JP2002338220A - Carbon composite including iron compound and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain carbonaceous composite material including iron carbide or iron and to provide a method for producing the material in a high yield. SOLUTION: The carbonaceous composite material containing an iron-carbon composite with iron carbide or iron filled into 10-90% of the internal spaces of nano-flake carbon tubes or multilayer carbon nanotubes having a nested structure is produced as follows; (1) pressure is regulated to 10<-5> Pa to 200 kPa in an inert gaseous atmosphere, the concentration of oxygen in a reactor is regulated in such a way that the ratio B/A of the amount B (Ncc) of oxygen to the volume A (liter) of the reactor ranges from 1×10<-10> to 1×10<-1> and an iron halide is heated to 600-900 deg.C in the reactor and (2) the reactor is filled with an inert gaseous atmosphere, pressure is regulated to 10<-5> Pa to 200 kPa, a thermally decomposable carbon source is introduced and heat treatment is carried out at 600-900 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an iron-carbon composite containing an iron compound such as iron carbide or iron, a carbonaceous material containing the iron-carbon composite, and a method for producing the same.

[0002]

2. Description of the Related Art A carbon nanotube is a hollow carbon material in which a graphite sheet (ie, a carbon atom surface of a graphite structure or a graphene sheet) is closed in a tubular shape, the diameter is on a nanometer scale, and the wall structure is a graphite structure. have. Such carbon nanotubes are available in 1991
Discovered by Sumio Iijima in 1965. Among carbon nanotubes, those with a wall structure closed in a tube shape with a single graphite sheet are called single-walled carbon nanotubes, and those with multiple graphite sheets closed in a tube shape and nested are It is called a nested multi-walled carbon nanotube.

[0003] In addition, it has been reported that the graphite wall structure has a scroll-like structure, which is similar to a normal nested multi-walled carbon nanotube but has a different wall structure made of carbon.

[0004] In recent years, in order to improve the electrical and magnetic characteristics of conductors, electron emitters, and the like, metal such as carbon nanotubes (hereinafter sometimes referred to as “CNTs”) has been placed in a hollow portion surrounded by a tube wall. Attempts have been made to include them.

[0005] For example, Japanese Patent No. 2546114 describes a foreign substance-containing carbon nanotube in which a substance other than carbon, such as metal, is contained in a hollow hole at the center of a nested multi-walled carbon nanotube. The foreign substance-encapsulated carbon nanotube is formed by simultaneously removing or removing the tip of the nested multi-walled carbon nanotube closed in a cap shape once or after removing the cap, and then depositing a substance other than carbon on the tip of the carbon nanotube, and thermally diffusing the carbon nanotube. From the tip of the tube into a hollow hole in the center of the tube.

[0006] Japanese Patent Application Laid-Open No. 9-142819 discloses a carbon tube having a diameter of 10 nm to 1 μm and a length of 1 to 100 μm containing a foreign substance. This foreign substance-encapsulated carbon tube is formed by using an inorganic substance having substantially linear pores as a mold, and carbonizing the organic substance coated on the pore inner walls by heating, or forming a gas in the pores. Once the carbon tube is once produced by carbonizing the hydrocarbon in the gas phase and depositing the carbon thin film, a foreign substance is brought into contact with the tube in a solution state or a molten state, and the carbon tube is formed into a hollow portion of the carbon tube. It is manufactured by inserting a foreign substance (an inorganic substance is dissolved and removed before or after insertion).

Further, Japanese Patent Application Laid-Open No. 2000-204471 discloses that
The diameter is 1 to 100 nm, and the ratio between the diameter and the major axis length is 50.
A thin metal wire made of the above thin wire material, particularly a thin metal wire covered with a carbon tube is described. The method for producing the thin metal wire covered with the carbon tube is the same as the production method described in JP-A-9-142819, and a cylindrical inner wall of an inorganic substance having substantially linear pores is provided. It is manufactured by a manufacturing method comprising a first step of forming carbon and a second step of depositing a metal inside the tubular carbon.

[0008]

However, the above conventional method requires at least two steps of forming a carbon tube and then inserting a foreign substance.
The management and control of each process are complicated and the productivity is low.
Further, Japanese Unexamined Patent Application Publication Nos. 9-142819 and 2000
In the production method described in -204471, a step of dissolving and removing the inorganic substance used as the mold is required.

Conventionally, a complex in which a metal, particularly iron or an iron compound is sealed in a space surrounded by a wall made of carbon of a tubular carbon material such as a carbon nanotube in a carbon tube, is prepared on a mg scale or more. No way to get it has been developed. Therefore, at present, there is no specific practical research on a carbon-metal composite in which a metal or the like is included in a hollow portion of a tubular carbon material.

The present invention provides a composite in which iron or an iron compound is encapsulated in a substantial part of a space surrounded by a carbon tube, a carbonaceous material containing such a composite, and a method for producing the same. Main purpose.

[0011]

Means for Solving the Problems The present inventor has made the following studies in view of the above-mentioned current state of the art, and has found the following.

(1) In an inert gas atmosphere, the pressure is 10 ^-5
Pa to 200 kPa, and adjust the oxygen concentration in the reactor,
When the reaction furnace volume is A (liter) and the oxygen amount is B (Ncc), the ratio B / A is adjusted to a concentration of 1 × 10 ^-10 to 1 × 10 ^-1, and halogenation is performed in the reaction furnace. 600-9 iron
Heating to 00 ° C, (2) setting the inside of the reaction furnace to an inert gas atmosphere, adjusting the pressure to 10 ⁻⁵ Pa to 200 kPa, introducing a pyrolytic carbon source, and performing heat treatment at 600 to 900 ° C. Thereby, a carbon material including a tube made of carbon and an iron-carbon composite made of iron or iron carbide contained in the space inside the tube can be manufactured at a stroke.

In the cooling step after the step (2),
By controlling the cooling rate to a specific range, the carbon tube obtained is considered to be composed of a plurality (usually many) of flake-like graphite sheets gathered in a patchwork or papier shape. , A carbon tube made of an aggregate of graphite sheets. In the present specification, this carbon tube is referred to as a “nanoflake carbon tube”.
That. This nanoflake carbon tube is a single-walled carbon nanotube in which one 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 cylinders or nests. It is a tubular carbon material with a completely different structure.

[0014] The space inside the tube of the nanoflake carbon tube (ie, the space surrounded by the tube wall of the nanoflake carbon tube) forms a considerable portion of the space, particularly 10 to 90% of the space. Filled with iron or iron to form an iron-carbon composite.

Further, as a post-step of the above-mentioned step (2), by performing a heat treatment in an inert gas and cooling at a specific cooling rate, a tube made of carbon obtained is a multi-walled carbon nanotube having a nested structure. Become. In the space in the tube of the multi-walled carbon nanotube, a considerable part of the space, particularly 10 to 90% of the space, is filled with iron carbide or iron to form an iron-carbon composite.

The present invention has been completed by further study based on these findings, and provides the following iron-carbon composite and a method for producing the same.

Item 1 An iron-carbon composite comprising (a) a carbon tube selected from the group consisting of a nanoflake carbon tube and a nested multi-walled carbon nanotube, and (b) iron carbide or iron, wherein An iron-carbon composite, wherein 10 to 90% of the space is filled with iron carbide or iron.

Item 2 is linear and has an outer diameter of 1 to 100 n.
m, the thickness of the wall portion made of carbon is 49 nm or less, is substantially uniform over the entire length, and the aspect ratio L / D when the length is L and the outer diameter is D is 5 to 5. 1000
Item 2. The iron-carbon composite according to Item 1, which is 0.

Item 3. The above-mentioned item 1, wherein the average distance (d002) between the carbon mesh planes is 0.34 nm or less, when the wall of the carbon tube constituting the iron-carbon composite is measured by an X-ray diffraction method. Or the iron-carbon composite according to 2.

Item 4 The iron-carbon composite according to any one of Items 1 to 3, wherein the carbon tube constituting the iron-carbon composite is a nanoflake carbon tube.

Item 5 The iron-carbon composite according to any one of Items 1 to 3, wherein the carbon tube constituting the iron-carbon composite is a nested multi-walled carbon nanotube.

Item 6: (a) A carbon tube selected from the group consisting of a nanoflake carbon tube and a nested multi-walled carbon nanotube, and (b) iron carbide or iron, which accounts for 10 to 90% of the space in the carbon tube. A carbonaceous material comprising iron carbide or an iron-carbon composite filled with iron.

