Method for synthesizing high-purity methyl butyl carbonate by using sodium methoxide as catalyst
By using sodium methoxide as a catalyst and combining distillation and multi-stage separation technology, the feed ratio and reaction conditions of dimethyl carbonate and n-butanol were optimized, solving the problem of low conversion rate in MBC synthesis and realizing the production of high-purity and high-efficiency methyl butyl carbonate.
Patent Information
- Application Number
- CN202511695449.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-02-10
AI Technical Summary
In existing technologies, carbonate solvents have poor thermal stability and low conversion rates in MBC synthesis reactions, making it difficult to meet the high-performance development requirements of lithium-ion batteries.
Using sodium methoxide as a catalyst, combined with distillation and multi-stage separation technology, and through a reactive distillation column, a light-heavy separation column, and a membrane separation system, the feed ratio and reaction conditions of dimethyl carbonate and n-butanol were optimized to achieve the synthesis of high-purity methyl butyl carbonate.
It improves the conversion rate and purity of MBC, with a single-pass conversion rate of over 90% and a product purity of 99.99%, while reducing separation energy consumption.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of potassium butyl carbonate preparation technology, and in particular to a method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst. Background Technology
[0002] Lithium-ion batteries maintain a dominant position in the global energy storage market due to their superior characteristics such as high energy density, long cycle life, and environmental friendliness. Faced with rapidly growing market demand and increasingly stringent quality standards, developing high-performance battery electrolytes has become a core element in improving the overall performance of lithium-ion batteries.
[0003] Currently, most mainstream electrolyte systems are built around carbonate solvents. Carbonate solvents can be specifically divided into cyclic carbonates, such as ethylene carbonate and propylene carbonate, and linear carbonates, such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Although carbonate solvents are widely used in various battery products, their drawbacks are gradually becoming apparent, with poor thermal stability being a particularly prominent issue. To effectively overcome these challenges and help lithium-ion battery technology advance to a new stage of development, researchers are focusing their research on developing novel electrolyte solvent systems.
[0004] MBC, as an asymmetric linear carbonate, possesses significant advantages such as low volatility, high flash point, and excellent electrochemical stability. Its liquid operating temperature range is wider than that of traditional carbonate solvents, effectively improving battery energy density and safety, especially under extreme environmental conditions, where its performance is superior, making it an ideal solvent for lithium-ion battery electrolytes. Therefore, developing an efficient MBC synthesis process is of paramount strategic importance for advancing lithium-ion battery energy storage technology.
[0005] MBC can be synthesized via transesterification of DMC and n-BuOH. However, this reaction is a reversible series reaction, subject to chemical equilibrium, resulting in a low conversion rate. Improving the conversion rate of MBC and increasing its production capacity has become an urgent technical problem to be solved. Summary of the Invention
[0006] In view of this, the technical problem to be solved by the present invention is to provide a method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst, which achieves high yield and high purity of MBC.
[0007] To address the aforementioned problems, this invention provides a method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst, comprising the following steps:
[0008] Using dimethyl carbonate and n-butanol as raw materials and sodium methoxide as catalyst, high-purity methyl butyl carbonate is produced by distillation and multi-stage separation technology, with dibutyl carbonate as a byproduct.
[0009] The distillation is carried out in a reactive distillation column;
[0010] The reactive distillation column includes: a rectification section, a reaction section, and a stripping section;
[0011] The multi-stage separation includes: a light-heavy separation tower, a dibutyl carbonate tower, and a membrane separation system.
[0012] In some specific embodiments, the method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst includes the following steps:
[0013] Sodium methoxide and n-butanol are fed into the reactive distillation column at the top of the reaction section, while dimethyl carbonate is fed into the reactive distillation column at the bottom of the reaction section. They come into contact with sodium methoxide and n-butanol and undergo transesterification to produce methanol and methyl butyl carbonate.
[0014] The mixture of methanol and unreacted dimethyl carbonate vapor collected from the top of the reactive distillation column is condensed and sent to a membrane separation system to obtain dimethyl carbonate and methanol, respectively.
[0015] The reaction liquid collected from the bottom of the reactive distillation column includes the reaction product methyl butyl carbonate, the byproduct dibutyl carbonate, and residual dimethyl carbonate and n-butanol in the system. The reaction liquid is then fed into a light-heavy separation column, which employs partitioned-wall distillation technology. The column has two outlets at the top: the first outlet collects dimethyl carbonate and n-butanol, and the second outlet collects methyl butyl carbonate. Dibutyl carbonate is collected from the bottom of the light-heavy separation column.
