KR101781252B1 - Process for preparing aggregates of carbon nanotubes - Google Patents

Abstract

There is provided a method for producing a carbon nanotube aggregate in which a fluidized bed reaction is possible and dispersion characteristics are improved.
The method comprises the steps of: heating a carrier precursor containing a metal hydroxide of a layered structure to form a carrier; Supporting a catalyst metal or a catalyst metal precursor on the support to form a supported catalyst; And contacting the supported catalyst with the carbon-containing compound under a heating region to form a carbon nanotube aggregate.

Description

Technical Field [0001] The present invention relates to a process for preparing carbon nanotubes,

The present invention relates to a method for producing aggregates of carbon nanotubes. More particularly, the present invention relates to a method for producing a carbon nanotube aggregate having a fluidized bed reaction and improved dispersion characteristics.

BACKGROUND ART Conventionally, a conductive resin composite material in which a conductive filler such as carbon black, carbon fiber, or metal powder is mixed with a matrix resin such as a thermosetting resin or a thermoplastic resin to impart conductivity is known.

In order to impart high conductivity to such a composite material, it is necessary to add a considerable amount of conductive filler. However, if a large amount of conductive filler is added, the mechanical properties of the composite material may be adversely affected and the inherent characteristics of the resin may be deteriorated. As a result, a filler material capable of exhibiting sufficiently high conductivity with a small amount of content has been required.

Carbon nanotubes are attracting attention as filler materials exhibiting such performance. A CVD method (chemical vapor deposition method) is known as a method of producing carbon nanotubes. The CVD method includes a method of producing a catalyst metal in a gas phase in a reaction system using an organic metal complex or the like as a catalyst, A method of using it by carrying it, and the like are used.

In the CVD method using an organometallic complex or the like as a catalyst, there are many defects of the graphite layer to be produced, and if the heat treatment is not performed at a high temperature after the reaction, conductivity is not exhibited when it is added as a conductive filler Making it difficult to manufacture. The latter method of using a catalyst carrier can be divided into a method of using a substrate as a carrier (substrate method) and a method of using a powdery carrier, and in the case of industrially using the above substrate method, Since the substrate surface area can not be obtained, the apparatus efficiency is low and the produced carbon nanotubes must be recovered from the substrate, which increases the number of processes and is not economical and has not been put to practical use.

On the other hand, the method of using the powdery carrier is advantageous in that it has a higher specific surface area as compared with the method using the substrate, and that the reaction apparatus used for various chemical syntheses can be used as well as the efficiency of the apparatus.

As such a reactor, a fluidized bed reactor can be exemplified.

Fluidized bed reactors are reactor devices that can be used to perform a variety of multiphase chemical reactions. In such a fluidized bed reactor, the fluid (gas or liquid) reacts with the particulate solid material, typically the solid material is a catalyst having a small sphere shape, and the fluid flows at a velocity sufficient to float the solid material, The material behaves like a fluid.

Methods for producing carbon nanotubes using the fluidized bed reactor are disclosed in Korean Patent Application Publication Nos. 10-2009-0073346 and 10-2009-0013503, for example. When such a fluidized bed reactor is used, a gas is uniformly distributed in the reactor, and a dispersing plate is used so that a catalyst-like powder can not pass from the upper part to the lower part. As the dispersion plate, a porous plate, a bubble cap, a sieve, or a nozzle is generally used.

In the fluidized bed reactor, the gas flows upward from the lower portion of the dispersion plate to float the particle layer on the dispersion plate into a fluid state. However, the upflow of the gas only makes it impossible to mix the powder with the gas, or shortens the residence time of the particles in the reactor. In this case, due to strong Van der Waals attraction of the carbon nanotubes themselves, the carbon nanotube particles agglomerate and settle on the top surface of the dispersion plate. As the catalyst continuously accumulates and grows on the settled agglomerates, the size of the carbon nanotubes There is a problem that the fluidity of the entire reactor is significantly lowered. Such aggregation of carbon nanotubes occurs mainly when the structure of the carbon nanotubes has a bundle type structure, making mass production of carbon nanotubes difficult.

