JP3826281B2 - Cobalt compound-encapsulating carbon composite and method for producing the same - Google Patents

Description

【０１２９】
内包物について、鮮明な電子回折パターンが観測されており、内包物は高い結晶性を有していた。TEM観察の結果、内包物の結晶化率（炭化コバルトが充填されている範囲のTEM像の面積に対する、結晶性炭化コバルトのTEM像の面積の割合）は、約１００％であった。
【０１３０】
本実施例１で得られた炭素質材料においてはその炭素壁面が、入れ子状でもスクロール状でもなく、パッチワーク状（いわゆる paper mache 状ないし張り子状）になっているように見え、ナノフレークカーボンチューブであった。
【０１３１】
本実施例で得られたコバルト又はコバルト合金内包炭素複合体を構成しているナノフレークカーボンチューブの形状は、円筒状であり、その長手方向を横切る断面のTEM写真において観察されるグラフェンシート像は、閉じた環状ではなく、不連続点を多数有する不連続な環状であった。
【０１３２】
また、本発明のコバルト又はコバルト合金内包炭素複合体を構成しているナノフレークカーボンチューブをTEM観察した場合において、その長手方向に配向している多数の略直線状のグラフェンシート像に関し、個々のグラフェンシート像の長さは、概ね２〜３０nmの範囲であった。
【０１３３】
実施例２
図１に示すような反応装置を使用し、次のようにして本発明のコバルト又はコバルト合金内包炭素複合体を得た。
【０１３４】
工程 (1)
ＣｏＣｌ₂・４Ｈ₂Ｏ（関東化学株式会社製）０．２ｇをニッケルボート内に薄く広げて敷き詰める。これを石英管からなる炉内中央に設置し、炉内を圧力50Paまで減圧する。このとき、真空吸引するラインを取り付けた反応炉端部とは反対側（図１の反応管の左側）から酸素5000ppm含有アルゴンガスを10ml／minの速度で供給する。これにより、反応炉の内容積をＡ（リッル）とし、酸素量をＢ（Ｎcc）とした場合の比Ｂ／Ａを、６×１０^-3とした。次いで、反応温度1000℃まで減圧のまま昇温する。
【０１３５】
工程 (2)
1000℃に到達した時点で、アルゴンを導入し、圧力を６．７×１０⁴Paに制御する。一方、熱分解性炭素源として、ベンゼン槽にアルゴンガスをバブリングさせて、揮発したベンゼンとアルゴンの混合ガスを、反応炉容積１リットル当たり、60ml／minの流速で炉内に導入し、希釈ガスとして、アルゴンガスを40ml／minの流速で導入する。
【０１３６】
1000℃の反応温度で90分間反応させることにより、500℃まで20分で降温後、ヒーターを取り外して20分で室温まで空冷することで本発明のコバルト又はコバルト合金内包炭素複合体を含む炭素質材料を200ｍｇ得た。
【０１３７】
SEM観察の結果から、得られた炭素質材料を構成するコバルト又はコバルト合金内包炭素複合体は、直径20〜40nm、長さ3〜5ミクロンで直線性の高いものであった。また、炭素からなる壁部の厚さは、２〜１０nmであり、全長に亘って実質的に均一であった。また、該壁部は、TEM観察及びＸ線回折法から、炭素網面間の平均距離（ｄ002）が0.34nm以下の黒鉛質構造を有するナノフレークカーボンチューブであることを確認した。
【０１３８】
上記本発明の炭素質材料を構成する多数のコバルト又はコバルト合金内包炭素複合体を電子顕微鏡（TEM）で観察したところ、ナノフレークカーボンチューブの空間部（ナノフレークカーボンチューブのチューブ壁で囲まれた空間）への充填率が１０〜８０％の範囲の種々の充填率を有するコバルト又はコバルト合金内包炭素複合体が混在していた。
【０１３９】
TEM観察の結果から、本発明のコバルト又はコバルト合金内包炭素複合体を含む炭素質材料において、ナノフレークカーボンチューブ内空間部への平均充填率は４５％（炭素質材料としての平均値）であった。また、実施例１と同様にしてＸ線回折から算出されたＲ値は、０．４８であった。
【０１４０】
内包物について、鮮明な電子回折パターンが観測されており、内包物が高い結晶性を有することが分かった。TEM観察の結果、内包物の結晶化率は、約１００％であった。
【０１４１】
本実施例で得られたコバルト又はコバルト合金内包炭素複合体を構成しているナノフレークカーボンチューブの形状は、円筒状であり、その長手方向を横切る断面のTEM写真において観察されるグラフェンシート像は、閉じた環状ではなく、不連続点を多数有する不連続な環状であった。
【０１４２】
また、本発明のコバルト又はコバルト合金内包炭素複合体を構成しているナノフレークカーボンチューブをTEM観察した場合において、その長手方向に配向している多数の略直線状のグラフェンシート像に関し、個々のグラフェンシート像の長さは、概ね２〜３０nmの範囲であった。
【０１４３】
実施例３
図２に示すような装置を用い、次の工程(1)及び(2)を行って本発明のコバルト又はコバルト合金内包炭素複合体を得た。
【０１４４】
工程 (1)
無水CoCl₂（関東化学株式会社製）0.2ｇを磁製ボート内に薄く広げて敷き詰める。これを炉内下流側に設置する。また、磁製ボートに入れたジシクロペンタジエニルコバルトを炉内上流側に設置する。
【０１４５】
炉内を圧力50Paまで減圧する。このとき、真空吸引するラインの反対側から酸素5000ppm含有アルゴンガスを50ml／minの速度で供給する。これにより、反応炉容積をＡ（リットル）とし、酸素量をＢ（Ｎcc）とした場合の比Ｂ／Ａを、６×１０^-3とした。次いで、反応温度1000℃まで減圧のまま昇温する。
【０１４６】
工程 (2)
反応温度1000℃に到達した時点で、アルゴンを導入し、圧力を６．７×１０⁴Paに制御する。一方、炉内上流側に設置した磁製ボート中のジシクロペンタジエニルコバルトを、200℃まで圧力を６．７×１０⁴Paに維持して昇温する。
【０１４７】
また、熱分解性炭素源として、ベンゼン槽にアルゴンガスをバブリングさせて、揮発したベンゼンとアルゴンの混合ガスを、反応炉容積１リットル当たり、60ml／minの流速で炉内に導入し、希釈ガスとして、アルゴンガスを40ml／minの流速で導入する。1000℃の反応温度で90分間反応させた。
【０１４８】
次いで、500℃まで20分で降温後、ヒーターを取り外して20分で室温まで空冷することにより、コバルト又はコバルト合金内包炭素複合体を含む炭素質材料を、反応管内に400mg得た。
【０１４９】
SEM観察の結果から、得られたコバルト又はコバルト合金内包炭素複合体は、直径20〜40nm、長さ3〜5ミクロンで直線性の高いものであった。
【０１５０】
また、炭素からなる壁部の厚さは、５〜１５nmであり、全長に亘って実質的に均一であった。また、該壁部は、TEM観察及びＸ線回折法から炭素網面間の平均距離（ｄ002）が0.34nm以下の黒鉛質構造を有するナノフレークカーボンチューブであることを確認した。
【０１５１】
上記本発明の炭素質材料を構成する多数のコバルト又はコバルト合金内包炭素複合体を電子顕微鏡(TEM)で観察したところ、ナノフレークカーボンチューブの空間部（ナノフレークカーボンチューブの炭素壁で囲まれた空間）への充填率が２５〜９０％の範囲の種々の充填率を有するコバルト又はコバルト合金内包炭素複合体が混在していた。
【０１５２】
内包物について鮮明な電子回折パターンが観測され、内包物は高い結晶性を有していた。TEM観察の結果、内包物の結晶化率は、約１００％であった。
【０１５３】
TEM観察の結果から、本発明のコバルト又はコバルト合金内包炭素複合体を含む炭素質材料において、ナノフレークカーボンチューブ内空間部への平均充填率（炭素質材料としての平均値）は７０％であった。また、実施例１と同様にしてＸ線回折から算出されたＲ値は、３．５であった。
【０１５４】
本実施例で得られたコバルト又はコバルト合金内包炭素複合体を構成しているナノフレークカーボンチューブの形状は、円筒状であり、その長手方向を横切る断面のTEM写真において観察されるグラフェンシート像は、閉じた環状ではなく、不連続点を多数有する不連続な環状であった。
【０１５５】
また、本発明のコバルト又はコバルト合金内包炭素複合体を構成しているナノフレークカーボンチューブをTEM観察した場合において、その長手方向に配向している多数の略直線状のグラフェンシート像に関し、個々のグラフェンシート像の長さは、概ね２〜３０nmの範囲であった。
【０１５６】
実施例４
図１に示すような反応装置において、反応管をカーボン製として耐熱性を高めて使用し、次のようにして本発明のコバルト又はコバルト合金内包炭素複合体を得た。
【０１５７】
工程 (1)
無水ＣｏＣｌ₂（関東化学株式会社製）0.2ｇを磁製ボート内に薄く広げて敷き詰める。これを石英管からなる炉内中央に設置し、炉内を圧力50Paまで減圧する。このとき、真空吸引するラインの反対側から酸素5000ppm含有アルゴンガスを5ml／minの速度で供給する。これにより、反応炉の内容積をＡ（リットル）とし、酸素量をＢ（Ｎcc）とした場合の比Ｂ／Ａを、２．５×１０^-3とした。次いで、反応温度1000℃まで減圧のまま昇温する。
【０１５８】
工程 (2)
1000℃に到達した時点で、アルゴンを導入し、圧力を６．７×１０⁴Paに制御する。一方、熱分解性炭素源として、ベンゼン槽にアルゴンガスをバブリングさせて、揮発したベンゼンとアルゴンの混合ガスを、反応炉容積１リットル当たり、30ml／minの流速で炉内に導入し、希釈ガスとして、アルゴンガスを20ml／minの流速で導入する。
【０１５９】
1000℃の反応温度で120分間反応させた後、1000℃のまま圧力50Paまで減圧する。その後、アルゴン雰囲気で9.0×10⁴Paにし、炉内を、1400℃まで120分で昇温後、1400℃で6時間維持し、500℃まで24時間で冷却し、ヒーターを取り外して室温まで放冷することで本発明のコバルト又はコバルト合金内包炭素複合体を含む炭素質材料を１８０ｍｇ得た。
【０１６０】
SEM観察の結果から、得られた炭素質材料を構成するコバルト又はコバルト合金内包炭素複合体は、直径20〜50nm、長さ、2〜5ミクロンで直線性の高いものであった。また、炭素からなる壁部の厚さは、２〜１０nmであり、全長に亘って実質的に均一であった。また、該壁部は、TEM観察及びＸ線回折法から、炭素網面間の平均距離（ｄ002）が0.34nm以下の黒鉛質構造を有する入れ子構造の多層カーボンナノチューブであることを確認した。
【０１６１】
上記本発明の炭素質材料を構成する多数のコバルト又はコバルト合金内包炭素複合体を電子顕微鏡(TEM）で観察したところ、入れ子構造の多層カーボンナノチューブの空間部（入れ子構造の多層カーボンナノチューブのチューブ壁で囲まれた空間）への充填率が１０〜５０％の範囲の種々の充填率を有するコバルト又はコバルト合金内包炭素複合体が混在していた。
【０１６２】
内包物について鮮明な電子回折パターンが観測され、内包物が高い結晶性を有していた。TEM観察の結果、内包物の結晶化率は、約１００％であった。
【０１６３】
TEM観察の結果から、本発明のコバルト又はコバルト合金内包炭素複合体を含む炭素質材料において、入れ子構造の多層カーボンナノチューブ内空間部への平均充填率は２０％（炭素質材料としての平均値）であった。また、実施例１と同様にしてＸ線回折から算出されたＲ値は、０．３８であった。
【０１６４】
【発明の効果】
本発明によれば、以下のような顕著な効果が達成される。
【０１６５】
本発明の製造方法によると、炭素材の壁部で囲まれた空間部の１０〜９０％がコバルト又はコバルト合金により充たされた新規な構成を有するコバルト又はコバルト合金内包炭素複合体を、簡便な手法により高収率でかつ大量に得ることができる。
【０１６６】
得られたコバルト又はコバルト合金内包炭素複合体は、空間部の１０〜９０％にコバルト又はコバルト合金を内包する点において、カーボンナノチューブの先端にコバルトが存在する公知材料とは、構造上明確に相違するものであり、特異な構造に基づく新規な特異な性質を有する新規材料である。
【０１６７】
また、本発明のコバルト又はコバルト合金内包炭素複合体は、耐久性に優れたグラファイト壁で囲まれた空間に金属が内包されているので、特性の劣化を殆ど生じない半永久的な導電体乃至分子導電線、及び、磁性体乃至分子磁石としての機能を備えている。
【０１６８】
従って、本発明によるコバルト又はコバルト合金内包炭素複合体は、電子放出材料、コバルト徐放性材料、磁気記録材料、摺動材料、導電性フィブリル、磁性材料、磁性流動体、超伝導材料、耐摩耗性材料、半導体材料などとして、極めて有用である。
【０１６９】
また、本発明では、内包物であるコバルト又はコバルト合金によりカーボンチューブ内空間部の全体が充填されているのではなく、該空間部の１０〜９０％が充填されているので製造が容易であり、カーボンナノチューブ単独からなる材料に比べて電気伝導度が高く、磁性も付与でき、その他ナノサイズの量子効果が期待できる点で優れている。
【０１７０】
また、内包物であるコバルト又はコバルト合金の内包率がカーボンチューブ内空間部の１０〜９０％の範囲のものを製造できるので、特定の内包率を有する本発明コバルト又はコバルト合金内包炭素複合体を含む炭素質材料を選択することにより、電気的特性、磁気特性、比重等の諸物性を制御できる。
【０１７１】
比重に関しては、他物質との複合化の際、内包率１００％、即ちカーボンチューブの全長に亘ってコバルトなどの金属が内包されている複合体は、内包金属のために比重が高すぎて、他物質中への均一分散が困難となる場合もある。しかし、本発明のコバルト又はコバルト合金内包炭素複合体は内包率１０〜９０％の範囲で内包金属量を減少させることができるので、均一混合が容易となる。
【０１７２】
特に、本発明のナノフレークカーボンチューブとコバルト又はコバルト合金からなるコバルト又はコバルト合金内包炭素複合体は、次のような利点を有している。
(a) 電子放出の起点が多い。グラフェンシートのエッジからも電子放出が起こる可能性が大きいので、大きな電流密度を得る観点から有利である。
(b)黒鉛性が高いので寿命特性に優れる。
(c)ペーストとの馴染みが良くなる。黒鉛性が高いと、ペースト化の際、溶媒、ペースト剤との馴染みが悪くなるが、ナノフレークカーボンチューブとコバルト又はコバルト合金からなるコバルト又はコバルト合金内包炭素複合体はグラフェンシートのエッジの効果のためか、ペースト化が容易である。
(d)放熱性が良い。
(e)構造制御が容易である。側壁がフレーク状ないし張り子状であるため、切断加工、表面修飾などの構造制御が容易となる。
(f)フレキシブルである。側壁がフレーク状ないし張り子状であるために柔軟性が付与され、複合材料等に用いた場合には剛性と耐衝撃性を両立させることが出来る。
【図面の簡単な説明】
【図１】本発明の製造方法を行うための製造装置の一例を示す概略図である。
【図２】本発明の製造方法を行うための製造装置の他の例を示す概略図である。
【図３】カーボンチューブのTEM像の模式図を示し、(a-1)は、円柱状のナノフレークカーボンチューブのTEM像の模式図であり、(a-2)は入れ子構造の多層カーボンナノチューブのTEM像の模式図である。
【符号の説明】
１ 反応炉
２ 加熱装置
３ 加熱装置
１００ ナノフレークカーボンチューブの長手方向のTEM像
１１０ 略直線状のグラフェンシート像
２００ ナノフレークカーボンチューブの長手方向にほぼ垂直な断面のTEM像
２１０ 弧状グラフェンシート像
３００ 入れ子構造の多層カーボンナノチューブの長手方向の全長にわたって連続する直線状グラフェンシート像
４００ 入れ子構造の多層カーボンナノチューブの長手方向に垂直な断面のTEM像[0001]
BACKGROUND OF THE INVENTION
The present invention relates to cobalt or a cobalt alloy-containing carbon composite containing a cobalt-based compound such as cobalt or a cobalt alloy, a carbonaceous material containing the cobalt or cobalt alloy-containing carbon composite, and a method for producing the same.
