JP2018126705A - Catalyst precursor composition for the production of carbon nanotubes and method for producing the same, and method and device for producing carbon nanotubes using the catalyst precursor composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst precursor composition for the production of carbon nanotubes that can supply, continuously for a long time, a vaporized catalyst raw material containing a metal catalyst as the main component and a promoter as an accessory component, with each of the metal catalyst and the promoter controlled stably in vapor pressure, without mixture of unnecessary compounds for the production of carbon nanotubes, and a method for producing the same; and a method and a device for producing carbon nanotubes using the catalyst precursor composition.SOLUTION: A catalyst precursor composition for the production of carbon nanotubes 11 contains, as solute, an organic transition metal-complex compound for the production of carbon nanotubes 2, and as solvent, a sulfur-containing component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a catalyst precursor composition for producing carbon nanotubes (CNT), a method for producing the same, and a method and an apparatus for producing carbon nanotubes using the catalyst precursor composition.

  Single-walled carbon nanotubes (CNT) have a diameter of 0.6 to several nm, a length of several μm or more, and a very large aspect ratio. Due to such an elongated shape, it is expected to be applied to a power-saving thin TV as a scanning probe needle or an electron emission source. In addition, various applications such as transistors, transparent electrodes, batteries and capacitors have been proposed because of their excellent electrical and electronic characteristics and stability.

  It has been widely practiced to continuously synthesize carbon nanotubes by supplying steam from a metal catalyst source containing metal nanoparticles such as ferrocene and a promoter source such as a sulfur compound into a reaction furnace. The present invention makes it easier and more stable.

  In the production of carbon nanotubes, metal nanoparticles are extremely important as a template for determining the diameter of carbon nanotubes and as a catalyst for suppressing side reactions and promoting the production of carbon nanotubes. Various catalysts have been developed. Among them, a metal catalyst of a metal containing iron, particularly a transition metal catalyst obtained by adding a sulfur component as a co-catalyst is known to have high activity.

  In the floating catalyst CVD method and the flame synthesis method, these vaporized catalyst raw materials are continuously supplied to the reaction field in the reaction furnace to continuously synthesize carbon nanotubes. Ferrocene is widely used as a source of iron vapor as a catalyst. However, when ferrocene is heated to a melting point or higher, the vapor pressure is too high, so it was normal to supply iron by sublimating solid ferrocene. .

As a source of sulfur vapor, thiophene (C ₄ H ₄ S), carbon disulfide (CS ₂ ), sulfur (S), etc. are used. Among them, sulfur is low in toxicity and easy to handle. Sulfur was usually supplied by sublimation separately from a metal catalyst source such as ferrocene.

  Thus, ferrocene and sulfur are respectively a catalyst precursor compound as a typical metal catalyst (Fe) source and a co-catalyst precursor compound as a sulfur source, but are solid at room temperature and normal pressure and continuously in a solid state. In the case of supplying to the evaporator, it is usually considered to be sent to the evaporator with a screw feeder or the like.

  On the other hand, a method is known in which ferrocene and sulfur are dissolved in an organic solvent or the like to form a solution, and vaporization supply by bubbling of an inert gas, atomization supply, or evaporation supply is performed. For example, Patent Document 1 discloses that a raw material mixture obtained by mixing 0.4 g of ferrocene, 0.4 g of thiophene and 1.0 g of a nonionic surfactant in 100 g of toluene and spraying the mixture on a reaction field is disclosed. Yes. Patent Document 2 discloses that 0.49 kg of ferrocene and 0.01 kg of sulfur are dissolved in 13.5 kg of benzene, and a raw material solution is prepared and sprayed on a reaction field.

Japanese Patent No. 5046078 JP 2014-177722 A

  When a metal catalyst source such as ferrocene is supplied into the reactor in the gas phase by sublimation as in the prior art, the solid ferrocene powder gradually sinters and changes its surface area, so there is a problem that the supply of ferrocene vapor is not stable. It was. The same problem occurs when solid sulfur powder as a promoter source is supplied into the reactor in the gas phase by sublimation.

  In Patent Documents 1 and 2, the metal catalyst source and the promoter source are dissolved in an organic solvent to form a solution. However, in this case, the amount of the organic solvent is larger than that of the metal catalyst source and the cocatalyst source. Furthermore, many organic solvents that are liquid at room temperature have a higher vapor pressure than metal catalyst sources and promoter sources that are solid at room temperature. Even if the catalyst raw material and the carbon raw material are to be controlled independently and highly, since the organic solvent more than the catalyst raw material is mixed in the apparatus and the organic solvent vapor acts as a carbon source, the independent control is difficult.

  A solution in which a large amount of a metal catalyst source is dissolved in a high boiling point solvent and a solution in which a promoter source is dissolved may be prepared, and the metal catalyst and the promoter may be vaporized by bubbling and supplied to the reactor. It's not impossible. However, when a high-boiling solvent is used, there is a limit to the amount and rate of dissolution, and there is a problem that the supply amount of the metal catalyst source is not stable. In addition, if there are foreign elements other than the elements constituting the hydrocarbon, there is a high possibility that things other than CNT will be mixed into the composite.

