JP2007153684A - Activated carbon and method for manufacturing pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve a health problem of workers caused by granulating a powdery activated carbon and manufacturing a granular activated carbon and to resolve the adverse effect on electric equipment. <P>SOLUTION: The method for manufacturing a pellet comprises pelletizing by performing compression molding of a material containing 5 to 100% of a steamed biomass, in which the biomass is steamed so as to generate solubilization of a lignin component in the biomass and a thermal plasticity develops in the biomass. The biomass which is a raw material of an activated carbon is granulated at the stage of the raw material so as to obtain the granular activated carbon. The method for manufacturing the activated carbon comprises carbonizing and activating the pellet obtained by the method. The activated carbon is obtained by leaving the obtained activated carbon as it is or after crushing or classifying. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to activated carbon and a method for producing pellets.

  As shown in Patent Document 1, the method of producing pellets by compression molding biomass raw materials has not been widely spread because the production apparatus becomes a large-scale facility. In recent years, small pelletizers have been developed and marketed, but the molding pressure is limited and hard pellets cannot be produced. Furthermore, in a machine equipped with a flat die, biomass (wood, bamboo, etc.) could not be made into small diameter pellets having a diameter of 4 mm or less.

Moreover, activated carbon using biomass as a raw material has been manufactured and marketed for a long time, but there are problems with handling during transportation and use, which is predominantly in powdery form. As shown in Patent Document 2, it is common to granulate powdered activated carbon and use it as granular activated carbon, but the granulation process of low-density carbon solid is a working environment where carbon dust flies, There is a problem of harming health. Moreover, due to the conductivity of carbon, there is an adverse effect on electrical equipment, and measures against dust explosions are required. For this reason, activated carbon production had to be a large-scale factory production.
JP 59-102989 JP 7-267619 A

  Then, this invention makes it a subject to provide the manufacturing method of activated carbon which can also use a small pelletizer, and the manufacturing method of high specific surface area activated carbon. Another object of the present invention is to eliminate the above-mentioned problems such as harming the health of workers by granulating into activated carbon at the stage of biomass, which is a raw material of activated carbon, and to reduce the production of activated carbon.

  Invention of Claim 1 is a pellet manufacturing method characterized by compression-molding the material containing 5-100 parts of steamed biomass, and pelletizing.

  “Steamed” as used herein refers to treating biomass with high-temperature, high-pressure saturated steam. Steaming causes solubilization of the lignin component of the biomass, and the biomass develops thermoplasticity.

  Invention of Claim 2 is the activated carbon manufacturing method characterized by carbonizing and activating the pellet manufactured by Claim 1.

  The use of “activated carbon” can be used for water supply, wastewater treatment, food purification, capacitor use, and the like. “Carbonation” means heating in an oxygen-free or dilute oxygen state indirectly or directly to charcoal by thermal decomposition. “Activation” means reacting carbonized gas or water vapor with the charcoal to form pores. And making it a porous material.

  Invention of Claim 3 is activated carbon obtained after the activated carbon manufactured by Claim 2 as it is or after crushing and classifying.

  According to the first aspect of the present invention, the biomass raw material is steamed before the pellet production, whereby the biomass raw material can be made thermoplastic, and a small pelletizer having a small diameter and hardness can be produced. Moreover, biomass can be pelletized with a small pressure by steaming the biomass material. Furthermore, it becomes possible to make biomass (wood, bamboo, etc.) into small-diameter pellets having a diameter of 4 mm or less with a machine equipped with a flat die.

  According to the invention of claim 2, by granulating biomass at the raw material stage to produce granular activated carbon, compared with the case of producing granular activated carbon by granulating powdered activated carbon as in the past, Processes such as pulverization and granulation of activated carbon in carbon dust can be omitted, and there is no harm to the health of workers. In addition, because of the conductivity of carbon, there is no adverse effect on electrical equipment. This production method for obtaining granular activated carbon by carbonizing and activating biomass small-diameter pellets is a production method in which coarsely crushed carbide is activated and then crushed again, or general granular activated carbon produced by granulating powdered activated carbon It is a simple process compared to the manufacturing method. Furthermore, since the pelletizing apparatus can be reduced in size, the granular activated carbon of biomass distributed widely and shallowly in combination with a small carbonization activation apparatus developed by the present inventor (for example, an apparatus described in JP-A-2005-67972). Can be achieved without the construction of a large-scale factory.

  According to invention of Claim 3, the carbonization / activation material of the pellet which compression-molded biomass, such as steamed wood which can solubilize lignin and can exhibit thermoplasticity, The carbonization / activation material of the pellet compression-molded without steaming Thus, it is possible to obtain a high specific surface area and a high pore volume that cannot be obtained by the above method. If the pore volume per unit weight of activated carbon is large, the amount of adsorbed substances adsorbed per unit weight of activated carbon can be increased.

