Method for removing biphenyl and extracting high-purity acenaphthene from azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material

Abstract

The invention provides a method for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material, which comprises the following steps: (1) dissolving the acenaphthene-dibenzofuran-fluorene-biphenyl material in organic alcohol to obtain a dissolved solution; and (2) sequentially carrying out cooling crystallization and solid-liquid separation on the dissolved solution in the step (1) to obtain a first liquid phase without biphenyl or a first solid phase without biphenyl, thereby completing the breaking of the azeotropic system. According to the method, the acenaphthene-dibenzofuran-fluorene-biphenyl material is dissolved in the organic alcohol, then the cooling crystallization mode is adopted, the technical effects of removing biphenyl and purifying acenaphthene can be achieved at the same time, due to the fact that biphenyl is removed, an azeotropic system does not exist among the materials any more, high-purity acenaphthene, dibenzofuran and fluorene products can be obtained from follow-up materials through rectification separation, and the method is suitable for industrial production. The application prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of separation and purification, in particular to a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene. Background Art

[0002] As global industrial demand continues to grow, demands for the purity and yield of high-value-added chemicals in the coal tar wash oil fraction, such as acenaphthene, dibenzofuran, and fluorene, are also increasing. The coal tar wash oil fraction is a key intermediate product obtained after the initial distillation of coal tar. Its composition includes a rich supply of polycyclic aromatic hydrocarbons, particularly the heavy oil fraction. The coal tar wash oil fraction can be generally divided into a light wash oil fraction (230-250°C), a medium wash oil fraction (250-260°C), and a heavy wash oil fraction (260-300°C) based on temperature ranges (temperature ranges may vary slightly in different literature). The heavy oil fraction, a key component of the wash oil fraction, contains acenaphthene, fluorene, and a variety of other valuable chemicals. These chemicals are widely used in the electronics and information technology industry, including photoresists, OLEDs, and high-performance polymer materials. Therefore, research to improve their purity and yield is crucial. This initiative will help meet industrial and market demands and promote the continued development of related fields.

[0003] The applicant has conducted research on typical domestic coal tar wash oil fractions, and has patents CN117244262A and CN117427359A for these research. These results have successfully developed a system and method for extracting high-purity or electronic-grade chemicals from these fractions. These methods have gained industry recognition, effectively improving the purification efficiency and purity of chemicals such as acenaphthene and fluorene. However, when applying these techniques to actual production in different processes, the applicant has encountered more complex challenges. In particular, when processing the more complex wash oil fractions produced by specific coking processes, new azeotropic issues caused by substances such as dimethylbiphenyl have been discovered.

[0004] The difference between traditional coking processes and specialized coking processes lies primarily in the reaction conditions and reactant selection. Specialized coking processes utilize specialized catalysts, reaction temperatures, pressures, and different raw material combinations, resulting in more complex wash oil fractions. For example, a coking company, due to process innovation, employed specialized reaction conditions and catalysts in its coking process, which triggered the dimerization of benzene molecules, leading to the appearance of a new biphenyl isomer, dimethylbiphenyl, in the coal tar wash oil fraction. Because dimethylbiphenyl shares similar physical properties with acenaphthene, fluorene, and other compounds, forming an azeotropic system, it is difficult to effectively separate them during distillation extraction.

[0005] Based on the problems found in the previous research, the applicant filed this patent application.

[0006] Behind this patent application is an in-depth exploration of an important issue in the special coking process. The special coking process is an important technological change in the coking industry, which uses special reaction conditions and catalysts to improve product quality and yield.

[0007] For example, compared to traditional coking processes, specific coking processes involve the control of more factors, such as coal type selection, heating rate, final temperature, and holding time. These factors directly affect the composition and properties of coal tar and its wash oil fractions. For example, the azeotropic effects caused by new biphenyl isomers lead to many challenges in improving the purity of traditional purification methods when processing wash oil fractions with azeotropic characteristics.

