JP7276771B2 - Method for producing porous carbon and method for producing porous carbon molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing porous carbon and a method for producing a molded porous carbon body.

Porous carbon having pores with diameters on the order of microns or nanometers on its surface and having a high specific surface area is useful as an adsorbent. Examples of the method for producing this porous carbon include a method in which a phenol resin or the like is used as a carbon raw material and activated with steam or an alkaline substance to increase the specific surface area (Japanese Patent Application Laid-Open No. 2012-41199), and an organic resin such as magnesium oxide. Examples include a method of removing the oxide after mixing with an oxide (template particles) and carbonizing it (Japanese Patent Laid-Open No. 2016-41656).

In the conventional method for producing porous carbon described above, in addition to the step of carbonizing the raw material, it is necessary to perform an activation treatment with an alkaline substance and a treatment to remove the template particles, which reduces the production efficiency and increases the production cost. do.

In the above-described conventional method for producing porous carbon, voids are formed on the surface of the carbon by eroding the carbon. In such a method, the specific surface area is roughly proportional to the degree of erosion. On the other hand, if the degree of erosion is increased in order to increase the specific surface area, the space formed inside also increases, and the volume of the porous carbon itself increases. Porous carbon with increased bulk, ie, reduced bulk density, tends to have a smaller specific surface area per unit volume, even if the specific surface area per unit mass increases.

Considering the state of use of the porous carbon, for example, when it is used in a storage battery, the porous carbon is used by filling a container of a certain volume with the porous carbon. In other words, porous carbon is required to have a large specific surface area per unit volume as well as a large specific surface area per unit mass. For this reason, the porous carbon preferably has a high bulk density.

Furthermore, since a decrease in bulk density means a decrease in the strength of porous carbon, the bulk density of porous carbon is required to be high also from the viewpoint of durability.

JP 2012-41199 A JP 2016-41656 A

The present invention has been made based on the circumstances as described above. An object of the present invention is to provide a method for producing a porous carbon molded body.

In the above-described conventional method for producing porous carbon, a non-graphitizable carbon raw material such as phenol resin is generally used as a raw material for producing porous carbon. It is considered that this is mainly due to the fact that a porous body cannot be obtained when an inexpensive graphitizable carbon raw material is used. Although the cause of this difference is not clear, the present inventors speculate as follows. First, when a non-graphitizable carbon raw material is used, a randomly crosslinked aromatic polymer with a small number of laminated structures between aromatic rings is directly solid-phase carbonized. In the process, the voids formed between the carbon network planes function as micropores, and it is thought that a porous body is obtained. On the other hand, when an easily graphitizable carbon raw material is used, it is carbonized through a melt. In the melt, parallel alignment (stacking) of the aromatic rings is stable, so a stacked structure (mesophase, liquid crystal) between aromatic molecules is generated. Thereafter, the graphitizable carbon raw material is made infusible and carbonized in the solid phase. In this mesophase, voids between aromatic molecules are minimized, so solid-phase carbonization does not result in porosity. Based on the above considerations, the present inventors found that porous carbon can be produced by solid phase carbonization without passing through a melt even when using an easily graphitizable carbon raw material. perfected the invention.

That is, the method for producing porous carbon of the present invention includes a step of solidifying an easily graphitizable carbon raw material without passing through a melt, and a step of solid phase carbonizing the solid content after the solidification step. .

In the method for producing porous carbon, the easily graphitizable carbon raw material is solidified without melting, so that even if the easily graphitizable carbon raw material is used, a porous body can be obtained as a solid content. Therefore, by solid-phase carbonizing this solid content, porous carbon having a large specific surface area per unit volume can be produced at a low production cost. In addition, the porous carbon produced by the method for producing porous carbon has a high proportion of micropores, which are pores with a diameter of less than 2 nm, and has an increased bulk density.

The easily graphitizable carbon material preferably contains ashless coal. Compared to coal pitch obtained through dry distillation and distillation of coal, which is generally performed at 1000 ° C or higher, ashless coal obtained by extraction from coal at 400 ° C or lower contains many heteroatoms such as oxygen and has a laminated structure. hard. Therefore, by including ashless coal in the graphitizable carbon raw material, it is easy to obtain porous carbon having a large specific surface area per unit volume. In addition, since ashless coal has a high heteroatom content and a high molecular weight, the yield in the solid-phase carbonization process can be increased.

The solidification step includes dissolving the graphitizable carbon raw material in a good solvent, mixing the solution obtained in the dissolving step with a poor solvent for the graphitizable carbon raw material, and mixing the poor solvent. and a step of precipitating a solid content from the mixed liquid obtained in the step. In this way, by using the so-called poor solvent method, which includes the above-described steps, for the solidification step, porous carbon can be easily produced, and special equipment etc. are not required, so the production cost of porous carbon is reduced. can be further reduced.

The solidification step includes a step of mixing coal with a good solvent for ashless coal, a step of heating the slurry obtained in the good solvent mixing step to elute ashless coal from the coal into the good solvent, and A step of solid-liquid separation of the slurry obtained in the elution step, a step of mixing the solution obtained in the solid-liquid separation step with the poor solvent of the ashless coal, and a mixture obtained in the poor solvent mixing step It is preferable to have a step of precipitating the solid content from. The ashless coal can be eluted into a good solvent by the solvent extraction treatment of the coal in the elution step. Therefore, by using the solution in which the ashless coal is eluted in the good solvent as the solution in the poor solvent mixing step, there is no need to take out the ashless coal as a solid matter, so the production cost of the porous carbon can be further reduced.

It is preferable that the good solvent contains a nitrogen-containing compound and the poor solvent does not contain a nitrogen-containing compound. By including the nitrogen-containing compound in the good solvent in this way, the solubility of the graphitizable carbon raw material can be increased. In addition, by not including a nitrogen-containing compound in the poor solvent, it is possible to increase the deposition efficiency of the solid content. Therefore, by combining the good solvent and the poor solvent as described above, the production efficiency of the porous carbon can be enhanced.

The content of the graphitizable carbon raw material in the solution is preferably 5% by mass or more and 50% by mass or less, and the mass ratio of the poor solvent to the solution mixed in the poor solvent mixing step is 3 times. More than 20 times or less is preferable. By setting the content of the graphitizable carbon raw material within the above range, it is possible to increase the production efficiency of the porous carbon while reducing the undissolved graphitizable carbon raw material. Further, by setting the mass ratio of the poor solvent within the above range, it is possible to increase the production efficiency of the porous carbon while suppressing unnecessary use of the poor solvent.

The solidification step preferably includes a step of freezing a solution containing the graphitizable carbon raw material, and a step of drying the graphitizable carbon raw material after the freezing step in a frozen state. By using the so-called freeze-drying method, which includes the above-described steps, for the solidification step, porous carbon can be easily produced, and a lump-like bulk can be easily obtained.