  The present invention has been made in view of such circumstances. The vapor pressure of each of the metal catalyst and the cocatalyst is stably controlled to vaporize containing the metal catalyst as a main component and the cocatalyst as a subcomponent. A catalyst precursor composition for producing carbon nanotubes, which can be continuously supplied for a long time without mixing a compound unnecessary for the production of carbon nanotubes, and a production method thereof, and the catalyst precursor composition are used. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus for carbon nanotubes.

  In order to solve this problem, the present invention provides a catalyst precursor composition for producing carbon nanotubes containing an organic transition metal complex compound as a solute and a sulfur-containing component as a solvent.

  The catalyst precursor composition contains a total of 0.1 to 10% by weight of transition metals with respect to elemental sulfur, the boiling point of the sulfur-containing component is 50 ° C. or more and 1000 ° C. or less at 1 atm, and the sulfur-containing component is sulfur. It is contained in an amount of 10% by mass or more as an element and can be made liquid in any range of 0 ° C to 200 ° C.

  The transition metal may be at least one selected from Fe, Ni, Co, Y, Mo, and La.

  The catalyst precursor composition contains at least one organic transition metal complex compound containing a metal selected from Fe, Ni, Co, Y, Mo or La, and / or a plurality of metals in the metal It may contain at least one organic transition metal complex compound.

  The organic transition metal complex compound is at least one selected from ferrocene, 1,1-dimethylferrocene, pentamethyl ferrocene, acetyl ferrocene, benzoyl ferrocene, cyclopentadienyl iron carbonyl dimer, cobalt cene, nickel ferrocene and tetracarbonyl nickel. be able to.

  The sulfur-containing component is at least one selected from sulfur, thiophene, methylthiophene, ethylthiophene, hexylthiophene, benzothiophene, dibenzothiophene, tetrahydrothiophene, sulfolane, tetramethylene sulfoxide, an alkylthiol having 3 or more carbon atoms, and thiophenol. can do.

  In the present invention, the method for producing a catalyst precursor composition for producing carbon nanotubes may include a step of dissolving an organic transition metal complex compound in a molten sulfur-containing compound.

  The present invention provides a method for producing a carbon nanotube, a step of vaporizing a catalyst precursor composition, a step of supplying the vaporized organic transition metal complex compound and the vaporized sulfur-containing component into a reaction furnace, and a carbon source gas. And supplying the gas into the reaction furnace.

  The step of vaporizing may be a step of bubbling and vaporizing the catalyst precursor composition at any temperature in the range of 0 to 400 ° C.

  The present invention provides a carbon nanotube production apparatus comprising: a means for vaporizing a catalyst precursor composition; a means for supplying the vaporized organic transition metal complex compound and the vaporized sulfur-containing component into a reaction furnace; and a carbon source gas. And a means for supplying the gas into the reaction furnace.

  According to the catalyst precursor composition of the present invention, the catalyst precursor compound as the metal catalyst source is dissolved in the sulfur-containing component as the co-catalyst source to be introduced into the reaction furnace, so that the metal catalyst and The cocatalyst can be supplied stably for a long time.

  The method for producing the catalyst precursor composition is constituted by a simple method in which a catalyst precursor compound as a metal catalyst source is dissolved in a molten sulfur-containing component as a promoter source.

  According to the carbon nanotube production method using the catalyst precursor composition, the catalyst raw material can be stably supplied continuously to the reaction furnace, and high controllability and high reproducibility of the production of carbon nanotubes can be realized. it can.

It is the schematic of the manufacturing apparatus of the carbon nanotube as an Example using the catalyst precursor composition of this invention. 2 is a schematic view of a carbon nanotube production apparatus of Comparative Example 1. FIG. It is the schematic of a catalyst raw material supply part same as the above. It is the schematic of a co-catalyst supply part same as the above. It is the graph which compared the film | membrane weight of the Example and the comparative example 1 as a parameter | index. The above is a graph comparing the bubbling method and the conventional sublimation method using Fe / C as an index. The above is a graph comparing the bubbling method and the conventional sublimation method using I _D / I _G as an index. FIG. 6 is a graph comparing the bubbling method and the conventional sublimation method using the Fe supply amount as an index. FIG. 6 is a graph comparing the bubbling method with the conventional sublimation method using the amount of C synthesis as an index. 5 is a schematic view of a carbon nanotube production apparatus of Comparative Example 2. FIG.

  The present invention is a catalyst raw material suitable for continuously supplying a catalyst for producing carbon nanotubes. The catalyst raw material as the present embodiment is a catalyst precursor composition containing an organic transition metal complex compound for producing carbon nanotubes as a solute and a sulfur-containing component as a solvent. The organic transition metal complex compound is usually used as a metal catalyst source, and the sulfur-containing component is used as a promoter source.

  The catalyst precursor composition is used as a solution dissolved in the solvent using a promoter precursor compound as a promoter raw material as a solvent and a catalyst precursor compound as a catalyst raw material as a solute.

  The catalyst precursor composition is used as a liquid at the time of use. For example, the catalyst precursor composition can be stored and stored as a solid at a temperature lower than the melting point of the catalyst precursor composition and used as a liquid at the time of use.

