Method and system for efficient catalyst-free alcoholysis of waste polyester

A method for efficient catalyst-free alcoholysis of waste polyester, the method comprising the steps of:

• performing a pre-alcoholysis reaction by contacting molten waste polyester material with a first quantity of an alcoholytic agent within a screw processing unit, wherein the mass ratio of said first quantity of the alcoholytic agent to the molten waste polyester material is between 0.2% and 10%, said contacting being performed under conditions sufficient to yield a pre-alcoholized material having an intrinsic viscosity between 0.1 dL/g and 0.5 dL/g;
• filtering the pre-alcoholized material to obtain a fine-filtered pre-alcoholized product;
• and
• performing a deep alcoholysis reaction by contacting the fine-filtered pre-alcoholized product with a second quantity of an alcoholizer within an alcoholysis reactor separate from the screw processing unit, wherein the mass ratio of the total alcoholizer present during said deep alcoholysis reaction relative to the mass of the fine-filtered pre-alcoholized product is between 1:0.1 and 1:0.6, and wherein said deep alcoholysis reaction is conducted under catalyst-free conditions to obtain depolymerized products comprising corresponding monomers and/or intermediates.