JPH0635582B2 - Method for producing mesocarbon microbeads - Google Patents

Description

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

(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, the low-molecular-weight component is polymerized into a polymer, and by selecting the raw material and heat-treatment conditions,
Optically anisotropic small spherical mesophases with a diameter of 200μ are produced.

This microsphere mesophase has a structure in which highly polycondensed polycyclic aromatic hydrocarbons are arranged in a certain direction, and it is a kind of liquid crystal, and mesocarbon microbeads separated from Pichimatrix are chemically, electrically and magnetically. It has been attracting attention as a new material that is not found in conventional carbon materials because it is highly active and has high chemical resistance. For example, high-speed liquid carrier,
It is expected to be used as a carbon material having a high added value, such as a catalyst carrier, a gas chromatographic carrier, various adsorbents, and carbon for electric resistance. Particularly, as a high-speed liquid carrier, a particle size of about 5 to 30 μm is desirable, and thus such microspherical mesocarbon microbeads are greatly demanded as a new material for its use.

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 a kind of so-called solvent fractionation method, but in the concrete method of the solvent fractionation method generally known so far, particularly in the case of coal-based pitch, solid pitch pieces are obtained on the surface of the obtained mesocarbon microbeads. In the case of a foreign matter such as, etc., or a crack on the surface, especially in the case of a microsphere having a diameter of 5 to 30 μ, these tendencies are remarkable, and it is difficult to take out the surface-shaped mesocarbon microbeads. This often results in a limited range of use.

(Problems to be Solved by the Invention) According to the findings of the present inventors, such a problem is that when a mesophase-containing pitch is soaked in a solvent for a long time, the mesophase microspheres are formed due to the dissolving power of the solvent. The matrix matrix taken up in the sphere during formation is dissolved, cracks occur on the surface of the mesocarbon microbeads, and sometimes they are destroyed, and it is difficult to take out the smooth mesocarbon microbeads, and there is not much contact with the solvent. It is considered that when the length is short, the matrix sticking does not proceed to dissolve, and the matrix sticking tends to adhere to the surface of the mesocarbon microbeads.

Furthermore, when the mesocarbon microbeads and pitimatrix are separated, especially when the mesocarbon microbeads have a small spherical diameter, the furnace material is apt to cause clogging, and thus the matrix on the surface of the mesocarbon microbeads It has been considered that this is due to redeposition of fine particles such as quinoline-insoluble matter in the pitch and the matrix.

(Means for Solving Problems) Therefore, the present inventors have overcome such problems, particularly in the case of microspheres, to obtain mesocarbon microbeads having a surface as smooth as possible. As a result of repeated studies, by dissolving the mesophase-containing pitch in a solvent, the mesophase microspheres released from the matrix matrix are removed from the new solvent as quickly as possible, and the mesophase microspheres are removed. Precipitation in a solvent solution having a low dissolving power for matrix matrix. Furthermore, it has been found that the above problems can be remarkably ameliorated by causing a separation liquid to circulate in the sedimentation slurry and separating the mesophase microspheres from other components in the sedimentation slurry as quickly as possible. The present invention has been reached.

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. A raw material pitch consisting of a matrix matrix, and a solvent in which the matrix matrix is soluble but the mesophase microspheres are not dissolved are introduced into a cleaning tank having a bottom having a flowable opening for the mesophase microspheres. After washing, at least a part of the mesophase microspheres in the cleaning tank is led out through the material to a sedimentation tank provided downstream of the cleaning tank to cause sedimentation, and the mesophase microspheres concentrated from the lower part of the sedimentation tank. Of the sedimentation slurry is continuously or intermittently introduced, and the separation liquid is circulated in the sedimentation slurry under the condition that the mesophase microspheres do not flow out. It is readily accomplished Te cowpea to separate and recover Mesofuezu spherules from rally.

Hereinafter, the present invention will be described in detail.

Various known mesophase microsphere-containing pitches may be used in the present invention. 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, but the mesophase microsphere content is 20 wt%. Or more, preferably 40 wt%
It is desirable to use pitches having the highest possible content, and it is desirable to use pitches in which the spherulite concentration (determined from a polarization micrograph) is equal to the quinoline insoluble content.

When the mesocarbon microbeads are taken out from the thus obtained raw material pitch by the solvent fractionation method, it is necessary to take into consideration the components of the other raw material pitch. That is, in the raw material pitch, with the mesophase microspheres that do not dissolve in the solvent,
In addition to Pichimatrix which dissolves in a solvent, there is a quinoline-insoluble component (hereinafter simply referred to as an insoluble Pitch component) in isotropic polycondensed matrix which is non-anisotropic and has a low degree of polycondensation. However, if possible, a pitch with a low content of such a component is desirable, but in any case, in the present invention, the mesophase microspheres can be separated from such a component as quickly as possible. Is desired.

