Upcycling of Polycaprolactone via Nonthermal Plasma-Enhanced Catalytic In Situ Hydrogenolysis at Ambient Pressure

Chemical recycling of plastics is typically hampered by energy-intensive processes requiring harsh conditions. Here, we report an electrified non-thermal plasma (NTP) catalysis strategy for the selective hydrogenolysis of polycaprolactone (PCL) into valuable caprolactones at ambient pressure and without solvents. By replacing high-pressure H₂ and noble-metal catalysts with an atmospheric methane plasma over a Ni/HY catalyst, this approach achieves complete PCL conversion and a remarkable 93.1% yield of caprolactones at 150°C utilizing solely plasma-generated heat. In situ hydrogen radicals provided by the plasma and Ni sites regenerate Brønsted acid sites, driving the selective dissociation of the PCL alkoxy bond and enabling the preferential formation of γ-caprolactone (γ-CL) both kinetically and thermodynamically at low temperatures. Simultaneously, plasma polarization promotes electron redistribution between HY and PCL, significantly lowering the dissociation energy barrier of PCL. Compared with thermal catalysis at 200°C, synergistic plasma catalysis reduces the PCL activation energy barrier from 2.29 to 1.71 eV and increases the PCL conversion by 8.77-fold. We further demonstrate the scalability of this process by operating a 100 g batch system powered by photovoltaics. This work establishes a synergistic pathway integrating methane cracking with waste plastic upcycling, offering a practical route for closed-loop polymer upcycling.