Method for preparing petroleum-based pitch having high softening point

Abstract

The present disclosure relates to a method for preparing petroleum-based pitch having a high softening point, and more particularly, to a method for preparing petroleum-based pitch having a high softening point, the method including performing an oxidation heat treatment process on petroleum-based residue by using an oxidation heat treatment device including an oxidation reactor and performing a vacuum heat treatment process on the petroleum-based residue that is oxidized and heat-treated. Here, a ratio of a height and a diameter of the oxidation reactor is about 0.5 to about 2, and a content of quinoline insoluble (QI) in the petroleum-based pitch having the high softening point is about 0.001 weight% to about 0.5 weight% based on a total weight of the petroleum-based pitch having the high softening point.

Description

BACKGROUND

[0001] The present disclosure herein relates to a method for preparing petroleum-based pitch having a high softening point, and more particularly, to a method for preparing highly pure petroleum-based pitch having a high softening point, which capable of restricting quinoline insoluble (QI) from being generated in an oxidation heat treatment process.

[0002] Pitch having a high softening point is used as a raw material or a precursor material of a graphite material or various carbon materials such as a carbon fiber, an activated carbon, and a negative electrode material of a secondary battery. A generally well-known method for preparing the pitch having the high softening point prepares the pitch having the high softening point through an oxidation process and a heat treatment process by using a coal-based or petroleum-based material as a raw material.

[0003] When the pitch having the high softening point is used as a raw material of the negative electrode material of the secondary battery, as a content of quinoline insoluble, inorganic impurities such as metal, or heteroatoms such as nitrogen or sulfur in the petroleum-based pitch having the high softening point is decreased, a capacity, a lifespan feature, and an output feature of the battery may improve. Since a petroleum-based material contains almost no quinoline insoluble, the pitch having the high softening point prepared by using the petroleum-based material as a raw material contains a less amount of quinoline insoluble than the pitch having the high softening point prepared by using the coal-based material as a raw material, but a small amount of quinoline insoluble is produced in the preparing process. The quinoline insoluble produced in the preparing process causes degradation in performance of the secondary battery when the pitch having the high softening point is used as a raw material of the negative electrode material.

[0004] A typical technology of preparing the pitch having the high softening point by using the coal-based or petroleum-based material may not economically prepare the pitch having the high softening point because a content of the quinoline insoluble in the prepared pitch having the high softening point is high, and dangerous materials such as a boron compound, hydrofluoric acid, and a peroxide compound is used for preparing the pitch having the high softening point. Particularly, when the pitch having the high softening point is prepared by using the petroleum-based material, a method for restricting the quinoline insoluble from being generated in the preparing process is not suggested. US 5 387 333 A relates to a process for producing optically isotropic pitch. US 5 446 005 A relates to pitch-based carbon fiber. CN 102 453 491 A relates to a preparation method for controlling the softening point of an oxidized asphalt product. CN 1 212 990 A relates to a method for producing high-viscosity asphalt.SUMMARY

[0005] The present disclosure provides a method for economically preparing pitch having a high softening point.

[0006] The present disclosure also provides a method for preparing high quality pitch having a high softening point, in which a content of quinoline insoluble (QI) is remarkably decreased.

[0007] An embodiment of the inventive concept provides a method for preparing petroleum-based pitch having a high softening point, the method including: performing an oxidation heat treatment process on petroleum-based residue by using an oxidation heat treatment device including an oxidation reactor; and performing a vacuum heat treatment process on the petroleum-based residue that is oxidized and heat-treated. Here, a ratio of a height and a diameter of the oxidation reactor is about 0.5 to about 2, and a content of quinoline insoluble (QI) in the petroleum-based pitch having the high softening point is about 0.001 weight% to about 0.5 weight% based on a total weight of the petroleum-based pitch having the high softening point. According to the presently claimed invention, performing the oxidation heat treatment process comprises: supplying an oxidizing gas to the oxidation reactor by using a gas supply part; sensing and adjusting a temperature of a lower portion of the oxidation reactor by using a lower temperature sensor; sensing and adjusting a temperature of an upper portion of the oxidation reactor by using an upper temperature sensor; and independently heating the upper and lower portions of the oxidation reactor by using a heating part, such that the temperature of the upper portion is maintained less than the temperature of the lower portion, wherein a flow rate of the oxidizing gas is 0.01 L / min to 1 L / min based on 1 kg of the petroleum-based residue, the temperature of the upper portion is maintained in a range from 250°C to 370°C, the temperature of the lower portion is maintained in a range from 250°C to 400°C, a process time of the oxidation heat treatment process is 1 hour to 20 hours, wherein a pressure of the vacuum heat treatment process is 1 torr to 300 torr (0.13 kPa to 40.0 kPa), a heat treatment temperature of the vacuum heat treatment process is 300°C to 430°C, a process time of the vacuum heat treatment process is 1 hour to 20 hours, wherein the petroleum-based residue is pyrolysis fuel oil.BRIEF DESCRIPTION OF THE FIGURES

[0008] The accompanying drawings are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the inventive concept and, together with the description, serve to explain principles of the inventive concept. In the drawings: FIG. 1 is a flowchart for explaining a method for preparing petroleum-based pitch having a high softening point according to an embodiment of the inventive concept; FIG. 2 is a schematic view for explaining an oxidation heat treatment device according to an embodiment of the inventive concept; FIG. 3 is a photograph of a negative electrode active material prepared by using petroleum-based pitch having a high softening point prepared according to embodiments of the inventive concept; and FIG. 4 is a schematic process chart for explaining the method for preparing the petroleum-based pitch having a high softening point according to an embodiment of the inventive concept. DETAILED DESCRIPTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so as to sufficiently understand constitutions and effects of the present invention. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Further, the present invention is only defined by scopes of claims.

