JPH05116922A - Method and device for refining fullerenes - Google Patents

Abstract

PURPOSE:To continuously separate and refine a mixture of fullerenes in bulk and to separately recover C60, C70, C76, C78, C84, C90, C96, etc. CONSTITUTION:Belts 22 endlessly rotated by hot rollers 23 and cold rollers 24, and heated and cooled, are provided in a chamber 20 in multiple stages, a heater 21 (or heat exchanger) is installed at the lowermost stage, and a cooled belt 22 is arranged at the uppermost stage. The heating temps. T1, T2,... of the respective stages are successively decreased toward the downstream side. As a result, the fullerenes having higher sublimation point are collected by the belts 22 at the lower stage, scraped by a blades 25 and introduced into storage chambers 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for purifying fullerenes, and more particularly to a method and apparatus for purifying fullerenes capable of separating C ₆₀ , C _{70 and the} like with high purity.

[0002]

BACKGROUND OF THE INVENTION Fullerenes are C ₆₀ , C ₇₀ , C ₇₆ ,
It is a high carbon number closed shell carbon allotrope such as C ₇₈ , C ₈₄ , C ₉₀ and C ₉₆ . C ₆₀ has a truncated icosahedron soccer ball-like lattice structure.

In a conventional apparatus for producing fullerenes, a graphite-based cathode and an anode made of a graphite rod are installed in a reaction chamber, and when arc discharge is performed in an atmosphere of He of about 100 Torr, carbon evaporated from the anode is He. Quenched,
Soot (soot) containing fullerenes such as C ₆₀ is produced. This soot adheres to the surface of the water-cooled recovery plate and is collected.

The collected reaction product is extracted with a Soxhlet extractor or the like and then separated into C ₆₀ , C _{70 and the} like by a separation method such as liquid chromatography.

In addition, J. Phys. Chem.95
Fullerene C in (8), 2994 (1991)₆₀as well as
C₇₀The physical property data in the heating sublimation of the are shown.

[0006]

The method for separating allotropes by liquid chromatography has a problem that the processing speed is extremely slow, it is not suitable for mass production, and the apparatus is extremely expensive when it is attempted to be automated. ..

Further, in the conventional sublimation separation method, since sublimation separation is carried out in a single stage, there is a problem that the allotrope is not sufficiently fractionated and high-purity separation cannot be performed.

[0008]

A method for purifying fullerenes according to claim 1 is a method of heating a crude fullerene raw material to vaporize the fullerenes and depositing vapors of the fullerenes on a low temperature collecting member. A purification method for fullerenes, comprising: a purification step; and a higher-order purification step in which steam of the fullerenes generated by heating the fullerenes on the collection member is deposited on another collection member. The heating temperature of the fullerenes in the subsequent purification step is lower than that in the primary purification step, and fullerenes having different sublimation temperatures are separated.

A method for purifying fullerenes according to a second aspect is the method and apparatus for purifying fullerenes according to the first aspect, wherein the higher-order purification step is performed a plurality of times and the heating temperature of the fullerenes in the higher-order purification step is changed. The lower the process, the lower
It is characterized in that a large number of fullerenes having different sublimation temperatures can be separated.

According to a third aspect of the present invention, in the apparatus for purifying fullerenes, the first fullerene raw material is heated to vaporize the fullerene and the first heater is contacted with vaporized gas from the first heater to form fullerene on the surface. A belt to be deposited, a plurality of rollers arranged to rotate the belt endlessly, a belt heater provided on some rollers, a belt cooler provided on other rollers, and deposits from the belt A fullerene sublimation device provided with a means for peeling off, and a collection member for cooling and precipitating vaporized gas from the sublimation device, and the heating temperature of the belt heater of the fullerene sublimation device, It is characterized by being lower than the heating temperature of the heater.