  The catalyst precursor composition preferably contains a transition metal as a catalyst component in a total amount of 0.1 to 10% by weight with respect to elemental sulfur. As the transition metal, for example, at least one selected from Fe, Ni, Co, Y, Mo, and La can be used. These transition metals are preferably contained as organic transition metal complexes. As the organic transition metal complex compound, for example, at least one of organic transition metal complex compounds containing a metal selected from Fe, Ni, Co, Y, Mo or La, and / or a plurality of metals in the metal At least one organic transition metal complex compound containing The organic transition metal complex compound is, for example, at least selected from ferrocene, 1,1-dimethylferrocene, pentamethyl ferrocene, acetyl ferrocene, benzoyl ferrocene, cyclopentadienyl iron carbonyl dimer, cobalt cene, nickel ferrocene and tetracarbonyl nickel. One can be used. Among these, a particularly preferable transition metal is Fe, and a particularly preferable organic transition metal complex compound is ferrocene.

  Examples of the sulfur-containing component include sulfur, thiophene, methylthiophene, ethylthiophene, hexylthiophene, benzothiophene, dibenzothiophene, tetrahydrothiophene, sulfolane, tetramethylene sulfoxide, alkylthiols having 3 or more carbon atoms, or thiophenol. At least one can be used. The boiling point of the sulfur-containing component is preferably 50 ° C. or higher and 1000 ° C. or lower at 1 atmosphere. The catalyst precursor composition preferably contains 10% by mass or more of a sulfur-containing component as a sulfur element. Sulfur reduces the surface energy of the iron particles and has the effect of stably forming small catalyst particles. In addition, it is expected that carbon precipitation from iron catalyst particles is promoted by making an eutectic of iron sulfide (FeS).

  Sulfur has a low melting point, a low vapor pressure, and is nonpolar. In contrast, ferrocene has a high melting point and is easily soluble in nonpolar solvents at high vapor pressure. Therefore, according to a solution in which ferrocene is dissolved in a sulfur melt, a wide range of 115 to 175 ° C. is caused by bubbling of inert gas. A vaporized catalyst raw material containing ferrocene as a main component and sulfur as a subcomponent can be stably and continuously supplied.

  The solution preferably contains, for example, only components of a metal catalyst source and a promoter source. In the case of a solution using ferrocene and sulfur, the weight ratio of iron and sulfur in the solution can be appropriately set, and is preferably about Fe: S = 1: 60, for example. Further, the catalyst precursor composition of the present embodiment may contain a small amount of a solvent for the purpose of lowering the melting point. As the solvent, in order to reduce the amount of solvent mixed in the apparatus, a solvent having a boiling point of 150 ° C. or higher is preferable, and a nonvolatile ionic liquid is more preferable.

  In addition, the catalyst precursor composition of this Embodiment is a liquid in the range in any one of 0 degreeC-200 degreeC. The catalyst precursor composition can be produced, for example, by dissolving an organic transition metal complex compound in a molten sulfur-containing compound. In addition, a method for producing a carbon nanotube using the catalyst precursor composition includes a step of vaporizing the catalyst precursor composition, a vaporized catalyst or catalyst precursor, and a cocatalyst or cocatalyst precursor supplied into the reaction furnace. It can be applied to all carbon nanotube production methods using metal catalysts, including physical vapor deposition (PVD), chemical vapor deposition (CVD), and flame synthesis. It can be used to produce catalyst particles suspended in the catalyst or catalyst particles supported on a support. Furthermore, the carbon nanotube production apparatus using the catalyst precursor composition supplies the means for vaporizing the catalyst precursor composition, the vaporized catalyst or catalyst precursor, and the cocatalyst or cocatalyst precursor into the reaction furnace. Means. An example of a specific configuration of the manufacturing apparatus will be described in detail in Examples.

  As an example of a method of vaporizing the catalyst precursor composition and supplying it to the carbon nanotube production apparatus, there is a method of supplying an inert gas such as argon gas to the catalyst precursor composition and bubbling. There is also a method in which the catalyst precursor composition is sent to an evaporator at about 200 ° C. or higher with a syringe pump or the like, and all the liquid is evaporated and supplied. In addition, there is a method in which the catalyst precursor composition is sprayed in the form of a mist and atomized and supplied into the reaction furnace accompanied by argon gas or the like. Examples of the atomizing method include a two-fluid nozzle, electrostatic atomization, and ultrasonic atomization.

  All documents mentioned herein are hereby incorporated by reference in their entirety. The examples described herein are illustrative of embodiments of the invention and should not be construed as limiting the scope of the invention.

(Configuration and manufacturing conditions of the manufacturing apparatus of the example)
Carbon nanotubes were produced using the carbon nanotube production apparatus 1 by flame synthesis shown in FIG. The manufacturing apparatus 1 includes a chamber 3 in which the carbon nanotubes 2 are synthesized, three different tubes, a first tube 4, a second tube 5 and a third tube 6 connected to the chamber 3, and a chamber. 3 is provided.

  The chamber 3 is formed of a cylindrical container made of quartz glass. In the reaction region in the chamber 3, the carbon nanotube 2 is grown.

