Continuous production system for diethyl maleate
By combining reactive distillation columns, benzene-water separators, vacuum distillation columns, benzene removal columns, and ethanol distillation columns, the problems of low purity and raw material waste in the diethyl maleate production unit were solved, achieving continuous production with high purity and high efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI DAOZUAN MASCH EQUIP CO LTD
- Filing Date
- 2025-04-27
- Publication Date
- 2026-05-12
AI Technical Summary
In existing diethyl maleate production facilities, the purity of the distillation column products is low, and the wastewater is not recycled, resulting in waste of raw materials.
A combined system of reactive distillation column, benzene-water separator, vacuum distillation column, benzene removal column and ethanol distillation column is adopted. Through azeotropic distillation, vacuum distillation and atmospheric pressure dual-tower distillation technology, the components are separated and recycled, improving product purity and recycling benzene and ethanol.
The purity of diethyl maleate was increased to over 99.9 wt%, enhancing the continuity of production and improving the utilization rate of raw materials.
Smart Images
Figure CN224220756U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of diethyl maleate production technology, and in particular to a continuous production system for diethyl maleate. Background Technology
[0002] Diethyl maleate has the chemical formula C8H 12 O4 is a colorless, transparent, oily liquid that can be used as a monomer for polymeric compounds and as an intermediate in pesticide production. Diethyl maleate is synthesized from maleic anhydride and ethanol via esterification. Chinese patent application CN114570052A, published on June 3, 2022, discloses a method and apparatus for the continuous production of diethyl maleate, comprising: a maleic anhydride solvent tank, the top of which is connected to a material inlet, and the bottom of which is connected to a transfer pump A via a pipe; a distillation column body, one side of which is connected to the transfer pump A via a pipe, and four sets of feed inlets are provided outside the distillation column body. The device has the following defects: (1) The product of the distillation column is not purified, and the resulting diethyl maleate has low purity (98.8% and 99.1%); (2) The condensate water layer wastewater in the condensate layering column is discharged from the wastewater outlet to the environmental protection station, and after harmless treatment, it is sent to the next level environmental protection station for discharge. The wastewater is not recycled, resulting in the waste of raw materials (benzene and ethanol in the wastewater). Utility Model Content
[0003] This invention aims to solve the aforementioned problems existing in the current diethyl maleate production equipment, and provides a continuous production system for diethyl maleate that is stable in operation, has good production continuity, can improve the purity of diethyl maleate and the utilization rate of raw materials, and is suitable for large-scale production.
[0004] To achieve the above objectives, this utility model adopts the following technical solution: a continuous production system for diethyl maleate, comprising a reactive distillation column, a benzene-water separator, a vacuum distillation column, a benzene removal column, and an ethanol distillation column; the upper inlet of the reactive distillation column is connected to a side feed pipeline, the top outlet of the reactive distillation column is connected to a first condenser, the outlet of the first condenser is connected to the inlet of the benzene-water separator via a pipeline, and the bottom outlet of the reactive distillation column is connected to the middle inlet of the vacuum distillation column via a pipeline; the benzene phase outlet of the benzene-water separator is connected to the top reflux port of the reactive distillation column via a pipeline, and the aqueous phase outlet of the benzene-water separator is connected to the middle inlet of the benzene removal column via a pipeline. The vacuum distillation column has the following connections: the light component outlet at the top is connected to a second condenser, the outlet of the second condenser is connected to a light component outlet pipeline, the bottom outlet of the vacuum distillation column is connected to a heavy component outlet pipeline, and a side outlet pipeline is connected to the middle section of the vacuum distillation column; the benzene removal column has the top outlet connected to a third condenser, the outlet of the third condenser is connected to the inlet of a benzene-water separator via a pipeline, the bottom outlet of the benzene removal column is connected to the inlet of the middle section of the ethanol distillation column via a pipeline; the ethanol distillation column has the top outlet connected to a fourth condenser, the outlet of the fourth condenser is connected to an ethanol outlet pipeline, and the top outlet of the ethanol distillation column is connected to a wastewater pipeline. This invention uses maleic anhydride and ethanol as raw materials, and carries out an esterification reaction in a reactive distillation column. Simultaneously, the product diethyl maleate and water are separated. During the reaction, azeotropic distillation is performed using benzene as an azeotropic agent, carrying water and a small amount of ethanol out of the reaction system. The azeotropic agent benzene is separated in a benzene-water separator and then refluxed back into the column. A vacuum distillation column (vacuum degree 2-2.1 kPa) is used to purify the bottom material in the reactive distillation column, and the final product, diethyl maleate, has a purity of [missing information]. The purity reaches over 99.9 wt%, indicating high product purity. This invention employs atmospheric pressure dual-tower distillation technology to process the top material of a reactive distillation column. The benzene removal column is used to remove the reboiling agent benzene from the aqueous phase material, and then the reboiling agent benzene is recycled to the benzene-water separator for reuse. The top material of the benzene removal column consists of azeotropic agent benzene and ethanol, while the bottom material of the benzene removal column consists of ethanol and water. The materials are then transported to the ethanol distillation column for the separation of ethanol and water. The ethanol separated from the top of the ethanol distillation column is transported back to the reactive distillation column as a raw material reactant.
