JP7304575B2 - Pitch manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing pitch.

The 21st century is said to be the era of carbon materials, and general-purpose carbon materials and high-performance carbon materials (e.g., carbon fiber and composite materials thereof, various electrode materials, heating elements, molded heat insulating materials, etc.) have been developed and commercialized.
According to Fuji Keizai Co., Ltd., demand for carbon fiber materials is expected to grow in the aircraft and automobile industries in the future, and the market for this field in Japan is expected to reach approximately 350 billion yen in 2030. there is
There are PAN-based and pitch-based carbon fiber raw materials. Other than carbon fiber, pitch-based materials are used as various raw materials for general-purpose carbon materials and high-performance carbon materials. Among them, graphite electrodes for electrical steelmaking, for which demand has been rapidly increasing recently, are manufactured only from pitch-based needle coke, which has excellent electrical conductivity and little elongation in the axial direction at high temperatures.
In addition, due to the recent increase in demand in China, the graphite electrode market soared to 1 million yen/t to 1.5 million yen/t at the end of 2018, and the high price continues today.

Pitch raw materials are roughly classified into petroleum residues and coal tar. The main suppliers are the petroleum refining industry, the steel industry, and the coke manufacturing industry. There are predictions that supply will dwindle and not be able to meet future demand.

In Japan, various pitches are usually produced starting from coal tar recovered from coke ovens. Coal tar is recovered in a yield of about 7% to 8% from the coke oven, which is a pyrolysis reaction.
For example, Non-Patent Document 1 discloses a method for producing pitch from existing coal tar. Patent Document 1 discloses a method for producing carbon fiber pitch from coal tar. Non-Patent Document 2 discloses a method of co-heating pitch and polyvinyl chloride in the presence of a solvent for the purpose of improving physical properties of coal-based mesophase pitch.

JP 2016-011422 A

Aromatics and tar industry handbook, 3rd edition, page 56 (edited by Japan Aromatics Industry Association) "Co-Heat Treatment of Mesophase Pitch and Polyvinyl Chloride-Modification in the Coexistence of Solvent-" TANSO 1991, Vol. 1991, No. 146, pp. 27-32

However, the coal used in the method described in Non-Patent Document 1 is limited to bituminous coal, which is mainly composed of strongly coking coal, and it is difficult to use lignite, which tends to cause a decrease in cold and hot coke strength. there is Neither the coal tar described in Patent Document 1 nor the coal-based mesophase pitch described in Non-Patent Document 2 is derived from lignite.
In Japan, it is said that there is no coal tar derived from lignite, which is the raw material, and pitch originating from coal tar derived from lignite. In addition, compared to coal tar derived from bituminous coal, lignite-derived coal tar is rich in aliphatics, has a low aromatic carbon ratio, has a small degree of condensation of aromatic rings, and has a high oxygen content. Transformation and, in particular, development to anisotropic carbon materials are considered extremely difficult.

In view of its properties, lignite exists in large quantities in the world, and although it is inexpensive, it is not fully utilized at present. It would be useful if such lignite could be used to produce pitch and be used as a general-purpose carbon material and a high-performance carbon material.
An object of the present invention is to provide a method for producing a pitch that can produce a practical pitch by using lignite synthetic oil derived from lignite or the solvent-insoluble matter of lignite synthetic oil.

According to one aspect of the present invention, a brown coal synthetic oil obtained by hydrothermally treating a mixture containing brown coal and water under pressure, or a solvent-insoluble portion of the brown coal synthetic oil, is used as a raw material, and the raw material is and heating under pressure to pitch the raw material; and separating the pitch from the reaction product obtained in the pitching step.

In the method for producing pitch according to one aspect of the present invention, the catalyst is preferably a halogen-containing compound.

In the pitch manufacturing method according to one aspect of the present invention, it is preferable that the halogen-containing compound is a halogen-containing organic compound, and the halogen-containing organic compound is polyvinyl chloride.

In the pitch manufacturing method according to one aspect of the present invention, it is preferable that the halogen-containing compound is a halogen-containing inorganic compound, and the halogen-containing inorganic compound is aluminum chloride.

In the method for producing pitch according to an aspect of the present invention, when the raw material is the brown coal synthetic oil, the mixing ratio of the catalyst and the brown coal synthetic oil (the catalyst/the brown coal synthetic oil) is a mass ratio of It is preferably 5/100 or more and 20/100 or less.

In the method for producing a pitch according to one aspect of the present invention, when the raw material is the solvent-insoluble matter, the mixing ratio of the catalyst and the solvent-insoluble matter (the catalyst/the solvent-insoluble matter) is a mass ratio of It is preferably 5/100 or more and 20/100 or less.

In the method for producing a pitch according to an aspect of the present invention, the step of pitching is performed under first conditions, and the first conditions are 0.2 MPa or more and 1.5 MPa or less, 260° C. or more and 450° C. or less, and preferably 20 minutes or more and 4 hours or less.

In the method for producing a pitch according to an aspect of the present invention, the step of pitching comprises: a first stage pitching step of pitching under the first condition; It is preferable to have a second stage pitching step in which pitching is performed under a second condition in which the length is long.

In the pitch manufacturing method according to an aspect of the present invention, the second conditions are preferably 0.2 MPa or more and 1.5 MPa or less, 250° C. or more and 350° C. or less, and 1 hour or more and 10 hours or less.

In the method for producing pitch according to an aspect of the present invention, the step of separating the pitch from the reaction product includes washing the reaction product, and then separating the washed reaction product by distillation under reduced pressure. is preferred.

The method for producing pitch according to an aspect of the present invention preferably further includes a step of carbonizing the pitch separated from the reaction product in the step of separating the pitch.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, it is possible to provide a pitch manufacturing method capable of manufacturing a practical pitch by using lignite synthetic oil derived from lignite or the solvent-insoluble matter of lignite synthetic oil.

4 is a flowchart showing the manufacturing method of the first embodiment; The figure which shows an example of a subcritical hydrothermal catalytic reaction process. The graph which shows the distillation curve of the lignite synthetic oil derived from A charcoal, B charcoal, and C charcoal. The graph which shows the fraction ratio of the lignite synthetic oil derived from A charcoal, B charcoal, and C charcoal. 6 is a flow chart showing a manufacturing method of the second embodiment; 6 is a flow chart showing a manufacturing method according to the third embodiment; Polarizing micrograph of the pitch of Example 1 (100x magnification). Polarizing micrograph of the pitch of Example 1 (400x magnification). Polarizing micrograph of the pitch of Example 2 (100x magnification). Polarizing micrograph of the pitch of Example 2 (400x magnification). Polarizing micrograph of the pitch of Example 3 (200x magnification). Polarizing micrograph of the pitch of Example 3 (500x magnification). Polarizing micrograph of the pitch of Example 3 (1000x magnification). Polarizing micrograph of the pitch of Example 4 (400x magnification). A polarizing microscope photograph of the pitch of Comparative Example 1 (400x magnification). 4 is a graph showing the relationship between the ratio of the number of naphthenic rings to the number of aromatic rings (Rn/Ra) and the aromatic index fa.

