Process for production of a dried carboxylic acid cake suitable for use in polyester production
View Patent ↗The present invention relates to a process by which a dried carboxylic acid cake is obtained from a slurry or cake carboxylic acid product through the use of at least one counter current wash. More specifically, the present invention relates to a process by which a dried terephthalic acid cake suitable as a starting material for polyester or co-polyester production is obtained from a slurry or cake terephthalic acid product through the use of at least one counter current wash.
1. A process for producing a dried carboxylic acid cake, said process comprising:
(a) oxidizing in an oxidation zone an aromatic feedstock to produce a carboxylic acid slurry;
(b) removing in a liquor exchange zone impurities from said carboxylic acid slurry to form a water-wet carboxylic acid cake, a mother liquor stream, a solvent mother liquor stream, and a solvent/water byproduct liquor stream; wherein at least one solvent is, added counter current to the flow of said carboxylic acid slurry; wherein said liquor exchange zone comprises one solid-liquid separation device capable of performing the removal of said impurities from said carboxylic acid slurry and producing said water-wet carboxylic acid cake from said carboxylic acid slurry; wherein said solvent comprises acetic acid, and
(c) drying said water-wet carboxylic acid cake in a drying zone to form said dried carboxylic acid cake; wherein said water-wet cake maintains the form of a cake between step (b) and (c).
2. The process according to claim 1 wherein said liquor exchange zone comprises from about 2 to about 4 stages of water or solvent counter current washes.
3. The process according to claim 1 wherein said solvent and said water is added counter current to the flow of said carboxylic acid slurry.
4. A process according to claim 1 wherein said carboxylic acid is selected from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid, and mixtures thereof.
5. A process according to claim 1 wherein said carboxylic acid is terephthalic acid.
6. A process according to claim 1 , 2 or 3 wherein said drying zone evaporates at least 10% of volatiles in said water-wet carboxylic acid cake.
7. A process according to claim 1 wherein said crude carboxylic acid slurry comprising terephthalic acid, catalyst, acetic acid, and impurities is withdrawn at a temperature between about 110° C. to about 200° C. from said oxidation zone; wherein said catalyst comprises cobalt, manganese and bromine compounds.
8. A process for producing a dried carboxylic acid cake, said process comprising:
(a) oxidizing in an oxidation zone an aromatic feedstock to produce a carboxylic acid slurry;
(b) removing in a solvent liquor exchange zone impurities from said carboxylic acid slurry to form a carboxylic acid cake with solvent, a mother liquor stream, and a solvent mother liquor stream; wherein said solvent comprises acetic acid;
(c) adding water in a counter current water wash zone to said carboxylic cake with solvent to produce a water-wet carboxylic acid cake and a solvent/water byproduct liquor stream; and
(d) drying said water-wet carboxylic acid cake in a drying zone to form said dried carboxylic acid cake wherein said water-wet cake maintains the form of a cake between step (c) and (d).
9. A process according to claim 8 wherein said carboxylic acid is selected from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid, and mixtures thereof.
10. A process according to claim 8 wherein said carboxylic acid is terephthalic acid.
11. A process according to claim 8 or 9 wherein said drying zone evaporates at least 10% of volatiles in said water-wet carboxylic acid cake.
12. A process according to claim 8 wherein said crude carboxylic acid slurry comprising terephthalic acid, catalyst, acetic acid, and impurities is withdrawn at a temperature between about 110° C. to about 200° C. from said oxidation zone; wherein said catalyst comprises cobalt, manganese and bromine compounds.
13. A process for producing a dried carboxylic acid cake, said process comprising the following steps in the order named:
(a) oxidizing in an oxidation zone an aromatic feedstock to produce a carboxylic acid slurry;
(b) removing in a solid-liquid separation zone impurities from said carboxylic acid slurry to form a slurry or cake product and a mother liquor stream;
(c) removing in a counter current solvent-water liquor exchange zone impurities from said slurry or cake product to form a water-wet carboxylic acid cake, a solvent mother liquor stream, and a solvent/water byproduct liquor stream; wherein said counter current solvent-water liquor exchange zone comprises one solid-liquid separation device; wherein said solvent comprises acetic acid; and
(d) drying said water-wet carboxylic acid cake in a drying zone to form said dried carboxylic acid cake wherein said water-wet cake maintains the form of a cake between step (c) and (d).
14. A process according to claim 13 wherein said carboxylic acid is selected from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic acid and mixtures thereof.
15. A process according to claim 13 wherein said carboxylic acid is terephthalic acid.
16. A process according to claim 13 wherein said crude carboxylic acid slurry comprising terephthalic acid, catalyst, acetic acid, and impurities is withdrawn at a temperature between about 110° C. to about 200° C. from said oxidation zone; and wherein said catalyst comprises cobalt, manganese and bromine compounds.
17. A process according to claim 13 or 14 wherein said drying zone evaporates at least 10% of volatiles in said water-wet carboxylic acid cake.
18. A process for producing a dried carboxylic acid cake, said process comprising the following steps in the order named:
(a) removing a solvent from a slurry or cake product in a counter current solvent-water liquor exchange zone; wherein a portion of the solvent in said slurry or cake product is replaced with water to form a water-wet carboxylic acid cake; wherein said counter current solvent-water liquor exchange zone comprises one solid-liquid separation device; wherein said solvent comprises acetic acid; and
(b) drying said water-wet carboxylic acid cake in a drying zone to form said dried carboxylic acid cake wherein said water-wet cake maintains the form of a cake between step (a) and (b).
19. A process according to claim 18 wherein said carboxylic acid is selected from a group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, trimellitic and mixtures thereof.
20. A process according to claim 18 wherein said carboxylic acid is terephthalic acid.
21. A process according to claim 19 wherein said crude carboxylic acid slurry comprising terephthalic acid, catalyst, acetic acid, and impurities is withdrawn at a temperature between about 110° C. to about 200° C. from said oxidation zone; and wherein said catalyst comprises cobalt, manganese and bromine compounds.
22. A process according to claim 18 or 19 wherein said drying zone evaporates at least 10% of volatiles in said water-wet carboxylic acid cake.