A method for improving the yield of synthetic vinylene carbonate

Abstract

The present invention proposes a method for improving the yield of synthesized vinylene carbonate, comprising the following steps: (1) in an organic solvent, using vinyl chlorocarbonate as a raw material, adding an organic amine dechlorination catalyst to carry out a dechlorination reaction, and adding an inhibitor solution after the dechlorination reaction is carried out for a period of time, and continuing the reaction to prepare a vinylene carbonate crude product; (2) extracting and separating the vinylene carbonate crude product through hot water to obtain a vinylene carbonate product; wherein the inhibitor solution is prepared in advance by dissolving the inhibitor in the solvent, and the inhibitor is one or more of o-hydroxybenzoic acid, m-hydroxybenzoic acid, gentisic acid, and pyrogallol acid. The method according to the present invention can increase the crude yield of VC products synthesized by an intermittent method by ≥95%, and the crude yield of VC products synthesized by a micro-reaction continuously by ≥98%. The present invention is green, economical, safe and efficient, and can significantly improve the current synthesis process level of vinylene carbonate.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery electrolyte additive synthesis, in particular to a method for improving the yield of intermittent and continuous synthesis of vinylene carbonate. Background Art

[0002] As an organic film-forming additive and overcharge protection additive for lithium-ion battery electrolyte, vinylene carbonate (VC) has good high and low temperature performance and anti-flatulence function. With the rapid growth of lithium-ion battery applications in electric vehicles, energy storage and other fields, the performance and stability of lithium-ion batteries have become the focus of attention. A small amount of VC can preferentially reduce and decompose on the carbon negative electrode during the battery's charge and discharge process to form an excellent SEI film, effectively inhibiting the continuous decomposition of solvent molecules on the electrode surface, thereby improving the performance of the carbon negative electrode, and further increasing the energy density and service life of lithium-ion batteries. In addition, it can also be used as a monomer of functional polymer materials, a fine chemical intermediate, etc., so it has broad application prospects.

[0003] At present, in the process of industrial intermittent or continuous synthesis of VC, triethylamine (Et3N) is usually used as a dechlorinating agent to dechlorinate chloroethylene carbonate (CEC) to generate VC and byproduct triethylamine hydrochloride (Et3N-HCl) precipitation, with mild reaction conditions, simple operation, and green environmental protection. Patent DE-A19955944 reported that ethylene carbonate was used as a reaction solvent, and the reaction was carried out at 60°C for 1.5 hours, and the product VC yield was 73%, which effectively shortened the reaction time, but the melting point of ethylene carbonate was high, and the subsequent separation process was complicated. US2009 / 0234141 adopts a solvent-free or small amount of solvent method, that is, VC itself is used as a solvent to facilitate the separation of the product, and the product yield is 73%, which solves the problem that the product VC is adsorbed on triethylamine hydrochloride and is difficult to purify from the reaction mixture, but the VC concentration is too high, which will lead to the intensification of VC polymerization and reduce the VC yield. CN 108864031A uses a mixture of p-benzoquinone and 2,6-di-tert-butyl-4-methylphenol as a novel inhibitor in the process of triethylamine-catalyzed CEC dechlorination, which inhibits polymerization side reactions, improves the reaction selectivity, and the crude product yield is 69%. CN 101407508A proposes using a mixture of esters, ethers, and hydrocarbons as an organic solvent and using BHT as an inhibitor, and the crude VC product yield is 65%. CN 101161647A uses propylene carbonate as a solvent and continuously adds triethylamine, and the crude VC product yield is 60%. In addition, there are also other solid catalysts and gas-phase catalysts for CEC dechlorination to synthesize VC, such as US 2009 / 0176997, which reports the direct dechlorination of CEC in a tubular reactor to prepare VC using solid ZnCl2 as a catalyst, with a yield of 69%, but the reaction temperature is high, the product selectivity is low, and the equipment and production conditions are harsh. CN 105384720A reports a method of using high-purity ammonia as a dechlorinating agent, introducing ammonia for 3 hours at 70° C., and obtaining a crude vinylene carbonate with a yield of 82%.

