JPH0635579B2 - Method for producing pitch containing microsphere-shaped mesophase - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an optically anisotropic small spherical mesophase produced by heat treatment of a heavy oil such as coal tar pitch or petroleum-based pitch. The present invention relates to a method for producing a pitch containing a large amount of mesophase pitch.

TECHNICAL FIELD The present invention relates to a method for producing a microsphere-shaped mesophase-containing pitch, and more specifically to a pitch containing a higher concentration of the mesophase, and thus to a method for efficiently producing the mesophase from the pitch. It is related. Generally, when heat treatment is performed on the pitches from which insoluble solids have been removed at 350 to 500 ° C., optically anisotropic mesophases are produced in the process in which low molecular weight components in the pitch become high in molecular weight.

This mesophase is a kind of liquid crystal that has a structure in which highly condensed polycyclic aromatic hydrocarbons are aligned in a certain direction.
It is attracting attention as a new material that is not found in conventional carbonaceous materials because it is electrically and magnetically active and has high chemical resistance.
Furthermore, it is known that this mesophase component changes into a microsphere under a certain condition. Pitches containing a high concentration of these small spherical mesophases are used as a binder for high-grade carbon materials such as high-density molded carbon materials and as substitutes for aggregates.
Further, small spherical mesophases separated from the pitch by solvent fractionation, that is, mesocarbon microbeads are used as a carbon material having a high added value such as a catalyst carrier, a chromatogram adsorbent, and an electric resistance carbon. It is expected to be used in a wide range.

Prior art However, when the heat treatment of the Pitches is carried out in order to obtain such small spherical mesophases, the ratio of the obtained small spherical mesophases is generally around 20%. The spherical diameter of the small spheres increases, and further changes to flow pattern-like bulk mesophases, and the small spherical mesophases disappear. Therefore, it is difficult to generate a high concentration of small spherical mesophases only by heat treatment. As one means to solve this point, the present applicant has proposed a method of producing a spherical mesophase at a relatively high concentration by subjecting the previously heat-treated pitch to a reduced pressure treatment under a heating and melting condition. (Japanese Patent Laid-Open No. 58-93786) Problems to be Solved by the Invention Although this method is extremely effective in terms of high-concentration production, the spherical diameter of the small spherical mesophases produced by merely reducing the pressure is relatively small. A tendency was found that it was difficult to be uniform.

Means for Solving the Problems Therefore, the inventors of the present invention have conducted further studies, and as a result, by the extremely simple treatment of adding a viscosity reducing agent to the pitch at the pressure reduction treatment stage, the small spheres having a relatively uniform particle size are obtained. The present invention has been accomplished by finding that it is possible to generate mesophases in a high concentration.

That is, the gist of the present invention is to heat-treat heavy oil from which insoluble solids have been removed to form mesophases, and then subject the mesophase-containing pitch to depressurization under melting conditions to convert the mesophases into small spheres. And a method for producing a microsphere-containing pitch containing mesophases, which comprises adding a viscosity reducing agent to the pitch containing mesophases.

Operation The present invention will be described in detail below.

As the pitches used in the present invention, various known ones can be mentioned. Specifically, by removing light components from coal tar and removing insoluble solids by means such as oversedimentation separation, coal-based pits such as coal tar pits and coal liquefaction or distillate residual oil in petroleum refining is heat treated. Examples include petroleum-based pitches such as the obtained pitches.

In the present invention, first, the above-mentioned pits are heat-treated to generate optically anisotropic mesophases. At that time, the proportion of the generated mesophases is usually 20% or more, preferably 30 to 90%. To heat. The heat treatment conditions vary depending on the raw material, but are usually 350 to 500 ° C., preferably 3
80 to 450 ° C., 0.5 to 10 hours, preferably 1 to 5
It takes place over a range of times. At that time, in order to carry out uniform heat treatment, it is preferable to employ a method of stirring, blowing an inert gas such as nitrogen gas into the pitch, or performing both of them at the same time.

Then, by such a heat treatment, the viscosity reducing agent is added to the obtained mesophase-containing pitch and the pressure reducing treatment is performed under heating and melting conditions, or the viscosity reducing agent is added in the middle of the pressure reduction treatment and the pressure is reduced. The viscosity reducer used in the present invention is compatible with the mesophase-containing pitch and does not contain insoluble solid matter, and has a viscosity of 30 times that of the mesophase-containing pitch.
% Or less, preferably 0.2 to 20%, for example, heavy tar and pitch from which light components have been removed up to 250 ° C., preferably up to 300 ° C. or mild heat treatment pitch or hydrogenated pitch. Is used. The raw materials may be either coal-based or petroleum-based, or a mixture thereof. The amount of addition is such that, at the end of the pressure reduction treatment, the temperature of the entire system is 10 poise or less, preferably 1 to 8 poise.

Specifically, for example, 1 to 2 of the viscosity reducing agent is added to the mesophase-containing pitch (anisotropy ratio of 20% or more) obtained by heat treatment.
0% added, heating and melting temperature 350 to 430 ° C., preferably 370 to 410 ° C., reduced pressure degree 100 Torr or less, preferably 10 Torr or less, particularly preferably 5 Torr or less 0.5 to
Depressurize for 30 minutes. As a result, almost all mesophases produced by the heat treatment are converted into small spherical mesophases.

