Process and apparatus for the production of a spinnable mesophase pitch from a rich aromatic heavy oil

Abstract

The present application relates to the technical field of mesophase pitch, and is a method and device for preparing spinnable mesophase pitch from aromatic-rich heavy oil.The present application uses aromatic-rich heavy oil as raw material to prepare mesophase pitch by high-temperature and high-pressure direct thermal polycondensation, controls the nitrogen purging flow during the reaction process to regulate the polycondensation reaction rate, removes potential molecules with the same structure, and thus obtains high-quality spinnable mesophase pitch from aromatic-rich heavy oil with moderate polycondensation degree and no same structure inclusion.The prepared spinnable mesophase pitch from aromatic-rich heavy oil has the characteristics of simple process flow and equipment, low preparation cost, controllable reaction conditions, low softening point, high mesophase content, and easy industrialization.

Description

Technical Field

[0001] This invention relates to the field of mesophase pitch technology, and is a method and apparatus for preparing spinnable mesophase pitch from aromatic heavy oil. Background Technology

[0002] Mesophase pitch is an intermediate liquid crystal formed by the pyrolysis, aromatization, and condensation of heavy aromatic hydrocarbons during liquid-phase carbonization. It typically consists of fused-ring aromatic hydrocarbons arranged in a flattened disc or rod-like array with a relative molecular mass of 400 to 4000, and is also known as "liquid crystal pitch." It exhibits optical anisotropy under a polarizing microscope. Currently, there are various methods for preparing mesophase pitch; seven to eight methods have been reported in the literature. However, based on their main reaction mechanisms, they can be divided into thermal condensation polymerization and catalytic polymerization. Thermal condensation polymerization uses simple heat treatment to generate active free radicals in the reaction system, thereby promoting intermolecular polymerization. Catalytic polymerization, on the other hand, mainly uses a catalyst to form complexes with light aromatic molecules or to protonate them, thereby lowering the activation energy of the polymerization reaction, resulting in a milder reaction process.

[0003] Direct thermal polycondensation is a simple process, but the resulting mesophase asphalt has a high softening point. It requires refining the raw materials to remove impurities, adjusting the molecular structure, and optimizing polymerization conditions to maintain a low-viscosity reaction system for an extended period, thereby lowering the product's softening point. Catalytic modification alters the reaction process, lowering the reaction temperature by over 100°C. The introduced cycloalkane structure improves fluidity and effectively reduces the softening point. However, it suffers from the difficulty in removing Lewis acid catalysts, and the highly corrosive HF / BF3 catalyst places high demands on reaction equipment, necessitating the development of novel catalysts. In summary, due to the excessively high equipment requirements and operational risks of catalytic modification, resulting in high production costs, it is gradually being phased out. Direct thermal polycondensation, through raw material pretreatment and refining, and the controlled multi-stage thermal polycondensation process, can produce high-quality mesophase asphalt.

[0004] Factors affecting the properties of mesophase asphalt mainly include temperature, pressure, time, stirring rate, external magnetic field, and reaction atmosphere. To reduce the volatile content and improve the thermal stability of mesophase asphalt, nitrogen purging is typically employed. However, current polycondensation control methods easily lead to inhomogeneous product properties and poor spinning performance. Excessively high polycondensation temperatures or prolonged polycondensation times can cause over-carbonization of some highly reactive polycondensation components, affecting product performance. Given the wide molecular weight distribution of mesophase asphalt feedstock components and the complexity of the thermal polycondensation reaction during preparation, even slight differences in feedstock composition and process conditions can result in significant differences in product performance. Therefore, for a specific feedstock oil, process control of polycondensation conditions is crucial for obtaining high-quality mesophase asphalt.

[0005] Chinese patent document CN118207014A discloses a method for preparing high-quality mesophase spinning pitch from latent mesophase pitch. Using petroleum heavy residue at 380℃ to 460℃ as raw material, spinnable mesophase pitch is prepared through controlled processes such as thermal polycondensation and high-precision filtration separation. This is further heated and homogenized to obtain high-quality mesophase spinnable pitch. This method converts latent mesophase pitch into mesophase pitch, improving the mechanical and thermal conductivity of mesophase pitch-based carbon fibers without reducing spinning stability. However, this method focuses on the separation and homogenization of the polycondensation product, without controlling or optimizing the conditions of the polycondensation process.

[0006] Chinese patent document CN104804757A discloses a method for preparing mesophase pitch. The method involves mixing dimethyl sulfoxide extract oil and hydrocracking tail oil, and then performing a high-temperature and high-pressure carbonization reaction in a reactor to obtain mesophase pitch. The mesophase pitch prepared by this method has a low softening point, good optical structure, and high mesophase content. However, the reaction temperature and pressure are relatively high, resulting in disadvantages such as high equipment requirements and high energy consumption.

[0007] Chinese patent document CN118048167A discloses a method for preparing mesophase pitch, mesophase pitch and its application. In this method, the debromination reaction of the thermal polycondensation reaction is carried out under a protective gas atmosphere, preferably nitrogen. The specific flow rate of the protective gas is 0.1 L / (min·Kg) to 2.0 L / (min·Kg), and the role of nitrogen is to promote the debromination reaction.

