An apparatus for the production of perfluorobutanes

Abstract

A device for preparing perfluorobutane, comprising a mixing kettle, the mixing kettle is provided with a feeding port, the outlet at the bottom of the mixing kettle is connected with the first inlet at the top of an electrolytic fluorination tank, the electrolytic fluorination tank is provided with a polar plate group and a stirring system, the gas outlet at the top of the electrolytic fluorination tank is connected with the inlet of a vertical tube condenser, the liquid outlet at one side of the vertical tube condenser is connected with the second inlet at the top of the electrolytic fluorination tank, the gas outlet at the top of the vertical tube condenser is connected with the inlet of a buffer tank, the outlet of the buffer tank is connected with a tail gas purification device, the tail gas purification device is connected with a physical adsorption device, the physical adsorption device is connected with a low-temperature collection device; further comprising a PLC control device. The device can significantly improve the electrolysis efficiency, effectively inhibit the side reaction, improve the product purity and yield, and realize the stable controllability and good repeatability of the production process under the real-time monitoring and automatic adjustment of the PLC device.

Description

Technical Field

[0001] This utility model belongs to the field of chemical engineering technology, specifically relating to an apparatus for preparing perfluorobutane. Background Technology

[0002] Perfluorobutane (PFR) is a typical perfluorocarbon (PFC), a high-density, low-boiling-point inert gas. Its physical properties are determined by its highly symmetrical molecular structure and strong carbon-fluorine bonds. It is a colorless, odorless, and non-toxic gas with exceptionally high solubility for non-polar gases such as oxygen and carbon dioxide. It also possesses low viscosity, low surface tension, and excellent chemical and thermal stability. Its main applications include cleaning and etching agents in the electronics industry, imaging agents in the medical field, coolants and cooling media for refrigeration and heat transfer, and fire extinguishing agents.

[0003] Currently, the equipment for preparing perfluorobutane includes traditional electrolytic fluorination equipment and batch fluorination reaction equipment.

[0004] Traditional electrochemical fluorination devices for preparing perfluorobutane are limited by the structural design of the electrolytic fluorination tank, the selection of vessel and electrode materials, and insufficient automation control, such as the design of electrode spacing, the selection of electrode materials, and imprecise PLC control. Insufficient control precision during traditional electrolytic fluorination easily leads to fluctuations in operating conditions, resulting in increased byproducts and low electrolysis efficiency. Due to structural and control limitations, the reaction process is non-selective, often accompanied by various side reactions. These side reactions cause carbon chain breakage, skeletal rearrangement, intermolecular polymerization, and carbonization, generating a series of byproducts, including low-molecular-weight perfluoroalkanes, perfluorocyclic ethers, and high-molecular-weight fluorocarbons. These byproducts have similar physicochemical properties to the target product, perfluorobutane, forming complex azeotropic systems or closely spaced boiling point systems, making subsequent separation and purification extremely difficult, ultimately significantly reducing the yield and purity of perfluorobutane.

[0005] The primary drawback of using a batch reactor for the preparation of perfluorobutane is poor atom economy. The theoretical ratio of chlorobutane to fluorine is 1:10, resulting in large quantities of fluorine and nitrogen, which raises safety and selection challenges. Furthermore, due to the limited space within the reactor, excess fluorine is unevenly dispersed, and combined with intense concentrated exothermic reactions, this easily leads to localized over-fluorination and carbon chain breakage, resulting in complex byproduct composition and reduced yield and purity of the target product. In addition, the highly reactive fluorine gas in a batch reactor introduces strong corrosiveness and exothermic runaway risks, making process control difficult and reproducible. Ultimately, these drawbacks of the batch reactor collectively contribute to the poor production efficiency and economics of this process. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this invention proposes an apparatus for preparing perfluorobutane. Its core lies in the integration of a continuous production line consisting of a novel electrolytic fluorination cell, a vertical tubular condenser, product purification and collection equipment, and PLC control equipment. This apparatus not only significantly improves electrolysis efficiency and effectively suppresses side reactions, but also precisely monitors and automatically adjusts parameters such as temperature, pressure, current, voltage, and cumulative ampere-hours throughout the entire apparatus in real time. This results in improved product purity and yield while achieving stable, controllable, and highly repeatable production processes. This apparatus successfully overcomes the inherent defects of traditional electrolytic fluorination equipment, providing a novel solution for the large-scale, low-cost production of perfluorobutane, with broad application prospects.

