JP6712011B2 - High softening point pitch manufacturing method - Google Patents

Description

The present invention relates to a method for producing a high softening point pitch using ethylene bottom oil as a raw material.

Carbon fibers are conventionally manufactured mainly by two methods. In the first method, PAN-based carbon fibers are manufactured by subjecting polyacrylonitrile (PAN) to flame-proofing treatment and carbonization treatment. In the second method, pitch-based carbon fibers are produced by melt-spinning a high softening point pitch obtained by heat treatment of heavy oil, and then subjecting it to infusibilization treatment, carbonization treatment and the like.

Coal tar produced from coal and petroleum heavy oil produced by fractional distillation of crude oil are often used as the raw material of pitch necessary for producing pitch-based carbon fiber, but hydrocarbons such as naphtha are used. It is also possible to use ethylene bottom oil, which is a heavy oil obtained in the process of thermally decomposing ethylene to produce ethylene and the like.

Pitch obtained from ethylene bottom heavy oil as a raw material has the similar aromaticity to coal tar, etc., less impurities such as solvent-insoluble metal oxides, and stable quality. Is mentioned. Furthermore, when ethylene bottom oil is used as a raw material, it produces an optically isotropic pitch with a high softening point that has a high oxidation reactivity, which is an infusibilizing treatment during carbon fiber preparation, and contains a relatively large amount of aliphatic hydrocarbon components. When this high softening point pitch is used as a raw material to produce carbon fibers, carbon fibers having high strength and high elongation can be obtained. However, ethylene bottom oil has a drawback that the yield of pitch is low because the average molecular weight of the heavy oil component is lower than that of other heavy oils.

In order to improve the yield of pitch produced from ethylene bottom oil as a raw material, a method has been proposed in which ethylene bottom oil is crosslinked and heavy by treating with nitric acid or an oxidizing gas to improve the pitch yield ( Japanese Patent No. 4349627; Patent Document 1). However, this method requires a dedicated facility for crosslinking/heaviening, which is not economically disadvantageous, and also causes the problem that oxygen atoms and nitrogen atoms are incorporated into the pitch during heavy/crosslinking. There is.

Further, as a method for producing a pitch in which an aromatic compound is crosslinked to improve the molecular weight, a method using hydrogen fluoride/boron trifluoride as a catalyst (Japanese Patent No. 2917486; Patent Document 2), chlorine, thionyl chloride, A method for reacting a halogen-containing additive such as sulfuryl chloride, bromine, thionyl bromide, iodo, and phosphoryl chloride (Patent No. 3015949; Patent Document 3) is known, and by applying these to ethylene bottom oil, Improvement of pitch yield is expected. However, these methods require difficult-to-handle acids and halogen-containing additives, and these acids and additives remain in the carbon fiber and adversely affect the physical properties.

Japanese Patent No. 4349627 Japanese Patent No. 2917486 Japanese Patent No. 3015949

In view of the above-mentioned conventional techniques, it is an object of the present invention to provide a production method capable of obtaining a high softening point pitch with a high yield by a simple operation using ethylene bottom oil as a main raw material.

By mixing dicyclopentadiene with ethylene bottom oil or ethylene bottom oil heavy component, the inventors of the present invention crosslink the dicyclopentadiene to promote polycondensation of heavy oil constituent molecules during heat treatment. The present invention has been completed by finding that it acts as an agent, the average molecular weight of the raw material heavy oil component is improved, and the yield of high softening point pitch obtained by reducing volatile components by distillation is improved.

That is, the present invention relates to a method for manufacturing the pitches [1] to [6] below.
[1] A step of preparing an ethylene bottom stock oil containing 10 mass% or more of ethylene bottom oil heavy component and 1 to 30 mass% of dicyclopentadiene, a step of heat treating the stock oil (step 2) ), and a step (step 3) of distilling the heat-treated product to obtain pitch as a high boiling point component.
[2] The method for producing a pitch according to item 1 above, wherein an ethylene bottom stock oil containing 50 mass% or more of an ethylene bottom oil heavy component is used.
[3] The method for producing a pitch according to the above item 1 or 2, which further uses a feedstock oil containing a heavy oil selected from coal tar and a petroleum heavy oil.
[4] The method for producing the pitch according to any one of the preceding items 1 to 3, wherein the heat treatment temperature is 300 to 450° C. [5] The production of the pitch according to any of the items 1 to 4, wherein the heat treatment pressure is 0 to 2 MPaG. Method [6] The method for producing a pitch according to any one of items 1 to 5, wherein at least a part of the dicyclopentadiene is derived from decomposed kerosene.

