Integrated Chemical Upcycling of Poly(ethylene terephthalate) Waste to Multiple Value-Added Products Catalyzed by Ni<sub>2</sub>P Supported on SiO<sub>2</sub>: From Trash-to-Treasure
Devendra Sharma, Priyanka Choudhary, Sahil Kumar, Venkata Krishnan
Abstract
The indispensable use of poly(ethylene terephthalate) (PET) raises environmental concerns due to its massive accumulation in the environment. The chemical upcycling of PET offers an attractive route for the conversion of PET waste to valuable compounds. Herein, a highly effective Ni 2 P-SiO 2 catalyst was synthesized for the glycolysis of real PET waste bottles into bis(2-hydroxyethyl) terephthalate (BHET) using biomass-derived ethylene glycol. The developed Ni 2 P-SiO 2 catalyst exhibits an excellent catalytic efficiency and high BHET yields. A thorough optimization of the reaction conditions for PET glycolysis was performed to achieve maximal product yields under optimal reaction conditions using a Ni 2 P-SiO 2 catalyst. To assess environmental sustainability, green chemistry metrics and life cycle assessment (LCA) were carried out, which highlighted the advantages of the developed reaction protocol over traditional PET disposal methods. In addition, the obtained BHET monomers were subjected to hydrolysis to form terephthalic acid (TPA), which was further converted to terephthaloyl dichloride (TCL), an important value-added product. This open-loop integrated chemical upcycling process involving the conversion of PET waste bottles to multiple value-added products using a Ni 2 P-SiO 2 catalyst has the potential to tackle the ever-increasing plastic waste problem.