Methyl ethyl carbonate synthesis reaction rectification method taking ethyl acetate as raw material
By using ethyl acetate instead of ethanol during the synthesis of methyl ethyl carbonate and separating the product by using the reaction distillation process, the problems of complex production process and high energy consumption in the existing technology are solved, and efficient and low-cost production of methyl ethyl carbonate is achieved.
Patent Information
- Application Number
- CN202411681145.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-22
- Publication Date
- 2025-02-25
AI Technical Summary
The existing methyl ethyl carbonate synthesis methods have problems such as complex production processes and high energy consumption, especially in transesterification reactions. Due to the existence of binary azeotropes, the separation process is complex, resulting in high production costs.
Ethyl acetate was used instead of ethanol and transesterification reaction with dimethyl carbonate. A methyl ethyl carbonate synthesis reaction distillation method was developed using ethyl acetate as the raw material. The product methyl ethyl carbonate and the by-product methyl acetate were separated in situ by using the reaction distillation process, breaking the equilibrium of chemical reactions and improving the reaction conversion rate.
It significantly reduces the energy consumption and cost of methyl ethyl carbonate production, improves the yield and selectivity of methyl ethyl carbonate, and realizes greening and low-carbonization of methyl ethyl carbonate synthesis.
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Figure CN119504440A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of ethyl methyl carbonate preparation, in particular to a ethyl methyl carbonate synthesis reaction distillation method using ethyl acetate as a raw material. Background Art
[0002] Ethyl methyl carbonate has good electrochemical properties, low toxicity, and low volatility. It is a highly promising organic solvent and the main solvent for lithium-ion battery electrolytes. With the rapid development of the lithium-ion battery industry, the demand for ethyl methyl carbonate continues to increase. Therefore, it is of great significance to develop an efficient, environmentally friendly, and economical method for synthesizing ethyl methyl carbonate.
[0003] The current synthesis methods of ethyl methyl carbonate mainly include phosgene method, oxidative carbonylation method and transesterification method. Phosgene method and oxidative carbonylation method use phosgene and carbon monoxide as raw materials respectively, which have great safety hazards and high production costs. The reactants used in the transesterification method are alcohols and esters, which have the advantages of safe raw materials, mild reaction conditions, easy control and less environmental pollution. It is the most promising method for preparing ethyl methyl carbonate. However, the commonly used ethanol and dimethyl carbonate alcohol-esterification reaction process has three pairs of binary azeotropes of dimethyl carbonate-methanol, dimethyl carbonate-ethanol and ethyl methyl carbonate-ethanol, and the subsequent separation process is complicated and the production cost is high. Therefore, it is urgent to develop a new method for producing ethyl methyl carbonate. The products of the transesterification method of dimethyl carbonate and ethyl acetate are ethyl methyl carbonate, diethyl carbonate and methyl acetate, and no azeotropes are produced. In addition, the method has the advantages of mild reaction conditions, high atomic utilization rate and simple process flow, which greatly reduces the production cost and is a potential suitable method for producing ethyl methyl carbonate.
[0004] For the transesterification reaction system of dimethyl carbonate and ethyl acetate, the conversion rate of the fixed bed reaction process is low due to the limitation of chemical equilibrium, which increases the energy consumption of subsequent separation. In order to achieve a thorough reaction of one of the reactants, a new production process is required. The reaction system is analyzed, and its by-product is methyl acetate with a boiling point of 56.8°C. The boiling points of the reactants dimethyl carbonate and ethyl acetate are 77 and 90°C respectively, and the boiling points of the products ethyl methyl carbonate and diethyl carbonate are 107 and 121°C respectively. The boiling points of the two reactants are between the products and by-products. Therefore, the reactive distillation process is suitable for this reaction system, which can move the product ethyl methyl carbonate and the by-product methyl acetate out of the reaction zone in-situ to break the chemical reaction equilibrium, thereby significantly improving the reaction conversion rate and reducing energy consumption.
