JP3974049B2 - Method for isolating C70 - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a new carbon material, fullerenes, especially C₇₀The present invention relates to a method for isolating fullerene having a molecular structure of
[0002]
[Prior art]
In 1990, a new type of molecular carbon material called a closed-shell carbon cluster (spherical macromolecule) having 60, 70, 84 carbon atoms, etc. was synthesized and attracted attention. Carbon clusters having this special molecular structure are also called fullerenes, and depending on the number of carbons constituting the molecular skeleton, fullerene C₆₀, The same C₇₀, The same C₈₄Etc. (simply called C₆₀, C₇₀, C₈₄Etc.). Since these fullerenes are new carbon materials and are expected to exhibit unique physical properties due to their special molecular structure, research on their properties and application development has been actively promoted. Fullerenes are expected to be used in fields such as diamond coating, battery materials, paints, heat insulating materials, lubricants, and cosmetics.
[0003]
The production methods of fullerenes include (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) Method of evaporating carbonaceous material by laser irradiation with high energy density (laser evaporation method), (4) Method of incomplete combustion of organic substances such as benzene (Combustion method) is known. However, in any current production method, the target single fullerene or beneficial C₆₀~ C₈₄It is not possible to produce fullerenes alone.₆₀And C₇₀It is produced as a mixture of a plurality of fullerenes mainly composed of carbon and many other carbon compounds (this combustion product is sometimes called “soot”). The content of fullerenes in the soot is about 10 to 30% even in the arc discharge method, which is said to be efficient.₇₀: C₆₀The production ratio of is about 1:10. Therefore, in order to obtain high-purity fullerene, it is necessary to first separate only fullerenes from the soot.
[0004]
As a method of separating fullerenes from the combustion product “煤”, (1) Fullerenes are dissolved in organic solvents such as benzene, toluene, carbon disulfide and other impurities are not easily dissolved. , A method of extracting fullerenes from soot using such an organic solvent (solvent extraction method), and (2) a method of sublimating fullerenes by heating the soot under high vacuum (sublimation method) is known. . Among these, the sublimation method is, for example, a high temperature of 400 ° C. or higher and a pressure of 0.133 Pa (10^-3Torr) is a special separation method that requires the following high vacuum conditions, and the solvent extraction method is widely used because it is easier to operate. Furthermore, fullerenes obtained by extraction (mainly C₆₀And C₇₀For the separation of a single fullerene from a solution containing a mixture of the above, a method such as column chromatography separation, fractional recrystallization, inclusion of fullerene, or the like is applied.
[0005]
When producing fullerene by a combustion method, if organic matter such as toluene is incompletely burned under controlled conditions, C₆₀And C₇₀A soot-like substance containing a plurality of fullerenes mainly composed of the above is produced (see, for example, Patent Document 1). Typically, the soot-like substance usually contains about 10 to 30% by weight of fullerenes and 10 ppm to 5% by weight of polycyclic aromatic hydrocarbons. The remainder is carbon having a graphite structure and polymer hydrocarbon, carbon black or the like having a few hydrogen atoms with the graphite structure as a skeleton (hereinafter sometimes referred to as “carbon-based polymer component”).
[0006]
When the solubility of fullerenes and polycyclic aromatic hydrocarbons in a solvent is compared, the solubility of polycyclic aromatic hydrocarbons is usually 10 times or higher. Therefore, when extracting from a soot-like substance with a solvent, it is difficult to selectively extract only fullerenes, and polycyclic aromatic hydrocarbons in the soot-like substance are almost simultaneously extracted to the extract side. For this reason, the extracted liquid is concentrated and dried, or the solid content obtained by concentrating and separating the solid is filtered and dried. Usually, about 0.01 to 10% of polycyclic aromatic hydrocarbons are contained in the solid. You will get fullerenes.
[0007]
As many carbides, there are polycyclic aromatic hydrocarbons represented by benzopyrene. Polycyclic aromatic hydrocarbons are structurally similar to fullerenes in that they have a low proportion of hydrogen atoms among the hydrocarbons. Therefore, when they are mixed in fullerenes, the reaction of fullerenes There is also the possibility of inhibiting the sex and shielding the inherent properties of fullerene. Further, it is considered that these polycyclic aromatic hydrocarbons need to be reduced as much as possible from the viewpoint of safety.
