公开(公告)号：BR9811781A

公开(公告)日：2000-09-12

申请号：BR9811781

申请日：1998-09-09

Applicant: BASF AG

Inventor： ECK BERND ,  MACHHAMMER OTTO ,  PROLL THO ,  SCHLIEPHAKE VOLKER ,  THIEL JOACHIM ,  BRUELLOS KLAUS

IPC: C07C51/43 ,  C07C51/44 ,  C07C57/07

Abstract: A process for preparing acrylic acid or methacrylic acid comprises preparing a gaseous product mixture having essentially the composition of a reaction mixture of the catalytic gas phase oxidation of C3-/C4-alkanes, -alkenes, -alkanols and/or -alkanals and/or precursors thereof to form acrylic acid or methacrylic acid. The product is removed from the gaseous product mixture by a process comprising the following steps:(a) condensing said gaseous product mixture,(b) crystallizing acrylic acid or methacrylic acid from the solution obtained in step (a),(c) removing the resulting crystals from the mother liquor, and(d) recycling at least a portion of said mother liquor from step (c) into step (a).