Synthesis method and device for rapidly producing lactide at high yield

A synthesis device and synthesis method technology, applied in chemical instruments and methods, sub-atmospheric process, organic chemistry, etc., can solve the problems of high cost, long residence time, low efficiency, etc., and achieve high yield and simple operation , high yield effect

Active Publication Date: 2020-05-15
NANJING UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Purpose of the invention: Aiming at the problems of long residence time, low efficiency and high cost in the synthesis of commercialized lactide in the prior art, a rapid and ...

Method used

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  • Synthesis method and device for rapidly producing lactide at high yield
  • Synthesis method and device for rapidly producing lactide at high yield

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] The 90% L-lactic acid raw material 1 enters the oligomerization reactor 6 at a flow rate of 10 g / h through the raw material pump 2. The oligomerization reactor 6 is a TLNS falling film reactor, and the operating conditions of the reactor are 80° C. and 1 KPa absolute pressure. Dehydration and oligomerization, the dehydration oligomers pass through the oligomerization discharge / circulation pump 7 to control the reflux ratio of 1000:1, and return to the side line feed port of the oligomerization reactor 6 to continue the reaction, and the rectification tower 11 at the top of the oligomerization reactor 6 returns lactic acid , Control the tower top temperature to 40°C by reflux. Oligomer 9 has a molecular weight of 500 Da.

[0052] The oligomer 9 enters the oligomer purification reactor 18, which is an RFJL packed rectification column with side feed, and the operating conditions are: absolute pressure 1KPa, tower top temperature 20°C. The removed acid, water and dimer...

Embodiment 2

[0057] The 90% L-lactic acid raw material 1 is mixed with the catalyst zinc oxide 3 by the raw material pump 2 at a flow rate of 20g / h and then enters the oligomerization reactor 6. The oligomerization reactor 6 is a TLNS falling film reactor, and the operating condition of the reactor is a temperature of 120°C 1. Carry out dehydration and oligomerization under the condition of absolute pressure 1KPa, the dehydration oligomer passes through the oligomerization discharge / circulation pump 7 to control the reflux ratio of 300:1, and returns to the side feed port of the oligomerization reactor 6 to continue the reaction, and the oligomerization reactor 6 Lactic acid is refluxed in the top rectifying column 11, and the temperature at the top of the column is controlled to 60° C. by reflux. Oligomer 9 has a molecular weight of 1100 Da.

[0058] The oligomer 9 enters the oligomer purification reactor 18, which is an RFJL packed rectification column with side feed, and the operati...

Embodiment 3

[0063]The 90% L-lactic acid raw material 1 is mixed with the catalyst zinc acetate 3 at a flow rate of 50g / h by the raw material pump 2 and then enters the oligomerization reactor 6. The oligomerization reactor 6 is a WEF thin film evaporation reactor, and the operating condition of the reactor is a temperature of 180°C 1. Carry out dehydration and oligomerization under the condition of absolute pressure 100KPa, the dehydration oligomer passes through the oligomerization discharge / circulation pump 7 to control the reflux ratio of 20:1, and returns to the side feed port of the oligomerization reactor 6 to continue the reaction, and the oligomerization reactor 6 Lactic acid is refluxed in the top rectifying column 11, and the temperature at the top of the column is controlled to 70° C. by reflux. Oligomer 9 has a molecular weight of 800 Da.

[0064] The oligomer 9 enters the oligomer purification reactor 18, which is an RFJL packed rectification column with side feed, and th...

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Abstract

The invention discloses a synthesis method and device for rapidly producing lactide at high yield. The method comprises the steps: adding a lactic acid single component or lactic acid into a catalystdouble component, enabling the mixture to enter an oligomer preparation system through a mixer, increasing the residence time through bottom circulation, synthesizing oligomeric lactic acid, and enabling a gas-phase component to pass through a rectification system, so as to improve the yield of oligomeric lactic acid; removing unreacted lactic acid and water from the oligomeric lactic acid througha purification device; and adding a catalyst into the light-component-removed oligomeric lactic acid, allowing the mixture to pass through a mixer, allowing the mixture to enter a depolymerization reactor, depolymerizing so as to obtain lactide, allowing heavy components to enter the depolymerization reactor again through reflux, and allowing light components to pass through a purification and recovery system so as to obtain the lactide product. With the adoption of the device, lactide can be efficiently synthesized, crude lactide with the yield of 94-98% can be obtained within short residence time of 0.5-5 minutes, the molecular weight of the heavy-component polylactic acid is slowly increased, and the heavy-component polylactic acid can be returned for depolymerization; after the lightcomponents pass through a simple purification system, the content of L-lactide, D-lactide or DL-lactide in the lactide product is 94%-98%, and the content of meso-lactide is 0.5%-5.5%.

Description

technical field [0001] The invention belongs to the field of synthesizing monomers of environment-friendly / biomedical degradable materials, in particular to a high-efficiency synthesis process of lactide, in particular to a rapid and high-yield synthesis method and device for lactide. Background technique [0002] With the development of the times, the use of petroleum-based non-degradable plastics has become more and more widespread, but it has also brought many environmental pollution problems. At the same time, the demand for non-renewable petroleum resources for general-purpose plastics also affects the issue of sustainable development. Polylactic acid is a green polymer material with a wide range of uses. It is suitable for extrusion, injection molding, blister and other processing. After being discarded, it can be degraded into carbon dioxide and water in the natural environment. It has little environmental pollution and is the solution to "white pollution". One of the...

Claims

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Application Information

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IPC IPC(8): C07D319/12
CPCC07D319/12B01J3/006B01J19/0013B01J19/0006B01J8/0015B01J2208/00132B01J2208/0015C08G63/08C08J11/10C08J11/12
Inventor 江伟齐运彪孙平黄伟李爱民张全兴
Owner NANJING UNIV
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