JP2004099380A - Method for isolating C60 - Google Patents

Abstract

A method for producing C60 in large quantities and with high purity is provided.
A method of separating C60 from a mixture of fullerenes containing at least C60 and C70, wherein activated carbon having an integrated pore volume of pores having a diameter of 2 nm or less of 0.3 cm ³ / g or more is used. Isolation method.
[Selection diagram] None

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for isolating fullerenes, which are new carbon materials, and in particular, fullerenes having a molecular structure of C60.
[0002]
[Prior art]
In 1990, a new type of molecular carbon material called a closed-shell structure-type carbon cluster (spherical macromolecule) having 60, 70, 84 carbon atoms was synthesized and attracted attention. Carbon clusters having this special molecular structure are also called fullerenes, and are called fullerenes C60, C70, C84, etc., depending on the number of carbons constituting the molecular skeleton (simply C60, C70, C84, etc.). Also called.) Since these fullerenes are new carbon materials and are expected to exhibit unique physical properties due to their special molecular structures, studies on their properties and application development are being actively pursued. Fullerenes are expected to be used in fields such as diamond coatings, battery materials, paints, heat insulating materials, lubricants, and cosmetics.
[0003]
The method for producing fullerenes includes (1) a method in which 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 (arc discharge method), and (2) a high current is applied to the carbonaceous raw material. (3) a method of evaporating a carbonaceous material by irradiating a high energy density pulse laser (laser evaporation method), and (4) a method of incompletely burning organic substances such as benzene. (Combustion method) and the like are known. However, at present, it is not possible to produce only the desired single fullerenes or useful C60-C84 fullerenes by any of the production methods, and a mixture of a plurality of fullerenes, mainly C60 and C70, and many other carbon compounds. (This combustion product is sometimes referred to as “soot”). The content of fullerenes in soot is about 10 to 30% even in the arc discharge method which is said to be efficient, and the generation ratio of C70: C60 is about 1:10. Therefore, in order to obtain high-purity fullerene, it is necessary to first separate only fullerenes from soot.
[0004]
As a method of separating fullerenes from combustion products "soot", (1) fullerenes are dissolved in organic solvents such as benzene, toluene and carbon disulfide, and the other impurity components are hardly dissolved. A method of extracting fullerenes from soot using such an organic solvent (solvent extraction method) and a method of sublimating fullerenes by heating the soot under high vacuum (sublimation method) are known. . Of these, the sublimation method is a special separation method that requires high vacuum conditions of, for example, a high temperature of 400 ° C. or more and a pressure of 0.133 Pa (10 ⁻³ Torr) or less. Widely used. Furthermore, for separation of single fullerenes from a solution containing fullerenes (mainly a mixture of C60 and C70) obtained by extraction, methods such as column chromatography separation, fractional recrystallization, and inclusion of fullerenes are applied. .
[0005]
In the case of producing fullerenes by a combustion method, when an organic substance such as toluene is incompletely burned under controlled conditions, a soot-like substance containing a plurality of fullerenes mainly composed of C60 and C70 is generated (for example, Patent Document 1). 1). Typically, soot-like substances usually contain about 10 to 30% by weight of fullerenes and 10 ppm to 5% by weight of polycyclic aromatic hydrocarbons. The residue is a carbon having a graphite structure, a high molecular hydrocarbon having a graphite structure as a skeleton and having a small number of hydrogen atoms, carbon black, or the like (hereinafter, may be referred to as a “carbon-based polymer component”).
[0006]
Comparing the solubility of fullerenes and polycyclic aromatic hydrocarbons in a solvent, the solubility of polycyclic aromatic hydrocarbons is usually at least 10 times higher. Therefore, when a soot-like substance is extracted with a solvent, it is difficult to selectively extract only fullerenes, and polycyclic aromatic hydrocarbons in the soot-like substance are almost simultaneously extracted into the extract. For this reason, the solid obtained by concentrating and drying the extracted liquid, or filtering and drying the solid content precipitated is usually about 0.01 to 10% containing polycyclic aromatic hydrocarbons. You will get fullerenes.
[0007]
As a large number of carbides, there are polycyclic aromatic hydrocarbons represented by benzopyrene. Polycyclic aromatic hydrocarbons have a structurally low proportion of hydrogen atoms among hydrocarbons, and are structurally similar to fullerenes. Therefore, when mixed with fullerenes, the reactivity of fullerenes And may also block the intrinsic properties of fullerenes. It is considered that it is necessary to reduce these polycyclic aromatic hydrocarbons as much as possible from the viewpoint of safety.
