Low-softening-point spinnable mesophase pitch and continuous production process thereof

Abstract

The invention relates to a low-softening-point spinnable mesophase pitch and a continuous production process thereof, and belongs to the technical field of pitch-based carbon materials. The technical problems of low purity, high softening point, non-uniform structural composition, high production cost and the like of the mesophase pitch prepared by a process for producing the mesophase pitch from aromatic hydrocarbon-rich heavy oil in the prior art are solved. According to the continuous production process disclosed by the invention, coal-based or petroleum-based aromatic hydrocarbon-rich heavy oil is taken as a raw material, raw oil refining is realized through a continuous solvent extraction process, and shallow polycondensed asphalt is prepared by adopting a multi-section heating tubular reactor through a thermal polycondensation process; then the pitch is subjected to a supercritical or subcritical extraction process at a certain temperature and pressure to obtain the mesophase pitch with enriched polycyclic aromatic hydrocarbon molecules with low softening point, narrow molecular weight distribution and uniform structural composition, and the mesophase pitch has excellent spinning performance, so that the prepared carbon fiber has excellent mechanical properties and is suitable for industrial production. The high-value utilization of the aromatic hydrocarbon-rich heavy oil is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of pitch-based carbon materials, and in particular relates to a low-softening-point spinnable mesophase pitch and a continuous production process thereof. Background Art

[0002] As the trend of heavy oil resources becomes increasingly serious, the annual output of heavy residual oil in the world continues to increase, while traditional refining processes make it difficult to achieve efficient and clean utilization of heavy residual oil. In recent years, my country has continued to promote the implementation of policies such as "carbon peak" and "carbon neutrality", and how to achieve high added value and clean utilization of heavy residual oil has become a focus of increasing attention. Studies have found that heavy residual oil is rich in a large number of aromatic components. After special process treatment, the impurity components in the residual oil are fully removed, and it can become a high-quality precursor for the preparation of mesophase asphalt. In order to obtain high-quality mesophase asphalt, aromatic-rich heavy oil needs to meet the following conditions: 1. The aromatic content is greater than 60wt%; 2. The ash content is less than 50ppm; 3. The heteroatom (S, O) content is less than 2wt%. Therefore, the development of a suitable aromatic-rich heavy oil pretreatment process is the key to achieving high added value utilization of heavy oil.

[0003] Mesophase asphalt is a complex mixture composed of flaky polycyclic aromatic hydrocarbon molecules with a moderate degree of polycondensation. Its unique molecular orientation characteristics make it exhibit optical anisotropy. At the same time, this molecular orientation characteristic will be "inherited" to the corresponding derivatives. For example, asphalt-based carbon fibers derived from mesophase asphalt have high electrical and thermal conductivity and are widely used in defense, military industry, aerospace and other fields. In addition to regulating the properties of the raw oil, the preparation of high-performance mesophase asphalt also requires a suitable preparation process. The most commonly used process in industrial production is the thermal polycondensation method, but the traditional thermal polycondensation process has a high reaction temperature, and the degree of polycondensation of the obtained mesophase asphalt molecules is relatively large, resulting in a high asphalt softening point and the appearance of a small amount of coking products. This will not only affect the spinnability of the mesophase asphalt, but also reduce the corresponding mechanical properties of the carbon fiber.

[0004] Chinese patent (publication number 110041952A) provides a method for preparing mesophase pitch. The invention uses the heavy product prepared by the hot-melt catalytic process of lignite as raw material, and obtains mesophase pitch through thermal polycondensation, vacuum distillation, hydrogenation reaction, flash evaporation and thermal sensitization. However, the content of mesophase pitch obtained by this method is only 61.2%, and the two-phase coexisting asphalt is difficult to melt-spin due to the large difference in properties. Chinese patent (publication number 106147834B) provides a combined method for separating catalytic cracking oil slurry and preparing mesophase pitch. The invention first uses an extractant solvent to perform supercritical or subcritical extraction on the catalytic cracking oil slurry, and then the extracted mesophase component or its mixture with the extracted light component is subjected to hydrogenation treatment to remove impurity sulfur elements, and the hydrogenated tail oil or its mixture with the light component is used as a raw material to prepare mesophase pitch. Although this method can prepare mesophase pitch containing a wide-area structure, the softening point of the obtained mesophase pitch is relatively high, and the mesophase component containing optical structures such as mosaic and streamline, the inhomogeneity of the structural composition not only affects the spinnability of the pitch but also reduces the mechanical properties of the carbon fiber. A Chinese patent (publication number 110776943A) provides a method for preparing a spinnable mesophase pitch, which uses high-softening-point petroleum pitch as raw material, obtains purified pitch after thermal extraction and filtration, and uses this as raw material, octahydrophenanthrene as a hydrogen donor, and prepares the mesophase pitch through a thermal polycondensation reaction with a normal pressure purge process. The price of the hydrogen donor in this invention is relatively high, which increases the production cost of the mesophase pitch to a certain extent, and cannot meet the demand for low-cost asphalt-based carbon fiber. Summary of the invention

