JP2682486B2 - Purification method of carbon nanotubes - Google Patents

Purification method of carbon nanotubes

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JP2682486B2
JP2682486B2 JP7005873A JP587395A JP2682486B2 JP 2682486 B2 JP2682486 B2 JP 2682486B2 JP 7005873 A JP7005873 A JP 7005873A JP 587395 A JP587395 A JP 587395A JP 2682486 B2 JP2682486 B2 JP 2682486B2
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carbon nanotubes
carbon
metal catalyst
metal
liquid
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JPH08198611A (en
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鋭也 市橋
澄男 飯島
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日本電気株式会社
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【発明の詳細な説明】 DETAILED DESCRIPTION OF THE INVENTION

【0001】 [0001]

【産業上の利用分野】本発明は、カーボンナノチューブの精製方法、とりわけ金属触媒を用いて製造されたカーボンナノチューブの精製方法に関する。 The present invention relates to a method of purifying carbon nanotubes, especially relates to the purification method of carbon nanotubes prepared using a metal catalyst.

【0002】 [0002]

【従来の技術】数個以上の円筒状黒鉛層が同心円状に形成された通常のカーボンナノチューブは、円筒の大きさが一定でなく、従ってカーボンナノチューブの電気特性や化学特性には大きなばらつきがあった。 BACKGROUND OF THE INVENTION Several more usually cylindrical graphite layers are concentrically formed of carbon nanotubes, a not the size of the cylinder is constant, thus there is a large variation in the electrical characteristics and chemical properties of carbon nanotubes It was. そこで、チューブの形状が単層に制御された単原子層カーボンナノチューブの製造方法を、本発明者等は特願平5−3379 Therefore, a method of manufacturing a monolayer carbon nanotube shape of the tube is controlled to a single layer, the present inventors have Japanese Patent Application No. 5-3379
37号出願明細書にて提案した。 It was proposed in 37 patent application specification. この単原子層カーボンナノチューブは、放電電極の一方に炭素を、他方の電極に金属(鉄、コバルト、ニッケルなどの遷移金属)と炭素の混合物を用い、原料ガスに炭化水素を用いてアーク放電により製造される。 The monoatomic layer carbon nanotubes, while the carbon of the discharge electrodes, metal to the other electrode with a mixture of carbon (iron, cobalt, transition metals such as nickel) by arc discharge using a hydrocarbon source gas It is produced.

【0003】 [0003]

【発明が解決しようとする課題】しかし、上記の方法により得られる単原子層カーボンナノチューブは、金属触媒を用いて製造されるため、金属触媒とその炭化物及び非晶質炭素、グラファイト等のカーボンナノチューブ以外の炭素物質を不純物として含んでいた。 [0006] However, monolayer carbon nanotubes obtained by the method described above, because it is produced using a metal catalyst, a metal catalyst and a carbide thereof, and amorphous carbon, carbon nanotubes, such as graphite carbon materials other than contained as impurities. 従って、このカーボンナノチューブを産業上利用するためには上記不純物を取り除く必要があり、カーボンナノチューブの有する電気特性や化学特性の点を考えると、特に上記不純物の中でも金属触媒とその金属の炭化物を取り除く必要がある。 Therefore, in order to take advantage of this carbon nanotube INDUSTRIAL need to remove the impurities, considering the point of electrical characteristics and chemical properties possessed by the carbon nanotubes, in particular removing the metal catalyst and carbides of metals among the above-mentioned impurities There is a need. しかし、従来技術に、カーボンナノチューブ以外の炭素物質を、浮選や遠心分離により除去する方法は特開平6−228824号公報に示されているが、未精製カーボンナノチューブから金属触媒とその金属の炭化物などの金属不純物を取り除く方法はこれまで存在しなかった。 However, in the prior art, the carbon material other than carbon nanotubes, a method of removing by flotation or centrifugation is shown in JP-A-6-228824, the metal from the crude carbon nanotubes and a metal catalyst carbides how to remove the metal impurities, such as did not exist until now.

