Method for producing monochloroethylene carbonate with low ethylene carbonate content

Abstract

The invention provides a method for producing monochloroethylene carbonate with low ethylene carbonate content, and the monochloroethylene carbonate prepared by the method provided by the invention can improve the production efficiency and yield, and can significantly reduce the EC content in a CEC product at the same time. The method comprises the following steps: (1) in a main reactor, chlorine is introduced into a material at least containing an ethylene carbonate liquid to carry out a chlorination reaction in a boiling state, and the reaction pressure of the chlorination reaction is lower than normal pressure; and (2) feeding a gas-phase material flow obtained in the main reactor into a rectifying tower for separation, and obtaining a gas-phase product from the top of the rectifying tower.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of chloroethylene carbonate, and particularly relates to a method for producing chloroethylene carbonate with a low content of ethylene carbonate. Background Art

[0002] Chloroethylene carbonate (CEC) is a key intermediate for synthesizing important additives vinylene carbonate (VC) and fluoroethylene carbonate (FEC) in lithium-ion battery electrolytes. In addition, CEC can also be used as a solvent and an organic synthesis intermediate. Currently, the CEC products sold on the market are products with a CEC mass content of about 80%. The lack of high-purity industrial production limits its wider promotion.

[0003]

[0004] Currently, commercially available industrial CEC products are mainly obtained by chlorination reaction of ethylene carbonate (EC) with chlorinating reagents, which is common knowledge in the industry. For example, the literature reported by Newman and Addor in JACS, 1953, P1263 and JACS 1955, P3789 in 1953 shows that EC undergoes photochlorination reaction under the conditions of 60 - 70 °C and the presence of a solvent using ultraviolet light irradiation, and the obtained CEC is purified by high-vacuum rectification. Commonly used chlorinating agents include sulfuryl chloride, phosgene, chlorine, etc. Since the sulfuryl chloride method generates a large amount of acidic gases and causes serious pollution, it cannot meet the current environmental protection requirements and has been gradually phased out; phosgene is highly toxic and has poor atom economy and has not been widely promoted on a large scale industrially; the current industrial production process mainly uses the chlorine method. The chlorine method belongs to a free radical reaction in terms of reaction mechanism. According to different ways of initiating free radicals, it is divided into a chemical catalysis method and a photocatalysis method. The chemical catalysis method uses chemical initiators such as benzoyl peroxide (BPO) and other chemical reagents to initiate chlorine to generate chlorine free radicals, and the photocatalysis method uses ultraviolet or visible light to initiate the generation of chlorine free radicals. Because the photocatalysis method is environmentally friendly, efficient, and does not introduce other chemical impurities, it is currently the method commonly used in industrial plants at home and abroad.

[0005] For example, the process disclosed by CNOOC Tianjin Chemical Research and Design Institute in "Synthesis Research of Chloroethylene Carbonate" has reaction conditions in a kettle reactor: temperature 80 - 90 °C; reaction time 4 h, and the reaction yield is 82.5%. The process disclosed by Evonik Industries AG in US8022231B2 has reaction conditions: temperature 40 - 45 °C, reaction time = 7.8 h, reaction results: X = 79.24, Y = 76.6%, S = 96.67, and the content of the reaction liquid product w(CEC) = 80.7%.

[0006] In addition, because the boiling points of the reaction product CEC and the raw material EC are very close, the distillation separation is difficult, and both CEC and EC are heat-sensitive substances. In the traditional production process, the reaction products need to be separated under high temperature and long residence time distillation operation, which is prone to side reactions, further reducing the yield. Therefore, in actual industrial production time, manufacturers use the method of increasing the EC conversion rate as much as possible, and the photochlorination product is directly sent to the next process without separation to prepare VC and FEC. The typical composition of CEC products currently on the market includes: CEC 80-82%, EC 5-7%, DCEC 5-7% and other impurities. At present, a small amount of unreacted EC in the industrial production process of VC and FEC is directly mixed into high-boiling point tar as a by-product waste for incineration treatment, and is not recycled, which also causes a waste of raw materials and increases production costs. At the same time, as a key intermediate for the synthesis of VC and FEC, the remaining EC in CEC will reduce the reaction yield and become an impurity of VC and FEC products, affecting the quality of VC and FEC products. Therefore, a high-purity CEC product without EC or with a low EC content is also of great significance for improving the quality of VC and EFC products and reducing the difficulty of product separation and purification.

[0007] In summary, the existing commercially available industrial CEC products are mostly impure and have low purity, which limits their wider application. The existing known CEC synthesis processes have relatively low yields and high product costs. In addition, the existing CEC industrial devices in China generally adopt intermittent processes, with an operation time of up to 12-20 hours per batch, and low production efficiency.

[0008] How to provide a CEC production process that is beneficial to improving production efficiency, improving yield and reducing EC content is one of the technical problems to be solved urgently in this field. Summary of the invention

[0009] The invention provides a method for producing monochloroethylene carbonate with low ethylene carbonate content. The method of the invention is used to prepare monochloroethylene carbonate, which can improve production efficiency and yield and significantly reduce the EC content in the CEC product.

[0010] To achieve the purpose, the present invention provides the following technical solutions:

[0011] The present invention provides a method for producing monochloroethylene carbonate with low ethylene carbonate content, the method comprising the following steps:

[0012] (1) In a main reactor, chlorine gas is introduced into a material containing at least ethylene carbonate liquid to carry out a chlorination reaction under boiling conditions, wherein the reaction pressure of the chlorination reaction is lower than normal pressure;

[0013] (2) The gaseous feed stream obtained in the main reactor is fed into a distillation column for separation, and a gaseous product is obtained from the top of the distillation column.

[0014] In some embodiments, in the main reactor, the reaction temperature reaches at least the bubble point temperature of the ethylene carbonate liquid under the reaction pressure;

[0015] Preferably, the reaction pressure of the chlorination reaction is controlled to be lower than atmospheric pressure and the bubble point temperature of the ethylene carbonate liquid under this pressure is 40 - 100 °C;

[0016] Preferably, the reaction pressure of the chlorination reaction is 30 - 1000 PaA, preferably 100 - 500 PaA; preferably, the reaction temperature of the chlorination reaction is 40 - 100 °C, more preferably 50 - 80 °C;

[0017] In the main reactor, the liquid phase residence time is, for example, 1 - 8 h, for example, 2 - 5 h, for example, 4 - 8 h;

[0018] Preferably, the chlorination reaction is carried out under photocatalysis, and the light source for the photocatalysis is, for example, visible light or ultraviolet light, preferably ultraviolet light.

