Green needle coke as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of petroleum processing, and discloses green needle coke as well as a preparation method and application thereof. The preparation method of the green needle coke comprises the following steps: S1, carrying out chromatographic separation on a heavy aromatic hydrocarbon raw material to obtain an aromatic component; s2, mixing the aromatic component with a polycyclic aromatic hydrocarbon compound to obtain a mixed component; and S3, in an inert atmosphere, carrying out segmented heat treatment on the mixed component to obtain the green needle coke. According to the preparation method disclosed by the invention, the preparation of high-quality green needle coke is realized through collaborative optimization of accurate regulation and control of the raw materials, directional induction of the intermediate phase and segmented heat treatment, and the problems of uneven development of the intermediate phase, insufficient anisotropy, unstable performance and the like in a traditional green needle coke preparation process are solved; a raw material solution which is excellent in performance and controllable in cost is provided for the high-end fields of ultrahigh-power graphite electrodes, lithium ion battery negative electrode materials and the like, and remarkable economic and social benefits are achieved.

Description

Technical Field

[0001] This invention relates to the field of petroleum processing technology, and discloses a needle coke raw coke, its preparation method, and its application. Background Technology

[0002] With increasing global environmental awareness and the booming development of the new energy industry, the traditional petrochemical industry faces enormous pressure to transform and upgrade. Against this backdrop, the high-value-added and high-quality utilization of byproducts from petroleum refining has become an important research direction for improving industrial economic efficiency and achieving sustainable development. Catalytic cracking slurry, a byproduct of petroleum refining, is mainly composed of aliphatic hydrocarbons and mono- and polycyclic aromatic hydrocarbons, and is an important raw material for needle coke production. As a key artificial carbon material, needle coke possesses comprehensive advantages such as a low coefficient of thermal expansion, high electrical conductivity, high mechanical strength, high true density, and good graphitization properties. It is widely used in the manufacture of ultra-high-power graphite electrodes, nuclear graphite, and high-end carbon products in emerging fields such as lithium-ion batteries, sodium-ion battery anode materials, solar cells, and supercapacitors. In recent years, in particular, with the explosive growth of the new energy vehicle market, the demand for high-performance lithium-ion battery anode materials has expanded dramatically. Anode materials prepared using needle coke as a precursor have become mainstream in the market due to their excellent comprehensive performance, further highlighting the strategic value of high-quality needle coke.

[0003] The industrial production of needle coke typically involves three core processes: raw material refining, delayed coking, and high-temperature calcination. Among these, the chemical composition of the raw materials is a crucial factor determining the quality of the final product. However, a fundamental challenge faced by domestic and international companies in their preparation processes lies in the imbalance of raw material components, which severely restricts the formation and development of high-performance anisotropic mesophases. This deficiency manifests in two specific ways: First, excessively high content of light monocyclic and bicyclic aromatic hydrocarbons in the raw materials makes it difficult to form a well-developed, broad-area mesophase, ultimately resulting in coke with poor streamline structure, low crystallinity and orientation, and unsatisfactory coke yield. Second, excessive aliphatic hydrocarbon components in the raw materials, while exhibiting high reactivity, also result in poor thermal stability, an overly vigorous and uncontrollable reaction process, and the early generation of numerous active free radicals. This leads to premature cross-linking and solidification of the system, generating disordered isotropic coke, resulting in products with low orderliness, poor orientation, and mechanical strength insufficient for high-end applications. In addition, the coking reaction temperature and pressure of needle coke are difficult to precisely match the changes in the raw material composition, resulting in overheating or undercooling of the reaction system; excessively high reaction intensity will cause aliphatic hydrocarbons and light aromatic hydrocarbons to rapidly decompose and generate a large number of free radicals, causing the system to cross-link and solidify prematurely, generating a large amount of isotropic coke; while excessively low reaction temperature will cause the condensation reaction of heavy aromatic hydrocarbons to be insufficient, the mesophase to develop incompletely, and the final product to have poor orientation.

