A preparation process of fluoroethylene carbonate

Abstract

The invention discloses a preparation process of fluoroethylene carbonate, comprising the following steps: S1: connecting a liquid inlet end of ethylene carbonate with a three-stage series reaction mechanism; S2: introducing a fluorine-nitrogen mixed gas and ethylene carbonate into the three-stage series reaction mechanism for reaction, and generating HF tail gas that flows into a hydrogen fluoride recovery pipe; S3: heating product hot water, and pumping the material into a deacidification kettle for deacidification; S4: subjecting the deacidified material to three-stage rectification to finally obtain a product; S5: merging the HF tail gas and introducing it into a three-stage series ethylene carbonate pre-reaction unit, connecting a storage tank storing ethylene carbonate into the ethylene carbonate pre-reaction unit for pre-reaction with the introduced tail gas HF, and introducing the pre-reacted ethylene carbonate into the liquid inlet end of ethylene carbonate to react with the fluorine-nitrogen mixed gas; S6: treating the tail gas discharged from the ethylene carbonate pre-reaction unit through a tail gas treatment device and then discharging it. The invention can greatly improve the fluorine gas conversion rate, and realize reaction conversion of the fluorine gas in a closed loop.

Description

Technical Field

[0001] The present invention relates to a preparation process of a chemical material, in particular to a preparation process of fluoroethylene carbonate. Background Art

[0002] Fluoroethylene carbonate (FEC) is an important fine chemical material, mainly used as a film-forming additive and explosion-proof solvent in lithium battery electrolytes. After adding fluoroethylene carbonate to the electrolyte, a solid electrolyte interface (SEI film) with excellent performance can be formed on the electrode. The film has a tight structure, which can reduce the impedance of the battery and effectively inhibit the decomposition of some electrolytes, thereby improving the battery's specific capacity, safety and life.

[0003] The production process of fluoroethylene carbonate involves a substitution reaction between liquid ethylene carbonate and a fluorine-nitrogen mixture (20% fluorine, 80% nitrogen). The primary reaction in the reactor is: C3H4O3 + F2 (20% fluorine, 80% nitrogen) → C3H3FO3 + HF. This reaction is accompanied by a side reaction: C3H3FO3 + 2F2 (20% fluorine, 80% nitrogen) → C3H2F203 + 2HF. This reaction involves the introduction of a fluorine-nitrogen mixture and the formation of hydrogen fluoride as a byproduct impurity. A large amount of this mixture is required to mix ethylene carbonate with the fluorine-nitrogen mixture. Furthermore, a large amount of HF tail gas is generated during the synthesis and deacidification of fluoroethylene carbonate. This HF tail gas is not only lost in large quantities but also requires high disposal costs. Therefore, the use of the fluorine-nitrogen mixture and the loss of HF tail gas have always been the cause of high production costs.

[0004] Therefore, this case aims to provide a preparation process for fluoroethylene carbonate, which can greatly improve the fluorine gas conversion rate. Fluorine gas is converted in a closed loop, overcoming the instability of the discharge components of the traditional intermittent method, and realizing the continuous addition of raw materials and the continuous discharge of reaction materials. The reaction discharge components are stable and very uniform. Summary of the Invention

[0005] The present invention provides a preparation process of fluoroethylene carbonate, which can effectively solve the above problems.

[0006] The present invention is achieved in that:

[0007] A process for preparing fluoroethylene carbonate comprises the following steps:

[0008] S1: connecting the liquid inlet of ethylene carbonate to a three-stage series reaction mechanism, and the three-stage series reaction mechanism is respectively connected to a hydrogen fluoride recovery pipe and a fluorine-nitrogen mixed gas distribution station;

[0009] S2: Ethylene carbonate is introduced into the three-stage series reaction mechanism, and the fluorine-nitrogen mixed gas is introduced into the three-stage series reaction mechanism through the fluorine-nitrogen mixed gas distribution table and the fluorine-nitrogen mixed gas inlet pipe. The generated material flows out to the semi-finished product receiving tank, and the generated HF tail gas flows into the hydrogen fluoride recovery pipe;

[0010] S3: The semi-finished product receiving tank is heated with hot water, and the material is pumped into the deacidification kettle, the deacidification kettle is heated, heated dry gas is introduced for purge, and the generated HF tail gas is blown into the hydrogen fluoride recovery pipe;

[0011] S4: The deacidified material is subjected to three-stage distillation using the different boiling points of the components to obtain the final product;

[0012] S5: The HF tail gas flowing in through the hydrogen fluoride recovery pipe is combined and introduced into the three-stage ethylene carbonate pre-reactor unit in series. The storage tank storing ethylene carbonate is connected to the ethylene carbonate pre-reactor unit to pre-react with the introduced tail gas HF. The pre-reacted ethylene carbonate is introduced into the ethylene carbonate liquid inlet to react with the fluorine-nitrogen mixed gas.

[0013] S6: The tail gas discharged from the ethylene carbonate pre-reaction unit is treated by the tail gas treatment device and then discharged.