[0007] Under the precise control of a PLC system, the gas mixture (containing perfluorobutane, hydrogen, chlorine, and HF) generated in the novel electrolytic fluorination tank first enters a vertical tube condenser to remove most of the HF; then it passes through a tail gas purification device to remove trace amounts of acidic compounds; subsequently, it undergoes deep drying through a physical adsorption device; finally, the gas is collected and purified through a specially structured collection device.

[0008] The purpose of this utility model is achieved through the following technical solution: an apparatus for preparing perfluorobutane, comprising a mixing vessel, a feeding port, an outlet at the bottom of the mixing vessel connected to a first inlet at the top of an electrolytic fluorination cell, the electrolytic fluorination cell being provided with an electrode plate assembly and a stirring system, a gas outlet at the top of the electrolytic fluorination cell connected to the inlet of a vertical tube condenser, a liquid outlet on one side of the vertical tube condenser connected to a second inlet at the top of the electrolytic fluorination cell, a gas outlet at the top of the vertical tube condenser connected to the inlet of a buffer tank, an outlet of the buffer tank connected to a tail gas purification device, a tail gas purification device connected to a physical adsorption device, and a physical adsorption device connected to a low-temperature collection device; the apparatus also includes a PLC control device, which is electrically connected to thermometers installed in the mixing vessel, the electrolytic fluorination cell, and the vertical tube condenser, and is also electrically connected to pressure transmitters installed in the mixing vessel and the electrolytic fluorination cell.

[0009] Furthermore, the cryogenic collection equipment is also connected to the venting pipeline.

[0010] Furthermore, the exhaust gas purification equipment includes a first wet absorption tank, a second wet absorption tank, and a third wet absorption tank connected in series, and the physical adsorption equipment includes a first dry adsorption tank and a second dry adsorption tank connected in series.

[0011] Furthermore, the cryogenic collection device includes a refrigerant tank, inside which is a collection tank and a coil coiled around the outside of the collection tank. The upper end of the coil is connected to a second dry adsorption tank, and the lower end of the coil extends into the bottom of the collection tank. The outlet of the collection tank is connected to a venting pipeline.

[0012] Furthermore, the volume ratio of the coil inside the tube to the volume of the collection tank is 1:1 to 2:1.

[0013] Furthermore, the electrode assembly and stirring system include organic matter located in the electrolytic fluorination tank, and several circular electrode plates for electrolyzing the organic matter. The several circular electrode plates include a cathode plate and an anode plate, which are arranged in sequence at intervals and connected to a cathode rod and an anode rod, respectively. The system also includes a frame stirrer installed in the electrolytic fluorination tank. A through hole is provided at the center of the circular electrode plate, and the frame stirrer extends into the through hole of the stacked circular electrode plates.

[0014] Furthermore, the cathode rod and anode rod are electrically connected to a DC power supply, which in turn is electrically connected to a PLC control device via a 485 communication interface.

[0015] Furthermore, the material outlet at the bottom of the electrolytic fluorination tank is connected to the inlet of the mixing vessel to prevent abnormal phenomena from occurring in the electrolytic fluorination tank.

[0016] Furthermore, the coil is a stainless steel flexible coil, ensuring that the condensate in the coil flows smoothly into the collection tank.

[0017] The first wet adsorption tank contains a sodium thiosulfate or sodium iodide solution. The second and third wet adsorption tanks use a 10%–30% KOH alkaline solution, i.e., a KOH aqueous solution with a mass fraction of 10%–30%. The first and second dry adsorption tanks both use an adsorbent with a pore size of 0.3 nm (3 Å).

