JPH0629436B2 - Method for producing mesocarbon microbeads - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Use The present invention relates to optically anisotropic microspheres produced by heat treatment of heavy oil such as coal tar pitch or petroleum heavy oil pitch. The present invention relates to a method for producing spherical mesocarbon microbeads from a pitch containing mesophases, and particularly to a method for producing spherical mesocarbon microbeads having a smooth surface.

(b) Prior art Heavy oils such as Pitch from which insoluble solids have been removed are added to 350 to 5
When heat-treated at 00 ° C., optically anisotropic mesophase microspheres are produced in the process of polymerizing low-molecular weight components. This small sphere mesophase has a highly polycondensed structure and is a kind of liquid product that is chemically, electrically and magnetically active and has high chemical resistance.It is a new material not found in conventional carbon materials. Attention has been paid to, for example, catalyst carriers,
It is expected to be used as a carbon material having a high added value such as a gas carrier, various adsorbents and carbon for electric resistance.

Conventionally, as a method for producing mesocarbon microbeads isolated from a matrix stick, a heavy oil is heat-treated to obtain a raw material pitch composed of mesophase microspheres and a matrix pitch, and the raw material pitch is melted by the matrix stick. Mixed with a solvent that does not dissolve mesophase microspheres,
A mixed solution of a solvent solution of matrix matrix and mesophase microspheres is obtained, and the mixed solution is subjected to a liquid cyclone to separate a solvent and a heavy liquid containing most of the mesophase microspheres,
A method has been proposed in which the solvent is removed from the heavy liquid to recover the mesophase microspheres as mesocarbon microbeads (see Japanese Patent Publication No. 58-54081).

This method is one of the so-called solvent fractionation methods.However, in the case of the solvent fractionation method known so far, especially in the case of coal-based pits, foreign substances are attached to the surface of the obtained mesocarbon microbeads. In addition, cracks are generated on the surface, and it is difficult to take out the smooth surface type mesocarbon microbeads, which often results in a limited range of use.

(c) Problems to be Solved by the Invention According to the findings of the quality of the present invention and the like, such a problem is that when a mesophase-containing pitch is soaked in a solvent for a long period of time, the solvent power of the solvent causes the mesophase microspheres to dissolve. When the matrix is formed, the matrix matrix incorporated in the sphere is dissolved, cracks are generated on the surface of the mesocarbon microbeads, and sometimes they are destroyed.Smooth mesocarbon microbeads are difficult to take out, and contact with the solvent is difficult. It is considered that when the length is too short, the solvent of the matrix stick does not progress and the matrix stick tends to adhere to the surface of the mesocarbon microbeads.

(d) Means for Solving the Problems Therefore, the inventors of the present invention have repeatedly studied to overcome such problems and obtain mesocarbon microbeads having a surface as smooth as possible. The mesophase microspheres released from the matrix matrix by dissolving in the solvent are removed from the fresh solvent as soon as possible, and the matrix with reduced solubility in the matrix matrix in the mesophase microspheres. The present invention has been achieved by finding that the above problems can be remarkably ameliorated by allowing the glutinous pulp to settle in a solvent solution.

The object of the present invention is to industrially produce mesocarbon microbeads having a smooth surface. Therefore, the object of the present invention is to obtain a mesophase microsphere obtained by heat treatment of heavy oil. Introducing a raw material pitch consisting of a matrix matrix, a solvent in which the matrix matrix is soluble but not in the mesophase microspheres, into a cleaning tank composed of a material whose bottom has an opening through which the mesophase microspheres can pass. After washing, at least a part of the mesophase microspheres in the washing tank is led through the material to a sedimentation tank provided downstream of the washing tank to cause sedimentation, and the mesophase microspheres concentrated from the lower part of the sedimentation tank. Continuously or intermittently withdrawing the dispersion liquid, and continuously or intermittently withdrawing the dispersion liquid, and separating mesophase microspheres from the dispersion liquid to obtain mesocarbon microbeads. It is readily accomplished Te cowpea to recover Te.

Hereinafter, the present invention will be described in detail.

As the mesophase microsphere-containing pits used in the present invention, various known ones can be mentioned. Specifically, coal tar pits such as coal tar pits and coal liquefaction from which the insoluble solids have been removed by removing the light oil component of coal tar, or the pits obtained by heat treating distillation residue oil in petroleum refining Petroleum-based pitches such as.

