Method for co-producing mesophase pitch and isotropic pitch

Abstract

The invention relates to a method for co-producing mesophase pitch and isotropic pitch, which comprises the following steps: S1, carrying out pressurized copolymerization and fraction cutting on a raw material A, and fractionating gt; fractions B and lt at 400 DEG C; fraction C at 400 DEG C; s2, carrying out thermal polymerization on the fraction B to prepare mesophase pitch D and byproduct light oil E; s3, recycling the E, mixing the E with the C according to a specific proportion to serve as an isotropic asphalt modulation raw material, preparing isotropic asphalt F of different brands and byproduct light oil G through an air oxidation / negative pressure gas stripping process, and recycling G in the raw material A according to a specific proportion. According to the method, efficient utilization of the byproduct light oil in the asphalt preparation process is achieved, the asphalt yield is increased, and high-quality mesophase asphalt and isotropic asphalt of different brands can be prepared according to requirements.

Description

Technical Field

[0001] The invention relates to a method for co-producing mesophase asphalt and isotropic asphalt, belonging to the technical field of preparation of new carbon materials. Background Art

[0002] Mesophase asphalt is generally made of coal tar, petroleum asphalt and pure aromatics, and is prepared by direct thermal polycondensation, co-carbonization, catalytic thermal polycondensation and halogen induction. Mesophase asphalt has the advantages of high orientation, easy graphitization and high carbon yield. It is a key raw material for preparing high thermal conductivity asphalt-based carbon fibers, foamed carbon, and carbon / carbon composites. Isotropic asphalt is generally made of coal tar, ethylene tar, etc., and its softening point is increased by vacuum distillation and oxidation. It is mainly used in graphite negative electrode coating materials and general-grade asphalt carbon fibers.

[0003] The Chinese invention patent (CN113549466A) uses supercritical extraction equipment to distill and separate the raw materials to obtain asphalt components, which are then subjected to thermal polycondensation reaction and purification to ultimately obtain mesophase asphalt. However, the process for preparing asphalt with high mesophase content is complicated and inefficient.

[0004] The Chinese invention patent (CN113817501A) produces high-quality mesophase asphalt by cutting crude oil to make the product rich in polycyclic aromatic hydrocarbons, and then modifying it with supercritical water. However, the supercritical conditions are relatively harsh, requiring the use of ultra-high pressure, hydrogenation and other steps, and the process is complicated.

[0005] The Chinese invention patent (CN115873637A) separates different light fractions of heavy petroleum oil through a one-step nitrogen purge method, and the heavy bottom fraction is polymerized to form isotropic high softening point asphalt. There is a risk of coking due to long thermal history of a single kettle, and a small amount of intermediate phase is easily produced during the preparation of isotropic asphalt. Although the tail gas recovery device is mentioned to recycle the light component oil products, the actual application is not clear.

[0006] The Chinese invention patent (CN114106879B) uses petroleum slurry as raw material, obtains primary mesophase asphalt through high temperature and high pressure polymerization, and then separates the recovered waste oil slurry components by fraction distillation, recovers low-boiling point materials for secondary mesophase asphalt preparation, and obtains general-grade asphalt by hydrogenation treatment and high-temperature polymerization of high-boiling point materials. Although this method improves the utilization rate of petroleum slurry, it needs to add tetralin as a hydrogenation agent in the subsequent processing process, the process is relatively complicated, and there are certain safety hazards.

[0007] The Chinese invention patent (CN117264646A) uses heavy oil as raw material and adopts a three-step process of thermal polymerization-sedimentation-coking to co-produce mesophase asphalt and needle coke. However, there are problems such as uneven sedimentation and separation, making it difficult to obtain high-quality mesophase asphalt. In addition, the oil and gas are not recycled, resulting in a waste of resources.

[0008] The Chinese invention patent (CN114479895B) uses a centrifugal reaction separation device coupled with a distillation control reaction system to prepare intermediate phase asphalt and isotropic matrix asphalt through rotational polycondensation and tilted separation. However, the quality of the resulting product is difficult to control and the equipment structure is complex, making it difficult to realize industrialization.

[0009] At present, the preparation of mesophase asphalt or isotropic asphalt mostly uses independent systems, and the raw materials, processes and other systems are also quite different. At the same time, the intermittent polymerization or single preparation of mesophase asphalt or isotropic asphalt has a low yield and produces more than 70% of waste oil that needs to be treated. Summary of the invention

[0010] (I) Purpose of the invention

[0011] In view of this, the purpose of the present invention is to propose a method for co-producing mesophase asphalt and isotropic asphalt, which solves the problems raised in the above background.

