CN110650949A - Rapid continuous flow synthesis process of fluoroethylene carbonate - Google Patents

Abstract

The invention relates to a rapid continuous flow synthesis process of fluoroethylene carbonate and an integrated continuous flow reactor for realizing the process, wherein the continuous flow synthesis process takes a raw material to be fluorinated and fluorine gas as reactants and continuously and sequentially carries out the steps of mixing dispersion, fluorination reaction and gas-liquid separation to obtain the fluoroethylene carbonate, the synthesis process is carried out in the integrated continuous flow reactor, the raw material to be fluorinated and the fluorine gas are uninterruptedly added into a feed inlet of the integrated continuous flow reactor, the fluoroethylene carbonate is obtained uninterruptedly at a discharge outlet of the integrated continuous flow reactor, and the reaction time is equal to or less than 600 s. The process is a continuous synthesis process of fluoroethylene carbonate, which is rapid, safe, efficient, strong in universality and easy for large-scale production.

Description

Rapid continuous flow synthesis process of fluoroethylene carbonate Technical Field

The invention relates to the field of chemistry, in particular to a rapid continuous flow synthesis process of fluoroethylene carbonate.

Background

Fluorine-containing compounds (especially organofluorine compounds, i.e., partially and fully fluorinated organic compounds) are excellent and commercially valuable chemicals. The fluorine-containing compound can exhibit various properties such as inertness, non-polarity, hydrophobicity, oleophobicity, and the like, and thus has a very wide range of applications. The fluoro organic carbonate is an important organic fluorine compound (organic is called as organic fluoride), can be used as a solvent and a solvent additive of a lithium ion battery, has better performance of forming a solid electrolyte interface film (SEI film), can form a compact structure layer without increasing impedance, can prevent the electrolyte from being further decomposed, has a flame retardant effect, improves the low-temperature performance of the electrolyte, obviously prolongs the cycle life of the battery, and improves the safety performance of the battery. Of these, fluoroethylene carbonate is an important product.

The synthetic process route of fluoroethylene carbonate mainly comprises the following steps:

the electrochemical fluorination method for the industrial production of organic fluorine compounds was first put into industrial production by 3M company. This fluorination process, commonly referred to as "Simons electrochemical fluorination", requires electrolysis of an electrolyte solution containing liquid anhydrous hydrogen fluoride and organic compound starting materials, and has the disadvantages of high energy consumption and the need to use anhydrous hydrogen fluoride. Another electrochemical fluorination principle is electrolysis in a salt melt (e.g. a potassium fluoride/hydrogen fluoride melt), which is known as the phillips process. This type of process was improved in CN103261484A by basf european corporation, using hydrogen fluoride complex instead of anhydrous hydrogen fluoride or salt melt as fluorinating agent in electrolyte, and applying it to the preparation of fluoro organic carbonate, but still consuming a lot of electric energy in the process, which is costly.

Another method for industrially producing a fluorinated organic carbonate is the halogen exchange method, i.e., a method for synthesizing a fluorinated organic carbonate by Finkelstein halogen exchange Reaction. Such processes generally involve chlorination of organic compounds to produce chlorinated organic carbonates, purification and reaction with fluorinating reagents (HF or KF) to produce fluorinated organic carbonates. For example, the route for the synthesis of monofluoroethylene carbonate by the halogen exchange method is as follows:

the chlorination reaction in the first step is reported more, the process is relatively mature, and the operation and control are easy compared with the fluorination reaction. However, the fluoroethylene carbonate synthesized by the method needs to undergo two steps of reactions, and in order to reduce impurities of halogen exchange reaction and obtain high-purity fluoro organic carbonate, the intermediate chloroethylene carbonate needs to be subjected to multiple purification processes including washing, neutralization, drying, rectification and the like, so that the process is complicated, and the production efficiency is reduced. In addition, according to the existing reports, the total yield of monofluoroethylene carbonate prepared by two-step reaction is 60-65%, which is not ideal.

Patent CN105541783A relates to a method for producing fluoroethylene carbonate, in which fluoroethylene carbonate is obtained by three steps of chlorination, elimination and addition using ethylene carbonate as raw material, the process route is shown as follows, both intermediate chloroethylene carbonate and vinylene carbonate need to be purified (rectification is needed to obtain chloroethylene carbonate, and vacuum refining is needed to obtain vinylene carbonate) for the next step of reaction, compared with the direct fluorination method, the reaction steps and process steps are increased a lot, the production efficiency is reduced, and the yield of fluoroethylene carbonate is not improved compared with the halogen exchange method, and is only 56.5% calculated by chloroethylene carbonate.

A further feasible route for the synthesis of fluoroethylene carbonate is direct fluorination, in which fluoroethylene carbonate is synthesized by direct substitution reaction of ethylene carbonate with fluorine gas or a mixed gas of fluorine gas and an inert gas (e.g., nitrogen gas), for example, the route for the synthesis of monofluoroethylene carbonate by direct fluorination is as follows:

compared with a halogen exchange method, the method has the advantages that one-step reaction is carried out, the process route is simpler, the reaction is easy to generate, the conditions are mild, the fluorination reaction can be rapidly completed at relatively low temperature theoretically due to the high reaction activity of fluorine gas, and the production efficiency is higher. However, this method has drawbacks such as the large toxicity of the raw material fluorine gas; the high reactivity of fluorine gas causes the process to release heat violently, which is easy to cause the pressure in the reactor to be higher and cause danger; fluorine gas is highly corrosive and has high requirements for reaction equipment. For these reasons, there are few reports of processes using the direct fluorination method, and the industrial application is also greatly limited.

Fluorine gas is a highly toxic gas and can irritate the eyes, skin, and respiratory mucosa. When the fluorine concentration is 5-10 ppm, the compound has stimulation effect on mucous membranes of eyes, nose, throat and the like, and pulmonary edema can be caused after long-term action. Contact with the skin can cause burning of hair, coagulation necrosis of the contact site, carbonization of epithelial tissue, and the like. Chronic contact can cause osteopetrosis and ligament calcification. To ensure the safety of personnel, the maximum allowable concentration in the air is 0.1ppm (0.2mg/m 3). Direct fluorination using fluorine gas thus places high demands on plant and process safety, including containment and off-gas treatment facilities.

Elemental fluorine is the most electronegative element, the chemical property of the elemental fluorine gas is very active, and most elements, including some inert gases, can react with the elemental fluorine gas to form compounds. Fluorine gas has a strong oxidizing property and can be burned by a strong reaction with most oxidizable substances or organic substances at room temperature, for example, alkali metals can explode in fluorine gas, many nonmetals such as silicon, phosphorus, sulfur and the like can also be burned in fluorine gas, and most organic compounds are highly susceptible to combustion and explosion by reaction with fluorine gas. The exothermic heat of substitution reaction of the organic compound with fluorine gas is large, for example, if the organic compound is subjected to monofluoro reaction with fluorine gas, the exothermic heat of reaction is about 482kJ/mol, while for similar monofluoro reaction with chlorine and bromine, the exothermic heat of reaction is about 101kJ/mol and 34kJ/mol, respectively, i.e., the exothermic heat of fluoro reaction is about 5 times that of similar chloro reaction and is about one order of magnitude larger than that of similar bromo reaction, and the exothermic heat is multiplied if the organic compound is subjected to polyfluoro reaction (for example, the exothermic heat of difluoro reaction is about 964 kJ/mol). Therefore, compared with similar substitution reactions (such as chlorination, bromination and the like), the fluorination reaction using fluorine gas or the mixed gas of fluorine gas and inert gas as the raw material has the characteristics of large heat release, very high heat transfer requirement on the process, and increased difficulty in process development. In addition, the existing process for synthesizing fluoroethylene carbonate cannot realize the synthesis of various fluoroethylene carbonate and the mixture thereof by using the same set of reactor only through simple adjustment of process parameters (for example, the fluoroethylene carbonate is synthesized by using ethylene carbonate as a raw material, or the difluoroethylene carbonate is synthesized by using ethylene carbonate as a raw material, or the trifluoroethylene carbonate is synthesized by using monofluoroethylene carbonate as a raw material).

The substitution reaction of fluorine gas and organic compound is easy to occur and the process is violent, the reaction is easy to excessively reduce the selectivity due to poor control, a mixture of products with different fluorination degrees is generated, the yield of the target product is reduced, and the difficulty of separation and refining is increased. Generally, the selectivity of the monofluoro substitution reaction of the raw material to be fluorinated is better than that of other number fluoro substitution (for example, difluoro, trifluoro, and tetrafluoro) reactions, and the corresponding process conditions are easy to control, for example, chinese patents CN1810764A and CN201080042843A report that the selectivity of the synthesis of monofluoro ethylene carbonate from ethylene carbonate as the raw material is higher than that of the synthesis of difluoroethylene carbonate, trifluoroethylene carbonate, and tetrafluoroethylene carbonate, the former is more than 95%, and the latter three are not more than 80%. Furthermore, the proportion of the target product in the crude reaction product is also high, and the selectivity for preparing monofluoroethylene carbonate is reported to be up to 95% at most, but the selectivity for preparing difluoroethylene carbonate, trifluoroethylene carbonate and tetrafluoroethylene carbonate is not more than 75% at most. That is, the conventional method has not been able to solve the problem of selectivity of direct fluorination reaction.

