METHOD AND APPARATUS FOR PURIFYING ACRYLIC ACID Russian patent published in 2020 - IPC C07C51/43 C07C57/04 B01D9/00 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of purifying a crude acrylic acid composition containing maleic anhydride as an impurity, the method comprising the following steps: (a) performing at least one stage (14, 14a, 14b, 14c, 14d) of dynamic crystallisation from the melt with a crude acrylic acid composition to obtain a first composition of purified acrylic acid and a first residue containing at least 3.5 wt. % maleic anhydride, (b) adding solvent (26) which is capable of dissolving maleic anhydride, to a first residue in an amount such that the weight ratio of the solvent to malein anhydride is 0.3 or more to obtain a residue-adjusted, and (c) conducting at least one additional dynamic crystallisation step from the melt and/or at least one static crystallisation stage (18, 18a, 18b) from the melt with a residue adjusted to obtain a second composition of purified acrylic acid and a second residue, wherein weight ratio of solvent to malein anhydride in step (b) is controlled by value in range from 0.3 to 2.0.

EFFECT: disclosed is a method and apparatus for purifying acrylic acid.

11 cl, 2 dwg, 1 tbl, 2 ex