JPS62138585A - Production of mesocarbon microbeads - Google Patents

Abstract

PURPOSE:To obtain in simple operations the titled beads of good surface smoothness, useful for catalyst carrier, etc., by solvent treatment of a raw material comprising mesophase microbeads and matrix pitch to effect sedimentation of the microbeads followed by passing a liquid to separate and recover said microbeads. CONSTITUTION:(A) A raw material pitch comprising mesophase microbeads and matrix pitch, prepared by treatment of heavy oil on heating and (B) a solvent soluble for the matrix pitch but insoluble for the mesophase microbeads are put into a rinsing tank with its bottom constituted with a filter having openings passable for said microbeads to carry out rinsing. Next, either part or all of the microbeads in the above tank is introduced, through said filter, into the sedimentation tank provided downstream to effect sedimentation. The sedimented slurry of the resultant concentrated mesophase microbeads is drawn out either continuously or intermittently through the bottom of the sedimentation tank followed by passing a liquid for separation through this slurry under such conditions that said microbeads are not to be discharged, thus obtaining the objective mesocarbon microbeads.

Description

Detailed Description of the Invention (Industrial Application!!?) The present invention relates to a method for preparing spherical mesocarbon microbeads from coal tar pitch or pitch containing petroleum-based heavy substances.

In particular, the present invention relates to a method for producing microspherical mencarbon microbeads with smooth surfaces.

(Prior art) Heavy oils such as pitch from which insoluble solids have been removed 3! ;0-
When heat treated at 600℃, low molecular weight components become polymerized, and by selecting the raw materials and heat treatment conditions, s
An optically anisotropic small spherical mesophase with a sphere diameter of ~-00μ is produced.

These small spherical mesophases have structures in which highly polycondensed polycyclic aromatic hydrocarbons are arranged in a certain direction, and the carbon microbeads, which are separated from the pitch matrix using a liquid crystal, are chemically, electrically, and It is attracting attention as a new material that is magnetically active and has high chemical resistance, which is not found in conventional carbon materials. For example, it is expected to be used as a carbon material that is likely to have high added value, such as high-speed liquid chromatography carriers, catalyst carriers, gas chromatography carriers, various mild adsorbents, and carbon for electrical resistance. Particularly, as a high-speed liquid chromatography carrier, a particle size of approximately 30 μm is desirable, and therefore, such microspherical carbon microbeads are highly desired as a new material for that use.

As a conventional method for producing mesocarbon microbeads from matrix pitch, a raw material pitch consisting of mesophase small spheres and matrix pitch is obtained by heat-treating heavy oil, and the matrix pitch dissolves the raw material pitch. Mesophase spherules are mixed with a solvent that does not dissolve them.

A mixture of a solvent solution of matrix pitch and mesophase spherules is obtained, and the mixture is subjected to a hydrocyclone to separate the solvent and a heavy liquid containing most of the mesophase spherules,
A method has been proposed in which the solvent is removed from the heavy liquid and the mesophase spherules are recovered as mesocarbon microbeads (see Japanese Patent Publication No. 5G-54tort).

This method is a type of so-called solvent fractionation method, but in general, the specifics of the solvent fractionation methods known so far generally cause adhesion and cracks to occur on the surface. In the case of microsphere diameters of r-JOμ, these tendencies are remarkable, and the removal of men carbon microbeads with smooth surfaces is difficult, which often limits the range of their use. There were consequences.

(Problems to be Solved by the Invention) According to the findings of the present inventors, generally speaking, when mesophase-containing pitch is immersed in a solvent for a long time, the mesophase becomes small due to the solvent's dissolving power. During the formation of the sphere, the matrix pitch incorporated into the sphere is dissolved, and cracks occur on the surface of the mesocarbon microbeads.The mesocarbon microbeads are destroyed at one time, and the mesocarbon microbeads, which have a smooth surface, cannot be taken out. It is also believed that this is because if the contact with the solvent is too short, the dissolution of the matrix pitch does not progress, and the matrix pitch tends to adhere to the surface of the mesocarbon microbeads.

Moreover, again. It is believed that this is due to the fact that when the mesocarbon microbeads and the pitch matrix are separated from each other, the matrix pitch and fine particles such as quinolinine dissolved in the matrix pitch re-adhere to the surface of the fiIVC mekkapeas.