The corrosion of fluorine gas is very strong, and most of metals and non-metals are corroded, so that the direct fluorination method has high requirements on the material and structure of reaction equipment, and simultaneously, the fluorine gas is required to be completely consumed in the process, the conversion rate of the fluorine gas is improved, the waste is reduced, and the risk of tail gas treatment is reduced.

The direct fluorination reaction of ethylene carbonate and fluorine gas is a gas-liquid two-phase heterogeneous reaction, and the reaction is usually a combination of mass transfer process and reaction process, and the macroscopic reaction rate is influenced by the intrinsic reaction rate and the mass transfer rate. The fluorination reaction of ethylene carbonate and fluorine gas belongs to rapid reaction, so the macroscopic reaction rate is greatly influenced by mass transfer factors, and the full contact and good mixing of gas phase and liquid phase are favorable for the rapid and complete reaction. In heterogeneous reactions, two phases with close volumes are generally considered to be mixed, and the mixing effect is better. However, in the gas-liquid two-phase reaction, the volume difference between the gas phase and the liquid phase is large. For example, ethylene carbonate undergoes monofluorination with elemental fluorine (pure fluorine gas), and the volume ratio of gas phase to liquid phase is as high as 336:1 in terms of theoretical molar ratio. If the polyfluorination reaction is carried out, the volume difference between the gas phase and the liquid phase is multiplied, for example, the vinyl carbonate and the fluorine simple substance (pure fluorine gas) carry out the difluoroamination reaction, and the volume ratio of the gas phase to the liquid phase is 672:1 according to the theoretical molar ratio. Or the fluorizating reagent adopts the mixed gas of fluorine gas and inert gas, and the volume difference between the gas phase and the liquid phase is larger. For example, ethylene carbonate and mixed gas of fluorine simple substance and nitrogen gas with the volume concentration of 20% have a monofluoro reaction, and according to the theoretical molar ratio, the volume ratio of gas phase and liquid phase is as high as 1680: 1. The gas/liquid dispersion specific surface area is generally adopted to measure the mixing effect of the gas phase and the liquid phase, and the larger the gas/liquid dispersion specific surface area is, the better the gas phase and the liquid phase are mixed.

In summary, although the synthesis of fluoroethylene carbonate by the direct fluorination method has theoretical reaction advantages (high reactivity of fluorine, rapid reaction at low temperature, few reaction steps, and high production efficiency), the method has the following disadvantages: 1) the controllability of the reaction is poor, which shows that the heat release is large, the reaction is easy to be out of control and has large danger; 2) because of the heterogeneous reaction of gas phase and liquid phase with huge volume difference, the gas phase and the liquid phase are difficult to realize uniform mixing, the reaction has very high requirement on the mass transfer of a reaction system, otherwise, the full reaction is difficult to realize; 3) the process selectivity is poor, the flexibility is low, the exothermic amount and the gas-liquid phase volume ratio of different degrees of fluorination reactions (e.g., monofluorination reaction, difluorofluorination reaction, trifluorofluorination reaction, tetrafluorofluorination reaction, etc.) of the same raw material are greatly different, and the physical properties (e.g., melting point, thermal conductivity, heat capacity, solubility, etc.) and the reactivity of different raw materials are also greatly different, so that the conditions corresponding to the fluorination reactions are greatly different, it is difficult to control a certain degree of fluorination reactions to occur with high selectivity, and it is difficult for one reactor to simultaneously satisfy the synthesis conditions of a plurality of fluorinated products.

In the prior art, a process which can not only fully exert the reaction advantages of the direct fluorination method, but also overcome the three defects of the method is not developed, namely: the method fully solves the problems of heat transfer and mass transfer, also considers the physical properties (such as melting point, thermal conductivity, heat capacity, solubility and the like) and the difference of reaction activity of different raw materials, and solves the problems of process selectivity and flexibility, so that the direct fluorination reaction is highly controllable, the reaction efficiency is high (the reaction is rapid, the yield of target products is high), and the equipment universality is good (products with different fluorination degrees can be efficiently produced by adopting the same reactor).

In the existing industrial production, the fluoroethylene carbonate synthesized by the direct fluorination method mostly adopts an intermittent process, namely: by bubbling fluorine gas or a mixture of fluorine gas and an inert gas into a reaction vessel containing a predetermined amount of the raw material, e.g. by introducing fluorine gas or a mixture of fluorine gas and an inert gasPatents CN1747946A, CN100343245C and JP2000309583A specifically describe batch tank processes of the type described above. Except for the problems of low production efficiency and complicated operation inherent in the batch process, the gas-liquid two-phase reaction is carried out by using a gas bubbling mode, and the problems of low reaction efficiency and conversion rate of fluorine gas, poor reaction selectivity, long reaction time and the like exist because the gas-liquid two-phase contact is limited. Chinese patent CN1810764A improves the method, and F is supplied to ethylene carbonate₂/N₂When gas is mixed, the bubble adjusting column filled with the filler is used for adjusting the size of bubbles and optimizing the shape of the reactor, so that the contact time and the contact area of gas phase and liquid phase are increased, the reaction efficiency is increased, and the reaction time is correspondingly shortened. The FEC yield can reach 82% at 50 ℃. However, the reaction is a batch process and still takes several hours, N is required after the reaction of each batch₂The gas purges the reactor of residual gases, which limits the overall efficiency of fluoroethylene carbonate production.

Batch process is to wait for a certain time (including the reaction time, temperature reduction time, temperature rise time, heat preservation time of each step, interval waiting time of each operation and the like) after raw materials are added into a reactor, discharge products once after the reaction meets certain requirements, namely, the production mode of the products is divided into batches, and each batch can only produce a limited fixed number of products (the number of the products depends on the volume of the reactor). The total reaction time of the batch process refers to the total time from raw materials to the prepared product, and comprises the charging time, the reaction time, the discharging time, the material transferring time, the cooling time, the heating time, the heat preservation time, the interval waiting time of each operation and the like of each step. In the intermittent process operation process, the state parameters of the composition, the temperature and the like of materials (including intermediate products and final products) in the reactor can change along with time, the process is an unstable process, the production process and the product quality have great uncertainty, and the quality of downstream products is directly unstable and difficult to control.

The most important features of a batch process are two-fold, one is the presence of "stops" or "interruptions" in the process, and the other is that the production of products is spaced apart, i.e., there are batches of product and only a fixed amount of product is available for a batch. That is, for each batch of production, a fixed number of starting materials are reacted in the order of reaction steps to ultimately yield a limited fixed number of products (products); then, a fixed amount of raw materials are put in, and the next batch of reaction is carried out according to the same steps to obtain a limited fixed amount of products.

There are two ways to implement a batch process: 1) respectively using a plurality of reactors (such as flasks, reaction kettles and the like), wherein each reaction is carried out in one reactor; 2) the method is realized by using a reactor (such as a flask, a reaction kettle and the like), wherein each step of reaction is sequentially completed, a plurality of raw materials are sequentially added according to the reaction progress in the reaction process, namely, after each step of reaction, the raw materials are stopped to wait for further addition of the raw materials for the subsequent reaction. Some documents also refer to mode 2) as continuous (continuous), which is also intermittent in nature because of "standing" in the process, waiting for the addition, or requiring adjustment to a suitable temperature for the next reaction (e.g., warming, cooling, or holding).

Through the improvement of the existing device and process method, on the continuous method of direct fluorination, some attempts are made to only partially solve but only solve the three defects to a certain extent, and the problems of long reaction time, low production efficiency, poor process and device flexibility and poor selectivity still exist.

Chinese patent CN1075313A relates to a method for directly fluorinating fluorinated cyclic or acyclic carbonate to synthesize corresponding fluorinated carbonate and reacting the generated fluorinated carbonate with active nucleophile to synthesize corresponding fluorinated functional compound. The process may be carried out in batch, semi-continuous or continuous mode, the reaction apparatus being a temperature controlled reactor not described in detail, and no particular mention is made of fluoroethylene carbonate synthesis. The method is not necessarily applicable to fluoroethylene carbonate synthesis because of the large difference in physical properties (e.g., melting point, thermal conductivity, heat capacity, solubility, etc.) and reactivity of different raw materials, and the process conditions and parameters for a particular raw material and a particular reaction process will be different. Although the method realizes continuity, the following main problems still exist: firstly, the process operation is complicated, an inert liquid reaction medium needs to be pre-filled in a reactor, and the quality of the inert liquid medium in the reactor needs to be kept at a constant level by supplementing liquid (recycled or new) in the process; secondly, the reaction time is long, the reaction efficiency is low, and only the fluorination process of hectogram samples needs to be injected for several hours or even more than ten hours, so that the expansion of the production scale is greatly limited. US patents US5420359A, US20020027172a1, US6863211B2, US6491983B2 and US20030166487a1 all relate to similar processes, with the same disadvantages. In a word, the process and the device thereof only connect the steps in the original intermittence, and firstly, the problems of long time consumption, poor flexibility and low production efficiency of the process cannot be solved, the direct fluorination reaction cannot be completed in a short time (within 10 minutes), and the problems of poor controllability, mass transfer, flexibility and selectivity of the direct fluorination method cannot be solved; the second process is not a continuous flow process, which means that the materials (i.e. the reaction mixture containing raw materials, intermediates, products, solvents, etc.) are continuously flowing during the production process, and no stay waiting is left, i.e. the products are continuously produced. Of course, it is mentioned that continuous processes generally give higher yields, better product quality and more efficient use of fluorine than batch and semi-continuous processes.