[0014] As a further improvement, the S2 specifically includes:

[0015] S21: Ethylene carbonate is introduced into the first reaction tank to undergo a primary substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station;

[0016] S22: the material after the reaction in the first reaction tank flows into the second reaction tank and undergoes a secondary substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station;

[0017] S23: The material after the reaction in the second reaction tank flows into the third reaction tank and undergoes a three-stage substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station. The generated material flows from the third reaction tank into the semi-finished product receiving tank.

[0018] As a further improvement, the temperature of the deacidification kettle is 50-60°C.

[0019] As a further improvement, the S4 specifically includes:

[0020] S41: The deacidified material is continuously pumped into a low-boiling distillation tower to separate the light component impurities from the top of the tower and purify the bottom material;

[0021] S42: The bottom material of the first low-boiling distillation tower is pumped into the second low-boiling distillation tower to separate the light component impurities again;

[0022] S43: The bottom material of the secondary low-boiling distillation tower is pumped into a high-boiling distillation tower to separate the heavy component impurities, and finally the final product is extracted from the top of the high-boiling tower.

[0023] As a further improvement, the ethylene carbonate pre-reactor unit includes a third pre-reactor, a second pre-reactor, and a first pre-reactor. The combined exhaust gas flows through the third pre-reactor to the second pre-reactor and then to the first pre-reactor, and finally flows to the exhaust gas treatment device through the first pre-reactor. The storage tank for storing ethylene carbonate flows into the first pre-reactor, the second pre-reactor, and the third pre-reactor in turn to perform pre-reaction with the exhaust gas.

[0024] As a further improvement, the three-stage series reaction mechanism in S1 includes:

[0025] A three-stage reaction assembly, wherein a first output pipe is provided at the bottom of the first reaction tank body, the three-stage reaction assembly comprises a second reaction tank body connected to the first output pipe, a side of the second reaction tank body away from the first reaction tank body is connected to a third reaction tank body through a second output pipe, the second reaction tank body and the third reaction tank body are respectively connected to a fluorine-nitrogen mixed gas distribution table through a second fluorine-nitrogen mixed gas inlet pipe and a third fluorine-nitrogen mixed gas inlet pipe, and the second reaction tank body and the third reaction tank body are both connected to a hydrogen fluoride recovery pipe;

[0026] The mixed gas guide structure includes an air guide tube with a top slidably mounted inside the first fluorine-nitrogen mixed gas inlet pipe, a gas delivery plate disposed at the bottom of the air guide tube, a plurality of gas delivery holes being formed at the bottom of the gas delivery plate, an outer side of the gas delivery plate being movably mounted on a fixed frame, and the gas delivery plate being raised in height as the liquid level in the first reaction tank rises;

[0027] A top liquid pumping structure is provided with a guide frame on the inner side of the first reaction tank body, and the top liquid pumping structure includes a liquid guide tube with a bottom slidingly arranged on the inner side of the ethylene carbonate liquid inlet end, a liquid storage coil is fixedly connected to the top of the liquid guide tube, and the outer side of the liquid storage coil is fitted on the guide frame. A plurality of one-way inlet and outlet parts are provided on the top edge of the liquid storage coil, and an anti-corrosion proximity sensor is provided on the fixed frame. After ethylene carbonate is injected into the ethylene carbonate liquid inlet end, the height of the liquid guide tube and the liquid storage coil rises and approaches the proximity sensor, so that the one-way inlet and outlet parts are opened and the output ethylene carbonate collides and mixes with the descending fluorine-nitrogen mixed gas at the position of the gas transmission plate.

[0028] As a further improvement, the gas delivery disc is connected to the fixed frame via a movable frame, the movable frame includes a first hinge rod arranged on the fixed frame, a telescopic guide rod is provided on the side of the first hinge rod away from the fixed frame, the end of the telescopic guide rod is connected to a second hinge rod, and the second hinge rod is fixed to the outer side of the gas delivery disc.

[0029] As a further improvement, the fixing frame includes an outer mounting ring fixedly connected to the inner wall of the first reaction tank, a π-shaped frame is provided on the inner side of the outer mounting ring extending inward, and the second hinge is locked to the π-shaped frame.

[0030] As a further improvement, the liquid guide tube includes an upper bonding plate tightly attached to the top of the ethylene carbonate liquid inlet end, the lower end of the upper bonding plate is connected to an inner sliding cavity, the bottom of the inner sliding cavity is extended downwardly to provide a lower limit plate, and the initial position of the lower limit plate is spaced apart from the bottom edge of the ethylene carbonate liquid inlet end.

[0031] As a further improvement, a liquid barrier interlayer is provided on the top of the liquid storage coil, and the one-way inlet and outlet member includes a flip member provided in the liquid barrier interlayer, the flip member is connected to a flip valve plate, and the flip member is electrically connected to a proximity sensor.

