JP2008290918A - Method for manufacturing multilayer carbon nanotube and multilayer carbon nanotube - Google Patents
Method for manufacturing multilayer carbon nanotube and multilayer carbon nanotube Download PDFInfo
- Publication number
- JP2008290918A JP2008290918A JP2007139596A JP2007139596A JP2008290918A JP 2008290918 A JP2008290918 A JP 2008290918A JP 2007139596 A JP2007139596 A JP 2007139596A JP 2007139596 A JP2007139596 A JP 2007139596A JP 2008290918 A JP2008290918 A JP 2008290918A
- Authority
- JP
- Japan
- Prior art keywords
- carbon nanotube
- walled carbon
- catalyst
- iron
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 239000002041 carbon nanotube Substances 0.000 title claims abstract description 13
- 229910021393 carbon nanotube Inorganic materials 0.000 title claims abstract description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 105
- 238000010438 heat treatment Methods 0.000 claims abstract description 60
- 239000003054 catalyst Substances 0.000 claims abstract description 58
- 229910052742 iron Inorganic materials 0.000 claims abstract description 49
- 239000000843 powder Substances 0.000 claims abstract description 46
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 30
- 239000002223 garnet Substances 0.000 claims abstract description 20
- 238000001947 vapour-phase growth Methods 0.000 claims abstract description 20
- 230000003197 catalytic effect Effects 0.000 claims abstract description 17
- 239000002048 multi walled nanotube Substances 0.000 claims description 123
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 36
- 239000011707 mineral Substances 0.000 claims description 36
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 29
- 238000010521 absorption reaction Methods 0.000 claims description 28
- 238000003917 TEM image Methods 0.000 claims description 14
- 239000000377 silicon dioxide Substances 0.000 claims description 10
- 238000001237 Raman spectrum Methods 0.000 claims description 7
- 239000004576 sand Substances 0.000 claims description 7
- 239000002071 nanotube Substances 0.000 claims 1
- 238000007796 conventional method Methods 0.000 abstract description 2
- 238000002425 crystallisation Methods 0.000 abstract 1
- 230000008025 crystallization Effects 0.000 abstract 1
- 239000007789 gas Substances 0.000 description 36
- 239000010410 layer Substances 0.000 description 26
- 238000000862 absorption spectrum Methods 0.000 description 20
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 18
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 16
- 239000012159 carrier gas Substances 0.000 description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 9
- 229910052786 argon Inorganic materials 0.000 description 9
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 8
- KTWOOEGAPBSYNW-UHFFFAOYSA-N ferrocene Chemical compound [Fe+2].C=1C=C[CH-]C=1.C=1C=C[CH-]C=1 KTWOOEGAPBSYNW-UHFFFAOYSA-N 0.000 description 7
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000007740 vapor deposition Methods 0.000 description 5
- 239000000919 ceramic Substances 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- 239000013078 crystal Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000007921 spray Substances 0.000 description 4
- 238000005979 thermal decomposition reaction Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- -1 earth and lumber Substances 0.000 description 3
- 150000002506 iron compounds Chemical class 0.000 description 3
- 239000000395 magnesium oxide Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000012256 powdered iron Substances 0.000 description 3
- 239000002296 pyrolytic carbon Substances 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910052833 almandine Inorganic materials 0.000 description 2
- 229910052836 andradite Inorganic materials 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 239000010428 baryte Substances 0.000 description 2
- 229910052601 baryte Inorganic materials 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000003475 lamination Methods 0.000 description 2
- NIFIFKQPDTWWGU-UHFFFAOYSA-N pyrite Chemical compound [Fe+2].[S-][S-] NIFIFKQPDTWWGU-UHFFFAOYSA-N 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 229910000616 Ferromanganese Inorganic materials 0.000 description 1
- 239000006004 Quartz sand Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004453 electron probe microanalysis Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 229910052960 marcasite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 229910052683 pyrite Inorganic materials 0.000 description 1
- 239000011028 pyrite Substances 0.000 description 1
- 229910052611 pyroxene Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 229910052861 titanite Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Carbon And Carbon Compounds (AREA)
- Catalysts (AREA)
Abstract
Description
本発明は多層カーボンナノチューブの製造方法及び多層カーボンナノチューブに関し、更に詳細には触媒が存在し且つ所定温度に保持された加熱雰囲気内に炭素源気体を流通し、前記触媒の表面から多層カーボンナノチューブが成長する触媒気相成長法による多層カーボンナノチューブの製造方法及び多層カーボンナノチューブに関する。 The present invention relates to a method for producing multi-walled carbon nanotubes and multi-walled carbon nanotubes, and more specifically, a catalyst is present and a carbon source gas is circulated in a heated atmosphere maintained at a predetermined temperature. The present invention relates to a method for producing a multi-walled carbon nanotube by a catalytic vapor phase growth method and a multi-walled carbon nanotube.
多層カーボンナノチューブの製造方法としては、触媒が存在し且つ所定温度に保持された加熱雰囲気内に炭素源気体を流通して、金属触媒の表面から多層カーボンナノチューブを成長させる触媒気相成長法がある（例えば下記特許文献１、特許文献２参照）。
この触媒気相成長法では、金属触媒が存在し且つ多層カーボンナノチューブが形成される温度に加熱された加熱雰囲気内に、メタン等の炭化水素と水素又はアルゴン等のキャリアガスとの混合ガスを導入し、金属触媒の表面から多層カーボンナノチューブを成長させる。
かかる触媒気相成長法で用いられる金属触媒としては、主として鉄、コバルト、ニッケル等が用いられ、特に鉄が汎用されている。
この金属触媒としての鉄は、フェロセン等の有機鉄化合物を用いる方法（例えば下記特許文献３参照）、或いはアルミナ、シリカ、マグネシア等のセラミックに鉄を担持する方法（例えば特許文献４、特許文献５、特許文献６及び特許文献７参照）がある。
In this catalytic vapor deposition method, a mixed gas of a hydrocarbon such as methane and a carrier gas such as hydrogen or argon is introduced into a heated atmosphere heated to a temperature at which a metal catalyst is present and multi-walled carbon nanotubes are formed. Then, multi-walled carbon nanotubes are grown from the surface of the metal catalyst.
As a metal catalyst used in such a catalyst vapor phase growth method, iron, cobalt, nickel and the like are mainly used, and particularly iron is widely used.
The iron as the metal catalyst is a method using an organic iron compound such as ferrocene (for example, see Patent Document 3 below), or a method of supporting iron on a ceramic such as alumina, silica, magnesia (for example, Patent Document 4, Patent Document 5). Patent Document 6 and Patent Document 7).
