts are required in other methods except some direct current arc methods which do not require catalysts. The catalyst is selected from transition metals such as iron, cobalt, nickel, manganese and the like and oxides thereof. Along with the growth of the carbon nano tube, the metal active component is coated by the carbon layer to cause the inactivation of the catalyst, so that the metal catalyst is inevitably remained in the obtained crude product of the carbon nano tube, and the existence of the metal impurities can directly influence the performance of the carbon nano tube, thereby greatly restricting the application of the carbon nano tube in various fields. Therefore, in order to obtain high purity carbon nanotubes, the crude carbon nanotubes must be purified.
The process of removing metal impurities from carbon nanotubes is called purification. At present, most of the metal catalysts in the carbon nanotubes are removed by a chemical method, and according to the properties of catalyst particles, the catalyst particles react with chemical reagents such as gas, acid, salt and the like to generate volatile or soluble substances, so that the effects of separation and purification are achieved. Rong of Qinghua university (CN1436722A), etc. utilizes vacuum high-temperature operation to effectively remove the transition metal catalyst and the metal oxide carrier mixed in the carbon nano tube, in particular to the transition metal catalyst coated by a carbon layer, and the purity of the purified carbon nano tube can reach more than 99.9 percent. However, the method has long reaction time and high energy consumption and can not be operated continuously. The technical scheme includes that (CN101130431A) original multi-wall carbon nano tubes/carbon nano fibers are subjected to high-temperature graphitization treatment (1800 plus 3000 ℃) to remove metal catalysts and other high-temperature volatile impurities and eliminate defects in the multi-wall carbon nano tubes, then graphitized carbon nano tubes/carbon nano fiber samples with different carbon structures are subjected to uniform dispersion through dispersant solution ultrasound, the different carbon structures form discrete phases, and finally discrete carbon nano particles in. The method needs high-temperature graphitization, has high energy consumption, simultaneously needs a solvent, a dispersing agent and the like, and has complex subsequent treatment. Nippon Sony corporation, WEIPUShanzhu, et al (CN10746745A) adds chemical substances capable of complexing with metal catalyst, such as aminopolycarboxylic acid, to form complex, and removes the complex by centrifugation, etc. to achieve the purification effect. The Beijing university Guowei et al (CN101780951A) and the literature disclose that the purification of carbon nanotubes by liquid phase acid treatment only removes the metal impurities exposed outside the carbon nanotubes, but the metal impurities in the carbon nanotubes are mainly concentrated inside the ports and the cavities, so the metal impurities sealed inside the ports and the cavities of the carbon nanotubes cannot be effectively removed, the purification effect is limited, and in addition, the method needs a large amount of acid, and the subsequent treatment is inconvenient.
The present invention has been made to solve the above-mentioned problems occurring in the prior art.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a carbon nano tube purification device and a purification method, which generate iodide by introducing an iodine simple substance to react with a metal catalyst, and realize the purification of carbon nano tube powder by utilizing the characteristic of easy volatilization of the iodide.
The invention provides a carbon nano tube purification device, which comprises a low-temperature preheating zone, a high-temperature purification zone and a cooling and condensing zone, wherein the low-temperature preheating zone is arranged above the high-temperature purification zone;
the low-temperature preheating zone is an iodine sublimation zone and is provided with an iodine sublimation bin, and the iodine sublimation bin is arranged in the heating sleeve;
the high-temperature purification area is an impurity removal area and is provided with a carbon nano tube storage bin which is arranged in the heating sleeve;
the temperature reduction condensation area is a volatile product condensation crystallization area and is provided with a condensation recovery bin;
the iodine sublimation bin, the carbon nanotube storage bin and the condensation recovery bin are sequentially connected through flanges, borosilicate glass heat insulation felt is filled in the flange connection position for heat insulation, and vent holes are formed in the iodine sublimation bin and the condensation recovery bin.
The temperature range of the low-temperature preheating zone is 100-200 ℃, the temperature range of the high-temperature purification zone is 500-800 ℃, and the temperature range of the cooling condensation zone is 80-room temperature.
Iodine sublimation storehouse, carbon nanotube storage storehouse and condensation are retrieved the storehouse and can select for use borosilicate glass, quartz material, graphite material respectively and make, prefer quartz material.
