Preparation method of electronic grade trifluoroacetic acid and silicon carbide regular packing rectification device

Abstract

The application is suitable for the technical field of chemical material preparation, and provides a preparation method of electronic-grade trifluoroacetic acid, which comprises the following steps: S1, raw material preheating and feeding; S2, gas-liquid mass transfer and separation; the material is subjected to gas-liquid countercurrent contact mass transfer in a rectifying tower; S3, multistage extraction and product collection; the S1 comprises: S1-1, raw material preheating: industrial-grade trifluoroacetic acid raw material with a purity of 98% to 99% is heated to the bubble point temperature through a preheater made of graphite or silicon carbide, and the temperature range is 40 to 60 DEG C; S1-2, feeding: the material enters the rectifying tower through a feeding distributor, and the feeding position is arranged at 1 / 3 to 1 / 2 of the tower body from bottom to top, so that enough rectifying sections are ensured to separate light components; the product has extremely high purity: the whole process adopts silicon carbide and fluorine materials, and realizes "full non-metallic" contact. Through testing, the contents of main metal ions, Fe, Na, K and Ca, in the prepared trifluoroacetic acid are all lower than 5 ppb, which fully meets the requirements of semiconductor cleaning agents and etching liquids.

Description

Technical Field

[0001] This invention belongs to the field of chemical material preparation technology, and particularly relates to a method for preparing electronic-grade trifluoroacetic acid and a silicon carbide structured packing distillation apparatus. Background Technology

[0002] Trifluoroacetic acid (TFA), an important fluorinated organic intermediate, is widely used in pharmaceuticals, pesticides, and peptide synthesis. With the development of the microelectronics industry, the demand for electronic-grade trifluoroacetic acid (metal ion content <10 ppb, purity >99.9%) is increasing. Current purification technologies mainly suffer from the following problems: 1. Material corrosion and metal contamination: Traditional processes often use distillation columns made of 316L stainless steel or Hastelloy. Although Hastelloy has good corrosion resistance, trace amounts of metal ions can still precipitate out under high-temperature, concentrated acid conditions, leading to excessive metal ion content in the product and making it difficult to meet electronic grade requirements.

[0003] 2. Low mass transfer efficiency and high energy consumption: To avoid metal contamination, some companies use glass towers or PTFE-lined towers filled with ceramic random packing (such as Raschig rings and rectangular saddle rings). Random packing has a small specific surface area and disordered gas-liquid contact paths, resulting in a large height of equal plates (HETP), low separation efficiency, and the need for extremely high reflux ratios (typically >10:1), leading to huge energy consumption and low production efficiency.

[0004] 3. Poor internal component compatibility: Existing PTFE packing is prone to creep deformation at high temperatures, resulting in uneven gas-liquid distribution inside the tower, causing severe wall flow effects and poor long-term operational stability.

[0005] Therefore, developing a distillation process that can withstand strong acid corrosion, eliminate metal contamination, and maintain high mass transfer efficiency is an urgent need for the industry. Summary of the Invention

[0006] This invention provides a method for preparing electronic-grade trifluoroacetic acid and a silicon carbide structured packing distillation apparatus, aiming to solve: 1. completely eliminate the problem of metal ion contamination caused by traditional metal equipment; 2. improve gas-liquid mass transfer efficiency and reduce energy consumption by utilizing the high thermal conductivity and special surface treatment technology of silicon carbide materials; 3. realize the continuous and large-scale production of high-purity electronic-grade trifluoroacetic acid.

[0007] The present invention is implemented as follows: a method for preparing electronic-grade trifluoroacetic acid, comprising the following steps: S1: raw material preheating and feeding; S2: Gas-liquid mass transfer and separation: The material undergoes countercurrent gas-liquid mass transfer in the distillation column; S3: Multi-stage extraction and product collection.

[0008] S1 includes: S1-1: Raw material preheating: Industrial-grade trifluoroacetic acid raw material with a purity of 98%~99% is heated to the bubble point temperature through a graphite or silicon carbide preheater, with a temperature range of 40℃~60℃.

[0009] S1-2: Feed: The material enters the distillation column via the feed distributor. From bottom to top, the feed position is set at 1 / 3 to 1 / 2 of the column body to ensure sufficient rectification section for the separation of light components.

[0010] Preferably, S2 includes: S2-1: Operating pressure control: Operating at atmospheric pressure or slightly negative pressure, with the absolute pressure at the top of the column controlled between 0.08 MPa and 0.10 MPa. Slightly negative pressure operation helps to reduce the operating temperature and suppress the trace decomposition of trifluoroacetic acid and its corrosive effect on the equipment.

[0011] S2-2: Temperature control: The temperature of the bottom of the column is controlled at 72℃~85℃, and the temperature of the top of the column is controlled at 70℃~74℃.

