JP2005298303A - Method for producing fullerene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a fullerene where the recovering rate of the fullerene from a soot material containing the fullerene is enhanced and where the amount of an organic solvent to be used is reduced. <P>SOLUTION: The method for producing the fullerene comprises a first step to obtain a first slurry matter (E) by mixing the soot material (A) containing the fullerene with a first organic solvent (B), a second step to obtain a first extracted liquid (C) dissolving the fullerene and a first residue (F) by separating the first slurry matter (E), a third step to obtain a second slurry matter (J) by mixing the first residue (F) with a second organic solvent (G) and a fourth step to obtain a second extracted liquid (H) dissolving the fullerene and a second residue (K) by separating the second slurry matter (J). The second extracted liquid (H) is used for the whole or a part of the first organic solvent in second and following performances. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for producing fullerene from a soot-like substance containing fullerene, and more particularly to a method for improving the recovery rate of fullerene in a soot-like substance and reducing the amount of organic solvent used.

In recent years, as shown in Patent Document 1, fullerenes called C60 and C70, which are closed-shell carbon clusters, have been proposed as new carbon materials. Since these materials are expected to exhibit unique physical properties due to their special molecular structure, research on their properties and application development has been actively promoted, such as diamond coating, battery materials, paints, heat insulating materials, lubrication, etc. Application to fields such as materials, pharmaceuticals, and cosmetics is expected.

As a fullerene production method, for example, as shown in Patent Document 2, a method for producing a fullerene by burning a carbon compound has been proposed, and at present, an aromatic hydrocarbon such as benzene and an oxygen-containing gas are introduced into a reactor. A method for producing fullerene by incomplete combustion under reduced pressure has also been proposed.

Furthermore, a solvent extraction method is known in which a soot-like substance containing fullerene is mixed with an organic solvent, and the fullerene is dissolved in the organic solvent, and a method for obtaining fullerene from the organic solvent in which the fullerene is dissolved is also proposed. .

Japanese Patent No. 2802324 Japanese National Publication No. 6-507879

However, in the above-described method for producing fullerene by the solvent extraction method, when separating a precipitate that does not dissolve in an organic solvent, an organic solvent in which fullerene is dissolved adheres to the precipitate, and the adhered organic solvent There was a problem that the fullerene contained therein could not be recovered, and the recovery rate of fullerene decreased. Further, when fullerenes in a soot-like substance are recovered by performing solvent extraction a plurality of times on the soot-like substance, the fullerene recovery rate is improved, but there is a problem that the amount of the organic solvent is increased.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for producing fullerene by improving the recovery rate of fullerene from a rod-like substance containing fullerene and reducing the amount of an organic solvent to be used. .

The method for producing fullerene according to claim 1, which meets the purpose, extracts a fullerene in the soot-like substance by bringing the soot-like substance containing fullerene into contact with an organic solvent containing the fullerene.

The method for producing fullerene according to claim 2, which meets the object, a first step of obtaining a first slurry by mixing a soot-like substance containing fullerene and a first organic solvent;
A second step of separating the first slurry to obtain a first extract solution and a first residue in which fullerene is dissolved;
A third step of mixing the first residue and the second organic solvent to obtain a second slurry,
A fourth step of separating the second slurry and obtaining a second extract solution and a second residue in which fullerene is dissolved,
The second extract is used for all or part of the first organic solvent after the second time.

3. The method for producing fullerenes according to claim 1 and 2, wherein: (1) an electrode made of a carbonaceous material such as graphite is used as a raw material, and the raw material is evaporated by arc discharge between the electrodes. Method (arc discharge method), (2) a method in which a high current is passed through a carbonaceous material to evaporate the material (resistance heating method), and (3) a method in which the carbonaceous material is evaporated by pulsed laser irradiation with a high energy density (laser) Evaporation method), (4) Incomplete combustion of organic substances such as benzene (combustion method), and the like are known.

The rod-like substance containing fullerene produced by the above-described method contains polycyclic aromatic hydrocarbons and insoluble carbonized substances in addition to fullerenes. In addition, the soot-like substance containing fullerene includes a case where it is a fullerene concentrate obtained by partially removing graphite, carbon black, and the like from the soot-like substance. A fullerene concentrate is obtained by concentrating fullerenes from a rod-like substance by various methods, and the concentration method is not particularly limited, but as an example, a fullerene sublimate obtained from a rod-like substance by a sublimation method, a solvent extraction method In addition to the fullerene-containing residue obtained by evaporating and drying the fullerene solution obtained in 1., fullerene-containing solids obtained by column chromatography separation of the soot-like substance, and mixtures thereof.
The soot-like substance containing fullerene may be a powdery or massive solid or may be dissolved in a liquid such as an organic solvent.

Examples of the organic solvent include organic solvents in which fullerene is soluble, such as aromatic hydrocarbons, aliphatic hydrocarbons, chlorinated hydrocarbons, and the like, which may be either cyclic or acyclic. These organic solvents may be used alone or in combination of two or more.

