A method and system for producing mesocarbon microbeads

Abstract

This invention discloses a method and system for producing mesophase carbon microspheres. The method involves hydrogenating purified catalytic slurry, followed by separation to obtain light fraction, middle fraction, and tail oil. The middle fraction is divided into two streams: the first stream undergoes cracking, with the cracking products recycled; the second stream undergoes a first heat treatment, and the heat-treated product is pulverized to obtain a solid first feed stream, a first solvent, and silicone oil, which are then subjected to a second heat treatment. The resulting reaction product is then centrifuged, washed, and dried to obtain mesophase carbon microspheres. The production system includes a purification unit, a hydrogenation reaction unit, a gas-liquid separation unit, a fractionation unit, a cracking reaction unit, a first heat treatment unit, and a second heat treatment unit. This invention proposes an optimized approach to preparing mesophase carbon microsphere raw materials, yielding high-quality mesophase pitch raw materials and mesophase carbon microsphere products.

Description

Technical Field

[0001] This invention belongs to the field of carbon materials and relates to a method and system for producing mesophase carbon microspheres. Background Technology

[0002] In 1973, Japanese scholars first separated anisotropic microspheres generated during the heat treatment of asphalt from the asphalt matrix, and named the separated micron-sized microspheres mesophase carbon microspheres. Due to their excellent chemical stability, high bulk density, ease of graphitization, good thermal stability, and excellent electrical and thermal conductivity, mesophase carbon microspheres are a high-quality precursor for the preparation of high-performance carbon materials, attracting great interest from carbon researchers. Currently, they are used in the development of high-density, high-strength C / C composite materials, high-performance liquid chromatography column materials, high specific surface area activated carbon materials, and lithium-ion battery anode materials.

[0003] CN1308113A discloses a method for preparing mesophase carbon microspheres through co-condensation. This method uses medium-temperature coal tar pitch and secondary petroleum heavy oil with low quinoline insoluble content as raw materials, subjecting them to a mixed heating co-condensation reaction to obtain pitch product containing mesophase carbon microspheres. The product is then hot-melted and filtered using a mixture of coal tar and light petroleum fractions, followed by extraction with organic solvents such as toluene to obtain the mesophase carbon microspheres. This method uses highly toxic organic solvents such as toluene as the extraction liquid, posing a significant environmental hazard, and the yield is low, only 20-30%.

[0004] CN101920956A discloses a method for efficiently preparing pitch-based mesophase carbon microspheres, which uses medium-temperature coal tar pitch and high-temperature coal tar pitch as raw materials and adds rosin as an additive. The specific process is as follows: The raw materials used for preparation include: basic raw materials and additives. Pitch-based carbon microspheres are prepared through raw material preparation, polymerization reaction, pyrolysis reaction, separation of pyrolysis products and drying process; the basic raw materials are one or two of medium-temperature coal tar pitch and high-temperature coal tar pitch, and the additives are one or two of rosin and disproportionated rosin.

[0005] Catalytic slurry oil, rich in aromatics, is a high-quality raw material for producing mesophase carbon microspheres. However, it contains high levels of ash and sulfur, generally requiring desolidification and desulfurization treatment before it can be used as a raw material for producing mesophase carbon microspheres. Currently, the process of preparing mesophase carbon microspheres using catalytic slurry oil as a raw material generally suffers from low yield, difficult separation, the need for large amounts of toxic organic solvents, and excessively wide diameter distribution of the obtained mesophase carbon microspheres. Summary of the Invention

[0006] During the research process, the applicant discovered that during the hydrodesulfurization treatment of the catalytic slurry, some aromatic rings in the slurry were also saturated through hydrogenation and further converted into aromatics with a large number of alkyl and / or cycloalkyl side chains. These side-chain-containing aromatics first undergo side-chain breaking reactions during the subsequent production of mesophase carbon microspheres, generating a large number of small-molecule hydrocarbons. On the one hand, the newly generated small-molecule hydrocarbons continuously escape, causing disturbance to the reaction system and hindering the formation of a broad-area mesophase; on the other hand, some small-molecule hydrocarbons, such as monocyclic aromatics, cannot escape the reaction system and inevitably undergo condensation reactions while remaining in the system. During the reaction cycle, these small molecules do not have enough time to form sufficiently large molecules and solidify into coke before forming a broad-area mesophase. Therefore, the hydrotreated catalytic slurry is not conducive to the formation of a broad-area mesophase, resulting in a low yield of mesophase asphalt.

[0007] To address the shortcomings of existing technologies, the main objective of this invention is to provide a method and system for producing mesophase carbon microspheres. This invention, from a molecular management perspective, utilizes in-depth analysis of the molecular reactivity of raw materials and the correlation analysis between raw material composition and the performance of mesophase carbon microspheres to propose optimization directions for raw materials, thereby obtaining high-quality mesophase carbon microsphere products. This solves the problem of low yield of mesophase carbon microspheres in existing technologies due to the desolidification and desulfurization treatment of catalytic oil slurry.

[0008] To achieve the above-mentioned objective, the first aspect of the present invention provides a method for producing mesophase carbon microspheres, the method comprising the following:

[0009] (1) In the presence of hydrogen, the catalytic slurry enters the hydrogenation unit and comes into contact with the hydrogenation catalyst to undergo a hydrogenation reaction. The hydrogenation reaction effluent is separated to obtain a gas phase stream and a liquid phase stream. The liquid phase stream is separated to obtain light fraction, middle fraction and tail oil.

