Process for the oxidative purification of terephthalic acid
First Claim
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1. A process to produce a purified carboxylic acid slurry composition said process comprising:
- (a) removing impurities from a crude carboxylic acid slurry composition in a solid liquid displacement zone to form a slurry composition;
(b) oxidizing said slurry composition at a temperature of about 190°
C. to about 280°
C. in a staged oxidation zone to form a staged oxidation composition;
(c) crystallizing said staged oxidation composition in a crystallization zone to form a crystallized composition; and
(d) removing in a subsequent solid liquid displacement zone impurities from said crystallized composition to from said purified carboxylic acid slurry composition;
wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone; and
wherein said subsequent solid liquid displacement zone comprises at least one solid liquid separator that is operated at a temperature between 110°
C. to 200°
C.
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Abstract
Disclosed is a process to produce a purified carboxylic acid slurry. The process comprises removing impurities from a crystallized product in a solid liquid displacement zone to form the purified carboxylic acid slurry. The process produces purified carboxylic acid slurry having good color and low impurity levels without the use of purification steps like hydrogenation or an impurity removal process.
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Citations
20 Claims
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1. A process to produce a purified carboxylic acid slurry composition said process comprising:
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(a) removing impurities from a crude carboxylic acid slurry composition in a solid liquid displacement zone to form a slurry composition;
(b) oxidizing said slurry composition at a temperature of about 190°
C. to about 280°
C. in a staged oxidation zone to form a staged oxidation composition;
(c) crystallizing said staged oxidation composition in a crystallization zone to form a crystallized composition; and
(d) removing in a subsequent solid liquid displacement zone impurities from said crystallized composition to from said purified carboxylic acid slurry composition;
wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone; and
wherein said subsequent solid liquid displacement zone comprises at least one solid liquid separator that is operated at a temperature between 110°
C. to 200°
C. - View Dependent Claims (3, 4, 5, 6, 7, 10, 11, 20)
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2. A process to produce a purified carboxylic acid slurry composition said process comprising:
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(a) removing impurities from a crude carboxylic acid slurry composition in a solid liquid displacement zone to form a slurry composition;
(b) oxidizing said slurry composition at a temperature of about 190°
C. to about 280°
C. in a staged oxidation zone to form a staged oxidation composition;
(c) removing in a subsequent solid displacement zone impurities from said staged oxidation composition to form a purified staged oxidation composition;
wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone; and
wherein said subsequent solid liquid displacement zone comprises at least one solid liquid separator that is operated at a temperature between 110°
C. to 200°
C.; and
(d) crystallizing in a crystallization zone said purified staged oxidation composition to form said purified carboxylic slurry composition.
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8. A process to produce a purified carboxylic acid slurry composition comprising:
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(a) removing in a solid liquid displacement zone impurities from a crude carboxylic acid slurry composition to form a slurry composition;
wherein said crude carboxylic acid slurry composition comprises terephthalic acid, catalyst, acetic acid, and impurities that is withdrawn at a temperature between about 140°
C. and about 170°
C. from the oxidation of paraxylene in a primary oxidation zone;
wherein said catalyst comprises cobalt, manganese or bromine compounds;
(b) 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.; and
wherein said oxidizing is at a higher temperature in said staged oxidation zone than in said primary oxidation zone;
(c) crystallizing said staged oxidation composition in a crystallization zone to form a crystallized composition; and
(d) removing in a subsequent solid liquid displacement zone impurities from said crystallized composition to form said purified carboxylic acid slurry composition;
wherein said subsequent solid liquid displacement zone comprises at least one solid liquid separator that is operated at a temperature between 110°
C. to 200°
C.; and
wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone. - View Dependent Claims (9, 12)
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13. A process to produce a purified carboxylic acid slurry composition said process comprising:
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(a) oxidizing an aromatic feedstock at a temperature of about 110°
C. to about 200°
C. in a primary oxidation zone to form a crude carboxylic acid slurry composition;
(b) removing impurities from said crude carboxylic acid slurry composition in a solid liquid displacement zone to form a slurry composition;
(c) oxidizing said slurry composition in a staged oxidation zone to form a staged oxidation composition;
(d) removing in a subsequent solid liquid displacement zone impurities from said staged oxidation composition to form a purified staged oxidation composition;
wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone; and
wherein said subsequent solid liquid displacement zone comprises at least one solid liquid separator that is operated at a temperature between 110°
C. to 200°
C.; and
(e) crystallizing in a crystallization zone said purified staged oxidation composition to form said purified carboxylic acid slurry composition. - View Dependent Claims (15, 16, 17, 18, 19)
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14. A process to produce a purified carboxylic acid slurry composition said process comprising:
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(a) oxidizing an aromatic feedstock at a temperature of about 110°
C. to about 200°
C. in a primary oxidation zone to form a crude carboxylic acid slurry composition;
(b) removing impurities from said crude carboxylic acid slurry composition in a solid liquid displacement zone to form a slurry composition;
(c) oxidizing said slurry composition in a staged oxidation zone to form a staged oxidation composition;
(d) crystallizing said staged oxidation composition in a crystallization zone to form a crystallized composition; and
(e) removing in a subsequent solid liquid displacement zone impurities from said crystallized composition to form said purified carboxylic acid slurry composition;
wherein said impurities comprise 4-carboxybenzaldehyde, trimellitic acid, or 2,6-dicarboxyfluorenone; and
wherein said subsequent solid liquid displacement zone comprises at least one solid liquid separator that is operated at a temperature between 110°
C. to 200°
C.
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Specification