Sustainable Hydrogen Production from Waste Plastics via Staged Chemical Looping Gasification with Iron-based Oxygen Carrier

Thermo-chemical conversion of waste plastics offers a sustainable strategy for integrated waste management and clean energy generation. To address the challenges of low gas yield and rapid catalyst deactivation due to coking in conventional gasification processes, an innovative three-stage chemical looping gasification (CLG) system specifically designed for enhanced hydrogen-rich syngas production was proposed in this work. A comparative analysis between conventional gasification and the staged CLG system were firstly conducted, coupled with online gas analysis for mechanistic elucidation. The influence of Fe/Al molar ratios in oxygen carriers and their cyclic stability were systematically examined through multicycle experiments. Results showed that the three-stage CLG in the presence of Fe1Al2 demonstrated exceptional performance, achieving 95.23 mmol/gplastic of H2 and 129.89 mmol/gplastic of syngas respectively, representing 1.32-fold enhancement over conventional method. And the increased H2/CO ratio (2.68-2.75) reflected better syngas quality via water-gas shift. Remarkably, the oxygen carrier maintained nearly 100% of its initial activity after 7 redox cycles, attributed to the incorporation of Al2O3 effectively mitigating sintering and phase segregation through metal-support interactions. These findings establish a three-stage CLG configuration with Fe-Al oxygen carriers as an efficient platform for efficient hydrogen production from waste plastics, contributing to sustainable waste valorisation and carbon-neutral energy systems.