[0005] Developing a suitable reaction distillation process is another key to ensure the efficient production of ethyl methyl carbonate. In the reaction distillation process of transesterification between dimethyl carbonate and ethyl acetate, if the reaction between dimethyl carbonate and ethyl acetate is not carried out thoroughly, the subsequent separation energy consumption of the product is high. In order to achieve a thorough reaction, if ethyl acetate is excessive and dimethyl carbonate is reacted thoroughly, ethyl methyl carbonate is easy to further react with excess ethyl acetate during the reaction process to reduce the selectivity of ethyl methyl carbonate; on the contrary, if dimethyl carbonate is excessive, it is conducive to improving the selectivity of ethyl methyl carbonate, but too much dimethyl carbonate will also increase the subsequent separation energy consumption. Therefore, based on the developed solid alkaline catalyst, the development of a matching reaction distillation coupling technology can not only ensure the high selectivity of ethyl methyl carbonate, but also achieve a high conversion rate of ethyl acetate. This is the key to improving the efficiency of the ethyl methyl carbonate synthesis process, ensuring the quality of ethyl methyl carbonate products, and ensuring the sustainable development of the ethyl methyl carbonate industry. Summary of the invention
[0006] Therefore, in view of the above problems, the present invention provides a method for synthesizing ethyl methyl carbonate by reactive distillation using ethyl acetate as a raw material, so as to solve the problems of complex production process and high energy consumption in the current mainstream method of preparing ethyl methyl carbonate by ester exchange using ethanol as a raw material and dimethyl carbonate.
[0007] To achieve the above object, the present invention adopts the following technical solutions:
[0008] A reactive distillation method for synthesizing ethyl methyl carbonate using ethyl acetate as a raw material specifically comprises the following steps:
[0009] (1) The reaction distillation tower comprises a reaction section arranged in the middle section, a distillation section arranged above the reaction section, and a stripping section arranged below the reaction section, the reaction section is filled with a solid catalyst, the raw material ethyl acetate is fed from the lower part of the reaction section of the reaction distillation tower, and dimethyl carbonate is fed from the upper part of the reaction section of the reaction distillation tower;
[0010] (2) the methyl acetate material extracted from the top of the reactive distillation tower passes through the top condenser, a portion of which is sent to the top reflux port as reflux liquid, and a portion is extracted, and dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate are extracted from the bottom of the tower;
[0011] (3) the material from the reactor of the reaction distillation tower is sent to a dimethyl carbonate recovery tower, the light component dimethyl carbonate extracted from the top of the tower is returned to the reaction distillation tower, and ethyl methyl carbonate and diethyl carbonate are extracted from the reactor;
[0012] (4) The material from the bottom of the dimethyl carbonate recovery tower is sent to a coarse fractionation tower, and the light component ethyl methyl carbonate is taken out from the top of the tower, and diethyl carbonate is taken out from the bottom of the tower.
[0013] The solid catalyst in the above steps is one or two combined catalysts of alkaline resin containing methanol anions and ethanol anions, zinc and magnesium solid bases supported by activated alumina, which are mixed or single-filled.
[0014] In the above steps, the feed flow rate of dimethyl carbonate is 1000kg / h-8500kg / h, and the molar ratio of dimethyl carbonate to ethyl acetate is 1:1-3:1.
[0015] In the above steps, the amount of solid catalyst in the reaction section of the reaction distillation tower is 20-150 times the mass of dimethyl carbonate fed per hour.
[0016] In the above steps, the top reflux ratio of the reactive distillation tower is controlled at 2.0-10.0.
[0017] In the above steps, the number of theoretical plates of the stripping section of the reactive distillation tower is 10-50, the number of theoretical plates of the distillation section is 4-20, and the solid catalyst is 8-20 meters high.
[0018] In the above steps, the dimethyl carbonate recovery tower adopts atmospheric distillation, the reflux ratio is 1.0-5.0, the tower top temperature is 90°C, and the tower bottom temperature is 107-128°C.
[0019] In the above steps, the crude fraction tower adopts atmospheric distillation, the reflux ratio is 1.0-3.0, the tower top temperature is 107°C, and the tower bottom temperature is 127-130°C.
