Method for producing mesophase pitch

Abstract

To provide a method of producing mesophase pitch, capable of producing practical mesophase pitch from lignite synthetic oil and petroleum-based residue or a reformed product of the petroleum-based residue as a starting material.SOLUTION: The method of producing mesophase pitch, comprises: a mixing step of mixing a first raw material and a second raw material to obtain mixed raw materials, the first raw material being lignite synthetic oil obtained by subjecting a mixture including lignite and water to a hydrothermal treatment under pressure, the second raw material being hydrogen-donating petroleum-based residue or the reformed product of the petroleum-based residue; a co-pitching step of heating the mixed raw materials under pressure to carry out a co-pitching reaction; a reaction product recovery step of recovering the reaction product obtained by the co-pitching step; and a pitch preparation step of vacuum-distilling the recovered reaction product to prepare mesophase pitch.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing mesophase pitch. [Background technology]

[0002] Coal-based pitch and petroleum-based pitch have been used as raw materials for mesophase pitch for high-performance carbon materials. For example, pitch obtained by modifying coal tar, a by-product of coke production for steelmaking, is known. Also known are pitches obtained by modifying heavy components such as hydrogenation residues from petroleum refining and solvent deasphalting residues. Various electrode materials are produced from needle coke obtained by coking the pitch in a coker.Mesophase carbon fibers are also produced by hot spinning the pitch.

[0003] Various studies have been conducted on methods for producing mesophase pitch to obtain high-performance carbon materials, and methods for producing high-performance carbon materials. For example, Patent Document 1 discloses a method for producing raw material pitch for carbon fiber production, which includes the steps of mixing a first coal having an average maximum vitrinite reflectance Ro of 1 or more, a second coal having an average maximum vitrinite reflectance Ro of less than 1, and an aromatic solvent, and extracting soluble components of the first coal and the second coal from the mixture by heating, wherein the blending ratio of the first coal to the total coal is 30% by mass or more and 70% by mass or less. Patent Document 2 discloses a method for producing carbon fiber, which includes a step of obtaining ashless coal by solvent extraction of coal, a step of hydrogenating the ashless coal, a step of heat-treating the hydrogenated ashless coal, and a step of melt-spinning the heat-treated ashless coal, and in which the molar ratio (H / C) of the hydrogen content to the carbon content of the ashless coal before hydrogenation is 0.91 or less. Patent Document 3 discloses a method including: (1) removing salts and quinoline insolubles from the high-temperature coal tar to obtain a decant oil; (2) subjecting the decant oil to one of two methods: (2a) using the decant oil as a hydrogenation feed oil; or (2b) pre-distilling the decant oil to obtain a bottom component having a boiling point above 230°C, and mixing the bottom component with a modified oil containing one or more components selected from the group consisting of coal tar distillate oil and hydrogenated products of coal tar distillate oil to obtain a hydrogenation feed oil; and catalytically hydrotreating the hydrogenation feed oil to obtain a hydrotreated oil; (3) distilling the hydrotreated oil to obtain a hydrogenated pitch; and (4) thermally polymerizing the hydrogenated pitch to obtain a mesophase pitch. Patent Document 4 discloses a binder pitch having a softening point (SP) of 100°C or higher and lower than 115°C, a quinoline insoluble (QI) content of 12.0% by mass or higher and lower than 20.0% by mass, a fixed carbon (FC) content of 58.0% by mass or higher, and a 360°C fraction of 5.0% by mass or lower. Patent Document 5 discloses a raw material pitch for producing carbon fibers, which is obtained from coal and is used to produce carbon fibers by melt spinning, and is characterized by having an oxygen content of 1.0% by mass or more and a toluene-soluble content of 20% by mass or more. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-95595 [Patent Document 2] Japanese Patent Application Publication No. 2018-16921 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-513320 [Patent Document 4] Japanese Patent Application Publication No. 2017-218486 [Patent Document 5] Japanese Patent Application Laid-Open No. 2016-210925 Summary of the Invention [Problem to be solved by the invention]

[0005] The main suppliers of mesophase pitch are the petroleum refining, steelmaking, and coke manufacturing industries. However, due to a decline in fuel oil demand, a decline in the amount of high-quality coking coal resources and a rise in their prices, and the global shift to cokeless operations with lower GHG emissions, such as electric furnace methods, the supply of pitch, a by-product, is dwindling and it is predicted that it will not be able to meet future demand. In light of this situation, there are attempts to utilize unused lignite. Given its properties, lignite is currently not being fully utilized, despite its abundance in the world and low cost. If such lignite could be used to produce mesophase pitch, it would be possible to make noble use of this unused resource and also hopefully alleviate future shortages of pitch raw materials. The techniques described in Patent Documents 1, 3, and 4 do not pay any attention to the use of lignite. Patent Documents 2 and 5 describe that lignite can be used as a raw material, but do not specifically describe the production of mesophase pitch.

[0006] An object of the present invention is to provide a method for producing mesophase pitch that can produce practical mesophase pitch using lignite synthetic oil and petroleum residue or a modified product of the petroleum residue as starting materials. [Means for solving the problem]

[0007] [1] A method for producing mesophase pitch, comprising: a first feedstock being a lignite synthetic oil obtained by hydrothermal treatment of a mixture containing lignite and water under pressure; a second feedstock being a petroleum residue having hydrogen donating properties or a modified product of the petroleum residue; a mixing step of mixing the first feedstock with the second feedstock to obtain a mixed feedstock; a co-pitching step of heating the mixed feedstock under pressure to perform a co-pitching reaction; a reaction product recovery step of recovering the reaction product obtained in the co-pitching step; and a pitch preparation step of preparing mesophase pitch by vacuum distilling the recovered reaction product.

[0008] [2] The method for producing mesophase pitch according to [1], wherein the co-pitching step is carried out under conditions of 0.5 MPa to 6.4 MPa, 260°C to 450°C, and 30 minutes to 6 hours.

[0009] [3] The method for producing mesophase pitch according to [1] or [2] above, wherein the co-pitching step is carried out while stirring the mixed raw materials.

[0010] [4] The method for producing mesophase pitch according to any one of [1] to [3], wherein the reduced pressure distillation in the pitch preparation step is carried out under conditions of 200 Torr or less, 150°C to 300°C, and 60 minutes to 180 minutes.

[0011] [5] The method for producing mesophase pitch according to any one of [1] to [4], wherein the mixing ratio of the first raw material to the second raw material (the first raw material / the second raw material) in the mixing step is, in mass ratio, 10 / 25 or more and 75 / 25 or less.

[0012] [6] In the method for producing mesophase pitch according to any one of [1] to [5] above, the reaction product recovery step includes a step of dissolving the reaction product obtained in the co-pitching step in a solvent to obtain a solution, and a step of removing impurities from the solution.

[0013] [7] The method for producing mesophase pitch according to any one of [1] to [6], further comprising a carbonization step of carbonizing the produced mesophase pitch.

[0014] [8] The method for producing mesophase pitch according to [7] above, wherein the carbonization step is carried out under conditions where the treatment temperature is 450°C or higher and 650°C or lower, and the treatment temperature is maintained for 30 minutes or higher and 4 hours or lower.

[0015] [9] The method for producing mesophase pitch according to any one of [1] to [8], wherein the petroleum residue is at least one selected from the group consisting of cracked residue produced when heavy crude oil is cracked using a fluid catalytic cracking unit, vacuum distillation residue obtained by further reducing the pressure of atmospheric distillation residue of crude oil and distilling it, residue obtained after extracting heavy fractions from the vacuum distillation residue with propane, and ethylene bottom oil.

