Process for isolating acrylic acid from aqueous crude acrylic acid by extraction with a ketone and plural stage distillation

Abstract

Abstract Pure acrylic acid is isolated from an aqueous crude acid containing acrylic acid together with minor proportions of acetic acid, formaldehyde and high boilers boiling at a temperature higher than 220*C by liquid-liquid extraction with the use of 3,3,5-trimethylcyclohexanone and/or isophorone as the extractant(s). To this end, the aqueous acrylic acid-containing crude acid is subjected in an extraction zone to counterflow extraction with the use of the extractant(s) and with the resultant formation of an organic extract containing acrylic acid, acetic acid, high boilers and minor proportions of water, which are dissolved in the extractant; the extract is introduced approximately into the midsection of a first distilling column, which is operated under reduced pressure; the base product of said first distilling column, containing the high boilers and the extractant(s) is recycled to the extraction zone; distillate containing acrylic acid, acetic acid, water and minor proportions of extractant(s) is delivered approximately to the midsection of a second distilling column, which is operated under reduced pressure; a mixture of water and extractant(s) is distilled off; the base product of said second distilling column, containing acrylic acid and acetic acid is introduced into a third distilling column, which is operated under reduced pressure; and acetic acid is separated therein as a distillate and acrylic acid is separated therein as the base product.

Inventors

• 👤 Kurt Sennewald
• 👤 Heinz Erpenbach
• 👤 Heinz Handte
• 👤 Winfried Lork

Bibliographic Details