An isotropic coke and its preparation method

Abstract

This invention provides an isotropic coke and its preparation method. The preparation method includes: selectively hydrotreating a feedstock oil to obtain hydrotreated residue oil; adding additives, including crosslinking agents and / or coal tar-like substances, to the feedstock oil or hydrotreated residue oil; when the additives include crosslinking agents, reacting under an acid catalyst to obtain modified oil; when the additives only include coal tar-like substances, mixing to obtain mixed oil; solvent deasphalting the modified oil or mixed oil to obtain deasphalted oil and deoiled pitch; and coking the deoiled pitch to obtain isotropic coke. The isotropic coke of this invention is prepared by this method. The preparation method of the isotropic coke of this invention has strong raw material applicability, high added value, simple process, and is easy to operate, and can produce high-quality isotropic coke.

Description

Technical Field

[0001] This invention relates to an isotropic coke and its preparation method, belonging to the field of carbon materials technology. Background Technology

[0002] The performance of carbon products largely depends on the structure and properties of the aggregate. Isotropic coke, with its unique properties, plays a crucial role in the carbon industry, just like anisotropic coke.

[0003] The stability and safety of isotropic coke products are difficult to guarantee, which seriously restricts the development of the special carbon industry and industries such as nuclear industry and aerospace industry.

[0004] Isotropic coke generally refers to coke with a fine-grained mosaic optical structure, lacking a single orientation. This structure determines that the properties of the coke are the same in all directions, exhibiting macroscopic isotropic properties. Taking the coefficient of thermal expansion as an example, isotropic coke is consistent in all directions, unlike anisotropic coke such as needle coke, which varies in all directions, with the lowest coefficient of thermal expansion along the axis parallel to the needle-like texture. Isotropic coke exhibits anisotropy at the micron or even nanometer scale and can be graphitized to form graphite microcrystals, while macroscopically it is isotropic overall. Therefore, isotropic coke is very suitable as an aggregate for isotropic graphite. Studies have shown that in the manufacturing process of isotropic graphite, the use of asphalt binders and graphitization treatment results in the absence of orientation in the distribution of microcrystals within the graphite, having little impact on the degree of isotropy. However, if the isotropy of the coke particles is very high, even using compression molding, the degree of isotropy (also known as the anisotropy coefficient) can be controlled within 1.1. The microstructures of ordinary pitch coke and petroleum coke are anisotropic. To produce isotropic graphite from anisotropic coke, a cumbersome and lengthy production process is required. However, using isotropic coke to produce isotropic graphite products has significant advantages. Its high strength, high density, and unique isotropy have laid the technological foundation for the production of isotropic graphite, making it particularly suitable for manufacturing high-end specialty graphites, such as isotropic nuclear graphite.

[0005] CN114525153A discloses a method for preparing isotropic coke for lithium-ion battery anode materials. The method includes the following steps: removing quinoline-insoluble matter from aromatic oil via vacuum flash evaporation to obtain flash oil; mixing the flash oil with a nucleating agent in a specific ratio and performing a polymerization reaction to obtain polymerized oil; coking the polymerized oil and then naturally cooling it in a nitrogen atmosphere to obtain isotropic coke. This method employs a three-step process to achieve integrated preparation of isotropic coke. By adding a nucleating agent, it ensures the easy formation of mesophase microspheres during the preparation process, while the fusion between microspheres is prevented by the addition of the nucleating agent, ensuring a large number and uniform distribution of mesophase microspheres. Simultaneously, the micron-sized nucleating agent promotes the formation of small plate structures, resulting in isotropic coke exhibiting a coexistence of mosaic and small plate structures at the microscopic level. However, the raw materials for this method are limited to aromatic oils, and flash evaporation is required to remove quinoline insolubles, which increases the operating cost. Moreover, isotropic coke has both mosaic and small-piece structures, with small-piece structures accounting for ≥50% and mosaic structures accounting for a low proportion.

[0006] CN103693635A discloses a method for preparing isotropic coke. This method uses coal tar as raw material, purifying it through solvothermal filtration. The refined coal tar is then oxidized, cross-linked, and condensed with resin to obtain oxidized pitch. The oxidized pitch is then subjected to delayed coking and calcination to prepare isotropic coke. This method has advantages such as short processing time, high yield, no need to remove catalyst residues, and low environmental pollution. However, while this method increases the degree of cross-linking of the coal tar raw material through oxidation, and the process is simple and the raw materials are readily available, the oxidation depth is uncontrollable, the reaction control window is narrow, and the oxidation process varies significantly depending on the raw material, which is detrimental to the stability of the isotropic coke quality.

[0007] CN1306070A discloses a method for preparing isotropic coke using coal tar or petroleum residue distillate as raw material. The method involves placing the coal tar or petroleum residue distillate in a reactor and heating it to 120°C. Stirring is initiated, and oxygen-containing gas is introduced at a flow rate of 5-45 L / h per 100 g of raw material. The reaction temperature is 260-430°C, and after reaching the reaction temperature, the temperature is maintained for 5-15 hours to obtain oxidized coal tar or petroleum residue distillate. The oxidized coal tar or petroleum residue distillate is then coked at 460-500°C under nitrogen protection at a pressure of 0.1-1 MPa to generate isotropic coke. This method is simple and easy to operate, and the prepared isotropic coke exhibits a fine or very fine mosaic structure. However, this method also employs an oxidation process to increase the steric hindrance of the raw material, forming more mosaic structures, which also presents a problem of poor controllability.

