A methyl ethyl carbonate production system and a production method

Abstract

This application provides a methyl ethyl carbonate (MEC) production system and method, relating to the field of MEC production technology. The system includes: a reactive distillation column with a feed inlet, a separation inlet, and a first outlet; a first separation unit connected to the separation inlet to separate a first material; a neutralization evaporation unit connected to the first outlet; a second separation unit with a first circulation inlet, a fourth inlet, and a fourth outlet, the first circulation inlet connected to the reactive distillation column, and the neutralization evaporation unit connected to the fourth inlet; and a MEC column with a fifth inlet, a second circulation inlet, a product outlet, and a by-product outlet, the second circulation inlet connected to the fourth inlet, and the fourth outlet connected to the fifth inlet. The embodiments of this application achieve continuous production of MEC, recover and recycle the reaction raw materials, improve the utilization rate of raw materials, and increase the purity of methyl ethyl carbonate.

Description

Technical Field

[0001] This application relates to the field of methyl ethyl carbonate production technology, and in particular to a methyl ethyl carbonate production system and production method. Background Technology

[0002] Driven by the rapid development of new energy vehicles, energy storage systems and consumer electronics, the market demand for ethyl methyl carbonate (EMC), as one of the solvents in lithium-ion battery electrolytes, continues to grow. The performance of ethyl methyl carbonate affects the energy density, cycle life and safety of batteries.

[0003] In related technologies, the methyl ethyl carbonate (MEC) production system includes a reactor and a distillation column connected in sequence. It employs a batch transesterification method to produce MEC using dimethyl carbonate and ethanol as raw materials. The reaction takes place in a stirred reactor under the catalysis of an alkaline catalyst to generate MEC and methanol as a byproduct. After the reaction is complete, the mixture is transferred to a distillation column for separation and purification to obtain MEC.

[0004] However, traditional intermittent production systems have low raw material conversion rates, cannot carry out continuous production, and have limited capacity. Summary of the Invention

[0005] This application provides a methyl ethyl carbonate (EMC) production system and method, which realizes continuous production of EMC, and recovers and recycles raw materials, thereby improving the utilization rate of raw materials and increasing the purity of EMC.

[0006] To achieve the above objectives, the technical solution of this application is as follows:

[0007] On one hand, this application provides a methyl ethyl carbonate production system, comprising: a reactive distillation column having a feed inlet, a separation inlet, and a first outlet; a first separation unit connected to the separation inlet to separate a first material; a neutralization evaporation unit connected to the first outlet to sequentially neutralize and evaporate the reaction feedstock flowing into the neutralization evaporation unit; a second separation unit having a first circulation inlet, a fourth inlet, and a fourth outlet, the first circulation inlet being connected to the reactive distillation column, and the neutralization evaporation unit being connected to the fourth inlet; and a methyl ethyl carbonate column having a fifth inlet, a second circulation inlet, a product outlet, and a by-product outlet, the second circulation inlet being connected to the fourth inlet, and the fourth outlet being connected to the fifth inlet.

[0008] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment includes a first separation unit comprising a methanol removal tower having a first inlet and a second outlet, the first inlet being connected to a separation port, and a reactive distillation tower having a reflux port, the second outlet being connected to the reflux port.

[0009] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment further includes a pressure swing distillation column connected to the outlet of the methanol removal column in the first separation unit. The pressure swing distillation column has a high-pressure section and a low-pressure section. The operating pressure of the high-pressure section is 0.7 MPa-0.8 MPa, and the operating pressure of the low-pressure section is 0.5 MPa-0.6 MPa.

[0010] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment includes at least one of the first separation unit, the second separation unit, and the methyl ethyl carbonate tower, which is equipped with a reflux pipeline. A reflux pump is installed on the reflux pipeline. One end of the reflux pipeline is connected to the outlet of the first separation unit, the second separation unit, or the methyl ethyl carbonate tower, and the other end of the reflux pipeline is connected to the inlet of the first separation unit, the second separation unit, or the methyl ethyl carbonate tower.

[0011] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment includes a neutralization evaporation unit comprising a neutralization tank, an evaporation tank, a reflux tank, and a condensation transfer pump connected in sequence. The neutralization tank is connected to a first outlet, and the condensation transfer pump is connected to a second separation unit.

