Co-production process and system of mesophase pitch and mesocarbon microbeads

Abstract

The invention discloses a co-production process and system for mesophase pitch and mesocarbon microbeads, and the process comprises the following steps: (1) carrying out heat treatment on a first raw material, and separating a liquid-phase material flow obtained after heat treatment to obtain a first material flow and a second material flow; (2) contacting the first material flow with an auxiliary agent to perform a first reaction, and obtaining a third material flow after the reaction is completed; (3) in the presence of a carrier gas, carrying out a second reaction on the third material flow to obtain mesophase pitch and a fourth material flow after the reaction is completed; (4) carrying out heat treatment on the second raw material under the inert atmosphere protection condition, and reacting to obtain pitch containing mesophase pellets and a fifth material flow; and (5) mixing the fifth material flow and the fourth material flow, and separating to obtain gas, light distillate oil, heavy distillate oil and tail oil. According to the co-production process and system of the mesophase pitch and the mesocarbon microbeads, ethylene tar can be converted into spinnable mesophase pitch with high additional value, the mesocarbon microbeads are co-produced, and the mesocarbon microbeads are uniform in particle size distribution.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon-based materials, and particularly relates to a co-production process of mesophase pitch and mesophase carbon microspheres. Background Art

[0002] Mesophase pitch is a high-quality carbon material precursor made from coal-based, petroleum-based, high molecular polymers, and other aromatic compounds, and has been widely used in the preparation of various carbon materials such as needle coke, foam carbon, and high-performance pitch-based carbon fibers. High-performance pitch-based carbon fibers are widely used in the aerospace field due to their high strength, high modulus, electrical conductivity, thermal conductivity, and other excellent properties.

[0003] CN112831334A and CN112645304A disclose a method for preparing mesophase pitch and mesophase carbon microspheres. Using heavy oil as the raw material, after n-heptane extraction, an organometallic complex / biomass material is doped in the deasphalted oil for shallow catalysis, and a free radical promoter is added to the heavy fraction obtained by vacuum distillation of the product to prepare mesophase pitch and mesophase carbon microspheres.

[0004] CN108441244A discloses a method for preparing mesophase carbon microspheres and mesophase pitch. The co-carbonization raw material obtained by mixing coal-based pitch with a first solvent is subjected to a first thermal condensation reaction, then a second solvent is added and mixed, dissolved, and the solid component obtained after separation is dried to obtain mesophase carbon microspheres, and the liquid component is distilled and subjected to a second thermal condensation reaction to obtain mesophase pitch.

[0005] CN104650938A discloses a co-production process method for needle coke, mesophase carbon microspheres, and high-quality pitch. The heavy-phase pitch generated by the pretreatment of the raw material pitch is mixed with the raw material pitch to produce mesophase carbon microspheres, and the rich pitch is mixed with the refined pitch obtained by the pretreatment of the raw material pitch as the raw material for needle coke.

[0006] CN105036116A discloses a method for preparing mesophase pitch or mesophase carbon microspheres from kerosene co-liquefaction residue. The kerosene co-liquefaction residue is subjected to two-stage extraction, and the asphaltene obtained by the secondary extraction is mixed with heavy oil in a certain proportion for co-carbonization thermal condensation to generate a thermal condensation product containing mesophase pitch or mesophase carbon microspheres, and after washing and drying, mesophase carbon microspheres are obtained.

[0007] Ethylene tar is mainly composed of polycyclic aromatic hydrocarbons and aromatic olefins, with relatively low contents of heteroatoms such as sulfur and nitrogen. However, its initial coking temperature is low, and substances such as coke that seriously affect the product quality are easily formed when preparing mesophase pitch from ethylene tar. At the same time, in the current process of preparing mesocarbon microbeads by thermal polycondensation, the obtained mesocarbon microbeads are prone to fusion and have a wide size distribution range. Therefore, in the process of preparing mesophase pitch from ethylene tar, how to ensure the quality of mesophase pitch products, and in the process of preparing mesocarbon microbeads by thermal polycondensation, how to ensure a uniform particle size distribution of carbon microbeads are the technical problems to be solved in this field currently. Summary of the Invention

[0008] Combined with the above analysis, in order to solve the problems existing in the prior art, the core purpose of the present invention is to provide a co-production process and system for mesophase pitch and mesocarbon microbeads, which can not only convert ethylene tar into spinnable mesophase pitch with high added value, but also co-produce mesocarbon microbeads with a uniform particle size distribution.