[0004] In terms of the continuous synthesis of VC, CN 112174928A uses CEC and Et3N as raw materials, dimethyl carbonate as solvent, and uses a multi-reactor series reactor to continuously produce VC. The feed flow rate of the mixture is preferably 0.05-0.8 m / s, and the VC yield after vacuum distillation is 96.5%. CN 106749755B reports an enhanced mass transfer microchannel reactor for preparing VC. The specific process includes: 0.2 mL / min CEC and dimethyl carbonate mixed liquid and 0.4 mL / min Et3N are synchronously input into the microchannel, the residence time is 250 seconds at 40°C, and the yield of the product after vacuum distillation is 94%. This method has a high product yield, but the processing volume is small, and triethylamine hydrochloride is easy to block the microchannel, which is not conducive to industrial production.

[0005] The intermittent and continuous synthesis processes of VC reported so far are mostly different in raw material ratios and solvents used, but the crude yield of VC before vacuum distillation is only between 60% and 80%. Due to the lack of a deep understanding of the side reaction mechanism of VC polymerization, the types of inhibitors currently used are all structural inhibitors, which have unsatisfactory inhibitor effects, unstable products, difficult to break through yield levels, and difficult product separation. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for improving the yield of synthesized vinylene carbonate, so that the batch yield of vinylene carbonate product is ≥95% and the continuous yield is ≥98%.

[0007] The technical solution of the present invention is as follows: A method for improving the yield of vinylene carbonate comprises the following steps:

[0008] (1) In an organic solvent, chloroethylene carbonate is used as a raw material, an organic amine dechlorination catalyst is added to carry out a dechlorination reaction, and after the dechlorination reaction is carried out for a period of time, an inhibitor solution is added, and the reaction is continued to prepare a crude vinylene carbonate product;

[0009] (2) extracting and separating the crude vinylene carbonate product through hot water to obtain a vinylene carbonate product;

[0010] The inhibitor solution is prepared in advance by dissolving the inhibitor in the solvent, and the inhibitor is one or more of o-hydroxybenzoic acid, m-hydroxybenzoic acid, gentisic acid, and pyrogallol acid.

[0011] The present invention is further configured such that the solvent is selected from one of chloroform, dimethyl carbonate or acetonitrile.

[0012] The present invention is further configured such that the polymerization inhibitor consists of two parts of organic acids, namely pyrogallol acid and at least one of o-hydroxybenzoic acid, m-hydroxybenzoic acid or gentisic acid, and the molar ratio of the two parts is 1:7-10.

[0013] The present invention is further configured such that the dechlorination catalyst is selected from one or more of triethylamine, tripropylamine, diethylamine, triethanolamine, isopropanolamine, pyridine, picoline, and lutidine.

[0014] Preferably, the dechlorination catalyst is one or more of triethylamine, tripropylamine and picoline.

[0015] The present invention is further configured such that, in step (1), the dechlorination reaction can be an intermittent synthesis or a continuous synthesis in a micro-reaction channel.

[0016] The present invention is further configured that when the dechlorination reaction adopts intermittent synthesis, the reaction temperature is 50-70°C, the reaction time is 2-10h, the volume ratio of the chloroethylene carbonate to the solvent is 1:2-5, the molar ratio of the chloroethylene carbonate to the dechlorination catalyst is 1:1-3, the molar amount of the inhibitor is 5-25% of the molar amount of the dechlorination catalyst, the mass fraction of the inhibitor solution is 30-50%, and the inhibitor solution is continuously added in the time period of 0.5h to 2.5h after the start of the reaction until the end of the reaction time.

[0017] Preferably, the reaction temperature is 60°C and the reaction time is 8 hours.

[0018] Preferably, the volume ratio of the chloroethylene carbonate to the solvent is 1:2.5.

[0019] Preferably, the molar ratio of the chloroethylene carbonate to the dechlorination catalyst is 1:1.5.