[0008]
Further, although fullerenes are a mixture of several kinds having different carbon numbers, since their properties differ depending on the number of carbons, it is desired to provide a single compound species with high purity. However, it has been difficult to produce high-purity fullerene species in large quantities by conventional production methods. Moreover, although the method of isolate | separating fullerene using activated carbon is also known conventionally (for example, refer patent document 2, 3), C₇₀In addition, fullerenes having more and more carbon atoms have strong adsorptive power to activated carbon, and it has been difficult to elute and recover them under conventional conditions.
[0009]
[Patent Document 1]
US Pat. No. 5,273,729
[Patent Document 2]
US Pat. No. 5,310,532
[Patent Document 3]
US Pat. No. 5,662,876
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and it has been found that a mixture of fullerenes is efficiently purified in a high purity and in a large amount.₇₀It is an object of the present invention to provide an isolation method capable of isolating.
[0011]
[Means for Solving the Problems]
The present inventors have intensively studied in view of the circumstances as described above. As a result, by using a specific eluent, high purity C can be obtained from a mixture of fullerenes.₇₀And the present invention has been reached.
[0012]
[Means for Solving the Problems]
  In other words, this departureTomorrow, At least C₆₀And C₇₀A mixture of fullerenes containingActivated carbonAdsorb toIncludes aromatic hydrocarbon compounds with 10 or less carbon atomsWith eluent, C ₆₀ Is eluted from the activated carbon, and then an eluent containing an aromatic compound having a naphthalene skeleton or a skeleton in which 1 or 2 of carbon forming the naphthalene skeleton is replaced with nitrogen is used. ₇₀ EluteC characterized by₇₀In the isolation method.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
C of the present invention₇₀Applied to the isolation method of at least C₆₀And C₇₀The mixture of fullerenes containing (hereinafter sometimes simply referred to as “mixture of fullerenes”) may be obtained by any method. In order to produce fullerenes in large quantities, 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 is preferable, and the combustion method is particularly preferable.
[0014]
When producing fullerenes by the combustion method, the pressure condition is preferably 1330 to 13300 Pa (10 to 100 Torr), more preferably 3990 to 6650 Pa (30 to 50 Torr). As temperature conditions, 800-2500 degreeC is preferable and 1000-2000 degreeC is still more preferable.
As raw materials for fullerenes, aromatic hydrocarbons having 6 to 15 carbon atoms such as benzene, toluene, xylene, naphthalene, methylnaphthalene, anthracene and phenanthrene are preferably used. As a raw material, aliphatic hydrocarbons such as hexane, heptane, and octane may be used in combination with these aromatic hydrocarbons.
[0015]
In the combustion method, the fullerene raw material simultaneously acts as a heat source. That is, the raw material hydrocarbon reacts with oxygen and generates heat to raise the temperature at which fullerene can be generated, and the raw material hydrocarbon is dehydrogenated to generate a carbon unit for forming a fullerene skeleton. It is considered a thing. Carbon units aggregate under a certain pressure and temperature condition to form fullerenes.
[0016]
The amount of oxygen used is slightly different depending on the type of raw material hydrocarbon. For example, when toluene is used as the raw material hydrocarbon, it is preferably 0.5 to 9 times mol and 1 to 5 times mol with respect to toluene. Is more preferable.
In the reaction system in the combustion method, a gas inert to fullerene may be present in addition to oxygen. Examples of these inert gases include helium, neon, argon, nitrogen, carbon dioxide and the like.
[0017]
The soot-like substance obtained by the combustion method contains fullerenes and polycyclic aromatic hydrocarbons, and the remainder other than that is usually carbonized in a polymer having a carbon graphite structure and some hydrogen atoms. Carbon-based polymer components such as hydrogen and 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.
[0018]
In addition, the fullerenes produced according to the present invention are not limited in the number of carbons as long as they have a fullerene structure, but are usually fullerenes having 60 to 84 carbon atoms.₆₀And C₇₀The total proportion of all the fullerenes is preferably 50% or more, more preferably 70% or more, and particularly preferably 80% or more.
C₇₀In the mixture of fullerenes₇₀It is preferable that the ratio of C is as large as possible, but when producing fullerenes, C₇₀If the production ratio is too large, the overall yield of fullerenes tends to be low.₇₀Is preferably 10% to 50%, more preferably 15% to 40%.
