Economical purification of bisphenol a

• US 20040044254A1
• Filed: 09/29/2003
• Published: 03/04/2004
• Est. Priority Date: 11/16/2000
• Status: Active Grant

• Current Assignee: Badger Licensing LLC (TechnipFMC, plc)
• Original Assignee: Dave P. Palmer, Steven D. Evitt
• Inventors: Palmer, DAve P., Evitt, Steven D.
• Granted Patent: US 6,806,394 B2
• Time in Patent Office: Days
• US Class Current: 568/724
• CPC Class Codes: C07C 37/685 Processes comprising at least two steps in series
• CPC Class Codes: C07C 37/84 by crystallisation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes

Abstract

Process and related apparatus are disclosed for economically producing a very high quality bisphenol A product by a multistage crystallization process utilizing a new cross-flow wash design whereby a high purity wash phenol stream is fed to every washing stage, optionally also in combination with a modified stream flow/recycle design which avoids increased by product production and yield losses otherwise expected from processing increased volumes of wash phenol.

Claims

1. In a process for the purification of bisphenol A via crystallization of phenol adduct from a phenol solution in a multistage process, the improvements comprising the steps of

a. producing phenol adduct crystals in each of a plurality of purification stages;

and,

b. washing the phenol adduct crystals produced in each of said purification stages with a high purity wash phenol stream that is substantially free of bisphenol isomers and impurities.

2. A process according to claim 1 further comprising the step of dewatering the phenol adduct crystals from each stage before washing them with said high purity phenol stream.

3. A process according to claim 1 further wherein the liquid feed stream to the first upstream purification stage comprises about 30-60% by weight of p,p′

-BPA.

4. A process according to claim 1 further wherein the liquid feed stream to the first upstream purification stage comprises about 30-55% by weight of p,p′

-BPA.

5. A process according to claim 1 further comprising the step of recycling at least a first portion of spent wash or separated mother liquor from one or more of said purification stages for use as a dilution solvent to reduce the concentration of p,p′

-BPA in the mixed crystalliation feed to the first upstream purification stage to below 40% by weight.

6. A process according to claim 1 further comprising the step of recycling at least a first portion of spent wash or separated mother liquor from one or more of said purification stages for use as a dilution solvent to reduce the concentration of p,p′

-BPA in the mixed crystallization feed to the first upstream purification stage to about 25-40% by weight.

7. A process according to claim 5 further comprising the step of recycling at least a second portion of said spent wash or separated mother liquor to the crystallizers in the first purification stage.

8. A process according to claim 7 further comprising the step of recycling remaining spent wash and separated mother liquor to a reaction system for production of p,p′

-BPA.

9. A process according to claim 8 wherein said p,p′

-BPA is produced by condensation of acetone with phenol or from the reaction of heavy byproducts.

10. A process according to claim 1 wherein said high purity wash phenol stream includes fresh makeup phenol to the process.

11. A process according to claim 1 wherein said high purity wash phenol stream includes phenol produced in a downstream step of devolatilizing BPA-phenol adduct recovered from the final solid/liquid separation step to produce phenol and a molten BPA product stream.

12. A process according to claim 1 wherein said high purity wash phenol stream is produced by volatilization of phenol from the BPA process.

13. A process according to claim 12 further wherein said phenol-containing process stream originates from a condensation reactor.

14. A process according to claim 7 wherein a predominant proportion of said spent wash is preferentially recycled to the first crystallization stage.

15. A process according to claim 1 wherein spent wash from downstream crystallization stages is recycled to the first crystallization stage.

16. In a process for the purification of bisphenol A via crystallization of phenol adduct from a phenol solution in a multistage process, the improvements comprising the steps of:

a producing phenol adduct crystals in each of a plurality of purification stages; and

,

b. washing the phenol adduct crystals produced in each of said purification stages with a high purity wash phenol stream that is substantially free of bisphenol isomers and impurities, wherein phenol adduct crystals produced in at least the final downstream purification stage, and, optionally, in one or more other downstream purification stages are washed with fresh makeup phenol fed to the process, or with phenol produced from a finishing step for obtaining a final BPA adduct product, or a mixture thereof, and further wherein phenol adduct crystals produced in the first upstream purification stage, and, optionally, in one or more other upstream purification stages are washed with phenol produced from phenol-containing effluents produced in the BPA process.

17. A process according to claim 16 further comprising the step of dewatering the phenol adduct crystals from each stage before washing them with said high purity phenol stream.

18. A process according to claim 16 further wherein at least a portion of separated mother liquor or spent wash produced from the multistage crystallization is recycled immediately upstream of or to the first stage adduct crystallization stage.

19. A process according to claim 18 further wherein remaining separated mother liquor and spent wash are recycled to a reaction system for the production of p,p′

-BPA either from the condensation of acetone with phenol or from the reaction of heavy byproducts.

20. A process according to claim 16 further wherein mother liquor and spent wash produced from the downstream crystallization stages are preferentially recycled to the first crystallization stage.

21. A process according to claim 20 further wherein spent wash is recycled preferentially to the mother liquor.

22. A process for the purification of bisphenol A via adduct crystallization of phenol adduct from a phenol solution in a multistage process wherein the adduct crystals are separated from the mother liquor, dewatered, and washed with a phenol stream substantially free of bisphenol isomers and impurities.

23. A process according to claim 22 wherein the phenol stream for washing includes makeup phenol to the process.

24. A process according to claim 22 wherein the phenol stream for washing includes phenol produced from the finishing of BPA-phenol adduct to produce BPA.

25. A process according to claim 22 wherein the phenol stream for washing includes phenol produced from phenol-containing process streams within the BPA process.

26. A process for the purification a bisphenol A via crystallization of phenol adduct from a phenol solution in an multistage process wherein the adduct crystals of each purification stage are separated from the mother liquor, dewatered, and washed with a phenol stream substantially free of bisphenol isomers and impurities, the downstream stages being preferentially washed with makeup phenol to the process or phenol produced from the finishing of phenol-BPA adduct, and the upstream stages being washed with a slightly less pure phenol produced from phenol-containing process streams within the BPA process.