Here, the aromatic hydrocarbon is a hydrocarbon compound having at least one benzene nucleus in the molecule. For example, benzene, toluene, xylene, ethylbenzene, n-propylbenzene, isopropylbenzene, n-butylbenzene, sec -Butylbenzene, tert-butylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, 1,2,3,4-tetramethylbenzene, 1, Examples include alkylbenzenes such as 2,3,5-tetramethylbenzene, diethylbenzene, and cymene, alkylnaphthalenes such as 1-methylnaphthalene and 2-methylnaphthalene, and tetralin.

The aliphatic hydrocarbon can be either cyclic or acyclic. Cycloaliphatic hydrocarbons include monocyclic aliphatic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, cyclooctane, and derivatives thereof such as methylcyclopentane, ethylcyclopentane, methylcyclohexane, ethylcyclohexane, 1 , 2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, isopropylcyclohexane, n-propylcyclohexane, tert-butylcyclohexane, n-butylcyclohexane, isobutylcyclohexane, 1,2,4-trimethylcyclohexane, There is 1,3,5-trimethylcyclohexane, and examples of polycyclic aliphatic hydrocarbons include decalin. Examples of the acyclic aliphatic hydrocarbon include n-pentane, n-hexane, n-heptane, n-octane, isooctane, n-nonane, n-decane, n-dodecane, and n-tetradecane.

Further, chlorinated hydrocarbons include dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, 1-chloronaphthalene and the like. .
As the organic solvent, ketones having 6 or more carbon atoms, esters having 6 or more carbon atoms, ethers having 6 or more carbon atoms, carbon disulfide, or the like may be used.

Here, from an industrial viewpoint, among these organic solvents, those having a normal temperature liquid and a boiling point of 50 to 300 ° C., particularly 80 to 250 ° C. are suitable as the organic solvent for dissolving fullerene. Specifically, for example, benzene, toluene, xylene, methicylene, 1-methylnaphthalene, alkylbenzene such as 1,2,3,5-tetramethylbenzene, 1,2,4-trimethylbenzene, and / or naphthalene such as tetralin. Aromatic hydrocarbons such as derivatives are preferably used, and can be used alone or as a mixed solvent of two or more.

The fullerene production method according to claim 1, wherein the organic solvent containing fullerene is capable of dissolving fullerene, and is more than 0 and less than 0.8, preferably more than 0 and less than 0.5, with respect to the solubility of C60. It is preferable that more than 0 and less than 0.1 fullerene is dissolved.

In the fullerene production method according to claim 2, a stirring and mixing tank can be suitably used as an apparatus for extracting the fullerene by mixing the first and second organic solvents in the first step and the third step, respectively. At the time of extraction, the pressure in the container is not particularly limited, and may be carried out at normal pressure. The temperature at the time of extraction is, for example, 1 to 300 ° C., preferably 10 to 70 ° C., particularly preferably 10 to 50 ° C. from the viewpoint of improving the extraction efficiency. Therefore, it is advantageous in terms of energy cost to carry out at room temperature. Further, the extraction time may be 1 minute or longer, preferably 10 minutes or longer. However, since the extraction time has little influence on the extraction efficiency, there is no need for a long time. Just choose. Further, if necessary, it is preferable to perform extraction while irradiating the extraction liquid with ultrasonic waves or the like because the extraction time is shortened. Moreover, it is preferable to carry out in an inert gas.

Impurities having a molecular weight lower than that of C60 in the rod-like substance, C60, C70, and higher-order fullerene having a carbon number exceeding 70 are dissolved in the first organic solvent and extracted. The soot residue (for example, polycyclic aromatic hydrocarbon or insoluble carbonized product) is a substance insoluble in the first organic solvent (hereinafter referred to as insoluble substance). The insoluble substance and the first organic solvent (first extract) in which fullerene is dissolved constitute a first slurry.

The first residue obtained by separating the first slurry-like substance contains 20 to 25% by weight of an insoluble substance, and the remainder is a first organic solvent in which fullerene is dissolved, that is, a first extract. Is part of. Since fullerene is dissolved in the first extract, when the second organic solvent in which fullerene is soluble is further mixed with the first residue, the fullerene in the first residue is converted into the second organic solvent. It can be extracted and recovered as a second extract. In addition, the second residue, which is the remainder after separating the second extract from the second slurry substance, contains an insoluble substance to which a part of the second extract is attached. Here, since the fullerene is dissolved in the second extract attached to the second residue, the fullerene may be recovered by further mixing the second residue with an organic solvent.

Moreover, as an apparatus which isolate | separates a 1st or 2nd slurry-like thing, a filter and a centrifuge are used, for example, The solid-liquid separation method used normally can be selected suitably.
In the second extraction liquid used as the first organic solvent in the first step after the second time, fullerene can be dissolved, and the solubility of C60 is more than 0 and less than 0.8, preferably 0. More than 0.5 and more preferably more than 0 and less than 0.1 fullerene is dissolved.

The method for producing fullerene according to claim 3 is the method for producing fullerene according to claim 2, wherein the soot-like substance is obtained by combustion or thermal decomposition of a carbon-containing compound.
Here, as the carbon-containing compound used as a raw material for fullerene, aromatic hydrocarbons having 6 to 15 carbon atoms such as benzene, toluene, xylene, naphthalene, methylnaphthalene, anthracene, and phenanthrene are preferably used. Furthermore, you may use together aliphatic hydrocarbons, such as hexane, heptane, and octane, with these aromatic hydrocarbons.

