Spinnable mesophase pitch and preparation method thereof

Abstract

The invention relates to the technical field of mesophase pitch preparation, in particular to spinnable mesophase pitch and a preparation method thereof.The spinnable mesophase pitch is obtained through the following steps that firstly, aromatic hydrocarbon-rich raw material oil and an extraction solvent are extracted according to the proportion, then extracted oil and raffinate oil are obtained after standing sedimentation and separation, and then the spinnable mesophase pitch is obtained; the method comprises the following steps: filtering raffinate oil, carrying out atmospheric and vacuum distillation to obtain heavy raffinate oil, heating and distilling the raffinate oil to obtain refined raffinate oil, and finally, mixing the refined raffinate oil and the heavy raffinate oil in proportion, and carrying out thermal polycondensation reaction to obtain the product. The preparation method of spinnable mesophase pitch provided by the invention can deeply and accurately regulate and control the structure, composition and molecular weight distribution of aromatic hydrocarbon-rich raw oil, and has the characteristics of simple process flow and equipment, low preparation cost, controllable reaction conditions, easy realization of industrial production, high yield and the like. The prepared spinnable mesophase pitch has the characteristics of low softening point and high mesophase content.

Description

Technical Field

[0001] The invention relates to the technical field of mesophase asphalt preparation, in particular to a spinnable mesophase asphalt and a preparation method thereof. Background Art

[0002] Mesophase pitch is a macromolecular condensed ring compound obtained by thermal cracking and thermal polycondensation of petroleum pitch, coal pitch, or aromatic compounds under certain pressure and temperature. Due to its excellent properties such as high order and easy graphitization, it can be used as an excellent precursor for advanced carbon materials such as mesophase pitch-based carbon fiber, needle coke, and C / C composite materials.

[0003] Mesophase pitch refers to pitch containing mesophase structure, but only spinnable mesophase pitch can produce high-performance mesophase pitch-based carbon fiber. Therefore, the quality requirements for spinnable mesophase pitch are higher. Specifically, first, a high mesophase content is required, usually more than 90%, or even 100%. High mesophase content is the guarantee that the system can obtain a high degree of orientation. High mesophase content means that the condensed aromatic hydrocarbon molecules need to reach a certain molecular weight level, but it is necessary to prevent the molecular weight from being too large and causing loss of spinnability; second, the mesophase must have a good morphology, which is reflected in the test results. It is required to be a wide-area streamlined shape under the hot stage polarizing microscope. Such a mesophase reflects that the system has good fluidity and a relatively narrow molecular weight distribution; third, the softening point is usually required to reach 230℃ to 280℃. If the softening point is too high, the difficulty of spinning will increase. When the spinning temperature exceeds 380℃, the system is prone to decomposition, affecting the product quality; if the softening point is too low, although spinning is easy, it will cause difficulties for subsequent pre-oxidation, and the oriented structure formed is relatively easy to be destroyed. Fourth, the content of heteroatoms and ash should be low. Ash content will make the system difficult to spin, and the strength and thermal conductivity of the obtained carbon fiber will deteriorate. Heteroatoms such as sulfur will escape during fiber graphitization and cause defects, which will also affect product performance.

[0004] Research has found that in order to obtain high-quality spinnable mesophase asphalt, the composition and structure of the appropriate raw material oil are very critical. It is generally believed that raw materials rich in 3 to 5-ring aromatics are more conducive to obtaining excellent mesophase structures, but they cannot be used as a criterion for determining high-quality raw materials. They are also related to the composition of other structures in the raw materials and the structure of substituents on the aromatic rings, as well as factors such as ash content and heteroatom content in the raw materials. The presence of saturated components in the raw materials is not conducive to the formation of an ordered structure of the mesophase. During thermal cracking, they capture active hydrogen from colloids and asphaltene, promote coke formation, and are not conducive to the formation of an ordered structure of the mesophase. The size of the aromatic molecules in the raw materials and the planarity of the aromatics during the formation process affect the internal structure and physicochemical properties of the mesophase. The planar structure of the aromatic molecules is related to the number of substituents. With the increase of side chain substituents, the non-planar type will be higher, resulting in an increased difficulty in the formation of macromolecular aromatic planar sheets and an increase in the isotropic structure in the product. The light components with a certain aromaticity and the light components of cycloalkanes in the raw materials can serve as effective solvents and hydrogen donors, limiting the excessive condensation of macromolecules and enabling the reaction to obtain planar aromatic molecules with a moderate relative molecular weight. The activity of the reaction system is maintained within a certain range, allowing the mesophase globules to grow evenly, which is conducive to the formation of a uniform, wide-area structured mesophase.

