Regulating Surficial and Interfacial Active Sites over Ce-Doped Alumina-Supported Ni Catalysts To Boost Low-Temperature CO₂ Methanation

Presently, low-temperature methanation with high CO₂ conversion levels at atmospheric pressure possesses significant energy efficiency and economic advantages. However, developing stable and high-performance non-noble-metal catalysts for low-temperature CO₂ methanation remains a formidable challenge. Herein, a novel strategy for the fabrication of cerium-doped alumina-supported Ni catalysts was developed via a facile one-step coprecipitation approach facilitated by a microliquid-film reactor. The as-constructed Ni/Ce–Al₂O₃ catalyst featuring a Ce/(Ce + Al) molar ratio of 1:10 exhibited excellent low-temperature CO₂ methanation activity, with ∼82% CO₂ conversion and 100% methane selectivity at 250 °C and atmospheric pressure, as well as an extremely high methane production rate of 5.48 g_CH4·g_cat^–1·h^–1, suppressing those over most previously reported Ni-based catalysts. It was revealed that the introduction of a small amount of Ce favored the formation of abundant interfacial Ni^δ+ sites and favorable surface Ce³⁺–O–Al structures, which effectively promoted the accommodation and migration of active hydrogen species and activated adsorption of CO₂, thereby facilitating the generation of key formate and CO intermediates and subsequent conversions to produce methane. This study provides a new approach for the construction of high-performance Ni-based catalysts for low-temperature CO₂ methanation and gives deep insight into the critical roles of surficial/interfacial active structures in boosting CO₂ hydrogenation to produce methane.