JP5770550B2 - Activated carbon and manufacturing method thereof - Google Patents

Description

  The present invention relates to activated carbon having a reduced content of silicon component, and a method for producing the same.

  Activated carbon is used for various adsorption applications because of its high specific surface area and developed pore structure, and in recent years, it has been actively developed into electronic materials such as electrodes for electric double layer capacitors. However, activated carbon remains a metal component contained in a carbon-containing material (for example, pitch) used as a raw material or a metal component derived from an activator (for example, potassium hydroxide) used for activation treatment. It has been known. Since the metal component remaining in the activated carbon may interfere with the performance of the adsorbent or the electronic material, a method for removing such a metal component has been proposed.

  For example, Patent Document 1 proposes that when a fibrous activated carbon is produced using a metal-containing pitch as a raw material, the activated material is washed with an acid or an alkali to remove the metal or metal compound on the activated carbon surface. Yes. Note that Patent Document 1 shows that a metal component can be removed only by acid cleaning (see Patent Document 1 (Table 1)). Patent Document 2 proposes that, when a waste tire is used as a raw material, the activated material is treated with a hydrochloric acid solution and further washed with water or a dilute alkaline solution in order to remove heavy metal components derived from the waste tire. ing. Patent Document 2 shows that the metal component can be removed by a combination of acid cleaning and water cleaning (see Patent Document 2 (paragraphs [0016] to [0020])).

  Patent Document 3 proposes that when producing activated carbon for water treatment, the alkali metal oxide contained in the activation product is neutralized with an acid, and the acid retained in the activated carbon is removed by alkali washing. . In Patent Document 3, since the purpose is not the removal of the metal component but the neutralization, the hydrochloric acid aqueous solution used has a low concentration of 0.01 to 0.15 N, and the alkaline solution is also 0.1%. The one with a low concentration of 01 standard is used (see Patent Document 3 ([Claim 1], [Table 3])). Patent Document 4 proposes that the total content of alkali metal is 100 ppm or less by washing the activation product with a liquid containing a basic substance and further washing with hydrochloric acid water (Patent Document 4). (See Examples B1, D5)). In Patent Document 4, in order to reduce the alkali metal content of activated carbon, a basic substance not containing an alkali metal is used as a basic substance used for cleaning (Patent Document 4 (page 10, page 13). To line 19)).

JP 2003-217882 A Japanese Patent No. 3376431 Japanese Patent No. 4272586 International Publication No. 2004/011371

  As a result of investigations by the present inventors, activated carbon obtained by the conventional production method still contains ash, and this ash contains a large amount of silicon (Si) components derived from raw materials that are difficult to remove by acid cleaning. It became clear that Such a silicon component, like other metal impurities (Fe, K, Ni, Cu, etc.), for example, in an electric double layer capacitor electrode, decomposes the electrolyte used to reduce the capacity, The possibility of increasing the resistance is low. However, if the silicon content is high, the ratio of the carbon component contributing to the formation of the electric double layer in the activated carbon is decreased, so that the specific surface area of the activated carbon is decreased, which causes a decrease in capacitance.

  However, as in Patent Documents 1 and 2, although the metal component on the activated carbon surface can be removed only by acid cleaning, the activated carbon having a high specific surface area has a problem that the ash present in the pores cannot be sufficiently removed. In addition, when the acid component or alkali component of the cleaning liquid is at a low concentration as in Patent Document 3 or when a basic component other than an alkali metal is used as the basic component as in Patent Document 4, the ash content is sufficient. There is a problem that it cannot be removed.

  This invention is made | formed in view of the said situation, and it aims at providing the manufacturing method which can remove the ash content contained in activated carbon effectively, and can obtain the activated carbon with which silicon content was reduced easily. Another object of the present invention is to provide activated carbon suitable for an electric double layer capacitor electrode having a low silicon content, high capacitance, and low electrical resistance.