[0005] The Chinese patent document with the publication number CN107189802A discloses a method for preparing mesophase asphalt by hydrogenation reforming / segmented thermal polycondensation of FCC oil slurry, specifically, after the FCC oil slurry is vacuum distilled and cut into fractions, a petroleum asphalt with a softening point of 110°C to 180°C is obtained after heat treatment, 1% to 15% of hydrogen supply reagent tetralin is added to the petroleum asphalt, and hydrogenation treatment is carried out under the reaction condition of an initial pressure of 5MPa, and the obtained hydrogenated asphalt continues to react to obtain high-quality mesophase asphalt. Since the hydrogen supply reagent used in this method is tetralin, which has a low boiling point, in order to achieve a better hydrogenation treatment effect, the initial pressure needs to reach 5MPa, and the pressure is even greater after the temperature is raised, which has strict requirements on equipment conditions and has operational safety problems. Moreover, when the hydrogenated asphalt continues to be thermally polymerized at 400°C to 480°C, pyrolysis will proceed simultaneously, and a certain amount of light components will be generated. The method does not make a treatment plan for this, and the obtained mesophase asphalt is prone to excessive volatiles during spinning.

[0006] The Chinese patent document with publication number CN110041952A discloses a mesophase pitch and a preparation method thereof, which specifically uses a heavy product obtained by thermal catalysis of lignite as a raw material, and obtains the mesophase pitch through thermal polycondensation, vacuum distillation, hydrogenation reaction, flash evaporation and thermal sensitization. This method imposes a large range of restrictions on the raw materials, and the mesophase content level of the obtained product is not high, which does not meet the application requirements of high-performance pitch-based carbon fibers.

[0007] The Chinese patent document with publication number CN110776943A discloses a method for preparing a spinnable mesophase pitch, which specifically comprises the following steps: crushing a high softening point petroleum pitch, performing heat extraction, filtering, and obtaining a purified petroleum pitch; mixing the purified petroleum pitch with octahydrophenanthrene or a hydrogen-donating agent containing octahydrophenanthrene, and then performing a thermal polycondensation reaction; after the thermal polycondensation reaction is completed, the pressure is reduced, and the mixture is stirred and purged at 370°C to 420°C to obtain the mesophase pitch. However, the mass content of octahydrophenanthrene used in this method is greater than 50%, resulting in a high preparation cost, which limits its promotion and application.

[0008] The raw oils rich in aromatic components such as petroleum asphalt and coal tar pitch for preparing mesophase asphalt often have a wide molecular weight distribution range and high asphaltene and heteroatom contents. The raw materials need to be refined before the reaction. Solvent extraction refining is a commonly used and effective method for enriching aromatics. However, for high-quality cycloalkane-rich aromatic raw oils, solvent extraction refining enriches aromatics while leaving cycloalkanes in the raw materials in the raffinate, destroying the hydrogen supply advantage of cycloalkanes in the raw materials. Therefore, the existing traditional single treatment process is difficult to meet the requirements. Summary of the invention

[0009] The present invention provides a spinnable mesophase pitch and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art. The spinnable mesophase pitch prepared by the invention has the characteristics of low softening point and high mesophase content.

[0010] One of the technical solutions of the present invention is achieved by the following measures: a spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the aromatics-rich feedstock oil and the extraction solvent in proportion, and then standing, settling and separating to obtain an extraction oil and a raffinate oil; S2, filtering the raffinate oil in a heated state to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain heavy raffinate oil; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining refined extracted oil; S4, mixing the refined extraction oil and the heavy extraction raffinate oil in proportion as co-carbonization feedstock oil, placing the co-carbonization feedstock oil in a nitrogen atmosphere, and then subjecting the co-carbonization feedstock oil to a thermal polycondensation reaction to obtain a spinnable mesophase pitch.

[0011] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The aromatics-rich feedstock oil is one or more of cycloalkyl catalytic cracking slurry, cycloalkyl catalytic cracking cycle oil, cycloalkyl coker wax oil and cycloalkyl vacuum distillate oil.

[0012] The extraction solvent is one or more of furfural, N,N-dimethylformamide and N-methylpyrrolidone.

[0013] In the above step S1, the weight ratio of the aromatics-rich feedstock oil to the extraction solvent is 1:(1 to 4).

