Synthesis process of battery grade ethyl methyl carbonate / diethyl carbonate

Abstract

The invention discloses a battery grade methyl ethyl carbonate / diethyl carbonate synthesis process, which adopts a transesterification method, and dimethyl carbonate (DMC) and ethanol react under the catalysis of sodium methoxide to generate methyl ethyl carbonate (EMC), diethyl carbonate (DEC) and byproduct methanol. High-purity battery-grade EMC and DEC products are obtained through the steps of reactive distillation, azeotrope separation, methanol refining, catalyst carbonization removal, crude EMC / DEC separation, EMC light component removal, industrial-grade EMC refining, battery-grade EMC refining, industrial-grade DEC refining, battery-grade DEC refining and the like. The method has the advantages of simple process flow, low energy consumption, easiness in product separation, high product purity and the like, and is suitable for large-scale production of battery-grade carbonate products.

Description

Technical Field

[0001] The present invention specifically relates to a synthesis process of battery-grade ethyl methyl carbonate / diethyl carbonate (EMC / DEC), belonging to the field of chemical production. Technical Background

[0002] Both ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are green and environmentally friendly chemical products, with excellent thermal conductivity and electrochemical stability. Their asymmetric structure and small steric hindrance can improve the solubility of lithium salts, thereby increasing the energy density and discharge capacity of batteries. They have been widely used as ideal solvents for lithium battery electrolytes. With the rapid development of the lithium battery industry, the application demand for EMC and DEC in lithium battery solvents is also increasing continuously.

[0003] Currently, the main methods for synthesizing EMC and DEC are phosgene method, oxidative carbonylation method, and transesterification method. The phosgene method uses highly toxic phosgene as raw material and generates hydrogen chloride that seriously corrodes equipment, presenting serious environmental pollution problems and has been phased out by the industry; the oxidative carbonylation method has harsh reaction conditions, low yield, and high production cost, with great limitations in industrialization; the transesterification method uses non-toxic dimethyl carbonate (DMC) and ethanol as raw materials, and undergoes transesterification reaction under the action of a catalyst to produce EMC and DEC. This method can not only solve the problem of overcapacity of DMC in the current market, but also has the advantages of simple process flow, mild reaction conditions, low production cost, and recyclability of by-product methanol and raw materials, and is a relatively ideal industrial production method. Summary of the Invention

[0004] The present invention aims to provide a safe, reliable, energy-saving, efficient, high-product-yield, and low-production-cost synthesis process of battery-grade ethyl methyl carbonate / diethyl carbonate (EMC / DEC) in view of the deficiencies of the existing processes.

[0005] Technical Solution: The synthesis process of battery-grade ethyl methyl carbonate / diethyl carbonate (EMC / DEC) according to the present invention is achieved through the following steps:

[0006] (1) Reactive distillation: DMC, the overhead material from the DMC refining tower, a catalyst, and ethanol enter the reactive distillation tower and are mixed for reaction. The azeotrope of methanol (ME) and dimethyl carbonate (DMC) obtained at the top of the tower is sent to the DMC refining tower after condensation, and the bottom crude material is sent to the catalyst carbonization tank;

[0007] (2) Azeotrope separation: The overhead material of the DMC refining tower is sent to the methanol refining tower for methanol refining, and the bottom material is sent back to the reactive distillation tower for re-reaction;

[0008] (3) Methanol refining: The material obtained from the top of the methanol refining column is condensed and then sent back to the DMC refining column, and the material at the bottom of the column is taken out as a by-product.

[0009] (4) Catalyst carbonization removal: Steam and carbon dioxide are introduced into the catalyst carbonization tank, and the obtained material is filtered and removed through a filter to obtain a by-product sodium carbonate (purity ≥ 98.8%), and the filtrate is sent to the crude EMC / DEC separation column for refining.

