High-quality electronic fluorination solution and preparation method thereof

Abstract

This invention discloses a high-quality electronic fluorinated liquid and its preparation method, relating to the field of fine chemicals. The method includes: selecting a branched perfluoro-2-methyl-3-oxahexane precursor; conducting a fluorine-free liquid-phase catalytic fluorination reaction with hydrogen fluoride under the action of a supported Lewis acid catalyst; sequentially purifying the liquid through a multi-stage gradient process involving molecular sieve adsorption for water removal, chelating resin for metal ion removal, and ultrafiltration membrane for particulate matter removal; further purifying the liquid by high-vacuum distillation to obtain a narrow-boiling-range fraction; and implementing closed-loop feedback control using an online moisture, metal ion, and particulate matter monitoring system. This invention aims to solve the problems of insufficient purity, poor process safety, and unsatisfactory thermophysical properties in existing electronic fluorinated liquids. The resulting product has extremely low moisture, metal ion, and particulate matter content, and possesses high dielectric strength, high thermal conductivity, and excellent long-term stability. Furthermore, the process is safe, environmentally friendly, and yields high amounts, making it suitable for high-end electronic fields such as semiconductor immersion cooling.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, and in particular to a high-quality electronic fluorinated liquid and its preparation method. Background Technology

[0002] With the increasing demands for thermal management performance in high-power electronic devices, data centers, and new energy battery systems, immersion liquid cooling technology has gradually become the mainstream solution for thermal management of high-end electronic devices due to its excellent heat dissipation density and system integration. Electronic fluorinated liquids, as the core heat transfer medium for immersion cooling, possess excellent electrical insulation, chemical inertness, low surface tension, and suitable thermophysical parameters. They can achieve efficient direct contact heat dissipation without damaging electronic components, and have broad application prospects in semiconductor manufacturing, aerospace electronic systems, and other fields. These fluorinated liquids are typically based on perfluoropolyethers, perfluoroalkanes, or their derivatives, and remove heat generated by components through single-phase convection or two-phase phase change thermal mechanisms. In practical engineering applications, high-quality electronic fluorinated liquids not only require a well-defined main component structure and concentrated boiling range, but also must meet extremely stringent purity requirements: moisture content below 1 ppm, total metal ion content not exceeding 0.1 ppb, and particle size ≥ 0.2 μm concentration not exceeding 10 particles / mL. The aforementioned indicators directly determine the chemical stability of the medium under long-term service conditions, its corrosion inertness to precision components, and its safety compatibility with sensitive devices. These are the core thresholds for whether electronic fluorinated liquids can enter cutting-edge scenarios such as advanced process semiconductor packaging, high-density computing chip cooling, and space electronic systems.

[0003] However, existing technologies still have significant shortcomings in the preparation of high-purity electronic fluorinated liquids. One existing technology proposes using hexafluoropropylene oxide tetramer acyl fluoride as raw material and employing a gas-gas reactive distillation process to prepare perfluoroether fluorinated liquids, removing residual fluorine by controlling the reflux ratio and preheating temperature. This method has a certain continuous production capability, but the synthesis route is highly dependent on the strong oxidizing and highly reactive fluorine gas, posing significant operational safety risks. Furthermore, the purification strategy only targets the removal of gaseous byproducts, lacking systematic and in-depth purification measures for key liquid-phase impurities such as moisture, dissolved metal ions, and fine particulate matter, making it difficult to achieve the UP-SS grade electronic chemical purity standard. Another existing technology constructs a composite cooling system composed of low-boiling-point and high-boiling-point fluorinated liquids, utilizing the synergistic effect of phase transition between components to improve overall heat dissipation efficiency. However, this scheme does not involve the synthesis or purification process of the main fluorinated liquid, leaving the intrinsic purity of the raw materials unclear. During long-term cyclic use, the composite system is also prone to component segregation and interfacial compatibility degradation, making it difficult to consistently guarantee the chemical consistency and cleanliness stability of the cooling medium.

