An electronic grade low carbon alcohol ester reaction refining purification device, method and application thereof

Abstract

The present application relates to the field of wet electronic, in particular to a kind of reaction refining purification device and its method and application of electronic-grade low carbon alcohol ester.The device is integrated reaction rectifying column, light removal column, extractive distillation column, high-theoretical-plate rectifying column, dynamic melt crystallizer, at least two levels of adsorption tower group and osmotic pervaporation membrane unit in order along material flow direction, constitute the full continuous purification chain of progressive, function decoupling.First, low carbon alcohol, acid raw material is obtained by reaction rectifying column, and light component impurities are removed by light removal column, then the azeotropic system is broken by extractive distillation to deeply remove water, and then the impurities with close boiling point are separated by rectifying column precise rectification;Subsequently, the content of near-boiling impurities with boiling point difference <3 ℃ is reduced to <0.01 ppm by melt crystallization;Then trace water, metal ions and polar organic matter are deeply removed by two-stage adsorption of molecular sieve and chelating resin;Finally, the product purity is stabilized to ≥99.995% by ultimate refining through osmotic pervaporation membrane unit.

Description

Technical Field

[0001] This invention relates to the field of wet electronics, and in particular to a reactive purification apparatus, method and application for electronic-grade low-carbon alcohol esters. Background Technology

[0002] Wet electronic chemicals are the "lifeblood" of high-end manufacturing fields such as semiconductors and display panels, and their purity directly determines the yield, device performance, and reliability of integrated circuits. Electronic-grade low-carbon alcohol esters, represented by formate and acetate esters, are widely used in key wet processes such as photolithography, cleaning, and stripping. As process nodes continue to shrink to 28 nanometers, 14 nanometers, and even more advanced 5 nanometers and below, the purity requirements of these solvents in the industry have approached the limits of physicochemical separation technology: not only must the purity of the main component be ≥99.995% and the water content be less than 50 ppm, but more importantly, the content of specific metal ions such as potassium (K), sodium (Na), iron (Fe), and copper (Cu) must be stably controlled below 0.1 ppb (parts per billion), while a near-zero limit is also set for the number of submicron particles.

[0003] However, upgrading from industrial-grade products to semiconductor-grade ultrapure solvents meeting SEMI G4 / G5 standards faces technical bottlenecks stemming from both thermodynamic separation limits and secondary contamination during the process. Taking ethyl acetate as an example, the mainstream industrial route of acetic acid-ethanol esterification inevitably introduces impurities such as water, ethanol, and butanone into the crude product. Water and ethanol form binary azeotropes with ethyl acetate, and when all three coexist, they further form a ternary azeotropic system. Simultaneously, ethyl acetate is partially miscible with water at room temperature. These physical properties make it extremely difficult to simultaneously achieve deep dehydration and azeotropic component removal using conventional distillation methods. Existing purification technologies all have significant drawbacks in the process of achieving electronic-grade purity: extractive distillation easily introduces new impurities and has high energy consumption for extractant recovery; conventional distillation struggles to overcome azeotropic composition limitations; adsorption methods lack selectivity for trace metal ions and have short breakthrough cycles; and a single technical route cannot systematically solve the coupling problem of azeotropic removal, near-boiling-point impurity separation, and deep removal of trace contaminants.

[0004] Among existing purification technologies, patent CN102731298A achieves a purity of only 99.53% after dehydration, washing, adsorption, and distillation, failing to remove trace metal ions and polar organic matter; patent CN102070445A employs three-tower distillation, achieving purification precision only at the industrial level, not meeting ppb-level metal ion control requirements; patent CN112299999A combines mixed adsorbents with atmospheric pressure distillation, achieving a purity of 99.99%, but with total impurities around 200 ppm, and operates intermittently, resulting in limited removal of azeotropes; patent CN104177257A uses 1,4-butanediol or glycerol extractive distillation to break up azeotropes, but the product purity is only about 99%, lacking an adsorption unit. Patent CN121537287A employs a combined process of distillation for coarse dehydration and molecular sieve / CuY molecular sieve adsorption for fine dehydration, achieving a product purity of ≥99.99%. However, this route struggles to overcome azeotropic composition limitations and is only applicable to the separation of methyl acetate with its specific composition, rather than to the separation of lower alcohol ester systems other than methyl acetate, such as ethyl acetate and methyl propionate. None of the aforementioned technologies systematically solve the three major challenges of azeotropic dehydration, near-boiling impurity separation, and deep removal of trace contaminants.

[0005] In summary, increasing product purity from 99.9% to 99.995% (reducing total impurities from 1000 ppm to 50 ppm) requires simultaneously addressing three major challenges: azeotropic dehydration, near-boiling impurity separation, and removal of trace metals / polar substances. Conventional methods such as ordinary distillation, extractive distillation, or single adsorption all suffer from drawbacks such as incomplete azeotropic removal, residual near-boiling impurities, and difficulty in achieving ppb levels of metal ions. Furthermore, these methods are often intermittent and inefficient. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as insufficient purity, difficulty in continuous production, and inability to deeply remove azeotropes, near-boiling point impurities, and trace metal ions / polar substances. This invention provides a reactive purification apparatus, method, and application for electronic-grade low-carbon alcohol esters. The apparatus and method aim to achieve efficient and continuous industrial production and systematically solve three major technical challenges: azeotropic dehydration, near-boiling point impurity separation, and deep removal of trace contaminants. This results in the stable production of ultra-high purity electronic-grade low-carbon alcohol esters that meet the requirements of advanced semiconductor processes (such as SEMI G4 / G5 levels). This invention effectively breaks through the technical bottleneck of solvent purification in high-end electronic manufacturing processes. The ultra-high purity solvent obtained can directly meet the stringent requirements of key wet processes such as photolithography and cleaning in advanced semiconductor processes and high-generation LCD panel manufacturing.

[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides an apparatus for the reactive purification of electronic-grade low-carbon alcohol esters, the apparatus comprising, in sequence along the material flow direction: Reactive distillation column: used to obtain crude low-carbon alcohol esters from low-carbon alcohol and acid raw materials through reactive distillation; Light component removal tower is used to remove light component impurities from crude low-carbon alcohol esters that have a boiling point difference of more than 20°C from the low-carbon alcohol esters. An extractive distillation column is used to remove ethanol and water, which form azeotropes with lower carbon alcohol esters, by extractive distillation. A distillation column, wherein the theoretical number of the distillation column is at least 100, is used to separate impurities whose boiling points differ from those of lower carbon alcohol esters by less than 20°C; The dynamic melt crystallizer (full name: dynamic falling film tower melt crystallizer, which belongs to existing technology) is used to separate low-carbon alcohol esters and impurities with similar boiling points (such as methyl ethyl ketone and methyl propionate) by utilizing the difference in freezing points. Specifically, through temperature-controlled crystallization and sweating operations, the content of impurities with a boiling point difference of <3℃ (near-boiling impurities) is further reduced to <0.01 ppm (taking ethyl acetate and its near-boiling point impurities present in the production process as examples, their freezing points are: ethyl acetate -83.6℃, ​​methyl ethyl ketone -86.6℃, methyl propionate -87.5℃). And an adsorption tower group, which consists of at least two adsorption towers connected in series, for removing trace amounts of moisture, dissolved metal ions and polar organic matter; specifically, the adsorption tower group is used to remove moisture to below 10 ppm and simultaneously adsorb and remove dissolved metal ions and polar organic matter.

[0008] Further, the lower carbon alcohol ester is at least one selected from ethyl formate, methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate.

[0009] Furthermore, the ethyl acetate has a normal boiling point of about 77°C, the ethyl formate has a boiling point of about 54.7°C, the methyl acetate has a boiling point of about 58°C, the methyl propionate has a boiling point of about 79.8°C, and the ethyl propionate has a boiling point of about 99.1°C.

[0010] Furthermore, the upper and middle sections of the reactive distillation column are provided with an acid (heavy component) inlet and the middle section is provided with an alcohol (light component) inlet. The acid and alcohol materials are in countercurrent contact with the loaded solid organic acid catalyst in the reaction section of the reactive distillation column, and generate crude low-carbon alcohol ester through esterification reaction. After the distillate from the top of the column is condensed and separated by a phase separator, the upper organic phase is sent as crude ester to the light component removal column, and the lower aqueous phase is discharged or recovered.

[0011] Furthermore, the operating conditions of the reactive distillation column are: top pressure 0.03 MPa~0.15 MPa, top temperature 65~79℃, bottom temperature 75~95℃, and reflux ratio 2~5:1.

[0012] Furthermore, the operating conditions of the reactive distillation column are: top pressure 0.05MPa~0.1MPa, top temperature 73~78℃, bottom temperature 76~85℃, and reflux ratio 3~5:1.

[0013] Furthermore, the organic acid component in the solid organic acid catalyst is at least one of alkyl / aryl substituted methanesulfonic acid derivatives, wherein the alkyl / aryl substituted methanesulfonic acid derivatives specifically include, but are not limited to, methanesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.