The method for producing activated carbon according to the present invention that has solved the above-described problem is that the activated material obtained by activating the carbon raw material is an alkaline solution having an alkali metal hydroxide concentration of 5 to 30% by mass and an acid component concentration. It is characterized by wash | cleaning in this order or the reverse order with the acidic solution which is 3-20 mass%. The washing is preferably carried out with an alkaline solution and then with an acidic solution. The activation treatment is preferably steam activation. The carbon raw material is preferably a carbonized paper phenol resin laminate.
Moreover, the activated carbon of the present invention is characterized in that the silicon content is 200 ppm to 3000 ppm. The activated carbon preferably has a specific surface area of 1600 m ² / g or more and an average pore diameter of 2 nm or more. The present invention also includes an electric double layer capacitor electrode using the activated carbon as an electrode material, and an electric double layer capacitor including the electrode.

According to the production method of the present invention, ash can be effectively removed by washing the activated material with an acidic solution and an alkali metal hydroxide solution having a predetermined concentration, and the silicon content is reduced. Activated carbon can be easily obtained.
In addition, if activated carbon having a low silicon content is used for an electrode for an electric double layer capacitor, an electric double layer capacitor having a high capacitance and a reduced electric resistance can be obtained.

It is a schematic diagram for demonstrating the electric double layer capacitor manufactured using the activated carbon of a manufacture example.

  The gist of the method for producing activated carbon of the present invention is to wash an activated product obtained by activating a carbon raw material with an alkaline solution and an acidic solution having a predetermined concentration. By doing so, it is possible to effectively remove ash (silicon component) that could not be removed by washing with only an alkaline solution or washing with only an acidic solution, or washing with a low-concentration alkaline solution or acidic solution.

  Examples of the carbon raw material include woody materials (wood, sawdust, coconut shell, etc.), cellulosic fibers (paper, cotton fibers, etc.), synthetic resins (phenol resin, furan resin, polyvinyl chloride, polyimide, polyacrylonitrile (PAN), etc.) Carbonaceous materials such as petroleum pitch, coal tar pitch, mesophase pitch, and composites thereof; and carbides such as coal, petroleum coke, coal coke, petroleum pitch coke, coal pitch coke, and charcoal.

  As the carbon raw material, a carbon raw material (hereinafter, sometimes referred to as “mesopore forming raw material”) in which relatively large pores (mesopores: pores having a diameter of more than 2.0 nm and less than 50 nm) are easily formed is used. It is preferable to use a composite with a carbon raw material (hereinafter sometimes referred to as “micropore forming raw material”) in which small pores (micropores: pores having a diameter of 2.0 nm or less) are easily formed. If a composite of a mesopore forming raw material and a micropore forming raw material is used as the carbon raw material, activated carbon having a good balance of micropores and mesopores can be obtained by a single activation treatment without performing the activation treatment multiple times. . Activated carbon having a good balance of micropores and mesopores has a good balance between the amount of adsorption and the moving speed of the adsorbed material. For example, when used as an electrode material, an electric double layer capacitor exhibiting high capacitance and low resistance can be obtained. can get.

  Examples of the mesopore-forming raw material include cellulose-based raw materials such as cellulose-based fibers and woody materials. Examples of the micropore forming raw material include synthetic resin raw materials such as phenol resin and furan resin. At least one or more of these mesopore forming raw materials and micropore forming raw materials are used. In addition, what is necessary is just to change suitably the compounding ratio of a mesopore formation raw material and a micropore formation raw material according to the physical property of the desired activated carbon. Examples of the composite of the mesopore forming raw material and the micropore forming raw material include a paper phenol resin laminate.

  When the carbonaceous material is used as the carbon material, it is preferable to use a carbonized carbonized material (for example, a carbonized paper phenol resin laminate). Carbonization of the carbonaceous material is usually performed by heat treatment under an inert gas atmosphere. The temperature of the carbonization treatment is preferably 400 ° C. or higher, more preferably 500 ° C. or higher, preferably 950 ° C. or lower, more preferably 900 ° C. or lower. Further, the carbonization time is preferably 0.5 hours or longer, more preferably 1.0 hours or longer, 4.0 hours or shorter, more preferably 3.0 hours or shorter.

