KR20080000033A - Method of manufacturing catalyst for synthesis of carbon nanotubes and apparatus for manufacturing the same - Google Patents

Abstract

A preparation method of a catalyst for synthesis of carbon nanotubes is provided to mass-produce the catalyst for synthesis of carbon nanotubes effectively such that the catalyst is finely powdered to a particle size of about scores of nanometers, and a preparation apparatus of a catalyst for synthesis of carbon nanotubes is provided to realize the preparation method efficiently by the continuous process. A preparation apparatus of a catalyst for synthesis of carbon nanotubes includes: a solution generating unit(110) for mixing and agitating a catalytic precursor, a supported precursor and a solvent to generate a catalytic mixed solution; an atomization unit(120) for receiving the catalytic mixed solution from the solution generating unit to atomize the catalytic mixed solution; a pyrolysis reaction unit(130) for receiving an atomized catalytic mixed solution from the atomization unit and pyrolyzing the atomized catalytic mixed solution to generate a powdered support-catalyst complex; and a collection unit(140) for collecting the powdered support-catalyst complex. The atomization unit is a spraying apparatus. The spraying apparatus includes a spraying gas inlet(122) into which spraying gas flows to push the catalytic mixed solution into the pyrolysis reaction unit. The collection unit includes a blocking filter(144) for blocking the support-catalyst complex such that the powdered support-catalyst complex is not emitted into the outside.

Description

Method of manufacturing catalyst for synthesizing carbon nanotubes and apparatus for manufacturing same {Method of Manufacturing Catalyst for Synthesis of Carbon Nanotubes and Apparatus for Manufacturing the Same}

1 is a cross-sectional view conceptually illustrating an apparatus for preparing a catalyst for carbon nanotube synthesis according to an embodiment of the present invention.

<Short description of the symbols in the drawings>

51, 53: transfer pipe 110: solution generating unit

112: stirrer 120: atomization unit

122: atomizing gas inlet 132: heater

134: pyrolysis reactor 140: collection unit

142: collecting unit 144: blocking filter

146: gas outlet

The present invention relates to a method for producing a catalyst for synthesizing carbon nanotubes and a manufacturing apparatus thereof, and more specifically for synthesizing carbon nanotubes capable of effectively producing a large amount of finely powdered catalyst for synthesizing carbon nanotubes on the order of tens of nm. The present invention relates to a production method of a catalyst and a production apparatus capable of efficiently implementing the production method as a continuous process.

Carbon nanotubes are hollow tube-shaped carbon structures, which consist of two layers of single-walled carbon nanotubes (SWCNTs) and single-walled carbon nanotubes. Double walled carbon nanotubes (DWCNTs) in concentric form, thin multi-walled carbon nanotubes (t-MWCNTs) consisting of three to six single-walled walls, and thick walled walls It is classified as thin multi-walled carbon nanotube (MWCNT).

Due to their structural, electrical, optical, and electronic characteristics, these carbon nanotubes have various applications in field emission display devices, transistors, gas sensors, composites, secondary batteries, fuel cells, hydrogen storage, and nano devices. have. As a general synthesis method, arc discharge method, laser deposition method, plasma chemical vapor deposition method, thermochemical vapor deposition method, vapor phase synthesis method, pyrolysis method and the like are widely known. In the gas phase synthesis method, which is easy for mass synthesis, carbon nanotubes are prepared by using a hydrocarbon gas such as acetylene, ethylene, or methane as a carbon raw material, and using a transition metal such as nickel, cobalt, or iron as a catalyst in powder form. Metals act as catalysts to decompose hydrocarbon gas, a raw material, and also nucleate carbon nanotubes.

Powders of the catalyst may be sol-gelled transition metal solution, ion-exchange or ion-adsorption precipitation with a support, magnesium oxide (MgO), silica (SiO ₂ ), alumina (Al ₂ O). ₃ ) or the method of supporting on zeolite, mixing with precursor solution of support and burning it, are widely known.However, in this method, the sintering process is inevitably followed by the removal of solvent and It is difficult to mass-produce catalyst powder for carbon nanotube synthesis because there is a sifting process to obtain a constant powder

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preparing a catalyst for carbon nanotube synthesis that can effectively produce a large amount of a catalyst for synthesizing finely powdered carbon nanotubes on the order of several tens of nm.

Another object of the present invention is to provide a catalyst manufacturing apparatus for synthesizing carbon nanotubes, which can efficiently implement the preparation method by a continuous process.

