Design of Catalysts for Glycolysis of Polyethylene Terephthalate from Spent Batteries

Abstract

Mn doped ZnO powders were obtained by mechanical milling, a simple and economic method, using recovered oxides from batteries waste as starting materials. Structural and morphological properties of the solids were investigated by powder X-ray diffraction, X-ray absorption spectroscopy and scanning and transmission electron microscopy. It is confirmed that Mn atoms are incorporated into the ZnO lattice with a mixed oxidation state, Mn2+ and Mn3+. A red shift in the absorption spectra from DRS-UV-visible spectroscopy due to Mn doping in ZnO was observed. These results are attributed to the presence of new electronic states as a consequence of Mn doping. The catalytic activity of the solids in the glycolysis reaction of PET was evaluated by the yield to the PET monomer, bis(2-hydroxyethyl) terephthalate (BHET), which reached 80% for the sample with highest Mn concentration. Mn doping enhances the BHET yield revealing the crucial role played by doped atoms interaction and vacancy defects. This work shows how it is possible to obtain new materials from waste that allow closing the life cycle of batteries and plastic bottle waste.