[0012] (II) Technical solution

[0013] A method for co-producing mesophase asphalt and isotropic asphalt comprises the following steps:

[0014] S1 performs pressurized copolymerization and fraction cutting on raw material A to obtain fraction B with a temperature of more than 400°C and fraction C with a temperature of less than 400°C;

[0015] S2 obtains mesophase asphalt D and by-product light oil E by thermal polymerization of fraction B;

[0016] S3 recycles the by-product light oil E and mixes it with C in a specific ratio as a raw material for isotropic asphalt preparation, and prepares different grades of isotropic asphalt F and by-product light oil G through air oxidation / negative pressure stripping process, and G is recycled in raw material A in a specific ratio;

[0017] The method realizes the efficient utilization of by-product light oil in the asphalt preparation process, improves the asphalt yield, and can prepare high-quality mesophase asphalt and isotropic asphalt of different grades according to demand.

[0018] Preferably, the raw material A in S1 is a mixture of heavy aromatic oil and light oil G which is a by-product of the isotropic asphalt modulation process. The main properties of the heavy aromatic oil are: C / H value is 9-10, gum content is 10%-30%, asphaltene content is ≤1%, and fraction above 400°C is ≥60%.

[0019] Preferably, the pressurized copolymerization conditions described in S1 are as follows: an initial nitrogen pressure of 0.1-0.5 MPa, a pressure of ≤2 MPa, a material temperature of 380-400°C, and a constant temperature time of 5-10 h in the constant temperature stage, and the ratio of the fraction B > 400°C to the fraction C < 400°C described in S1 is mC:mB=1 / 4~2 / 3, wherein mB is the mass of the fraction C > 400°C, and mC is the mass of the fraction C < 400°C.

[0020] Preferably, the thermal polycondensation conditions in S2 are nitrogen atmosphere protection and 380° C. to 420° C.

[0021] Preferably, the mesophase asphalt D described in S2 can be prepared into different grades as required, which is mainly achieved by the different constant temperature times in claim 7.

[0022] Preferably, the by-product light oil E in S3 is mixed with the <400°C fraction C in a specific ratio as a raw material for isotropic asphalt modulation, and the specific ratio is mE / mC=3 / 4~1, wherein mE is the mass of the by-product light oil E, and mC is the mass of the <400°C fraction C.

[0023] Preferably, the air oxidation process in S3 is performed at a material temperature of 310-330°C and an oxygen content of 0.05-0.1 m 3 / (h·kg); negative pressure gas stripping process: material temperature 360-380℃, vacuum degree 10~15Kpa, nitrogen volume 0.005~0.01m 3 / (h·kg).

[0024] Preferably, the isotropic asphalt F described in S3 can be prepared into different grades as required, which is mainly achieved by the different constant temperature times in claim 9.

[0025] Preferably, the by-product light oil G in S3 is recycled into the raw material A in a specific ratio, and the specific ratio is mG / mA=1 / 10~1 / 5, where mG is the mass of the by-product light oil G and mA is the total mass of the raw material A.

[0026] It can be seen from the above technical solutions that this application has the following beneficial effects:

[0027] 1. The raw material used in the method provided by the present invention is low value-added by-product heavy aromatic oil as the main raw material for pretreatment compounding, which is rich in source and low in cost. Therefore, it can reduce resource waste and increase economic benefits.

[0028] 2. The method provided by the present invention, according to the difference in properties of light oil in the modulation stage of mesophase asphalt and isotropic asphalt, recycles them in specific proportions and compounding with isotropic asphalt modulation raw materials and heavy aromatic oil pretreatment raw materials, thereby achieving efficient utilization of by-product light oil in the asphalt modulation process and improving asphalt yield, and integrating the co-production of mesophase asphalt and isotropic asphalt equipment systems, and can simultaneously prepare high-quality mesophase asphalt and isotropic asphalt of different grades according to demand.

[0029] 3. The method provided by the present invention has a simple process, relatively low requirements on equipment, does not use catalysts or hydrogen donors that are difficult to remove, and basically no toxic substances are produced during the reaction, which is environmentally friendly and safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a process flow of a method for co-producing mesophase asphalt and isotropic asphalt according to the present invention;

[0031] Figure 2 This is a schematic diagram of the characterization of different grades of mesophase asphalt samples according to the present invention.

