Method for preparing glycollic acid by glycol

Abstract

The invention relates to a method for preparing glycollic acid by glycol, which comprises a step of performing a reaction of glycol in the oxygen atmosphere under the condition of existence of solvent and catalysts, so as to prepare glycollic acid, wherein water is used as the solvent; V2O5 and Al2O3 are used as the catalysts; the adding weight ratio of glycol to water is 1.0:(4.0-8.0); the usingamounts of the catalysts take the amount of glycol as the reference; the using amount of V2O5 is in the range of 0.01 to 0.18 weight percent; the using amount of Al2O3 is in the range of 0.03 to 0.21weight percent; the reaction pressure is in the range of 0.20 to 0.50MPa; the reaction temperature is in the range of 120 to 155 DEG C; and the reaction time is in the range of 2.0 to 5.0 hours. The method has short process flow. The preparation of glycollic acid by glycol can be realized in one step. The used catalysts have low price and good effect. Both the conversion rate of glycol and the selectivity of glycollic acid are ideal. A reaction product is also easy to refine and purify, so that the high-purity glycollic acid product with high quality can be obtained.

Description

technical field [0001] The invention relates to a method for preparing glycolic acid, in particular to a method for preparing glycolic acid by using ethylene glycol as a raw material through oxidation and disproportionation reactions. Background technique [0002] In the past, glycolic acid was mainly used in the manufacture of boiler descaling agents, cleaning agents, leather tanning agents and chelating agents for metal ions. In recent years, it has been widely used as an external skin agent for cosmetics and external medicines. Due to its small molecular weight, glycolic acid can effectively penetrate skin pores and have a very good moisturizing effect, so it is widely respected by the medical and beauty circles. Polyglycolic acid and copolymers of glycolic acid and lactic acid prepared from glycolic acid have excellent biodegradability and biocompatibility, and can be degraded and metabolized into carbon dioxide and water in the body to be excreted, so they can be used t...

AI Technical Summary

Problems solved by technology

However, in the prior art, glyoxal is usually produced by ethylene glycol through an oxidation reaction. Essentially, the existing glyoxal disproportionation method for producing glycolic acid is prepared by a two-step process using ethylene glycol as a raw material, so its disadvantages is a long process

In addition, the oxidation of ethylene glycol to glyoxal generally adopts high-temperature gas phase reaction, and the catalyst uses noble metals such as pure silver, so the reaction yield is not ideal, generally only about 60%, so the production cost is very high

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