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Method for preparing diaryl carbonates and polycarbonates

A technology of diaryl carbonate and diphenyl carbonate, which is applied in the field of preparing diaryl carbonate and polycarbonate, and can solve problems such as low current output

Active Publication Date: 2011-10-05
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage is the low current yield and the generation of hydrogen which is not useful in the polycarbonate production process

Method used

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  • Method for preparing diaryl carbonates and polycarbonates
  • Method for preparing diaryl carbonates and polycarbonates
  • Method for preparing diaryl carbonates and polycarbonates

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1a-h

[0204] Preparation of Diphenyl Carbonate by Direct Phosgenation of Phenol

[0205] 1a) In γ-Al 2 O 3 Preparation of diphenyl carbonate by phosgenation of phenol in the presence of

[0206] image 3 The apparatus used to carry out the method and the flows involved are schematically shown in .

[0207] 41.12 parts by weight / h of phenol 1 , fresh and / or recovered from the preparation of polycarbonate as described in example 3), were taken from heated vessel I and passed through heat exchanger III (60° C.) at Atmospheric pressure is fed from the top into a countercurrent packed column VII heated to 60° C., in which mixing with the phenol 14 withdrawn from the top of the distillation column X takes place. After the offgas stream 15 from the degassers VI and IX has passed through VII, the mixture 11 (phenol / phosgene weight ratio about 97 / 3) is fed in at the bottom. From this storage tank II, 21.93 parts by weight / h of phosgene 3 (170 °C) preheated by heat exchanger IV ...

Embodiment 2

[0240] Hydrogen chloride produced from diphenyl carbonate is recycled by electrochemical oxidation with oxygen

[0241] a) Electrochemical oxidation of hydrogen chloride using a gas diffusion electrode as an oxygen-consuming cathode

[0242] A stream of 8.16 parts by weight / h of purified hydrogen chloride from the diphenyl carbonate production was fed to the HCl absorption. For this purpose, a substream of the hydrochloric acid-depleted anolyte acid stream 28 from the electrolysis is passed into the hydrochloric acid 26 from the HCl absorption. 32.1 parts by weight / h of the anolyte acid 28 , which is depleted in hydrochloric acid and has an HCl concentration of 12.2 wt %, is fed into the HCl absorption. The HCl absorption unit produces hydrochloric acid 26 at a concentration of 30 wt%, which is combined with the remainder of the lean anolyte acid 28 and returned to the electrolytic cell. 2.96 parts by weight / h of the lean anolyte acid 28 was withdrawn from the anolyte acid...

Embodiment 3

[0246] Preparation of polycarbonate

[0247]From a storage tank, a molten mixture of 8600 parts by weight / h containing 4425 parts by weight / h of diphenyl carbonate prepared as described in 1a) or 1b) and 4175 parts by weight / h of bisphenol A (and Add 0.52 parts by weight / h of tetraphenylphosphorus Phenol adduct of phenate comprising 65.5% tetraphenylphosphine dissolved in 4.5 parts by weight / h of phenol / h phenate / h) is pumped through a heat exchanger, heated to 190°C and sent through a retention column at 12 bar and 190°C. The average residence time was 50 minutes.

[0248] The melt was then introduced via a pressure relief valve into a separator at 200 mbar. The outgoing melt was reheated to 189° C. in a falling-film evaporator likewise at 200 mbar and collected in a vessel. After a residence time of 20 minutes, the melt was pumped into the following three stages of similar structure. The conditions in the second / third / fourth stages were 100 / 74 / 40 mbar, 218 / 251 / 276°C a...

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Abstract

The invention relates to a method for preparing diaryl carbonates and polycarbonates, especially to a method for continuously preparing diaryl carbonates by using phosgene and at least one hydroxy compound (monohydric phenol) with the presence of a catalyst, and the usage thereof for preparing polycarbonates. Hydrogen chloride generated through a reaction is converted into chlorine through electrochemical oxidation, and the chlorine is then recirculated for preparation of phosgene. Especially, the method comprises a method (DPC method) of preparing diphenyl carbonate with generated hydrogen chloride.

Description

technical field [0001] The present invention relates to a process for the preparation of diaryl carbonates and polycarbonates. Background technique [0002] The field of the invention relates to a process for the continuous preparation of diaryl carbonates from phosgene and at least one monohydroxy compound (monohydric phenol) in the presence of a catalyst and its use for the preparation of polycarbonates. The hydrogen chloride formed in this reaction is converted by electrochemical oxidation into chlorine gas which is recycled for the production of phosgene. In particular, the method includes a method using the generated hydrogen chloride for the production of diphenyl carbonate (DPC method). [0003] It is known that diaryl carbonates, especially diphenyl carbonate, can be prepared by phase boundary phosgenation of monohydric phenols in the presence of bases and catalysts (Schotten-Baumann reaction) in inert solvents. Here, the use of solvents and sodium hydroxide is dis...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C69/96C07C68/02C08G64/30
CPCC07C68/02C08G64/307C25B1/26Y02P20/10C07C69/96C07C68/08C08G64/04
Inventor P.乌姆斯A.布兰
Owner COVESTRO DEUTSCHLAND AG
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