High-Performance NiMn-LDO Catalysts for Efficient CO₂ Methanation.

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• Nickel-based catalysts for CO2 methanation suffer from sintering at high temperatures and low activity at low temperatures.
• Developing stable and active catalysts for CO2 methanation is crucial for carbon capture and utilization.

Purpose of the Study:

• To synthesize NiMn-LDO composite catalysts using hydrotalcite precursors.
• To investigate the impact of hydrogen reduction pretreatment and Ni/Mn ratios on catalytic performance for CO2 methanation.

Main Methods:

• Hydrotalcite precursor synthesis and calcination to form layered double hydroxide (LDO).
• NiMn-LDO composite catalyst preparation with varying Ni/Mn ratios.
• Catalytic testing for CO2 methanation at low temperatures.
• Characterization using techniques like BET, XRD, H2-TPR, and in situ DRIFTS.

Main Results:

• The NiMn(3:1)-LDO catalyst demonstrated exceptional performance, achieving over 90% CO2 conversion and CH4 selectivity at 230 °C.
• Hydrogen reduction pretreatment enhanced specific surface area, porosity, and active sites, improving structural properties.
• Optimized metal valence states and enhanced reduction capability were observed.
• In situ DRIFTS confirmed the CO2 methanation proceeds via the formate route.

Conclusions:

• NiMn-LDO composite catalysts offer a promising solution for low-temperature CO2 methanation.
• Hydrogen reduction pretreatment and controlled Ni/Mn ratios are key factors for enhancing catalyst performance.
• This research provides valuable insights for developing efficient CO2 methanation technologies.