かかる触媒気相成長法では、多層カーボンナノチューブを安定して得ることができ、現在、多層カーボンナノチューブの量産方法として採用されている。
しかし、従来の触媒気相成長法で得られた多層カーボンナノチューブは、そのままでは結晶化度が低いため、電導度、熱伝導度、強度が低く実用に供するには種々の問題が存在する。また、多層カーボンナノチューブの表面は、熱分解炭素被覆層で覆われている。
このため、従来の触媒気相成長法で得られた多層カーボンナノチューブは、その用途によっては、その生成温度を超える温度での高温加熱処理が施される。かかる高温加熱処理での加熱温度は、通常、２０００℃以上である。
この様な、高温加熱処理は、煩雑な作業で且つエネルギー的にも損失が伴う。また、高温加熱処理を施すことによって、多層カーボンナノチューブの表面を覆っていた熱分解炭素被覆層の結晶化度を向上できるものの、分散剤等を用いるなど、前処理をしなければ樹脂等との分散が不十分となることが判明した。
一方、高温加熱処理が未処理の多層カーボンナノチューブは、高温加熱処理を施した多層カーボンナノチューブに比較して、樹脂等との分散性が良好となる傾向があることも判明した。
また、従来の金属触媒として、フェロセン等の有機鉄化合物を用いる方法、或いはアルミナ、シリカ、マグネシア等のセラミックに鉄を担持する方法では、触媒の製造コストが高価であり、多層カーボンナノチューブの製造コストが高価となっている。
そこで、本発明は、高結晶化度の多層カーボンナノチューブを得るべく、触媒気相成長法で得た多層カーボンナノチューブに、その生成温度を超える高温加熱処理を施す従来の多層カーボンナノチューブの製造方法の課題を解消し、触媒気相成長法のみで高結晶化度の多層カーボンナノチューブを安価で得られる多層カーボンナノチューブの製造方法及び多層カーボンナノチューブを提供することを目的とする。
In such a catalytic vapor phase growth method, multi-walled carbon nanotubes can be obtained stably, and is currently employed as a mass production method for multi-walled carbon nanotubes.
However, since the multi-walled carbon nanotubes obtained by the conventional catalytic vapor phase growth method have low crystallinity as they are, there are various problems to put them into practical use because of low electrical conductivity, thermal conductivity and strength. The surface of the multi-walled carbon nanotube is covered with a pyrolytic carbon coating layer.
For this reason, the multi-walled carbon nanotubes obtained by the conventional catalytic vapor phase growth method are subjected to a high-temperature heat treatment at a temperature exceeding the generation temperature depending on the application. The heating temperature in such high-temperature heat treatment is usually 2000 ° C. or higher.
Such a high-temperature heat treatment is a complicated operation and involves energy loss. In addition, although the crystallinity of the pyrolytic carbon coating layer covering the surface of the multi-walled carbon nanotube can be improved by performing a high-temperature heat treatment, a resin or the like can be used unless a pretreatment is performed, such as using a dispersant. It was found that dispersion was insufficient.
On the other hand, it has also been found that multi-walled carbon nanotubes that have not been subjected to high-temperature heat treatment tend to have better dispersibility with resins or the like than multi-walled carbon nanotubes that have been subjected to high-temperature heat treatment.
In addition, in the method using an organic iron compound such as ferrocene as a conventional metal catalyst or the method of supporting iron on a ceramic such as alumina, silica or magnesia, the production cost of the catalyst is high, and the production cost of the multi-walled carbon nanotube Has become expensive.
Therefore, the present invention provides a conventional multi-walled carbon nanotube production method in which a multi-walled carbon nanotube obtained by catalytic vapor deposition is subjected to high-temperature heat treatment exceeding the generation temperature in order to obtain a multi-walled carbon nanotube with high crystallinity. An object of the present invention is to provide a method for producing a multi-walled carbon nanotube and a multi-walled carbon nanotube that can solve the problem and obtain a multi-walled carbon nanotube having a high crystallinity at a low cost only by catalytic vapor phase growth.
本発明者等は、前記課題を解決すべく種々検討した結果、触媒として鉄含有のガーネット粉末を用いたところ、触媒気相成長法のみで実用に耐え得る高結晶化度の多層カーボンナノチューブを得られることを見出し、本発明に到達した。
すなわち、本発明は、触媒が存在し且つ所定温度に保持された加熱雰囲気内に炭素源気体を流通して、前記触媒の表面から多層カーボンナノチューブを成長させる触媒気相成長法によって多層カーボンナノチューブを製造する際に、前記触媒として、鉄含有の鉱物粉末を用いることを特徴とする多層カーボンナノチューブの製造方法にある。
かかる本発明において、鉄含有の鉱物粉末として、鉄含有のガーネット粉末又は鉄含有の珪砂を好適に用いることができる。
更に、触媒として用いる鉄含有の鉱物粉末に、炭素源気体を流通する前に加熱処理を施すことによって、触媒単位重量当たりの多層カーボンナノチューブの収量を増大できる。
As a result of various studies to solve the above problems, the present inventors have used a garnet powder containing iron as a catalyst, and obtained a multi-walled carbon nanotube having a high crystallinity that can withstand practical use only by catalytic vapor deposition. The present invention has been reached.
That is, the present invention provides a multi-wall carbon nanotube by a catalyst vapor phase growth method in which a multi-wall carbon nanotube is grown from the surface of the catalyst by circulating a carbon source gas in a heated atmosphere in which a catalyst is present and maintained at a predetermined temperature. In production, the present invention resides in a method for producing a multi-walled carbon nanotube, wherein iron-containing mineral powder is used as the catalyst.
In the present invention, iron-containing garnet powder or iron-containing silica sand can be suitably used as the iron-containing mineral powder.
Furthermore, the yield of multi-walled carbon nanotubes per unit weight of the catalyst can be increased by subjecting the iron-containing mineral powder used as the catalyst to a heat treatment before circulating the carbon source gas.
また、本発明は、触媒が存在し且つ所定温度に保持された加熱雰囲気内に炭素源気体を流通する触媒気相成長法によって得られ、且つ前記加熱雰囲気の温度を超える高温での高温加熱処理が施されていない多層カーボンナノチューブであって、前記多層カーボンナノチューブの透過型電子顕微鏡写真において、前記多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の主たる部分が、互いに平行状態の層によって形成されていることを特徴とする多層カーボンナノチューブでもある。
かかる本発明において、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の中央部及びその近傍を形成する層が互いに平行状態の層によって形成されていることが好ましい。
具体的には、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の任意の箇所を幅方向に三等分したうち、その中間部分の幅で且つ前記多層カーボンナノチューブの長手方向に沿った長さ１０ｎｍの四角形の領域を形成する複数層が互いに平行状態であることが好ましい。
更に、本発明は、触媒が存在し且つ所定温度に保持された加熱雰囲気内に炭素源気体を流通する触媒気相成長法によって得られ、且つ前記加熱雰囲気温度を超える温度での高温加熱処理が施されていない多層カーボンナノチューブであって、前記多層カーボンナノチューブのラマンスペクトルが、その１３００ｃｍ−１付近の吸収ピークＤと１６００ｃｍ−１付近の吸収ピークＧとの比（Ｄ／Ｇ）が０．８以下であることを特徴とする多層カーボンナノチューブにある。
The present invention also provides a high-temperature heat treatment at a high temperature obtained by a catalyst vapor phase growth method in which a carbon source gas is circulated in a heated atmosphere in which a catalyst is present and maintained at a predetermined temperature, and exceeds the temperature of the heated atmosphere. In the transmission electron micrograph of the multi-walled carbon nanotube, the main parts of the laminated part surrounding the hollow part forming the linear part of the multi-walled carbon nanotube are parallel to each other. It is also a multi-walled carbon nanotube characterized by being formed of layers.
In the present invention, it is preferable that the central part of the laminated part surrounding the hollow part forming the linear part of the multi-walled carbon nanotube and the layer forming the vicinity thereof are formed by layers in parallel with each other.
Specifically, an arbitrary part of the laminated part surrounding the hollow part forming the linear part of the multi-walled carbon nanotube is divided into three equal parts in the width direction, and the width of the middle part and the longitudinal direction of the multi-walled carbon nanotube It is preferable that a plurality of layers forming a rectangular region having a length of 10 nm along each other are in a parallel state.