[0018] Among them, the new electrolytic fluorination cell adopts a combination of circular electrodes and magnetic stirring. On the one hand, it ensures efficient mixing of raw materials and hydrogen fluoride during electrolysis to improve electrolysis efficiency; on the other hand, the circular electrodes guide the gaseous products to quickly leave the central area, minimizing secondary reactions of the products and thus effectively suppressing product breakage, rearrangement, polymerization, and carbonization.

[0019] The vertical tube condenser promptly discharges perfluorobutane gas, hydrogen, and chlorine, while simultaneously returning HF to the electrolytic fluorination tank, thus achieving material recycling and improving process efficiency.

[0020] The exhaust gas purification equipment aims to remove impurity gases from the target product in stages, such as chlorine, HF, and intermediate fluorine-containing impurities. The first-stage absorption device uses sodium thiosulfate or sodium iodide solution to specifically remove chlorine. The second and third absorption devices use 10% to 30% KOH alkaline solution to deeply absorb HF and fluorine-containing gases.

[0021] The target product is deeply dried using a physical adsorption device, and water molecules and residual fluorine-containing impurity gases are selectively adsorbed using an adsorbent with a pore size of 0.3 nm (3A). At the same time, this pore size ensures that perfluorobutane (approximately 0.63 nm), which has a larger dynamic diameter, is not adsorbed and can pass through smoothly.

[0022] A cryogenic collection device is formed by connecting a flexible stainless steel coil in series with a collection tank, with a volume ratio of 1:1 to 2:1 between the flexible stainless steel coil and the collection tank. This design ensures that the gas can be fully cooled into liquid and that the condensed liquid can flow back smoothly into the collection tank.

[0023] The PLC control equipment collects temperature and pressure signals from the electrolytic fluorination tank, mixing vessel, and vertical tube condenser via cables, and controls the corresponding solenoid valves for automatic adjustment. The PLC control equipment connects to pressure transmitters in the mixing vessel and electrolytic fluorination tank via cables to monitor and control the equipment pressure in real time. The PLC control equipment exchanges data with the DC power supply via a 485 communication interface, not only monitoring and adjusting the current and voltage of the electrolytic fluorination tank in real time, but also recording and storing accumulated ampere-hour data.

[0024] The PLC control equipment ensures that the electrolysis process is within the optimal process window by performing high-precision real-time monitoring and automatic adjustment of key parameters such as temperature, pressure, current, voltage, and cumulative ampere-hours. This stable and controllable environment significantly suppresses side reactions such as carbon chain breakage and over-fluorination, thereby fundamentally improving reaction selectivity and current efficiency.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) This device improves the electrolysis efficiency of preparing perfluorobutane from chlorobutane and effectively suppresses side reactions, thereby improving product purity and yield while achieving stable and controllable production process with good repeatability.

[0027] (2) The device adopts a new type of electrolytic fluorination cell and vertical tube condenser to ensure timely gas discharge and material recycling, improve the yield of target product, and inhibit the breakage, rearrangement, polymerization and carbonization of target product.

[0028] (3) The device uses a coil and a collection tank in series to ensure that the gas is fully purified and easy to liquefy and collect, thus improving the product yield.

[0029] (4) The device uses PLC equipment to monitor and automatically adjust various parameters in real time, ensuring the stability and controllability of the electrolysis process. At the same time, it suppresses phenomena such as carbon chain breakage and excessive fluorination.

[0030] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more obvious and understandable, preferred embodiments are given below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is a top view schematic diagram of the circular electrode plate structure of the electrolytic fluorination cell electrode plate group in the apparatus for preparing perfluorobutane according to this utility model;

[0032] Figure 2 This is a schematic diagram of the circular electrode assembly structure in an apparatus for preparing perfluorobutane according to this utility model;

[0033] Figure 3 This is a schematic diagram of the combined structure of the circular electrode assembly and the frame stirrer in an apparatus for preparing perfluorobutane according to this utility model.

[0034] Figure 4 This is a schematic diagram of the electrolytic fluorination tank structure in an apparatus for preparing perfluorobutane according to this utility model.

[0035] Figure 5 This is a schematic diagram of the apparatus for preparing perfluorobutane according to the present invention.