In the present specification, the numerical range represented using "to" means a range including the numerical value described before "to" as the lower limit and the numerical value described after "to" as the upper limit. do.

[First embodiment]
The method for producing pitch according to the present embodiment (hereinafter also referred to as "the production method of the present embodiment") is a method for producing pitch using synthetic brown coal oil or "solvent-insoluble matter of synthetic brown coal oil" as a raw material. .
In the present specification, lignite means coal having a total calorific value of 5,800 kcal/kg or more and less than 7,300 kcal/kg on an anhydrous and ashless basis. Bituminous coal means coal having a total calorific value of 8,100 kcal/kg or more and less than 8,400 kcal/kg on an anhydrous and ashless standard. Subbituminous coal means coal having a total calorific value of 7,300 kcal/kg or more and less than 8,100 kcal/kg on an anhydrous and ashless standard.
As used herein, the term “brown coal synthetic oil” refers to a synthetic oil derived from brown coal, specifically a synthetic oil obtained by subjecting a mixture containing brown coal and water to hydrothermal treatment under pressure. . This process of "hydrothermally treating a mixture containing lignite and water under pressure" is also called a subcritical hydrothermal catalytic reaction process. Details will be described later.
In the present specification, "solvent-insoluble matter of brown coal synthetic oil" means insoluble matter when the brown coal synthetic oil is dissolved in a solvent. For example, when brown coal synthetic oil is dissolved in hexane as a solvent, the hexane-insoluble matter is about 30% by mass with respect to the total amount of hexane. , corresponds to the “solvent-insoluble matter of brown coal synthetic oil” as a raw material.

FIG. 1 is a flow chart showing the manufacturing method of the first embodiment.
In the production method of the present embodiment, the raw material "brown coal synthetic oil" or "solvent-insoluble matter of brown coal synthetic oil" is heated under pressure in the presence of a catalyst, and step ST1 (hereinafter referred to as , also referred to as a “pitching step ST1”), and a step ST2 of separating pitch from the reaction product obtained in the pitching step ST1 (hereinafter also referred to as a “pitch separation step ST2”).

Conventionally, coal and coal tar have been used as raw materials for pitch. As described above, bituminous coal is mainly used as the raw material for coal tar, and lignite has been considered difficult to use because of its low aromatic carbon content and other properties.
As a raw material for pitch, the present inventors use synthetic oil derived from brown coal (brown coal synthetic oil) produced by a specific process (subcritical hydrothermal catalytic reaction process) or "solvent-insoluble matter of brown coal synthetic oil", It was found that a practical pitch can be produced by heating this raw material under pressure in the presence of a catalyst to form a pitch, and then separating the pitch from the reaction product (preferably by distillation under reduced pressure). rice field. Furthermore, the inventors have found that both isotropic pitch and mesophase pitch can be produced by selecting the catalyst used in pitching the raw material.
As used herein, the term “isotropic pitch” means that when a carbide obtained by carbonizing pitch (hereinafter also referred to as “pitch carbide”) is observed with a polarizing microscope, it usually has an optically isotropic structure. means a pitch that can only appear with
As used herein, "mesophase pitch" means pitch capable of forming an optically anisotropic structure when the pitch carbide is observed with a polarizing microscope. A method for observing pitch carbides with a polarizing microscope is described in the section of Examples.
According to the production method of the present embodiment, lignite-derived pitch can be produced by effectively utilizing unused lignite that exists in large quantities in the world.
Furthermore, according to the production method of the present embodiment, both isotropic pitch and mesophase pitch can be produced, so the produced pitch can be applied to general-purpose carbon materials and high-performance carbon materials depending on its structure. It is considered possible.
Such utilization of lignite is extremely useful from the viewpoint of noble use of unused resources and from the viewpoint of resolving future pitch raw material shortages.

First, the brown coal synthetic oil and the "solvent-insoluble matter of the brown coal synthetic oil", which are raw materials, will be described.

<Brown coal synthetic oil>
FIG. 2 is an overview of the subcritical hydrothermal catalytic reaction process (hereinafter also referred to as “Cat-HTR process”). FIG. 2 is an example of the Cat-HTR process.
In the Cat-HTR process shown in FIG. 2, first, a lignite water slurry, which is a mixture of lignite and water, is subjected to subcritical hydrothermal treatment at 240 atm and 350° C. in the presence of a catalyst, and the pressure is instantly increased to atmospheric pressure. Let it fall and separate the gas (approximately 15% by weight, mainly CO ₂ ). Water is separated from the resulting reactant slurry and further distilled at 450° C. to obtain about 60% by mass of modified coal and about 20% to 30% by mass of brown coal synthetic oil.
Normally, the yield of coal tar obtained from a coke oven is about 7% to 8% by mass, but the yield of brown coal synthetic oil obtained in this Cat-HTR process is about 20% to 30% by mass. % by mass and high. Therefore, according to the production method of the present embodiment, lignite can be used more efficiently than when pitch is produced from coal tar.
In the Cat-HTR process shown in FIG. 2, the pressure (240 atm), the temperature (350 ° C.) in the subcritical hydrothermal treatment, the pressure (atmospheric pressure) when the pressure is instantaneously lowered, and the distillation temperature (450 ° C. ) is not limited to this.

(Properties of brown coal synthetic oil)
The proportion of aromatic hydrocarbons contained in brown coal synthetic oil is usually 40% by mass to 60% by mass. The proportion of aliphatic hydrocarbons contained in brown coal synthetic oil is usually 40% to 60% by mass. The ratio (% by mass) of aromatic hydrocarbons and aliphatic hydrocarbons can be measured by a known ¹³ C-NMR method.
The elemental analysis values of brown coal synthetic oil are usually 82% to 84% by weight of carbon atoms, 8% to 10% by weight of hydrogen atoms, and 6% to 8% by weight of oxygen atoms. The elemental analysis value can be measured based on JIS M8813 (2004).
The boiling fraction of brown coal synthetic oil is usually 170°C to 620°C.

