Dry reforming of methane over Pt-Ni/CeO2 catalysts: Effect of the metal composition on the stability

A series of Pt-Ni/CeO2 catalysts with different Pt:Ni atomic ratios were synthetized through incipient wetness impregnation over CeO2 prepared by precipitation. Catalysts were characterized by XRD, EDS-SEM, N-2-Adsorption, TEM-STEM, H-2-TPR, CO-DRIFTS and O-2-TPO. Samples were studied in the Dry Reforming of Methane (DRM) reaction. The catalytic activity of nickel-ceria catalysts was improved by addition of platinum at any composition, and the behavior of bimetallic Pt-Ni/CeO2 catalysts resembled to that exhibited by the platinum-ceria sample. Stability results showed that bimetallic catalysts presented a steady behavior, with no deactivation after 24 h on-stream and enhanced anti-coke properties by the presence of platinum, while the H-2/CO ratio at all metal compositions was superior compared to that of monometallic samples. Nickel not only contributes to the methane activation, but also to the hydrogen production. The enhancement of the catalytic properties of Pt-Ni/CeO2 catalysts was explained through a synergic effect between the two metals which impacted in the metal dispersion, the reduction properties and the stabilization of the surface structure of the active ensembles.