[0010] (2) The intermediate fraction obtained in step (1) is further divided into a first stream and a second stream. The first stream enters the cracking unit for cracking reaction, and the cracking reaction products are recycled back to be processed together with the liquid stream obtained in step (1).

[0011] (3) The second stream of material obtained in step (2) enters the first heat treatment unit and undergoes the first heat treatment in the presence of an inert atmosphere. The first heat treatment product is crushed to obtain the first solid stream.

[0012] (4) The solid first stream, first solvent and silicone oil obtained in step (3) enter the second heat treatment unit, are mixed evenly and then subjected to the second heat treatment. After cooling, they are separated, washed and dried to obtain mesophase carbon microspheres.

[0013] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the ash content of the catalytic slurry in step (1) is no more than 0.08 t%, preferably no more than 0.05 wt%. When the ash content is high, the slurry is preferably subjected to impurity removal and solidification treatment first. Specifically, one or a combination of methods such as filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation can be used, with filtration being the preferred method. The filtration temperature of the catalytic slurry is further 120℃~280℃, preferably 170℃~230℃.

[0014] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the hydrogenation unit in step (1) is equipped with at least one hydrogenation reactor. When two or more hydrogenation reactors are set up, there are no special restrictions on the connection method between the reactors, and they are generally connected in series. The hydrogenation reactor can be selected from one or a combination of several of the following: fluidized bed reactor, suspended bed reactor, fixed bed reactor, etc., with a fixed bed reactor being preferred.

[0015] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the hydrogenation catalyst in step (1) can be an existing commercial catalyst, such as the FZC series hydrogenation catalyst developed by the Dalian Petrochemical Research Institute of Sinopec; or it can be prepared according to existing methods disclosed in the art. Typically, the hydrogenation catalyst includes a support and an active component, the support is generally alumina, and the active component is an oxide of a Group VIB and / or Group VIII metal.

[0016] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the operating conditions of the hydrogenation unit in step (1) are generally as follows: reaction pressure is 2 MPa to 20 MPa, preferably 4 MPa to 8 MPa; reaction temperature is 300℃ to 480℃, preferably 330℃ to 390℃; hydrogen-to-oil volume ratio is 100 to 2500, preferably 500 to 1800; and liquid hourly space velocity is 0.1 h⁻¹. -1 ~2.0h -1 Preferably 0.7h -1 ~1.2h -1 .

[0017] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the 5% distillation temperature of the intermediate fraction in step (1) is 360℃~430℃, preferably 385℃~410℃, and the 95% distillation temperature is 440℃~500℃, preferably 455℃~475℃.

[0018] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the light fraction obtained in step (1) can be fed into the condensation unit for reaction, or directly discharged as a product; or part of it can be fed into the condensation unit for reaction, and part of it can be discharged as a product. Furthermore, the condensation unit can be at least one of a tubular reactor, a tower reactor, or a tank reactor, preferably a tower reactor. The reaction conditions of the condensation unit are generally controlled as follows: reaction temperature of 350℃~550℃, preferably 400℃~460℃; reaction pressure of 0.1MPa~5MPa, preferably 0.8MPa~3.0MPa; residence time of 0.01h~50h, preferably 0.3h~24h. After separation, the reaction products obtained from the condensation reaction yield top oil and bottom oil. The bottom oil 5% distillation temperature is generally controlled at 300℃~420℃, preferably 330℃~370℃. The top oil can be directly discharged from the device, or it can be used as a diluent to be mixed with the catalytic oil slurry for impurity removal and solidification treatment; the bottom oil is recycled back to be separated together with the liquid phase material stream obtained in step (1).

[0019] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, a condensation catalyst is preferably added during the condensation reaction. The condensation reaction is carried out under the action of the condensation catalyst, which includes a support and an active component. The support is one or a combination of several of kaolin, montmorillonite, alumina, and silica-containing alumina, preferably alumina. The active component is at least one oxide of Group IVB and / or Group VIB metals, such as zirconium, tungsten, molybdenum, etc. Based on the weight of the catalyst, the content of the active component is 0.1wt% to 50wt%, preferably 5wt% to 25wt%. The condensation catalyst can be spherical, cylindrical, cloverleaf, four-leaf, Raschig ring, etc., or a combination of several of these shapes.

[0020] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the tail oil discharge device in step (1) can be used as a raw material for producing low-sulfur petroleum coke.

[0021] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the cracking unit in step (2) is equipped with at least one reactor. The reactor can be one or a combination of tubular reactors, tower reactors, and tank reactors, with a tower reactor being preferred. The operating conditions of the cracking unit are generally controlled as follows: reaction pressure is 0.1MPa to 5MPa, preferably 0.2MPa to 1.0MPa; reaction temperature is 380℃ to 520℃, preferably 420℃ to 490℃; residence time is 0.01h to 30h, preferably 0.1h to 3h. It is further preferred that a carrier gas is introduced during the cracking reaction. The carrier gas can be one or more of water vapor, nitrogen, and inert gases (such as helium, neon, and argon), with water vapor being preferred; the mass ratio of middle distillate oil to carrier gas is 100:0.1 to 100:20, preferably 100:1 to 100:8.

[0022] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the mass ratio of the second stream to the first stream in step (2) is 1:9 to 8:2, preferably 3:7 to 7:3.

[0023] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the operating conditions of the first heat treatment unit in step (3) are as follows: the reaction pressure is 1-10 MPa, preferably 5-10 MPa; the reaction temperature is 420-460℃, preferably 440-460℃; the treatment time is 8-20 h, preferably 12-16 h.

