The role of Ru clusters in Fe carbide suppression for the reverse water gas shift reaction over electropromoted Ru/FeOx catalysts

Abstract

The formation of an iron carbide phase has been shown to inhibit the efficiency of Fe-based catalysts in the initial step of adsorbing carbon dioxide (CO2). In this study, we evaluate the effect of adding Ru clusters (20% at.) to FeOx nanowires deposited on yttria-stabilized zirconia (YSZ) for the reverse water gas shift (RWGS) reaction carried out at 300–400 °C under atmospheric conditions. STEM shows that Ru-FeOx formed a bi-phase structure with Ru clusters (1.5–2 nm) supported on FeOx nanowires (5 nm) that remain as mixed oxides after the reaction. Open-circuit catalytic measurements demonstrated that addition of Ru increased the catalytic activity and stabilized high selectivity (>99%) towards CO. The synergetic effect of Ru and FeOx was further emphasized through electrochemical polarization, which led to a reversible catalytic activity increase of up to 2.4 times. The addition of Ru inhibits the formation of inactive Fe carbide by acting as the reducing component and stabilizing the FeOx active state. This results in an improved and lasting catalytic performance and makes Ru/FeOx catalysts attractive for industrial applications.

Keywords

• Electrochemical promotion of catalysis
• NEMCA
• Reverse water–gas shift
• Iron-oxide
• Ruthenium
• Iron-carbide