JP2021104918A - Reaction furnace and device for producing fullerene - Google Patents

Abstract

To provide a reaction furnace that can improve the yield of fullerene.SOLUTION: A reaction furnace is used for production of fullerene by a combustion method, the reaction furnace having, on its inner peripheral surface, a coating layer containing at least one selected from carbon material, silicon carbide and vanadium dioxide.SELECTED DRAWING: Figure 1

Description

The present invention relates to a reactor and an apparatus for producing fullerenes used for producing fullerenes by a combustion method.

As a method for producing fullerenes inexpensively and efficiently in large quantities, a combustion method for producing fullerenes by incompletely burning a carbon compound in a reaction furnace is known (for example, refer to Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-8456

However, even with a combustion method capable of producing a large amount of fullerene, it is difficult to further reduce the cost because the yield of fullerene is low. It is desired to improve the yield of fullerenes and reduce the production cost of fullerenes.

An object of the present invention is to provide a reactor capable of improving the yield of fullerene.

(1) A reactor used for producing fullerenes by a combustion method, the reactor having a coating layer containing at least one selected from a carbon material, silicon carbide and vanadium dioxide on the inner peripheral surface of the reactor.
(2) The reactor according to (1), wherein the area of the inner peripheral surface having the coating layer is 50% or more of the total area of the inner peripheral surface.
(3) The coating layer has a layer containing the carbon material and a layer containing at least one of the silicon carbide and vanadium dioxide covering the layer containing the carbon material in this order from the inner peripheral surface side. The reactor according to (1) or (2).
(4) A fullerene production apparatus having the reactor according to any one of (1) to (3).

According to the present invention, it is possible to provide a reactor capable of improving the yield of fullerene.

It is a figure which shows an example of the fullerene manufacturing apparatus of this embodiment. It is an enlarged view of the reactor part of the fullerene manufacturing apparatus of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, the featured parts may be enlarged and shown, and the dimensional ratios of the respective components may not be the same. ..

As shown in FIG. 1, the fullerene manufacturing apparatus 10 according to the present embodiment is connected to the reaction furnace 11 used for producing fullerene by the combustion method and the lower part of the fullerene reaction furnace 11 to generate the fullerene from the inside of the fullerene reaction furnace 11. A pipe 19 for passing a high-temperature exhaust gas having a soot-like substance containing the fullerene, a fullerene recovery device 16 for collecting the soot-like substance containing fullerene from the exhaust gas passing through the pipe 19, and a soot-like substance flowing out from the fullerene recovery device 16. A gas cooler 17 for cooling the gas from which the soot has been removed, and a decompression device 18 including a vacuum pump for sucking the gas cooled by the gas cooler 17 are provided. In the present invention, the description will be made with reference to FIGS. 1 and 2 as an example, but the present invention is not limited thereto. In FIG. 1, the reactor 11 is arranged in the vertical direction, and the raw material gas flows in from above, but it may be in the horizontal direction or the oblique direction. The reaction furnace 11 is preferably in the vertical direction, which is less affected by the retention of soot-like substances generated in the reaction furnace 11, and the fuel gas is preferably flowed in from above.

In the present embodiment, the reaction furnace 11 having an inner diameter of 10 cm and a length of 200 cm is used, but the present invention is not limited to this dimension, and a larger diameter reaction is used for mass production of fullerenes. It is also possible to use a furnace or a long reactor. A burner 13 for burning the supplied fuel gas under oxygen-containing gas is provided on the upstream side of the reaction furnace 11. Further, a heat insulating material 14 such as an alumina refractory brick or an alumina amorphous refractory material is lined on a part or all of the outside of the reactor 11.

The burner 13 is connected to the fuel gas pipe 20 for introducing the fuel gas and the oxygen-containing gas pipe 21 for introducing the oxygen-containing gas, and the fuel gas and the oxygen-containing gas are mixed at a predetermined mixing ratio to prepare a mixed gas. It has a chamber 13a, a pressure accumulator chamber 13b for holding the mixed gas at a predetermined pressure, and a mixed gas ejection portion 13c in which a large number of ejection ports are formed on a flat surface and the mixed gas is ejected vertically downward. The mixed gas ejection portion 13c may be composed of a porous ceramic sintered body or a powdered metal sintered body. It is preferable to preheat the fuel gas and the oxygen-containing gas supplied to the burner 13 by using a heat exchanger or the like. Further, the burner 13 may not be provided with a mixing chamber, and the fuel gas and the oxygen-containing gas may be independently introduced into the reaction furnace 11.