[0019] In some embodiments, before the step (1), a pre - reaction stage is further included, and the steps of the pre - reaction stage include:

[0020] Chlorine gas and the ethylene carbonate liquid are subjected to a partial chlorination reaction in a pre - reactor to obtain a pre - reaction feed liquid, and the pre - reaction feed liquid is fed into the main reactor as the material at least containing the ethylene carbonate liquid to carry out the chlorination reaction of the step (1);

[0021] The reaction in the pre - reactor is carried out at atmospheric pressure or above atmospheric pressure;

[0022] Preferably, the partial chlorination reaction is carried out under photocatalysis, and the light source for the photocatalysis is, for example, visible light or ultraviolet light, preferably ultraviolet light.

[0023] In some embodiments, the partial chlorination reaction is carried out in one pre - reactor or multiple pre - reactors connected in series;

[0024] Each of the pre - reactors is respectively connected to a gas - liquid separation tank, and the reaction feed liquid output from the pre - reactor is fed into the gas - liquid separation tank for gas - liquid separation, and a liquid phase part and a gas phase part are obtained;

[0025] When the partial chlorination reaction is carried out in one pre - reactor, the liquid phase part separated from the reaction feed liquid output from the pre - reactor by the gas - liquid separation tank is used as the pre - reaction feed liquid and fed into the main reactor;

[0026] When the partial chlorination reaction is carried out in a plurality of pre-reactors connected in series, the liquid phase separated from the reaction feed liquid output from the upper-stage pre-reactor by the gas-liquid separation tank is fed into the lower-stage pre-reactor for continuous reaction, and the liquid phase separated from the reaction feed liquid output from the last-stage pre-reactor by the gas-liquid separation tank is used as the pre-reaction feed liquid and fed into the main reactor; preferably, chlorine gas is introduced into each pre-reactor.

[0027] Preferably, the gas phase separated in the gas-liquid separation tank is fed into the tail gas absorption tower for treatment.

[0028] Preferably, the pre-reactor is a kettle-type, tower-type or tube-type reactor, preferably a tube-type reactor, and more preferably a microchannel reactor.

[0029] In some embodiments, when the partial chlorination reaction is carried out in a plurality of pre-reactors connected in series, the reaction pressure of the upper-stage pre-reactor is equal to or higher than that of the lower-stage pre-reactor; preferably, the reaction temperature of the upper-stage pre-reactor is higher than that of the lower-stage pre-reactor.

[0030] Preferably, the reaction pressure of each pre-reactor is higher than the pressure of the gas-liquid separation tank for separating the reaction feed liquid of the corresponding pre-reactor.

[0031] In some embodiments, the reaction in the pre-reactor is carried out under a pressurized condition, preferably 0.1-2 MpaA.

[0032] Preferably, the reaction temperature in the pre-reactor is 60-120 °C, preferably 60-100 °C, more preferably 60-90 °C; preferably, in the pre-reaction stage, the reaction temperature of the pre-reactor is not lower than the reaction temperature of the main reactor, and preferably the reaction temperature of at least one pre-reactor is higher than the reaction temperature of the main reactor.

[0033] Preferably, the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be <50%, preferably <40%, further preferably <30%, and more preferably <20%.

[0034] Preferably, the pre-reactor is a microchannel reactor, and preferably the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be <20%, and more preferably <15%.

[0035] In some embodiments, in the pre-reactor and the main reactor, the total liquid phase residence time is 0.5-8 h.

[0036] In some embodiments, in step (2), the operating conditions of the distillation column include:

[0037] The bottom pressure of the column is 30 - 1000 PaA, the bottom temperature of the column is 30 - 90 °C, and the reflux ratio is 1 - 10:1.

[0038] In some embodiments, the gaseous product obtained at the top of the distillation column in step (2) is condensed to obtain a crude product;

[0039] The crude product is crystallized to obtain a chloroethylene carbonate product;

[0040] Preferably, the crystallization is melt crystallization, and the preferred crystallization temperature is 10 - 30 °C;

[0041] Preferably, the residual gas phase obtained after condensing the gaseous product is sent to a tail gas absorption tower for treatment.

[0042] In some embodiments, the molar ratio of the total amount of ethylene carbonate used to the total amount of chlorine used is 1:1.05 - 1.5, preferably 1.05 - 1.1.

[0043] The technical solution provided by the present invention has the following beneficial effects:

[0044] 1) Chlorine gas is introduced into the EC raw material in a boiling state under sub - atmospheric pressure for reaction. The reaction system has a better heat removal capacity, which is conducive to avoiding side reactions caused by excessive local temperature in the system. At the same time, the reaction product CEC can evaporate into the gas phase as quickly as possible and is immediately followed by distillation operation, which can avoid multiple heating of the product CEC during multiple distillation processes, significantly reducing the residence time of the CEC product in the high - temperature region and further reducing side reactions.

[0045] 2) In the preferred solution, by setting a pre - reactor in front of the main reactor, it is conducive to improving the reaction efficiency and reducing costs.

[0046] 3) Using the method of the present invention can obtain a high - purity chloroethylene carbonate (CEC) product. The obtained product has a low EC content, and even a CEC product almost free of impurities such as EC can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the production process flow in one embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] To facilitate the understanding of the present invention, the present invention will be further described below in conjunction with embodiments. It should be understood that the following embodiments are only for better understanding of the present invention and do not mean that the present invention is limited only to the following embodiments.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The term "and / or" as used herein may include any and all combinations of one or more of the related listed items.

[0050] The present invention provides a method for producing ethylene chlorocarbonate with a low ethylene carbonate content, and the method comprises the following steps:

[0051] (1) In a main reactor, chlorine gas is introduced into a material containing at least ethylene carbonate liquid and subjected to a chlorination reaction under a boiling state, and the reaction pressure of the chlorination reaction is lower than normal pressure;

[0052] (2) The gas-phase feed stream obtained in the main reactor is sent to a distillation column for separation, and a gas-phase product is obtained from the top of the distillation column.