[0005] The present invention aims to solve the technical problems in the prior art of producing mesophase asphalt from aromatic-rich heavy oil, such as low purity of the obtained mesophase asphalt, high softening point, uneven structural composition, and high production cost. A low-softening-point spinnable mesophase asphalt and a continuous production process thereof are provided to realize the high-value utilization of aromatic-rich heavy oil.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The continuous production process of the low softening point spinnable mesophase pitch of the present invention comprises the following steps:

[0008] Step 1, selecting an organic solvent as an extractant, using a solvent extraction process to extract the preheated aromatic-rich heavy oil to obtain an extracted oil, and then removing the organic solvent after vacuum distillation to obtain a refined oil;

[0009] Step 2: heat polycondense the refined oil through a multi-stage heating tubular reactor, wherein the first stage treatment temperature is 200-280°C, the second stage treatment temperature is 280-320°C, the third stage treatment temperature is 320-380°C, and the flow rate of the refined oil is 40-100 ml / min, to obtain a two-phase asphalt;

[0010] Step 3: After cooling the two-phase asphalt, the asphalt is treated by supercritical or subcritical extraction process to obtain a low softening point spinnable mesophase asphalt.

[0011] Preferably, in step 1, the aromatics-rich heavy oil is first preheated to 90-110°C, and then the preheated aromatics-rich heavy oil is extracted with an organic solvent; more preferably, 100°C.

[0012] Preferably, in step 1, the aromatics-rich heavy oil includes one or more of medium- and low-temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue oil, and bio-tar.

[0013] Preferably, in step 1, the organic solvent is selected from one or more of n-heptane, n-hexane, furfural, petroleum ether and acetonitrile.

[0014] Preferably, in step 1, the extraction temperature of the solvent extraction process is 30-60° C., and the mass ratio of the organic solvent to the aromatics-rich heavy oil is 4:1-8:1.

[0015] Preferably, in step 1, the conditions for reduced pressure distillation are absolute vacuum 5 MPa, 50-100°C.

[0016] Preferably, in step 1, the flow rate of the solvent extraction process of the aromatics-rich heavy oil is 50-80 ml / min, more preferably 60 ml / min.

[0017] Preferably, in step 1, the ash content of the refined oil is 10-30 ppm, and the aromatic content is 62-70 wt%.

[0018] Preferably, in step 2, the multi-stage heating tubular reactor is divided into three reactors, which are connected in series, and each reactor is heated by microwaves; more preferably, the length of each reactor is 0.8 m.

[0019] Preferably, in step 2, the flow rate of the refined oil in the multi-stage heated tubular reactor is 50 ml / min.

[0020] Preferably, in step three, the extraction solvent of the supercritical or subcritical extraction process is selected from one or more of cyclohexane, piperidine, xylene, chloroform, and tetrahydrofuran, the extraction temperature is 200-300°C, the pressure is 20-30MPa, and the extraction time is 15-30min.

[0021] The present invention also provides low softening point spinnable mesophase asphalt prepared by the above production process, wherein the molecular weight distribution range of the mesophase asphalt is 600-800 and the softening point is 250-280°C.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The continuous production process of the low softening point spinnable mesophase asphalt of the present invention selects an organic solvent as an extractant, uses a continuous solvent extraction process to refine the crude oil, achieves target component enrichment, greatly improves production efficiency, and is easy to realize industrialized scale-up production.