【0004】本発明の目的は、金属触媒を用いて製造されたカーボンナノチューブから、特に金属触媒とその炭化物を、さらにはカーボンナノチューブ以外の炭素物質をも除去することにある。 An object of the present invention, the carbon nanotubes manufactured using a metal catalyst, especially metal catalysts and their carbides, further, that also remove carbon materials other than carbon nanotubes.

【0005】 [0005]

【課題を解決するための手段】上記課題を解決するため、本発明の第1の発明は、金属触媒を用いて製造された金属触媒とその金属の炭化物を不純物として含む未精製カーボンナノチューブに、酸を加えることにより、前記不純物を溶解することを特徴とするカーボンナノチューブの精製方法である。 In order to solve the above problems SUMMARY OF THE INVENTION The first aspect of the present invention, the metal catalyst and carbides of the metals that are produced using a metal catalyst in raw carbon nanotubes as an impurity, by adding an acid, a method of purifying carbon nanotubes is characterized by dissolving the impurities.

【0006】第2の発明は、金属触媒を用いて製造された金属触媒とその金属の炭化物を不純物として含む未精製カーボンナノチューブを、液体中に粉砕、分散し、前記液体を磁場中を通過させることにより前記不純物を除去することを特徴とするカーボンナノチューブの精製方法である。 A second invention, the raw carbon nanotubes comprising producing metal catalysts and their metal carbides as an impurity by using a metal catalyst, crushed in a liquid, dispersed, passes in a magnetic field to said liquid a method of purifying carbon nanotubes is characterized by removing the impurities by.

【0007】第3の発明は、金属触媒を用いて製造された金属触媒と金属の炭化物とカーボンナノチューブ以外の炭素物質を不純物として含む未精製カーボンナノチューブを、液体中に粉砕、分散し、前記液体中に含まれる前記炭素物質を遠心分離または浮選により除去し、炭素物質を除去した後の液体に酸を加えて前記金属不純物を溶解するか、あるいは炭素物質を除去した後の液体を磁場中を通過させることにより前記金属不純物を除去することを特徴とするカーボンナノチューブの精製方法である。 A third aspect of the present invention, the raw carbon nanotubes including carbon materials other than manufacturing metal catalyst and metal carbide and carbon nanotubes using a metal catalyst as an impurity, crushed in a liquid, dispersed, the liquid the carbon material was removed by centrifugation or flotation contained in, or dissolve the metal impurities by adding an acid to a liquid after removal of the carbon material, or a magnetic field in a liquid after removal of the carbon material a method of purifying carbon nanotubes and removing the metal impurities by passing the.

【0008】 [0008]

【作用】本発明のカーボンナノチューブの精製方法は、 [Action] method of purifying carbon nanotubes of the present invention,
粗生成物を粉砕、攪拌し、遠心分離、浮選により非晶質炭素、グラファイト等のカーボンナノチューブ以外の炭素物質を除去し、さらに酸を加えて金属を溶かす、あるいは磁場中を通過させることにより金属不純物を除去し、カーボンナノチューブの純度を向上させるものである。 The crude product was pulverized, stirred, centrifuged, amorphous carbon by flotation, to remove the carbon material other than carbon nanotubes such as graphite, melting of metals by adding further acid, or by passing through the magnetic field the metal impurities were removed, to thereby improve the purity of the carbon nanotubes.

【0009】 [0009]

【実施例】本発明の一実施例を以下に示す。 An example of the embodiment of the present invention are shown below.

