A method for preparing a spinnable mesophase pitch based on co-carbonization of coal tar pitch and catalytic cracking slurry oil

Abstract

The present application belongs to the technical field of petroleum processing and the field of carbon material preparation, and discloses a preparation method of spinnable mesophase pitch based on co-carbonization of coal tar pitch and catalytic cracking slurry. Coal tar pitch and xylene-soluble components of coal tar pitch extracted by xylene are mixed with catalytic cracking slurry, and then co-carbonization reaction is carried out. The reaction product is crushed, secondarily extracted, filtered, and then subjected to low-temperature heat treatment to obtain spinnable mesophase pitch. Through raw material cooperation and multi-stage purification process, the present application realizes high content, high spinnability and structure controllability of mesophase pitch, and the process is simple, environmentally friendly and economical, and is suitable for large-scale production of high-performance pitch-based carbon fiber.

Description

Technical Field

[0001] This invention belongs to the fields of petroleum processing technology and carbon material preparation, and relates to a method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry. Background Technology

[0002] Mesophase pitch is an important precursor for the preparation of high-performance pitch-based carbon fibers. Its structural composition, anisotropy, and rheological properties directly affect the fiber's fiber-forming stability, orientation structure, and mechanical properties. For spinnable mesophase pitch, it is generally required to simultaneously possess a high mesophase content, a moderate softening point, a low impurity content, and good melt flowability to meet the requirements of continuous and stable spinning. Currently, the raw materials used to prepare mesophase pitch mainly include coal tar pitch, petroleum pitch, catalytic cracking slurry, ethylene tar, and naphthalene pitch. These raw materials are generally rich in aromatic structures and are important carbon sources for the preparation of mesophase pitch, but they also have problems such as wide molecular weight distribution, complex structural composition, high impurity content, and difficulty in controlling spinnability. In existing technologies, to improve the anisotropy content of mesophase pitch, methods such as increasing the aromaticity of the raw materials, enhancing the degree of thermal polycondensation reaction, or combining extraction, sedimentation, hydrogenation modification, and supercritical extraction are commonly used to control the raw materials or products.

[0003] To improve the spinnability and quality of mesophase pitch, researchers have developed various process routes. For example, CN114854444B discloses a method for preparing mesophase pitch using coal / heavy oil hydrorefining residue. This method involves obtaining soluble matter through toluene extraction, followed by sequential thermal polycondensation and thermal sedimentation separation, ultimately achieving efficient enrichment of anisotropic components. This method utilizes coal / oil co-refining residue as a low-cost raw material and significantly improves the content (>95%) and structural uniformity of mesophase pitch through thermal sedimentation. However, the sedimentation separation efficiency of this process is greatly affected by temperature and time, and the use of toluene extractant brings recycling and environmental pressures, limiting large-scale continuous production. CN119639475B discloses a method for preparing spinnable mesophase pitch, which employs a combined process of catalytic cracking slurry undergoing vacuum fractionation, hydrogenation reforming of the light fraction, supercritical extraction of the heavy fraction, and then co-carbonization of the two. This method improves the broad-area structure content and spinnability of mesophase pitch by controlling the aromatic structure and reaction synergy of the raw materials, achieving high-value utilization of the whole-fraction oil slurry. However, the process route is still complex, involving multiple separation and reaction units, and has high requirements for the stability of raw material properties, increasing the difficulty of system integration and operation control. CN120624044A discloses a method for preparing high-quality mesophase pitch from ethylene tar as raw material. After cutting the raw material by vacuum distillation, a solvent-precipitant system is used to induce the pre-aggregation of polycyclic aromatic hydrocarbons at room temperature, followed by centrifugal separation to obtain the precursor, and finally thermal polycondensation reaction under Lewis acid catalysis. This effectively improves the yield and anisotropy content of mesophase pitch (up to 50-100%), and reduces the amount of catalyst used. However, its process still involves multiple separation steps and solvent recovery, and uses toxic solvents such as quinoline, which has limitations in terms of environmental protection and operational economy.

[0004] In existing technologies, the preparation of mesophase pitch mainly relies on increasing the aromaticity of the raw materials or enhancing the degree of polycondensation reaction. However, these methods usually lead to reduced system fluidity, making it difficult to achieve continuous and stable spinning. Furthermore, while methods such as hydrogenation or supercritical extraction can improve fluidity, these processes are complex and costly. Therefore, developing a method to simultaneously achieve high mesophase content and excellent spinnability under simplified process conditions is of great significance. Summary of the Invention

[0005] This invention aims to provide a method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry. By optimizing the raw material ratio and process route, the method achieves efficient utilization of raw materials and structural synergy, thereby improving the spinnability and overall performance of the mesophase pitch.