[0032] Figure 3 This is a schematic diagram of the characterization of isotropic asphalt samples of different grades according to the present invention.

[0033] In the figure: P1, P2, P3, P4, P5- pumps; E1, E2, E3, E4- heat exchangers; R1- pretreatment polymerization kettle; T1- pressure reducing cutting tower; R2- mesophase asphalt modulation kettle; R3- isotropic asphalt modulation kettle; V1- isotropic asphalt by-product light oil collection tank; V1- mesophase asphalt by-product light oil collection tank. DETAILED DESCRIPTION

[0034] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, and use. It should be understood that in all of these figures, the same or similar reference numerals indicate the same or similar parts and features. The various drawings only schematically represent the concepts and principles of the embodiments of the present disclosure, and do not necessarily show the specific dimensions and proportions of the various embodiments of the present disclosure. Specific parts in specific drawings may be exaggerated to illustrate the relevant details or structures of the embodiments of the present disclosure.

[0035] Embodiment 1:

[0036] exist Figure 1 In the reaction system shown, the heavy aromatic oil is a catalytic cracking oil slurry with a C / H value of 9.5, a gum content of 12%, an asphaltene content of 0.8%, and 70% of the fraction above 400°C. The by-product light oil G: heavy aromatic oil A = 1:10 is used as raw material, and 220 kg is added to the pretreatment polymerization reactor R1 through a metering pump.

[0037] The initial nitrogen pressure of the pretreatment polymerization reactor R1 is 0.2Mpa, and the pressure is controlled to be ≤2Mpa during the temperature increase and constant temperature stages. The material temperature is maintained at 395℃ for 6 hours, and after slowly unloading the pressure to normal pressure, the pressurized copolymerized material is transported to the pressure reducing cutting tower T1 for fraction cutting through the pump P1. By controlling the cutting process, 145kg of fraction B with a temperature of >400℃ and 70kg of fraction C with a temperature of <400℃ are distilled out.

[0038] After the decompression cutting was completed, 140 kg of fraction B was transported to the mesophase asphalt preparation kettle R2 by pump P3 for nitrogen thermal polycondensation. The nitrogen atmosphere was protected and the material temperature was kept constant at 400 ° C for 5 h, 10 h, 15 h, and 20 h. Samples were taken for the characterization of mesophase asphalt samples of different grades, as shown in Table 1. R2 prepared 72 kg of mesophase asphalt D. The by-product light oil E was 70 kg, which was used for R3 preparation and recycling.

[0039] Byproduct light oil E and fraction C below 400℃ were mixed in a ratio of 1:1 as 140 kg of isotropic asphalt preparation raw material and added into R3 isotropic asphalt preparation kettle. 3 / h, constant temperature for 5h and 8h, respectively, and samples were taken to characterize the isotropic asphalt samples of different grades, see Table 2; when the softening point of isotropic asphalt is ≥180℃, the negative pressure gas stripping process is used to increase the material temperature to 370℃ and keep the temperature constant, and the nitrogen volume is 1m 3 / h protection, vacuum degree -0.088Mpa, constant temperature 3h, 5h, 7h respectively sampling, characterization of different grades of isotropic asphalt samples, see Table 2. R3 modulation finally obtained 77kg isotropic asphalt F. The by-product light oil G is 60kg, which is used for R1 modulation and recycling.

[0040] Embodiment 2:

[0041] exist Figure 1 In the reaction system shown, the heavy aromatic oil is a catalytic cracking oil slurry with a C / H value of 9.6, a resin content of 16%, an asphaltene content of 0.9%, and 75% of the fraction above 400°C. The by-product light oil G: heavy aromatic oil A = 1:6 is used as raw material, and 280 kg is added to the pretreatment polymerization reactor R1 through a metering pump.

[0042] The initial nitrogen pressure of the pretreatment polymerization kettle R1 is 0.5Mpa, and the pressure is controlled to be ≤2Mpa during the temperature increase and constant temperature stage. The material temperature is maintained at 390℃ for 8 hours, and after slowly unloading the pressure to normal pressure, the pressurized copolymerized material is transported to the pressure reducing cutting tower T1 for fraction cutting through the pump P1. By controlling the cutting process, 200kg of fraction B with a temperature of >400℃ and 75kg of fraction C with a temperature of <400℃ are distilled out.