[0008] Chinese patent document CN114410332B discloses a mesophase pitch and its preparation method. The method involves feeding raw pitch into a heat treatment reactor for heat treatment, condensing the resulting oil and tail gas, and storing the light oil (boiling point above 200℃) in a light oil storage tank, while other components (boiling point below 200℃) are sent to a tail gas treatment device. The light oil is then added to a hydrogenation unit for catalytic hydrogenation to obtain hydrogenated light oil. The hydrogenated light oil is then reacted with the raw pitch in a isothermal microwave polymerization reaction to obtain a modified precursor pitch. Finally, the modified precursor pitch is added back into the heat treatment reactor to react and obtain mesophase pitch. This method focuses on controlling the composition of the raw materials, using a hydrogen-donating fraction instead of expensive hydrogen-donating solvents such as tetrahydronaphthalene and decahydronaphthalene. Nitrogen bubbling is a common devolatilization process, therefore, this method does not address the control of process conditions.

[0009] Chinese patent document CN118185652A discloses a method for simultaneously producing mesophase pitch and COPNA resin from heavy oil. The thermal polymerization process of this method includes: nitrogen bubbling purging or vacuum distillation at a gas flow rate of 2 to 10 L / (min·Kg) under normal pressure and a temperature of 350°C to 450°C for 0.5 h to 24 h. In this reaction, the purpose of nitrogen bubbling or vacuum distillation is a conventional devolatilization process, and the control of process conditions is not involved.

[0010] In his paper "Research on the Formation of Volatile Matter in Coal Liquefaction Pitch Polymerization and Its Influence on the Properties of Mesophase Pitch" (Journal of Shijiazhuang Railway University (Natural Science Edition), March 2024, Vol. 37, No. 1), Liu Junqing discusses how the presence of volatile matter affects the softening point of mesophase pitch; the higher the volatile matter content, the lower the softening point. When the volatile matter content in pitch is low, the softening point of pitch increases significantly, which is detrimental to the processing performance of pitch. There is a difference in softening point between the upper and lower parts of the product. Reducing the difference in softening point between the upper and lower parts is beneficial for obtaining mesophase pitch with uniform properties. Lowering the volatile matter content in pitch can improve the uniformity of the softening point and also improve the uniformity of the mesophase morphology. The paper describes a purging process during the reaction to remove volatile matter from the reaction system in a timely manner, reducing the volatile matter content and facilitating the obtaining of mesophase pitch with uniform volatile matter distribution. However, continuous purging will cause the volatile matter in pitch to be removed from the reaction system too quickly, preventing sufficient reaction.

[0011] Existing research largely focuses on controlling the composition of raw materials to address the asynchronous nature of component diversification during thermal conversion, and on optimizing the composition of raw materials to regulate the polycondensation reaction activity and thus control the structure and properties of mesophase pitch. However, the complex composition of petroleum fractions makes precise control impossible, resulting in issues such as over-carbonization of some components and uneven product quality. Therefore, controlling the polycondensation process conditions based on the regulation of key components is crucial and is key to preparing high-performance spinning mesophase pitch. Current research on nitrogen purging processes focuses on removing small molecules generated by the polycondensation reaction and reducing the volatile content of the product. However, the presence of homogeneous structures in the product severely affects the uniformity of the mesophase pitch's properties. Current nitrogen purging methods fail to remove homogeneous structural components from the product, especially in the later stages of the reaction when the system viscosity increases. Even with a static settling process, homogeneous components are difficult to separate and remain trapped in the mesophase pitch, severely impacting its quality and performance. Summary of the Invention

[0012] This invention provides a method and apparatus for preparing spinnable mesophase pitch from aromatic heavy oil, which overcomes the shortcomings of the prior art. It can significantly improve the degree of polycondensation reaction, effectively remove potential components that are prone to forming isotropic structures, and obtain high-quality spinnable mesophase pitch from aromatic heavy oil without isotropic inclusions.

[0013] One of the technical solutions of this invention is achieved through the following measures: a method for preparing spinnable mesophase pitch from aromatic-rich heavy oil, obtained by the following method: The first step is to pretreat the aromatic-rich heavy oil by flash evaporation to obtain the heavy fraction. The second step involves thermally polycondensing the heavy fraction under a nitrogen atmosphere to obtain aromatic-rich heavy oil and prepare spinnable mesophase asphalt. In the thermal polycondensation reaction, the nitrogen purging flow rate is 10 L / (min·Kg) to 40 L / (min·Kg).

[0014] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: In the first step above, the heavy fraction has an initial boiling point >350℃.

[0015] In the first step above, the aromatic heavy oil contains >60% aromatics, <0.5% sulfur, <50μg / g ash, and <0.5% asphaltenes.

[0016] In the second step above, the heating rate in the thermal polycondensation reaction is 5℃ / min to 10℃ / min, the reaction temperature is 390℃ to 440℃, the pressure is 1MPa to 4MPa, the stirring speed is 300r / min to 500r / min, and the reaction time is 4h to 12h.

