Method for synthesizing chloroethylene carbonate through continuous microchannel

Abstract

The invention belongs to the technical field of fine chemical synthesis, and discloses a continuous micro-channel chloroethylene carbonate synthesis method, which comprises: 1, introducing a gas-state reactant into a first pipe through a gas inlet, and introducing a liquid-state reactant into the first pipe through a liquid inlet; 2, the gaseous reactant pushes the liquid reactant to enter the reaction tube of the reactor from the first tube, and a reaction is carried out under the condition that the ultraviolet lamp tube emits ultraviolet light and irradiates the reaction tube, and a gas-liquid mixture containing a target product is obtained; and 3, enabling the gas-liquid mixture to flow through a gas-liquid confluence inlet and a gas-liquid confluence outlet of a confluence device, and finally introducing the gas-liquid mixture into a gas-liquid separator for gas-liquid separation to obtain a target product. The method is simple to operate, safe and efficient, an amplification effect does not exist, and the prepared chloroethylene carbonate product is stable in quality, relatively high in yield and easy for industrial large-scale continuous production.

Description

Technical Field

[0001] The present application relates to the technical field of fine chemical synthesis, and in particular to a method for continuously microchannel synthesizing chloroethylene carbonate. Background Art

[0002] As an important electrolyte additive, chloroethylene carbonate effectively inhibits the decomposition of the electrolyte and improves the cycle performance and safety of the battery. It can improve the transmission efficiency of lithium ions between electrodes, reduce the internal resistance of the battery, and improve the charging and discharging efficiency and power performance of the battery. For high-energy-density lithium-ion batteries, the addition of chloroethylene carbonate helps to improve the overall performance of the battery and meet the needs of electric vehicles, energy storage and other fields for long battery life and high reliability. In addition, it can also be used to prepare lithium battery electrolyte additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC), and is an organic synthesis intermediate for pesticides and medicines, with broad application prospects.

[0003] At present, there are two main synthesis processes for chloroethylene carbonate:

[0004] One is to use ethylene carbonate and sulfuryl chloride as raw materials to prepare ethylene chlorocarbonate under the action of an initiator or an organic solvent. This method is relatively mild in terms of reaction temperature, pressure and other conditions, but the product purification is difficult, the reaction product is strongly acidic, the impurity content is high, and the subsequent purification process is complicated, which increases production costs and operational difficulties. At the same time, this process will produce a large amount of waste water and waste gas during the reaction process, which is more environmentally polluting. At present, the synthesis process using sulfuryl chloride as the chlorine source is mainly based on an intermittent process, which seriously affects production efficiency, and this process has been eliminated.

[0005] One is to use ethylene carbonate and chlorine as raw materials, and use ultraviolet light and other initiators to induce the reaction to synthesize chloroethylene carbonate, but the reaction stability is poor, the process is difficult to control, and the production equipment requirements are high. At the same time, the total reaction time of the existing process is long, and the formation of by-products or other impurities cannot be suppressed, resulting in poor product quality and low yield, which leads to bottlenecks in industrial-scale production. However, chlorine is a common and cheap chemical raw material compared to sulfuryl chloride, making the overall production cost relatively low.

[0006] Therefore, it is extremely important to find a continuous production process that is safe, efficient, easy to mass produce and has no scale-up effect.

[0007] The problem to be solved by the present application is: how to provide a process for the continuous production of chloroethylene carbonate which is safe, efficient, easy for large-scale production and has no scale-up effect. Summary of the invention

[0008] The purpose of the present application is to provide a method for continuously synthesizing chloroethylene carbonate from ethylene carbonate as a raw material by using microchannel reaction technology. The method is simple to operate, safe, and efficient, has no amplification effect, and the chloroethylene carbonate product obtained has stable quality and high yield, and is easy to be continuously produced on an industrial scale.