Korean Patent Registration No. 10-1126119 discloses a process for producing a carbon fiber agglomerate in which a bundle type carbon nanotube has a cocoon cocoon shape in a horizontal reaction furnace by using a supported catalyst in which a catalyst metal precursor is supported on a heat treated aluminum hydroxide carrier, Discloses a resin composite material containing a fiber agglomerate.

On the other hand, when the carbon nanotubes have an entangled type structure, an efficient fluidized bed reaction is possible, but there is a problem that the dispersibility required for commercial application of carbon nanotubes is low.

In addition, U.S. Patent No. 7,799,246 discloses a supported catalyst capable of producing a tufted carbon nanotube in a fluidized bed reactor.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing carbon nanotube aggregates by controlling the structure of carbon nanotube aggregates through changes in the composition and crystal structure of catalyst precursors.

According to an aspect of the present invention,

Heat treating the carrier precursor containing the layered metal hydroxide to form a carrier;

Supporting a catalyst metal or a catalyst metal precursor on the support to form a supported catalyst; And

And contacting the supported catalyst with the carbon-containing compound under a heating region to form aggregates of carbon nanotubes.

According to the present invention, it is possible to produce a carbon nanotube agglomerate having excellent dispersion characteristics while allowing a fluidized bed reaction using a supported catalyst for synthesizing carbon nanotubes capable of appropriately controlling the structure of aggregated carbon nanotubes.

1 is a schematic diagram of a fluidized bed reactor according to one embodiment.
Figure 3 shows an XRD pattern of a carrier precursor in which hydrotalcite and boehmite are mixed according to one embodiment.
5 is an SEM photograph of the carbon nanotube aggregates obtained in Example 2. Fig.
6 is an SEM photograph of the carbon nanotube aggregates obtained in Example 3. Fig.
7 is a SEM photograph of the carbon nanotube aggregates obtained in Comparative Example 1. Fig.

Hereinafter, the present invention will be described in detail. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

According to an embodiment of the present invention, there is provided a method for preparing a carbon nanotube aggregate, comprising: heating a carrier precursor containing a metal hydroxide of a layered structure to form a carrier; Supporting a catalyst metal or a catalyst metal precursor on the support to form a supported catalyst; And contacting the supported catalyst with the carbon-containing compound under a heating region to form a carbon nanotube aggregate. In particular, the ratio of the bundle-type carbon nanotubes and the bundling-type carbon nanotubes can be controlled by controlling the composition ratio of the layered metal hydroxide and the non-layered metal hydroxide in the carrier precursor.

Carbon nanotubes (CNTs) having a one-dimensional structure are carbon nanotubes (CNTs) having adjacent hexagonal honeycomb structures bonded to each other to form a carbon plane, and the carbon plane is cylindrically shaped to have a tube shape. Such carbon nanotubes exhibit metallic properties or exhibit semiconducting properties depending on the structure, that is, depending on the directionality of hexagons in the tube. Such a carbon nanotube may be classified as a single walled carbon nanotube when the tube is a single tube, and may be classified into a multi-walled carbon nanotube when two or more tubes are rolled. .

In addition, the carbon nanotubes may be classified into a tufted or bundle-type structure depending on the shape generated during the synthesis process.

As used herein, the term "bundle type" refers to a bundle or rope shape in which a plurality of carbon nanotubes are arranged or intertwined in parallel, unless otherwise specified. The term " entangled type " used in the present invention means a form having no uniform shape such as the bundle or rope shape.

Since the bundle-type carbon nanotubes are advantageous in terms of dispersion rather than tufts, dispersion energy in the polymer composite material or solution dispersion may be much lower. Such high dispersion characteristics can be progressively progressed from a macro size to a micro size and ultimately to a nano size dispersion unit.

However, the bundle-type carbon nanotube grows outwardly in the carbon nanotube bundle, sinks in the reactor due to agglomeration between the carbon nanotube aggregates due to the strong Van der Waals attraction between the carbon nanotubes, and the settled carbon nanotube deposit As the carbon nanotube is continuously deposited and grown, the size of the carbon nanotube deposit gradually increases, and the fluidity of the entire reactor is greatly lowered, thereby making it difficult to mass-produce. If the fluidity of the carbon nanotube is greatly deteriorated, And a uniform quality of the carbon nanotubes can not be obtained due to the uneven temperature inside the reactor.

