JP5882191B2 - Activated carbon and method for producing the same - Google Patents

Description

  The present invention relates to activated carbon and a method for producing the same, and more particularly, to activated carbon having an excellent initial adsorption rate for an adsorbent and a method for producing the activated carbon.

  Activated carbon has innumerable pores on its surface and is widely used as an adsorbent for removing adsorbed substances such as harmful substances in gases or liquids by utilizing its adsorption ability. In recent years, activated carbon has been used in various fields such as an electronic material such as a polarizable electrode material for an electric double layer capacitor.

  The pores of the activated carbon are classified into macropores (diameter 50 nm or more), mesopores (diameter 2 nm or more and less than 50 nm), and micropores (diameter 2 nm or less) according to the pore diameter (IUPAC (International Union of Pure). and Applied Chemistry). Micropores are adsorption sites that mainly function as adsorption sites for adsorbents, and mesopores and macropores function as a route for transporting gases and liquids containing adsorbates to the micropores, affecting the adsorption rate. It is known to do.

  Since the specific surface area increases as the number of micropores increases, activated carbon with developed micropores such as coconut shell activated carbon tends to have higher equilibrium adsorption performance (equilibrium adsorption amount). However, in the case of activated carbon in which mesopores and macropores are not sufficiently developed even if micropores are developed, the moving speed of the adsorbed material into the pores becomes slow.

  As means for solving such a problem, various activated carbons having a controlled proportion of pores have been proposed.

For example, in Patent Document 1, coal is used as a raw material, and the pore volume with a pore diameter of 30 nm or more is 0.2 to 0.6 mL / g, of which the proportion of the pore volume with a pore diameter of 1 μm or less is 60% or more, the BET ratio A spherical activated carbon having a surface area of 800 to 2000 m ² / g and an angle of repose of 30 ° or less is disclosed.

  Patent Document 2 discloses that the integrated pore volume in the range of average pore diameter of 3000 to 100,000 nm measured by mercury porosimetry is 6.5 mL / dL or more, and the equilibrium adsorption amount at an n-butane volume concentration of 2000 ppm is 0.16 g / dL. The adsorbent which is the above is disclosed.

JP 2006-83052 A International Publication No. 2009/031467

  Conventionally proposed activated carbon with improved adsorption rate improves the characteristics of activated carbon by granulating or molding a plurality of activated carbon particles (primary particles). For example, when a plurality of activated carbon particles are granulated or molded, voids are formed between the primary particles of the activated carbon (inside the secondary particles), and these voids function as a transport path, improving the adsorption rate. However, activated carbon having an excellent adsorption rate without granulation or molding has been demanded from the viewpoint of manufacturing cost reduction. In recent years, there has been a demand for improvement in the initial adsorption rate immediately after the start of adsorption as part of improvement in adsorption efficiency of the adsorbent and charge / discharge characteristics of the electrode material for electric double layer capacitors.

  This invention is made paying attention to the above situations, and is providing the activated carbon excellent in the initial adsorption rate of activated carbon, and its manufacturing method.

The activated carbon of the present invention capable of solving the above problems shows a distribution peak in the region of pore diameter of 0.1 to 3 μm when the pore diameter distribution of primary particles is measured, and the total of pore diameters of 0.05 to 5 μm. The volume is 0.4 mL / g or more.

Moreover, it is also a preferable embodiment that the total volume of pore diameters of 0.05 to 5 μm per specific surface area is 0.2 μL / m ² or more.

It is also a preferred embodiment that the specific surface area is 800 m ² / g or more and the total pore volume is 0.4 mL / g or more.

  Moreover, it is desirable that the activated carbon of the present invention be obtained by subjecting a solid extraction residue produced when coal is extracted with an organic solvent having a temperature of 200 ° C. or more to alkali activation treatment.

  Furthermore, it is also preferable that the amount of ash in the solid residue is 5% by mass or more.

  The present invention also includes an adsorbent using the activated carbon and an electrode material for an electric double layer capacitor using the activated carbon.

  Moreover, the manufacturing method of activated carbon of this invention has a summary in having the process of carrying out the extraction process of coal with the organic solvent with a temperature of 200 degreeC or more, and the process of carrying out the alkali activation process of the solid extraction residue remaining by this extraction process.

  According to the activated carbon of the present invention, since the pore diameter shows a specific distribution, the initial adsorption rate is excellent while maintaining the primary particles. Moreover, according to the manufacturing method of this invention, the said activated carbon excellent in the initial stage adsorption rate can be provided. The activated carbon of the present invention is lower in production cost than conventional ones, and is suitable as an adsorbent such as an adsorbent for water purification and an adsorbent for wastewater purification, and an electrode material for electric double layer capacitors.