  The carbon raw material preferably has an average particle size of 10 mm or less, more preferably 5 mm or less, and even more preferably 2 mm or less. The lower limit of the average particle size of the carbon raw material is not particularly limited, but if the average particle size is too small, the handling of the powder tends to be poor (for example, the powder will rise during operation). Therefore, the average particle diameter of the carbon raw material is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more. The average particle diameter is a volume-based median obtained by measuring a sample dispersed in water with a laser diffraction particle size distribution measuring apparatus (for example, “SALD (registered trademark) -2000” manufactured by Shimadzu Corporation). Is the diameter.

  As the activation treatment, both chemical activation (for example, alkali activation) and gas activation (for example, water vapor activation) can be employed, and both chemical activation and gas activation may be performed. Moreover, the activation process may be performed only once or multiple times. Among these, steam activation is preferable because adhesion of chemical components (such as alkali metals) to the activation product can be suppressed. In the steam activation, the activation raw material is heated to a predetermined temperature and then activated by supplying steam. It is preferable to heat the activation raw material in an inert gas atmosphere. Note that nitrogen, argon, helium, or the like can be used as the inert gas.

  The temperature at the time of activation treatment (furnace temperature) is preferably 400 ° C. or higher, more preferably 450 ° C. or higher, preferably 1500 ° C. or lower, more preferably 1300 ° C. or lower. Moreover, the heating time at the time of performing an activation process has preferable 0.5 hours or more, More preferably, it is 1.0 hours or more, 10 hours or less are preferable, More preferably, it is 5 hours or less.

  50 mass parts or more are preferable with respect to 100 mass parts of carbon raw materials, as for the total amount of the water vapor | steam supplied during an activation process, More preferably, it is 100 mass parts or more, More preferably, it is 200 mass parts or more, and shall be 10000 mass parts or less. More preferably, it is 5000 parts by mass or less, and still more preferably 3000 parts by mass or less. If the total amount of water vapor to be supplied is 50 parts by mass or more with respect to 100 parts by mass of the carbon raw material, pore formation by the activation reaction is better, and if it is 10000 parts by mass or less, the activation reaction proceeds more efficiently. Productivity can be improved.

  As an aspect for supplying water vapor, either an aspect for supplying water vapor without dilution or an aspect for supplying water vapor diluted with an inert gas can be used, but in order to advance the activation reaction efficiently, it is inactive. An embodiment in which the gas is supplied after being diluted with a gas is preferable. When supplying water vapor diluted with an inert gas, the water vapor partial pressure in the mixed gas (total pressure 101.3 kPa) is preferably 40 kPa or more, more preferably 50 kPa or more, and further preferably 70 kPa or more.

  In the method for producing activated carbon of the present invention, the activation product is washed with an alkaline solution and an acidic solution. The cleaning with the alkaline solution and the cleaning with the acidic solution may each be performed only once or a plurality of times. In addition, it is preferable to carry out once each from the viewpoint of economy. The order of washing with the alkaline solution and washing with the acidic solution is not particularly limited, but it is preferable to wash with the acidic solution after washing with the alkaline solution. By carrying out like this, while removing the ash (silicon component) in the obtained activated carbon effectively, an alkali metal component (for example, potassium (K) component) can also be reduced.

  Examples of the alkali metal hydroxide used in the alkaline solution include lithium hydroxide, sodium hydroxide, and potassium hydroxide. These alkali metal hydroxides may be used alone or in combination of two or more. Among these, potassium hydroxide is preferable. The solvent for the alkaline solution is not particularly limited, but water is preferable.

  The alkali metal hydroxide concentration in the alkaline solution is 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, and 30% by mass or less, preferably 25% by mass or less, more preferably. It is 20 mass% or less. Further, the alkali metal hydroxide concentration in the alkaline solution is preferably 0.9 mol / L or more, more preferably 1.5 mol / L or more, still more preferably 2.5 mol / L or more, and 5 mol / L or less. Preferably, it is 4 mol / L or less, more preferably 3.5 mol / L or less.