[0017] In the second step above, the mesophase content of the spinnable mesophase pitch prepared from the aromatic heavy oil is 98% to 100% under polarized light, the yield is 35% to 55%, the softening point is 280℃ to 310℃, and the H / C molar ratio is 0.4 to 0.6.

[0018] The second technical solution of the present invention is achieved through the following measures: an apparatus for preparing spinnable mesophase pitch from aromatic heavy oil includes a polycondensation reactor, a liquid product receiving tank, and a light component oil and gas absorption tank. The top inlet of the polycondensation reactor is fixedly connected to a feed pipeline and a nitrogen pipeline, respectively. A first processing pipeline is fixedly connected between the outlet of the polycondensation reactor and the inlet of the liquid product receiving tank. A second processing pipeline is fixedly connected between the outlet of the liquid product receiving tank and the inlet of the light component oil and gas absorption tank. A third processing pipeline is fixedly connected to the outlet of the light component oil and gas absorption tank.

[0019] The following are further optimizations and / or improvements to the second technical solution of the above invention: The above also includes a flash tank and a nitrogen storage tank. A feed pipeline is fixedly connected between the outlet of the flash tank and the inlet of the polycondensation reactor, and a nitrogen pipeline is fixedly connected between the nitrogen storage tank and the inlet of the polycondensation reactor.

[0020] A stirrer is also fixedly installed on the inner side of the upper part of the polycondensation reactor, a thermocouple thermometer is also fixedly installed on the inner side of the upper part of the polycondensation reactor, and a heating jacket is also provided on the outer side of the lower part of the polycondensation reactor.

[0021] A nitrogen flow meter is fixedly installed on the aforementioned third treatment pipeline.

[0022] A nitrogen flow regulating valve is fixedly installed on the nitrogen pipeline, a back pressure valve is fixedly installed on the second processing pipeline, and a valve is fixedly installed on the feed pipeline.

[0023] This invention relates to a method for preparing spinnable mesophase pitch from aromatic heavy oil. The method uses aromatic heavy oil as raw material and prepares it via a high-temperature, high-pressure direct thermal polycondensation process. By controlling the nitrogen purging flow rate during the reaction, the polycondensation reaction rate is regulated, and potential molecules forming isotropic structures are removed. This results in a high-quality spinnable mesophase pitch from aromatic heavy oil with a moderate degree of polycondensation and no isotropic inclusions. The mesophase content is above 98%, the yield is 35% to 55%, the softening point is 280℃ to 310℃, and the H / C molar ratio is 0.4 to 0.6. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of Embodiment 12 of the present invention.

[0025] Appendix Figure 1 The codes in the table are as follows: 1 is a polycondensation reactor, 2 is a liquid product receiving tank, 3 is a light component oil and gas absorption tank, 4 is a flash tank, 5 is a nitrogen storage tank, 6 is a feed pipeline, 7 is a nitrogen pipeline, 8 is a first processing pipeline, 9 is a second processing pipeline, 10 is a third processing pipeline, 11 is a stirrer, 12 is a thermocouple thermometer, 13 is a heating jacket, 14 is a nitrogen flow meter, 15 is a nitrogen flow regulating valve, 16 is a back pressure valve, and 17 is a valve.

[0026] Figure 2 A polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Example 6 of this invention.

[0027] Figure 3 A polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Example 7 of this invention.

[0028] Figure 4 A polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Example 8 of this invention.

[0029] Figure 5 A polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Example 9 of this invention.

[0030] Figure 6 The image is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Example 10 of this invention.

[0031] Figure 7 The image is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Example 11 of this invention.

[0032] Figure 8 This is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Comparative Example 1 of this invention.

[0033] Figure 9 This is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Comparative Example 2 of this invention.

[0034] Figure 10 This is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Comparative Example 3 of this invention.

[0035] Figure 11 This is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic-rich heavy oil prepared in Comparative Example 4 of this invention.

[0036] Figure 12 This is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic heavy oil prepared in Comparative Example 5 of this invention.

[0037] Figure 13 This is a polarizing microscope (PC) image of the preparation of spinnable mesophase pitch from the aromatic-rich heavy oil prepared in Comparative Example 6 of this invention. Detailed Implementation

[0038] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0039] In this invention, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 1 The orientation of the layout is determined by the direction of the map.

[0040] The present invention will be further described below with reference to embodiments: Example 1: A method for preparing spinnable mesophase pitch from aromatic-rich heavy oil, obtained by the following method: The first step is to pretreat the aromatic-rich heavy oil by flash evaporation to obtain the heavy fraction. The second step involves thermally polycondensing the heavy fraction under a nitrogen atmosphere to obtain aromatic-rich heavy oil and prepare spinnable mesophase asphalt. In the thermal polycondensation reaction, the nitrogen purging flow rate is 10 L / (min·Kg) to 40 L / (min·Kg).

