IP Library › Granted Patent US 12,410,296
Granted Patent B2
US 12,410,296 · App. 18/535,791 · Granted Sep 9, 2025

Use of multifunctional CO2 for depolymerization of polyethylene terephthalate

Inventors: Maohong Fan (Ames, IA); Wenyang Lu (Laramie, WY); Jinwen Zhang (Pullman, WA)
Assignees: UNIVERSITY OF WYOMING; WASHINGTON STATE UNIVERSITY
C08J11/14B01J3/008B01J3/02C08J2367/02
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Quick Facts
Patent No.
US 12,410,296
App. No.
18/535,791
Granted
Sep 9, 2025
Kind
B2
Abstract

A high-efficiency, low-energy consumption and environmental-friendly recycling technology for PETE plastic waste is disclosed. The degradation of PETE plastic waste includes a method for attacking the —O— ester linkage in the repeat unit of PETE plastic with water in saturated pressure and CO 2 in supercritical (Sc) conditions.

Claims (37)

1. A method for recycling polyethylene terephthalate (PETE), comprising:

pre-loading a reactor with a ratio of a polyethylene terephthalate and a deionized (DI) water;

injecting a CO2 into the reactor at an injection pressure;

heating the ratio of polyethylene terephthalate and a deionized water and CO2 within the reactor to a reaction temperature and for a reaction time;

reacting the polyethylene terephthalate with the deionized water and the CO2;

converting the polyethylene terephthalate to a liquid product and a solid product in the reactor, the converted polyethylene terephthalate is depolymerized; and

collecting the liquid product and the solid product from the reactor.

2. The method of claim 1 , wherein the solid product comprises terephthalic acid.

3. The method of claim 1 , wherein the reaction temperature comprises 160° C., 180° C., 200° C., 220° C., and 240° C.

4. The method of claim 1 , wherein the reaction time comprises 0.25 hrs, 0.5 hrs, 1 hr, 1.5 hrs, and 2.0 hrs.

5. The method of claim 1 , wherein the injection pressure comprises 700 psi.

6. The method of claim 1 , wherein the solid product reactant comprises polyenes and benzoic acid crystals.

7. The method of claim 1 , wherein the liquid product reactant comprises ethylene glycol.

8. The method of claim 1 , wherein the reactor comprises a supercritical high temperature reactor.

9. A method for recycling polyethylene terephthalate (PETE) by depolymerizing polyethylene terephthalate, the method comprising:

pre-loading a reactor with a weight ratio of a polyethylene terephthalate and a deionized (DI) water;

injecting CO2 into the reactor at an injection pressure;

sealing the weight ratio of the polyethylene terephthalate and the deionized water and the CO2 within the reactor;

heating the weight ratio of the polyethylene terephthalate and the deionized water and the CO2 within the reactor to a reaction temperature; and

reacting the weight ratio of the polyethylene terephthalate and the deionized water and the CO2 within the reactor for a reaction duration, converting depolymerized polyethylene terephthalate and forming a reaction product.

10. The method of claim 9 , wherein the weight ratio of the polyethylene terephthalate and the deionized (DI) water comprises 1:10, 1:15, 1:20, 1:25, and 1:30.

11. The method of claim 9 , wherein the reaction temperature comprises 160° C., 180° C., 200° C., 220° C., and 240° C.

12. The method of claim 9 , wherein the reaction time comprises 0.25 hrs, 0.5 hrs, 1 hr, 1.5 hrs, and 2.0 hrs.

13. The method of claim 9 , wherein the injection pressure comprises 700 psi.

14. The method of claim 9 , wherein the reactor comprises a supercritical high temperature reactor.

15. A method for recycling polyethylene terephthalate (PETE) by depolymerizing polyethylene terephthalate, the method comprising:

providing a reactor and reactor contents of polyethylene terephthalate and deionized (DI) water;

injecting CO2 into the reactor contents;

heating the reactor contents; and

reacting the reactor contents, depolymerizing the reacting polyethylene terephthalate to form a reaction product, wherein a yield of reaction product terephthalic acid from the depolymerizing of reacted polyethylene terephthalate from the reacting of the reactor contents with the CO2 injection is higher, than a yield of a reaction product terephthalic acid from a depolymerizing of reacted polyethylene terephthalate from a reacting of the reactor contents without the CO2 injection into the reactor contents.

16. The method of claim 15 , further comprising:

sealing the reactor contents within the reactor.

17. The method of claim 16 , further comprising:

converting polyethylene terephthalate to a liquid product and a solid product in the reactor.

18. The method of claim 16 , wherein the reacted contents comprise the reaction product of terephthalic acid in the liquid product.

19. The method of claim 16 , wherein the reacted contents comprise polyenes and benzoic acid crystals.

20. The method of claim 16 , wherein the reacted contents comprise a reaction product of ethylene glycol.

Assignments (2)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jan 25, 2024
From: FAN, MAOHONG; LU, WENYANG
To: UNIVERSITY OF WYOMING
Reel/Frame 066246/0806 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jan 25, 2024
From: ZHANG, JINWEN
To: WASHINGTON STATE UNIVERSITY
Reel/Frame 066246/0972 →
Continuity (3)
Continuation 17246204 · Apr 30, 2021
Provisional Application 63018189 · Apr 30, 2020
Related Publication 20240117140A1 · Apr 11, 2024
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