FIG. 1 is a graph showing the pore volume and pore size distribution of activated carbon measured by mercury porosimetry. FIG. 2 is a graph showing the adsorption rate of activated carbon (relationship between equilibrium arrival rate and elapsed time). FIG. 3 is a graph showing the adsorption rate of activated carbon (relationship between the equilibrium arrival rate (5 minutes) and the total volume (mL / g) of pore diameters of 0.05 to 5 μm). FIG. 4 is a graph showing the adsorption rate of activated carbon (relationship between the equilibrium arrival rate (5 minutes) and the total volume (μL / m ² ) of pore diameters of 0.05 to 5 μm per specific surface area). It is explanatory drawing which illustrates the apparatus and process which manufacture the solid extraction residue used by this invention.

  The present inventors show a distribution peak in a region having a pore diameter of 0.1 to 3 μm and primary particles of activated carbon having a total volume of pores of 0.05 to 5 μm of 0.4 mL / g or more. It has been found that the diffusion and movement speed of adsorbate is increased, the initial adsorption speed is improved, and the adsorption sites (micropores) existing in the deep pores can be fully utilized. Therefore, if the activated carbon of the present invention is used as an adsorbent, the initial adsorption rate can be improved. In addition, when the activated carbon of the present invention is used as an electrode material for an electric double layer capacitor, an improvement in rapid charge / discharge characteristics can be expected.

  In the present invention, the initial adsorption rate is the equilibrium arrival rate after 5 minutes from the start of adsorption (0 minutes), and the higher the equilibrium arrival rate, the higher the initial adsorption rate. The equilibrium achievement rate is a value measured based on the adsorption rate test described in the examples. The equilibrium achievement rate is preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, still more preferably 85% or more, and most preferably 90% or more.

  In the present invention, the “distribution peak” means a pore size distribution curve (vertical axis: pore volume (mL / g), horizontal axis: fine) obtained when the pore size distribution of primary particles is measured according to the mercury intrusion method. The maximum value on the pore diameter (μm)).

  Hereinafter, the activated carbon of the present invention will be specifically described.

  The reason why the peak position of the distribution when the pore diameter distribution of the primary particles is measured in the present invention is limited to the range of the pore diameter of 0.1 μm to 3 μm is that the initial adsorption is that the pore diameter at the peak position is 0.1 μm or more. It is effective for speed improvement. On the other hand, if the pore diameter at the peak position is too large, the distance between adjacent pores may be narrowed, which may reduce the strength of the particles, and the number of pores may decrease, affecting the adsorption capacity. The upper limit was 3 μm. The position of the distribution peak is preferably a pore diameter of 0.3 μm or more, more preferably 0.5 μm or more, preferably 2.5 μm or less, more preferably 2.0 μm or less.

  Furthermore, in the present invention, from the viewpoint of improving the initial adsorption rate, in addition to the above distribution peak, the total volume in the range of the pore diameter of the primary particles of 0.05 to 5 μm needs to be 0.4 mL / g or more. . Since the initial adsorption rate is improved when the total volume is increased, it is preferably 0.45 mL / g or more, more preferably 0.47 mL / g or more, and further preferably 0.50 mL / g or more. On the other hand, if the total volume becomes too large, the strength may decrease, so that it is preferably 2.0 mL / g or less, more preferably 1.5 mL / g or less.

  The reason why the total volume range was set to a pore diameter of 0.05 to 5 μm was determined in consideration of the balance between the initial adsorption rate and the strength of the activated carbon, and if the predetermined total volume is satisfied within this range, The effect of improving the initial adsorption rate can be achieved.

Furthermore, in this invention, it is preferable that the total volume of the said pore diameter 0.05-5 micrometers per specific surface area is 0.2 microliters / m < ² > or more. If the total volume per specific surface area is 0.2 μL / m ² or more, the adsorption rate improvement effect can be further enhanced. More preferably 0.25 [mu] L / m ² or more, still more preferably 0.30μL / m ² or more. On the other hand, if the total volume per specific surface area becomes too large, the specific surface area of the activated carbon may be reduced and the adsorption capacity and adsorption rate may be lowered, so that it is preferably 1.0 μL / m ² or less, more preferably 0.8. 5 μL / m ² or less.

The specific surface area of the primary particles is not particularly limited, but if the specific surface area is too small, the adsorption capacity of activated carbon is lowered, and when used for an electric double layer capacitor electrode, the capacitance per mass (F / g ) May be low, and is preferably 800 m ² / g or more, more preferably 1200 m ² / g or more. On the other hand, if the specific surface area becomes too large, the density may decrease and the strength of the particles may be lowered. Therefore, the specific surface area is preferably 4000 m ² / g or less, more preferably 3000 m ² / g or less.