On the other hand, when the carbon nanotubes have a tufted structure, since the carbon nanotubes are grown while being entangled in the aggregated body, carbon nanotube deposits are not generated, thereby enabling an efficient fluidized bed reaction. There is a problem that the dispersibility required for application is low.

Therefore, it is necessary to produce carbon nanotubes having an excellent dispersion property while enabling an efficient fluidized bed reaction by appropriately controlling the generation ratio of the bundle type and the tuft type in the production process of carbon nanotubes. To this end, in the present invention, in the step of forming a support for supporting a catalyst by heat-treating a material containing a layered metal hydroxide and a non-layered metal hydroxide as a carrier precursor, a layered structure metal hydroxide and a non- The composition ratio of the carbon nanotubes, i.e., the bundle shape and the tuft shape, can be controlled.

The layered metal hydroxide used for the carrier precursor may be a layered double hydroxide and may be used without limitation, and they may have a porous structure. Specifically, the metal hydroxide of the layered structure is a hydroxide containing at least one of magnesium, calcium, aluminum and silicon, and examples thereof include brucite, portlandite, hydrotalcite, Hydrocalumite, quintinite, talc, and the like can be used. As the carrier precursor, the non-laminar structure metal hydroxide may be used without limitation as long as it is not a layered double hydroxide, preferably has a porous structure, more preferably is hydroxide containing at least one of magnesium, calcium, aluminum, For example, it is possible to use artinite, serpentine, chrysotile, hydromagnesite, hydrocalcite, bayerite, hydrargillite, One or more of gibbsite, boehmite, diaspore, doyleite, nordstrandite, and the like can be used.

The carrier precursors usable in the present invention include metal hydroxide of layered structure alone, and they may be used in combination of two or more layered metal hydroxides. The carrier precursor may further include a non-layered metal hydroxide in addition to the metal hydroxide of the layered structure, and these metal hydroxide may be used in combination of two or more non-layered metal hydroxides. The carrier obtained by heating these materials is obtained as a metal oxide and contains the layered structure in a predetermined ratio.

Such carrier precursor may have an average diameter of, for example, 1 to 200 탆, and a BET specific surface area of 1 to 400 m ² / g may be used.

Hydrotalcite, which is an example of the carrier precursor, has recently attracted attention as a kind of a porous carrier precursor. Such hydrotalcite is an anionic clay having a characteristic of a layered double hydroxide, and is represented by the following formula. _{[M (II) 1-x} M (III) x (OH) 2] x + [A x / n n-] x -mH 2 O, wherein M (II) is an alkaline earth metal of magnesium, calcium and the divalent metal cation Lanthanum, lanthanum, cerium, samarium, transition metals such as chromium, manganese, iron, cobalt, nickel, copper and zinc. M (III) is a trivalent metal cation, and aluminum, A is an intercalation anion, carbonate ion, x is a number of 0.2 to 0.4, and m is a number of a crystal number of 4. The hydrotalcite synthesized in the above- The trivalent metal has a layered structure and uniformly bonds at a relatively wide range of the atomic level, so that the dispersibility and uniformity of the active metallic components are very high.

According to one embodiment, when the carrier having increased porosity by heat treatment of the hydrotalcite in the layered metal hydroxide as the carrier precursor is used alone, the obtained carrier also contains the layered metal oxide. When a mixture of hydrotalcite, which is a layered metal hydroxide, and boehmite, which is a non-layered metal hydroxide, is used as the carrier precursor, it becomes possible to reduce the content of the layered metal oxide in the carrier. That is, since the boehmite is a non-layered metal hydroxide, it is possible to appropriately control the content of the layer-structured metal oxide in the carrier by appropriately controlling the content ratio of hydrotalcite to boehmite.

For example, when hydrotalcite alone is used as the carrier precursor, the carrier obtained by the heat treatment will contain only the layered metal oxide, and if the boehmite is added to the carrier precursor in a predetermined ratio, that is, the boehmite content is increased The content of the layered metal oxide in the carrier is decreased.

