JP6357215B2 - Continuous production process and catalyst for carbon nanotube production for mass production of multi-wall carbon nanotubes - Google Patents

Description

The present invention relates to a continuous production process for mass production of carbon nanotubes and a catalyst for producing carbon nanotubes. More specifically, the present invention relates to a catalyst for mass production of multi-walled carbon nanotubes, a continuous production process of carbon nanotubes, and a catalyst for producing carbon nanotubes.

  Carbon nanotubes, first discovered by Dr. Sumio Iijima in 1991, are tube-shaped materials in which one carbon is bonded to another carbon atom and a hexagonal structure. There is a substance. Carbon nanotubes are known as a promising new material in the future because of their excellent mechanical properties, excellent electrical selectivity, excellent field emission properties, and the properties of highly efficient hydrogen storage media. Therefore, it is known that carbon nanotubes can be applied to a wide range of technical fields such as aerospace, biotechnology, environmental energy, material industry, pharmaceutical medicine, and electronic computers.

  In order to produce carbon nanotubes on a large scale, research on the production of an appropriate catalyst and the production process of carbon nanotubes for synthesizing carbon nanotubes on a large scale has been actively conducted.

  In order to produce these carbon nanotubes on a large scale, the catalyst manufacturing process and the carbon nanotube manufacturing process can be designed in separate single processes or in one continuous manufacturing process. In the case where the catalyst is produced in another single process, there may be a problem that the catalyst activity is lowered due to the storage stability of the catalyst composition for producing carbon nanotubes produced in the catalyst production process.

  In other words, in the case of a catalyst composition for producing carbon nanotubes, not only the physical shape change such as aggregation and collapse between various metal elements of the catalyst but also the activity of the catalyst at high temperature decreases with time. Thus, it would have been difficult to synthesize carbon nanotubes with high purity and high yield in a catalyst composition after a considerable period of production.

Therefore, it is more preferable that the production process of the catalyst for producing carbon nanotubes and the production process of carbon nanotubes are connected in a single continuous production process and the reaction proceeds.
As catalyst metals for producing carbon nanotubes, metals such as iron (Fe), cobalt (Co), and nickel (Ni) are known. In addition to the above metals, metals such as chromium (Cr), manganese (Mn), molybdenum (Mo), vanadium (V), tungsten (W), tin (Sn), palladium (Pd), copper (Cu), etc. It is known to have catalytic activity for producing carbon nanotubes. Recently, in order to further enhance the activity of the catalyst, a supported catalyst in which a catalyst is supported on an inert support has been developed.

  PCT International Publication No. WO2010 / 047439 A1 (Patent Document 1) describes a supported catalyst for carbon nanotube synthesis, a method for producing the same, and a carbon nanotube using the same, a plurality of metal catalysts selected from Fe, Co or Ni. Catalysts supported on alumina, magnesium oxide or silica supports are disclosed.

  Further, Patent Document 1 discloses molybdenum (Mo) as an activator for promoting the catalytic activity of Fe, Co or Ni catalytic metals. At this time, looking at the role of molybdenum in the catalyst composition, the catalyst powder spray-dried in the catalyst production process is calcined at a high temperature of 500 to 600 ° C. for about 0.5 hours, and the catalyst metal and support of Fe, Co or Ni It is added to a heat stabilizer for preventing aggregation and collapse between (Al, Mg, Si). Therefore, molybdenum has been a selective component that is selectively added to the carbon nanotube production catalyst composition as necessary.

On the other hand, the present inventors have already developed a large number of catalyst compositions as catalyst compositions for producing multi-walled carbon nanotubes, which are as follows.
In US Pat. No. 8,048,821 (patent document 2) “Catalyst composition for producing thin multi-walled carbon nanotubes and method for producing the same”, carbon composed of [Fe _a : Al _b ] _x : M _y : Mg _z A catalyst composition for producing nanotubes is disclosed. At this time, Fe, Al represents iron, aluminum, oxide or derivative thereof as a catalytically active substance, Mg represents magnesium, oxide or derivative thereof as an inert support, M represents Co, Ni, Cr, Mn, One or more transition metals selected from Mo, W, V, Sn or Cu, or oxides and derivatives thereof are shown.

In US Pat. No. 8,673,807 (patent document 3) “catalyst composition for producing multi-walled carbon nanotubes”, a catalyst composition for producing carbon nanotubes comprising a composition of [Co _a : Al _b ] _x : M _y : Mg _z We are disclosing things. At this time, Co, Al represents cobalt, aluminum, oxide or derivative thereof as a catalytically active substance, Mg represents magnesium, oxide or derivative thereof as an inert support, M represents Ni, Cr, Mn, Mo, One or more transition metals selected from W, Pb, Ti, Sn or Cu, or oxides and derivatives thereof are shown.