[0020] The present invention is further configured that when the solvent is acetonitrile, the molar amount of the inhibitor is 10-25% of the molar amount of the dechlorination catalyst, and the inhibitor solution is continuously added at a rate of 0.25-0.35wt% / min from the beginning of the reaction for 20-40 minutes until the end of the reaction time;

[0021] When the solvent is chloroform or dimethyl carbonate, the molar amount of the inhibitor is 5-10% of the molar amount of the dechlorination catalyst, and the inhibitor solution is continuously added at a rate of 0.05-0.15wt% / min from the beginning of the reaction for 50-70 minutes until the end of the reaction time.

[0022] The present invention is further configured that when the dechlorination reaction adopts continuous synthesis in a micro-reaction channel, a chloroethylene carbonate solution, a dechlorination catalyst solution and an inhibitor solution are pre-prepared with acetonitrile as a solvent, wherein in the chloroethylene carbonate solution, the molar ratio of the chloroethylene carbonate to acetonitrile is 1:3-8, in the dechlorination catalyst solution, the volume ratio of the dechlorination catalyst to acetonitrile is 1:1-3, the mass fraction of the inhibitor solution is 30-50%, the molar amount of the inhibitor is 1-3% of the molar amount of the dechlorination catalyst, and the molar ratio of the dechlorination catalyst to the chloroethylene carbonate is 1-1.5:1.

[0023] Preferably, in the ethylene chlorocarbonate solution, the molar ratio of ethylene chlorocarbonate to acetonitrile is 1:5.

[0024] Preferably, in the dechlorination catalyst solution, the volume ratio of the dechlorination catalyst to acetonitrile is 1:1.5.

[0025] Preferably, the molar ratio of the dechlorination catalyst to ethylene chlorocarbonate is 1.05:1.

[0026] The present invention is further configured such that the reaction temperature in the micro-reaction channel is 50-70° C., the reaction time is 0.5-1h, during the reaction, the chloroethylene carbonate solution is a feed with a flow rate of 4-10mL / min, the dechlorination catalyst solution is another feed with a flow rate of 4-8mL / min, and during the reaction residence time of 10-20min, the inhibitor solution is cut into the reaction channel through a three-way mixer with a flow rate of 0.5-1mL / min.

[0027] Preferably, the reaction temperature is 70° C. and the reaction time is 30 to 40 min.

[0028] Preferably, the inhibitor solution is introduced through a three-way mixer during the reaction residence time of 15 minutes.

[0029] The present invention is further configured that in step (2), the crude vinylene carbonate product is extracted and separated in hot water at 60-75°C, the separated oil phase is the vinylene carbonate product insoluble in hot water, the aqueous phase is an aqueous solution including an organic amine salt byproduct and an inhibitor, and the separated aqueous solution is crystallized by cooling to separate the inhibitor precipitate for recycling. In the above hot water extraction process, if the extraction temperature is too low, the organic amine salt byproduct is easy to precipitate, and if the temperature is too high, it may cause the vinylene carbonate to polymerize, thereby affecting the yield.

[0030] Furthermore, the separated aqueous solution is cooled, and during the cooling process to 30-35° C., the inhibitor precipitate is separated in time and further recycled through acidification treatment.

[0031] The present invention has the following beneficial effects:

[0032] (1) In the process of promoting the dechlorination reaction by using an organic amine as a dechlorination catalyst, a suitable organic acid polymerization inhibitor is added. The organic acid polymerization inhibitor has a proton affinity stronger than that of triethylamine, and the inhibition energy barrier is lower than the main reaction energy barrier, thereby efficiently realizing the inhibition process of vinylene carbonate.

[0033] (2) The present invention achieves intermittent and continuous high-yield synthesis of vinylene carbonate by optimizing the amount and time of adding the polymerization inhibitor, ensuring that the VC yield of the intermittent method is ≥95% and the yield of the continuous method is ≥98%, both of which are better than the crude product yield of synthetic VC currently reported at home and abroad, and the added organic polymerization inhibitor can be recycled by simple extraction separation. DETAILED DESCRIPTION

[0034] The technical scheme in the embodiments of the present invention will be further described in detail below. It should be understood that the described embodiments are only further explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. Based on the embodiments of the present invention, ordinary technicians in the field can make non-essential improvements and modifications to the present invention without creative work, including further expansion and amplification of the intermittent and continuous synthesis methods, and the use of inhibitors similar to the phenolic acid combination method, which are all within the scope of protection of the present invention.