[0012] S2-3: Reflux Ratio Control: Based on the high separation efficiency of silicon carbide structured packing, the reflux ratio R is set to 3:1~6:1. At this low reflux ratio, the high specific surface area of ​​the packing is used to achieve sufficient gas-liquid exchange, significantly reducing the heat load of the reboiler.

[0013] Preferably, S3 includes: S3-1: Top of the column: enriching low-boiling-point impurities, such as HF, water, and non-condensable gases, and after condensation, part of them are refluxed and part of them are collected as light component waste liquid.

[0014] S3-2: Boiler discharge: High-boiling-point heavy components, such as polymers and high-boiling-point acid impurities, are discharged from the bottom of the column.

[0015] S3-3: Side-stream extraction: A side-stream extraction outlet is set in the lower part of the rectification section or the upper part of the stripping section of the distillation column to extract electronic-grade trifluoroacetic acid product in either the gas or liquid phase. Side-stream extraction can effectively avoid trace light components that may accumulate at the top of the column and the heavy metal ion accumulation zone in the bottom of the column.

[0016] A silicon carbide structured packing distillation apparatus includes a distillation column, a feed inlet at the feed end of the distillation column, an external platform at the top end of the distillation column, a side stream collection and discharge mechanism on the outer wall of the distillation column, a side stream collection and collection assembly on the outer wall of the distillation column, a collection bottle connected to the discharge end of the side stream collection and collection assembly, a cooling mechanism on the outer wall of the distillation column, a sealing mechanism in the side stream collection and collection assembly, and a control valve in the side stream collection and collection assembly; the interior of the distillation column contains packing, a liquid distributor, and a support grid, with the distributor located below the feed inlet; The packing material is a multi-layer silicon carbide structured packing; the liquid distributor is located below the feed inlet, and the support grid is located between two adjacent layers of silicon carbide structured packing to distribute the material to be separated evenly in the tower plane and drip downwards. The support grid is located between the packing layers. The distillation column body is made of carbon steel lined with PFA or PTFE, with a lining thickness of 3mm to 5mm. It adopts plate lining or roller lining process to ensure that there is no exposed metal. Liquid distributor: A trough-type or tubular distributor is used, made of sintered silicon carbide or high-purity PTFE. The distribution point density is designed to be 100~150 points / m² to ensure uniform initial liquid distribution.

[0017] Liquid collector and support: The grid support is made of silicon carbide material. The high compressive strength of silicon carbide (>200 MPa) solves the problem of gravity support for the packing layer. The coefficient of thermal expansion is consistent with that of the packing, avoiding thermal stress damage under thermal cycling.

[0018] Preferably, the side-line extraction and discharge mechanism includes a discharge control assembly slidably disposed on the inner wall of the distillation column and a linear discharge port opened on the distillation column body; The control and discharge assembly includes a control motor fixedly mounted on the outer wall of the distillation column and a strip slider slidably connected to the inner wall of the distillation column. A sealing plate is fixedly connected to the outer wall of the strip slider, and a matching discharge port is opened on the outer wall of the sealing plate. The output shaft of the control motor is fixedly connected to a control gear through a coupling, and the outer wall of the strip slider has a toothed groove that mates with the control gear. By operating the control motor, the control gear is driven to rotate. Because the control gear and the toothed groove on the strip slider work together, the strip slider and the sealing plate can be driven to slide along the inner wall of the distillation column. When the matching discharge port coincides with the linear discharge port, the channel opens, and the gas phase of electronic-grade trifluoroacetic acid product is discharged along it, which can effectively avoid the trace light components that may be enriched at the top of the column and the heavy metal ion accumulation area at the bottom of the column.

[0019] Preferably, the side-line collection assembly includes an outer connector fixedly connected to the outer wall of the distillation column, an upper hanger fixedly connected to the top of the outer connector, and a discharge hole provided on the inner wall of the outer connector; wherein, the discharge hole cooperates with the linear discharge port for material discharge, and the collection bottle is inserted and installed in the discharge hole; The control valve includes a remote control base fixedly mounted on the upper end of the external base. The control end of the remote control base is connected to a hemispherical block, which is disposed on the inner wall of the discharge hole. The remote control base contains a remote control receiver and control circuit board and a micro control motor. Through the remote control valve, the discharge hole can be controlled to open and close.

