JP4718303B2 - Method for producing activated carbon - Google Patents

Description

  The present invention relates to a method for producing activated carbon, and more particularly to a method for producing activated carbon that is suitably used as an adsorbent and an electrode material for an electric double layer capacitor.

  As a method for producing activated carbon, a method of activating a carbon material has been conventionally used. As a method of activating the carbon material, a method of activating using a multi-stage furnace, a rotary kiln furnace, a fluidized bed furnace or the like is known.

  When performing the activation treatment, it is important to activate the carbon material uniformly. Here, from the viewpoint of uniformly activating the carbon material, it is compared to using a fluidized bed furnace or a rotary kiln furnace with stirring blades that can increase the contact area between the activation gas used for activation and the carbon material that is the raw material. Advantage.

  However, in the above fluidized bed furnace or rotary kiln furnace, when a raw material having a small particle size, such as a spherical phenol resin having an average particle size of less than 20 μm, is used, the particle size is too small to be activated. There's a problem. For example, in a rotary kiln furnace, if the gas velocity of the activation gas is increased, problems such as scattering of raw materials occur and the yield decreases. Further, in a fluidized bed furnace, there is a problem that a raw material having a too small particle size cannot maintain a good fluidized state and cannot be activated uniformly.

For such a problem, for example, Patent Document 1 discloses that a water-soluble phenol resin, liquid pitch, polyvinyl alcohol (PVA), carboxymethyl cellulose, gelatin or the like is used as a binder and granulated to about 3 mm. A method for gas activation is described.
JP 2001-143973 A

  However, the water-soluble phenolic resin, polyvinyl alcohol (PVA), carboxymethyl cellulose, and gelatin used as the binder at the time of granulation described in Patent Document 1 are the residual carbon ratio at a temperature of, for example, about 400 ° C. Becomes near zero. Therefore, when these are used alone as a binder, the granulated material is separated and is easily finely divided. For this reason, for example, when carbonizing and activating in a fluidized bed furnace, it is not possible to maintain a good fluidized state, the activation becomes non-uniform, that is, the specific surface area is not so large, and the variation in specific surface area is large. There is a problem.

  Moreover, it is thought that the pitch used as the binder at the time of granulation described in the said patent document 1 fully exhibits the function as a binder by carbonizing. However, when the pitch is used alone, when the temperature is low, for example, when the temperature is 400 ° C. or lower, the function as a binder is not sufficient, and when the granulated material is flowed at a low temperature, it becomes disintegrated and tends to be finely divided. For this reason, when carbonizing and activating in a fluidized bed, there is a problem that a good fluidized state cannot be maintained and activation is not uniform, that is, the specific surface area is not so large and the variation in specific surface area becomes large. There is.

  Then, this invention aims at providing the manufacturing method of activated carbon with a large specific surface area and a small dispersion | variation in a specific surface area by always enabling activation uniformly.

  The present inventors have studied a method capable of always performing uniform activation from a low temperature state to a high temperature state at the time of temperature increase during the activation treatment.

  As a result, it has been found that the above-mentioned problems can be solved by using “pitch” and “polyvinyl alcohol (PVA)” together as a binder during granulation. That is, at low temperatures (for example, 400 ° C. or lower), “polyvinyl alcohol” functions as a binder, and at high temperatures (for example, 400 ° C. or higher), “pitch” functions as a binder, so that the shape of the granulated product is carbonized and activated. It has been found that activated carbon having a large specific surface area and a small variation in specific surface area can be produced.

The present invention has been made based on the above findings and has the following characteristics.
[1] Phenol resin powder: 89 to 98.9 mass%, pitch: 1 to 10 mass%, and polyvinyl alcohol: 0.1 to 1 mass%, mixed and granulated, and then the granulated mixture is mixed. A method for producing activated carbon which is carbonized and activated.
[2] The method for producing activated carbon according to [1], wherein the activated carbon obtained after the activation is crushed and classified.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to always perform activation uniformly and the manufacturing method of activated carbon with a large specific surface area and a small dispersion | variation in a specific surface area is provided.

  Hereinafter, an example of the best mode for carrying out the present invention will be described.