[0014] Furthermore, the solid organic acid catalyst is resin-encapsulated and molded into granules, which are then packed into porous mesh frames on each tray of the reaction section and arranged in layers along the height of the tower. Inert packing layers are spaced apart between adjacent catalyst layers to balance the gas-liquid distribution and prevent interference between catalyst bed layers. The inert packing layers can be inert random packing materials such as ceramic rings.

[0015] Furthermore, the light-removal tower is provided with a first feed inlet, which is preferably located on the side of the light-removal tower, for the entry of the crude low-carbon alcohol ester.

[0016] Furthermore, the light component removal tower is provided with a first top outlet, from which the light component impurities are distilled off.

[0017] Furthermore, the top outlet of the first column is connected to a condenser for condensing the light component impurities distilled out.

[0018] Furthermore, the light component impurities distilled from the top of the light component removal tower are condensed by a condenser and then enter a reflux tank. Part of the condensate is returned to the top of the light component removal tower as reflux liquid to control the separation effect of the tower; the other part of the condensate is removed from the system as light component impurity extract liquid and can be recycled or sent to the incineration unit for treatment.

[0019] Furthermore, the light component removal column is provided with a first column bottom outlet, and the extractive distillation column is provided with a second feed inlet. The first column bottom outlet is connected to the second feed inlet, which is used to send the column bottom liquid after the light component impurities have been removed to the extractive distillation column for subsequent processing.

[0020] Furthermore, the boiling point of the light component impurities separated by the light component removal tower is more than 20°C lower than that of the lower carbon alcohol esters.

[0021] Furthermore, the light component impurities include one or more of acetaldehyde, methyl acetate, ethyl formate, ethyl propionate, diethyl ether, diethyl ether, acetone, C5 alkanes (such as n-pentane, isopentane), C5 cycloalkanes (such as cyclopentane), or alkenes (such as 1-pentene, isoprene).

[0022] Furthermore, the bottom liquid of the light-removal column contains low-carbon alcohol esters, ethanol, and water.

[0023] Furthermore, the main component of the bottom liquid of the light-removal tower is low-carbon alcohol esters, and it contains ethanol and water to be removed, as well as possible small amounts of heavy components such as butanone and butyraldehyde.

[0024] Furthermore, the theoretical number of plates in the light-light removal tower is 20 to 50.

[0025] Furthermore, the extractant added to the extractive distillation column includes one or more of ethylene glycol, diethylene glycol, glycerol, or dimethyl sulfoxide, preferably an aqueous solution of ethylene glycol with a concentration of 20 wt.% to 40 wt.%. The function of the extractant is to change the relative volatility between ethanol, water, and lower carbon alcohol esters, making it easier for ethanol and water to be removed from the top of the column.

[0026] Furthermore, the extractive distillation column is provided with an extractant inlet at the top or middle for feeding the extractant.

[0027] Furthermore, the top of the extractive distillation column is provided with a second top outlet.

[0028] Furthermore, the discharge from the top outlet of the second column is ethanol-water binary azeotrope vapor and / or ethanol-water-lower carbon alcohol ester ternary azeotrope vapor.

[0029] Furthermore, the second column's top outlet is connected to a phase separator. The oil phase outlet of the phase separator is connected to the top reflux port of the extractive distillation column, and the water phase outlet is connected to a collection pipeline. The oil phase outlet discharges an oil phase rich in low-carbon alcohol esters and ethanol, while the water phase outlet discharges an aqueous phase rich in ethanol.

[0030] Furthermore, the outlet pipeline of the aqueous phase is connected to a recovery tower for the recovery or treatment of ethanol discharge.

[0031] Furthermore, the extractive distillation column is provided with a second reboiler outlet, and a third feed inlet is provided in the middle or upper part of the distillation column, with the second reboiler outlet connected to the third feed inlet.

[0032] Furthermore, the water content of the low-carbon alcohol esters treated by the extractive distillation column can be reduced to below 500 ppm.

[0033] Furthermore, the theoretical number of plates in the extractive distillation column is 30 to 45.

[0034] Furthermore, the distillation column is provided with a third top outlet for removing trace amounts of light components.

[0035] Furthermore, the light components removed by the distillation column have boiling points within 20°C lower than those of lower alcohol esters, including one or more of methanol, n-butyraldehyde, and isobutyraldehyde.

[0036] Furthermore, after being condensed, a portion of the gaseous light components distilled from the top outlet of the third column is refluxed back to the top of the distillation column to establish gas-liquid mass transfer and reduce the entrainment loss of low-carbon alcohols and esters; another portion of trace light components is removed from the system.

[0037] Furthermore, the distillation column is provided with a third reboiler outlet for discharging trace heavy components.

[0038] Furthermore, the boiling point of the heavy component is higher than that of the low-carbon alcohol ester, and the difference in boiling points is within 20°C. When ethyl acetate is the target product, the heavy component includes one or more of methyl propionate, isopropyl acetate, isopropanol, and butanone.

[0039] Furthermore, the distillation column is equipped with a side outlet for collecting high-purity low-carbon alcohol esters and conveying them to a dynamic melt crystallizer for further purification.

[0040] Furthermore, the low-carbon alcohol ester is extracted from the distillation column in either the gas or liquid phase.

[0041] Furthermore, the distillation column uses structured packing, specifically one of wire mesh corrugated structured packing or perforated metal plate corrugated structured packing.

[0042] Furthermore, the dynamic melt crystallizer is a vertical jacketed structure with a built-in scraper agitator for continuous or intermittent crystallization operations, and the cooling medium is an aqueous ethylene glycol solution. The top of the dynamic melt crystallizer has a fourth feed inlet, which connects to the side outlet of the distillation column; the bottom of the dynamic melt crystallizer has a fourth outlet, which connects to the downstream adsorption column assembly.

[0043] Furthermore, the adsorption tower group includes at least one primary adsorption tower and one secondary adsorption tower; The primary adsorption tower is filled with molecular sieves to remove moisture from the material to ≤10ppm; The secondary adsorption tower is filled with an adsorbent for selectively adsorbing metal ions and polar organic compounds.

[0044] Furthermore, the molecular sieve has a pore size of 3A or 4A.

[0045] Furthermore, the adsorbent is a chelating ion exchange resin or an adsorbent loaded with specific functional groups such as nitrogen, oxygen, and sulfur coordinating atoms.

[0046] Furthermore, the functional groups in the chelating ion exchange resin specifically include one or more of the following: iminooxalic acid group, aminophosphonic acid group, polyamine group, pyridineamine group, or thiol group.

[0047] Furthermore, the adsorbed metal ions include Na + K + Fe 3+ Ca 2+ or Cu 2+ One or more of the following: the polar organic compounds include alcohols containing hydroxyl groups (-OH), acids containing carboxyl groups (-COOH), aldehydes or ketones containing carbonyl groups (C=O), and ethers or acetals containing ether bonds (-O-).

[0048] Furthermore, the primary adsorption tower is provided with a fifth inlet and a fifth outlet; the secondary adsorption tower is provided with a sixth inlet and a sixth outlet.

[0049] Furthermore, the fifth feed port is connected to the fourth discharge port of the dynamic melting crystallizer, and the fifth discharge port is connected to the sixth feed port.

[0050] Furthermore, the reaction purification apparatus also includes a pervaporation membrane separation unit located downstream of and connected to the adsorption tower group, for selectively removing trace amounts of moisture and small molecule impurities.

[0051] Furthermore, the pervaporation membrane separation unit includes a membrane module for selectively removing moisture and small molecule impurities.

[0052] Furthermore, the membrane assembly comprises a polyvinyl alcohol / polysulfone composite membrane.

[0053] This invention provides a method for the reactive purification of electronic-grade low-carbon alcohol esters, which is implemented using the aforementioned purification apparatus and includes the following steps: S1. Reactive distillation column: Alcohol and acid raw materials are fed into the reactive distillation column and crude low-carbon alcohol esters are obtained by reactive distillation. S2, Light component removal: The crude low-carbon alcohol ester obtained in step S1 is passed into the light component removal tower to remove light component impurities therein; S3. Extractive distillation: The material obtained in step S2 is fed into the extractive distillation column, and an extractant is introduced into the extractive distillation column to remove ethanol and water that form azeotropes with low carbon alcohol esters through extractive distillation. S4. Precision distillation: The material obtained in step S3 is fed into the distillation column to separate impurities whose boiling points differ from those of low-carbon alcohol esters by less than 20°C. S5. Dynamic melt crystallization: The material obtained in step S4 is passed into a dynamic melt crystallizer. Taking advantage of the difference in freezing point (the freezing point of low carbon alcohol esters such as ethyl acetate is -83.6℃, ​​and the freezing point of other impurities is even lower), the low carbon alcohol esters are preferentially crystallized at -60℃ to -70℃, while the impurities remain in the liquid phase. After centrifugation, the crystals are heated and sweated to obtain an intermediate product with a purity ≥99.99%. S6. Deep adsorption: The material obtained in step S5 is passed into the adsorption tower group, and trace moisture, dissolved metal ions and polar organic matter are removed through at least two stages of adsorption process in series to obtain electronic grade low carbon alcohol ester product.