[0008] CN105087033A discloses a method for preparing isotropic coke. The method includes the following steps: a) adding a pitch-like substance containing high levels of quinoline insolubles and high levels of toluene insolubles to pitch and mixing thoroughly; b) heat-treating the product obtained in step a) under vacuum at 300-400℃ to remove light components, obtaining pitch with a softening point of 100-200℃; c) carbonizing the pitch product obtained in step b) under pressure at 400-500℃ to obtain isotropic raw coke; d) calcining the isotropic raw coke obtained in step c) at 1100-1400℃ to obtain the isotropic coke product. This method can improve economic efficiency by utilizing waste from needle coke production. However, the method promotes the formation of mosaic structures by adding pitch-like substances with high levels of quinoline and toluene insolubles, highlighting compatibility issues with the raw materials.

[0009] CN115651689A discloses a method for producing homogeneous coke and needle coke using soft bitumen. This method uses the same raw material and employs a solvent sedimentation method combined with a "dual-group, dual-tower continuous extraction" separation technology to pretreat the soft bitumen. The pretreated raw material is then subjected to coking operations to obtain different types of raw coke, enabling the production of two carbon products with different properties and applications on the same production line: homogeneous coke with an embedded structure and needle coke with a streamlined structure. However, this method is limited to using soft bitumen as the raw material, and achieving high performance for both homogeneous coke and needle coke products is quite challenging.

[0010] Therefore, developing a method that is highly adaptable to raw materials and can produce high-quality isotropic coke remains one of the urgent problems to be solved in this field. Summary of the Invention

[0011] To address the aforementioned technical problems, the present invention aims to provide an isotropic coke and its preparation method. The method of the present invention has strong raw material applicability, high added value, and can produce high-quality isotropic coke.

[0012] To achieve the above objectives, a first aspect of the present invention provides a method for preparing an isotropic foil, comprising the following steps:

[0013] (1) Selectively hydrogenate the feedstock oil to obtain hydrogenated residue oil; add additives to the feedstock oil or hydrogenated residue oil, the additives including crosslinking agents and / or coal tar substances; when the additives include crosslinking agents, react under the action of an acid catalyst to obtain modified oil; when the additives only include coal tar substances, mix them to obtain mixed oil.

[0014] (2) The modified oil or the mixed oil is subjected to solvent deasphalting to obtain deasphalted oil and deoiled asphalt;

[0015] (3) The deoiled pitch is coked to obtain isotropic coke.

[0016] In the above method, preferably, in step (1), the feed oil includes one or a combination of several of the following: catalytic slurry oil, ethylene tar, furfural extract oil, heavy aromatic oil, coking wax oil, catalytic cycle oil, deoiled asphalt, atmospheric residue, and vacuum residue. More preferably, the feed oil is a feed oil that has undergone deashing treatment.

[0017] In the above method, preferably, in step (1), the sulfur mass content / residual carbon mass content in the feed oil and the hydrogenated residue oil to be added to the additive is <0.018, and the ash mass content / residual carbon mass content is <0.008.

[0018] In the above method, preferably, in step (1), the crosslinking agent includes one or a combination of several of terephthalic acid, terephthaloyl chloride, and paraformaldehyde. Paraformaldehyde is preferably trioxymethylene.

[0019] In the above method, preferably, in step (1), the mass content of naturally occurring quinoline insolubles in the coal tar-like substances is 6% or more. The coal tar-like substances include, but are not limited to, one or a combination of several of low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar.

[0020] In the above method, preferably, in step (1), the amount of additive added is 5-30% based on the total mass of the raw material oil or hydrogenated residue oil as 100%.

[0021] In the above method, preferably, in step (1), the acid catalyst comprises a solid acid catalyst. More preferably, the solid acid catalyst comprises one or a combination of several of the following: zeolite molecular sieves, immobilized liquid acids, cation exchange resins, metal oxides, metal sulfides, metal salts, composite metal oxides, carbon-based solid acids, and solid organic acids. The cation exchange resin preferably comprises a sulfonic acid-based cation exchange resin; the solid organic acid preferably comprises p-toluenesulfonic acid.

[0022] In the above method, preferably, in step (1), the reaction under the action of an acid catalyst specifically includes: feeding a mixture of feedstock oil or hydrogenated residue oil and additives including crosslinking agents into a reactor packed with a solid acid catalyst for reaction, with a reaction temperature of 80-160°C and a residence time of 5-30 min, to obtain modified oil.

[0023] In the above method, preferably, step (2) specifically includes: allowing the modified oil or the mixed oil to enter the extraction tower and the settling tower for extraction and separation, the top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component of the tower is recovered by solvent to obtain deoiled asphalt, thus completing solvent deasphalting.

[0024] In the above method, preferably, in step (2), the conditions for solvent deasphalting include: the solvent used includes one or a combination of several of the following: C3-C6 straight-chain and / or branched-chain alkanes, condensate oil, light gasoline and light naphtha; the bottom temperature of the extraction tower is 50℃-200℃, the top temperature is 60-210℃, the solvent-to-oil ratio is (4-10):1 (volume ratio), the pressure is 2.8-4.2MPa, and the residence time is 5-40min; the bottom temperature of the settling tower is 60-210℃, the top temperature is 70-220℃, the pressure is 2.8-4.2MPa, and the residence time is 6-20min.

