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Process for producing polycarbonate

  • US 8,106,144 B2
  • Filed: 05/21/2010
  • Issued: 01/31/2012
  • Est. Priority Date: 06/04/2009
  • Status: Active Grant
First Claim
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1. A process for producing polycarbonate comprising:

  • a) producing phosgene by reacting chlorine with carbon monoxide;

    b) reacting the phosgene formed in step a) with at least one bisphenol in the presence of an aqueous alkali metal containing base to form a polycarbonate and an alkali metal chloride-containing reaction waste water solution;

    c) separating off and working up the polycarbonate formed in step b) from the alkali metal chloride-containing reaction waste water solution;

    e) distilling at least a portion of the alkali metal chloride-containing reaction waste water solution remaining after step c) via osmotic membrane distillation to obtain an enriched alkali metal chloride-containing solution;

    f) electrochemically oxidating of at least a portion of the alkali metal chloride-containing solution from e) to obtain chlorine, an alkali metal hydroxide solution and, optionally, hydrogen.

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