JP5119219B2 - Method for producing carbon fine particles - Google Patents

Description

  The present invention relates to a method for producing carbon fine particles, particularly carbon fine particles containing a high yield of fullerenes.

Carbon particles, particularly as a conventional method for producing fullerenes, for example, in Patent Document 1, is that the carbon-containing material (hydrocarbon compound) can be produced fullerenes by collecting agglutination was burned in a flame Are listed. That is, fullerenes are contained in soot-like substances generated in the combustion process.

  In order to improve the yield of fullerenes contained in soot-like substances, it is effective to raise the flame temperature, perform combustion under reduced pressure, and dilute the atmosphere with an inert gas such as argon. It is known that

Patent document 2 discloses a method for producing fullerenes with high productivity by decomposing and exploding unsaturated hydrocarbon gases such as acetylene and ethylene. However, such a method has a yield of fullerenes. As low as 3%. The reason for this is that when the decomposition reaction of acetylene and ethylene is the main reaction, as shown below, the reaction pressure (gas pressure) is almost unchanged (in the case of acetylene) or conversely (in the case of ethylene). This is probably because the reaction cannot be performed in a reduced pressure state.
C ₂ H ₂ (g) → 2C (s) + H ₂ (g)
C ₂ H ₄ (g) → 2C (s) + 2H ₂ (g)

In addition, even when oxygen is added to an unsaturated hydrocarbon gas such as acetylene or ethylene to cause the combustion reaction shown below to occur simultaneously with the above decomposition reaction, it occurs in the technique disclosed in Patent Document 2. Since there is no water vapor condensation mechanism, the reaction pressure (gas pressure) is almost unchanged by changing only the difference between the number of moles of the disappearing compound (gas) and the number of moles of the generated compound (gas) excluding the solid (the ethylene pressure). In the case of acetylene), it is difficult to maintain a reduced pressure state, particularly a reduced pressure state of 90 kPa or less.
C ₂ H ₂ (g) + 2.5O ₂ (g) → 2CO ₂ (g) + H ₂ O (g)
C ₂ H ₄ (g) + 3O ₂ (g) → 2CO ₂ (g) + 2H ₂ O (g)

  On the other hand, carbon black is also a soot-like substance, and such carbon black is generally blown into a reaction furnace lined with refractory bricks with air and raw materials such as gas, heavy oil, creosote oil, etc. Manufactured by incomplete combustion or thermal decomposition at about normal pressure and a high temperature of about ℃.

  Therefore, soot-like substances produced by partial combustion of hydrocarbon compounds such as gases and oils at different temperatures are usually different, but are usually fullerenes and a mixture of carbon black or carbon black-like substances. It is assumed that there is. That is, although it is very few, it is guessed that fullerenes also exist.

“Fullerenes” as used herein is a generic name for the third carbon form after diamond and graphite, and specific structures thereof include, for example, a 5-membered ring and a 6-membered ring as represented by C ₆₀ , C ₇₀ and the like. It is a hollow shell-like carbon molecule closed by a network of member rings. In recent years, it is expected to be applied to superhard materials, superconducting materials, semiconductor materials, pharmaceuticals, etc. It is desired to develop mass production technology.

Japanese National Publication No. 6-507879 JP-A-5-70115

  As a means for improving the yield of carbon fine particles such as fullerenes, as described above, it is useful to satisfy the three requirements of high flame temperature, high vacuum (reduced pressure), and dilution gas addition. It has been difficult to satisfy all these requirements by the conventional manufacturing method.

  That is, in order to obtain a high flame temperature, it is necessary to increase the amount of combustion heat generated by increasing the amount of introduction of hydrocarbon compounds (carbon-containing materials) as raw materials and fuel into the reactor. Increasing the amount of compound introduced results in an increase in the amount of exhaust gas generated by combustion, which hinders the condition of high vacuum. In addition, the addition of dilution gas will also inhibit high vacuum. In this case, in order to achieve a high vacuum, it is necessary to provide a large pressure reducing device, which causes a problem that the manufacturing cost increases.