[0010] In this specification, it will also be understood that when another component is referred to as being 'on' one component, it can be directly on the one component, or an intervening third component may also be present. Also, in the figures, the dimensions of components are exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout.

[0011] Also, though terms like a first, a second, and a third are used to describe various regions and layers in various embodiments of the inventive concept, the regions and the layers are not limited to these terms. These terms are only used to distinguish one component from another component. An embodiment described and exemplified herein includes a complementary embodiment thereof.

[0012] In the following description, the technical terms are used only for explaining a specific exemplary embodiment while not limiting the present disclosure. In the specification, the terms of a singular form may include plural forms unless referred to the contrary. Also, the meaning of "include," "comprise," "including," or "comprising," specifies a property, a region, a fixed number, a step, a process, an element and / or a component but does not exclude other properties, regions, fixed numbers, steps, processes, elements and / or components.

[0013] FIG. 1 is a flowchart for explaining a method for preparing petroleum-based pitch having a high softening point according to an embodiment of the inventive concept.

[0014] FIG. 2 is a schematic view for explaining an oxidation heat treatment device according to an embodiment of the inventive concept.

[0015] FIG. 4 is a schematic process chart for explaining the method for preparing the petroleum-based pitch having a high softening point according to an embodiment of the inventive concept.

[0016] Referring to FIGS. 1, 2, and 4, the method for preparing the petroleum-based pitch having a high softening point according to an embodiment of the inventive concept may include: a process S1 of performing an oxidation heat treatment process on petroleum-based residue by using an oxidation heat treatment device 1 including an oxidation reactor 100; and a process S2 of performing a vacuum heat treatment process on the petroleum-based residue that is oxidized and heat-treated.

[0017] The petroleum-based residue may have a higher carbonization yield and a higher aromatic ratio than those of light oil. Thus, the petroleum-based residue may be suitable as a source material of a carbon material. The petroleum-based residue may have a chemical and physical property that is different depending on a process condition. The petroleum-based residue may include a reactive material. For example, the reactive material in the petroleum-based residue may include at least one of indene, indene derivatives, styrene, and styrene derivatives.

[0018] According to the presently claimed invention, the petroleum-based residue is pyrolysis fuel oil (PFO).

[0019] The method for preparing the petroleum-based pitch having the high softening point may further include a process of performing a pretreatment process on the petroleum-based residue and a process of injecting the petroleum-based residue that has undergone the pretreatment process to the oxidation reactor before the oxidation heat treatment process is performed. The petroleum-based residue may be used as a raw material for preparing the pitch having the high softening point by the pretreatment process. More specifically, light oil in the petroleum-based residue may be removed by the pretreatment process. In general, a property of the pitch having the high softening point may be easily changed according to various properties of the raw material used for preparing the pitch having the high softening point. According to an embodiment of the inventive concept, as the light oil in the petroleum-based residue is removed by the pretreatment process, the property of the pitch having the high softening point may be relatively uniformly maintained. Thus, a following oxidation heat treatment process or a following vacuum heat treatment process may be easily performed. Also, as reactive materials such as indene, indene derivatives, styrene, and styrene derivatives contained in the light oil are removed by the pretreatment process, an amount of quinoline insoluble (QI) produced in the oxidation heat treatment reaction may be decreased. In this specification, the quinoline insoluble (QI) may represent solid particles that are insoluble in a quinoline solvent. In general, when the pitch having the high softening point is prepared from the petroleum-based residue, the quinoline insoluble (QI) may be produced in a preparing process. Unlike an embodiment of the inventive concept, when the pitch having the high softening point, which has a high content of the quinoline insoluble (QI), is used as a raw material of a negative electrode material of a secondary battery, the secondary battery may be degraded in performance.

[0020] The oxidation heat treatment device 1 may include an oxidation reactor 100, an oxidizing gas supply part 110, an inert gas supply part 120, a gas supply part 130, a stirring part 140, an electric heater 150, first to third flow rate measuring parts 161, 162, and 163, first to third flow rate regulating valves 171, 172, and 173, a circulation pump 180, a heating jacket 190, an upper temperature sensor 200, a central temperature sensor 210, and a lower temperature sensor 220.

[0021] The oxidizing gas supply part 110 may supply an oxidizing gas to the gas supply part 130. For example, the oxidizing gas may include at least one of air, oxygen, and ozone. For example, air in the atmosphere may be directly used as the oxidizing gas.

[0022] The inert gas supply part 120 may supply an inert gas to the gas supply part 130. For example, the inert gas may include at least one of nitrogen and argon.

[0023] The gas supply part 130 may be disposed between the oxidizing gas supply part 110 and the oxidation reactor 100 and between the inert gas supply part 120 and the oxidation reactor 100. The oxidizing gas or the inert gas may be charged to the oxidation reactor 100 through the gas supply part 130. In an embodiment, only the oxidizing gas may be charged to the oxidation reactor 100. In another embodiment, the oxidizing gas and the inert gas may be charged to the oxidation reactor 100. In this case, the oxidizing gas may be diluted with the inert gas. For example, a concentration of oxygen may be adjusted by diluting the oxygen with nitrogen.

[0024] The oxidizing gas has a flow rate of about 0.01 L / min to about 1 L / min based on about 1 kg of the petroleum-based residue. When the flow rate of the oxidizing gas exceeds about 1 L / min based on about 1 kg of the petroleum-based residue, a concentration of oxygen reacting with vaporized aromatic hydrocarbon may be increased, and an amount of the quinoline insoluble (QI) formed on an inner wall of the oxidation reactor 100 may be increased.

