Oxidative Sintering Behavior of Ni-Based Catalysts exemplified by CO₂ Methanation Reaction

The extensive combustion of fossil fuels has resulted in a substantial increase in CO₂ emissions, intensifying the greenhouse effect and accelerating climate change. In this context, CO₂ hydrogenation has emerged as a highly promising strategy for both mitigating emissions and enabling carbon recycling within a sustainable energy future. When combined with hydrogen produced from renewable energy sources (e.g., wind and solar), the Sabatier reaction (CO₂ + 4H₂ ⇌ CH₄ + 2H₂O) provides an attractive pathway for renewable energy storage and transport in the form of methane, under the widely recognized Power-to-Gas (P2G) concept. The reaction is an exothermic process thermodynamically favored at high pressures and relatively low temperatures and can be described as the sequential combination of the Reverse Water–Gas Shift reaction followed by CO methanation. Efficient implementation of this process requires the development of highly active, selective, and thermally stable supported catalysts. Both noble metals (Ru, Rh, Pt, Pd, Ir) and non-precious metals (Ni, Fe, Co) have been investigated as active phases, with Ni-based catalysts attracting particular interest due to their low cost and natural abundance combined with high activity.
In the present work, the thermocatalytic CO₂ hydrogenation is investigated over Ni catalysts supported on ceria nanorods (CeO₂-NRs), with emphasis on optimizing catalytic activity, long-term stability, and resistance to oxidative thermal aging in comparison with conventional Ni/Al₂O₃ systems. The unique physicochemical properties of CeO₂-NRs —such as high oxygen storage capacity (OSC), enhanced lattice oxygen mobility, abundant oxygen vacancies, and strong metal–support interactions— render it a highly promising support for improving catalyst durability and mitigating sintering phenomena under demanding reaction conditions.