  The method for producing the activated carbon of the present invention comprises mixing phenol resin: 89-98.9% by mass, pitch: 1-10% by mass, and polyvinyl alcohol: 0.1-1% by mass, The granulated mixture is carbonized and activated.

  Furthermore, in the present invention, it is preferable that the activated carbon obtained after the activation is crushed and classified. Thereby, it becomes possible to obtain activated carbon adjusted to a particle diameter in a predetermined range.

  Hereinafter, each component of the present invention will be described in detail.

[Phenolic resin]
Content of the said phenol resin contained in the mixture which is a raw material shall be 89-98.9 mass%. If the content of the phenol resin is less than 89% by mass, the yield of the activated carbon obtained is lowered,
When the amount exceeds 98.9% by mass, the amount of binder such as pitch and PVA decreases, so that it is difficult to maintain the shape of the granulated product during carbonization and activation.

  Moreover, as a kind of the said phenol resin, a normal thing, such as a novolak type and a resol type, can be used. Moreover, there is no restriction | limiting in particular as a shape of the said phenol resin, However, It is preferable to use a spherical thing. Spherical phenolic resin is obtained by shaping the phenolic resin into a spherical shape, and activated carbon with a large specific surface area can be obtained by activation. Therefore, the adsorption performance of spherical activated carbon produced from this spherical phenolic resin is more excellent. Become a thing.

  Furthermore, since the spherical phenol resin is formed into a spherical shape unlike crushed coal, the spherical activated carbon obtained by the carbonization and activation thereof has no angular portion on the surface. For this reason, not only during transportation but also when used in a fluidized bed type apparatus, the corners of the surface of the activated carbon particles are less likely to be rubbed to produce fine powder. Therefore, there is no adverse effect on the apparatus due to the fine powder, and the fine pores on the surface of the activated carbon particles are not broken and the adsorption performance and the like are not deteriorated.

  The average particle size of the phenol resin is preferably less than 20 μm. More preferably, it is 1 μm or more and less than 20 μm.

[pitch]
Content of the said pitch contained in the mixture which is a raw material shall be 1-10 mass%. When the pitch content is less than 1% by mass, the granulated shape cannot be maintained during the heat treatment in the carbonization step and the activation step. The purity does not increase and is not preferable.

  Further, the pitch is not particularly limited, but it is preferable to use a pitch having a large residual carbon ratio (carbonization yield) during carbonization. For example, the residual carbon ratio of a solid pitch having a melting point range of 50 to 350 ° C. is usually 50 to 95% by mass, and the residual carbon ratio of a liquid pitch having a melting point range of 30 to less than 50 ° C. is usually 30 to 50% by mass. Therefore, it is preferable to use a solid pitch.

[PVA]
Content of polyvinyl alcohol (PVA) contained in the mixture which is a raw material shall be 0.1-1 mass%. When the PVA content is less than 0.1% by mass, the granulated shape cannot be maintained until the pitch is softened and melted to function as a binder, which is not preferable. If it exceeds 1% by mass, an appropriate gap cannot be maintained between the raw material phenol resins, and the activation gas is not sufficiently diffused between the raw materials and is not activated uniformly. In addition, water-soluble phenol resin, cellulose, gelatin, molasses, etc. that are considered to exhibit the same role as PVA may be used at a low temperature (for example, 400 ° C. or lower).

  The method for mixing the above-described phenol resin, pitch, and PVA is not particularly limited. It may be dry mixing or may be wet mixing. However, in order to uniformly disperse PVA, it is preferable to mix these in the form of an aqueous solution or a dispersion.

  Moreover, it is not specifically limited as a granulation method of the mixture of the said phenol resin, pitch, and PVA, Rolling granulation, fluidized bed granulation, ejection layer granulation, disintegration granulation, compression granulation, extrusion granulation, etc. The usual granulation method can be applied.

  Here, as the particle shape of the granulated product, it is preferable to make it coarse particles of about 0.1 to 3 mm.

  In addition, as a carbonization method for carbonizing the granulated mixture (granulated product), an inert gas such as nitrogen, argon, helium, xenon, neon, or a non-oxidizing atmosphere of a mixture of two or more of these gases is used. In the temperature range of about 300 to 2,000 ° C., preferably about 500 to 1,300 ° C., by heating and granulating the granulated product for about 10 minutes to 30 hours.