  The chamber 3 has a reduced diameter portion 32 having a reduced cylindrical cross section slightly below the third outlet 52 where the gas in the third pipe 6 flows out toward the inside of the chamber 3. Reference numeral 26 denotes a first chamber bottom at a portion where the diameter reduction starts, and reference numeral 30 denotes a second chamber bottom which becomes the bottom of the reduced diameter chamber 3.

The first tube 4 is connected to the second chamber bottom 30 of the reduced diameter chamber 3 and constitutes a burner for the premixed flame 12. Therefore, the first pipe outlet 50 of the burner as the first pipe 4 is provided in the reduced diameter portion 32 of the reduced diameter chamber 3, and the premixed flame 12 is preferably disposed in the reduced diameter of the chamber 3. It is formed in the reduced diameter portion 32. The first pipe 4 was supplied with ethylene (C ₂ H ₄ ) gas as a fuel gas together with oxygen (O ₂ ) gas and argon (Ar) gas as an oxidizing gas. Further, the catalyst precursor composition 11 according to the present invention was vaporized by bubbling and supplied to the gas supply path 4 a containing the catalyst raw material to the first pipe 4.

As a catalyst precursor composition 11, a ferrocene (Fe (C ₅ H ₅ ) ₂ ) catalyst precursor compound as a metal catalyst source is used as a solute, and a sulfur melt obtained by heating sulfur as a promoter source to a melting point or higher. The dissolved solution was used. The weight ratio of iron and sulfur was Fe: S = 1: 60. Bubbling was performed by supplying argon gas to the solution. This argon gas for bubbling is expressed as Ar (Fe & S).

Thus, the gas containing the catalyst raw material passes through the gas supply path 4a and is premixed from the first pipe 4 into the reaction furnace of the chamber 3 with the gas containing the vaporized catalyst raw material, ferrocene, and the subcomponent sulfur. It was supplied as a gas. Further, argon (Ar) gas was also supplied to the first tube 4 together with 40% O ₂ / Ar as a premixed gas. When the premixed gas containing the vaporized catalyst precursor composition 11 passes through the premixed flame 12, the catalyst precursor composition 11 as the catalyst and the promoter material is decomposed. Here, the main component means a component having the highest content in the vaporized catalyst raw material. A subcomponent means components other than a main component.

Similarly to the first tube 4, the second tube 5 is connected to the second chamber bottom 30 of the reduced diameter chamber 3. The second pipe 5 was supplied with ethylene (C ₂ H ₄ ) gas as a carbon source gas together with argon (Ar) gas. This carbon source gas is supplied from the second pipe outlet 51 into the reduced diameter portion 32 of the chamber 3. Then, the carbon source gas and the argon gas are mixed with the catalyst precursor composition 11 decomposed by the premixed flame 12 at the end of the first tube 4 to nucleate the catalyst particles 15 and the carbon nanotubes 2.

The third tube 6 is provided on the outer periphery of the chamber 3 so as to cover the chamber side 27 of the chamber 3. The third pipe 6 was supplied with methane (CH ₄ ) gas as a carbon source gas together with argon gas. The carbon source gas is mixed with the catalyst particles 15 and the nucleated carbon nanotubes 2 to grow the carbon nanotubes 2. The carbon source gas flows from the upper side to the lower side of the chamber 3 and is supplied into the chamber 3 in the horizontal direction from a third pipe outlet 52 provided in the chamber side portion 27. The third tube outlet 52 was provided slightly above the first chamber bottom 26 of the chamber 3.

  With the configuration described above, the first pipe outlet 50, the second pipe outlet 51, and the third pipe outlet 52 allow the gas flowing out from the first pipe 4 to flow out from the second pipe 5. It is installed so that the gas flowing out from the third pipe 6 joins after the joining with the gas.

  As the heat retaining means 7, a heating furnace 33 was provided on the outer periphery of the chamber 3. The heating furnace 33 was provided on the outer periphery of the third pipe 6 and used an electric furnace for heating by flowing a current through the nichrome wire, and the temperature was controlled. This heating furnace 33 manages the temperature of the reaction region 8 in the chamber 3 to maintain the growth temperature of the carbon nanotubes 2 and increase the growth time. Further, the carbon source gas flowing in the third pipe 6 was preheated by the heating furnace 33, and the carbon source gas 16 was supplied into the chamber 3 after this preheating.

  The flow rate of the gas flowing through the first tube 4, the second tube 5 and the third tube 6 was controlled by a mass flow controller (not shown).

  As a burner extending from the first tube 4 into the chamber 3, a quartz tube or a stainless tube having an inner diameter of 1 mm and 2 mm was used. The height of the burner was set so that the tip of the burner was lower than the first chamber bottom 26.

  The carbon nanotubes 2 synthesized in the reaction region 8 were collected by a collecting means (not shown) using a membrane filter provided downstream of the chamber upper portion 25.

Table 1 shows the gas types and gas flow rates supplied to the first pipe 4, the second pipe 5, and the third pipe 6. In the description in the table, for example, the Ar gas type and the gas flow rate described as “various (0-300)” means that Ar gas was supplied within the range of 0 to 300 sccm. The same applies to the following tables. In addition, 1 sccm is a flow rate in which a gas having a volume of 1 cm ³ flows in one second in a standard state (0 ° C., 100 kPa), and at a temperature T (° C.) and a pressure P (kPa), 100 (T + 273.15) / (P ′ 273.15) The volumetric flow rate is cm ³ / s.