According to the present invention, a high softening point pitch can be obtained in a high yield by a simple method from an ethylene bottom base stock oil containing ethylene bottom oil or ethylene bottom oil heavy component as a main component and containing dicyclopentadiene. You can In particular, when cracked kerosene is used as a source of dicyclopentadiene, both ethylene bottom oil and cracked kerosene are products obtained by a general petrochemical industrial process, so that it is very easy to secure raw materials.

It is a flow figure showing a petrochemical process which thermally decomposes naphtha etc., and a manufacturing process of ethylene bottom oil and cracked kerosene.

Hereinafter, embodiments of the present invention will be described in detail.
The pitch manufacturing method of the present invention includes the following steps 1 to 3 in this order.
Step 1: a feedstock oil preparation step of mixing an ethylene bottom oil heavy component and dicyclopentadiene to prepare an ethylene bottom feedstock oil,
Step 2: a heat treatment step of heating the feedstock oil obtained in Step 1,
Step 3: A distillation step in which the heat-treated product obtained in Step 2 is distilled to recover pitch as a high boiling point component.

Further, before and after each step, another step may be included without departing from the spirit of the present invention. For example, a step of removing the solid matter by centrifugation may be appropriately added.
In the petrochemical industry, in general, raw materials containing at least one kind of petroleum such as naphtha, kerosene, gas oil, and natural gas liquid are pyrolyzed at high temperature, and the resulting pyrolyzate is distilled to obtain ethylene and propylene. Separated into other distillates such as other olefins, aromatic compounds such as benzene, toluene and xylene, cracked kerosene, cracked gasoline, etc. to make products. Of these fractions, the heavy fraction having the highest boiling point is called ethylene bottom oil.

The general process of the petrochemical industry and the extraction process of ethylene bottom oil are as shown in FIG. Ethylene bottom oil is a product that is separated and produced in the pre-distillation system, which is a process immediately after the pyrolysis furnace. The steps from pyrolysis to separation of ethylene bottom oil are carried out while maintaining a high temperature of 300°C or higher. In this temperature range, the dicyclopentadiene described below is dissociated into cyclopentadiene and the like by the reverse Diels-Alder reaction and removed from the ethylene bottom oil by distillation. Therefore, the ethylene bottom oil contains almost no dicyclopentadiene.

The properties of ethylene bottom oil depend on the type of naphtha-containing raw material, thermal cracking conditions, operating conditions of the refining distillation column, etc., but as a general property, the content ratio of aromatic hydrocarbons is 50% by mass or more, flammability The point is 70 to 90°C.

The heavy ethylene bottom oil component used in the ethylene bottom stock oil of the present invention is obtained by distilling off a low boiling point component from ethylene bottom oil by distillation. In this case, the initial boiling point of the ethylene bottom oil heavy component is preferably 300°C or lower, more preferably 270°C or lower, and further preferably 250°C or lower. When the initial boiling point exceeds 300°C, the viscosity of the ethylene bottom oil heavy component and the ethylene bottom feedstock oil becomes high, and mixing with dicyclopentadiene becomes difficult.

The ratio of the ethylene bottom oil heavy component in the ethylene bottom stock oil in the present invention is 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass. % Or more. If it is less than 10% by mass, the effect of improving the yield according to the present invention cannot be sufficiently obtained. Since the ethylene bottom oil usually contains 50% by mass or more of the bottom component (ethylene bottom oil heavy component) when the initial distillation point of the distillation reaches 200°C, it can be used as it is as an ethylene bottom feed oil.
In the ethylene bottom stock oil used in the pitch production in the present invention, other heavy oil such as coal tar or petroleum heavy oil is added in addition to ethylene bottom oil or ethylene bottom oil heavy component as the main component. You may use it.

一般式（１）中、複数のＲはそれぞれ独立して、水素原子、炭素数１〜３のアルキル基または炭素数２〜３のアルケニル基を表す。 Step 1 is a step of preparing an ethylene bottom feedstock by mixing at least an ethylene bottom oil heavy component and dicyclopentadiene. As mentioned above, the ethylene bottom oil heavies may be mixed with the dicyclopentadiene in the form of the ethylene bottom oil containing it.
The dicyclopentadiene may be any of those generally known as dicyclopentadiene obtained by thermal decomposition of petroleum, and in addition to the compound represented by the general formula (1), It also includes the indicated cyclopentadiene compound.

