Extraction process for removal of impurities from an oxidizer purge stream in the synthesis of carboxylic acid
View Patent ↗Disclosed is a process that relates to the recovery of a metal catalyst from an oxidizer purge stream produced in the synthesis of carboxylic acid, typically terephthalic acid. The process involves the addition of a wash solution to a high temperature molten dispersion to recover the metal catalyst and then subjecting an aqueous mixture or purified aqueous mixture so formed to a single stage extraction to remove organic impurities to produce an extract stream and a raffinate stream comprising the metal catalyst.
1. A process to produce a high boiling point organic impurities stream from an aqueous mixture said process comprising:
(a) adding an extraction solvent to said aqueous mixture in an extraction zone to form an extract stream and a raffinate stream; wherein said extraction zone comprises at least one extractor; and
(b) separating said extract stream and a solvent-rich stream in a separation zone to form said high boiling point organic impurities stream; wherein said solvent rich stream is produced by evaporating a mother liquor; wherein said mother liquor is withdrawn from a carboxylic acid synthesis process and wherein said mother liquor comprises a carboxylic acid, water, a solvent, and a metal catalyst; and wherein said carboxylic acid comprises at least one compound selected from the group consisting of terephthalic acid, benzoic acid, p-toulic acid, isophthalic acid, trimellitic acid, naphthalene dicarboxylic acid, and 2,5-diphenyl-terephthalic acid.
2. The process according to claim 1 wherein said extractor is a single stage extractor.
3. A process according to claim 1 wherein said solvent rich stream comprises acetic acid.
4. The process according to claim 1 wherein said extractor is operated at a temperature of about 40° C. to about 60° C.
5. The process according to claim 2 wherein said extractor is operated at a temperature of about 40° C. to about 60° C.
6. The process according to claim 3 wherein said extractor is a single stage extractor.
7. The process according to claim 1 wherein said extractor is a counter current extractor.
8. A process to produce a high boiling point organic impurities stream from a purified aqueous mixture said process comprising:
(a) adding an extraction solvent to said purified aqueous mixture in an extraction zone to form an extract stream and a raffinate stream; wherein said extraction zone comprises at least one extractor; and
(b) separating said extract stream and a solvent-rich stream in a separation zone to form said high boiling point organic impurities stream; wherein said solvent rich stream is produced by evaporating a mother liquor: wherein said mother liquor is withdrawn from a carboxylic acid synthesis process and wherein said mother liquor comprises a carboxylic acid, water, a solvent, and a metal catalyst and wherein said carboxylic acid comprises at least one compound selected from the group consisting of terephthalic acid and isophthalic acid.
9. The process according to claim 8 wherein said extractor is a single stage extractor.
10. A process according to claim 8 wherein said solvent rich stream comprises acetic acid.
11. The process according to claim 8 wherein said extractor is operated at a temperature of about 40° C. to about 60° C.
12. The process according to claim 9 wherein said extractor is operated at a temperature of about 40° C. to about 60° C.
13. The process according to claim 10 wherein said extractor is a single stage extractor.
14. The process according to claim 8 wherein said extractor is a counter current extractor.