WO2005118473A1

WO2005118473A1 - Highly efficient process for producing carbon nanostructure through raw material blasting and apparatus tehrefor

Info

Publication number: WO2005118473A1
Application number: PCT/JP2004/008181
Authority: WO
Inventors: Yoshikazu Nakayama; Takeshi Nagasaka; Toru Sakai; Takeshi Hayashi; Hiroyuki Tsuchiya; Xu Li; Toshikazu Nosaka
Original assignee: Japan Science And Technology Agency; Public University Corporation, Osaka Prefecture University; Taiyo Nippon Sanso Corporation; Nissin Electric Co., Ltd.; Osaka Prefecture; Daiken Chemical Co., Ltd.
Priority date: 2004-06-04
Filing date: 2004-06-04
Publication date: 2005-12-15
Also published as: CN1960942A; JPWO2005118473A1; JP4674355B2; CN1960942B

Abstract

A process for producing a carbon nanostructure in which a carbon nanostructure is produced with high efficiency while reducing the occurrence of tar-like by-products; and an apparatus therefor. There is provided apparatus (2) for highly efficient carbon nanostructure production through raw material blasting, including reaction pipe (4) having catalyst body (12) disposed thereinside; heater (6) for heating the vicinity of the catalyst body (12) up to a temperature zone for formation of the carbon nanostructure (14); source gas supply pipe (8) for introducing source gas into the reaction pipe (4), with front end (8a) of the source gas supply pipe disposed in the vicinity of the catalyst body (12); and preheater (9) for preheating the source gas supply pipe (8) up to a temperature zone at which no tar-like products are formed from the source gas. As in the source gas supply pipe no tar-like products are formed and as over an intermediate temperature the source gas is blasted at a breath to the catalyst body, the reaction probability would be increased to thereby increase the production yield of carbon nanostructure. As most of the source gas is consumed, formation of tar-like substances is avoided in the reaction pipe (4) as well.

Description

Description Method and apparatus for producing high-efficiency carbon nanostructures by spraying raw materials

(Technical field)

The present invention relates to a method for producing carbon nanostructures from a source gas by catalytic chemical vapor deposition, and more particularly, to a method for producing carbon nanostructures from a source gas with high efficiency, and a method for producing a carbon nanostructure from a source gas. The present invention relates to a method and an apparatus for producing a carbon nanostructure capable of reducing a by-product by a tail.

(Conventional technology)

Carbon nanostructures are attracting attention as core materials of nanotechnology. The carbon nanostructure referred to in the present invention is a nano-sized substance composed of carbon atoms, such as a coiled carbon nanocoil, a tube-shaped carbon nanotube, a carbon nanotwist having a twisted carbon nanotube, There are beaded carbon nanotubes in which beads are formed on carbon nanotubes, power-pon nanobrushes with a large number of carbon nanotubes, and spherical fullerenes. In the following, the contents of the present invention will be described by exemplifying carbon nanocoils and carbon nanotubes among these many carbon nanostructures.

Carbon nanocoils were first synthesized by Amelinckx et al. (Amelinckx, X. B. Zhang, D. Bernaerts, X. F. Zhang, V. Ivanov and J. B. Nagy, SCIENCE, 265 (1994) 635) in 1994. In 1999, Lee et al. (W. Li, S. Xie, W. Liu, R. Zhao, Y. Zhang, W. Zhou and G. Wang, J. Material Sci., 34

(1999) 2745) Force Carbon nanocoils were successfully produced using a catalyst in which iron particles were coated on the periphery of a graphite sheet. All of them had low yield and were not suitable for mass production.

Accordingly, a “production method of carbon nanocoils” disclosed in Japanese Patent Application Laid-Open No. 2001-192204 made by a part of the present inventors has been developed. This technology is Catalytic vapor-phase epitaxy using hydrocarbons, etc., as raw material gases with a catalyst based on copper, tin, and iron

(CCVD method, Catalyst Chemical Vapor Deposition) This is the first example of mass production of carbon nanocoils.

Further, in the prior art in which the indium-tin-iron catalyst is improved, Japanese Patent Application Laid-Open No. 2001-310130, which was made by a part of the present investigators, discloses "Indium 'tin' iron for producing carbon nanocoils. Production method of system catalyst ”. This technique shows a method for synthesizing an indium-tin-iron catalyst from a metal organic compound, and discloses a method for mass-producing an indium-tin-iron catalyst.

On the other hand, carbon nanotubes are carbon nanostructures discovered in 1991 in the cathode deposits of carbon arc discharges by Sumio Iijima. Since then, mass synthesis methods of carbon nanotubes have been studied, and in recent years, the "method for producing carbon nanotubes" disclosed in JP-A-2002-180251 and JP-A-2002-180252 has been published.

The former is based on the thermal decomposition of an organic carbon material by a CVD method at a temperature of 400 to 500 ° C on an active substrate containing a catalytic metal in high-purity alumina containing 0.05% or less of alkali metal. This is a technique for mass-producing nanotubes. The latter is a catalyst metal from 0.001 to 0.005 on a molar / m ² active substrate formed by depositing at a rate of, the organic carbon source is thermally decomposed at a temperature of 1 100 to 1,250 ° C carbon nano This is a technique for synthesizing a large number of tubes.

As described above, the development of conventional manufacturing methods focused on developing catalysts for the mass synthesis of carbon nanostructures and at the same time improving manufacturing conditions such as synthesis temperature. Recently, however, large-scale synthesis has been successful, but the problem of generating unnecessary by-products has been raised.

FIG. 19 is a schematic configuration diagram when a conventional carbon nanostructure manufacturing apparatus 40 is used for generating carbon nanocoils. As shown in Japanese Patent Application Laid-Open No. 2001-192204, a carbon nanostructure manufacturing apparatus 40 has a heater 6 for heating a reaction area around an outer periphery of a reaction tube 4, and a heater 6 for heating the reaction area to obtain a uniform temperature. The set reaction temperature region is defined as a reaction region 10, and a catalyst 12 is arranged in the reaction region 10. Formation of carbon nanocoils made of indium 'tin' iron in catalyst 12 Catalyst was used.

Using He as a carrier gas and C ₂ H ₂ as a source gas, a mixed gas in which He and C ₂ H ₂ are mixed at an appropriate flow ratio flows in the direction of arrow c. The reaction zone 10 was set at 700 ° C., and the reaction time was set at 1 hour. As a result, on the surface of the catalyst body 12, C ₂ H ₂ was decomposed, and a carbon nanostructure 14 composed of carbon nanocoils grew.

However, it was confirmed that the tar-like by-product 16 adhered to the inner surface of the reaction tube 4 in a dispersed manner. Analysis of this tar-like by-product determined that it was an aromatic hydrocarbon. It was determined that there were very few alkyl groups and no paraffinic hydrocarbons. Analysis of the infrared spectrum of the tar-like by-product 16 obtained by the FT-IR method revealed that condensed aromatic ring substances such as naphthalene and anthracene, CH ₃ -substituted condensed aromatic ring substances, or highly condensed aromatic substances It is presumed to be a binding substance of a ring substance, or a mixture of these components.

It was found that the place where the tar-like by-products 16 adhered was the inner surface of the reaction tube 4 located before and after the reaction zone 1 °, and hardly existed on the inner surface of the reaction zone 10. The tar-like by-product 16 has a problem that the reaction tube is stained with black color, and the washing operation is troublesome. It was also confirmed that carbon nanocoils were produced at a normal density, but when the C ₂ H ₂ concentration was reduced, the growth density was also reduced. This is because the C ₂ H ₂ gas flowing in the direction of arrow e comes into contact with the catalyst 12 and is converted into carbon nanocoils 14 because the mixed gas flows through the entire cross section of the reaction tube 4. This is because the C ₂ H ₂ gas flowing away from the catalyst body 12 as it is in the direction passes without reacting, and causes a large amount of unreacted raw material gas to flow downstream.

Although the formation of tar-like by-products 16 alone results in a decrease in the yield of carbon nanocoils, when C ₂ H ₂ gas does not come into contact with the catalyst 12, the reaction itself does not take place. This is considered to be the cause of the rate decrease.

FIG. 20 is a schematic configuration diagram when a conventional carbon nanostructure manufacturing apparatus 40 is used for generating carbon nanotubes. The configuration of the carbon nanostructure manufacturing apparatus 40 is the same as that shown in FIG. 19, and differs in the following two points. The first difference is that the catalyst body 12 has a sodium content of 0.01. The catalyst was obtained by sintering Ni to the following high-purity r-alumina pellets (99.95% or more). The second difference is that a mixed gas of CH ₄ and Ar mixed at an appropriate flow ratio was allowed to flow in the direction of arrow c while maintaining the vicinity of the catalyst body at 500 ° C.