[0035] Example 1 Intermittent Synthesis Process

[0036] The reaction device is an intermittent reactor, dimethyl carbonate is used as the reaction solvent, and the dechlorination catalyst is triethylamine, wherein the molar ratio of triethylamine to the raw material chloroethylene carbonate (CEC) is 1.5:1, and the volume ratio of dimethyl carbonate to CEC is 2.5:1; the reaction temperature is 60°C, the reaction time is 8 hours, and the yield of the crude product vinylene carbonate (VC) is 75%, and no inhibitor is added in the process. .

[0037] Example 2 Intermittent Synthesis Process

[0038] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 60°C, the dechlorination catalyst is triethylamine, the molar ratio of triethylamine to CEC is 1.5:1, the solvent is dimethyl carbonate, the volume ratio of triethylamine to CEC is 2.5:1, and the reaction time is 8 hours. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, the molar ratio is 10:1; the inhibitor is dissolved in dimethyl carbonate, the mass fraction is 30%. The inhibitor solution is prepared according to the molar amount of the inhibitor as 10% of triethylamine, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.1wt% / min after the reaction for 1 hour until the reaction time ends. The crude product after the reaction is dissolved in 70°C hot water for extraction and separation, and the yield of VC is 96.8%.

[0039] Example 3 Intermittent Synthesis Process

[0040] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 70°C, triethylamine and tripropylamine are mixed in a molar ratio of 1:1 as an organic amine dechlorination catalyst, the molar ratio of the dechlorination catalyst to CEC is 2:1, chloroform is selected as the solvent, the volume ratio of chloroform to CEC is 5:1, and the reaction time is 5 hours. The inhibitor is a combination of gentisic acid and pyrogallol acid, the molar ratio is 7:1; the organic inhibitor is dissolved in chloroform, the mass fraction is 50%. The inhibitor solution is prepared according to 5% of the molar amount of the inhibitor as the organic amine dechlorination catalyst, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.1wt% / min after the reaction for 1 hour until the reaction time ends. The crude product after the reaction is dissolved in 70°C hot water for extraction and separation, and the yield of VC is 97.2%.

[0041] Example 4 Intermittent Synthesis Process

[0042] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 50°C, triethylamine, isopropanolamine, and picoline are mixed in a molar ratio of 3:1:1 as an organic amine dechlorination catalyst, the molar ratio of the dechlorination catalyst to CEC is 3:1, and acetonitrile is selected as the solvent, the volume ratio of which to CEC is 2:1, and the reaction time is 10 hours. The inhibitor is a combination of o-hydroxybenzoic acid and pyrogallol acid, the molar ratio is 9:1; the organic inhibitor is dissolved in acetonitrile, the mass fraction is 40%. The inhibitor solution is prepared according to the inhibitor being 8% of the molar amount of the organic amine, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.3wt% / min after the reaction for 1 hour until the reaction time ends. The crude product after the reaction is dissolved in 70°C hot water for extraction and separation, and the yield of VC is 95.2%.

[0043] Example 5 Intermittent Synthesis Process

[0044] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 60°C, triethylamine, diethylamine, and triethanolamine are mixed in a molar ratio of 4:5:1 as an organic amine dechlorination catalyst, the molar ratio of the dechlorination catalyst to CEC is 1:1, and acetonitrile is selected as the solvent, the volume ratio of which to CEC is 4:1, and the reaction time is 2 hours. The inhibitor is a combination of o-hydroxybenzoic acid, m-hydroxybenzoic acid and pyrogallol acid, the molar ratio is 3:6:1; the organic inhibitor is dissolved in acetonitrile, the mass fraction is 45%. The inhibitor solution is prepared according to 10% of the molar amount of the inhibitor for the organic amine dechlorination catalyst, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.3wt% / min after the reaction for 1 hour until the reaction time ends. The crude product after the reaction is dissolved in 70°C hot water for extraction and separation, and the yield of VC is 96.0%.