[0025] The first flow rate measuring part 161 may be disposed between the oxidizing gas supply part 110 and the gas supply part 130, and the second flow rate measuring part 162 may be disposed between the inert gas supply part 120 and the gas supply part 130. The first flow rate regulating valve 171 may be disposed between the first and second flow rate measuring parts 161 and 162 and the gas supply part 130. A flow rate of the oxidizing gas supply part 110 may be measured by the first flow rate measuring part 161, and a flow rate of the inert gas supply part 120 may be measured by the second flow rate measuring part 162. A flow rate of the oxidizing gas or the inert gas charged to the gas supply part 130 may be regulated by the first flow rate regulating valve 171.

[0026] The oxidation reactor 100 may be a reactor in which an oxidation heat treatment process is performed on the petroleum-based residue. The oxidation heat treatment process may be performed by using the oxidation heat treatment device 1 including the oxidation reactor 100. The oxidation heat treatment process may include a process of heating the oxidizing gas and the petroleum-based residue that are reactants of the oxidation heat treatment process.

[0027] For example, a temperature of the reactant of the oxidation heat treatment process is in a range from about 250°C to about 400°C. In this specification, the temperature of the reactant in the oxidation heat treatment process may represent a temperature of a portion filled with the reactant of the oxidation heat treatment process, for example, a temperature measured by the lower temperature sensor 220. However, when the temperature of the reactant in the oxidation heat treatment process is less than about 250°C, since a molecular weight of the petroleum-based residue is not sufficiently increased, a yield of the pitch having the high softening point that is an end product may be reduced. Also, when the temperature of the reactant in the oxidation heat treatment process is greater than about 400°C, as a content of the quinoline insoluble in the reactant of the oxidation heat treatment process is rapidly increased, a coking phenomenon may occur.

[0028] For example, the oxidation heat treatment process has a process time in a range from about 1 hour to about 20 hours. When the process time of the oxidation heat treatment process is less than about 1 hour, an oxidation reaction may not be sufficiently generated. Also, when the process time of the oxidation heat treatment process is greater than about 20 hours, an excessive polymerization reaction may be caused, and a property of the pitch having the high softening point may be varied. Particularly, when the oxidation reaction is excessively performed, a content of oxygen of the pitch having the high softening point may be increased. Thus, when the pitch having the high softening point is used as the raw material of the negative electrode material of the secondary battery, a performance of the secondary battery may be degraded. Also, when an excessive polymerization reaction of aromatic compounds is performed as the petroleum-based residue is heat-treated under a high temperature condition or an oxidation reaction condition, the petroleum-based residue may be converted into an insoluble material.

[0029] For example, a ratio (L / D) of a height L and a diameter D of the oxidation reactor 100 is in a range from about 0.5 to about 2. When the oxidation heat treatment reaction is performed on the petroleum-based residue, petroleum oil may be vaporized and exposed to the oxidizing gas. When the oxidation heat treatment reaction is performed by mixing the petroleum-based residue with the oxidizing gas, the aromatic hydrocarbon volatilized at a high temperature may react with the oxidizing gas, and the quinoline insoluble (QI) may be adsorbed onto the inner wall of the oxidation reactor 100. For example, an amount of the quinoline insoluble (QI) adsorbed to the inner wall of the oxidation reactor 100 may be greater than that of the quinoline insoluble (QI) produced from the inside of the reactant of the oxidation heat treatment process.

[0030] According to an embodiment of the inventive concept, as the ratio (L / D) of the height L and the diameter D of the oxidation reactor 100 is in the range from about 0.5 to about 2, an amount of impurities in the petroleum-based pitch having the high softening point may be decreased, and, at the same time, the oxidation heat treatment reaction may be effectively performed. However, when the ratio (L / D) of the height L and the diameter D of the oxidation reactor 100 is greater than about 2, an inner area of the reactor in which the quinoline insoluble is formed may be increased, and resultantly, an amount of impurities in the petroleum-based pitch having the high softening point may be increased. Also, when the ratio (L / D) of the height L and the diameterD of the oxidation reactor 100 is less than about 0.5, heat transfer in the reactor according to a temperature gradient may be difficult as the diameter D of the oxidation reactor is increased, and accordingly, an efficiency of the oxidation reaction may be degraded.

[0031] The upper temperature sensor 200, the central temperature sensor 210, and the lower temperature sensor 220 may be disposed in the oxidation reactor 100. The upper temperature sensor 200 may be disposed at an upper portion in the oxidation reactor 100. The lower temperature sensor 220 may be disposed at a lower portion in the oxidation reactor 100. The central temperature sensor 210 may be disposed between the upper temperature sensor 200 and the lower temperature sensor 220.

[0032] The central temperature sensor 210 may adjust a temperature of a central portion in the oxidation reactor 100. The lower temperature sensor 220 adjusts a temperature of the lower portion in the oxidation reactor 100. The upper temperature sensor 200 adjusts a temperature of the upper portion in the oxidation reactor 100. For example, the temperature of the upper portion in the oxidation reactor 100 is maintained in a range from about 250°C to about 370°C or in a range from about 280°C to about 360°C. In this specification, the upper portion in the oxidation reactor may represent a portion in which the reactant of the oxidation heat treatment process is not filled. To this end, the oxidation heat treatment device 1 further includes a heating part for independently heating the upper portion and the lower portion of the oxidation reactor 100. When the temperature of the upper portion in the oxidation reactor 100 is greater than about 370°C, a speed of the polymerization reaction generated by the volatilized aromatic hydrocarbon and the oxidizing gas may be rapidly increased. Thus, the amount of the quinoline insoluble (QI) adsorbed in the oxidation reactor 100 may be rapidly increased. Furthermore, the temperature of the upper portion in the oxidation reactor is less than that of the reactant of the oxidation heat treatment process.