By controlling the content ratio of hydrotalcite to boehmite, the content of the layered metal oxide in the carrier is controlled, and as a result, the structure of the resultant carbon nanotube aggregates can be controlled as they are contained in a predetermined ratio.

That is, the composition of the carbon nanotubes, that is, the ratio of bundle-type and bundle-type carbon nanotubes is changed as the composition ratio of the layered metal oxide in the carrier and the non-layered metal oxide is changed, and the content of the layer- As a result, the formation rate of the bundle-type carbon nanotubes increases more than that of the bundle-type carbon nanotubes. As a result, the structure of the carbon nanotubes can be controlled within a range capable of performing an efficient fluidized bed reaction while maintaining excellent dispersion characteristics. .

According to one embodiment, when boehmite is added in a proportion of 0 to 500 parts by weight based on 100 parts by weight of the hydrotalcite, the content of the layered metal oxide in the carrier decreases as the boehmite content increases do. Alternatively, the content ratio of hydrotalcite to boehmite in the carrier may be in the range of 0 to 1000 parts by weight based on 100 parts by weight of hydrotalcite.

In another embodiment, in order to provide an efficient fluidized bed reaction while maintaining excellent dispersion characteristics, it is necessary to control the ratio of the formation of the bundle-type carbon nanotubes to that of the bundling-type carbon nanotubes. As the carrier precursor, for example, Or a mixture of hydrotalcite and boehmite may be used, wherein the boehmite is present in an amount of from about 1 to about 1000 parts by weight, or from about 10 to about 500 parts by weight, based on 100 parts by weight of the hydrotalcite By weight.

The carrier precursor as described above forms a carrier for supporting a catalyst by heat treatment, and it is also possible to change the production ratio of the bundle-type / bundle-type carbon nanotube structure by changing the heating treatment conditions.

The conditions for the heating treatment of the carrier precursor may vary depending on the particle size and the impurity concentration of the carrier precursor to be used, but is usually about 300 to 1000 ° C, more preferably 400 to 1000 ° C, desirable. In general, when a carrier precursor is heat-treated to form a carrier, a short-time heat treatment is often performed at a high temperature, but it is also possible to obtain a homogeneous carrier raw material by heating at a suitable temperature for a relatively long time. The preferred heat treatment time is generally from about 1 minute to about 10 hours, for example from 30 minutes to 10 hours.

By such a heat treatment, the carrier may have a BET specific surface area of 50 to 300 m ² / g and an average diameter of 10 to 200 μm.

After the carrier precursor is converted into a carrier by the heat treatment as described above, a catalyst metal or a catalyst metal precursor is supported on the carrier to form a supported catalyst.

The catalyst metal used in the present invention is not particularly limited as long as it is a substance promoting the growth of carbon fibers. Examples of the catalytic metal include at least one kind of metal selected from the group consisting of Groups 3 to 12 of the 18-element type periodic table recommended by IUPAC in 1990. Among them, at least one kind of metal selected from the group consisting of 3, 5, 6, 8, 9 and 10 is preferable, and iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr) At least one metal selected from the group consisting of Mo, W, V, Ti, Ru, Rh, Pd, Pt and rare- Particularly preferred. Examples of the catalyst metal precursor include inorganic salts such as nitrates, sulfates and carbonates of catalyst metals, organic salts such as nitrates and acylates, organic complexes such as acetylacetone complexes, organic metal compounds and the like And is not particularly limited as long as it is a compound containing a catalytic metal.

It is widely known to control the reaction activity by using two or more of these catalytic metals and catalytic metal precursor compounds. For example, an element selected from iron (Fe), cobalt (Co), and nickel (Ni), an element selected from titanium (Ti), vanadium (V), and chromium (Cr), molybdenum (Mo), and tungsten ) Can be exemplified.

The supported catalyst used in the production process of the present invention is not particularly limited in its production method, but it is preferable to produce the supported catalyst by impregnating the carrier with a liquid containing a catalytic metal element to obtain a catalyst.

