An electronic-grade fine benzene monomer deep purification method and electronic-grade fine benzene monomer

Abstract

The application belongs to the technical field of high-end electronic chemical purification and refining, and discloses a deep purification and refining method of electronic-grade refined acenaphthylene monomer and the electronic-grade refined acenaphthylene monomer. The method takes industrial-grade crude acenaphthylene melt phase as raw material, and sequentially undergoes acid eutectic solvent liquid-liquid extraction, macroporous chelating resin chromatography in non-polar aliphatic hydrocarbon, ultrasonic-assisted ethanol / ultrapure water gradient anti-solvent crystallization, low-temperature centrifugal elution and vacuum drying treatment. The acid eutectic solvent can efficiently remove sulfur, nitrogen heterocycle and polar oxide; the chelating resin can remove trace metal ions in a salt-free water washing system; the ultrasonic, anti-solvent composition change and the cooling process are synchronously performed to control the supersaturation, crystal nucleus generation and mother liquor entrainment. The obtained electronic-grade refined acenaphthylene has a gas chromatography purity of more than 99.99%, the total sulfur and total nitrogen are both lower than 1.0 ppm, any single metal ion in sodium, potassium, iron, copper, chromium and nickel is lower than 10 ppb, and the acenaphthylene recovery rate is not less than 92%.

Description

Technical Field

[0001] This invention belongs to the field of high-end electronic chemical purification and refining technology, specifically relating to a method for deep purification and refining of electronic-grade acenaphthene monomer and electronic-grade acenaphthene monomer. Background Technology

[0002] Anenabinoids are important polycyclic aromatic compounds that can serve as a basic raw material for electronic chemicals, high-purity aromatic monomers, and fine chemical intermediates. For electronic-grade applications, sulfur and nitrogen heterocyclic compounds and trace metal ions in refined acenabinoids can affect subsequent reactions, material stability, and electrical insulation-related indicators. Therefore, it is necessary to further control the impurity content beyond ordinary industrial-grade refining.

[0003] The main industrial source of acenaphthene is coal tar wash oil fraction. Industrial-grade crude acenaphthene typically has a purity of 80% to 95%, containing homologues and impurities with similar boiling points, polarities, and molecular sizes. Sulfur-containing heterocyclic compounds such as benzothiophene have boiling points and molecular configurations similar to acenaphthene and may precipitate along with acenaphthene crystals during recrystallization. Nitrogen heterocyclic compounds such as quinoline, isoquinoline, and indole are highly polar and difficult to remove stably by ordinary water washing or single-solvent recrystallization. Trace metal ions such as sodium, potassium, iron, copper, nickel, and chromium may enter the product through polar impurities, inorganic detergents, or equipment contact. Therefore, the preparation of electronic-grade refined acenaphthene requires simultaneous control of both organic and metal ion impurities.

[0004] Among the existing publicly available technologies, CN100336788C discloses a method for obtaining a fraction with an acenaphthene content of 65% to 75% through single-tower vacuum distillation using coal tar wash oil as raw material, followed by recrystallization with anhydrous ethanol or ethyl acetate to obtain a product with an acenaphthene purity of over 99%. CN101177372A discloses a method for melting an acenaphthene fraction with an acenaphthene content of 50% to 80%, adding toluene, xylene, or ethanol as a crystallization solvent, and then obtaining a high-purity acenaphthene product of 98.5% to 99.9% through cooling crystallization, filtration, and centrifugal washing. While these routes can increase the acenaphthene content, they mainly rely on distillation and recrystallization with common organic solvents, and do not specifically address the simultaneous control of ppm-level sulfur and nitrogen heterocyclic compounds and ppb-level metal ions.

[0005] US6664433B1 discloses a method for purifying aromatic hydrocarbons, targeting aromatic hydrocarbons derived from coal tar or petroleum, such as naphthalene, methylnaphthalene, anthracene, acenaphthene, and fluorene. This method uses formaldehyde or a formaldehyde-generating compound, optionally combined with phenolic substances, in the presence of an acidic catalyst to convert sulfur- and nitrogen-containing impurities that are difficult to separate by distillation or crystallization into high-boiling-point oligomers. Unreacted aromatic hydrocarbons are then recovered by evaporation or distillation. This method can reduce some sulfur and nitrogen impurities, but it requires chemical reactions and high-temperature separation steps, and may result in the loss of the target aromatic hydrocarbons.

[0006] CN104762100B and WO2016155136A1, among other documents, disclose the use of acidic eutectic solvents to extract and remove nitrogen-containing compounds from oil products. While these disclosures provide a technical background for nitrogen removal using acidic eutectic solvents, they typically treat liquid oils such as naphtha, gasoline, kerosene, diesel, lubricating oil base oils, or wax oils. They do not address the molten phase of crude acenaphthene, which is solid at room temperature, nor do they disclose the subsequent use of non-polar chelating resins for demetallization and ultrasonic gradient antisolvent crystallization after acidic eutectic solvent extraction to obtain electronic-grade refined acenaphthene.

[0007] CN117427359A discloses a system apparatus and method for extracting electronic-grade chemicals from coal tar wash oil fractions, wherein the acenaphthene-related refining unit includes distillation, melt crystallization, and adsorption separation. This technology focuses on the systematic separation of coal tar wash oil fractions and the extraction of electronic-grade chemicals, but does not disclose the sequential combination of molten crude acenaphthene acidic eutectic solvent pre-extraction, continuous demetallization with a non-polar macroporous chelating resin, and ultrasound-assisted ethanol / ultrapure water gradient antisolvent crystallization used in this invention.

