CN-121971869-A - Efficient energy-saving system, method and application for separating maleic acid ester from maleic anhydride esterification liquid

CN121971869ACN 121971869 ACN121971869 ACN 121971869ACN-121971869-A

Abstract

The invention belongs to the technical field of chemical separation, and discloses a high-efficiency energy-saving system, a method and application for separating maleic acid ester from maleic anhydride esterification liquid, wherein the system comprises an esterification reaction device, a reduced pressure rectifying tower, a partition rectifying tower, a first condenser, a second condenser, a first reboiler and a second reboiler, the esterification reaction device, the vacuum rectifying tower and the partition rectifying tower are sequentially connected, the first condenser and the first reboiler are connected with the vacuum rectifying tower, and the second condenser and the second reboiler are connected with the partition rectifying tower. The invention adopts a decompression rectification and partition wall rectification coupling system, can effectively avoid the problem that the intermediate product monomethyl maleate is reversely converted into maleic anhydride and the product purity caused by the maleic anhydride is low, improves the product yield, obviously reduces the energy consumption in the methanol use and dimethyl maleate product separation process in the reaction device, and improves the product purity.

Inventors

LI HONG
WANG HONGBIN
DING QIUYAN
LIU SHUN
GAO XIN

Assignees

天津大学

Dates

Publication Date: 20260505
Application Date: 20260210

Claims (10)

1. The efficient energy-saving system for separating maleic acid ester from maleic anhydride esterification liquid is characterized by comprising an esterification reaction device, a vacuum rectification tower, a partition rectification tower, a first condenser, a second condenser, a first reboiler and a second reboiler, wherein the esterification reaction device, the vacuum rectification tower and the partition rectification tower are sequentially connected, the first condenser and the first reboiler are both connected with the vacuum rectification tower, the second condenser and the second reboiler are both connected with the partition rectification tower, and methanol and maleic anhydride can be subjected to esterification reaction in the esterification reaction device and the obtained first mixture containing methanol, water, monomethyl maleate and dimethyl maleate.
2. The efficient and energy-saving system as set forth in claim 1, wherein the vacuum rectification tower comprises a vacuum tower body, a vacuum tower input end, a vacuum tower top output end and a vacuum tower bottom output end, wherein the vacuum tower body is arranged along the vertical direction, and the vacuum tower body is internally provided with a rectification section and a stripping section in a communicating way, the rectification section is arranged above the stripping section; The partition rectifying tower comprises a partition rectifying tower body, a partition rectifying tower input end, a partition rectifying tower top output end, a partition rectifying tower bottom output end, a partition plate and a side extraction section output end, wherein the partition rectifying tower body is arranged along the vertical direction, the partition plate is arranged in the partition rectifying tower body in a communicated manner, the partition plate is used for dividing the partition rectifying tower body into a prefractionation section, a public rectifying section, a side extraction section and a public stripping section in a communicated manner, the public rectifying section is arranged at the upper part in the bulkhead rectifying tower body, the public stripping section is arranged at the lower part in the bulkhead rectifying tower body, the prefractionation section and the side line extraction section are arranged in the bulkhead rectifying tower body between the public rectifying section and the public stripping section, and the prefractionation section is arranged close to the input end of the bulkhead rectifying tower; the separator rectifying tower comprises a separator rectifying tower body, a side line extraction section, a separator rectifying tower top output end, a separator rectifying tower bottom output end, a separator rectifying tower top output end, a separator rectifying tower bottom output end and a separator rectifying tower bottom output end, wherein the separator rectifying tower input end and the side line extraction section output end are both communicated with each other and are arranged on the separator rectifying tower body; The input end of the esterification reaction device can be used for inputting methanol and maleic anhydride, the output end of the esterification reaction device can be used for outputting a first mixture containing methanol, water, monomethyl maleate and dimethyl maleate, which is obtained after the esterification reaction of the methanol and the maleic anhydride, the output end of the esterification reaction device is tightly connected with the input end of the vacuum tower, and the first mixture can be input into the vacuum tower through the input end of the vacuum tower; the output end of the pressure reducing tower top is tightly connected with the upper part of the rectifying section through a first condenser, the output end of the pressure reducing tower top is tightly connected with the input end of the partition rectifying tower through the first condenser, the output end of the pressure reducing tower bottom is tightly connected with the lower part of the stripping section through a first reboiler, and the output end of the pressure reducing tower bottom is also connected with the esterification reaction device through the first reboiler; The output end of the top of the partition wall rectifying tower is closely connected with the upper part of the public rectifying section through a second condenser, the output end of the top of the partition wall rectifying tower also directly outputs product methanol through the second condenser, the output end of the bottom of the partition wall rectifying tower is closely connected with the lower part of the public stripping section through a second reboiler, and the output end of the bottom of the public stripping section also directly outputs high-purity dimethyl maleate product through the second reboiler.
3. The efficient and energy-saving system as claimed in claim 2, wherein the esterification reaction device is a batch reactor, a fixed bed reactor or a reactive rectifying tower.
4. The energy-efficient system according to claim 2 or 3, wherein the raw material is a mixture of maleic anhydride and methanol after reaction in the esterification reaction device, and the mixture contains 5-20% by mass of methanol, 10-40% by mass of monomethyl maleate, 5-20% by mass of water and 30-70% by mass of dimethyl maleate.
5. A method for separating maleic acid ester from maleic anhydride esterification liquid by using the energy-efficient system according to any one of claims 1 to 4, comprising the steps of: the raw materials are methanol and maleic anhydride which are subjected to esterification reaction in an esterification reaction device, the obtained mixture containing methanol, water, monomethyl maleate and dimethyl maleate is subjected to reduced pressure rectification separation in a reduced pressure rectifying tower, the methyl maleate which is not subjected to di-esterification is obtained from a tower kettle and is returned to the esterification reaction device for continuous reaction, the mixture of the methanol, the water and the dimethyl maleate is extracted from the top of the reduced pressure rectifying tower and is further subjected to separation in a partition rectifying tower, the high-purity dimethyl maleate product is obtained from the tower kettle, the water extracted from a side line extraction section is subjected to further treatment, and the methanol extracted from the top of the tower is returned to the esterification reaction device for continuous reaction.
6. The method according to claim 5, wherein the vacuum rectification column has an operating pressure in the range of 0.1 to 50 kPa, an operating temperature in the range of 50 to 180℃and a total theoretical plate number in the range of 20 to 60.
7. The method of claim 5, wherein the packing of the rectifying section and stripping section is stainless steel corrugated wire mesh packing, theta ring packing, foam silicon carbide, wire mesh silicon carbide.
8. The method according to claim 5, wherein the theoretical plate number of the rectifying section is 10-40, the theoretical plate number of the stripping section is 10-40, and the reflux ratio is 1:1-10:1.
9. The method according to claim 5 to 8, wherein the pressure range of the dividing wall rectifying column is normal pressure, the operating temperature range is 50-150 ℃, the total theoretical plates of the column is 20-70, the theoretical plates of the common stripping section is 5-30, the theoretical plates of the common rectifying section is 5-30, the theoretical plates of the prefractionation section is 15-45, the theoretical plates of the side draw section is 15-45, and the reflux ratio is 1:1-10:1.
10. The use of the energy efficient system according to any one of claims 1 to 4 for separating maleate from maleic anhydride esterification liquid.