[0019]
The mixture of fullerenes to be applied to the isolation method of the present invention is, for example, from a mixture containing a fullerene produced by the combustion method described above, a polycyclic aromatic hydrocarbon, and a carbon-based polymer component (saddle-like substance). A product obtained by removing the polycyclic aromatic hydrocarbon and the carbon-based polymer component in advance can be used.
Examples of the method for removing polycyclic aromatic hydrocarbons from the soot-like substance include, for example, a method for extracting and removing polycyclic aromatic hydrocarbons using a solvent having low solubility of fullerenes, and under an inert gas. There is a method of heating the soot-like substance and sublimating and removing the polycyclic aromatic hydrocarbon.
[0020]
In addition, as a method of removing the carbon-based polymer component from the soot-like substance, a method of extracting fullerenes using a solvent having a high solubility of fullerenes and, if necessary, separating insoluble carbon-based polymer components by filtration. Is mentioned.
Below, C₆₀And C₇₀As an example of a method for obtaining a mixture of fullerenes containing bismuth, polycyclic aromatic hydrocarbons are removed from submerged substances by sublimation (step A), and then fullerenes are separated from carbon-based polymer components by solvent extraction. (Step B) The method will be described.
[0021]
(Process A: Sublimation process)
As a condition for sublimating the polycyclic aromatic compound, the pressure is 100 to 2 × 10.^FivePa is preferred, 1000 to 1.4 × 10^FivePa is more preferable. At normal pressure, there is a merit that the device is simple, and under reduced pressure, there is a merit that the sublimation temperature of the polycyclic aromatic hydrocarbon is lowered. In view of economic efficiency, it may be carried out under optimum conditions. The temperature is preferably 100 ° C. or higher and 800 ° C. or lower. Since the sublimation temperature varies depending on the pressure, it may be appropriately selected. However, in the case of normal pressure, 200 ° C. or higher and 700 ° C. or lower is more preferable, and 300 ° C. or higher and 600 ° C. or lower is particularly preferable. When the temperature is too low, the sublimation of the polycyclic aromatic hydrocarbon is insufficient, and when the temperature is too high, the fullerenes are also sublimated, and the recovery rate of the fullerenes is lowered.
[0022]
The apparatus used for sublimation is not particularly limited as long as it can withstand the sublimation conditions at the temperature / pressure described above, such as a batch type, a fixed bed type, a fluidized bed type, and a continuous type. Examples of the material used for the sublimation apparatus include metals such as quartz glass and stainless steel, ceramics, and glass.
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 temperature / pressure conditions of sublimation. Examples of the inert gas 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 volumes. % Or less, preferably 1% by volume. When the oxygen content is high, oxides of fullerenes may be generated.
[0023]
The sublimation of the polycyclic aromatic hydrocarbon is preferably performed under an inert gas flow. As a method performed under the flow of inert gas, for example, an inert gas inlet and outlet are provided in a sublimation apparatus, and the temperature is raised to a predetermined temperature while continuously flowing in and out of the inert gas. . The inert gas can be preheated when flowing into the sublimation apparatus.
[0024]
The flow rate of the inert gas when sublimation is performed under the flow of the inert gas is preferably 1 to 10,000 ml / min, and more preferably 5 to 5000 ml / min, with respect to 1 g of the soot-like substance. The flow of the inert gas may be continuous or intermittent.
[0025]
The polycyclic aromatic hydrocarbons sublimated from the sublimation apparatus are entrained in the inert gas, and the polycyclic aromatic hydrocarbons can be precipitated by lowering the temperature in the precipitation apparatus. The deposition apparatus may be provided in the same apparatus as the sublimation apparatus or may be provided separately, or may be a batch type or a continuous type. The recovered polycyclic aromatic hydrocarbons may be collected by mechanical collection or dissolved in a solvent and recovered. The inert gas after depositing and collecting the polycyclic aromatic hydrocarbons is released into 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]
(Process B: Extraction process)
Next, the fullerenes from which the polycyclic aromatic hydrocarbons have been separated and the soot-like substance containing the carbon-based polymer component are mixed with an extraction solvent, and a step of obtaining an extract in which fullerenes are dissolved is performed. The carbon-based polymer component is not substantially dissolved 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. 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 aromatic hydrocarbons, organic solvents such as aliphatic hydrocarbons and chlorinated hydrocarbons may be used alone, or two or more of them may be used in an arbitrary ratio. As the aliphatic hydrocarbon, any aliphatic hydrocarbon such as cyclic or acyclic can be used. Examples of 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, 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 fullerene is too low as the extraction solvent, the extraction efficiency is lowered. Therefore, the solubility of fullerene is preferably 5 g / L or more, more preferably 10 g / L or more, and particularly preferably 15 g / L or more. Also, from an industrial viewpoint, among these extraction solvents, those having a normal temperature liquid and a boiling point of 100 to 300 ° C, particularly 120 to 250 ° C are preferable.