[0008] This patent application was filed based on the problems encountered in processing wash oil fractions produced by a specific coking process. The applicant conducted in-depth research on the characteristics of compounds produced by this specific coking process, combined with the processing requirements of wash oil fractions with specific compositions, to develop a more flexible and efficient purification technology to address the high-purity extraction of azeotropic and diverse compounds. Summary of the Invention

[0009] To address the above technical problems, the present invention provides a method for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl mixture. This method uses a suitable organic alcohol to dissolve the acenaphthene-dibenzofuran-fluorene-biphenyl mixture and then cools and crystallizes it. In this special azeotropic system, biphenyl is removed and high-purity acenaphthene with a purity of ≥99% is obtained, laying the foundation for the subsequent preparation of electronic-grade acenaphthene, dibenzofuran, and fluorene.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] The present invention provides a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene, the method comprising:

[0012] (1) dissolving acenaphthene-dibenzofuran-fluorene-biphenyl material in an organic alcohol to obtain a dissolved solution;

[0013] (2) The organic solution in step (1) is sequentially subjected to cooling crystallization and solid-liquid separation to obtain a first liquid phase from which biphenyl has been removed or a first solid phase from which biphenyl has been removed, thereby completing the breaking of the azeotropic system.

[0014] The present invention is based on the actual observation and in-depth analysis of the application of the two patent technologies of CN117244262A and CN117427359A. In actual application, although the technical solutions of the first two patents can handle most azeotropic problems, there are limitations in efficiency and purity for certain new azeotropic phenomena encountered in the raw materials produced by the unique coking process, such as the problems caused by dimethyl biphenyl. Therefore, based on the practical experience and existing limitations of the first two patents, the present invention further conducts in-depth research and specifically proposes a more effective solution. The present invention is specifically aimed at the above-mentioned newly discovered azeotropic problem. By selecting specific solvents and optimizing crystallization conditions, it specifically solves the azeotropic phenomenon of substances such as dimethyl biphenyl, thereby effectively improving the purification efficiency and purity of the target products acenaphthene and fluorene. This method is based on CN117244262A and CN117427359A. Through in-depth analysis of the complexity of the raw materials and the particularity of the azeotropic problem, the solvent and crystallization conditions are innovatively selected and optimized, thereby providing higher adaptability and efficiency in processing more complex raw materials.

[0015] Therefore, the causal relationship between the present invention and patents CN117244262A and CN117427359A is reflected in the fact that it is based on the practical application of the technical solutions of the first two patents, and is carried out in-depth research and innovative development to address new challenges and limitations encountered. By targeted solutions to specific problems, the present invention not only embodies continuous technological innovation, but also further broadens the scope of application and effectiveness of purification technology when dealing with different raw materials. This causal relationship and technological innovation clearly demonstrate that the present invention is based on further in-depth research and innovation based on practical problems.

[0016] Therefore, the method of removing biphenyl from the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene according to the present invention preferably further comprises:

[0017] (3) washing, cooling, crystallizing, and drying the first solid phase after the biphenyl removal azeotrope breaking to remove the residual solvent to obtain high-purity acenaphthene with a purity of ≥99%;

[0018] (4) Using the technology described in patent CN117244262A or CN117427359A, the first liquid phase after the de-biphenyl azeotropic breaking is subjected to efficient distillation separation to obtain high-purity fluorene with a purity of ≥99% and dibenzofuran with a purity of ≥99%.

[0019] Preferably, the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material in step (1) is derived from a heavy fraction oil at 260-300° C. in a coal tar wash oil fraction.

[0020] Preferably, the composition of the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material includes 30-60 wt% of acenaphthene, 10-25 wt% of dibenzofuran, 10-30 wt% of fluorene, 0.5-30 wt% of biphenyl organic matter and 0.1-10 wt% of other impurities.

[0021] When the inventors were studying the deep processing and extraction of high-value-added chemicals such as acenaphthene and fluorene from the heavy oil fraction of coal tar washing oil, they found that it was impossible to obtain products such as acenaphthene, fluorene, and dibenzofuran with a purity of ≥98% using the traditional distillation separation technology commonly used in industry.