  Table 2 shows the temperature conditions during the production of the carbon nanotubes. In the table, "Furnace" is the temperature condition of the heating furnace 33, "Ferrocene + Sulfur" is the temperature condition of the solution of ferrocene and sulfur, and "Burner" is immediately after the bubbler where the catalyst and co-catalyst are set (backstream) To the premixed flame 12 are shown. A preferable temperature range of the heating furnace 33 is 800 to 1400 ° C. At low temperatures, it is easy to suppress soot formation, and at high temperatures, the production rate and crystallinity of carbon nanotubes can be increased. More preferably, it is 900-1300 degreeC, The production | generation speed | rate and crystallinity of a carbon nanotube can be improved, suppressing the production | generation of soot. The temperature of the vaporization part of the catalyst precursor composition may be a temperature at which the vaporization part of the catalyst precursor composition does not thermally decompose, and is preferably 0 to 400 ° C. When bubbling is used for vaporizing the catalyst precursor composition, the catalyst precursor composition only needs to be liquid, and 0 to 200 ° C is more preferable. In this example, the catalyst precursor composition comprising ferrocene and sulfur was vaporized by bubbling, but bubbling was performed at 120 to 140 ° C. in order to keep the vapor pressure of ferrocene and sulfur appropriately. The piping from immediately after the bubbler in which the catalyst and the cocatalyst were set (rear stream) to the premixed flame 12 was set to a temperature range of 125 to 150 ° C. in order to prevent precipitation of ferrocene and sulfur in the piping. In addition, when increasing the carrier gas flow rate to the bubbler, it is preferable to lower the vaporization temperature, and when increasing the carrier gas flow rate, it is preferable to increase the vaporization temperature.

  The production time of carbon nanotubes was 5 minutes or 10 minutes at a time, and production was carried out 41 times.

(Configuration and Manufacturing Conditions of Manufacturing Device of Comparative Example 1)
Carbon nanotubes were produced using the carbon nanotube production apparatus 1 ′ by flame synthesis shown in FIG. The same components as those of the manufacturing apparatus 1 of the embodiment are denoted by the same reference numerals and description thereof is omitted.

  It differs from the chamber 3 in the manufacturing apparatus 1 of the embodiment in that it does not have the reduced diameter portion 32 of FIG.

The first pipe 4 was supplied with ethylene (C ₂ H ₄ ) gas as a fuel gas together with oxygen (O ₂ ) gas and argon (Ar) gas as an oxidizing gas. Further, the solid ferrocene powder was vaporized by sublimation and supplied to the first tube 4.

  FIG. 3 shows a catalyst material supply unit 35 for supplying ferrocene as a catalyst material. The catalyst raw material supply unit 35 directly charges the ferrocene powder 37 into the wall 36 of the catalyst raw material supply unit made of a quartz tube and closes both sides thereof with a catalyst raw material holding material 38 made of quartz cotton. With such a configuration, the supply amount of ferrocene can be controlled by the vapor pressure, that is, the temperature, regardless of the amount of ferrocene powder 37 charged. The temperature control of ferrocene was performed by the ribbon heater 40 from the outside with the thermocouple 39 in contact with the outer wall of the quartz tube 36. The catalyst material was sublimated by supplying argon gas to the catalyst material supply unit 35, and the supply amount of the gas containing the catalyst material was controlled by the gas flow rate. The argon gas for supplying the catalyst raw material vapor is expressed as Ar (Fe).

  In the vicinity of the inlet of the catalyst raw material supply unit 35, a bypass line 46 for circulating argon gas is provided near the outlet of the catalyst raw material supply unit 35 without passing through the catalyst raw material supply unit 35. During the temperature increase and the temperature decrease, the gas containing the catalyst raw material is allowed to pass through the bypass line 46 so that the excess catalyst raw material is not supplied to the first pipe 4. By doing so, the amount of impurity Fe contained in the carbon nanotubes 2 collected after the synthesis was reduced.

The second pipe 5 was supplied with ethylene (C ₂ H ₄ ) gas as a carbon source gas together with argon (Ar) gas. Further, solid sulfur powder was vaporized by sublimation and supplied to the second pipe 5.

  FIG. 4 shows a cocatalyst supply unit 41 for supplying sulfur as the cocatalyst 9. The cocatalyst supply unit 41 has a structure in which a cocatalyst holding material 42 made of quartz cotton is arranged on both sides of the cocatalyst powder 55 in the wall 54 of the cocatalyst supply unit made of a quartz tube. As a sulfur source, sulfur powder was used. The temperature control of sulfur was performed by the ribbon heater 60 from outside the thermocouple 59 in contact with the outer wall of the quartz tube 54. The co-catalyst raw material was sublimated by supplying argon gas to the co-catalyst supply unit 41, and the supply amount of gas containing the co-catalyst was controlled by the gas flow rate. This argon gas for supplying the cocatalyst vapor is expressed as Ar (S).