[0036] Figure Labels

[0037] 1-Electrolytic fluorination tank, 2-Anode plate, 3-Cathode plate, 4-Cathode rod, 5-Anode rod, 6-Stirring blade, 7-Stirring shaft, 8-Magnetic actuator, 9-Flange cover, 10-Mixing vessel, 11-Vertical tube condenser, 12-Buffer tank, 13-First wet absorption tank, 14-Second wet absorption tank, 15-Third wet absorption tank, 16-First dry adsorption tank, 17-Second dry adsorption tank, 18-Collection equipment. Detailed Implementation

[0038] To further illustrate the technical means and effects adopted by this utility model to achieve its intended purpose, the following will describe in detail the specific implementation, structure, features and effects of an apparatus for preparing perfluorobutane according to this utility model, in conjunction with preferred embodiments and accompanying drawings.

[0039] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0040] Please combine Figure 5 An embodiment of an apparatus for preparing perfluorobutane includes a mixing vessel 10 with a feeding port. The outlet at the bottom of the mixing vessel 10 is connected to a first inlet at the top of an electrolytic fluorination tank 1. The electrolytic fluorination tank 1 is equipped with an electrode assembly and a stirring system. The material outlet at the bottom of the electrolytic fluorination tank 1 is connected to the inlet of the mixing vessel 10, used to transfer the HF solution obtained after the reaction to the mixing vessel 10 for recycling in case of an abnormality in the electrolytic fluorination tank. The gas outlet at the top of the electrolytic fluorination tank 1 is connected to the inlet of a vertical tube condenser 11. The liquid outlet on one side of the vertical tube condenser 11 is connected to a second inlet at the top of the electrolytic fluorination tank 1. The gas outlet at the top of the vertical tube condenser 11 is connected to the inlet of a buffer tank 12. Thus, the gas in the electrolytic fluorination tank 1 enters the vertical tube condenser 11, where the HF is condensed and returned to the electrolytic fluorination tank 1, while perfluorobutane gas, chlorine, and hydrogen gas enter the buffer tank 12.

[0041] The outlet of the buffer tank 12 is connected to the exhaust gas purification equipment, the exhaust gas purification equipment is connected to the physical adsorption equipment, the physical adsorption equipment is connected to the low temperature collection equipment 18, and the low temperature collection equipment 18 is also connected to the venting pipeline.

[0042] In this embodiment, the exhaust gas purification equipment includes a first wet absorption tank 13, a second wet absorption tank 14, and a third wet absorption tank 15 connected in series. The physical adsorption equipment includes a first dry adsorption tank 16 and a second dry adsorption tank 17 connected in series. Specifically, the outlet of the buffer tank 12 is connected to the inlet of the first wet absorption tank 13, the outlet of the first wet absorption tank 13 is connected to the inlet of the second wet absorption tank 14, the outlet of the second wet absorption tank 14 is connected to the inlet of the third wet absorption tank 15, the outlet of the third wet absorption tank 15 is connected to the inlet of the first dry adsorption tank 16, and the outlet of the first dry adsorption tank 16 is connected to the outlet of the second dry adsorption tank 17.

[0043] The first wet absorption tank 13 contains a sodium thiosulfate or sodium iodide solution. The second wet absorption tank 14 and the third wet absorption tank 15 use a 10%–30% KOH alkaline solution, i.e., a KOH aqueous solution with a mass fraction of 10%–30%. In this embodiment, a 20% KOH alkaline solution is used. The first dry adsorption tank 16 and the second dry adsorption tank 17 both use an adsorbent with a pore size of 0.3 nm (3 Å).

[0044] The low-temperature collection device 18 includes a refrigerant tank, inside which is a collection tank and an elastic stainless steel coil coiled around the outside of the collection tank. The upper end of the elastic stainless steel coil (in this embodiment, the upper end of the elastic stainless steel coil is also its starting end) is connected to the second dry adsorption tank 17, and the end of the coil extends into the bottom of the collection tank. The outlet of the collection tank is connected to the venting pipeline.

[0045] In this embodiment, the volume ratio of the coil to the collection tank is 1.5:1. In other embodiments, this volume ratio can also be other values ​​between 1:1 and 2:1.