As a result, it was found that carbon nanostructures 14 composed of carbon nanotubes were formed at a normal density on the surface of the catalyst body 12 composed of pellets. However, it was confirmed that the tar-like by-product 16 adhered to the inner surface of the reaction tube 4 black before and after the reaction region 10 in the same manner as in the prior art. It was also confirmed that the growth density of carbon nanotubes did not increase beyond the normal density. It is considered that the reason for this is that CH ₄ flowing in the direction of arrow d does not contribute to the reaction, and that most of the raw material gas, CH ₄ , is used to generate tar-like by-products 16. As described above, it can be seen that conventional production methods and production equipment produce a considerable amount of tar-like by-products on the inner surface of the reaction tube and do not sufficiently improve the production yield of carbon nanostructures. Was. Recently, it has been recognized that it is urgently necessary to solve these issues in order to produce carbon nanostructures with high purity and high density.

Therefore, the method and apparatus for producing a carbon nanostructure according to the present invention can reduce the generation of tar-like by-products in the process of producing a carbon nanostructure by improving the reaction method and the reaction apparatus. The objective is to significantly improve the production yield of carbon nanostructures by efficiently reacting gas.

(Disclosure of the Invention)

The present invention has been made to solve the above problems, and a first aspect of the present invention is a method for producing a carbon nanostructure from a source gas by a catalytic chemical vapor deposition method. In the space heated to the temperature of the formation of carbon, the raw material gas in the temperature range where tar-like by-products are not generated is sprayed so as to come into contact with the catalyst body to produce carbon nanostructures. This is an efficient method for producing carbon nanostructures. Tall by-products gradually form carbon nanostructures from low temperatures The research by the authors and others has revealed that the process is caused by the decomposition and combination of the raw material gas in the process of rising to the temperature. That is, the subject of the present invention is to remove, from the reaction process, the intermediate temperature region where the source gas is decomposed and combined. For this purpose, in the present invention, the raw material gas is kept in a temperature range where the tar-like by-product is not generated (lower temperature, normal temperature or lower temperature than the intermediate temperature range), and the raw material gas is kept at the intermediate temperature. By jumping into the temperature range where carbon nanostructures are formed at once, it is possible to greatly reduce the generation of tar-like by-products. Also, since the raw material gas is directly blown toward the reaction region, the probability of reaction between the catalyst body and the raw material gas in the reaction region increases, and the production yield of carbon nanostructures can be greatly improved. Further, the catalyst body may be fixed in the reaction region, and a raw material gas may be sprayed on the catalyst body, or the catalyst body may be supplied from the catalyst body tank or the like to the reaction region as needed. .

According to a second aspect of the present invention, there is provided a method for producing a carbon nanostructure from a raw material gas by catalytic chemical vapor deposition, wherein the carbon nanostructure is brought into contact with a catalyst body in a space heated to a temperature range for generating the carbon nanostructure. As described above, this is a raw material spraying type high-efficiency carbon nanostructure manufacturing method in which a raw material gas preheated to a temperature range in which tar-like by-products are not generated is directly sprayed to generate carbon nanostructures. In the present invention, the raw material gas is preheated to a temperature range in which no tall by-product is generated, and the preheated raw material gas is jumped over the intermediate temperature and raised to the carbon nanostructure generation temperature at a stretch. Generation of tar-like by-products can be significantly reduced. The difference from the first invention is that the raw material gas is preheated. This preheating can increase the reactivity of the raw material gas, thereby increasing the reaction probability of the raw material gas in the catalyst region at an accelerated rate. Further, since the raw material gas is directly blown toward the reaction region, the reaction probability between the catalyst body and the raw material gas in the reaction region increases, and the generation density and generation efficiency of the carbon nanostructure can be greatly improved. Further, the catalyst body may be fixed in the reaction area, and a raw material gas may be sprayed on the catalyst body, or the catalyst body may be supplied from the catalyst body tank or the like to the reaction area as needed.

A third aspect of the present invention is a method for producing a raw material spray-type high-efficiency carbon nanostructure, wherein the catalyst body is composed of a catalyst structure. The catalyst body comprises a catalyst structure By doing so, the catalyst body can be placed only in the reaction region, so that the catalyst body and the source gas can be reacted with high efficiency. Furthermore, since the carbon nanostructure is formed on the surface of the catalyst structure, the carbon nanostructure can be collected with higher efficiency than the catalyst structure.

According to a fourth aspect of the present invention, there is provided a method for producing a carbon nanostructure, wherein the catalyst structure has at least one of a plate structure, a layer structure, a lattice structure, a porous structure and a fibrous structure. is there. According to the present invention, the structure of the catalyst structure can be selected according to the type of the catalyst structure of the carbon nanostructure to be produced. By using a catalyst structure having a layered structure, a lattice structure, a porous structure, or a fibrous structure having a large surface area, a carbon nanostructure can be produced with high efficiency. Further, by using the plate-shaped catalyst structure, the carbon nanostructure can be easily recovered.

A fifth aspect of the present invention is a method for producing a raw material spray-type high-efficiency carbon nanostructure, wherein the catalyst body is composed of catalyst powder. By forming the catalyst from the catalyst powder, the catalyst can be easily supplied as needed. Further, the carbon nanostructure formed on the surface of the catalyst powder constituent particles can be easily recovered by flowing out the catalyst powder.

According to a sixth aspect of the present invention, there is provided a raw material for supplying the catalyst powder to a reaction region in a space heated to a temperature range for generating carbon nanostructures, and heating the catalyst powder to the temperature range for generation. This is a spray type high efficiency carbon nanostructure manufacturing method. According to the present invention, the catalyst powder can be supplied to the reaction region as needed, and the raw material gas and the catalyst powder can be reacted with high efficiency.

A seventh aspect of the present invention is a raw material spraying type high-efficiency monobon nanostructure manufacturing method for supplying the catalyst powder from a catalyst powder supply pipe into a space heated to the generation temperature range. By supplying the catalyst powder from the catalyst powder supply pipe, a necessary amount can be appropriately supplied to the reaction region. Further, by heating the catalyst powder supply pipe, the catalyst powder heated to the production temperature range can be supplied, and can react with the raw material gas immediately.

According to an eighth aspect of the present invention, the raw material gas mixed with the catalyst powder is mixed with the raw material gas in the generation temperature range. This is a method for producing high-efficiency carbon nanostructures by spraying raw materials into the space heated up to the maximum. By appropriately adjusting the mixing ratio of the raw material gas and the catalyst powder, the carbon nanostructure can be manufactured with high efficiency. Furthermore, by heating the mixed gas, the raw material gas and the catalyst powder can be preheated to the same temperature. When introduced into the reaction zone, the mixed gas is instantly heated to the generation temperature zone, and the carbon nanostructure Can be manufactured with high efficiency.

According to a ninth aspect of the present invention, there is provided a raw material spraying type high-efficiency carbon nanostructure in which a catalyst powder in a space heated to the production temperature range is stirred and the raw material gas is blown onto the catalyst powder. It is a manufacturing method. By stirring the catalyst powder, the raw material gas can be efficiently brought into contact with the catalyst powder, and the carbon nanostructure can be manufactured with high efficiency. As a stirring method, a vibration method using ultrasonic vibration or the like, a rotation method of rotating a rotating plate or a container itself to which the catalyst powder is supplied, and a swing plate provided in the reaction region are provided. A swinging method of swinging or other known methods can be used. '

A tenth aspect of the present invention is a method for producing a carbon nanostructure in which a preheating temperature of a raw material gas is set at 300 ° C. or lower. For example, the temperature at which tar-like by-products from the hydrocarbon is produced which is used as a raw material gas is _{3 0 0 ° C~6 0 0 °} C, a temperature that carbon nanostructure from a hydrocarbon is produced catalyst Depending on the type of force, the force is somewhat more than 550 ° C, and it is considered that the force is efficiently from 600 ° C to 1200 ° C. Therefore, if the preheating temperature of the raw material gas is controlled to 300 ° C. or lower and the preheated raw material gas is sent to the reaction zone at 600 ° C. or higher at a stretch, the raw material gas becomes a tar-like by-product. In principle, no tar-like by-products are generated because they do not pass through the formation temperature range. According to a eleventh aspect of the present invention, there is provided an apparatus for producing a carbon nanostructure from a raw material gas by a catalytic chemical vapor deposition method, wherein a heating device for heating a reaction region to a temperature range for generating a carbon nanostructure is provided. A source gas supply pipe for introducing a source gas into the reaction region is provided, and a source gas outlet thereof is disposed in the reaction region. The source gas in a temperature range where tar-like by-products are not generated is supplied to the source gas outlet. This is a high-efficiency carbon nanostructure production system that sprays raw materials onto the catalyst. Since the temperature of the raw material gas is in the temperature range where tar-like by-products are not generated, the temperature of the raw material gas Since the structure is such that no raw by-products are generated and the raw material gas is blown directly to the catalyst from the raw material gas outlet, the raw material gas comes into contact with the catalyst with a high probability to efficiently produce a carbon nanostructure. Is converted and the generation of tar-like by-products can be reduced sharply. Since much of the raw material gas is consumed in the catalytic reaction, the formation of tar-like substances in the reaction tube is also strongly suppressed.