[0020] Ethyl methyl carbonate is the main raw material of lithium ion battery electrolyte. It is mainly prepared by dimethyl carbonate and ethanol in the ester exchange reaction distillation process. The reaction system has three pairs of binary azeotropes of dimethyl carbonate-methanol, dimethyl carbonate-ethanol, and ethyl methyl carbonate-ethanol, which makes the subsequent separation process complicated and the production cost high. For this reason, the inventor uses ethyl acetate instead of ethanol to carry out ester exchange reaction with dimethyl carbonate. The by-product of the reaction is methyl acetate, and there is no azeotrope, which completely solves the problems of high separation energy consumption and high production cost in the traditional ethyl methyl carbonate production process. By optimizing the reaction and separation process, a methyl ethyl carbonate synthesis reaction distillation technology using ethyl acetate as raw material has been developed, which achieves high conversion rate and high selectivity while reducing the energy consumption and cost of ethyl methyl carbonate production.
[0021] By adopting the above technical solution, the beneficial effects of the present invention are:
[0022] 1. The present invention uses ethyl acetate instead of ethanol as the raw material for synthesizing ethyl methyl carbonate through ester exchange, which can completely solve the problems of high separation energy consumption and high production cost in the traditional production process of ethyl methyl carbonate and significantly reduce the production cost of ethyl methyl carbonate.
[0023] 2. Based on the new synthesis method of ethyl methyl carbonate, a new reaction distillation process for the synthesis of ethyl methyl carbonate is developed, which can effectively improve the yield of ethyl methyl carbonate, significantly reduce the unit consumption and energy consumption of ethyl methyl carbonate, and realize the green and low-carbon synthesis of ethyl methyl carbonate. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 The present invention is a process flow chart of the reaction and distillation of ethyl methyl carbonate synthesis using ethyl acetate as raw material.
[0025] Figure 2 is the yield of ethyl methyl carbonate in the ester exchange reaction of ethyl acetate and dimethyl carbonate under different catalysts. DETAILED DESCRIPTION
[0026] The embodiments of the present invention are:
[0027] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.
[0028] Example 1
[0029] D201 strong base anion exchange resin and sodium methoxide were mixed in a mass ratio of 10:1, and then added into a methanol solvent of the same mass as that of D201 strong base anion exchange resin. The mixture was exchanged at room temperature for 24 hours, and then washed with 3 times the mass of methanol for 3 times, and dried in a constant temperature drying oven at 50°C for 24 hours to obtain D201 strong base anion exchange resin-methanol anion catalyst (D201-CH3O - ).
[0030] D201 strong base anion exchange resin is an anion exchange resin with a quaternary ammonium group [-N(CH3)3OH] on a macroporous styrene-divinylbenzene copolymer. It is a well-known product in the prior art and can be directly purchased in the existing market, so it will not be described in detail here.
[0031] Example 2
[0032] D201 strong base anion exchange resin and sodium ethoxide were mixed in a mass ratio of 10:1, and then added into an ethanol solvent of the same mass as that of D201 strong base anion exchange resin. The mixture was exchanged at room temperature for 24 hours, and then washed with 3 times the mass of ethanol for 3 times, and dried in a constant temperature drying oven at 50°C for 24 hours to obtain D201 strong base anion exchange resin-ethanol anion catalyst (D201-CH3CH2O - ).
[0033] Example 3
[0034] Alumina particles and zinc nitrate were mixed in a mass ratio of 10:1 and added into an ethanol solvent of the same mass as the alumina particles, exchanged at 50°C for 24 hours, then washed with 3 times the mass of ethanol for 3 times, and the above operation was repeated three times. The mixture was placed in a constant temperature drying oven at 50°C and dried for 24 hours, and calcined at 500°C for 5 hours to obtain a zinc-loaded alumina particle catalyst (Al2O3-Zn).
[0035] Example 4
[0036] Alumina particles and magnesium nitrate were mixed in a mass ratio of 10:1 and added into an ethanol solvent of the same mass as the alumina particles, exchanged at 50°C for 24 hours, then washed with 3 times the mass of ethanol for 3 times, and the above operation was repeated three times. The mixture was placed in a constant temperature drying oven at 50°C and dried for 24 hours, and calcined at 500°C for 5 hours to obtain a magnesium-loaded alumina particle catalyst (Al2O3-Mg).