[0008] CN114591133B discloses a method for preparing high-quality acenaphthene, which involves steps such as dissolution in n-hexane, washing with a 50% calcium chloride aqueous solution, washing with a 10% sodium hydroxide aqueous solution, water washing, drying, and freeze crystallization. This method targets acenaphthene rather than acenaphthene, and the strong salt / strong alkali multi-stage water washing route carries the risk of introducing inorganic ions such as calcium and sodium into the product system, making it unsuitable for direct use as a ppb-level metal control process for electronic-grade refined acenaphthene.

[0009] Therefore, it is still necessary to provide a process for deep refining of crude acenaphthene for industrial use, so as to sequentially control sulfur and nitrogen impurities, trace metal ions, and mother liquor entrainment during crystallization, and obtain refined acenaphthene monomers that meet electronic grade requirements with a high recovery rate. Summary of the Invention

[0010] Therefore, the purpose of this invention is to provide a method for deep purification and refining of electronic-grade acenaphthene monomers, as well as electronic-grade acenaphthene monomers, aiming to overcome the technical defects of existing acenaphthene refining processes, such as incomplete impurity removal, low product recovery rate, easy introduction of secondary metal impurities, and severe entrainment in the crystallization mother liquor. This invention utilizes a stepwise coupled process of "first desulfurization and nitrogen removal, then metal removal, and simultaneous controlled crystallization" to simultaneously achieve deep removal of sulfur and nitrogen impurities and trace metal ions under conditions of no aldehyde / phenol condensation and no strong salt / strong alkali washing, producing ultra-high purity acenaphthene that meets electronic-grade specifications in high yield.

[0011] To achieve the above objectives, the present invention provides the following technical solution: A method for deep purification of electronic-grade acenaphthene monomers, using the molten phase of industrial-grade crude acenaphthene as the processing target, specifically includes the following steps: (a) Liquid-liquid extraction with acidic eutectic solvent: Molten industrial-grade crude acenaphthene is mixed and extracted with an acidic eutectic solvent in a liquid-liquid two-phase process. After standing and separating the layers, the acidic eutectic solvent phase enriched with impurities is separated, and the acenaphthene-rich organic precursor is collected. The acidic eutectic solvent is formed by the co-melting of quaternary ammonium salt-type hydrogen bond acceptors and acidic hydrogen bond donors. The acidic hydrogen bond donors and quaternary ammonium salt-type hydrogen bond acceptors in the acidic eutectic solvent can generate acid-base interactions, hydrogen bonding interactions, and polar dissolution interactions with nitrogen heterocycles, sulfur heterocycles, and polar oxides, allowing the above impurities to preferentially enter the acidic eutectic solvent phase. This step is set before crystallization to reduce the possibility of sulfur and nitrogen impurities co-precipitating or being carried away with the mother liquor during the subsequent crystal growth stage.

[0012] (b) Chelating and demetallization in a nonpolar system: The organic precursor obtained in step (a) is dissolved in a nonpolar aliphatic hydrocarbon solvent, and the resulting solution is continuously passed through an adsorption column packed with macroporous chelating resin. Alkali metal ions and transition metal ions in the solution are captured by the resin through coordination, and the column effluent is collected. This step is carried out in a non-aqueous, non-strong salt, and non-strong base system, avoiding the introduction of inorganic ions such as sodium and calcium into the system by traditional water washing, salt washing, or alkali washing. The iminodiacetic acid groups, aminophosphonic acid groups, or thiol functional groups on the resin backbone have a selective coordination and capture effect on metal ions, further reducing Na, K, Fe, Cu, Ni, Cr, and other metal ions to the ppb level before crystallization.

[0013] (c) Ultrasonic-assisted gradient antisolvent crystallization: The column effluent obtained in step (b) is placed in a crystallization vessel. While continuously applying an ultrasonic field, a polar antisolvent composed of anhydrous ethanol and ultrapure water is continuously added dropwise, and the temperature is simultaneously lowered. This allows the changes in antisolvent composition, the formation of supersaturation, and the crystal growth process to be controlled synchronously, resulting in a refined acenaphthene crystallization slurry. The synchronous changes in antisolvent composition, the formation of supersaturation, and the cooling process avoid fine crystal agglomeration and mother liquor entrainment caused by rapid precipitation. The ultrasonic field is used to disperse local supersaturated areas, regulate the crystal nucleus formation rate, and reduce the possibility of impurities being carried along with the crystals.

[0014] (d) Low-temperature centrifugation and vacuum drying: The crystallized slurry obtained in step (c) is centrifuged at low temperature. At the end of the centrifugation, the filter cake is washed through with a low-temperature ethanol / ultrapure water mixture. After collecting the wet crystals, they are dried under reduced pressure to obtain electronic grade acenaphthene monomer.

