JPH06166509A - Production of heteroatom-containing fullerene - Google Patents

Abstract

PURPOSE:To provide a method for producing heteroatom-contg. fullerenes continuously in large quantities. CONSTITUTION:The objective fullerenes can be obtained by introducing (A) simple substance(s) of at least one kind of element selected from metallic elements, boron, nitrogen, phosphorus and silicon, or (B) compound(s) of such element(s) and (C) a carbonaceous material into a hot plasma zone to effect evaporative decomposition followed by deposition again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heteroatom-containing fullerene. Heteroatom-containing fullerenes are expected to be applied to high lubricants, high hardness materials, catalyst carriers, semiconductor materials and the like.

[0002]

BACKGROUND OF THE INVENTION Heteroatom-containing fullerenes are known as "The Jour.
nal of Physical Chemistry ”1991 Volume 95 756
Its presence was reported on page 4. According to reports, metal oxide and graphite powder are kneaded and mixed at a pitch, and after molding, arc discharge is performed using an electrode that is calcined and carbonized at a temperature of about 1200 ° C., and metal is contained in the soot generated from the generated steam. The contained fullerenes are produced, and are separated by crystallizing and producing from a liquid extracted with toluene or the like like fullerenes. See also Material
ls science Proceedings 19
In 1991, 206, p. 627, the production of metal-containing fullerenes was confirmed by mass spectrum also in the laser evaporation method using a target obtained by kneading a metal oxide with graphite powder using the same pitch and firing and carbonizing the same.

These methods produce extremely small amounts of metal-containing fullerenes. As the metal, Y,
La, Sc, K, Cs, etc. are selected and their oxides or salts are used. It is said that these metals are contained in fullerenes, especially C ₈₂ , and it is also reported that they are stable in the air and are stable. It has been reported that C ₆₀ and C ₇₀ other than these are also contained in a small amount. Whether or not these metals are contained in the closed shell structure remains controversial, but there is no doubt that they are extremely stable even if they are outside.

[0004]

However, in the above method, the amount produced is extremely small. Further, these are batch methods and are not suitable for industrial production. Therefore, in the present situation, even the measurement of physical properties is not clear, and in order to use metal-containing fullerenes as functional thin films, reaction intermediates, etc., a large-scale and inexpensive manufacturing method is required.

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, simple substances of one or more elements selected from the group consisting of metallic elements, boron, nitrogen, phosphorus and silicon, or compounds and carbonaceous materials thereof. The present inventors have found that it is possible to continuously and in large quantities produce heteroatom-containing fullerenes by introducing a raw material into a thermal plasma zone, evaporating and decomposing it, and then reprecipitating it.

That is, an object of the present invention is to provide heteroatom-containing fullerenes industrially advantageously.

[0007]

The object of the present invention, however, is to heat a simple substance of one or more elements selected from the group consisting of metallic elements, boron, nitrogen, phosphorus and silicon, or a compound thereof, and a carbonaceous raw material. It can be easily achieved by introducing into the plasma zone, evaporative decomposition, and then re-deposition.

The present invention will be described in more detail below. The carbonaceous raw material used in the present invention is not particularly limited as long as it is a substance mainly composed of carbon, and depending on the case, hydrogen or oxygen may contain an element other than carbon, but the carbon content is high. Substances are preferably used. Specific examples thereof include carbon black, graphite powder, carbon fiber, coal powder, activated carbon powder, charcoal powder and coke. Preferably, when a carbonaceous raw material having a small H / C and O / C, that is, a raw material having H / C and O / C <10 ^-2 (molar ratio) is used, the heteroatom-containing fullerenes can be obtained at a higher yield. You can get it. Examples of such a raw material include graphitized carbon black, graphite powder, graphitized carbon fiber and the like.

Further, the metal element is preferably an element having a small ionic radius, specifically, lithium, potassium,
Alkali metals such as sodium, rubidium and cesium,
Group IIIa metals such as scandium, yttrium, and lanthanum; lanthanoids such as neodymium, samarium, europium, terbium, and ytterbium; and fourth-period transition metals such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, and zinc Can be mentioned.
These metal elements, even when used alone, are oxides, halides, carbonates, bicarbonates, oxalates, sulfides,
You may use as compounds, such as a sulfate and a nitrate. When a simple substance or a compound of these metal elements is used, a fullerene in which a hetero atom is added to a fullerene composed only of carbon atoms is produced.

On the other hand, when a simple substance or a compound of an element selected from the group consisting of boron, nitrogen, phosphorus and silicon is used, a fullerene in which a hetero atom is added to a fullerene composed only of carbon atoms is produced. In some cases, these elements occupy a position very close to carbon on the periodic table, and since their properties are similar to those of carbon, they are often replaced with carbon atoms of fullerenes. Therefore, fullerenes in which some carbon atoms of the fullerenes composed only of carbon atoms are replaced with hetero atoms will be produced.