Combustion is a method (combustion method) in which a carbon-containing compound is incompletely burned to obtain a soot-like substance containing fullerene. Thermal decomposition is a method (thermal decomposition method) in which a carbon-containing compound is decomposed at a high temperature to obtain a soot-like substance containing fullerene. By these methods, a soot-like substance containing a high concentration of fullerene can be produced, and the combustion method is particularly preferable.

As a device for producing this soot-like substance, for example, a device in which a (water-cooled) burner is installed in a decompression chamber and the system can be stably combusted while exhausting the system with a vacuum pump is used. The And as said burner, the thing of the structure which can implement | achieve the premixed laminar flame and diffusion flame of carbon containing compounds, such as benzene, and oxidizing gas is used.

As the flame conditions, it is necessary to conveniently select the C / O ratio (equivalent ratio), the combustion chamber pressure, the diluent concentration, the gas velocity, and the like. Specifically, the C / O ratio is, for example, 0.5 or more, preferably 1.08 to 1.56, the combustion chamber pressure is, for example, 1.60 to 13.36 kPa, and the diluent concentration is, for example, The gas velocity for discharging the burner to 0 or more than 0 and 40 mol% is set, for example, within a range of 75 cm / s to 1000 cm / s. In addition, although a general inert gas can be used as a diluent, it is preferable to use argon.

The soot-like substance produced by the combustion method has a carbon content by elemental analysis of usually 90% by weight or more, preferably 95% by weight or more, more preferably 98% by weight or more. It has a carbon material containing a small amount of a functional group such as a carboxyl group.
This carbon material is promising for use in applications where a high resistance carbon material such as a color filter-on-array, which is a new technology for liquid crystal displays, is required.

Further, since this carbon material is expected to be excellent in chargeability, it is also useful for applications utilizing the chargeability of carbon black, such as copying toner and e-paper in which carbon black is dispersed in a resin. It is considered to be a material. Further, this carbon material can be expected to be used as a filler in a coating composition, which is used for a member that requires thermal insulation, taking advantage of its low thermal conductivity.

The method for producing fullerene according to claim 4 is the method for producing fullerene according to claims 2 and 3, wherein the first and second organic solvents have a C60 solubility of 1 g / L or more, preferably 2 g / L or more. More preferably, it is 5 g / L or more.
Here, as the organic solvent, if the solubility of fullerene is too low, the extraction efficiency is lowered. As the organic solvent, 1,2,4-trimethylbenzene (1,2,4-trimethylbenzene; hereinafter simply referred to as TMB), o-xylene, and toluene are preferable.

The method for producing fullerene according to claim 5 is the method for producing fullerene according to claims 2 to 4, wherein the first organic solvent is mixed in an amount of 4 to 200 times by weight with respect to the weight of the soot-like substance.
Here, if the amount of the first organic solvent is less than 4 times the amount of the soot-like substance, the fluidity becomes poor, and it becomes difficult to separate the first slurry, exceeding 200 times the amount. In addition, the amount of the first organic solvent used is too large, resulting in poor economic efficiency and difficulty in removing it.

Further, the first organic solvent needs to be used in an amount that can sufficiently extract fullerene. The soot-like substance usually contains 5 to 30% by weight of fullerene. It is preferable to use 10 to 700 times by weight of this fullerene and 40 to 400 times by weight in consideration of economy. . Therefore, it is preferable to measure the fullerene content of the soot-like substance in advance.

The method for producing fullerene according to claim 6 is the method for producing fullerene according to claims 2 to 5, wherein one or both of the first and second slurry-like materials are separated by a vacuum filter, It is carried out by one or more of a filter and a centrifuge.
Here, the first and second slurry-like materials are aggregates (cakes) of fine particles in the first and second organic solvents, respectively. When the cake becomes thick (large), separation operation becomes difficult in separation where external force such as filtration at normal pressure is not applied. Therefore, a second step of separating the first slurry-like substance into the first extract and the first residue by physically applying force by filtration under reduced pressure and increased pressure, or by centrifugation, and The operation in the fourth step of separating the second slurry substance into the second extract and the second residue is facilitated.

The method for producing fullerene according to claim 7 is the method for producing fullerene according to claims 2 to 6, wherein the first extract is concentrated, and the solubility of the first and second organic solvents is A concentrated liquid having a fullerene concentration of 0.2 to 6 times by weight, preferably 0.5 to 2 times by weight.
Here, if the first extract is a concentrate less than 0.2 weight times the solubility of the first and second organic solvents, the fullerene concentration in the concentrate is small and post-treatment is difficult. In addition, if the concentrated solution exceeds 6 times by weight, fullerene that cannot be dissolved in the organic solvent may be precipitated as a solid and adhere to the inner wall of the concentration device. Therefore, it is preferable that the concentrator is capable of stirring and mixing. Moreover, it is preferable to operate in inert gas.