[0012] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment has a multi-stage packing layer in the reactive distillation column, a separation port located at the top of the reactive distillation column, a first outlet located at the bottom of the reactive distillation column, a second circulation port located at the top of the methyl ethyl carbonate column, a product outlet located at the upper part of the methyl ethyl carbonate column, and a by-product outlet located at the lower part of the methyl ethyl carbonate column.

[0013] On the other hand, this application also provides a method for producing methyl ethyl carbonate, applied to the methyl ethyl carbonate production system of any of the above embodiments, comprising: feeding a reaction feedstock into a reactive distillation column from a feed inlet for reaction; separating a first material in the reactive distillation column from a separation port to a first separation unit; conveying the reacted feedstock flowing out from the first outlet to a neutralization and evaporation unit for neutralization and evaporation treatment in sequence; sending the evaporated feedstock to a second separation unit, the separated second material returning to the reactive distillation column through a first circulation port, and sending the reacted feedstock separated by the second separation unit into a methyl ethyl carbonate column for distillation, and obtaining a first product (such as methyl ethyl carbonate) from the product outlet.

[0014] In one possible implementation, the method for producing methyl ethyl carbonate provided in this application embodiment involves feeding reactants into a reactive distillation column from the feed inlet to carry out a transesterification reaction by feeding reactants including dimethyl carbonate and ethanol into the reactive distillation column under the action of a catalyst.

[0015] In one possible implementation, the methyl ethyl carbonate production method provided in this application embodiment has an aldehyde and ketone impurity content of ethanol of less than or equal to 0.01 wt%; and / or a water content of ethanol of less than or equal to 0.05 wt%.

[0016] In one possible implementation, the method for producing ethyl methyl carbonate provided in this application embodiment uses an alkali metal alkoxide as the catalyst; the neutralization treatment is carried out using an acid, which is a strong inorganic acid, and the feed molar ratio of dimethyl carbonate to ethanol is 1:1 to 2.5:1.

[0017] This application provides a methyl ethyl carbonate production system and method. The system includes: a reactive distillation column having a feed inlet, a separation inlet, and a first outlet; a first separation unit connected to the separation inlet to separate a first material; a neutralization evaporation unit connected to the first outlet to sequentially neutralize and evaporate the reaction feedstock flowing into the neutralization evaporation unit; a second separation unit having a first circulation inlet, a fourth inlet, and a fourth outlet, the first circulation inlet being connected to the reactive distillation column, and the neutralization evaporation unit being connected to the fourth inlet; and a methyl ethyl carbonate column having a fifth inlet, a second circulation inlet, a product outlet, and a by-product outlet, the second circulation inlet being connected to the fourth inlet, and the fourth outlet being connected to the fifth inlet. This embodiment integrates the reaction and distillation separation processes within a reactive distillation column. A first separation unit removes the first reactant (e.g., methanol) from the column in real time, reducing the methanol concentration and breaking the chemical equilibrium limitations of batch processes. This allows the reaction to continuously proceed towards the formation of methyl ethyl carbonate (MEC), avoiding the low conversion rate problem caused by chemical equilibrium limitations in batch reactions. This facilitates continuous MEC production. A neutralization and evaporation unit sequentially neutralizes and evaporates the reactants after the reaction, removing residual catalyst and some light components to obtain a crude product. A second separation unit returns the reactants (e.g., dimethyl carbonate) to the reactive distillation column through a first circulation port, achieving closed-loop recovery and efficient utilization of the raw materials. The MEC column then uses a second circulation port to circulate and refine the reactants to near-product purity, obtaining high-purity MEC from the product outlet. Therefore, this embodiment achieves continuous production of MEC, real-time recovery and recycling of reactants, and final refining of MEC, improving raw material utilization and MEC purity. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] Figure 1A schematic diagram of a methyl ethyl carbonate production system provided in this application embodiment;

[0020] Figure 2 A schematic diagram of the structure of the first separation unit in a methyl ethyl carbonate production system provided in this application embodiment;

[0021] Figure 3 This is a schematic flow diagram of a method for producing ethyl methyl carbonate, provided as an embodiment of this application.

