Methanol recovery from methyl acetate-methanol mixtures in methanolysi - s of polyvinyl acetate

摘要

The crude solvent mixture is introduced to a predistillation plate-type column heated by direct injection of steam. Methanol and methyl acetate are separated in the vapour phase while the non-distillable constituents are removed with the water of condensation. The obtained methanol-methyl acetate mixture is rectified in order to separate a first methanol fraction from the methyl acetate-methanol azeotropic mixture. This azeotropic mixture is subjected to a hydro-selective treatment in order to regain methyl acetate and aqs. methanol, and the latter rectified in order to separate methanol. Heat energy is saved; an anhydridrous methyl acetate-methanol mixture suitable for washing polyvinyl alcohol is obtained after the first step.