Catalytic Oxidation of Carbon Monoxide over CeO₂ and La₂O₃ Oxides Supported Nickel Catalysts: The Effect of the Support and NiO Loading

Abstract

CeO2 and La2O3 oxides supported NiO loading (5 and 20 wt%) were synthesized, characterized by ICP‐AES, XRD, IR‐ATR, SEM, B.E.T, H2‐TPR and applied to CO oxidation with and without pretreatment under H2 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 H2 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/La2O3. In contrast, for 5‐Ni/La and 20‐Ni/Ce catalysts, γ‐NiO active sites incorporated into support is available.