[0009] The present invention provides a co-production process for mesophase pitch and mesocarbon microbeads, and the process comprises the following steps:

[0010] (1) Heat-treat the first raw material, and after the heat treatment is completed, the obtained liquid-phase material flows through separation to obtain a first stream and a second stream;

[0011] (2) The first stream contacts with an auxiliary agent to carry out a first reaction, and after the reaction is completed, a third stream is obtained;

[0012] (3) In the presence of a carrier gas, the third stream carries out a second reaction, and after the reaction is completed, mesophase pitch and a fourth stream are obtained;

[0013] (4) Under the protection of an inert atmosphere, heat-treat the second raw material, and after the reaction, pitch containing mesophase microspheres and a fifth stream are obtained;

[0014] (5) The fifth stream and the fourth stream are mixed and separated to obtain gas, light distillate oil, heavy distillate oil and tail oil.

[0015] Preferably, in the co-production process of mesophase pitch and mesocarbon microbeads described above, the first raw material in step (1) is one or more of ethylene tar, butadiene tar, high-temperature coal tar, etc., preferably ethylene tar.

[0016] Preferably, in the co-production process of mesophase pitch and mesocarbon microbeads described above, the heat treatment in step (1) is generally carried out under the following operating conditions: the heat treatment temperature is 120 - 240 °C, preferably 130 - 220 °C, the heat treatment pressure is 0.01 - 10 MPa, preferably 0.5 - 5 MPa, and the residence time is 0.1 - 12 h, preferably 0.5 - 6 h.

[0017] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the heat treatment in step (1) is carried out in the presence of an inert atmosphere, and the inert atmosphere is nitrogen and / or inert gas, preferably nitrogen; the inert gas can be at least one of helium, neon, argon, krypton, and xenon.

[0018] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the 95% distillation temperature of the first feed stream in step (1) is 460 - 540 °C, preferably 460 - 500 °C.

[0019] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the method for separating the liquid feed stream obtained after the heat treatment in step (1) can be one or several of flash distillation, steam stripping, atmospheric distillation, vacuum distillation, etc., and preferably vacuum distillation is used.

[0020] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, a catalyst can be optionally used or not used during the heat treatment in step (1) as needed, and preferably a catalyst is used; the catalyst can be anhydrous aluminum chloride, and the addition amount of the catalyst is 1 wt% - 10 wt% of the weight of the first raw material, preferably 2 wt% - 5 wt%.

[0021] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the auxiliary agent in step (2) is a compound containing at least one aromatic ring, selected from one or more of methylnaphthalene, xylene, durene, tetralin, decalin, anthracene, and dihydroanthracene, preferably tetralin. Based on the weight ratio, the ratio of the auxiliary agent to the first feed stream is 1:100 - 50:100, preferably 10:100 - 30:100.

[0022] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the first reaction in step (2) is carried out under the following operating conditions: the reaction temperature is 360 - 500 °C, preferably 360 - 460 °C; the reaction pressure is atmospheric pressure - 5 MPa, preferably 0.1 - 3 MPa; the residence time of the material in the reactor is 1 - 20 h, preferably 2 - 10 h.

[0023] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the second reaction in step (3) is carried out under the following operating conditions: the pressure at the top of the reactor is 20 Pa - 1000 kPa (absolute pressure), preferably 20 Pa - 500 kPa (absolute pressure); the reaction temperature is 350 - 500 °C, preferably 360 - 460 °C, and the residence time is 6 - 15 h, preferably 6 - 12 h.

[0024] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, the carrier gas in step (3) can be one or more of water vapor, nitrogen, hydrogen, and inert gas, preferably water vapor or nitrogen; wherein the inert gas is one or more of helium, neon, argon, krypton, and xenon.

[0025] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, the heat treatment conditions in step (4) are as follows: the heat treatment pressure is normal pressure to 5 MPa, preferably normal pressure to 3 MPa; the heat treatment temperature is 360 to 480 °C, preferably 380 to 450 °C; the heat treatment time is 4 to 60 h, preferably 8 to 48 h.

[0026] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, the second stream obtained in step (1) enters the third reaction unit and is mixed with the second raw material for heat treatment.

[0027] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, it is preferred that the second raw material is first subjected to the first-stage heat treatment alone, and then the second stream is introduced and mixed for the second-stage heat treatment.

[0028] Furthermore, the first-stage heat treatment conditions are as follows: the first-stage heat treatment pressure is normal pressure to 5 MPa, preferably 1 to 3 MPa; the first-stage heat treatment temperature is 380 to 480 °C, preferably 400 to 450 °C; the first-stage heat treatment time is 2 to 20 h, preferably 4 to 12 h.