[0045] Comparative Example 1 Intermittent Synthesis Process

[0046] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 60°C, the dechlorination catalyst is triethylamine, the molar ratio of triethylamine to CEC is 1.5:1, the solvent is dimethyl carbonate, the volume ratio of triethylamine to CEC is 2.5:1, and the reaction time is 8 hours. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, the molar ratio is 10:1; the inhibitor is dissolved in dimethyl carbonate, the mass fraction is 30%. The inhibitor solution is prepared according to the molar amount of the inhibitor of triethylamine of 10%, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.1wt% / min after the reaction for 20 minutes until the reaction time ends. The crude product after the reaction is dissolved in 70°C hot water for extraction and separation, and the yield of VC is 77.3%.

[0047] Comparative Example 2 Intermittent Synthesis Process

[0048] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 60°C, the dechlorination catalyst is triethylamine, the molar ratio of triethylamine to CEC is 1.5:1, the solvent is dimethyl carbonate, the volume ratio of triethylamine to CEC is 2.5:1, and the reaction time is 8 hours. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, the molar ratio is 10:1; the organic inhibitor is dissolved in dimethyl carbonate, the mass fraction is 30%. The inhibitor solution is prepared according to the molar amount of organic inhibitor as 10% of triethylamine, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.5wt% / min after the reaction for 20 minutes until the reaction time ends. The crude product after the reaction is dissolved in 60°C hot water for extraction and separation, and the yield of VC is 70.4%.

[0049] Comparative Example 3 Intermittent Synthesis Process

[0050] The reaction device is an intermittent reactor, the reaction temperature of the intermittent synthesis is 60°C, the dechlorination catalyst is triethylamine, the molar ratio of triethylamine to CEC is 1.5:1, the solvent is dimethyl carbonate, the volume ratio of triethylamine to CEC is 2.5:1, and the reaction time is 8 hours. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, the molar ratio is 10:1; the organic inhibitor is dissolved in dimethyl carbonate, the mass fraction is 30%. The inhibitor solution is prepared according to the molar amount of organic inhibitor as 10% of triethylamine, and the inhibitor solution is added dropwise to the reaction system at a rate of 0.5wt% / min after the reaction for 3 hours until the reaction time ends. The crude product after the reaction is dissolved in 75°C hot water for extraction and separation, and the yield of VC is 78.8%.

[0051] Example 6 Micro-reaction channel synthesis process

[0052] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the micro-reaction continuous synthesis process, the volume ratio of CEC to acetonitrile solvent is 1:5; the organic amine dechlorination catalyst is a mixture of triethylamine and tripropylamine in a molar ratio of 7:3, and the molar ratio of organic amine to CEC is 1.05:1; the volume ratio of organic amine to acetonitrile solvent is 1:1.5; CEC solution is used as one feed with a feed flow rate of 4 mL / min, and the organic amine solution is another feed with a feed flow rate of 4 mL / min. The reaction temperature is 60°C, the reaction time is 40 minutes, and the yield of crude product VC is 86%. No inhibitor is added during the process.

[0053] Example 7 Micro-reaction channel synthesis process

[0054] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent is 1:5; the organic amine dechlorination catalyst is a mixture of triethylamine and tripropylamine in a molar ratio of 7:3, and the molar ratio of organic amine to CEC is 1.05:1; the volume ratio of organic amine to acetonitrile solvent is 1:1.5; CEC solution is used as one feed, the feed flow rate is 4 mL / min, and the organic amine solution is another feed, the feed flow rate is 4 mL / min, the reaction temperature is 70°C, and the reaction time is 40 minutes. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, with a molar ratio of 10:1; the inhibitor is dissolved in acetonitrile, with a mass fraction of 30%. The inhibitor solution is prepared according to the inhibitor being 2% of the molar amount of triethylamine, and the organic inhibitor solution is cut into the reaction residence time period of 15 minutes through a three-way mixer, with a flow rate of 1 mL / min. The crude product at the reaction outlet was dissolved in 60°C hot water for extraction and separation, and the yield of VC was 99.1%.