The method for producing fullerene according to claim 8 is the method for producing fullerene according to claim 7, wherein the concentrated liquid and a poor solvent in which fullerene is insoluble or hardly soluble are mixed to precipitate fullerene insoluble in the poor solvent. .

Here, examples of the poor solvent in which fullerene is insoluble or hardly soluble include alcohols, ketones, ethers and the like. Among these, alcohols having 1 to 4 carbon atoms, ketones having 3 to 5 carbon atoms, or ethers having 3 to 5 carbon atoms are preferable, and alcohols having 1 to 4 carbon atoms are more preferable. Among these alcohols, those having a boiling point lower than those of the first and second organic solvents are preferably used, and alcohols having 3 or less carbon atoms are preferably used. Specifically, methanol, ethanol, n-propanol, isopropanol, ethylene glycol, glycerin and the like are preferable. Among them, isopropanol and methanol are preferable, and methanol is particularly preferable. These poor solvents can be used alone or as a mixture of two or more.

By adding a poor solvent under a specific control, the solubility of the organic solvent in fullerenes is reduced, and C60, C70 and higher fullerenes having low solubility are precipitated, and impurities having a molecular weight lower than C60 are present in the solution. Remains. The poor solvent is added for 1 minute or longer, preferably 1 hour or longer, more preferably 3 hours or longer.

The method for producing fullerene according to claim 9 is the method for producing fullerene according to claim 8, wherein the poor solvent is a polar solvent having a solubility of C60 of 0.1 g / L or less, preferably 10 mg / L or less. When a poor solvent having a solubility of C60 of 0.1 g / L or less is used, fullerene is likely to precipitate.

The method for producing fullerene according to claim 10 is the method for producing fullerene according to claims 8 and 9, wherein the poor solvent is 0.1 to 20 times by weight, preferably 1 to 20% by weight with respect to the concentrated liquid. Mix the double amount.
Here, the poor solvent is less likely to cause precipitation of fullerene when mixed in an amount of less than 0.1 times by weight with respect to the concentrate, and the amount of poor solvent used when mixed in an amount exceeding 20 times by weight. It becomes too much and the economy is inferior, and the removal becomes difficult. In addition, although the addition method of a poor solvent is arbitrary, adding gradually is preferable.

A fullerene production method according to an eleventh aspect is the fullerene production method according to the eighth to tenth aspects, wherein the fullerene in the poor solvent is recovered using one or both of a pressure filter and a vacuum filter.
Here, the precipitated fullerene is an aggregate of fine particles (cake) in a poor solvent. When this cake becomes thick (large), a separation method that does not apply force from the outside, such as filtration at normal pressure, etc. The separation operation becomes difficult. Therefore, it can isolate | separate by giving a force physically by filtration by pressure reduction and pressurization.

In the method for producing fullerene according to claim 1, the fullerene-containing soot-like substance is brought into contact with the organic solvent containing fullerene and the fullerene in the soot-like substance is extracted, so that the organic solvent containing fullerene is reused. Can do.

In the method for producing fullerene according to claims 2 to 11, since the second extract is used for all or part of the first organic solvent after the second time, the supply amount of the first organic solvent can be reduced. Moreover, since the fullerene in the 1st residue obtained at the 2nd process is also collect | recovered, the recovery rate of fullerene from a soot-like substance becomes high. Furthermore, since fullerene is further dissolved in the second extract, fullerene recovery efficiency is improved.

In particular, in the method for producing fullerene according to claim 3, since the soot-like substance is obtained by combustion or thermal decomposition of a carbon-containing compound, a soot-like substance containing a large amount of fullerene can be produced. The amount of fullerene recovered increases. Moreover, the soot-like substance produced by combustion or pyrolysis is less mixed with carbon black or the like having a graphite structure, and the number of steps for removing it can be reduced. Moreover, a useful carbon material can be manufactured.

In the method for producing fullerene according to claim 4, since the solubility of C60 in the first and second organic solvents is 1 g / L or more, fullerene is easily dissolved in the first and second organic solvents. The recovery rate can be improved.

In the method for producing fullerene according to claim 5, since the first organic solvent is mixed in an amount of 4 to 200 times by weight with respect to the weight of the soot-like substance, the first organic solvent mixed with the soot-like substance is It has fluidity and can facilitate the separation operation.

The method for producing fullerene according to claim 6, wherein the separation of either one or both of the first and second slurry-like materials is one or more of a vacuum filter, a pressure filter, and a centrifuge. Therefore, the separation between the first extract and the first residue and the separation between the second extract and the second residue can be facilitated.

The method for producing fullerene according to claim 7, wherein the first extract is concentrated, and a concentrate having a fullerene concentration of 0.2 to 6 times the amount of the solubility of the first and second organic solvents, Therefore, a concentrated liquid containing fullerene at a high concentration can be obtained.

In the method for producing fullerene according to claim 8, the concentrated liquid and the poor solvent in which fullerene is insoluble or hardly soluble are mixed, and fullerene insoluble in the poor solvent is precipitated, so that fullerene and impurities can be separated, and high purity. Fullerenes can be manufactured.
In the method for producing fullerene according to claim 9, since the poor solvent is a polar solvent having a solubility of C60 of 0.1 g / L or less, fullerene can be precipitated.