[0053] In the CEC preparation method provided by the present invention, under the condition of lower than normal pressure, chlorine gas is introduced into a liquid material containing at least ethylene carbonate liquid in a boiling state for a chlorination reaction, which can not only obtain a relatively fast reaction rate, but also greatly reduce side reactions and lower production costs. The obtained product can obtain a CEC product with a lower EC content without undergoing multiple distillation separations. The reaction process of the present invention conducts the chlorination reaction above the bubble point temperature of ethylene carbonate under lower than normal pressure, and the heat transfer capacity of the reaction system is significantly improved. The residence time of the product in the system is short, the reaction rate is fast, and the side reactions are few.

[0054] In the method of the present invention, chlorine gas is introduced into a liquid material containing EC liquid in a boiling state for a reaction. The heat generated in the highly exothermic chlorination reaction directly acts on the bubble point EC system, causing a large amount of gasification of EC and the reaction product in the bubble point system, removing the reaction heat from the reaction liquid phase system, and achieving better temperature control. At the same time, because the boiling point of CEC is lower than that of EC, CEC is more likely to exist in the gas-phase product. After the separation of the distillation column, a purified CEC product can be obtained at the top of the column. This process does not require multiple distillation operations as in the traditional process, and can avoid the secondary heating and longer residence time of CEC caused by subsequent distillation operations, thereby further avoiding side reactions and increasing the yield.

[0055] Further, in the main reactor, the reaction temperature reaches at least the bubble point temperature of the ethylene carbonate liquid under the reaction pressure; preferably, in some preferred embodiments, in the main reactor, the reaction pressure of the chlorination reaction is controlled to be lower than atmospheric pressure and the bubble point temperature of the ethylene carbonate liquid under this pressure is 40-100 °C, such as 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, etc., for example 60-100 °C; in some preferred embodiments, the reaction pressure of the chlorination reaction is 30-1000 PaA, such as 30 PaA, 60 PaA, 100 PaA, 200 PaA, 300 PaA, 400 PaA, 500 PaA, 700 PaA, 1000 PaA, etc., preferably 100-500 PaA; preferably, the reaction temperature of the chlorination reaction is 40-100 °C, such as 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, etc., more preferably 50-80 °C, and preferably the reaction temperature is maintained constant during the reaction; reacting under the above pressure conditions, especially the preferred pressure conditions, the product CEC is significantly vaporized along with EC and thus enters the gas phase in large quantities to leave the liquid-phase reaction system, which is beneficial to significantly improving the reaction selectivity and further significantly increasing the yield. Generally speaking, it is significantly beneficial for cost reduction and is economical.

[0056] In some embodiments, in the solution without adding a pre-reaction stage, in the main reactor, the liquid-phase residence time is, for example, 1-8 h, such as 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc., for example 2-5 h, for example 4-8 h.

[0057] In some embodiments, the chlorination reaction is carried out under photocatalysis, and the light source for the photocatalysis is, for example, visible light or ultraviolet light, preferably ultraviolet light.

[0058] In a preferred embodiment, a pre-reaction stage is further included before the step (1), and the steps of the pre-reaction stage include:

[0059] Carry out a partial chlorination reaction on chlorine gas and ethylene carbonate liquid in a pre-reactor to obtain a pre-reaction feed liquid, and introduce the pre-reaction feed liquid as the material containing at least ethylene carbonate liquid into the main reactor to carry out the chlorination reaction of the step (1); the reaction in the pre-reactor is carried out at atmospheric pressure or above atmospheric pressure.

[0060] For consecutive reactions such as EC / CEC and thermosensitive systems, in order to further reduce side reactions and increase the product yield, the present inventors further improve the reaction efficiency and reduce the liquid-phase residence time by means of process intensification. After comparing various approaches, the present inventors propose a preferred solution of adding a pre-reaction process before the main reactor. The reactor form of the pre-reaction process can be a kettle reactor, a tower reactor, or a tubular reactor, preferably a tubular reactor; more preferably, a microchannel reactor is used. The pre-reactor is arranged before the main reactor, corresponding to the initial stage of the chlorination reaction. In this stage, for this consecutive chlorination reaction, the dichlorination and polychlorination reactions are based on the monochlorination product. The initial stage of the reaction is mainly the monochlorination reaction stage. By adding a pre-reaction stage, it is beneficial to further increase the reaction rate, further reduce the residence time, and at the same time more significantly avoid the possibility of significant side reactions occurring.

[0061] Preferably, the partial chlorination reaction is carried out under photocatalysis, and the light source for the photocatalysis is, for example, visible light or ultraviolet light, preferably ultraviolet light.

[0062] Furthermore, the partial chlorination reaction is carried out in one pre-reactor or multiple pre-reactors connected in series;

[0063] Each of the pre-reactors is respectively connected to a gas-liquid separation tank. The reaction feed liquid output from the pre-reactor is sent into the gas-liquid separation tank for gas-liquid separation, and a liquid phase part and a gas phase part are obtained;

[0064] When the partial chlorination reaction is carried out in one pre-reactor, the liquid phase part separated from the reaction feed liquid output from the pre-reactor by the gas-liquid separation tank is used as the pre-reaction feed liquid and sent into the main reactor;

[0065] When the partial chlorination reaction is carried out in multiple pre-reactors connected in series, the liquid phase part separated from the reaction feed liquid output from the upper-stage pre-reactor by the gas-liquid separation tank is sent into the next-stage pre-reactor for continuous reaction, and the liquid phase part separated from the reaction feed liquid output from the last-stage pre-reactor by the gas-liquid separation tank is used as the pre-reaction feed liquid and sent into the main reactor; preferably, chlorine gas is introduced into each pre-reactor. Preferably, the gas phase part separated in the gas-liquid separation tank is sent into a tail gas absorption tower for treatment. The number of pre-reactors is, for example, 1, 2, 3 or more.