  The total pore volume of the primary particles is not particularly limited, but from the viewpoint of improving the adsorption performance (adsorption amount) of activated carbon, in addition to the above-mentioned peak distribution of pore diameter and the total volume, the equilibrium adsorption performance is improved. It is desirable to have well-balanced micropores that affect and mesopores that affect the adsorption rate. Therefore, the pore volume (total pore volume) of the activated carbon in consideration of these is preferably 0.4 mL / g or more, more preferably 0.5 mL / g or more, and further preferably 0.6 mL / g or more. is there. On the other hand, if the total pore volume becomes too large, the specific surface area decreases, so that it is preferably 2.5 mL / g or less, more preferably 2.0 mL / g or less.

  The activated carbon of the present invention having the above characteristics is obtained by subjecting a solid extraction residue (preferably an ash content of 5% or more) generated when coal is extracted with an organic solvent having a temperature of 200 ° C. or higher to alkali activation treatment as described later. It is desirable. Extraction treatment of coal at a predetermined temperature promotes the formation of macropores, and further promotes the formation of macropores in the alkali activation step, so that the activated carbon of the present invention having excellent initial adsorption rate can be easily obtained. Can be manufactured.

  In the present invention, the type of coal used as a raw material for activated carbon is not particularly limited, and may be any of high-grade coal such as anthracite and bituminous coal; and low-grade coal such as sub-bituminous coal, lignite, and peat.

  The average particle diameter of coal is not particularly limited, but is preferably finely divided from the viewpoint of increasing extraction efficiency with an organic solvent. For example, the average particle diameter is preferably 10 mm or less, more preferably 5 mm or less. It is desirable that it is pulverized. Further, by reducing the particle diameter, the specific surface area, total pore volume, and total volume (total volume per mass, total volume per specific surface area) at a pore diameter of 0.05 to 5 μm can be increased.

  A solid extraction residue can be obtained by extracting coal with an organic solvent. The process of extracting coal with an organic solvent is a process of eluting at least a part of an extraction component (organic solvent-soluble component) contained in coal into an organic solvent.

  When coal is extracted with an organic solvent, a solvent-soluble organic component contained in the coal is eluted into the organic solvent. In the present invention, the solvent-soluble organic substance is extracted at a temperature of 200 ° C. or more. It has been found that the elution ratio of components can be increased and a solid extraction residue containing more pores can be obtained. By performing the extraction treatment at 200 ° C. or more in this way, numerous holes (pores) from which the extraction components are removed are formed on the surface of the solid extraction residue after the extraction treatment.

  The organic solvent is not particularly limited as long as it can dissolve extraction components (pyrene, naphthacene, perylene, etc.) contained in coal. For example, heterocyclic compounds such as N-methyl-2-pyrrolidone, quinoline, pyridine, tetrahydrofuran, pyrazine, quinoxaline, acridine; aromatic carbonization such as benzene, toluene, xylene, mesitylene, naphthalene, anthracene, pyrene, chrysene, perylene Hydrogen; aliphatic hydrocarbons such as hexane, heptane and cyclohexane; halogenated aliphatic hydrocarbons such as chloroform and dichloroethane; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; alcohols such as methanol, ethanol and propanol; Can be mentioned. Among these, as organic solvents suitable for efficient elution of extracts such as pyrene, naphthalene, and perylene, heterocyclic compounds and aromatic hydrocarbons are preferable, and bicyclic heterocyclic compounds, bicyclic rings are more preferable. And aromatic hydrocarbons such as quinoxaline, acridine, naphthalene, anthracene, pyrene, chrysene, and perylene. These organic solvents may have an appropriate substituent (for example, an alkyl group such as a methyl group).

  These organic solvents may be used alone or in combination of two or more. Moreover, you may make water contain an organic solvent to such an extent that the effect of this invention is not impaired.

  The method of extraction processing is not particularly limited as long as it can elute extracted components from coal, and various known extraction methods can be adopted. For example, a method in which coal is immersed in an organic solvent and subjected to ultrasonic treatment; a method in which coal is immersed in an organic solvent and stirred; a Soxhlet extraction method, and the like can be given. Among these, the method of immersing coal in an organic solvent and stirring is preferable because the extraction component (organic solvent-soluble component) can be more efficiently eluted in a predetermined temperature range.

  The following process is exemplified as a method for obtaining a solid extraction residue by a method in which coal is immersed in an organic solvent and stirred. That is, coal is mixed with an organic solvent to prepare a slurry, and the resulting slurry is heated and aged to extract soluble components in the organic solvent, and then the slurry is concentrated by concentrating the supernatant and solid phase components. After separation into a liquid, a solid extract residue is obtained by drying the filtrate obtained by filtering the solid phase component concentrate.

  Such a process is used, for example, in the production of demineralized coal (also referred to as hypercoal or ashless coal). In the present invention, coal is obtained during the process of producing demineralized coal by an extraction method using an organic solvent. The solid extraction residue obtained can also be used.