[0015] As a further improvement of the present invention, in step (a), the acidic eutectic solvent is prepared by eutectic melting of hydrogen bond acceptor and acidic hydrogen bond donor at 70°C to 90°C in a molar ratio of 1:2 to 1:4, wherein the quaternary ammonium salt type hydrogen bond acceptor is selected from at least one of choline chloride, tetraethylammonium chloride or benzyltriethylammonium chloride; and the acidic hydrogen bond donor is selected from at least one of p-toluenesulfonic acid, methanesulfonic acid, lactic acid or citric acid.

[0016] As a further improvement of the present invention, in step (a), the extraction temperature is 60℃~90℃, the extraction stirring time is 30~90 minutes, the mass ratio of the acidic eutectic solvent to industrial grade crude acenaphthene is 0.3:1~1:1, and the total sulfur and total nitrogen content in the organic phase precursor obtained after extraction is reduced by at least 95% compared with the industrial grade crude acenaphthene raw material.

[0017] As a further improvement of the present invention, in step (b), the aliphatic hydrocarbon nonpolar solvent is selected from at least one of cyclohexane, n-heptane, or isooctane; the mass ratio of the organic phase precursor to the aliphatic hydrocarbon nonpolar solvent is 1:2.5 to 1:5; the macroporous chelating resin is a macroporous polystyrene-divinylbenzene copolymer resin with an iminodiacetic acid group, an aminophosphonic acid group, or a mercapto functional group in its skeleton; the volume hourly space velocity of the continuous chromatography is 0.5 / h to 2.0 / h, and the adsorption temperature is 25℃ to 50℃; in the column effluent after step (b), the content of any single metal ion among Na, K, Fe, Cu, Ni, and Cr is ≤20 ppb.

[0018] As a further improvement of the present invention, in step (c), the polar antisolvent is a mixture of anhydrous ethanol and ultrapure water with a resistivity ≥18 MΩ·cm, with a mass ratio of 75:25 to 90:10; the total volume ratio of the aliphatic hydrocarbon nonpolar solvent to the polar antisolvent is 1:0.8 to 1:1.5; the dropping rate of the polar antisolvent is 0.01 / min to 0.05 / min of the volume of the aliphatic hydrocarbon nonpolar solvent; the temperature of the crystallization vessel is reduced from 45℃ to 55℃ to -5℃ to 5℃ at a rate of 0.2℃ / min to 0.5℃ / min; the ultrasonic frequency of the ultrasonic field is 20kHz to 40kHz, and the ultrasonic power density is 0.1W / cm². 2 ~0.5W / cm 2 .

[0019] As a further improvement of the present invention, in step (d), the temperature of low-temperature centrifugation is -10℃ to 5℃, and the relative centrifugal force is 2000g to 4000g; the mass ratio of anhydrous ethanol to ultrapure water with a resistivity ≥18MΩ·cm in the low-temperature ethanol / ultrapure water mixed eluent is 80:20, the temperature of the eluent is 0℃ to 5℃, and the amount of eluent used is 15% to 30% of the filter cake mass; the absolute pressure of vacuum drying is <1000Pa, the drying temperature is 70℃ to 85℃, and the drying time is 3 to 5h.

[0020] As a further improvement of the present invention, the method does not use formaldehyde, formaldehyde-generating compounds, or acid-catalyzed condensation and turgoring reactions of aldehydes and phenols as steps for removing sulfur and nitrogen impurities, and does not use calcium chloride aqueous solution, sodium hydroxide aqueous solution, or other high-concentration inorganic salt aqueous solution / strong alkali aqueous solution to perform multi-stage liquid-liquid washing on the acenaphthene organic phase.

[0021] As a further improvement of the present invention, based on the quality of acenaphthene in industrial-grade crude acenaphthene, the acenaphthene recovery rate of electronic-grade refined acenaphthene monomers obtained through the overall process from step (a) to step (d) is ≥92%.

[0022] The electronic-grade acenaphthene monomer prepared by any of the methods described above has a gas chromatographic purity ≥99.99%, a total sulfur content <1.0 ppm, a total nitrogen content <1.0 ppm, and a single metal ion impurity content of Na, K, Fe, Cu, Ni, or Cr <10 ppb.

[0023] As a further improvement of the present invention, based on the characteristic ions or characteristic peaks of hydrogen bond acceptors and acidic hydrogen bond donors in the acidic eutectic solvent used, the residual amount of acidic eutectic solvent is ≤0.5ppm, the total amount of residual aliphatic hydrocarbon nonpolar solvent and ethanol is ≤100ppm, and the crystal grain size D50 is 80μm~300μm.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects: (1) Compared with ordinary distillation or ordinary solvent recrystallization, the present invention sets up acidic eutectic solvent extraction and non-polar chelating resin chromatography before crystallization, so that sulfur and nitrogen impurities and metal ions are separately and deeply controlled before crystal formation, avoiding the co-precipitation and entrainment of impurities during the crystallization stage, and realizing the simultaneous removal of organic and inorganic impurities.

[0025] (2) Compared with the aldehyde-phenol condensation heavy ionization route, this invention does not use the acid-catalyzed heavy ionization reaction involving formaldehyde, aldehydes or phenols as the main means of impurity removal, thus avoiding the chemical transformation loss of the target acenaphthene molecule, eliminating the safety and environmental hazards of formaldehyde use, and achieving effective control of metal ions.