[0025] In the above method, preferably, in step (2), the yield of the deoiled bitumen is 40%-90%.

[0026] In the above method, preferably, in step (2), based on the total mass of the deoiled bitumen as 100%, the asphalt content is 10-55%, the resin content is 5-30%, the saturated hydrocarbon content is 0-20%, and the aromatic hydrocarbon content is 20-40%.

[0027] In the above method, preferably, in step (3), the coking reaction temperature is 470-570℃ and the reaction pressure is 0.1-6MPa.

[0028] A second aspect of the present invention provides an isotropic focal plane, which is prepared by the above-described method for preparing isotropic focal plane.

[0029] According to a specific embodiment of the present invention, preferably, the optical structure of the isotropic focal point is a 100% damascene structure, and its isotropic degree (CTE ratio) is 1.07 or less.

[0030] This invention provides an isotropic coke and its preparation method. The method employs a modification-solvent deasphalting process, achieving high-quality isotropic coke with a 100% mosaic structure while ensuring strong applicability of raw materials. The additives used in modifying the feedstock oil or hydrotreated residue include crosslinking agents and / or coal tar-like substances with structures significantly different from the oil-based feedstock. After reacting the feedstock oil or hydrotreated residue with the additives including the crosslinking agent under a solid acid catalyst, highly cracking-active components are effectively removed, yielding modified oil. Mixing the feedstock oil or hydrotreated residue with additives containing only coal tar-like substances yields a mixed oil. Solvent deasphalting of the modified oil or mixed oil yields deasphalted oil that can be used as feedstock for catalytic cracking and hydrocracking, and even as feedstock for high-end carbon materials such as needle coke. The resulting deasphalted pitch is rich in highly active polycyclic aromatic hydrocarbons, which, after coking, can produce high-quality isotropic coke. The isotropic coke prepared by this invention can be used to produce energy storage materials and specialty graphite products.

[0031] The technical solution of the present invention has at least the following beneficial effects:

[0032] 1. In terms of applicability, the raw materials for producing homogeneous coke generally require low sulfur and inorganic impurity content. This method is applicable not only to low-sulfur and low-ash raw materials but also to raw materials with high sulfur and high ash content. High-sulfur raw materials, after hydrogenation treatment, can ensure that the sulfur content of homogeneous coke is below 0.5% by controlling the sulfur content / residual carbon content ratio below 0.018 and the ash content / residual carbon content ratio below 0.008. Currently, high-sulfur crude oil accounts for more than half of the supply, and the Middle East, where crude oil production is most concentrated, also mainly uses high-sulfur crude oil. With the deterioration of crude oil resources, refineries will increasingly face the problem of processing high-sulfur raw materials. Therefore, this method has high adaptability.

[0033] 2. In terms of yield, the modified-solvent deasphalting process of this invention effectively removes components with high cracking activity, significantly increases the asphaltenes content in the deoiled asphalt, and reduces the aromatic hydrocarbon content. It has the effect of increasing molecular structure and increasing effective components, resulting in deoiled asphalt with high asphaltenes and resin content and low aromatic hydrocarbon and saturated hydrocarbon content. The yield of deoiled asphalt is high and it is suitable for the production of homogeneous coke.

[0034] 3. From an economic perspective, the method of this invention actually utilizes the heaviest components of crude oil—rubber and asphalt—in a high-value-added way. In refineries, the main use of asphalt is to blend road asphalt, which costs about 4,000 yuan. At the same time, the price of coke is about 6,000 yuan. Furthermore, high-value gasoline and diesel can be produced during the coking process.

[0035] In summary, the method for preparing isotropic coke of the present invention has strong applicability to raw materials, high added value, and a simple and easy-to-operate process. It can effectively remove components with high cracking activity and enrich highly active fused ring components, producing high-quality isotropic coke with a 100% mosaic structure and an isotropy of less than 1.07, with a high yield. Simultaneously, the remaining deasphalted oil can be used as a feedstock for high-end carbon materials such as needle coke or in processes such as catalytic cracking and hydrocracking, improving the comprehensive utilization rate and added value of the raw materials. Therefore, the method of the present invention can provide refineries with an effective way to utilize heavy feedstocks with high added value and produce high-end carbon materials, achieving complete utilization of crude oil. Attached Figure Description

[0036] Figure 1 A process flow diagram of the preparation method of isotropic coke provided for a specific embodiment of the present invention.

[0037] Figure 2 A polarizing microscope image of an isotropic focal plane provided in Example 1.

[0038] Figure 3 A polarizing microscope image of an isotropic focal plane provided for Comparative Example 1. Detailed Implementation

[0039] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0040] According to a specific embodiment of the present invention, the present invention provides a method for preparing isotropic coke, such as... Figure 1 As shown, it includes the following steps:

[0041] (1) Selectively hydrogenate the feedstock oil to obtain hydrogenated residue oil; add additives to the feedstock oil or hydrogenated residue oil, the additives including crosslinking agents and / or coal tar substances; when the additives include crosslinking agents, react under the action of an acid catalyst to obtain modified oil; when the additives only include coal tar substances, mix them to obtain mixed oil.

