Reaction strengthening method and device for producing lactide by lactic acid liquid-phase one-step method

Abstract

The invention discloses a reaction process strengthening method and device for producing lactide from lactic acid through a one-step method. The invention provides a means and a device for recycling an entrainer in the device and improving the conversion per pass of the reaction. L-lactic acid or D-lactic acid is used as a raw material, under the action of a catalyst, a lactic acid dehydration reaction is performed in an organic solvent in a boiling state, steam generated in the reaction process is condensed and then subjected to phase separation, one or a combination of a salt chemical and a physical water absorbent is added in the phase separation process, and the lactic acid is obtained. Continuously refluxing the evaporated organic solvent into the reactor to finally obtain an organic solvent dissolved with an L-lactide or D-lactide product; in the reaction process, the organic solvent continuously removes water generated in the reaction process through azeotropy; according to the method provided by the invention, the salt and the physical water absorbent are added, so that trace moisture in the reflux organic solvent can be removed, the conversion per pass and rate of the reaction are improved, and the production cost of one-step production of lactide from lactic acid is reduced.

Description

technical field [0001] The invention belongs to the technical field of polymer material production, and relates to a preparation method and device for a chemical intermediate, in particular to a method for strictly removing trace moisture in the reflux liquid in the process of catalyzing lactic acid to directly synthesize lactide, thereby improving the Method and device for enhancing the yield of lactide. Background technique [0002] Polylactic acid is a kind of degradable plastic with good mechanical strength and biocompatibility, and has a wide range of application prospects and fields of application. With the continuous maturity of polylactic acid production technology and the continuous increase of market demand, the production of polylactic acid by the route of non-food crops → lactic acid → lactide → polylactic acid has begun to enter a period of industrial development. At present, most of the high molecular weight polylactic acid produced at home and abroad is obtai...

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Problems solved by technology

[0007] Aiming at the problem of low reaction rate and single-pass yield in the prior art, the present invention finds that it is related to the strict removal of trace moisture, and the salting-out phase separation technology can effectively increase the mass transfer capacity of the two-liquid phase separation in the reflux liquid

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