[0016]

[10] The method for producing mesophase pitch according to any one of [1] to [9], wherein the mesophase pitch produced has an oxygen atom content of 3.0 mass% or less. [Effects of the Invention]

[0017] According to one aspect of the present invention, it is possible to provide a method for producing mesophase pitch that can produce practical mesophase pitch using lignite synthetic oil and petroleum residue or a modified product of the petroleum residue as starting materials. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram showing an example of a subcritical hydrothermal catalytic reaction process. [Figure 2] 1 is a graph showing distillation curves of brown coal synthetic oils derived from coal A, coal B, and coal C. [Figure 3] 1 is a graph showing fraction ratios of brown coal synthetic oils derived from coal A, coal B, and coal C. [Figure 4] 1 is a polarizing microscope photograph of pitch carbides of Examples 1-1, 1-2, and 1-5. [Figure 5] 3 is a polarizing microscope photograph of pitch carbides of Examples 1-2 to 1-4. [Figure 6]3A to 3C are polarizing microscope photographs of pitch carbides of Examples 1-7 and 1-8. [Figure 7] 1 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. [Figure 8] Schematic diagram of a small carbonization device used to evaluate the performance of steel binders. [Figure 9] Photographs showing the evaluation results when pitch A of Example 1-4 was used as a binder pitch for steel. [Figure 10] 1 is a graph showing weight loss profiles due to steam gasification of the composites produced in Examples 3-1 and 3-2 and the needle coke used in Reference Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0019] In this specification, a numerical range expressed using "to" means a range that includes the number written before "to" as the lower limit and the number written after "to" as the upper limit.

[0020] [First embodiment] The method for producing mesophase pitch according to this embodiment (hereinafter also referred to as the production method of this embodiment) uses a brown coal synthetic oil obtained by hydrothermal treatment of a mixture containing brown coal and water under pressure as a first feedstock, and a petroleum residue having hydrogen donating properties or a modified product of the petroleum residue as a second feedstock. The method includes a mixing step in which the first feedstock and the second feedstock are mixed to obtain a mixed feedstock, a co-pitching step in which the mixed feedstock is heated under pressure to perform a co-pitching reaction, a reaction product recovery step in which the reaction product obtained in the co-pitching step is recovered, and a pitch preparation step in which the recovered reaction product is distilled under reduced pressure to prepare mesophase pitch. The production method of this embodiment produces mesophase pitch by having, in this order, a mixing step for obtaining a mixed raw material, a co-pitching step, a reaction product recovery step, and a pitch preparation step.

[0021] In this specification, "mesophase pitch" refers to pitch that can form an optically anisotropic structure when a carbide obtained by carbonizing pitch (hereinafter also referred to as pitch carbide or simply carbide) is observed under a polarizing microscope. A method for observing pitch carbide under a polarizing microscope is described in the Examples section. Note that "isotropic pitch" refers to pitch that can usually only reveal an optically isotropic structure when pitch carbide is observed under a polarizing microscope.

[0022] In the manufacturing method of this embodiment, a mixed material of a brown coal synthetic oil (first feedstock) produced by a specific process (subcritical hydrothermal catalytic reaction process) and a petroleum residue or a modified product of the petroleum residue (second feedstock) having hydrogen donor properties is used as the feedstock. In the co-pitching process, a thermal reforming reaction of the mixed material proceeds, and in the pitch preparation process, when the reaction product recovered in the reaction product recovery process (preferably a reaction product from which impurities have been removed) is distilled under reduced pressure, light components are separated and a thermal reforming reaction proceeds again. In this way, in the manufacturing method of this embodiment, the mixed feedstock is thermally reformed at least twice, thereby adjusting the pitch structure. As a result, it is believed that a pitch charcoal with a flow structure (i.e., practical use) can be obtained when carbonized. The mesophase pitch obtained by the production method of this embodiment can be used as a high-performance carbon material (for example, needle coke, a binder for steel, a graphite electrode material, etc.). Furthermore, according to the production method of this embodiment, unused lignite can be effectively utilized. Such utilization of lignite is extremely useful from the viewpoint of noble use of unused resources and from the viewpoint of resolving future shortages of pitch raw material.

[0023] First, the lignite, the first raw material, and the second raw material will be described.

[0024] <Lignite> In this specification, lignite refers to coal with a gross calorific value of 5,800 kcal / kg or more and less than 7,300 kcal / kg on a dry and ash-free basis. Bituminous coal refers to coal with a gross calorific value of 8,100 kcal / kg or more and less than 8,400 kcal / kg on a dry and ash-free basis. Subbituminous coal refers to coal with a gross calorific value of 7,300 kcal / kg or more and less than 8,100 kcal / kg on a dry and ash-free basis.

[0025] <First ingredient> In this specification, lignite synthetic oil refers to a synthetic oil derived from lignite, and specifically refers to a synthetic oil obtained by hydrothermally treating a mixture containing lignite and water under pressure. This process of "hydrothermally treating a mixture containing lignite and water under pressure" is also called a subcritical hydrothermal catalytic reaction process. Figure 1 shows an overview of a subcritical hydrothermal catalytic reaction process (hereinafter also referred to as a "Cat-HTR process"). Figure 1 shows an example of a Cat-HTR process. In the Cat-HTR process shown in Figure 1, first, a lignite-water slurry, a mixture of lignite and water, is subjected to subcritical hydrothermal treatment at 240 atmospheres and 350°C in the presence of a catalyst, the pressure is instantly reduced to atmospheric pressure, and gas is separated (approximately 15% by mass, mainly CO2). Water is separated from the resulting reaction product slurry, and further distillation is carried out at 450°C to yield approximately 60% by mass of improved coal and approximately 20% to 30% by mass of lignite synthetic oil. Typically, the yield of coal tar obtained from a coke oven is approximately 7% to 8% by mass, but the yield of lignite synthetic oil obtained by this Cat-HTR process is as high as approximately 20% to 30% by mass. Therefore, according to the production method of this embodiment, lignite can be used more efficiently than when pitch is produced from coal tar. In the Cat-HTR process shown in FIG. 1, the pressure (240 atmospheres), temperature (350°C), pressure when the pressure is instantly reduced (atmospheric pressure), and distillation temperature (450°C) in the subcritical hydrothermal treatment are not limited to these.

[0026] (Properties of brown coal synthetic oil) The proportion of aromatic hydrocarbons contained in the brown coal synthetic oil is usually 40% by mass or more and 60% by mass or less. The proportion of aliphatic hydrocarbons contained in the brown coal synthetic oil is usually 40% by mass or more and 60% by mass or less. The proportions (mass%) of aromatic hydrocarbons and aliphatic hydrocarbons are determined by the known 13 It can be measured by C-NMR. The elemental analysis values ​​of the brown coal synthetic oil are usually 82% by mass to 84% by mass of carbon atoms, 8% by mass to 10% by mass of hydrogen atoms, and 6% by mass to 8% by mass of oxygen atoms. The elemental analysis values ​​can be measured in accordance with JIS M8813 (2004). The boiling point fraction of brown coal synthetic oil is usually 170°C or higher and 620°C or lower.