Specific examples include a method of dissolving or dispersing the catalytic metal precursor compound in a solvent, impregnating the solution or dispersion with a granular carrier, followed by drying.

The liquid containing the catalytic metal element may be an organic compound containing a liquid catalytic metal element or a compound containing the catalytic metal element dissolved or dispersed in an organic solvent or water.

For the purpose of improving the dispersibility of the catalytic metal element, a dispersant or a surfactant such as a cationic surfactant and an anionic surfactant may be added to the liquid containing the catalytic metal element. The concentration of the catalytic metal element in the liquid containing the catalytic metal element may be appropriately selected depending on the solvent and the kind of the catalytic metal. The content of the liquid containing the catalytic metal element mixed with the carrier is preferably equivalent to the amount of liquid absorbed by the carrier to be used.

Drying after sufficiently mixing the liquid containing the catalyst metal element and the carrier can be usually carried out at 70 to 150 ° C. Vacuum drying may be used for drying.

After the supported catalyst is prepared as described above, the supported catalyst and the carbon-containing compound are brought into contact with each other under the heating region to form the tufted and bundled carbon nanotubes.

Preferred examples of the carbon-containing compound include carbon monoxide, ethane, propane, butane, ethylene, propylene, butadiene, methanol, ethanol, propanol, butanol, acetylene, benzene, toluene, xylene and mixtures thereof. , Propylene, and ethanol.

In the method for producing the carbon nanotubes, a carrier gas can be used in addition to these carbon-containing compounds. As the carrier gas, a hydrogen gas, a nitrogen gas, a carbon dioxide gas, a helium gas, an argon gas, a krypton gas, or a mixed gas thereof can be used. However, a gas containing oxygen molecules such as air (i.e., oxygen in the molecular state: O ₂ ) deteriorates the catalyst, which is not suitable.

In general, the catalytic metal precursor compound may be in an oxidized state, so that the catalytic metal precursor compound can be reduced to a catalytic metal by contacting it with a reducing gas prior to contact with the carbon containing compound.

In the method of the present invention, the supported catalyst and the carbon-containing compound are brought into contact with each other under a heating zone, and it is possible to control the production ratio of the bundle-type carbon nanotubes and the bundle-type carbon nanotubes through the contact temperature. At this time, the temperature to be contacted varies depending on the carbon-containing compound to be used and the like, but is generally 400 to 1100 ° C, preferably 500 to 800 ° C. If the temperature is too low or too high, the amount of produced carbon nanotubes may be significantly lowered.

The method of producing carbon nanotube agglomerates of the present invention as described above can be applied to a manufacturing process using a fluidized bed reactor because an efficient fluidized bed reaction can be achieved while maintaining high dispersion characteristics.

Fluidized bed reactors are reactor devices that can be used to perform a variety of multiphase chemical reactions. In such a fluidized bed reactor, the fluid (gas or liquid) reacts with the particulate solid material, typically the solid material is a catalyst having a small sphere shape, and the fluid flows at a velocity sufficient to float the solid material, The material behaves like a fluid.

Fig. 1 shows an example of a fluidized bed reactor in which the supported catalyst of the present invention as described above is contacted with a carbon-containing compound under a heating zone to produce carbon nanotubes.

Referring to FIG. 1, an apparatus for producing a carbon nanotube aggregate is a reactor for synthesizing carbon nanotube aggregates. The reactor includes a main body 1 having an inner space; And a plurality of dispersion plates (2) located inside the body and having different pore sizes. At the bottom of the reactor, there are provided a raw gas supply part (3) and a discharge part (4) of a mixed gas of unreacted gas and reaction byproducts on the upper part. The internal reactant (5) flows by the introduced reaction gas. In the reactor main body 1, the reaction temperature is controlled by a heating furnace 6, a catalyst inlet pipe 7 is disposed on the upper side of the reactor body 1, and a discharge pipe 8 is disposed on the side And the generated carbon nanotubes are transferred. A plurality of such discharge pipes 8 may be installed in the upper and lower sides of the reactor.

The reactor used in the present invention is a chemical vapor deposition reactor, for example, a fluidized bed reactor.

