MgH₂-modified Ni catalysts with electron transfer behavior for improving CO₂ methanation

Area of Science:

• Materials Science
• Catalysis
• Chemical Engineering

Background:

• CO₂ methanation is vital for carbon utilization.
• Enhancing electron density at active sites is key for CO₂ activation.
• Modulating nickel (Ni) catalyst activity via metal hydrides is underexplored.

Purpose of the Study:

• To investigate the effect of magnesium hydride (MgH₂) on Ni catalyst performance for CO₂ methanation.
• To explore a simple method for increasing the electron density of Ni catalysts.

Main Methods:

• Preparation of MgH₂-xNi catalysts using mechanical ball-milling.
• Evaluation of catalytic activity in CO₂ methanation.
• Characterization using various techniques and density functional theory (DFT) calculations.

Main Results:

• MgH₂ addition significantly improved Ni catalyst activity, achieving 91.78% CO₂ conversion and 99.48% CH₄ selectivity at 350 °C for MgH₂-5Ni.
• Characterization confirmed increased electron density on Ni, higher surface-adsorbed oxygen, and more basic sites.
• DFT calculations validated enhanced CO₂ adsorption/activation and reduced energy barriers for key reaction intermediates.

Conclusions:

• MgH₂ effectively enhances Ni catalytic activity for CO₂ methanation by increasing electron density.
• The prepared MgH₂-xNi catalysts show superior performance.
• This study presents a facile and effective strategy for developing advanced catalysts for CO₂ methanation.