JP2015063442A - Method for manufacturing carbon nanotube-containing composition - Google Patents
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Abstract
Description
本発明はカーボンナノチューブ含有組成物の製造方法に関する。 The present invention relates to a method for producing a carbon nanotube-containing composition.
カーボンナノチューブは、その理想的な一次元構造に起因する様々な特性、例えば良電気伝導性、熱伝導性や力学強度などによって様々な工業的応用が期待されている物質であり、直径、層数、長さを制御することにより、それぞれの用途での性能向上および応用性の広がりも期待されている。 Carbon nanotubes are materials that are expected to have various industrial applications due to various properties resulting from their ideal one-dimensional structure, such as good electrical conductivity, thermal conductivity, and mechanical strength. By controlling the length, it is expected to improve the performance and expand the applicability in each application.
また、カーボンナノチューブは、通常層数の少ない方が高グラファイト構造を有し、単層カーボンナノチューブや二層カーボンナノチューブは高グラファイト構造を有しているために導電性や熱伝導性などの特性も高いことが知られている。特にカーボンナノチューブの中でも層数の比較的少ない２〜５層カーボンナノチューブは単層カーボンナノチューブの特性と多層カーボンナノチューブの両方の特性を有しているために、種々の用途において有望な素材として注目を集めている。 Carbon nanotubes usually have a high graphite structure when the number of layers is small, and single-walled carbon nanotubes and double-walled carbon nanotubes have a high graphite structure. It is known to be expensive. In particular, among carbon nanotubes, 2 to 5 carbon nanotubes, which have a relatively small number of layers, have the characteristics of both single-walled carbon nanotubes and multi-walled carbon nanotubes. Therefore, they attract attention as promising materials in various applications. Collecting.
従来のカーボンナノチューブの製造方法としては、レーザーアブレーション法、アーク放電法、化学気相成長法（ＣＶＤ（ＣｈｅｍｉｃａｌＶａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ）法）などによる合成が知られている（非特許文献１参照）。特に炭素源となるガスを熱分解してカーボンナノチューブを製造するＣＶＤ法では、カーボンナノチューブを大量に合成することが可能となる。 As a conventional method for producing a carbon nanotube, synthesis by a laser ablation method, an arc discharge method, a chemical vapor deposition method (CVD (Chemical Vapor Deposition) method) or the like is known (see Non-Patent Document 1). In particular, in the CVD method in which a carbon source is pyrolyzed to produce carbon nanotubes, a large amount of carbon nanotubes can be synthesized.
このＣＶＤ法にて、炭素源を予熱して金属触媒と接触させることでカーボンナノチューブを製造する方法が知られている（特許文献１参照）。特許文献１は基板上に配向カーボンナノチューブを形成させる製造方法で、基板法ということもあり、カーボンナノチューブを効率よく高収量で得られるものではない。また、炭素源濃度が高いことから、炭素副生物を生成しやすく、カーボンナノチューブの品質低下の問題を招く。 In this CVD method, a method of producing carbon nanotubes by preheating a carbon source and bringing it into contact with a metal catalyst is known (see Patent Document 1). Patent Document 1 is a manufacturing method in which oriented carbon nanotubes are formed on a substrate, sometimes referred to as a substrate method, and carbon nanotubes cannot be obtained efficiently and in high yield. Moreover, since the carbon source concentration is high, it is easy to produce carbon by-products, resulting in a problem of quality degradation of the carbon nanotubes.
本発明は、上記のような事情に鑑みなされたものであり、ＣＶＤ法にて品質の高いカーボンナノチューブを高収量で得ることができるカーボンナノチューブ含有組成物の製造方法を提供することを目的とする。 This invention is made | formed in view of the above situations, and it aims at providing the manufacturing method of the carbon nanotube containing composition which can obtain a high quality carbon nanotube by a CVD method by high yield. .
本発明者らは、上記課題を解決するために鋭意検討を行った結果、ＣＶＤ法にて炭素含有組成物を予熱し、炭素含有組成物の分解を促進させてから金属触媒等のカーボンナノチューブ製造用触媒体と接触させることで品質の高いカーボンナノチューブを高収量で製造し得ることを見出し、本発明を完成するに至った。
第１の発明は、９００℃以上１２００℃未満に予熱された炭素含有組成物を予熱温度以下でカーボンナノチューブ製造用触媒体と接触、反応させることからなるカーボンナノチューブ含有組成物の製造方法である。
第２の発明は、前記予熱された炭素含有組成物をカーボンナノチューブ製造用触媒体と接触、反応させる温度が６００℃以上９５０℃以下の範囲であることを特徴とする。
第３の発明は、前記炭素含有組成物とキャリアガスを混合して使用し、炭素含有組成物の濃度が全ガス流量に対して１〜１０ｖｏｌ％の範囲であることを特徴とする。
第４の発明は、前記炭素含有組成物がメタン、エタン、エチレンから選ばれる少なくとも１種であることを特徴とする。
第５の発明は、前記カーボンナノチューブ製造用触媒体の粒径が０．２〜３ｍｍの範囲であり、且つかさ密度が０．１〜１ｇ／ｍＬの範囲であることを特徴とする。
第６の発明は、前記カーボンナノチューブ製造用触媒体に含まれる金属触媒が８〜１０族の遷移金属から選ばれる少なくとも１種であることを特徴とする。
As a result of intensive studies to solve the above problems, the present inventors pre-heated the carbon-containing composition by the CVD method, and promoted the decomposition of the carbon-containing composition before producing carbon nanotubes such as metal catalysts. It has been found that high quality carbon nanotubes can be produced in high yield by contacting with the catalyst body for use, and the present invention has been completed.
The first invention is a method for producing a carbon nanotube-containing composition comprising contacting and reacting a carbon-containing composition preheated to 900 ° C. or higher and lower than 1200 ° C. with a catalyst body for producing carbon nanotubes at a preheating temperature or lower.
The second invention is characterized in that the temperature at which the preheated carbon-containing composition is brought into contact with and reacted with the carbon nanotube production catalyst body is in the range of 600 ° C. to 950 ° C.
3rd invention mixes and uses the said carbon containing composition and carrier gas, The density | concentration of a carbon containing composition is the range of 1-10 vol% with respect to the total gas flow volume, It is characterized by the above-mentioned.
The fourth invention is characterized in that the carbon-containing composition is at least one selected from methane, ethane, and ethylene.
The fifth invention is characterized in that a particle diameter of the carbon nanotube production catalyst body is in a range of 0.2 to 3 mm and a bulk density is in a range of 0.1 to 1 g / mL.
The sixth invention is characterized in that the metal catalyst contained in the carbon nanotube production catalyst body is at least one selected from Group 8-10 transition metals.
本発明により品質の高いカーボンナノチューブを高収量で得ることができる。 According to the present invention, high quality carbon nanotubes can be obtained in high yield.
次に本発明を詳細に説明する。 Next, the present invention will be described in detail.
本発明において、炭素含有組成物はカーボンナノチューブ製造の原料として用い、特に限定されないが、好ましくは炭化水素を用いるとよく、メタン、エタン、エチレン、プロパン、ブタン、ベンゼン、トルエン、キシレン等から選ばれる少なくとも１種である。メタン、エタン、エチレンが、単層または２層カーボンナノチューブを作りやすいので、より好ましい。 In the present invention, the carbon-containing composition is used as a raw material for producing carbon nanotubes, and is not particularly limited. However, a hydrocarbon is preferably used, and is selected from methane, ethane, ethylene, propane, butane, benzene, toluene, xylene, and the like. At least one. Methane, ethane, and ethylene are more preferable because they easily make single-walled or double-walled carbon nanotubes.
本発明において、カーボンナノチューブ製造用触媒体と接触させる前に炭素含有組成物を９００℃以上１２００℃未満に予熱する。予熱温度が９００℃以上では炭素含有組成物の分解が促進されやすくなり、カーボンナノチューブを速やかに、効率よく得ることができる。また、予熱温度が１２００℃未満では炭素含有組成物の分解が進みすぎず、カーボンナノチューブ製造用触媒体と接触する際に炭素副生物を生成しにくくなり、純度の高いカーボンナノチューブが得られやすくなる。よって、炭素含有組成物の予熱温度は、さらに好ましくは９００℃以上、１０００℃以下の範囲である。 In this invention, before making it contact with the catalyst body for carbon nanotube manufacture, a carbon containing composition is preheated to 900 degreeC or more and less than 1200 degreeC. When the preheating temperature is 900 ° C. or higher, decomposition of the carbon-containing composition is easily promoted, and carbon nanotubes can be obtained quickly and efficiently. In addition, when the preheating temperature is less than 1200 ° C., the decomposition of the carbon-containing composition does not proceed excessively, and it becomes difficult to produce carbon by-products when contacting the carbon nanotube production catalyst body, and it becomes easy to obtain high-purity carbon nanotubes. . Therefore, the preheating temperature of the carbon-containing composition is more preferably in the range of 900 ° C. or higher and 1000 ° C. or lower.