  Hereinafter, preferred embodiments of the present invention will be described. First, as Embodiment 1, a pellet manufacturing method (Steps 1 to 3) and an activated carbon manufacturing method (Steps 1 to 5) will be described.

Process 1 [steamed]
The form of raw material biomass is biomass itself, which is a crushed chip and powder. As an example of raw material biomass, a process of steaming bamboo (sugi may be used instead of bamboo) is performed. The raw material is put into a steaming device and treated with saturated steam at a temperature of 180 ° C. or higher for 1 minute or longer. Here, the treatment is performed at 180 ° C. for 20 minutes. When bamboo is steamed with high-temperature and high-pressure saturated steam, cell wall components (holocellulose and lignin) are hydrolyzed by water vapor, and the molecular weight of the cellulose to cellulose and lignin is reduced. A high-temperature and high-pressure kettle is mainly used as an apparatus for steaming biomass. The high temperature and high pressure kettle may be a continuous type apparatus or a batch type apparatus.

Step 2 [Crushing]
Non-powdered steamed products are crushed to form pellets. If crushing or crushing to the desired size before cooking, crushing here is not necessary. Grind to a size equal to or less than the target pellet diameter. Here, since the pellets having a diameter of 3 mm are mainly produced, they are pulverized to 3 mm or less.

Step 3 [Pelletization]
The cooked material is compression molded with a small pelletizer and cut to produce 3φ pellets. Since a ring-shaped die like Patent Document 2 is a large-scale device, a small pelletizer using a flat die is used here. The disadvantage of the small pelletizer is that the pellet molding pressure is lower than that of the ring-shaped die, and it is impossible to produce small-diameter pellets. In this embodiment, steamed biomass is improved in the fluidity of the biomass itself due to solubilization of lignin. Therefore, pelletization is possible even if the pressure is low. A pellet having a diameter of 3 mm was prepared with a flat die.

Process 4 [carbonization]
The pellets were carbonized by maintaining the heating rate at 5 ° C./min and holding at 850 ° C. for 30 minutes. Although the carbonization temperature rising rate depends on the heating capability of the apparatus, 1 ° C. to 20 ° C./min, particularly 1 ° C. to 5 ° C./min is desirable. The carbonization temperature is preferably 350 ° C to 1200 ° C and 600 ° C to 900 ° C. The carbonization time is preferably 5 to 120 minutes.

Process 5 [activation]
Activated carbon is produced by carbonizing and activating 3φ pellets. There are two types of activation methods, chemical activation and gas activation, and either method may be adopted. In chemical activation, a method of treating with zinc chloride, phosphoric acid or concentrated sulfuric acid is exemplified, and in gas activation, a method of contact reaction with a gas such as water vapor, carbon dioxide, air, oxygen or the like is exemplified. Here, steam gas activation was performed. While supplying steam in a rotary kiln external heat type activation furnace, it was held at 850 ° C. until a predetermined yield was obtained. In general, steam is used as the activation gas. In chemical activation, activated carbon with fine pores is created by suppressing the formation of tar at high temperature, adding and infiltrating chemicals that erode the fiber of the wood material, and carbonizing the pellet at a temperature of 500 to 700 ° C with air cut off. Can be manufactured. This reaction includes complicated processes such as dehydration, condensation, polymerization, carbonization, and oxidation. In gas activation, when pellets and gas (water vapor, carbon dioxide, air, combustion gas, etc.) are reacted at a temperature of 700 to 1000 ° C., fine pores are generated by carbon partial reaction, and activated carbon is produced. Furthermore, granular activated carbon can be obtained by crushing and classifying the activated carbon thus produced.

  In addition, activated carbon can be manufactured from various organic substances, for example, coal, coconut shells, large sawdust and the like. Furthermore, activated carbon can be classified into powdered activated carbon and granular activated carbon. In general, raw materials used as powdered activated carbon include sawdust, hard wood chip, charcoal (primary ash), grass charcoal (peat), etc., granular activated carbon Examples of raw materials used include charcoal, coconut shell charcoal, coal (lignite, lignite, bituminous coal, anthracite, etc.), oil carbon, and phenol resin.

In the present embodiment, 3φ pellets are manufactured, but this value is not limited, and the pellet diameter can be set to any value by changing the extrusion hole diameter of the die. In the following table, the experimental results by the present inventors comparing the specific surface area, pore volume, etc. of activated carbon produced from pellets obtained without cooking, activated carbon produced from pellets obtained by cooking, etc. are shown. .