[0030]
As the extraction solvent, it is necessary to use an amount sufficient to sufficiently extract fullerenes. In general, it is preferable to use about 40 to 200 times the amount of the fullerenes in the rod-like substance, considering the amount of 5 to 400 times the amount and economy. There are no particular limitations on the type and apparatus of extraction, such as batch, semi-continuous, continuous, or combinations thereof.
In addition, although 5 to 30% by weight of fullerenes are usually contained in the rod-like substance, from the viewpoint of extraction efficiency, it is preferable to set the amount of the extraction solvent used for the fullerenes within 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]
(C₇₀Step of isolating
The extract thus obtained contains C₆₀, C₇₀, And higher order fullerene having a carbon number of at least that, an eluent containing an aromatic compound having a naphthalene skeleton or a skeleton in which one or two of the carbons forming the naphthalene skeleton are replaced by nitrogen From the fullerene mixture by column chromatography using₇₀Is isolated.
The isolation operation typically involves first adsorbing fullerenes to the filler and then eluting the fullerenes.
[0033]
At least C₆₀And C₇₀In order to adsorb a mixture of fullerenes containing a column filler, it is usually carried out by bringing the fullerene mixture solution into contact with the column filler, but the solvent in the fullerene mixture solution has 7 to 7 carbon atoms. 15 aromatic hydrocarbons are preferable, among which aromatic hydrocarbons having 9 or 10 carbon atoms are more preferable, and trimethylbenzene or tetralin is particularly preferable. Further, the solvent of the extract used for extracting fullerene from the soot-like substance may be used as an eluent as it is, or a part or all of the extract may be distilled off and replaced with another eluent. .
[0034]
When activated carbon is used as the column filler, among the fullerenes adsorbed on the activated carbon, C₆₀Usually, the compound species of₇₀Prior to elution of C₆₀Elute.
C₆₀As an eluent used in the case of elution, it is preferable to use a solution having a high fullerene solubility and to treat a concentrated solution as much as possible. The solubility of fullerene is 5 g / L or more, more preferably 10 g / L or more. It is particularly preferable to use a material of 15 g / L or more. Specifically, the extraction solvent used in the above-mentioned step B is used, and among them, trimethylbenzene or tetralin is preferably used.
[0035]
  C₆₀And C₇₀And a lot of efficiencyDivisionIn order to release, first, an eluent containing an aromatic compound having 10 or less carbon atoms is used.₆₀C. using an eluent containing an aromatic compound having a skeleton in which at least a part of the naphthylene skeleton or a carbon in which one or two carbons forming the naphthalene skeleton are replaced with nitrogen is eluted₇₀EluteThe
[0036]
Next, C₇₀The aromatic compound having a skeleton in which 1 or 2 of carbon forming the naphthalene skeleton or the naphthalene skeleton used as an eluent is substituted with nitrogen may have a substituent, and as the substituent, a methyl group, Examples thereof include alkyl groups such as an ethyl group, halogen atoms such as fluorine and chlorine, and halogenated alkyl groups such as a trifluoromethyl group and a chloromethyl group. However, considering the reduction of environmental burden and the convenience of handling, those having no halogen atom are preferable.
Specific examples of the aromatic hydrocarbon having a naphthalene skeleton include 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene and the like. be able to. Moreover, quinoline is mentioned as an aromatic compound which has the skeleton by which 1 or 2 of carbon which forms a naphthalene skeleton was substituted by nitrogen.
[0037]
C₇₀The eluent may be used in combination with a solvent other than the above-mentioned aromatic compound having a naphthalene skeleton, such as a mixed solvent of methylnaphthalene and trimethylbenzene, a mixed solvent of methylnaphthalene and tetralin, A mixed solvent is mentioned.