In US Pat. No. 9,186,656 (Patent Document 4) “Catalyst composition for producing multi-walled carbon nanotubes”, a catalyst composition for producing carbon nanotubes comprising a composition of [Fe _a : Mo _b ] _x : M _y : Al _z We are disclosing things. At this time, Fe and Mo represent iron, molybdenum, oxides or derivatives thereof as catalytic active substances, Al represents aluminum, oxides or derivatives thereof as inert supports, M represents Co, Ni, Ti, Mn , W, Sn, or a plurality of transition metals selected from Cu or oxides or derivatives thereof.

  Therefore, looking at the constituents of the catalyst composition for producing multi-walled carbon nanotubes already developed by the present inventors, US Pat. No. 8,048,821 (Patent Document 2) contains Fe and Al as essential constituents. In US Pat. No. 8,673,807 (Patent Document 3), Co and Al are included as essential constituents. In US Pat. No. 9,186,656 (Patent Document 4), Fe and Mo are used as essential constituents. It was included.

  From the catalyst compositions disclosed in Patent Documents 2 to 4, the most preferable components of the catalyst composition for producing multi-walled carbon nanotubes are the main catalyst (Fe, Co), the auxiliary catalyst (Mo) and the support ( A catalyst composition composed of Al) is expected.

WO2010 / 047439 U.S. Patent Registration No. 8,048,821 U.S. Patent Registration No. 8,673,807 U.S. Patent Registration No. 9,186,656

  The problem to be solved by the present invention is to produce carbon nanotube production catalysts of various compositions by spray pyrolysis method based on catalyst composition (Fe, Co, Mo, Al) in a large-scale process. It is used to develop a method of continuously synthesizing and producing multi-walled carbon nanotubes in a fluidized bed reactor. It also defines an optimal content ratio such as the molar fraction of the optimal catalyst composition (Fe, Co, Mo, Al) for the production of multi-walled carbon nanotubes.

  Therefore, the present inventors have produced carbon nanotube production catalysts of various compositions by spray pyrolysis based on the catalyst compositions (Fe, Co, Mo, Al) already predicted in a large-scale process. Using this, multi-walled carbon nanotubes are continuously synthesized and produced in a fluidized bed reactor, and the production yield, purity, apparent density, etc. of multi-walled carbon nanotubes are measured and Fe, Co, Mo, Al By confirming the optimum content ratio such as the molar fraction of the present invention, the present invention has been completed.

The configuration of the present invention is:
1) Catalytic metal precursor for carbon nanotube production (including Fe, Co and Mo as constituent metal elements, sometimes simply “Fe, Co, Mo”) and support precursor (including Al as constituent metal element) A catalyst powder for producing carbon nanotubes is obtained by spray pyrolysis after water is dissolved in water;
2) supplying and fluidizing the catalyst powder to the fluidized bed reactor, injecting and supplying the raw material gas, and performing thermal vapor deposition of carbon on the catalyst particles at 600 to 900 ° C; and
3) Collecting and sorting the thermally deposited carbon nanotubes to obtain multi-walled carbon nanotubes;
In the continuous production process of multi-walled carbon nanotubes consisting of
The catalyst for producing carbon nanotubes comprises a main catalyst (constituent metal elements are Fe and Co, sometimes simply Fe and Co), a cocatalyst (constituent metal element is Mo) and a support (constituent metal element is Al). It is a catalyst composition, and the synthesis yield of catalytic carbon nanotubes is 1,400 to 3,000%, and it is to provide a continuous production process of multi-walled carbon nanotubes.

The catalyst synthesis yield is expressed by the formula [catalyst synthesis yield (%) = carbon nanotube synthesis amount / catalyst input amount × 100].
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In addition, the step 1)
i) A catalyst metal precursor for carbon nanotube production (containing Fe, Co and Mo as constituent metal elements) and a support precursor for carbon nanotube production (containing Al as constituent metal elements) are dissolved in water, and a catalyst solution is prepared. Producing, supplying 2-5 atmospheres of air to the atomizing gas, allowing external air to flow in, and spraying the catalyst solution from the nozzle;
ii) high-temperature pyrolysis of the catalyst solution sprayed inside the reactor at 600 to 1,200 ° C .; and
iii) obtaining a catalyst powder for the synthesis of carbon nanotubes;
The catalyst powder obtained has an apparent density of 0.03 to 0.4 g / ml.

Further, the catalyst metal precursor and the support precursor are characterized by being in one or more forms selected from metal nitrate, sulfate, alkoxide, hydrochloride or carbonate.
The spray gas pressure is 2.5 to 4.0 atm, and the high temperature pyrolysis temperature is 600 to 1000 ° C.