[0008]
Further, fullerenes are a mixture of several kinds having different carbon numbers, and since their properties are different depending on the carbon number, it is desired to provide a single kind of compound having high purity. However, it has been difficult to produce high-purity fullerene species in large quantities by the conventional production method. In addition, a method of separating fullerene using activated carbon has been conventionally known (for example, see Patent Literatures 2 and 3), but a method of more efficiently isolating C60 has been demanded.
[0009]
[Patent Document 1]
US Patent No. 5,273,729 [Patent Document 2]
US Patent No. 5,310,532 [Patent Document 3]
U.S. Pat. No. 5,662,876.
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a production method capable of efficiently producing C60 in high purity and in large quantities from a soot-like substance containing fullerenes and polycyclic aromatic hydrocarbons. .
[0011]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in view of the circumstances described above. As a result, they have found that high-purity C60 can be efficiently isolated from a mixture of fullerenes by using a specific activated carbon, and have reached the present invention.
[0012]
That is, the gist of the present invention is that in a method of separating C60 from a mixture of fullerenes containing at least C60 and C70, an activated carbon having an integrated pore volume of pores having a diameter of 2 nm or less of 0.3 cm ³ / g or more is used. The present invention resides in a method for isolating C60 which is a feature.
[0013]
Another gist of the present invention is that (step A) heating a soot-like substance containing fullerenes, a polycyclic aromatic hydrocarbon, and a carbon-based polymer substance under an inert gas to produce a polycyclic aromatic hydrocarbon (B) a step of mixing a soot-like substance containing fullerenes and a carbon-based polymer substance with an extraction solvent to obtain an extract in which fullerenes are dissolved, Step C) The method for isolating C60, comprising the step of isolating C60.
[0014]
Another aspect of the present invention is that a soot-like substance containing fullerenes, polycyclic aromatic hydrocarbons, and a carbon-based polymer substance is obtained by burning and / or pyrolyzing a hydrocarbon compound. The present invention relates to the method for isolating C60.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
The mixture of fullerenes containing at least C60 and C70 applied to the method for isolating C60 of the present invention (hereinafter, may be simply referred to as “mixture of fullerenes”) may be obtained by any method. Is also good. In order to produce fullerenes in large quantities, it is preferable to use a combustion method in which the hydrocarbon raw material is incompletely burned, or a thermal decomposition method in which the hydrocarbon raw material is decomposed under high heat, and the combustion method is particularly preferable.
[0016]
When producing fullerene by a combustion method, the pressure condition is preferably 1330 to 13300 Pa (10 to 100 Torr), and more preferably 3990 to 6650 Pa (30 to 50 Torr). The temperature condition is preferably from 800 to 2500C, more preferably from 1000 to 2000C.
As a raw material of fullerene, an aromatic hydrocarbon having 6 to 15 carbon atoms such as benzene, toluene, xylene, naphthalene, methylnaphthalene, anthracene, and phenanthrene is preferably used. As a raw material, aliphatic hydrocarbons such as hexane, heptane, and octane may be used in combination with these aromatic hydrocarbons.
[0017]
In the combustion method, the raw material of fullerene simultaneously acts as a heat source. That is, the raw hydrocarbon reacts with oxygen to generate heat and raises to a temperature at which fullerene can be generated, and the raw hydrocarbon is dehydrogenated to generate carbon units for forming a fullerene skeleton. Is considered one. The carbon units assemble under certain pressure and temperature conditions to form fullerenes.
[0018]
The amount of oxygen used varies slightly depending on the type of the raw material hydrocarbon. For example, when toluene is used as the raw material hydrocarbon, the amount is preferably 0.5 to 9 times, more preferably 1 to 5 times the amount of toluene. Is more preferred.
In addition to oxygen, the reaction system in the combustion method may contain a gas that is inert to fullerene. Examples of these inert gases include helium, neon, argon, nitrogen, carbon dioxide and the like.
[0019]
The soot-like substance obtained by the combustion method contains fullerenes and polycyclic aromatic hydrocarbons, and the rest is a high molecular weight hydrocarbon generally having a carbon graphite structure and some hydrogen atoms. And carbon-based polymer components such as carbon black.
