Process for refining aromatic hydrocarbon oligomers, refined aromatic hydrocarbon oligomers and use thereof

Abstract

The present application relates to the technical field of aromatic hydrocarbon polymer, in particular to a refining method of aromatic hydrocarbon oligomer, a refined aromatic hydrocarbon oligomer obtained by the refining method and application of the refined aromatic hydrocarbon oligomer. The refining method comprises: (1) first extraction of aromatic hydrocarbon oligomer containing catalyst and first solvent, first distillation of the obtained first extraction liquid to obtain crude aromatic hydrocarbon oligomer; (2) second extraction of the crude aromatic hydrocarbon oligomer and second solvent, second distillation of the obtained second extraction liquid to obtain refined aromatic hydrocarbon oligomer; wherein the first solvent is selected from oxygen-containing organic matter capable of forming a complex with the catalyst in the aromatic hydrocarbon oligomer. The refining method effectively removes catalyst and ash in the aromatic hydrocarbon oligomer; at the same time, the method simplifies the process flow and facilitates industrial production.

Description

Technical Field

[0001] This invention relates to the field of aromatic polymer technology, specifically to a method for refining aromatic oligomers, a refined aromatic oligomer obtained by the method, and its applications. Background Technology

[0002] Compared to HF / BF3 catalysts, which are toxic and highly corrosive gases, limiting the further development of oligomer preparation processes using HF / BF3 catalysts, solid Lewis acids have attracted widespread attention due to their excellent catalytic polymerization performance and high safety profile.

[0003] CN201210432308.4 discloses a method for preparing high-purity mesophase pitch. This method involves washing the pitch 2-10 times with 0.2% (v / v) dilute hydrochloric acid to remove the catalyst (i.e., AlCl3), yielding naphthalene pitch. However, because the AlCl3 coated with aromatic oligomers is difficult to contact the acid solution, the residual AlCl3 content in the naphthalene pitch is relatively high. CN201910901067.5 discloses a method for preparing spinning-grade synthetic mesophase pitch. This method uses ZrCl4 as a catalyst to react with refined naphthalene. The resulting product is then mixed with 5 times its volume of solvent pyridine. The liquid and solid components of the product are then separated using medium-speed qualitative filter paper. The pyridine solvent in the liquid component is removed by distillation, yielding an aromatic oligomer without the catalyst. However, because the solvent pyridine forms a complex with AlCl3, trace amounts of AlCl3 still remain in the solution formed by pyridine and the oligomer. CN201410402059.3 discloses a method for removing AlCl3 from aromatic oligomers. This method uses aromatic compounds such as naphthalene and methylnaphthalene as raw materials, and prepares oligomers through AlCl3-catalyzed polymerization. The oligomers are dissolved in toluene, then acid-washed with hydrochloric acid solution, allowed to stand and separate, and the lower layer containing the catalyst is removed. Next, sodium hydroxide solution is added for alkaline washing, and the mixture is allowed to stand and separate again, removing the lower alkaline layer. Then, deionized water is added for washing, and toluene is removed by vacuum distillation to obtain a high-quality mesophase pitch precursor with an ash content of 150 ppm and a minimum Al content of 2.8 ppm. However, due to the limited solubility of toluene in aromatic oligomers, significant losses occur after filtration, resulting in a low yield.

[0004] In summary, although there has been considerable academic research on aromatic oligomers in China, the resulting products still fall short of the requirements for high-performance carbon materials due to issues such as incomplete catalyst removal, high ash content, and numerous washing cycles. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical problems and provide a method for refining aromatic oligomers, a refined aromatic oligomer obtained by the method and its application. The method can effectively remove catalyst and ash from the aromatic oligomer, thereby effectively improving the purity of the refined aromatic oligomer. At the same time, the refined aromatic oligomer obtained by the method meets the needs of high-performance carbon materials.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for purifying aromatic oligomers, the method comprising the following steps:

[0007] (1) The aromatic oligomer containing the catalyst and the first solvent are subjected to a first extraction, and the first extract is subjected to a first distillation to obtain crude aromatic oligomer.

[0008] (2) The crude aromatic oligomer and the second solvent are subjected to a second extraction, and the resulting second extract is subjected to a second distillation to obtain refined aromatic oligomer;

[0009] The first solvent is selected from oxygen-containing organic compounds that can form complexes with the catalyst in the aromatic oligomer.

[0010] Preferably, the first solvent is selected from at least one of furan, furfural, and tetrahydrofuran.

[0011] Preferably, the second solvent is selected from aromatic compounds, and more preferably from at least one of benzene, toluene, and xylene.