On the other hand, the above stage 2)
i) preheating the reaction chamber;
ii) supplying catalyst powder from the lower part of the reaction chamber and fluidizing it in the reaction chamber;
iii) a step of injecting and supplying a source gas comprising a reaction gas and a carrier gas from the lower part of the reaction chamber;
iv) thermal vapor deposition of carbon on catalyst particles fluidized in an updraft by rotation of a rotor in a reaction chamber at 600-900 ° C;
v) exhausting the exhaust gas; and
vi) screening and collecting multi-walled carbon nanotubes;
It is characterized by comprising.

  The reactive gas is one or more carbon source gases selected from saturated or unsaturated hydrocarbons having 1 to 4 carbon atoms, carbon monoxide, or benzene, and the carrier gas is helium, nitrogen, argon, or the like. It is an inert gas.

On the other hand, the carbon nanotube production catalyst has a composition of a metal element represented by the following formula.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, s represent the mole fraction of Fe, Co, Mo, Al,
p + q + r + s = 10
0.3 ≦ p ≦ 3.0, 0.1 ≦ q ≦ 3.5, 0.05 ≦ r ≦ 1.0, 2.0 ≦ s ≦ 8.5.

Moreover, the said catalyst for carbon nanotube manufacture has the composition of the metal element displayed below, It is characterized by the above-mentioned.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, s represent the mole fraction of Fe, Co, Mo, Al,
p + q + r + s = 10
0.5 ≦ p ≦ 2.5, 0.2 ≦ q ≦ 3.0, 0.1 ≦ r ≦ 0.8, 2.5 ≦ s ≦ 7.5.

  Another object of the present invention is to provide a multi-walled carbon nanotube having a diameter of 5 to 15 nm, a bundle diameter of 0.5 to 4 μm and an apparent density of 0.02 to 0.1 g / cc manufactured by the above method. .

  A further object of the present invention is to provide a carbon nanotube resin composite material having increased electrical conductivity, thermal conductivity, antistatic, electromagnetic wave shielding, and tensile strength obtained by nanocompositing multi-walled carbon nanotubes and plastic polymer resin. That is.

  The effect of the present invention is that a catalyst for producing carbon nanotubes of various compositions is produced by a spray pyrolysis method on the basis of a catalyst composition (Fe, Co, Mo, Al) in a large-scale process. A method of continuously synthesizing and producing multi-walled carbon nanotubes in a fluidized bed reactor is provided, and a catalyst composition (Fe, Co, Mo, Al) for producing multi-walled carbon nanotubes with high yield, high purity, and high apparent density is provided. ).

FIG. 1 shows one embodiment of an apparatus for producing a catalyst composition for producing carbon nanotubes by a spray pyrolysis method of the present invention. FIG. 2 shows one embodiment of the carbon nanotube production apparatus according to the thermal vapor deposition method of the present invention. FIG. 3 shows one embodiment of the production process of the catalyst composition for producing carbon nanotubes by the spray pyrolysis method of the present invention. FIG. 4 shows one embodiment of the manufacturing process of carbon nanotubes by the thermal vapor deposition method of the present invention.

The present invention
1) After dissolving catalyst metal precursor for carbon nanotube production (containing Fe, Co and Mo as constituent metal elements) and support precursor (containing Al as constituent metal elements) in water, spray pyrolysis method Obtaining a catalyst powder for producing carbon nanotubes;
2) supplying and fluidizing the catalyst powder to the fluidized bed reactor, injecting and supplying the raw material gas, and performing thermal vapor deposition of carbon on the catalyst particles at 600 to 900 ° C; and
3) Collecting and sorting the thermally deposited carbon nanotubes to obtain multi-walled carbon nanotubes;
In the continuous production process of multi-walled carbon nanotubes, the carbon nanotube production catalyst comprises a main catalyst (the constituent metal elements are Fe and Co), a cocatalyst (the constituent metal elements are Mo) and a support (the constituent metal elements are The present invention relates to a continuous production process of multi-walled carbon nanotubes, characterized in that the synthesis yield of catalyst carbon nanotubes is 1,400 to 3,000%.

The catalyst for producing carbon nanotubes used in the present invention has a metal element composition represented by the following formula.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, s represent the mole fraction of Fe, Co, Mo, Al,
p + q + r + s = 10
0.3 ≦ p ≦ 3.0, 0.1 ≦ q ≦ 3.5, 0.05 ≦ r ≦ 1.0, 2.0 ≦ s ≦ 8.5.

  On the other hand, the present invention provides a multi-wall carbon nanotube having a fine diameter of 5 to 15 nm, a bundle diameter of 0.5 to 4 μm and an apparent density of 0.02 to 0.1 g / cc, and a multi-wall carbon nanotube and a plastic polymer produced by the above method. An object of the present invention is to provide a carbon nanotube resin composite material in which electrical conductivity, thermal conductivity, antistatic, electromagnetic wave shielding, and tensile strength are increased by nanocompositing a resin.