In general formula (1), a plurality of R's each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 3 carbon atoms.

A plurality of R may be the same or different. Examples of the alkyl group having 1 to 3 carbon atoms include methyl group, ethyl group and propyl group. Examples of the alkenyl group having 2 to 3 carbon atoms include vinyl group and allyl group. Among these, a hydrogen atom or an alkyl group having 1 to 2 carbon atoms is preferable, and a hydrogen atom or a methyl group is more preferable, because they are small in size and do not inhibit polycondensation. Examples of such dicyclopentadiene include dicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene and the like. The bonding position of the methyl group may be any carbon atom.

一般式（２）中、複数のＲはそれぞれ独立して水素原子、炭素数１〜３のアルキル基または炭素数２〜３のアルケニル基を表す。
また、一般式（２）で示されるシクロペンタジエン化合物は、ディールズ・アルダー反応により縮合してジシクロペンタジエン化合物を生成し、また、ジシクロペンタジエン化合物の逆ディールズ・アルダー反応により解離して生成する。これら反応は無触媒で進行し、２００℃以上では容易に平衡に達するため、後の工程２の熱処理工程でこれら反応を抑制できない。このようにシクロペンタジエン類はピッチ製造工程中で容易に縮合してジシクロペンタジエン類を生成するため、本発明のジシクロペンタジエン類にはシクロペンタジエン化合物をも含める。

In general formula (2), a plurality of R's each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 3 carbon atoms.
Further, the cyclopentadiene compound represented by the general formula (2) is condensed by the Diels-Alder reaction to produce a dicyclopentadiene compound, and is also dissociated and produced by the reverse Diels-Alder reaction of the dicyclopentadiene compound. Since these reactions proceed without a catalyst and reach equilibrium easily at 200° C. or higher, these reactions cannot be suppressed in the subsequent heat treatment step of step 2. As described above, cyclopentadiene is easily condensed in the pitch manufacturing process to produce dicyclopentadiene, and thus the cyclopentadiene compound of the present invention also includes a cyclopentadiene compound.

A plurality of Rs may be the same or different. Examples of the alkyl group having 1 to 3 carbon atoms include methyl group, ethyl group and propyl group. Examples thereof include an alkenyl group having 2 to 3 carbon atoms, a vinyl group, and an allyl group. Among these, a hydrogen atom or an alkyl group having 1 to 2 carbon atoms is preferable, and a hydrogen atom or a methyl group is more preferable, because they are small in size and do not inhibit polycondensation. Examples of such compounds include cyclopentadiene, methylcyclopentadiene, dimethylcyclopentadiene and the like. The bonding position of the methyl group may be any carbon atom.

The concentration of dicyclopentadiene (when a plurality of types are included, the total amount thereof) is appropriately adjusted within the range of 1 to 30% by mass, preferably 1 to 10% by mass, based on the whole ethylene bottom stock oil. Even when a mixture containing dicyclopentadiene is used as the ethylene bottom stock oil, the ratio of the dicyclopentadiene to the ethylene bottom stock oil is adjusted to fall within the above range. When the concentration of dicyclopentadiene is less than 1% by mass, the molecular weight of the component in the ethylene bottom feedstock is not sufficiently improved, and the yield is not sufficiently improved. On the other hand, if it exceeds 30% by mass, the amount of inexpensive ethylene bottom oil used decreases, which is economically disadvantageous.

As the dicyclopentadiene, the compounds included in the above general formulas (1) and (2) can be used alone, or a mixture of a plurality of compounds can be used to produce an ethylene bottom oil or an ethylene bottom oil heavy component. It can be mixed to obtain an ethylene bottom stock oil. When a mixture containing dicyclopentadiene is used, the proportion of dicyclopentadiene in the mixture is preferably 10% by mass or more, more preferably 20% by mass or more. The component other than the dicyclopentadiene in the mixture containing the dicyclopentadiene is preferably hydrocarbon. Specific examples of the mixture containing such dicyclopentadiene include decomposed kerosene.

Decomposed kerosene is a mixture of unsaturated hydrocarbon compounds mainly having 9 or more carbon atoms, which is produced by a petrochemical industrial process, and is a fraction having a boiling point in the range of 90 to 230° C. at 1 atm. However, since the decomposed kerosene used in the present invention is a mixture of various hydrocarbons, the number of carbon atoms and the boiling point may be slightly changed.