According to a twelfth aspect of the present invention, there is provided an apparatus for producing a carbon nanostructure from a raw material gas by a catalytic chemical vapor deposition method, wherein a heating device for heating a reaction region to a temperature range for generating a carbon nanostructure is provided. A source gas supply pipe for introducing a source gas into the reaction area is provided, and a source gas outlet thereof is arranged in the reaction area. The source gas supply pipe extends to a temperature range where tar-like products are not generated from the source gas. This is a raw material spraying type high-efficiency single-bon nanostructure manufacturing apparatus which comprises a preheating device for preheating the raw material gas and blows the preheated raw material gas to the catalyst from the raw material gas outlet. In the preheating temperature range, no tar-like products are generated inside the raw material gas supply pipe, and the preheated raw material gas comes into contact with the catalyst with high accuracy because the preheated raw material gas is directly blown from the raw material gas outlet to the catalyst. Thus, carbon nanostructures are produced with high efficiency. Therefore, as in the case of the above-described apparatus, much of the raw material gas is consumed in the catalytic reaction, so that the generation of tar-like substances in the reaction tube can be prevented.

According to a thirteenth aspect of the present invention, there is provided an apparatus for producing a carbon nanostructure from a source gas by a catalytic chemical vapor deposition method, wherein a heating device for heating a reaction region to a temperature range for producing a carbon nanostructure is provided. A mixed gas supply pipe for introducing a mixed gas of the raw material gas and the catalyst body is provided in the reaction area て, and the mixed gas outlet is arranged in the reaction area, and a temperature at which tar-like products are not generated from the mixed gas. This is a raw material spraying type high efficiency carbon nanostructure manufacturing apparatus in which a preheating device for preheating the mixed gas supply pipe to a region is provided, and the preheated mixed gas is blown to the reaction region. No tar-like products are generated inside the mixed gas supply pipe in the preheating temperature range. The mixed gas blown from the mixed gas outlet to the reaction region is instantaneously heated to the generation temperature, and is efficiently contacted with the raw material gas in the mixed gas by being sprayed with the catalyst, so that the carbon nanostructure can be efficiently formed. Can be generated. Therefore, since much of the raw material gas is consumed in the catalytic reaction, the formation of tar-like substances in the reaction tube can be prevented. According to a fifteenth aspect of the present invention, there is provided a catalyst supply pipe for supplying a catalyst in the reaction region, a preheating device for preheating the catalyst supply pipe is provided, and the raw material is added to the preheated catalyst. It is a raw material spraying type high efficiency carbon nanostructure manufacturing equipment that blows gas. By supplying the catalyst body to the reaction zone through the catalyst supply pipe for supplying the catalyst body, a required amount of catalyst powder can be supplied. Further, by preheating the catalyst body by the preheating device, the catalyst body supplied to the reaction region instantaneously reaches the generation temperature and can react with the raw material powder.

A fifteenth aspect of the present invention is a raw material spraying type high-efficiency carbon nanostructure manufacturing apparatus, which is provided with a stirring device for stirring the catalyst body in the reaction region, and blows a raw material gas to the stirred catalyst body. By stirring the catalyst powder, the raw material gas can be efficiently brought into contact with the catalyst powder, and the carbon nanostructure can be manufactured with high efficiency. The stirrer includes a vibrating means using ultrasonic vibration, a rotating means for rotating a rotating plate or rotating a container to which the catalyst powder is supplied, and a swinging plate provided in the reaction area for swinging. It can be constituted by a rocking means for moving or other known means. Further, the catalyst may be stirred after a predetermined amount of the catalyst is deposited in the reaction zone where the reaction zone is located, or the catalyst may be stirred while the supply of the catalyst is continued.

A sixteenth aspect of the present invention is a raw material spraying type high efficiency carbon nanostructure manufacturing method in which the catalyst body is a catalyst for manufacturing carbon nanocoils. If a carbon nanocoil production catalyst is used, carbon nanocoils can be selectively produced from hydrocarbons. Therefore, the method of the present invention can be used to reduce tar-like by-products and to produce carbon nanocoils with high density and high efficiency. Can be. As the carbon nanocoil production catalyst, a metal carbide catalyst, a metal oxide catalyst or a metal catalyst containing a transition metal element can be used. The transition metal element means a transition element shown in the periodic table, specifically, Sc to Cu in the fourth cycle, Y to Ag in the fifth cycle, and La to A in the sixth cycle. u and so on. Assuming that an element selected from the above transition metal elements is A, AI n C, AS n C, AI n Sn C, or the like can be used as a catalyst for producing a carbon nanostructure as the metal carbide. Further, as the metal oxide, a carbon nanostructure such as AInO, ASnO, AInSnO, AA1SnO or ACrSnO is used. The metal-based catalyst may be AAl Sn, AC r Sn, AI n Sn, or the like. Further, as a suitable metal catalyst, a metal catalyst containing an Fe element as a transition metal element can be used as a catalyst for producing a carbon nanostructure. More specifically, as _{_{_{F e x I n y C z}}} , F e x Sn y C z or _{_{_{F e x I n y C z}}} Sn w carbon nano structure creation catalyst for producing an F e based metal carbide catalyst such as it can be used, more preferred composition ratio of the metal carbide catalysts _{_{_{F e 3 I nC 0. 5}}} , F e 3 S n C or F e ₃ I n preparative _{_{_{_{v C 0. 5 S n w}}}} (0≤ v < 1, W≥0). Further, as the carbon nanostructure production catalyst, using the _{_{_{F e x I n y Sn z}}} , F e based metal catalyst such as _{_{F e X A 1 y S n}} z or _{_{F e x C r y S n}} z The more preferable composition ratio is F e ₃ I n _y S n _z ( _y ≤ 9, _z ≤ 3), F e _x A 1 _y S n _z ( _y ≤ 1, _z ≤ 3) or F e C r _y S n _z (y≤1, z≤3). By selecting a catalyst according to the purpose from these metal catalysts, a carbon nanostructure can be produced with high efficiency.

A seventeenth aspect of the present invention is a method for producing a high-efficiency carbon nanostructure by spraying a raw material, wherein the raw material gas contains at least one of acetylene, arylene, ethylene, benzene or toluene, alcohol or methane. These source gases are suitable source gases particularly for producing carbon nanostructures among hydrocarbons, and can mass-produce carbon nanostructures without generating tar-like by-products. According to an eighteenth aspect of the present invention, there is provided a method for producing a high-efficiency carbon nanostructure in which the carbon nanostructure is a carbon nanocoil, a carbon nanotube, a carbon nanotwist, a carbon nanotube with beads, a carbon nanobrush or fullerene. Is the way. A specific carbon nanostructure can be selectively mass-produced by changing the type of the catalyst or by modulating the generation temperature of the reaction zone.

(Brief description of drawings)

FIG. 1 is a schematic configuration diagram when a raw material spraying type high efficiency carbon nanostructure manufacturing apparatus 2 according to the present invention is used for manufacturing carbon nanocoils.

FIG. 2 is an overall configuration diagram in the case where the accessory spraying apparatus is combined with the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus 2 shown in FIG. FIG. 3 is an electron microscope image of a 10,000-fold carbon nanocoil obtained under condition 1 (standard concentration 1 to 2).

Figure 4 is an electron microscope image of a 5,000-fold carbon nanocoil obtained under condition 1 (standard concentration 1Z2).

Figure 5 is an electron microscope image of a 10000-fold carbon nanocoil obtained under condition 2 (standard concentration 1Z4).

Fig. 6 is an electron microscope image of a 5,000-fold carbon nanocoil obtained under condition 2 (standard concentration 1Z4).

Figure 7 is an electron microscope image of a 10,000-fold carbon nanocoil obtained under condition 3 (standard concentration 1-8).

Figure 8 is an electron microscope image of a 30,000-fold carbon nanocoil obtained under condition 3 (1/8 of the reference concentration).

Figure 9 is an electron microscope image of a 10,000 times carbon nanocoil obtained under condition 4 (identical to the reference concentration).

Figure 10 is an electron microscope image of a 5,000-fold carbon nanocoil obtained under condition 4 (identical to the reference concentration).

Figure 11 is an electron microscope image of a 10,000-fold carbon nanomaterial obtained under condition 5 (2/3 of the reference concentration).

Figure 12 is an electron microscope image of a 10,000-fold carbon nanostructure obtained under condition 6 (1/3 of the reference concentration).

FIG. 13 is a schematic configuration diagram when the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus 2 according to the present invention is used for manufacturing carbon nanotubes.

FIG. 14 is a schematic configuration diagram when a catalyst powder is used as a catalyst in the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention.

FIG. 15 is a schematic configuration diagram in the case where a catalyst powder supply pipe is provided in the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention.

FIG. 16 is a schematic configuration diagram in the case where a mixed gas supply pipe is provided in the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention. FIG. 17 is a schematic configuration diagram in a case where a stirrer 17 is attached to the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus 2 according to the present invention.

FIG. 18 is a schematic configuration diagram of each gas supply pipe 8 according to the present invention and its gas outlet.

FIG. 19 is a schematic configuration diagram when a conventional carbon nanostructure manufacturing apparatus 40 is used for generating carbon nanocoils.

