JP2021038103A - Graphene and production apparatus of graphene - Google Patents

Abstract

To provide a production apparatus suited for mass production of a high purity carbon material in a short time by using a vegetable raw material as a carbon source, and the carbon material obtained by using the production apparatus.SOLUTION: A production method is characterized as including: a pretreatment step (S1) to obtain a carbon source by drying a vegetable raw material, drying and crushing; a carbonization step (S2) to obtain a carbide by carbonizing the carbon source; and an activation process (S3) to remove a contaminant including silicon from the carbide obtained in the carbonization step, and the carbonization step is characterized as including a heating step to supply an inert gas into a chamber and to heat the carbon source in the chamber in a plasma atmosphere. The obtained graphene is characterized as having minute irregularity of 1 μm or less including a silicon ingredient and a potassium ingredient.SELECTED DRAWING: Figure 1

Description

The present invention relates to graphene obtained by using a manufacturing apparatus for producing graphene, which is a large amount of carbon material, in a short time by using a plant raw material as a carbon source.

Conventional methods for producing nanocarbon include an arc discharge method, a laser evaporation method, a chemical vapor deposition method (CVD method), and the like. Among them, the method known for mass production is the super-growth method, which is a kind of chemical vapor deposition method (CVD method), in which single-walled carbon nanotubes are mass-produced.

For example, Patent Document 1 describes a thermal decomposition liquid recovery means for thermally decomposing an organic substance treatment material to recover a tar-mixed thermal decomposition liquid, and a thermal decomposition liquid for removing tar from the recovered tar-mixed thermal decomposition liquid. Examples thereof include the invention of a nanocarbon production apparatus having a means and a nanocarbon producing means for producing nanocarbon from a pyrolysis solution from which tar is removed, and producing nanocarbon from an organic substance treatment material.

For example, Patent Document 2 describes a rotating drum having a pyrolysis chamber and a nanocarbon generation chamber having a reducing atmosphere partitioned by a partition plate having a through hole in the center, and nanocarbon generation arranged in the nanocarbon generation chamber. A plate, an electric heater arranged on the outer periphery of the rotary drum, a raw material supply means for supplying biomass raw materials or waste to a pyrolysis chamber, and a scraping means for scraping nanocarbon generated on a nanocarbon generation plate. The biomass raw material or waste is thermally decomposed in the pyrolysis chamber, the pyrolysis gas containing hydrocarbons is sent to the nanocarbon generation chamber, and the nanocarbon production plate and the pyrolysis gas are reduced in this nanocarbon generation chamber. One example is the invention of a nanocarbon production apparatus characterized in that nanocarbons are generated and grown on a nanocarbon generation plate by contacting them in an atmosphere.

For example, Patent Document 3 describes a method for producing a sintered body containing carbon nanohorns, wherein a preformed body containing carbon nanohorns produced by arc discharge or corona discharge in a fluid is heated to a temperature of 1000 ° C. or higher. Examples thereof include the invention of a manufacturing method including a sintering step of pressurizing and sintering.

Japanese Unexamined Patent Publication No. 2009-242180 JP-A-2010-042935 International Publication WO2013 / 0538382

There is a method of producing graphene from a fossil-derived raw material as in Patent Document 3, but from the viewpoint of reducing carbon dioxide, Patent Documents 1 and 2 use a biomass material instead of a fossil-derived raw material. It is possible to obtain graphene.
Biomass materials are cheaper than graphite and hydrocarbon gas, and raw materials can be procured at low cost.

The present invention has been made to solve the above problems, and provides a manufacturing apparatus suitable for mass production of graphene, which is a material of nanocarbon, and uses this manufacturing apparatus to produce high-purity graphene and the like. To provide.

An induction heating device that supplies an inert gas and heats it by induction heating that generates a magnetic field by alternating current, the storage container formed of a conductor that can be heated by induction heating, and cooling the inside of the pipe by circulating water. It is characterized by being equipped with a heavy pipe cooling device.

Based on the above characteristics, the present invention can efficiently produce a large amount of graphene at low cost and in a short time, and can produce graphene with high purity.

It is a figure which shows the process flow which shows the manufacturing process of an embodiment. It is a schematic diagram which shows the structure of the plasma apparatus of embodiment. It is a schematic diagram which shows the structure of the plasma apparatus of another embodiment. It is a schematic diagram which shows the structure of the activation apparatus of embodiment. It is a schematic diagram which shows the structure of the carbonization furnace apparatus of embodiment. It is a figure which shows the relationship between the temperature of a carbon source and the theoretical yield of a carbide in the manufacturing process of an embodiment. It is a block diagram which shows the structure of the high frequency induction heating apparatus of embodiment. It is a schematic diagram which shows the structure of the high frequency induction heating apparatus of embodiment. It is sectional drawing which shows a part of the high frequency induction heating apparatus of embodiment. It is a schematic diagram which shows a part of the high frequency induction heating apparatus of embodiment. It is a schematic diagram which shows a part of the high frequency induction heating apparatus of embodiment. It is a schematic diagram which shows the structure of the plasma apparatus of another embodiment. It is a schematic diagram which shows a part of the other high frequency induction heating apparatus of an embodiment. It is a schematic diagram which shows a part of the other microwave induction heating apparatus of an embodiment. It is explanatory drawing explaining the state that the carbon source was carbonized by the induction heating apparatus of embodiment. It is a conceptual diagram which shows the structure of the carbide obtained by the manufacturing apparatus of this invention. It is a conceptual diagram which shows the structure of graphene obtained by the manufacturing apparatus of this invention. It is an XPS spectrum figure by narrow spectrum measurement of carbide and graphene obtained by the manufacturing apparatus of this invention. It is an XPS spectrum figure by narrow spectrum measurement of carbide and graphene obtained by the manufacturing apparatus of this invention. It is a distribution map of the pore diameter of carbide and graphene obtained by the manufacturing apparatus of this invention. It is a Raman spectrum of graphene obtained by the manufacturing apparatus of this invention. It is a Raman spectrum of a carbide obtained by the manufacturing apparatus of this invention. It is a Raman spectrum of graphene obtained from a conventional mineral. It is an electron micrograph of graphene obtained by the manufacturing apparatus of this invention. It is an elemental distribution map of graphene shown in FIG. It is an electron micrograph of the carbide obtained by the manufacturing apparatus of this invention. FIG. 6 is an elemental distribution diagram of carbides shown in FIG. It is a photograph which imaged the carbide obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph which imaged the carbide obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph which the carbide shown in FIG. 29 was transmitted through a scanning transmission electron microscope. It is a photograph which imaged the carbide obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph which the carbide shown in FIG. 31 was transmitted through a scanning transmission electron microscope. It is a photograph which imaged the graphene obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph showing the graphene shown in FIG. 33 transmitted through a scanning transmission electron microscope. It is an electron micrograph of the carbide obtained by the manufacturing apparatus of this invention. It is an electron micrograph of graphene produced from a mineral. It is an electron micrograph of graphene produced from a mineral. It is a figure which showed the relationship between the temperature distribution for producing graphene and the degree of graphitization. It is a Raman spectrum of graphene obtained by the manufacturing apparatus of this invention. It is a Raman spectrum of graphene obtained by the manufacturing apparatus of this invention. It is a photograph which imaged the graphene obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph showing the graphene shown in FIG. 41 transmitted through a scanning transmission electron microscope. It is a photograph which imaged the graphene obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph showing the graphene shown in FIG. 41 transmitted through a scanning transmission electron microscope. It is an electron micrograph of graphene obtained by the manufacturing apparatus of this invention. It is an electron micrograph of graphene obtained by the manufacturing apparatus of this invention. It is an electron micrograph of graphene obtained by the manufacturing apparatus of this invention. It is an electron micrograph of graphene obtained by the manufacturing apparatus of this invention. It is a photograph which imaged the graphene obtained by the manufacturing apparatus of this invention by a scanning transmission electron microscope. It is a photograph showing the graphene shown in FIG. 49 transmitted through a scanning transmission electron microscope. Graph of the relationship between time and temperature when forming carbides

The graphene manufacturing apparatus according to the present invention and the graphene produced by the graphene manufacturing apparatus will be described in detail with reference to the drawings. The embodiments and drawings described below exemplify a part of the embodiments of the present invention, are not used for the purpose of limiting to these configurations, and do not deviate from the gist of the present invention. Can be changed as appropriate in.

