A device for continuously preparing phosphorus trifluoride based on liquid-liquid microfluidics

Abstract

The utility model belongs to fluorine chemical material preparation device technical field, concretely relates to a device of continuous preparation of phosphorus trifluoride based on liquid -liquid microfluidic, the device includes the mixer, spiral pipe micro -reactor and gas -liquid separation tank that communicate in proper order, the mixer is Y type mixer, and one feed port of Y type mixer is connected through pipeline with PCl3 storage jar, and the other feed port sets up liquid drop injection device and is connected through pipeline with AHF storage jar, and the discharge port of Y type mixer is connected to spiral pipe micro -reactor, the liquid material export of gas -liquid separation tank is connected through circulating pump and pipeline to spiral pipe micro -reactor, the device of the utility model can realize the efficient, safe, continuous preparation of phosphorus trifluoride through the connection combination of specific mixer and spiral pipe micro -reactor and gas -liquid separation tank.

Description

Technical Field

[0001] This utility model belongs to the technical field of fluorochemical material preparation device, specifically relating to a device for the continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics. Background Technology

[0002] Phosphorus trifluoride (PF3) is an important inorganic compound widely used in the electronics industry, chemical synthesis, and materials science. Currently, it is mainly synthesized through chemical reactions.

[0003] Existing methods for preparing phosphorus trifluoride mainly include the reaction of phosphorus trichloride with anhydrous hydrofluoric acid, the direct reaction of fluorine gas with phosphorus, the reaction of fluoride salts (such as zinc fluoride, ammonium fluoride, sodium fluoride, potassium fluoride, etc.) with phosphoric acid, and the reaction of phosphoric acid with hydrofluoric acid. Each of these methods has its own characteristics, among which the reaction of phosphorus trichloride (PCl3) with anhydrous hydrofluoric acid (AHF) to produce PF3 is a relatively feasible approach. This method has advantages such as relatively mild reaction conditions, readily available raw materials, and a mature process. It can be carried out at relatively low temperatures, reducing equipment requirements, and both phosphorus trichloride and anhydrous hydrofluoric acid are common chemical raw materials that are easy to obtain.

[0004] However, existing technologies also have many shortcomings. For example, the reaction involves highly corrosive substances (such as HF), placing extremely high demands on equipment and the operating environment, increasing equipment costs and maintenance difficulties. Furthermore, the reaction easily generates mono- and di-substituted intermediates (such as PCl2F and PClF2), increasing the difficulty and cost of product purification. Additionally, the reaction is highly exothermic, making it difficult to effectively control the reaction temperature within a low range, potentially leading to localized overheating and affecting product quality and yield. Moreover, to drive the reaction, excessive HF is usually required, which not only increases raw material costs but also introduces complexity in subsequent processing and potential environmental pollution risks. Simultaneously, the generated HCl and unreacted HF are highly corrosive and toxic, and the high pressure of the reaction products poses potential risks to operators and the environment, limiting its large-scale industrial application. Conventional tubular reactors / microchannel reactors are typically considered for completing the fluorination reaction at low doses to reduce reaction safety risks. However, under high gas-liquid ratio conditions, there are serious issues such as uneven liquid residence time and poor mass transfer efficiency. Meanwhile, the reaction itself generates a large amount of gas (such as PF3 and HCl), which seriously affects the flow and mass transfer of the liquid, leading to gas embolism and reducing the efficiency of the mixing reaction.

[0005] In summary, although existing technologies have made some progress in the preparation of phosphorus trifluoride, many problems still need to be solved, especially in terms of precise reaction control, by-product suppression, safety improvement, and enhanced mass transfer in high gas-liquid ratio reactions. Therefore, developing an efficient, safe, environmentally friendly, and economical phosphorus trifluoride preparation apparatus is of significant practical importance. Utility Model Content

[0006] In view of the shortcomings and deficiencies of the existing technology, the purpose of this utility model is to provide a device for the continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics.