In the method for producing fullerene according to claim 10, since the poor solvent is mixed in an amount of 0.1 to 20 times by weight with respect to the concentrated liquid, fullerene can be selectively precipitated, impurities are removed, and fullerene is obtained. Can do.
In the method for producing fullerene according to claim 11, since fullerene in the poor solvent is recovered using one or both of the pressure filter and the vacuum filter, the separation of fullerene from the poor solvent can be facilitated. it can.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory view of a fullerene production apparatus to which a fullerene production method according to an embodiment of the present invention is applied.

With reference to FIG. 1, a fullerene production apparatus 10 to which a fullerene production method according to an embodiment of the present invention is applied will be described in the order of steps. The operation of the fullerene production apparatus 10 is performed in an inert gas (for example, nitrogen gas).

(First step)
The fullerene production apparatus 10 applied to the fullerene production method according to an embodiment of the present invention is an apparatus that recovers fullerene from a soot-like substance (A) containing fullerene. Here, the soot-like substance (A) is produced by a combustion method in which toluene, which is an example of a carbon-containing compound, is incompletely burned with pure oxygen in the combustion furnace 12, and is stored in the soot-like substance tank 11. In addition, the soot-like substance to be used may be produced not only by the combustion method but also by any of arc discharge method, resistance heating method, and laser evaporation method, but the fullerene content in the soot-like substance (for example, The combustion method is suitably used from 10 to 30 wt% fullerene in the soot-like material produced by the combustion method. Reference numerals A to Q in parentheses correspond to the reference numerals of the substances described in the figure.

The fullerene production apparatus 10 dissolves fullerene in the soot-like substance (A), and 1,2,4-trimethylbenzene (1), which is an example of a first organic solvent having a C60 solubility of 1 g / L or more. , 2,4-trimethylbenzene, hereinafter referred to as TMB (B)). Here, TMB has a C60 solubility of about 18 g / L. In addition, the fullerene production apparatus 10 includes a first extraction tank 14 that mixes the soot-like substance (A) and TMB (B).

The first extraction tank 14 is provided with a stirring blade, efficiently mixes the soot-like substance (A) and TMB (B), dissolves the fullerene in the soot-like substance (A) in TMB (B), It is extracted. During this extraction, the pressure in the first extraction tank 14 is not particularly limited, and may be performed at normal pressure. The temperature at the time of extraction in the first extraction tank 14 is, for example, 1 to 300 ° C., preferably 10 to 70 ° C., particularly preferably 10 to 50 ° C. from the viewpoint of improving extraction efficiency. Since the temperature dependency is small, it is advantageous in terms of energy cost to perform at about room temperature. The extraction time may be 1 minute or longer, preferably 10 minutes or longer. However, since the extraction time has little influence on the extraction efficiency, there is no need for a long time. Just choose. Further, if necessary, it is preferable to perform extraction while irradiating the extraction liquid with ultrasonic waves or the like because the extraction time is shortened.

In the 1st extraction tank 14, the soot-like substance (A) and TMB (B) were mixed, and the 1st slurry-like thing (E) was obtained. The first slurry-like product (E) is composed of TMB (B) in which fullerene is dissolved, that is, the first extract (C) and the first insoluble substance (D) insoluble in TMB (B). . Since TMB (B) has a solubility of C60 of 1 g / L or more, fullerene in the soot-like substance (A) can be sufficiently extracted. TMB (B) is mixed in an amount of 4 to 200 times by weight with respect to the weight of the rod-like substance (A).

(Second step)
The fullerene production apparatus 10 includes a first continuous pressure filter 15 which is an example of an apparatus for separating the first slurry (E). The first slurry (E) is filtered with the first continuous pressure filter 15 to obtain the first extract (C). The first residue (F) separated at this time is a first insoluble substance (D) to which a part (C ′) of the first extract is attached.

Here, in the conventional fullerene production method, fullerene was recovered only from the first extract (C) separated from the first slurry (E). However, the first residue (F) separated from the first slurry (E) is 4 to 5 times the weight of the first extract (C) with respect to the weight of the first insoluble substance (D). ')have. In the present embodiment, the fullerene in the first extract (C ′) adhering to the first insoluble substance (D) is recovered, and the fullerene in the soot-like substance (A) is obtained in a high yield. The purpose is to get.

(Third step)
The fullerene production apparatus 10 includes a second extraction tank that mixes the first residue (F) separated from the first continuous pressure filter 15 and TMB (G), which is an example of a second organic solvent. 16. TMB (G) is supplied from the same organic solvent tank 13 as TMB (B) which is the first organic solvent. In the second extraction tank 16, the first residue (F) and TMB (G) are mixed, and the second extract (H) in which the fullerene in the first residue (F) is dissolved A second slurry (J) composed of the second insoluble substance (I) insoluble in TMB is obtained.

(4th process)
Furthermore, the fullerene production apparatus 10 includes a second continuous pressure filter 17 which is an example of an apparatus for separating the second slurry-like material (J). The second slurry (J) is filtered by the second continuous pressure filter 17 to obtain the second extract (H). The second residue (K) separated at this time is the second insoluble substance (I) to which a part (H ′) of the second extract is attached.

