PET depolimerization in supercritical ethanol conditions catalysed by nanoparticles of metal oxides

The depolymerization of the PET in supercritical conditions using ethanol and catalyzed by cobalt and nickel oxides was enough for the recovery of the DET monomer, allowing yields close to 100 % depolymerization. The formation of DET in the depolymerization process was characterized by 1H-NMR, DSC, FTIR, SEM, and HPLC. Cobalt oxide and nickel oxide were obtained through the Pechini method and characterized using DRX, SEM, and TEM. A factorial design 22 with a duplicate center point was applied to evaluate the reaction time and amount of the catalyst effects on yield. Through analysis of response surface methodology (RSM), the highest degree of PET conversion (%) was obtained in 90 min reaction time and a smaller amount of catalyst (10 mg) through analysis of response surface contour. The smaller quantity of catalyst was sufficient to accelerate the process of depolymerization reaching almost 100 % yield, obtaining the monomer DET as the main product.