<Biomass material>
The vegetable raw materials for producing graphene will be described with reference to Examples 1 to 6. The present invention uses food residues and discarded vegetable ingredients to produce the final product, graphene. As the vegetable raw material, plants, wood, etc. are used, but if the discarded plant raw material such as the residue when the plant is harvested is used as the raw material for producing graphene, the raw material can be obtained at low cost. Is.

Table 1 is a composition table of vegetable raw materials. In Table 1, the ratios of the components constituting the raw materials shown on the far left are shown as percentages on the right below. For example, rice straw has 37.4% carbon (C), 0.53% nitrogen (N), 0.06% phosphorus (P _{), 0.14% phosphoric acid (P 2} O ₅ ), and so on. potassium (K) 1.75% potassium _(K 2 O) 2.11% calcium (Ca) 0.05% magnesium (Mg) 0.19% and sodium (Na) 0.11 It is%.

Here, the plant-derived silicon-containing porous vegetable raw material does not substantially change even when carbonized at a low temperature (300 ° C. or higher and 1000 ° C. or lower), and the pores are arranged by removing silicon. Can be maintained. Many plant-derived materials have a structure in which cells are regularly arranged along the axis and silicic acid is deposited on the cell wall to thicken the cells. Then, there is a compressed narrow cell row between the silicified cell rows, and it is possible to obtain a carbon material having a high specific surface area by removing silicon and the like after carbonization. As described above, those containing as much silicic acid as 13% or more and 35% or less are suitable. Even if the amount of silicic acid is too large, the amount of graphene obtained will be small, so a vegetable raw material in the range of about 20% is preferable.

Table 1 shows examples of vegetable raw materials that contain a large amount of carbon. In addition to rice straw, wheat straw, barley straw, rice bran, rice husks, buckwheat straw, soybean straw, corn vine, corn leaves, etc. There are carrot leaves, corn culms, sugar cane heads, coconut meal, peanut shells, mandarin husks, red cedar shavings, pine bark and ginkgo fallen leaves. In addition, the plant itself may be used instead of the residue.

For example, bamboo has fibers composed of cellulose, hemicellulose, and lignin, and minerals composed of iron, magnesium, calcium, manganese, copper, nickel, and the like. Further, when the bamboo leaves are fired, silanol groups (Si—OH) are extracted, and in the process of firing, they are extracted as SiO4.

Tables 2 and 3 are component composition tables of the vegetable raw materials most suitable for the method for producing the carbon material among the carbon sources 9 which are the plant raw materials in Table 1 described above in the present invention. Table 2 shows the ratio of the components constituting the raw material as a percentage. For example, water content is 8% to 10%, ash content is 10% to 18%, fat content is 0.1% to 0.5%, lignin is 18% to 25%, hemicellulose is 16% to 20%, and cellulose is 30%. ~ 35% and others are 5% -10%. As described above, the main components of silica ash 19 are lignin, hemicellulose, and cellulose.

Table 3 shows the inorganic chemical components of the carbon source 9 which is the vegetable raw material shown in Table 2. The carbon source 9, which is a vegetable raw material shown in Table 2, contains 80 wt% of organic substances such as cellulose and 20 wt% of inorganic substances. The inorganic chemical components in Table 3 are 92.14 _{wt% for SiO 2} , 0.04 wt% for _{Al 2} O ₃ , 0.48 wt% for Ca O, 0.03 wt% for _{Fe 2 O 3, and 3.2 wt% for K 2} O. %, MgO is 0.16 wt%, MnO is 0.18 wt%, and Na ₂ O is 0.09 wt%. The carbon source 9, which is a vegetable raw material shown in Table 2, contains a large amount of _{silicon oxide (SiO 2) as an inorganic substance.}

(Graphene and carbides)
The carbide 19 obtained in the carbonization step S2 produced in Examples 1 to 10 and the graphene 113 obtained in the activation step S3, which is a carbon material, are shown in FIGS. 16 to 34. FIG. 24 is an electron micrograph of graphene 113, which is a carbon material obtained in the activation step S3, at a magnification of 50,000. FIG. 26 is an electron micrograph of 100,000 times as much as the carbide 19 containing 24 wt% of silicon (Si) obtained in the carbonization step S2.

FIG. 28 is an electron micrograph of a carbon material containing 24 wt% of silicon (Si) obtained in the carbonization step S2 at a magnification of 30,000. FIG. 29 is an electron micrograph of 100,000 times as much as the carbide 19 obtained in the carbonization step S2. FIG. 35 is an electron micrograph of 2,200 times the carbide 19 obtained in the carbonization step S2.

FIG. 30 is a 100,000-fold image of the carbide 19 obtained by the manufacturing apparatus of the present invention, taken with a scanning transmission electron microscope shown in FIG. 29 and transmitted. FIG. 31 is an 80,000-fold image of the carbide 19 obtained by the manufacturing apparatus of the present invention taken with a scanning transmission electron microscope. FIG. 32 is an image of the carbide 19 obtained by the manufacturing apparatus of the present invention taken with a scanning transmission electron microscope shown in FIG. 31 and transmitted at a magnification of 80,000.

FIG. 33 is a 100,000 times image taken with a scanning transmission electron microscope of graphene 113 obtained by the manufacturing apparatus of the present invention. FIG. 34 is an image of graphene 113 obtained by the manufacturing apparatus of the present invention taken with a scanning transmission electron microscope shown in FIG. 33 and transmitted at a magnification of 100,000.

FIG. 36 is an electron micrograph of graphene C produced from minerals by a conventional method at a magnification of 10,000 times. FIG. 37 is an electron micrograph of graphene C produced from minerals by a conventional method at a magnification of 100,000.

In the carbide 19 obtained in the carbonization step S2 described later, the ash content excluding carbon is as large as 37.1 wt% according to thermogravimetric analysis, and silicon (Si) is 24 wt% of the total carbide 19 in the ash content. It is 30 wt% from. In addition, K is 0.51 wt% to 7 wt%, Al is 0.1 wt% to 1.6 wt%, Ca is 0.17 wt% to 0.5 wt%, Fe is 0.4 wt%, and Cr, Ni, Mn, Mg, P, S and Na are 0.1 wt% or less.

The carbide 19 obtained in the carbonization step S2 without performing the activation step S3, which is a so-called activation treatment, contains a large amount of silicon, and when carbonized in an inert gas, it is not strongly reduced and becomes SiO2-x. It is considered that it binds to an aromatic -OH group or the like in the form of -O-Si-O-R to form a lignin polysaccharide complex, which tends to form a C / SiOx.

Further, the graphene 113 obtained in the activation step S3, which will be described later, has a large ash content excluding carbon of 26.7 wt% according to thermogravimetric analysis, of which silicon (Si) is 14 wt to 19 wt of the entire graphene 113. It is%. In addition, K is 4.3 wt%, Al is 1.5 wt%, Ca is 1.3 wt%, Fe is 0.4 wt%, and P, Mn, Cl, S, Mg is 0.1 wt% or less. It has become.

As described above, the amount of silicon in graphene 113 and carbide 19 is as large as 14 wt% to 30 wt%.
Therefore, the carbide 19 obtained in the carbonization step S2 has an effect of improving the cycle capacity when used as the negative electrode material of the battery material.

As shown in Table 4 and FIG. 20, as a result of CO ₂ adsorption / desorption measurement, it was confirmed that the graphene 113 and the carbide 19 had fine pores having a pore diameter of mainly 0.8 nm to 2 nm.

Therefore, it is considered that metal ions and the like are easily adsorbed. Further, as shown in Table 4, the volume of the mesopores measured by the gas adsorption measurement and the water vapor adsorption measurement was 0.487 ml / g for graphene 113 and 0.259 ml / g for carbide 19. The micropore volume was 0.46 ml / g for graphene 113 and 0.27 ml / g for carbide 19.

Further, as shown in Table 4, the particles of graphene 113 or carbide 19 have a distribution diameter of 15 μm to 229 μm, and the median diameter indicated by the median of the integrated values of the distribution is about 110 μm.

In this way, a mesopore volume of 0.2 ml / g to 0.6 ml / g is formed. In particular, graphene 113 after the activation treatment for removing impurities described later shows a higher value, and it is considered that mesopores and micropores are grown by removing silicon.

Moreover, as measured by water vapor adsorption measurement method, as shown in Table 4, the specific surface area by BET equation, graphene 113 showed 1792m ² / g, the width is the width of 890m ² / g~2000m ² / g .. Carbides 19 shows a 726.4m ² / g, the width is the width of 890m ² / g~1500m ² / g. In each case, the specific surface area of graphene 113 after removing the silicon component (Si) is larger than that of graphene 113. Therefore, graphene 113 has a high adsorption effect. In addition, it is possible to store a large amount of electric charge in the battery material.

