Long-Chain Branched α-Alkenes from Plastic Upcycling Using Mo ₂ C–Zn Nanoclusters Embedded on Hierarchical Porous Carbon

The use of plastics has led to widespread waste and severe environmental impacts. Herein, a decomposition-catalysis upcycling strategy using M-Zn codoped hierarchical porous carbon (M-Zn/HPC) was proposed for polypropylene (PP) upcycling into highly valuable long-chain branched α-alkenes. Zn/HPC-II, synthesized via a two-step carbothermal reduction, exhibited excellent catalytic activity for the conversion of PP to C4-C18 liquid hydrocarbons. Furthermore, bimetallic Mo₂C-Zn/HPC exhibited the best catalytic performance, achieving a liquid yield of 887.3 mL/kg_PP and 54.5 Cmol % selectivity for long-chain branched α-alkenes. The catalytic mechanism involves thermal degradation of PP via free radical scission, followed by reforming on Mo₂C-Zn/HPC, where Mo₂C with lattice distortions facilitated C-H bond activation and synergized with Zn/HPC acid sites to β-scission and related reactions, efficiently producing long-chain branched α-alkenes. The robust stability of Mo₂C-Zn/HPC was further confirmed using real-life PP plastic wastes. Overall, this study presents a promising strategy for converting PP waste into high-value long-chain branched α-alkenes.