The iodine sublimation bin is made of high borosilicate glass or quartz, and the heating sleeve on the iodine sublimation bin is provided with a peeping window for manually judging the purification process, so that the purification is finished when no iodine vapor is seen.
The second aspect of the present invention provides a method for purifying carbon nanotubes, comprising the steps of:
s1, filling the carbon nano tube to be purified into a carbon nano tube storage bin, and placing the excessive iodine simple substance into an iodine sublimation bin; then the iodine sublimation bin, the carbon nano tube storage bin and the condensation recovery bin are sequentially connected through flanges, and borosilicate glass heat insulation felt is filled at the flange connection part for heat insulation;
s2, vacuumizing to 0.01-1 Pa, heating the high-temperature purification area to 500-800 ℃, heating the low-temperature preheating area to 100-200 ℃, introducing inert gas to enable iodine vapor in the low-temperature preheating area to enter the high-temperature purification area to react with impurities in the carbon nano tubes to obtain iodides, volatilizing the generated iodides, entering the low-temperature condensation area, and condensing and crystallizing;
and S3, stopping heating after the reaction is sufficient, naturally cooling to room temperature, stopping ventilation, moving out the carbon nanotube storage bin, and collecting the purified carbon nanotubes.
Preferably, after the purified carbon nanotubes are collected, the condensation recovery bin is butted with the iodine sublimation bin through a flange, the condensation recovery bin is heated and air is introduced, and meanwhile, the iodine sublimation bin is cooled by water to recover iodine simple substances; oxygen in the air reacts with iodide to displace iodine, and the iodine is condensed and crystallized in an iodine sublimation bin.
Taking the metal catalyst iron as an example, the chemical reaction occurring in the purification process is as follows:
the iodine simple substance is recovered, and the chemical reaction is as follows:
preferably, the excess elemental iodine to carbon nanotube weight ratio is greater than 25%.
Preferably, the flow range of the inert gas in the purification process is 1-4L/min.
Technical effects
Compared with the prior art, the invention has the following technical effects:
1) iodine is introduced to react with a metal catalyst to generate iodide, and the purification of the carbon nano tube powder is realized by utilizing the characteristic of easy volatilization of the iodide;
2) the method can remove metal impurities exposed outside the carbon nano tube, can also effectively remove metal impurities sealed at the end of the carbon nano tube and in the cavity, has obvious purification effect, can prepare the carbon nano tube with the purity of 99.99 percent, and is suitable for batch purification operation of crude products of the carbon nano tube containing the metal catalyst;
2) the iodine simple substance can be recycled, the cost is saved, and the environment is protected without pollution.
Drawings
FIG. 1 is a schematic view of a carbon nanotube purification apparatus according to example 1;
FIG. 2a is a TEM image of crude carbon nanotubes in example 1;
FIG. 2b is a TEM image of the purified carbon nanotube sample of example 1;
FIG. 3a is the EDS diagram of the crude carbon nanotube in example 1;
FIG. 3b is an EDS diagram of a sample of purified carbon nanotubes of example 1;
in the figure: an iodine sublimation bin 1, a carbon nano
Detailed Description
The invention is described in detail below with reference to the drawings and the detailed description.
As shown in fig. 1, an embodiment of the present invention relates to a carbon nanotube purification apparatus, which includes a low-temperature preheating region, a high-temperature purification region, and a cooling condensation region;
the low-temperature preheating zone is an iodine sublimation zone and is provided with an iodine sublimation bin 1, and the iodine sublimation bin is arranged in a heating jacket (not shown in the attached drawing);
the high-temperature purification area is an impurity removal area and is provided with a carbon nano
the temperature reduction condensation area is a volatile product condensation crystallization area and is provided with a condensation recovery bin 3;
iodine sublimation storehouse 1, carbon
The temperature range of the low-temperature preheating zone is 100-200 ℃, the temperature range of the high-temperature purification zone is 500-800 ℃, and the temperature range of the cooling condensation zone is 80-room temperature.
The iodine sublimation bin, the carbon nano tube storage bin and the condensation recovery bin are preferably made of quartz materials.
The heating jacket on the iodine sublimation bin is provided with a peep window (not shown in the attached drawing) for manually judging the purification process, and the purification is finished when no iodine vapor is seen.
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