[0009] To achieve the above-mentioned purpose, the present application discloses a method for synthesizing chloroethylene carbonate in a continuous microchannel, and the method relates to a device for synthesizing chloroethylene carbonate, the device comprising a gas-liquid mixing module, a reactor, a flow collector, and a gas-liquid separator which are connected in sequence; the gas-liquid mixing module comprises a first tube, a side of the first tube is provided with a gas inlet and a liquid inlet, and the gas inlet is arranged at the front end of the liquid inlet; the reactor comprises a shell, a plurality of reaction tubes arranged inside the shell, and a plurality of ultraviolet lamps arranged inside the shell; the flow collector is provided with a gas-liquid confluence inlet and a gas-liquid confluence outlet, and the number of the gas-liquid confluence inlets corresponds to the number of the reaction tubes; the first tube, the reaction tube, the gas-liquid confluence inlet, and the gas-liquid confluence outlet are connected in sequence;

[0010] The method comprises the following steps:

[0011] Step 1: Pass the gaseous reactant into the first tube from the gas inlet, and pass the liquid reactant into the first tube from the liquid inlet;

[0012] Step 2: The gaseous reactant pushes the liquid reactant from the first tube into the reaction tube of the reactor, and reacts under the condition that the ultraviolet lamp emits ultraviolet light and irradiates the reaction tube to obtain a gas-liquid mixture containing the target product;

[0013] Step 3: The gas-liquid mixture flows through the gas-liquid confluence inlet and gas-liquid confluence outlet of the confluence device and finally passes into the gas-liquid separator for gas-liquid separation to obtain the target product.

[0014] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the step 2 is specifically: the gaseous reactant pushes the liquid reactant into the reactor to react under the conditions of a temperature of 65 to 70° C. and an ultraviolet lamp emitting ultraviolet light and irradiating the reaction tube to obtain a gas-liquid mixture containing the target product;

[0015] The gaseous reactant is chlorine or a mixture of chlorine and nitrogen;

[0016] The liquid reactant is ethylene carbonate in a molten state.

[0017] In the above-mentioned method for synthesizing chloroethylene carbonate in a continuous microchannel, the gaseous reactant is a mixture of chlorine and nitrogen, and the molar ratio of chlorine to nitrogen in the mixture is 3:1.

[0018] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the step 3 is specifically: the gas-liquid mixture flows through the gas-liquid confluence inlet and the gas-liquid confluence outlet of the confluence device and finally passes into the gas-liquid separator for gas-liquid separation, and the content of ethylene chlorocarbonate in the separated liquid substance is detected. When the mass fraction of ethylene chlorocarbonate in the liquid substance is less than 80%, step 1 is repeated;

[0019] When the mass fraction of ethylene chlorocarbonate in the liquid substance is greater than or equal to 80%, deacidifying the liquid substance to obtain the target product;

[0020] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the reaction tube is a straight tube, the inner diameter of the reaction tube is preferably 1 to 5 mm, and the wall thickness is preferably 0.1 to 2 mm.

[0021] In the above-mentioned method for synthesizing chloroethylene carbonate in a continuous microchannel, cavities are provided inside the shell and outside the reaction tube and the ultraviolet lamp tube;

[0022] The shell is provided with a heat exchange medium inlet and a heat exchange medium outlet, and the heat exchange medium inlet, the cavity, the heat exchange medium outlet, and the external heat exchanger are circulated and conducted.

[0023] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the power of the ultraviolet lamp is 20-250ww, and the wavelength of the ultraviolet light generated by the ultraviolet lamp is 245-370nm.

[0024] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the power of the ultraviolet lamp is 180W, and the wavelength of the ultraviolet light generated by the ultraviolet lamp is 365nm.

[0025] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the gas-liquid mixing module is provided with a pressure gauge, and the pressure gauge is used to detect the internal air pressure of the first tube.

[0026] In the above-mentioned method for synthesizing ethylene chlorocarbonate in a continuous microchannel, the reaction tube is a reaction tube made of glass, fiber or high molecular polymer with a light transmittance of not less than 50%.

[0027] The beneficial effects of this application are:

[0028] 1. The device for continuous microchannel synthesis of chloroethylene carbonate of the present application is simple, easy to maintain, low in cost, and has basically no scale-up effect. The device can be used as a basic module, and industrial-scale production can be achieved through simple modular scale-up.

[0029] 2. The present invention adopts microchannel technology to realize continuous operation of vinyl chloride carbonate synthesis, which can greatly shorten the reaction time, make the reaction more selective, and reduce the by-products, thereby further improving the production capacity of the device while ensuring stable product quality.

