JP2003171106A - Method for manufacturing fullerenes and apparatus for manufacturing fullerenes - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing fullerenes suitable for economic mass production. <P>SOLUTION: In the method for manufacturing fullerenes, the source hydrocarbon compound is combusted and/or pyrolyzed. The method features that, after the temperature of the source hydrocarbon compound is controlled to ≥100°C, the source material is introduced into a high temperature zone where the source hydrocarbon compound is combusted and/or pyrolyzed to produce fullerenes. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing fullerenes.

[0002]

2. Description of the Related Art Fullerenes (hereinafter sometimes simply referred to as "fullerene") are a general term for a third carbon allotrope after diamond and graphite, and are represented by C ₆₀ , C ₇₀ , and the like. It is a hollow shell-shaped carbon molecule that is closed by a network of 5- and 6-membered rings. The existence of fullerenes was finally confirmed in 1990, which is a relatively new carbon material, but it was recognized that it has unique physical properties due to its special molecular structure. , Innovative application development is rapidly expanding in a wide range of fields such as the following. (1) Application to ultra-hard materials: Since fullerene is used as a precursor to purify artificial diamond having fine crystal grains, it is expected to be used as a wear-resistant material with added value. (2) Application to pharmaceuticals: Research is progressing as applications such as anti-cancer agents, AIDS / osteoporosis / Alzheimer's therapeutic agents, contrast agents, and stent materials by using C60 derivatives and optical devices. (3) Application to superconducting materials: It was discovered that doping a fullerene thin film with metallic potassium can produce superconducting materials with a high transition temperature of 18K.
It is attracting attention from many fields. (4) Application to semiconductor manufacturing: Utilizing that the resist structure is further strengthened by mixing C ₆₀ with the resist, application to next-generation semiconductor manufacturing is expected.

Among fullerenes having various carbon numbers, CC ₆₀ ,
C ₇₀ and C ₇₀ are relatively easy to synthesize, and therefore, future demand is expected to increase explosively. The currently known methods for producing fullerenes include the following methods. (1) Laser vapor deposition method: A method in which a carbon target placed in a rare gas is irradiated with a pulsed laser of high energy density to synthesize carbon atoms by evaporation. A quartz tube through which a noble gas flows is placed in an electric furnace and a graphite sample is placed in the quartz tube. When the graphite sample is irradiated with a laser from the upstream side of the gas flow to evaporate it, soot containing fullerenes such as C ₆₀ and C ₇₀ adheres to the inner wall of the cooled quartz tube near the outlet of the electric furnace. The amount of evaporation per shot is small, making it unsuitable for mass production. (2) Resistance heating method: A method in which a graphite rod is electrically heated and sublimated in a vacuum vessel filled with helium gas. Large electric resistance loss in the circuit makes it unsuitable for mass production. (3) Arc discharge method: Two graphite electrodes are lightly contacted in helium gas at several tens of kPa, or arc discharge is caused in a state of being separated by about 1 to 2 mm,
A method of sublimating carbon in the anode. Currently used for mass production on a factory scale. (4) High-frequency induction heating method: Instead of using resistance heating or arc discharge, high-frequency induction causes a eddy current to flow in the raw graphite to heat and evaporate it. (5) Combustion method: A method of incompletely burning a hydrocarbon raw material such as benzene in a mixed gas of an inert gas such as helium and oxygen. 10% of benzene fuel becomes soot
The production efficiency is not good in that it becomes fullerene to a certain extent, but it can be used as a soot (fullerene, etc.) to be duplicated for liquid fuels, etc., and the production equipment is simple. Attention has been paid. (6) Naphthalene thermal decomposition method: About 1000 naphthalene
Method of pyrolyzing at ℃. As described above, various methods for synthesizing fullerenes have been proposed so far, but none of the methods has been established so far for inexpensively mass-producing fullerenes.

Of these methods, the combustion method is considered to be one of the cheapest and most efficient manufacturing methods. For example, Japanese Patent Publication No. 6-507879 discloses a method for producing fullerenes by burning a carbon-containing material in a flame and collecting a condensate in a reactor for producing fullerenes. In such a combustion method, fullerenes are produced as a mixture together with soot-like substances, so that the mixture is usually purified to produce fullerenes. Therefore, how to increase the content of fullerenes in a mixture containing this soot-like substance has become a major issue.

For example, Japanese Patent Laid-Open Publication No. 6-507879 mentioned above raises the flame temperature in order to improve the yield of fullerenes, and as a means thereof, further supplies energy to the flame from an external energy source. Etc. are described. In this case, preferable energy sources include electric resistance heating of the input flow, microwave heating, discharge heating and countercurrent heating.