[0033] In general, a catalyst may be used under a high pressure condition to increase the softening point of the pitch having the high softening point that is the end product, and the oxidizing gas and a peroxide-based compound. However, when the catalyst is used under the high pressure condition, since an expensive high pressure vessel is necessary, and a separate process of removing the catalyst is necessary, costs of producing the pitch having the high softening point may be increased. Also, when the peroxide-based compound is additionally mixed to the oxidizing gas, a risk of explosion during the preparing process may exist by high reactivity of the peroxide-based compound, and costs for the peroxide-based compound, dangerous substances management costs, and waste water treatment costs may be increased. Thus, an economic efficiency for preparing a large amount of the pitch having the high softening point may be degraded.

[0034] According to an embodiment of the inventive concept, the molecular weight of the petroleum-based residue may be increased by the oxidation heat treatment process, and the yield of the pitch having the high softening point that is the end product may improve. Particularly, since the high pressure condition may not be required in the oxidation heat treatment process, and the catalyst may not be used, the economical and high quality petroleum-based pitch having the high softening point may be prepared. Furthermore, according to an embodiment of the inventive concept, the peroxide-based compound may not be charged to the oxidation reactor 100 before or while the oxidation heat treatment process is performed. As the peroxide-based compound is not used, the preparing method may be economical, and the risk of explosion during the preparing process may be prevented.

[0035] The stirring part 140 may be disposed in the oxidation reactor 100. The reactants of the oxidation heat treatment process may be smoothly mixed by the stirring part 140.

[0036] As the heating jackets 190 are disposed on an outer wall of the oxidation reactor 100, the heating jackets 190 may cover a portion of the outer wall of the oxidation reactor 100. The heating jackets 190 may perform an insulation, electrical insulation, or warming function of the oxidation reactor 100.

[0037] The circulation pump 180 may be connected to the oxidation reactor 100. For example, the circulation pump 180 may be connected to a lower portion of the oxidation reactor 100. The reactants of the oxidation heat treatment process may be injected to the electric heater 150 by the circulation pump 180. The electric heater 150 may be connected to the circulation pump 180. That is, the circulation pump 180 may be disposed between the oxidation reactor 100 and the electric heater 150. The third flow rate measuring part 163 and the second flow rate regulating valve 172 may be disposed between the circulation pump 180 and the electric heater 150. The third flow rate measuring part 163 may be disposed adjacent to the circulation pump 180, and the second flow rate regulating valve 172 may be disposed adjacent to the electric heater 150. The third flow rate measuring part 163 may measure a flow rate of the reactant of the oxidation heat treatment process, which is injected to the electric heater 150. The second flow rate regulating valve 172 may regulate the flow rate of the reactant of the oxidation heat treatment process, which is injected to the electric heater 150. The electric heater 150 may heat the reactant of the oxidation heat treatment process. The reactant of the oxidation heat treatment process, which is heated by the electric heater 150, may be injected to the oxidation reactor 100 again. For example, the reactant of the oxidation heat treatment process, which is heated by the electric heater 150, may be injected to the upper portion of the oxidation reactor 100. The third flow rate regulating valve 173 may be disposed between the electric heater 150 and the upper portion of the oxidation reactor 100. The flow rate of the reactant of the oxidation heat treatment process, which is injected to the upper portion of the oxidation reactor 100, may be regulated by the third flow rate regulating valve 173.

[0038] The petroleum-based pitch may be prepared from the oxidized and heat-treated petroleum-based residue through the oxidation heat treatment process. Hereinafter, in this specification, the petroleum-based pitch may represent the petroleum-based residue that is oxidized and heat-treated by the oxidation heat treatment process. The vacuum heat treatment process is performed on the petroleum-based residue. The vacuum heat treatment process includes a process of heating the petroleum-based residue under a vacuum condition. The vacuum heat treatment process may be performed in a decompressing heat treatment device.

[0039] In an embodiment of the inventive concept, the vacuum heat treatment process may remove heavy oil of the petroleum-based pitch, increase the softening point, and increase a content of toluene insoluble, thereby increasing a carbonization yield of the pitch. Unlike an embodiment of the inventive concept, when an atmospheric pressure heat treatment process or a pressing heat treatment process is performed on the petroleum-based pitch instead of the vacuum heat treatment process, the heavy oil may be difficult to be removed, and the softening point of the pitch may not be increased.

[0040] For example, the vacuum heat treatment process has a pressure in a range from about 1 torr to about 300 torr (0.13 kPa to 40.0 kPa) from about 1 torr to about 200 torr (0.13 kPa to 26.7 kPa) or from about 1 torr to about 100 torr (0.13 kPa to 13.3 kPa). For example, the vacuum heat treatment process has a heat treatment temperature in a range from about 300°C to about 430°C. When the heat treatment temperature of the vacuum heat treatment process is less than about 300°C, the heavy oil may be difficult to be removed, and as producing of the toluene insoluble is reduced, the high quality pitch having the high softening point may be difficult to be prepared. Also, as the heavy oil in the pitch is not sufficiently removed, there may be a limitation of increasing the softening point of the petroleum-based pitch. When the heat treatment temperature of the vacuum heat treatment process is greater than about 430°C, the coking phenomenon of the petroleum-based pitch may occur to provide coke, or the content of the quinoline insoluble (QI) may be rapidly increased.