Specifically, in addition to elemental boron, nitrogen gas, elemental phosphorus and silicon, boron carbide, boron nitride, boric acid,
Diborane, boron chloride, borazine, nitrogen-containing hydrocarbons such as ammonia, pyridine and quinoline, nitric oxide, nitrogen oxides such as nitrogen dioxide, phosphoric acid, phosphine, boron phosphide, silica, monosilane, disilane, monochlorosilane, Dichlorosilane, trichlorosilane, trimethylsilane, triethylsilane, etc.Oxygen, hydrogen, carbon and /
Alternatively, a compound with halogen is preferable.

And these metal elements, boron, nitrogen,
Heteroatom-containing fullerenes are produced by introducing a simple substance of one or more elements selected from the group consisting of phosphorus and silicon, or a compound thereof, and a carbonaceous raw material into the thermal plasma zone for vapor decomposition and re-precipitation. 2 from the group consisting of metallic elements, boron, nitrogen, phosphorus and silicon
It is needless to say that the heteroatom-containing fullerenes can be produced without any particular problems even when one or more species are simultaneously introduced into the thermal plasma region.

The simple substance or compound of these elements and the carbonaceous raw material may be in the form of powder, fibrous material, gasification of a highly sublimable organometallic compound or introduction of nitrogen gas. It may be a gas, and a liquid compound may be used as the mist. That is,
It is not particularly limited as long as it can be easily evaporated by heating in thermal plasma, but for that purpose, the particle size (JIS K-0302-198) in these raw materials is used.
9 It is preferable that substantially no particles having a particle size distribution of 100 μm or more) are substantially contained in the exhaust gas. More preferably 60 w for particles less than 20 μm
It is better to contain t% or more, and most preferably to introduce into the thermal plasma in a floating state containing particles of less than 10 μm in an amount of 60 wt% or more. Ordinary powders exist in agglomerated state, so in order to suspend the above fine particles, a method of combining a classifier such as a cyclone, if necessary, via a jet crusher or a disperser using a high-speed rotor. There is.

The source of the thermal plasma used in the present invention is not particularly limited as long as it generates a thermal plasma having a high thermal conductivity and a long residence time at a temperature high enough to vaporize carbon. Specific examples include a DC jet, a high frequency inductively coupled plasma, a hybrid type of a DC jet and a high frequency inductively coupled type, a hybrid type in which two or three high frequency inductively coupled plasmas are arranged in series.

If these plasma sources are used, 40
It is possible to generate thermal plasma having a sufficiently high thermal conductivity and residence time at 00 to 20000 ° C., and a sublimation point of about 35.
Carbon at 50 ° C evaporates easily. Further, almost all metals and metal compounds are decomposed and vaporized to generate vapors of metal ions. However, in the present invention, even with the same thermal plasma, the higher thermal conductivity and the longer residence time increase the evaporation efficiency of the carbon source and the metal or metal compound,
In addition, the deposition efficiency of the metal-containing fullerene can be improved, and for that purpose, the system pressure is preferably 10 torr or more, more preferably 50 torr or more. On the other hand, if the pressure of the system is too high, the plasma generation is adversely affected. Therefore, the pressure is preferably 2 atm or less, more preferably 1.5 atm or less.

Among the above thermal plasma sources, a high frequency inductively coupled plasma or a hybrid plasma in which it is superposed with a DC jet or a small high frequency inductively coupled plasma is preferable because it has a longer residence time. The lower limit of the introduction amount of the carbon raw material and the metal or the metal compound is an amount capable of depositing and recovering a sufficient amount of the metal-containing fullerene, and the upper limit is such that the plasma does not disappear and a sufficient amount of heat for vaporization can be obtained. If The upper limit depends on the input power for forming the thermal plasma flow zone and the plasma generation method. For example, in the case of the high frequency induction type plasma, when the input power is 20 KW, the upper limit is 10 g.
/ Min or less, and in the case of 50 KW, it may be 100 g / min or less.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist thereof. <Example 1> In the hybrid type plasma reactor shown in FIG. 1, the input power was 5 KW for the DC arc 1 and 17 KW (4 MHz) for the high frequency arc 2. Argon in a swirling flow from the gas inlet 3 for DC arc 26 Nl / m
in, 12 N of argon in the radial direction from the gas inlet 4
1 / min and helium were premixed at 14 Nl / min and introduced from the gas introduction port 6, respectively. A filter is installed downstream and connected to a vacuum pump via a flow control valve, and the system internal pressure is adjusted to 600 torr by adjusting the valve opening.
Kept at.

The raw material is carbon black (# made by Mitsubishi Kasei
4000 B) at 2 g / min and Y ₂ O ₃ at 0.4 g / mi
n was simultaneously entrained in an Ar gas flow of 10 Nl / min, and the particle-containing gas was collided and dispersed on the metal plate, and then 1 in a gravity classification tank.
After removing particles having a diameter of 00 μm or more, the particles were introduced through the fine powder introduction port 5 above the plasma. The particle size of suspended particles in this gas was measured based on JIS K-0302-1989, and it was found that 75% of particles having a particle size of less than 10 μm were contained. Carbon black and Y ₂ O ₃ are completely decomposed in plasma, and carbonaceous and metal-containing carbonaceous materials and metal compounds are re-deposited downstream.

