DD139528A1 - DESALINATION OF ORGANIC FLUIDS - Google Patents

Abstract

Process for removal and recovery of the metallic Proportion of catalyst residues or -Umsetzungsprodukten synthesized liquids. The goal is a continuous one Design of the removal of impurities and avoidance from manual work. This is done by electrolysis of the liquids and recovering and recycling the metal components.

Description

20370 9

Title of the invention

Desalination of organic liquids

Field of application of the invention

The invention relates to a process for the continuous removal, regeneration and recycling of catalyst residues or reaction products from synthetically produced liquids.

Characteristic of the known technical solutions

Some organic syntheses use alkali metals or their compounds as catalyst. The metal compounds are contained in the product leaving the synthesis stage and must be removed therefrom. At the same time, the discharged catalyst must be replaced by new ones. As an example, the synthesis of dimethylformamide according to the single-stage process will be mentioned. In this process, sodium hydroxide is introduced into the reactor as a catalyst.

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The resulting sodium compounds are contained in the crude synthesis product and are precipitated in a pre-distillation blister, predominantly in the form of sodium formate, as sludge or crusts. The regularly necessary cleaning of this bubble is associated with closure of pre - distillation, manual labor under difficult conditions and seizure of sodium formate wastewater.

An improvement of this known procedure is achieved if special evaporation equipment used (DD-PS 123312) or a method for the mechanical separation of salt crystals applied (DD-PS 114804). However, such known processes produce a solid salt and require the laborious operations of separating the pesticides from the remaining mother liquor and transporting the pesticide. The resulting solid represents chemically converted catalyst, for the synthesis process is therefore constantly fresh catalyst to use, which in addition to the costs incurred catalyst costs further expenses for transport and mixing requires.

Object of the invention

The aim of the invention is to make the salt removal continuously, without mechanical or manual work and to ensure a catalyst circulation and thus to achieve a reduction in the use of material and working time and an improvement in working conditions and a reduction in environmental impact.

Statement of the invention

The object of the invention is to develop a process for desalination. ,

This object is achieved according to the invention in that a synthetically produced organic liquid which contains less than 10 % of water, catalyst residues and reaction products is subjected to electrolysis. Here are the

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Metal components of the impurities deposited on a moving mercury cathode. The mercury loaded with the metal is treated with a liquid, preferably methanol, and the metal is taken up by this. The loaded liquid or the metal component recovered from it is returned to the production plant.

The method is based on the use of an electrolytic cell and a decomposer, which are constructed similar to those used in the chloralkali electrolysis according to the known amalgam method. The essential difference from the known amalgam method, however, consists in the liquids used. , The process principle is described below in the example of the preparation of dimethylformamide by the one-step process (see FIG.

embodiment

The discharged from the reactor part relaxed crude product consists essentially of dimethylformamide and methanol and contains the reacted catalyst in the form of sodium formate.

The crude product enters the predistillation bubble 2 through line 1. The distillation vapors reach by means of line in the downstream distillation part. From the bubble 2, liquid is constantly withdrawn by means of the pump β. The liquid temperature can be adjusted by means of the heat transfer apparatuses 4 and 5. The liquid enters the electrolytic cell 7, in which, depending on the set operating conditions, most of the sodium contained is deposited on a flowing mercury cathode. The thus largely desalted liquid flows back into the bladder 2 via the heat transfer apparatus 4. The sodium-loaded mercury is conveyed by means of pump 8 into the decomposer 9. Through the decomposer, methanol flows through line 10 which has been separated from the vapors 4-line 3 in the distillation part and effects by formation

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of sodium methylate removal of sodium from mercury. The methanol with the dissolved sodium methylate is conveyed through line 11 back to the reactor part. This realizes the recycling of the catalyst.

Claims (1)

20070 9 -5- invention claim A method of removing and recovering the metallic portion of a contaminant from a liquid, characterized in that the synthetic organic liquid containing less than 10 % of water and contaminated by catalyst residues or reaction products is subjected to electrolysis, the metal components of the contaminants are deposited on a moving mercury cathode and the mercury laden with the metal is treated with another liquid, preferably methanol, which receives the metal, and the liquid. Or the recovered from their metal component in the production plant, preferably in the synthesis part, is recycled , For this 1 sheet drawing ·