Method for preparing lactide from lactic acid

A lactide and lactic acid technology, applied in chemical instruments and methods, organic chemistry, molecular sieve catalysts, etc., can solve the problems of harsh reaction conditions and complicated process flow, and achieve the effect of simple equipment, high reactivity and mild reaction conditions

Pending Publication Date: 2022-05-06
CHINA PETROLEUM & CHEM CORP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The core-shell molecular sieve catalyst used in the present invention can complete the synthesis of lactide in one step from lactic acid under normal pressure conditions, which overcomes the disadvantages of harsh reaction conditions and complicated process flow in the existing lactide preparation process.

Method used

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  • Method for preparing lactide from lactic acid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] (1) According to the molar ratio of silica sol: sodium hydroxide: tetraethylammonium hydroxide: water, each component is 1:0.3:0.25:100, mix each component to prepare Si-Beta mother liquor, and then press molecular sieve and silica sol ( SiO 2 content meter) the molar ratio is 10:1, add H-Beta molecular sieve (particle size is about 500nm, SiO 2 / Al 2 O 3 = 15), stand at 150°C for 48h crystallization, filter and separate after crystallization, wash with deionized water until neutral, dry at 100°C for 12h, calcinate at 550°C for 5h to obtain Si-Beta / H-Beta core-shell molecular sieve catalyst . In the prepared catalyst, the H-Beta content was 91.9% and the Si-Beta content was 8.1% by mass.

[0034] (2) According to the mass ratio of Si-Beta / H-Beta core-shell molecular sieve and lactic acid is 1:2, and the solid-liquid ratio of Si-Beta / H-Beta core-shell molecular sieve and toluene is 1:20 (g:mL), the catalyst , L-lactic acid with a mass concentration of 80%, and toluen...

Embodiment 2

[0036] (1) Mix the components uniformly according to the molar ratio of ethyl orthosilicate: sodium hydroxide: tetraethyl ammonium hydroxide: water: 1:0.2:0.25:80, and then press molecular sieve and silica sol (with SiO 2 content) in a molar ratio of 10:1, add H-Beta molecular sieve (particle size is about 200nm, SiO 2 / Al 2 O 3 =10), stand at 140°C for 24h crystallization, filter and separate after crystallization, wash with deionized water until neutral, dry at 100°C for 12h, calcinate at 550°C for 5h to obtain Si-Beta / H-Beta core-shell molecular sieve catalyst . In the prepared core-shell catalyst, the H-Beta content was 92.6% and the Si-Beta content was 7.4% by mass.

[0037] (2) According to the mass ratio of Si-Beta / H-Beta core-shell molecular sieve and lactic acid is 1:1, and the solid-liquid ratio of Si-Beta / H-Beta core-shell molecular sieve and toluene is 1:10 (g:mL), the catalyst , L-lactic acid with a mass concentration of 80%, and toluene were mixed, and the r...

Embodiment 3

[0039] (1) Mix the components uniformly according to the molar ratio of silica: sodium hydroxide: tetraethylammonium hydroxide: water to 1:0.4:0.4:120, and then press molecular sieve and silica sol (SiO 2 Content calculation) the molar ratio is 20:1, add H-Beta molecular sieve (particle size is about 2μm, SiO 2 / Al 2 O 3 =40), stand at 160°C for 72h crystallization, filter and separate after crystallization, the product particles are washed with deionized water until neutral, dried at 100°C for 12h, and calcined at 550°C for 5h to obtain Si-Beta / H-Beta core-shell Molecular sieve catalyst. In the prepared core-shell catalyst, the H-Beta content is 95.5% and the Si-Beta content is 4.5% by mass.

[0040] (2) According to the mass ratio of Si-Beta / H-Beta core-shell molecular sieve and lactic acid is 1:3, and the solid-liquid ratio of Si-Beta / H-Beta core-shell molecular sieve and toluene is 1:30 (g:mL), the catalyst , L-lactic acid with a mass concentration of 80%, and toluene ...

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Abstract

The invention relates to a method for preparing lactide from lactic acid, which comprises the following steps: mixing a lactic acid solution with an organic solvent, adding a Si-Beta / H-Beta core-shell molecular sieve, carrying out a stirring reflux reaction at normal pressure and a certain temperature, adding water after the reaction is completed, carrying out liquid-liquid two-phase separation, and carrying out reduced pressure distillation on an organic phase to obtain a lactide product, the core shell of the Si-Beta / H-Beta core-shell molecular sieve is a catalyst which takes an H-Beta molecular sieve as a core and Si-Beta as a shell, and the catalyst comprises the following components in percentage by mass: 91.1%-96.5% of the H-Beta molecular sieve and 3.5%-8.9% of the Si-Beta molecular sieve. The catalyst adopted by the invention can complete the synthesis of lactide from lactic acid by a one-step method under normal pressure, and overcomes the defects of harsh reaction conditions, complex process flow and the like in the existing lactide preparation.

Description

technical field [0001] The invention belongs to the field of synthesis of biodegradable materials, and in particular relates to a method for preparing lactide from lactic acid. Background technique [0002] The uncontrolled large-scale production of petroleum-based plastics and the abuse of non-degradable disposable petroleum-based plastic products have caused plastic waste pollution to become one of the important pollution sources of the human ecological environment. The use of renewable resources, the synthesis of green and clean chemical reactions, the production of environmentally friendly and biodegradable plastics are considered to be one of the effective ways to solve the above problems, and are also related to the protection of the ecological environment and the development of circular economy and sustainable economic development. important move. Among many biodegradable materials, polylactic acid combines resource renewability, environmental and biodegradability, b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12B01J29/80B01J29/70
CPCC07D319/12B01J29/7007B01J29/80
Inventor 张通白毓黎白富栋孙启梅李澜鹏彭绍忠乔凯
Owner CHINA PETROLEUM & CHEM CORP
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