[0004] Therefore, developing a method to effectively regulate the composition of raw materials, optimize the reaction path, and stabilize the mesophase growth process to prepare high-quality needle coke with high microcrystalline order, large interlayer stacking height, and good mechanical strength is of great industrial significance for improving the quality of needle coke products and promoting the high-value utilization of petroleum by-products. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a needle-shaped coke, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing needle-shaped char, comprising the following steps: S1. The heavy aromatic hydrocarbon feedstock is separated by chromatography to obtain aromatic components; S2. The aromatic component and the polycyclic aromatic hydrocarbon compound are mixed to obtain a mixed component; the mass of the polycyclic aromatic hydrocarbon compound is 5%-20% of the mass of the mixed component. S3. Under an inert atmosphere, the mixed components are subjected to segmented heat treatment to obtain the needle-shaped coke. The segmented heat treatment includes a first stage heat treatment and a second stage heat treatment. The first stage heat treatment is carried out at a pressure of 0.7MPa-1.5MPa, with the temperature increased to 480℃-540℃ at a rate of 1℃ / min-5℃ / min, and held for 1h-3h. The second stage heat treatment is carried out at a temperature of 450℃-475℃ and a pressure of 0.3MPa-0.5MPa.

[0007] This invention provides a method for preparing needle-shaped raw coke. Through precise raw material control, directional induction of the mesophase, and segmented heat treatment, it achieves the preparation of high-quality needle-shaped raw coke with a highly ordered microcrystalline structure, excellent orientation, high mechanical strength, and low coefficient of thermal expansion. This method solves the core problems of uneven mesophase development and insufficient anisotropy in traditional needle-shaped raw coke preparation processes. It provides a high-performance, cost-effective raw material solution for high-end fields such as ultra-high-power graphite electrodes and lithium-ion battery anode materials, demonstrating significant economic and social benefits. Specifically, this invention adds polycyclic aromatic hydrocarbons (PAHs) as "structure directing agents" to the raw materials. Their polycyclic planar structures can be embedded between aromatic molecular layers, effectively reducing system viscosity, increasing reaction sites, and promoting the interaction between aromatic free radicals and the stacking and fusion of aromatic sheets. This accelerates the nucleation, growth, and fusion of mesophase spheres, directionally inducing the formation of a wide-area streamlined anisotropic structure. Secondly, in the first stage of the segmented heat treatment of this invention, the temperature is slowly increased and held at a relatively high pressure to promote the in-depth dehydrogenation and condensation reaction of aromatic molecules, forcing the reaction to proceed in the direction of generating large-sized mesophase, and effectively suppressing the volatilization of light components and coking side reactions, ensuring the uniformity and orderliness of the system reaction, so that the mesophase can grow and develop fully; in the second stage, appropriate temperature and pressure are used to provide suitable fluidity for the formed large-sized mesophase spheres, so that they can fully merge and oriented, and finally solidify the perfect mesophase morphology into needle-shaped coke with a highly ordered microcrystalline structure, excellent orientation, high mechanical strength and low coefficient of thermal expansion.

[0008] In a preferred embodiment of the method for preparing needle coke raw coke according to the present invention, the heavy aromatic feedstock includes at least one of ethylene tar, coal tar, vacuum slurry from needle coke unit, catalytic cracking slurry, and slurry bed residue.

[0009] In a preferred embodiment of the method for preparing needle coke of the present invention, the mass percentage of the aromatic component in the heavy aromatic raw material is ≥25wt%.

[0010] As a preferred embodiment of the method for preparing needle-shaped coke according to the present invention, the chromatography separation includes the following steps: eluting the heavy aromatic raw material sequentially with a first eluent and a second eluent, collecting the components eluted with the second eluent, concentrating, and obtaining the aromatic components; the first eluent includes at least one of n-hexane, cyclohexane, n-heptane, and n-pentane; the second eluent includes dichloromethane and / or toluene.

[0011] In a preferred embodiment of the method for preparing needle-shaped char from the present invention, the polycyclic aromatic hydrocarbon compound includes at least one of 1-chloronaphthalene, anthracene, phenanthrene, pyrene, and perylene.

[0012] In a preferred embodiment of the method for preparing needle-shaped coke according to the present invention, the mass of the polycyclic aromatic hydrocarbon compound is 10%-15% of the total mass of the mixed components.

[0013] Preferably, the mass of the polycyclic aromatic hydrocarbon compound is a range of 10%, 11%, 12%, 13%, 14%, or 15% of the total mass of the mixed components, or a range of both.