[0002]
[Prior art]
A carbon nanotube is a hollow carbon material in which a graphite sheet (that is, a carbon atom plane or graphene sheet of a graphite structure) is closed like a tube, its diameter is nanometer scale, and the wall structure has a graphite structure. . Such a carbon nanotube was discovered in 1991 by Sumio Iijima. Among the carbon nanotubes, one with a single graphite sheet whose wall structure is closed in a tube shape is called a single-walled carbon nanotube, and a plurality of graphite sheets are each closed in a tube shape and are nested. It is called a multi-walled carbon nanotube with a nested structure.
[0003]
In addition, it has been reported that a graphite wall structure has a scroll shape, which is similar to an ordinary multi-walled carbon nanotube having a nested structure, but has a different wall structure made of carbon.
[0004]
In recent years, with the aim of improving electrical and magnetic properties of conductors, electron emitters, etc., a metal is encapsulated in a hollow portion surrounded by a tube wall such as these carbon nanotubes (hereinafter sometimes referred to as “CNTs”). Attempts have been made.
[0005]
For example, Japanese Patent No. 2546114 describes a foreign substance-encapsulated carbon nanotube in which a substance other than carbon such as metal is encapsulated in a hollow hole at the center of a nested multi-layer carbon nanotube. The foreign substance-encapsulated carbon nanotube is obtained by depositing a substance other than carbon on the tip of the carbon nanotube at the same time as or after removing the cap end of the nested multi-walled carbon nanotube that has been closed like a cap. It is manufactured by introducing into the hollow hole in the center of the tube from the tip of the tube.
[0006]
Japanese Laid-Open Patent Publication No. 9-142819 describes a carbon tube in which a foreign substance is included in a carbon tube having a diameter of 10 nm to 1 μm and a length of 1 to 100 μm. This foreign substance-encapsulating carbon tube uses an inorganic substance having substantially straight pores as a mold, and carbonizes an organic substance coated on the inner walls of the pores by heating, or gas in the pores. A carbon tube is temporarily produced by vapor-phase carbonization of a hydrocarbon in a gaseous state, and then a foreign substance is brought into contact with the tube in a solution state or a molten state to the hollow portion of the carbon tube. It is produced by inserting foreign substances (inorganic substances are dissolved and removed before or after insertion).
[0007]
Furthermore, Japanese Patent Laid-Open No. 2000-204471 discloses a fine metal wire made of a fine wire material having a diameter of 1 to 100 nm and a ratio of the diameter to the long axis length of 50 or more, particularly a fine metal wire covered with a carbon tube. Is described. The manufacturing method of the fine metal wire covered with the carbon tube is the same as the manufacturing method described in the above-mentioned Japanese Patent Application Laid-Open No. 9-142819, and a cylindrical shape is formed on the inner wall of an inorganic substance having substantially linear pores. It is manufactured by a manufacturing method comprising a first step of forming carbon and a second step of depositing metal inside the cylindrical carbon.
[0008]
[Problems to be solved by the invention]
However, the conventional method requires at least two steps of once forming a carbon tube and then inserting a foreign substance, which is complicated in terms of management and control of each step and has low productivity. Further, in the production methods described in JP-A Nos. 9-142819 and 2000-204471, a step of dissolving and removing the inorganic substance used as the mold is necessary.
[0009]
In addition, a method has been developed for obtaining a composite in which a metal such as cobalt is enclosed in a space surrounded by a wall made of carbon of a tubular carbon material such as a carbon nanotube in a carbon tube at a mg scale or more. Not. For this reason, no practical practical research has been conducted on a carbon-metal composite in which a metal such as cobalt is encapsulated in a hollow portion of a tubular carbon material.
[0010]
The main object of the present invention is to provide a composite in which a metal such as cobalt is enclosed in a substantial portion of the space surrounded by the carbon tube, a carbonaceous material containing such a composite, and a method for producing the same. Objective.
[0011]
[Means for Solving the Problems]
As a result of conducting research in view of the current state of the prior art as described above, the present inventors have found the following matters.
[0012]
(1) (1) Pressure is 10 in an inert gas atmosphere.^-FiveThe oxygen concentration in the reactor is adjusted to Pa to 200 kPa, and the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 1 × 10^-Ten~ 1x10^-1In a reaction furnace, the cobalt halide or (a) cobalt halide and (b) a halide such as other metals are heated to 600 to 1100 ° C. in a reaction furnace. ) The inside of the reactor is an inert gas atmosphere, and the pressure is 10^-FiveBy adjusting to Pa to 200 kPa, introducing a pyrolyzable carbon source and performing heat treatment at 600 to 1100 ° C., cobalt made of cobalt or cobalt alloy contained in the tube and a space inside the tube or A carbon material containing a cobalt alloy-encapsulating carbon composite can be produced all at once.
[0013]
(2) In the cooling step after the above step (2), the tube made of carbon obtained by controlling the cooling rate to a specific range has a plurality of flake-like graphite sheets (usually many) patchwork. This is a carbon tube made of an aggregate of graphite sheets, which is considered to be configured in the shape of a shape or a tensioner. In this specification, this carbon tube is referred to as a “nano flake carbon tube”. This nano flake carbon tube is a single-walled carbon nanotube in which a single graphite sheet is closed in a cylindrical shape or a multi-walled carbon nanotube in which a plurality of graphite sheets are closed in a cylindrical shape and are concentric cylindrical or nested. It is a tubular carbon material with a completely different structure.
[0014]
(3) The space in the tube of the nano flake carbon tube (that is, the space surrounded by the tube wall of the nano flake carbon tube) is a substantial part of the space, particularly 10 to 90% of the space is cobalt. Alternatively, it is filled with a cobalt alloy to form a cobalt or cobalt alloy-containing carbon composite.
[0015]
(4) Further, as a subsequent step of the above step (2), the tube made of carbon obtained by heat treatment in an inert gas and cooling at a specific cooling rate becomes a multi-walled carbon nanotube with a nested structure. Become. A space in the tube of the multi-walled carbon nanotube is filled with cobalt or a cobalt alloy in a substantial part of the space, particularly 10 to 90% of the space, thereby forming a cobalt or cobalt alloy-containing carbon composite. ing.
