JPH09249406A - Extraction of fullerenes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for extracting fluoresces from a fullerene- containing raw material with a column chromatograph, capable of simply extracting the carious fullerenes different in carbon number by preliminarily applying an impact treatment using polar solvent molecules to the fullerene- containing raw material. SOLUTION: When fullerenes are extracted from a fullerene-containing raw material with a column chromatograph, an impact treatment using polar solvent molecules is preliminarily applied to the fullerene-containing raw material. When the polar solvent is the supercritical solution of water and/or carbon dioxide, the efficiency of the fullerene extraction can further by improved. The execution of the impact treatment under a high pressure gives an effect enabling the further selective extraction of the various fullerenes. The simultaneous employment of a proper extraction solvent and a physical operation such as an ultrasonic wave application or a high speed agitation operation enables to further improve the efficiency of the fullerence extraction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an extraction method capable of easily obtaining fullerenes having various carbon numbers from fullerene-containing raw materials.

[0002]

BACKGROUND OF THE INVENTION Fullerenes are unique carbon clusters which are obtained from abundant carbon resources as a raw material and have a basic structure of a super ring structure having a space in the center. In addition to the basic structure, the carbon clusters are also diverse in terms of shape and structure, such as those in which a metal is included in the central space and multimers of the basic structure.

In recent years, attractive physical properties derived from such structural peculiarities have attracted attention, and application to the electronics industry as isotropic conductors and superconductors, utilization as molecular magnetic substances, physiological activity. In many industrial fields, research is being conducted on the practical feasibility of unknown new materials such as application to materials and use as new functional materials by chemical modification.

By the way, in the case of a fullerene-containing raw material, such as soot, according to mass spectrum analysis, fullerenes have sufficient carbon atoms such that C60, C62, C64 ... It has been clarified that it produces in a ratio. The fact that the physical properties of fullerenes change significantly as the number of carbons increases is sufficiently expected from the example of hydrocarbons, and from the specificity of the fullerene structure, fullerenes with different carbon numbers are The properties of are all expected to be different. Therefore, it is considered that among these fullerenes, there are also fullerenes having physical properties that can be excellent new materials, and research on the physical properties of fullerenes having different carbon numbers is underway.

However, the fullerenes whose physical properties have been relatively researched so far are limited to the fullerenes which can be efficiently extracted using a certain organic solvent. Specifically, C60 and C70 are the main ones, which allow extraction of macroscopic quantities, that is, quantities sufficient for conducting experimental research.
Other fullerenes, such as higher fullerenes, oxides of fullerenes, multimers of fullerenes, and metal-encapsulated fullerenes, have not yet been satisfactorily undertaken even in basic experimental research, and are within the range of theoretical theoretical research. Is in a situation that has not left. The reason for this is that the ability to extract fullerenes with organic solvents is limited, and fullerenes mainly having carbon numbers other than C60 and C70 cannot be easily obtained in an amount necessary for experimental research.

Speaking of higher-order fullerenes, higher-order fullerenes of C90 or higher are present in large amounts in soot produced by arc discharge of graphite in helium gas, for example, and the total amount thereof is higher than that of C60. Despite being much more numerous, it is rarely extracted from soot. Specifically, it is necessary for at least one month to secure a sufficient amount of C76 to C84 fullerenes whose physical properties can be measured, and the same amount of C84 fullerenes can be used with a certain extraction solvent. If it were to be obtained, it would take several months for its extraction and isolation. Furthermore, extraction and isolation of fullerenes of C90 or higher requires unpredictable time and labor.

[0007]

Therefore, conventionally, in order to enhance the extraction ability of fullerenes by an extraction solvent such as an organic solvent, it is necessary to increase the solubility of fullerenes in the extraction solvent. Attempts to extract fullerenes at high temperatures by studying solvents such as carbon disulfide, which has a high extraction capacity, and by using high boiling point solvents, 1,2,4 trichlorobenzene and 1,2,3,5 tetramethylbenzene. It has been made. However, the methods using these extraction solvents have problems that impurities are mixed in the extract and that it takes time to concentrate the extraction solution. In addition to the extraction method using such a solvent, a method for separating and purifying fullerenes from soot utilizing the difference in sublimation temperature of various fullerenes is also proposed, but it is also applied to fullerenes with high sublimation temperatures. It is difficult and is not suitable for processing a large amount of soot.