[0026] (3) Compared with the strong salt / strong alkali multi-stage water washing route, the present invention is carried out in a non-water, non-strong salt, and non-strong alkali system throughout the process, avoiding the risk of secondary introduction of inorganic ions such as sodium and calcium into the product by high-concentration inorganic water washing agents such as calcium chloride and sodium hydroxide, and is more suitable for the ppb-level metal control requirements of electronic grade acenaphthene.

[0027] (4) Compared with the rapid antisolvent precipitation route, the present invention achieves the mild formation of supersaturation and effective control of crystal nuclei by applying an ultrasonic field, continuously adding antisolvent, and simultaneously controlling the temperature program. This significantly reduces the risk of intercrystalline mother liquor entrainment and sulfur and nitrogen impurities precipitating with crystals, while improving crystal quality and solvent residue control.

[0028] (5) Compared with existing acidic eutectic solvent oil extraction technology, this invention adapts the process to the crude acenaphthene molten phase which is solid at room temperature, and innovatively couples acidic eutectic solvent extraction, non-polar system chelating resin demetallization and ultrasonic gradient antisolvent crystallization in sequence to form a complete process chain for the preparation of electronic grade refined acenaphthene.

[0029] (6) The gas chromatographic purity of the electronic-grade acenaphthene monomer obtained by this invention can reach more than 99.99%, the total sulfur and total nitrogen are both less than 1.0 ppm, the single metal ion of sodium, potassium, iron, copper, chromium and nickel is less than 10 ppb, and the acenaphthene recovery rate is not less than 92%, which meets the requirements of high-end electronic chemical applications. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments and comparative examples. The listed embodiments are used to illustrate possible implementations of the present invention and should not be construed as limiting the scope of protection.

[0031] Unless otherwise specified, the water used in the examples was ultrapure water with a resistivity of 18 MΩ·cm; metal ion detection was performed using ICP-MS; total sulfur was detected using GC-SCD; total nitrogen was detected using GC-AED; monomer purity was detected using GC-FID; and residual acidic eutectic solvent was calculated by ion chromatography or LC-MS based on characteristic ions or peaks of hydrogen bond acceptors and acidic hydrogen bond donors.

[0032] Example 1: A method for deep purification of electronic-grade acenaphthene monomers, using the molten phase of industrial-grade crude acenaphthene as the processing target, specifically includes the following steps: (a) Liquid-liquid extraction with acidic eutectic solvent: Choline chloride and p-toluenesulfonic acid were added to a PFA-lined synthesis vessel at a molar ratio of 1:2 and stirred at 80°C until a homogeneous and transparent liquid was formed, yielding an acidic eutectic solvent. 100 kg of industrial-grade crude acenaphthene was heated to 85°C to melt. The purity of the raw material was tested to be 88.50%, with total sulfur of 2400 ppm, total nitrogen of 1800 ppm, Na of 120 ppb, and Fe of 450 ppb. The acidic eutectic solvent was added at a mass ratio of 0.5:1 to industrial-grade crude acenaphthene, and the mixture was stirred and extracted at 85°C for 45 minutes. After standing for 1 hour to separate the layers, the lower acidic eutectic solvent phase was separated, and the upper organic precursor phase was collected.

[0033] (b) Chelation and demetallization of nonpolar systems: The organic phase precursor obtained in step (a) is dissolved in cyclohexane at a mass ratio of 1:3 at 50°C, and passed through a continuous chromatography column packed with macroporous chelating resin containing iminodiacetic acid functional groups at 40°C and volume hourly space velocity of 1.0 / h. The column effluent is collected.

[0034] (c) Ultrasonic-assisted gradient antisolvent crystallization: The column effluent obtained in step (b) is introduced into an ultra-clean crystallizer, and ultrasonication is initiated at 45°C with an ultrasonic frequency of 25 kHz and a power density of 0.25 W / cm³. 2 Anhydrous ethanol / ultrapure water mixed antisolvent was continuously added dropwise at a rate equivalent to 2% of the nonpolar solvent volume per minute, with a mass ratio of 85:15; simultaneously, the temperature was lowered from 45°C to 0°C at a rate of 0.3°C / min to obtain a crystallized slurry.

[0035] (d) Low-temperature centrifugal washing and vacuum drying: The crystalline slurry obtained in step (c) was centrifuged at -5°C with a relative centrifugal force of approximately 2800 g. At the end of the centrifugation, the filter cake was washed with an ethanol / ultrapure water mixture (80:20 by mass) at 2°C, with the washing volume being 20% ​​of the wet filter cake mass. After washing, the mixture was further centrifuged for 10 minutes, and then vacuum dried at 75°C and an absolute pressure of 800 Pa for 4 hours to obtain electronic-grade refined acenaphthene monomer. The acenaphthene recovery rate was 93.1%.

[0036] Example 2: A method for deep purification of electronic-grade acenaphthene monomers, using the molten phase of industrial-grade crude acenaphthene as the processing target, specifically includes the following steps: (a) Liquid-liquid extraction with acidic eutectic solvent: An acidic eutectic solvent was prepared by eutectic melting tetraethylammonium chloride and lactic acid at a molar ratio of 1:3 at 85°C. 100 kg of industrial-grade crude acenaphthene with a purity of 91.20%, total sulfur of 1400 ppm, total nitrogen of 950 ppm, Na of 95 ppb, and Fe of 320 ppb was heated to 75°C and melted. The acidic eutectic solvent was added at a mass ratio of 0.4:1 to the industrial-grade crude acenaphthene, and the mixture was stirred and extracted for 60 minutes. After standing and phase separation, the upper organic phase precursor was collected.

