JP2556598B2 - Method for producing spherical fiber lump activated carbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention uses tar pitch as a raw material and is a highly functional fibrous activated carbon that is indispensable for advanced treatment technology used in pollution prevention and environmental purification, food industry, petroleum industry and the like. The present invention relates to a method of manufacturing.

(Prior Art) Activated carbon has innumerable fine pores, has a large outer surface area per unit weight, and is capable of adsorbing, retaining, and desorbing various molecules in the gas phase and liquid phase. 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, catalyst carrier, etc.

(Problems to be solved by the invention) Activated carbon is generally composed of powdered activated carbon having a particle size of 149 μm or less and granular activated carbon having a particle size of about 1 mm to 3 mm.
It is roughly classified into amorphous fibrous activated carbon. Here, the powdered activated carbon has an advantage that the outer surface area per unit weight is larger and the adsorption rate is faster than the granular activated carbon, but the particle size is smaller.
Since it is as small as 149 μm or less, it easily scatters, is generally difficult to handle, and has a risk of dust explosion. Further, 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, Separators, scavengers, adsorbents, decomposers of various molecules in the phase,
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, the amount of treatment, that is, the so-called adsorption efficiency is lowered, which is not preferable.

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 ventilation resistance when used in a fixed bed, it can be used in both the gas phase and the liquid layer, Further, it has the advantage that it can be reused, but it also has the drawbacks that it is easily crushed into powder, the external surface area per unit weight is small, and the adsorption and desorption rates are slow. Therefore, if the gas or liquid to be purified is flowed through the granular activated carbon layer and various molecules of low-concentration harmful substances are sufficiently adsorbed and removed, a large-capacity granular activated carbon layer is required, and the amount of treatment is reduced. That is, the so-called adsorption efficiency is lowered. Also, if the 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. The above gas or liquid flow is required, which leads to a decrease in the adsorption removal rate, which causes wear of the granular activated carbon and crushing loss.

On the other hand, fibrous activated carbon is generally a fibrous activated carbon produced by gas-activating or chemical-activating carbon fiber, which has a large outer surface area per unit weight and has an advantage that the adsorption / desorption rate is fast, The strength and shape retention of the fiber assembly itself is poor, and since it easily scatters, the workability and handleability are also poor. It also has the drawbacks of high porosity and low packing density. Further, even when it is recycled or reused, it easily scatters and the shape retention is poor, so that there is a problem that the reproducibility of void ratio and packing density is poor. Therefore, if the gas or liquid to be purified is allowed to flow through the fibrous activated carbon 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, if the gas or liquid to be purified is passed through a fluidized bed of fibrous activated carbon filled with fibrous activated carbon to adsorb and remove various molecules of harmful substances, the flocculated fibrous body will be shaped fibrous. However, it causes scattering, scattering, wear, and crushing loss, and also causes a reduction in adsorption removal rate, a reduction in treatment amount, and so-called adsorption efficiency. 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 outer surface area per unit weight is reduced because the content of the activated carbon fiber is low. In addition, 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 functionality of activated carbon has been improved against the backdrop of social excitement such as creation of amenity space such as countermeasures against groundwater pollution problems such as trichlorethylene, tap water trihalomethane countermeasures, freon gas countermeasures, deodorization, deodorization, and comfort. Improvement and improvement of shape are 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, and have high adsorption power, high adsorption / desorption rate, and good handling property. The object of the present invention is to provide a method for producing highly functional fibrous activated carbon which has good shape retention and is easy to recycle.

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors have performed spinning, infusibilization, and pre-carbonization using tar pitch as a raw material, and then the pre-carbonized fibers have a spherical shape. It was found that a highly functionalized spherical fiber lump activated carbon can be obtained by activating the carbonized carbon fiber lump to obtain a spherical pre-carbonized fibrous lump, and completed the present invention.