Although attempts have been made to efficiently extract fullerenes in this way, some of the soot after extraction is
Mass spectrometric analysis has revealed that many fullerenes are present in high concentrations. Furthermore, as a method for increasing the solubility of fullerenes in organic solvents, attempts have been made to extract fullerenes by treating a solution of soot in xylene or toluene under high temperature and high pressure using an autoclave. However, under high temperature and high pressure, the organic solvent is decomposed and polymerized to generate various by-products, so that there is a problem that high-purity fullerenes cannot be obtained.

Therefore, of the present invention, the invention according to claim 1 makes it possible to easily extract various fullerenes having different carbon numbers, thereby contributing to experimental research for elucidating the physical properties of fullerenes and The purpose is to give a guide to the technological development for mass production of the products. In addition to the object of the invention described in claim 1, it is an object of the invention described in claim 2 to provide a method for extracting fullerenes capable of further improving the extraction efficiency. further,
In addition to the object of the invention according to claim 1 or claim 2, the invention according to claim 3 aims to provide an extraction method which enables selective extraction of various fullerenes.

[0010]

In order to achieve the above object, the invention according to claim 1 of the present invention is characterized in that when a fullerene is extracted from a fullerene-containing raw material by column chromatography, the fullerene-containing raw material is preliminarily polarized. It is characterized in that it is subjected to impact treatment with solvent molecules. Thus, by preliminarily subjecting the fullerene-containing raw material to a microscopic molecular impact to weaken the bond between the raw material and the fullerene, various fullerenes having different carbon numbers can be obtained in the subsequent general extraction operation. It can be easily extracted.

The invention of claim 2 is characterized in that, in the constitution of the invention of claim 1, the polar solvent is a supercritical solution of water and / or carbon dioxide. With such an extraction method, in addition to the effect of the invention described in claim 1, the extraction efficiency can be further improved.

The invention according to claim 3 is characterized in that, in the constitution of the invention according to claim 1 or claim 2, the impact treatment is performed under a high pressure. By adding the condition of high pressure, in addition to the effect of the invention described in claim 1 or 2, it becomes possible to selectively extract various fullerenes.

Soot is a typical example of the above-mentioned "fullerene-containing raw material", and this soot can be obtained by heating graphite by laser radiation or arc discharge, or by burning organic matter. For example, the soot produced by arc-discharging a graphite electrode in helium gas contains about 30% of fullerenes. Here, except for the fullerenes, amorphous carbon is used. However, since the fullerenes are incorporated into the network, the present inventors have previously pulverized the network or used a molecular mutual agent. We thought that if the action could be weakened in strength, various fullerenes could be easily extracted even with the use of conventional solvents, and therefore earnest experiments were conducted to find such a microscopic crushing means.

At this time, the present inventors have found that the physical properties of fullerenes differ with the number of carbons, so that the interaction between amorphous carbon and various fullerenes in soot also differs, and if the number of carbons increases. It is expected that the interaction will become stronger as the number increases, so using water under atmospheric pressure and under high temperature and high pressure (including supercritical state) using an autoclave,
Therefore, an attempt was made to impact the soot with water molecules (hereinafter, this treatment is referred to as "hydrothermal shock treatment") to weaken the bond between the soot and fullerene. High-performance liquid chromatography for collecting soot after hydrothermal shock treatment (High Performance L
iquid Chromatography, hereinafter abbreviated as "HPLC". ), It can be confirmed that various fullerenes can be efficiently and selectively extracted, and is unique to the present invention whose main point is "to subject the fullerene-containing raw material to impact treatment with polar solvent molecules in advance". It has reached a method for extracting fullerenes.

The reason why polar solvent molecules are used here is that non-polar solvent molecules do not improve the extraction efficiency even if subjected to impact treatment. In addition, as the polar solvent, it is possible to use other than water, but in the case of water, since the fullerene is not dissolved and unnecessary reaction products are not generated, all the thermal energy of water molecules There is an advantage that can be given to soot, which is preferable. It is also economical. However, it is also possible to increase the extraction efficiency of fullerenes by using a supercritical solution of carbon dioxide as a polar solvent or by using it in combination.

Further, it was confirmed that the higher the polarity of the soot treatment solvent after the hydrothermal shock treatment, the easier the fullerenes are extracted. It is also possible to further improve the extraction efficiency of fullerenes by a physical operation such as ultrasonic wave or high-speed stirring, or by using an appropriate extraction solvent together.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification or modification made within the scope not departing from the gist of the preceding and the following will be technical technical aspects of the present invention. Included in the range.