  The object of the present invention has been made in view of the above points, and provides a method for producing carbon fine particles, particularly carbon fine particles containing high yield fullerenes, which can be made compact.

In order to solve the above-described problem, a method for producing carbon fine particles according to the present invention introduces a mixture containing a hydrocarbon compound and hydrogen, and an oxygen-containing gas into a reaction furnace, so that hydrogen, some hydrocarbon compounds, and A combustion reaction is caused with oxygen to generate a high-temperature gas of 1200 to 2000 ° C. composed of carbon dioxide and water vapor, and the remaining hydrocarbon compound introduced into the reactor using the heat of this high-temperature gas is 90 kPa or less. of upon by causing thermal decomposition reaction under a reduced pressure atmosphere to produce a carbon fine particles, a heat exchanger in communication with the reactor provided to cool the flue gas discharged from the reactor in the heat exchanger, the water vapor in the exhaust gas is condensed into water, the reaction furnace is reduced than the amount of exhaust gas discharged to the exhaust gas amount in the heat exchanger from the reactor to be Rukoto reduced pressure atmosphere.

In the present invention, it is more preferable to provide a pressure reducing means communicating with the heat exchanger .
Furthermore, in the present invention, the hydrocarbon compound preferably contains at least 5% by mass of oil.
Furthermore, in the present invention, it is more preferable that the hydrocarbon compound and / or the hydrogen is preheated to 500 to 1000 ° C. before being introduced into the reaction furnace.
In addition, in the present invention, the oxygen-containing gas preferably contains an inert gas.

  By the production method of the present invention, the production facility can be made compact, and carbon fine particles, in particular, carbon fine particles containing a high yield of fullerenes can be produced in large quantities and easily. In addition, because of the high yield, there is an advantage that separation and purification of fullerene becomes easy.

It is a flowchart which shows the manufacturing process of the basic carbon particle based on this invention . It is a flowchart which shows the manufacturing process of the other basic carbon particle based on this invention . It is a flowchart which shows the manufacturing process of the other basic carbon particle based on this invention . It is a flowchart which shows the manufacturing process of the carbon fine particle according to this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing a basic manufacturing process of carbon fine particles based on the present invention .

The carbon microparticle production process shown in FIG. 1 mainly includes a raw material mixing process 1, a carbon microparticle production process (reactor) 2, a cooling process 3, and a collection process 4.

  The raw material mixing step 1 is a step of mixing a mixture containing a hydrocarbon compound and hydrogen and an oxygen-containing gas.

The hydrocarbon compound is preferably an unsaturated hydrocarbon gas such as acetylene or ethylene, or a saturated hydrocarbon gas such as methane. Further, it may contain an oil component that is a liquid such as light oil, naphthalene, and tar. In particular, it is preferable that the hydrocarbon compound contains at least 5% by mass of oil in order to further increase the yield of fullerenes contained in the carbon fine particles.
In the present invention, “oil” means a hydrocarbon compound having a boiling point exceeding normal temperature (20 ° C.).

  Containing hydrogen means containing 1% by mass or more of hydrogen. In addition to pure hydrogen gas, the mixture preferably contains a gas generated in a coke oven or a gas generated by pyrolysis or gasification of organic matter such as waste plastic.

  The oxygen-containing gas is specifically air, but the amount of nitrogen gas unrelated to the reaction is reduced to reduce the total amount of exhaust gas generated in the reactor, and the reduced-pressure atmosphere in the reactor is simplified. It is preferable that the oxygen-enriched air in which pure oxygen or oxygen concentration is increased is used.

  The raw material mixing step 1 is not inconvenient even if it is performed in one place, but in particular, the carbon fine particle generation step is a mixture containing hydrogen and hydrocarbon compounds generated in a pyrolysis process, gasification process, or iron coke oven. In the case of direct introduction up to 2 (reactor), the temperature drops and the oil contained in the hydrocarbon compound does not adhere to the inner wall, or the oxygen-containing gas is blown in too much to overheat. In order to prevent the reaction from starting, it is preferable to introduce it at a plurality of appropriate locations while maintaining the temperature. In addition, it is more preferable to introduce an oxygen-containing gas necessary for heating to the reaction temperature immediately before or after the carbon fine particle production step 2 (reaction furnace). The raw material mixing step 1 may be performed together in the carbon fine particle generation step 2 (reactor).

