Abstract
<title>Abstract</title> <p>Four CeO₂ containing bimetallic formulations CuNi/CeO₂, AuRu/CeO₂, FeCu/CeO₂, and AgNi/CeO₂ were evaluated as a preliminary activity/selectivity screening set for the reverse water-gas shift (RWGS) and methanation pathways. The formulations were tested using the same fixed-bed reaction protocol from 40 to 350°C, but they do not constitute a strict single-variable catalyst series: the metal pairs and nominal precursor ratios differ, and AuRu/CeO₂ was synthesized by a different route. SEM–EDS verified the presence and microscale distribution of the target elements, N₂ physisorption described the mesoporous CeO₂ support, and XRD showed that cubic fluorite CeO₂ remained the dominant crystalline phase. CuNi/CeO₂ gave the highest CO₂ conversion (50.94% at 350°C), FeCu/CeO₂ gave the highest CO formation rate (624 µmol g⁻¹ h⁻¹), AuRu/CeO₂ gave the highest CH₄ formation rate (545 µmol g⁻¹ h⁻¹), and AgNi/CeO₂ retained the highest CH₄ selectivity at 350°C (76.6%). These results identify formulation-level performance trends only; they do not establish intrinsic effects of metal identity, metal ratio, preparation route, active-site structure, or reaction mechanism.</p>