[0004] In summary, existing technologies are either constrained by safety bottlenecks caused by highly active fluorine sources, or focus on optimizing the macroscopic performance of the cooling system while neglecting the precise control of the intrinsic purity of the medium. A complete electronic fluorinated liquid preparation system that can balance high purity, high safety, long-term stability, and feasibility of large-scale production has not yet been formed. Summary of the Invention

[0005] The purpose of this invention is to provide a high-quality electronic fluorinated liquid and its preparation method to solve the problems of insufficient purity, poor process safety, and unsatisfactory thermophysical properties of existing electronic fluorinated liquids.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A high-quality electronic fluorinated liquid and its preparation method, comprising:

[0008] Step 1: Select a perfluoropolyether precursor with a specific structure as the main raw material: The main raw material is perfluoro-2-methyl-3-oxahexane or its homologue with a branched structure, and its general molecular formula is CnF2n+2O, where n is an integer within a predetermined range, the boiling range is controlled within a preset temperature range, and the initial purity is not lower than a preset purity threshold.

[0009] Step 2, catalytic fluorination reaction without fluorine gas participation: the main raw material and hydrogen fluoride are subjected to liquid-phase catalytic fluorination reaction under the action of a supported Lewis acid catalyst and under preset temperature and pressure ranges. The reaction time is a predetermined time period to generate the target crude fluorinated liquid. This avoids the use of highly active element fluorine to eliminate safety risks.

[0010] Step 3, implement multi-stage gradient purification: First, remove water through a molecular sieve adsorption column to reduce the water content to below a preset water threshold; then, use a chelating resin column to deeply remove metal ions to reduce the total metal ion concentration to below a preset metal ion concentration threshold; finally, filter particulate matter through an ultrafiltration membrane system, wherein the ultrafiltration membrane pore size is a predetermined pore size, the operating pressure is a preset pressure range, and the flow rate is a predetermined flow rate range.

[0011] Step 4, perform high vacuum distillation purification: introduce the crude fluorinated liquid after multi-stage gradient purification into a high vacuum distillation column, and carry out distillation under the conditions that the absolute pressure is lower than the preset vacuum threshold, the column bottom temperature is within the preset temperature range, and the reflux ratio is within the predetermined ratio range. Collect the fraction with the boiling range concentrated in the preset narrow temperature range to obtain a high-purity intermediate product.

[0012] Step 5: Construct a closed-loop online monitoring and feedback control system: Install an online moisture analyzer, an inductively coupled plasma mass spectrometer, and a laser particle counter at the distillation outlet to monitor the concentrations of moisture, metal ions, and particulate matter in real time, and feed the data back to the central controller to dynamically adjust the distillation parameters and the operating status of the purification unit to ensure that the final product continuously meets the ultra-high purity index.

[0013] In step 1, the branched structure of the perfluoropolyether precursor contains at least one trifluoromethyl side chain. This structure can reduce intermolecular van der Waals forces, thereby improving thermal conductivity and maintaining low viscosity characteristics. Its kinematic viscosity at the standard test temperature is within a predetermined viscosity range, and its surface tension is within a predetermined surface tension range.

[0014] In step 2, the supported Lewis acid catalyst is a boron trifluoride complex supported on a porous silica support. The specific surface area of ​​the support is within a predetermined range, the pore size distribution is within a predetermined range, and the catalyst loading amount is within a predetermined ratio range of the mass of the reactants. After the reaction, it is recovered and reused by magnetic separation or filtration. After a single cycle, the activity retention rate is greater than or equal to the preset activity retention rate threshold.

[0015] In step 3, the molecular sieve adsorption column uses a 3A or 4A type molecular sieve with a predetermined particle size range, a predetermined bed height range, and a space velocity controlled within a predetermined space velocity range. The chelating resin is an iminodiacetic acid type or a mercapto-functionalized polystyrene resin with an exchange capacity greater than or equal to a preset exchange capacity threshold. The regeneration cycle is one acid-base elution regeneration after each treatment of a predetermined mass of material.