Table 1 shows the concentration of each element in brown coal synthetic oil produced by the Cat-HTR process using A coal (Indonesian brown coal), B coal (Indonesian brown coal) and C coal (Indonesian brown coal). .
Hereinafter, the synthetic lignite oil produced by the Cat-HTR process using coal A, coal B, and coal C will be referred to as "coal A-derived brown coal synthetic oil", "coal B-derived lignite synthetic oil", and "coal C-derived lignite synthetic oil". It is sometimes called lignite synthetic oil.
Table 2 shows the main specification values of IFO (Intermediate Fuel Oil) RMG380 (Residual Marine fuel oil kinematic viscosity 380 mm ² /s grade) and the physical property values of lignite synthetic oils derived from A coal, B coal and C coal. is.
FIG. 3 shows distillation curves of brown coal synthetic oils derived from coal A, coal B, and coal C.
FIG. 4 shows fraction ratios of brown coal synthetic oil derived from coal A, coal B, and coal C.

Description of Table 1 <1 indicates less than 1 ppm.
n/a indicates not analyzed.

- Description of Table 2 <1 indicates less than 1 ppm.
n/a indicates not analyzed.

The brown coal synthetic oil is not limited to the properties shown in Tables 1 and 2 and FIGS. 3 and 4 as long as it is obtained by a subcritical hydrothermal catalytic reaction process.

<Solvent-insoluble matter of brown coal synthetic oil>
As the solvent in the "solvent-insoluble matter of brown coal synthetic oil", it is preferable to obtain a solvent-insoluble matter of 30% by mass or more by dissolving the brown coal synthetic oil in such a solvent. Examples of the solvent include hexane, acetone, and benzene.

Each step of the manufacturing method of this embodiment will be described.

<Pitching process ST1>
The pitching step ST1 is a step of heating the raw material (brown coal synthetic oil or the solvent-insoluble portion of the brown coal synthetic oil) under pressure in the presence of a catalyst to form a pitch from the raw material.
Preferred ranges of the pressure, temperature, heating rate, reaction time, and stirring speed of the raw material in the pitching step ST1 are as follows from the viewpoint of favorably advancing the pitching of the raw material.

- Pressure The pressure in the pitching step ST1 is preferably 0.2 MPa or more and 1.5 MPa or less, more preferably 0.2 MPa or more and 1.0 MPa or less, and still more preferably 0.4 MPa or more and 0.8 MPa or less.

- Temperature The temperature in the pitching step ST1 is preferably 260°C or higher and 450°C or lower, more preferably 260°C or higher and 430°C or lower, and still more preferably 260°C or higher and 420°C or lower.

- Rate of temperature rise The rate of temperature rise is preferably 5°C/min or more and 20°C/min or less, more preferably 5°C/min or more and 10°C/min or less.

- Reaction time The reaction time in the pitching step ST1 is preferably 20 minutes or more and 4 hours or less, more preferably 20 minutes or more and 2 hours or less.

- Stirring speed of raw material It is preferable to perform the pitching step ST1 while stirring the raw material.
The stirring speed is preferably 300 rpm or more and 1200 rpm or less.

The pitching step ST1 is preferably performed under an inert gas atmosphere. Examples of inert gases include nitrogen, helium, and argon. The inert gas may be one type of gas or a mixed gas in which two or more types are mixed. Nitrogen is preferred as the inert gas.

The pitching step ST1 is preferably performed under the first condition from the viewpoint of making the pitching of the raw material more favorable. The first conditions are 0.2 MPa or more and 1.5 MPa or less, 260° C. or more and 450° C. or less, and 20 minutes or more and 4 hours or less.

(catalyst)
Preferably, the catalyst is a halogen-containing compound. Halogen-containing compounds are classified into halogen-containing organic compounds and halogen-containing inorganic compounds. Halogens in halogen-containing compounds include fluorine, chlorine, bromine, and iodine.
The halogen-containing organic compound and the halogen-containing inorganic compound will be described in order.

Halogen-containing organic compounds Halogen-containing organic compounds include, for example, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), chlorinated polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, chlorinated polystyrene, vinyl chloride-chlorinated vinylidene copolymers, vinyl chloride-ethylene chloride copolymers, vinyl chloride-propylene chloride copolymers, vinyl chloride-styrene copolymers, vinyl chloride-vinyl acetate copolymers, and the like.
The halogen-containing organic compound is preferably a chlorine-containing organic compound, and particularly preferably polyvinyl chloride (PVC), from the viewpoint of promoting the pitching of raw materials.
The polyvinyl chloride is not particularly limited, and may be a commercial product or one produced by a known method. The higher the purity of polyvinyl chloride, the more preferable it is, but it is not particularly limited as long as it functions as a catalyst.
The average degree of polymerization of polyvinyl chloride is preferably about 1000 or more and 1500 or less. That is, the average weight molecular weight of polyvinyl chloride is preferably about 7000 or more and about 10,000.

When the raw material is brown coal synthetic oil and the catalyst is a halogen-containing organic compound (preferably polyvinyl chloride), the mixing ratio of the catalyst and the brown coal synthetic oil (the catalyst/the brown coal synthetic oil) is the polycondensation of the brown coal synthetic oil. From the viewpoint of expressing the modification effect, the larger the better, but the mass ratio is preferably 5/100 or more and 20/100 or less, more preferably 5/100 or more and 10/100 or less, further preferably 8/100 or more and 10/100 or less. is.
When the ratio (the catalyst/the brown coal synthetic oil) is 5/100 or more by mass, the polycondensation reforming effect of the brown coal synthetic oil is likely to be exhibited.
When the ratio (the catalyst/the brown coal synthetic oil) is 20/100 or less by mass, the polycondensation reforming effect of the brown coal synthetic oil can be favorably exhibited and the cost can be reduced.

When the raw material is the "solvent-insoluble matter of brown coal synthetic oil" and the catalyst is a halogen-containing organic compound (preferably polyvinyl chloride), the mixing ratio of the catalyst and the "solvent-insoluble matter of brown coal synthetic oil" (said catalyst/said The solvent-insoluble content of brown coal synthetic oil) is preferably as large as possible from the viewpoint of expressing the polycondensation reforming effect of the solvent-insoluble content, but the mass ratio is preferably 5/100 or more and 20/100 or less, more preferably 5/100. 10/100 or less, more preferably 8/100 or more and 10/100 or less.
When the ratio (the catalyst/the solvent-insoluble matter of the brown coal synthetic oil) is 5/100 or more by mass, the polycondensation reforming effect of the solvent-insoluble matter is likely to be exhibited.
When the ratio (the catalyst/the solvent-insoluble matter of the brown coal synthetic oil) is 20/100 or less by mass, the polycondensation reforming effect of the solvent-insoluble matter can be satisfactorily expressed and the cost can be reduced. .