[0054] Furthermore, the operating conditions of the reactive distillation column are as follows: top pressure of 0.03 MPa to 0.15 MPa, top temperature of 65 to 79°C, bottom temperature of 75 to 95°C, and reflux ratio of 2 to 5:1.

[0055] Furthermore, the operating conditions of the reactive distillation column are: top pressure 0.05MPa~0.1MPa, top temperature 73~78℃, bottom temperature 76~85℃, and reflux ratio 3~5:1.

[0056] Furthermore, the absolute operating pressure at the top of the light-weight removal tower is 50 kPa to 101.3 kPa, the temperature at the top of the tower is 50 to 70°C, and the temperature at the bottom of the tower is 65 to 85°C.

[0057] Furthermore, the mass ratio of the extractant to the feed to the extractive distillation column is 0.3~1.5:1, preferably 0.5~1:1.

[0058] Furthermore, the absolute operating pressure of the extractive distillation column is 0.101 MPa to 0.3 MPa, the top temperature is 65 to 75°C, and the bottom temperature is 75 to 95°C.

[0059] Furthermore, the distillation column has at least 100 theoretical plates, a reflux ratio of 5 to 20:1, preferably 8 to 15:1, and an operating absolute pressure of 0.08 MPa to 0.101 MPa.

[0060] Furthermore, the operating conditions of the dynamic melt crystallizer are: crystallization temperature -60℃~-70℃, sweating temperature -40℃~-50℃. By utilizing the difference in freezing points between low-carbon alcohol esters and near-boiling impurities (such as methyl ethyl ketone, methyl propionate, etc.) (low-carbon alcohol esters such as ethyl acetate are at -83.6℃, ​​and other impurities are even lower), the content of impurities with a boiling point difference of <3℃ is further reduced to <0.01 ppm.

[0061] Furthermore, the operating conditions of the adsorption tower group are: operating at room temperature with a material space velocity of 1-3 h⁻¹. -1 .

[0062] Furthermore, the operating temperature of the pervaporation membrane separation unit is 50~60℃, and the operating pressure is 0.2~0.3MPa.

[0063] This invention also relates to the application of the above-mentioned reaction purification apparatus in the preparation of electronic-grade low-carbon alcohol esters.

[0064] Compared with the prior art, the present invention has the following advantages: This invention overcomes the limitations of conventional processes that cannot simultaneously remove azeotropics, near-boiling impurities, and trace contaminants through a fully continuous process involving reactive distillation, light ion removal, extractive distillation, high-theoretical-plate distillation, melt crystallization, and two-stage adsorption. It stably produces electronic-grade low-carbon alcohol esters that meet SEMI G4 / G5 standards for use in wet electronics. It also stably produces ultra-high purity low-carbon alcohol esters with a metal ion content ≤0.1ppb and a purity ≥99.995%, meeting the purity requirements of key wet processes such as photolithography and cleaning in current advanced semiconductor manufacturing and high-generation panel manufacturing.

[0065] (1) The ethyl acetate product obtained by this invention is upgraded from an industrial-grade product to meet the SEMI G4 / G5 standard. Through a six-stage continuous process of reactive distillation, light component removal, extractive distillation, high-theoretical-plate distillation, melt crystallization, and two-stage adsorption, a purity of ≥99.995%, moisture content ≤50 ppm, single metal ion content ≤0.1 ppb, and particulate matter content ≤5 / mL is stably obtained, fully meeting the electronic-grade low-carbon alcohol ester standards in the wet electronics field. Among them, the two-stage adsorption (molecular sieve + chelating resin) adopted in this scheme dehydrates the moisture content from ≤500 ppm to ≤10 ppm, reduces the metal ion content from ppb to ≤0.1 ppb, and reduces the polar organic matter content to <0.1 ppm. This is a purification process and effect that cannot be achieved by conventional adsorption.

[0066] (2) The core of the two-stage adsorption of this invention lies in functional decoupling and synergistic protection: the primary molecular sieve removes water from a depth of about 400 ppm to ≤10 ppm, avoiding residual water from causing resin hydrolysis or occupying active sites, thus ensuring the high selectivity of the secondary chelating resin; the secondary resin removes Na through chelating functional groups. + K + Fe 3+ When the metal ion concentration is reduced to ≤0.1 ppb (measured <0.01 ppb), polar organic compounds are simultaneously removed to <0.1 ppm via hydrogen bonding / dipole interactions. This is achieved at room temperature and a space velocity of 1–3 h⁻¹. -1 Running the system and avoiding side reactions is a crucial step in achieving the purity of SEMI G4 / G5.

[0067] (3) This invention preferably uses a high theoretical plate number (≥100 plates) distillation column and side stream sampling to achieve precise distillation separation of near-boiling impurities with a boiling point difference of <20℃. In contrast, the distillation column of patent CN112299999A has an actual plate number of only 48~60 plates and a reflux ratio of 1~4:1, which cannot separate impurities such as butanone (79.6℃) and methyl propionate (79.8℃) with a boiling point difference of <3℃ from ethyl acetate (77.1℃). The distillation column of this invention has a plate number ≥100 plates and a reflux ratio of 5~20:1, combined with side stream sampling; and the molten crystallization following the distillation separation, controlling the residual amount of the above-mentioned near-boiling impurities to <0.1 ppm. According to Fenske's formula N=lg(S) / lg( When the relative volatility α≈1.05, the initial 0.5% impurity is reduced to 0.1 ppm (separation factor S≈5×10). 4 The theoretical plate count needs to be ≥100. Therefore, the large reflux ratio and side-stream extraction in this scheme, combined with further melt crystallization, ensure that the separation is achieved.

[0068] (4) This invention eliminates batch-to-batch purity fluctuations caused by intermittent operations through continuous production, overcoming the problem of large-scale continuous production that is difficult in existing technologies. The six units of this invention are connected in series along the material flow direction to achieve continuous material flow, significantly improving production efficiency, and ensuring high long-term product stability and batch consistency, meeting the stringent requirements of semiconductor manufacturing.

[0069] (5) This invention can be integrated into the green reactive distillation front section to replace the traditional concentrated sulfuric acid catalysis. It achieves reaction separation coupling, reduces equipment corrosion and waste, and increases product purity from 99.95% to 99.996% compared to the traditional concentrated sulfuric acid catalysis process. The total metal ion content is reduced from 5~10 ppb to <0.05 ppb, which combines high purity with environmental protection and economy. Attached Figure Description

[0070] Figure 1 This is a process flow diagram of the reaction purification apparatus shown in Example 1.

[0071] Explanation of markings in the diagram: 1-Reactive distillation column; 2-Lightweight material removal tower, 21-First feed inlet, 22-First tower top outlet, 23-First tower bottom outlet; 3-Extractive distillation column, 31-Second feed inlet, 32-Extractant feed inlet, 33-Second column top outlet, 34-Second column bottom outlet; 4-Distillation column, 41-Third feed inlet, 42-Third column top outlet, 43-Third column bottom outlet, 44-Side stream outlet; 5-Dynamic melt crystallizer, 51-Fourth feed inlet, 52-Fourth discharge outlet; 6 - Adsorption tower group, 61 - Primary adsorption tower, 611 - Fifth feed inlet, 612 - Fifth discharge outlet, 62 - Secondary adsorption tower, 621 - Sixth feed inlet, 622 - Sixth discharge outlet; 7-Pervaporation membrane separation unit; 8-Phase separator, 81-Oil phase outlet, 82-Water phase outlet; 9-Recycling tower. Detailed Implementation

[0072] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. All other embodiments obtained by those skilled in the art based on the given embodiments without creative effort are within the scope of protection of this application.

[0073] Unless otherwise specified, the reagents, methods, instruments and equipment used in this invention are conventional reagents, methods, instruments and equipment in the art.

[0074] In the following examples, the ethanol, acetic acid, 3A molecular sieve (99% purity), iminodiacetic acid chelating ion exchange resin, and catalyst used in reactive distillation are all commercially available products.

[0075] A reactive purification apparatus for electronic-grade low-carbon alcohol esters, comprising, in sequence along the material flow direction: Reactive distillation column 1: Obtain crude low-carbon alcohol esters from alcohol and acid feedstocks through reactive distillation; Light component removal tower 2 is used to remove light component impurities (boiling point difference > 20°C) from crude low-carbon alcohol esters. Extractive distillation column 3 is used to remove ethanol and water that form azeotropes with low-carbon alcohol esters by extractive distillation; Distillation column 4 is used to separate impurities with boiling points close to those of low-carbon alcohol esters (boiling point difference < 20°C). The dynamic melt crystallizer 5 is used to further reduce near-boiling impurities with a boiling point difference of <3℃ to <0.01 ppm by utilizing the difference in freezing point; And an adsorption tower group 6, which consists of at least two adsorption towers connected in series, for removing trace amounts of moisture, dissolved metal ions and polar organic matter.