The soot-like substance preferably contains 5% by weight or more of fullerenes, more preferably 10% or more, and particularly preferably 15% or more.
The fullerenes produced by the present invention are not limited in carbon number as long as they have a fullerene structure, but are usually fullerenes having 60 to 84 carbon atoms. It is preferably at least 50%, more preferably at least 70%, particularly preferably at least 80%.
[0020]
When a mixture of fullerenes is produced by a combustion method or a pyrolysis method in order to apply to the method for isolating C60 of the present invention, fullerenes and polycyclic aromatic carbonized products produced by the combustion method or the pyrolysis method. A step (Step A) of first heating a soot-like substance containing hydrogen and a carbon-based polymer component under an inert gas to sublime polycyclic aromatic hydrocarbons and separate the polycyclic aromatic hydrocarbon from the soot-like substance is performed. .
[0021]
(Step A)
The conditions for subliming polycyclic aromatic compound, the pressure is preferably from 100 to 2 × ¹⁰ 5 Pa, more preferably 1000~1.4 × ¹⁰ 5 Pa. At normal pressure, there is an advantage that the apparatus is simplified, and under reduced pressure, there is an advantage that the sublimation temperature of the polycyclic aromatic hydrocarbon is reduced. It is sufficient to carry out the process under optimal conditions in consideration of economy. The temperature is preferably 100 ° C. or more and 800 ° C. or less. The sublimation temperature varies depending on the pressure, and may be appropriately selected. In the case of normal pressure, the temperature is preferably 200 to 700 ° C, more preferably 300 to 600 ° C. If the temperature is too low, the sublimation of the polycyclic aromatic hydrocarbon becomes insufficient, and if the temperature is too high, the fullerenes also sublime, and the recovery of fullerenes decreases.
[0022]
The apparatus used for sublimation is not particularly limited, such as a batch type, a fixed bed type, a fluidized bed type, and a continuous type, as long as it can withstand the above-described sublimation conditions at the temperature / pressure. Materials used for the sublimation apparatus include quartz glass, metals such as stainless steel, ceramics, and glass.
The sublimation is performed in the presence of an inert gas. In the present invention, the inert gas means a gas that does not substantially react with fullerenes under the sublimation temperature / pressure conditions. Types of inert gases include helium, neon, argon, nitrogen and mixtures thereof. In order to avoid the reaction of fullerenes, the sublimation apparatus is substantially replaced with an inert gas during sublimation, and the oxygen content in the gas in the sublimation apparatus is preferably 10% by volume or less, preferably 5% by volume. %, Preferably 1% by volume. When the content of oxygen is large, oxides of fullerenes may be generated.
[0023]
Further, the sublimation of the polycyclic aromatic hydrocarbon is preferably performed under a flow of an inert gas. As a method performed under the flow of the inert gas, for example, an inlet and an outlet for the inert gas are provided in the sublimation apparatus, and the temperature is increased to a predetermined temperature while continuously flowing the inert gas. . The inert gas may be preheated when flowing into the sublimation apparatus.
[0024]
The flow rate of the inert gas when sublimating under the flow of the inert gas is preferably 1 to 10000 ml / min, more preferably 5 to 5000 ml / min per 1 g of the soot-like substance. The flow of the inert gas may be continuous or intermittent.
[0025]
The polycyclic aromatic hydrocarbon sublimated from the sublimation device is entrained by the inert gas, and the temperature is reduced by the deposition device, whereby the polycyclic aromatic hydrocarbon can be precipitated. The precipitation apparatus may be provided in the same apparatus as the sublimation apparatus or may be provided separately, and may be a batch type or a continuous type. The recovered polycyclic aromatic hydrocarbon may be collected mechanically or collected, or may be dissolved in a solvent and collected. The inert gas after the polycyclic aromatic hydrocarbon is precipitated and recovered is released to the atmosphere or recycled. The operation time varies depending on the temperature, pressure and gas flow rate, but is usually about 10 minutes to 12 hours.
[0026]
(Step B)
Next, the soot-like substance containing the carbon-based polymer component and the fullerenes from which the polycyclic aromatic hydrocarbons have been separated is mixed with an extraction solvent to obtain an extract in which the fullerenes are dissolved. The carbon-based polymer component does not substantially dissolve in the extraction solvent. As the extraction solvent, a solvent containing an aromatic hydrocarbon is preferably used.