[0041] For example, the vacuum heat treatment process has a process time in a range from about 1 hour to about 20 hours or from about 2 hours to about 10 hours. When the process time of the vacuum heat treatment process is less than about 1 hour, the heavy oil may not be sufficiently removed, and thus the preparing of the pitch having the high softening point may be difficult. Also, the toluene insoluble may not be sufficiently produced due to lack of a thermal polymerization reaction time, and a low quality pitch having a high softening point and a low carbonization yield may be prepared. When the process time of the vacuum heat treatment process is greater than about 20 hours, the toluene insoluble may be excessively produced as the polymerization reaction is excessively performed, and costs for operating processes and expenses for preparing a product may be increased as the process time is increased.

[0042] The vacuum heat treatment process may further include a process of mixing an inert gas or steam. The heavy oil of the petroleum-based pitch may be effectively removed in the vacuum heat treatment device by the vacuum heat treatment process. For example, the inert gas may include at least one of nitrogen and argon.

[0043] For example, a flow rate of the inert gas or the steam may be in a range from about 0.01 L / min to about 2.0 L / min based on about 1 kg of the petroleum-based pitch. Unlike an embodiment of the inventive concept, when the oxidizing gas is charged while the vacuum heat treatment process is performed, the quinoline insoluble may be rapidly formed by an oxidation reaction at a high temperature. Thus, according to an embodiment of the inventive concept, the inert gas or the steam may be charged in the vacuum heat treatment process. Particularly, when the inert gas or the steam are heated and charged, the heavy oil may be further effectively removed.

[0044] The method for preparing the petroleum-based pitch having the high softening point according to an embodiment of the inventive concept may further perform the atmospheric pressure heat treatment process on the petroleum-based pitch after the vacuum heat treatment process. The content of the toluene insoluble of the petroleum-based pitch having the high softening point may be increased by the atmospheric pressure heat treatment process. For example, the atmospheric pressure heat treatment process may have a heat treatment temperature in a range from about 300°C to about 430°C. When the heat treatment temperature of the atmospheric pressure heat treatment process is less than about 300°C, the heavy oil toluene insoluble may not be produced. When the heat treatment temperature of the atmospheric pressure heat treatment process is greater than about 430°C, the coking phenomenon of the petroleum-based pitch may occur to provide coke, or the content of the quinoline insoluble may be rapidly increased.

[0045] For example, the atmospheric pressure heat treatment process may have a process time in a range from about 30 minutes to about 20 hours. When the process time of the atmospheric pressure heat treatment process is less than about 30 minutes, the toluene insoluble may not be sufficiently produced. When the process time of the atmospheric pressure heat treatment process is greater than about 20 hours, costs for operating processes and expenses for preparing a product may be increased as the process time is increased.

[0046] The petroleum-based pitch having the high softening point, which is prepared by the method for preparing the petroleum-based pitch having the high softening point according to an embodiment of the inventive concept, may have a softening point in a range from about 150°C to about 300°C. For example, a content of the quinoline insoluble (QI) of the petroleum-based pitch having the high softening point may be equal to or less than about 0.5 weight% based on a total weight of the petroleum-based pitch having the high softening point or in a range from about 0.001 weight% to about 0.5 weight%. That is, according to an embodiment of the inventive concept, the petroleum-based pitch having the high softening point may have the high softening point and simultaneously reduce the contend of the quinoline insoluble therein.

[0047] According to an embodiment of the inventive concept, the petroleum-based pitch having the high softening point is prepared through the oxidation heat treatment process and the vacuum heat treatment process by using the petroleum-based residue as a raw material, and the petroleum-based pitch having the high softening point may be used as a raw material of a carbon material or a graphite material and a precursor material of the carbon material or the graphite material. For example, the carbon material or the graphite material may include a carbon fiber, an activated carbon, a negative electrode material of a secondary battery.

[0048] In general, when the petroleum-based pitch having the high softening point is used as the raw material of the negative electrode material of the secondary battery, the secondary battery may be degraded in performance by the quinoline insoluble. That is, as a content of the quinoline insoluble, inorganic impurities such as metal, or heteroatoms such as nitrogen or sulfur in the petroleum-based pitch having the high softening point is decreased, a capacity, a lifespan feature, and an output feature of the battery may improve.

[0049] Since the petroleum-based pitch having the high softening point prepared by the method for preparing the petroleum-based pitch having the high softening point according to an embodiment of the inventive concept has the high softening point and simultaneously has the reduced content of the quinoline insoluble, the performance of the secondary battery may improve by using the petroleum-based pitch having the high softening point as the raw material of the negative electrode material of the secondary battery.

[0050] In an embodiment, the petroleum-based pitch having the high softening point may be used as a binder material or a coating material of the negative electrode material (e.g., a natural graphite negative electrode material or artificial graphite negative electrode material). In another embodiment, a carbonization process may be performed on the petroleum-based pitch having the high softening point to be used as a carbon negative electrode material.

[0051] Also, the petroleum-based pitch having the high softening point prepared by the method according to an embodiment of the inventive concept may be used as a precursor material through a carbonization process and a graphitization process. When the petroleum-based pitch having the high softening point according to an embodiment of the inventive concept is used as a precursor material of a carbon fiber, the prepared carbon fiber may have improved properties such as a tensile strength and a tensile modulus by the high softening point and carbonization yield and the low content of the quinoline insoluble of the petroleum-based pitch having the high softening point.