The fullerene purifying apparatus according to claim 4 is the fullerene purifying apparatus according to claim 3, wherein the plurality of fullerene sublimation devices are connected in series so that vaporized gas is sequentially supplied. The belt heaters of these fullerene sublimation devices are characterized by a lower heating temperature toward the downstream side in the gas flow direction.

[0012]

In the method for purifying fullerenes according to claim 1 and the apparatus for purifying fullerenes according to claim 3, since the fullerenes undergo sublimation separation treatment in multiple stages, allotropes can be separated with high purity.

In the apparatus for purifying fullerenes according to claim 3, the fullerenes in the air adhere to the portion of the belt cooled by the belt cooler. When the belt is heated by the belt heater, the attached fullerenes are heated, and the low sublimation point component therein is vaporized.

In the method for purifying fullerenes according to claim 2 and the apparatus for purifying fullerenes according to claim 4, since sublimation separation of fullerenes is carried out in at least three stages or more, a large number of fullerene allotropes are separated with high purity. it can.

[0015]

EXAMPLES Examples will be described below with reference to the drawings. FIG. 1 is a system diagram showing a batch type fullerene refining apparatus, and a large number (n units) of sublimation units 1, 2, ...
Is installed. Each of the sublimation units 1, 2, ... N includes a chamber 11, a heating table 12 and a cooler 13 provided in the chamber 11. The heating table 12 is provided with a heater or a heat exchanger 14, and is configured to heat the fullerenes placed on the table 12. 15 is a pipe for transferring fullerenes to a higher-order sublimation unit, 16 is a pipe for returning fullerenes to a lower-order sublimation unit, 17 is a pipe for taking out purified products, and 18 is an inert gas circulation A line, 19 is a filter provided in the middle of the line 18, 120 is an exhaust gas line, 121 is an exhaust pump (oil-free circulator), and 122 is a new gas supply line.

He, Ar, N ₂ or the like is used as the inert gas. The inside of the chamber 11 is maintained under normal pressure or a constant reduced pressure.

The heating table 1 of the first sublimation unit 1
The fullerene raw material is introduced on top of 2 and heated. As a result, according to the solid-gas equilibrium at this heating temperature, more fullerenes with lower sublimation points are evaporated. The generated steam is
It is cooled by the cooler in the upper part of the chamber and solidifies to become fine particles. This is the heating table 12 of the second sublimation unit.
Introduce on top and evaporate again. Not evaporated (first
All the (stage refined product) is returned to the first stage heating section, or a part thereof is taken out of the system through the pipe 17. Hereinafter, the same operation is performed from the second stage to the final stage sublimation units 2 to n. The heating temperature of each stage heating table 12 is set to gradually decrease from the first stage to the final stage. As a result, the purified products at each stage are analyzed and the C _{60 to} C at different sublimation temperatures are analyzed.
_{It is} a purified product containing most of each of _{96 and the} like. Each stage is
Each can be optimized by reducing the pressure and changing the heating and / or cooling part temperature. Generally, the larger the number of stages n, the higher the purity of each component.

FIG. 2 is a sectional view of a continuous refining apparatus according to an embodiment of the present invention.

The inside of the chamber 20 is N in order from the bottom to the top.
It is divided into a large number (n pieces) of separation zones of ₁ , N ₂ , N ₃ , .... A heater (heater or heat exchanger) 21 for fullerenes is installed in the first (lowermost) separation zone N ₁ .

Second to (n-1) th separation zones N
₂ , N ₃ ... N _n-1 are provided with a belt 22, a hot roller 23 and a cold roller 24 for rotating the belt 22 endlessly, and a blade 25 for peeling off adhered matters from the belt 22. There is. The hot roller 23 has a heater or a heat exchanger, and the cold roller 24 has a cooler.

In the uppermost (final) separation zone N _n ,
A belt 22, a cold roller 24 for endlessly rotating the belt 22 while cooling the belt 22, and a blade 25 for stripping off adhered matters from the belt 22 are provided.