[0022] The present researchers further discovered that the dimethyl biphenyl-acenaphthene binary azeotrope and dimethyl biphenyl-acenaphthene-fluorene ternary azeotrope exist in the heavy fraction of the wash oil at 260-300°C, wherein the phase equilibrium curve of dimethyl biphenyl-acenaphthene is shown in FIG. Figure 1 As shown, the residual curve of the dimethylbiphenyl-acenaphthene-fluorene ternary system is shown in Figure 2 As shown, Figure 2 Medium biphenyl refers to dimethyl biphenyl in biphenyl organic compounds. Figure 1 The phase diagram of dimethylbiphenyl and acenaphthene has a common highest point, that is, the mixture forms a negative azeotrope at a pressure of 120 kPa and cannot be separated by conventional distillation or fractionation. Figure 2 The ternary system exhibits a binary azeotropic point (dimethylbiphenyl-acenaphthene) and a ternary azeotropic point (dimethylbiphenyl-acenaphthene-fluorene) at a pressure of 120 kPa. Rectification regions exist near each of these azeotropic points. Furthermore, a liquid-liquid equilibrium region exists between biphenyl, acenaphthene, and fluorene, indicating that these three components form two liquid phase regions in the liquid phase. Due to the presence of binary and ternary azeotropic systems, high-purity separation of acenaphthene and fluorene cannot be achieved solely through conventional industrial distillation separation techniques. Therefore, the present invention utilizes solvent crystallization in combination with separation.

[0023] Preferably, the content of acenaphthene in the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material in step (1) is 30 to 60 wt%, for example, it can be 30 wt%, 40 wt%, 43 wt%, 45 wt%, 47 wt%, 49 wt%, 52 wt%, 54 wt%, 56 wt%, 58 wt% or 60 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0024] Preferably, the content of biphenyl organic matter in the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material is 0.5 to 30 wt%, for example, it can be 0.5 wt%, 3 wt%, 7 wt%, 10 wt%, 13 wt%, 16 wt%, 20 wt%, 23 wt%, 26 wt% or 30 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0025] Preferably, the content of fluorene in the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material is 10 to 30 wt%, for example, it can be 10 wt%, 13 wt%, 15 wt%, 17 wt%, 19 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt% or 30 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0026] Preferably, the content of dibenzofuran in the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material is 10 to 25 wt%, for example, it can be 10 wt%, 12 wt%, 14 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 22 wt%, 24 wt% or 25 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0027] Preferably, the biphenyl organic matter in the acenaphthene-dibenzofuran-fluorene-biphenyl material includes any one of dimethylbiphenyl isomers, biphenyl, methylbiphenyl, dimethylbiphenyl or 2-methylbiphenyl, or a combination of at least two thereof.

[0028] Preferably, the organic alcohol in step (1) is an organic alcohol, preferably a monoalcohol.

[0029] Preferably, the organic alcohol has 1 to 12 carbon atoms, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, and preferably 1 to 5. Preferably, the organic alcohol is methanol and / or ethanol.

[0030] Since the mixture of (acenaphthene + fluorene + dibenzofuran + dimethylbiphenyl) is an aromatic compound, the aromatic rings contained therein can form hydrogen bonds with the hydroxyl groups in the alcohol solvent. This intermolecular interaction formed by hydrogen bonding will promote the formation of a stronger binding force between the solvent and the target component. The binding force between the organic alcohol and the target component is shown in Table 1.

[0031] Table 1

[0032] solvent Acenaphthene / (kJ / mol) Fluorene / (kJ / mol) Dibenzofuran / (kJ / mol) Biphenyl / (kJ / mol) Methanol -9.94 -1.68 -4.45 -11.85 ethanol -7.42 -1.79 -4.74 -12.59 Pentanol -8.64 -2.08 -5.49 -14.61 Propanol -5.35 -1.29 -3.41 -9.06 Hexanol -7.06 -1.71 -4.49 -11.94 Octanol -8.01 -1.93 -5.12 -13.61 Decyl alcohol -8.24 -1.99 -5.28 -14.01 Dodecanol -8.19 -2.22 -5.89 -15.69 Caprylyl glycol -7.66 -1.85 -4.90 -13.02

[0033] According to Table 1, methanol, ethanol, and pentanol have relatively high absolute values ​​of attractive interaction energy with acenaphthene, while octanol, dodecanol, and octanediol have relatively high absolute values ​​of attractive interaction energy with biphenyl. However, long-chain alcohols such as octanol, dodecanol, and octanediol are highly toxic and expensive, making them unsuitable for large-scale industrial applications. For these reasons, short-chain alcohols are preferred as crystallization solvents in the present invention.

[0034] Preferably, the mass ratio of the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material to the organic alcohol in step (1) is 1:(1-2), for example, it can be 1:1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0035] Preferably, the dissolving in step (1) comprises: mixing the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and the organic alcohol, and heating and refluxing to obtain a dissolved solution.

