Cyclic performance in CO2 capture-methanation of bifunctional Ru with different base metals: Effect of the reactivity of COx ad-species

Bifunctional materials based on Ru nanoparticles and an alkaline metal (K, Na or Ba) have been scrutinized for several cycles of CO2 capture and subsequent methanation at different temperatures from 250 degrees C to 450 degrees C. The optimum performance in terms of stable cyclic operation, amount of captured CO2 and relevant methane pro-ductivity was attained at different temperature window for each material. For the materials here prepared, the limiting lower operation temperature of stable cyclic performance was determined by the methanation kinetics, which depended on reactivity of COx ad-species captured with each alkaline metal. The highest activity was found with Ba-containing materials, which exhibited a stable and relevant cyclic CH4 productivity at 250 degrees C, being one of the lowest operation temperatures reported for a dual functional material to date. This material exhibited stable cyclic performance also in the presence of O2 and H2O, although the CH4 productivity decreases slightly and reversibly compared to that using CO2 containing gas free of O2 and H2O.