[0010] (5) Crude ethyl methyl carbonate / diethyl carbonate (EMC / DEC) separation: The filtrate from the catalyst carbonization tank is sent to the crude EMC / DEC separation column for refining. The mixed material obtained from the top of the column is condensed and then sent to the EMC light component removal column. The crude DEC at the bottom of the crude EMC / DEC separation column is sent to the industrial-grade DEC refining column.

[0011] (6) EMC light component removal: The material from the top of the crude EMC / DEC separation column is sent to the EMC light component removal column to remove light components. The mixed material of dimethyl carbonate (DMC), ethanol, and a small amount of methanol at the top of the column is condensed and then sent to the reactive distillation column for further reaction. The crude EMC at the bottom of the EMC light component removal column is sent to the industrial-grade EMC refining column.

[0012] (7) Industrial-grade ethyl methyl carbonate (EMC) refining: The material at the top of the industrial-grade EMC refining column is condensed and then sent back to the EMC light component removal column. The side-stream EMC is sent to the battery-grade EMC refining column through side-stream extraction. The EMC at the bottom of the industrial-grade EMC refining column is returned to the crude EMC / DEC separation column.

[0013] (8) Battery-grade ethyl methyl carbonate (EMC) refining: The EMC at the top and bottom of the battery-grade EMC refining column is cooled and then sent back to the EMC light component removal column. The side-stream extraction is the battery-grade ethyl methyl carbonate (EMC) (purity ≥ 99.99%) product.

[0014] (9) Industrial-grade diethyl carbonate (DEC) refining: The DEC at the top of the industrial-grade DEC refining column is condensed and then sent back to the crude EMC / DEC separation column. The side-stream DEC is sent to the battery-grade DEC refining column through side-stream extraction. The DEC at the bottom of the column is taken out as an industrial-grade DEC (purity ≥ 99.9%) by-product.

[0015] (10) Battery-grade diethyl carbonate (DEC) refining: The DEC at the top of the battery-grade DEC refining column is condensed and then sent back to the crude EMC / DEC separation column. The side-stream extraction is the battery-grade diethyl carbonate (DEC) (purity ≥ 99.99%) product.

[0016] Among them, in step (1), the top pressure of the reactive distillation column is -0.05 to 0.1 MPaG, the top temperature is 40 to 75 °C, and the bottom temperature is 80 to 145 °C; the feed molar ratio of ethanol to dimethyl carbonate (DMC) in the reactive distillation column is (1.02 to 1.4):1; the catalyst used is a methanol solution containing sodium methoxide, and the mass fraction of sodium methoxide is 10 to 40%.

[0017] Preferably, in step (2), the top pressure of the DMC refining column is 0.3 to 0.6 MPaG, the top temperature is 95 to 125 °C, and the bottom temperature is 140 to 180 °C.

[0018] In step (3), the top pressure of the methanol refining column is 0 to 0.05 MPaG, the top temperature is 55 to 70 °C, and the bottom temperature is 60 to 75 °C.

[0019] In step (4), the steam used in the catalyst carbonization tank is 0.5 to 0.8 MPaG; the catalyst filter uses a plate and frame filter press to filter and separate sodium methoxide.

[0020] In step (5), the top pressure of the crude EMC / DEC separation column is 0 to 0.05 MpaG, the top temperature is 90 to 120 °C, and the bottom temperature is 120 to 150 °C.

[0021] In step (6), the top pressure of the EMC light component removal column is 0 to 0.05 MPaG, the top temperature is 80 to 100 °C, and the bottom temperature is 100 to 130 °C.

[0022] In step (7), the top pressure of the industrial-grade EMC refining column is -0.09 to -0.02 MPaG, the top temperature is 50 to 80 °C, and the bottom temperature is 55 to 85 °C.

[0023] In step (8), the top pressure of the battery-grade EMC refining column is -0.09 to -0.02 MPaG, the top temperature is 50 to 80 °C, and the bottom temperature is 55 to 85 °C.