As for the product, the adhered portion on the chamber wall on the downstream side and the collected portion on the filter installed further downstream were recovered. When this was extracted with toluene, a reddish purple extract was obtained. It was confirmed by ESR and elemental analysis that the extract contained yttrium, and
72 when checked by orption Mass spectrometer
0 (C ₆₀ ), 840 (C ₇₀ ), 1008 (C ₈₄ ), 10
1073 amu corresponding to YC ₈₂ and 116 corresponding to Y ₂ C ₈₂ along with peaks of fullerenes such as 80 (C ₉₀ ) amu.
2 amu peak and 1186 am corresponding to Y ₂ C ₈₄
The u peak appeared.

The recoveries of YC ₈₂ , Y ₂ C ₈₂ and Y ₂ C ₈₄ were each about 2% with respect to the total weight sum of the recovered fullerenes. <Example 2> The same experiment as in Example 1 was carried out except that 5% of calcium carbonate was mixed with carbon black # 4000B manufactured by Mitsubishi Kasei Co., Ltd. as a raw material. As a result, about 2% of a toluene extract was obtained from the recovered solid. It was confirmed by elemental analysis that the extract contained calcium, and C was confirmed by mass spectral analysis.
aC ₆₀ , Ca ₂ C ₆₂ , CaC ₆₆ , CaC ₇₈ , CaC ₈₄ ,
The peak of Ca ₂ C ₈₂ was detected.

Example 3 Carbon black # 4000B manufactured by Mitsubishi Kasei Co., Ltd. was used as a raw material with 5% of metal yttrium powder.
The same experiment as in Example 1 was carried out except that the mixture was used. As a result, about 3% toluene extract was obtained from the recovered solid. It was confirmed by ESR and elemental analysis that the extract contained yttrium, and YC ₈₂ , Y ₂ C ₈₂ , Y ₂ C ₈₄ and YC ₈₂ , Y ₂ C ₈₄ , Y were confirmed by mass spectral analysis.
C ₆₀ , a corresponding peak was detected.

Example 4 The same experiment as in Example 2 was carried out except that 5% of iron powder was mixed with carbon black # 4000B manufactured by Mitsubishi Kasei Co., Ltd. as a raw material. As a result, about 3% toluene extract was obtained from the recovered solid. The extract was confirmed to contain iron by elemental analysis, and Fe was confirmed by mass spectrometry.
₂ C ₆₀ , FeC ₇₂ , FeC ₈₀ , Fe ₂ C ₈₂ , and corresponding peaks were detected.

<Example 5> The same experiment as in Example 1 was conducted except that carbon black # 4000B manufactured by Mitsubishi Kasei Co., Ltd. containing 2% of hexagonal boron nitride was used as a raw material. As a result, about 5% toluene extract was obtained from the recovered solid. It was confirmed by elemental analysis that the extract contained boron, and by mass spectrometry, C ₅₉ B, C ₅₈ B ₂ , C ₅₇ B ₃ , C ₅₆ B ₄ and corresponding peaks were detected. It was

<Example 6> As a raw material, a Mitsubishi Kasei Co.
Carbon black # 4000B, Argo in plasma
25Nl / min mixed with 0.1Nl / min nitrogen
Then, the gas is introduced from the gas introduction port 4, and again in the radial direction with argon.
Is introduced from the 23Nl / min gas inlet 6
The same experiment as in Example 1 was conducted. As a result, whether it is in the recovered solid
To obtain about 5% toluene extract. Nitrogen in this extract
Is confirmed by elemental analysis, and
C by mass spectrometry₅₉N, C₅₈N₂, C
₅₇N₃, C ₅₆N_Four, A considerable peak was detected.

[0025]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to continuously and in large quantity produce heteroatom-containing fullerenes, and it is possible to use them for catalysts, electronic materials, reaction reagents, optical materials and the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a hybrid plasma reactor used in the present invention.

[Explanation of symbols]

 1-DC arc 2--high frequency arc 3,4,5,6,7--gas introduction port 8--cooling water introduction pipe 9--cooling water distribution pipe

Claims (5)

[Claims] 1. A simple substance of one or more elements selected from the group consisting of metallic elements, boron, nitrogen, phosphorus and silicon, or a compound thereof, and a carbonaceous raw material are introduced into a thermal plasma zone to be vaporized and decomposed and then re-deposited. A method for producing a heteroatom-containing fullerene, which comprises: 2. The method according to claim 1, wherein fullerenes are produced by adding a hetero atom to a fullerene composed of only carbon atoms. 3. The method according to claim 1, wherein fullerenes are produced by substituting a part of carbon atoms of fullerenes composed of only carbon atoms with heteroatoms. 4. The method according to claim 2 or 3, wherein the hetero atom is one or more elements selected from the group consisting of boron, nitrogen, phosphorus and silicon. 5. A simple substance of the element or a compound thereof and a carbonaceous raw material are substantially free of particles having a particle size of more than 100 μm and are introduced into the thermal plasma zone in a floating state. 5. The manufacturing method according to any one of 4 to 4.