[0066] In some preferred embodiments, when the partial chlorination reaction is carried out in a plurality of pre-reactors connected in series, the reaction pressure of the upper-stage pre-reactor is equal to or higher than that of the lower-stage pre-reactor; preferably, the reaction pressure of each pre-reactor is higher than the pressure of the gas-liquid separation tank for separating the reaction feed liquid of the corresponding pre-reactor. By carrying out the pre-reaction stage according to the above pressure relationship between the pre-reactions at each stage and between the pre-reactor and the gas-liquid separation tank, it is beneficial to further improve the reaction effect. The increased pressure is beneficial to increasing the solubility of chlorine gas in the liquid phase and increasing the reaction rate, but at the same time the decreased pressure is beneficial to the faster removal of the reaction product HCl and reducing the acidity of the liquid phase system to reduce side reactions; preferably, the pressure of the gas-liquid separation tank of the multi-stage pre-reactor decreases step by step to balance the requirements of reaction and degassing. Preferably, the reaction temperature of the upper-stage pre-reactor is higher than that of the lower-stage pre-reactor, which is beneficial to further improving the reaction effect.

[0067] In some preferred embodiments, the reaction in the pre-reactor is carried out under pressurized conditions, preferably 0.1-2 MpaA; preferably, the reaction temperature in the pre-reactor is 60-120 °C, preferably 60-100 °C, more preferably 60-90 °C; further preferably, in the pre-reaction stage, the reaction temperature of the pre-reactor is not lower than the reaction temperature of the main reactor, and preferably the reaction temperature of at least one pre-reactor is higher than the reaction temperature of the main reactor. Carrying out the reaction in the pre-reaction stage under the above preferred pressure and temperature conditions is beneficial to further improving the reaction efficiency and further reducing the residence time.

[0068] Preferably, the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be <50%, such as 45%, 40%, 39%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, etc., for example <50% is preferably <40%, further preferably <30%, and more preferably <20%;

[0069] Preferably, the pre-reactor is a microchannel reactor, and preferably the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be <20%, more preferably <15%.

[0070] In some embodiments, the pre-reactor is preferably operated under pressurized conditions, such as 0.1 - 2 MPaA, for example 0.1 MPaA, 0.5 MPaA, 1 MPaA, 1.5 MPaA, 2 MPaA, etc.; the reaction temperature is preferably 60 - 120 °C, for example 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, etc., for example 60 - 100 °C; meanwhile, the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be < 50%, preferably < 40%, preferably < 30%, more preferably < 20%. Under the above preferred reaction conditions, the product selectivity can be further significantly improved. For example, the mass ratio of CEC and DCEC in the pre-reaction product can be higher than 99:1. In a further preferred embodiment, when a microchannel reactor is used as the pre-reactor, under the above preferred reaction conditions, the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be < 20%, more preferably < 15%, which is beneficial to further significantly improve the product selectivity. For example, under the preferred conditions, the mass ratio of CEC and DCEC in the pre-reaction product can be higher than 99.5:0.5. For example, under more preferred conditions, the ratio of CEC and DCEC in the pre-reaction product can be higher than 99.8:0.2.

[0071] In some embodiments, the liquid-phase residence time of the pre-reactor is 1 - 60 s, for example 1 s, 3 s, 5 s, 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, etc.

[0072] In some embodiments, in the pre-reactor and the main reactor, the total liquid-phase residence time is 0.5 - 8 h, for example 0.5 h, 1 h, 3 h, 5 h, 8 h, etc.

[0073] In some embodiments, in step (2), the operating conditions of the distillation column include: the bottom pressure is 30 - 1000 PaA, the bottom temperature is 30 - 90 °C, and the reflux ratio is 1 - 10:1.

[0074] In some preferred embodiments, in the pre-reaction stage, the reaction temperature in the pre-reactor is 60 - 100 °C, the reaction pressure is 0.1 - 2 MpaA, and the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be < 30%; and, in step (1), the reaction temperature of the chlorination reaction in the main reactor is controlled to be 50 - 80 °C, the reaction pressure of the chlorination reaction is 30 - 1000 PaA, preferably 100 - 500 PaA, and the liquid-phase residence time is 0.7 - 8 h; under these reaction conditions, not only can good reaction efficiency be obtained, but also a relatively high product yield can be achieved, and the impurity content can be further reduced. In a further preferred embodiment, in the pre-reaction stage, the reaction temperature in the pre-reactor is 60 - 90 °C, and the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be < 20%; and, in step (1), the reaction temperature of the chlorination reaction in the main reactor is 50 - 80 °C, and the liquid-phase residence time is 0.9 - 8 h, which can further improve the product yield and reduce the impurity content.

[0075] In some preferred embodiments, the pre-reaction stage is not carried out. In step (1), the reaction temperature of the chlorination reaction in the main reactor is controlled to be 50 - 80 °C, the reaction pressure of the chlorination reaction is 30 - 1000 PaA, preferably 100 - 500 PaA, and the liquid-phase residence time is 4 - 8 h; under these reaction conditions, the product yield in the scheme without the pre-reaction stage can be further improved, and the impurity content can be further reduced.

[0076] In some embodiments, the gaseous product obtained at the top of the distillation column in step (2) is condensed to obtain a crude product. The crude product prepared by the method of the present invention has a low EC content, and its CEC content can reach a level of > 90%, or even > 95%. The crude product is crystallized to obtain a chloroethyl carbonate product; preferably, the crystallization is melt crystallization, and the preferred crystallization temperature is 10 - 30 °C; preferably, the residual gas obtained after condensing the gaseous product is sent to a tail gas absorption tower for treatment. By the method of the present invention for preparing CEC products, after distillation, condensation and crystallization, a CEC product almost free of EC can be obtained. For example, the EC content in the obtained product is < 1%, such as < 0.1%, or even < 0.05%.

[0077] In some embodiments, the molar ratio of the total amount of ethylene carbonate used to the total amount of chlorine used is 1:1.05 - 1.5, such as 1:1.05, 1:1.07, 1:1.10, 1:1.20, 1:1.30, 1:1.40, 1:1.50, etc., preferably 1.05 - 1.1.

[0078] The pressures mentioned in the text are all absolute pressures.

[0079] Unless otherwise specified in the text, the % are all wt%.

[0080] The "upper-stage pre-reactor", "lower-stage pre-reactor" and "last-stage pre-reactor" mentioned in the text are relative to the flow direction of the reaction feed liquid. For example, the reactor located upstream is called the upper-stage pre-reactor, and the reactor located downstream is called the lower-stage pre-reactor.

[0081] The uses of the CEC prepared by the present invention include but are not limited to being used for preparing high-purity VC and FEC, and then being used as additives for high-performance lithium battery electrolytes; and it can be used for various purposes such as solvents and organic synthesis intermediates.