[0020] Preferably, the sealing mechanism includes a sealing assembly fixedly connected to the inner wall of the upper hanger, and the inner wall of the sealing assembly is provided with a sealing component; wherein, the outer wall of the sealing component is in contact with the air inlet of the collection bottle; The sealing assembly includes a lifting hydraulic cylinder fixedly installed on the inner wall of the upper hanger. The telescopic end of the lifting hydraulic cylinder is fixedly connected to a sealing seat. A tear hole is provided on one side of the sealing seat. By inserting the collection bottle into the tear hole, the sealing film attached to the outer wall of the collection bottle mouth can be torn off. At the same time, the internal air pressure of the collection bottle is reduced due to external cooling, and the sealing film is tightly adsorbed at the collection bottle mouth, temporarily sealing it. The sealing assembly includes a take-up and release component fixedly installed on the inner wall of the sealing seat. The outer wall of the take-up and release component is provided with a sealing film, and the outer wall of the sealing film is in close contact with the outer wall of the sealing seat. The take-up and release component includes two micro motors embedded in the inner wall of the sealing seat. The output shaft of the micro motor is fixedly connected to the take-up and release shaft through a coupling. The outer walls of the two take-up and release shafts are respectively connected to both ends of the sealing film. They can be operated at the same frequency to realize the replacement of the sealing film.

[0021] Preferably, the cooling mechanism includes a rotary motor and a water distribution tank fixedly mounted on the outer wall of the distillation column. The output shaft of the rotary motor is fixedly connected to a connecting shaft via a coupling. A connecting frame is fixedly connected to the outer wall of one end of the connecting shaft. A wrap-around cooling water tank is fixedly connected to the outer wall of one end of the connecting frame. A micro pump is fixedly connected to the outer wall of the water distribution tank. The enclosed cooling water tank includes an upper water tank and a lower water tank. The bottom of the upper water tank has a drain hole, and the top of the lower water tank is connected to a connecting pipe. A sealing spring is embedded in the inner wall of the upper water tank, and a sealing plate is fixedly connected to one end of the sealing spring. When the connecting pipe is inserted into the drain hole, it is squeezed and contracted by the sealing plate, connecting the upper and lower water tanks. After the connecting pipe is pulled out, the upper and lower water tanks separate. Under the action of the sealing spring, the sealing plate returns to its original position, sealing the drain hole and preventing water from leaking out of the upper water tank. The micro pump is connected to the water distribution tank via a hose, and the micro pump is connected to the lower water tank via a hose. The upper water tank and the water distribution tank are also connected via a hose. When the upper and lower water tanks are connected, the micro pump is started to discharge cold water into the lower water tank. After the lower water tank is full, the water enters the upper water tank. When the upper water tank is full, the water flows back to the water distribution tank. The cooling mechanism, used in conjunction with the collection bottle, can cool and liquefy the trifluoroacetic acid collected in the collection bottle, thereby obtaining trifluoroacetic acid materials in different states.

[0022] Compared with the prior art, the embodiments of this application have the following main advantages: 1. Extremely high product purity: The entire process utilizes silicon carbide and fluorine materials, achieving "fully non-metallic" contact. Testing shows that the content of major metal ions such as Fe, Na, K, and Ca in the produced trifluoroacetic acid is all below 5 ppb, fully meeting the requirements for semiconductor cleaning agents and etching solutions. 2. Significantly improved production efficiency: The modified silicon carbide structured packing used has a plate height that is only 1 / 3 to 1 / 2 that of traditional ceramic random packing. This means that at the same tower height, the theoretical number of plates can be more than doubled, or the tower height can be significantly reduced while achieving the same separation effect. 3. Energy saving and consumption reduction: Due to its high mass transfer efficiency, it can operate at a lower reflux ratio of 3:1 to 6:1, while traditional processes require a reflux ratio of 10:1 or higher, reducing steam consumption by about 30%-40%; 4. Corrosion resistance and long service life: Silicon carbide materials have excellent chemical corrosion resistance and wear resistance, and will not creep at high temperatures like plastic fillers, thus extending the equipment maintenance cycle. Verified by a 600mm test tower, its performance has not degraded after 2000 hours of continuous operation. 5. The beneficial effects of using the side-stream extraction and discharge mechanism, collection components, sealing mechanism, and control valve in conjunction; the coordinated design of this series of mechanisms jointly constructs a precise, automated, fully enclosed, and contamination-proof side-stream extraction system. Its core beneficial effect lies in achieving targeted, sterile, and safe collection of high-purity products such as electronic-grade trifluoroacetic acid; the interlocking mechanisms achieve a high degree of automation and cleanliness in the extraction process, greatly improving the product quality stability and operational safety. Attached Figure Description

[0023] Figure 1 This is a front view of a silicon carbide structured packing distillation apparatus according to the present invention; Figure 2 This is a schematic diagram of the side-stream extraction and discharge mechanism in a silicon carbide structured packing distillation apparatus according to the present invention. Figure 3 This is a schematic diagram of the structure of the control and discharge assembly in a silicon carbide structured packing distillation apparatus according to the present invention; Figure 4 This is a schematic diagram of the connection structure of the central control valve, the side stream collection assembly, and the sealing mechanism in a silicon carbide structured packing distillation apparatus according to the present invention. Figure 5 This is a schematic diagram of the side stream collection component in a silicon carbide structured packing distillation apparatus according to the present invention. Figure 6 This is a schematic diagram of the sealing mechanism in a silicon carbide structured packing distillation apparatus according to the present invention; Figure 7 This is a schematic diagram of the structure of the control valve in a silicon carbide structured packing distillation apparatus according to the present invention; Figure 8 This is a schematic diagram of the cooling mechanism in a silicon carbide structured packing distillation apparatus according to the present invention; Figure 9 This is a schematic diagram of the connection structure of the upper water tank, lower water tank, connecting pipe, sealing spring, and sealing plate in a silicon carbide structured packing distillation apparatus according to the present invention.