[0030] 3. The reaction is significantly exothermic. The use of microchannel technology, combined with efficient heat exchange, can effectively and accurately control the temperature, pressure and flow of the reaction, ensuring that the reaction parameters do not change significantly, further improving the selectivity of ethylene carbonate, enhancing process stability, and ensuring product quality.

[0031] 4. In this process, feeding and discharging are carried out simultaneously, and the residence time of the reactants is short. At the same time, nitrogen is used to reduce the chlorine partial pressure, control the formation of dichloro products, and ensure the purity of chloroethylene carbonate.

[0032] Each module adopts a multi-channel parallel connection mode, which solves the technical problems of small liquid holding capacity and low output per unit time of a single microchannel reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the device for continuous microchannel synthesis of ethylene chlorocarbonate in Example 1

[0034] Figure 2 Schematic diagram of the reactor in Example 1. DETAILED DESCRIPTION

[0035] The present application will be described clearly and completely below in conjunction with the examples of the present application. In the description of the present application, it should be noted that if the specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0036] Example 1

[0037] refer to Figure 1-2 , a device for continuous microchannel synthesis of chloroethylene carbonate, comprising a gas-liquid mixing module 1, a reactor 2, a flow confluence device 3, and a gas-liquid separator 4 which are connected in sequence;

[0038] The gas-liquid mixing module 1 comprises a first tube 5, a gas inlet 6 and a liquid inlet 7 are arranged on the side of the first tube 5, and the gas inlet 6 is arranged at the front end of the liquid inlet 7;

[0039] The reactor 2 includes a shell 8, a plurality of reaction tubes 9 disposed inside the shell 8, and a plurality of ultraviolet lamp tubes 10 disposed inside the shell 8;

[0040] The manifold 3 is provided with a gas-liquid confluence inlet and a gas-liquid confluence outlet, and the number of the gas-liquid confluence inlets corresponds to the number of the reaction tubes 9;

[0041] The first tube 5, the reaction tube 9, the gas-liquid confluence inlet, and the gas-liquid confluence outlet are connected in sequence;

[0042] The reaction tube 9 is a polyperfluoroethylene propylene tube. In this example, 80 reaction tubes are used, with an outer diameter of 2 mm, a wall thickness of 0.25 mm, and a length of 20 m.

[0043] In the actual practical process, the gaseous reactant can be introduced into the first tube 5 through the gas inlet 6, and the liquid reactant can be introduced into the first tube 5 through the liquid inlet 7;

[0044] Since the gas inlet 6 is disposed at the front end of the liquid inlet 7 and the first tube 5 is connected to the reaction tube 9, the operator can adjust the gas pressure to achieve gas pushing the liquid to move into the reaction tube 9 of the reactor 2;

[0045] When the gaseous reactants and the liquid reactants enter the reaction tube 9 together and react under the irradiation of the ultraviolet light emitted by the ultraviolet lamp tube 10 wound around the reaction tube 9, a gas-liquid mixture containing the target product is obtained;

[0046] Furthermore, as the gaseous reactants and liquid reactants are continuously introduced into the first tube 5, the reaction tube 9 and the manifold 3, the gas-liquid mixture containing the target product is pushed to the gas-liquid separator 4 for separation;

[0047] At the same time, it should be noted that, in order to meet the requirements of environmental protection, the present application sets up an external tail gas recovery and treatment device to recover the tail gas separated by the gas-liquid separator 4;

[0048] At the same time, the scheme can also set up a deacidification device to deacidify the target product that needs to be deacidified.

[0049] Preferably, a cavity 11 is provided inside the shell 8 and outside the reaction tube 9 and the ultraviolet lamp 10;

[0050] The shell 8 is provided with a heat exchange medium inlet 12 and a heat exchange medium outlet 13, and the heat exchange medium inlet 12, the cavity 11, the heat exchange medium outlet 13, and the external heat exchanger are circulated and conducted;

[0051] Of course, the present application takes into account that some reactions may be endothermic reactions. In order to more fully heat the gaseous reactants and liquid reactants in the reaction tube 9 evenly, the present solution provides a heat exchange medium inlet 12 and a heat exchange medium outlet 13. The operator can select the heat exchange medium according to actual needs. Specifically, in the present solution, in order to achieve efficient synthesis of ethylene chloride, the present application selects dry air as the heat exchange medium to increase the temperature in the cavity 11 to a preset temperature (65-70°C). It should be noted that in the subsequent embodiments, when applying the present device, the above-mentioned heat exchange medium and preset temperature are used.