[0022] Explanation of reference numerals in the attached figures:

[0023] 100 - Reactive distillation column; 101 - Feed inlet; 102 - Separation port; 103 - First outlet; 104 - Reflux port;

[0024] 200 - First separation unit; 201 - First inlet; 202 - Second outlet; 210 - Methanol removal column; 220 - Pressure swing distillation column;

[0025] 300 - Neutralization evaporation unit; 301 - Second inlet; 302 - Third inlet; 303 - Third outlet; 304 - Neutralization outlet; 305 - Evaporation inlet; 306 - Waste liquid outlet; 310 - Neutralization tank; 320 - Evaporation tank; 330 - Reflux tank; 340 - Condensate transfer pump;

[0026] 400 - Second separation unit; 401 - Fourth inlet; 402 - Fourth outlet; 403 - First circulation port;

[0027] 500 - Methyl methyl carbonate tower; 501 - Fifth inlet; 502 - Second circulation outlet; 503 - Product outlet; 504 - By-product outlet;

[0028] 610 - Return line; 620 - Return pump.

[0029] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0030] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent embodiments consistent with this application. Rather, they are merely examples of elements and methods consistent with some aspects of this application as detailed in the appended application.

[0031] It should be noted that in the description of the embodiments of this application, the terms "upper", "lower", "inner", "outer" and other terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description, and are not intended to indicate or imply that the unit or component must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of this application.

[0032] Furthermore, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0034] Driven by the rapid development of new energy vehicles, energy storage systems and consumer electronics, the market demand for ethyl methyl carbonate (EMC), as one of the solvents in lithium-ion battery electrolytes, continues to grow. The performance of ethyl methyl carbonate affects the energy density, cycle life and safety of batteries.

[0035] In related technologies, the production of ethyl methyl carbonate mainly employs a batch transesterification process. Dimethyl carbonate and ethanol are used as raw materials, and the reaction is carried out in a stirred reactor under the catalysis of an alkaline catalyst (such as sodium methoxide) to produce ethyl methyl carbonate and methanol as a byproduct. After the reaction is complete, the mixture is transferred to a distillation column for separation and purification to obtain ethyl methyl carbonate.

[0036] However, traditional intermittent production systems have low feed conversion rates. For example, methanol produced during the reaction is mixed in the system, inhibiting the forward reaction and resulting in low feed conversion rates (such as DMC), making continuous production impossible and limiting capacity.

[0037] In view of the above, this application provides a methyl ethyl carbonate production system and method. The system includes: a reactive distillation column having a feed inlet, a separation inlet, and a first outlet; a first separation unit connected to the separation inlet to separate a first material; a neutralization evaporation unit connected to the first outlet to sequentially neutralize and evaporate the reaction raw materials flowing into the neutralization evaporation unit; a second separation unit having a first circulation inlet, a fourth inlet, and a fourth outlet, the first circulation inlet being connected to the reactive distillation column, and the neutralization evaporation unit being connected to the fourth inlet; and a methyl ethyl carbonate column having a fifth inlet, a second circulation inlet, a product outlet, and a by-product outlet, the second circulation inlet being connected to the fourth inlet, and the fourth outlet being connected to the fifth inlet. This embodiment integrates the reaction and distillation separation processes within a reactive distillation column. A first separation unit removes the first reactant (e.g., methanol) from the column in real time, reducing the methanol concentration and breaking the chemical equilibrium limitations of batch processes. This allows the reaction to continuously proceed towards the formation of methyl ethyl carbonate (MEC), avoiding the low conversion rate problem caused by chemical equilibrium limitations in batch reactions. This facilitates continuous MEC production. A neutralization and evaporation unit sequentially neutralizes and evaporates the reactants after the reaction, removing residual catalyst and some light components to obtain a crude product. A second separation unit returns the reactants (e.g., dimethyl carbonate) to the reactive distillation column through a first circulation port, achieving closed-loop recovery and efficient utilization of the raw materials. The MEC column then uses a second circulation port to circulate and refine the reactants to near-product purity, obtaining high-purity MEC from the product outlet. Therefore, this embodiment achieves continuous production of MEC, real-time recovery and recycling of reactants, and final refining of MEC, improving raw material utilization and MEC purity.

[0038] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0039] This application provides a system for producing ethyl methyl carbonate, such as... Figure 1As shown, it includes: a reactive distillation column 100, which has a feed inlet 101, a separation port 102, and a first outlet 103; a first separation unit 200, which is connected to the separation port 102 to separate a first material; a neutralization evaporation unit 300, which is connected to the first outlet 103 to perform neutralization and evaporation treatments on the reaction raw materials flowing into the neutralization evaporation unit 300 in sequence; a second separation unit 400, which has a first circulation port 403, a fourth inlet 401, and a fourth outlet 402, with the first circulation port 403 connected to the reactive distillation column 100 and the neutralization evaporation unit 300 connected to the fourth inlet 401; and a methyl ethyl carbonate column 500, which has a fifth inlet 501, a second circulation port 502, a product outlet 503, and a by-product outlet 504, with the second circulation port 502 connected to the fourth inlet 401 and the fourth outlet 402 connected to the fifth inlet 501.