[0027] Table 1 shows the elemental contents of the lignite synthetic oils produced by the Cat-HTR process using coal A (Indonesian lignite), coal B (Indonesian lignite), and coal C (Indonesian lignite). Hereinafter, the lignite synthetic oils produced by the Cat-HTR process using coal A, coal B, and coal C may be referred to as "coal A-derived lignite synthetic oil," "coal B-derived lignite synthetic oil," and "coal C-derived lignite synthetic oil." Table 2 shows the kinematic viscosity of IFO (Intermediate Fuel Oil) RMG380 (Residual Marine fuel oil) 380mm 2 The following are the main specification values ​​for the synthetic oils (grades 1 / s) and the physical properties of the synthetic oils derived from coal A, coal B, and coal C. Figure 2 shows the distillation curves of the brown coal synthetic oils derived from coal A, coal B, and coal C. Figure 3 shows the fraction proportions of the brown coal synthetic oils derived from coal A, coal B, and coal C.

[0028] [Table 1]

[0029] Explanation of Table 1 <1 indicates less than 1 ppm. n / a indicates not analyzed. DAF stands for dry ash free base.

[0030] [Table 2]

[0031] Explanation of Table 2 <1 indicates less than 1 ppm. n / a indicates not analyzed.

[0032] The brown coal synthetic oil is not limited to the properties shown in Tables 1 to 2 and Figures 1 to 3, as long as it is obtained by a subcritical hydrothermal catalytic reaction process.

[0033] <Second ingredient> In this specification, "petroleum residue" refers to a residue generated in either a petroleum refining process or a petrochemical process. "Petroleum residue having hydrogen donating ability" refers to a petroleum residue that has hydrogen donating ability. "Hydrogen donating ability" refers to the property of easily donating hydrogen to radicals. In the production method of this embodiment, the petroleum residue having hydrogen donating properties is preferably at least one selected from the group consisting of cracked residue (e.g., CLO, etc.) produced when heavy crude oil is cracked using a fluid catalytic cracking unit (FCC), vacuum distillation residue (e.g., VR, etc.) obtained by further reducing the pressure and distilling the atmospheric distillation residue of crude oil, residue (e.g., PDAS, etc.) obtained after extracting a heavy fraction (preferably a heavy fraction suitable for lubricating oil) from the vacuum distillation residue with propane, and ethylene bottom oil. FCC is an abbreviation for Fluid Catalytic Cracking. CLO is an abbreviation for Clarified Oil, also known as cracked residual oil. CLO is also commonly called decant oil and is often used in research on steel binder pitch. VR is an abbreviation for Vacuum Residue, also known as reduced pressure residue. PDAS is an abbreviation for Propane Deasphalted Asphalt, also known as propane deasphalted asphalt. Ethylene bottom oil is a liquid co-produced with ethylene by naphtha cracking, and refers to a heavy fraction having the highest boiling point among naphtha cracked fractions.

[0034] The "improved product of petroleum residue" is preferably a residue obtained by subjecting petroleum residue (preferably CLO) to pressure heat treatment and then distilling the recovered petroleum residue under reduced pressure. Furthermore, the "improved product of petroleum residue" is preferably a light fraction having a softening point of 250°C or less, which is obtained by subjecting petroleum residue (preferably CLO) to pressurized heat treatment and then distilling the recovered petroleum residue under reduced pressure.

[0035] Each step of the manufacturing method of this embodiment will be described.

[0036] <Mixing process> The mixing step is a step of mixing a first feedstock (brown coal synthetic oil) with a second feedstock (petroleum residue having hydrogen donating properties or a modified product of the petroleum residue) to obtain a mixed feedstock. The mixing ratio of the first raw material to the second raw material in the mixing step (the first raw material / the second raw material) is preferably 20 / 80 or more and 80 / 20 or less, more preferably 10 / 25 or more and 75 / 25 or less, and even more preferably 40 / 60 or more and 60 / 40 or less, by mass. The higher the mixing ratio of the second raw material (preferably CLO or a modified CLO), the easier it is to obtain a pitch charcoal having a flow structure, but from the viewpoint of utilizing as much lignite as possible, it is desirable to increase the mixing ratio of the first raw material (brown coal synthetic oil) as much as possible.From the viewpoint of utilizing as much lignite as possible, the mixing ratio of the first raw material to the second raw material in the mixing step (the first raw material / the second raw material) is preferably 40 / 60 or more and 60 / 40 or less in mass ratio. The mixing method is not particularly limited.

[0037] <Co-pitching process> The co-pitching step is a step in which the mixed raw materials are heated under pressure (preferably under N2 pressure) to carry out a co-pitching reaction. The pressure, temperature, temperature rise rate, reaction time, and stirring speed of the mixed raw material in the co-pitching step are preferably within the following ranges from the viewpoint of smoothly progressing the thermal reforming reaction of the mixed raw material.

[0038] ·pressure The pressure in the co-pitching step (suitably N2 pressure) is preferably 0.5 MPa or more and 6.4 MPa or less, more preferably 1.7 MPa or more and 6.2 MPa or less, and even more preferably 3.2 MPa or more and 4.9 MPa or less.

[0039] ·temperature The temperature in the co-pitching step is preferably 260°C or higher and 450°C or lower, more preferably 270°C or higher and 430°C or lower, and even more preferably 280°C or higher and 420°C or lower.

[0040] Heating rate The temperature rise rate 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.

[0041] Reaction time The reaction time in the co-pitching step is preferably 30 minutes or more and 6 hours or less, more preferably 60 minutes or more and 5 hours or less, and even more preferably 2 hours or more and 5 hours or less.

[0042] The co-pitching step is preferably carried out under conditions of 0.2 MPa to 1.0 MPa, 260° C. to 450° C., and 30 minutes to 6 hours.

[0043] - Mixing speed of mixed materials The co-pitching step is preferably carried out while stirring the mixed raw materials. The stirring means is not particularly limited. The stirring speed is preferably 300 rpm or more and 1200 rpm or less, more preferably 500 rpm or more and 1200 rpm or less, and even more preferably 700 rpm or more and 1100 rpm or less.

[0044] The co-pitching step is preferably carried out under an inert gas atmosphere. Examples of the inert gas include nitrogen, helium, and argon. The inert gas may be a single gas or a mixed gas of two or more gases. Nitrogen is preferred as the inert gas.

[0045] <Reaction product recovery process> The reaction product recovery step is a step of recovering the reaction product obtained in the co-pitching step. The reaction product obtained in the co-pitching step contains impurities as well as pitch. Hereinafter, the "reaction product containing pitch and impurities" obtained in the co-pitching step may be referred to as a "pitch-containing material." In the reaction product recovery step, it is preferable to remove impurities from the reaction product (pitch-containing material), for example, by carrying out the impurity removal step described below. In the subsequent pitch preparation step, it is preferable to distill the reaction product from which the impurities have been removed under reduced pressure. The reaction product recovery step is preferably carried out after lowering the temperature of the reaction product (pitch-containing material) obtained in the co-pitching step. The method for recovering the reaction product is not particularly limited, and examples thereof include reduced pressure heating, reduced pressure distillation, atmospheric distillation, solvent extraction, filtration, centrifugation, etc. These methods are preferably carried out in combination from the viewpoint of removing as many impurities as possible.

[0046] In the manufacturing method of this embodiment, the reaction product recovery step preferably includes a step of dissolving the reaction product obtained in the co-pitching step in a solvent to obtain a solution, and a step of removing impurities from the solution.

[0047] (Step of obtaining a solution) Examples of solvents used in the step of obtaining a solution include water, pyridine, tetrahydrofuran (THF), aliphatic hydrocarbons (e.g., pentane and hexane), aromatic hydrocarbons (e.g., toluene and xylene), alcohols (e.g., ethanol), and acetone. These solvents may be used alone or in combination. The solvent used in the step of obtaining a solution is preferably a mixed solvent of water and an organic solvent (e.g., pyridine).