本発明において、カーボンナノチューブ含有組成物製造用触媒体とは炭素含有組成物の接触により、カーボンナノチューブ含有組成物を製造する触媒であり、特に限定されないが、例えば８族〜１０族の遷移金属化合物が担体上に担持された総体物または該金属化合物と担体の混合物を用いることができる。中でも、Ｆe、 Ｃｏ、Ｎｉ、Ｐｄ、Ｐｔ、Ｒｈ等が特に好ましい。ここで金属とは、０価の状態とは限らない。反応中では０価の金属状態になっていると推定できるが、広く金属を含む化合物又は金属種という意味で解釈してよい。また遷移金属は微粒子であることが好ましい。微粒子とは粒径が０．５〜１０ｎｍであることが好ましい。金属が微粒子であると細いカーボンナノチューブが生成しやすい。金属は１種類だけを含んでいても、２種類以上を含んでいてもよい。２種類以上の金属を使用する場合、その比率は限定されない。２種類の金属を担持させる場合は、Ｆe、Ｃｏ、Ｎｉ、Ｐｄ、Ｐｔ、Ｒｈから選択される金属と選択されたそれ以外の金属の組み合わせが特に好ましい。特にＦｅとＣｏ、Ｎｉ、Ｖ、Ｍｏ、Ｐｄの１種以上とを組み合わせる場合が最も好ましい。また、他の成分が配合された組成物、あるいは他の成分と複合した複合体中に含まれる場合でも該金属化合物が担体上に担持または混合されていれば、触媒体として用いることができる。触媒体には、触媒体の１次粒子や２次粒子が凝集した状態も含まれる。 In the present invention, the catalyst body for producing a carbon nanotube-containing composition is a catalyst for producing a carbon nanotube-containing composition by contact with the carbon-containing composition, and is not particularly limited. Can be used as a whole or a mixture of the metal compound and the carrier supported on the carrier. Of these, Fe, Co, Ni, Pd, Pt, Rh and the like are particularly preferable. Here, the metal is not necessarily a zero-valent state. Although it can be presumed that the metal is in a zero-valent state during the reaction, it may be interpreted in the meaning of a compound containing a metal or a metal species. The transition metal is preferably fine particles. The fine particles preferably have a particle size of 0.5 to 10 nm. If the metal is fine particles, thin carbon nanotubes are likely to be generated. The metal may contain only 1 type, or may contain 2 or more types. When two or more kinds of metals are used, the ratio is not limited. When two kinds of metals are supported, a combination of a metal selected from Fe, Co, Ni, Pd, Pt, and Rh and the other metal selected is particularly preferable. In particular, the combination of Fe and one or more of Co, Ni, V, Mo, and Pd is most preferable. Further, even when it is contained in a composition containing other components or in a composite complexed with other components, it can be used as a catalyst body if the metal compound is supported or mixed on a carrier. The catalyst body includes a state in which primary particles and secondary particles of the catalyst body are aggregated.
本発明において反応方式は特に限定しないが、縦型流動床型反応器を用いて反応させることが好ましい。縦型流動床型反応器とは、原料となる炭素含有組成物（以下、炭素源と称する）が、鉛直方向（以下「縦方向」と称する場合もある）に流通するように設置された反応器である。該反応器の一方の端部から他方の端部に向けた方向に炭素源が流通し、触媒体層を通過する。反応器は、例えば管形状を有する反応器を好ましく用いることができる。なお、上記において、鉛直方向とは、鉛直方向に対して若干傾斜角度を有する方向をも含む（例えば水平面に対し９０°±１５°、好ましくは９０°±１０°）。なお、好ましいのは鉛直方向である。なお、炭素源の供給部および排出部は、必ずしも反応器の端部である必要はなく、炭素源が前記方向に流通し、その流通過程で触媒体層を通過すればよい。 In the present invention, the reaction method is not particularly limited, but the reaction is preferably carried out using a vertical fluidized bed reactor. A vertical fluidized bed reactor is a reaction in which a carbon-containing composition (hereinafter referred to as a carbon source) as a raw material flows in a vertical direction (hereinafter also referred to as “longitudinal direction”). It is a vessel. A carbon source flows in the direction from one end of the reactor toward the other end and passes through the catalyst layer. As the reactor, for example, a reactor having a tube shape can be preferably used. In the above, the vertical direction includes a direction having a slight inclination angle with respect to the vertical direction (for example, 90 ° ± 15 °, preferably 90 ° ± 10 ° with respect to the horizontal plane). The vertical direction is preferable. The carbon source supply section and the discharge section do not necessarily have to be end portions of the reactor, and the carbon source may circulate in the above-described direction and pass through the catalyst body layer in the circulation process.
触媒体は縦型流動床型反応器中、反応器の水平断面方向全面に存在させた状態にあり、反応時には流動床を形成した状態とする。このようにすることにより、触媒体と炭素源を有効に接触させることができる。横型反応器の場合、触媒体と炭素源を有効に接触させるため、炭素源の流れに対して垂直方向で反応器の断面全面に存在させた状態にするには、重力がかかる関係上、触媒体を左右から挟み込む必要がある。しかし、カーボンナノチューブ含有組成物の生成反応の場合、反応するに従って触媒体上にカーボンナノチューブ含有組成物が生成して、触媒体の体積が増加するので、左右から触媒体を挟みこむ方法は好ましくない。また、横型で流動床を形成させることも難しい。本発明では反応器を縦型にし、反応器内にガスが透過できる台を設置して、その上に触媒体を置くことによって、触媒体を両側から挟みこむことなく、反応器の断面方向に均一に触媒体を存在させることができ、炭素源を鉛直方向に流通させる際に流動床を形成させることもできる。触媒体を縦型流動床反応器の水平断面方向全面に存在させた状態とは、水平断面方向に全体に触媒体が広がっていて触媒体底部の台が見えない状態を言う。このような状態の好ましい実施態様としては、例えば、反応器内にガスが透過できる触媒体を置く台（セラミックスフィルターなど）を置き、そこに所定の厚みで触媒体を充填する。この触媒体層の上下が多少凸凹してもかまわない（図１）。図１は、反応器１０４の中に触媒体を置く台である石英焼結板１０３が設置され、その上に触媒体層１０５を形成する触媒体が反応器１０４の水平断面方向全体に存在している状態を示す概念図である。
In the vertical fluidized bed reactor, the catalyst body is in a state of being present on the entire surface in the horizontal sectional direction of the reactor, and a fluidized bed is formed during the reaction. By doing in this way, a catalyst body and a carbon source can be made to contact effectively. In the case of a horizontal reactor, in order to effectively bring the catalyst body and the carbon source into contact with each other, it is necessary to make contact with the entire surface of the reactor in a direction perpendicular to the flow of the carbon source. It is necessary to sandwich the medium from the left and right. However, in the case of the formation reaction of the carbon nanotube-containing composition, the carbon nanotube-containing composition is generated on the catalyst body as it reacts, and the volume of the catalyst body increases, so that the method of sandwiching the catalyst body from the left and right is not preferable. . It is also difficult to form a fluidized bed in the horizontal type. In the present invention, the reactor is set in a vertical type, a stage through which gas can permeate is installed in the reactor, and the catalyst body is placed thereon, so that the catalyst body is not sandwiched from both sides in the cross-sectional direction of the reactor. The catalyst body can be present uniformly, and a fluidized bed can be formed when the carbon source is circulated in the vertical direction. The state in which the catalyst body is present on the entire surface in the horizontal sectional direction of the vertical fluidized bed reactor refers to a state in which the catalyst body spreads out in the horizontal sectional direction and the platform at the bottom of the catalyst body cannot be seen. As a preferred embodiment of such a state, for example, a stage (ceramics filter or the like) on which a catalyst body that can pass a gas is placed in a reactor, and the catalyst body is filled with a predetermined thickness. The upper and lower sides of the catalyst layer may be slightly uneven (FIG. 1). In FIG. 1, a
流動床型は、触媒体を連続的に供給し、反応後の触媒体とカーボンナノチューブ含有組成物を含む集合体を連続的に取り出すことにより、連続的な合成が可能であり、カーボンナノチューブ含有組成物を効率よく得ることができ好ましい。 The fluidized bed type can continuously synthesize by continuously supplying the catalyst body and continuously removing the aggregate containing the catalyst body and the carbon nanotube-containing composition after the reaction. A product can be obtained efficiently, which is preferable.