First to (n-1) th separation zones N
₁ , N ₂ , ... N _n-1 have upper separation zones N ₂ , N ₃
A storage chamber 27 for storing the solid matter that has fallen from N _n is provided. The inlet to the storage chamber 27 can be opened and closed by a damper 29. A guide plate 30 for solid falling objects is provided so as to be continuous with the lower side of the blade 25. The solid matter in the storage chamber 27 can be taken out from a take-out port 31 with a lid.

A throttle 32 for preventing a short-circuit flow of gas is provided between the separation zones N ₁ , N ₂ , ... N _n .

The first-stage separation zone N ₁ is provided with openings 33 for charging a raw material and for extracting a solid residue.
A circulation line 34 for a rare gas such as He or Ar is provided between the final separation zone N _n and the first separation zone, and a filter 35 and an oil-free circulator 3 are provided on the way.
6, an exhaust gas line 37, and a rare gas supply line 38 are provided.

When the heating temperature of each separation zone N ₁ , N ₂ , ... N _n-1 is set to T ₁ , T ₂ , ... T _n-1 , the heating temperature becomes lower in the separation zone on the subsequent stage side. The temperature of the heater 21 and each hot roller 23 is set.

In the apparatus for purifying fullerenes thus configured, the raw material for fullerenes is charged in the separation zone N ₁ of the first stage and heated by the heater 21. The fullerenes contained in the raw material are evaporated, enter the separation zone N ₂ of the second stage, and are cooled by the cold roller 24.
2 is deposited on the surface. With the rotation of the belt 22,
The attached fullerenes are heated by the hot roller 23,
Fullerenes with a low sublimation point are evaporated and introduced into the _third separation zone N ₃ . Fullerenes having a high sublimation point remain on the belt 22 as they are and are peeled off by the plate 25.
The stripped fullerenes fall along the guide plate 30 and are introduced and stored in the lowermost storage chamber 27.

The fullerenes evaporated from the belt 22 in the second-stage separation zone N ₂ are introduced into the third-stage separation zone N ₃ and adhered to the belt 22, and the fullerenes having a low sublimation point therein. Is sent from the _third separation zone N ₃ to the upper separation zone, and the fullerene that has not sublimated is stripped off by the blade 25 and stored in the second storage chamber from the bottom.

In this way, each separation zone N ₁ , N ₂
The precipitation and evaporation are repeated in N _n , the fullerene having the lowest sublimation point adheres to the belt 22 in the uppermost separation zone N _n , and is stored in the uppermost storage chamber 27.

In this way, the fullerenes separated for each sublimation point are stored in each storage chamber 27 and taken out from the outlet 31 of each storage chamber 27.

When the purifying device for fullerenes is put into operation, both the following batch processing and continuous processing can be carried out.

Batch treatment Crude raw materials of fullerenes were put together into the first-stage separation chamber N _1, and after the separation of all of the input materials was completed, the solid residue was taken out from the first-stage separation chamber, if necessary, The crude material of the next batch is put into the separation chamber N ₁ of the first stage.

In the case of this batch processing, at the beginning of the separating operation, the damper 29 is tilted down so that the inlet is fully closed.
All the solid fullerenes that have been peeled off from the belt 22 on the upper stage and dropped may be returned to the lower stage. And
After a certain amount of time has passed since the separation operation was started and each fullerene was sufficiently isolated, the damper 29 may be opened to introduce the fallen objects into the storage chamber 27.

Alternatively, the damper 29 may be opened a little from the beginning so that a part of the falling object is taken into the storage chamber 27. Of course, the damper 29 may be fully opened from the beginning.

Continuous Treatment The device is continuously operated, the raw material is continuously or intermittently charged through the opening 33, and the fullerenes are continuously or intermittently taken out from each storage chamber 27. The residue is continuously or intermittently taken out from the first-stage separation zone N ₁ .