[0024] In step (9), the top pressure of the industrial-grade DEC refining column is -0.09 to -0.02 MPaG, the top temperature is 60 to 100 °C, and the bottom temperature is 65 to 110 °C; in step (10), the top pressure of the battery-grade DEC refining column is -0.09 to -0.02 MPaG, the top temperature is 60 to 100 °C, and the bottom temperature is 65 to 110 °C.

[0025] Beneficial effects: Compared with the prior art, the present application has the following advantages:

[0026] (1) The whole process of the present invention adopts continuous operation, realizes high automation, significantly improves the equipment utilization rate, and the equipment investment per unit product is much lower than that of the traditional technology;

[0027] (2) The present invention combines product synthesis and crude product separation in the same equipment by using reactive distillation technology, eliminating the intermediate operation links in the traditional technology and saving equipment investment and energy consumption;

[0028] (3) The present invention uses pressure swing distillation technology to realize the productization of methanol and recycle the unreacted DMC, avoiding the environmental protection burden of a large amount of waste methanol in the device and improving the effective utilization rate of raw materials;

[0029] (4) By setting a reasonable feed ratio, the present invention improves the primary reaction rate of raw materials, avoiding the problems of low product yield and difficult separation caused by incomplete reaction;

[0030] (5) By setting a reasonable catalyst removal technology, the present invention separates the unreacted catalyst from the product, realizing the maximum utilization of the catalyst and saving production costs;

[0031] (6) By combining multiple towers, the present invention realizes the continuous and fine separation of each product, which is conducive to the stable control of the quality of each product, thus ensuring that the product quality meets the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a process flow diagram of a specific implementation. DETAILED DESCRIPTION OF THE INVENTION

[0033] The following combines the attached Figure 1 The technical solution of the present invention will be elaborated in detail, but the protection scope of the present invention is not limited to the following embodiments.

[0034] As Figure 1 shown, the present invention discloses a synthesis process of battery-grade ethyl methyl carbonate / diethyl carbonate, including the following steps:

[0035] (1) DMC is mixed with the overhead material from the DMC refining tower, catalyst, and ethanol and enters the reactive distillation tower for reaction. The overhead pressure of the reactive distillation tower is -0.05 to 0.1 MPaG, the overhead temperature is 40 to 75 °C, the bottom temperature is 80 to 145 °C. The overhead azeotrope of methanol (ME) and dimethyl carbonate (DMC) is condensed and sent to the DMC refining tower, and the bottom crude material is sent to the catalyst carbonization tank;

[0036] (2) The azeotrope from the overhead of the reactive distillation tower and the overhead material from the methanol refining tower enter the DMC refining tower for refining. The overhead pressure of the DMC refining tower is 0.3 to 0.6 MPaG, the overhead temperature is 95 to 125 °C, the bottom temperature is 140 to 180 °C. The overhead material is sent to the methanol refining tower for methanol refining, and the bottom material is sent back to the reactive distillation tower for further reaction;

[0037] (3) The top pressure of the methanol refining tower is 0 - 0.05 MPaG, the top temperature is 55 - 70 °C, the bottom temperature is 60 - 75 °C. The top mainly contains methanol and a small amount of dimethyl carbonate (DMC), which is sent back to the DMC refining tower after passing through the condenser. The bottom material is mainly methanol (purity ≥ 99.9%) and is taken out as a by-product.

[0038] (4) A small amount of steam and carbon dioxide are introduced into the catalyst carbonization tank, and the sodium methoxide catalyst is carbonized into sodium carbonate with relatively low solubility, which is removed by filtration through a filter to obtain the by-product sodium carbonate (purity ≥ 98.8%). The filtrate is sent to the crude EMC / DEC separation tower.

[0039] (5) The top pressure of the crude EMC / DEC separation tower is 0 - 0.05 MPaG, the top temperature is 90 - 120 °C, the bottom temperature is 120 - 150 °C. The mixed material of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethanol and trace methanol obtained at the top is sent to the EMC light component removal tower after condensation. The crude DEC at the bottom is sent to the DEC refining tower.