The solidification step preferably includes a step of preparing a spinning solution containing the graphitizable carbon raw material, and a step of making the graphitizable carbon raw material fiber by discharging the spinning solution into a coagulating liquid. By using the so-called wet spinning method including the above-described steps for the solidification step, porous carbon can be easily produced, and fibrous porous carbon can be easily obtained.

The method for producing a porous carbon molded body of the present invention includes a step of solidifying an easily graphitizable carbon raw material without passing through a melt, a step of solid phase carbonizing the solid content after the solidification step, and the above and a step of pressure-molding the porous carbon after the solidification step so that the bulk density is 0.8 g/cm ³ or more.

In the method for producing a porous carbon molded body, the easily graphitizable carbon raw material is solidified without melting, so that even if the easily graphitizable carbon raw material is used, a porous body can be obtained as a solid content. Therefore, by solid-phase carbonizing this solid content, it is possible to produce a porous carbon molding having a large specific surface area per unit volume at a low production cost. In addition, the method for producing a porous carbon molded body has a high ratio of micropores, which are pores with a diameter of less than 2 nm, and can increase the bulk density. By making the bulk density equal to or higher than the above lower limit in the pressure molding process, a high capacitance per unit volume can be obtained when used as an electric double layer capacitor, for example.

Here, the term "easy graphitizable carbon material" refers to a carbon material that graphitizes when heat-treated at a high temperature of 2500° C. or higher under normal pressure. Moreover, "solid-phase carbonization" means carbonization without softening (melting).

A "good solvent" for a substance refers to a solvent in which the substance has a solubility of 5% by mass or more at 25°C, and a "poor solvent" refers to a solvent in which the substance has a solubility of less than 5% by mass at 25°C. point to

“Ash-free coal” (Hypercoal, HPC) is a type of modified coal obtained by modifying coal, and is modified coal in which ash and insoluble components are removed as much as possible from coal using a solvent. be. However, the ashless coal may contain ash as long as the fluidity and expansibility of the ashless coal are not significantly impaired. Generally, coal contains 7% by mass or more and 20% by mass or less of ash, but ashless coal may contain about 2% by mass, and in some cases about 5% by mass of ash. The term "ash content" means a value measured according to JIS-M8812:2004.

Also, the "bulk density" of a molded body refers to a value obtained by dividing the mass after molding by its volume.

INDUSTRIAL APPLICABILITY As described above, the method for producing porous carbon and the method for producing a porous carbon molded body according to the present invention provide porous carbon and porous carbon having a large bulk density and a large specific surface area per unit volume at a low production cost. A quality carbon molding can be produced.

FIG. 1 is a flow diagram showing a method for producing porous carbon according to one embodiment of the present invention. FIG. 2 is a flowchart showing a method for manufacturing a porous carbon molded body according to one embodiment of the present invention. FIG. 3 is a detailed flow diagram showing the solidification process of FIGS. 1 and 2; FIG. 4 is a detailed flow diagram showing a solidification process different from that of FIG. FIG. 5 is a detailed flow diagram showing a solidification process different from FIGS. 3 and 4. FIG. FIG. 6 is a detailed flow diagram showing a solidification process different from FIGS. 3, 4 and 5; FIG. 7 is a schematic diagram showing a schematic configuration of a wet spinning apparatus used in the solidification step of FIG.

[First embodiment]
A first embodiment of the method for producing porous carbon and the method for producing a molded porous carbon body according to the present invention will be described below.

As shown in FIG. 1, the method for producing porous carbon includes a solidification step S1 and a solid-phase carbonization step S2. Moreover, as shown in FIG. 2, the method for producing the porous carbon molded body includes a pressure molding step S3 in addition to the above-described solidification step S1 and solid phase carbonization step S2.

[Solidification step]
In the solidification step S1, the graphitizable carbon raw material is solidified without being melted.

Examples of the easily graphitizable carbon material include coal pitch, petroleum asphalt, and ashless coal. These raw materials may be used alone or in combination of two or more. Moreover, the graphitizable carbon raw material may be produced through a melt.

The easily graphitizable carbon material preferably contains ashless coal, and more preferably uses ashless coal alone. Compared to coal pitch obtained through dry distillation and distillation of coal, which is generally performed at 1000 ° C or higher, ashless coal obtained by extraction from coal at 400 ° C or lower contains many heteroatoms such as oxygen and has a laminated structure. hard. Therefore, by including ashless coal in the graphitizable carbon raw material, it is easy to obtain porous carbon having a large specific surface area per unit volume. In addition, since ashless coal has a high heteroatom content and a high molecular weight, the yield in the solid-phase carbonization process can be increased.

Ashless coal is a mixture of various molecules because it is a coal extract, and has a basic structure of polycyclic aromatics having heteroatoms such as oxygen and nitrogen. Molecules of such ashless coal have relatively planarity and high softening and melting properties because polycyclic aromatic molecules are planar. In the temperature rising process for carbonizing ashless coal, it usually becomes a softened and melted liquid state at around 400°C, and the carbonization reaction (liquid phase carbonization) proceeds at about 900°C. In this liquid-phase carbonization process, the ash-free coal molecules are layered in the planar part and become oriented molecular aggregates in order to stabilize the entire system. That is, ashless coal is a graphitizable carbon material (an easily graphitizable carbon material).

In the method for producing porous carbon and the method for producing a porous carbon compact, the solidification step S1 includes a dissolution step S11, a poor solvent mixing step S12, and a precipitation step S13, as shown in FIG.

<Dissolution process>
In the dissolving step S11, the graphitizable carbon material is dissolved in the good solvent.

The good solvent is not particularly limited as long as it can dissolve the graphitizable carbon material, but the good solvent preferably contains a nitrogen-containing compound. By including the nitrogen-containing compound in the good solvent in this manner, the solubility of the graphitizable carbon material can be increased.

Examples of the nitrogen-containing compounds include pyridine (C ₅ H ₅ N), quinoline (C ₉ H ₇ N), N-methylpyrrolidone (C ₅ H ₉ NO), and the like. Among them, pyridine is preferable because it has a high dissolving power and a relatively low boiling point and is easy to handle.

The lower limit of the content of the graphitizable carbon material in the solution after dissolution is preferably 5% by mass, more preferably 10% by mass. On the other hand, the upper limit of the content of the graphitizable carbon material is preferably 40% by mass, more preferably 30% by mass. If the content of the graphitizable carbon raw material is less than the lower limit, the good solvent may become excessive and the production efficiency of the porous carbon may decrease. Conversely, if the content of the graphitizable carbon raw material exceeds the above upper limit, the amount of undissolved graphitizable carbon raw material increases, and the yield of porous carbon may decrease.

<Poor solvent mixing step>
In the poor solvent mixing step S12, the solution obtained in the dissolving step S11 is mixed with the poor solvent for the graphitizable carbon raw material.

The poor solvent is not particularly limited as long as the solubility of the graphitizable carbon raw material is low, but a solvent that mixes well with the good solvent is preferable. Moreover, it is preferable that the poor solvent does not contain a nitrogen-containing compound. By not including a nitrogen-containing compound in the poor solvent in this manner, the deposition efficiency of the solid content can be enhanced. Moreover, the combination of the good solvent containing the nitrogen-containing compound and the poor solvent not containing the nitrogen-containing compound can particularly enhance the production efficiency of the porous carbon.

