Method for preparing high purity asphalt

Abstract

The present invention provides a method for preparing high-purity asphalt, which is used for preparing high-purity asphalt of carbon raw material raw materials, the preparation method comprising: a step of preparing soft asphalt with a softening point of 10°C to 60°C; a step of mixing the above-mentioned soft asphalt and an aromatic insoluble coagulation solvent to prepare a mixture; a step of separating a supernatant portion not containing insoluble matter and a precipitate portion containing insoluble matter from the above-mentioned mixture by centrifugation or decantation; and a step of removing the above-mentioned aromatic insoluble coagulation solvent from the above-mentioned supernatant portion not containing insoluble matter by distillation to obtain high-purity asphalt, wherein the ratio of the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin to the total content of quinoline soluble-toluene insoluble matter as β resin is less than 0.65.

Description

Technical Field

[0001] The present invention relates to high-purity pitch for carbon raw material feedstock and a method for preparing the same. Background Art

[0002] Although filtration has been introduced as a method for removing insoluble substances from coal tar, carbon black raw oil, coal tar pitch, etc., the filtration method uses excessive solvent, has a low filtration rate, and is not practical due to problems such as loading. Usually, static sedimentation is used to remove insoluble substances.

[0003] When the static sedimentation method is used to remove insolubles, a high temperature of more than 150°C is required. The solvent used to guide the coagulation of insolubles or reduce the viscosity of the raw asphalt mainly uses a solvent of aliphatic components, for example, n-hexane, petroleum naphtha, kerosene and diesel are mainly used, or aromatic oils are mixed in such aliphatic solvents for use (Japanese Patent JP 52-028501, JP 52-078201, U.S. Patent US4127472). However, if an aliphatic solvent is used to remove quinoline insolubles (QI), there is a problem that the β resin, which is a substance that is conducive to the growth of anisotropic structures in coal tar pitch, is removed together with the insolubles, and the amount of asphalt recovered is substantially reduced relative to the raw material.

[0004] As described above, in order to produce high-quality asphalt from which insoluble matter has been removed, the existing technology for preparing high-purity asphalt based on static sedimentation uses a single aliphatic solvent or a mixture of an aliphatic solvent and an aromatic solvent to induce the coagulation of insoluble matter. However, due to the physical properties of the solvent itself, the asphalt obtained after removing the insoluble matter has poor quality or low recovery rate, and the process becomes complicated.

[0005] It is also known that in the method of preparing high-purity asphalt by removing insolubles from asphalt by decantation or centrifugation, the use of aromatic solvents has the advantage of increasing the recovery rate of asphalt and the recovery rate of β resin. However, among the β resin components, the tetrahydrofuran-soluble-toluene-insoluble components, especially the hard β resin, have been confirmed to have a better influence on the physical properties of the carbon raw material than the quinoline-soluble-tetrahydrofuran-insoluble components, which are heavy β resins. Therefore, the present invention provides a method for preparing high-purity asphalt with a high hard β resin component ratio. Summary of the invention

[0006] Problems to be solved by the invention

[0007] One embodiment of the present invention provides a pitch excellent in quality for use as a raw material for high-quality carbon products, by removing insoluble materials such as quinoline insolubles and reducing the content of quinoline soluble-tetrahydrofuran insolubles as a heavy beta resin.

[0008] Another embodiment of the present invention provides a method for stably producing high-quality pitch for high-quality carbon product raw materials at high purity by removing insoluble materials such as quinoline insolubles and reducing the content of quinoline soluble-tetrahydrofuran insolubles as heavy β resin.

[0009] Solutions for solving problems

[0010] In one example of the present invention, a method for preparing high-purity asphalt for carbon raw material raw materials is provided, and the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials includes: a step of preparing soft asphalt having a softening point of 10°C to 60°C; a step of mixing the above-mentioned soft asphalt and an aromatic insoluble matter condensing solvent to prepare a mixture; a step of separating a supernatant portion not containing insoluble matter and a precipitate portion containing insoluble matter from the above-mentioned mixture by centrifugation or decantation; and a step of removing the above-mentioned aromatic insoluble matter condensing solvent from the above-mentioned supernatant portion not containing insoluble matter by distillation to obtain high-purity asphalt, wherein the ratio of the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin to the total content of quinoline soluble-toluene insoluble matter as β resin is less than 0.65.

