JP2515919B2 - Method for producing spherical fiber lump activated carbon - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing spherical fiber lump activated carbon from tar pitch as a raw material.

(Prior Art) Activated carbon has innumerable fine pores, has a large outer surface area per unit weight, and has the function of adsorbing and holding various molecules in the gas phase and liquid phase, and also capable of desorbing. Have Therefore, conventionally, activated carbon has taken advantage of its adsorptive and desorbing ability to separate, remove, adsorbent, decomposer,
It is used as a recovery agent, catalyst, and catalyst carrier.

Due to its form, such activated carbon generally has a particle size of 149μ.
It is roughly classified into powdered activated carbon of m or less, granular activated carbon having a particle size of about 1 mm to 3 mm, and amorphous fibrous activated carbon.

In addition, fibrous activated carbon is generally gas activated carbon fiber,
Alternatively, it is a fibrous activated carbon produced by activating chemicals and has a large outer surface area per unit weight and a high adsorption / desorption rate.

On the other hand, as a method for producing spherical activated carbon fibers, a carbon fiber or infusibilized pitch fiber is provided with a liquid containing a carbon-containing resin, and divided or cut in a wet state to form a lump, and the lump is dried. A method of activating treatment after curing is disclosed in JP-A-2-38374, and further,
Regarding fibrous activated carbon using pitch as a raw material, JP-A-60-
167929, JP 61-295217, JP 61-29
6124, JP 61-34225, JP 62-27315
Japanese Patent Laid-Open Publication No. 55-113608 discloses a spherical activated carbon using pitch as a raw material.

(Problems to be Solved by the Invention) The powdered activated carbon has an advantage that it has a large outer surface area per unit weight and a high adsorption rate as compared with the granular activated carbon.
Since the particle size is as small as 149 μm or less, it easily scatters, is generally difficult to handle, and has a risk of dust explosion. In addition, since it has a large ventilation resistance when used in a fixed bed, it is difficult to use in the gas phase, and it is used in a contact batch method in which a treatment liquid and an appropriate amount of activated carbon are mixed and then filtered, and generally a liquid phase is used. Separators, scavengers, adsorbents, decomposers of various molecules in
It has a drawback that it can only be used as a recovery agent and a catalyst carrier. If it is attempted to obtain the effect of adsorbing various molecules of a harmful substance in the gas phase, it is not preferable because it leads to a decrease in the treatment amount, that is, a decrease in the so-called adsorption efficiency.

On the other hand, granular activated carbon is easier to handle than powdered activated carbon, less likely to scatter, there is no risk of dust explosion, and since it has a small airflow resistance when used in a fixed bed, it can be used in both the gas phase and the liquid phase, Further, it has an advantage that it can be reused, but it has drawbacks that it is easily crushed into powder, has a small outer surface area per unit weight, and has a low adsorption rate and desorption rate. Therefore, if the gas or liquid to be purified is flown through the granular activated carbon layer to sufficiently adsorb and remove various molecules of low-concentration harmful substances, a large-capacity granular activated carbon layer is required, and the treatment layer is reduced. This results in a decrease in adsorption efficiency. Furthermore, if a gas or liquid to be purified is passed through a fluidized bed of granular activated carbon and various molecules of harmful substances are adsorbed and removed, the large particle size is about 1 to 3 mm and the large particle density. Gas or liquid flow is required, resulting in a decrease in the adsorption removal rate, which causes wear and crushing loss of the granular activated carbon.

On the other hand, fibrous activated carbon has poor strength and shape retention characteristics as its own fiber aggregate, and is easily scattered, resulting in workability,
It has the disadvantages of poor handleability, high porosity, and low packing density. Also, even if it is recycled or reused, it easily scatters and the shape retention is poor,
There is a problem that the reproducibility of porosity and packing density is poor. Therefore, if the gas or liquid to be purified is allowed to flow through the fibrous activated carbon fixed layer filled with fibrous activated carbon in a cotton shape to sufficiently remove various molecules of harmful substances, a large volume of fibrous activated carbon layer is obtained. Is required, which is not economical and leads to a reduction in throughput, so-called a decrease in adsorption efficiency. Also, when the gas or liquid to be purified is flowed through a fibrous activated carbon fluidized bed filled with fibrous activated carbon in a cotton-like state to adsorb and remove various molecules of harmful substances, the cotton-like fibrous body is shaped. Maintainability is poor, scattering and scattering, wear, and crushing loss are caused, and similarly, the adsorption removal rate decreases, the treatment amount decreases, and so-called adsorption efficiency decreases. Furthermore, in order to improve the shape retention of the woven fabric, the non-woven fabric, the felt, the mat, the paper, etc., it is necessary to use a blended fiber for imparting strength, which is not only economical and costly. The processed product has a problem that the content of the activated carbon fiber is low and thus the outer surface area per unit weight is reduced. Further, there is a problem in that the heat regeneration method using an activated carbon regenerating furnace which is generally performed becomes difficult and the reusing cannot be performed.