[0024] In the diagram: 1. Distillation column body; 2. Feed inlet; 3. Control valve; 301. Remote control base; 302. Hemispherical plug; 4. External display stand; 5. Side stream discharge mechanism; 501. Linear discharge outlet; 502. Control assembly; 5021. Sealing plate; 5022. Matching discharge port; 5023. Control motor; 5024. Control gear; 5025. Strip slider; 6. Collection bottle; 7. Cooling mechanism; 701. Rotary control motor; 702. Enclosed cooling water tank; 7021. Lower water tank; 7022, Upper water tank; 7023, Connecting pipe; 7024, Sealing spring; 7025, Sealing plate; 703, Connecting frame; 704, Water distribution tank; 705, Micro pump; 8, Side line extraction and collection assembly; 801, External connector; 802, Discharge hole; 803, Upper hanger; 9, Sealing mechanism; 901, Sealing assembly; 9011, Lifting hydraulic cylinder; 9012, Sealing seat; 9013, Tear hole; 902, Sealing assembly; 9021, Sealing film; 9022, Receiving and releasing component. Detailed Implementation

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] This invention provides a method for preparing electronic-grade trifluoroacetic acid and a silicon carbide structured packing distillation apparatus, including the following steps: S1: raw material preheating and feeding; S2: Gas-liquid mass transfer and separation: The material undergoes countercurrent gas-liquid mass transfer in the distillation column; S3: Multi-stage extraction and product collection.

[0028] S1 includes: S1-1: Raw material preheating: Industrial-grade trifluoroacetic acid raw material with a purity of 98%~99% is heated to the bubble point temperature through a preheater made of graphite or silicon carbide, with a temperature range of 40℃~60℃.

[0029] S1-2: Feed: The material enters the distillation column via the feed distributor. From bottom to top, the feed position is set at 1 / 3 to 1 / 2 of the column body to ensure sufficient rectification section for the separation of light components.

[0030] S2 includes: S2-1: Operating pressure control: Operate at atmospheric pressure or slightly negative pressure, with the absolute pressure at the top of the column controlled between 0.08 MPa and 0.10 MPa. Slightly negative pressure operation helps reduce operating temperature and inhibits the trace decomposition of trifluoroacetic acid and its corrosive effect on equipment.

[0031] S2-2: Temperature control: The temperature of the bottom of the column is controlled at 72℃~85℃, and the temperature of the top of the column is controlled at 70℃~74℃.

[0032] S2-3: Reflux Ratio Control: Based on the high separation efficiency of silicon carbide structured packing, the reflux ratio R is set to 3:1~6:1. At this low reflux ratio, the high specific surface area of ​​the packing is used to achieve sufficient gas-liquid exchange, significantly reducing the heat load of the reboiler.

[0033] S3 includes: S3-1: Top of the column: enriches low-boiling-point impurities, such as HF, moisture, and non-condensable gases, and after condensation, part of it is refluxed and part of it is collected as light component waste liquid.

[0034] S3-2: Boiler discharge: High-boiling-point heavy components, such as polymers and high-boiling-point acid impurities, are discharged from the bottom of the column.

[0035] S3-3: Side-stream extraction: A side-stream extraction outlet is set in the lower part of the rectification section or the upper part of the stripping section of the distillation column to extract electronic-grade trifluoroacetic acid product in either the gas or liquid phase. Side-stream extraction can effectively avoid trace light components that may accumulate at the top of the column and the heavy metal ion accumulation zone in the bottom of the column.

[0036] It should be noted that: 1. It completely solves the problem of metal ion pollution caused by traditional metal equipment; 2. It improves gas-liquid mass transfer efficiency and reduces energy consumption by utilizing the high thermal conductivity and special surface treatment technology of silicon carbide materials; 3. It enables the continuous and large-scale production of high-purity electronic-grade trifluoroacetic acid.

