Patent ID: 7342130

Claim:
A method for producing acrylic acid, comprising (a) an absorption step of absorbing an acrylic acid-containing gas obtained by oxidizing a raw material gas in gas phase as a crude acrylic acid-containing solution; (b 1 ) a high boiling point component separation step of separating high boiling point components at a distillation column as (b) a step of purifying the crude acrylic acid-containing solution; (c) a decomposition step of decomposing Michael adducts contained in the high boiling point components to generate acrylic acid; and (d) a collection step of collecting the acrylic acid generated in the decomposition step (c), wherein a column bottom of the distillation column at the high boiling point component separation step (b 1 ) has a temperature of 90 to 130° C., a residence time of a column bottom solution is 2 to 30 hours, and a ratio of a mass of solution fed to the distillation column to a mass of extraction solution from the column bottom of the distillation column is 5 to 20, and a proportion of an amount of maleic acid to a sum of maleic acid and maleic anhydride in the high boiling point components fed from the high boiling point component separation step (b 1 ) to the decomposition step (c) satisfies equation (1) below: [ Maleic ⁢ ⁢ acid ⁢ ⁢ ( mass ) ] [ Maleic ⁢ ⁢ acid ⁢ ⁢ ( mass ) ] + [ Maleic ⁢ ⁢ anhydride ⁢ ⁢ ( mass ) ] × 100 ≦ 70 ⁢ % . ( 1 )