The aromatic hydrocarbon used as the extraction solvent is a hydrocarbon compound having at least one benzene nucleus in the molecule, and specifically, 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-tetramethyl Examples thereof include alkylbenzenes such as benzene, 1,2,3,5-tetramethylbenzene, diethylbenzene and cymene; alkylnaphthalenes such as 1-methylnaphthalene; and tetralin. Of these, 1,2,4-trimethylbenzene and tetralin are preferred.
[0027]
As the extraction solvent, in addition to the aromatic hydrocarbon, an organic solvent such as an aliphatic hydrocarbon or a chlorinated hydrocarbon may be used alone, or two or more of them may be used at an arbitrary ratio. As the aliphatic hydrocarbon, any aliphatic hydrocarbon such as cyclic and acyclic can be used. Examples of the cycloaliphatic hydrocarbon include monocyclic aliphatic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane and cyclooctane, and derivatives thereof such as methylcyclopentane, ethylcyclopentane, methylcyclohexane, ethylcyclohexane, and the like. , 2-dimethylcyclohexane, 1,3-dimethylcyclohexane, 1,4-dimethylcyclohexane, isopropylcyclohexane, n-propylcyclohexane, t-butylcyclohexane, n-butylcyclohexane, isobutylcyclohexane, 1,2,4-trimethylcyclohexane, Examples include 1,3,5-trimethylcyclohexane, and polycyclic decalin. Examples of acyclic aliphatic hydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, isooctane, n-nonane, n-decane, n-dodecane, n-tetradecane, and the like.
[0028]
Examples of the chlorinated hydrocarbon include dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, dichlorobenzene, 1-chloronaphthalene and the like.
Other examples include ketones having 6 or more carbon atoms, esters having 6 or more carbon atoms, ethers having 6 or more carbon atoms, and carbon disulfide.
[0029]
When the solubility of the fullerene as the extraction solvent is too low, the extraction efficiency is reduced. Therefore, the solubility of the fullerene is preferably 5 g / L or more, more preferably 10 g / L or more, and particularly preferably 15 g / L or more. From the industrial viewpoint, among these extraction solvents, those having a normal temperature liquid and a boiling point of 100 to 300 ° C., particularly preferably 120 to 250 ° C., are preferable.
[0030]
It is necessary to use an extraction solvent in an amount sufficient to extract fullerenes. Usually, the amount of the fullerenes in the soot-like substance is preferably 5 to 400 times by weight, and considering economical efficiency, it is preferable to use about 40 to 200 times by weight. The type and apparatus for the extraction are not particularly limited, such as a batch type, a semi-continuous type, a continuous type, or a combination thereof.
The soot-like substance usually contains 5 to 30% by weight of fullerenes, but from the viewpoint of extraction efficiency, the amount of the extraction solvent used for the fullerenes is preferably in the above range, Prior to the extraction operation, it is preferable to analyze a part of the soot-like substance and measure the fullerene content in the soot-like substance.
[0031]
The soot-like substance usually contains 5 to 30% by weight of fullerenes, but from the viewpoint of extraction efficiency, the amount of the extraction solvent used for the fullerenes is preferably in the above range, Prior to the extraction operation, it is preferable to analyze a part of the soot-like substance and measure the fullerene content in the soot-like substance.
[0032]
(Step C)
Since the extract thus obtained contains C60, C70 and higher fullerenes having a carbon number higher than that, C60 is isolated from the fullerene mixture by treating with activated carbon.
When treating fullerenes with activated carbon, it is preferable to use an eluent containing an aromatic hydrocarbon compound, but the solvent of the extract may be used as it is, or a part or all of the extract may be used. It may be distilled off and replaced with another eluent.
[0033]
The activated carbon used in the present invention has a cumulative pore volume of pores having a diameter of 2 nm or less of 0.3 cm ³ / g or more. This activated carbon has a relatively small adsorptive power for C60 and a relatively high adsorptive power for C70 or higher fullerenes, and thus has an excellent ability to separate C60 and C70 or higher fullerenes. C60 can be isolated.
If the cumulative pore volume of the pores having a diameter of 2 nm or less is 0.3 cm ³ / g or less, the ability to adsorb fullerenes is low, and it becomes difficult to separate C60 and higher fullerenes of C70 or more. The cumulative pore volume of pores having a diameter of 20 ° or less is preferably 0.4 cm ³ / g or more, and more preferably 0.5 cm ³ / g or more. The upper limit is not particularly defined, but is usually 10 cm ³ / g or less.