Fullerenes are produced by incomplete combustion of the fuel gas in the reactor 11. Examples of the fuel gas include gaseous or gasified aromatic hydrocarbons having 6 to 15 carbon atoms such as toluene, benzene, xylene, naphthalene, methylnaphthalene, anthracene, and phenanthrene, cleosorted oils, and carboxylic acid oils. Examples thereof include coal-based hydrocarbons, acetylene-based unsaturated hydrocarbons, ethylene-based hydrocarbons, and aliphatic saturated hydrocarbons such as pentane and hexane, and two or more of them may be used in combination. Among these, aromatic hydrocarbons are preferable. Further, the fuel gas may be diluted with an inert gas such as nitrogen gas or argon gas, if necessary. Examples of the oxygen-containing gas include oxygen gas and air. Further, the oxygen gas may be diluted with an inert gas such as nitrogen gas or argon gas.

The reaction furnace 11 is made of a heat-resistant material such as zirconia, molybdenum, tantalum, platinum, titanium, titanium nitride, and alumina, and at least one selected from carbon materials, silicon carbide, and vanadium dioxide on the entire or part of the inner peripheral surface. It has a coating layer 12 containing the material of. Examples of the carbon material include graphite, soot, carbon black, carbon nanotubes, fullerenes, carbon nanohorns, carbon fibers and the like. Examples of silicon carbide include black silicon carbide powder and silicon carbide fiber. Examples of vanadium dioxide include black vanadium dioxide powder. From the viewpoint of heat resistance, the coating layer 12 is preferably composed of at least one selected from graphite, carbon black, carbon fibers, and silicon carbide. The total content of the material in the coating layer 12 is preferably 50% by mass or more, and more preferably 90% by mass or more.

When producing fullerenes, the temperature inside the reactor 11 is usually estimated to be 1000 ° C. or higher. Normally, the emissivity of the refractory material constituting the reactor 11 is less than 0.40. Since the emissivity of each of the above materials used for the coating layer 12 exceeds 0.70, the coating layer 12 enhances the heat retaining effect of the reactor and can maintain the inside of the reactor 11 at a high temperature. Maintaining the inside of the reactor at a high temperature has the effect of improving the yield of fullerenes. Here, the emissivity is the ratio of the radiation intensity of the radiator (the above material) to the radiation intensity of the blackbody at the same temperature as the radiator. In the present invention, the emissivity is the average value of the emissivity in the wavelength range of 0.5 μm to 10.0 μm at 1000 ° C. The emissivity of the carbon material is 0.80 to 0.92, the emissivity of silicon carbide is 0.80 to 0.83, and the emissivity of vanadium dioxide is 0.70 to 0.82.

The coating layer 12 may be formed on the entire inner peripheral surface of the reactor 11, or may be formed on a part of the inner peripheral surface. That is, there may be a portion of the inner peripheral surface that is not covered with the covering layer 12, and there may be a portion where the inner peripheral surface is exposed. When the covering layer 12 is formed on a part of the inner peripheral surface, it is preferable that 50% or more of the total area of the inner peripheral surface is covered with the covering layer 12, and 70% or more is covered. Is more preferable. Further, the coating layer 12 is preferably formed on the inner peripheral surface above the reaction furnace 11, particularly on the inner peripheral surface near the burner 13. When the coating layer 12 is formed on a part of the inner peripheral surface of the reaction furnace 11, the coating layer 12 may be formed continuously or intermittently, and may be scattered. It may be formed.

The coating layer 12 may have a single-layer structure or a laminated structure. Further, the thickness of the coating layer 12 may be uniform or non-uniform. When the thickness of the coating layer 12 is uniform, the thickness is preferably 0.5 mm or more, and more preferably 1.0 mm or more. When the thickness of the coating layer 12 is non-uniform, the thickness of half or more of the total area of the coating layer 12 is preferably 0.5 mm or more, and more preferably 1.0 mm or more.

When the coating layer 12 has a layer containing a carbon material, it is preferable to have a layer containing at least one of silicon carbide and vanadium dioxide on the layer containing the carbon material. In this case, in the coating layer 12, a layer containing a carbon material and a layer containing at least one of silicon carbide and vanadium dioxide that coat the layer containing the carbon material are laminated in order from the inner peripheral surface side. Since fullerenes are usually produced by incomplete combustion of fuel gas, oxygen in the oxygen-containing gas is deficient with respect to the fuel gas. Therefore, since oxygen is consumed by reacting with the fuel gas in the burner 13, it is considered that the possibility that oxygen reacts with the carbon material of the coating layer is extremely low. However, in preparation for an emergency such as an abnormal reaction, it is preferable that the layer containing the carbon material is coated with a layer containing at least one of silicon carbide and vanadium dioxide which are difficult to react with oxygen at high temperatures as described above. The thickness of the layer containing at least one of silicon carbide and vanadium dioxide is preferably 0.05 μm to 0.1 mm.

