Patent ID: 6888026
Filing Date: 2005-05-03
Classification: C07C

Abstract:
1. A method for producing (meth)acrylic acid comprising the steps of obtaining a mixed gas containing (meth)acrylic acid and glyoxal by catalytic gas phase oxidation using propylene and/or acrolein, or using at least one compound selected from the group consisting of isobutylene, t-butyl alcohol, and methacrolein, contacting the mixed gas with a collecting liquid to obtain a (meth)acrylic acid aqueous solution, separating the (meth)acrylic acid aqueous solution into (meth)acrylic acid and a discharged liquid containing glyoxal by distillation, separating a part or all of the discharged liquid into a permeated liquid and an impermeated liquid containing glyoxal with the use of reverse osmosis membrane, thereby reducing a concentration of glyoxal contained in the permeated liquid, and recycling a part or all of the permeated liquid by circulation as the collecting liquid.