[0012] The second aspect of the present invention provides a refined aromatic oligomer obtained by the refining method provided in the first aspect.

[0013] The third aspect of this invention provides an application of the refined aromatic oligomers provided in the second aspect in carbon materials.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) The purification method provided by the present invention effectively removes catalyst and ash from aromatic oligomers by using two extraction and two distillation techniques, combined with a specific first solvent; especially before the second distillation, the second extract is subjected to acid washing, alkali washing and water washing in sequence, which reduces the number of washing times and further effectively removes catalyst and ash from aromatic oligomers, so that the catalyst content in the purified aromatic oligomers is ≤200mg / kg and the ash content is ≤200mg / kg, that is, the purity of the purified aromatic oligomers is effectively improved; at the same time, the purification method effectively improves the yield of purified aromatic oligomers while ensuring that the purified aromatic oligomers have high purity;

[0016] (2) The refining method provided by the present invention simplifies the process flow, is easy to operate, and is convenient for industrial production;

[0017] (3) The refined aromatic oligomers provided by the present invention can be used in carbon materials to effectively improve the performance of carbon materials. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] In this invention, unless otherwise specified, the terms "first" and "second" do not indicate a sequence or limit the specific materials or steps; they are merely used to distinguish between different materials or steps. For example, "first" and "second" in "first solvent" and "second solvent" simply indicate that they are not the same solvent; similarly, "first" and "second" in "first extraction" and "second extraction" simply indicate that they are not the same extraction.

[0020] The first aspect of this invention provides a method for purifying aromatic oligomers, the method comprising the following steps:

[0021] (1) The aromatic oligomer containing the catalyst and the first solvent are subjected to a first extraction, and the first extract is subjected to a first distillation to obtain crude aromatic oligomer.

[0022] (2) The crude aromatic oligomer and the second solvent are subjected to a second extraction, and the resulting second extract is subjected to a second distillation to obtain refined aromatic oligomer;

[0023] The first solvent is selected from oxygen-containing organic compounds that can form complexes with the catalyst in the aromatic oligomer.

[0024] The inventors of this invention have discovered that existing technologies, such as using aromatic compounds like toluene and pyridine, and washing techniques (acid washing, alkali washing, and water washing), cannot effectively remove solid catalysts from aromatic oligomers. To address this, the inventors have improved the solvents by employing specific first and second solvents, along with techniques involving two extractions and two distillations. This effectively reduces the catalyst and ash content in aromatic oligomers. Furthermore, by combining this with a specific washing method, the number of washing cycles is reduced while further removing catalysts and ash from the aromatic oligomers, thereby improving the purity and yield of the refined aromatic oligomers.

[0025] In this invention, unless otherwise specified, the aromatic oligomers generally refer to aromatic polymers with a degree of polymerization of 2-10.

[0026] In this invention, the aromatic oligomer, in addition to having a specific amount of catalyst, also possesses high viscosity and high ash content. Preferably, the catalyst content of the aromatic oligomer is ≥2 wt%, more preferably 2-30 wt%; the viscosity is ≥100 mPa·s, more preferably 100-500 mPa·s; and the ash content is ≥2 wt%, more preferably 2-30 wt%.

[0027] In this invention, unless otherwise specified, the catalyst content parameter is expressed as the metal element content, which is determined by inductively coupled plasma optical emission spectrometry (ICP). The specific testing method includes: firstly, the sample is pyrolyzed in a high-temperature pyrolysis tube containing carbon powder, where oxygen-containing compounds are quantitatively converted into carbon monoxide; then, the carrier gas carries the pyrolysis products into a series of scrubbers to remove acid gas and water vapor; finally, the sample is detected by an infrared detector; a known mass of sample is heated, ignited, and burned to obtain carbon-containing residue; the residue is burned off in a muffle furnace to obtain ash; the ash is melted with flux and dissolved in a tartaric acid-hydrochloric acid mixed solution; the solution is diluted with water to a certain volume; and the resulting aqueous solution is measured by an inductively coupled plasma optical emission spectrometer.

[0028] In this invention, unless otherwise specified, the viscosity parameter is measured using the method of "Determination of Kinematic Viscosity of Petroleum Asphalt (SH / T 0654-1998)"; the ash content parameter is measured using the method of "Determination of Ash Content of Petroleum Products (GB / T 508-1985)".

[0029] In this invention, the preparation of the aromatic oligomers has a wide range of options, as long as the aromatic oligomers meet the above-mentioned limitations. Preferably, the aromatic oligomers are prepared by the following method: under the action of the catalyst, aromatic-rich raw materials are subjected to a polymerization reaction to obtain the aromatic oligomers.