Hereinafter, the present invention will be described in more detail.
The carbon nanotube production catalyst composition used in the present invention is produced by a spray pyrolysis method comprising the following steps (steps i) to iii)).

  FIG. 3 shows one embodiment of the production process of the catalyst composition for producing carbon nanotubes by the spray pyrolysis method of the present invention.

[Stage i)]
In step i), a catalyst metal precursor for producing carbon nanotubes (Fe, Co, Mo) and a support precursor for producing carbon nanotubes (Al) are dissolved in water to produce a catalyst solution, and air at 2 to 5 atmospheres Is supplied as an atomizing gas and external air is introduced to spray the catalyst solution from the nozzle.

The catalyst metal precursor and the support precursor are preferably in the form of one or more selected from metal nitrates, sulfates, alkoxides, hydrochlorides or carbonates.
In the apparatus for producing a carbon nanotube production catalyst composition in FIG. 1, first, a catalyst metal precursor for carbon nanotube production (Fe, Co, Mo) and a carbon nanotube production support precursor (Al) are dissolved in water, A catalyst solution is manufactured, and air, which is a spray gas in the gas supply unit (150), is supplied to the catalyst solution in the catalyst supply unit (140) at 2 to 5 atm, and the reactor ( 110) Spray inside. At this time, external air is introduced and injected into the reactor through the outside air dispenser (170).
The pressure of the air that is the atomizing gas is preferably 2.5 to 4.0 atm.

[Stage ii)]
Stage ii) is a stage in which the catalyst solution sprayed into the reactor at 600 to 1,200 ° C. is pyrolyzed at high temperature. At this time, the high temperature pyrolysis temperature of the catalyst solution is preferably 600 to 1000 ° C.

[Stage iii)]
Step iii) is a step of obtaining a catalyst powder for the synthesis of carbon nanotubes. The apparent density of the finally obtained catalyst powder is 0.03 to 0.4 g / ml. When the apparent density of the catalyst powder is 0.03 g / ml or less, the catalyst synthesis yield of carbon nanotubes is low because the catalyst content is too low. Further, even when the apparent density of the catalyst powder is 0.4 g / ml or more, the catalyst powder may be aggregated without being properly dispersed, and the catalyst synthesis yield of carbon nanotubes is also lowered.

  Therefore, when the apparent density of the catalyst powder for carbon nanotube synthesis is in the range of 0.03 to 0.4 g / ml, the catalyst synthesis yield of carbon nanotubes can be in the range of 1,400 to 3,000%.

Next, in the fluidized bed reactor shown in FIG. 2, the multi-walled carbon nanotubes are deposited by thermal vapor deposition in the following steps (steps i) to vi)).
FIG. 4 shows one embodiment of the manufacturing process of carbon nanotubes by the thermal vapor deposition method of the present invention.

[Stage i)]
Step i) is a step of preheating the reaction chamber to 600 ° C. The reaction chamber (210) is made of quartz or graphite which is a high heat resistant material in a reaction space for synthesizing carbon nanotubes.

[Stage ii)]
Stage ii) is a stage in which catalyst powder is supplied from the lower part of the reaction chamber and fluidized in the reaction chamber. The catalyst powder is supplied from the catalyst supply unit (220) and dispersed in the reaction chamber through the dispersion holes.

[Stage iii)]
Step iii) is a step of injecting and supplying a raw material gas comprising a reaction gas and a carrier gas from the lower part of the reaction chamber. Reaction gas which is one or more carbon source gas selected from saturated or unsaturated hydrocarbons having 1 to 4 carbon atoms, carbon monoxide, benzene, etc. from the source gas supply unit (230) and helium, nitrogen or argon A carrier gas which is an inert gas is injected into the chamber.

[Stage iv)]
Stage iv) is a stage in which carbon is deposited by thermal vapor deposition on the catalyst particles fluidized in the rising airflow by the rotation of the rotor in a reaction chamber of 600 to 900 ° C. Carbon supplied from one or more selected carbon source gases such as saturated or unsaturated hydrocarbons having 1 to 4 carbon atoms, carbon monoxide, or benzene is deposited on the catalyst particles by thermal vapor deposition.

[Stage v)]
Step v) is the step of exhausting the exhaust gas. Carbon is deposited on the catalyst particles in the reaction chamber by thermal vapor deposition, and the remaining raw material gas or a part of the catalyst is discharged to the outside through an exhaust gas discharge unit (260) located at the top of the reaction chamber.

[Stage vi)]
Step vi) is a step of selectively collecting the multi-walled carbon nanotubes. Multi-walled carbon nanotubes produced according to the method of the present invention have a fine diameter of 5 to 15 nm, a bundle diameter of 0.5 to 4 μm, and an apparent density of 0.02 to 0.1 g / cc.