Since the eluent needs to be a liquid under the temperature and pressure conditions at the time of elution, an aromatic compound having a skeleton in which 1 or 2 of carbon forming the naphthalene skeleton or the naphthalene skeleton is replaced with nitrogen is used. Among them, when using a compound that is solid at room temperature, the temperature at the time of elution is heated to a temperature higher than the temperature at which the eluent becomes liquid.
[0038]
The temperature at the time of elution is usually 0 to 200 ° C, preferably 20 to 200 ° C, and more preferably 50 to 150 ° C. When the temperature is extremely low, elution efficiency is deteriorated, and when the temperature is extremely high, fullerenes may be decomposed.
[0039]
  The present inventionThenAs a fillerLiveCharcoalIs used.Above all, the cumulative pore volume of pores with a diameter of 2 nm or less is 0.3 cm.^Three/ G or more activated carbonPreferGood. This activated carbon is C among fullerenes.₆₀Has the smallest adsorption power to C, then C₇₀Adsorption power against C is small, C₇₀Adsorption power for higher fullerenes exceeding C is C₆₀, C₇₀Is higher than₆₀, C₇₀And C₇₀Excellent ability to separate higher-order fullerenes, resulting in high purity C₇₀Can be isolated.
[0040]
The cumulative pore volume of pores with a diameter of 2 nm or less is 0.3 cm^Three/ G or less, the adsorption capacity for fullerenes is low, and C₆₀, C₇₀And C₇₀It is difficult to separate higher-order fullerenes exceeding 1. The integrated pore volume of pores with a diameter of 2 nm or less is preferably 0.4 cm.^Three/ G or more, more preferably 0.5 cm^Three/ G or more. The upper limit is not specified, but is usually 10cm^Three/ G or less.
[0041]
The specific surface area of the activated carbon is 1600m²/ G or more, preferably 2000 m 2 / g or more, preferably 2500 m²The above is particularly preferable. When the specific surface area is in the above range, the treatment capacity of fullerenes per one time is increased.
Further, the activated carbon preferably has a ratio of particles having a particle diameter of 30 μm or less of 40% or less, preferably 30% or less, particularly preferably 25% or less. If the ratio of the activated carbon having a small particle size of 30 μm or less is within the above range, the operation of treating the mixture of fullerenes becomes easy.
[0042]
【Example】
EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
75 g of the soot-like material produced by the combustion method and 1500 mL of 1,2,4-trimethylbenzene (TMB) were mixed in a 2 L Erlenmeyer flask at room temperature 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 filter device manufactured by ADVANTEC with a diameter filter of 142 mm, PTFE, and 0.5 μm membrane filter. Of the filtrate, 118 g was concentrated up to 30 g using a Buich evaporator at 90 ° C. and 20 Torr. The liquid was put into a 500 cc separable flask and stirred with a rotary blade. After raising the temperature to 50 ° C., 125 g of THF was added with a pump over 60 minutes while maintaining the temperature. Hold for 10 minutes after addition. The solution was in a slurry state. This slurry was filtered under reduced pressure using a membrane filter having a diameter of 47 mm, PTFE, and 0.5 μm manufactured by ADVANTEC, and after completion of filtration, 50 mL of THF was further sprinkled and washed. The solid content separated by filtration was dried under conditions of 100 ° C. and 5 Torr or less using a vacuum dryer. The fullerenes thus obtained had a fullerene purity of 91.9% by weight and contained 289 ppm by weight of a polycyclic aromatic compound.
The fullerenes were analyzed using liquid chromatography, and the polycyclic aromatic hydrocarbons were analyzed using gas chromatography.
[0043]
(Creation of activated carbon column)
Powdered activated carbon MAXSORB MSC30 manufactured by Kansai Thermochemical Co., Ltd. (integrated pore volume of pores having a diameter of 20 mm or less; 0.55 cm^Three/ G, specific surface area 3,250 square meters / g; potassium hydroxide activated). 95.1g is weighed on top of 286, and sieved in the air at a strength of scale 50 for 5 minutes using a sieve shaker VSS-50 manufactured by Tsutsui Rika Kikai Co., Ltd. and a sieve with an opening of 26 micrometers. , 49.5 g remained on the sieve and was transferred to a 1 L glass beaker. While changing the amount weighed on the sieve, the same operation was further repeated twice to obtain a total of 177.6 g of MAXSORB MSC30 remaining on the sieve. 0.2 mg of MAXSORB MSC30, which is a commercial product, and MAXSORB MSC30 remaining on the sieve were 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. Of the sieve residue, the ratio of particles having a particle size of 30 μm or less was 13%.