[0032] The beneficial effects of the present invention are:

[0033] In the existing reaction production equipment for fluoroethylene carbonate, how to make the fluorine-nitrogen mixed gas and ethylene carbonate fully cooperate and react has become a pain point in the industry. If the two cannot fully react, the purity of the generated fluoroethylene carbonate cannot be guaranteed at all. Although fluoroethylene carbonate can be obtained, its purity and the color of the reaction materials cannot be guaranteed at all, which does not meet the industry standards. Therefore, the present invention adds a third-stage reaction component to the existing reaction equipment, and adds a second reaction tank body and a third reaction tank body in the entire reaction process. The fluoroethylene carbonate that has undergone the first reaction is then sequentially introduced into the second reaction tank body and the third reaction tank body and mixed with the newly added quantitative fluorine-nitrogen mixed gas again, thereby fully ensuring the mixing effect of the fluorine-nitrogen mixed gas and ethylene carbonate. The purity of the fluoroethylene carbonate after the three-stage reaction is continuously improved, and its own color becomes more and more transparent. At the same time, the continuous addition of raw materials, the continuous discharge of reaction materials, and the stable reaction discharge components are achieved.

[0034] During the reaction of the three-stage reaction component, the tail gas generated in each reactor is discharged from the top of the reactor. In order to make full use of the effective components in the tail gas, reduce energy consumption, and achieve a high conversion rate of fluorine gas, the reaction tail gas of each reactor is combined and absorbed by the three-stage ethylene carbonate pre-reactor unit in series, forming a closed-loop high-conversion reaction system, and realizing a fluorine gas direct synthesis FEC technology system with automatic quantitative feeding and precise control of the reaction endpoint. The tail gas treated by the three-stage ethylene carbonate pre-reactor unit in series is then subjected to two-stage water washing and one-stage alkali washing to neutralize the unreacted by-product hydrofluoric acid, ensuring clean, environmentally friendly and safe production.

[0035] Through the three-stage reaction components and the ethylene carbonate pre-reactor unit connected in series, materials are continuously supplied to the system during the reaction. The residence time of the materials in the reactor can be controlled by controlling the supply flow rate, so that the main reaction is high and the side reaction is low, thereby increasing the proportion of fluoroethylene carbonate in the generated products and reducing the proportion of difluoroethylene carbonate, thereby reducing the processing pressure of the later distillation.

[0036] In the process of product depickling, if adopt traditional technology, for example, evaporation depickling, falling film evaporation depickling technology, not only energy consumption is high, and complicated operation, therefore the present invention passes into the dry nitrogen or dry air of heating in the depickling still and purges, the flow of nitrogen or air takes HF out of, and final HF drops to a certain amount till.The HF gas blown out is incorporated into the tail gas system and can remove the depickling tail gas absorber and absorb and recycle HF to produce hydrofluoric acid, the gas flow engineering also can carry trace fluoroethylene carbonate liquid secretly, separates and recycles through separating device, this method flow is short, easy to operate, energy consumption is low, solve the problem that traditional depickling system adds organic matter extraction and brings new impurity into, and if bring new impurity into, the bringing into of new impurity can cause subsequent distillation purification difficulty to increase, can produce a large amount of organic waste water simultaneously and cause wastewater treatment difficulty big. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 It is a structural schematic diagram of a preparation system adopted in a preparation process of fluoroethylene carbonate of the present invention.

[0039] Figure 2 It is a structural schematic diagram of a three-stage series reaction mechanism of fluoroethylene carbonate according to the present invention.

[0040] Figure 3 It is a structural schematic diagram of the first reaction tank body of the present invention.

[0041] Figure 4 It is a structural schematic diagram of the mixed gas passage structure of the present invention.

[0042] Figure 5 It is a structural schematic diagram of the top liquid pumping structure of the present invention.

[0043] Figure 6 This is a schematic diagram of the top view of the one-way inlet and outlet of the present invention.

[0044] In the picture:

[0045] First reaction tank 10, first output pipe 11, ethylene carbonate liquid inlet 20, fluorine-nitrogen mixed gas inlet pipe 30, hydrogen fluoride recovery pipe 40, second reaction tank 51, third reaction tank 52, second fluorine-nitrogen mixed gas inlet pipe 53, third fluorine-nitrogen mixed gas inlet pipe 54, fluorine-nitrogen mixed gas distribution table 55, gas outlet valve 551, mixed gas guide structure 60, gas guide pipe 61, gas delivery disk 62, gas delivery hole 63, fixing frame 64, outer mounting ring 641, π-shaped frame 642, wrapping tube 65, first packaging The wrapping portion 651, the second wrapping portion 652, the movable frame 66, the first hinge 661, the telescopic guide rod 662, the second hinge 663, the top liquid pumping structure 70, the liquid guide tube 71, the upper bonding plate 711, the inner sliding cavity tube 712, the lower limit plate 713, the liquid storage coil 72, the liquid barrier interlayer 721, the one-way inlet and outlet part 73, the flip part 731, the flip valve plate 732, the proximity sensor 74, the ethylene carbonate rehydration end 80, the third pre-reactor A1, the second pre-reactor A2, and the first pre-reactor A3. DETAILED DESCRIPTION

[0046] All embodiments of the present invention are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0047] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as referring to the purpose, technical solutions and advantages of the methods. To be clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work indicate or imply relative importance or implicitly indicate the number of indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0048] In this embodiment, ethylene carbonate liquid and a fluorine-nitrogen mixture (20% fluorine gas, 80% nitrogen) undergo a substitution reaction to produce fluoroethylene carbonate. The reaction formula is: C3H4O3+F2→C3H3FO3+HF. Theoretically, the production of 1 ton of fluoroethylene carbonate requires the consumption of 0.83 tons of ethylene carbonate and 0.36 tons of fluorine gas, and also generates 0.19 tons of hydrogen fluoride as a by-product impurity.

