The Role of Gadolinia Doped Ceria Support on the Promotion of CO2 Methanation over Ni and Ni-Fe Catalysts

In the present work, CO2 methanation was investigated over Ni, Fe, Ni3Fe1, Ni1Fe1 and Ni1Fe3 catalysts supported on Gadolinia Doped Ceria (GDC) in the temperature range 200-400 °C. Both CO2 and H2 conversion decreased in the order Ni/GDC > Ni3Fe1/GDC > Ni1Fe1/GDC > Ni1Fe3/GDC. No catalytic activity was displayed by Fe/GDC. Maximum CO2 conversion (>90%) was observed at 400° C, with almost 100% selectivity to CH4. The catalysts were characterized by X Ray Diffraction (XRD), N2 adsorption/desorption, H2 - Temperature Programmed Reduction (H2-TPR), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and CO2 Temperature Programmed Desorption (CO2-TPD). The superior activity of monometallic Ni/GDC with respect to bimetallic Ni-Fe/GDC catalysts was ascribed to the presence of surface oxygen vacancies induced by the GDC support, as well as to the ability of the Ni-GDC to interact with CO2, as suggested by XPS data.