CN118185653A - Method for preparing mesophase pitch by seed crystal induced catalytic polycondensation - Google Patents
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- 238000006068 polycondensation reaction Methods 0.000 title claims abstract description 60
- 239000011302 mesophase pitch Substances 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims abstract description 37
- 230000003197 catalytic effect Effects 0.000 title claims abstract description 28
- 239000013078 crystal Substances 0.000 title claims abstract description 16
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims abstract description 87
- 239000010426 asphalt Substances 0.000 claims abstract description 38
- 238000006243 chemical reaction Methods 0.000 claims abstract description 32
- 238000010438 heat treatment Methods 0.000 claims abstract description 30
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000002994 raw material Substances 0.000 claims abstract description 18
- 238000004132 cross linking Methods 0.000 claims abstract description 17
- 238000003756 stirring Methods 0.000 claims abstract description 13
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 238000001914 filtration Methods 0.000 claims abstract description 10
- 239000012298 atmosphere Substances 0.000 claims abstract description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000009835 boiling Methods 0.000 claims abstract description 5
- 238000001816 cooling Methods 0.000 claims abstract description 4
- 238000001035 drying Methods 0.000 claims abstract description 4
- 238000012643 polycondensation polymerization Methods 0.000 claims abstract description 3
- 238000005406 washing Methods 0.000 claims abstract description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- 239000002002 slurry Substances 0.000 claims description 11
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 238000004523 catalytic cracking Methods 0.000 claims description 6
- 238000000605 extraction Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910052786 argon Inorganic materials 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 4
- 239000005977 Ethylene Substances 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 4
- 238000006477 desulfuration reaction Methods 0.000 claims description 3
- 230000023556 desulfurization Effects 0.000 claims description 3
- 239000000706 filtrate Substances 0.000 claims description 3
- 230000006698 induction Effects 0.000 claims description 3
- 239000011269 tar Substances 0.000 claims description 3
- 238000004517 catalytic hydrocracking Methods 0.000 claims description 2
- 239000011280 coal tar Substances 0.000 claims 1
- 238000002360 preparation method Methods 0.000 abstract description 12
- 229920000049 Carbon (fiber) Polymers 0.000 abstract description 6
- 239000004917 carbon fiber Substances 0.000 abstract description 6
- 239000003054 catalyst Substances 0.000 abstract description 6
- 239000002243 precursor Substances 0.000 abstract description 5
- 239000011295 pitch Substances 0.000 abstract description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 2
- 238000003763 carbonization Methods 0.000 description 6
- 239000011294 coal tar pitch Substances 0.000 description 6
- 239000012299 nitrogen atmosphere Substances 0.000 description 6
- 239000003575 carbonaceous material Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000000227 grinding Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 239000011301 petroleum pitch Substances 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- SMWDFEZZVXVKRB-UHFFFAOYSA-N Quinoline Chemical compound N1=CC=CC2=CC=CC=C21 SMWDFEZZVXVKRB-UHFFFAOYSA-N 0.000 description 2
- HUMNYLRZRPPJDN-UHFFFAOYSA-N benzaldehyde Chemical compound O=CC1=CC=CC=C1 HUMNYLRZRPPJDN-UHFFFAOYSA-N 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
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- 239000004005 microsphere Substances 0.000 description 2
- 238000002715 modification method Methods 0.000 description 2
- 239000011331 needle coke Substances 0.000 description 2
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 239000011949 solid catalyst Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000002841 Lewis acid Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 230000002152 alkylating effect Effects 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011300 coal pitch Substances 0.000 description 1
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- 239000012535 impurity Substances 0.000 description 1
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- 238000004519 manufacturing process Methods 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
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- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 125000005489 p-toluenesulfonic acid group Chemical group 0.000 description 1
- QNGNSVIICDLXHT-UHFFFAOYSA-N para-ethylbenzaldehyde Natural products CCC1=CC=C(C=O)C=C1 QNGNSVIICDLXHT-UHFFFAOYSA-N 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
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- 239000000126 substance Substances 0.000 description 1
- 239000003930 superacid Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 239000011271 tar pitch Substances 0.000 description 1
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- Working-Up Tar And Pitch (AREA)
Abstract
The invention discloses a method for preparing mesophase pitch by seed crystal induced catalytic polycondensation, which comprises the following steps: performing thermal condensation polymerization on fractions with boiling points of 350-520 ℃ in the refined asphalt raw material in an inert atmosphere to obtain polycondensated asphalt; crushing the polycondensation asphalt, extracting toluene, and separating toluene insoluble matters; crushing toluene insoluble matters, mixing with concentrated sulfuric acid, heating and stirring, cooling, filtering, washing with water and drying to obtain a sulfonated intermediate phase; uniformly mixing a refined asphalt raw material, p-toluenesulfonic acid and a sulfonated mesophase in proportion, performing a crosslinking reaction under an inert atmosphere, and then performing an induced catalytic polycondensation reaction to obtain a polycondensation mesophase; and devolatilizing the polycondensation mesophase under negative pressure to obtain spinnable mesophase pitch. The invention adopts low price of raw materials, has simple preparation process, does not need to remove catalyst, and the prepared mesophase pitch has good spinnability and can be used as a high-quality precursor of high-performance pitch-based carbon fiber.