Here, in the fullerene production apparatus 10, the second extraction liquid (H) separated by the second continuous pressurization filter 17 is supplied to the first extraction tank 14, and further from the rod-shaped substance tank 11. The rod-like substance (A) is supplied to When the amount of the second extraction liquid (H) to be supplied is small with respect to the soot-like substance (A), TMB (B) is supplied from the organic solvent tank 13 to the first extraction tank 14. In this way, the second extract obtained in the previous fourth step is used for all or part of the first organic solvent in the first step after the second time, and the first to fourth steps are used. It can be repeated twice or more.

Next, a method for recovering fullerene from the first extract (C) obtained in the second step will be described.
The fullerene production apparatus 10 concentrates the first extract (C) obtained in the second step, and is 0.2 to 6 times the amount of the TMB solubility (preferably 0.5 to 2). (Concentration by weight), that is, a concentrator 18 that makes a fullerene concentration concentrate (L) of 3.6 to 108.0 g / L (preferably 9.0 to 36.0 g / L). The concentrator 18 is provided with a heating means (not shown) for heating the first extract (C) and a decompression means (not shown) for reducing the pressure inside the concentrator 18, so that the TMB in the first extract (C) ( B alone or B + G) is heated to evaporate under reduced pressure, and the first extract (C) is concentrated to obtain a concentrate (L). Here, the evaporated TMB (B + G) is stored again in the organic solvent tank 13 and reused.

Further, the fullerene production apparatus 10 is isopropyl alcohol (isopropyl alcohol, hereinafter referred to as IPA (M )) Is stored in the poor solvent tank 19. Here, IPA has a C60 solubility of about 0.007 g / L. Further, the fullerene production apparatus 10 mixes the concentrate (L) supplied from the concentrator 18 and the IPA (M) supplied from the poor solvent tank 19 to precipitate insoluble fullerene in the IPA (M). A crystallization tank 20 is provided. IPA (M) is mixed in an amount of 0.1 to 20 times by weight, preferably 1 to 20 times by weight, with respect to the concentrate (L). In addition, although the addition method of a poor solvent is arbitrary, adding gradually is preferable.

Here, a third slurry (O) having TMB (B + G) and IPA (M) and fullerene precipitates (N) is obtained by adding the poor solvent into the crystallization tank 20. The fullerene production apparatus 10 includes a third continuous pressure filter 21 that is an example of an apparatus for separating the third slurry (O). The fullerene precipitate (N) is filtered from the third slurry (O) with the third continuous pressure filter 21.

Furthermore, the fullerene production apparatus 10 includes a first conical ribbon agitation dryer 22 that dries the fullerene precipitate (N), and the first conical ribbon agitation dryer 22 causes the fullerene precipitate (N ) To remove TMB (B + G) and IPA (M) to obtain fullerene (P).

The fullerene production apparatus 10 includes a vacuum distillation unit 23 for fractionating TMB (B + G) and IPA (M) removed by the third continuous pressure filter 21 and the first conical ribbon agitation dryer 22, respectively. The pressure is reduced to 1000 to 30000 Pa, for example, 3000 Pa, heated at 55 ° C. to fractionate IPA (M), and further heated to 127 ° C. to fractionate TMB (B + G). The fractionated TMB (B + G) is stored again in the organic solvent tank 13 and the IPA (M) is stored again in the poor solvent tank 19 for reuse.

The fullerene production apparatus 10 removes TMB (B + G) from the second residue (K), and obtains the soot residue (Q) contained in the second insoluble substance (I) as a solid. A stirring dryer 24 is provided. The TMB (B + G) removed by the second conical ribbon agitation dryer 24 is stored again in the organic solvent tank 13 and reused.
The residue (Q) has a carbon content by elemental analysis of usually 90% by weight or more, preferably 98% by weight or more. Like carbon black, for example, functional groups such as hydroxyl groups and carboxyl groups A carbon material containing a small amount of. This carbon material is a useful material having an amorphous structure, a low true density, high resistance, excellent chargeability, and low thermal conductivity.

(Example 1)
In the fullerene production apparatus 10, toluene and pure oxygen, which is an example of a carbon-containing compound, are mixed in a gas phase with a molar ratio of 1: 3 in a combustion furnace 12, and toluene is incompletely burned at 5.32 kPa. A material (A) was obtained. The fullerene content in the rod-like substance (A) was measured by high performance liquid chromatography. As a result, the rod-like substance (A) contained 18.0% by weight of fullerene mainly composed of C60.

300 kg of this soot-like substance (A) (including 54 kg of fullerene. The remainder is carbon-based polymer (residue of soot)) and 4000 kg of TMB (B) are fed into the first extraction tank 14 at 40 ° C. for 30 minutes. Mixing while stirring with a stirring blade. In the first extraction tank 14, the fullerene in the bowl-shaped substance (A) is dissolved in TMB (B), and the first insoluble substance (D) such as a carbon-based polymer in the bowl-like substance (A) is A first slurry (E) composed of the first extract (C) and the first insoluble substance (D) in which fullerene is dissolved is obtained without being dissolved in TMB (B).