[0011] In the above-mentioned high-purity pitch for carbon raw material, the content of quinoline insoluble matter may be 0.05% or less.

[0012] In the above-mentioned high-purity pitch for carbon raw material, the ash content may be 0.02% or less, and the weight ratio of quinoline soluble-toluene insoluble matter as β resin to quinoline insoluble matter may be 60 to 10,000.

[0013] The above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials may also include the following steps: distilling coal tar or carbon black oil to obtain soft asphalt with a softening point of 10°C to 60°C, or mixing creosote oil with a binder asphalt with a softening point of 60°C to 150°C to prepare soft asphalt with a softening point of 10°C to 60°C.

[0014] The above-mentioned aromatic insoluble matter condensation solvent can be a mixed solvent containing more than 90 weight percent of substituted or unsubstituted aromatic compounds formed by a ring or a combination of more than one of them. The situation where the above-mentioned aromatic compound is substituted can be that at least one hydrogen atom of the above-mentioned compound is substituted by a substituent selected from the group consisting of C1-C4 alkyl, halogen atoms, -SH, -NH2, -OH and their combinations, and two or more of the above-mentioned substituents are fused to form a condensed ring.

[0015] The above-mentioned aromatic insoluble matter condensing solvent can be a solvent selected from the group consisting of phenol oil, coke oven light oil and a combination thereof. The above-mentioned phenol oil and coke oven light oil (COKE OVEN LIGHT OIL) are produced in the distillation process of benzene, toluene, xylene, phenol, aniline, thiophenol (THIOPHENOL), chlorobenzene, fluorobenzene and coal tar.

[0016] In the method for preparing the high-purity pitch for carbon raw material, 35 to 150 parts by weight of the aromatic insoluble matter coagulating solvent may be included based on 100 parts by weight of the soft pitch.

[0017] The steps of mixing the soft asphalt and the aromatic insoluble matter coagulation solvent and separating the mixture by centrifugal separation or decantation can be achieved at a temperature of 40°C to 110°C.

[0018] The mixture including the soft asphalt and the aromatic insoluble matter coagulating solvent may have a viscosity of 60 cP or less at a temperature of 70°C.

[0019] The recovery rate of the asphalt obtained by the method for preparing the high-purity asphalt for carbon raw material can be 80 weight percent or more relative to the soft asphalt as the raw material.

[0020] In another example of the present invention, a high-purity asphalt for a carbon raw material is provided, in which the ratio of the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin to the total content of quinoline soluble-toluene insoluble matter as β resin is below 0.65.

[0021] In the above-mentioned high-purity pitch for carbon raw material, the content of quinoline insoluble matter may be 0.05% or less.

[0022] In the above-mentioned high-purity pitch for carbon raw material, the ash content may be 0.02% or less, and the weight ratio of quinoline soluble-toluene insoluble matter as β resin to quinoline insoluble matter may be 60 to 10,000.

[0023] Effects of the Invention

[0024] The β-resin content of the asphalt for carbon product raw materials obtained by the above-mentioned method for preparing high-purity asphalt for carbon raw materials can become a raw material for preparing high-quality carbon products due to its high recovery rate, especially because the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β-resin is low. In addition, since more than 80% of high-purity asphalt can be recovered relative to the raw asphalt with the help of the above-mentioned process, it has economical effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A block diagram showing the steps of a method for preparing high-purity pitch for carbon raw material feedstock according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. The present invention can be implemented in many different ways and is not limited to the embodiments described herein.

[0027] In the present specification, unless otherwise defined, "substituted" means substituted with a C1-C4 alkyl group, a halogen atom, -SH, -NH2, -OH, or a combination thereof.

[0028] In the present specification, unless otherwise defined, "a combination thereof" means that two or more substituents are combined via a linkage group or two or more substituents are combined in a condensed manner.

[0029] In the present specification, in the absence of a separate definition, "alkyl" means the following: a "saturated alkyl" that does not contain any alkenyl or alkynyl group; or an "unsaturated alkyl" that contains at least one alkenyl or alkynyl group. The above-mentioned "alkenyl" means a substituent having at least two carbon atoms forming at least one carbon-carbon double bond, and "alkynyl" means a substituent having at least two carbon atoms forming a carbon-carbon triple bond. The above-mentioned alkyl group may be branched, straight-chain or cyclic.