When a halogen-containing organic compound (preferably polyvinyl chloride) is used as a catalyst, the optical texture of the produced pitch carbide tends to become mosaic locally or entirely. The optical structure can be confirmed by observing the pitch carbide with a polarizing microscope.
The optical structure of the pitch carbide has a higher anisotropy in the order of mosaic structure, flow structure and domain structure. Table 3 shows an example of classification of optically anisotropic structures. The classification shown in Table 3 is based on Isao Mochida, Hidekazu Matsuoka, Keiko Maeda, et al., 16th Coal Science Conference/46th Joint Conference of Japan Fuel Association (1979), pp. 200-206.
Mosaic structures and flow structures are further classified according to size, as shown in Table 3. The anisotropy of the mosaic structure increases in the order of ultra-ultrafine mosaic, ultrafine mosaic, fine mosaic, medium-grain mosaic, coarse-grain mosaic, and ultra-coarse-grain mosaic. The flow structure becomes more anisotropic in the order of the coarse-grained flow structure and the flow structure.
Therefore, in the production method of the present embodiment, using a halogen-containing organic compound (preferably polyvinyl chloride) as a catalyst facilitates obtaining mesophase pitch. As a result, a pitch that can be applied to high-performance carbon materials can be produced.

Halogen-Containing Inorganic Compound Examples of halogen-containing inorganic compounds include aluminum chloride (AlCl ₃ ), aluminum bromide (AlBr ₃ ), titanium chloride (TiCl ₄ ), zirconium chloride (ZrCl ₄ ), and antimony fluoride (SbF ₅ ). , iron chloride (FeCl ₃ ), zinc chloride (ZnCl ₂ ), boron fluoride (BF ₃ ), boron chloride (BCl ₃ ), aluminum iodide (AlI ₃ ), gallium chloride (GaCl ₃ ), gallium bromide (GaBr ₃ ), antimony chloride (SbCl ₅ ), tin chloride (SnCl ₂ ), titanium bromide (TiBr ₄ ), zinc bromide (ZnBr ₂ ), tin bromide (SnBr ₂ ), iron bromide (FeBr ₃ ), fluorine aluminum oxide (AlF ₃ ), titanium fluoride (TiF ₄ ), zinc fluoride (ZnF ₂ ), tin fluoride (SnF ₂ ), and the like.
As the halogen-containing inorganic compound, a chlorine-containing inorganic compound is preferable from the viewpoint of promoting the pitching of the raw material, and aluminum chloride (AlCl ₃ ) is particularly preferable.
Aluminum chloride is not particularly limited, and may be obtained or produced by a known method. The purity of aluminum chloride is preferably as high as possible, but is not particularly limited as long as it functions as a catalyst.

When the raw material is brown coal synthetic oil and the catalyst is a halogen-containing inorganic compound (preferably aluminum chloride), the mixing ratio of the catalyst and brown coal synthetic oil (said catalyst/said brown coal synthetic oil) is the polycondensation reforming of brown coal synthetic oil. From the viewpoint of expressing the quality effect, the larger the better, but the mass ratio is preferably 5/100 or more and 20/100 or less, more preferably 10/100 or more and 20/100 or less, further preferably 10/100 or more and 15/100 or less. be.
When the ratio (the catalyst/the brown coal synthetic oil) is 5/100 or more by mass, the polycondensation reforming effect of the brown coal synthetic oil is likely to be exhibited.
When the ratio (the catalyst/the brown coal synthetic oil) is 20/100 or less by mass, the polycondensation reforming effect of the brown coal synthetic oil can be favorably exhibited and the cost can be reduced.

When the raw material is the "solvent-insoluble matter of brown coal synthetic oil" and the catalyst is a halogen-containing inorganic compound (preferably aluminum chloride), the mixing ratio of the catalyst and the "solvent-insoluble matter of brown coal synthetic oil" (said catalyst/said brown coal The solvent-insoluble content of the synthetic oil) is preferably as large as possible from the viewpoint of expressing the polycondensation reforming effect of the solvent-insoluble content, but the mass ratio is preferably 5/100 or more and 20/100 or less, more preferably 10/100 or more. It is 20/100 or less, more preferably 10/100 or more and 15/100 or less.
When the ratio (the catalyst/the solvent-insoluble matter of the brown coal synthetic oil) is 5/100 or more by mass, the polycondensation reforming effect of the solvent-insoluble matter is likely to be exhibited.
When the ratio (the catalyst/the solvent-insoluble matter of the brown coal synthetic oil) is 20/100 or less by mass, the polycondensation reforming effect of the solvent-insoluble matter can be satisfactorily expressed and the cost can be reduced. .

When a halogen-containing inorganic compound (preferably aluminum chloride) is used as a catalyst, the optical structure of pitch carbide produced tends to be isotropic.
Therefore, pitch produced using a halogen-containing inorganic compound (preferably aluminum chloride) as a catalyst is expected to be applied to general-purpose carbon materials.

<Pitch separation step ST2>
The pitch separation step ST2 is a step of separating pitch from the reaction product obtained in the pitch formation step ST1.
The method for separating the pitch is not particularly limited, but examples thereof include vacuum distillation, atmospheric distillation, solvent extraction, filtration, and centrifugation. Among them, the vacuum distillation method is preferable as the method for separating the pitch.

When the method for separating pitch is vacuum distillation, the pressure during vacuum distillation is preferably 4 Torr or more and 200 Torr or less, and the temperature is preferably 150° C. or more and 300° C. or less, from the viewpoint of facilitating pitch separation. Preferably, the heating time is 60 minutes or more and 180 minutes or less.

The pitch separation step ST2 preferably separates pitch from the reaction product obtained in the pitch formation step ST1 after washing the reaction product.
The reaction product is preferably washed with at least one of water washing and acid washing, and more preferably both water washing and acid washing.

Although the cleaning liquid used for acid cleaning is not particularly limited, it is preferably a mixed solution of an acid, an organic solvent and water. Acids include, for example, hydrochloric acid, sulfuric acid, and nitric acid. These may be used alone or in combination.
Examples of organic solvents include tetrahydrofuran (THF), aliphatic hydrocarbons (eg, pentane, hexane, etc.), aromatic hydrocarbons (eg, toluene, xylene, etc.), alcohols (eg, ethanol, etc.) and acetone. be done. These may be used alone or in combination. It is preferable to appropriately adjust the mixing ratio of the acid, the organic solvent and the water. The number of times of acid washing may be one or more.

Although the cleaning liquid used for water cleaning is not particularly limited, it is preferably a mixed solution of alcohol, an organic solvent (other than alcohol), and water.
Examples of the organic solvent include those listed in the section on acid cleaning. It is preferable to adjust the mixing ratio of alcohol, organic solvent and water as appropriate. The number of times of washing with water may be one or more.

