Process for the purification of a crude carboxylic acid slurry
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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Abstract
Disclosed is a process to produce a purified carboxylic acid product. The process comprises removing impurities from a crude carboxylic acid slurry in a solid-liquid displacement zone to form a slurry product. The slurry product if further treated in a staged oxidation zone and a crystallization zone to from a crystallized product. The crystallized product is further cooled in a cooling zone and subsequently filtered and dried in a filtration and drying zone. The process produces purified carboxylic acid product having good color and low impurity levels without the use of purification steps like hydrogenation.
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Citations
14 Claims
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1. A process to produce a purified carboxylic acid composition comprising:
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(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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A process to produce a purified carboxylic acid composition comprising:
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(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 said oxidizing is conducted at a temperature between about 120°
C. to about 200°
C.; and
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 said impurities 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 a 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 acid slurry in a filtration and drying zone to produce said purified carboxylic acid composition. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification