Continuous production system and continuous production method of diethyl maleate

Abstract

The invention discloses a continuous production system for diethyl maleate. The continuous production system comprises a reactive distillation tower, a benzene-water separation tank, a vacuum distillation tower, a benzene removal tower and an ethanol distillation tower. The device comprises the vacuum rectifying tower, the debenzolization tower and the ethanol rectifying tower, and the vacuum rectifying tower is used for purifying tower kettle materials in the reaction rectifying tower, so that the product purity is improved; the debenzolization tower is used for removing a reboiling agent benzene in a water-phase material in the benzene-water separation tank, then the reboiling agent benzene is circulated to the benzene-water separation tank for reuse, the ethanol rectifying tower is used for separating ethanol and water from a material in a tower kettle of the debenzolization tower, and the ethanol is recycled, so that the utilization rate of raw materials is effectively improved. The invention further discloses a continuous production method of the diethyl maleate, a vacuum rectification technology and a normal-pressure double-tower rectification technology are adopted, the purity of the obtained diethyl maleate product can reach 99.9 wt% or above, the product purity is high, reboiling agents benzene and ethyl alcohol can be effectively recycled, and the utilization rate of raw materials is effectively increased.

Description

Technical Field

[0001] The present invention relates to the technical field of diethyl maleate production, and in particular to a continuous production system and a continuous production method for diethyl maleate. Background Art

[0002] The chemical formula of diethyl maleate is C 8 H 12 O 4 , which is a colorless and transparent oily liquid and can be used as a monomer of high molecular compounds and an intermediate of pesticides. Diethyl maleate is synthesized by an esterification reaction using maleic anhydride and ethanol as raw materials. Chinese Patent with application publication number CN114570052A and application publication date June 3, 2022 discloses a method and a device for continuously producing diethyl maleate, including: a maleic anhydride dissolving kettle, the top of the maleic anhydride dissolving kettle is connected with a material inlet of the dissolving kettle, and a pipeline is arranged at the bottom of the maleic anhydride dissolving kettle and connected to a delivery pump A; a rectifying tower body, one side of the rectifying tower body is connected and communicated with the delivery pump A through a pipeline, and four groups of feed inlets are arranged outside the rectifying tower body. This device has the following defects: (1) The product of the rectifying tower is not purified, and the purity of the obtained diethyl maleate is low (98.8% and 99.1%); (2) The waste water in the water layer of the condensate in the condensate separation tower is discharged from the waste water outlet and sent to the environmental protection station, and after being harmlessly treated, it is sent to the next-level environmental protection station for external discharge, and the waste water is not recycled, resulting in waste of raw materials (benzene and ethanol in the waste water). Summary of the Invention

[0003] The present invention is to solve the above problems existing in the prior art diethyl maleate production device, and provides a continuous production system for diethyl maleate with stable operation, good production continuity, capable of improving the purity of diethyl maleate and the utilization rate of raw materials, and suitable for large-scale production.