[0024] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the inert atmosphere in step (3) can be one or more of nitrogen, helium, neon, argon, krypton, and xenon, preferably nitrogen.

[0025] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the particle size of the first solid phase material obtained after pulverization in step (3) is not greater than 100 micrometers. The pulverization can be carried out by a pulverizer, and the blade speed of the pulverizer is generally 10000 to 30000 r / min.

[0026] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the weight ratio of the first solid phase feed to the first solvent in step (4) is 1:10 to 50, preferably 1:10 to 20.

[0027] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the weight ratio of the first solid phase feed to the silicone oil in step (4) is 1:1 to 10, preferably 1:5 to 10.

[0028] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the first solvent in step (4) is at least one of petroleum ether, methyl ethyl ketone, carbon tetrachloride, etc., preferably petroleum ether.

[0029] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the first solid phase material obtained in step (3) of step (4) is preferably mixed evenly with the first solvent, and then further mixed evenly with silicone oil before undergoing a second heat treatment.

[0030] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the silicone oil mentioned in step (4) is one or more of methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil, and cyanide silicone oil, preferably phenyl silicone oil.

[0031] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the second heat treatment in step (4) includes two stages, wherein the first stage heat treatment temperature is 60-90℃, the heating rate is 1-5℃, and the heat treatment time is 5-30min; the second stage heat treatment temperature is 260-290℃, the heating rate is 5-10℃, and the heat treatment time is 5-10min.

[0032] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the separation in step (4) is a liquid-solid two-phase separation. Any one or more of the existing methods in the art that can achieve liquid-solid two-phase separation can be used, specifically any one of centrifugal separation, filtration separation, etc., with centrifugal separation being preferred. Those skilled in the art can freely choose according to actual needs.

[0033] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the washing in step (4) is performed by rinsing the solid material containing mesophase carbon microspheres 2 to 3 times with one of petroleum ether, methyl ethyl ketone or carbon tetrachloride.

[0034] Furthermore, in the above-mentioned method for producing mesophase carbon microspheres, the drying temperature in step (4) is 80-120°C, and the drying is preferably carried out under vacuum conditions with a vacuum degree of 1000-10000 Pa.

[0035] A second aspect of the present invention provides a system for producing mesophase carbon microspheres, comprising:

[0036] The hydrogenation unit is used to receive hydrogen and catalytic slurry, and a hydrogenation reaction takes place under the action of a hydrogenation catalyst;

[0037] The separation unit is used to receive the hydrogenation reaction effluent from the hydrogenation unit and separate it into a gaseous stream and a liquid stream.

[0038] The fractionation unit receives the liquid stream from the separation unit and fractionates it to obtain light fraction, middle fraction and tail oil. The middle fraction is further divided into a first stream and a second stream.

[0039] The cracking unit receives the first stream of material from the fractionation unit, and the cracking products obtained after the reaction are recycled back to the fractionation unit and processed together with the liquid stream obtained from the separation unit.

[0040] The first heat treatment unit is used to receive the second stream from the fractionation unit and perform the first heat treatment in the presence of an inert atmosphere. The product of the first heat treatment is crushed to obtain a solid first stream.

[0041] The second heat treatment unit is used to receive the first solid-phase feed stream, the first solvent, and the silicone oil from the first heat treatment unit, mix them evenly, and then perform a second heat treatment. After cooling, the mixture is separated, washed, and dried to obtain mesophase carbon microspheres.

[0042] Furthermore, the above-mentioned mesophase carbon microsphere production system includes a purification unit. The catalytic slurry preferably enters the purification unit for desolidification treatment. The purification unit can adopt one or a combination of methods such as filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation. Filtration is preferred. The further filtration equipment can be one or a combination of sintered metal powder filter cartridges, metal wire mesh filter cartridges, and ceramic membrane filter cartridges. Ceramic membrane filter cartridges are preferred.

[0043] Furthermore, in the aforementioned mesophase carbon microsphere production system, the hydrogenation unit includes at least one hydrogenation reactor. When two or more hydrogenation reactors are used, there are no particular restrictions on the connection method between the reactors; they are generally connected in series. The hydrogenation reactor can be selected from one or a combination of several of the following: fluidized bed reactor, suspended bed reactor, fixed bed reactor, etc., with a fixed bed reactor being preferred.

[0044] Furthermore, in the above-mentioned mesophase carbon microsphere production system, the separation unit can be any of the devices capable of achieving gas-liquid two-phase separation. Generally, the gas-liquid separation unit includes a hot high-pressure separator, a cold high-pressure separator, a hot low-pressure separator, and a cold low-pressure separator.

[0045] Furthermore, in the above-mentioned production system of mesophase carbon microspheres, the fractionation unit includes at least one fractionation tower, which can be either a packed tower or a plate tower.

[0046] Furthermore, in the above-mentioned mesophase carbon microsphere production system, the cracking unit is equipped with at least one reactor, which can be one or a combination of tubular reactors, tower reactors, and tank reactors, with tower reactors being preferred.

[0047] Furthermore, the aforementioned mesophase carbon microsphere production system includes a condensation unit for receiving light oil from the fractionation unit. The reaction products from the condensation reaction are separated to obtain top oil and bottom oil. The bottom oil's 5% distillation temperature is generally controlled at 300℃–420℃, preferably 330℃–370℃. The top oil can be discharged directly from the unit or returned as a diluent to the purification unit for mixing with the catalytic oil slurry for purification. The bottom oil is recycled back to the fractionation unit and processed together with the liquid stream obtained from the separation unit. The condensation unit can employ at least one of a tubular reactor, a tower reactor, or a tank reactor, with a tower reactor being preferred.

