Dry reforming of methane on bimetallic Co-Ni/CeO2 catalyst

In the present work, monometallic Co/CeO2 (Co 7.5 wt.%) and Ni/CeO2 (Ni 7.5 wt.%) catalysts, were compared with the bimetallic Co-Ni/CeO2 (Co 3.75 wt.%, Ni 3.75 wt.%) catalyst. CeO2 has been selected for its redox properties that may mitigate the carbon deposition. The synthesis by surfactant assisted co-precipitation method allowed us to obtain powders with high surface area and homogeneous dispersion of cobalt and nickel nanometric particles. Samples were characterized by XRD, BET, TPR, TG-DTA and tested for DRM with CH4:CO2:Ar 20:20:60 vol.% (GHSW = 30000 mL g-1 h-1). After activation in H2 at 800°C, Co-Ni/CeO2 clearly showed the presence of a cobalt and nickel alloy phase. The bimetallic Co-Ni/CeO2 catalyst was more active and more selective for the DRM reaction than monometallic Co/CeO2 and Ni/CeO2 samples. In particular the CH4 conversion on Co-Ni/CeO2 was 50% at 600°C, and 97% at 800°C, with a H2/CO ratio in the range 0.9-1.0. After 16 hours streaming, Ni/CeO2 showed 25 wt.% of carbonaceous deposit and a catalytic activity decrease of 8%, while both cobalt containing catalysts showed 6 wt.% of carbon on the surface and a decrease of activity less than 2%. Theses features suggest that cobalt-nickel alloy combines the high activity of nickel with the carbon suppression property of cobalt.