JPH06118074A - Separating method for fullerenes - Google Patents

Abstract

PURPOSE:To satisfactorily separate fullerences by using a silica gel powder sintered at a specified temperature or more as a filler, and chromatographing the furalenes. CONSTITUTION:As silica gel particles, spherical and crushed ones having average particle sizes of about 3-500mum which are obtained from neutralizing reaction of alkali silicate are used, and the particles obtained by baking them at about 600 deg.C or more are used as a filler. An excessively low baking temperature can not provide the filler capable of satisfactorily separating furalenes, and an excessively high temperature makes the silica gel half-melted state, resulting in an unpreferable reduction in specific surface area and pore capacity. The baking time is differed depending on the temperature, but generally set to about 1-10 hours. Otherwise, those obtained by supporting a proper metal oxide by the silica gel particles can be used, and when alumina is supported, particularly, separating performance of fullerences is more improved. The thus-baked silica gel particles are used as the filler to perform chromatography. Fullerences, particularly, a mixture of C60 and C70, can be efficiently separated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating fullerenes, and more particularly to a method for efficiently chromatographically separating fullerenes such as C ₆₀ and C ₇₀ .

[0002]

2. Description of the Related Art Currently, C _60- based fullerenes are being manufactured and applied to various fields. Fullerenes are produced by extracting soot generated by arc discharge of a carbon electrode with an organic solvent or the like,
This extract is a mixture of C _70, which is mainly C ₆₀ , and higher molecular weight, and needs to be manufactured separately. Although many methods have been tried for this separation method, a chromatographic separation method using a packing material is performed as one of them. Fullerene does not have a specific functional group in its structure, and its polarity as a molecule was small and it was difficult to separate it with general adsorbents. However, it was recently separated with alumina and octadecylsilylated silica gel. It has been found that the above can be carried out, and trial separation and purification are started. However, alumina fillers have high performance as commercial products, for example, few are available as fillers for high performance liquid chromatography, and octadecylsilylation-treated silica gel is an expensive filler, which is costly for industrialization. There's a problem. As a result of extensive studies to solve such problems, it was found that the silica gel can easily exhibit a specific adsorption power for fullerenes by treating silica gel for chromatography at high temperature.

[0003]

In view of the above-mentioned circumstances, the present invention is to provide a method capable of favorably separating fullerenes such as C ₆₀ and C ₇₀ .

[0004]

Means for Solving the Problems As a result of various studies conducted by the present inventors in order to achieve the above object, when silica gel after firing at a certain temperature or higher is used as a filler, fullerenes are obtained. It was found that the chromatographic separation of can be carried out specifically.

That is, the gist of the present invention resides in a method for separating fullerenes, which is characterized in that silica gel particles after firing fullerenes at a temperature of 600 ° C. or higher are used as a packing material for chromatographic separation. Hereinafter, the configuration of the present invention will be described in detail.

The silica gel particles used in the present invention are usually spherical and crushed silica gel having an average particle size of 3 to 500 μm obtained by a neutralization reaction of alkali silicate. The physical properties of the silica gel particles are, for example, 0.2 to 2.0 ml / g in pore volume and 10 to 80 in specific surface area.
It is preferably 0 m ² / g and has an average pore diameter of 10,000 angstroms or less.

In the present invention, such silica gel particles have a temperature of 600 ° C. or higher, preferably 700 ° C. or higher, particularly 800 to
It is an essential requirement to use silica gel particles fired at 1000 ° C. as a filler. When the firing temperature is low, it is not possible to obtain a filler capable of separating the fullerenes satisfactorily. On the contrary, when the firing temperature is too high, the silica gel becomes in a semi-molten state, and the specific surface area and the pore volume decrease. Absent. The firing time varies depending on the firing temperature, but is usually about 1 to 10 hours.

Further, in the present invention, it is also possible to use silica gel in which an appropriate metal oxide is supported when firing the silica gel particles. As the metal oxide to be supported, various ones can be mentioned, and in particular, when alumina is supported, the separation ability between C ₆₀ and C ₇₀ is further improved, which is preferable. As a method of supporting alumina on the silica gel particles, for example, the silica gel particles are immersed in an aqueous solution of an aluminum salt such as aluminum chloride, the pH is adjusted to about 3 to 5 with an alkali, and then this is separated, and if necessary, separated. It can be performed by washing with water, methanol and drying. The amount of alumina supported on the silica gel particles is usually about 50 to 50,000 ppm.