[0014] In the preparation method of needle coke of this invention, the amount of polycyclic aromatic hydrocarbon compound added is a key parameter that has been precisely optimized. When its mass is within the above-mentioned range, it can effectively improve the aromaticity of the system, act as a structure directing agent to promote the generation and interaction of aromatic free radicals, and provide sufficient impetus for the formation, rapid growth and orderly fusion of mesophase microspheres, ultimately producing high-quality needle coke with higher crystallinity and tighter interlayer packing of microcrystals. When the amount added is too high, it will cause the viscosity of the system to decrease excessively, which is not conducive to the stable fusion of mesophase microspheres, will destroy the continuity of the reaction system, seriously hinder the development of subsequent ordered structures, and at the same time, the economic benefits will decrease due to increased costs. When the amount added is too low, its effect of improving aromaticity and inducing nucleation is not obvious, and it is difficult to effectively promote the formation of the mesophase, resulting in insufficient growth impetus, slow and insufficient development of mesophase microspheres, and ultimately making it difficult for the fusion process to proceed in an orderly manner, and failing to form the required wide-area streamlined structure.

[0015] In a preferred embodiment of the method for preparing needle-shaped coke according to the present invention, the gas flow rate of the inert atmosphere is 80 mL / min-150 mL / min.

[0016] Preferably, the gas flow rate of the inert atmosphere is 100 mL / min.

[0017] Preferably, the inert atmosphere is nitrogen.

[0018] In a preferred embodiment of the method for preparing needle-shaped coke according to the present invention, the first stage of heat treatment is to raise the temperature to 500°C at a rate of 2°C / min under a pressure of 0.8MPa and hold it at that temperature for 2 hours; the second stage of heat treatment is to raise the temperature to 460°C and the pressure to 0.4MPa.

[0019] Secondly, the present invention provides needle-shaped coke prepared by the preparation method described above.

[0020] Thirdly, the present invention provides the application of the aforementioned needle-shaped coke in graphite electrode materials, carbon sealing materials, and aerospace materials.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the method for preparing needle coke green coke of this invention achieves the preparation of high-quality needle coke green coke with highly ordered microcrystalline structure, excellent orientation, high mechanical strength and low coefficient of thermal expansion through the synergistic optimization of precise raw material control, mesophase orientation induction and segmented heat treatment. It solves the problems of uneven mesophase development, insufficient anisotropy and unstable performance in the traditional needle coke green coke preparation process, and provides a high-performance and cost-controllable raw material solution for high-end fields such as ultra-high power graphite electrodes and lithium-ion battery anode materials, with significant economic and social benefits.

[0022] Secondly, the needle-shaped coke prepared by the method of the present invention has a highly developed anisotropic and ordered microcrystalline structure. Its macroscopic morphology is coarse streamline, and its microscopic carbon layers are tightly stacked with small interlayer spacing. The (002) crystal plane diffraction peak intensity is high and the peak shape is sharp. Its graphitization degree is high and the crystal integrity is good. Moreover, the prepared needle-shaped coke has high mechanical strength, low thermal expansion coefficient and excellent conductivity, which perfectly meets the stringent requirements of ultra-high power graphite electrodes and high-end lithium-ion battery anode materials for raw materials.

[0023] Furthermore, the preparation method of needle coke of the present invention is simple and the components are inexpensive and readily available. It can achieve a leapfrog improvement in the performance of needle coke products with relatively low cost raw material control. This not only reduces the production cost of high-end carbon materials, but also provides downstream industries with high-performance, stable supply and controllable cost core raw materials, which has significant economic value and broad market application prospects. Attached Figure Description

[0024] Figure 1 Comparison of XRD powder diffraction patterns of needle-shaped coke produced in Examples 1-5 and Comparative Example 1 of this invention; Figure 2 The XRD powder diffraction pattern of the needle-shaped coke prepared in Example 1 of this invention; Figure 3 The XRD powder diffraction pattern of the needle-shaped coke prepared in Example 2 of this invention; Figure 4 The XRD powder diffraction pattern of the needle-shaped coke prepared in Example 3 of this invention; Figure 5 The XRD powder diffraction pattern of the needle-shaped coke prepared in Example 4 of this invention; Figure 6 The XRD powder diffraction pattern of the needle-shaped coke prepared in Example 5 of this invention; Figure 7 The XRD powder diffraction pattern of the needle-shaped coke prepared in Comparative Example 1 of this invention; Figure 8 This is the XRD powder diffraction pattern of the needle-shaped coke prepared in Comparative Example 2 of this invention; Figure 9 This is the XRD powder diffraction pattern of the needle-shaped coke produced in Comparative Example 3 of this invention. Detailed Implementation

[0025] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] The following description, in conjunction with specific embodiments, illustrates the practical effects of the present invention.

