PROCESS FOR THE PREPARATION OF DIALKYL TEREPHTHALATES FROM RECYCLE FEEDSTOCKS

• US 20190308925A1
• Filed: 06/23/2017
• Published: 10/10/2019
• Est. Priority Date: 06/27/2016
• Status: Abandoned Application

• Current Assignee: SABIC Global Technologies BV (Government of Saudi Arabia)
• Original Assignee: SABIC Global Technologies BV (Government of Saudi Arabia)
• Inventors: Patil, Prashant, Ganapathy Bhotla, Venkata Ramanarayanan, Nandy, Ritesh
• Application Number:
  US16/308,954
• Publication Number:
  US 20190308925A1
• Time in Patent Office: Days
• CPC Class Codes: C07C 67/03 by reacting an ester group with a hydroxy group
• CPC Class Codes: C07C 67/56 by solid-liquid treatment; by chemisorption
• CPC Class Codes: C07C 67/58 by liquid-liquid treatment
• CPC Class Codes: C07C 69/82 Terephthalic acid esters
• CPC Class Codes: C08K 5/12 of cyclic polycarboxylic acids
• CPC Class Codes: Y02P 20/582 Recycling of unreacted starting or intermediate materials

Abstract

A process for the preparation of a di(C_6-21 alkyl) phthalate combining a recycle poly((C_1-4 alkyl) terephthalate), a molar excess of a C_6-21 alcohol relative to the poly(C_1-4 alkyl) terephthalate), and a catalyst comprising sulfuric acid, a C_1-30 sulfonic acid, a tetra(C_1-6 alkyl) titanate, or a combination comprising at least one of the foregoing, to provide a reaction mixture; and heating the reaction mixture at a temperature greater than 130° C., under conditions effective to provide a product mixture comprising the di(C_7-13 alkyl) terephthalate.

Claims

1. A process for the preparation of a di(C_6-21alkyl) terephthalate, comprising:

combining a recycle poly((C_1-4 alkyl) terephthalate), a molar excess of a C_6-21 alcohol relative to the poly((C_1-4 alkyl) terephthalate), and a catalyst comprising sulfuric acid, a C_1-30 sulfonic acid, a tetra(C_1-6 alkyl) titanate, or a combination comprising at least one of the foregoing, to provide a reaction mixture; and

heating the reaction mixture at a temperature greater than 130°

C., under conditions effective to provide a product mixture comprising the di(C_7-13alkyl) terephthalate.

2. The process of claim 1, wherein

the poly((C_1-4alkyl) terephthalate) is a poly(ethylene terephthalate), a poly(butylene terephthalate, or a combination comprising at least one of the foregoing;

the C_6-21 alcohol is a C_6-13 alcohol; and

the acid catalyst is sulfuric acid, methanesulfonic acid, or tetra(isopropyl) titanate.

3. The process claim 1, wherein

a ratio of moles of terephthalate units in the recycle poly((C_1-4 alkyl) terephthalate) to moles of the C_6-21 alcohol is 1:

2.2 to 1;

10; and

the acid catalyst is present in an amount of 0.1 to 0.5 mole percent, based on the poly((C_1-4 alkyl) terephthalate).

4. The process claim 1, wherein heating the reaction mixture is at a temperature of 160 to 260°

C., at a pressure of 0.2 to 10 bar, and for 1 to 8 hours.

5. The process of claim 1, wherein the product mixture further comprises residual C_6-21 alcohol, water, a C_1-4 alkanol, a C_2-8 glycol, a C_2-8 dialkylene glycol, or a combination comprising at least one of the foregoing.

6. The process of claim 1, further comprising at least one of:

distilling the product mixture to remove at least a portion of the residual C_6-21 alcohol, the C_1-4 alkanol, the C_2-8 glycol, or a combination comprising at least one of the foregoing from the product mixture;

neutralizing the catalyst in the product mixture;

removing any solids from the product mixture;

or

treating the product mixture with a decolorizing agent.