[0029] Furthermore, the second-stage heat treatment conditions are as follows: the second-stage heat treatment pressure is normal pressure to 1 MPa, preferably normal pressure to 0.5 MPa; the second-stage heat treatment temperature is 360 to 480 °C, preferably 380 to 450 °C; the second-stage heat treatment time is 2 to 48 h, preferably 4 to 36 h.

[0030] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, the second raw material in step (4) can be one or more of catalytic oil slurry, petroleum pitch, coal tar pitch, coal liquefaction residue, etc.

[0031] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, the pitch containing mesophase microspheres obtained in step (4) is further subjected to hot filtration, solvent extraction, washing, and drying to obtain mesophase carbon microspheres.

[0032] Preferably, in the co-production process of the above mesophase pitch and mesophase carbon microspheres, the pitch containing mesophase microspheres obtained in step (4) is first cooled to room temperature, and then added to the dispersion medium for hot filtration treatment to concentrate the mesophase microspheres. Then, it is extracted with a solvent until the solvent in the extractor is colorless and transparent, and then obtained mesophase carbon microspheres after washing and drying.

[0033] Furthermore, the dispersion medium is a hydrocarbon-containing compound, specifically one or more of diesel oil, anthracene oil, naphthalene oil, etc.; the hot filtration temperature is 200-250°C, and the filtration time is 1-4h.

[0034] Furthermore, the solvent used in solvent extraction is one or more of pyridine, quinoline, and toluene, and quinoline is preferred.

[0035] Furthermore, the washing is to repeatedly rinse the solid phase material rich in mesophase carbon microspheres extracted by solvent 2-3 times with acetone to wash away the residual organic solvent in the solid phase material.

[0036] Furthermore, the drying conditions are as follows: the drying temperature is 80-120°C, and the drying time is 8-24h.

[0037] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the light fraction oil obtained in step (5) can be returned to be mixed with the first raw material for heat treatment.

[0038] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the heavy fraction oil obtained in step (5) can be returned to be mixed with the first feed stream and / or the third feed stream for reaction.

[0039] Preferably, in the co-production process of the above-mentioned mesophase pitch and mesophase carbon microspheres, the cutting temperature of the light fraction oil and the heavy fraction oil in step (5) is 230-250°C, preferably 230-240°C; the cutting temperature of the heavy fraction oil and the tail oil is 410-430°C, preferably 410-420°C.

[0040] The second aspect of the present invention provides a mesophase pitch obtained by using the above co-production process of mesophase pitch and mesophase carbon microspheres.

[0041] Furthermore, in the above mesophase pitch, as a preferred embodiment, the softening point of the mesophase pitch is 270-310°C, and the mesophase morphology is a wide-area optical structure.

[0042] The third aspect of the present invention provides a method for preparing carbon fiber. The content of the preparation method is as follows: First, the mesophase pitch obtained by the co-production process of the above mesophase pitch and mesophase carbon microspheres is used as a raw material and sent to a spinning machine for spinning. The carbon fiber obtained by spinning can be obtained as a carbon fiber product after pre-oxidation, carbonization, and graphitization treatments.

[0043] Furthermore, in the above method for preparing carbon fiber, the spinning, pre-oxidation, carbonization, and graphitization treatments can all adopt any one of the existing mature processes in the art, and the specific operating conditions can be freely selected and adjusted according to needs.

[0044] In the above-mentioned method for preparing carbon fiber, the spinning process is generally melt spinning, and the spinning temperature is 30-50 °C higher than the softening point; the pre-oxidation medium is air, the pre-oxidation temperature is 250 °C, and the pre-oxidation time is 2 h; carbonization and graphitization treatments are carried out in an inert atmosphere, the carbonization temperature is 1100 °C, and the carbonization time is 1 h; the graphitization temperature is 2500 °C, and the graphitization time is 15 min.