Further, as shown in FIG. 35, the carbide 19 is also provided with a hole 96 having a diameter of 2 μm to 10 μm, which is 1000 to 10000 times larger than the pore 97. As described above, not only the large pores but also the pores 97 having a pore diameter of 0.8 to 2 nm are provided and have a porous property. Further, as shown in FIGS. 28 to 32, not only the pores 97 but also irregularities of about 50 nm to 100 nm are formed on the surface. From Figure 28, as shown in FIG. 32, carbides 19, silicon dioxide (SiO2), potassium peroxide _{(K 2 O 2),} it is formed by aggregates 98 aggregated spherically consisting of potassium (K) and the like.

FIG. 27 shows the element distribution of the carbide 19 imaged in FIG. 26, and the elements of C, O, Al, Si, and K can be confirmed. Carbide 19, as shown in FIGS. 26 and 27, formed by the aggregates 98 of 1μm from 500nm consisting such as silicon dioxide square shape or a substantially spherical surface containing carbon (SiO ₂₎ or potassium oxide _(K 2 O) The unevenness is provided. As shown in FIG. 27, fine silicon dioxide and potassium oxide are formed in the carbide 19 as a whole. _{Since potassium oxide (K 2} O) contained in the carbon source 9 is decomposed into potassium peroxide and silicon at 390 ° C., the carbide 19 is _{a sphere composed of potassium peroxide (K 2} O ₂ ) and potassium (K). Aggregates 98 aggregated in potassium oxide are formed. Also,

FIG. 25 shows the element distribution of the carbide 19 imaged in FIG. 24, and the elements of C, O, Al, Si, and K can be confirmed. As shown in FIGS. 25, 27, 33, and 34, the porosity of graphene 113 and carbide 19 extending in the vertical and horizontal directions, which are large and small, is the porosity and unevenness formed during the growth process of the vegetable raw material. As shown in FIGS. 24, 33 and 34, it is formed at the time of removal of impurities other than carbon including silicon (or silicon dioxide) and carbonization of organic substances by the activation step S3 for removing impurities. There is also porosity.

As shown in FIGS. 25 and 27, carbides 19 and graphene 113, silicon dioxide (SiO ₂₎ or potassium oxide _(K 2 O) or the like is attached to the entire carbides in a microscopic state. Therefore, the specific surface area is increased by removing these impurities.

Further, irregularities and pores 97 are formed on the surface of graphene 113. In particular, the carbide 19, a state in which the elemental components of K (potassium) has contained becomes small on the surface or inside of the carbide 19 in the state of K (potassium) or potassium oxide (K 2 _O), K ( there is a state formed by aggregation in the surface or inside of the carbides 19 while potassium) or potassium oxide (K 2 _O).

Similarly, the carbide 19 contains Si (silicon), which is an element component, in _{the state of Si (silicon) or silicon dioxide (SiO 2} ) in a minute amount on the surface or inside of the carbide 19. In the state of (silicon) or silicon dioxide (SiO ₂ ), there is a state in which the carbide 19 is aggregated and formed on the surface or inside. Then, by subjecting the carbide 19 to the activation treatment, the purity of carbon is increased and at the same time, the specific surface area is improved.

As shown in Table 4, the true density measured by gas replacement density measuring device, graphene 113 2.56 g / cm ³ and carbide 19 was 2.27 g / cm ^3. The bulk density of graphene 113 was 0.21 to 0.29 g / cm ³ .
The powder resistance values measured by the double ring method and the four-terminal method were 1.27 × 10 ^{3 to 5 Ω · cm for carbide 19, and 3.8 × 10 − for} graphene 113 by removing silicon. ^It becomes 2 Ω · cm and the conductivity is improved. Further, the carbide 19 is easily dissolved in a substance that is easily adsorbed on silicon by leaving a large amount of silicon, and at the same time, the insulating performance is improved.
The water content of graphene 113 measured by the coulometric titration method was 0.565%.

FIG. 21 is a Raman spectrum of graphene 113 obtained by the manufacturing apparatus of the present invention. FIG. 22 is a Raman spectrum of carbide 19 obtained by the production apparatus of the present invention. FIG. 23 is a Raman spectrum of graphene obtained from conventional minerals. These figures are analyzed by a Raman spectroscope, and the obtained data are ^{Raman spectra having a wavelength (wave number (Raman shift (cm -1} ))) on the horizontal axis and an intensity on the vertical axis.

Further, as shown in Table 4, the peak value ID of the peak value IG and D bands G band of the peak wavelength due to Raman spectroscopy ^{(1590cm -1) (1350cm -1)} .
Graphene C is a sheet-like monatomic film in which carbon atoms are π-bonded by sp2 hybrid orbitals and arranged in a hexagonal shape on one plane. In FIGS. 23, 36 and 37, graphene C produced from minerals is a multi-layered and highly crystalline graphene. On the other hand, it can be confirmed that the carbides 19 and graphene 113 produced in the present invention shown in FIGS. 21 to 35 are non-crystalline.

Then, as shown in Table 4, the value obtained by dividing the IG by ID is 1.68 for graphene 113 and 1.37 for carbide 19, indicating that the crystallinity is high among the vegetable raw materials. In particular, the carbide 19 contains a large amount of silicon and has higher crystallinity than graphene 113, and even if this silicon is removed, graphene 113 remains highly crystalline. As described above, since the carbide 19 before removing the silicon has high crystallinity, the graphene 113 remains high even after removing the silicon.

The value obtained by dividing the IG of the carbide 19 or graphene 113 by ID is preferably 0.9 or more, and shows a value of about 0.9 to 2.0.
Graphene 113 can also leave an amount of silicon component of 10 wt% to 30 wt% by adjusting the activation step (S3) described later.

As shown in FIG. 18, the results of wide spectrum measurement of the types and peak intensities of the elements contained in carbide 19 and graphene 113 using MgKa rays as an X-ray source by X-ray electron spectroscopy (XPS) are shown. ing. There is a Ca, P or S peak near 750 eV, an O peak near 530 eV, a C peak near 280 eV, and a Si peak near 160 eV.

Further, FIG. 19 is a diagram of an XPS spectrum showing the peak of C. It has been confirmed that the peak of graphene 113 tends to be broad as a whole, and the structure is disturbed by the activation step S3 described later, and oxygen-containing functional groups such as -OH, -CHO, and -COOH are generated. Was confirmed. In electric double layer capacitors and the like, the capacitance tends to increase with respect to the amount of functional groups applied. Therefore, graphene 113 has an increased oxygen-containing functional group in the activation step S3, so that the capacitance is also a carbide. It tends to increase compared to 19.
In particular, as a result of Fourier transform infrared spectroscopic analysis by the transmission method, it has been confirmed that ^{carbide 19 and graphene 113 have a peak near 3402 to 3424 cm -1} and a peak near 1018 to 1094 cm ^-1. ..

(Example 1)
The plasma apparatus 10 of this embodiment will be described with reference to FIG. FIG. 2 is a schematic view showing the configuration of the plasma device 10 of this embodiment. The plasma device 10 is mainly composed of an inert gas 6, a control device 20, a chamber 1, and a vacuum pump 30.

The inert gas 6 contained in the gas cylinder mainly uses argon, but other examples include helium, neon, and nitrogen. The inert gas 6 can be filled into the chamber 1 from the introduction pipe 7 via the gas amount control device 21. The gas amount control device 21 can adjust the flow rate of the inert gas 6.

The chamber 1 is connected to the control valve 22, and the inside of the chamber 1 can be evacuated to a vacuum state by the vacuum pump 30. It is connected to the chamber 1 and the inert gas 6 is introduced into the chamber 1. A leak valve 23 that opens the vacuum state in the chamber 1 to atmospheric pressure is provided between the control valve 22 and the chamber 1. Further, a control valve 14 and a leak valve 15 for opening the vacuum state in the chamber 1 to atmospheric pressure are also provided between the outlet pipe 8 for introducing the air in the chamber 1 and the vacuum pump 30.

