CO₂-intensified dry reforming of methane over oxygen-defective Ni-CeO₂ catalysts: Synergistic coupling with reverse water-gas shift reaction

This study investigates the performance of Ni-CeO₂ catalysts synthesized via a cellulose-assisted combustion method (CACS) for the synergistic coupling of dry reforming of methane (DRM) and the reverse water–gas shift reaction (RWGS), referred to as SCDR. Among the catalysts with varying Ni loadings, the 15 wt% Ni-CeO₂ catalyst exhibited an optimal balance of Ni dispersion and oxygen vacancy formation, achieving superior CH₄ and CO₂ conversions. In DRM reaction, catalytic activity was primarily determined by the number of Ni active sites, with higher Ni dispersion enhancing CH₄ conversion. In contrast, under SCDR conditions, catalytic performance was significantly influenced by the oxygen storage capacity (OSC), which facilitated CO₂ activation and intermediate formation. The well-dispersed Ni and strong metal-support interaction at the Ni-O-Ce interface further promoted CO₂ activation, improving sintering resistance and enabling the formation of key intermediates such as bidentate carbonates and formates. These intermediates were essential for sustaining reaction turnover, with the Ni-O-Ce interface contributing to the rapid regeneration of active sites and maintaining catalytic activity under CO₂-rich conditions. Additionally, the high CO₂ partial pressure in SCDR suppressed carbon deposition, enhancing stability and reaction rates compared to DRM.