Item 7 25 mm per 1 mg of carbonaceous material
^In the powder X-ray diffraction measurement of irradiating CuKα X-rays with an irradiation area of ² or more, the strongest integral among peaks at 40 ° <2θ <50 ° attributed to iron or iron carbide contained in the carbon tube. When the integrated intensity of the peak indicating the intensity is defined as Ia, and the integrated intensity of the peak at 26 ° <2θ <27 ° attributed to the average distance (d002) between the carbon net surfaces of the carbon tube is defined as Ib, Ia / Ib Is the ratio R
Item 7. The carbonaceous material according to Item 6, which has a particle size of 0.35 to 5.

Item 8: The iron-carbon composite is linear,
The outer diameter is 1 to 100 nm, the thickness of the carbon wall is 49 nm or less and is substantially uniform over the entire length, and the aspect ratio L when the length is L and the outer diameter is D
Item 8. The carbonaceous material according to item 6 or 7, wherein / D is 5 to 10,000.

Item 9. The above-mentioned item 6, wherein the average distance (d002) between carbon mesh planes is 0.34 nm or less when the wall of the carbon tube constituting the iron-carbon composite is measured by X-ray diffraction. 9. The carbonaceous material according to any one of items 1 to 8.

Item 10. The carbonaceous material according to any one of Items 6 to 9, wherein the carbon tube constituting the iron-carbon composite is a nanoflake carbon tube.

Item 11. The carbonaceous material according to any one of Items 6 to 9, wherein the carbon tube constituting the iron-carbon composite is a multi-walled carbon nanotube having a nested structure.

Item 12: (a) A carbon tube selected from the group consisting of a nanoflake carbon tube and a nested multi-walled carbon nanotube, and (b) iron carbide or iron, which accounts for 10 to 90% of the space in the carbon tube. A method for producing a carbonaceous material comprising an iron-carbon composite filled with iron carbide or iron, comprising the steps of: (1) adjusting the pressure to 10 ⁻⁵ Pa to 200 kPa in an inert gas atmosphere; The ratio B / A when the oxygen concentration of the reaction furnace is A (liter) and the oxygen amount is B (Ncc) is 1 × 10 ⁻¹⁰ to
Adjusting the concentration to 1 × 10 ⁻¹ and heating the iron halide to 600 to 900 ° C. in the reaction furnace; and (2) setting the pressure in the reaction furnace to 10 ⁻⁵ Pa with an inert gas atmosphere.
To 200 kPa, and introduced a pyrolytic carbon source.
A production method comprising a step of performing a heat treatment at 00 to 900 ° C.

Item 13 After the heat treatment step of the step (2), 50
By cooling to 500 ° C. at ２０００2000 ° C./h, a carbonaceous material containing an iron-carbon composite comprising iron carbide or iron filled in a nanoflake carbon tube and 10 to 90% of the space in the tube is removed. Item 12 to be generated
The production method described in 1.

Item 14 After the heat treatment step of the step (2), (3) a step of replacing the inside of the reaction furnace with an inert gas while maintaining the temperature of the step (2), and (4) a step of replacing the inside of the reaction furnace with the inert gas. 9 inside the reactor
A step of raising the temperature to 50 to 1500 ° C., (5) a step of maintaining the end point temperature at the temperature raising end point until a nested multi-walled carbon nanotube is generated, and (6) a rate of 50 ° C./h or less in the reaction furnace. By performing the cooling step, the nested multi-walled carbon nanotubes and the 10
Item 13. The production method according to the above item 12, wherein a carbonaceous material containing an iron-carbon composite comprising iron carbide or iron filled to 90% is produced.

Item 15. The method according to Item 12, wherein the heat treatment in the step (2) is performed in the presence of an organic iron complex.

Item 16. The method according to Item 15, wherein the organic iron complex is a ferrocene or iron carbonyl complex.

Item 17. The method according to any one of Items 12 to 16, wherein the iron halide is an iron chloride.

Item 18. The iron chloride is composed of FeCl ₂ , FeCl ₃ , Fe
The method according to Cl ₂ · 4H ₂ O and the term 17 is at least one selected from the group consisting of FeCl ₃ · 6H ₂ O.

Item 19: The pyrolytic carbon source has a carbon number of 6 to 1
The above items 12 to 18, which are at least one member selected from the group consisting of aromatic hydrocarbons having 2 carbon atoms, saturated aliphatic hydrocarbons having 1 to 10 carbon atoms, and unsaturated aliphatic hydrocarbons having 2 to 5 carbon atoms.
The production method according to any one of the above.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Iron-Carbon Composite of the Present Invention An iron-carbon composite according to the present invention comprises: (a) a carbon tube selected from the group consisting of nanoflake carbon tubes and nested multi-wall carbon nanotubes; ) Iron carbide or iron, and the space inside the carbon tube (that is, the space surrounded by the tube wall) is not substantially filled, but a part of the space, More specifically, about 10 to 90%, particularly about 30 to 80%, preferably about 40 to 70% is filled with iron carbide or iron.

In the iron-carbon composite of the present invention, the carbon portion is converted into a nanoflake carbon tube by cooling at a specific rate after the production steps (1) and (2), and the production steps (1) and (2) After performing (2), heat treatment is performed in an inert gas, and cooling is performed at a specific cooling rate, thereby obtaining a nested multi-walled carbon nanotube.

<(A-1) Nanoflake Carbon Tube> The iron-carbon composite comprising the nanoflake carbon tube and iron carbide or iron of the present invention is typically in the form of a column. FIG. 7 shows a transmission electron microscope (TEM) photograph of a cross section of the iron-carbon composite (obtained in Example 1) crossing the longitudinal direction, and FIG. 3 shows a TEM photograph of the side surface.

FIG. 10 (a-1) shows a schematic view of a TEM image of such a cylindrical nanoflake carbon tube. In (a-1) of FIG. 10, 100 schematically shows a TEM image in the longitudinal direction of the nanoflake carbon tube, and 200 shows a TEM image of a cross section almost perpendicular to the longitudinal direction of the nanoflake carbon tube. This is schematically shown.

The nanoflake carbon tube constituting the iron-carbon composite of the present invention is shown in FIG. 7 and FIG.
As is clear from 200 of 1), when a cross section crossing the longitudinal direction is observed by TEM, a large number of arc-shaped graphene sheet images are aggregated in a multilayer tube shape. , 214, a completely closed continuous ring is not formed, but a discontinuous ring interrupted on the way is formed. Some graphene sheet images may be branched, as shown at 211. At a discontinuous point, a plurality of arc-shaped TEM images constituting one discontinuous ring may have a partially disordered layer structure, as shown at 222 in FIG. 10A. 223
In some cases, there is a gap between adjacent graphene sheet images as shown in Fig. 5, but a large number of arc-shaped graphene sheet images observed by TEM form a multilayer tube structure as a whole .

Further, as is apparent from 100 in FIGS. 3 and 10 (a-1), when the longitudinal direction of the nanoflake carbon tube was observed by TEM, a large number of substantially linear graphene sheet images were obtained according to the present invention. The graphene sheet images 110 are not continuous over the entire length of the iron-carbon composite in the longitudinal direction, but are discontinuous on the way. It has become. Some graphene sheet images may be branched, as indicated by 111 in FIG. 1 (a-1). At the discontinuous point, among the TEM images arranged in layers, the TEM image of one discontinuous layer at least partially overlaps with the adjacent graphene sheet image as shown at 112 in (a-1) of FIG. In some cases, the TEM images may overlap with each other, and in some cases, they may be slightly separated from the adjacent graphene sheet images, as shown at 113. However, a large number of substantially linear TEM images form a multilayer structure as a whole.

The structure of the nanoflake carbon tube of the present invention is significantly different from the conventional multi-wall carbon nanotube. That is, as shown by 400 in FIG. 10A-2, the nested multi-walled carbon nanotube has a TEM image of a cross section perpendicular to the longitudinal direction, as shown by 410, a perfect circular TEM image. And a structure in which linear graphene sheet images 310 and the like continuous over the entire length in the longitudinal direction are arranged in parallel, as shown at 300 in FIG. 10 (a-2). (Concentric cylindrical or nested structure).

As described above, although the details have not been completely elucidated yet, the nanoflake carbon tube constituting the iron-carbon composite of the present invention has a large number of flake-like graphene sheets overlapping in a patchwork or papier shape. All seem to form a tube.

