Enhanced low-temperature CO₂ methanation over La-promoted NiMgAl LDH derived catalyst: Fine-tuning La loading for an optimal performance

LDH-derived Ni-based catalysts are gathering momentum due to their excellent thermal stability but their low-temperature CO₂ methanation is limited. In this study, various concentrations of La were introduced into the LDH-derived Ni-based catalysts for CO₂ methanation, and the underlying mechanisms were investigated. The optimal Ni/La_0.2-MgAlO_x catalyst presented a CO₂ conversion level of 69.0 % at 225 °C, which is over 7 times higher than that of conventional Ni/MgAlO_x. The addition of small amounts of La could significantly enhance H spillover to promote the reduction of Ni species, but the oxygen vacancy concentration became the dominant factor causing changes in low-temperature activity as the La contents continue to increase. CO₂ was found to be adsorbed at the oxygen vacancies in the form of bidentate carbonates, which are more reactive under an enhanced electron-rich environment. The research offers guidance to design effective and sustainable catalysts for low-temperature CO₂ methanation.