# US 12,595,352 B2 · Process for recycling polyethylene terephthalate using selected temperature range for oligomer processing

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- Number: US 12,595,352 B2
- Document ID: US12595352B2
- Status: Granted
- Kind: B2
- Application number: 18/857,362
- Filed: 2023-09-19
- Published: 2025-05-29
- Granted: 2026-04-07
- Earliest claimed: 2022-09-20
- Assignees: Revalyu Resources GmbH
- Applicants: Revalyu Resources GmbH
- Inventors: Suresh L. Makhija; Dhanvant Yeola; Christian Neumann
- Web page: https://patentgrep.com/patent/US12595352B2

## CPC

- C08J 11/10: by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation (depolymerisation to the original monomer C07)
- C08J 11/24: containing hydroxyl groups
- C08J 11/18: by treatment with organic material
- C08J 2367/00: Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J 2367/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence)
- C08J 2467/00: Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J 2467/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds (C08J2467/06 takes precedence)
- Y02W 30/62: Plastics recycling; Rubber recycling
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

One aspect is a method for producing a first intermediate product. A feedstock is provided that comprises a first polyester. The first polyester is contacted with a further organic compound in a volume section V3 to obtain a further initial mixture. A weight average molar mass of the first polyester is reduced in the volume section V3 to obtain a first intermediate mixture. The first intermediate mixture comprises a first intermediate product and; the further organic compound. First particulated material is added to the first intermediate mixture in a volume section V4. A temperature of the first intermediate mixture in the volume section V4 is in the range of 160° C. to 230° C.

## Claims

### Claim 1

A method for producing a first intermediate product, comprising the steps of
a. providing a feedstock that comprises a first polyester;
b. contacting the first polyester with a further organic compound in a volume section V3, to obtain a further initial mixture;
c. reducing a weight average molar mass of the first polyester in the volume section V3, to obtain a first intermediate mixture, wherein the first intermediate mixture comprises
i. a first intermediate product that has an intrinsic viscosity in the range of 0.010 dL/g to 0.120 dL/g,
ii. the further organic compound;
d. adding first particulated material to the first intermediate mixture in a volume section V4;
e. transporting the first intermediate mixture to a filtering means;
f. at least partially removing at least one impurity from the first intermediate mixture using the filtering means;
wherein
a temperature of the first intermediate mixture in the volume section V4 is in the range of 170° C. to 220° C., and wherein at least 40 wt-% of the first intermediate product is in the form of oligomers that have in the range of 2 to 35 repeating units, and wherein the first particulated material is diatomaceous earth,
with the intrinsic viscosity, the wt-% of the first intermediate product in the form of oligomers, and the temperature in the volume section V4 determined according to the methods described herein.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the first polyester is selected from the group consisting of a polyethylene terephthalate, a polybutylene terephthalate, a polylactide, a polytrimethylene terephthalate, a polyethylene naphthalate, a polycarbonate, a polyester carbonate, a polyarylate, a polyester resin, and a combination of two or more thereof.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the further organic compound has at least one or all of the following properties:
a. comprises at least two hydroxyl groups;
b. a molar mass of at least 60 g/mol;
c. a boiling point of at least 192° C.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the temperature of the further initial mixture in the volume section V3 is in the range of 180° C. to 220° C., with the temperature determined according to the method described herein.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the first intermediate mixture comprises at least 70 wt-% of the first intermediate product, with the wt-% determined according to the method described herein.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the method further comprises the step of at least partially removing at least one impurity from the first intermediate mixture.