[0040] This invention provides a highly efficient and continuous methyl ethyl carbonate (MEC) production system. A reactive distillation column 100 is used to feed the reactants into the reaction. The column is filled with multiple sections of packing or catalytic packing. The feed inlet 101 is located in the reaction section of the packing layer and is used to introduce dimethyl carbonate (DMC), ethanol (EtOH), and the catalyst.

[0041] Separation port 102 is located at the top of reactive distillation column 100 and is used to continuously remove the light component methanol and the azeotrope generated in the reaction, thereby breaking the thermodynamic equilibrium of the transesterification reaction.

[0042] The first outlet 103 is located at the bottom of the reactive distillation column 100, such as the bottom of the reboiler of the reactive distillation column 100, and is used to draw out the crude product rich in methyl ethyl carbonate, reaction raw materials and catalyst.

[0043] The first separation unit 200 is connected to the separation port 102 via a pipeline and is used to receive and process the methanol-containing raw material extracted from the top of the tower.

[0044] The neutralization evaporation unit 300 is connected to the first outlet 103 via a pipe to achieve the deactivation of the catalyst and the initial removal of light components.

[0045] The inlet of the second separation unit 400 is connected to the outlet of the neutralization evaporation unit 300 through a pipe. It is used to further separate light and heavy components. Its first circulation port 403 is connected to the feed port 101 of the reactive distillation column 100 or the reflux port 104 in the upper part of the column through a pipe. It is used to return the recovered raw material (DMC) to the reactive distillation column 100.

[0046] The inlet of the ethyl methyl carbonate column 500 is connected via a pipeline to the heavy component outlet of the second separation unit 400 for final purification of the crude EMC product; its second circulation port 502 is connected via a pipeline to the top reflux line of the second separation unit 400, forming an internal circulation. The by-product outlet 504 is used to output by-products such as diethyl carbonate (DEC), and the product outlet 503 is used to output products such as ethyl methyl carbonate (EMC).

[0047] In some other embodiments, the methyl ethyl carbonate production system may also include a raw material pretreatment unit connected to the feed inlet 101 for dehydrating and removing impurities such as aldehydes and ketones from the DMC and EtOH raw materials.

[0048] The reactants flow continuously under the drive of pumps and differential pressure, forming a closed-loop continuous production process. This solves the technical problems of low capacity, reaction equilibrium limitation, and high raw material consumption in traditional batch processes, and achieves continuous production with high conversion rate and high selectivity.

[0049] Specifically, the first separation unit 200 has a first inlet 201 and a second outlet 202. The first inlet 201 is connected to the separation port 102, and the second outlet 202 is connected to the reflux port 104. The reflux port 104 is provided on the reactive distillation column 100.

[0050] In some embodiments, the first separation unit 200 includes a methanol stripping tower 210, which has a first inlet 201 and a second outlet 202. The first inlet 201 is connected to the separation port 102. The reactive distillation tower 100 has a reflux port 104, and the second outlet 202 is connected to the reflux port 104.

[0051] The neutralization evaporation unit 300 has a second inlet 301, a third inlet 302 and a third outlet 303. The second inlet 301 is connected to the first outlet 103, and the third inlet 302 is used to introduce acidic substances into the neutralization evaporation unit 300 for neutralization reaction.

[0052] The neutralization evaporation unit 300 includes a neutralization unit, such as a neutralization tank 310, which has a second inlet 301, a third inlet 302 and a neutralization outlet 304. The neutralization evaporation unit 300 includes an evaporation unit, with an evaporation inlet 305 connected to the neutralization outlet 304 and a waste liquid outlet 306 for discharging waste liquid.

[0053] The second separation unit 400 has a fourth inlet 401, a fourth outlet 402, and a first circulation port 403. The fourth inlet 401 is connected to the third outlet 303. The first circulation port 403 is used to discharge raw material containing DMC for recycling back to the reactive distillation column 100. The first circulation port 403 can be connected to the feed port 101, the reflux port 104, or another feed port 101 of the reactive distillation column 100. The reactive distillation column 100 has multiple feed ports 101, for example, one feed port 101 for introducing DMC, another feed port 101 for introducing EtOH, another feed port 101 for introducing catalyst, and yet another feed port 101 for introducing DMC circulating out of the first circulation port 403.