  The above process will be described in more detail with reference to FIG. According to FIG. 5, in the tank 1, coal and an organic solvent are mixed and a slurry is produced | generated. The obtained slurry is supplied to the extraction tank 4 where the pump 2 performs the extraction process. At that time, the slurry is heated to a predetermined temperature by the preheater 3. In the extraction tank 4, the soluble component is extracted into an organic solvent while stirring the slurry using the stirrer 10 (step of extracting coal with an organic solvent). Next, the slurry in the extraction tank 4 is supplied to the gravity settling tank 5. In the gravity settling tank 5, gravity settling is performed to settle the solid phase component (arrow 11), and the slurry is separated into a supernatant liquid and a liquid in which the solid phase component is concentrated. The supernatant liquid is supplied to the filter unit 8 and filtered through the filter member 7, and the obtained filtrate is recovered in a supernatant liquid receiver 9 that recovers the supernatant liquid. Then, ashless coal (hypercoal) is obtained by evaporating and removing the organic solvent from the collected supernatant. The solid phase component concentrate that has settled in the gravity sedimentation tank 5 is collected in the solid phase component concentrate receiver 6 and stirred by the stirrer 13. A solid phase residue is obtained by filtering the solid phase component concentrate through a filter member (not shown) and drying the filtrate obtained by filtration.

  In the process of extracting coal with an organic solvent, the amount of the organic solvent used is not particularly limited, but the mass ratio of the coal to the organic solvent (organic solvent / coal) is set to 2 or more from the viewpoint of increasing the extraction efficiency. More preferably, it is 3 or more, More preferably, it is 4 or more, It is preferable to set it as 40 or less, More preferably, it is 30 or less, More preferably, it is 20 or less.

  As a method for extracting a soluble component in an organic solvent by heating and aging the slurry, for example, the slurry is held at 200 ° C. to 420 ° C. for 5 minutes to 120 minutes (preferably 10 minutes to 30 minutes), and in coal The aspect which solubilizes this soluble component is mentioned. Since the pore diameter and pore volume can be increased by appropriately controlling the temperature, it is an important condition in the production of the primary particles of the activated carbon of the present invention. When the holding temperature is lower than 200 ° C., it is insufficient to weaken the bonds between the molecules constituting the coal, the proportion of soluble components that can be extracted from the coal is reduced, and the fineness formed when the holding temperature is low. The pore diameter of the pores cannot be made sufficiently large, and a desired distribution peak and pore volume cannot be obtained. On the other hand, when the holding temperature is higher than 420 ° C., the pyrolysis reaction of coal becomes active and recombination of the generated pyrolysis radicals occurs, so that the ratio of the soluble components that are extracted may also decrease. Further, when the holding temperature is high, the pore diameter formed becomes too large to obtain the desired activated carbon, and the surface area and strength are reduced. The holding temperature during the extraction treatment is preferably 250 ° C. or higher, more preferably 300 ° C. or higher, preferably 400 ° C. or lower, more preferably 380 ° C. or lower.

  After the elution treatment, for example, only the solid extraction residue can be taken out by filtration. The solid extraction residue collected by filtration is preferably dried at 20 ° C. to 300 ° C. for 0.5 hours to 24 hours in a nitrogen atmosphere or under vacuum.

  Subsequently, an alkali activation treatment is applied to the solid extraction residue. The step of subjecting the solid extraction residue to alkali activation is generally a treatment for forming pores on the surface of the solid extraction residue and mainly increasing the specific surface area and pore volume (mainly micropores). By subjecting the solid extraction residue to an alkali activation treatment, it is possible to further promote the formation of activated carbon having the desired distribution peak and pore volume. That is, the solid extraction residue is mainly a coal component containing impurity components such as ash remaining without being dissolved in an organic solvent (for example, silicic acid, alumina, iron oxide, lime, magnesia, alkali metal, etc.) and ash coal containing the ash. In particular, a large amount of Si is contained as an impurity component. When such a solid extraction residue is subjected to an alkali activation treatment, impurity components such as Si contained in the solid extraction residue can be eluted, and the resulting activated carbon has numerous pores (holes) from which the impurity component has been removed. Formed. The pores formed at this time, together with the pores formed during the extraction process, contribute to the desired distribution peak and pore volume according to the present invention. Activated carbon is obtained.

  In addition, the said effect by an activation process is a specific effect acquired when performing an alkali activation process, Comprising: It cannot obtain by other activation processing methods, such as a gas activation process and a water vapor activation process. For example, when a gas activation treatment or a steam activation treatment is performed on the solid extraction residue, only the impurity component cannot be selectively eluted, and the activation proceeds while eroding the solid extraction residue. Activated carbon having a distribution peak and pore volume cannot be obtained.

  The alkali activation treatment can be activated by mixing a solid extraction residue and a drug (for example, an alkali activation agent) and heating them. The activation treatment conditions are not particularly limited, but examples include the following conditions.