[0082] The method of the present invention has at least the following characteristics and advantages:

[0083] 1) Chlorine gas is introduced into the EC raw material in a boiling state under sub-atmospheric pressure. The reaction heat is mainly used for the gasification process of EC and the reaction product CEC, significantly strengthening the heat removal capacity of the system, facilitating more precise control of the system temperature, and facilitating the avoidance of side reactions caused by excessive local temperature in the system.

[0084] 2) The process of the present invention facilitates the evaporation of the reaction product CEC into the gas phase as quickly as possible, and immediately followed by distillation operation, which can avoid the secondary heating of the product CEC in the secondary distillation process, significantly reducing the residence time of the CEC product in the high-temperature region and further reducing side reactions.

[0085] 3) In the preferred embodiment, by setting one or more pre-reactors in front of the main reactor and carrying out pre-reaction under increased pressure, it is beneficial to improve the reaction efficiency and reduce costs; in a further preferred embodiment, in combination with the preferred pressure and temperature conditions, while ensuring the high selectivity of the reaction, the reaction rate is further increased, the liquid phase residence time is reduced, which is beneficial to further reduce side reactions and further reduce production costs.

[0086] 4) Using the method of the present invention can prepare high-purity chloroethylene carbonate (CEC) products. The obtained products have a low EC content, and even CEC products almost free of impurities such as EC can be obtained. For example, the EC content in the obtained products is <1%, such as <0.1%, and even <0.05%.

[0087] In summary, compared with the currently mainstream industrial known technologies, the process and device disclosed in the present invention can significantly reduce side reactions and production costs, and have outstanding economic advantages.

[0088] The following further exemplarily illustrates the solution of the present invention in combination with embodiments. However, the present invention is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights required by the present invention.

[0089] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0090] Raw material information: The ethylene carbonate and Cl2 raw materials used in the examples of the present invention are produced by the Yantai Industrial Park facility of Wanhua Chemical Company.

[0091] Pressure-resistant photocatalytic reactor: Peshel reactor;

[0092] Microchannel photocatalyst reactor: Corning G1 microchannel reactor.

[0093] In the following embodiments, some embodiments adopt Figure 1 The process flow and device shown. The process system includes a pre-reactor 1, a pre-reactor 2, a gas-liquid separation tank 3 and a gas-liquid separation tank 4 used in the pre-reaction stage, a main reactor and a distillation tower in the main reaction stage, and a tail gas absorption tower. The distillation tower is equipped with a buffer tank and a condenser. In the pre-reactor 1, EC and chlorine undergo a partial chlorination reaction, and the obtained reaction liquid enters the gas-liquid separation tank 3 for gas-liquid separation, the gas phase enters the tail gas absorption tower for treatment, and the liquid phase enters the pre-reactor 2 to continue to undergo a partial chlorination reaction with the introduced chlorine; the reaction liquid obtained in the pre-reactor 2 enters the gas-liquid separation tank 4 for gas-liquid separation, the gas phase enters the tail gas absorption tower for treatment, and the liquid phase (i.e., the material containing at least ethylene carbonate liquid) enters the main reactor to continue to undergo a chlorination reaction with the introduced chlorine; the gas phase stream obtained in the main reactor enters the distillation tower for separation, and a gas phase product is obtained from the top of the distillation tower. The gas phase product enters the condenser for condensation, and then enters the buffer tank. The liquid product obtained by condensation is partially refluxed and partially extracted as a crude product; the residual gas phase outlet of the buffer tank and the gas phase inlet of the tail gas absorption tower are connected through a pipeline, and a vacuum pump is provided on the pipeline. The main reactor and the pre-reactors 1 and 2 are both equipped with ultraviolet light sources, and the tail gas is treated in the tail gas absorption tower with an aqueous NaOH solution as an absorbent.

[0094] Example 1

[0095] References Figure 1 The process flow and device described above are different in that there is no pre-reactor 1, pre-reactor 2, gas-liquid separation tank 3 and gas-liquid separation tank 4. The main reactor is a pressure-resistant photocatalytic reactor of Peshel Company, with a volume of 1L, equipped with a UV light source with a power of 500w and a UV wavelength of 365nm. The distillation tower has a diameter of 30mm and is filled with a 3*3mm glass spring filler with a height of 1m on the top.

[0096] Operating conditions: Heat the EC liquid in the main reactor to 60°C, adjust the pressure in the main reactor through a vacuum pump, and make the liquid in the main reactor start to boil under a pressure lower than atmospheric pressure. Start introducing chlorine gas, with a molar ratio of EC to chlorine gas of 1:1.2. Calculate the liquid residence time as 4 h based on the volume of the liquid phase in the reaction kettle / the volume flow rate of EC feed. Turn on the ultraviolet light source and gradually increase the light source power to 500 W. At the same time, adjust the system pressure to maintain the temperature in the kettle stable at 60°C, and keep the liquid in the main reactor in a boiling state. After the system stabilizes, the top pressure of the distillation column is 30 PaA, the top temperature is 40°C, the bottom pressure (i.e., the pressure in the main reactor) is 100 PaA, the bottom temperature is 60°C, and the reflux ratio of the distillation column is 6:1. Continuously feed the material, and continue to operate for 6 hours after the system stabilizes, then take samples for GC analysis. The gaseous product at the top of the distillation column is condensed to obtain the CEC crude product, and the final product is obtained through two-stage melt crystallization. The crystallization conditions include: starting temperature 30°C, cooling rate 1°C / h to the termination temperature 10°C, and take samples of the crystallized product for GC analysis.

[0097] Reaction results: The GC purity of the CEC crude product taken from the top of the distillation column is 98.2%, the DCEC content is 0.5%, the EC content is 1.2%, and the total reaction yield is 96.5%. The purity of the final product CEC obtained by crystallization is 99.95%, and the EC content is <0.05%.

[0098] Example 2

[0099] Refer to the Figure 1 process flow and device as described above, with the difference that: there is no pre-reactor I, pre-reactor 2, gas-liquid separation tank 3, and gas-liquid separation tank 4. The main reactor is a pressure-resistant photocatalytic reaction kettle from Peshel Company with a volume of 1 L, equipped with an ultraviolet light source with a power of 500 W and an ultraviolet light wavelength of 365 nm. The diameter of the distillation column is 30 mm, and the upper part is filled with 3*3 mm glass spring packing with a height of 1 m.

