In-situ hydrogen generation via water-gas shift reaction over Ni-Fe3O4/USY: A sustainable pathway for efficient polypropylene hydrogenolysis

The escalating crisis of global plastic pollution underscores an urgent need for truly sustainable and closed-loop technological solutions. While chemical recycling presents a promising route, its current reliance on fossil-derived hydrogen fundamentally undermines the process's environmental rationale. Herein, an innovative cascade catalytic system is introduced that directly addresses this challenge by employing the water-gas shift reaction (WGSR) as an in-situ hydrogen source. This integrated strategy enables the efficient conversion of polypropylene (PP) waste into high-value liquid fuels (C 5 -C 22 ). The process is driven by a rationally designed bifunctional catalyst, Ni-Fe 3 O 4 /USY. The reducible Fe 3 O 4 continuously generates active hydrogen species through the WGSR, while Ni finely tunes the redox properties required for CO activation. Concurrently, the acidic sites of the USY zeolite facilitate the selective cleavage of C-C bonds in the polymer chain. The results show that the well-designed tandem reaction achieves >99% conversion of post-consumer PP waste and a remarkably high liquid fuel yield of 83.2% under relatively mild conditions (340 °C). This study establishes a green and intensified pathway for plastic valorization, fundamentally circumventing the dependency on external fossil-based hydrogen and paving the way for more sustainable chemical recycling paradigms.