[0036] Preferably, the heating reflux temperature is 120-160°C, for example, it can be 120°C, 125°C, 129°C, 134°C, 138°C, 143°C, 147°C, 152°C, 156°C or 160°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Preferably, the heating and reflux are carried out under stirring conditions.

[0038] Preferably, the rotation speed of the heating reflux is 200-500 r / min, for example, it can be 200 r / min, 235 r / min, 265 r / min, 300 r / min, 335 r / min, 365 r / min, 400 r / min, 430 r / min, 465 r / min or 500 r / min, but is not limited to the listed values. Other values ​​not listed in this range are also applicable.

[0039] Preferably, the heating reflux time is 15 to 60 minutes, for example, it can be 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes or 60 minutes, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0040] Preferably, the cooling rate of the cooling crystallization in step (2) is 0.5 to 5 ° C / min, for example, it can be 0.5 ° C / min, 1 ° C / min, 1.5 ° C / min, 2 ° C / min, 2.5 ° C / min, 3 ° C / min, 3.5 ° C / min, 4 ° C / min, 4.5 ° C / min or 5 ° C / min, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0041] Preferably, the endpoint temperature of the cooling crystallization is 20-25°C, for example, it can be 20°C, 20.6°C, 21.2°C, 21.7°C, 22.3°C, 22.8°C, 23.4°C, 23.9°C, 24.5°C or 25°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In the present invention, the rate and endpoint temperature of the cooling crystallization are both critical, and have a significant impact on the removal effect of biphenyl and the purity and yield of acenaphthene. It is preferred to control the cooling rate and endpoint temperature of the cooling crystallization within the above ranges. In combination with the selection of organic alcohol, the removal effect of biphenyl can be further improved.

[0043] Preferably, when the organic alcohol is methanol and / or ethanol, the content of biphenyl in the first solid phase is ≤50 ppm, and / or the content of acenaphthene in the first solid phase is ≥96 wt %.

[0044] Preferably, when the organic alcohol is pentanol, the content of biphenyl in the first liquid phase is ≤10 wt %, and / or the content of acenaphthene in the first liquid phase is ≥66 wt %.

[0045] Preferably, the method further comprises: (3) washing the first solid phase to obtain a washing liquid; cooling the washing liquid for crystallization and solid-liquid separation to obtain a second liquid phase and a second solid phase, the second solid phase is dried, and the biphenyl content of either the second liquid phase or the second solid phase is ≤1wt%.

[0046] The present invention further recovers materials in the washing liquid, thereby better improving the yield of acenaphthene.

[0047] Preferably, the washing detergent comprises ethanol.

[0048] Preferably, the liquid-to-solid ratio of the washing is 1 to 10:1 ml / g, for example, it can be 1:1 ml / g, 2:1 ml / g, 3:1 ml / g, 4:1 ml / g, 5:1 ml / g, 6:1 ml / g, 7:1 ml / g, 8:1 ml / g, 9:1 ml / g or 10:1 ml / g, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0049] Preferably, the cooling rate of the cooling crystallization is 0.5 to 5°C / min, for example, it can be 0.5°C / min, 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] Preferably, the endpoint temperature of the cooling crystallization is 20-25°C, for example, it can be 20°C, 20.6°C, 21.2°C, 21.7°C, 22.3°C, 22.8°C, 23.4°C, 23.9°C, 24.5°C or 25°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0051] As a preferred technical solution of the present invention, the method comprises the following steps:

[0052] (1) mixing the acenaphthene-dibenzofuran-fluorene-biphenyl material and the organic alcohol in a mass ratio of 1:(1-2) and heating and refluxing at 120-160° C. for 15-60 min at a speed of 200-500 r / min to obtain a dissolved solution;

[0053] Wherein, the organic alcohol is methanol and / or ethanol;

[0054] (2) The dissolved solution in step (1) is cooled to 20-25° C. at a cooling rate of 0.5-5° C. / min for crystallization, and then subjected to solid-liquid separation to obtain a first solid phase from which biphenyl has been removed, wherein the biphenyl content in the first solid phase is ≤50 ppm, and the acenaphthene content in the first solid phase is ≥96 wt %, thereby breaking the azeotropic system;

[0055] (3) washing the first solid phase in step (2) to obtain a washing liquid; cooling the washing liquid to 20-25° C. at a cooling rate of 0.5-5° C. / min for cooling crystallization, and then performing solid-liquid separation and drying to obtain a second liquid phase and a second solid phase, wherein the biphenyl content in the second solid phase is ≤50 ppm, and the acenaphthene content in the second solid phase is ≥99.0 wt%.