[0024] The continuous production process of the low-softening-point spinnable mesophase asphalt of the present invention adopts a multi-stage heating tubular reactor to prepare the mesophase asphalt, which significantly reduces the thermal polycondensation temperature of the raw oil and can effectively avoid local overheating that causes excessive polycondensation of aromatic molecules to form coking products. At the same time, it is combined with a supercritical or subcritical extraction process to effectively regulate the molecular weight distribution of the mesophase asphalt, so that the mesophase asphalt presents a flow-basin-type optical structure at a lower softening point, which is beneficial to improving the spinning performance of the asphalt and the mechanical properties of the carbon fiber.

[0025] The continuous production process of the low softening point spinnable mesophase asphalt of the present invention overcomes the characteristics of complex raw oil composition and non-uniform reaction activity, and realizes the high-value utilization of aromatics-rich heavy oil.

[0026] The mesophase pitch of the present invention has a low softening point, a narrow molecular weight distribution, a uniform structural composition, is enriched with polycyclic aromatic hydrocarbon molecules, and has excellent spinning performance, and the prepared carbon fiber has excellent mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained without creative work.

[0028] Figure 1 The process flow chart of the continuous production process of the low softening point spinnable mesophase pitch of the present invention;

[0029] In the figure, 1, heating tank; 2, solvent extraction unit; 3, pressure reducing tower; 4, multi-stage heating tubular reactor; 5, cooling tank; 6, supercritical or subcritical extraction unit; 7, first cooling recovery tank; 8, second cooling recovery tank, 9, third cooling recovery tank. DETAILED DESCRIPTION

[0030] In order to have a deeper understanding of the present invention, the preferred embodiments of the present invention are described below to further illustrate the features and advantages of the present invention. Any changes or modifications that do not deviate from the spirit of the present invention can be understood by those skilled in the art. The scope of protection of the present invention is determined by the scope of the claims.

[0031] like Figure 1 As shown, the continuous production process of the low softening point spinnable mesophase pitch of the present invention comprises the following steps:

[0032] Step 1: using aromatics-rich heavy oil as feedstock, adding it into a heating tank 1 through a delivery pump, heating it to 90-110° C., preferably 100° C., and then delivering it to a solvent extraction unit 2 through a pipeline with a valve;

[0033] Step 2: In the solvent extraction unit 2, an organic solvent is selected as an extractant, and a solvent extraction process is used to extract the aromatic-rich heavy oil. The obtained extracted oil has a low ash content (10-30 ppm) and a high aromatic component content (62-70 wt%). The extracted oil is then transported to a vacuum tower 3 through a pipeline with a valve, and the organic solvent is removed by vacuum distillation (the organic solvent can also be recycled and reused) to obtain refined oil, and the raffinate oil is discharged from the solvent extraction unit 2;

[0034] Step 3: The refined oil in the vacuum tower 3 is transported to the multi-stage heating tubular reactor 4 via a pipeline, and the refined oil is subjected to thermal polycondensation. The first stage of the multi-stage heating tubular reactor 4 has a treatment temperature of 200-280°C, the second stage has a treatment temperature of 280-320°C, the third stage has a treatment temperature of 320-380°C, and the flow rate of the refined oil is 50 ml / min. Two-phase coexisting asphalt is obtained, and the two-phase coexisting asphalt is transported to the cooling tank 5 via a pipeline with a valve for cooling;

[0035] Step 4: The cooled two-phase coexisting asphalt is transported to the supercritical or subcritical extraction unit 6 via a pipeline, the obtained light component is cooled and recovered by the first cooling reflux tank 1, the obtained intermediate phase asphalt is cooled and recovered by the second reflux tank 2, that is, the low softening point spinnable intermediate phase asphalt, and the heavy component is cooled and recovered by the third cooling reflux tank 3 (different components are distinguished according to the sampling position of the supercritical or subcritical extraction unit 6).

[0036] In the above technical scheme, in step 1, the aromatics-rich heavy oil is used as the raw material, including one or more of medium- and low-temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue oil, and bio-tar.

[0037] In the above technical solution, in step 1, the flow rate of the aromatic-rich heavy oil transported to the solvent extraction unit 2 is 50-80 ml / min, preferably 60 ml / min.

[0038] In the above technical solution, in step 1, the conditions for reduced pressure distillation are absolute vacuum 5Mpa, 50-100°C.

[0039] In the above technical solution, in step 2, the organic solvent is selected from one or more of n-heptane, n-hexane, furfural, petroleum ether, and acetonitrile; preferably, a mixture of multiple organic solvents with different solubility parameters is selected, such as furfural and n-hexane in a mass ratio of 1:1.

