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

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; Mw = 100–200 kDa). We report Ru–Ni alloy nanoparticles (3–4 nm) supported on titania that yield up to 55% liquid C6–C45 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 CO2 emissions even when using green H2. Furthermore, within the Plastic-to-X framework, we identify a minimum average chain length threshold of C11 for product distributions as a critical design metric to reconcile environmental and economic objectives.