[0056] Optionally, (4) the first liquid phase of step (3) is distilled and separated using the high-efficiency distillation separation technology described in patent CN117244262A or CN117427359A to obtain high-purity fluorene with a purity of ≥99% and high-purity dibenzofuran with a purity of ≥99%, and industrial biphenyl with a purity of ≥90%.

[0057] The present invention has no particular limitation on the solid-liquid separation in the above process. Any device and method for solid-liquid separation known to those skilled in the art can be used, and can also be adjusted according to the actual process. For example, it can be filtration, centrifugation or sedimentation separation, or a combination of different methods.

[0058] Compared with the prior art, the present invention has at least the following beneficial effects:

[0059] The method provided by the present invention is for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material. By deeply analyzing the complexity of the raw materials and the particularity of the azeotropic problem, the solvent and crystallization conditions are innovatively selected and optimized, thereby achieving the removal of biphenyl. Under the optimal conditions, the biphenyl content can be reduced to within the detection limit, achieving the effect of breaking the azeotropic effect, and providing the possibility for the high-purity separation of fluorene and dibenzofuran. Moreover, by optimizing the organic alcohol and optimizing the cooling crystallization process, the purity of acenaphthene can be directly increased to ≥99%. Furthermore, the subsequent separation cost of the acenaphthene-dibenzofuran-fluorene-biphenyl material can be reduced, and the subsequent distillation separation can be used to achieve the production of electronic-grade acenaphthene and electronic-grade fluorene. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is the phase equilibrium curve of dimethylbiphenyl-acenaphthene.

[0061] Figure 2 This is the residual curve of the dimethylbiphenyl-acenaphthene-fluorene system.

[0062] Figure 3 The present invention provides a flow chart of a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene. DETAILED DESCRIPTION

[0063] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0064] It should be understood that, in the description of the present invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0065] As a specific embodiment of the present invention, a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene is provided. Figure 3 , the method comprises the following steps:

[0066] (1) mixing the acenaphthene-dibenzofuran-fluorene-biphenyl material and the organic alcohol in a mass ratio of 1:(1-2) and heating and refluxing at 120-160° C. for 15-60 min at a speed of 200-500 r / min to obtain a dissolved solution;

[0067] Wherein, the organic alcohol is methanol and / or ethanol;

[0068] (2) The dissolved solution in step (1) is cooled to 20-25° C. at a cooling rate of 0.5-5° C. / min for crystallization, and then subjected to solid-liquid separation to obtain a first liquid phase and a first solid phase from which biphenyl has been removed, wherein the biphenyl content in the first solid phase is ≤50 ppm, and the acenaphthene content in the first solid phase is ≥96 wt %, thereby breaking the azeotropic system;

[0069] (3) washing the first solid phase in step (2) and drying the solid phase to obtain an acenaphthene product and a washing liquid; the washing liquid enters a distillation tower, undergoes distillation separation, and obtains a recovered solvent at the top of the tower, which is recycled as a crystallization solvent (organic alcohol); the residual oil at the bottom of the tower is incorporated into the first liquid phase produced in step (2), and the remaining substances are further separated and extracted; the acenaphthene content in the acenaphthene product is ≥99.0wt%, and the biphenyl content is ≤50ppm.

[0070] (4) Step (2): The first liquid phase enters a high-efficiency distillation separation system. After high-efficiency distillation in each tower, high-purity fluorene with a purity of ≥99% and dibenzofuran with a purity of ≥99% can be obtained. At the same time, industrial biphenyl with a purity of ≥90% can be obtained. The remaining residual oil is recycled as a benzene washing agent.

[0071] The acenaphthene-dibenzofuran-fluorene-biphenyl material in the following examples and comparative examples is derived from a 260-300°C coal tar wash oil fraction from a specific coking process, and its composition is: 35% acenaphthene, 20% fluorene, 20% dibenzofuran, 20% biphenyl, and 5% other impurities.

