Regenerable Ni-Substituted Perovskite Catalysts for CO2 Reforming of Plastic Pyrolysis Gas: Mechanistic Insights via Lattice Oxygen Restoration

Abstract

The synergistic valorization of CO2 and waste plastics offers a sustainable route for simultaneous carbon utilization and plastic upcycling, yet catalyst deactivation remains a major challenge. Herein, LaFe1–xNixO3 perovskites were developed for CO2-assisted reforming of plastic pyrolysis gas at 900 °C. LaFe0.5Ni0.5O3 exhibited optimal performance, achieving a syngas yield of 170.84 mmol gpp–1, a specific CO2 valorization of 38.60 mmol gpp–1, and an apparent carbon conversion of 149.85%. Structural characterization revealed that the superior activity originated from the synergistic interaction of in situ exsolved Fe–Ni alloy nanoparticles, oxygen vacancies, and lattice oxygen. Cycling experiments demonstrated that catalyst deactivation is primarily caused by progressive depletion of the lattice oxygen reservoir, whereas air regeneration restores both the perovskite structure and lattice oxygen, maintaining stable catalytic performance over ten regeneration cycles. Furthermore, the catalyst exhibited comparable syngas production from a mixed real-polyolefin feedstock, demonstrating its practical applicability. These findings establish the central role of lattice oxygen dynamics in catalyst activity, deactivation, and regeneration, providing mechanistic guidance for designing regenerable catalysts for CO2-assisted plastic waste valorization.