[0042] (2) The modified oil or the mixed oil is subjected to solvent deasphalting to obtain deasphalted oil and deoiled asphalt;

[0043] (3) The deoiled pitch is coked to obtain isotropic coke.

[0044] In some embodiments, in step (1), the feedstock oil includes one or a combination of several of the following: catalytic slurry oil, ethylene tar, furfural extract oil, heavy aromatics oil, coking wax oil, catalytic cycle oil, deoiled pitch, atmospheric residue, and vacuum residue. Preferably, the feedstock oil is a feedstock oil that has undergone deashing treatment. The present invention does not impose special limitations on the deashing process and can employ existing deashing processes.

[0045] In some embodiments, in step (1), the sulfur mass content / carbon mass content in the feed oil to be added and the hydrogenated residue oil is <0.018, and the ash mass content / carbon mass content is <0.008. This invention allows for the direct addition of additives to feed oils that meet the above indicators. If the feed oil does not meet the above indicators, hydrogenation treatment is performed. This invention does not impose special restrictions on the hydrogenation process, including but not limited to fixed-bed hydrogenation, fluidized-bed hydrogenation, and suspended-bed hydrogenation, as long as the prepared hydrogenated residue oil meets the above indicators.

[0046] In some embodiments, in step (1), the crosslinking agent includes one or a combination of several of terephthalic acid, terephthaloyl chloride, and paraformaldehyde. Paraformaldehyde is preferably trioxymethylene.

[0047] In some embodiments, in step (1), the mass content of naturally occurring quinoline insolubles in the coal tar-like substances is 6% or more. The coal tar-like substances include, but are not limited to, one or a combination of several of low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar.

[0048] In some embodiments, in step (1), the amount of additive added is 5-30% based on the total mass of the feedstock oil or hydrotreated residue oil as 100%.

[0049] In some embodiments, in step (1), the acid catalyst comprises a solid acid catalyst. Preferably, the solid acid catalyst comprises one or a combination of several of the following: zeolite molecular sieves, supported liquid acids, cation exchange resins, metal oxides, metal sulfides, metal salts, composite metal oxides, carbon-based solid acids, and solid organic acids. The cation exchange resin preferably comprises a sulfonic acid-based cation exchange resin; the solid organic acid preferably comprises p-toluenesulfonic acid.

[0050] In some embodiments, in step (1), the reaction under the action of an acid catalyst specifically includes: feeding a mixture of feedstock oil or hydrogenated residue oil and additives including a crosslinking agent into a reactor packed with a solid acid catalyst for reaction, with a reaction temperature of 80-160°C and a residence time of 5-30 min, to obtain modified oil.

[0051] In some embodiments, step (2) specifically includes: introducing the modified oil or the mixed oil into an extraction tower and a settling tower for extraction and separation; recovering the solvent from the top component of the tower to obtain deasphalted oil; and recovering the solvent from the bottom component of the tower to obtain de-oiled asphalt, thus completing solvent deasphalting. The system used in the solvent deasphalting process of the present invention, including an extraction tower, a settling tower, a solvent recovery tower, etc., can be a system in the prior art, and the present invention does not impose any special restrictions on its structure.

[0052] In some embodiments, in step (2), the conditions for solvent deasphalting include: the solvent used includes one or a combination of several of C3-C6 straight-chain and / or branched-chain alkanes, condensate oil, light gasoline and light naphtha; the bottom temperature of the extraction tower is 50℃-200℃, the top temperature is 60-210℃, the solvent-to-oil ratio is (4-10):1 (volume ratio), the pressure is 2.8-4.2MPa, and the residence time is 5-40min; the bottom temperature of the settling tower is 60-210℃, the top temperature is 70-220℃, the pressure is 2.8-4.2MPa, and the residence time is 6-20min.

[0053] In some embodiments, in step (2), the yield of the deoiled bitumen is 40%-90%.

[0054] In some embodiments, in step (2), based on the total mass of the deoiled bitumen as 100%, the asphalt content is 10-55%, the resin content is 5-30%, the saturated hydrocarbon content is 0-20%, and the aromatic hydrocarbon content is 20-40%.

[0055] In some embodiments, in step (3), the coking reaction temperature is 470-570°C and the reaction pressure is 0.1-6 MPa. The coking process of the present invention includes, but is not limited to, delayed coking, batch coking, or fluidized bed coking, with fluidized bed coking being preferred.

[0056] like Figure 1 As shown, in this invention, the feedstock oil is selected for hydrotreating based on its sulfur and ash content. Low-sulfur, low-ash feedstock oil or hydrotreated residue oil meeting low-sulfur, low-ash requirements is modified by adding additives including crosslinking agents and / or coal tar-like substances. When the additives include crosslinking agents, the reaction occurs under an acid catalyst to obtain modified oil. When the additives only include coal tar-like substances, the mixture yields a blended oil. Then, the modified oil or blended oil undergoes solvent deasphalting. The resulting deasphalted oil can be used for catalytic cracking, hydrocracking, or as a raw material for carbon materials such as needle coke. The deasphalted pitch is used as a coking feedstock to produce homogeneous coke. The resulting homogeneous coke can be calcined and processed through different steps to produce special graphite or energy storage anode materials.