[0049] Reference Figures 1 to 6 As shown, a process for preparing fluoroethylene carbonate comprises the following steps:

[0050] S1: connecting the ethylene carbonate liquid inlet 20 to the three-stage series reaction mechanism, and the three-stage series reaction mechanism is connected to the hydrogen fluoride recovery pipe 40 and the fluorine-nitrogen mixed gas distribution station 55 respectively.

[0051] S2: Ethylene carbonate is introduced into the three-stage series reaction mechanism, and the fluorine-nitrogen mixed gas is introduced into the three-stage series reaction mechanism through the fluorine-nitrogen mixed gas distribution table 55 and the fluorine-nitrogen mixed gas inlet pipe 30. The generated material flows out to the semi-finished product receiving tank, and the generated HF tail gas flows into the hydrogen fluoride recovery pipe 40;

[0052] The S2 specifically includes:

[0053] S21: Ethylene carbonate is introduced into the first reaction tank 10 to undergo a primary substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station 55;

[0054] S22: the material after the reaction in the first reaction tank 10 flows into the second reaction tank 51 and undergoes a secondary substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station 55;

[0055] S23: The material after the reaction in the second reaction tank 51 flows into the third reaction tank 52 and undergoes a three-stage substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station 55. The generated material flows from the third reaction tank 52 into the semi-finished product receiving tank.

[0056] In the existing reaction production equipment for fluoroethylene carbonate, how to make the fluorine-nitrogen mixed gas and ethylene carbonate fully cooperate and react has become a pain point in the industry. If the two cannot fully react, the purity of the generated fluoroethylene carbonate cannot be guaranteed at all. Although fluoroethylene carbonate can be obtained, its purity and the color of the reaction materials cannot be guaranteed at all, which does not meet the industry standards. Therefore, the present invention adds a third-stage reaction component to the existing reaction equipment, and adds a second reaction tank body and a third reaction tank body in the entire reaction process. The fluoroethylene carbonate that has undergone the first reaction is then sequentially introduced into the second reaction tank body and the third reaction tank body and mixed with the newly added quantitative fluorine-nitrogen mixed gas again, thereby fully ensuring the mixing effect of the fluorine-nitrogen mixed gas and ethylene carbonate. The purity of the fluoroethylene carbonate after the three-stage reaction is continuously improved, and its own color becomes more and more transparent. At the same time, the continuous addition of raw materials, the continuous discharge of reaction materials, and the stable reaction discharge components are achieved.

[0057] S3: The semi-finished product receiving tank is heated with hot water, and the material is pumped into the deacidification kettle, which is heated and purged with heated dry gas, and the generated HF tail gas is blown into the hydrogen fluoride recovery pipe 40;

[0058] During the deacidification process of the product, if traditional processes such as evaporative deacidification or falling film evaporative deacidification are adopted, not only is energy consumption high, but the operation is also complicated. Since the boiling point of HF is 19.5°C, in this embodiment, the fluorination reaction mixture (85% fluoroethylene carbonate, 4% unreacted ethylene carbonate, 1% by-product bisfluoroethylene carbonate, and 10% by-product HF) is heated to 50-60°C, that is, the temperature of the deacidification kettle is 50-60°C. Heated dry nitrogen or dry air is introduced into the deacidification kettle for purging. The flow of nitrogen or air carries out HF until the HF content is reduced to a certain level. The blown-out HF gas is incorporated into the tail gas system and can be taken to the deacidification tail gas absorption tower for absorption and recovery of HF to produce hydrofluoric acid. The gas flow process will also carry a trace amount of fluoroethylene carbonate liquid, which is separated and recovered through a separation device. This method has a short process, is easy to operate, and has low energy consumption. It solves the problem of new impurities introduced into the traditional deacidification system when adding organic matter extraction. In addition, if new impurities are introduced, the introduction of new impurities will increase the difficulty of subsequent distillation and purification, and will also produce a large amount of organic wastewater, making wastewater treatment difficult.

[0059] S4: The deacidified material is subjected to three-stage distillation using the different boiling points of the components to obtain the final product;

[0060] Among them, the boiling point of HF is 19.5°C, the boiling point of ethylene carbonate is 248°C, the boiling point of fluoroethylene carbonate is 212°C, and the boiling point of difluoroethylene carbonate is about 260°C. Therefore, during distillation, the S4 specifically includes:

[0061] S41: The deacidified material is continuously pumped into a low-boiling distillation tower to separate the light component impurities from the top of the tower and purify the bottom material;

[0062] S42: The bottom material of the first low-boiling distillation tower is pumped into the second low-boiling distillation tower to separate the light component impurities again;

[0063] S43: The bottom material of the secondary low-boiling distillation tower is sent into a high-boiling distillation tower to separate the heavy component impurities, and finally the final product is taken out from the top of the high-boiling tower. The final product is fluoroethylene carbonate.