As shown in FIG. 1, the lower part of the reactor 11 is connected to the pipe 19. Exhaust gas containing fullerene-containing soot-like substance, carbon monoxide gas, water vapor, etc. generated in the reaction furnace 11 passes through the pipe 19 and reaches the fullerene recovery device 16.

The fullerene recovery device 16 includes a filter 22 that separates the gas from the soot-like substance containing the fullerene in the exhaust gas. The filter 22 passes unreacted fuel gas, carbon monoxide, water vapor, and other gases in the exhaust gas to recover soot-like substances containing fullerenes. The filter 22 has a bag filter structure used in a normal dust collector or the like. Examples of commercially available filters 22 include sintered metal filters (manufactured by Nippon Pole) and sintered metal filters (manufactured by Fuji Filter).

The fullerene recovery device 16 is connected to the gas cooler 17 via a pipe 27. The gas cooler 17 has the same or similar structure as a normal heat exchanger, and by lowering the temperature of the gas and flowing it into the vacuum pump 18, the volume of the gas is reduced and the load of the vacuum pump 18 is reduced. Let me. Further, the gas cooler 17 liquefies the unreacted fuel gas and water vapor in the gas and discharges them from the drain 28 below the gas cooler 17.

The effects of the present invention will be made clearer by the examples and comparative examples. The present invention is not limited to the examples, and can be appropriately modified and implemented without changing the gist thereof.

(Calculation of fullerene yield)
The content of fullerene (FLN) contained in the soot-like material recovered by the fullerene recovery device 16 was measured as follows in accordance with JIS Z 8981. In each of the Examples and Comparative Examples, 15 g of 1,2,3,5-tetramethylbenzene (TMB) was added to 0.05 g of the recovered soot-like substance, and the mixture was sonicated for 15 minutes. The obtained suspension was filtered through a membrane filter having a pore size of 0.5 μm. The obtained extract is analyzed by high performance liquid chromatography (HPLC) to quantify the fullerenes (C60, C70) contained in the soot-like substance, and the fullerene content (the amount of fullerene (mass%) with respect to the obtained soot-like substance). ) Was calculated. For the quantification of fullerenes, a calibration curve was prepared in advance using a solution having a known fullerene concentration.
The measurement conditions for HPLC are as follows.
Equipment: Infinity 1260 (manufactured by Agilent)
Sample solution injection volume: 5 μL
Eluent flow rate: 47 volume ratio (vol%) Toluene / methanol 1 ml / min Column: YMC-Pack ODS-AM 100 * 4.6 mm ID S-3 μm, 12 nm
Measurement temperature: 40 ° C
Detector: UV 325nm (JIS)
The fullerene (FLN) yield was calculated from the obtained FLN content using the following formula.
FLN yield (%) = (recovery of soot (g) / fuel consumption (g)) x FLN content (%)

(Example 1)
(Preparation of coating layer)
Carbon fibers (average fiber diameter 13 μm, average fiber length 0.11 mm) were dispersed in an ethanol solvent, and a dispersion was prepared so as to obtain fluidity suitable for coating. A zirconia-made reactor 11 having an inner diameter of 10 cm and a length of 200 cm is rotated, a long nozzle for coating the inner surface is inserted into the reactor 11, and the dispersion liquid is applied to the entire inner peripheral surface of the reactor 11 by a spray method. It was applied. The amount of the dispersion liquid to be applied was adjusted so that the thickness of the coating layer 12 obtained in the firing step described later was 3.0 mm. The ethanol solvent is volatilized in the air, the reaction furnace 11 is heated to 1500 ° C. at a rate of 10 ° C./min in a nitrogen gas atmosphere, fired at 1500 ° C. for 2 hours, and then naturally cooled to room temperature. rice field. As a result, a coating layer 12 containing carbon fibers was formed on the entire inner peripheral surface of the reactor 11.

(Generation of fullerenes)
A fullerene was produced by the fullerene production apparatus 10 of FIG. 1 using the reactor 11 having the coating layer 12 obtained above. The yield of fullerene was calculated by measuring the content of fullerene in the produced soot-like substance.
At this time, gasified toluene was used as the fuel gas, and pure oxygen was used as the oxygen-containing gas. Toluene was once heated in a vaporizer to make it gaseous, and then heated to 200 ° C. in a heat exchanger. Oxygen gas was supplied from the oxygen tank to the heat exchanger and heated to 200 ° C. Then, the flow rate of toluene gas is set to 228.3 g / min and the flow rate of oxygen gas is set to 175.7 N liter / min to supply the burner 13, and the mixture is premixed in the mixing chamber to obtain a mixed gas and discharged into the reaction furnace 11. I let it ignite. The fullerene yield was calculated by the above-mentioned method for calculating the fullerene yield. The yield of fullerene was 1.40%.