Examples of the poor solvent include water (H ₂ O), methanol (CH ₄ O), ethanol (C ₂ H ₆ O), acetone (C ₃ H ₆ O), toluene (C ₇ H ₈ ), hexane (C ₆ H ₁₄ ) and the like. When a highly polar nitrogen-containing compound is used as the good solvent, the poor solvent is preferably a highly polar one containing oxygen, which is easily mixed with the good solvent. Such poor solvents include water, methanol, ethanol, and acetone. When methylnaphthalene or the like is used as the good solvent, toluene or hexane is preferable as the poor solvent because the dissolving power of the graphitizable carbon material is sufficiently lower than that of methylnaphthalene or the like.

A method of mixing the solution and the poor solvent is not particularly limited, but a method of adding the solution to the poor solvent is preferable. By adding the graphitizable carbon raw material dissolved in the good solvent to a large amount of the poor solvent, the graphitizable carbon raw material instantly becomes a powdery solid content, so that the production efficiency of the porous carbon can be enhanced.

The lower limit of the mass ratio of the poor solvent to the solution mixed in the poor solvent mixing step S12 is preferably 3 times, more preferably 5 times. On the other hand, the upper limit of the mass ratio is preferably 20 times, more preferably 10 times. If the above mass ratio is less than the above lower limit, the amount of graphitizable carbon raw material that does not precipitate may increase, and the yield of porous carbon may decrease. Conversely, if the mass ratio exceeds the upper limit, the amount of the poor solvent is unnecessarily increased, which may lead to a decrease in production efficiency and an increase in production cost.

<Precipitation process>
In the precipitation step S13, the solid content is precipitated from the mixture obtained in the poor solvent mixing step S12.

Specifically, when the solution and the solvent are mixed as described above, a solid content is precipitated, and the precipitated solid content is, for example, separated by filtration and dried under reduced pressure.

In the solid content deposited in this way, pores with a diameter of less than 2 nm (micropores) account for the majority, and pores with a diameter of 2 nm or more and less than 50 nm (mesopores) and pores with a diameter of 50 nm or more (macropores) are compared. less meaningful. Therefore, the solid content has a high density relative to the specific surface area.

In addition, by using the so-called poor solvent method, which includes the above-described steps, in the solidification step S1, porous carbon can be easily produced, and no special apparatus or the like is required. Manufacturing costs can be further reduced.

[Solid phase carbonization step]
The solid phase carbonization step S2 solid phase carbonizes the solid content after the solidification step S1. Specifically, the solid content obtained in the solidification step S1 is heat-treated. Porous carbon is obtained by this carbonization. This solid-phase carbonization step S2 can be performed by a heating unit.

<Heating part>
The heating unit carbonizes the solid content by heating while substantially maintaining the aggregation state thereof (solid-phase carbonization). As the heating unit, for example, a known electric furnace or the like can be used, and the low-crystalline solid content is inserted into the heating unit, the inside is replaced with an inert gas, and then the inert gas is blown into the heating unit. Solid-phase carbonization of the solid content can be performed by heating. Examples of the inert gas include, but are not limited to, nitrogen and argon. Among them, nitrogen is preferable because it is inexpensive.

The lower limit of the heating temperature in the solid phase carbonization step S2 is preferably 600°C or higher, more preferably 900°C. On the other hand, the upper limit of the heating temperature is preferably 1300°C, more preferably 1100°C. If the heating temperature is less than the lower limit, carbonization and pore development may be insufficient. Conversely, if the heating temperature exceeds the above upper limit, the specific surface area (porosity) decreases, and there is a risk that the production cost will increase from the viewpoint of improving the heat resistance of the equipment and fuel consumption. In addition, the heating rate can be, for example, 0.01° C./min or more and 10° C./min or less.

Also, the lower limit of the heating time is preferably 10 minutes, more preferably 20 minutes. On the other hand, the upper limit of the heating time is preferably 10 hours, more preferably 8 hours. If the heating temperature is less than the above lower limit, carbonization may be insufficient. Conversely, if the heating time exceeds the above upper limit, the production efficiency of porous carbon may decrease.

<Infusibilization treatment>
In addition, infusibilization may be performed before performing solid-phase carbonization. This infusibilization treatment can prevent the solids from being fused to each other. The infusibilization is performed by heating in an oxygen-containing atmosphere using, for example, a known heating furnace. Air is generally used as the atmosphere containing oxygen.

The lower limit of the infusibilization treatment temperature when infusibilization is performed is preferably 150°C, more preferably 180°C. On the other hand, the upper limit of the infusibilizing treatment temperature is preferably 300°C, more preferably 280°C. If the infusibilizing treatment temperature is lower than the above lower limit, the infusibilizing may be insufficient, or the infusibilizing treatment may take a long time, resulting in inefficiency. Conversely, if the infusibilization treatment temperature exceeds the upper limit, the solid content may melt before being infusibilized. In addition, the heating rate can be, for example, 0.01° C./min or more and 10° C./min or less.

The lower limit of the infusibilizing treatment time when infusibilizing is performed is preferably 10 minutes, more preferably 20 minutes. On the other hand, the upper limit of the infusibilizing treatment time is preferably 120 minutes, more preferably 90 minutes. If the infusibilization treatment time is less than the above lower limit, infusibilization may be insufficient. Conversely, if the infusibilizing treatment time exceeds the upper limit, the manufacturing cost of the porous carbon may increase unnecessarily.

<Activation treatment>
In the method for producing porous carbon, porous carbon in which micropores occupy the majority can be obtained without activation treatment, but the micropores can be further increased by applying a mild activation treatment.

A known method can be used for the activation treatment. For example, after the heat treatment or at the same time as the heat treatment, CO 2 is used to partially gasify the surface of the solid content (C+CO ₂ →2CO↑) using an inert gas containing CO ₂ as _the inert gas. Activation can be used.

The CO ₂ concentration in the inert gas is not particularly limited, but the lower limit of the CO ₂ concentration is preferably 10% by mass. On the other hand, the upper limit of the CO ₂ concentration may be 100% by mass (pure CO ₂ ). If the CO ₂ concentration is less than the lower limit, treatment at a higher temperature and for a longer time is required to obtain the desired activation effect, which may increase production costs and reduce production efficiency. .

The weight reduction of the porous carbon due to CO ₂ activation is preferably 105% by mass or more and 150% by mass or less with respect to the weight reduction when the carbonization treatment is performed in an inert gas containing no CO ₂ . If the weight reduction is less than the lower limit, the activation effect (porous formation) may be insufficient. Conversely, if the weight reduction exceeds the upper limit, a large activation effect can be obtained, but the carbon is wasted unnecessarily, and there is a risk that the production efficiency will decrease.