[0034]
Further, the specific surface area of the activated carbon is preferably 1600 m ² / g or more, more preferably 2000 m ² / g or more, and particularly preferably 2500 m ² or more. When the specific surface area is within the above range, the processing capacity of fullerenes per time is increased.
Furthermore, the activated carbon preferably has a ratio of particles having a particle size of 30 μm or less of 40% or less, more preferably 30% or less, and particularly preferably 25% or less. When the proportion of activated carbon having a small particle size of 30 μm or less is within the above range, the operation of treating a mixture of fullerenes becomes easy.
[0035]
When treating fullerenes with activated carbon, it is preferable to use an eluent containing an aromatic hydrocarbon compound. As the aromatic hydrocarbon compound, those similar to those used in the step B are used. In order to efficiently separate C60 in large quantities, it is preferable to use a solution having a high solubility of fullerene and to treat a solution as concentrated as possible. The solubility of fullerene is preferably 5 g / L or more, more preferably 10 g / L or more. It is particularly preferable to use the one having 15 g / L or more. Among them, 1,2,4-trimethylbenzene and tetralin are preferred.
[0036]
As a method of treating with activated carbon, specifically, (a) a method in which a mixture of fullerenes is adsorbed on activated carbon, an eluent is mixed with the mixture, followed by filtration to elute C60 in the eluate, or ( b) A method in which a column is filled with activated carbon as a filler, fullerenes are placed on the column, and then an eluent is flowed. These treatment methods can be appropriately selected according to the adsorption power of activated carbon.
[0037]
In the fullerenes subjected to the activated carbon treatment, the compound species of C60 is preferentially dissolved in the developing solvent, and thus, high-purity C60 is isolated by distilling the developing solvent by a method such as heating and decompression. Can do things. The purity of C60 is usually 95% or more, preferably 97% or more, and more preferably 98% or more.
[0038]
【Example】
Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.
(Example 1)
75 g of a soot-like substance produced by the combustion method and 1500 mL of 1,2,4-trimethylbenzene (TMB) were mixed at room temperature in a 2 L Erlenmeyer flask, and immersed in an ultrasonic cleaner for 30 minutes. The slurry was subjected to pressure filtration with nitrogen at a pressure of 2 kgG using a pressure filtration device manufactured by ADVANTEC, using a membrane filter of diameter 142 mm, made of PTFE, made of PTFE, and 0.5 μm. Of the filtrate, 118 g was concentrated to 90 g at 90 ° C. and 20 Torr using an evaporator manufactured by Buch. The above liquid was put into a 500 cc separable flask, and stirred with a rotary blade. After the temperature was raised to 50 ° C., 125 g of THF was added by a pump over 60 minutes while maintaining the temperature. It was kept for 10 minutes after the addition. The solution was in a slurry state. This slurry was filtered under reduced pressure using a 0.5 μm membrane filter made of PTFE, 47 mm in diameter, manufactured by ADVANTEC, and after the filtration was completed, 50 mL of THF was further sprinkled and washed. The solids separated by filtration were dried using a vacuum dryer at 100 ° C. and 5 Torr or less. The fullerenes thus obtained had a purity of the fullerenes of 91.9% by weight and contained 289 ppm by weight of the polycyclic aromatic compound.
The analysis of fullerenes was performed using liquid chromatography, and the analysis of polycyclic aromatic hydrocarbons was performed using gas chromatography.
[0039]
(Preparation of activated carbon column)
Powdered activated carbon MAXSORB MSC30 (Kansai Thermochemical Co., Ltd.) (cumulative pore volume of pores having a diameter of 20 mm or less; 0.55 cm ³ / g, specific surface area 3,250 square meters / g; potassium hydroxide activation) is a sieve No. manufactured by Yamato Science Co., Ltd. . 95.1 g was weighed on a 286, and sieved in the air for 5 minutes at the strength of the scale 50 using a sieve shaker VSS-50 manufactured by Tsutsui Chemical Chemical Co., Ltd. and a sieve having an opening of 26 micrometers. , 49.5 g remained on the sieve and were transferred to a 1 L glass beaker. The same operation was further repeated twice while changing the amount weighed on the sieve, to obtain a total of 177.6 g of MAXSORB MSC30 remaining on the sieve. 0.2 g of MAXSORB MSC30, which is a commercial product, and MAXSORB MSC30 remaining on the sieve were each weighed and dispersed in water, and analyzed with a laser diffraction particle analyzer SALD-2000J manufactured by Shimadzu Corporation. The average particle size of the product was 82 μm and 94 μm, respectively. The ratio of particles having a particle size of 30 μm or less in the sieved residue was 13%.
