Patent ID: 6642414
Filing Date: 2003-11-04
Classification: C07C

Abstract:
A method for producing (meth)acrylic acid, which comprising:(a) a step of obtaining a gaseous reaction product containing (meth)acrylic acid by subjecting at least one member selected from the group consisting of propylene, propane, acrolein, and a mixture thereof or at least one member selected from the group consisting of isobutylene, t-butyl alcohol, methyl-t-butyl ether, methacrolein, and a mixture thereof to the reaction of catalytic gas phase oxidation; (b) a step of absorbing the gaseous reaction product by the use of a solvent; (c) a step of separating said solvent, a low boiling impurity, and a high boiling impurity from the (meth)acrylic acid solution absorbed with said solvent by extraction and/or distillation and obtaining crude (meth)acrylic acid solution containing aldehydes having boiling points approximating closely to the boiling point of(meth) acrylic acid as impurities; (d) a step of adding an aldehyde treating agent to said crude (meth)acrylic acid and subjecting the resultant mixture to vacuum distillation thereby obtaining (meth)acrylic acid of high purity; and (e) a step of returning the waste liquid generated in said step (d) to said step (b) and/or said step (c).