摘要:
Maleic anhydride is recovered by evaporating the effluent from the production of phthalic anhydride at from 40.degree. to 150.degree.C and from 50 to 760 mm to a water content of less than 10% by weight, heating the concentrate in a thin-film or falling-film evaporator at from 100 to 600 mm at from 120.degree. to 180.degree.C and distilling it in a column. The pure maleic anhydride is withdrawn laterally and the aqueous condensate is recycled to the offgas scrubber.