[0037] (b) Chelation and demetallization of nonpolar system: The organic phase precursor obtained in step (a) is dissolved in n-heptane at a mass ratio of 1:4 and passed through a chromatography column packed with macroporous chelating resin of aminophosphonic acid functional group at 35°C and volume hourly space velocity of 0.8 / h. The column eluent is collected.

[0038] (c) Ultrasonic-assisted gradient antisolvent crystallization: The column effluent obtained in step (b) is introduced into an ultra-clean crystallizer and crystallized at 50°C, ultrasonic frequency of 35kHz, and ultrasonic power density of 0.30W / cm³. 2Under ultrasonic conditions, a mixed antisolvent of ethanol / ultrapure water with a mass ratio of 80:20 was added dropwise at a rate of 0.03 / min (volume of nonpolar aliphatic hydrocarbon solvent), and the temperature was lowered from 50℃ to -2℃ at a rate of 0.4℃ / min to obtain a crystallized slurry.

[0039] (d) Low-temperature centrifugation and vacuum drying: The crystallized slurry obtained in step (c) was centrifuged at 2°C and a relative centrifugal force of 3000g. At the end, the filter cake was washed with a mixed ethanol / ultrapure water at a mass ratio of 80:20 and a temperature of 1°C. The amount of rinsing solution was 18% of the mass of the filter cake. Then, it was vacuum dried at an absolute pressure of 500Pa and a temperature of 78°C for 3 hours to obtain electronic-grade acenaphthene monomer with a yield of 94.2%.

[0040] Example 3: A method for deep purification of electronic-grade acenaphthene monomers, using the molten phase of industrial-grade crude acenaphthene as the processing target, specifically includes the following steps: (a) Liquid-liquid extraction with acidic eutectic solvent: An acidic eutectic solvent was prepared by eutectic melting benzyltriethylammonium chloride and p-toluenesulfonic acid at a molar ratio of 1:2 at 80°C. 100 kg of crude coal tar with a purity of 85.00%, total sulfur of 3200 ppm, total nitrogen of 2450 ppm, Na of 180 ppb, and Fe of 580 ppb was melted at 90°C. The acidic eutectic solvent was added at a mass ratio of 0.8:1 to the crude acenaphthene, and the mixture was stirred and extracted for 90 minutes. After standing and separating, the upper organic phase precursor was collected.

[0041] (b) Chelation and demetallization of nonpolar systems: The organic phase precursor obtained in step (a) is dissolved in isooctane at a mass ratio of 1:5 and passed through a macroporous chelating resin column packed with thiol functional groups at 50°C and a volume hourly space velocity of 1.5 / h. The column effluent is collected.

[0042] (c) Ultrasonic-assisted gradient antisolvent crystallization: The column effluent obtained in step (b) was subjected to ultrasonic-assisted crystallization at 55°C, with an ultrasonic frequency of 40 kHz and a power density of 0.15 W / cm³. 2 A 90:10 mixture of ethanol and ultrapure water as a reverse solvent was added dropwise at a rate of 0.015 drops / min, and the temperature was lowered to 5°C at a rate of 0.25°C / min to obtain a crystallized slurry.

[0043] (d) Low-temperature centrifugation and vacuum drying: The crystallized slurry obtained in step (c) was centrifuged at 4°C and a relative centrifugal force of 2500g. The filter cake was washed with an ethanol / ultrapure water wash solution at a mass ratio of 80:20 and a temperature of 3°C. The wash solution amount was 25% of the filter cake mass. Then, it was vacuum dried at an absolute pressure of 900Pa and a temperature of 80°C for 5 hours to obtain electronic-grade refined acenaphthene monomer. The acenaphthene recovery rate was 92.5%.

[0044] Example 4: A method for deep purification of electronic-grade acenaphthene monomers, using the molten phase of industrial-grade crude acenaphthene as the processing target, specifically includes the following steps: (a) Liquid-liquid extraction with acidic eutectic solvent: An acidic eutectic solvent was prepared by eutectic melting choline chloride and citric acid at a molar ratio of 1:2.5 at 85°C. 100 kg of pre-distilled industrial-grade crude acenaphthene with a purity of 94.50%, total sulfur of 980 ppm, total nitrogen of 640 ppm, Na of 60 ppb, and Fe of 190 ppb was heated to 80°C to melt. The acidic eutectic solvent was added at a mass ratio of 0.3:1 to the industrial-grade crude acenaphthene. The mixture was stirred and extracted for 30 minutes. After standing and phase separation, the organic phase precursor was collected.

[0045] (b) Chelation and demetallization of nonpolar systems: The organic phase precursor obtained in step (a) was dissolved in cyclohexane at a mass ratio of 1:3.5 and passed through a macroporous chelating resin column with iminodiacetic acid functional groups at 30°C and a volume hourly space velocity of 0.6 / h. The column effluent was collected.

[0046] (c) Ultrasonic-assisted gradient antisolvent crystallization: The column effluent obtained in step (b) was subjected to ultrasonic treatment at 45°C, an ultrasonic frequency of 20 kHz, and an ultrasonic power density of 0.45 W / cm³. 2 Under ultrasonic conditions, a polar antisolvent consisting of ethanol (75:25 by mass ratio) and ultrapure water with a resistivity ≥18 MΩ·cm was added dropwise at a rate of 0.04 / min (volume of nonpolar aliphatic hydrocarbon solvent) and cooled from 45℃ to -5℃ at a rate of 0.45℃ / min to obtain a crystallized slurry.

