To provide a method for purifying a vinyl-type monomer by which a waste liquid generated at the time of purification of the vinyl-type monomer is reduced, and thereby the load of waste-liquid treatment is reduced by bringing the vinyl-type monomer containing a mercaptan-based compound into contact with an oxide catalyst in the presence of molecular oxygen in a gas phase.
A vinyl-type monomer containing a mercaptan-based compound (e.g. n methylmercaptan) is brought into contact with an oxide catalyst in the presence of molecular oxygen (e.g. air) in a gas phase. The catalyst is preferably the oxide catalyst of the formula, XaSibAlcOd [X is copper; (a) to (d) are each an atomic ratio of each element, and when (a) is 1, (b) is 0-50, (c) is 0-50 and (d) is an atomic ratio of oxygen required for satisfying atomic valence of each component]. The vinyl-type monomer and the catalyst are usually brought into contact at 100-200°C under a pressure from a reduced pressure of several ten kPa to a pressurized pressure of several hundred kPa preferably for 0.1-10 sec. The amount of the supplied molecular oxygen is preferably 0.01-0.5 time as much as that of the monomer.
YANAGII MASAHARU
SHIN JUNICHIRO
SATO HARUMOTO
OKUTSU HAJIME
OKITA MOTOMU
