Technical process of preparing high-purity L-lactic acid

Abstract

The invention discloses a making method of high-purity L-lactic acid, which comprises the following steps: a) extracting; crystallizing; decoloring; proceeding ion exchange or film separation; transmitting predisposed L-lactic acid into condenser under 0.5-0.95Mpa at 50-90 deg.c to condensate; b) transmitting L-lactic acid into at least two-grade cascading short-path distill devices to distill; setting one-grade short-path under 50-500Pa at 50-130 deg.c to distill; transmitting the heavy component into two-grade short-path distill device; collecting light component to obtain high-purity L-lactic acid; distilling heavy component from two-grade short-path distill device under 10-500Pa at 100-120 deg.c to distill; collecting light component as high-purity product.

Description

technical field [0001] The invention belongs to the refining field of high-purity L-lactic acid, and mainly relates to the L-lactic acid product obtained from L-lactic acid produced by a fermentation method through a series of extraction processes, through concentration and short-range refining, to obtain high-purity polymerization-grade L-lactic acid. It can be used as a raw material for direct polycondensation to produce polylactic acid. Background technique [0002] L-lactic acid is an important organic acid, which has broad application prospects in food, beverage, feed, modern medicine, modern pesticide, daily chemical industry, papermaking and electronics industries. In recent years, people have used L-lactic acid as a raw material to make a new biodegradable environmentally friendly material - polylactic acid (PLA). The development of this technology has made L-lactic acid products attract people's attention, and has become one of the most popular biochemical products...

AI Technical Summary

Problems solved by technology

However, the application of domestic short-path distillation equipment on L-lactic acid is still in the trial stage, and there are still deficiencies in the purification effect, product grade and purification yield of L-lactic acid in terms of process technology scheme and short-path distillation equipment, especially to obtain high-purity polymerization Grade L-lactic acid also needs high yield, which cannot be achieved by the current general short-path distillation method.

[0005] In the current general short-path distillation process, crude lactic acid is used as the starting material for short-path distillation. However, using crude lactic acid as a raw material seems to reduce the extraction cost, but due to too many impurities in the short-path distillation process, it is easy to carry Therefore, it is difficult to guarantee the quality standard of high-purity polymer grade products, and only general heat-resistant L-lactic acid can be obtained

If you want to achieve high-quality L-lactic acid, the distillation efficiency and capacity will be reduced, and a large number of heavy components will make recycling difficult