[0072] Example 1

[0073] This embodiment provides a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene, the method comprising the following steps:

[0074] (1) According to the mass ratio of azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material to ethanol being 1:1.5, the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and ethanol were mixed in a four-necked bottle, placed in an oil bath, and slowly heated at a rate of 2°C / min. After the solid in the bottle was completely dissolved, the heating temperature was raised to 160°C, the liquidus temperature reached 120°C, and the whole was heated and refluxed for 50 minutes at a heating and reflux speed of 500 r / min to obtain a dissolved solution;

[0075] (2) transferring the four-necked bottle containing the dissolved solution in step (1) into a water bath, cooling the solution to 25°C at a cooling rate of 0.5°C / min for crystallization, and then filtering the solution to obtain a first liquid phase and a first solid phase;

[0076] (3) Washing the first solid phase in step (2) with ethanol to obtain a solid phase and a washing liquid. Filtering and drying the solid phase to obtain an acenaphthene product and a washing liquid. The washing liquid enters a distillation tower, undergoes distillation separation, and obtains a recovered solvent at the top of the tower, which is recycled as a crystallization solvent. The residue in the tower bottom is incorporated into step (2) to continue separating and extracting the remaining substances;

[0077] (4) subjecting the first liquid phase of step (2) to efficient distillation separation to ultimately obtain fluorene, dibenzofuran and biphenyl products.

[0078] The first liquid phase and the first solid phase obtained after crystallization in step (2), the acenaphthene product and the washing liquid obtained after washing in step (3), and the fluorene, dibenzofuran and biphenyl products in step (4) were taken respectively, and the content of each component (acenaphthene, dibenzofuran, fluorene, dimethylbiphenyl) was quantitatively analyzed by gas chromatography. The results are shown in Table 2.

[0079] Table 2

[0080]

[0081] Example 2

[0082] This embodiment provides a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene, the method comprising the following steps:

[0083] (1) According to the mass ratio of azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material to methanol being 1:2, the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and methanol were mixed in a four-necked bottle, placed in an oil bath, and slowly heated at a rate of 2.5°C / min. After the solid in the bottle was completely dissolved, the heating temperature was raised to 150°C, and the liquidus temperature reached 122°C. The whole was heated and refluxed for 60 minutes at a heating and reflux speed of 200 r / min to obtain a dissolved solution;

[0084] (2) transferring the four-necked bottle containing the dissolved solution of step (1) into a water bath, cooling the solution to 25°C at a cooling rate of 0.5°C / min for crystallization, and then filtering the solution to obtain a first liquid phase and a first solid phase;

[0085] (3) Washing the first solid phase in step (2) with ethanol to obtain a solid phase and a washing liquid. Filtering and drying the solid phase to obtain an acenaphthene product and a washing liquid. The washing liquid enters a distillation tower, undergoes distillation separation, and obtains a recovered solvent at the top of the tower, which is recycled as a crystallization solvent. The residue in the tower bottom is incorporated into step (2) to continue separating and extracting the remaining substances;

[0086] (4) subjecting the first liquid phase of step (2) to efficient distillation separation to ultimately obtain fluorene, dibenzofuran and biphenyl products.

[0087] The first liquid phase and the first solid phase obtained after crystallization in step (2), the acenaphthene product and the washing liquid obtained after washing in step (3), and the fluorene, dibenzofuran and biphenyl products in step (4) were taken respectively, and the content of each component (acenaphthene, dibenzofuran, fluorene, dimethylbiphenyl) was quantitatively analyzed by gas chromatography. The results of the dissolved solution are shown in Table 3.

[0088] Table 3

[0089]

[0090] Example 3

[0091] This embodiment provides a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene, the method comprising the following steps:

[0092] (1) According to the mass ratio of azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material (40wt% acenaphthene, 25wt% dibenzofuran, 30wt% fluorene, 5wt% dimethylbiphenyl) to ethanol being 1:1.0, the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and ethanol were mixed in a four-necked bottle, placed in an oil bath, and slowly heated at a rate of 3°C / min. After the solid in the bottle was completely dissolved, the heating temperature was raised to 160°C, the liquidus temperature reached 120°C, and the whole was heated under reflux for 50min at a heating and reflux speed of 250r / min to obtain a dissolved solution;

