Solvent‐ and Hydrogen‐Free Upcycling of Polystyrene by Layered Double Oxides

ABSTRACT Chemical upcycling of plastic waste into value‐added feedstocks holds great promise for advancing the circular economy, while confronting formidable challenges. Herein, we report a cost‐effective catalyst MgAl‐layered double oxide (MgAl‐LDO) for upcycling polystyrene (PS) into liquid fuel substitute components with rich styrene under solvent‐ and H ₂ ‐free conditions. The operando characterizations and theoretical simulations demonstrate that the MgAl‐LDO, featuring rich basic sites (Mg─O), is favorable for efficient activation of C─H bonds and selective cleavage of C(sp ³ )‐C(sp ³ ) bonds. In particular, MgO in MgAl‐LDO affords a low barrier for the rate‐determining step for the formation of styrene while simultaneously suppressing the side reaction of further hydrogenation. As a result, the MgAl‐LDO achieves a liquid fuel yield of 59.5% with a styrene selectivity of 70.9% at 280°C. Further, the obtained styrene monomer was copolymerized with methyl methacrylate (MMA) to prepare high value‐added MMA‐styrene copolymer, which offers pivotal insights into advanced chemical upcycling strategies, facilitating the transition to a sustainable plastics economy and the reduction of environmental impacts.