公开(公告)号：DE3138419A1

公开(公告)日：1983-04-14

申请号：DE3138419

申请日：1981-09-26

Applicant: BASF AG

Inventor： FROMM DIETER DIPL CHEM DR ,  SCHIER ERNST-JUERGEN DIPL CHEM ,  SCHNEEHAGE HANS HENNING DIPL C ,  VODRAZKA WOLFGANG DIPL CHEM DR

IPC: B01J21/20 ,  B01J38/06 ,  C07B61/00 ,  C07D251/60 ,  C07D251/62

Abstract: In the synthesis of melamine by conversion of urea in a fluidized catalyst bed, the melamine quality is improved by reactivating the catalyst by treating it, in the fluidized bed, with gases containing steam, in the absence of oxygen, at from 250 DEG to 450 DEG C.

公开(公告)号：DE3031124A1

公开(公告)日：1982-04-08

申请号：DE3031124

申请日：1980-08-18

Applicant: BASF AG

Inventor： BORHO KLAUS DIPL ING DR ,  FROMM DIETER DIPL CHEM DR ,  SCHIER ERNST-JUERGEN DIPL CHEM ,  SCHNEEHAGE HANS HENNING DIPL C ,  WIDMANN ALFRED DIPL ING DR

IPC: C07C273/10 ,  C07C67/00 ,  C07C239/00 ,  C07C273/12 ,  C07C273/16 ,  C07D251/62 ,  C07D251/60

Abstract: A process for isolating liquid urea and its thermal decomposition products from the off-gas of melamine synthesis, which gas has been freed from melamine by fractional condensation and then been washed with molten urea, wherein the off-gas, containing 2-10 kg of melt per kg of pure gas, is passed at 8-30 m/sec tangentially into the upper part of an axially symmetrical separation zone. As a result of the rotation imparted to the gas/liquid mixture, the two phases are separated from one another, and both pass downward through the separation zone. The gas and liquid are separately taken off at the bottom end of the separation zone. The residence time of the gas mixture in the separation zone is not less than 0.5 second.