The global plastic waste crisis, especially from poly(ethylene terephthalate) (PET), demands urgent sustainable solutions. Using green hydrogen from renewable sources to hydrogenolyze PET shows promise for producing key industrial commodity chemicals including para-xylene (PX) and ethylene glycol (EG), which are essential for the production of polyester, antifreeze, and other chemicals. However, developing scalable, cost-effective, and atom-efficient processes for synthesizing drop-in chemicals via PET hydrogenolysis remains challenging. This study presents a catalytic system with a ternary Cu-Zr-Al inverse catalyst (Al-ZrO2/Cu) that operates at 180 °C and 6 MPa H2. It nearly quantitatively converts PET into PX (>99% yield) and EG (92% yield). The catalyst, with modulated surface acidity and abundant oxygen vacancies, selectively activates the benzylic C-O bonds in PET for efficient hydrogenolytic depolymerization. In hexafluoroisopropanol (HFIP)-mediated continuous-flow reactions, the process generates a spontaneously biphasic PX/EG mixture, simplifying separation. Mechanistic studies reveal that interfacial oxygen vacancies and Lewis acid centers synergistically activate H* species and macromolecular ester bonds. This work offers a strategic approach to interfacial catalyst design, providing a technically and economically feasible way to transform waste commodity plastics into high-demand bulk chemicals. By combining scalable catalysis with circular economy concepts, it enhances plastic waste valorization and delivers sustainable, large-scale solutions for global plastic pollution.
Sun et al. (Fri,) studied this question.