[0030] In some embodiments of the present invention, preferably, the catalyst is a solid acid catalyst, preferably selected from at least one of AlCl3, CuCl2, ZnCl2, FeCl3 and ZrCl4.

[0031] In some embodiments of the present invention, preferably, the aromatic-rich feedstock is selected from high-aromatic oils and / or aromatic compounds. From the perspective of reducing product costs, the aromatic-rich feedstock is selected from high-aromatic oils.

[0032] In this invention, the high aromatic hydrocarbon oil is selected from catalytic slurry clarified oil, diesel (e.g., hydrorefined diesel, catalytic cracking diesel, etc.), catalytic cracking cycle oil, coal tar, anthracene oil, wash oil, etc. produced by oil refining or coal chemical industry; the aromatic hydrocarbon compound is selected from at least one of naphthalene, anthracene, phenanthrene, pyrene, methylnaphthalene and perylene, preferably selected from refined naphthalene and / or refined anthracene.

[0033] In some embodiments of the present invention, preferably, the high-aromatic oil product satisfies the following conditions: aromatic content ≥ 50 wt%, preferably 50-99 wt%; solid content ≤ 20 mg / kg, preferably 1-10 mg / kg; total heteroatom content ≤ 3 wt%, preferably 0.1-1 wt%. Adopting these preferred conditions is more conducive to improving the quality of aromatic oligomers, thereby increasing the purity of refined aromatic oligomers. In the present invention, the solid content parameter includes, but is not limited to, catalysts, ash, and solid impurities; heteroatoms include, but are not limited to, S, N, and O atoms.

[0034] In this invention, unless otherwise specified, the aromatic hydrocarbon content parameter is determined by the method of "Determination of Hydrocarbons in Saturated Hydrocarbon Fractions of Gas Oil (Mass Spectrometry) (SH / T 0659-1998)"; the solid content parameter is determined by the method of "Determination of Ash Content in Petroleum Products (GB / T 508-1985)"; and the heteroatom content parameter is determined by the petrochemical industry standard "Determination of Carbon, Hydrogen and Nitrogen in Petroleum Products and Lubricants (Elemental Analyzer Method) (SH / T 0656-2017)".

[0035] In some embodiments of the present invention, preferably, the weight ratio of the catalyst to the aromatic-rich feedstock is 0.1-20:100, for example, 0.1:100, 1:100, 5:100, 8:100, 10:100, 15:100, 20:100, and any value within any range of two such values, preferably 5-10:100. By using these preferred conditions, the catalyst content in the low-aromatic polymer is effectively reduced while ensuring a high conversion rate of the aromatic-rich feedstock.

[0036] In some embodiments of the present invention, preferably, the conditions for the polymerization reaction include: a temperature of 40-300°C, more preferably 220-260°C; and a time of 0.5-12 h, more preferably 0.5-2 h. In the present invention, the polymerization rate increases with increasing reaction temperature, and the reaction time also becomes shorter.

[0037] In some embodiments of the present invention, preferably, in step (1), the weight ratio of the first solvent to the aromatic oligomer is 1-10:1, for example, 1:1, 2:1, 2.5:1, 3:1, 5:1, 5.5:1, 6:1, 8:1, 10:1, and any value within the range of any two values, preferably 2-6:1, more preferably 2.5-5.5:1. Using these preferred conditions is more conducive to removing the catalyst content from the aromatic oligomer.

[0038] In some embodiments of the present invention, preferably, the first solvent is selected from at least one of furan, furfural, and tetrahydrofuran. In the present invention, compared to toluene, the first solvent is selected from oxygen-containing organic compounds, such as furan, tetrahydrofuran, and furfural, which have higher solubility for aromatic oligomers and can form metal complexes with Lewis acid catalysts. Therefore, using an oxygen-containing organic compound as the first solvent can better dissociate the fused-ring aromatics attached to the solid catalyst, thereby effectively removing the catalyst from the aromatic oligomers.

[0039] In this invention, the first extraction aims to effectively remove the catalyst from the aromatic oligomers to obtain a first extract rich in aromatic oligomers. Preferably, the conditions for the first extraction include: a temperature of 15-35°C, more preferably 20-30°C; and a time of 0.1-10 h, more preferably 0.5-2 h.

[0040] In this invention, the first distillation aims to remove the first solvent from the first extract. Preferably, the operating pressure of the first distillation is atmospheric pressure, i.e., 100 kPa, and the operating temperature depends on the type of the first solvent. When the first solvent is furfural, the temperature of the first distillation is 165-180°C; when the first solvent is furan, the temperature of the first distillation is 35-50°C; and when the first solvent is tetrahydrofuran, the temperature of the first distillation is 75-85°C.