<Porous carbon>
By using the method for producing porous carbon, porous carbon having pores with an average diameter of 0.5 nm or more and 2 nm or less can be produced, for example. The porous carbon obtained by the method for producing porous carbon is in the form of particles.

The above porous carbon can be suitably used as an adsorbent for gases such as nitrogen, hydrogen and carbon monoxide, as an adsorbent for water treatment, as an electronic component, and the like. Due to its high bulk density, the porous carbon can provide high performance per unit volume when used as an electrode for an EDLC (Electrical Double Layer Capacitor) or the like.

The characteristics of the porous carbon produced using the method for producing porous carbon will be described below.

The lower limit of the pore volume of the porous carbon is preferably 0.02 cm ³ /g, more preferably 0.1 cm ³ /g, and even more preferably 0.15 cm ³ /g. If the pore volume is less than the lower limit, it may be difficult to use as a porous material. On the other hand, although the upper limit of the pore volume is not particularly limited, it is usually about 0.5 cm ³ /g. The term "pore volume" refers to the accumulated pore volume when the pore distribution is measured by the HK method and the pores are assumed to be cylindrical.

It is preferable that the pores of the porous carbon have many micropores and few mesopores and macropores. That is, among the pores of the porous carbon, the Log differential pore volume of pores having a diameter of 0.5 nm or less is preferably 0.1 cm ³ /g or more, more preferably 0.15 cm ³ /g or more. In addition, the Log differential pore volume of pores having a diameter of 2 nm or more and 4 nm or less is preferably less than 0.05 cm ³ /g, more preferably less than 0.03 cm ³ /g. When the log differential pore volume of pores with a diameter of 0.5 nm or less is less than the above lower limit, or the log differential pore volume of pores with a diameter of 2 nm or more and 4 nm or less is above the above upper limit, the density of the porous carbon is low. and the mechanical strength may decrease. Although the upper limit of the Log differential pore volume of pores having a diameter of 0.5 nm or less is not particularly limited, it is usually about 0.5 cm ³ /g. In addition, the lower limit of the Log differential pore volume of pores with a diameter of 2 nm or more and 4 nm or less is preferably 0 cm ³ /g, and pores with a diameter of 2 nm or more and 4 nm or less do not have to be present. The "log differential pore volume of a pore" at a certain diameter is a value calculated as follows. First, the pore distribution is measured by the HK method. This measurement yields the cumulative pore volume distribution V with respect to the diameter D of the bottom surface when the pores are assumed to be cylindrical. Based on this distribution, the log differential pore volume can be calculated by dividing the differential pore volume dV between measurement points by the differential value d (LogD) of the pore diameter D treated as a logarithm.

Since the pores of the porous carbon are many micropores, the porous carbon is dense and has a large specific surface area per unit mass. The lower limit of the specific surface area per unit mass of the porous carbon is preferably 300 m ² /g, more preferably 350 m ² /g, and even more preferably 400 m ² /g. If the specific surface area per unit mass is less than the above lower limit, it may be difficult to use as a porous material. On the other hand, although the upper limit of the specific surface area per unit mass is not particularly limited, it is usually about 3000 m ² /g. The specific surface area per unit mass of the porous carbon can be adjusted by, for example, the content of the graphitizable carbon raw material in the solution, the type of good solvent or poor solvent, and the like.

[Pressure molding process]
In the pressure molding step S3, the porous carbon after the solid phase carbonization step S2, which is after the solidification step S1, is pressure molded so as to have a bulk density of 0.8 g/cm ³ or more.

As a molding method in the pressure molding step S3, known compression molding, extrusion molding, granulation method, or the like can be used.

This molding step S3 can be performed using a known molding machine. The size and shape of the cavity of the mold used in the molding machine are appropriately determined according to the purpose of use of the porous carbon.

Further, when the porous carbon is insufficient in flexibility, the molding in the pressure molding step S3 is preferably performed by adding a binder to the porous carbon. If the porous carbon is flexible, it can be molded without including a binder.

When molding is performed by adding a binder, it is preferable to use, as the binder, a substance that has a low carbon yield and is difficult to permeate into the pores of the porous carbon, such as water or a water-soluble polymer. Examples of the water-soluble polymer include starch, molasses, polyvinyl alcohol, and the like. By using a material having a low carbon yield and being difficult to permeate into the pores of the porous carbon as the binder, it is possible to suppress deterioration in the porosity of the obtained porous carbon molded body.

When molding is performed by adding a binder, the lower limit of the amount of the binder added to the obtained porous carbon molded body is preferably 2% by mass, more preferably 4% by mass. On the other hand, the upper limit of the amount of the binder added is preferably 10% by mass, more preferably 8% by mass. If the amount of the binder added is less than the lower limit, moldability may be insufficient. Conversely, if the amount of the binder added exceeds the upper limit, there is a risk that the manufacturing cost will become too high for the effect of improving moldability.

The lower limit of the bulk density of the porous carbon molded body after molding in the pressure molding step S3 is preferably 0.8 g/cm ³ , more preferably 0.9 g/cm ³ or more. On the other hand, the upper limit of the bulk density of the porous carbon molded body is preferably 1.1 g/cm ³ and more preferably 1.0 g/cm ³ . If the bulk density of the porous carbon molded body is less than the lower limit, the capacitance per unit volume may be insufficient when used as an EDLC electrode, for example. Conversely, if the bulk density of the porous carbon molded body exceeds the upper limit, the micropores may be crushed during molding to increase the bulk density, resulting in a decrease in the specific surface area per unit volume.

The lower limit of the molding pressure is preferably 0.8 ton/cm ² and more preferably 1.0 ton/cm ² . On the other hand, the upper limit of the molding pressure is preferably 3.0 ton/cm ² and more preferably 2.5 ton/cm ² . If the molding pressure is less than the lower limit, the bulk density of the resulting porous carbon molded body may be insufficient, and the strength and specific surface area per unit volume may be insufficient. Conversely, if the molding pressure exceeds the upper limit, the micropores of the solid content are likely to be crushed, and the specific surface area per unit volume of the resulting porous particles may decrease.

The pressurization time in the pressurization molding step S3 is appropriately determined from the viewpoint of stabilization of the shape of the porous carbon molded body after molding and production efficiency, and is, for example, 0.5 minutes or more and 3 minutes or less. .

In addition, from the viewpoint of manufacturing cost, molding of porous carbon is preferably performed at room temperature (for example, 25° C.) without heating. Alternatively, heating may be performed to improve moldability. The mold temperature at that time is preferably 200° C. or less. If the mold temperature exceeds the above upper limit, there is a risk that the production cost will increase too much for the improvement effect of the obtained porous carbon molded body, and that the porosity of the obtained porous carbon molded body will decrease. .

<Advantages>
In the method for producing porous carbon and the method for producing a porous carbon compact, the easily graphitizable carbon raw material is solidified without being melted. you get a body Therefore, by solid-phase carbonizing this solid content, it is possible to produce porous carbon and porous carbon moldings having a large specific surface area per unit volume at a low production cost. In addition, the porous carbon and the porous carbon molded body manufactured by the method for manufacturing the porous carbon and the method for manufacturing the porous carbon molded body have a high proportion of micropores, which are pores with a diameter of less than 2 nm, Bulk density can be increased.

