Method for purifying (meth)acrylic acid

A process for the purification of (meth)acrylic acid in an absence of organic solvent and in an absence of a chemical treatment of aldehydes, from a gaseous reaction mixture comprising (meth)acrylic acid obtained by gas-phase oxidation of a precursor of (meth)acrylic acid, said process comprising the following stages:

• subjecting said reaction mixture to a dehydration, without using azeotropic solvent, in a dehydration column, resulting in a top stream and a bottom stream being obtained,
• sending at least a portion of said bottom stream from the dehydration column into an upper part of a finishing column, where light products are distilled, heavy products are removed at a bottom of the finishing column and a side stream is withdrawn,
• sending said side stream from the finishing column to a lower third of a third distillation column, resulting in a top stream, a side stream and a bottom stream being obtained, said top stream being subjected to a condensation and then returned after condensation, partly in the third distillation column in reflux form and partly being recovered, said side stream being withdrawn in a half of a lower part of said third distillation column.