In the production of poly vinyl alc

In the production of poly vinyl alcohol (PVOH), the resultant methyl acetate formed is considered a mother 20 liquor to be ultimately purified and fed to a methanol carbonylation reactor fbr the production of acetic acid. The crude methyl acetate mixture is directed to a mother liquor column fbr purification to remove impurities such as light organic components, polymeric solids and water. The col- 25 umn is operated at elevated pressure, and heated, to remove essentially all of the methyl acetate in an overhead stream in purified form, and over 95% of the methanol from the impure methyl acetate crude mixture. The reflux of the column is adjusted to maintain about one mole of water fbr 30 every mole of methyl acetate in the column overhead. The polymeric solids typically consist of poly vinyl acetate, poly vinyl alcohol, and sodium acetate and exit from the bottom of the mother liquor column as a residue.