The nano-flake carbon tube of the present invention and the iron-carbon composite comprising iron carbide or iron contained in the space inside the tube are disclosed in Japanese Patent No. 2546114.
The structure of the carbon tube differs greatly from the composite in which metal is included in the space inside the tube of the nested multi-walled carbon nanotube as described in Material.

When the nano-flake carbon tube constituting the iron-carbon composite of the present invention was observed by TEM, a large number of substantially linear graphene sheet images oriented in the longitudinal direction were examined. The length of the image is usually about 2 to 500 nm, especially about 10 to 100 nm. That is, as shown by 100 in FIG. 10A, the substantially linear graphene sheet shown by 110
A large number of TEM images form a TEM image of the wall of the nanoflake carbon tube, and the length of each substantially linear graphene sheet image is usually about 2 to 500 nm, particularly about 10 to 100 nm. .

The carbon portion of the wall of the nanoflake carbon tube constituting the iron-carbon composite of the present invention has a tubular shape as a whole with a large number of flake-like graphene sheets oriented in the longitudinal direction as described above. However, when measured by the X-ray diffraction method, the average distance (d00
2) has a graphite structure of 0.34 nm or less.

The thickness of the wall of the iron-carbon composite nanoflake carbon tube of the present invention is 49 nm.
Hereinafter, especially about 0.1 to 20 nm, preferably 1 to 10
nm and is substantially uniform over the entire length.

<(A-2) Nested Multi-Walled Carbon Nanotube> As described above, the iron-carbon composite obtained by performing the steps (1) and (2) and then performing a specific heating step is obtained. Is a multi-walled carbon nanotube having a nested structure.

The nested multi-walled carbon nanotube obtained in this way is a concentric tube whose TEM image of a cross section perpendicular to the longitudinal direction forms a complete circle, as shown by 400 in FIG. And a structure in which continuous graphene sheet images are arranged in parallel over the entire length in the longitudinal direction (concentric cylindrical or nested structure)
It is.

The carbon part of the wall of the nested multi-walled carbon nanotube constituting the iron-carbon composite of the present invention is as follows:
It has a graphitic structure with an average distance (d002) between carbon nettings of 0.34 nm or less as measured by X-ray diffraction.

The thickness of the wall portion composed of the nested multi-walled carbon nanotube of the iron-carbon composite of the present invention is as follows:
It is 49 nm or less, particularly about 0.1 to 20 nm, preferably about 1 to 10 nm, and is substantially uniform over the entire length.

<(B) Encapsulated Iron Carbide or Iron> In the present specification, the filling rate (10 to 90%) of the space inside the carbon tube with iron carbide or iron is determined by the iron content obtained by the present invention. Observing the carbon composite with a transmission electron microscope,
It is the ratio of the area of the image of the portion filled with iron carbide or iron 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).

The filling form of iron carbide or iron includes a form in which the space in the carbon tube is continuously filled, a form in which the space in the carbon tube is intermittently filled, and the like. Filled intermittently. Therefore, the iron-carbon composite of the present invention can be called a metal-containing carbon composite, an iron compound-containing carbon composite, iron carbide, or an iron-containing carbon composite.

The iron carbide or iron included in the iron-carbon composite of the present invention is oriented in the longitudinal direction of the carbon tube, has high crystallinity, and is filled with iron carbide or iron. Ratio of the area of the TEM image of crystalline iron carbide or iron to the area of the TEM image of
Is generally about 90 to 100%, particularly 95 to 100%
It is about.

The high crystallinity of the encapsulated iron carbide or iron is attributed to the fact that the TEM images of the inclusions are arranged in a lattice when observed by TEM from the side of the iron-carbon composite of the present invention. It is clear from the fact that a clear diffraction pattern can be obtained from electron beam diffraction.

The inclusion of iron carbide or iron in the iron-carbon composite of the present invention can be easily confirmed by an electron microscope and an EDX (energy dispersive X-ray detector).

<Overall Shape of Iron-Carbon Composite> The iron-carbon composite of the present invention has a small curvature, is linear, and has a substantially uniform thickness throughout its entire length. Therefore, it has a uniform shape over the entire length. Its shape is columnar, mainly cylindrical.

The outer diameter of the iron-carbon composite according to the present invention is usually in the range of about 1 to 100 nm, particularly in the range of about 1 to 50 nm, preferably in the range of about 1 to 30 nm, more preferably in the range of 10 to 30 nm. In the range of degrees. Aspect ratio (L) of tube length (L) to outer diameter (D)
/ D) is about 5 to 10,000, especially 10 to 10
It is about 00.

The term “linear”, which is one term representing the shape of the iron-carbon composite of the present invention, is defined as follows. That is, the carbonaceous material containing the iron-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 W, and the length when the image was linearly elongated. Where Wo is the ratio, the ratio W / Wo is 0.
A shape characteristic of 8 or more, particularly 0.9 or more is meant.

Carbonaceous Material Containing Iron-Carbon Composite The iron-carbon composite of the present invention has the following properties when viewed as a bulk material. That is, in the present invention, iron or iron carbide is filled in a range of 10 to 90% of the space in the tube of the carbon tube selected from the above-mentioned nanoflake carbon tube and nested multi-walled carbon nanotube. The 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 iron-carbon composites, a carbonaceous material containing the iron-carbon composite, or iron carbide or iron carbide. It is obtained in large quantities in the form of a material that can be called an encapsulated carbonaceous material.

FIG. 4 shows an electron micrograph of the carbonaceous material of the present invention composed of the nanoflake carbon tube manufactured in Example 1 described later and iron carbide filled in the inner space of the tube.

As can be seen from FIG. 4, in the carbonaceous material containing the iron-carbon composite of the present invention, basically, almost all (particularly 99% or more) of the carbon tubes have the space ( That is, iron carbide or iron is filled in the range of 10 to 90% of the space surrounded by the tube wall of the carbon tube, and the carbon tube whose space is not filled is generally substantially absent. . However, in some cases, a very small amount of iron carbide or a carbon tube not filled with iron may be mixed.

In the carbonaceous material of the present invention, the iron-carbon composite in which 10% to 90% of the space inside the carbon tube is filled with iron or iron carbide is a main component. In addition to the iron-carbonaceous composite of the present invention,
Soot may be included. In such a case,
By removing components other than the iron-carbonaceous composite of the present invention, the purity of the iron-carbonaceous composite in the carbonaceous material of the present invention is improved, and substantially consists only of the iron-carbon composite of the present invention. Carbonaceous materials can also be obtained.

Unlike conventional materials which can only be traced by microscopic observation, a large amount of the carbonaceous material containing the iron-carbon composite of the present invention can be synthesized. It can be. Since the material of the present invention can be produced indefinitely by scaling up or repeating the process of the present invention described below, there is substantially no upper limit. In general, the carbonaceous material containing the iron-carbon composite of the present invention can be used in an amount of about 1 mg to 100 g, particularly 10
An amount of about 1000 mg can be easily provided.

The carbonaceous material of the present invention comprises 1 mg of the carbonaceous material.
In an X-ray powder diffraction measurement of X-rays of CuKα irradiated with an irradiation area of 25 mm ² or more, the peak of 40 ° <2θ <50 ° attributed to the contained iron or iron carbide was the most. Assuming that the integrated intensity of the peak showing strong integrated intensity is Ia and the integrated intensity Ib of the peak at 26 ° <2θ <27 ° attributed to the average distance (d002) between the carbon net surfaces of the carbon tube, Ratio R to Ib
(= Ia / Ib) is about 0.35 to 5, especially 0.5 to
It is preferably about 4, more preferably about 1 to 3.

In the present specification, the ratio of Ia / Ib is called an R value. This R value is such that when a carbonaceous material containing the iron-carbon composite of the present invention is observed with an X-ray diffraction area of 25 mm ² or more in X-ray irradiation area, the peak intensity is an average value of the entire carbonaceous material. It is not the encapsulation rate or the filling rate in one iron-carbon composite that can be measured by TEM analysis, but the iron-carbon or iron filling as a whole of the carbonaceous material which is an aggregate of the iron-carbon composite. It shows the average value of the rate or the inclusion rate.

The average filling rate of the carbonaceous material as a whole including a large number of the iron-carbon composites of the present invention is determined by observing a plurality of visual fields with a TEM and examining the plurality of iron-carbon composites observed in each visual field. It can also be determined by measuring the average filling factor of iron carbide or iron, and calculating the average value of the average filling factor of a plurality of visual fields. When measured by such a method, the average filling rate of iron carbide or iron as a whole of the carbonaceous material comprising the iron-carbon composite of the present invention is about 10 to 90%, particularly about 40%.
About 70%.

