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

摘要

CeO2 and La2O3 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 gamma-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 equivalent to gamma-NiO/La2O3. In contrast, for 5-Ni/La and 20-Ni/Ce catalysts, gamma-NiO active sites incorporated into support is available.