Challenges and opportunities in catalytic hydrogenolysis of oxygenated plastics waste: polyesters, polycarbonates, and epoxy resins†

Abstract

This review comprehensively explores various homogeneous and heterogeneous catalytic systems for the hydrogenolysis of oxygenated plastic waste (OXPs), presenting an adaptable solution to plastic pollution and generating valuable feedstock. Research demonstrates enhanced hydrogenolysis efficiency with reduced energy consumption, yielding alcohols, alkanes, alkenes, and aromatics. The effectiveness of depolymerization and the product distribution are influenced by factors such as solvents, ligands, metals, catalyst support, and reaction conditions. Scaling up these processes remains challenging, highlighting the need for non-toxic, highly active catalysts. Promising homogeneous catalysts, such as Ru(triphos-Xyl), and heterogeneous catalysts, such as Ru/Nb₂O₅, show potential in OXP depolymerization but face cost-related scalability issues. Homogeneous catalysts encounter commercialization obstacles due to harsh reaction conditions and difficulties in product separation, whereas heterogeneous catalysts like Ru/Nb₂O₅ provide effectiveness and stability with easier product separation. Nonetheless, challenges in scaling up, cost reduction, and catalyst reusability persist. Achieving economic viability is crucial for the commercialization of OXP hydrogenolysis and the reduction of plastic waste. The review emphasizes the shortage of depolymerization facilities for polyesters like poly(ethylene terephthalate) (PET), poly(bisphenol A carbonate) (BPA-PC), and epoxy resins (EP). It addresses recycling process challenges, focusing on sorting and supply chain issues, and identifies specific difficulties in recycling BPA-PC, PET, and EP materials, proposing chemical recycling as a viable solution to improve economic competitiveness and environmental sustainability.