  As the alkali activator, an alkali metal compound is preferable. Examples of the alkali metal compound include hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide; carbonates such as sodium carbonate, potassium carbonate and lithium carbonate. These alkali activators may be used alone or in combination of two or more. Of these, potassium hydroxide is preferred.

  The mass ratio between the solid extraction residue and the alkali activator (alkali activator / solid extraction residue) is not particularly limited as long as it is appropriately set so that the above-described activation effect and impurity elution effect are obtained to a desired extent. When there are too few alkali activators, the remaining ash cannot fully be removed and the said effect may be low. Moreover, when there are too many alkali activators, activated carbon will become embrittled and will cause the fall of intensity | strength. The mass ratio between the solid extraction residue and the alkali activator (alkali activator / solid extraction residue) is preferably 0.5 or more, more preferably 1.5 or more, and still more preferably 2.0 or more. It is preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3.5 or less.

  Moreover, when adding an alkali activator, in order to fully mix with a solid extraction residue, you may use an alkali activator as aqueous solution. The amount of water used at this time is preferably 0.05 times by mass to 10 times by mass of the alkali activator. In addition, when using an alkali activator as an aqueous solution, before performing heating for the activation treatment, heating at a temperature lower than the heating temperature in the activation treatment is performed to prevent bumping of moisture derived from the alkaline activator aqueous solution. It is preferable to remove moisture by performing treatment.

  The heating temperature for performing the activation treatment is preferably 600 ° C. or higher, more preferably 650 ° C. or higher, preferably 950 ° C. or lower, more preferably 900 ° C. or lower. In addition, the heating time in performing the activation treatment is preferably 0.1 hour or longer, more preferably 1.5 hours or longer, 3.5 hours or shorter, more preferably 3 hours or shorter. The atmosphere during heating is preferably an inert gas atmosphere such as argon, helium, or nitrogen.

  After the activation treatment, washing treatment, heat treatment, pulverization treatment, or the like may be performed as necessary.

  The cleaning process is a process of cleaning the activated carbon after the activation process, and may be dried if necessary. Since the alkali metal hydroxide used as an alkali activator adheres to the surface of the activated carbon after the activation treatment, the activated carbon is washed to remove such deposits. Examples of the method for washing activated carbon include water washing and acid washing.

  The washing method is not particularly limited, but for example, it is preferably performed by adding activated carbon to water, stirring and dispersing as necessary, and then filtering. Stirring and dispersion can be performed by mechanical stirring, gas blowing, ultrasonic irradiation, and heating boiling. The water temperature at the time of water washing is not specifically limited, For example, 30 degreeC or more may be sufficient. Moreover, stirring and dispersion time are not particularly limited, and for example, it is preferably performed for 0.5 hour or longer.

  The acid cleaning is cleaning performed using a cleaning liquid containing an inorganic acid, an organic acid, or the like. The solvent for the cleaning liquid is not particularly limited, but is usually water. By performing the acid cleaning, the alkali metal hydroxide used as the alkali activator can be efficiently removed.

  Examples of inorganic acids include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and carbonic acid. These inorganic acids may be used alone or in combination of two or more. When the inorganic acid is used, the concentration of the inorganic acid in the cleaning liquid is preferably 0.5 mol / L or more, more preferably 1.0 mol / L or more, and preferably 3.5 mol / L or less, more preferably 3. 0 mol / L or less. The method of acid cleaning using an inorganic acid is not particularly limited. For example, activated carbon and a cleaning liquid containing an inorganic acid are mixed and stirred at a temperature of 50 ° C. to 100 ° C. for 30 minutes to 120 minutes. Is preferably performed.

  Examples of the organic acid include formic acid, oxalic acid, malonic acid, succinic acid, acetic acid, propionic acid, and the like. These organic acids may be used alone or in combination of two or more. The concentration of the organic acid in the cleaning liquid containing the organic acid is preferably 1 vol% or more, more preferably 2 vol% or more, still more preferably 5 vol% or more, preferably 100 vol% or less, more preferably 80 vol% or less, More preferably, it is 60 vol% or less. By setting the concentration of the organic acid to 1 vol% or more, the effect of removing the metal component by the organic acid can be obtained. The method of acid cleaning using an organic acid is, for example, mixing activated carbon and a cleaning solution containing an organic acid, and stirring the resulting mixture at a temperature of 20 ° C. to 80 ° C. for 1 minute to 120 minutes. Is preferably performed. The activated carbon after washing is preferably dried at 50 to 120 ° C. for 0.5 to 2.0 hours.

  In the manufacturing method of this invention, it is preferable to perform acid washing and water washing as a washing | cleaning process, More preferably, after performing acid washing, it is the aspect which performs water washing several times.

  It is also preferable to heat-treat the activated carbon after the activation treatment or after the washing treatment in an inert gas atmosphere (heat treatment step). By performing heat treatment on the activated carbon, the amount of functional groups on the surface of the activated carbon can be adjusted.