[0006] The technical solution of this invention: A method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil includes the following steps: Step 1: Mix coal tar pitch and xylene at a mass ratio of 1:8 to 1:12 and extract at 30 to 60°C for 2 to 4 hours. After extraction, filter the mixture using a 0.2 μm filter bag, collect the filtrate, and remove the xylene solvent from the filtrate to obtain the xylene-soluble component of coal tar pitch. Step 2: Mix the catalytic cracking slurry with the coal tar pitch xylene soluble component obtained in Step 1 at a mass ratio of 3:7 to 7:3. Place the mixture in a high-pressure reactor and heat-treat it for 4 to 10 hours at a temperature of 400 to 450°C and a pressure of 2 MPa under an inert atmosphere. After the reaction is completed, cool it down rapidly to obtain co-carbonized pitch. Step 3: Crush the cocarbonized pitch obtained in Step 2, pass it through a 30-200 mesh sieve, mix the cocarbonized pitch with the extractant at a mass ratio of 1:3 to 1:15, and extract in a water bath at 20-60℃ for 1-4 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 320-400℃ at a rate of 10℃ / min under an inert atmosphere and heat it for 10-60 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0007] In step 1, the quinoline insoluble content in the coal tar pitch xylene soluble component is less than 0.5 wt.%, the C / H atomic ratio is 1.60 to 2.00, and the aromaticity index fa ≥ 0.85.

[0008] In step 2, the catalytic cracking slurry is an aromatic system rich in alkyl side chains and cycloalkane structures. 1 H-NMR characterization results showed that the aromaticity index of the soluble component of coal tar pitch xylene was higher than that of the catalytic cracking slurry, and the difference between the two aromaticity indices was preferably 0.2 to 0.35. Meanwhile, the total relative content of aliphatic side-chain hydrogens and cycloalkane hydrogens in the catalytic cracking slurry was higher than that of the soluble component of coal tar pitch xylene.

[0009] In steps 1 and 2, the coal tar pitch and catalytic cracking slurry may be derived from different raw materials or different process conditions, and their aromaticity index and hydrogen distribution may differ to some extent, but they still satisfy the structural matching relationship described in this invention.

[0010] In step 2, the preferred mass ratio of the catalytic cracking slurry to the soluble component of coal tar pitch xylene is 4:6 to 6:4.

[0011] In step 2, the heat treatment temperature is preferably 420–440℃, the reaction time is preferably 5–8 h, and the pressure is preferably 0.5–1.5 MPa.

[0012] In step 2, the inert atmosphere is nitrogen or argon.

[0013] In step 3, the co-carbonized asphalt is crushed and passed through a 50-100 mesh sieve. The extractant is one or more of n-octane, toluene, and xylene. The mass ratio of co-carbonized asphalt to extractant is preferably 1:5 to 1:10. The extraction temperature is preferably 30-50℃. The extraction time is preferably 1-3 hours.

[0014] In step 4, the inert atmosphere is nitrogen or argon, the reaction temperature is preferably 350-380℃, and the heat treatment time is 15-30 min.

[0015] In this invention, each step has a clear functional division and synergistic relationship in the construction of the mesophase asphalt structure: (1) Step 1 removes the sparingly soluble high condensation components in coal tar pitch by xylene extraction, reduces the content of quinoline insoluble matter, and obtains aromatic structural units with relatively uniform structure and potential for mesophase formation, providing a basis for subsequent structure construction.

[0016] (2) Step 2 achieves the synergistic effect between different molecular structures through the co-carbonization reaction of the xylene soluble component of coal tar pitch and catalytic cracking slurry. Coal tar pitch provides a rigid structural unit with high aromaticity, while catalytic cracking slurry provides a flexible component rich in alkyl side chains and cycloalkane structures, thereby constructing an intermediate phase precursor system with both aromatic stacking ability and molecular fluidity.

[0017] (3) Step 3 removes low molecular weight components and isotropic components from the co-carbonized product through secondary extraction, regulates the molecular weight distribution of the product, realizes the hierarchical enrichment of the intermediate phase structure, and transforms the anisotropic structure from a dispersed state to a continuous structure.