That is, in the pitch separation step ST2, after washing the reaction product obtained in the pitching step ST1 (more preferably after performing both water washing and acid washing), the washed reaction product is distilled under reduced pressure. It is preferable to separate by

[Use of pitch]
The pitch produced by the production method of the present embodiment can be applied to, for example, general-purpose carbon materials and high-performance carbon materials.
In the production method of the present embodiment, both isotropic pitch and mesophase pitch can be produced.
Isotropic pitch can be suitably used as a general-purpose carbon material, taking advantage of the properties such as flexibility and slidability of the carbide.
Examples of general-purpose carbon materials include caking materials such as electrodes (for example, binders for steel), high-density isotropic carbon, isotropic carbon materials, graphite, and heat-resistant materials.
Mesophase pitch can be suitably used as a high-performance carbon material, taking advantage of the properties of its carbides, such as high elasticity and high conductivity.
Examples of high-performance carbon materials include carbon electrodes (eg, needle coke, etc.) and carbon fiber raw materials (eg, impregnating materials for electrodes, etc.).
The pitches produced in the second embodiment, the third embodiment, and other embodiments, which will be described later, can also be applied to the general-purpose carbon material and the high-performance carbon material.

[Second embodiment]
FIG. 5 is a flow chart showing the manufacturing method of the second embodiment.
The manufacturing method of the second embodiment differs from the first embodiment in that the pitching process is performed in two stages. That is, in the pitching process of the second embodiment, the pitching process ST1 of the first embodiment is followed by the second pitching process. Since other points are the same as those of the first embodiment, description thereof will be omitted or simplified.
As shown in FIG. 5, the manufacturing method of the second embodiment includes a first stage pitching step ST11 for pitching the raw material brown coal synthetic oil or "solvent-insoluble matter of brown coal synthetic oil" under predetermined conditions; It has a second pitching step ST12 of further pitching the raw material under predetermined conditions, and a step of separating pitch from the reaction product obtained in the second pitching step (pitch separation step ST2).

<First stage pitching step ST11>
The first stage pitching step ST11 is synonymous with the pitching step ST1 of the first embodiment, and the preferred range is also the same. That is, the conditions of the first-stage pitching step ST11 are preferably in the same range as the pressure, temperature, heating rate, reaction time, and raw material stirring speed in the pitching step ST1 in the first embodiment. It is more preferable to carry out under the first condition in one embodiment.

<Second-stage pitching step ST12>
Preferred ranges of the pressure, temperature, temperature increase rate, reaction time, and raw material stirring speed in the second-stage pitching step ST12 are as follows from the viewpoint of making the raw material pitch more favorable.

- Pressure The pressure in the second-stage pitching step ST12 is preferably 0.2 MPa or more and 1.5 MPa or less, more preferably 0.2 MPa or more and 1.0 MPa or less, and still more preferably 0.4 MPa or more and 0.8 MPa or less.

- Temperature The temperature in the second-stage pitching step ST12 is preferably lower than the first condition (260°C or higher and 450°C or lower) in the first embodiment.
Specifically, the temperature in the second pitching step ST12 is preferably 250° C. or higher and 350° C. or lower, more preferably 250° C. or higher and 320° C. or lower, and still more preferably 250° C. or higher and 300° C. or lower.

- Rate of temperature rise The rate of temperature rise to reach the above temperature is preferably 5°C/min or more and 20°C/min or less, more preferably 5°C/min or more and 15°C/min or less.

- Reaction time The reaction time in the second-stage pitching step ST12 is preferably longer than the first condition (20 minutes or more and 4 hours or less) in the first embodiment.
Specifically, the reaction time in the second-stage pitching step ST12 is preferably 30 minutes or more and 10 hours or less, more preferably 30 minutes or more and 5 hours or less.

- Stirring speed of raw material It is preferable to perform the second-stage pitching step ST12 while stirring the raw material.
The stirring speed is preferably 300 rpm or more and 1200 rpm or less.

The second-stage pitching step ST12 is preferably performed in an inert gas atmosphere as in the pitching step ST1 of the first embodiment.

The second stage pitching step ST12 is preferably performed under the second condition from the viewpoint of making the pitching of the raw material more favorable. The second conditions are 0.2 MPa or more and 1.5 MPa or less, 250° C. or more and 350° C. or less, and 1 hour or more and 10 hours or less.

That is, in the pitching step in the second embodiment, the first stage pitch is pitched under the first conditions (0.2 MPa or more and 1.5 MPa or less, 260° C. or more and 450° C. or less, and 20 minutes or more and 4 hours or less). Pitching step ST11 and second conditions (0.2 MPa or more and 1.5 MPa or less, 250 ° C. or more and 350 ° C. or less, and 30 minutes or more and 10 hours or less) with a lower temperature and a longer time than the first conditions. It is preferable to have a second-stage pitching step ST12 in which

[Effect of Second Embodiment]
When pitch is produced by the production method of the second embodiment (the method of performing the pitching process in two steps), any of the pitch yield, the pitch carbide yield (pitch basis), and the pitch carbide yield (raw material basis) can also be increased.
Moreover, when the pitch is produced by the production method of the second embodiment, the aromatic ring number Ra of the pitch can be increased. In particular, the pitch produced by adding polyvinyl chloride, which is a halogen-containing organic compound, as a catalyst has an aromatic index fa (BL method), an aromatic index fa ( ¹³ C-NMR method), an aromatic ring number Ra, and Both the number of naphthene rings Rn are increased, while the ratio of the number of naphthene rings to the number of aromatic rings (Rn/Ra) can be decreased, so that approximately fa>0.6 (BL method) and Rn/Ra<0 There tends to be a harmonious ratio where the mesophase pitch appears to be 0.8.
Therefore, according to the production method of the second embodiment, more practical pitch and pitch carbide can be produced.

[Third Embodiment]
FIG. 6 is a flow chart showing the manufacturing method of the third embodiment.
The manufacturing method of the third embodiment differs from the second embodiment in that it includes a step of further carbonizing the pitch separated in the pitch separation step ST2 (hereinafter also referred to as "carbonization step ST3"). different from Since other points are the same as those of the second embodiment, description thereof will be omitted or simplified.
Specifically, the manufacturing method of the third embodiment includes a first pitching step ST11, a second pitching step ST12, a pitch separation step ST2, and a carbonization step ST3.

<Carbonization process>
The carbonization step ST3 is a step of further carbonizing the pitch separated in the pitch separation step ST2.
A carbonization method is not particularly limited. As a carbonization method, for example, there is a method of heating pitch in an inert gas atmosphere. Examples of the inert gas include the same inert gases as listed in the section of the pitching step ST1 in the first embodiment.

From the viewpoint of good progress of carbonization, the carbonization temperature in the carbonization step ST3 is preferably 450° C. or higher and 650° C. or lower, the heating rate is preferably 1° C./min or higher and 5° C./min or lower, and the holding time is is preferably 30 minutes or more and 4 hours or less.
The carbonization device is not particularly limited as long as it can carbonize the pitch in a low-oxygen atmosphere (preferably in an inert gas atmosphere), and a known carbonization device can be used.

