| abstract |
Method for preparing piperazine of formula I by reacting diethanolamine (DEOA) of formula II with ammonia in the presence of hydrogen and a metal-containing supported catalyst. Before the catalyst is reduced with hydrogen, the catalytically active mass of the catalyst contains oxygen-containing aluminum, copper, nickel and cobalt compounds and 0.2 to 5.0 wt.% oxygen-containing tin compounds calculated as SnO, and the reaction is carried out in the liquid phase at an absolute pressure ranging from 160 to 220 bar, at a temperature ranging from 180 to 220°C, ammonia is used at a molar ratio ranging from 5 to 25 in relation to the DEOA used in the process, the method being carried out in the presence of 0.2 to 9.0 wt.% hydrogen relative to the total amount of DEOA and ammonia used in the process. |