Polyethylene hydrogenolysis to liquid products over bimetallic catalysts with favorable environmental footprint and economics.

Nogueroles-Langa, Iris; Ge, Yuzhen; Salah, Cecilia; Jaydev, Shibashish D; Morales-Vidal, Jordi; Berman, Pol S; Eliasson, Henrik; Erni, Rolf et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

Assessing the sustainability of plastic chemical recycling requires realistic feedstocks and catalysts designed within sustainability-led frameworks (Plastic-to-X). We link catalyst design and systems analysis to study hydrogenolysis of high-density polyethylene (virgin and bottle caps; M<sub>w</sub> = 100-200 kDa). We report Ru-Ni alloy nanoparticles (3-4 nm) supported on titania that yield up to 55% liquid C<sub>6</sub>-C<sub>45</sub> products under optimized conditions, whereas monometallic Ru produces virtually no liquids  Operando spectroscopy and simulations reveal structure sensitivity: backbone scission follows dehydrogenation and hydrogenation cycles at defective alloy sites formed in situ. Integrating these mechanistic insights with life cycle and techno-economic analyses indicates profitable processing of plastic caps over the optimal catalyst (2.5 wt% Ru, 5 wt% Ni) with substantially lower CO<sub>2</sub> emissions even when using green H<sub>2</sub>. Furthermore, within the Plastic-to-X framework, we identify a minimum average chain length threshold of C<sub>11</sub> for product distributions as a  critical design  metric to reconcile environmental and economic objectives.