[0054] The methyl ethyl carbonate tower 500 has a fifth inlet 501, a second circulation port 502, a product outlet 503, and a by-product outlet 504. The fifth inlet 501 is connected to the fourth outlet 402, the second circulation port 502 is connected to the fourth inlet 401, the product outlet 503 is used to discharge products such as methyl ethyl carbonate, and the by-product outlet 504 is used to discharge DEC.

[0055] In some embodiments, such as Figure 1 As shown, the first separation unit 200 may include a methanol stripping tower 210.

[0056] The second separation unit 400 is also connected to the methyl ethyl carbonate tower 500 through a second circulation port 502. Alternatively, a portion of the side stream extract or top condensate from the second separation unit 400 can be refluxed to the middle of the methyl ethyl carbonate tower 500 to adjust the feed composition and improve product purity.

[0057] In this embodiment, the azeotrope from the top of the reactive distillation column 100 (such as methanol, with trace amounts of DMC and EtOH) first enters the methanol removal column 210. This methanol removal column 210 is a distillation column operating at atmospheric or slightly pressurized pressure. By controlling a suitable reflux ratio, the top of the column yields a first feedstock rich in methanol, while the bottom contains the reaction feedstock containing residual DMC and EtOH. After separation, the reaction feedstock containing DMC and EtOH enters the reactive distillation column 100 through reflux port 104.

[0058] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment, combined with Figure 1 and Figure 2 The first separation unit 200 also includes a pressure swing distillation column 220 connected to the outlet of the methanol removal column 210. The pressure swing distillation column 220 has a high-pressure section and a low-pressure section. The operating pressure of the high-pressure section is 0.7MPa-0.8MPa, and the operating pressure of the low-pressure section is 0.5MPa-0.6MPa.

[0059] In the high-pressure section (e.g., 0.7 MPa-0.8 MPa), the relative volatility of methanol and DMC / EtOH changes, which is beneficial for obtaining a DMC / EtOH-rich reaction feedstock in the bottom of the column. This feedstock is then throttled and depressurized before entering the low-pressure section (0.5 MPa-0.6 MPa). At the lower pressure, residual methanol is more readily volatilized from the mixture and collected from the top of the low-pressure section. The resulting methanol is returned to the front end of the methanol removal column 210 for further processing or treated as a byproduct, while the bottom of the column yields a higher-purity DMC / EtOH mixture for recycling.

[0060] In some embodiments, the high-pressure section and the low-pressure section can be two independent towers connected by pipes and pumps, or they can be a dual-pressure zone inside a tower body achieved by a partition.

[0061] The bottom liquid of the methanol stripping column 210 is then pumped into the pressure swing distillation column 220. The pressure swing distillation column 220 employs a high-pressure section and a low-pressure section, and by changing the operating pressure, it disrupts the azeotropic composition of methanol and DMC or methanol and EtOH, achieving efficient separation of DMC, EtOH, and residual methanol. The separated high-purity DMC and / or EtOH are collected through pipelines from specific locations in the pressure swing distillation column 220 (such as the bottom of the high-pressure section or the top of the low-pressure section) and circulated back to the corresponding feed inlet 101 of the reactive distillation column 100 via the first recirculation port 403 or an independent reflux line 610.

[0062] This application recovers valuable raw materials from azeotropes that were previously difficult to process, reducing the consumption of fresh raw materials and solving the problem of high raw material loss. The reaction raw materials flow sequentially through two towers, and component separation and directional circulation are achieved under pressure changes.

[0063] The embodiments of this application can separate substances based on the azeotropic properties of a specific system, solving the problem that traditional single pressure distillation cannot effectively separate azeotropes and improving recovery efficiency.

[0064] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment, such as... Figure 1 As shown, at least one of the first separation unit 200, the second separation unit 400, and the methyl ethyl carbonate tower 500 is provided with a reflux pipeline 610. A reflux pump 620 is provided on the reflux pipeline 610. One end of the reflux pipeline 610 is connected to the outlet of the first separation unit 200, the second separation unit 400, or the methyl ethyl carbonate tower 500, and the other end of the reflux pipeline 610 is connected to the inlet of the first separation unit 200, the second separation unit 400, or the methyl ethyl carbonate tower 500.