Hereinafter, the catalyst composition for producing multi-walled carbon nanotubes used in the present invention will be described in more detail.
As catalyst metals for producing carbon nanotubes, metals such as iron (Fe), cobalt (Co), and nickel (Ni) are known.

  In addition to the above metals, metals such as chromium (Cr), manganese (Mn), molybdenum (Mo), vanadium (V), tungsten (W), tin (Sn), palladium (Pd), copper (Cu), etc. It is known to have catalytic activity for producing carbon nanotubes.

In addition, a supported catalyst is disclosed in which a catalyst is supported on an inert support (Al, Mg, Si, etc.) in order to further enhance the activity of the catalyst.
In addition, we have already identified that Mo is the most useful cocatalyst that improves catalyst activity and compatibility with the Al support, US Pat. No. 9,186,656, our prior invention. It is disclosed in “Catalyst composition for producing multi-wall carbon nanotubes”.

  In addition, the present inventors have already registered in US patent registration, which is our prior invention, that Al is an inert support and is the most useful support for simultaneously promoting the catalytic activity of the main catalyst and Mo. No. 8,048,821 and US Pat. No. 8,673,807.

  Therefore, the present inventors have determined whether any of the catalytic metals of Fe, Co, and Ni, which are known as the main catalyst, shows the synergistic effect of the highest catalytic activity when mixed with the promoter Mo and the support Al. It has been studied. That is, it was tested by the production process of the spray pyrolysis catalyst of the present invention and the continuous synthesis process of carbon nanotubes in the fluidized bed reactor, and the catalyst composition with the highest synthesis yield of the multi-walled carbon nanotube catalyst was confirmed. .

The catalyst composition for producing carbon nanotubes developed by the present invention has a composition of a metal element represented by the following formula.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, s represent the mole fraction of Fe, Co, Mo, Al,
p + q + r + s = 10
0.3 ≦ p ≦ 3.0, 0.1 ≦ q ≦ 3.5, 0.05 ≦ r ≦ 1.0, 2.0 ≦ s ≦ 8.5.

Moreover, the said catalyst for carbon nanotube manufacture has a composition of the metal element shown below.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, s represent the mole fraction of Fe, Co, Mo, Al,
p + q + r + s = 10
0.5 ≦ p ≦ 2.5, 0.2 ≦ q ≦ 3.0, 0.1 ≦ r ≦ 0.8, 2.5 ≦ s ≦ 7.5.

The multi-walled carbon nanotubes produced by the present invention have excellent mechanical properties, electrical selectivity, excellent field emission properties, and high efficiency hydrogen storage medium properties.
Moreover, the carbon nanotube resin composite material in which the multi-walled carbon nanotube and the plastic polymer resin of the present invention are nanocomposited exhibits high electric conductivity, thermal conductivity, antistatic property, electromagnetic wave shielding, and tensile strength.

In addition, the multi-walled carbon nanotube produced based on the method of the present invention has a fine diameter of 5 to 15 nm, a bundle diameter of 0.5 to 4 μm, and an apparent density of 0.02 to 0.1 g / cc.
Further, it is judged that the multi-walled carbon nanotube of the present invention can be applied to a wide range of technical fields such as aerospace, biotechnology, environmental energy, material industry, pharmaceutical medicine, and electronic computer in the future.

[Example]
Hereinafter, the present invention will be described in detail with reference to production examples, production comparison examples, and examples.
(Production Example 1) Production of catalyst composition for carbon nanotube synthesis of the present invention
Catalyst 1 (Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5)
2.0 mol Fe (NO ₃ ) ₃ · 9H ₂ O, 2.0 mol Co (NO ₃ ) ₂ · 6H ₂ O, 0.5 mol (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O in 1 L of deionized water 5.5 mol of Al (NO ₃ ) ₃ · 9H ₂ O was added and stirred at room temperature for 2 hours to prepare a mixed catalyst solution in which all metal salts were completely dissolved. The prepared catalyst mixed solution was thermally decomposed by spraying 0.3 L / hour in the reactor of the spray pyrolysis apparatus using air as a transport gas. At this time, the spray pyrolysis conditions were as follows: the pressure of air was 3 atm, the temperature in the reactor was 750 ° C., and continuous operation was performed for 120 minutes to recover a total of 57 g of the catalyst composition. The molar ratio of the metals used for the production of the catalyst was Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5, and the apparent density of the produced catalyst composition was 0.28 g / mL.