In the fluidized bed reactor, the catalyst is uniformly distributed inside and the contact between the catalyst and the reaction gas is excellent, the heat is easily diffused during the exothermic reaction, and the retention time of the catalyst and the carbon nanotube as a target product in the reactor can be secured. The production ratio of carbon nanotubes) of carbon nanotubes can be produced. In addition, since continuous reaction is possible, it is excellent in productivity relative to reactor volume and mass production of carbon nanotubes is easy.

The resin used for the resin composite material in the preferred embodiment of the present invention is not particularly limited, but a thermosetting resin, a photo-curable resin or a thermoplastic resin is preferable.

As the thermosetting resin, for example, a polyamide, a polyether, a polyimide, a polysulfone, an epoxy resin, an unsaturated polyester resin, a phenol resin and the like can be used. As the photo-curing resin, for example, a radical curing resin (Epoxy resin, oxetane resin, vinyl ether-based resin) and the like can be used, and the like can be used as the binder resin (for example, acrylic oligomer such as polyester acrylate, urethane acrylate and epoxy acrylate, unsaturated polyester, As the thermoplastic resin, for example, a nylon resin, a polyethylene resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyarylate resin, a cycloolefin resin and the like can be used.

The composite material according to one embodiment has no problem in the production process and the secondary processability as well as the mechanical strength is not lowered and a carbon nanotube-thermoplastic resin composite material having sufficient electrical properties can be obtained even though a small amount of carbon nanotubes are added .

The composite material according to one embodiment can be molded by any known method such as injection molding, blow molding, press molding, and spinning, and can be processed into various molded articles. As the molded article, it can be used as an injection molded article, an extrusion molded article, a blow molded article, a film, a sheet, a fiber and the like.

In particular, the composite material of the present invention can be processed into a molded article such as a charge shielding material, an electric / electronic product housing, and an electric / electronic part, taking advantage of its excellent conductivity and excellent mechanical properties.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

Example 2

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A mixture of hydrotalcite and boehmite, which is an average diameter of 50 탆, of 33 parts by weight of magnesium and 67 parts by weight of aluminum on the basis of 100 parts by weight of metal, was heated at 600 캜 to obtain a carrier. 20 g (0.17 mol) ammonium vanadate, 14 g (0.073 mol) citric acid and 400 g (1.37 mol) cobalt nitrate hexahydrate are successively dissolved in 1.5 L distilled water to prepare a clear solution of wine color. 500 g of the carrier obtained by the heat treatment was mixed and aged to sufficiently impregnate the catalyst metal in the carrier. Most of the water was removed at 60 ° C, 60 mbar and 30 rpm through a vacuum stirring evaporator, , 30 mbar, 20 rpm to obtain a powder. The obtained powder was calcined at 400 ° C for 3 hours to obtain a supported catalyst.

FIG. 3 shows the XRD pattern of a mixture of hydrotalcite and boehmite particles used as a carrier precursor, whereby the carrier precursor is a mixture of a layered structure and a non-layered metal hydroxide.

The supported catalyst was used to react in a fluidized bed reactor using the fluidized bed reactor shown in FIG. 1 to prepare a carbon nanotube aggregate. The reaction tube of the fluidized bed carbon nanotube synthesizer was a quartz reactor having an inner diameter of 58 mm and a length of 1200 mm, and 3 g of the carbon nanotube for bed and the 2 g supported catalyst were mixed and injected. Nitrogen was supplied at 1000 sccm while the temperature was raised to the reaction temperature. When the temperature reached 670 ° C, carbon nanotube agglomerates were prepared for 2 hours by feeding nitrogen, hydrogen, and ethylene gas at a ratio of 3: 1: 1. SEM photographs of the carbon nanotube agglomerates thus prepared are shown in Fig.

3 wt% of the carbon nanotubes were mixed together with 97 wt% of polycarbonate resin, and then a pellet-form primary compound workpiece was obtained by using an extruder having a 25-cm twin screw and a screw length / diameter ratio of 40. The primary compound workpiece was dried at 120 ° C for 4 hours and then injected from an extruder to prepare a specimen.