[0016] In step 4, the high-vacuum distillation column adopts an all-metal sealed structure, the inner wall is electrolytically polished, the surface roughness Ra is less than or equal to the preset roughness threshold, the number of trays is within a predetermined range, the theoretical tray efficiency is greater than or equal to the preset efficiency threshold, high-purity nitrogen is introduced as a protective atmosphere during the distillation process, and the oxygen content is controlled below the preset oxygen content threshold.

[0017] In step 5, the online moisture analyzer uses the cold mirror dew point method and the detection limit is a preset detection limit threshold. The inductively coupled plasma mass spectrometer is equipped with a collision reaction cell and can simultaneously monitor multiple key metal elements. The detection limit is lower than the preset metal detection limit threshold. The laser particle counter has a sampling flow rate of a predetermined sampling flow rate, a particle size detection range of a predetermined particle size interval, and a resolution of a predetermined resolution threshold.

[0018] It also includes accelerated stability testing of the final product: the prepared electronic fluorinated liquid is placed in a preset high temperature and high humidity environment and stored continuously for a predetermined time. The change in moisture before and after the test is less than or equal to the preset moisture change threshold, the increase in metal ions is less than or equal to the preset metal increase threshold, and the fluctuation in particulate matter concentration is less than or equal to the preset particulate matter fluctuation threshold, thus verifying its long-term chemical and physical stability.

[0019] The preparation method has an overall process yield greater than or equal to a preset yield threshold, a unit product energy consumption lower than a preset energy consumption threshold, and a waste liquid generation amount less than or equal to a preset waste liquid volume threshold. All process units are integrated into a closed pipeline system to achieve fully automated control of the entire process, and the daily production capacity of a single line can reach or exceed the predetermined production capacity threshold.

[0020] The final product of the high-quality electronic fluorinated liquid meets the following indicators: moisture content is less than or equal to the preset upper limit threshold for moisture, total metal ions are less than or equal to the preset upper limit threshold for total metal ions, particulate matter concentration is less than or equal to the preset upper limit threshold for particulate matter concentration (particle size is greater than or equal to the predetermined particle size threshold), dielectric strength is greater than or equal to the preset dielectric strength threshold, volume resistivity is greater than or equal to the preset resistivity threshold, and thermal conductivity is greater than or equal to the preset thermal conductivity threshold.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] This invention, through the synergistic effect of a fluorine-free gas catalytic synthesis route and a four-stage deep purification system, has for the first time achieved UP-SS level ultra-high purity for key impurity indicators such as moisture, metal ions, and particulate matter. It breaks through the bottleneck of existing technologies in the deep control of impurities and fully meets the stringent requirements of advanced semiconductor immersion cooling for media cleanliness.

[0023] This invention eliminates the use of highly reactive fluorine gas and adopts a liquid-phase catalytic fluorination reaction under mild conditions, fundamentally eliminating the risks of explosion and leakage. The fully enclosed design and efficient catalyst recovery mechanism significantly reduce energy consumption and waste liquid emissions, and the carbon footprint per unit product is significantly reduced compared to traditional gas-gas reaction processes, which is in line with the trend of green chemical development.

[0024] This invention innovatively introduces a branched perfluoropolyether structure, which optimizes thermophysical properties while ensuring excellent electrical insulation, and significantly improves thermal conductivity. The closed-loop online monitoring system ensures batch-to-batch consistency, and accelerated aging tests show that the product has minimal performance degradation under high temperature and high humidity conditions, which can support long-term maintenance-free operation in data centers or aerospace electronic systems. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall technical solution architecture of a high-quality electronic fluorinated liquid and its preparation method proposed in this invention;