[0037] In a further preferred embodiment of the present invention, a silicon carbide structured packing distillation apparatus includes a distillation column 1, a feed inlet 2 at the feed end of the distillation column 1, an outer platform 4 at the top end of the distillation column 1, a side stream collection and discharge mechanism 5 on the outer wall of the distillation column 1, a side stream collection and collection assembly 8 on the outer wall of the distillation column 1, a collection bottle 6 connected to the discharge end of the side stream collection and collection assembly 8, a cooling mechanism 7 on the outer wall of the distillation column 1, a sealing mechanism 9 in the side stream collection and collection assembly 8, a control valve 3 in the side stream collection and collection assembly 8, and packing, a liquid distributor and a support grid inside the distillation column 1, with the distributor located below the feed inlet 2; The packing material is a multilayer silicon carbide structured packing; the liquid distributor is located below the feed inlet 2 to distribute the material to be separated evenly in the tower plane and drip downwards; the support grid is located between two adjacent layers of silicon carbide structured packing. Among them, the material of the distillation column body 1 is carbon steel lined with PFA or PTFE, the lining thickness is 3mm~5mm, and plate lining or roller lining process is adopted to ensure that there is no exposed metal. Liquid distributor: A trough-type or tubular distributor is used, made of sintered silicon carbide or high-purity PTFE. The distribution point density is designed to be 100~150 points / m² to ensure uniform initial liquid distribution; Liquid collector and support: The grid support is made of all silicon carbide material. The high compressive strength of silicon carbide (>200 MPa) solves the problem of gravity support for the packing layer. Moreover, the coefficient of thermal expansion is consistent with that of the packing, avoiding thermal stress damage under thermal cycling. The side-stream extraction and discharge mechanism 5 includes a control and discharge assembly 502 that is slidably disposed on the inner wall of the distillation column body 1 and a linear discharge port 501 opened on the distillation column body 1; The control assembly 502 includes a control motor 5023 fixedly mounted on the outer wall of the distillation column 1 and a strip slider 5025 slidably connected to the inner wall of the distillation column 1. A sealing plate 5021 is fixedly connected to the outer wall of the strip slider 5025, and a discharge port 5022 is formed on the outer wall of the sealing plate 5021. The output shaft of the control motor 5023 is fixedly connected to a control gear 5024 via a coupling. The outer wall of the strip slider 5025 has a toothed groove that mates with the control gear 5024. By controlling the motor 5023, the control gear 5024 is driven to rotate. Because the control gear 5024 and the tooth groove on the strip slider 5025 are used in conjunction, the strip slider 5025 and the sealing plate 5021 can be driven to slide along the inner wall of the distillation column 1. When the discharge port 5022 coincides with the linear discharge port 501, the channel is opened, and the gas phase electronic grade trifluoroacetic acid product is discharged along the channel, which can effectively avoid the trace light components that may be enriched at the top of the column and the heavy metal ion accumulation area at the bottom of the column. The side-stream collection assembly 8 includes an outer seat 801 fixedly connected to the outer wall of the distillation column 1. An upper hanger 803 is fixedly connected to the top of the outer seat 801. A discharge hole 802 is opened on the inner wall of the outer seat 801. The discharge hole 802 cooperates with the linear discharge port 501 to discharge material. The collection bottle 6 is inserted and installed in the discharge hole 802. The control valve 3 includes a remote control base 301 fixedly mounted on the upper end of the external base 801. The control end of the remote control base 301 is connected to a hemispherical block 302, which is located on the inner wall of the discharge hole 802. The remote control base 301 contains a remote control receiver and control circuit board and a micro control motor. Through the remote control valve 3, the discharge hole 802 can be controlled to open and close. The sealing mechanism 9 includes a sealing component 901 fixedly connected to the inner wall of the upper hanger 803, and a sealing component 902 is provided on the inner wall of the sealing component 901; wherein, the outer wall of the sealing component 902 is in contact with the air inlet of the collection bottle 6. The sealing assembly 901 includes a lifting hydraulic cylinder 9011 fixedly installed on the inner wall of the upper hanger 803. The telescopic end of the lifting hydraulic cylinder 9011 is fixedly connected to a sealing seat 9012. A tear hole 9013 is provided on one side of the sealing seat 9012. By inserting the collection bottle 6 into the tear hole 9013, the sealing film 9021 attached to the outer wall of the bottle mouth of the collection bottle 6 can be torn off. At the same time, the internal air pressure of the externally cooled collection bottle 6 decreases, and the sealing film 9021 is tightly adsorbed at the mouth of the collection bottle 6, temporarily sealing it. The sealing assembly 902 includes a take-up and release component 9022 fixedly installed on the inner wall of the sealing seat 9012. The outer wall of the take-up and release component 9022 is provided with a sealing film 9021, and the outer wall of the sealing film 9021 is in close contact with the outer wall of the sealing seat 9012. The take-up and release component 9022 includes two micro motors embedded in the inner wall of the sealing seat 9012. The output shaft of the micro motor is fixedly connected to the take-up and release shaft through a coupling. The outer walls of the two take-up and release shafts are respectively connected to the two ends of the sealing film 9021. They can be operated at the same frequency to realize the replacement of the sealing film 9021. The cooling mechanism 7 includes a rotary motor 701 and a water distribution tank 704 fixedly installed on the outer wall of the distillation column 1. The output shaft of the rotary motor 701 is fixedly connected to a connecting shaft via a coupling. A connecting frame 703 is fixedly connected to the outer wall of one end of the connecting shaft. A wrap-around cooling water tank 702 is fixedly connected to the outer wall of one end of the connecting frame 703. A micro pump 705 is fixedly connected to the outer wall of the water distribution tank 704. The enclosed cooling water tank 702 includes an upper water tank 7022 and a lower water tank 7021. The bottom of the upper water tank 7022 has a drain hole, and the top of the lower water tank 7021 is connected to a connecting pipe 7023. A sealing spring 7024 is embedded in the inner wall of the upper water tank 7022, and a sealing plate 7025 is fixedly connected to one end of the sealing spring 7024. When the connecting pipe 7023 is inserted into the drain hole, it is squeezed and contracted by the sealing plate 7025, and the upper water tank 7022 and the lower water tank 7021 are connected. After the connecting pipe 7023 is pulled out, the upper water tank 7022 and the lower water tank 7021 are separated. Under the action of the sealing spring 7024, the sealing plate 7025 returns to its original position and seals the drain hole to prevent water from leaking out of the upper water tank 7022. The micro pump 705 is connected to the water distribution tank 704 via a hose, the micro pump 705 is connected to the lower water tank 7021 via a hose, and the upper water tank 7022 is connected to the water distribution tank 704 via a hose. When the upper water tank 7022 and the lower water tank 7021 are connected, the micro pump 705 is started to discharge cold water into the lower water tank 7021. After the lower water tank 7021 is full, the water enters the upper water tank 7022. When the upper water tank 7022 is full, the water flows back to the water distribution tank 704. The cooling mechanism 7, used in conjunction with the collection bottle 6, can cool and liquefy the trifluoroacetic acid collected in the collection bottle 6, thereby obtaining trifluoroacetic acid materials in different states. Among them, the structure selection of silicon carbide structured packing is as follows: a corrugated plate structure is adopted, with a corrugation angle of 45° for Y type or 60° for X type, depending on the throughput requirements; Geometric parameters: The specific surface area of ​​the packing is 250 m² / m³ to 500 m² / m³, and the porosity is ≥70%.