Chinese patent CN1104930A relates to a method for direct fluorination of organic matter in a tubular reactor. The process comprises mixing the feedstock and inert liquid medium in an upstream conduit, transporting the mixture to a tubular reactor through a fluid transfer device, mixing the mixture with fluorine gas therein, and circulating the mixture for a sufficient time to produce the desired fluorinated product. The examples do not mention the synthesis of fluoroethylene carbonate. The method mainly has the problems that the circulating fluorination of a reaction mixture in a reactor is too long, the time from hours to days or even weeks is needed, the reaction efficiency is very low, the direct fluorination cannot be completed in a short time (within 10 minutes), and the problems of poor controllability, mass transfer, flexibility and selectivity existing in the direct fluorination method are not solved.

Chinese patent CN102548949A relates to a method for the continuous preparation of corresponding fluoroethylene carbonate and dimethyl fluorocarbonate from ethylene carbonate and dimethyl carbonate and an apparatus for carrying out the method. Reacting with F in the course of reaction₂/N₂The mixed gas is continuously introduced into the reactor cascade, and the reaction mixture is withdrawn from the reactor cascade and the target product is separated by continuous distillation. The highest conversion rate of the organic carbonate is 70 percent within the range of 10-70 ℃. The process mainly has the following problems:

firstly, the core reaction equipment is a plurality of (2-5) reactor cascade with partition plates, namely, the reactor cascade is a simply connected so-called 'continuous', materials still stay and wait in each reactor, and the reactor cascade is not continuous; in addition, the device comprises an additional cooler for circulating a part of the reaction mixture to remove a large amount of reaction heat generated in the fluorination reaction; at the same time, in order to achieve a good mixing of the reaction mixture, it is necessary to introduce the fluorine gas into the reactor in a finely dispersed form through a glass frit beforehand. The reaction device is additionally provided with various auxiliary devices for meeting the heat and mass transfer requirements of the fluorination reaction, and has low integration degree and complex structure. In general, the reactor apparatus is not an integrated continuous flow reactor and multiple reactor cascades are necessary to complete the reaction.

Secondly, the residence time is still longer, and the reaction time of the method is at least 30 minutes.

Thirdly, the operation of the process is complicated, for example, it is mentioned that each substance in the reaction mixture needs to reach a certain "static concentration" to ensure that the reaction can be smoothly carried out, and the "static concentration" refers to a fixed concentration that each substance in the reaction mixture needs to maintain when the reaction is smoothly carried out, and a certain time is needed to reach the requirement of the "static concentration" after the reaction is started; reaction mixtures need to be extracted from each cascade reactor in the reaction process, and the quantity of the extracted mixtures and the concentration of each component need to keep a certain proportional relation with the feeding quantity; in the process, materials need to stay in each reactor for waiting, the stay waiting time is different, and the materials do not flow continuously and are not continuous flow process; the same reactor is used for synthesizing fluoroethylene carbonate with different fluorination degrees, and the exothermic retention time of materials in the reactor is different. In addition, these process requirements all add to the overall process control difficulties and production site operational difficulties.

Chinese patent CN201080042843A relates to the synthesis of poly (difluoro, trifluoro and tetrafluoro) ethylene carbonate and corresponding mixtures using reactor cascade like the above, and the apparatus and process also have the above three problems, such as the need of material residence waiting in each reactor and different residence waiting time, and the same reactor in synthesizing fluoroethylene carbonate with different fluorination degree. In summary, although the above process and apparatus uses reactor cascade to realize continuous process, the reaction mixture still remains in the cascade reactor to wait and flows discontinuously, which is not a continuous flow process, and the reaction is not rapid, and the reaction time reaches more than 30 minutes.

Furthermore, the prior art processes, either batch or semi-continuous, or reactor-cascaded, inevitably have amplification effects, which bring about many uncertainties for further industrial applications. The Scaling up Effect (Scaling up Effect) refers to the research result obtained from the chemical process (i.e. small scale) experiment (e.g. laboratory scale) performed by small equipment, and the result obtained from the same operation condition is often very different from that obtained from the large scale production apparatus (e.g. industrial scale). The effect on these differences is called the amplification effect. The reason for this is mainly that the temperature, concentration, material residence time distribution in small-scale experimental facilities are different from those in large-scale facilities. That is, the results of the small scale experiments cannot be completely repeated on an industrial scale under the same operating conditions; to achieve the same or similar results on an industrial scale as in small scale experiments, process parameters and operating conditions need to be changed by optimal adjustment. For chemical processes, the amplification effect is a difficult and urgent problem to solve. If not solved, the production process and the product quality have great uncertainty, and firstly, the quality of downstream products is directly unstable and is difficult to control; secondly, the uncertainty can bring about the fluctuation of the technological parameters in the production process, so that the production process cannot be effectively controlled, the production safety cannot be ensured, and a plurality of potential safety hazards are buried in the production process.

In conclusion, the direct fluorination reaction has severe requirements on mass transfer, heat transfer, safety and the like of devices and processes, and is limited by the devices and the processes, and the prior art has the problems of complicated devices and complex processes at different degrees, so that the problems of overlong reaction time, low production efficiency, poor flexibility and poor selectivity of the processes and the devices are caused. Aiming at the synthesis of fluoroethylene carbonate with different fluorination degrees, a production process which can not only fully exert the reaction advantages of a direct fluorination method, but also overcome the three defects of the method is not developed at present, namely: the problems of heat transfer and mass transfer are fully solved, and the flexibility and selectivity of the difference of physical properties (such as melting point, thermal conductivity, heat capacity, solubility and the like) and reaction activity of different raw materials are also considered.

Disclosure of Invention

Aiming at the defects of the prior art, the technical problem to be solved by the invention is to provide a continuous flow synthesis process of fluoroethylene carbonate, which is rapid, flexible, efficient, safe and easy for mass production, and a device capable of realizing the process.

Aiming at huge heat release of direct fluorination reaction, process parameters matched with equipment materials and structures, physical and chemical properties of materials (raw materials, intermediates, products and the like) and a specific reaction process need to be designed and optimized in process development, the relationship between reaction heat release, system heat transfer and equipment heat exchange is balanced, and a large amount of reaction heat is removed in time on the premise of ensuring production safety and efficiency so as to prevent the reaction from being out of control due to over-high system overheat pressure. For example, the physical properties (e.g., melting point, thermal conductivity, heat capacity, solubility, etc.) and reactivity of different raw materials can vary widely, and process parameters need to be adjusted and optimized accordingly for specific raw materials and specific reaction processes. In order to flexibly adapt to the production requirements of different raw material feeds and fluorinated products with different degrees, process development needs to flexibly optimize reaction conditions and process parameters based on the reactivity of raw materials and intermediates, the produced target products and the reaction mechanism so as to match the reaction with the specific process and improve the selectivity of the corresponding target products. For gas-liquid two-phase heterogeneous reaction, the equipment structure and process parameters need to be optimized in process development to enhance the gas-liquid two-phase mixing effect and promote two-phase mass transfer, the mass transfer effect of the gas-liquid two-phase in the reactor is measured by adopting the specific surface area of gas/liquid dispersion, and the larger the specific surface area is, the better the mass transfer effect is. In addition, in addition to being greatly influenced by mass transfer factors, the fluorination reaction is also influenced by kinetic factors, which mainly include various physical and chemical factors (e.g., gas density, solubility, melting point, critical temperature, critical pressure, system temperature, system pressure, concentration, medium in the reaction system, catalyst, flow field and temperature field distribution, residence time distribution, etc.) and corresponding reaction mechanisms, i.e., the enhancement method according to the factors also has a promoting effect on the conversion rate and selectivity of the reaction.

