Effect of Ni/Fe ratio in Ni–Fe catalysts prepared under external magnetic field on CO₂ methanation

Background: The power-to-gas (PtG) method has significant potential as a strategy for storing excess renewable energy in the form of synthetic natural gas. PtG involves the hydrogenation of CO₂ to CH₄ from H₂ obtained from renewable energy. Methods: In this study, Ni–Fe catalysts with different Ni/Fe ratios were prepared for high-efficiency CO₂ methanation using chemical reduction with an external magnetic field. The Ni–Fe catalysts were characterized by XRD, inductively coupled plasma, and SEM-EDS measurements, and their performance and chemical properties were measured by H₂ temperature programmed reduction experiments. Significant findings: The catalyst with the best performance for CO₂ methanation had a ratio of Ni to Fe of 8/2 (Ni₈Fe₂). The Ni₈Fe₂ catalyst could convert over 80% of CO₂ to methane at 150 °C. In addition, the CH₄ selectivity of CO₂ methanation was 95% when the reaction conditions were controlled at H₂/CO₂ = 4 and GHSV ∼1000 h⁻¹. The low cost and simple preparation of these Ni–Fe catalysts have high potential for future commercialization.