Extraction process for removal of impurities from mother liquor in the synthesis of carboxylic acid
View Patent ↗A method for removing impurities from a mother liquor comprising a carboxylic acid, a metal catalyst, impurities by (a) evaporating the mother liquor comprising a carboxylic acid, a metal catalyst, impurities and a solvent in a first evaporator zone to produce a vapor stream and a concentrated mother liquor stream; (b) evaporating the concentrated mother liquor stream in a second evaporator zone to form a solvent rich stream and a super concentrated mother liquor stream; (c) mixing in a mixing zone a water-solvent solution and optionally an extraction solvent with the super concentrated mother liquor stream to form an aqueous mixture; (d) optionally separating organic impurities from the aqueous mixture in a solid-liquid separation zone to form a purified aqueous mixture; and (e) extracting the aqueous mixture or purified aqueous mixture with an extraction solvent in an extraction zone to form an extract stream and the raffinate stream.
1. A process comprising:
(a) evaporating a mother liquor comprising a carboxylic acid, a metal catalyst, impurities, water and a solvent in a first evaporator zone to produce a vapor stream and a concentrated mother liquor stream;
(b) evaporating said concentrated mother liquor stream in a second evaporator zone to form a solvent rich stream and a super concentrated mother liquor stream; wherein said super concentrated mother liquor stream is a high temperature molten dispersion; wherein said evaporating in said second evaporator zone is conducted at a temperature from about 150° C. to about 220° C.;
(c) mixing in a mixing zone a water-solvent solution and optionally an extraction solvent with said super concentrated mother liquor stream to form an aqueous mixture;
(d) adding an extraction solvent to said aqueous mixture in an extraction zone to form an extract stream and a raffinate stream; and
(e) separating said extract stream and said solvent rich stream in a separation zone to form a high boiling point organic impurities stream and a recovered extraction solvent stream.
2. The process according to claim 1 wherein about 50 wt % to about 80 wt % of said solvent is removed from said mother liquor in step (a).
3. The process according to claim 1 wherein about 95 wt % to about 99 wt % of said solvent and water is removed from said mother liquor in step (a) and step (b) combined.
4. The process according to claim 1 wherein said extraction solvent is optionally added in step (c) in an amount of about 1 to about 10 percent by weight.
5. The process according to claim 1 wherein said water-solvent solution is added to quench said aqueous mixture to a temperature range of about 60° C. to about 95° C.
6. A process according to claim 1 wherein said extraction zone comprises a counter current extractor.
7. A process according to claim 1 wherein said extraction zone comprises a single stage extractor.
8. A process according to claim 1 wherein said solvent rich stream comprises a solvent selected from the group consisting of n-propyl acetate, isopropyl acetate, isobutyl acetate, sec-butyl acetate, ethyl acetate and n-butyl acetate.
9. A process according to claim 1 wherein said second evaporator zone comprises an evaporator operated at a temperature of about 150° C. to about 200° C.
10. A process according to claim 1 where said first evaporator zone is operated at a pressure of greater that 14.6 psia.
11. A process comprising:
(a) evaporating a mother liquor comprising a carboxylic acid, a metal catalyst, impurities, water and a solvent in a first evaporator zone to produce a vapor stream and a concentrated mother liquor stream;
(b) evaporating said concentrated mother liquor stream in a second evaporator zone to form a solvent rich stream and a super concentrated mother liquor stream; wherein said super concentrated mother liquor stream is a high temperature molten dispersion; wherein said evaporating in said second evaporator zone is conducted at a temperature from about 150° C. to about 220° C.;
(c) mixing in a mixing zone a water-solvent solution with said super concentrated mother liquor stream to form an aqueous mixture;
(d) separating organic impurities from said aqueous mixture in a solid-liquid separation zone to form a purified aqueous mixture;
(e) adding an extraction solvent to said aqueous mixture or said purified aqueous mixture in an extraction zone to form an extract stream and a raffinate stream; and
(f) separating said extract stream and said solvent rich stream in a separation zone to form a high boiling point organic impurities stream and a recovered extraction solvent stream.
12. The process according to claim 11 wherein about 50 wt % to about 80 wt % of said solvent is removed from said mother liquor in step (a).
13. The process according to claim 11 wherein said water-solvent solution is added to quench said aqueous mixture to a temperature range of about 60° C. to about 95° C.
14. The process according to claim 11 wherein said water-solvent solution is added to quench said aqueous mixture to a temperature range of 80° C. to about 90° C.
15. The process according to claim 11 wherein said extraction zone comprises a counter current extractor.
16. The process according to claim 11 wherein said extraction zone comprises a single stage extractor.
17. The process according to claim 11 wherein said solvent rich stream comprises a solvent selected from the group consisting of n-propyl acetate, isopropyl acetate, isobutyl acetate, sec-butyl acetate, ethyl acetate and n-butyl acetate.