The continuous synthesis process refers to the connection of production steps of a production system in the production process, and the continuous operation is guaranteed as a whole, but the stay waiting is allowed in each step. As a fast and efficient continuous process, the continuous-flow synthesis process has the characteristics of short time consumption, high efficiency, easy operation and the like, raw materials are continuously added in the process, and products are continuously produced and prepared, materials (namely reaction mixtures containing the raw materials, intermediates, products, solvents and the like) continuously flow in the process without interruption and stop waiting, namely the products are continuously produced, and the process is a flow line type chemical production process. When the process operation reaches a steady state, the state parameters of the material composition, the temperature and the like at any position in the reactor do not change along with the time, and the process is a steady state process, so the production process and the product quality are stable. In a process comprising multiple steps, if some of the steps are continuous or simply connected, the process may be referred to as a continuous process; a continuous flow process is only possible if all steps are continuous and the material flows continuously throughout the process, i.e. the feed is continuously added and the product is continuously obtained.

Based on the difference between the continuous flow process and the batch process and other continuous processes, the continuous flow process has very different control requirements and condition parameters compared with the process, and the batch process or other continuous process conditions of the same product cannot be used for reference or transplanted into the continuous flow process and need to be redesigned and developed. Continuous flow processes are therefore entirely new processes relative to batch and other continuous processes, and often continuous flow process conditions are not achievable in other processes.

Reaction time in a continuous process refers to the total time required from the entry of the feedstock into the reactor to the exit of the product from the reactor. The control requirements and condition parameters of the technological process are greatly different due to different reaction times in the continuous process, the technological conditions with long reaction time of the same product cannot be used for reference or transplanted to the process with short reaction time, the reaction time of the continuous process is shortened, and the technological process needs to be redesigned and developed. Thus, a short reaction time continuous process, especially a continuous flow process with a reaction time in seconds, is a completely new process compared to a long reaction time continuous process, and often continuous flow process conditions are not achievable in other processes.

In order to solve the technical problem, the invention adopts the following technical scheme:

a continuous flow synthesis process of fluoroethylene carbonate takes raw materials to be fluorinated and fluorine gas as raw materials, and fluoroethylene carbonate is obtained by continuously and sequentially carrying out mixing dispersion, fluorination reaction and gas-liquid separation steps, wherein a process route schematic diagram related to the continuous flow synthesis process is shown in figure 1.

As shown in FIG. 1, the continuous flow synthesis process of fluoroethylene carbonate and the corresponding integrated continuous flow reactor of the present invention can realize the following synthesis processes:

synthesizing one or more of monofluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate by taking ethylene carbonate as a raw material;

synthesizing difluoroethylene carbonate (any one or more of 4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate by taking monofluoroethylene carbonate as a raw material;

synthesizing any one or more of trifluoroethylene carbonate and tetrafluoroethylene carbonate by taking 4, 4-difluoroethylene carbonate and/or cis-4, 5-difluoroethylene carbonate and/or trans-4, 5-difluoroethylene carbonate as raw materials;

the tetrafluoroethylene carbonate is synthesized by taking trifluoroethylene carbonate as a raw material.

In the present context, the term "fluorine gas" is understood to mean elemental fluorine diluted or undiluted by an inert gas. Preferably, the fluorine gas of step (a) will be applied in the form of elemental fluorine dilution. Preferred diluents are inert gases, in particular selected from nitrogen, noble gases, or mixtures thereof. The mixed gas refers to a mixture of nitrogen and a rare gas, and the rare gas refers to a simple substance of an element in group 18 of the periodic table. A mixed gas of fluorine gas and nitrogen gas is preferable. The concentration of fluorine gas is more than 0% by volume. It is preferably equal to or greater than 5% by volume. More preferably equal to or greater than 12% by volume. The concentration of fluorine gas is preferably 25% by volume or less. Preferably, it is equal to or less than 18% by volume. Preferably, fluorine gas is contained in the gas mixture in the range of 12 to 18% by volume. Although it is possible to introduce into these different reactors different gas mixtures with different concentrations of elemental fluorine or with different inert gases, or diluted and undiluted fluorine, it is preferred for practical reasons to apply only one specific gas or gas mixture for all reactors.

The "degree of fluorination" as used herein means the number of fluorine atoms contained in the compound molecule, for example, the degree of fluorination of ethylene carbonate is 0, the degree of fluorination of monofluoroethylene carbonate is 1, the degree of fluorination of difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate) is 2, the degree of fluorination of trifluoroethylene carbonate is 3, and the degree of fluorination of tetrafluoroethylene carbonate is 4.

Wherein the starting material to be fluorinated is reacted in the liquid phase with elemental fluorine (F)₂) Reacting to form fluoroethylene carbonate, i.e. the degree of fluorination of the starting material to be fluorinated is less than and/or equal to that of the product, said starting material to be fluorinated being selected from: ethylene carbonate, monofluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate, tetrafluoroethylene carbonate, or a mixture of any two or more thereof.

The "fluoroethylene carbonate" described herein is selected from: one or more of monofluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate.

Preferably, the direct fluorination reaction is carried out in the presence of a suitable inert solvent which is a solvent which does not react with fluorine gas and which may be a linear or cyclic perfluorocarbon such as fluorinated ethers sold by Solvay Solexis, tetrafluoroethylene carbonate or hydrogen fluoride and the like. The starting material to be fluorinated may or may not comprise an inert solvent. Preferably, said to-be-fluorinated does not comprise an inert solvent.

The invention provides a process for quickly and continuously synthesizing fluoroethylene carbonate, which has strong universality and is realized by only one reactor, and the process comprises the following steps: the raw material to be fluorinated and the fluorine gas are continuously fed into the reactor and the reaction product is continuously collected. The fluoroethylene carbonate is selected from one or more of monofluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate. The reactor is an integrated continuous flow reactor, and the continuous flow reactor comprises three functional units: a mixing and dispersing unit, a fluorination reaction unit and a gas-liquid separation unit. By means of the optimization of the process condition settings such as temperature zone division, temperature and/or pressure and the like of the functional units and the synergistic effect of the three functional units, no additional post-treatment or purification step is needed in the process of the process, the total process time is shortened to within 10 minutes, and the process efficiency is greatly improved. Particularly, one reactor can be used for flexibly synthesizing fluoroethylene carbonate products with different degrees of fluorination and mixture products thereof only by simply adjusting process parameters, and target products with various degrees of fluorination can be synthesized with high selectivity, so that the process applicability is strong, and the industrial production can be more suitable for market demands.

The synthetic process of the fluoroethylene carbonate has no amplification effect, and the amplification reaction scale has no influence on the reaction conversion rate, the target product yield and the selectivity. The invention overcomes the defect of amplification effect in the preparation of fluoroethylene carbonate in the prior art, and is very suitable for industrial large-scale production.

The invention provides a rapid continuous flow synthesis process of fluoroethylene carbonate, which is characterized in that: the synthesis process takes a raw material to be fluorinated and fluorine gas as reactants, and the fluoroethylene carbonate is obtained by continuously and sequentially carrying out mixing dispersion, fluorination reaction and gas-liquid separation steps, the synthesis process is carried out in an integrated continuous flow reactor, the raw material to be fluorinated and the fluorine gas are uninterruptedly added into a feed inlet of the integrated continuous flow reactor, the fluoroethylene carbonate is obtained uninterruptedly at a discharge outlet of the integrated continuous flow reactor, and the reaction time is equal to or less than 600 s.

Further, the reaction time is 20-600 s, preferably 30-480 s, and more preferably 40-300 s.

Furthermore, the synthesis process has no amplification effect.

Further, the integrated continuous flow reactor comprises a mixing and dispersing unit, a fluorination reaction unit and a gas-liquid separation unit, wherein the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated or the inert solvent and the fluorine gas and dispersing the fluorine gas in a liquid phase, and then conveying the mixture to the fluorination reaction unit; or the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated and the fluorine gas, dispersing the fluorine gas in a liquid phase and simultaneously carrying out primary fluorination reaction, and then conveying the mixture to the fluorination reaction unit; the fluorination reaction unit is used for reacting a raw material to be fluorinated with fluorine gas to generate fluoroethylene carbonate and conveying the fluoroethylene carbonate to the gas-liquid separation unit; the gas-liquid separation unit is used for separating liquid from gas.

Further, in the mixing and dispersing unit, fluorine gas is only contacted with a raw material to be fluorinated or an inert solvent, is mixed and dispersed in a liquid phase, and then enters the fluorination reaction unit to carry out fluorination reaction; in the mixing and dispersing unit, fluorine gas and raw materials to be fluorinated are contacted, mixed and dispersed in a liquid phase, and simultaneously, the fluorine gas and the raw materials to be fluorinated perform a primary fluorination reaction and then enter the fluorination reaction unit to perform a further fluorination reaction.

Furthermore, the mixing and dispersing unit or the fluorination reaction unit further has the function of separating liquid from gas. Wherein, the gas after gas-liquid separation can be recycled and can also enter a tail gas treatment device.

Further, the synthesis process is carried out at a pressure equal to or greater than ambient pressure, preferably equal to or greater than 5bar, more preferably equal to or greater than 10bar, all relative pressures.