[0047] (d) Low-temperature centrifugation and vacuum drying: The crystallized slurry obtained in step (c) was centrifuged at -10°C and a relative centrifugal force of about 3600g. The filter cake was washed with a mixed ethanol / ultrapure water at a mass ratio of 80:20 and a temperature of 1°C. The amount of rinsing solution was 15% of the mass of the filter cake. Then, it was vacuum dried at an absolute pressure of 400Pa and a temperature of 76°C for 3.5 hours to obtain electronic-grade refined acenaphthene monomer. The acenaphthene recovery rate was 95.0%.

[0048] Comparative Example 1: Preparation of acenaphthene via aldehyde-phenol condensation and heavy distillation route 100 kg of industrial-grade crude acenaphthene from the same batch as in Example 1 was placed in a reaction vessel, and 25 kg of paraformaldehyde, 40 kg of phenol, and 1.2% p-toluenesulfonic acid were added. The reaction was carried out at 180°C for 3 hours. After the reaction, the light components were distilled off by raising the temperature, followed by vacuum distillation at 265°C and 1300 Pa absolute pressure. The top fraction was collected and cooled with methanol to crystallize. The obtained refined acenaphthene had a gas chromatographic purity of 99.910%, with total sulfur of 4.5 ppm, total nitrogen of 3.2 ppm, Na of 120 ppb, and Fe of 85 ppb. The overall recovery rate of acenaphthene was 72.3%.

[0049] Comparative Example 2: Preparation of refined acenaphthene via a multi-stage strong salt / strong alkali washing route 10.2 g of industrial-grade crude acenaphthene from the same batch as in Example 1 was added to 100 mL of anhydrous n-hexane and dissolved at 50 °C. The solution was washed three times with 50% calcium chloride aqueous solution, three times with 10% sodium hydroxide aqueous solution, and three times with ultrapure water. It was then dried and concentrated with anhydrous magnesium sulfate and frozen at -15 °C for 12 hours. The obtained refined acenaphthene had a gas chromatographic purity of 99.700%, with total sulfur of 22.0 ppm, total nitrogen of 15.0 ppm, Na of 45 ppb, and Fe of 32 ppb. The acenaphthene recovery rate was 81.5%.

[0050] Comparative Example 3: Preparation of Acenamethanil via a rapid methanol antisolvent precipitation route 100 kg of industrial-grade crude acenaphthene from the same batch as in Example 1 was dissolved in 300 kg of toluene. After acid washing and phase separation, a large volume of ice-cold methanol was rapidly added to precipitate the refined acenaphthene under high supersaturation conditions. The precipitate was filtered, washed with a methanol / water mixture, and vacuum dried. The obtained refined acenaphthene had a gas chromatographic purity of 99.820%, with total sulfur of 18.0 ppm, total nitrogen of 8.0 ppm, Na of 25 ppb, and Fe of 18 ppb. The acenaphthene recovery rate was 84.8%.

[0051] Comparative Example 4: Preparation of Acenamethanil by Omitting Acidic Eutectic Solvent Extraction Except for omitting the acidic eutectic solvent extraction in step (a), the remaining operations were the same as in Example 1. The same batch of industrial-grade crude acenaphthene was directly dissolved in cyclohexane, followed by macroporous chelating resin chromatography, ultrasonic-assisted gradient antisolvent crystallization, and low-temperature centrifugal drying. The obtained refined acenaphthene had a gas chromatographic purity of 99.835%, with total sulfur of 16.5 ppm, total nitrogen of 9.4 ppm, Na of 4 ppb, and Fe of 3 ppb. The acenaphthene recovery rate was 94.4%. This result indicates that even without acidic eutectic solvent extraction before crystallization, sulfur and nitrogen impurities will still remain during the crystallization process.

[0052] Comparative Example 5: Preparation of refined acenaphthene by omitting macroporous chelating resin chromatography Except for skipping step (b) of the macroporous chelating resin continuous chromatography, the remaining operations were the same as in Example 1. The organic phase precursor, after extraction with an acidic eutectic solvent, was directly subjected to ultrasonic-assisted gradient antisolvent crystallization. The obtained acenaphthene gas chromatographic purity was 99.988%, with total sulfur at 0.8 ppm, total nitrogen at 0.6 ppm, Na at 76 ppb, Fe at 64 ppb, and Cu at 9 ppb, and an acenaphthene recovery rate of 93.5%. These results indicate that acidic eutectic solvent extraction can reduce sulfur and nitrogen impurities, but is insufficient to stably achieve ppb-level metal control.

[0053] Comparative Example 6: Preparation of the ultrasonic field was omitted. Except for step (c), which did not apply an ultrasonic field, the remaining operations were the same as in Example 1, with the antisolvent addition and cooling rates remaining unchanged. The obtained purified acenaphthene had a gas chromatographic purity of 99.942%, total sulfur of 2.8 ppm, total nitrogen of 1.9 ppm, Na of 5 ppb, and Fe of 4 ppb. The acenaphthene recovery rate was 91.2%, and the crystal particle size D50 was 52 μm. These results indicate that even with only acidic eutectic solvent extraction and macroporous chelating resin chromatography, if ultrasonic dispersion and crystal nucleus control are lacking during the crystallization process, an increase in fine crystals, mother liquor entrainment, and reverse banding of sulfur and nitrogen impurities may still occur.

