METHOD FOR PURIFYING (METH)ACRYLIC ACID OBTAINED BY OXIDIZING A GASEOUS SUBSTRATE

摘要

The aim of the invention is to purify (meth)acrylic acid obtained by the catalytic or redox oxidation of a gaseous substrate constituted of propane and/or propylene and/or of acrolein during the production of acrylic acid, and of isobutane and/or isobutene and/or tert-butyl alcohol and/or of methacrolein during the production of methacrylic acid. To this end: the gaseous reaction mixture is (1) fed to the bottom of an absorption column (C1) which is supplied at the top and in counter-current by at least one heavy hydrophobic absorption solvent for obtaining, at the bottom of the column (C1), a flow (4) constituted of (meth)acrylic acid, the absorption heavy solvent(s), the heavy secondary reaction products and minor amounts of acetic acid and of water (with acrylic acid during the production of methacrylic acid), and; the flow (4) coming from column (C1) is then fed to a separation column (C2). Column (C1) is operated with a flow rate of the heavy solvent being 3 to 5.6 times that of the (meth)acrylic acid in the supply gas mixture, and a rectifying column is used as a separation column (C2) operated with a supply at the top and without reflux.