[0055] Example 8 Micro-reaction channel synthesis process

[0056] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent in the CEC solution is 1:8; the organic amine dechlorination catalyst is triethylamine, and the molar ratio of triethylamine to CEC is 1.5:1; the volume ratio of triethylamine to acetonitrile solvent in the triethylamine solution is 1:3; the CEC solution is used as one feed, the feed flow rate is 10 mL / min, the organic amine solution is another feed, the feed flow rate is 8 mL / min, the reaction temperature is 50 ° C, and the reaction time is 1 hour. The inhibitor is a combination of gentisic acid and pyrogallol acid, with a molar ratio of 7:1; the organic inhibitor is dissolved in acetonitrile, with a mass fraction of 50%. The inhibitor solution is prepared according to the inhibitor being 3% of the molar amount of triethylamine, and the organic inhibitor solution is cut into the reaction residence time period of 15 minutes through a three-way mixer, with a flow rate of 1 mL / min. The crude product at the reaction outlet was dissolved in 70°C hot water for extraction and separation, and the yield of VC was 98.2%.

[0057] Example 9 Micro-reaction channel synthesis process

[0058] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent in the CEC solution is 1:3; the organic amine dechlorination catalyst is a mixture of triethylamine and tripropylamine in a molar ratio of 1:1, and the molar ratio of organic amine to CEC is 1:1; the volume ratio of organic amine to acetonitrile solvent in the organic amine solution is 1:1; CEC solution is used as one feed, the feed flow rate is 5 mL / min, and the organic amine solution is another feed, the feed flow rate is 4.5 mL / min, the reaction temperature is 70°C, and the reaction time is 30 minutes. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, with a molar ratio of 10:1; the organic inhibitor is dissolved in acetonitrile, with a mass fraction of 30%. The inhibitor solution is prepared according to the inhibitor being 1% of the molar amount of triethylamine, and the organic inhibitor solution is cut into the reaction residence time period of 15 minutes through a three-way mixer, with a flow rate of 0.5 mL / min. The crude product at the reaction outlet was dissolved in 70°C hot water for extraction and separation, and the yield of VC was 98.8%.

[0059] Example 10 Micro-reaction channel synthesis process

[0060] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent in the CEC solution is 1:6; the organic amine dechlorination catalyst is a mixture of triethylamine and triethanolamine in a molar ratio of 4:1, and the molar ratio of organic amine to CEC is 1.2:1; the volume ratio of organic amine to acetonitrile solvent in the organic amine solution is 1:2; CEC solution is used as one feed, the feed flow rate is 4 mL / min, and the organic amine solution is another feed, the feed flow rate is 4 mL / min, the reaction temperature is 70°C, and the reaction time is 50 minutes. The inhibitor is a combination of m-hydroxybenzoic acid, o-hydroxybenzoic acid and pyrogallol acid, with a molar ratio of 6:3:1; the organic inhibitor is dissolved in acetonitrile, with a mass fraction of 40%. The inhibitor solution was prepared according to the molar dosage of 3% of triethylamine, and the organic inhibitor solution was introduced through a three-way mixer at a flow rate of 0.8 mL / min during the reaction residence time of 15 minutes. The crude product at the reaction outlet was dissolved in 70° C. hot water for extraction and separation, and the yield of VC was 98.4%.