[0057] In the following embodiments and comparative examples, the mosaic structure and isotropic degree of the isotropic focus (green focus) were tested by the following methods.

[0058] 1. The isotropic coke (raw coke) was tested by polarizing microscope. The specific steps were as follows: the coke sample was crushed to a particle size of about 1 mm, cured with resin, polished and then the microstructure was observed.

[0059] 2. Isotropic coke (green coke) is formed into a volume of 1 dm using a small vibration molding machine. 3 After the coke block is calcined in a calcining furnace at 1300℃ for 2 hours, cylinders of the same diameter are drilled in its horizontal and vertical directions using a hollow drill, and their CTE is measured. The ratio of the two is the CTE ratio, which is the degree of isotropy.

[0060] Example 1

[0061] This embodiment provides a method for preparing isotropic foam, which includes the following steps:

[0062] (1) Using ethylene tar from a certain refinery as raw material, the properties of which are shown in Table 1; adding 10% of the total mass of the raw material to the raw material, and the resulting mixture is fed into a reactor packed with a solid p-toluenesulfonic acid catalyst for reaction at a reaction temperature of 160°C and a residence time of 5 min to obtain modified oil.

[0063] (2) The modified oil is fed into an extraction tower and a settling tower for extraction and separation. The top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component is recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting include: propane as solvent, solvent-to-oil ratio of 6, bottom temperature of the extraction tower of 80°C, top temperature of the extraction tower of 90°C, pressure of 3.5 MPa, and residence time of 20 min; bottom temperature of the settling tower of 90°C, top temperature of the settling tower of 100°C, pressure of 3.5 MPa, and residence time of 15 min. The properties of the obtained de-oiled asphalt are shown in Table 1.

[0064] (3) The deoiled bitumen was subjected to batch coking at a reaction temperature of 490℃, a pressure of 0.3MPa, and a time of 10h to obtain isotropic coke, the properties of which are shown in Table 2.

[0065] Table 1 Properties of ethylene tar and deoiled pitch

[0066]

[0067]

[0068] Table 2 Properties of Isotropic Foam

[0069]

[0070] The isotropic polarizing microscope images provided in this embodiment are as follows: Figure 2 As shown above, the optical structure of the isotropic focal plane provided in this embodiment is a 100% tessellation structure, and its isotropic degree (CTE ratio) is 1.02.

[0071] Comparative Example 1

[0072] This comparative example provides a method for preparing isotropic char, which includes the following steps:

[0073] Using ethylene tar from a certain refinery as feedstock, its properties are shown in Table 3. The ethylene tar was subjected to batch coking at a reaction temperature of 490℃, a pressure of 0.3MPa, and a time of 10h to obtain isotropic coke, the properties of which are shown in Table 4.

[0074] Table 3 Properties of Ethylene Tar

[0075] Analysis Project Ethylene tar Yield, % 100 Carbon residue,% 12.73 Ash content, % 0.0148 sulfur,% 0.118 Four components, % Saturation fraction, % 0.2 Aromatics, % 68.08 Gel, % 4.53 Asphalt, % 27.19

[0076] Table 4 Properties of Isotropic Foam

[0077]

[0078] The isotropic polarizing microscope images provided in this comparative example are as follows: Figure 3 As shown above, the optical structure of the isotropic focal plane provided in this comparative example is not a 100% tessellation structure, but also has a wide-area structure, with an isotropic degree (CTE ratio) of 1.13.

[0079] Example 2

[0080] This embodiment provides a method for preparing isotropic foam, which includes the following steps:

[0081] (1) A catalytic oil slurry that has undergone deashing treatment in a certain refinery was used as the feed oil, and its properties are shown in Table 5. 5% of the total mass of the feed oil was added to the feed oil, and the resulting mixture was fed into a reactor packed with sulfonic acid-based cation exchange resin catalyst for reaction. The reaction temperature was 140°C and the residence time was 10 min to obtain modified oil.

[0082] (2) The modified oil is fed into an extraction tower and a settling tower for extraction and separation. The top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component is recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting include: butane as solvent, solvent-to-oil ratio of 4, bottom temperature of the extraction tower of 90°C, top temperature of the extraction tower of 98°C, pressure of 4.2 MPa, and residence time of 5 min; bottom temperature of the settling tower of 93°C, top temperature of the settling tower of 100°C, pressure of 4.2 MPa, and residence time of 6 min. The properties of the obtained de-oiled asphalt are shown in Table 5.

[0083] (3) The deoiled bitumen was subjected to delayed coking at a reaction temperature of 500℃, a pressure of 0.3MPa, and a time of 24h to obtain isotropic coke, the properties of which are shown in Table 6.

[0084] Table 5 Properties of catalytic slurry and de-oiled bitumen after deashing treatment

[0085]

[0086]

[0087] Table 6 Properties of Isotropic Foam

[0088]

[0089] It can be seen that the optical structure of the isotropic focal plane provided in this embodiment is a 100% damascene structure, and its isotropic degree (CTE ratio) is 1.03.