Further, the temperature control device 24 controls the high frequency power supply 4, and manages the temperature holding, the holding time, and the like in the chamber 1. In the plasma device 10 of this embodiment, an argon gas, which is an inert gas 6, is passed as a working gas under a low pressure close to a vacuum state, a high current is passed between the cathode 2 and the anode 3 between the electrodes, and an arc discharge is performed. It is a method of obtaining thermal plasma by means of. A carbon crucible 5 is installed between the cathode 2 and the anode 3, and the crucible 5 contains a carbon source 9 described later. The carbon source 9 is carbonized in about 10 to 30 minutes by heating in a temperature range of 300 ° C. to 1000 ° C. by thermal plasma generated by an arc discharge. In addition to the above-mentioned plasma device, there is a method of obtaining thermal plasma by a barrier discharge, a corona discharge, a pulse discharge, or a DC discharge type.

(Example 2)
The plasma apparatus 100 of the second embodiment will be described with reference to FIG. In FIG. 3, the parts showing the same configuration as the plasma device 10 are designated by the same reference numerals, and the parts having the same configuration will not be described. The plasma device 100 mainly includes an inert gas 6, a control device 20, a chamber 1, and a vacuum pump 30. Mainly different from the plasma device 100, as a method of obtaining a carbon material by high frequency induction heating, an inert gas 6 is passed so as not to oxidize, and a high frequency magnetic field of 3 to 4 MHz is applied from the high frequency power supply 32 to the high frequency coil 31. As a result, carbonization is performed by induction heating of high-frequency alternating current. The carbon source 9 is carbonized in about 10 to 30 minutes by heating in the temperature range of 300 ° C. to 1000 ° C. by induction heating.

(Example 3)
The plasma apparatus 100A of the third embodiment will be described with reference to FIG. In FIG. 12, the parts showing the same configuration as the plasma device 10 and the plasma device 100 are designated by the same reference numerals, and the parts having the same configuration will not be described.

The plasma device 100A is a thermal plasma using an inductively coupled plasma torch similar to that of the second embodiment. As a method of obtaining a carbon material by high-frequency induction heating, the plasma device 100A flows an inert gas 6 so as not to oxidize it, and applies a high-frequency magnetic field of 3 MHz from the high-frequency power source 32 to the high-frequency coil 31 to generate high-frequency alternating current. The point is that carbonization is performed by induction heating. The carbon source 9 is carbonized in about 10 to 30 minutes by heating in the temperature range of 500 ° C. to 800 ° C. by induction heating.

The moving rod 125 can move up and down. As shown in FIG. 12, the inert gas 6 in which argon gas and hydrogen gas are mixed or the inert gas 6 using nitrogen gas is heated to about 10,000 ° C. by induced heating and is several tens of m / s or less. The gas is ejected from the outlet pipe 8 by injecting at a flow velocity. Further, in addition to the outlet pipe 8, a quenching gas for quenching may be ejected from the vicinity of the outlet pipe 8 and then led out from the outlet pipe 8.

Further, since the internal temperature of the plasma device 100A is high, a water-cooled double tube 121 is adopted as the water-cooling device. The plasma device 100A supplies cold non-conductor water from the water supply pipe 123a, collects the high-temperature non-conductor water by the drain pipe 123b, and suppresses the internal temperature rise.

The method of obtaining the carbon material mainly by the plasma device 100 and the high frequency induction heating is the same, but the difference is that the ascending rod 125 is provided. As shown in FIG. 12, the torch shows a flame-type temperature distribution (Ta, Tb, Tc). For example, the region required for the carbonization step S2 described later from 500 ° C. to 800 ° C. indicates Tc, and when the moving rod 125 reaches the position of Pc, the carbonization step S2 can be performed at a temperature of 500 ° C. to 800 ° C.

Further, the region required from 800 ° C. to 1000 ° C. in the activation step S3, which will be described later, indicates Tb, and when the moving rod 125 reaches the position of Pb, the carbonization step S2 can be performed at a temperature of 800 ° C. to 1000 ° C. Further, the region requiring the carbonization step S2 or the activation step S3, such as when improving the graphitization degree of 1000 ° C. or higher or when decomposition of silicon dioxide is required, shows Tc, and the moving rod 125 reaches the position of Pc. Then, the carbonization step S2 or the activation step S3 can be performed at a temperature of 1000 ° C. or higher. As described above, since the temperature of the plasma device 100A can be adjusted by the position where the moving rod 125 is installed, one device can be used for various manufacturing processes.

Inert gases 6 and 217 heated by the thermal plasma in the plasma devices 10, 100 and 100A are flowing, and the plant raw material and the object to be carbonized are instantly evaporated and gasified. Nucleation and condensation of carbonized objects such as carbon source 9 and carbide 19 are carried out, and a chemical reaction in nanoparticles is carried out by a rapid quenching step. Therefore, it is excellent in mass production because it can be made into nanoparticles and a chemical reaction can be carried out in a short time.
By using the plasma devices 10, 100, and 100A as described above, even lignin or other impurities that are difficult to be thermally decomposed can be decomposed.

The plasma devices 10, 100, and 100A described above are high-frequency inductively coupled plasma torches, and the oxidizing atmosphere and the reducing atmosphere can be freely selected.
In the plasma devices 10, 100, and 100A described above, when an AC high-frequency high voltage is applied, filamentous plasma is randomly generated between the electrodes in time and space by passing through an insulator such as silicon. In addition, the electrons emitted from the electrodes by the corona discharge collide with the electrons and molecules in the chamber 1 and the vegetable raw material, so that excitation, dissociation, and ionization occur.

In such a high-energy space, a vapor phase reaction occurs, and in particular, by mixing a small amount of reactive gas with the inert gas 6,217, -OH (hydroxyl group), -CHO, -C = O Functional groups such as (carbonyl group) and -COOH (carboxyl group) are generated to impart hydrophilicity.

(Example 4)
In this embodiment, the high frequency induction heating device 200 for producing the above-mentioned carbide 19 and the like will be described with reference to FIGS. 7 to 11. The high-frequency induction heating device 200 is a device that generates a magnetic field and heats an object to be heated, which is a conductor, by induction heating of an alternating high frequency. The object to be heated is a storage box 205 made of carbon, which will be described later.

The high-frequency induction heating device 200 is a plurality of storage boxes 205 formed of carbon or a carbon composite material containing a carbon source 9 which is a vegetable raw material inside a transparent quartz tube 203 so that mass production is possible. Is provided. In this high-frequency induction heating device 200, when an alternating high-frequency current is passed through the coil 243, an alternating magnetic flux penetrates the conductor, a high-density eddy current flows, and the Joule heat rapidly heats the conductor.

Therefore, even if there is an insulator such as silicon dioxide (SiO ² ) in the carbon source 9, the magnetic flux is transmitted and the carbon source 9 is conducted, the carbon source 9 itself is heated, and the heating is accelerated and carbonized in a short time. can do. Further, since the insulator itself such as silicon dioxide (SiO ² ) penetrates the alternating magnetic flux, the silicon dioxide (SiO ² ) itself remains as it is because it is only heated from the storage box 205 and is not at the melting temperature. , Silicon dioxide (SiO ² ) and many other insulators remain.

First, the high frequency induction heating device 200 will be described with reference to FIGS. 7 and 8. A transparent cylindrical quartz tube 203 is provided between the left flange 231 and the right flange 232. The left and right flanges 231 and 232 can be sealed and opened so that the inside of the quartz tube 203 can be kept in a vacuum state or a low pressure state.

Further, the quartz tube 203 is removable from one of the left and right flanges 231 and 232 that is open. The left and right flanges 231 and 232 have a water-cooled cooling function.
The quartz tube 203 may be attached / detached and fixed so as to be sandwiched from both sides of the left and right flanges 231 and 232.

As shown in FIG. 8, the right flange 232 is connected to a pipe connected to a control valve 224 that controls the flow rate of the inert gas 217 and the combustion gas 218, and the inert gas 217 or the combustion gas 218 is connected to the quartz pipe 203. It is possible to fill the inside of. Further, the right flange 232 is connected to the low vacuum pressure gauge 219, and the left flange 231 is connected to the pressure control valve 222 and the control valve 224 via the filter 221.

Further, the control valve 224 can switch the inert gas 217 or the combustion gas 218 according to the temperature condition and the combustion time according to the process and flow into the quartz tube 203.
The control device 210 controls the pressure inside the quartz tube 203 by a dry pump 223 connected to the pressure control valve 222 and the control valve 224.

As shown in FIGS. 8 to 10, the high-frequency induction heating device 200 can create various temperatures through the quartz tube 203, and from the carbon source 9 which is a vegetable raw material, silica containing not only carbon but also silicon can be used. It is equipped with a high frequency coil 240 and an electric furnace 250 so that it can be used in the extraction and the activation process described above.