[0004] The present invention also provides a continuous production method for diethyl maleate, which can produce diethyl maleate with high purity and effectively improve the utilization rate of raw materials.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A continuous production system for diethyl maleate, comprising a reactive distillation column, a benzene-water separation tank, a vacuum distillation column, a benzene removal column, and an ethanol distillation column; the upper feed port of the column body of the reactive distillation column is connected to a side-line feed pipeline, the top discharge port of the reactive distillation column is connected to a first condenser, the discharge port of the first condenser is connected to the feed port of the benzene-water separation tank through a pipeline, and the bottom discharge port of the reactive distillation column is connected to the middle feed port of the column body of the vacuum distillation column through a pipeline; the benzene-phase outlet on the benzene-water separation tank is connected to the top reflux port of the reactive distillation column through a pipeline, and the water-phase outlet on the benzene-water separation tank is connected to the middle feed port of the column body of the benzene removal column through a pipeline; the top light-component discharge port of the vacuum distillation column is connected to a second condenser, the discharge port of the second condenser is connected to a light-component discharge pipeline, the bottom discharge port of the vacuum distillation column is connected to a heavy-component discharge pipeline, and the middle part of the column body of the vacuum distillation column is connected to a side-line discharge pipeline; the top discharge port of the benzene removal column is connected to a third condenser, the discharge port of the third condenser is connected to the feed port of the benzene-water separation tank through a pipeline, and the bottom discharge port of the benzene removal column is connected to the middle feed port of the column body of the ethanol distillation column through a pipeline; the top discharge port of the ethanol distillation column is connected to a fourth condenser, the discharge port of the fourth condenser is connected to an ethanol discharge pipe, and the top discharge port of the ethanol distillation column is connected to a waste water pipe. The present invention uses maleic anhydride and ethanol as raw materials, and performs an esterification reaction in the reactive distillation column. At the same time, the product diethyl maleate and water are separated. During the reaction, azeotropic distillation is carried out by introducing an azeotropic agent benzene to carry water and a small amount of ethanol out of the reaction system. The azeotropic agent benzene is separated by the benzene-water separation tank and then refluxed back into the column. The reactive distillation column is preferably provided with at least four layers of packing; the vacuum distillation column uses vacuum distillation technology (the vacuum degree in the column is 2-2.1 kPa) to purify the bottom material in the reactive distillation column. The finally obtained product diethyl maleate has a purity of more than 99.9 wt%, and the product has a high purity. The vacuum distillation column is preferably provided with at least three layers of packing; the present invention uses atmospheric pressure two-column distillation technology to treat the top material of the reactive distillation column. Among them, the benzene removal column is used to remove the reboiling agent benzene in the water-phase material, and then recycle the reboiling agent benzene to the benzene-water separation tank for reuse. The top material of the benzene removal column consists of the azeotropic agent benzene and ethanol, and the bottom material of the benzene removal column consists of ethanol and water, which 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 re-transported to the reactive distillation column as a raw material reactant; both the benzene removal column and the ethanol distillation column are preferably provided with at least three layers of packing.

[0006] Preferably, it further comprises a side-line buffer tank. The feed port of the side-line buffer tank is connected to the middle discharge port of the column body of the reactive distillation column through a pipeline, and the discharge port of the side-line buffer tank is connected to the upper feed port and the lower feed port of the column body of the reactive distillation column through pipelines respectively. The side-line buffer tank can increase the liquid flux in the column, increase the reaction volume, and strengthen the reaction temperature.

[0007] Preferably, the discharge port of the second condenser is also connected to the top reflux port of the vacuum rectification column through a pipeline.

[0008] Preferably, the discharge port of the third condenser is also connected to the top reflux port of the benzene stripper through a pipeline.

[0009] Preferably, the discharge port of the fourth condenser is also connected to the top reflux port of the ethanol rectification column through a pipeline.

[0010] A continuous production method of diethyl maleate, the specific method is as follows: ethanol, maleic anhydride and a catalyst are transported to a reactive distillation column through a side-line feed pipeline, the azeotropic agent benzene is transported from a benzene-water separation tank to the reactive distillation column through the top reflux port of the reactive distillation column, after each material reacts in the reactive distillation column, the light components composed of benzene, ethanol and water taken from the top of the reactive distillation column are cooled by a first condenser and then enter the benzene-water separation tank for oil-water separation. The benzene phase is refluxed to the top of the reactive distillation column through the benzene-phase outlet on the benzene-water separation tank, and the water phase enters the benzene stripper through the water-phase outlet on the benzene-water separation tank. The reaction liquid at the bottom of the reactive distillation column is transported to a vacuum rectification column through a pipeline at the bottom discharge port for purification; the light components in the vacuum rectification column are cooled by a second condenser and then discharged, and the heavy components in the vacuum rectification column are discharged through a heavy-component discharge pipeline, and the product diethyl maleate is discharged through a side-line discharge pipeline; after the water phase is separated by the benzene stripper, the light components composed of benzene and ethanol taken from the top of the benzene stripper are cooled by a third condenser and then transported to the benzene-water separation tank for reuse, and the heavy components composed of water and ethanol obtained at the bottom of the benzene stripper are transported to an ethanol rectification column. After being separated by the ethanol rectification column, ethanol taken from the top of the ethanol rectification column is used as a raw material and put into the reactive distillation column, and the water obtained at the bottom of the ethanol rectification column is discharged.