Description

Efficient energy-saving system, method and application for separating maleic acid ester from maleic anhydride esterification liquid Technical Field The invention belongs to the technical field of chemical separation, and particularly relates to a high-efficiency energy-saving system, a method and application for separating maleic acid ester from maleic anhydride esterified liquid by using a decompression-partition wall rectification coupling technology. Background Dimethyl maleate (DMM, molecular formula is C 6H8O4) is an important organic chemical intermediate, is colorless transparent oil-like liquid with irritation, is often used as a solvent for producing pesticides, water purifying agents, optical materials, plasticizers, paint, coating materials and the like, and can be used as a basic raw material for producing fine chemical products such as 1, 4-butanediol, tetrahydrofuran, gamma-butyrolactone, dimethyl succinate and the like through catalytic reaction. The above applications all put high demands on the purity of the dimethyl maleate. At present, maleic acid dimethyl ester is produced by taking maleic anhydride and methanol as raw materials to carry out a di-esterification reaction, and the reaction route is divided into two steps, namely, the first step is that maleic anhydride and methanol are spontaneously esterified to generate an intermediate product monomethyl maleate, no additional catalyst is needed, and the second step is that the monomethyl maleate continuously reacts with the methanol under the action of the catalyst to obtain the product dimethyl maleate. In the actual industrial process, the reaction liquid generally contains unreacted raw materials, intermediate product monomethyl ester, dimethyl ester and water, if the reaction liquid is separated by adopting a conventional rectification mode, the problems of 1) complex components of crude dimethyl maleate products, high-purity products obtained by connecting a plurality of rectification towers in series, longer process flow and higher equipment investment and energy consumption are easily caused, and 2) the monomethyl maleate is easily subjected to reverse conversion at high temperature to generate raw material maleic anhydride, so that the product yield is obviously reduced. The following patent documents related to the present application have been found, and specific disclosures thereof are as follows: 1. The Chinese patent publication CN106187775B proposes a method for purifying dimethyl maleate, which mainly comprises the steps of firstly dissolving a crude product of dimethyl maleate in a solvent (methanol or tetrahydrofuran), then adsorbing impurity dimethyl fumarate by using a molecular imprinting adsorption column, then removing the solvent by a rotary evaporation method, and finally effectively removing trans-isomerism impurity dimethyl fumarate by a distillation separation method to obtain a dimethyl maleate product. However, the method does not consider that the monoester which is not completely reacted exists in the crude product, so that the yield of diester is reduced, and the preparation process of the molecular imprinting adsorption column is complex. 2. The chinese patent publication CN221889905U proposes a device for producing dimethyl maleate, which comprises a monomethyl ester reactor, a dimethyl ester reactor and a catalytic distillation deep reactor, wherein the method can realize partial integration of reaction and separation, but the products obtained from the bottom of the catalytic distillation tower still need further purification, the whole production flow is complex, and the equipment investment and the running cost are high. 3. Chinese patent publication CN114984866B discloses and reports a system and a method for preparing dimethyl maleate, wherein the method mainly comprises the steps of generating monomethyl maleate from raw materials maleic anhydride and methanol in a monoesterification reactor, supplementing methanol into a di-esterification pre-reactor, enabling materials obtained in the pre-reactor to enter a dividing wall reaction rectifying tower for continuous esterification reaction, and finally obtaining a dimethyl maleate product in a tower kettle. The method utilizes reaction heat and adopts a membrane separation device to separate methanol and water, so that the energy consumption is reduced, but the method does not realize that maleic acid monoester is unstable at a higher temperature in the di-esterification process and is easy to reversely convert into maleic anhydride and methanol, so that maleic anhydride inevitably exists in a tower kettle product, the boiling points of the maleic anhydride and the maleic acid dimethyl ester are relatively close, and the subsequent separation is difficult to carry out. Therefore, aiming at the crude product of the dimethyl maleate obtained in the esterification process of maleic anhydride, development of a separation process with high efficiency, en