The iron-carbon composite of the present invention and a charcoal containing the same
Production method of raw material (first production method) The carbonaceous material containing the iron-carbon composite of the present invention is prepared by (1) adjusting the pressure to 10 ⁻⁵ Pa to 200 kPa in an inert gas atmosphere, The ratio B / A is 1 when the oxygen concentration is A (liter) and the oxygen amount is B (Ncc).
Adjusting the concentration to be × 10 ⁻¹⁰ to 1 × 10 ⁻¹ , heating the iron halide to 600 to 900 ° C. in the reaction furnace, and (2) setting the inside of the reaction furnace to an inert gas atmosphere, The pressure is adjusted to 10 ⁻⁵ Pa to 200 kPa, and a heat treatment is performed at 600 to 900 ° C. by introducing a pyrolytic carbon source.

Here, the unit of the oxygen amount B, “Ncc”
Means the volume (cc) when the gas is converted to a standard state at 25 ° C.

A source of iron carbide or iron contained therein,
Examples of the iron halide that also exhibits a function as a catalyst include iron fluoride, iron chloride, and iron bromide. Of these, iron chloride is preferable. Examples of iron chloride include FeCl ₂ , FeCl ₃ , FeCl ₂ .4H ₂ O, and FeCl ₃ .6H ₂ O, and at least one of these is used. Although the shape of these catalysts is not particularly limited, they are usually in the form of powder, for example, having an average particle diameter of about 1 to 100 μm, particularly 1 to 20 μm.
It is preferable to use it in the form of a powder of about m or in the form of a gas.

Various organic compounds can be used as the pyrolytic carbon source. For example, aromatic hydrocarbons having 6 to 12 carbon atoms such as benzene, toluene and xylene, methane, ethane, propane, butane, hexane and the like can be used. Organic compounds such as a saturated aliphatic hydrocarbon having 1 to 10 carbon atoms, and unsaturated aliphatic hydrocarbons having 2 to 5 carbon atoms such as ethylene, propylene, and acetylene are exemplified. The liquid organic compound is usually used after being vaporized. Among these, benzene, toluene and the like are preferable.

As a reaction apparatus used in the present invention, for example, an apparatus as shown in FIG. 1 can be exemplified. In the apparatus shown in FIG. 1, a reaction furnace 1 is a reaction furnace including a quartz tube, an alumina tube, a carbon tube, and the like, and includes a heating device 2. The reactor is provided with a gas inlet (not shown) and a gas suction port (not shown) for suctioning into a vacuum. The iron halide is, for example, spread thinly and spread on an iron halide preparation dish 10 such as a porcelain boat, a nickel boat, and the like.
Place in the reactor.

Step (1) In the production method of the present invention, first, iron halide as the above catalyst is heated to 600 to 900 ° C. in an inert gas atmosphere in a reaction furnace.

[0074] As the inert gas, He, Ar, Ne, a gas such as N ₂ can be exemplified. The pressure in the reaction furnace when performing the heat treatment of the catalyst in an inert gas atmosphere is, for example, 10 ⁻⁵ Pa or more.
The pressure is preferably about 200 kPa, particularly about 0.1 kPa to 100 kPa.

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 pyrolytic carbon source is
Depending on the type of pyrolytic carbon source, in general,
The temperature of the catalyst in the reactor is about 600 to 900 ° C.,
It is preferable that the temperature be about 50 to 900 ° C.

According to the study of the present inventors, it is preferable that a small amount of oxygen is present during the heating in the step (1). When a large amount of oxygen is present, iron halide is converted to iron oxide, and it is difficult to obtain a desired complex. Therefore, as the oxygen concentration in the reactor, the ratio B / A when the reactor volume is A (liter) and the oxygen amount is B (Ncc) is 1 × 10 ⁻¹⁰ to 1 ×.
The concentration is preferably 10 ^-1 , especially 1 × 10 ^{-8 to} 5 × 10 ^-3 .

In this case, as a method for introducing oxygen, various methods can be adopted. For example, an inert gas such as argon containing about 5 to 0.01% of oxygen is supplied from a gas inlet of a reaction furnace. It is preferable to add the mixed gas gradually.

Step (2) In the present invention, as the step (2), the inside of the reaction furnace containing the iron halide heated to 600 to 900 ° C. by the heat treatment in the step (1) is placed in an inert gas atmosphere. Then, a heat treatment is performed by introducing a pyrolytic carbon source from the gas inlet.

The pressure at the time of performing the heat treatment in this step (2) is about 10 ⁻⁵ Pa to about 200 kPa, particularly 1 kPa
The pressure is preferably set to about 100 kPa. Also, the process
The temperature during the heat treatment of (2) is usually 600 ° C. or higher,
Particularly, it is about 600 to 900 ° C, preferably about 750 to 900 ° C.

As a method for introducing the pyrolytic carbon source, for example, a pyrolytic carbon source such as benzene is supported by bubbling an inert gas such as an argon gas into the pyrolytic carbon source such as benzene. The inert gas may be adjusted, and the gas may be introduced little by little from the gas inlet of the reaction furnace. However, the present invention is not limited to this method, and another method may be employed. The supply rate of the inert gas carrying the pyrolytic carbon source such as benzene can be selected from a wide range, but is generally about 0.1 to 1000 ml / min, preferably about 1 to 1000 ml / liter of the reactor volume. Preferably, the speed is about 100 ml / min. At that time, if necessary, Ar, Ne, He,
An inert gas such as nitrogen may be introduced as a diluting gas.

The quantitative ratio of the iron halide to the pyrolytic carbon source may be appropriately selected from a wide range, but the amount of the pyrolytic carbon source is 10 to 500 parts by weight per 100 parts by weight of the iron halide.
It is preferably about 0 parts by weight, particularly about 50 to 300 parts by weight. When the quantitative ratio of the organic compound as the pyrolytic carbon source increases, the growth of the carbon tube is sufficiently performed, and a long-sized carbon tube is obtained.

The reaction time of step (2) varies depending on the type and amount of the raw materials, and is not particularly limited.
It is about 10 to 10 hours, especially about 0.5 to 2 hours.

After the heat treatment step of the above step (2), usually 50
~ 2000 ° C / h, preferably 70 ~ 1500 ° C / h
h, more preferably at a rate of about 100 to 1000 ° C./h to 500 ° C., so that the nanoflake carbon tube and 10 to 90% of the space in the tube
To form an iron-carbon composite composed of iron carbide or iron filled in the steel.

After the heat treatment step of step (2), (3) a step of replacing the inside of the reaction furnace with an inert gas while maintaining the temperature of step (2), and (4) a step of replacing the inside of the reaction furnace with the inert gas. 95 inside the reactor
About 0 to 1500 ° C, preferably 1200 to 1500 ° C
(5) a step of maintaining the end point temperature at the heating end point until a nested multi-walled carbon nanotube is produced, and (6) a reaction furnace at 50 ° C. / h or less, preferably 5 to 4
By performing a cooling step at a rate of about 0 ° C./h, more preferably about 10 to 30 ° C./h, the nested multi-walled carbon nanotube and 10 to 90% of the space in the tube are filled. Iron-carbon composites of iron carbide or iron can be produced.

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 the replacement in the step (3) is not particularly limited, but is about 10 ⁻⁵ to 10 ⁷ Pa, preferably 50 to 2 × 10 ⁵ Pa.
It is about Pa, more preferably about 100 to 1.2 × 10 ⁵ Pa.

The rate of temperature rise in step (4) is not particularly limited, but is generally about 50 to 2000 ° C./h, particularly 70 to 1 / h.
About 500 ° C / h, more preferably 100 to 1000 ° C
/ H is preferable.

The time for maintaining the end point temperature in the step (5) may be a time until the nested multi-walled carbon nanotubes are formed, but is generally about 2 to 30 hours.

The atmosphere at the time of cooling in the step (6) is Ar, N
e, He, an inert gas atmosphere such as nitrogen, and the pressure condition is not particularly limited, but is about 10 ^-5 to 10 ⁷ Pa, preferably 50
About 2 × 10 ⁵ Pa, more preferably about 100 to 1.2 × 10 ⁵ Pa.