[0030] For example, C1 to C4 alkyl means that there are 1 to 4 carbon atoms in the alkane chain, which means that the C1 to C4 alkyl is selected from the group consisting of methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl.

[0031] Typical alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, vinyl, propenyl, butenyl, cyclopropyl and cyclobutyl.

[0032] In the present specification, "aromatic compound" means a compound including a cyclic ring, in which all elements in the ring have P-orbitals and these P-orbitals form a conjugation. Specific examples include aryl groups and heteroaryl groups.

[0033] "Aryl" includes single rings or fused rings (ie, multiple rings separating adjacent pairs of carbon atoms).

[0034] The "heteroaryl group" means an aryl group containing one to three heteroatoms selected from the group consisting of N, O, S and P, and the rest being carbon. When the heteroaryl group is a condensed ring, each ring may contain one to three heteroatoms.

[0035] In order to clearly explain the present invention, parts not related to the description are omitted, and the same reference numerals are given to the same or similar components throughout the specification.

[0036] In one example of the present invention, a high-purity asphalt for a carbon raw material is provided, in which the ratio of the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin to the total content of quinoline soluble-toluene insoluble matter as β resin is less than 0.65.

[0037] In the above-mentioned high-purity pitch for carbon raw material, the content of quinoline insoluble matter may be 0.05% or less.

[0038] In the above-mentioned high-purity pitch for carbon raw material, the ash content may be 0.02% or less, and the weight ratio of quinoline soluble-toluene insoluble matter as β resin to quinoline insoluble matter may be 60 to 10,000.

[0039] Among the β resin components, in particular, the tetrahydrofuran soluble-toluene insoluble matter (hard β resin) has been proven to have a better influence on the physical properties of the carbon raw material than the quinoline soluble-tetrahydrofuran insoluble matter (heavy β resin), and the high-purity asphalt with a high hard β resin component ratio in the high-purity asphalt used as the above-mentioned carbon raw material raw material can be obtained by the preparation method of the high-purity asphalt described later.

[0040] The above-mentioned high-purity pitch can be produced by a method for producing a high-purity pitch for a carbon raw material.

[0041] In another example of the present invention, a method for preparing high-purity asphalt for carbon raw material raw materials is provided, and the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials includes: a step of preparing soft asphalt having a softening point of 10°C to 60°C; a step of mixing the above-mentioned soft asphalt and an aromatic insoluble matter coagulation solvent to prepare a mixture; a step of separating a supernatant portion not containing insoluble matter and a precipitate portion containing insoluble matter from the above-mentioned mixture by centrifugation or decanting; and a step of removing the above-mentioned aromatic insoluble matter coagulation solvent from the above-mentioned supernatant portion not containing insoluble matter by distillation to obtain high-purity asphalt.

[0042] In the high-purity asphalt obtained by the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials, the ratio of the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin to the total content of quinoline soluble-toluene insoluble matter as β resin is below 0.65, specifically, it can be 0.50 to 0.55.

[0043] In the obtained high-purity pitch for carbon raw material, the quinoline insoluble matter content can be 0.05% or less.

[0044] In the high-purity pitch obtained as a raw material for carbon raw materials, the ash content can be less than 0.02%, and the weight ratio of quinoline soluble to toluene insoluble matter as β resin to quinoline insoluble matter can be 60 to 10,000.

[0045] By using the above-mentioned method for preparing high-purity asphalt for carbon raw materials, solid particles called quinoline insoluble (QI) are effectively removed from the above-mentioned coal tar raw materials, while the β resin content is increased and the content of quinoline soluble-tetrahydrofuran insoluble matter, which is heavy β resin, is reduced, thereby preparing asphalt for raw materials that can be used to prepare high-quality carbon raw materials.

[0046] Mesophase pitch used as a precursor of carbon fiber or needle coke can be obtained by heat treatment of raw material pitch, but this raw material pitch contains solid particles insoluble in quinoline, called quinoline insoluble matter, and ash.