The high-frequency coil 240 is formed so as to surround the quartz tube 203, and a coil support 242 on which the coil 243 is supported is fixed to the drive device 1 (214). The drive device 1 (214) moves along the rail 236 in the X and −X directions. A motor is used in the drive device 1 (214). Instead of the motor, a linear drive or the like may be used.

The high-frequency coil 240 is different in that it can move in the X and −X directions, and once installed, it is possible to sequentially carbonize a plurality of storage boxes 205 accommodating the carbon source 9, so that many at once. It is possible to carbonize the carbon source 9 of. Mainly, in the manufacturing process, it can be utilized in the carbonization process of S2 in FIG. 1, which will be described later.
Further, the high frequency coil 240 is provided with a shielding plate 241 in the vicinity of the coil 243 in order to reduce the influence of electromagnetic waves emitted from the coil 243.

The high frequency induction heating device 200 is 300 ° C. or higher and 1000 ° C. or lower by high frequency induction heating as shown in FIG. 6 by flowing an inert gas 217 and applying a high frequency magnetic field of 20 KHz from the high frequency power supply 212 to the high frequency coil 240. A relatively large yield was obtained. The inert gas 217 has a role of flowing the inert gas 217 so that the gas generated from the direct material during carbonization does not stay in the quartz tube 203, and a role of collecting the generated gas and a role of preventing oxidation. doing.

The high-frequency induction heating device 200 as described above generates heat when lignin, which is difficult to thermally decompose by using the high-frequency coil 240 and the inert gas 217, is imparted with conductivity during carbonization. Therefore, it can be disassembled quickly. Further, unlike the combustion of gas or the like, the high-frequency induction heating device 200 is easy to control the temperature, does not generate toxic substances or the like, and is rapidly heated (from a temperature rise rate of 10 ° C./min). It can be adjusted up to about 100 ° C./min), and it can be uniformly carbonized by raising the temperature in a short time, so it is ideal for mass production in a short time.

The high-frequency power supply 212 is provided with a coil 243 and a water-cooled cooling device 213 for cooling the power supply. Further, a filter 221 made of non-woven fabric, cotton, paper or the like is provided so that the tar component or the like generated at the time of combustion in the quartz tube 203 does not affect the dry pump 223.

Further, in the temperature control device 211 shown in FIG. 7, a thermocouple 235 is provided close to each storage box 205 as shown in FIG. Therefore, the control device 210 can be carbonized at a desired temperature based on the information obtained from these temperature control devices 211. In particular, temperature control is important because the yield varies depending on the temperature. By controlling the temperature, the high-frequency induction heating device 200 can not only extract the carbide 19 from the vegetable raw material, but also extract silica containing silicon and the like.

The electric furnace 250 is formed so as to surround the quartz tube 203, and is fixed to the drive device 2 (216). The drive device 2 (216) moves along the rail 236 in the X and −X directions. A motor is used in the drive device 2 (216). Instead of the motor, a linear drive or the like may be used.

The temperature of the electric furnace 250 can be raised to nearly 1000 ° C. by the heat from a heating element provided, such as using Joule heat, and the inside of the quartz tube 203 is cleaned while supplying combustion gas 218. Is possible. Further, the electric furnace 250 can be burned when activating the carbide 19.
Further, the combustion gas 218 is used for supporting combustion, and the combustion gas 218 may be oxygen or the like. It is mainly used in the step of activation step S3 shown in FIG. 22, and is used when burning at around 1000 ° C.

The electric furnace 250 may be a low frequency induction furnace using an electromagnetic induction current, a high frequency induction furnace using an eddy current, an arc furnace using a solitary high heat, or the like. Further, the electric furnace 250 can supply oxygen, which is a combustion gas 218, and remove it as CO2 by burning it, and remove and clean the carbides attached to the originally transparent quartz tube 203. By doing so, it is possible to remove the carbonized combustion debris attached to the inner surface of the quartz tube 203 by the high-frequency coil 240 and make it easier for the magnetic field to pass through.

Next, the quartz tube 203 and the storage box 205 will be described with reference to FIGS. 9 to 11. As shown in FIGS. 10 and 11, the storage box 205 is formed of a carbon material in a box shape having an open upper end so as to store the carbon source 9 and the carbide 19. In particular, the high-frequency induction heating device 200 is provided with a plurality of storage boxes 205 so that a larger amount can be carbonized than the above-mentioned plasma devices 10 and 100.

Further, as shown in FIGS. 11B and 11C, the storage box 205 is provided with the same carbon lid 255 as the housing 257. The lid 255 is for preventing the carbon source 9 from scattering due to sudden boiling by gas or steam generated from the organic matter of the carbon source 9 at the time of carbonization. The lid 255 is provided with degassing holes 256 at four corners in order to allow gas, water vapor, and the like to escape.

The storage box 205 may be further provided with a stainless steel net 258 below the lid 255. The net 258 may be provided so as to cover the periphery of the carbon source 9, or may be provided so as to cover only above the carbon source 9. The net 258 also has the effect of suppressing scattering, allowing gas to pass through, and facilitating heat transfer due to induction heating from above.

As shown in FIG. 11A, when a plurality of storage boxes 205 are provided in the vicinity and heated in order from the direction in which the inert gas 217 flows, the heated inert gas 217 is stored in the adjacent storage box 205. The carbon source 9 is warmed, and the carbon source 9 is pre-dried. Therefore, the carbonization time of the second and subsequent storage boxes 205 can be shorter than that of the first storage box 205. In addition, the gas generated from the carbon source 9 does not cause sudden boiling.

The storage box 205 is fixed to a mounting table 206 provided with an upper end piece 208 having rod-shaped pieces protruding from four corners on the front surface and a plurality of piece-shaped lower end pieces 207 protruding upward from both ends on the back surface. The storage box 205 is provided with a hole into which a piece of the upper end piece 208 can be inserted at the same position as the lower upper end piece 208, and the upper end piece 208 is fitted into the hole. It is fixed to the mounting table 206.

The mounting base 206 to which the storage box 205 is fixed is mounted on the base 202 by fitting the lower end piece 207 along the base groove 204 which is a groove provided in the base 202. A plurality of base grooves 204 are provided so as to be displaced by Y1 in the width direction so that the storage boxes 205 can be installed in a staggered manner. Further, the storage boxes 205 are provided not only in the width direction but also in the X direction with a predetermined interval X1 as shown in FIG.

By separating the storage boxes 205 in the Y1 direction or the X direction as shown in FIGS. 9 and 10, the storage boxes 205 other than the target to be carbonized are prevented from being affected as much as possible during carbonization by heating. There is. Further, in order to enable temperature control, the base 202 secures a thermocouple storage space 209 which is a space in which the thermocouple can be fixed in the vicinity of the base groove 204.

As shown in FIG. 10, the quartz tube 203 is provided in a circular tubular shape having an outer diameter of about 125 mm, which is made of transparent quartz. Further, the mounting table 206 is formed to have a width in which the storage box 205 can be installed below the center of the inside of the quartz tube 203.

Although the high-frequency induction heating device 200 is configured to obtain carbon, it is also possible to extract silica containing silicon from a biomass material depending on temperature conditions, and in particular, it is also possible to produce non-crystalline silica. .. Further, not only the carbonization step S2 described above but also the activation step S3 can be performed by the electric furnace 250. Therefore, it is possible to perform various processes while controlling the temperature with the same device. Since the high frequency induction heating device 200 can freely change the temperature velocity gradient and the temperature by changing the output of the high frequency, it can correspond to various raw materials.

In the above-mentioned high-frequency induction heating device 200, the high-frequency coil 240 or the electric furnace 250, which is a part for applying heat, moves to give heat to the carbon source 9 housed in the storage box 205. , It is possible to easily create a space where pressure control is possible. Further, in the conveyor type, there is a concern about a chemical reaction with the oil required for the conveyor or the like, which may cause impurities to be mixed. Further, as compared with the conveyor type, the high frequency induction heating device 200 does not have to be costly because the device such as the mixing of the inert gas becomes complicated. Since the high-frequency induction heating device 200 is provided outside the quartz tube 203, inspection and maintenance work from the outside is easy.

It is also possible to use one device for the carbonization step S2 or the activation step S3, which will be described later. Further, the high frequency induction heating device 200 can also produce other substances by changing the temperature conditions. As described above, since the high frequency induction heating device 200 is a multifunctional device, it can be applied not only to production efficiency but also to various purposes.