[0065] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment includes a neutralization evaporation unit 300 comprising a neutralization tank 310, an evaporation tank 320, a reflux tank 330, and a condensation transfer pump 340 connected in sequence. The neutralization tank 310 is connected to a first outlet 103, and the condensation transfer pump 340 is connected to a second separation unit 400.

[0066] The crude EMC reaction feedstock containing alkali metal alkoxide catalyst from the bottom of reactive distillation column 100 first enters neutralization tank 310.

[0067] In some embodiments, an acidic neutralizing agent, such as sulfuric acid with a concentration of 96% to 98%, is added to the neutralization tank 310 through a separate pipeline from the third inlet 302. The neutralizing agent is thoroughly mixed with the reactants by stirring, causing a neutralization reaction that deactivates the catalyst and generates salts (such as sodium sulfate).

[0068] The neutralized reaction materials flow out from the bottom of the neutralization tank 310 and enter the evaporation tank 320.

[0069] The evaporator 320 is equipped with a heating coil, which indirectly heats the low-boiling-point components (such as residual methanol and ethanol) and some water in the reaction raw materials to evaporate and vaporize. The vapor phase enters the condensation system, while the liquid phase (mainly EMC, DMC and high-boiling substances) enters the reflux tank 330 for temporary storage.

[0070] The reflux tank 330 serves as a buffer and gas-liquid separator. Finally, the reaction raw materials are pumped into the second separation unit 400 by the condenser transfer pump 340.

[0071] By appropriately separating the neutralization reaction from the evaporation operation in physical space, safe and efficient continuous processing is achieved, solving the problems of product decomposition and subsequent equipment corrosion caused by catalyst residue. The condensate transfer pump 340 is a coarse EMC condensate pump to avoid thermal decomposition of EMC.

[0072] In one possible implementation, the methyl ethyl carbonate production system provided in this application embodiment has a multi-stage packing layer in the reactive distillation column 100, a separation port 102 located at the top of the reactive distillation column 100, a first outlet 103 located at the bottom of the reactive distillation column 100, a second circulation port 502 located at the top of the methyl ethyl carbonate column 500, a product outlet 503 located at the upper part of the methyl ethyl carbonate column 500, and a by-product outlet 504 located at the lower part of the methyl ethyl carbonate column 500.

[0073] On the other hand, this application also provides a method for producing methyl ethyl carbonate, combined with Figures 1 to 3 include:

[0074] S100, reactants are introduced into the reactive distillation column 100 through the feed inlet 101 for reaction.

[0075] S110. The reaction feedstock containing dimethyl carbonate and ethanol is fed into the reactive distillation column 100 to carry out the transesterification reaction under the action of a catalyst.

[0076] DMC, EtOH, and catalyst are continuously and stably fed into the reactive distillation column 100 from different feed inlets 101.

[0077] The aldehyde and ketone impurities in ethanol are less than or equal to 0.01 wt%; and / or the water content in ethanol is less than or equal to 0.05 wt%, in order to reduce impurity contamination, avoid catalyst deactivation, and thus limit the water content of ethanol.

[0078] S200, the first material in the reactive distillation column 100 is separated from the separation port 102 to the first separation unit 200.

[0079] Inside the column, the transesterification reaction and product separation occur simultaneously. The first material generated by the reaction (such as methanol) is continuously removed from the top of the column, thereby shifting the reaction equilibrium to the right and making the conversion rate of DMC higher than that of a batch reactor.

[0080] S300, the reaction raw materials flowing out from the first outlet 103 are transported to the neutralization and evaporation unit 300 for neutralization and evaporation treatment in sequence.

[0081] S310: After the reaction is discharged from the reactor, the raw materials immediately enter the neutralization and evaporation unit 300, where they are neutralized by adding acid and light components are removed by evaporation.

[0082] The catalyst is an alkali metal alkoxide; neutralization is carried out using an acid, which is a strong inorganic acid, with a feed molar ratio of dimethyl carbonate to ethanol of 1:1 to 2.5:1.

[0083] S400: The evaporated reaction raw material is sent to the second separation unit 400. The separated second material is returned to the reaction distillation column 100 through the first circulation port 403. The reaction raw material separated by the second separation unit 400 is sent to the methyl ethyl carbonate column 500 for distillation. The first product (such as methyl ethyl carbonate) is obtained from the product outlet 503.