流動床型反応において、炭素源と触媒体が均一に効率よく接触するためにカーボンナノチューブ合成反応が均一に行われ、アモルファスカーボンなどの不純物による触媒被覆が抑制され、触媒活性が長く続くと考えられる。 In the fluidized bed type reaction, the carbon nanotube synthesis reaction is performed uniformly in order for the carbon source and the catalyst body to contact uniformly and efficiently, the catalyst coating by impurities such as amorphous carbon is suppressed, and the catalyst activity is expected to continue for a long time. .
縦型反応器とは対照的に、横型反応器は横方向（水平方向）に設置された反応器内に、石英板上に置かれた触媒体が設置され、該触媒体上を炭素源が通過して接触、反応する態様の反応装置を指す。この場合、触媒体表面ではカーボンナノチューブが生成するが、触媒体内部には炭素源が到達しないため、縦型反応器に比較して収量が少なくなる傾向にある。これに対して、縦型反応器では触媒体全体に原料の炭素源が接触することが可能となるため、効率的に、多量のカーボンナノチューブ含有組成物を合成することが可能である。反応器は耐熱性であることが好ましく、石英製、アルミナ製等の耐熱材質からなることが好ましい。 In contrast to the vertical reactor, in the horizontal reactor, a catalyst body placed on a quartz plate is placed in a reactor placed in a horizontal direction (horizontal direction), and a carbon source is placed on the catalyst body. It refers to a reaction device that passes through, contacts and reacts. In this case, carbon nanotubes are generated on the surface of the catalyst body, but the carbon source does not reach the inside of the catalyst body, so the yield tends to be lower than that of the vertical reactor. On the other hand, in the vertical reactor, since the raw carbon source can be brought into contact with the entire catalyst body, a large amount of carbon nanotube-containing composition can be efficiently synthesized. The reactor is preferably heat resistant and is preferably made of a heat resistant material such as quartz or alumina.
本発明においては、前記温度範囲に予熱された炭素含有組成物は、予熱温度以下でカーボンナノチューブ製造用触媒体と接触、反応させる。これにより、品質の高いカーボンナノチューブの製造が高収量で可能になる。 In the present invention, the carbon-containing composition preheated to the above temperature range is brought into contact with and reacted with the carbon nanotube production catalyst body at a preheating temperature or lower. This makes it possible to produce high-quality carbon nanotubes with a high yield.
本発明において、前記の予熱された炭素含有組成物とカーボンナノチューブ製造用触媒体と接触、反応させる温度は６００℃以上、９５０℃以下の範囲が好ましく、８００℃以上９５０℃以下の範囲がより好ましい。反応温度が６００℃を超えるとカーボンナノチューブ含有組成物が高収量で得られやすくなり、９５０℃以下では炭素含有組成物の分解が進みすぎず、カーボンナノチューブ製造用触媒体と接触する際に炭素副生物を生成しにくくなり、純度の高いカーボンナノチューブを得られやすくなる。 In the present invention, the temperature at which the preheated carbon-containing composition and the carbon nanotube production catalyst body are contacted and reacted is preferably in the range of 600 ° C. or higher and 950 ° C. or lower, and more preferably in the range of 800 ° C. or higher and 950 ° C. or lower. . When the reaction temperature exceeds 600 ° C., the carbon nanotube-containing composition is easily obtained in a high yield, and when the reaction temperature is 950 ° C. or less, the decomposition of the carbon-containing composition does not proceed excessively, and when the carbon nanotube-containing composition comes into contact with the catalyst for carbon nanotube production, It becomes difficult to produce living organisms, and it becomes easier to obtain high-purity carbon nanotubes.
なお、炭素含有組成物の予熱温度と触媒体と接触、反応する温度の組み合わせは、反応温度が予熱温度と等しいか、予熱温度の方が高くなるように適宜調製する。例えば、予熱温度９００℃では反応温度は９００℃以下となるようにする。 Note that the combination of the preheating temperature of the carbon-containing composition and the temperature at which the catalyst body is brought into contact with and reacted is appropriately prepared so that the reaction temperature is equal to or higher than the preheating temperature. For example, when the preheating temperature is 900 ° C., the reaction temperature is set to 900 ° C. or less.
反応温度は予熱温度以下であれば良いが、カーボンナノチューブ（ＣＮＴ）収量の観点から、予熱温度が反応温度と等しいか、より高い方が好ましく、その差は０〜２００℃の範囲が好ましい。より好ましくは４０〜１５０℃の範囲であり、更に好ましくは７０〜１２０℃の範囲である。 The reaction temperature may be equal to or lower than the preheating temperature, but from the viewpoint of carbon nanotube (CNT) yield, the preheating temperature is preferably equal to or higher than the reaction temperature, and the difference is preferably in the range of 0 to 200 ° C. More preferably, it is the range of 40-150 degreeC, More preferably, it is the range of 70-120 degreeC.
本発明においては、炭素含有組成物を、予熱、触媒体と接触・反応させるために、炭素含有組成物以外のガスと混合させ反応器内を通過させることもできる。炭素含有組成物の濃度が全ガス流量に対して１〜１０ｖｏｌ％の範囲とすると、カーボンナノチューブ含有組成物を効率的に成長させやすくなる。炭素含有組成物の濃度が１０ｖｏｌ％以下であると、炭素副生物が生成しにくくなり、カーボンナノチューブの純度が高くなりやすく、その成長を阻害しにくくなり、収量が増大しやすくなる。一方、炭素含有組成物の濃度が１ｖｏｌ％以上であると、炭素源として必要な濃度となり好ましい。炭素含有組成物の濃度が３〜８ｖｏｌ％であるとより好ましい。炭素含有組成物の濃度が全ガス流量に対して１〜１０ｖｏｌ％となるようにキャリアガスを用いることができ、キャリアガスとして窒素、アルゴン、ヘリウム等が使用できる。 In the present invention, the carbon-containing composition can be mixed with a gas other than the carbon-containing composition and passed through the reactor in order to preheat and contact / react with the catalyst body. When the concentration of the carbon-containing composition is in the range of 1 to 10 vol% with respect to the total gas flow rate, the carbon nanotube-containing composition is easily grown efficiently. When the concentration of the carbon-containing composition is 10 vol% or less, carbon by-products are hardly generated, the purity of the carbon nanotubes is likely to be high, the growth thereof is difficult to be inhibited, and the yield is easily increased. On the other hand, when the concentration of the carbon-containing composition is 1 vol% or more, it is preferable because the concentration is necessary as a carbon source. More preferably, the concentration of the carbon-containing composition is 3 to 8 vol%. A carrier gas can be used so that the concentration of the carbon-containing composition is 1 to 10 vol% with respect to the total gas flow rate, and nitrogen, argon, helium, or the like can be used as the carrier gas.
カーボンナノチューブ製造用触媒体の粒径及びかさ密度は品質の高いカーボンナノチューブを得るために重要な要件である。
触媒体の粒径は０．２〜３ｍｍの範囲であることが好ましい。０．２ｍｍ未満の触媒体では、縦型反応器中で触媒体が大きく舞い上がり、触媒体が反応器の反応に適した加熱領域（均熱帯又は反応域）を外れることがあり、品質の高いカーボンナノチューブを得ることが困難になる。また３ｍｍより大きいと流動床中で触媒体が動きにくいため、炭素含有化合物が触媒体層の最も通りやすい箇所だけを通ってしまうという、いわゆるショートパスの問題が生じる。よって粒径の大きさは０．２〜３ｍｍの範囲が好ましく、さらに好ましくは０．５〜２．８ｍｍの範囲であり、最も好ましくは０．８５〜２．８ｍｍの範囲である。
なお、ここで粒径とは、篩い分け法により求めた粒径をいう。
The particle size and bulk density of the catalyst body for producing carbon nanotubes are important requirements for obtaining high-quality carbon nanotubes.