Method for Improving Yield (Second Production Method) According to another embodiment of the present invention, in step (2) of the first production method, an organic iron complex is supplied together with a pyrolytic carbon source to further improve the yield. The yield of the iron-carbon composite of the present invention can be increased. In the present specification, the manufacturing method of this embodiment is referred to as “second manufacturing method”.

Examples of the organic iron complex include ferrocene, F
Examples of iron carbonyl complexes such as e (CO) ₅ include
Of these, ferrocene is particularly preferred.

The method of causing the organic iron complex such as ferrocene 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.

That is, first, as shown in FIG. 2, in a reaction furnace provided with a gas inlet (not shown) and a gas suction port (not shown), a position near the upstream side (that is, a position close to the gas inlet). ) Such as a porcelain boat containing an organic iron complex
And a charging plate 10 such as a porcelain boat containing iron halide is disposed on the downstream side (a position far from the gas inlet).

Next, as a step (1), iron halide is placed in an inert gas atmosphere at a pressure of 10 ^-5 Pa to 200 kPa.
And the ratio of B / A when the oxygen concentration in the reactor is A (liter) and the oxygen amount is B (Ncc).
Is 1 × 10 ⁻¹⁰ to 1 × 10 ⁻¹ , especially 1 × 10 ^{−8 to} 5 × 1
It is adjusted to a concentration of 0 ^-3 and heated to 600 to 900 ° C. by the heating device 2.

[0094] Subsequently, as a step (2), the reaction furnace and inert gas atmosphere, the pressure 10 ^{- 5} Pa~200kP
a, preferably at 1 to 100 kPa. On the other hand, the organic iron complex is heated to the sublimation temperature (200 ° C. in the case of ferrocene) of the organic iron complex by another heating device 3 to bring the organic iron complex such as ferrocene into a gaseous state, And a mixed gas of inert gas are 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 diluting gas. As a result, the pyrolytic carbon source, ferrocene and iron halide are present in the reactor. The system is heat treated. The conditions for this heat treatment are the same as those in the “step
The conditions are basically the same as those described for (2).

That is, the pressure during the heat treatment is about 10 ⁻⁵ Pa to 200 kPa, particularly 1 kPa to 1 kPa.
Preferably, the pressure is set to about 00 kPa. The temperature at the time of the heat treatment is usually at least 600 ° C.,
900 ° C., preferably about 750 to 900 ° C. The supply rate of the inert gas carrying the pyrolytic carbon source such as benzene can be selected from a wide range, but is generally about 0.1 to 1000 ml / min, preferably about 1 to 1000 ml / liter of the reactor volume. Preferably, the speed is about 100 ml / min. The time of 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.

In the above, the quantitative ratios of the organic iron complex, the iron halide and the pyrolytic carbon source can be selected from a wide range, but are generally preferably as follows.

The amount of the organic iron complex used is 10
It is preferably about 1 to 5000 parts by weight, more preferably about 10 to 1000 parts by weight, based on 0 parts by weight.

The amount of the pyrolytic carbon source to be used is preferably about 10 to 5000 parts by weight, particularly about 50 to 300 parts by weight, based on 100 parts by weight of the iron halide.

According to the second production method, the yield of the obtained carbonaceous material containing the iron-carbon composite is improved.

As in the case of the first production method,
After the heat treatment step (2), the nanoflakes are cooled 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. It is possible to produce an iron-carbon composite comprising iron carbide or iron filling the carbon tube and 10 to 90% of the space in the tube.

Also, after the heat treatment step of step (2), (3) a step of replacing the inside of the reaction furnace with an inert gas while maintaining the temperature of step (2), and (4) a step of replacing with an inert gas. 95 inside the reactor
About 0 to 1500 ° C, preferably 1200 to 1500 ° C
(5) a step of maintaining the end point temperature at the heating end point until a nested multi-walled carbon nanotube is produced, and (6) a reaction furnace at 50 ° C. / h or less, preferably 5 to 40 ° C
/ H, more preferably at a rate of about 10 to 30 ° C./h, thereby performing nested multi-walled carbon nanotubes and carbonization filling 10 to 90% of the space in the tube. Iron or an iron-carbon composite consisting of iron can be produced.

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 the replacement in the step (3) is not particularly limited, but is about 10 ⁻⁵ to 10 ⁷ Pa, preferably 50 to 2 × 10 ⁵ Pa.
It is about Pa, more preferably about 100 to 1.2 × 10 ⁵ Pa.

The heating rate in the step (4) is not particularly limited, but is generally about 50 to 2000 ° C./h, especially about 70 to 1 / h.
About 500 ° C / h, more preferably 100 to 1000 ° C
/ H is preferable.

The time for maintaining the end point temperature in the step (5) may be a time until the nested multi-walled carbon nanotubes are generated, but is generally about 2 to 30 hours.

The cooling atmosphere in the step (6) may be Ar, N
e, He, an inert gas atmosphere such as nitrogen, and the pressure condition is not particularly limited, but is about 10 ^-5 to 10 ⁷ Pa, preferably 50
About 2 × 10 ⁵ Pa, more preferably about 100 to 1.2 × 10 ⁵ Pa.

From the carbonaceous material obtained by the first production method or the second production method, the iron-carbon composite constituting the material can be isolated.

The iron-carbon composite obtained by the first or second production method of the present invention has the following unique properties.

A carbon tube selected from the group consisting of a nanoflake carbon tube and a nested multi-walled carbon nanotube constituting a wall 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. For electron emission applications, high linearity is an advantage.

10 to 90 of the space surrounded by the tube wall
% Is filled with iron carbide or iron. The iron carbide or iron present in the space exists in a highly developed crystalline state as is clear from the examples. Accordingly, a novel molecular magnet having excellent durability can be obtained because the inclusion body shows magnetism and the surface layer is covered with carbon.

It is known that the electrical or magnetic properties of carbon nanotubes that do not contain metal largely depend on the structure of the wall. However, in order to obtain specific electrical or magnetic properties uniformly, it is necessary to use the wall structure. Needs to be precisely controlled. For example, in hollow single-walled carbon nanotubes without inclusions, it is theoretically known that the graphene sheet is wound in an armchair type, zigzag type, or chiral type with different conductive properties, and becomes a conductor or semiconductor. Have been. However, it is extremely difficult to precisely control the wall structure with the current synthesis technology.

On the other hand, the carbon material of the present invention containing 10 to 90% of iron carbide or iron in the hollow portion of the carbon tube selected from the group consisting of the nanoflake carbon tube and the nested multi-walled carbon nanotube of the present invention Is superior in that it does not require precise control of the wall structure because its electrical or magnetic properties are mainly due to the metal contained therein rather than the wall structure made of carbon, and is easy to manufacture. In particular, in the case of a nanoflake carbon tube, the wall structure will be isotropic while maintaining the graphitic property, so that the ratio of the electrical characteristics depending on the contained metal increases,
Characteristics can be easily controlled.

The iron-carbon composite of the present invention containing iron carbide or iron and having high linearity has excellent electron emission ability, high magnetic orientation, and is suitable for use in FED (field emission display) applications. Can be

Further, even when the iron-carbon composite of the present invention is used as a conductive additive in a resin or the like, the conductivity can be improved with a small amount of the resin. Transparency, hue, etc. are not impaired.

Further, by blending the iron-carbon composite of the present invention with a resin, there is also an advantage that the strength of the resin molded body is increased.

Further, in the case where a part of the wall is opened by the chemical treatment, the iron-carbon composite of the present invention can release the contained metal and the like gradually.

[0116]

The present invention will be described in more detail with reference to the following examples.

Example 1 Using the reactor as shown in FIG. 1, an iron-carbon composite of the present invention was obtained as follows.

Step (1) Spread 0.5 g of anhydrous FeCl ₃ (manufactured by Kanto Chemical Co., Ltd.) thinly in a porcelain boat. This is installed in the center of a furnace made of a quartz tube, and the pressure in the furnace is reduced to 50 Pa. At this time,
An argon gas containing 5000 ppm of oxygen is supplied at a rate of 30 ml / min from the opposite side (left side of the reaction tube in FIG. 1) of the reaction furnace equipped with a vacuum suction line. Thus, the ratio B / A when the reactor volume was A (liter) and the oxygen amount was B (Ncc) was 2.5 × 10 ⁻³ . Then
The temperature is raised to 800 ° C. under reduced pressure.