[0016]
The present invention has been completed through further studies based on these findings, and provides the following cobalt or cobalt alloy-containing carbon composite and a method for producing the same.
[0017]
Item 1 (a) A carbon tube selected from the group consisting of nano-flake carbon tubes and nested multi-walled carbon nanotubes, and (b) cobalt or cobalt alloy-containing carbon composites consisting of cobalt or a cobalt alloy, Cobalt or cobalt alloy-containing carbon composite, characterized in that 10 to 90% of the space is filled with cobalt or cobalt alloy.
[0018]
Item 2 It is linear, the outer diameter is 1 to 100 nm, the thickness of the wall portion made of carbon is 49 nm or less and substantially uniform over the entire length, the length is L, and the outer diameter is D Item 2. The cobalt or cobalt alloy inclusion carbon composite according to Item 1, wherein the aspect ratio L / D is 5 to 10,000.
[0019]
Item 3 The above item 1 wherein the average distance (d002) between the carbon network surfaces is 0.34 nm or less when the wall of the carbon tube constituting the cobalt or cobalt alloy-containing carbon composite is measured by X-ray diffraction. Or the cobalt or cobalt alloy inclusion carbon composite of 2.
[0020]
Item 4. The cobalt or cobalt alloy-encapsulated carbon composite according to any one of Items 1 to 3, wherein the carbon tube constituting the cobalt or cobalt alloy-encapsulated carbon composite is a nanoflake carbon tube.
[0021]
Item 5. The cobalt or cobalt alloy-encapsulated carbon composite according to any one of Items 1 to 3, wherein the carbon tube constituting the cobalt or cobalt alloy-encapsulated carbon composite is a multi-walled carbon nanotube having a nested structure.
[0022]
Item 6 The cobalt alloy contains 55% by weight or more of cobalt and is selected from the group consisting of carbon, Co, Fe, Cu, Mn, Cr, Pb, Zn, Mo, Al, Ti, Nb, Ta, S, and Si. Item 6. The cobalt or cobalt alloy-containing carbon composite according to any one of items 1 to 5, which is an alloy further containing at least one kind.
[0023]
Item 7 (a) A carbon tube selected from the group consisting of nano-flake carbon tubes and nested multi-walled carbon nanotubes and (b) cobalt or a cobalt alloy, and cobalt or cobalt in 10 to 90% of the space in the carbon tube A carbonaceous material containing cobalt or a cobalt alloy-containing carbon composite filled with an alloy.
[0024]
Item 8 25mm for 1mg of carbonaceous material²In the powder X-ray diffraction measurement of irradiating CuKα X-rays with the above irradiation area, the strongest integrated intensity among the peaks of 40 ° <2θ <50 ° attributed to cobalt or cobalt alloy contained in the carbon tube Where Ia is the integrated intensity of the peak indicating Ia, and Ib is the integrated intensity of the peak at 26 ° <2θ <27 ° attributed to the average distance (d002) between the carbon network surfaces of the carbon tube. Item 8. The carbonaceous material according to Item 7, wherein the ratio R is 0.3 to 4.4.
[0025]
Item 9 The cobalt or cobalt alloy-encapsulating carbon composite is linear, has an outer diameter of 1 to 100 nm, and has a wall thickness of 49 nm or less and is substantially uniform over the entire length. Item 9. The carbonaceous material according to Item 7 or 8, wherein the aspect ratio L / D is 5 to 10,000 when the length is L and the outer diameter is D.
[0026]
Item 10 The above item 7 wherein the average distance (d002) between the carbon network surfaces is 0.34 nm or less when the wall portion of the carbon tube constituting the cobalt or cobalt alloy-containing carbon composite is measured by an X-ray diffraction method. Carbonaceous material in any one of -9.
[0027]
Item 11. The carbonaceous material according to any one of Items 7 to 10, wherein the carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite is a nanoflake carbon tube.
[0028]
Item 12. The carbonaceous material according to any one of Items 7 to 10, wherein the carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite is a nested multi-walled carbon nanotube.
[0029]
Item 13 The cobalt alloy contains 55 wt% or more of cobalt, and is selected from the group consisting of carbon, Co, Fe, Cu, Mn, Cr, Pb, Zn, Mo, Al, Ti, Nb, Ta, S, and Si. Item 14. The cobalt or cobalt alloy-containing carbon composite according to any one of Items 7 to 13, which is an alloy further containing at least one kind.
[0030]
Item 14 (a) A carbon tube selected from the group consisting of a nano-flake carbon tube and a multi-layer carbon nanotube with a nested structure, and (b) cobalt or a cobalt alloy, and cobalt or cobalt in 10 to 90% of the space in the carbon tube A method for producing a carbonaceous material containing cobalt or a cobalt alloy-containing carbon composite filled with an alloy,
(1) Pressure is 10 in an inert gas atmosphere.^-FiveThe oxygen concentration in the reactor is adjusted to Pa to 200 kPa, and the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 1 × 10^-Ten~ 1x10^-1The cobalt halide is heated to 600 to 1100 ° C. in a reaction furnace, or (a) cobalt halide and (b) iron halide, nickel halide, copper halide, halogen At least one selected from the group consisting of manganese halide, chromium halide, lead halide, zinc halide, molybdenum halide, aluminum halide, titanium halide, niobium halide, tantalum halide, sulfur halide, and silicon halide Heating the seed to 600-1100 ° C., and
(2) The inside of the reactor is an inert gas atmosphere and the pressure is 10^-FiveThe manufacturing method characterized by including the process of adjusting to Pa-200kPa, introducing a heat-decomposable carbon source, and heat-processing at 600-1100 degreeC.
[0031]
Item 15 Cobalt or cobalt alloy filled in 10 to 90% of the nano-flake carbon tube and the space in the tube by cooling to 500 ° C. at 50 to 2000 ° C./h after the heat treatment step of step (2) Item 15. The method according to Item 14, wherein a carbonaceous material containing cobalt or a cobalt alloy-containing carbon composite is formed.
[0032]
Item 16 After the heat treatment step of step (2),
(3) A step of replacing the inside of the reactor with an inert gas while maintaining the temperature of step (2),
(4) A step of raising the temperature in the reactor substituted with an inert gas to 1100 to 1450 ° C.,
(5) a step of maintaining the end point temperature at the end point of temperature increase until a multi-walled carbon nanotube with a nested structure is formed, and
(6) The process of cooling the reactor at a rate of 50 ° C / h or less
To produce a carbonaceous material including a multi-walled carbon nanotube with a nested structure and cobalt or a cobalt alloy-containing carbon composite made of cobalt or a cobalt alloy filled in 10 to 90% of the space in the tube. 14. The production method according to 14.
[0033]
Item 17 The method according to Item 14, wherein the heat treatment in the step (2) is performed in the presence of an organic cobalt complex.
[0034]
Item 18. The method according to Item 17, wherein the organic cobalt complex is dicyclopentadienyl cobalt or a cobalt carbonyl complex.
[0035]
Item 19 The method according to any one of Items 14 to 18, wherein the cobalt halide is a chloride of cobalt.
[0036]
Item 20 Cobalt chloride is CoCl₂, CoCl₂・ H₂O, CoCl₂・ 1.5H₂O, CoCl₂・ 2H₂O, CoCl₂・ 4H₂O, CoCl₂・ 6H₂O and CoCl_ThreeItem 20. The production method according to Item 19, which is at least one selected from the group consisting of:
[0037]
Item 21 The pyrolyzable carbon source is selected from the group consisting of aromatic hydrocarbons having 6 to 12 carbon atoms, saturated aliphatic hydrocarbons having 1 to 10 carbon atoms, and unsaturated aliphatic hydrocarbons having 2 to 5 carbon atoms. Item 21. The method according to any one of Items 14 to 20, which is at least one.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Cobalt or cobalt alloy inclusion carbon composite of the present invention
The cobalt or cobalt alloy-encapsulating carbon composite according to the present invention comprises (a) a carbon tube selected from the group consisting of a nano-flake carbon tube and a multi-walled carbon nanotube with a nested structure, and (b) cobalt or a cobalt alloy. In addition, substantially all of the space inside the carbon tube (that is, the space surrounded by the tube wall) is not filled, but a part of the space, more specifically about 10 to 90%, especially About 30 to 80%, preferably about 40 to 70% is filled with cobalt or a cobalt alloy.
[0039]
In the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, the carbon part is subjected to the production steps (1) and (2), and then cooled at a specific rate to become a nanoflake carbon tube, and the production step (1) and After performing (2), heat treatment is performed in an inert gas, and cooling is performed at a specific cooling rate, so that a multi-walled carbon nanotube with a nested structure is obtained.
[0040]
<(A-1) Nano flake carbon tube>
The nano-flake carbon tube of the present invention and cobalt or a cobalt alloy-containing carbon composite made of cobalt or a cobalt alloy are typically cylindrical. FIG. 3 (a-1) shows a schematic diagram of a TEM image of such a columnar nano-flake carbon tube. In (a-1) of FIG. 3, 100 schematically shows a TEM image in the longitudinal direction of the nano flake carbon tube, and 200 indicates a TEM image in a cross section substantially perpendicular to the longitudinal direction of the nano flake carbon tube. This is shown schematically.
[0041]
As is apparent from 200 of FIG. 3 (a-1), the nanoflakes carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is observed by a TEM observation of a cross section across its longitudinal direction. A large number of arc-shaped graphene sheet images are gathered in a tube structure having a multilayer structure, but each graphene sheet image does not form a completely closed continuous ring, as shown in 210, 214, for example. It forms a discontinuous ring that is interrupted along the way. Some graphene sheet images may be branched as indicated by 211. At the discontinuity point, a plurality of arc-shaped TEM images constituting one discontinuous ring may have a partially disturbed layer structure as indicated by 222 in FIG. As shown by 223, there may be a space between adjacent graphene sheet images, but a large number of arc-shaped graphene sheet images observed by TEM form a multilayer tube structure as a whole. Yes.
[0042]
Further, as is clear from 100 in FIG. 3 (a-1), when the longitudinal direction of the nano flake carbon tube is observed by TEM, a number of substantially straight graphene sheet images are included in the cobalt or cobalt alloy inclusion of the present invention. The graphene sheet images 110 are not continuous over the entire length in the longitudinal direction of the cobalt or cobalt alloy-containing carbon composite, but are discontinuous in the middle. It has become. Some graphene sheet images may be branched as indicated by reference numeral 111 in FIG. Further, at the discontinuous point, among the TEM images arranged in a layered manner, one TEM image of the discontinuous layer is at least partly adjacent to the adjacent graphene sheet image as indicated by 112 in FIG. In some cases, they may overlap each other, or as shown at 113, they may be slightly apart from the adjacent graphene sheet images, but a large number of substantially linear TEM images form a multilayer structure as a whole.
[0043]
The structure of the nanoflake carbon tube of the present invention is greatly different from the conventional multi-walled carbon nanotube. That is, as shown by 400 in FIG. 3 (a-2), the multi-walled carbon nanotube having a nested structure has a TEM image of a cross section perpendicular to the longitudinal direction thereof, as shown by 410, and a completely circular TEM image. A concentric tube, and a structure in which straight graphene sheet images 310 and the like continuous over the entire length in the longitudinal direction are arranged in parallel as indicated by 300 in FIG. (Concentric cylindrical or nested structure).