[0016] Preferably, the molar ratio of dimethyl carbonate to n-butanol is 1.2 to 3:1, where the above molar ratio is the molar ratio of the two feeds.
[0017] The preferred amount of sodium methoxide is 0.5% to 5% of the mass of n-butanol, where the above amounts refer to the feed amount of sodium methoxide.
[0018] This invention achieves the co-production of MBC and DBC by adjusting the feed ratio of dimethyl carbonate and n-butanol.
[0019] Preferably, the internal pressure of the reactive distillation column is atmospheric pressure.
[0020] The preferred temperature at the top of the reactive distillation column is 69-73℃.
[0021] The preferred bottom temperature of the reactive distillation column is 115-140℃.
[0022] The theoretical plate number of the reaction section of the reactive distillation column is preferably 10-20, and the temperature of the reaction section is preferably 80-90℃.
[0023] The theoretical plate number of the rectification section of the reactive distillation column is preferably 20-45.
[0024] The theoretical plate number of the stripping section of the reactive distillation column is preferably 10-25.
[0025] The above parameters are designed to facilitate the enrichment of dimethyl carbonate and n-butanol in the reaction section, increasing the concentration of reactants. At the same time, maintaining a suitable reaction temperature is beneficial to improving the conversion rate of the transesterification reaction.
[0026] The mixture of unreacted dimethyl carbonate and methanol as a product vapor is collected from the top of the reactive distillation column. After condensation, it is sent to a membrane separation system. After membrane separation, the dimethyl carbonate is returned to the reactive distillation column as reflux liquid from the top of the column. The methanol obtained by membrane separation with a purity greater than 99.0% can be sold as a product.
[0027] The membrane separation system preferably includes: a membrane separator, a methanol tower, and a dimethyl carbonate distillation tower.
[0028] The membrane in the membrane separation system is preferably an ultrawetting membrane, and water is used as an inducing separator to adjust polarity.
[0029] The superwetting separation membrane is preferably a polytetrafluoroethylene / polyacrylonitrile (PTFE / PAN) composite membrane. The separation layer is made of PTFE, and polyacrylonitrile (PAN) serves as the membrane's supporting material.
[0030] The separation of DMC and MeOH azeotropes uses an ultrawetting separation membrane, which avoids conventional pressure swing distillation and reduces the energy consumption of the separation.
[0031] After membrane separation, the material rich in dimethyl carbonate is separated by the dimethyl carbonate tower. The dimethyl carbonate is then returned to the reactive distillation tower as reflux liquid from the top of the tower. The material rich in methanol is separated by the methanol tower. The methanol with a purity greater than 99.0% can be sold as a product. The water separated from the dimethyl carbonate tower and the methanol tower is recycled within the membrane separation system.
[0032] The reaction liquid collected from the bottom of the reactive distillation column, including methyl butyl carbonate, the byproduct dibutyl carbonate, and residual dimethyl carbonate and n-butanol in the system, is fed into a light-heavy separation column. The light-heavy separation column of this invention employs partitioned-wall distillation technology, with internal partitions dividing the column into a secondary rectification section and a main rectification section, with a common stripping section located below the partitions.
[0033] The secondary distillation section yields unreacted dimethyl carbonate and n-butanol, the main distillation section yields methyl butyl carbonate, and the common stripping section yields dibutyl carbonate and other materials.
[0034] The theoretical plate number of the sub-distillation section is preferably 10-24, with a feed inlet in the middle, and the reflux ratio of the sub-distillation section is preferably 2-6.
[0035] The theoretical plate number of the main rectification section is preferably 20-32, and the reflux ratio of the main rectification section is preferably 4-8.
[0036] The theoretical plate number of the common stripping section is preferably 8-16.
[0037] The above parameter settings facilitate the timely extraction of dimethyl carbonate and n-butanol from the top of the auxiliary column, allowing the enriched dibutyl carbonate to enter the main column as soon as possible, eliminating backmixing and reducing separation energy consumption.
[0038] The secondary rectification section and the main rectification section are each equipped with a top condenser and a product outlet. The first product outlet is connected to the secondary rectification section, and dimethyl carbonate and n-butanol are collected, which can be returned to the middle feed inlet of the reaction section of the reactive distillation column for reuse; the second product outlet is connected to the main rectification section, and methyl butyl carbonate is collected.