In general, fullerenes are produced under reduced pressure, and a diluent may be introduced into a high temperature zone of a reaction furnace in some cases. It is known that the degree of reduced pressure and the concentration of the diluent affect the yield of the fullerene. In Japanese Patent Publication No. 6-507879, which is described above,
The use of pure oxygen as the oxidant and argon as the diluent for the combustion reaction is described. This is considered to have the effect of increasing the yield of fullerenes.

[0007]

As described above, in order to efficiently produce fullerenes, heat energy is applied to the raw material hydrocarbon compound and the fullerene is produced under high temperature and high vacuum under the production conditions of diluting gas. Doing is an important point. Further, the yield of fullerene in the combustion method is generally higher as the combustion flame temperature is higher, and higher as the dilution rate in the reaction furnace is higher.

In the conventional method for producing fullerenes by the combustion method, high thermal energy required for producing fullerenes can be obtained relatively easily, but when combustion is performed, combustion exhaust gas is generated at the same time as heat, and this produces fullerenes. There is a problem that the condition of "under high vacuum and in diluent gas" is obstructed in the high temperature zone which is the region. Further, since the generated combustion gas usually forms a flow as a combustion gas flow, the problem that the higher the combustion flame temperature, the stronger the turbulence of the air flow condition in the high temperature region where fullerenes are generated. There was also. This is because it is generally said that fullerenes are efficiently produced in a laminar flow and under an extremely dilute air flow condition, so that it is preferable that the fullerene is a dilute and laminar atmosphere in a high temperature zone. Is.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a method for producing a fullerene in a large amount at a low cost and easily.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention have studied various methods for producing fullerene in a large amount at low cost and stably by a combustion method. As a result, the temperature of the hydrocarbon compound that becomes the raw material for fullerene is set to a certain temperature or higher, and a part of the thermal energy required to generate fullerene is given to the raw material hydrocarbon compound before the introduction into the reactor, so that the fullerene It was found that the fullerene can be stably produced in the high temperature range where the silane is produced.

Further, as a heat source in a high temperature zone for producing a fullerene by burning and / or thermally decomposing a raw material hydrocarbon compound, the oxygen-containing gas and the fuel are burned and the combustion gas stream is not used as it is. It was also found that a large amount of fullerenes can be stably produced by utilizing the thermal energy of the combustion flow via a heat exchanger. As a result, not only the proportion of heat energy obtained from the combustion reaction of the raw material hydrocarbons can be reduced, but also the flow rate of the combustion gas formed by the combustion reaction can be suppressed, and fullerenes can be efficiently produced. .

That is, the gist of the present invention is a method for producing fullerenes by burning and / or thermally decomposing a raw hydrocarbon compound, wherein the raw hydrocarbon compound is burned after the raw hydrocarbon compound temperature is set to 100 ° C. or higher. And / or introducing into a high temperature zone where fullerenes are produced by thermal decomposition. Another aspect of the present invention is to provide a combustion gas flow forming furnace for combusting an oxygen-containing gas and a fuel to form a combustion gas flow, a heat exchanger for obtaining heat energy from the combustion gas flow, and the heat exchange. And a reactor for forming a high temperature zone for obtaining fullerenes by burning and / or thermally decomposing a raw material hydrocarbon compound using a reactor as a heat source.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The manufacturing method and manufacturing apparatus of the present invention will be specifically described below with reference to the drawings. Figure 1
FIG. 1 is an overall schematic cross-sectional view of an example of a fullerene manufacturing apparatus according to the present invention. However, the present invention is not limited to FIG. First, the manufacturing apparatus of the present invention will be described.
An example of the fullerene production apparatus of the present invention shown in FIG.
A reaction furnace including a first reaction zone (1) for combusting an oxygen-containing gas and a fuel to form a combustion gas stream, and a raw hydrocarbon compound are combusted and / or thermally decomposed to produce fullerenes. And a reaction furnace including a second reaction zone (2). The first reaction zone (1) and the second reaction zone (2) are configured as independent reactors, respectively, and the combustion gas flow formed in the first reaction zone (1) directly flows into the second reaction zone. It has a structure that does not flow into (2). Each of the reactors including these two zones receives heat energy into the second reaction zone via a heat exchanger (3) for extracting heat energy of the fuel gas stream formed in the first reaction zone (1). It has a structure that conveys.

