Enhanced micro-interface reaction system and method for preparing lactide from lactic acid

Abstract

The invention provides an enhanced micro-interface reaction system for preparing lactide from lactic acid. The enhanced micro-interface reaction system comprises a lactic acid raw material tank and an oligomerization rectification reactor, wherein the lactic acid raw material tank is connected with the oligomerization rectification reactor; an external micro-interface unit is arranged in the oligomerization rectification reactor; a second reboiler is arranged at the bottom of the first lactide rectification reactor, and materials discharged from the bottom of the first lactide rectification reactor are gasified by the second reboiler and then are introduced into a first micro-interface generator in the first lactide rectification reactor; a second micro-interface generator is arranged below the first micro-interface generator; the first lactide rectification reactor is connected in parallel with a second lactide rectification reactor; and a hydraulic micro-interface generator is arranged in the second lactide rectification reactor. The reaction system provided by the invention can reduce reaction temperature and improve reaction efficiency.

Description

technical field [0001] The invention relates to the field of lactide preparation, in particular to an enhanced micro-interface reaction system and method for preparing lactide from lactic acid. Background technique [0002] The production, development and utilization of lactide have been paid more and more attention in recent years, mainly because the ring-opening polymerization of lactide is an effective method for preparing high molecular weight polylactic acid. Polylactic acid is a promising biodegradable material. Because the final products of its decomposition in the natural environment are carbon dioxide and water, it is non-toxic and harmless to the environment, and has good biocompatibility and biodegradability. It is an excellent medical polymer material due to its excellent mechanical properties and easy processing and molding. The ring-opening polymerization of lactide is an effective method to prepare high-molecular-weight polylactic acid, and the molecular weig...

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Problems solved by technology

[0006] Among them, the oligomerization reaction process in the first step is dehydration between lactic acid molecules. Since the oligomerization reaction itself is a reversible reaction, the presence of water will dilute the reaction materials and affect the reaction rate, thereby affecting the normal progress of the reaction process.

The efficiency of the separation system of the lactide synthesis reaction in the second step is low. Due to the high viscosity of the system and the small separation interface, the generated lactide cannot be taken out in time to make the esterification reaction reach an equilibrium state, causing the oligomer to proceed in the direction of the polymerization reaction. , reducing the lactide product yield

Long residence time in the reaction process leads to more by-products and indirectly affects the quality of the product

The reaction temperature is higher, which increases the production cost

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