[0052] Preferably, the power of the ultraviolet lamp tube 10 is 20-250W, and the wavelength of the ultraviolet light generated by the ultraviolet lamp tube 10 is 245-370nm.

[0053] Preferably, the power of the ultraviolet lamp tube 10 is 180W, and the wavelength of the ultraviolet light generated by the ultraviolet lamp tube 10 is 365nm.

[0054] Preferably, the gas-liquid mixing module 1 is provided with a pressure gauge 14 , and the pressure gauge 14 is used to detect the internal air pressure of the first tube 5 .

[0055] Preferably, the reaction tube 9 is a reaction tube 9 made of glass, fiber or high molecular polymer with a light transmittance of not less than 50%.

[0056] It should be noted that the subsequent embodiments all use the above-mentioned device to synthesize chloroethylene carbonate. Unless otherwise specified, the subsequent embodiments will not change the structure and part specifications of the above-mentioned embodiment.

[0057] Example 2

[0058] A method for continuously synthesizing ethylene chlorocarbonate in a microchannel comprises the following steps:

[0059] Step 1: Chlorine gas is introduced into the first tube from the gas inlet at a flow rate of 38000 ml / min, and molten ethylene carbonate is introduced into the first tube from the liquid inlet at a flow rate of 400 ml / min;

[0060] Step 2: Chlorine gas pushes molten ethylene carbonate into the reaction tube of the reactor and controls the temperature at 67±2°C through a heat exchange medium, turns on a 180W ultraviolet lamp and emits ultraviolet light with a wavelength of 365nm to irradiate the reaction tube to react, thereby obtaining a gas-liquid mixture containing the target product;

[0061] Step 3: passing the gas-liquid mixture through a flow combiner and finally into a gas-liquid separator for gas-liquid separation, detecting the content of ethylene chlorocarbonate in the separated liquid substance, and measuring that the mass fraction of ethylene chlorocarbonate is less than 80%, and repeating step 1;

[0062] Repeat steps 1-3 three times according to the above method, and use the liquid substance obtained after gas-liquid separation in step 3 as the liquid reactant in step 1 during the repetition process;

[0063] After repeating the process three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 85.97%. After calculation, the yield of ethylene carbonate was 83.07%.

[0064] Example 3

[0065] The method is substantially the same as Example 2, except that, in step 1, a mixed gas of chlorine and nitrogen is used to replace the chlorine, and the molar ratio of chlorine to nitrogen is 2:1;

[0066] After steps 1-3 were repeated three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 82.34%. After calculation, the yield of ethylene carbonate was 80.17%.

[0067] Example 4

[0068] The method is substantially the same as Example 2, except that, in step 1, a mixed gas of chlorine and nitrogen is used to replace the chlorine, and the molar ratio of chlorine to nitrogen is 4:1;

[0069] After steps 1-3 were repeated three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 84.08%. After calculation, the yield of ethylene carbonate was 81.21%.

[0070] Example 5

[0071] The method is basically the same as Example 2, except that the power of the ultraviolet lamp is 150w and the ultraviolet light with a wavelength of 365nm is emitted;

[0072] After steps 1-3 were repeated three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 82.12%. After calculation, the yield of ethylene carbonate was 80.24%.

[0073] Example 6

[0074] The method is basically the same as Example 2, except that the power of the ultraviolet lamp is 220w and the ultraviolet light with a wavelength of 365nm is emitted;

[0075] After steps 1-3 were repeated three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 83.02%. After calculation, the yield of ethylene carbonate was 81.73%.

[0076] Example 7

[0077] The method is basically the same as Example 2, except that the power of the ultraviolet lamp is 240W and the ultraviolet light emitted is 254nm in wavelength;

[0078] After steps 1-3 were repeated three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 84.58%. After calculation, the yield of ethylene carbonate was 81.27%.