[0054] Comparative Example 7: Preparation of purified acenaphthene by rapid antisolvent addition without simultaneous gradient cooling Except for step (c), where the ethanol / ultrapure water antisolvent is added rapidly in one step and the crystallization system is directly cooled from 45°C to 0°C, the remaining operations are the same as in Example 1. The obtained acenaphthene has a gas chromatographic purity of 99.905%, total sulfur of 4.2 ppm, total nitrogen of 2.5 ppm, Na of 6 ppb, and Fe of 5 ppb. The acenaphthene recovery rate is 89.8%, the total amount of residual aliphatic hydrocarbon nonpolar solvent and ethanol is 280 ppm, and the crystal particle size D50 is 35 μm. These results indicate that when the composition of the polar antisolvent, the formation of supersaturation, and the cooling process are not controlled synchronously, both crystal quality and impurity control decrease.

[0055] The test data summary and analysis are shown in Table 1: Table 1. Key quality data of the acenaphthene products obtained in the examples and comparative examples.

[0056] As shown in Table 1, Examples 1-4 simultaneously meet the requirements of gas chromatographic purity not less than 99.99%, total sulfur less than 1.0 ppm, total nitrogen less than 1.0 ppm, single metal ion less than 10 ppb, residual acidic eutectic solvent not more than 0.5 ppm, residual solvent not more than 100 ppm, and yield not less than 92%.

[0057] Comparative Example 1 shows that while the aldehyde-phenol condensation and turbidity route can reduce some sulfur and nitrogen impurities, the acenaphthene recovery rate decreases significantly, and metal ions are not effectively controlled. Comparative Example 2 shows that the multi-stage strong salt / strong alkali washing route cannot achieve the simultaneous control of sulfur, nitrogen, and metal ions in electronic-grade refined acenaphthene. Comparative Example 3 shows that rapid antisolvent precipitation cannot effectively avoid the entrainment of sulfur and nitrogen impurities.

[0058] Comparative Examples 4 to 7 are single-variable controls. In Comparative Example 4, after omitting acidic eutectic solvent extraction, although metal ions could be reduced through resin, sulfur and nitrogen impurities still significantly exceeded the limits. In Comparative Example 5, after omitting chelating resin, sulfur and nitrogen levels were close to those of the example, but metal ions exceeded the limits. In Comparative Example 6, after omitting the ultrasonic field, crystal particle size decreased and sulfur and nitrogen residues increased. In Comparative Example 7, after not using simultaneous control of antisolvent addition and cooling, residual solvent, particle size, and sulfur and nitrogen residues all deteriorated. The above results demonstrate that the technical effect of this invention comes from the sequential coupling of acidic eutectic solvent extraction, non-polar chelating resin demetallization, and ultrasonic gradient antisolvent crystallization, rather than the conventional replacement of any single step.

[0059] The acidic eutectic solvent used in the method of this invention can be recycled through phase separation and regeneration; the aliphatic hydrocarbon nonpolar solvent and ethanol can be recovered through conventional distillation; the macroporous chelating resin can be regenerated after acid washing, ultrapure water washing, and organic solvent replacement. This method can be used for the electronic-grade deep refining of industrial-grade crude acenaphthene, and can also be used as a post-processing unit after obtaining crude acenaphthene from the front-end separation of coal tar washing oil.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, component splitting or combination, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for deep purification and refining of electronic-grade acenaphthene monomers, characterized in that, The process involves treating the molten phase of industrial-grade coarse acenaphthene, specifically including the following steps: (a) Liquid-liquid extraction with acidic eutectic solvent: Molten industrial-grade crude acenaphthene is mixed with an acidic eutectic solvent for liquid-liquid two-phase extraction. After standing and separating the layers, the acidic eutectic solvent phase enriched with impurities is separated, and the organic phase precursor rich in acenaphthene is collected. The acidic eutectic solvent is formed by the co-melting of quaternary ammonium salt type hydrogen bond acceptor and acidic hydrogen bond donor. (b) Chelating and demetallization in nonpolar systems: The organic phase precursor obtained in step (a) is dissolved in a nonpolar solvent of aliphatic hydrocarbons, and the resulting solution is continuously passed through an adsorption column packed with macroporous chelating resin, so that alkali metal ions and transition metal ions in the solution are captured by the resin through coordination, and the column effluent is collected. (c) Ultrasonic-assisted gradient antisolvent crystallization: The column effluent obtained in step (b) is placed in a crystallization vessel. While continuously applying an ultrasonic field, a polar antisolvent composed of anhydrous ethanol and ultrapure water is continuously added dropwise, and the temperature is simultaneously lowered. This allows the changes in the composition of the antisolvent, the formation of supersaturation, and the crystal growth process to be controlled simultaneously, resulting in a refined acenaphthene crystallization slurry. (d) Low-temperature centrifugation and vacuum drying: The crystallized slurry obtained in step (c) is centrifuged at low temperature. At the end of the centrifugation, the filter cake is washed through with a low-temperature ethanol / ultrapure water mixture. After collecting the wet crystals, they are dried under reduced pressure to obtain electronic grade acenaphthene monomer.