[0026] Figure 2 This is a schematic diagram of the core principle framework of the catalytic fluorination reaction without fluorine gas participation and the synergistic control of four-stage deep purification in this invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0030] Step 1: Select a perfluoropolyether precursor with a specific structure as the main raw material. Specifically, the main raw material selected in Step 1 is perfluoro-2-methyl-3-oxahexane or its homologues with a branched structure, whose general molecular formula is CnF2n+2O, where n is an integer in the range of 6 to 12. The boiling range of this precursor is controlled between 85°C and 115°C, and the initial purity is not less than 99.5 wt%. The branched structure contains at least one trifluoromethyl (–CF3) side chain, which is attached to the carbon atom of the main chain, forming a steric hindrance effect, effectively weakening the intermolecular van der Waals forces, thereby improving the thermal conductivity while maintaining a low kinematic viscosity. At a standard test temperature of 25°C, the kinematic viscosity of this precursor is 0.8 mm² / s to 1.2 mm² / s, and the surface tension is 14 mN / m to 16 mN / m. The raw material storage tank is made of 316L stainless steel, with the inner wall electropolished to a surface roughness Ra≤0.4μm. It is equipped with a nitrogen-sealed protection system, controlling the oxygen content below 1ppm to prevent precursor degradation caused by trace moisture or oxygen introduction. Raw material delivery is accomplished via a diaphragm metering pump, with flow accuracy controlled within ±0.5%, ensuring the stability and repeatability of subsequent reaction feeds.

[0031] Step 2 involves a catalytic fluorination reaction without the participation of fluorine gas. Specifically, in Step 2, the main raw material obtained in Step 1 and anhydrous hydrogen fluoride (HF) are introduced into a fixed-bed reactor at a mass ratio of 1:1.05 to 1:1.20, and a liquid-phase catalytic fluorination reaction is carried out under the action of a supported Lewis acid catalyst. The supported Lewis acid catalyst is a complex formed by boron trifluoride (BF3) and diethyl ether, supported on a porous silica support with a specific surface area of ​​300 m² / g to 500 m² / g, a pore size distribution of 8 nm to 15 nm, and a pore volume of 0.8 cm³ / g to 1.2 cm³ / g. The catalyst loading is 1.5 wt% to 3.0 wt% of the total mass of the reactants, and is packed in the catalyst bed in the middle of the reactor. The bed height is 300 mm to 500 mm, and quartz wool is used for separation to prevent channeling. The reaction was carried out at temperatures ranging from 40°C to 70°C and pressures from 0.3 MPa to 0.6 MPa for 2 to 4 hours. During the reaction, hydrogen fluoride, in liquid form, came into full contact with the precursor and underwent an electrophilic substitution reaction at the active sites of the catalyst to generate the target crude fluorinated liquid, whose main component was a branched perfluoropolyether structure with a molecular weight distribution concentrated between 600 g / mol and 900 g / mol. After the reaction, unreacted hydrogen fluoride was separated and recycled through a condensation recovery system with a recovery rate of ≥98%. The catalyst achieved solid-liquid separation through an internal magnetic component or an external filter element, and the catalytic activity retention rate was ≥95% after a single cycle, and remained above 85% after 5 cycles. An online pH monitoring probe was installed at the reactor outlet to monitor the acidity of the reaction system in real time, ensuring that side reactions (such as over-fluorination or cracking) were suppressed within a controllable range.