FIG. 20 is a schematic configuration diagram when a conventional carbon nanostructure manufacturing apparatus 40 is used for generating carbon nanotubes.

(Best mode for carrying out the invention)

The present inventors have conducted intensive studies on the mechanism of the formation of tar-like substances by-produced in the production of carbon nanostructures. As a result, the raw material gas molecules undergo self-decomposition in a specific temperature range. They found that they formed an aromatic ring while associating, and that the aromatic rings condensed to form a macromolecule, which resulted in the formation of a macromolecule.

When the infrared absorption spectrum of the tar-like by-product was measured by the FTIR method, a number of absorption peaks appeared, and the assignment of molecular vibration was determined for each absorption wave number. The results were as follows.

3 0 4 7 CH stretching vibration of aromatic nucleus

2 9 2 0 aliphatic C H stretching vibration

1 5 9 7 C = C stretching vibration of aromatic nucleus

1 5 0 4 C = C stretching vibration of aromatic nucleus

1 4 5 0 C = C stretching vibration of aromatic nucleus

1 3 8 9 CH ₃ bending vibration

9 5 7 Out-of-plane bending vibration of aromatic nucleus From the above results, it can be concluded that the tar-like substance is aromatic hydrocarbon. The peak at wavenumber 292 (cm- ¹ ) is considered to be an alkyl group, but its absorption intensity is much smaller than other absorption intensities, so the alkyl group is very small, It is determined that there is almost no paraffinic hydrocarbon content.

According to the infrared spectrum, the tar-like substances are naphthalene having two benzene rings, anthracene having three benzene rings, a condensed aromatic ring substance obtained by condensing a large number of benzene rings, and a CH ₃ substituted substance of these condensed aromatic rings. Is determined. After searching and examining the standard charts, no identifiable charts were found. Therefore, it can be determined that the pitch is a certain kind of pitch.

In addition, mass spectrometry was performed on tar-like substances. The mass spectrometer used is a model that can measure substances with a molecular weight of 1000 or less. With this mass spectrometer, a mass spectrum with a molecular weight of 1000 or less could not be observed. This means that tar-like substances are composed of macromolecules with a molecular weight of 1000 or more. When both the infrared spectrum and the mass spectrum are combined, it is judged that these macromolecules are mainly condensed aromatic ring substances obtained by condensing a large number of C ₆ H ₆ . The process of forming such a condensed aromatic ring substance from C ₂ H _{2 as the} raw material gas is presumed to be a two-step reaction consisting of the association reaction of (1) and the polymerization reaction of (2).

(1) 3 C ₂ H ₂ → C ₆ H ₆

(2) nC ₆ H ₆ → (C ₆ H ₆ ) _n

Next, the temperature range in which these polymerization reactions occur was examined. The catalyst was removed from the reaction zone shown in FIGS. 19 and 20, and the temperature of the reaction zone was variously changed, and the amount of the tar-like substance deposited on the inner surface of the reaction tube was examined. As a result, it was found that these polymerization reactions occur in the range of 300 ° C to 600 ° C.

The discovery of this polymerization temperature range leads to very important conclusions. That is, since no polymerization reaction occurs in a temperature range of 300 ° C. or lower and a temperature range of 600 ° C. or higher, it is concluded that tar-like substances are not generated when C ₂ H ₂ is used.

According to the study of the present inventors, the temperature range in which carbon nanocoils are generated using C ₂ H ₂ as a raw material gas using an indium-tin-iron-based catalyst is 550 ° C. or higher, preferably 600 ° C. It is known to be ~ 1200 ° C. That is, above 550 ° C, the following autolysis reaction of C ₂ H ₂ occurs.

C ₂ H ₂ → 2 C + H ₂

Therefore, without producing tar-like substances from C ₂ H ₂ , carbon nanocoils To generate, without passed intermediate temperature region of 300 ° C. to 600 ° C, consisting of C ₂ H ₂ need be remarkably at once 600 ° C region from below 300 ° C. In other words, the C ₂ H ₂ gas is set at a temperature in the range of low temperature to (normal temperature) to 300 ° C, and the raw material gas is blown into the catalyst region set at 600 ° C or more at a stretch, thereby reducing the temperature. This makes it possible to eliminate the formation of repellent substances.

In order to set the C ₂ H ₂ gas to a temperature in the range of low temperature (normal temperature) to 300 ° C, there are two cases: a low temperature or normal temperature raw material gas outside the reactor is directly introduced into the catalyst region; Is preheated to a temperature of 300 ° C or less, and this preheated raw material gas is introduced into the catalyst region in two ways. The preheating method includes a method of preheating outside the reaction tube and a method of preheating inside the reaction tube. Either of these methods is included in the method of the present invention.

By changing the type of catalyst, carbon nanostructures other than carbon nanocoils can be generated, and the temperature range for the formation of tar-like substances slightly varies depending on the type of catalyst. It is also known that the temperature range for forming carbon nanostructures varies somewhat depending on the type of catalyst.

For example, according to Japanese Patent Application Laid-Open No. 2002-180251, a high purity alumina pellet catalyst containing Ni metal with CH ₄ content of less than 0.05% using CH ₄ as a raw material gas has a carbon nanotube temperature of 400 ° C. The above is selectively generated. In experiments conducted by the present inventors, the temperature range in which tar-like substances were generated by this catalyst was in the range of 250 ° C to 400 ° C.

Therefore, if this Ni metal-containing high-purity alumina pellet catalyst is used, if the raw material gas such as CH ₄ is set at 250 ° C or less and this raw material gas is blown into the catalyst body at 400 ° C or more at once, tar The desired carbon nanotubes can be produced without producing a carbonaceous material.

More specifically, a method in which a raw material gas cooled to a low temperature is directly blown into the catalyst, a method in which a room temperature raw material gas is directly blown into the catalyst, and a method in which a low temperature or room temperature raw material gas is preheated to 250 ° C or less, There is a method of blowing the preheating gas into the catalyst. In the preheating method, various deformation patterns can be designed such that the raw material gas at room temperature may be preheated to 250 ° C or less outside the reaction tube, or may be preheated to 250 ° C or less in the reaction tube. . Izu In any case, it is important to keep the raw material gas in a temperature range where tar-like substances are not generated, and it is the gist of the invention to blow this raw material gas directly into the catalyst.

If the source gas and catalyst are changed, the temperature range for the formation of tar-like substances slightly changes, but it is a relatively low temperature range. In addition, the temperature range in which carbon nanostructures are selectively formed is a relatively low temperature range, which does not overlap with the tar-like substance formation temperature range. Therefore, the raw material gas is kept in a temperature range where tar-like substances are not generated, and this raw material gas is blown into the catalyst in the carbon nanostructure generation temperature range at a stretch to remove tar-like by-products. It is possible to selectively generate carbon nanostructures by rapidly decreasing.

According to the above-mentioned method, since a tar-like substance is not produced as a by-product, a reflective effect of increasing the production density and the production yield of the carbon nanostructure can be obtained. In order to further enhance the production yield of carbon nanostructures, the present invention employs the following measures.

In a conventional carbon nanostructure manufacturing apparatus, the cross-sectional area of the reaction tube through which the raw material gas flows is configured to be much larger than the cross-sectional area of the catalyst in that direction. The raw material gas flowing in contact with the catalyst surface causes a catalytic reaction, but the raw material gas that passes far from the catalyst simply passes through without being reacted.

In a reaction tube having such a large cross-sectional area, the mixed gas of the carrier gas and the raw material gas flowing inside was flowing at a low speed in order to increase the probability of contact with the catalyst. At low speed, the mixed gas is in a laminar flow state, and the carrier gas He and the raw material gas C ₂ H ₂ are not uniformly mixed, and the concentration of the raw material gas is partially biased and mixed in the reaction tube. There is likely to be a partial bias in the gas temperature of the gas.

Therefore, in the present invention, the above-mentioned raw material gas is intensively sprayed onto the catalyst surface, and by blowing the raw material gas, the contact probability between the raw material gas and the catalyst surface is drastically improved, and the generation probability of carbon nanostructures is increased. Adopt a method to

In order to realize a method of intensively blowing a source gas (room temperature source gas or preheated source gas) onto the catalyst surface, the apparatus of the present invention uses a source gas supply pipe for introducing the source gas into the reaction tube separately from the reaction tube. The source gas outlet of the supply pipe is disposed near the surface of the catalyst body. In other words, the raw material gas or raw material A mixed gas of a gas and a carrier gas is introduced.

With such an apparatus configuration, the raw material gas intensively comes into contact with the surface of the catalyst body, and the generation probability of carbon nanostructures is drastically increased. At the same time, even if the concentration of the raw material gas flowing through the raw material gas supply pipe is set lower than before, the generation yield of carbon nanostructures remains the same as before or only because the generation probability increases. Can be increased.

In addition, since the cross-sectional area of the source gas supply pipe is relatively small, when the source gas or a mixed gas of the source gas and the carrier gas is blown from the source gas outlet, uneven temperature and concentration within the cross-sectional area are reduced. Unthinkable. In that sense, the source gas can come into contact with the catalyst at a uniform temperature and a uniform concentration, and the carbon nanostructure can grow relatively uniformly on the surface of the catalyst.