[0076] In some specific embodiments, the low-carbon alcohol ester is at least one of ethyl formate, methyl acetate, ethyl acetate, methyl propionate, or ethyl propionate.

[0077] In some specific embodiments, the ethyl acetate has a normal boiling point of about 77°C, the ethyl formate has a boiling point of about 54.7°C, the methyl acetate has a boiling point of about 58°C, the methyl propionate has a boiling point of about 79.8°C, and the ethyl propionate has a boiling point of about 99.1°C.

[0078] In some specific embodiments, the light-removal tower 2 is provided with a first feed inlet 21, which is preferably located on the side of the light-removal tower 2, for the entry of the crude low-carbon alcohol ester.

[0079] In some specific embodiments, the light component removal tower 2 is provided with a first top outlet 22, from which the light component impurities are distilled off from the top of the light component removal tower 2.

[0080] In some specific embodiments, the first column top outlet 22 is connected to a condenser for condensing and distilling out light component impurities with boiling points 20°C or higher than those of low carbon alcohol esters.

[0081] In some specific embodiments, the light component impurities distilled from the top of the light component removal tower 2 are condensed by a condenser and then enter a reflux tank. A portion of the condensate is returned to the top of the light component removal tower 2 as reflux liquid to control the separation effect of the tower; the other portion of the condensate is removed from the system as light component impurity extract liquid and can be recycled or sent to the incineration unit for treatment.

[0082] In some specific embodiments, the light component removal tower 2 is provided with a first tower bottom outlet 23, and the extractive distillation tower 3 is provided with a second feed inlet 31. The first tower bottom outlet 23 is connected to the second feed inlet 31, which is used to send the tower bottom liquid after the light component impurities are removed to the extractive distillation tower 3 for subsequent processing.

[0083] In some specific embodiments, the absolute pressure at the top of the light-weight removal tower 2 is 50 kPa to 101.3 kPa, the temperature at the top of the tower is 50 to 70°C, and the temperature at the bottom of the tower is 65 to 85°C.

[0084] In some specific embodiments, the light component impurities include one or more of acetaldehyde, methyl acetate, ethyl formate, ethyl propionate, diethyl ether, diethyl ether, acetone, C5 alkanes (such as n-pentane, isopentane), C5 cycloalkanes (such as cyclopentane), or alkenes (such as 1-pentene, isoprene).

[0085] In some specific embodiments, the bottom liquid of the light-removal tower 2 contains low-carbon alcohol esters, ethanol and water.

[0086] In some specific embodiments, the main component of the bottom liquid of the light removal tower 2 is low carbon alcohol ester, and it contains ethanol and water to be removed, as well as possible small amounts of heavy components such as butanone and butyraldehyde.

[0087] In some specific embodiments, the theoretical number of plates in the light-removal tower 2 is 20 to 50.

[0088] In some specific embodiments, the extractant added to the extractive distillation column 3 includes one or more of ethylene glycol, diethylene glycol, glycerol, or dimethyl sulfoxide, preferably an aqueous solution of ethylene glycol with a concentration of 20 wt.% to 40 wt.%. The function of the extractant is to change the relative volatility between ethanol, water, and lower carbon alcohol esters, making it easier for ethanol and water to be removed from the top of the column.

[0089] In some specific embodiments, the mass ratio of the extractant to the feed is 0.3~1.5:1, preferably 0.5~1:1.

[0090] In some specific embodiments, the operating absolute pressure of the extractive distillation column 3 is 0.101 MPa to 0.3 MPa, the top temperature is 65 to 75°C, and the bottom temperature is 75 to 95°C.

[0091] In some specific embodiments, the upper or middle part of the extractive distillation column 3 is provided with an extractant inlet 32 ​​for feeding the extractant.

[0092] In some specific embodiments, the top of the extractive distillation column 3 is provided with a second top outlet 33.

[0093] In some specific embodiments, the discharge from the second column top outlet 33 is ethanol-water binary azeotrope vapor and / or ethanol-water-lower carbon alcohol ester ternary azeotrope vapor.

[0094] In some specific embodiments, the second column top outlet 33 is connected to a phase separator 8. The oil phase outlet 81 of the phase separator 8 is connected to the top reflux port of the extractive distillation column 3, and the aqueous phase outlet 82 is connected to a collection pipeline. The oil phase outlet 81 discharges an oil phase rich in low-carbon alcohol esters and ethanol, and the aqueous phase outlet 82 discharges an aqueous phase rich in ethanol.

[0095] In some specific embodiments, the extraction pipeline of the aqueous phase outlet 82 is connected to the recovery tower 9 for the recovery or treatment of ethanol discharge.

[0096] In some specific embodiments, the extractive distillation column 3 is provided with a second reboiler outlet 34, and the distillation column 4 is provided with a third feed inlet 41 at the middle or upper part of the column, and the second reboiler outlet 34 is connected to the third feed inlet 41.

[0097] In some specific embodiments, the water content of the low-carbon alcohol esters after treatment by the extractive distillation column 3 can be reduced to below 500 ppm.

[0098] In some specific embodiments, the number of theoretical plates in the extractive distillation column 3 is 30 to 45.

[0099] In some specific embodiments, the distillation column 4 has at least 100 theoretical plates, i.e., ≥100 plates, a reflux ratio of 5~20:1, preferably 8~15:1, and an operating absolute pressure of 0.08 MPa~0.101 MPa.

[0100] In some specific embodiments, the distillation column 4 is provided with a third top outlet 42 for removing trace light components.

[0101] In some specific embodiments, the light components removed by distillation column 4 have boiling points within 20°C lower than those of lower carbon alcohol esters, including one or more of methanol, n-butyraldehyde, and isobutyraldehyde.

[0102] In some specific embodiments, after the light gaseous components distilled from the top outlet 42 of the third column are condensed, a portion is refluxed to the top of the distillation column 4 to establish gas-liquid mass transfer and reduce the entrainment loss of low-carbon alcohols and esters; another portion of trace light components is removed from the system.

[0103] In some specific embodiments, the distillation column 4 is provided with a third column bottom outlet 43 for discharging trace heavy components.

[0104] In some specific embodiments, the boiling point of the heavy component is within 20°C higher than that of the low carbon alcohol ester, and it includes one or more of methyl propionate, isopropyl acetate, isopropanol, and butanone.

[0105] In some specific embodiments, the distillation column 4 is provided with a side outlet 44 for collecting high-purity low-carbon alcohol esters and conveying them to the dynamic melt crystallizer 5.

[0106] In some specific embodiments, the low-carbon alcohol ester is collected from distillation column 4 in the gas or liquid phase.

[0107] In some specific embodiments, the distillation column 4 uses structured packing, which is one of metal wire mesh corrugated structured packing or metal perforated plate corrugated structured packing.

[0108] Furthermore, the dynamic melt crystallizer 5 is a vertical jacketed structure with a built-in scraper agitator for continuous or intermittent crystallization operations, and the cooling medium is an aqueous ethylene glycol solution. The top of the dynamic melt crystallizer 5 is provided with a fourth feed inlet 51, which connects to the side outlet 44 of the distillation column 4; the bottom of the dynamic melt crystallizer 5 is provided with a fourth outlet 52, which connects to the downstream adsorption column group 6.

[0109] Furthermore, the operating conditions of the dynamic melt crystallizer 5 are: crystallization temperature -60℃~-70℃, sweating temperature -40℃~-50℃. By utilizing the difference in freezing points between low-carbon alcohol esters and near-boiling impurities (such as methyl ethyl ketone, methyl propionate, etc.) (low-carbon alcohol esters such as ethyl acetate are at -83.6℃, ​​and other impurities are even lower), the content of impurities with a boiling point difference of <3℃ is further reduced to <0.01 ppm.

[0110] In some specific embodiments, the adsorption tower group 6 includes at least one primary adsorption tower 61 and one secondary adsorption tower 62; The primary adsorption tower 61 is filled with molecular sieves to remove moisture from the material to ≤10ppm. The secondary adsorption tower 62 is filled with an adsorbent for selectively adsorbing metal ions and polar organic compounds.

[0111] In some specific embodiments, the molecular sieve has a pore size of 3A or 4A.

[0112] In some specific embodiments, the adsorbent is a chelating ion exchange resin or an adsorbent loaded with specific functional groups such as nitrogen, oxygen, and sulfur coordinating atoms.

[0113] In some specific embodiments, the functional groups in the chelating ion exchange resin specifically include one or more of iminooxalic acid group, aminophosphonic acid group, polyamine group, pyridineamine group or mercapto group.

[0114] In some specific embodiments, the adsorbed metal ions include Na + K + Fe 3+ Ca 2+ or Cu 2+ One or more of the following: the polar organic compounds include alcohols containing hydroxyl groups (-OH), acids containing carboxyl groups (-COOH), aldehydes or ketones containing carbonyl groups (C=O), and ethers or acetals containing ether bonds (-O-).

