公开(公告)号：DE59707380D1

公开(公告)日：2002-07-11

申请号：DE59707380

申请日：1997-02-20

Applicant: BASF AG

Inventor： MACHHAMMER DR ,  DAMS DR ,  ECK BERND ,  PROLL DR

IPC: C07C57/04 ,  C07C51/43 ,  C07C57/05 ,  C07C57/07

Abstract: A process for purifying (meth)acrylic acid by phase separation techniques comprises the following steps: (a) a mixture containing (meth)acrylic acid is separated into distinct phases in the presence of an organic solvent, with the composition of the (meth)acrylic acid-rich phase remaining essentially unchanged, and this acid-rich phase is separated; (b) the remaining phase from step (a) is separated into indistinct phases; and (c) one of the phases from step (b) is returned to step (a). Also claimed is preparation of (meth)acrylic acid. Preferably in step (c) the acid-rich phase is returned to step (a). 1-100 (100) wt.% of the phase remaining from step (a) is used in step (b). Pure end product is added to steps (a) and (b). Step (a) involves crystallisation, freezing or sublimation, preferably static and/or dynamic crystallisation, and most preferably a combined static and dynamic crystallisation in which the residue from the dynamic crystallisation is added to the static crystallisation step and the crystallised product from the static crystallisation is returned to the dynamic crystallisation.