  The carbon fine particle production step 2 is performed in a reaction furnace having a fireproof (heat-resistant) structure, such as a sealed structure that can withstand pressure reduction and a lining made of refractory bricks such as a high alumina material.

  The carbon fine particle generation step 2 is a step in which a combustion reaction and a thermal decomposition reaction are simultaneously generated. Specifically, a mixture containing a hydrocarbon compound and hydrogen and an oxygen-containing gas are introduced into a reaction furnace, and hydrogen is generated. In addition, a combustion reaction is caused with some hydrocarbon compounds and oxygen to generate a high-temperature gas of 1200 to 2000 ° C. composed of carbon dioxide and water vapor, and introduced into the reactor using the heat of this high-temperature gas. The remaining hydrocarbon compound undergoes a pyrolysis reaction under a reduced pressure atmosphere of 90 kPa or less.

  Here, the reason why the temperature of the high-temperature gas generated by the combustion reaction was set to 1200 to 2000 ° C. is that if it is less than 1200 ° C., the pyrolysis reaction rate becomes slow and the productivity of the carbon fine particles deteriorates. This is because a large amount of fuel is burned in order to maintain a high temperature, causing an increase in the amount of exhaust gas generated and making it difficult to form a reduced-pressure atmosphere.

  The reason why the thermal decomposition reaction is performed in a reduced-pressure atmosphere of 90 kPa or less is that if it exceeds 90 kPa, the proportion of carbon blacks in the produced carbon fine particles increases and the yield of fullerenes decreases. .

  In addition, as a means for creating a reduced pressure atmosphere in the reaction furnace, for example, as shown in FIG. 1, a cooling process 3 (cooling chamber) communicating with the carbon fine particle generation process 2 (reaction furnace) is provided. The exhaust gas discharged from the reactor is cooled in a cooling process, water vapor in the exhaust gas is condensed into water, the amount of exhaust gas in the cooling chamber is reduced from the amount of exhaust gas discharged from the reactor, and the reaction furnace is decompressed atmosphere It is preferable to make it. Furthermore, as shown in FIG. 2, a decompression means 5 that communicates with the cooling step 3 (cooling chamber) via the collecting step 4 may be provided. Further, as a means for making the inside of the reaction furnace a reduced pressure atmosphere, for example, as shown in FIG. 3, there is provided a decompression means 5 that communicates with the carbon fine particle generation process 2 (reaction furnace) through a collection process 4 to react. It is preferable to make the inside of a furnace into a reduced pressure atmosphere. As the decompression means 5, a known technique such as a vacuum pump may be used, and any method may be used.

  The oxygen-containing gas preferably contains an inert gas such as argon, helium, or neon in terms of improving the yield of fullerenes. That is, by diluting the oxygen-containing gas with an inert gas, the speed of the combustion reaction and the thermal decomposition reaction is slowed, and as a result of regular arrangement of C, fullerenes are likely to be generated.

  The content of the inert gas is preferably in the range of 10 times or less, more preferably in the range of 3 to 6 times the molar ratio with respect to oxygen.

The preheating of the oxygen-containing gas is not particularly limited, but it may be desirable to preheat for reasons such as an increase in flame temperature.

  In the cooling step 3, it is preferable to cool the metal surface that has been passed through with cooling water or the like by bringing a high-temperature gas containing carbon fine particles generated in the reactor into contact with the metal surface. May be. As a result of this cooling, as shown below, water vapor (gas) contained in the high-temperature exhaust gas generated in the reactor is condensed into water (liquid). As a result, it was introduced in any case of methane, acetylene and ethylene. As a result of greatly reducing the number of moles of gas and reducing the amount of gas in the cooling chamber, a reduced pressure atmosphere in the reactor can be created.

