Abstract: Process for preparing piperazine of the formula I by reacting diethanolamine (DEOA) of the formula II with ammonia (NH3) in the presence of hydrogen and a supported, metal-containing catalyst, wherein the catalytically active mass of the catalyst, prior to its reduction with hydrogen, comprises 20 to 85% by weight of oxygen-containing compounds of zirconium, calculated as ZrO2, 1 to 30% by weight of oxygen-containing compounds of copper, calculated as CuO, 14 to 70% by weight of oxygen-containing compounds of nickel, calculated as NiO, and 0 to 5% by weight of oxygen-containing compounds of molybdenum, calculated as MoO3, and the reaction is carried out in the liquid phase at an absolute pressure in the range from 160 to 220 bar, a temperature in the range from 180 to 220° C., using ammonia in a molar ratio to DEOA used of from 5 to 20 and in the presence of 0.2 to 9.0% by weight of hydrogen, based on the total amount of DEOA used and ammonia.

Abstract: The present invention relates to a process for improving the color stability by postpurifying piperazine, the steps comprising preparing an aqueous piperazine solution by introducing solid or liquid piperazine having a degree of purity of at least 90% by weight in water; removing the water by distillation; isolating the piperazine with a predefined maximum residual content of water. The invention further provides a rapid test of aging for checking the improvement in the color stability.

Abstract: A fabric packing has a plurality of layers made of a filament of metal or plastic and includes bulges for maintaining the fabric layers at a distance. The bulges have first protuberances of generally trough-shaped configuration and second protuberances formed on the first protuberances, thereby defining respective apexes. The second protuberances are sized smaller than the first protuberances, wherein neighboring fabric layers are supported on one another via the second protuberances.