[Second embodiment]
A second embodiment of the method for producing porous carbon and the method for producing a molded porous carbon body according to the present invention will be described below.

The method for producing porous carbon includes a solidification step S1 and a solid-phase carbonization step S2, as shown in FIG. 1, like the method for producing porous carbon in the first embodiment. Moreover, as shown in FIG. 2, the method for producing the porous carbon molded body includes a pressure molding step S3 in addition to the above-described solidification step S1 and solid phase carbonization step S2.

[Solidification step]
In the solidification step S1, the graphitizable carbon raw material is solidified without being melted.

In the present embodiment, the graphitizable carbon material is ashless coal.

In the method for producing porous carbon and the method for producing a porous carbon molded body, as shown in FIG. 4, the solidification step S1 includes a good solvent mixing step S21, an elution step S22, a solid-liquid separation step S23, It has a poor solvent mixing step S24 and a precipitation step S25.

<Good solvent mixing step>
In a good solvent mixing step S21, coal is mixed with a good solvent for ashless coal.

As the good solvent, the same solvent as in the first embodiment can be used.

This good solvent mixing step S21 can be performed by, for example, a coal input section, a solvent supply section, and a mixing section.

(Coal input part)
The coal input unit inputs coal into the mixing unit. A known coal hopper such as a normal pressure hopper that is used under normal pressure and a pressurized hopper that is used under normal pressure and under pressure can be used as the coal charging part.

Coal fed from the coal feeding part is coal that serves as a raw material for ashless coal. Coal of various qualities can be used as the coal. For example, bituminous coal with a high extraction rate of ashless coal and cheaper low-grade coal (sub-bituminous coal and lignite) are preferably used. When coal is classified by particle size, finely pulverized coal is preferably used. Here, "finely pulverized coal" means, for example, coal in which the mass ratio of coal having a particle size of less than 1 mm to the mass of the entire coal is 80% or more. Lump coal can also be used as the coal to be fed from the coal feeding part. Here, "lump coal" means coal in which the mass ratio of coal having a particle size of 5 mm or more to the mass of the entire coal is 50% or more. Lump coal maintains a large particle size of undissolved solid coal compared to finely pulverized coal, so that separation in a separation section, which will be described later, can be made more efficient. Here, "particle size (particle size)" refers to a value measured in accordance with the general rules for sieving test of JIS-Z8815:1994. For sorting coal according to particle size, for example, a metal mesh sieve specified in JIS-Z8801-1:2006 can be used.

As a minimum of the carbon content rate of the said low rank coal, 70 mass % is preferable. On the other hand, the upper limit of the carbon content of the low-grade coal is preferably 85% by mass, more preferably 82% by mass. If the carbon content of the low-rank coal is less than the lower limit, the elution rate of solvent-soluble components may decrease. Conversely, if the carbon content of the low-rank coal exceeds the upper limit, the cost of coal to be fed may increase.

As the coal to be fed from the coal feeding section to the mixing section, coal mixed with a small amount of solvent and slurried may be used. By charging slurried coal from the coal charging section into the mixing section, the coal can be easily mixed with the solvent in the mixing section, and the coal can be dissolved more quickly. However, if the amount of the solvent to be mixed at the time of slurrying is large, the amount of heat required to raise the temperature of the slurry to the elution temperature in the temperature raising section described later becomes unnecessarily large, which may increase the production cost.

(Solvent supply unit)
The solvent supply section supplies the solvent to the mixing section. The solvent supply section has a solvent tank that stores the solvent, and supplies the solvent from the solvent tank to the mixing section. The solvent supplied from the solvent supply section is mixed with the coal supplied from the coal supply section in the mixing section.

The solvent supplied from the solvent supply unit is the good solvent described above. When ashless coal is used as the easily graphitizable carbon material, the good solvent includes, in addition to the above solvents, methylnaphthalene oil, which is a distilled oil of by-product oil when coal is carbonized to produce coke, Naphthalene oil or the like can also be used.

(Mixing section)
The mixing section mixes the coal fed from the coal feeding section and the solvent fed from the solvent feeding section.

A preparation tank can be used as the mixing section. The solvent is supplied to the preparation tank through a supply pipe, and coal is added to the supplied solvent. In the preparation tank, the coal and solvent are mixed to prepare a slurry. In addition, the preparation tank has a stirrer, and the mixed state of the slurry is maintained by holding the mixed slurry while stirring it with the stirrer.

The coal concentration based on anhydrous coal in the slurry in the preparation tank is appropriately determined depending on the type of solvent and the like, but the lower limit of the coal concentration is preferably 5% by mass, more preferably 10% by mass. On the other hand, the upper limit of the coal concentration is preferably 65% by mass, more preferably 40% by mass. If the coal concentration is less than the lower limit, the amount of solvent-soluble components eluted in the elution step S22 is less than the amount of slurry processed, so the content of ashless coal contained in the liquid is insufficient. There is a possibility that it will be. Conversely, if the coal concentration exceeds the upper limit, the solvent-soluble components are likely to saturate in the solvent, which may reduce the elution rate of the solvent-soluble components.

The slurry prepared in the preparation tank of the mixing section is processed in the ashless coal elution step S22.

<Elution process>
In the elution step S22, ashless coal is eluted from the coal into the good solvent by heating the slurry obtained in the good solvent mixing step S21. The elution step S22 can be performed by a temperature raising section and an elution section.

(Temperature raising part)
The temperature raising unit raises the temperature of the slurry obtained in the good solvent mixing step S21.

The temperature raising unit is not particularly limited as long as it can raise the temperature of the slurry passing through it, and examples thereof include a resistance heating type heater and an induction heating coil. In addition, the temperature raising unit may be configured to raise the temperature using a heat medium, for example, it has a heating pipe arranged around the flow path of the slurry passing through the inside, and the heating pipe The temperature of the slurry may be raised by supplying a heat medium such as steam or oil.

The temperature of the slurry after the temperature is raised by the temperature raising unit is appropriately determined according to the solvent to be used, but should be at least the boiling point of the solvent or less. For example, when using methylnaphthalene as a solvent, the temperature is set to 300° C. or more and 400° C. or less in a pressure vessel. If the temperature of the slurry is below the above lower limit, the elution rate may decrease. Conversely, if the temperature of the slurry exceeds the upper limit, the solvent may be excessively vaporized, making it difficult to control the concentration of the slurry.

Moreover, although the pressure of the temperature raising part is not particularly limited, it can be normal pressure (0.1 MPa). For example, if methylnaphthalene is used as a solvent, the pressure in the pressure vessel may be 2 MPa or less.