[0044]
  When the specific surface area of MAXSORB MSC30 which is a commercial product and MAXSORB MSC30 remaining on the sieve was calculated by the BET multipoint method in the range of relative pressure of 0.002 to 0.2, each was 2994 m.²/ G, 2990m²/ G. When the pore volume was calculated from the amount of nitrogen adsorbed at a relative pressure of 0.93, the commercially available product was 1.60 cm.^Three/ G, sieve residue is 1.59 cm^Three/ G. 130 g of the sieve residue is transferred to another 1 L beaker, and heat is removed in a 22 ° C. water bath while being manufactured by Maruzen Petrochemical Co., Ltd. 1, 2, 4−An activated carbon slurry was prepared by slowly adding 0.6 L of trimethylbenzene (also known as pseudocumene) over 5 minutes while stirring.
[0045]
An eye plate was placed at the bottom of a column made of SUS304 (column inner diameter 8 mm, height 100 mm), and Advantech filter paper 5C cut out to a diameter of 8 mm was placed on the plate, and attached to the column body and fixed. The upper part of the column was removed, and 4 mL of the activated carbon slurry was poured into the column body and sucked under reduced pressure from the bottom outlet, and an activated carbon bed was created while extracting trimethylbenzene from the slurry. Trig methylbenzene is extracted until just before the upper part of the activated carbon bed is above the liquid level, and an activated carbon bed with a layer height of 98 mm is created while repeating the operation of adding slurry, and the upper flange with the eye plate and filter paper is attached. Fixed with screws. The volume of the activated carbon bed is 5cm^ThreeMet. The column was attached to the liquid feeding line.
[0046]
(Creation of raw material liquid)
Fullerene (C60; 61%, C70; 24%, including a small amount of polycyclic aromatic hydrocarbons; 35.02 g) obtained by the above combustion method is weighed into a 6 L SUS raw material tank, and 6 L of trimethylbenzene is charged. Then, a three-one motor with a stirring blade was attached and stirred well for 1 hour at a strength of 5 to obtain a raw material solution. A trimethylbenzene 6L raw material tank was attached to the liquid feed line. Subsequently, 5 L of trimethylbenzene was charged into the eluent tank and attached to the liquid feed line.
[0047]
(Liquid feed)
After the upper part of the column and the liquid feed line were temporarily separated, the pump was driven to remove the air in the liquid feed line while feeding the raw material liquid. Immediately after the pump was stopped, the upper part of the column was connected to the liquid feed line.
A screw bottle with a capacity of 110 mL was installed at the outlet at the bottom of the column so that the effluent could be collected, and when the pump was driven to start feeding the raw material liquid, a colorless and transparent liquid flowed out of the outlet. When the outflow rate was 3 mL / min, the pressure gauge display was 0.2 MPa. When 77 mL of the raw material liquid was poured as it was, it was switched to the next screw bottle.
[0048]
(C₆₀Eluent delivery)
When the feeding of 77 mL of the raw material liquid was completed, the pump was stopped, the valve was switched, and the feeding of trimethylbenzene as the eluent was started. 33 minutes after starting the feed of the raw material liquid, it was confirmed that the C60 component started to flow out and the liquid color was purple when about 100 mL flowed out.
Here, 77 mL of the raw material liquid was 15.4 times the volume VB of the activated carbon bed. The ratio of the total amount V of the raw material liquid and the eluent to the volume VB of the activated carbon bed, that is, V / VB may be handled as an index of the effluent amount.
The second and subsequent fractions were collected while changing the fraction every time the effluent amount reached 100 mL, a total of 396 mL of trimethylbenzene was fed, and the pump was stopped when the collection of the fifth fraction was completed.
[0049]
(C₇₀Eluent delivery)
600 mL of 1-methylnaphthalene manufactured by Tokyo Chemical Industry was put into a 1000 mL glass beaker and attached to the liquid feeding line of the pump. The pump liquid feed line had an outer diameter of 3 mm, an inner diameter of 1 mm, and a length of 1 m, and was bent in the vicinity of where the column was mounted so that most of the line was in the vicinity of the column. The pump was driven after temporarily detaching the connection between the column upper part and the liquid feeding line, and while replacing 1-methylnaphthalene, the liquid feeding line was replaced and the remaining air in the piping was removed. Immediately after the pump was stopped, the upper part of the column was connected to the liquid feed line. The entire column and most of the liquid feed line were attached to a circulating oil bath, and the temperature of the oil bath was set to 120 ° C. One hour later, when the temperature of the oil bath reached 120 ° C., the feeding of 1-methylnaphthalene was started. 25 mL was fractionated as 6 to 9 fractions, and then 100 mL was fractionated as 10 to 14 fractions, and the pump was stopped when a total of 594 mL of 1-methylnaphthalene was fed.