[0018] (4) Step 4 induces the ordered arrangement and rearrangement of aromatic structural units through low-temperature heat treatment, thereby improving the structural order while avoiding excessive rigidity of the system and ensuring good spinnability.

[0019] There is a clear structural regulation dependency among the above steps. Step 1 is used to screen the precursor structure; step 2 is used to achieve the synergistic co-carbonization of rigid aromatic structural units and flexible side-chain structural units; step 3 is used to achieve molecular weight distribution regulation and anisotropic component enrichment; and step 4 is used to achieve ordered structural rearrangement. The absence of key steps may lead to a decrease in the continuity of the mesophase structure or an imbalance in fluidity. Therefore, this invention is not a simple combination of individual processes in the prior art, but rather a holistic technical solution with a synergistic regulation mechanism.

[0020] The beneficial effects of this invention are: (1) This invention achieves the synergistic construction of rigid aromatic structural units and flexible side-chain structural units through the structural complementarity of the coal tar xylene soluble component and the catalytic cracking slurry. The coal tar xylene soluble component provides a high-aromaticity rigid structure, which is beneficial for the formation of the mesophase structure, while the catalytic cracking slurry provides a flexible component rich in alkyl side chains and cycloalkane structures, which is beneficial for improving the melt flowability of the system. Comparative results show that when only the coal tar xylene soluble component is used, the system rigidity is enhanced, the softening point is increased (approximately 305℃), and the continuous spinning length is <300m; when only the catalytic cracking slurry is used, the mesophase content is 70%, making it difficult to form a continuous anisotropic structure. However, under the dual-component synergistic system described in this invention, a mesophase content ≥95%, a softening point of 260–300℃, and a continuous spinning length >5000m can be achieved simultaneously, indicating that the two raw materials are not simply superimposed, but rather maintain suitable melt flowability while increasing the mesophase content through structural complementarity.

[0021] (2) This invention gradually removes quinoline insolubles and isotropic components through selective extraction in the early stage, secondary extraction after co-carbonization, and low-temperature heat treatment, thereby achieving hierarchical enrichment of the mesophase precursor and promoting the orderly rearrangement of aromatic structural units. When secondary extraction or low-temperature heat treatment is lacking, the low molecular weight components and isotropic components in the obtained product are not effectively removed or the structural order is insufficient, resulting in a decrease in the mesophase content or a deterioration in spinning stability, indicating that the above steps play a key role in the structure construction process.

[0022] (3) This invention does not require complex process units such as hydrogenation or supercritical extraction. It can effectively enrich the mesophase precursor simply through selective extraction, co-carbonization, secondary extraction and low-temperature heat treatment. The whole process is mild, simple and stable, and has good prospects for scale-up applications. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described below in conjunction with the technical solution.

[0024] The raw materials used in the embodiments and comparative examples of this invention are catalytic cracking slurry oil and soluble components of coal tar pitch xylene, the specific properties of which are shown in Tables 1 and 2. Unless otherwise stated, the catalytic cracking slurry oil and soluble components of coal tar pitch xylene used in the following embodiments and comparative examples are the raw materials shown in Tables 1 and 2. If the source of the raw materials or the structural parameters are different, it will be described separately in the corresponding embodiments or comparative examples.

[0025] Table 1 Basic properties of the two raw materials

[0026] Table 2 Two raw materials based on 1 Hydrogen distribution calculated by H-NMR

[0027] As shown in Tables 1 and 2, under default feedstock conditions, the C / H atomic ratio of catalytic cracking slurry is low, and the H... γ H β H α and H N The content of aromatic hydrogens in the xylene-soluble component of coal tar pitch is significantly higher than that in the soluble component of coal tar pitch, indicating that its molecule contains more alkyl side chains and cycloalkane structures, exhibiting better molecular flexibility. Meanwhile, the aromatic hydrogen content in the soluble component of coal tar pitch is significantly higher, and the aromaticity index is also higher. f a The value reached 0.92, indicating that its molecular structure is mainly composed of fused-ring aromatic structures, possessing strong aromatic stacking ability and structural rigidity. The two raw materials have significant differences in molecular structure, and can respectively provide flexible structural units and rigid aromatic structural units, laying the foundation for constructing a synergistic system with both mesophase forming ability and melt flowability in the subsequent co-carbonization process.

