In-situ methanation of adsorbed CO over Ni/CeO2 catalyst using H2 release from vanadium powder as H2-storage material

Abstract

This study examines the feasibility of using a physical mixture of Ni/CeO₂ catalyst and vanadium (V) powder (as an H₂-storage material) for methanation of dilute CO. The system principle involves CO adsorption onto the Ni/CeO₂ catalyst and H₂ storage in V powder at a low temperature (∼50 °C). Subsequently, temperature increase of the physical mixture under an inert gas flow triggers H₂ release from the V powder, enabling in-situ methanation of the adsorbed CO on the Ni/CeO₂ catalyst. An optimized Ni/CeO₂:V weight ratio of 1:1 results in a high conversion (76 %) of the initially adsorbed CO, yielding 0.29 μmol of CH₄. The system demonstrates feasibility of processing a dilute feed stream, producing CH₄ even when only 1 % CO is used during adsorption. However, cyclic testing reveals significant durability issues. The performance degradation is attributed to two factors that diminish the H₂-release capacity of V powder: (i) surface oxidation by product water and (ii) detrimental V-O-Ce interfacial interactions during thermal cycling. Despite these limitations, this study demonstrates the potential of coupling catalytic reactions with H₂-storage materials for the effective utilization of dilute gas streams.