Further, the pressure of each cell may be the same or different.

Further, the synthesis process is carried out under gradient pressure, the pressure of the mixing and dispersing unit is greater than that of the fluorination reaction unit, and the pressure of the fluorination reaction unit is greater than that of the gas-liquid separation unit. The high pressure used in the pressure of the mixing and dispersing unit can increase the solubility of fluorine gas in a liquid phase, reduce the volume of a fluorine gas phase, and promote the gas-liquid two-phase mixing of raw materials to be fluorinated and the fluorine gas, which is beneficial to the fluorination reaction; the pressure of the fluorination reaction unit is lower than that of the mixing and dispersing unit, so that the solubility of hydrogen fluoride gas generated by the reaction in a liquid phase can be reduced, meanwhile, the pressure of the fluorination reaction unit cannot be too low to ensure the sufficient solubility of fluorine gas in the liquid phase, and the pressure adopted by the fluorination reaction unit can effectively promote the reaction until the two solubilities reach a balance; the gas-liquid separation unit applies lower pressure, further reduces the solubility of the hydrogen fluoride gas in the liquid phase, is convenient for gas-liquid separation after the reaction is finished, is favorable for reducing the residue of the hydrogen fluoride in the fluoroethylene carbonate product, and improves the product quality. Since the synthesis reaction of the present invention is a heterogeneous reaction, it is necessary to increase the solubility of fluorine gas in the liquid phase in order to accelerate the reaction, and on the other hand, it is necessary to decrease the solubility of hydrogen fluoride gas generated by the reaction in the liquid phase, and the gradient pressures formed by the mixing and dispersing unit, the fluorination reaction unit, and the gas-liquid separation unit cooperate with each other to achieve an optimum balance of the solubilities of fluorine gas and hydrogen fluoride gas in the liquid phase, thereby accelerating the reaction, achieving a sufficient reaction in a short time, and completing the reaction with high efficiency and high quality.

Further, the pressure of the mixing and dispersing unit is 5-18 bar, preferably 10-15 bar; the pressure of the fluorination reaction unit is 3-18 bar, preferably 5-15 bar; the pressure of the gas-liquid separation unit is 0-10 bar, preferably 2-7 bar.

Further, the number of the feeding holes of the integrated continuous flow reactor is 1 or more, and the number of the discharging holes of the integrated continuous flow reactor is 1 or more.

Further, each unit independently comprises more than one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the units are connected in series.

Furthermore, each unit corresponds to one temperature zone, each temperature zone independently comprises more than one reactor module or reactor module group, the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the temperature zones are connected in series.

Furthermore, the reactor modules, the reactor module groups and the reactor modules and the reactor module groups are respectively connected in series or in parallel.

Further, the reactor module is selected from any one of the reaction devices capable of realizing continuous flow process, preferably, the reaction device is selected from any one or more of Microreactor (Microreactor), serial-connected coil reactor (Tandem loop reactor) and Tubular reactor (Tubular reactor). The microreactor, also known as a microstructured reactor or microchannel reactor, is a device in which chemical reactions take place in a confined region having a prevalent lateral dimension of 1mm or less, most typically in the form of a microscale channel. The coil reactors are connected in series, namely the coil reactors are connected in series by pipelines, wherein the coil reactors are in the form of coils made of tubular reactors. Tubular reactors are a continuous operating reactor that has a tubular shape and a large length-diameter ratio that has emerged in the middle of the last century. Such reactors can be very long; the single tube can be connected in parallel or the multiple tubes can be connected in parallel; the tube can be empty or filled. Preferably, the reaction apparatus may be one or more.

Further, the reaction device is provided with a flow channel.

Further, the flow passage is made of refractory F₂And HF, preferably stainless steel, F-resistant₂Alloys with HF (gold Monel, Inconel, Hastelloy), polymeric materials (partially or perfluorinated polymers poly, alkylene polymers), other types of polymers (polytetrafluoroethylene, perfluoroalkoxyalkane copolymers), ceramics (silicon carbide) or coatings resistant to F₂And HF.

Further, the specific surface area of the flow channel is greater than or equal to 2000m²/m³Heat transfer coefficient greater than or equal to 1.5MW/m³K, gas/liquid dispersion specific surface area of 47000m or more²/m³. The flow channel has a large specific surface area (greater than or equal to 2000 m)²/m³) Can obtain a value of greater than or equal toAt 1.5MW/m³The heat transfer coefficient of K is high, and the heat transfer performance of the system is excellent; the materials are mixed forcibly in the whole flowing process along the flowing channel, and the specific surface area of gas/liquid dispersion can be up to 47000m²/m³And the gas-liquid two-phase mass transfer performance is excellent.

Further, the raw material to be fluorinated is selected from any one or more of ethylene carbonate, monofluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate, and the fluorination degree of the raw material to be fluorinated is less than or equal to that of the product fluoroethylene carbonate.

Further, the raw material to be fluorinated comprises an inert solvent, which is a solvent that does not chemically react with fluorine gas.

Further, the inert solvent is selected from any one or more of linear or cyclic perfluorocarbons, preferably fluorinated ether, tetrafluoroethylene carbonate and hydrogen fluoride.

Further, the fluoroethylene carbonate is selected from any one or any plurality of fluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate.

Further, the synthesis process may be carried out in the absence of an inert solvent.

Further, the continuous flow synthesis process is carried out in an integrated continuous flow reactor comprising 3 temperature zones, the mixing and dispersing unit corresponds to the temperature zone 1, the fluorination reaction unit corresponds to the temperature zone 2, the gas-liquid separation unit corresponds to the temperature zone 3, and the continuous flow synthesis process comprises the following steps:

(a) the method comprises the steps of (1) contacting and mixing a raw material to be fluorinated or an inert solvent with fluorine gas in a temperature zone 1, dispersing the fluorine gas in a liquid phase, and then conveying the mixture to a temperature zone 2; or the raw material to be fluorinated and fluorine gas are contacted and mixed in the temperature region 1, the fluorine gas is dispersed in the liquid phase, and the primary fluorination reaction is carried out at the same time, and then the mixture is conveyed to the temperature region 2;

(b) reacting a raw material to be fluorinated with fluorine gas in a temperature zone 2 to generate fluoroethylene carbonate, and conveying a reaction mixture to a temperature zone 3;

(c) the reaction mixture enters the temperature zone 3 for gas and liquid separation.

Further, the temperature of the temperature zone 1 is-40 to 20 ℃, and preferably-20 to 10 ℃.

Further, the temperature of the temperature zone 2 is 10-100 ℃, preferably 30-80 ℃, and more preferably 40-60 ℃.

Further, the temperature of the temperature zone 3 is 30-80 ℃, preferably 40-60 ℃.

Further, the synthesis process is carried out at a pressure equal to or greater than ambient pressure, preferably at a pressure equal to or greater than 5bar, more preferably at a pressure equal to or greater than 10 bar.

Further, the pressure of each temperature zone may be the same or different.

Further, the synthesis process is carried out under gradient pressure, the pressure of the temperature zone 1 is greater than that of the temperature zone 2, and the pressure of the temperature zone 2 is greater than that of the temperature zone 3. The gradient pressure of the three temperature zones is cooperated, so that the optimal balance of the solubility of fluorine gas and hydrogen fluoride gas in a liquid phase is achieved, the reaction is promoted, the full reaction is realized in a short time, and the reaction is finished with high efficiency and high quality. Preferably, the synergistic effect of the temperature distribution of the three temperature zones is further combined, and the reaction is completed with higher efficiency and high quality.

Further, the pressure of the temperature zone 1 is 5-18 bar, preferably 10-15 bar; the pressure of the temperature zone 2 is 3-18 bar, preferably 5-15 bar; the pressure in the temperature zone 3 is 0-10 bar, preferably 2-7 bar.

Further, the fluorine gas is elemental fluorine diluted or not with an inert gas, the inert gas is selected from nitrogen, a rare gas, or a mixed gas thereof, the mixed gas is a mixture of nitrogen and a rare gas, and the rare gas is an elemental fluorine of an element in group 18 of the periodic table. The fluorine gas is preferably a mixed gas of elemental fluorine and nitrogen gas.

Further, the concentration of elemental fluorine in the fluorine gas is more than 0%, preferably equal to or more than 5%, more preferably equal to or more than 12% by volume; the concentration of elemental fluorine in the fluorine gas is preferably 25% by volume or less, preferably 18% by volume or less, and most preferably, the concentration of elemental fluorine in the fluorine gas is 12% to 18%.