[0040] In the above technical solution, in step 2, the extraction temperature of the solvent extraction process is 30-60°C, and the mass ratio of the organic solvent to the aromatics-rich heavy oil is 4:1-8:1.

[0041] In the above technical solution, in step 2, the ash content of the refined oil is 10-30 ppm, and the aromatic content is 62-70 wt%.

[0042] In the above technical solution, in step three, the multi-stage heating tubular reactor is divided into three reactors connected in series, each reactor is 0.8 m long and adopts microwave heating, that is, a microwave power regulator is separately provided to control the reaction temperature. It should be noted that the number of reaction tubes involved in the reaction and the temperature setting of each reactor can be flexibly adjusted according to the difference in raw materials.

[0043] In the above technical solution, in step 4, the extraction solvent of the supercritical or subcritical extraction process is selected from one or more of cyclohexane, piperidine, xylene, chloroform, and tetrahydrofuran, the extraction temperature is 200-300°C, the pressure is 20-30MPa, and the extraction time is 15-30min. The present invention also provides a low softening point spinnable mesophase asphalt prepared by the above production process, the molecular weight distribution range of the mesophase asphalt is 600-800, and the softening point is 250-280°C.

[0044] The terms used in the present invention generally have the meanings commonly understood by those of ordinary skill in the art, unless otherwise specified.

[0045] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with embodiments.

[0046] In the following examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources.

[0047] Example 1

[0048] 4 kg of catalytic cracking (FCC) oil slurry was added into the heating tank 1 through a delivery pump. The temperature of the heating tank 1 was set at 100°C. The valve was opened and the heated FCC oil slurry was added into the solvent extraction unit 2 at a flow rate of 60 ml / min. A mixed solution of furfural and n-hexane in a mass ratio of 1:1 was selected as the extraction solvent. The extraction temperature was 40°C, and the agent-oil mass ratio was set to 5:1. The extracted oil was transported to the vacuum tower 3, and the extraction solvent was recovered by vacuum distillation at 50°C to obtain refined oil. The refined oil is conveyed to a multi-stage heated tubular reactor 4 at 40 ml / min, the reaction temperature of the first stage is set to 200°C, the reaction temperature of the second stage is set to 280°C, and the reaction temperature of the third stage is set to 320°C. The reaction product is conveyed to a cooling tank 5 for cooling, and then conveyed to a supercritical or subcritical extraction unit 6. Chloroform is selected as the extractant, the extraction temperature is set to 280°C, the extraction pressure is set to 25 MPa, and the extraction time is set to 20 min. Three cooling recovery tanks are connected to the supercritical or subcritical extraction unit 6. A light component with an average molecular weight of 400 is obtained in the first cooling recovery tank 7, an intermediate phase asphalt with an average molecular weight of 680 is obtained in the second cooling recovery tank 8, and a heavy component with an average molecular weight of 990 is obtained in the third cooling recovery tank 9.

[0049] After testing, it was found that the method produced a mesophase asphalt with a mesophase content of 90% and a softening point of 247°C. Under a polarizing microscope, it was found to have a large domain structure. This was used as a raw material for melt spinning, pre-oxidation, and carbonization to obtain asphalt-based carbon fiber. According to the national standard ASTM D3379-75, the tensile modulus of the carbon fiber was measured to be 210 GPa, and the tensile strength was 1.5 GPa.

[0050] Example 2

[0051] 4 kg of catalytic cracking (FCC) oil slurry was added into the heating tank 1 through a delivery pump. The temperature of the heating tank 1 was set at 100°C. The valve was opened and the heated FCC oil slurry was added into the solvent extraction unit 2 at a flow rate of 60 ml / min. A mixed solution of furfural and n-hexane in a mass ratio of 1:1 was selected as the extraction solvent. The extraction temperature was 40°C, and the agent-oil mass ratio was set to 5:1. The extracted oil was transported to the vacuum tower 3, and the extraction solvent was recovered by vacuum distillation at 50°C to obtain refined oil. The refined oil is conveyed to a multi-stage heated tubular reactor 4 at 60 ml / min, the reaction temperature of the first stage is set to 250°C, the reaction temperature of the second stage is set to 280°C, and the reaction temperature of the third stage is set to 360°C. The reaction product is conveyed to a cooling tank 5 for cooling, and then conveyed to a supercritical or subcritical extraction unit 6. Chloroform is selected as the extractant, the extraction temperature is set to 280°C, the extraction pressure is set to 25 MPa, and the extraction time is set to 20 min. Three cooling recovery tanks are connected to the supercritical or subcritical extraction unit 6. A light component with an average molecular weight of 430 is obtained in the first cooling recovery tank 7, an intermediate phase asphalt with an average molecular weight of 710 is obtained in the second cooling recovery tank 8, and a heavy component with an average molecular weight of 1100 is obtained in the third cooling recovery tank 9.