The high-frequency induction heating device 200 may be a compact high-frequency induction heating device 200 in which the mounting table 206 is one and the length of the quartz tube 203 is also one. As a result, the carbonization step S2 is completed in 10 minutes per unit, so mass production is possible by increasing the number of units.

(Example 5)
The high frequency induction heating device 200A of Example 5 will be described with reference to FIG. In FIG. 13, the parts showing the same configuration as the high-frequency induction heating device 200 of the fourth embodiment are designated by the same reference numerals, and the parts having the same configuration will not be described.

In the high frequency induction heating device 200A, a water-cooled double pipe 263 is adopted as a water-cooling device so that heating of 3000 ° C. or higher is possible. The high-frequency induction heating device 200A supplies cold non-conductive water from the water supply pipe 262a, collects the high-temperature non-conductive water by the drain pipe 262b, and suppresses the internal temperature rise. Further, the inert gas 17a is an exhaust gas 217b or the like containing a gas generated during carbonization of an organic substance discharged from a lid 267 having a hole above the carbon source 9 placed in a carbon storage pot 265. A discharge pipe is provided to collect the gas.

(Example 6)
The microwave induction heating device 200B of Example 6 will be described with reference to FIG. The microwave induction heating device 200B is provided with a microwave generator 272 that irradiates an electromagnetic wave 273 having a frequency of 300 MHz to 300 GHz, and stores the carbon source 9 in a ceramic storage box 274 in a housing that shields microwaves. The microwave induction heating device 200B heats the water and the derivative contained in the carbon source 9 by induction heating in which the water and the derivative are vibrated by the microwave.

In particular, as shown in FIGS. 15A to 15D, the microwave induction heating device 200B generates heat when the carbon source 9 containing water 26 such as H2O becomes carbonized matter 19. It has good thermal efficiency, and organic substances containing water gradually become smaller and carbonize. Further, since the raw material having physical characteristics is a backbone that carries air holes and water, the carbon source 9 containing a large amount of water is particularly suitable for heating / decomposition by the microwave induction heating device 200B.

The effect of the high-frequency induction heating devices 200, 200A, and 200B is that the heat efficiency is good and the heating rate is high because the self or the derivative or the conductor generates heat. Further, the temperature control of the high frequency induction heating device 200 and 200A200B is easy. Further, by removing impurities such as silicon or silicon dioxide of the insulator, it is possible to form irregularities on the surface of the carbide 19 and graphene 113, and to form pores 97 as shown in FIG. 15 (D). Is.

(Example 7)
<Activator>
FIG. 4 is an example of an activator 40 that removes impurities such as silicon oxide from the carbide 19 in which the carbon source 9 is carbonized by the above-mentioned plasma devices 10 and 100.
The heating furnace 41 can heat the furnace 42 to nearly 2000 ° C. The large crucible 50 has a lid 51, and a small crucible 60 and activated carbon 53 are contained inside the jar 52. The small crucible 60 is provided with a lid 61 in which potassium hydroxide (KOH) 18 is mixed above the carbide 19 in the jar 62. For the small crucible 60 and the large crucible 50, a stable fine ceramic material or the like can be considered, and aluminum oxide Al2O3 or the like is used.

(Example 8)
The same configuration and the same configuration as in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. As described in Example 1 in FIG. 5, the carbon source 9 and the oxidation inhibitor 70 produced from the vegetable raw material in the pretreatment step S1 are placed in the kettle 83. Here, it is preferable that the carbon source 9 has a capacity of about 1/10 to 2/3 of the capacity of the kettle 83. In the pretreatment step S1, the granulator may not be used and only pulverization may be performed with a mill or the like.

Here, the oxidation inhibitor 70 may be a substance that is burned while suppressing the oxygen concentration in order to prevent oxidation during combustion, and may be a gas of a halide (carbon dioxide, nitrogen, halon 2402, halon 1121, halon 1301) or the like. A liquid may be mixed and burned.
After that, the atmosphere in the furnace 81 of the combustion furnace 80 is set to 800 ° C. or higher, and the carbon source 9 is burned at 20 atm, 400 ° C. or higher, and 900 ° C. or lower for 3 hours.

(Example 9)
<Process flow 1>
With reference to FIG. 1, a manufacturing process will be described for a method of manufacturing graphene, focusing on the above-mentioned Example 2. FIG. 1 is a diagram showing a process flow showing a manufacturing process of the embodiment.
First, in the pretreatment step S1, after drying the vegetable raw material as described above, the vegetable raw material is crushed, and the crushed vegetable raw material and a granulating agent such as PVA are mixed with water at a ratio of 10: 1. The vegetable raw materials are mixed and kneaded to an appropriate size, and heated to about 100 ° C. on a drying device such as a hot plate to evaporate the water content to generate a carbon source 9. Here, examples of the crushing method include a mill, a mixer, and a grinder. In particular, the granulating agent can prevent bumping due to the steam of the carbon source 9 during induction heating.

Next, the carbonization step S2 will be described. In the pretreatment step S1, about 0.8 g of the carbon source 9 is put into the crucible 5 and covered with a metal net or the like. The crucible 5 is arranged at a predetermined heating position of the above-mentioned plasma devices 10, 100, 100A. The pressure in the chamber 1 is reduced to 80 Pa by the vacuum pump 30, the inert gas 6 is injected into the chamber 1 at a flow rate of 8 to 10 ml / min, and the pressure in the chamber 1 is maintained at 1300 to 1500 Pa. There is. In the carbonization step S2, the same graphene can be produced by using Examples 1 and 3.

As shown in FIG. 6, the applicant performed the carbonization step S2 in 100 ° C. increments between the temperatures of 200 ° C. and 1100 ° C. by thermal plasma, and determined the temperature and yield when carbonizing the carbon source 9. The value obtained by dividing the weight of graphene 113, which is the final product obtained from 0.8 g of carbon source 9, is shown in FIG.

The highest yield of 36% was measured at 500 ° C. to 800 ° C., and a relatively large yield was obtained at 300 ° C. or higher and 1000 ° C. or lower. In this measurement, rice straw, bran, coconut husks, rice husks, peanut husks, etc. were used, and similar results were obtained. In the carbonization step S2, the carbon source 9 is carbonized in about 10 to 30 minutes by heating in the temperature range of 300 ° C. to 1000 ° C. by thermal plasma by arc discharge while flowing in the inert gas 6.

Next, the activation step S3 will be described. The carbide 19 obtained above is mixed with potassium hydroxide (KOH) 18 at a ratio of 5 to 1 and placed in the jar 62 of the small crucible 60 shown in FIG. 4 to cover the lid 61. The small crucible 60 is housed in the large crucible 50, and activated carbon 53 is embedded around the crucible 60. Activated carbon 53 is buried in the small crucible 60 to prevent oxygen from entering the crucible 60. In the heating furnace 41, the furnace 42 was heated to a temperature close to 950 ° C. and fired for about 2 to 3 hours.

Here, potassium hydroxide 18 is used from the viewpoint of improving the yield of graphene 113, which is the final product, in order to promote the removal of silicon. Examples of the base include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide, alkali metal oxides such as sodium oxide and potassium oxide, and magnesium oxide. , Alkaline earth metal oxides such as calcium oxide, alkali metal sulfides such as sodium sulfide and potassium sulfide, and alkaline earth metal sulfides such as magnesium sulfide and calcium sulfide. In addition, the lignin that has not been completely carbonized may be removed by an acid with one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, PTSA, and aluminum chloride.

Of the charcoal 19 reacted with potassium hydroxide, silicate reacts with potassium hydroxide 18 to become potassium silicate, and the remaining water-soluble potassium hydroxide (KOH) 18 (Fig. 4) and potassium silicate are used. The silicon oxide (silicon) is removed by dissolving it in water, setting the mixed solution on a filter paper, and passing it through a vacuum or depressurized filter. Then, in the dried activation step S3, it was possible to produce graphene 113, which is a final product having a weight of about 1/8 to 1/10 as compared with the case where the first vegetable raw material was granulated.

(Example 10)
<Process flow 2>
With reference to FIG. 1, a manufacturing process will be described for a method of manufacturing graphene using the high-frequency induction heating devices 200, 200A, and 200B of Example 5. Since the pretreatment step S1 in the process flow 1 of the above-mentioned Example 4 is the same, it is omitted.

