Acid Site Engineering of Ni/BEA Zeolites Enables Efficient Upcycling of Polyolefin Plastics to Liquid Fuels

Conventional metal-zeolite catalysts often face diffusion limitations in hydrocracking polyolefin wastes due to the poor accessibility of active sites within zeolitic micropores. In this study, commercial BEA zeolite was modified through various post-synthetic treatments, followed by nickel loading via incipient wetness impregnation, to enhance both structural and acidic properties. Among them, the TEAOH-assisted hydrothermal modification (Ni/BEA-TEA) generated a hierarchical architecture with optimized Al distribution, strengthening surface acidity while preserving crystallinity. This catalyst achieved 84.5% polyethylene (PE) conversion with 89.5% selectivity toward gasoline-diesel-range hydrocarbons at 280°C. The remarkable activity enhancement is attributed to improved acid site accessibility and balanced hydrogenation-cracking synergy. This work highlights that tailoring acid-site distribution and surface structure through controlled zeolite modification provides an effective strategy for designing advanced bifunctional catalysts for efficient and selective polyolefin upcycling.