In the present invention, an optically anisotropic mesophase microsphere-containing pitch (raw material pitch) obtained by heat-treating the above-mentioned pitches according to a well-known method is used, and the mesophase microsphere content is 20 wt%. As described above, it is desirable to use a pitch having a content as high as possible, preferably 40 wt% or more, and a pitch having the same quinoline insoluble content as the spherulite concentration (determined from a polarization micrograph) is desirable.

Any solvent may be used as long as it dissolves the matrix matrix but does not dissolve the mesophase microspheres. Specifically, aromatic oils such as quinoline, pyridine, creosote oil, anthracene oil and mixed oils thereof are used. However, quinoline is preferably used. If other solvents are used, the quinoline is 20-150 ° C, preferably 20-5.
It is preferable to adjust the temperature so that the solution has a dissolving power for the pitch corresponding to 0 ° C.

By the way, the solubilizing power of quinoline to the mesophase microsphere-containing pitch used in the examples was 70% at 50 ° C., and the solubilizing power of other solvents corresponding to this was about 13% for creosote oil.
0 ° C., 1: 1 mixed oil of anthracene + creosote oil is about 80 ° C.

The amount of solvent used is 5 to 1 with respect to the raw material pitch supplied.
It may be appropriately selected from the range of 100 times by weight, preferably 10 to 20 times by weight depending on the case.

If the heating temperature is too high, the surface of the recovered mesocarbon microbeads will be cracked, and if it is too low, the dissolution rate will decrease and the processing capacity will decrease, so the temperature condition is room temperature to 150 ° C, preferably room temperature to 100 ° C. It may be selected from the range of ° C in consideration of the above factors.

In the present invention, when the raw material pitch is brought into contact with the solvent in the cleaning tank in a solvent, it is possible to introduce the raw material pitch in a molten state, but it is a solid, particularly a particle size of 1 to 10 mm, more preferably 1
If it is introduced as a small solid of about 5 mm and placed on the material at the bottom of the cleaning tank, the mesocarbon microbeads in the raw material pitch will be exposed as the matrix pitch dissolves and will then become free and free from the material. From the opening
Since it settles and descends, it is most suitable because the mesocarbon microbeads and the solvent can be appropriately contacted for a short time in the flat field.

Therefore, as the above-mentioned material, various materials may be adopted as long as the raw material pitch particles are placed, but the mesocarbon microbead particles have an opening and a structure such that they can freely pass through, but the most simple one can be adopted. A wire mesh with an opening of 0.5 to 3 mm is sufficient. It should be noted that from this material, in preparation for the case where the raw material pitch, which has been gradually melted into fine particles, falls and sufficient melting is not achieved, at least one other small opening with a smaller opening is provided below the appropriate interval. It is more preferable to install a material or a screen.

As the second material, a wire mesh having an opening of about 0.1 to 0.5 mm is preferably used.

In the present invention, it is of course possible to configure the cleaning tank and the sedimentation tank as separate devices and zones, but the most preferred embodiment of the present invention is that the cleaning tank and the sedimentation tank are in contact with the material as a boundary,
In the settling tank, the solvent solution in which a considerable amount of matrix matrix has already been dissolved and the precipitated mesocarbon microbeads are present under the condition of standing as much as possible.
A second material having a smaller opening is installed, a small-sized solid raw material pitch and a solvent are continuously or intermittently supplied to the cleaning tank, and the raw material pitch is placed on the material, and in the cleaning tank,
In particular, the mesocarbon microbeads settled from the lower part of the sedimentation tank and the solvent solution are placed separately or under a relatively gentle flow condition of the liquid so that the vicinity of the material does not disturb the standing state in the lowering tank. At the same time, it is configured to be taken out continuously or intermittently.

Various known methods can be adopted as the method for forming the liquid flow conditions near the material below the cleaning tank, such as slow and / or intermittent mechanical stirring and gas blowing stirring. , Ultrasonic irradiation or a combination of two or more of them,
It is also possible to use a local heating method together with such a flow method.

The degree of this flow condition is difficult to specify precisely, but the pitch concentration in the solution in the washing tank and the solution in the settling tank should be about the same, that is, the violence that approaches uniform stirring should be avoided. There is at least a difference in the solution concentrations in both tanks, and more preferably, a mode in which the standing condition is maintained such that the concentration increases from the upper side to the lower side even in the settling tank is selected.

The average residence time of the mesocarbon microbeads in the settling tank varies depending on the concentration of the solution, but is generally 5 to 12
It may be selected from the range of 0 minutes, more preferably about 30 to 60 minutes.

The mesocarbon microbeads thus taken out of the settling tank along with the solution are separated by using a precision material such as a microbore filter that does not pass mesocarbon,
Preferably, washed with an organic solvent such as toluene or acetone,
Get dried.