[0047] Quinoline insolubles having a size of about 0.2 to about 2.0 μm cannot be removed by ultradecantation operating at about 2500 G to 3000 G and may remain in the tar, thereby affecting the physical properties of the produced coke and carbon products.

[0048] They adhere to the surface of the mesophase spheres as carbon precursors to hinder the growth and integration of the mesophase, thereby inhibiting the growth of anisotropic structures. As a result, the coefficient of thermal expansion (CTE) of the prepared needle coke increases, or adversely affects radioactivity, strength and elastic modulus.

[0049] Therefore, in order to prepare needle coke or carbon raw material products such as carbon fiber, it is necessary to minimize the content of quinoline insoluble matter other than ash components in coal tar-based raw materials such as coal tar or coal tar pitch.

[0050] The β resin component is a substance that assists the generation and growth of the mesophase of the carbonization precursor. The higher the content of the β resin component is, the better the generation and growth of the mesophase will be.

[0051] Generally, the weight ratio of the beta resin to the quinoline insoluble matter in the soft asphalt that has not been pretreated is 5 or less at most.

[0052] The weight ratio of β-resin to quinoline insolubles in the obtained asphalt can be increased by recovering more β-resin or removing quinoline insolubles. In this case, a asphalt that is conducive to the formation and growth of the intermediate phase can be obtained.

[0053] However, if the amount of recovered β resin is large, the amount of quinoline soluble-tetrahydrofuran insoluble matter recovered as heavy β resin is also large, and the quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin has an adverse effect on the physical properties of the carbon raw material.

[0054] Therefore, when preparing pitch, if the weight ratio of beta resin to quinoline insoluble matter is increased and the quinoline soluble-tetrahydrofuran insoluble matter as heavy beta resin is reduced, this pitch can become a raw material for preparing high-quality carbon raw materials.

[0055] By the above-mentioned method for preparing high-purity pitch for carbon raw material raw material, although the quinoline insoluble content can be removed as much as possible and the β resin component can be recovered as much as possible, the recovery rate of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin can be reduced. In addition, the amount of pitch recovered by the above-mentioned method can be recovered by more than 80 weight percent relative to the raw material pitch.

[0056] As a result, the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials can obtain high-purity asphalt while minimizing the quinoline insoluble content, increasing the content of β resin component, and reducing the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin.

[0057] The above-mentioned method for preparing high-purity pitch for carbon raw material raw material uses soft pitch with a softening point between 10°C and 60°C as raw material.

[0058] Soft asphalt is asphalt with a lower softening point. Soft asphalt with a softening point of 10°C to 60°C can be obtained by distilling tar or carbon black oil, or by mixing creosote oil with a binder asphalt with a softening point of 60°C to 150°C.

[0059] Therefore, the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials may also include the following steps: distilling coal tar or carbon black oil to obtain soft asphalt with a softening point of 10°C to 60°C, or mixing creosote oil with a binder asphalt with a softening point of 60°C to 150°C to prepare soft asphalt with a softening point of 10°C to 60°C.

[0060] The aromatic insoluble matter coagulating solvent is mixed with the soft asphalt having a softening point of 10° C. to 60° C. prepared as described above.

[0061] The aromatic insoluble matter condensing solvent is a solvent suitable for condensing the insoluble matter.

[0062] In addition to the above-mentioned aromatic insoluble matter condensing solvent, the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials does not use additional solvent for dissolving impurities, so it does not require the distillation and recovery process of the solvent, thereby saving energy consumption.

[0063] Specifically, the above-mentioned aromatic insoluble matter condensation solvent can be a mixed solvent containing more than 90 weight percent of substituted or unsubstituted aromatic compounds formed by a ring or a combination of more than one of them, and the above-mentioned aromatic compound is substituted in the case that at least one hydrogen atom of the above-mentioned compound is substituted by a substituent selected from the group consisting of C1-C4 alkyl, halogen atoms, -SH, -NH2, -OH and combinations thereof, and two or more of the above-mentioned substituents are fused to form a condensed ring.

[0064] For example, the aromatic insoluble matter condensing solvent may be a solvent comprising one selected from the group consisting of phenol oil, coke oven light oil and a combination thereof, wherein the phenol oil and coke oven light oil are produced in the distillation process of benzene, toluene, xylene, phenol, aniline, thiophenol, chlorobenzene, fluorobenzene and coal tar.