[Effect of the third embodiment]
According to the third embodiment, by selecting the catalyst used when pitching the raw material, pitch carbide having an optically isotropic structure, pitch carbide having an optically anisotropic structure, or optically isotropic Pitch carbides can be produced that have both anisotropic and optically anisotropic textures. Therefore, the manufactured pitch carbide can be applied to applications that make use of the respective advantages of isotropic pitch or mesophase pitch. Applications include, for example, the applications described in the "Pitch Applications" section of the first embodiment.

[Other embodiments]
The present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope of achieving the object of the present invention are included in the present invention.
For example, in the first embodiment, a carbonization step may be performed after the pitch separation step.
For example, in the second and third embodiments, the pitching process may be performed in three stages or more.

Examples of the present invention will be described below. The present invention is by no means limited by these examples.

[Example 1]
As a raw material, lignite synthetic oil produced by the subcritical hydrothermal catalytic reaction process shown in FIG. 2 was used. This brown coal synthetic oil is a coal A-derived brown coal synthetic oil having properties shown in Tables 1 and 2 and FIGS.
As a catalyst, polyvinyl chloride (manufactured by Nacalai Tesque, product number: 36305-65, average degree of polymerization: 1020) was used.

<Pitching process (first stage pitching process)>
8 parts by mass of PVC was added to 100 parts by mass of brown coal synthetic oil. The total amount of brown coal synthetic oil and PVC is 50 g.
A mixture of brown coal synthetic oil and PVC was put into the autoclave, and after the inside of the autoclave was replaced with the reaction atmosphere gas ( _N gas) five times, the inside of the system was maintained at room temperature (25°C) at an initial pressure of 0.4 MPa. .
Next, while maintaining the initial pressure, the mixture was heated to 390°C at a heating rate of 10°C/min using a band heater, and heated at 390°C for 1 hour while stirring at 1000 rpm (first condition), the brown coal synthetic oil was pitched.
Next, the band heater was removed, the reaction product was quenched by air cooling, the inside of the system was returned to room temperature (25° C.), and the gas was removed.

The reaction products were then directly collected and quantified. In addition, using tetrahydrofuran (THF), deposits on the stirrer or the like were also collected and quantified.

<Pitch separation process>
(Acid cleaning)
Using a mixed solution of water and THF (water: THF = 1:1 (mass ratio)), the entire amount of the reaction product (including deposits on the stirrer etc.) is collected in an eggplant flask, and then acid washing is performed. gone.
Specifically, a mixed solution A of hydrochloric acid/water/THF having a concentration of 35% by mass (mass ratio is hydrochloric acid:water:THF=1:1:2 to 1:1:3) is prepared, and reaction product 1 10 parts by mass of the mixed solution A was mixed with respect to parts by mass, ultrasonically shaken, and distilled by an evaporator to remove THF. Thereafter, the aqueous solution was removed, and washing with boiling water was performed three times. This washing with boiling water three times was defined as one set, and this was repeated two sets.

(water wash)
Next, the reaction product after acid washing was washed with water. Specifically, a mixed solution B of ethanol/water/THF (mass ratio: ethanol:water:THF=1:1:1) was prepared, and mixed solution B was added to 1 part by mass of the reaction product after acid washing. 10 parts by mass of were mixed, and after ultrasonic shaking, distillation was performed using an evaporator to remove THF. After that, washing with boiling ethanol aqueous solution was performed five times.

(Equalizing treatment)
After drying the reaction product after washing with water, the reaction product was dissolved in THF.

(Reduced pressure distillation)
Next, vacuum distillation was performed for 2 hours at a pressure of 8 Torr and a temperature of 220° C. (heating time: 120 minutes) to distill the pitch. As described above, the lignite-derived pitch of Example 1 was obtained.

<Carbonization process>
A 3 g sample was taken from the distilled pitch and carbonized under the following conditions.
As described above, pitch carbide was further obtained from the pitch of Example 1.
-conditions-
・Equipment: Carbonization equipment (manufactured by KRI, carbonization equipment equipped with an electric heating horizontal carbonization furnace)
・Temperature increase rate: 1.5°C/min ・Carbonization temperature: 600°C
・Retention time: 1 hour ・Atmospheric gas: Nitrogen (300 mL/min)

[Example 2]
Pitch and pitch carbide of Example 2 were obtained in the same manner as in Example 1, except that after the first pitching step, the second pitching step was performed by the following method.

<Second-stage pitching process>
In the first-stage pitching step, the inside of the system was returned to room temperature (25° C.), degassed, and then the inside of the system was brought to 0.4 MPa. The reaction product obtained in the first stage pitching step was reheated to 280°C at a heating rate of 10°C/min and heated at 280°C for 4 hours while being stirred at 1000 rpm (second condition), The reaction product was further pitted.

[Example 3]
Pitch and pitch carbide of Example 3 were obtained in the same manner as in Example 2, except that this "solvent-insoluble matter of brown coal synthetic oil" was used as a raw material instead of brown coal synthetic oil in Example 2. . The "solvent-insoluble matter of brown coal synthetic oil" was prepared as follows.

<Solvent-insoluble matter of brown coal synthetic oil>
2.5 g of brown coal synthetic oil and 50 mL of hexane were mixed, and the resulting mixture was placed in a Soxhlet extractor and heated at 50° C. while refluxing hexane about 50 times to extract hexane-soluble matter. After that, the hexane-insoluble matter was fractionated using a thimble. Specifically, the residue remaining in the thimble was dried at 100° C. and hexane was distilled. The residue after this hexane distillation was used as a hexane-insoluble matter (solvent-insoluble matter of brown coal synthetic oil).

[Examples 4 to 6]
For Example 1, instead of 8.0 parts by mass of PVC, 13.33 parts by mass of aluminum chloride (manufactured by Nacalai Tesque, product number: 01711-15, purity: 98%) was used, and the first stage pitching process Pitch and pitch carbides of Examples 4 to 6 were obtained in the same manner as in Example 1, except that the temperature and time of 1 were changed to those shown in Table 4.

[Example 7]
Compared to Example 2, 13.33 parts by mass of aluminum chloride (AlCl ₃ ) was used instead of 8.0 parts by mass of PVC, and the temperature and time of the first stage pitching process were changed to the temperatures and times shown in Table 4. Pitch and pitch carbide of Example 7 were obtained in the same manner as in Example 2, except that the temperature in the second stage pitching step was changed to the temperature shown in Table 4.

[Comparative Example 1]
Pitch and pitch carbide of Comparative Example 1 were obtained in the same manner as in Example 2, except that no catalyst was added.