[0014] In the above step S4, the weight ratio of the refined extract oil to the heavy raffinate oil is 10:(1 to 3).

[0015] In the above step S1, the extraction temperature is 55°C to 65°C, the extraction time is 30min to 40min, and the static sedimentation time is 30min to 40min.

[0016] In the above step S2, the heating temperature is 80°C to 150°C, and a ceramic membrane with a pore size of 20nm to 150nm is used as a filter membrane for filtration.

[0017] In the above step S4, during the thermal polycondensation reaction, the reaction temperature is 400° C. to 450° C., the reaction pressure is 0.1 MPa to 4.0 MPa, and the reaction time is 4 h to 10 h.

[0018] The heavy raffinate has an initial distillation point greater than 400° C., an ash content of 0 μg / g to 10 μg / g, and a cycloalkane content of 70% to 85%.

[0019] The above-mentioned refined extraction oil has an aromatic content of 50% to 80% and an ash content of 0μg / g to 5μg / g.

[0020] The softening point of the spinnable mesophase pitch is 230° C. to 290° C., the mesophase content is 90.0% to 99.5%, and the H / C molar ratio is 0.55 to 0.65.

[0021] The second technical solution of the present invention is achieved by the following measures: A method for preparing a spinnable mesophase pitch is carried out as follows: S1, stirring and extracting the aromatics-rich feedstock oil and the extraction solvent in proportion, and then standing, settling and separating to obtain an extraction oil and a raffinate oil; S2, filtering the raffinate oil in a heated state to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain heavy raffinate oil; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining refined extracted oil; S4, mixing the refined extraction oil and the heavy raffinate oil in proportion as co-carbonization feedstock oil, and subjecting the co-carbonization feedstock oil to a thermal polycondensation reaction to obtain a spinnable mesophase pitch.

[0022] The method for preparing the spinnable mesophase asphalt provided by the present invention can deeply and accurately control the structure, composition and molecular weight distribution of the aromatic-rich feedstock oil, has the advantages of simple process flow, low preparation cost, controllable reaction conditions, and easy industrial production. The prepared spinnable mesophase asphalt has the characteristics of low softening point and high mesophase content. DETAILED DESCRIPTION

[0023] The present invention is not limited by the following embodiments, and specific implementation methods can be determined according to the technical scheme of the present invention and actual conditions. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art; the percentages in the present invention are all mass percentages unless otherwise specified.

[0024] The present invention will be further described below in conjunction with embodiments: Example 1: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the aromatics-rich feedstock oil and the extraction solvent in proportion, and then standing, settling and separating to obtain an extraction oil and a raffinate oil; S2, filtering the raffinate oil in a heated state to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain heavy raffinate oil; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining refined extracted oil; S4, mixing the refined extraction oil and the heavy raffinate oil in proportion as co-carbonization feedstock oil, and subjecting the co-carbonization feedstock oil to a thermal polycondensation reaction to obtain a spinnable mesophase pitch.

[0025] Example 2: As an optimization of the above example, the aromatics-rich feedstock oil is one or more of cycloalkyl catalytic cracking slurry oil, cycloalkyl catalytic cracking cycle oil, cycloalkyl coker wax oil and cycloalkyl vacuum distillate oil.

[0026] Example 3: As an optimization of the above example, the extraction solvent is one or more of furfural, N,N-dimethylformamide and N-methylpyrrolidone.

[0027] Example 4: As an optimization of the above example, in step S1, the weight ratio of the aromatics-rich feedstock oil to the extraction solvent is 1:(1 to 4).

[0028] Example 5: As an optimization of the above example, in step S4, the weight ratio of the refined extract oil to the heavy raffinate oil is 10:(1 to 3).

[0029] Example 6: As an optimization of the above example, in step S1, the extraction temperature is 55°C to 65°C, the extraction time is 30min to 40min, and the standing sedimentation time is 30min to 40min.

[0030] Example 7: As an optimization of the above example, in step S2, the heating temperature is 80°C to 150°C, and a ceramic membrane with a pore size of 20nm to 150nm is used as a filter membrane for filtration.

[0031] Example 8: As an optimization of the above example, in step S4, during the thermal polycondensation reaction, the reaction temperature is 400°C to 450°C, the reaction pressure is 0.1MPa to 4.0MPa, and the reaction time is 4h to 10h.