The present invention is naturally applicable to both batch processing and continuous processing.

(e) As a result, according to the method of the present invention, extremely smooth spherical particles of mesocarbon microbeads having almost no deposits or cracks on the surface can be produced by an extremely simple equipment and operation. Mesocarbon is expected to greatly open the way to applications in fields that require material surface properties as much as possible. It is also possible to obtain mesocarbon microbeads having a desired spherical diameter of approximately a certain value or less, very simply by appropriately selecting the openings of the lowermost material.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to the following examples unless it exceeds the gist.

Example A wire mesh having a mesh of 1 mm is horizontally installed as a material at approximately the middle position of a vertically long tank, the upper part thereof is configured as a cleaning tank and the lower part is configured as a settling tank. At the position of 3, a wire mesh with openings of 250 microns was installed as the second material.

The spherulite concentration measured from the polarization micrograph is 45% by weight,
A quantity of crushed mesophase microsphere-containing pitch having a quinoline insoluble content of 32% by weight was crushed to about 4 to 5 mm and placed on a wire net of material, and 100 parts by weight of quinoline was supplied to the pit to prepare a solution. The surface was completely immersed in the pits, and the pits were filled so that a slight liquid space existed, and the matrix pits in the pits were melted at the predetermined temperature and the predetermined method shown in Table 1. Then, at a predetermined time, about 30 ml of the mixture of the solvent solution of matrix matrix and the mesophase microspheres that had settled via the second material was extracted from the lower outlet of the sedimentation tank, and the same volume of quinoline was added to the cleaning tank. The extracted mixture is passed through a 10 μm Millipore filter, thoroughly washed with toluene and acetone, and then dried. This operation was repeated several times, the resulting mesophase microspheres,
Yield (% by weight) for pitch containing mesophase microspheres
The results are shown in Table 1.

The surface condition of the particles was observed by a scanning electron micrograph. As a result, on average, the surface was extremely smooth, spherical, and almost no cracking was observed.

As shown in Table 1, the fluidization of the liquid in the vicinity of the material in the cleaning tank was carried out by four methods of blowing nitrogen gas, vibrating the material with a vibrator, and imparting mechanical slow stirring ultrasonic vibration with a stirring blade. , Care was taken to keep the settling tank as static as possible. For reference, microscopic photographs of mesocarbon microbeads obtained in the case of vibrator vibration are attached as reference photograph 1 and reference magnification 2 at a magnification of 30 times, but the state is also the same in other fluidization methods. It was almost the same.

Comparative Example The same mesophase microsphere-containing pitch as in Example was placed in a container except the upper and lower wire nets of the apparatus used in Example, and the four flow conditions used in Example were applied to the entire contents, and 25 ° C.
The matrix matrix was dissolved in 30 minutes. Then, the entire contents were extracted and washed, dried and dried in the same manner as in the examples. The yields of the obtained mesocarbon microbeads were not much different from those of the examples, but the particle state was such that a large amount of pitch residue was attached to the surface and large cracks were observed. For reference, a micrograph of the vibration of the vibrator is attached as Reference Photo 3.

Claims (5)

[Claims] 1. A raw material pitch comprising mesophase microspheres obtained by heating a heavy oil and a matrix pitch, and
The matrix matrix is dissolved, but the mesophase microspheres are not dissolved, and a solvent is introduced into a cleaning tank composed of a material having a bottom surface having an opening through which the mesophase microspheres can pass, followed by cleaning, and then in the cleaning tank. Of at least a part of the mesophase microspheres are led through the above-mentioned material to a sedimentation tank provided downstream of the washing tank to cause sedimentation, and the concentrated dispersion of the mesophase microspheres is continuously or intermittently supplied from the lower part of the sedimentation tank. A method for producing mesocarbon microbeads, which is characterized in that the mesophase microspheres are separated from the dispersion and recovered as mesocarbon microbeads. 2. The method for producing mesocarbon microbeads according to claim 1, wherein the raw material pitch is introduced into a washing tank as a solid having a particle size of 1 to 10 mm. 3. The temperature of the washing tank is maintained at 20 to 150 ° C., and the temperature of the sedimentation tank is maintained at 20 to 100 ° C., respectively. ) The method for producing mesocarbon microbeads according to the above item. 4. The method for producing mesocarbon microbeads according to any one of claims (1) to (3), characterized in that an inert gas is blown into the cleaning tank. 5. A mechanical vibration or an ultrasonic vibration is applied to the contents of the cleaning tank.
The method for producing mesocarbon microbeads according to any one of items (1) to (3).