Synergistic pore-acidity engineering of hierarchical ZSM-5 for hydrogen-free upcycling of Polyethylene to C8–C12 Methylated Aromatics

Transforming polyethylene (PE) into high-value chemicals is often hindered by diffusion barriers. Here, we report a hydrogen-free strategy using pore-engineered hierarchical ZSM-5. By tuning desilication, we identified a critical pore–acidity synergy at an optimal Vmeso/Vmicro ratio of ~2.7 within this specific low Si/Al (25~50) framework. The optimal catalyst achieved near-complete conversion (98.8%) and an aromatic yield of 37.4% at a mild temperature of 280 °C. In-situ FTIR and molecular dynamics simulations reveal that this synergy facilitates a cascade reaction mechanism. The introduced mesoporosity enhances the effective diffusion coefficient of C10 intermediates by an order of magnitude (from 0.1 ×10−9 m2s−1 to 2.2×10−9 m2s−1), thus enabling rapid turnover and suppressing over-cracking. The hierarchical catalyst (Hier-Z5-43) demonstrated exceptional stability and versatility for real-world plastic upcycling. Techno-economic and life cycle analyses confirm substantial advantages, reducing energy consumption by 10.9 MJ/kg and decreasing global warming potential by >55% compared to conventional fossil-based routes. This study highlights the importance of synergistically optimizing pore structure and acidity to enhance catalytic performance in polyolefin upcycling.