[0032] Example 9: As an optimization of the above example, the initial boiling point of the heavy raffinate is greater than 400° C., the ash content is 0 μg / g to 10 μg / g, and the cycloalkane content is 70% to 85%.

[0033] Example 10: As an optimization of the above example, the aromatic content of the refined extraction oil is 50% to 80%, and the ash content is 0 μg / g to 5 μg / g.

[0034] Example 11: As an optimization of the above example, the softening point of the spinnable mesophase pitch is 230°C to 290°C, the mesophase content is 90.0% to 99.5%, and the H / C molar ratio is 0.55 to 0.65.

[0035] In step S1 of the present invention, the extraction solvent has a strong solubility for heavy aromatic hydrocarbons with multiple rings and short side chains, and a weak solubility for hydrocarbons with few rings and long side chains. Therefore, the enrichment of aromatic hydrocarbons is achieved in the extracted oil, while the alkanes and cycloalkanes with long side chains are concentrated in the raffinate oil. At the same time, during the solvent extraction and refining process, the powder impurities in the raw oil are enriched in the raffinate oil. Due to its low viscosity, it is easy to remove by filtering in a heated state.

[0036] In step S2 of the present invention, the light components in the raffinate oil are evaporated to obtain heavy raffinate oil, and the cycloalkane components in the raffinate oil are enriched. Since cycloalkanes can be used as effective extraction solvents and hydrogen donors, the excessive condensation of macromolecules is limited during the formation of the intermediate phase, which is beneficial to the growth of the intermediate phase. However, they are enriched in the raffinate oil during the solvent extraction and refining process. Therefore, this part of the cycloalkanes cannot be effectively utilized. The present invention enriches the cycloalkanes and blends them into the refined extraction oil, providing a hydrogen donor for the intermediate phase asphalt reaction, achieving deep and precise control of the structure, composition and molecular weight distribution of the raw oil, and is beneficial to the preparation of a spinnable intermediate phase asphalt with excellent performance.

[0037] Compared with the existing technology, the present invention has the following beneficial effects: First, the spinnable mesophase pitch of the present invention does not use any solid catalyst in the whole process, does not introduce other solid impurities, has a low ash content, and does not introduce highly corrosive liquid or gas catalysts, so the process is relatively easy to industrialize; Second, the spinnable mesophase asphalt of the present invention, in view of the characteristics of the aromatic-rich feedstock oil (cycloalkane aromatic-rich fraction oil), effectively enriches the cycloalkane components in the raffinate oil by fraction separation, and the cycloalkane components are effectively utilized to provide a hydrogen donor for the mesophase asphalt reaction; Thirdly, the spinnable mesophase asphalt of the present invention can adjust the structure, composition and molecular weight distribution of the raw oil by adjusting the ratio of the refined extraction oil to the heavy raffinate oil, and prepare a spinnable mesophase asphalt with a softening point of 230°C to 290°C, a mesophase content of 90.0% to 99.5%, a high H / C molar ratio and good spinnability; Fourthly, the spinnable mesophase asphalt of the present invention has a simple process flow, fully utilizing the resource advantage of aromatic-rich feedstock oil (cycloalkyl aromatic-rich fraction oil), has low preparation cost, strong raw material adaptability, can realize flexible regulation of the hydrocarbon composition of aromatic-rich feedstock oil, and is easy to promote and realize industrialization.

[0038] Embodiment 12: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting cycloalkyl catalytic cracking cycle oil and furfural in a weight ratio of 1:1 at 60° C. for 30 minutes, and then standing and settling for 30 minutes to 40 minutes to separate extract oil and raffinate oil; S2, filtering the raffinate oil at 80°C using a ceramic membrane with a pore size of 20 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 0 μg / g, and a cycloalkane content of 83%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 78% and an ash content of 0 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:1 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 4MPa, and after a thermal polycondensation reaction at a temperature of 420°C for 6 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 280°C, an mesophase content of 98.5%, and an H / C molar ratio of 0.60.

[0039] Embodiment 13: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting cycloalkyl catalytic cracking oil slurry and furfural in a weight ratio of 1:2 at 65° C. for 35 minutes, and then standing and settling for 35 minutes to separate extract oil and raffinate oil; S2, filtering the raffinate oil at 150°C using a ceramic membrane with a pore size of 50 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 10 μg / g, and a cycloalkane content of 81%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 76% and an ash content of 5 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:2 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 3MPa, and after a thermal polycondensation reaction at a temperature of 410°C for 10 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 270°C, an mesophase content of 99.5%, and an H / C molar ratio of 0.64.