【0010】(実施例1)精製に用いた単原子層カーボンナノチューブの粗生成物は、放電電極の一方の電極(正電極)に炭素棒を、他方の電極(負電極)に金属(鉄、コバルト、ニッケル等の遷移金属)を含んだ炭素棒を用い、メタン、水素、ヘリウムの混合ガス雰囲気中でアーク放電により製造して得た。 [0010] (Example 1) crude product monolayer carbon nanotubes using the purification a carbon rod to one of the electrodes (positive electrodes) of the discharge electrodes, the other electrode (negative electrode) to the metal (iron, cobalt, used carbon rod containing a transition metal) such as nickel, obtained by prepared by arc discharge in methane, hydrogen, a mixed gas atmosphere of helium. この時の負電極には、炭素棒に穴を開け金属線(鉄線など)を挿入したものを使用し、これにより負電極として金属棒を用いた場合には電極が溶けてしまうような温度でも使用可能で、 The negative electrode at this time, using what was inserted metal wire pierced carbon rod (such as iron wire), thereby also at a temperature such that the electrodes will melt in the case of using a metal rod as a negative electrode It can be used,
挿入する金属線の本数により、炭素棒表面に露出する炭素と金属の面積比を制御できるため、金属の蒸発量を制御できる。 The number of inserted metal wire, it is possible to control the carbon and metal area ratio of exposed to carbon rod surface, can be controlled evaporation of the metal. 本実施例では、鉄線が挿入された炭素棒を負電極として用い、メタンガス20Torr、ヘリウムガス180Torr、水素ガス10Torrの雰囲気で、 In this embodiment, using a carbon rod iron wire is inserted as a negative electrode, methane 20 Torr, the helium gas 180 torr, in an atmosphere of hydrogen gas 10 Torr,
放電電圧30V、放電電流50Aでアーク放電させることにより、太さが1〜2nmで揃った大量の単層カーボンナノチューブを得た。 Discharge voltage 30 V, by arc discharge at a discharge current of 50A, to obtain a large amount of single-walled carbon nanotubes thickness is uniform at 1 to 2 nm.

【0011】上記方法により得られた単層カーボンナノチューブ粗生成物は、製造時に使用した金属触媒とその金属の炭化物、および非晶質炭素やグラファイト等のカーボンナノチューブ以外の炭素物質を不純物として含んでいる。 [0011] The single-walled carbon nanotubes crude product obtained by the method include a metal catalyst and carbide of the metal which is used in the production, and the amorphous carbon material other than carbon nanotubes such as carbon or graphite as an impurity there. そこで、上記方法により得られた粗生成物を、 Therefore, the crude product obtained by the above method,
スチールボールとエタノールを入れた容器に入れ、加振器(たとえば超音波をかける)で粉砕し、液中に攪拌した。 Placed in a container with steel balls and ethanol and triturated with shaker (e.g. applying ultrasound), it was stirred into the liquid. この溶液を遠心分離器にかけ、上澄みを取り除くことにより、非晶質炭素、グラファイト等の微小な球状粒子を取り除いた。 The solution subjected to centrifugal separator, by removing the supernatant was removed amorphous carbon, fine spherical particles such as graphite. さらに、この上澄みを取り除いた試料に硝酸を加えることにより鉄を溶かし、単原子層カーボンナノチューブの精製を行った。 Furthermore, dissolved iron by adding nitric acid to the sample was removed the supernatant, it was purified monoatomic layer carbon nanotube. これにより、金属触媒を用いて製造されたカーボンナノチューブから、金属触媒とその炭化物を、さらにはカーボンナノチューブ以外の炭素物質をも除去することができた。 Thus, the carbon nanotubes manufactured using a metal catalyst, a metal catalyst and a carbide thereof, more could also remove carbon materials other than carbon nanotubes. 酸としては、硝酸の他に塩酸なども使用でき、酸を加えて加温する方が好ましい。 As the acid, such as addition of hydrochloric acid and nitric may be used, it is preferable to heat by the addition of acid. この際の温度は、酸が沸騰しない温度(約1 Temperature at this time, the acid is not boiling temperature (about 1
00℃)以下であればよい。 00 ℃) may be any less.