[0041] In this invention, the product of the first extraction is filtered before the first distillation to obtain the first extract. The filtration method is not limited in this invention, as long as the first extract and the first raffinate are separated.

[0042] In some embodiments of the present invention, preferably, in step (1), the viscosity of the crude aromatic oligomer is <100 mPa·s, preferably 50-99 mPa·s; the catalyst content is <2 wt%, preferably 0.1-1 wt%; the first solvent content is ≤5 wt%, preferably 0.1-3.5 wt%; and the ash content is <2 wt%, preferably 0.1-1.5 wt%.

[0043] In some embodiments of the present invention, preferably, in step (2), the weight ratio of the second solvent to the crude aromatic oligomer is 1-5:1, for example, 1:1, 1.5:1, 2:1, 3:1, 5:1, and any value within the range of any two values, preferably 1-2:1. Using these preferred conditions, by reducing the viscosity of the second extract, the ash and residual first solvent in the second extract are effectively removed.

[0044] In this invention, the second solvent is different from the first solvent, and the second solvent is less hydrophilic than the first solvent, making it easier for the second solvent to separate into layers with water. Preferably, the second solvent is selected from aromatic compounds, including but not limited to benzene, toluene, and xylene.

[0045] In some embodiments of the present invention, preferably, the conditions for the second extraction include: a temperature of 15-40°C, preferably 20-30°C; and a time of 0.1-10 h, preferably 0.5-2 h.

[0046] In this invention, the second distillation aims to remove the second solvent from the second extract. Preferably, the conditions for the second distillation include: a temperature of 110-150°C, more preferably 120-140°C; and a pressure of -90 to 100 kPa, more preferably -90 to 50 kPa. In this invention, unless otherwise specified, the pressure parameter refers to the equalization pressure.

[0047] In this invention, to further remove the catalyst content from the second extract, preferably, before the second distillation, the second extract is subjected to alkali washing, acid washing, and water washing in sequence.

[0048] In some embodiments of the present invention, preferably, the alkaline washing process includes: contacting the second extract and an alkaline solution and performing alkaline washing to obtain an alkaline washed product.

[0049] In one specific embodiment of the present invention, preferably, the weight ratio of the alkaline solution and the second extract is 0.5-2:1, for example, 0.5:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 2:1, and any value within any range of two values, preferably 0.8-1.5:1. In the present invention, the concentration of the alkaline solution is 1-10 wt%, and the alkali in the alkaline solution is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate.

[0050] In one specific embodiment of the present invention, preferably, the number of alkaline washings is 1-8 times, more preferably 1-3 times.

[0051] In some embodiments of the present invention, preferably, the pickling process includes: contacting the alkaline washing product with an acid solution and performing pickling to obtain the pickled product.

[0052] In one specific embodiment of the present invention, preferably, the weight ratio of the acid solution and the second extract is 0.5-2:1, for example, 0.5:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 2:1, and any value within any range of two such values, preferably 0.8-1.5:1. In the present invention, the concentration of the acid solution is 5-10 wt%; the acid in the acid solution is selected from at least one of hydrochloric acid, nitric acid, and sulfuric acid.

[0053] In one specific embodiment of the present invention, preferably, the pickling is performed 1-5 times, more preferably 1-2 times.

[0054] In some embodiments of the present invention, preferably, the water washing process includes: contacting the acid-washed product with water and washing it to obtain a water-washed product.

[0055] In one specific embodiment of the present invention, preferably, the weight ratio of the water and the second extract is 0.5-2:1, for example, 0.5:1, 0.8:1, 1:1, 1.5:1, 2:1, and any value within the range of any two values, preferably 0.8-1.5:1. In the present invention, the water includes, but is not limited to, deionized water.

[0056] In one specific embodiment of the present invention, preferably, the number of water washes is 1-5 times, more preferably 1-2 times.

[0057] The second aspect of the present invention provides a refined aromatic oligomer obtained by the refining method provided in the first aspect.

[0058] The method provided by this invention can effectively remove catalyst and ash content from aromatic oligomers, resulting in refined aromatic oligomers with high purity and high yield.

[0059] In some embodiments of the present invention, preferably, the refined aromatic oligomer contains a catalyst content ≤200 mg / kg; an ash content ≤200 mg / kg; a carbon content of 90.5-93 wt%; and a hydrogen content of 7-8 wt%.