〔evaluation〕
<Pitch yield and pitch carbide yield>
Pitch yield (Y _p ), pitch carbide yield (pitch basis) (Y ₁ ) and pitch carbide yield (raw material basis) (Y ₂ ) were calculated by the following methods.
All yields were calculated excluding ash. That is, pitch yield (Y _p ), pitch char yield (based on pitch) (Y ₁ ) and pitch char yield (based on feedstock) (Y ₂ ) are yields on an ashless basis. Table 4 shows the results.

[Measurement of ash content]
The ash content contained in the raw material, pitch and pitch carbide was measured under the following conditions. The dry mass-based ash content was calculated by the following formula (10).
Dry mass-based ash content [wt%] = W _ash / W _dry × 100 (10)
W _dry : 120°C dry mass [g]
W _ash : Combustion ash mass [g]
-conditions-
・ Apparatus: Differential thermal balance TG-DTA (manufactured by Mac Science)
・Atmosphere: Air atmosphere, 200 mL/min
・Temperature condition of 120°C dry mass W _dry Heating rate: 10°C/min, temperature rise from room temperature (25°C) to 120°C Holding time: 120°C, 20 min
・Temperature conditions for combustion ash mass W _ash Heating rate: 10°C/min from 120°C to 950°C

[Pitch yield (Y _p )]
The pitch yield (Y _p ) was calculated by Equation (1).
Y _P (wt%) = {W ₂ * (100-A _P )/100}/{W ₁ * (100-A ₀ )/100} (1)
W ₁ : Input amount of raw material (g)
W ₂ : Yield of pitch (g)
A ₀ : ash content of raw material (wt%)
A _P : Ash content of pitch (wt%)

[Pitch carbide yield (pitch basis) (Y ₁ )]
The pitch carbide yield (Y ₁ ) was calculated by Equation (2).
Y ₁ (wt%)={Wc*(100−A _C )/100}/{W _P *(100−A _P )/100} (2)
W _P : Mass of pitch before carbonization (g)
W _C : Mass of pitch carbide (g)
A _P : Ash content of pitch (wt%)
_AC : Ash content of pitch carbide (wt%)

[Pitch carbide yield (raw material basis) (Y ₂ )]
The pitch carbide yield (Y ₂ ) was calculated by the formula (3) from the results of the formulas (1) and (2).
_Y2 (wt%) = _YP x _Y1 /100 (3)
Y _P : Pitch yield (wt%) calculated by the above formula (1)
Y ₁ : Pitch carbide yield (pitch basis) calculated by the above formula (2) (wt%)

-Explanation of Table 4 The numbers in parentheses in Example 3 indicate the yield based on the mass of the "solvent-insoluble matter of brown coal synthetic oil".

As shown in Table 4, the pitches and pitch carbides of Examples 1 to 7 produced by adding a catalyst (PVC or AlCl ₃ ) to brown coal synthetic oil or "solvent-insoluble matter of brown coal synthetic oil" Pitch yield (Y _p ), pitch carbide yield (based on pitch) (Y ₁ ), and pitch carbide yield (based on raw material) (Y ₂ ) are higher than the pitch and pitch carbide of Comparative Example 1 produced without Both tended to increase.
In Comparative Example 1, although the pitch yield (Y _p ) was high, both the pitch carbide yield (based on pitch) (Y ₁ ) and the pitch carbide yield (based on raw material) (Y ₂ ) were low. In Comparative Example 1, it is considered that the polycondensation reforming of the brown coal synthetic oil was insufficient because no catalyst was added. It is believed that the pitch and pitch carbides of Comparative Example 1 have no practical utility.
According to the pitches and pitch carbides of Examples 1 to 7, the polycondensation reforming effect due to the addition of the catalyst was confirmed.
Further, by comparing Example 2 and Example 1, and comparing Example 7 and Example 6, it was found that the pitch yield (Y _p ) and the pitch carbide yield ( It has been found that both the pitch basis) (Y ₁ ) and the pitch carbide yield (raw basis) (Y ₂ ) can be increased.

<Structural analysis of pitch>
The aromatic index fa, the number of aromatic rings (Ra), the number of naphthenic rings (Rn), and the ratio of the number of naphthenic rings to the number of aromatic rings (Rn/Ra) of the pitch were calculated by the following methods.
The aromaticity index fa of the pitch was calculated by two methods, a method of directly determining by ¹³ C-NMR and a method of analyzing from ¹ H-NMR data by the Brown-Radner method (hereinafter also referred to as “BL method”). . Table 5 shows the results.

(Aromatic index fa ( ¹³ C-NMR method))
The aromatic index fa ( ¹³ C-NMR method) is attributed to the chemical shift of aromatic carbon by ¹³ C-NMR (manufactured by JEOL Ltd., ECX-400) after completely dissolving 0.1 g of pitch in hot quinoline. The integral value of the peak attributed to the aliphatic chemical shift was obtained, and the calculation was performed based on these integral values.

(Aromatic index fa (BL method), number of aromatic rings Ra, number of naphthenic rings Rn, and ratio Rn/Ra)
The aromatic index fa (BL method) was measured by ¹ H-NMR (manufactured by Bruker Japan Co., Ltd. (product number: DRX500) using a soluble matter of 0.1 g of pitch in a mixed solvent (1:1) of THF and pyridine. Aromatic hydrogen (Ha) and aliphatic hydrogens (Hα, Hβ and Hγ) at α-, β- and γ-positions were calculated from the chemical shift peaks obtained by the BL method.
The number of rings in the average structure in Table 5 calculates the aromatic hydrogen (Ha) and the aliphatic hydrogen (Hα, Hβ and Hγ) in the same manner as the aromatic index fa (BL method), Furthermore, molecular weight distribution data based on elemental analysis values (JIS M8813 (2004)) and gel permeation chromatography (GPC) (manufactured by Tosoh Corporation, HLC-8220 type)) were added and calculated by the BL method. Table 5 shows the number of aromatic rings (Ra), the number of naphthenic rings (Rn), and the ratio of the number of naphthenic rings to the number of aromatic rings (Rn/Ra).

(Relationship between the ratio of the number of naphthenic rings to the number of aromatic rings (Rn/Ra) and the aromatic index fa)
FIG. 12 is a graph showing the relationship between the ratio of the number of naphthenic rings to the number of aromatic rings (Rn/Ra) and the aromatic index fa. Also shown in FIG. 12 are plots of the following three petroleum-based pitches 1-3, and the peri-type fa maximum value curve (theoretical value vs. Rn/Ra). In FIG. 12, the aromatic index fa of petroleum pitches 1 to 3 is the value analyzed by the BL method.
・Petroleum pitch 1 (A240 in FIG. 12): 240° C. distillation residue manufactured by Ashland Co., USA ・Petroleum pitch 2 (Y pitch in FIG. 12): Pitch obtained by domestic coking process ・Petroleum pitch 3 (Hydrogenated pitch Y in FIG. 12) ... Pitch obtained by hydrogenating petroleum-based pitch 2

-Description of Table 5-
">7.0 (estimated)" indicates that the number of aromatic rings Ra is estimated to exceed 7.0.
"-" indicates not calculated.