(Elution part)
The elution section eluates coal components soluble in a solvent from the coal in the slurry obtained in the mixing section and heated in the temperature raising section. The main component of this solvent-soluble component is ashless coal. Here, "main component" means a component with the highest content, for example, a component with a content of 50% by mass or more.

An extraction tank can be used as the elution part, and the slurry after the temperature rise is supplied to this extraction tank. In the extraction tank, solvent-soluble coal components are eluted from the coal while maintaining the temperature and pressure of the slurry. Moreover, the said extraction tank has a stirrer. By stirring the slurry with this stirrer, the elution can be promoted.

The elution time in the elution part is not particularly limited, but is preferably 10 minutes or more and 120 minutes or less from the viewpoint of the extraction amount of solvent-soluble components and extraction efficiency.

<Solid-liquid separation step>
In the solid-liquid separation step S23, the slurry obtained in the elution step S22 is subjected to solid-liquid separation. Specifically, in the solid-liquid separation step S23, the slurry is separated into a solution in which solvent-soluble components are eluted and an extraction residue. This solid-liquid separation step S23 can be performed by a separation unit. The extraction residue mainly contains insoluble ash and insoluble coal in the extraction solvent, and further contains the extraction solvent.

(separation part)
As a method for separating the liquid component and the extraction residue in the separation unit, for example, a gravity sedimentation method, a filtration method, and a centrifugal separation method can be used, and a sedimentation tank, a filter, and a centrifugal separator are used, respectively.

The separation method will be described below using the gravity sedimentation method as an example. Gravity sedimentation is a separation method in which the extraction residue is sedimented using gravity in a sedimentation tank for solid-liquid separation. When the separation is performed by the gravity sedimentation method, the liquid portion in which the ashless coal is dissolved accumulates in the upper part of the sedimentation tank. This liquid portion is discharged after being filtered using a filter unit as necessary. On the other hand, the extraction residue is discharged from the lower part of the separation section.

Further, when the separation is performed by the gravity sedimentation method, the liquid component and the extraction residue can be discharged from the sedimentation tank while the slurry is continuously supplied into the separation section. This enables continuous solid-liquid separation processing.

The time for which the slurry is maintained in the separation section is not particularly limited, but can be, for example, 30 minutes or more and 120 minutes or less, and sedimentation separation in the separation section is performed within this time. In addition, when lump coal is used as coal, sedimentation separation is made efficient, so the time for maintaining the slurry in the separation section can be shortened.

The temperature and pressure in the separation section can be the same as those of the slurry after the temperature is raised by the temperature raising section.

<Poor solvent mixing step>
In the poor solvent mixing step S24, the solution obtained in the solid-liquid separation step S23 is mixed with the poor solvent for the ashless coal.

As described above, the main component of the solvent-soluble components eluted in this solution is ashless coal. That is, the above solution is obtained by dissolving ashless coal, which is an easily graphitizable carbon raw material, in a good solvent for ashless coal.

The content of the graphitizable carbon material (ashless coal) in the solution can be the same as the content of the graphitizable carbon material in the solution in the first embodiment. Moreover, as the poor solvent, the same solvent as in the first embodiment can be used.

The method for mixing the solution and the poor solvent is the same as the poor solvent mixing step S12 in the first embodiment.

<Precipitation process>
In the precipitation step S25, the solid content is precipitated from the liquid mixture obtained in the poor solvent mixing step S24. Since the precipitation step S25 is the same as the precipitation step S13 in the first embodiment, detailed explanation is omitted.

[Solid phase carbonization step and pressure molding step]
Since the solid phase carbonization step S2 and the pressure molding step S3 are the same as the solid phase carbonization step S2 and the pressure molding step S3 in the first embodiment, detailed description thereof is omitted. Moreover, the obtained porous carbon is also the same as the porous carbon in the first embodiment.

<Advantages>
In the method for producing porous carbon and the method for producing a porous carbon compact, the ashless coal can be eluted into a good solvent by the solvent extraction treatment of the coal in the elution step S21. Therefore, by using the solution in which the ashless coal is eluted in the good solvent as the solution in the poor solvent mixing step S24, there is no need to take out the ashless coal as a solid matter, so the production cost of the porous carbon can be further reduced.

[Third embodiment]
A third embodiment of the method for producing porous carbon and the method for producing a molded porous carbon body according to the present invention will be described below.

The method for producing porous carbon includes a solidification step S1 and a solid-phase carbonization step S2, as shown in FIG. 1, like the method for producing porous carbon in the first embodiment. Moreover, as shown in FIG. 2, the method for producing the porous carbon molded body includes a pressure molding step S3 in addition to the above-described solidification step S1 and solid phase carbonization step S2.

[Solidification step]
In the solidification step S1, the graphitizable carbon raw material is solidified without being melted.

As the graphitizable carbon raw material, the one described in the method for producing porous carbon in the first embodiment can be used. Hereinafter, as in the first embodiment, the case where ashless coal is used alone as the graphitizable carbon raw material will be described as an example, but this means that the graphitizable carbon raw material is limited to ashless coal. not something to do.

In the porous carbon production method and the porous carbon molding production method, the solidification step S1 includes a freezing step S31 and a drying step S32, as shown in FIG.

<Freezing process>
In the freezing step S31, the solution containing the graphitizable carbon raw material is frozen.

In this freezing step S31, first, a solution is prepared by dissolving the graphitizable carbon raw material in a solvent. Examples of the solvent include pyridine (C ₅ H ₅ N), tetrahydrofuran (C ₄ H ₈ O), dimethylformamide ((CH ₃ ) ₂ NCHO), N-methylpyrrolidone (C ₅ H ₉ NO) and the like. Among them, pyridine and tetrahydrofuran having a low boiling point, which have a high affinity with ashless coal and can reduce the load of the drying step S32 described later, are preferable.

The content of the graphitizable carbon raw material (ashless coal in the porous carbon production method) in the solution can be the same as the graphitizable carbon raw material in the solution of the first embodiment. Moreover, the method of eluting the ashless coal, which is the easily graphitizable carbon material, into the good solvent can be the same as the elution method of the first embodiment.

The solution is then cooled to a temperature below the melting point of the solvent and frozen. For example, when using tetrahydrofuran (melting point -108°C), cool to -130°C and freeze.

The temperature difference between the melting point of the solvent and the cooling temperature is not particularly limited, but can be, for example, 10° C. or higher and 50° C. or lower. If the temperature difference is less than the lower limit, it takes time to freeze, which may reduce production efficiency. Conversely, if the temperature difference exceeds the upper limit, energy is unnecessarily required for cooling, which may increase the manufacturing cost.

<Drying process>
In the drying step S32, the graphitizable carbon raw material after the freezing step S31 is dried in a frozen state.

In this step, the solvent is sublimated without being melted by reducing the pressure while maintaining the freezing temperature in the freezing step S31. Then, if it returns to normal temperature (for example, 25 degreeC), dry solid content will be obtained. The main component of this solid content is ashless coal, which is an easily graphitizable carbon material.