[0052] Also, the petroleum-based pitch having the high softening point prepared by the method according to an embodiment of the inventive concept may be used as a precursor material of an activated carbon through a carbonization process and an activation process. Since the petroleum-based pitch having the high softening point according to an embodiment of the inventive concept has the high softening point, a high carbonization yield, a high mechanical property, and a low impurity content, the prepared activated carbon may have improved specific surface area and mechanical strength.Embodiment Embodiment 1

[0053] Pyrolysis fuel oil (PFO) is used as the petroleum-based residue, and air is used as the oxidizing gas. The pyrolysis fuel oil (PFO) is injected to the oxidation reactor in which the ratio (L / D) of the height (L) and the diameter (D) is about 1.6. The oxidation heat treatment process is performed by charging air with a flow rate of about 0.5 L / min based on about 1 kg of the pyrolysis fuel oil (PFO). The reactant of the oxidation heat treatment process has a temperature of about 370°C, and the upper portion in the oxidation reactor has a temperature of about 350°C. The oxidation heat treatment process is performed during about 4 hours.

[0054] Thereafter, as the vacuum heat treatment process is performed by decompressing the pressure to a pressure of about 80 torr and during about 10 hours at a temperature of about 400°C, the petroleum-based pitch having the high softening point is prepared. The softening point of the prepared petroleum-based pitch having the high softening point is about 251°C, the content of the quinoline insoluble is about 0.08 weight% based on the total weight of the petroleum-based pitch having the high softening point, and a coking value is about 65 weight%.Embodiment 2

[0055] Pyrolysis fuel oil (PFO) is used as the petroleum-based residue, and air is used as the oxidizing gas. The pyrolysis fuel oil (PFO) is injected to the oxidation reactor in which the ratio (L / D) of the height (L) and the diameter (D) is about 1.6. The oxidation heat treatment process is performed by charging air with a flow rate of about 0.2 L / min based on about 1 kg of the pyrolysis fuel oil (PFO). The reactant of the oxidation heat treatment process has a temperature of about 370°C, and the upper portion in the oxidation reactor has a temperature of about 350°C. The oxidation heat treatment process is performed during about 4 hours.

[0056] Thereafter, as the vacuum heat treatment process is performed by decompressing the pressure to a pressure of about 80 torr and during about 10 hours at a temperature of about 400°C, the petroleum-based pitch having the high softening point is prepared. The softening point of the prepared petroleum-based pitch having the high softening point is about 254°C, the content of the quinoline insoluble is about 0.02 weight% based on the total weight of the petroleum-based pitch having the high softening point, and the coking value is about 64 weight%.Embodiment 3

[0057] Pyrolysis fuel oil (PFO) is used as the petroleum-based residue, and air is used as the oxidizing gas. The pyrolysis fuel oil (PFO) is injected to the oxidation reactor in which the ratio (L / D) of the height (L) and the diameter (D) is about 1.6. The oxidation heat treatment process is performed by charging air with a flow rate of about 0.5 L / min based on about 1 kg of the pyrolysis fuel oil (PFO). The reactant of the oxidation heat treatment process has a temperature of about 370°C, and the upper portion in the oxidation reactor has a temperature of about 360°C. The oxidation heat treatment process is performed during about 4 hours.

[0058] Thereafter, as the vacuum heat treatment process is performed by decompressing the pressure to a pressure of about 80 torr (10.7 kPa) and during about 10 hours at a temperature of about 400°C, the petroleum-based pitch having the high softening point is prepared. The softening point of the prepared petroleum-based pitch having the high softening point is about 254°C, the content of the quinoline insoluble is about 0.24 weight% based on the total weight of the petroleum-based pitch having the high softening point, and the coking value is about 68 weight%.Comparative example 1

[0059] Pyrolysis fuel oil (PFO) is used as the petroleum-based residue, and air is used as the oxidizing gas. The pyrolysis fuel oil (PFO) is injected to the oxidation reactor in which the ratio (L / D) of the height (L) and the diameter (D) is about 2.5. The oxidation heat treatment process is performed by charging air with a flow rate of about 0.5 L / min based on about 1 kg of the pyrolysis fuel oil (PFO). The reactant of the oxidation heat treatment process has a temperature of about 370°C, and the upper portion in the oxidation reactor has a temperature of about 350°C. The oxidation heat treatment process is performed during about 4 hours.

[0060] Thereafter, as the vacuum heat treatment process is performed by decompressing the pressure to a pressure of about 80 torr (10.7 kPa) and during about 10 hours at a temperature of about 400°C, the petroleum-based pitch having the high softening point is prepared. The softening point of the prepared petroleum-based pitch having the high softening point is about 245°C, the content of the quinoline insoluble is about 0.76 weight% based on the total weight of the petroleum-based pitch having the high softening point, and the coking value is about 66 weight%.Comparative example 2

[0061] Pyrolysis fuel oil (PFO) is used as the petroleum-based residue, and air is used as the oxidizing gas. The pyrolysis fuel oil (PFO) is injected to the oxidation reactor in which the ratio (L / D) of the height (L) and the diameter (D) is about 1.6. The oxidation heat treatment process is performed by charging air with a flow rate of about 0.5 L / min based on about 1 kg of the pyrolysis fuel oil (PFO). The reactant of the oxidation heat treatment process has a temperature of about 380°C, and the upper portion in the oxidation reactor has a temperature of about 380°C. The oxidation heat treatment process is performed during about 4 hours.

[0062] Thereafter, as the vacuum heat treatment process is performed by decompressing the pressure to a pressure of about 80 torr (10.7 kPa) and during about 10 hours at a temperature of about 400°C, the petroleum-based pitch having the high softening point is prepared. The softening point of the prepared petroleum-based pitch having the high softening point is about 244°C, the content of the quinoline insoluble is about 1.06 weight% based on the total weight of the petroleum-based pitch having the high softening point, and the coking value is about 64 weight%.Comparative example 3

[0063] Pyrolysis fuel oil (PFO) is used as the petroleum-based residue, and air is used as the oxidizing gas. The pyrolysis fuel oil (PFO) is injected to the oxidation reactor in which the ratio (L / D) of the height (L) and the diameter (D) is about 1.6. The oxidation heat treatment process is performed by charging air with a flow rate of about 1.5 L / min based on about 1 kg of the pyrolysis fuel oil (PFO). The reactant of the oxidation heat treatment process has a temperature of about 370°C, and the upper portion in the oxidation reactor has a temperature of about 360°C. The oxidation heat treatment process is performed during about 4 hours.

