Patent ID: 6252110
Filing Date: 2001-06-26
Classification: B01D,C07C,Y10S

Abstract:
A method for recovering acrylic acid from high boiling impurities containing acrylic acid dimer, acrylic acid and maleic acid,wherein the high boiling impurities containing acrylic acid dimer, acrylic acid and maleic acid is a bottom liquid obtained from a high boiling impurities separation column used in the process comprising contacting an acrylic acid-containing gas resulting from gas-phase catalytic oxidation of propylene and/or acrolein with water to trap the acrylic acid in the form of an aqueous acrylic acid solution, distilling the aqueous solution in an azeotropic separation column in the presence of an azeotropic solvent, and purifying the resultant crude acrylic acid obtained from the bottom part of said azeotropic separation column in said high boiling impurities separation column,by a process which comprises(1) introducing said high boiling impurities containing acrylic acid dimer, acrylic acid and maleic acid, into an acrylic acid recovery column and recovering acrylic acid as it is distilled off from the top of the column,(2) introducing bottom liquid A from said acrylic acid recovery column into a pyrolyzing tank to decompose the acrylic acid dimer in the bottom liquid A, and then,(3) recirculating at least a part of bottom liquid B from said pyrolyzing tank into the acrylic acid recovery column.