(Means for Solving the Problems) Therefore, the present inventors have attempted to overcome these problems, especially those in the case of microsphere diameter, and obtain mesocarbon microbeads with as smooth a surface as possible. After careful consideration, we found that by dissolving mesophase-containing pitch in a solvent, it was possible to precipitate the mesophase-containing pitch in a solvent solution that had a reduced dissolving power for IJ spherules in the matrix bead spherules. Furthermore, it is believed that the above-mentioned problems can be greatly improved by passing a separating liquid through this sedimentation slurry and removing it from the mesophase spherules and other components in the sedimentation slurry as quickly as possible. This discovery led to the present invention.

The purpose of the present invention is to produce carbon microbeads with smooth surfaces in a certain technical advantage.
The purpose of the present invention is to combine a raw material pitch consisting of mesophase spherules and matrix pitch obtained by heat-treating heavy oil, and a solvent that dissolves the matrix pitch but does not dissolve the mesophase spherules in the bottom surface. The mesophase spherules are cleansed by cleaning them in a cleaning tank made of F material with an opening through which they can flow, and at least some of the men's 7 works of the bond A are removed. The spheres are led through the door material to a sedimentation tank provided downstream of the washing tank and allowed to settle, and a sedimented slurry of mesophase spherules concentrated at the bottom of the sedimentation tank is continuously or intermittently drawn out. This can be easily achieved by separating and recovering the mesophase spherules from the sedimentation slurry (by passing a separation liquid through the sedimentation slurry under conditions such that the mesophase spherules do not flow out).

The present invention will be explained in detail below.

Various known pitches containing mesophase small spheres can be used in the present invention. Specifically, we heat-treat coal-based pitches such as Co/I/tar pitch and coal liquefied products from which the light oil content of coal tar has been removed, filtered, etc., and insoluble solids have been removed, or distillation residue oil from petroleum refining. Petroleum-based pitches such as pitch obtained by

In the present invention, a dimensionally anisotropic mesophase small sphere-containing pitch (raw material pitch) obtained by heat-treating the above pitches according to a well-known method is used, and the content of mesophase small spheres is 10'wt. % or more, preferably *(7
It is desirable to use a pitch with as much content as possible, WtX or more, and a pitch in which the 1-spherulite strength (determined from a polarized light micrograph) and the quinolinated content are equal.

When extracting mesocarbon micropeas from the raw material pitch obtained in this way using a sludge fractionation method.

In addition to this, it is necessary to take into account the composition of the raw material pitch. That is, in the raw material pitch, in addition to the mesophase spherules that do not dissolve in the solvent and the pitch matrix that dissolves in the solvent, there are also mesophase spherules that are formed in the polycondensed sita matrix that is isotropic and has no anisotropy. Quinolytic components of (
Hereinafter, it will simply be referred to as an insoluble pitch component. ), and if possible, a pitch with a small content of such components is desirable, but in any case, in the present invention, the mesophase spherules are made from as much of these components as possible. It is hoped that you can leave quickly.

The solvent used for dissolving the raw material pitch may be one that dissolves I7 Tsukusubitsu but does not dissolve mesophase spherules, and specifically includes quinoline, pyridine, creosote oil, anthracene oil, and mixed oils thereof. Any aromatic oil can be used, preferably quinoline. When using other solvents, use 10 to 130 of quinoline.
It is preferable to adjust the temperature so as to have a pitch-dissolving power corresponding to 10-60°C.

By the way, the dissolving power of quinoline for the pitch containing mesophase microspheres used in the examples is DeOX at 30°C, and the equivalent dissolving power of other solvents is approximately J
The temperature of the mixed oil of anthracene and creosote oil is approximately tQ°C.

The amount of solvent used is r-i relative to the supplied raw material pitch.
It may be selected as appropriate from the range of oo times the weight, more preferably from /Q to -0 times the weight.

If the heating temperature is too high, cracks will form on the surface of the recovered mencarbon microbeads.

Ah-1! If b is low, the dissolution rate will decrease and the processing capacity will decrease, so the temperature condition is room temperature to 7! rO"Cm is preferably selected from the range of room temperature to 100°C while taking into account the above factors b0 In the present invention, it is possible to dissolve it with the raw material pitch in the cleaning tank, but the solid, especially the particle size of 7. ~10trm, yo)
Preferably, it is introduced as a small solid of about / −j m,
If introduced so as to be placed on the door 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 then become free and will settle and descend through the openings of Pu. Therefore, the contact between the Mencarbon microbeads and the solvent for a suitable short period of time is ensured on average, which is most preferable.