[0065] The above-mentioned method for preparing high-purity pitch for carbon raw material raw materials relatively reduces the usage of the above-mentioned aromatic insoluble matter condensation solvent, thereby improving the processing efficiency of the decanter or centrifuge.

[0066] Since the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials pre-prepare soft asphalt with a softening point of 10°C to 60°C as raw material, it can not only reduce the use of aromatic insoluble matter condensation solvent, but also obtain the required high-purity asphalt.

[0067] Specifically, in the method for preparing the high-purity pitch for the raw material of the carbon raw material, 35 to 150 parts by weight of the aromatic insoluble coagulation solvent is mixed with 100 parts by weight of the soft pitch. If the aromatic insoluble coagulation solvent is used in an amount less than the above range, the coagulation force of the insolubles is reduced, and the desired level of insoluble removal effect cannot be achieved. If the aromatic insoluble coagulation solvent is used in an excessive amount greater than the above range, the processing efficiency of the decanter or centrifuge can be reduced as described above.

[0068] In the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials, the steps of mixing the above-mentioned soft asphalt and the above-mentioned aromatic insoluble matter condensation solvent at a temperature of 40°C to 110°C and separating the above-mentioned mixture by centrifugation or decantation are implemented.

[0069] When mixing the above-mentioned soft asphalt and the above-mentioned aromatic insoluble matter condensing solvent, the higher the temperature, the lower the viscosity of the solution, and thus the better the effect to be achieved. For example, the mixture of the above-mentioned soft asphalt and the above-mentioned aromatic insoluble matter condensing solvent can present a viscosity below 60cP at a temperature of 70°C, specifically, a viscosity of about 1cP to 60cP.

[0070] The above-mentioned weight ratio can be mixed so that the above-mentioned mixture has a viscosity within the above-mentioned range. If the viscosity has the above-mentioned range, there is an advantage that the supernatant and the precipitate can be easily separated during centrifugal separation.

[0071] The mixing time of the raw material of the soft asphalt and the aromatic insoluble coagulation solvent is not particularly limited as long as they can be uniformly mixed, and can be appropriately adjusted according to the mixing efficiency.

[0072] The supernatant obtained by centrifugation or washing is taken as the uniformly mixed mixture solution, thereby removing insoluble matter.

[0073] When the centrifugal separation or decantation method is performed, the higher the temperature, the better, provided that the aromatic insoluble matter condensation solvent does not evaporate. For example, the method can be performed at a temperature ranging from about 40°C to about 110°C.

[0074] When the centrifugal separation method is performed, the centrifugal force may be about 1500 G to about 10000 G, specifically, about 2500 to about 7000 G. The higher the value of the centrifugal force (G-force), the higher the removal rate of insoluble matter or the recovery rate of asphalt and the recovery rate of β resin.

[0075] The supernatant of the separated liquid phase can be distilled under reduced pressure at a maximum temperature of about 280°C or less, specifically, at a temperature of about 40°C to 250°C to remove the aromatic insoluble coagulation solvent, thereby obtaining a high-purity asphalt from which the quinoline insolubles have been removed. On the other hand, the solvent of the supernatant and the precipitate can be recovered and recycled by distillation, so that the aromatic insoluble coagulation solvent can be reused in a continuous process.

[0076] As described above, the above-mentioned method for preparing high-purity pitch for carbon raw materials has an excellent effect of removing quinoline insolubles. For example, in one example, the final pitch obtained by the above-mentioned high-efficiency method for preparing high-purity pitch for carbon raw materials can remove at least 90 weight percent or more or 95 weight percent of quinoline insolubles contained in the coal tar raw material.

[0077] In the above-mentioned method for preparing high-purity asphalt for carbon raw materials, asphalt with a quinoline insoluble content of less than about 0.05 weight percent can be obtained, and the process conditions of the above-mentioned method for preparing high-purity asphalt for carbon raw materials can also be adjusted together to obtain asphalt with a content of less than about 0.01 weight percent.

[0078] As such, a pitch having an insoluble matter content of less than about 0.05 weight percent contains almost no insoluble matter that becomes a physical defect, and thus there is no factor inhibiting the growth of anisotropic structure, thereby having a good effect on the physical properties of the carbon product to be prepared, for example, needle coke or carbon fiber.

