Chemo-catalytic recycling of PET waste: Progress and prospects for circular economy and valorization

Abstract

Polyethylene terephthalate (PET), a non-biodegradable single-use plastic, is emerging as a significant environmental issue. The extensive utilization of PET in packaging, especially for disposable products like beverage bottles and food containers, has led to a growing build-up of its waste in landfills, rivers, and oceans, contaminating the ecosystem and eventually infiltrating the global food chain. The limitation of existing physical degradation methods has spurred interest in chemical recycling as a promising alternative for managing PET waste. Traditional, non-catalytic methods for depolymerizing PET are sluggish, energy-intensive, and require high temperatures and/or pressures. However, recent breakthroughs in material chemistry have led to the introduction of innovative strategies that can significantly enhance PET degradation under relatively mild reaction conditions. This review highlights the most recent advances in the development of efficient catalysts such as biomass-waste, mixed metals, zeolites, metal-organic framework, nanomaterials, organocatalysts, and ionic liquids for the processes of glycolysis, methanolysis, and reductive depolymerization. Each section provided a brief overview of the catalyst preparation, functionality, active sites, and reaction mechanism.