[0100] Operating conditions: Heat the EC liquid in the main reactor to 50 °C, adjust the pressure in the main reactor with a vacuum pump, and under a pressure lower than atmospheric pressure, make the liquid in the main reactor start to boil. Start introducing chlorine gas, with a molar ratio of EC to chlorine of 1:1.1. Calculate the liquid-phase residence time as 8 h based on the volume of the liquid phase in the reaction kettle and the EC feed volume flow rate. Turn on the ultraviolet light source and gradually increase the light source power to 500 W. At the same time, adjust the system pressure to maintain the temperature in the kettle stable at 50 °C, and keep the liquid in the main reactor in a boiling state. After the system stabilizes, the top pressure of the distillation column is 30 PaA, the top temperature is 40 °C, the bottom pressure (i.e., the pressure in the main reactor) is 100 PaA, the bottom temperature is 50 °C, and the reflux ratio of the distillation column is 6:1. Continuously feed the material. After the system stabilizes, continue to operate for 6 hours, and take samples for GC analysis. The gaseous product at the top of the distillation column is condensed to obtain the CEC crude product, and the final product is obtained through two-stage melt crystallization. The crystallization conditions include: starting temperature 30 °C, cooling rate 1 °C / h to the termination temperature 10 °C, and take samples of the crystallized product for GC analysis.

[0101] Reaction results: The GC purity of the CEC crude product taken from the top of the distillation column is 98.0%, the DCEC content is 0.6%, the EC content is 1.3%, and the total reaction yield is 95.0%. The purity of the final product CEC obtained by crystallization is 99.95%, and the EC content is <0.05%.

[0102] Example 3

[0103] Adopt the Figure 1 process flow and device as described. The equipment is the same as that in Example 1. Refer to the description in Example 1 and will not be elaborated here.

[0104] Operating conditions:

[0105] Other conditions are the same as those in Example 1. Only the differences from Example 1 will be described below:

[0106] Heat the EC liquid in the main reactor to 100 °C, adjust the pressure in the main reactor with a vacuum pump, and under a pressure lower than atmospheric pressure, make the liquid in the main reactor start to boil. Introduce chlorine gas, and the liquid-phase residence time is 2 h. After the system stabilizes (temperature is 100 °C), the top pressure of the distillation column is 30 PaA, the top temperature is 40 °C, the bottom pressure (i.e., the pressure in the main reactor) is 500 PaA, the bottom temperature is 100 °C, and the reflux ratio of the distillation column is 3:1. Continuously feed the material. After the system stabilizes, continue to operate for 6 hours, and take samples for GC analysis. The gaseous product at the top of the distillation column is condensed to obtain the CEC crude product, and the final product is obtained through two-stage melt crystallization. The crystallization conditions include: starting temperature 30 °C, cooling rate 1 °C / h to the termination temperature 10 °C, and take samples of the crystallized product for GC analysis.

[0107] Reaction results: The GC purity of the crude CEC product taken from the top of the distillation column is 96.3%, the DCEC content is 1.2%, the EC content is 2.4%, and the total reaction yield is 94.5%. The purity of the final CEC product obtained by crystallization is 99.95%, and the EC content is <0.05%.

[0108] Example 4

[0109] Adopt the process flow and device as attached Figure 1 described, and other equipment is the same as that in Example 1, except that pre-reactors 1 and 2 and gas-liquid separation tanks 3 and 4 are added. The pre-reactor uses the Corning G1 microchannel reactor.

[0110] Operating conditions:

[0111] Pre-reaction stage: EC liquid and Cl2 are introduced into pre-reactor 1 for pre-reaction. The temperature of pre-reactor 1 is 120 °C, the pressure is 2 MPaA, the liquid-phase residence time is 2 s, the molar ratio of EC to Cl2 is 1:0.2, the power of the ultraviolet light source is 100 W, and the ultraviolet light wavelength is 365 nm; the pressure of gas-liquid separation tank 1 is 1.5 MPaA. Cl2 is introduced into pre-reactor 2 to continue the reaction with the liquid-phase part obtained from gas-liquid separation tank 3. The temperature of pre-reactor 2 is 100 °C, the pressure is 1 MPaA, the liquid-phase residence time is 2 s, the molar ratio of EC introduced into pre-reactor 1 to Cl2 introduced into pre-reactor 2 is 1:0.2, the power of the ultraviolet light source is 100 W, and the ultraviolet light wavelength is 365 nm; the pressure of gas-liquid separation tank 4 is 0.5 MPaA. The liquid-phase part obtained from gas-liquid separation tank 4 enters the main reactor in the main reaction stage to continue the chlorination reaction with the introduced Cl2. The total conversion rate of ethylene carbonate in the pre-reaction stage is 39.2%.

[0112] Main reaction stage: Other conditions in the main reactor are the same as those in Example 1, except that: the power of the ultraviolet light source in the main reactor is 300 w, the liquid-phase residence time is 0.5 h, and the molar ratio of EC introduced into pre-reactor 1 to Cl2 introduced into the main reactor is 1:0.8; after the system is stable, continue to operate for 6 hours. The gaseous product at the top of the distillation column is condensed to obtain the crude CEC product, and two-stage melt crystallization is carried out with reference to Example 1 to obtain the final product, and the crystalline product is sampled for GC analysis.

[0113] Reaction results: The GC purity of the crude CEC product taken from the top of the distillation column is 96.0%, the DCEC content is 2.0%, the EC content is 1.9%, and the total reaction yield is 90.2%. The purity of the final CEC product obtained by crystallization is 99.95%, and the EC content is <0.05%.

[0114] From the comparison between Example 1 and Example 4, by adding the pre-reaction stage, the total liquid-phase residence time can be significantly shortened.

[0115] Example 5

[0116] Adopt the process flow and device as attached Figure 1 described, and the equipment is the same as that in Example 4.