2. The method for deep purification and refining of electronic-grade acenaphthene monomers according to claim 1, characterized in that: In step (a), the acidic eutectic solvent is prepared by eutectic melting of hydrogen bond acceptor and acidic hydrogen bond donor at 70°C to 90°C in a molar ratio of 1:2 to 1:

4. The quaternary ammonium salt type hydrogen bond acceptor is selected from at least one of choline chloride, tetraethylammonium chloride or benzyltriethylammonium chloride; the acidic hydrogen bond donor is selected from at least one of p-toluenesulfonic acid, methanesulfonic acid, lactic acid or citric acid.

3. The method for deep purification and refining of electronic-grade acenaphthene monomers according to claim 1, characterized in that: In step (a), the extraction temperature is 60℃~90℃, the extraction stirring time is 30~90 minutes, the mass ratio of the acidic eutectic solvent to industrial grade crude acenaphthene is 0.3:1~1:1, and the total sulfur and total nitrogen content in the organic phase precursor obtained after extraction is reduced by at least 95% compared with the industrial grade crude acenaphthene raw material.

4. The method for deep purification and refining of electronic-grade acenaphthene monomers according to claim 1, characterized in that: In step (b), the aliphatic hydrocarbon nonpolar solvent is selected from at least one of cyclohexane, n-heptane, or isooctane; the mass ratio of the organic phase precursor to the aliphatic hydrocarbon nonpolar solvent is 1:2.5 to 1:5; the macroporous chelating resin is a macroporous polystyrene-divinylbenzene copolymer resin with an iminodiacetic acid group, an aminophosphonic acid group, or a mercapto functional group in its skeleton; the volume hourly space velocity of the continuous chromatography is 0.5 / h to 2.0 / h, and the adsorption temperature is 25℃ to 50℃; in the column effluent after step (b), the content of any single metal ion among Na, K, Fe, Cu, Ni, and Cr is ≤20 ppb.

5. The method for deep purification and refining of electronic-grade acenaphthene monomers according to claim 1, characterized in that: In step (c), the polar antisolvent is a mixture of anhydrous ethanol and ultrapure water with a resistivity ≥18 MΩ·cm, with a mass ratio of 75:25 to 90:10; the total volume ratio of the aliphatic hydrocarbon nonpolar solvent to the polar antisolvent is 1:0.8 to 1:1.5; the dropping rate of the polar antisolvent is 0.01 to 0.05 times the volume of the aliphatic hydrocarbon nonpolar solvent; the temperature of the crystallization vessel is reduced from 45℃ to 55℃ to -5℃ to 5℃ at a rate of 0.2℃ to 0.5℃ to 0.5℃ per minute; the ultrasonic frequency of the ultrasonic field is 20kHz to 40kHz, and the ultrasonic power density is 0.1W / cm². 2 ~0.5W / cm 2 .

6. The method for deep purification and refining of electronic-grade acenaphthene monomers according to claim 1, characterized in that: In step (d), the temperature of low-temperature centrifugation is -10℃ to 5℃, and the relative centrifugal force is 2000g to 4000g; the mass ratio of anhydrous ethanol to ultrapure water with a resistivity ≥18MΩ·cm in the low-temperature ethanol / ultrapure water mixed eluent is 80:20, the temperature of the eluent is 0℃ to 5℃, and the amount of eluent used is 15% to 30% of the filter cake mass; the absolute pressure of vacuum drying is <1000Pa, the drying temperature is 70℃ to 85℃, and the drying time is 3 to 5h.

7. The method for deep purification and refining of electronic-grade acenaphthene monomers according to claim 1, characterized in that: This method does not use formaldehyde, formaldehyde-generating compounds, or acid-catalyzed condensation and turgoring reactions of aldehydes and phenols as steps for removing sulfur and nitrogen impurities, nor does it use calcium chloride aqueous solution, sodium hydroxide aqueous solution, or other high-concentration inorganic salt aqueous solution / strong alkali aqueous solution to perform multi-stage liquid-liquid washing on the acenaphthene organic phase.

8. A method for deep purification and refining of electronic-grade acenaphthene monomers according to any one of claims 1-7, characterized in that: Based on the quality of acenaphthene in industrial-grade crude acenaphthene, the acenaphthene recovery rate of electronic-grade refined acenaphthene monomers obtained through the overall process from step (a) to step (d) is ≥92%.

9. The electronic-grade acenaphthene monomer prepared by the method according to any one of claims 1-7, characterized in that: The electronic-grade acenaphthene monomer has a gas chromatographic purity ≥99.99%, a total sulfur content <1.0 ppm, a total nitrogen content <1.0 ppm, and a single metal ion impurity content of Na, K, Fe, Cu, Ni, or Cr <10 ppb.

10. The electronic-grade refined acenaphthene monomer according to claim 9, characterized in that: Based on the characteristic ions or peaks of hydrogen bond acceptors and acidic hydrogen bond donors in the acidic eutectic solvent used, the residual amount of acidic eutectic solvent is ≤0.5ppm, the total amount of residual aliphatic hydrocarbon nonpolar solvent and ethanol is ≤100ppm, and the crystal grain size D50 is 80μm~300μm.

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