[0027] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials, reagents, equipment, etc. used are all commercially available unless otherwise specified.

[0028] Example 1: This embodiment prepares a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0029] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0030] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0031] (4) Repeat the above steps 3 times to obtain 59.5g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0032] (5) Accurately weigh 3g of anthracene and 57g of the aromatic component from step (4), add the anthracene to the aromatic component, stir evenly to obtain a mixed component, at which point the addition ratio of anthracene is 5% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0033] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and maintain the temperature for 240min; after the reaction is completed, maintain the gas flow rate at 100mL / min until the reaction system cools down to room temperature.

[0034] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain 26g of needle-shaped coke.

[0035] Example 2: This embodiment prepares a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0036] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0037] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0038] (4) Repeat the above steps 3 times to obtain 59.2 g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90 kPa for 2 hours. Then take them out and cool them for 30 minutes.

[0039] (5) Accurately weigh 6g of anthracene and 54g of the aromatic component from step (4), add the anthracene to the aromatic component, stir evenly to obtain a mixed component, at which point the proportion of anthracene added is 10% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0040] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0041] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain 26.5g of needle-shaped coke.

[0042] Example 3: This embodiment prepares a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0043] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0044] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0045] (4) Repeat the above steps 3 times to obtain 59.3g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0046] (5) Accurately weigh 9g of anthracene and 51g of the aromatic component from step (4), add the anthracene to the aromatic component, stir evenly to obtain a mixed component, at which point the proportion of anthracene added is 15% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0047] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0048] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain 26.8g of needle-shaped coke.

[0049] Example 4: This embodiment prepares a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0050] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0051] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0052] (4) Repeat the above steps 3 times to obtain 59.1g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0053] (5) Accurately weigh 12g of anthracene and 48g of the aromatic component from step (4), add the anthracene to the aromatic component, stir evenly to obtain a mixed component, at which point the proportion of anthracene added is 20% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0054] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0055] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain 27.5g of needle-shaped coke.

[0056] Example 5: This embodiment prepares a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0057] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0058] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0059] (4) Repeat the above steps 3 times to obtain 59.2g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0060] (5) Accurately weigh 6g of pyrene and 54g of the aromatic component from step (4), add the pyrene to the aromatic component, stir evenly to obtain a mixed component, at which point the pyrene addition ratio is 10% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0061] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0062] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain 28.5g of needle-shaped coke.

[0063] Example 6: This embodiment prepares a needle-shaped char, and its preparation method differs from that of Example 2 only in that: in step (6), the following heating program is set: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 540℃ at a heating rate of 5℃ / min and held for 60 min; (the temperature was changed, but other parameters remained the same). Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0064] Example 7: This embodiment prepares a needle-shaped char, and its preparation method differs from that of Example 2 only in that: in step (6), the following heating program is set: First stage: Under nitrogen purging at 1.5 MPa and 100 mL / min, the temperature was increased from room temperature to 5000℃ at a heating rate of 1℃ / min and held for 180 min; (pressure was changed, other parameters remained the same) Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0065] Comparative Example 1: This comparative example prepared a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0066] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0067] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0068] (4) Repeat the above steps 3 times to obtain 59g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0069] (5) Accurately weigh 50g of the aromatic component from step (4) and put it into a quartz glass tube for later use.

[0070] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0071] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain 26g of needle-shaped coke.

[0072] Comparative Example 2: This comparative example prepared a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0073] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0074] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0075] (4) Repeat the above steps 3 times to obtain 59.2g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0076] (5) Accurately weigh 18g of anthracene and 42g of the aromatic component from step (4), add the anthracene to the aromatic component, stir evenly to obtain a mixed component, at which point the proportion of anthracene added is 30% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0077] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0078] (7) Take out the quartz glass tube from the reactor and break the glass tube to obtain needle-shaped coke.

[0079] Comparative Example 3: This comparative example prepared a needle-shaped raw coke, and the preparation method includes the following steps: (1) Prepare a neutral alumina glass chromatography column, wherein the alumina is 400 mesh, the chromatography column is cylindrical, 40 cm high, and 10 cm inner diameter.