In order to prepare a catalyst for synthesizing carbon nanotubes according to an aspect of the present invention, a catalyst mixture solution is prepared by dissolving a catalyst precursor and a supported precursor in a solvent. The catalyst mixed solution is atomized by a spray device or the like. The atomized catalyst mixture solution is pyrolyzed to form a powdered support-catalyst combination. The carrier-catalyst combination is collected to prepare a catalyst for synthesizing carbon nanotubes.

The pyrolysis of the atomized catalyst mixture solution is carried out at a temperature of 150 to 1200 ° C, preferably at a temperature of 600 to 700 ° C.

The catalyst mixed solution concentration is adjusted to 5 to 50% by weight, preferably 10 to 30% by weight. As a solvent for forming the catalyst mixture solution, water is preferably used.

A catalyst manufacturing apparatus for synthesizing carbon nanotubes according to an aspect of the present invention includes a solution generating unit for generating a catalyst mixed solution by mixing and stirring a catalyst precursor, a supported precursor, and a solvent, and receiving the catalyst mixed solution from the solution generating unit. An atomization unit for atomizing the catalyst mixture solution, a pyrolysis reaction unit provided with an atomized catalyst mixture solution from the atomization unit to pyrolyze the atomized catalyst solution to produce a powdered carrier-catalyst combination, and the powdering A collection unit for collecting the supported carrier-catalyst combination is used.

As the atomization unit, a nozzle spraying apparatus or the like can be used. The nozzle spray device atomizes the catalyst mixture solution and supplies the atomized catalyst mixture solution to the pyrolysis reaction unit.

Hereinafter, the present invention will be described in detail.

Manufacturing method of catalyst for carbon nanotube synthesis

The method for preparing a catalyst for synthesizing carbon nanotubes according to the present invention comprises the steps of i) dissolving a catalyst precursor and a supported precursor in a solvent to prepare a catalyst mixture solution, ii) atomizing the catalyst mixture solution. Iii) pyrolysing the atomized catalyst mixture solution to form a powdered support-catalyst combination, and iv) collecting the support-catalyst combination.

Upon completion of each step, the catalyst precursor is converted into a catalyst component and the supported precursor is converted into a support that supports the catalyst precursor. The support is combined with the catalyst so that the catalyst is uniformly dispersed without aggregation with each other.

The catalyst precursor contains a transition metal, and examples of the catalyst precursor include metal salts containing transition metals such as iron, nickel, cobalt, palladium, tungsten, chromium and iridium. The metal salt is present in hydrate form before dissolving. That is, the catalyst precursor initially has the form of a hydrate such as Fe (NO ₃ ) ₂ .9H ₂ O, Ni (NO ₃ ) ₂ .6H ₂ O, Co (NO ₃ ) ₂ .6H ₂ O, or the like.

The catalyst precursor may further include molybdenum-based compounds such as molybdenum acid and molybdenum metal salts. The molybdenum metal salts example, (NH _4), and the like ₆ Mo ₇ O ₂₄ 4H ₂ O and.

In addition, as a precursor for supporting the transition metal, magnesium metal salts such as magnesium nitrate, and the like, specifically Mg (NO ₃ ) ₃ .6H ₂ O or the like can be used. The supported precursor decomposes when the pyrolysis reaction is completed, and is converted into an oxide-type support, and combined with a catalyst to form a support-catalyst combination. Specifically, the oxide-transition metal conjugate is formed.

The catalyst precursor and the supported precursor are sufficiently dissolved in the solvent for 1 to 2 hours, thereby preparing a catalyst mixed solution. As the solvent, an organic solvent such as acetone, ethanol, benzene, thinner, or the like may be used, but the organic solvent may be decomposed during pyrolysis of the catalyst mixture solution as a hydrocarbon material to generate carbon-containing impurity compounds. Preference is given to using.

It is preferable to stir the solution sufficiently for uniform mixing during the dissolution process. In addition, the dissolution process is performed at room temperature.

The catalyst mixed solution preferably has a concentration of 5 to 50% by weight, preferably 10 to 30% by weight. When the concentration exceeds 50% by weight, the catalyst mixture solution may not be sufficiently atomized through the ultrasonic spraying process, whereas when the concentration is less than 5% by weight, the process efficiency of the subsequent process may be rapidly lowered.

When the catalyst mixture solution contains Fe, Ni and Mg or Co, Mo and Mg, it is preferable to adjust the content of each precursor to 5 to 45% by weight, 0.5 to 5% by weight, 94.5 to 50% by weight, respectively. Do. More preferably from 10 to 30% by weight, from 1 to 3% by weight and from 89 to 67% by weight.

When the catalyst mixture solution is prepared, the catalyst mixture solution is atomized by a nozzle spray device or the like.