The solvent used to dissolve the raw material pitch may be one that dissolves the matrix matrix but does not dissolve the mesophase microspheres, and specifically includes quinoline, pyridine, creosote oil, anthracene oil and mixed oils thereof. Aromatic oils can be used, but preferably quinoline is used. If other solvents are used, quinoline at 20-150 ° C,
It is preferable to adjust the temperature so that the solution has a dissolving power for the pitch of 20 to 50 ° C.

By the way, the solubilizing power of quinoline to the mesophase microsphere-containing pitch used in the examples was 90% 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, more 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 and the solvent are brought into contact with each other in the cleaning tank, the raw material pitch can be introduced in a molten state, but the solid, particularly the particle size is 1 to 10 mm, more preferably about 1 to 5 mm. Introduced as a small solid, if introduced so as to be placed on the material at the bottom of the cleaning tank, the mesocarbon microbeads in the raw material pitch are exposed as the matrix matrix is dissolved, and then become free and through the opening of the material, Since it settles and descends, it is most suitable because the appropriate short-time contact between the mesocarbon microbeads and the solvent is ensured on average.

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, the material pitch composed of a matrix matrix which was successively melted and formed into fine particles was dropped, and in case the melting was not sufficiently achieved, a smaller opening was provided under the appropriate interval. It is more preferable to install one other material or screen.

As the second material, a wire mesh having an opening of about 0.05 to 0.5 mm depending on the diameter of the small mesophase sphere 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 been dissolved and the precipitated mesophase microspheres are present under the stationary condition as much as possible. No. 2 material is installed, the small-sized solid raw material pitch and solvent are continuously or intermittently supplied to the cleaning tank, the raw material pitch is placed on the material, and the sediment in the cleaning tank, especially near the material is set downward. It is placed under a relatively mild flow condition of a liquid that does not disturb the standing state in the tank, and continuously or intermittently withdraws the sedimented slurry of Mefaze microspheres and solvent solution that have settled from the bottom of the sedimentation tank. Composed.

As the above-mentioned method for forming the liquid flow condition in the vicinity of the material below the cleaning tank, various known methods can be adopted, for example, slow and / or intermittent mechanical stirring,
It is also possible to use gas blowing stirring, ultrasonic irradiation, a combination of two or more thereof, and 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.

Although the average residence time of the mesophase microspheres in the settling tank varies depending on the concentration of the solution, it may be generally selected from the range of 5 to 120 minutes, more preferably about 30 to 60 minutes.

Next, the sedimentation slurry of the mesocarbon microbeads thus taken out from the sedimentation tank together with the solution is usually separated by using a precision material such as a micropore filter that does not allow the mesocarbon to pass. In the case of microspheres with a sphere diameter of about 5 to 20 μm, it is necessary to reduce the opening of the material, so the fine particles of the insoluble pitch component in the matrix block the material's eyes, and the deterioration of the quality of the material deteriorates. Then, even if the microbeads having no deposit settle, the deposit will again be generated. The present invention proposes to prevent this redeposition, and most atypically, the specific gravity and flow velocity of the separating liquid are appropriately selected, and the liquid is circulated in the upward direction at a constant flow velocity in the sedimentation slurry. As a result, the mesophase microspheres stay or settle, but the insoluble pitch component and liquid in the settled slurry are made to flow out from the treatment zone together with the separating liquid. In this sense, the specific gravity of the separating liquid is preferably smaller than that of the mesophase microspheres.
It is good to select from the range of 1.0.

However, the present invention is not limited to the above-mentioned typical example, a part of the mesophase microspheres flows out, or includes a case where the mesophase microspheres move in the direction of the outflow, and further, the result that the solid is diluted with the separation liquid in a diluted manner. In the case where the mesophases, small spheres and other insoluble pitch components can be easily separated by furnace, regardless of whether the separation liquid flows in the up, down, or horizontal direction,
Moreover, it is possible to use such a material to block the outflow portion.

Therefore, as the separation liquid, not only mesophase microspheres, but also those that do not dissolve other insoluble pitch components in the sedimentation slurry can be used, but more preferably, only the other insoluble pitch components have a mild dissolving power. Examples of liquids for separation that are selected and used include acetone, ketones such as methyl ethyl ketone, benzene, toluene, or gas light oil which is a mixture of benzene, toluene, and xylene.