Description
Technical Field
The invention relates to the technical field of preparation of high-performance carbon material precursors, in particular to a method for preparing mesophase pitch by seed crystal induced catalytic polycondensation.
Background
Mesophase pitch (mesophase pitch, MP for short) is a mixture of multiple kinds of flat disc-shaped polycyclic aromatic hydrocarbons with relative molecular mass of 370-2000, also called liquid crystal phase pitch. Mesophase pitch is a good quality precursor for preparing high-end carbon materials, and is in demand in the market. The mesophase pitch can be used for preparing high-performance pitch-based carbon fibers, mesophase carbon microspheres, composite materials, needle coke, mesophase pitch-based foam carbon, mesophase pitch-based electrode materials, adhesives, high-temperature lubricants and the like, and the carbon materials play a vital role in the fields of aerospace, military industry, energy storage, civil materials and the like, so that the research work of the mesophase pitch has important significance. The mesophase pitch with good spinnability can be subjected to steps of spinning, pre-oxidation, carbonization, graphitization, surface treatment and the like to obtain the mesophase pitch-based carbon fiber. The mesophase pitch-based carbon fiber has excellent performance, is applied to the fields of aerospace, national defense, military industry, mechanical manufacturing and the like, and takes up an increasingly important position in new materials.
The raw materials for preparing the mesophase pitch at present are mainly coal pitch, petroleum pitch, catalytic cracking slurry oil (FCC slurry oil), ethylene tar, refined naphthalene, hydrogenated tail oil, aromatic substances and some blends. Among them, FCC slurry oil belongs to the refining residual products, is generally recycled or used as ship fuel, and has low economic utilization value. The naphthenic FCC slurry oil is rich in 2-5 ring polycyclic aromatic hydrocarbon, has high aromatic hydrocarbon content of about 60-90 wt%, and is excellent material for preparing mesophase pitch, needle coke and other carbon material. However, both the light component and the heavy component contained in the slurry oil are unfavorable for the formation of the mesophase, and the middle-stage fraction of the slurry oil needs to be cut as a raw material of the mesophase pitch.
The preparation method of the mesophase pitch comprises a direct thermal polycondensation method, a solvent extraction method, a catalytic modification method, a hydrogenation modification method, a co-carbonization method, a pressurizing-vacuum two-step thermal polycondensation method, a catalytic polycondensation method and the like. The simple thermal shrinkage polymerization generates mesophase pitch with wide molecular weight distribution range and poor spinning performance, and two or more raw materials are needed for co-carbonization, so that the difficulty in controlling the quality of the product is high; the Lewis acid or solid super acid catalyst used for catalyzing polycondensation is not easy to be removed from the product, and equipment is corroded. Because of the difference of raw materials and the difference of preparation methods, the prepared mesophase pitch has quite different properties.
For example, chinese patent CN104610994a provides a method for preparing mesophase pitch with low softening point and high mesophase content, which comprises: under inert atmosphere or nitrogen atmosphere, performing primary co-carbonization treatment on the fraction of naphthenic base atmospheric residuum at 480-560 ℃ and catalytic cracking slurry oil of naphthenic base vacuum distillate oil to obtain primary co-carbonized asphalt; and (3) under inert atmosphere or nitrogen atmosphere, carrying out secondary co-carbonization treatment on the primary co-carbonized asphalt and the catalytic cracking slurry oil of the cycloalkyl vacuum distillate oil to obtain the mesophase asphalt. The optical structure of the mesophase pitch prepared by the secondary co-carbon method is a large-area streamline body, the softening point is low, and the spinnability is good. But adopts two raw materials, and the two times of the co-carbonization process are carried out, the process is complex, and the intermediate phase content of partial intermediate phase content products is low.