[0115] In some specific embodiments, the operating conditions of the adsorption tower group 6 are: operating at room temperature with a material space velocity of 1~3 h⁻¹. -1 .

[0116] In some specific embodiments, the primary adsorption tower 61 is provided with a fifth inlet 611 and a fifth outlet 612; the secondary adsorption tower 62 is provided with a sixth inlet 621 and a sixth outlet 622.

[0117] In some specific embodiments, the fifth feed port 611 is connected to the fourth discharge port 52 of the dynamic melting crystallizer 5, and the fifth discharge port 612 is connected to the sixth feed port 621.

[0118] In some specific embodiments, the reaction purification apparatus further includes a pervaporation membrane separation unit 7 located downstream of and connected to the adsorption tower group 6, for selectively removing trace amounts of moisture and small molecule impurities.

[0119] In some specific embodiments, the pervaporation membrane separation unit 7 includes a membrane module for selectively removing moisture and small molecule impurities.

[0120] In some specific embodiments, the membrane assembly includes a polyvinyl alcohol / polysulfone composite membrane.

[0121] In some specific embodiments, the operating temperature of the pervaporation membrane separation unit 7 is 50~60℃ and the operating pressure is 0.2~0.3 MPa.

[0122] In some specific embodiments, to optimize the source of raw materials and the overall economic efficiency of the process, the reaction purification device is connected to the reaction distillation column 1 for synthesizing crude low-carbon alcohol esters, and the reaction distillation column 1 is located upstream of the light-removal column 2.

[0123] In some specific embodiments, the reactive distillation column 1 is filled with a solid organic acid catalyst.

[0124] In some specific embodiments, the organic acid component of the solid organic acid catalyst is at least one of methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, or other alkyl / aryl substituted methanesulfonic acid derivatives.

[0125] In some specific embodiments, the solid organic acid catalyst is resin-embedded and molded into granules, which are then packed into porous mesh frames on each tray of the reaction section and arranged in layers along the height of the tower. Inert packing layers are spaced apart between adjacent catalyst layers to balance the gas-liquid distribution and prevent mutual interference between catalyst beds. The inert packing layers can be inert random packing materials such as ceramic rings.

[0126] In some specific embodiments, the operating conditions of the reactive distillation column 1 are: top pressure of 0.03 MPa to 0.15 MPa, top temperature of 65 to 79°C, bottom temperature of 75 to 95°C, and reflux ratio of 2 to 5:1; more preferably, the operating conditions of the reactive distillation column 1 are: top pressure of 0.05 MPa to 0.1 MPa, top temperature of 76 to 78°C, bottom temperature of 78 to 85°C, and reflux ratio of 3 to 5:1.

[0127] In some specific embodiments, the top of the reactive distillation column 1 is provided with a condensation and phase separation device for condensing and separating the distillate into an organic phase and an aqueous phase, and the organic phase is transported to a reactive purification device.

[0128] A reaction purification method for electronic-grade low-carbon alcohol esters, implemented using the aforementioned apparatus, includes the following steps: S1. Reactive distillation: Alcohol and acid raw materials are fed into the reactive distillation column 1 and crude low-carbon alcohol esters are obtained by reactive distillation. S2, Light component removal: The crude low-carbon alcohol ester obtained in step S1 is passed into the light component removal tower 2 to remove light component impurities therein; S3, Extractive distillation: The material obtained in step S2 is fed into the extractive distillation column 3, and an extractant is introduced into the extractive distillation column 3 to remove ethanol and water that form azeotropes with low carbon alcohol esters through extractive distillation; S4. Precision distillation: The material obtained in step S3 is passed into the distillation column 4 to separate impurities with boiling points close to those of low-carbon alcohol esters. S5. Dynamic melting crystallization: The material obtained in step S4 is fed into the dynamic melting crystallizer 5, and the near-boiling impurities with a boiling point difference of <3℃ are further reduced to <0.01 ppm by utilizing the difference in freezing point. S6. Deep adsorption: The material obtained in step S5 is passed into the adsorption tower group 6. Through at least two stages of adsorption process in series, trace moisture, dissolved metal ions and polar organic matter are removed to obtain electronic grade low carbon alcohol ester product.

[0129] Application of a reaction purification apparatus for electronic-grade low-carbon alcohol esters in the preparation of electronic-grade low-carbon alcohol esters.

[0130] Each embodiment described in this scheme can be implemented individually or in any combination of two or more.

[0131] The following description uses specific examples to illustrate the point.

[0132] Example 1 A reactive purification apparatus for electronic-grade ethyl acetate, comprising, in sequence along the material flow direction: Reactive distillation column 1: Obtain crude low-carbon alcohol esters from alcohol and acid feedstocks through reactive distillation; Light component removal tower 2 is used to remove light component impurities from crude ethyl acetate. Extractive distillation column 3 is used to remove ethanol and water, which form an azeotrope with the ethyl acetate, by extractive distillation. Distillation column 4 is used to separate impurities with boiling points close to those of ethyl acetate; The dynamic melt crystallizer 5 is used to further reduce near-boiling impurities with a boiling point difference of <3℃ to <0.01 ppm by utilizing the difference in freezing point; And an adsorption tower group 6, which consists of at least two adsorption towers connected in series, for removing trace amounts of moisture, dissolved metal ions and polar organic matter.

[0133] In this embodiment, the upper part of the reactive distillation column 1 is provided with an acid (heavy component) inlet and the middle part is provided with an alcohol (light component) inlet. The acid and alcohol materials are in countercurrent contact with the loaded solid organic acid catalyst in the reaction section of the reactive distillation column 1, and generate crude low-carbon alcohol ester through esterification reaction. After the distillate from the top of the column is condensed and separated by the phase separator 8, the upper organic phase is sent to the light component removal column 2 as crude ester, and the lower aqueous phase is discharged or recovered.

[0134] In this embodiment, the operating conditions of the reactive distillation column 1 are: top pressure 0.03 MPa~0.15 MPa, top temperature 65~79℃, bottom temperature 75~95℃, and reflux ratio 2~5:1; more preferably, the operating conditions of the reactive distillation column 1 are: top pressure 0.05 MPa~0.1 MPa, top temperature 76~78℃, bottom temperature 78~85℃, and reflux ratio 3~5:1.

[0135] In this embodiment, the organic acid component in the solid organic acid catalyst is at least one of alkyl / aryl substituted methanesulfonic acid derivatives.

[0136] In this embodiment, the light-removal tower 2 is provided with a first feed inlet 21, which is located on the side of the light-removal tower 2 for the entry of the crude ethyl acetate.

[0137] In this embodiment, the light component removal tower 2 is provided with a first top outlet 22, and the light component impurities are distilled out from the top of the light component removal tower 2.

[0138] In this embodiment, the first column top outlet 22 is connected to a condenser for condensing and removing light component impurities distilled from the light column 2.

[0139] In this embodiment, the light component impurities distilled from the top of the light component removal tower 2 are condensed by the condenser and then enter the reflux tank. Part of the condensate is returned to the top of the light component removal tower 2 as reflux liquid to control the separation effect of the tower; the other part of the condensate is removed from the system as light component impurity extract liquid and can be recycled or sent to the incineration unit for treatment.

[0140] In this embodiment, the light component removal tower 2 is provided with a first tower bottom outlet 23, and the extractive distillation tower 3 is provided with a second feed inlet 31. The first tower bottom outlet 23 is connected to the second feed inlet 31, and is used to send the tower bottom liquid after the removal of light component impurities to the extractive distillation tower 3 for subsequent processing.

[0141] In this embodiment, the theoretical number of trays in the light-light removal tower 2 is 30.

[0142] In this embodiment, the upper or middle part of the extractive distillation column 3 is provided with an extractant inlet 32 ​​for feeding the extractant.

[0143] In this embodiment, the top of the extractive distillation column 3 is provided with a second top outlet 33.

[0144] In this embodiment, the second column top outlet 33 is connected to a phase separator 8. The oil phase outlet 81 of the phase separator 8 is connected to the top reflux port of the extractive distillation column 3, and the aqueous phase outlet 82 is connected to a collection pipeline. The oil phase outlet 81 discharges an oil phase rich in ethyl acetate and ethanol, and the aqueous phase outlet 82 discharges an aqueous phase rich in ethanol.

[0145] In this embodiment, the extraction pipeline of the aqueous phase outlet 82 is connected to the recovery tower 9 for the recovery or treatment and discharge of ethanol.

[0146] In this embodiment, the extractive distillation column 3 is provided with a second reboiler outlet 34, and the distillation column 4 is provided with a third feed inlet 41 at the middle position. The second reboiler outlet 34 is connected to the third feed inlet 41.

[0147] In this embodiment, the extractive distillation column 3 has a theoretical number of 40 trays, the extractant inlet 32 ​​is located at the 25th tray, and the second reboiler outlet 34 is located at the 10th tray on the column side line.