[0061] Comparative Example 4 Micro-reaction channel synthesis process

[0062] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent is 1:5; the organic amine dechlorination catalyst is a mixture of triethylamine and tripropylamine in a molar ratio of 7:3, and the molar ratio of organic amine to CEC is 1.05:1; the volume ratio of organic amine to acetonitrile solvent is 1:1.5; CEC solution is used as one feed, the feed flow rate is 4 mL / min, and the organic amine solution is another feed, the feed flow rate is 4 mL / min, the reaction temperature is 70°C, and the reaction time is 40 minutes. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, with a molar ratio of 10:1; the organic inhibitor is dissolved in acetonitrile, with a mass fraction of 30%. The inhibitor solution is prepared according to the molar amount of triethylamine used as the organic inhibitor, and the organic inhibitor solution is cut into the reaction residence time period of 5 minutes through a three-way mixer, with a flow rate of 1 mL / min. The crude product at the reaction outlet was dissolved in 60°C hot water for extraction and separation, and the yield of VC was 80%.

[0063] Comparative Example 5 Micro-reaction channel synthesis process

[0064] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is a polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent is 1:5; the organic amine dechlorination catalyst is a mixture of triethylamine and tripropylamine in a molar ratio of 7:3, and the molar ratio of organic amine to CEC is 1.05:1; the volume ratio of organic amine to acetonitrile solvent is 1:1.5; CEC solution is used as one feed, the feed flow rate is 4 mL / min, and the organic amine solution is another feed, the feed flow rate is 4 mL / min, the reaction temperature is 70°C, and the reaction time is 40 minutes. The inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, with a molar ratio of 10:1; the organic inhibitor is dissolved in acetonitrile, with a mass fraction of 30%. The inhibitor solution is prepared according to the inhibitor being 3% of the molar amount of triethylamine, and the organic inhibitor solution is cut into the reaction residence time period of 30 minutes through a three-way mixer, with a flow rate of 1 mL / min. The crude product at the reaction outlet was dissolved in 70°C hot water for extraction and separation, and the yield of VC was 84%.

[0065] Comparative Example 6 Micro-reaction channel synthesis process

[0066] The size of the micro-reaction channel is 1.8 mm, and the material of the reaction channel is polytetrafluoroethylene tube. During the continuous synthesis of the micro-reaction, the volume ratio of CEC to acetonitrile solvent is 1:5; the organic amine is a mixture of triethylamine and tripropylamine in a molar ratio of 7:3, and the molar ratio of organic amine to CEC is 1.05:1; the volume ratio of organic amine to acetonitrile solvent is 1:1.5; CEC solution is used as one feed, the feed flow rate is 4 mL / min, and the organic amine solution is another feed, the feed flow rate is 4 mL / min, the reaction temperature is 70 ° C, and the reaction time is 40 minutes. The organic inhibitor is a combination of m-hydroxybenzoic acid and pyrogallol acid, with a molar ratio of 10:1; the organic inhibitor is dissolved in acetonitrile, with a mass fraction of 30%. The inhibitor solution is prepared according to the molar amount of triethylamine as 1% of the organic inhibitor, and the organic inhibitor solution is cut into the reaction residence time of 1 minute through a three-way mixer, with a flow rate of 1 mL / min. The crude product at the reaction outlet was dissolved in 75°C hot water for extraction and separation, and the yield of VC was 80%.