[0005] Preferably, a side-stream buffer tank is also included. The inlet of the side-stream buffer tank is connected to the outlet in the middle of the reactive distillation column via a pipeline, and the outlet of the side-stream buffer tank is connected to the inlet at the top and bottom of the reactive distillation column via pipelines. The side-stream buffer tank can increase the liquid flow rate in the column, increase the reaction volume, and enhance the reaction temperature.
[0006] Preferably, the outlet of the second condenser is also connected to the top reflux port of the vacuum distillation column via a pipeline.
[0007] Preferably, the outlet of the third condenser is also connected to the top reflux port of the benzene removal tower via a pipeline.
[0008] Preferably, the outlet of the fourth condenser is also connected to the top reflux port of the ethanol distillation column via a pipeline.
[0009] Preferably, after the light components in the vacuum distillation column are cooled by the second condenser, part of them are discharged and the other part is returned to the top of the vacuum distillation column.
[0010] Preferably, the light component consisting of benzene and ethanol collected from the top of the benzene removal tower is cooled by a third condenser, and a portion is sent to a benzene-water separator for reuse, while the other portion is returned to the top of the vacuum distillation tower.
[0011] Preferably, the heavy component consisting of water and ethanol obtained from the bottom of the benzene removal tower is transported to the ethanol distillation tower. After separation in the ethanol distillation tower, ethanol is collected from the top of the ethanol distillation tower. Part of the ethanol is fed into the reactive distillation tower as a raw material, and the other part of the ethanol is refluxed to the top of the vacuum distillation tower.
[0012] Preferably, the reactive distillation column is equipped with at least four layers of packing, the vacuum distillation column with at least three layers of packing, and both the benzene removal column and the ethanol distillation column with at least three layers of packing. This design ensures efficient distillation, and a redistributor is installed above each layer of packing.
[0013] Therefore, this utility model has the following beneficial effects: it contains a vacuum distillation column, a benzene removal column, and an ethanol distillation column. The vacuum distillation column is used to purify the bottom material of the reaction distillation column, thereby improving the product purity. The benzene removal column is used to remove the reboiling agent benzene from the aqueous phase material in the benzene-water separator, and then the reboiling agent benzene is recycled back to the benzene-water separator for reuse. The ethanol distillation column is used to separate ethanol and water from the bottom material of the benzene removal column, and to recover and reuse ethanol, thereby effectively improving the utilization rate of raw materials. Attached Figure Description
[0014] Figure 1 This is a connection diagram of this utility model.
[0015] In the diagram: 1. Reactive distillation column; 2. Benzene-water separator; 3. Vacuum distillation column; 4. Benzene removal column; 5. Ethanol distillation column; 6. Side feed line; 7. First condenser; 8. Second condenser; 9. Light component discharge line; 10. Heavy component discharge line; 11. Side feed line; 12. Third condenser; 13. Fourth condenser; 14. Ethanol discharge line; 15. Wastewater line; 16. Side buffer tank. Detailed Implementation
[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0017] like Figure 1 The illustrated continuous production system for diethyl maleate includes a reactive distillation column 1, a benzene-water separator 2, a vacuum distillation column 3, a benzene removal column 4, an ethanol distillation column 5, and a side-stream buffer tank 16. The upper inlet of the reactive distillation column is connected to a side-stream feed line 6, and the top outlet of the reactive distillation column is connected to a first condenser 7. The outlet of the first condenser is connected to the inlet of the benzene-water separator via a pipeline, and the bottom outlet of the reactive distillation column is connected to the vacuum distillation column via a pipeline. The feed inlet of the distillation column is connected to the middle section of the column body. The feed inlet of the side-stream buffer tank is connected to the discharge outlet of the middle section of the reactive distillation column via pipelines. The discharge outlet of the side-stream buffer tank is connected to the feed inlets at the top and bottom of the reactive distillation column via pipelines. The benzene phase outlet of the benzene-water separator is connected to the reflux port at the top of the reactive distillation column via pipelines. The aqueous phase outlet of the benzene-water separator is connected to the feed inlet at the middle section of the benzene removal column via pipelines. The top of the vacuum distillation column... The light component outlet is connected to a second condenser 8, and the outlet of the second condenser is connected to a light component outlet pipeline 9. The outlet of the second condenser is also connected to the top reflux port of the vacuum distillation column via a pipeline. The bottom outlet of the vacuum distillation column is connected to a heavy component outlet pipeline 10, and a side outlet pipeline 11 is connected to the middle of the vacuum distillation column. The top outlet of the benzene removal column is connected to a third condenser 12, and the outlet of the third condenser is connected to the inlet of the benzene-water separator via a pipeline. The feed inlet is connected to the third condenser, and the outlet of the third condenser is also connected to the top reflux port of the benzene removal tower via a pipeline. The bottom outlet of the benzene removal tower is connected to the feed inlet in the middle of the ethanol distillation tower via a pipeline. The top outlet of the ethanol distillation tower is connected to the fourth condenser 13, and the outlet of the fourth condenser is connected to the ethanol discharge pipe 14. The outlet of the fourth condenser is also connected to the top reflux port of the ethanol distillation tower via a pipeline. The top outlet of the ethanol distillation tower is connected to the wastewater pipe 15.