  In the vicinity of the outlet of the cocatalyst supply unit 41, a bypass line 47 for circulating argon gas was provided in the vicinity of the outlet of the catalyst raw material supply unit 41 without passing through the cocatalyst supply unit 41. During the temperature increase and the temperature decrease, the gas containing the cocatalyst passes through the bypass line 47 so that excess cocatalyst is not supplied to the first pipe 4. By doing so, the amount of impurities S contained in the carbon nanotubes 2 collected after synthesis was reduced.

  The third pipe 6 was supplied with methane as a carbon source gas together with argon. The carbon source gas is mixed with the catalyst particles 15 to grow the carbon nanotubes 2. The carbon source gas 16 flows from the upper side to the lower side of the chamber 3 and is supplied into the chamber 3 in a horizontal direction from a third pipe outlet 52 provided in the chamber side portion 27. The third tube outlet 52 was provided in the upper part of the first chamber bottom 26 of the chamber 3.

  Table 3 shows the gas types and gas flow rates supplied to the first pipe 4, the second pipe 5, and the third pipe 6. Unlike the example, sulfur as a cocatalyst was supplied from the second pipe 5.

  Table 4 shows the temperature conditions during the production of the carbon nanotubes. In the table, “Furnace” is the temperature condition of the heating furnace 33, “Ferrocene” is the temperature condition of the ferrocene powder, “Sulfur” is the temperature condition of sulfur, “Burner” is immediately after the place where the catalyst and the promoter are set ( The temperature conditions of the piping from the downstream) to the premixed flame 12 are shown.

  The production time of carbon nanotubes was 10 minutes per time, and 64 times of production were performed.

(Statistical analysis)
In evaluating the film weight, Fe supply amount, and C synthesis amount in the bubbling method of the present invention, numerical values per 10 minutes were obtained and used for statistical analysis.
For statistical analysis, statistical analysis software EZR (http://www.jichi.ac.jp/saitama-sct/SaitamaHP.files/statmed.html) is used. (CV value), the F test method is used for the significance test for variance, the Mann-Whitney U test method, which is a nonparametric test method, is used for the significance test for the mean value, and a p value of 0.05 is significant. Evaluated as a standard.

(Evaluation results of Examples and Comparative Example 1)
In Example 1 and Comparative Example 1 using the sublimation method as a conventional method, it was confirmed by SEM analysis and Raman spectroscopic analysis that single-walled carbon nanotubes were produced in all samples. The produced carbon nanotubes 2 are collected in the form of a film on the membrane filter of the collecting means. Hereinafter, the results of comparison between Example and Comparative Example 1 using the film weight, Fe / C, _ID / _IG , Fe supply amount, and C synthesis amount as indices will be described.

<Membrane weight>
As a result of statistical analysis of the production sample with the total weight of carbon nanotubes produced in one production as the membrane weight (mg), the average membrane weight of the example is 4.47 mg, the standard deviation σ is 1.46 mg, and the coefficient of variation is It was 0.326. The average film weight of Comparative Example 1 was 4.96 mg, the standard deviation σ was 2.16 mg, and the coefficient of variation was 0.436. FIG. 5 is a graph showing the average film weight and standard deviation. In the figure, “Bubbling method” is an example, and “Sublimation method” is Comparative Example 1. The same applies to the following figures and tables.

Table 5 shows the coefficient of variation (CV value) of the membrane weight, statistical analysis results of F test and Mann-Whitney U test. The items of Fe / C, _ID / _IG , Fe supply amount and C synthesis amount in the table will be described later.

  The average film weight was not significantly different between the average values of the example and the comparative example 1, but both the standard deviation σ and the coefficient of variation were smaller in the example. There was a significant difference in the variance between the two groups. Therefore, it can be seen that the production amount of carbon nanotubes is more stable in Example than in Comparative Example 1.

<Fe / C>
Statistical analysis of the production sample was performed and evaluated for Fe / C (wt% / wt%) of the carbon nanotube produced in one production. Fe / C is a value obtained by EDS analysis and is an index indicating the impurity content. It shows that the purity of a carbon nanotube is so high that the value of Fe / C is small. The average value of the examples was 0.864, the standard deviation σ was 0.612, and the coefficient of variation was 0.709. The average value of Comparative Example 1 was 4.01, the standard deviation σ was 4.86, and the coefficient of variation was 1.21. FIG. 6 is a graph showing average values and standard deviations.

  The average value of Fe / C is smaller in the Example than in Comparative Example 1, and it can be seen that the purity of the carbon nanotube is significantly higher in the Example. Both the standard deviation σ and the variation coefficient are smaller in the example. Significant differences were observed for the F test and the Mann-Whitney U test. Therefore, it can be seen that carbon nanotubes having higher purity than those of Comparative Example 1 can be produced stably in the Examples.