[0064] S5: The HF tail gas flowing in through the hydrogen fluoride recovery pipe 40 is combined and introduced into the three-stage ethylene carbonate pre-reactor unit in series. The storage tank storing ethylene carbonate is connected to the ethylene carbonate pre-reactor unit to pre-react with the introduced tail gas HF. The pre-reacted ethylene carbonate is introduced into the ethylene carbonate liquid inlet 20 to react with the fluorine-nitrogen mixed gas.

[0065] The ethylene carbonate pre-reactor unit comprises a third pre-reactor A1, a second pre-reactor A2, and a first pre-reactor A3. The combined HF tail gas flows through the third pre-reactor A1 to the second pre-reactor A2 and then to the first pre-reactor A3, and finally flows to the tail gas treatment device through the first pre-reactor A3. The storage tank for storing ethylene carbonate flows into the first pre-reactor A3, the second pre-reactor A2, and the third pre-reactor A1 in sequence to pre-react with the HF tail gas. During the reaction of the three-stage reaction component, the tail gas generated in each reactor is discharged from the top of the reactor. In order to fully utilize the effective components in the tail gas, reduce energy consumption, and achieve a high conversion rate of fluorine gas, the reaction tail gas of each reactor is combined and absorbed by the three-stage ethylene carbonate pre-reactor unit connected in series, forming a closed-loop high-conversion reaction system, and realizing a fluorine gas direct synthesis FEC technology system with automatic quantitative feeding and precise control of the reaction endpoint.

[0066] S6: The tail gas discharged from the ethylene carbonate pre-reaction unit is treated by the tail gas treatment device and then discharged into the atmosphere.

[0067] The tail gas treated by the three-stage ethylene carbonate pre-reactor unit is then washed with two stages of water and one stage of alkali, which can neutralize the unreacted by-product hydrofluoric acid to ensure clean, environmentally friendly and safe production. The tail gas treatment device is an existing technology and will not be described in detail here.

[0068] A first output pipe 11 is provided at the bottom of the first reaction tank body 10, and the three-stage reaction assembly includes a second reaction tank body 51 connected to the first output pipe 11, and the second reaction tank body 51 is connected to a third reaction tank body 52 via a second output pipe 12 on the side away from the first reaction tank body 10, and the second reaction tank body 51 and the third reaction tank body 52 are respectively communicated with a fluorine-nitrogen mixed gas distribution table 55 via a second fluorine-nitrogen mixed gas inlet pipe 53 and a third fluorine-nitrogen mixed gas inlet pipe 54, and the second reaction tank body 51 and the third reaction tank body 52 are both connected to the hydrogen fluoride recovery pipe 40; the mixed gas guide structure 60 includes an air guide pipe 61 whose top is slidingly arranged on the inner side of the fluorine-nitrogen mixed gas inlet pipe 30, and a gas delivery plate 62 is provided at the bottom of the air guide pipe 61, and a plurality of gas delivery holes 63 are opened at the bottom of the gas delivery plate 62, and the outer side of the gas delivery plate 62 is movably mounted to a fixed On the frame 64, the gas delivery disc 62 is raised in height as the liquid level of the first reaction tank body 10 rises; a top liquid pumping structure 70, a guide frame 13 is provided on the inner side of the first reaction tank body 10, the top liquid pumping structure 70 includes a liquid guide tube 71 whose bottom is slidably arranged on the inner side of the ethylene carbonate liquid inlet end 20, and a liquid storage coil 72 is fixedly connected to the top of the liquid guide tube 71. The outer side of the liquid storage coil 72 is attached to the guide frame 13, and the top edge of the liquid storage coil 72 is provided with a plurality of one-way inlet and outlet parts 73. An anti-corrosion proximity sensor 74 is provided on the fixed frame 64. After ethylene carbonate is injected into the ethylene carbonate liquid inlet end 20, the height of the liquid guide tube 71 and the liquid storage coil 72 rises and approaches the proximity sensor 74, allowing the one-way inlet and outlet parts 73 to open and output ethylene carbonate and the downward fluorine-nitrogen mixed gas to collide and mix at the position of the gas delivery disc 62.

[0069] Interlayers are provided on the outside of the first reaction tank body 10, the second reaction tank body 51 and the third reaction tank body 52 for performing cold treatment or heat treatment on the reaction tank bodies. The circulation method of the refrigerant or heat medium is the existing technology and will not be described in detail here.

[0070] During the entire reaction process, the ethylene carbonate inlet 20 and the fluoroethylene carbonate outlet are both located at the lower end of the reaction tank, while the fluorine-nitrogen mixed gas inlet and the hydrogen fluoride recovery are both located at the upper end of the reaction tank.

[0071] In this embodiment, the mixed gas guiding structure 60 and the top liquid pumping structure 70 are only arranged in the first reaction tank body 10, and the mixing between the two raw materials is only promoted in the first reaction tank body 10. The mixed gas guiding structure 60 and the top liquid pumping structure 70 may not be set in the subsequent second reaction tank body 51 and the third reaction tank body 52.