[0040] (6) The top pressure of the EMC light component removal tower is 0 - 0.05 MPaG, the top temperature is 80 - 100 °C, the bottom temperature is 100 - 130 °C. The mixed material of dimethyl carbonate (DMC), ethanol and a small amount of methanol at the top is sent to the reactive distillation tower for further reaction after condensation. The crude EMC at the bottom is sent to the industrial - grade EMC refining tower.

[0041] (7) The top pressure of the industrial - grade EMC refining tower is - 0.09 - - 0.02 MPaG, the top temperature is 50 - 80 °C, the bottom temperature is 55 - 85 °C. The EMC at the top is sent back to the EMC light component removal tower after condensation. The EMC at the bottom is returned to the crude EMC / DEC separation tower. The side - line EMC is sent to the battery - grade EMC refining tower through side - draw.

[0042] (8) The top pressure of the battery - grade EMC refining tower is - 0.09 - - 0.02 MPaG, the top temperature is 50 - 80 °C, the bottom temperature is 55 - 85 °C. The EMC at the top and the EMC at the bottom are sent back to the EMC light component removal tower after cooling. The side - draw product is battery - grade ethyl methyl carbonate (EMC) (purity ≥ 99.99%).

[0043] (9) The bottom material of the crude EMC / DEC separation tower is sent to the industrial-grade DEC refining tower for refining. The top pressure of the industrial-grade DEC refining tower is -0.09 to -0.02 MPaG, the top temperature is 60 to 100 °C, the bottom temperature is 65 to 110 °C. The DEC at the top is condensed and sent back to the crude EMC / DEC separation tower. The side-line DEC is sent to the battery-grade DEC refining tower after side-stream extraction, and the DEC at the bottom is taken out as a by-product (purity ≥ 99.9%).

[0044] (10) The top pressure of the battery-grade DEC refining tower is -0.09 to -0.02 MPaG, the top temperature is 60 to 100 °C, the bottom temperature is 65 to 110 °C. The DEC at the top is condensed and sent back to the crude EMC / DEC separation tower, and the side-stream extraction is the battery-grade diethyl carbonate (DEC) (purity ≥ 99.99%) product.

[0045] The technical solution of the present application will be described below through specific embodiments.

[0046] Example 1

[0047] DMC is mixed with the top material of the DMC refining tower, a methanol solution of 25 wt% sodium methoxide, and ethanol in a reactive distillation column and then reacts. The feed molar ratio of ethanol to DMC is 1.2:1. The top pressure of the reactive distillation column is 0.02 MPaG, the top temperature is 65 °C, the bottom temperature is 90 °C. The top azeotrope of methanol (ME) and dimethyl carbonate (DMC) is condensed and sent to the DMC refining tower, and the bottom crude material is sent to the catalyst carbonization tank. The top pressure of the DMC refining tower is 0.5 MPaG, the top temperature is 118 °C, the bottom temperature is 152 °C. The top material is sent to the methanol refining tower for methanol refining, and the bottom material is sent back to the reactive distillation column for further reaction; the top pressure of the methanol refining tower is atmospheric pressure, the top temperature is 64 °C, the bottom temperature is 68 °C. The top is mainly methanol and a small amount of dimethyl carbonate (DMC), which is sent back to the DMC refining tower after passing through a condenser, and the bottom material is methanol (purity 99.93%) taken out as a by-product; 0.5 MPaG steam and carbon dioxide are introduced into the catalyst carbonization tank, and the sodium methoxide catalyst is carbonized into sodium carbonate with a lower solubility and removed by filtration through a plate and frame filter press to obtain the by-product sodium carbonate (purity 98.8%), and the filtrate is sent to the crude EMC / DEC separation tower.