< _ID / _IG >
Statistical analysis of the production samples was performed to evaluate I _D / I _G of the carbon nanotubes produced in one production. I _D / I _G is a value obtained by Raman spectroscopic analysis and is an index indicating the crystallinity of the carbon nanotube. In the Raman spectrum, the peak appearing in the vicinity of 1590 cm ⁻¹ is called G-band and is derived from the in-plane stretching vibration of the carbon atom having a six-membered ring structure. A peak appearing near 1350 cm ^-1 is called D-band, and it tends to appear if there is a defect in the six-membered ring structure. The relative carbon nanotube quality can be evaluated by the peak intensity ratio I _D / I _G of D-band to G-band, and the smaller the I _D / I _G value, the higher the crystallinity of the carbon nanotube It can be said. Raman spectroscopic analysis was performed at an excitation wavelength of 488 nm. In the examples, the average value was 0.025, the standard deviation σ was 0.016, and the coefficient of variation was 0.653. The average value of Comparative Example 1 was 0.141, the standard deviation σ was 0.223, and the coefficient of variation was 1.596. FIG. 7 is a graph showing average values and standard deviations.

The average value of I _D / I _G is significantly smaller in the Examples than in Comparative Example 1, and it can be seen that the Examples can produce carbon nanotubes with higher crystallinity and higher quality. Both the standard deviation σ and the variation coefficient are smaller in the example. There was also a significant difference in the variance between the two groups. Therefore, it can be seen that high quality carbon nanotubes can be stably produced in the example as compared with Comparative Example 1.

<Fe supply amount>
Statistical analysis of the production sample was performed to evaluate the Fe supply amount of the carbon nanotube produced in one production. The Fe supply amount is the content of iron in the collected carbon nanotube 2 film based on the film weight and the Fe / C ratio. The average value of the examples was 1.81 mg, the standard deviation σ was 0.937 mg, and the coefficient of variation was 0.519. The average value of Comparative Example 1 was 3.30 mg, the standard deviation σ was 2.20 mg, and the coefficient of variation was 0.664. FIG. 8 is a graph showing average values and standard deviations.

  It can be seen that the average value of the Fe supply amount is significantly smaller in the example than in Comparative Example 1. Both the standard deviation σ and the variation coefficient are smaller in the example. There was also a significant difference between the two groups in terms of variance. Therefore, it can be seen that iron can be supplied more stably in the example than in the first comparative example.

<C synthesis amount>
Statistical analysis of the production sample was performed on the amount of carbon synthesis of carbon nanotubes produced in one production. The amount of C synthesis is the carbon content in the collected carbon nanotube 2 film based on the film weight and Fe / C ratio. The average value of the examples was 2.66 mg, the standard deviation σ was 1.21 mg, and the coefficient of variation was 0.453. The average value of Comparative Example 1 was 1.65 mg, the standard deviation σ was 1.22 mg, and the coefficient of variation was 0.739. FIG. 9 is a graph showing average values and standard deviations.

  It can be seen that the average value of the C synthesis amount is larger in Example than in Comparative Example 1. Both the standard deviation σ and the variation coefficient are smaller in the example. Significant differences were observed for the Mann-Whitney U test. Therefore, it can be seen that in the examples, carbon nanotubes with a larger amount of C synthesis than in Comparative Example 1 were stably produced.

(Configuration of manufacturing apparatus of Comparative Example 2 and manufacturing conditions and evaluation results)
Carbon nanotubes were produced using the carbon nanotube production apparatus 1 ″ by flame synthesis shown in FIG. The same components as those of the manufacturing apparatus 1 of the embodiment and the manufacturing apparatus 1 ′ of the comparative example 1 are denoted by the same reference numerals and description thereof is omitted.

  The structure of the catalyst raw material supply unit 35 and the cocatalyst supply unit 41 is different from that of the manufacturing apparatus 1 ′ of Comparative Example 1. In the catalyst raw material supply unit 35, ferrocene was vaporized by supplying argon gas to a ferrocene solution in which ferrocene was dissolved in 3-phenoxytoluene, which is an organic solvent, and bubbling the ferrocene, and the ferrocene was supplied into the reactor. In the co-catalyst supply section 41, argon gas was supplied to bubbling 2-hexylthiophene and bubbled to supply it into the reactor.

  In Example and Comparative Example 2, it was confirmed by SEM analysis and Raman spectroscopic analysis that single-walled carbon nanotubes were produced in all samples.

  First, carbon nanotubes were produced by setting the temperature of 2-hexylthiophene to 0 ° C. Table 6 shows the gas types and gas flow rates supplied to the first pipe 4, the second pipe 5, and the third pipe 6. Table 7 shows the temperature conditions during the production of the carbon nanotubes. In the table, “Furnace” is the temperature condition of the heating furnace 33, “Ferrocene” is the temperature condition of the ferrocene solution, “Hexylthiophene” is the temperature condition of 2-hexylthiophene, and “Burner” is the location where the catalyst and promoter are set. Shows the temperature condition of the pipe from immediately after (after) to the premixed flame 12. The carbon nanotube production time was 10 minutes.

Table 8 shows the film weight, the Fe / C value, and the I _D / I _G value of the produced carbon nanotube. When the values of Fe / C and I _D / I _G are compared with the average values of the examples, it can be seen that the values of the examples are better.

