Low-temperature hydrogen production from waste polyethylene by nonthermal plasma (NTP)-assisted catalytic pyrolysis using NiCeOx/β catalyst

Abstract

Conventional catalytic pyrolysis of waste plastics for H2 production faces challenges due to excessively high reaction temperatures. This study introduced a NiCeOx/β catalyst for low-temperature H2 production from polyethylene (PE), aiming to enhance H2 yield through nonthermal plasma (NTP) and catalytic active sites. Experimental results confirmed the efficacy of NTP in promoting collision between high-potential-energies active species and plasma-catalyst interactions, identifying acidic sites as primary catalytic active sites. Both experiments and density functional theory (DFT) calculations confirmed NiO and CeO2 particles as metallic active sites, exhibiting thermodynamic and kinetic benefits for primary products from PE pyrolysis. Under optimal conditions, the highest H2 yield and selectivity respectively reached 32.71 mmol/g and 82.10 % at a PE/(NiCeOx/β) ratio of 1:4, reaction temperature of 400 °C, and NTP discharge power of 210 W. The NiCeOx/β catalyst facilitated low-temperature pyrolysis of waste plastics, enhancing H2 selectivity and yield.