[0060] In this invention, the carbon and hydrogen content is measured according to the petrochemical industry standard "Determination of carbon, hydrogen and nitrogen in petroleum products and lubricants by elemental analyzer method (SH / T 0656-2017)".

[0061] The third aspect of the present invention provides an application of the refined aromatic oligomers provided in the second aspect in carbon materials, preferably in mesophase pitch, coated pitch, impregnated pitch, conductive carbon black, and hydrogen fuel cell catalyst supports.

[0062] According to a particularly preferred embodiment of the present invention, a method for purifying aromatic oligomers includes the following steps:

[0063] (1) The aromatic oligomer containing the catalyst and the first solvent are subjected to a first extraction, and the first extract is subjected to a first distillation to obtain crude aromatic oligomer.

[0064] (2) The crude aromatic oligomer and the second solvent are subjected to a second extraction. The second extract is then washed with alkali, acid and water in sequence. The water-washed product is then distilled to obtain the refined aromatic oligomer.

[0065] The first solvent is selected from at least one of furan, furfural, and tetrahydrofuran; the weight ratio of the first solvent to the aromatic oligomer is 2.5-5.5:1.

[0066] The aromatic oligomer contains a catalyst content of 2-30 wt%, a viscosity of 100-500 mPa·s, and an ash content of 2-30 wt%.

[0067] The present invention will be described in detail below through embodiments.

[0068] The catalyst content parameter is expressed as the metal element content, which is determined by inductively coupled plasma optical emission spectrometry (ICP). The specific testing method includes: first, the sample is pyrolyzed in a high-temperature pyrolysis tube containing carbon powder, where oxygen-containing compounds are quantitatively converted into carbon monoxide; then, the carrier gas carries the pyrolysis products into a series of scrubbers to remove acid gas and water vapor; finally, the samples are detected by an infrared detector; a known mass of the sample is heated, ignited, and burned to obtain carbon-containing residues. The residues are burned off in a muffle furnace to obtain ash, which is then melted with flux and dissolved in a tartaric acid-hydrochloric acid mixed solution. The solution is diluted to a certain volume with water, and the resulting aqueous solution is measured by inductively coupled plasma optical emission spectrometry.

[0069] Viscosity parameters were measured using the method described in "Determination of Kinematic Viscosity of Petroleum Asphalt (SH / T 0654-1998)".

[0070] The ash content and solid content parameters were both determined according to the "Determination of Ash Content in Petroleum Products (GB / T 508-1985)".

[0071] The aromatic hydrocarbon content parameter was determined using the method specified in "Determination of Hydrocarbons in Saturated Hydrocarbon Fractions of Gas Oil (Mass Spectrometry) (SH / T 0659-1998)";

[0072] The heteroatom content parameters and carbon and hydrogen element content parameters were all measured using the petrochemical industry standard "Determination of carbon, hydrogen and nitrogen in petroleum products and lubricants (elemental analyzer method) (SH / T 0656-2017)".

[0073] The physical properties of the refined aromatic oligomers (S1-S12 and DS1-DS3) obtained in Examples 1-12 and Comparative Examples 1-3 are listed in Table 1.

[0074] Example 1

[0075] 1) 10g of catalyst (AlCl3) and 100g of naphthalene were polymerized at 260℃ for 0.5h to obtain an aromatic oligomer containing the catalyst; wherein, the catalyst content in the aromatic oligomer was 2.74wt%; the viscosity was 483mPa·s; and the ash content was 10wt%.

[0076] 2) The first solvent (THF) and the above-mentioned aromatic oligomers were subjected to a first extraction at a weight ratio of 5:1 (temperature 25℃, time 1h), filtered, and the first extract was subjected to a first distillation (pressure 100kPa, temperature 80℃) to obtain crude aromatic oligomers; wherein, the crude aromatic oligomers contained 0.28wt% catalyst, 3.2wt% first solvent, 1.1wt% ash, and 96mPa·s.

[0077] 3) The second solvent (toluene) and the above crude aromatic oligomer were subjected to a second extraction at a weight ratio of 10:9 (temperature 25°C, time 1 h), and filtered to obtain the second extract.

[0078] 4) The second extract was washed twice with 10wt% sodium hydroxide solution, once with 5wt% hydrochloric acid solution, and twice with deionized water to obtain the washed product; wherein the weight ratio of the sodium hydroxide solution, hydrochloric acid solution and deionized water to the second extract was 1:1.

[0079] 5) The above-mentioned water-washed product was subjected to a second distillation (temperature 130℃, pressure -90kPa) to obtain refined aromatic oligomer S1.