[0032] Step 3 involves a multi-stage gradient purification process. Specifically, Step 3 comprises three continuous and irreversible purification sub-units: molecular sieve adsorption, chelating resin demetallization, and ultrafiltration membrane particle removal. First, the crude fluorinated liquid, preheated to 30°C, enters a molecular sieve adsorption column filled with type 3A or 4A molecular sieves with a particle size of 1.6 mm to 2.5 mm and a bed height of 800 mm to 1200 mm. The operating space velocity is controlled at 2 BV / h to 5 BV / h (BV is the bed volume). The molecular sieves are activated under vacuum at 300°C for 4 hours before loading, reducing the moisture content from an initial 50 ppm to ≤0.5 ppm. Subsequently, the dehydrated material flows into a chelating resin column. This resin is iminodiacetic acid (IDA) type or mercapto-functionalized polystyrene resin with a particle size of 0.3 mm to 0.8 mm, an exchange capacity ≥2.0 mmol / g, and a bed height of 600 mm to 1000 mm. At a flow rate of 3 BV / h, the resin achieves a removal efficiency of ≥99.9% for key metal ions such as Fe, Cu, Na, and K, reducing the total metal ion concentration from 10 ppb to ≤0.05 ppb. The resin regeneration cycle is set to be performed once after processing 500 kg of material. The regeneration procedure includes: first, eluting metal ions with 0.5 mol / L hydrochloric acid solution at a flow rate of 2 BV / h for 30 min; then rinsing with deionized water until neutral; and finally, activating with 0.1 mol / L sodium hydroxide solution for 20 min to restore exchange capacity. Finally, the demetallized liquid enters the ultrafiltration membrane system, which uses a hollow fiber membrane made of polytetrafluoroethylene (PTFE) with a pore size of 0.1 μm. The operating pressure is 0.15 MPa to 0.25 MPa, and the flow rate is 1.5 L / min to 2.5 L / min, operating in cross-flow filtration mode. The ultrafiltration process can reduce the concentration of particles with a diameter ≥0.2 μm from 100 particles / mL to ≤5 particles / mL. The entire purification process is carried out in a closed stainless steel pipeline, and all interfaces are sealed with VCR metal to prevent external contamination.

[0033] Step 4 involves high-vacuum distillation purification. Specifically, in step 4, the fluorinated liquid treated in step 3 is introduced into a high-vacuum distillation column. This column is an all-metal sealed structure made of 316L stainless steel, with the inner wall electropolished to a surface roughness Ra≤0.2μm to reduce impurity adsorption and retention. It has 20 to 30 trays, a theoretical tray efficiency ≥90%, and a high-efficiency condenser at the top, with the refrigerant temperature controlled at -20℃. Distillation is carried out under high vacuum conditions with an absolute pressure below 10Pa, the reboiler temperature is maintained at 120℃ to 150℃, and the reflux ratio is set to 5:1 to 10:1. Under these conditions, the boiling range of the target component is concentrated between 98℃ and 102℃ (at 10Pa). This narrow fraction is precisely captured by an automatic fraction collection valve to obtain a high-purity intermediate product. During the distillation process, high-purity nitrogen (≥99.999%) is continuously introduced as a protective atmosphere. The oxygen content in the system is monitored in real time by an online oxygen analyzer to ensure it remains ≤0.5ppm. The bottom liquid is periodically discharged and sent to a waste liquid treatment unit. The high-boiling-point impurities in the bottom liquid are ≥95%, which can be recycled as a byproduct. The distillation column is equipped with dual redundant temperature sensors and pressure transmitters, with a data sampling frequency of 1Hz, ensuring that process parameters remain stable within the set window. Through this step, the purity of the intermediate product reaches over 99.999wt%, laying the foundation for the final product.

[0034] Step 5: Construct a closed-loop online monitoring and feedback control system. Specifically, Step 5 integrates three sets of online analytical instruments on the distillation column outlet pipeline: an online moisture analyzer, an inductively coupled plasma mass spectrometer (ICP-MS), and a laser particle counter. The online moisture analyzer is based on the cold mirror dew point method, with a detection limit of 0.1 ppm, a response time ≤30 s, and a mirror temperature control accuracy of ±0.1℃. A PID algorithm is used to adjust the cooling power to maintain dew point stability. The ICP-MS is equipped with a helium collision reaction cell and can simultaneously monitor 12 key metallic elements, including Fe, Cu, Ni, Cr, Na, and K. The detection limits for each element are all below 0.01 ppb, and the data acquisition frequency is once per minute. The laser particle counter uses the light scattering principle, with a sampling flow rate of 100 mL / min, a particle size detection range of 0.1 μm to 5.0 μm, a resolution of 0.01 μm, and outputs a particle concentration distribution histogram every 5 minutes. Data from the three instruments is transmitted in real time to a central controller (PLC+SCADA system) via industrial Ethernet. The controller incorporates a multivariate predictive control (MPC) algorithm, dynamically adjusting the following parameters based on the deviation between measured values ​​and preset thresholds: if moisture > 0.8 ppm, the molecular sieve column regeneration frequency is increased; if total metal ion concentration > 0.08 ppb, the chelating resin regeneration cycle is shortened; if particulate matter concentration > 8 particles / mL (≥0.2 μm), the ultrafiltration membrane flow rate is reduced and a backwashing procedure is initiated; if the purity of the distillate fluctuates, the reflux ratio is fine-tuned by ±0.5 units or the reboiler temperature by ±2℃. This closed-loop system ensures that the final product consistently meets ultra-high purity standards, with a batch-to-batch relative standard deviation (RSD) ≤ 1.5%.

