Enzymatic process for depolymerization of post-consumer poly(ethylene terephthalate) by a glycolysis reaction, process for recycling post-consumer poly(ethylene terephthalate), and recycled poly(ethylene terephthalate)

Patent metadata

Field	Value
Publication number	US-11359068-B2
Application number	US-201716468582-A
Country	US
Kind code	B2
Filing date	Sep 14, 2017
Priority date	Sep 14, 2017
Publication date	Jun 14, 2022
Grant date	Jun 14, 2022

Abstract

The present invention relates to an enzymatic process for depolymerization of post-consumer poly(ethylene terephthalate) by a glycolysis reaction. This invention also relates to a process for recycling post-consumer poly(ethylene terephthalate) and to the recycled poly(ethylene terephthalate) obtained by said process.

First claim

The invention claimed is:

1. Enzymatic process for depolymerization of post-consumer poly(ethylene terephthalate) by a glycolysis reaction, comprising steps of:
a) adding poly(ethylene terephthalate) and ethylene glycol to a stirred tank reactor;
b) adjusting the temperature to a value between 20 and 100° C. and stirring at a speed between 20 and 300 rpm; and
c) adding a charge of a catalyst between 0.01 to 1.0 g/gPET to the reactor, wherein the catalyst comprises one or more enzymes of the cutinase, esterase or lipase type,
wherein, after a period of time of from 2 to 30 days, a final stream comprising terephthalic acid (TPA), mono-hydroxyethylene terephthalate (MHET) and bis-hydroxyethylene terephthalate (BHET) is obtained, which comprises 30 to 95 mol % of BHET based on the total of final products of the reaction.

2. Process according to claim 1 , wherein the process is carried out in batch mode in a reactor of the CSTR type.

3. Process according to claim 1 , additionally comprising a pre-treatment step before step a).

4. Process according to claim 3 , wherein the pre-treatment step comprises washing with non-ionic surfactant or soaking with ethylene glycol, or mixtures thereof with other alcohols.

5. Process for according to claim 1 , wherein the temperature in step b) is between 30 and 90° C.

6. Process according to claim 1 , wherein the one or more enzymes of the cutinase, esterase and lipase type are selected from a cutinase from Humicola insolens expressed in Aspergillus ; and CALB, lipase B from Candida antarctica.

7. Process for recycling post-consumer poly(ethylene terephthalate), comprising a step of
using the final stream comprising 30 to 95 mol % of bis-hydroxyethylene terephthalate (BHET) obtained in step c) of the enzymatic process for depolymerization of PET, as defined in claim 1 , in the repolymerization of a recycled poly(ethylene terephthalate).

8. Recycled poly(ethylene terephthalate), characterized in that it is obtained by the process as defined in claim 7 .

Assignees

• Petroleo Brasileiro S A —Petrobras

Inventors

• De Castro Aline Machado
• De Oliveira Adriano Carniel
• Valoni Erika De Araújo
• Teixeira Danielle Altomari
• Da Motta Cesar Rezende

Classifications

• C08J11/105 Primary

  by treatment with enzymes · CPC title

• C08J2367/02

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

• C12N9/18

  Carboxylic ester hydrolases {(3.1.1)} · CPC title

• C12Y301/01003

  Triacylglycerol lipase (3.1.1.3) · CPC title

• C08J11/24 Primary

  containing hydroxyl groups · CPC title