The main components of decomposed kerosene include, for example, xylene, styrene, allylbenzene, propylbenzene, methylethylbenzene, trimethylbenzene, methylstyrene, dicyclopentadiene, indane, indene, methylpropylbenzene, methylpropenylbenzene, ethylstyrene, divinyl. Examples thereof include benzene, methylindene, naphthalene and methyldicyclopentadiene.

The general process of petrochemical industry and the manufacturing process of decomposed kerosene are as shown in FIG. Unlike ethylene bottom oil, cracked kerosene is a product in which thermal decomposition products are once compressed and cooled by a compressor and then separated by distillation. In the process of distillation, cyclopentadiene and the like in the thermal decomposition product cause a Diels-Alder reaction to produce dicyclopentadiene. Therefore, the decomposed kerosene usually contains 10% by mass or more of dicyclopentadiene.

Ethylene bottom oil and cracked kerosene are products with a continuous boiling range in petrochemical processes, but as shown in Fig. 1, they are products manufactured from completely different steps in the petrochemical process, and are usually not mixed. , Used for different purposes. Further, as described above, the ethylene bottom oil contains almost no dicyclopentadiene, but the cracked kerosene contains dicyclopentadiene.

The decomposed kerosene can be used untreated, or can be used by distilling off low-boiling components as appropriate to increase the concentration of dicyclopentadiene. At this time, it should be noted that the dicyclopentadiene is dissociated if the decomposed kerosene is heated too much.

In step 1, an ethylene bottom oil or a heavy ethylene bottom oil and dicyclopentadiene are mixed and appropriately heated and stirred in a molten state to prepare a raw material in which both components are uniformly mixed.

Step 2 is a heat treatment step of heating the ethylene bottom stock oil obtained in Step 1. The heat treatment temperature is, for example, 300 to 450° C., the time is 0.5 to 6 hours, and the heat treatment pressure is 0 to 2 MPaG (gauge pressure). A more preferable heat treatment temperature is 320 to 420°C, and further preferably 340 to 400°C. Further, the heat treatment pressure is more preferably 0 to 1 MPaG, further preferably 0 to 0.8 MPaG. If the heat treatment temperature is too low, the improvement of the molecular weight will be insufficient and the yield will not be sufficiently improved. On the other hand, if it is too high, abnormal polycondensation proceeds and the pitch structure obtained becomes optically anisotropic. If the heat treatment pressure is too high, a pressure resistant heat treatment apparatus is required, which is economically disadvantageous. The heat treatment is preferably carried out under an inert gas such as nitrogen gas, water vapor or carbon dioxide gas. The heat treatment method may be, for example, a batch method using an autoclave or the like, and continuously using a thin film distillation apparatus, a falling film heat treatment apparatus, a rotary disc type dispersion evaporator, etc. under reduced pressure or atmospheric pressure under the flow of an inert gas or the like. You may go to

Step 3 is a distillation step of the heat treatment liquid obtained in Step 2. The low molecular component contained in the liquid obtained in step 2 is distilled off to obtain pitch as a high boiling component from the bottom of the column. The distillation method and conditions are appropriately adjusted depending on the desired softening point of the pitch. Further, the distillation may be carried out in one stage or may be carried out in two or more stages. For example, while bubbling nitrogen gas, distill under normal pressure for 0.5 to 3 hours at 350 to 390° C., then reduce the pressure to 1 to 50 hPa and perform reduced pressure distillation at 350 to 390° C. until there is no distillate. To obtain the pitch from the bottom of the tower.

The pitch produced by the present invention can be realized in a wide variety of compositions and properties. The pitch produced by the present invention is preferably optically isotropic. Further, it is preferably a high softening point pitch having a softening point of 200° C. or higher, more preferably 230° C. or higher.
The pitch obtained in the present invention is useful as a raw material for general-purpose carbon fibers, activated carbon fibers, or isotropic high-density graphite materials used for electrodes, heaters, various crucibles, sliding members, and the like.

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.
[Measurement of dicyclopentadiene concentration]
The concentration of dicyclopentadiene compounds in the decomposed kerosene (total value of each dicyclopentadiene compound) was estimated by the area percentage method using GC-MS. As an analytical instrument, 5975C spectrometer manufactured by Agilent Technology Co., Ltd. was used, and as a column, HP-5MS 5% Phenyl Methyl Siloxane manufactured by Agilent Technology Co., Ltd. was used.