[0045] In the fourth aspect of the present invention, a co-production system for mesophase pitch and mesophase carbon microspheres is provided. The co-production system includes a pretreatment unit, a first reaction unit, a second reaction unit, a third reaction unit, a first separation unit, and a second separation unit; wherein:

[0046] The pretreatment unit heat-treats the first raw material in the presence of an optional catalyst, and after heat treatment, a gas-phase stream and a liquid-phase stream are obtained;

[0047] The first separation unit separates the liquid-phase stream obtained after heat treatment in the pretreatment unit into a first stream and a second stream;

[0048] The first reaction unit contacts the first stream from the first separation unit with an auxiliary agent to carry out a first reaction, and after the reaction is completed, a third stream is obtained;

[0049] The second reaction unit contacts the third stream from the first reaction unit with a carrier gas in the presence of the carrier gas to carry out a second reaction, and after the reaction is completed, mesophase pitch and a fourth stream are obtained;

[0050] The third reaction unit is used to receive the second raw material and heat-treat the second raw material in an inert atmosphere to obtain pitch containing mesophase microspheres and a fifth stream;

[0051] The second separation unit is used to receive and separate the fourth stream from the second reaction unit and the fifth stream from the third reaction unit, and after separation, gas, light fraction oil, heavy fraction oil, and tail oil are obtained.

[0052] In the above-mentioned co-production system for mesophase pitch and mesophase carbon microspheres, as a preferred embodiment, the light fraction oil obtained by the second separation unit is connected to the pretreatment unit through a pipeline and mixed with the first raw material for heat treatment.

[0053] In the above-mentioned co-production system for mesophase pitch and mesophase carbon microspheres, as a preferred embodiment, the heavy fraction oil obtained by the second separation unit is connected to the first reaction unit and / or the second reaction unit through a pipeline, preferably connected to the second reaction unit, and mixed with the third stream to carry out the second reaction.

[0054] In the co-production system of the above-mentioned mesophase pitch and mesophase carbon microspheres, as a preferred embodiment, the first separation unit and the second separation unit adopt equipment with the function of separating liquid-phase materials, which can be at least one of equipment such as flash tanks, fractionating towers, etc., and preferably a fractionating tower. The specific type of the fractionating tower can be selected according to needs.

[0055] Compared with the prior art, the beneficial effects of the co-production process and system of mesophase pitch and mesophase carbon microspheres provided by the present invention are reflected in one or more of the following aspects:

[0056] 1. In the co-production process and system of mesophase pitch and mesophase carbon microspheres provided by the present invention, through different reaction units, the organic combination of simultaneously preparing mesophase pitch and mesophase carbon microspheres from two different raw materials (represented by ethylene tar and catalytic slurry) is realized. Moreover, the heavy fraction oil obtained by jointly separating the heat-treated oil and gas products of the catalytic slurry system in the third reaction unit and the heat-treated oil and gas products of the ethylene tar system in the second reaction unit is an aromatic-rich oil with relatively high thermal stability. Entering the second reaction unit can regulate and reduce the viscosity of the reaction system. At the same time, with the introduction of the heavy fraction oil, some components of the second raw material slurry system can also be introduced. These components can effectively improve the domain size in the microstructure of mesophase pitch, which is beneficial to the formation and development of wide-domain mesophase.

[0057] 2. In the co-production process and system of mesophase pitch and mesophase carbon microspheres provided by the present invention, the second stream obtained by the first separation unit enters the third reaction unit and reacts synergistically with the second raw material in the third reaction unit. Among them, the second stream can not only serve as a nucleating agent to promote the generation of mesophase microspheres, but also serve as a viscosity regulator to weaken the fusion between the microspheres, making the particle size distribution of the obtained mesophase microspheres more uniform. The light fraction oil obtained by the second separation unit is recycled to the pretreatment unit, which can improve the yield of the first stream.

[0058] 3. In the co-production process and system of mesophase pitch and mesophase carbon microspheres provided by the present invention, ethylene tar first enters the pretreatment unit. Preferably, under the action of a catalyst, the easily coking components in the ethylene tar are caused to undergo a condensation reaction to remove the coking precursors. The liquid-phase stream obtained after pretreatment is divided into a first stream and a second stream according to the distillation range. Among them, the content of carbon-carbon double bonds in the first stream has been greatly reduced compared with the untreated ethylene tar raw material, and the thermal stability has been significantly improved, avoiding problems such as poor product homogeneity and spinnability caused by directly using ethylene tar as a raw material to prepare mesophase pitch. The obtained mesophase pitch has a softening point adjustable between 270-330°C, a mesophase content greater than 95%. Moreover, the raw materials used in this method are easily available, and the cost of the produced high-quality mesophase pitch product is low, which is conducive to realizing the large-scale production and sustainable development of high-quality mesophase pitch, and provides a means for high-value utilization of difficult-to-treat ethylene tar.

