Structural characterisation of Ni/alumina reforming catalysts activated at high temperatures

• A relationship between Ni0 particle size and NiO/NiAl2O4 ratios was extracted.
• Small Ni particle size (6 nm) was obtained at low NiO/NiAl2O4 ratio.
• NiAl2O4/Al2O3 has a much better textural and nano-structural stability than NiAl2O4.
• The surface acidity of NiAl2O4/Al2O3 may be modulated by varying the Ni content.
• 70%NiAl2O4/Al2O3 exhibited a high activity in the steam reforming of methane.

This paper is devoted to the characterisation of Ni/alumina reforming catalysts. A special attention was paid to the control of the catalytic properties by the synthesis route of bulk and supported catalysts. In this sense it was shown that the massive formation of NiAl2O4 phase, associated with low NiO/NiAl2O4 molar ratios on the catalyst surface, due to a calcination step at high temperatures was notably beneficial for obtaining highly dispersed nickel catalysts (with a Ni crystallite size of 6 nm) after severe reduction at 850 °C. This activation procedure did not affect textural and acidic properties to a large extent. Thus, among the investigated nickel catalysts the 70%NiAl2O4/Al2O3 sample exhibited the best performance in the steam reforming of methane.

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