  Examples of the heat treatment include an aspect in which the activated carbon immediately after the activation treatment is heat-treated in an inert gas atmosphere; an embodiment in which the activated carbon after the activation treatment is acid-washed and / or washed with water and then heat-treated in an inert gas atmosphere. Can do. As said inert gas, argon, nitrogen, helium etc. can be used, for example. The heat treatment temperature is not particularly limited, but is preferably 400 ° C. or higher and 1000 ° C. or lower.

  Furthermore, you may grind | pulverize as needed, in order to adjust the particle size of activated carbon (grinding process process). The method for pulverizing the activated carbon is not particularly limited, and may be performed using a Henschel mixer, a jet mill, a disk mill, a ball mill, a bead mill, or the like. In addition, the average particle diameter of activated carbon is not specifically limited, What is necessary is just to prepare suitably according to a use. For example, when used as an adsorbent for water purification, considering the balance between adsorption performance and pressure loss during water flow, it is preferably about 50 to 500 μm. In addition, when used as an electrode material for an electric double layer capacitor, it is preferable that the thickness is approximately 1 μm to 10 μm in consideration of handling properties such as binding property to a current collector plate.

  The activated carbon obtained by the production method of the present invention can be used as an activated carbon for adsorption in various applications such as deodorization and harmful substance removal. For example, a filler for gas adsorption, a filler for a water purifier (filter material, adsorbent). It is suitable as an adsorbing material. Further, it 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.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

(Production of solid extraction residue)
A solid extraction residue was produced by the following method.

  Australian bituminous coal A (raw coal A: ash 17.0%) or Australian bituminous coal B (raw coal B: ash 12.8%) was used as the raw material coal (carbonaceous material).

  A slurry was prepared by mixing 4 kg (20 kg) of a solvent (1-methylnaphthalene (manufactured by Nippon Steel Chemical Co., Ltd.)) with 5 kg of this raw material coal. This slurry was pressurized (1.2 MPa) under a nitrogen atmosphere and extracted in a batch-type autoclave with an internal volume of 30 L at 370 ° C. for 1 hour. This slurry is separated into a supernatant and a solid concentrate in a gravity sedimentation tank maintained at the same temperature and pressure, and the solvent is separated and recovered from the solid concentrate by a distillation method to obtain a solid extraction residue (raw material coal A Solid extraction residue X or raw coal B solid extraction residue Y).

(Manufacture of activated carbon)
Production Example 1
To the solid extraction residue X30g of the above-mentioned Australian bituminous coal (raw coal A) having a particle size adjusted to 1 to 2 mm, the mass ratio (activator / solid extraction residue) is 2.5 times (75 g) of hydroxylation as an activator. After mixing potassium (alkaline activator), the mixture was heated at 800 ° C. for 2 hours in a nitrogen atmosphere to perform alkali activation treatment to obtain a porous carbon material.

  The obtained porous carbon material was washed with water (temperature: 60 ° C.) and then washed with hydrochloric acid (5.25 mass% hydrochloric acid) to obtain activated carbon from which metal impurities and the like were removed. Thereafter, the activated carbon was put into a tube furnace (KTF055N manufactured by Koyo Thermo Systems Co., Ltd.) and the temperature in the furnace was raised to 1000 ° C. under a nitrogen flow (0.4 L / min) (heating rate: 10 ° C./min). Holding at 2 ° C. for 2 hours, activated carbon A was obtained.

Production Example 2
To the solid extraction residue X30g of the above-mentioned Australian bituminous coal (raw coal A) adjusted to a particle size of 2mm or less, 1.0 times (30g) potassium hydroxide in mass ratio (activator / solid extraction residue) as an activator After mixing, alkali activation treatment was performed under a nitrogen atmosphere at 800 ° C. for 2 hours to obtain a porous carbon material.

  The obtained porous carbon material was treated in the same manner as in Production Example 1 to obtain activated carbon B.

Production Example 3
To the solid extraction residue X30g of the above-mentioned Australian bituminous coal (raw coal A) whose particle size was adjusted to 2 mm or less, 2.5 times (75 g) of potassium hydroxide in mass ratio (activator / solid extraction residue) as an activator After mixing, alkali activation treatment was performed under a nitrogen atmosphere at 800 ° C. for 2 hours to obtain a porous carbon material. The obtained porous carbon material was washed with water and hydrochloric acid in the same manner as in Production Example 1 to obtain activated carbon. Thereafter, the activated carbon was put into a tube furnace, and the furnace temperature was raised to 1000 ° C. under a nitrogen flow (0.4 L / min) (temperature increase rate: 10 ° C./min). Activated carbon C was obtained by holding for 2 hours after the furnace temperature reached 1000 ° C.

Production Example 4
Activated carbon D was obtained in the same manner as in Example 1 except that instead of the solid extraction residue X of the raw material coal A, the solid extraction residue Y of the raw material coal B whose particle size was adjusted to 1 to 2 mm was used.