7. The process of claim 6, wherein the distilled C_6-21 alcohol has a purity of greater than 98%, or greater than 99%, as determined by gas chromatography.

8. The process of claim 6, wherein neutralizing the catalyst comprises cooling the product mixture to a temperature of less than 100°

C., then adding an aqueous alkaline solution.

9. The process of claim 6, wherein

removing any solids comprises filtering the product mixture to provide a filtrate comprising the di(C_6-21alkyl) terephthalate.

10. The process of claim 6, wherein

treating the product mixture with activated charcoal comprises treating the distilled and neutralized the product mixture.

11. The process of claim 1, wherein the di(C_6-21 alkyl) terephthalate comprises less than 5 wt % of the isophthalate diester, based on the weight of the di(C_6-21 alkyl) terephthalate.

12. The process of claim 1, wherein the yield of the di(C_6-21alkyl) terephthalate is greater than 85% based on the moles of terephthalate units in the poly((C_1-4 alkyl) terephthalate).

13. The process of claim 1, wherein the di(C_6-21 alkyl) terephthalate has a color of less than 35, determined according to ASTM D1209.

14. The process of claim 1, wherein

the recycle poly(C_1-4 alkyl terephthalate) is poly(ethylene terephthalate), poly(butylene terephthalate, or a combination comprising at least one of the foregoing;

the C_1-4 alcohol is 2-ethyl hexanol; and

the di(C_6-21alkyl) terephthalate is di(2-ethylhexyl) terephthalate.

15. A di(C_6-21alkyl) terephthalate made by the process of claim 1.

16. The process of claim 2, wherein

the C_6-21 alcohol is a C_6-13 alcohol,

a ratio of moles of terephthalate units in the recycle poly((C_1-4 alkyl) terephthalate) to moles of the C_6-13 alcohol is 1:

3 to 1;

6;

the acid catalyst is present in an amount of 0.1 to 0.5 mole percent, based on the poly((C_1-4 alkyl) terephthalate);

heating the reaction mixture is at a temperature of 160 to 260°

C., at a pressure of 0.2 to 10 bar, for 1 to 8 hours; and

the product mixture further comprises residual C_6-13 alcohol, water, a C_1-4 alkanol, a C_2-8 glycol, a C_2-8 dialkylene glycol, or a combination comprising at least one of the foregoing.

17. The process of claim 16, wherein

the recycle poly(C_1-4 alkyl terephthalate) is poly(ethylene terephthalate), poly(butylene terephthalate, or a combination comprising at least one of the foregoing;

the C_1-4 alcohol is 2-ethyl hexanol; and

the di(C_6-21alkyl) terephthalate is di(2-ethylhexyl) terephthalate.

18. The process of claim 16, further comprising at least one of:

distilling the product mixture to remove at least a portion of the residual C_6-13 alcohol, the C_1-4 alkanol, the C_2-8 glycol, or a combination comprising at least one of the foregoing from the product mixture;

neutralizing the catalyst in the product mixture;

removing any solids from the product mixture;

or

treating the product mixture with a decolorizing agent, preferably an activated charcoal.

19. The process of claim 17, wherein

the distilled C_6-13 alcohol has a purity of greater than 99%, as determined by gas chromatography;

neutralizing the catalyst comprises cooling the product mixture to a temperature of less than 100°

C., then adding an aqueous alkaline solution;

removing any solids comprises filtering the product mixture to provide a filtrate comprising the di(C_6-21 alkyl) terephthalate;

treating the product mixture with activated charcoal comprises treating the distilled and neutralized the product mixture;

the yield of the di(C_6-21 alkyl) terephthalate is greater than 85%;

the di(C_6-21 alkyl) terephthalate comprises less than 5 wt %, based on the weight of the di(C_6-21 alkyl) terephthalate; and

the di(C_6-21 alkyl) terephthalate has a color of less than 35, determined according to ASTM D1209.