Furthermore, the present invention is obtained by a catalytic vapor phase growth method in which a carbon source gas is circulated in a heating atmosphere in which a catalyst is present and maintained at a predetermined temperature, and high-temperature heat treatment at a temperature exceeding the heating atmosphere temperature is performed. a multi-walled carbon nanotubes that have not been subjected the Raman spectrum of the multi-walled carbon nanotubes, the ratio of the absorption peak G in the vicinity of the absorption peak D and 1600 cm -1 in the vicinity of the 1300 cm -1 (D / G) is 0.8 The multi-walled carbon nanotube is characterized by the following.
本発明によれば、触媒気相成長法のみで実用に耐え得る高結晶化度の多層カーボンナノチューブを得ることができる。
その結果、触媒気相成長法で得られた多層カーボンナノチューブの結晶化度を向上すべく施す、その生成温度を超える高温加熱処理を省略でき、多層カーボンナノチューブの製造工程を簡略化でき且つ省エネルギーを図ることができる。
また、触媒として、鉄含有の鉱物粉末を用いるため、従来のフェロセン等の有機鉄化合物を触媒として用いる場合、或いはアルミナ、シリカ、マグネシア等のセラミックに鉄を担持したものを触媒として用いる場合に比較して、触媒コストを低減でき、多層カーボンナノチューブの製造コストの低減も図ることができる。
更に、本発明によって得られた多層カーボンナノチューブは、その表面が粗面に形成されており、比表面積を大とすることができ、樹脂等との分散性を向上できるものと期待できる。
According to the present invention, it is possible to obtain a multi-walled carbon nanotube having a high crystallinity that can withstand practical use only by the catalytic vapor deposition method.
As a result, it is possible to omit the high-temperature heat treatment exceeding the generation temperature, which is performed to improve the crystallinity of the multi-walled carbon nanotubes obtained by the catalytic vapor deposition method, simplify the multi-walled carbon nanotube manufacturing process and save energy. Can be planned.
In addition, since iron-containing mineral powder is used as a catalyst, it is compared with the case where a conventional organic iron compound such as ferrocene is used as a catalyst, or the case where iron is supported on a ceramic such as alumina, silica, magnesia or the like. Thus, the catalyst cost can be reduced, and the production cost of the multi-walled carbon nanotube can be reduced.
Furthermore, the multi-walled carbon nanotubes obtained by the present invention are expected to have a rough surface, increase the specific surface area, and improve the dispersibility with a resin or the like.
本発明では、触媒として、鉄含有の鉱物粉末を用いることが肝要である。この鉄含有の鉱物としては、鉄含有のガーネット、鉄含有のかんらん石、鉄含有のスピネル、鉄含有の輝石、白鉄鉱、黄鉄鉱、チタン鉄鉱、鉄重石、鉄マンガン重石、ギレスピー石、磁苦土鉱、鉄含有の珪砂等を挙げることができる。こられの鉱物は、製鉄原料、土木材、研磨材等に広く利用されており、高品質で且つ組成及び結晶構造が一定のものを安価に入手できる。
また、これらの鉄含有の鉱物粉末は、天然に産出した鉱物由来のものであってもよく、人工的に合成された鉱物由来のものであってもよい。
特に、かかる鉄含有の鉱物粉末のうち、鉄含有のガーネットや珪砂を好適に用いることができる。工業的にガーネットは研磨材として用いられており、珪砂は土木材や建材として用いられている。
ここで、鉄含有のガーネットとしては、具体的には鉄ばん柘榴石［Fe３Al２(SiO４)３；almandine］又は灰鉄柘榴石[Ca３Fe２(SiO４)３；andradite]等を挙げることができる。
また、珪砂は、主としてSiO２から成るが、鉄成分も含まれているため、多層カーボンナノチューブの触媒として使用できるものと考えられる。
かかる鉄含有の鉱物の鉱物は、粉末状として用いる。その粉末程度は、粉末の平均粒径が１ｍｍ以下とすることが好ましい。
In the present invention, it is important to use iron-containing mineral powder as a catalyst. These iron-containing minerals include iron-containing garnet, iron-containing olivine, iron-containing spinel, iron-containing pyroxene, marcasite, pyrite, titanite, iron barite, ferromanganese barite, gilespyite, magnetism Examples include earth ore and iron-containing quartz sand. These minerals are widely used for iron-making raw materials, earth and lumber, abrasives, etc., and high-quality, constant composition and crystal structures can be obtained at low cost.
These iron-containing mineral powders may be derived from naturally occurring minerals or may be derived from artificially synthesized minerals.
In particular, among such iron-containing mineral powders, iron-containing garnet and silica sand can be suitably used. Industrially, garnet is used as an abrasive, and silica sand is used as earthwork or building material.
Here, as iron-containing garnet, specifically, iron agate meteorite [Fe 3 Al 2 (SiO 4 ) 3 ; almandine] or ash iron meteorite [Ca 3 Fe 2 (SiO 4 ) 3 ; andradite] or the like Can be mentioned.
Silica sand is mainly composed of SiO 2 , but also contains an iron component, so it can be used as a catalyst for multi-walled carbon nanotubes.
Such an iron-containing mineral is used as a powder. It is preferable that the powder has an average particle size of 1 mm or less.
この様に、粉末状とした鉄含有の鉱物粉末は、図１に示す様に、アルミナボート等の載置台１０の一面側に散布する。この散布は、鉱物粉末を載置台１０の一面側に直接散布してもよく、鉱物粉末を分散した水等の溶媒を載置台１０の一面側に散布した後、溶媒を蒸発させてもよい。
粉末状とした鉄含有の鉱物粉末１２が一面側に散布された載置台１０を加熱管１４内に挿入して載置した後、電気炉１６内に加熱管１４ごと挿入する。次いで、電気炉１６によって加熱管１４を所定温度に加熱しつつ、加熱管１４の一方側から炭素源気体としてのメタンとキャリアーガスとしてのアルゴン又は水素との混合ガスを導入し、加熱管１４の他方側から混合ガスを抜き出す。
この炭素源気体としては、メタンの他に、エタン、プロパン等の炭化水素、ベンゼン等の芳香族炭化水素、一酸化炭素、メタノール、エタノール等の低級アルコールを用いることができる。かかる炭素源気体とキャリアーガスとの混合ガスは、例えばアルゴンと炭素源気体との混合ガスを所定時間用いた後、水素と炭素源気体との混合ガスに切り換えてもよい。
また、電気炉１６内の温度は、使用した炭素源気体の熱分解温度に応じて調整する。具体的には４００〜１２００℃の範囲内で温度調整を図ることが好ましい。
In this manner, the powdered iron-containing mineral powder is dispersed on one surface side of the mounting table 10 such as an alumina boat as shown in FIG. In this spraying, the mineral powder may be directly sprayed on the one surface side of the mounting table 10, or the solvent may be evaporated after the solvent such as water in which the mineral powder is dispersed is sprayed on the one surface side of the mounting table 10.
After placing the mounting table 10 in which the powdered iron-containing mineral powder 12 is dispersed on one side into the heating tube 14 and placing it, the heating tube 14 is inserted into the electric furnace 16. Next, while heating the heating tube 14 to a predetermined temperature by the electric furnace 16, a mixed gas of methane as a carbon source gas and argon or hydrogen as a carrier gas is introduced from one side of the heating tube 14. The mixed gas is extracted from the other side.
As the carbon source gas, in addition to methane, hydrocarbons such as ethane and propane, aromatic hydrocarbons such as benzene, lower alcohols such as carbon monoxide, methanol, and ethanol can be used. The mixed gas of the carbon source gas and the carrier gas may be switched to a mixed gas of hydrogen and the carbon source gas after using a mixed gas of argon and the carbon source gas for a predetermined time, for example.