[0059] 4. In the co-production process and system of mesophase pitch and mesophase carbon microspheres provided by the present invention, through operations such as low-temperature catalytic condensation and separation, while improving the thermal stability of ethylene tar, the aromatic-rich components are retained. Through the synergistic effect of operations such as catalysis, separation, hydrogen supply, and heat treatment, the preparation of high-quality mesophase pitch from ethylene tar is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of the co-production process and system of mesophase pitch and mesophase carbon microspheres of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0061] The method of the present invention will be further described in detail below in conjunction with the drawings and embodiments, but the following embodiments do not limit the method of the present invention.

[0062] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0063] The description of the exemplary embodiments is intended to be read in conjunction with the drawings, which are considered to be a part of the entire written description. In the specification, relative terms such as "lower", "upper", "horizontal", "vertical", "above", "below", "upward", "downward", "top" and "bottom" and their derivatives (e.g., "horizontally", "downwardly", "upwardly", etc.) should be interpreted as the directions shown in the drawings described at that time. These relative terms are for ease of description and do not require the device to be constructed or operated in a specific orientation. Unless otherwise specified, the "connection" referred to in the present invention means a relationship in which structures are directly or indirectly fixed or connected to each other through an intermediate structure.

[0064] As Figure 1As shown in the figure, the present invention provides a co-production process and system for mesophase pitch and mesophase carbon microspheres. The specific process of the co-production process is as follows: The first raw material 1 enters the pretreatment unit 2 and undergoes heat treatment in the presence of an optional catalyst. After heat treatment, a gas-phase stream 3 and a liquid-phase stream 4 are obtained. The liquid-phase stream 4 enters the first separation unit 5, and after separation, a first stream 6 and a second stream 7 are obtained. The first stream 6 enters the first reaction unit 8 and undergoes a first reaction in contact with an auxiliary agent. After the reaction is completed, the obtained third stream 9 enters the second reaction unit 10 and undergoes a second reaction in the presence of a carrier gas 12. After the reaction, mesophase pitch 13 and a fourth stream 11 are obtained. Among them, the generated mesophase pitch 13 is discharged from the bottom of the second reaction unit 10 and can enter the subsequent spinning unit for further treatment. The second raw material 19 and the second stream 7 enter the third reaction unit 20 and undergo heat treatment in an inert atmosphere. After the reaction, pitch containing mesophase microspheres 22 and a fifth stream 21 are obtained. The fourth stream 11 and the fifth stream 21 enter the second separation unit 14, and after separation, gas 15, light distillate oil 16, heavy distillate oil 17, and tail oil 18 are obtained. The light distillate oil can be recycled back to the pretreatment unit 2 for treatment together with the first raw material 1. The heavy distillate oil can be recycled back to the first reaction unit and / or the second reaction unit for treatment, preferably recycled back to the second reaction unit for treatment together with the third stream. The pitch containing mesophase microspheres 22 obtained from the third reaction unit is obtained as mesophase carbon microspheres after hot filtration, solvent washing, and drying.

[0065] In this article, the specific process conditions for producing carbon fiber from mesophase pitch are as follows: First, the mesophase pitch enters a spinning machine for melt spinning. The spinning temperature is 30 - 50 °C higher than the softening point. The pre-oxidation medium is air, the pre-oxidation temperature is 250 °C, and the pre-oxidation time is 2 h. Carbonization and graphitization treatments are carried out in an inert atmosphere. The carbonization temperature is 1100 °C, and the carbonization time is 1 h. The graphitization temperature is 2500 °C, and the graphitization time is 15 min.

[0066] In this article, the carbon fiber strength is measured by the standard method of GB / T 31290-2014. The particle size distribution of mesophase carbon microspheres is measured by the standard method of GB / T 19077-2016.

[0067] In this article, the first raw material uses ethylene tar, and the second raw material uses catalytic slurry. The specific properties are shown in Table 1.