[0039] The experimental results show that the purity of the methyl butyl carbonate obtained above can reach 99.99%.
[0040] The separation of multiple groups of components from the bottom of the reactive distillation column is carried out using partitioned wall distillation technology, which can simplify the separation process, reduce multiple evaporations and condensations of components in conventional distillation systems, and reduce separation energy consumption.
[0041] If purity is required, the dibutyl carbonate collected from the bottom of the light-heavy separation tower can be fed into the dibutyl carbonate tower. The dibutyl carbonate product is obtained from the top of the dibutyl carbonate tower, while the material containing sodium methoxide catalyst is obtained from the bottom of the tower and returned to the upper feed port of the reaction section of the reactive distillation tower.
[0042] The dibutyl carbonate tower is preferably a vacuum tower.
[0043] The theoretical plate number of the dibutyl carbonate column is preferably 8-16, with intermediate feed.
[0044] The preferred reflux ratio for the dibutyl carbonate column is 3-6.
[0045] If it is necessary to further improve the purity of dibutyl carbonate, the dibutyl carbonate product obtained from the top of the dibutyl carbonate tower can be fed into the dibutyl carbonate refining tower, and the refined dibutyl carbonate product can be obtained from the bottom of the tower.
[0046] The dibutyl carbonate refining tower is preferably a vacuum tower.
[0047] The theoretical plate number of the dibutyl carbonate refining tower is preferably 16-32.
[0048] The preferred reflux ratio of the dibutyl carbonate refining tower is 2-6.
[0049] The experimental results show that the purity of the dibutyl carbonate obtained above can reach 99.99%.
[0050] The sodium methoxide and dibutyl carbonate materials collected from the bottom of the dibutyl carbonate column are returned to the reactive distillation column. This not only enables the reuse of the catalyst but also suppresses the formation of dibutyl carbonate byproducts and improves the selectivity of methyl butyl carbonate products.
[0051] Figure 1 , Figure 2 This is a schematic diagram of the process flow for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst, as provided in this application.
[0052] The following abbreviations are used for methyl butyl carbonate (MBC), dimethyl carbonate (DMC), dibutyl carbonate (DBC), and n-butanol (n-BuOH).
[0053] like Figure 1 As shown in some specific embodiments, the specific process flow for the reactive distillation synthesis of MBC is as follows: a mixture of n-BuOH and sodium methoxide catalyst, S101, is fed from the top of the reaction section of reactive distillation column T1, while DMC feedstock S102 is fed from the bottom of the reaction section. Under the dual action of distillation and reaction, the methanol generated from the transesterification reaction and the unreacted DMC form a mixture vapor S103, which is condensed by a condenser and then sent to a membrane separation system. The DMC material S202 separated by the membrane is returned to the top of column T1 as reflux.
[0054] The material S104 from the bottom of tower T1 is sent to the light-heavy separation tower T3. The steam from the top of the auxiliary tower T3 is condensed, and part of it is refluxed, while part of the material S301 is sent to the intermediate feed port of the reaction section of T1. The steam from the top of the main tower T3 is condensed, and part of it is refluxed, while part of the material S302 is collected as MBC product.
[0055] The material S303 collected from the bottom of tower T3 is sent to tower T4 of DBC. The steam at the top of the tower is condensed and partially refluxed, while part of the material S401 is collected as DBC product. The material S402 collected from the bottom of the tower is sent to the feed inlet at the top of the reaction section T1.
[0056] When DMC or n-BuOH raw materials contain impurities, and the purity of MBC and DBC products does not reach 99.99%, the following methods can be used: Figure 2 The improved process flow for the reactive distillation synthesis of MBC is shown.
[0057] like Figure 2As shown, the improved process flow is as follows: a mixture of n-BuOH and sodium methoxide catalyst S101 is fed from the top of the reaction section of reactive distillation column T1, while DMC feedstock S102 is fed from the bottom of the reaction section. Under the dual action of distillation and reaction, methanol generated from the transesterification reaction and unreacted DMC form an azeotropic vapor S103, which is condensed by a condenser and sent to the membrane separation system. The DMC material S202 separated by the membrane is returned to the top of column T1 as reflux.
[0058] The material S104 from the bottom of tower T1 is sent to the light-heavy separation tower T3. The steam from the top of the auxiliary tower T3 is condensed, and part of it is refluxed, while part of the material S301 is sent to the intermediate feed port of the reaction section of T1. The steam from the top of the main tower T3 is condensed, and part of it is refluxed, while part of the material S302 is collected as MBC product.