[0007] This invention utilizes a specific Y-type mixer with a droplet injection device at the AHF inlet. This breaks AHF into spherical droplets, which then mix with liquid PCl3 for a reaction. This significantly increases the specific surface area and reaction contact area, promoting rapid reaction. It also reduces direct contact between AHF and the equipment, lowering the risk of corrosion, extending equipment lifespan, and improving operational safety. The use of a spiral tube microreactor further enhances mixing efficiency and reduces reaction safety risks. A gas-liquid separator rapidly separates the target product PF3 from the liquid PCl3 circulating reaction feedstock and heat transfer medium, while simultaneously removing heat generated during the reaction. Connecting the liquid material outlet of the gas-liquid separator to the spiral tube microreactor via a circulating pump and pipeline enables the recycling of excess liquid PCl3 feedstock, improving feedstock utilization and achieving continuous PF3 production.

[0008] The objective of this invention is achieved through the following technical solution: an apparatus for the continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics, comprising a mixer, a helical tube microreactor, and a gas-liquid separator connected in sequence; the mixer is a Y-type mixer, one inlet of which is connected to a phosphorus trichloride (PCl3) storage tank via a pipeline, and the other inlet is equipped with a droplet injection device and connected to an anhydrous hydrofluoric acid (AHF) storage tank via a pipeline; the outlet of the Y-type mixer is connected to the helical tube microreactor; the liquid material outlet of the gas-liquid separator is connected to the helical tube microreactor via a circulating pump and a pipeline.

[0009] This invention, by setting up a Y-type mixer and a droplet injection device at the feed inlet connected to the AHF storage tank, can achieve good dispersion and mixing of AHF feed into spherical droplets with PCl3, which can significantly increase the specific surface area and reaction contact area, promote rapid reaction, and reduce the direct contact of AHF with the equipment, thereby reducing the risk of equipment corrosion, extending the service life of the equipment, and improving operational safety.

[0010] Furthermore, the droplet ejection device can employ a pressure oscillating nozzle. The pressure oscillating nozzle is a commercially available droplet ejection device. It utilizes a self-excited oscillation chamber principle, using a geometric structure to induce fluid breakage into small spheres. External electronic components are used to assist in adjusting the inlet pressure. Its structural schematic diagram is shown below. Figure 2As shown. Specifically, the working principle of the pressure oscillating nozzle in this invention is as follows: AHF fluid from the AHF storage tank enters the pressure oscillating nozzle. After being accelerated by the contraction nozzle 2 (e.g., a contraction angle of 30° to 45°), the fluid forms a high-speed jet. When it enters the expansion chamber 3 (expansion ratio 1.5 to 2.0), the fluid shear layer generates natural vortices due to the velocity gradient. The jet impacts the downstream arc-shaped reflector wall 4, generating pressure disturbance waves that propagate upstream. The continuous fluid is transformed into a high-frequency pulsed flow within the device, with the instantaneous impact force increasing to 1.5 to 2.5 times that of the continuous jet, causing the liquid to undergo periodic stretching and compression. The liquid filament breaks into uniform small balls in the feed section 5 and enters the Y-type mixer. The frequency is monitored by an external piezoelectric sensor feedback circuit 6, and the inlet pressure is controlled and adjusted by a PID solenoid valve 1 to stabilize the oscillation. Using this in this invention has the advantages of precise and controllable feed speed and frequency.

[0011] Furthermore, metering pumps are installed on the pipes connecting the PCl3 storage tank and the Y-type mixer, as well as on the pipes connecting the AHF storage tank and the Y-type mixer. Metering pumps allow for convenient control of the feed ratio of AHF and PCl3. For example, if the feed molar ratio of AHF to PCl3 is controlled within the range of 1:3 to 10, excess PCl3 is used to dissolve the PF3 and HCl gaseous products generated during the reaction under high pressure. The resulting mixture can maintain a liquid phase state under relatively low pressure (the vapor pressure of PCl3 at the reaction temperature is less than 0.5 MPa, and the mixed vapor pressure after dissolving HCl and PF3 under these conditions is less than 1.0 MPa to 2.5 MPa). (If excess PCl3 is lacking as a dissolving medium, the vapor pressure of HCl and PF3 in the gas phase is high, requiring a pressure of over 6 MPa to make the resulting mixture liquid). This avoids the damage of the fluid structure to the gaseous products, solves the problem of uneven liquid residence time, and effectively improves reaction efficiency.