[0068] Example 1

[0069] Example 1 uses Figure 1The co-production process shown, in which the light distillate oil is returned to the pretreatment unit for reaction, and the heavy distillate oil is returned to the second reaction unit for further reaction. The catalyst used is anhydrous aluminum chloride, and the dosage is 2 wt% of the raw material. The reaction is carried out under nitrogen conditions. The reaction conditions of the pretreatment unit are: reaction temperature is 170 °C, reaction pressure is 5.0 MPa, and residence time is 3 h. The 95% distillation temperature of the first feed stream is 500 °C. The promoter is tetralin, and the dosage of the promoter is 10 wt% of the first feed stream. The conditions of the first reaction unit are: reaction temperature is 450 °C, reaction pressure is 5 MPa, and residence time is 6 h. The resulting reaction feed oil enters the second reaction unit and continues to react under nitrogen purge. The conditions of the second reaction unit are: reaction temperature is 460 °C, reaction pressure is 0.5 MPa, and residence time is 10 h. The generated mesophase pitch enters the subsequent spinning unit, and carbon fiber can be obtained through spinning, pre-oxidation, carbonization, and graphitization treatments. The catalytic slurry enters the third reaction unit and is carried out in the presence of a nitrogen atmosphere. The conditions of the third reaction unit are: reaction pressure is 3 MPa, reaction temperature is 400 °C, and reaction time is 10 h; then the second feed stream is introduced into the third reaction unit to be mixed with the reaction product of the catalytic slurry for heat treatment. The mass ratio of the second feed stream to the reaction product of the catalytic slurry is 10:100. At this time, the reaction conditions of the third reaction unit are: carried out in the presence of a nitrogen atmosphere, reaction pressure is 0.5 MPa, reaction temperature is 420 °C, and reaction time is 12 h. After the pitch containing mesophase spheres obtained from the third reaction unit is cooled to room temperature (25 °C), it is added to diesel oil and subjected to hot filtration at 250 °C to concentrate the mesophase spheres. Then, it is extracted with quinoline solvent until the solvent in the extractor is colorless and transparent, washed repeatedly with acetone 3 times, and dried at 120 °C for 20 h to obtain mesophase carbon microspheres. The cutting point temperature of the light distillate oil and heavy distillate oil obtained by separating the fifth feed stream and the fourth feed stream is 240 °C, and the cutting point temperature of the heavy distillate oil and the tail oil is 420 °C. The light distillate oil is returned to the pretreatment unit for further reaction, and the heavy distillate oil is returned to the second reaction unit for further reaction. The reaction results are shown in Table 2 and Table 3.

[0070] Example 2

[0071] It is basically the same as Example 1. The differences are as follows: the conditions of the pretreatment unit are that the catalyst dosage is 5 wt% of the raw materials, and it is protected in nitrogen. The reaction conditions of the pretreatment unit are that the reaction temperature is 220 °C, the reaction pressure is 3.0 MPa, and the residence time is 0.5 h; the 95% distillation temperature of the first feed stream is 480 °C. The conditions of the first reaction unit are that the additive is decalin, and the additive dosage is 20 wt% of the first feed stream. The reaction conditions of the first reaction unit are that the reaction temperature is 420 °C, the reaction pressure is 3 MPa, and the residence time is 12 h; the catalytic slurry is not heat-treated and reacts with the second feed stream at a mass ratio of 20:100 in the third reaction unit. The conditions of the third reaction unit are that it is in a nitrogen atmosphere, the reaction pressure is 0.5 MPa, the reaction temperature is 450 °C, and the reaction time is 8 h. In addition, the light distillate oil separated from the fifth feed stream and the fourth feed stream is discharged from the device, and the heavy distillate oil returns to the second reaction unit for continuous reaction. The reaction results are shown in Tables 2 and 3.

[0072] Example 3

[0073] Example 3 uses Figure 1 the preparation method shown, which is basically the same as Example 2. The differences are as follows: the 95% distillation temperature of the first feed stream in the first separation unit is 460 °C. The conditions of the first reaction unit are that the additive dosage is 30 wt% of the first light oil. The reaction conditions of the first reaction unit are that the reaction temperature is 380 °C, the reaction pressure is 2 MPa, and the residence time is 15 h; the reaction conditions of the second reaction unit are that the reaction temperature is 420 °C, the reaction pressure is 1000 Pa (absolute pressure), and the residence time is 5 h. The reaction results are shown in Tables 2 and 3.

[0074] Comparative Example 1

[0075] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, there is no pretreatment unit and the first separation unit, and the third reaction unit uses only the catalytic slurry as the raw material, and other conditions are basically the same as those in Example 1.

[0076] Comparative Example 2

[0077] The difference between Comparative Example 2 and Example 2 is that in the first reaction unit of Comparative Example 2, there is no additive; the mass ratio of the second raw material to the second feed stream in Comparative Example 2 is 15:100, and other conditions are basically the same as those in Example 2.

[0078] For the mesophase pitch obtained in the above examples and comparative examples, its softening point, mesophase pitch content, and spinnability are tested. The carbon fiber obtained by spinning, pre-oxidation, carbonization, and graphitization of the mesophase pitch is tested for its tensile strength, and the results are shown in Table 2; the particle size distribution results of the obtained mesophase carbon microspheres are shown in Table 3.