In the present invention, fullerene is chromatographically separated using silica gel particles that have been subjected to the above-mentioned calcination as a filler. The method and conditions for the chromatographic separation can be carried out by known methods. . In short, fullerenes can be separated by a known high-performance liquid chromatography equipped with a column packed with the packing material of the present invention, employing a conventional processing method. Particularly in the case of the present invention, as is apparent from the examples described later, it is an excellent method for separating each C ₆₀ / C ₇₀ mixture.

[0010]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist. Examples 1-2 and Comparative Examples 1-3 Commercially available silica gel particles for HPLC shown in Table 1 (super microbeads, 100 Å, 10 μm)
Was placed in an alumina crucible and baked in an electric furnace at the temperatures shown in Table 2 for 2 hours each to prepare the packing material for chromatography of the present invention.

[0011]

[Table 1]

[0012]

[Table 2]

Each spherical silica gel obtained by the above-mentioned preparation method was used as a packing material, and this was packed in a column by the slurry packing method to obtain C ₆₀ /
The C ₇₀ mixture was used as a sample and the normal phase high performance liquid chromatographic separation characteristics were tested under the following conditions.

Column = 4.6 μ × 250 mm (stainless steel) Mobile phase = n-hexane Flow rate = 1 ml / min (pump = Yonaco L-40
00W) Detection = UV350mm (Detector Shodex M-31
5) The results of these tests are as shown in each peak in the attached drawings.
In the case of Examples 1 and 2, the peaks shown in FIGS.
As it is clear from C₆₀And C₇₀Is efficiently separated from
However, in the case of Comparative Examples 1 to 3, the peaks in FIGS.
As you can see C ₆₀And C₇₀And the peaks overlap and the separation is good.
I couldn't do it. Example 3 In Example 1, 10 g of silica gel particles as a raw material was added to 0.1
Aluminum chloride (AlCl₃ ・ 6H
₂ O) soak in a solution of 1.18 g for 30 minutes
After stirring, add diluted ammonia water to adjust the solution to pH 4.
After that, after stirring for another 30 minutes, this was passed through a suction furnace, and then
Washed sequentially with 200 ml of deionized water and 200 ml of methanol
Clean After drying this silica gel at 170 ° C., 95
Alumina is supported by firing for 2 hours at a temperature of 0 ° C.
Preparation of silica gel with a holding capacity of 1% (measurement by atomic absorption method)
did.

[0015] was subjected to a test of chromatographic separation characteristics of the C ₆₀ / C ₇₀ mixture at the same conditions as in Example 1 by using this alumina-supported silica gel, C ₆₀ and C ₇₀ As is clear from the peak a in FIG. 6 Was effectively separated.

[0016]

According to the present invention, C ₆₀ and C ₇₀ fullerenes can be efficiently separated. Although the cause of this is not clear, it is considered that only the isolated silanol group remains on the surface of the silica gel due to the high temperature firing, and the isolated silanol group exhibits specific adsorptivity for fullerenes. Furthermore, when other metal oxides such as alumina are added to the silica gel, the specific adsorption effect is further enhanced.

As described above, according to the present invention, C ₆₀ and C ₇₀ can be efficiently separated, so that it can be said that the present invention has a great utility value for widespread practical use of fullerenes in the future.

[Brief description of drawings]

1 shows separation peaks in a normal phase high performance liquid chromatographic separation characteristic test of Example 1. FIG.

FIG. 2 shows separation peaks in a normal phase high performance liquid chromatography separation characteristic test of Example 2.

FIG. 3 shows separation peaks in a normal phase high performance liquid chromatography separation characteristic test of Comparative Example 1.

FIG. 4 shows separation peaks in a normal phase high performance liquid chromatographic separation characteristic test of Comparative Example 2.

5 shows separation peaks in a normal phase high performance liquid chromatographic separation characteristic test of Comparative Example 3. FIG.

FIG. 6 shows separation peaks in a normal phase high performance liquid chromatography separation characteristic test of Example 3.

Claims (2)

[Claims] 1. A method for separating fullerenes, which comprises performing a chromatographic separation using silica gel particles after firing the fullerenes at a temperature of 600 ° C. or higher as a filler. 2. The method for separating fullerenes according to claim 1, wherein silica gel particles carry alumina.