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

Abstract

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/La0.2-MgAlOx catalyst presented a CO2 conversion level of 69.0 % at 225 °C, which is over 7 times higher than that of conventional Ni/MgAlOx. 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.