[0040]
When the specific surface area of the commercially available MAXSORB MSC30 and the MAXSORB MSC30 remaining on the sieve were calculated by the BET multipoint method in the range of the relative pressure of 0.002 to 0.2, they were 2994 square meters per gram and 2990 square meters per gram, respectively. there were. When the pore volume was calculated from the amount of nitrogen adsorbed at a relative pressure of 0.93, the commercial product was 1.60 mL / g, and the sieve residue was 1.59 mL / g. 130 g of the sieved residue is transferred to another 1 L beaker, and while removing heat in a water bath at 22 ° C., 0.6 L of 1,2,4 trimethylbenzene (also called pseudocumene) manufactured by Maruzen Petrochemical Co., Ltd. is stirred for 5 minutes. Activated carbon slurry was prepared by adding the mixture slowly and slowly.
[0041]
A perforated plate was placed in the bottom flange of a SUS304 column (inner diameter of the column: 68 mm, height: 100 mm), and a PTFE membrane filter having a diameter of 68 mm and a pore diameter of 0.2 micron was placed on the perforated plate, and attached to the column body. It was fixed with screws. The upper flange portion was removed, 0.049 L of the activated carbon slurry was poured into the column main body, and suction suction was performed under reduced pressure from the bottom outlet, thereby forming an activated carbon bed while extracting trimethylbenzene in the slurry. Extract trimethylbenzene just before the top of the activated carbon bed rises above the liquid level, repeat the operation of adding slurry, create an activated carbon bed with a layer height of 98 mm, attach the perforated plate and the upper flange containing the membrane filter, and screw Fixed with. The volume of the activated carbon bed was 363 cm ³ . The column was attached to the liquid sending line.
[0042]
(Preparation of raw material liquid)
Fullerene (C60; 61%, C70; 24%, containing a trace amount of polycyclic aromatic hydrocarbons) obtained by the above combustion method is weighed into a raw material tank, 5 L of trimethylbenzene is charged, and a three-one motor with a stirring blade is attached. The mixture was stirred at a strength of 5 for 1 hour and thoroughly melted to obtain a raw material liquid. A 6 L trimethylbenzene raw material tank was attached to the liquid sending line. Subsequently, 15 L of trimethylbenzene was charged into the eluent tank and attached to the liquid sending line. Trimethylbenzene was replenished as needed because the remaining amount was decreasing.
[0043]
(Sending of raw material liquid)
After temporarily disconnecting the connection between the upper part of the column and the liquid sending line, the pump was driven to remove the air in the liquid sending line while feeding the raw material liquid. The pump was stopped and the top of the column was immediately connected to the liquid sending line.
A 2 L plastic tank was installed at the outlet at the bottom of the column so that the effluent could be collected. After the pump was driven to start feeding the raw material liquid, a colorless and transparent liquid flowed out from the outlet. When the outflow speed was set to 0.15 L / min, the pressure gauge indicated 0.2 MPa.
When 5 L of the raw material liquid was fed while changing the fraction every time the amount of the effluent became 2 L, 18 minutes later, the feed of the raw material liquid was started, and after flowing out about 2.7 L, the outflow of the C60 component started. It was confirmed that the color was purple.
[0044]
(Sending of eluent)
When the supply of 5 L of the raw material liquid was completed, that is, while the third fraction was being collected, the pump was stopped, the pump was replaced with a plastic tank for the next fraction, and the valve was switched to start the supply of the eluent. Here, 5 L of the raw material liquid was 13.8 times the volume VB of the activated carbon bed. The total amount V of the raw material liquid and the eluent with respect to the volume VB of the activated carbon bed, that is, V / VB, may be treated as an index of the amount of the effluent.
The fourth and subsequent fractions were collected while changing the fraction every time the amount of the effluent reached 2 L, and a total of 22 L of eluent was sent. When the collection of the 14th fraction was completed, the pump was stopped.