The particle size of the catalyst body is preferably in the range of 0.2 to 3 mm. If the catalyst body is less than 0.2 mm, the catalyst body greatly fluctuates in the vertical reactor, and the catalyst body may deviate from the heating zone (soaking zone or reaction zone) suitable for the reaction of the reactor. It becomes difficult to obtain nanotubes. On the other hand, if it is larger than 3 mm, the catalyst body is difficult to move in the fluidized bed, so that a so-called short path problem occurs in which the carbon-containing compound passes only through the most easily passing portion of the catalyst body layer. Therefore, the size of the particle size is preferably in the range of 0.2 to 3 mm, more preferably in the range of 0.5 to 2.8 mm, and most preferably in the range of 0.85 to 2.8 mm.
In addition, a particle size means the particle size calculated | required by the sieving method here.
触媒体の粒径を好ましい範囲とするためには篩い分けを行う方法、押し出し機から造粒する方法等を用いることができる。篩い分けの方法とは、触媒体の塊状物を粉砕しながら、篩いの目開き（ＪＩＳ Ｚ−８８０１−１（２００６）に準じた目開き）が例えば、０．５〜２．８ｍｍの篩いにかけて、０．５〜２．８ｍｍの間に留まった顆粒状の触媒体を回収する方法である。粉砕の方法はいかなる方法を用いても良い。 In order to make the particle size of the catalyst body within a preferable range, a method of sieving, a method of granulating from an extruder, or the like can be used. The method of sieving is to crush the lump of the catalyst body while passing through a sieve with a sieve opening (mesh according to JIS Z-8801-1 (2006)) of 0.5 to 2.8 mm, for example. , And recovering the granular catalyst body remaining between 0.5 and 2.8 mm. Any method of pulverization may be used.
また、押し出し機からの造粒方法では、触媒体と水を混練りし、内径が０．２〜３ｍｍの孔の開いた各種スクリーンから押し出す。得られた触媒体の線状凝集物を乾燥させながら粉砕し、その後篩い分けを行い、例えば、０．５〜２．８ｍｍの間にとどまった顆粒状の触媒体を回収する。上記、好ましい粒径とするには、篩いの目開きを適宜選択すればよい。 Moreover, in the granulation method from an extruder, a catalyst body and water are kneaded and extruded from various screens with holes having an inner diameter of 0.2 to 3 mm. The obtained linear aggregate of the catalyst body is pulverized while being dried, and then sieved, and for example, the granular catalyst body remaining between 0.5 and 2.8 mm is recovered. In order to obtain the above preferable particle diameter, the sieve opening may be appropriately selected.
触媒体のかさ密度が０．１〜１ｇ／ｍＬの範囲であることが好ましく、それにより、触媒体と炭素含有化合物との接触効率が良くなり、よりいっそう高い純度のカーボンナノチューブを効率よく、多量に合成することが可能となる。触媒体のかさ密度が０．１ｇ／ｍＬ未満では、触媒体を取り扱いづらいといった問題点がある。また、かさ密度が小さすぎると、炭素含有化合物と接触させる際に、縦型反応器中で触媒体が大きく舞い上がり、触媒体が反応器の均熱帯を外れることがあり、高品質なカーボンナノチューブを得ることが困難になる。一方で触媒のかさ密度が１ｇ／ｍＬを超えると、触媒体と炭素含有化合物とが均一に効率よく接触することが困難になり、やはり高品質のカーボンナノチューブを得ることが困難になる。触媒体のかさ密度が大きくなりすぎる場合、流動床中で触媒体が動きにくいために、炭素含有化合物を含むガスが触媒体層の最も通りやすい箇所だけを通ってしまうという、いわゆるショートパスの問題も生じる。 It is preferable that the bulk density of the catalyst body is in the range of 0.1 to 1 g / mL, whereby the contact efficiency between the catalyst body and the carbon-containing compound is improved, and carbon nanotubes of higher purity are efficiently and abundantly produced. Can be synthesized. When the bulk density of the catalyst body is less than 0.1 g / mL, there is a problem that it is difficult to handle the catalyst body. In addition, if the bulk density is too small, the catalyst body may be greatly swollen in the vertical reactor when contacting with the carbon-containing compound, and the catalyst body may deviate from the soaking zone of the reactor. It becomes difficult to obtain. On the other hand, when the bulk density of the catalyst exceeds 1 g / mL, it becomes difficult for the catalyst body and the carbon-containing compound to contact uniformly and efficiently, and it is also difficult to obtain high-quality carbon nanotubes. When the bulk density of the catalyst body becomes too large, the catalyst body is difficult to move in the fluidized bed, so that a gas containing a carbon-containing compound passes only through the most easily passable part of the catalyst body layer. Also occurs.
触媒体のかさ密度が上記の範囲であると触媒体が動くことによって、固定されたショートパスができにくく、炭素含有化合物と均一に接触することができる。よって触媒体のかさ密度は０．１〜１ｇ／ｍＬの範囲である。より好ましくは０．１〜０．７ｇ／ｍＬの範囲であり、さらに好ましくは０．１〜０．５ｇ／ｍＬの範囲である。 When the bulk density of the catalyst body is within the above range, the catalyst body moves, so that it is difficult to form a fixed short path, and it is possible to uniformly contact the carbon-containing compound. Therefore, the bulk density of the catalyst body is in the range of 0.1 to 1 g / mL. More preferably, it is the range of 0.1-0.7 g / mL, More preferably, it is the range of 0.1-0.5 g / mL.
かさ密度とは単位かさ体積あたりの粉体重量のことである。以下にかさ密度の測定方法を二つ示す。二つの測定方法の平均値をかさ密度とする。粉体のかさ密度は、測定時の温度、湿度に影響されることがある。ここで言うかさ密度は、温度２０±１０℃、湿度６０±１０％で測定したときの値である。メスシリンダーを測定容器として用いる。一つ目の測定方法は、予め定めた重量の触媒体を加える。かさ密度の測定に際しては５ｇ以上の触媒体を加えることが好ましい。その後、メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返した後、目視にて触媒体が占める容積値の変化率が４％以内であることを確認し、操作を終了する。もし容積値に目視にて４％以上の変化があれば、再度メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返し、目視にて触媒体が占める容積値に４％以上の変化がないことを確認して操作を終了する。上記の方法で詰めた触媒体の重量を触媒体が占める容積で割った値（＝重量（ｇ）／体積（ｍＬ））を触媒体のかさ密度とする。二つ目の測定方法は少量の触媒体を加え、メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返した後、再び少量の触媒体を加え、メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返す。この操作を触媒体が予め定めた容積を占めるまで繰り返す。容積は１０ｍＬ以上とすることが好ましい。上記の方法で詰めた触媒体の重量を触媒体が占める容積で割った値（＝重量（ｇ）／体積（ｍＬ））を触媒体のかさ密度とする。 Bulk density is the weight of powder per unit bulk volume. Two methods for measuring bulk density are shown below. The average value of the two measurement methods is the bulk density. The bulk density of the powder may be affected by the temperature and humidity at the time of measurement. The bulk density referred to here is a value measured at a temperature of 20 ± 10 ° C. and a humidity of 60 ± 10%. A graduated cylinder is used as a measuring container. In the first measurement method, a catalyst body having a predetermined weight is added. In measuring the bulk density, it is preferable to add 5 g or more of a catalyst body. Thereafter, dropping the bottom of the graduated cylinder from the height of 1 cm on the floor is repeated 20 times, and then it is visually confirmed that the rate of change of the volume value occupied by the catalyst body is within 4%, and the operation is finished. . If there is a visual change of 4% or more in the volume value, the bottom of the graduated cylinder is dropped again from the height of 1 cm on the floor 20 times, and the volume value occupied by the catalyst body is visually 4% or more. Confirm that there is no change and finish the operation. A value obtained by dividing the weight of the catalyst body packed by the above method by the volume occupied by the catalyst body (= weight (g) / volume (mL)) is defined as the bulk density of the catalyst body. The second measurement method is to add a small amount of catalyst body, drop the bottom of the graduated cylinder from the height of 1 cm on the floor 20 times, add a small amount of catalyst body again, and place the bottom of the graduated cylinder on the floor surface. Repeat the drop 20 times from the height of 1 cm. This operation is repeated until the catalyst body occupies a predetermined volume. The volume is preferably 10 mL or more. A value obtained by dividing the weight of the catalyst body packed by the above method by the volume occupied by the catalyst body (= weight (g) / volume (mL)) is defined as the bulk density of the catalyst body.