(Production Example 2) Production of carbon nanotube synthesis catalyst composition of the present invention
Catalyst 2 (Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5)
2.0 mol Fe (NO ₃ ) ₃ · 9H ₂ O, 2.0 mol Co (NO ₃ ) ₂ · 6H ₂ O, 0.5 mol (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O in 1 L of deionized water 5.5 mol of Al (NO ₃ ) ₃ · 9H ₂ O was added and stirred at room temperature for 2 hours to prepare a mixed catalyst solution in which all metal salts were completely dissolved. The prepared catalyst mixed solution was thermally decomposed by spraying 0.3 L / hour in the reactor of the spray pyrolysis apparatus using air as a transport gas. At this time, the spray pyrolysis conditions were that the pressure of air was 3 atm and the temperature in the reactor was 850 ° C., and continuously operated for 120 minutes to recover a total of 53 g of the catalyst composition. The molar ratio of the metals used for the production of the catalyst was Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5, and the apparent density of the produced catalyst composition was 0.25 g / mL.

(Production Comparative Example 1) Production of catalyst composition for carbon nanotube synthesis (difference in molar ratio)
Catalyst C-1 (Fe / Co / Mo / Al = 0.1 / 3.9 / 0.5 / 5.5)
In 1 L of deionized water, 0.1 mol of Fe (NO ₃ ) ₃ · 9H ₂ O, 3.9 mol of Co (NO ₃ ) ₂ · 6H ₂ O, 0.5 mol of (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O 5.5 mol of Al (NO ₃ ) ₃ · 9H ₂ O was added and stirred at room temperature for 2 hours to prepare a mixed catalyst solution in which all metal salts were completely dissolved. The prepared catalyst mixed solution was thermally decomposed by spraying 0.3 L / hour in the reactor of the spray pyrolysis apparatus using air as a transport gas. At this time, the spray pyrolysis conditions were such that the air pressure was 3 atm and the temperature in the reactor was 750 ° C., and the operation was continuously performed for 120 minutes to recover a total of 52 g of the catalyst composition. The molar ratio of the metals used for the production of the catalyst was Fe / Co / Mo / Al = 0.1 / 3.9 / 0.5 / 5.5, and the apparent density of the produced catalyst composition was 0.38 g / mL.

(Production Comparative Example 2) Production of carbon nanotube synthesis catalyst composition (difference in thermal decomposition temperature)
Catalyst C-2 (Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5)
2.0 mol Fe (NO ₃ ) ₃ · 9H ₂ O, 2.0 mol Co (NO ₃ ) ₂ · 6H ₂ O, 0.5 mol (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O in 1 L of deionized water 5.5 mol of Al (NO ₃ ) ₃ · 9H ₂ O was added and stirred at room temperature for 2 hours to prepare a mixed catalyst solution in which all metal salts were completely dissolved. The prepared catalyst mixed solution was thermally decomposed by spraying 0.3 L / hour in the reactor of the spray pyrolysis apparatus using air as a transport gas. At this time, spray pyrolysis conditions were that the pressure of air was 3 atm and the temperature in the reactor was 400 ° C., and the operation was continuously performed for 120 minutes to recover a total of 66 g of the catalyst composition. The molar ratio of the metals used for the production of the catalyst was Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5, and the apparent density of the produced catalyst composition was 0.41 g / mL.

(Production Comparative Example 3) Production of catalyst composition for carbon nanotube synthesis (coprecipitation method)
Catalyst C-3 (Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5)
2.0 mol Fe (NO ₃ ) ₃ · 9H ₂ O, 2.0 mol Co (NO ₃ ) ₂ · 6H ₂ O, 0.5 mol (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O in 0.5 L of deionized water And 5.5 mol of Al (NO ₃ ) ₃ · 9H ₂ O were added and stirred at room temperature for 2 hours to prepare a solution A in which all metal salts were completely dissolved. 4 mol of NH ₄ .HCO ₃ was added to 1 L of deionized water and stirred for 2 hours to prepare a completely dissolved solution B. Both solutions A and B were combined at room temperature and stirred for 60 minutes. Thereafter, the obtained solid was filtered, washed with deionized water and recovered. The recovered filter cake was dried in air at 120 ° C. for 12 hours. The dried filter cake was pulverized and then calcined in air at 600 ° C. for 4 hours. The calcined powder was ground again to obtain 81 g of a catalyst composition. The molar ratio of the metals used for the production of the catalyst was Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5, and the apparent density of the produced catalyst composition was 0.78 g / mL.