That is, the present invention is to prepare a pitch for spinning using tar pitch as a raw material, melt-spin this pitch for spinning, infusibilize it in an oxidizing atmosphere, and then pre-carbonize it in an inert atmosphere to obtain the pre-carbonized material. The present invention relates to a method for producing a spherical fiber lump activated carbon, which comprises subjecting a fiber to a spheroidizing treatment and then performing an activating treatment.

(Operation) 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 tar pitch. this is,
This is because the activation yield is higher when tar pitch is used as a raw material than when polyacrylonitrile-based, phenolic resin-based, cellulose-based, or the like is used. Further, the tar pitch used here is suitably one having a high softening point that is appropriately heavy so as to be suitable for spinning in the subsequent step, infusibilization, and carbonization, and has a softening point of 200 ° C. or higher. Those are preferable.

Pitch spinning can be performed by a known method,
For example, methods such as melt extrusion spinning and centrifugal spinning can be adopted.

Then, in the infusibilizing step, an oxidation treatment is performed in order to maintain the shape of the pitch fiber obtained by spinning,
For example, it is performed at a temperature of about 150 to 350 ° C. in an oxidizing atmosphere.

In the present invention, a pre-carbonization treatment is carried out in order to have strength as a carbon fiber, but the pre-carbonization here is not a usual carbonization treatment of 800 ° C. or higher, but a mild carbonization treatment of 700 ° C. or lower. That is. That is, when carbonizing the infusible fiber, carbon fiber in a temperature range of 500 ° C. or higher and 700 ° C. or higher gives a carbon fiber which is extremely flexible and has a high elongation (Japanese Patent Laid-Open No. 62-69826). This specific state is shown in FIG. 1 as the relationship between the carbonization temperature and the elongation of the carbon fiber. As a result, the subsequent spheroidization and crushing and pulverization of the fibers in the activation step are suppressed, so that the total yield is improved. Further, as a feature of the present invention, since the pre-carbonized fiber is not completely carbonized, it has an advantage that the activation process in the final step can be easily performed as compared with the ordinary carbonized fiber.

Next, the pre-carbonized fiber is spheroidized.As this method, for example, a method is proposed in which a short fiber aggregate of carbon fibers is mixed in a cylindrical container in which a swirling airflow is generated and swirled together with the airflow. (Japanese Patent Application Laid-Open No. 62-114636), this method can also be used in the present invention.

As the activation treatment method in the final step, normal steam,
A gas activation method using carbon dioxide gas, oxygen, air or the like can be adopted. Alternatively, chemical activation can also be applied. In the case of normal gas activation, the characteristics of the activated carbon fiber are controlled by the temperature of activation treatment, time, etc., but in the present invention, the degree of preliminary carbonization is changed by changing the preliminary carbonization temperature, that is, the residual rate of organic matter in the fiber. It is also possible to control the pore size, pore distribution, and specific surface area of the fibrous activated carbon as the final product by changing the activation modification of the fiber. In the case of gas activation, the activation conditions are preferably an activation temperature of 700 to 1000 ° C. and an activation time of 0 to 240 minutes. However, it is necessary to select the conditions according to the required characteristics. That is, in order to obtain a fibrous activated carbon having a wide pore size distribution and having a large average pore radius, it is preferable to treat at a high temperature for a short time,
On the other hand, in order to obtain a fibrous activated carbon having a narrow pore size distribution and a small average pore radius, it is preferable to perform the treatment at a low temperature for a long time. Further, as the activation device, a batch type or in the present invention, since the fibers are spheroidized and have good handleability, a continuous type activation furnace can also be adopted, and a known device can be appropriately selected and used. You can

The production method according to the steps of the present invention described above can produce spherical fiber lump activated carbon with high productivity and high yield because of the ease of activation treatment and the excellent handleability.

The spherical fiber lump activated carbon obtained as described above has a large outer surface area per unit weight, has a high adsorption / desorption rate, and is spherical, which is excellent in workability and handleability.
It can be filled in any shape and can be densely packed. Further, since the shape retainability is good, there is little regeneration loss and the recycling is easy. Furthermore, by utilizing 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 to obtain pitches having a trace amount of benzene insoluble matter (BI) of 57% and quinoline insoluble matter (QI). The viscosity of this pitch is 100 pois at 298 ° C.
e, and the softening point was 240 ° C. Also, under a polarizing microscope
When observed at 400 times, the entire surface had a uniform pitch showing optical isotropy.

