High-Performance NiMn-LDO Catalysts for Efficient CO₂ Methanation

In response to the issue of Ni-based catalysts, they exhibit easy sintering at high temperatures and low catalytic activity at low temperatures in the CO₂ methanation reaction. In this study, NiMn-LDO composite catalysts were synthesized using hydrotalcite as a precursor to investigate the effects of hydrogen reduction pretreatment conditions and the Ni/Mn ratios on the catalytic performance for CO₂ methanation. It was observed that the NiMn(3:1)-LDO catalyst exhibited exceptional performance, characterized by maintaining over 90% CO₂ conversion and CH₄ selectivity after prolonged testing at a low temperature of 230 °C. Further characterization analysis indicated that the hydrogen reduction pretreatment facilitated an increase in the catalyst's specific surface area and porosity, optimized its structural properties, and provided more active sites. Additionally, the shift of metal elements from higher to lower valence states enhanced the catalyst's reduction capability. In situ DRIFTS analysis reveals that the CO₂ methanation process proceeds via the formate route. This study provides new ideas and methods for developing CO₂ methanation technology.