The carbonization step S2 when the high frequency induction heating device 200 shown in FIGS. 7 to 11 of this embodiment is used will be described. In the pretreatment step S1, the carbon source 9 is spread in the storage box 205 and covered with a metal net such as stainless steel. A plurality of storage boxes 205 are staggered and arranged at predetermined heating positions of the high-frequency induction heating device 200 described above. The pressure in the quartz tube 203 is reduced to 80 Pa by the dry pump 223, the inert gas 217 is injected into the quartz tube 203 at a flow rate of 8 to 10 ml / min, and the pressure in the quartz tube 203 is 1300 to 1500 Pa. It is kept.

As shown in FIG. 6, the applicant performed the carbonization step S2 in 100 ° C. increments between the temperatures of 200 ° C. and 1100 ° C. by heating, and determined the temperature and yield when carbonizing the carbon source 9. The value obtained by dividing the weight of the carbide 19 obtained from 0.8 g of the carbon source 9 is shown in FIG. The highest yield of 36% was measured at 500 ° C. to 800 ° C., and a relatively large yield was obtained at 300 ° C. or higher and 1000 ° C. or lower.

In this measurement, rice straw, bran, coconut husks, rice husks, peanut husks, etc. were used, and similar results were obtained. In the carbonization step S2, the carbon source 9 is carbonized in a temperature range of 300 ° C. to 1000 ° C. in about 10 to 30 minutes by high-frequency induction heating while flowing in the inert gas 217.

Next, the activation step S3 will be described. The carbide 19 obtained above is mixed with potassium hydroxide (KOH) 18 at a ratio of 5 to 1 and placed in the jar 62 of the small crucible 60 shown in FIG. 4 to cover the lid 61. Further, the small crucible 60 is housed in the storage box 205 shown in FIG. 11, and activated carbon 53 is embedded around the crucible 60. Activated carbon 53 is buried in the small crucible 60 to prevent oxygen from entering the crucible 60. In the electric furnace 250, the inside of the quartz tube 203 was heated to a high temperature of about 950 ° C. and fired for about 2 to 3 hours.

Here, potassium hydroxide 18 is used from the viewpoint of improving the yield of graphene 113 in order to promote the removal of silicon. Examples of the base include alkali metal hydroxides such as sodium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide, alkali metal oxides such as sodium oxide and potassium oxide, and magnesium oxide. , Alkaline earth metal oxides such as calcium oxide, alkali metal sulfides such as sodium sulfide and potassium sulfide, and alkaline earth metal sulfides such as magnesium sulfide and calcium sulfide. In addition, the lignin that has not been completely carbonized may be removed by an acid with one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, PTSA, and aluminum chloride.

Of the charcoal 19 reacted with potassium hydroxide, silicate reacts with potassium hydroxide 18 to become potassium silicate, and the remaining water-soluble potassium hydroxide (KOH) 18 (Fig. 4) and potassium silicate are used. The silicon oxide (silicon) is removed by dissolving it in water, setting the mixed solution on a filter paper, and passing it through a vacuum or depressurized filter. Then, in the dried activation step S3, it was possible to produce graphene 113, which is a final product having a weight of about 1/8 to 1/10 as compared with the case where the first vegetable raw material was granulated.

(Example 11)
By further performing the following treatments in the pretreatment step (S1) of the above-described embodiment, it becomes easy to reduce the work steps of removing silicon, and graphene 113, which is a final product having high carbon purity, is produced. be able to. By removing silicon in advance, it is less likely that the inside of the furnace or chamber will be polluted by the combustion of silicon.

As a pretreatment step (S1), it is possible to pulverize the carbon source 9 which is a vegetable raw material, or use an inorganic acid before pulverizing to reduce or remove the silicon of the carbon source 9. By performing such a pretreatment step (S1), it is possible to omit the activation step (S3), and in particular, a carbonization step (S2) at around 3000 ° C. for increasing the degree of graphitization as in Example 7 is performed. By doing so, it is possible to produce high-purity, highly crystalline graphene 113 having 98% or more carbon and no metal as an impurity.

Inorganic acids include hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid and hydrofluoric acid, of which _{water (H 2} O _{) is reacted by reaction with silicon dioxide (SiO 2} ) and hydrofluoric acid (6HF). ) And silicon tetrafluoride (SiF ₄ ), and silicon can be removed.

(Example 12)
By using the above-mentioned carbonization apparatus (10, 100, 100A, 200, 200A, 200B) and changing the temperature condition to 1000 ° C. or higher, it is possible to produce high-quality graphene 114. Further, from 300 ° C. to around 900 ° C. of A, the pretreatment step (S1) is not performed in the low temperature region 71, and after the carbide 19 containing a large amount of silicon (Si) is produced (carbide step S2), argon gas or the like is used. Silicon carbide (SiC) is formed when B is heated at a temperature near 1700 ° C. to 2500 ° C. in the atmosphere of the inert gases 6 and 217.

(Example 13)
A method for producing graphene P of another embodiment will be described with reference to FIGS. 1 and 38. In this production method, graphene P having an improved degree of graphitization can also be produced by using the production apparatus (10, 100, 200) described above and changing the temperature conditions. In particular, since the high-frequency induction heating device 200A of Example 5 is a device capable of carbonizing at a high temperature of 3000 ° C. or higher, Example 5 will be described as an example.

Graphene P has two routes for manufacturing, and the route 1 will be described first with reference to FIG. Route 1 performs the pretreatment step S1 described above, and carbonizes the carbonization step S2 in the temperature range A of 300 ° C. to 900 ° C. of the temperature 71 described above. Next, the activation step S3 described above is performed to prepare graphene 113. Next, graphene 113 is prepared by performing a second carbonization step S4 in a temperature range D of 900 ° C. to 1300 ° C. at a temperature of 74 to prepare graphene 114.

Next, the graphene 114 is subjected to the above-mentioned HF treatment (S5), and the third carbonization step S6 is carried out in the temperature range C of 2500 ° C. to 3200 ° C. of the temperature 73, whereby the degree of graphitization is increased and compared with minerals. As a result, highly pure graphene P with few metallic impurities is produced.

Further, not only this step but also the step of Route 2 enables the production of graphene P having high purity. In Route 2, after producing graphene 1113, HF treatment (S5) is performed, and the third carbonization step S6 is performed in the temperature range C of 2500 ° C. to 3200 ° C. of the temperature 73, whereby the degree of graphitization is increased. High-purity graphene P with less metallic impurities than minerals is produced.

Further, the high temperature 73 of C from 2500 ° C. to around 3500 ° C. is temperature control in the case of graphitization, and graphene P having excellent graphitization degree and further excellent electrical conductivity is formed. In particular, the temperature around 2800 ° C to 3000 ° C is the best.

As shown in FIG. 38, in an atmosphere filled with an inert gas such as nitrogen or argon, silicon dioxide does not melt in the temperature range D of 900 ° C. to 1450 ° C. or lower shown in the temperature 74, but the acid. It is a good temperature range for increasing the purity of carbon by treatment or alkali treatment. Further, the temperature zone B or the temperature zone C is a temperature zone in which the numerical value of the specific surface area can be increased by removing the silicon dioxide because the silicon dioxide melts at 1650 ° C. or higher.

(Graphene 2)
As shown in FIGS. 39 to 50, graphene P having an improved degree of graphitization produced by the present embodiment will be described. FIG. 39 is a Raman spectrum of graphene 114 obtained by the manufacturing apparatus of the present invention. FIG. 40 is a Raman spectrum of graphene P obtained by the manufacturing apparatus of the present invention.

FIG. 41 is an electron micrograph of graphene 114 obtained by the manufacturing apparatus of the present invention at a magnification of 15,000. FIG. 42 is a 15,000-fold image of graphene 114 obtained by the manufacturing apparatus of the present invention taken by a scanning transmission electron microscope shown in FIG. 41 and transmitted.
FIG. 43 is an electron micrograph of graphene 114 obtained by the manufacturing apparatus of the present invention at a magnification of 200,000. FIG. 44 is an image of graphene 114 obtained by the manufacturing apparatus of the present invention taken by a scanning transmission electron microscope shown in FIG. 43 and transmitted at a magnification of 200,000.