[0048] (Process for removing impurities from the solution) Examples of impurities include solids (such as metals eluted due to corrosion of the reactor), water-soluble impurities (such as chlorides), and, when the mixed raw material contains a catalyst, impurities resulting from the catalyst (such as residual chlorine and residual base). Methods for removing impurities from the solution include the same methods as those for recovering the reaction product (for example, reduced pressure heating, reduced pressure distillation, atmospheric distillation, solvent extraction, filtration, centrifugation, etc.). One example of a method for removing impurities from a solution (impurity removal means) is to filter solid matter from the solution, then remove the solvent from the solution by atmospheric distillation, and then wash the reaction product (pitch-containing material) from which the solvent has been removed with water. Filtration removes solid matter as impurities, while water-soluble impurities are removed with water washing. Thus, it is preferable to combine impurity removal means to remove impurities from a solution. The step of obtaining a solution and the step of removing impurities from the solution may each be carried out multiple times.

[0049] <Homogenization process> The production method of this embodiment preferably includes, after the reaction product recovery step and before the pitch preparation step, a step of dissolving the reaction product (preferably the reaction product from which impurities have been removed) in a solvent again and uniformly dispersing the pitch in the solvent using a dispersing means (homogenization treatment step). The dispersion means is not particularly limited, but ultrasonic dispersion is preferred.

[0050] <Pitch preparation process> The pitch preparation step is a step of preparing mesophase pitch by vacuum distilling the recovered reaction product (preferably a reaction product from which impurities have been removed, more preferably a reaction product from which impurities have been removed and which has been subjected to a homogenization treatment step).Mesophase pitch is obtained by this pitch preparation step. The pressure in the reduced pressure distillation is preferably 200 Torr or less (26664.4 Pa or less), more preferably 100 Torr or less (13332.2 Pa or less), even more preferably 50 Torr or less (6666.1 Pa or less), and even more preferably 10 Torr or less (1333.22 Pa or less). The temperature during the reduced pressure distillation is preferably 150°C or higher and 300°C or lower, and more preferably 180°C or higher and 2700°C or lower. The treatment time for the reduced pressure distillation is preferably 60 minutes or more and 180 minutes or less, and more preferably 90 minutes or more and 150 minutes or less. The treatment time in vacuum distillation is the retention time after the temperature in vacuum distillation is reached. In the pitch preparation step, the reduced pressure distillation is preferably carried out under conditions of 200 Torr or less, 150° C. or more and 300° C. or less, and for 60 minutes or more and 180 minutes or less.

[0051] (Characteristics of mesophase pitch) The content of oxygen atoms in the produced mesophase pitch is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less. The produced mesophase pitch preferably has an aromatic index fa of 0.55 or more, more preferably 0.65 or more, as measured by the Brown-Radner method. The produced mesophase pitch preferably has a ratio (Rn / Ra) of the number of naphthene rings Rn to the number of aromatic rings Ra, which are monocyclic structural parameters, of 0.55 or less, more preferably 0.45 or less. The methods for measuring the oxygen atom content, aromatic index fa, and Rn ratio (Rn / Ra) in mesophase pitch are described in the Examples section.

[0052] Second Embodiment The manufacturing method of the second embodiment differs from the first embodiment in that it further includes a carbonization step (hereinafter also referred to as the "carbonization step"). Since the other points are the same as those of the first embodiment, the description thereof will be omitted or simplified.

[0053] <Carbonization process> The carbonization step is a step in which the produced mesophase pitch is carbonized. The carbonization method is not particularly limited, but may be, for example, a method of heating mesophase pitch under an inert gas atmosphere, such as the inert gases listed in the section on the co-pitch formation step of the first embodiment.

[0054] The treatment temperature, the time for which the treatment temperature is maintained, and the temperature rising rate in the carbonization step are preferably within the following ranges from the viewpoint of smoothly progressing carbonization.

[0055] Processing temperature The treatment temperature in the carbonization step is preferably 450°C or higher and 650°C or lower, more preferably 470°C or higher and 650°C or lower, and even more preferably 500°C or higher and 650°C or lower.

[0056] -Holding time at processing temperature The treatment temperature is maintained for a period of preferably 30 minutes to 4 hours, more preferably 30 minutes to 3 hours, and even more preferably 30 minutes to 2 hours.

[0057] Heating rate The temperature rise rate in the carbonization step is preferably 1° C. / min to 5° C. / min, more preferably 1° C. / min to 4° C. / min, and even more preferably 1° C. / min to 3° C. / min.

[0058] The carbonization step is preferably carried out under conditions where the treatment temperature is 450° C. or higher and 650° C. or lower, and the time for which the treatment temperature is maintained is 30 minutes or higher and 4 hours or lower. The carbonization device is not particularly limited as long as it is capable of carbonizing mesophase pitch in a low-oxygen atmosphere (preferably in an inert gas atmosphere), and known carbonization devices can be used.

[0059] The optical structure of carbonized mesophase pitch (pitch carbide) is considered to be increasingly anisotropic in the order of mosaic structure, flow structure, and domain structure. Table 3 shows an example of a classification of optically anisotropic structures. The classification shown in Table 3 is based on the Proceedings of the 16th Coal Science Conference and the 46th Joint Fuel Association Meeting (1979), pp. 200-206, by Isao Mochida, Shuichi Matsuoka, Keiko Maeda, et al. As shown in Table 3, the mosaic and flow structures are further classified according to size. The mosaic structures are more anisotropic in the order of ultra-fine mosaic, ultra-fine mosaic, fine mosaic, medium mosaic, coarse mosaic, and ultra-coarse mosaic. The flow structures are more anisotropic in the order of coarse flow structures and flow structures. In the production method of this embodiment, the mixing step, the co-pitching step, the reaction product recovery step, the pitch preparation step, and the carbonization step are carried out in this order, thereby producing a pitch carbide having a flow structure, as will be shown in the examples described later. The pitch carbide can be used as a high-performance carbon material.

[0060] [Table 3]

[0061] [Uses of mesophase pitch and pitch carbonized material] The mesophase pitch and pitch carbonized material produced by the production method of this embodiment can be used, for example, as high-performance carbon materials. Mesophase pitch can be suitably used as a high-performance carbon material, taking advantage of the high elasticity and high conductivity of its carbonized form. Examples of high-performance carbon materials include carbon materials produced from needle coke of pitch carbide (e.g., graphite electrode materials, lithium-ion battery negative electrode materials, and carbon materials for capacitors), as well as pitch used as is for carbon fiber raw material pitch and graphite electrode impregnation pitch. Examples of general-purpose carbon materials include use as binders for steel binder pitch. The mesophase pitch and pitch carbonized material produced in the other embodiments described below can also be used as general-purpose carbon materials and high-performance carbon materials.