On the other hand, in recent years, the function of activated carbon has been improved against the background of social demands such as countermeasures against groundwater pollution by trichlorethylene, etc., measures against trihalomethane of tap water, measures against CFC gas, deodorization, deodorization, and creation of amenity space such as comfort. , Improvement of shape is required.

Therefore, the object of the present invention is to eliminate the drawbacks of the conventional activated carbons described above, that is, powdered activated carbons, granular activated carbons, and fibrous activated carbons, have a high adsorption capacity, a high adsorption / desorption rate, and good handling properties. It is an object of the present invention to provide a method for producing a highly functional spherical fiber lump activated carbon which has good shape retention and is easy to recycle.

(Means for Solving the Problem) As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a non-fusible pitch fiber by infusible after spinning using a pitch prepared for spinning as a raw material. The inventors have found that a highly functional spherical fiber lump activated carbon can be obtained by mixing pitch fibers with the mixture, spheroidizing the spheroidizing particles, and further activating the spheroidizing particles to complete the present invention. Further, instead of the infusible pitch fiber, the same effect can be obtained by using a carbonized fiber obtained by further carbonizing the infusible fiber or a mixed fiber thereof. Furthermore, the mixing ratio of pitch fibers is 5% by weight or more and 50% by weight in the mixed fibers.
It is characterized by the following.

Therefore, the present invention relates to a method for producing a spherical fiber lump activated carbon in which a plurality of fibrous activated carbon fibers are bonded to each other.

Hereinafter, the method for producing the spherical fiber lump activated carbon of the present invention will be described in detail.

The raw material used in the present invention is preferably tar pitch.
This is a polyacrylonitrile type that is conventionally manufactured,
This is because the raw material is cheaper and the activation yield is higher when the pitch is used as the raw material, as compared with the phenol resin type, the cellulose type and the like. Also, the pitch used here is
A suitable material having a high softening point, which has been appropriately made heavy so as to be suitable for spinning, infusibilization and activation in the subsequent step, is suitable, but it is preferably selected from those having a softening point of 180 ° C. or higher. A method for manufacturing such a pitch is disclosed in, for example, Japanese Patent Laid-Open No. 61-00.
As proposed in Japanese Patent No. 2712 etc., those prepared by subjecting to purification, solvent extraction, distillation, heat treatment and the like are suitable.

Next, the pitch is spun, and known methods such as melt extrusion spinning and centrifugal spinning can be used.

Then, the pitch fiber obtained is subjected to infusibilization (oxidation) treatment so that the spherical fiber shape can be maintained when it is activated at a high temperature in a subsequent step, but in an oxidizing atmosphere, 150 to 350 ° C.
It is preferable to carry out at a moderate temperature. Suitable infusibilization conditions are
Although depending on the raw material pitch used, for example, the softening point of the pitch is used as a guide, and the ascending speed, temperature, time, atmosphere gas and the like are appropriately selected.

Furthermore, the infusible fiber obtained is 50% under an inert atmosphere.
The spherical fiber lump activated carbon of the present invention may be produced by carbonizing carbon fibers at 0 ° C. or higher and using the carbon fibers instead of the infusible fibers, and further, mixed fibers thereof may be used.
Hereinafter, the case of infusible fiber will be described as a representative.

