KR100696361B1 - Method for manufacturing carbon nanotubes from solid carbon sources and carbon nanotubes manufactured thereby - Google Patents

Abstract

The present invention provides a method for rapidly synthesizing carbon nanotubes from solid carbon using electromagnetic radiation, and carbon nanotubes produced thereby.

In the method for producing carbon nanotubes using the carbon of the solid phase of the present invention as a carbon source, by dispersing the catalyst on the carbon in the solid phase at a nano size, and radiating electromagnetic waves for a predetermined time to synthesize the carbon nanotubes, energy use is greatly increased. It can be reduced and synthesized without the need for vacuum equipment.

Carbon nanotubes, nanocomposites, carbon sources, electromagnetic waves

Description

Method for manufacturing carbon nanotubes produced by carbon nanotubes using carbon as a solid carbon source and carbon nanotubes manufactured by the same

1 is a schematic view for explaining the configuration of the apparatus for producing carbon nanotubes used in the present invention,

2 is a block diagram illustrating a method of manufacturing carbon nanotubes according to an embodiment of the present invention;

Figure 3 is a scanning electron microscope (SEM) photograph of the drawing magnified 50,000 times the activated carbon fiber to be used as a solid carbon source in the present invention,

4a and 4b are magnified scanning electron micrographs of 3,000 and 50,000 times enlarged carbon nanotubes synthesized from activated carbon fibers according to the production method of the present invention,

5 is a magnification scanning electron micrograph of 50,000 times magnification of a graphite foil to be used as a solid carbon source in the present invention;

6 is a magnification scanning electron micrograph of 50,000 times the carbon nanotubes synthesized from the graphite foil according to the manufacturing method of the present invention.

     <Description of Symbols for Main Parts of Drawings>

10 carbon source feeder 11 gas feeder

12: auxiliary gas supply 20: agitator

30 reactor 40 electromagnetic wave generator

The present invention relates to a solid phase synthesis method of carbon nanotubes, and more particularly, to a method for producing carbon nanotubes using carbon as a carbon source and to carbon nanotubes produced thereby.

In general, carbon nanotubes have been reported as new materials having high electrical conductivity, excellent thermal conductivity of 5 times that of copper, and strength of 100 times higher than steel of the same thickness, electron emission source, secondary battery, hydrogen storage, fuel cell. It is expected to be widely applied to monoelectronic devices, nano sensors, and high-performance composites.

The physical properties of the composite containing carbon nanotubes vary depending on the degree of dispersion of the carbon nanotubes.

As a method commonly used to uniformly disperse the carbon nanotubes, there is a method of adding a dispersant or changing the characteristics of the surface of the carbon nanotubes.

However, in these conventional methods, once the synthesized carbon nanotubes are mixed with other materials to produce a composite, there is a disadvantage in that there is a limit in obtaining a uniform dispersion.

On the other hand, when carbon nanotubes are synthesized from solid carbon, a composite is directly produced from a green body, and thus, carbon nanotubes can be uniformly dispersed. to be.

On the other hand, in the case of the composite using the carbon fiber, carbon nanotubes synthesized directly from the surface of the carbon fiber is expected to significantly increase the bond strength with the matrix.

In order to obtain a similar structure, a method commonly used for synthesizing carbon nanotubes from a carbon source gas ("Controlled growth of carbon nanotubes on graphite foil by chemical vapor deposition", Chemical Physics Letters, volume 335, pp. 141-149 (2001)), but is distinguished from the carbon source by the present invention.

A method for synthesizing carbon nanotubes using electromagnetic radiation has been developed by the present inventors (Korean Patent Publication No. 2002-23522), but gas was also used as a carbon source.

Examples of synthesizing carbon nanotubes from a solid carbon source include methods of synthesizing carbon nanotubes from bulk polymers or Diamond Like Carbon (DLC) ("Synthesis of carbon nanotubes from bulk polymer", Applied Physics Letters, volume 69). , pp. 278-279 (1996)], [see "Carbon nanotubes and nanostructures grown from diamond-like carbon and polyethylene", Applied physics A, volume 73, pp. 765-768 (2001)]. .

However, this method was also distinguished from the present invention in that an electric furnace heating method was used, and a long reaction time of 3 to 8 hours was required.

As a result, the inventors of the present invention have continued their intensive studies, and thus spurred the research on carbon nanotubes using microwave radiation such as microwaves to reach the present invention.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing carbon nanotubes corresponding to a low energy use synthesis method for rapidly synthesizing carbon nanotubes by synthesizing carbon nanotubes from a solid carbon source.