As the raw material gas used in the present invention, an iodine-containing organic gas such as thiophene, a phosphorus-containing organic gas, a hydrocarbon gas, or the like can be used. Among them, hydrocarbons are preferable because unnecessary elements are not added. Hydrocarbons include alkane compounds such as methane and ethane, alkene compounds such as ethylene and butadiene, alkyne compounds such as acetylene, aryl hydrocarbon compounds such as benzene, toluene, and styrene, and condensed rings such as indene, naphthalene, and phenanthrene. Aromatic hydrocarbons, cyclopropanes, cyclohexanes such as cyclopentenes, cyclopentin compounds such as cyclopentenes, and alicyclic hydrocarbon compounds having condensed rings such as steroids can be used. It is also possible to use a mixed hydrocarbon gas in which two or more of the above hydrocarbon compounds are mixed. In particular, low molecular weight hydrocarbons, for example, acetylene, arylene, ethylene, benzene, and toluene are preferable.

The carrier gas used in the present invention is a gas capable of transporting a source gas, and for example, He, Ne, Ar, N ₂ , H _{2 and the} like can be used. The gas flowing through the source gas supply pipe may be only the source gas or a mixed gas of the source gas and the above-mentioned carrier gas. The carrier gas is preferably used as the gas flowing through the reaction tubes except the source gas supply tube, but the carrier gas may be partially mixed with the carrier gas.

When the gas flowing into the source gas supply pipe is a mixture of source gas and carrier gas In such a case, the concentration ratio of the mixed gas can be freely determined in consideration of the amount of carbon nanostructure generated. Compared to conventional equipment without a source gas supply pipe, even if the concentration of the source gas is lowered, the probability of S response is increased by the source gas spraying method. The above can be secured.

In order to directly blow the raw material gas to the catalyst heated to 600 ° C to 1200 ° C in the reaction tube, the raw material gas outlet of the raw material gas supply pipe is arranged near the catalyst, The source gas is arranged and configured to be directly blown onto the surface of the catalyst body. The source gas supply pipe only needs to be one or more, and the source gas outlet is formed in various shapes such as a round hole and a rectangular hole so as to increase the contact area of the source gas with the surface of the catalyst. It is desirable to be done.

The source gas blown from the source gas supply pipe is set in a temperature range where tar-like substances are not generated. This temperature range is from low temperature (normal temperature) to the lowest temperature at which tar-like substances are formed. Therefore, it is not necessary to heat the source gas in order to blow the source gas at a low or normal temperature. However, in order to increase the reactivity of the raw material gas, it is desired to preheat the raw material gas to a temperature lower than the minimum temperature for producing tar-like substances.

There are two methods for preheating the source gas. The first method is a case where a raw material gas is preheated outside a reaction tube, and the preheated gas is introduced into a raw material gas supply tube in the reaction tube. The second method is a case where a source gas at a low temperature or a normal temperature is introduced into a source gas supply pipe, and the source gas supply pipe is heated to heat the internal source gas.

In the former case, that is, when the source gas heated outside is introduced into the source gas supply pipe, it is not necessary to provide a heater for heating the supply pipe around the source gas supply pipe. In other words, this case is included when the temperature range of the source gas introduced into the source gas supply pipe is from low temperature to (normal temperature) to the lowest temperature at which tar-like substances are generated.

In the latter case, that is, in the case of heating the source gas supply pipe, a heater for heating the supply pipe is provided around the source gas supply pipe. The raw material gas is preheated by the heater for heating the supply pipe in a temperature range in which tar-like substances are not generated. This preheating temperature depends somewhat on the type of the raw material gas, and may be set at 300 ° C. or less for C ₂ H ₂ . In order to increase the reactivity with the catalyst, it is preferable that the temperature is set to the maximum temperature of about 300 ° C. In the present invention, most of the raw material gas is converted into carbon nanostructures on the surface of the catalyst body, and the amount of the raw material gas flowing downstream unreacted is extremely small. Therefore, the formation of tar-like products in the downstream region of the reaction tube can be rapidly reduced. In other words, tar-like substances are hardly produced in Honmei! Due to /, the phenomenon that tar-like by-products adhere to the upstream and downstream sides of the reaction zone is almost eliminated.

[Example 1: Production of carbon nanocoil]

FIG. 1 is a schematic configuration diagram when a raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention is used for manufacturing carbon nanocoils. In the raw material spraying type high-efficiency carbon nanostructure manufacturing apparatus 2, a heater 6 for heating a reaction area is arranged on the outer periphery of a reaction tube 4, and a uniform reaction temperature area is defined as a reaction area 10 by the heater 6 for heating a reaction area. . The catalyst 12 is disposed in the reaction region 10.

A small diameter source gas supply pipe 8 is disposed in the reaction pipe 4, and the supply pipe tip 8 a reaches the inside of the reaction region 10, and the supply pipe tip 8 a is a catalyst body 12. It is located in the vicinity of. A heater 9 for supply pipe heating is arranged around the source gas supply pipe 8, and the whole of the source gas supply pipe 8 is heated and held in a temperature range where tar-like substances are not generated. In Examples 1 to 6, the nozzle-shaped source gas supply pipe 8 is used. The above-described reaction tube 4 is a quartz tube having a cross-sectional diameter (outer diameter) of 33 mm (inner diameter 28 mm), and the source gas supply pipe 8 is made of SUS having an outer diameter of 3.2 mm and an inner diameter of 1.6 mm. Piping is used. The catalyst body 12 is a quartz glass substrate on which an indium-tin-iron-based catalyst is formed. The method for producing an aluminum-tin-iron catalyst is described below.

First, 8.1 g of indium octylate (manufactured by Daiken Chemical Industry Co., Ltd.) and 0.7 g of tin octoate (manufactured by Daiken Chemical Industry Co., Ltd.) are mixed in toluene and uniformly dissolved by ultrasonic vibration. . This organic solution is applied on a 10 mm square quartz glass substrate with a brush, and dried with warm air to form an organic film.

The quartz glass substrate was put into a heating furnace at 500 ° C. for 20 minutes to thermally decompose the organic components to form an indium tin film. The thickness of the indium tin film was 300 nm. By vacuum deposition to Injiumu 'tin layer on the glass substrate to form a iron layer having a thickness of 2 0 n _m, to form an indium-tin-iron-based catalyst. Carry gas is high purity He (purity 99.999 V o 1%) manufactured by Taiyo Toyo Oxygen Co., Ltd., and C ₂ H ₂ is general dissolved acetylene (purity 98 V o 1% or more) manufactured by Sangas Nichigo Co., Ltd. used. The pressure of the carrier He is 1 atm, the flow rate is 0.8 cm / s, the reaction zone temperature is 700 ° C, and the reaction time is 30 minutes. This condition is common to the following three embodiments.

FIG. 2 is an overall configuration diagram in a case where an accessory device is combined with the carbon nanostructure manufacturing apparatus shown in FIG. He is supplied from the carrier gas container 21 via a valve 23, the flow rate is controlled by a mass flow controller 25, and He is supplied to a carrier gas supply pipe 31 via a valve 29.

The He whose flow rate is controlled by the mass flow controller 26 is also supplied to the source gas supply pipe 8 via the valve 28. On the other hand, C ₂ H ₂ is supplied from the source gas container 22 via the valve 24. This C ₂ H ₂ is a mass flow controller

The flow rate is controlled by 27 and supplied to the raw gas supply pipe 8 via the pulp 30. Therefore, a mixed gas of He and C ₂ H ₂ is supplied to the source gas supply pipe 8.

Further, after growing the carbon nanostructure, which is a carbon nanocoil, on the catalyst body 12, the passing gas flows to the tar trap 32 containing the coolant 32a cooled to the ice temperature. The tar-like by-product cooled by the tar trap 32 is trapped, and the residual gas flows from the exhaust pipe 33 in the direction of arrow f.

As described above, He flows in the reaction tube 4 in the direction of the arrow a, and the mixed gas of He and C ₂ H ₂ flows in the source gas supply tube 8. Each concentration condition was performed under three conditions: Condition 1, Condition 2 and Condition 3.

Under condition 1, the source gas supply pipe 8 contains He = 100 (SCCM) and C ₂ H ₂ =

A mixed gas of 30 (SCCM) was flown, and He = 130 (SCCM) was flowed in the reaction tube 4. The concentration ratio of C ₂ H _{2 to} the whole is 30/260 X 100 = 1 1.5

(vo 1%). The C ₂ H ₂ concentration ratio in the conventional manufacturing apparatus without the source gas supply pipe 8 is 23 (vo 1%), and this 23 (vo 1%) is the reference concentration. Set to 2.

Under condition 2, a mixed gas of He = 50 (SCCM) and C ₂ H ₂ = 15 (SCCM) flows through the raw material gas supply pipe 8, and He = 195 (SCCM) flows through the reaction pipe 4. Streamed. The concentration ratio of C ₂ H _{2 to} the whole is 15/260 x 100 = 5.8 (vo 1%), which is set to 1/4 of the reference concentration.