[0062] Other Embodiments In the manufacturing method of the first or second embodiment, the mixed raw material may further contain a catalyst. The catalyst is preferably a halogen-containing compound. The halogen-containing compound is classified into a halogen-containing organic compound and a halogen-containing inorganic compound. Examples of halogen-containing organic compounds include polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), chlorinated polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, chlorinated polystyrene, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-ethylene chloride copolymer, vinyl chloride-propylene chloride copolymer, vinyl chloride-styrene copolymer, and vinyl chloride-vinyl acetate copolymer. Examples of halogen-containing inorganic compounds include aluminum chloride (AlCl3), aluminum bromide (AlBr3), titanium chloride (TiCl4), zirconium chloride (ZrCl4), antimony fluoride (SbF5), iron chloride (FeCl3), zinc chloride (ZnCl2), boron fluoride (BF3), boron chloride (BCl3), aluminum iodide (AlI3), gallium chloride (GaCl3), gallium bromide (GaBr3), antimony chloride (SbCl5), tin chloride (SnCl2), titanium bromide (TiBr4), zinc bromide (ZnBr2), tin bromide (SnBr2), iron bromide (FeBr3), aluminum fluoride (AlF3), titanium fluoride (TiF4), zinc fluoride (ZnF2), and tin fluoride (SnF2). The halogen-containing compound is preferably polyvinyl chloride (PVC) or aluminum chloride (AlCl3) from the viewpoint of promoting co-pitching of the mixed raw materials. The catalyst content in the mixed raw material is preferably 8% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and even more preferably 0.8% by mass or less. The lower limit is preferably 0.08% by mass or more. When the catalyst content in the mixed raw material is 8% by mass or less, it becomes easier to obtain pitch carbonized material having a flow structure while ensuring the yield of mesophase pitch.

[0063] The present invention is not limited to the above-described embodiment, and any modifications and improvements that can achieve the object of the present invention are included in the present invention. [Example]

[0064] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0065] [Production of mesophase pitch and pitch carbonized product] Example 1-1 The first feedstock used was a brown coal synthetic oil produced by the subcritical hydrothermal catalytic reaction process shown in Figure 1. This brown coal synthetic oil was derived from coal A and has the properties shown in Tables 1 and 2 and Figures 2 and 3. The second feedstock used was a residual oil (CLO) produced when heavy crude oil is cracked using a fluid catalytic cracking unit.

[0066] The brown coal synthetic oil and CLO were mixed so that the mixing ratio (brown coal synthetic oil / CLO) was 10 / 25 by mass (mixing step). The total amount of the mixed raw material of brown coal synthetic oil and CLO was 35 g. The mixed raw materials were charged into an autoclave, and the atmosphere inside the autoclave was replaced with a reaction atmosphere gas (N2 gas) five times, after which the system was kept at room temperature (25°C) and the initial pressure was set to 0.5 MPa. Next, the mixed raw materials were heated to 400°C at a rate of 10°C / min while being stirred at 1000 rpm using a band heater, and then heated at 400°C for 1 hour to co-pitch the mixed raw materials. The pressure during the reaction was controlled within the range of 1.7 MPa to 6.9 MPa (co-pitching process). Next, the band heater was removed, and the reaction product was cooled to 60°C or less with air to degas the system.

[0067] Next, the reaction product was directly recovered and quantified. In addition, deposits on the stirrer and other parts were recovered and quantified using pyridine. The entire amount of recovered reaction product (total amount of directly recovered and deposits) was placed in a recovery flask and dispersed using ultrasound, after which the pyridine was removed by distillation using an evaporator (reaction product recovery step).

[0068] After removing the pyridine, the reaction product (pitch-containing material) was dried, and then the reaction product was dissolved again in pyridine, and the pitch was dispersed in the pyridine using ultrasound (homogenization treatment).

[0069] The solution in which the pitch was dispersed was heated to a temperature of 220°C at a pressure of 1 Torr and a heating rate of 3°C / min, and then distilled under reduced pressure at 220°C for 2 hours (retention time) to remove pyridine and tar from the solution, thereby preparing pitch (pitch preparation step). In this manner, mesophase pitch was obtained.

[0070] A 3 g sample was taken from the obtained mesophase pitch and carbonized under the following conditions to obtain a pitch carbonized product (carbonization step). -conditions- Equipment: Carbonization equipment (manufactured by KRI, equipped with an electrically heated horizontal carbonization furnace) Heating rate: 1.5℃ / min ·Carbonization temperature: 600℃ Holding time: 1 hour Atmospheric gas: Nitrogen (300 mL / min)

[0071] Example 1-2 The mesophase pitch and pitch carbonized product of Example 1-2 were obtained in the same manner as in Example 1-1, except that the brown coal synthetic oil and CLO were mixed so that the mixing ratio of the brown coal synthetic oil and CLO (brown coal synthetic oil / CLO) was 50 / 50 by mass.

[0072] Examples 1-3 The holding time at 220°C in the pitch preparation step was changed from 2 hours to 6 hours so that the softening point (°C) of the mixed raw material of brown coal synthetic oil and CLO would be 115°C. The mesophase pitch and pitch charcoal of Example 1-3 were obtained in the same manner as in Example 1-2, except that a mixed raw material with a softening point adjusted to 115°C was used.

[0073] Examples 1-4 The holding time at 220°C in the pitch preparation step was changed from 2 hours to 8 hours so that the softening point (°C) of the mixed raw material of brown coal synthetic oil and CLO would be 120°C. The mesophase pitch and pitch charcoal of Example 1-4 were obtained in the same manner as in Example 1-2, except that a mixed raw material with a softening point adjusted to 120°C was used. The mesophase pitch of Examples 1-4 is also referred to as "A pitch."

[0074] Examples 1-5 The mesophase pitch and pitch carbonized product of Example 1-5 were obtained in the same manner as in Example 1-1, except that the brown coal synthetic oil and CLO were mixed so that the mixing ratio of the brown coal synthetic oil and CLO (brown coal synthetic oil / CLO) was 75 / 25 by mass.

[0075] Examples 1-6 The mesophase pitch and pitch carbonized product of Example 1-6 were obtained in the same manner as in Example 1-2, except that modified CLO (hereinafter referred to as CLO Modified 1) was used as the second raw material. CLO reformer 1 is a light fraction of CLO reformer 3 with a softening point of 250°C or less. CLO reformer 3 will be described later.

[0076] Examples 1-7 The mesophase pitch and pitch carbonized product of Examples 1-7 were obtained in the same manner as in Examples 1-2, except that the second raw material was CLO modified according to the procedures and conditions shown in Table 4 (hereinafter referred to as CLO Modification 3). The mesophase pitch of Examples 1-7 is also referred to as "Pitch B." CLO Modification 3 was prepared as follows. 50 g of CLO was subjected to pressure heat treatment as shown in Table 4, then cooled and recovered, and then distilled under reduced pressure to obtain modified CLO 3. In Table 4, TOP indicates the top of the distillation column, and BTM indicates the bottom of the distillation column. The same applies to Table 5.

[0077] [Table 4]

[0078] Examples 1-8 As the second raw material, brown coal synthetic oil and CLO modified 3 were mixed so that the mixing ratio (brown coal synthetic oil / CLO modified 3) was 75 / 25 by mass. The mesophase pitch and pitch carbonized material of Examples 1-8 were obtained in the same manner as in Examples 1-7.

[0079] Comparative Example 1-1 The pitch and pitch charcoal of Comparative Example 1-1 were obtained in the same manner as in Example 1-1, except that 5 g of brown coal synthetic oil was used as the raw material.

[0080] Comparative Example 1-2 The raw material used was a mixture of brown coal synthetic oil and PVC. The pitch and pitch carbonized material of Comparative Example 1-2 were obtained in the same manner as in Example 1-1, except that the brown coal synthetic oil and PVC were mixed so that the PVC content was 8.0 mass% per 3 g of brown coal synthetic oil. PVC is a catalyst and is an abbreviation for polyvinyl chloride.

[0081] [Reference example 1-1] As a raw material, only CLO (3 g) was used. Except for this, the pitch and pitch carbide of Reference Example 1-1 were obtained in the same manner as in Example 1-1.

[0082] [Reference example 1-2] As a raw material, only CLO Modified 1 (3 g) was used. Except for this, the pitch and pitch carbide of Reference Example 1-2 were obtained in the same manner as in Example 1-1.