(Example 2)
A coating layer was formed in a range of 100 cm from the position corresponding to the position of the surface portion (tip portion) of the burner 13 on the inner peripheral surface of the reactor 11 toward the downstream side (direction toward the pipe 19). Fullerenes were produced in the same manner as in Example 1. That is, 50% of the total area of the inner peripheral surface was covered with the coating layer 12. The yield of fullerene was 1.35%.
(Example 3)
In the same manner as in Example 1 except that the coating layer 12 was formed by using carbon fibers having a mass ratio of 40:60 and black silicon carbide powder (particle size range 0.1 μm to 100 μm) instead of the carbon fibers. Fullerene was produced. The yield of fullerene was 1.75%.
(Example 4)
The coating layer 12 was formed by using graphite fine powder having a particle size range of 0.1 μm to 100 μm instead of the carbon fibers of Example 1. Other than that, fullerenes were produced in the same manner as in Example 1. The yield of fullerene was 2.10%.
(Example 5)
Fullerenes were produced in the same manner as in Example 1 except that the coating layer 12 was formed by using black silicon carbide powder (particle size range 0.1 μm to 100 μm) instead of carbon fibers. The yield of fullerene was 2.00%.
(Example 6)
Fullerenes were produced in the same manner as in Example 1 except that the coating layer 12 was formed by using black vanadium dioxide powder (particle size range 0.5 μm to 100 μm) instead of carbon fibers. The yield of fullerene was 1.50%.
(Example 7)
The coating layer 12 was formed by using carbon black (manufactured by Mitsubishi Chemical Corporation, MCF # 900) instead of the carbon fibers of Example 1. Other than that, fullerenes were produced in the same manner as in Example 1. The yield of fullerene was 2.10%.
(Example 8)
The same as in Example 7 except that the coating layer 12 was formed in a range of 120 cm from the position corresponding to the position of the surface portion (tip portion) of the burner 13 on the inner peripheral surface of the reaction furnace 11 toward the downstream side. Generated fullerenes. That is, 60% of the total area of the inner peripheral surface was covered with the coating layer 12. The yield of fullerene was 1.60%.
(Example 9)
In the same manner as in Example 7 except that a coating layer was formed in a range of 150 cm from the portion corresponding to the position of the surface portion (tip portion) of the burner on the inner peripheral surface of the reaction furnace 11 toward the downstream side. Generated fullerenes. That is, 75% of the total area of the inner peripheral surface was covered with the coating layer 12. The yield of fullerene was 1.90%.
(Example 10)
After forming the carbon black coating layer 12 of Example 7, the silane gas was heated to 1000 ° C. in the reaction furnace 11 at a rate of 100 mL / min and maintained for 30 minutes. As a result, a silicon carbide layer was formed on the surface of the carbon black coating layer 12. The thickness of the silicon carbide layer was 0.05 μm. Other than that, fullerenes were produced in the same manner as in Example 7. The yield of fullerene was 2.05%.
(Comparative Example 1)
Fullerenes were produced in the same manner as in Example 1 except that the reactor 11 in which the coating layer 12 was not formed was used. The yield of fullerene was 0.70%.

It was confirmed that the yields of fullerenes of Examples 1 to 10 were improved as compared with Comparative Example 1. It was found that the fullerene yield can be improved by using the reaction furnace 11 having the coating layer 12.

10 Fullerene production equipment 11 Reaction furnace 12 Coating layer 13 Burner 14 Insulation 16 Fullerene recovery equipment 17 Gas cooler 18 Decompression equipment 19 Piping 22 Filter 27 Piping 28 Drain

Claims (4)

A reactor used to produce fullerenes by the combustion method.
A reactor having a coating layer containing at least one selected from a carbon material, silicon carbide and vanadium dioxide on the inner peripheral surface of the reactor. The reactor according to claim 1, wherein the area of the inner peripheral surface having the coating layer is 50% or more of the total area of the inner peripheral surface. The coating layer has a layer containing the carbon material, a layer containing at least one of the silicon carbide and vanadium dioxide for coating the layer containing the carbon material, in order from the inner peripheral surface side, claim 1. Or the reactor according to 2. A fullerene production apparatus having the reactor according to any one of claims 1 to 3.

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