[0011] Preferably, after the light components in the vacuum rectification column are cooled by the second condenser, a part is discharged, and the other part is refluxed to the top of the vacuum rectification column.

[0012] Preferably, after the light components composed of benzene and ethanol taken from the top of the benzene stripper are cooled by the third condenser, a part is transported to the benzene-water separation tank for reuse, and the other part is refluxed to the top of the vacuum rectification column.

[0013] Preferably, the heavy components composed of water and ethanol obtained at the bottom of the benzene stripper are transported to an ethanol rectification column. After being separated by the ethanol rectification column, ethanol taken from the top of the ethanol rectification column, a part of the ethanol is used as a raw material and put into the reactive distillation column, and the other part of the ethanol is refluxed to the top of the vacuum rectification column.

[0014] Therefore, the present invention has the following beneficial effects: (1) It includes a vacuum distillation column, a debenzolization column and an ethanol distillation column. The vacuum distillation column is used to purify the bottom material in the reactive distillation column to improve the product purity; the debenzolization column is used to remove the reboiler benzene in the aqueous phase material of the benzene-water separation tank, and then recycle the reboiler benzene to the benzene-water separation tank for reuse. The ethanol distillation column is used to separate ethanol and water from the material at the bottom of the debenzolization column to recycle ethanol, thereby effectively improving the utilization rate of raw materials; (2) A continuous production method of diethyl maleate is provided. By using vacuum distillation technology and atmospheric pressure double-column distillation technology, the purity of the finally obtained product diethyl maleate can reach more than 99.9 wt%, with high product purity, and it can effectively recycle the reboiler benzene and ethanol, effectively improving the utilization rate of raw materials. Description of the Drawings

[0015] Figure 1 It is a connection schematic diagram of the present invention.

[0016] In the figure: reactive distillation column 1, benzene-water separation tank 2, vacuum distillation column 3, debenzolization column 4, ethanol distillation column 5, side-line feed pipeline 6, first condenser 7, second condenser 8, light-component discharge pipeline 9, heavy-component discharge pipeline 10, side-line discharge pipeline 11, third condenser 12, fourth condenser 13, ethanol discharge pipe 14, wastewater pipe 15, side-line buffer tank 16. Detailed Embodiments

[0017] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0018] Such as Figure 1A continuous production system for diethyl maleate shown in the figure includes a reactive distillation column 1, a benzene-water separation tank 2, a vacuum distillation column 3, a benzene removal column 4, an ethanol distillation column 5 and a side-line buffer tank 16. The upper feed port of the tower body of the reactive distillation column is connected with a side-line feed pipeline 6. The top discharge port of the reactive distillation column is connected with a first condenser 7. The discharge port of the first condenser is connected with the feed port of the benzene-water separation tank through a pipeline. The bottom discharge port of the reactive distillation column is connected with the middle feed port of the tower body of the vacuum distillation column through a pipeline. The feed port of the side-line buffer tank is connected with the middle discharge port of the tower body of the reactive distillation column through a pipeline. The discharge port of the side-line buffer tank is connected with the upper feed port and the lower feed port of the tower body of the reactive distillation column respectively through pipelines. The benzene-phase outlet on the benzene-water separation tank is connected with the top reflux port of the reactive distillation column through a pipeline. The water-phase outlet on the benzene-water separation tank is connected with the middle feed port of the tower body of the benzene removal column through a pipeline. The top light-component discharge port of the vacuum distillation column is connected with a second condenser 8. The discharge port of the second condenser is connected with a light-component discharge pipeline 9. The discharge port of the second condenser is also connected with the top reflux port of the vacuum distillation column through a pipeline. The bottom discharge port of the vacuum distillation column is connected with a heavy-component discharge pipeline 10. The middle part of the tower body of the vacuum distillation column is connected with a side-line discharge pipeline 11. The top discharge port of the benzene removal column is connected with a third condenser 12. The discharge port of the third condenser is connected with the feed port of the benzene-water separation tank through a pipeline. The discharge port of the third condenser is also connected with the top reflux port of the benzene removal column through a pipeline. The bottom discharge port of the benzene removal column is connected with the middle feed port of the tower body of the ethanol distillation column through a pipeline. The top discharge port of the ethanol distillation column is connected with a fourth condenser 13. The discharge port of the fourth condenser is connected with an ethanol discharge pipe 14. The discharge port of the fourth condenser is also connected with the top reflux port of the ethanol distillation column through a pipeline. The top discharge port of the ethanol distillation column is connected with a waste water pipe 15.