[0028] Example 1 Step 1: Mix 100g of coal tar pitch with 1kg of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thereby obtaining the xylene-soluble component of coal tar pitch. Step 2: Take 60g of catalytic cracking slurry and mix it evenly with 60g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 5:5). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 7 hours under a nitrogen atmosphere at 430℃ and 1MPa. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 60-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:10 and extract in a 50°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 380°C at a rate of 10°C / min under an inert atmosphere and heat it for 30 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0029] Testing revealed that the obtained mesophase pitch had a softening point of 285℃, a C / H atomic ratio of 1.89, a mesophase content >97%, and a continuous spinning length >5000m. Furthermore, the graphite fibers produced from it exhibited a tensile modulus of 650 GPa and an axial thermal conductivity of 780 W / m·K. This indicates that under these conditions, isotropic components can be effectively removed, and the continuous formation of anisotropic structures can be promoted, simultaneously achieving high mesophase content and excellent spinnability.

[0030] Comparative Example 1 Step 1: Mix 100g of coal tar pitch with 1kg of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thereby obtaining the xylene-soluble component of coal tar pitch. Step 2: Take 60g of the xylene-soluble component of the coal tar pitch obtained in Step 1 and place it in a high-pressure reactor. After replacing the air with nitrogen, heat-treat it for 7 hours under a nitrogen atmosphere at a temperature of 430℃ and a pressure of 1MPa. After the reaction is completed, rapidly cool down to obtain pyrolytic pitch. This pyrolytic pitch is the product obtained without the introduction of catalytic cracking slurry for co-carbonization. Step 3: After crushing the pyrolytic asphalt obtained in Step 2, pass it through a 60-mesh sieve. Mix the pyrolytic asphalt powder with the extractant at a mass ratio of 1:10 and extract in a 50°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 380°C at a rate of 10°C / min under an inert atmosphere and heat it for 30 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0031] Testing revealed that the obtained mesophase pitch had a softening point of 305℃, a mesophase content of 80%, a C / H atomic ratio of 2.22, and a continuous spinning length of <300m. Furthermore, the graphite fibers produced from it exhibited a tensile modulus of 380 GPa and an axial thermal conductivity of 420 W / m·K. Compared to Example 1, without the introduction of catalytic cracking slurry, the softening point of the product was significantly increased, while the mesophase content and continuous spinning performance decreased significantly. This indicates that relying solely on high-aromatic raw materials easily leads to increased system rigidity and insufficient fluidity, making it difficult to balance mesophase structure construction and spinnability. Therefore, the introduction of catalytic cracking slurry is not a simple raw material substitution, but rather a synergistic regulatory effect on the system's molecular structure and rheological behavior through the participation of flexible structural units in the co-carbonization reaction.

[0032] Comparative Example 2 Step 1: Place 100g of catalytic cracking slurry in a high-pressure reactor, purge the air with nitrogen, and heat-treat for 7 hours under a nitrogen atmosphere at 430℃ and 1MPa. After the reaction, rapidly cool down to obtain pyrolytic asphalt, which is the product obtained by co-carbonization without the introduction of coal tar pitch xylene soluble components. Step 2: After crushing the pyrolytic asphalt obtained in Step 1, pass it through a 60-mesh sieve. Mix the pyrolytic asphalt powder with the extractant at a mass ratio of 1:10 and extract in a 50°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 3: After drying the insoluble material obtained in Step 2, heat it to 380°C at a rate of 10°C / min under an inert atmosphere and heat it for 30 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0033] Testing revealed that the obtained mesophase pitch had a softening point of 298℃, a mesophase content of 70%, a C / H atomic ratio of 1.82, and a continuous spinning length of <100m. Furthermore, the graphite fibers produced from it exhibited a tensile modulus of 330 GPa and an axial thermal conductivity of 400 W / m·K. Compared to Example 1, the spinning continuity was poor. This result indicates that it is difficult to obtain a high mesophase content when using only catalytic cracking slurry as raw material, and the resulting mesophase pitch is inferior to the co-carbonization system described in this invention in terms of melt flow stability and continuous spinning performance.

[0034] The results of Comparative Examples 1 and 2 show that although the soluble components of coal tar pitch xylene have high aromaticity and the catalytic cracking slurry has high side chain content, it is difficult to achieve both high content of mesophase and excellent spinnability by using either raw material alone. The above properties can only be obtained under the structural combination and process conditions defined in this invention.

