PURPOSE: To recover acetic acid in a simplified step and saved energy, by reacting an aqueous solution, containing an acetate, and formed in a process for preparing polyvinyl alcohol as a by-product with a mineral acid and methanol, and hydrolyzing the resultant distillate simultaneously with a remaining solution of the same composition.
CONSTITUTION: A remaining solution obtained after separating polyvinyl alcohol from a reaction mixture solution obtained by the ester interchange of polyvinyl acetate with methanol contains methyl acetate mainly and the unreacted methanol and an acetate. In recovering the acetic acid from the aqueous solution containing the acetate, the aqueous solution is introduced into a reactor having a distillation column and reacted with methanol in an amount excess of the acetate to distill the methyl acetate and methanol from the top of the column, hydrolyze the distillate simultaneously with the remaining solution separated by the above-mentioned ester interchange and recover the acetic acid.
EFFECT: The recovery can be carried out even in a low concentration.
FUCHIGAMI YOSHIO
KIKUCHI KOUICHI