[0019] A continuous production method of diethyl maleate, and the specific method is as follows: Alcohol, maleic anhydride and a catalyst are transported to a reactive distillation column through a side-line feed pipeline, and the azeotropic agent benzene is transported from a benzene-water separation tank to the reactive distillation column through the top reflux port of the reactive distillation column. After the various materials react in the reactive distillation column, the light components composed of benzene, ethanol and water taken from the top of the reactive distillation column are cooled by a first condenser and then enter the benzene-water separation tank for oil-water separation. The benzene phase is refluxed to the top of the reactive distillation column through the benzene-phase outlet on the benzene-water separation tank, and the water phase enters a benzene stripper through the water-phase outlet on the benzene-water separation tank. The reaction liquid at the bottom of the reactive distillation column is transported through a pipeline at the bottom discharge port to a vacuum distillation column for purification; the light components in the vacuum distillation column are cooled by a second condenser, part of which is discharged, and the other part is refluxed to the top of the vacuum distillation column. The heavy components in the vacuum distillation column are discharged through a heavy-component discharge pipeline, and the product diethyl maleate is discharged through a side-line discharge pipeline; after the water phase is separated by the benzene stripper, the light components composed of benzene and ethanol taken from the top of the benzene stripper are cooled by a third condenser, part of which is transported to the benzene-water separation tank for reuse, and the other part is refluxed to the top of the benzene stripper. The heavy components composed of water and ethanol obtained at the bottom of the benzene stripper are transported to an ethanol distillation column. After being separated by the ethanol distillation column, ethanol (94 wt%) is taken from the top of the ethanol distillation column. Part of the ethanol is put into the reactive distillation column as a raw material, and the other part of the ethanol is refluxed to the top of the vacuum distillation column. The water obtained at the bottom of the ethanol distillation column is discharged.

[0020] The above embodiments are only a preferred solution of the present invention, and do not impose any form of limitation on the present invention. There are other variants and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A continuous production system of diethyl maleate, characterized in that: It comprises a reaction distillation tower (1), a benzene-water separation tank (2), a vacuum distillation tower (3), a debenzene tower (4) and an ethanol distillation tower (5); The upper feed port of the reaction distillation tower is connected to a side line feed pipeline (6), the top discharge port of the reaction distillation tower is connected to a first condenser (7), the discharge port of the first condenser is connected to the feed port of the benzene water separation tank through a pipeline, and the bottom discharge port of the reaction distillation tower is connected to the middle feed port of the tower body of the vacuum distillation tower through a pipeline; The benzene phase outlet on the benzene water separation tank is connected to the top reflux port of the reactive distillation tower through a pipeline, and the water phase outlet on the benzene water separation tank is connected to the feed port in the middle of the tower body of the debenzene tower through a pipeline; The light component discharge port at the top of the vacuum distillation tower is connected to a second condenser (8), the discharge port of the second condenser is connected to a light component discharge pipeline (9), the bottom discharge port of the vacuum distillation tower is connected to a heavy component discharge pipeline (10), and the middle part of the tower body of the vacuum distillation tower is connected to a side line discharge pipeline (11); The top discharge port of the debenzene tower is connected to a third condenser (12), the discharge port of the third condenser is connected to the feed port of the benzene water separation tank through a pipeline, and the bottom discharge port of the debenzene tower is connected to the feed port in the middle of the tower body of the ethanol distillation tower through a pipeline; The top discharge port of the ethanol distillation tower is connected to a fourth condenser (13), the discharge port of the fourth condenser is connected to an ethanol discharge pipe (14), and the top discharge port of the ethanol distillation tower is connected to a wastewater pipe (15).

