Co‐Pyrolysis of Waste Biomass and Plastics Over Hematite Catalyst for High‐Yield Hydrogen Production: Product Distribution and Reaction Mechanism

ABSTRACT The co‐pyrolysis of biomass and plastic waste presents a promising route for sustainable hydrogen‐rich syngas and liquid fuel production, yet the development of low‐cost and stable catalysts remains a challenge. In this study, hematite‐rich mining tailings CT1 are employed as a catalyst in the co‐pyrolysis of wheat straw (WS) and polyethylene (PE) to investigate synergistic effects on product distribution and reaction mechanisms. Results show that CT1 significantly enhances H ₂ purity, up to 96.76 vol% at 75% PE, and completely suppresses H ₂ S and heavy hydrocarbons (C ₆₊ ). The catalyst also directs liquid product selectivity toward middle‐chain hydrocarbons, achieving over 60% selectivity at 50% PE, suitable for biodiesel and aviation fuel applications. Catalyst characterization reveals that Fe species dynamically evolve under different WS/PE ratios, influencing dehydrogenation, cracking, and deoxygenation pathways. A synergistic mechanism is proposed, wherein PE acts as a hydrogen donor, WS provides the carbon skeleton, and CT1 facilitates selective cracking and desulfurization. This work establishes a novel “waste‐to‐resource” strategy using iron tailings as a synergistic catalyst, enabling high‐value conversion of solid wastes into clean energy and chemicals.