[0048] The top pressure of the crude EMC / DEC separation tower is 0.02 MPaG, the top temperature is 102 °C, the bottom temperature is 134 °C. The mixed material of methyl ethyl carbonate (EMC), dimethyl carbonate (DMC), ethanol, and trace methanol obtained at the top is condensed and sent to the EMC light-component removal tower, and the bottom DEC crude product is sent to the industrial-grade DEC refining tower.

[0049] The top pressure of the EMC light-off tower is 0.02 MPaG, the top temperature is 92 °C, and the bottom temperature is 113 °C. The mixed material of dimethyl carbonate (DMC), ethanol, and a small amount of methanol at the top of the tower is sent to the reactive distillation column for further reaction after condensation. The crude EMC at the bottom of the tower is sent to the industrial-grade EMC purification tower; the top pressure of the industrial-grade EMC purification tower is -0.08 MPaG, the top temperature is 62 °C, and the bottom temperature is 68 °C. The EMC at the top of the tower is sent back to the EMC light-off tower after condensation. The EMC at the bottom returns to the crude EMC / DEC separation tower, and the side-stream EMC is sent to the battery-grade EMC purification tower through side-stream extraction; the top pressure of the battery-grade EMC purification tower is -0.08 MPaG, the top temperature is 62 °C, and the bottom temperature is 68 °C. The EMC at the top and the EMC at the bottom of the tower are sent back to the EMC light-off tower after cooling, and the side-stream product is the battery-grade ethylene methyl carbonate (EMC) (purity 99.99%).

[0050] The top pressure of the industrial-grade DEC purification tower is -0.08 MPaG, the top temperature is 79 °C, and the bottom temperature is 88 °C. The DEC at the top of the tower is sent back to the crude EMC / DEC separation tower after condensation. The side-stream DEC is sent to the battery-grade DEC purification tower through side-stream extraction, and the DEC at the bottom is taken out as a by-product (purity 99.9%); the top pressure of the battery-grade DEC purification tower is -0.08 MPaG, the top temperature is 78 °C, and the bottom temperature is 90 °C. The DEC at the top of the tower is sent back to the crude EMC / DEC separation tower after condensation, and the side-stream product is the battery-grade diethyl carbonate (DEC) (purity 99.99%).