[0041] In this invention, the thermal polycondensation reaction is a free radical reaction, which is extremely sensitive to the reaction temperature. In the early stage of the reaction, decomposition is the main reaction, resulting in the scission of alkyl or cycloalkyl side chains to form free radicals and release light component gases. In the later stage, condensation is the main reaction, gradually forming larger polycyclic aromatic hydrocarbon molecules until an intermediate phase is generated. The light component gases generated by cracking are retained in the reaction system under certain pressure, maintaining the low viscosity of the system and inhibiting the continued condensation of molecules with higher condensation reactivity. This provides a sufficient environment for the coalescence and growth of the intermediate phase. However, excessive light component gases remaining in the system reduce the condensation reactivity of the system and also hinder the formation and coalescence of the intermediate phase, affecting the content of the intermediate phase in the product. Meanwhile, because the small aromatic or cycloalkanes generated after chain cleavage are not easy to leave the reaction system and remain in the system for a long time, their condensation activity is low and they are difficult to participate in the rearrangement reaction of the mesophase structure. In the later stage, they are prone to forming out-of-plane disordered crosslinks with macromolecular free radicals, and finally forming macromolecules with isotropic structures in the product. Under polarized light, they appear as black spheres or ellipsoids. Since the density of this type of isotropic structure is close to that of the mesophase, it is also difficult to separate from the mesophase during the later standing process. Therefore, it is necessary to remove them during the reaction process.

[0042] Existing nitrogen purging processes can only remove a small portion of light components and are mostly used for devolatilization in the later stages of the reaction. They fail to remove the potential components that easily form isomorphic structures in the early stages of the reaction. This invention uses nitrogen purging at a flow rate of 10 L / (min·Kg) to 40 L / (min·Kg), effectively removing the potential components that easily form isomorphic structures. At the same time, as the nitrogen gas flows out, the vapor pressure of the light components above the liquid phase reaction system decreases. In order to generate more small molecules to maintain the vapor pressure of the light components, the thermal decomposition reaction of the system is promoted, more free radicals are generated, the condensation reaction is accelerated, the degree of condensation of the product is significantly deepened, the original required condensation reaction temperature and condensation time are reduced, and the over-carbonization of highly reactive molecules is avoided, which is conducive to the formation of a uniform carbonaceous mesophase.

[0043] Example 2: As an optimization of the above example, in the first step, the fraction with an initial boiling point > 350°C of the heavy fraction is included.

[0044] Example 3: As an optimization of the above example, in the first step, the aromatic heavy oil contains >60% aromatics, <0.5% sulfur, <50μg / g ash, and <0.5% asphaltenes.

[0045] Example 4: As an optimization of the above example, in the second step, the thermal polycondensation reaction is carried out at a heating rate of 5°C / min to 10°C / min, a reaction temperature of 390°C to 440°C, a pressure of 1MPa to 4MPa, a stirring speed of 300r / min to 500r / min, and a reaction time of 4h to 12h.

[0046] Example 5: As an optimization of the above example, in the second step, the mesophase content of the spinnable mesophase pitch prepared from the aromatic heavy oil is 98% to 100% under polarized light, the yield is 35% to 55%, the softening point is 280°C to 310°C, and the H / C molar ratio is 0.4 to 0.6.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the method for preparing spinnable mesophase pitch from aromatic heavy oil provided by the present invention uses nitrogen purging at a flow rate of 10 L / (min·Kg) to 40 L / (min·Kg) to effectively remove potential components that are prone to forming isotropic structures, significantly deepens the degree of polycondensation of the product, reduces the original required polycondensation reaction temperature and polycondensation time, avoids excessive carbonization of molecules with high polycondensation reaction activity, and is conducive to the formation of a carbonaceous mesophase with a uniform structure. Secondly, this invention breaks through the limitations in understanding the role of nitrogen purging in polycondensation reactions, demonstrating a significant impact on the degree of polycondensation under a certain purging flow rate. Furthermore, the method for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to this invention features a simple process flow and equipment, low preparation cost, controllable reaction conditions, and produces spinnable mesophase pitch with a low softening point and high mesophase content, making it easily industrial-scale.

[0048] Example 6: The spinnable mesophase pitch was prepared from the aromatic-rich heavy oil by the following method: The first step is to pump the aromatic-rich heavy oil into flash tank 4 for flash pretreatment to obtain a heavy fraction with an initial boiling point >350℃. The second step involves adding the recombinant fraction to a high-temperature, high-compression polycondensation reactor 1. After sealing, nitrogen gas is introduced to replace the residual air in the reactor 1. The pressure is increased to 1.0 MPa, and stirring and heating are started. The stirring rate is 300 r / min, and the temperature of the polycondensation reactor 1 is increased to the polycondensation reaction temperature of 400℃ at a rate of 5℃ / min. The pressure is maintained at 1.0 MPa. The nitrogen flow regulating valve 15 of the nitrogen storage tank 5 is adjusted to make the nitrogen purging flow rate (nitrogen flow meter 14) 10 L / (min·Kg). The reaction time is 11 h. After the reaction is completed, heating is stopped. When the internal and external temperatures of the polycondensation reactor 1 drop below 350℃, stirring is turned off. After natural cooling to room temperature, nitrogen purging is turned off, and the reactor is unloaded to obtain spinnable mesophase pitch prepared from aromatic heavy oil. The yield is calculated. The properties of the raw material aromatic heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 6 of this invention is shown in Figure 1. Figure 2 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 6 of this invention are shown in Table 2.

