CONSTRUCTION OF THE ChCl-Zn(Ac)2 CATALYTIC SYSTEM AND OPTIMIZATION OF THE PROCESS CONDITIONS FOR DIRECT SYNTHESIS OF PLASTICIZER DOTP FROM WASTE PET VIA CATALYTIC ALCOHOLYSIS

Using waste polyethylene terephthalate (PET) as the feedstock, diisooctyl terephthalate (DOTP) was directly synthesized via alcoholysis with isooctanol (2-EH) over an environmentally friendly choline chloride-zinc acetate (the ChCl-Zn(Ac)2 catalyst)-deep eutectic solvent (DES). This approach overcame the limitations of traditional methods by offering simplicity, low cost, tunable composition, excellent environmental compatibility, and superior chemical stability. The study systematically investigated the effects of reaction temperature, catalyst dosage, molar ratio of 2-EH to PET, and reaction time on the synthesis process. Response surface methodology (RSM) was employed to optimize the process conditions, with the optimal parameters determined as follows: reaction temperature of 180 °C, catalyst dosage of 5.19%, molar ratio of 2-EH to PET of 4.89 mol mol-1, and reaction time of 87.30 min. Under these optimal conditions, PET was completely degraded, and the DOTP yield reached as high as 87.59%. The ChCl-Zn(Ac)2 catalyst exhibited stable performance, significantly enhanced both the PET degradation rate and the DOTP yield. This study provides a feasible technical solution for the efficient resource utilization of waste PET, offers a reference for developing green catalytic synthesis processes of DOTP, and expands the application potential of DES catalysts in polyester degradation.