[0046] Refrigerant is circulated into the refrigerant tank. Both the mixing vessel 10 and the electrolytic fluorination tank 1 are equipped with jackets, through which refrigerant is circulated.

[0047] The device also includes a PLC control unit, which is electrically connected to thermometers installed in the mixing tank 10, the electrolytic fluorination tank 1, and the vertical tube condenser 11, respectively. The PLC control unit is also electrically connected to pressure transmitters installed in the mixing tank 10 and the electrolytic fluorination tank 1, respectively.

[0048] Please combine Figure 1 , Figure 2The aforementioned electrode assembly and stirring system include organic matter located in the electrolytic fluorination tank 1, and several circular electrode plates for electrolyzing the organic matter. Each circular electrode plate includes an anode plate 2 and a cathode plate 3, which are arranged sequentially at equal intervals with a layer spacing of 1mm to 5mm, preferably 2mm to 4mm. The anode plate 2 and cathode plate 3, and the circular electrode plates and electrode rods, are all connected by bolts. The cathode plate 3 and anode plate 2 are respectively connected to cathode rod 5 and anode rod 4. The cathode rod 4 and anode rod 5 on the electrolytic fluorination tank 1 are both L-shaped, fixed to the flange cover 9, and insulated and sealed. The circular electrode group, formed by several circular electrodes, ensures that the current path length between the anode and cathode in the fluorination tank is approximately equal and the distance is minimized. Secondly, the current density released by the circular electrode group is relatively uniform, and the fluorination reaction rate and degree are roughly the same for both anode plates, reducing the formation of side reactions and over-fluorination products. Furthermore, the electrode wear during the reaction process is more uniform, avoiding localized hot spots or current concentrations that could lead to excessive corrosion of some plates, thus increasing the service life of the electrodes. In addition, circular electrodes are more suitable for industrial mass production, which improves production efficiency and provides operational advantages during use.

[0049] The cathode rod 5 and anode rod 4 are electrically connected to a DC power supply, which is then electrically connected to a PLC control device via a 485 communication interface.

[0050] The thickness of the circular electrode plate is 2-5 mm, preferably 2-3 mm. The spacing between the layers of the circular electrode plates is 1 mm-5 mm, preferably 2 mm-4 mm. The ratio of the inner diameter of the electrolytic fluorination tank 5 to the diameter of the circular electrode plate is 1.7:1 to 2:1; the ratio of the height of the circular electrode plate to the height of the inner diameter of the electrolytic fluorination tank 5 is 1:1.3 to 1:2. Electrode assemblies within this parameter range have advantages such as high current density, excellent electrolysis efficiency, high electrolysis efficiency, uniform fluorination, high product stability, and easy maintenance, effectively reducing operating costs.

[0051] For the aforementioned circular electrode plates, a through-hole can be provided at their center. The through-holes formed by the equidistant arrangement of multiple circular electrode plates create a receiving space. A frame-type stirrer is also installed inside the electrolytic fluorination tank 5. The stirring blades 6 and stirring shaft 7 of the frame-type stirrer extend into the through-holes of the stacked circular electrode plates, stirring the organic matter within the electrolytic fluorination tank 5. This ensures thorough mixing and directional circulation of the organic matter between the circular cathode plate 3 and anode plate 2. The frame-type stirrer is particularly suitable for applications requiring strict control of polymerization, coking, stacking, crystallization, and heating / cooling processes. Under the action of the frame-type stirrer, the solvent and organic raw materials are firstly thoroughly mixed, effectively eliminating problems such as uneven concentration, coking, wall adhesion, and deposition, thus ensuring the uniformity and efficiency of the electrolysis process. Secondly, under the directional circulation formed by the stirrer, the electrolysis products can be discharged from the electrode spacing in a timely manner, significantly reducing the occurrence of side reactions or excessive reactions, thereby improving electrolysis efficiency.