[0080] Example 2

[0081] 1) 5g of catalyst (CuCl2) and 100g of anthracene were polymerized at 220℃ for 2h to obtain an aromatic oligomer containing the catalyst; wherein, the catalyst content in the aromatic oligomer was 2.9wt%; the viscosity was 459mPa·s; and the ash content was 4.76wt%.

[0082] 2) The first solvent (furan) and the above-mentioned aromatic oligomers were subjected to a first extraction at a weight ratio of 3:1 (temperature 20℃, time 1h), filtered, and the first extract was subjected to a first distillation (pressure 100kPa, temperature 40℃) to obtain crude aromatic oligomers; wherein, the crude aromatic oligomers contained 0.67wt% catalyst, 1.4wt% first solvent, 1.12wt% ash, and 56mPa·s.

[0083] 3) The second solvent (benzene) and the above crude aromatic oligomer were subjected to a second extraction at a weight ratio of 2:1 (temperature 20°C, time 1h), and filtered to obtain the second extract.

[0084] 4) The second extract was washed three times with 5 wt% sodium hydroxide solution, twice with 8 wt% hydrochloric acid solution, and twice with deionized water to obtain the washed product; wherein the weight ratio of the sodium hydroxide solution, hydrochloric acid solution and deionized water to the second extract was 1.5:1.

[0085] 5) The above-mentioned water-washed product was subjected to a second distillation (temperature 130℃, pressure -90kPa) to obtain refined aromatic oligomer S2.

[0086] Example 3

[0087] 1) 10g of catalyst (FeCl3) and 100g of diesel oil (aromatic content 67.2wt%, solid content 8mg / kg, heteroatom content 1wt%) were polymerized at 240℃ for 1h to obtain an aromatic oligomer containing the catalyst; wherein, the catalyst content in the aromatic oligomer was 4.99wt%; the viscosity was 416mPa·s; and the ash content was 9.09wt%.

[0088] 2) The first solvent (furfural) and the above-mentioned aromatic oligomers were subjected to a first extraction at a weight ratio of 1:1 (temperature 30℃, time 0.5h), filtered, and the first extract was subjected to a first distillation (pressure 100kPa, temperature 170℃) to obtain crude aromatic oligomers; wherein, the crude aromatic oligomers contained 0.47wt% catalyst, 1.8wt% first solvent, 0.7wt% ash, and 58mPa·s.

[0089] 3) The second solvent (xylene) and the above crude aromatic oligomer were subjected to a second extraction at a weight ratio of 1:1 (temperature 30℃, time 0.5h), and filtered to obtain the second extract.

[0090] 4) The second extract was washed three times with 10wt% sodium hydroxide solution, twice with 10wt% hydrochloric acid solution, and twice with deionized water to obtain the washed product; wherein the weight ratio of the sodium hydroxide solution, hydrochloric acid solution and deionized water to the second extract was 0.8:1.

[0091] 5) The above-mentioned water-washed product was subjected to a second distillation (temperature 140℃, pressure -90kPa) to obtain refined aromatic oligomer S3.

[0092] Example 4

[0093] The method of Example 1 is followed, except that in step 1), the polymerization reaction conditions are replaced with a temperature of 200°C and a time of 5 hours to obtain an aromatic oligomer containing a catalyst; wherein the content of the catalyst in the aromatic oligomer is 2.74 wt%; the viscosity is 432 mPa·s; and the ash content is 10 wt%.

[0094] Under the same conditions, refined aromatic oligomer S4 was obtained.

[0095] Example 5

[0096] The method of Example 1 is followed, except that in step 2), the weight ratio of the first solvent (THF) and the above-mentioned aromatic oligomer is replaced with 20:9 to obtain crude aromatic oligomer; wherein, the crude aromatic oligomer contains 0.5 wt% catalyst, 1.5 wt% first solvent, 1.97 wt% ash, and 83 mPa·s.

[0097] Under the same conditions, refined aromatic oligomer S5 was obtained.

[0098] Example 6

[0099] The method of Example 1 is followed, except that in step 3), the weight ratio of the second solvent (benzene) and the above crude aromatic oligomer is replaced with 3:1 to obtain the second extract.

[0100] Under the same conditions, refined aromatic oligomer S6 was obtained.

[0101] Example 7

[0102] The method is the same as in Example 1, except that in step 3), the second solvent is replaced with pyrrole to obtain the second extract.

[0103] Under the same conditions, refined aromatic oligomer S7 was obtained.

[0104] Example 8

[0105] The method of Example 1 is followed, except that in step 4), the number of times of alkali washing and water washing is once, and the other conditions are the same, to obtain refined aromatic oligomer S8.