[0084] After evaporation, the reaction feedstock enters the second separation unit 400 (e.g., a light component removal tower), where light components such as DMC are separated and returned to the reactive distillation tower 100 through the first circulation port 403 to participate in the reaction again, thus improving the feedstock utilization rate. The reaction liquid rich in EMC enters the methyl ethyl carbonate tower 500, where high-purity first product (e.g., methyl ethyl carbonate) is obtained through distillation, and byproducts such as DEC are separated.

[0085] This method utilizes reactive distillation to break the thermodynamic equilibrium and achieves efficient utilization of the reaction raw materials through multi-stage separation and recycling, solving the problems of low conversion rate, limited capacity, and large raw material loss in the production of methyl ethyl carbonate in related technologies.

[0086] For example, the reaction raw materials are dimethyl carbonate (DMC) with a purity of not less than 99.8% and ethanol (EtOH) with a purity of not less than 99.7%, wherein the aldehyde and ketone impurity content of EtOH is not higher than 0.008 wt% and the moisture content is not higher than 0.04 wt%; a sodium methoxide-methanol solution (SM catalyst) with a concentration of 28 wt% is used as the catalyst, and sulfuric acid with a concentration of 98 wt% is used as the neutralizing agent.

[0087] It is understood that this application selects high-purity reaction raw materials and controls their quality, such as aldehyde and ketone impurities in EtOH ≤0.01wt% and moisture in EtOH ≤0.05wt%, thereby reducing the introduction of impurities at the source. For example, a 22wt% sodium methoxide methanol solution is used as the catalyst, which has high catalytic activity and is easily neutralized and deactivated by sulfuric acid; 98wt% sulfuric acid is used as the neutralizing agent to control the neutralization reaction and avoid the impact of excessive acid or alkali on subsequent processes. In some embodiments, for example, a 28wt% sodium methoxide methanol solution can also be used as the catalyst.

[0088] During the reactive distillation process, DMC and EtOH are continuously fed into reactive distillation column 100 at a mass flow rate of approximately 1.96:1, while SM catalyst is added simultaneously. The theoretical plate number of reactive distillation column 100 is controlled at 25, the operating reflux ratio is 3, the temperature of the reaction section inside the column is controlled at 100℃, and the pressure inside the column is controlled at 0.2MPa. The methanol produced by the reaction is continuously collected from the top of the column.

[0089] During the neutralization and evaporation process: the reaction feedstock output from the bottom of the reactive distillation column 100 is sent to the neutralization tank 310, and 98wt% sulfuric acid is added for neutralization. After neutralization, the reaction feedstock is evaporated to remove light components.

[0090] During the separation and recycling of light components, the evaporated reaction raw materials are sent to the second separation unit 400, and the separated light components are returned to the reactive distillation column 100 through the first circulation port 403; the bottom liquid of the column rich in ethyl methyl carbonate (EMC) is sent to the ethyl methyl carbonate column 500.

[0091] During the product refining process, distillation is carried out in methyl ethyl carbonate column 500 at 120°C and 0.15 MPa. EMC products with a purity of not less than 99.92% are collected from the product outlet of the column.

[0092] In the process of methanol recovery and by-product treatment, methanol is recovered from the first separation unit 200 and purified by pressure swing distillation to obtain methanol with a purity of not less than 99.6%; the sodium sulfate by-product generated by neutralization is obtained as a solid after evaporation and centrifugation.

[0093] Furthermore, this application also maintains the total moisture content in the circulating reaction feedstock below 0.08 wt% through system dehydration control. For example, this application also maintains the total moisture content in the circulating reaction feedstock below 0.08 wt% through a feedstock pretreatment unit (such as a molecular sieve dehydration tower) located at the feed inlet of the reactive distillation column 100 and through control of evaporation conditions in the neutralization evaporation unit 300.

[0094] Through the above methods, continuous production of EMC is achieved, the DMC unit consumption loss rate is less than 3.2%, and the EMC product qualification rate reaches 100%.

[0095] This application avoids side reactions caused by excessive catalyst by controlling the feed mass ratio of DMC to EtOH and the amount of SM catalyst. During the reaction, methanol is removed from the top of the column in real time, breaking the reaction equilibrium and increasing the EMC yield to over 95%, which is 10%-15% higher than the traditional batch method.

[0096] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only.