Next, the infusible fiber and the pitch fiber are mixed and spheroidized. When the infusible fiber and the pitch are mixed, the pitch fiber acts as a binder that melts during activation in a subsequent step and partially adheres the infusible fiber. That is, when the mixed pitch fibers are melted and the infusible fibers are adhered to each other, the holding power of the spherical fiber shape can be markedly improved, and as a result, the fibers fall off or scatter during handling. Etc. can be extremely reduced.

The mixing ratio of the pitch fibers at this time can be arbitrarily selected, but if the ratio of the pitch fibers used for mixing exceeds 50% by weight in the mixed fibers, fusion proceeds too much and the fiber shape is not maintained. However, the strength is also lowered and the yield is lowered, which is not preferable.

The mixing ratio of pitch fiber is 5% by weight in the mixed fiber.
The above is preferable. If the amount is less than 5% by weight, the effect as a binder is small, which is not preferable.

Next, as a method for spheroidizing, for example, a method has been proposed in which short fiber aggregates of carbon fibers are mixed in a cylindrical container in which a swirling airflow is generated and swirled together with the airflow (Japanese Patent Laid-Open No. 62-114636). However, it is also possible to use mechanical granulation.

Next, as the activation treatment method, a usual gas activation method using water vapor, carbon gas, oxygen, air or the like can be adopted. Usually, in the gas activation method, the characteristics of activated carbon fibers can be controlled by the temperature of activation treatment, time, type and concentration of gas, etc., and the pore diameter, pore distribution, ratio of the fibrous activated carbon to be the final product. The surface area is thereby controlled. As a preferable activation condition when activating gas, the activation temperature is 700 to 1
The activation time is 0 to 240 minutes at 000 ° C, but it is necessary to select the conditions according to the required characteristics. That is, to obtain a fibrous activated carbon having a wide pore size distribution and a large average pore radius, it is suitable to perform a treatment at a high temperature for a short time, and a narrow pore size distribution and an average pore radius of Treatment at low temperature for a long time is suitable for obtaining small fibrous activated carbon. Further, as the activation device, a batch type device may be used, but in the present invention, the fibers are spheroidized, and the pitch fibers are melted and infusibilized fibers in the temperature rising stage in the initial process of activation. Since the balls can be bonded to each other, the shape maintaining characteristics of the balls are good, and the handling property is excellent, so that a continuous activation furnace can also be adopted.

(Working) The spherical activated carbon fiber obtained as described above has a large outer surface area per unit weight, a high adsorption / desorption rate,
Moreover, since it is spherical, it is excellent in workability and handleability, can be filled in any shape, and can be densely filled. In addition, since the shape maintaining property is good, there is little regeneration loss, and recycling is easy. Furthermore, by taking advantage of its high functionality, it can be used for pollution prevention and environmental purification in both liquid and gas phases.

(Example) Example 1 Coal tar pitch was purified by filtration and then heat-treated for benzene insoluble matter (BI) = 57% by weight, quinoline insoluble matter (QI).
= A trace amount of pitch was obtained. Viscosity of the pitch is 100 at 298 ° C
Poise was exhibited, and its softening point was 240 ° C (pitch-
A). This pitch was a uniform pitch showing optical isotropy on the entire surface when observed at 400 times with a polarization microscope.

Next, melt extrusion spinning is performed using these pitches to obtain pitch fibers having a fiber diameter of 20 μm, and then the pitch fibers are heated to 310 ° C. in air at 0.5 ° C./min in a batch type furnace. Infusibilization treatment was performed. Next, each of the infusible fiber-A and the pitch fiber-A is cut into a length of 3 mm to form a chop, and then 10% by weight of the infusible fiber-A is mixed with the infusible fiber-A into a cylindrical container. When inserted and swirled while generating swirling airflow, a spherical infusible fiber mass could be obtained.

Then, the spherical infusible fiber mass was heated in a batch type furnace while flowing nitrogen gas containing 33% by volume of steam in the furnace, and the temperature was maintained at 850 ° C. for 2 hours for activation treatment. went. When the obtained spherical fusion activated fiber was observed with a microscope, it had a three-dimensional network structure in which the fibers were bonded together as shown in FIG. 1a. Also in FIG. 1b,
The perspective view which expanded a part of it is shown. The yield of the obtained spherical fusion-activated fiber was 25% on the basis of spherical infusible fiber, and the specific surface area of the fiber (measured by Micromeritics, Asap 2000, was measured by the Langmuir method. analysis)
Was 2020 m ² / g, the average pore diameter was 17 Å, and the volume ratio of the pore diameter of 10 Å or less by the t-plot method was 60%.