For example, chinese patent CN106929084a discloses a method for preparing spinnable mesophase pitch from petroleum pitch, which uses petroleum pitch containing almost no toluene insoluble matter and quinoline insoluble matter as raw material, and carries out hydrotreating in the presence of hydrogen-supplying solvent after heat treatment and reduced pressure distillation, and finally carries out heat treatment again to obtain spinnable mesophase pitch. The mesophase pitch prepared by the method provided by the invention has relatively low softening point and high mesophase content, and is suitable for preparing high-performance carbon fibers. However, the mesophase content of the mesophase pitch prepared by the method can only be increased to more than 90%, and the addition of the hydrogen-supplying solvent increases the cost.
In another example, chinese patent CN102181299a discloses alkylating asphalt with an olefin and a catalyst, and then performing a thermal polycondensation reaction to obtain a mesophase asphalt with a low softening point and a high mesophase content. However, the method adopts a solid catalyst, and has the defects of high cost and high risk in industrialization of the mesophase pitch because the catalyst has strong corrosiveness, has high requirements on reaction equipment and is difficult to remove.
As further disclosed in chinese patent CN113174274a, a method for preparing modified mesophase pitch from coal liquefaction residue is disclosed, wherein the extract of coal liquefaction residue powder is evaporated and carbonized to obtain mesophase pitch; mixing mesophase pitch with a cross-linking agent and a catalyst, and then carrying out a cross-linking reaction to obtain an oligomer; and carrying out high-temperature heat treatment on the oligomer to obtain the modified mesophase pitch. The cross-linking agent used in the cross-linking reaction is benzaldehyde, the catalyst is p-toluenesulfonic acid, and the intermediate phase asphalt is modified through the cross-linking reaction, but the patent firstly generates intermediate phase asphalt, and the intermediate phase asphalt is modified through cross-linking and heat treatment, so that more treatment steps are designed.
In summary, the existing methods for preparing mesophase pitch are more, and the methods such as direct thermal polycondensation, catalytic polycondensation and the like have the problems that the mesophase pitch with good spinnability is difficult to generate or the solid impurities are difficult to remove. In addition, in order to increase the mesophase content of the product, the overall heat treatment time is generally longer, and the situation of excessive polycondensation and local coking is easy to occur in industrial production.
Disclosure of Invention
The invention provides a method for preparing mesophase pitch by seed crystal induced catalytic polycondensation, which aims to solve the problems of long heat treatment time, multiple technological processes, difficult removal of a solid catalyst, poor spinning performance of the mesophase pitch and the like in the preparation method of the mesophase pitch in the prior art. The method has simple process and obviously shortened heat treatment time, can produce the mesophase pitch with good spinnability, and can be used as a high-quality precursor of high-end carbon materials.
The invention is realized by adopting the following technical scheme.
A method for preparing mesophase pitch by seed crystal induced catalytic polycondensation comprises the following steps:
S1, performing thermal condensation polymerization on fractions with boiling points of 350-520 ℃ in a refined asphalt raw material at a reaction temperature of 420-440 ℃ in an inert atmosphere for 4-6 hours to obtain polycondensed asphalt;
S2, crushing the polycondensed asphalt obtained in the step S1, and then extracting toluene to separate toluene soluble matters and toluene insoluble matters;
S3, crushing the toluene insoluble matters obtained in the step S2, mixing the crushed toluene insoluble matters with concentrated sulfuric acid, wherein the dosage of the concentrated sulfuric acid is 2-20 times of the quantity of the toluene insoluble matters, heating and stirring the mixture at 120-160 ℃ for 30-60 min, cooling, filtering and washing the mixture until the pH value of the filtrate is 7.0, and drying the solid obtained by filtering to obtain a sulfonated intermediate phase;
S4, uniformly mixing the refined asphalt raw material, the p-toluenesulfonic acid and the sulfonated mesophase obtained in the step S3 according to the mass ratio of 100 (1-5) (0.1-10), heating to 110 ℃ at the speed of 2-5 ℃/min under inert atmosphere, performing crosslinking reaction for 0.5-2 h within the temperature range of 110+/-5 ℃, and then performing induced catalytic polycondensation reaction at 420-440 ℃ for 4-6 h to obtain a polycondensation mesophase;
S5, devolatilizing the polycondensation mesophase obtained in the step S4 under negative pressure to obtain spinnable mesophase pitch.
