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Process for the purification of a crude carboxylic acid slurry

  • US 7,132,566 B2
  • Filed: 09/22/2003
  • Issued: 11/07/2006
  • Est. Priority Date: 09/22/2003
  • Status: Active Grant
First Claim
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1. A process to produce a purified carboxylic acid composition comprising:

  • (a) oxidizing an aromatic feed stock in a primary oxidation zone at an oxidizing temperature to form a crude carboxylic acid slurry composition;

    wherein said crude carboxylic acid slurry composition comprises at least one carboxylic acid;

    wherein there is less than 5% by weight terephthalic acid and isophthalic acid in said crude carboxylic acid slurry composition;

    (b) removing in a solid-liquid displacement zone impurities from said crude carboxylic acid slurry composition to form a slurry composition; and

    wherein saidimpurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone;

    (c) oxidizing said slurry composition in a staged oxidation zone to form a staged oxidation composition;

    wherein said oxidizing is conducted at an oxidizing temperature between about 190°

    C. to about 280°

    C.;

    wherein said oxidizing temperature in said staged oxidation zone is higher than the oxidizing temperature in said primary oxidation zone;

    (d) crystallizing said staged oxidation composition in a crystallization zone to form a crystallized composition;

    (e) cooling said crystallized composition in a cooling zone to form a cooled purified carboxylic acid slurry composition; and

    (f) filtering and optionally drying said cooled purified carboxylic slurry composition in a filtration and drying zone to produce said purified carboxylic acid composition.

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