Ethanol steam reforming over Ni–Fe-based hydrotalcites: Effect of iron content and reaction temperature

Ethanol steam reforming has been evaluated over nickel–iron based hydrotalcite-like compounds with Ni/Fe molar ratios of 1 and 0.5. Calcined materials have been characterized by XRD, TEM, BET and TPR. The introduction of iron leads to the formation of a mixture of Ni(Fe)Ox and spinel phase upon calcination, which results in variations of structural and catalytic properties. With a Ni/Fe ratio of 1, a remarkable improvement in catalytic activity as well as selectivity to hydrogen is observed with respect to the catalyst with Ni/Fe ratio of 0.5. This is due to the enhanced nickel dispersion, the high surface area, and small Ni0 crystallite size over the Ni(Fe)Ox + NiFe2O4 mixture. However, a further increase in iron content leads to the formation of a low surface area spinel phase (NiFe2O4), which results in lower activity and faster deactivation in the reaction through Ni0 sintering. The effect of reaction temperature has been evaluated over the most active catalyst (Ni/Fe = 1).

► Ethanol steam reforming over nickel-iron mixed oxides.
► Excess of iron induce the formation of low surface area spinel with lower activity.
► Small Ni crystallite size and higher surface area are decisive for improved performance.