Step (2) When the temperature reaches 800 ° C., argon is introduced and the pressure is controlled at 6.7 × 10 ⁴ Pa. On the other hand, as a pyrolytic carbon source, bubbling argon gas into a benzene tank,
A mixed gas of benzene and argon volatilized was introduced into the furnace at a flow rate of 30 ml / min per liter of the reactor volume,
As a diluent gas, an argon gas is introduced at a flow rate of 20 ml / min.

The reaction is carried out at a reaction temperature of 800 ° C. for 30 minutes, and 500 ° C.
After the temperature was lowered in 20 minutes, the heater was removed, and the mixture was air-cooled to room temperature in 20 minutes to obtain 200 mg of a carbonaceous material containing the iron-carbon composite of the present invention.

From the results of SEM observation, the obtained iron-carbon composite had an outer diameter of 15 to 40 nm and a length of 2 to 3 μm, and had a high linearity. The thickness of the wall made of carbon is 2
〜１０10 nm and was substantially uniform over its entire length.
In addition, it was confirmed by TEM observation and X-ray diffraction method that the wall was a nanoflake carbon tube having a graphitic structure in which the average distance (d002) between carbon net surfaces was 0.34 nm or less.

Further, by X-ray diffraction and EDX, it was confirmed that the iron-carbon composite of the present invention contained iron carbide.

When a large number of the iron-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 (ie,
Iron-carbon composites having various filling ratios in which the filling ratio of iron carbide to the space surrounded by the tube wall of the nanoflake carbon tube) was in the range of 10 to 80% were mixed.

Incidentally, the average filling ratio of iron carbide in the space inside the nanoflake carbon tubes or carbon nanotubes of the numerous iron-carbon composites was 40%.
Table 1 below shows the average filling ratio of iron carbide calculated by observing a plurality of visual fields of the TEM observation image of the obtained iron-carbon composite. The R value calculated from X-ray diffraction was 0.56.

[0125]

[Table 1]

FIG. 3 shows an electron microscope (TEM) photograph of one iron-carbon composite material constituting the carbonaceous material obtained in Example 1.

An electron microscope (TE) showing the presence of a large number of iron-carbon composites in the carbonaceous material obtained in Example 1
M) A photograph is shown in FIG.

FIG. 5 shows an electron diffraction pattern of one iron-carbon composite obtained in Example 1. FIG. 5 shows that a clear electron diffraction pattern was observed, indicating that the inclusions had high crystallinity. As a result of the TEM observation, the crystallization rate of the inclusions (the ratio of the area of the TEM image of the crystalline iron carbide to the area of the TEM image in the range where the iron carbide is filled) is about 100.
%Met.

FIG. 6 shows an X-ray diffraction diagram of the carbonaceous material (a collection of iron-carbon composite materials) containing the iron-carbon composite obtained in Example 1.

FIG. 7 shows an electron microscope (TEM) photograph of one of the iron-carbon composites obtained in Example 1 cut into a slice.

As can be seen from FIG. 7, in the carbonaceous material obtained in Example 1, the carbon wall surface is neither nested nor scroll-shaped, but is patchwork-shaped (so-called pap-shaped).
er mache-like or mache-like), and it was a nanoflake carbon tube.

As can be seen from FIG. 7, the shape of the nanoflake carbon tube constituting the iron-carbon composite obtained in the present example is cylindrical, and in the TEM photograph of a cross section crossing the longitudinal direction thereof. The observed graphene sheet image was not a closed ring but a discontinuous ring having many discontinuous points.

Further, when the nano-flake carbon tube constituting the iron-carbon composite of the present invention was observed by TEM, a large number of substantially linear graphene sheet images oriented in the longitudinal direction were considered as individual images. The length of the graphene sheet image was generally in the range of 2-30 nm (FIG. 3).

Further, from the EDX measurement results measured at points 1 to 20 in the tube in FIG. 7, it was found that the atomic ratio of carbon: iron was 5: 5 and almost uniform compounds were included.

Example 2 Using a reactor as shown in FIG. 1, an iron-carbon composite of the present invention was obtained as follows.

Step (1) 0.5 g of FeCl ₂ .4H ₂ O (manufactured by Kanto Chemical Co., Ltd.) is thinly spread and spread in a porcelain boat. This is installed in the center of a furnace made of a quartz tube, and the pressure in the furnace is reduced to 50 Pa.
At this time, argon gas containing 5000 ppm of oxygen is supplied at a rate of 5 ml / min from the opposite side (left side of the reaction tube in FIG. 1) of the reaction tube provided with a line for vacuum suction. Thereby, the internal volume of the reactor is set to A (liter), and the oxygen amount is set to B (Ncc).
^{Was set} to 2.5 × 10 ⁻³ . Next, the temperature is raised to 800 ° C. while maintaining the reduced pressure.

Step (2) When the temperature reaches 800 ° C., argon is introduced and the pressure is controlled at 6.7 × 10 ⁴ Pa. On the other hand, as a pyrolytic carbon source, bubbling argon gas into a benzene tank,
A mixed gas of benzene and argon volatilized was introduced into the furnace at a flow rate of 30 ml / min per liter of the reactor volume,
As a diluent gas, an argon gas is introduced at a flow rate of 20 ml / min.

The reaction was carried out at a reaction temperature of 800 ° C. for 30 minutes, the temperature was lowered to 500 ° C. in 20 minutes, then the heater was removed and air-cooled to room temperature in 20 minutes to obtain a carbonaceous material containing the iron-carbon composite of the present invention. 120 mg of material was obtained.

From the result of SEM observation, it was found that the iron-carbon composite constituting the obtained carbonaceous material had a diameter of 15 to 40 nm, a length of 2
It was highly linear at ~ 3 microns. The thickness of the carbon wall was 2 to 10 nm, and was substantially uniform over the entire length. The average distance (d002) between carbon mesh planes was determined by TEM observation and X-ray diffraction.
It was confirmed to be a nanoflake carbon tube having a graphite structure of 0.34 nm or less.

FIG. 8 shows an electron microscope (TEM) photograph (one iron-carbon composite) of the iron-carbon composite obtained in Example 2.

FIG. 9 shows an electron diffraction diagram of the iron-carbon composite obtained in Example 2. FIG. 9 shows that a clear electron diffraction pattern was observed, indicating that the inclusions had high crystallinity. As a result of TEM observation, the crystallization rate of the inclusion (the ratio of the area of the TEM image of crystalline iron carbide to the area of the TEM image in the range in which iron carbide or iron is filled) is about 1
00%.

When a large number of iron-carbon composites constituting the carbonaceous material of the present invention were observed with an electron microscope (TEM),
Iron-carbon composites having various filling ratios of iron carbide or iron in the space portion of the nanoflake carbon tube (space surrounded by the carbon wall of the nanoflake carbon tube) in the range of 10 to 80% are provided. It was mixed.

From the result of the TEM observation, it was found that in the carbonaceous material containing the iron-carbon composite of the present invention, the average filling rate of iron carbide or iron in the space inside the nanoflake carbon tube was 30%.
% (Average value as a carbonaceous material). The R value calculated from the X-ray diffraction in the same manner as in Example 1 was 0.1.
42.

[0144] The shape of the nanoflake carbon tube constituting the iron-carbon composite obtained in the present example is cylindrical, and the graphene sheet image observed in the TEM photograph of a cross section transverse to the longitudinal direction is as follows. , Not a closed ring, but a discontinuous ring having many discontinuities.

Further, when the nanoflake carbon tube constituting the iron-carbon composite of the present invention was observed by TEM, a large number of substantially linear graphene sheet images orientated in the longitudinal direction were found to be individual. The length of the graphene sheet image was generally in the range of 2-30 nm (FIG. 8).

Example 3 Using an apparatus as shown in FIG. 2, the following steps (1) and (2) were performed to obtain an iron-carbon composite of the present invention.

Step (1) Spread 0.5 g of anhydrous FeCl ₃ (manufactured by Kanto Chemical Co., Ltd.) thinly in a porcelain boat. This is installed downstream in the furnace. Ferrocene put in a porcelain boat will be installed upstream of the furnace.

The pressure inside the furnace is reduced to a pressure of 50 Pa. At this time,
An argon gas containing 5000 ppm of oxygen is supplied at a rate of 30 ml / min from the opposite side of the vacuum suction line. This allows
Let the reactor volume be A (liter) and the oxygen amount be B (Ncc)
^{Was set} to 2.5 × 10 ⁻³ . Next, the temperature is raised to 800 ° C. while maintaining the reduced pressure.