[0083] [Reference example 1-3] Pitch and pitch charcoal of Reference Example 1-3 were obtained in the same manner as in Example 1-1, except that CLO modified according to the procedures and conditions shown in Table 5 (hereinafter referred to as CLO Modification 2) was used as the raw material. CLO Modification 2 was prepared as follows. As shown in Table 5, 50 g of CLO was subjected to pressure heat treatment, cooled, recovered, and then distilled under reduced pressure to obtain modified CLO 2.

[0084] [Table 5]

[0085] [Reference example 1-4] As a raw material, only CLO Modified 3 (3 g) was used. Except for this, the pitch and pitch carbide of Reference Example 1-4 were obtained in the same manner as in Example 1-1.

[0086] 〔evaluation〕 The mesophase pitch yield and pitch char yield were determined. Hereinafter, mesophase pitch may be referred to as pitch, and mesophase pitch yield may be referred to as pitch yield.

[0087] <Pitch yield and pitch carbide yield> Pitch yield (Y p ), pitch char yield (based on pitch) (Y1) and pitch char yield (based on raw material) (Y2) were calculated by the following method. All yields were calculated excluding ash. p), pitch carbide yield (based on pitch) (Y1) and pitch carbide yield (based on raw material) (Y2) are yields on an ash-free basis. The results are shown in Table 6.

[0088] [Measurement of ash content] The ash content of the raw material, pitch, and pitch carbonized product was measured under the following conditions: The ash content on a dry mass basis was calculated using the following formula (10). Ash content based on dry mass [wt%] = W ash / W dry ×100…(10) W dry :120℃ dry mass [g] W ash : Combustion ash mass [g] -conditions- Apparatus: Differential thermobalance TG-DTA (manufactured by Mac Science) Atmosphere: Air, 200mL / min ·120℃ dry mass W dry Temperature conditions Heating rate: 10℃ / min, from room temperature (25℃) to 120℃ Holding time: 120℃, 20min Combustion ash mass W ash Temperature conditions Heating rate: 10℃ / min, from 120℃ to 950℃

[0089] Pitch yield (Y p ) Pitch yield (Y p ) was calculated using equation (1). Y P (wt%)={W2*(100-A P ) / 100} / {W1*(100-A0) / 100}…(1) W1: Amount of raw material input (g) W2: Pitch yield (g) A0: Ash content of raw material (wt%) A P : Ash content of pitch (wt%)

[0090] [Pitch carbide yield (based on pitch) (Y1)] The pitch char yield (Y1) was calculated by the formula (2). Y1(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%) A C : Ash content of pitch carbonized material (wt%)

[0091] [Yield of pitch char (based on raw material) (Y2)] The pitch char yield (Y2) was calculated from the results of the above formulas (1) and (2) using formula (3). Y2(wt%) = Y P ×Y1 / 100…(3) Y P : Pitch yield (wt%) calculated by the above formula (1) Y1: Pitch carbide yield (based on pitch) (wt%) calculated using the above formula (2)

[0092] [Table 6]

[0093] The pitch char yields (based on pitch) (Y1) of Examples 1-2 to 1-8 tended to be almost equal to or greater than the pitch char yields (based on pitch) (Y1) of Reference Examples 1-2 and 1-4, which used CLO Modification 1 and CLO Modification 3 as raw materials.

[0094] <Optical structure of pitch carbide> The pitch carbide was observed using a polarizing microscope (DM2700P, manufactured by Leica Microsystems) in the following manner. A 0.5 g sample was taken from the pitch carbide obtained in each example, and this sample was covered with resin, which was then polished off to prepare a sample for microscopic observation. The polarizing microscope was set in a crossed Nicol position, and a quartz test plate was inserted to observe the sample for microscopic observation.

[0095] FIG. 4 is a polarizing microscope photograph of the pitch carbides of Examples 1-1, 1-2, and 1-5 (magnifications of 100x and 500x). FIG. 5 is a polarizing microscope photograph of the pitch carbides of Examples 1-2 to 1-4 (magnifications of 100x and 500x). FIG. 6 is a polarizing microscope photograph of the pitch carbides of Examples 1-7 and 1-8 (magnifications of 100x and 500x). The pitch carbide of Example 1-1 had a flow structure over the entire surface, and the pitch carbides of Examples 1-2 to 1-4 and 1-7 to 1-8 had a flow structure over almost the entire surface. The pitch carbide of Example 1-5 had a flow structure almost entirely, although the quality and width of the flow were small.

[0096] <Structural analysis> (Aromatic index fa, number of aromatic rings Ra, number of naphthenic rings Rn, and ratio Rn / Ra) 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 Brown-Ladner method (hereinafter also referred to as the BL method). The results are shown in Table 7. The aromatic index fa was calculated by using the soluble fraction of 0.1 g of pitch in a mixed solvent of THF and pyridine (1:1). 1 Aromatic hydrogen (Ha) and aliphatic hydrogens at the α-, β-, and γ-positions (Hα, Hβ, and Hγ) were calculated from the chemical shift peaks obtained by H-NMR (Bruker Japan, product number: DRX500). The number of rings in the average structure in Table 7 was calculated by calculating the aromatic hydrogen (Ha) and aliphatic hydrogen (Hα, Hβ, and Hγ) in the same manner as for the aromatic index fa, and further adding data on molecular weight distribution based on elemental analysis (JIS M8813 (2004)) and gel permeation chromatography (GPC) (Tosoh Corporation, HLC-8220 type)).

[0097] (Relationship between the ratio of naphthenic ring number to aromatic ring number (Rn / Ra) and aromatic index fa) FIG. 7 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.

[0098] [Table 7]

[0099] 7, the pitch A of Example 1-4 and the pitch B of Example 1-7 exhibited higher aromatic index fa values ​​than the pitches of Comparative Examples 1-1 and 1-2 and Reference Example 1-1. As shown in FIG. 7, pitch A of Example 1-4 and pitch B of Example 1-7 exhibited aromatic index fa and Rn / Ra values ​​nearly equivalent to those of mesophase pitch of Reference Example 1-4 (CLO modified 3).

[0100] [Evaluation of use as a binder pitch for steel] The pitch A of Example 1-4 was used as a binder pitch for steel, and its performance was evaluated. FIG. 8 is a schematic diagram of a small carbonization apparatus (50 kg furnace) used to evaluate the performance of the steel binder. For Examples 2-1 to 2-2 and Reference Examples 2-2 and 2-4, in the 50 kg furnace test, a binder was added to 1 kg of coal so that the binder content was 3% by mass, and then co-carbonized.In the test tube test, a binder was added to 3 g of coal so that the binder content was 3% by mass, and then co-carbonized. For Reference Examples 2-1 and 2-3, 1 kg of pure coal was carbonized in the 50 kg furnace test, and 3 g of pure coal was carbonized in the test tube test.

[0101] Example 2-1 Canadian semi-hard coking coal CV coal (hereinafter also referred to as CV coal) was co-carbonized with A pitch added so that the A pitch was 3 mass %. The obtained carbonized product was used for evaluation.

[0102] [Reference example 2-1] CV charcoal was carbonized alone and the carbonized product was used for evaluation.

[0103] [Reference example 2-2] A commercially available binder pitch for steel (hereinafter referred to as ASP) was added to the CV coal so that the amount of ASP was 3 mass %, and the CV coal was co-carbonized. The obtained charcoal was used for evaluation.