[Measurement of softening point]
The softening point of the manufactured pitch was measured by thermomechanical analysis (TMA; ThermoMechanical Analysis). EXSTAR TMA/SS6300 manufactured by SII Nanotechnology Inc. was used as an analytical instrument. As a sample preparation, 0.5 g of a pitch sample was put into an aluminum pan (capacity 100 μL), and was once softened at a temperature raised by 30° C. from the softening point measured by the hot plate method to generate a flattened pitch surface in the aluminum pan. ..
The TMA measurement conditions were as follows: temperature: room temperature to a maximum of 500° C., temperature rising rate: 5° C./min, nitrogen gas flow rate: 100 cc/min, under an inert atmosphere. Further, a needle-inserted probe was used as the probe, and the probe was pressed from above with a constant force of 49 mN.

The main physical properties of the ethylene bottom oil used in the examples are as follows.
Density: 1.0482 g/cm ³ , kinematic viscosity (50° C.): 19.5 cSt, water content: 2062 volppm (Karl Fischer method, the same applies below), flash point: 80.0° C., initial boiling point: 191° C., 50% distillation Outlet temperature: 259° C., total sulfur concentration: 1444 mass ppm.

The main physical properties of the decomposed kerosene used in the examples are as follows.
Density: 0.9176 g/cm ³ , moisture: 220 volppm, flash point: 36.0° C., initial boiling point: 132° C., 50% distillation temperature: 168° C., total sulfur concentration: 138 mass ppm, of dicyclopentadiene Concentration 12% by mass.

Example 1:
Using 894 kg of ethylene bottom oil as a raw material, a distillation facility having a theoretical plate number of 15 (sulzer packing) was used to distill and refine at a kiln temperature of 101° C. and an operating pressure of 4 to 8 Torr, and an ethylene bottom oil heavy component was obtained as a bottom liquid. Fraction-1 was obtained in an amount of 544 kg. The first distillation point of Fraction-1 was 218°C.
On the other hand, using 500 g of decomposed kerosene as a raw material, a single evaporation at a liquid temperature of 120° C. and an operating pressure of 50 hPa was carried out to obtain 106 g of fraction-2 in which low boiling components were removed and high boiling components were concentrated. The concentration of dicyclopentadiene contained in Fraction-2 was 21% by mass.
As an ethylene bottom feed oil, 95 g of fraction-1 and 5 g of fraction-2 were used, charged into a 100 ml autoclave, and then sufficiently stirred and mixed. The dicyclopentadiene concentration in the feedstock was 1.05% by mass. After purging the gas phase with nitrogen gas, heat treatment was performed at an internal temperature of 370° C. for 30 minutes. The internal pressure at this time reached 0.7 MPaG. The amount of the liquid obtained after the heat treatment was 99 g.
Further, the liquid after the heat treatment was subjected to atmospheric distillation under a nitrogen atmosphere at 370° C. to remove low boiling components. Subsequently, at 370° C., vacuum thin film distillation was performed with an evaporator. At this time, the temperature rising rate was 5° C./min, and the rotation speed was 50 to 100 rpm. 30 g of a pitch having a softening point of 250° C. was obtained as the residue of the kettle. The pitch yield based on the total amount of the fraction-1 and the fraction-2 charged was 30% by mass.
The ethylene bottom feedstock compounding amount, the dicyclopentadiene concentration in the ethylene bottom feedstock, the internal pressure during heat treatment, and the yield and softening point of the obtained pitch are shown in Table 1 together with the results of the following examples. Are summarized in.

Example 2:
The same operation as in Example 1 was performed except that a dicyclopentadiene reagent (Analytical standard) manufactured by Sigma-Aldrich was used instead of the fraction-2. The dicyclopentadiene concentration in the ethylene bottom stock oil was 5% by mass. At this time, the internal pressure reached 0.7 MPaG, and the amount of the liquid obtained after the heat treatment was 98 g. In addition, a pitch of 31 g having a softening point of 250° C. was obtained in the residue after the thin film evaporator treatment. The pitch yield was 31% by mass.

Example 3:
Instead of Fraction-2, a dicyclopentadiene reagent manufactured by Sigma-Aldrich was used, and the same operation as in Example 1 was performed except that the charge amount of Fraction-1 was 70 g and the charge amount of dicyclopentadiene was 30 g. went. The dicyclopentadiene concentration in the ethylene bottom stock oil was 30% by mass. At this time, the internal pressure during the heat treatment reached 0.7 MPaG, and the obtained amount of the liquid after the heat treatment was 99 g. In addition, a pitch of 37 g having a softening point of 250° C. was obtained in the residue after the thin film evaporator treatment. The pitch yield was 37% by mass.

