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Process for production of diaryl carbonate

a diaryl carbonate and production process technology, applied in the direction of carbonic/haloformic acid esters purification/separation, chlorine/hydrogen-chloride, phosgene or haloformate preparation, etc., can solve the problems of complex purification operation, inability to carry out the process economically, and high cost of the process

Inactive Publication Date: 2009-07-09
BAYER MATERIALSCIENCE AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in these known processes, a high residual phenol value in the wastewater of these processes, which can pollute the environment and give the effluent treatment plants increased wastewater problems, makes complex purification operations necessary.
A disadvantage of ozonolysis is that this process is very cost intensive.
A disadvantage of the process is that the water must be completely evaporated so that the process cannot be carried out economically.
However, by means of the process described, only a maximum of 26% of the sodium chloride can be recovered from the wastewater of the DPC production, since, at higher feed rates, the water introduced into the electrolysis together with the wastewater would bring the water balance of the sodium chloride electrolysis out of equilibrium.
It is not possible thereby to recover all of the alkali metal chloride present in the solutions in this manner.
However, the evaporation is energy intensive and expensive.

Method used

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  • Process for production of diaryl carbonate
  • Process for production of diaryl carbonate
  • Process for production of diaryl carbonate

Examples

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example 1

Addition of Enriched Sodium-Chloride-Containing Reaction Wastewater to the Sodium Chloride Electrolysis—Addition of a 22.5% Strength by Weight Sodium Chloride Solution from the DPC Production to the Sodium Chloride Electrolysis

[0111]a) Isolation of the Production Wastewater from DPC Production

[0112]In a vertically upright cooled tubular reactor, a mixture of 145.2 kg / h of 14.5% strength sodium hydroxide solution produced by diluting 65.8 kg / h of a 32% strength sodium hydroxide solution with 79.4 kg / h of demineralized water, and 48.3 kg / h of phenol was continuously combined with a solution of 86.2 kg / h of methylene chloride and 27.5 kg / h of phosgene (8 mol % excess based on phenol). This reaction mixture was cooled to a temperature of 33° C. and after a median residence time of 15 seconds, a pH of 11.5 was measured. Then, in the second stage of the process, to this reaction mixture was added 5.4 kg / h of 50% strength NaOH, so that the pH of the second reaction stage, after a further r...

example 2

Addition of Enriched Sodium-Chloride-Containing Production Wastewater to the Sodium Chloride Electrolysis—Addition of an 18.0% Strength by Weight Sodium Chloride Solution from the DPC Production to the Sodium Chloride Electrolysis

a) Sodium Chloride Enrichment of Production Wastewater by Wastewater Recycling to the Production Process

[0119]The procedure was followed as described in Example 1b) but the reaction wastewater was combined with the wash phases and subsequently freed from solvent residues and catalyst by stripping with steam. After neutralization with hydrochloric acid and treatment with activated carbon, the production wastewater contained 18.0% by weight NaCl and less than 2 ppm of organic impurities.

[0120]It could be fed without further purification to the electrochemical oxidation to chlorine.

b) Electrochemical Oxidation of the Enriched Production of Wastewater from a)

[0121]The electrolysis was carried out by way of example in a laboratory electrolysis cell having an ano...

example 3

Addition of Enriched Sodium-Chloride-Containing Reaction Wastewater to the Sodium Chloride Electrolysis—Addition of a 22.3% Strength by Weight Sodium Chloride Solution from DPC Production to the Sodium Chloride Electrolysis

a) Sodium Chloride Enrichment of Reaction Wastewater by Elevation of the Sodium Phenolate Concentration in the DPC Production

[0124]The procedure was followed as described in example 1a), but instead of 79.4 kg / h, only 54.6 kg / h of demineralized water was used. After separating off the organic phase from the aqueous phase (reaction wastewater), the organic phase was washed with 0.6% strength hydrochloric acid and water. After removal of the solvent, 99.9% pure diphenyl carbonate was obtained. The reaction wastewater, without prior combination with the wash phases, was freed from solvent residues and catalyst by stripping with steam. After neutralization with hydrochloric acid and treatment with activated carbon, the reaction wastewater contained 22.3% by weight NaC...

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Abstract

The invention relates to a process for production of diaryl carbonate combined with the electrolysis of the resultant alkali metal chloride-containing process wastewater. The process according to the invention makes possible, inter alia, improved utilization in electrolysis of the alkali metal chloride-containing solution obtained in the production of diaryl carbonate.

Description

RELATED APPLICATIONS[0001]This application claims benefit to German Patent Application No. 10 2007 05 8 701.7, filed Dec. 12, 2007, which is incorporated herein by reference in its entirety for all useful purposes.BACKGROUND OF THE INVENTION[0002]The invention relates to a process for production of diaryl carbonate combined with the electrolysis of the resultant alkali metal chloride-containing process wastewater. The process according to the invention makes possible, inter alia, improved utilization in electrolysis of the alkali metal chloride-containing solution obtained in the production of diaryl carbonate.[0003]The production of diaryl carbonates (diaryl carbonate) proceeds conventionally by a continuous process, by production of phosgene and subsequent reaction of monophenols and phosgene in an inert solvent in the presence of alkali and a basic nitrogen catalyst in the interface.[0004]The production of diaryl carbonates, for example by the phase boundary process, is described...

Claims

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Application Information

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IPC IPC(8): C25B3/02C01B32/80C25B3/23
CPCC01B7/03C01D3/04C07C68/02C25B1/34C07C69/96C25B1/46C25B15/08C01B32/80C01D3/06C07C68/08
Inventor OOMS, PIETERBULAN, ANDREASRECHNER, JOHANNWEBER, RAINERBUTS, MARCVANDEN EYNDE, JOHAN
Owner BAYER MATERIALSCIENCE AG
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