  The washing time with the alkaline solution is preferably 0.3 hours or more, more preferably 0.5 hours or more, further preferably 0.7 hours or more, preferably 2 hours or less, more preferably 1.5 hours or less, More preferably, it is 1.2 hours or less. The temperature of the alkaline solution is preferably 30 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 70 ° C. or higher. Although the upper limit of the temperature of an alkaline solution is not specifically limited, It is below the boiling point. The activation product washed with the alkaline solution is preferably washed well with water to remove the alkaline component.

  Examples of the acid component used in the acidic solution include inorganic acids such as hydrochloric acid, carbonic acid, sulfuric acid, and nitric acid; and organic acids such as formic acid, acetic acid, and citric acid. These acid components may be used alone or in combination of two or more. Among these, inorganic acids are preferable, and hydrochloric acid is more preferable. The solvent of the acidic solution is not particularly limited, but water is preferable.

  The acid component concentration in the acidic solution is 3% by mass or more, preferably 4% by mass or more, more preferably 5% by mass or more, 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass. It is as follows. The acid component concentration in the acidic solution is preferably 0.9 mol / L or more, more preferably 1.1 mol / L or more, still more preferably 1.3 mol / L or more, and preferably 5 mol / L or less. Preferably it is 4 mol / L or less, More preferably, it is 2.5 mol / L or less.

  The washing time with the acidic solution is preferably 0.3 hours or more, more preferably 0.5 hours or more, further preferably 0.7 hours or more, preferably 2 hours or less, more preferably 1.5 hours or less, More preferably, it is 1.2 hours or less. The temperature of the acidic solution is preferably 30 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 70 ° C. or higher. Although the upper limit of the temperature of an acidic solution is not specifically limited, It is below the boiling point. It is preferable that the activation product washed with the acidic solution is washed well with water to remove the acid component.

  The activated carbon that has been washed with an acidic solution and washed with an alkaline solution may be further washed with water and pulverized. By washing with water, metal impurities, ash, etc. can be further removed. The pulverization is performed using a disk mill, a ball mill, a bead mill or the like. In addition, what is necessary is just to adjust the particle diameter of activated carbon suitably according to a use.

  The activated carbon obtained by the production method of the present invention has a reduced content of silicon components. The lower the silicon content, the greater the proportion of the carbon component that contributes to the formation of the electric double layer in the activated carbon, so if used for an electrode for an electric double layer capacitor, the capacitance of the resulting electric double layer capacitor is improved, Electric resistance is reduced. The activated carbon has a silicon content of 3000 ppm or less, preferably 2900 ppm or less, more preferably 2850 ppm or less. In addition, although the minimum of silicon content is not specifically limited, It is 200 ppm or more, Preferably it is 300 ppm or more, More preferably, it is 500 ppm or more. When the silicon content is less than 500 ppm, the effect of improving the electrostatic capacity and the effect of reducing the electric resistance when used in the electric double layer capacitor are saturated. Moreover, in order to make silicon content less than 200 ppm, it is necessary to repeat washing | cleaning, and it is not economical.

  The ash content of the activated carbon is preferably 2.5% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. If the ash content is low, not only silicon but also metal impurities are reduced. Therefore, when used as an electrode for an electric double layer capacitor, decomposition of the electrolytic solution due to metal impurities is suppressed, the capacitance is further improved, and the electric resistance is further reduced.

  The alkali metal content of the activated carbon is 500 ppm or less, preferably 200 ppm or less, more preferably 50 ppm or less. If the alkali metal content is within the above range, for example, when used as an electrode material, the decomposition of the electrolyte solution due to the alkali metal component is suppressed, so that the electric double layer capacitor exhibiting high capacitance and low resistance Is obtained.

BET specific surface area of the activated carbon is preferably not less than 1600 m ² / g, more preferably 1700 m ² / g or more, still more preferably 1800 m ² / g or more, is preferably from 3000 m ² / g, more preferably 2500 m ² / g Hereinafter, it is more preferably 2200 m ² / g or less. When the BET specific surface area is less than 1600 m ² / g, the adsorption ability of the activated carbon becomes low. Therefore, for example, when activated carbon is used for the electrode for an electric double layer capacitor, a sufficient capacitance per unit mass (F / g) cannot be obtained. On the other hand, if the BET specific surface area exceeds 3000 m ² / g, the density of the activated carbon is excessively lowered. Therefore, for example, when activated carbon is used for an electrode for an electric double layer capacitor, the capacitance per volume (F / cm ³ ) is lowered.