[0072] In the existing reaction production equipment for fluoroethylene carbonate, how to make the fluorine-nitrogen mixed gas and ethylene carbonate fully cooperate and react has become a pain point in the industry. If the two cannot fully react, the purity of the generated fluoroethylene carbonate cannot be guaranteed at all. Although fluoroethylene carbonate can be obtained, its purity and the color of the reaction materials cannot be guaranteed at all, which does not meet the industry standards. Therefore, the present invention adds a third-stage reaction component to the existing reaction equipment, and adds a second reaction tank body 51 and a third reaction tank body 52 in the entire reaction process. The fluoroethylene carbonate that has undergone one reaction is then sequentially introduced into the second reaction tank body 51 and the third reaction tank body 52 and mixed with the newly added quantitative fluorine-nitrogen mixed gas again, so that the mixing effect of the fluorine-nitrogen mixed gas and ethylene carbonate can be fully guaranteed. The purity of the fluoroethylene carbonate after the three-stage reaction is continuously improved, and its own color becomes more and more transparent. At the same time, the continuous addition of raw materials, the continuous discharge of reaction materials, and the stable reaction discharge components are achieved.

[0073] During the entire three-stage series reaction process, since the purity of the fluoroethylene carbonate in different reaction tanks is different, the required fluorine-nitrogen mixed gas is also different. Therefore, the fluorine-nitrogen mixed gas distribution table 55 of this embodiment is respectively provided with a plurality of gas outlet valves 551 corresponding to the first reaction tank 10, the second reaction tank 51, and the third reaction tank 52. The opening degrees of the different gas outlet valves 551 are different. By managing the opening degrees of the gas outlet valves 551 of the first reaction tank 10, the second reaction tank 51, and the third reaction tank 52 at different levels on the fluorine-nitrogen mixed gas distribution table 55, different amounts of fluorine-nitrogen mixed gas are output at different links, thereby improving the control of the purity of the fluoroethylene carbonate.

[0074] During the process of adding the fluorine-nitrogen mixture to the reaction tank, since the by-product hydrogen fluoride is generated during the entire reaction, some of the fluorine-nitrogen mixture will be lost. Therefore, the present invention adds a mixture gas guide structure 60 on the basis of the three-stage reaction component, so that the fluorine-nitrogen mixture can be directly discharged through the downwardly extending gas transmission plate 62 when the material is discharged. The outlet position is extended to the liquid surface of the ethylene carbonate or the inside of the liquid, and fully reacts with the ethylene carbonate. When the hydrogen fluoride overflows, only a small amount of the fluorine-nitrogen mixture is carried away. This not only improves the overall reaction uniformity, but also reduces the loss of raw materials, further reducing the cost of the enterprise.

[0075] The depth of the air guide pipe 61 in the fluorine-nitrogen mixture gas intake pipe 30 will change with the liquid level. In order to make the two fit better, the wrapping tube 65 of this embodiment is wider at the top and narrower at the bottom. The wrapping tube 65 includes a first wrapping portion 651 that is tightly attached to the outside of the fluorine-nitrogen mixture gas intake pipe 30. The lower end of the first wrapping portion 651 is connected to a second wrapping portion 652 that is attached to the outside of the air guide pipe 61. By arranging the wrapping tube 65 between the air guide pipe 61 and the fluorine-nitrogen mixture gas intake pipe 30, the wrapping tube 65 fixed on the fluorine-nitrogen mixture gas intake pipe 30 can play a certain auxiliary limiting effect on the air guide pipe 61, so that it can be smoother in the process of up and down displacement, and avoid the phenomenon of it being stuck in the fluorine-nitrogen mixture gas intake pipe 30.

[0076] In fact, if the entire mixed gas guiding structure 60 is only supported and fixed by the wrapping tube 65 and the air guide pipe 61, the stability of the mixed gas guiding structure 60 cannot be guaranteed when the liquid level is low. Therefore, the gas delivery plate 62 of this embodiment is connected to the fixed frame 64 through a movable frame 66. The movable frame 66 includes a first hinge 661 arranged on the fixed frame 64. A telescopic guide rod 662 is provided on the side of the first hinge 661 away from the fixed frame 64. The end of the telescopic guide rod 662 is connected to a second hinge 663. The second hinge 663 is fixed to the outer side of the gas delivery plate 62. The mixed gas guiding structure 60 can be hung by the movable frame 66 when the liquid level is low, and deformed accordingly when the liquid level is high, thereby adapting to the constantly changing liquid level. Specifically, the direction of the gas delivery plate 62 is changed by hinged connection at both ends and telescopic middle part, so that the gas delivery plate 62 can achieve stable up and down position conversion.

[0077] Compared with the gas delivery disc 62, which frequently changes its position, the position of the fixing frame 64 remains unchanged. However, in order to facilitate the circulation of by-products and increase the contact area, the entire fixing frame 64 needs to be set to be permeable. Therefore, in this embodiment, the fixing frame 64 includes an outer mounting ring 641 fixed to the inner wall of the first reaction tank body 10. A π-shaped frame 642 is provided on the inner side of the outer mounting ring 641, and the second hinge 663 is locked to the π-shaped frame 642. The π-shaped frame 642 is mostly a hollow structure, and only one lateral end thereof is in contact with the gas delivery disc 62, so that there is sufficient space for gas passage and mixing.