[0035] To further verify product performance, accelerated stability testing was conducted on the final electronic fluorinated liquid. 500 mL samples were continuously stored in a constant temperature and humidity chamber at 85℃ and 85%RH for 168 h. Before and after the test, the change in moisture content was ≤0.1 ppm, the increase in metal ions was ≤0.01 ppb, and the fluctuation in particulate matter concentration was ≤2 particles / mL (≥0.2 μm), indicating that the product exhibits excellent chemical and physical stability under high temperature and humidity conditions. The final product meets the following specifications: moisture content ≤1 ppm, total metal ions ≤0.1 ppb, particulate matter concentration ≤10 particles / mL (particle size ≥0.2 μm), dielectric strength ≥30 kV / mm, and volume resistivity ≥1×10¹. 5 Ω·cm, thermal conductivity ≥0.07W / m·K. The overall process yield of the entire preparation method is ≥92%, the energy consumption per unit product is ≤1.8kWh / kg, the waste liquid generation is ≤0.05L / kg, all process units are integrated into a closed pipeline system, and the entire process is fully automated by a DCS system. The daily production capacity of a single line can reach more than 2000kg.

[0036] To quantify the relationship between thermal conductivity and molecular structure, the following empirical formula is introduced to describe the correlation between the thermal conductivity λ of branched perfluoropolyethers and their kinematic viscosity ν:

[0037]

[0038] Where 'a' is a material constant ranging from 0.065 to 0.075, and 'b' is an exponential factor ranging from 0.15 to 0.25. This formula shows that, with optimized branched structure, reduced viscosity can directly improve thermal conductivity, which aligns with the design logic of this invention.

[0039] Furthermore, the theoretical plate number N in the distillation process and the separation efficiency η satisfy the following relationship:

[0040]

[0041] in, The purity of the fraction was determined by back-calculation using the Fenske equation and measured fraction purity. The results were obtained from AspenPlus simulations. In this invention, η≥90% ensures high selectivity for narrow-boiling-range fractions.

[0042] Example 2

[0043] In another embodiment, the main raw material selected in step 1 is a homologue of perfluoro-2-methyl-3-oxahexane, with n=8, molecular formula C8F18O, boiling range of 92℃ to 96℃ (at atmospheric pressure), and initial purity of 99.7wt%. In step 2, the supported catalyst uses a magnetic Fe3O4@SiO2-supported BF3 complex, with a specific surface area of ​​420 m² / g, pore size of 12 nm, and a loading of 2.0wt%. The reaction temperature is 55℃, the pressure is 0.45 MPa, and the reaction time is 3 h. After the reaction, the catalyst is rapidly separated by an external magnetic field, with a recovery rate of 99.5%. In step 3, a 4A type molecular sieve column with a particle size of 2.0 mm, a bed height of 1000 mm, and a space velocity of 3 BV / h was used. The chelating resin was a thiol-functionalized type with an exchange capacity of 2.3 mmol / g and a regeneration cycle of once per 600 kg of material. The ultrafiltration membrane had a pore size of 0.1 μm, an operating pressure of 0.2 MPa, and a flow rate of 2.0 L / min. In step 4, the distillation column had 25 trays, a vacuum of 8 Pa, a reboiler temperature of 135 °C, a reflux ratio of 8:1, and collected the fraction from 99 °C to 101 °C. In step 5, the online moisture analyzer had a detection limit of 0.08 ppm, the ICP-MS detection limit was 0.008 ppb, and the laser particle counter had a sampling flow rate of 100 mL / min. The final product had a moisture content of 0.7 ppm, a total metal ion content of 0.07 ppb, a particulate matter concentration of 8 particles / mL (≥0.2 μm), a thermal conductivity of 0.072 W / m·K, and a dielectric strength of 32 kV / mm. After accelerated aging testing (85℃ / 85%RH / 168h), all indicators remained within acceptable limits. This approach further validates the process robustness and product consistency of this invention under different raw material specifications.