[0048] Furthermore, in the above-mentioned production system of mesophase carbon microspheres, the first heat treatment unit can be at least one of a tower reactor or a tank reactor, preferably a tower reactor.

[0049] Furthermore, in the above-mentioned production system of mesophase carbon microspheres, the second heat treatment unit can be at least one of a tower reactor or a tank reactor, preferably a tower reactor.

[0050] Compared with the prior art, the mesophase carbon microsphere production method and production system provided by the present invention have the following advantages:

[0051] (1) The mesophase carbon microsphere production method provided by this invention optimizes the molecular structure of the raw materials used for producing mesophase carbon microspheres from a molecular management perspective. The middle fraction obtained after hydrogenation of catalytic oil slurry is subjected to cracking reaction. The cracking products are mixed and blended with the hydrogenated oil slurry as the raw material for mesophase carbon microspheres. The cracking products generate less gas and light oil during the heat treatment reaction, resulting in less disturbance to the reaction system. The blending of cracking products and hydrogenated oil slurry ensures a moderate amount of light components generated in the system, preventing excessive disturbance, and promotes the directional arrangement of condensation macromolecules. This effectively mitigates the impact of small molecule hydrocarbon generation on the formation of the broad-area mesophase during the heat treatment reaction. It avoids the problem of producing more gas and light oil when using only hydrogenated oil slurry as raw material for producing mesophase carbon microspheres, which causes significant disturbance to the system upon escape, hindering the formation of the broad-area mesophase and resulting in a low yield of mesophase pitch. This invention addresses the problem that during the desulfurization process of catalytic oil slurry through hydrotreating, some aromatic rings of the aromatics become saturated, transforming into aromatics with numerous alkyl or cycloalkyl side chains. In the preparation of mesophase pitch, these aromatics first undergo side-chain breaking reactions, generating a large number of small-molecule hydrocarbons. On one hand, the continuous escape of these small-molecule hydrocarbons disturbs the reaction system, hindering the formation of a broad-area mesophase. On the other hand, some small-molecule hydrocarbons, such as monocyclic aromatics, may not escape and remain in the system undergoing condensation reactions. Within the reaction cycle, these small-molecule hydrocarbons do not have enough time to form sufficiently large molecules before solidifying into coke, failing to form a broad-area mesophase pitch and resulting in a low yield of mesophase pitch. The method of this invention can prepare mesophase pitch with a larger optical structure, achieving an over-the-top (OTC) texture index.

[0052] (2) In the method for producing mesophase carbon microspheres provided by the present invention, the first heat treatment is carried out under high temperature and high pressure conditions. Under these conditions, it is beneficial for the thermal condensation reaction to occur, increasing the pressure reduces the viscosity of the reaction system, increases the fluidity of the reaction system, makes the reaction uniform, avoids local overheating in the reaction system, avoids coking, and increases the yield of mesophase pitch.

[0053] (3) In the method for producing mesophase carbon microspheres provided by this invention, a first solvent and silicone oil are introduced in the second heat treatment. The use of the first solvent can fully wet the small particles of mesophase pitch, so that the small particles of pitch are uniformly dispersed in the high-temperature resistant silicone oil to form a uniformly mixed suspension. This avoids the fusion of small particles with each other, thereby obtaining mesophase carbon microspheres with uniform particle size and improving the yield of mesophase carbon microspheres. Moreover, the method for producing mesophase carbon microspheres of this invention is economical and environmentally friendly, and does not use highly toxic organic solvents such as toluene, pyridine, and quinoline as extractants. The organic solvents used in this invention are not only less toxic and can be reused, but also have a simple recovery process.

[0054] (4) In the method for producing mesophase carbon microspheres provided by this invention, all fractions of the raw material catalytic slurry are hydrogenated. The five-ring and above aromatic hydrocarbons contained in the catalytic slurry are successively hydrogenated, fractionated, and cracked. After hydrogenation, these aromatic hydrocarbons are converted into tetracyclic aromatic hydrocarbons with saturated side chains, or even tricyclic aromatic hydrocarbons with saturated side chains. These aromatic hydrocarbons are further converted into tetracyclic or tricyclic aromatic hydrocarbons with short side chains through cracking. They are ideal raw materials for producing high-quality mesophase carbon microspheres and can make the most effective use of the five-ring and above aromatic hydrocarbons in the catalytic slurry. This solves the problem that the five-ring and above aromatic hydrocarbons in the existing catalytic slurry are not rationally utilized and cannot be used as raw materials for producing mesophase carbon microspheres. The method of this invention can convert the five-ring and above aromatic hydrocarbons in the catalytic slurry into mesophase carbon microsphere raw materials, improve the utilization efficiency of the catalytic slurry, increase the yield of mesophase carbon microsphere raw materials and mesophase carbon microspheres, and enhance the economic value of the catalytic slurry. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the method and system for producing mesophase carbon microspheres according to the present invention.

[0056] Figure 2 Example 4: Polarized light microscope image of the intermediate phase pitch of the reaction intermediate product.

[0057] Figure 3 Polarized light microscope image of the mesophase carbon microspheres obtained in Example 4.

