Catalytic Oxidation of Carbon Monoxide over CeO 2 and La 2 O 3 Oxides Supported Nickel Catalysts: The Effect of the Support and NiO Loading

CeO 2 and La 2 O 3 oxides supported NiO loading (5 and 20 wt%) were synthesized, characterized by ICP‐AES, XRD, IR‐ATR, SEM, B.E.T, H 2 ‐TPR and applied to CO oxidation with and without pretreatment under H 2 atmosphere. It was shown that the support has a significant effect on the bulk, surface and reactivity properties. The reduction of nickel to metallic species occurred at higher temperatures in ceria case. 20‐Ni/La sample showed the best catalytic activity without reduction but this behavior mitigates when the sample pretreated under H 2 indicating that the presence of different kinds sites responsible of CO oxidation. An opposite reactivity property was obtained in 5‐Ni/La and 20‐Ni/La cases and the interfacial γ‐type NiO interactions decreases with NiO loading which was coincident with CO oxidation activity. The active species in 20‐Ni/La sample is of type metal/support interface≡γ‐NiO/La 2 O 3 . In contrast, for 5‐Ni/La and 20‐Ni/Ce catalysts, γ‐NiO active sites incorporated into support is available.