Controlling the impregnation of nickel on nanoporous aluminum oxide nanoliths as catalysts for partial oxidation of methane

• NiO incorporation into AAO nanoliths pores has been successfully achieved.
• The three impregnation methods tested can incorporate NiO into the nanoliths pores.
• A low Ni2+ concentration (0.14 M) during the impregnation is a key factor.
• The addition of NiO into the pores entails the incorporation of the nanolith faces.

Three different conventional impregnation methods were studied in order to elucidate the effect of impregnation variables on the homogeneity in the incorporation of Ni species into the nanoporous structure of the aluminum oxide nanoliths. From results obtained in this study, two factors seem to control the Ni incorporation onto the aluminium oxide nanostructure: (i) the methodology used in the impregnation: incipient wetness impregnation, wet impregnation, or forced wet impregnation, and (ii) the Ni precursor concentration used during the impregnation process. Both the nickel loading and the nickel distribution entities inside the porous structure of aluminium oxide nanoliths depend on the method and concentration of the Ni impregnating solution used in the impregnation. The distribution of the NiO loaded on nanoliths was not uniform as SEM analyses demonstrated. Segregation of NiO entities on surface of AOO nanolith was observed in all samples. For impregnation with Ni solution of low concentration, only incipient wetness impregnation and forced wet impregnation allows the deposit of nickel entities on the porous structure of the AAO nanoliths. By increasing the Ni concentration in the impregnating solution, a larger degree of pore coverage was obtained for all impregnation methods used.

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