[0058] Figure 4 A schematic diagram of the production method and system for comparative example 1, showing the production of mesophase carbon microspheres. Detailed Implementation

[0059] The process and effects of the method of the present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments do not constitute a limitation on the method of the present invention.

[0060] like Figure 1 As shown, the process flow of the mesophase carbon microsphere production method provided by the present invention is as follows: Catalytic slurry 1 first enters purification unit 2 for desolidification and purification treatment. The resulting purified slurry 9 is mixed with hydrogen 12 and enters hydrogenation unit 3, where it contacts the hydrogenation catalyst to carry out a hydrogenation reaction. The hydrogenation reaction effluent 10 enters separation unit 4 for separation, resulting in a gaseous stream 11 and a liquid stream 13. The gaseous stream 11 is compressed by hydrogen compressor 5 and then sent to hydrogenation reaction unit 3 as circulating hydrogen 12. The liquid stream 13 enters fractionation unit 6 for separation, resulting in a light fraction 14, a middle fraction 15, and tail oil 21. The middle fraction is further divided into a first stream 15 and a second stream 16. The light fraction 14 is discharged from a device (not shown in the figure) or enters condensation unit 7 for a condensation reaction (e.g., ...). Figure 1 As shown), the reaction products are separated to obtain top oil 19 and bottom oil 20. Top oil 19 is discharged from the top of the reactor and can be used as a diluent to mix with catalytic slurry 1 and sent to purification unit 2. Bottom oil 20 obtained from the condensation reaction is returned to fractionation unit 6 for processing. Tail oil 21 obtained from fractionation unit 6 can be used as raw material for producing low-sulfur petroleum coke and sent to a conventional delayed coking unit. The first feed stream 15 is sent to cracking unit 8, where a cracking reaction occurs under the action of carrier gas 17. The resulting cracking product 18 is also returned to fractionation unit 6. The second feed stream 16 enters the first heat treatment unit 22 and undergoes the first heat treatment under an inert atmosphere. The first heat treatment product is pulverized to obtain solid first feed stream 23. The solid first feed stream 23, the first solvent 25, and the silicone oil 26 obtained from the first heat treatment unit enter the second heat treatment unit. After being mixed evenly, the second heat treatment is performed. After cooling, it is separated, washed, and dried to obtain mesophase carbon microspheres 27.

[0061] The properties of the catalytic slurry used in the embodiments and comparative examples of this invention are shown in Table 1. The hydrogenation catalyst used is FZC-34BT (developed by the Dalian Petrochemical Research Institute of Sinopec). The purification unit uses a filter, and the carrier gas is steam. The silicone oil used in the embodiments of this invention is phenyl silicone oil.

[0062] Table 1 Properties of Catalytic Slurry

[0063] project Catalytic slurry Sulfur content, wt% 0.97 Ash content, wt% 0.22 5% distillation temperature / ℃ 323 95% distillation temperature / ℃ 576

[0064] Example 1

[0065] Example 1 uses Figure 1 The process flow shown involves the catalytic oil slurry undergoing desolidification treatment before entering the hydrogenation reactor along with hydrogen to contact the catalyst. The hydrogenation reaction conditions are: reaction temperature 368℃, reaction pressure 5.7MPa, hydrogen-to-oil volume ratio 1200, and liquid hourly space velocity 0.83h⁻¹. -1The obtained hydrogenated liquid product is sent to the fractionation unit, where the separated light oil and tail oil are discharged from the device. The separated middle distillate oil has a 5% distillation temperature of 400℃ and a 95% distillation temperature of 460℃. The middle distillate oil is divided into two streams, with a mass ratio of 4:6 between the first and second streams. The second stream is sent to the cracking reactor for reaction under the following conditions: reaction temperature of 463℃, reaction pressure of 0.6 MPa, residence time of 1 h, and a middle distillate oil to steam mass ratio of 100:5. The first stream enters the first heat treatment unit for treatment under nitrogen atmosphere. The first heat treatment conditions are: pressure of 5 MPa, temperature of 420℃, heating rate of 5℃ / min, and treatment time of 12 h. After the reaction, the solid first stream (mesophase pitch) is pulverized into particles smaller than 100 micrometers. Then, petroleum ether was added, with a weight ratio of mesophase pitch to petroleum ether of 1:10. After stirring evenly, silicone oil was added, with a weight ratio of mesophase pitch to silicone oil of 1:5. After stirring evenly, the mixture was heated to 60°C at a rate of 2°C / min, while simultaneously recovering the vaporized petroleum ether. This temperature was maintained for 5 minutes, and then the temperature was further increased to 290°C at a rate of 5°C / min. After processing for 5 minutes, heating was stopped, and the reaction product was cooled to room temperature. The reaction product was centrifuged, the liquid in the upper part of the reactor was recovered, and petroleum ether was added to the remaining solid material in the lower part of the reactor. The mixture was washed three times, filtered, and dried at 100°C to obtain the product, mesophase carbon microspheres, with a yield of 42.12 wt%.