[0035] Comparative Example 3 Step 1: Mix 100g of coal tar pitch (from a different source than in Example 1) with 1kg of xylene, extract at 50℃ for 3h, filter through a 0.2μm filter bag after extraction, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, obtaining the xylene-soluble component of the coal tar pitch; after elemental analysis and... 1 H-NMR characterization showed the aromaticity index of the soluble component. f a The atomic value is 0.80, and the C / H atomic ratio is 1.51; Step 2: Take 60g of catalytic cracking slurry and mix it evenly with 60g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 5:5). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 7 hours under a nitrogen atmosphere at 430℃ and 1MPa. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 60-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:10 and extract in a 50°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 380°C at a rate of 10°C / min under an inert atmosphere and heat it for 30 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0036] Testing revealed that the obtained mesophase pitch had a softening point of 310℃, a mesophase content of 75%, a C / H atomic ratio of 2.27, and a continuous spinning length of less than 500m, making continuous and stable spinning difficult. Furthermore, the graphite fibers produced from it exhibited a tensile modulus of 350 GPa and an axial thermal conductivity of 380 W / m·K. These results indicate that even under the same process conditions as in Example 1, when the aromaticity index and C / H atomic ratio of the soluble components of coal tar pitch are low, it is still difficult to obtain a product with both high mesophase content and excellent spinnability. This demonstrates that the matching relationship of raw material structure has a significant impact on the realization of the technical solution of this invention.

[0037] Comparative Example 4 Step 1: Mix 100g of coal tar pitch with 1kg of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thereby obtaining the xylene-soluble component of coal tar pitch. Step 2: Take 60g of catalytic cracking slurry and mix it evenly with 60g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 5:5). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 7 hours under a nitrogen atmosphere at 430℃ and 1MPa. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Testing revealed that the co-carbonized product had a softening point of 180°C, a mesophase content of 60%, and a C / H atomic ratio of 1.67, making it unsuitable for spinning. Compared to Example 1, Comparative Example 4 did not undergo subsequent secondary extraction and low-temperature heat treatment. The resulting product did not effectively remove low-molecular-weight and isotropic components, exhibiting insufficient structural continuity, a low softening point, and a low mesophase content, failing to meet the requirements for continuous spinning. This indicates that high-quality spinnable mesophase pitch cannot be directly obtained through co-carbonization alone; subsequent secondary extraction and low-temperature heat treatment play a crucial role in achieving hierarchical enrichment of the structure and the formation of a continuous anisotropic structure.

[0038] Comparative Example 5 Step 1: Mix 100g of coal tar pitch with 1kg of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thereby obtaining the xylene-soluble component of coal tar pitch. Step 2: Take 60g of catalytic cracking slurry and mix it evenly with 60g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 5:5). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 7 hours under a nitrogen atmosphere at 430℃ and 1MPa. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 60-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:10 and extract in a 50°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble matter obtained in Step 3, collect it directly without further low-temperature heat treatment.

[0039] The product tested had a softening point of 268℃, a mesophase content of 88%, a C / H atomic ratio of 1.79, a continuous spinning length of <500m, and poor spinning stability. The resulting graphite fiber had a tensile modulus of 480GPa and an axial thermal conductivity of 600W / m·K. Compared to Example 1, Comparative Example 5, although removing some low-molecular-weight and isotropic components through secondary extraction, lacked a subsequent low-temperature heat treatment step. As a result, the aromatic structural units in the system failed to undergo further ordered rearrangement, and the structural continuity and orientation of the obtained product were still insufficient, making it difficult to form mesophase pitch with both high mesophase content and excellent spinnability. These results indicate that the low-temperature heat treatment in this invention is not a simple post-treatment step, but a crucial step in promoting structural ordering and improving continuous spinning performance.

[0040] Example 2 Step 1: Mix 100g of coal tar pitch with 1kg of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thereby obtaining the xylene-soluble component of coal tar pitch. Step 2: Take 60g of catalytic cracking slurry and mix it evenly with 40g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 6:4). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 8 hours at 430℃ and 2MPa under a nitrogen atmosphere. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 50-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:5 and extract in a 30°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 360°C at a rate of 10°C / min under an inert atmosphere and heat it for 20 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0041] Tests showed that the softening point of the mesophase pitch was 293℃, the mesophase content was >97%, the C / H atomic ratio was 2.04, the continuous spinning length was >8000m, and the graphite fiber made from it had a tensile modulus of 720GPa and an axial thermal conductivity of 920W / m·K.