Under condition 3, the source gas supply pipe 8 has He = 25 (SCCM) and C ₂ H ₂ = 8

The mixed gas of (SCCM) was flowed, and He = 227 (SCCM) was flowed in the reaction tube 4. The concentration ratio of C ₂ H _{2 to} the whole is 8 × 260 × 100 = 3.1 (vo 1%), which is set to the reference concentration of 1Z8.

The state of formation of the carbon nanocoils on the catalyst body 12 is determined from an electron microscope image, and is indicated by 〇 when the generation rate is good, and X when the generation rate is not good. The amount of tar-like by-products can be determined by dissolving and collecting all substances adhering to the reaction tube 4, the exhaust pipe 33, the tar trap 32, etc. in acetone, and measuring the weight of the residue obtained by evaporating the acetone. It was measured.

The tar-like by-products are subjected to component analysis using an infrared spectrophotometer (FT-IR-8200PC, Shimadzu Corp.), and a high-condensed aromatic ring derived from acetylene or a bond between highly condensed aromatic rings Was found to be a substance. In addition, a substance identification test was performed using a mass spectrometer, and it was found that the substance had a high molecular weight and at least a molecular weight of 1,000 or more.

Table 1 summarizes the results of Condition 1 to Condition 3. The electron microscope images of Condition 1 are shown in FIGS. 3 and 4, the electron microscope images of Condition 2 are shown in FIGS. 5 and 6, and the electron microscope images of Condition 3 are shown in FIGS. 7 and 8.

Figure 3 is an electron microscope image of a 10000x carbon nanocoil obtained under condition 1 (reference concentration of 12). Figure 4 is an electron microscope image of a 5,000-fold carbon nanocoil obtained under condition 1 (1/2 of the reference concentration). Both show that carbon nanocoils are growing well. Figure 5 is an electron microscope image of a 10,000 times carbon nanocoil obtained under condition 2 (1/4 of the reference concentration). Figure 6 is an electron microscope image of a 5000-fold carbon nanocoil obtained under condition 2 (1/4 of the reference concentration). As in condition 1, both show that carbon nanocoils grow well.

Figure 7 is an electron microscope image of a 10000x carbon nanocoil obtained under condition 3 (standard concentration 1Z8). Figure 8 is an electron microscope image of a 30,000-fold carbon nanocoil obtained under condition 3 (standard concentration 1Z8). Again, as in condition 1, both show that carbon nanocoils grow well.

As can be seen from the above, the use of the method and apparatus of the present invention allows carbon nanocoils to grow at a high density even when the C ₂ H ₂ concentration is reduced to 1/2, 1Z4 and 1/8 of the reference concentration. Proven to be.

In addition, the amount of tar-like substance produced changes from 0.089 g to 0.025 g to 0.05 lg according to the standard concentration of 1 da 2−1 / 4 → 1/8, and moreover, It turned out to be very small. Observation of the external appearance of the reaction tube 4 also showed that contamination by tar-like substances was extremely small, and that the antifouling performance was far superior to that of the conventional apparatus.

[Comparative Example: Production of carbon nanocoil by conventional equipment]

For comparison with Conventional Example 1 using the apparatus of the present invention, a similar carbon nanocoil production test was performed using a conventional apparatus in which the raw material gas supply pipe 8 was removed, ie, the apparatus shown in FIG. The exact same structure and He and C ₂ H ₂ were used. The difference is that the C ₂ H ₂ concentration was changed.

Condition 4 is the same as the reference concentration, condition 5 is the reference concentration 2 33, and condition 6 is the reference concentration 1-3. These results are summarized in Table 2. The results of condition 4 are shown in FIGS. 9 and 10, the result of condition 5 is shown in FIG. 11 and the result of condition 6 is shown in FIG. 12 as electron microscope images. [Table 2]

FIG. 9 is an electron microscope image of a 1000 × magnification carbon nanocoil obtained under condition 4 (identical to the reference concentration). Figure 10 is obtained under condition 4 (identical to the reference concentration). It is an electron microscope image of a carbon nanocoil of 5000 times. Carbon nanocoils are growing well, and the results of the prior art have been reproduced! /

Fig. 11 is an electron microscope image of a 10,000-fold carbon nanomaterial obtained under condition 5 (2/3 of the reference concentration). Figure 12 is an electron microscope image of a 10,000-fold carbon nanostructure obtained under condition 6 (1/3 of the reference concentration). These images show that the carbon nanocoils are not growing.

From these results, it was found that the conventional method and the conventional apparatus cannot grow carbon nanocoils unless the concentration is about the reference concentration, and carbon nanocoils cannot grow if the concentration is lower than the reference concentration.

In addition, the weight of the tar-like substance produced is extremely high at 0.317 g in Condition 4, and decreases to 0.083 _§ and 0.048 g in Condition 5 and Condition 6. However, the amount of this tar-like substance produced is far greater than the amount of tar-like substance produced under conditions 1 to 3 shown in Table 1. The situation can be understood from the fact that the inner surface of the reaction tube 4 is blackened.

Therefore, it has been demonstrated that the use of the method and apparatus of the present invention can reliably produce carbon nanocoils even when the C ₂ H ₂ concentration is lower than the reference concentration, and that the production amount of tar-like substances can be significantly reduced. It was done.

[Example 2: Carbon nanotube]

FIG. 13 is a schematic configuration diagram when the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention is used for manufacturing carbon nanotubes. This apparatus is a raw material spraying type high-efficiency carbon nanostructure manufacturing apparatus 2 which is exactly the same as in Example 1, except for the catalyst 12, the reaction zone temperature, the temperature of the raw material gas supply pipe, the raw material gas and the carrier gas.

The first difference is that a catalyst obtained by sintering Ni on high-purity r-alumina pellets (99.95% or more) with a sodium content of 0.01% or less was used as the catalyst body 12. It is. The second difference is that the temperature of the reaction zone is maintained at 500 ° C. The third difference is that the temperature of the source gas supply pipe was kept at 250 ° C. The fourth difference is that CH ₄ is used as a source gas and Ar is used as a carrier gas. As described above, in the Ni metal-containing high-purity alumina pellet catalyst described above, carbon nanotubes are generated at a temperature of 400 ° C or higher, and tar-like substances are generated in a temperature range of 250 ° C to 400 ° C. Generated by Therefore, the temperature of the reaction zone was set at 500 ° C, and the temperature of the source gas supply pipe was set at 250 ° C. '

As shown in FIG. 13, carbon nanotubes grew at a high density on the surface of the catalyst 12, and almost no tar-like by-product was observed on the inner surface of the reaction tube 4. The good effect of the method and the device of the present invention using the raw material gas supply pipe 8 and the heater for heating the supply pipe 9 was clearly observed.

The present invention is not limited to the production of carbon nanocoils and carbon nanotubes, but can be used for the production of a wide range of carbon nanostructures such as carbon nanotubes with beads, carbon nanobrushes, and fullerenes. .

[Example 3]

FIG. 14 is a schematic configuration diagram of a raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention in which catalyst powder is used as a catalyst. In FIG. 14, the catalyst 12 of FIG. 1 is composed of the catalyst structure. In Example 3, the catalyst powder 13 flows in the direction of arrow a. When the catalyst powder 13 flows into the reaction zone 10, the catalyst powder 13 is heated to the generation temperature by the reaction zone heater 6, and the source gas is blown from the source gas outlet 8 b onto the catalyst powder 13. The carbon nanostructures 14 grow on the surface of the catalyst powder constituent particles 13a.

The source gas supply pipe 8 is arranged so that the source gas outlet 8 b reaches the reaction region 10, and a heater 9 for the source gas supply pipe is arranged around the source gas supply pipe 8. 8 is heated and held in a temperature range where tar-like substances are not generated.

[Example 4]

FIG. 15 is a schematic configuration diagram in the case where a catalyst powder supply pipe is provided in the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention. In FIG. 15, a catalyst powder supply pipe 7 and a carrier gas supply pipe 31 are provided in addition to the source gas supply pipe 8, and each supply pipe has a heater 9 for a source gas supply pipe, a heater for a catalyst powder supply pipe, A heater for the carrier gas supply pipe is provided. The source gas supply heater is the same as in the other embodiments. No tar-like substance is generated in the entire raw gas supply pipe 8! / Heated and held in the temperature range. Further, since the catalyst powder supply pipe heater 5 heats the catalyst powder supply pipe 7 to the generation temperature, the catalyst powder 13 is supplied to the reaction region 10 at the generation temperature, and the raw material gas is converted into the catalyst gas. By spraying on the powder, the carbon nanostructures begin to grow immediately.

Further, in FIG. 15, a carrier gas supply pipe 31 is also provided, so that the carrier gas can be heated to a predetermined temperature. By heating the carrier gas, the reaction region 10 is maintained at a uniform temperature, and a carbon nanostructure can be stably generated.