[0080] (2) Take 200g of catalytic cracking slurry sample (purchased from Maoming Petrochemical, with a density of 1130.2 kg·m³). -3 The aromatic hydrocarbon content (30wt%) was placed in a 50℃ oven and heated for 5 minutes to make it flowable. Then, n-hexane was added to dissolve it evenly, and the solution was poured into a chromatography column. After it entered the adsorption layer, 1.5L of n-hexane was added to wash the chromatography column for the first time to obtain a saturated component solution. Then, 1.5L of dichloromethane was added to wash the chromatography column for the second time to obtain an aromatic component solution.

[0081] (3) The solvent in the aromatic component solution was removed by a rotary evaporator under the conditions of 65°C water bath and 170r / min.

[0082] (4) Repeat the above steps 3 times to obtain 59.3g of aromatic components. Place them in a vacuum drying oven at 120℃ and keep them under a negative pressure of 90Kpa for 2 hours. Then take them out and cool them for 30 minutes.

[0083] (5) Accurately weigh 1.8g of anthracene and 58.2g of the aromatic component from step (4), add the anthracene to the aromatic component, stir evenly to obtain a mixed component, at which point the proportion of anthracene added is 3% of the total mass of the mixed component; take 50g of the mixed component and put it into a quartz glass tube for later use.

[0084] (6) Place the above-mentioned quartz glass tube into the reactor and set the following heating program: First stage: Under nitrogen purging at 0.8 MPa and 100 mL / min, the temperature was increased from room temperature to 500℃ at a heating rate of 2℃ / min and held for 120 min. Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0085] Remove the quartz glass tube from the reactor and break it to obtain needle-shaped coke.

[0086] Comparative Example 4: This comparative example prepared a needle-shaped char, the only difference between its preparation method and that of Example 2 is that in step (5), anthracene is replaced with an equal amount of naphthalene.

[0087] Comparative Example 5: This comparative example prepared a needle-shaped char, the only difference between its preparation method and that of Example 2 is that in step (6), the following heating program is set: First stage: Under nitrogen purging at 0.8 MPa, 500℃, and 100 mL / min, hold for 120 min; Second stage: Cool down to 460℃, while reducing the pressure to 0.4MPa, and hold for 240 minutes; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0088] Comparative Example 6: This comparative example prepared a needle-shaped char, the only difference between its preparation method and that of Example 2 is that in step (6), the following heating program is set: First stage: Under nitrogen purging at 0.4 MPa, 460℃, and 100 mL / min, hold for 120 min; Second stage: Under nitrogen purging at 0.8 MPa, 500℃, and 100 mL / min, maintain the temperature for 240 min; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0089] Comparative Example 7: This comparative example prepared a needle-shaped char, the only difference between its preparation method and that of Example 2 is that in step (6), the following heating program is set: First stage: Under nitrogen purging at 0.8 MPa, 460℃, and 100 mL / min, hold for 120 min; Second stage: Under nitrogen purging at 0.4 MPa, 500℃, and 100 mL / min, maintain the temperature for 240 min; After the reaction is complete, maintain the gas flow rate at 100 mL / min until the reaction system cools to room temperature.

[0090] Test example: (1) According to YS / T 587.13-2007 XRD detection method for calcined petroleum coke for carbon anodes, the crystal structure parameters of the needle coke prepared in the examples and comparative examples were tested and analyzed.

[0091] Table 1. Crystal structure parameters of needle coke formation in the examples and comparative examples. like Figure 2 As shown, the needle-shaped coke prepared in Example 1 of this invention exhibits a high degree of structural orientation. XRD analysis results show that the diffraction angle 2θ of the (002) crystal plane is 26.07°, and the average interlayer spacing d of the microcrystals is... 002 =0.3416nm, layer stacking height L c =3.2870nm, graphitization degree g=0.2803. Compared with the needle-shaped raw coke of Comparative Example 1 (2θ=25.95°, d002=0.3432nm, layer stacking height Lc=3.3073nm, g=0.0923), all structural parameters are significantly improved. The increase in diffraction angle and decrease in interlayer spacing of the needle-shaped raw coke in Example 1 of this invention indicate that the carbon layers are more tightly stacked. The increase in stacking height reflects the promotion of ordered growth of crystals in the C-axis direction. The higher graphitization degree directly proves that its microstructure is closer to that of ideal graphite. This shows that the addition of the optimized components of this invention effectively guides the directional arrangement of aromatic molecules, promotes the fusion and development of mesophase spheres, and ultimately forms a high-quality needle-shaped raw coke with significant anisotropy and a coarse streamlined macroscopic morphology.