Also in this case, the damper 29 may be fully opened or may be slightly opened.

Specific working examples and comparative examples will be described below.

(Inventive Example) The raw material was separated using the apparatus shown in FIG.

The internal pressure in the chamber 20 is 1 atm and the number of stages is 5
Stages (n = 5), heating temperatures T ₁ , T ₂ , T ₃ and T ₄ were set to 750K, 735K, 725K and 710K respectively from the lower stage, and all cooler temperatures were set to room temperature.

As a raw material, a C ₆₀ / C ₇₀ = 4/1 mixture which was previously heat-treated in Ar at 200 ° C. for 24 hours was used as a first raw material.
It was continuously charged into the separation zone N _{1 of the} stage. As a result, impurities higher-order fullerenes as the lowermost non-volatile matter (residue),
In addition, in the first to fourth storage chambers 27, C ₇₀ : 90
%, C ₇₀ : 98%, C ₆₀ : 95%, C ₆₀ : 98% were obtained in the steady state. It took about 15 minutes to reach a steady state, and continuous operation was possible.

Comparative Example A single-stage sublimation separation was carried out at a heating section temperature of 720 K using only the first-stage separation zone N _{1. The} nonvolatile content was C ₇₀ : 71% and the purified product was C _60. :
It was about 93%, and sufficient separation was not possible.

[0041]

As described above, according to the method and apparatus for purifying fullerenes of the present invention, fullerenes can be separated and purified in a large amount and with high purity. Particularly, according to the method and the apparatus of claims 2 and 4, C ₆₀ , C
Can separate fullerenes other than ₇₀ with high accuracy.

[Brief description of drawings]

FIG. 1 is a system diagram of an apparatus according to an embodiment.

FIG. 2 is a cross-sectional view of another example device.

[Explanation of symbols]

 1, 2, 3, ... N Separation unit 11 Chamber 12 Heating table 14 Heater or heat exchanger 20 Chamber 21 Heater 22 Belt 23 Hot roller 24 Cold roller 25 Blade 27 Storage chamber 29 Damper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masafumi Matsumoto 1st Hachiman Kaigan Dori, Ichihara City, Chiba Mitsui Engineering & Shipbuilding Co., Ltd. Chiba Works

Claims (4)

[Claims] 1. A primary purification step of heating a fullerene raw material to vaporize fullerenes and deposit vapor of the fullerenes on a low temperature collecting member, and heating the fullerenes on the collecting member. A method for purifying fullerenes, comprising: a higher-purification step in which vapor of fullerenes generated by the above is deposited on another collection member, wherein the heating temperature of the fullerenes in the higher-purification step is higher than that in the first purification step. A method for purifying fullerenes, characterized in that fullerene having different sublimation temperatures is separated. 2. The method and apparatus for purifying fullerenes according to claim 1, wherein the higher-order purification step is performed a plurality of times, and the heating temperature of the fullerene in the higher-order purification step is lowered in the subsequent steps so that A method for purifying fullerenes, characterized in that a large number of different fullerenes can be separated. 3. A first heater that heats a fullerene raw material to vaporize fullerenes, a belt that is brought into contact with vaporized gas from the first heater and deposits fullerenes on the surface, and the belt is endless. Fullerene comprising a plurality of rollers arranged to rotate, a belt heater provided on a part of the rollers, a belt cooler provided on another roller, and a means for peeling the deposits from the belt. A sublimation device; and a collection member for cooling and precipitating vaporized gas from the sublimation device. The heating temperature of the belt heater of the fullerene sublimation device is
A device for purifying fullerenes, which is lower than the heating temperature of the heater. 4. The fullerene purifying apparatus according to claim 3, wherein a plurality of the fullerene sublimation devices are connected in series so that vaporized gas is sequentially supplied,
The belt heater of these fullerene sublimation devices is a device for purifying fullerenes characterized in that the heating temperature is lower toward the downstream side in the gas flow direction.