[0090] Comparative Example 2

[0091] This comparative example provides a method for preparing isotropic char, which includes the following steps:

[0092] (1) A catalytic oil slurry that has undergone deashing treatment at a certain refinery was used as the feed oil, the properties of which are shown in Table 7. The feed oil was fed into an extraction tower and a settling tower for extraction and separation. The top component of the tower was recovered by solvent to obtain deasphalted oil, and the bottom component was recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting included: butane as solvent, solvent-to-oil ratio of 4, bottom temperature of the extraction tower of 90°C, top temperature of the extraction tower of 98°C, pressure of 4.2 MPa, and residence time of 5 min; bottom temperature of the settling tower of 93°C, top temperature of the settling tower of 100°C, pressure of 4.2 MPa, and residence time of 6 min. The properties of the obtained de-oiled asphalt are shown in Table 7.

[0093] (2) The deoiled bitumen was subjected to delayed coking at a reaction temperature of 500℃, a pressure of 0.3MPa, and a time of 24h to obtain isotropic coke, the properties of which are shown in Table 8.

[0094] Table 7 Properties of catalytic slurry and de-oiled bitumen after deashing treatment

[0095] Analysis Project Catalytic slurry oil undergoing deashing treatment Deoiled Asphalt Yield, % 98 25 Carbon residue,% 23.72 30.16 Ash content, % 0.0163 0.09 sulfur,% 0.42 0.51 Four components, % Saturation fraction, % 22.35 10.05 Aromatics, % 30.55 21.81 Gel, % 31.48 22.52 Asphalt, % 15.62 45.62 Softening point, ℃ 189

[0096] Table 8 Properties of Isotropic Foam

[0097]

[0098] It can be seen that the optical structure of the isotropic focal plane provided in this comparative example is not a 100% tessellation structure, but also has a wide-area structure, and its isotropic degree (CTE ratio) is 1.10.

[0099] Example 3

[0100] This embodiment provides a method for preparing isotropic foam, which includes the following steps:

[0101] (1) Using high-sulfur and high-ash residue oil from a certain refinery as feedstock, the feedstock oil was hydrotreated to obtain hydrotreated residue oil, the properties of which are shown in Table 9. Trioxymethylene, accounting for 10% of the total mass of the hydrotreated residue oil, was added to the hydrotreated residue oil. The resulting mixture was fed into a reactor packed with a solid p-toluenesulfonic acid catalyst for reaction. The reaction temperature was 80°C and the residence time was 30 min to obtain modified oil, the properties of which are shown in Table 9.

[0102] (2) The modified oil is fed into an extraction tower and a settling tower for extraction and separation. The top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component is recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting include: pentane as solvent, solvent-to-oil ratio of 9, bottom temperature of the extraction tower of 50°C, top temperature of the extraction tower of 60°C, pressure of 3MPa, and residence time of 20min; bottom temperature of the settling tower of 60°C, top temperature of the settling tower of 70°C, pressure of 3MPa, and residence time of 10min. The properties of the obtained de-oiled asphalt are shown in Table 9.

[0103] (3) The deoiled bitumen was subjected to delayed coking at a reaction temperature of 500℃, a pressure of 0.3MPa, and a time of 24h to obtain isotropic coke, the properties of which are shown in Table 10.

[0104] Table 9 Properties of Hydrogenated Residue Oil, Modified Oil, and Deoiled Asphalt

[0105]

[0106]

[0107] Table 10 Properties of Isotropic Foam

[0108]

[0109] As can be seen from the above data, the optical structure of the isotropic focal plane provided in this embodiment is a 100% damascene structure, and its isotropic degree (CTE ratio) is 1.05.

[0110] Comparative Example 3

[0111] This comparative example provides a method for preparing isotropic char, which includes the following steps:

[0112] (1) Using high-sulfur and high-ash residue oil from a certain refinery as feedstock, the feedstock oil is hydrotreated to obtain hydrotreated residue oil, the properties of which are shown in Table 11. The hydrotreated residue oil is then fed into a viscosity-reducing reactor for viscosity-reducing cracking reaction at a temperature of 430℃, a pressure of 0.6MPa, a water injection rate of 5m%, and a reaction time of 10min. After viscosity reduction, the material is fed into a fractionation tower to separate dry gas, gasoline fraction, and viscosity-reduced heavy fraction oil.

[0113] (2) The reduced viscosity heavy component oil is fed into an extraction tower and a settling tower for extraction and separation. The top component is recovered by solvent to obtain deasphalted oil, and the bottom component is recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting include: pentane as solvent, solvent-to-oil ratio of 9, bottom temperature of extraction tower of 50°C, top temperature of extraction tower of 60°C, pressure of 3MPa, and residence time of 20min; bottom temperature of settling tower of 60°C, top temperature of settling tower of 70°C, pressure of 3MPa, and residence time of 10min. The properties of the obtained de-oiled asphalt are shown in Table 11.

[0114] (3) The deoiled bitumen was subjected to delayed coking at a reaction temperature of 500℃, a pressure of 0.3MPa, and a time of 24h to obtain isotropic coke, the properties of which are shown in Table 12.

[0115] Table 11 Properties of Hydrogenated Residue Oil and Deoiled Asphalt

[0116]

[0117]

[0118] Table 12 Properties of Isotropic Foam

[0119]

[0120] As can be seen from the data above, the optical structure of the isotropic focal plane provided in this comparative example is not a 100% tessellation structure, but also has a wide-area structure, with an isotropic degree (CTE ratio) of 1.29.