[0092] like Figure 3 As shown, Example 2 of this invention yielded a needle coke raw coke product with the best overall performance, exhibiting a diffraction angle 2θ of 26.17° on the (002) crystal plane, and a reduction in the average interlayer spacing of the microcrystals to d. 002 =0.3404nm, layer stacking height L c =3.7173nm, graphitization degree g=0.4190, all parameters are far superior to Comparative Example 1 and most other embodiments. In particular, the (002) diffraction peak of the needle-shaped raw coke in Embodiment 2 of the present invention not only has a better peak position, but also exhibits higher intensity and narrower half-width at half-maximum. This clearly indicates that the aromatic lamellae in the coke have excellent orientation consistency and larger crystallite size. The addition of the optimized components of the present invention enables the system to provide sufficient nucleus templates to guide highly ordered molecular arrangement while maintaining suitable rheological properties, thereby allowing the mesophase microspheres to fully fuse, grow and orient during heat treatment, ultimately generating needle-shaped raw coke with a highly developed crystal structure and excellent quality.

[0093] like Figure 4 As shown, the needle-shaped coke prepared in Example 3 of this invention has a diffraction angle 2θ of 26.04° on the (002) crystal plane, and the average interlayer spacing of the microcrystals is reduced by d. 002 =0.3420nm, layer stacking height L c=3.6106nm, graphitization degree g=0.2383. Although the graphitization degree decreased compared to Example 2, its layer stacking height (Lc) remained at a high level, and the diffraction peak shape was narrow, indicating that the aromatic sheets had good directionality and relatively more anisotropic flow-type textured structures, and the oil slurry was more likely to transform from an amorphous carbon structure to a graphite-like structure.

[0094] like Figure 5 As shown, the needle-shaped coke prepared in Example 4 of this invention maintains a basic orientation structure, with a diffraction angle 2θ of 26.01° on the (002) crystal plane, and the average interlayer spacing of the microcrystals is reduced by d. 002 =0.3424nm, layer stacking height L c =2.8793nm, graphitization degree g=0.1918. Compared with the needle coke produced in Comparative Example 1 (2θ=25.95°, d002=0.3432nm, layer stacking height Lc=3.3073nm, g=0.0923), the needle coke produced in Example 4 of this invention has a higher degree of orientation and more anisotropic flow-type texture structure. The oil slurry is more likely to transform from an amorphous carbon structure to a graphite-like structure, but the layer stacking height Lc (2.8793nm) shows a significant decrease.

[0095] like Figure 6 As shown, this embodiment explores another effect of optimizing the pyrene composition, which has a diffraction angle 2θ of 26.02° on the (002) crystal plane, and the average interlayer spacing of the microcrystals is reduced by d. 002 =0.3422nm, layer stacking height L c =3.7263nm, graphitization degree g=0.2038. This means that pyrene is also an effective optimizing component, which can significantly promote the longitudinal growth of microcrystals and has an excellent effect on forming a tightly stacked carbon layer structure.

[0096] like Figure 7 As shown, the needle-shaped coke produced in Comparative Example 1 of this invention has a diffraction angle 2θ of 25.95°, and the average interlayer spacing of the microcrystals is reduced by d. 002 =0.3432nm, layer stacking height L c =3.3073 nm, graphitization degree g=0.0923. This result clarifies that the unoptimized raw materials have limited inherent coking ability, and the coke prepared has relatively low crystal structure order, graphitization tendency and microcrystal development.

[0097] like Figure 8 As shown, the diffraction angle 2θ of the needle-shaped coke prepared in Comparative Example 2 of this invention is 26.9°, and the average interlayer spacing of the microcrystals is d. 002 =0.345nm, layer stacking height L c=3.3063nm, graphitization degree g=0.02. For example... Figure 9 As shown, the diffraction angle 2θ of the needle-shaped coke prepared in Comparative Example 3 of this invention is 26.92°, and the average interlayer spacing of the microcrystals is d. 002 =0.343nm, layer stacking height L c =3.3048nm, graphitization degree g=0.050. This result clarifies that adding too much or too little of the optimized component in this invention will destroy the optimization effect, leading to an imbalance in the system composition, changes in the reaction path, and factors that inhibit ordering. As a result, the structural order of the generated coke may not even reach the level of the basic raw materials, and the optimization effect is completely lost.