[0066] Example 2

[0067] Example 2 adopts Figure 1The process flow shown is basically the same as that in Example 1, except that the light oil separated from the fractionation unit is sent to the condensation reaction unit for reaction. The condensation reaction conditions are: reaction temperature 428℃, reaction pressure 1.6 MPa, and residence time 12 h. The condensation reaction products are divided into top oil and bottom oil. The top oil is discharged from the device, and the bottom oil is distilled at 365℃ (5% distillation temperature). The first stream enters the first heat treatment unit and is treated under nitrogen conditions. The first heat treatment conditions are: pressure 10 MPa, temperature 440℃, heating rate 5℃ / min, and treatment time 8 h. After the reaction, the first solid stream (mesophase asphalt) is pulverized into small particles smaller than 100 micrometers. Then, petroleum ether was added, with a weight ratio of mesophase pitch to petroleum ether of 1:5. After stirring evenly, silicone oil was added, with a weight ratio of mesophase pitch to silicone oil of 1:10. After stirring evenly, the mixture was heated to 90°C at a rate of 5°C / min, while simultaneously recovering the vaporized petroleum ether. This temperature was maintained for 30 min, and then the temperature was further increased to 280°C at a rate of 10°C / min for 10 min. Heating was then stopped, and the reaction product was cooled to room temperature. The reaction product was centrifuged, the liquid in the upper part of the reactor was recovered, and petroleum ether was added to the remaining solid material in the lower part of the reactor. The mixture was washed three times, filtered, and dried at 100°C to obtain the product, mesophase carbon microspheres, with a yield of 49.31 wt%.

[0068] Example 3

[0069] Example 3 operates under essentially the same conditions as Example 2, except for the cracking reaction conditions: reaction temperature 442℃, reaction pressure 0.4 MPa, residence time 1.8 h, and the mass ratio of middle distillate oil to steam 100:3. The first feed stream enters the first heat treatment unit and is treated under nitrogen conditions. The first heat treatment conditions are: pressure 5 MPa, temperature 460℃, heating rate 5℃ / min, and treatment time 16 h. After the reaction, the solid first feed stream (mesophase pitch) is pulverized into particles smaller than 100 micrometers. Then, petroleum ether is added, with a weight ratio of mesophase pitch to petroleum ether of 1:10. After stirring evenly, silicone oil is added, with a weight ratio of mesophase pitch to silicone oil of 1:10. After stirring and mixing evenly, the temperature is raised to 90℃ at a rate of 2℃ / min, while simultaneously recovering the vaporized petroleum ether. This temperature is maintained for 20 min, and then the temperature is raised to 260℃ at a rate of 5℃ / min. After 10 min of treatment, heating is stopped, and the reaction product is cooled to room temperature. The reaction product was centrifuged, the liquid in the upper part of the reactor was recovered, and petroleum ether was added to the remaining solid material in the lower part of the reactor. After washing three times and filtering, the product was dried at 100°C to obtain mesophase carbon microspheres with a yield of 51.85 wt%.

[0070] Example 4

[0071] Example 4 operates under essentially the same conditions as Example 3, except that the middle distillate oil is divided into two streams, with a mass ratio of 6:4 between the first and second streams; and a catalyst is used in the condensation reaction process. Specifically, the condensation catalyst uses alumina as a support and 7.5wt% ZrO2-5wt% MoO2 as the active component, with a cloverleaf structure. The yield of mesophase carbon microspheres is 56.58wt%.

[0072] Comparative Example 1

[0073] Comparative Example 1 uses existing technology; see details below. Figure 4 The catalytic slurry 1 is first purified by the purification unit 2, and the resulting purified slurry 9 enters the fractionation unit 6 for separation. After separation, light oil 14, middle distillate oil 16 and tail oil 21 are obtained. The separated light oil 14 and tail oil 21 are discharged from the device. The middle distillate oil 16 is mixed with hydrogen 12 and enters the hydrogenation reaction unit 3, where it contacts the hydrogenation catalyst to carry out the hydrogenation reaction. The hydrogenation reaction effluent 10 enters the gas-liquid separation unit 4 for separation, and after separation, gaseous product 11 and liquid product 13 are obtained. Gaseous product 11 is compressed by hydrogen compressor 5 and sent to hydrogenation reaction unit 3 as recycled hydrogen 12. Liquid product 13 enters fractionation unit 25 for separation, yielding light fraction (gas and naphtha) 29 and heavy fraction 27. Heavy fraction 27 enters the first heat treatment unit for processing under nitrogen conditions: pressure 5 MPa, temperature 440℃, heating rate 5℃ / min, and treatment time 12 h. After the reaction, the first solid stream (mesophase pitch) is pulverized into particles smaller than 100 micrometers. Then, petroleum ether 25 is added, with a weight ratio of mesophase pitch to petroleum ether of 1:10. After stirring evenly, silicone oil 26 is added, with a weight ratio of mesophase pitch to silicone oil of 1:5. After stirring and mixing evenly, the temperature is raised to 60℃ at a rate of 2℃ / min, while recovering the vaporized petroleum ether. This temperature is maintained for 20 min, and then the temperature is raised to 290℃. After processing for 10 min, heating is stopped, and the reaction product is cooled to room temperature. The reaction product was centrifuged, the liquid in the upper part of the reactor was recovered, and petroleum ether was added to the remaining solid material in the lower part of the reactor. After washing three times and filtering, the product was dried at 100°C to obtain mesophase carbon microspheres with a yield of 25.68 wt%.