Therefore, the above F material may be of various types as long as it has an opening and structure that allows the raw material pitch particles to be placed but the mesocarbon microbead particles to freely pass through, but the most convenient method is A wire mesh with an opening of θ, s to Jw+ is sufficient.

In addition, in case the raw material pitch consisting of nine matrix pitches, which are successively melted into microparticles, falls from this P material and sufficient dissolution is not achieved, there are small openings (open holes) at the bottom of the P material at appropriate intervals. b It is more preferable to install at least one other Pu or screen.

This first F material is selected from o, oz to 0, depending on the diameter of the mesoface small sphere. ! A wire mesh with an opening of approximately 1.5 m is preferably used.

In the present invention, it is of course possible to configure the washing tank and settling tank as separate devices or zones.

In the most preferred embodiment of the present invention, the cleaning tank and settling tank are made of Pu.
In the settling tank, there is a solvent solution layer in which the matrix pitch has already been dissolved in a mutually self-dissolved amount and the settled mesophase small spheres. It is supplied continuously or intermittently, and the raw material pitch is F.
The inside of the cleaning tank, especially the area near the top of the door material, is placed under relatively mild flow conditions of liquid to the extent that it does not disturb the static condition in the sedimentation tank below, and the lower part of the sedimentation tank is The apparatus is configured to continuously or intermittently extract a sedimented slurry of metphase spherules and a solvent solution from the apparatus.

As mentioned above. Various known methods can be used to create liquid flow conditions near the F material below the cleaning tank. For example, slow and/or intermittent mechanical stirring,
Gas injection stirring.

It is also possible to use ultrasonic irradiation, a combination of two or more thereof, and localized heating methods in combination with such flow methods.

Although it is difficult to strictly define the degree of flow conditions, it is recommended that the pitch concentration in the bath liquid in the cleaning tank and settling tank be approximately the same, and that vigorous stirring that approaches uniform stirring should be avoided. Preferably, an embodiment is selected in which standing conditions are maintained such that there is at least a difference in the concentration of the solution in both tanks, and the concentration increases from the top to the bottom in the sedimentation tank.

The average residence time of the mesophase spherules in the sedimentation tank varies depending on the concentration of the solution, but is generally selected from the range of j--1:10 minutes, preferably from JO to lhO minutes.

Next, the sedimented slurry of Mencarbon microbeads taken out from the sedimentation tank with the solution is usually filtered door-to-door using a precision door material such as a MicroZear filter that does not allow Mencarbon to pass through. However, in the case of microspheres with a diameter of about 110 μm, it is necessary to reduce the opening of the dirt material, so the fine particles, which are insoluble pitch components in the matrix, fill the openings of the F material and filter. Even if microbeads with no deposits settle out due to the operation of the cleaning tank, deposits will form again. The present invention proposes to prevent this redeposition, most typically by appropriately selecting the specific gravity and flow rate of the separation liquid and flowing the liquid upward into the sedimentation slurry at a constant flow rate. As a result, the mesophase spherules remain or settle, while the insoluble pitch components and liquid in the settling slurry flow out of the processing zone along with the separation liquid. In this sense, it is desirable that the specific gravity of the separation liquid is smaller than that of the mesophase spherules, and specifically, the specific gravity θ,
It is preferable to select from the range of 2 to /60.

However, the present invention is not limited to the above-mentioned typical example, and also includes cases where a part of the mesophase spherules flows out or moves in the direction of outflow, and furthermore, the case where the solid is diluted by the separation foot is also included. .

If the mesophase/h spheres and other insoluble pitch components can be easily separated in the furnace, the direction of flow of the liquid for 1 minute d may be upward, downward, or horizontal; Depending on the material, it is also possible to completely block the outflow part.

Therefore, as a separating liquid, it is possible to use a liquid that does not dissolve not only the mesophase spherules but also other insoluble pitch components in the sedimentation slurry, but it is preferable that it has a mild dissolving power only for other insoluble pitch components. Examples of separation liquids used include acetone, ketones such as methyl ethyl lactone, benzene, and toluene. .

The nine mesocarbon microbeads thus separated from other components of the sedimentation slurry are taken out by themselves or together with a portion of the separation liquid, and are isolated and recovered by washing, filtration, or other operations as necessary.

The outflowing separation liquid is separated, as necessary, from the pitch-based liquid components and solid components that it contains, as well as the solvent used in the cleaning tank and sedimentation tank.

It can also be removed, recovered and reused.

