CO2 capture and methanation using Ru/Na2O/Al2O3 dual-function materials: Effect of support synthesis method and Ru load

Ru/Na2O/Al2O3 dual-function materials were prepared by varying the support synthesis method and Ru load. Different sol-gel-type and precipitation/ hydrothermal preparation methods were employed in order to synthesize materials with variable nanostructure, surface chemistry and textural properties, thereby effectively tuning the material activity for the methanation of pre-adsorbed CO2. The materials were thoroughly characterized and evaluated during the integrated CO2 capture and methanation process. It was found that the Pechini sol-gel synthesis method led to the structure with the highest porosity, basic site population and high dispersion of methanation and adsorption active Ru0 and Al-O--Na+ sites. The corresponding material displayed the highest CH4 yield (0.47 mmol/g) and fastest CH4 production kinetics, while stable performance was achieved under successive adsorption-hydrogenation cycles and under the co-presence of O2 and H2O during CO2 adsorption. Lastly, the increase in Ru load (0.25 wt% - 4 wt% range) could incrementally improve the CH4 production kinetics during hydrogenation.