[0078] After the mixed gas conducting structure 60 realizes gas discharge from the liquid surface, if the liquid level of the reaction tank body increases in a normal manner, it is very easy to cause the ethylene carbonate at the bottom to be unable to fully contact with the fluorine-nitrogen mixed gas. If relying on the flow of the solution itself and the penetration of the gas, it is necessary to wait for a long time, which prolongs the cycle of the entire continuous reaction. Therefore, the present invention provides a top liquid pumping structure 70 based on the mixed gas conducting structure 60. When discharging the liquid, the ethylene carbonate will only be discharged through the one-way inlet and outlet part 73 at the top. The output ethylene carbonate is then mixed and reacted with the gas output by the gas supply plate 62, so that the continuously input ethylene carbonate can fully contact with the continuously input fluorine-nitrogen mixed gas, thereby improving the mixing degree of the two and making the generated fluoroethylene carbonate more pure.

[0079] During the use of the top liquid pumping structure 70, the present embodiment sets the liquid guide tube 71 as an "I"-shaped structure. Specifically, the liquid guide tube 71 includes an upper fitting plate 711 that is tightly attached to the top of the ethylene carbonate liquid inlet end 20. The lower end of the upper fitting plate 711 is connected to an inner sliding cavity tube 712. The bottom of the inner sliding cavity tube 712 extends downward to be provided with a lower limit plate 713. The initial position of the lower limit plate 713 is spaced apart from the bottom edge of the ethylene carbonate liquid inlet end 20, so that the liquid inlet end 20 is continuously pressurized. When the liquid coil 72 moves upward due to being filled, it drives the lower limit plate 713 to move upward, causing the height of the entire liquid storage coil 72 to rise, thereby bringing the liquid storage coil 72 close to the proximity sensor 74, causing the one-way inlet and outlet part 73 to open and discharge liquid. After the liquid is pumped out, the pressure decreases and then falls back, thereby continuously generating a pulse-like cycle. During the entire process, the continuous back and forth movement of the liquid storage coil 72 will disturb the ethylene carbonate or the generated fluoroethylene carbonate, thereby promoting the progress of the entire reaction.

[0080] Due to the corrosiveness of fluorine-containing substances, a liquid barrier interlayer 721 is provided on the top of the liquid storage coil 72. The one-way inlet and outlet member 73 includes a flip member 731 provided in the liquid barrier interlayer 721. The flip member 731 is connected to a flip valve plate 732. The flip member 731 is electrically connected to the proximity sensor 74, so that the flip member 731, that is, the micro motor, can be protected, and a separate anti-corrosion protection is provided at the position where the output end of the flip member 731 extends to prevent it from being damaged.

[0081] During the reaction process of the second reaction tank 51 and the third reaction tank 52, in order to avoid insufficient ethylene carbonate during the reaction process, the lower ends of the second reaction tank 51 and the third reaction tank 52 are both provided with ethylene carbonate replenishing ends 80, thereby ensuring the continuous progress of the entire reaction.

[0082] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A process for preparing fluoroethylene carbonate, characterized in that: The steps include: S1: connecting the ethylene carbonate liquid inlet (20) to the three-stage series reaction mechanism, and the three-stage series reaction mechanism is connected to the hydrogen fluoride recovery pipe (40) and the fluorine-nitrogen mixed gas distribution station (55) respectively; The three-stage series reaction mechanism in S1 includes: A three-stage reaction assembly, wherein a first output pipe (11) is provided at the bottom of a first reaction tank body (10), the three-stage reaction assembly comprises a second reaction tank body (51) connected to the first output pipe (11), a side of the second reaction tank body (51) away from the first reaction tank body (10) is connected to a third reaction tank body (52) via a second output pipe (12), the second reaction tank body (51) and the third reaction tank body (52) are respectively connected to a fluorine-nitrogen mixed gas distribution table (55) via a second fluorine-nitrogen mixed gas inlet pipe (53) and a third fluorine-nitrogen mixed gas inlet pipe (54), and the second reaction tank body (51) and the third reaction tank body (52) are both connected to a hydrogen fluoride recovery pipe (40); A mixed gas guide structure (60) comprises an air guide pipe (61) whose top is slidably arranged inside the fluorine-nitrogen mixed gas inlet pipe (30), a gas delivery plate (62) being arranged at the bottom of the air guide pipe (61), a plurality of gas delivery holes (63) being opened at the bottom of the gas delivery plate (62), an outer side of the gas delivery plate (62) being movably mounted on a fixing frame (64), and the gas delivery plate (62) is raised in height as the liquid level in the first reaction tank body (10) rises; A top liquid pumping structure (70), wherein a guide frame (13) is provided on the inner side of the first reaction tank body (10), and the top liquid pumping structure (70) comprises a liquid guide tube (71) whose bottom is slidably provided on the inner side of the ethylene carbonate liquid inlet end (20), a liquid storage coil (72) is fixedly connected to the top of the liquid guide tube (71), and the outer side of the liquid storage coil (72) is attached to the guide frame (13), and a plurality of one-way inlet and outlet parts (73) are provided on the top edge of the liquid storage coil (72), and an anti-corrosion proximity sensor (74) is provided on the fixing frame (64), and after the ethylene carbonate is pumped into the ethylene carbonate liquid inlet end (20), the height of the liquid guide tube (71) and the liquid storage coil (72) rises and approaches the proximity sensor (74), so that the one-way inlet and outlet parts (73) are opened and the ethylene carbonate is output to collide and mix with the descending fluorine-nitrogen mixed gas at the position of the gas transmission plate (62); S2: Ethylene carbonate is introduced into the three-stage series reaction mechanism, and the fluorine-nitrogen mixed gas is introduced into the three-stage series reaction mechanism through the fluorine-nitrogen mixed gas distribution table (55) and the fluorine-nitrogen mixed gas inlet pipe (30), and the generated material flows out to the semi-finished product receiving tank, and the generated HF tail gas flows into the hydrogen fluoride recovery pipe (40); S3: The semi-finished product receiving tank is heated with hot water, and the material is pumped into the deacidification kettle, the deacidification kettle is heated, heated dry gas is introduced for purging, and the generated HF tail gas is blown into the hydrogen fluoride recovery pipe (40); S4: The deacidified material is subjected to three-stage distillation using the different boiling points of the components to obtain the final product; S5: The HF tail gas flowing in through the hydrogen fluoride recovery pipe (40) is merged and introduced into the three-stage ethylene carbonate pre-reaction unit in series, and the storage tank storing ethylene carbonate is connected to the ethylene carbonate pre-reaction unit to pre-react with the introduced tail gas HF. The pre-reacted ethylene carbonate is introduced into the ethylene carbonate liquid inlet (20) to react with the fluorine-nitrogen mixed gas; S6: The tail gas discharged from the ethylene carbonate pre-reaction unit is treated by the tail gas treatment device and then discharged.