Although not shown, part of the combustion gas flow formed in the first reaction zone (1) may be introduced as part of the heat source in the second reaction zone (2). . In the first reaction zone (1), generally, the fuel is supplied from the fuel supply port (4) and the oxygen-containing gas is supplied from the oxygen-containing gas supply port (5), and these are combusted to generate a high-temperature combustion gas flow. Formed downstream of the reactor. The purpose of the first reaction zone (1) is to obtain a high temperature combustion gas, and the combustion method may be any known method.

A heat exchanger (3) is installed downstream of the first reaction zone (1) and has a structure for preheating the raw material hydrocarbon and the oxygen-containing gas flowing into the second reaction zone (2). There is. A raw material hydrocarbon supply port (6) and an oxygen-containing gas supply port (7) are provided upstream of the second reaction zone (2), and the raw material hydrocarbon compound of fullerene is supplied from the raw material hydrocarbon supply port (6). Is supplied into the furnace from the oxygen-containing gas supply port (7).

These starting hydrocarbon compounds and oxygen-containing gas are preheated by the heat exchanger (3) before being supplied to the second reaction zone. The higher this preheating temperature is, the higher the preheating temperature is, the more the combustion and / or combustion of the raw hydrocarbon compound in the second reaction zone (2).
Alternatively, it is possible to reduce the thermal energy required for the process of producing fullerenes by thermal decomposition. That is, the rate of securing the thermal energy by burning the raw material hydrocarbon compound is lowered, so that the rate of combustion of the raw material hydrocarbon compound can be reduced and the fullerene can be efficiently produced.
The temperature at which preheating is possible differs depending on the material of the heat exchanger (3) and the like, and is about 400 ° C. in the case of a general stainless steel material. If a generally well-known heat-resistant stainless steel such as Hastelloy steel is used, the temperature can be increased to about 500 ° C to 600 ° C. Furthermore, it is possible to preheat to 600 ° C. or higher by using ceramics or the like.

The second reaction zone (2) has a substantially closed structure, and the pressure in the second zone can be kept below atmospheric pressure.
The soot-containing substance containing fullerenes produced in the second reaction zone (2) goes to a separation / purification device (not shown) located further downstream of the second reaction zone (2), where fullerene and Separated into other soot-like substances to produce fullerenes. As the separation / purification device at this time, any conventionally known device can be used. For example, in addition to using a device that separates and purifies by solvent extraction or a chromatographic separation device, a sublimation purification device, that is, a separation and purification device that has a filter for soot-like substances in a high-temperature atmosphere that allows fullerenes to exist in a gaseous state An apparatus for separating and purifying only the fullerenes by passing them through a filter can be used.
In addition, these may be appropriately combined and used.

Next, the manufacturing method of the present invention will be described. The method for producing fullerenes of the present invention is a method for producing fullerenes in which raw material hydrocarbon compounds of fullerenes are burned and / or pyrolyzed, and the raw material hydrocarbon compounds are preheated to 100 ° C. or higher and then the raw material carbonization is performed. It is characterized in that the hydrogen compound is introduced into a high temperature zone where fullerenes are produced by combustion and / or thermal decomposition. The higher the preheating temperature of the raw material hydrocarbon compound, the better if it is 100 ° C. or higher.
The temperature below 400 ° C. is particularly preferable. As the raw material hydrocarbon compound, any conventionally known compound can be used. Specifically, for example, aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, and anthracene, coal-based hydrocarbons such as creosote oil, carboxylic acid oil, ethylene heavy-end oil, FCC oil (fluid catalytic cracking residual oil ) Etc., petroleum heavy oils, acetylene unsaturated hydrocarbons, ethylene hydrocarbons, saturated aliphatic hydrocarbons such as pentane and hexane, etc. Good.

The high temperature zone for producing fullerenes is usually
It is formed in the second reaction zone (2) in FIG. The heat source in this high temperature zone is preferably a combustion gas flow obtained by burning an oxygen-containing gas and a fuel, because it can be stably and inexpensively supplied. Among them, it is preferable to use a heat exchanger that uses the heat energy of this combustion gas flow as a heat source, because it is possible to make the high-temperature zone in which fullerenes are produced leaner, especially in this high-temperature zone. It is preferred not to introduce a gas stream.