Next, the obtained first slurry (E) is filtered with the first extract (C) of about 3000 kg by the first continuous pressure filter 15 having a filtration area of 1 m ² , and the first And the first residue (F) made of the first insoluble substance (D) to which a part of the extract (C ′) is attached.
The first residue (F) contains about 250 kg of insoluble components in the filtered first insoluble substance (D), that is, the bowl-like substance (A), and this first insoluble substance (F) 4 to 5 times the weight of D), that is, approximately 1000 to 1250 kg of the first extract (C ′) is attached and contained. In addition, about 3000 kg of the first extract (C) was obtained.

Here, in order to collect the fullerene in the first extract (C ′) adhering to the first insoluble substance (D), the first residue (F) is put into the second extraction tank 16. Then, 3000 kg of TMB (G) was supplied to the second extraction tank 16 and mixed while stirring with a stirring blade at 40 ° C. for 30 minutes. In the second extraction tank 16, the first residue (F) and TMB (G) are mixed, and the second extraction liquid (H) and the second insoluble substance (I) insoluble in TMB are formed. A second slurry (J) is obtained. Further, the second slurry-like material (J) is filtered from the second slurry-like material (J) by the second continuous pressure filter 17 having a filtration area of 1 m ^2. Thus, approximately 3000 kg of the second extract (H) is obtained.

This second extract (H) 3000 kg is supplied to the first extraction tank 14, and 300 kg of the soot-like substance (A) is newly supplied from the soot-like substance tank 11. Further, since the amount of TMB was substantially small relative to the rod-like substance (A), 1000 kg of TMB (B) was supplied from the organic solvent tank 13 to the first extraction tank 14. In addition, these operation was performed 4 times similarly to the above-mentioned 1st-4th process, 1500 kg of soot-like substances were processed as a total quantity, and 15000 kg of 1st extract (C) was obtained.

15000 kg of the first extract (C) obtained as described above is supplied to the concentrator 18, the inside of the concentrator 18 is set to 80 ° C. and 5.3 kPa, and the first extract (C) is concentrated about 2 times by weight. To obtain 7500 kg of concentrated liquid (L). As a result of measurement by high performance liquid chromatography, the concentrated liquid (L) contained 3.3 wt%, that is, 247.5 kg of fullerene. Further, about 14750 kg of TMB (B + G) removed by the concentrator 18 can be supplied to the organic solvent tank 13 and reused.

Next, 2500 kg of the concentrated liquid (L) 7500 kg was supplied to the crystallization tank 20, and the inside of the crystallization tank 20 was adjusted to 50 ° C. Further, 10000 kg of IPA (M) was gradually added to the crystallization tank 20 over 3 hours and mixed while stirring with a stirring blade. By adding IPA (M) into the crystallization tank 20, a third slurry (O) having TMB (B + G) and IPA (M) and fullerene precipitates (N) is obtained. This operation was performed twice more, and the remaining 5000 kg of concentrated liquid (L) was processed.

The obtained third slurry (O) is separated by a third continuous pressure filter 21 having a filtration area of 0.7 m ² to obtain a fullerene precipitate (N). Further, this fullerene precipitate (N) was dried at 130 ° C. and 0.3 kPa for 25 hours by the first conical ribbon agitation dryer 22, and TMB (B + G) and IPA adhered to the fullerene precipitate (N) (M) is removed to obtain 247.0 kg of solid fullerene (P). The recovery rate from fullerene (54 kg × 5 = 270 kg) contained in the initial soot-like substance (A) was 91.5%.

The TMB (B + G) and IPA (M) removed by the third continuous pressure filter 21 and the first conical ribbon agitation dryer 22 are reduced to a pressure of 3000 Pa by the vacuum distillation unit 23, and 55 IPA (M) was fractionally distilled by heating at 0 ° C., and further heated to 127 ° C. to fractionate TMB (B + G). The fractionated TMB (B + G) is stored again in the organic solvent tank 13 and the IPA (M) is stored again in the poor solvent tank 19 for reuse. In Example 1, the amount of TMB supplied from the organic solvent tank 13 was 23000 kg.

Further, the second residue (K) separated by the second continuous pressure filter 17 is dried at 180 ° C. and 0.3 kPa for 30 hours by the second conical ribbon agitation dryer 24, About 1250 kg was obtained with the soot residue (Q) contained in the insoluble material (I) as a solid. The soot residue (Q) has a carbon content of 90% by weight or more by elemental analysis, and has a carbon material containing a small amount of functional groups such as a hydroxyl group and a carboxyl group, for example, like carbon black. This carbon material is a useful material having an amorphous structure, low true density, high resistance, excellent chargeability, and low thermal conductivity. The TMB (B + G) removed by the second conical ribbon agitation dryer 24 is stored again in the organic solvent tank 13 and can be reused.

(Comparative Example 1)
In the fullerene production apparatus 10, the second extract (H) separated by the second continuous pressure filter 17 is not used as the first organic solvent in the first step, and the TMB (B ), And 300 kg of the soot-like substance (A) was collected five times, that is, the fullerene was recovered from a total amount of 1500 kg (inner fullerene 270 kg). The recovered fullerene was 250 kg, and the recovery rate was 92.6% by weight. The amount of TMB supplied from the organic solvent tank 13 was 35000 kg, which was about 1.5 times that of Example 1 was supplied. Therefore, the amount of the first extract (C) supplied to the concentrator 18 is increased, and the power, time, etc. when concentrating the first extract are higher than in the first embodiment.