Moreover, the temperature in the electric furnace 16 is adjusted according to the thermal decomposition temperature of the used carbon source gas. Specifically, it is preferable to adjust the temperature within a range of 400 to 1200 ° C.
かかる触媒気相成長法によって得られた多層カーボンナノチューブであって、その生成温度（電気炉１６内の温度）を超える温度での高温加熱処理が施されていない、本発明に係る製造方法によって得られた多層カーボンナノチューブ（以下、本発明のas-grown多層カーボンナノチューブと称する）は、その透過型電子顕微鏡写真である図２に示す様に、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の主たる部分が、互いに平行状態の層によって形成されている。
具体的には、図３に示す様に、本発明のas-grown多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の任意の箇所を幅方向に三等分し、その中間部分の幅で且つ多層カーボンナノチューブの長手方向に沿った長さ１０ｎｍの四角形の領域（図３の白線で囲まれた領域）を形成する複数層が互いに平行状態である。
一方、触媒として、フェロセンを用いた従来の多層カーボンナノチューブの製造方法で得たas-grown多層カーボンナノチューブ（以下、従来のas-grown多層カーボンナノチューブと称することがある）は、その透過型電子顕微鏡写真である図４に示す様に、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の大部分は、波状の層によって形成されている。この波状の層は、熱分解炭素被覆層である。
特に、図２及び図３に示す本発明のas-grown多層カーボンナノチューブでは、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の中央部及びその近傍を形成する層が互いに平行状態の層によって形成されている。これに対し、図４に示す従来のas-grown多層カーボンナノチューブでは、その積層部の中央部及びその近傍は波状の層によって形成されており、図２及び図３に示す本発明のas-grown多層カーボンナノチューブとは大きく相違することは明らかである。
It is a multi-walled carbon nanotube obtained by such catalytic vapor phase growth method, and obtained by the production method according to the present invention, which is not subjected to high-temperature heat treatment at a temperature exceeding its production temperature (temperature in the electric furnace 16). The obtained multi-walled carbon nanotube (hereinafter referred to as the as-grown multi-walled carbon nanotube of the present invention) has a hollow portion forming a linear portion of the multi-walled carbon nanotube as shown in FIG. The main part of the surrounding laminated part is formed by layers parallel to each other.
Specifically, as shown in FIG. 3, an arbitrary portion of the laminated portion surrounding the hollow portion forming the linear portion of the as-grown multi-walled carbon nanotube of the present invention is divided into three equal parts in the width direction, and the intermediate portion A plurality of layers forming a rectangular region (region surrounded by a white line in FIG. 3) having a width of 10 nm and a length of 10 nm along the longitudinal direction of the multi-walled carbon nanotubes are in parallel with each other.
On the other hand, an as-grown multi-walled carbon nanotube obtained by a conventional method for producing multi-walled carbon nanotubes using ferrocene as a catalyst (hereinafter sometimes referred to as a conventional as-grown multi-walled carbon nanotube) is a transmission electron microscope. As shown in FIG. 4 which is a photograph, most of the laminated part surrounding the hollow part forming the linear part of the multi-walled carbon nanotube is formed by a wave-like layer. This wavy layer is a pyrolytic carbon coating layer.
In particular, in the as-grown multi-walled carbon nanotube of the present invention shown in FIGS. 2 and 3, the central part of the laminated part surrounding the hollow part forming the linear part of the multi-walled carbon nanotube and the layer forming the vicinity thereof are parallel to each other. It is formed by the layer of. On the other hand, in the conventional as-grown multi-walled carbon nanotube shown in FIG. 4, the central part and the vicinity thereof are formed by a wavy layer, and the as-grown of the present invention shown in FIGS. Clearly, this is very different from multi-walled carbon nanotubes.
触媒としてガーネット等の鉄含有の鉱物粉末を用いた触媒気相成長法によって得られた本発明のas-grown多層カーボンナノチューブと、触媒としてセラミックに鉄を担持した鉄担持触媒を用いた従来の触媒気相成長法によって得られた従来のas-grown多層カーボンナノチューブとの相違については、そのメカニズムは未だ充分に充分に解明されていないが以下のように推察される。
つまり、本発明で用いるガーネット等の鉄含有の鉱物粉末では、鉱物粉末を形成する酸化物結晶中に鉄原子が原子レベルで分散して存在している。このため、ガーネット等の鉄含有の鉱物粉末を触媒として用いる触媒気相成長法では、鉱物粉末中に浸透又は拡散する炭素源ガス又は水素ガスによって鉄原子が還元されて還元鉄から成るクラスターを形成する。かかる還元鉄のクラスターの表面に接触する炭素が層状に積層されて多層カーボンナノチューブを形成する。この還元鉄のクラスターは、鉱物粉末と炭素源ガス又は水素ガスとの接触時間と共に成長し、成長するクラスターの外面に接触する炭素が順次層状に積層される結果、直線状部分を形成する中空部を囲む積層部の主たる部分が、互いに平行状態の層によって形成された多層カーボンナノチューブを得ることができるものと考えられる。
一方、従来の鉄担持触媒では、鉄が表面に散点状に露出しているのみである。このため、かかる従来の触媒として用いる触媒気相成長法では、触媒の表面に露出している鉄が炭素源ガス又は水素ガスによって還元されるのみであり、触媒として作用する部分は限定的である。
このため、所定領域に形成された還元鉄の外面に接触する炭素が順次層状に積層された触媒関与部分（図４に示すＡの部分）の外側に、触媒が関与しないで形成された熱分解炭素被覆層（図４に示すＢの部分）が形成される。
Conventional catalyst using as-grown multi-walled carbon nanotube of the present invention obtained by catalytic vapor phase growth method using iron-containing mineral powder such as garnet as catalyst and iron-supported catalyst having iron supported on ceramic as catalyst Regarding the difference from the conventional as-grown multi-walled carbon nanotubes obtained by the vapor phase growth method, the mechanism has not been sufficiently elucidated yet, but is presumed as follows.
In other words, in iron-containing mineral powders such as garnet used in the present invention, iron atoms are dispersed at the atomic level in oxide crystals forming the mineral powder. For this reason, in the catalytic vapor phase growth method using iron-containing mineral powder such as garnet as a catalyst, iron atoms are reduced by carbon source gas or hydrogen gas that permeates or diffuses into the mineral powder to form clusters composed of reduced iron. To do. Carbon in contact with the surface of the reduced iron cluster is laminated in layers to form multi-walled carbon nanotubes. This reduced iron cluster grows with the contact time between the mineral powder and the carbon source gas or hydrogen gas, and the carbon in contact with the outer surface of the growing cluster is sequentially laminated in layers, resulting in a hollow portion forming a linear portion. It is considered that multi-walled carbon nanotubes can be obtained in which the main portion of the laminated portion surrounding the layers is formed of layers in parallel with each other.
On the other hand, in the conventional iron-supported catalyst, iron is only exposed in the form of dots on the surface. For this reason, in the catalyst vapor phase growth method used as such a conventional catalyst, iron exposed on the surface of the catalyst is only reduced by the carbon source gas or hydrogen gas, and the portion acting as a catalyst is limited. .
For this reason, the thermal decomposition formed without catalyst involvement outside the catalyst participation portion (portion A shown in FIG. 4) in which carbon in contact with the outer surface of the reduced iron formed in a predetermined region is sequentially layered. A carbon coating layer (portion B shown in FIG. 4) is formed.