[0037] Example 5
[0038] refer to Figure 1 , with different anion exchange resins (D201-CH3O - , D201-CH3CH2O - ), zinc and magnesium solid base supported by activated alumina (Al2O3-Zn, Al2O3-Mg) were used as catalysts for transesterification to synthesize ethyl methyl carbonate. The conditions were temperature 80°C, catalyst dosage 10%wt (dimethyl carbonate), dimethyl carbonate: ethyl acetate = 2:1, and sampling and analysis were performed at 30min, 60min, 120min, and 180min respectively. The relationship between the yield of ethyl methyl carbonate and reaction time under different catalysts is shown in the figure. Figure 2 As shown, the catalysts used showed better catalytic activity in the ester exchange reaction to synthesize ethyl methyl carbonate.
[0039] Example 6
[0040] D201-CH3O - The reaction distillation experiment of transesterification of dimethyl carbonate and ethyl acetate was carried out for the catalyst. The diameter of the reaction distillation tower was 500 mm, with 15 theoretical plates in the distillation section and 20 theoretical plates in the stripping section. D201-CH3O was filled in the middle. - Catalyst, catalyst amount is 100m 3. The feed flow rate of dimethyl carbonate is 2000kg / h, the molar ratio of dimethyl carbonate to ethyl acetate is 2:1, and the reflux ratio at the top of the tower is controlled at 5.0. The dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the dimethyl carbonate recovery tower, the reflux ratio is controlled at 3.0, the top temperature is 90°C, and the bottom temperature is 115°C. The ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the coarse fractionation tower, the reflux ratio is controlled at 2.0, the top temperature is 107°C, the bottom temperature is 127°C, the amount of ethyl methyl carbonate produced from the top of the tower is 1097kg / h, the amount of diethyl carbonate produced from the bottom of the tower is 64kg / h, and the selectivity of ethyl methyl carbonate is 94.5%.
[0041] Example 7
[0042] D201-CH3CH2O - The reaction distillation experiment of transesterification of dimethyl carbonate and ethyl acetate was carried out as a catalyst. The diameter of the reaction distillation tower was 500 mm, with 15 theoretical plates in the distillation section and 20 theoretical plates in the stripping section. D201-CH3CH2O was filled in the middle. - Catalyst, catalyst amount is 120m 3 . The feed flow rate of dimethyl carbonate is 2000kg / h, the molar ratio of dimethyl carbonate to ethyl acetate is 2:1, and the reflux ratio at the top of the tower is controlled at 5.5. The dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the dimethyl carbonate recovery tower, and the reflux ratio is controlled at 3.0, the top temperature is 90°C, and the bottom temperature is 115°C. The ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the coarse fractionation tower, and the reflux ratio is controlled at 2.0, the top temperature is 107°C, the bottom temperature is 127°C, the amount of ethyl methyl carbonate produced from the top of the tower is 1109kg / h, the amount of diethyl carbonate produced from the bottom of the tower is 52kg / h, and the selectivity of ethyl methyl carbonate is 95.5%.
[0043] Example 8
[0044] The reaction distillation experiment of transesterification of dimethyl carbonate and ethyl acetate was carried out with Al2O3-Zn as catalyst. The diameter of the reaction distillation tower was 500 mm, with 15 theoretical plates in the distillation section and 20 theoretical plates in the stripping section. The Al2O3-Zn catalyst was loaded in the middle, and the catalyst amount was 200 m 3. The feed flow rate of dimethyl carbonate is 2000kg / h, the molar ratio of dimethyl carbonate to ethyl acetate is 2.5:1, and the reflux ratio at the top of the tower is controlled at 6.0. The dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the dimethyl carbonate recovery tower, the reflux ratio is controlled at 3.0, the top temperature is 90°C, and the bottom temperature is 115°C. The ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the coarse fractionation tower, the reflux ratio is controlled at 2.0, the top temperature is 107°C, the bottom temperature is 127°C, the amount of ethyl methyl carbonate produced from the top of the tower is 896kg / h, the amount of diethyl carbonate produced from the bottom of the tower is 31kg / h, and the selectivity of ethyl methyl carbonate is 96.6%.