Pore volume of the activated carbon is preferably at least 0.7 cm ³ / g, more preferably 0.9 cm ³ / g or more, more preferably 1.2 cm ³ / g or more, 3.0 cm ³ / g or less Preferably, it is 2.5 cm ³ / g or less, more preferably 2.0 cm ³ / g or less.

  The average pore diameter of the activated carbon is preferably 2.0 nm or more, more preferably 2.1 nm or more, still more preferably 2.2 nm or more, preferably 3.0 nm or less, more preferably 2.6 nm or less, still more preferably 2.4 nm or less. When the average pore diameter is within the above range, the adsorbed material easily enters and exits the activated carbon. Therefore, for example, when used as an electrode for an electric double layer capacitor, rapid charge / discharge characteristics are improved.

  Activated carbon obtained by the production method of the present invention can be used as an electrode material for an electric double layer capacitor, and an electrode for an electric double layer capacitor or an electric double layer capacitor can be produced using the electrode material. is there.

  As an electrode for an electric double layer capacitor, for example, knead activated carbon, a conductivity imparting agent, and a binder, further add a solvent to prepare a paste, and after applying this paste to a current collector plate such as an aluminum foil, What removed the solvent by drying is mentioned.

  As the binder used for the electrode for the electric double layer capacitor, fluorine-based polymer compounds such as polytetrafluoroethylene and polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber, petroleum pitch, phenol resin and the like can be used. As the conductivity-imparting agent, acetylene black, ketjen black, or the like can be used.

  Generally, an electric double layer capacitor has a structure in which an electrode, an electrolytic solution, and a separator are main components, and a separator is disposed between a pair of electrodes. Examples of the electrolytic solution include an electrolytic solution in which an amidine salt is dissolved in an organic solvent such as propylene carbonate, ethylene carbonate, and methyl ethyl carbonate; an electrolytic solution in which a quaternary ammonium salt of perchloric acid is dissolved; quaternary ammonium or lithium An electrolytic solution in which an alkali metal boron tetrafluoride salt or phosphorous hexafluoride salt such as an electrolyte is dissolved; an electrolytic solution in which a quaternary phosphonium salt is dissolved may be mentioned. Moreover, as said separator, the nonwoven fabric, cloth, and microporous film which have polyolefin, such as a cellulose, glass fiber, or polyethylene and a polypropylene, as a main component are mentioned, for example.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.

Content of ash, metal impurities, etc. 1 g of the activated carbon sample was put in a magnetic crucible, heated at 815 ° C. for 2 hours to be ashed, the amount of ash was measured, and the ash content in the activated carbon was calculated. Moreover, the impurity in ash was qualitatively and quantified using the fluorescent X-ray-analysis apparatus (Rigaku company make, "ZSX 100e").

Measuring method of specific surface area, total pore volume and average pore diameter After 0.2 g of activated carbon was heated under vacuum at 150 ° C., a nitrogen adsorption device (“ASAP (registered trademark) -2400” manufactured by Micromeritics) was used. The adsorption isotherm was determined and the specific surface area and total pore volume were calculated by the BET method. Further, assuming that the shape of the pores formed in the activated carbon is cylindrical, the average pore size was calculated by the following formula (1) based on the pore volume and specific surface area in the pore size range of 1.0 nm to 30 nm.

Electric double layer capacitor performance evaluation Capacitance Charge / discharge device (Etamoto Kasei Co., Ltd., “ETAC (registered trademark) Ver. 4.4”) charge / discharge terminal is connected to current collector plate of electric double layer capacitor, The battery was charged with a constant current of 40 mA until the voltage between the plates reached 2.5 V, and then charged with a constant voltage of 2.5 V for 30 minutes. After charging, the electric double layer capacitor was discharged with a constant current (discharge current 10 mA). At this time, the discharge times t1 and t2 required until the voltage between the current collector plates became V1 and V2 were measured, and the capacitance was obtained using the following formula (2). The mass-based capacitance (F / g) is calculated by dividing the obtained capacitance by the mass of activated carbon in the electrode material layer in the capacitor electrode, and divided by the total volume of the electrode material layer in the capacitor electrode. Thus, a volume-based capacitance (F / cm ³ ) was calculated. Moreover, resistance was calculated | required using following formula (3). The capacitance and resistance were measured at 25 ° C. and −30 ° C.