[0049] Example 7: The spinnable mesophase pitch was prepared from the aromatic-rich heavy oil by the following method: The first step is to pump the aromatic-rich heavy oil into flash tank 4 for flash pretreatment to obtain a heavy fraction with an initial boiling point >350℃. The second step involves adding the recombinant fraction to a high-temperature, high-compression polycondensation reactor 1. After sealing, nitrogen gas is introduced to replace the residual air in the reactor 1. The pressure is increased to 4.0 MPa, and stirring and heating are started. The stirring rate is 500 r / min, and the temperature in the reactor 1 is increased to the polycondensation reaction temperature of 440°C at a rate of 8°C / min. The pressure is maintained at 4.0 MPa. The nitrogen flow regulating valve 15 of the nitrogen storage tank 5 is adjusted to make the nitrogen purging flow rate (nitrogen flow meter 14) 20 L / (min·Kg). The reaction time is 4 hours. After the reaction is completed, heating is stopped. When the internal and external temperatures of the polycondensation reactor 1 drop below 350°C, stirring is turned off. After natural cooling to room temperature, nitrogen purging is turned off, and the reactor is unloaded to obtain spinnable mesophase pitch prepared from aromatic heavy oil. The yield is calculated. The properties of the raw material aromatic heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 7 of this invention is shown in the figure. Figure 3 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 7 of this invention are shown in Table 2.

[0050] Example 8: The spinnable mesophase pitch was prepared from the aromatic-rich heavy oil by the following method: The first step is to pump the aromatic-rich heavy oil into flash tank 4 for flash pretreatment to obtain a heavy fraction with an initial boiling point >350℃. The second step involves adding the recombinant fraction to a high-temperature, high-compression polycondensation reactor 1. After sealing, nitrogen gas is introduced to replace the residual air in the reactor 1. The pressure is increased to 2.0 MPa, and stirring and heating are started. The stirring rate is 400 r / min, and the temperature in the reactor 1 is increased to the polycondensation reaction temperature of 390°C at a rate of 10°C / min. The pressure is maintained at 2.0 MPa. The nitrogen flow regulating valve 15 of the nitrogen storage tank 5 is adjusted to make the nitrogen purging flow rate (nitrogen flow meter 14) 30 L / (min·Kg). The reaction time is 10 h. After the reaction is completed, heating is stopped. When the internal and external temperatures of the polycondensation reactor 1 drop below 350°C, stirring is turned off. After natural cooling to room temperature, nitrogen purging is turned off, and the reactor is unloaded to obtain spinnable mesophase pitch prepared from aromatic heavy oil. The yield is calculated. The properties of the raw material aromatic heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 8 of this invention is shown in Figure 1. Figure 4 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 8 of this invention are shown in Table 2.

[0051] Example 9: The spinnable mesophase pitch was prepared from the aromatic-rich heavy oil by the following method: The first step is to pump the aromatic-rich heavy oil into flash tank 4 for flash pretreatment to obtain a heavy fraction with an initial boiling point >350℃. The second step involves adding the recombinant fraction to a high-temperature, high-compression polycondensation reactor 1. After sealing, nitrogen gas is introduced to replace the residual air in the reactor 1. The pressure is increased to 3.0 MPa, and stirring and heating are started. The stirring rate is 400 r / min, and the temperature in the reactor 1 is increased to the polycondensation reaction temperature of 420°C at a rate of 6°C / min. The pressure is maintained at 3.0 MPa. The nitrogen flow regulating valve 15 of the nitrogen storage tank 5 is adjusted to make the nitrogen purging flow rate (nitrogen flow meter 14) 10 L / (min·Kg). The reaction time is 12 h. After the reaction is completed, heating is stopped. When the internal and external temperatures of the polycondensation reactor 1 drop below 350°C, stirring is turned off. After natural cooling to room temperature, nitrogen purging is turned off, and the reactor is unloaded to obtain spinnable mesophase pitch prepared from aromatic heavy oil. The yield is calculated. The properties of the raw material aromatic heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 9 of this invention is shown in Figure 1. Figure 5 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 9 of this invention are shown in Table 2.

[0052] Example 10: The spinnable mesophase pitch was prepared from the aromatic-rich heavy oil by the following method: The first step is to pump the aromatic-rich heavy oil into flash tank 4 for flash pretreatment to obtain a heavy fraction with an initial boiling point >350℃. The second step involves adding the recombinant fraction to a high-temperature, high-compression polycondensation reactor 1. After sealing, nitrogen gas is introduced to replace the residual air in the reactor 1. The pressure is increased to 2.0 MPa, and stirring and heating are started. The stirring rate is 300 r / min, and the temperature in the reactor 1 is increased to the polycondensation reaction temperature of 400°C at a rate of 5°C / min. The pressure is maintained at 2.0 MPa. The nitrogen flow regulating valve 15 of the nitrogen storage tank 5 is adjusted to make the nitrogen purging flow rate (nitrogen flow meter 14) 30 L / (min·Kg). The reaction time is 6 hours. After the reaction is completed, heating is stopped. When the internal and external temperatures of the polycondensation reactor 1 drop below 350°C, stirring is turned off. After natural cooling to room temperature, nitrogen purging is turned off, and the reactor is unloaded to obtain spinnable mesophase pitch prepared from aromatic heavy oil. The yield is calculated. The properties of the raw material aromatic heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 10 of this invention is shown in Figure 1. Figure 6 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 10 of this invention are shown in Table 2.