[0012] Furthermore, the channel diameter of the helical tube microreactor is 6–25 mm, and the length is 5–100 m. The helical tube microreactor is a commonly used reaction device in the field. Its structure consists of a helical fluid channel that advances forward during fluid flow, achieving both plug flow and ensuring spatial uniformity of the reaction, while also enhancing mixing and heat exchange to a certain extent. The dimensions of the helical tube microreactor can be adjusted according to actual production needs.

[0013] Furthermore, the helical microreactor is internally connected to a back pressure system. This back pressure system allows for convenient control of the reaction pressure within the helical microreactor. For example, controlling the pressure within the helical microreactor to 1.0 MPa–2.5 MPa, preferably 1.5 MPa–2.5 MPa, combined with an excess of PCl3 liquid material medium, ensures that the reactant AHF and reaction products PF3 and HCl remain in a liquid state after dissolving in PCl3. This improves the mixing effect of the reactants while preventing the gaseous products from damaging the fluid structure, solving the problem of uneven liquid residence time and effectively improving reaction efficiency. On the other hand, it effectively promotes the conversion of PF3 and reduces the formation of byproducts, improving reaction efficiency and product purity. Furthermore, it significantly reduces direct contact between highly corrosive gases (such as HF and HCl) and the equipment, thus reducing the risk of equipment corrosion. This design ensures the uniformity and stability of the reaction, further improving product quality, while also extending the equipment's service life and improving operational safety. Excessively low pressure can cause the gaseous components of the reaction to not completely dissolve in the liquid phase, reducing mass transfer efficiency.

[0014] Furthermore, a heating jacket is provided on the outside of the helical tube microreactor. The heating jacket allows for convenient control of the reaction temperature within the helical tube microreactor. For example, controlling the reaction temperature within the helical tube microreactor to 60–140°C, preferably 60–130°C, can promote the displacement reaction between PCl3 and AHF at higher temperatures, increasing the conversion rate of the target product PF3 and improving reaction efficiency. Simultaneously, it allows for better utilization of the exothermic reaction between PCl3 and AHF, and better temperature stability control when using excess PCl3 liquid material as the heat transfer medium. However, excessively high temperatures can lead to incomplete dissolution of the gaseous components in the liquid phase, reducing mass transfer efficiency.

[0015] Furthermore, the gas phase material outlet of the gas-liquid separator is further connected to a compression cooling device and a distillation separation device.

[0016] The gas-liquid separator can reduce the pressure to 0.5–1 MPa via a pressure valve to rapidly separate PF3 and HCl gases, while simultaneously removing the heat generated by the reaction. This design not only stabilizes the system temperature but also reduces additional cooling requirements and lowers energy consumption. The separated cryogenic liquid material (mainly excess unreacted PCl3 liquid and a small amount of low-substituted products) is re-entered into the helical microreactor via a circulating pump and pipeline to participate in the reaction until it leaves as PF3 gas. This energy recovery and recycling design further reduces system energy consumption, improves raw material utilization, reduces waste, and lowers production costs.

[0017] The compression cooling device and the distillation separation device are used to pressurize the gas phase components to 3.5 to 4.2 MPa and cool them to -30 to -2°C, so that PF3 is liquefied and then separated by distillation.

[0018] The method for continuously preparing phosphorus trifluoride using the apparatus of this invention is as follows:

[0019] (1) Pressure regulation: Nitrogen gas is introduced through the back pressure system to increase the pressure inside the spiral tube microreactor to 1.0 MPa to 2.5 MPa;

[0020] (2) Temperature control: The temperature of the spiral tube microreactor is raised to 60-140℃ by heating the jacket;

[0021] (3) Feeding and reaction: The PCl3 liquid in the PCl3 storage tank is transported to the mixer through one of the feed ports of the Y-type mixer. At the same time, the AHF liquid in the AHF storage tank is transported to the droplet injection device to break up and generate AHF spherical droplets, which enter the mixer. The PCl3 liquid and the AHF spherical droplets are axially mixed in the mixer. The feed molar ratio of AHF to PCl3 is controlled by the metering pump to be 1:3 to 10 before entering the spiral tube microreactor for reaction.

