C(O)(=O)/C=C\C(O)=O.[C:9]([OH:20])(=[O:19])[C:10]1[C:11](=[CH:15][CH:16]=[CH:17][CH:18]=1)[C:12]([OH:14])=O.C(O)(=O)/C(=C\C(O)=O)/C.C(O)(=O)C1C=CC=CC=1>CC1C=CC=CC=1C>[C:12]1(=[O:14])[O:20][C:9](=[O:19])[C:10]2=[CH:18][CH:17]=[CH:16][CH:15]=[C:11]123200 parts of a 22% solution of maleic acid which contains 4% of other acids such as phthalic acid, citraconic acid and benzoic acid is supplied per hour through a tubular heater which preheats to 100°C to a falling-film evaporator. This solution has been obtained by scrubbing offgas obtained in the manufacture of phthalic anhydride by catalytic oxidation of o-xylene with air at a temperature of 40°C. In the first evaporator the solution is concentrated at atmospheric pressure and at 120°C to a content of 40% of maleic acid. The aqueous condensate is returned to the offgas scrubber.
Wird geladen…