[0052] Please combine Figure 3 , Figure 4 The frame-type stirrer further includes a stirring shaft 7 and blades 6. The blades 6, mounted on the stirring shaft 7, are located at the through holes of the circular substrate assembly. The blades 6 are spaced at several intervals, and these intervals are connected by a connecting frame and arranged parallel and perpendicular to the stirring shaft 7 with the stirring shaft 7 as the center. The blades 6 are symmetrically arranged with the stirring shaft 7 as the center, which ensures uniform and stable stirring.

[0053] The frame-type stirrer is magnetically driven in a sealed state by a magnetic actuator 8 located at the top of the electrolytic fluorination tank. This magnetically driven sealing technology overcomes the shortcomings of dynamic sealing, ensuring the long-term stable and efficient operation of the electrolytic fluorination tank in harsh environments such as low temperature, low pressure, and hydrogen fluoride.

[0054] The ratio of the inner diameter of the circular electrode plate to the outer diameter of the frame-type agitator blade 6 is 4:5 to 1:2.

[0055] The ratio of the height of the circular electrode assembly to the height of the frame-type agitator blade 6 is 1:1 to 5:3.

[0056] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model's technical solution shall still fall within the scope of the present utility model's technical solution.

Claims

1. An apparatus for preparing perfluorobutane, characterized in that, The system includes a mixing vessel with a feeding port. The outlet at the bottom of the mixing vessel is connected to the first inlet at the top of the electrolytic fluorination tank. The electrolytic fluorination tank is equipped with an electrode plate assembly and a stirring system. The gas outlet at the top of the electrolytic fluorination tank is connected to the inlet of a vertical tube condenser. The liquid outlet on one side of the vertical tube condenser is connected to the second inlet at the top of the electrolytic fluorination tank. The gas outlet at the top of the vertical tube condenser is connected to the inlet of a buffer tank. The outlet of the buffer tank is connected to a tail gas purification device. The tail gas purification device is connected to a physical adsorption device. The physical adsorption device is connected to a low-temperature collection device. The system also includes a PLC control device, which is electrically connected to thermometers installed in the mixing vessel, the electrolytic fluorination tank, and the vertical tube condenser. The PLC control device is also electrically connected to pressure transmitters installed in the mixing vessel and the electrolytic fluorination tank.

2. The apparatus for preparing perfluorobutane as described in claim 1, characterized in that, The cryogenic collection equipment is also connected to the venting pipeline.

3. The apparatus for preparing perfluorobutane as described in claim 1, characterized in that, The exhaust gas purification equipment includes a first wet absorption tank, a second wet absorption tank, and a third wet absorption tank connected in series; the physical adsorption equipment includes a first dry adsorption tank and a second dry adsorption tank connected in series; the low-temperature collection equipment includes a refrigerant tank, inside which is a collection tank and a coil coiled outside the collection tank.

4. The apparatus for preparing perfluorobutane as described in claim 3, characterized in that, The upper end of the coil is connected to the second dry adsorption tank, and the lower end of the coil extends into the bottom of the collection tank. The outlet of the collection tank is connected to the venting pipeline.

5. The apparatus for preparing perfluorobutane as described in claim 3, characterized in that, The volume ratio of the coil to the collection tank is 1:1 to 2:

1.

6. The apparatus for preparing perfluorobutane as described in claim 1, characterized in that, The material outlet at the bottom of the electrolytic fluorination tank is connected to the inlet of the mixing vessel.

7. The apparatus for preparing perfluorobutane as described in claim 1, characterized in that, The electrode assembly and stirring system include organic matter located in an electrolytic fluorination tank, and several circular electrode plates for electrolyzing the organic matter. The several circular electrode plates include a cathode plate and an anode plate, which are arranged in sequence at intervals and connected to a cathode rod and an anode rod, respectively. The system also includes a frame stirrer installed in the electrolytic fluorination tank. A through hole is provided at the center of the circular electrode plate, and the frame stirrer extends into the through hole of the stacked circular electrode plates.

8. The apparatus for preparing perfluorobutane as described in claim 1, characterized in that, The coil is a stainless steel flexible coil.

9. The apparatus for preparing perfluorobutane as described in claim 7, characterized in that, The cathode rod and anode rod are electrically connected to a DC power supply, which in turn is electrically connected to a PLC control device via a 485 communication interface.

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