[0148] In this embodiment, the distillation column 4 uses a metal wire mesh corrugated structured packing with a plate height of approximately 0.3 m and a total height equivalent to 120 theoretical plates.

[0149] In this embodiment, the distillation column 4 is provided with a third top outlet 42 for removing trace light components.

[0150] In this embodiment, a portion is refluxed to the top of distillation column 4 to establish gas-liquid mass transfer and reduce ethyl acetate entrainment loss; another portion of trace light components is removed from the system.

[0151] In this embodiment, the distillation column 4 is provided with a third column bottom outlet 43 for discharging trace heavy components.

[0152] In this embodiment, the distillation column 4 is provided with a side stream outlet 44 for collecting high-purity ethyl acetate, and the side stream outlet 44 is located at the 60th theoretical plate.

[0153] In this embodiment, the dynamic melt crystallizer 5 is located downstream of the distillation column 4 and upstream of the adsorption column group 6. It has a vertical jacket structure and a built-in scraper stirring device to realize continuous or intermittent crystallization operation. The cooling medium is an aqueous solution of ethylene glycol.

[0154] In this embodiment, the operating conditions of the dynamic melt crystallizer 5 are: crystallization temperature -60℃ to -70℃, sweating temperature -40℃ to -50℃. By utilizing the difference in freezing points between ethyl acetate and near-boiling impurities (such as butanone and methyl propionate) (ethyl acetate -83.6℃, ​​impurities are even lower), the content of impurities with a boiling point difference of <3℃ is further reduced to <0.01 ppm.

[0155] In this embodiment, the adsorption tower group 6 includes a primary adsorption tower 61 and a secondary adsorption tower 62; The primary adsorption tower 61 is filled with molecular sieves to remove moisture from the material to ≤10ppm. The secondary adsorption tower 62 is filled with an adsorbent for selectively adsorbing metal ions and polar organic compounds.

[0156] In this embodiment, the pore size of the molecular sieve is 3 Å.

[0157] In this embodiment, the adsorbent is an iminooxic acid-type chelating ion exchange resin.

[0158] In this embodiment, both the primary adsorption tower 61 and the secondary adsorption tower 62 are adsorption columns, wherein the molecular sieve packed in the primary adsorption tower 61 is 2m. 3 The adsorbent packed in the secondary adsorption tower 62 is 1m³. 3 .

[0159] In this embodiment, the primary adsorption tower 61 is provided with a fifth inlet 611 and a fifth outlet 612; the secondary adsorption tower 62 is provided with a sixth inlet 621 and a sixth outlet 622.

[0160] In this embodiment, the fifth feed port 611 is connected to the fourth discharge port 52 at the bottom of the dynamic melting crystallizer 5, and the fifth discharge port 612 is connected to the sixth feed port 621.

[0161] A reactive purification method for electronic-grade low-carbon alcohol esters (with ethyl acetate as the target product), implemented using the aforementioned purification apparatus, includes the following steps. The crude ethyl acetate is industrial-grade ethyl acetate, obtained by reactive distillation of low-carbon alcohols and acids in reactive distillation column 1, with a purity of approximately 92%. The main impurities are water (~3%), ethanol (~3%), butanone (~0.5%), trace amounts of acetic acid, and sodium. + K + Fe 3+ Ca 2+ or Cu 2+ Metal ions, etc.

[0162] S1, Reactive Distillation Column 1: Alcohol and acid feedstocks are subjected to reactive distillation to obtain crude low-carbon alcohol esters. Acetic acid is continuously fed into reactive distillation column 1 at a rate of 320 kg / h and ethanol at a rate of 280 kg / h. The acid and alcohol react countercurrently with a solid organic acid catalyst in the reaction section, undergoing esterification to produce crude ethyl acetate. After condensation and phase separation, the upper organic phase is sent as crude ester to light-weight phase removal column 2, while the lower aqueous phase is discharged or recovered. The operating conditions of reactive distillation column 1 are as follows: top pressure controlled at 0.05–0.1 MPa (absolute pressure), top temperature controlled at 73–78°C, bottom temperature controlled at 76–85°C, and reflux ratio controlled at 3–5:1.

[0163] S2, Lightening: Crude ethyl acetate is fed into the light-light product removal tower 2 at a flow rate of 500 kg / h through the first feed inlet 21. The absolute operating pressure at the top of the light-light product removal tower 2 is 50 kPa (corresponding to gauge pressure -0.05 MPa), the top temperature is 65℃, and the bottom temperature is 78℃.

[0164] In this embodiment, light component impurities are distilled off from the top outlet 22 of the first column, removing approximately 2% of the light component impurities from the top of the column. The light component impurities distilled off the top of the light component removal column 2 are condensed in a condenser and then enter a reflux tank. A portion of the condensate is returned to the top of the light component removal column 2 as reflux liquid to control the separation effect of the column; this portion of condensate accounts for 91% and can be precisely controlled by adjusting the reflux ratio. The other portion of the condensate is removed from the system as light component impurity product and can be recycled or sent to the incineration unit for treatment. The boiling point of the light component impurity is more than 20°C lower than that of ethyl acetate. The light component impurity includes one or more of the following: methyl acetate (boiling point 56.7~57.8°C), diethyl ether (boiling point 34.5~34.6°C), n-pentane (boiling point 36.1°C), isopentane (boiling point 27.8~27.9°C), cyclopentane (boiling point 49.2~49.3°C), 1-pentene (boiling point 30°C), and isoprene (boiling point 34.0~34.1°C).

[0165] In this embodiment, the bottom liquid of the light-removal tower 2 flows out from the first bottom outlet 23 at a flow rate of 550 kg / h. The main component of the bottom liquid is ethyl acetate, and it also contains ethanol and water to be removed, as well as a small amount of heavy components such as butanone and butyraldehyde, which may be present. The liquid is detected by gas chromatography-mass spectrometry (GC-MS).

[0166] S3, Extractive distillation: The liquid from the bottom of the first column (outlet 23) flows into the extractive distillation column 3 through the second inlet 31, where ethanol and water, which form an azeotrope with ethyl acetate, are removed by extractive distillation. A 30 wt.% aqueous ethylene glycol solution is injected as the extractant through the extractant inlet 32 ​​at a flow rate of 250 kg / h (extractant / feed mass ratio ≈ 0.55:1). The extractive distillation column 3 operates at atmospheric pressure, with a top temperature of 70.5°C and a bottom temperature of 85°C.

[0167] In this embodiment, ethanol-water binary azeotrope vapor and ethanol-water-ethyl acetate ternary azeotrope vapor flow out from the top outlet 33 of the second column. The vapor enters the phase separator 8, and after passing through the phase separator 8, it comprises an oil phase and an aqueous phase. The oil phase is rich in ethyl acetate and ethanol; the aqueous phase is rich in ethanol. The oil phase flows back to the top of the extractive distillation column 3 from the oil phase outlet 81; the aqueous phase flows out from the aqueous phase outlet 82 and flows into the recovery column 9 through the collection pipeline for ethanol recovery.

[0168] In this embodiment, dehydrated ethyl acetate was collected from the liquid phase at outlet 34 of the second tower, with a flow rate of approximately 455 kg / h and a water content analysis of 400 ppm.

[0169] S4, Precision Distillation: Dehydrated ethyl acetate collected from the liquid phase at the outlet 34 of the second column enters the distillation column 4 through the third inlet 41 to separate impurities with boiling points close to that of ethyl acetate. The operating pressure is atmospheric pressure, and the reflux ratio is 15:1.

[0170] In this embodiment, a trace amount of light components is discharged from the top outlet 42 of the third tower. The boiling point of the light components is less than 20°C below that of ethyl acetate, including one or more of methanol (boiling point 64.7°C), n-butyraldehyde (boiling point 75.7°C), and isobutyraldehyde (boiling point 64.5°C).

[0171] In this embodiment, a trace amount of heavy components is discharged from the outlet 43 of the third tower. The boiling point of the heavy components is within 20°C higher than that of ethyl acetate, and includes one or more of methyl propionate (boiling point 79.8°C), isopropyl acetate (boiling point 88.8~89.0°C), isopropanol (boiling point 82.5°C), and butanone (boiling point 79.6°C).

[0172] In this embodiment, high-purity ethyl acetate product is collected from the side outlet 44 at a flow rate of approximately 450 kg / h.

[0173] S5. Dynamic melt crystallization: The high-purity ethyl acetate product collected from the side outlet 44 is sent to the dynamic melt crystallizer 5. The crystallization temperature is controlled at -60℃ to -70℃ to allow ethyl acetate to crystallize preferentially, while impurities such as butanone and methyl propionate are enriched in the liquid phase. After centrifugation, the crystals are heated and sweated to further remove surface impurities, resulting in an intermediate product with a purity of ≥99.99%.

