Low-temperature catalytic CO₂ methanation over nickel supported on praseodymium oxide

Nickel (Ni)-based catalysts are widely used for CO₂ methanation due to their cost-effectiveness compared to noble metals and high efficiency. However, their catalytic performance at low temperatures remains a significant challenge, primarily due to the limited activation of CO₂. This study reveals that the Ni supported on praseodymium oxide (PrO_x) significantly enhanced low-temperature CO₂ methanation activity. This enhancement was primarily attributed to the dual role of PrO_x: promoting CO₂ activation and modifying the reducibility of Ni active sites. PrO_x facilitated the formation of oxygen vacancies (O_v) through the valence state transition (Pr³⁺ ↔ Pr⁴⁺), providing electron donor sites for direct CO₂ dissociation (CO₂ → CO + O*). Furthermore, metal-support interaction (MSI) between Ni and PrO_x enhanced the reducibility of Ni²⁺ to Ni⁰_, inducing a higher density of hydrogen activation sites for the hydrogenation of CO₂. The integration of these properties induced a high efficiency of the CO₂ methanation pathway by enhancing reactant activation efficiency. These findings demonstrate that the synergistic interaction between Ni and PrO_x enhances CO₂ methanation by simultaneously improving Ni site reducibility and providing abundant oxygen vacancies for CO₂ activation, indicating PrO_x as a highly effective support material for low-temperature CO₂ methanation catalysts.