In particular, in the present invention, the combustion reaction in the reactor is performed not only by adding hydrocarbon compounds and oxygen, but also by actively adding hydrogen as a fuel, thereby increasing the number of moles of water vapor generated. , Increase the pressure reduction effect due to condensation in water. That is, the gas pressure when methane, acetylene and ethylene are used as the hydrocarbon compound gas is 4.5 mol to 1 mol, 5 mol to 2 mol and 5.5 mol, respectively, as is apparent from the reaction formula shown below. 2 moles. Of these hydrocarbon compound gases, it is particularly preferable to use methane, which has a large reduction rate of gas pressure due to condensation of water vapor (gas) into water (liquid) as the hydrocarbon compound gas.
CH ₄ (g) + 2.5O ₂ (g) + H ₂ (g) → CO ₂ (g) + 3H ₂ O (l)
C ₂ H ₂ (g) + 3O ₂ (g) + H ₂ (g) → 2CO ₂ (g) + 2H ₂ O (l)
C ₂ H ₄ (g) + 3.5O ₂ (g) + H ₂ (g) → 2CO ₂ (g) + 3H ₂ O (l)

In the thermal decomposition reaction when methane, acetylene and ethylene are used as the hydrocarbon compound gas, hydrogen gas is generated as shown below, and such hydrogen gas is used for the combustion reaction.
CH ₄ (g) → C (s) + 2H ₂ (g)
C ₂ H ₂ (g) → 2C (s) + H ₂ (g)
C ₂ H ₄ (g) → 2C (s) + 2H ₂ (g)

  For the collection step 4, a known device such as a bag filter or a cyclone can be used.

Moreover, in this invention, it is preferable to preheat to 500-1000 degreeC before introduce | transducing the hydrocarbon compound and / or hydrogen which are contained in the said mixture in a reaction furnace. Preheating is preferable in that the reaction in the reactor is promoted and the amount of carbon fine particles generated is increased, so that the amount of the mixture containing the hydrocarbon compound and hydrogen can be reduced. In the case of using a vacuum pump as a vacuum hand stage, the load on the vacuum pump is further reduced, leading to miniaturization of the vacuum pump. Furthermore, preheating may be either a hydrocarbon compound alone, hydrogen alone, or both a hydrocarbon compound and hydrogen, but in particular preheat both a hydrocarbon compound and hydrogen, ie a mixture containing both. Is most preferable because the above-described effects can be obtained to the maximum.

The present invention is characterized in that a heat exchanger is used as the above-described cooling chamber.
FIG. 4 is a flowchart showing an embodiment of a process for producing carbon fine particles according to the present invention .
As shown in FIG. 4, the carbon fine particle manufacturing process of the present invention has the configuration shown in FIG. 2 except that a heat exchange process 6 (heat exchanger) is provided instead of the cooling process 3 (cooling chamber). is substantially similar, high temperature exhaust gas generated in the reaction furnace, together with contributing is cooled in a heat exchange step for the generation of reduced pressure atmosphere, using a high temperature waste heat obtained in the heat exchange process, hydrogen and hydrocarbons The structure which preheats the mixture containing a hydrogen compound is employ | adopted, and, thereby, thermal efficiency improves and it can aim at energy saving. In FIG. 4, heat exchange with the high-temperature combustion exhaust gas is performed, but preheating may be performed by providing a separate heat exchanger.

  The preheating temperature of the hydrogen and / or hydrocarbon compound contained in the mixture may be several hundred degrees Celsius or higher, but in order to increase the flame temperature and obtain stable combustion, it is preferably 500 degrees Celsius or higher, and 1000 If it exceeds ℃, a thermal decomposition reaction is likely to occur and carbon particles start to be generated.

  In the present invention, it is preferable to use a hydrocarbon compound containing hydrogen and oil discharged from a pyrolysis process, gasification process, or iron-making coke oven as a fuel or a raw material. The carbon fine particles contained in a high yield can be produced at a lower cost. Furthermore, the use of waste containing organic substances as fuel or raw material is advantageous because it can be manufactured at a lower cost.