The pressure for reducing the pressure is not particularly limited as long as it is a pressure that allows the solvent to be sublimated. If the pressure is less than the lower limit, the cost for reducing the pressure increases, which may increase the manufacturing cost of the porous carbon. Conversely, if the pressure exceeds the upper limit, the amount of solvent that evaporates from the melt increases, and the porosity of the obtained porous carbon may deteriorate.

[Solid phase carbonization step and pressure molding step]
Since the solid phase carbonization step S2 and the pressure molding step S3 are the same as the solid phase carbonization step S2 and the pressure molding step S3 in the first embodiment, detailed description thereof is omitted. Moreover, the obtained porous carbon is also the same as the porous carbon in the first embodiment.

<Advantages>
If the freezing and solidification is performed in the freezing step S31 in this manner, the lamination (crystallization) of the graphitizable carbon raw material is difficult to proceed. Then, since the solid of the graphitizable carbon raw material is obtained without passing through the melt in the drying step S32, it is possible to obtain a shaped solid in which crystallization has not progressed despite the graphitizable carbon raw material. can.

In addition, by using a so-called freeze-drying method that includes a freezing step S31 and a drying step S32 in the solidification step S2, porous carbon can be easily produced, and bulk mass can be easily obtained.

[Fourth embodiment]
A fourth embodiment of the method for producing porous carbon and the method for producing a porous carbon molded body according to the present invention will be described below.

The method for producing porous carbon includes a solidification step S1 and a solid-phase carbonization step S2, as shown in FIG. 1, like the method for producing porous carbon in the first embodiment. Moreover, as shown in FIG. 2, the method for producing the porous carbon molded body includes a pressure molding step S3 in addition to the above-described solidification step S1 and solid phase carbonization step S2.

[Solidification step]
In the solidification step S1, the graphitizable carbon raw material is solidified without being melted.

As the graphitizable carbon raw material, the one described in the method for producing porous carbon in the first embodiment can be used. Hereinafter, as in the first embodiment, the case where ashless coal is used alone as the graphitizable carbon raw material will be described as an example, but this means that the graphitizable carbon raw material is limited to ashless coal. not something to do.

In the method for producing porous carbon and the method for producing a porous carbon molded body, the solidification step S1 includes a preparation step S41 and a fiberization step S42, as shown in FIG.

<Preparation process>
In the preparation step S41, a spinning solution containing the graphitizable carbon raw material is prepared.

Specifically, a spinning solution is prepared by dissolving the graphitizable carbon raw material in a solvent. As the solvent, the good solvent described in the first embodiment can be used.

In addition, the content of the graphitizable carbon raw material (ashless coal in the porous carbon production method) in the solution can be the same as the graphitizable carbon raw material in the solution of the first embodiment. Moreover, the method of eluting the ashless coal, which is the easily graphitizable carbon material, into the good solvent can be the same as the elution method of the first embodiment.

<Fiberization process>
In the fiberization step S42, the graphitizable carbon raw material is fiberized by discharging the spinning solution into the coagulating liquid. As the coagulating liquid, the poor solvent described in the first embodiment can be used.

The fiberization step S42 can be performed using a wet spinning apparatus as shown in FIG. 7, for example. First, as shown in FIG. 7, the spinning solution X is discharged from the syringe N in the coagulating solution Y. As shown in FIG. The solvent in the spouted spinning solution X dissolves in the coagulating solution Y, and as a result, the graphitizable carbon raw material is covered with the coagulating solution Y. As a result, the graphitizable carbon raw material rapidly solidifies into a solid content W. This solid content W is taken up by rollers R and made into fibers.

[Solid phase carbonization step and pressure molding step]
Since the solid phase carbonization step S2 and the pressure molding step S3 are the same as the solid phase carbonization step S2 and the pressure molding step S3 in the first embodiment, detailed description thereof is omitted. Further, the obtained porous carbon is also the same as the porous carbon in the first embodiment except that it is fibrous, so detailed explanation is omitted.

<Advantages>
Due to the rapid solidification in the fiber processing step S42, lamination (crystallization) of the graphitizable carbon raw material is difficult to progress. Therefore, in spite of being an easily graphitizable carbon raw material, it is possible to obtain a shaped solid that is shaped into a fibrous shape with few layers.

Moreover, fibrous porous carbon can be easily obtained by using the so-called wet spinning method including the preparation step S41 and the fiberization step S42 in the solidification step S1.

[Other embodiments]
In addition, this invention is not limited to the said embodiment.

In the second embodiment, the configuration in which the mixing unit in the good solvent mixing step has a preparation tank has been described, but the mixing unit is not limited to this configuration. good too. For example, when the mixing is completed by a line mixer, the preparation tank may be omitted and the line mixer may be provided between the supply pipe and the separating section. Thus, the device configuration used in each step is not limited to the above embodiment.

In addition, in the above embodiment, the case of using the poor solvent method, the freeze-drying method, and the wet spinning method as the solidification process has been described. can also be used.

In the above-described embodiment, the solidification step, the solid phase carbonization step, and the pressure molding step are performed in this order as the method for manufacturing the porous carbon molded body. may change their order. That is, the method for producing a porous carbon molded body of the present invention includes the case where the solidification step, pressure molding step and solid phase carbonization step are performed in this order.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
Ashless coal produced by solvent extraction of bituminous coal was prepared as an easily graphitizable carbon raw material. Table 1 shows the elemental analysis values of this ashless coal. Also, pyridine (C ₅ H ₅ N, boiling point 115° C.) was prepared as a good solvent. The ashless coal was dissolved in the good solvent, and the ashless coal content in the solution was adjusted to 15% by mass.

In Table 1, the oxygen content of ashless coal means the content of components other than carbon, hydrogen, nitrogen and sulfur, and is obtained by subtracting the content of carbon, hydrogen, nitrogen and sulfur from 100% by mass.

2.0 L of water was prepared as a poor solvent. 100 g of the above solution was added to the stirred poor solvent to precipitate a solid content. Then, the precipitated solid content was separated by filtration and dried under reduced pressure.

Further, the temperature was raised to 900° C. at a temperature elevation rate of 5° C./min in a nitrogen atmosphere, and heat treatment (solid-phase carbonization) was performed for 30 minutes to produce a carbon material of Example 1.

[Example 2]
A carbon material of _{Example 2} was prepared in the same manner as in Example 1, except that quinoline ( _C9H7N , boiling point 238°C) was used as a good solvent and ethanol ( _C2H6O , boiling point 78°C) was used as a poor solvent. manufactured.

[Example 3]
A spinning solution was prepared by dissolving the same ashless coal as in Example 1 in pyridine. The content of ashless coal in the spinning solution was 30% by mass. 100 g of this spinning solution was discharged from a syringe with an inner diameter of 1.1 mm into 2.0 L of ethanol to obtain a fibrous solid content. The obtained solid content was subjected to solid phase carbonization under the same conditions as in Example 1 to produce a carbon material of Example 3.