図２及び図３の本発明のas-grown多層カーボンナノチューブと図４の従来のas-grown多層カーボンナノチューブとのラマンスペクトルを図５に示す。図５において、吸収スペクトルＡが図２及び図３の本発明のas-grown多層カーボンナノチューブの吸収スペクトルを示し、吸収スペクトルＢが図４の従来のas-grown多層カーボンナノチューブの吸収スペクトルを示す。
図５に示す吸収スペクトルでは、その１３００ｃｍ−１付近の吸収ピークＤは、多層カーボンナノチューブを形成する結晶内の欠陥に基づく吸収であり、１６００ｃｍ−１付近の吸収ピークＧは多層カーボンナノチューブを形成する結晶に基づく吸収である。このため、吸収ピークＤと吸収ピークＧとの比（Ｄ／Ｇ）が小さい程、多層カーボンナノチューブの結晶化度が高いことを示す。
FIG. 5 shows Raman spectra of the as-grown multi-walled carbon nanotube of the present invention of FIGS. 2 and 3 and the conventional as-grown multi-walled carbon nanotube of FIG. In FIG. 5, the absorption spectrum A shows the absorption spectrum of the as-grown multi-walled carbon nanotube of the present invention shown in FIGS. 2 and 3, and the absorption spectrum B shows the absorption spectrum of the conventional as-grown multi-walled carbon nanotube of FIG.
In the absorption spectrum shown in FIG. 5, the absorption peak D of near 1300 cm -1 is the absorption based on a defect in the crystal forming a multi-walled carbon nanotubes, the absorption peak G around 1600 cm -1 to form a multi-walled carbon nanotube Absorption based on crystals. For this reason, it shows that the crystallinity degree of a multi-walled carbon nanotube is so high that the ratio (D / G) of the absorption peak D and the absorption peak G is small.
かかる観点から吸収スペクトルＡと吸収スペクトルＢとを比較すると、吸収スペクトルＡの吸収ピークＧは吸収ピークＤよりも高いため、吸収ピークＤと吸収ピークＧとの比（Ｄ／Ｇ）は１未満である。これに対し、吸収スペクトルＢの吸収ピークＧは吸収ピークＤよりも低く、吸収ピークＤと吸収ピークＧとの比（Ｄ／Ｇ）は１以上である。
従って、吸収スペクトルＡを示す図２及び図３の本発明のas-grown多層カーボンナノチューブは、吸収スペクトルＢを示す図４の従来のas-grown多層カーボンナノチューブよりも高結晶化度である。
かかる図２及び図３の本発明のas-grown多層カーボンナノチューブのラマンスペクトルにおいて、吸収ピークＤと吸収ピークＧとの比（Ｄ／Ｇ）が好ましくは０．８以下、更に好ましくは０．５以下、特に好ましくは０．３以下である。
但し、図２及び図３の本発明のas-grown多層カーボンナノチューブよりも更に一層の高結晶化度の多層カーボンナノチューブが必要である場合には、図２及び図３の本発明のas-grown多層カーボンナノチューブに更に加熱処理を施してもよい。この加熱処理は、図４の従来のas-grown多層カーボンナノチューブに施す高温加熱処理よりも簡易化できる。
Comparing the absorption spectrum A and the absorption spectrum B from this point of view, the absorption peak G of the absorption spectrum A is higher than the absorption peak D. Therefore, the ratio (D / G) between the absorption peak D and the absorption peak G is less than 1. is there. On the other hand, the absorption peak G of the absorption spectrum B is lower than the absorption peak D, and the ratio (D / G) between the absorption peak D and the absorption peak G is 1 or more.
Therefore, the as-grown multi-walled carbon nanotubes of the present invention of FIG. 2 and FIG. 3 showing the absorption spectrum A have higher crystallinity than the conventional as-grown multi-walled carbon nanotubes of FIG.
In the Raman spectrum of the as-grown multi-walled carbon nanotube of the present invention shown in FIGS. 2 and 3, the ratio (D / G) of the absorption peak D to the absorption peak G is preferably 0.8 or less, more preferably 0.5. Hereinafter, it is particularly preferably 0.3 or less.
However, when a multi-walled carbon nanotube having higher crystallinity than the as-grown multi-walled carbon nanotube of the present invention of FIGS. 2 and 3 is required, the as-grown of the present invention of FIGS. The multi-walled carbon nanotube may be further subjected to a heat treatment. This heat treatment can be simplified more than the high temperature heat treatment applied to the conventional as-grown multi-walled carbon nanotube of FIG.
以上の説明では、図１に示す様に、粉末状とした鉄含有の鉱物粉末１２が一面側に散布された載置台１０を加熱管１４内に挿入して載置した後、電気炉１６内に加熱管１４ごと挿入し、次いで、電気炉１６によって加熱管１４を所定温度に加熱しつつ、加熱管１４の一方側から炭素源気体としてのメタンとキャリアーガスとしてのアルゴン又は水素との混合ガスを導入している。
ここで、触媒として用いる鉄含有の鉱物粉末１２に加熱処理を施した後、加熱処理を施した鉄含有の鉱物粉末１２が載置された加熱管１４に炭素源気体としてのメタンとキャリアーガスとしてのアルゴン又は水素との混合ガスを導入することによって、触媒単位重量当たりの多層カーボンナノチューブの収量を増大できる。
この鉄含有の鉱物粉末１２に施す加熱処理としては、温度が５００〜１５００℃の酸化雰囲気中（空気中）又は採用する加熱温度下で化学的に不活性な不活性ガス雰囲気中（窒素ガスやアルゴンガス中）で触媒として用いる鉄含有の鉱物粉末１２に加熱処理を施すことが好ましい。
また、かかる加熱処理は、加熱管１４に挿入する前に予め粉末状とした鉄含有の鉱物粉末１２に施してもよい。或いは、粉末状とした鉄含有の鉱物粉末１２が一面側に散布された載置台１０を加熱管１４内に挿入して載置した後、電気炉１６内に加熱管１４ごと挿入し、次いで、電気炉１６によって加熱管１４を所定温度に加熱しつつ、加熱管１４の一方側から空気、アルゴンガス又は窒素ガスを導入して施してもよい。
尚、図１に示す様に、鉱物粉末１２が一面側に散布された載置台１０を加熱管１４内に挿入して載置し、鉱物粉末を静置した状態で所定温度に加熱しつつ、炭素源気体とキャリアーガスとの混合ガスを導入して多層カーボンナノチューブを製造していたが、鉱物粉末を炭素源気体とキャリアーガスとの混合ガスで浮遊させて多層カーボンナノチューブを製造してもよい。
In the above description, as shown in FIG. 1, after placing the mounting table 10 in which the powdered iron-containing mineral powder 12 is dispersed on one side into the heating tube 14 and mounting it, Then, the heating tube 14 is inserted into the heating tube 14, and then the heating tube 14 is heated to a predetermined temperature by the electric furnace 16, and a mixed gas of methane as the carbon source gas and argon or hydrogen as the carrier gas from one side of the heating tube 14. Has been introduced.
Here, after heat-treating the iron-containing mineral powder 12 used as a catalyst, the heating tube 14 on which the heat-treated iron-containing mineral powder 12 is placed as methane and a carrier gas as a carbon source gas. By introducing a mixed gas of argon or hydrogen, it is possible to increase the yield of multi-walled carbon nanotubes per catalyst unit weight.