Example 2 The spherical infusible fiber mass obtained in Example 1 was heated in a batch type carbonization furnace by circulating nitrogen gas containing 30% by volume of steam in the atmosphere and holding the temperature at 800 ° C. for 2 hours. By doing so, activation treatment was performed.

The yield of the obtained spherical fusion activated fiber is 50%, the specific surface area of the fiber is 1250 m ² / g, the average pore diameter is 17Å,
The volume ratio of pores with a diameter of 10 Å or less was 85%.

Example 3 The infusible fiber-A and the pitch fiber-A obtained in Example 1 were mixed in a weight ratio of 7: 3, and the mixture was spheroidized and then activated as in Example 1. went.

The yield of the obtained spherical fusion-activated fiber was 20%, the specific surface area of the fiber was 1950 m ² / g, the average pore diameter was 18Å,
The volume ratio of pores with a diameter of 10 Å or less was 55%.

Example 4 The infusible fiber-A obtained in Example 1 was placed in argon gas.
Carbonization treatment was performed at 1000 ° C. to obtain carbonized fiber-A. Pitch fiber-
A, infusible fiber-A, and carbonized fiber-A were each cut into 3 mm length and made into chips, and then by weight ratio, pitch fiber-A / infusible fiber-A / carbonized fiber-A = 10/45 / The mixture was mixed at a ratio of 45, spheroidized in the same manner as in Example 1, and then activated. The yield of the obtained spherical activated fiber is 27%,
The specific surface area was 1900 m ² / g and the average pore size was 16Å.

Comparative Example 1 Infusible fiber-A and pitch fiber-A were mixed in a weight ratio of 4 to 6 in the same manner as in Example 3, spheroidized in the same manner as in Example 1, and activated to give spherical fibers. However, the fibers did not retain their shape, and a trace of foaming was observed on the sphere. Also, the spheres were very brittle and easily pulverized, and could not be obtained as spherical activated carbon fibers.

(Effects of the Invention) As described above, the method of the present invention can efficiently produce spherical fiber lump activated carbon from coal tar pitch as a raw material. Moreover, this spherical fibrous lump activated carbon has a higher adsorption capacity than conventional activated carbon, that is, granular activated carbon, powdered activated carbon, and fibrous activated carbon, and has a fast adsorption / desorption rate, good handling properties, and shape retention characteristics, and can be recycled. Are easy to use and have improved functionality.

Therefore, such a spherical fiber lump activated carbon has extremely excellent properties as an activated carbon used in a wide range of industrial fields by utilizing a high adsorption / desorption capacity and a large specific surface area.
In addition to pollution prevention and environmental purification, it can be used in a wide range of fields such as the food industry and the petroleum industry, and is extremely useful industrially as an essential component of advanced processing technology.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing a three-dimensional network structure in which the fibers of the spherical fiber lump activated carbon obtained by the method of the present invention are bonded to each other, and FIG. 1 (b) is A of FIG. 1 (a). The perspective view which expanded the part shown by is shown.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Hanatani 1 Kawasaki-cho, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Mamoru Kamisha 1 Kawasaki-cho, Chiba City Kawasaki Steel Co., Ltd. Shiki Company Technology Research Division

Claims (3)

(57) [Claims] 1. A method for producing spherical fibrous lump activated carbon from tar pitch as a raw material, which is spun from pitch as a raw material, infusibilized, and pitch fibers are mixed with the infusible fiber to be spheroidized, followed by activation. A method for producing a spherical fiber lump activated carbon, which comprises: 2. A carbonized fiber obtained by further carbonizing the infusible fiber according to claim 1, or a mixed fiber of the infusible fiber and the carbonized fiber according to claim 1. 2. Use in place of the infusibilized fiber.
A method for producing the spherical fiber lump activated carbon described. 3. The mixing ratio of pitch fibers is 5 in the mixed fibers.
The activated fiber is activated after being spheroidized by using a mixed fiber of not less than 50% by weight and not more than 50% by weight.
A method for producing the spherical fiber lump activated carbon described.