Example 4:
The same operation as in Example 1 was performed, except that the heat treatment was performed in an atmosphere open system container instead of the autoclave. The dicyclopentadiene concentration in the ethylene bottom stock oil was 1.05% by mass. The amount of the liquid obtained after the heat treatment at this time was 74 g. Moreover, 36 g of a pitch having a softening point of 250° C. was obtained in the residue after the treatment with the thin film evaporator. The pitch yield was 36% by mass.

Example 5:
The same operation as in Example 1 was performed, except that the heat treatment was carried out in an apparatus open to the atmosphere instead of the autoclave and the dicyclopentadiene reagent manufactured by Sigma-Aldrich was used instead of the fraction-2. The dicyclopentadiene concentration in the ethylene bottom stock oil was 5% by mass. The amount of the liquid obtained after the heat treatment at this time was 59 g. In addition, a pitch of 30 g with a softening point of 250° C. was obtained in the residue after the thin film evaporator treatment. The pitch yield was 30% by mass.

Comparative Example 1:
The same operation as in Example 1 was performed except that Fraction-2 was not used and 100 g of Fraction-1 was used as the ethylene bottom stock oil. The dicyclopentadiene concentration in the ethylene bottom stock oil was 0% by mass. At this time, the internal pressure during the heat treatment reached 0.7 MPaG, and the obtained amount of the liquid after the heat treatment was 97 g. In addition, a pitch of 23 g with a softening point of 270° C. was obtained in the residue after the thin film evaporator treatment. The pitch yield was 23% by mass.

Comparative Example 2:
The same operation as in Example 1 was carried out except that untreated decomposed kerosene was used in place of Fraction-2. The dicyclopentadiene concentration in the ethylene bottom stock oil was 0.6% by mass. At this time, the internal pressure during the heat treatment reached 0.7 MPaG, and the obtained amount of the liquid after the heat treatment was 96 g. In addition, 21 g of pitch having a softening point of 250° C. was obtained in the residue after the thin film evaporator treatment. The pitch yield was 21% by mass.

Comparative Example 3:
The same operation as in Example 1 was performed except that an indene reagent manufactured by Sigma-Aldrich was used instead of the fraction-2. The dicyclopentadiene concentration in the ethylene bottom stock oil was 0% by mass. At this time, the internal pressure during the heat treatment reached 0.7 MPaG, and the obtained amount of the liquid after the heat treatment was 97 g. In addition, a pitch of 23 g with a softening point of 258° C. was obtained in the residue after the thin film evaporator treatment. The pitch yield was 23% by mass.

Table 1 shows the results of Examples 1 to 5 and Comparative Examples 1 to 3.
As can be seen from the results in Table 1, in Examples 1 to 5 in which the raw material having a dicyclopentadiene concentration of 1% by mass or more was used, compared with Comparative Examples 1 to 3 in which the dicyclopentadiene concentration was less than 1% by mass. Thus, a high pitch yield was achieved. Also, the softening point of the obtained pitch was 200° C. or higher, which was comparable to the pitch obtained in Comparative Example 1 in which only the ethylene bottom oil heavy component was used as the ethylene bottom base stock oil.

Claims (6)

A step of preparing an ethylene bottom base stock oil containing 10 mass% or more of ethylene bottom oil heavy components and 1 to 30 mass% of dicyclopentadiene, a step of heat treating the stock oil (step 2), a heat treatment A method for producing pitch, comprising a step (step 3) of distilling the product to obtain pitch as a high boiling point component. The method for producing a pitch according to claim 1, wherein an ethylene bottom stock oil containing 50 mass% or more of an ethylene bottom oil heavy component is used. Further, the method for producing a pitch according to claim 1 or 2, wherein an ethylene bottom feed oil containing a heavy oil selected from coal tar and a heavy petroleum oil is used. The method for manufacturing a pitch according to claim 1, wherein the heat treatment temperature is 300 to 450° C. 5. The method for manufacturing a pitch according to claim 1, wherein the heat treatment pressure is 0 to 2 MPaG. The method for producing a pitch according to claim 1, wherein at least a part of the dicyclopentadiene is derived from decomposed kerosene.

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