以下、実施例により本発明を具体的に説明するが、本発明はこれらの実施例のみに限定されるものではない。なお、各特性は以下の方法で測定した。
［触媒体の評価方法］
（粒径）
触媒体の粒径は、前記した篩い分け後の触媒体をサンプリングし、ＪＩＳ Ｚ ８８０１に準じた目開きの篩いに投入して求めた。すなわち、目開きの大きい篩いが上段になるように重ね、最上段の篩いに測定する触媒体を投入し、機械的に振動を与え、各々の篩いの上に残った粉末の量を測った。
（かさ密度の測定方法）
メスシリンダーを測定容器として用いた。一つ目の測定方法は、予め定めた重量の触媒体を加えた後、メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返した。目視にて触媒体が占める容積値の変化率が４％以内であれば、操作を終了するが、容積値が目視にて４％の変化があれば、再度メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返し、目視にて触媒体が占める容積値に４％以上の変化がないことを確認して操作を終了した。二つ目の測定方法は少量の触媒体を加え、メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返した後、再び少量の触媒体を加え、メスシリンダーの底を床面１ｃｍの高さから落とすことを２０回繰り返した。この操作を触媒体が予め定めた容積を占めるまで繰り返した。上記の方法で詰めた触媒体の重量を触媒体が占める容積で割った値（＝重量（ｇ）／体積（ｍＬ））を触媒体のかさ密度として、二つの測定方法の平均をとった。
［カーボンナノチューブの評価方法］
（熱重量分析によるカーボンナノチューブの純度評価）
約１ｍｇの試料を熱重量分析装置（島津製作所製 ＴＧＡ-６０）に設置し、空気中、１０℃／分の昇温速度にて室温から１０００℃まで昇温した。そのときの重量変化を測定し、重量減少曲線を時間で微分することにより微分熱重量曲線(ＤＴＧ)（ｘ軸を温度（℃）、ｙ軸をＤＴＧ（ｍｇ／ｍｉｎ））を得た。通常の精製をしたカーボンナノチューブ含有組成物はＤＴＧ曲線において高温側と低温側に二つの燃焼ピークが現れることが多い。本発明においては高温側の燃焼ピークは６００〜９００℃である。このピークのピーク面積に相当する範囲の重量減量分をＴＧ（Ｈ）とする。低温側の燃焼ピークとは３５０℃〜高温側の燃焼ピークへと変化する変曲点までにあり、このピークのピーク面積に相当する範囲の重量減量分をＴＧ（Ｌ）とする。なお、変曲点が存在しない場合には３５０℃〜６００℃の範囲の重量減量分をＴＧ（Ｌ）とする。ＴＧ（Ｌ）はアモルファスカーボンなどのカーボンナノチューブ以外の炭素不純物がカーボンナノチューブに付着したものと考えられる。炭素不純物の割合が大きいほどＴＧ（Ｌ）が大きくなり、カーボンナノチューブの割合が大きいほどＴＧ（Ｈ）が大きくなる。ＴＧ（Ｈ）を（ＴＧ（Ｈ）＋ＴＧ（Ｌ））で割ることでカーボンナノチューブ含有組成物の純度として表現することができる。
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples. Each characteristic was measured by the following method.
[Catalyst body evaluation method]
(Particle size)
The particle size of the catalyst body was determined by sampling the catalyst body after sieving and putting it in a sieve with openings according to JIS Z8801. That is, the sieves with large openings were stacked so as to be in the upper stage, the catalyst body to be measured was put into the uppermost sieve, mechanically vibrated, and the amount of powder remaining on each sieve was measured.
(Measurement method of bulk density)
A graduated cylinder was used as a measurement container. In the first measurement method, after adding a predetermined weight of the catalyst body, dropping the bottom of the graduated cylinder from the height of 1 cm of the floor surface was repeated 20 times. If the change rate of the volume value occupied by the catalyst body is visually within 4%, the operation is terminated, but if the volume value changes visually by 4%, the bottom of the graduated cylinder is again placed on the floor surface of 1 cm. Dropping from the height was repeated 20 times, and the operation was terminated after visually confirming that there was no change of 4% or more in the volume value occupied by the catalyst body. The second measurement method is to add a small amount of catalyst body, drop the bottom of the graduated cylinder from the height of 1 cm on the floor 20 times, add a small amount of catalyst body again, and place the bottom of the graduated cylinder on the floor. Dropping from a height of 1 cm was repeated 20 times. This operation was repeated until the catalyst body occupied a predetermined volume. The value obtained by dividing the weight of the catalyst body packed by the above method by the volume occupied by the catalyst body (= weight (g) / volume (mL)) was taken as the bulk density of the catalyst body, and the average of the two measurement methods was taken.
[Method for evaluating carbon nanotubes]
(Evaluation of carbon nanotube purity by thermogravimetric analysis)
About 1 mg of a sample was placed in a thermogravimetric analyzer (TGA-60 manufactured by Shimadzu Corporation), and the temperature was increased from room temperature to 1000 ° C. at a temperature increase rate of 10 ° C./min. The weight change at that time was measured, and the weight loss curve was differentiated by time to obtain a differential thermogravimetric curve (DTG) (temperature (° C.) on the x-axis and DTG (mg / min) on the y-axis). In general, a carbon nanotube-containing composition that has been refined often has two combustion peaks on the high temperature side and the low temperature side in the DTG curve. In the present invention, the combustion peak on the high temperature side is 600 to 900 ° C. The weight loss in a range corresponding to the peak area of this peak is defined as TG (H). The combustion peak on the low temperature side is from 350 ° C. to the inflection point at which the combustion peak changes to the combustion peak on the high temperature side, and the weight loss in the range corresponding to the peak area of this peak is TG (L). When there is no inflection point, the weight loss in the range of 350 ° C. to 600 ° C. is defined as TG (L). It is considered that TG (L) has carbon impurities other than carbon nanotubes such as amorphous carbon attached to the carbon nanotubes. The larger the proportion of carbon impurities, the larger TG (L), and the larger the proportion of carbon nanotubes, the larger TG (H). By dividing TG (H) by (TG (H) + TG (L)), it can be expressed as the purity of the carbon nanotube-containing composition.
［実施例１］
（触媒調製）
２４．６ｇのクエン酸鉄（ＩＩＩ）アンモニウム（和光純薬工業社製）をイオン交換水６．７ｋｇに溶解した。この溶液に、酸化マグネシウム（ＭｇＯ、岩谷社製 ＭＪ−３０）を１０００ｇ加え、撹拌機で６０分間激しく撹拌処理した後に、懸濁液を１０Ｌのオートクレーブ容器中に導入した。密閉した状態で撹拌しながら、２００℃に加熱し２時間保持した。その後オートクレーブ容器を放冷し、容器からスラリー状の白濁物質を取り出し、過剰の水分を吸引濾過により濾別し、１２０℃の乾燥機中で加熱乾燥した。得られた固形分は篩い上で、乳棒で細粒化しながら、０．８５〜１．７０ｍｍの範囲の粒径の触媒体を回収した。なお、篩いはアズワン（株）製５−３２９１シリーズを用いた。得られた顆粒状触媒体を電気炉中に導入し、大気下６００℃で３時間加熱した。得られた触媒体のかさ密度は０．３０７ｇ／ｍＬであった。
（カーボンナノチューブ含有組成物製造）
図１に示した装置を用いてカーボンナノチューブの合成を行った。反応器１０４は内径７５ｍｍ、長さは１１００ｍｍの円筒形石英管である。中央部に石英焼結板１０３を具備し、石英管下方部には、キャリアガスガスおよび原料ガス供給ラインである混合ガス導入管１０９、上部には廃ガス管１０７を具備する。さらに、反応管内の温度を検知するために温度計１０６を具備する。炭素含有化合物を予熱するための領域（予熱域）は１０２、予熱した炭素含有化合物とカーボンナノチューブ製造用触媒体を接触、反応させる領域（反応域）は１０１である。予熱域及び反応域は任意温度に保持できるように反応器の円周を取り囲む過熱器として電気炉を具備する。
[Example 1]
(Catalyst preparation)
24.6 g of iron (III) ammonium citrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 6.7 kg of ion exchange water. To this solution, 1000 g of magnesium oxide (MgO, MJ-30 manufactured by Iwatani Corporation) was added, and after vigorously stirring for 60 minutes with a stirrer, the suspension was introduced into a 10 L autoclave container. While stirring in a sealed state, it was heated to 200 ° C. and held for 2 hours. Thereafter, the autoclave container was allowed to cool, the slurry-like cloudy substance was taken out from the container, excess water was filtered off by suction filtration, and heat-dried in a 120 ° C. drier. The obtained solid content was refined with a pestle on a sieve, and a catalyst body having a particle size in the range of 0.85 to 1.70 mm was collected. The sieve used was 5-3291 series manufactured by ASONE. The obtained granular catalyst was introduced into an electric furnace and heated at 600 ° C. for 3 hours in the atmosphere. The bulk density of the obtained catalyst body was 0.307 g / mL.