Production Example 5
Activated carbon E was obtained in the same manner as in Example 2 except that the same solid extraction residue Y of the raw material coal B as in Production Example 4 was used instead of the solid extraction residue X of the raw material coal A.

Comparative production example 1
A paper-phenolic resin laminate was used as a raw material. 100 g of a paper-phenolic resin laminate is put into a rotary baking furnace (Tanakatec Co., Ltd. rotary kin: capacity 2.5 L), and the furnace temperature is raised to 900 ° C. under nitrogen flow (1 L / min) ( The heating rate was 10 ° C./min.

  After reaching 900 ° C., steam (steam partial pressure 71.2 kPa) was supplied together with nitrogen (1.0 L / min) into the rotary firing furnace, and steam activation treatment was performed for 2.0 hours to obtain activated carbon F.

Comparative production example 2
Coconut charcoal activated carbon (MC Evatech W10-30) was used as activated carbon G.

Comparative production example 3
Activated carbon (MSP-20 manufactured by MC Evatech Co., Ltd.) obtained by subjecting the paper-phenolic resin laminate to alkali activation treatment was defined as activated carbon H.

Comparative production example 4
Activated carbon obtained by subjecting petroleum pitch coke to alkali activation treatment (MC Evatech Co., Ltd., MSC-30) was designated as activated carbon I.

(Activated ash content (%))
The ash content (%) of the activated carbon was measured according to industrial analysis (JIS M8812).

(Specific surface area, total pore volume and average pore diameter)
After 0.2 g of activated carbon was heated at 150 ° C. under vacuum, an adsorption isotherm obtained by a nitrogen gas adsorption method was obtained using a nitrogen adsorption device (“ASAP-2400” manufactured by Micromeritics Co., Ltd.) The surface area was calculated. The total pore volume was determined from the amount of nitrogen adsorbed when the relative pressure P / P ₀ (P: gas pressure of the adsorbate in adsorption equilibrium, P ₀ : saturated vapor pressure of the adsorbate at the adsorption temperature) was 0.93. .

Moreover, the average pore diameter was calculated based on the following formula (1) using the specific surface area and the total pore volume.
Average pore diameter (nm) = (4 × total pore volume (mL / g)) / (specific surface area (m ² / g)) × 1000 (1)

(Total volume of pore diameter 0.05 to 5 μm)
After sieving the activated carbon to 53-300 μm, a mercury porosimeter (Poremaster GT manufactured by Yuasa Isonics Co., Ltd.) is used, and the mercury pressure is measured in the range of 1.37 × 10 ^{−3 to} 404 MPa, and the pressure is 4.26 ×. The total volume of pore diameters of 0.05 to 5 μm at 10 ^{−2 to} 4.26 MPa was calculated. (In Table 1, “total volume (mL / g)”). The results are shown in Table 1, and the pore size distribution of each activated carbon is shown in FIG. In FIG. 1, the pore size distribution exceeding the pore size of 5 μm includes pores due to interparticle voids, and is therefore excluded from the total volume of pore diameters of 0.05 to 5 μm calculated this time.

(Presence or absence of distribution peak in the region of pore diameter of 0.1 μm to 3 μm)
From the pore diameter distribution diagram of FIG. 1, the maximum peak position of the pore volume was identified. When the maximum peak of the pore volume was within the range of the pore diameter of 0.1 μm to 3 μm, “Yes” was entered in Table 1 (“Distribution peak” in Table 1).

(Total volume of pore diameter per specific surface area of 0.05 to 5 μm)
Based on the measured specific surface area and the total volume of pore diameters of 0.05 to 5 μm, the total volume of pore diameters per specific surface area of 0.05 to 5 μm was calculated (in Table 1, “total volume (μL / m ² ) ").

(Adsorption speed)
After putting activated carbon (0.13 g) into a 100 mL Erlenmeyer flask, it is filled with an aqueous solution of TCA (1,1,1-trichloroethane) adjusted to a concentration of 5 mg / L, and at 20 ° C. for a predetermined time (5 minutes, 10 minutes, 30 Minute, 1 hour, 2 hours, 14 hours), the mixture was adsorbed by stirring, and the equilibrium achievement rate (%) at each time was calculated from the residual TCA concentration at each time, and the results are shown in FIG.

FIG. 3 shows the relationship between the equilibrium arrival rate (5 minutes after the start) and the total volume (mL / g) of the pore diameter of 0.05 to 5 μm, and the equilibrium arrival rate (5 minutes after the start) and the specific surface area. The relationship with the total volume (μL / m ² ) of per pore diameter of 0.05 to 5 μm is shown in FIG.