Further, in the steps S1 and S4, the refined asphalt raw material is obtained by pretreating one or more of coal tar pitch, catalytic cracking slurry oil, hydrocracking tail oil and ethylene tar pitch; the pretreatment is one or more of heat treatment, extraction, desulfurization and solid removal.
Further, in step S2, the toluene-soluble matters are used as the refined asphalt raw material in step S1 or step S4.
In step S2, the temperature of toluene extraction is 20-40 ℃ above the boiling point of toluene, and the time of toluene extraction is 0.5-3 h.
Further, in step S3, toluene insoluble matters are pulverized to 40 mesh or more.
Further, in the step S3, the solid obtained by filtration is dried at 100 to 150 ℃ for 10 to 60 minutes.
Further, in step S4, the refined asphalt raw material, p-toluenesulfonic acid and the sulfonated mesophase are uniformly mixed by grinding, stirring or sieving.
Further, in step S4, after the crosslinking reaction is finished, the temperature is continuously raised at a rate of 2-5 ℃/min, the reaction is carried out under a closed condition until the pressure is 1-6 MPa, and the reaction pressure is maintained to be 1-6 MPa during the reaction time.
Further, in step S4, in the induction catalytic polycondensation reaction, the stirring rate is 300 to 600rpm.
In the step S1, the inert gas is nitrogen or argon; in step S4, the inert gas is nitrogen or argon.
In step S5, the devolatilization temperature under negative pressure is 350-380 ℃ and the time is 0.5-3 h.
The application has the following beneficial effects.
The polycondensation reaction process is simpler, the process of the polycondensation reaction is accelerated due to the catalysis of the p-toluenesulfonic acid and the induction of the sulfonated mesophase, the reaction time is short, the softening point of the prepared spinnable mesophase pitch is low (270-300 ℃), the content of the mesophase is high (98-100%), the spinnability is good, and the spinnability is good, so that the spinnability is good, and the spinnability can be used for preparing high-performance pitch-based carbon fibers and can be used as precursors of high-quality carbon microspheres.
Detailed Description
The present application is further illustrated below with reference to examples.
The experimental methods used in the following preparation examples and examples are conventional methods unless otherwise specified; materials, reagents and the like used in the following preparation examples and examples are commercially available unless otherwise specified.
Preparation example
1) Carrying out heat treatment, desulfurization and de-solidification on the catalytic cracking slurry oil to obtain refined asphalt, distilling to obtain a fraction at 350-520 ℃, and carrying out thermal polycondensation reaction at 420 ℃ in a nitrogen atmosphere for 6 hours to obtain polycondensed asphalt;
2) Crushing the polycondensation asphalt, extracting toluene at 135 ℃ for 1h, and separating toluene soluble matters and toluene insoluble matters;
3) Pulverizing toluene insoluble matters to 60 meshes, mixing with concentrated sulfuric acid with 10 times of toluene insoluble matters, heating and stirring at 120 ℃ for 40min, cooling and filtering, filtering with clear water until the pH of the filtrate is 7.0, and drying the solid obtained by filtering at 100 ℃ for 20min to obtain a sulfonated intermediate phase.
Example 1
Uniformly mixing refined asphalt obtained from coal tar pitch, p-toluenesulfonic acid and sulfonated mesophase obtained from preparation example in a grinding mode according to the mass ratio of 100:1:4, introducing nitrogen to replace air in a reactor, sealing the reactor, heating at a speed of 5 ℃/min, heating to 110 ℃, and carrying out crosslinking reaction for 1h at 110 ℃; after the crosslinking reaction is finished, the induced catalytic polycondensation reaction is carried out: continuously heating at a speed of 2 ℃/min, reacting under a closed condition until the pressure in the reactor is 1MPa, then opening a gas outlet of the reactor and maintaining the pressure in the reactor to be 1MPa, and reacting for 6 hours under the conditions that the reaction temperature is 420 ℃ and the stirring speed is 300rpm to obtain a polycondensation intermediate phase;
And devolatilizing the polycondensation mesophase under negative pressure, wherein the treatment temperature is 360 ℃ and the treatment time is 1h, so as to obtain the spinnable mesophase pitch, the content of the mesophase is 99%, and the softening point is 289 ℃.