  Comparative Example 1-1 is obtained by carbonizing and activating bamboo after crushing bamboo into 8 to 16 meshes. In Comparative Example 1-2, steamed bamboo was crushed, carbonized and activated. Comparative Example 1-3 is obtained by carbonizing and activating bamboo that is not steamed into 6φ (diameter 6 mm, hereinafter the same) pellets. In Embodiment 1-1, steamed bamboo is made into 3φ pellets and then carbonized and activated. In Embodiment 1-2, steamed bamboo is made into 3φ pellets and then carbonized and activated. In Embodiment 1-3, steamed bamboo is made into 4φ pellets and then carbonized and activated. In Table 1, “<diameter 2 nm” is a total value of pore volumes formed by pores having a diameter up to 2 nm. In Table 1, “<diameter 1 nm” is the total value of pore volumes formed by pores having a diameter up to 1 nm. Although Example 1-1 and Example 1-2 are the same, the comparison object is different.

  According to Table 1, the activated carbon obtained by crushing bamboo into 8-16 mesh and then carbonized and activated and the activated carbon obtained by crushing steamed bamboo and carbonized and activated were compared. There was no significant difference in pore volume. From this experimental result, it can be concluded that the presence or absence of steaming does not affect the pore structure in the activated carbon after carbonization / activation unless pelletized.

Next, as a result of comparing activated carbon obtained by carbonizing and activating 6φ pellets without steaming, and activated carbon obtained by carbonizing and activating activated steamed bamboo after making 3φ pellets, there is a large difference in pore volume. It was observed. From this experimental result, when carbonizing and activating after pelletization, it was concluded that the presence or absence of steaming greatly affects the pore structure of activated carbon.

  Comparison of activated carbon obtained by crushing, carbonizing and activating steamed bamboo, and activated carbon obtained by carbonizing and activating activated steamed bamboo after making steamed bamboo into 3φ pellets showed a large difference in pore volume. . From this experimental result, it was possible to conclude that the presence or absence of pelletization in the steamed raw material greatly affects the pore structure in the activated carbon after carbonization and activation.

  Finally, as a result of comparing the activated carbon obtained by carbonizing and activating the steamed bamboo after making it into 4φ pellets and the activated carbon obtained by carbonizing and activating the steamed bamboo after making it into 3φ pellets, the pore volume A big difference was seen. From this experimental result, it can be concluded that the pellet diameter has a great influence on the pore structure.

Below, the effect by this embodiment is described. According to the present inventor, a research result that a 4φ, 3φ pellet cannot be stably produced with a raw material without steaming as in this embodiment is obtained. According to the production method of this embodiment, 4φ, 3φ Pellets can be produced. The activated carbon obtained by the production method of the present embodiment has a high specific surface area of 1720 m ² / g, a pore volume of 1.25 ml / g, and a micropore volume of 2 mm or less in diameter is very high at 77.4%. Sharp pore distribution. Activated carbon made from bamboo is known to have a high micropore ratio, but according to this embodiment, the characteristics are further enhanced. A porous material having a large micropore volume is excellent in adsorbing a low molecular weight material, and coconut shell activated carbon is typical. Many coconut shell activated carbons having a specific surface area of about 1000 m ² / g are produced and used. According to this embodiment, activated carbon having a high specific surface area and a high micropore ratio can be obtained using bamboo as a raw material.

  By steaming the biomass material before pellet production, the biomass material can be made thermoplastic, and even a small pelletizer can produce pellets with a small diameter and hardness. Further, by steaming the biomass material, it becomes possible to pelletize the biomass with a small pressure, and it is also possible to make biomass such as wood and bamboo into small-diameter pellets even with a machine equipped with a flat die.

  By pulverizing biomass at the raw material stage to produce granular activated carbon, compared to the case where granular activated carbon is produced by granulating powdered activated carbon as in the past, pulverization of activated carbon in carbon dust, The process such as granulation can be omitted, and the health of workers is not harmed. In addition, because of the conductivity of carbon, there is no adverse effect on electrical equipment. The present embodiment for obtaining granular activated carbon by carbonizing and activating biomass small-diameter pellets is generally manufactured by pulverizing and pulverizing coarsely divided carbide again, or by granulating powdered activated carbon. This is a simple process compared to a simple granular activated carbon manufacturing method. Furthermore, since the pelletizing apparatus can be reduced in size, the granular activated carbonization of biomass that is widely and shallowly distributed by combining with a small carbonization activation apparatus developed by the present inventor (apparatus described in JP-A-2005-67972) can be achieved. This can be done regardless of the construction of a large-scale factory.

  The above embodiment is a representative example of the technique employed by the present inventors in carrying out the aspects of the present invention. These techniques are examples of preferred embodiments for carrying out the present invention, and those belonging to the present technical field will not depart from the spirit and intended gist of the present invention in view of the disclosure of the present invention. Many improvements, changes, modifications, additions, etc. are possible.

Claims (3)

  A pellet manufacturing method comprising compression-molding a material containing 5 to 100 parts of steamed biomass into pellets.   The activated carbon manufacturing method characterized by carbonizing and activating the pellet manufactured by Claim 1.   Activated carbon obtained by directly or after crushing and classifying the activated carbon produced according to claim 2.