[0079] Table 1 Raw Material Properties

[0080] Item Ethylene tar Catalytic slurry oil Ash, wt% 0.018 0.016 Sulfur, wt% 0.12 0.50 Distillation range distribution / °C 5％ 213.2 346.8 95％ 691.8 635.2 Four-component, wt% Saturates 0.60 23.38 Aromatics 83.21 73.29 Resin 14.56 3.19 Asphaltenes 1.63 0.14

[0081] Table 2 Properties of Mesophase Pitch and Carbon Fiber

[0082]

[0083] Table 3 Particle Size Distribution of Mesophase Carbon Microspheres

[0084]

Claims

1. A co-production process of mesophase pitch and mesophase carbon microspheres, the process comprising the following steps: (1) Heat-treat the first raw material, and after the heat treatment is completed, the liquid-phase material obtained flows through separation to obtain a first stream and a second stream; (2) The first stream contacts with an auxiliary agent to carry out a first reaction, and after the reaction is completed, a third stream is obtained; the auxiliary agent is a compound containing at least one aromatic ring; (3) In the presence of a carrier gas, the third stream carries out a second reaction, and after the reaction is completed, mesophase pitch and a fourth stream are obtained; (4) Heat-treat the second raw material under the protection of an inert atmosphere, and after the reaction, pitch containing mesophase microspheres and a fifth stream are obtained; (5) The fifth stream is mixed with the fourth stream and separated to obtain gas, light distillate oil, heavy distillate oil and tail oil.

2. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The first raw material in step (1) is one or more of ethylene tar, butadiene tar, and high-temperature coal tar, preferably ethylene tar.

3. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The heat treatment in step (1) is carried out under the following operating conditions: the heat treatment temperature is 120 - 240 °C, preferably 130 - 220 °C, the heat treatment pressure is 0.01 - 10 MPa, preferably 0.5 - 5 MPa, and the residence time is 0.1 - 12 h, preferably 0.5 - 6 h.

4. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The heat treatment in step (1) is carried out in the presence of an inert atmosphere, and the inert atmosphere is nitrogen and / or inert gas, preferably nitrogen.

5. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The 95% distillation temperature of the first stream in step (1) is 460 - 540 °C, preferably 460 - 500 °C.

6. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: During the heat treatment process in step (1), a catalyst is optionally used or not used as needed, preferably a catalyst is used; the catalyst is anhydrous aluminum chloride, and the addition amount of the catalyst is 1 wt% - 10 wt% of the weight of the first raw material, preferably 2 wt% - 5 wt%.

7. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The auxiliary agent in step (2) is selected from one or more of methylnaphthalene, xylene, pyromellitene, tetrahydronaphthalene, decahydronaphthalene, anthracene, and dihydroanthracene, preferably tetrahydronaphthalene; based on the weight ratio, the ratio of the auxiliary agent to the first stream is 1:100 - 50:100, preferably 10:100 - 30:

100.

8. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The first reaction in step (2) is carried out under the following operating conditions: the reaction temperature is 360 - 500 °C, preferably 360 - 460 °C; the reaction pressure is atmospheric pressure - 5 MPa, preferably 0.1 - 3 MPa; the residence time of the material in the reactor is 1 - 20 h, preferably 2 - 10 h.

9. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The second reaction in step (3) is carried out under the following operating conditions: the pressure at the top of the reactor is 20 Pa - 1000 kPa, preferably 20 Pa - 500 kPa; the reaction temperature is 350 - 500 °C, preferably 360 - 460 °C, and the residence time is 6 - 15 h, preferably 6 - 12 h.

10. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The carrier gas in step (3) is one or more of steam, nitrogen, hydrogen, and inert gas, preferably steam or nitrogen.

11. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The heat treatment conditions in step (4) are as follows: the heat treatment pressure is atmospheric pressure - 5 MPa, preferably atmospheric pressure - 3 MPa; the heat treatment temperature is 360 - 480 °C, preferably 380 - 450 °C; the heat treatment time is 4 - 60 h, preferably 8 - 48 h.

12. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The second stream obtained in step (1) enters the third reaction unit to be mixed with the second raw material for heat treatment.

13. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1 or 12, characterized in that: The second raw material is first subjected to the first-stage heat treatment alone and then introduced into the second stream to be mixed for the second-stage heat treatment together.

14. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 13, characterized in that: The first-stage heat treatment conditions are as follows: the first-stage heat treatment pressure is atmospheric pressure - 5 MPa, preferably 1 - 3 MPa; the first-stage heat treatment temperature is 380 - 480 °C, preferably 400 - 450 °C; the first-stage heat treatment time is 2 - 20 h, preferably 4 - 12 h.

15. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 13, characterized in that: The second-stage heat treatment conditions are as follows: the second-stage heat treatment pressure is atmospheric pressure - 1 MPa, preferably atmospheric pressure - 0.5 MPa; the second-stage heat treatment temperature is 360 - 480 °C, preferably 380 - 450 °C; the second-stage heat treatment time is 2 - 48 h, preferably 4 - 36 h.

16. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The second raw material in step (4) is one or more of catalytic oil slurry, petroleum pitch, coal tar pitch, and coal liquefaction residue.

17. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The pitch containing mesophase spheres obtained in step (4) is further subjected to hot filtration, solvent extraction, washing, and drying to obtain mesophase carbon microspheres.

18. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The pitch containing mesophase spheres obtained in step (4) is first cooled to room temperature, then added to a dispersion medium for hot filtration treatment to concentrate the mesophase spheres, and then extracted with a solvent until the solvent in the extractor is colorless and transparent, and then washed and dried to obtain mesophase carbon microspheres.

19. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 18, characterized in that: The dispersion medium is a hydrocarbon-containing compound, selected from one or more of diesel oil, anthracene oil, and naphthalene oil; the hot filtration temperature is 200-250 °C, and the filtration time is 1-4 h.

20. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 18, characterized in that: The solvent used for solvent extraction is one or more of pyridine, quinoline, and toluene, and quinoline is preferred.

21. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The light distillate oil obtained in step (5) is returned to be mixed with the first raw material for heat treatment.

22. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The heavy distillate oil obtained in step (5) is returned to be mixed with the first feed stream and / or the third feed stream for reaction.

23. The co-production process of mesophase pitch and mesophase carbon microspheres according to claim 1, characterized in that: The cutting temperature of the light distillate oil and the heavy distillate oil in step (5) is 230-250 °C, preferably 230-240 °C; the cutting temperature of the heavy distillate oil and the tail oil is 410-430 °C, preferably 410-420 °C.

24. A mesophase pitch obtained by using the co-production process of mesophase pitch and mesophase carbon microspheres according to any one of claims 1-23.

25. The mesophase pitch according to claim 23, characterized in that: The softening point of the mesophase pitch is 270-310 °C, and the mesophase morphology is a wide-area optical structure.

26. A method for preparing carbon fiber, the preparation method is as follows: First, the mesophase pitch according to claim 24 or 25 is used as a raw material and sent to a spinning machine for spinning, and the carbon fiber obtained by spinning is subjected to pre-oxidation, carbonization, and graphitization treatments to obtain a carbon fiber product.

27. A co-production system of mesophase pitch and mesophase carbon microspheres, the co-production system includes a pretreatment unit, a first reaction unit, a second reaction unit, a third reaction unit, a first separation unit, and a second separation unit; wherein: The pretreatment unit performs heat treatment on the first raw material in the presence of an optional catalyst, and a gas-phase feed stream and a liquid-phase feed stream are obtained after the heat treatment; The first separation unit separates the liquid-phase feed stream obtained after heat treatment by the pretreatment unit to obtain a first feed stream and a second feed stream; The first reaction unit, the first feed stream from the first separation unit contacts with an auxiliary agent to carry out a first reaction, and a third feed stream is obtained after the reaction is completed; The second reaction unit, in the presence of a carrier gas, the third feed stream from the first reaction unit contacts the carrier gas to carry out a second reaction, and after the reaction is completed, mesophase pitch and a fourth feed stream are obtained; The third reaction unit is used to receive a second raw material and perform heat treatment on the second raw material under the protection of an inert atmosphere, and after the treatment, pitch containing mesophase microspheres and a fifth feed stream are obtained; The second separation unit is used to receive and separate the fourth feed stream from the second reaction unit and the fifth feed stream from the third reaction unit, and after separation, gas, light distillate oil, heavy distillate oil and tail oil are obtained.

28. The co-production system of mesophase pitch and mesophase carbon microspheres according to claim 27, characterized in that: The light distillate oil obtained by the second separation unit is connected to the pretreatment unit through a pipeline and mixed with the first raw material for heat treatment.

29. The co-production system of mesophase pitch and mesophase carbon microspheres according to claim 27, characterized in that: The heavy distillate oil obtained by the second separation unit is connected to the first reaction unit and / or the second reaction unit through a pipeline, preferably connected to the second reaction unit, and mixed with the third feed stream to carry out the second reaction.

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