Patent ID: 6352619
Filing Date: 2002-03-05
Classification: C07C,Y10S

Abstract:
In a distillation process for purifying acrylic acid contaminated with aldehyde impurities wherein polymeric impurities are formed during a step for removing the aldehyde impurities from a medium containing acrylic acid, the improvement comprising conducting the distillation of the medium containing the acrylic acid to be purified in at least one distillation column in the presence of at least one nonionic surfactant and of at least one polymerization inhibitor, said at least one nonionic surfactant being selected from the group consisting of:compounds represented by formula (I): â€ƒin which: the groups R1 independently represent H; a C1-C4 alkyl group; CH3COâ€”; â€ƒwith R2=H, CH3 or C2H5; m=integer from 1 to 20 and R3=H or C1-C4 alkyl or CH3COâ€”; and n is an integer greater than 1, representing the number of chain units in a polymer chain; ethylene glycol and propylene glycol derivatives or ethers thereof, represented by formula (II): â€ƒin which: R4 and R5 each independently represent HOâ€” or R7Oâ€” or R7â€”C6H4Oâ€” with R7 representing a C1-C20 alkyl group; R6 represents H or CH3; and p is an integer from 3 to 20; glycol ester derivatives, represented by the formula (III): â€ƒin which: R8 represents a C8-C20 alkyl group; R9 represents H or a C8-C20 alkyl group; R10 represents H or CH3; q is an integer from 1 to 20; glyceryl ester derivatives, represented by formula (IV) â€ƒin which: R11 represents a C8-C20 alkyl group; and R12 represents H or â€ƒR13 representing a C8-C20 alkyl group; carboxylic amide derivatives, represented by formula (V): â€ƒin which: R14 represents a C8-C20 alkyl group; R15 represents H or â€ƒwith R19 representing H or CH3 and y being an integer from 1 to 5; R16 represents H or â€ƒin which R20 represents H or â€ƒwith R22 representing H or CH3 and z is an integer from 1 to 5, and R21 is a C8-C20 alkyl; R17 and R18 each independently represent H or CH3; r being equal to 0 or being an integer from 1 to 20; and s being equal to 0 or 1.