Abstract: Process for preparing piperazine of the formula I by reacting diethanolamine (DEOA) of the formula II with ammonia in the presence of hydrogen and a supported, metal-containing catalyst has been found, wherein the catalytically active mass of the catalyst, prior to its reduction with hydrogen, comprises oxygen-containing compounds of aluminum, copper, nickel and cobalt and in the range from 0.2 to 5.0% by weight of oxygen-containing compounds of tin, calculated as SnO, 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 25 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 mixture of ethylenediamine (EDA) and N-methylethylenediamine (Me-EDA) with a low content of Me-EDA, which comprises at least 99.5% by weight of ethylenediamine, and wherein the concentration of N-methylethylenediamine is in the range from 0.005 to 0.15% by weight. The present invention further relates to a process for distillative workup of a mixture comprising EDA, Me-EDA and water, by introducing the mixture into a distillation column which is operated at a column top pressure of 10 mbar to 4 bar, wherein the weight ratio of water to ethylenediamine in the mixture used is a*X:Y where X is the proportion by weight of water and Y is the proportion by weight of ethylenediamine at the azeotropic point of a binary mixture of water and ethylenediamine at the column top pressure in question, and a is a real number with a value of 0.9 or more.

Abstract: Process for preparing piperazine of the formula I by reacting diethanolamine (DEOA) of the formula II with ammonia in the presence of hydrogen and a supported, metal-containing catalyst has been found, wherein the catalytically active mass of the catalyst, prior to its reduction with hydrogen, comprises oxygen-containing compounds of aluminum, copper, nickel and cobalt and in the range from 0.2 to 5.0% by weight of oxygen-containing compounds of tin, calculated as SnO, 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 25 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 mixture of ethylenediamine (EDA) and N-methyl-ethylenediamine (Me-EDA) with a low content of Me-EDA, which comprises at least 99.5% by weight of ethylenediamine, and wherein the concentration of N-methylethylenediamine is in the range from 0.005 to 0.15% by weight. The present invention further relates to a process for distillative workup of a mixture comprising EDA, Me-EDA and water, by introducing the mixture into a distillation column which is operated at a column top pressure of 10 mbar to 4 bar, wherein the weight ratio of water to ethylenediamine in the mixture used is a*X:Y where X is the proportion by weight of water and Y is the proportion by weight of ethylenediamine at the azeotropic point of a binary mixture of water and ethylenediamine at the column top pressure in question, and a is a real number with a value of 0.9 or more.

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.

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: The invention relates to a process for continuously, distillatively removing piperazine from an ethylenediamine-piperazine mixture under pressure at elevated temperature, by discharging the ethylenediamine at the top and the piperazine at the bottom of a distillation column. For the purpose of improving the quality of the piperazine, especially its color and color stability, the piperazine is subjected directly to circulation conveying it through an evaporator unit operated at a temperature of from about 160° C. to about 170° C. and returning it into the distillation column. After a residence time of from about 30 min to about 60 min in the circulation system, the piperazine is discharged in vapor form from a side draw in the lower section of the distillation column.