If the viscosity reducing agent is added at the time of returning to normal pressure after the depressurization treatment and the viscosity is lowered to cool and precipitate spherulites,
If the viscosity reducing agent itself is too soft or the amount of addition is too large, the viscosity will be too low and the small spheres will easily settle and coalesce, and the sphere size distribution will be broader. Therefore, it is desirable to add the viscosity reducing agent before or during the pressure reduction treatment. That is, if the viscosity reducing agent is added in the depressurizing step, the light components of the viscosity reducing agent itself are also removed, and since an appropriate viscosity is maintained, sedimentation and coalescence of the small spheres does not easily occur, and the relatively small spheres have a uniform diameter. Spherical mesophases can be obtained in high concentration.

EFFECTS OF THE INVENTION The small spherical mesophases obtained by the above method can be prepared by appropriately adjusting the degree of weight of heat-treated pitch, the type of viscosity reducing agent and the addition amount of the reduced pressure treatment condition under heating and melting within the above range.
In the range of 00μ or less, the spherical diameter is relatively uniform and high concentration (4
0-70%).

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.

The concentration of the small spherical mesophases in the examples is
It is a value obtained by measuring the proportion of the small spheres from a polarization micrograph.

Example 1 Pitches (TI 7%, QI 0%) from which the insoluble solids have been removed by sedimentation separation except for the light components of coal tar were heat-treated at 405 ° C. for 7 hours by blowing N ₂ gas under stirring. The resulting mesophase-containing pitch had an anisotropy ratio of 70%, most of which had a flow pattern and a viscosity of 60 poise and 290 ° C. This mesophase-containing pitch was subjected to hydrogenation treatment of the coal tar pitch from which solid content had been removed with 2 times by weight of tetrahydroquinoline at 470 ° C. for 1 hour, and then the hydrogenated pitch (TI 22%, QI 0%, viscosity;
0.4 poise, 290 ° C) was added as a viscosity reducing agent in an amount of 10%, and a pressure reduction degree of 5 Torr was applied for 10 minutes in a molten state at 390 ° C. As a result, almost 50 to 50 flow pattern mesophases were obtained.
The microsphere-shaped mesophase was changed to 200 μ, and the microsphere-shaped mesophase concentration in the pitch was 70%. The viscosity of the pitch after the reduced pressure treatment was 3 poises at 390 ° C.

Comparative Example 1 The mesophase-containing pitch obtained by heating as in Example 1 was added at 390 ° C. 5 Torr without adding a viscosity reducing agent.
The material subjected to the reduced pressure treatment for 10 minutes partially spheroidized, but the flow pattern mesophase remained. Further, the viscosity of the pitch that left a part of this flow pattern was 20 poise at 390 ° C.

Example 2 The pitch obtained by removing the insoluble solids in the same manner as in Example 1 was heat-treated with stirring at 405 ° C. for 5 hours while blowing N ₂ gas. The obtained mesophase-containing pitch had an anisotropy ratio of 25% and had a flow pattern and a viscosity of 30 poise and 290 ° C.
It was. To this mesophase-containing pitch, a coal tar pitch from which solid matter was removed as a viscosity reducing agent was added at 380 ° C.
Pitch (TI 20%, viscosity; 1 poise, 290 ° C) was added at 10% for 1 hour and depressurized at 390 ° C for 5To
rr, reduced pressure treatment was performed for 10 minutes.

As a result, almost all of the flow pattern mesophases are 50.
The amount of microsphere-shaped mesophases changed to ˜100 μ, and the amount of microsphere-shaped mesophases in the pitch was 45%. The viscosity of the pitch after the reduced pressure treatment was 3 poises at 390 ° C.

Claims (5)

[Claims] 1. A heavy oil from which insoluble solids have been removed is subjected to heat treatment to form mesophases, and then the mesophase-containing pitch is subjected to a reduced pressure treatment under melting conditions to convert the mesophases into small spheres. A process for producing a microsphere-containing mesophase-containing pitch, which comprises adding a viscosity reducing agent to the content pitch. 2. The viscosity reducing agent does not include insoluble solid matter,
The method for producing a microsphere-containing pitch containing mesophases according to claim 1, which is compatible with the mesophase-containing pitch and has a lower viscosity than the pitch. 3. The amount of the viscosity reducing agent added is an amount such that the viscosity of the mesophase-containing pitch at the end of the depressurization treatment is 10 poise or less. A method for producing a microsphere-shaped mesophase-containing pitch as described. 4. The method for producing a microsphere-containing pitch containing mesophases according to any one of claims 1 to 3, wherein the viscosity reducing agent is added at the start of the pressure reduction treatment. 5. The method for producing microsphere-shaped mesophase-containing pitches according to any one of claims 1 to 4, wherein the mesophase-containing pitch after the heat treatment has a mesophase ratio of 20% or more. .