Next, melt extrusion is performed at this pitch, and the fiber diameter is
20 μm pitch fiber was obtained and heated to 310 ° C. in air to obtain infusible fiber.

Next, this infusible fiber was preheated by heating to 600 ° C. in a nitrogen atmosphere using a batch type carbonization furnace.

After pre-carbonization, this fiber was cut into a length of 6 mm to form a chop, which was then inserted into a cylindrical container and swirled while generating a swirling air flow, whereby spherical pre-carbonized fibers could be obtained.

Next, the batch heating furnace was heated while flowing nitrogen gas containing 33% of steam, and the spherical pre-carbonized fibers were held at 800 ° C. for 4 hours in the furnace to carry out an activation treatment. It was

The yield of the obtained activated fiber is 50%, and the specific surface area (measured by Micromeritics, Asap 2000 and analyzed by Langmuir method) 1500 m ² / g, fiber diameter 16 μ
m and a fiber strength of 28 kg / mm ² . Also,
The average pore diameter was 14Å, and the volume ratio of the pore diameter of 10Å or less by the t-plot method was 80%.

Example 2 The infusible fiber obtained in Example 1 was subjected to a batch carbonization furnace,
After preheated to 600 ° C. in nitrogen to perform pre-carbonization, it was similarly spheroidized in a swirling air flow to obtain spherical pre-carbonized fibers.

Then, nitrogen gas containing 33% of water vapor is circulated in the atmosphere to raise the temperature, and the spherical pre-carbonized fibers are heated to 900
The activation treatment was carried out by holding at 30 ° C. for 30 minutes.

The yield of activated fiber obtained was 32% and the specific surface area was 20%.
The activated carbon fiber had a fiber diameter of 00 m ² / g, a fiber diameter of 15 μm, and a fiber strength of 25 kg / mm ² . Further, the average pore diameter was 17Å, and the volume ratio of pore diameters of 10Å or less was 65%.

Example 3 The infusible fiber obtained in Example 1 was subjected to a batch carbonization furnace,
After the temperature was raised to 700 ° C. in nitrogen to carry out preliminary carbonization, it was spheroidized in the same manner as in Example 1, and nitrogen gas containing 33% steam was circulated in the atmosphere to raise the temperature. An activation treatment was performed by holding the pre-carbonized fiber at 800 ° C. for 4 hours.

The yield of activated fiber obtained was 55%, and the specific surface area was 12
The activated carbon fiber had a fiber diameter of 00 m ² / g, a fiber diameter of 17 μm, and a fiber strength of 32 kg / mm ² . In addition, the average pore diameter was 12Å and the volume ratio of pore diameters of 10Å or less was 90%.

(Effects of the Invention) As described above, the method of the present invention enables efficient production of spherical fiber lump activated carbon from coal tar pitch as a raw material. That is, the production method according to the process of the present invention can produce the spherical fiber lump activated carbon with high productivity and high yield because of the ease of activation treatment and the excellent handling property. Moreover, this spherical fibrous 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. Easy and with improved functionality.

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

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the carbonization temperature and the tensile strength of carbon fibers.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kozo Yumidate 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Mamoru Kamisha 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. (56) Reference JP-A-2-255516 (JP, A) JP-A-62-59826 (JP, A) JP-A-62-114636 (JP, A)

Claims (1)

(57) [Claims] 1. A pre-carbonized fiber obtained by preparing a pitch for spinning using tar pitch as a raw material, melt-spinning the pitch for spinning, making it infusible in an oxidizing atmosphere, and then pre-carbonizing it in an inert atmosphere. A method for producing a spherical fiber lump activated carbon, which comprises activating a spheroidizing treatment after performing a spheroidizing treatment.