It must be noted that for the linkage between C-H and F₂One molecule of HF is formed for each C-F bond formed during the reaction of (a). Thus, it is assumed that Ethylene Carbonate (EC) and fluorine (F)₂) Is a stoichiometric reaction between, then F is required₂The ratio EC is 4, i.e. if 1 mol of ethylene carbonate is used as starting material to be fluorinated, 4 mol of F are stoichiometrically required₂To achieve complete fluorination of the ethylene carbonate. Therefore, in the present invention, for the sake of simplicity of the presentation, F is specified₂The ratio of/H represents: f corresponding to each H atom to be substituted to form a C-F bond in the starting material to be fluorinated₂I.e. F for each H atom to be subjected to fluorine substitution₂The number of equivalents of (c). That is, F₂The equivalent ratio to the starting material to be fluorinated being the number of H atoms to be substituted multiplied by F₂The ratio/H, e.g. trifluoroethylene carbonate from Ethylene Carbonate (EC), using F₂With a ratio of 1.15:1, since the number of H atoms to be substituted is 3, then F₂Equivalent ratio F to starting material to be fluorinated₂the/EC was 3.45: 1.

Further, said F₂The ratio of H to H is 1.0 to 2.0:1, preferably 1.05 to 1.50:1, more preferably 1.10 to 1.25: 1.

The method of the invention synthesizes fluoroethylene carbonate in a rapid and high-pass manner, wherein the fluoroethylene carbonate is selected from any one or more of fluoroethylene carbonate, difluoroethylene carbonate (4, 4-difluoroethylene carbonate, cis-4, 5-difluoroethylene carbonate, trans-4, 5-difluoroethylene carbonate), trifluoroethylene carbonate and tetrafluoroethylene carbonate. In preferred embodiments, the selective production of any one or any plurality of monofluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate, and tetrafluoroethylene carbonate is possible.

The continuous flow synthesis process has good flexibility and strong universality, can quickly and continuously synthesize fluoroethylene carbonate by only using one reactor, and can synthesize target products with various degrees of fluorination in a high-selectivity manner. Preferably, the reaction conversion rate of the synthesis process is more than 90%, more preferably, the reaction conversion rate is more than 95%; the yield of fluoroethylene carbonate is 85% or more, and more preferably 90% or more.

It should be noted that the fluorine gas concentration used in the actual synthesis (including in the laboratory, pilot plant, actual production process) has a deviation of the volume concentration of ± 3 percentage points; f₂The ratio/H has a deviation of + -0.05; the temperature of the temperature zone has deviation of +/-5 ℃; the temperature zone pressure has deviation of +/-1 bar; the reaction time may vary by. + -. 10 s.

The second purpose of the invention is to provide an integrated reactor special for a rapid continuous synthesis process of fluoroethylene carbonate, and the invention develops the special integrated reactor to meet the conditions of the continuous process. The reactor can be of a modular structure, the organization mode and the number of modules and the modules contained in each temperature zone need to be designed, and targeted process conditions and parameters need to be developed, wherein the process conditions and the parameters comprise the division and the temperature setting of each temperature zone, the setting of pressure and the cooperative setting of pressure and temperature, and the various factors have comprehensive synergistic action, so that the continuous process is realized. And the temperature, the material concentration, the material ratio and the material flow rate can be further combined to be matched with the reaction process, so that a better reaction effect is obtained. The material comprises raw materials and intermediate products in the reaction process, the material concentration comprises the concentration of the raw materials and the concentration of the intermediate products, the material ratio comprises the ratio of the raw materials and the concentration of the intermediate products, and the material flow rate comprises the flow rate of the raw materials and the flow rate of the intermediate products.

The invention relates to an integrated reactor special for a continuous flow synthesis process of fluoroethylene carbonate, which adopts a modular structure and comprises a mixing and dispersing unit, a fluorination reaction unit and a gas-liquid separation unit, wherein the mixing and dispersing unit is used for contacting and mixing a raw material to be fluorinated or an inert solvent with fluorine gas, dispersing the fluorine gas in a liquid phase, and then conveying the mixture to the fluorination reaction unit; or the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated and the fluorine gas, dispersing the fluorine gas in a liquid phase and simultaneously carrying out primary fluorination reaction, and then conveying the mixture to the fluorination reaction unit; the fluorination reaction unit is used for reacting a raw material to be fluorinated with fluorine gas to generate fluoroethylene carbonate and conveying the fluoroethylene carbonate to the gas-liquid separation unit; the gas-liquid separation unit is used for separating liquid from gas.

Furthermore, the mixing and dispersing unit or the fluorination reaction unit further has the function of separating liquid from gas.

Further, the number of the feeding holes of the integrated continuous flow reactor is 1 or more, and the number of the discharging holes of the integrated continuous flow reactor is 1 or more.

Further, each unit independently comprises more than one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the units are connected in series.

Furthermore, each unit corresponds to one temperature zone, each temperature zone independently comprises more than one reactor module or reactor module group, the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the temperature zones are mutually connected in series.

Furthermore, the reactor modules, the reactor module groups and the reactor modules and the reactor module groups are respectively connected in series or in parallel.

Further, the reactor module is optionally selected from any one or more of a reaction device capable of realizing a continuous flow process, preferably, the reaction device is selected from any one or more of a microreactor, a serial coil reactor and a tubular reactor. Preferably, the reaction apparatus may be one or more.

Further, the reaction device is provided with a flow channel.

Further, the specific surface area of the flow channel is greater than or equal to 2000m²/m³Heat transfer coefficient greater than or equal to 1.5MW/m³K, gas/liquid dispersion specific surface area of 47000m or more²/m³。

Further, the flow passage is made of refractory F₂And HF, preferably stainless steel, F-resistant₂Alloys with HF (gold Monel, Inconel, Hastelloy), polymeric materials (partially or perfluorinated polymers poly, alkylene polymers), other types of polymers (polytetrafluoroethylene, perfluoroalkoxyalkane copolymers), ceramics (silicon carbide) or coatings resistant to F₂And HF.

Preferably, the mixing and dispersing unit corresponds to a temperature zone 1, the fluorination reaction unit corresponds to a temperature zone 2, and the gas-liquid separation unit corresponds to a temperature zone 3.

Compared with the prior art, the invention has the following beneficial effects:

1. the high-efficiency continuous flow synthesis of fluoroethylene carbonate is realized on the integrated continuous flow reactor. That is, reactants are continuously fed into the reactor, and reaction products are continuously collected without additional post-treatment or purification steps in the process. By means of the arrangement of gradient pressure and the division of different temperature areas, the efficiency of the process is greatly improved. The reaction time is at most 10 minutes.

2. The process of the present invention allows the selective production of any one or any plurality of monofluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate, tetrafluoroethylene carbonate in a rapid and highly versatile manner. The process selectivity is good, the device flexibility is strong, a reactor can be used for flexibly synthesizing a plurality of fluoroethylene carbonate products with different degrees of fluorination and mixture products thereof only by simply adjusting process parameters, the process and the device applicability is strong, and the industrial production can be more suitable for market demands.

3. The process safety is greatly improved, and the relatively small liquid holdup and excellent heat and mass transfer characteristics of the continuous flow reactor are combined with the short reaction time (within 10 minutes), so that the process is safer. Wherein the liquid holdup of the reactor is the total volume of the reaction mass present in the reactor at any one time when the operation reaches steady state.

4. The fluorination reaction as a gas-liquid two-phase reaction requires an increase in gas-liquid two-phase contact to promote the reaction, and in the prior art process, in order to achieve a suitable yield, the flow rate of the raw material needs to be reduced or the raw material needs to be circulated for a plurality of times to increase the probability of gas-liquid two-phase contact, thereby prolonging the reaction time, but obviously reducing the efficiency of the fluorination reaction. The technological process of the invention can be carried out under gradient pressure, the pressure of the mixing and dispersing unit is greater than that of the fluorination reaction unit, and the pressure of the fluorination reaction unit is greater than that of the gas-liquid separation unit. The high pressure used by the pressure of the mixing and dispersing unit can increase the solubility of the fluorine gas in the liquid phase, reduce the volume of the gas phase of the fluorine gas and promote the gas-liquid two-phase mixing of the raw material to be fluorinated and the fluorine gas, which is beneficial to the fluorination reaction; the pressure of the fluorination reaction unit is lower than that of the mixing and dispersing unit, so that the solubility of hydrogen fluoride gas generated by the reaction in a liquid phase can be reduced, meanwhile, the pressure of the fluorination reaction unit cannot be too low to ensure the sufficient solubility of fluorine gas in the liquid phase, and the pressure adopted by the fluorination unit can effectively promote the reaction until the two solubilities reach a balance; the gas-liquid separation unit applies lower pressure, further reduces the solubility of the hydrogen fluoride gas in the liquid phase, is convenient for gas-liquid separation after the reaction is finished, is favorable for reducing the residue of the hydrogen fluoride in the fluoroethylene carbonate product, and improves the product quality. Since the synthesis reaction of the present invention is a heterogeneous reaction, it is necessary to increase the solubility of fluorine gas in the liquid phase in order to accelerate the reaction, and on the other hand, it is necessary to decrease the solubility of hydrogen fluoride gas generated by the reaction in the liquid phase, and the gradient pressures formed by the mixing and dispersing unit, the fluorination reaction unit, and the gas-liquid separation unit cooperate with each other to achieve an optimum balance of the solubilities of fluorine gas and hydrogen fluoride gas in the liquid phase, thereby accelerating the reaction, achieving a sufficient reaction in a short time, and completing the reaction with high efficiency and high quality.

