Patent ID: 7566804

Claim:
A process for preparing acrylic acid, comprising passing a product gas mixture comprising acrylic acid, steam and secondary components which is obtained by heterogeneously catalyzed gas phase partial oxidation of at least one C 3 precursor of acrylic acid with molecular oxygen over solid-state catalysts at elevated temperature, into a condensation column equipped with separating internals, allowed to ascend into itself within the condensation column and thus fractionally condensed, and crude acrylic acid comprising a reduced total amount of water and secondary components is conducted as the target product out of the condensation column via a first side draw disposed above the feed point of the product gas mixture into the condensation column, acid water still comprising acrylic acid and secondary components is conducted out of the condensation column via a second liquid phase draw disposed above the first side draw, and a portion of said acid water withdrawn is recycled as such and/or after cooling thereof as reflux liquid into the condensation column, a residual gas mixture comprising secondary components having lower boiling points than water is conducted out of the condensation column at the top of the condensation column, and a bottoms liquid still comprising acrylic acid and conversion products and secondary components having higher boiling points than acrylic acid is conducted out of the condensation column from the bottom space of the condensation column, wherein at least from a portion of acid water not recycled into the condensation column acrylic acid present in it is taken up from the acid water into an organic solvent by extraction with the organic solvent to form an organic extract comprising acrylic acid, then acrylic acid is removed from the organic extract by stripping with a first stripping gas and the resulting acrylic acid-laden first stripping gas is recycled into the condensation column and/or the acrylic acid present in the first laden stripping gas is taken up into the aqueous solution of a metal hydroxide, or is used as a second stripping gas in order to strip acrylic acid out of bottoms liquid conducted out of the condensation column, and the resulting acrylic acid-laden second stripping gas is recycled into the condensation column and/or the acrylic acid present in the second stripping gas is taken up into the aqueous solution of a metal hydroxide.