I: 10 (mA)
t1: Discharge time required for the electric double layer capacitor voltage to reach V1 (sec)
t2: Discharge time (sec) required for the electric double layer capacitor voltage to reach V2
V1: 2.0 (V)
V2: 1.0 (V)
V0: Voltage immediately after the start of discharge

1. Production and production example 1 of activated carbon
100 g of carbonized paper phenol resin laminate was put into a rotary kiln and heated to 900 ° C. under nitrogen flow (1 L / min) (heating rate: 10 ° C./min). After reaching 900 ° C., steam (steam partial pressure: 71.2 kPa) was supplied into the rotary kiln together with nitrogen, and steam activation treatment was performed for 3 hours 30 minutes. 50 g of the sample after the steam activation treatment was immersed in 2 L of a potassium hydroxide (KOH) aqueous solution having a concentration of 5 mass% and a temperature of 60 ° C. for 1 hour, and then vacuum filtered. The filtered sample was washed with warm water at 60 ° C. and vacuum filtered, then boiled in 2 L of a hydrochloric acid (HCl) aqueous solution having a concentration of 5.25 mass% for 1 hour, and then vacuum filtered. The sample after filtration was washed with 60 ° C. warm water and vacuum filtered to produce activated carbon.

Production Example 2
Activated carbon was produced in the same manner as in Production Example 1 except that the concentration of the aqueous potassium hydroxide solution used for washing was changed to 10% by mass.

Production Example 3
Activated carbon was produced in the same manner as in Production Example 1 except that the concentration of the aqueous potassium hydroxide solution used for washing was changed to 20% by mass.

Production Example 4
A steam activation treatment was performed in the same manner as in Production Example 1. 50 g of the sample after the steam activation treatment was immersed in 2 L of a hydrochloric acid (HCl) aqueous solution having a concentration of 5.25% by mass and a temperature of 60 ° C. for 1 hour, and then vacuum filtered. The filtered sample was washed with warm water at 60 ° C. and vacuum filtered, then boiled in 2 L of a potassium hydroxide (KOH) aqueous solution having a concentration of 20% by mass for 1 hour, and then vacuum filtered. The sample after filtration was washed with 60 ° C. warm water and vacuum filtered to produce activated carbon.

Production Example 5
100 g of carbonized paper phenol resin laminate was put into a rotary kiln and heated to 900 ° C. under nitrogen flow (1 L / min) (heating rate: 10 ° C./min). After reaching 900 ° C., water vapor (water vapor partial pressure: 71.2 kPa) was supplied into the rotary kiln together with nitrogen, and steam activation treatment was performed for 3 hours 30 minutes to produce activated carbon.

Production Example 6
100 g of carbonized paper phenol resin laminate was put into a rotary kiln and heated to 900 ° C. under nitrogen flow (1 L / min) (heating rate: 10 ° C./min). After reaching 900 ° C., steam (steam partial pressure: 71.2 kPa) was supplied into the rotary kiln together with nitrogen, and steam activation treatment was performed for 3 hours 30 minutes. 50 g of the sample after the steam activation treatment was immersed in 2 L of a hydrochloric acid (HCl) aqueous solution having a concentration of 5.25% by mass and a temperature of 60 ° C. for 1 hour, and then vacuum filtered. The sample after filtration was washed with 60 ° C. warm water and vacuum filtered to produce activated carbon.

