# US 12,600,836 B2 · Process for recycling polyethylene terephthalate using a gradient in impurity concentration > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,600,836 B2 - Document ID: US12600836B2 - Status: Granted - Kind: B2 - Application number: 18/857,358 - Filed: 2023-09-19 - Published: 2025-05-29 - Granted: 2026-04-14 - 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/US12600836B2 ## 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 amount of a first organic compound in a volume section V2. At least one impurity is present in the volume section V2, and the volume section V2 has a first zone and a further zone. 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. A relative ratio of a particle count per area of the at least one impurity in the first zone to a particle count per area of the at least one impurity in the further zone is equal to or greater than 10. ## 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 amount of a first organic compound in a volume section V2, wherein i. at least one impurity is present in the volume section V2, ii. the volume section V2 has a first zone and a further zone; iii. the further zone is downstream the first zone, iv. a mass ratio of the first polyester to a first organic compound in the first zone is smaller than a mass ratio of the first polyester to a first organic compound in the further zone, and v. a transport direction of the first polyester in the volume section V2 is from the first zone to the further zone; c. reducing a weight average molar mass of the first polyester in the volume section V2, wherein after the reduction step has been completed, the first polyester has an intrinsic viscosity in the range of 0.10 dL/g to 0.45 dL/g; d. transporting the first polyester to a volume section V3; e. contacting the first polyester with a further organic compound in the volume section V3, to obtain a further initial mixture; f. reducing the 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 0.090 dL/g, ii. the further organic compound; wherein a relative ratio of a particle count per area of the at least one impurity in the first zone to a particle count per area of the at least one impurity in the further zone is equal to or greater than 10 and equal to or less than 1000, with the intrinsic viscosity and the relative ratio of the particle count per area of the at least one impurity determined according to the methods described herein. ### Claim 2 (depends on 1) The method according to claim 1, further comprising the step of contacting the feedstock with a first amount of a first organic compound in a volume section V1 to obtain a first initial mixture, wherein the first amount is in the form of a liquid. ### Claim 3 (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 4 (depends on 1) The method according to claim 1, wherein the feedstock further comprises the at least one impurity. ### Claim 5 (depends on 4) The method according to claim 4, wherein the at least one impurity in the feedstock is in the range of 10 ppm wt to 10000 ppm wt, where the wt is based on a total weight of the feedstock, with the wt ppm determined according to the method described herein. ### Claim 6 (depends on 1) The method according to claim 1, wherein the first 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 7 (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 8 (depends on 1) The method according to claim 1, 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, with the wt-% determined according to the method described herein.