Purification of bisphenol-A

• US 5,434,316 A
• Filed: 07/28/1994
• Issued: 07/18/1995
• Est. Priority Date: 07/28/1994
• Status: Expired due to Term

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Kissinger, Gaylord M.
• Primary Examiner(s): LONE, WERREN
• Application Number:
  US08/281,970
• Time in Patent Office: 355 Days
• Field of Search: 568/722, 568/724, 568/727, 568/728, 423/584
• US Class Current: 568/724
• CPC Class Codes: B01D 9/0013 by indirect heat exchange
• CPC Class Codes: B01D 9/0036 Crystallisation on to a bed of product crystals; Seeding
• CPC Class Codes: B01D 9/004 Fractional crystallisation; Fractionating or rectifying columns
• CPC Class Codes: C07C 37/84 by crystallisation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes

Abstract

Bisphenol-A produced by the condensation of acetone and phenol is freed of contaminant co-products by melting and crystallization in and from water. The final washing, in hot water, cleanses the crystal surfaces of remaining contaminants without the need for organic solvents.

Claims

1. A process for the purification of bisphenol-A by separating contaminants associated with the compound when prepared by the condensation of phenol with acetone in the presence of an acid catalyst, which comprises;

A. melting the contaminated bisphenol-A compound in an aqueous mixture;

B. crystallizing bisphenol-A from the aqueous mixture;

C. separating the crystals from the resulting aqueous mixture; and

D. washing the crystals with water at a temperature of from about 35°

C. to below the melting point of the crystals.

2. The process of claim 1 wherein the bisphenol-A is melted with water, the proportion of water comprising from 20 to 60 percent by weight of the aqueous mixture.

3. The process of claim 2 wherein the proportion of water comprises from 30 to 50 percent by weight of the aqueous mixture.

4. The process of claim 1 wherein the wash water is at a temperature of from about 90°

to about 155°

C.

5. The process of claim 4 wherein the wash water is at a temperature or about 95°

C.

6. The process of claim 1 carried out continuously.

7. The process of claim 1 which further comprises melting the washed crystals with water at a temperature above the melting point of the crystals.

8. The process of claim 7 wherein the water used to melt the washed crystals is the wash water used from washing said crystals.

9. The process of claim 8 carried out repetitively in a plurality of cycles of the steps B-D.

10. The process of claim 8 wherein the temperature of the wash water used to melt the crystals is at about 155°

C.

11. A process for the removal of contaminants associated with bisphenol-A prepared by the condensation of acetone with phenol in the presence of an acid catalyst, from the bisphenol-A, which comprises;

A. melting the bisphenol-A in an aqueous mixture, at a temperature within the range of from about 95°

to 100°

C. under atmospheric pressure;

B. crystallizing the bisphenol-A from the aqueous mixture, whereby a mother liquor remains, comprising water and organics;

separating the crystals from the mother liquor;

C. separating water from the mother liquor; and

D. washing the crystals with the water separated from the mother liquor, at a temperature above room temperature but below the melting point of the crystals.

12. The process of claim 11 wherein the bisphenol-A is melted with water, the proportion of water comprising from 20 to 60 percent by weight of the aqueous mixture.

13. The process of claim 12 wherein the steps A-D are carried out a plurality of times in sequence.

14. The process of claim 13 wherein the number of times is 2.

15. A process for removing the by-product contaminants of a procedure for the preparation of bisphenol-A by condensation of acetone with phenol, from the bisphenol product, which comprises;

A. melting the bisphenol-A product in an aqueous medium at a temperature of about 95°

to 100°

C. under atmospheric pressures;

B. crystallizing bisphenol-A from the aqueous medium, the residue medium containing organics and water;

C. separating the water from the residue medium;

D. melting the bisphenol-A crystals in water, whereby an aqueous mixture is formed;

E. crystallizing bisphenol-A from the aqueous mixture formed in step D; and

F. separating the bisphenol-A crystals from the aqueous mixture resulting in step E.

16. The process of claim 15 wherein the water in which the bisphenol-A crystals are melted in step (D) is fresh water.

17. The process of claim 15 wherein the water in which the bisphenol-A crystals are melted in step (D) is the water separated from the residue in step (C).

18. The process of claim 15 wherein the melting in step (C) is at a water temperature of about 155°

C. under atmospheric pressure.

19. The process of claim 15 carried out by repetition of steps A-F a plurality of times in sequence.

20. Apparatus for the removal of by-product contaminants from bisphenol-A prepared by condensation of acetone with phenol in the presence of an acid catalyst, which comprises;

a vertically disposed crystallizer column having an open top end and an open bottom end;

means on the exterior of the column for controlling temperature in the column;

a supply vessel mounted on the open top end of the column;

pump means connected by a conduit to the supply vessel;

a sump tank mounted on the open bottom end of the column;

a feed conduit for feeding the contaminated bisphenol-A to the sump tank; and

a conduit between the sump-tank and the pump means for circulating bisphenol-A from the sump tank.