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.
Abstract:
Process for recovering cyclododecatriene (CDT) from a solution comprising CDT and high boilers such as deactivated catalyst and polymers, which comprises feeding the solution into a preheater and heating it, subsequently depressurizing it through a downstream pressure maintenance device and feeding the resulting two-phase mixture into a helical tube evaporator and there reducing the CDT content of the liquid phase by partial evaporation and discharging a gaseous product stream having an increased concentration of CDT.
Abstract:
Pure triethylenediamine (TEDA) is prepared by vaporizing TEDA, introducing the gaseous TEDA into a liquid solvent and subsequently crystallizing the TEDA from the solution obtained in this way.
Abstract:
Process for recovering cyclododecatriene (CDT) from a solution containing CDT and high boilers such as deactivated catalyst and polymers, which includes feeding the solution into a preheater and heating it, subsequently depressurizing it through a downstream pressure maintenance device and feeding the resulting two-phase mixture into a helical tube evaporator and there reducing the CDT content of the liquid phase by partial evaporation and discharging a gaseous product stream having an increased concentration of CDT.
Abstract:
A process for preparing a high-concentration formaldehyde solution by removing water from a lower-concentration formaldehyde solution having a formaldehyde content of from 5 to 50% by weight, in which the lower-concentration formaldehyde solution is fed to a preheater and heated in the preheater, depressurized via a pressure maintenance device and concentrated in a helical tube evaporator to give a vapor stream and the high-concentration formaldehyde solution as bottom stream, wherein the heated lower-concentration formaldehyde hyde solution is depressurized in the pressure maintenance device to give a two-phase mixture which is fed into the helical tube evaporator, is proposed.
Abstract:
Highly pure triethylenediamine is obtained by a process in which triethylenediamine is freed from high boilers and then the triethylenediamine is vaporized from the mixture thus obtained and is passed into a liquid solvent. The process makes it possible in particular to obtain highly pure solutions of triethylenediamine. Crystallization is generally unnecessary.
Abstract:
Process for preparing a solution of pure triethylenediamine (TEDA), in which TEDA is vaporized, the gaseous TEDA is passed into a liquid solvent 1 (quench) and the TEDA is crystallized from the resulting solution and separated off (solid-liquid separation), wherein the crystalline TEDA obtained is dissolved in a solvent 2 and a stripping gas is passed through the resulting solution (stripping).
Abstract:
The present invention relates to a process for working up triethylenediamine (TEDA) in which TEDA is vaporized and the gaseous TEDA is introduced into a solvent, subsequently crystallized and separated off from this and the mother liquor formed is extracted with an extractant, wherein the raffinate phase obtained after the extraction stage is worked up further by adsorption in which extractant and/or by-products and intermediates present in the raffinate phase are removed therefrom.
Abstract:
A process for preparing a high-concentration formaldehyde solution by removing water from a lower-concentration formaldehyde solution having a formaldehyde content of from 5 to 50% by weight, in which the lower-concentration formaldehyde solution is fed to a preheater and heated in the preheater, depressurized via a pressure maintenance device and concentrated in a helical tube evaporator to give a vapor stream and the high-concentration formaldehyde solution as bottom stream, wherein the heated lower-concentration formaldehyde hyde solution is depressurized in the pressure maintenance device to give a two-phase mixture which is fed into the helical tube evaporator, is proposed.
Abstract:
Process for preparing a solution of pure triethylenediamine (TEDA), in which TEDA is vaporized, the gaseous TEDA is passed into a liquid solvent 1 (quench) and the TEDA is crystallized from the resulting solution and separated off (solid-liquid separation), wherein the crystalline TEDA obtained is dissolved in a solvent 2 and a stripping gas is passed through the resulting solution (stripping).