5. In the process, the reaction speed is accelerated by temperature zone division and gradient pressure setting, and the reaction time is shortened. The solubility of the fluorine gas in a liquid phase is increased by matching low temperature with high pressure in the mixing and dispersing unit, and simultaneously, the concentration of the fluorine gas in unit volume of the reactor is increased by high pressure, so that the mixed mass transfer of the raw material to be fluorinated and the fluorine gas is promoted, the high conversion rate of 95 percent and the yield of 90 percent can be obtained, the reaction time is greatly shortened, the reaction can be completed within 10 minutes usually, and the production is more efficient.

6. Three functional units are designed in an integrated continuous flow reactor according to the mass transfer and kinetic requirements of the fluorination reaction and the physical and chemical properties of the raw materials used, including the raw material to be fluorinated and fluorine gas. Wherein the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated or the inert solvent with the fluorine gas, dispersing the fluorine gas in a liquid phase, and then conveying the mixture to the fluorination reaction unit; or the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated and the fluorine gas, dispersing the fluorine gas in a liquid phase and simultaneously carrying out primary fluorination reaction, and then conveying the mixture to the fluorination reaction unit; the fluorination reaction unit is used for reacting a raw material to be fluorinated with fluorine gas to generate fluoroethylene carbonate and conveying the fluoroethylene carbonate to the gas-liquid separation unit; the gas-liquid separation unit is used for separating liquid from gas. The three functional units act synergistically, so that the reaction can be completed in 10 minutes or even shorter time. Only one reactor is needed to complete the reaction process, and the integration degree is high.

7. In the integrated continuous flow reactor, the product quality is stable and the reproducibility is good because the flow rate is stable and the production process is stable.

8. The process still completes the reaction within 10 minutes on an industrial scale, the product content and the yield are basically the same as those of the process on a laboratory scale, no amplification effect is found, and the problem of industrial amplification of the fluoroethylene carbonate continuous flow process is solved.

9. The reactor can meet the strict requirements of fluorination reaction on mass transfer, heat transfer, safety, corrosion resistance and the like of devices and processes without additional cooling or gas dispersion adjusting equipment, and has the advantages of simple process operation, energy conservation, high integration degree, small volume, small occupied area and great saving of plant land.

Drawings

FIG. 1 is a schematic diagram of a continuous flow synthesis process of fluoroethylene carbonate according to the present invention;

FIG. 2 is a schematic view of an integrated reactor according to the present invention.

Wherein, the temperature of the temperature zone 1 is T1; the temperature of the temperature zone 2 is T2; the temperature of the temperature zone 3 is T3.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

Fluoroethylene carbonate example:

in this embodiment, the concentrations of the raw materials to be fluorinated are mass concentrations, the concentrations of the fluorine in the fluorine gas are volume concentrations, and the purity of the product is detected by a Gas Chromatography (GC).

Wherein, the temperature of the temperature zone 1 is T1; the temperature of the temperature zone 2 is T2; the temperature of the temperature zone 3 is T3.

Raw material 1 (ethylene carbonate) was fed by a constant flow pump, and raw material 2 (20% F)₂And 80% N₂Mixed gas) is introduced through a pipeline, and the mixed gas are in contact with each other in the temperature zone 1, and fully mixed and primarily reacted through the temperature zone 1. The mixture flowing out of the temperature zone 1 enters the temperature zone 2 and flows through the temperature zone 2 to perform fluorination reaction on the corresponding fluoroethylene carbonate until the reaction is completed. The reaction liquid flowing out of the temperature zone 2 enters the temperature zone 3 for gas-liquid separation to obtain reaction mother liquid containing the fluoroethylene carbonate. And collecting reaction mother liquor. Distilling the mother liquor, cooling and the like to obtain the monofluoroethylene carbonate. The reaction parameters and results are as follows:

mean value

Examples 2 to 6

Using the procedure of example 1, the preparation of monofluoroethylene carbonate under different reaction parameters was examined, and the conditions of the parameters and the results are shown in the following table.

Mean value

Examples 7 to 11

The procedure of example 1 was followed to examine the preparation of difluoroethylene carbonate under different reaction parameters, the conditions of the parameters and the results are shown in the following table.

Mean value

Examples 12 to 14

Using the procedure of example 1, the preparation of trifluoroethylene carbonate under different reaction parameters was examined, and the conditions of the parameters and the results are shown in the following table.

Mean value

Examples 15 to 18

The procedure of example 1 was followed to examine the preparation of tetrafluoroethylene carbonate under different reaction parameters, the conditions of the parameters and the results are shown in the following table.

Mean value

Claims (45)

1. A rapid continuous flow synthesis process of fluoroethylene carbonate is characterized in that: the synthesis process takes a raw material to be fluorinated and fluorine gas as reactants, and the fluoroethylene carbonate is obtained by continuously and sequentially carrying out mixing dispersion, fluorination reaction and gas-liquid separation steps, the synthesis process is carried out in an integrated continuous flow reactor, the raw material to be fluorinated and the fluorine gas are uninterruptedly added into a feed inlet of the integrated continuous flow reactor, the fluoroethylene carbonate is obtained uninterruptedly at a discharge outlet of the integrated continuous flow reactor, and the reaction time is equal to or less than 600 s.
2. The continuous-flow synthesis process of claim 1, wherein: the reaction time is 20-600 s, preferably 30-480 s, and more preferably 40-300 s.
3. The continuous flow synthesis process according to claim 1 or 2, wherein: the synthesis process has no amplification effect.
4. The continuous-flow synthesis process according to any one of claims 1 to 3, wherein: the integrated continuous flow reactor comprises a mixing and dispersing unit, a fluorination reaction unit and a gas-liquid separation unit, wherein the mixing and dispersing unit is used for contacting and mixing raw materials to be fluorinated or inert solvents with fluorine gas, dispersing the fluorine gas in a liquid phase and then conveying the mixture to the fluorination reaction unit; or the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated and the fluorine gas, dispersing the fluorine gas in a liquid phase and simultaneously carrying out primary fluorination reaction, and then conveying the mixture to the fluorination reaction unit; the fluorination reaction unit is used for reacting a raw material to be fluorinated with fluorine gas to generate fluoroethylene carbonate and conveying the fluoroethylene carbonate to the gas-liquid separation unit; the gas-liquid separation unit is used for separating liquid from gas.
5. The continuous-flow synthesis process of claim 4, wherein: the mixing and dispersing unit or the fluorination reaction unit further has the function of separating liquid from gas.
6. The continuous-flow synthesis process according to any one of claims 1 to 5, wherein: the synthesis process is carried out at a pressure equal to or greater than ambient pressure, preferably equal to or greater than 5bar, more preferably equal to or greater than 10bar, both relative pressures.
7. The continuous-flow synthesis process of claim 6, wherein: the pressure of each cell may be the same or different.
8. The continuous-flow synthesis process of claim 6, wherein: the synthesis process is carried out under gradient pressure, the pressure of the mixing and dispersing unit is greater than that of the fluorination reaction unit, and the pressure of the fluorination reaction unit is greater than that of the gas-liquid separation unit.
9. The continuous-flow synthesis process of claim 6, wherein: the pressure of the mixing and dispersing unit is 5-18 bar, preferably 10-15 bar; the pressure of the fluorination reaction unit is 3-18 bar, preferably 5-15 bar; the pressure of the gas-liquid separation unit is 0-10 bar, preferably 2-7 bar.
10. The continuous-flow synthesis process according to any one of claims 1 to 9, wherein: the number of the feeding holes of the integrated continuous flow reactor is 1 or more, and the number of the discharging holes of the integrated continuous flow reactor is 1 or more.
11. The continuous-flow synthesis process according to any one of claims 1 to 10, wherein: each unit in the mixing and dispersing unit, the fluorination reaction unit and the gas-liquid separation unit independently comprises more than one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the units are mutually connected in series.
12. The continuous-flow synthesis process according to any one of claims 1 to 10, wherein: each unit in the mixed dispersion unit, the fluorination reaction unit and the gas-liquid separation unit corresponds to one temperature zone, each temperature zone independently comprises more than one reactor module or reactor module group, the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the temperature zones are connected in series.
13. The continuous-flow synthesis process according to any one of claims 10 to 12, wherein: the reactor modules, the reactor module groups and the reactor modules and the reactor module groups are respectively connected in series or in parallel.
14. The continuous-flow synthesis process according to any one of claims 11-13, wherein: the reactor module is selected from any one of reaction devices capable of realizing continuous flow process, preferably, the reaction device is selected from any one or more of a microreactor, a serial-connection coil reactor and a tubular reactor.
15. The continuous-flow synthesis process of claim 14, wherein: the reaction device is one or more.
16. The continuous-flow synthesis process according to claim 14 or 15, wherein: the reaction device is provided with a flow channel.
17. The continuous-flow synthesis process of claim 16, wherein: the specific surface area of the flow channel is greater than or equal to 2000m²/m³Heat transfer coefficient greater than or equal to 1.5MW/m³K, gas/liquid dispersion specific surface area of 47000m or more²/m³。
18. The continuous-flow synthesis process of claim 16, wherein: the flow passage is made of refractory F₂And HF, preferably stainless steel, F-resistant₂Alloys with HF (gold Monel, Inconel, Hastelloy), polymeric materials (partially or perfluorinated polymers poly, alkylene polymers), other types of polymers (polytetrafluoroethylene, perfluoroalkoxyalkane copolymers), ceramics (silicon carbide) or coatings resistant to F₂And HF.
19. The continuous-flow synthesis process according to any one of claims 1 to 18, wherein: the raw material to be fluorinated is selected from any one or more of ethylene carbonate, monofluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate and tetrafluoroethylene carbonate, and the fluorination degree of the raw material to be fluorinated is less than or equal to that of the product fluoroethylene carbonate.
20. The continuous-flow synthesis process of claim 19, wherein: the raw material to be fluorinated comprises an inert solvent, wherein the inert solvent is a solvent which does not chemically react with fluorine gas.
21. The continuous-flow synthesis process of claim 20, wherein: the inert solvent is selected from any one or more of linear or cyclic perfluorocarbons, preferably fluorinated ether, tetrafluoroethylene carbonate and hydrogen fluoride.
22. The continuous-flow synthesis process according to any one of claims 1 to 21, wherein: the fluoroethylene carbonate is selected from one or more of monofluoroethylene carbonate, difluoroethylene carbonate, trifluoroethylene carbonate and tetrafluoroethylene carbonate.
23. The continuous-flow synthesis process according to any one of claims 1 to 22, wherein: the synthesis process may be carried out in the absence of an inert solvent.
24. The continuous-flow synthesis process according to any one of claims 1 to 23, wherein: the continuous flow synthesis process is carried out in an integrated continuous flow reactor comprising 3 temperature zones, the mixing and dispersing unit corresponds to the temperature zone 1, the fluorination reaction unit corresponds to the temperature zone 2, the gas-liquid separation unit corresponds to the temperature zone 3, and the continuous flow synthesis process comprises the following steps:

    (a) the method comprises the steps of (1) contacting and mixing a raw material to be fluorinated or an inert solvent with fluorine gas in a temperature zone 1, dispersing the fluorine gas in a liquid phase, and then conveying the mixture to a temperature zone 2; or the raw material to be fluorinated and fluorine gas are contacted and mixed in the temperature region 1, the fluorine gas is dispersed in the liquid phase, and the primary fluorination reaction is carried out at the same time, and then the mixture is conveyed to the temperature region 2;

    (b) reacting a raw material to be fluorinated with fluorine gas in a temperature zone 2 to generate fluoroethylene carbonate, and conveying a reaction mixture to a temperature zone 3;

    (c) the reaction mixture enters the temperature zone 3 for gas and liquid separation.
25. The continuous-flow synthesis process of claim 24, wherein: the temperature of the temperature zone 1 is-40 to 20 ℃, and preferably-20 to 10 ℃.
26. The continuous-flow synthesis process of claim 24, wherein: the temperature of the temperature zone 2 is 10-100 ℃, preferably 30-80 ℃, and more preferably 40-60 ℃.
27. The continuous-flow synthesis process of claim 24, wherein: the temperature of the temperature zone 3 is 30-80 ℃, and preferably 40-60 ℃.
28. The continuous-flow synthesis process according to any one of claims 23-27, wherein: the synthesis process is carried out at a pressure equal to or greater than ambient pressure, preferably equal to or greater than 5bar, more preferably equal to or greater than 10 bar.
29. The continuous-flow synthesis process according to any one of claims 23-27, wherein: the pressure of each temperature zone can be the same or different.
30. The continuous-flow synthesis process according to any one of claims 23-27, wherein: the synthesis process is carried out under gradient pressure, the pressure of the temperature zone 1 is greater than that of the temperature zone 2, and the pressure of the temperature zone 2 is greater than that of the temperature zone 3.
31. The continuous-flow synthesis process according to any one of claims 23-27, wherein: the pressure of the temperature zone 1 is 5-18 bar, preferably 10-15 bar; the pressure of the temperature zone 2 is 3-18 bar, preferably 5-15 bar; the pressure in the temperature zone 3 is 0-10 bar, preferably 2-7 bar.
32. The continuous-flow synthesis process according to any one of claims 1 to 31, wherein: the fluorine gas is a fluorine simple substance diluted by inert gas or not diluted by the inert gas, the inert gas is selected from nitrogen, rare gas or mixed gas thereof, the mixed gas is a mixture of nitrogen and the rare gas, and the rare gas is a simple substance of 18 group elements in the periodic table of elements; the fluorine gas is preferably a mixed gas of elemental fluorine and nitrogen gas.
33. The continuous-flow synthesis process according to any one of claims 1 to 32, wherein: the concentration of the elemental fluorine in the fluorine gas is more than 0%, preferably 5% or more, more preferably 12% or more by volume; the concentration of elemental fluorine in the fluorine gas is preferably 25% by volume or less, preferably 18% by volume or less, and most preferably, the concentration of elemental fluorine in the fluorine gas is 12% to 18%.
34. The continuous-flow synthesis process according to any one of claims 1 to 32, wherein: f₂A ratio of/H is 1.0 to 2.0:1, preferably 1.05 to 1.50:1, more preferably 1.10 to 1.25:1, and the F₂The ratio of/H means: f corresponding to each H atom to be substituted to form a C-F bond in the starting material to be fluorinated₂The number of molecules of (a).
35. An integrated reactor dedicated to the continuous flow synthesis process of any one of claims 1 to 34, wherein: the integrated reactor adopts a modular structure and comprises a mixing and dispersing unit, a fluorination reaction unit and a gas-liquid separation unit, wherein the mixing and dispersing unit is used for contacting and mixing raw materials to be fluorinated or inert solvents with fluorine gas, dispersing the fluorine gas in a liquid phase and then conveying the mixture to the fluorination reaction unit; or the mixing and dispersing unit is used for contacting and mixing the raw material to be fluorinated and the fluorine gas, dispersing the fluorine gas in a liquid phase and simultaneously carrying out primary fluorination reaction, and then conveying the mixture to the fluorination reaction unit; the fluorination reaction unit is used for reacting a raw material to be fluorinated with fluorine gas to generate fluoroethylene carbonate and conveying the fluoroethylene carbonate to the gas-liquid separation unit; the gas-liquid separation unit is used for separating liquid from gas.
36. The continuous-flow synthesis process of claim 35, wherein: the mixing and dispersing unit or the fluorination reaction unit further has the function of separating liquid from gas.
37. The integrated reactor of claim 35 or 36, wherein: the number of the feeding holes of the integrated continuous flow reactor is 1 or more, and the number of the discharging holes of the integrated continuous flow reactor is 1 or more.
38. The continuous-flow synthesis process of any one of claims 35-37, wherein: each unit in the mixing and dispersing unit, the fluorination reaction unit and the gas-liquid separation unit independently comprises more than one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the units are mutually connected in series.
39. The continuous-flow synthesis process of any one of claims 35-37, wherein: each unit in the mixed dispersion unit, the fluorination reaction unit and the gas-liquid separation unit corresponds to one temperature zone, each temperature zone independently comprises more than one reactor module or reactor module group, the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel, and the temperature zones are connected in series.
40. The integrated reactor of any one of claims 35-39, wherein: the reactor modules, the reactor module groups and the reactor modules and the reactor module groups are respectively connected in series or in parallel.
41. The integrated reactor of any one of claims 35-40, wherein: the reactor module is selected from any one of reaction devices capable of realizing continuous flow process, preferably, the reaction device is selected from any one or more of a microreactor, a serial-connection coil reactor and a tubular reactor.
42. The integrated reactor of claim 41, wherein: the reaction device is one or more.
43. The continuous-flow synthesis process of claim 41 or 42, wherein: the reaction device is provided with a flow channel.
44. The continuous-flow synthesis process of claim 43, wherein: the specific surface area of the flow channel is greater than or equal to 2000m²/m³Heat transfer coefficient greater than or equal to 1.5MW/m³K, gas/liquid dispersion specific surface area of 47000m or more²/m³。
45. The continuous-flow synthesis process of claim 43, wherein: the flow passage is made of refractory F₂And HF, preferably stainless steel, F-resistant₂Alloys with HF (gold Monel, Inconel, Hastelloy), polymeric materials (partially or perfluorinated polymers poly, alkylene polymers), other types of polymers (polytetrafluoroethylene, perfluoroalkoxyalkane copolymers), ceramics (silicon carbide) or coatings resistant to F₂And HF.

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