[0121] Example 4

[0122] This embodiment provides a method for preparing isotropic foam, which includes the following steps:

[0123] (1) Using high-sulfur and high-ash residue oil from a certain refinery as feedstock, the feedstock oil is hydrogenated to obtain hydrogenated residue oil, the properties of which are shown in Table 13; high-temperature coal tar (containing more than 6% of the mass of natural quinoline insoluble matter) is added to the hydrogenated residue oil, accounting for 30% of the total mass of the hydrogenated residue oil, and after mixing, a mixed oil is obtained, the properties of which are shown in Table 13.

[0124] (2) The mixed oil is fed into an extraction tower and a settling tower for extraction and separation. The top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component is recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting include: pentane as solvent, solvent-to-oil ratio of 10, bottom temperature of the extraction tower of 200°C, top temperature of the extraction tower of 210°C, pressure of 2.8 MPa, and residence time of 40 min; bottom temperature of the settling tower of 210°C, top temperature of the settling tower of 220°C, pressure of 2.8 MPa, and residence time of 20 min. The properties of the obtained de-oiled asphalt are shown in Table 13.

[0125] (3) The deoiled bitumen was subjected to delayed coking at a reaction temperature of 500℃, a pressure of 0.3MPa, and a time of 24h to obtain isotropic coke, the properties of which are shown in Table 14.

[0126] Table 13 Properties of Hydrogenated Residue Oil, Blended Oil, and Deoiled Asphalt

[0127]

[0128]

[0129] Table 14 Properties of Isotropic Foam

[0130]

[0131] As can be seen from the above data, the optical structure of the isotropic focal plane provided in this embodiment is a 100% damascene structure, and its isotropic degree (CTE ratio) is 1.07.

[0132] Example 5

[0133] This comparative example provides a method for preparing isotropic char, which includes the following steps:

[0134] (1) Using high-sulfur and high-ash residue oil from a certain refinery as feedstock, the feedstock oil is hydrogenated to obtain hydrogenated residue oil, the properties of which are shown in Table 15; high-temperature coal tar (containing more than 6% of the mass of natural quinoline insoluble matter) is added to the hydrogenated residue oil, accounting for 30% of the total mass of the hydrogenated residue oil, and after mixing, a mixed oil is obtained, the properties of which are shown in Table 15.

[0135] (2) The mixed oil is fed into an extraction tower and a settling tower for extraction and separation. The top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component is recovered by solvent to obtain de-oiled asphalt, thus completing solvent deasphalting. The conditions for solvent deasphalting include: pentane as solvent, solvent-to-oil ratio of 10, bottom temperature of the extraction tower of 200°C, top temperature of the extraction tower of 210°C, pressure of 2.8 MPa, and residence time of 40 min; bottom temperature of the settling tower of 210°C, top temperature of the settling tower of 220°C, pressure of 2.8 MPa, and residence time of 20 min. The properties of the obtained de-oiled asphalt are shown in Table 15.

[0136] (3) The deoiled bitumen was subjected to fluidized coking at a reaction temperature of 550°C, a pressure of 0.1 MPa, and a time of 10 s to obtain isotropic coke, the properties of which are shown in Table 16.

[0137] Table 15 Properties of Hydrogenated Residue Oil, Blended Oil, and Deoiled Asphalt

[0138] Analysis Project Hydrogenated residue oil Mixed oil Deoiled Asphalt Yield, % 90 117 43 Carbon residue,% 6.96 12.52 29.88 Ash content, % 0.05 0.09 0.14 sulfur,% 0.123 0.26 0.39 Four components, % Saturation fraction, % 35.7 26.22 15 Aromatics, % 32.62 30.63 32.2 Gel, % 24.9 23.12 24.1 Asphalt, % 6.78 20.03 28.7 Softening point, ℃ 150

[0139] Table 16 Properties of Isotropic Foam

[0140]

[0141] As can be seen from the above data, the optical structure of the isotropic focal plane provided in this embodiment is a 100% damascene structure, and its isotropic degree (CTE ratio) is 1.03.

[0142] As can be seen from the above embodiments and comparative examples:

[0143] (1) The isotropic coke produced in the various embodiments of the present invention exhibits a 100% mosaic structure in terms of optical structure, which is a significant improvement over the approximately 20-40% mosaic structure produced by direct coking. In addition, in terms of isotropy, the ratio of the thermal expansion coefficients in the transverse and longitudinal directions is below 1.07, which is a significant improvement over the approximately 1.2 of ordinary petroleum coke. Therefore, the method of the present invention can produce high-quality isotropic coke.

[0144] (2) The various embodiments of the present invention involve raw materials with different properties. Impurities in the raw materials can be removed and sulfur content reduced by hydrogenation treatment. The effective components of asphaltene can be increased by additive modification and solvent deasphalting process, thereby reducing the CTE ratio of isotropic coke and improving isotropy. The method of the present invention greatly improves the adaptability of isotropic coke raw materials and the yield of isotropic coke.

[0145] (3) Comparative Example 1 uses direct coking of feedstock oil, Comparative Example 2 does not undergo crosslinking modification but directly undergoes solvent deasphalting, and Comparative Example 3 does not undergo crosslinking modification but first uses viscosity-reducing cracking and then solvent deasphalting. The yield of isotropic coke in Comparative Examples 1 to 3 is significantly lower than that in Examples 1 to 3, and the prepared isotropic coke is not a 100% mosaic structure, and the ratio of its transverse and longitudinal thermal expansion coefficients is higher than that in Examples 1 to 3.