  The above description only shows an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

(Example 1)
According to the manufacturing process shown in FIG. 4, and hydrogen indicated in Table 1, methane, crude coke oven gas containing a hydrocarbon compound gas oil and naphthalene, was preheated to 600 ° C., oxygen diluted 5-fold with argon gas It was introduced into a reaction furnace, and hydrogen, methane, and the like in the crude coke oven gas were burned to bring the inside of the reaction furnace to 1800 ° C. to cause a pyrolysis reaction, thereby producing carbon fine particles. The reactor downstream of, together with the condensing steam produced by the combustion is cooled by the heat exchanger hot gas containing carbon fine particles and sucked by a vacuum pump, maintaining the reaction furnace atmosphere 30 kPa. As a result of analyzing the amount of fullerenes in 100 g of the carbon fine particles collected in the collecting step, it was 12 g (yield of fullerenes: 12%).

(Example 2)
According to the production process shown in FIG. 4, the main component composition containing methane as a hydrocarbon compound is adjusted to 8.6% by mass of hydrogen, 38.6% by mass of methane, 13.5% by mass of carbon monoxide, 7.0% by mass of carbon dioxide, and 4.5% by mass of nitrogen. Carbon fine particles were produced under the same conditions as in Example 1 except that the gas used was a raw material. As a result of analyzing the amount of fullerenes in 100 g of the carbon fine particles recovered in the collecting step, it was 8 g (yield of fullerenes: 8%).

(Comparative Example 1)
The water shown in Table 2 obtained by providing a branch pipe on the coke oven riser pipe in accordance with the manufacturing process shown in FIG. And coke oven gas at 920 ° C containing methane, light oil and tar hydrocarbon compounds Oxygen diluted 10-fold with argon gas was introduced into the reactor, and hydrogen in the coke oven gas and Combustion of methane, etc. to bring the inside of the reactor to 1600 ° C, causing a pyrolysis reaction to produce carbon particles did. On the downstream side of the reactor, high-temperature gas containing carbon particles is cooled by a cooling process for combustion. The resulting water vapor is condensed and sucked with a vacuum pump, so that the atmosphere in the reactor is normal pressure. (About 100 kPa). The amount of fullerenes in 100 g of carbon fine particles collected in the collection process As a result of analysis, it was 0.1 g or less (yield of fullerenes: 0.1% or less).

  By the production method of the present invention, the production facility can be made compact, and carbon fine particles, particularly carbon fine particles containing a high yield of fullerene can be produced in large quantities and easily.

1 Mixing process
2 Carbon fine particle production process (or reactor)
3 Cooling process (or cooling room)
4 Collection process
5 Pressure reduction process (or pressure reduction means)
6 Heat exchange process (or heat exchanger)

Claims (5)

A hydrocarbon compound and a mixture containing hydrogen and an oxygen-containing gas are introduced into a reaction furnace, and a combustion reaction is caused by hydrogen, a part of the hydrocarbon compound and oxygen, and the temperature is 1200 to 2000 ° C. composed of carbon dioxide and water vapor. When producing carbon fine particles by generating a pyrolysis reaction of the remaining hydrocarbon compound introduced into the reactor using the heat of the high-temperature gas in a reduced-pressure atmosphere of 90 kPa or less. ,
A heat exchanger communicating with the reaction furnace is provided, exhaust gas discharged from the reaction furnace is cooled by the heat exchanger, water vapor in the exhaust gas is condensed into water, and the amount of exhaust gas in the heat exchanger is converted to the reaction A method for producing carbon fine particles, characterized by reducing the amount of exhaust gas discharged from the furnace to a reduced pressure atmosphere in the reaction furnace.   2. The method for producing carbon fine particles according to claim 1, further comprising a decompression unit communicating with the heat exchanger.   The method for producing carbon fine particles according to claim 1 or 2, wherein the hydrocarbon compound contains at least 5 mass% of oil.   The method for producing carbon fine particles according to any one of claims 1 to 3, wherein the hydrocarbon compound and / or the hydrogen is preheated to 500 to 1000 ° C prior to introduction into the reactor. .   The method for producing carbon fine particles according to any one of claims 1 to 4, wherein the oxygen-containing gas contains an inert gas.

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