Example 3

A mixture of hydrotalcite and boehmite, which is an average diameter of 50 탆, based on 100 parts by weight of metal and 10 parts by weight of magnesium and 90 parts by weight of aluminum, was heat-treated at 600 캜 to obtain a carrier. 20 g (0.17 mol) ammonium vanadate, 14 g (0.073 mol) citric acid and 400 g (1.37 mol) cobalt nitrate hexahydrate are successively dissolved in 1.5 L distilled water to prepare a clear solution of wine color. 500 g of the support obtained by the heat treatment was mixed and aged to sufficiently impregnate the catalyst metal in the carrier. Most of the water was removed at 60 ^° C, 60 mbar and 30 rpm through a vacuum stirring evaporator, ^o C, 30 mbar, dried at 20 rpm to obtain a powder. The obtained powder was calcined at 400 ° C for 3 hours to obtain a supported catalyst.

Carbon nanotube agglomerates were prepared in a fluidized bed reactor through the same procedure as in Example 2. SEM photographs of the carbon nanotube agglomerates thus prepared are shown in Fig.

3% by weight of the carbon nanotubes were mixed with 97% by weight of a polycarbonate resin, and the specimens were prepared through the same extrusion and extrusion processes as in Example 2.

Comparative Example 1

A gamma alumina particle having a specific surface area of 150 m ² / g and an average diameter of 70 μm, which is a non-layered metal oxide, was used as a carrier. 19 g (0.047 mol) iron nitrate iron hydrate was dissolved in 500 mL of distilled water in order to prepare a clear yellow solution.

The solution was mixed with 100 g of gamma alumina carrier, aged to sufficiently impregnate the catalyst metal in the carrier, and then most of the water was removed at 60 ° C, 60 mbar, and 30 rpm through a vacuum stirring evaporator, mbar, dried at 20 rpm to obtain a powder. The obtained powder was calcined at 400 ° C for 3 hours to obtain a supported catalyst.

Carbon nanotube agglomerates were prepared in a fluidized bed reactor through the same procedure as in Example 2. SEM photographs of the prepared carbon nanotube agglomerates are shown in Figure 7. 3 wt% of the carbon nanotubes were mixed with 97 wt% of polycarbonate resin, and the specimens were produced through the same extrusion and extrusion processes as in Example 2 .

Comparative Example 2

Aluminum hydroxide particles having an average diameter of 50 占 퐉 were heat-treated at 600 占 폚 to obtain a carrier. 14.5 g (36 mmol) iron nitrate iron hydroxide and 40.4 g (139 mmol) cobalt nitrate hexahydrate were successively dissolved in 200 mL of distilled water to prepare a clear solution. This solution was mixed with 70 g of the carrier obtained by heat treatment, and the catalyst metal was aged to sufficiently impregnate the carrier, and most of the water was removed at 60 ° C, 60 mbar and 30 rpm through a vacuum stirring evaporator, 30 mbar, 20 rpm to obtain a powder. The obtained powder was calcined at 600 캜 for 3 hours to obtain a supported catalyst.

Carbon nanotube agglomerates were prepared in a fluidized bed reactor through the same procedure as in Example 2. Carbon nanotube deposits were generated inside the reactor.

Experimental Example

The yields of the carbon nanotubes obtained in Examples 2 and 3 and Comparative Examples 1 and 2, the electrical conductivity of the injection specimen, and the weight of the carbon nanotube deposit in the fluidized bed reactor were measured, and the results are shown in Table 1 below.

division Example 2 Example 3 Comparative Example 1 Comparative Example 2 Carbon nanotube yield 11 11 10 12 Electrical Conductivity (Ohm / sq.) Less than 10 ⁹ 10 ¹¹ or less 10 ¹¹ or more - Carbon nanotubes
Sediment weight (g) 0.2 or less 0.2 or less 0.2 or less over 10

The yield of the carbon nanotubes was calculated according to the following equation (1).

&Quot; (1) "

Carbon nanotube yield = (weight of produced carbon nanotube agglomerate - weight of catalyst) / catalyst weight

The electrical conductivity is the surface resistance measured according to the conductivity meter (PINION company, SRM-110) of the injection specimen obtained in Examples 2 and 3 and Comparative Examples 1 and 2.