(Production Comparative Example 4) Production of catalyst composition for carbon nanotube synthesis (spray drying method)
Catalyst C-4 (Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5)
2.0 mol Fe (NO ₃ ) ₃ · 9H ₂ O, 2.0 mol Co (NO ₃ ) ₂ · 6H ₂ O, 0.5 mol (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O in 0.5 L of deionized water And 5.5 mol of Al (NO ₃ ) ₃ · 9H ₂ O were added and stirred at room temperature for 2 hours to prepare a solution A in which all metal salts were completely dissolved. 4 mol of NH ₄ .HCO ₃ was added to 1 L of deionized water and stirred for 2 hours to prepare a completely dissolved solution B. Both solutions A and B were combined at room temperature and stirred for 60 minutes. Thereafter, the obtained solid was filtered, washed with deionized water and recovered. The recovered filter cake was put into 1 L of deionized water and stirred again to prepare a catalyst mixed solution, and the powder dried at 230 ° C. was recovered using a spray dryer. The dried powder was calcined in air at 600 ° C. for 4 hours to obtain 95 g of a catalyst composition. The molar ratio of the metals used in the production of the catalyst was Fe / Co / Mo / Al = 2.0 / 2.0 / 0.5 / 5.5, and the apparent density of the produced catalyst composition was 0.92 g / mL.

(Production Comparative Example 5) Production of catalyst composition for carbon nanotube synthesis (without Mo)
Catalyst C-5 (Fe / Co / Al = 2.0 / 2.0 / 6.0)
In 1 L of deionized water, 2.0 mol of Fe (NO ₃ ) ₃ · 9H ₂ O, 2.0 mol of Co (NO ₃ ) ₂ · 6H ₂ O and 6.0 mol of Al (NO ₃ ) ₃ · 9H ₂ O were charged. The mixture was stirred at room temperature for 2 hours to prepare a mixed catalyst solution in which all metal salts were completely dissolved. The prepared catalyst mixed solution was thermally decomposed by spraying 0.3 L / hour in the reactor of the spray pyrolysis apparatus using air as a transport gas. At this time, the spray pyrolysis conditions were as follows: the pressure of air was 3 atm, the temperature in the reactor was 750 ° C., and continuous operation was performed for 120 minutes to recover a total of 67 g of the catalyst composition. The molar ratio of the metals used for the production of the catalyst was Fe / Co / Al = 2.0 / 2.0 / 6.0, and the apparent density of the produced catalyst composition was 0.40 g / mL.

(Example 1) Synthesis of carbon nanotubes Catalysts produced in Production Examples 1 and 2 (Catalyst 1 and Catalyst 2) and catalysts produced in Production Comparative Examples 1 to 5 (Catalysts C-1, C-2 and C) -3, C-4, and C-5), the catalyst powder is dispersedly supplied in the fluidized bed carbon nanotube synthesis reactor shown in FIG. Multiwall carbon nanotubes were produced by thermal vapor deposition of carbon on catalyst particles at ˜900 ° C. The raw material gas used at this time was ethylene as a carbon source gas and nitrogen gas was mixed as a carrier gas at a volume ratio of 3: 1. Table 1 shows the catalyst synthesis yield (%) and the apparent density of the produced multi-walled carbon nanotubes.

The synthesis yield of the catalyst and the synthesis amount of the carbon nanotube were calculated based on the following formula.
Catalyst synthesis yield (%) = Carbon nanotube synthesis / Catalyst input x 100
Synthesis amount of carbon nanotube = total weight of reaction product (M _total ) _{-weight of} catalyst (M _cat )

The catalyst composition of the present invention _{[Fe p, Co q, Mo} r, Al s] using the catalyst synthesis the yield of multiwall carbon nanotubes manufactured by a continuous manufacturing process of the present invention in the case of catalyst 1 2,420 %, And in the case of catalyst 2, 2,740%. However, catalysts C-1 (difference in catalyst composition molar fraction) and catalyst C-5 (without Mo), which are different from the catalyst composition of the present invention, show catalyst synthesis yields of 1,650% and 680%, respectively. It was. Further, the catalyst C-2 produced at a low pyrolysis temperature during the production of the catalyst by the spray pyrolysis method of the present invention showed a low catalyst synthesis yield of 1,390%. On the other hand, in the case of catalyst C-3 produced by the coprecipitation method and catalyst C-4 produced by the spray drying method, the catalyst synthesis yields were 920% and 1,140% lower, respectively. The catalyst C-5 made by Mo showed the lowest catalyst synthesis yield of 680%.

Accordingly, the catalyst composition of the present invention _{[Fe p, Co q, Mo} r, Al s] using the catalyst synthesis the yield of multiwall carbon nanotubes manufactured by a continuous manufacturing process of the present invention 1,400～3,000 %.