[0052] After testing, it was found that the method produced an intermediate phase asphalt with an intermediate phase content of 93% and a softening point of 252°C. Under a polarizing microscope, it was found to have a large domain structure. Asphalt-based carbon fiber was obtained by melt spinning, pre-oxidation and carbonization using this as raw material. According to the national standard ASTM D3379-75, the tensile modulus of the carbon fiber was measured to be 280 GPa and the tensile strength was 1.8 GPa.

[0053] Example 3

[0054] 4 kg of catalytic cracking (FCC) oil slurry was added into the heating tank 1 through a delivery pump. The temperature of the heating tank 1 was set at 100°C. The valve was opened and the heated FCC oil slurry was added into the solvent extraction unit 2 at a flow rate of 60 ml / min. A mixed solution of furfural and n-hexane in a mass ratio of 1:1 was selected as the extraction solvent. The extraction temperature was 40°C, and the agent-oil mass ratio was set to 5:1. The extracted oil was transported to the vacuum tower 3, and the extraction solvent was recovered by vacuum distillation at 50°C to obtain refined oil. The refined oil is transported to a multi-stage heated tubular reactor 4 at 50 ml / min, the reaction temperature of the first stage is set to 240°C, the reaction temperature of the second stage is set to 300°C, and the reaction temperature of the third stage is set to 380°C. The reaction product is transported to a cooling tank 5 for cooling, and then transported to a supercritical or subcritical extraction unit 6. Chloroform is selected as the extractant, the extraction temperature is set to 280°C, the extraction pressure is set to 25 MPa, and the extraction time is set to 20 min. Three cooling recovery tanks are connected to the supercritical or subcritical extraction unit 6. A light component with an average molecular weight of 440 is obtained in the first cooling recovery tank 7, an intermediate phase asphalt with an average molecular weight of 710 is obtained in the second cooling recovery tank 8, and a heavy component with an average molecular weight of 1004 is obtained in the third cooling recovery tank 9.

[0055] After testing, it was found that the method produced an intermediate phase asphalt with an intermediate phase content of 96% and a softening point of 267°C. Under a polarizing microscope, it was found to have a large domain structure. Asphalt-based carbon fiber was obtained by melt spinning, pre-oxidation and carbonization using this as raw material. According to the national standard ASTM D3379-75, the tensile modulus of the carbon fiber was measured to be 380 GPa and the tensile strength was 2.0 GPa.

[0056] Example 4

[0057] 4 kg of catalytic cracking (FCC) oil slurry is added into the heating tank 1 through a delivery pump. The temperature of the heating tank 1 is set at 100°C. The valve is opened and the heated FCC oil slurry is added into the solvent extraction unit 2 at a flow rate of 60 ml / min. Furfural is selected as the extraction solvent. The extraction temperature is 30°C. The agent-oil mass ratio is set to 4:1. The extracted oil is delivered to the vacuum tower 3. The extraction solvent is recovered by vacuum distillation at 60°C and refined oil is obtained. The refined oil is transported to a multi-stage heated tubular reactor 4 at a flow rate of 50 ml / min, the reaction temperature of the first stage is set to 200° C., the reaction temperature of the second stage is set to 300° C., and the reaction temperature of the third stage is set to 350° C. The reaction product is transported to a cooling tank 5 for cooling, and then transported to a supercritical or subcritical extraction unit 6. Piperidine is selected as the extractant, the extraction temperature is set to 250° C., the extraction pressure is set to 20 MPa, and the extraction time is set to 15 min. Three cooling recovery tanks are connected to the supercritical or subcritical extraction unit 6. A light component with an average molecular weight of 470 is obtained in the first cooling recovery tank 7, an intermediate phase asphalt with an average molecular weight of 770 is obtained in the second cooling recovery tank 8, and a heavy component with an average molecular weight of 994 is obtained in the third cooling tube 9.