[Example 5]

FIG. 16 is a schematic configuration diagram in a case where a mixed gas supply pipe is provided in the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to the present invention. In FIG. 16, the raw material gas and the catalyst powder 13 are mixed and supplied to the reaction zone 10. The mixing ratio between the raw material gas and the catalyst powder 13 is appropriately adjusted. Further, the mixed gas is heated by the mixed gas supply pipe heater 9 so that the raw material gas and the catalyst powder 13 are preheated to the same temperature. When the mixed gas is introduced into the reaction zone 10, the mixed gas is immediately heated to the generation temperature zone, and Nanostructures 14 are generated.

[Example 6]

FIG. 17 is a schematic configuration diagram in a case where a stirrer 17 is attached to the raw material spraying type high efficiency carbon nanostructure manufacturing apparatus 2 according to the present invention. In FIG. 17, a stirrer 17 for stirring the catalyst powder 13 in the reaction region 10 is provided, and the raw material gas is blown onto the stirred catalyst powder 13. The stirrer 17 is provided with a vibrating means using ultrasonic vibration or the like, a rotating means for rotating a rotating plate or a container itself to which the catalyst powder is supplied, and a swinging plate provided in the reaction area. It is composed of rocking means for rocking movement or other known means. Further, an intermittent operation in which a predetermined amount of the catalyst powder 13 is deposited in the carbon nanostructure reaction region 10 provided with the stirring device of Example 6, and then the catalyst powder 13 is stirred, or It can be used in any case of continuous operation in which the catalyst powder 13 is continuously supplied while stirring.

[Example 7] FIG. 18 is a schematic configuration diagram of each gas supply pipe 8 according to the present invention and its gas outlet. (18 A) is a schematic configuration diagram of the nozzle-shaped gas supply pipe 8. A gas outlet 8b is formed at the leading end 8a of each gas supply pipe (a raw material gas supply pipe, a catalyst powder supply pipe, or a carrier gas supply pipe). Supply gas to In (18A), the tip 8a is formed in a tapered shape, and the supplied gas can be more efficiently blown to the reaction region 10.

(18B) is a schematic configuration diagram of a gas supply pipe 8 provided with a gas outlet 8b on the outer periphery. In (18B), a plurality of outlets 8b are provided on the outer periphery of the supply pipe tip 8a, and the raw material gas and Z or the catalyst powder 13 are diffused into the reaction region 10. Therefore, the contact probability between the raw material gas and the catalyst powder 13 increases, so that the carbon nanostructures 14 can be generated with high efficiency. The gas supply pipes used in Examples 1 to 6 are not limited to the shape shown in FIG. 18, and known gas supply pipes having various shapes according to the purpose and gas outlets thereof can be used.

The present invention is not limited to the above-described embodiment, but includes various modifications and design changes within the technical scope without departing from the technical idea of the present invention. Nor.

(Industrial applicability)

According to the first aspect of the present invention, the tar-like by-products are generated by the decomposition and combination of the raw material gas in the process of gradually increasing from the low temperature to the temperature for forming the carbon nanostructure. The inventor's research revealed this. In other words, the subject of this effort is to remove from the reaction process the intermediate temperature region where the source gas decomposes and combines. For this purpose, in the present invention, the raw material gas is kept in a temperature range where the tar-like by-product is not generated (lower temperature, normal temperature or lower temperature than the intermediate temperature range), and the raw material gas is maintained at the intermediate temperature. By jumping into the temperature range where carbon nanostructures are generated at once, it is possible to greatly reduce the generation of tar-like by-products. Moreover, since the raw material gas is directly blown toward the reaction region, the reaction probability between the catalyst body and the raw material gas in the reaction region is increased, and the production yield of carbon nanostructures can be greatly improved. Further, the catalyst body is fixed in the reaction region, and the raw material gas is added to the catalyst body. Or a catalyst may be supplied from the catalyst tank or the like to the reaction area as needed.

According to the second aspect of the present invention, in the present invention, the raw material gas is preheated to a temperature range in which tar-like by-products are not generated, and the preheated raw material gas is jumped over the intermediate temperature to make a carbon nanostructure at once. By raising the temperature to the formation temperature, the generation of tar-like by-products can be significantly reduced. The difference from the first invention is that the raw material gas is preheated. This preheating can increase the reactivity of the raw material gas, thereby increasing the reaction probability of the raw material gas in the catalyst region at an accelerated rate. In addition, since the raw material gas is directly blown toward the reaction region, the reaction probability between the catalyst body and the raw material gas in the reaction region increases, and the generation density and generation efficiency of the carbon nanostructure can be greatly improved. . Further, the catalyst body may be fixed in the reaction area, and a raw material gas may be sprayed on the catalyst body, or the catalyst body may be supplied to the reaction area as needed from a catalyst body tank or the like. .

According to the third aspect of the present invention, since the catalyst body is composed of the catalyst structure, the catalyst body can be installed only in the reaction region, so that the catalyst body and the raw material gas can be efficiently converted. Can be reacted. Further, since the carbon nanostructure is formed on the surface of the catalyst structure, the carbon nanostructure can be collected with higher efficiency than the catalyst structure.

According to the fourth aspect of the present invention, the structure of the catalyst structure can be selected according to the type of the catalyst structure of the carbon nanostructure to be produced. By using a catalyst structure having a layered structure, a lattice structure, a porous structure, or a fibrous structure having a large surface area, a carbon nanostructure can be generated with high efficiency. Further, by using a catalyst structure having a plate-like structure, a carbon nanostructure can be easily recovered.

According to the fifth aspect of the present invention, the catalyst body is formed from catalyst powder, so that the catalyst body can be easily supplied as needed. Further, the carbon nanostructure formed on the surface of the catalyst powder constituent particles can be easily collected by flowing out the catalyst powder.

According to the sixth aspect of the present invention, the catalyst powder is supplied to the reaction region as needed. Thus, the source gas and the catalyst powder can be reacted with high efficiency.

A seventh aspect of the present invention is a method for producing a raw material spraying type high-efficiency carbon nanostructure in which the catalyst powder is supplied from a catalyst powder supply pipe into a space heated to the production temperature range. By supplying the catalyst powder from the catalyst powder supply pipe, a necessary amount can be appropriately supplied to the reaction region. Further, by heating the catalyst powder supply pipe, the catalyst powder heated to the production temperature range can be supplied, and can react with the raw material gas immediately.

According to the eighth aspect of the present invention, the carbon nanostructure can be manufactured with high efficiency by appropriately adjusting the mixing ratio of the raw material gas and the catalyst powder. Furthermore, by heating the mixed gas, the raw material gas and the catalyst powder can be preheated to the same temperature, and when introduced into the reaction zone, the mixed gas is immediately heated to the generation temperature range, and the carbon nanostructure is heated. Products can be manufactured with high efficiency.

According to the ninth aspect of the present invention, the raw material gas can be efficiently brought into contact with the catalyst powder by stirring the catalyst powder, and the carbon nanostructure can be manufactured with high efficiency. it can. Examples of the stirring method include a vibration method using ultrasonic vibration, a rotation method for rotating a rotating plate or a container to which the catalyst powder is supplied, and a swinging plate provided in the reaction region. An oscillating method of moving or other known methods can be used.

According to the tenth aspect of the present invention, for example, the temperature at which tar-like by-products are generated from hydrocarbons used as a raw material gas is from 300 ° C. to 600 ° C., The temperature at which carbon nano-structures are formed from 550 ° C or more, depending on the type of catalyst, is a little more than 550 ° C, and is efficiently between 600 ° C and 1200 ° C. it is conceivable that. Therefore, if the preheating temperature of the raw material gas is controlled to 300 ° C. or lower and the preheated raw material gas is sent to the reaction zone at 600 ° C. or higher at a stretch, the raw material gas becomes a tar-like by-product. Since it does not pass through the production temperature region, no by-products are generated in principle. According to the eleventh embodiment of the present invention, the temperature of the raw material gas is in a temperature range in which tar-like by-products are not generated, so that no tar-like by-products are generated inside the raw material gas supply pipe. In addition, since the source gas is blown directly from the source gas outlet to the catalyst body, the source gas comes into contact with the catalyst with high probability and is efficiently converted into carbon nanostructures. Thus, the generation of tar-like by-products can be sharply reduced. Since much of the raw material gas is consumed in the catalytic reaction, the formation of tar-like substances in the reaction tube is also strongly suppressed.

According to the 12th mode of the present invention, a tar-like product is not generated inside the raw material gas supply pipe in the preheating temperature range, and the preheated raw material gas is directly blown from the raw material gas outlet to the catalyst. Therefore, the preheated raw material gas comes into contact with the catalyst with high probability, and the carbon nanostructure is produced with high efficiency. Therefore, as in the case of the above-described apparatus, much of the raw material gas is consumed in the catalytic reaction, so that the generation of tar-like substances in the reaction tube can be prevented.