[0042] Example 3 Step 1: Mix 100g of coal tar pitch with 1200g of xylene and extract at 60℃ for 4h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thereby obtaining the xylene-soluble component of coal tar pitch. Step 2: Take 30g of catalytic cracking slurry and mix it evenly with 70g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 3:7). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 10 hours under a nitrogen atmosphere at 400℃ and atmospheric pressure. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 30-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:15 and extract in a 20°C water bath for 4 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 400℃ at a rate of 10℃ / min under an inert atmosphere and heat it for 10min. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0043] Tests showed that the softening point of the obtained mesophase pitch was 287℃, the mesophase content was >95%, the C / H atomic ratio was 2.00, the continuous spinning length was >6000m, and the tensile modulus of the graphite fiber made from it could reach 600GPa, with an axial thermal conductivity of 720W / m·K.

[0044] Example 4 Step 1: Mix 100g of coal tar pitch with 800g of xylene and extract at 30℃ for 2 hours. After extraction, filter through a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, obtaining the xylene-soluble component of the coal tar pitch. Elemental analysis and... 1 H-NMR characterization showed the aromaticity index of the soluble component. f a The atomic value is 0.90, and the C / H atomic ratio is 1.90.

[0045] Step 2: Take 40g of catalytic cracking slurry (from a different source than in Example 1) and mix it evenly with 60g of the coal tar pitch xylene soluble component obtained in Step 1 (mass ratio 4:6). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat for 5 hours under a nitrogen atmosphere at 440℃ and 0.5MPa. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch; the catalytic cracking slurry used is processed... 1 H-NMR characterization, its aroma index f a If the value is 0.58, then the difference in the aroma index between the two is approximately 0.32.

[0046] Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 200-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:3 and extract in a 50°C water bath for 3 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 370℃ at a rate of 10℃ / min under an inert atmosphere and heat it for 25 minutes. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0047] Tests showed that the softening point of the mesophase pitch was 290℃, the mesophase content was >96%, the C / H atomic ratio was 2.00, the continuous spinning length was >7000m, and the graphite fiber made from it had a tensile modulus of 680GPa and an axial thermal conductivity of 820W / m·K.

[0048] Example 5 Step 1: Mix 100g of coal tar pitch with 1000g of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thus obtaining the xylene-soluble component of coal tar pitch.

[0049] Step 2: Take 70g of catalytic cracking slurry and mix it evenly with 30g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 7:3). Place the mixture in a high-pressure reactor, purge the air with argon gas, and heat-treat it for 4 hours at 450℃ and 1MPa under an argon atmosphere. After the reaction is complete, rapidly cool it to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 30-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:10 and extract in a 60°C water bath for 1 hour. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 320℃ at a rate of 10℃ / min under an inert atmosphere and heat it for 60min. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0050] Tests showed that the softening point of the mesophase pitch was 292℃, the mesophase content was >96%, the C / H atomic ratio was 1.96, the continuous spinning length was >6500m, and the graphite fiber made from it had a tensile modulus of 640GPa and an axial thermal conductivity of 760W / m·K.

[0051] Example 6 Step 1: Mix 100g of coal tar pitch with 1000g of xylene and extract at 50℃ for 3h. After extraction, filter with a 0.2μm filter bag, collect the filtrate, and evaporate the filtrate at 160℃ to remove the xylene solvent, thus obtaining the xylene-soluble component of coal tar pitch.

[0052] Step 2: Take 50g of catalytic cracking slurry and mix it evenly with 50g of the xylene-soluble component of coal tar pitch obtained in Step 1 (mass ratio 5:5). Place the mixture in a high-pressure reactor, purge the air with nitrogen, and heat-treat it for 6 hours under a nitrogen atmosphere at 420℃ and 1.5MPa. After the reaction is complete, rapidly cool down to obtain co-carbonized pitch. Step 3: After crushing the cocarbonized pitch obtained in Step 2, pass it through a 100-mesh sieve. Mix the cocarbonized pitch powder with the extractant at a mass ratio of 1:8 and extract in a 40°C water bath for 2 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 350℃ at a rate of 10℃ / min under an inert atmosphere and heat it for 15min. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

[0053] Tests showed that the softening point of the mesophase pitch was 288℃, the mesophase content was >96%, the C / H atomic ratio was 2.02, the continuous spinning length was >7200m, and the graphite fiber produced from it had a tensile modulus of 660GPa and an axial thermal conductivity of 800W / m·K.