[0174] S6, Deep Adsorption: High-purity ethyl acetate product is collected from the fourth outlet 52 at the bottom of the dynamic melt crystallizer 5 and flows into the first-stage adsorption tower 61 through the fifth inlet 611, exits from the fifth outlet 612, then flows into the second-stage adsorption tower 62 through the sixth inlet 621, and finally exits through the sixth outlet 622. Through the two-stage adsorption process, trace amounts of water, dissolved metal ions, and polar organic matter are removed to obtain a refined and purified ethyl acetate product.

[0175] In this embodiment, the operating conditions of the adsorption tower group 6 are: operating at room temperature with a material space velocity of 2 h⁻¹. -1 .

[0176] In this embodiment, the adsorbed metal ions include Na + K + Fe 3+ Ca 2+ and Cu 2+ The polar organic compounds are confirmed by gas chromatography or liquid chromatography to include one or more of the following: alcohols (such as ethanol, methanol, and isopropanol) and acids (such as acetic acid) containing hydroxyl groups (-OH); aldehydes (such as acetaldehyde, n-butyraldehyde, and isobutyraldehyde) and ketones (such as butanone) containing carbonyl groups (C=O); and ethers (such as diethyl ether and diethyl ether) and acetals (such as acetaldehyde diethanol).

[0177] Example 2 This embodiment is based on embodiment 1.

[0178] In this embodiment, the reaction purification device further includes a pervaporation membrane separation unit 7 located downstream of and connected to the adsorption tower group 6, for selectively removing trace amounts of moisture and small molecule impurities.

[0179] In this embodiment, the pervaporation membrane separation unit 7 includes a membrane module for selectively removing moisture and small molecule impurities. The membrane module is either a polyvinyl alcohol or a polysulfone composite membrane.

[0180] In this embodiment, the purification method further includes a pervaporation step: S7, Pervaporation Separation: The ethyl acetate product flowing out from the sixth outlet 622 is passed through the pervaporation membrane separation unit 7 to selectively remove trace amounts of water and small molecule impurities, resulting in the final purified ethyl acetate product.

[0181] In this embodiment, the operating temperature of the pervaporation membrane separation unit 7 is 55°C and the operating pressure is 0.25 MPa.

[0182] The final purified ethyl acetate product was analyzed using international standard detection methods including gas chromatography-FID (GC-FID), Karl Fischer coulometric method, inductively coupled plasma mass spectrometry (ICP-MS), and particle counting. Compared with Example 1 (after two-stage adsorption), the addition of a pervaporation membrane unit further improved the product purity from 99.992% to over 99.995%, reduced water content from 5 ppm to 2-3 ppm, reduced metal ion content from <0.01 ppb to ≤0.005 ppb, and reduced particulate matter from 1 particle / mL to undetectable (<1 particle / mL). This membrane unit can remove trace amounts of water, dissolved ions, and submicron-sized particles that are difficult to remove by the adsorption unit, overcoming the three major technical challenges in the existing purification process of crude low-carbon alcohol esters: azeotropic dehydration, near-boiling impurity separation, and deep removal of trace contaminants. The test results show that the final purified product meets the SEMI G4 / G5 standards.

[0183] Example 3 This embodiment is based on Example 2. In order to optimize the source of raw materials and the overall process economy, the solid organic acid catalyst loaded in the reactive distillation column 1 used to synthesize crude ethyl acetate is optimized and limited as follows.

[0184] In this embodiment, the reactive distillation column 1 is filled with a fixed organic acid catalyst. The organic acid component is at least one of methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, or other alkyl / aryl substituted methanesulfonic acid derivatives. The catalyst is resin-embedded, and its active organic acid component (such as sulfonic acid groups) exhibits high acid density and excellent catalytic activity under reaction conditions, significantly accelerating the esterification reaction rate. Furthermore, the catalyst is insoluble in the reaction system and can be recycled for a long time, avoiding the corrosion of equipment and contamination of product purity caused by traditional liquid acid catalyst treatment processes.

[0185] In this embodiment, the solid organic acid catalyst is resin-encapsulated and molded into granules, which are then packed into porous mesh frames on each tray of the reaction section and arranged in layers along the height of the tower. Inert packing layers are spaced apart between adjacent catalyst layers to balance the gas-liquid distribution and prevent interference between catalyst bed layers. The inert packing layers can be inert random packing materials such as ceramic rings.

[0186] In this embodiment, the synthesis process of the crude ethyl acetate is as follows: using glacial acetic acid (99.8%) and ethanol (99.5%) as raw materials, a catalytic esterification reaction is carried out in a reactive distillation column 1 in the presence of a solid organic acid catalyst, while the products are separated at the same time; the distillate from the top of the column is condensed and separated into phases, and the resulting organic phase is passed into a reactive purification device for purification.

[0187] In this embodiment, the operating conditions of the reactive distillation column 1 are: top pressure 0.08 MPa, top temperature 74°C, bottom temperature 82°C, and reflux ratio 4:1.

[0188] The ethyl acetate produced by this process has a purity of up to 99.996%, a moisture content of only 8 ppm, and a total metal ion content of less than 0.05 ppb, which is superior to electronic grade standards (purity ≥99.99%, moisture content ≤100 ppm) and meets the requirements for semiconductor-grade ultrapure solvents. Furthermore, the entire process does not require the use of concentrated sulfuric acid, and the catalyst can be regenerated multiple times. Therefore, this process combines the advantages of high product purity and low pollution emissions, as shown in Table 1.

[0189] Table 1: Measurement results of each process component in Example 3 Comparative Example 1 The same raw material was processed using a low-theoretical-plate distillation column (50 plates, reflux ratio 3:1, other details the same as in Example 1). Due to insufficient theoretical plates (≥100 plates in this scheme, 120 plates in Example 1), near-boiling impurities with a boiling point difference <3℃ could not be fully separated. Specifically, when ethyl acetate was the target product, the side stream contained approximately 200 ppm of methyl ethyl ketone and approximately 150 ppm of methyl propionate, exceeding the melting and crystallization removal load; the final product had a purity of 99.98%, water content of 2 ppm, and metal ions ≤0.005 ppb, but methyl ethyl ketone residue of approximately 80 ppm and methyl propionate residue of approximately 60 ppm, with total organic impurities exceeding 140 ppm. Furthermore, when methyl propionate was used as the target product, the key near-boiling impurities became butanone (79.6℃) and ethyl acetate (77.1℃). Since the boiling point difference between butanone and methyl propionate is only 0.2℃, the separation is more stringent. The side stream contained approximately 250 ppm of butanone and approximately 120 ppm of ethyl acetate. The final product had a purity of approximately 99.97%, with 2 ppm of water and ≤0.005 ppb of metal ions. However, there were approximately 120 ppm of residual butanone and approximately 50 ppm of residual ethyl acetate, and the total organic impurities exceeded 170 ppm.

[0190] Comparative Example 2 The same raw material was processed without the dynamic melt crystallizer (the rest is the same as in Example 2). Due to the lack of melt crystallization, near-boiling impurities (boiling point difference <3℃) such as methyl ethyl ketone (79.6℃) and methyl propionate (79.8℃) in the distillation side stream could not be effectively removed. Specifically, when ethyl acetate was used as the target product, the final product had a purity of 99.97%, a moisture content of 5 ppm, metal ions <0.01 ppb, butanone residue of approximately 50 ppm, methyl propionate residue of approximately 30 ppm, and total organic impurities exceeding 100 ppm. Furthermore, when methyl propionate was used as the target product, the key near-boiling impurities became butanone (79.6℃) and ethyl acetate (77.1℃). The boiling point difference between butanone and methyl propionate was only 0.2℃, making the separation process more stringent than with the ethyl acetate system. The final product had a purity of approximately 99.96%, a moisture content of 5 ppm, metal ions <0.01 ppb, butanone residue of approximately 70 ppm, ethyl acetate residue of approximately 40 ppm, and total organic impurities exceeding 110 ppm.

[0191] Therefore, it can be seen that without dynamic melt crystallization, neither of the two target products met the SEMI G4 / G5 standard (purity ≥99.995%, total impurities ≤50 ppm).

[0192] Comparative Example 3 The same raw material was processed using a process that omitted the pervaporation membrane unit (the rest is the same as in Example 3). Because this membrane separation unit was missing as the final purification step, the approximately 5 ppm moisture and submicron particles remaining after the two-stage adsorption could not be further removed. This is because: adsorption is an equilibrium separation process; the molecular sieve reaches near adsorption equilibrium after removing approximately 5 ppm of moisture and cannot further reduce the residual moisture; simultaneously, fixed-bed adsorption has almost no retention capacity for suspended submicron solid particles. In contrast, pervaporation membrane separation is a mass transfer process driven by the vapor pressure difference across the membrane, and is not limited by adsorption equilibrium, enabling the removal of moisture from 5 ppm to 2-3 ppm; furthermore, the dense membrane layer has a certain physical sieving effect, which can retain submicron particles. Specifically, when ethyl acetate is used as the target product, without this membrane unit, the final product purity is 99.992% (total impurities approximately 80 ppm). Although the water content can reach 5 ppm (meeting the ≤50 ppm requirement), the particulate matter content is approximately 1-2 particles / mL, which fails to meet the near-zero detection requirement for particulate matter in the SEMI G4 / G5 standard (usually requiring <1 particle / mL), and the total impurities also exceed 50 ppm. Furthermore, when methyl propionate is used as the target product, the residual water content is approximately 5 ppm, but the particulate matter content is approximately 1-2 particles / mL, and the purity is approximately 99.991%. Both the particulate matter and purity indicators also fail to meet the SEMI G4 / G5 standard.