In the pyrolysis process, the solvent of the catalyst mixture solution is evaporated and converted into a gas, and at the same time the catalyst mixture solution particles are sintered and powdered. That is, the catalyst precursor is converted into a catalyst, and the supported precursor is decomposed to form an oxide. In addition, in this process, the transition metal, which is a catalyst, combines with the oxide to form a transition metal-oxide bond in powder form. Reaction products generated during other reactions are released as gaseous components.

The pyrolysis temperature is 150 to 1200 ° C, preferably 600 to 700 ° C.

The powder-type transition metal-oxide binder is collected and separated from the gas component, thereby preparing a catalyst for synthesizing carbon nanotubes according to the present invention.

The oxide powder obtained by the production method of the present invention has a particle size of several micrometers to several tens of micrometers, and the metal catalyst powder has a size of several nm. The metal catalyst powder is sprayed uniformly as a form combined with the oxide powder.

Hereinafter, a method for preparing the carbon nanotube synthesis catalyst of the present invention will be described in more detail with reference to specific examples. However, the technical spirit of the present invention is not limited by the following examples.

Example 1

Fe (NO ₃ ) ₂ ㆍ 9H ₂ O, (NH ₄ ) ₆ Mo ₇ O ₂₄ ㆍ 4H ₂ O, Mg (NO ₃ ) ₃ ㆍ 6H ₂ O is the atomic ratio of Fe: Mo: Mg is 1: 0.7: 0.03 Dissolve with 5 L of water as much as possible, and then mix uniformly at room temperature using a stirrer. Subsequently, while injecting the mixed solution into a spray sprayer, the reactor was preheated at 700 ° C. and sprayed at a rate of 50 L / min using air as a spraying gas to obtain a brown fine powder. When carbon nanotubes were prepared using the catalyst powder, multi-walled carbon nanotubes having a purity of 80% and an outer diameter of 20 to 50 nm could be obtained.

Hereinafter, a catalyst manufacturing apparatus for synthesizing carbon nanotubes according to an embodiment of the present invention will be described.

Catalyst manufacturing apparatus for carbon nanotube synthesis

1 is a cross-sectional view conceptually illustrating an apparatus for preparing a catalyst for carbon nanotube synthesis according to an embodiment of the present invention.

Referring to FIG. 1, the apparatus for preparing carbon nanotubes according to the present embodiment includes a solution generating unit 110, an atomizing unit 120, a pyrolysis reaction unit 130, and a collecting unit 140.

In the solution generating unit 110, the catalyst precursor, the supported precursor, and the solvent are mixed and stirred to prepare a catalyst mixed solution. In this embodiment, the solution generating unit 110 includes a stirrer 112 to perform the solution generation more efficiently.

The atomization unit 120 receives the catalyst mixture solution prepared in the solution generation unit 110 to atomize the catalyst mixture solution. Thus, the catalyst mixed solution can be converted into fine particles. The atomization unit 120 includes a spray gas inlet 122. Through the spray gas inlet 122, a spray gas is introduced to allow the catalyst mixture solution to be easily discharged to the pyrolysis reaction unit 130. The atomized catalyst mixture solution may be moved to the pyrolysis reaction unit 130 by the spraying gas. Nitrogen gas or the like may be used as the spraying gas.

In the present embodiment, a nozzle spray device is used as the atomization unit 120. The nozzle spray device is to atomize the catalyst mixture solution by drastically lowering the pressure of the high pressure catalyst mixture solution passing through the narrow nozzle (as discharged to the pyrolysis reaction unit 130).

The catalyst mixture solution generated in the solution generating unit 110 is transferred to the nozzle spraying device 120 by the first transfer pipe 51.

The atomized catalyst mixture solution in the nozzle spray device 120 is provided to the pyrolysis reaction unit 130. The pyrolysis reaction unit 130 pyrolyzes the particulate catalyst mixture solution passed through the nozzle spray device 120 to generate a powdered precursor-catalyst combination through a sintering process. In addition, the solvent component of the catalyst mixture solution is vaporized in the pyrolysis reaction unit 130 during this process. The velocity of the flowing gas in the pyrolysis reaction unit 130 is preferably maintained at 20 to 100 L / min to 30 to 70 L / min. The reaction temperature inside the pyrolysis reaction unit 130 is preferably maintained at 150 to 1200 ℃, preferably 600 to 700 ℃. When the reaction temperature is less than 150 ° C, the transition metal precursor may not be completely decomposed, whereas when it exceeds 1200 ° C, the flow rate may be lowered to condensate the solvent in the collection unit 140.

The pyrolysis reaction unit 130 is preferably preheated to a specific temperature within the temperature range set forth above before the atomized catalyst mixture solution is supplied.