[0104] Example 2-2 Australian semi-soft BB coal (hereinafter also referred to as BB coal) was co-carbonized with A pitch added so that the A pitch was 3 mass %. The obtained carbonized product was used for evaluation.

[0105] [Reference example 2-3] BB coal was carbonized alone and the carbonized product was used for evaluation.

[0106] [Reference example 2-4] BB coal was co-carbonized with commercially available binder pitch (ASP) for steel making, with the ASP added to a concentration of 3 mass%. The resulting charcoal was used for evaluation.

[0107] 〔evaluation〕 The mixtures of Examples 2-1 and 2-2, Reference Examples 2-2 and 2-4, and the coals of Reference Examples 2-1 and 2-3 were carbonized under the following conditions and evaluated as follows. The results are shown in Table 8 and FIG.

[0108] (Carbonization conditions) Equipment: Small carbonization equipment shown in Figure 8 (50 kg furnace test) Heating rate: 1.5℃ / min Heat treatment temperature: 1000℃

[0109] (CRI and CSR) CRI (Coke Reactivity Index) and CSR (Coke Strength after Reaction) are considered to be indicators of the hot strength of coke. CRI and CSR were measured using the Nippon Steel method. Specifically, they were measured as follows.

[0110] (CRI measurement) A 200 g sample with a particle size of 20±1 mm was reacted with CO2 at a reaction temperature of 1100°C for 2 hours, then removed and cooled. The mass A (g) of the remaining sample (post-reaction sample) was measured, and the CRI was calculated using the following formula (number 100). CRI(%)=((200-A) / 200)×100…(number 100)

[0111] (Measurement of CSR) The "mass A (g) of the sample after reaction" used in the CRI measurement was introduced into an I-type drum (inner diameter 130 mm × length 700 mm) and rotated at 20 rpm for 30 minutes. After that, the sample was sieved using a standard sieve (9.52 mm). The mass B (g) of the sample remaining on the sieve was measured, and the CSR was calculated using the following formula (Equation 101). CSR(%)=(B / A)×100…(Number 101)

[0112] (Apparent density and true density) The apparent density and true density were measured according to JIS K 2151 (2004).

[0113] [Table 8]

[0114] Explanation in Table 8 The test tube test is a basic test conducted prior to the 50 kg furnace test. Because carbonization is performed using a test tube, the yield and properties of the charcoal can be obtained with a small sample. In the 50 kg furnace test, a lump sample is produced to be used for strength tests such as CRI and CSR, which cannot be obtained with a small sample. ·db indicates dry basis.

[0115] As shown in Table 8, the semi-coke made by adding A pitch to CV coal (Example 2-1) was able to improve the hot strength (CRI and CSR) to an equal or greater extent than the semi-coke made by adding commercially available ASP to CV coal (Reference Example 2-2). The semi-coke made by adding A pitch to BB coal (Example 2-2) achieved hot strength (CRI and CSR) equivalent to that of the semi-coke made by adding commercially available ASP to BB coal (Reference Example 2-4). As shown in FIG. 9, no difference in appearance was observed between the semi-coke made by adding A pitch to CV coal (Example 2-1) and the semi-coke made by adding commercially available ASP (Reference Example 2-2). Similarly, no difference in appearance was observed between the semi-coke made by adding A pitch to BB coal (Example 2-2) and the semi-coke made by adding commercially available ASP (Reference Example 2-4).

[0116] [Evaluation of graphite material applications] The B pitch of Examples 1-7 was used as the graphite material, and the degree of graphitization was evaluated.

[0117] Example 3-1 Of 7.5 g of B pitch (softening point: 160°C to 162°C), 6.00 g (80 wt%) was carbonized under the first carbonization conditions. Of the 7.5 g of B pitch, 1.50 g (20 wt%) was dissolved in 5 mL of chloroform and pulverized in a mortar. 1.50 g of the pulverized B pitch was used as binder 1.

[0118] (First carbonization condition) Equipment: Three-stage temperature control horizontal tubular electric furnace (quartz reaction tube, inner diameter 40 mm x 800 mm) Heating rate: 1.5℃ / min from 140℃ to 600℃ Temperature: 600℃ for 2 hours

[0119] The B pitch carbonized under the first carbonization conditions was crushed in a mortar to 250 μm or less. 6.00 g of the crushed B pitch was designated as aggregate 1. Aggregate 1 and binder 1 were mixed and kneaded in a ratio of 80:20, dried, and then molded under molding condition 1.

[0120] (Molding condition 1) ·Temperature: 190℃ Pressure: 30MPa Time: 5 minutes

[0121] After molding, the mixture was cooled and the pressure was gradually reduced to atmospheric pressure. The formed carbon molded product (hereinafter also referred to as C / C composite) was carbonized under the second carbonization conditions, in which the heating rate in the softening and melting range of B pitch (250°C to 550°C) was reduced to 0.08°C / min.

[0122] (Second carbonization conditions) Equipment: Three-stage temperature control horizontal tubular electric furnace (quartz reaction tube, inner diameter 40 mm x 800 mm) Heating rate: 20℃ to 140℃ at 5℃ / min Heating from 140℃ to 250℃ at 1.5℃ / min Heating from 250℃ to 550℃ at 0.08℃ / min Heating from 550℃ to 800℃ at 5℃ / min Temperature: 800°C for 10 minutes

[0123] Then, the C / C composite was graphitized under graphitization condition 1. The graphitized C / C composite is designated as "C / C-1 (1600°C)."

[0124] (Graphitization condition 1) Equipment: Direct current ultra-high temperature graphitization furnace (HHP) from IHI Machinery Systems Co., Ltd. Heating rate: 20℃ to 800℃ at 25℃ / min Heating from 800℃ to 1600℃ at 5℃ / min Temperature: 1600℃ for 30 minutes

[0125] Example 3-2 A graphitized C / C composite was obtained in the same manner as in Example 3-1, except that graphitization condition 1 was changed to graphitization condition 2. The graphitized C / C composite in Example 3-2 is referred to as "C / C-1 (2800°C)."

[0126] (Graphitization condition 2) Equipment: Direct current ultra-high temperature graphitization furnace (HHP) from IHI Machinery Systems Co., Ltd. Heating rate: 20℃ to 800℃ at 25℃ / min Heating from 800℃ to 2800℃ at 5℃ / min Temperature: 2800℃ for 30 minutes

[0127] Example 3-3 A graphitized C / C composite was obtained in the same manner as in Example 3-1, except that the B pitch carbonized under the first carbonization conditions was pulverized to approximately 10 μm in an agate mortar, the second carbonization conditions were changed to second carbonization conditions A, and graphitization conditions 1 were changed to graphitization conditions 2 in Example 3-2. Under the second carbonization conditions, the heating rate in the softening and melting range of the B pitch (250°C to 550°C) was reduced to 0.08°C / min. The graphitized C / C composite in Example 3-3 is referred to as "C / C-2 (2800°C)".

[0128] (Second carbonization condition A) Equipment: Three-stage temperature control horizontal tubular electric furnace (quartz reaction tube, inner diameter 40 mm x 800 mm) Heating rate: 20℃ to 140℃ at 5℃ / min Heating from 140℃ to 250℃ at 1.5℃ / min Heating from 250℃ to 550℃ at 0.08℃ / min Heating from 550℃ to 800℃ at 5℃ / min Temperature: 800°C for 10 minutes

[0129] [Example 3-4] Of 7.5 g of B pitch (softening point: 160°C to 162°C), 5.25 g (70 wt%) was carbonized under the first carbonization conditions of Example 3-1. Of the 7.5 g of B pitch, 2.25 g (30 wt%) was dissolved in 5 mL of chloroform and pulverized in a mortar. 2.25 g of the pulverized B pitch was designated as binder 2.