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

(Effects) Thus, according to the method of the present invention, extremely smooth spherical particles with almost no deposits or cracks on the surface (with extremely simple equipment and operation) can be produced regardless of their spherical diameter. It is expected that such f-carbons will greatly open the door to applications in fields requiring as homogeneous surface characteristics as possible. Furthermore, by appropriately selecting the opening of the furnace material at the bottom of the sedimentation tank, it is possible to very easily obtain mesocarbon microbeads having a desired spherical diameter below a certain value.

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example - A wire mesh with an opening of 1 mm is installed horizontally as a furnace material at the middle position of a vertically long tank, and the upper part is a cleaning tank and the lower part is a sedimentation tank. A wire mesh made of Kudamicron with openings was installed as the No.-F material at a position about 1/3 from the top.

Measured from a polarized light micrograph, the 9-spherulite concentration is 1/, j weight is 9, quinoline solubility is 10, j weight x weight particle diameter is j
The mesophase spherule-containing pitch, which is ~30μ, is approximately
A certain amount of coarsely crushed J+W+ is placed on the wire mesh of the furnace material, and 100 parts by weight of quinoline is supplied to the pitch until the liquid level is completely immersed in the pitch and there is still some liquid space. The matrix pitch in the pitch was dissolved by stirring with a stirring blade at 3°C.

Then, every 30 minutes, the sedimentation slurry, which is a mixture of the solvent solution of the matrix pitch and the mesophase spherules, is pumped through the material No.-F to the lower outlet of the sedimentation tank.
At the same time as the wl was removed, the same amount of quinoline was added to the cleaning tank. The extracted sedimentation slurry was introduced into the intermediate position of the separation treatment tank where acetone was flowing upward at a constant flow rate of 0.96 tM/- and overflowed (from the top). Its introduction is approximately JOtd of the settling slurry.

The treatment is carried out intermittently at approximately JO minute intervals when the number of particles of insoluble pitch components suspended in the separation treatment tank decreases.

Finally, when the fine particles of the insoluble pitch component are no longer suspended in the 9-sedimentation three.

The flow of acetone was stopped, and the mesocarbon microbeads that had settled at the bottom of the separation treatment tank were filtered through a lμO Millipore filter, washed with acetone, and dried to obtain a product. The yield of the obtained mesocarbon microbeads based on the raw material pitch was -0.t weight.

In addition, when the surface condition of the particles was observed using scanning electron micrographs, it was found that the surface of the particles was perfectly spherical, with an extremely smooth surface, and almost no cracks were observed.

Note that the residue obtained by filtering the acetone over-puff liquid in the separation treatment tank with a 7 μm millibore filter was similarly observed under a microscope.

M) The insoluble pitch component in IJ Lux was in the form of a cake, and no mesocarbon microbeads were observed therein.

Example - A wire mesh with an opening of 110 microns was installed as the third material in the same configuration as in Example 1.

Measured from the polarized light micrograph, the nine-spherite concentration was 0.0! Amount
So, the quinolinol dissolved content is ko, da weight x, and its spherical diameter is go
The flow rate of acetone in the treatment tank was set to 1. Mesocarbon microbeads were obtained in the same manner as in Example 7, except that the opening of the filter for separating mesocarbon microbeads from acetone was changed to /Qμ. As a result, the yield to the raw material pitch was IIO.3 weight ratio, and the observed surface condition was.

It was smooth with almost no cracks.

Claims (4)

[Claims] (1) Mesophase spherules with bottom surfaces pass through a raw material pitch consisting of mesophase spherules and matrix pitch obtained by heat treating heavy oil, and a solvent that dissolves the matrix pitch but not the mesophase spherules. Introducing it into a cleaning tank consisting of a filter medium with possible openings,
The mesophase spherules are washed, and then at least some of the mesophase spherules in the washing tank are led out through the filter medium to a sedimentation tank provided downstream of the washing tank and allowed to settle, and the mesophase spherules are concentrated from the lower part of the sedimentation tank. The mesophase spherules are separated and recovered from the sedimentation slurry by continuously or intermittently deriving a sedimentation slurry, and passing a separation liquid through the sedimentation slurry under conditions that the mesophase spherules do not flow out. A method for producing mesocarbon microbeads. (2) The method for producing mesocarbon microbeads according to claim (1), wherein the separation liquid has a specific gravity of 0.7 to 1.0. (3) The method for producing mesocarbon microbeads according to claim (1) or (2), wherein the separation liquid is a ketone. (4) Claim (1) or (2) characterized in that the separating liquid is an aromatic hydrocarbon.
A method for producing mesocarbon microbeads as described in Section 1.