In addition, another object of the present invention is to produce a radio frequency radiation, such as RF (RF), microwave, and to produce a carbon nanotube quickly and simply by heating a catalyst in contact with the solid carbon and There is provided a product such as carbon nanotubes produced thereby.

According to one aspect of the present invention for achieving the above object, in the method for producing carbon nanotubes using carbon in a solid phase as a carbon source, the catalyst is dispersed on the carbon in the solid phase to a nano-size, electromagnetic waves for a predetermined time It provides a method for producing carbon nanotubes, characterized in that to synthesize the carbon nanotubes by spinning.

According to the present invention, an activated carbon fiber or graphite foil is used as the solid carbon source.

According to the present invention, the nano-sized catalyst is a metal group including iron (Fe), cobalt (Co) or nickel (Ni); A compound group containing some components of the metal group, such as metal sulfides, metal carbides, metal oxides, and metal salts; It is characterized in that it is any one selected from the group of organic compounds containing metals, such as cobalt naphtenate.

In addition, according to the present invention, the electromagnetic wave is characterized in that the microwave or RF.

In addition, according to the present invention, a stirring step of maintaining a uniform dispersion state by stirring by putting the catalyst dispersed in the nano-size in a solution containing the solid carbon source; A drying step of drying for a predetermined time in an oven apparatus maintaining a predetermined temperature; A gas composition step of creating a gas environment containing no carbon source in the reactor; And a step of synthesizing an electromagnetic wave for a predetermined reaction time at a controlled power corresponding to the material including the carbon source and the catalyst in the solid phase.

In addition, according to the present invention, the gas environment does not include a carbon source of the gas composition step is characterized in that consisting of a gas selected from argon, hydrogen, nitrogen and a mixture of argon and hydrogen.

In addition, according to the present invention, the electromagnetic wave is characterized in that the microwave or RF having an output value in the range of 400W ~ 1200W as a heating medium.

According to another aspect of the present invention for achieving the above object, there is provided a carbon nanotube manufactured by the method for producing carbon nanotubes using the carbon as a carbon source in the solid phase as described above.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

In the drawings, Figure 1 is a schematic diagram for explaining the configuration of the carbon nanotube manufacturing apparatus used in the present invention, Figure 2 is a block diagram for explaining the carbon nanotube manufacturing method according to an embodiment of the present invention. 3 is a scanning electron microscope (SEM) photograph of a magnification of 50,000 times the activated carbon fiber to be used as a solid carbon source in the present invention, Figures 4a and 4b is synthesized from the activated carbon fiber according to the production method of the present invention Is a scanning electron micrograph of a drawing in which the carbon nanotubes were expanded 3,000 times and 50,000 times. In addition, Figure 5 is a magnification scanning electron micrograph of 50,000 times the graphite foil to be used as a solid carbon source in the present invention, Figure 6 is a 50,000 times magnification of carbon nanotubes synthesized from the graphite foil according to the manufacturing method of the present invention One drawing surrogate scanning electron micrograph.

In the present invention, it is preferred to disperse the metal used as a catalyst on a solid carbon source in nano size. Thereafter, carbon nanotubes are synthesized, wherein an electromagnetic heating device is used.

The apparatus for producing carbon nanotubes used in the present invention (electromagnetic heating device) generates electromagnetic waves corresponding to a heating medium by quantitatively controlling the output value and the reaction time of any one of microwave and RF (Radio Frequency) by a predetermined size. It is preferable that it is a normal apparatus which is made to heat by the generation | occurrence | production of such an electromagnetic wave.

For example, the apparatus for manufacturing carbon nanotubes as shown in FIG. 1 has an apparatus configuration for performing heating in a reactor by generating electromagnetic waves, ie microwaves, among electromagnetic waves.

That is, the carbon nanotube manufacturing apparatus (electromagnetic heating device) is a carbon source supply via the corresponding pipe connected to the carbon source supply 10, the gas supply 11 does not include a carbon source, the auxiliary gas supply 12, respectively, The stirrer 20 coupled to receive the gas and manufactured to inject the catalyst through the opening / closing door, and the check valve and the filter of the output side of the stirrer 20 through the check valve and the filter of the stirrer 20 The reactor 30 piped to receive the contents, and the micrometer of the output value (eg 600 watts or 1200 watts) of the predetermined size quantitatively for a predetermined reaction time (60 seconds, 90 seconds) coupled to the reactor 30 And an electromagnetic wave generator 40 and an oven device (not shown) for generating waves in the reactor 30.

