Method for purifying acrylic acid

Abstract

The invention relates to the process for purifying acrylic acid which comprises using novel organic extracting agent to separate acrylic acid from its water solution, then removing light compositions such as water and acetic acid by azeotropic fractional distillation, wherein the organic extracting agent comprises toluene, acetic ether, butyl acetate, butyl acetate, propionic ether, diisobutyl ketone, isophorone, methyl phenyl ether or their mixture, preferably the composite compound of toluene with isobutyl phenylacetate, the mass ratio of toluene and isobutyl phenylacetate is between 1:1-1:50, preferably 1:2-1:12. The process according to the invention can realize high acetic acid removing ratio.

Description

technical field

[0001] The present invention relates to a method for purifying acrylic acid. Background technique

[0002] Acrylic acid is produced by gas-phase oxidation of propylene and / or acrolein under the action of a catalyst. The gaseous product is cooled and absorbed by water to obtain an aqueous acrylic acid solution containing 25-50% acrylic acid. In addition to acrylic acid, there are acetic acid and various other trace impurities in the aqueous acrylic acid solution, such as formaldehyde, acrolein, propionic acid, acetone, maleic acid, furfural and acrylic acid dimer. It is quite difficult to separate acrylic acid from its aqueous solution directly by simple rectification method, because acrylic acid and water easily form azeotrope, which makes dehydration difficult. In addition, acrylic acid is prone to self-polymerization, resulting in a decrease in yield. In industry, azeotropic dehydration and solvent extraction are usually used to refine and purify acrylic...

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