[0043] After the decompression cutting is completed, 200kg of fraction B is transported to the mesophase asphalt preparation kettle R2 through pump P3 for nitrogen thermal polycondensation, nitrogen atmosphere protection, material temperature 405℃ constant temperature 20h, and finally 100kg of mesophase asphalt D is obtained, with a softening point of 287℃, polarization content>98%, QI content<50%, which can be used as high-quality spinning asphalt raw material. The by-product light oil E is 95kg, which is used for R3 preparation and recycling.

[0044] Take 75kg of by-product light oil E and <400℃ fraction C in a ratio of 1:1 as 150kg of isotropic asphalt preparation raw material and add it into R3 isotropic asphalt preparation kettle. At a material temperature of 330℃ and an oxygen content of 15m 3 / h, constant temperature for 6h, the softening point of the isotropic asphalt is 185℃, and the negative pressure gas stripping process is used to increase the material temperature to 372℃ and keep the temperature constant. The nitrogen volume is 1m 3 / h protection, vacuum degree -0.088Mpa, constant temperature for 9h, finally 90kg of isotropic asphalt F was obtained, with a softening point of 272℃, which can be used as a general-grade asphalt-based carbon fiber raw material. The by-product light oil G is 55kg, which is used for R1 pretreatment and recycling.

[0045] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for co-producing mesophase asphalt and isotropic asphalt, characterized in that: The following steps are involved: S1 performs pressurized copolymerization and fraction cutting on raw material A to obtain fraction B with a temperature of more than 400°C and fraction C with a temperature of less than 400°C; S2 obtains mesophase asphalt D and by-product light oil E by thermal polymerization of fraction B; S3 recycles the by-product light oil E and mixes it with C in a specific ratio as a raw material for isotropic asphalt preparation, and prepares different grades of isotropic asphalt F and by-product light oil G through air oxidation / negative pressure stripping process, and G is recycled in raw material A in a specific ratio; The method realizes the efficient utilization of by-product light oil in the asphalt preparation process, improves the asphalt yield, and can prepare high-quality mesophase asphalt and isotropic asphalt of different grades according to demand.

2. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The raw material A in S1 is a mixture of heavy aromatic oil and light oil G which is a by-product of the isotropic asphalt modulation process. The main properties of the heavy aromatic oil are: C / H value of 9-10, colloid content of 10%-30%, asphaltene content ≤1%, and fraction above 400°C ≥60%.

3. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The pressurized copolymerization conditions described in S1 are as follows: an initial nitrogen pressure of 0.1-0.5 MPa, a pressure of ≤2 MPa, a material temperature of 380-400°C, and a constant temperature time of 5-10 h during the constant temperature stage, and the ratio of the fraction B > 400°C to the fraction C < 400°C described in S1 is mC:mB=1 / 4~2 / 3, wherein mB is the mass of the fraction C > 400°C, and mC is the mass of the fraction C < 400°C.

4. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The thermal polycondensation conditions in S2 are nitrogen atmosphere protection and 380° C. to 420° C.

5. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The mesophase asphalt D described in S2 can be prepared into different grades as required, which is mainly achieved by the different constant temperature times in claim 7.

6. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The by-product light oil E and the <400℃ fraction C described in S3 are mixed in a specific ratio as a raw material for isotropic asphalt modulation, and the specific ratio is mE / mC=3 / 4~1, where mE is the mass of the by-product light oil E, and mC is the mass of the <400℃ fraction C.

7. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The air oxidation process in S3 is as follows: the material temperature is 310-330°C, the oxygen amount is 0.05-0.1m 3 / (h·kg); negative pressure gas stripping process: material temperature 360-380℃, vacuum degree 10~15Kpa, nitrogen volume 0.005~0.01m 3 / (h·kg).

8. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The isotropic asphalt F described in S3 can be prepared into different grades according to demand, which is mainly achieved by the different constant temperature times in claim 9.

9. The method for co-producing mesophase asphalt and isotropic asphalt according to claim 1, characterized in that: The by-product light oil G in S3 is recycled into the raw material A at a specific ratio, and the specific ratio is mG / mA=1 / 10~1 / 5, where mG is the mass of the by-product light oil G and mA is the total mass of the raw material A.

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