[0050]
(Analysis and results)
From the results of LC analysis of each fraction, the concentrations of C60 oxide, C60, C70 and further fullerene having a higher molecular weight were calculated to obtain a chromatogram. Fullerenes having a molecular weight higher than that of C70 did not flow out. The chromatogram of each component is shown in FIG. Further, the C60 recovery rate calculated from the weight ratio of C60 contained in 77 mL of the raw material solution to the total weight of C60 contained in fractions 1 to 5 was 70.0%. Further, the sum of C60, C70 and other components contained in fractions 1 to 5 was obtained, and the purity of C60 when fractions 1 to 5 were the same was calculated to be 99.2%. The recovery rate of C70 was calculated from the weight ratio of C70 contained in 77 mL of the raw material solution to the total weight of C70 contained in fractions 10 to 14, and found to be 54.3%. Further, the sum of C60, C70 and other components contained in fractions 10 to 14 was obtained, and the purity of C70 when fractions 10 to 14 were the same was calculated to be 97.3%.
[0051]
(Example 2)
Isolation of fullerene obtained by the combustion method in the same manner as in Example 1 except that 1,2,4 trimethylbenzene and 1-methylnaphthalene used in Example 1 were purified by multistage distillation. When purification was attempted, almost the same result as in Example 1 was obtained. It was confirmed that the solvent can be recycled.
[0052]
(Comparative Example 1)
C₇₀Attempts were made to isolate and purify fullerene obtained by the combustion method in the same manner as in Example 1 except that o-dichlorobenzene was used as the eluent for use and the temperature at that time was 20 ° C. C₇₀There is almost no elution of C₇₀The recovery rate was less than 10%.
(Comparative Example 2)
C₇₀Attempts were made to isolate and purify fullerene obtained by the combustion method in the same manner as in Example 1 except that toluene was used as the eluent for use and the temperature at that time was 20 ° C.₇₀There is almost no elution of C₇₀The recovery rate was less than 5%.
[0053]
【The invention's effect】
According to the present invention, C₇₀Can be provided in a large amount and with high purity.

Claims (5)

A mixture of fullerenes containing at least C ₆₀ and C ₇₀ is adsorbed on activated carbon, and at least a part of C ₆₀ is eluted from the activated carbon using an eluent containing an aromatic hydrocarbon compound having 10 or less carbon atoms, and then naphthalene. methods of isolating C _70, characterized in that eluting of C ₇₀ with an eluent containing an aromatic compound having a skeleton 1 or 2 is replaced by nitrogen atoms which form the skeleton or naphthalene skeleton. Aromatic compounds having a naphthalene skeleton or a skeleton in which one or two carbon atoms forming the naphthalene skeleton are replaced by nitrogen are 1-methylnaphthalene, 2-methylnaphthalene, 1,2-dimethylnaphthalene, 1,4-dimethylnaphthalene method for isolating C ₇₀ according to claim 1, wherein the 1,5-dimethylnaphthalene or quinoline. Claim 1 or 2 1 or 2 carbon that forms a naphthalene skeleton or a naphthalene skeleton temperature of the eluting solution containing the aromatic compound having an alternative backbone nitrogen is characterized in that it is a 20 to 200 ° C. isolation method of C _70. An aromatic hydrocarbon solution of a mixture of fullerenes containing at least C ₆₀ and C ₇₀ and activated carbon are brought into contact with each other to adsorb the mixture of fullerenes containing at least C ₆₀ and C ₇₀ on the activated carbon. methods of isolating C ₇₀ according to any one of 1 to 3. When adsorbing a mixture of fullerenes to the activated carbon comprising at least C ₆₀ and C _70, as claimed in claim 1, wherein contacting the activated carbon and the mixture as an aromatic hydrocarbon solution of 7 to 15 carbon atoms methods of isolating C ₇₀ of any one.