The heat treatment applied to the iron-containing mineral powder 12 may be performed in an oxidizing atmosphere (in the air) at a temperature of 500 to 1500 ° C. or in an inert gas atmosphere (nitrogen gas or It is preferable to heat-treat the iron-containing mineral powder 12 used as a catalyst in (in argon gas).
Further, the heat treatment may be performed on the iron-containing mineral powder 12 that has been powdered before being inserted into the heating tube 14. Alternatively, after placing the mounting table 10 on which the iron-containing mineral powder 12 in the form of powder is spread on one side into the heating tube 14 and placing it, the heating tube 14 is inserted into the electric furnace 16, and then Air, argon gas, or nitrogen gas may be introduced from one side of the heating tube 14 while the heating tube 14 is heated to a predetermined temperature by the electric furnace 16.
In addition, as shown in FIG. 1, the mounting table 10 in which the mineral powder 12 is dispersed on one side is inserted and placed in the heating tube 14, and the mineral powder is left standing and heated to a predetermined temperature, Multi-walled carbon nanotubes were produced by introducing a mixed gas of a carbon source gas and a carrier gas. However, multi-walled carbon nanotubes may be produced by suspending mineral powder in a mixed gas of a carbon source gas and a carrier gas. .
触媒として、下記表１に示す組成のガーネット粉末［宇部サンド工業（株）製BARTON GARNET(商品名)］を用いた。この組成は、Ｘ線マイクロアナライザー（ＥＰＭＡ）を用いて測定した値である。また、ガーネット粉末の平均粒径は約０．１ｍｍであった。 As the catalyst, garnet powder [BARTON GARNET (trade name) manufactured by Ube Sand Industries, Ltd.] having the composition shown in Table 1 below was used. This composition is a value measured using an X-ray microanalyzer (EPMA). The average particle size of the garnet powder was about 0.1 mm.
先ず、電気炉１６によって加熱管１４を８５０℃に加熱して、加熱管１４の一方側からメタン（３００ｍｌ／分）とキャリアーガスとしてのアルゴン（１００ｍｌ／分）との混合ガスを導入し、加熱管１４の他方側から混合ガスを抜き出す。この８５０℃での加熱処理を３０分間行った。
次いで、加熱管１４を冷却して、アルミナボート１０を取り出し、ガーネット粉末の粒子表面に黒色の針状体が成長していた。この黒色の針状体が、その生成温度を超える温度での高温加熱処理が施されていないas-grown多層カーボンナノチューブである。
First, the heating tube 14 is heated to 850 ° C. by the electric furnace 16, and a mixed gas of methane (300 ml / min) and argon (100 ml / min) as a carrier gas is introduced from one side of the heating tube 14 and heated. The mixed gas is extracted from the other side of the tube 14. This heat treatment at 850 ° C. was performed for 30 minutes.
Next, the heating tube 14 was cooled, the alumina boat 10 was taken out, and black needles were growing on the surface of the garnet powder particles. This black needle-like body is an as-grown multi-walled carbon nanotube that has not been subjected to high-temperature heat treatment at a temperature exceeding its generation temperature.
かかるas-grown多層カーボンナノチューブの透過型電子顕微鏡写真を図２に示す。図２に示す多層カーボンナノチューブは、その直線状部分を形成する中空部を囲む積層部の殆どの部分が、互いに平行状態の層によって形成されている。このため、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の中央部及びその近傍が、互いに平行状態の層によって形成されている。また、図３に示す様に、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の任意の箇所を三等分したうち、その中間部分の幅で且つ多層カーボンナノチューブの長手方向に沿った長さ１０ｎｍの四角形の領域（図３に白線で示す四角形の領域）を形成する複数層が互いに平行状態でもある。 A transmission electron micrograph of such as-grown multi-walled carbon nanotubes is shown in FIG. In the multi-walled carbon nanotube shown in FIG. 2, most of the laminated part surrounding the hollow part forming the linear part is formed by layers in parallel with each other. For this reason, the center part of the lamination | stacking part surrounding the hollow part which forms the linear part of a multilayer carbon nanotube, and its vicinity are formed of the mutually parallel layer. In addition, as shown in FIG. 3, an arbitrary portion of the laminated portion surrounding the hollow portion forming the linear portion of the multi-walled carbon nanotube is divided into three equal parts, and the width of the intermediate portion and in the longitudinal direction of the multi-walled carbon nanotube A plurality of layers forming a 10 nm long rectangular region (a rectangular region indicated by a white line in FIG. 3) are also in parallel with each other.
実施例１において、電気炉１６によって加熱管１４を８５０℃に加熱しつつ、加熱管１４の一方側からメタン（３００ｍｌ／分）とキャリアーガスとしてのアルゴン（１００ｍｌ／分）との混合ガスを導入することに代えて、加熱管１４を９５０℃に加熱しつつ、加熱管１４の一方側からメタン（３００ｍｌ／分）とキャリアーガスとしての水素（２００ｍｌ／分）との混合ガスを導入し、加熱管１４の他方側から混合ガスを抜き出す。この９５０℃での加熱処理を１０分間行った他は、実施例１と同様にしてas-grown多層カーボンナノチューブを得た。得られたas-grown多層カーボンナノチューブの透過型電子顕微鏡写真は、図２に示すものと略同一であって、その直線状部分を形成する中空部を囲む積層部の殆どの部分が、互いに平行状態の層によって形成されている。このため、多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の中央部及びその近傍が、互いに平行状態の層によって形成されている。 In Example 1, a mixed gas of methane (300 ml / min) and argon as a carrier gas (100 ml / min) was introduced from one side of the heating tube 14 while the heating tube 14 was heated to 850 ° C. by the electric furnace 16. Instead of heating, while heating the heating tube 14 to 950 ° C., a mixed gas of methane (300 ml / min) and hydrogen as a carrier gas (200 ml / min) is introduced from one side of the heating tube 14 and heated. The mixed gas is extracted from the other side of the tube 14. As-grown multi-walled carbon nanotubes were obtained in the same manner as in Example 1 except that the heat treatment at 950 ° C. was performed for 10 minutes. The transmission electron micrograph of the obtained as-grown multi-walled carbon nanotube is almost the same as that shown in FIG. 2, and most of the laminated part surrounding the hollow part forming the linear part is parallel to each other. It is formed by a state layer. For this reason, the center part of the lamination | stacking part surrounding the hollow part which forms the linear part of a multilayer carbon nanotube, and its vicinity are formed of the mutually parallel layer.