[0051] Example 2

[0052] DMC is mixed with the overhead material from the DMC refining column, a methanol solution of 25 wt% sodium methoxide, and ethanol and then reacts in a reactive distillation column. The feed molar ratio of ethanol to DMC is 1.2:1. The pressure at the top of the reactive distillation column is 0.04 MPaG, the top temperature is 70 °C, the bottom temperature is 95 °C. The azeotrope of methanol (ME) and dimethyl carbonate (DMC) at the top of the column is sent to the DMC refining column after condensation, and the bottom crude material is sent to the catalyst carbonization tank; the pressure at the top of the DMC refining column is 0.55 MPaG, the top temperature is 120 °C, the bottom temperature is 155 °C. The overhead material is sent to the methanol refining column for methanol refining, and the bottom material is sent back to the reactive distillation column for further reaction; the pressure at the top of the methanol refining column is atmospheric pressure, the top temperature is 64 °C, the bottom temperature is 66 °C. The top mainly contains methanol and a small amount of dimethyl carbonate (DMC), which is sent back to the DMC refining column after condensation, and the bottom material is methanol (purity 99.95%) and is taken out as a by-product; a small amount of steam at 0.5 MPaG and carbon dioxide is introduced into the catalyst carbonization tank, and the sodium methoxide catalyst is carbonized into sodium carbonate with lower solubility, which is removed by filtration through a plate and frame filter press to obtain the by-product sodium carbonate (purity 98.8%), and the filtrate is sent to the crude EMC / DEC separation column; the pressure at the top of the crude EMC / DEC separation column is 0.04 MPaG, the top temperature is 108 °C, the bottom temperature is 138 °C. The mixed material of ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), ethanol, and trace methanol obtained at the top of the column is sent to the EMC light component removal column after condensation, and the crude DEC at the bottom is sent to the DEC refining column; the pressure at the top of the EMC light component removal column is 0.01 MPaG, the top temperature is 90 °C, the bottom temperature is 110 °C. The mixed material of dimethyl carbonate (DMC), ethanol, and a small amount of methanol at the top of the column is sent to the reactive distillation column for further reaction after condensation, and the crude EMC at the bottom is sent to the industrial-grade EMC refining column; the pressure at the top of the industrial-grade EMC refining column is -0.06 MPaG, the top temperature is 79 °C, the bottom temperature is 83 °C. The EMC at the top of the column is sent back to the EMC light component removal column after condensation, and the bottom EMC is returned to the crude EMC / DEC separation column, and the side-stream EMC is sent to the battery-grade EMC refining column through side-stream extraction; the pressure at the top of the battery-grade EMC refining column is -0.06 MPaG, the top temperature is 79 °C, the bottom temperature is 82 °C. The EMC at the top of the column and the EMC at the bottom are sent back to the EMC light component removal column after cooling, and the side-stream extraction is the battery-grade ethyl methyl carbonate (EMC) (purity 99.99%) product; the pressure at the top of the industrial-grade DEC refining column is -0.06 MPaG, the top temperature is 97 °C, the bottom temperature is 105 °C. The DEC at the top of the column is sent back to the crude EMC / DEC separation column after condensation, and the side-stream DEC is sent to the battery-grade DEC refining column through side-stream extraction, and the bottom DEC is taken out as an industrial-grade DEC (purity 99.9%) by-product; the pressure at the top of the battery-grade DEC refining column is -0.06 MPaG, the top temperature of the tower is 95 °C, the bottom temperature of the tower is 105 °C. The DEC at the top of the tower is sent back to the crude EMC / DEC separation tower after condensation, and the product taken out from the side line is battery-grade diethyl carbonate (DEC) (purity 99.99%).

[0053] Table 1 Consumption Quota Table of Main Raw and Auxiliary Materials and Utilities

[0054]

[0055]

[0056] The above is a detailed description of a synthesis process of battery-grade ethyl methyl carbonate / diethyl carbonate (EMC / DEC) provided by the present invention, aiming to enable those skilled in the art to understand the content of the present invention and implement it. According to the idea of the embodiments of the present invention, there will be changes or improvements in the specific implementation manner and application scope. Therefore, the content of this specification should not be regarded as a limitation to the present invention.