Step (2) When the reaction temperature reached 800 ° C., argon was introduced,
The pressure is controlled at 6.7 × 10 ⁴ Pa. On the other hand, ferrocene in a porcelain boat installed on the upstream side in the furnace is heated to 200 ° C. while maintaining the pressure at 6.7 × 10 ⁴ Pa.

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. As a diluting gas, an argon gas is introduced at a flow rate of 20 ml / min. 800 ℃
At a reaction temperature of 30 minutes.

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 240 mg of a carbonaceous material containing an iron-carbon composite in the reaction tube.

From the result of SEM observation, the obtained iron-carbon composite had a diameter of 15 to 40 nm and a length of 2 to 3 μm and was highly linear.

The thickness of the wall made of carbon is 5 to 1
5 nm and was substantially uniform over its entire length. The wall was confirmed by TEM observation and X-ray diffraction to be a multilayered nanoflake carbon tube having a graphite structure with an average distance (d002) between carbon mesh planes of 0.34 nm or less.

When a large number of iron-carbon composites constituting the carbonaceous material of the present invention were observed with an electron microscope (TEM),
Iron-carbon composites having various filling ratios of iron carbide or iron in the space portion of the nanoflake carbon tube (the space surrounded by the carbon wall of the nanoflake carbon tube) in the range of 25 to 90% are provided. It was mixed.

A clear electron diffraction pattern was observed for the inclusions, and the inclusions had high crystallinity. As a result of TEM observation, the crystallization ratio of the inclusions (the ratio of the area of the TEM image of crystalline iron carbide to the area of the TEM image in the range in which iron carbide or iron was filled) was about 100%.

From the results of the TEM observation, it was found that, in the carbonaceous material containing the iron-carbon composite of the present invention, the average filling rate of iron carbide or iron into the space inside the nanoflake carbon tube (average value as the carbonaceous material) Was 60%. The R value calculated from the X-ray diffraction in the same manner as in Example 1 is 1.
23.

[0157] The shape of the nanoflake carbon tube constituting the iron-carbon composite obtained in the present example is cylindrical, and the graphene sheet image observed in a TEM photograph of a cross section transverse to the longitudinal direction is as follows. , Not a closed ring, but a discontinuous ring having many discontinuities.

Further, when the nanoflake carbon tube constituting the iron-carbon composite of the present invention was observed by TEM, a large number of substantially linear graphene sheet images oriented in the longitudinal direction were observed. The length of the graphene sheet image was generally in the range of 2-30 nm.

Example 4 In a reactor as shown in FIG. 1, a reaction tube was made of carbon and used with increased heat resistance, and an iron-carbon composite of the present invention was obtained as follows.

Step (1) 0.5 g of anhydrous FeCl ₃ (manufactured by Kanto Chemical Co., Ltd.) is spread and spread in a porcelain boat. This is installed in the center of a furnace made of a quartz tube, and the pressure in the furnace is reduced to 50 Pa. At this time, an argon gas containing 5000 ppm of oxygen is supplied at a rate of 5 ml / min from the opposite side of the vacuum suction line. Thereby, the internal volume of the reactor is set to A (liter), and the oxygen amount is set to B
The ratio B / A when (Ncc) was set to 2.5 × 10 ⁻³ . Next, the temperature is raised to 800 ° C. while maintaining the reduced pressure.

Step (2) When the temperature reaches 800 ° C., argon is introduced and the pressure is controlled at 6.7 × 10 ⁴ Pa. On the other hand, as a pyrolytic carbon source, bubbling argon gas into a benzene tank,
A mixed gas of benzene and argon volatilized was introduced into the furnace at a flow rate of 30 ml / min per liter of the reactor volume,
As a diluent gas, an argon gas is introduced at a flow rate of 20 ml / min.

After reacting at a reaction temperature of 800 ° C. for 120 minutes,
The pressure is reduced to 50 Pa at 800 ° C. Then, the atmosphere was increased to 9.0 × 10 ⁴ Pa in an argon atmosphere, the temperature of the furnace was raised to 1350 ° C. in 120 minutes, then maintained at 1350 ° C. for 6 hours, cooled to 500 ° C. in 24 hours, removed from the heater, and released to room temperature. By cooling, 220 mg of a carbonaceous material containing the iron-carbon composite of the present invention was obtained.

From the results of SEM observation, the iron-carbon composite constituting the obtained carbonaceous material had a diameter of 15 to 40 nm, a length of 2
It was highly linear at ~ 5 microns. The thickness of the carbon wall was 2 to 10 nm, and was substantially uniform over the entire length. The average distance (d002) between carbon mesh planes was determined by TEM observation and X-ray diffraction.
It was confirmed that it was a nested multi-walled carbon nanotube having a graphite structure of 0.34 nm or less.

When a large number of iron-carbon composites constituting the carbonaceous material of the present invention were observed with an electron microscope (TEM),
Iron having various filling ratios in which the filling ratio of iron carbide or iron into the space of the nested multi-walled carbon nanotube (the space surrounded by the tube wall of the nested multi-walled carbon nanotube) is in the range of 10 to 50%. The carbon composite was mixed.

A clear electron diffraction pattern was observed for the inclusions, and the inclusions had high crystallinity. As a result of TEM observation, the crystallization ratio of the inclusions (the ratio of the area of the TEM image of crystalline iron carbide to the area of the TEM image in the range in which iron carbide or iron was filled) was about 100%.

From the results of TEM observation, in the carbonaceous material containing the iron-carbon composite of the present invention, the average filling rate of iron carbide or iron in the space inside the nested multi-walled carbon nanotube was 20% (carbonaceous material). Average value). The R value calculated from X-ray diffraction in the same manner as in Example 1 was 0.38.

[0167]

According to the present invention, the following remarkable effects are achieved.

According to the production method of the present invention, an iron-carbon composite having a novel structure in which 10% to 90% of the space surrounded by the carbon material wall is filled with iron carbide or iron can be easily prepared. It can be obtained in high yield and in large quantities by a simple method.

[0169] The obtained iron-carbon composite material has 10
In terms of encapsulating iron carbide or iron in up to 90%, it is clearly different in structure from a known material in which iron is present at the tip of a carbon nanotube, and has novel unique properties based on a unique structure. It is a new material.

In the iron-carbon composite of the present invention, since a metal is contained in a space surrounded by a graphite wall having excellent durability, a semi-permanent conductor or molecule which hardly deteriorates in characteristics is obtained. It has a function as a conductive wire and a magnetic substance or a molecular magnet. Therefore, the iron-carbon composite according to the present invention can be used as an electron-emitting material, an iron sustained-release material, a magnetic recording material,
Sliding materials, conductive fibrils, magnetic materials, magnetic fluids,
It is extremely useful as a superconducting material, a wear-resistant material, a semiconductor material, and the like. Also, in the present invention, the entire space inside the carbon tube is not filled with iron carbide or iron as inclusions, but 10 to 90% of the space is filled, so that production is easy. It is superior in that it has higher electric conductivity, can provide magnetism, and can expect a nano-size quantum effect as compared with a material composed of carbon nanotubes alone. In addition, since it is possible to manufacture the inclusions of iron carbide or iron as inclusions in the range of 10 to 90% of the space inside the carbon tube, the carbonaceous material containing the iron-carbon composite of the present invention having a specific inclusion ratio can be manufactured. By choosing the material,
Various physical properties such as electrical properties, magnetic properties, and specific gravity can be controlled.
Regarding the specific gravity, the encapsulation rate of 100
%, That is, a composite in which a metal such as iron is included over the entire length of the carbon tube, may have too high a specific gravity due to the included metal, making uniform dispersion in other substances difficult. However, the iron-carbon composite of the present invention has an encapsulation rate of 10-9.
Since the amount of metal included can be reduced in the range of 0%, uniform mixing becomes easy.

In particular, the iron-carbon composite comprising the nanoflake carbon tube and iron carbide or iron of the present invention has the following advantages. (a) Many starting points of electron emission. Since the possibility of electron emission from the edge of the graphene sheet is high, it is advantageous from the viewpoint of obtaining a large current density. (b) Because of its high graphitic properties, it has excellent life characteristics. (c) Familiarity with the paste is improved. With high graphitic properties,
At the time of pasting, the solvent and the compatibility with the paste agent become poor, but the nano-flake carbon tube and the iron-carbon composite composed of iron carbide or iron are easy to paste because of the effect of the edge of the graphene sheet. . (d) Good heat dissipation. (e) Structural control is easy. Since the side wall has a flake shape or a papier shape, the structure control such as cutting and surface modification becomes easy. (f) It is flexible. The flaky or papier-shaped side walls provide flexibility, and when used in a composite material or the like, can achieve both rigidity and impact resistance.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a manufacturing apparatus for performing a manufacturing method of the present invention.