縦型加熱炉（内径１７．０ｃｍ，長さ１５０ｃｍ）の頂部に、スプレーノズルを取り付ける。加熱炉の炉内温度を１２００℃に昇温・維持し、スプレーノズルから４wt％のフェロセンを含有するベンゼンの液体原料２０ｇ／分を１００リットル／分の水素ガスの流量で炉壁に直接噴霧（スプレー）散布するように供給する。このような条件の下で、フェロセンは熱分解して鉄微粒子を作り、これがシード（種）となってベンゼンの熱分解による炭素によって多層カーボンナノチューブを成長させてas-grown多層カーボンナノチューブを得た。得られたas-grown多層カーボンナノチューブの透過型電子顕微鏡写真を図４に示す。図４に示す透過型電子顕微鏡写真では、その中空部を囲む積層部の大部分は波状の層によって形成されている。このため、図４に示すas-grown多層カーボンナノチューブでは、その積層部の内周面側の数層が層状に積層されているものの、積層部の中央部及びその近傍は波状の層（熱分解炭素被覆層）によって形成されており、その積層部の任意の箇所を三等分したうち、その中間部分の幅で且つ多層カーボンナノチューブの長手方向に沿った長さ１０ｎｍの四角形の領域も波状の層によって形成されている。 A spray nozzle is attached to the top of a vertical heating furnace (inner diameter 17.0 cm, length 150 cm). The furnace temperature in the heating furnace was raised and maintained at 1200 ° C., and 20 g / min of benzene containing 4 wt% ferrocene was sprayed directly from the spray nozzle onto the furnace wall at a hydrogen gas flow rate of 100 liters / min ( Spray) Supply to spray. Under these conditions, ferrocene was pyrolyzed to produce iron fine particles, which became seeds and grew multi-walled carbon nanotubes by carbon from the thermal decomposition of benzene to obtain as-grown multi-walled carbon nanotubes. . A transmission electron micrograph of the obtained as-grown multi-walled carbon nanotube is shown in FIG. In the transmission electron micrograph shown in FIG. 4, most of the laminated portion surrounding the hollow portion is formed by a wavy layer. For this reason, in the as-grown multi-walled carbon nanotube shown in FIG. 4, several layers on the inner peripheral surface side of the laminated portion are laminated in layers, but the central portion of the laminated portion and the vicinity thereof are wavy layers (thermal decomposition). A rectangular region having a width of the intermediate portion and a length of 10 nm along the longitudinal direction of the multi-walled carbon nanotube is obtained by dividing the arbitrary portion of the laminated portion into three equal parts. Formed by layers.
実施例１及び比較例２で得られた多層カーボンナノチューブについてのラマンスペクトルを図５に示す。図５に示すラマンスペクトルのうち、吸収スペクトルＡが実施例１で得たas-grown多層カーボンナノチューブの吸収スペクトルを示し、吸収スペクトルＢが比較例１で得たas-grown多層カーボンナノチューブの吸収スペクトルを示す。
図５に示す吸収スペクトルＡと吸収スペクトルＢとを比較すると、吸収スペクトルＡの吸収ピークＧは吸収ピークＤよりも高いため、吸収ピークＤと吸収ピークＧとの比（Ｄ／Ｇ）は０．５１未満である。これに対し、吸収スペクトルＢの吸収ピークＧは吸収ピークＤよりも低く、吸収ピークＤと吸収ピークＧとの比（Ｄ／Ｇ）は１．２２である。
従って、吸収スペクトルＡを示す実施例１のas-grown多層カーボンナノチューブは、吸収スペクトルＢを示す比較例１のas-grown多層カーボンナノチューブよりも高結晶化度である。
FIG. 5 shows Raman spectra of the multi-walled carbon nanotubes obtained in Example 1 and Comparative Example 2. Among the Raman spectra shown in FIG. 5, the absorption spectrum A shows the absorption spectrum of the as-grown multi-walled carbon nanotube obtained in Example 1, and the absorption spectrum B shows the absorption spectrum of the as-grown multi-walled carbon nanotube obtained in Comparative Example 1. Indicates.
When the absorption spectrum A and the absorption spectrum B shown in FIG. 5 are compared, the absorption peak G of the absorption spectrum A is higher than the absorption peak D. Therefore, the ratio (D / G) of the absorption peak D to the absorption peak G is 0. It is less than 51. On the other hand, the absorption peak G of the absorption spectrum B is lower than the absorption peak D, and the ratio (D / G) between the absorption peak D and the absorption peak G is 1.22.
Therefore, the as-grown multi-walled carbon nanotube of Example 1 showing the absorption spectrum A has a higher crystallinity than the as-grown multi-walled carbon nanotube of Comparative Example 1 showing the absorption spectrum B.
実施例１において、触媒として、ガーネット粉末に代えて、粒径が約０．１ｍｍ程度の珪砂（宇部サンド株式会社製、鉄の含有量；Fe２O３換算で約１重量％）を用いた他は、実施例１と同様にしてas-grown多層カーボンナノチューブを得た。得られたas-grown多層カーボンナノチューブの透過型電子顕微鏡写真を図６に示す。図６に示す透過型電子顕微鏡写真では、図２に示す実施例１のas-grown多層カーボンナノチューブの透過型電子顕微鏡写真と同様に、その直線状部分を形成する中空部を囲む側壁部の殆どの部分が、互いに平行状態の層によって形成されている。 In Example 1, instead of garnet powder, silica sand having a particle size of about 0.1 mm (manufactured by Ube Sand Co., Ltd., iron content; about 1% by weight in terms of Fe 2 O 3 ) was used as the catalyst. Otherwise, as-grown multi-walled carbon nanotubes were obtained in the same manner as in Example 1. A transmission electron micrograph of the obtained as-grown multi-walled carbon nanotube is shown in FIG. In the transmission electron micrograph shown in FIG. 6, as in the transmission electron micrograph of the as-grown multi-walled carbon nanotube of Example 1 shown in FIG. 2, most of the side wall portion surrounding the hollow portion forming the linear portion is obtained. Are formed by layers parallel to each other.
実施例１において、ガーネット粉末に、大気中で１０００℃の加熱雰囲気中で約６時間の加熱処理を施した後、加熱処理を施したガーネット粉末を触媒に用いて実施例１と同様にしてas-grown多層カーボンナノチューブを得た。
本実施例で得られたas-grown多層カーボンナノチューブの収量は、実施例１で得られたas-grown多層カーボンナノチューブの約１０倍であった。
尚、得られたas-grown多層カーボンナノチューブの透過型電子顕微鏡写真は、図２に示すものと同一であった。
In Example 1, the garnet powder was subjected to heat treatment in the atmosphere at 1000 ° C. for about 6 hours, and then the heat-treated garnet powder was used as a catalyst in the same manner as in Example 1. -grown multi-walled carbon nanotubes were obtained.
The yield of the as-grown multi-walled carbon nanotubes obtained in this example was about 10 times that of the as-grown multi-walled carbon nanotubes obtained in Example 1.
The obtained transmission electron micrograph of the as-grown multi-walled carbon nanotube was the same as that shown in FIG.
１０ 載置台
１２ 鉱物粉末
１４ 加熱管
１６ 電気炉
10 mounting table 12 mineral powder 14 heating tube 16 electric furnace
Claims (7)
前記触媒として、鉄含有の鉱物粉末を用いることを特徴とする多層カーボンナノチューブの製造方法。 When a multi-walled carbon nanotube is produced by a catalytic vapor phase growth method in which a multi-walled carbon nanotube is grown from the surface of the catalyst by circulating a carbon source gas in a heated atmosphere in which a catalyst is present and maintained at a predetermined temperature,
A method for producing a multi-walled carbon nanotube, wherein iron-containing mineral powder is used as the catalyst.
前記多層カーボンナノチューブの透過型電子顕微鏡写真において、前記多層カーボンナノチューブの直線状部分を形成する中空部を囲む積層部の主たる部分が、互いに平行状態の層によって形成されていることを特徴とする多層カーボンナノチューブ。 A multilayer obtained by a catalyst vapor phase growth method in which a carbon source gas is circulated in a heated atmosphere in which a catalyst is present and maintained at a predetermined temperature, and is not subjected to high-temperature heat treatment at a high temperature exceeding the temperature of the heated atmosphere A carbon nanotube,
In the transmission electron micrograph of the multi-walled carbon nanotube, the multi-layer carbon nanotube is characterized in that the main part of the laminated part surrounding the hollow part forming the linear part of the multi-walled carbon nanotube is formed by layers parallel to each other. carbon nanotube.