Production Example 7
100 g of carbonized paper phenol resin laminate was put into a rotary kiln and heated to 900 ° C. under nitrogen flow (1 L / min) (heating rate: 10 ° C./min). After reaching 900 ° C., steam (steam partial pressure: 71.2 kPa) was supplied into the rotary kiln together with nitrogen, and steam activation treatment was performed for 3 hours 30 minutes. A 50 g sample after the steam activation treatment was immersed in 2 L of a potassium hydroxide (KOH) aqueous solution having a concentration of 20 mass% and a temperature of 60 ° C. for 1 hour, and then vacuum filtered. The sample after filtration was washed with 60 ° C. warm water and vacuum filtered to produce activated carbon.

2. Production of Electric Double Layer Capacitor An electric double layer capacitor was produced using the activated carbon obtained in Production Examples 1-7. Specifically, polytetrafluoroethylene (PTFE) powder and acetylene black are mixed with activated carbon so as to be activated carbon: PTFE: acetylene black = 8: 1: 1 (mass ratio), until a paste is obtained. Kneaded. Subsequently, it grind | pulverized with the mini blender and sieved with the stainless steel sieve of 500 micrometers, and the particle size was arrange | equalized. Next, using a metal mold with a diameter of 2.54 cm, the amount of charge was adjusted so that the thickness after pressing was 0.5 mm, and press molding was performed at a pressure of 50.4 MPa to produce a capacitor electrode.

  The obtained capacitor electrode was dried under vacuum conditions at 200 ° C. for 1 hour, and then an electrolyte (1M tetraethylammonium tetrafluoroborate propylene carbonate solution) was used as an electrode in a glove box in which nitrogen gas was circulated. Vacuum impregnated. Using this electrode, an electric double layer capacitor was assembled as shown in FIG. The electric double layer capacitor shown in FIG. 1 has a separator (Celgard, “Celgard (registered trademark) # 3501”) 1 impregnated with the electrolytic solution sandwiched between the capacitor electrodes 2, and the electrodes are surrounded by an O-ring 3. Then, it was further sandwiched between aluminum plates 4 as current collector plates.

  The evaluation results of the activated carbon obtained in Production Examples 1 to 7 are shown in Tables 1 and 2. The evaluation results of the electric double layer capacitor are shown in Table 1.

As shown in Table 1, in Production Examples 1 to 4 in which washing was performed with an alkaline solution and an acidic solution, the silicon content in the obtained activated carbon was reduced, and in the electric double layer capacitor evaluation, the capacitance was It can be seen that the resistance is high and the resistance is low. Among these, the ash content (silicon content) in the obtained activated carbon is reduced in Production Examples 1 to 3, which were washed with an alkaline solution and then washed with an acidic solution.
In Production Example 6 in which only the washing with the acidic solution was performed, the content of alkali metal and alkaline earth metal in the obtained activated carbon was reduced as compared with Production Example 5, but the silicon content was not much removed. Not. In Production Example 7 in which only the washing with the alkaline solution was performed, the silicon content in the obtained activated carbon was removed by about half compared to Production Example 5, but it was not sufficiently removed yet and was not less than 5000 ppm. It was a high value.

  Activated carbon obtained by the production method of the present invention can be used as an electrode material for an electric double layer capacitor, and an electrode for an electric double layer capacitor or an electric double layer capacitor can be produced using the electrode material. is there.

1: Separator, 2: Electrode for capacitor, 3: O-ring, 4: Aluminum plate, 5: Polytetrafluoroethylene plate, 6: Stainless steel plate

Claims (5)

The activated product obtained by steam activation of the carbonized paper phenol resin laminate before activation, the alkaline solution having an alkali metal hydroxide concentration of 5 to 30% by mass and the acid component having an acid component concentration of 3 to 20% by mass A method for producing activated carbon having an average pore diameter of 2.2 nm or more , wherein the solution is washed in this order or in the reverse order.   The method for producing activated carbon according to claim 1, wherein the activation product is washed with an alkaline solution and then washed with an acidic solution. The silicon content is 200 ppm to 3000 ppm, the specific surface area is 1600 m ² / g or more, and the average pore diameter is 2. Activated carbon characterized by being 2 nm or more. 4. An electrode for an electric double layer capacitor, wherein the activated carbon according to claim 3 is used as an electrode material. An electric double layer capacitor comprising the electrode according to claim 4 .