Process for the preparation of high-purity bisphenol A

• US 20070004941A1
• Filed: 06/05/2006
• Published: 01/04/2007
• Est. Priority Date: 06/04/2005
• Status: Abandoned Application

• Current Assignee: Covestro Deutschland AG
• Original Assignee: Covestro Deutschland AG
• Inventors: Zank, Jesko, Blaschke, Ulrich, Audenaert, Raymond, Braun, Arne, Westernacher, Stefan
• Application Number:
  US11/446,368
• Publication Number:
  US 20070004941A1
• Time in Patent Office: Days
• US Class Current: 568/728
• CPC Class Codes: C07C 37/20 using aldehydes or ketones
• CPC Class Codes: C07C 37/84 by crystallisation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes

Abstract

A process for the preparation of high purity bisphenol A is disclosed. The multi-step process entails a process whereby bisphenol A of a purity of preferably at least 99.8% can be obtained.

Claims

1. A process for the preparation of bisphenol A comprising:

a) reacting phenol with acetone in the presence of an acidic ion exchanger and a sulfur-containing co-catalyst to produce a product mixture comprising bisphenol A, phenol, BPA isomers, un-reacted acetone, and water;

b) continuously obtaining from the product mixture crystals of bisphenol A-phenol adduct by suspension crystallization in at least one crystallizer provided with at least one heat exchanger, said product mixture containing 0.1 to 6% by weight of water,

c) separating the adduct obtained in (b) by a first solid-liquid separation to obtain a first solid phase and a first liquid phase,

d) washing the first solid phase with a solution comprising phenol to obtain a washed solid phase and a second liquid phase,

e) distilling the first liquid phase and said second liquid phase to obtain a dewatered solution comprising 5 to 15 wt.-% p,p-BPA, 3 to 12 wt.-% isomers of BPA and less than 0.3 wt.-% water, the percentages based on the weight of the dewatered solution,

f) optionally introducing at least 90 wt.-% by weight of the dewatered solution into (a),

g) adding phenol to the washed solid phase obtained in (d) to obtain a homogeneous material system comprising 15 to 35 wt.-% p,p′

-BPA, 0.05 to 2 wt.-% isomers of BPA and 0.1 to 10 wt.-% water,

h) continuously obtaining from the homogeneous material system crystals of bisphenol A-phenol adduct by suspension crystallization in at least one crystallizer provided with at least one heat exchanger,

i) separating the crystals obtained in (h) by a second solid-liquid separation to obtain a second solid phase,

j) washing the second solid phase with a solution comprising phenol to obtain a washed adduct, and

k) optionally heating the washed adduct to at least 120°

C. to at least potentially remove phenol.

2. A process according to claim 1, wherein 50 to 90 wt.-%, of a liquid phase obtained in (i) and (j) is used in (g).

3. A process according to claim 1, wherein 10 to 50 wt.-%, of a liquid phase obtained in (i) and (j) is recycled into (d) for washing.

4. A process according to claim 1, wherein the solution comprising phenol in (j) comprises not more than 1.0% by weight of isopropenylphenol BPA and isomers thereof, and any secondary components.

5. A process according to claim 1, wherein the washed solid phase obtained in (d) is first melted before phenol is added in (g).

6. A process according to claim 1, wherein at least one of said first and/or second solid-liquid separation is carried out in a vacuum rotary filter.

7. A process according to claim 1, wherein the solution comprising phenol of (d) comprises 84 to 99.45 wt.-% phenol, 0.5 to 15 wt.-% BPA and 0.05 to 1.0 wt.-% BPA isomers, the percentages based on the weight of all components of the solution except water.

8. A process according to claim 1, wherein the solution comprising phenol of (d) comprises 0.05 to 12 wt.-% water, the percentage based on the total weight of said solution.

9. A process according to claim 1, wherein 5 to 100 wt.-% of the solution comprising phenol of (d) originates from (i) and (j).

10. A process according to claim 1, wherein the crystallization of (b), is carried out in two steps in series at temperatures that differ one from the other, and wherein the crystallization of (h) is carried out in one step in at least two crystallizers operating in parallel.

11. A process according to claim 1, wherein the material system of (g) comprises at most 5 wt.-% acetone, the percentage based on the weight of the system.

12. A process according to claim 1, wherein at least part of a liquid phase from the solid-liquid separation of (i) and at least part of a liquid phase from washing in (j) are collected separately, at least part of the liquid phase from the solid-liquid separation of (i) is recycled into (d) and/or at least part of the liquid phase from the washing is recycled into (g).

13. A process according to claim 1, wherein 0 to 35 wt.-%, of liquid phases obtained in (i) and/or (O) is evaporated, such that a top product is passed to (d) and/or (f) and a bottom product is recycled upstream of (b).

14. A bisphenol-A product produced in a single production facility having a purity of at least 99.8% p,p′

bisphenol A, a color index at most 20 Hazen units and a temperature stability of not more than 40 Hazen units;

said percentage based on the weight of the product except phenol.

15. A bisphenol-A product of claim 14, that has been produced by at least two crystallization steps.

16. A process for producing BPA with two categories of purity, said process comprising conducting a one stage and a two stage crystallization and a product work-up to produce BPA having a purity of 99.5-99.75%, and conducting a one stage and a two stage crystallization and a product work-up to produce BPA with a purity of at least 99.8%.

17. A process of claim 16 wherein said crystallizations are all conducted in the same production facility.

18. A process for the preparation of bisphenol A comprising:

a) reacting phenol with acetone in the presence of an acidic ion exchanger and a sulfur-containing co-catalyst to produce a product mixture comprising bisphenol A, phenol, BPA isomers, un-reacted acetone, and water;

b) continuously obtaining from the product mixture crystals of bisphenol A-phenol adduct by suspension crystallization in at least one crystallizer provided with at least one heat exchanger, said product mixture containing 0.1 to 6% by weight of water,

c) separating the adduct obtained in (b) by a first solid-liquid separation to obtain a first solid phase and a first liquid phase,

d) washing the first solid phase with a solution comprising phenol to obtain a washed solid phase and a second liquid phase,

e) distilling the first liquid phase and said second liquid phase to obtain a dewatered solution comprising less than 0.3 wt.-% water, the percentages based on the weight of the dewatered solution,

f) optionally introducing at least a portion of the dewatered solution into (a),

g) adding phenol to the washed solid phase obtained in (d) to obtain a homogeneous material system comprising 15 to 35 wt.-% p,p′

-BPA, 0.05 to 2 wt.-% isomers of BPA and 0.1 to 10 wt.-% water,

h) continuously obtaining from the homogeneous material system crystals of bisphenol A-phenol adduct by suspension crystallization in at least one crystallizer provided with at least one heat exchanger,

i) separating the crystals obtained in (h) by a second solid-liquid separation to obtain a second solid phase,

j) washing the second solid phase with a solution comprising phenol to obtain a washed adduct, and

k) optionally heating the washed adduct to at least 120°

C. to at least partially remove phenol.