The present invention is not limited to the above-described embodiment, and can be changed without changing the gist of the present invention. For example, some or all of the above-described embodiments and modifications are possible. The combination of the above to constitute the fullerene production method of the present invention is also included in the scope of the present invention.

For example, in the fullerene production method of the above-described embodiment, the first and second organic solvents are TMB. However, it is sufficient that the fullerene is soluble, and a solvent having a C60 solubility of 1 g / L or more is preferable. In addition, o-xylene and toluene are preferably used. Further, although the poor solvent is IPA, it is sufficient that fullerene is insoluble or hardly soluble, and the solubility of C60 is preferably 0.1 g / L or less, such as methanol, ethanol, n-propanol, ethylene glycol, glycerin, etc. Of these, isopropanol and methanol are preferable, and methanol is particularly preferable.

In the above embodiment, a continuous pressure filter is used to separate the first and second slurry substances, but a vacuum filter and a centrifuge can be used, and these can be used in combination. In addition to the pressure filter, a vacuum filter or both can be used to collect fullerene in the poor solvent. In addition, since a part of the second extract in which fullerene is dissolved adheres to the second residue, an organic solvent is mixed with the second residue to recover the fullerene in the second residue. Further, the residue generated after the recovery may be mixed with an organic solvent, and the fullerene remaining on the residue may be extracted and recovered.

After fractionating TMB and IPA with a vacuum distillation apparatus, since fullerene dissolved in TMB and IPA remains, supply the remaining fullerene to a concentrator or a crystallization tank. Fullerenes can also be recovered. In this embodiment, two extraction tanks are provided. However, three or more extraction tanks may be provided to improve the fullerene recovery rate. Moreover, although fullerene is manufactured by a batch type, it is good also as a continuous type.

In addition, the fullerene-containing substance may be contacted with a fullerene-containing organic solvent to extract the fullerene in the soot-like substance, and the fullerene in the soot-like substance may be recovered. In this case, the organic solvent containing fullerene can be reused.

It is explanatory drawing of the fullerene manufacturing apparatus to which the manufacturing method of fullerene which concerns on one embodiment of this invention is applied.

Explanation of symbols

10: Fullerene production apparatus, 11: bowl-shaped material tank, 12: combustion furnace, 13: organic solvent tank, 14: first extraction tank, 15: first continuous pressure filter, 16: second extraction Tank: 17: second continuous pressure filter, 18: concentrator, 19: poor solvent tank, 20: crystallization tank, 21: third continuous pressure filter, 22: first conical ribbon stirrer Dryer, 23: vacuum distiller, 24: second conical ribbon stirring dryer

Claims (11)

A method for producing fullerene, comprising: bringing a soot-like substance containing fullerene into contact with an organic solvent containing fullerene to extract fullerene in the soot-like substance. A first step of obtaining a first slurry by mixing a soot-like substance containing fullerene and a first organic solvent;
A second step of separating the first slurry to obtain a first extract solution and a first residue in which fullerene is dissolved;
A third step of mixing the first residue and the second organic solvent to obtain a second slurry,
A fourth step of separating the second slurry and obtaining a second extract solution and a second residue in which fullerene is dissolved,
A method for producing fullerene, characterized in that the second extract is used for all or part of the first organic solvent after the second time. 3. The fullerene production method according to claim 2, wherein the soot-like substance is obtained by combustion or thermal decomposition of a carbon-containing compound. 4. The fullerene production method according to claim 2, wherein the first and second organic solvents have a C60 solubility of 1 g / L or more. 5. 5. The method for producing fullerene according to claim 2, wherein the first organic solvent is mixed in an amount of 4 to 200 times by weight with respect to a weight of the soot-like substance. Fullerene production method. The fullerene production method according to any one of claims 2 to 5, wherein one or both of the first and second slurry-like materials are separated by a vacuum filter, a pressure filter, and a centrifuge. A method for producing fullerene, which is performed by any one or more of the separators. The method for producing fullerene according to any one of claims 2 to 6, wherein the first extract is concentrated to 0.2 to 6 with respect to the solubility of the first and second organic solvents. A method for producing fullerene, characterized in that a concentrate having a concentration of fullerene in an amount by weight is obtained. The fullerene production method according to claim 7, wherein the concentrated solution and a poor solvent in which fullerene is insoluble or hardly soluble are mixed, and fullerene insoluble in the poor solvent is precipitated. 9. The method for producing fullerene according to claim 8, wherein the poor solvent is a polar solvent having a C60 solubility of 0.1 g / L or less. 10. The method for producing fullerene according to claim 8, wherein the poor solvent is mixed in an amount of 0.1 to 20 times by weight with respect to the concentrated solution. 11. . The fullerene production method according to any one of claims 8 to 10, wherein the fullerene in the poor solvent is recovered using one or both of a pressure filter and a vacuum filter. Manufacturing method.

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