[0018]

EXAMPLES Soot containing fullerenes was produced by direct current arc discharge using a graphite rod of φ6 mm × 150 mm in a helium gas atmosphere. In this case, the pressure of the helium gas was set to 100 Torr and the discharge current was set to 100A. All the soot that was generated and adhered in the chamber was collected, uniformly mixed, and then subjected to the test. The collected soot was measured by laser ionization mass spectrometry in advance.
The result shown in FIG. As is clear from FIG. 1, C
It is well understood that fullerenes are formed in a sufficient abundance ratio up to C150 (everything after C124 is omitted in Fig. 1) at every two carbons, including 60.

Comparative Example 1 First, a test was conducted to grasp beforehand the extraction efficiency when the soot collected as described above was simply extracted with an organic solvent as in the conventional representative example. That is, 50 mg of soot was Soxhlet-extracted with 100 ml of toluene, and measured by laser ionization mass spectrometry. FIG. 2 shows the result of this measurement. As is clear from this figure, in the conventional method of simply extracting with toluene, the types of fullerenes that can be extracted are only C60, C70, C76, C78, C82, C84, and other fullerenes are hardly extracted. I understand. Further, the results of measuring the fullerenes remaining in the soot after extraction with toluene by laser ionization mass spectrometry are shown in FIG.
It can be seen that fullerenes, especially higher-order fullerenes of C90 or higher, remain almost unextracted.

(Example 1) 50 mg of soot collected as described above was put into 15 cc of water, and dispersion treatment was carried out for 10 minutes by utilizing the stirring action by ultrasonic waves. Then, the dispersion solution was 373 K in a flask. After refluxing for 24 hours at 333 K, it was dried at 333 K for 12 hours. 10 samples after drying
When the extract obtained by Soxhlet extraction with 0 ml of toluene was measured by laser ionization mass spectrometry, the results shown in FIG. 4 were obtained. Next, the results of the same analytical measurement of fullerenes remaining in the soot after extraction are shown in FIG. It was confirmed in FIG. 4 that many high-order fullerenes with a mass number of up to about 1600 were extracted, and in FIG. 5, the amount of higher-order fullerenes decreased to a negligible level, that is, It is shown that almost no residue remains, and it was confirmed that the fullerene extraction method according to the present invention is very effective in terms of extraction efficiency.

(Example 2) A toluene extracted sample of the above Example 1 was converted into a monomeric octadecylsilica coloum (0DS).
A column) was used to move in a mobile phase consisting of toluene and methanol (however, a toluene: methanol ratio of 49:51) at a rate of 0.7 ml / min, and measurement was carried out by HPLC. The sample subjected to the hydrothermal shock treatment of Example 1 and extracted with toluene was sample A. For comparison, the sample extracted with toluene without the hydrothermal shock treatment of Comparative Example 1 was simply sample B. Carbon disulfide (CS ₂ )
Extract the sample C and trichlorobenzene (TCB)
The extract was used as sample D, and HPLC was performed for each.
FIG. 6 shows a comparison of the values measured in 1. As is clear from FIG. 6, in the sample A obtained by the fullerene extraction method of the present invention, the sample B obtained by the conventional method,
New and prominent peaks Xa, Xb, Xc, Xd, e and Xf of the fullerenes, which cannot be found in C and D, were observed. It can be well understood that the present invention is very effective as a method.

Example 3 For the purpose of isolating higher-order fullerenes of C90 or higher from the soot of the sample used in Example 1, the absorbance peaks were measured by liquid chromatography with a column manufactured by Waters Co. Xa, X. -B, X-c, X-
Isolate the components of what is d, e, Xf (see FIG. 6),
Each of the results was measured by laser ionization mass spectrometry and also by HPLC, and the respective results are shown in FIG.
It shows in (a) and FIG.7 (b). X-b is considered to be a C60 dimer or C60-0-C60, and X-c is C90, X-d,
e is considered to be a dimer, trimer, etc. containing C92, C94, C96 and / or C70. Further, in X-f, higher fullerenes up to C180 and its oxide were observed. (Example 4) In the same manner as in Example 1, soot 50 mg was added to 15 cc
Of water and disperse for 10 minutes using ultrasonic waves, and then put the dispersion solution in an autoclave,
Hydrothermal shock treatment was carried out at 534 ° K for 24 hours. The treated solution was then filtered and dried at 333 K for 12 hours. The dried sample was measured by HPLC in the same manner as in Example 2. The results are shown in comparison with FIG. 8 for comparison with Example 2. From FIG. 8, in the soot-containing dispersion liquid subjected to the hydrothermal shock treatment under high pressure, the extraction amounts of C76, C78, C80 and higher fullerenes are reduced as compared with those under the normal pressure treatment. However, the amount of C84 extracted is conversely 2.
You can see that it has increased five times. That is, as shown in FIG. 8, it was confirmed that various fullerenes can be selectively extracted by changing the energy of water molecules during the hydrothermal shock treatment.