[0098] (2) True density test The true density of the needle coke prepared in the examples and comparative examples was determined according to GB / T 6155-2008.

[0099] (3) Thermal expansion coefficient test The coefficient of thermal expansion of the needle coke prepared in the examples and comparative examples was determined according to GB / T 3074.4-2016.

[0100] Table 2. Performance test results of needle coke formation in the examples and comparative examples. As shown in Table 2, the high true density of the needle coke in the embodiments of the present invention reflects the compactness of the product structure, while the extremely low coefficient of thermal expansion indicates that it has excellent thermal stability and thermal shock resistance. This is crucial for ultra-high power graphite electrodes used under extreme conditions such as high temperature and high current load. The needle coke in the embodiments of the present invention is significantly superior to the comparative example in terms of structure and key performance. This indicates that the preparation method of the needle coke in the present invention, through precise control of raw material composition and synergistic optimization of process, has successfully prepared high-quality needle coke with a highly ordered microcrystalline structure, high true density, and low coefficient of thermal expansion. Moreover, its process is simple, easy to operate and control, which is conducive to the stable and large-scale production of high-quality needle coke products and can continuously meet the stringent requirements of downstream lithium-ion battery anode and electric arc furnace steelmaking fields for high-performance raw materials.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing needle-shaped char, characterized in that, Includes the following steps: S1. The heavy aromatic hydrocarbon feedstock is separated by chromatography to obtain aromatic components; S2. The aromatic component and the polycyclic aromatic hydrocarbon compound are mixed to obtain a mixed component; the mass of the polycyclic aromatic hydrocarbon compound is 5%-20% of the mass of the mixed component. S3. Under an inert atmosphere, the mixed components are subjected to segmented heat treatment to obtain the needle-shaped coke; the segmented heat treatment includes a first stage heat treatment and a second stage heat treatment. The first stage of heat treatment involves heating to 480℃-540℃ at a rate of 1℃ / min-5℃ / min under a pressure of 0.7MPa-1.5MPa, and holding at that temperature for 1h-3h; the second stage of heat treatment involves a temperature of 450℃-475℃ and a pressure of 0.3MPa-0.5MPa.

2. The method for preparing needle-shaped char as described in claim 1, characterized in that, The heavy aromatic feedstock includes at least one of ethylene tar, coal tar, vacuum slurry from needle coke units, catalytic cracking slurry, and slurry bed residue.

3. The method for preparing needle-shaped char as described in claim 1, characterized in that, The mass percentage of the aromatic components in the heavy aromatic feedstock is ≥25wt%.

4. The method for preparing needle-shaped char as described in claim 1, characterized in that, The chromatography separation includes the following steps: eluting the heavy aromatic raw material sequentially with a first eluent and a second eluent, collecting the components eluted with the second eluent, concentrating them, and obtaining the aromatic components; the first eluent includes at least one of n-hexane, cyclohexane, n-heptane, and n-pentane; the second eluent includes dichloromethane and / or toluene.

5. The method for preparing needle-shaped char as described in claim 1, characterized in that, The polycyclic aromatic hydrocarbon compound includes at least one of 1-chloronaphthalene, anthracene, phenanthrene, pyrene, and perylene.

6. The method for preparing needle-shaped char as described in claim 1, characterized in that, The mass of the polycyclic aromatic hydrocarbon compound is 10%-15% of the mass of the mixed components.

7. The method for preparing needle-shaped char as described in claim 1, characterized in that, The gas flow rate of the inert atmosphere is 80 mL / min to 150 mL / min.

8. The method for preparing needle-shaped char as described in claim 1, characterized in that, The first stage of heat treatment involves heating to 500°C at a rate of 2°C / min under a pressure of 0.8 MPa and holding at that temperature for 2 hours; the second stage of heat treatment involves a temperature of 460°C and a pressure of 0.4 MPa.

9. Needle-shaped coke prepared by the preparation method according to any one of claims 1-8.

10. The application of the needle-shaped coke as described in claim 9 in graphite electrode materials, carbon sealing materials, and aerospace materials.

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