Fremgangsmåde til oprensning af acrylsyre, der er opnået ved katalytisk oxidation af propylen

摘要

A process for the purificn. of acrylic acid obtd. by catalytic oxidn. of propylene extracted by counter-current washing of the reaction gases with a heavy hydrophobic solvent in an extn. column (C1) comprises directing the distn. flow (5) from the base of column (C1) to column (C3), and contg. the heavy extn. solvent(s), acrylic acid and impurities (mainly of b.pt. greater than that of acrylic acid), the distn. being effected in conditions such that a very pure flow of acrylic acid (6) is obtd. from the head of C3, whilst allowing some acrylic acid to pass from the base (7); feeding the effluent (7) to the lower part of a distn. column (C4) from which a lateral withdrawal at a plate between the supply and the column head is taken (9), which is rich in maleic anhydride and impurities of b.pt. between acrylic acid and the heavy solvent(s); distilling a flow (8) rich in acrylic acid from the head of (C4); and recovering a flux (1) from the base of (C4) contg. the heavy extn. solvent(s) and heavy impurities , and recycling to the head of (C1).