2. A continuous production system of diethyl maleate according to claim 1, characterized in that, It also includes a side line buffer tank (16), the feed port of the side line buffer tank is connected to the discharge port in the middle of the tower body of the reaction distillation tower through a pipeline, and the discharge port of the side line buffer tank is respectively connected to the feed port at the top of the tower body and the feed port at the bottom of the tower body of the reaction distillation tower through pipelines.

3. A continuous production system of diethyl maleate according to claim 1, characterized in that, The discharge port of the second condenser is also connected to the top reflux port of the vacuum distillation tower through a pipeline.

4. A continuous production system of diethyl maleate according to claim 1, characterized in that, The discharge port of the third condenser is also connected to the top reflux port of the debenzene tower through a pipeline.

5. A continuous production system of diethyl maleate according to claim 1, characterized in that, The discharge port of the fourth condenser is also connected to the top reflux port of the ethanol distillation tower through a pipeline.

6. A method for continuously producing diethyl maleate using the diethyl maleate continuous production system as claimed in claim 1, characterized in that: The specific method is as follows: ethanol, maleic anhydride and a catalyst are transported to a reaction distillation tower through a side feed pipeline; an azeotropic agent benzene is transported from a benzene water separation tank to the reaction distillation tower through a tower top reflux port of the reaction distillation tower; after each material reacts in the reaction distillation tower, a light component composed of benzene, ethanol and water is extracted from the tower top of the reaction distillation tower, cooled by a first condenser, and then enters a benzene water separation tank for oil-water separation; the benzene phase is refluxed to the tower top of the reaction distillation tower through a benzene phase outlet on the benzene water separation tank; the water phase enters a debenzene tower through a water phase outlet on the benzene water separation tank; the tower bottom reaction liquid of the reaction distillation tower is transported to the tower bottom through a pipeline through a tower bottom discharge port; The product is sent to a vacuum distillation tower for purification; the light components in the vacuum distillation tower are discharged after being cooled by the second condenser, the heavy components in the vacuum distillation tower are discharged through the heavy component discharge pipeline, and the product diethyl maleate is discharged from the side line discharge pipeline; after the aqueous phase is separated by a debenzene tower, the light components composed of benzene and ethanol are taken out from the top of the debenzene tower, cooled by the third condenser, and transported to a benzene-water separation tank for reuse, and the heavy components composed of water and ethanol are obtained in the kettle of the debenzene tower and transported to an ethanol distillation tower. After separation in the ethanol distillation tower, ethanol is taken out from the top of the ethanol distillation tower and fed into a reaction distillation tower as a raw material, and water is obtained in the kettle of the ethanol distillation tower and discharged.

7. The method for continuously producing diethyl maleate according to claim 6, wherein: After the light components in the vacuum distillation tower are cooled by the second condenser, a part of them is discharged and the other part is refluxed to the top of the vacuum distillation tower.

8. The method for continuous production of diethyl maleate according to claim 6, wherein: The light components consisting of benzene and ethanol extracted from the top of the debenzene tower are cooled by the third condenser, and a part of them is transported to the benzene-water separation tank for reuse, and the other part is refluxed to the top of the debenzene tower.

9. The method for continuous production of diethyl maleate according to claim 6, wherein: The heavy components composed of water and ethanol obtained in the debenzene tower kettle are transported to the ethanol distillation tower. After separation in the ethanol distillation tower, ethanol is extracted from the top of the ethanol distillation tower. Part of the ethanol is fed into the reaction distillation tower as a raw material, and the other part of the ethanol is refluxed to the top of the vacuum distillation tower.

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