According to the thirteenth aspect of the present invention, no tar-like products are generated inside the mixed gas supply pipe in the preheating temperature range. The preheated mixed gas that has flowed into the reaction zone from the mixed gas outlet is instantaneously heated to the generation temperature, and is discharged to the raw material gas and the catalyst body of the mixed gas, so that the preheated mixed gas is directly blown onto the catalyst body. However, the preheated raw material gas comes into contact with the catalyst with high probability, and carbon nanostructures are produced with high efficiency. Therefore, as in the case of the above-described apparatus, much of the raw material gas is consumed in the catalytic reaction, so that the formation of tar-like substances in the reaction tube can be prevented.

According to the fourteenth aspect of the present invention, a required amount of catalyst powder can be supplied by supplying the catalyst to the reaction region through the catalyst supply pipe for supplying the catalyst. Further, by preheating the catalyst body from the preheating device, the catalyst body supplied to the reaction region reaches the generation temperature instantaneously and can react with the raw material powder.

According to the fifteenth aspect of the present invention, the raw material gas can be efficiently brought into contact with the catalyst powder by stirring the catalyst powder, and the carbon nanostructure can be produced with high efficiency. Can be. The stirrer includes a vibrating means using ultrasonic vibration, a rotating means for rotating a rotating plate or a container to which the catalyst powder is supplied, and a swinging plate provided in the reaction region. It can be constituted by a rocking means for performing a moving motion, or other known means. Further, the catalyst may be stirred after a predetermined amount of the catalyst has been deposited in the reaction zone, or the catalyst may be stirred while the supply of the catalyst is continued.

According to the sixteenth aspect of the present invention, if a carbon nanocoil production catalyst is used, Since carbon nanocoils can be selectively produced from hydrogen hydride, the method of the present invention can reduce tallic by-products and simultaneously produce carbon nanocoils with high density and high efficiency. As the carbon nanocoil production catalyst, a metal carbide catalyst, a metal oxide catalyst or a metal catalyst containing a transition metal element can be used. The transition metal element means a transition element shown in the periodic table. Specifically, the transition metal element includes Sc to Cu in the fourth cycle, Y to Ag in the fifth cycle, and La to Au in the sixth cycle. is there. Assuming that an element selected from the above transition metal elements is A, as the metal carbide, AInC, ASnC, AInSnC and the like can be used as a catalyst for producing a carbon nanostructure. Further, as the metal oxide, AIn〇, ASnO, AInSnO, AA13110 or SnO or the like can be used as a catalyst for producing a carbon nanostructure. As the metal-based catalyst, AAl Sn, AC r Sn or AI n Sn can be used. Further, as a suitable metal catalyst, a metal catalyst containing a Fe element as a transition metal element can be used as a catalyst for producing a carbon nanostructure. More specifically, as _{_{_{F e x I n y C z}}} , F e x S n y C z or _{_{_{F e x I n y C z}}} Sn w Fe -based metal carbide catalyst for carbon nanostructure production catalyst, such as The preferred composition ratio of the metal carbide catalyst is Fe ₃ InC. . _5, F e ₃ S nC or _{_{_{F e 3 I ni -. V}}} C 0 5 S n w (0≤ v <1, W≥0) Ru der. Further, as the carbon nanostructure production _{_{catalyst, F e x I n y Sn}} z, F e x A l y Sn z or F e _x C r _y Sn _z can be used F e based metal catalyst such as , A more preferable composition ratio is F e ₃ I n _y S n _z ( _y ≤ 9, _z ≤ 3), F e _x A l _y Sn _z

(y≤l, z≤3) or F e Cr _y Sn _z (y≤1, z≤3). By selecting a catalyst from these metal catalysts according to the purpose, carbon nanostructures can be produced with high efficiency.

According to a seventeenth aspect of the present invention, there is provided a method for producing a high-efficiency carbon nanostructure, wherein the raw material gas contains at least one of acetylene, arylene, ethylene, benzene or toluene, alcohol or methane. These source gases are suitable source gases particularly for producing carbon nanostructures among hydrocarbons, and can mass-produce carbon nanostructures without generating tar-like by-products. . According to an eighteenth aspect of the present invention, the carbon nanostructure is a carbon nanocoil, This is a method for producing a high-efficiency mono-bonano structure by spraying a raw material, which is carbon nanotube, carbon nano twist, carbon nanotube with beads, carbon nano brush or fullerene. By changing the type of the catalyst body or variably adjusting the generation temperature of the reaction zone, a specific carbon nanostructure can be selectively mass-produced.

Claims

The scope of the claims

1. In a method of producing carbon nanostructures from a source gas by catalytic chemical vapor deposition, a tar-like material is placed in a space heated to the temperature at which carbon nanostructures are formed, so as to contact the catalyst body. A method for producing a high-efficiency carbon nanostructure by spraying a raw material, wherein a raw material gas in a temperature range in which by-products are not generated is sprayed to generate a carbon nanostructure.

2. In the method of producing carbon nanostructures from the raw material gas by catalytic chemical vapor deposition, the tar-like secondary material is brought into contact with the catalyst body in a space heated to the temperature range for generating carbon nanostructures. A method for producing carbon nanostructures by spraying a raw material gas preheated to a temperature range in which products are not generated, thereby producing carbon nanostructures.

3. The method for producing a high-efficiency carbon nanostructure according to claim 1 or 2, wherein the catalyst body comprises a catalyst structure.

4. The method according to claim 3, wherein the catalyst structure has at least one of a plate structure, a layer structure, a lattice structure, a porous structure, and a fibrous structure.

5. The method for producing a high-efficiency carbon nanostructure according to claim 1 or 2, wherein the catalyst body is composed of a catalyst powder.

6. The raw material spraying according to claim 5, wherein the catalyst powder is supplied to a reaction zone in a space heated to a carbon nanostructure generation temperature range, and the catalyst powder is heated to the generation temperature range. Method for producing high-efficiency carbon nanostructures.

7. The method according to claim 5, wherein the catalyst powder is supplied from a catalyst powder supply pipe into a space heated to the production temperature range.

8. The method according to claim 5, wherein the raw material gas mixed with the catalyst powder is blown into a space heated to the generation temperature range.

9. The raw material spraying type high efficiency carbon nanostructure according to claim 5, wherein the catalyst powder in the space heated to the generation temperature range is stirred, and the raw material gas is blown onto the catalyst powder. Production method.

10. The method for producing a high-efficiency single-bon nanostructure according to claim 2, wherein the preheating temperature of the raw material gas is set to 300 ° C. or lower.

1 1. In a device that manufactures carbon nanostructures from a raw material gas by catalytic chemical vapor deposition, a heating device that heats the reaction region to the temperature range for generating carbon nanostructures is provided, and the raw material gas is placed in the reaction region. A source gas supply pipe to be introduced is provided, the source gas outlet is arranged in the reaction region, and a source gas in a temperature range where tar-like by-products are not generated is blown from the source gas outlet to the catalyst. High-efficiency carbon nanostructure manufacturing equipment with material spraying.

1 2. In a device that manufactures carbon nanostructures from a raw material gas by catalytic chemical vapor deposition, a heating device that heats the reaction region to the temperature range for generating carbon nanostructures is provided, and the raw material gas is placed in the reaction region. A source gas supply pipe to be introduced is provided, and the source gas outlet is arranged in the reaction area. From a preheating device that preheats the source gas supply pipe to a temperature and a temperature range where a tar-like product is not generated from the source gas. A raw material spraying type high-efficiency carbon nanostructure manufacturing apparatus which is configured and blows a preheated raw material gas from the raw material gas outlet to the catalyst.

1 3. In a device for producing carbon nanostructures from a source gas by catalytic chemical vapor deposition, a heating device that heats the reaction area to the temperature range for generating carbon nanostructures is provided. A mixed gas supply pipe for introducing a mixed gas of the catalyst and the catalyst body is provided, and the mixed gas outlet is arranged in the reaction area, and the mixed gas supply pipe is preheated to a temperature range in which tar-like products are not generated from the mixed gas. A raw material spraying type high-efficiency single-bon nanostructure manufacturing apparatus, characterized in that a preheating apparatus is installed and a preheated mixed gas is blown into a reaction zone.

14. A catalyst supply pipe for supplying a catalyst in the reaction region, a preheating device for preheating the catalyst supply pipe is provided, and the raw material gas is blown onto the preheated catalyst. 13. The raw material spraying type high efficiency carbon nanostructure manufacturing apparatus according to 12.

15. The raw material spraying type high-efficiency carbon nanostructure manufacturing apparatus according to claim 11 or 12, further comprising a stirrer for stirring the catalyst body in the reaction region, wherein the raw material gas is blown to the stirred catalyst medium. .

16. The catalyst according to claim 1, wherein the catalyst is a carbon nanocoil production catalyst. Method for producing high-efficiency carbon nanostructures by spraying raw materials.

17. The method according to claim 1, wherein the raw material gas contains at least one of acetylene, arylene, ethylene, benzene, toluene, alcohol and methane.

18. The raw material spraying type high efficiency carbon nano according to claim 1 or 2, wherein the carbon nano structure is a carbon nano coil, a carbon nanotube, a carbon nano twist, a carbon nanotube with beads, a carbon nano brush or a fullerene. Structure manufacturing method.