The pyrolysis reaction unit 130 includes a heater 132 and a pyrolysis reaction furnace 134, and is spatially connected to the nozzle of the nozzle spray device 120. The heater 132 generates heat to heat the inside of the pyrolysis reactor 134. In the pyrolysis reactor 134, the atomized catalyst mixture solution is pyrolyzed, resulting in a powdered carrier-catalyst combination.

The pyrolysis product, the support-catalyst combination, by-product gas produced as a result of the reaction is sent to the collection unit 140.

The pyrolysis reaction unit 130 and the collection unit 140 are spatially connected by a second transfer pipe 53.

The collection unit 140 is provided with a carrier-catalyst combination, a by-product gas and a spray gas generated in the pyrolysis reaction unit 130. The collection unit 140 collects the carrier-catalyst binder powder and discharges the by-product gas and the spray gas to the outside.

The collection unit 140 includes a collection unit 142, a cutoff filter 144, and a gas outlet 146.

The cut filter 144 serves to pass the by-product gas and the spray gas and block the carrier-catalyst binder powder. Therefore, the blocked carrier-catalyst binder powder is collected in the collecting part 142 formed at the bottom of the collecting unit 140. The gas outlet 146 serves as a passage for discharging gas components such as a by-product gas and a spray gas that are not blocked by the cutoff filter 144.

As described above, according to the method for preparing a catalyst for synthesizing carbon nanotubes according to the present invention, a metal catalyst for synthesizing carbon nanotubes having a particle size of several tens of nm or less can be produced in large quantities. In particular, by sufficiently mixing the catalyst precursor and the supported precursor initially to prepare a solution, a finer metal catalyst can be produced, and further, the efficiency of the process can be increased.

Meanwhile, according to the apparatus for preparing carbon nanotube synthesis catalyst according to the present invention, the catalyst for synthesizing fine carbon nanotubes can be manufactured in a continuous process and the device structure is simple to further improve the efficiency of mass production and simplify the process. You can.

As described above, the present invention has been described by way of a limited embodiment, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains may make various modifications and variations from this description. Do. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims (15)

Dissolving the catalyst precursor and the supported precursor in a solvent to prepare a catalyst mixed solution; Atomizing the catalyst mixture solution; Pyrolyzing the atomized catalyst mixture solution to form a powdered support-catalyst combination; And A method for producing a catalyst for synthesizing carbon nanotubes comprising collecting the carrier-catalyst combination. The method of claim 1, wherein the catalyst precursor is a metal salt containing at least one metal selected from the group consisting of iron, nickel, cobalt, palladium, tungsten, chromium and iridium. . The method of claim 2, wherein the metal salt is present in the form of a hydrate. The method of claim 2, wherein the transition metal precursor further comprises at least one cocatalyst precursor selected from the group consisting of molybdenum metal salts and molybdic acid. The method of claim 1, wherein the supported precursor is a hydrate of magnesium nitrate. The method of claim 5, wherein the support is a magnesium oxide (magnesium oxide) method of producing a catalyst for synthesizing carbon nanotubes. The method of claim 1, wherein atomization of the mixed solution is performed by a nozzle spray method. The method of claim 1, wherein the pyrolysis of the atomized catalyst mixture solution is performed at a temperature of 150 to 1200 ° C. The method of claim 1, wherein the concentration of the catalyst mixture solution is 10 to 30% by weight. The method of claim 1, wherein the solvent is water. The method of claim 1, wherein the catalyst precursor and the supported precursor are dissolved for 1 to 2 hours. A solution generating unit for mixing and stirring the catalyst precursor, the supported precursor, and the solvent to generate a catalyst mixed solution; An atomization unit for receiving the catalyst mixture solution from the solution generation unit to atomize the catalyst mixture solution; A pyrolysis reaction unit receiving a atomized catalyst mixture solution from the atomization unit to pyrolyze the atomized catalyst solution to produce a powdered support-catalyst combination; And A catalyst manufacturing apparatus for synthesizing carbon nanotubes comprising a collecting unit for collecting the powdered support-catalyst combination. 13. The apparatus for preparing a carbon nanotube catalyst according to claim 12, wherein the atomization unit is a nozzle spraying device. The apparatus of claim 13, wherein the nozzle spray device comprises a spray gas inlet through which spray gas for pushing the catalyst mixture solution into the pyrolysis reaction unit is introduced. The method of claim 12, wherein the collection unit is a carbon nanotube synthesis catalyst production, characterized in that it comprises a blocking filter for blocking the carrier-catalyst combination so that the powdered carrier-catalyst combination is not released to the outside Device.

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