[0146] (4) As can be seen from Examples 4 and 5, fluidized coking tends to produce isotropic coke with excellent isotropy.

[0147] In summary, based on the research of the effective components of the raw materials for producing homogeneous coke, this invention selectively utilizes hydrogenation treatment and modification methods to effectively improve the raw material dependence of homogeneous coke, greatly enhance the quality of homogeneous coke products, and achieve the maximum high-value-added utilization of petroleum resources. The high-quality homogeneous coke produced using the method of this invention has broad application prospects in the fields of specialty graphite and lithium-ion battery energy storage.

Claims

1. A method for preparing isotropic coke, comprising the following steps: (1) Selectively hydrogenate the feedstock oil to obtain hydrogenated residue oil; add additives to the feedstock oil or hydrogenated residue oil, the additives including crosslinking agents and / or coal tar substances; when the additives include crosslinking agents, react under the action of an acid catalyst to obtain modified oil; when the additives only include coal tar substances, mix them to obtain mixed oil. (2) The modified oil or the mixed oil is subjected to solvent deasphalting to obtain deasphalted oil and deoiled asphalt; (3) The deoiled pitch is coked to obtain isotropic coke; In step (1), the sulfur mass content / carbon mass content in the feed oil and the hydrogenated residue oil to be added to the additive is <0.018, and the ash mass content / carbon mass content is <0.

008. Feed oil that meets the above indicators is directly added to the additive; if the feed oil does not meet the above indicators, the hydrogenation treatment is performed.

2. The method for preparing isotropic coke according to claim 1, wherein, In step (1), the feedstock oil includes one or a combination of several of the following: catalytic slurry oil, ethylene tar, furfural extract oil, heavy aromatic oil, coking wax oil, catalytic cycle oil, atmospheric residue oil, and vacuum residue oil.

3. The method for preparing isotropic coke according to claim 1 or 2, wherein, In step (1), the raw oil is a raw oil that has undergone deashing treatment.

4. The method for preparing isotropic coke according to claim 1, wherein, In step (1), the crosslinking agent includes one or a combination of several of terephthalic acid, terephthaloyl chloride and paraformaldehyde.

5. The method for preparing isotropic coke according to claim 1, wherein, In step (1), the mass content of natural quinoline insolubles in the coal tar-like substances is 6% or more.

6. The method for preparing isotropic coke according to claim 1, wherein, In step (1), the amount of additive added is 5-30% based on the total mass of the feedstock oil or hydrogenated residue oil as 100%.

7. The method for preparing isotropic coke according to claim 1, wherein, In step (1), the acid catalyst includes a solid acid catalyst.

8. The method for preparing isotropic coke according to claim 7, wherein, In step (1), the solid acid catalyst includes one or a combination of several of the following: zeolite molecular sieve, supported liquid acid, cation exchange resin, metal oxide, metal sulfide, metal salt, composite metal oxide, carbon-based solid acid and solid organic acid.

9. The method for preparing isotropic coke according to claim 7, wherein, In step (1), the reaction under the action of the acid catalyst specifically includes: feeding a mixture of feedstock oil or hydrogenated residue oil and additives including crosslinking agents into a reactor packed with solid acid catalyst for reaction, with a reaction temperature of 80-160℃ and a residence time of 5-30 min, to obtain modified oil.

10. The method for preparing isotropic coke according to claim 1, wherein, Step (2) specifically includes: allowing the modified oil or the mixed oil to enter the extraction tower and the settling tower for extraction and separation, the top component of the tower is recovered by solvent to obtain deasphalted oil, and the bottom component of the tower is recovered by solvent to obtain deoiled asphalt, thus completing solvent deasphalting.

11. The method for preparing isotropic coke according to claim 10, wherein, In step (2), the conditions for solvent deasphalting include: the solvent used includes one or a combination of several of the following: C3-C6 straight-chain and / or branched-chain alkanes, condensate oil, light gasoline and light naphtha; the bottom temperature of the extraction tower is 50℃-200℃, the top temperature is 60-210℃, the solvent-to-oil ratio is (4-10):1, the pressure is 2.8-4.2MPa, and the residence time is 5-40min; the bottom temperature of the settling tower is 60-210℃, the top temperature is 70-220℃, the pressure is 2.8-4.2MPa, and the residence time is 6-20min.

12. The method for preparing isotropic coke according to claim 1, wherein, In step (2), the yield of the deoiled bitumen is 40%-90%.

13. The method for preparing isotropic coke according to claim 1, wherein, In step (2), based on the total mass of the deoiled bitumen as 100%, the asphalt content is 10-55%, the resin content is 5-30%, the saturated hydrocarbon content is 0-20%, and the aromatic hydrocarbon content is 20-40%.

14. The method for preparing isotropic coke according to claim 1, wherein, In step (3), the coking reaction temperature is 470-570℃ and the reaction pressure is 0.1-6MPa.

15. An isotropic focal plane, which is prepared by the method of preparing the isotropic focal plane according to any one of claims 1-14.

16. The isotropic focal plane according to claim 15, wherein, The optical structure of the isotropic focal plane is a 100% mosaic structure, and its isotropic degree is below 1.07.

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