Ternary-Active NiO-NiAl<sub>2</sub>O<sub>4</sub>-Al<sub>2</sub>O<sub>3</sub> Nanocomposite for Selective Upcycling of Polypropylene into Liquid Branched Olefins.

Cheng, Qing; Bi, Jingyou; Shan, Chun; Kong, Ge; Jiang, Yuan; Zhang, Guanyu; Liu, Hongkang; Zhang, Xin et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Chemical upcycling is an attractive platform for converting plastic waste into valuable products. Here, a tandem deconstruction-catalysis route was developed for upcycling polypropylene (PP). A ternary-active NiO-NiAl<sub>2</sub>O<sub>4</sub>-Al<sub>2</sub>O<sub>3</sub> nanocomposite was innovatively synthesized, with the NiO/NiAl<sub>2</sub>O<sub>4</sub> particle size lowering to ca. 5 nm, affording abundant active sites. Importantly, it demonstrated excellent reusability, maintaining high catalytic activity over 30 cycles with the highest liquid yield of 63.33 wt %, primarily composed of branched olefins. Particularly, it was capable of effectively upcycling real-world PP medical operating coats, achieving a narrower carbon number distribution with exceptionally high carbon selectivity of 90.18 mol % for gasoline (C<sub>4</sub>-C<sub>12</sub>)-range hydrocarbons, respectively. Additionally, <i>in situ</i> Fourier transform infrared spectroscopy characterization revealed that the ternary-active nanocomposite facilitated the activation and pre-cracking of PP chains into shorter, unsaturated oligomers, which were subsequently converted into branched olefins and aromatics. In brief, this study proposed a promising solution using a ternary-active nanocomposite to effectively upcycle PP waste.