Sm-doped NiMgAl hydrotalcite-derived catalyst for enhanced low-temperature CO2 methanation

Developing high-performance Ni-based catalysts for low-temperature CO 2 methanation remains challenging due to Ni particle aggregation caused by weak metal-support interactions at high loadings. To address this issue, Sm-modified Ni catalysts were prepared via direct reduction of Sm-doped NiMgAl layered double hydroxide precursors. The optimized 1.0Sm-NiMgAl-R catalyst exhibited markedly improved activity and stability compared to the unmodified sample, maintaining a 53 % CO 2 conversion and a CH 4 productivity of 142 mmol g cat −1  h −1 during a 115-h test at 240 °C. H 2 -TPR and XPS analyses revealed that Sm promoted electron transfer to Ni, which strengthened the metal–support interaction and stabilized the Ni nanoparticles. CO 2 -TPD and O 1s XPS confirmed that Sm incorporation promoted the formation of weak/medium basic sites and surface oxygen vacancies, facilitating CO 2 activation. In situ DRIFTS showed that Sm doping favored the formate pathway via enhanced ∗HCOO formation and suppressed carbonate species (∗HCO 3 ) under low-temperature conditions, leading to improved methanation performance. This work offers a novel strategy for designing efficient and sustainable catalysts for low-temperature CO 2 methanation.