[0074] Comparative Example 2

[0075] The process is essentially the same as in Example 1, except that a cracking reaction unit is not included. The middle distillate oil obtained from the fractionation unit directly enters the first heat treatment unit for processing under nitrogen conditions. The first heat treatment conditions are: pressure 5 MPa, temperature 440°C, heating rate 5°C / h, and treatment time 12h. After the reaction, the first solid stream (mesophase pitch) is pulverized into particles smaller than 100 micrometers. Then, petroleum ether is added, with a weight ratio of mesophase pitch to petroleum ether of 1:10. After stirring evenly, silicone oil is added, with a weight ratio of mesophase pitch to silicone oil of 1:5. After stirring and mixing evenly, the temperature is raised to 60°C at a rate of 2°C / min, while simultaneously recovering the vaporized petroleum ether. This temperature is maintained for 5 minutes, and then the temperature is raised to 290°C. After processing for 5 minutes, heating is stopped, and the reaction product is cooled to room temperature. The reaction product was centrifuged, the liquid in the upper part of the reactor was recovered, and petroleum ether was added to the remaining solid material in the lower part of the reactor. The mixture was washed three times, filtered, and dried at 100°C to obtain the product mesophase carbon microspheres with a yield of 23.15 wt%.

Claims

1. A method for producing mesophase carbon microspheres, the method comprising the following: (1) In the presence of hydrogen, the catalytic slurry enters the hydrogenation unit and comes into contact with the hydrogenation catalyst to undergo a hydrogenation reaction. The hydrogenation reaction effluent is separated to obtain a gaseous stream and a liquid stream. The liquid stream is separated to obtain light fraction, middle fraction and tail oil. The 5% distillation temperature of the middle fraction is 360℃~430℃, and the 95% distillation temperature is 440℃~500℃. (2) The intermediate fraction obtained in step (1) is further divided into a first stream and a second stream. The first stream enters the cracking unit for cracking reaction. The cracking reaction products are recycled back to be processed together with the liquid stream obtained in step (1). The operating conditions of the cracking unit are controlled as follows: the reaction pressure is 0.1MPa~5MPa, the reaction temperature is 380℃~520℃, and the residence time is 0.01h~30h. (3) The second stream of material obtained in step (2) enters the first heat treatment unit and undergoes the first heat treatment in the presence of an inert atmosphere. The first heat treatment product is crushed to obtain the first solid stream. (4) The solid first stream, first solvent and silicone oil obtained in step (3) enter the second heat treatment unit, are mixed evenly and then subjected to the second heat treatment. After cooling, they are separated, washed and dried to obtain mesophase carbon microspheres.

2. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: In step (1), the ash content of the catalytic oil slurry is no more than 0.08 wt%.

3. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: In step (1), the ash content of the catalytic oil slurry is no more than 0.05 wt%.

4. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The catalytic oil slurry is first subjected to impurity removal and solidification treatment, using one or more of the following methods: filtration, centrifugal sedimentation, flocculation precipitation, and vacuum distillation.

5. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The catalytic oil slurry is first subjected to impurity removal and solidification treatment by filtration.

6. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The operating conditions of the hydrogenation unit in step (1) are as follows: reaction pressure is 2 MPa to 20 MPa, reaction temperature is 300℃ to 480℃, hydrogen-to-oil volume ratio is 100 to 2500, and liquid hourly space velocity is 0.1 h⁻¹. -1 ~2.0h -1 .

7. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The operating conditions of the hydrogenation unit in step (1) are as follows: reaction pressure is 4 MPa to 8 MPa, reaction temperature is 330°C to 390°C, hydrogen-to-oil volume ratio is 500 to 1800, and liquid hourly space velocity is 0.7 h⁻¹. -1 ~1.2h -1 .

8. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The 5% distillation temperature of the middle fraction in step (1) is 385℃~410℃, and the 95% distillation temperature is 455℃~475℃.

9. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The light fraction obtained in step (1) enters the condensation unit for reaction, or is directly discharged from the device as a product; or part of it enters the condensation unit for reaction, and part of it is discharged from the device as a product.

10. The method for producing mesophase carbon microspheres according to claim 9, characterized in that: The reaction conditions of the condensation unit are controlled as follows: reaction temperature is 350℃~550℃, reaction pressure is 0.1MPa~5MPa, and residence time is 0.01h~50h.

11. The method for producing mesophase carbon microspheres according to claim 9, characterized in that: The reaction conditions for the condensation unit are controlled as follows: reaction temperature of 400℃~460℃, reaction pressure of 0.8MPa~3.0MPa, and residence time of 0.3h~24h.

12. The method for producing mesophase carbon microspheres according to claim 9, characterized in that: The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. The bottom oil is controlled to distill at a temperature of 300℃~420℃. The top oil is directly discharged from the unit or used as a diluent to be mixed with catalytic oil slurry for impurity removal and solidification treatment. The bottom oil is recycled back to be separated together with the liquid phase stream obtained in step (1).

13. The method for producing mesophase carbon microspheres according to claim 12, characterized in that: The bottom oil 5% distillation temperature is controlled at 330℃~370℃.

14. The method for producing mesophase carbon microspheres according to claim 9, characterized in that: A condensation catalyst is added during the condensation reaction, and the condensation reaction is carried out under the action of the condensation catalyst. The condensation catalyst includes a support and an active component. The support is one or more of kaolin, montmorillonite, alumina, and silica-containing alumina. The active component is at least one of oxides of Group IVB and / or Group VIB metals. The content of the active component is 0.1wt% to 50wt% based on the weight of the catalyst.

15. The method for producing mesophase carbon microspheres according to claim 14, characterized in that: The support is alumina, and the content of active components is 5wt% to 25wt% based on the weight of the catalyst.

16. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The tail oil discharge device in step (1) is used as a raw material for the production of low-sulfur petroleum coke.

17. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The operating conditions of the cracking unit in step (2) are controlled as follows: reaction pressure is 0.2MPa~1.0MPa, reaction temperature is 420℃~490℃, and residence time is 0.1h~3h.

18. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: During the cracking reaction, a carrier gas is introduced, which is one or more of water vapor, nitrogen, and inert gases; the mass ratio of the intermediate fraction to the carrier gas is 100:0.1 to 100:

20.

19. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: During the cracking reaction, a carrier gas, which is water vapor, is introduced; the mass ratio of the intermediate fraction to the carrier gas is 100:1 to 100:

8.

20. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: In step (2), the mass ratio of the second material stream to the first material stream is 1:9 to 8:

2.

21. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: In step (2), the mass ratio of the second material stream to the first material stream is 3:7 to 7:

3.

22. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The operating conditions of the first heat treatment unit in step (3) are as follows: reaction pressure is 1-10 MPa, reaction temperature is 420-460℃, and treatment time is 8-20 h.

23. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The operating conditions of the first heat treatment unit in step (3) are as follows: reaction pressure is 5-10 MPa, reaction temperature is 440-460℃, and treatment time is 12-16 h.

24. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The inert atmosphere in step (3) is one or more of nitrogen, helium, neon, argon, krypton, and xenon.

25. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The inert atmosphere in step (3) is nitrogen.

26. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The particle size of the first solid flow obtained after crushing in step (3) is no greater than 100 micrometers.

27. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The weight ratio of the first solid phase flow to the first solvent in step (4) is 1:10 to 50.

28. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The weight ratio of the first solid phase stream to the first solvent in step (4) is 1:10 to 20.

29. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The weight ratio of the first solid phase flow to the silicone oil in step (4) is 1:1 to 10.

30. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The weight ratio of the first solid phase flow to the silicone oil in step (4) is 1:5 to 10.

31. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: In step (4), the first solvent is at least one of petroleum ether, methyl ethyl ketone, and carbon tetrachloride.

32. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: In step (4), the first solvent is petroleum ether.

33. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The solid first material obtained in step (3) in step (4) is mixed evenly with the first solvent, and then mixed evenly with silicone oil before undergoing a second heat treatment.

34. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The silicone oil mentioned in step (4) is one or more of the following: methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen silicone oil, hydroxy hydrogen silicone oil, and cyanide silicone oil.

35. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The silicone oil mentioned in step (4) is phenyl silicone oil.

36. The method for producing mesophase carbon microspheres according to claim 1, characterized in that: The second heat treatment in step (4) consists of two stages. The first stage heat treatment temperature is 60-90℃, the heating rate is 1-5℃ / min, and the heat treatment time is 5-30min. The second stage heat treatment temperature is 260-290℃, the heating rate is 5-10℃ / min, and the heat treatment time is 5-10min.

37. A production system for mesophase carbon microspheres implementing the production method of any one of claims 1-36, comprising: The hydrogenation unit is used to receive hydrogen and catalytic slurry, and a hydrogenation reaction takes place under the action of a hydrogenation catalyst; The separation unit is used to receive the hydrogenation reaction effluent from the hydrogenation unit and separate it into a gaseous stream and a liquid stream. The fractionation unit receives the liquid stream from the separation unit and fractionates it to obtain light fraction, middle fraction and tail oil. The middle fraction is further divided into a first stream and a second stream. The cracking unit receives the first stream of material from the fractionation unit, and the cracking products obtained after the reaction are recycled back to the fractionation unit and processed together with the liquid stream obtained from the separation unit. The first heat treatment unit is used to receive the second stream from the fractionation unit and perform the first heat treatment in the presence of an inert atmosphere. The product of the first heat treatment is crushed to obtain a solid first stream. The second heat treatment unit is used to receive the first solid-phase feed stream, the first solvent, and the silicone oil from the first heat treatment unit, mix them evenly, and then perform a second heat treatment. After cooling, the mixture is separated, washed, and dried to obtain mesophase carbon microspheres.

38. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The system includes a purification unit. The catalytic slurry first enters the purification unit for desolidification treatment. The purification unit adopts one or more of the following methods: filtration, centrifugal sedimentation, flocculation sedimentation, and vacuum distillation.

39. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The hydrogenation unit is equipped with at least one hydrogenation reactor, which is selected from one or more of the following: fluidized bed reactor, suspended bed reactor, and fixed bed reactor.

40. The production system for mesophase carbon microspheres according to claim 39, characterized in that: The hydrogenation reactor is a fixed-bed reactor.

41. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The fractionation unit includes at least one fractionation tower, which is either a packed tower or a plate tower.

42. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The cracking unit is equipped with at least one reactor, which is one or more of the following: tubular reactor, tower reactor, and tank reactor.

43. The production system for mesophase carbon microspheres according to claim 42, characterized in that: The reactor is a tower reactor.

44. The production system for mesophase carbon microspheres according to claim 37, characterized in that: It includes a condensation unit for receiving light fractions from a fractionation unit. The reaction products obtained from the condensation reaction are separated to obtain top oil and bottom oil. The condensation unit employs at least one of a tubular reactor, a tower reactor, and a tank reactor.

45. The production system for mesophase carbon microspheres according to claim 44, characterized in that: The condensation unit uses a tower reactor.

46. ​​The production system for mesophase carbon microspheres according to claim 37, characterized in that: The first heat treatment unit employs at least one of a tower reactor or a tank reactor.

47. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The first heat treatment unit uses a tower reactor.

48. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The second heat treatment unit employs at least one of a tower reactor or a tank reactor.

49. The production system for mesophase carbon microspheres according to claim 37, characterized in that: The second heat treatment unit uses a tower reactor.

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