[0106] Example 9

[0107] The method of Example 1 is followed, except that in step 4), the second extract is subjected to acid washing, alkali washing and water washing in sequence, while the other conditions are the same, to obtain refined aromatic oligomer S9.

[0108] Example 10

[0109] The method of Example 1 is followed, except that the crude aromatic oligomer obtained in step 1) is subjected to step 4) (i.e., alkali washing, acid washing and water washing in sequence), and the water-washed product is then subjected to steps 3) and 5) to obtain refined aromatic oligomer S10.

[0110] Example 11

[0111] The method is the same as in Example 1, except that step 4) is omitted, that is, the second extract obtained in step 3) is directly subjected to a second distillation to obtain refined aromatic oligomer S11.

[0112] Example 12

[0113] The method of Example 1 is followed, except that in step 2), the weight ratio of the first solvent (THF) and the above-mentioned aromatic oligomer is replaced with 10:1 to obtain crude aromatic oligomer; wherein, the crude aromatic oligomer contains 0.32 wt% catalyst, 3.8 wt% first solvent, 1.26 wt% ash, and 93 mPa·s.

[0114] Under the same conditions, purified aromatic oligomer S12 was obtained.

[0115] Comparative Example 1

[0116] The method of Example 1 is followed, except that step 2) is omitted, that is, the aromatic oligomers obtained in step 1) are directly subjected to a second extraction, and the other conditions are the same to obtain refined aromatic oligomers DS1.

[0117] Comparative Example 2

[0118] Following the method of Example 1, except that in step 2), the first solvent was replaced with pyridine, while the other conditions remained the same, to obtain the purified aromatic oligomer DS2.

[0119] Comparative Example 3

[0120] Following the method of Example 1, except that in step 2), the first solvent was replaced with toluene, while the other conditions remained the same, to obtain the refined aromatic oligomer DS3.

[0121] Table 1

[0122]

[0123] Note: 1- Catalyst content is calculated based on metal element content; 2- Yield is (the ratio of the mass of refined aromatic oligomer to the mass of raw aromatic oligomer) × 100%.

[0124] As can be seen from the results in Table 1, compared with Comparative Examples 1-3, the refined aromatic oligomers obtained by the refining method provided by this invention in Examples 1-12 have lower catalyst content and ash content. Specifically, the refined aromatic oligomers obtained by the method provided by this invention meet the following requirements: catalyst content ≤ 200 mg / kg; ash content ≤ 200 mg / kg; C element content 90.5-93 wt%; H element content 7-8 wt%. Furthermore, the refined aromatic oligomers obtained by the refining method provided by this invention also have a higher yield.

[0125] Compared to Example 4, Example 1, by controlling the polymerization reaction conditions within the preferred protection range, yielded refined aromatic oligomers with lower catalyst content and ash content, as well as higher yield.

[0126] Compared to Examples 5 and 12, Example 1, by adjusting the weight ratio of the first solvent to the aromatic oligomer within the preferred protection range, produces a refined aromatic oligomer with lower catalyst content and ash content.

[0127] Compared to Example 6, Example 1, by adjusting the weight ratio of the second solvent and crude aromatic oligomer within the preferred protection range, produces refined aromatic oligomers with lower catalyst content and ash content.

[0128] Compared to Example 6, Example 1, by adjusting the type of the second solvent within the preferred protection range, yielded a refined aromatic oligomer with lower catalyst content and ash content.

[0129] Compared to Examples 8-11, Example 1, by controlling the second extract to sequentially perform alkali washing, acid washing, and water washing, and ensuring that the alkali washing, acid washing, and water washing processes are within the preferred protection range, yields refined aromatic oligomers with both lower catalyst content and ash content.

[0130] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for purifying aromatic oligomers, characterized in that, The refining method includes the following steps: (1) The aromatic oligomer containing the catalyst and the first solvent are subjected to a first extraction, and the first extract is subjected to a first distillation to obtain crude aromatic oligomer; wherein, the catalyst content in the aromatic oligomer is 2-30 wt%; the viscosity is 100-500 mPa·s; the ash content is 2-30 wt%; the conditions for the first extraction include: temperature of 15-35℃ and time of 0.1-10h; the weight ratio of the first solvent to the aromatic oligomer is 1-10:1; wherein, under the action of the catalyst, the aromatic-rich raw material is subjected to a polymerization reaction to obtain the aromatic oligomer, and the catalyst is a solid acid catalyst and is selected from at least one of AlCl3, CuCl2, ZnCl2, FeCl3 and ZrCl4; (2) The crude aromatic oligomer and the second solvent are subjected to a second extraction. The second extract is then subjected to alkali washing, acid washing and water washing in sequence, and then subjected to a second distillation to obtain the refined aromatic oligomer. The conditions for the second extraction include: temperature of 15-40℃ and time of 0.1-10h. The first solvent is selected from oxygen-containing organic compounds capable of forming complexes with the catalyst in the aromatic oligomer, and is selected from at least one of furan, furfural, and tetrahydrofuran; the second solvent is selected from at least one of benzene, toluene, and xylene.