Example 2
Uniformly mixing refined asphalt obtained from coal tar pitch, p-toluenesulfonic acid and sulfonated mesophase obtained from preparation example in a sieving way according to the mass ratio of 100:2:7, introducing argon to replace air in a reactor, sealing the reactor, heating at the speed of 2 ℃/min, heating to 105 ℃, and carrying out crosslinking reaction for 2 hours at 105 ℃; after the crosslinking reaction is finished, the induced catalytic polycondensation reaction is carried out: continuously heating at a speed of 3 ℃/min, reacting under a closed condition until the pressure in the reactor is 4MPa, then opening a gas outlet of the reactor and maintaining the pressure in the reactor to be 4MPa, and reacting for 5 hours under the conditions that the reaction temperature is 430 ℃ and the stirring speed is 400rpm to obtain a polycondensation mesophase;
And devolatilizing the polycondensation mesophase under negative pressure, wherein the treatment temperature is 370 ℃ and the treatment time is 1h, so that the spinnable mesophase pitch is obtained, the content of the mesophase is 98%, and the softening point is 291 ℃.
Example 3
Uniformly mixing refined asphalt obtained from coal tar pitch, p-toluenesulfonic acid and sulfonated intermediate phase obtained from preparation example in a grinding mode according to the mass ratio of 100:4:2, introducing nitrogen to replace air in a reactor, sealing the reactor, heating at the speed of 4 ℃/min, heating to 112 ℃, and carrying out crosslinking reaction at 112 ℃ for 0.8h; after the crosslinking reaction is finished, the induced catalytic polycondensation reaction is carried out: continuously heating at a speed of 4 ℃/min, reacting under a closed condition until the pressure in the reactor is 6MPa, then opening a gas outlet of the reactor and maintaining the pressure in the reactor to be 6MPa, and reacting for 4 hours under the conditions that the reaction temperature is 420 ℃ and the stirring speed is 500rpm to obtain a polycondensation intermediate phase;
and devolatilizing the polycondensation mesophase under negative pressure, wherein the treatment temperature is 380 ℃ and the treatment time is 0.5h, so as to obtain the spinnable mesophase pitch, the content of the mesophase is 99%, and the softening point is 285 ℃.
Example 4
Uniformly mixing refined asphalt obtained from coal tar pitch, p-toluenesulfonic acid and sulfonated mesophase obtained from preparation example in a grinding mode according to the mass ratio of 100:3:5, introducing nitrogen to replace air in a reactor, sealing the reactor, heating at a speed of 3 ℃/min, heating to 110 ℃, and carrying out crosslinking reaction for 2 hours at 110 ℃; after the crosslinking reaction is finished, the induced catalytic polycondensation reaction is carried out: continuously heating at a speed of 5 ℃/min, reacting under a closed condition until the pressure in the reactor is 6MPa, then opening a gas outlet of the reactor and maintaining the pressure in the reactor to be 6MPa, and reacting for 4 hours at a reaction temperature of 440 ℃ and a stirring speed of 600rpm to obtain a polycondensation intermediate phase;
and devolatilizing the polycondensation mesophase under negative pressure, wherein the treatment temperature is 360 ℃ and the treatment time is 1h, so that the spinnable mesophase pitch is obtained, the content of the mesophase is 99%, and the softening point is 290 ℃.
Comparative example 1
Heating refined asphalt obtained from coal tar pitch at a speed of 3 ℃/min under nitrogen atmosphere, performing polycondensation reaction at a reaction temperature of 420 ℃ for 2 hours, controlling the reaction pressure to be 6MPa, and stirring at a speed of 300rpm to obtain an intermediate; performing secondary polycondensation reaction on the intermediate in nitrogen atmosphere, wherein the reaction temperature is 425 ℃, and the reaction time is 2 hours, so as to obtain a polycondensation intermediate phase; and devolatilizing the polycondensation intermediate phase under negative pressure, wherein the treatment temperature is 370 ℃ and the treatment time is 2 hours, so that the spinnable asphalt is obtained, the intermediate phase content is 73%, and the softening point is 247 ℃.