【0012】(実施例2)上澄みを取り除くまでは実施例1と同じ精製を行った。 [0012] Until remove (Example 2) The supernatant was subjected to the same purification as in Example 1. その後、本実施例では、上澄みを取り除いた溶液を磁場中を通過させることにより、 Then, in this embodiment, by passing through the magnetic field of a solution obtained by removing the supernatant,
鉄を除去し、単原子層カーボンナノチューブの精製を行った。 Iron was removed and was purified monoatomic layer carbon nanotube. 本実施例の方法によっても、金属触媒を用いて製造されたカーボンナノチューブから、金属触媒とその炭化物、およびカーボンナノチューブ以外の炭素物質を除去することができた。 Also by the method of the present embodiment, it could be removed from the carbon nanotubes manufactured using a metal catalyst, a metal catalyst and a carbide thereof, and a carbon material other than carbon nanotubes.

【0013】 [0013]

【発明の効果】本発明によれば、金属触媒を用いて製造されたカーボンナノチューブ中の、金属触媒やその炭化物を、さらには非晶質炭素、グラファイト等の炭素物質をも除去することができる。 According to the present invention, in the carbon nanotubes prepared using a metal catalyst, a metal catalyst and a carbide thereof, and further can also remove amorphous carbon, carbon materials such as graphite . これにより、チューブの形状が単層に制御され、かつ純度の高いカーボンナノチューブが得られる。 Thus, the shape of the tube is controlled to a single layer, and high carbon nanotube purity is obtained.

Claims (3)

    (57)【特許請求の範囲】 (57) [the claims]
  1. 【請求項1】金属触媒を用いて製造された前記金属触媒と前記金属の炭化物を不純物として含む未精製カーボンナノチューブに、酸を加えることにより、前記不純物を溶解することを特徴とするカーボンナノチューブの精製方法。 The method according to claim 1 wherein said metal catalyst and carbides of the metals that are produced using a metal catalyst in raw carbon nanotubes as an impurity, by adding an acid, the carbon nanotube, which comprises dissolving the impurities purification methods.
  2. 【請求項2】金属触媒を用いて製造された前記金属触媒と前記金属の炭化物を不純物として含む未精製カーボンナノチューブを、液体中に粉砕、分散し、前記液体を磁場中を通過させることにより前記不純物を除去することを特徴とするカーボンナノチューブの精製方法。 2. A method unpurified carbon nanotubes comprising carbides of the metals and the metal catalyst produced using a metal catalyst as an impurity, crushed in a liquid, dispersed, said by passing through the magnetic field the liquid method of purifying carbon nanotubes, characterized in that the removal of impurities.
  3. 【請求項3】金属触媒を用いて製造された前記金属触媒と前記金属の炭化物とカーボンナノチューブ以外の炭素物質を不純物として含む未精製カーボンナノチューブを、液体中に粉砕、分散し、前記液体中に含まれる前記炭素物質を遠心分離または浮選により除去し、 前記炭素物質を除去した後の液体に酸を加えて前記金属不純物を溶解するか、あるいは前記炭素物質を除去した後の液体を磁場中を通過させることにより前記金属不純物を除去することを特徴とするカーボンナノチューブの精製方法。 The method according to claim 3 Unrefined carbon nanotubes including carbon material other than the carbide and carbon nanotubes of the metal and the metal catalyst produced using a metal catalyst as an impurity, crushed in a liquid, dispersed in the liquid the carbon material was removed by centrifugation or flotation, or dissolve the metal impurities acid is added to the liquid after removal of the carbon material, or a magnetic field in a liquid after removal of the carbon material included method of purifying carbon nanotubes and removing the metal impurities by passing the.
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JP2010174419A (en) * 2009-01-30 2010-08-12 Showa Denko Kk Apparatus for removing iron-based impurities in vapor grown carbon fibers
US8449858B2 (en) 2009-06-10 2013-05-28 Carbon Solutions, Inc. Continuous extraction technique for the purification of carbon nanomaterials
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