  Moreover, it does not specifically limit as an activation method of the carbide | carbonized_material after carbonizing the said granulated material, Various well-known and usual activation methods can be used. For example, a gas activation method in which water vapor, carbon dioxide gas (combustion gas), oxygen (air), or other oxidizing gas is brought into contact and reaction at a temperature of preferably 700 to 1200 ° C., zinc chloride, phosphate, potassium hydroxide, etc. After impregnating an acid such as an alkali metal compound or sulfuric acid, a chemical activation method by heating at a temperature of preferably 300 to 800 ° C. in an inert gas atmosphere is used. In the case of the chemical activation method, after activation, the product and the chemical used are generally neutralized with an acid or alkali, or removed using water washing or the like.

  In addition, as an apparatus which performs the said carbonization process and activation process, a multistage furnace, a rotary kiln furnace, a fluidized bed furnace etc. can be used, for example.

  Moreover, as a method for crushing the activated carbon obtained after the activation, a hammer mill, a ball mill, a jet mill, an atomizer, or the like can be usually used, and is not particularly limited.

  Moreover, as a classification method of the activated carbon after crushing, an air classifier, a vibration sieve, etc. can be used normally, and it is not specifically limited.

  In the present invention, by eliminating the fine powder contained in the activated carbon after pulverization by the classification step, the pitch-derived crushed material used as the binder can be removed, and the particle diameter is adjusted to a predetermined range. Only activated carbon having a good shape, such as spherical activated carbon, can be obtained with high purity.

  Hereinafter, the effects of the present invention will be described in detail with reference to the present invention examples (Examples 1 to 5) and Comparative Examples 1 to 4. The present invention is not limited to the following examples.

  In the following description, the average particle size was measured by dispersing activated carbon in water containing a surfactant using a laser type particle size meter manufactured by Seishin Co., Ltd.

Moreover, the BET specific surface area of the carbide | carbonized_material and the activation material was measured by Micromeritics Co., Ltd. ASAP2400. The measurement was performed according to the BET formula in the range of relative pressure P / P ₀ = 0.5 to 0.15 after vacuum drying at 200 ° C. to 1.33 Pa (10 mm Torr).

[Example 1]
98.9% by mass of spherical phenol resin powder having an average particle size of 7 μm is mixed with 1% by mass of coal-based pitch fine powder and 0.1% by mass of polyvinyl alcohol (PVA) as an aqueous solution, and averaged by rolling granulation. Granulated into a spherical shape with a particle size of 0.7 mm. Next, carbonization was performed at 600 ° C., and the BET specific surface area was measured. The results are shown in Table 1 below.

  Furthermore, after steam activation at 800 ° C. in a rotary kiln furnace, pulverization and classification were performed to eliminate 2% by mass of fine powder, and spherical activated carbon having an average particle diameter of 7 μm was obtained. The BET specific surface area and standard deviation of this spherical activated carbon were measured. The results are also shown in Table 1 below.

[Examples 2 to 5, Comparative Examples 1 to 4]
Spherical activated carbon was obtained in the same manner as in Example 1 except that the raw materials used in Example 1 and the contents thereof were changed to those shown in Table 1 below. The measurement of the BET specific surface area of the carbide, the BET specific surface area of the spherical activated carbon, and the standard deviation was performed in the same manner as in Example 1, and the results are shown in Table 1 below.

  As shown in Table 1, it was confirmed that Examples 1 to 5 according to the present invention can produce activated carbon having a large specific surface area and a small variation in specific surface area as compared with the comparative example.

  The activated carbon produced by the activated carbon production method of the present invention is usefully used in various industrial fields as an adsorbing material, a catalyst / catalyst support material, a membrane material, an electronic / electrical material, an imaging material, and the like.

Claims (2)

  Phenol resin: 89-98.9% by mass, pitch: 1-10% by mass, and polyvinyl alcohol: 0.1-1% by mass are mixed and granulated, and then the granulated mixture is carbonized and activated. And a method for producing activated carbon.   The method for producing activated carbon according to claim 1, wherein the activated carbon obtained after the activation is crushed and classified.