The weight of the carbon nanotube deposit indicates the weight of the carbon nanotube deposit produced when 2 g of the supported catalyst is used in the fluidized bed reactor.

As can be seen from the results shown in Table 5, Examples 2 and 3 according to the present invention exhibited similar or higher yields of carbon nanotubes as compared with Comparative Examples 1 and 2, and further improved electrical conductivity And carbon nanotube deposits were significantly lower than those of the other samples.

Claims (23)

Heat treating a support precursor containing a layered metal hydroxide and a non-layered metal hydroxide to form a porous support;
Supporting a catalyst metal or a catalyst metal precursor on the support to form a supported catalyst; And
And contacting the supported catalyst with the carbon-containing compound under a heating region to form a carbon nanotube aggregate in which the bundle type and the tuft type are mixed. delete The method according to claim 1,
The ratio of the metal hydroxide of the layered structure in the carrier precursor and the metal hydroxide of the non-layered structure is controlled so as to control the ratio of generation of the bundle-type carbon nanotubes and the bundling-type carbon nanotubes generated in the step of forming the carbon nanotube aggregate A method for producing aggregates of carbon nanotubes. The method according to claim 1,
Wherein the metal hydroxide of the layered structure is a layered double hydroxide. The method according to claim 1,
Wherein the metal hydroxide of the layered structure has a porous structure. The method according to claim 1,
Wherein the metal hydroxide of the layered structure is a hydroxide containing at least one of magnesium, calcium, aluminum, and silicon. The method according to claim 1,
Wherein the metal hydroxide of the layered structure comprises at least one of brucite, polytetrafluoroantimonate, hydrotalcite, hydrocalumite, quintinite and talc. The method according to claim 1,
Wherein the metal hydroxide of the non-layered structure is a hydroxide containing at least one of magnesium, calcium, aluminum, and silicon. The method according to claim 1,
Wherein the metal hydroxide of the non-laminar structure has a porous structure. The method according to claim 1,
Wherein the metal hydroxide of the non-laminar structure is at least one selected from the group consisting of artinite, serpentine, chrysotile, hydro-magneite, hydrocalcite, beareite, hydrazylite, gibsite, boehmite, diaspore, doylide, Wherein the carbon nanotube aggregate comprises at least one of the carbon nanotube aggregates. The method according to claim 1,
When the metal hydroxide of the layered structure is hydrotalcite and the metal hydroxide of the non-layered structure is boehmite,
Wherein the content ratio of hydrotalcite and boehmite is controlled to control the content ratio of magnesium to aluminum in the carrier. 12. The method of claim 11,
Wherein the carrier precursor comprises 1 to 300 parts by weight of boehmite based on 100 parts by weight of hydrotalcite. The method according to claim 1,
Wherein the production ratio of the bundle-type carbon nanotube and the bundling-type carbon nanotube is controlled by changing the heating temperature of the carrier precursor. 14. The method of claim 13,
Wherein the heating temperature of the carrier precursor is 200 to 900 占 폚. 14. The method of claim 13,
Wherein the heating time of the carrier precursor is 1 minute to 10 hours. The method according to claim 1,
Wherein the catalyst metal is a combination of an element selected from iron, cobalt and nickel and an element selected from titanium, vanadium and chromium and an element selected from molybdenum (Mo) and tungsten (W). The method according to claim 1,
Wherein the supported catalyst is obtained by impregnating a carrier with a liquid containing a catalytic metal element. The method according to claim 1,
Wherein the step of contacting the supported catalyst with the carbon-containing compound under a heating region is a chemical vapor deposition process. 19. The method of claim 18,
Wherein the chemical vapor deposition process is performed in a fluidized bed reactor. A carbon nanotube aggregate obtained by the production method of any one of claims 1 and 3 to 19. Carbon nanotube aggregates according to claim 20; And a resin composite material comprising at least one of a thermosetting resin, a photocurable resin, and a thermoplastic resin. The method according to claim 1,
Wherein the average diameter of the carrier precursor is 50-200 占 퐉. The method according to claim 1,
Wherein the specific surface area of the porous carrier is 50-300 m < 2 > / g.

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