[0038] Surface microstructure: The filler surface is roughened by sandblasting or chemical etching to form a micron-level uneven structure. This treatment results in a contact angle of trifluoroacetic acid liquid on the filler surface of <30°, significantly improving the wettability of the liquid, eliminating the "channeling" phenomenon of traditional ceramic fillers at low spray densities, and maximizing the effective mass transfer area.

[0039] The workflow of this device follows the basic logic of continuous or batch distillation and side-stream extraction, and the specific steps are as follows: Feeding and Separation: The raw material trifluoroacetic acid mixture enters the distillation column 1 through feed inlet 2. After being evenly distributed by the liquid distributor, it enters the packing layer. In the packing layer, the gas and liquid phases come into countercurrent contact for mass and heat transfer. Utilizing the differences in volatility of the components in the mixture, the lighter components are enriched at the top of the column, while the heavier components are enriched at the bottom of the column. The target product, electronic-grade trifluoroacetic acid, reaches its highest concentration at a certain theoretical plate in the middle of the column.

[0040] Sidestream extraction preparation: Once the separation process is stable and the concentration distribution within the tower meets the requirements, product extraction is prepared. First, by controlling the motor 5023, the strip slider 5025 and the sealing plate 5021 are driven to slide, so that the matching discharge port 5022 on the sealing plate 5021 is precisely aligned with the linear discharge port 501 on the tower wall, opening the product gas phase extraction channel within the tower.

[0041] Product collection and sealing: The remote control opens the control valve 3, causing the hemispherical block 302 to leave the discharge hole 802 and connect the discharge channel of the external connector 801.

[0042] The lifting hydraulic cylinder 9011 of the sealing mechanism 9 is activated, driving the sealing seat 9012 to descend. At the same time, the bottle mouth of the collection bottle 6 is pushed inward and pressed into the tear hole 9013. During this process, the bottle mouth tears the sealing film 9021, and the bottle mouth is then temporarily sealed by merging with the film due to the low pressure generated by the pre-cooling inside the bottle.

[0043] High-purity trifluoroacetic acid gaseous material flows out from the open linear outlet 501 and enters the collection bottle 6 through the discharge hole 802 of the external connector 801.

[0044] Product Cooling and Collection: The cooling mechanism 7 is activated simultaneously with or slightly before the material enters the collection bottle 6. The rotary motor 701 rotates the connecting frame 703, causing the enclosed cooling water tank 702 to surround and tightly adhere to the collection bottle 6. The micro pump 705 pumps the cooling water from the distribution tank 704 into the lower water tank 7021 and fills the upper water tank 7022, circulating and cooling the collection bottle 6, causing the trifluoroacetic acid vapor entering the bottle to rapidly condense and liquefy.