Claims

1. A battery-grade ethyl methyl carbonate / diethyl carbonate synthesis process, characterized in that: The following steps are involved: (1) Reactive distillation: DMC, the material from the top of the DMC refining tower, the catalyst, and ethanol are mixed in the reactive distillation tower for reaction. The methanol and DMC azeotrope obtained from the top of the tower is condensed and sent to the DMC refining tower. The crude material at the bottom of the tower is sent to the catalyst carbonization tank. (2) Azeotrope separation: The material at the top of the DMC refining tower is sent to the methanol refining tower for methanol refining, and the material at the bottom of the tower is sent back to the reactive distillation tower for further reaction; (3) Methanol refining: The material obtained from the top of the methanol refining tower is condensed and sent back to the DMC refining tower, and the material at the bottom of the tower is taken out as a by-product; (4) Catalyst carbonization removal: Steam and carbon dioxide are introduced into the catalyst carbonization tank, and the obtained material is filtered and removed through a filter to obtain sodium carbonate as a by-product. The filtrate is sent to the crude EMC / DEC separation tower for refining; (5) Crude ethyl methyl carbonate / diethyl carbonate separation: The filtrate from the catalyst carbonization tank is sent to the crude EMC / DEC separation tower for refining. The mixed material obtained at the top of the tower is condensed and sent to the EMC light removal tower. The crude DEC product at the bottom of the crude EMC / DEC separation tower is sent to the industrial-grade DEC refining tower. (6) Ethyl methyl carbonate light removal: The top material from the crude EMC / DEC separation tower is sent to the EMC light removal tower to remove light components. The DMC, ethanol and a small amount of methanol mixture at the top of the tower are condensed and sent to the reactive distillation tower to continue the reaction. The EMC crude product at the bottom of the EMC light removal tower is sent to the industrial-grade EMC refining tower. (7) Refining of industrial-grade ethyl methyl carbonate: The material at the top of the industrial-grade EMC refining tower is sent back to the EMC light removal tower after condensation, the side line EMC is sent to the battery-grade EMC refining tower through side sampling, and the EMC at the bottom of the industrial-grade EMC refining tower is returned to the crude EMC / DEC separation tower; (8) Refining of battery-grade ethyl methyl carbonate: The EMC at the top and bottom of the battery-grade EMC refining tower are cooled and sent back to the EMC light removal tower, and the side line is produced as a battery-grade ethyl methyl carbonate product; (9) Refining of industrial-grade diethyl carbonate: The DEC at the top of the industrial-grade DEC refining tower is condensed and sent back to the crude EMC / DEC separation tower. The side-line DEC is sent to the battery-grade DEC refining tower after side extraction. The DEC at the bottom of the tower is extracted as an industrial-grade DEC by-product. (10) Refining of battery-grade diethyl carbonate: The DEC at the top of the battery-grade DEC refining tower is condensed and sent back to the crude EMC / DEC separation tower, and the battery-grade diethyl carbonate product is taken out from the side line.

2. The process according to claim 1, characterized in that: In step (1), the top pressure of the reaction distillation tower is -0.05~0.1MPaG, the top temperature is 40~75°C, and the bottom temperature is 80~145°C; the feed molar ratio of ethanol to DMC in the reaction distillation tower is (1.02~1.4):1; the catalyst used is a methanol solution containing sodium methoxide, and the mass fraction of sodium methoxide is 10~40%.

3. The process according to claim 1, characterized in that: In step (2), the top pressure of the DMC refining tower is 0.3-0.6 MPaG, the top temperature is 95-125°C, and the bottom temperature is 140-180°C.

4. The process according to claim 1, characterized in that: In step (3), the top pressure of the methanol refining tower is 0-0.05 MPaG, the top temperature is 55-70°C, and the bottom temperature is 60-75°C.

5. The process according to claim 1, characterized in that: In step (4), the steam used in the catalyst carbonization tank is 0.5-0.8 MPaG; the catalyst filter uses a plate and frame filter press to filter and separate the sodium methoxide.

6. The process according to claim 1, characterized in that: In step (5), the top pressure of the crude EMC / DEC separation tower is 0-0.05 MPaG, the top temperature is 90-120°C, and the bottom temperature is 120-150°C.

7. The process according to claim 1, characterized in that: In step (6), the top pressure of the EMC light removal tower is 0-0.05 MPaG, the top temperature is 80-100°C, and the bottom temperature is 100-130°C.

8. The process according to claim 1, characterized in that: In step (7), the top pressure of the industrial-grade EMC refining tower is -0.09~-0.02MPaG, the top temperature is 50~80°C, and the bottom temperature is 55~85°C.

9. The process according to claim 1, characterized in that: In step (8), the top pressure of the battery-grade EMC refining tower is -0.09~-0.02MPaG, the top temperature is 50~80°C, and the bottom temperature is 55~85°C.

10. The process according to claim 1, characterized in that: In step (9), the top pressure of the industrial-grade DEC refining tower is -0.09~-0.02MPaG, the top temperature is 60~100℃, and the bottom temperature is 65~110℃; in step (10), the top pressure of the battery-grade DEC refining tower is -0.09~-0.02MPaG, the top temperature is 60~100℃, and the bottom temperature is 65~110℃.

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