[0018] The operation process of this utility model is as follows: Ethanol, maleic anhydride, and catalyst are fed to the reactive distillation column via a side feed pipeline. Benzene, the azeotropic agent, is fed from the benzene-water separator through the reflux port at the top of the reactive distillation column. After the reaction in the reactive distillation column, a light component consisting of benzene, ethanol, and water is collected from the top of the column. After cooling in the first condenser, it enters the benzene-water separator for oil-water separation. The benzene phase is refluxed back to the top of the reactive distillation column through the benzene phase outlet of the benzene-water separator, while the aqueous phase enters the benzene removal column through the aqueous phase outlet of the benzene-water separator. The reaction liquid at the bottom of the reactive distillation column is transported via pipeline to the vacuum distillation column for purification through the bottom outlet. The light component in the vacuum distillation column is cooled by the second condenser... Part of the product is discharged, and the other part is returned to the top of the vacuum distillation column. The heavy components in the vacuum distillation column are discharged through the heavy components discharge pipeline, and the product diethyl maleate is discharged from the side discharge pipeline. After the aqueous phase is separated by the benzene stripping column, the light component composed of benzene and ethanol collected from the top of the benzene stripping column is cooled by the third condenser. Part of it is sent to the benzene-water separator for reuse, and the other part is returned to the top of the benzene stripping column. The heavy component composed of water and ethanol obtained from the bottom of the benzene stripping column is sent to the ethanol distillation column. After separation in the ethanol distillation column, ethanol (94 wt%) is collected from the top of the ethanol distillation column. Part of the ethanol is fed into the reactive distillation column as a raw material, and the other part of the ethanol is returned to the top of the vacuum distillation column. Water is discharged from the bottom of the ethanol distillation column.
[0019] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.
Claims
1. A continuous production system for diethyl maleate, characterized in that, It includes a reactive distillation column (1), a benzene-water separator (2), a vacuum distillation column (3), a benzene removal column (4), and an ethanol distillation column (5); The upper feed inlet of the reactive distillation column is connected to a side feed pipeline (6), the top outlet of the reactive distillation column is connected to a first condenser (7), the outlet of the first condenser is connected to the feed inlet of the benzene-water separator through a pipeline, and the bottom outlet of the reactive distillation column is connected to the feed inlet in the middle of the vacuum distillation column through a pipeline. The benzene phase outlet of the benzene-water separator is connected to the top reflux port of the reactive distillation column via a pipeline, and the aqueous phase outlet of the benzene-water separator is connected to the feed inlet in the middle of the benzene removal column via a pipeline. The light component outlet at the top of the vacuum distillation column is connected to a second condenser (8), the outlet of the second condenser is connected to a light component outlet pipeline (9), the bottom outlet of the vacuum distillation column is connected to a heavy component outlet pipeline (10), and the middle part of the vacuum distillation column is connected to a side outlet pipeline (11). The top outlet of the benzene removal tower is connected to a third condenser (12), the outlet of the third condenser is connected to the inlet of the benzene-water separator through a pipeline, and the bottom outlet of the benzene removal tower is connected to the inlet of the middle part of the ethanol distillation tower through a pipeline. The top outlet of the ethanol distillation column is connected to a fourth condenser (13), the outlet of the fourth condenser is connected to an ethanol discharge pipe (14), and the top outlet of the ethanol distillation column is connected to a wastewater pipe (15).
2. The continuous production system for diethyl maleate according to claim 1, characterized in that, It also includes a side-stream buffer tank (16), the inlet of which is connected to the outlet in the middle of the reactive distillation column via a pipeline, and the outlet of which is connected to the inlet at the top and the inlet at the bottom of the reactive distillation column via pipelines.
3. The continuous production system for diethyl maleate according to claim 1, characterized in that, The outlet of the second condenser is also connected to the top reflux port of the vacuum distillation column via a pipeline.
4. The continuous production system for diethyl maleate according to claim 1, characterized in that, The outlet of the third condenser is also connected to the top reflux port of the benzene removal tower via a pipeline.
5. The continuous production system for diethyl maleate according to claim 1, characterized in that, The outlet of the fourth condenser is also connected to the top reflux port of the ethanol distillation column via a pipeline.
6. The continuous production system for diethyl maleate according to claim 1, characterized in that, The reactive distillation column is provided with at least four layers of packing, the vacuum distillation column is provided with at least three layers of packing, and both the benzene removal column and the ethanol distillation column are provided with at least three layers of packing.