The effects of bimetallic Co-Ru nanoparticles on Co/RuO2/Al2O3 catalysts for the water gas shift and methanation

The effects of Co on RuO2/Al2O3's activities for water gas shift (WGS) and methanation were studied. Catalysts were characterized with BET, XRD, SEM/EDS, H2-TPR and CO-TPR. The effects of various parameters, such as calcination temperature, Ru-Co loading, Ru/Co ratio, inlet CO concentration and H2O/CO ratio on the activities of catalysts were investigated. There existed CoI (strongly interact with RuO2) and CoII (weakly interact with RuO2). For Co/RuO2/Al2O3 (Ru/Co = 1, AT = 350), only CoI existed as bimetallic Co-Ru nanoparticles. This unique structure led this catalyst to achieve the highest CO conversion of 98.6% exceeding WGS's theoretical thermodynamic equilibrium limit due to the co-occurrence of methanation. Co/RuO2/Al2O3 was more favorable to catalyze CO methanation than CO2 methanation. The apparent activation energies of forward and reverse WGS catalyzed by Co/RuO2/Al2O3 were 37.8 and 74.6 kJ mol−1, respectively. The difference was corresponding well to the enthalpy change (−41.1 kJ mol−1) of WGS.