2. A process for preparing fluoroethylene carbonate according to claim 1, characterized in that: The S2 specifically includes: S21: Ethylene carbonate is introduced into the first reaction tank (10) to undergo a primary substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station (55); S22: the material after the reaction in the first reaction tank (10) flows into the second reaction tank (51) and undergoes a secondary substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station (55); S23: The material after the reaction in the second reaction tank (51) flows into the third reaction tank (52) and undergoes a three-stage substitution reaction with the fluorine-nitrogen mixed gas input from the fluorine-nitrogen mixed gas distribution station (55). The generated material flows from the third reaction tank (52) into the semi-finished product receiving tank.

3. A process for preparing fluoroethylene carbonate according to claim 1, characterized in that: The temperature of the deacidification kettle is 50-60°C.

4. The process for preparing fluoroethylene carbonate according to claim 1, wherein: The S4 specifically includes: S41: The deacidified material is continuously pumped into a low-boiling distillation tower to separate the light component impurities from the top of the tower and purify the bottom material; S42: The bottom material of the first low-boiling distillation tower is pumped into the second low-boiling distillation tower to separate the light component impurities again; S43: The bottom material of the secondary low-boiling distillation tower is pumped into a high-boiling distillation tower to separate the heavy component impurities, and finally the final product is extracted from the top of the high-boiling tower.

5. The process for preparing fluoroethylene carbonate according to claim 1, wherein: The ethylene carbonate pre-reactor unit comprises a third pre-reactor (A1), a second pre-reactor (A2), and a first pre-reactor (A3). The combined HF tail gas flows through the third pre-reactor (A1) to the second pre-reactor (A2) and then to the first pre-reactor (A3), and finally flows through the first pre-reactor (A3) to the tail gas treatment device. The storage tank for storing ethylene carbonate flows into the first pre-reactor (A3), the second pre-reactor (A2), and the third pre-reactor (A1) in sequence to perform a pre-reaction with the HF tail gas.

6. The process for preparing fluoroethylene carbonate according to claim 1, wherein: The gas delivery disc (62) is connected to the fixed frame (64) via a movable frame (66). The movable frame (66) includes a first hinge rod (661) arranged on the fixed frame (64). A telescopic guide rod (662) is provided on the side of the first hinge rod (661) away from the fixed frame (64). The end of the telescopic guide rod (662) is connected to a second hinge rod (663). The second hinge rod (663) is fixed to the outer side of the gas delivery disc (62).

7. A process for preparing fluoroethylene carbonate according to claim 6, characterized in that: The fixing frame (64) includes an outer mounting ring (641) fixedly connected to the inner wall of the first reaction tank body (10), and a π-shaped frame (642) is provided on the inner side of the outer mounting ring (641) extending inward, and the second hinge rod (663) is locked on the π-shaped frame (642).

8. The process for preparing fluoroethylene carbonate according to claim 1, wherein: The liquid guide tube (71) includes an upper bonding plate (711) tightly attached to the top of the ethylene carbonate liquid inlet end (20), the lower end of the upper bonding plate (711) is connected to an inner sliding cavity (712), and the bottom of the inner sliding cavity (712) is provided with a lower limit plate (713) extending downward, and the initial position of the lower limit plate (713) is spaced apart from the bottom edge of the ethylene carbonate liquid inlet end (20).

9. The process for preparing fluoroethylene carbonate according to claim 8, wherein: A liquid barrier interlayer (721) is provided on the top of the liquid storage coil (72), and the one-way inlet and outlet member (73) includes a flip member (731) provided in the liquid barrier interlayer (721), the flip member (731) is connected to a flip valve plate (732), and the flip member (731) is electrically connected to a proximity sensor (74).

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