[0040] Embodiment 14: The spinnable mesophase pitch is obtained by the following method: S1, extracting cycloalkyl coker wax oil and furfural in a weight ratio of 1:1 at 55° C. by stirring for 30 minutes, and then standing and settling for 30 minutes to separate extract oil and raffinate oil; S2, filtering the raffinate oil at 100°C using a ceramic membrane with a pore size of 100 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 0 μg / g, and a cycloalkane content of 85%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 55% and an ash content of 0 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:2 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 0.1MPa, and after a thermal polycondensation reaction at a temperature of 440°C for 10 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 290°C, an mesophase content of 90.0%, and an H / C molar ratio of 0.55.

[0041] Embodiment 15: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the cycloalkyl catalytic cracking oil slurry and the extraction solvent at a weight ratio of 1:1 at 60° C. for 40 minutes, and then standing and settling for 40 minutes to separate the extracted oil and the raffinate oil; S2, filtering the raffinate oil at 80°C using a ceramic membrane with a pore size of 150 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 5 μg / g, and a cycloalkane content of 79%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 80% and an ash content of 0 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:2 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 3MPa, and after a thermal polycondensation reaction at a temperature of 400°C for 10 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 250°C, an mesophase content of 98.4%, and an H / C molar ratio of 0.60.

[0042] Embodiment 16: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the cycloalkyl catalytic cracking oil slurry and the extraction solvent at a weight ratio of 1:1 at 60° C. for 40 minutes, and then standing and settling for 40 minutes to separate the extracted oil and the raffinate oil; S2, filtering the raffinate oil at 150°C using a ceramic membrane with a pore size of 80 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 5 μg / g, and a cycloalkane content of 79%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 80% and an ash content of 0 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:3 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 2MPa, and after a thermal polycondensation reaction at a temperature of 400°C for 10 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 240°C, an mesophase content of 99.4%, and an H / C molar ratio of 0.64.

[0043] Embodiment 17: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the cycloalkyl catalytic cracking cycle oil and the extraction solvent at a weight ratio of 1:1 at 60° C. for 30 minutes, and then standing and settling for 30 minutes to separate the extracted oil and the raffinate oil; S2, filtering the raffinate oil at 100°C using a ceramic membrane with a pore size of 20 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 0 μg / g, and a cycloalkane content of 83%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 78% and an ash content of 0 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:2 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 4MPa, and after a thermal polycondensation reaction at a temperature of 420°C for 6 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 260°C, an mesophase content of 98.7%, and an H / C molar ratio of 0.63.

[0044] Embodiment 18: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the cycloalkyl catalytic cracking cycle oil and the extraction solvent at a weight ratio of 1:4 at 60° C. for 30 minutes, and then standing and settling for 30 minutes to separate the extracted oil and the raffinate oil; S2, filtering the raffinate oil at 100°C using a ceramic membrane with a pore size of 20 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 0 μg / g, and a cycloalkane content of 70%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 74% and an ash content of 5 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:3 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 1MPa, and after a thermal polycondensation reaction at a temperature of 440°C for 4 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 230°C, an mesophase content of 97.2%, and an H / C molar ratio of 0.65.

[0045] Embodiment 19: The spinnable mesophase pitch is obtained by the following method: S1, stirring and extracting the cycloalkyl minus four fraction oil and the extraction solvent at a weight ratio of 1:1 at 55° C. for 30 minutes, and then standing and settling for 30 minutes to separate the extracted oil and the raffinate oil; S2, filtering the raffinate oil at 80°C using a ceramic membrane with a pore size of 150 nm to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain a heavy raffinate oil with an initial distillation point greater than 400°C, an ash content of 0 μg / g, and a cycloalkane content of 84%; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining a refined extracted oil with an aromatic content of 50% and an ash content of 0 μg / g; S4, the refined extraction oil and the heavy extraction residue oil in a weight ratio of 10:1 are mixed as the co-carbonization feedstock oil, the co-carbonization feedstock oil is added into a high-pressure reactor, the air is replaced by nitrogen for 3 times, nitrogen is introduced into the high-pressure reactor to increase the pressure to 2MPa, and after a thermal polycondensation reaction at a temperature of 400°C for 7 hours, gas is produced during the reaction process, and the pressure in the reactor is controlled to be stable. After the reaction is completed, the pressure is released and the temperature is slowly lowered to obtain a spinnable mesophase asphalt with a softening point of 245°C, an mesophase content of 91.8%, and an H / C molar ratio of 0.60.

