Method for the enzymatic degradation of polyethylene terephthalate

Patent metadata

Field	Value
Publication number	US-12473417-B2
Application number	US-201917291291-A
Country	US
Kind code	B2
Filing date	Nov 5, 2019
Priority date	Nov 6, 2018
Publication date	Nov 18, 2025
Grant date	Nov 18, 2025

Abstract

The present invention relates to a process for enzymatic depolymerization of polyethylene terephthalate (PET), in particular contained in a plastic material. The process according to the invention can in particular be implemented on an industrial or semi-industrial scale.

First claim

The invention claimed is:

1 . A process for enzymatic depolymerization of semi-crystalline polyethylene terephthalate (PET) comprising bringing said semi-crystalline PET into contact with an enzyme capable of depolymerizing said semi-crystalline PET, said enzyme selected from cutinases comprising an amino acid sequence having at least 75% identity with SEQ ID NO:1, and further comprising at least one mutation combination selected from: (i) F208I+D203C+S248C+Y92G, (ii) F208W+D203C+S248C+Y92G, or (iii) F208I+D203C+S248C+V170I+Y92G, corresponding to the residues of SEQ ID NO:1, wherein:
a) the semi-crystalline PET has an initial degree of crystallinity of at most 25%; b) the depolymerization step is carried out at a temperature T equal to the Tg+10° C. of said semi-crystalline PET; and c) the enzyme has a depolymerization time (tD) of the semi-crystalline PET that is less than the crystallization time (tR) of said semi-crystalline PET, wherein the time tD represents the time required for said enzyme to depolymerize at least 80% of said semi-crystalline PET at said temperature T, and the time tR represents the time required for said semi-crystalline PET to reach a degree of crystallinity of at most 35% at said temperature T.

2 . The depolymerization process as claimed in claim 1 , wherein the temperature T is between the Tg−10° C. and the Tg+5° C. of the semi-crystalline PET.

3 . The depolymerization process as claimed in claim 1 , wherein the temperature T is between 66° C. and 80° C.

4 . The depolymerization process as claimed in claim 1 , wherein the crystallization time of the semi-crystalline PET is measured prior to the depolymerization step, on a sample of said semi-crystalline PET.

5 . The depolymerization process as claimed in claim 1 , wherein the selected enzyme has a time tD less than or equal to 20 h.

6 . The depolymerization process as claimed in claim 1 , wherein the enzyme is selected from enzymes having a melting temperature (Tm) strictly higher than the temperature T.

7 . The depolymerization process as claimed in claim 1 , wherein the initial degree of crystallinity of the semi-crystalline PET is less than 20%.

8 . The depolymerization process as claimed in claim 1 , wherein the depolymerization time (tD) is between 1 h and 16 h.

9 . The depolymerization process as claimed in claim 1 , wherein the semi-crystalline PET is subjected to an amorphization step prior to the depolymerization step.

10 . The depolymerization process as claimed in claim 1 , wherein the time tD represents the time required for said enzyme to depolymerize at least 90% of said semi-crystalline PET at said temperature T, and the time tR represents the time required for said semi-crystalline PET to reach a degree of crystallinity of at most 30% at said temperature T.

11 . The depolymerization process as claimed in claim 1 , wherein:
a) the semi-crystalline PET has an initial degree of crystallinity of at most 25% and a Tg between 65° C.±1° C. and 80° C.±1° C.; b) the depolymerization step is carried out at a temperature T of 72° C.±1° C.; and c) the enzyme has a depolymerization time (tD) of the semi-crystalline PET that is less than the crystallization time (tR) of said semi-crystalline PET, wherein the time tD represents the time required for the selected enzyme to depolymerize at least 80% of said semi-crystalline PET at said temperature T, and the time tR represents the time required for said semi-crystalline PET to reach a degree of crystallinity of at most 35% at said temperature T.

12 . The depolymerization process as claimed in claim 1 , wherein:
a) a plastic material is selected from fibers and/or fiber and/or textile waste comprising semi-crystalline PET with an initial degree of crystallinity of at most 25% and a Tg between 60° C.±1° C. and 75° C.±1° C.; b) the depolymerization step is carried out at a temperature T of 65° C.±1° C.; and c) the enzyme capable of degrading semi-crystalline PET has a depolymerization time (tD) of the semi-crystalline PET that is less than the crystallization time (tR) of said semi-crystalline PET, wherein the time tD represents the time required for the selected enzyme to depolymerize at least 80% of said semi-crystalline PET at said temperature T, and the time tR represents the time required for said semi-crystalline PET to reach a degree of crystallinity of at most 35% at said temperature T.

13 . The depolymerization process as claimed in claim 1 , wherein the temperature T is between 68° C. and 73° C.

14 . The depolymerization process as claimed in claim 1 , wherein the depolymerization time (tD) is between 1 h and 10 h.

15 . The depolymerization process as claimed in claim 1 , wherein the cutinase has at least 75% identity with SEQ ID NO:1 and comprises the mutation combination F208I+D203C+S248C+Y92G, corresponding to the residues of SEQ ID NO:1.

16 . The depolymerization process as claimed in claim 1 , wherein the cutinase has at least 75% identity with SEQ ID NO:1 and comprises the mutation combination F208W+D203C+S248C+Y92G, corresponding to the residues of SEQ ID NO: 1.

17 . The depolymerization process as claimed in claim 1 , wherein the cutinase has at least 75% identity with SEQ ID NO:1 and comprises the mutation combination selected from: (i) F208I+D203C+S248C+Y92G, or (iii) F208I+D203C+S248C+V170I+Y92G, corresponding to the residues of SEQ ID NO:1.

Assignees

• Carbios

Inventors

• Marty Alain

Classifications

• C12Y301/01074

  Cutinase (3.1.1.74) · CPC title

• C12N9/18

  Carboxylic ester hydrolases {(3.1.1)} · CPC title

• C08J2367/02

  Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) · CPC title

• Y02W30/62

  Plastics recycling; Rubber recycling · CPC title

• C08J11/105 Primary

  by treatment with enzymes · CPC title