[0054] As can be seen from the above embodiments and comparative examples, the technical solution of the present invention is not a simple superposition of individual steps, but rather an overall control system based on the matching of raw material structures and the synergy of processes. The soluble component of coal tar pitch xylene provides rigid structural units with high aromaticity, while the catalytic cracking slurry provides flexible components rich in alkyl side chains and cycloalkane structures. The two work synergistically in the co-carbonization stage, which is beneficial for constructing a mesophase precursor system with both aromatic stacking ability and melt flowability. Subsequently, low molecular weight components and isotropic components are removed by secondary extraction, and the aromatic structural units are further ordered rearranged by low-temperature heat treatment, thereby obtaining a spinnable mesophase pitch with high mesophase content, moderate softening point, and excellent continuous spinning performance.

[0055] The above description is merely a preferred embodiment of the present invention and does not limit the scope of the patent. Any adjustments to process parameters, raw material substitutions, equivalent equipment replacements, or optimizations of reaction conditions made using the present invention's specifications, or any application of this method to other aromatic raw materials (such as petroleum asphalt, coal tar, ethylene tar, etc.) to prepare spinnable mesophase pitch, all within the inventive concept of the present invention, should be considered within the protection scope of the present invention.

Claims

1. A method for preparing a spinnable mesophase pitch based on coal tar pitch and catalytically cracked oil slurry co-carbonization, characterized by, Includes the following steps: Step 1: Mix coal tar pitch and xylene at a mass ratio of 1:8 to 1:12 and extract at 30 to 60°C for 2 to 4 hours. After extraction, filter the mixture using a 0.2 μm filter bag, collect the filtrate, and remove the xylene solvent from the filtrate to obtain the xylene-soluble component of coal tar pitch. Step 2: Mix the catalytic cracking slurry with the coal tar pitch xylene soluble component obtained in Step 1 at a mass ratio of 3:7 to 7:

3. Place the mixture in a high-pressure reactor and heat-treat it for 4 to 10 hours at a temperature of 400 to 450°C and a pressure of 2 MPa under an inert atmosphere. After the reaction is completed, cool it down rapidly to obtain co-carbonized pitch. Step 3: Crush the cocarbonized pitch obtained in Step 2, pass it through a 30-200 mesh sieve, mix the cocarbonized pitch with the extractant at a mass ratio of 1:3 to 1:15, and extract in a water bath at 20-60℃ for 1-4 hours. After extraction, filter the mixture to obtain insoluble matter. Step 4: After drying the insoluble material obtained in Step 3, heat it to 320-400℃ at a rate of 10℃ / min under an inert atmosphere and heat it for 10-60 min. After the heat treatment is completed, cool it to obtain spinnable mesophase pitch.

2. The method for preparing spinnable mesophase pitch based on co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 1, the quinoline insoluble content in the soluble component of the coal tar pitch xylene is less than 0.5 wt.%, the C / H atomic ratio is 1.6 to 2.0, and the aromaticity index fa ≥ 0.

85.

3. The method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 2, the catalytic cracking slurry is an aromatic system rich in alkyl side chains and cycloalkane structures. The aromatic index of the soluble component of coal tar pitch xylene is higher than that of the catalytic cracking slurry, and the difference between the two aromatic indices is 0.2 to 0.

35. At the same time, the total relative content of aliphatic side chain hydrogen and cycloalkane hydrogen in the catalytic cracking slurry is higher than that of the soluble component of coal tar pitch xylene.

4. The method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 2, the mass ratio of the catalytic cracking slurry to the soluble component of coal tar pitch xylene is 4:6 to 6:

4.

5. The method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 2, the heat treatment temperature is 420–440℃, the reaction time is 5–8h, and the pressure is 0.5–1.5MPa.

6. The method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 2, the inert atmosphere is nitrogen or argon.

7. The method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 3, the co-carbonized asphalt is crushed and passed through a 50-100 mesh sieve. The extractant is one or more of n-octane, toluene, and xylene. The mass ratio of co-carbonized asphalt to extractant is 1:5 to 1:

10. The extraction temperature is 30-50℃ and the extraction time is 1-3 hours.

8. The method for preparing spinnable mesophase pitch based on the co-carbonization of coal tar pitch and catalytic cracking slurry oil according to claim 1, characterized in that, In step 4, the inert atmosphere is nitrogen or argon, the reaction temperature is 350–380°C, and the heat treatment time is 15–30 min.

Images