[0053] Example 11: The spinnable mesophase pitch was prepared from the aromatic-rich heavy oil by the following method: The first step is to pump the aromatic-rich heavy oil into flash tank 4 for flash pretreatment to obtain a heavy fraction with an initial boiling point >350℃. The second step involves adding the recombinant fraction to a high-temperature, high-compression polycondensation reactor 1. After sealing, nitrogen gas is introduced to replace the residual air in the reactor 1. The pressure is increased to 1.0 MPa, and stirring and heating are started. The stirring rate is 300 r / min, and the temperature of the polycondensation reactor 1 is increased to the polycondensation reaction temperature of 390°C at a rate of 7°C / min. The pressure is maintained at 1.0 MPa. The nitrogen flow regulating valve 15 of the nitrogen storage tank 5 is adjusted to make the nitrogen purging flow rate (nitrogen flow meter 14) 40 L / (min·Kg). The reaction time is 5 h. After the reaction is completed, heating is stopped. When the internal and external temperatures of the polycondensation reactor 1 drop below 350°C, stirring is turned off. After natural cooling to room temperature, nitrogen purging is turned off, and the reactor is unloaded to obtain spinnable mesophase pitch prepared from aromatic heavy oil. The yield is calculated. The properties of the raw material aromatic heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 11 of this invention is shown in Figure 1. Figure 7 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil in Example 11 of this invention are shown in Table 2.

[0054] Comparative Example 1: This mesophase pitch differs from Example 6 of the present invention in that the nitrogen purging flow rate (nitrogen flow meter 14) is 5 L / (min·Kg), while the remaining steps are the same as in Example 6. The properties of the aromatic-rich heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic-rich heavy oil of Comparative Example 1 of the present invention is shown below. Figure 8 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil of Comparative Example 1 of this invention are shown in Table 2.

[0055] Comparative Example 2: This mesophase pitch differs from Example 7 of the present invention in that the nitrogen purging flow rate (nitrogen flow meter 14) is 2 L / (min·Kg), while the remaining steps are the same as in Example 7. The properties of the aromatic-rich heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic-rich heavy oil in Comparative Example 2 of the present invention is shown below. Figure 9 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil of Comparative Example 2 of this invention are shown in Table 2.

[0056] Comparative Example 3: This mesophase pitch differs from Example 8 of the present invention in that the nitrogen purging flow rate (nitrogen flow meter 14) is 1 L / (min·Kg), while the remaining steps are the same as in Example 8. The properties of the aromatic-rich heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic-rich heavy oil in Comparative Example 3 of the present invention is shown below. Figure 10 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil of Comparative Example 3 of this invention are shown in Table 2.

[0057] Comparative Example 4: This mesophase pitch differs from Example 9 of the present invention in that the nitrogen purging flow rate (nitrogen flow meter 14) is 2 L / (min·Kg), the reaction time is 16 h, and the remaining steps are the same as in Example 9. The properties of the aromatic-rich heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic-rich heavy oil in Comparative Example 4 of the present invention is shown below. Figure 11 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil of Comparative Example 4 of this invention are shown in Table 2.

[0058] Comparative Example 5: This mesophase pitch differs from Example 9 of the present invention in that the polycondensation reaction temperature is 430°C, the nitrogen purging flow rate (nitrogen flow meter 14) is 2 L / (min·Kg), and the remaining steps are the same as in Example 9. The properties of the aromatic-rich heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic-rich heavy oil of Comparative Example 5 of the present invention is shown below. Figure 12 As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil of Comparative Example 5 of this invention are shown in Table 2.

[0059] Comparative Example 6: This mesophase pitch differs from Example 11 of the present invention in that the nitrogen purging flow rate (nitrogen flow meter 14) is 8 L / (min·Kg), while the remaining steps are the same as in Example 11. The properties of the aromatic-rich heavy oil are shown in Table 1. The polarized light microscope (PC) image of the spinnable mesophase pitch prepared from the aromatic-rich heavy oil of Comparative Example 6 of the present invention is shown below. Figure 13As shown in Table 2, the properties of the spinnable mesophase pitch prepared from the aromatic heavy oil of Comparative Example 6 of this invention are shown in Table 2.