[0022] (4) Separation: The material from the outlet of the spiral tube microreactor enters the gas-liquid separator for depressurization and gas-liquid separation. The obtained gas phase components (mainly including PF3, HCl and a small amount of PCl2F and PClF2 byproducts) are pressurized and cooled by the compression cooling device to liquefy PF3 and then enter the distillation separation device for distillation separation and purification to obtain phosphorus trifluoride. The remaining liquid material enters the spiral tube microreactor through the circulation pump as PCl3 liquid feed to participate in the reaction.

[0023] Compared with the prior art, the beneficial effects of this utility model are:

[0024] (1) High efficiency of mass transfer and reaction: The device of this invention mixes AHF raw materials in the form of spherical droplets through a droplet jetting device, which can significantly improve the mixing effect of the raw materials and effectively improve the mass transfer effect and reaction efficiency.

[0025] (2) Enhanced safety: This utility model uses a droplet spraying device to break up AHF spherical droplets and evenly disperse them in liquid PCl3 for mixing and reaction, which significantly reduces the direct contact of highly corrosive AHF gas with the equipment, thereby reducing the risk of equipment corrosion, extending the service life of the equipment and improving operational safety.

[0026] (3) Energy Coupling and Energy Saving: After the reaction, the mixture passes through a gas-liquid separator to quickly separate PF3 and HCl gases, while simultaneously removing the heat generated by the reaction. This design not only stabilizes the system temperature but also reduces additional cooling requirements and lowers energy consumption. The separated cryogenic liquid material is re-entered into the helical tube microreactor via a circulating pump to participate in the reaction until it leaves as PF3 gas, further reducing system energy consumption. This energy recovery and recycling design significantly improves energy efficiency and reduces production costs. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the connection relationship of an apparatus for the continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics in an embodiment of this utility model.

[0028] Figure 2 This is a schematic diagram of the pressure oscillation nozzle used in this utility model. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0030] Example 1

[0031] A device for the continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics is shown in the schematic diagram below. Figure 1 As shown, the system includes a mixer 6, a spiral tube microreactor 7, a gas-liquid separator 8, and a back pressure system 9 connected in sequence. The mixer 6 is a Y-type mixer, with one inlet connected to a phosphorus trichloride (PCl3) storage tank 1 via a pipeline, and the other inlet equipped with a pressure oscillating nozzle 5 connected to an anhydrous hydrofluoric acid (AHF) storage tank 2 via a pipeline. A metering pump 4 is installed on the pipeline connecting the PCl3 storage tank 1 and the mixer 6, and a metering pump 3 is installed on the pipeline connecting the AHF storage tank 2 and the mixer 6. The outlet of the Y-type mixer is connected to the spiral tube microreactor 7, which has a channel diameter of 20 mm and a length of 25 m, and is equipped with a heating jacket. The liquid material outlet of the gas-liquid separator 8 is connected to the spiral tube microreactor 7 via a circulating pump 10 and a pipeline. The gas phase material outlet of the gas-liquid separator 8 is connected in sequence to a compressor 11, a cryostat 12, and a distillation column 13.

[0032] The method for continuously preparing phosphorus trifluoride based on the above-mentioned apparatus includes the following preparation steps:

[0033] (1) Pressure regulation: Nitrogen gas is introduced through the back pressure system 9 to increase the pressure inside the spiral tube microreactor 7 to 2MPa.

[0034] (2) Temperature control: The temperature inside the spiral tube microreactor 7 is raised to 80°C by heating the jacket.

[0035] (3) Feeding and reaction: The PCl3 liquid in the PCl3 storage tank 1 is transported to the mixer 6 through one of the feed ports of the Y-type mixer; at the same time, the AHF liquid in the AHF storage tank 2 is transported to the pressure oscillating nozzle 5 to break up and generate AHF spherical droplets with a size of 0.5±0.1μm, which enter the mixer 6. The PCl3 liquid and the AHF spherical droplets are axially mixed in the mixer 6. The feed molar ratio of AHF to PCl3 is controlled to be 1:6 by the metering pumps 3 and 4 to enter the spiral tube microreactor, forming a ring flow for reaction. The reaction residence time is controlled to be 3min by the material conveying flow rate.