[0044] Example 3

[0045] In another embodiment, the hydrogen fluoride in step 2 is replaced with a hydrogen fluoride-pyridine complex (HF-Py), with a molar ratio of main raw material:HF-Py = 1:1.1. The reaction temperature is reduced to 35°C, the pressure to 0.25 MPa, and the reaction time to 5 h to reduce corrosivity and improve selectivity. The catalyst is non-magnetic porous Al₂O₃ supported on BF₃, with a specific surface area of ​​350 m² / g, a pore size of 10 nm, and a packing weight of 2.5 wt%. After the reaction, it is recovered by filtration through a 0.2 μm sintered metal filter. In step 3, an activated carbon adsorption column is added after the molecular sieve column and chelating resin column are connected in series to remove trace organic byproducts. The activated carbon has an iodine value ≥1000 mg / g and a particle size of 1.0 mm to 2.0 mm. The ultrafiltration system is upgraded to a two-stage series system, with the first stage having a pore size of 0.2 μm and the second stage 0.1 μm, increasing the overall removal efficiency to 99.99%. Step 4 involves spraying a polytetrafluoroethylene (PTFE) coating onto the inner wall of the distillation column to further reduce surface energy and decrease the adhesion of high-boiling-point substances. Step 5 involves adding a machine learning module to the central controller to predict impurity trends based on historical data and intervene proactively. The final product achieves a total metal ion content of 0.05 ppb and a particulate matter concentration of 6 particles / mL, meeting the more stringent cooling requirements of EUV lithography. This solution demonstrates the scalability and technical adaptability of the invention in scenarios with extreme purity requirements.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0047] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-quality electronic fluorinated liquid, characterized in that, Includes the following steps: Step 1: Select perfluoro-2-methyl-3-oxahexane or its homologue with a branched structure as the main raw material. The general molecular formula of the main raw material is CnF2n+2O, where n is an integer from 6 to 12, the boiling range is from 85°C to 115°C, the initial purity is not less than 99.5 wt%, and the branched structure contains at least one trifluoromethyl side chain. Step 2: The main raw material and hydrogen fluoride are subjected to liquid-phase catalytic fluorination reaction for 2 to 4 hours under the action of a supported Lewis acid catalyst at 40°C to 70°C and 0.3 MPa to 0.6 MPa to generate crude fluorinated liquid. The supported Lewis acid catalyst is a boron trifluoride complex supported on a porous silica support. Step 3: The crude fluorinated liquid is subjected to a multi-stage gradient purification process, including molecular sieve adsorption dehydration, chelation resin removal of metal ions, and ultrafiltration membrane filtration of particulate matter. Step 4: The purified material is introduced into a high vacuum distillation column and distilled under the conditions of absolute pressure below 10 Pa, column bottom temperature of 120°C to 150°C, and reflux ratio of 5:1 to 10:

1. The fraction with boiling range concentrated between 98°C and 102°C is collected. Step 5: Install an online moisture analyzer, an inductively coupled plasma mass spectrometer, and a laser particle counter at the distillation outlet to monitor the concentrations of moisture, metal ions, and particulate matter in real time, and feed the monitoring data back to the central controller to dynamically adjust the operating parameters of the purification unit and the distillation operation conditions to obtain electronic fluorinated liquid that meets the ultra-high purity index.

2. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The main raw material has a kinematic viscosity of 0.8 mm² / s to 1.2 mm² / s at 25°C and a surface tension of 14 mN / m to 16 mN / m. The raw material storage tank is made of 316L stainless steel, with the inner wall electrolytically polished to a surface roughness Ra≤0.4μm. It is also sealed with nitrogen gas for protection, and the oxygen content of the system is controlled below 1 ppm.

3. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The supported Lewis acid catalyst has a support surface area of ​​300 m² / g to 500 m² / g and a pore size distribution of 8 nm to 15 nm. The catalyst loading is 1.5 wt% to 3.0 wt% of the total mass of the reactants. After the reaction, it is recovered by magnetic separation or filtration. The catalytic activity retention rate is not less than 95% after a single cycle.

4. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The molecular sieve adsorption uses type 3A or 4A molecular sieves with a particle size of 1.6 mm to 2.5 mm, a bed height of 800 mm to 1200 mm, an operating space velocity of 2 BV / h to 5 BV / h, and the moisture content after treatment is reduced to below 0.5 ppm.

5. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The chelating resin is an iminodiacetic acid type or mercapto-functionalized polystyrene resin with an exchange capacity of not less than 2.0 mmol / g and a bed height of 600 mm to 1000 mm. The total metal ion concentration is reduced to below 0.05 ppb at a flow rate of 3 BV / h. An acid-base elution and regeneration procedure is performed after processing 500 kg of material.

6. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The ultrafiltration membrane is a polytetrafluoroethylene hollow fiber membrane with a pore size of 0.1 μm, an operating pressure of 0.15 MPa to 0.25 MPa, a flow rate of 1.5 L / min to 2.5 L / min, and adopts a cross-flow filtration mode to reduce the concentration of particulate matter with a particle size ≥ 0.2 μm to below 5 particles / mL.

7. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The high-vacuum distillation column is an all-metal sealed structure. The column body is made of 316L stainless steel, and the inner wall is electrolytically polished with a surface roughness Ra≤0.2μm. The number of trays is 20 to 30, and the theoretical tray efficiency is not less than 90%. High-purity nitrogen is introduced as a protective atmosphere during the distillation process, and the oxygen content of the system is controlled below 0.5ppm.

8. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The online moisture analyzer is based on the cold mirror dew point method and has a detection limit of 0.1 ppm. The inductively coupled plasma mass spectrometer is equipped with a collision reaction cell and can simultaneously monitor multiple metal elements, with detection limits for each element below 0.01 ppb. The laser particle counter has a sampling flow rate of 100 mL / min, a particle size detection range of 0.1 μm to 5.0 μm, and a resolution of 0.01 μm.

9. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, The central controller dynamically adjusts operating parameters based on real-time monitoring data: when the moisture concentration exceeds 0.8 ppm, the molecular sieve regeneration frequency is increased; when the total metal ion concentration exceeds 0.08 ppb, the chelating resin regeneration cycle is shortened; when the particulate matter concentration exceeds 8 particles / mL, the ultrafiltration membrane flow rate is reduced and backwashing is initiated; when the fraction purity fluctuates, the reflux ratio or the bottom temperature of the column is finely adjusted.

10. The method for preparing high-quality electronic fluorinated liquid according to claim 1, characterized in that, After undergoing accelerated aging testing at 85℃ and 85%RH for 168 hours, the final product exhibits a moisture content change of no more than 0.1 ppm, a metal ion increase of no more than 0.01 ppb, and a particulate matter concentration fluctuation of no more than 2 particles / mL. Furthermore, the final product meets the following requirements: moisture content ≤ 1 ppm, total metal ion content ≤ 0.1 ppb, particulate matter concentration ≤ 10 particles / mL (particle size ≥ 0.2 μm), dielectric strength ≥ 30 kV / mm, and volume resistivity ≥ 1 × 10¹. 5 The requirements are Ω·cm and thermal conductivity ≥0.07W / m·K.

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