Process for recycling polyethylene terephthalate using a gradient in impurity concentration

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.