[0036] (4) Separation: The material emanating from the spiral tube microreactor 7 is depressurized to 0.5 MPa through a pressure reducing valve and enters the gas-liquid separator 8 for gas-liquid separation. The resulting gas phase components (mainly including PF3, HCl, and small amounts of PCl2F and PClF2 byproducts) are compressed to 4.0 MPa by compressor 11, then cooled to -15°C by cryogenic cooler 12 to liquefy, and subsequently enter the distillation column 13 for distillation separation to obtain phosphorus trifluoride. The remaining liquid material in the gas-liquid separator 8 is at a temperature of 50°C and enters the spiral tube microreactor 7 through the circulation pump 10 as PCl3 liquid feed to participate in the reaction.

[0037] In this embodiment, the target product PF3 was tested and sampled at the outlet of the spiral tube microreactor 7 after cooling. The conversion rate of PF3 reached 99.87% (actual amount of PF3 produced / theoretical amount of PF3 produced; PF3 / PClF2 / / PCl2F were detected by GC-MS and separated using a weakly polar chromatographic column (such as DB-5MS)). The by-product formation rates were: PCl2F 0.02% (actual amount of PClF2 produced / theoretical amount of PF3 produced), PClF2 0.01% (actual amount of PCl2F produced / theoretical amount of PF3 produced).

[0038] Comparative Example 1

[0039] An apparatus for the continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics, compared with Example 1, omits a pressure oscillation nozzle 5 at the feed inlet of the Y-type mixer connected to the anhydrous hydrofluoric acid (AHF) storage tank 2. The AHF liquid feed is not broken into spherical droplets by the pressure oscillation nozzle; instead, it is directly mixed axially with PCl3 liquid in the mixer using continuous liquid feeding. The rest of the process remains the same.

[0040] The test results showed that the conversion rate of the target product PF3 in the effluent of the comparative spiral microreactor was 97.60%, and the by-product formation rates were: PCl2F 0.34% and PClF2 0.15%.

[0041] The results of this comparative example and Example 1 show that by setting a pressure oscillating nozzle to break the AHF liquid feed into spherical droplets for reaction, the present invention can significantly improve reaction efficiency and reduce the generation of by-products.

[0042] The above embodiments are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present utility model shall be considered equivalent substitutions and shall be included within the protection scope of the present utility model.

Claims

1. A device for continuous production of phosphorus trifluoride based on liquid-liquid microfluidics, characterized in that: It includes a mixer, a spiral tube microreactor, and a gas-liquid separator connected in sequence; the mixer is a Y-type mixer, one inlet of which is connected to the PCl3 storage tank via a pipeline, and the other inlet is equipped with a droplet injection device and connected to the AHF storage tank via a pipeline; the outlet of the Y-type mixer is connected to the spiral tube microreactor; the liquid material outlet of the gas-liquid separator is connected to the spiral tube microreactor via a circulation pump and a pipeline. 2.The device for continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics according to claim 1, characterized in that: The droplet ejection device is a pressure oscillating nozzle. 3.The device for continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics according to claim 1, characterized in that: Metering pumps are installed on the pipeline connecting the PCl3 storage tank and the Y-type mixer, as well as on the pipeline connecting the AHF storage tank and the Y-type mixer. 4.The device for continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics according to claim 1, characterized in that: The channel diameter of the spiral tube microreactor is 6–25 mm, and the length is 5–100 m.

5. The device for continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics according to claim 1, characterized in that: The spiral tube microreactor is internally connected to a back pressure system.

6. The device for continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics according to claim 1, characterized in that: The spiral tube microreactor is equipped with a heating jacket on its exterior. 7.The device for continuous preparation of phosphorus trifluoride based on liquid-liquid microfluidics according to claim 1, characterized in that: The gas phase material outlet of the gas-liquid separator is further connected to a compression cooling device and a distillation separation device.

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