CO₂ Driven Soot Oxidation via Reverse Boudouard Reaction over Reducible Catalyst: A Sustainable Pathway for Catalyst Regeneration

Under inert N₂ atmosphere, where lattice oxygen acts as the sole oxidant, the superior reducibility of Ce_0.9Ni_0.1O_2−δ translates directly into a 75% higher soot conversion compared to pristine CeO₂ at 800 °C, producing CO as the dominant product. Post-reaction XPS confirms a marked drop in Ce⁴⁺ content and a surge in oxygen vacancy concentration, providing unambiguous spectroscopic evidence for lattice oxygen consumption via the Mars–van Krevelen mechanism.

When CO₂ is introduced as oxidant, a remarkable inversion occurs: both catalysts now achieve complete soot oxidation with near-identical light–off profiles, as gas-phase CO₂ saturation overrides differences in surface basicity and CO₂ adsorption capacity. Crucially, post-reaction XPS under CO₂ atmosphere reveals a decrease in oxygen vacancy concentration  the fingerprint of vacancy replenishment through CO₂ dissociation and catalyst self-regeneration.

This work opens a tangible pathway for deploying CeO₂-based materials as catalytic additives for CO₂-driven regeneration in fluid catalytic cracking and related refinery processes, contributing to both carbon utilization and long-term process sustainability.