[0023]

As described above, in the method for extracting fullerenes according to claim 1 of the present invention, the fullerene-containing raw material is preliminarily subjected to impact treatment with a polar solvent molecule, and the fullerene in the raw material is subjected to impact treatment. Since the binding strength of the compounds was markedly reduced microscopically and then extracted with an appropriate solvent, various fullerenes having different carbon numbers including C90 or higher can be easily extracted. Became. Further, the extraction method of the present invention is not limited to extraction of higher fullerenes (including oxides and multimers), but also as a separation technique for metal-encapsulated fullerenes, and further carbon nanotubes, particularly single fiber nanotubes, from a fullerene-containing raw material. It can be effectively applied. As a result, the method of the present invention is useful for experimental research for elucidating the physical properties of fullerenes, and also provides useful guidelines for mass production of fullerenes.

The invention according to claim 2 is the structure of the invention according to claim 1, wherein the polar solvent is a supercritical solution of water and / or carbon dioxide. In addition to the effect of the invention described above, the extraction efficiency can be further improved.

According to a third aspect of the present invention, in the constitution of the first or second aspect of the present invention, the impact treatment is performed under a high pressure. In addition to the effect of the invention described in Item 2, various fullerenes can be selectively extracted.

[Brief description of drawings]

FIG. 1 is a diagram showing measurement results of laser ionization mass spectrometry of soot generated by arc discharge.

FIG. 2 is a diagram showing a measurement result of laser ionization mass spectrometry of a soot produced by arc discharge which was simply extracted with toluene.

FIG. 3 is a diagram showing the measurement results of laser ionization mass spectrometry of the remaining soot generated by arc discharge after extraction with toluene.

FIG. 4 is a diagram showing a measurement result of laser ionization mass spectrometry of a soot subjected to hydrothermal shock treatment and extracted with toluene.

FIG. 5 is a diagram showing the measurement results of laser ionization mass spectrometry of the rest of soot subjected to hydrothermal shock treatment after extraction with toluene.

FIG. 6 shows that the soot subjected to the hydrothermal shock treatment is extracted with toluene, and the soot is extracted directly with a solvent.
It is a figure which shows and compares the result measured by HPLC.

7 is a diagram showing the results of isolating and analyzing the components of each absorbance peak in sample A of FIG. 6, in which FIG. 7 (a) shows the measurement results of laser ionization mass spectrometry, FIG. (b) is a figure which shows the result measured by HPLC.

FIG. 8 is a diagram showing a comparison of the results of measurement by HPLC for each of the soot subjected to hydrothermal shock treatment under high pressure with toluene and the soot subjected to hydrothermal shock treatment under normal pressure with toluene. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Barachandran Jeyadewan 2-2-28 Mikamimine, Taihaku-ku, Sendai-shi, Miyagi Golden Heights Iwatani E-111 (72) Inventor Eiji Takahashi Kurio, Aoba-ku, Sendai-shi, Miyagi Prefecture −7-10 Turtle House 201 (72) Inventor Takashi Goto 2-6-30 Hachiman, Aoba-ku, Sendai-shi, Miyagi AP203 (72) Inventor Yukitoshi Akiyama 2-12-8 Takamatsu, Aoba-ku, Sendai-shi, Miyagi 103 Arihoso 103 (72) Inventor Shigeyuki Ukita 2181-2 Nakahime, Onohara, Mitoyo-gun, Kagawa Toyo Carbon Co., Ltd., Onohara Technology Development Center (72) Inventor Toshiaki Sokabe 2181-2, Nakahime, Onohara, Mito-gun, Kagawa Prefecture Toyo Tanso Co., Ltd. (72) Inventor Ken Nagasawa, Onohara Technology Development Center Co., Ltd. 2181-2 Nakahime, Onohara, Mitoyo-gun, Kagawa Toyo Carbon Co., Ltd. Onohara technology development in the center (72) inventor Tetsuro Tojo Kagawa Prefecture Mitoyo-gun Onohara Oaza Chuhime 2181-2 Toyo carbon Co., Ltd. Onohara Technology Development Center in

Claims (3)

[Claims] 1. A method for extracting fullerenes, which comprises subjecting the fullerene-containing raw material to impact treatment with a polar solvent molecule in advance when extracting the fullerene from the fullerene-containing raw material by column chromatography. 2. The method for extracting fullerenes according to claim 1, wherein the polar solvent is a supercritical solution of water and / or carbon dioxide. 3. The method for extracting fullerenes according to claim 1 or 2, wherein the impact treatment is performed under high pressure.