[0064] Thereafter, as the vacuum heat treatment process is performed by decompressing the pressure to a pressure of about 80 torr and during about 10 hours at a temperature of about 400°C, the petroleum-based pitch having the high softening point is prepared. The softening point of the prepared petroleum-based pitch having the high softening point is about 248°C, the content of the quinoline insoluble is about 0.93 weight% based on the total weight of the petroleum-based pitch having the high softening point, and the coking value is about 58 weight%.

[0065] The ratio (L / D) of the height (L) and the diameter (D) of the oxidation reactor in the oxidation heat treatment process of the embodiments 1 to 3 and the comparative examples 1 to 3, the temperature of the upper portion in the oxidation reactor, the flow rate of the oxidizing gas, and the properties of the petroleum-based pitch having the high softening point are described in table 1 below. [Table 1]Embodi ment 1Embodi ment 2Embodi ment 3Compara tive example 1Compara tive example 2Compara tive example 3Ratio (L / D) of height (L) and diameter (D) of oxidation reactor1.61.61.62.51.61.6Temperature (°C) of upper portion in oxidation reactor350350360350380360Flow rate (L / min) of oxidizing gas based on 1 kg of petroleum residue0.50.20.50.50.51.5Softening point (°C) of petroleum-based pitch having the high softening point251254254245244248Content (weight%) of QI of petroleum-based pitch having the high softening point0.080.020.240.761.060.93Coking value (weight%) of petroleum-based pitch having the high softening point656468666458

[0066] Referring to the table 1 above, it may be understood that the petroleum-based pitch having the high softening point of the embodiments 1 to 3 has the high softening point of about 200°C, the content of the quinoline insoluble equal to or less than about 0.5 weight%, and the high coking value of about 60% or more.

[0067] Although the comparative example 1 uses the same petroleum-based residue as the embodiment 1, as the ratio (L / D) of the oxidation reactor is increased, an adsorption amount of the quinoline insoluble in the oxidation reactor may be increased, and resultantly, the content of impurities in the petroleum-based pitch having the high softening point may be high.

[0068] Although the comparative example 2 uses the same petroleum-based residue and the same sized oxidation reactor as the embodiment 1, as the upper portion of the oxidation reactor has a high temperature to increase a reaction speed between the aromatic hydrocarbon material and the oxidizing gas, a produced amount of the quinoline insoluble may be increased, and resultantly, the content of impurities in the petroleum-based pitch having the high softening point may be high.

[0069] Although the comparative example 3 uses the same petroleum-based residue and the same sized oxidation reactor as the embodiment 3, as the flow rate of the oxidizing gas charged into the oxidation reactor is increased, the content of the quinoline insoluble produced by the polymerization reaction may be increased as an amount of oxygen reacting when the aromatic hydrocarbon material is volatilized is increased, and resultantly, the content of impurities in the petroleum-based pitch having the high softening point may be high.Experimental example Experimental example 1: Preparation of secondary battery using petroleum-based pitch having the high softening point prepared according to embodiment 1

[0070] The secondary battery is prepared by using the petroleum-based pitch having the high softening point prepared according to the embodiment 1 as the coating material of the negative electrode material of the secondary battery.

[0071] Specifically, about 5 g of the petroleum-based pitch having the high softening point prepared according to the embodiment 1 is mixed to about 95 g of spherical natural graphite having a mean diameter of about 15 µm. Thereafter, a surface of the natural graphite is coated with the petroleum-based pitch having the high softening point by using a mechanical stirring device. After the coating is completed, a negative electrode active material is prepared by performing a heat treatment at a temperature of about 1,100°C during about 1 hour.

[0072] A shape of the negative electrode active material prepared by using the petroleum-based pitch having the high softening point prepared according to the embodiment 1 is shown in FIG. 3. It may be checked that the natural graphite is uniformly coated with the petroleum-based pitch having the high softening point.

[0073] A composition for negative electrode slurry is prepared by the negative electrode active material prepared by using the petroleum-based pitch having the high softening point prepared according to the embodiment 1. Specifically, the composition for the negative electrode slurry is prepared by mixing the negative electrode active material, carbon black, carboxymethyl cellulose, and styrene butadiene into water with a weigh ratio of about 91:5:2:2 of negative electrode active material:carbon black: carboxymethyl cellulose:styrene butadiene. The negative electrode for the secondary battery is prepared by coating a copper collector with the composition for the negative electrode slurry and performing drying and rolling for about 1 hour.

[0074] Thereafter, the coin cell type secondary battery is prepared by sequentially laminating a negative electrode, a separator, an electrolyte, and a lithium electrode for the secondary battery. Here, the electrolyte is a solvent in which ethylene carbonate and dimethyl carbonate are mixed with a weight ratio of about 1:1, and 1.0 M LiPF 6 is added.Experimental example 2: Preparation of secondary battery using petroleum-based pitch having the high softening point prepared according to comparative example 2

[0075] The secondary battery is prepared by using the petroleum-based pitch having the high softening point prepared according to the comparative example 2 as the coating material of the negative electrode material of the secondary battery.