[0060] The properties of the spinnable mesophase pitch prepared from aromatic heavy oil in Examples 6 to 11 of this invention, and the mesophase pitch prepared in Comparative Examples 1 to 6, are shown in Table 2. Considering the preparation methods of Comparative Examples 1 and 6, Comparative Examples 2 and 7, Comparative Examples 3 and 8, and Comparative Examples 6 and 11, the preparation methods in Comparative Examples 1, 2, 3, and 6 are identical to those in Examples 6, 7, 8, and 11, except for the nitrogen purging flow rate. The data in Table 2 show that when the nitrogen purging flow rate is below 10 L / (min·Kg), the yield of the condensation product increases, the mesophase content decreases, the softening point decreases, and the H / C ratio increases, indicating a decrease in the degree of condensation of the condensation product. Polarized light microscopy images show an increase in the content of isotropic structures in the product. However, when the nitrogen purging flow rate increases to above 10 L / (min·Kg), the degree of condensation reaction is significantly improved, effectively removing potential components that easily generate isotropic structures, reducing the content of isotropic structures in the product, and improving the uniformity of the product structure.

[0061] Comparative Examples 4 and 5 were based on Example 9, with reduced nitrogen purging flow rate, extended reaction time, and increased polycondensation temperature, respectively. As shown in Table 2, the degree of polycondensation was similar. However, the mesophase content and softening point of the products from Comparative Examples 3 and 4 were relatively low. This indicates that while increasing the polycondensation temperature or extending the polycondensation time can achieve a similar degree of polycondensation, the reduced nitrogen purging flow rate leads to decreased product homogeneity and over-carbonization of some components.

[0062] Therefore, increasing the nitrogen purging flow rate can reduce the original required condensation reaction temperature and condensation time to achieve the same degree of condensation, avoiding excessive carbonization of molecules with high condensation reaction activity, and promoting the formation of a carbonaceous mesophase with a uniform structure.

[0063] Example 12: As Figure 1 As shown, the apparatus for preparing spinnable mesophase pitch from aromatic heavy oil includes a polycondensation reactor 1, a liquid product receiving tank 2, and a light component oil and gas absorption tank 3. The top inlet of the polycondensation reactor 1 is fixedly connected to a feed pipeline 6 and a nitrogen pipeline 7, respectively. The outlet of the polycondensation reactor 1 is fixedly connected to the inlet of the liquid product receiving tank 2 via a first processing pipeline 8. The outlet of the liquid product receiving tank 2 is fixedly connected to the inlet of the light component oil and gas absorption tank 3 via a second processing pipeline 9. The outlet of the light component oil and gas absorption tank 3 is fixedly connected to a third processing pipeline 10.

[0064] This device sends the heavy fraction of the raw material and nitrogen to the polycondensation reactor 1 for polycondensation reaction under certain conditions. During the reaction, the by-products (gasoline, diesel, wax oil) and light component oil gas produced by the polycondensation reaction are sent to the liquid product receiving tank 2 for storage through the first processing pipeline 8. The light component oil gas in the upper part of the liquid product receiving tank 2 is sent to the light component oil gas absorption tank 3 through the second processing pipeline 9 and absorbed by the solvent (water) in the light component oil gas absorption tank 3. After the reaction is completed, the solid in the polycondensation reactor 1 is the spinnable mesophase asphalt prepared from the aromatic heavy oil.

[0065] Example 13: As Figure 1 As shown, as an optimization of the above embodiment, it also includes a flash tank 4 and a nitrogen storage tank 5. A feed pipeline 6 is fixedly connected between the outlet of the flash tank 4 and the inlet of the polycondensation reactor 1, and a nitrogen pipeline 7 is fixedly connected between the nitrogen storage tank 5 and the inlet of the polycondensation reactor 1.

[0066] Example 14: As Figure 1 As shown, as an optimization of the above embodiment, a stirrer 11 is also fixedly installed on the inner side of the upper part of the polycondensation reactor 1, a thermocouple thermometer 12 is also fixedly installed on the inner side of the upper part of the polycondensation reactor 1, and a heating jacket 13 is also provided on the outer side of the lower part of the polycondensation reactor 1. During use, the heating jacket 13 is used to heat the polycondensation reactor 1, and the temperature of the polycondensation reaction is controlled by the thermocouple thermometer 12.

[0067] Example 15: As Figure 1 As shown, as an optimization of the above embodiment, a nitrogen flow meter 14 is fixedly installed on the third processing pipeline 10. This configuration allows for real-time monitoring of the nitrogen purging flow rate in the device.

[0068] Example 16: As Figure 1 As shown, as an optimization of the above embodiment, a nitrogen flow regulating valve 15 is fixedly installed on the nitrogen pipeline 7, a back pressure valve 16 is fixedly installed on the second processing pipeline 9, and a valve 17 is fixedly installed on the feed pipeline 6. With this arrangement, the nitrogen flow rate is controlled by the nitrogen flow regulating valve 15, and the pressure of the polymerization reaction is stabilized by the back pressure valve 16.

[0069] As required, the polycondensation reactor 1, flash tank 4, thermocouple thermometer 12, heating jacket 13, and nitrogen flow meter 14 in this device are all existing and well-known equipment and instruments.