[0044]
Although the details have not been fully elucidated from the above, the nano-flake carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention has a large number of flake-like graphene sheets overlapping in a patchwork or tension form. It seems to form a tube as a whole.
[0045]
Such a nano-flake carbon tube of the present invention and a cobalt or cobalt alloy-encapsulated carbon composite made of cobalt or a cobalt alloy encapsulated in the space inside the tube have a nested structure as described in Japanese Patent No. 2546114. Compared to the composite in which the metal is included in the space in the tube of the multi-walled carbon nanotube, the structure of the carbon tube is greatly different, and it is a novel carbon material that has not been known so far.
[0046]
In the case of TEM observation of the nano flake carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, each graphene sheet relates to a number of substantially linear graphene sheet images oriented in the longitudinal direction. The length of the image is usually about 2 to 500 nm, particularly about 10 to 100 nm. That is, as indicated by 100 in FIG. 3 (a-1), a large number of TEM images of the substantially linear graphene sheet indicated by 110 are collected to form a TEM image of the wall portion of the nanoflake carbon tube. The length of each substantially linear graphene sheet image is usually about 2 to 500 nm, particularly about 10 to 100 nm.
[0047]
The carbon portion of the wall portion of the nano flake carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention has a tube shape as a whole with a plurality of flake-like graphene sheets oriented in the longitudinal direction as described above. However, when measured by the X-ray diffraction method, the carbon fiber has an average distance (d002) between the carbon network surfaces of 0.34 nm or less.
[0048]
Moreover, the thickness of the wall part which consists of the nano flake carbon tube of the cobalt or cobalt alloy inclusion | inner_cover carbon composite of this invention is 49 nm or less, Especially about 0.1-20 nm, Preferably it is about 1-10 nm, Comprising: It is substantially uniform throughout.
[0049]
<(A-2) Nested multi-walled carbon nanotubes>
As described above, by performing the specific heating step after performing the steps (1) and (2), the carbon tube constituting the obtained cobalt or cobalt alloy-encapsulating carbon composite is a multi-layer carbon nanotube having a nested structure. It becomes.
[0050]
The nested multi-walled carbon nanotube thus obtained is a concentric tube in which a TEM image of a cross section perpendicular to the longitudinal direction forms a complete circle, as indicated by reference numeral 400 in FIG. And it is the structure (concentric cylindrical shape or nested structure) where the graphene sheet images continuous over the entire length in the longitudinal direction are arranged in parallel.
[0051]
The carbon portion of the wall portion of the nested multi-walled carbon nanotube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention has an average distance (d002) between carbon network surfaces of 0 when measured by X-ray diffraction. It has a graphite structure of .34 nm or less.
[0052]
Further, the thickness of the wall portion composed of the multi-walled carbon nanotube of the nested structure of the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is 49 nm or less, particularly about 0.1 to 20 nm, preferably about 1 to 10 nm, It is substantially uniform over the entire length.
[0053]
<(B) Cobalt or cobalt alloy contained>
In this specification, the filling rate (10 to 90%) of cobalt or a cobalt alloy in the space part in the carbon tube is observed with a transmission electron microscope for the cobalt or cobalt alloy-containing carbon composite obtained by the present invention. This is the ratio of the area of the image of the portion filled with cobalt or cobalt alloy to the area of the image of the space of each carbon tube (that is, the space surrounded by the tube wall of the carbon tube).
[0054]
The filling form of cobalt or cobalt alloy includes a form in which the space in the carbon tube is continuously filled and a form in which the space in the carbon tube is filled intermittently. Filled. Therefore, the cobalt or cobalt alloy-encapsulating carbon composite of the present invention should also be referred to as a metal-encapsulated carbon composite, a cobalt compound-encapsulating carbon composite, or a cobalt or cobalt alloy-encapsulating carbon composite.
[0055]
In the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, examples of the cobalt alloy encapsulated in the carbon tube include various cobalt-based alloys. For example, cobalt is 55% by weight or more (preferably 55 to 95% by weight). %), Especially 65% by weight or more (preferably 65 to 95% by weight), with the balance being carbon, Ni, Fe, Cu, Mn, Cr, Pb, Zn, Mo, Al, Ti, Nb, Ta, S and An alloy that is at least one selected from the group consisting of Si is preferable.
[0056]
Among these cobalt alloys, in particular, iron-cobalt, iron-cobalt-nickel containing 55 wt% or more (preferably 55 to 95 wt%), particularly 65 wt% or more (preferably 65 to 95 wt%) of cobalt, Cobalt-nickel, copper-cobalt, cobalt-chromium and the like, and these carbon-containing alloys are preferred.
[0057]
Carbon, sulfur and silicon are not metals, but in this specification, the term “alloy” means that at least one selected from the group consisting of carbon, sulfur and silicon is cobalt or other than cobalt and cobalt. The materials contained in alloys with these metals (Ni, Fe, Cu, Mn, Cr, Pb, Zn, Mo, Al, Ti, Nb, Ta) are also included.
[0058]
The cobalt or cobalt alloy included in the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is oriented in the longitudinal direction of the carbon tube, has high crystallinity, and is filled with cobalt or a cobalt alloy. The ratio of the area of the TEM image of crystalline cobalt or cobalt alloy to the area of the TEM image (hereinafter referred to as “crystallization rate”) is generally about 90 to 100%, particularly about 95 to 100%.
[0059]
The high crystallinity of the included cobalt or cobalt alloy is because the TEM images of the inclusions are arranged in a lattice pattern when TEM observation is performed from the side surface of the cobalt or cobalt alloy-containing carbon composite of the present invention. It is clear, and it is also clear from the fact that a clear diffraction pattern can be obtained from electron diffraction.
[0060]
Moreover, it can be easily confirmed with an electron microscope and EDX (energy dispersive X-ray detector) that cobalt or a cobalt alloy is included in the cobalt or cobalt alloy-containing carbon composite of the present invention.
[0061]
<Overall shape of cobalt or cobalt alloy inclusion carbon composite>
The cobalt or cobalt alloy-encapsulating carbon composite of the present invention is less curved, straight, and has a uniform thickness over the entire length of the wall, so it is homogeneous over the entire length. It has a different shape. The shape is columnar and mainly cylindrical.
[0062]
The outer diameter of the cobalt or cobalt alloy-containing carbon composite according to the present invention is usually about 1 to 100 nm, particularly about 1 to 50 nm, preferably about 1 to 30 nm, more preferably 10 to 30 nm. It is in the range of the degree. The aspect ratio (L / D) of the tube length (L) to the outer diameter (D) is about 5 to 10,000, and particularly about 10 to 1,000.
[0063]
The term “linear”, which is one term representing the shape of the cobalt or cobalt alloy-containing carbon composite of the present invention, is defined as follows. That is, the carbonaceous material containing the cobalt or cobalt alloy-containing carbon composite of the present invention was observed in a range of 200 to 2000 nm square by a transmission electron microscope, the length of the image was set to W, and the image was straightened. When the length of time is Wo, it means a shape characteristic in which the ratio W / Wo is 0.8 or more, particularly 0.9 or more.
[0064]
Carbonaceous material containing cobalt or cobalt alloy inclusion carbon composite
The cobalt or cobalt alloy-containing carbon composite of the present invention has the following properties when viewed as a bulk material. That is, in the present invention, cobalt or a cobalt alloy is filled in the range of 10 to 90% of the space in the tube of the carbon tube selected from the nano flake carbon tube and the multi-walled carbon nanotube of the nested structure as described above. Cobalt alloy inclusion carbon composite is not a trace amount that can be barely observed by microscopic observation, but is a bulk material containing a large number of the cobalt or cobalt alloy inclusion carbon composite, It is obtained in a large amount in the form of a material that should be referred to as a carbonaceous material containing cobalt or a cobalt alloy.
[0065]
In the carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, basically, in almost all (particularly 99% or more) carbon tubes, the space (that is, the tube wall of the carbon tube). In general, a carbon tube in which 10 to 90% of the space) is filled with cobalt or a cobalt alloy and the space portion is not filled is substantially absent. However, in some cases, a small amount of carbon tubes not filled with cobalt or a cobalt alloy may be mixed.
[0066]
Moreover, in the carbonaceous material of the present invention, cobalt or a cobalt alloy-encapsulating carbon composite in which 10 to 90% of the above-described carbon tube inner space is filled with cobalt or a cobalt alloy is a main constituent. In addition to the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, soot may be contained. In such a case, components other than the cobalt or cobalt alloy inclusion carbon composite of the present invention are removed to improve the purity of the cobalt or cobalt alloy inclusion carbon composite in the carbonaceous material of the present invention. It is also possible to obtain a carbonaceous material consisting only of the cobalt or cobalt alloy-containing carbon composite of the invention.
[0067]
Also, unlike materials that could only be confirmed in microscopic amounts by conventional microscopic observation, the carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention can be synthesized in large quantities, and its weight can easily be 1 mg or more. It can be. There is virtually no upper limit because the material of the present invention can be produced indefinitely by scaling up or repeating the process of the present invention described below. In general, the carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention may be in an amount of about 1 mg to 100 g, particularly about 10 to 1000 mg, even at a laboratory level with a reactor volume of about 1 liter. Can be easily provided.
[0068]
Inventive carbonaceous material is 25 mm per 1 mg of the carbonaceous material.²In the powder X-ray diffraction measurement in which the X-ray of CuKα is irradiated with the above irradiation area, it shows the strongest integrated intensity among the peaks of 40 ° <2θ <50 ° attributed to the included cobalt or cobalt alloy. When the integrated intensity of the peak is Ia, and the integrated intensity Ib of the peak of 26 ° <2θ <27 ° attributed to the average distance (d002) between the carbon network surfaces of the carbon tube, the ratio R ( = Ia / Ib) is preferably about 0.3 to 4.4, particularly about 0.4 to 3.5, and more preferably about 1.1 to 3.2.
[0069]
In this specification, the ratio of Ia / Ib is referred to as an R value. This R value is 25 mm in the X-ray diffraction method of the carbonaceous material containing the cobalt or cobalt alloy-containing carbon composite of the present invention.²Since the peak intensity is observed as the average value of the entire carbonaceous material when observed with the above X-ray irradiation area, the inclusion rate or filling in one cobalt or cobalt alloy inclusion carbon composite that can be measured by TEM analysis It shows not the rate but the average value of the cobalt or cobalt alloy filling rate or inclusion rate as the whole carbonaceous material which is an aggregate of cobalt or cobalt alloy inclusion carbon composite.
[0070]
The average filling rate of the entire carbonaceous material including a large number of cobalt or cobalt alloy-encapsulating carbon composites of the present invention is obtained by observing a plurality of fields of view with TEM, and a plurality of cobalt or cobalt alloy-encapsulated carbons observed in each field of view. It can also be determined by measuring the average filling factor of cobalt or cobalt alloy in the composite and calculating the average value of the average filling factors of a plurality of visual fields. When measured by such a method, the average filling rate of cobalt or cobalt alloy as a whole carbonaceous material comprising the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is about 10 to 90%, particularly about 40 to 70%. .