[0097] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A system for producing methyl ethyl carbonate, characterized in that, include: A reactive distillation column (100) having a feed inlet (101), a separation inlet (102) and a first outlet (103); A first separation unit (200) is connected to the separation port (102) to separate a first material; Neutralization evaporation unit (300), which is connected to the first outlet (103) to perform neutralization and evaporation treatment on the reaction raw materials flowing into the neutralization evaporation unit (300) in sequence; The second separation unit (400) has a first circulation port (403), a fourth inlet (401) and a fourth outlet (402). The first circulation port (403) is connected to the reactive distillation column (100), and the neutralization evaporation unit (300) is connected to the fourth inlet (401). ethyl methyl carbonate tower (500) has a fifth inlet (501), a second circulation port (502), a product outlet (503) and a by-product outlet (504), the second circulation port (502) being connected to the fourth inlet (401) and the fourth outlet (402) being connected to the fifth inlet (501).

2. The methyl ethyl carbonate production system according to claim 1, characterized in that, The first separation unit (200) includes a methanol stripping tower (210), which has a first inlet (201) and a second outlet (202). The first inlet (201) is connected to the separation port (102), and the reactive distillation tower (100) has a reflux port (104). The second outlet (202) is connected to the reflux port (104).

3. The methyl ethyl carbonate production system according to claim 2, characterized in that, The first separation unit (200) further includes a pressure swing distillation column (220) connected to the outlet of the methanol removal column (210). The pressure swing distillation column (220) has a high-pressure section and a low-pressure section. The operating pressure of the high-pressure section is 0.7MPa-0.8MPa, and the operating pressure of the low-pressure section is 0.5MPa-0.6MPa.

4. The methyl ethyl carbonate production system according to any one of claims 1-3, characterized in that, At least one of the first separation unit (200), the second separation unit (400), and the methyl ethyl carbonate tower (500) is provided with a reflux pipeline (610), and a reflux pump (620) is provided on the reflux pipeline (610). One end of the reflux pipeline (610) is connected to the outlet of the first separation unit (200), the second separation unit (400), or the methyl ethyl carbonate tower (500), and the other end of the reflux pipeline (610) is connected to the inlet of the first separation unit (200), the second separation unit (400), or the methyl ethyl carbonate tower (500).

5. The methyl ethyl carbonate production system according to any one of claims 1-3, characterized in that, The neutralization evaporation unit (300) includes a neutralization tank (310), an evaporation tank (320), a reflux tank (330), and a condensation transfer pump (340) connected in sequence. The neutralization tank (310) is connected to the first outlet (103), and the condensation transfer pump (340) is connected to the second separation unit (400).

6. The methyl ethyl carbonate production system according to any one of claims 1-3, characterized in that, The reactive distillation column (100) is provided with multiple packing layers. The separation port (102) is located at the top of the reactive distillation column (100), the first outlet (103) is located at the bottom of the reactive distillation column (100), the second circulation port (502) is located at the top of the methyl ethyl carbonate column (500), the product outlet (503) is located at the upper part of the methyl ethyl carbonate column (500), and the by-product outlet (504) is located at the lower part of the methyl ethyl carbonate column (500).

7. A method for producing methyl ethyl carbonate, applied to the methyl ethyl carbonate production system according to any one of claims 1-6, characterized in that, include: The reactant is introduced into the reactive distillation column (100) through the feed inlet (101) for reaction; The first material in the reactive distillation column (100) is separated from the separation port (102) to the first separation unit (200); The reaction raw materials flowing out from the first outlet (103) are transported to the neutralization and evaporation unit (300) for neutralization and evaporation treatment in sequence; The evaporated reaction raw material is sent to the second separation unit (400), and the separated second material is returned to the reaction distillation column (100) through the first circulation port (403). The reaction raw material separated by the second separation unit (400) is sent to the methyl ethyl carbonate column (500) for distillation, and methyl ethyl carbonate is obtained from the product outlet (503).

8. The method for producing methyl ethyl carbonate according to claim 7, characterized in that, The process of introducing reactants into the reactive distillation column (100) from the feed inlet (101) for reaction includes: The reaction feedstock, including dimethyl carbonate and ethanol, is fed into a reactive distillation column (100) to carry out an ester exchange reaction under the action of a catalyst.

9. The method for producing methyl ethyl carbonate according to claim 8, characterized in that, The ethanol has an aldehyde and ketone impurity content of less than or equal to 0.01 wt%; and / or, the ethanol has a water content of less than or equal to 0.05 wt%.

10. The method for producing methyl ethyl carbonate according to claim 9, characterized in that, The catalyst is an alkali metal alkoxide; the neutralization treatment is carried out using acid; and the feed molar ratio of dimethyl carbonate to ethanol is 1:1 to 2.5:1.

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