[0117] Operating conditions:

[0118] Pre-reaction stage: In the pre-reactor 1, EC liquid and Cl2 are introduced for pre-reaction. The temperature of the pre-reactor 1 is 100 °C, the pressure is 2 MPaA, the liquid-phase residence time is 2 s, the molar ratio of EC to Cl2 is 1:0.15, the power of the ultraviolet light source is 75 W, and the ultraviolet light wavelength is 365 nm; the pressure of the gas-liquid separation tank 1 is 1.5 MPaA. Cl2 is introduced into the pre-reactor 2 and continues to react with the liquid-phase part obtained from the gas-liquid separation tank 3. The temperature of the pre-reactor 2 is 90 °C, the pressure is 1 MPaA, the liquid-phase residence time is 2 s, the molar ratio of EC introduced into the pre-reactor 1 to Cl2 introduced into the pre-reactor 2 is 1:0.25, the power of the ultraviolet light source is 75 W, and the ultraviolet light wavelength is 365 nm; the pressure of the gas-liquid separation tank 4 is 0.5 MPaA. The liquid-phase part obtained from the gas-liquid separation tank 4 enters the main reactor in the main reaction stage and continues to carry out chlorination reaction with the introduced Cl2. The total conversion rate of ethylene carbonate in the pre-reaction stage is 29%.

[0119] Main reaction stage: Other conditions in the main reactor are the same as those in Example 1, except that: the power of the ultraviolet light source in the main reactor is 350 w, the liquid-phase residence time is 0.8 h, and the molar ratio of EC introduced into the pre-reactor 1 to Cl2 introduced into the main reactor is 1:0.75; after the system is stable, continue to operate for 6 hours. The gas-phase product at the top of the distillation column is condensed to obtain the CEC crude product, and two-stage melt crystallization is carried out with reference to Example 1 to obtain the final product. The crystalline product is sampled and sent for GC analysis.

[0120] Reaction results: The GC purity of the CEC crude product taken from the top of the distillation column is 97.1%, the DCEC content is 1.0%, the EC content is 1.8%, and the total reaction yield is 96.1%. The purity of the final product CEC obtained by crystallization is 99.95%, and the EC content is <0.05%.

[0121] Example 6

[0122] Adopt the process flow and device as attached Figure 1 described, and the equipment is the same as that in Example 4.

[0123] Operating conditions:

[0124] Pre - reaction stage: In the pre - reactor 1, EC liquid and Cl2 are introduced for pre - reaction. The temperature of the pre - reactor 1 is 90 °C, the pressure is 2 MPaA, the liquid - phase residence time is 2 s, the molar ratio of EC to Cl2 is 1:0.1, the power of the ultraviolet light source is 50 W, and the ultraviolet light wavelength is 365 nm; the pressure of the gas - liquid separation tank 1 is 1.5 MPaA. In the pre - reactor 2, Cl2 is introduced to continue the reaction with the liquid - phase part obtained from the gas - liquid separation tank 3. The temperature of the pre - reactor 2 is 60 °C, the pressure is 1 MPaA, the liquid - phase residence time is 2 s, the molar ratio of EC introduced into the pre - reactor 1 to Cl2 introduced into the pre - reactor 2 is 1:0.15, the power of the ultraviolet light source is 50 W, and the ultraviolet light wavelength is 365 nm; the pressure of the gas - liquid separation tank 4 is 0.5 MPaA. The liquid - phase part obtained from the gas - liquid separation tank 4 enters the main reactor in the main - reaction stage to continue the chlorination reaction with the introduced Cl2. The total conversion rate of ethylene carbonate in the pre - reaction stage is 19.1%.

[0125] Main - reaction stage: Other conditions in the main reactor are the same as those in Example 1, except that: the power of the ultraviolet light source in the main reactor is 400 W, the liquid - phase residence time is 1.0 h, and the molar ratio of EC introduced into the pre - reactor 1 to Cl2 introduced into the main reactor is 1:0.9. After the system is stable, it continues to run for 6 hours. The gas - phase product at the top of the distillation column is condensed to obtain the CEC crude product, and two - stage melt crystallization is carried out with reference to Example 1 to obtain the final product. The crystalline product is sampled and sent for GC analysis.

[0126] Reaction results: The GC purity of the CEC product taken from the top of the distillation column is 98.0%, the DCEC content is 0.6%, the EC content is 1.4%, and the total reaction yield is 96.6%. The purity of the final product CEC obtained by crystallization is 99.95%, and the EC content is <0.05%.

[0127] From the results of Examples 4 - 6, it can be seen that after adding the pre - reactor, the reaction efficiency is improved, the total reaction residence time is significantly reduced, and the yield of the product CEC can still be maintained at a relatively high level; under optimized conditions, the by - product DCEC is further reduced, and the reaction yield of CEC is further improved.

[0128] Comparative Example 1

[0129] The inventor also carried out experiments on the photo - chlorination process with a micro - channel reactor as the main reactor and found that it is difficult to obtain a CEC product with high yield and high conversion rate by using a micro - channel reactor as the main reactor. The specific experimental process is as follows:

[0130] The Corning G1 microchannel reactor was adopted, and the power of the ultraviolet light source was 500 W. The light source was ultraviolet light with a wavelength of 365 nm. The raw material EC was transported to the G1 reactor by a pump, and Cl2 was sent to the G1 reactor through a pressurized steel cylinder with the flow rate controlled by a mass flowmeter. The two materials were mixed and reacted in the G1 microchannel reactor. The experimental conditions and results are as follows:

[0131]

[0132]

[0133] From the results of a series of experiments with the microchannel reactor as the main reactor, it can be seen that it is difficult for the microchannel reactor to balance good conversion rate and selectivity. The conversion rate and yield are relatively low, and the residence time of the microchannel reactor generally can only reach the second level. In the above series of experiments, even by means of increasing the reaction temperature to improve the conversion rate, the corresponding selectivity decreases significantly, and it is impossible to meet the requirement of balancing the conversion rate and yield needed for industrial production.

[0134] In the embodiment of the present invention, through the ingenious combination of the microchannel reactor and the main reactor, it is possible to balance the improvement of production efficiency and the increase of product yield, and the effect is remarkable.

[0135] Comparative Example 2

[0136] The photochlorination process with a kettle reactor as the reactor:

[0137] The same photocatalytic reaction kettle as in Example 1 was adopted. The power of the ultraviolet light source was 500 W, and the wavelength of the ultraviolet light was 365 nm. 300 g of EC was added to the reaction kettle, the temperature of the reaction kettle was controlled at 60 °C, chlorine gas was introduced, and the flow rate of chlorine gas was 4.5 L / h. Chlorine gas was continuously introduced for reaction for 12 h, and after the reaction ended, the temperature was cooled to room temperature. Then, excessive N2 gas was used to strip off HCl and unreacted chlorine gas to obtain 405 g of chlorinated liquid. The mass composition of the chlorinated liquid analyzed by GC is as follows: CEC 82%; DCEC 7.5%; EC 4.4%, and the total reaction yield is 75.4%.