[0071]
Cobalt or cobalt alloy-containing carbon composite of the present invention and method for producing carbonaceous material containing the same (first production method)
The carbonaceous material containing the cobalt or cobalt alloy-containing carbon composite of the present invention,
(1) Pressure is 10 in an inert gas atmosphere.^-FiveThe oxygen concentration in the reactor is adjusted to Pa to 200 kPa, and the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 1 × 10^-Ten~ 1x10^-1The cobalt halide is heated to 600 to 1100 ° C. in the reaction furnace, or (a) cobalt halide and (b) iron halide, nickel halide, copper halide, halogen At least one selected from the group consisting of manganese halide, chromium halide, lead halide, zinc halide, molybdenum halide, aluminum halide, titanium halide, niobium halide, tantalum halide, sulfur halide, and silicon halide Heating the seed to 600-1100 ° C., and
(2) The inside of the reactor is an inert gas atmosphere and the pressure is 10^-FiveIt adjusts to Pa-200kPa, is obtained by the manufacturing method including the process of introduce | transducing a heat-decomposable carbon source and heat-processing at 600-1100 degreeC.
[0072]
Here, “Ncc”, which is a unit of the oxygen amount B, means a volume (cc) when converted to a standard state of gas at 25 ° C.
[0073]
Examples of the cobalt halide which is a supply source of cobalt or a cobalt alloy contained therein and also exhibits a function as a catalyst include cobalt fluoride, cobalt chloride, cobalt bromide and the like. Among these, cobalt chloride Is preferred. Examples of cobalt chloride include CoCl₂, CoCl₂・ H₂O, CoCl₂・ 1.5H₂O, CoCl₂・ 2H₂O, CoCl₂・ 4H₂O, CoCl₂・ 6H₂O, CoCl_ThreeEtc., and at least one of these is used. The shape of these catalysts is not particularly limited, but usually, it is preferably used in a powder form, for example, a powder form having an average particle diameter of about 1 to 100 μm, particularly about 1 to 20 μm, or in a gaseous form.
[0074]
In addition, when obtaining a composite in which the inclusion is a cobalt alloy, the iron halide, nickel halide, copper halide, manganese halide, chromium halide, halogenated together with the cobalt halide in the reaction furnace. At least one selected from the group consisting of lead, zinc halide, molybdenum halide, aluminum halide, titanium halide, niobium halide, tantalum halide, sulfur halide, and silicon halide (hereinafter referred to as at least one species). “Cocatalyst”) may be present.
[0075]
Also in this case, the cobalt halide and the cocatalyst are preferably used in the form of powder having an average particle diameter of about 1 to 100 μm, particularly about 1 to 20 μm. The usage ratio of both may be selected as appropriate from a wide range, but generally the ratio is such that cobalt is the main component. For example, the cobalt halide is used in an amount of about 55 to 95% by weight, particularly about 65 to 95% by weight of the total amount of the cobalt halide and the cocatalyst.
[0076]
Cobalt halide and cocatalyst can be present in the reactor as follows: a) a method in which both are placed in different parts of the reactor, b) both are dry-mixed in advance, and the resulting mixture is placed in the reactor. C) a powder obtained by uniformly dissolving or dispersing both in an organic solvent (for example, a lower alcohol such as methanol) and then pulverizing the residue obtained by distilling off the organic solvent. The method etc. which are made to exist in a reaction furnace can be illustrated.
[0077]
As the pyrolytic carbon source, various organic compounds can be used, for example, aromatic hydrocarbons having 6 to 12 carbon atoms such as benzene, toluene, xylene, etc., carbon atoms of 1 such as methane, ethane, propane, butane, hexane and the like. Organic compounds such as 10 to 10 saturated aliphatic hydrocarbons and unsaturated aliphatic hydrocarbons having 2 to 5 carbon atoms such as ethylene, propylene, and acetylene. The liquid organic compound is usually used after being vaporized. Among these, benzene, toluene and the like are preferable.
[0078]
As a reaction apparatus used by this invention, an apparatus as shown in FIG. 1 can be illustrated, for example. In the apparatus of FIG. 1, the reaction furnace 1 is a reaction furnace composed of a quartz tube, an alumina tube, a carbon tube, and the like, and includes a heating device 2. The reaction furnace is provided with a gas inlet (not shown) and a gas inlet (not shown) for vacuuming. The cobalt halide is placed in the reaction furnace, for example, by thinly spreading and spreading on a cobalt halide preparation tray 10 such as a porcelain boat or a cobalt boat.
[0079]
Process (1)
In the production method of the present invention, first, in the reaction furnace, the above-mentioned catalyst and raw material cobalt halide or (a) cobalt halide and (b) cocatalyst (that is, iron halide, cobalt halide) , Copper halide, manganese halide, chromium halide, lead halide, zinc halide, molybdenum halide, aluminum halide, titanium halide, niobium halide, tantalum halide, sulfur halide and silicon halide At least one selected from the group) in an inert gas atmosphere up to 600 to 1100 ° C., particularly about 800 to 1100 ° C.
[0080]
Inert gases include He, Ar, Ne, N₂Etc. can be illustrated. The pressure in the reactor when the catalyst is heat-treated in an inert gas atmosphere is, for example, 10^-FiveIt is preferably about Pa to 200 kPa, particularly about 0.1 kPa to 100 kPa.
[0081]
The heat treatment is performed until the temperature in the reaction furnace, particularly the temperature of the catalyst, reaches the thermal decomposition temperature of the pyrolytic carbon source used in the step (2). The pyrolysis temperature of the pyrolyzable carbon source varies depending on the type of the pyrolyzable carbon source, but in general, the temperature of the catalyst in the reaction furnace is about 600 to 1100 ° C, particularly about 800 to 1100 ° C. preferable.
[0082]
According to the study of the present inventor, it is preferable that a small amount of oxygen is present during the heating in step (1). When a large amount of oxygen is present, the cobalt halide or cocatalyst becomes an oxide such as cobalt oxide, and it is difficult to obtain a desired complex. Accordingly, the oxygen concentration in the reactor is 1 × 10, where the ratio B / A is 1 × 10 when the reactor volume is A (liter) and the oxygen amount is B (Ncc).^-Ten~ 1x10^-1, Especially 1 × 10^-8~ 5x10^-3It is preferable that the concentration be such that
[0083]
In this case, various methods can be adopted as the method for introducing oxygen. For example, a mixed gas composed of an inert gas such as argon containing about 5 to 0.01% of oxygen is introduced from the gas inlet of the reactor. It is preferable to add gradually.
[0084]
Process (2)
Next, in the present invention, as step (2), a reaction comprising cobalt halide heated to 600 to 1100 ° C. by heat treatment in step (1) or (a) cobalt halide and (b) a cocatalyst. The inside of the furnace is set to an inert gas atmosphere, and a heat decomposable carbon source is introduced from the gas inlet to perform heat treatment.
[0085]
The pressure at the time of heat treatment in this step (2) is 10^-FiveIt is preferably about Pa to 200 kPa, particularly about 1 kPa to 100 kPa. The temperature during the heat treatment in step (2) is usually 600 ° C. or higher, particularly 600 to 1100 ° C., preferably about 750 to 1100 ° C.
[0086]
As a method for introducing a pyrolytic carbon source, for example, an inert gas carrying a pyrolytic carbon source such as benzene by bubbling an inert gas such as argon gas to the pyrolytic carbon source such as benzene. However, the method is not limited to this method, and other methods may be adopted. The supply rate of the inert gas carrying the pyrolyzable carbon source such as benzene can be selected from a wide range, but is generally about 0.1 to 1000 ml / min, particularly 1 to 1 per liter of the reactor volume. The speed is preferably about 100 ml / min. At that time, if necessary, an inert gas such as Ar, Ne, He, or nitrogen may be introduced as a dilution gas.
[0087]
The quantitative ratio of cobalt halide, or (a) cobalt halide, (b) cocatalyst, and pyrolyzable carbon source may be appropriately selected from a wide range, but 100 parts by weight of cobalt halide, or ( It is preferable that the pyrolyzable carbon source is about 10 to 5000 parts by weight, particularly about 50 to 300 parts by weight, based on 100 parts by weight of the total of a) cobalt halide and (b) cocatalyst. When the quantitative ratio of the organic compound that is the pyrolyzable carbon source increases, the carbon tube is sufficiently grown to obtain a long-sized carbon tube.
[0088]
The reaction time in the step (2) varies depending on the type and amount of the raw material and is not particularly limited, but is usually about 0.1 to 10 hours, particularly about 0.5 to 2 hours.
[0089]
By cooling to 500 ° C. at a rate of usually about 50 to 2000 ° C./h, preferably about 70 to 1500 ° C./h, more preferably about 100 to 1000 ° C./h after the heat treatment step of the above step (2). A cobalt or cobalt alloy-encapsulating carbon composite made of cobalt or a cobalt alloy filled in a nano-flake carbon tube and 10 to 90% of the space in the tube can be produced.
[0090]
In addition, after the heat treatment step of step (2),
(3) A step of replacing the inside of the reactor with an inert gas while maintaining the temperature of step (2),
(4) A step of raising the temperature of the reaction furnace substituted with an inert gas to about 1100 to 1450 ° C, preferably about 1200 to 1450 ° C, more preferably about 1300 to 1400 ° C,
(5) a step of maintaining the end point temperature at the end point of temperature increase until a multi-walled carbon nanotube with a nested structure is formed, and
(6) A step of cooling the reactor at a rate of about 50 ° C./h or less, preferably about 5 to 40 ° C./h, more preferably about 10 to 30 ° C./h.
By performing the above, it is possible to generate a cobalt or cobalt alloy-encapsulating carbon composite composed of cobalt or a cobalt alloy filled in 10 to 90% of the multi-walled carbon nanotube with a nested structure and the space portion in the tube.
[0091]
Examples of the inert gas used in the above step (3) include inert gases such as Ar, Ne, He, and nitrogen. Further, the pressure in the furnace after replacement in step (3) is not particularly limited, but 10^-Five~Ten⁷Pa degree, preferably 50-2 × 10^FiveAbout Pa, more preferably 100-1.2 × 10^FiveIt is about Pa.
[0092]
The temperature raising rate in step (4) is not particularly limited, but is generally about 50 to 2000 ° C./h, particularly about 70 to 1500 ° C./h, more preferably about 100 to 1000 ° C./h. Is preferred.
[0093]
In addition, the time for maintaining the end point temperature in the step (5) may be a time until the nested multi-walled carbon nanotube is generated, but is generally about 2 to 30 hours.
[0094]
The atmosphere at the time of cooling in step (6) is an inert gas atmosphere such as Ar, Ne, He, nitrogen, etc., and the pressure conditions are not particularly limited.^-Five~Ten⁷Pa degree, preferably 50-2 × 10^FiveAbout Pa, more preferably 100-1.2 × 10^FiveIt is about Pa.
[0095]
Yield improvement method (second manufacturing method)
Further, according to another embodiment of the present invention, by supplying an organic cobalt complex together with a pyrolyzable carbon source in step (2) of the first production method, the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is further provided. Yield can be increased. In the present specification, the manufacturing method of this embodiment is referred to as a “second manufacturing method”.
[0096]
Examples of the organic cobalt complex include dicyclopentadienyl cobalt and Co.₂(CO)₈, Co_Four(CO)₁₂Among them, dicyclopentadienyl cobalt is particularly preferable.
[0097]
The method for allowing an organic cobalt complex such as dicyclopentadienyl cobalt to be present in the reaction system can be carried out by various methods. As a typical method, for example, the method shown in FIG. 2 can be adopted.