[0070] The process of using the apparatus for implementing the method of preparing spinnable mesophase pitch from aromatic heavy oil of the present invention is as follows: First, the aromatic-rich heavy oil is sent to flash tank 4 for flash pretreatment to obtain the heavy fraction. Then, the recombinant fraction is fed into the polycondensation reactor 1 through the feed line 6. Nitrogen in the nitrogen storage tank 5 is fed into the polycondensation reactor 1 through the nitrogen line 7. After the polycondensation reactor 1 is raised to the reaction pressure, the stirrer 11 is turned on for stirring and the heating jacket 13 is turned on for heating. The stirring rate and polycondensation reaction temperature are controlled. The nitrogen flow regulating valve 15 on the nitrogen line 7 is adjusted. At the same time, the nitrogen flow meter 14 on the third processing line 10 is monitored to control the nitrogen purging flow range of the reaction. Finally, after the reaction is complete, stop heating with heating jacket 13. When the temperature inside and outside the polycondensation reactor 1 drops below 350°C, turn off stirrer 11 and stop stirring. After naturally cooling to room temperature, turn off nitrogen flow regulating valve 15 and stop nitrogen purging. The solid in polycondensation reactor 1 is the spinnable mesophase pitch prepared from aromatic heavy oil.

[0071] In summary, this invention uses aromatic-rich heavy oil as raw material to prepare mesophase pitch via high-temperature and high-pressure direct thermal polycondensation. Nitrogen purging significantly affects the degree of polycondensation, lowers the polycondensation temperature, shortens the reaction time, avoids the formation of some over-carbonized products, and improves preparation efficiency and product uniformity. It features a simple process and equipment, low preparation cost, controllable reaction conditions, and the prepared spinnable mesophase pitch from aromatic-rich heavy oil has a low softening point, high mesophase content, and is easy to industrialize. Specifically, the mesophase content is over 98%, the yield is 35% to 55%, the softening point is 280℃ to 310℃, and the H / C molar ratio is 0.4 to 0.6.

[0072] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for preparing spinnable mesophase pitch from aromatic-rich heavy oil, characterized in that... Obtained using the following method: The first step is to pretreat the aromatic-rich heavy oil by flash evaporation to obtain the heavy fraction. The second step involves thermally polycondensing the heavy fraction under a nitrogen atmosphere to obtain aromatic-rich heavy oil for preparing spinnable mesophase asphalt. In the thermal polycondensation reaction, the nitrogen purging flow rate is 10 L / min to 40 L / min per kilogram of heavy fraction.

2. The method for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 1, characterized in that... In the first step, the fraction with an initial boiling point >350℃ is the heavy fraction.

3. The method for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 1 or 2, characterized in that... In the first step, the aromatic heavy oil contains >60% aromatics, <0.5% sulfur, <50μg / g ash, and <0.5% asphaltene.

4. The method for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 1, 2, or 3, characterized in that... In the second step, during the thermal polycondensation reaction, the heating rate is 5℃ / min to 10℃ / min, the reaction temperature is 390℃ to 440℃, the pressure is 1MPa to 4MPa, the stirring speed is 300r / min to 500r / min, and the reaction time is 4h to 12h.

5. The method for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 1, 2, 3, or 4, characterized in that... In the second step, the spinnable mesophase pitch prepared from aromatic heavy oil has a mesophase content of 98% to 100% under polarized light, a yield of 35% to 55%, a softening point of 280℃ to 310℃, and an H / C molar ratio of 0.4 to 0.

6.

6. An apparatus for implementing a method for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to any one of claims 1 to 5, characterized in that... It includes a polycondensation reactor, a liquid product receiving tank, and a light component oil and gas absorption tank. The top inlet of the polycondensation reactor is fixedly connected to a feed pipeline and a nitrogen pipeline. The outlet of the polycondensation reactor is fixedly connected to the inlet of the liquid product receiving tank, the outlet of the liquid product receiving tank is fixedly connected to the inlet of the light component oil and gas absorption tank, and the outlet of the light component oil and gas absorption tank is fixedly connected to a third processing pipeline.

7. The apparatus for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 6, characterized in that... It also includes a flash tank and a nitrogen storage tank. The outlet of the flash tank is fixedly connected to the inlet of the polycondensation reactor by a feed pipeline, and the nitrogen storage tank is fixedly connected to the inlet of the polycondensation reactor by a nitrogen pipeline.

8. The apparatus for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 6 or 7, characterized in that... A stirrer is fixedly installed on the inner side of the upper part of the polycondensation reactor, a thermocouple thermometer is fixedly installed on the inner side of the upper part of the polycondensation reactor, and a heating jacket is provided on the outer side of the lower part of the polycondensation reactor.

9. The apparatus for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 6, 7, or 8, characterized in that... A nitrogen flow meter is fixedly installed on the third treatment pipeline.

10. The apparatus for preparing spinnable mesophase pitch from aromatic-rich heavy oil according to claim 6, 7, 8, or 9, characterized in that... A nitrogen flow regulating valve is fixedly installed on the nitrogen pipeline, a back pressure valve is fixedly installed on the second processing pipeline, and a valve is fixedly installed on the feed pipeline.

Images