Comparative example 2
Heating refined asphalt obtained by removing ethylene tar in nitrogen at a speed of 4 ℃/min, performing polycondensation reaction at 435 ℃ for 2 hours, controlling the reaction pressure to 2MPa, and stirring at 400rpm to obtain an intermediate; performing secondary polycondensation reaction on the intermediate in nitrogen atmosphere, wherein the reaction temperature is 440 ℃, and the reaction time is 2 hours, so as to obtain a polycondensation intermediate phase; and devolatilizing the polycondensation intermediate phase under negative pressure, wherein the treatment temperature is 380 ℃ and the treatment time is 1h, so that the spinnable asphalt is obtained, the content of the intermediate phase is 88%, and the softening point is 279 ℃.
The embodiments of the present invention are all preferred embodiments of the present invention, and are not intended to limit the scope of the present invention in this way, therefore: all equivalent changes in structure, shape and principle of the invention should be covered in the scope of protection of the invention.
Claims (10)
1. A method for preparing mesophase pitch by seed crystal induced catalytic polycondensation is characterized in that: comprising the following steps:
S1, performing thermal condensation polymerization on fractions with boiling points of 350-520 ℃ in a refined asphalt raw material at a reaction temperature of 420-440 ℃ in an inert atmosphere for 4-6 hours to obtain polycondensed asphalt;
S2, crushing the polycondensed asphalt obtained in the step S1, and then extracting toluene to separate toluene soluble matters and toluene insoluble matters;
S3, crushing the toluene insoluble matters obtained in the step S2, mixing the crushed toluene insoluble matters with concentrated sulfuric acid, wherein the dosage of the concentrated sulfuric acid is 2-20 times of the quantity of the toluene insoluble matters, heating and stirring the mixture at 120-160 ℃ for 30-60 min, cooling, filtering and washing the mixture until the pH value of the filtrate is 7.0, and drying the solid obtained by filtering to obtain a sulfonated intermediate phase;
S4, uniformly mixing the refined asphalt raw material, the p-toluenesulfonic acid and the sulfonated mesophase obtained in the step S3 according to the mass ratio of 100 (1-5) (0.1-10), heating to 110 ℃ at the speed of 2-5 ℃/min under inert atmosphere, performing crosslinking reaction for 0.5-2 h within the temperature range of 110+/-5 ℃, and then performing induced catalytic polycondensation reaction at 420-440 ℃ for 4-6 h to obtain a polycondensation mesophase;
S5, devolatilizing the polycondensation mesophase obtained in the step S4 under negative pressure to obtain spinnable mesophase pitch.
2. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the steps S1 and S4, the refined asphalt raw material is obtained by pretreating one or more of coal tar asphalt, catalytic cracking slurry oil, hydrocracking tail oil and ethylene tar asphalt; the pretreatment is one or more of heat treatment, extraction, desulfurization and solid removal.
3. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in step S2, the toluene-soluble matter is used as the refined asphalt raw material in step S1 or step S4.
4. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the step S2, the temperature of toluene extraction is 20-40 ℃ above the boiling point of toluene, and the time of toluene extraction is 0.5-3 h.
5. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in step S3, toluene insoluble matters are crushed to 40 mesh or more.
6. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the step S3, the solid obtained by filtration is dried for 10 to 60 minutes at the temperature of 100 to 150 ℃.
7. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the step S4, after the crosslinking reaction is finished, the temperature is continuously increased at the speed of 2-5 ℃/min, the reaction is carried out under the airtight condition until the pressure is 1-6 MPa, and the reaction pressure is maintained to be 1-6 MPa in the reaction time.
8. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the step S4, in the induction catalytic polycondensation reaction, the stirring speed is 300-600 rpm.
9. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the step S1, the inert gas is nitrogen or argon; in step S4, the inert gas is nitrogen or argon.
10. The method for preparing mesophase pitch by crystal induced catalytic polycondensation according to claim 1, wherein: in the step S5, the devolatilization temperature under the negative pressure is 350-380 ℃ and the time is 0.5-3 h.
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