[0045] Collection Completion and Reset: After the predetermined amount of product has been collected, firstly, the lifting hydraulic cylinder 9011 is operated to raise the bottle, causing the bottle mouth of collection bottle 6 to disengage from the sealing seat 9012. Then, the control valve 3 is remotely closed, and the hemispherical plug 302 resets to block the discharge hole 802. Finally, the control motor 5023 is operated to slide the sealing plate 5021, closing the linear discharge outlet 501. The full collection bottle 6 is removed, completing one product collection cycle. The take-up and release component 9022 in the sealing mechanism 9 can replace a new sealing film 9021, preparing for the next collection. In this embodiment, the packing material is made of silicon carbide, whose inherent high chemical inertness, excellent thermal stability, and mechanical strength ensure that no impurities such as metal ions are introduced when processing highly corrosive and high-purity materials such as trifluoroacetic acid, fundamentally guaranteeing product purity. This makes it particularly suitable for the preparation of electronic-grade chemicals. Secondly, the assembly adopts a regular corrugated plate structure with a Y-shape of 45° or an X-shape of 60°. This design creates continuous and regular gas-liquid flow channels, significantly reducing pressure drop, increasing column throughput and processing capacity, and reducing liquid backmixing. This makes the mass transfer driving force closer to the ideal countercurrent state, thereby improving separation efficiency. The most critical innovation lies in the micron-level uneven structure formed on the packing surface through sandblasting roughening or chemical etching. This treatment reduces the contact angle of trifluoroacetic acid liquid on the packing surface to below 30°, greatly improving the liquid's wetting and spreading properties. This effectively eliminates the industry problem of uneven liquid distribution and easy formation of "channeling" under low spray density, so that the liquid can uniformly cover the surface of the packing, maximize the utilization of its high specific surface area of ​​250-500 m² / m³, ensure full and uniform contact between the gas and liquid phases, and achieve efficient mass transfer and separation. In this embodiment, the side-stream extraction and discharge mechanism 5, driven by a motor, slides the sealing plate 5021, precisely controlling the opening position of the linear discharge port 501. This allows the operator to flexibly select the optimal gas phase extraction point within the tower, accurately avoiding the trace light components that may accumulate at the top of the tower and the heavy metal ion accumulation zone at the bottom, directly extracting the product from the "essence section" with the highest purity, fundamentally ensuring the initial purity of the product. The side-stream extraction and collection component 8 and the control valve 3 form a bridge between receiving and controlling. The remotely operated hemispherical plug 302 enables remote and precise control of pipeline opening and closing, avoiding delays and errors caused by manual operation. The sealing mechanism 9 is the key to the anti-contamination design of this system. It innovatively integrates the "puncture-temporary seal" function into the lifting action: when the collection bottle 6 is pushed in by the hydraulic cylinder, the bottle mouth automatically punctures the sealing film 9021; simultaneously, due to the pre-cooling of the bottle body causing a decrease in internal air pressure, the film is tightly adsorbed onto the bottle mouth to form a temporary seal, effectively isolating air during the extraction process. The 9022 receiving and discharging unit enables automatic replacement of the sealing film, preparing it for the next collection. The entire process, from opening the tower and discharging the material through the pipeline to sealing the bottle mouth, is completed automatically under closed or negative pressure conditions, completely eliminating contamination of the ultrapure product by external air, moisture, and particulate matter, and meeting the extremely clean production environment requirements of electronic-grade chemicals.

[0046] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0047] It should be understood that the disclosed apparatus can be implemented in other ways, given the several embodiments provided in this application. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units described above may be implemented in other ways in practice. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or communication connections shown or discussed may be through some interfaces; indirect coupling or communication connections between devices or units may be telecommunications or other forms.

[0048] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for preparing electronic-grade trifluoroacetic acid, characterized in that, Includes the following steps: S1: Raw material preheating and feeding; S2: Gas-liquid mass transfer and separation: The material undergoes countercurrent gas-liquid mass transfer in the distillation column; S3: Multi-stage extraction and product collection.

2. The method for preparing electronic-grade trifluoroacetic acid as described in claim 1, characterized in that, S1 includes: S1-1: Raw material preheating: Industrial-grade trifluoroacetic acid raw material with a purity of 98%~99% is heated to the bubble point temperature through a preheater made of graphite or silicon carbide, with a temperature range of 40℃~60℃. S1-2: Feed: The material enters the distillation column through the feed distributor. From bottom to top, the feed position is set at 1 / 3 to 1 / 2 of the column body.

3. The method for preparing electronic-grade trifluoroacetic acid as described in claim 1, characterized in that, S2 includes: S2-1: Operating pressure control: Operating at atmospheric pressure or slightly negative pressure, with the absolute pressure at the top of the column controlled at 0.08 MPa ~ 0.10 MPa; S2-2: Temperature control: The temperature of the bottom of the column is controlled at 72℃~85℃, and the temperature of the top of the column is controlled at 70℃~74℃; S2-3: Reflux ratio control: Based on the high separation efficiency of silicon carbide structured packing, the reflux ratio R is set to 3:1~6:

1.