前記多層カーボンナノチューブのラマンスペクトルが、その１３００ｃｍ−１付近の吸収ピークＤと１６００ｃｍ−１付近の吸収ピークＧとの比（Ｄ／Ｇ）が０．８以下であることを特徴とする多層カーボンナノチューブ。 Multilayer carbon obtained by a catalyst vapor phase growth method in which a carbon source gas is circulated in a heated atmosphere in which a catalyst is present and maintained at a predetermined temperature, and is not subjected to a high-temperature heat treatment at a temperature exceeding the temperature of the heated atmosphere Nanotubes,
Multi-wall carbon nanotubes Raman spectrum of the multi-walled carbon nanotubes, the ratio of the absorption peak G in the vicinity of the absorption peak D and 1600 cm -1 in the vicinity of the 1300 cm -1 (D / G) is equal to or not more than 0.8 .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007139596A JP4660705B2 (en) | 2007-05-25 | 2007-05-25 | Method for producing multi-walled carbon nanotube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007139596A JP4660705B2 (en) | 2007-05-25 | 2007-05-25 | Method for producing multi-walled carbon nanotube |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JP2008290918A true JP2008290918A (en) | 2008-12-04 |
| JP2008290918A5 JP2008290918A5 (en) | 2010-08-05 |
| JP4660705B2 JP4660705B2 (en) | 2011-03-30 |
Family
ID=40166043
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2007139596A Expired - Fee Related JP4660705B2 (en) | 2007-05-25 | 2007-05-25 | Method for producing multi-walled carbon nanotube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4660705B2 (en) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52103528A (en) * | 1976-02-25 | 1977-08-30 | Showa Denko Kk | Manufacture of carbon fibers by gas phase reaction |
| JPS62242B2 (en) * | 1982-04-10 | 1987-01-07 | Morinobu Endo | |
| JP2003206117A (en) * | 2002-01-15 | 2003-07-22 | Centre National De La Recherche Scientifique (Cnrs) | Process for mass production of multiwalled carbon nanotubes |
| JP2004168647A (en) * | 2002-10-30 | 2004-06-17 | Mitsubishi Corp | Method and apparatus for manufacturing multilayer carbon nanotube and method of refining the same and pulse like high voltage large current power source |
| JP2004182548A (en) * | 2002-12-04 | 2004-07-02 | National Institute Of Advanced Industrial & Technology | Method of manufacturing carbon nanotube |
| JP2005263607A (en) * | 2004-03-22 | 2005-09-29 | Univ Shinshu | Cnt surface modification method and cnt |
| JP2005272261A (en) * | 2004-03-26 | 2005-10-06 | Toray Ind Inc | Method for producing carbon nanotube |
| JP2006232643A (en) * | 2005-02-28 | 2006-09-07 | Univ Meijo | Method for manufacturing carbon nanotube |
| JP2007290928A (en) * | 2006-04-26 | 2007-11-08 | Kyushu Institute Of Technology | String-like carbon, method of utilizing the same and method of manufacturing the same |
-
2007
- 2007-05-25 JP JP2007139596A patent/JP4660705B2/en not_active Expired - Fee Related
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52103528A (en) * | 1976-02-25 | 1977-08-30 | Showa Denko Kk | Manufacture of carbon fibers by gas phase reaction |
| JPS62242B2 (en) * | 1982-04-10 | 1987-01-07 | Morinobu Endo | |
| JP2003206117A (en) * | 2002-01-15 | 2003-07-22 | Centre National De La Recherche Scientifique (Cnrs) | Process for mass production of multiwalled carbon nanotubes |
| JP2004168647A (en) * | 2002-10-30 | 2004-06-17 | Mitsubishi Corp | Method and apparatus for manufacturing multilayer carbon nanotube and method of refining the same and pulse like high voltage large current power source |
| JP2004182548A (en) * | 2002-12-04 | 2004-07-02 | National Institute Of Advanced Industrial & Technology | Method of manufacturing carbon nanotube |
| JP2005263607A (en) * | 2004-03-22 | 2005-09-29 | Univ Shinshu | Cnt surface modification method and cnt |
| JP2005272261A (en) * | 2004-03-26 | 2005-10-06 | Toray Ind Inc | Method for producing carbon nanotube |
| JP2006232643A (en) * | 2005-02-28 | 2006-09-07 | Univ Meijo | Method for manufacturing carbon nanotube |
| JP2007290928A (en) * | 2006-04-26 | 2007-11-08 | Kyushu Institute Of Technology | String-like carbon, method of utilizing the same and method of manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4660705B2 (en) | 2011-03-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101680412B1 (en) | Method for producing aligned carbon nanotube aggregate | |
| Hong et al. | Controlling the growth of single-walled carbon nanotubes on surfaces using metal and non-metal catalysts | |
| KR102307337B1 (en) | boron nitride nanotubes and process for production thereof | |
| Hoyos-Palacio et al. | Catalytic effect of Fe, Ni, Co and Mo on the CNTs production | |
| JP2016164122A (en) | Synthesis of high-quality carbon single-walled nanotube | |
| Torres et al. | Unzipping of multi-wall carbon nanotubes with different diameter distributions: Effect on few-layer graphene oxide obtention | |
| US8835006B2 (en) | Carbon nanohorn carried material and process for producing carbon nanotube | |
| JP2010137222A (en) | Metal nano catalyst, manufacturing method therefor, and adjusting method of growth mode of carbon nanotube using therewith | |
| JP2008529957A (en) | Single-walled carbon nanotube catalyst | |
| Xu et al. | Synthesis and characterization of high purity GaN nanowires | |
| Kim et al. | Amorphous gallium oxide nanowires synthesized by metalorganic chemical vapor deposition | |
| CN110255626A (en) | Method based on vapor deposition preparation surface-active onion shape Nano carbon balls | |
| WO2012057229A1 (en) | Process for production of carbon nanotubes | |
| JP7086418B2 (en) | Manufacturing method of carbon nanotubes | |
| Huang et al. | Nanostructures of mixed-phase boron nitride via biased microwave plasma-assisted CVD | |
| Donato et al. | Influence of carbon source and Fe-catalyst support on the growth of multi-walled carbon nanotubes | |
| KR101357630B1 (en) | Supported Catalyst for Synthesizing Carbon Nanotubes and Method for Preparing thereof | |
| Zhi et al. | Boron carbonitride nanotubes | |
| JP4660705B2 (en) | Method for producing multi-walled carbon nanotube | |
| JP2010018498A (en) | Method for manufacturing carbon nanotube, and carbon nanotube | |
| KR20120092344A (en) | Fabrication method of carbon nanotube or carbon nanofiber using metal-organic frameworks, and the carbon nanotube or carbon nanofiber thereby | |
| JP2005279624A (en) | Catalyst, method and apparatus for producing carbon nanotube | |
| JP2002105765A (en) | Carbon nanofiber compound and method for producing carbon nanofiber | |
| JP5196417B2 (en) | Catalyst for producing carbon nanocoil and method for producing carbon nanocoil | |
| Qian et al. | Inverted SiC nanoneedles grown on carbon fibers by a two-crucible method without catalyst |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20100525 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20100621 |
|
| A871 | Explanation of circumstances concerning accelerated examination |
Free format text: JAPANESE INTERMEDIATE CODE: A871 Effective date: 20100621 |
|
| A975 | Report on accelerated examination |
Free format text: JAPANESE INTERMEDIATE CODE: A971005 Effective date: 20100729 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20100810 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20101005 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20101102 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20101202 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140114 Year of fee payment: 3 |
|
| LAPS | Cancellation because of no payment of annual fees |