(Production of carbon nanotube-containing composition)
Carbon nanotubes were synthesized using the apparatus shown in FIG. The
調製した固体触媒体１３２ｇをとり、鉛直方向に設置した反応器の中央部の石英焼結板上に導入することで触媒層１０５を形成した。予熱域温度の設定を９００℃、反応域温度の設定を８６０℃とし、触媒体層を加熱しながら、反応器底部から反応器上部方向へ向けてマスフローコントローラー１０８を用いて窒素ガスを１６．５Ｌ／ｍｉｎで供給し、触媒体層を通過するように流通させた。その後、窒素ガスを供給しながら、さらにマスフローコントローラー１０８を用いてメタンガスを０．７８Ｌ／ｍｉｎ（全ガス流量に対して４．５ｖｏｌ％）で６０分間導入して触媒体層を通過するように通気し、反応させた。メタンガスの導入を止め、窒素ガスを１６．５Ｌ／ｍｉｎ通気させながら、石英反応管を室温まで冷却した。加熱を停止させ室温まで放置し、室温になってから反応器から触媒体とカーボンナノチューブを含有するカーボンナノチューブ含有組成物を取り出した。
（精製工程：液相酸化処理＋アンモニア処理＋硝酸ドープ）
得られたカーボンナノチューブ含有組成物が付着した触媒担体を約１３０ｇ用いて４．８Ｎの塩酸水溶液２０００ｍＬ中で１時間撹拌することで触媒金属である鉄とその担体であるＭｇＯを溶解した。得られた黒色懸濁液はミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。濾取物は再度４．８Ｎの塩酸水溶液４００ｍＬに投入し脱ＭｇＯ処理をし、濾取した。この操作を２回繰り返した（脱ＭｇＯ処理）。その後、イオン交換水で濾取物の懸濁液が中性となるまで水洗後、水を含んだウェット状態のままカーボンナノチューブ組成物を得た。
A
(Purification process: liquid phase oxidation + ammonia treatment + nitric acid dope)
About 130 g of the obtained catalyst support having the carbon nanotube-containing composition adhered thereto was stirred in 2000 mL of a 4.8N hydrochloric acid aqueous solution for 1 hour to dissolve iron as the catalyst metal and MgO as the support. The resulting black suspension was subjected to suction filtration using a 90 mm inner diameter filter equipped with an Omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore. The filtered product was again poured into 400 mL of a 4.8N hydrochloric acid aqueous solution, treated with MgO, and collected by filtration. This operation was repeated twice (de-MgO treatment). Thereafter, the carbon nanotube composition was obtained in a wet state containing water after washing with ion-exchanged water until the suspension of the filtered material became neutral.
得られたウェット状態のカーボンナノチューブ含有組成物の乾燥重量分に対して、約３３３倍の重量の濃硝酸（キシダ化学 １級 Ａｓｓａｙ６０%）を添加した。その後、１４０℃±４℃に加熱したオイルバスで２４時間攪拌しながら加熱還流した。加熱還流後、室温まで放冷し、カーボンナノチューブ含有組成物を含む硝酸溶液をイオン交換水で２倍に希釈して、ミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。イオン交換水で濾取物の懸濁液が中性となるまで水洗後、水を含んだウェット状態のままカーボンナノチューブ組成物を得た。 About 333 times the weight of concentrated nitric acid (Kishida Chemical Grade 1 Assay 60%) was added to the dry weight of the obtained carbon nanotube-containing composition in the wet state. Then, it heated and refluxed, stirring for 24 hours with the oil bath heated at 140 degreeC +/- 4 degreeC. After heating under reflux, the inside diameter was allowed to cool to room temperature, and the nitric acid solution containing the carbon nanotube-containing composition was diluted 2 times with ion-exchanged water, and an Omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore was used. Suction filtration was performed using a 90 mm filter. After washing with ion-exchanged water until the suspension of the filtered material became neutral, a carbon nanotube composition was obtained in a wet state containing water.
得られたカーボンナノチューブ含有組成物の含むウェットケークを２８％アンモニア水溶液（キシダ化学 特級）０．３Ｌに添加し、室温下で１時間撹拌した。その後、該溶液をミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。その後メンブレンフィルター上のウェットケークが中性付近になるまでイオン交換水で洗浄し、水を含んだウェット状態のままカーボンナノチューブ組成物を得た。 The wet cake containing the obtained carbon nanotube-containing composition was added to 0.3 L of a 28% aqueous ammonia solution (Kishida Chemical Special Grade) and stirred at room temperature for 1 hour. Thereafter, the solution was subjected to suction filtration using a 90 mm inner diameter filter equipped with an omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore. Thereafter, the membrane was washed with ion-exchanged water until the wet cake on the membrane filter became near neutral, and a carbon nanotube composition was obtained in a wet state containing water.
得られたカーボンナノチューブ含有組成物を含むウェットケークを６０％硝酸水溶液（キシダ化学 １級 Ａｓｓａｙ６０%）３００ｍＬ中に添加した。室温で２４時間撹拌した後にミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。その後メンブレンフィルター上のウェットケークが中性付近になるまでイオン交換水で洗浄した。水を含んだウェット状態のままカーボンナノチューブ含有組成物を保存した。このカーボンナノチューブ含有濾取物の一部を採取し、１２０℃で加熱乾燥を一晩行い、乾燥前後の重量からウェット中のカーボンナノチューブ含有組成物の濃度を算出した。 The obtained wet cake containing the carbon nanotube-containing composition was added to 300 mL of a 60% nitric acid aqueous solution (Kishida Chemical 1st grade Assay 60%). After stirring for 24 hours at room temperature, the mixture was subjected to suction filtration using a 90 mm inner diameter filter equipped with an Omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore. Thereafter, the membrane was washed with ion-exchanged water until the wet cake on the membrane filter became near neutral. The carbon nanotube-containing composition was stored in a wet state containing water. A part of the carbon nanotube-containing filtered product was collected, dried by heating at 120 ° C. overnight, and the concentration of the carbon nanotube-containing composition in the wet was calculated from the weight before and after drying.
得られたウェット状態のカーボンナノチューブ含有組成物全体の重量にカーボンナノチューブ含有組成物濃度をかけて算出したカーボンナノチューブ含有組成物の乾燥重量（ＣＮＴ収量）（触媒体１００ｇ当たり）は０．２６４ｇであった。 The dry weight (CNT yield) (per 100 g of catalyst body) of the carbon nanotube-containing composition calculated by multiplying the weight of the obtained wet carbon nanotube-containing composition by the concentration of the carbon nanotube-containing composition was 0.264 g. It was.
熱重量分析を行った結果、カーボンナノチューブ含有組成物（カーボンナノチューブの純度）はＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．８９３であった。 As a result of thermogravimetric analysis, the composition containing carbon nanotubes (purity of carbon nanotubes) was TG (H) / (TG (L) + TG (H)) = 0.893.
［実施例２］
実施例１と同様の触媒調製操作を行った。触媒体のかさ密度は０．２７８ｇ／ｍＬであった。
[Example 2]
The same catalyst preparation operation as in Example 1 was performed. The bulk density of the catalyst body was 0.278 g / mL.
実施例１と同様のカーボンナノチューブ含有組成物製造装置・操作で上記触媒体を用いて行った。予熱域温度は９５０℃、反応域温度は８６０℃に設定した。 The same carbon nanotube-containing composition production apparatus / operation as in Example 1 was used and the catalyst body was used. The preheating zone temperature was set to 950 ° C, and the reaction zone temperature was set to 860 ° C.
実施例１と同様の精製処理を行った。最終的に得られた乾燥状態のカーボンナノチューブ含有組成物全体の重量は触媒体１００ｇ当たりで０．３７５ｇであった。 The same purification treatment as in Example 1 was performed. The weight of the finally obtained carbon nanotube-containing composition in a dry state was 0.375 g per 100 g of the catalyst body.
実施例１と同様に熱重量分析を行った結果、ＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．８９７であった。 As a result of performing thermogravimetric analysis in the same manner as in Example 1, it was TG (H) / (TG (L) + TG (H)) = 0.897.
［実施例３］
実施例１と同様の触媒調製操作を行った。触媒体のかさ密度は０．２８６ｇ／ｍＬであった。
[Example 3]
The same catalyst preparation operation as in Example 1 was performed. The bulk density of the catalyst body was 0.286 g / mL.