2. The refining method according to claim 1, wherein, The aromatic-rich raw material is selected from high-aromatic oils and / or aromatic compounds; wherein the high-aromatic oils meet the following requirements: aromatic content ≥ 50 wt%; solid content ≤ 20 mg / kg; total heteroatom content ≤ 3 wt%. And / or, the weight ratio of the catalyst to the aromatic-rich feedstock is 0.1-20:

100.

3. The refining method according to claim 2, wherein, The high-aromatic oils meet the following requirements: aromatic content of 50-99 wt%; solid content of 1-10 mg / kg; and total heteroatom content of 0.1-1 wt%. And / or, the weight ratio of the catalyst to the aromatic-rich feedstock is 5-10:

100.

4. The refining method according to claim 1, wherein, In step (1), the weight ratio of the first solvent to the aromatic oligomer is 2-6:

1.

5. The refining method according to claim 1, wherein, In step (1), the weight ratio of the first solvent to the aromatic oligomer is 2.5-5.5:

1.

6. The refining method according to claim 1, wherein, In step (1), the viscosity of the crude aromatic oligomer is <100 mPa·s; the catalyst content is <2 wt%; the first solvent content is ≤5 wt%; and the ash content is <2 wt%. And / or, the conditions for the first extraction include: a temperature of 20-30°C; and a time of 0.5-2 h.

7. The refining method according to claim 6, wherein, In step (1), the viscosity of the crude aromatic oligomer is 50-90 mPa·s; the catalyst content is 0.1-1 wt%; the first solvent content is 0.1-3.5 wt%; and the ash content is 0.1-1.5 wt%.

8. The refining method according to claim 1, wherein, In step (2), the weight ratio of the second solvent to the crude aromatic oligomer is 1-5:

1.

9. The refining method according to claim 8, wherein, In step (2), the weight ratio of the second solvent to the crude aromatic oligomer is 1-2:

1.

10. The refining method according to claim 1, wherein, In step (2), the conditions for the second extraction include: a temperature of 20-30℃ and a time of 0.5-2h; And / or, the conditions for the second distillation include: a temperature of 110-150°C; and a pressure of -90 to 100 kPa.

11. The refining method according to claim 1, wherein, In step (2), the conditions for the second distillation include: a temperature of 120-140℃ and a pressure of -90 to 50 kPa.

12. The refining method according to claim 1, wherein, The alkaline washing process includes: contacting the second extract with an alkaline solution and performing alkaline washing to obtain an alkaline washed product; The pickling process includes: contacting the alkaline washing product with an acid solution and performing pickling to obtain the pickled product; The washing process includes: contacting the acid-washed product with water and washing it to obtain a washed product.

13. The refining method according to claim 12, wherein, The weight ratio of the alkaline solution to the second extract is 0.5-2:1; the number of alkaline washes is 1-8. And / or, the weight ratio of the acid solution to the second extract is 0.5-2:1; the number of acid washes is 1-5; And / or, the weight ratio of water to the second extract is 0.5-2:1; the number of water washes is 1-5.

14. The refining method according to claim 13, wherein, The weight ratio of the alkaline solution to the second extract is 0.8-1.5:1; the number of alkaline washes is 1-3. And / or, the weight ratio of the acid solution to the second extract is 0.8-1.5:1; the acid washing is performed 1-2 times; And / or, the weight ratio of water to the second extract is 0.8-1.5:1; the number of water washes is 1-2.

15. The refining method according to any one of claims 1-14, wherein, In step (2), the refined aromatic oligomer contains a catalyst content ≤200mg / kg, an ash content ≤200mg / kg, a carbon content of 90.5-93wt%, and a hydrogen content of 7-8wt%.

16. The refining method according to any one of claims 1-14, wherein, Application of the refined aromatic oligomers obtained by the refining method in carbon materials.

17. The refining method according to claim 16, wherein, The refined aromatic oligomers obtained by the refining method are used in mesophase pitch, coated pitch, impregnated pitch, conductive carbon black, and hydrogen fuel cell catalyst supports.

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