100: Catalyst generator
110: Reactor
120: Heating part
130: Nozzle
140: Solution supply unit
150: Gas supply unit
160: Outside air gas supply pipe
170: Outside air dispenser
200: Fluidized bed carbon nanotube synthesizer
210: Reaction chamber
220: Catalyst supply section
222: Catalyst
224: Catalyst supply pipe
230: Source gas supply unit
232: Raw material gas
234: Source gas supply pipe
240: Rotor
242: Rotating body
250: Heating part
260: Exhaust gas exhaust

Claims (10)

1) After dissolving catalyst metal precursor for carbon nanotube production (containing Fe, Co and Mo as constituent metal elements) and support precursor (containing Al as constituent metal elements) in water, spray pyrolysis method Obtaining a catalyst powder for producing carbon nanotubes;
2) supplying and fluidizing the catalyst powder to the fluidized bed reactor, injecting and supplying the raw material gas, and performing thermal vapor deposition of carbon on the catalyst particles at 600 to 900 ° C .;
It made; 3) to recover selected heat deposited carbon nanotubes, the stage of obtaining a multi-walled carbon nanotubes
In the multi-wall carbon nanotube continuous production process in which the steps 1) to 3) are connected in a single continuous process, the carbon nanotube production catalyst is composed of a main catalyst (the constituent metal elements are Fe and Co), an assistant. A catalyst composition comprising a catalyst (the constituent metal element is Mo) and a support (the constituent metal element is Al);
The multi-wall carbon nanotube continuous manufacturing process, characterized in that the synthesis yield of catalyst carbon nanotubes is 1,400-3,000%.
Catalyst synthesis yield (%) = Carbon nanotube synthesis / catalyst input x 100 Said step 1)
i) A catalyst metal precursor for carbon nanotube production (containing Fe, Co and Mo as constituent metal elements) and a support precursor for carbon nanotube production (containing Al as constituent metal elements) are dissolved in water, and a catalyst solution is prepared. Producing and supplying 2-5 atmospheres of air as a spray gas, allowing external air to flow in and spraying the catalyst solution from the nozzle;
ii) high-temperature pyrolysis of the catalyst solution sprayed inside the reactor at 600 to 1,200 ° C .; and
iii) obtaining a catalyst powder for the synthesis of carbon nanotubes;
2. The process for continuously producing a multi-walled carbon nanotube according to claim 1, wherein the apparent density of the catalyst powder obtained by the step is 0.03 to 0.4 g / ml.   The multilayer wall according to claim 2, wherein the catalytic metal precursor and the support precursor are in one or more forms selected from metal nitrate, sulfate, alkoxide, hydrochloride or carbonate. Carbon nanotube continuous manufacturing process.   The multi-walled carbon nanotube continuous manufacturing process according to claim 2, wherein the spray gas pressure is 2.5 to 4.0 atm, and the high temperature pyrolysis temperature is 600 to 1000 ° C. Stage 2) above is
i) preheating the reaction chamber;
ii) supplying catalyst powder from the lower part of the reaction chamber and fluidizing it in the reaction chamber;
iii) a step of injecting and supplying a source gas comprising a reaction gas and a carrier gas from the lower part of the reaction chamber;
iv) thermal vapor deposition of carbon on the catalyst particles fluidized in the updraft by rotation of the rotor in a reaction chamber at 600-900 ° C;
v) exhausting the exhaust gas ;
2. The multi-walled carbon nanotube continuous production process according to claim 1, comprising:   The reaction gas is at least one carbon source gas selected from saturated or unsaturated hydrocarbons having 1 to 4 carbon atoms, carbon monoxide, or benzene, and the carrier gas is selected from helium, nitrogen, or argon. The multi-wall carbon nanotube continuous manufacturing process according to claim 5, wherein the multi-walled carbon nanotube is a kind or more of an inert gas. The multi-walled carbon nanotube continuous production process according to any one of claims 1 to 6, wherein the carbon nanotube production catalyst has a composition of a metal element represented by the following formula.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, and s represent the mole fraction of Fe, Co, Mo, and Al,
p + q + r + s = 10
0.3 ≦ p ≦ 3.0, 0.1 ≦ q ≦ 3.5, 0.05 ≦ r ≦ 1.0, 2.0 ≦ s ≦ 8.5. The multi-walled carbon nanotube continuous production process according to claim 7, wherein the catalyst for producing carbon nanotubes has a composition of a metal element represented by the following formula.
_{Fe p, Co q, Mo r} , Al s
In the above formula
p, q, r, and s represent the mole fraction of Fe, Co, Mo, and Al,
p + q + r + s = 10
0.5 ≦ p ≦ 2.5, 0.2 ≦ q ≦ 3.0, 0.1 ≦ r ≦ 0.8, 2.5 ≦ s ≦ 7.5. The multi-wall carbon nanotube continuous production according to any one of claims 1 to 8, wherein the produced multi-wall carbon nanotube has a fine diameter of 5 to 15 nm, a bundle diameter of 0.5 to 4 µm, and an apparent density of 0.02 to 0.1 g / cc. Process. The multi-walled carbon nanotube is manufactured by the process according to claim 9, and then the plastic polymer resin is nanocomposited. The electrical conductivity, thermal conductivity, antistatic property, electromagnetic wave shielding, and tensile strength are A method for producing an increased carbon nanotube resin composite.

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