Synergistic Ru-Fe-Ca interfaces enable low-temperature CO₂ methanation over γ-Al₂O₃-supported nanocomposites

Ru/Fe/Ca (5 : 25 : 70)/γ-Al₂O₃ nanocomposites for CO₂ methanation were prepared by wet impregnation. Catalytic performance evaluation was carried out under atmospheric pressure with an H₂ : CO₂ ratio of 4 : 1 over a temperature range of 50-300 °C. The findings showed that the Ru/Fe/Ca (5 : 25 : 70)/γ-Al₂O₃ catalyst calcined at 1000 °C achieved 85.59% CO₂ conversion and 79.58% methane yield at 300 °C. XRD and BET analyses revealed mesoporous features, with a surface area of 34.58 m² g^-1. FESEM analysis further showed that the catalyst had a circular morphology, with particle sizes ranging from 65 to 87 nm. EDX confirmed the distribution of the constituent elements, while XRD identified RuO₂ as a prominent Ru-containing phase associated with enhanced catalytic performance. The mechanistic study showed that carboxylate species are important intermediates in FTIR studies, which are hydrogenated and ultimately lead to methane formation. The results indicate that catalytic performance is associated with synergistic interactions among Ru-, Fe-, and Ca-containing species and their interaction with the γ-Al₂O₃ support, enabling efficient CO₂ conversion and CH₄ formation at 300 °C. Further studies of long-term stability, carbon deposition, and catalyst regeneration are needed to assess the catalyst's durability under continuous methanation conditions.