[0079] Furthermore, in the above-mentioned method for preparing high-purity asphalt for carbon raw material raw materials, the recovered amount is at least 80 weight percent or more and 98 weight percent or less relative to the raw material, which is beneficial to economy, and the ratio of the content of quinoline soluble-tetrahydrofuran insoluble matter as heavy β resin to the total content of quinoline soluble-toluene insoluble matter as β resin is below 0.65, which is beneficial to the formation of intermediate phase asphalt.

[0080] Using the raw material pitch obtained by the above-mentioned high-efficiency method for preparing high-purity pitch for carbon raw materials, needle coke for artificial graphite with excellent organizational arrangement and low coefficient of thermal expansion (CTE) and carbon fiber with good radioactivity, high elasticity and high strength can be prepared.

[0081] Figure 1 A block diagram showing the steps of a method for efficiently preparing high-purity pitch for carbon raw material feedstock according to an embodiment of the present invention.

[0082] based on Figure 1 , a method for preparing asphalt from which quinoline insolubles of coal have been removed is specifically described as follows. An aromatic insoluble coagulant is added to a soft asphalt having a softening point of 10°C to 60°C and mixed. The mixture is separated into a supernatant containing no insolubles and a precipitate by centrifugal separation, and the aromatic insoluble coagulant is removed from the supernatant obtained after separation by vacuum distillation at a temperature below 280°C, thereby obtaining a high-purity asphalt for raw materials of high-quality carbon raw materials that does not substantially contain quinoline insolubles. On the other hand, the aromatic insoluble coagulant of the supernatant and the precipitate is recovered and recycled by distillation, so that the aromatic insoluble coagulant can be reused.

[0083] The following are specific embodiments of the present invention. However, the embodiments described below are only used to specifically illustrate or describe the present invention, and the present invention is not limited thereto.

[0084] Example

[0085] <Example 1>

[0086] Coal tar containing 3.1 weight percent (wt%) of quinoline insoluble matter was distilled at 240° C. under 30 torr to remove the oil component, thereby preparing soft pitch having a softening point of 35° C.

[0087] After mixing 50 parts by weight of xylene solvent with 100 parts by weight of the soft asphalt, the mixture was stirred by a mechanical stirrer at 60° C. The solution was separated into a supernatant and a precipitate by a centrifugal separator with a centrifugal force of 3000 G at 60° C., and the xylene solvent in the supernatant was removed by distillation.

[0088] Relative to the raw soft asphalt, the recovery rate of high-purity asphalt obtained is 89 weight percent, the quinoline insoluble matter in the high-purity asphalt is 0.002 weight percent, the total ash content is 0.001%, the β-resin content is 7.8 weight percent, the weight ratio of total β-resin to quinoline insoluble matter is 3900, and the weight ratio of heavy β-resin to total β-resin is 0.54.

[0089] <Example 2>

[0090] Creosote oil was mixed into a binder asphalt having a softening point of 85°C and containing 4.1 weight percent of quinoline insoluble matter to prepare a soft asphalt having a softening point of 40°C.

[0091] After mixing 80 parts by weight of xylene solvent with 100 parts by weight of the above-mentioned soft asphalt, the mixture was stirred by a mechanical stirrer at a temperature of 80° C. The above-mentioned solution was separated into a supernatant and a precipitate by a centrifugal separator with a centrifugal force of 4000G at a temperature of 80° C., and the xylene solvent in the supernatant was removed by distillation.

[0092] Relative to the raw soft asphalt, the recovery rate of high-purity asphalt obtained is 84 weight percent, the quinoline insoluble matter in the high-purity asphalt is 0.007 weight percent, the total ash content is 0.003%, the β-resin content is 7.4 weight percent, the weight ratio of total β-resin to quinoline insoluble matter is 1057, and the weight ratio of heavy β-resin to total β-resin is 0.485.

[0093] <Comparative Example 1>

[0094] In the same soft asphalt used in Example 1, 60 parts by weight of petroleum kerosene having an initial boiling point of 190° C. was added to 100 parts by weight of coal tar pitch, and the mixture was stirred at 120° C. using a mechanical stirrer. The solution was allowed to settle at 200° C., and the upper 70% portion was recovered by volume, and the kerosene solvent was removed by distillation to obtain a high-purity asphalt.