4. The method for preparing electronic-grade trifluoroacetic acid as described in claim 1, characterized in that, S3 includes: S3-1: Top of the column: enriching low-boiling-point impurities, including one or more of HF, water, and non-condensable gases, which are partially refluxed after condensation and partially collected as light component waste liquid. S3-2: Boiler discharge: High-boiling-point heavy components, including polymers and high-boiling-point acid impurities, are discharged from the bottom of the column. S3-3: Side-stream extraction: A side-stream extraction outlet is set in the lower part of the rectification section or the upper part of the stripping section of the distillation column to extract electronic-grade trifluoroacetic acid product in gas or liquid phase.

5. A silicon carbide structured packing distillation apparatus, characterized in that, The method for preparing electronic-grade trifluoroacetic acid as described in claim 1 includes a distillation column (1), a feed inlet (2) at the feed end of the distillation column (1), an external platform (4) at the top end of the distillation column (1), a side stream collection and discharge mechanism (5) on the outer wall of the distillation column (1), a side stream collection and collection assembly (8) on the outer wall of the distillation column (1), a collection bottle (6) connected to the discharge end of the side stream collection and collection assembly (8), a cooling mechanism (7) on the outer wall of the distillation column (1), a sealing mechanism (9) in the side stream collection and collection assembly (8), a control valve (3) in the side stream collection and collection assembly (8), and packing, a liquid distributor and a support grid inside the distillation column (1), with the distributor located below the feed inlet (2).

6. The silicon carbide structured packing distillation apparatus as described in claim 5, characterized in that, The side-line extraction and discharge mechanism (5) includes a control and discharge assembly (502) slidably disposed on the inner wall of the distillation column (1) and a linear discharge port (501) opened on the distillation column (1). The control and discharge assembly (502) includes a control motor (5023) fixedly installed on the outer wall of the distillation column (1) and a strip slider (5025) slidably connected to the inner wall of the distillation column (1). A sealing plate (5021) is fixedly connected to the outer wall of the strip slider (5025). A discharge port (5022) is opened on the outer wall of the sealing plate (5021). The output shaft of the control motor (5023) is fixedly connected to a control gear (5024) through a coupling. A toothed groove that mates with the control gear (5024) is opened on the outer wall of the strip slider (5025).

7. The silicon carbide structured packing distillation apparatus as described in claim 5, characterized in that, The side line collection assembly (8) includes an outer connector (801) fixedly connected to the outer wall of the distillation column (1), an upper hanger (803) fixedly connected to the top of the outer connector (801), and a discharge hole (802) opened on the inner wall of the outer connector (801). The control valve (3) includes a remote control base (301) fixedly installed on the upper end of the external base (801). The control end of the remote control base (301) is connected to a hemispherical block (302), which is installed on the inner wall of the discharge hole (802).

8. The silicon carbide structured packing distillation apparatus as described in claim 7, characterized in that, The sealing mechanism (9) includes a sealing component (901) fixedly connected to the inner wall of the upper hanger (803), and the inner wall of the sealing component (901) is provided with a sealing component (902). The sealing assembly (901) includes a lifting hydraulic cylinder (9011) fixedly installed on the inner wall of the upper hanger (803). The telescopic end of the lifting hydraulic cylinder (9011) is fixedly connected to a sealing seat (9012). A tear hole (9013) is provided on one side of the sealing seat (9012). The sealing assembly (902) includes a take-up and release member (9022) fixedly disposed on the inner wall of the sealing seat (9012), and a sealing film (9021) is provided on the outer wall of the take-up and release member (9022), and the outer wall of the sealing film (9021) is in close contact with the outer wall of the sealing seat (9012).

9. The silicon carbide structured packing distillation apparatus as described in claim 5, characterized in that, The cooling mechanism (7) includes a rotary motor (701) and a water distribution tank (704) fixedly installed on the outer wall of the distillation column (1). The output shaft of the rotary motor (701) is fixedly connected to a connecting shaft via a coupling. A connecting frame (703) is fixedly connected to the outer wall of one end of the connecting shaft. A wrap-around cooling water tank (702) is fixedly connected to the outer wall of one end of the connecting frame (703). A micro pump (705) is fixedly connected to the outer wall of the water distribution tank (704). The enclosed cooling water tank (702) includes an upper water tank (7022) and a lower water tank (7021). The bottom of the upper water tank (7022) is provided with a drain hole, and the top of the lower water tank (7021) is connected to a connecting pipe (7023). A sealing spring (7024) is embedded in the inner wall of the upper water tank (7022), and a sealing plate (7025) is fixedly connected to one end of the sealing spring (7024).

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