実施例１と同様のカーボンナノチューブ含有組成物製造装置・操作で上記触媒体の凝集体を用いて行った。予熱域温度は１０００℃、反応域温度は８６０℃に設定した。 The same carbon nanotube-containing composition production apparatus and operation as in Example 1 were used to perform the above-mentioned catalyst aggregates. The preheating zone temperature was set to 1000 ° C, and the reaction zone temperature was set to 860 ° C.
実施例１と同様の精製処理を行った。最終的に得られた乾燥状態のカーボンナノチューブ含有組成物全体の重量は触媒体１００ｇ当たりで０．３０３ｇであった。 The same purification treatment as in Example 1 was performed. The weight of the finally obtained carbon nanotube-containing composition in a dry state was 0.303 g per 100 g of the catalyst body.
実施例１と同様に熱重量分析を行った結果、ＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．８９３であった。 As a result of performing the thermogravimetric analysis in the same manner as in Example 1, TG (H) / (TG (L) + TG (H)) = 0.893.
［実施例４］
実施例１と同様の触媒調製操作を行った。触媒体のかさ密度は０．２７８ｇ／ｍＬであった。
[Example 4]
The same catalyst preparation operation as in Example 1 was performed. The bulk density of the catalyst body was 0.278 g / mL.
実施例１と同様のカーボンナノチューブ含有組成物製造装置・操作で上記触媒体の凝集体を用いて行った。予熱域温度は９００℃、反応域温度は９００℃に設定した。 The same carbon nanotube-containing composition production apparatus and operation as in Example 1 were used to perform the above-mentioned catalyst aggregates. The preheating zone temperature was set to 900 ° C, and the reaction zone temperature was set to 900 ° C.
実施例１と同様の精製処理を行った。最終的に得られた乾燥状態のカーボンナノチューブ含有組成物全体の重量は触媒体１００ｇ当たりで０．３０９ｇであった。 The same purification treatment as in Example 1 was performed. The total weight of the carbon nanotube-containing composition finally obtained was 0.309 g per 100 g of the catalyst body.
実施例１と同様に熱重量分析を行った結果、ＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．８９２であった。 As a result of performing thermogravimetric analysis in the same manner as in Example 1, it was TG (H) / (TG (L) + TG (H)) = 0.892.
［実施例５］
実施例１と同様の触媒調製操作を行った。触媒体のかさ密度は０．３０７ｇ／ｍＬであった。
[Example 5]
The same catalyst preparation operation as in Example 1 was performed. The bulk density of the catalyst body was 0.307 g / mL.
実施例１と同様のカーボンナノチューブ含有組成物製造装置・操作で上記触媒体の凝集体を用いて行った。予熱域温度は９５０℃、反応域温度は９００℃に設定した。 The same carbon nanotube-containing composition production apparatus and operation as in Example 1 were used to perform the above-mentioned catalyst aggregates. The preheating zone temperature was set to 950 ° C, and the reaction zone temperature was set to 900 ° C.
実施例１と同様の精製処理を行った。最終的に得られた乾燥状態のカーボンナノチューブ含有組成物全体の重量は触媒体１００ｇ当たりで０．２９４ｇであった。 The same purification treatment as in Example 1 was performed. The weight of the finally obtained carbon nanotube-containing composition in a dry state was 0.294 g per 100 g of the catalyst body.
実施例１と同様に熱重量分析を行った結果、ＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．８２０であった。 As a result of performing the thermogravimetric analysis in the same manner as in Example 1, it was TG (H) / (TG (L) + TG (H)) = 0.820.
［実施例６］
実施例１と同様の触媒調製操作を行った。触媒体のかさ密度は０．２４８ｇ／ｍＬであった。
[Example 6]
The same catalyst preparation operation as in Example 1 was performed. The bulk density of the catalyst body was 0.248 g / mL.
実施例１と同様のカーボンナノチューブ含有組成物製造装置・操作で上記触媒体の凝集体を用いて行った。予熱域温度は１０００℃、反応域温度は９００℃に設定した。 The same carbon nanotube-containing composition production apparatus and operation as in Example 1 were used to perform the above-mentioned catalyst aggregates. The preheating zone temperature was set to 1000 ° C, and the reaction zone temperature was set to 900 ° C.
実施例１と同様の精製処理を行った。最終的に得られた乾燥状態のカーボンナノチューブ含有組成物全体の重量は触媒体１００ｇ当たりで０．３１４ｇであった。 The same purification treatment as in Example 1 was performed. The total weight of the carbon nanotube-containing composition finally obtained was 0.314 g per 100 g of the catalyst body.
実施例１と同様に熱重量分析を行った結果、ＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．８８５であった。 The thermogravimetric analysis was performed in the same manner as in Example 1. As a result, TG (H) / (TG (L) + TG (H)) = 0.85.
［比較例１］
（触媒調製）
２４．６ｇのクエン酸鉄（ＩＩＩ）アンモニウム（和光純薬工業社製）をイオン交換水６．７ｋｇに溶解した。この溶液に、酸化マグネシウム（ＭｇＯ、岩谷社製 ＭＪ−３０）を約１０００ｇ加え、撹拌機で６０分間激しく撹拌処理した後に、懸濁液を１０Ｌのオートクレーブ容器中に導入した。密閉した状態で撹拌しながら、２００℃に加熱し２時間保持した。その後オートクレーブ容器を放冷し、容器からスラリー状の白濁物質を取り出し、過剰の水分を吸引濾過により濾別し、１２０℃の乾燥機中で加熱乾燥した。得られた固形分は篩い上で、乳棒で細粒化しながら、０．８５〜１．７０ｍｍの範囲の粒径の触媒体を回収した。なお、篩いはアズワン（株）製５−３２９１シリーズを用いた。得られた顆粒状触媒体を電気炉中に導入し、大気下６００℃で３時間加熱した。得られた触媒体のかさ密度は０．３０７ｇ／ｍＬであった。
（カーボンナノチューブ含有組成物製造）
図１に示した装置を用いてカーボンナノチューブの合成を行った。反応器１０４は内径７５ｍｍ、長さは１１００ｍｍの円筒形石英管である。中央部に石英焼結板１０３を具備し、石英管下方部には、キャリアガスガスおよび原料ガス供給ラインである混合ガス導入管１０９、上部には廃ガス管１０７を具備する。さらに、反応管内の温度を検知するために温度計１０６を具備する。炭素含有化合物を予熱するための領域（予熱域）は１０２、予熱した炭素含有化合物とカーボンナノチューブ製造用触媒体を接触、反応させる領域（反応域）は１０１である。予熱域及び反応域は任意温度に保持できるように反応器の円周を取り囲む過熱器として電気炉を具備する。
[Comparative Example 1]
(Catalyst preparation)
24.6 g of iron (III) ammonium citrate (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 6.7 kg of ion exchange water. About 1000 g of magnesium oxide (MgO, MJ-30 manufactured by Iwatani Corporation) was added to this solution, and after vigorously stirring for 60 minutes with a stirrer, the suspension was introduced into a 10 L autoclave container. While stirring in a sealed state, it was heated to 200 ° C. and held for 2 hours. Thereafter, the autoclave container was allowed to cool, the slurry-like cloudy substance was taken out from the container, excess water was filtered off by suction filtration, and heat-dried in a 120 ° C. drier. The obtained solid content was refined with a pestle on a sieve, and a catalyst body having a particle size in the range of 0.85 to 1.70 mm was collected. The sieve used was 5-3291 series manufactured by ASONE. The obtained granular catalyst was introduced into an electric furnace and heated at 600 ° C. for 3 hours in the atmosphere. The bulk density of the obtained catalyst body was 0.307 g / mL.