[0095] At this time, relative to the raw soft asphalt, the recovery rate of high-purity asphalt is 65 weight percent, the quinoline insoluble matter in the high-purity asphalt is 0.082 weight percent, the total ash content is 0.018%, the β-resin content is 2.2 weight percent, the weight ratio of total β-resin to quinoline insoluble matter is 27, and the weight ratio of heavy β-resin to total β-resin is 0.665.

[0096] It is found that the recovery rate of the high-purity asphalt and the recovery rate of the β resin prepared by the static precipitation method using an aliphatic solvent are lower than those in the above-mentioned Example 1, and in particular, the heavy β resin component is higher in the total β resin component.

[0097] <Comparative Example 2>

[0098] In the binder asphalt with a softening point of 85° C. used in Example 2, 80 parts by weight of toluene solvent was added to 100 parts by weight of the asphalt, and the mixture was stirred by a mechanical stirrer at 80° C. The solution was separated into a supernatant and a precipitate by a centrifugal separator with a centrifugal force of 4000 G at 80° C., and the xylene solvent in the supernatant was removed by distillation.

[0099] Relative to the raw soft asphalt, the recovery rate of high-purity asphalt obtained is 83 weight percent, the quinoline insoluble matter in the high-purity asphalt is 0.165 weight percent, the total ash content is 0.030%, the β-resin content is 7.8 weight percent, the weight ratio of total β-resin to quinoline insoluble matter is 47, and the weight ratio of heavy β-resin to total β-resin is 0.690.

[0100] Comparative Example 2 is a case where a high-purity asphalt with a softening point of more than 60°C is used as a raw material. Since the high-purity asphalt obtained contains a lot of quinoline insolubles, it is not actually suitable for high-quality high-purity asphalt used as a raw material for carbon raw materials. Moreover, compared with Example 2, the β resin component of the prepared high-purity asphalt contains more heavy substances, so it is not preferred.

[0101] A number of preferred embodiments of the present invention have been described in detail above, but the scope of protection of the present invention is not limited thereto. Various modifications and improvements made by ordinary technicians in the technical field of the present invention using the basic concepts of the present invention as defined in the following scope of protection of the present invention also fall within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity asphalt, characterized in that: include: Step (a), preparing soft asphalt having a softening point of 10°C to 60°C; Step (b), mixing the soft asphalt with an aromatic insoluble coagulation solvent to prepare a mixture; and Step (c), separating the supernatant portion not containing insoluble matter and the precipitate portion containing insoluble matter from the mixture by centrifugation or decantation; Step (d), distilling the supernatant under reduced pressure at a temperature of 40° C. to 250° C. to remove the aromatic insoluble matter condensation solvent, The mixture of step (b) is obtained by mixing 100 parts by weight of the soft asphalt with 35 to 150 parts by weight of the aromatic insoluble coagulation solvent having coagulation properties on β-resin and quinoline insolubles, wherein the aromatic insoluble coagulation solvent is xylene solvent. The ratio of heavy beta resin content to total beta resin content is below 0.

65. The weight ratio of the quinoline soluble-toluene insoluble matter of the β resin to the quinoline insoluble matter is 60 to 10,000, The soft asphalt in step (a) is prepared by distilling coal tar or carbon black oil to obtain a soft asphalt with a softening point of 10°C to 60°C, or by mixing creosote oil with a binder asphalt with a softening point of 60°C to 150°C to prepare a soft asphalt with a softening point of 10°C to 60°C. The steps of mixing the soft asphalt and the aromatic insoluble matter coagulation solvent at a temperature of 40° C. to 110° C. and separating the mixture by centrifugal separation or decantation are performed.

2. The method for preparing high-purity asphalt according to claim 1, characterized in that: Also includes: In step (b), the mixture is stirred using a mechanical stirrer. In the centrifugal separation method of step (c), the mixture is separated using a centrifugal separator with a centrifugal force set to 1500G to 10000G, and the decantation method uses a decanter.

3. The method for preparing high-purity asphalt according to claim 1, characterized in that: The ash content is 0.02% or less.

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