[0193] Therefore, without a pervaporation membrane separation unit, neither of the two target products can achieve further removal of water and complete removal of particulate matter due to the lack of a final membrane purification step.

[0194] The results of the determination of esters and impurities in the examples and comparative examples are shown in Table 2.

[0195] Table 2: Results of determination of purity and total impurity content of low-carbon alcohol esters in each example and comparative example This invention achieves the step-by-step cutting and systematic removal of impurities through a fully continuous process chain including reactive distillation, light component removal, extractive distillation, high-theoretical-plate distillation, melt crystallization, two-stage adsorption, and pervaporation: First, low-carbon alcohols and acids are distilled into crude esters via a reactive distillation column. Then, a light component removal column removes light component impurities with a boiling point difference >20℃, reducing the burden on the subsequent extractive distillation column for breaking down the azeotropic system. The extractive distillation column breaks down the azeotrope, reducing the water content to below 500 ppm, ensuring a stable feed for the distillation column. A high-theoretical-plate distillation column (≥100 plates), combined with a large reflux ratio and side-stream sampling, controls the residual amount of near-boiling impurities with a boiling point difference <20℃ to a low level, providing a high-purity feed for melt crystallization. Melt crystallization further utilizes the difference in freezing points to reduce impurities with a boiling point difference <3℃, which are difficult to separate by distillation, to <0.01%. The purity was increased to 99.99% by ppm. Two-stage adsorption (molecular sieve and chelating resin) removed trace amounts of water, metal ions, and polar organic matter. The first-stage molecular sieve removed water from 400 ppm to ≤10 ppm, effectively protecting the adsorption activity of the second-stage chelating resin, which reduced metal ions to <0.01 ppb and polar organic matter to <0.1 ppm. The adsorption capacity was increased by about 40% compared to no dehydration protection. The pervaporation membrane unit, as the final purification step, reduced residual water from 5 ppm to 2~3 ppm, metal ions to ≤0.005 ppb, and particulate matter from ≤2 particles / mL to undetectable. The six process units are functionally decoupled and progressively advanced: reactive distillation of alcohol and acid raw materials to synthesize crude low-carbon alcohol esters; removal of light components and extractive distillation to solve azeotropic dehydration; distillation and melt crystallization to break through the near-boiling impurity separation limit; and adsorption and pervaporation to overcome the bottleneck of trace pollutant removal. Together, they achieve the SEMI G4 / G5 standard of product purity ≥99.995%, metal ion ≤0.1 ppb, and no particulate matter detected.

[0196] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A reaction purification apparatus for electronic-grade low-carbon alcohol esters, characterized in that, The reaction purification apparatus, along the material flow direction, comprises: The reactive distillation column (1) is used to obtain crude low-carbon alcohol esters from low-carbon alcohol and acid raw materials by reactive distillation; the low-carbon alcohol esters in the crude low-carbon alcohol esters are at least one of ethyl formate, methyl acetate, ethyl acetate, methyl propionate and ethyl propionate. Light component removal tower (2) is used to remove light component impurities in crude low carbon alcohol esters that have a boiling point difference of more than 20°C from the low carbon alcohol esters. Extractive distillation column (3) is used to remove ethanol and water that form azeotropes with low carbon alcohol esters by extractive distillation; The distillation column (4) has at least 100 theoretical plates and uses a side-stream sampling method to separate impurities whose boiling points differ from those of low-carbon alcohol esters by less than 20°C. Impurities whose boiling points differ from those of low-carbon alcohol esters by less than 20°C include one or more of methanol, n-butyraldehyde, isobutyraldehyde, isopropyl acetate, isopropanol, and butanone. When the target low-carbon alcohol ester is not methyl propionate, impurities whose boiling points differ from those of low-carbon alcohol esters by less than 20°C also include methyl propionate. Dynamic melt crystallizer (5) is used to separate low carbon alcohol esters from impurities with a boiling point difference of less than 3°C by utilizing the difference in freezing point; And an adsorption tower assembly (6), which consists of at least two adsorption towers connected in series, for removing trace amounts of moisture, dissolved metal ions, and polar organic matter; the metal ions include Na+. + K + Fe 3+ Ca 2+ and Cu 2+ One or more of the following; polar organic compounds include one or more of the following: alcohols containing hydroxyl groups, acids containing carboxyl groups, aldehydes or ketones containing carbonyl groups, and ethers or acetals containing ether bonds.

2. The reaction purification apparatus for electronic-grade low-carbon alcohol esters according to claim 1, characterized in that, Includes one or more of the following: i) The reactive distillation column (1) is filled with a solid organic acid catalyst, wherein the organic acid component of the catalyst is at least one of alkyl / aryl substituted methanesulfonic acid derivatives; ii) The extractant added to the extractive distillation column (3) includes one or more of ethylene glycol, diethylene glycol, glycerol or dimethyl sulfoxide.

3. The reaction purification apparatus for electronic-grade low-carbon alcohol esters according to claim 1, characterized in that, The adsorption tower group (6) includes at least one primary adsorption tower (61) and one secondary adsorption tower (62). The primary adsorption tower (61) is filled with molecular sieves to remove moisture from the material to ≤10ppm; The secondary adsorption tower (62) is filled with an adsorbent for selectively adsorbing metal ions and polar organic compounds.

4. The reaction purification apparatus for electronic-grade low-carbon alcohol esters according to claim 1, characterized in that, The reaction purification apparatus also includes a pervaporation membrane separation unit (7) located downstream of and connected to the adsorption tower group (6).

5. A method for the reactive purification of electronic-grade low-carbon alcohol esters, wherein the method is implemented using the reactive purification apparatus described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Reactive distillation: The alcohol and acid raw materials are fed into the reactive distillation column (1) and crude low-carbon alcohol esters are obtained by reactive distillation. S2, Light component removal: The crude low-carbon alcohol ester obtained in step S1 is passed into the light component removal tower (2) to remove light component impurities therein; S3, Extractive distillation: The material obtained in step S2 is fed into the extractive distillation column (3), and an extractant is introduced into the extractive distillation column (3) to remove ethanol and water that form azeotropes with low carbon alcohol esters through extractive distillation; S4. Precision distillation: The material obtained in step S3 is fed into the distillation column (4) to separate impurities whose boiling points differ from those of low carbon alcohol esters by less than 20°C. S5. Dynamic melting crystallization: The material obtained in step S4 is fed into a dynamic melting crystallizer (5). The low carbon alcohol ester is preferentially crystallized at -60℃ to -70℃ by taking advantage of the difference in freezing point. Impurities remain in the liquid phase. After centrifugation, the crystals are heated and sweated to obtain intermediate product material with a purity ≥99.99%. S6. Deep adsorption: The material obtained in step S5 is passed into the adsorption tower group (6) and removed through at least two stages of adsorption process to remove trace moisture, dissolved metal ions and polar organic matter, and obtain electronic grade low carbon alcohol ester product.

6. The method for reactive purification of electronic-grade low-carbon alcohol esters according to claim 5, characterized in that, The reactive distillation column (1) has a top pressure of 0.03 MPa to 0.15 MPa, a top temperature of 65 to 79°C, a bottom temperature of 75 to 95°C, and a reflux ratio of 2 to 5:

1.

7. The method for reactive purification of electronic-grade low-carbon alcohol esters according to claim 5, characterized in that, The absolute pressure at the top of the light-removal tower (2) is 50 kPa to 101.3 kPa, the temperature at the top of the tower is 50 to 70°C, and the temperature at the bottom of the tower is 65 to 85°C.

8. The method for reactive purification of electronic-grade low-carbon alcohol esters according to claim 5, characterized in that, The absolute operating pressure of the extractive distillation column (3) is 0.101 MPa~0.3 MPa, the top temperature is 65~75℃, and the bottom temperature is 75~95℃. The mass ratio of the added extractant to the feed of the extractive distillation column (3) is 0.3~1.5:

1.

9. The method for reactive purification of electronic-grade low-carbon alcohol esters according to claim 5, characterized in that, The distillation column (4) has at least 100 theoretical plates, a reflux ratio of 5 to 20:1, and an operating absolute pressure of 0.08 MPa to 0.101 MPa.

10. The application of the reaction purification apparatus according to any one of claims 1 to 4 in the preparation of electronic-grade low-carbon alcohol esters.

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