From Table 5 and FIG. 12, the pitches of Examples 1 to 7 showed higher aromatic index fa calculated from ¹³ C-NMR than the pitch of Comparative Example 1.
Among them, the pitches of Examples 1 to 3 and Examples 6 to 7 had an aromatic index fa of 0.73 or more calculated by the ¹³ C-NMR method.
As shown in FIG. 12, when the pitches of Examples 1 to 3 and Examples 6 to 7 and petroleum-based pitches 1 to 3 are compared using the aromatic index fa obtained by the BL method, Example 2 The pitch (P2-P in FIG. 12) was close to petroleum-based pitches 2 to 3 (Y pitch and hydrogenated Y pitch in FIG. 12).

<Optical structure of pitch carbide>
The pitch carbide was observed by the following method using a polarizing microscope (manufactured by Leica Microsystems, DM2700P).
A 0.5 g sample was taken from the pitch carbide obtained in each example. This sample was covered with resin and the resin was polished to prepare a sample for microscopic observation.
A polarizing microscope was set to a crossed Nicols state, and a quartz test plate was inserted to observe the sample for microscopic observation.

7A-7B are polarizing micrographs of the pitch carbides of Example 1 (100× and 400× magnification). The pitch carbide of Example 1, which was produced by adding PVC as a catalyst to lignite synthetic oil, had a mixture of an isotropic structure and an anisotropic structure having a mosaic structure. In the pitch carbides of Example 1, the isotropic structure was slightly larger than the anisotropic structure.
8A-8B are polarizing micrographs of the pitch carbides of Example 2 (100× and 400× magnification). The pitch carbide of Example 2, which was produced by adding PVC as a catalyst to lignite synthetic oil, had a medium-grain mosaic structure on the entire surface and an anisotropic structure.
Figures 9A-9C are polarizing micrographs of the pitch carbides of Example 3 (at 200x, 500x and 1000x magnification). The pitch carbide of Example 3, which was produced by adding PVC as a catalyst to the "solvent-insoluble matter of brown coal synthetic oil", had an anisotropic texture of fine and medium-grain mosaics on almost the entire surface.

FIG. 10 is a polarizing micrograph of the pitch carbide of Example 4 (400× magnification). The pitch carbide of Example 4, which was produced by adding _AlCl3 as a catalyst to lignite synthetic oil, had an isotropic structure over the entire surface.
The pitch carbides of Examples 5 to 7, which were produced by adding AlCl ₃ as a catalyst to brown coal synthetic oil, were also observed with a polarizing microscope. As a result, the pitch carbides of Examples 5 to 7 all had an isotropic structure.

FIG. 11 is a polarizing microscope photograph of pitch carbide of Comparative Example 1 (magnification: 400).
The pitch carbide of Comparative Example 1, which was produced without adding a catalyst to the brown coal synthetic oil, had an isotropic structure.

In the production method of the present invention, pitch can be produced using lignite synthetic oil derived from lignite or "solvent-insoluble matter of lignite synthetic oil", so lignite that exists in large quantities in the world and is often unused can be effectively used. Since the produced pitch can be applied to both general-purpose carbon materials and high-performance carbon materials, the production method of the present invention has industrial applicability.

ST1... Pitching process, ST11... First stage pitching process, ST12... Second stage pitching process, ST2... Pitch separation process, ST3... Carbonization process.

Claims (10)

Synthetic lignite oil obtained by hydrothermally treating a mixture containing lignite and water under pressure, or a solvent-insoluble portion of the synthetic lignite oil as a raw material,
Heating the raw material under pressure in the presence of a catalyst to pitch the raw material;
a step of separating pitch from the reaction product obtained in the pitching step;
has
The catalyst is a halogen-containing organic compound or a halogen-containing inorganic compound,
The halogen-containing organic compound is polyvinyl chloride, polyvinylidene chloride, chlorinated polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, chlorinated polystyrene, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-ethylene chloride copolymer. , a vinyl chloride-propylene chloride copolymer, a vinyl chloride-styrene copolymer, or a vinyl chloride-vinyl acetate copolymer,
The halogen-containing inorganic compound includes aluminum chloride, aluminum bromide, titanium chloride, zirconium chloride, antimony fluoride, iron chloride, zinc chloride, boron fluoride, boron chloride, aluminum iodide, gallium chloride, gallium bromide, and antimony chloride. , tin chloride, titanium bromide, zinc bromide, tin bromide, iron bromide, aluminum fluoride, titanium fluoride, zinc fluoride, or tin fluoride. In the pitch manufacturing method according to claim 1 ,
The method for producing pitch, wherein the halogen-containing organic compound is polyvinyl chloride. In the pitch manufacturing method according to claim 1 ,
The method for producing pitch, wherein the halogen-containing inorganic compound is aluminum chloride. In the pitch manufacturing method according to any one of claims 1 to 3 ,
When the raw material is the lignite synthetic oil, the mixing ratio of the catalyst and the lignite synthetic oil (the catalyst/the lignite synthetic oil) is 5/100 or more and 20/100 or less in terms of mass ratio. Production method. In the pitch manufacturing method according to any one of claims 1 to 3 ,
When the raw material is the solvent-insoluble matter, the mixing ratio of the catalyst and the solvent-insoluble matter (the catalyst/the solvent-insoluble matter) is 5/100 or more and 20/100 or less by mass. Production method. In the pitch manufacturing method according to any one of claims 1 to 5 ,
The step of pitching is performed under a first condition,
The pitch manufacturing method, wherein the first conditions are 0.2 MPa or more and 1.5 MPa or less, 260° C. or more and 450° C. or less, and 20 minutes or more and 4 hours or less. In the pitch manufacturing method according to claim 6 ,
The step of pitching includes a first pitching step of pitching under the first condition, and a two-stage pitching step of pitching under a second condition of lower temperature and longer time than the first condition. A method for producing pitch, comprising a step of forming a pitch. In the pitch manufacturing method according to claim 7 ,
The second condition is 0.2 MPa or more and 1.5 MPa or less, 250° C. or more and 350° C. or less, and 1 hour or more and 10 hours or less. In the pitch manufacturing method according to any one of claims 1 to 8 ,
The step of separating the pitch from the reaction product comprises washing the reaction product and then separating the washed reaction product by distillation under reduced pressure. In the pitch manufacturing method according to any one of claims 1 to 9 ,
A method for producing pitch, comprising a step of further carbonizing the pitch separated from the reaction product in the step of separating the pitch.

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