[0098]
That is, first, as shown in FIG. 2, in a reactor equipped with a gas inlet (not shown) and a gas suction port (not shown), an organic substance is formed upstream (ie, at a position close to the gas inlet). A preparation tray 20 such as a magnetic boat containing a cobalt complex is arranged, and a preparation tray 10 such as a magnetic boat containing cobalt halide is arranged downstream (position far from the gas inlet). When using a cobalt halide and a cocatalyst, the cobalt halide and the cocatalyst may be placed in separate feeding dishes and arranged in the reaction system.
[0099]
Next, as the step (1), cobalt halide or cobalt halide and a cocatalyst are set to a pressure of 10 in an inert gas atmosphere.^-FiveThe oxygen concentration in the reactor is adjusted to Pa to 200 kPa, and the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 1 × 10^-Ten~ 1x10^-1, Especially 1 × 10^-8~ 5x10^-3It adjusts to the density | concentration which becomes and heats with the heating apparatus 2 to 600-1100 degreeC, especially to 800-1100 degreeC.
[0100]
Subsequently, in step (2), the inside of the reactor is set to an inert gas atmosphere, and the pressure is set to 10.^-FiveIt is controlled to Pa to 200 kPa, preferably 1 Pa to 100 kPa. On the other hand, the organic cobalt complex is heated to a sublimation temperature of the organic cobalt complex or higher (200 ° C. in the case of dicyclopentadienyl cobalt) by another heating device 3 to form an organic compound such as dicyclopentadienyl cobalt. While the cobalt complex is in a gas phase, a mixed gas of a pyrolytic carbon source and an inert gas is introduced into the reaction furnace. At that time, if necessary, an inert gas such as Ar, Ne, He, or nitrogen may be introduced as a dilution gas. This system is heat treated. The conditions for this heat treatment are basically the same as those described for “Step (2)” of the first production method.
[0101]
That is, the pressure at the time of performing the heat treatment is 10^-FiveIt is preferably about Pa to 200 kPa, particularly about 1 kPa to 100 kPa. Moreover, the temperature at the time of the said heat processing is 600 degreeC or more normally, Especially 600-1100 degreeC, Preferably it is about 750-1100 degreeC. The supply rate of the inert gas carrying the pyrolyzable carbon source such as benzene can be selected from a wide range, but is generally about 0.1 to 1000 ml / min, particularly 1 to 1 per liter of the reactor volume. The speed is preferably about 100 ml / min. The time for the heat treatment varies depending on the type and amount of the raw material and is not particularly limited, but is usually about 0.1 to 10 hours, particularly about 0.5 to 2 hours.
[0102]
In the above, the quantitative proportions of the organic cobalt complex, the cobalt halide (or the cobalt halide and cocatalyst), and the thermally decomposable carbon source can be selected from a wide range, but in general, the following is preferable. The organic cobalt complex is used in an amount of about 1 to 5000 parts by weight, preferably about 10 to 1000 parts by weight, per 100 parts by weight of cobalt halide (or cobalt halide and cocatalyst). The amount of the pyrolyzable carbon source used is preferably about 10 to 5000 parts by weight, particularly about 50 to 300 parts by weight, per 100 parts by weight of cobalt halide (or cobalt halide and cocatalyst).
[0103]
According to this second production method, the yield of the carbonaceous material containing the obtained cobalt or cobalt alloy-containing carbon composite is improved.
[0104]
As in the case of the first production method, after the heat treatment step of the above step (2), it is usually about 50 to 2000 ° C./h, preferably about 70 to 1500 ° C./h, more preferably about 100 to 1000 ° C./h. By cooling to 500 ° C. at a rate of 5 ° C., a cobalt or cobalt alloy-encapsulating carbon composite made of cobalt or a cobalt alloy filled in 10 to 90% of the space portion in the tube can be generated. .
[0105]
In addition, after the heat treatment step of step (2),
(3) A step of replacing the inside of the reactor with an inert gas while maintaining the temperature of step (2),
(4) A step of raising the temperature of the reaction furnace substituted with an inert gas to about 1100 to 1450 ° C, preferably about 1200 to 1450 ° C, more preferably about 1300 to 1400 ° C,
(5) a step of maintaining the end point temperature at the end point of temperature increase until a multi-walled carbon nanotube with a nested structure is formed, and
(6) A step of cooling the reactor at a rate of 50 ° C./h or less, preferably about 5 to 40 ° C./h, more preferably about 10 to 30 ° C./h.
By performing the above, it is possible to generate a cobalt or cobalt alloy-encapsulating carbon composite composed of cobalt or a cobalt alloy filled in 10 to 90% of the multi-walled carbon nanotube with a nested structure and the space portion in the tube.
[0106]
Examples of the inert gas used in the above step (3) include inert gases such as Ar, Ne, He, and nitrogen. Further, the pressure in the furnace after replacement in step (3) is not particularly limited, but 10^-Five~Ten⁷Pa degree, preferably 50-2 × 10^FiveAbout Pa, more preferably 100-1.2 × 10^FiveIt is about Pa.
[0107]
The temperature raising rate in step (4) is not particularly limited, but is generally about 50 to 2000 ° C./h, particularly about 70 to 1500 ° C./h, more preferably about 100 to 1000 ° C./h. Is preferred.
[0108]
In addition, the time for maintaining the end point temperature in the step (5) may be a time until the nested multi-walled carbon nanotube is generated, but is generally about 2 to 30 hours.
[0109]
The atmosphere at the time of cooling in step (6) is an inert gas atmosphere such as Ar, Ne, He, nitrogen, etc., and the pressure conditions are not particularly limited.^-Five~Ten⁷Pa degree, preferably 50-2 × 10^FiveAbout Pa, more preferably 100-1.2 × 10^FiveIt is about Pa.
[0110]
From the carbonaceous material obtained by said 1st manufacturing method or the 2nd manufacturing method, the cobalt or cobalt alloy inclusion carbon composite which comprises this material can also be isolated.
[0111]
The cobalt or cobalt alloy-containing carbon composite obtained by the first production method or the second production method of the present invention has the following unique properties.
[0112]
A carbon tube selected from the group consisting of a nano flake carbon tube constituting a wall portion and a multi-walled carbon nanotube having a nested structure has higher linearity than known CNTs. Since the linearity is high, the bulk density can be increased, and many carbon tubes can be packed in a certain volume, so that packing can be performed at a high density. Also, for electron emission applications, high linearity is an advantage.
[0113]
10 to 90% of the space surrounded by the tube wall is filled with cobalt or a cobalt alloy. Cobalt or cobalt alloy present in the space exists in a highly developed crystalline state, as is apparent from the examples. Therefore, since the inclusion body exhibits magnetism and the surface layer is covered with carbon, a novel molecular magnet excellent in durability can be obtained.
[0114]
It is known that the electrical or magnetic properties of carbon nanotubes that do not encapsulate metals are highly dependent on the structure of the wall, but in order to bring out specific electrical or magnetic properties uniformly, the wall structure must be refined. Need to control. For example, in the case of hollow single-walled carbon nanotubes that do not contain inclusions, it is theoretically known that the graphene sheet is wound in an armchair type, zigzag type, or chiral type, which has different conductive properties and becomes a conductor or semiconductor. It has been. However, precise control of the wall structure is extremely difficult with current synthesis techniques.
[0115]
On the other hand, the carbon material of the present invention in which 10 to 90% of cobalt or a cobalt alloy is included in the hollow portion of the carbon tube selected from the group consisting of the nano-flake carbon tube of the present invention and the multi-layered carbon nanotube of the nested structure, Since the electrical or magnetic characteristics are mainly caused by the inclusion metal rather than the wall structure made of carbon, it is superior in that it does not require precise control of the wall structure, and is easy to manufacture. In particular, in the case of a nano flake carbon tube, since the wall structure is isotropic while maintaining the graphitic property, the ratio of electrical characteristics depending on the inclusion metal increases, and the control of the characteristics becomes easy.
[0116]
The cobalt or cobalt alloy-encapsulating carbon composite of the present invention having high linearity and containing cobalt or a cobalt alloy is excellent in electron emission ability, has high magnetic orientation, and is suitable for FED (field emission display) applications. Can be.
[0117]
In addition, even when the cobalt or cobalt alloy-encapsulated carbon composite of the present invention is blended and used as a conductive additive in a resin or the like, an improvement in conductivity is recognized with a small blending amount. The transparency, hue, etc. are not impaired.
[0118]
Moreover, there exists an advantage that the intensity | strength of a resin molding increases by mix | blending the cobalt or cobalt alloy inclusion carbon composite of this invention with resin.
[0119]
Furthermore, the cobalt or cobalt alloy-encapsulating carbon composite of the present invention can gradually release the encapsulated metal or the like when a part of the wall is opened by chemical treatment.
[0120]
【Example】
Examples are given below to describe the features of the present invention in more detail.
[0121]
Example 1
The reaction apparatus as shown in FIG. 1 was used to obtain the cobalt or cobalt alloy-containing carbon composite of the present invention as follows.
[0122]
Process (1)
Anhydrous CoCl₂Spread 0.2 g (Kanto Chemical Co., Ltd.) thinly in a nickel boat. This is installed in the center of the furnace made of quartz tube, and the inside of the furnace is depressurized to a pressure of 50 Pa. At this time, argon gas containing 5000 ppm of oxygen is supplied at a rate of 50 ml / min from the side opposite to the end of the reactor equipped with a vacuum suction line (left side of the reaction tube in FIG. 1). Accordingly, the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 6 × 10 6.^-3It was. Next, the temperature is raised to 1000 ° C. with reduced pressure.
[0123]
Process (2)
When the temperature reached 1000 ° C., argon was introduced and the pressure was 6.7 × 10 6.^FourControl to Pa. On the other hand, as a pyrolytic carbon source, argon gas was bubbled into a benzene tank, and a mixed gas of volatilized benzene and argon was introduced into the furnace at a flow rate of 60 ml / min per 1 liter of reactor volume, and diluted gas As described above, argon gas is introduced at a flow rate of 40 ml / min.
[0124]
A carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention by reacting at a reaction temperature of 1000 ° C. for 90 minutes, lowering the temperature to 500 ° C. in 20 minutes, and then removing the heater and air-cooling to room temperature in 20 minutes. Of 300 mg was obtained.
[0125]
From the results of SEM observation, the obtained cobalt or cobalt alloy-containing carbon composite was highly linear with an outer diameter of 20 to 50 nm and a length of 3 to 5 microns. Moreover, the thickness of the wall part which consists of carbon was 2-10 nm, and was substantially uniform over the full length. Further, it was confirmed from the TEM observation and the X-ray diffraction method that the wall portion was a nanoflake carbon tube having a graphite structure having an average distance (d002) between carbon network surfaces of 0.34 nm or less. Moreover, it was confirmed by X-ray diffraction and EDX that cobalt carbide was included in the cobalt or cobalt alloy-containing carbon composite of the present invention.
[0126]
When a large number of cobalt or cobalt alloy-encapsulated carbon composites (cobalt carbide-encapsulated carbon composites) constituting the obtained carbonaceous material of the present invention were observed with an electron microscope (TEM), the space portion of the nanoflake carbon tube (that is, Cobalt or cobalt alloy-containing carbon composites having various filling rates in the range of 10 to 80% of the filling rate of cobalt carbide into the space surrounded by the tube wall of the nano flake carbon tube were mixed.