  Next, the experiment was conducted by setting the temperature of 2-hexylthiophene to 20 ° C. and supplying a promoter. Table 9 shows the gas types and gas flow rates supplied to the first pipe 4, the second pipe 5 and the third pipe 6, Table 10 shows the temperature conditions during the production of carbon nanotubes, and Table 11 shows the production of carbon nanotubes. The evaluation result of is shown. The displays in Tables 9 and 10 are the same as those in Tables 6 and 7. The carbon nanotube production time was 10 minutes. Under the conditions (a) and (b), the experiment is performed twice, and the results are expressed as (a-1), (a-2), (b-1), and (b-2).

The collected carbon nanotubes have Fe / C values of 13.8 and 1.11 for (a), 2.99 and 2.58 for (b), 5.75 for (c), and I _D / I _G for (a) 0.222 and 0.055, (b) is 0.051 and 0.016, and (c) is 0.147. Compared with the average values of the examples, it can be seen that the examples are better values with less variation.

Next, an experiment was conducted by changing the supply amount of ferrocene. Table 12 shows the gas types and gas flow rates supplied to the first tube 4, the second tube 5 and the third tube 6, Table 13 shows the temperature conditions during the production of the carbon nanotubes, and Table 14 shows the carbon nanotube production. An evaluation result is shown. The displays in Tables 12 and 13 are the same as those in Tables 6 and 7. The carbon nanotube production time was 10 minutes. Under the condition (a), the experiment was performed twice, and the results are expressed as (a-1) and (a-2). The values of Fe / C and I _D / I _G of the carbon nanotubes are 1.58 to 3.34 and 0.023 to 0.625, respectively. Compared with the average values of the examples, the examples have better variations and better It turns out that it is a value.

  Based on the above, a solution in which a large amount of a metal catalyst source is dissolved in a high-boiling solvent and a liquid promoter source are prepared, and the metal catalyst and the promoter are vaporized by bubbling and supplied to the reactor. Compared to Example 2, carbon nanotubes can be produced with higher crystallinity and better quality by using the catalyst precursor composition according to the present invention in which the metal catalyst source is a solute and the promoter is a solvent. I understand.

  Although the present invention has been described based on the embodiments and examples, the present invention can be variously modified. For example, as another example, 5 g of sulfur was added to 5 g of methyltrioctylammonium bis (trifluoromethanesulfonyl) imide as an ionic liquid and stirred at 120 ° C. for 1 hour to obtain a uniform solution. Further, when a glass plate was placed at the container outlet and nitrogen was bubbled, yellow sulfur crystals were deposited on the glass plate. Similarly, when 0.5 g of ferrocene was added to 5 g of methyltrioctylammonium bis (trifluoromethanesulfonyl) imide and stirred at 120 ° C. for 1 hour, a uniform solution was obtained. When a glass plate was placed at the outlet of the vessel and nitrogen was bubbled, yellow ferrocene crystals were deposited on the glass plate. In any case, volatilization of the ionic liquid could not be confirmed. From these facts, it is understood that sulfur and ferrocene can be mainly introduced into the reaction apparatus even if an ionic liquid is added to the sulfur and ferrocene solution.

2 Carbon nanotube
11 Catalyst precursor composition

Claims (8)

  A catalyst precursor composition for producing carbon nanotubes containing an organic transition metal complex compound as a solute and a sulfur-containing component as a solvent.   Contains a total of 0.1 to 10% by weight of transition metals with respect to the elemental sulfur, the boiling point of the sulfur-containing component is 50 ° C. or more and 1000 ° C. or less at 1 atm, and the sulfur-containing component contains 10% by mass or more as the sulfur element The catalyst precursor composition according to claim 1, wherein the catalyst precursor composition is liquid in a range of 0 ° C. to 200 ° C.   The organic transition metal complex compound is at least one selected from ferrocene, 1,1-dimethylferrocene, pentamethyl ferrocene, acetyl ferrocene, benzoyl ferrocene, cyclopentadienyl iron carbonyl dimer, cobalt cene, nickel ferrocene, and tetracarbonyl nickel. The catalyst precursor composition according to claim 1 or 2.   The sulfur-containing component is at least one selected from sulfur, thiophene, methylthiophene, ethylthiophene, hexylthiophene, benzothiophene, dibenzothiophene, tetrahydrothiophene, sulfolane, tetramethylene sulfoxide, an alkylthiol having 3 or more carbon atoms, and thiophenol. The catalyst precursor composition according to any one of claims 1 to 3.   It is a manufacturing method of the catalyst precursor composition of any one of Claims 1-4, Comprising: The manufacturing method of a catalyst precursor composition including the process of dissolving an organic transition metal complex compound in the fuse | melted sulfur-containing compound. Vaporizing the catalyst precursor composition according to any one of claims 1 to 4,
Supplying the vaporized organic transition metal complex compound and the vaporized sulfur-containing component into a reaction furnace;
Supplying a carbon source gas into the reaction furnace.   The method for producing carbon nanotubes according to claim 6, wherein the vaporizing step is a step of bubbling and vaporizing the catalyst precursor composition at any temperature within a range of 0 to 400 ° C. Means for vaporizing the catalyst precursor composition according to any one of claims 1 to 4,
Means for supplying the vaporized organic transition metal complex compound and the vaporized sulfur-containing component into a reaction furnace;
An apparatus for producing carbon nanotubes, comprising: means for supplying a carbon source gas into a reaction furnace.