[0130] The B pitch carbonized under the first carbonization conditions was pulverized to about 10 μm in a mortar. 5.25 g of the pulverized B pitch was used as aggregate 2. Aggregate 2 and binder 2 were mixed and kneaded, dried, and then molded under molding condition 1 of Example 3-1. After molding, the mixture was cooled and the pressure was reduced stepwise to atmospheric pressure. The formed carbon molded product (C / C composite) was carbonized under the second carbonization condition A of Example 3-3. Thereafter, the C / C composite was graphitized under the graphitization condition 2 in Example 3-2. The graphitized C / C composite in Example 3-4 is referred to as "C / C-3 (2800°C)."

[0131] 〔evaluation〕 The C / C composites obtained in Examples 3-1 to 3-4 were evaluated as follows.

[0132] (Appearance, bulk density, and true density) Table 9 shows the appearance, bulk density, and true density of the C / C composites obtained in Examples 3-1 to 3-4.

[0133] [Table 9]

[0134] As shown in Table 9, the bulk density and true density of the C / C composite increased with increasing heat treatment temperature. The C / C composites of Examples 3-2 to 3-4, which were graphitized at 2800°C, had a true density (2.1745 g / m 3 More than 2.2099g / m 3 The true density of the commercially available graphite electrode (2.22 g / m 3 More than 2.25g / m 3 (See below)

[0135] (graphite crystallite spacing, lattice constant, and crystallite size) The interplanar spacing, lattice constant, and crystallite size of graphite crystallites were measured using XRD (X-ray Diffraction Analysis). I is d 002The values ​​were calculated using the following mathematical formula (1) proposed by BE Warren et al. For XRD, a SmartLab manufactured by Rigaku Corporation was used. The results are shown in Table 10.

[0136]

number

[0137] [Table 10]

[0138] In Example 3-1, for comparison with needle coke, the C / C composite was calcined at the same heat treatment temperature (1600°C) as needle coke, and the degree of graphitization was low. The C / C composites of Examples 3-2 to 3-4 were graphitized at 2800°C, and the graphitization degree P I It was confirmed that the σ is between 0.83 and 0.84, and the crystallite size Lc is between 852 Å and 994 Å, which are almost equivalent to the specifications of artificial graphite.

[0139] [Evaluation of application as needle coke material] (Weight loss profile due to steam gasification) FIG. 10 shows the weight loss profiles by steam gasification (CASGa method; Carbon Analysis by Steam Gasification) of the C / C composite produced in Example 3-1 (C / C-1 (1600°C)), the C / C composite produced in Example 3-2 (C / C-1 (2800°C)), a coal-based needle coke made in Japan that was heat-treated at 1600°C (hereinafter also referred to as coal-based NC (made in Japan)), and a coal-based needle coke made in China that was heat-treated at 1600°C (hereinafter also referred to as coal-based NC (made in China)). Table 11 shows the properties of C / C-1 (1600°C), C / C-1 (2800°C), coal-based NC (made in Japan), and coal-based NC (made in China).

[0140] The CASGa method, developed by KRI Corporation, is a method for identifying carbonaceous materials based on differences in steam gasification reactivity using a thermobalance. The higher the weight loss onset temperature, the lower the reactivity, and the closer the slope is to a vertical, the more uniform the carbon material is, making it a simple method for identifying carbonaceous materials. The Japanese-made needle coke and Chinese-made needle coke used in Reference Examples 1 and 2 were calcined at 1600°C. The CASGa method evaluates T1 (5% weight loss temperature), T2 (95% weight loss temperature), and the difference between these temperatures, ΔT. The more components with fast reactivity, the lower T1; the more components with slow reactivity, the higher T2; and the larger ΔT, the more heterogeneous the carbonaceous material. As shown in Figure 10, among C / C-1 (1600°C), coal-based NC (made in Japan), and coal-based NC (made in China), which all have the same thermal history of 1600°C, C / C-1 (1600°C) and coal-based NC (made in Japan) have roughly the same carbonaceous quality and uniformity, while coal-based NC (made in China) is thought to be reactive and heterogeneous. Therefore, it is considered that C / C-1 (1600°C) produced in Example 3-1 is superior to coal-based NC (made in China) and is equivalent to coal-based NC (made in Japan).

[0141] [Table 11]

[0142] Explanation of Table 11 "-" indicates that no measurement was performed. [Industrial Applicability]

[0143] The production method of the present invention is a method for producing mesophase pitch using lignite, which is often unused, as a raw material. The produced pitch can be used for high-performance carbon materials, etc., and therefore the production method of the present invention has industrial applicability.

Claims

1. A first feedstock is a lignite synthetic oil obtained by subjecting a mixture containing lignite and water to hydrothermal treatment under pressure, and a second feedstock is a petroleum residue having hydrogen donating properties or a modified product of the petroleum residue, a mixing step of mixing the first raw material and the second raw material to obtain a mixed raw material; a co-pitching step in which the mixed raw material is heated under pressure to carry out a co-pitching reaction; a reaction product recovery step of recovering the reaction product obtained in the co-pitching step; and a pitch preparation step of preparing mesophase pitch by vacuum distilling the recovered reaction product. A method for producing mesophase pitch.

2. The method for producing mesophase pitch according to claim 1, The co-pitching step is carried out under conditions of 0.5 MPa or more and 6.4 MPa or less, 260 ° C or more and 450 ° C or less, and 30 minutes or more and 6 hours or less. A method for producing mesophase pitch.

3. The method for producing mesophase pitch according to claim 1 or 2, The co-pitching step is carried out while stirring the mixed raw material. A method for producing mesophase pitch.

4. The method for producing mesophase pitch according to claim 1 or 2, The reduced pressure distillation in the pitch preparation step is carried out under conditions of 200 Torr or less, 150°C or more and 300°C or less, and 60 minutes or more and 180 minutes or less. A method for producing mesophase pitch.

5. The method for producing mesophase pitch according to claim 1 or 2, a mixing ratio (first raw material / second raw material) of the first raw material and the second raw material in the mixing step is 10 / 25 or more and 75 / 25 or less by mass ratio; A method for producing mesophase pitch.

6. The method for producing mesophase pitch according to claim 1 or 2, The reaction product recovery step includes: dissolving the reaction product obtained in the co-pitching step in a solvent to obtain a solution; and removing impurities from the solution. A method for producing mesophase pitch.

7. The method for producing mesophase pitch according to claim 1 or 2, The method for producing mesophase pitch further comprises a carbonization step of carbonizing the produced mesophase pitch.

8. The method for producing mesophase pitch according to claim 7, The carbonization step is carried out under the conditions of a treatment temperature of 450°C or higher and 650°C or lower, and a holding time at the treatment temperature of 30 minutes or higher and 4 hours or lower. A method for producing mesophase pitch.

9. The method for producing mesophase pitch according to claim 1 or 2, The petroleum residue is at least one selected from the group consisting of cracked residue produced when heavy crude oil is cracked using a fluid catalytic cracking unit, vacuum distillation residue obtained by further reducing the pressure of atmospheric distillation residue of crude oil and distilling it, residue obtained after extracting a heavy fraction from the vacuum distillation residue with propane, and ethylene bottom oil. A method for producing mesophase pitch.

10. The method for producing mesophase pitch according to claim 1 or 2, The content of oxygen atoms in the produced mesophase pitch is 3.0% by mass or less. A method for producing mesophase pitch.

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