[0076] The petroleum-based pitch having the high softening point prepared according to the comparative example 2 is used instead of using the petroleum-based pitch having the high softening point prepared according to the embodiment 1, and except this, the secondary battery is prepared by the substantially same method as the experimental example 1.Experimental example 3: Measurement of charging and discharging capacity and initial efficiency of secondary battery

[0077] A performance of the secondary battery prepared by using the petroleum-based pitches having the high softening point prepared according to the embodiment 1 and comparative example 2 as the coating material of the negative electrode material of the secondary battery is measured.

[0078] Specifically, a charging and discharging capacity and an initial efficiency of each of the prepared secondary batteries are measured according to a condition below. Specifically, charging is performed until about 0.01 V with a constant current of about 0.2 C, and charging is performed until about 0.01 C with a constant voltage of about 0.01 C. Thereafter, discharging is performed until about 1.5 V with a constant current of about 0.2 C. As the above process is repeated by 1st cycle, 50th cycle, and 100th cycle, the initial efficiency and a discharging capacity for each cycle are measured. This result is shown in table 2 below. [Table 2]Initial efficiency (%)Discharging capacity (mAh / g)1 st< cycle50 st< cycle100 st< cycleEmbodiment 190361358356Comparative example 187358343332

[0079] Referring to the table 2 above, when the petroleum-based pitch having the high softening point prepared according to the comparative example 2 is used as the coating material of the natural graphite, the discharging capacity is less, and the initial efficiency is also less than a case when the petroleum-based pitch having the high softening point prepared according to the embodiment 1 is used as the coating material of the natural graphite. This result may be obtained because the petroleum-based pitch having the high softening point prepared according to the comparative example 2 has a higher content of the quinoline insoluble than the petroleum-based pitch having the high softening point prepared according to the embodiment 1.

[0080] The method for preparing the petroleum-based pitch having the high softening point according to the embodiment of the inventive concept may remarkably reduce the quinoline insoluble formed in the preparing process and thus prepare the high quality petroleum-based pitch having the high softening point having a small amount of impurities.

[0081] The method for preparing the petroleum-based pitch having the high softening point according to the embodiment of the inventive concept may not require the separate process of removing the catalyst and may not use the expensive high pressure vessel because the catalyst and the high pressure condition are unnecessary. Also, since the peroxide-based compound is not used, the method may not have the risk of explosion during the preparing process and may not cause environmental pollution. Thus, the high quality petroleum-based pitch having the high softening point may be economically prepared.

[0082] Since the petroleum-based pitch having the high softening point prepared by the method for preparing the petroleum-based pitch having the high softening point according to the embodiment of the inventive concept decreases the content of the quinoline insoluble, the capacity, the lifespan, and the charging and discharging efficiency of the secondary battery to which the petroleum-based pitch having the high softening point is applied may improve.

[0083] Although the exemplary embodiments of the present invention have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art within the scope of the present invention as claimed.

Claims

1. A method for preparing petroleum-based pitch having a high softening point, comprising: performing an oxidation heat treatment process on pyrolysis fuel oil by using an oxidation reactor; and performing a vacuum heat treatment process on the pyrolysis fuel oil that is oxidized and heat-treated, wherein a ratio of a height and a diameter of the oxidation reactor is 0.5 to 2, wherein performing the oxidation heat treatment process comprises: supplying an oxidizing gas to the oxidation reactor by using a gas supply part; sensing and adjusting a temperature of a lower portion of the oxidation reactor by using a lower temperature sensor; sensing and adjusting a temperature of an upper portion of the oxidation reactor by using an upper temperature sensor; and independently heating the upper and lower portions of the oxidation reactor by using a heating part, such that the temperature of the upper portion is maintained less than the temperature of the lower portion, wherein a flow rate of the oxidizing gas is 0.01 L / min to 1 L / min based on 1 kg of the pyrolysis fuel oil, the temperature of the upper portion is maintained in a range from 250°C to 370°C, the temperature of the lower portion is maintained in a range from 250°C to 400°C, a process time of the oxidation heat treatment process is 1 hour to 20 hours, wherein a pressure of the vacuum heat treatment process is 1 torr to 300 torr (0.13 kPa to 40.0 kPa), a heat treatment temperature of the vacuum heat treatment process is 300°C to 430°C, a process time of the vacuum heat treatment process is 1 hour to 20 hours, and a content of quinoline insoluble in the petroleum-based pitch having the high softening point is 0.001 weight% to 0.5 weight% based on a total weight of the petroleum-based pitch having the high softening point.

2. The method of claim 1, wherein the oxidizing gas comprises at least one of air, oxygen, and ozone.

3. The method of claim 1, further comprising: before the performing of the oxidation heat treatment process, performing a pre-treatment process on the pyrolysis fuel oil; and injecting the pyrolysis fuel oil that has undergone the pre-treatment process to the oxidation reactor, wherein light oil in the pyrolysis fuel oil is removed by the pre-treatment process.

4. The method of claim 1, wherein a temperature of a reactant of the oxidation heat treatment process is 250°C to 400°C.

5. The method of claim 1, wherein the vacuum heat treatment process further comprises mixing an inert gas or steam, wherein the inert gas comprises at least one of nitrogen and argon.

6. The method of claim 1, further comprising performing an atmospheric pressure heat treatment process on the pyrolysis fuel oil after the performing of the vacuum heat treatment process, wherein a content of toluene insoluble in the petroleum-based pitch having the high softening point is increased by the atmospheric pressure heat treatment process.

7. The method of claim 6, wherein a heat treatment temperature of the atmospheric pressure heat treatment process is 300°C to 430°C, and a process time of the atmospheric pressure heat treatment process is 30 minutes to 20 hours.

8. The method of claim 1, wherein a softening point of the petroleum-based pitch having the high softening point is 150°C to 300°C.

9. The method of claim 1, wherein a peroxide-based compound is not charged to the oxidation reactor.