[0138] From the above examples and comparative examples, it can be seen that the examples adopting the solution of the present invention can significantly shorten the reaction time required, and at the same time can significantly improve the purity of CEC in the product and reduce the content of impurities such as EC compared with the comparative examples adopting the traditional batch process.

[0139] It is easy to understand that the above examples are only for clear illustration and do not mean that the present invention is limited thereto. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for producing ethylene chlorocarbonate with a low content of ethylene carbonate, characterized in that, The method includes the following steps: (1) In the main reactor, chlorine gas is introduced into a material containing at least ethylene carbonate liquid, and a chlorination reaction is carried out under boiling conditions. The reaction pressure of the chlorination reaction is lower than atmospheric pressure; (2) The gas-phase feed stream obtained in the main reactor is sent to a distillation column for separation, and a gas-phase product is obtained from the top of the distillation column.

2. The method according to claim 1, wherein In the main reactor, the reaction temperature reaches at least the bubble point temperature of the ethylene carbonate liquid at the reaction pressure; Preferably, the reaction pressure of the chlorination reaction is controlled to be lower than atmospheric pressure, and the bubble point temperature of the ethylene carbonate liquid at this pressure is 40 - 100 °C; Preferably, the reaction pressure of the chlorination reaction is 30 - 1000 PaA, preferably 100 - 500 PaA; preferably, the reaction temperature of the chlorination reaction is 40 - 100 °C, more preferably 50 - 80 °C; In the main reactor, the liquid-phase residence time is, for example, 1 - 8 h, for example, 2 - 5 h, for example, 4 - 8 h; Preferably, the chlorination reaction is carried out under photocatalysis. The light source for the photocatalysis is, for example, visible light or ultraviolet light, preferably ultraviolet light.

3. The method according to claim 1 or 2, characterized in that, Before the step (1), a pre-reaction stage is further included. The steps of the pre-reaction stage include: Carrying out a partial chlorination reaction on chlorine gas and ethylene carbonate liquid in a pre-reactor to obtain a pre-reaction feed liquid, and introducing the pre-reaction feed liquid as the material containing at least ethylene carbonate liquid into the main reactor to carry out the chlorination reaction in the step (1); The reaction in the pre-reactor is carried out at atmospheric pressure or higher than atmospheric pressure; Preferably, the partial chlorination reaction is carried out under photocatalysis. The light source for the photocatalysis is, for example, visible light or ultraviolet light, preferably ultraviolet light.

4. The method according to claim 3, wherein The partial chlorination reaction is carried out in one pre-reactor or multiple pre-reactors connected in series; Each of the pre-reactors is respectively connected to a gas-liquid separation tank. The reaction feed liquid output from the pre-reactor is sent to the gas-liquid separation tank for gas-liquid separation, and a liquid phase part and a gas phase part are obtained; When the partial chlorination reaction is carried out in one pre-reactor, the liquid phase part separated from the reaction feed liquid output from the pre-reactor by the gas-liquid separation tank is used as the pre-reaction feed liquid and introduced into the main reactor; When the partial chlorination reaction is carried out in multiple pre-reactors connected in series, the liquid phase part separated from the reaction feed liquid output from the upper-stage pre-reactor by the gas-liquid separation tank is sent to the next-stage pre-reactor for continuous reaction, and the liquid phase part separated from the reaction feed liquid output from the last-stage pre-reactor by the gas-liquid separation tank is used as the pre-reaction feed liquid and introduced into the main reactor; preferably, chlorine gas is introduced into each pre-reactor; Preferably, the gas phase part separated in the gas-liquid separation tank is sent to a tail gas absorption tower for treatment; Preferably, the pre-reactor is a kettle-type, tower-type or tube-type reactor, preferably a tube-type reactor, more preferably a microchannel reactor.

5. The method according to claim 4, wherein When the partial chlorination reaction is carried out in a plurality of pre-reactors connected in series, the reaction pressure of the upper-stage pre-reactor is equal to or higher than the reaction pressure of the lower-stage pre-reactor; preferably, the reaction temperature of the upper-stage pre-reactor is higher than the reaction temperature of the lower-stage pre-reactor; Preferably, the reaction pressure of each pre-reactor is higher than the pressure of the gas-liquid separation tank for separating the reaction feed liquid of the corresponding pre-reactor.

6. The method according to any one of claims 3-5, characterized in that, The reaction in the pre-reactor is carried out under pressurized conditions, preferably 0.1-2 MpaA; Preferably, the reaction temperature in the pre-reactor is 60-120 °C, preferably 60-100 °C, more preferably 60-90 °C; preferably, in the pre-reaction stage, the reaction temperature of the pre-reactor is not lower than the reaction temperature of the main reactor, and preferably the reaction temperature of at least one pre-reactor is higher than the reaction temperature of the main reactor; Preferably, the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be <50%, preferably <40%, further preferably <30%, and more preferably <20%; Preferably, the pre-reactor is a microchannel reactor, and preferably the total conversion rate of ethylene carbonate in the pre-reaction stage is controlled to be <20%, and more preferably <15%.

7. The method according to any one of claims 3 to 6, characterized in that, In the pre-reactor and the main reactor, the total liquid phase residence time is 0.5-8 h.

8. The method according to any one of claims 1 to 7, characterized in that, In step (2), the operating conditions of the distillation column include: The column bottom pressure is 30-1000 PaA, the column bottom temperature is 30-90 °C, and the reflux ratio is 1-10:

1.

9. The method according to any one of claims 1-8, characterized in that, The gaseous product obtained at the top of the distillation column in step (2) is condensed to obtain a crude product; The crude product is crystallized to obtain a product of chloroethyl carbonate; Preferably, the crystallization is melt crystallization, and preferably the crystallization temperature is 10-30 °C; Preferably, the residual gas phase obtained after the gaseous product is condensed is sent to a tail gas absorption tower for treatment.

10. The method according to any one of claims 1-9, characterized in that The molar ratio of the total amount of ethylene carbonate used to the total amount of chlorine used is 1:1.05-1.5, preferably 1.05-1.1.

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