[0093] (2) transferring the four-necked bottle containing the dissolved solution in step (1) into a water bath, cooling the solution to 25°C at a cooling rate of 0.5°C / min for crystallization, and then filtering the solution to obtain a first liquid phase and a first solid phase;

[0094] (3) Washing the first solid phase in step (2) with ethanol to obtain a solid phase and a washing liquid. Filtering and drying the solid phase to obtain an acenaphthene product and a washing liquid. The washing liquid enters a distillation tower, undergoes distillation separation, and obtains a recovered solvent at the top of the tower, which is recycled as a crystallization solvent. The residue in the tower bottom is incorporated into step (2) to continue separating and extracting the remaining substances;

[0095] (4) subjecting the first liquid phase of step (2) to efficient distillation separation to ultimately obtain fluorene, dibenzofuran and biphenyl products.

[0096] The first liquid phase and the first solid phase obtained after crystallization in step (2), the acenaphthene product and the washing liquid obtained after washing in step (3), and the fluorene, dibenzofuran and biphenyl products in step (4) were taken respectively, and the content of each component (acenaphthene, dibenzofuran, fluorene, dimethylbiphenyl) was quantitatively analyzed by gas chromatography. The results of the dissolved solution are shown in Table 4.

[0097] Table 4

[0098]

[0099] Example 4

[0100] This example provides a method for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material. The method is the same as Example 1 except that methanol is replaced by propanol, hexanol, and ethylene glycol in sequence, and will not be repeated here.

[0101] Referring to Example 1, the first liquid phase, the first solid phase, the washing liquid, the acenaphthene product, the fluorene product, the dibenzofuran product and the fluorene product were respectively taken, and the content of each component (acenaphthene, dibenzofuran, fluorene, biphenyl) was quantitatively analyzed by gas chromatography. The results are shown in Table 5.

[0102] Table 5

[0103]

[0104]

[0105] As can be seen from Table 5, the present invention preferably uses methanol and / or ethanol as the crystallization solvent to achieve better biphenyl removal effect.

[0106] Example 5

[0107] This embodiment provides a method for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material. The method is the same as that in Example 1 except that the cooling rates are 10°C / min and 0.1°C / min respectively, and will not be repeated here.

[0108] Referring to Example 1, the first liquid phase, the first solid phase, the second liquid phase and the second solid phase were respectively taken, and the content of each component (acenaphthene, dibenzofuran, fluorene, dimethylbiphenyl) was quantitatively analyzed by gas chromatography. The results are shown in Table 6.

[0109] Table 6

[0110]

[0111]

[0112] As can be seen from Table 6, in the method provided by the present invention for removing biphenyl and extracting high-purity acenaphthene from the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material, when the cooling crystallization rate is too fast or too slow, the acenaphthene product after breaking the azeotropic state will contain trace amounts of biphenyl organic matter, making it difficult for the purity of the subsequent product separation to reach electronic grade.

[0113] Comparative Example 1

[0114] This comparative example provides a method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene. The method is the same as Example 1 except that methanol is replaced by formic acid, and the details are not repeated here.

[0115] Comparative Example 2

[0116] This comparative example provides a method for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material. The method is the same as Example 1 except that methanol is replaced by methyl formate, and will not be repeated here.

[0117] Comparative Example 3

[0118] This comparative example provides a method for removing biphenyl and extracting high-purity acenaphthene from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material. The method is the same as Example 1 except that methanol is replaced by acetone, and the details are not repeated here.

[0119] The results of Comparative Examples 1 to 3 are shown in Table 7.

[0120] Table 7

[0121]

[0122] In Tables 1 to 7, “ / ” indicates that there is no relevant data.

[0123] As can be seen from Table 7, Comparative Examples 1 to 3 are difficult to remove biphenyl from the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material due to improper selection of organic solvents. Since the azeotropic system is not destroyed, the purification effect of acenaphthene, fluorene and dibenzofuran products is poor, and high-purity products cannot be obtained. This shows that the present invention can efficiently remove biphenyl organics from the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material by selecting organic alcohol as the organic solvent, and has broad application prospects.