[0067] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for increasing the yield of vinylene carbonate, characterized in that: The steps include: (1) In an organic solvent, chloroethylene carbonate is used as a raw material, an organic amine dechlorination catalyst is added to carry out a dechlorination reaction, and after the dechlorination reaction has been carried out for a period of time, an inhibitor solution is added, and the reaction is continued to prepare a crude vinylene carbonate product; (2) extracting and separating the crude vinylene carbonate product by hot water to obtain a vinylene carbonate product; The inhibitor solution is prepared in advance by dissolving the inhibitor in the solvent, wherein the inhibitor is one or more of o-hydroxybenzoic acid, m-hydroxybenzoic acid, gentisic acid, and pyrogallol acid; and the solvent is selected from one of chloroform, dimethyl carbonate, or acetonitrile; In step (1), the dechlorination reaction is a batch synthesis or a micro-reaction channel continuous synthesis. When the dechlorination reaction is a batch synthesis, the reaction temperature is 50-70 ° C, the reaction time is 2-10 hours, the molar amount of the inhibitor is 5-25% of the molar amount of the dechlorination catalyst, the mass fraction of the inhibitor solution is 30-50%, and the inhibitor solution is continuously added from 0.5h to 2.5h after the reaction starts until the end of the reaction time; when the dechlorination reaction is a batch synthesis, the volume ratio of the chloroethylene carbonate to the solvent is 1:2-5, and the molar ratio of the chloroethylene carbonate to the dechlorination catalyst is 1:1-3; Alternatively, when the dechlorination reaction is continuously synthesized using a micro-reaction channel, the reaction temperature in the micro-reaction channel is 50-70°C, the reaction time is 0.5-1h, during the reaction, the chloroethylene carbonate solution is fed as one stream with a flow rate of 4-10 mL / min, the dechlorination catalyst solution is fed as another stream with a flow rate of 4-8 mL / min, and during the reaction residence time of 10-20 min, the inhibitor solution is cut into the reaction mixture through a three-way mixer with a flow rate of 0.5-1 mL / min; when the dechlorination reaction is continuously synthesized in a micro-reaction channel, acetonitrile is used as a solvent to prepare a chloroethylene carbonate solution, a dechlorination catalyst solution and an inhibitor solution in advance, wherein the molar ratio of the chloroethylene carbonate to acetonitrile in the chloroethylene carbonate solution is 1:3-8, the volume ratio of the dechlorination catalyst to acetonitrile in the dechlorination catalyst solution is 1:1-3, and the mass fraction of the inhibitor solution is 30-50%; the molar amount of the inhibitor is 1-3% of the molar amount of the dechlorination catalyst, and the molar ratio of the dechlorination catalyst to the chloroethylene carbonate is 1-1.5:1; In step (2), the crude vinylene carbonate product is extracted and separated in hot water at 60-75°C, the separated oil phase is the vinylene carbonate product, and the aqueous phase is an aqueous solution including an organic amine salt by-product and an inhibitor. The separated aqueous solution is crystallized by cooling to separate the inhibitor precipitate for recycling.

2. A method for increasing the yield of vinylene carbonate according to claim 1, characterized in that: The polymerization inhibitor consists of two parts of organic acids, which are pyrogallol acid and one of o-hydroxybenzoic acid, m-hydroxybenzoic acid or gentisic acid, and the molar ratio of the two parts is 1:7-10.

3. A method for increasing the yield of vinylene carbonate according to claim 1, characterized in that: The dechlorination catalyst is one or more of triethylamine, tripropylamine, diethylamine, triethanolamine, isopropanolamine, pyridine, picoline, and lutidine.

4. A method for increasing the yield of vinylene carbonate according to claim 3, characterized in that: The dechlorination catalyst is one or more of triethylamine, tripropylamine and picoline.

5. A method for increasing the yield of vinylene carbonate according to claim 1, characterized in that: When the solvent is acetonitrile, the molar amount of the inhibitor is 10-25% of the molar amount of the dechlorination catalyst, and the inhibitor solution is continuously added at a rate of 0.25-0.35wt% / min from the beginning of the reaction for 20-40 minutes until the end of the reaction time; When the solvent is chloroform or dimethyl carbonate, the molar amount of the inhibitor is 5-10% of the molar amount of the dechlorination catalyst, and the inhibitor solution is continuously added at a rate of 0.05-0.15 wt % / min from the start of the reaction for 50-70 minutes until the end of the reaction time.

6. A method for increasing the yield of vinylene carbonate according to claim 1, characterized in that: When the dechlorination reaction is continuously synthesized using a micro-reaction channel, the molar ratio of the chloroethylene carbonate to acetonitrile in the chloroethylene carbonate solution is 1:5; the volume ratio of the dechlorination catalyst to acetonitrile in the dechlorination catalyst solution is 1:1.5; the mass fraction of the inhibitor solution is 30-50%; The molar ratio of the dechlorination catalyst to the chloroethylene carbonate is 1.05:

1.

7. A method for increasing the yield of vinylene carbonate according to claim 1, characterized in that: The reaction temperature in the micro-reaction channel is 70°C, and the reaction time is 30-40 minutes.