On / off valves, check valves, flow controllers (MFC), filters are systematically provided inside the carbon source feeder 10, the carbon source, such as activated carbon fiber or graphite foil through the agitator 20, the reactor 30 Is coupled to enter (or inject) the inside of the

In the same way, the corresponding on / off valve, check valve, flow controller (MFC) and filter are coupled to the gas supply 11 to provide argon (Ar), hydrogen (H ₂ ), nitrogen (N ₂ ) or argon (Ar). A gas containing no carbon source such as a mixture of hydrogen and hydrogen (H ₂ ) is quantitatively introduced (or injected) through the stirrer 20 or directly into the reactor 30.

Of course, the auxiliary gas supplier 12 also has a similar internal configuration (on / off valve, check valve, MFC, filter) to the auxiliary gas such as ammonia (NH ₃ ), hydrogen sulfide (H ₂ S), etc. 20) or to be quantitatively supplied directly into the reactor 20.

Here, the electromagnetic wave generator 40 basically includes an auto tuner, a power meter, an isolator and a dummy load, a magnetron and a launcher, an output value and a time adjustment function. It is preferable to have an external signal box, a power supply, and to be able to quantitatively generate microwaves in the reactor 20.

If, in the present invention, the electromagnetic heating device is configured to heat the contents in the reactor 30 as it generates RF, the electromagnetic wave generator 40 is composed of conventional heating RF amplification means and overall circuit device. The configuration of such RF-related means and apparatus will be configured similarly to conventional RF generating and heating apparatus.

The above-described electromagnetic wave heating device is configured to radiate electromagnetic waves by adjusting an output power to be applied to the inside of the reactor 30 according to a material, and the carbon nanotubes in a solid state in a few seconds to several tens of seconds by the electromagnetic heating device. It is synthesized inside the reactor 30 as

At this time, a gas that is not mixed with a carbon source such as argon (Ar), hydrogen (H ₂ ), nitrogen (N ₂ ), or a mixture of argon (Ar) and hydrogen (H ₂ ) is at least a gas supply 11 and an agitator 20. ), As it flows into the reactor 30 through a check valve and a filter interposed on the output side pipe of the stirrer 20, it is used as a means for removing impurities during carbon nanotube synthesis.

In the description of the present invention and in the following claims, the term 'material' means a solid carbon source, a catalyst, a gas containing no carbon source, and auxiliary gases such as ammonia (NH ₃ ) and hydrogen sulfide (H ₂ S). As consisting of means the contents to be filled in the reactor (30).

Catalysts, such as solid or liquid phases according to the method of the present invention is a metal group containing iron (Fe), cobalt (Co) or nickel (Ni) dispersed in nano-size on the solid carbon source, metal sulfide, metal Compounds containing some components of the metal group, such as carbides, metal oxides, and metal salts, and organic compound groups having metals such as cobalt naphtenate can be used.

As shown in FIG. 2, according to the present invention, a method of preparing carbon nanotubes using carbon in a solid state such as activated carbon fibers or graphite foil as a carbon source basically includes a nano-sized catalyst in a solution containing the solid carbon source. Stirring step (S10) to maintain a uniform dispersion state by stirring, drying step (S20) for drying for a predetermined time in an oven apparatus maintaining a predetermined temperature, and a gas environment in which the carbon source is not mixed in the reactor It is preferable to include a gas composition step (S30), and a synthesis step (S40) for emitting an electromagnetic wave for a predetermined reaction time and the output power (power) corresponding to a material including a solid carbon source, a catalyst of the drying step. .

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

First embodiment

Carbon nanotube manufacturing method using the carbon of the solid phase of the present invention as a carbon source is a method for synthesizing carbon nanotubes from activated elastic fibers using a carbon nanotube manufacturing apparatus (electromagnetic heating device) as described above with reference to FIG. It is starting.

First, as described above, in the present invention, 10 [mu] M of iron [Fe (III)] and hydroxylamine (hydroxylamine) as catalysts in a solvent such as water so that the catalyst can be evenly dispersed in the stirring step (S10). It was prepared at a concentration of 400 μM, and the activated carbon fiber as a solid carbon source was added to this solution and stirred.