[0045] Example 9
[0046] The reaction distillation experiment of transesterification of dimethyl carbonate and ethyl acetate was carried out with Al2O3-Mg as catalyst. The diameter of the reaction distillation tower was 500 mm, with 15 theoretical plates in the distillation section and 20 theoretical plates in the stripping section. The Al2O3-Mg catalyst was loaded in the middle, and the catalyst amount was 200 m 3 . The feed flow rate of dimethyl carbonate is 2000kg / h, the molar ratio of dimethyl carbonate to ethyl acetate is 2.5:1, and the reflux ratio at the top of the tower is controlled at 6.0. The dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the dimethyl carbonate recovery tower, the reflux ratio is controlled at 3.0, the top temperature is 90°C, and the bottom temperature is 115°C. The ethyl methyl carbonate and diethyl carbonate produced from the bottom of the tower are pumped into the coarse fractionation tower, the reflux ratio is controlled at 2.0, the top temperature is 107°C, the bottom temperature is 127°C, the amount of ethyl methyl carbonate produced from the top of the tower is 896kg / h, the amount of diethyl carbonate produced from the bottom of the tower is 31kg / h, and the selectivity of ethyl methyl carbonate is 96.6%.
[0047] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.
Claims
1. A reactive distillation method for synthesizing ethyl methyl carbonate using ethyl acetate as a raw material, characterized in that: The following steps are involved: (1) The reaction distillation tower comprises a reaction section arranged in the middle section, a distillation section arranged above the reaction section, and a stripping section arranged below the reaction section, the reaction section is filled with a solid catalyst, the raw material ethyl acetate is fed from the lower part of the reaction section of the reaction distillation tower, and dimethyl carbonate is fed from the upper part of the reaction section of the reaction distillation tower; (2) the methyl acetate material extracted from the top of the reactive distillation tower passes through the top condenser, a portion of which is sent to the top reflux port as reflux liquid, and a portion is extracted, and dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate are extracted from the bottom of the tower; (3) the material from the reactor of the reaction distillation tower is sent to a dimethyl carbonate recovery tower, the light component dimethyl carbonate extracted from the top of the tower is returned to the reaction distillation tower, and ethyl methyl carbonate and diethyl carbonate are extracted from the reactor; (4) The material from the bottom of the dimethyl carbonate recovery tower is sent to a coarse fractionation tower, and the light component ethyl methyl carbonate is taken out from the top of the tower, and diethyl carbonate is taken out from the bottom of the tower.
2. A method for synthesizing ethyl methyl carbonate by reactive distillation with ethyl acetate as raw material according to claim 1, characterized in that: The solid catalyst is a mixed or single filled alkaline resin containing methanol anions and ethanol anions, a zinc solid base supported by active alumina, or a combination of any two of the following catalysts.
3. A method for synthesizing ethyl methyl carbonate by reactive distillation with ethyl acetate as raw material according to claim 1, characterized in that: The feed flow rate of dimethyl carbonate is 1000kg / h-8500kg / h, and the molar ratio of dimethyl carbonate to ethyl acetate is 1:1-3:
1.
4. A method for synthesizing ethyl methyl carbonate by reactive distillation with ethyl acetate as raw material according to claim 1, characterized in that: The amount of solid catalyst in the reaction section of the reaction distillation tower is 20-150 times the mass of dimethyl carbonate fed per hour.
5. A method for synthesizing ethyl methyl carbonate by reactive distillation with ethyl acetate as raw material according to claim 1, characterized in that: The top reflux ratio of the reactive distillation tower is controlled at 2.0-10.
0.
6. A reactive distillation method for synthesizing ethyl methyl carbonate using ethyl acetate as a raw material according to claim 1, characterized in that: The number of theoretical plates in the stripping section of the reactive distillation tower is 10-50, the number of theoretical plates in the distillation section is 4-20, and the height of the solid catalyst filled is 8-20 meters.
7. A method for synthesizing ethyl methyl carbonate by reactive distillation with ethyl acetate as raw material according to claim 1, characterized in that: The dimethyl carbonate recovery tower adopts atmospheric distillation, with a reflux ratio of 1.0-5.0, a tower top temperature of 90°C, and a tower bottom temperature of 107-128°C.
8. A reactive distillation method for synthesizing ethyl methyl carbonate using ethyl acetate as a raw material according to claim 1, characterized in that: The crude fraction tower adopts atmospheric distillation, with a reflux ratio of 1.0-3.0, a tower top temperature of 107°C, and a tower bottom temperature of 127-130°C.