[0124] The present invention uses the above-described embodiments to illustrate the detailed features of the present invention. However, the present invention is not limited to the above-described detailed features, which does not mean that the present invention must rely on the above-described detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the selected technical features of the present invention, additions to auxiliary technical features, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for removing biphenyl from an azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and extracting high-purity acenaphthene, characterized in that: The method comprises: (1) dissolving the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material in an organic alcohol to obtain a dissolved solution; (2) cooling and crystallizing the dissolved solution in step (1), and then performing solid-liquid separation to obtain a first liquid phase from which biphenyl has been removed or a first solid phase from which biphenyl has been removed, thereby breaking the azeotropic system.

2. The method according to claim 1, characterized in that The azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material in step (1) is derived from a heavy distillate oil at 260-300° C. in a coal tar wash oil fraction; Preferably, the composition of the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material includes 30-60 wt% of acenaphthene, 10-25 wt% of dibenzofuran, 10-30 wt% of fluorene, 0.5-30 wt% of biphenyl organic matter and 0.1-10 wt% of other impurities; Preferably, the biphenyl organic compound includes any one of dimethylbiphenyl isomers, biphenyl, methylbiphenyl, dimethylbiphenyl or 2-methylbiphenyl, or a combination of at least two thereof.

3. The method according to claim 1 or 2, characterized in that The organic alcohol in step (1) is a monoalcohol; Preferably, the organic alcohol has 1 to 12 carbon atoms, preferably 1 to 5; Preferably, the organic alcohol is methanol and / or ethanol.

4. The method according to any one of claims 1 to 3, characterized in that The mass ratio of the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material to the organic alcohol in step (1) is 1:(1-2).

5. The method according to any one of claims 1 to 4, characterized in that The dissolving in step (1) includes: mixing the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and the organic alcohol, and heating and refluxing to obtain a dissolved solution.

6. The method according to claim 5, characterized in that The heating reflux temperature is 120-160°C; Preferably, the heating and reflux is carried out under stirring conditions; Preferably, the rotation speed of the heating reflux is 200 to 500 r / min; Preferably, the heating reflux time is 15 to 60 minutes.

7. The method according to any one of claims 1 to 6, characterized in that The cooling rate of the cooling crystallization in step (2) is 0.5-5°C / min; Preferably, the terminal temperature of the cooling crystallization is 20-25°C.

8. The method according to any one of claims 1 to 7, characterized in that When the organic alcohol is methanol and / or ethanol, the content of biphenyl in the first solid phase is ≤50 ppm, and / or the content of acenaphthene in the first solid phase is ≥96 wt %; Preferably, when the organic alcohol is pentanol, the content of biphenyl in the first liquid phase is ≤10 wt %, and / or the content of acenaphthene in the first liquid phase is ≥66 wt %.

9. The method according to any one of claims 1 to 8, characterized in that The method further comprises: (3) washing the first solid phase to obtain a washing liquid; cooling the washing liquid for crystallization and solid-liquid separation to obtain a second liquid phase and a second solid phase, wherein the biphenyl content of either the second liquid phase or the second solid phase is ≤1 wt%; Preferably, the washing detergent comprises ethanol; Preferably, the liquid-to-solid ratio of the washing is 1-10:1 ml / g; Preferably, the cooling rate of the cooling crystallization is 0.5 to 5°C / min; Preferably, the terminal temperature of the cooling crystallization is 20-25°C.

10. The method according to any one of claims 1 to 9, characterized in that The method comprises the following steps: (1) mixing the azeotropic acenaphthene-dibenzofuran-fluorene-biphenyl material and the organic alcohol in a mass ratio of 1:(1-2), heating and refluxing at 120-160° C. for 15-60 min at a speed of 200-500 r / min to obtain a dissolved solution; Wherein, the organic alcohol is methanol and / or ethanol; (2) The dissolved solution in step (1) is cooled to 20-25° C. at a cooling rate of 0.5-5° C. / min for crystallization, and then subjected to solid-liquid separation to obtain a first solid phase from which biphenyl has been removed, wherein the biphenyl content in the first solid phase is ≤50 ppm, and the acenaphthene content in the first solid phase is ≥96 wt %, thereby breaking the azeotropic system; (3) washing the first solid phase in step (2) to obtain a washing liquid; cooling the washing liquid to 20-25° C. at a cooling rate of 0.5-5° C. / min for cooling crystallization, and then performing solid-liquid separation to obtain a second liquid phase and a second solid phase, wherein the biphenyl content in the second solid phase is ≤50 ppm, and the acenaphthene content in the second solid phase is ≥99.0 wt%.

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