[0079] Example 8

[0080] The method is basically the same as Example 2, except that the power of the ultraviolet lamp is 180W and the ultraviolet light with a wavelength of 254nm is emitted;

[0081] After steps 1-3 were repeated three times, the content of ethylene carbonate in the liquid substance obtained after gas-liquid separation in step 3 was detected, and the total conversion rate of ethylene carbonate was 84.59%. After calculation, the yield of ethylene carbonate was 82.40%.

Claims

1. A method for continuously synthesizing ethylene chlorocarbonate in a microchannel, characterized in that: The method relates to a device for synthesizing chloroethylene carbonate, which comprises a gas-liquid mixing module, a reactor, a flow confluence device, and a gas-liquid separator which are connected in sequence; the gas-liquid mixing module comprises a first tube, a side of which is provided with a gas inlet and a liquid inlet, and the gas inlet is arranged at the front end of the liquid inlet; the reactor comprises a shell, a plurality of reaction tubes arranged inside the shell, and a plurality of ultraviolet lamp tubes arranged inside the shell; the flow confluence device is provided with a gas-liquid confluence inlet and a gas-liquid confluence outlet, and the number of the gas-liquid confluence inlets corresponds to the number of the reaction tubes; the first tube, the reaction tube, the gas-liquid confluence inlet, and the gas-liquid confluence outlet are connected in sequence; The method comprises the following steps: Step 1: Pass the gaseous reactant into the first tube from the gas inlet, and pass the liquid reactant into the first tube from the liquid inlet; Step 2: The gaseous reactant pushes the liquid reactant from the first tube into the reaction tube of the reactor, and reacts under the condition that the ultraviolet lamp emits ultraviolet light and irradiates the reaction tube to obtain a gas-liquid mixture containing the target product; Step 3: The gas-liquid mixture flows through the gas-liquid confluence inlet and gas-liquid confluence outlet of the confluence device and finally passes into the gas-liquid separator for gas-liquid separation to obtain the target product.

2. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 1, characterized in that: The step 2 is specifically as follows: the gaseous reactant pushes the liquid reactant into the reactor to react at a temperature of 65-70° C. and the ultraviolet lamp emits ultraviolet light and irradiates the reaction tube to obtain a gas-liquid mixture containing the target product; The gaseous reactant is chlorine or a mixture of chlorine and nitrogen; The liquid reactant is ethylene carbonate in a molten state.

3. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 1, characterized in that: The gaseous reactant is a mixture of chlorine and nitrogen, and the molar ratio of chlorine to nitrogen in the mixture is 3:

1.

4. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 1, characterized in that: The step 3 specifically comprises: passing the gas-liquid mixture through the gas-liquid confluence inlet and the gas-liquid confluence outlet of the confluence device and finally passing the gas-liquid separator to separate the gas and liquid, detecting the content of chloroethylene carbonate in the separated liquid substance, and repeating step 1 when the mass fraction of chloroethylene carbonate in the liquid substance is less than 80%; When the mass fraction of ethylene chlorocarbonate in the liquid substance is greater than or equal to 80%, the liquid substance is deacidified to obtain the target product.

5. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 1, wherein: The reaction tube is a straight tube, and the inner diameter of the reaction tube is preferably 1-5 mm, and the wall thickness is preferably 0.1-2 mm.

6. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 5, wherein: A cavity is provided inside the shell and outside the reaction tube and the ultraviolet lamp tube; The shell is provided with a heat exchange medium inlet and a heat exchange medium outlet, and the heat exchange medium inlet, the cavity, the heat exchange medium outlet, and the external heat exchanger are circulated and conducted.

7. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 5, wherein: The power of the ultraviolet lamp is 20-250ww, and the wavelength of the ultraviolet light generated by the ultraviolet lamp is 245-370nm.

8. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 7, wherein: The power of the ultraviolet lamp is 180W, and the wavelength of the ultraviolet light generated by the ultraviolet lamp is 365nm.

9. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 5, characterized in that: The gas-liquid mixing module is provided with a pressure gauge, and the pressure gauge is used to detect the internal air pressure of the first tube.

10. The method for synthesizing ethylene chlorocarbonate by continuous microchannel according to claim 5, characterized in that: The reaction tube is a reaction tube made of glass, fiber or high molecular polymer with a light transmittance of not less than 50%.

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