[0059] The material S303 collected from the bottom of tower T3 is sent to tower T4 of DBC. The steam at the top of the tower is condensed and partially refluxed, while part of the material S401 is collected as DBC product. The material S402 collected from the bottom of the tower is sent to the feed inlet at the top of the reaction section T1.
[0060] S302 material is sent to MBC refining tower T5. The steam at the top of the tower is condensed and partially returned, while S501 (mainly light impurities entrained in S302) is extracted. The heavy impurities entrained in S302 are extracted from the bottom of the tower. Qualified MBC is obtained from the side extraction of S503.
[0061] The S401 material is sent to the DBC refining tower T6. After condensation, part of the steam at the top of the tower is returned, and part of it is taken out as S601 (mainly light impurities entrained in S401). The heavy impurities entrained in S401 are taken out from the bottom of the tower. Qualified DBC is obtained from the side-collected S603.
[0062] Compared with existing technologies, this invention discloses a method for synthesizing high-purity MBC and producing DBC as a byproduct via reactive distillation using sodium methoxide as a catalyst. Sodium methoxide and n-BuOH are mixed and fed into a reactive distillation column at the top of the reaction section, while DMC is fed into the bottom of the reaction section. During distillation within the column, DMC undergoes a transesterification reaction after sufficient contact with the catalysts sodium methoxide and n-BuOH. An azeotrope of DMC and methanol is collected from the top of the column, while DMC, MBC, and DBC are collected from the bottom. After passing through a DMC recovery column, a light-heavy separation column, and a DBC product column, MBC and DBC with a purity greater than 99.99% are obtained.
[0063] This invention addresses the limitation of the transesterification reaction of dimethyl carbonate and n-butanol by chemical equilibrium. Using sodium methoxide as a catalyst and reactive distillation technology, it improves the conversion rate of raw materials and the selectivity of products. The single-pass conversion rate of n-BuOH reaches over 90%, and the selectivity of MBC is adjustable. Attached Figure Description
[0064] Figure 1 This is a process flow diagram for the reactive distillation synthesis of MBC according to the present invention. Wherein, T1 is the reactive distillation column, M2 is the membrane separation system, T3 is the light-heavy separation column, and T4 is the DBC column.
[0065] Figure 2 This is a flow chart of the improved process for synthesizing MBC by reactive distillation according to the present invention. Wherein, T1 is the reactive distillation column, M2 is the membrane separation system, T3 is the light-heavy separation column, T4 is the DBC column, T5 is the MBC purification column, and T6 is the DBC purification column. Detailed Implementation
[0066] To further illustrate the present invention, a detailed description is provided below with reference to embodiments. However, it should be understood that these descriptions are merely for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.
[0067] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0068] Example 1
[0069] Fresh n-BuOH and subsequent recycled sodium methoxide catalyst are mixed at a flow rate of 1419.50 kg / hr from the top of the reaction section of reactive distillation column T1. DMC feed at a rate of 1562.5 kg / hr is fed from the bottom of the reaction section. The sodium methoxide feed rate is 1.58% of the n-BuOH mass. The reactive distillation column has 15 theoretical plates in the reactive rectification section, 22 in the rectification section, and 18 in the stripping section. The reactive distillation column operates at atmospheric pressure, with the operating temperature of the reaction section controlled at 84.3℃ and the top temperature at the top of the column at 71.8℃.
[0070] The vapor at the top of the reactive distillation column T1 is condensed, and the condensate S103 has a flow rate of 1214.35 kg / hr. After separation by the membrane separation system, methanol product S201 (595.29 kg / hr) is obtained, and DMC (619.06 kg / hr) is separated and used as reflux S202 for column T1.
[0071] The T3 light-heavy separation column has 16 theoretical plates in the side rectification section, with intermediate feed and a reflux ratio of 4.5; the T3 column's main rectification section has 30 theoretical plates with a reflux ratio of 6; and the common stripping section has 12 theoretical plates. The T3 column's side rectification section produces 1826.19 kg / hr of S301 at the top, the T3 column's main rectification section produces 2143.20 kg / hr of S302 at the top, and the column's bottom produces 243.55 kg / hr of S303.
[0072] The DBC tower T4 operates at a pressure of 0.02 bar, has a theoretical number of 10 plates, uses intermediate feed, has a reflux ratio of 4.5, and produces S401 at a flow rate of 172.19 kg / hr at the top of the tower.