Thereafter, as in the drying step (S20), the material containing at least uniformly stirred activated carbon fibers and the catalyst is dried for a predetermined time (for example, about 1 hour) to maintain an appropriate drying state in an oven apparatus maintaining 150 ℃ do.

Then, the reaction time was reacted for 90 seconds at 400W in the reactor of the electromagnetic radiation device in which argon gas was sufficiently flowed.

SEM images showing the surface of activated carbon fibers synthesized with carbon nanotubes 3,000 times and 50,000 times are shown in FIGS. 4A and 4B.

When compared with the SEM photograph (FIG. 3) of the original activated carbon fiber magnified 50,000 times, it was confirmed that the carbon nanotubes were synthesized on the activated carbon fiber through the reaction.

Second embodiment

Carbon nanotubes were synthesized from the graphite foil corresponding to the solid carbon source in the same or the same manner as the first embodiment.

6 shows an SEM image in which the surface of the synthesized graphite foil is magnified 50,000 times by maintaining the reaction value for 60 seconds at an output value of 1200 W in the reactor of the electromagnetic wave radiator.

When comparing the original graphite foil with the SEM picture (FIG. 5) magnified 50,000 times, it was confirmed that carbon nanotubes were synthesized on the graphite foil through the reaction.

Comparative Example 1

Implemented according to the method described in the first embodiment or the second embodiment described above, it is not very short as in the technical idea of the present invention by replacing with a general heating device instead of electromagnetic radiation 900 for a relatively short time (for example 10 minutes) As a result of maintaining the temperature at ℃ or 1000 ℃, it can be seen that the carbon nanotubes were not synthesized.

Comparative Example 2

The method disclosed in the present invention is applied mutatis mutandis, except that carbon nanotubes were not synthesized as a result of radiating electromagnetic waves (microwave or RF) to 400W, 800W, and 1200W for 60 seconds without dispersing the catalyst in the active fiber carbon. Could know.

In the present invention configured as described above, carbon nanotubes can be synthesized from a solid carbon source in a relatively short reaction time (several seconds or tens of seconds) than the conventional method, and the energy use efficiency is innovatively excellent, and impurities are contained. There is an effect of providing a carbon nanotube manufacturing method using a carbon as a carbon source in a solid state capable of synthesizing high quality carbon nanotubes in a minimized state.

That is, the carbon nanotube manufacturing method using the carbon of the solid phase of the present invention as a carbon source is a low-energy synthetic rice method for quickly and simply synthesizing carbon nanotubes from solid carbon using electromagnetic radiation. Using only carbon, to produce carbon nanotubes in a very short time, the synthesized carbon nanotubes are synthesized more uniformly, robust and fast, there is an advantage that can be applied as a high quality nanocomposite or electron emission source.

Claims (8)

In the method for producing carbon nanotubes using carbon as a solid carbon source, A method for producing carbon nanotubes, characterized in that the carbon nanotubes are synthesized by dispersing a catalyst in nano size on the solid carbon and radiating electromagnetic waves. The method of claim 1, A method for producing carbon nanotubes, comprising using activated carbon fibers or graphite foil as the solid carbon source. The method of claim 1, The nano-sized catalyst is a metal group including iron (Fe), cobalt (Co) or nickel (Ni); A compound group containing some components of the metal group, such as metal sulfides, metal carbides, metal oxides, and metal salts; A method for producing carbon nanotubes, characterized in that any one selected from the group of organic compounds containing metals, such as cobalt naphtenate. The method of claim 1, The electromagnetic wave is a method of producing carbon nanotubes, characterized in that the microwave or RF. The method of claim 1, A stirring step of maintaining a uniform dispersion state by stirring the catalyst dispersed in nano size in a solution containing the carbon source in the solid state; A drying step of drying using an oven apparatus after the stirring step; A gas composition step of creating a gas environment containing no carbon source in the reactor; And a step of synthesizing the electromagnetic wave for a predetermined reaction time at a power controlled to correspond to the material including the carbon source and the catalyst in the solid phase. The method of claim 5, The gas environment does not include a carbon source of the gas forming step is a carbon nanotube manufacturing method, characterized in that consisting of a gas selected from argon, hydrogen, nitrogen and a mixture of argon and hydrogen. The method of claim 5, The electromagnetic wave is a method for producing carbon nanotubes, characterized in that the microwave or RF having an output value in the range of 400W ~ 1200W as a heating medium. delete

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