FIG. 2 is a schematic view showing another example of a manufacturing apparatus for performing the manufacturing method of the present invention.

FIG. 3 shows the composition of iron constituting the carbonaceous material obtained in Example 1.
It is an electron microscope (TEM) photograph of one carbon composite.

FIG. 4 is an electron microscope (TEM) photograph showing the presence state of an iron-carbon composite in the carbonaceous material obtained in Example 1.

5 is an electron diffraction diagram of one iron-carbon composite obtained in Example 1. FIG.

FIG. 6 is an X-ray diffraction diagram of a carbonaceous material (a collection of iron-carbon composites) containing the iron-carbon composite obtained in Example 1.

FIG. 7 is an electron microscope (TEM) photograph of one iron-carbon composite obtained in Example 1 cut into a slice. The black triangle (三角) shown in the photograph of FIG. 7 indicates an EDX measurement point for composition analysis.

FIG. 8 is a graph showing iron-forming properties of the carbonaceous material obtained in Example 2.
An electron microscope (TEM) photograph of one carbon composite is shown.

FIG. 9 shows an electron diffraction pattern of the iron-carbon composite obtained in Example 2.

FIG. 10 shows a schematic view of a TEM image of a carbon tube,
(a-1) is a TEM of a cylindrical nanoflake carbon tube.
It is a schematic diagram of an image, and (a-2) is a schematic diagram of a TEM image of a nested multi-walled carbon nanotube.

[Explanation of symbols]

Reference Signs List 1 reactor 2 heating device 3 heating device 100 TEM image of nanoflake carbon tube in longitudinal direction 110 substantially linear graphene sheet image 200 TEM image of cross section almost perpendicular to longitudinal direction of nanoflake carbon tube 210 arc-shaped graphene sheet image 300 A linear graphene sheet image continuous over the entire length of the nested multi-walled carbon nanotube in the longitudinal direction 400 A TEM image of a cross section perpendicular to the longitudinal direction of the nested multi-walled carbon nanotube

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuhide Okimi, Inventor 4-1-2, Hiranocho, Chuo-ku, Osaka City, Osaka Prefecture Inside Osaka Gas Co., Ltd. (72) Ryoichi Nishida 4-chome, Hiranocho, Chuo-ku, Osaka City, Osaka No. 1-2 Inside Osaka Gas Co., Ltd. (72) Inventor Takeo Matsui 17 Nakadoji Minamicho, Shimogyo-ku, Kyoto, Kyoto Prefecture Kyoto Research Park Kansai New Technology Research Institute Co., Ltd. F-term (reference) 4G046 CA00 CA01 CB01 CC03 CC10

Claims (19)

[Claims] 1. An iron-carbon composite comprising (a) a carbon tube selected from the group consisting of a nanoflake carbon tube and a nested multi-walled carbon nanotube, and (b) iron carbide or iron, wherein An iron-carbon composite, wherein 10 to 90% of the space is filled with iron carbide or iron. 2. A linear shape, an outer diameter of 1 to 100 nm, a thickness of a wall portion made of carbon of 49 nm or less, which is substantially uniform over the entire length. The iron-carbon composite according to claim 1, wherein an aspect ratio L / D when a diameter is D is 5 to 10,000. 3. The average distance (d002) between carbon mesh planes is 0.34 nm or less when the wall of a carbon tube constituting the iron-carbon composite is measured by X-ray diffraction. Or the iron-carbon composite according to 2. 4. The carbon tube constituting the iron-carbon composite is a nanoflake carbon tube.
4. The iron-carbon composite according to any one of claims 1 to 3. 5. The iron-carbon composite according to claim 1, wherein the carbon tube constituting the iron-carbon composite is a nested multi-wall carbon nanotube. 6. A carbon tube selected from the group consisting of (a) a nanoflake carbon tube and a nested multi-walled carbon nanotube, and (b) iron carbide or iron, which accounts for 10 to 90% of the space in the carbon tube. A carbonaceous material containing iron carbide or an iron-carbon composite filled with iron. 7. In a powder X-ray diffraction measurement in which 1 mg of the carbonaceous material is irradiated with X-rays of CuKα with an irradiation area of 25 mm ² or more, 40 ° attributed to iron or iron carbide contained in the carbon tube. The integrated intensity of the peak showing the strongest integrated intensity among peaks at <2θ <50 ° is Ia
And the average distance between the carbon mesh surfaces of the carbon tube (d00
Assuming that the integrated intensity of the peak at 26 ° <2θ <27 ° attributed to 2) is Ib, the ratio R of Ia / Ib is 0.3
The carbonaceous material according to claim 6, which is 5 to 5. 8. The iron-carbon composite is linear, has an outer diameter of 1 to 100 nm, and has a wall thickness of 4 mm.
Less than 9 nm and substantially uniform over its entire length;
Aspect ratio L / D when length is L and outer diameter is D
The carbonaceous material according to claim 6 or 7, wherein is from 5 to 10,000. 9. An average distance (d002) between carbon mesh planes is 0.34 nm or less when a wall of a carbon tube constituting the iron-carbon composite is measured by an X-ray diffraction method. 9. The carbonaceous material according to any one of items 1 to 8. 10. The carbonaceous material according to claim 6, wherein the carbon tube constituting the iron-carbon composite is a nanoflake carbon tube. 11. The carbonaceous material according to claim 6, wherein the carbon tube forming the iron-carbon composite is a nested multi-walled carbon nanotube. 12. A carbon tube selected from the group consisting of (a) a nanoflake carbon tube and a nested multi-walled carbon nanotube, and (b) iron carbide or iron, which accounts for 10 to 90% of the space in the carbon tube. A method for producing a carbonaceous material containing an iron-carbon composite filled with iron carbide or iron, comprising the steps of: (1) adjusting the pressure to 10 ⁻⁵ Pa to 200 kPa in an inert gas atmosphere; The oxygen concentration of the reactor is A (liter), the oxygen volume is B
(Ncc) ratio B / A is 1 × 10 ⁻¹⁰ to 1 × 1
Adjusting the concentration to 0 ^-1 and heating the iron halide to 600 to 900 ° C. in the reaction furnace; and (2) setting the pressure in the reaction furnace to 10 ⁻⁵ Pa to 20
Adjusted to 0 kPa and introduced a pyrolytic carbon source to 600 ~
A manufacturing method comprising a step of performing a heat treatment at 900 ° C. 13. After the heat treatment step of the step (2), 50 to 2
By cooling to 500 ° C. at 000 ° C./h, the nano flake carbon tube and 10
The production method according to claim 12, wherein a carbonaceous material containing an iron-carbon composite comprising iron carbide or iron filled to 90% is produced. 14. After the heat treatment step of the step (2), (3) a step of replacing the inside of the reaction furnace with an inert gas while maintaining the temperature of the step (2), and (4) a step of replacing the inside of the reaction furnace with the inert gas. 950 inside the reactor
(5) maintaining the end point temperature at the end point of the temperature increase until a nested multi-walled carbon nanotube is generated, and (6) cooling the inside of the reactor at a rate of 50 ° C./h or less. The nested multi-walled carbon nanotube and 10 to 9
The production method according to claim 12, wherein a carbonaceous material containing an iron-carbon composite comprising iron carbide or iron filled to 0% is produced. 15. The method according to claim 12, wherein the heat treatment in the step (2) is performed in the presence of an organic iron complex. 16. The method according to claim 15, wherein the organic iron complex is a ferrocene or iron carbonyl complex. 17. The method according to claim 12, wherein the iron halide is an iron chloride. 18. The method of claim 18, wherein the iron chloride is FeCl ₂ , FeCl ₃ , FeCl ₂
The method according to claim 17 is at least one-selected from 4H ₂ O and the group consisting of FeCl ₃ · 6H ₂ O. 19. The group consisting of a pyrolytic carbon source comprising an aromatic hydrocarbon having 6 to 12 carbon atoms, a saturated aliphatic hydrocarbon having 1 to 10 carbon atoms, and an unsaturated aliphatic hydrocarbon having 2 to 5 carbon atoms. The method according to any one of claims 12 to 18, wherein the method is at least one selected from the group consisting of: