Purification of acrylic acid, used as acid, salt or ester in polymer production, involves cooling crude melt in presence of water and washing crystal suspension with purified crystal melt in column with forced transport of crystals

摘要

Purifying crude acrylic acid melt by converting to a crude acrylic acid suspension by cooling, and separating from remaining residual melt in wash column. In purifying a crude melt of acrylic acid (I) containing (excluding water) /- 80 wt.% (I), /- 100 ppm weight acetic acid and /- 10 ppm weight propionic acid, a suspension of purer (I) crystals (IA) and less pure residual melt (II) is produced by cooling the crude melt in the presence of 0.20- 10 wt.% water with respect to (I); and, after optional mechanical separation of part of (II), (IA) are freed from (II) in a column operating with forced transport of (IA) by washing with a melt of purified (IA).