[0058] The method produces a mesophase asphalt with a mesophase content of 98%, a softening point of 260°C, and a large domain structure under a polarizing microscope. The asphalt is used as a raw material for melt spinning, pre-oxidation, and carbonization to obtain asphalt-based carbon fiber. The tensile modulus of the carbon fiber is measured to be 330 GPa and the tensile strength is 1.6 GPa according to the national standard ASTM D3379-75.

[0059] Example 5

[0060] 4 kg of catalytic cracking (FCC) oil slurry was added into the heating tank 1 through a delivery pump. The temperature of the heating tank 1 was set at 100°C. The valve was opened and the FCC oil slurry was added into the solvent extraction unit 2 at a flow rate of 60 ml / min. Petroleum ether was selected as the extraction solvent. The extraction temperature was 50°C. The solvent-oil mass ratio was set to 6:1. The extracted oil was delivered to the vacuum tower 3. The extraction solvent was recovered by vacuum distillation at 60°C and refined oil was obtained. The refined oil is transported to a multi-stage heated tubular reactor 4 at 50 ml / min, the reaction temperature of the first stage is set to 280°C, the reaction temperature of the second stage is set to 320°C, and the reaction temperature of the third stage is set to 380°C. The reaction product is transported to a cooling tank 5 for cooling, and then transported to a supercritical or subcritical extraction unit 6. Piperidine is selected as the extractant, the extraction temperature is set to 300°C, the extraction pressure is set to 30 MPa, and the extraction time is set to 30 min. Three cooling recovery tanks are connected to the supercritical or subcritical extraction unit 6. A light component with an average molecular weight of 500 is obtained in the first cooling recovery tank 7, an intermediate phase asphalt with an average molecular weight of 780 is obtained in the second cooling recovery tank 8, and a heavy component with an average molecular weight of 990 is obtained in the third cooling recovery tank 9.

[0061] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A continuous production process of low softening point spinnable mesophase pitch, characterized in that: Here are the steps: Step 1, selecting an organic solvent as an extractant, using a solvent extraction process to extract the preheated aromatic-rich heavy oil to obtain an extracted oil, and then removing the organic solvent after vacuum distillation to obtain a refined oil; Step 2: heat polycondense the refined oil through a multi-stage heating tubular reactor, wherein the first stage treatment temperature is 200-280°C, the second stage treatment temperature is 280-320°C, the third stage treatment temperature is 320-380°C, and the flow rate of the refined oil is 40-100 ml / min, to obtain a two-phase asphalt; Step 3: After cooling the two-phase asphalt, the asphalt is treated by supercritical or subcritical extraction process to obtain a low softening point spinnable mesophase asphalt.

2. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step 1, the aromatics-rich heavy oil is first preheated to 90-110° C., and then the preheated aromatics-rich heavy oil is extracted with an organic solvent.

3. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step 1, the aromatics-rich heavy oil includes one or more of medium- and low-temperature coal tar, catalytic cracking slurry, ethylene tar, vacuum residue oil, and bio-tar.

4. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step 1, the organic solvent is selected from one or more of n-heptane, n-hexane, furfural, petroleum ether, and acetonitrile, the extraction temperature of the solvent extraction process is 30-60° C., and the mass ratio of the organic solvent to the aromatics-rich heavy oil is 4:1-8:

1.

5. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step 1, the flow rate of the solvent extraction process of the aromatics-rich heavy oil is 50-80 ml / min.

6. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step 1, the ash content of the refined oil is 10-30 ppm, and the aromatic content is 62-70 wt%.

7. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step 2, the multi-stage heating tubular reactor is divided into three reactors, which are connected in series, and each reactor is heated by microwaves.

8. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step three, the extraction solvent of the supercritical or subcritical extraction process is selected from one or more of cyclohexane, piperidine, xylene, chloroform, and tetrahydrofuran.

9. The continuous production process of low softening point spinnable mesophase pitch according to claim 1, characterized in that: In step three, the extraction temperature is 200-300°C, the pressure is 20-30MPa, and the extraction time is 15-30min.

10. The low softening point spinnable mesophase pitch prepared by the continuous production process according to any one of claims 1 to 9, characterized in that: The molecular weight distribution range of the mesophase asphalt is 600-800, and the softening point is 250-280°C.

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