(Production of carbon nanotube-containing composition)
Carbon nanotubes were synthesized using the apparatus shown in FIG. The
調製した固体触媒体１３２ｇをとり、鉛直方向に設置した反応器の中央部の石英焼結板上に導入することで触媒層１０５を形成した。予熱域温度の設定を８００℃、反応域温度の設定を８６０℃とし、触媒体層を加熱しながら、反応器底部から反応器上部方向へ向けてマスフローコントローラー１０８を用いて窒素ガスを１６．５Ｌ／ｍｉｎで供給し、触媒体層を通過するように流通させた。その後、窒素ガスを供給しながら、さらにマスフローコントローラー１０８を用いてメタンガスを０．７８Ｌ／ｍｉｎ（全ガス流量に対して４．５ｖｏｌ％）で６０分間導入して触媒体層を通過するように通気し、反応させた。メタンガスの導入を止め、窒素ガスを１６．５Ｌ／ｍｉｎ通気させながら、石英反応管を室温まで冷却した。加熱を停止させ室温まで放置し、室温になってから反応器から触媒体とカーボンナノチューブを含有するカーボンナノチューブ含有組成物を取り出した。
（精製工程：液相酸化処理＋アンモニア処理＋硝酸ドープ）
得られたカーボンナノチューブ含有組成物が付着した触媒担体を約１３０ｇ用いて４．８Ｎの塩酸水溶液２０００ｍＬ中で１時間撹拌することで触媒金属である鉄とその担体であるＭｇＯを溶解した。得られた黒色懸濁液はミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。濾取物は再度４．８Ｎの塩酸水溶液４００ｍＬに投入し脱ＭｇＯ処理をし、濾取した。この操作を２回繰り返した（脱ＭｇＯ処理）。その後、イオン交換水で濾取物の懸濁液が中性となるまで水洗後、水を含んだウェット状態のままカーボンナノチューブ組成物を得た。
A
(Purification process: liquid phase oxidation + ammonia treatment + nitric acid dope)
About 130 g of the obtained catalyst support having the carbon nanotube-containing composition adhered thereto was stirred in 2000 mL of a 4.8N hydrochloric acid aqueous solution for 1 hour to dissolve iron as the catalyst metal and MgO as the support. The resulting black suspension was subjected to suction filtration using a 90 mm inner diameter filter equipped with an Omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore. The filtered product was again poured into 400 mL of a 4.8N hydrochloric acid aqueous solution, treated with MgO, and collected by filtration. This operation was repeated twice (de-MgO treatment). Thereafter, the carbon nanotube composition was obtained in a wet state containing water after washing with ion-exchanged water until the suspension of the filtered material became neutral.
得られたウェット状態のカーボンナノチューブ含有組成物の乾燥重量分に対して、約３３３倍の重量の濃硝酸（キシダ化学 １級 Ａｓｓａｙ６０%）を添加した。その後、１４０℃±４℃に加熱したオイルバスで約２４時間攪拌しながら加熱還流した。加熱還流後、室温まで放冷し、カーボンナノチューブ含有組成物を含む硝酸溶液をイオン交換水で２倍に希釈して、ミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。イオン交換水で濾取物の懸濁液が中性となるまで水洗後、水を含んだウェット状態のままカーボンナノチューブ含有組成物を得た。 About 333 times the weight of concentrated nitric acid (Kishida Chemical Grade 1 Assay 60%) was added to the dry weight of the obtained carbon nanotube-containing composition in the wet state. Thereafter, the mixture was heated to reflux with stirring in an oil bath heated to 140 ° C. ± 4 ° C. for about 24 hours. After heating under reflux, the inside diameter was allowed to cool to room temperature, and the nitric acid solution containing the carbon nanotube-containing composition was diluted 2 times with ion-exchanged water, and an Omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore was used. Suction filtration was performed using a 90 mm filter. After washing with ion-exchanged water until the suspension of the filtered material became neutral, a carbon nanotube-containing composition was obtained in a wet state containing water.
得られたカーボンナノチューブ含有組成物の含むウェットケークを２８％アンモニア水溶液（キシダ化学 特級）３００ｍＬに添加し、室温下で１時間撹拌した。その後、該溶液をミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。その後メンブレンフィルター上のウェットケークが中性付近になるまでイオン交換水で洗浄し、水を含んだウェット状態のままカーボンナノチューブ含有組成物を得た。 The wet cake containing the obtained carbon nanotube-containing composition was added to 300 mL of a 28% aqueous ammonia solution (Kishida Chemical Special Grade) and stirred at room temperature for 1 hour. Thereafter, the solution was subjected to suction filtration using a 90 mm inner diameter filter equipped with an omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore. Thereafter, the membrane was washed with ion-exchanged water until the wet cake on the membrane filter became near neutral, and a carbon nanotube-containing composition was obtained in a wet state containing water.
得られたカーボンナノチューブ含有組成物を含むウェットケークを６０％硝酸水溶液（キシダ化学 １級 Ａｓｓａｙ６０%）０．３Ｌ中に添加した。室温で２４時間撹拌した後にミリポア社製オムニポアメンブレンフィルター（フィルタータイプ：１．０μｍＪＡ）をしいた内径９０ｍｍ濾過器を用いて吸引濾過した。その後メンブレンフィルター上のウェットケークが中性付近になるまでイオン交換水で洗浄した。水を含んだウェット状態のままカーボンナノチューブ含有組成物を保存した。このカーボンナノチューブ含有濾取物の一部を採取し、１２０℃で加熱乾燥を一晩行い、乾燥前後の重量からウェット中のカーボンナノチューブ含有組成物の濃度を算出した。 The obtained wet cake containing the carbon nanotube-containing composition was added to 0.3 L of a 60% nitric acid aqueous solution (Kishida Chemical 1st grade Assay 60%). After stirring for 24 hours at room temperature, the mixture was subjected to suction filtration using a 90 mm inner diameter filter equipped with an Omnipore membrane filter (filter type: 1.0 μm JA) manufactured by Millipore. Thereafter, the membrane was washed with ion-exchanged water until the wet cake on the membrane filter became near neutral. The carbon nanotube-containing composition was stored in a wet state containing water. A part of the carbon nanotube-containing filtered product was collected, dried by heating at 120 ° C. overnight, and the concentration of the carbon nanotube-containing composition in the wet was calculated from the weight before and after drying.
得られたウェット状態のカーボンナノチューブ含有組成物全体の重量にカーボンナノチューブ含有組成物濃度をかけて算出したカーボンナノチューブ含有組成物の乾燥重量（触媒体１００ｇ当たり）は０．２０５ｇであった。 The dry weight (per 100 g of catalyst body) of the carbon nanotube-containing composition calculated by multiplying the total weight of the obtained carbon nanotube-containing composition in the wet state by the concentration of the carbon nanotube-containing composition was 0.205 g.
熱重量分析を行った結果、カーボンナノチューブ含有組成物（カーボンナノチューブの純度）はＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．７６３であった。 As a result of performing thermogravimetric analysis, the composition containing carbon nanotubes (purity of carbon nanotubes) was TG (H) / (TG (L) + TG (H)) = 0.663.
［比較例２］
比較例１と同様の触媒調製操作を行った。触媒体のかさ密度は０．３０６ｇ／ｍＬであった。
[Comparative Example 2]
The same catalyst preparation operation as in Comparative Example 1 was performed. The bulk density of the catalyst body was 0.306 g / mL.
比較例１と同様のカーボンナノチューブ含有組成物製造装置・操作で上記触媒体を用いて行った。予熱域温度は９００℃、反応域温度は９５０℃に設定した。 The same carbon nanotube-containing composition production apparatus / operation as in Comparative Example 1 was used and the above catalyst body was used. The preheating zone temperature was set to 900 ° C, and the reaction zone temperature was set to 950 ° C.
比較例１と同様の精製処理を行った。最終的に得られた乾燥状態のカーボンナノチューブ含有組成物全体の重量は触媒体１００ｇ当たりで０．２１３ｇであった。 The same purification treatment as in Comparative Example 1 was performed. The weight of the finally obtained carbon nanotube-containing composition in a dry state was 0.213 g per 100 g of the catalyst body.
比較例１と同様に熱重量分析を行った結果、ＴＧ（Ｈ）／（ＴＧ（Ｌ）＋ＴＧ（Ｈ））＝０．７４１であった。 As a result of performing thermogravimetric analysis in the same manner as in Comparative Example 1, it was TG (H) / (TG (L) + TG (H)) = 0.711.
本発明によるカーボンナノチューブの製造方法は、品質の高いカーボンナノチューブを高収量で作成できるので、カーボンナノチューブの製造分野に有効に利用できる。 The method for producing carbon nanotubes according to the present invention can produce high-quality carbon nanotubes with high yield, and can be effectively used in the field of carbon nanotube production.
１０１ 反応域
１０２ 予熱域
１０３ 石英焼結板
１０４ 反応器
１０５ 触媒体層
１０６ 温度計
１０７ 排ガス管
１０８ マスフローコントローラー
１０９ 混合ガス導入管
DESCRIPTION OF
Claims (6)
6. The carbon nanotube-containing composition according to claim 1, wherein the metal catalyst contained in the catalyst body for producing carbon nanotubes is at least one selected from Group 8-10 transition metals. Production method.
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