The fuel used to form the combustion gas stream is
Fuel gas such as hydrogen, carbon monoxide, natural gas, petroleum gas,
Conventionally known fuels such as petroleum-based liquid fuels such as heavy oil and coal-based liquid fuels such as creosote oil can be used. As the oxygen-containing gas, it is possible to use air, oxygen gas, or a gas in which an incombustible gas such as nitrogen gas is mixed at an arbitrary ratio. Above all, it is preferable to use air for reasons such as easy availability. Also, in particular, oxygen-enriched air enriched with oxygen may be used to raise the temperature of the combustion gas stream. In addition, N in high temperature combustion
Pure oxygen may be used to suppress the generation of Ox.

In the present invention, it is preferable to set the pressure in the high temperature zone for producing fullerenes to less than atmospheric pressure, because fullerenes can be produced efficiently and stably. Specifically, 1 to 500 Torr, especially 10
It is preferably 300 Torr. The temperature in the high temperature zone is at least 1400 ° C. or higher, preferably 1800
It is preferable that the temperature is not less than 0 ° C, more preferably not less than 2000 ° C.

Further, in the present invention, the oxygen-containing gas may be supplied to the second reaction zone (2) forming the high temperature zone where fullerenes are produced. This is because the heat energy required for producing fullerenes, which is insufficient only by preheating the raw material hydrocarbon compound, is obtained by the combustion heat of the raw material itself. As the oxygen-containing gas, pure oxygen gas, air, or a gas in which an incombustible gas such as nitrogen gas is mixed at an arbitrary ratio can be used, but pure oxygen gas is preferable from the viewpoint of fullerene yield. Further, in order to increase the yield of fullerene, it is preferable to dilute the raw material and the oxygen-containing gas with a rare gas or the like. The fuel diluent concentration is
It is substantially in the range of 0 to 40 mol%, and the diluent concentration of the oxygen-containing gas can be arbitrarily adjusted in the range of 0 to 90% mol.

The present invention is suitable for producing any fullerenes, but is particularly useful for producing C ₆₀ and / or C ₇₀ fullerenes.

[0024]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing fullerenes in large quantities at low cost and easily.

[Brief description of drawings]

FIG. 1 is an overall schematic cross-sectional view of an example of a fullerene production apparatus of the present invention.

[Explanation of symbols]

1: First reaction zone 2: Second reaction zone 3: Heat exchanger 4: Fuel supply port 5: Oxygen-containing gas supply port 6: Feedstock hydrocarbon feed port 7: Oxygen-containing gas supply port

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takaharu Yamamoto             1-1 Kurosaki Shiroishi, Hachiman Nishi Ward, Kitakyushu City, Fukuoka Prefecture               Mitsubishi Chemical Co., Ltd. F-term (reference) 4G046 CA02 CB02 CC02 CC03 CC09

Claims (11)

[Claims] 1. A method for producing fullerenes by burning and / or thermally decomposing a raw material hydrocarbon compound, wherein the raw material hydrocarbon compound is combusted and / or thermally decomposed after the temperature of the raw material hydrocarbon compound is 100 ° C. or higher. A method for producing fullerenes, which comprises introducing the fullerene into a high temperature zone where the fullerene is produced. 2. The manufacturing method according to claim 1, wherein the heat source in the high temperature zone is a combustion gas flow obtained by burning an oxygen-containing gas and a fuel. 3. The manufacturing method according to claim 2, wherein the heat source in the high temperature zone is a heat exchanger using the heat energy of the combustion gas flow. 4. The method according to claim 3, wherein substantially no combustion gas flow is introduced into the high temperature zone. 5. The manufacturing method according to claim 1, wherein the pressure in the high temperature zone is less than atmospheric pressure. 6. The manufacturing method according to claim 1, wherein the fullerenes are C ₆₀ and / or C ₇₀ . 7. A combustion gas flow forming furnace for combusting an oxygen-containing gas and a fuel to form a combustion gas flow, a heat exchanger for obtaining heat energy from the combustion gas flow, and the heat exchanger as a heat source. An apparatus for producing fullerenes, comprising a reactor for forming a high-temperature zone in which a raw material hydrocarbon compound is burned and / or thermally decomposed to obtain fullerenes. 8. The production apparatus according to claim 7, wherein the combustion gas flow forming furnace and the reaction furnace for obtaining fullerenes are independent furnaces. 9. The production apparatus according to claim 7 or 8, further comprising a heating device for heating the raw material hydrocarbon compound before introducing it into the reaction furnace. 10. The manufacturing apparatus according to claim 7, wherein the heat source of the heating device is a heat exchanger for obtaining heat energy from the combustion gas flow. 11. The manufacturing apparatus according to claim 7, wherein the reaction furnace has a substantially closed structure such that the pressure inside the furnace is less than atmospheric pressure.