[Comparative Example 1]
After crushing the same ashless coal as in Example 1 to a particle size of 250 μm or less, the temperature was raised to 900° C. at a heating rate of 5° C./min in a nitrogen atmosphere, and heat treatment (carbonization) was performed for 30 minutes, A carbon material of Comparative Example 1 was produced.

[Comparative Example 2]
Ashless coal of the same kind as in Example 1 was heated to 280° C. in a nitrogen atmosphere to melt the ashless coal (melting). This melt was pressurized and discharged from a nozzle with a diameter of 0.5 mm, and the discharged fibers were wound up to obtain fibrous solids. The obtained solid content was carbonized under the same conditions as in Example 1 to produce a carbon material of Comparative Example 2.

[Reference example 1]
Commercially available coconut shell activated carbon powder was prepared and used as the carbon material of Reference Example 1. Coconut husk is non-graphitizable carbon, and the specific surface area of this activated carbon powder is increased by activation treatment.

[Evaluation method]
The carbon materials of Examples 1 to 3, Comparative Example 1, Comparative Example 2, and Reference Example 1 thus obtained were subjected to the following measurements. Table 2 shows the results.

<Specific surface area>
The specific surface area was measured by the BET method.

<Capacitance>
The obtained carbon material, acetylene black as a conductive agent, and polytetrafluoroethylene (PTFE) as a binder were mixed at a mass ratio of 8:1:1, and molded into a coin shape to form an EDLC. An electrode for

The thickness of the obtained electrode was measured, and the volume was calculated by multiplying by the electrode area. In addition, using a battery charging/discharging device ("HJ1001SD8" manufactured by Hokuto Denko Co., Ltd.), charging characteristics in a 40% by mass sulfuric acid electrolyte were measured to determine the capacitance at 50 mA/h.

In Table 2, "ND" for specific surface area means that it was below the limit of measurement. Also, "-" means unmeasured.

From Table 2, the carbon materials of Examples 1 to 3, in which graphitizable carbon was solid-phase carbonized without passing through the melt, were compared to Comparative Examples 1 to 3, in which graphitizable carbon was carbonized via the melt. It can be seen that the carbon material has a larger specific surface area than the carbon material of Comparative Example 2 and is porous carbon.

On the other hand, in the carbon material of Comparative Example 1, it is considered that carbon having pores could not be obtained because normal carbonization was performed via the melt. In addition, in the carbon material of Comparative Example 2, the carbonization itself is performed without softening (melting). It is believed that carbon with pores was not obtained.

From the above, it can be said that even in the case of using graphitizable carbon raw material, porous carbon can be produced by solid-phase carbonization without passing through the melt.

Further, when comparing Example 1 and Reference Example 1, although Example 1 has a smaller specific surface area, the electrostatic capacity when an EDLC electrode is produced is rather large. From this, it can be seen that porous carbon obtained by solid-phase carbonization using an easily graphitizable carbon raw material without passing through a melt can produce an EDLC electrode that is rich in micropores and suitable for charging. I understand.

INDUSTRIAL APPLICABILITY As described above, the method for producing porous carbon and the method for producing a porous carbon molded body according to the present invention provide porous carbon and porous carbon having a large bulk density and a large specific surface area per unit volume at a low production cost. A quality carbon molding can be produced.

X Spinning solution Y Coagulating solution N Syringe R Roller W Solid content

Claims (10)

a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step under atmospheric pressure ,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
a dissolving step of dissolving the graphitizable carbon raw material in the good solvent;
a poor solvent mixing step of mixing the solution obtained in the dissolving step with a poor solvent for the graphitizable carbon raw material;
and a deposition step of depositing a powdery solid content from the mixed solution obtained in the poor solvent mixing step. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step under atmospheric pressure ,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
A good solvent mixing step of mixing coal with a good solvent for ashless coal;
An elution step of eluting ashless coal from the coal into the good solvent by heating the slurry obtained in the good solvent mixing step;
A solid -liquid separation step of solid-liquid separation of the slurry obtained in the elution step;
a poor solvent mixing step of mixing the solution obtained in the solid-liquid separation step with a poor solvent for the ashless coal;
and a deposition step of depositing a powdery solid content from the mixed solution obtained in the poor solvent mixing step. The good solvent contains a nitrogen-containing compound,
3. The method for producing porous carbon according to claim 1, wherein the poor solvent does not contain a nitrogen-containing compound. The content of the graphitizable carbon raw material in the solution is 5% by mass or more and 50% by mass or less,
4. The method for producing porous carbon according to claim 1, wherein a mass ratio of said poor solvent to said solution mixed in said poor solvent mixing step is 3 times or more and 20 times or less. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
a freezing step of freezing a solution containing the graphitizable carbon raw material;
and a drying step of drying the graphitizable carbon raw material after the freezing step in a frozen state. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step so that the pore volume is 0.02 cm ³ /g or more,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
a preparation step of preparing a spinning solution containing the graphitizable carbon raw material;
A fiberization step of fiberizing the graphitizable carbon raw material by discharging the spinning solution into the coagulating solution. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step under atmospheric pressure ;
A pressure molding step of pressure molding the porous carbon after the solidification step so that the bulk density is 0.8 g / cm ³ or more,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
a dissolving step of dissolving the graphitizable carbon raw material in the good solvent;
a poor solvent mixing step of mixing the solution obtained in the dissolving step with a poor solvent for the graphitizable carbon raw material;
and a deposition step of depositing a powdery solid content from the mixed liquid obtained in the poor solvent mixing step. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step under atmospheric pressure ;
A pressure molding step of pressure molding the porous carbon after the solidification step so that the bulk density is 0.8 g / cm ³ or more,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
A good solvent mixing step of mixing coal with a good solvent for ashless coal;
An elution step of eluting ashless coal from the coal into the good solvent by heating the slurry obtained in the good solvent mixing step;
A solid -liquid separation step of solid-liquid separation of the slurry obtained in the elution step;
a poor solvent mixing step of mixing the solution obtained in the solid-liquid separation step with a poor solvent for the ashless coal;
and a deposition step of depositing a powdery solid content from the mixed liquid obtained in the poor solvent mixing step. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step;
A pressure molding step of pressure molding the porous carbon after the solidification step so that the bulk density is 0.8 g / cm ³ or more,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
a freezing step of freezing a solution containing the graphitizable carbon raw material;
and a drying step of drying the graphitizable carbon raw material after the freezing step in a frozen state. a solidification step of solidifying the graphitizable carbon raw material without passing through the melt;
A solid phase carbonization step of solid phase carbonizing the solid content after the solidification step so that the pore volume is 0.02 cm ³ /g or more;
A pressure molding step of pressure molding the porous carbon after the solidification step so that the bulk density is 0.8 g / cm ³ or more,
Coal pitch, petroleum asphalt and ashless coal are used alone or in combination of two or more as the easily graphitizable carbon material,
The solidification step is
a preparation step of preparing a spinning solution containing the graphitizable carbon raw material;
and a fiberization step of fiberizing the graphitizable carbon raw material by discharging the spinning solution into the coagulating liquid.

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