  The following can be seen from FIG. The position of the peak of the pore volume distribution and the total volume of pore diameters of 0.05 to 5 μm satisfy No. 1 of the present invention. In Nos. 1 to 5, the initial equilibrium arrival rate 5 minutes after the start of the adsorption test was as high as 70% or more, and the initial adsorption rate was excellent. In particular, the total volume with a pore diameter of 0.05 to 5 μm satisfies the more preferable range (0.47 mL / g or more) of the present invention. Nos. 1 and 3 to 5 have an initial equilibrium achievement rate of 80% or more, and No. 1 satisfying a more preferable range (0.5 mL / g or more). Nos. 1, 3, and 4 had an initial equilibrium arrival rate of 90% or more, and showed particularly excellent initial adsorption rates.

  On the other hand, the peak position of the distribution defined by the present invention and the total volume of pore diameters of 0.05 to 5 μm were not satisfied. 6 to 9 had an initial equilibrium achievement rate of less than 70%, and the initial adsorption rate was inferior.

4 shows that the total volume of pore diameters of 0.05 to 5 μm per specific surface area satisfies the preferred range of the present invention (0.2 μL / m ² or more). 1 to 5 show that the initial equilibrium achievement rate is as high as 70% or more, and the initial adsorption rate is excellent. On the other hand, the total volume of pore diameters of 0.05 to 5 μm per specific surface area did not satisfy the preferred range (0.2 μL / m ² or more) of the present invention. 6 to 9 show that the initial equilibrium achievement rate is less than 70%, and the initial adsorption rate is inferior.

  As a raw material of activated carbon, No. 1 was used in which a solid extraction residue produced when a carbonaceous material was extracted with an organic solvent was activated. Nos. 1 to 5 are No. 1 using other than the solid extraction residue. Compared with 6-9, the initial equilibrium achievement rate was as high as 70% or more, and the initial adsorption rate was excellent.

  When examining in more detail, in the activated carbon F to I using a material with low raw material ash content, the total pore volume, the total volume of the pore diameter of 0.05 to 5 μm, and the total of the pore diameter of 0.05 to 5 μm per specific surface area The volume was small and the initial equilibrium achievement rate was low. Especially for materials with low raw material ash content (activated carbon H: paper-phenolic resin laminate, activated carbon I: petroleum pitch coke), the total volume with a pore diameter of 0.05 to 5 μm and the fine per specific surface area even with alkali activation treatment. The total volume with a pore size of 0.05-5 μm could not be increased.

  On the other hand, if the amount of raw material ash is large, the total pore volume, the total volume of pore diameters of 0.05 to 5 μm, and the total volume of pore diameters of 0.05 to 5 μm per specific surface area increase, and the initial equilibrium achievement rate increases. . In particular, the larger the raw material ash, the larger the total volume of pore diameters 0.05 to 5 μm and the total volume of pore diameters 0.05 to 5 μm per specific surface area (contrast with activated carbon A and D), When the amount of the alkali activator used is small, ash cannot be sufficiently removed, and the total volume of pore diameters of 0.05 to 5 μm and the total volume of pore diameters per specific surface area of 0.05 to 5 μm and the total pore volume (Active carbon B and C).

  Further, when raw material coal having a fine particle size is used, the specific surface area, the total pore volume, the total volume of pore diameters of 0.05 to 5 μm, and the total volume of pore diameters per specific surface area of 0.05 to 5 μm tend to increase. (Contrast of activated carbon A and activated carbon C).

1: Tank 2: Pump 3: Preheater 4: Extraction tank 5: Gravity sedimentation tank 6: Solid phase component concentrate receiver 7: Filter member 8: Filter unit 9: Supernatant liquid receiver 10: Stirrer 12: Stirrer 13: Stirrer

Claims (7)

  Activated carbon having a distribution peak in a region having a pore diameter of 0.1 to 3 μm and a total volume of pore diameters of 0.05 to 5 μm being 0.4 mL / g or more when the pore size distribution of primary particles is measured. The activated carbon according to claim 1, wherein the total volume of pore diameters of 0.05 to 5 µm per specific surface area is 0.2 µL / m ² or more. The activated carbon according to claim 1 or 2, wherein the specific surface area is 800 m ² / g or more and the total pore volume is 0.4 mL / g or more. The activated carbon according to any one of claims 1 to 3 , wherein the ash content in the solid residue is 5 mass% or more. The adsorbent using the activated carbon in any one of Claims 1-4 . The electrode material for electric double layer capacitors using the activated carbon in any one of Claims 1-4 . The step of extracting the coal with an organic solvent having a temperature of 200 ° C. or higher, and the solid extraction residue that is the undissolved portion of the organic solvent remaining in the extraction treatment, the mass ratio of the solid extraction residue to the alkali activator is 0.5. As mentioned above, the manufacturing method of activated carbon which has the process of carrying out an alkali activation process by setting the heating temperature of an activation process to 600 degreeC or more and the heating time of an activation process to 0.1 hour or more .

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