(Analysis and results)
From the results of the LC analysis of each fraction, the concentrations of the contained C60 oxide, C60 and C70 were calculated to obtain a chromatogram. Fullerenes having a higher molecular weight than C70 did not flow out. The chromatogram of each component is shown in FIG. The C60 recovery was calculated from the weight ratio of C60 contained in 5 L of the raw material solution to the total weight of C60 contained in each fraction, and was found to be 85.6%. The total sum of the C60 oxide, C70 and other components contained in each fraction was determined, and the purity of C60 when all the fractions were the same was calculated to be 97.7%.
[0046]
(Comparative Example 1)
Activated carbon, Shiratsagi specially made by Takeda Pharmaceutical Co., Ltd. (cumulative pore volume of pores having a diameter of 20 mm or less; 0.27 cm ³ / g, specific surface area 1,430 square meters / g; zinc chloride activated, 30 μm or less after sieving) An attempt was made to isolate and purify fullerene obtained by the combustion method in the same manner as in Example 1 except that the ratio of particles having a particle diameter of 15% was used. , A colorless transparent liquid flowed out, and then a reddish brown liquid flowed out. LC analysis of this effluent confirmed that C60 and C70 were mixed, and isolation with an activated carbon column was not possible.
[0047]
(Comparative Example 2)
The activated carbon was obtained by a combustion method in the same manner as in Example 1, except that a specially made Shirasagi manufactured by Takeda Pharmaceutical Co., Ltd. was used without sieving (46% of particles having a particle size of 30 μm or less). When an attempt was made to isolate and purify the fullerene, the pressure reached 20 atm or more 1 minute after the start of the feed of the raw material liquid, and the flow could not be continued further.
[0048]
(Comparative Example 3)
Fullerenes (C60; 61%, C70; 24%, including a trace amount of polycyclic aromatic hydrocarbons) containing the same fullerenes as described above, a fullerene preparative column manufactured by Nacalai Tesque Co., Ltd., a Cosmoseal bucky prep packed column (4. (6 mm, 250 mm in length), column separation was attempted using 18 mL of the raw material liquid used in Example 1 and 80 mL of trimethylbenzene, and a dark brown liquid flowed out following the outflow of a colorless and transparent liquid. . C60 and C70 could not be separated and recovered.
[0049]
【The invention's effect】
According to the present invention, it is possible to provide a method for producing C60 in large quantities and with high purity.

Claims (10)

A method for isolating C60 from a mixture of fullerenes containing at least C60 and C70, characterized in that activated carbon having an integrated pore volume of pores having a diameter of 2 nm or less of 0.3 cm ³ / g or more is used. Method. The method for isolating C60 according to claim 1, wherein a mixture of fullerenes is adsorbed on the activated carbon, and C60 is eluted with an eluent containing an aromatic hydrocarbon compound. The C60 isolation method according to claim 1, wherein a column using the activated carbon as a packing material is used, and an eluent containing an aromatic hydrocarbon compound is used. C60 Isolation method according to any one of claims 1 to 3 the specific surface area of the activated carbon is 1600 m ² / g or more. The method for isolating C60 according to any one of claims 1 to 4, wherein the proportion of the activated carbon having a particle size of 30 µm or less is 40% or less. The method for isolating C60 according to any one of claims 1 to 5, wherein the activated carbon has been activated with potassium hydroxide. The method for isolating C60 according to any one of claims 2 to 6, wherein the eluent contains 1,2,4-trimethylbenzene or tetralin. (Step A) A soot-like substance containing fullerenes, polycyclic aromatic hydrocarbons, and a carbon-based polymer substance is heated under an inert gas to sublimate the polycyclic aromatic hydrocarbons from the soot-like substance. A separating step, a step (B), a step of mixing a soot-like substance containing fullerenes and a carbon-based polymer substance and an extraction solvent to obtain an extract in which the fullerenes are dissolved, and a step (C). The method for isolating C60, comprising the step of isolating C60 according to any one of the above. The method for isolating C60 according to claim 8, wherein in step B, the extraction solvent contains 1,2,4-trimethylbenzene or tetralin. The C60 according to claim 8 or 9, wherein the soot-like substance containing fullerenes, polycyclic aromatic hydrocarbons, and a carbon-based polymer substance is obtained by burning and / or pyrolyzing a hydrocarbon compound. Isolation method.