[0073] In this embodiment, the single-pass conversion rate of n-butanol in the reactive distillation column was 90.6%, and the purity of the MBC product was 99.99%.
[0074] The following is some logistics information:
[0075] Table 1 Key Logistics Information
[0076]
[0077] Table 2 Key Logistics Information
[0078]
[0079] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst, comprising the following steps: Using dimethyl carbonate and n-butanol as raw materials and sodium methoxide as catalyst, high-purity methyl butyl carbonate is produced by distillation and multi-stage separation technology, with dibutyl carbonate as a byproduct. The distillation is carried out in a reactive distillation column; The reactive distillation column includes: a rectification section, a reaction section, and a stripping section; The multi-stage separation includes: a light-heavy separation tower, a dibutyl carbonate tower, and a membrane separation system.
2. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 1, characterized in that, Includes the following steps: Sodium methoxide and n-butanol are fed into the reactive distillation column at the top of the reaction section, while dimethyl carbonate is fed into the reactive distillation column at the bottom of the reaction section. They come into contact with sodium methoxide and n-butanol and undergo transesterification to produce methanol and methyl butyl carbonate. The mixture of methanol and unreacted dimethyl carbonate vapor collected from the top of the reactive distillation column is condensed and sent to a membrane separation system to obtain dimethyl carbonate and methanol, respectively. The reaction liquid collected from the bottom of the reactive distillation column includes the reaction product methyl butyl carbonate, the byproduct dibutyl carbonate, and residual dimethyl carbonate and n-butanol in the system. The reaction liquid is then fed into a light-heavy separation column, which employs partitioned-wall distillation technology. The column has two outlets at the top: the first outlet collects dimethyl carbonate and n-butanol, and the second outlet collects methyl butyl carbonate. Dibutyl carbonate is collected from the bottom of the light-heavy separation column.
3. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 2, characterized in that, The dimethyl carbonate and n-butanol extracted from the first outlet are returned to the middle feed inlet of the reaction section of the reactive distillation column; The dibutyl carbonate collected from the bottom of the light-heavy separation tower enters the dibutyl carbonate tower. Dibutyl carbonate product is obtained from the top of the dibutyl carbonate tower, and the bottom of the tower contains material containing sodium methoxide catalyst, which is returned to the upper feed port of the reaction section of the reactive distillation tower.
4. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 3, characterized in that, The dibutyl carbonate product is obtained at the top of the dibutyl carbonate column, and the material containing sodium methoxide catalyst is collected from the bottom of the column and returned to the upper feed inlet of the reaction section of the reactive distillation column.
5. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 1, characterized in that, The molar ratio of dimethyl carbonate to n-butanol is 1.2~3:1; The amount of sodium methoxide used is 0.5% to 5% of the mass of n-butanol.
6. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 1, characterized in that, The internal pressure of the reactive distillation column is atmospheric pressure; The top temperature of the reactive distillation column is 69-73℃; The bottom temperature of the reactive distillation column is 115-140℃; The theoretical plate number of the reaction section of the reactive distillation column is 10-20, and the temperature of the reaction section is 80-90℃; The theoretical plate number of the rectification section of the reactive distillation column is 20-45; The theoretical plate number of the stripping section of the reactive distillation column is 10-25.
7. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 1, characterized in that, The separation membrane in the membrane separation system is an ultrawetting separation membrane; The superwetting separation membrane is a polytetrafluoroethylene / polyacrylonitrile composite membrane.
8. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 1, characterized in that, The light-heavy separation column is a partitioned-wall distillation column; The light and heavy separation tower is equipped with a partition to divide the interior of the distillation tower into a secondary distillation section and a main distillation section, with a common stripping section below the partition. The theoretical plate number of the sub-rectification section is 10-24, the theoretical plate number of the main rectification section is 20-32, and the theoretical plate number of the common stripping section is 8-16. The secondary rectification section and the main rectification section are each equipped with a top condenser. The reflux ratio of the secondary rectification section is 2-6, and the reflux ratio of the main rectification section is 4-8.
9. The method for synthesizing high-purity methyl butyl carbonate using sodium methoxide as a catalyst according to claim 1, characterized in that, The dibutyl carbonate tower is a vacuum tower; The theoretical plate number of the dibutyl carbonate column is 8-16; The reflux ratio of the dibutyl carbonate column is 3-6.