FIG. 45 is an electron micrograph of graphene P obtained by the manufacturing apparatus of the present invention at a magnification of 1,000 times. FIG. 46 is an electron micrograph of graphene P obtained by the manufacturing apparatus of the present invention at a magnification of 5,000. FIG. 47 is an electron micrograph of graphene P obtained by the manufacturing apparatus of the present invention at a magnification of 10,000 times. FIG. 48 is an electron micrograph of graphene P obtained by the manufacturing apparatus of the present invention at a magnification of 100,000. FIG. 49 is an electron micrograph of graphene P obtained by the manufacturing apparatus of the present invention at a magnification of 40,000. FIG. 50 is a 40,000-fold image of graphene P obtained by the manufacturing apparatus of the present invention taken by a scanning transmission electron microscope shown in FIG. 49 and transmitted.

As shown in FIGS. 45 to 50, graphene P is also provided with holes 96 having a diameter of 2 μm to 10 μm, which are 1000 to 10000 times larger than the pores 97. As described above, not only the large pores but also the pores 97 having a pore diameter of 0.8 to 2 nm are provided and have a porous property. As shown in FIGS. 16 and 17, these large and small porosities extending in the vertical and horizontal directions include porosities formed during the growth process of the vegetable raw material, and removal of silicon 91 in the vicinity of the cell wall. There are also porosities formed during carbonization of organic matter. In FIGS. 42 and 44, spherical silicon dioxide 91 having a silicon component of about 15 nm to 50 nm is formed as minute irregularities.

The element number concentration of graphene P is 0.12 wt% with a small amount of metal components in impurities and a small amount of Al, and other oxygen (O) is 0.9 wt% to 1.24 wt%, and carbon is 98.6 wt%. %, And carbon has a purity of about 98%. Since the metal component is less than 1 wt% as described above, the purity of carbon is high.

FIG. 40 shows the peak of the wavelength of graphene P measured by the Raman spectrophotometer by the Raman spectral method, and shows that the crystallinity is high. The peak value ID of the peak value IG and D bands G band of the peak wavelength due to Raman spectroscopy ^{(1590cm -1) (1350cm -1)} .

Then, as shown in Table 5 and FIG. 40, the value obtained by dividing the IG by ID is about 8.67, which is a very high value in graphene P, indicating that the crystallinity is high.

FIG. 39 shows the wavelength peak of graphene 114 measured by the Raman spectroscopy method measured using a laser Raman spectrophotometer. As shown in FIG. 39 and Table 5, graphene 114 has an IG divided by ID of 0.91, carbon (C) of 79.82 wt%, silicon (Si) of 15.5 wt%, and potassium (K). ) Is composed of 2.13 wt%. This forms an excellent carbon material.

Further, the specific surface area measured by the water vapor adsorption measurement method and the BET method is 1780 m ² / g for graphene 114. The water content of graphene P measured by the coulometric titration method is 0.01%, preferably less than 1%.

The powder resistance value measured by the above-mentioned measuring method is 3.8 × 10 ^{-3 Ω · cm for graphene 114, and 1.6 × 10 -3} Ω · cm for graphene P by removing silicon. And the conductivity is improved.

(Relationship between carbonization temperature and time)
Table 5 and FIG. 38 show the relationship with the time during the carbonization step (S2) shown in FIG. 1 using the graphene production apparatus (10, 100, 100A, 200, 200A, 200B) described above. FIG. 38 is a diagram showing the relationship between the heating temperature and time during carbonization.

The case where the carbon source 9 is carbonized at a temperature of 500 ° C. by the high frequency induction heating device 200 will be described as an example. The heated surface area S shown in Table 5 indicates the inner surface area (cm ² ) including the lid 255 of the storage box 205. The heating volume V (cm ³ ) indicates the volume of the carbon source 9 stored in the storage box 205. ^{It represents the area to be heated per 1 cm 3 of the} carbon source 9, and it is considered that if the value of the heating area H is large, the area to be heated becomes large and the amount of heat increases.

In FIG. 38, the calorific value area ht is the time h (h) and the heating temperature when the temperature is raised from room temperature at a heating rate of 100 ° C./min and held at 500 ° C. for 25 minutes to carbonize the carbon source 9. It is a value expressed by the area indicated by the diagonal line. The heating coefficient K is a numerical value expressed by the product of the heating area H and the calorific value area ht. The heating coefficient K is preferably in the range of 130 to 280, and in particular, the holding temperature is 500 ° C. or higher in consideration of the yield, and the heating coefficient K is most preferably 150 to 260.
Although the high frequency induction heating device 200 is shown as an example, a graphene manufacturing device (10, 100, 100A, 200A, 200B) may be used. Further, the time from when heating is stopped (point D) to cooling (time between DE and E) may be calculated in addition to the calorific value area ht. Further, the heating coefficient K is preferably in the range of 130 to 300, and in particular, the holding temperature is 500 ° C. or higher in consideration of the yield, and the heating coefficient K is most preferably 150 to 280.

Another technical feature considered from the above embodiment is a manufacturing method for producing a carbon material (carbide 19), in which a heating surface area (S) indicating an area when heated by a storage portion is used as a carbon source (9). The value divided by the heating volume (V) indicating the volume when heating is defined as the heating area (H), and the relationship between the time (h) for heating the carbonization source and the temperature for heating the carbonization source is the area. The value represented by is represented by the calorific value area (ht), the product of the heating area (H) and the calorific value area (ht) is represented by the heating coefficient (K), and the value of the heating coefficient (K) is a value of 130 to 280. A method for producing a carbon material, which comprises heating the carbon source to produce the carbon material within the range indicated by.

According to the above method, it is possible to produce a carbon material in a short time with a good yield, and it is possible to produce graphene having a large specific surface area and a small amount of metal residue as a precursor for producing graphene. It is possible. In particular, in devices such as plasma devices and carbonization devices that use high-frequency induction heating, it is possible to produce a large amount of carbon material in a short time as long as the heating coefficient (K) is in the range of 130 to 280. Is.

Regarding the industrial use of graphene, which is the carbon material of the present invention, battery materials, semiconductors, heat dissipation materials, transparent conductive films, flexible thin films, filters, lightweight and high-strength composite members (including rubber, etc.), toners, ink materials, etc. It can be used for.

1 Chamber 2 cathode 3 anode 4, 32 high frequency power supply 5 crucible 6, 217 inert gas 7 introduction tube 8 outlet tube 9 carbon source 10, 100, 100A plasma device 14, 22, 224 control valve 15, 23 leak valve 19 carbide 20 Control device 21 Gas amount control device 30 Vacuum pump 31, 240 High frequency coil 40 Activator 41 Heating furnace 42, 81 Furnace 50 Large crucible 51, 61 Lid 52, 62 Pot 53 Activated charcoal 60 Small crucible 70 Oxidation inhibitor 71 Low temperature region 72 Medium temperature Region 73 High temperature region 80 Combustion furnace 83 Pot 96 Hole 97 Pore 98 Silicon 113, 114, P Graphene 200, 200A High frequency induction heating device 200B Microwave induction heating device 202 Base 203 Quartz tube 204 Base groove 205 Storage box 206 Mounting base 207 Lower end piece 208 Upper end piece 209 Storage space 210 Control device 211 Temperature control device 212 High frequency power supply 213 Cooling device 214 Drive device 1
215 Power control device 216 Drive device 2
218 Combustion gas 219 Vacuum pressure gauge 221 Filter 223 Dry pump 231 Left flange 232 Right flange 235 Thermocouple 236 Rail 241 Shield plate 242 Coil support 243 Coil 250 Electric furnace S1 Pretreatment process S2, S4, S6 Carbonization process S5 HF treatment S3 activation process.

Claims (7)

Graphene characterized by having irregularities containing minute silicon components and potassium components of 1 μm or less. ^{The graphene according to claim 1, wherein the graphene 113 has a specific surface area of 1170 m 2} / g to 1780 m ² / g, which is measured by a water vapor adsorption measurement method and has a specific surface area according to the BET method. The graphene according to any one of claims 1 to 2, wherein the graphene contains 14 wt% to 30 wt% of a silicon component. A graphene produced by using the graphene according to any one of claims 1 to 3 as a precursor and removing the silicon component and the potassium component of the carbon material. The graphene according to claim 4, wherein the carbon component is 97 wt% or more and the oxygen component is 0.9 wt% to 1.24 wt%. An induction heating device that supplies an inert gas and heats it by induction heating that generates a magnetic field by alternating current.
The storage container formed of a conductor that can be heated by induction heating,
A double pipe cooling device that cools the inside of the pipe by circulating water,
A graphene manufacturing device characterized by being equipped with. The graphene manufacturing apparatus according to claim 6, further comprising a lid formed of a conductor above the storage container and allowing gas generated from an object to pass through.