[0127]
Incidentally, the average filling rate of cobalt carbide in the space portion of the nano flake carbon tube of the large number of cobalt or cobalt alloy-containing carbon composites was 45%. Table 1 below shows the average filling rate of cobalt carbide calculated by observing a plurality of fields of TEM observation images of the obtained cobalt or cobalt alloy inclusion carbon composite. The R value calculated from X-ray diffraction was 0.58.
[0128]
[Table 1]

[0129]
A clear electron diffraction pattern was observed for the inclusions, and the inclusions had high crystallinity. As a result of TEM observation, the crystallization rate of the inclusion (ratio of the area of the TEM image of crystalline cobalt carbide to the area of the TEM image in the range in which cobalt carbide was filled) was about 100%.
[0130]
In the carbonaceous material obtained in Example 1, the carbon wall surface is not nested or scrolled, but appears to be patchwork (so-called paper mache or cord), and the nano-flakes carbon tube Met.
[0131]
The shape of the nano flake carbon tube constituting the cobalt or cobalt alloy inclusion carbon composite obtained in this example is cylindrical, and the graphene sheet image observed in the cross-sectional TEM photograph across the longitudinal direction is It was not a closed ring, but a discontinuous ring with many discontinuities.
[0132]
In addition, when the nano flake carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is observed by TEM, a number of substantially linear graphene sheet images oriented in the longitudinal direction are individually The length of the graphene sheet image was generally in the range of 2 to 30 nm.
[0133]
Example 2
The reaction apparatus as shown in FIG. 1 was used to obtain the cobalt or cobalt alloy-containing carbon composite of the present invention as follows.
[0134]
Process (1)
CoCl₂・ 4H₂Spread 0.2 g of O (manufactured by Kanto Chemical Co., Ltd.) thinly in a nickel boat. This is installed in the center of the furnace made of quartz tube, and the inside of the furnace is depressurized to a pressure of 50 Pa. At this time, argon gas containing 5000 ppm of oxygen is supplied at a rate of 10 ml / min from the side opposite to the end of the reaction furnace to which the vacuum suction line is attached (left side of the reaction tube in FIG. 1). As a result, the ratio B / A when the internal volume of the reactor is A (rill) and the oxygen amount is B (Ncc) is 6 × 10 6.^-3It was. Next, the temperature is raised to 1000 ° C. with reduced pressure.
[0135]
Process (2)
When the temperature reached 1000 ° C., argon was introduced and the pressure was 6.7 × 10 6.^FourControl to Pa. On the other hand, as a pyrolytic carbon source, argon gas was bubbled into a benzene tank, and a mixed gas of volatilized benzene and argon was introduced into the furnace at a flow rate of 60 ml / min per 1 liter of reactor volume, and diluted gas As described above, argon gas is introduced at a flow rate of 40 ml / min.
[0136]
By reacting at a reaction temperature of 1000 ° C. for 90 minutes, the temperature is lowered to 500 ° C. in 20 minutes, and then the heater is removed and air-cooled to room temperature in 20 minutes. 200 mg of material was obtained.
[0137]
From the results of SEM observation, the carbon or cobalt alloy-containing carbon composite constituting the obtained carbonaceous material was 20 to 40 nm in diameter and 3 to 5 microns in length, and was highly linear. Moreover, the thickness of the wall part which consists of carbon was 2-10 nm, and was substantially uniform over the full length. Further, it was confirmed from the TEM observation and the X-ray diffraction method that the wall portion was a nanoflake carbon tube having a graphite structure having an average distance (d002) between carbon network surfaces of 0.34 nm or less.
[0138]
When a large number of cobalt or cobalt alloy-containing carbon composites constituting the carbonaceous material of the present invention were observed with an electron microscope (TEM), the space portion of the nanoflake carbon tube (enclosed by the tube wall of the nanoflake carbon tube) Cobalt or cobalt alloy inclusion carbon composites having various filling ratios in the range of 10 to 80% in the space) were mixed.
[0139]
From the results of TEM observation, in the carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, the average filling rate into the space portion in the nanoflakes carbon tube was 45% (average value as a carbonaceous material). It was. The R value calculated from X-ray diffraction in the same manner as in Example 1 was 0.48.
[0140]
Regarding the inclusion, a clear electron diffraction pattern was observed, and it was found that the inclusion had high crystallinity. As a result of TEM observation, the crystallization rate of the inclusion was about 100%.
[0141]
The shape of the nano flake carbon tube constituting the cobalt or cobalt alloy inclusion carbon composite obtained in this example is cylindrical, and the graphene sheet image observed in the cross-sectional TEM photograph across the longitudinal direction is It was not a closed ring, but a discontinuous ring with many discontinuities.
[0142]
In addition, when the nano flake carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is observed by TEM, a number of substantially linear graphene sheet images oriented in the longitudinal direction are individually The length of the graphene sheet image was generally in the range of 2 to 30 nm.
[0143]
Example 3
Using the apparatus shown in FIG. 2, the following steps (1) and (2) were carried out to obtain the cobalt or cobalt alloy-containing carbon composite of the present invention.
[0144]
Process (1)
Anhydrous CoCl₂Spread 0.2 g (manufactured by Kanto Chemical Co., Ltd.) thinly in a porcelain boat. This is installed downstream in the furnace. In addition, dicyclopentadienyl cobalt placed in a porcelain boat is installed upstream in the furnace.
[0145]
The pressure in the furnace is reduced to 50 Pa. At this time, argon gas containing 5000 ppm oxygen is supplied at a rate of 50 ml / min from the opposite side of the vacuum suction line. Accordingly, the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 6 × 10 6.^-3It was. Next, the temperature is raised to 1000 ° C. with reduced pressure.
[0146]
Process (2)
When the reaction temperature reaches 1000 ° C., argon is introduced and the pressure is 6.7 × 10 6.^FourControl to Pa. On the other hand, dicyclopentadienyl cobalt in a porcelain boat installed on the upstream side of the furnace is 6.7 × 10^FourThe temperature is raised to Pa.
[0147]
In addition, argon gas was bubbled into the benzene tank as a pyrolytic carbon source, and a mixed gas of volatilized benzene and argon was introduced into the furnace at a flow rate of 60 ml / min per liter of reactor volume, and diluted gas As described above, argon gas is introduced at a flow rate of 40 ml / min. The reaction was carried out at a reaction temperature of 1000 ° C. for 90 minutes.
[0148]
Next, after the temperature was lowered to 500 ° C. in 20 minutes, the heater was removed and air-cooled to room temperature in 20 minutes to obtain 400 mg of carbonaceous material containing cobalt or a cobalt alloy-containing carbon composite in the reaction tube.
[0149]
From the results of SEM observation, the obtained cobalt or cobalt alloy-containing carbon composite was 20 to 40 nm in diameter and 3 to 5 microns in length and was highly linear.
[0150]
Moreover, the thickness of the wall part which consists of carbon was 5-15 nm, and was substantially uniform over the full length. Further, it was confirmed from the TEM observation and the X-ray diffraction method that the wall portion was a nanoflake carbon tube having a graphite structure having an average distance (d002) between carbon network surfaces of 0.34 nm or less.
[0151]
When a large number of cobalt or cobalt alloy-containing carbon composites constituting the carbonaceous material of the present invention were observed with an electron microscope (TEM), the space part of the nanoflake carbon tube (enclosed by the carbon wall of the nanoflake carbon tube) Cobalt or cobalt alloy-containing carbon composites having various filling ratios in the range of 25 to 90% in the space) were mixed.
[0152]
A clear electron diffraction pattern was observed for the inclusion, and the inclusion had high crystallinity. As a result of TEM observation, the crystallization rate of the inclusion was about 100%.
[0153]
From the result of TEM observation, in the carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, the average filling rate (average value as the carbonaceous material) into the space portion in the nanoflakes carbon tube was 70%. It was. The R value calculated from X-ray diffraction in the same manner as in Example 1 was 3.5.
[0154]
The shape of the nano flake carbon tube constituting the cobalt or cobalt alloy inclusion carbon composite obtained in this example is cylindrical, and the graphene sheet image observed in the cross-sectional TEM photograph across the longitudinal direction is It was not a closed ring, but a discontinuous ring with many discontinuities.
[0155]
In addition, when the nano flake carbon tube constituting the cobalt or cobalt alloy-encapsulating carbon composite of the present invention is observed by TEM, a number of substantially linear graphene sheet images oriented in the longitudinal direction are individually The length of the graphene sheet image was generally in the range of 2 to 30 nm.
[0156]
Example 4
In the reaction apparatus as shown in FIG. 1, the reaction tube was made of carbon and used with enhanced heat resistance, and the cobalt or cobalt alloy-encapsulating carbon composite of the present invention was obtained as follows.
[0157]
Process (1)
Anhydrous CoCl₂Spread 0.2 g (manufactured by Kanto Chemical Co., Ltd.) thinly in a porcelain boat. This is installed in the center of the furnace made of quartz tube, and the inside of the furnace is depressurized to a pressure of 50 Pa. At this time, argon gas containing 5000 ppm oxygen is supplied at a rate of 5 ml / min from the opposite side of the vacuum suction line. Thus, the ratio B / A when the internal volume of the reactor is A (liter) and the oxygen amount is B (Ncc) is 2.5 × 10^-3It was. Next, the temperature is raised to 1000 ° C. with reduced pressure.
[0158]
Process (2)
When the temperature reached 1000 ° C., argon was introduced and the pressure was 6.7 × 10 6.^FourControl to Pa. On the other hand, as a pyrolytic carbon source, argon gas was bubbled into a benzene tank, and a mixed gas of volatilized benzene and argon was introduced into the furnace at a flow rate of 30 ml / min per liter of reactor volume, and diluted gas As described above, argon gas is introduced at a flow rate of 20 ml / min.
[0159]
After reacting at a reaction temperature of 1000 ° C. for 120 minutes, the pressure is reduced to 50 Pa at 1000 ° C. Then 9.0 x 10 in argon atmosphere^FourThe temperature inside the furnace was raised to 1400 ° C. in 120 minutes, maintained at 1400 ° C. for 6 hours, cooled to 500 ° C. in 24 hours, removed from the heater and allowed to cool to room temperature. 180 mg of a carbonaceous material containing a cobalt alloy-containing carbon composite was obtained.
[0160]
From the results of SEM observation, the carbon or cobalt alloy-containing carbon composite constituting the obtained carbonaceous material was 20 to 50 nm in diameter, 2 to 5 microns in length, and highly linear. Moreover, the thickness of the wall part which consists of carbon was 2-10 nm, and was substantially uniform over the full length. Further, it was confirmed from the TEM observation and the X-ray diffraction method that the wall portion was a nested multi-walled carbon nanotube having a graphite structure having an average distance (d002) between carbon network surfaces of 0.34 nm or less.
[0161]
When a large number of cobalt or cobalt alloy-containing carbon composites constituting the carbonaceous material of the present invention were observed with an electron microscope (TEM), the space of the nested multi-walled carbon nanotubes (the tube wall of the nested multi-walled carbon nanotubes) Cobalt or cobalt alloy-encapsulated carbon composites having various filling ratios in the range of 10 to 50% in the space surrounded by) were mixed.
[0162]
A clear electron diffraction pattern was observed for the inclusions, and the inclusions had high crystallinity. As a result of TEM observation, the crystallization rate of the inclusion was about 100%.