[0046] The spinnable mesophase pitch prepared in Examples 12 to 19 of the present invention has excellent performance, a softening point of 230° C. to 290° C., a mesophase content of 90.0% to 99.5% H / C, and a high molar ratio.

[0047] In summary, the preparation method of the spinnable mesophase asphalt provided by the present invention can deeply and accurately control the structure, composition and molecular weight distribution of aromatic-rich feedstock oil, has simple process flow and equipment, low preparation cost, controllable reaction conditions, and is easy to realize industrial production. The prepared spinnable mesophase asphalt has the characteristics of low softening point and high mesophase content.

[0048] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. A spinnable mesophase pitch, characterized in that Obtained as follows: S1, stirring and extracting the aromatics-rich feedstock oil and the extraction solvent in proportion, and then standing, settling and separating to obtain an extraction oil and a raffinate oil; S2, filtering the raffinate oil in a heated state to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain heavy raffinate oil; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining refined extracted oil; S4, mixing the refined extraction oil and the heavy extraction raffinate oil in proportion as co-carbonization feedstock oil, placing the co-carbonization feedstock oil in a nitrogen atmosphere, and then subjecting the co-carbonization feedstock oil to a thermal polycondensation reaction to obtain a spinnable mesophase pitch.

2. The spinnable mesophase pitch according to claim 1, characterized in that The aromatics-rich feedstock oil is one or more of cycloalkyl catalytic cracking oil slurry, cycloalkyl catalytic cracking cycle oil, cycloalkyl coker wax oil and cycloalkyl vacuum distillate oil; or / and, the extraction solvent is one or more of furfural, N,N-dimethylformamide and N-methylpyrrolidone.

3. The spinnable mesophase pitch according to claim 1 or 2, characterized in that In step S1, the weight ratio of the aromatic-rich feedstock oil to the extraction solvent is 1:1 to 4; or / and, in step S4, the weight ratio of the refined extraction oil to the heavy raffinate oil is 10:1 to 3.

4. The spinnable mesophase pitch according to claim 1, 2 or 3, characterized in that In step S1, the extraction temperature is 55°C to 65°C, the extraction time is 30min to 40min, and the static sedimentation time is 30min to 40min.

5. The spinnable mesophase pitch according to any one of claims 1 to 4, characterized in that In step S2, the heating temperature is 80°C to 150°C, and a ceramic membrane with a pore size of 20nm to 150nm is used as a filter membrane for filtration.

6. The spinnable mesophase pitch according to any one of claims 1 to 5, characterized in that In step S4, during the thermal polycondensation reaction, the reaction temperature is 400° C. to 450° C., the reaction pressure is 0.1 MPa to 4.0 MPa, and the reaction time is 4 h to 10 h.

7. The spinnable mesophase pitch according to any one of claims 1 to 6, characterized in that The heavy raffinate has an initial distillation point greater than 400°C, an ash content of 0 μg / g to 10 μg / g, and a cycloalkane content of 70% to 85%.

8. The spinnable mesophase pitch according to any one of claims 1 to 7, characterized in that The refined extract oil has an aromatic content of 50% to 80% and an ash content of 0μg / g to 5μg / g.

9. The spinnable mesophase pitch according to any one of claims 1 to 8, characterized in that The spinnable mesophase pitch has a softening point of 230° C. to 290° C., a mesophase content of 90.0% to 99.5%, and a H / C molar ratio of 0.55 to 0.

65.

10. A method for preparing a spinnable mesophase pitch according to any one of claims 2 to 9, characterized in that Proceed as follows: S1, stirring and extracting the aromatics-rich feedstock oil and the extraction solvent in proportion, and then standing, settling and separating to obtain an extraction oil and a raffinate oil; S2, filtering the raffinate oil in a heated state to remove impurities, and then subjecting the extracted oil after the impurities are removed to atmospheric and vacuum distillation to remove a small amount of extraction solvent and light components to obtain heavy raffinate oil; S3, heating and distilling the extracted oil, recovering the extraction solvent, and obtaining refined extracted oil; S4, mixing the refined extraction oil and the heavy extraction raffinate oil in proportion as co-carbonization feedstock oil, placing the co-carbonization feedstock oil in a nitrogen atmosphere, and then subjecting the co-carbonization feedstock oil to a thermal polycondensation reaction to obtain a spinnable mesophase pitch.