Thus, the mesocarbon microbeads separated from the other components of the settled slurry are taken out by themselves or together with a part of the separating liquid, and if necessary, they are isolated and recovered by washing, passing or the like.

The outflowing separation liquid may be recovered and reused by separating and removing the Pitch-based liquid components and solid components, which have been contained, and further the solvent used in the washing tank and the sedimentation tank, if necessary. it can.

Further, the present invention is naturally applicable to both batch processing and continuous processing.

(Effect) Thus, 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 with extremely simple equipment and operations regardless of the size of the spherical particles. It is expected that such mesocarbons will greatly open the way to applications in fields that require as homogeneous surface characteristics as possible. It is also possible to obtain a very simple mesocarbon microbeads having a desired spherical diameter of less than a fixed position by appropriately selecting the mesh size of the material at the bottom of the settling tank.

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 1 A wire net with an opening of 1 mm was horizontally installed as a material at approximately the middle position of a vertically long tank, and the upper part thereof was constituted as a washing tank and the lower part was constituted as a sedimentation tank. A wire mesh with an opening of 74 microns was installed as a second material at a position of about 1/3.

The spherulite concentration measured from the polarization micrograph is 21.5% by weight,
A quantifying amount of a mesophase microsphere-containing pitch having a quinoline insoluble content of 20.5% by weight and a sphere diameter of 5 to 30 μ was roughly crushed to about 4 to 5 mm, and placed on a wire mesh to obtain 100 parts by weight of the pitch. Of the quinoline of Example 1 was supplied so that the liquid surface was completely immersed in the pit, and the pit was filled so that some liquid space existed. The stirring blade stirring was performed at 25 ° C. to dissolve the matrix paste in the pit. Then, about 30 ml of the settled slurry, which is a mixture of the solvent solution of matrix matrix and mesophase microspheres settled via the second material every about 30 minutes, is withdrawn from the lower outlet of the settling tank in an amount of about 30 ml, and the same volume of quinoline is washed in the washing tank. Added to. The sedimented slurry extracted is
Acetone flowed upward at a constant flow rate of 0.96 cm / min, and was introduced into the separation treatment tank at an almost intermediate position where it overflowed from the upper part. The introduction is about 30 ml of sedimentation slurry
Was carried out intermittently at a time point when the floating of fine particles of the insoluble pitch component in the separation treatment tank decreased, that is, at intervals of about 30 minutes.

At the time when the fine particles of the insoluble pitch component were no longer suspended in the last settling slurry supplied, the flow of acetone was stopped, and the mesocarbon microbeads that had settled to the bottom of the separation treatment tank were passed through a 1μ Millipore filter and washed with acetone. After drying, a product was obtained. The yield of the obtained mesocarbon microbeads based on the raw material pitch was 20.9% by weight.

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.

In addition, when the residue obtained by passing the acetone overflow solution in the separation treatment tank with a 1 μm Millipore filter was observed under a microscope in the same manner, the insoluble pitch component in the matrix was in the form of caking. No microbeads were found.

Example-2 In the same structure as in Example-1, a wire mesh having openings of 150 microns was installed as the second material. Spherulite concentration measured from polarized light micrograph is 40.0 wt% and quinoline insoluble matter is 12.4
Pitches containing mesophase microspheres having a diameter of 50 to 100 μm in weight% were set to a flow rate of acetone of 1.20 cm / min in a separation treatment tank, and a separation filter for separating mesocarbon microbeads from acetone was opened to 10 μm. Mesocarbon microbeads were obtained in the same manner as in Example 1 except that As a result, the yield with respect to the raw material pitch was 40.3% by weight, and the surface condition observed was smooth with almost no cracks.

Claims (4)

[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 material to a sedimentation tank provided downstream of the washing tank to cause sedimentation, and the sedimented slurry of the mesophase microspheres concentrated from the lower part of the sedimentation tank is continuously or intermittently supplied. Method for producing mesocarbon microbeads, characterized in that the mesophase microspheres are separated and recovered from the sedimentation slurry by circulating a separation liquid under conditions where the mesophase microspheres do not flow into the sedimentation slurry. . 2. The method for producing mesocarbon microbeads according to claim 1, wherein the specific gravity of the separating liquid is 0.7 to 1.0. 3. The method for producing mesocarbon microbeads according to claim (1) or (2), wherein the separating liquid is a ketone. 4. The separation liquid according to claim 1, wherein the separation liquid is an aromatic hydrocarbon.
The method for producing mesocarbon microbeads according to the item.