[0163]
From the results of TEM observation, in the carbonaceous material containing the cobalt or cobalt alloy-encapsulating carbon composite of the present invention, the average filling rate into the inner space of the multi-walled carbon nanotube of the nested structure is 20% (average value as the carbonaceous material) Met. The R value calculated from X-ray diffraction in the same manner as in Example 1 was 0.38.
[0164]
【The invention's effect】
According to the present invention, the following remarkable effects are achieved.
[0165]
According to the production method of the present invention, a cobalt or cobalt alloy-encapsulating carbon composite having a novel configuration in which 10 to 90% of a space surrounded by a wall of a carbon material is filled with cobalt or a cobalt alloy can be easily obtained. Can be obtained in high yields and in large quantities.
[0166]
The obtained cobalt or cobalt alloy-containing carbon composite is clearly different in structure from a known material in which cobalt is present at the tip of the carbon nanotube in that cobalt or cobalt alloy is included in 10 to 90% of the space. It is a novel material having a novel and unique property based on a unique structure.
[0167]
In addition, since the cobalt or cobalt alloy-encapsulating carbon composite of the present invention has a metal encapsulated in a space surrounded by a graphite wall having excellent durability, a semi-permanent conductor or molecule that hardly causes deterioration in characteristics. It has functions as a conductive wire and a magnetic or molecular magnet.
[0168]
Therefore, the cobalt or cobalt alloy-encapsulating carbon composite according to the present invention includes an electron emission material, a cobalt sustained-release material, a magnetic recording material, a sliding material, a conductive fibril, a magnetic material, a magnetic fluid, a superconducting material, an abrasion resistant material. It is extremely useful as a conductive material, a semiconductor material, and the like.
[0169]
In addition, in the present invention, the entire space inside the carbon tube is not filled with cobalt or a cobalt alloy as an inclusion, but 10 to 90% of the space is filled, so that the manufacturing is easy. Compared with a material composed of carbon nanotubes alone, it is excellent in that it has high electrical conductivity, can impart magnetism, and can expect nano-sized quantum effects.
[0170]
In addition, since the inclusion rate of cobalt or cobalt alloy which is inclusion can be produced in the range of 10 to 90% of the space inside the carbon tube, the cobalt or cobalt alloy inclusion carbon composite of the present invention having a specific inclusion rate can be obtained. By selecting the carbonaceous material to be included, various physical properties such as electrical characteristics, magnetic characteristics, and specific gravity can be controlled.
[0171]
Regarding the specific gravity, the composite with 100% inclusion rate, that is, a metal containing cobalt or the like over the entire length of the carbon tube, is too high due to the inclusion metal, Uniform dispersion in other materials may be difficult. However, since the cobalt or cobalt alloy-encapsulating carbon composite of the present invention can reduce the amount of encapsulated metal within the range of the encapsulation rate of 10 to 90%, uniform mixing is facilitated.
[0172]
In particular, the nano-flake carbon tube of the present invention and cobalt or a cobalt alloy-containing carbon composite made of cobalt or a cobalt alloy have the following advantages.
(a) There are many starting points of electron emission. Since there is a high possibility of electron emission from the edge of the graphene sheet, it is advantageous from the viewpoint of obtaining a large current density.
(b) Excellent in life characteristics due to its high graphitic properties.
(c) Become familiar with the paste. When the graphitization is high, the compatibility with the solvent and the paste agent becomes worse at the time of pasting, but the nano-flake carbon tube and cobalt or cobalt alloy-containing carbon composite made of cobalt or cobalt alloy have the effect of the edge of the graphene sheet. Therefore, pasting is easy.
(d) Good heat dissipation.
(e) Structure control is easy. Since the side wall has a flake shape or a tension shape, structure control such as cutting and surface modification becomes easy.
(f) Flexible. Since the side wall is flake-like or tension-like, flexibility is imparted, and when used as a composite material, both rigidity and impact resistance can be achieved.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a production apparatus for performing the production method of the present invention.
FIG. 2 is a schematic view showing another example of a production apparatus for performing the production method of the present invention.
FIG. 3 shows a schematic diagram of a TEM image of a carbon tube, (a-1) is a schematic diagram of a TEM image of a cylindrical nanoflaked carbon tube, and (a-2) is a multi-layer carbon nanotube with a nested structure It is a schematic diagram of TEM image.
[Explanation of symbols]
1 reactor
2 Heating device
3 Heating device
100 TEM image of nano flake carbon tube in the longitudinal direction
110 Nearly straight graphene sheet image
200 TEM image of cross section almost perpendicular to the longitudinal direction of the nano flake carbon tube
210 Arc graphene sheet image
300 Straight graphene sheet image continuous over the entire length in the longitudinal direction of a multi-walled carbon nanotube with a nested structure
400 TEM image of a cross section perpendicular to the longitudinal direction of a multi-walled carbon nanotube with a nested structure

Claims (17)

(a) and the nano flakes carbon tubes
(b) consisting of cobalt or a cobalt alloy ,
The cobalt or cobalt alloy containing carbon composites 10 to 90% of the space surrounded by the tube wall of the nanoflake carbon tube cobalt or cobalt alloy (b) described above is characterized in that it is filled in (a) . It is straight, the outer diameter is 1 to 100 nm, the thickness of the wall portion made of carbon is 49 nm or less and substantially uniform over the entire length, the length is L, and the outer diameter is D. 2. The cobalt or cobalt alloy-containing carbon composite according to claim 1, wherein the aspect ratio L / D is 5 to 10,000. The average distance (d002) between carbon network surfaces is 0.34 nm or less when the wall portion of the nanoflake carbon tube constituting the cobalt or cobalt alloy-containing carbon composite is measured by X-ray diffraction. Or the cobalt or cobalt alloy inclusion carbon composite of 2. The cobalt alloy contains at least 55% by weight of cobalt and is at least one selected from the group consisting of carbon, Ni, Fe, Cu, Mn, Cr, Pb, Zn, Mo, Al, Ti, Nb, Ta, S, and Si. The cobalt or cobalt alloy-containing carbon composite according to any one of claims 1 to 3 , which is an alloy further containing a seed. (a) and the nano flakes carbon tubes
(b) consisting of cobalt or a cobalt alloy,
Carbonaceous material containing cobalt or cobalt alloy containing carbon composites cobalt or a cobalt alloy of the (b) 10 to 90% of the space surrounded by the tube wall of the nanoflake carbon tubes (a) above are filled . In a powder X-ray diffraction measurement in which an irradiation area of 25 mm ² or more is irradiated with respect to 1 mg of a carbonaceous material, 40 ° <2θ <attributed to cobalt or a cobalt alloy included in the nanoflake carbon tube. The integrated intensity of the peak showing the strongest integrated intensity among the peaks at 50 ° is Ia, and the integrated intensity of the peak at 26 ° <2θ <27 ° attributed to the average distance (d002) between the carbon network surfaces of the carbon tubes. The carbonaceous material according to claim 5 , wherein the ratio R of Ia / Ib is 0.3 to 4.4, where Ib is Ib. The cobalt or cobalt alloy-encapsulating carbon composite is linear, has an outer diameter of 1 to 100 nm, has a wall thickness of 49 nm or less, and is substantially uniform over the entire length. The carbonaceous material according to claim 5 or 6 , wherein the aspect ratio L / D is 5 to 10,000 when the thickness is L and the outer diameter is D. The wall of the nanoflake carbon tubes constituting the cobalt or cobalt alloy containing carbon composite as determined by X-ray diffraction method, according to claim 5 average distance between the hexagonal carbon layer (d002) is not more than 0.34nm carbonaceous material according to any one of 1 to 7. The cobalt alloy contains at least 55% by weight of cobalt and is at least one selected from the group consisting of carbon, Ni, Fe, Cu, Mn, Cr, Pb, Zn, Mo, Al, Ti, Nb, Ta, S, and Si. The carbonaceous material according to any one of claims 5 to 8 , which is an alloy further containing a seed. (a) a carbon tube selected from the group consisting of nano flake carbon tubes and nested multi-walled carbon nanotubes;
(b) consisting of cobalt or a cobalt alloy,
Production of carbonaceous material comprising a cobalt or cobalt alloy containing carbon composites cobalt or a cobalt alloy of the (b) 10 to 90% of the space surrounded by the tube wall of the carbon tube (a) above are filled A method,
(1) Ratio when the pressure is adjusted to 10 ⁻⁵ Pa to 200 kPa in an inert gas atmosphere, the oxygen concentration in the reactor is A (liter), and the oxygen amount is B (Ncc). The B / A is adjusted to a concentration of 1 × 10 ⁻¹⁰ to 1 × 10 ⁻¹ and the cobalt halide is heated to 600 to 1100 ° C. in the reaction furnace, or (a) cobalt halide and ( b) Iron halide, nickel halide, copper halide, manganese halide, chromium halide, lead halide, zinc halide, molybdenum halide, aluminum halide, titanium halide, niobium halide, tantalum halide, Heating at least one selected from the group consisting of sulfur halides and silicon halides to 600-1100 ° C., and
(2) including a step of adjusting the pressure to 10 ⁻⁵ Pa to 200 kPa with the inside of the reaction furnace as an inert gas atmosphere, introducing a pyrolytic carbon source, and performing heat treatment at 600 to 1100 ° C. Manufacturing method. After the heat treatment step of the step (2), the nano flake carbon tube and cobalt or a cobalt alloy filled in 10 to 90% of the space in the tube by cooling to 50 to 2000 ° C./h to 500 ° C. The manufacturing method of Claim 10 which produces | generates the carbonaceous material containing a cobalt or cobalt alloy inclusion carbon composite. After the heat treatment step of step (2),
(3) A step of replacing the inside of the reactor with an inert gas while maintaining the temperature of step (2),
(4) a step of raising the temperature of the inside of the reactor substituted with an inert gas to 1100 to 1450 ° C., (5) a step of maintaining the end point temperature at the end point of the temperature rise until a multi-layer carbon nanotube having a nested structure is formed,
(6) The reaction furnace is made of cobalt or a cobalt alloy filled in 10 to 90% of the multi-walled carbon nanotube with a nested structure by performing a process of cooling the reactor at a rate of 50 ° C./h or less. The manufacturing method of Claim 10 which produces | generates the carbonaceous material containing a cobalt or cobalt alloy inclusion carbon composite. The manufacturing method of Claim 10 which performs the heat processing of a process (2) in presence of an organic cobalt complex. The production method according to claim 13 , wherein the organic cobalt complex is dicyclopentadienyl cobalt or a cobalt carbonyl complex. The method according to any one of claims 10 to 14 , wherein the cobalt halide is a chloride of cobalt. Cobalt chloride is composed of CoCl ₂ , CoCl ₂ · H ₂ O, CoCl ₂ · 1.5H ₂ O, CoCl ₂ · 2H ₂ O, CoCl ₂ · 4H ₂ O, CoCl ₂ · 6H ₂ O and CoCl ₃ The production method according to claim 15 , which is at least one selected from the group consisting of: The thermally decomposable carbon source is at least one selected from the group consisting of aromatic hydrocarbons having 6 to 12 carbon atoms, saturated aliphatic hydrocarbons having 1 to 10 carbon atoms, and unsaturated aliphatic hydrocarbons having 2 to 5 carbon atoms. the process according to any one of claims 10 to 16, which is a species.

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